Abstract:
A roaster ( 1 ) and heating cover ( 20 ) thereof are disclosed. The roaster ( 1 ) includes a pot ( 10 ) and a heating cover ( 20 ) covered correspondingly thereon. An inner space of a cover body is separated into an installing chamber ( 2110 ) and a hot air chamber ( 2111 ). A motor ( 22 ) and an actuator ( 24 ) are fixed in the installing chamber ( 2110 ). The hot air supply module ( 23 ) is disposed in the hot air chamber ( 2111 ), and a group of the reduction gears ( 25 ) is driven by the actuator ( 24 ). A stirring component ( 26 ) connecting the group of the reduction gears ( 25 ) is disposed in the hot air chamber ( 2111 ). Thus an inner space of the roaster ( 1 ) will be maintained for flipping the ingredients.

Description:
TECHNICAL FIELD 
       [0001]    The disclosure relates to a braking device, more particularly to a braking device for a motor of an actuator. 
       BACKGROUND 
       [0002]    Linear actuators mainly use electric motors and actuating elements, such as worm gears and worm wheels, to actuate leadscrews rotating. Meanwhile, the leadscrews actuate telescopic tubes screwed thereof extending out or retracting. Since the structure and the assembly are simpler and more convenient than pneumatic cylinders or hydraulic cylinders, the linear actuators are widely used in apparatuses, such as sickbeds, electric chairs and other fields that need expansion and retraction. 
         [0003]    Conventional linear actuators are disclosed in EP0662573B and WO2004-027290A2, wherein EP0662573B discloses that an actuator mainly comprises a worm gear, a leadscrew, and a worm wheel assembly fixed at one end of the leadscrew. The worm wheel assembly comprises a worm wheel, a coil spring surrounding the outer peripheral edge of a cylindrical annular body. WO2004-027290A2 seeks to solve the problem in the previous application that a great amount of heat is generated by the friction between the coil spring and the annular body during the movement, and it applies a heat conducting unit to dissipate heat. 
         [0004]    However, the coil spring in conventional linear actuator is fixed, and the cylindrical annular body rotates with the worm wheel, so that heat is generated by the friction between the coil spring and the cylindrical annular body. In addition, the cylindrical annular body is generally made of plastics, so that the heat would cause the cylindrical annular body melting or the coil spring being worn out rapidly. Thus, the lifespan is greatly decreased. Also, the braking effect is achieved merely by linear contact between the coil spring and the cylindrical annular body, which is rotating, for decelerating or braking Since the effective contact areas between the coil spring and the annular body is small, the ability of decelerating or braking is limited. 
       SUMMARY 
       [0005]    One purpose of the disclosure is to provide a braking device for a motor of an actuator. The braking device retracts the coil spring by the elastic force of the elastic unit, so that the braking ring can have a stable braking effect. 
         [0006]    To reach this goal, the disclosure provides a braking device for a motor of an actuator. The motor of an actuator comprises a shaft. The braking device comprises a base, an elastic unit, a braking mechanism and a stopper. The base includes an axial connected section and a placed section formed at a lateral side of the axial connected section; the elastic unit is disposed at the placed section; the braking mechanism is assembled at the axial connected section, the braking mechanism comprises a braking ring sleeved on the shaft and a coil spring tightened to the outer peripheral edge of the braking ring, a first torque arm and a second torque arm extend from the two ends of the coil spring, and the first torque arm abuts one end of the elastic unit; the topper corresponds to the rotational path of the second torque arm and is disposed at the base. 
         [0007]    Moreover, the disclosure may also achieve the following effects. The disclosure assembles the elastic unit, the braking mechanism and the stopper inside the body in advance, so that the assembly process and assembly time of the braking device and the motor of the actuator can be greatly reduced. The braking device can be used in motors of actuators with different braking forces by the use of the adjusting lever. When the braking device of the disclosure is used for the linear actuator, the linear actuator can decline in a steady velocity, so that the user can have comfortable experience. The braking device of the disclosure further has advantages of a simple structure, low costs and a small size. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The disclosure will become more fully understood from the detailed description and the drawings given herein below for illustration only, and thus does not limit the disclosure, wherein: 
           [0009]      FIG. 1  is an exploded perspective view of a braking device according to the disclosure; 
           [0010]      FIG. 2  is a combinational view of the braking device according to the disclosure; 
           [0011]      FIG. 3  is an exploded view of the braking device used for a motor of an actuator of the disclosure; 
           [0012]      FIG. 4  is a combinational view of the braking device used for a motor of an actuator of the disclosure; 
           [0013]      FIG. 5  is a combinational sectional view of the braking device used for a motor of an actuator of the disclosure; 
           [0014]      FIG. 6  is a schematic view of a first using status of the braking device used for a motor of an actuator of the disclosure; 
           [0015]      FIG. 7  is a schematic view of a second using status of the braking device used for a motor of an actuator of the disclosure; 
           [0016]      FIG. 8  is a combinational view of the braking device according to another embodiment of the disclosure; and 
           [0017]      FIG. 9  is an external view of the braking ring of the braking device according to another embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
         [0019]    Referring to  FIGS. 1 and 2 , the disclosure provides a braking device used for a motor of an actuator. The braking device  1  mainly comprises a base  10 , an elastic unit  20 , a braking mechanism  30  and a stopper  40 . 
         [0020]    The base  10  can be made of plastics, and it mainly comprises a circular sector shaped bottom plate  11  and a hoarding  12  extending upward from the peripheral edge of the bottom plate  11 . The middle section of the bottom plate  11  has an axial connected section  13 . The axial connected section  13  is a hole  131  set up at the bottom plate  11  and a curve wall  132  extending from the peripheral edge of the hole  131 . Also, a placed section  14  is formed at a lateral side of the axial connected section  13 , and the placed section  14  is a semi-cylindrical barrel  141  formed between the bottom plate  11  and the hoarding  12 . Further, a vertical column  15  extends from the bottom plate  11  and the vertical column  15  is disposed at the front end of the semi-cylindrical barrel  141  and corresponds to a notch of a curve wall  132 . In addition, a fixed column  16  is disposed at the side of the semi-cylindrical barrel  141  and the vertical column  15 , such that screwed units, such as bolts, can pass through and fix with it. 
         [0021]    In this embodiment, the elastic unit  20  is a compressive elastic unit, and it mainly comprises a gliding unit  21  and a compressive spring  22 . The gliding unit  21  comprises a cylinder  211  and a protrusion  212  extending from the cylinder  211 . The cylinder  211  is movably disposed inside the semi-cylindrical barrel  141 . The compressive spring  22  is disposed inside the semi-cylindrical barrel  141  and is elastically clamped between the hoarding  12  and the cylinder  211 . 
         [0022]    The braking mechanism  30  is assembled at the axial connected section  13  of the base  10 , and it mainly comprises a braking ring  31  and a coil spring  32  tightened to the outer peripheral edge of the braking ring  31 . The braking ring  31  can be made of metals or plastics. In this embodiment, the braking ring  31  comprises three curve plates  311 . The inner wall of each of the curve plates  311  has an oil storage tank  312  disposing therein, and each of the oil storage tanks  312  corresponds to the axial direction of the curve plates  311 . Also, each of the outer walls of the curve plates  311  has a plurality of grooves  313 , and each of the plurality of grooves  313  is disposed corresponding to the radial direction of the plurality of curve plates  311 . Thus, the coil spring  32  can be fixed with each of the curve plates  311  stably. 
         [0023]    A first torque arm  321  and a second torque arm  322  extend from the two ends of the coil spring  32 . The first torque arm  321  is disposed between the protrusion  212  of the gliding unit  21  and the vertical column  15 , and the first torque arm  321  is abutted by the protrusion  212 . Under the free status, the angle A between the first torque arm  321  and the second torque arm  322  is between 10° and 50°. Preferably, the angle A is between 20° and 40°. Most preferably, the angle A is 30°. When the angle A is greater than 50° or when the angle A is smaller than 10°, the breaking force is too large or too small so that it cannot be applied. 
         [0024]    Moreover, a stop lever  323  folds inwardly from the free end of the second torque arm  322 . The stop lever  323  passes into the intervals formed between any two adjacent curve plates  311 , so as to prevent the curve plates  311  swinging excessively. 
         [0025]    In this embodiment, the stopper  40  is a fixed stopper  40 , and it corresponds to the rotational path of the second torque arm  322  and is fixed to the bottom plate  11  of the base  10 . 
         [0026]    Referring to  FIGS. 3-5 , the braking device  1  of the disclosure can be used for a motor  7  of an actuator. The motor  7  of the actuator comprises a shaft  71  and has a screw hole  72 . For assembling, the braking ring  31  of the braking mechanism  30  is sleeved corresponding to the shaft  71 , the end surface of the hoarding  12  attaches the back end surface of the motor  7  of the actuator, and a bolt passes through the fixed column  16  so as to be fixed to the screw hole  72 . Thus, the assembling process of the braking device  1  and the motor  7  of the actuator of the disclosure can be easily accomplished. 
         [0027]    As shown in  FIGS. 6 and 7 , when being used, the rotational direction of the shaft  71  is identical to the rotational direction of the coil spring  32 , wherein “identical” indicates that when the coil spring  32  is a right-handed coil spring and the shaft  71  rotates counterclockwise, the first torque arm  321  of the coil spring  32  is elastically abutted by the elastic unit  20 , so that the coil spring  32  retracts radially and tightens the braking ring  31 , and the braking action is generated by the friction between the inner surface of the braking ring  31  and the circumferential surface of the shaft  71 . When the coil spring  32  retracts radially, the second torque arm  322  swings with the rotation of the braking ring  31 . When the second torque arm  322  rotates to the position of the stopper  40 , it has a maximum braking force so that the shaft  71  stops rotating. Thus, when the motor  7  of the actuator is used in a linear actuator (not shown in the figure) and the linear actuator is assembled in an electric bed or an electric chair, the downward movement of the deck or the seat back would become more slowly, so that the user can have more comfortable using experience. 
         [0028]    In contrast, when the shaft  71  rotates clockwise, the first torque arm  321  of the coil spring  32  attaches the vertical column  15 , so that the coil spring  32  expands radially. At this moment, the braking ring  31  is released, so that the friction to the rotation of the shaft  71  is decreased, and the shaft  71  can easily rotate inside the braking ring  31 . Thereby, it can transmit without affecting the performance of transmission of the motor  7  of the actuator. 
         [0029]    Referring to  FIG. 8 , the braking device  1   a  further comprises an adjusting lever  50 , the hoarding  12  of the base  10  has a screw hole  121 . The adjusting lever  50  screws to the screw hole  121  and then is connected with the stopper  40 , so that the stopper  40  can move forwardly or backwardly by screwing-in or screwing-out the adjusting lever  50 . Thus, it can be used in motors  7  of the actuator with different braking forces. 
         [0030]    As shown in  FIG. 9 , besides the embodiments described above, the braking ring  31 ′ of the disclosure mainly has a sectional groove  33  at a cylindrical barrel, and the sectional groove  33  is parallel to the axis of the braking ring  31 ′. 
         [0031]    According to the above descriptions, the braking device used for a motor of the actuator of the disclosure can achieve the purposes and solve the problems met in conventional technologies. Thus, the disclosure involves novelty and inventiveness as well as meets the requirements of patent application. Thus, the application is applied according to Patent Law. The application is kindly requested to be granted for ensuring the right of the inventors.