Microswitch and pressure-activated switch

Abstract

To provide a microswitch and a pressure-activated switch that can stably maintain the conductive state of a contact.SOLUTION: Switching means 50 of a microswitch 1 includes an inner spring 60, an outer spring 70, and a reversing spring 80. The inner spring 60 is deformed with the movement of an operating shaft 20, and the reversing spring 80 biases the outer spring 70 in response to the deformation of the inner spring 60, and the outer spring 70 is biased by the reversing spring 80 to press a movable contact 44 toward a fixed contact 41. The movement range of the operating shaft 20 includes a reversing position γ where a reversing action occurs when the operating shaft 20 passes through, and the inner spring 60 is provided with a hole 90 for being in a bent deformed state when the operating shaft 20 is located at the reversing position γ. When the inner spring 60 is in a deformed state, a biasing force that maintains the state in which the outer spring 70 presses the movable contact 44 toward the fixed contact 41 is generated by the reversing spring 80.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] Conventionally, a microswitch (mechanical switch) that switches the conductive state of a contact is known (see, for example, Patent Document 1). As shown in FIG. 1 of Patent Document 1, the microswitch described in Patent Document 1 includes a movable contact 2a provided between a fixed contact 4 and a contact 9, a leaf spring 3 that turns the movable contact 2a ON and OFF, and a pressing piece 5 that acts on the leaf spring 3. The leaf spring 3 includes an inner operating piece 3a pressed by the pressing piece 5, an outer operating piece 3b connected to the movable contact 2a, and a leaf spring 3c that connects the inner operating piece 3a and the outer operating piece 3b. In this microswitch, when the pressing force of the pressing piece 5 and the elastic force of the leaf spring 3 are balanced, the movable contact 2a separates from the fixed contact 4 and turns OFF. On the other hand, when the pressing force of the pressing piece 5 reaches a predetermined pressure or more, the inner operating piece 3a is pressed down, which reverses the leaf spring 3c to press up the outer operating piece 3b, and the movable contact 2a comes into contact with the fixed contact 4 and turns ON. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-63417 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned microswitch, for example, when the pressing piece 5 is pressed down from the OFF state in which the movable contact 2a and the fixed contact 4 are separated, and the leaf spring 3c is about to reverse when the pressing piece 5 is pressed down, the movable contact 2a is likely to repeatedly come into contact with and separate from the fixed contact 4, resulting in a chattering phenomenon. Therefore, it is difficult to stably maintain the conductive state of the movable contact 2a in the state immediately before the leaf spring 3c reverses. This is likely to be noticeable when the microswitch is mounted in equipment that is susceptible to unintended external forces due to vibrations, pressure fluctuations, etc., such as a pressure-responsive switch that detects the pressure of a refrigerant in a refrigeration cycle system.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a microswitch and a pressure responsive switch capable of stably maintaining the conductive state of the contacts. [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 including a movable contact provided between a pair of fixed contacts, an operating shaft that moves in an advancing and retreating direction, and a switching means that performs a reversing operation in association with the movement of the operating shaft to cause the movable contact to be conductive to one or the other of the pair of fixed contacts, the switching means including an operating spring connected to the operating shaft, an application spring that holds the movable contact, and a reversing spring that connects the operating spring and the application spring, the operating spring being provided so as to be deformable in association with the movement of the operating shaft, and the reversing spring being adapted to change the application position in accordance with the deformation of the operating spring. the operating shaft is provided with a stiffness reducing means for reducing the stiffness of the operating spring when the operating shaft is positioned at the reversal position, and when the operating spring is in the deformed state, a biasing force is generated by the reversal spring to maintain the operating spring pressing the movable contact against one or the other of the pair of fixed contacts.

[0007] According to the present invention, by providing the stiffness reducing means in the operating spring, the operating spring can be deformed when the operating shaft is in the reversing position, i.e., immediately before the reversing operation occurs. Then, by the operating spring being in the deformed state, the reversing spring can generate a biasing force that maintains the state in which the working spring presses the movable contact against the fixed contact. Therefore, even immediately before the reversing operation, the movable contact can be reliably maintained in a state pressed against the fixed contact, and chattering phenomena can be suppressed even when an unintended external force such as vibration or pressure fluctuation occurs. Therefore, a microswitch capable of stably maintaining the conductive state of the contacts can be provided.

[0008] In this case, the fixed contact may include a first fixed contact and a second fixed contact arranged on the retraction side of the first fixed contact in the forward / retraction direction, and the reversal positions may include a first reversal position where the reversal action occurs after the operating shaft passes toward the forward side in the forward / retraction direction, and a second reversal position where the reversal action occurs after the operating shaft passes toward the retraction side, and when the operating shaft moving toward the forward side is positioned at the first reversal position, the movable contact may be pressed toward the first fixed contact, and when the operating shaft moving toward the retraction side is positioned at the second reversal position, the movable contact may be pressed toward the second fixed contact. With this configuration, the present invention can also be applied to a type of microswitch that has different reversal positions (first reversal position) where a reversal operation occurs in which the movable contact switches its electrical connection from the first fixed contact to the second fixed contact, and where a reversal position (second reversal position) in which the movable contact switches its electrical connection from the second fixed contact to the first fixed contact, and can maintain the movable contact pressed toward the fixed contact immediately before the reversal operation.

[0009] In addition, the switching means preferably includes an inner spring as the operating spring formed in a plate shape extending in a direction intersecting the forward / reverse direction, an outer spring as the working spring formed in a plate shape surrounding the inner spring, and the reversing spring, the inner spring having an abutment portion that abuts against the operating shaft, and the stiffness reducing means reduces the stiffness of the inner spring from the side where the abutment portion is located toward the side where the connection portion with the reversing spring is located. According to this configuration, the stiffness reducing means reduces the stiffness of the inner spring toward the side where the connection portion is located, so that the side where the connection portion of the inner spring is located can be more easily deformed than the side where the operating shaft of the inner spring is located. This makes it easier to maintain the deformed state of the inner spring on the connection portion side. Therefore, immediately before the reversing operation, it is easier to maintain the biasing force of the reversing spring against the outer spring, and the state in which the outer spring presses the movable contact toward the fixed contact can be stably maintained. Furthermore, with this configuration, it is easy to increase the rigidity of the inner spring on the side where the operating shaft is located, thereby improving the durability of the inner spring on the side where the operating shaft is located.

[0010] The stiffness reducing means may be a hole penetrating the inner spring in the thickness direction. According to this configuration, the stiffness reducing means can be provided to the microswitch by a simple method of forming a hole in the inner spring.

[0011] Moreover, it is preferable that the width dimension of the hole increases toward the connecting portion. With this configuration, by increasing the width dimension of the hole toward the connecting portion, the volume of the inner spring can be made smaller toward the connecting portion side and larger toward the abutting portion side. Therefore, the rigidity of the inner spring can be reduced toward the connecting portion side, and the side of the inner spring where the connecting portion is located can be made more easily deformed than the side of the inner spring where the operating shaft is located. This makes it easier to maintain the deformed state of the inner spring on the connecting portion side.

[0012] The stiffness reducing means may be formed by cutting the inner spring in the width direction. With this configuration, the stiffness reducing means can be provided in the microswitch by a simple method of cutting the inner spring to form the cutout.

[0013] The pressure responsive switch of the present invention is characterized by comprising the microswitch described above. With this configuration, it is possible to construct a pressure responsive switch by mounting a microswitch capable of stably maintaining a conductive state of the contacts. Effect of the Invention

[0014] According to the present invention, it is possible to provide a microswitch and a pressure responsive switch that can stably maintain the conductive state of the contacts. [Brief description of the drawings]

[0015] [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. [Diagram 2] FIG. [Diagram 3] A cross-sectional view taken along line A-A in Figure 2. [Figure 4] FIG. [Diagram 5] FIG. 4 is a schematic diagram showing a switching unit in an initial state. [Figure 6] FIG. 2A is a schematic diagram showing a switching means in a state where the operating shaft is located at a first reversal position, and FIG. 2B is a schematic diagram showing a switching means not including a stiffness reducing means in a state where the operating shaft is located at the first reversal position. [Figure 7] FIG. 11 is a plan view showing a part of a switching means in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of the present invention will be described below. The microswitch 1 according to this embodiment is mounted on a pressure responsive switch 100 that detects changes in fluid pressure or temperature, for example, and detects changes in pressure or temperature of a working medium such as a refrigeration cycle, an automobile, or an actuator for various controls.

[0017] In the following description, the axial direction of the operating shaft 20, which will be described later, is indicated by an arrow Z in the drawings, and is referred to as the "upper-lower direction Z". One side of the upper-lower direction Z is referred to as the "lower side Z1", and the other side is referred to as the "upper side Z2". The upper-lower direction Z is the "advance-retraction direction" in the present invention, the lower side Z1 is the "advance side" in the present invention, and the upper side Z2 is the "retreat side" in the present invention. The horizontal directions (crossing directions in the present invention) intersecting the upper-lower direction Z are indicated by arrows X and Y, and are referred to as the "forward-rear direction X" and the "left-right direction Y", respectively. One side of the forward-rear direction X is referred to as the "front side X1", the other side as the "rear side X2", 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". The definitions of these directions are merely for the convenience of description, and do not necessarily match 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.

[0018] As shown in FIG. 1, the pressure-responsive switch 100 includes a case 110 having a generally rectangular shape. The case 110 includes a C-shaped main body frame 111 that opens to the lower side Z1, and a cover (not shown) that closes the opening of the main body frame 111, and accommodates various components such as a microswitch 1 (described later) inside. The main body frame 111 is formed by bending a metal plate material, and includes a front wall portion 112, a side wall portion 113, a rear wall portion 114, and a top wall portion 115. A pair of elements 116 and a pair of joint tubes 117 that are respectively connected to the pair of elements 116 are connected to the rear wall portion 114 of the case 110. The element 116 includes a sensitive member such as a bellows or a diaphragm (not shown) inside. The sensitive member is deformed or displaced in the front-rear direction X in response to a pressure change of the pressure fluid introduced through the joint tube 117.

[0019] A pair of left and right transmission mechanisms 118 and a pair of left and right switch components 119 are housed inside the case 110. The transmission mechanism 118 includes a reinforcing plate 120 formed into a C-shape that opens to the upper side Z2 by bending a metal plate material, and a transmission member 121 is housed inside the reinforcing plate 120. An example of the transmission member 121 is an actuation plate 122, which receives a force that causes the above-mentioned sensitive member to deform or displace as an external force, rotates around a rotation shaft 123, and converts the external force into an operating force, and transmits the operating force to a lever 17 described later. The switch component 119 is configured with a plurality of contacts 40 described later, and changes the conductive state of the contacts 40 upon receiving the above-mentioned operating force. A pair of switch components 119 are provided adjacent to each other in the left-right direction Y, forming a dual-type microswitch 1. FIG. 2 is a perspective view of the microswitch 1, and FIG. 3 is a cross-sectional view taken along line A-A in FIG. 2.

[0020] As shown in FIG. 2, the microswitch 1 includes a box portion 10. The box portion 10 is formed, for example, of a resin material in a substantially cubic shape, and the inside thereof forms an accommodation space 11 for accommodating various components. A connection portion 13 protruding toward the rear side X2 is formed on a rear wall 12 of the box portion 10. The connection portion 13 is formed in a plate shape extending in the vertical direction Z, and is fixed to a top wall portion 115 of a case 110 of the above-mentioned pressure responsive switch 100. A rectangular box-shaped fixing member 15 is attached to an upper wall 14 of the box portion 10. In this embodiment, a pair of fixing members 15 are attached side by side in the left-right direction Y. A rotating shaft 16 extending in the left-right direction Y is fixed to a side wall of each fixing member 15, and a lever 17 is attached to the rotating shaft 16 so as to be rotatable around the shaft. That is, a pair of levers 17 are provided. In this embodiment, "rotation" means forward and reverse rotation around the rotating shaft 16 within a predetermined angle range. The lever 17 is an operating fitting made of a metal material and formed into a plate shape, and extends from the rotation shaft 16 to the front side X1 and is provided rotatably about the rotation shaft 16 on one side a and the other side b.

[0021] In the initial state shown in FIG. 2, the lever 17 is biased toward the other side b by the biasing force of the switching means 50 described later, and extends at an incline so as to be located on the upper side Z2 from the rear end supported by the rotating shaft 16 toward the front end. The lever 17 rotates toward the one side a around the rotating shaft 16 when subjected to an external force. An example of the external force is a force generated in response to a pressure change of the refrigerant in the above-mentioned refrigeration cycle. Such a force is applied to a sensitive member (not shown) mounted on the pressure switch, and is transmitted to the lever 17 via the transmission mechanism 118. A receiving portion 18 is formed on the plate surface of the lever 17. As shown in FIG. 3, the receiving portion 18 is formed by protruding a middle portion of the plate surface of the lever 17 in the front-rear direction X to the upper side Z2, and has a V-shaped cross-sectional surface that opens to the lower side Z1. The receiving portion 18 supports an operating shaft 20 whose axis extends in the vertical direction Z.

[0022] The actuating shaft 20 is a shaft member that converts the rotational motion of the lever 17 into a forward and backward motion in the vertical direction Z, and moves in the vertical direction Z to act on a switching means 50 described later. The actuating shaft 20 is connected to the box part 10 so as to be movable forward and backward in the vertical direction Z while being inserted into an insertion hole 19 that penetrates the upper wall 14 of the box part 10 in the vertical direction Z. The upper end of the actuating shaft 20 constitutes a pressed part 21 that is pressed by the lever 17. In this embodiment, the pressed part 21 is in sliding contact with the V-shaped inner surface of the receiving part 18 of the lever 17 and is pressed to the lower side Z1. On the other hand, the lower end of the actuating shaft 20 constitutes an engaging part 22 that engages with the switching means 50 described later. The actuating shaft 20 is held by a seal member 30 that closes the gap between the actuating shaft 20 and the insertion hole 19, and is connected to the box part 10. The seal member 30 provides an airtight seal between the operating shaft 20 and the insertion hole 19, and is provided to prevent the outside atmosphere or foreign matter of the microswitch 1 from entering the housing space 11 from between the operating shaft 20 and the insertion hole 19. Note that if the above-mentioned intrusion of the outside atmosphere or foreign matter into the housing space 11 can be tolerated, the seal member 30 does not need to be provided. In other words, the inner diameter of the insertion hole 19 may be made smaller according to the outer diameter of the operating shaft 20, and the operating shaft 20 may be guided by the insertion hole 19 in the upper wall 14 of the box portion 10.

[0023] The seal member 30 is formed in a cylindrical shape using, for example, a flexible resin material. The upper end opening edge 31 of the seal member 30 covers the operating shaft 20 in the circumferential direction around the shaft, and the lower end opening edge 32 of the seal member 30 covers the opening edge of the insertion hole 19, so that the airtightness in the accommodation space 11 is set to have, for example, at least several tens of kPa of airtightness from the accommodation space 11 side. With this configuration, even if the pressure responsive switch 100 is used in an atmosphere of a flammable fluid, the flammable fluid can be prevented from entering the accommodation space 11, and the risk of ignition due to sparks generated by the operation of the microswitch 1 can be reduced. The setting of the airtightness of the accommodation space 11 is not limited to the above, and can be arbitrarily set according to the expected usage environment. For example, in a case where the intrusion of foreign matter into the accommodation space 11 is prevented and the intrusion of a gaseous fluid can be permitted, the airtightness of the accommodation space 11 may be set to a degree that prevents the intrusion of foreign matter.

[0024] As shown in FIG. 3, a contact 40 is installed in the storage space 11 of the box part 10. The contact 40 is a conductive member made of a conductive material, and includes a pair of fixed contacts 41 fixed in the storage space 11, and a movable contact 44 arranged between the pair of fixed contacts 41. The pair of fixed contacts 41 is composed of a first fixed contact 42 and a second fixed contact 43. The first fixed contact 42 is fixed to the inner wall of the box part 10 while facing the upper side Z2. The second fixed contact 43 is fixed to the inner wall of the box part 10 while facing the lower side Z1 and arranged above the first fixed contact 42. The movable contact 44 is fixed to a contact holding part 72 of the outer spring 70 described later, and is displaced to the upper side Z2 or the lower side Z1 to abut against the first fixed contact 42 or the second fixed contact 43, and is capable of being electrically connected to the first fixed contact 42 or the second fixed contact 43. In the accommodation space 11 of the box portion 10, between the operating shaft 20 and the contact 40, a switching means 50 for switching the conductive state of the movable contact 44 (contact 40) is provided.

[0025] The switching means 50 is a part that performs a reversing operation in association with the movement of the operating shaft 20 to make the movable contact 44 conductive to one or the other of the first fixed contact 42 and the second fixed contact 43. As shown in Fig. 3, the switching means 50 is a leaf spring formed by bending, for example, a metal plate member, and includes a contact plate 51 fixed to the inner wall of the box part 10. The contact plate 51 includes a bent part 52 curved to the rear side X2 by folding back to the front side X1 from a position fixed to the inner wall of the box part 10, a plate-shaped inner spring 60 (operating spring) that extends to the front side X1 continuously with the center part of the bent part 52 in the left-right direction Y and extends in the front-rear direction X and the left-right direction Y (i.e., the intersecting direction), an outer spring 70 (acting spring) that is continuous with the bent part 52 and is formed in a plate shape surrounding the inner spring 60, and a reversing spring 80 that connects the inner spring 60 and the outer spring 70. As shown in Fig. 4, the inner spring 60 has a wide portion 61 that constitutes the rear side X2 portion. The wide portion 61 is formed in a generally rectangular shape in a plan view, and as shown in Fig. 5, it extends at an angle from the rear side X2 toward the front side X1 so as to be located on the upper side Z2.

[0026] The wide portion 61 is formed with an engagement hole 62 penetrating in the vertical direction Z, and the engagement portion 22 of the operating shaft 20 is engaged with the engagement hole 62 in a state where it is inserted toward the lower side Z1. That is, the inner spring 60 is connected to the operating shaft 20. As a result, the inner edge of the engagement hole 62 abuts against the outer surface of the operating shaft 20, forming an abutment portion 63. A narrow portion 64 having a smaller dimension in the left-right direction Y than the wide portion 61 is formed continuously on the front side X1 of the wide portion 61. The narrow portion 64 is formed in a substantially rectangular shape in a plan view, and extends at an angle from the rear side X2 toward the front side X1 so as to be located on the upper side Z2. A first engagement protrusion 65 protruding to the front side X1 is formed at the center in the left-right direction Y of the front end edge of the narrow portion 64. A hole portion 90 penetrating in the vertical direction Z (plate thickness direction) is formed at the center of the plate surface of the narrow portion 64.

[0027] The formation of the hole 90 reduces the volume of the narrow portion 64, thereby reducing the rigidity of the inner spring 60. That is, the hole 90 constitutes a rigidity reducing means in the present invention. In this embodiment, the hole 90 is formed in a substantially equilateral triangular shape with an acute angle facing the side where the abutment portion 63 of the rear side X2 is located. That is, the dimension of the hole 90 in the left-right direction Y increases toward the first connecting portion A. As a result, the volume of the front side X1 portion of the inner spring 60 gradually decreases toward the front side X1 compared to the volume of the rear side X2 portion, and in particular, the rigidity of the inner spring 60 decreases from the side where the abutment portion 63 of the inner spring 60 is located toward the front side X1 where the first connecting portion A (connecting portion) described later is located.

[0028] The outer spring 70 has a pair of left and right side portions 71 extending continuously to the bent portion 52 toward the front side X1. The left side portion 71 of the pair of side portions 71 is disposed at an interval in the left-right direction Y from the edge of the left side Y1 of the wide portion 61 of the inner spring 60, and the right side portion 71 of the pair of side portions 71 is disposed at an interval in the left-right direction Y from the edge of the right side Y2 of the wide portion 61 of the inner spring 60, and each side portion 71 extends toward the front side X1. A contact holding portion 72 is formed on the front end edge of the side portion 71, connecting and extending each side portion 71. The contact holding portion 72 is disposed at an interval on the front side X1 of the inner spring 60, and is formed in a plate shape whose width dimension in the left-right direction Y decreases toward the front side X1. As shown in Fig. 5, the tip of the contact holder 72 is located between the first fixed contact 42 and the second fixed contact 43, and a mounting hole 73 is formed at the tip, penetrating in the up-down direction Z. The above-mentioned movable contact 44 is inserted and fixed in the mounting hole 73. That is, the outer spring 70 holds the movable contact 44. A protruding portion 74 having a substantially rectangular plate shape that protrudes toward the inner spring 60 is formed at the rear end edge of the contact holder 72. A second engagement protrusion 75 that protrudes to the rear side X2 is formed at the center of the rear end edge of the protruding portion 74 in the left-right direction Y, and the second engagement protrusion 75 faces the first engagement protrusion 65 of the inner spring 60 in the front-rear direction X.

[0029] As shown in FIG. 5, the reversing spring 80 is formed by bending a metal plate member into a substantially U-shape that opens to the lower side Z1, and includes an upper wall surface portion 81, a rear wall surface portion 82, and a front wall surface portion 83. The upper wall surface portion 81 is formed into a substantially rectangular shape and extends in the front-rear direction X and the left-right direction Y. The rear wall surface portion 82 is bent from the rear end edge of the upper wall surface portion 81 toward the lower side Z1, and is inclined so as to be positioned slightly inward as it approaches the lower side Z1. A first inclined portion 82a is formed at the lower end of the rear wall surface portion 82, which is inclined so as to be positioned outward as it approaches the lower side Z1. The front end edge of the narrow width portion 64 of the inner spring 60 abuts against the boundary portion between the rear wall surface portion 82 and the first inclined portion 82a, and the first engagement protrusion 65 is inserted through a through hole (not shown). In this manner, the boundary between the rear wall surface portion 82 and the first inclined portion 82a constitutes a first connecting portion A which is a connecting portion between the inner spring 60 and the reversal spring 80.

[0030] The front wall surface portion 83 is bent from the front end edge of the upper wall surface portion 81 toward the lower side Z1, and is inclined so as to be positioned slightly inward as it approaches the lower side Z1. A second inclined portion 83a is formed at the lower end of the front wall surface portion 83, inclined so as to be positioned outward as it approaches the lower side Z1. The rear end edge of the protruding portion 74 of the outer spring 70 abuts against the boundary portion between the front wall surface portion 83 and the second inclined portion 83a, and the second engagement protrusion 75 is inserted through a through hole (not shown). In this way, the boundary portion between the front wall surface portion 83 and the second inclined portion 83a constitutes the second connecting portion B, which is a connecting portion between the outer spring 70 and the reversing spring 80. The reversing spring 80 is contractible in a direction in which the first connecting portion A and the second connecting portion B are brought closer to each other to close the reversing spring 80, and generates a reversing spring load P1 in a direction in which the first connecting portion A and the second connecting portion B are separated from each other to open the reversing spring 80.

[0031] Next, the operation of the microswitch 1 will be described. Here, as an example of the operation, a case where the microswitch 1 is mounted on a pressure responsive switch 100 that detects the pressure of a refrigerant in a refrigeration cycle system and used to detect abnormally high pressure will be described. First, in an initial state where the lever 17 is not rotated, the movable contact 44 is conductive to the first fixed contact 42 as shown in FIG. 5. At this time, the reversing spring 80 of the switching means 50 is inclined so that the position of the first connecting part A is higher than the position of the second connecting part B. Due to this inclination, the oblique reversing spring load P1 passing through the second connecting part B and the first connecting part A of the reversing spring 80 is converted into a contact load P2 in the downward Z1 direction against the outer spring 70. That is, the outer spring 70 is biased toward the downward Z1 and the front side X1 by the reversing spring load P1, and the movable contact 44 is pressed toward the first fixed contact 42 by the contact load P2 in the downward Z1 direction.

[0032] From this state, when the pressure (i.e., external force) of the refrigerant introduced into the element 116 through the joint pipe 117 shown in FIG. 1 suddenly rises, the sensitive member such as a bellows or a diaphragm changes in the front-rear direction X in response to the pressure change. Then, this change is transmitted as an operating force to the lever 17 through the transmission mechanism 118. The lever 17 that receives the operating force (external force) rotates to one side a around the rotating shaft 16 shown in FIG. 3. The rotational motion of the lever 17 is transmitted to the operating shaft 20 through the receiving portion 18 and the pressed portion 21, and the operating shaft 20 is converted into a motion toward the lower side Z1, i.e., the forward movement side. As a result, the operating shaft 20 moves to the lower side Z1, as shown by the arrow toward the lower side Z1 in FIG. 5. When the operating shaft 20 moves, the inner spring 60 is deformed in accordance with the movement.

[0033] Specifically, the contact portion 63 of the inner spring 60 is displaced to the lower side Z1, and with this displacement, the inner spring 60 is deformed toward the lower side Z1 from the bent portion 52 as a starting point in a direction in which the portion of the first connecting portion A is located on the lower side Z1 compared to before deformation. When the inner spring 60 is deformed, the first connecting portion A and the second connecting portion B approach each other, and the reversing spring 80 is deformed so as to contract. Therefore, as shown by the arrow in FIG. 5, the first connecting portion A generates a biasing force in a rearward obliquely upward direction (a direction in which the portion is located on the upper side Z2 as it moves toward the rear side X2), while the second connecting portion B generates a biasing force in a frontward obliquely downward direction (a direction in which the portion is located on the lower side Z1 as it moves toward the front side X1) as shown by the arrow in FIG. Then, with the movement of the operating shaft 20, the biasing direction of the reversing spring 80 against the outer spring 70 gradually changes toward the front side X1. When the state shown in Fig. 6(A) is reached, the inner spring 60 is deflected toward the upper side Z2 starting from the vicinity of the hole 90, compared to the initial state shown in Fig. 5. Therefore, although the inclination of the reversal spring load P1 with respect to the front-rear direction X is gentler than that of the initial state shown in Fig. 5, the inclination of the reversal spring load P1 with respect to the front-rear direction X is maintained. Accordingly, the contact spring load P2, which is the component of the reversal spring load P1 in the up-down direction Z, is also maintained. Note that the working spring is deflected so as to curve toward the upper side Z2 by the projection 74 side being displaced toward the lower side Z1.

[0034] When the operating shaft 20 is further pushed downward Z1 from this state, the balance between the force of the inner spring 60 trying to return to its original shape accumulated due to the bending of the inner spring 60, the force of the reversing spring 80 trying to return to its original shape accumulated due to the deformation of the reversing spring 80, and the force of the outer spring 70 trying to return to its original shape accumulated due to the bending of the outer spring 70 is lost, and a first reversal action (reversal action) occurs in which the contact holding part 72 of the outer spring 70 jumps up toward the upper side Z2 at once. As a result, the movable contact 44 leaves the first fixed contact 42 and comes into contact with the second fixed contact 43, and the conductive destination of the movable contact 44 is switched. In this state, the reversing spring 80 is tilted so that the position of the first connecting part A is lower than the position of the second connecting part B, opposite to the initial state, and the biasing direction of the reversing spring 80 against the outer spring 70 becomes the upper side Z2 and the front side X1. As a result, the movable contact 44 is pressed toward the second fixed contact 43 .

[0035] On the other hand, when the pressure of the refrigerant introduced into the element 116 through the joint tube 117 drops from a state in which the movable contact 44 is electrically connected to the second fixed contact 43, the lever 17 rotates around the rotating shaft 16 shown in FIG. 3 to the other side b, and the operating shaft 20 moves to the upper side Z2, i.e., the retracting side. When the operating shaft 20 moves to the retracting side, the inner spring 60 deforms toward the upper side Z2 from the bent portion 52 as a starting point so that the first connecting portion A is located on the upper side Z2 compared to before deformation. Also, the reversing spring 80 deforms so as to displace the first connecting portion A toward the upper side Z2. And the outer spring 70 bends so as to be curved toward the lower side Z1. Then, the balance between the force of the inner spring 60 trying to return to its original shape accumulated due to the bending of the inner spring 60, the force of the reversal spring 80 trying to return to its original shape accumulated due to the deformation of the reversal spring 80, and the force of the outer spring 70 trying to return to its original shape accumulated due to the bending of the protruding portion 74 of the outer spring 70 is lost, and a second reversal action (reversal action) occurs in which the contact holding portion 72 of the outer spring 70 jumps down toward the lower side Z1 in one go. As a result, the movable contact 44 leaves the second fixed contact 43 and comes into contact with the first fixed contact 42, and the conductive destination of the movable contact 44 is switched.

[0036] In this embodiment, a position where a reversal action occurs within the movement range of the operating shaft 20 is defined as a reversal position γ. The reversal position γ includes a first reversal position γ1 where a first reversal action occurs after the operating shaft 20 moving toward the lower side Z1 passes, and a second reversal position (not shown) where a second reversal action occurs after the operating shaft 20 moving toward the upper side Z2 passes. In this configuration, after the lower end of the operating shaft 20 passes the first reversal position γ1 toward the lower side Z1, a first reversal action occurs in which the movable contact 44 jumps up toward the upper side Z2. On the other hand, after the lower end of the operating shaft 20 passes the second reversal position toward the upper side Z2, a second reversal action occurs in which the movable contact 44 jumps down toward the lower side Z1.

[0037] According to this configuration, for example, by mounting the microswitch 1 on the pressure responsive switch 100, a high-pressure cutoff switch can be configured that switches the conductive destination of the movable contact 44 from the first fixed contact 42 to the second fixed contact 43 when an abnormal high pressure occurs. In this case, the microswitch 1 can be configured as a switch in which the first reversal position γ1, which is a set value as a trigger for executing the high-pressure cutoff, and the second reversal position, which is a set value as a trigger for returning to the original state, are in different positions. However, this is merely an example, and for example, the first reversal position γ1 and the second reversal position may be set to the same position, and there may be only one reversal position γ. In other words, the microswitch 1 can also be configured as a switch in which the first reversal position γ1, which is a set value as a trigger for executing the high-pressure cutoff, and the second reversal position, which is a set value as a trigger for returning to the original state, are in the same position.

[0038] Here, in the switching means 250 of the conventional microswitch 200 shown in FIG. 6(B), the inner spring 260 does not have a hole 90 formed therein as in this embodiment, and the rigidity of the inner spring 260 is greater than that of the inner spring 60 of this embodiment. Therefore, when the lower end of the operating shaft 20 moving toward the lower side Z1 is located at the first reversal position γ1, the inner spring 260 extends in the front-rear direction X without bending. Therefore, the first connecting portion A and the second connecting portion B of the reversal spring 80 are located at the same position in the height direction Z, and the reversal spring load P1 of the reversal spring 80 is not inclined with respect to the front-rear direction X. Therefore, the reversal spring load P1 is not converted into the contact load P2 as described above by following the direction in which the outer spring 70 extends, and the movable contact 44 is not pressed toward the first fixed contact 42 immediately before the first reversal operation. For this reason, when an unintended external force, such as vibration or refrigerant pressure fluctuation, is applied to the pressure-responsive switch 100, the movable contact 44 is likely to be displaced in the vertical direction Z, making it likely to cause a chattering phenomenon in which the movable contact 44 repeatedly comes into contact with and separates from the first fixed contact 42 and the second fixed contact 43.

[0039] In contrast, in this embodiment, as described above, the hole 90 is provided in the inner spring 60, and the rigidity of the inner spring 60 decreases from the side where the abutment portion 63 is located toward the front side X1 where the first connecting portion A is located. Therefore, as shown in FIG. 6(A), when the lower end of the operating shaft 20 moving toward the lower side Z1 is located at the first reversal position γ1, the front side X1 portion of the inner spring 60 is bent so as to curve toward the upper side Z2 from the portion where the hole 90 is formed. In this embodiment, the state in which the inner spring 60 is bent and deformed in this manner is called the deformed state. By the inner spring 60 being in the deformed state, the position of the first connecting portion A is located on the upper side Z2 compared to the conventional microswitch 200 described above, and the inclination of the reversal spring 80 in which the position of the first connecting portion A is higher than the position of the second connecting portion B can be maintained until just before the first reversal operation occurs.

[0040] Therefore, the outer spring 70 is biased toward the lower side Z1 and the front side X1 by the reversing spring load P1, and the movable contact 44 can be maintained in a state in which it is pressed toward the first fixed contact 42 by the contact load P2 toward the lower side Z1. In this embodiment, the first connecting portion A and the second connecting portion B of the reversing spring 80 are located at the same position in the height direction Z when the movable contact 44 leaves the first fixed contact 42 (the second fixed contact 43) and moves toward the second fixed contact 43 (the first fixed contact 42). In this way, until just before the first reversing operation occurs, the reversing spring 80 generates a biasing force that maintains the state in which the outer spring 70 presses the movable contact 44 toward the first fixed contact 42. Therefore, even just before the first reversing operation, the state in which the movable contact 44 is pressed toward the first fixed contact 42 is maintained. As a result, when an unintended external force such as vibration or refrigerant pressure fluctuation is applied to the pressure-responsive switch 100, the chattering phenomenon in which the movable contact 44 repeatedly comes into contact with and separates from the first fixed contact 42 and the second fixed contact 43 is less likely to occur.

[0041] The inner spring 60 is also in a deformed state immediately before the second reversal operation occurs. That is, the inner spring 60 is in a deformed state when the lower end of the operating shaft 20 moving toward the upper side Z2 is in the second reversal position. This allows the inclination of the reversal spring 80, in which the position of the first connecting part A is lower than the position of the second connecting part B, to be maintained until immediately before the second reversal operation occurs, and the state in which the movable contact 44 is pressed toward the second fixed contact 43 is maintained until immediately before the second reversal operation occurs.

[0042] As described above, according to the embodiment described above, the hole 90 (rigidity reducing means) is provided in the inner spring 60 (operating spring), so that the inner spring 60 can be deformed when the operating shaft 20 is located at the first reversal position γ1 (reversal position), that is, immediately before the first reversal operation (reversal operation) occurs. Then, by the inner spring 60 being in the deformed state, the reversing spring 80 can generate a biasing force that maintains the state in which the outer spring 70 (operating spring) presses the movable contact 44 against the first fixed contact 42 (fixed contact). Therefore, even immediately before the first reversal operation, the state in which the movable contact 44 is pressed against the first fixed contact 42 can be reliably maintained, and even if an unintended external force such as vibration or pressure fluctuation occurs, chattering phenomena and the like can be suppressed. Therefore, it is possible to provide a microswitch 1 that can stably maintain the conductive state of the contact 40.

[0043] Furthermore, according to this embodiment, by providing the first reversal position γ1 and the second reversal position, the present invention can also be applied to a type of microswitch 1 in which the first reversal position γ1 (reversal position) at which a first reversal operation (reversal operation) occurs in which the conductive destination of the movable contact 44 switches from the first fixed contact 42 to the second fixed contact 43, and the second reversal position (reversal position) at which the conductive destination of the movable contact 44 switches from the second fixed contact 43 to the first fixed contact 42 are different, and the movable contact 44 can be maintained in a state pressed toward the fixed contact 41 immediately before the reversal operation.

[0044] In addition, according to this embodiment, the hole 90 reduces the rigidity of the inner spring 60 toward the side where the first connecting portion A (connecting portion) is located, so that the side where the first connecting portion A of the inner spring 60 is located can be more easily deformed than the side where the operating shaft 20 of the inner spring 60 is located. This makes it easier to maintain the deformed state of the inner spring 60 on the first connecting portion A side. Therefore, immediately before the reversing operation, it is easier to maintain the biasing force of the reversing spring 80 against the outer spring 70, and the state in which the outer spring 70 presses the movable contact 44 toward the fixed contact 41 can be stably maintained. In addition, according to this configuration, it is easier to increase the rigidity of the inner spring 60 on the side where the operating shaft 20 is located, so that the durability of the inner spring 60 on the side where the operating shaft 20 is located can be improved.

[0045] Furthermore, according to this embodiment, the microswitch 1 can be provided with a rigidity reducing means by the simple method of forming the hole 90 in the inner spring 60.

[0046] Furthermore, according to this embodiment, by increasing the dimension of the hole 90 in the left-right direction Y toward the first connecting portion A, the volume of the inner spring 60 can be made smaller toward the first connecting portion A side and larger toward the abutment portion 63 side. Therefore, the rigidity of the inner spring 60 can be decreased toward the first connecting portion A side, and the side of the inner spring 60 where the first connecting portion A is located can be made more easily deformed than the side of the inner spring 60 where the operating shaft 20 is located. This makes it easier to maintain the deformed state of the inner spring 60 on the first connecting portion A side.

[0047] Furthermore, according to this embodiment, the pressure responsive switch 100 can be constructed by mounting the microswitch 1 capable of stably maintaining the conductive state of the contacts 40.

[0048] Next, a modified example of the microswitch 1 will be described. FIG. 7 is a plan view showing a part of the switching means 50′ in the modified example. The modified example differs from the above-mentioned embodiment in that the narrow portion 64 does not have a hole 90 formed therein. The narrow portion 64 has cutouts 91 formed in both edges in the left-right direction Y (width direction) by cutting the narrow portion 64 in the left-right direction Y. The cutouts 91 have a tapered shape that inclines so as to be positioned inward in the left-right direction Y toward the rear side X2, and the formation of the cutouts 91 reduces the width dimension of the narrow portion 64 in the left-right direction Y toward the rear side X2. With this configuration, the rigidity of the inner spring 60 is reduced particularly in the portion on the front side X1 relative to the wide portion 61. That is, the cutouts 91 constitute the rigidity reducing means in the modified example. According to this modified example, the same action and effect as the above-mentioned embodiment can be achieved. Furthermore, according to this configuration, the rigidity reducing means can be provided in the microswitch 1 by a simple method of cutting the inner spring 60 to form the cutouts 91.

[0049] The above-described embodiments merely show typical forms of the present invention, and the present invention is not limited to these. In other words, the present invention can be implemented with various modifications within the scope of the gist of the present invention. As long as the configuration of the microswitch 1 of the present invention is included in such modifications, they are of course included in the scope of the present invention. For example, in the description of the present embodiment, the microswitch 1 is described as being used when detecting abnormally high pressure, but conversely, the microswitch 1 can also be used when detecting abnormally low pressure. In addition, in the initial state, the lever 17 is inclined so as to be located on the upper side Z2 as it moves from the rear end supported by the rotating shaft 16 toward the front end. Conversely, the state after rotation in this embodiment may be set as the initial state of the lever 17, the other side b in this embodiment may be set as the one side a, and the operating direction of the operating shaft 20 and the switching means 50 may be adjusted accordingly to construct the microswitch 1.

[0050] Furthermore, the microswitch 1 can be mounted on various switches other than pressure switches in which the lever 17 rotates when some external force is applied. For example, although the pressure responsive switch 100 of this embodiment has been described mainly as being used as a pressure switch, the pressure responsive switch 100 can also be used as a temperature switch. That is, in this embodiment, the use of the pressure responsive switch 100 has been described as an example in which the fluid to be detected (here, the refrigerant circulating in the refrigeration cycle) is introduced through the joint tube 117, and the pressure of the detection target is applied directly to a sensitive member such as a bellows or a diaphragm to detect a pressure change, but the use of the pressure responsive switch 100 is not limited to this.

[0051] That is, a temperature switch can be configured by connecting a temperature sensing barrel to the element 116 in the pressure responsive switch 100 of this embodiment via a capillary, and filling a closed space formed by the sensing member, the capillary, and the temperature sensing barrel with a refrigerant. In this way, in a temperature switch using the pressure responsive switch 100 of this embodiment, the sensing member deforms or displaces in the forward and backward directions X in response to the pressure inside the closed space that changes due to the temperature change detected by the temperature sensing barrel, and the force at that time is transmitted to the lever 17 to change the conductive state of the contact 40. In this embodiment, the microswitch 1 is provided with a pair of levers 17, and the corresponding operating shafts 20, contacts 40, switching means 50, etc., to configure a so-called dual type microswitch 1, but the present invention can be applied to various microswitches other than the dual type microswitch 1.

[0052] In this embodiment, the plate-shaped inner spring 60 is used as the operating spring, and the plate-shaped outer spring 70 is used as the action spring. However, the structure of the operating spring and the action spring is not limited to this. For example, the operating spring and the action spring may be configured using a spring member that is not formed in a plate shape. [Explanation of symbols]

[0053] Z Vertical direction (forward / backward direction) γ Inversion position 1 Microswitch 20 Working shaft 41 Fixed contact 42 First fixed contact (one of a pair of fixed contacts) 43 Second fixed contact (the other of the pair of fixed contacts) 44 Movable contact 50 Switching Method 60 Inner spring (operating spring) 70 External spring (working spring) 80 Reversing spring 90 Hole (rigidity reduction means)

Claims

1. A microswitch comprising: a movable contact provided between a pair of fixed contacts; an operating shaft that moves in an advancing / retreating direction; and a switching means that performs a reversing operation in association with the movement of the operating shaft to electrically connect the movable contact to one or the other of the pair of fixed contacts, The switching means includes an operating spring connected to the operating shaft, an action spring that holds the movable contact, and a reversing spring that connects the operating spring and the action spring, The operating spring is provided so as to be deformable in association with the movement of the operating shaft, The reversing spring is provided so as to be able to bias the application spring in response to deformation of the operating spring, the action spring is biased by the reversing spring to press the movable contact toward one or the other of the pair of fixed contacts, The movement range of the operating shaft includes a reversal position through which the reversal motion occurs, the operating spring is provided with a stiffness reducing means for being in a deflected deformed state when the operating shaft is located at the reversal position, A microswitch characterized in that, when the operating spring is in the deformed state, a spring force is generated by the reversing spring to maintain the acting spring pressing the movable contact toward one or the other of the pair of fixed contacts.

2. The fixed contact includes a first fixed contact and a second fixed contact disposed on a retreat side in the advance / retract direction relative to the first fixed contact, the reversal positions include a first reversal position where the reversal motion occurs after the operating shaft passes toward the forward side in the forward / reverse direction, and a second reversal position where the reversal motion occurs after the operating shaft passes toward the backward side, 2. The microswitch according to claim 1, wherein when the operating shaft moving toward the forward side is located at the first reversal position, the movable contact is pressed toward the first fixed contact, and when the operating shaft moving toward the backward side is located at the second reversal position, the movable contact is pressed toward the second fixed contact.

3. The switching means includes an inner spring as the operating spring formed in a plate shape extending in a direction intersecting the forward / reverse direction, an outer spring as the action spring formed in a plate shape surrounding the inner spring, and the reversing spring, The inner spring includes a contact portion that contacts the operating shaft, 3. The microswitch according to claim 1, wherein the stiffness reducing means reduces stiffness of the inner spring from the side where the abutting portion is located toward the side where the connection portion with the reversing spring is located.

4. 4. The microswitch according to claim 3, wherein the stiffness reducing means is a hole penetrating the inner spring in a thickness direction.

5. 5. The microswitch according to claim 4, wherein the width of the hole increases toward the connecting portion.

6. 4. The microswitch according to claim 3, wherein the stiffness reducing means is formed by cutting the inner spring in a width direction.

7. A pressure responsive switch comprising the microswitch according to claim 1.

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