JP7795508B2 - Microswitches and pressure-responsive switches - Google Patents

Description

The present invention relates to microswitches and pressure-activated switches.

Conventionally, microswitches equipped with manual reset mechanisms are known (see, for example, Patent Document 1). In the microswitch (thermal relay) described in Patent Document 1, as shown in FIG. 1 of Patent Document 1, a movable contact (5) is provided between a NO contact (9) and an NC contact (10) as fixed contacts, and the movable contact (5) is supported by a movable contact plate (14). The movable contact plate (14) is connected to an adjustment plate (12) via a reversing spring (13). An adjustment screw (11) is disposed near the adjustment plate (12) and can be tightened to press the adjustment plate (12) in the plate thickness direction. In this microswitch, the adjustment plate (12) is displaced by adjusting the tightening amount of the adjustment screw (11), and the resulting reversing force of the reversing spring (13) is adjusted to adjust the reset position of the movable contact plate (14).

Japanese Utility Model Application Publication No. 53-149869

In the above-mentioned microswitch, the reset position is determined by the balance between the biasing force of the adjusting plate (12) and the reversing force of the reversing spring (13). Therefore, variations in the dimensions of the adjusting plate (12) and the reversing spring (13) may cause the state of the movable contact (5) to be unstable. Furthermore, the tightening amount of the adjusting plate (12) may vary due to the influence of vibrations acting on the microswitch. This can result in unintended auto-resetting, or conversely, inability to reset, making it difficult to operate the manual reset mechanism accurately.

The objective of the present invention is to provide a manual reset microswitch and a pressure-responsive switch that are highly reliable in operation.

In order to solve the above problems and achieve the objectives, the microswitch of the present invention comprises a lever that rotates in the forward and backward directions around a rotation axis, a movable contact that performs a reversing movement as the lever rotates, a pair of fixed contacts to which the movable contact can be connected, and a regulating portion that regulates the position of the lever in the rotation direction. The rotation range of the lever includes a first reversal position where the reversal movement occurs when the lever passes in the forward direction, and a second reversal position where the reversal movement occurs when the lever passes in the backward direction. The regulating portion is displaceable between a regulating position that regulates the rotation of the lever in the backward direction between the first and second reversal positions after passing the first reversal position in the forward direction, and a reset position where the lever in the backward direction is rotated until it passes the second reversal position.

According to this invention, the position of the regulating portion can be adjusted to regulate the position of the lever in the rotational direction, and the position of the movable contact can be adjusted according to the position of the lever in the rotational direction. Therefore, the restricting position can be accurately determined according to the position of the regulating portion, and the state in which the lever's rotation in the retracting direction from the restricting position is accurately maintained, allowing for accurate control of the reversing operation of the movable contact. This differs from the conventional microswitch shown in Patent Document 1, which relies on the balance of forces to operate the reset mechanism. In other words, unlike a structure in which the state of the movable contact (5) is unstable due to dimensional variations in the adjusting plate (12) and reversing spring (13), and the tightening amount of the adjusting plate (12) varies due to influences such as vibration, this configuration accurately operates the reset mechanism by controlling the position of the regulating portion. Therefore, this configuration prevents unintended auto-resetting and ensures reliable reset operation when necessary. Therefore, a manual reset microswitch with high operational reliability can be provided.

Furthermore, it is preferable that the regulating portion includes a reset plate that regulates the position of the lever in the rotational direction, and a reset shaft that moves the reset plate back and forth in the axial direction, with the reset position being located on one side in the axial direction and the restriction position being located on the other side in the axial direction. With this configuration, the reset plate can be easily displaced between the restriction position and the reset position by moving the reset shaft back and forth in the axial direction.

It is also preferable that a biasing means is provided that biases the reset shaft toward the other axial direction, and that the regulating portion can be displaced to the reset position by pressing the reset shaft toward one axial direction against the biasing force of the biasing means, and that the regulating portion is located at the restricted position when the reset shaft is not pressed. With this configuration, pressing the reset shaft toward one axial direction displaces the reset plate to the reset position, and by ceasing to press the reset shaft, the biasing force of the biasing means automatically displaces the reset plate to the restricted position, and it can be located at the restricted position.

The pressure responsive switch of the present invention is characterized by incorporating any of the microswitches described above. This configuration allows the pressure responsive switch to be constructed using a manual reset microswitch with highly reliable operation.

The present invention provides a manual reset microswitch with highly reliable operation.

FIG. 2 is a bottom view of a pressure responsive switch equipped with a microswitch according to an embodiment of the present invention. FIG. FIG. 3 is a cross-sectional view of the microswitch taken along line AA in FIG. 2 when the manual reset mechanism is released. 3 is a cross-sectional view of the microswitch showing the release waiting state of the manual reset mechanism taken along line AA in FIG. 2; Bottom view of the microswitch. 5A and 5B are schematic diagrams showing the operation of a microswitch equipped with an auto-reset mechanism. 10A and 10B are schematic diagrams showing the operation of a microswitch equipped with a manual reset mechanism up to the time when pressure is decreasing. 10A and 10B are schematic diagrams showing the operation of a microswitch equipped with a manual reset mechanism during and after a pressure drop; 5A and 5B are schematic diagrams showing the adjustment operation of the manual reset mechanism.

One embodiment of the present invention will now be described. The microswitch 1 according to this embodiment is mounted in a pressure-responsive switch 100 or the like that detects changes in fluid pressure or temperature. For example, the microswitch 1 detects changes in the pressure or temperature of a working medium, such as a refrigeration cycle, an automobile, or an actuator for various controls. In the following description, the axial direction of the operating shaft 20 and reset shaft 71 (described below) is indicated by arrow Z in the drawings and referred to as the "vertical direction Z." One side of the vertical direction Z is referred to as the "upper side Z1," and the other side is referred to as the "lower side Z2." Horizontal directions intersecting the vertical direction Z are indicated by arrows X and Y and referred to as the "front-rear direction X" and the "left-right direction Y," respectively. One side of the front-rear direction X is referred to as the "front side X1," the other side as the "rear side X2," and one side of the left-right direction Y is referred to as the "left side Y1," and the other side as the "right side Y2." These directional definitions are for the convenience of explanation only, and do not necessarily correspond to the directions in the actual state of use of the microswitch 1, and do not limit the directions in the actual state of use of the microswitch 1.

As shown in FIG. 1, the pressure-responsive switch 100 includes a generally rectangular case 110. The case 110 includes a C-shaped main frame 111 that opens to the lower side Z2 and a cover (not shown) that closes the opening of the main frame 111. The case 110 houses various components, such as the microswitch 1 (described below). The main frame 111 is formed by bending a metal plate and includes a front wall 112, a top wall 113, and a rear wall 114. A pair of elements 115 and a pair of coupling tubes 116, each connected to the pair of elements 115, are connected to the rear wall 114 of the case 110. The elements 115 include a sensitive member such as a bellows or diaphragm (not shown) inside. The sensitive member deforms or displaces in the forward/backward direction X in response to pressure changes in the pressurized fluid introduced through the coupling tube 116.

The case 110 houses a pair of left and right transmission mechanisms 117 and a pair of left and right switch components 118. The transmission mechanism 117 includes a reinforcing plate 119 formed by bending a metal plate into a C-shape with an opening on the upper side Z1. The reinforcing plate 119 houses a transmission member 120. An example of the transmission member 120 is an actuating plate 121. The actuating plate 121 receives an external force, such as a force that deforms or displaces the above-mentioned sensitive member, and rotates around a rotation axis 122 to convert the external force into an operating force, which is then transmitted to the pressure arm 17 and lever 16 (reaction member) described below. The switch component 118 includes multiple contacts 40 (described below) and changes the electrical conduction state of the contacts 40 upon receiving the above-mentioned operating force. A pair of switch components 118 are provided adjacent to each other in the left-right direction Y, forming a dual-type microswitch 1. The microswitch 1 is configured with a manual reset mechanism 2, which will be described later, and by operating the reset button 76 on the manual reset mechanism 2, the contacts 40, which are in a predetermined conductive state, can be manually switched to a different conductive state.

Figure 2 is a perspective view of the microswitch 1, and Figure 3 is a plan view of the microswitch 1. Note that Figure 2 omits the reset shaft 71 and reset plate 72, which are described below and which constitute the manual reset mechanism 2 described below. The microswitch 1 includes a box portion 10. The box portion 10 is formed, for example, from a resin material in a generally cubic shape, and its interior defines an accommodation space 11 for accommodating various components. A connecting portion 13 that protrudes toward the rear side X2 is formed on the rear wall 12 of the box portion 10. The connecting portion 13 is formed in a plate shape extending in the vertical direction Z and is fixed to the case 110 of the pressure-responsive switch 100 described above. A rectangular box-shaped fixing member 14 is attached to the top wall of the box portion 10. In this embodiment, a pair of fixing members 14 are attached side by side in the horizontal direction Y. A rotation shaft 15 extending in the left-right direction Y is fixed to the side wall of each fixed member 14, and a lever 16 is attached to the rotation shaft 15 so that it can rotate around the shaft. In other words, a pair of levers 16 is provided. In this embodiment, "rotation" means rotating forward and backward around the rotation shaft 15 within a specified angular range.

The lever 16 is a metal plate-shaped operating fixture that extends from the pivot shaft 15 toward the front side X1 and is rotatable in a forward direction a and a backward direction b around the pivot shaft 15. In the initial state shown in FIG. 2, the lever 16 is biased in the backward direction b by a biasing means (not shown) and is tilted toward the upper side Z1 as it extends from the rear end supported by the pivot shaft 15 toward the front end. The lever 16 rotates in the forward direction a around the pivot shaft 15 when subjected to an external force. An example of such an external force is a force generated in response to changes in refrigerant pressure in the refrigeration cycle described above. Such a force is applied to a sensitive member (not shown) mounted on the pressure switch and transmitted to the lever 16 via the pressure arm 17 shown in FIG. 3. The pressure arm 17 is formed into a roughly L-shaped shape in plan view by bending a metal plate.

The tip of the pressure arm 17 is positioned above the lever 16 on the upper side Z1, except for the portion of the front end of the lever 16 on the inner side in the left-right direction Y. It is displaced below the Z2 in response to the force applied to the sensor, causing the lever 16 to rotate in the forward direction a around the pivot shaft 15. A receiving portion 18 is formed on the plate surface of the lever 16. As shown in Figure 4, the receiving portion 18 is formed by protruding the middle portion of the plate surface of the lever 16 in the front-to-rear direction X toward the upper side Z1, and has a V-shaped cross-section that opens to the lower side Z2. The receiving portion 18 supports an operating shaft 20 whose axis extends in the vertical direction Z. The operating shaft 20 is a shaft member that converts the pivotal movement of the lever 16 into forward and backward movement in the vertical direction Z.

The operating shaft 20 is inserted into a through-hole 19 that penetrates the top wall of the box portion 10 in the vertical direction Z and is connected to the box portion 10 so as to be movable back and forth in the vertical direction Z. The upper end of the operating shaft 20 forms a pressed portion 21 that is pressed by the lever 16. In this embodiment, the pressed portion 21 slides against the V-shaped inner surface of the receiving portion 18 of the lever 16 and is pressed downward Z2. Meanwhile, the lower end of the operating shaft 20 forms an engaging portion 22 that engages with the switching means 30, which will be described later. The switching means 30 is configured to switch the conductive state of a contact 40 located within the storage space 11 and includes a movable piece 31 that engages with the engaging portion 22 of the operating shaft 20, a snap piece 32 that abuts against the front end of the movable piece 31, and a conductive piece 33 that has a movable contact 42, which will be described later, that is biased upward Z1 or downward Z2 by the snap piece 32.

The snap piece 32 biases the movable contact 42 toward the upper side Z1 or the lower side Z2 depending on the position of the engagement portion 22 on the operating shaft 20. Specifically, in the initial state described above, in which the pressure arm 17 is not pressing the lever 16, the snap piece 32 biases the movable contact 42 toward the lower side Z2. Then, as the pressure arm 17 presses the lever 16, the operating shaft 20 descends, and the engagement portion 22 moves toward the lower side Z2, the snap piece 32 gradually deforms while maintaining its biasing direction toward the lower side Z2. Then, when the engagement portion 22 of the operating shaft 20 moves toward the lower side Z2 beyond the lower limit position (not shown), the snap piece 32 can no longer maintain its biasing direction toward the lower side Z2 and reverses to the upper side Z1, biasing the movable contact 42 toward the upper side Z1 as shown in FIG. 5. From this state, the engaging portion 22 of the operating shaft 20 rises, and as the engaging portion 22 moves toward the upper side Z1, the snap piece 32 gradually deforms while maintaining its biasing direction toward the upper side Z1. When the engaging portion 22 of the operating shaft 20 moves toward the upper side Z1 beyond the upper limit position (not shown) (a position Z1 above the lower limit position described above), the snap piece 32 can no longer maintain its biasing direction toward the upper side Z1 and reverses to the lower side Z2, biasing the movable contact 42 toward the lower side Z2 as shown in FIG. 4.

The contacts 40 are conductive members made of a conductive material and include a pair of fixed contacts 41 fixed within the storage space 11 and a movable contact 42 located between the pair of fixed contacts 41. The pair of fixed contacts 41 consists of a first fixed contact 41A and a second fixed contact 41B. The first fixed contact 41A is fixed to the inner wall of the box portion 10 facing the upper side Z1. The second fixed contact 41B is fixed to the inner wall of the box portion 10 facing the lower side Z2 and above the first fixed contact 41A. The movable contact 42 is fixed to the front end of the conductive piece 33 and can abut against the first fixed contact 41A or the second fixed contact 41B by displacing upward Z1 or downward Z2, which is the biasing direction of the snap piece 32, thereby establishing electrical contact with the first fixed contact 41A or the second fixed contact 41B.

As described above, the movable contact 42 can be reversed to switch its electrical connection by changing the direction of its bias when the snap piece 32 is reversed in the vertical direction Z. Specifically, the movable contact 42 can be switched between a first electrical connection state ("Operation-Fixed A: ON" in the tables of Figures 7-9) in which it is displaced downward Z2 and is electrically connected to the first fixed contact 41A, and a second electrical connection state ("Operation-Fixed A: OFF" in the tables of Figures 7-9) in which it is displaced upward Z1 and is electrically connected to the second fixed contact 41B. Note that in the following description, the "first electrical connection state" may be referred to as the first electrical connection state (operation-fixed A: ON), and the "second electrical connection state" may be referred to as the second electrical connection state (operation-fixed A: OFF).

In this embodiment, in the initial state described above, in which the pressing arm 17 is not pressing the lever 16, the snap piece 32 biases the movable contact 42 downward Z2, thereby placing the movable contact 42 in the first conductive state. A terminal 50 is connected to the contact 40 configured in this manner. The terminal 50 is a member to which the first fixed contact 41A, second fixed contact 41B, and movable contact 42 are connected in a one-to-one relationship, and is formed in a plate shape using a conductive material. In this embodiment, a pair of levers 16 is provided on the box portion 10, and therefore a pair of operating shafts 20, switching means 30, and contacts 40 corresponding to each lever 16 is also provided. This results in a total of six contacts 40. Therefore, as shown in FIG. 6, a total of six terminals 50 are provided. The terminal 50 is inserted into an insertion hole 10a formed in the bottom wall of the box portion 10, and the attachment portion 51 at the bottom end to which an electric wire (not shown) is connected is bent using a fastening member 123 (see Figure 1), and the attachment portion 51 is fixed along the bottom wall of the box portion 10.

In this embodiment, the microswitch 1 has a snap piece 32. Therefore, in cases where the microswitch does not have a mechanism related to the manual reset mechanism 2 (described below), i.e., a so-called auto-reset type microswitch, the microswitch operates as follows when the lever 16 rotates. Specifically, as shown by "Initial (0 MPa)" in the table in Figure 7, the lever 16, which is in its initial state, rotates in the direction of travel a due to an increase in fluid pressure, as shown by "Pressure Rising" in the table in Figure 7. As a result, the operating shaft 20 descends. When the engaging portion 22 moves downward Z2 beyond the aforementioned lower limit position where the snap piece 32 can no longer maintain its biasing direction toward the lower side Z2, the snap piece 32 reverses, causing the movable contact 42 to reverse, switching the conduction state from the first conduction state (operation-fixed A: ON) to the second conduction state (operation-fixed A: OFF). The state of the lever 16 when this reversal occurs is shown by "Above Rising Actuation Value" in the table in Figure 7. The auto-reset type microswitch described above is sometimes called an automatic return type microswitch.

In this embodiment, the position where the reversal occurs when the lever 16 passes in the direction of travel a is the first reversal position (referred to as the rising point in Figures 7-9) in the rotational direction of the lever 16. With this configuration, for example, by incorporating the microswitch 1 in a pressure switch, a high-pressure cutoff switch can be configured that switches the conduction state from the first conduction state to the second conduction state when abnormally high pressure occurs. In the case of an auto-reset (or automatic return) microswitch as described above, as shown in "During Pressure Decrease" in the table of Figure 7, after the reversal (i.e., after cutoff), the lever 16 rotates in the retraction direction b due to a decrease in fluid pressure, causing the operating shaft 20 to rise and return to the first conduction state before the switch ("initial (0 MPa)" shown in Figure 7), if the engaging portion 22 moves to the upper side Z1 beyond the upper limit position where the snap piece 32 can no longer maintain its biasing direction on the upper side Z1, the snap piece 32 reverses, causing the movable contact 42 to reverse. This switches the conduction state from the second conduction state to the first conduction state.

In this embodiment, the position where a reversal occurs when the lever 16 passes in the reverse direction b is the second reversal position (referred to as the "downward point" in Figures 7-9) in the rotation direction of the lever 16. With this configuration, the rotation range of the lever 16 includes the first reversal position (upward point) where a reversal occurs when the lever 16 passes in the forward direction a, and the second reversal position (downward point) where a reversal occurs when the lever 16 passes in the reverse direction b. In this way, the microswitch 1 of this embodiment is configured as a switch in which the first reversal position, which is a set value that triggers high-pressure cutoff, and the second reversal position, which is a set value that triggers a return to the original state, are different positions. Note that in the following description, the "first reversal position" may be referred to as the first reversal position (upward point), and the "second reversal position" may be referred to as the second reversal position (downward point).

The microswitch 1 configured in this manner includes a manual reset mechanism 2. For example, when the above-mentioned high-voltage cutoff occurs, the manual reset mechanism 2 maintains the second conductive state for the purpose of subsequent maintenance work by an operator, and after the maintenance work is completed, the manual reset mechanism 2 releases the second conductive state and returns to the first conductive state. As shown in FIG. 4 , the manual reset mechanism 2 includes a mounting hole 60 formed through the box portion 10. The mounting hole 60 includes a shaft support portion 61 extending in the vertical direction Z and opening into the top wall of the box portion 10, a spring bearing portion 62 continuing from the lower end of the shaft support portion 61 and having a larger inner diameter than the shaft support portion 61, extending downward Z2, and a button support portion 63 continuing from the lower end of the spring bearing portion 62, having a larger inner diameter than the spring bearing portion 62, and opening into the bottom wall of the box portion 10.

A reset member 70 (regulating portion) that determines the rotational position of the lever 16 is inserted into the mounting hole 60. The reset member 70 includes a cylindrical reset shaft 71 extending in the vertical direction Z. A threaded portion (not shown) is formed on the upper end of the reset shaft 71, and a reset plate 72 that protrudes toward the rear side X2 is threadedly engaged with this threaded portion. As shown in FIG. 3 , the reset plate 72 includes a substantially rectangular plate-shaped main body 72a with its four corners cut out, and a pressing portion 72b that protrudes outward in the horizontal direction Y from the outer edge of the main body 72a in the horizontal direction Y. The lower surface of the pressing portion 72b is configured to press against the upper surface of the inner portion of the front end of the lever 16 in the horizontal direction Y. When the reset plate 72 displaces in the vertical direction Z in accordance with the displacement of the reset shaft 71 in the vertical direction Z, it presses the lever 16 downward Z2, thereby determining the rotational position of the lever 16. That is, the reset shaft 71 moves the reset plate 72 back and forth in the vertical direction Z, and this movement determines the position of the reset plate 72 in the rotation direction of the lever 16.

The reset plate 72 can be displaced in the vertical direction Z relative to the reset shaft 71 by screwing in the threaded engagement portion. A first E-ring 73 is attached to the lower side Z2 of the reset plate 72 (between the reset plate 72 and the opening of the mounting hole 60 on the reset plate 72 side). The first E-ring 73 protrudes radially outward from the reset shaft 71, and its lower surface can abut against the upper wall of the box portion 10. This prevents the reset shaft 71 from displacing downward Z2 from the position where the lower surface of the first E-ring 73 abuts against the upper wall of the box portion 10, as shown in FIG. 5 . In other words, the first E-ring 73 defines the lower end position L of the reset shaft 71. A second E-ring 74 is attached to the lower end of the reset shaft 71. The second E-ring 74 protrudes radially outward from the reset shaft 71, and its upper surface can abut against the step at the boundary between the spring receiving portion 62 and the button support portion 63. As a result, as shown in FIG. 4, the reset shaft 71 is restricted from displacing upward Z1 from the position where the upper surface of the second E-ring 74 abuts against the step at the boundary between the spring receiving portion 62 and the button support portion 63. In other words, the second E-ring 74 defines the upper end position H of the reset shaft 71.

A reset spring 75 (biasing means) is housed between the second E-ring 74 and the upper end of the spring bearing portion 62. In other words, the second E-ring 74 also functions as a spring bearing. The reset spring 75 biases the reset shaft 71 downward Z2 via the second E-ring 74. A reset button 76 is attached to the lower end of the reset shaft 71. The reset button 76 is an operation device used by an operator to displace the reset shaft 71 in the vertical direction Z, and is elliptical in bottom view as shown in Figure 6. The reset button 76 is supported by the button support portion 63 and can be pushed upward Z1 up to the step at the boundary between the button support portion 63 and the spring bearing portion 62. By pushing the reset button 76, the reset shaft 71 is displaced upward Z1 against the biasing force of the reset spring 75. The biasing force of the reset spring 75 and the amount of depression of the reset button 76 can be adjusted as needed, but in this embodiment, when the reset button 76 is pressed to its limit, the reset shaft 71 is displaced to its upper end position H. On the other hand, when the reset button 76 is not pressed, the biasing force of the reset spring 75 automatically positions the reset shaft 71 at its lower end position L.

Next, the operation of the microswitch 1 will be described. Figure 8 is a schematic diagram showing the operation of the microswitch 1 equipped with the manual reset mechanism 2 up until the pressure is decreasing. Figure 9 is a schematic diagram showing the operation of the microswitch 1 equipped with the manual reset mechanism 2 after the "pressure is decreasing" stage. Note that in Figures 8 and 9 (Figure 10), the pivot shaft 15, lever 16, and reset plate 72 are shown in schematic rather than actual shapes to avoid cluttering the illustrations. First, when the reset button 76 is not operated, as shown by "Initial (0 MPa)" in the table in Figure 8, the lever 16 is positioned between the first and second reversal positions while abutting against the reset plate 72. In this state, the movable contact 42 is conductive with the first fixed contact 41A, establishing the first conductive state (operated-fixed A: ON).

From this state, as shown by "Pressure Rising" in the table of FIG. 8, the fluid pressure rises. If the fluid pressure continues to rise from this state and reaches an abnormally high pressure that exceeds expectations, the lever 16 will be displaced in the forward direction a and exceed the first reversal position (rising point), as shown by "Above Rising Activation Value" in the table of FIG. 8. This causes the movable contact 42 to reverse, displacing the movable contact 42 to the upper side Z1 and conducting with the second fixed contact 41B, switching to the second conducting state (operating-fixed A: OFF). Then, if the fluid pressure drops from this state, as shown by "Pressure Decreasing" in the table of FIG. 8, the lever 16 will rotate in the backward direction b. This rotation is then restricted by the lever 16 abutting against the reset plate 72, as shown by "Below Decreasing Activation Value = Waiting to Release" in the table of FIG. 9.

The position where the rotation of the lever 16, which passes through the first reversal position (upward point) in the forward direction a and then moves in the backward direction b, is restricted between the first reversal position (upward point) and the second reversal position (downward point) is defined as the "restriction position P1." In this embodiment, as shown in FIG. 5, the position where the reset plate 72 and the lever 16 abut when the reset shaft 71 is located at the lower end position L is the restriction position P1. As described above, the microswitch 1 of the present invention is configured as a switch in which the first reversal position (upward point), which is the set value used as a trigger to execute high-pressure cutoff, and the second reversal position (downward point), which is the set value used as a trigger to return to the original state, are different positions. Therefore, when the rotation of the lever 16 in the backward direction b is restricted at the restriction position P1, the position of the lever 16 in the rotation direction is between the first reversal position (rising point) and the second reversal position (falling point), just like the rotation direction position shown at "initial 0 MPa" in the table in Figure 8, but no reversal operation of the movable contact 42 occurs, and the second conduction state is maintained.

For example, if an alarm is sounded in the second conduction state, an operator can be notified of an abnormality even if the abnormality is automatically corrected. This allows the operator to perform maintenance, which is useful. After completing maintenance, to reset the movable contact 42 by returning it from the second conduction state to the first conduction state, the lever 16 must be rotated in the backward direction b and the reset plate 72 must be displaced to a position where it can pass through the second reversal position (downward point). As shown in Figure 4, the reset button 76 is pushed upward Z1, displacing the reset shaft 71 and reset plate 72 upward Z1. This allows the lever 16 to rotate in the backward direction b and pass through the second reversal position, as shown in the "Released (Button Pressed)" column in the table in Figure 9. At this time, a reversal operation occurs, and the movable contact 42 switches from the second conductive state (operating-fixed A: OFF) to the first conductive state (operating-fixed A: ON).

The position at which the lever 16, moving in the backward direction b, is rotated until it passes through the second reversal position (downward point) is defined as the "reset position P2." In this embodiment, as shown in FIG. 4 , the reset position P2 is the contact position between the reset plate 72 and the lever 16 when the reset shaft 71 is at the upper end position H. With this configuration, in the vertical direction Z of the reset shaft 71, the reset position P2 is located on the upper side Z1 (one axial side), and the restriction position P1 is located on the lower side Z2 (the other axial side). The reset plate 72 (reset member 70) is supported so that it can be displaced between the reset position P2 and the restriction position P1. Finally, when the reset button 76 is released, the biasing force of the reset spring 75 automatically displaces the reset shaft 71 to the lower side Z2, returning the reset plate 72 to its original position (restriction position P1), completing the operation of the manual reset mechanism 2.

As described above, in this embodiment, the contact position between the reset plate 72 and the lever 16 when the reset shaft 71 is located at the lower end position L is the restriction position P1, and the contact position between the reset plate 72 and the lever 16 when the reset shaft 71 is located at the upper end position H is the reset position P2. However, this is merely an example, and any position that meets the definition of the restriction position P1 and can be moved to the reset position P2 may be used as the restriction position P1. Furthermore, any position that meets the definition of the reset position P2 and can be moved to the restriction position P1 may be used as the reset position P2. Next, the adjustment operation of the manual reset mechanism 2 will be described. Figure 10 is a schematic diagram showing the adjustment operation of the manual reset mechanism 2. As described above, in the microswitch 1 of this embodiment, when the movable contact 42 changes from the first conductive state to the second conductive state, the second conductive state is maintained. This is particularly important when the microswitch 1 detects an abnormality and changes from the first conduction state to the second conduction state, in order to notify an operator of the abnormality. In other words, it is necessary for the switch to change from the second conduction state to the first conduction state only when the reset button 76 is pressed. Therefore, when the reset button 76 is not operated, the lever 16 must be accurately positioned at the restricting position P1 and maintained in that state, and when the reset button 76 is operated, the lever 16 moving in the backward direction b must reliably pass through the reset position P2; for this reason, the first reversal position (ascending point) and the second reversal position (descending point) must be accurately determined.

Then, adjust the manual reset mechanism 2. First, as shown in the "Initial" and "Forced Operation" columns in the table of Figure 10, the lever 16, which is in its initial state, is forcibly rotated in the forward direction a by the reset plate 72 until it is positioned at the position where it changes from the first conductive state to the second conductive state, i.e., the first reversal position (ascending point). As mentioned above, it is useful to use a screw to move the reset plate 72 downward Z2 relative to the reset shaft 71, as this allows for fine adjustment of the position of the reset plate 72. Next, as shown in the "Looking for the descending point" column in the table of Figure 10, the lever 16 is rotated in the backward direction b by the reset plate 72 until it is positioned at the position where it changes from the second conductive state to the first conductive state, i.e., the second reversal position (ascending point).

At this time, it is useful to use a screw to move the reset plate 72 upward Z1 relative to the reset shaft 71, allowing for fine adjustment of the position of the reset plate 72. These operations accurately determine the first reversal position (ascending point) and the second reversal position (descending point). This allows the reset position P2 to be accurately determined and the restriction position P1 to be accurately determined. Finally, as shown under "Adjustment" in the table in Figure 10, the lever 16 is rotated in the direction of travel a by the reset plate 72, positioning the lever 16 between the first reversal position (ascending point) and the second reversal position (descending point), which is set to the restriction position P1. This completes the adjustment of the manual reset mechanism 2.

Note that it is also possible to reverse the adjustment operation described above by positioning the lever 16 at the second reversal position (descent point), then at the first reversal position (ascension point), and then making the final adjustment described above toward the second reversal position (descent point) to define the restriction position P1. However, according to this embodiment, by making the final adjustment from the second reversal position (descent point) toward the first reversal position (ascension point), it is possible to reliably position the lever 16 closer to the first reversal position (ascension point) than the second reversal position (descent point), thereby more reliably preventing unintended auto-reset.

As described above, according to the embodiment, the rotational position of the lever 16 can be determined by displacing the position of the reset member 70 (determining portion), and the position of the movable contact 42 can be determined according to the rotational position of the lever 16. Therefore, the restriction position P1 can be accurately determined according to the position of the reset member 70, and the state in which the rotation of the lever 16 in the retraction direction b from the restriction position P1 can be accurately maintained, thereby accurately managing the reversal operation of the movable contact 42. This differs from the conventional microswitch structure shown in Patent Document 1, which relies on the balance of forces to operate the reset mechanism. That is, unlike the structure in which the state of the movable contact (5) is unstable due to dimensional variations in the adjustment plate (12) and reversal spring (13), and the tightening amount of the adjustment plate (12) varies due to influences such as vibration, this configuration accurately operates the manual reset mechanism 2 (reset mechanism) by managing the position of the reset member 70. Therefore, this configuration prevents unintended auto-reset and reliably performs reset operation when necessary. Therefore, a microswitch 1 (manual reset type microswitch) with high operational reliability can be provided.

Furthermore, according to this embodiment, the reset member 70 includes a reset shaft 71 and a reset plate 72. Therefore, by moving the reset shaft 71 back and forth in the vertical direction Z (axial direction), the reset plate 72 can be easily displaced between the restricting position P1 and the reset position P2.

Furthermore, according to this embodiment, by pressing the reset shaft 71 upward Z1, the reset plate 72 is displaced to the reset position P2, and by ceasing to press the reset shaft 71, the biasing force of the reset spring 75 (biasing means) automatically displaces the reset plate 72 to the restriction position P1, allowing it to be positioned at the restriction position P1.

Furthermore, according to this embodiment, the pressure-responsive switch 100 can be constructed using a microswitch 1 (manual reset type microswitch) with highly reliable operation.

The above-described embodiments merely illustrate typical aspects of the present invention, and the present invention is not limited to these. In other words, various modifications can be made without departing from the gist of the present invention. Such modifications, as long as they incorporate the configuration of the microswitch 1 of the present invention, are naturally within the scope of the present invention. For example, in the description of this embodiment, the microswitch 1 and manual reset mechanism 2 are described as being used to detect abnormally high pressure. However, conversely, the microswitch 1 and manual reset mechanism 2 can also be used to detect abnormally low pressure. Furthermore, in the initial state, the lever 16 is inclined so that it is positioned on the upper side Z1 as it moves from the rear end supported by the pivot shaft 15 toward the front end. However, the microswitch 1 and manual reset mechanism 2 may be configured in the opposite way by setting the state after rotation in this embodiment as the initial state of the lever 16, setting the retraction direction b in this embodiment as the forward direction a, and adjusting the operating direction of the actuating shaft 20, switching means 30, and manual reset mechanism 2 accordingly.

Furthermore, the microswitch 1 and manual reset mechanism 2 can be mounted on various switches other than pressure switches in which the lever 16 rotates in response to some external force. For example, while the pressure-responsive switch 100 of this embodiment has been described primarily as a pressure switch, it can also be used as a temperature switch. In other words, this embodiment describes its use as a pressure switch in which the fluid to be detected (here, the refrigerant circulating in the refrigeration cycle) is introduced through the coupling tube 116 and the pressure of the fluid to be detected is applied directly to a sensitive element such as a bellows or diaphragm to detect pressure changes. However, the use of the pressure-responsive switch 100 is not limited to this. A temperature switch can be constructed by connecting a temperature sensing bulb to the element 115 of the pressure-responsive switch 100 of this embodiment via a capillary and filling the closed space formed by the sensitive element, capillary, and temperature sensing bulb with refrigerant. In this way, in a temperature switch using the pressure responsive switch 100 of this embodiment, the sensitive member deforms or displaces in the vertical direction Z in response to the pressure inside the closed space, which changes in response to changes in temperature detected by the temperature sensing bulb, and this force is transmitted to the lever 16 (responsive member), changing the electrical contact state.

In this embodiment, the microswitch 1 is equipped with a pair of levers 16 and the corresponding actuation shaft 20, switching means 30, contacts 40, and terminals 50, constituting a so-called dual-type microswitch. However, the present invention is not limited to dual-type microswitches and can be applied to a variety of microswitches. In this embodiment, when the reset button 76 in the manual reset mechanism 2 is not pressed, the reset shaft 71 is automatically displaced to its pre-pressed position by the biasing force of the reset spring 75. However, this is not limited to this. The reset button 76 may be omitted and the reset shaft 71 may be manually operated to displace the reset shaft 71 to its pre-pressed position. By keeping the reset button 76 pressed, the microswitch 1 can be used like the auto-reset (automatic return) microswitch described above. Furthermore, by removing the reset member 70, such as the reset shaft 71 and reset plate 72, from the microswitch 1, the microswitch 1 can also be used as the auto-reset microswitch described above.

a Forward direction b Reverse direction P1 Restricted position P2 Reset position 1 Microswitch 15 Rotating shaft 16 Lever 41 Fixed contact 42 Movable contact 70 Reset member (regulating portion)

Claims (4)

A microswitch comprising: a lever that rotates in a forward direction and a backward direction around a rotation axis; a movable contact that performs a reversing operation in association with the rotation of the lever; a pair of fixed contacts that can be electrically connected to the movable contact; and a determining portion that determines the position of the lever in the rotation direction,
a rotation range of the lever includes a first reversal position where the reversal action occurs when the lever passes in the forward direction, and a second reversal position where the reversal action occurs when the lever passes in the backward direction,
the regulating portion is provided so as to be displaceable between a regulating position where the lever restricts rotation of the lever toward the retraction direction after passing the first reversal position in the forward direction between the first reversal position and the second reversal position, and a reset position where the lever toward the retraction direction is rotated until it passes the second reversal position. the determining portion includes a reset plate that determines the position of the lever in the rotation direction, and a reset shaft that moves the reset plate back and forth in an axial direction,
2. The microswitch according to claim 1, wherein the reset position is located on one side in the axial direction, and the restricting position is located on the other side in the axial direction. a biasing means for biasing the reset shaft toward the other axial direction,
The defining portion can be displaced to the reset position by pushing the reset shaft toward one axial direction against the biasing force of the biasing means,
3. The microswitch according to claim 2, wherein the regulating portion is located at the regulating position when the reset shaft is not pressed. A pressure-responsive switch equipped with the microswitch described in any one of claims 1 to 3.