Microswitches and pressure-responsive switches

Abstract

To provide a manually reset microswitch and a pressure-activated switch that operate reliably.SOLUTION: A microswitch 1 includes a lever 16 that rotates around a rotation shaft 15 in a forward direction a and a backward direction b, a movable contact 42 that performs a reversing operation in association with the rotation of the lever 16, a fixed contact 41, and a reset member 70. The range of rotation of the lever 16 includes a first reversal position where a reversing operation occurs when the lever 16 passes in the forward direction a, and a second reversal position where a reversing operation occurs when the lever 16 passes in the backward direction b. The reset member 70 is displaceable between a restricting position P1 that restricts the rotation of the lever 16 toward the backward direction b after passing the first reversal position in the forward direction a between the first reversal position and the second reversal position, and a reset position P2 that rotates the lever 16 toward the backward direction b until it passes the second reversal position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a microswitch and a pressure-responsive switch. [Background technology]

[0002] Conventionally, microswitches equipped with a manual reset mechanism have been 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 an 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 press the adjustment plate (12 in the plate thickness direction when tightened. In this microswitch, the adjustment plate (12) is displaced by adjusting the amount of tightening 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). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 53-149869 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described 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 be affected by 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.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a manually reset microswitch and a pressure responsive switch that are highly reliable in operation. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the microswitch of the present invention is a microswitch comprising a lever that rotates in a forward and backward direction around a rotation axis, a movable contact that performs a reversing operation as the lever rotates, a pair of fixed contacts to which the movable contact can be connected, and a regulating portion that determines the position of the lever in the rotation direction, wherein the rotation range of the lever includes a first reversal position where the reversal operation occurs when the lever passes in the forward direction, and a second reversal position where the reversal operation occurs when the lever passes in the backward direction, and the regulating portion is displaceable between a regulating position that regulates the rotation of the lever toward the backward 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 backward direction is rotated until it passes the second reversal position.

[0007] According to the present invention, the position of the determining portion can be determined to determine the position of the lever in the rotational direction, and the position of the movable contact can be determined 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 determining portion, and the state in which the lever's rotation in the retracting direction from the restricting position can be accurately maintained, thereby accurately controlling 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. That is, unlike the conventional microswitch shown in Patent Document 1, 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 determining portion. Therefore, this configuration prevents unintended auto-resetting and reliably performs resetting when necessary. Therefore, a manual reset microswitch with high operational reliability can be provided.

[0008] Preferably, the defining portion includes a reset plate that defines the position of the lever in the rotation direction and a reset shaft that moves the reset plate back and forth in the axial direction, the reset position being located on one side in the axial direction and the restricting position being located on the other side in the axial direction. With this configuration, the reset plate can be easily displaced between the restricting position and the reset position by moving the reset shaft back and forth in the axial direction.

[0009] It is also preferable that a biasing means be provided for biasing the reset shaft toward the other axial direction, and that the defining portion be displaceable to the reset position by pressing the reset shaft toward one axial direction against the biasing force of the biasing means, and that the defining portion be located at the restricted position when the reset shaft is not pressed in. With this configuration, by pressing the reset shaft toward one axial direction, the reset plate is displaced to the reset position, and by ceasing to press the reset shaft, the reset plate is automatically displaced to the restricted position by the biasing force of the biasing means, and is located at the restricted position.

[0010] Furthermore, the pressure responsive switch of the present invention is characterized by being equipped with any of the microswitches described above. With this configuration, the pressure responsive switch can be configured using a manual reset type microswitch with high operational reliability. [Effects of the Invention]

[0011] According to the present invention, a manual reset type microswitch with high operational reliability can be provided. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a bottom view of a pressure responsive switch equipped with a microswitch according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] 3 is a cross-sectional view of the microswitch taken along line AA in FIG. 2 when the manual reset mechanism is released. [Figure 5] 3 is a cross-sectional view of the microswitch showing the manual reset mechanism in a release waiting state, taken along line AA in FIG. 2. [Figure 6] Bottom view of the microswitch. [Figure 7] 5A and 5B are schematic diagrams showing the operation of a microswitch equipped with an auto-reset mechanism. [Figure 8] 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. [Figure 9] 10A and 10B are schematic diagrams showing the operation of a microswitch equipped with a manual reset mechanism during and after a pressure drop; [Figure 10] 5A and 5B are schematic diagrams showing the adjustment operation of the manual reset mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described below. The microswitch 1 according to this embodiment is mounted in a pressure-responsive switch 100 or the like that detects pressure changes or temperature changes of a fluid, for example, a working medium used in a refrigeration cycle, an automobile, or an actuator for various controls. The microswitch 1 detects pressure changes or temperature changes of the fluid. In the following description, the axial direction of an operating shaft 20 and a reset shaft 71 (described later) 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 provided merely for the convenience of explanation and do not necessarily correspond to the directions in the actual use state of the microswitch 1, and do not limit the directions in the actual use state of the microswitch 1.

[0014] As shown in FIG. 1 , the pressure-responsive switch 100 includes a generally rectangular case 110. The case 110 includes a C-shaped main body frame 111 that opens to a lower side Z2 and a cover (not shown) that closes the opening of the main body frame 111. The case 110 houses various components, such as a microswitch 1 (described later), inside. The main body 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 are connected to the pair of elements 115, respectively, on 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 pressure fluid introduced through the coupling tube 116.

[0015] 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 inside. An example of the transmission member 120 is an actuation plate 121. The actuation 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 a pressing arm 17 and a lever 16 (a reaction member) (described later). The switch component 118 includes a plurality of contacts 40 (described later) and changes the 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, constituting 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 of the manual reset mechanism 2, the contacts 40, which are in a predetermined conductive state, can be manually switched to a different conductive state.

[0016] FIG. 2 is a perspective view of the microswitch 1, and FIG. 3 is a plan view of the microswitch 1. Note that FIG. 2 omits a reset shaft 71 and a reset plate 72, which will be described later and which constitute a manual reset mechanism 2, which will be described later. 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 defines an accommodation space 11 inside for accommodating various components. A connecting portion 13 that protrudes toward the rear side X2 is formed on a rear wall 12 of the box portion 10. The connecting portion 13 is formed in a plate shape extending in the up-down 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 left-right 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 as to be rotatable around the shaft. In other words, a pair of levers 16 is provided. In this embodiment, "rotation" means rotation in both forward and reverse directions around the rotation shaft 15 within a predetermined angular range.

[0017] 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 about the pivot shaft 15 in a forward direction a and a backward direction b. 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 about the pivot shaft 15 in the forward direction a when subjected to an external force. An example of the external force is a force generated in response to a change 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 a pressure arm 17 (shown in FIG. 3 ). The pressure arm 17 is formed into a generally L-shaped shape in a plan view by bending a metal plate.

[0018] The tip of the pressing arm 17 is disposed on the upper side Z1 of the front end of the lever 16 except for the inward portion in the left-right direction Y, and is displaced downward Z2 in response to a force applied to the sensitive member, causing the lever 16 to rotate in the forward direction a about the rotation shaft 15. A receiving portion 18 is formed on the plate surface of the lever 16. As shown in FIG. 4, the receiving portion 18 is formed by protruding an intermediate portion of the plate surface of the lever 16 in the front-rear direction X toward the upper side Z1, and has a V-shaped cross-section that opens to the lower side Z2. An operating shaft 20 whose axis extends in the up-down direction Z is supported by the receiving portion 18. The operating shaft 20 is a shaft member that converts the rotational movement of the lever 16 into forward and backward movement in the up-down direction Z.

[0019] 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 is in sliding contact with the V-shaped inner surface of the receiving portion 18 of the lever 16 and is pressed toward the lower side Z2. Meanwhile, the lower end of the operating shaft 20 forms an engaging portion 22 that engages with a switching means 30, which will be described later. The switching means 30 is configured to switch the conduction state of a contact 40 arranged in the accommodation 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 having a movable contact 42, which will be described later, that is biased toward the upper side Z1 or the lower side Z2 by the snap piece 32.

[0020] 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 pressing 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 pressing 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 the 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 a lower limit position (not shown), the snap piece 32 can no longer maintain the 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. Then, 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 the biasing direction toward the upper side Z1. When the engaging portion 22 of the operating shaft 20 moves toward the upper side Z1 beyond an upper limit position (not shown) (a position Z1 above the above-mentioned lower limit position), the snap piece 32 can no longer maintain the 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.

[0021] The contact 40 is a conductive member made of a conductive material and includes a pair of fixed contacts 41 fixed within the housing space 11 and a movable contact 42 disposed between the pair of fixed contacts 41. The pair of fixed contacts 41 includes 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 disposed above the first fixed contact 41A. The movable contact 42 is fixed to the front end of the conductive piece 33 and displaces toward the upper side Z1 or the lower side Z2, which is the biasing direction of the snap piece 32, to come into contact with the first fixed contact 41A or the second fixed contact 41B, thereby establishing electrical continuity with the first fixed contact 41A or the second fixed contact 41B.

[0022] As described above, the movable contact 42 can perform a reversal operation to switch the conductive destination by changing the biasing direction by reversing the snap piece 32 in the up-down direction Z. Specifically, the movable contact 42 can be switched between a first conductive state ("movable-fixed A: ON" in the tables of FIGS. 7 to 9) in which it is displaced downward Z2 and is conductive to the first fixed contact 41A, and a second conductive state ("movable-fixed A: OFF" in the tables of FIGS. 7 to 9) in which it is displaced upward Z1 and is conductive to the second fixed contact 41B. In the following description, the "first conductive state" may be referred to as the first conductive state (movable-fixed A: ON), and the "second conductive state" may be referred to as the second conductive state (movable-fixed A: OFF).

[0023] 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 a 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, the second fixed contact 41B, and the 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 mounting portion 51 at the lower end to which an electric wire (not shown) is connected is bent using a fastening member 123 (see Figure 1), and the mounting portion 51 is fixed along the bottom wall of the box portion 10.

[0024] In this embodiment, the microswitch 1 has a snap piece 32. Therefore, in the case where the microswitch 1 does not have a mechanism related to the manual reset mechanism 2 (described later), i.e., in the case of a so-called auto-reset type microswitch, the microswitch operates as follows when the lever 16 rotates. Specifically, as shown in the table of FIG. 7, the lever 16, which is in the initial state as indicated by "Initial (0 MPa)," rotates in the direction of advance a due to an increase in fluid pressure as indicated by "Pressure Rising" in the table of FIG. 7. As a result, the operating shaft 20 descends. When the engaging portion 22 moves to the lower side Z2 beyond the lower limit position where the snap piece 32 can no longer maintain the biasing direction of the lower side Z2, the snap piece 32 reverses, causing a reversal action in the movable contact 42, switching the conduction state from the first conduction state (operating-fixed A: ON) to the second conduction state (operating-fixed A: OFF). The state of the lever 16 when this reversal action occurs is indicated by "Above Rising Actuation Value" in the table of FIG. 7. The above-mentioned auto-reset type microswitch is also called an automatic return type microswitch.

[0025] In this embodiment, the position where the reversal occurs when the lever 16 passes in the traveling direction a is the first reversal position (referred to as the rising point in FIGS. 7 to 9) in the rotation direction of the lever 16. According to this configuration, for example, by incorporating the microswitch 1 in a pressure switch, it is possible to configure a high-pressure cutoff switch that switches the conduction state from the first conduction state to the second conduction state when an abnormally high pressure occurs. In the case of an auto-reset type (or automatic return type) microswitch as described above, as shown in "During Pressure Decrease" in the table of FIG. 7, after the reversal operation (i.e., after cutoff), the lever 16 rotates in the retraction direction b due to a decrease in fluid pressure, and the operating shaft 20 rises. When the lever 16 returns to the first conduction state before the switch ("initial (0 MPa)" shown in FIG. 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 the biasing direction of the upper side Z1, the snap piece 32 reverses, and the movable contact 42 undergoes a reversal operation. As a result, the conduction state is switched from the second conduction state to the first conduction state.

[0026] In this embodiment, the position where the reversal action occurs when the lever 16 passes in the backward direction b is defined as the second reversal position (referred to as the downward point in FIGS. 7 to 9) in the rotation direction of the lever 16. According to this configuration, the rotation range of the lever 16 includes the first reversal position (upward point) where the reversal action occurs when the lever 16 passes in the forward direction a, and the second reversal position (downward point) where the reversal action occurs when the lever 16 passes in the backward direction b. In this manner, the microswitch 1 of this embodiment is configured as a switch in which the first reversal position, which is a set value serving as a trigger for executing high-pressure cutoff, and the second reversal position, which is a set value serving as a trigger for returning to the original state, are different positions. 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).

[0027] The microswitch 1 configured as described above includes a manual reset mechanism 2. The manual reset mechanism 2 is used, for example, when the above-mentioned high-voltage cutoff occurs, to maintain the second conductive state for the purpose of subsequent maintenance work by an operator, and to release the second conductive state and return to the first conductive state after the maintenance work is completed. 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 up-down direction Z and opening on the top wall of the box portion 10, a spring bearing portion 62 continuing from the lower end of the shaft support portion 61, having an inner diameter larger than that of the shaft support portion 61, and extending downward Z2, and a button support portion 63 continuing from the lower end of the spring bearing portion 62, having an inner diameter larger than that of the spring bearing portion 62, and opening on the bottom wall of the box portion 10.

[0028] A reset member 70 (defining portion) that defines the position of the lever 16 in the rotational direction is inserted into the mounting hole 60. The reset member 70 includes a cylindrical reset shaft 71 that extends 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 portion 72a with four notched corners, and a pressing portion 72b that protrudes outward in the horizontal direction Y from an outer edge of the main body portion 72a in the horizontal direction Y. The lower surface of the pressing portion 72b is configured to be able 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, the pressing portion 72b presses the lever 16 downward Z2, thereby defining the position of the lever 16 in the rotational direction. That is, the reset shaft 71 moves the reset plate 72 back and forth in the vertical direction Z, and this back and forth movement of the reset plate 72 determines the position of the lever 16 in the rotation direction.

[0029] Furthermore, the reset plate 72 can be displaced in the vertical direction Z relative to the reset shaft 71 by screwing the threadedly engaged 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 restricts the reset shaft 71 from being displaced 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 determines the lower end position L of the reset shaft 71. Meanwhile, a second E-ring 74 is attached to the lower end side 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 a step portion at the boundary between the spring receiving portion 62 and the button support portion 63. 4, the reset shaft 71 is restricted from being displaced 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.

[0030] A reset spring 75 (biasing means) is housed between the second E-ring 74 and the upper end of the spring bearing portion 62. That is, 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 portion that an operator operates when displacing the reset shaft 71 in the vertical direction Z, and is formed in an elliptical shape in a bottom view as shown in FIG. 6. The reset button 76 is supported by the button support portion 63 and can be pressed toward the upper side Z1 up to a step portion at the boundary between the button support portion 63 and the spring bearing portion 62. By pressing 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 appropriate, but in this embodiment, when the reset button 76 is pressed down to its limit, the reset shaft 71 is displaced to the upper end position H. On the other hand, when the reset button 76 is not pressed down, the biasing force of the reset spring 75 automatically positions the reset shaft 71 at the lower end position L.

[0031] Next, the operation of the microswitch 1 will be described. FIG. 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. FIG. 9 is a schematic diagram showing the operation of the microswitch 1 equipped with the manual reset mechanism 2 after the "pressure is decreasing" state. Note that in FIGS. 8 and 9 (FIG. 10), the rotating shaft 15, lever 16, and reset plate 72 are shown in schematic shapes rather than their actual shapes to avoid cluttering the illustration. First, when the reset button 76 is not operated, as shown in "Initial (0 MPa)" in the table of FIG. 8, the lever 16 is in contact with the reset plate 72 and is positioned between the first reversal position and the second reversal position. In this state, the movable contact 42 is electrically connected to the first fixed contact 41A, and is in the first conductive state (operated-fixed A: ON).

[0032] From this state, as shown in the table of FIG. 8 under "Pressure Rising," 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 is displaced in the forward direction a and exceeds the first reversal position (rising point), as shown in the table of FIG. 8 under "Above Rising Trigger Value." This causes the movable contact 42 to reverse, displace to the upper side Z1, and conduct to the second fixed contact 41B, switching to the second conduction state (operating-fixed A: OFF). If the fluid pressure drops from this state, the lever 16 rotates in the backward direction b, as shown in the table of FIG. 8 under "Pressure Decreasing." This rotation is then restricted by the lever 16 abutting against the reset plate 72, as shown in the table of FIG. 9 under "Below Decreasing Trigger Value = Waiting for Release."

[0033] 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 toward the backward direction b, is restricted between the first reversal position (upward point) and the second reversal position (downward point) is defined as a "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 a set value serving as a trigger for executing high-pressure cutoff, and the second reversal position (downward point), which is a set value serving as a trigger for returning 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 rotation direction of the lever 16 is between the first reversal position (ascending point) and the second reversal position (descending point), similar to the rotation direction position shown as "initial 0 MPa" in the table of Figure 8, but no reversal operation of the movable contact 42 occurs, and the second conductive state is maintained.

[0034] This allows the system to issue an alarm in the second conduction state, for example. Even if an abnormality occurs and is automatically resolved, the system can still notify the operator of the abnormality. This allows the operator to perform maintenance, which is useful. After the maintenance is completed, 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). Therefore, as shown in FIG. 4, the reset button 76 is pushed upward Z1, displacing the reset shaft 71 and the reset plate 72 upward Z1. As a result, the lever 16 can be rotated in the backward direction b and pass through the second reversal position, as shown in the table in FIG. 9 under "Released (Button Pressed)." At this time, a reversal operation occurs, and the movable contact 42 switches from the second conductive state (moving-fixed A: OFF) to the first conductive state (moving-fixed A: ON).

[0035] The position where the lever 16 is rotated in the backward direction b 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 located 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 restricting position P1 is located on the lower side Z2 (the other axial side). The reset plate 72 (reset member 70) is supported so as to be displaceable between the reset position P2 and the restricting position P1. Finally, when the reset button 76 is released from being pressed, the reset shaft 71 is automatically displaced to the lower side Z2 by the biasing force of the reset spring 75, and the reset plate 72 returns to its original position (restricting position P1), completing the operation of the manual reset mechanism 2.

[0036] 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 restricting 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 restricting position P1 and can be moved to the reset position P2 may be used as the restricting position P1. Furthermore, any position that meets the definition of the reset position P2 and can be moved to the restricting position P1 may be used as the reset position P2. Next, the adjustment operation of the manual reset mechanism 2 will be described. FIG. 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 or the like of the abnormality. In other words, it is necessary to change from the second conduction state to the first conduction state only when the reset button 76 is pressed. Therefore, it is necessary to ensure that the lever 16 is accurately positioned at the restricting position P1 and maintained in that state when the reset button 76 is not operated, and that when the reset button 76 is operated, the lever 16 moving in the backward direction b reliably passes through the reset position P2, and for this reason it is necessary to accurately determine the first reversal position (ascending point) and the second reversal position (descending point).

[0037] Therefore, the manual reset mechanism 2 is adjusted. First, as shown in "Initial" and "Forced Operation" in the table of FIG. 10, the lever 16 in the initial state is forcibly rotated in the forward direction a by the reset plate 72 to a position where the first conductive state changes to the second conductive state, i.e., the first reversal position (rising point). At this time, as described above, it is useful to move the reset plate 72 downward Z2 relative to the reset shaft 71 by screwing the reset plate 72, because this allows fine adjustment of the position of the reset plate 72. Next, as shown in "Looking for the descending point" in the table of FIG. 10, the lever 16 is rotated in the backward direction b by the reset plate 72 to a position where the second conductive state changes to the first conductive state, i.e., the second reversal position (falling point).

[0038] At this time, it is useful to move the reset plate 72 upward Z1 relative to the reset shaft 71 by screwing it, since this allows 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 in "Adjustment" in the table of FIG. 10, the lever 16 is rotated in the direction of travel a by the reset plate 72, and the lever 16 is positioned between the first reversal position (ascending point) and the second reversal position (descending point), and this position is set to the restriction position P1. This completes the adjustment operation of the manual reset mechanism 2.

[0039] Note that, in contrast to the above-described adjustment operation, it is also possible to position the lever 16 at the second reversal position (descent point), then at the first reversal position (ascension point), and then perform the above-described final adjustment toward the second reversal position (descent point) to define the restriction position P1. However, according to this embodiment, by performing 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.

[0040] According to the above-described embodiment, the position of the lever 16 in the rotational direction 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 position of the lever 16 in the rotational direction. Therefore, the restricting 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 restricting position P1 can be accurately maintained, thereby accurately controlling the reversing 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 a structure in which the state of the movable contact 5 is unstable due to dimensional variations in the adjusting plate 12 and the reversing spring 13, and the tightening amount of the adjusting plate 12 varies due to vibration, etc., this configuration accurately operates the manual reset mechanism 2 (reset mechanism) by controlling the position of the reset member 70. Therefore, this configuration prevents unintended auto-resetting and reliably performs resetting when necessary. Therefore, a microswitch 1 (manual reset type microswitch) with high operational reliability can be provided.

[0041] Furthermore, according to this embodiment, the reset member 70 includes the reset shaft 71 and the 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 restriction position P1 and the reset position P2.

[0042] 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 reset plate 72 is automatically displaced to the restriction position P1 by the biasing force of the reset spring 75 (biasing means), and can be positioned at the restriction position P1.

[0043] Furthermore, according to this embodiment, the pressure responsive switch 100 can be configured using the microswitch 1 (manual reset type microswitch) that has high operational reliability.

[0044] The above-described embodiments merely illustrate typical aspects of the present invention, and the present invention is not limited thereto. In other words, various modifications can be made without departing from the gist of the present invention. Such modifications, as long as they comprise the configuration of the microswitch 1 of the present invention, are naturally included 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 as to be 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 directions of the actuating shaft 20, the switching means 30, and the manual reset mechanism 2 accordingly.

[0045] 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, although 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. That is, in this embodiment, the pressure responsive switch 100 is used as a pressure switch that detects pressure changes by introducing the fluid to be detected (here, the refrigerant circulating in the refrigeration cycle) through the coupling tube 116 and applying the pressure of the fluid to be detected directly to a sensitive member such as a bellows or diaphragm. However, the use of the pressure responsive switch 100 is not limited to this. That is, a temperature switch can be configured 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 member, 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 the temperature change detected by the temperature-sensitive tube, and the resulting force is transmitted to the lever 16 (responsive member), thereby changing the conductive state of the contacts.

[0046] In this embodiment, the microswitch 1 includes a pair of levers 16 and corresponding actuating shafts 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 various other microswitches. In this embodiment, when the reset button 76 is not pressed, the reset shaft 71 automatically moves to its pre-pressed position due to 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 move the reset shaft 71 to its pre-pressed position. By keeping the reset button 76 pressed, the microswitch 1 can be used as the auto-reset (automatic return) microswitch described above. The microswitch 1 can also be used as the auto-reset microswitch described above by removing the reset member 70, such as the reset shaft 71 and reset plate 72, from the microswitch 1. [Explanation of symbols]

[0047] a Direction of travel b Regressive direction P1 Restricted position P2 reset position 1 microswitch 15 Rotating shaft 16 Lever 41 Fixed contact 42 Movable contact 70 Reset member (regulating part)

Claims

1. 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.

2. 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.

3. 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.

4. A pressure responsive switch equipped with the microswitch according to any one of claims 1 to 3.

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