Embodiments of the present invention relate to a DC circuit breaker.
Recently, high-voltage DC power supplies have been used in temperature control devices for cooling electric circuits such as cooling and heating devices provided in the room of electric vehicles and batteries. In such devices, when abnormal current flows through the circuit due to collision accidents, it may lead to serious accidents such as firing due to the heat caused by overcurrent. Thus, DC circuit breakers were required in these devices to reliably cut off current. It is also required for these DC circuit breakers to be compact and simply structured when they are installed in a limited space such as an engine room of an automobile because it is difficult to secure installation space.
However, in order to reliably extinguish arc generated when cutting off high-voltage DC current in such DC circuit breakers, it was required to, for example, separate the contacts by a sufficient distance or provide an arc extinguisher to disperse the generated arc. It was therefore difficult to reduce the size of the circuit breaker. Further, the components of the circuit breaker become smaller with the downsizing of the circuit breaker. As a result, it becomes difficult to assemble the circuit breaker which tends to reduce productivity.
Thus, there is provided a DC circuit breaker capable of reliably cutting off high-voltage DC current and which is further downsized and improved in productivity.
A DC circuit breaker of an embodiment is provided with a case formed of an electrically insulative material; two fixed contacts fixed within the case; two movable contacts each provided so as to correspond to each of the two fixed contacts; a bypass plate having the two movable contacts fixed thereto and electrically connecting the two movable contacts; a moving block having a groove in which the bypass plate is disposed and being provided so as to be movable in a direction to move away from the fixed contacts within the case, the moving block being configured to move the bypass plate in a direction to move away from the fixed contacts when moving in the direction to move away from the fixed contacts; a moving block biasing member configured to constantly bias the moving block in the direction to move away from the fixed contacts; a thermally responsive member provided in a position opposing an installation surface and configured to deform when the installation surface becomes equal to or greater than a prescribed temperature; a latch having a locking portion configured to restrict movement of the moving block by locking the moving block when the thermally responsive member is in a pre-deformation state, the latch being configured to operate to cancel the restriction of the movement of the moving block by unlocking the locking portion from the moving block in response to a deformation of the thermally responsive member; a shutter formed of an electrically insulative material and configured to be inserted between the fixed contacts and the movable contacts when the movable contacts are separated from the fixed contacts; and a shutter biasing member configured to constantly bias the shutter in a direction to be inserted between the fixed contacts and the movable contacts.
An embodiment will be described hereinafter with reference to the drawings.
A description will be given on one example of a construction of a DC circuit breaker 10 according to an embodiment. The DC circuit breaker 10 is a thermally responsive DC circuit breaker and operates to cut off current when abnormal heating is detected by the host device. As shown in
The case 20 constitutes the outer housing of the DC circuit breaker 10 and is formed of electrically insulative material such as resin. Electrically insulative resin such as PPS (Polyphenylene sulfide) resin, UP (unsaturated polyester), PBT (polybutyleneterephtalate), and ABS; and inorganic insulating material such as ceramics, for example, are selected as appropriate as the material of the case 20 depending upon the environment in which the DC circuit breaker 10 is used. The case 20 is divided into multiple, in this case, two cases. In this example, the case 20 is configured by a combination of a first case 21 and a second case 22.
As shown in
The wire connector 32 is configured, for example, as a hole extending through the terminal plate 31 and is exposed from the case 20. The wire connector 32 may be formed as a hole with or without a female thread. The wires of the device whose circuit is to be cut off by the circuit breaker 10 are connected to the wire connector 32. For example, the wires of the device are provided with a male thread terminal which is threaded into the wire connector 32 or is secured to the wire connector 32 by being fastened by a nut. The wire connector 32 may be provided, for example, with a terminal such as a male thread or a stud terminal.
The fixed contact 33 is formed of an electrically conductive material primarily composed of silver for example. Clad materials such as silver oxide and copper or copper alloy are selected as appropriate as the material of the fixed contact 33 depending upon the environment in which the DC circuit breaker 10 is used. The fixed contact 33 is fixed to the terminal plate 31 so as to face the direction opposite the wire connector 32. Thus, the fixed contact 33 is fixed so as to be stored inside the case 20, in this example, inside the first case 21. The fixed contact 33 is configured so as to be unmovable within the case 20.
As shown in
The movable contact 42 is formed of an electrically conductive material such as copper and copper alloy as was the case for the fixed contact 33. The two movable contacts 42 are each fixed to each of the two ends provided at the longer side direction of the bypass plate 41. Each of the movable contacts 42 face the fixed contact 33 as viewed from the bypass plate 41. The moving block 43 is stored so as to be movable within the case 20, in this example, within the first case 21. In the present embodiment, the moving block 43 is configured to be movable, for example, in the downward direction as viewed in the page of
As shown in the drawings such as
The protrusion 212 is provided on a surface located on a terminating side of the moving block 43 and protrudes toward the moving block 43. In the present embodiment, the first case 21 is provided with two protrusions 212. The two protrusions 212 are provided at positions symmetrical to a plane passing through the center of gravity of the moving block 43 and extending along the direction of movement of the moving block 43. That is, the two protrusions 212 are provided in positions symmetrical to the lateral center of the moving block 43 as viewed in
As shown in
The U-shaped curved portion 411 of the bypass plate 41 has parallelly disposed linear portions that extend along the moving direction of the moving block 43. The U-shaped groove 431 has linear portions extending along the moving direction of the moving block 43 and the linear portions of the curved portion 411 are inserted into the linear portions of the groove 431. Thus, when the bypass plate 41 tries to move in the direction orthogonal to the moving direction of the moving block 43, that is, in the lateral direction of the page of
In this example, the groove 431 is formed into a U shape. However, the groove 431 is not limited to a U shape conforming with the U shape of the curved portion 411 of the bypass plate as long as a gap can be created in the moving direction of the moving block 43 and the bypass plate 41 can be retained so as not to be removed from the moving block 43 by the bias of the contact pressing spring 44 when the contact is opened.
The cavities 432 are provided on a surface of the moving block 43 located on a side opposite the fixed contact 33, that is, on a surface located in the moving direction side of the moving block 43. The two cavities 432 each correspond to each of the two protrusions 212 provided on the first case 21. The protrusions 212 fit into the cavities 432 when the moving block 43 moves to the terminating position. It is thus, possible to prevent the moving block 43 from temporarily bouncing back toward the fixed contact 33 side when the moving block transports rapidly and impinges on the wall in the terminating side of the moving block housing 211. Hence, it is possible to prevent the distance between the fixed contact 33 and movable contact 42 from being reduced when the contacts are opened and thereby prevent the arc from being sustained or be regenerated after being once extinguished.
The pressing spring housing 433 is formed on the moving block 43 by cylindrically digging a surface of the moving block 43 in the movable contact 42 side towards the moving direction of the moving block 43. The pressing spring housing 433 stores and supports a part of the pressing spring 44. Two pressing spring housings 433 are each provided in a position corresponding to each of the two movable contacts 42. That is, the movable contacts 42 and the pressing spring housings 433 are disposed on the line extending along the moving direction of the moving block 43.
The separating spring housing 434 is formed on the moving block 43 by cylindrically digging a surface of the moving block 43 in the movable contact 42 side towards the moving direction of the moving block 43. The separating spring housing 434 stores and supports a part of the separating spring 45. The two separating spring housings 434 are disposed in a position displaced with respect to the direction in which the two pressing spring housings 433 are disposed. That is, each of the two separating spring housings 434 are disposed in a position displaced in the lateral direction which is orthogonal to the direction normal to the page of
The pressing spring 44 is formed of a compression coil spring, for example, and serves as a movable contact biasing member configured to bias the movable contact 42 provided at the bypass plate 41 in a direction to press the fixed contact 33. The pressure spring 44 are provided so as to correspond to the two movable contacts 42. The pressure spring 44 are provided on the bypass plate 41 so as to be located in the side opposite the fixed contacts 33 and are disposed between the bypass plate 41 and the moving block 43.
The pressing spring 44 is stored in the pressing spring housing 433 with a part of the pressing spring 44 protruding from the pressing spring housing 433. A first end of the pressing spring 44 is supported by the bottom of the pressing spring housing 433 and a second end of the pressing spring 44 supports a surface of the bypass plate 41 located on a side opposite the movable contacts 42. The pressing spring 44 is not limited to a compression coil spring as long as it is capable of biasing the movable contacts 42 provided at the bypass plate 41 in a direction to press the fixed contacts 33.
The separating spring 45 is formed of a compression coil spring, for example, and serves as a moving block biasing member configured to bias the moving block 43 in a direction moving away from the fixed contacts 33. That is, the separating spring 45 imparts moving force to the moving block 43, bypass plate 41, and the movable contacts 42 which moving force is exerted in a direction to move the moving block 43, the bypass plate 41, and the movable contacts 42 away from the fixed contacts 33.
The separating springs 45 are provided so as to correspond to the two movable contacts 42. The separating spring 45 is provided between the moving block 43 and the wall of the case 20. In this example, the separating spring 45 is provided between the moving block 43 and the wall of the first case 21. A first end of the separating spring 45 is supported by the bottom of the separating spring housing 434 and a second end of the separating spring 45 is supported by a wall provided within the moving block housing 211 of the first case 21. Thus, the separating spring 45 constantly biases the moving block 43 in a direction to move away from the fixed contacts 33.
The two separating spring housings 434 are each disposed in a position displaced from the gravity center of the moving block 43. Consequently, the separating spring 45 is also disposed in a position displaced from the gravity center of the moving block 43. When the elastic force of the pressing spring 44 is ignored, a rotational force having the gravity center of the moving block 43 as the rotational center is exerted on the moving block 43 by the elastic force received by the separating spring 45. As a result, the moving block 43 gets caught on the inner wall of the moving block housing 211 and thereby inhibits the smooth movement of the moving block 43.
Thus, in the present embodiment, the elastic force of the separating spring 45 is set so as to be less than the elastic force of the pressing spring 44. That is, the sum of the biasing force of the two pressure spring 44, serving as the movable contact biasing member, is set so as to be greater than the sum of the biasing force of the two separating springs 45, serving as the moving block biasing member. Thus, the pressing spring 44 exerts force oriented in a direction to cancel the rotational force exerted by the separating spring 45 in the initial stage of movement of the moving block 43. Consequently, rotation of the moving block 43 is suppressed in the initial stage of movement of the moving block 43. As a result, the moving block 43 is inhibited from being caught on the inner wall of the moving block housing 211 to allow smooth movement of the moving block 43.
The latch mechanism 50 is configured to control the behavior of the movable electrode mechanism 40, that is, the movement of the moving block 43. As shown in
As illustrated in the drawings such as in
The latch 51 is provided with a receiving portion 511 and a locking portion 512. The receiving portion 511 is provided on a first end of the L-shaped latch 51. The receiving portion 511 is configured to receive operating force of the latch 51 from the trigger mechanism 60. The locking portion 512 is provided on a second end of the L-shaped latch 51. The locking portion 512 is configured to lock the moving block 43. The moving block 43 is provided with a locked portion 435. The locked portion 435 is formed by notching a portion of a part located in the opposite side of the fixed contact 33 in a stepped shape. The latch 51 restricts the movement of the moving block 43 by the locking of the locking portion 512 of the latch 51 with the locked portion 435 of the moving block 43. When the latch 51 rotates in the direction indicated by the white box arrow shown in
As shown in
As shown in
The trigger mechanism 60 is provided in the installation surface 90 side of the DC circuit breaker 10. The trigger mechanism 60 operates the latch 51 to cancel the restriction of the moving block 43 when detecting the abnormal heating of the host device. As shown in
The pressing spring 62 is configured by a plate spring having a round hole formed through its central portion, for example and is provided between the case 20 and the thermally responsive member 61. The pressing spring 62 presses the thermally responsive member 61 towards the installation surface 90 at a load in the magnitude that does not inhibit the deformation of the thermally responsive member 61 by temperature variation. The pressing spring 62 is provided with four legs 621 and the legs 621 press the outer peripheral portion of the thermally responsive member 61 towards the installation surface 90. The number of legs may be three or five or more as long as it is possible to press the thermally responsive member 61 equally at a load in the magnitude that does not affect the operation of the thermally responsive member 61.
The cover 63 is formed of a material with high thermal conductivity, for example, metal material such as an aluminum alloy or copper alloy and is formed into a shallow cylindrical shape. The cover 63 is used to attach the thermal responsive member 61 to the case 20. The cover 63 holds the outer peripheral portion of the thermal responsive member 61 and is attached to the case 20 with the central portion of the thermally responsive member 61 exposed.
When a heating medium having high thermal conductivity and flexibility is provided on the surface of the installation surface 90, the thermally responsive member 61 may be completely covered by the cover 63.
In the present embodiment, the case 20 is provided with a thermally responsive member mount 201. The thermally responsive member mount 201 is formed into a shape that protrudes toward the installation surface 90 when the first case 21 and the second case 22 are put together. The external shape of the thermally responsive member mount 201 is the same as the external shape of the thermally responsive member 61. As shown in
The space 11 prevents the case 20 from touching the installation surface 90. Thus, the space 11 serves as a heat insulating layer that prevents transfer of heat from installation surface 90 to the case 20. The heat insulating effect of the space 11 makes it difficult for the case 20 to be affected by the heat from the installation surface 90. That is, it becomes difficult for the heat from the installation surface 90 to be transferred to portions other than the thermally responsive member 61. Thus, it becomes difficult for the thermally responsive member 61 from being affected by the heat accumulated in the case 20, for example. As a result, it becomes possible to detect change in the status of heat of the installation surface 90 more accurately. By delaying the heat transfer from the installation surface 90 to the case 20, it becomes possible to detect the change in the status of heat more reliably by effectively transferring the heat of the installation surface 90 to the thermally responsive member 61 when a sudden temperature elevation occurs. Thus, the DC circuit breaker 10 becomes capable of promptly conducting a cutoff operation when the temperature of the installation surface 90 becomes equal to or greater than a prescribed value.
As shown in
The shutter inserting spring 72 serves as a shutter biasing member that constantly biases the shutter 73 in a direction to be inserted between the fixed contact 33 and the movable contact 42. In the present embodiment, the shutter inserting spring 72 is configured by a torsion spring provided with a coil portion 721, a support arm 722, and an operating arm 723.
The coil portion 721 is a portion formed into a coil shape. The support arm 722 is provided on a first end of the coil portion 721 and is supported by the mounting member 71 or the case 20 which, in this example, is the second case 22. The operating arm 723 is provided on a second end of the coil portion 721 and exerts elastic force on the shutter 73. The shutter inserting spring 72 is mounted on the mounting member 71 with the coil portion 721 inserted into the support shaft 711 of the mounting member 71.
As shown in
It is preferable for the pre-operation angle θ1 and the post-operation angle θ2 to be equal to or less than 20 degrees when downsizing is considered. In the present embodiment, the pre-operation angle θ1 is set to 17 degrees and the post-operation angle θ2 is set to 18 degrees. As a result, the operating angle θ of the operating arm 23 amounts to 35 degrees.
The two shutters 73 correspond to the two fixed contacts 33 and movable contacts 42, respectively. Similar to the case 20, the shutter 73 is configured by a material having electrically insulativity such as resin. The material of the shutter 73 is selected as required from electrically insulative resin such as PPS (Polyphenylene sulfide) resin, UP (unsaturated polyester), PBT (polybutyleneterephtalate), and ABS; and inorganic insulating material such as ceramics depending upon the environment in which the DC circuit breaker 10 is used. The shutter 73 is formed into a plate shape as a whole and is movably stored inside the case 20, in this case, the second case 22. As shown in
The shutter 73 constantly receives elastic force from the shutter inserting spring 72. As shown in
A distal end 731 located in the direction of movement of the shutter 73 is formed in a tapered shape that becomes thinner toward the distal end side. As shown in
The moving end of the distal end 731 of the shutter 73 fits into the shutter receiver 213. Thus, the shutter 73 is prevented from bouncing back and temporarily exiting through the fixed contact 33 and the movable contact 42 even when the shutter 73 is moved at high speed.
As shown in
The second case 22 of the case 20 is provided with a shutter housing 221 and a mounting member housing 222. As shown in
As shown in
A securing ring 80 secures the cases 21 and 22 divided in two and the mounting member 71 in an assembled state. The securing ring 80 is formed into an annular shape, in this case, a cylindrical shape by a metal material such as an aluminum alloy or bronze. The first case 21, the second case 22, and the mounting member 71 are inserted to the inner side of the securing ring 80 in an assembled state. The first case 21, the second case 22, and the mounting member 71 are secured to one another by swaging the securing ring 80.
At least either of the case 20 and the mounting member 71 is provided with a swage receiving portion. In the present embodiment, the first case 21 of the case 20 is provided with a swage receiving portion 214 as shown in
The swage receiving portion 712 is formed by circularly caving the mounting member 71 towards the inner side from the outer side. The swage receiving portion 214 is formed by circularly penetrating the first case to the inner side from the outer side. The swage receiving portion 214 is provided in a position corresponding to the locking portion 512 of the latch 51. Thus, the swage receiving portion 214 serves as a window penetrating the case 20 and rendering the locking state of the locking portion 512 and the moving block 43 inside the case 20 visible from the outside of the case 20. The window 214 is covered by the securing ring 80.
Next, a description will be given on an assembly method of the DC circuit breaker 10.
When assembling the DC circuit breaker 10, the worker is to first mount the fixed electrode mechanism 30, the movable electrode mechanism 40, and the latch mechanism 50 to the first case 21. Then, the worker is to combine the first case 21, having the fixed electrode mechanism 30, the movable electrode mechanism 40, and the latch mechanism 50 mounted thereto with the second case 22. Thereafter, the worker is to mount the trigger mechanism 60 to the case 20 with the first case 21 and the second case 22 combined and insert the shutter inserting mechanism 70 into the shutter housing 221 and the mount member housing 222 of the second case 22 from the outside of the case 20.
Then, the user is to visually confirm the locking state of the locking portion 512 of the latch 51 and the locked portion 435 of the moving block 43 through the window 214 which also serves as the swage receiving portion. In case there is no problem in the locking status of locking portion 512 of the latch 51 and the locked portion 435 of the moving block 43, the securing ring 80 is fitted to the case 20, whereafter the securing ring 80 is swaged to secure the first case 21, the second case 22, and the mounting member 71 with one another. The above described procedures are carried out to complete assembly of the DC circuit breaker 10.
Next, a description will be given on the operation of the DC circuit breaker 10. The DC circuit breaker 10 is placed in non-operating state, that is, in a state in which the installation surface 90 of the host device is less than a prescribed temperature as shown in
In the present embodiment, the bypass plate 41 is receives elastic force of the pressure spring 44 and is pressed toward the fixed contact 33 side. In the groove 431 in which the bypass plate 41 is inserted, a gap is defined in the moving direction of the moving block 43 when the bypass plate 41 is inserted into the groove 431. Thus, the movement of the bypass plate 41 towards the fixed contact 33 side is not inhibited by the groove 431 of the moving block 43 and therefore it is possible to more reliably place the movable contact 42 and the fixed contact 33 provided to the bypass plate 41 in intimate contact.
When the installation surface 90 of the host device is abnormally overheated to a prescribed temperature or greater, the DC circuit breaker 10 is placed in the operating state as shown in
Thereafter, when the bypass plate 41 is moved along with the moving block 43, locking of the bypass plate 41 with the shutter 73 becomes canceled to allow the movement of the shutter 73. Then, the shutter 73 becomes inserted between the fixed contact 33 and the movable contact 42 by the operation of elastic force of the shutter inserting spring 72. The circuit is closed by the distancing of the fixed contact 33 and the movable contact 42 and the insertion of the insulating shutter 73 between the fixed contact 33 and the movable contact 42. The arc generated between the fixed contact 33 and the movable contact 42 is reliably extinguished by being sandwiched between the distal end 731 of the shutter 73 and the inner surface of the case 20 and being cutoff.
According to the embodiment described above, the DC circuit breaker 10 is provided with the case 20, two fixed contacts 33, two movable contacts 42, the bypass plate 41, the moving block 43, the separating spring 45, the thermally responsive member 61, the latch 51, the shutter 73, and the shutter inserting spring 72.
The case 20 is configured by an electrically insulative material. The fixed contact 33 is fixed within the case 20. The movable contact 42 is provided so as to correspond to each of the two fixed contacts 33. The bypass plate 41 has two movable contacts 42 fixed thereto and electrically connects the two movable contacts 42. The moving block 43 is provided with a groove 431 in which the bypass plate 41 is disposed and is provided movably within the case 20 in a direction moving away from the fixed contact 33. The movement of the moving block 43 in the direction to move away from the fixed contacts 33 causes the bypass plate 41 to move away from the fixed contact 33.
The separating spring 45 constantly exerts elastic force on the moving block 43 in a direction to move away from the moving block 43 and serves as a moving block biasing member. The thermally responsive member 61 is provided in a position opposing the installation surface 90 and deforms when the installation surface 90 becomes equal to or greater than a prescribed temperature. The latch 51 is provided with the locking portion 512. When the thermally responsive member 61 is in the pre-deformation state, that is, in the non-operating state, the locking portion 512 restricts the movement of the moving block 43 by locking the moving block 43. The latch 51 operates in response to the deformation of the thermally responsive member 61 to cause the locking portion 512 to unlock from the moving block 43 and thereby cancel the restriction of the movement of the moving block 43.
The shutter 73 is configured by an electrically insulative material and is inserted between the fixed contact 33 and the movable contact 42 when the movable contact 42 is separated from the fixed contact 33. The shutter inserting spring 72 constantly exerts elastic force on the shutter 73 in a direction to cause the shutter 73 to be inserted between the fixed contact 33 and the movable contact 42 and serves as a shutter biasing member.
According to the above described configuration, when the host device is abnormally overheated, the movable contact 42 is forcibly separated from the fixed contact 33 and the shutter 73 having electrical insulativity is inserted between the movable contact 42 and the fixed contact 33. Thus, the arc generated between the movable contact 42 and the fixed contact 33 is reliably extinguished to thereby reliably cut off current flowing between the fixed contacts 33.
It may be conceived to use parts such as a shaft to render the bypass plate 41, having movable contacts 42 fixed thereto, movably. However, parts such as a shaft requires lots of assembly work such as passing the shaft through a cylindrical hole and fixing both ends of the shaft with a fixing member or the like. In contrast, according to the present embodiment, the bypass plate 41, having movable contacts 42 fixed thereto, has a curved portion 411 curved in a U shape, and the bypass plate 41 is mounted to the moving block 43 by inserting the curved portion 411 into the U-shaped groove 431 provided to the moving block 43. Thus, there is no need to use parts such as shaft to render the bypass plate 41, having movable contacts fixed thereto, movably. Thus, by reducing the number of parts, it is possible to realize downsizing and reducing assembly work. As a result, according to the present embodiment, it is possible to reliably cut off current and achieve downsizing and productivity improvement.
The shutter inserting spring 72 is configured by a torsion spring having the support arm 722 and the operating arm 723 on the ends of the coil-shaped coil portion 721. The support arm 722 is provided on the first end of the coil portion 721 and is supported by the mounting member 71 or the case 20. The operating arm 723 is provided on the second end of the coil portion 721 and exerts elastic force on the shutter 73. The shutter inserting spring 72 is stored within the case 20 so that the pre-operation angle θ1 and the post-operation angle θ2 are both equal to or less than 30 degrees. The pre-operation angle θ1 represents the angle formed by orthogonal axis P, arranged orthogonally with the moving direction of the shutter 73, and the operating arm 723 when the shutter 73 is in the non-operating state and the post-operation angle θ2 represents the angle formed by orthogonal axis P, arranged orthogonally with the moving direction of the shutter 73, and the operating arm 723 when the shutter 73 is in the operating state.
It is thus, possible to reduce the space for mounting the shutter inserting spring 72 and thereby further reduce the size of the DC circuit breaker 10.
As shown in
The DC circuit breaker 10 is further provided with the mounting member 71 to which the shutter inserting spring 72 is mounted. Further, the case 20 is provided with the shutter housing 221 and the mounting member housing 222. The shutter housing 221 is configured so as to be capable of storing the shutter 73, inserted from outside the case 20, into the case 20. The mounting member housing 222 is configured so as to be capable of storing the shutter inserting spring 72 and the mounting member 71 attached thereto, inserted from outside the case, into the case 20.
It is thus, possible to mount the shutter inserting spring 72 and the shutter 73 from the outside of the case 20. This facilitates the mounting of the shutter inserting spring 72 and the shutter 73 and thereby further improves the productivity of the DC circuit breaker 10.
The mounting member 71 is formed of electrically insulative material such as resin and is integrally provided with the support shaft 711 supporting the coil portion 721 of the shutter inserting spring 72. It is thus, not required to assemble the support shaft 711 and thereby further improve the productivity of the DC circuit breaker 10. The material of the case is selected as appropriate depending upon the environment in which the DC circuit breaker 10 is used from materials such as PPS (Polyphenylene sulfide) resin, UP (unsaturated polyester), PBT (polybutyleneterephtalate), and ABS; and inorganic insulating material such as ceramics, for example.
Further, the DC circuit breaker 10 is provided with two pressure springs 44. The two pressure springs 44 each correspond to each of the movable contacts 42. The pressure spring 44 are provided on the bypass plate 41 so as to be located on the side opposite the fixed contacts 33 and are provided between the bypass plate 41 and the moving block 43. The two pressure springs 44 serve as the movable contact biasing member that bias each of the two movable contacts 42 provided on the bypass plate 41 in a direction to press each of the fixed contacts 33.
That is, the DC circuit breaker 10 is provided with two pressure springs 44 each corresponding to each of the two movable contacts 42. It is thus, possible to reliably place the movable contacts 42 provided on the bypass plate 41 in intimate contact with the fixed contacts 33. Hence, it is possible to prevent the movable contacts 42 from readily separating from the fixed contacts 33 by oscillation or the like occurring under normal use and as a result, reliably prevent the DC circuit breaker 10 from opening by malfunctioning of the DC circuit breaker 10 such as oscillation occurring under normal use.
The elastic force of the pressure spring 44 is set to be greater than the elastic force of the separating spring 45. Thus, at the initial stage of movement of the moving block 43, the pressure spring 44 exerts a force in a direction to cancel the rotational force of the separating spring 45. Hence, at the initial stage of movement of the moving block 43, the rotation of the moving block 43 is inhibited. As a result, the moving block 43 is prevented from being caught on the inner wall of the moving block housing 211 to thereby smoothen the movement of the moving block 43.
When the moving block 43 is locked by the locking portion 512 of the latch 51, the locking portion 512 is displaced in the direction opposite the direction of rotation of the latch 51 in the operating state with respect to the central line H extending along the moving direction of the moving block 43 and passing through the latch shaft 52 which serves as the center of rotation of the latch 51. Thus, as the force exerted on the latch 51 from the moving block 43 becomes greater, rotational force is exerted on the latch 51 in the direction opposite the direction of movement of the latch 51 indicated by the white box arrow indicated in
The case 20 is configured by combining multiple sub-cases, in this case, two sub-cases, namely, the first case 21 and the second case 22. The first case 21 and the second case 22 constituting the case 20 are secured with one another by being inserted through a securing ring 80 formed into an annular shape and swaging the securing ring 80. It is thus, possible to obviate the need for fastening members such as a bolt and a nut for assembling the first case 21 and the second case 22 and thereby reduce the number of parts while obviating the need for providing a space for providing the fastening members. Further, because the first case 21 and the second case 22 may be assembled by swaging the securing ring 80, there is no need to mount the fastening members and thereby reduce the assembly work and improve productivity.
The case 20 is provided with the window 214. The window 214 penetrates the case 20 and allows the locking portion 512 of the latch 51 provided inside the case 20 to be visible from outside the case 20. The securing ring 80 is provided in a position to cover the window 214.
Thus, the worker is allowed to check the locking state of the latch 51 and the moving block 43 through the window 214 up to the point when the securing ring 80 is mounted to complete the assembly of the DC circuit breaker 10. Thus, when the latch 51 and the moving block 43 become unlocked due to oscillation , or the like, which occurred during assembly for example, it is possible to promptly confirm that unlocking has occurred by viewing the inside of the case 20 through the window 214. It is thus, possible to reliably find a failure at the time of assembly in which the assembly is being carried out with the latch 51 and the moving block 43 unlocked, that is, assembly is carried out with the movable contact 42 and the fixed contact 33 opened and thereby prevent such defective product from being released to the market.
The securing ring 80 is provided in a position to cover the window 214. It is thus, possible to prevent the user from accidently touching the latch 51 inside the case 20 through the window 214 to cause the latch 51 to be unlocked and thereby prevent the DC circuit breaker 10 from operating unintentionally.
The case 20 is provided with the thermally responsive member mount 201. The thermally responsive member mount 201 is a portion to which the thermally responsive member 61 is mounted and is formed so as to protrude toward the installation surface 90. In the periphery of the thermally responsive member mount 201, the space 11 is defined between the case 20 and the installation surface.
Thus, it is possible to make it difficult for the case 20 to be affected by the heat coming from the installation surface 90 by the operation of the space 11. That is, because it becomes difficult for the heat from the installation surface 90 to be transferred to portions other than the thermally responsive member 61, it becomes difficult for the thermally responsive member 61 from being affected by the heat accumulated in the case 20, for example, and thereby allow the variation of heat of the installation surface 90 to be detected more accurately. That is, by delaying the heat transfer from the installation surface 90 to the case 20, it is possible to detect the variation of heat more accurately by efficiently transferring the heat of the installation surface 90 to the thermally responsive member 61 when a sudden temperature elevation occurs. Thus, it is possible for the DC circuit breaker 10 to promptly execute a cutoff operation when the temperature of the installation surface 90 is elevated to a prescribed temperature or greater.
The movable contact biasing member 44, the moving block biasing member 45, and the shutter biasing member 72 are not limited to a spring, but may be replaced by an elastic material such as rubber as long as the same functionalities can be provided.
In the present embodiment, the case 20, the mounting member 71, and the shutter 73 are configured by electrically insulative resin materials. However, the materials need not be the same, but may be a combination of different types of materials. The electrically insulative materials constituting the case 20, the mounting member 71, and the shutter 73 are selected as required from PBT, PPS (Polyphenylene sulfide) resin, UP (unsaturated polyester), and ABS; and inorganic insulating material such as ceramics, for example.
The foregoing embodiment has been presented by way of example only, and is not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiment described herein may be made without departing from the spirit of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and gist of the invention.
This is a National Stage Entry into the United States Patent and Trademark Office from International Patent Application No. PCT/JP2018/034858, filed on Sep. 20, 2018, the entire content of which is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2018/034858 | 9/20/2018 | WO | 00 |