Patent Publication Number: US-8987622-B2

Title: Switch

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2012-207493, filed on Sep. 20, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiment discussed herein is directed to a switch. 
     BACKGROUND 
     Conventional switches used in electrical transformation installations or the like include a gas insulated switch. An example of such a switch is a known switch in which a common operating device causes a first contact, which switches between the open state and the closed state, and a second contact, which switches between the open state and the ground state, to perform a switching operation. 
     Literature related to the above conventional technology includes, for example, Japanese Patent Application Laid-open No. 2011-146199. 
     Conventional switches, including the switch disclosed in the above literature, manually or automatically switch between the open state, the closed state, and the ground state, and there is still room for improvement in the mechanism that ensures the switching operation to be performed, such as a reduction in size. 
     SUMMARY 
     The switch according to an aspect of the embodiment includes a first contact that switches between an open state and a closed state, a second contact that switches between an open state and a ground state, an operating lever, and a rotating member that rotates for a predetermined angle in accordance with an operation of the operating lever. Furthermore, the switch includes a first cam that opens and closes the first contact by rotating in conjunction with a rotation of the rotating member in one direction and a second cam that opens and closes the second contact by rotating in conjunction with a rotation of the rotating member in another direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an explanatory diagram illustrating the appearance of a switch according to an embodiment. 
         FIG. 2  is a circuit diagram of the switch. 
         FIG. 3  is an explanatory diagram illustrating an operating unit of the switch. 
         FIG. 4  is an explanatory diagram illustrating the internal structure of the whole switch. 
         FIG. 5  is an explanatory diagram illustrating a cam mechanism of the operating unit. 
         FIG. 6A  is a perspective view of the cam mechanism as viewed from one side direction. 
         FIG. 6B  is a perspective view of the cam mechanism as viewed from the other side direction. 
         FIG. 7  is an explanatory diagram illustrating an operating state of the cam mechanism. 
         FIG. 8  and  FIG. 9  are schematic explanatory diagrams illustrating an example of the operation of a toggle mechanism of the operating unit. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of a switch disclosed in the present application will be explained in detail with reference to the drawings.  FIG. 1  is an explanatory diagram illustrating the appearance of a switch  10  according to the embodiment.  FIG. 2  is a circuit diagram of the switch  10 .  FIG. 3  is an explanatory diagram illustrating an operating unit  4  of the switch  10  and  FIG. 4  is an explanatory diagram illustrating the internal structure of the whole switch  10 . In the following, an explanation will be given of a case where the switch  10  is, for example, an earth switch provided underground; however, this invention is not limited to this embodiment. 
     As illustrated in  FIG. 1 , the switch  10  according to the present embodiment includes a rectangular box-shaped casing  20  fixed on an arrangement frame  30  and includes therein a switching device  11  represented by the circuit illustrated in  FIG. 2 . Specifically, the switching device  11  is provided with a switching unit  3 , which includes a first contact  31  and a second contact  32 , in the middle of the circuit that connects between a first feeder  1  and a second feeder  2 . The first contact  31  switches between the open state and the closed state. The second contact  32  switches between the open state and the ground state. Normally, when maintenance is performed on the switch  10 , the second contact  32  is closed so as to be in the ground state. 
     The casing  20  of the switch  10  according to the present embodiment is filled with an insulating gas. As illustrated in  FIG. 3 , the switching device  11 , which includes a first switching device  11   a , a second switching device  11   b , and a third switching device  11   c  corresponding to three phases (U phase, V phase, and W phase), respectively, is accommodated in the casing  20 . In this embodiment, SF 6  (sulfur hexafluoride) is used as the insulating gas; however, it can be appropriately selected. 
     The switching devices  11   a  to  11   c  are arranged in parallel in the longitudinal direction of the casing  20  and each include the first contact  31  and the second contact  32  as the switching unit  3 . The switching devices  11   a  to  11   c  are operatively connected to the operating unit  4  that opens and closes the first contact  31  and the second contact  32 . In the present embodiment, each of the switching devices  11   a  to  11   c  is generically referred to as the switching device  11  in some cases. 
     As illustrated in  FIG. 1 , the first feeder  1  and the second feeder  2  to be a main wiring are connected to a main surface  101  on one side of the casing  20  for each of the three phases (U phase, V phase, and W phase). A rotating shaft  40   a , which is operatively connected to the switching devices  11   a  to  11   c , is rotatably provided in a projecting manner on a side surface  102  on one side of the casing  20 . 
     As illustrated in  FIG. 1  and  FIG. 3 , the base end portion of an operating lever  6  is attached to the rotating shaft  40   a  such that the rotating shaft  40   a  can be rotated from the outside. Specifically, while a connection hole  62  is formed in the base end portion of the operating lever  6 , a circular wire connection hole  61  is formed in the tip portion of the operating lever  6  and one end of an operating wire  7  extending upward is connected to the wire connection hole  61 . 
     The rotating shaft  40   a  can be rotated via the operating lever  6 , for example, by pulling up the operating wire  7  extended toward the ground. As illustrated in  FIG. 1 , an indicating unit  14   a , which indicates the switching condition of the first contact  31 , and an indicating unit  14   b , which indicates the switching condition of the second contact  32 , are provided on the side surface  102 . 
     The operating lever  6  can be mounted, as illustrated in  FIG. 1 , selectively in a first mounted state (indicated by the solid line) and a second mounted state (indicated by the dashed line), which is shifted approximately 90° counterclockwise from the first mounted state. In other words, the connection hole  62  can be connected in any of the first mounted state, which defines the rotation direction of a rotating member  40  of a cam mechanism  4 A to be described later in a first direction, and the second mounted state, which defines the rotation direction of the rotating member  40  in a second direction. Specifically, the tip of the rotating shaft  40   a  is processed into a rectangular shape (see  FIG. 5 ) and the connection hole  62  of the operating lever  6  is formed into a rectangular shape corresponding to the rotating shaft  40   a.    
     In this embodiment, the switching device  11  can be set to on (closed circuit) in the first mounted state and the switching device  11  can be grounded in the second mounted state. In other words, it is possible to switch between the open state and the closed state with the first contact  31  in the first mounted state and switch between the open state and the ground state with the second contact  32  in the second mounted state. 
     It is not common to set the switching device  11  to the ground state; therefore, as illustrated in  FIG. 1  and  FIG. 4 , a lock key  9  needs to be released to set the operating lever  6  to the second mounted state so that the operating lever  6  is not set to the second mounted state by mistake. As illustrated in  FIG. 4 , in a non-use state, the operating lever  6  can be stored by being hooked on a pin-like hook  103  provided on the side surface  102  of the casing  20 . 
     Eye bolts  21  for suspending the switch  10  are attached at four corners of a top surface  104  of the casing  20 . A wire guide  71 , which guides the operating wire  7 , is provided to extend between two of the eye bolts  21  and  21  located on the side surface  102  side on which the rotating shaft  40   a  is provided in a projecting manner. 
     The configuration of the operating unit  4  including the rotating shaft  40   a  and the operating lever  6  described above and the operation of the switching device  11  via the operating unit  4  will be described with reference to  FIG. 3  to  FIG. 9 .  FIG. 5  is an explanatory diagram illustrating the cam mechanism  4 A of the operating unit  4 .  FIG. 6A  is a perspective view of the cam mechanism  4 A as viewed from one side direction,  FIG. 6B  is a perspective view of the cam mechanism  4 A as viewed from the other side direction, and  FIG. 7  is an explanatory diagram illustrating an operating state of the cam mechanism  4 A. 
     As illustrated in  FIG. 3  and  FIG. 4 , the switching device  11   a ,  11   b , and  11   c  accommodated in the casing  20  each include the first contact  31  and the second contact  32 . The first contact  31  can switch between the open state and the closed state by being separated from and coming into contact with a pin-like first switching member  33   a , and the second contact  32  can switch between the open state and the ground state by being separated from and coming into contact with a pin-like second switching member  33   b.    
     The first switching member  33   a  and the second switching member  33   b  are arranged coaxially with each other in substantially the vertical direction, and the first switching member  33   a  is connected to a first transmission shaft  34   a  and the second switching member  33   b  is connected to a second transmission shaft  34   b . In  FIG. 4 , the first and second transmission shafts  34   a  and  34   b  are not shown. 
     The operating unit  4  is a mechanism that rotates the first transmission shaft  34   a  and the second transmission shaft  34   b  around the shaft center. In other words, the operating unit  4  includes the operating lever  6  and the rotating shaft  40   a  that rotates for a predetermined angle in accordance with the operation of the operating lever  6 , and moreover includes the cam mechanism  4 A that includes the rotating member  40  fixed to the rotating shaft  40   a.    
     As illustrated in  FIG. 5  and  FIGS. 6A and 6B , the cam mechanism  4 A includes a first cam  41  and a second cam  42 . The first cam  41  opens and closes the first contact  31  by rotating in conjunction with the rotation of the rotating member  40  in one direction (in this embodiment, clockwise). The second cam  42  opens and closes the second contact  32  by rotating in conjunction with the rotation of the rotating member  40  in the other direction (counterclockwise). The state of the cam mechanism  4 A illustrated in  FIG. 5  is a neutral state where both the first contact  31  and the second contact  32  are open. Herein, a first switching means corresponds to, for example, the first cam  41  and the first contact  31  and is a means for switching between an open state and a closed state. A second switching means corresponds to, for example, the second cam  42  and the second contact  32  and is a means for switching between an open state and a ground state. Moreover, an operating means corresponds to, for example, the operating lever  6  and the rotating member  40 . The operating means is a means for selecting one of the first switching means and the second switching means, causing only the first switching means to operate in a case where the selected means is the first switching means, and causing only the second switching means to operate in a case where the selected means is the second switching means. In this case, when the selected means is changed, the selected means is changed to the first switching means or the second switching mean via the open state. 
     The first cam  41  is fixed to a first rotating shaft  410  and the second cam  42  is fixed to a second rotating shaft  420 . The first cam  41  and the second cam  42  are arranged to face each other with the rotating member  40  therebetween such that the first rotating shaft  410 , the second rotating shaft  420 , and the rotating shaft  40   a  of the rotating member  40  are located substantially along the same straight line. In  FIGS. 6A and 6B , the rotating shaft  40   a , the first rotating shaft  410 , and the second rotating shaft  420  are not shown, and, as illustrated in  FIGS. 6A and 6B , a rotating shaft connection hole  404  is provided in the rotating member  40  and rotating shaft connection holes  413  and  423  are provided in the first cam  41  and the second cam  42 , respectively. 
     The rotating member  40  is formed into substantially a disk shape with the rotating shaft  40   a  (the rotating shaft connection hole  404 ) as the center and is provided with an engaging portion  400 , which is engaged with the first cam  41  and the second cam  42 , along substantially half the outer periphery. In other words, first to fourth engaging pins  405   a  to  405   d  are provided in a projecting manner along substantially half the outer periphery of the rotating member  40 . A first recessed portion  401  is formed between the adjacent first and second engaging pins  405   a  and  405   b . In a similar manner, a second recessed portion  402  is formed between the second and third engaging pins  405   b  and  405   c  and a third recessed portion  403  is formed between the third and fourth engaging pins  405   c  and  405   d.    
     Moreover, a first engaging recessed portion  411 , which is engaged with the first engaging pin  405   a , and a second engaging recessed portion  412 , which is engaged with the second engaging pin  405   b , are formed in the first cam  41 . Furthermore, a first engaging recessed portion  421 , which is engaged with the fourth engaging pin  405   d , and a second engaging recessed portion  422 , which is engaged with the third engaging pin  405   c , are formed in the second cam  42 . 
     Moreover, the first rotating shaft  410 , to which the first cam  41  is fixed, is operatively connected to the first transmission shaft  34   a  via a first toggle mechanism  4 B 1  to be described later (see  FIG. 3  and  FIG. 4 ). Furthermore, the second rotating shaft  420 , to which the second cam  42  is fixed, is operatively connected to the second transmission shaft  34   b  via a second toggle mechanism  4 B 2  to be described later (see  FIG. 3  and  FIG. 4 ). 
     With this configuration, when the rotating member  40  rotates clockwise, first, the first engaging pin  405   a  is engaged with the first engaging recessed portion  411  of the first cam  41  and then the second engaging pin  405   b  is engaged with the second engaging recessed portion  412 , thereby rotating the first cam  41  counterclockwise. 
     In contrast, when the rotating member  40  rotates counterclockwise, first, the fourth engaging pin  405   d  is engaged with the first engaging recessed portion  421  of the second cam  42  and then the third engaging pin  405   c  is engaged with the second engaging recessed portion  422 , thereby rotating the second cam  42  clockwise. 
     Moreover, in the present embodiment, as illustrated in  FIG. 3 , a motor  8  that is a drive source, which is operatively connected to the first cam  41 , is included. Specifically, the first cam  41  can be directly rotated by power transmission from the motor  8  via a not-shown speed reducer without using the rotating member  40  that rotates in conjunction with the operation of the operating lever  6 . In other words, the switch  10  according to the present embodiment can perform switching between the open state and the closed state by directly rotating the first cam  41  by remotely driving the motor  8 . The motor  8  is one example of a drive means, and the drive means is not limited to a motor and may be an actuator, such as an air cylinder or a hydraulic cylinder. Herein, the motor  8  corresponds to a drive means for directly operating the first switching means without using the operating means that includes the rotating member  40 . 
     In contrast, the switching between the open state and the ground state is restricted such that it is only performed by a manual operation using the operating lever  6 . 
     Moreover, the first cam  41  includes a stopper that restricts the rotation of the first cam  41 . In other words, as illustrated in  FIG. 5  to  FIG. 6B , a stopper pin  43  is provided in a projecting manner on the first cam  41  between the first engaging recessed portion  411  and the second engaging recessed portion  412  in a direction opposite to the first to fourth engaging pins  405   a  to  405   d  of the rotating member  40 . The stopper pin  43  restricts the rotation of the first cam  41  by coming into contact with the rotating member  40  under a predetermined condition. The shape of the stopper is not limited to a pin shape, such as the shape of the stopper pin  43 , and it is sufficient that the stopper has a projected shape to function as a stopper by coming into contact with the rotating member  40 . 
     In the present embodiment, the predetermined condition is that, in the ground state in which the second contact  32  is closed, the force that rotates the first cam  41  in a direction that sets the first contact  31  to the closed state is acting forcibly. Therefore, in this case, the stopper pin  43  can restrict the rotation of the first cam  41  by coming into contact with the rotating member  40 . In this case, the first switching means includes an operation restricting means for restricting an operation of the first switching means when a force, which causes the first switching means to operate in a direction that closes the first switching means so as to be in a closed state, is applied forcibly to the first switching means in a state where the current state is the ground state. Herein, the operation restricting means corresponds to the stopper pin  43  that is a stopper. 
     In other words, in the ground state in which the second contact  32  is closed, as illustrated in  FIG. 7 , the cam mechanism  4 A is in a state where the rotating member  40  rotates approximately 90° counterclockwise from the neutral state in  FIG. 5  and the second cam  42  rotates approximately 90° clockwise. On the other hand, the first cam  41  is not changed from the neutral state in  FIG. 5 . 
     A case is considered where a command signal is sent to the motor  8  from the outside, for example, due to erroneous operation, and, as described above, the force that rotates the first cam  41  in a direction (counterclockwise) that closes the first contact  31  is applied to the first cam  41  by the motor  8  from the state illustrated in  FIG. 7 . In this case, as illustrated in  FIG. 7 , because the stopper pin  43  comes into contact with the peripheral surface of the rotating member  40 , further rotation of the first cam  41  is prevented. In the present embodiment, when the rotation of the first cam  41  is restricted, for example, for 2 seconds, transmission of a command signal to the motor  8  is controlled to be stopped. 
     In the present embodiment, because the first cam  41  and the second cam  42  are formed by using the same members, the stopper pin  43  is also provided in a projecting manner on the second cam  42 ; however, the stopper pin  43  provided in a projecting manner on the second cam  42  may be absent. 
     Moreover, the operating unit  4  includes a toggle mechanism  4 B (the first toggle mechanism  4 B 1  and the second toggle mechanism  4 B 2 ). The toggle mechanism  4 B can instantaneously drive the first switching member  33   a  and the second switching member  33   b , which are provided to be able to come into contact with and separate from the first contact  31  and the second contact  32 , in the closing direction in cooperation with the cam mechanism  4 A.  FIG. 8  and  FIG. 9  are schematic explanatory diagrams illustrating an example of the operation of the toggle mechanism  4 B of the operating unit  4 , in which  FIG. 8  illustrates the operation of the first toggle mechanism  4 B 1  and  FIG. 9  illustrates the operation of the second toggle mechanism  4 B 2 . 
     As illustrated in  FIG. 8 , the operating unit  4  of the switch  10  includes the first toggle mechanism  4 B 1 , which is operatively connected to the first transmission shaft  34   a  connected to the first switching members  33   a , which open and close the first contacts  31 , and which is operatively connected to the first rotating shaft  410 , to which the first cam  41  is fixed. Moreover, as illustrated in  FIG. 9 , the operating unit  4  includes the second toggle mechanism  4 B 2 , which is operatively connected to the second transmission shaft  34   b  connected to the second switching members  33   b , which open and close the second contacts  32 , and which is operatively connected to the second rotating shaft  420 , to which the second cam  42  is fixed. 
     First, the configuration and the operation of the first toggle mechanism  4 B 1  will be described. As illustrated in  FIG. 8 , the first toggle mechanism  4 B 1  is such that a first plate  45  is fixed to a connecting shaft  451  that is operatively connected to the first rotating shaft  410  of the first cam  41 . Moreover, a second plate  46  is rotatably provided to the connecting shaft  451 . Furthermore, as illustrated in  FIG. 8 , a spring  48  is stretched between a shaft body  452  provided at the tip portion of the first plate  45  and a shaft body  461  provided at one end of the second plate  46  that faces the shaft body  452  with a third plate  47  therebetween. 
     Moreover, the second plate  46  is formed to be able to interact with the third plate  47  that supports the first transmission shaft  34   a . For example, when the first transmission shaft  34   a  is in a first posture ((a) and (b) of  FIG. 8 ), the first switching member  33   a  is in the open state, and when the first transmission shaft  34   a  takes a second posture ((c) of  FIG. 8 ), the first switching member  33   a  comes into contact with the first contact  31  so as to be in the closed state. 
     Moreover, a first sprocket  83  is fixed to the connecting shaft  451  of the first toggle mechanism  4 B 1  along with the first plate  45  and an endless chain  81  is wound between the first sprocket  83  and a second sprocket  82  fixed to a drive shaft  80  of the motor  8 . Therefore, when the motor  8  is driven, the connecting shaft  451  can be rotated via the first sprocket  83 , and as a result, the first plate  45  can be rotated. 
     The operation of the first toggle mechanism  4 B 1  in the case of switching from the open state to the closed state will be described. For closing the first contact  31 , the motor  8  is driven from the initial state illustrated in (a) of  FIG. 8  to rotate the first plate  45  counterclockwise as illustrated in (b) of  FIG. 8 . 
     Then, the spring  48  stretched between the first plate  45  and the second plate  46  is gradually extended and the maximum tension occurs in the state illustrated in (b) of  FIG. 8 . When the first plate  45  is further rotated counterclockwise due to the driving of the motor  8 , the spring  48  exceeds the dead point and the spring  48  rapidly contracts. With the contraction of the spring  48 , the second plate  46  formed to be able to interact with the third plate  47  instantaneously rotates clockwise around the shaft body  461  and swings the first transmission shaft  34   a  counterclockwise as illustrated in (c) of  FIG. 8 . With this sequence of operations, the first switching member  33   a  operatively connected to the first transmission shaft  34   a  comes into contact with the first contact  31  so as to be in the closed state. In the present embodiment, switching is performed by using the motor  8 ; however, it is also possible to perform switching from the open state to the closed state via the cam mechanism  4 A by using the operating lever  6  to manually rotate the rotating member  40  clockwise without using the motor  8 . 
     Next, the operation of the second toggle mechanism  4 B 2  in the case of switching from the open state to the ground state will be described with reference to  FIG. 1 ,  FIG. 3 , and  FIG. 9 . Although the second toggle mechanism  4 B 2  is different from the first toggle mechanism  4 B 1  in that it is not connected to the motor  8 , the basic structure of the second toggle mechanism  4 B 2  is the same as that of the first toggle mechanism  4 B 1 ; therefore, the components that achieve the same function as those of the first toggle mechanism  4 B 1  are denoted by the same reference numerals and an explanation of the configuration thereof is omitted. 
     The posture of the second transmission shaft  34   b  in (a) and (b) of  FIG. 9  is a first posture, in which the second switching member  33   b  is in the open state. In contrast, the posture of the second transmission shaft  34   b  illustrated in (c) of  FIG. 9  is a second posture. When the second transmission shaft  34   b  takes the second posture, the second switching member  33   b  comes into contact with the second contact  32  so as to be in the ground state. 
     The operation of the second toggle mechanism  4 B 2  in the case of switching from the open state to the ground state will be described. For switching from the open state to the ground state, a manual operation by using the operating lever  6  is performed. 
     First, the operating lever  6  is reattached to the rotating shaft  40   a  of the rotating member  40  such that the operating lever  6  is in the first mounted state indicated by the dashed line in  FIG. 1 . Then, the operating lever  6  is rotated counterclockwise by pulling up the operating wire  7 , thereby rotating the rotating member  40  of the cam mechanism  4 A counterclockwise. Consequently, the second cam  42  rotates clockwise (see  FIG. 3 ,  FIG. 5 , and  FIG. 7 ) and the first plate  45  also rotates clockwise, as illustrated in (b) of  FIG. 9 , from the initial state illustrated in (a) of  FIG. 9 . 
     Then, the spring  48  stretched between the first plate  45  and the second plate  46  is gradually extended and the maximum tension occurs in the state illustrated in (b) of  FIG. 9 . When the operating lever  6  is further raised, the first plate  45  further rotates clockwise and the spring  48  exceeds the dead point. Then, the spring  48  rapidly contracts. With the contraction of the spring  48 , the second plate  46  instantaneously rotates counterclockwise around the shaft body  461  and swings the second transmission shaft  34   b  clockwise as illustrated in (c) of  FIG. 9 . With this sequence of operations, the second switching member  33   b  operatively connected to the second transmission shaft  34   b  comes into contact with the second contact  32  so as to be in the ground state. 
     The switch  10  according to the present embodiment described above can perform switching between the open state and the closed state of the first contact  31  and between the open state and the ground state of the second contact  32  also by using one operating lever  6  with a simple mechanism. Therefore, the switch  10  buried underground can be reduced in size, have excellent operability, and have high reliability. 
     The switch  10  has been described above through the embodiment; however, for example, the configuration of the cam mechanism  4 A and the toggle mechanism  4 B of the operating unit  4 , and the like can appropriately changed. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.