Patent Application
20170133168
This application claims priority to Japanese Patent Application No. 2015-218921 filed Nov. 6, 2015, the entire contents of which are incorporated herein by reference.
The present invention relates to a switch.
Conventionally, regarding switches for opening and closing contacts according to the movement of a plunger, switches that are provided with a coil spring for returning the plunger are known. For example, JP 2013-541145A discloses an emergency stop switch that is provided with a coil spring on a lower side in a direction in which the plunger moves.
JP 2013-541145A (published on Nov. 7, 2013) is an example of background art.
Here, in normally-open switches, in which a fixed contact provided on a housing side of the switch and a movable contact provided on a plunger side come into contact with each other when the switch is operated, the contacts need to be brought into contact with each other at a predetermined pressure, in order to achieve reliable contact between the contacts. However, in the switch disclosed in JP 2013-541145A, since the coil spring is compressed according to the movement of the plunger, the amount of compression of the coil spring increases with an increase in the amount of movement of the plunger, resulting in an increase in a biasing force acting on the plunger. Thus, there is the problem that a large load is required to bring the contacts into contact with each other at a predetermined pressure, and the operability of the switch deteriorates.
In order to bring the contacts into contact with each other at a predetermined pressure with a small load, it is conceivable to use a spring that has a small spring constant. However, when the spring that has a small spring constant is used, there is a risk that the contacts will be likely to come into contact with each other due to vibration from the outside or the like, and the switch will malfunction.
The present invention was made in view of the above-described problems, and it is an object thereof to provide a switch that can reliably bring contacts into contact with each other with a small load, and can be prevented from malfunctioning.
In order to solve the above-described problems, according to the present invention, a switch is provided with a plunger configured to linearly move from a reference position to an operation position in response to an operation performed on an operation portion, and is configured to open and close contacts according to the movement of the plunger, the switch including: a fixed contact; a movable contact that is configured to move together with the plunger, is in contact with the fixed contact in the operation position, and is not in contact with the fixed contact in the reference position; a return spring configured to bias the plunger in a returning direction from the operation position to the reference position; and a contact pressure spring that abuts against the plunger, and in which a biasing direction changes according to movement of the plunger, wherein the contact pressure spring biases the plunger in an opposite direction to the returning direction when the plunger is in the operation position, and biases the plunger in a direction different from the opposite direction to the returning direction when the plunger is located at a position between the reference position and a predetermined position, the predetermined position being located between the reference position and the operation position. Here, “reference position” refers to a position of the plunger in a state in which no operation is performed on the operation portion, and “operation position” refers to a position of the plunger in a state in which the amount of operation of the operation portion is the greatest.
According to the foregoing configuration, since the contact pressure spring biases the plunger in a direction different from the opposite direction to the returning direction when the plunger is located at a position between the reference position and the predetermined position, it is necessary to move the plunger against the biasing force of the return spring between the reference position to the predetermined position. Accordingly, the contacts do not come into contact with each other due to vibration from the outside or the like, making it possible to prevent a malfunction. Also, in the operation position, the contact pressure spring biases the plunger in the opposite direction to the returning direction, and thus it is possible to reliably place the contacts in contact with each other with a small load.
Furthermore, preferably, the switch according to the present invention is such that the contact pressure spring abuts against a surface perpendicular to the returning direction when the plunger is in the operation position, and abuts against a side surface of the plunger when the plunger is located at a position between the reference position and the predetermined position.
According to the foregoing configuration, it is possible to easily change the direction in which the contact pressure spring biases the plunger.
Furthermore, preferably, the switch according to the present invention is such that the contact pressure spring is a torsion spring.
Furthermore, preferably, the switch according to the present invention further includes a mechanism for moving, in response to the operation performed on the operation portion, the plunger to the operation position with a load that is unrelated to an operation load applied to the operation portion.
According to the foregoing configuration, it is possible to provide a switch that can include a simple configuration mechanism for moving the plunger to the operation position.
According to the present invention, it is possible to provide a switch that can reliably bring contacts into contact with each other with a small load, and can be prevented from malfunctioning.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The operation portion 10 is a member for accepting an operation performed by an operator, and is provided so as to be able to perform a press-in operation performed on the main body portion 20. Note that the present embodiment will describe a press button switch for accepting a press-in operation performed by an operator, but the present invention is not limited to this. For example, the switch 1 may be provided with a cam mechanism for converting a rotational operation into a press-in operation, and the operation portion 10 may be configured to accept a rotational operation performed by an operator.
The switch 1 is a normally-open switch, in which contacts come into contact with each other when the switch is operated. As shown in
The housing 25 is box-shaped, and holds, in the inside thereof the constituent components of the main body portion 20. Furthermore, the housing 25 has a hole 25b in the center of an upper surface 25a thereof.
The plunger 30 has, between the upper end portion 31 and the hanging portion 32 of in the direction in which the plunger 30 moves, two holes 33, an upper coil spring supporting portion 34, and a lower coil spring supporting portion 35. The two holes 33, the upper coil spring supporting portion 34, and the lower coil spring supporting portion 35 are each a through-hole that extends in a direction perpendicular to the vertical direction in which the plunger 30 moves.
The upper coil spring supporting portion 34 and the lower coil spring supporting portion 35 are formed in the central part in the width direction of the plunger 30, and have substantially the same shape. Furthermore, the upper coil spring supporting portion 34 is formed on the upper side in the direction in which the plunger 30 moves, and the lower coil spring supporting portion 35 is formed on the lower side in the direction in which the plunger 30 moves.
The two holes 33 are respectively formed on the outer sides of the upper coil spring supporting portion 34 formed in the central part. Each hole 33 has two openings 33a and 33b of different sizes, and the opening 33a has a larger length in the direction in which the plunger 30 moves than that of the opening 33b. The hole 33 has, between an upper surface 33d and the opening 33a, an inclined surface 33c that is inclined upward from the opening 33b side to the opening 33a. Furthermore, the two holes 33 are formed so as to be symmetric with respect to an axis L that passes through a central portion 30a (see
The upper coil spring 65 is arranged in the upper coil spring supporting portion 34 of the plunger 30. Similarly, the lower coil spring 66 is arranged in the lower coil spring supporting portion 35 of the plunger 30.
The terminals 40a to 40d are press-in type terminals, and are electrically connected to external devices as a result of cords or the like being inserted through insertion ports 41 provided in the housing 25. The switch 1 according to the present embodiment is a two-stage switch in which the pair of terminals 40a and 40b are provided on the upper side, and the pair of terminals 40c and 40d are provided on the lower side.
The housing-side contacts 60a to 60d are respectively electrically connected to the corresponding terminals 40a to 40d. Specifically, the housing-side contact 60a is connected to the terminal 40a, the housing-side contact 60b is connected to the terminal 40b, the housing-side contact 60c is connected to the terminal 40c, and the housing-side contact 60d is connected to the terminal 40d. That is, the pair of housing-side contacts 60a and 60b are provided on the upper side, and the pair of housing-side contacts 60c and 60d are provided on the lower side.
The upper contact-supporting member 56 is inserted through the upper coil spring supporting portion 34. Furthermore, the upper contact-supporting member 56 is fixed to the upper coil spring 65, and operates together with the upper coil spring 65, that is, the plunger 30. Similarly, the lower contact-supporting member 57 is inserted through the lower coil spring supporting portion 35. Furthermore, the lower coil spring supporting portion 35 is fixed to the lower coil spring 66, and operates together with the lower coil spring 66, that is, the plunger 30.
The upper contact-supporting member 56 is provided with a pair of plunger-side contacts 55a and 55b. Furthermore, the lower contact-supporting member 57 is provided with a pair of plunger-side contacts 55c and 55d. Accordingly, the plunger-side contacts (movable contacts) 55a to 55d move together with the plunger 30. Note that the plunger-side contact 55a and the plunger-side contact 55b are provided at positions that are symmetric with respect to the axis L, and the plunger-side contact 55c and the plunger-side contact 55d are provided at positions that are symmetric with respect to the axis L. That is, the axis L is an axis that is parallel to the direction in which the plunger 30 moves, and passes through the midpoint between the plunger-side contact 55a and the plunger-side contact 55b, and the midpoint between the plunger-side contact 55c and the plunger-side contact 55d.
The plunger-side contacts 55a to 55d are respectively provided at positions at which they are opposed to the corresponding housing-side contacts 60a to 60d, and, in the reference position shown in
Furthermore, the plunger-side contact 55a and the plunger-side contact 55b are electrically connected to each other, and the plunger-side contact 55c and the plunger-side contact 55d are electrically connected to each other.
The two upper torsion springs 45 are springs for biasing the plunger 30 in a returning direction from the operation position to the reference position. The two upper torsion springs 45 are respectively arranged on one side and the other side of a plane Q, which is defined as a plane that includes the axis L passing through the central portion 30a of the plunger 30, and is perpendicular to perpendicular lines M connecting the plunger-side contacts (movable contacts) 55a to 55d and the axis L. That is, the upper torsion spring (first torsion spring) 45a is arranged on one side of the plane Q, and the upper torsion spring (second torsion spring) 45b is arranged on the other side of the plane Q.
Furthermore, the two upper torsion springs 45 are arranged at positions that are symmetric with respect to the axis L, similar to the above-described two holes 33. Since the two upper torsion springs 45 are arranged at positions symmetric with respect to the axis L of the plunger 30 in this way, it is possible for a biasing force to act on the plunger 30 uniformly. Note that the plane Q is, in other words, a plane that is perpendicular to a straight line connecting the plunger-side contact 55a and the plunger-side contact 55b, and to a straight line connecting the plunger-side contact 55c and the plunger-side contact 55d.
The upper torsion springs 45 include a coil wire portion 46, a first arm 47 that extends from one end of the coil wire portion 46 to the plunger 30 and abuts against the plunger 30, and a second arm 48 that extends from the other end of the coil wire portion 46. The upper torsion springs 45 are supported by columnar spring holding portions 25c provided in the housing 25 being respectively arranged in hollow parts of the coil wire portions 46. Furthermore, the second arms 48 of the upper torsion springs 45 are respectively fixed by locking portions 25d provided on the housing 25. As shown in
Here, the first arm 47 of the upper torsion spring 45a and the first arm 47 of the upper torsion spring 45b are arranged so as to be symmetric with respect to the axis L. As a result of in addition to the two upper torsion springs 45 being arranged at positions symmetric with respect to the axis L of the plunger 30, the first arms 47 of the upper torsion springs 45 being provided so as to be symmetric with respect to the axis L, a biasing force acts on the plunger 30 more uniformly.
Note that, as shown in
In the reference position shown in
The lower torsion spring 50 is a spring in which the biasing direction changes according to the movement of the plunger. The lower torsion spring 50 includes a coil wire portion 51, a first arm 52 that extends from one end of the coil wire portion 51, and a second arm 53 that extends from the other end of the coil wire portion 51. The lower torsion spring 50 is supported by a columnar spring holding portion 25e provided on the housing 25 being arranged in a hollow part of the coil wire portion 51. The second arm 53 of the lower torsion spring 50 is fixed by a locking portion 25f provided on the housing 25.
In the reference position shown in
The following will describe operation of the main body portion 20 when an operator performs an operation performed on the operation portion 10 of the switch 1.
As shown in
When an operation is performed on the operation portion 10, and the plunger 30 is pressed against the biasing force of the upper torsion springs 45, the upper contact-supporting member 56 and the lower contact-supporting member 57, which operate together with the plunger 30, also move downward. Accordingly, the respective distances between the plunger-side contacts 55a to 55d and the housing-side contacts 60a to 60d decrease, and the plunger-side contacts 55a to 55d and the housing-side contacts 60a to 60d are brought into contact with each other when the plunger 30 is pressed by a predetermined amount (see
Here, each upper torsion spring 45 is provided with the bent portion 47a-1 in the front end portion 47a of the first arm 47, and the bent portion 47a-1 abuts against the plunger 30 when no operation is performed. Accordingly, the place at which the upper torsion spring 45 abuts against the plunger 30 is located on a curved surface. Accordingly, the upper torsion springs 45 do not get caught when the plunger 30 is pressed. This makes it possible to perform the operation of the switch 1 smoothly, and to improve the operability and durability.
Then, the upper torsion spring 45 slides on the upper surface 33d, located on the side in the returning direction of the plunger 30, of the hole 33 according to the downward movement of the plunger 30. Accordingly, the first arm 47 of the upper torsion spring 45 is also rotated downward. Accordingly, as shown in
When the plunger 30 is further pressed down from the state shown in
Accordingly, since the region P in which the upper torsion spring 45 abuts against the plunger 30 moves, the load necessary for pressing down the plunger 30 for the same length changes. That is, the load necessary for pressing down the plunger 30 changes according to the length from the coil wire portion 46 of the upper torsion spring 45 to the region P in which the upper torsion spring 45 abuts against the plunger 30, and the angle of rotation of the first arm 47 from the reference position. Note that during the movement of the plunger from the reference position to the operation position, the angle by which the first arm of the upper torsion spring 45 is rotated is preferably in a range from 120° to 220°.
Here, a case is considered in which no inclined surface 33c is provided in the holes 33 of the plunger 30. In such a case, when the angle of rotation of the first arm 47 of each upper torsion spring 45 increases, and the first arm 47 is rotated downward from being horizontal, the region P in which the upper torsion spring 45 abuts against the plunger 30 moves to the opening 33a of the hole 33. Accordingly, the length from the coil wire portion 46 of the upper torsion spring 45 to the region P in which the upper torsion spring 45 abuts against the plunger 30 drastically changes, and the load necessary for pressing down the plunger 30 drastically increases when the first arm 47 is rotated beyond being horizontal, resulting in deterioration of the operability of the switch 1.
In contrast, in the switch 1 according to the present embodiment, each hole 33 of the plunger 30 has the inclined surface 33c on the upper surface 33d of the opening 33a on the side into which the first arm 47 of the corresponding upper torsion spring 45 is inserted. Accordingly, even if the first arm 47 is rotated downward from the horizon, the region P in which the upper torsion spring 45 abuts against the plunger 30 is located at the boundary between the upper surface 33d and the inclined surface 33c of the hole 33. Accordingly, it is possible to reduce the change in length from the coil wire portion 46 of the upper torsion spring 45 to the region P in which the upper torsion spring 45 abuts against the plunger 30, and to provide a switch 1 with excellent operability.
Furthermore, in the reference position as shown in
Furthermore, the switch 1 according to the present embodiment is provided with two upper torsion springs 45, namely, the upper torsion spring 45a arranged on one side of the plane Q and the upper torsion spring 45b arranged on the other side of the plane Q. Here, in order to downsize a switch provided with torsion springs, it is conceivable to use short-armed torsion springs. However, the angle of rotation of the arms, which corresponds to the amount of movement of the plunger 30, is larger when using short-armed torsion springs than when using long-armed torsion springs. Accordingly, the positions at which the torsion springs are in contact with the plunger 30 largely change depending on the movement of the plunger, causing the problem that a biasing force does not act on the plunger 30 in a balanced manner.
However, since the switch 1 according to the present embodiment includes two upper torsion springs 45, namely, the upper torsion spring 45a arranged on one side of the plane Q and the upper torsion spring 45b arranged on the other side of the plane Q, it is possible for a biasing force to act on the plunger 30 in a balanced manner even if short-armed torsion springs are used and the positions at which the torsion springs are in contact with the plunger are largely changed depending on the movement of the plunger 30. Therefore, it is possible to use short-armed upper torsion springs 45, which generates space for arranging another member of the switch 1, and makes it possible to downsize the switch 1.
Moreover, in the reference position as shown in
Furthermore, in the state shown in
As shown in
That is, in the state shown in
When the plunger 30 is further pressed down from the state shown in
When the plunger 30 is further pressed down from the state shown in
As shown in
In contrast, the switch 1 according to the present embodiment is provided with the lower torsion spring 50 that applies a biasing force to the plunger 30, and the plunger 30 that includes the hanging portion 32 in the shaped such that the direction of the biasing force of the lower torsion spring 50 is changed. When the plunger 30 is located at a position between the reference position and a predetermined position, which is located between the reference position and the operation position, the lower torsion spring 50 biases the plunger 30 in a direction different from the opposite direction to the returning direction. Accordingly, as shown in
Also, when the plunger 30 is pressed down to the predetermined position, the load is reduced because the biasing direction of the lower torsion spring 50 is changed to the opposite direction to the returning direction. Accordingly, in the operation position, it is possible to bring the plunger-side contacts 55a to 55d into contact with the housing-side contacts 60a to 60d at a predetermined pressure with a smaller load than in the case where no lower torsion spring 50 is provided.
Here, as an example, a case is considered in which the switch 1 is used as an emergency stop switch. Emergency stop switches ordinarily have a mechanism that can press down the plunger 30 in response to a press-in operation performed on the operation portion 10 by an operator, irrespective of the operation load of the operator. This mechanism needs to apply a larger force to the plunger 30 than the biasing force of the spring that biases the plunger 30 in the returning direction, in order to reliably activate the emergency stop switch. The mechanism for pressing down the plunger 30 is not particularly limited, but a mechanism can be used in which, for example, an engaged compression member is provided, and as a result of being disengaged by an operation performed on the operation portion 10, the compression member compresses the plunger 30 at a predetermined pressure with a load that is unrelated to the operation load applied to the operation portion 10 by the operator.
Here, as shown in
On the other hand, as shown in
At a result of the upper surfaces 33e of the holes 33 being inclined in this way, the first arms 47 of the upper torsion springs 45 are unlikely to get caught on the plunger 30 when the plunger 30 is pressed down, making it possible to improve the operability and durability of the switch 1.
Furthermore, the present embodiment has described an example in which the lower torsion spring 50, which is a torsion spring, is provided as a spring that changes the direction of a biasing force according to the amount of press of the switch 1. However, the spring only needs to change the direction in which a biasing force acts according to the amount of press of the switch 1, and thus a blade spring 70, as shown in
Furthermore, the present embodiment has described a configuration in which the first arm 47 of each upper torsion spring 45 is provided with, at the front end thereof, the bent portion 47a-1, and the place at which the upper torsion spring 45 abuts against the plunger 30 is located on a curved surface, in order to prevent the first arm 47 from getting caught on the plunger 30 when the plunger 30 moves from the reference position. However, it is sufficient that the first arm 47 of the upper torsion spring 45 does not get caught on the plunger 30 when the plunger 30 moves from the reference position. For example, as shown in
Note that the present embodiment has described an example in which the terminals 40a to 40d are press-in type terminals, but the present invention is not limited to them. That is, the terminals 40a to 40d may be screw-type terminals.
Furthermore, the present embodiment has described an example in which the upper coil spring 65 and the lower coil spring 66 are arranged inside the plunger 30, and the upper contact-supporting member 56 is fixed to the upper coil spring 65, and the lower contact-supporting member 57 is fixed to the lower coil spring 66. However, the switch 1 does not necessarily include the upper coil spring 65 and the lower coil spring 66, and the upper contact-supporting member 56 and the lower contact-supporting member 57 may be fixed to the plunger 30, or may be formed in one piece with the plunger 30.
Furthermore, the present embodiment has described the switch 1 that includes the four terminals 40a to 40d, and is provided with the pair of housing-side contacts 60a and 60b and the pair of plunger-side contacts 55a and 55b on the upper side, and the pair of housing-side contacts 60c and 60d and the pair of plunger-side contacts 55c and 55d on the lower side. However, the configuration of the switch 1 is not limited to this. For example, the switch 1 may be a one-stage switch that includes two terminals for connecting to the outside. Furthermore, a pair of housing-side contacts and a pair of plunger-side contacts do not necessarily provided on each of the upper and lower sides, but a configuration is also possible in which a single housing-side contact and a single plunger-side contact may be provided on each of the upper and lower sides. Even in such a case, the plane Q may be a plane that is perpendicular to a perpendicular line M connecting the plunger-side contact to the axis L of the plunger 30, and includes the axis L.
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims, and the technical scope of the present invention also encompasses embodiments that can be obtained by appropriately combining the technical means disclosed in the different embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-218921 | Nov 2015 | JP | national |
