Patent Publication Number: US-11649967-B2

Title: Knob assembly for cook top

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/845,643, filed on Apr. 10, 2020, which is a continuation of U.S. application Ser. No. 15/900,251, filed on Feb. 20, 2018, now U.S. Pat. No. 10,663,172, which claims priority to and the benefit of Korean Patent Application No. 10-2017-0021878, filed on Feb. 17, 2017, Korean Patent Application No. 10-2017-0094807, filed on Jul. 26, 2017, and Korean Patent Application No. 10-2017-0167072, filed on Dec. 6, 2017, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The present disclosure relates to a knob assembly for adjusting a timer and a firepower level of a cooking appliance, and a cooking appliance including the same. 
     BACKGROUND 
     A cooking appliance can be classified variously, for example, according to the kind of fuel, a heat source, a form, etc., and may be one of home appliances for cooking food. 
     For example, the cooking appliance may be classified into an open type and a closed type depending on the form of a space where food is placed. 
     A closed type cooking appliance is a cooking appliance that closes the space where food is placed and cooks food by heating a closed space. For example, an oven, a microwave oven, etc. may belong to the closed type cooking appliance. 
     An open type cooking appliance is a cooking appliance that cooks food by heating a food item or a food container in an open space. For example, a cooktop, a hob, etc. may belong to the open the cooking appliance. 
     In some examples, the closed type cooking appliance and the open type cooking appliance may be installed in a single product, and a composite cooking appliance is proposed in which a plurality of heat sources are combined to cook various types of food or a plurality of items of food. 
     For example, in the composite cooking appliance, the open type cooking appliance may be arranged on the upper side of the closed type cooking appliance. The open cooking appliance may include a plurality of heaters or burners to enable cooking of a plurality items of food at the same time. 
     One example of the open type cooking appliance is a gas range that uses gas as a fuel. A gas range is a device that cooks food using a flame generated by burning gas. 
     There are various ways for a user to control an intensity of the flame of the cooking appliance. For example, a method of controlling firepower by adjusting the amount of rotation of a knob by using the knob rotating around a predetermined adjustment shaft are mostly used. 
     In some examples, the cooking appliance using gas may include a structure in which the amount of opening and closing of the valve of supplying gas is controlled according to the amount of rotation of the knob. In some cases, for safety, a gas valve may rotate with the knob only when the knob is pressed and rotated. 
     In some examples, the closed type cooking appliance may be used for a long time cooking, and may include a timer for setting a cooking time. In other examples, the open type cooking appliance may include a timer having a cooking time alarm function in order to improve a user convenience. 
     SUMMARY 
     The present disclosure may provide a fire power controlling knob assembly capable of setting a timer by using a knob ring arranged around a knob for controlling the fire power and displaying information, and a cooking appliance including the same. 
     The present disclosure may mitigate a misalignment of the knob due to an accumulation of an assembly tolerance. A misalignment may cause a degrade of an appearance quality due to a position error of the knob, or operation failure, for example, for fitting the knob. 
     The present disclosure may provide a support structure in which the knob connected to a valve assembly can be stably supported, thereby improving a reliability of a knob operation. 
     The present disclosure may provide a structure that can stably couple a display device to a knob ring in which the display device can be properly insulated. 
     The present disclosure may provide a structure that restricts rotation of the knob in a state where the knob is not pushed, in a knock operation structure in a push and turn manner. 
     The present disclosure may enable a fine adjustment of a flow rate of the valve assembly according to an installation environment, and to facilitate the fine adjustment of the flow rate without separating the cooking appliance. 
     The present disclosure may provide a knob assembly in which a joint is arranged between a knob and a valve assembly so that assembly tolerance, etc. generated in the valve assembly may not be transferred to the knob. 
     The present disclosure may provide a knob assembly for allowing the joint to absorb a position error of a valve shaft so that the knob can be assembled at a predetermined position with regard to a front panel at a predetermined amount of protrusion. 
     The present disclosure may provide a knob assembly that is rotatable about a knob ring arranged in the periphery of the knob, wherein the knob ring can stably rotate and always return to a predetermined position by an elastic force. 
     The present disclosure may provide a knob assembly that allows the knob ring to be fixed constant in its initial position. 
     The present disclosure may provide a knob assembly having a sensor capable of sensing the amount of rotation of a valve shaft and capable of display the size of the fire power on the display device provided on the knob ring by using the sensed amount of rotation of the valve shaft. 
     The present disclosure may provide a knob assembly that uses a Hall sensor and a magnet as a sensor for sensing the amount of rotation of the valve shaft, and can maintain a constant spacing between the Hall sensor and the magnet even when an operation of the knob is repeated. 
     The knob assembly according to the present disclosure can be fixed in a state in which the knob handle is aligned in the front panel, thereby improving the appearance quality of the cooking appliance. 
     In addition, the knob assembly according to the present disclosure absorbs the position error of the valve shaft of the valve assembly in the joint, and a knob shaft coupled to the knob handle can be stably supported on the knob ring, which may mitigate a fitting problem generated during operation of the knob handle. 
     The knob assembly according to the present disclosure may include a knob ring which can be independently operated at a circumference of the knob handle so that the timer time of the cooker such as the corresponding burner or the oven can be set through the operation of the knob ring. 
     In some implementations, the display device is provided in the knob ring, and the fire power or the timer time, etc. of the corresponding cooker can be displayed on the display device, thereby resulting in an effect of improving convenience for a user. For example, the display device may have the structure which is coupled to a knob ring body in a state surrounded by a side to the display housing, which is an insulating material, resulting in an effect of securing insulation performance of the display device even when the knob ring body is formed of a metal material. 
     In some implementations, the knob assembly according to the present disclosure can be stably operated in a state which the position of the knob ring is fixed with regard to the front panel, and by providing a structure in which the knob shaft of the knob is supported to the knob ring, resulting in an effect which can be aligned at a predetermined position with regard to the front panel of the knob handle and the knob ring. 
     According to the present disclosure, it may be possible to stably provide a measurement result of the knob rotation amount with high accuracy without a noise, and to provide an effect of stably perform an operation control for outputting a rotation state of the knob handle, or the control with regard to the operation performed through the rotation of the knob handle. 
     In some implementations, the present disclosure not only contributes to a significant reduction in the risk of generating fire due to gas leakage but also secures information on the failure of components for securing the rotation of the knob handle quickly and accurately. It may be possible to provide a highly reliable sensing result since an error due to a noise or an error of an electronic component may be prevented. In some implementations, by providing an independent operation switch having a function and a shape different from those of an existing knob ring by using a knob ring installed for finishing the knob handle, so that the user can easily select an operation switch suitable for the use, thereby providing improved use convenience, and, by reducing the number of the operation switch arranged on the front surface of the cooking appliance, thereby improving a sense of beauty of the front surface of the device. 
     In some implementations, the present disclosure may provide a function in which a physical power transmission operation through a knob handle operation and a sensing operation for sensing an operation of the knob handle are simultaneously performed, while suppressing an increase of parts, an assembly process, and a manufacturing cost required for implementing this function. The manufacturing operation may be performed more easily. The present disclosure may effectively improve sensing performance of the operation of the operation switch such as the knob handle and the knob ring. 
     In some implementations, when two shafts are connected to both ends of the joint, respectively, a connection angle between the first shaft supporting portion and the second shaft connecting portion may be set to a state suitable for connecting the two shafts, and this state can be maintained or changed in accordance with the situation by the elastic force of the elastic member. 
     Therefore, the present disclosure may provide an effect of capable of effectively absorbing the position error between two shafts without a separate operation for controlling the connecting angle of the first shaft supporting portion and the second shaft supporting portion, and separate operation for fixing an adjusted connecting angle of the first shaft supporting portion and the second shaft supporting portion, and accordingly, effectively connecting two parts which are difficult to be connected to the same axis. 
     In some implementations, an installation process is possible without the additional operation for adjusting the connection angle, by making the joint be assembled with only a small number of parts, the part management and an assembly operation can be easily made and the cost and time required for the manufacturing of the joint can be reduced. 
     In some implementations, the present disclosure can prevent a return position deviation of the knob ring provided by the independent operation switch from being generated, thereby effectively preventing an appearance defect of the cooking appliance due to the return defect of the knob ring from being generated. 
     In some implementations, since a rotation operation of knob ring is possible by applying force beyond a predetermined degree, an operating mistake of the knob ring may be prevented, and the operation feeling for easily recognizing the start of rotation of the knob ring can be provided to the user. 
     In some implementations, the present disclosure also provides a valve pushing force compensating structure which absorbs an influence due to performance deviation of the valve pressing force so that the valve can be opened only by a pushing force of beyond predetermined level, and thus, it may be possible to reduce a risk generating safety accidents such as fire due to a potential opening of the valve that is not made by an intended operation of the user. 
     According to one aspect of the subject matter described in this application, a knob assembly includes a front panel that defines an appearance of an appliance, a knob located at a front side of the front panel and configured to rotate based on operation by a user, a knob shaft that is coupled to the knob and that extends through the front panel, a supporting pipe that receives the knob shaft and that supports the knob shaft, the supporting pipe being configured to maintain a position relative to the front panel, a valve located in the appliance and configured to control supply of gas to the appliance, a valve shaft connected to the valve and configured to control the valve to adjust a flow rate of gas based on rotation of the valve shaft, and a joint that couples the knob shaft to the valve shaft and that is configured to transfer at least one of a rotational motion or a linear motion of the knob shaft to the valve shaft. 
     Implementations according to this aspect may include one or more of the following features. For example, the supporting pipe may include an outer supporting pipe that extends forward of the front panel along a line, and an inner supporting pipe that extends rearward of the front panel along the line. The knob shaft is configured to pass through the outer supporting pipe and the inner supporting pipe. The knob assembly may further include a knob ring located between the front panel and the knob and configured to receive the knob shaft in which the supporting pipe extends from the knob ring. The knob ring may be configured to rotate independently of rotation of the knob based on operation by a user, and the knob ring may include a handle that protrudes forward of the knob and that is configured to receive input from the user. 
     In some implementations, the joint may include a first shaft coupling portion configured to couple to the valve shaft, a second shaft coupling portion configured to couple to the knob shaft, a joint spring that is located between the first shaft coupling portion and the second shaft coupling portion, and that allows the knob shaft to couple to the valve shaft regardless of deviation of at least one of the knob shaft or the valve shaft from a coaxial direction, and a joint housing that accommodates the first shaft coupling portion, the second shaft coupling portion, and the joint spring, and that is configured to transfer a rotational motion of the first shaft coupling portion to the second shaft coupling portion. 
     In some examples, the valve may include a valve body that defines a gas flow path, a main adjustment part that is located inside of the valve body, and that is configured to, based on the main adjustment part being rotated by the valve shaft, control a flow rate of gas in the gas flow path, an auxiliary adjustment part that is located at a side of the main adjustment part in of the valve body, and that is configured to, based on the auxiliary adjustment part being rotated by a separate tool, control the flow rate of gas in the gas flow path, and a valve cap that is coupled to a front side of the valve body and that covers the front side of the valve body. The front panel may define a service hole that is located at a position corresponding to a projection of the auxiliary adjustment part to the front panel, and that allows access to the auxiliary adjustment part in a state in which the knob is separated from the front panel. 
     In some implementations, the knob assembly may further include a knob sensor configured to sense rotation of the valve shaft, and the valve cap includes a sensor fixing portion coupled to the knob sensor. The knob sensor may include a sensor plate configured to couple to the sensor fixing portion, a knob sensor housing configured to maintain a posture relative to the sensor plate, a sensor board configured to couple to the knob sensor housing, a plurality of Hall sensors that are radially arranged on the sensor board and that defines a sensing range, a rotating plate configured to couple to the valve shaft and rotate based on rotation of the valve shaft, and a knob sensor magnet located at the rotating plate and configured to pass the sensing range of the plurality of Hall sensors based on rotation of the valve shaft. The valve shaft may be configured to penetrate the sensor plate, the knob sensor housing, and the sensor board. 
     In some implementations, the knob assembly may further include a sensor spring that is located between the sensor plate and the knob sensor housing, and that is configured to provide elastic force to the knob sensor housing toward the rotating plate. In some examples, the knob assembly may further include a fixed pipe configured to couple to a rear side of the front panel and to support the knob shaft between the supporting pipe and the joint. The knob assembly may further include a support frame that is configured to receive the supporting pipe, that is configured to couple to the rear side of the front panel, and that defines a support frame through hole; and a fixed frame that is configured to couple to the support frame and that extends across the support frame through hole in which the fixed pipe is configured to couple to the fixed frame. In some examples, the fixed pipe may include a second tube part configured to rotatably couple to a front end of the joint. 
     In some implementations, the knob assembly may further include a locking bracket including a locking piece that is configured to couple to the front side of the front panel, that protrudes to an inside of the knob, and that defines a passage groove at a rear side of the locking piece. The knob may include a guide surface that has a ring shape and that is configured to interfere with the locking piece in which the guide surface defines a cutting section configured to receive the locking piece in an initial position. The guide surface is further configured to (i) based on the knob being in the initial position, interfere with the locking piece to restrict rotation of the knob, and (ii) based on the knob being pushed from the initial position, define a plane coplanar with the passage groove to allow rotation of the knob. 
     In some examples, the knob may include a knob body that defines an appearance of the knob, and a knob back plate that is coupled to an inside of the knob body, and the guide surface is located at the knob back plate. 
     According to another aspect, an appliance including a burner may include a valve configured to control a flow rate of gas that flows to the burner, and a knob assembly configured to operate the valve. The knob assembly may include a front panel that defines a surface of the appliance, a knob located at a front side of the front panel and configured to rotate based on operation by a user, a knob shaft that is coupled to the knob and that extends from the knob through the front panel, a supporting pipe that receives the knob shaft and that supports the knob shaft, the supporting pipe being configured to maintain a position relative to the front panel, a valve shaft connected to the valve and configured to control flow of gas in the valve, and a joint that is configured to couple the knob shaft to the valve shaft and to transfer at least one of a rotational motion or a linear motion of the knob shaft to the valve shaft. 
     Implementations according to this aspect may include one or more of the following features. For example, the joint may include a first shaft coupling portion configured to couple to the valve shaft, and a second shaft coupling portion configured to couple to the knob shaft, and the joint is configured to, regardless of deviation of at least one of the knob shaft or the valve shaft from a coaxial direction, transfer at least one of a rotational motion or a linear motion of the second shaft coupling portion to the first shaft coupling portion. The knob assembly may further include a knob ring located between the front panel and the knob and configured to receive the knob shaft, and the supporting pipe may include an outer supporting pipe that extends forward from the knob ring, and an inner supporting pipe that extends rearward from the knob ring. 
     In some implementations, the knob ring may be configured to rotate independently of rotation of the knob based on operation by a user, and the knob ring may include a handle that protrudes forward of the knob and that is configured to receive input from the user. The joint further may include a joint spring that is located between the first shaft coupling portion and the second shaft coupling portion, and that allows the knob shaft to couple to the valve shaft regardless of deviation of at least one of the knob shaft or the valve shaft from the coaxial direction, and a joint housing that accommodates the first shaft coupling portion, the second shaft coupling portion, and the joint spring, and that is configured to transfer the rotational motion of the first shaft coupling portion to the second shaft coupling portion. 
     In some examples, the valve may include a valve body that defines a gas flow path, a main adjustment part that is located inside of the valve body and that is configured to, based on the valve shaft rotating the main adjustment part, control a flow rate of gas in the gas flow path, an auxiliary adjustment part that is located inside of the valve body at a side of the main adjustment part, and that is configured to, based on the auxiliary adjustment part being rotated by a separate tool, control the flow rate of gas in the gas flow path, and a valve cap that is coupled to a front side of the valve body and that covers the front side of the valve body. The front panel may define a service hole that is located at a position corresponding to a projection of the auxiliary adjustment part to the front panel, and that allows access to the auxiliary adjustment part in a state in which the knob is separated from the front panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view showing an example of a composite cooking appliance having a timer function. 
         FIG.  2    is a view showing an example of a position error of an example knob. 
         FIG.  3    is a perspective view illustrating an example fire power controlling knob assembly disposed in an example case. 
         FIG.  4    is a perspective view showing the knob assembly without a front panel in  FIG.  3     
         FIG.  5    is a perspective view showing the fire power controlling knob assembly separated into three portions. 
         FIG.  6    is a perspective view showing the knob assembly of  FIG.  4    viewed from a rear surface. 
         FIG.  7    is a side view of the knob assembly of  FIG.  4   . 
         FIG.  8    is a perspective view showing an example knob arranged at an outermost portion of an example case assembly. 
         FIG.  9    is a perspective view showing an example rear surface of the knob shown in  FIG.  8   . 
         FIG.  10    is a perspective view showing the knob of  FIG.  8   . 
         FIG.  11    is an exploded view showing the case assembly. 
         FIG.  12    is an exploded view showing an example inside of the case assembly. 
         FIG.  13    is a view showing an example arrangement inside of the front panel of the case assembly. 
         FIG.  14    is an exploded view showing example components arranged outside of the front panel of the case assembly. 
         FIG.  15    is a view showing an example state arranged outside of the front panel of the case cooking assembly. 
         FIG.  16    is a perspective view showing an example appearance of the knob ring in an assembled state. 
         FIGS.  17  and  18    are the exploded perspective views showing example assembly structures of the knob ring. 
         FIG.  19    is a perspective view of an example display device of an example knob assembly. 
         FIG.  20    is a perspective view showing a rear surface of an example display device. 
         FIG.  21    is a perspective view showing an example display housing. 
         FIG.  22    is a perspective view showing a rear surface of the display housing. 
         FIG.  23    is a perspective view showing a rear surface of an example knob ring of an example knob assembly. 
         FIGS.  24  and  25    are the views showing example coupling structures, an example display device, and an example knob assembly. 
         FIG.  26    is a perspective view showing an example knob ring back plate. 
         FIG.  27    is a perspective view showing a rear surface of the knob ring back plate. 
         FIG.  28    is a longitudinal sectional view showing an example knob ring. 
         FIG.  29    is a view showing an assembly of an example display cover. 
         FIG.  30    is a perspective view illustrating an example display cover. 
         FIG.  31    is a half sectional view showing an example display cover. 
         FIG.  32    is a sectional view showing an example state before the display cover of the knob assembly is coupled. 
         FIG.  33    is a cross-sectional view showing an example state in which an example display cover is coupled to the knob assembly. 
         FIG.  34    is a cross-sectional view showing an example joint separated from the knob assembly. 
         FIG.  35    is a perspective view showing an example joint of the knob assembly. 
         FIG.  36    is an exploded perspective view illustrating an example joint. 
         FIG.  37    is a longitudinal sectional view showing an example joint. 
         FIG.  38    is a transverse cross-sectional view showing an example joint. 
         FIG.  39    is a cross-sectional view showing an example joint portion. 
         FIGS.  40  and  41    are the views illustrating rotating operation of the joint. 
         FIG.  42    is a perspective view of an example valve assembly. 
         FIG.  43    is an exploded perspective view showing the valve assembly. 
         FIG.  44    is a perspective view showing an example valve. 
         FIG.  45    is an exploded perspective view showing an example valve. 
         FIG.  46    is a longitudinal sectional view showing an example valve. 
         FIG.  47    is a transverse cross-sectional view showing an example valve. 
         FIG.  48    is an exploded perspective view showing an example knob sensor. 
         FIG.  49    is a perspective view showing an example knob sensor board. 
         FIGS.  50  and  51    are the sectional views showing example operations of the valve assembly. 
         FIG.  52    is a longitudinal sectional view showing an example operation and supporting structure of the knob assembly. 
         FIG.  53    is a rear view showing the example knob ring. 
         FIG.  54    is a transverse cross-sectional view showing an example coupling state of knob ring of the knob assembly. 
         FIGS.  55  and  56    are views showing example operations of the knob ring. 
         FIG.  57    is a perspective view showing an example state in which the knob of the knob assembly is separated. 
         FIG.  58    is a transverse cross-sectional view showing an example state in which an example knob is separated from the knob assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the implementations of a fire power controlling knob assembly and a cooking appliance including the same according to the present disclosure will be described in detail with reference to the accompanying drawings. For convenience of explanation, the thicknesses of the lines and the size of the component shown in the drawings may be shown with exaggerated for clarity and convenience of explanation. In addition, the terms described below are the terms defined in consideration of a function of the present disclosure, which may vary depending on an intention or custom of the user and the operator. Therefore, the definition of these terms should be based on the contents throughout this specification. 
       FIG.  1    is a view showing an example of a composite cooking appliance having a general timer function. 
     The illustrated cooking appliance is a composite cooking appliance  1  including an oven and a cooktop. 
     The composite cooking appliance  1  may include a fire power controlling knob  2  for controlling the fire power of the cooking appliance on the front upper portion, a timer knob  3  for setting the timer time, a display device  4  for displaying various states of the cooking appliance, and a switch  5  for separate operation. 
     In the case of the cooking appliance such as an oven or a grill, since there are many cases that a long time operation is required, a timer is almost necessarily installed. 
     A fire power controlling knob  2  and the timer knob  3  perform different functions from each other, but have the advantage of being able to display a firepower or time through the amount of rotation. For unity of design and convenience of operation, it is general that knobs having the same outer shape are provided as a form arranged side by side. 
     In addition, the display device  4  serves to display an operation state of the cooking appliance, etc. Information displayed on the display device  4  may be an output (or temperature) of a burner, a timer time, a cooking of the automatic cooking function, etc. 
     However, when the number of burner provided with the timer function is increased, the number of the timer knob  3  has to be also increased, so that the problem that the front surface shape of the cooking appliance  1  becomes complicated is generated. In addition, a concern of confusing as to which timer knob  3  that performs cooking at the same time in various burners will indicate the cooking time of which burner. 
       FIG.  2    is a view for explaining a generation of position error of the fire power controlling knob. 
     As shown, the burner provided in the cooking appliance has a valve assembly  8  for controlling a gas supply amount, and the valve assembly  8  is operated by a knob  2  exposed to the front surface of a front panel  10  and adjusts the gas supply amount provided to the burner. 
     The connection between the valve assembly  8  and the knob  2  is made by a valve shaft  9  installed to connect between the valve assembly  8  and the knob  2 . When the knob  2  is turned in a state the connection between the valve assembly  8  and the knob  2  is made, this rotational force is transmitted to the valve assembly  8  through the valve shaft  9 , thereby operating the valve assembly  8 . 
     The opening and closing amount of the valve is controlled by the operation of the valve assembly  8  made as described above. 
     The knob  2  and a knob ring  6  that annularly surrounds the periphery of the knob  2  are exposed to the appearance of the front panel  10 . 
     The knob  2  is rotatably installed in the left and right direction and the valve shaft  9  is rotatably coupled in connection with the rotation of the knob  2 . The valve shaft  9  having one side in the axial direction coupled to the knob  2  is rotated in connection with the rotation of the knob  2  and the rotational force transmitted through the valve shaft  9  is a power for the operation of the valve assembly  8 . 
     In some examples, the valve assembly  8  is manufactured by a welding method on a casting. Thus, in the manufacture of the valve assembly  8 , the valve shaft  9  has a positional tolerance. This tolerance of the valve shaft  9  results in a positional deviation of the knob  2  which is eventually assembled to the valve shaft  9 . Further, the positional deviation of the knob  2  becomes larger as the length of the valve shaft  9  becomes longer. 
     That is, the tolerance of the valve shaft  9  is directly connected by the assembly tolerance of the knob  2  and the knob ring  6  assembled to the valve shaft  9 . 
     In the figure, the correct assembled positions the knob  2  and the knob ring  6  are the positions indicated by dotted lines. However, when the tolerance of the valve shaft  9  is generated as indicated by a solid line, the assembled position of the knob  2  and the knob ring  6  is changed as indicated by the solid line. 
     A single cooking appliance may include a plurality of burners. In some cases, the knob  2  and the knob ring  6  connected to the respective valves needs to be arranged with a predetermined alignment. In some cases, due to a tolerance in each of the valve shaft  9 , the alignment the knob  2  and the knob ring  6  may be externally misaligned, thereby degrading the appearance quality. 
     In some examples, the tolerance of the valve shaft  9  not only causes a simple appearance defect, but also causes an operation defect. The rotation operation of the knob  2  is not smoothly made due to the misalignment of the valve shaft  9  and it causes the defect which is not returned since the knob  2  is fitted. 
     The present disclosure is provided so as to improve the appearance quality of the cooking appliance and reduce the operation defect of the knob  2  by assembling the knob  2  and the knob ring  6  at a correct position, in order to resolve the above-mentioned problem. 
       FIG.  3    is a perspective view showing a state in which the fire power controlling knob assembly in accordance with an exemplary implementation of the present disclosure is assembled into a front panel,  FIG.  4    is a perspective view showing by removing a front panel from  FIG.  3   ,  FIG.  5    is a perspective view showing a state which a fire power controlling knob assembly in accordance with an exemplary implementation of the present disclosure is separated into 3 portions,  FIG.  6    is a perspective view of the knob assembly of  FIG.  4    viewed from the rear side, and  FIG.  7    is a side view of the knob assembly of  FIG.  4   . 
     As shown, the fire power controlling knob assembly in accordance with an exemplary implementation of the present disclosure includes a case assembly  100  assembled to the front panel  10 , a valve assembly  300  fixed in the cooking appliance, a joint  200  connecting a knob shaft ( 116  of  FIG.  8   ) of the case assembly  100  and the valve shaft ( 330  of  FIG.  5   ) of the valve assembly  300 . 
     In addition, a knob sensor  400  for sensing a rotation angle of the knob shaft  116  is arranged on the valve assembly  300  and a knob ring sensor  500  for sensing the rotation of the knob ring  120  is arranged on the case assembly  100 . 
     The case assembly  100  includes a knob  110  and a knob ring  120  which are exposed to the outside the front panel  10 . Inside of the case assembly  100 , a support frame  150  is coupled. The support frame  150  is directly fastened to the front panel  10  and the other components of the case assembly  100  have the structure coupled to or supported by the support frame  150 . 
     The knob  110  serves to control an ignition and firepower of the burner. The knob  110  is operated in such a manner that it is rotated while being pushed. Therefore, the knob  110  has to be movable in the front and rear direction of the front panel  10 . Hereinafter, the frontward and rearward working distance of the knob  110  is referred to as a front and rear direction stroke. 
     Since the knob  110  has frontward and rearward stroke, the knob  110  has to be spaced from the front panel  10  by a spacing corresponding to the forward and rearward strokes in a state of an external force is not applied. Such spacing of the knob  110  adversely affects the appearance quality. 
     The original knob ring  120  has begun to be applied for the purpose of covering that the knob  110  is separated from the front panel  10 . The knob ring  120  is fixed to the front panel  10  so as to surround the periphery of the knob  110  not to be exposed for the spacing of knob  110  from the front panel  10 . Thus, the knob ring  120  had a structure fixed to the front panel  10 , unlike the knob  110 . 
     As a result, the knob ring is fixed to the front panel  10 , and the knob  110  is the structure fixed to the valve shaft inside the cooking appliance. In such a structure, when a position error occurs in the valve shaft, it had a problem that the knob  110  is not arranged in a centering. 
     In order to solve such problem, the methods have been attempted to support the knob  110  so that it can be arranged at the center of the knob ring  120 . However, in this case, when an error occurs in the valve shaft, the knob is excessively rubbed with the knob ring, or the valve shaft is excessively rubbed at the support member, resulting in a result that the operation of the knob is not smooth. 
     In order to solve such a problem, the present disclosure provides that the fire power controlling knob assembly is divided into three portions, and the joint  200  is arranged between the case assembly  100  and the valve assembly  300 , so that the joint absorbs the positional error and secures operation performance of the knob  110 . 
     In addition, according to the present disclosure, the knob ring  120 , which had a character of an ornament for improving a conventional appearance quality, can perform a function as an operation switch for timer setting. In addition, it is characterized in that a display device  125  may be arranged on the knob ring  120  so that the set timer time can be displayed through the display device  125  arranged on the knob ring  120 . 
     At this time, the display device  125  attached to the knob ring  120  may display an intensity of the fire power together with the timer time. A display cover is provided outside the display device  125 , but a detailed assembly structure of the display device  125  will be described later. In the shown drawings, a reference numeral of the display device is displayed at a position corresponding to the position of the display device  125 . 
     The display device  125  is arranged at the upper center of the knob ring  120 . In addition, the display device  125  is arranged in an inclined form toward the upper portion so that it can be arranged to keep at a state close to right angle from the display device  125  and a view of the user, when the user positioned forward the cooking appliance views the display device  125 . It results in an effect of improving a visibility of the display device  125 . 
     This arrangement results in an effect of making it easy to identify the timer time displayed on the display device  125  during an operation of the knob ring  120 . The user turns to the left or right of the knob ring  120  and set the timer time. In this operation process, it results in an effect that the display device  125  is not covered by the user&#39;s hand. 
     The valve assembly  300  is assembled to a gas pipe  30  and a gas pipe frame  35 , which are fixed inside a cooking appliance body. 
     In the assembly process of a product, it is made by the method that the front panel  10  is assembled after manufacturing the cooking appliance body. When the gas pipe  30  and the gas pipe frame  35  are assembled to the cooking appliance body, the valve shaft  330  is fixed to the cooking appliance body. 
     In this state, after assembling the joint  200  to the valve shaft  330  and finally, the front panel assembled with the case assembly is assembled to the cooking appliance, main body and the knob shaft  116  is fitted into the joint  200 , and the assembly is coupled. 
     The joint  200  absorbs the position error between the knob shaft  116  and the valve shaft  330  and serves to transmit a rotation and pushing of the knob shaft  116  to the valve shaft  330 . Therefore, since the error of the valve shaft  330  is not transmitted to the knob  110 , it is possible to reduce the position error of the knob  110  and secure operation performance of the knob  110 . 
     Conventionally, it has the structure that the knob is directly assembled to the valve shaft, so that the position error generated in the valve shaft is transferred directly to the knob, as itself, that is exposed to the appearance, and it has a problem of degrading the appearance quality of the cooking appliance. 
     In some implementations, the knob assembly of the present disclosure is assembled with a state that the knob  110  aligned with regard to the front panel  10 , and the position error of the valve shaft  330  is absorbed in the joint  200 , and thus, the knob  110  does not transfer the position error of the valve shaft  330  even when the position error is generated due to an assembly tolerance in the valve shaft  330  because the position error of the valve shaft  330  is absorbed in the joint  200 . 
     This is because the knob  110  is independently assembled at an aligned position with regard to the front panel  10  and then connected to the valve shaft  330  inside the cooking appliance by the joint  200 . 
       FIG.  8    is a perspective view showing a knob arranged at an outermost portion of the case assembly,  FIG.  9    is a perspective view showing a rear surface of the knob in  FIG.  8   , and  FIG.  10    is a perspective view showing a state in which a knob back plate shown in  FIG.  8    is separated. 
     In some examples, the knob  110  has the structure directly fitted to the valve shaft  330 , but it is characterized in that the knob  110  of the knob assembly according to the present disclosure provides the knob shaft  116  separately when the valve shaft  330 . As described above, the knob shaft  116  is connected to the valve shaft  330  through the joint  200 . 
     The knob  110  includes a knob body  112  that forms an appearance, a knob back plate  114 , and a knob shaft  116 . The knob body  112  and the knob shaft  116  may be integrally formed as a single portion and may be manufactured as separate portions and then coupled. 
     In some implementations, the knob shaft  116  may be made of a metal material for high strength and reliability. The knob body  112  may be manufactured of an injection portion forming the appearance, but a metal material processed goods is used in the case of an expensive product group. 
     In some examples, when the portion integrally made of the knob body  112  and the knob shaft  116  is manufactured through the metal processing, the time and cost required for manufacturing the portions become excessive. In order to manufacture the metal part having such a shape, a cutting processing is generally. However, since the size of a raw material for cutting processing is increased, there are many the cut scraps, thereby increasing the processing time and the processing unit cost. 
     However, even when the knob body  112  and the knob shaft  116  are the same metal material, the processing cost may be lowered when separately manufacturing it, and coupling it. In this case, the knob body  112  is manufactured by cutting processing, and the knob shaft  116  is applicable to a method of manufacturing a wire material such as rolling, etc. 
     At this time, the coupling between the knob body  112  and the knob shaft  116  can use the method of a shrinkage fitting, an indentation, and a welding, etc. 
     In some examples, the knob back plate  114  coupled to the rear surface of the knob body  112  is advantageous from the viewpoint of cost using a molding portion because it is less exposed externally and has a complicated shape. 
     The knob back plate  114  functions in order for not to be operate the knob  110  in a state without pushing the knob  110  together with a locking bracket ( 140  of  FIG.  11   ) described later. 
     The knob back plate  114  provides a guide surface  114   c  extending to the center side of the knob shaft  116  and the guide surface  114   c  provides a cutting section  114   b  at the portion corresponding to the position of the locking bracket  140  when the knob  110  is in the origin position (the position in an off state). 
     In other words, when the knob is not pushed when the knob  110  is in the off state, the locking piece ( 142  in  FIG.  14   ) of the locking bracket is positioned inside the cutting section  114   b , one side of the guide surface  114   c  becomes an engaging surface  114   d  and interferes with the locking bracket  140 , and thus, a user may not rotate the knob  110 . 
     When the knob  110  is pushed, the engaging surface  114   d  becomes a position corresponding to a knob passage groove  144  provided in the locking bracket  140 , and the engaging surface  114   d  passes through the knob passage groove  144  and it is in a state of being able to rotate. Accordingly, in a state which the knob  110  is pushed, the knob  110  can be rotated. 
     General push and turn type knobs have a structure in which the knob  110  itself can rotate even in a state which the knob is not pressed, but the rotational force of the knob  110  is not transmitted to the valve. The present disclosure provides a structure which cannot be rotated even for the knob  110  in a state the knob  110  is pushed by using an interference of the locking bracket  140  and the knob back plate  114 , as described above. 
     In some examples, the engaging surface  114   d  defined on the guide surface  114   c  of the knob back plate  114  may be aligned with the locking bracket  140 , and the locking bracket  140  may be aligned with the origin position of the knob body  112 . Accordingly, the knob body  112  and the knob back plate  114  may be constrained and may not rotate with regard to each other. 
     In some implementations, the knob back plate  114  may be fastened to the knob body  112  through the fastening hole  114   a . Although the shown knob body  112  is shown as a straight handle shape, it may be formed simply as a conical shape, and may have a shape in which the origin position is engraved or colored, and a knob design having various other shapes may be applied in addition to that. 
     Hereinafter, all configuration of the case assembly except the knob will be described. 
       FIG.  11    is a view showing the separated state of all configurations of the case assembly,  FIG.  12    is a view showing a separated state of the configurations arranged inside the front panel of the case assembly,  FIG.  13    is a view showing a state which the configurations inside the front panel of the case assembly is arranged, and  FIG.  14    is a view showing a separated state of the configurations arranged to the outside the front panel of the case assembly, and  FIG.  15    is a view showing a state which the configurations arranged outside the front panel of the case assembly are assembled. 
     As shown, the case assembly  100  includes the knob ( 110  of  FIG.  8   ), the knob ring  120 , a spacing plate  130 , the locking bracket  140 , the support frame  150 , a spacing pipe  160 , an actuating member  170 , a fixed frame  180 , and a fixed pipe  190 . 
     Among them, the knob  110 , the knob ring  120 , the spacing plate  130 , and the locking bracket  140  are arranged outside the front panel  10 . 
     The support frame  150 , the spacing pipe  160 , the actuating member  170 , and the fixed frame  180 , and the fixed pipe  190  are arranged inside the front panel  10 . 
     The present disclosure provides the structure which the knob ring  120  provided in the case assembly  100  is rotatable in both directions in a predetermined range and includes a knob ring sensor  500  of sensing the rotation of the knob ring  120 . In addition, a knob sensor  400  for sensing the amount of rotation of the knob  110  to be described later is arranged in the valve assembly  300  and connected to the valve shaft  330 . 
     The knob ring  120  includes a knob ring body  122 , a knob ring back plate  124 , a display device  125 , a display housing  126 , and a display cover  127 . 
     The knob ring body  122  forms the appearance of the knob ring  120  and serves to fix the display device  125 . The display housing  126  secures insulating performance of the display device  125 , which is an electronic component, and secures to be fastened to the knob ring body  122 . The display cover  127  together with the knob ring body  122  forms the appearance of the knob ring  120 . 
     The knob ring body  122  may be made of a metal material similar to the knob body  112 . Since the knob ring body  122  is a portion which the user&#39;s hand has to be continuously contacted like the knob body  112 , a metal material may be used for improving a sensitive quality, improving the appearance quality, and improving a durability. 
     The display cover  127  is coupled as a form of surrounding the outer surface of the display device  125  and the display housing  126  received therein. The display cover  127  may be made of a semi-translucent material so that only information displayed on the display device  125  can be viewed while the inner component is not visible to the outside. 
     Here, the translucency may be a degree of transmitting of a portion of a light emitted from a display, and does not mean of limiting the range of a predetermined translucent ratio. 
     The display device  125  is coupled to the display housing  126  and the display housing  126  coupled with the display device  125  is coupled to the knob ring back plate  124 , and then, the knob ring back plate  124  coupled with the display housing  126  is coupled to the knob ring body  122 . 
     In some implementations, the display housing  126  and the knob ring body  122  may provide the groove and the protrusion at positions corresponding to each other, so that the display housing  126  can be assembled at an aligned position with regard to the knob ring body  122 . 
     The display cover  127  which forms the appearance of the knob ring  120  together with the knob ring body  122  is a structure which is fitting coupled to the knob ring body  122  in a state which the knob ring body  122  and the knob ring back plate  124  are fastened. 
     In some examples, a spacing plate  130  is arranged between the knob ring back plate  124  of the knob ring  120  and the front panel  10 . The spacing plate  130  is a kind of thrust bearing and serves not to directly rub the knob ring  120  and the front panel  10 , and maintain the predetermined spacing between the knob ring  120  and the front panel  10 . 
     It is possible to set the spacing between the rear surface of the knob ring  120  (the rear surface of the knob ring back plate) and the outer surface of the front panel  10  by adjusting the thickness of the spacing plate  130 . 
     The spacing plate  130  may be made of a material having a low coefficient of friction such as Teflon, and a lubricant having viscosity may be applied to the surface of the spacing plate  130 . 
     The configuration which is directly fastened to the front panel  10  of the external configurations of the front panel  10  is the locking bracket  140 . The locking bracket  140  serves not to rotate without pushing the knob  110  in Push &amp; Turn method. 
     The locking bracket  140  is directly fastened to the front panel  10  through a bracket hole  124   b  provided in the knob ring back plate  124 . 
     Since the knob ring back plate  124  rotates in both directions together with the knob ring  120 , the bracket hole  124   b  is formed as an arc long hole in the knob ring back plate  124 . It is such that the knob ring back plate  124  is rotated in a state which the locking bracket  140  is fastened to the front panel. 
     In addition, the spacing plate  130  is closely attached to the outer surface of the front panel  10 . In the shown implementation, the spacing plate  130  is provided with a bracket groove  132  at a portion corresponding to the fastening position of the locking bracket  140 . 
     It is for the locking bracket  140  to be directly attached to the surface of the front panel  10  and fastened. However, since the spacing plate  130  does not rotate with the knob ring but maintains the fixed position, it is sufficient that the bracket groove  132  is formed to have a size corresponding to the fastening surface of the locking bracket  140 . 
     Of course, as another implementation, the locking bracket  140  may be fastened to the front panel through the spacing plate  130 . In this case, the spacing plate  130  may be provided with a fastening hole which can be extension formed to the portion corresponding to the fastening surface of the locking bracket  140  and can penetrate a fastening vole S 3  for fastening the locking bracket  140 . The locking bracket  140  can be repeatedly applied with a lateral force, and the fixing of the center position is important. In some implementations, the locking bracket  140  may be fastened to the front panel  10  with at least two fastening bolts S 3 . 
     In some examples, the front panel  10  is provided with a wiring hole  12  for passing through the wiring connected to the display device  125 . The wiring hole  12  is for passing the wiring that supplies power and a signal to the display device  125 . The display device  125  is fixed to the knob ring  120  and rotates together with the knob ring  120  so that the wiring is rotated together with the knob ring  120 . Therefore, the wiring hole  12  is formed as an arc-shaped long hole. 
     The support frame  150 , the spacing member  160 , the actuating member  170 , the fixed frame  180 , the fixed pipe  190 , and the knob ring sensor  500  of  FIG.  12    are arranged inside the front panel  10 . 
     The support frame  150  is directly fastened to the front panel  10  through the fastening bolt S 1  penetrating through the front panel  10  in a state which is arranged on the inner surface of the front panel  10 . The head of the fastening bolt S 1  is inserted into the bolt receiving hole  133  of the spacing plate  130  to serve as a fixing protrusion for fixing the position of the spacing plate  130 . 
     The support frame  150  provides a pair of spring fixing portions  155  to which the restoring springs  156   a  and  156   b  of providing the restoring force of the actuating member  170  are fixed. In addition, a restoring magnet  158  is fixed to the support frame  150  so that the actuating member  170  can have a fixing force at the origin. 
     The actuating member  170  is fitted inside the support frame  150  and then is fastened to the knob ring  120  through a fastening bolt S 2 . Thus, the actuating member  170  can rotate integrally with the knob ring  120 . The actuating member  170  provides the spring fixing portion  175  to which the restoring spring  156   a ,  156   b  is fixed. The spring fixing portion  175  of the actuating member  170  is arranged between the spring fixing portions  155  of the support frame  150  and they are connected by a pair of restoring spring  156   a ,  156   b.    
     When the knob ring  120  is rotated to one side, it is configured such that one restoring spring is tensioned and the other restoring spring is compressed. When the external force applied to the knob ring  120  is released, it is configured such that the knob ring  120  can be returned to the origin position by the elastic force of the restoring spring  156   a ,  156   b.    
     In addition, the actuating member  170  is provided with a restoration magnet  178  paired with the restoration magnet  158  of the above-mentioned support frame  150 . The restoring magnet  158  arranged in the support frame  150  and the restoring magnet  178  arranged in the actuating member  170  are arranged at a position corresponding to each other such that the knob ring  120  is the closest position in a state which it is located at the origin. 
     In the illustrated implementation, four fastening bolts S 2  are applied to firmly fasten the actuating member  170  having a cylindrical shape and the knob ring back plate  124 . However, three fastening bolts S 2  can be fastened at a spacing of 120°. 
     In some examples, the actuating member  170  is partially protruded from the front surface of the front panel  10  through the support frame  150  so as to be in direct contact with the knob ring back plate  124  and can be fastened. This is to make the actuating member  170  protruding outside the front panel  10  support the knob ring back plate  124 . 
     The actuating member  170  includes an operating portion  171  inserted into the support frame  150 , a support portion  172  formed in a flange shape at the inner end of the operating portion  171 , and an extended portion  173  from both sides of the support portion  172  to the outside. A spring fixing portion  175  is provided on the extended portion  173  on one side. 
     In addition, the extended portion  173  is provided with a magnet groove  177  into which the restoring magnet  178  is inserted. The restoration magnet  178  fixed to the actuating member  170  is arranged so as to generate a magnetic force in a direction closely attached to the restoring magnet  178  fixed to the support frame  150 . It is for the actuating member  170  to be fixed by the attaching power of the restoring magnets  158 , 178  at the origin position. 
     In addition, the outer circumferential surface of the actuating member  170  operates by the rubbing with the inner surface of a support frame through hole  151  of the support frame  150 . 
     In some examples, the spacing member  160  is made of Teflon, etc. having a low coefficient of friction like the spacing plate  130  and inserted between the outer circumferential surface of the actuating member  170  and the inner circumferential surface of the support frame through hole  151 . The spacing member  160  may be formed in a cylindrical shape which one surface is cut so as to have a variable diameter. 
     In the case of the illustrated implementation, the spacing plate  130  and the spacing member  160  are shown as separate portion. However, the spacing plate  130  and the spacing member  160  are made of the same material such as Teflon having a low coefficient of friction and they may be integrally formed as a single part because there are the portions which are in contact with each other. 
     In addition, a lubricant (for example, grease) for reducing the rubbing and the noise can be applied to the surface of the spacing plate  130  and the spacing member  160 . 
     The fixed frame  180  secures to support the rear surface of the actuating member  170  to prevent the actuating member  170  from being pushed and entered into the inside of the front panel. 
     The fixed frame  180  may be provided for convenience of the assembly. The actuating member  170  has to be fastened to the knob ring  120  as described above. When the fixed frame  180  is not provided, a fastening work has to be performed in a state when the knob ring  120  and the actuating member  170  are fixed by hands or a tool. 
     However, when the fixed frame  180  is provided, when the actuating member  170  is inserted into the support frame  150  and the fixed frame  180  is fastened to the rear surface of the actuating member  170 , the actuating member  170  cannot deviate from the support frame  150 . Therefore, when the knob ring  120  is assembled, the knob ring  120  is aligned to the actuating member  170  on the front side of the front panel, and then the fastening operation can be performed, and thus, workability is improved. The fixed frame  180  has a rotatable region  182  that defines a rotation angle of the extended portion  173  of the actuating member  170 . 
     In addition, since the actuating member  170  is integrally rotated with the knob ring  120 , the knob ring sensor  500  senses the knob ring sensor magnet  530  fixed to the actuating member  170  and can recognize the operation of the knob ring  120 . 
     The knob ring sensor  500  is fastened to the support frame  150  directly fastened to the front panel  10 . Since the knob ring sensor  500  is sufficient to be fixed at a position close to the actuating member  170 , it may be fastened to the fixed frame  180  or directly fastened to the front panel  10 , depending on the shape. 
     In addition, a fixed pipe  190  is fastened to the rear surface of the fixed frame  180 . The fixed pipe  190  serves to support the knob shaft  116  provided on the knob  110  and guide the assembly of the joint  200 . 
     Referring to  FIG.  14   , the head of the fastening bolt  51  of fixing the support frame  150  and the front panel  10  is a state exposed on the outer surface of the front panel  10 . An appearance exposure of the fastening bolt S 1  results in a degradation of the appearance quality. 
     In some examples, in order to make the knob ring  120  rotate in both directions, a gap may be defined between the knob ring  120  and the front panel  10 . 
     As described above, the gap between the knob ring  120  and the front panel  10  can be secured by the spacing plate  130 . In addition, the present disclosure provides a structure in which the spacing plate  130  surrounds the support frame fastening bolt S 1  to which the appearance is exposed, so that the fastening bolt S 1  is not externally exposed. 
     Of course, since the knob ring  120  is arranged on the front surface of the fastening bolt S 1 , the fastening bolt S 1  is not exposed on the front surface. However, when the user views it from the side, this is because that the fastening bolt S 1  can be viewed through a gap (a gap for the rotation of the knob ring) between the knob ring  120  and the front panel  10 . 
     For this, the spacing plate  130  is provided with a bolt receiving hole  133  at a position corresponding to the support frame fastening bolt S 1 . In addition, the spacing plate  130  has a through hole  135  at the center and an inner circumferential surface of the through hole  135  has the surface of being supported by the actuating member  170  protruding to the outside the front panel  10 . 
     Therefore, the spacing plate  130  may not require separate fastening. This is because the knob ring  120  which is closely attached to the front surface of the spacing plate  130  is fastened to the actuating member  170  with the front panel  10  therebetween. 
     Next, the assembly structure of the knob ring  120  will be described in more detail. 
       FIG.  16    is a perspective view showing an appearance in a state which the knob ring is assembled, and  FIGS.  17  and  18    are the exploded perspective views for explaining an assembling structure of the knob ring. 
     As shown, the knob ring body  122  has a ring shape surrounding the rear surface of the knob, and the remaining portions except the portion penetrating through the knob shaft  116  at the center are covered by the knob ring back plate  124 . 
     The knob ring body  122  has a protruding portion  122   a  that covers both sides of the display device  125  on the upper side. The protruding portion  122   a  provides a structure for fixing the display device  125  while securing to protect the side of the display device  125 . In addition, the protruding portion  122   a  of the knob ring body  122  can be used as a handle when the user operates the knob ring body  122 . 
     When rotating a circular product, the force to rotate only through the frictional force of the surface is transmitted. There are many cases that it is not easy to secure a frictional force in a kitchen environment having many cases that a lot of water is used and the gloves are used by wearing. 
     In this case, when the protruding portion  122   a  is on one side of the ring shape, by pushing it, the protruding portion in the rotating direction, the rotating force can be transmitted. For example, when the knob ring  120  is to be rotated in clockwise, the side of the left protruding portion  122   a  may be pressed to the right side. In some examples, when the knob ring  120  is to be rotated counterclockwise, the side of the right protruding portion can be pressed to the left. 
     The knob ring body  122  provides a knob ring back plate  124  and a fastening hole  122   h  for fastening. Although four fastening holes  122   h  are provided for firm and accurate fastening of the shown implementation, the number of fastening holes  122   h  may vary depending on the fastening structure, the size of the knob ring  120 , etc. 
     When the protruding portion  122   a  is provided on the upper part of the knob ring body  122  and the display device  125  is inserted therebetween, both sides and the bottom surface of the display device  125  are surrounded by the knob ring body  122 . In addition, the display cover  127  is coupled in a form of covering the upper surface of the display device  125  and the rear surface of the display device  125  is coupled to the knob ring back plate  124 . As a result, all of six sides of the display device are wrapped, and provide the structure which the display device  125 , which is vulnerable to moisture and impact, can be securely coupled to the knob ring  120 . 
     A protrusion  122   a  and a groove  122   b  for constraining the display housing  126  to a center position are provided inside the protruding portion  122   a  of the knob ring body  122 . 
     The knob ring body  122  may be made of a metal material like the knob body  112 . The knob body  112  and the knob ring body  122  are the portions exposed to the appearance, and are the portions which the user&#39;s hands are repeatedly contacted and may be manufactured of a metal material for improving durability and appearance quality. 
     In some examples, the knob ring body  122  is fastened to the knob ring back plate  124  and the fastening bolt S 5  is fastened at the knob ring back plate  124  side. It is for the fastening bolt S 5  not to be exposed to the appearance, thereby resulting in an effect of improving the appearance quality. 
     The rear surface of the knob ring back plate  124  provides an inner circular plate area  124   j  in which the actuating member  170  is received and a donut-shaped outer circular plate area  124   k  formed outside the inner circular plate area  124   j . A spacing plate  130  is received inside the outer circular plate area  124   k.    
     The side of the inner circular plate area  124   j  surrounds and supports the outer circumferential surface of the actuating member  170  while the side of the outer circular plate area  124   k  surrounds and supports the outer surface of the spacing plate  130 . Such a structure provides a structure that allows the knob ring  120  to stably rotate in both directions at the center position. 
     The spacing between the knob ring back plate  124  and the front panel  10  can be adjusted by adjusting the thickness of the spacing plate  130  and the recessed depth of the outer circular plate area. 
     For example, when the thickness of the spacing plate  130  is set to be 0.2 mm larger than the recessed depth of the outer circular plate area  124   k , the spacing between the knob ring back plate  124  and the case is set to 0.2 mm. 
     This serves to prevent a scratch from being generated on the surface of the front panel  10  by directly rubbing to the knob ring back plate  124  on the surface of the front panel  10 . Since the knob ring back plate  124  has a shape in which the upper portion arranged with the display device  125  is protruded, when the scratch is generated in this portion, even when the knob ring is in the origin position, the scratch portion can be exposed externally to left and right. 
     The display device  125  is fastened to the knob ring back plate  124 . The display device  125  is provided with a fastening hole  125   d  and the knob ring back plate  124  is provided with a fastening hole  124   e  at a position corresponding to the fastening hole  125   d  of the display device  125 . 
     In addition, the display housing  126  coupled to the display device  125  has a fastening boss  126   d  at a position aligned with the fastening holes  124   e  and  125   d . A fastening bolt S 4  inserted in the knob ring back plate  124  sequentially passes through the fastening hole  124   e  of the knob ring back plate  124  and the fastening hole  125   d  of the display device  125 , and then, is fastened to the fastening boss  126   d  of the display housing  126 . The knob ring back plate  124 , the display device  125 , and the display housing  126  are integrally fastened through the fastening bolt S 4 . 
     In other words, the fastening is made in a state that the display device  125  is fitted between the knob ring back plate  14  and the display housing  126 . As described above, the knob ring body  122  may be made of a metal material. In order to prevent the display device  125  included with an electronic circuit from being a short circuit with the knob ring body  122 , the display housing  126  may be made of an insulating material. Through this, stable operation performance of the display device  125  can be secured. 
     The display housing  126  may be formed as a frame form that surrounds the outer circumferential surface of the display device  125 . 
     In addition, the fastening boss  126   d  of the display housing  126  forms the guide protrusion  126   b  to the front side of the display housing  126 . The guide protrusion  126   b  is inserted into the receiving groove  122   b  provided on the rear surface of the protruding portion of the knob ring body  122  to provide a structure in which the display housing  126  can be coupled in a state aligned with the knob ring body  122 . 
       FIG.  19    is a perspective view showing a display device, and  FIG.  20    is a perspective view showing a rear surface of a display device of a knob assembly according to the present disclosure. 
     As shown, the display device  125  of the knob assembly according to the present disclosure includes a display board  125   b  and a display module  125   a . A connector  125   c  is provided on the rear surface of the display board  125   b . In addition, the display board  125   b  is formed larger than the display module  125   a  to the both sides. The display board  125   b  exposed to both sides of the display module  125   a  is provided with a fastening hole  125   d.    
     The above described knob ring back plate  124 , the display device  125 , and the display housing  126  are fastened through the fastening hole  125   d . The display module  125   a  may be configured to be of a type that the light is emitted. 
       FIG.  21    is a perspective view showing a display housing, and  FIG.  22    is a perspective view showing a rear surface of a display housing. 
     The display housing  126  has a frame shape that surrounds the outer surface of the display device  125 . The display housing  126  is coupled in a form of fitting with the display device  125 , and the knob ring back plate  124  is fastened having the display device  125  therebetween by the fastening volt S 4 . 
     The display housing  126  includes a frame portion  126   f  surrounding the display module  125   a  of the display device  125  and a wing portion  126   w  surrounding the display board  125   b.    
     The display housing  126  may be manufactured by a method of injection molding with a material having an insulating material. Insulation performance of the display housing  126  may provide protection for the display device  125  that includes electronic components. 
     The display housing  126  fixes the display device  125  and is coupled to the knob ring body  122 . 
     The coupling of the display housing  126  and the knob ring body  122  is a structure for allowing the display housing  126  to be fixed in the center position with regard to the knob ring body  122  by a fitting coupling structure. 
     The display housing  126  is fastened to the knob ring back plate  124  by the fastening volt S 4  having the display board  125   b  of the display device  125  therebetween and is not substantially fastened to the knob ring body  122 . In addition, since the knob ring back plate  124  is fastened to the knob ring body  122 , the display housing  126  has the structure of fastened to the knob ring body  122  through the knob ring back plate  124 . 
     Since the display housing  126  is not directly fastened to the knob ring body  122 , a structure for a position alignment with regard to the knob ring body  122  of the display housing  126  is needed. 
     For this, the present disclosure includes a guide protrusion  126   b  on the front surface of a wing portion  126   w  of the display housing  126 , and provides a guide groove  126   c  on a side. 
     In addition, a front support portion  126   a  is provided on the forward side of the frame portion  126   f  The front support portion  126   a  is protruded in a form of blocking the through hole exposed with the display device  125  and supports the front surface of the display module  125   a , thereby serving to prevent the front surface of the display module  125   a  from being protruded at the display housing  126 . 
     Referring to the rear surface of the display housing  126 , the fastening boss  126   d  is provided. The fastening bolt S 4  fastened through the knob ring back plate  124  is fastened to the fastening boss  126   d . The fastening boss  126   d  is connected to the guide protrusion  126   b  on the front surface of the display housing  126  on a straight line. In other words, the fastening hole of the fastening boss  126   d  is connected to the inside the guide protrusion  126   b.    
     In addition, a rear support portion  126   e  is provided on the rear surface of the frame portion of the display housing  126 . The rear support portion  126   e  is supported on the front surface of the knob ring back plate  124  contacting with the rear surface of the display housing  126 , thereby securing to prevent the knob ring back plate  124  from entering inside the display housing  126 . 
       FIG.  23    is a perspective view showing a rear surface of a knob ring, and  FIGS.  24  and  25    are the views for explaining a coupling structure of the display device and the knob ring of the knob assembly according to the present disclosure. 
     As shown, the knob ring body  122  is provided with a pair of protruding portion  122   a  at an upper portion. A display is coupled between the protrusion  122   a.    
     The display device  125  is constrained to the knob ring body  122  through the display housing  126  described above. 
     The receiving groove  122   b  to which the guide protrusion  126   b  of the display housing  126  is provided inside the protruding portion  122   a  of the knob ring body  122  and the guide rail  122   c  to which a guide groove  126   c  of the display housing  126  is inserted is provided to the inner side of the protruding portion  122   a.    
     As shown, the display housing  126  has the structure which is fitting coupled between the protruding portion  122   a  of the knob ring body  122  in a state of fitting the display device  125  to the display housing  126 . 
     When the guide protrusion  126   b  of the display housing  126  is inserted into the receiving groove  122   b  of the knob ring body  122 , it can prevent the up and down and left and right flow of the display housing  126 . 
     In addition, the guide rail  122   c  of the knob ring body  122  is inserted into the guide groove  126   c  of the display housing  126  to guide the coupling of the display housings  126  and prevent the up and down directions deviation of the display housing  126 . 
     In addition, a coupling hole  122   h  for fastening with the knob ring back plate  124  is provided on the rear surface of the knob ring body  122 . In a state which the knob ring body  122  is directly fastened to the knob ring back plate  124  and the display device  125  is fastened to the knob ring back plate  124  together with the display housing  126 , the knob ring back plate  124  is fastened to the knob ring body  122  and inserted into between the protruding protrusion  122   a  of the knob ring body  122  and fixed. 
     In some examples, the upper surface groove  122   t  is provided on the upper surface of the protruding portion  122   a  of the knob ring body  122 . The upper surface groove  122   t  is a configuration for coupling with the display cover  127 . 
       FIG.  26    is a perspective view showing a knob ring back plate,  FIG.  27    is a perspective view showing a rear surface of a knob ring back plate, and  FIG.  28    is a longitudinal sectional view of the knob ring back plate of the knob assembly in accordance with an exemplary implementation of the present disclosure. 
     As shown, the knob ring back plate  124  can be largely divided into three portion, a circular plate portion  124 - 1 , an extended portion  124 - 2 , and supporting pipe portion  124   c ,  124   f.    
     The circular plate portion  124 - 1  has a circular plate shaped outer shape, and the extended portion  124 - 2  has a shape protruded outward so as to shield the rear surface of the protrusion of the knob body. 
     The supporting pipe portion includes an outer supporting pipe  124   c  protruded toward outside of the front panel and an inner supporting pipe  124   f  protruding toward inside of the front panel. The outer supporting pipe  124   c  and the inner support pipe  124   f  are formed on the same axis, and a knob shaft insertion hole  124   d  is formed therein. 
     The circular plate portion  124 - 1  includes an inner circular plate area  124   j  having a size corresponding to the actuating member  170  again and an outer circular plate area  124   k  having a size corresponding to the spacing plate  130 . 
     The supporting pipe portion  124   c ,  124   f  is formed in a form protruded from the center of the circular plate portion  124 - 1  to both sides. The supporting pipe portions  124   c ,  124   f  serve to support the knob shaft  116  inserted therein. The knob shaft  116  and the supporting pipe portion  124   c ,  124   f  serves to mutually support. When the knob is operated, it is supported by the supporting pipe portion  124   c ,  124   f  to which the knob shaft is fixed. When the knob ring is operated, the supporting pipe portions  124   c ,  124   f  is supported by the knob shaft inserted therein. 
     The outer circular plate area  124   k  of the knob ring back plate  124  is provided with a fastening hole  124   h  for fastening with the knob body  112  and the inner circular plate area  124   j  is provided with the fastening hole  124   i  for fastening with the actuating member. Through this, the knob body  112  and the actuating member  170  are fastened with the knob ring back plate  124  as the medium. 
     In addition, the outer circular plate area  124   k  of the knob ring back plate  124  is provided with a bracket hole  124   b  through which the locking bracket penetrates and is coupled to the front panel. The bracket hole  124   b  is formed into an arc shape long hole by reflecting the rotation range of the knob ring. 
     In some examples, the inner supporting pipe  124   f  is divided into cut section  124   g  so as to have a flexibility. This is to allow the inner supporting pipe  124   f  to be smoothly assembled with other component during the assembly process. 
     The inner supporting pipe  124   f  is assembled in a form inserted inside the fixed frame  180  and the fixed pipe  190  are inserted inside, and at this time, when an outer diameter of the inner supporting pipe  124   f  is contracted, the assembly convenience can be improved. Therefore, the inner supporting pipe  124   f  is divided into the cut section  124   g  so that the outer diameter of the inner supporting pipe  124   f  can be contracted during the assembly process. 
     In some implementations, the cut section  124   g  cuts the inner supporting pipe  124   f  in the lateral direction. This results in an effect that the inner supporting pipe  124   f  can reduce the up and down external diameter in the up and down direction due to the pressure in the up and down direction during the assembling process. 
     The extended portion  124 - 2  is provided with a fastening hole  124   e  for fastening the display board  125   b  and the display housing  126  together. The fastening bolt S 4  entering from the rear surface of the knob ring back plate  124  is fastened to the fastening boss  126   d  of the display housing  126  after passing through the fastening hole  125   d  of the display board  125   b.    
     In addition, the extended portion  124 - 2  is provided with a wiring hole  124   a  through which the wiring connected to the connector  125   c  provided on the rear surface of the display board  125   b  passes. The assembling of the wiring is made after the assembly of the knob ring  120 . After assembling the knob ring  120  to the front panel, the wiring is coupled to the connector  125   c  exposed through the wiring hole  124   a.    
     The inner circular plate area  124   j  of the circular plate portion  124 - 1  has a shape protruded forward compared with the outer circular plate area  124   k . This is such that the actuating member  170  is inserted into the inner circular plate area  124   j  so that the side of the actuating member can be supported by the side of the inner circular plate area  124   j . A spacing plate  130  is received inside the outer circular plate area  124   k  so that the outer surface of the spacing plate  130  is supported by the side of the outer circular plate area  124   k.    
     The knob ring back plate  124  has a complicated shape to be fastened to other configurations, and it is advantageous in manufacturing cost aspect to manufacture by injection molding. 
       FIG.  29    is a view for explaining the assembly of the display cover of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  30    is a perspective view showing the display cover of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  31    is a half cross sectional view showing the display cover of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  32    is a sectional view showing a state before the display cover of the knob assembly in accordance with an exemplary implementation of the present disclosure is coupled, and  FIG.  33    is a sectional view showing a state which the display cover of the knob assembly in accordance with an exemplary implementation of the present disclosure is coupled. 
     As shown, the display cover  127  is configured to be coupled with the fitting coupling at the supper portion of the protrusion of the knob ring body  122  after the knob ring body  122 , the knob ring back plate  124 , the display device  125 , and the display housing  126  are assembled. 
     The display cover  127  together with the knob ring body  122  forms the appearance of the knob ring. 
     The knob ring body  122  has a slot groove  122   d  into which the insertion protrusion  127   a  formed at a lower end of the display cover  127  is fitted. The insertion protrusion  127   a  is formed at the lower end of the front surface of the display cover  127  and is inserted into the slot groove  122   d  of the knob ring body  122 . The insertion protrusion  127   a  of the display cover  127  is fitted into the slot groove  122   d  of the knob ring body  122  so that the surface of the display cover  127  aligns with the outer surface of the knob ring body  122  and is constrained. However, the insertion protrusion  127   a  is not fixed to the slot groove  122   d , and thus, the fastening force is not generated due to the coupling of the insertion protrusion  127   a  and the slot groove  122   d.    
     A pair of restraining protrusion  127   b  is provided on the upper bottom surface of the display cover  127 . The restraining protrusion  127   b  is resiliently deformed and inserted into the protruding portion  122   a  of the knob ring body  122  and then restrained by the upper inner surface of the protruding portion  122   a . The coupling force of the display cover  127  is secured by the restraining protrusion  127   b.    
     In addition, a pair of side support protrusions  127   t  are provided on both sides of the upper bottom surface of the display cover  127 . The side supporting protrusion  127   t  is fitted into the upper surface groove  122   t  provided on the upper surface of the knob ring body  122 . The pair of side supporting protrusion  127   t  is constrained to the upper surface groove  122   t  provided in the protruding portion  122   a  in both sides, respectively and aligns the coupling of the knob ring body  122  with the display cover  127 . 
     In addition, a rear surface supporting protrusion  127   c  is provided on the upper bottom surface of the display cover  127 . The rear surface supporting protrusion  127   c  supports the front surface of the knob ring back plate  124  to align the coupling of the knob ring back plate  124  and the display cover. 
     In addition, the display cover  127  has a thin walled portion  127   f  having a thickness thinner than the other portion in a portion corresponding to the display portion area of the display module  125   a.    
     In some implementations, since the display cover  127  may define the appearance, the display cover  127  may be made of a translucent material so as not to expose an inside complicated shape to the outside. By the way, the transmittance of the translucent material can be controlled by the thickness. When the portion corresponding to the display portion area of the display module  125   a  is made thinner than the other area, it is possible to reduce a change in brightness or color of light emitted from the display module  125   a.    
     Next, the structure of the joint will be described. 
       FIG.  34    is a cross section showing a state which the joint is separated from the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  35    is a perspective view showing a joint of the knob assembly in accordance with an exemplary implementation of the present disclosure, and  FIG.  36    is an exploded perspective view illustrating a joint of the knob assembly in accordance with an exemplary implementation of the present disclosure.  FIG.  37    is a longitudinal cross section showing a joint of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  38    is a transverse sectional view showing the joint of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIGS.  40  and  41    are the views for explaining a rotation operation of the joint of the knob assembly in accordance with an exemplary implementation of the present disclosure. 
     The joint  200  serves to connect the case assembly  100  and the valve assembly  300 . 
     The joint  200  is fitted to the knob shaft  116  provided in the knob and the valve shaft  330  provided in the valve assembly. 
     The joint  200  is installed between the valve shaft  330  and the knob shaft  116  and connects the valve shaft  330  and the knob shaft  116 , and it includes the joint housing  210  and the first shaft coupling portion  220 , the second shaft coupling portion  230 , a joint spring  260 , a reinforcement insert ring  240 , and a reinforcement cap  250 . 
     The joint housing  210  has a predetermined length and is formed into a cylindrical shape formed with a hollow. At one side of the longitudinal direction of the joint housing  210 , a hollow, that is, an insertion portion for opening the inner space of the joint housing  210  to the outside of the joint housing  210  is formed. In addition, a side plate portion  214  of blocking a longitudinal other side of the joint housing  210  is provided on the side facing with the insertion portion, that is, the longitudinal other side of the joint housing  210 . A through hole  214   a  for opening the inner space of the joint housing  210  to the outside of the joint housing  210  is formed in the inner side of the side plate portion  214 . 
     Also, a plurality of slots  216 ,  218  may be formed in the joint housing  210 . Each slot  216 ,  218  is formed in a long hole shape extending along the longitudinal direction of the joint housing  210  and may be formed as the long hole shape having a predetermined width extending along the circumferential direction of the joint housing  210  and the predetermined length along the longitudinal direction of the joint housing  210 . 
     According to the present implementation, the joint housing  210  is formed with a pair of first slot  216  and a pair of second slot  218 . 
     The pair of first slot  216  is formed to be penetrated to the side of the joint housing  210 , respectively, and viewed from longitudinal one side or other side of the joint housing  210 , it is arranged to face each other. 
     In addition, the pair of second slot  218  is formed to be penetrated to the side of the housing forming a curved surface, respectively, and viewed from longitudinal one side or other side of the joint housing  210 , it is arranged to face each other at a position different from the first slot  216 . 
     That is, viewed from longitudinal one side or other side of the joint housing  210 , the pair of first slot  216  and second slot  218  are arranged to form a cross shape. 
     The pair of first slot  216  arranged to face each other is inserted with the first coupling shaft  225  arranged to in a row to the first shaft coupling portion  220  such that the straight line direction movement and the rotation to the longitudinal direction of each joint housing  210  are possible. Further, the pair of second slot  218  arranged to face each other is inserted with the pair of the second coupling shaft  235  arranged in a row to the second shaft coupling portion  230  such that the straight line direction movement and the rotation to the longitudinal direction of the joint housing  210  are possible, respectively. 
     By the fitting coupling made between the pair of the first slot  216  and the first coupling shaft  225 , the straight line direction movement and the rotation of the first shaft coupling portion  220  are possible to the joint housing  210 . In addition, by the fitting coupling between the pair of the second slot  218  and the second coupling shaft  235 , the straight line movement and the rotation of the second shaft coupling portion  230  can be coupled to the joint housing  210 . 
     The first shaft coupling portion  220  is inserted to the inner space of the joint housing  210  through the insertion portion. Such first shaft coupling portion  220  is connected to any one of the valve shaft  330  and the knob shaft  116 , and it includes the first coupling shaft  225  and the first shaft coupling pipe  227 . In the present implementation, the first shaft coupling portion  220  is exemplified as being connected with the valve shaft  330 . 
     The first shaft coupling portion  220  is inserted into the inner space of the joint housing  210  and coupled to the joint housing  210  by the pair of first coupling shaft  225  arranged in a row, and thus, it can be moved and rotated integrally with the first coupling shaft  225 . 
     The first shaft coupling pipe  227  is formed to be extended to the longitudinal direction of the joint housing  210  and protruded outside the joint housing  210 , and can be moved and rotated integrally with the first shaft coupling portion  220 . The first shaft coupling pipe  227  is the part provided for connecting between the first shaft coupling portion  220  and the valve shaft  330 , and the knob shaft  116  is coupled to the first shaft coupling pipe  227 , and thus, the connection between the first shaft coupling pipe  220  and the valve shaft  330  is made. 
     The first shaft coupling pipe  227  is protruded to the outside the joint housing  210  via the longitudinal other side of the joint housing  210  and coupled with the valve shaft  330  from the outside the joint housing  210  and can be protruded to the outside the joint housing  210  by passing through the side plate portion  214  via the secured passage by the through hole  214   a  formed to be penetrated inside the side plate portion  214 . 
     According to the present implementation, the rotation of the first shaft coupling portion  220  is made about the first coupling shaft  225  by the rotation of the first coupling shaft  225 , a direction to which the end of the first shaft coupling pipe  227  faces can be changed as an angle by which the first shaft coupling portion  220  is rotated. Hereinafter, the direction to which the end of the first shaft coupling pipe  227  faces will be expressed as a position of the first shaft coupling portion  220  is changed. 
     The second shaft coupling portion  230  is inserted into the inner space of the joint housing  210  through the insertion portion and arranged between the insertion portion and the first shaft coupling portion  220 . The second shaft coupling portion  230  is connected to other one of the valve shaft  330  and the knob shaft  116  and may include a second coupling shaft  235  and a second shaft coupling pipe  237 . In the present implementation, the second shaft coupling portion  230  is illustrated as being connected to the knob shaft  116 . 
     The second shaft coupling portion  230  is inserted into the inner space of the joint housing  210  and is coupled to the joint housing  210  by a pair of second coupling shafts  235  arranged in a row, and can be moved and rotated integrally with the second coupling shaft  235 . 
     The second shaft coupling pipe  237  is formed to extend in the longitudinal direction of the joint housing  210  and is protruded to the outside the joint housing  210 , and can be moved and rotated integrally with the second shaft coupling portion  230 . The second shaft coupling pipe  237  is the portion provided for the connection between the second shaft coupling portion  230  and the knob shaft  116 . The knob shaft  116  is coupled to the second shaft coupling pipe  237 , and thus, the connection between second shaft coupling portion  230  and the knob shaft  116  can be made. 
     The second shaft coupling pipe  237  protrudes to the outside of the joint housing  210  through longitudinal one side of the joint housing  210  and is coupled to the knob shaft  116  from the outside the joint housing  210 , and may be protruded to the outside the joint housing  210  through the secured passage by the insertion portion. 
     According to the present implementation, when the rotation of the second shaft coupling portion  230  is made about the second coupling shaft  235  by the rotation of the second coupling shaft  235 , the direction to which the end of the second shaft coupling pipe  237  faces may be changed by the angle at which the second shaft coupling portion  230  is rotated. Hereinafter, the direction to which the end of the second shaft coupling pipe  237  changes will be expressed as a change in the posture of the second shaft coupling portion  230 . 
     The joint spring  260  is inserted into the inner space of the joint housing  210  through the insertion portion and arranged between the first shaft coupling portion  220  and the second shaft coupling portion  230 . The joint spring  260  provides elastic force for recovering the positions of the first shaft coupling portion  220  and the second coupling portion  230  changed by the straight line direction movement of the shaft coupling portion  220 ,  230 , and a posture of the first shaft coupling portion  220  and the second shaft coupling portion  230  changed by the rotation of the shaft coupling pipe  227 ,  237 . 
     In the present implementation, the joint spring  260  is illustrated as including a coil spring formed to have a length extended along the longitudinal direction of the joint housing  210 . Longitudinal one side of the joint spring  260  is coupled to the first shaft coupling portion  220  and the longitudinal other side of the joint spring  260  is coupled to the second shaft coupling portion  230 . The joint spring  260  is provided such that an elastic stretch to the longitudinal direction and the elastic bending deformation to the rotational direction of the first shaft coupling portion  220  or the second shaft coupling portion  230 . 
     The inner surfaces of the first shaft coupling portion  220  and the second shaft coupling portion  230  facing each other, for example, the outer surface of the support boss  224 ,  234  is formed with a fitting groove  222 ,  232  fitting coupled on the longitudinal both sides of the joint spring  260 . 
     Both ends of the joint spring  260  becomes a state received in the fitting groove  222  provided in the first shaft coupling portion  220  and the fitting groove  232  provided in the second shaft coupling portion  230 . In addition, since the supporting boss  224  of the first shaft coupling portion  220  and the support boss  234  of the second shaft coupling portion  230  become an inserted state inside the joint spring  260 , the elastic force is provided to the direction which the spacing between the first shaft coupling portion  220  and the second shaft coupling portion  230  is spaced apart in a state to which the joint spring  260  is stably fixed. 
     In the joint  200 , the first shaft coupling portion  220  is rotatably coupled to the joint housing  210  in any one of the up and down direction and the left and right direction, and the second shaft coupling portion  230  is rotatably coupled to the joint housing  210  in the other one direction of the up and down direction and the left and right direction. 
     That is, the joint  200  of the present implementation can transmit the rotational motion of the knob shaft  116  to the valve shaft  330  while connecting the valve shaft  330  and the knob shaft  116  with one flexible shaft in a form which the first shaft coupling portion  220  is connected to the valve shaft  330  and the second shaft coupling portion  230  is connected to the knob shaft  116 . 
     When the direction to which the valve shaft  330  extends does not coincide or align with the direction to which the knob shaft  16  extends due to the tolerance of the valve shaft  330  generated in the valve assembly  300 , with regard to the joint  200 , as a posture of at least any one of the first shaft coupling portion  220  and the second shaft coupling portion  230  changes, the connecting angle between the first shaft coupling portion  220  and the second shaft coupling portion  230  is changed, thereby absorbing the tolerance of the valve shaft  330  generated in the valve assembly  300 . 
     At this time, in the process of connecting the joint  200  to the valve shaft  330  and the knob shaft  116 , the operator does not have to adjust the connection angle between the first shaft coupling portion  220  and the second shaft coupling portion  230 . When the valve shaft  330  and the knob shaft  116  are connected to both ends of the joint  200  so that the postures of the first shaft coupling portion  220  and the second shaft coupling portion  230  are changed to a state for suitable to connect the valve shaft  330  and the knob shaft  116 . 
     In some examples, since the postures of the first shaft coupling portion  220  and the second shaft coupling portion  230  can be maintained or changed according to the situation by the elastic force provided by the joint spring  260 , separate work for fixing these postures may not be required. 
     In some example, the joint  200  according to the implementation of the present disclosure also serves to transmit a longitudinal motion of the shaft. 
     As shown in  FIG.  39   , in a state which the joint  200  is assembled to the knob assembly, it has the state which the joint spring  260  is compressed. At this time, the support boss  224  of the first shaft coupling portion  220  and the support boss  234  of the second shaft coupling portion  230  are spaced apart from by a predetermined spacing. However, when the stroke in which the knob is pushed is greater than the spacing between the supporting boss  224 ,  234 , the axial motion of the first shaft coupling portion  220  is transmitted to the motion of the second shaft coupling portion  230 , and thus, the valve shaft  330  can be pushed. 
     The structure may result in an effect that the longitudinal error of the shaft can be absorbed at a spacing between the supporting boss  224 ,  234  even when the longitudinal error or the tolerance of the shaft is generated in a manufacturing process of the knob shaft  116  or the valve shaft  330 . 
     The reinforcement cap  250  is coupled to the outside the shaft coupling pipe  227 ,  237  and a reinforcement insert ring  240  is coupled inside the shaft coupling pipes  227 ,  237 . The reinforcement cap  250  and the reinforcement insert ring  240  can be coupled in a fixing method. 
     The knob shaft  116  and the valve shaft  330  inserted into the shaft coupling pipe  227 ,  237  have a D-shaped cross section. The shaft coupling pipe  227 ,  237  is continuously subjected to a torsion torque in a state which the knob shaft  116  and the valve shaft  330  are coupled. The first shaft coupling portion  220  and the second shaft coupling portion  230  may be manufactured by an injection molding method using a synthetic resin material. In this case, the shaft coupling pipe  227 ,  237  is a synthetic resin material. In some examples, it is general that the knob shaft  116  and the valve shaft  330  are the metal material. 
     When the torsion torque is continuously subjected in a state which the knob shaft  116  having a D-shaped cross section and the valve shaft  330  are coupled inside the shaft coupling pipe  227 ,  237  which is the synthetic resin material, the shaft coupling pipe  227 ,  237  can be damaged. 
     In order to secure the durability of the shaft coupling pipe  227 ,  237 , it has the structure that the reinforcement cap  250  of metal material surrounds the outer circumferential surface of the shaft coupling pipe  227 ,  237 , and the reinforcement insert ring  240  surrounds the inner circumferential surface of the shaft coupling pipe  227 ,  237 . 
     Such structure reinforces the strength of the shaft coupling pipe  227 ,  237 , thereby improving the durability of the joint  200 . 
     In some examples, the reinforcement insert ring  240  is provided with a slit  242 . The slit  242  serves to secure the flexibility such that it can be restored to the original shape after the cross section of the reinforcement insert ring  240  is changed by corresponding to the rotating valve shaft  330  or the knob shaft  116 , even when the valve shaft  330  or the knob shaft  116  having the D-shaped cross section is rotated inside the reinforcement insert ring  240  having the D-shaped cross section. 
     In addition, inside the shaft coupling pipe  227 ,  237  is provided with a blocking protrusion  221 ,  231  for limiting the coupling depth of the knob shaft  116  or the valve shaft  330 . The knob shaft  116  and the valve shaft  330  contact with the blocking protrusions  221 ,  231  so that it cannot be inserted beyond the above, thereby adjusting the coupling depth between the knob shaft  116  and the valve shaft  330 . The blocking protrusion  221 ,  231  serves to transmit the axial motion of the knob shaft  116  to the first shaft coupling portion  220  and transmit the axial motion of the second shaft coupling portion  230  to the valve shaft  330 . 
     The joint  200  having the above-described configuration can be assembled in the following manner. 
     Firstly, the first shaft coupling portion  220  is tilted and inserted inside the joint housing  210  through the insertion hole and then the first coupling shaft  225  is fitted into the first slot  216  to make the assembly of the joint housing  210  and the first shaft coupling portion  220 . At this time, when the rotation direction of the first shaft coupling portion  220  is left and right direction, the direction of tilting the first shaft coupling portion  220  in order to insert the first shaft coupling portion  220  inside the joint housing  210  is up and down direction. 
     Then, after inserting the joint spring  260  inside the joint housing  210  through the insertion portion, the second shaft coupling portion  230  is inserted by tilting, and then the second coupling shaft  235  is fitted into the second slot  218 , so as to form an assembly between the joint housing  210  and the second shaft coupling portion  230 . At this time, when the rotation direction of the second shaft coupling portion  230  is the up and down directions, in order to insert the second shaft coupling portion  230  inside the joint housing  210 , the direction of tilting the second shaft coupling portion  230  is the left and right directions. 
     In this process, the joint springs  260  can be stably coupled to the first shaft coupling portion  220  and the second shaft coupling portion  230  in a state that the longitudinal both sides thereof are fitted into the fitting groove  222  and the longitudinal both sides of the movement are constrained. 
     As described above, the assembly of the joint  200  according to the present implementation is made by fitting the first shaft coupling portion  220  to the joint housing  210  and assembling it, and inserting the joint spring  260  to the joint housing  210 , and subsequently, fitting the second shaft coupling portion  230  to the housing and assembling it. 
     For example, the assembly of the joint  200  can be easily and quickly made only by a sequential fitting operation without using separate fastening structure or an adhesive. In this example, since the joint  200  includes only four parts, the manufacturing and the management of the part is easy and the assembly of the joint  200  can be made more easily and quickly. 
     In some implementations, when the assembly of the joint  200  is completed, the fitting coupling state of the first shaft coupling portion  220  and the second shaft coupling portion  230  is stably maintained by the elastic force provided by the joint spring  260 , and thus, the assembly of the joint  200  is not optionally released during use of the joint  200 . 
     The joint  200  serves to absorb the position error of the valve shaft  330  between the knob shaft  116  and the valve shaft  330  and provides the structure that the rotation of the first shaft coupling portion  220  and the second shaft coupling portion  230  is possible in order to absorb the position error of the valve shaft  330 . However, it needs a structure for limiting the rotation range of the first shaft coupling portion  220  and the second shaft coupling portion  230 , that is, the posture change range of the first shaft coupling portion  220  and the second shaft coupling portion  230  within the necessary range, according to the property of the product which the joint  200  is installed. 
     The posture change range of the first shaft coupling portion  220  is determined by the size of the through hole  214   a . For example, the first shaft coupling portion  220  can be rotated only within a range in which interference between the inner circumferential surface of the first shaft coupling pipe  227  and the side plate portion  214  is not generated, and the further rotation of the first shaft coupling portion  220  is limited from the point in which the interference between the inner circumferential surface of the first shaft coupling pipe  227  and the side plate portion  214  is generated. Therefore, the posture change range of the first shaft coupling portion  220  is determined by the size of the through hole  214   a  whose the first shaft coupling portion  22   y  determines the size of the passage for passing through the side plate portion  214 . 
     In other words, the rotation of the first shaft coupling portion  220 , that is, the posture change of the first shaft coupling portion  220  is limited to the range between the point which the interference between the inner circumferential surface of the side plate portion  214  and the first shaft coupling pipe  227  at the time of one direction rotation of the first shaft coupling portion  220  and the point which the interference between the inner circumferential surface of the side plate portion  214  and the first shaft coupling pipe  227  is made at the time of the other side rotation of the first shaft coupling portion  220 . 
     According to the present implementation, the size of the through hole  214   a  is determined such that the inner diameter of the side plate portion  214  formed with the through hole  214   a  is larger than the outer diameter of the first shaft coupling pipe  227  and is smaller than the inner diameter of the joint housing  210 . At this time, the size of the through hole  214   a  can be suitably adjusted depending on the posture change range of the first shaft coupling portion  220  to be established. That is, by increasing the size of the through hole  214   a  close to the inner diameter of the joint housing  210 , the posture change range of the first shaft coupling portion  220  can be enlarged, and by reducing the size of the through hole  214   a  close to the outer diameter of the first shaft coupling pipe  227 , the posture change range of the first shaft coupling portion  220  can be reduced. 
     The second coupling shaft  235  provided in the second shaft coupling portion  230  may include a stopper  235   a.    
     The stopper  235   a  is formed so as to be protruded outside the second coupling shaft  235  and the position inside the second slot  218  in accordance with the rotation of the second coupling shaft  235  is changed. The stopper  235   a  is arranged inside the second slot  218  such that the interference with the inner wall of the joint housing  210  formed by the second slot  218  at a set position is made. 
     According to the present implementation, the second slot  218  is formed with a width corresponding to the outer diameter of the second coupling shaft  235  (the outer diameter except the stopper). That is, the second slot  218  is formed so that the width of the second slot  218  and the outer diameter of the second coupling shaft  235  are identical, the coupling between the second shaft coupling portion  230  and the joint housing  210  can be made without generating a rattling when the second shaft coupling portion  230  moves and rotates on the joint housing  210  and it can be applied to even the coupling between the first shaft coupling portion  220  and the joint housing  210 . 
     In addition, the stopper  235   a  is formed so as to be protruded toward the inside of the second slot  218  and is formed to be protruded with narrower width than the width of the second slot  218 . Thus formed stopper  235   a  is rotated together with the second coupling shaft  235  when the rotation of the second coupling shaft  235  is made, and when the rotation of the second coupling shaft  235  is made by the predetermined angle or more, it is interfered with the inner wall of the joint housing  210  formed by the second slot  218 , thereby limiting further rotation of the second coupling shaft  235 . 
     In other words, the rotation of the second shaft coupling portion  230 , that is, the posture change of the second shaft coupling portion  230  is limited to the range between the point which the interference between the inner wall of the joint housing  210  and the stopper  235   a  at the time of one direction rotation of the second shaft coupling portion  230  is made and the point which the interference between the inner wall of the joint housing  210  and the stopper  235   a  is made at the time of the other direction rotation of the second shaft coupling portion  230 . 
     As another example, instead of providing the stopper  235   a  on the second coupling shaft  235 , the structure for the posture change range limitation of the second shaft coupling portion  230  may be formed in a form identical to the structure for limiting the posture change range of the first shaft coupling portion  220 . 
     That is, a structure for limiting the posture change range of the second shaft coupling portion  230  may be formed in a form of adjusting the posture change range of the second shaft coupling portion  230  by covering the side plate portion  214  on longitudinal one side portion of the joint housing  210  and adjusting the size of the through hole  214   a  formed in the inner side of the side plate portion  214 . 
     However, when the structure for limiting the posture change range of the second shaft coupling portion  230  is formed as such form, unlike the side plate portion  214  integrally formed with the joint housing  210  at the longitudinal other portion of the joint housing  210 , the side plate portion at longitudinal one side portion of the joint housing  210  has to be provided in the form of separate cap shaped part form separable from the joint housing  210 . 
     When even the side plate portion of longitudinal one side portion of the joint housing  210  is integrally formed with the joint housing  210 , the passage to be inserted inside the joint housing  210  in order to assembly the parts such as the first shaft coupling portion  220 , the second shaft coupling portion  230 , and the joint spring  260  are blocked. 
     However, as such, when the side plate portion of one side portion in the longitudinal direction of the joint housing  210  is provided in the form of separate cap-shaped part, the number of parts for manufacturing the joint  200  is added to that extent, and as the number of parts is added, the process for manufacturing it is added. Therefore, the part management is much more difficult and the cost and time required for the manufacturing of the joint  200  is increased to that extent. 
     In consideration of this point, instead of adding the part in separate cap shape, by taking the structure of adding the stopper  235   a  for limiting the rotation of the second coupling portion  230  as the protrusion form integrally formed with the second coupling shaft  235 , the joint  200  of the present implementation forms the structure of adjusting the posture change range of the second shaft coupling portion without adding separate part. 
     In some implementations, the joint  200  of the present implementation may be a structure that can be assembled with four parts including the fewer number of parts, for example, the joint housing  210 , the first shaft coupling portion  220 , the second shaft coupling portion  230 , and the joint spring  260 . In this case, the part management and the assembly work may be facilitated, and cost and time required for the manufacturing of the joint  200  may be reduced. 
       FIG.  42    is a perspective view showing a valve assembly of the knob assembly in accordance with an exemplary implementation of the present disclosure, and  FIG.  43    is a perspective view showing a state in which the valve assembly of the knob assembly in accordance with an exemplary implementation of the present disclosure is separated. 
     As shown, the valve assembly  300  includes a valve  310  coupled to the gas pipe frame  35  and the gas pipe  30 , an ignition switch  360  fitted to the valve shaft  330  of the valve  310 , and the knob sensor  400 . 
     The knob sensor  400  includes a knob sensor plate  410  fastened to the valve  310 , a knob sensor housing  430  movably coupled to the knob sensor plate  410  in an axial direction, a sensor spring  420  providing the elastic force between the knob sensor housing  430  and the knob sensor plate  410 , a knob sensor board  440  having the Hall sensor  444  and fastened to the knob sensor housing  430 , and a rotating plate  450  coupled with a knob sensor magnet  460  which is coupled to the valve shaft, rotates integrally with the valve shaft, and sensed by the Hall sensor  444 . 
     The ignition switch  360  has a valve shaft coupling hole  362  having a D-shaped cross section, and is coupled to the valve shaft. Therefore, the ignition switch  360  receives the rotational force of the valve shaft, so that the on/off state of the valve shaft can be switched by the rotational angle. When the valve shaft is rotated by a predetermined angle, the ignition switch  360  becomes on state, it servers to making a spark be generated in the burner. 
       FIG.  44    is a perspective view of showing a valve,  FIG.  45    is an exploded perspective view of a valve,  FIG.  46    is a longitudinal sectional view of a valve of a knob assembly according to the present disclosure, and  FIG.  47    is a transverse cross-sectional view of a valve. 
     As shown, the valve  310  includes a valve body  312 , a valve cap  314 , a main adjustment piece  320 , a valve shaft  330 , a valve spring  340 , and an auxiliary adjustment piece  350 . 
     The main adjustment piece  320  and the auxiliary adjustment piece  350  are arranged inside the valve body  312 . 
     The valve body  312  includes an inflow pipe  312   a  connected to the gas pipe, and a first gas supply pipe connecting portion  312   b  connected to the burner, and a second supply pipe connecting portion  312   c.    
     In addition, inside the valve body  312 , the first flow path  312   d  connecting the outer circumferential surface space of the main adjustment piece  320  and the auxiliary adjustment piece  350 , and the second flow path  312   e  connecting the auxiliary adjustment piece  350  and the second supply pipe connecting portion  312   c.    
     The main adjustment piece  320  and the auxiliary adjustment piece  350  have the rotation center parallel to the longitudinal direction of the valve shaft and arranged inside the valve body  312 . 
     The main adjustment piece  320  includes a connection hole  325  formed from the rear surface to the front surface, an opening and closing hole  324  penetrating through the inner and outer circumferential surface of the connection hole  325 , and a groove  326  formed along the outer circumferential surface in one side of the opening and closing hole  324 . 
     The auxiliary adjustment piece  350  may include a T-shaped adjustment hole  354  capable of adjusting the amount which gas supplied through the first flow path  312   d  to the second flow path  312   e.    
     The main adjustment piece  320  has a structure for adjusting the gas supply flow rate according to the degree of which the opening and closing hole  324  and the inflow pipe  312   a  are overlapped. Gas introduced through the opening and closing hole  324  is supplied to the first gas supply pipe connection portion  312   b  through the connection hole  325 . 
     At this time, gas supplied through the groove  326  formed on the outer circumferential surface of the main adjustment piece  320  is also supplied through the first flow path  312   d . In gas supplied through the first flow path  312   d , the flow rate supplied to the second supply pipe connecting portion  312   c  is adjusted according to the overlapped degree of an adjustment hole  354  of the auxiliary adjustment piece  350  and the first flow path  312   d.    
     The main adjustment piece  320  is adjusted by the valve shaft  330  and the auxiliary adjustment piece  350  is adjusted by separate tool such as a driver. 
     The auxiliary adjustment piece  350  is for fine adjustment of the amount of gas to be supplied, and may not be adjusted after one adjustment according to the installation environment, and may be adjusted by a service engineers rather than being adjusted by the user. 
     If an access to the auxiliary adjustment piece  350  is not easy, an excessive disassembly operation of the cooking appliance may be needed for the repair engineers to adjust the auxiliary adjustment piece  350 . 
     In the present disclosure, the auxiliary adjustment piece  350  is arranged adjacent to one side of the main adjustment piece  320 , and after separating the knob, the service hole  129  in  FIG.  57    may provide an access to the auxiliary adjustment piece  350 . 
     The main adjustment piece  320  has a key groove  322  into which a key  332  provided on the valve shaft  330  is inserted and a valve spring  340  is arranged between the main adjustment piece  320  and the valve shaft  330 . The valve spring  340  provides the elastic force to a direction which the valve shaft  330  is spaced apart from the main adjustment piece  320 , and provides a structure that the rotation of the valve shaft  330  is transmitted to the main adjustment piece  320  by pressing the valve shaft  330  in a axial direction and inserting the key  332  of the valve shaft  330  to a key groove  322  of the main adjustment piece  320 . 
     The assembly process of the valve  310  is made method by coupling the main adjustment piece  320  and the auxiliary adjustment piece  350  to the valve body  312 , and fastening the valve cap  314  in the valve body  312  in a state that the valve spring  340  and the valve shaft  330  are fitted into the main adjustment piece  320 . The fastening of the valve cap  314  and the valve body  312  may be made by the method of penetrating the fastening hole  314   f  formed in the valve cap  314  and fastening to the fastening hole  314   f  formed in the valve body  312  by using the fastening volt S 6 . 
     The valve cap  314  according to the present disclosure includes a sensor fixed portion  314   d  for fixing the knob sensor  400  described below, and a service hole  314   b  of providing a path in which the tool is accessible with the auxiliary adjustment piece  350 . The service hole  314   b  is provided with the knob assembly provided in the front of the valve  310  and the front panel is provided with the service hole aligned with the service hole  314   b . The sensor fixed portion  314   d  is fastened with the knob sensor plate  410  of the knob sensor  400 . 
       FIG.  48    is an exploded perspective view showing a knob sensor of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  49    is a perspective view showing a state which the knob sensor board of the knob assembly in accordance with an exemplary implementation of the present disclosure is assembled to the knob sensor housing, and  FIGS.  50  and  51    are the cross sectional views for explaining the operation of the valve assembly of the knob assembly of the present disclosure. 
     As shown, the knob sensor  400  includes a sensor plate  410 , a sensor spring  420 , a knob sensor housing  430 , a knob sensor board  440 , and a rotating plate  450 . 
     The sensor plate  410  provides a fastening hole  432  to be fastened to the valve cap  314  described above. The sensor plate  410  is fixed to the valve cap  314  and serves to fix the position of the sensor housing  430  and to support the sensor spring  420  that provides the elastic force to the sensor housing  430 . 
     The fastening hole  432  of the sensor plate  410  is fastened to the fastening hole  314   d  of the valve cap ( 314  in  FIG.  44   ) using a fastening bolt S 7 . 
     The sensor plate  410  provides a valve shaft hole  412  at a central portion. Since the sensor plate  410  should not be affected by the pressing or rotation of the valve shaft  330 , the valve shaft through hole  412  has an inner diameter larger than the outer diameter of the valve shaft  330 . 
     A spring fixed portion  415  in which the sensor spring  420  is seated to the outside of the valve shaft through hole  412  is provided. The rear end side of the sensor spring  420  is inserted into the spring fixed portion  415  and the portion is fixed. The sensor spring  420  provides an elastic force in a direction in which the knob sensor housing  430  positioned in front of the sensor plate  410  is spaced apart from the sensor plate  410 . It is such that the knob sensor board  440  mounted on the knob sensor housing  430  and the rotating plate  450  arranged in front of the knob sensor board  440  to maintain the predetermined spacing. 
     Since the sensor plate  410  has a structure in which the elastic force of the sensor spring  420  is repeatedly applied, three or more points are fastened to the valve cap  314  for stable fastening, for instance. In some examples, the sensor plate  410  may maintain a fixed state correctly in a predetermined posture. 
     In some implementations, the sensor plate  410  provides a plurality of guide protrusions  411  protruded forward. The guide protrusion  411  is inserted into a guide portion  431  provided in the knob sensor housing  430  so that the knob sensor housing  430  can maintain a predetermined posture. 
     In some examples, three or more guide protrusions  411  are arranged at the circumference of the valve shaft through hole  412 . The knob sensor housing  430  can move forward and rearward to the longitudinal direction of the valve shaft  330  while maintaining the state parallel to the sensor plate  410  by the guide protrusion  411 . 
     The knob sensor housing  430  serves to fix the knob sensor board  440  and to maintain the rotating plate  450  and the knob sensor board  440  at a predetermined spacing. 
     The knob sensor  400  is operated in a principle of sensing the rotational angle of the valve shaft  330  by sensing the position of the knob sensor magnet  460  provided in the rotating plate  450  via the plurality of Hall sensors  444  arranged radially to the knob sensor board  440 . 
     Referring to  FIG.  49   , seven Hall sensors  444  are arranged on the knob sensor board  440  so as to have a radially equal spacing. The rightmost Hall sensor below the rightmost is referred to as the first, and others are referred to as the second to the seventh Hall sensor. 
     The knob sensor  400  constitutes an absolute coordinate in such a manner that a signal of a different kind is generated for each Hall sensor  444  and the position of the knob sensor magnet  460  is sensed by using the absolute coordinate configured as such. 
     For example, regardless of the position immediately before the knob sensor magnet  460 , if a finally received signal is a signal generated by the n th  Hall sensor, the position of the knob sensor magnet  460  is sensed as a position corresponding to the n th  Hall sensor area. 
     Therefore, even when the operation of the knob is rapidly made, finally, the final position of the knob sensor magnet  460  can be precisely sensed in a state when the rotation of the knob handle is completed, thereby accurately grasping the fire power thus set. 
     When the knob sensor  400  has a method of using a relative coordinate which is a method that senses a position change from a position immediately before the knob sensor magnet  460 , when the knob is rotated at a very high speed, a problem may be generated that the position sensing of the knob sensor magnet  460  may not be made properly. 
     For example, in order for the position of the knob sensor magnet  460  moved from the position corresponding to the first Hall sensor area to the position corresponding to the seventh Hall sensor area to be accurately recognized, on state change in the second to the seventh Hall sensors has to be made sequentially. When the movement of the knob sensor magnet  460  is made at a rapid speed, on status change in some Hall sensor cannot be made, and in this case, the error can be generated in the positioning of the knob sensor magnet  460 . In this case, the error of recognizing the position of the knob sensor magnet  460  as the position corresponding to the area between the second Hall sensor and the sixth Hall sensor, or recognizing that the rotation of the knob is not made. 
     In some examples, the rotating plate  450  may be fixed to rotate together with the valve shaft  330 . In other examples, the knob sensor board  440  may maintain a predetermined posture regardless of the rotation of the valve shaft  330 . 
     In some examples, the valve shaft  330  not only rotates but also moves forward and backward even in the axial direction. The rotating plate  450  fixed to the valve shaft  330  moves along with the movement of the valve shaft  330 . Hereinafter, the direction in which the valve shaft  330  is moved to the inner side of the cooking appliance by pushing the knob is referred to as backward, and the opposite direction is referred to as forward. 
     When the rotating plate  450  is moved backward, the knob sensor housing  430  positioned at the rear of the rotating plate  450  is pushed by the rotating plate  450  and moved to the inside the cooking appliance. 
     When the valve shaft  330  moves forward due to the restoring force of the valve spring, the rotating plate  450  also moves forward. At this time, since the knob sensor housing  430  is not affected by the movement of the valve shaft  330 , it moves forward with the rotating plate  450  by the restoring force of the sensor spring  420  provided between the knob sensor housing  430  and the knob sensor plate  410 . 
     Therefore, the knob sensor housing  430  is also moved forward and backward in response to the forward and backward movement of the rotating plate  450 , so that the spacing between the rotating plate  450  and the knob sensor housing  430  is maintained constant. As a result, the spacing between the knob sensor magnet  460  provided on the rotating plate  450  and the Hall sensor  444  provided on the knob sensor board  440  fastened to the knob sensor housing  430  can be maintained constant. 
     In some examples, the spacing between the knob sensor board  440  and the rotating plate  450  may be set by a plurality of support protrusion  435  provided on the knob sensor housing  430 . In some examples, three support protrusions  435  may be arranged with a spacing of 120°. Since three points can define a plane, when forming three support protrusions, the support protrusion  435  may contact the rotating plate  450  to maintain a constant spacing between the rotating plate  450  and the knob sensor housing  430 . 
     The center of the knob sensor board  440  is provided with a valve shaft through hole  442  through which the valve shaft  330  is penetrated, and the periphery thereof is provided with the support protrusion through hole  445  through which the support protrusion  435  provided on the knob sensor housing  430  is penetrated. 
     The knob sensor board  440  may be coupled to the knob sensor housing  430  through a fastening bolt S 8  and a fastening protrusion  434 . In the case of the illustrated implementation, the knob sensor board  440  is provided with four fastening holes  443  and the knob sensor housing  430  is provided with two fastening holes  433  and two fastening protrusions  434 , and it is the structure which two points are fastened to the fastening bolt S 8  and other two points are fixed to the fastening protrusion  434 , but the number of the fastening of the fastening bolt S 8  can be increased and decreased. 
     Referring to  FIGS.  50  and  51   , when the knob is pushed, the joint  200  is moved to the right in the figure, the sensor spring  420  and the valve spring  340  are compressed by the movement of the joint  200 , and the valve shaft  330  and the knob sensor housing  430  in which the rotating plate  50  and the knob sensor board  440  are fastened together, and are moved together to the right. 
     When the pushing force is removed, by the restoring force of the valve spring  340  and the sensor spring  420 , the valve shaft  330 , the knob sensor housing  430  to which the knob sensor board  440  is fastened, and the rotating plate  450  are restored to the original position. 
     The knob sensor plate  410  is fastened to the valve cap  314  and the sensor spring  420  provides elastic force in a direction to closely attach the knob sensor housing  430  to the rotating plate  450 . Therefore, the rotating plate  450  contacts with the first shaft coupling pipe  227  of the joint  200 , and in the knob sensor housing  430 , the support protrusion  435  contacts with the rotating plate  450 . 
     A state which the supporting protrusion  435  of the knob sensor housing  430  contacts with the rotating plate  450  is always maintained in a state before the knob is pushed such as  FIG.  50   , or in a state when the knob is pushed as show in  FIG.  51   . 
     Therefore, in spite of the axial movement of the valve shaft, the knob sensor plate  410  and the rotating plate  450  of the knob sensor can always maintain the predetermined spacing, and thus, the spacing between the knob sensor magnet  460  arranged to the rotating plate  450  and the Hall sensor  444  arranged at the knob sensor plate  410  can be maintained constantly. Such structure improves the operation reliability of the knob sensor  400 . 
       FIG.  52    is a longitudinal sectional view for explaining the operation and supporting structure of the knob of the knob assembly in accordance with an exemplary implementation of the present disclosure. 
     First, the support structure of the knob  110  will be reviewed. The knob  110  has the structure which penetrates through the inner support pipe  124   f  and the outer supporting pipe  124   c  of the knob ring  120 , and penetrates through the fixed pipe  190 , and fitting coupled to the first shaft coupling portion of the joint  200 . 
     The knob shaft  116  is supported at the first support point P 1  on the inner surface of the inner supporting pipe and may be supported at the second supporting point P 2  inside the fixed pipe  190 . The rotational force of the knob shaft  116  is transmitted to the second shaft coupling portion  230  of the joint  200  to which the end is fastened, and the knob ring  120  and the fixed pipe  190  merely perform the function of supporting the knob shaft  116 , and the rotational force of the knob shaft  116  is not received. 
     In some examples, in order to improve the assembly convenience of the knob shaft  116 , the knob shaft  116  includes a large diameter portion  116   a  starting from a portion to which the knob ring body is coupled, a small diameter portion  116   c  starting from an end coupled to the joint, and a tapered portion  116   b  whose outer diameter is reduced therebetween. 
     A portion of the large diameter portion  116   a  and the first tube part  192  are received in the outer supporting pipe  124   c  of the knob ring  120 . 
     The outer supporting pipe  124   c  of the knob ring back plate  124  is formed to have an inner diameter corresponding to the large diameter portion  116   a  and the inner supporting pipe  124   f  of the knob ring back plate  124  is formed with the first portion  124   f _ 1  having the inner diameter corresponding to the large diameter portion  116   a  and the second portion  124   f _ 2  having the inner diameter corresponding to the small diameter section. Such structure results in an effect of capable of smoothly inserting the knob shaft  116  to the outer supporting pipe  124   f.    
     In addition, a first supporting point P 1  is formed on the inner circumferential surface of the second portion  124   f _ 2 . 
     In some implementations, it provides the structure that the small diameter portion  116   c  of the knob shaft  116  protruded to the inner supporting pipe  124   f  is again supported at the second supporting point P 2  inside the fixed pipe  190  and two points are supported as a whole. The fixed pipe  190  includes a fixed circular plate portion  191  fastened to the fixed frame, the first tube part  192  extending from the fixing circular plate portion and having a shape which the inner diameter is reduced, and the second tube part surrounding the second shaft coupling pipe  237  of the joint  200 . In some examples, the second tube part  193  has an incision portion  193   a  formed in the longitudinal direction of the shaft so that the second shaft coupling pipe  237  can be easily coupled to the second tube part  193 . 
     The knob shaft  116  has the structure fitting coupled to the second shaft coupling pipe  237  of the joint  200  inside the second tube part  193  of the fixed pipe  190 , after penetrating through the outer supporting pipe  124   c  and the inner supporting pipe  124   f  of the knob ring back plate  124 , and at this time, the supporting of the knob shaft  116  are made at a first supporting point P 1  arranged inside the inner supporting pipe  124   f  and the second point P 2  arranged inside the fixed pipe  190 . 
       FIG.  53    is a rear view showing a knob ring of the knob assembly in accordance with an exemplary implementation of the present disclosure,  FIG.  54    is a transverse cross-sectional view showing the coupling state of the knob ring of the knob assembly in accordance with an exemplary implementation of the present disclosure, and  FIGS.  55  and  56    are the views for explaining the operation of the knob ring of the knob assembly in accordance with an exemplary implementation of the present disclosure. 
     The knob  110  and the knob ring  120  are coupled to the front surface of the front panel  10  and the support frame  150  and the actuating member  170  and the fixed frame  180  are coupled to the rear surface of the front panel  10 . 
     The support frame  150  is fastened to the rear surface of the front panel  10  and the actuating member  170  penetrates through the front panel  10  and is fastened to the knob ring  120 . At this time, the rotation center of the actuating member  170  is arranged to coincide with the rotation center of the knob  110 . The actuating member  170  serves to constrain the rotation center of the knob  110  to be at a center position with regard to the front panel  10 . For example, when the actuating member  170  is fixed in the center position about the front panel  10 , the knob  110  can be fixed in the correct position with regard to the front panel  10 . 
     The actuating member  170  is inserted inside the support frame  150  and some are protruded to the front surface of the front panel  10  through the front panel  10 . The front of the actuating member  170  is protruded to the front surface of the front panel which the operating portion  171  having the cylindrical shape is formed and the operating portion  171  is formed longer than the thickness of the support frame  150 . 
     The inner circular plate area  124   j  of the knob ring back plate  124  is coupled with the operating portion  171  of the actuating member  170  protruded to the front surface of the front panel  10 . The knob ring  120  is coupled to the actuating member  170  supported by the support frame  150 , and, consequently, the supporting structure in which the knob ring  120  is supported by the support frame  150  is formed. 
     The operation of the knob ring  120  can be recognized by the rotation of the actuating member  170  rotated connected with the rotation of the knob ring  120 . Since the knob ring  120  is the part exposed to the outside the front panel  10 , a knob ring sensor  500  for sensing the operation of the knob ring  120  being installed around the knob ring  120  from the outside of the front panel  10  is externally not good. 
     In view of the above, in the present implementation, the knob ring sensor  500  is installed around the actuating member  170  inside the front panel  10 , and the knob ring sensor  500  installed as such can sense the rotation of the knob ring  120  in a manner of sensing the rotation of the actuating member  170  inside the front panel  10 . 
     In some examples, the knob assembly structure of the present implementation is provided with a fixed frame  180  for preventing the actuating member  170  from being deviate to the rear surface so that the actuating member  170  can stably operate. 
     The fixed frame  180  is provided as the form across the rear surface of the actuating member  170  and is fixed to the support frame  150 . The fixed frame  180  makes the actuating member  170  not be deviated to the rear surface while limiting the rotation range of the actuating member  170  within the designated range. And the extended portion  173  of the actuating member  170  can be moved only within the pivotable region  182  of the fixed frame  180 . 
     According to the present implementation, the actuating member  170  has an extended portion  173  formed to be extended outwardly the circular plate portion  172  formed on the rear surface, and the extended portion  173  is formed inside the fixed frame  180 . 
     As such, the extended portion  173  arranged inside the fixed frame  180  can move within a movable region within the fixed frame  180 , and, from the point interfered with the upper side inner wall and the lower side inner wall of the fixed frame  180 , the movement thereof is limited. 
     As such, when the movement range of the extended portion  173  is limited by the fixed frame  180 , the rotation angle in both directions of the actuating member  170  can be limited within the predetermined range. 
     By applying the structure in which the extended portion  173  is provided on both sides of the actuating member  170  and the movement range limitation of each extended portion  173  is made at the same position, the rotational range limit of the actuating member  170  can be made more stably. 
     In addition, the actuating member  170  is coupled to a pair of restoring springs  156   a ,  156   b  that provide an elastic force to return the actuating member  170  to the initial position, which is rotated from its initial position to spaced position. 
     The actuating member  170  and the knob ring  120  are integrally rotated so that the knob ring  120  maintains the initial position due to the elastic force of the restoring spring  156  connected to the actuating member  170 . Further, the knob ring  120  maintaining the initial position as the above can rotate clockwise or counterclockwise at a predetermined angle. When the external force is released in the rotated state, it can be returned to the initial position by the restoring force which the restoring spring  156   a ,  156   b  provides. 
     For example, when the actuating member  170  is rotated in the counterclockwise by the operation of the knob ring  120 , as shown in  FIG.  54   , the first restoring spring  156   a  of the pair of restoring springs provides the elastic force working clockwise so that the actuating member  170  can be returned to its initial position. Further, the second restoring spring  156   b , which is the other one of the pair of restoring springs  156  provides the elastic force working counterclockwise such that the actuating member  170  is returned to the initial position, when the actuating member  170  is rotated clockwise by the operation of the knob ring  120 , as shown in  FIG.  10   . 
     In some examples, referring to  FIG.  54   , the restoring magnet  158 ,  178  is provided at the corresponding portion to each other of the support frame  150  and the circular plate portion  172  of the actuating member  170 , respectively. The restoring magnet  158  is arranged such that the restoring magnet  178  provided in the actuating member  170  and the restoring magnet  158  provided in the support frame  150  are aligned when the actuating member  170  is in the origin. The restoring magnet  158 ,  178  is arranged such that a different polarity from each other is arranged in order to work an attraction mutually. 
     The restoring magnet  158  provided in the support frame  150  is fitted coupled from the left side to the right side in the drawing and is fitted and coupled from the right side to the left side in the drawing of the restoring magnet  178  provided on the actuating member  170 . This is for the attraction working between the restoring magnets  158 ,  178  to work in the direction in which the restoring magnet  158 ,  178  is inserted into the groove. Such structure results in an effect of preventing the restoring magnet  158 ,  178 , which is tilted by fitting the restoring magnet  158 ,  178 , from deviating without using separate adhesive. 
     The knob ring sensor magnet  530  is provided to change the position by being connected with the rotation of the actuating member  170  and the knob ring sensor  500  senses a position change of the knob ring sensor magnet  530 , thereby sensing the rotation of the knob ring  120 , and, senses the rotation of the knob ring  120  connected to the actuating member  170 . 
     The knob ring sensor magnet  530  is the configuration which is the sensing subject of the knob ring sensor  500  and installed on the actuating member  170 . In the present implementation, it is exemplified as for the knob ring sensor magnet  530  to be installed at the circular plate portion  172  of the actuating member  170 . In  FIGS.  55 ,  56   , the knob ring sensor magnet  530  is covered at the rear side of the knob ring sensor board  520 , and the knob ring sensor magnet  530  is shown in a dotted line in the above Figures. 
     The knob ring sensor magnet  530  is installed on the circular plate portion  172  and installed so as to be arranged on one side of the circular plate portion  172  facing the knob ring sensor  500 . The position of the knob ring sensor magnet  530  installed as such can be changed in a form that it is rotated together with the actuating member  170  when rotating the actuating member  170 . 
     In the present implementation, it is exemplified that the knob ring sensor magnet  530  is arranged at a position adjacent to the outer circumferential surface of the circular plate portion  172 . The position of the knob ring sensor magnet  530  arranged at such a position can be changed by drawing a trajectory similar to the shape of the outer circumferential surface of the circular plate portion  172  which is circular shape when rotating the actuating member  170 . 
     The knob ring sensor  500  is provided to sense a position change of the knob ring sensor magnet  530  and is fastened to the support frame  150  at the rear surface of the actuating member  170 . 
     As an example, the knob ring sensor  500  may include a knob ring sensor housing  510 , a knob ring sensor board  520 , and Hall sensor  522   a ,  522   b.    
     The knob ring sensor housing  510  is installed to be fixed to the support frame  150  or, for example, to the lower side of the frame main body portion  141 . The knob ring sensor housing  510  is installed with the knob ring sensor board  520  connected to the controller of the cooking appliance. 
     In the present implementation, the knob ring sensor board  520  is installed on the knob ring sensor housing  510  and is illustrated as being installed on the side facing the frame main body portion  141  and the knob ring sensor magnet  530 . Further, a sensor for sensing the position change of the knob ring sensor magnet  530  is installed on the knob ring sensor board  520 . 
     The knob ring sensor  500  having the above-described configuration senses the position of the knob ring sensor magnet  530  in a non-contact manner, like the knob sensor  400 . For this, the knob ring sensor magnet  530  includes a magnetic member of generating a magnetic force, and the knob ring sensor  500  includes a Hall sensor  522  of sensing the magnetic force of the magnetic member adjacent with a predetermined distance. The Hall sensor  522  is installed on the knob ring sensor board  520 . When the knob ring sensor magnet  530  approaches the Hall sensor  522  within a predetermined distance, it senses the magnetic force of the knob ring sensor magnet  530 , and generates a signal corresponding thereto. 
     The knob ring sensor  500  includes a plurality of Hall sensors  522  and the plurality of Hall sensors  522  are arranged to be spaced apart at a predetermined spacing along the rotation path of the knob ring sensor magnet  530 . 
     That is, when rotating the actuating member  170 , when the knob ring sensor magnet  530  is rotated in the circular trajectory similar to the shape of the outer circumferential surface of the circular plate portion  172 , the knob ring sensor  500  is arranged in a form which the plurality of Hall sensors  522  are positioned on the arc corresponding to the rotation trajectory of the knob ring sensor magnet  530 . 
     In the present implementation, it is exemplified that a pair of Hall sensors  522   a  and  522   b  are arranged on the knob ring sensor  500 , and the arrangement of the Hall sensor  522   a ,  522   b  and the knob ring sensor magnet  530  is made in a form positioning between the pair of the Hall sensors  522  when the knob ring  120  and the actuating member  170  are in the initial position. 
     According to it, at the time of one direction rotation of the knob ring  120 , the knob ring sensor magnet  530  approaches to any one (hereinafter referred to as “left side Hall sensor”) of the pair of Hall sensors  522 , and the sensing about the knob ring sensor magnet  530  in the corresponding Hall sensor  522   a  is made, and at the time of the other direction of the knob ring  120 , the knob ring sensor magnet  530  approaches to the other one (hereinafter referred to as “the right side Hall sensor”) of the pair of Hall sensors  522 , and the sensing about the knob ring sensor magnet  530  in the corresponding Hall sensor  522   b  is made. 
     When the knob ring  120  is provided to provide a timer function, and the knob ring  120  is rotated in one direction, the knob ring sensor magnet  530  approaches within the predetermined distance to the left Hall sensor  522   a , the sensing with regard to the knob ring sensor magnet  530  in the left Hall sensor  522   a  is made, and accordingly, the operation of the knob ring  120  for the time operation initiation is sensed by the knob ring sensor  500  such that the operation of the timer can be proceeded. 
     In addition, the knob ring is rotated to the other direction, the knob ring sensor magnet  530  approaches within the predetermined distance to the right Hall sensor  522   b  and the sensing with regard to the knob ring sensor magnet  530  in the right Hall sensor  522   b  is made, and accordingly, the operation of the knob ring  120  for the time operation initiation is sensed such that the operation of the timer can be proceeded. 
     In the present implementation, it is exemplified as generating a different kind of signal for each Hall sensor  522 . That is, the signal generated by the left Hall sensor  522   a  is different from the signal generated by the right Hall sensor  522   b.    
     By using this, the function of the knob ring  120  may be configured such that the set time of the timer is set differently according to the rotation direction of the knob ring  120  and the function of the knob ring  120  may be configured such that each different function is provided according to the rotation direction of the knob ring  120 . 
     As an example, the function of the knob ring  120  may be configured such that the set time of the timer is set in a 10 minutes unit at the time of one direction rotation, and the set time of the timer is set in 1 minute unit at the time of the other direction rotation. 
     In addition, when maintaining the state rotated in one direction for a predetermined time or more, the set time can be continuously increased. For example, when the knob ring  120  is rotated to the right, the timer set time is increased by 10 minutes unit, and the knob ring  120  is rotated to the left and then immediately returned (hereinafter, referred to as a click), in the case of increasing by the timer set time by 1 minute unit, when the state rotated to the right is maintained for a predetermined time (for example, 3 seconds) or more (hereinafter referred to as long pushing), the timer set time is continuously increased in 10 minutes unit. 
     In other words, the timer set time of one unit can be increased by a short click, and the continuous increase of the timer set time can be made through a long push. 
     Since this click and long push all can be applied to the left and right direction of both sides, four signals can be set using two Hall sensors. 
     In some cases, two of four signals may be used as a signal for the timer time setting, and the remaining two signals may be used as a signal for setting other function such as selecting a cooking mode. 
     As another example, the function of the knob ring  120  may be configured such that a timer is set at the time of one way rotation of the knob ring  120  and the release of the timer set is released at the time of the other direction rotation of the knob ring  120 . 
     As still another example, the function of the knob ring  120  may be configured such that the timer function is provided at the time of one direction rotation of the knob ring  120  and other function is provided other than the timer function at the time of the other direction timer function. 
     In some examples, the signal generated through the Hall sensor  522  may be provided as basic information for grasping information output through the display device  125 . 
     For example, by using a signal generated from the left Hall sensor as basic information, information such as whether to initiate the timer operation, the timer time, etc., can be grasped, and information thus grasped can be displayed in a form of letters, graphics, or colors through the display device  125 . 
       FIG.  57    is a perspective view showing a state in which the knob of the knob assembly in accordance with an exemplary implementation of the present disclosure is separated, and  FIG.  58    is a transverse cross-sectional view in a state which the knob of the knob assembly in accordance with an exemplary implementation of the present disclosure with the knob is separated. 
     The knob assembly according to the present disclosure can be separated by pulling the knob. When the knob is separated, the knob ring back plate  124 , which was covered by the knob, is exposed to the outside. 
     Referring to  FIG.  57   , it can be seen that the locking bracket  140  passes through the bracket hole  124   b  of the knob ring back plate  124  and is fastened to the front panel  10 . At this time, a knob passage groove  144  is formed in the rear of the locking piece  142  of the locking bracket  140 . 
     In a state which the knob is not pushed, the engaging surface ( 114   d  in  FIG.  9   ) of the knob back plate is adjacent to the right side of the locking piece  142  of the locking bracket  140 . When the knob is pushed, the engagement surface ( 144   d  in  FIG.  9   ) is adjacent to the right side of the knob passage groove  144  of the locking bracket  140 . Therefore, the knob can be rotated only when the knob is pushed. 
     A service hole  129  is provided on the left of the knob ring back plate  124 . The service hole  129  is formed in a position aligned with the auxiliary adjustment piece  350  of the valve  310  in a straight line. 
     A tool such as the driver can be entered through the service hole  129  to adjust the auxiliary adjustment piece  350  of the valve  310 . 
     The service hole  129  is formed to penetrate through the knob ring back plate  124 , the front panel  10 , the support frame  150 , and the actuating member  170 , as shown in  FIG.  58   . 
     Such structure results in an effect of improving the convenience of maintenance by separating only the knob without separating the front panel  10  and adjusting the auxiliary adjustment piece  350  of the valve  310 . 
     In some examples, the spacing between the valve shaft  330  and the service hole  129  has to be set in consideration of the size of the joint  200  and the knob sensor  400 . When the radius of the joint  200  is larger than the spacing between the valve shaft  330  and the service hole  129 , the joint interferes on the path of the service hole  129 . 
     Likewise, when the radius of the knob sensor  400  is larger than the spacing between the valve shaft  330  and the service hole  129 , the knob sensor  400  interferes on the path of the service hole  129 . Of course, the service hole  129  may also be penetrated also in the knob sensor  400 . 
     An adjustment of the auxiliary adjustment piece  350  using the service hole  129  may not be generally made, but may be sometimes necessary in the case of manual adjustment by a user. In some cases, the front panel  10  may be disassembled to operate the auxiliary adjustment piece  350 , which may be difficult to be performed by the user and may need to be performed by a service engineer. In some examples, when the knob may be separated, as described in the present disclosure, to operate the auxiliary adjustment piece  350 , a user may perform an adjustment of the auxiliary adjustment piece  350 . 
     While the present disclosure has been described with reference to the implementations shown in the drawings, it will be understood that it is merely illustrative and many variations and equivalent other implementation are possible from the above for those skilled in the art. Therefore, the true technical protection range of the present disclosure should be defined by claims below.