JPH11283466A - Limit switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a limit switch capable of enlarging the rotation angle of an actuator and a linear stroke of a plunger. SOLUTION: This limit switch comprises: a rotation shaft 1; an actuator 2 which abuts against a member to be detected and rotates in either side direction from an initial position around the rotation shaft 1; a conversion cam 3 having a rotation center 31 and an peripheral part 32 which converts into linear movement by rotating from a prescribed position 32a on the peripheral part 32 corresponding to an initial rotational position of the conversion cam 32 in an either direction of the peripheral part 32; a plunger 5 which moves linearly with its one end part 51 abutting against the peripheral part 32 of the conversion cam 3; and a switch part 6 whose movable contact comes in contact with and gets off a fixed contact by being driven by the plunger 5. The distance δ between the rotation center 31 and the peripheral part 32 of the conversion cam 3 is designed so as to become larger with increasing distance of a position on the peripheral part 32 from the prescribed position 32a on the peripheral part 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a limit switch which is used in a production facility or an industrial machine and in which an actuator abuts on a detection body and detects the detection body.

[0002]

2. Description of the Related Art Conventionally, as a conventional example of this type of limit switch, there is one having a configuration shown in FIGS. This includes a rotating shaft A, an actuator B supported on the rotating shaft A and abutting against the detection body and rotating from the initial position to both sides around the rotating shaft A, a rotation center C1 and an outer periphery. The outer peripheral portion C2 is formed in a substantially circular shape having a portion C2, and the outer peripheral portion C2 corresponds to a predetermined outer peripheral portion position C corresponding to the initial position of the actuator B.
A conversion cam C which rotates from 21 to both sides of the outer periphery to convert to a linear operation; a plunger D which linearly operates by one end D1 abutting against an outer peripheral portion C2 of the conversion cam C via a rotating body D2; And a switch section E driven by D to move the movable contact to and away from the fixed contact.

More specifically, the conversion cam C has a concave portion C3 provided at a predetermined outer peripheral position C21, and the plunger D has a rotating body D2 formed of a steel ball provided at a position corresponding to the concave portion C3. Rotate by the rotation of. Here, the distance between the rotation center C1 and the outer peripheral portion C2 of the conversion cam C is the same except for the concave portion C3. Further, a coil-shaped return spring F is provided on the conversion cam C to apply a return force to the actuator B to return the actuator B to the initial position.

In the switch section E, a fixed contact and a movable contact may be welded to each other, and a forced opening mechanism for forcibly opening the movable contact welded to the fixed contact by a plunger D is provided. It is desired to be built in.

The operation of this conventional example will be described. When the detection body comes into contact with the actuator B, the actuator B rotates from the initial position, and the rotation is converted into a linear motion by the conversion cam C to linearly move the plunger in one direction. , The movable contact is brought into contact with or separated from the fixed contact, and the switching operation is performed on or off.

As another conventional example of this type of limit switch, there is one having a configuration shown in FIGS.
In another conventional example, functions different from those of the above-described conventional example will be described. Members having substantially the same functions as those of the conventional example will be denoted by the same reference numerals and description thereof will be omitted.

The conversion cam C is not provided, and the rotation axis A
Represents a D-shaped D-cut portion A1 having a plunger D
As shown in FIG. 13, the plunger D abuts on one end D1 of the plunger D, and when rotated, directly moves the plunger D linearly in one direction. A return spring F is provided on the plunger D to push up the plunger in the other direction and to apply a rotational moment to the D-cut portion A1 to return the actuator B to the initial position.

[0008]

In the conventional limit switch described above, the actuator B can take a large angle of rotation from the initial position and can rotate more than 90 degrees on one side, so that the user can use it. Adjustment can be easily performed.

However, the linear stroke of the plunger D is determined by the depth of the concave portion C3 formed in the conversion cam C. Even if the rotation angle of the actuator B is increased, only a small linear stroke is performed. Therefore, the switch section E cannot incorporate a forced opening mechanism in which the plunger D requires a large linear stroke.

On the other hand, in another conventional limit switch, the linear stroke of the plunger D can be increased by changing the depth of the D cut portion A1. However, when the rotation angle of the actuator B is increased, the rotation moment is reduced, and a reset failure may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a limit switch capable of increasing both the rotation angle of an actuator and the linear stroke of a plunger.

[0012]

According to a first aspect of the present invention, there is provided a rotating shaft, which is supported by the rotating shaft and abuts on a detection body to rotate from an initial position. An actuator that rotates to both sides around an axis, and a conversion that has a rotation center and an outer circumference, and the outer circumference rotates from a predetermined outer circumference position corresponding to the initial position of the actuator to both outer circumferences to convert to linear motion. A limit switch comprising: a cam; a plunger having one end abutting against an outer peripheral portion of the conversion cam and linearly operating; and a switch unit driven by the plunger to move a movable contact to and away from a fixed contact. The cam is configured such that the outer peripheral portion is formed such that the distance from the rotation center increases as the distance from the predetermined outer peripheral position to both sides of the outer periphery increases.

According to a second aspect of the present invention, in the first aspect, the conversion cam has a concave portion provided at the predetermined outer peripheral portion, and the plunger is rotated by rotation of the outer peripheral portion of the conversion cam. The rotating body is provided at one end, and is formed so as to contact the outer peripheral portion via the rotating body.

According to a third aspect of the present invention, in the first or second aspect, the movable contact welded to the fixed contact is forcibly released by being driven by the plunger. Are provided in the switch section.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a rotating shaft, which is formed of a metal or resin into a rod shape, and has a base end 11 and a tip 12 having a circular cross section formed narrower than the base end 11. A protrusion 13 having a rotation stop is provided on the base end 11 in the axial direction, and a fan-shaped stopper 14 is provided on the base end 11 in a direction perpendicular to the axial direction. Furthermore, a square engaging projection 1
5, and a concave groove 16 for mounting the O-ring 16a are formed substantially in the center.

Reference numeral 2 denotes an actuator, which comprises an arm 21 made of metal or resin and having a locking hole 21a at an end, and a rotating ring 22 made of metal and rotatably supported by the arm 21. You. The arm 21 has a locking hole 21a locked to the protrusion 13 of the rotating shaft 1, is fixed to the rotating shaft 1 so as not to run idle, is supported by the rotating shaft 1, and the rotating ring 22 is connected to the detecting body. (Not shown), and rotates from the initial position 2a to both sides around the rotation shaft 1 at a rotation angle α.

Reference numeral 3 denotes a conversion cam, which is formed of metal or resin in a plate shape having a rotation center 31 and an outer peripheral portion 32, and a predetermined outer peripheral portion position 32 a corresponding to the initial position 2 a of the actuator 2 is formed on the outer peripheral portion 32. A substantially semicircular concave portion 33 is formed at a predetermined outer peripheral portion position 32a. Also,
A first tubular portion 34 having a square engaging recess is protruded to one side, and a second tubular portion 35 cut out in a semicircular cross section is protruded to the other side. Abuts on the cylindrical wall of the second cylindrical portion 35. Then, it is inserted into the head portion 37 together with the return spring 36, and the engagement recess of the first cylindrical portion 34 engages with the engagement protrusion 15 of the rotation shaft 1 and is connected to the rotation shaft 1.

An engaging projection 37a is provided on the protruding cylinder of the head portion 37 and contacts the stopper 14 of the rotating shaft 1 to determine the maximum rotating angle α of the actuator 2. Then, the rotation is made to the both sides of the outer circumference with the predetermined outer circumference position 32a as the center of the outer circumference, that is, from the predetermined outer circumference position 32a to both the outer circumferences, and converted into a linear operation.

Here, as shown in FIG. 1, the distance δ between the outer peripheral portion 32 and the rotation center 31 becomes longer as the outer peripheral portion 32 moves away from the predetermined outer peripheral portion position 32a to both sides of the outer periphery.
1 and the outer peripheral portion 32 have a predetermined outer peripheral portion position 32a.
It is formed so that it becomes longer as it goes to the outer peripheral part 32 which is farther away. Therefore, as compared with the conventional example shown by the two-dot chain line in FIG.
Becomes larger as the outer peripheral portion 32 moves away from the predetermined outer peripheral portion position 32a.

Reference numeral 4 denotes a rotating member, which is a steel ball formed in a spherical shape or a roller formed in a circular cross section. The rotating member is provided in a predetermined outer peripheral position 32a of the conversion cam 3, that is, in the concave portion 33, and rotates.

Reference numeral 5 denotes a plunger, which is made of insulating resin and is formed in a rectangular bottomed cylindrical shape having a cylindrical interior. One end portion 51 and a concave bottom portion 51a provided at the one end portion 51 are respectively provided. The body 4 is provided at the one end 51 while being engaged with the bottom 51 a, and is rotated by the rotation of the outer peripheral portion 32 of the conversion cam 3. Then, the one end 51 abuts on the outer peripheral portion 32 via the rotating body 4 and linearly moves, and slides on the side wall of the body 61 of the switch unit 6 described later.

An OT absorption spring 52 is provided inside the cylinder, and a movable contact 64 to be described later is connected to a normally-open fixed contact 63.
In addition to absorbing the pushing amount of the plunger 5 after the switching operation in contact with b, that is, the so-called OT stroke, the plunger 5 is biased toward the conversion cam 3 side.

Reference numeral 6 denotes a switch, which includes a body 61, an operating shaft 62 driven by the plunger 5, and a body 6.
1 and a normally-closed fixed contact 63a and a normally-open fixed contact 6
3b and a movable contact 64 fixed to a plate-shaped movable contact spring 64a. A movable contact spring 64a protrudes from the operating shaft portion 62 in a direction perpendicular to the central axis of the body 61, and the movable contact 64 is a normally closed fixed contact 63.
a and the normally open fixed contact 63b.
Then, the movable contact 64 is driven by the plunger 5 via the operating shaft portion 62 to come into contact with and separate from the normally closed fixed contact 63a and the normally open fixed contact 63b.

The operation of this will be described. When the rotating ring 22 abuts on the detection body, the actuator 2 rotates from the initial position 2a to both sides around the rotating shaft 1, and the conversion cam 3 moves from the predetermined outer peripheral position 32a where the outer peripheral portion 32 is provided with the concave portion 33. It turns to both sides of the outer periphery to convert the turning operation into a linear operation. The plunger 5 reciprocates linearly with one end 51 abutting on the concave portion 33 of the conversion cam 3 and the outer peripheral portions 32 on both outer peripheral sides of the concave portion 33 via the rotating body 4 provided on the bottom portion 51a.

Here, the rotation angle α of the actuator 2
FIG. 5 shows the relationship between the stroke and the linear stroke of the plunger 5. Since the concave portion 33 is provided at the predetermined outer peripheral portion position 32a of the conversion cam 3, the linear stroke rapidly rises with respect to the rotation angle α. Then, the switch portion 6 causes the operating shaft portion 62 driven by the plunger 5 to linearly operate, presses the movable contact spring 64a and instantaneously reverses it,
The movable contact 64 is changed from the normally closed fixed contact 63a to the normally open fixed contact 6
3b, the switching operation is performed.

Next, the conversion cam 3 is moved to a predetermined outer peripheral position 32.
It rotates to both sides of the outer periphery with respect to a. At this time, the conversion cam 3
Is longer as the distance δ from the center of rotation 31 becomes farther away from the predetermined outer peripheral position 32a toward both sides of the outer periphery, so that the plunger 5 is rotated by the outer peripheral part 32 whose one end 51 is separated from the predetermined outer peripheral position 32a. 4, the one end 5
The distance δ between 1 and the rotation center 31 increases, and the linear stroke of the plunger 5 increases. As shown in FIG. 5, the maximum straight stroke is about 2 mm in the conventional example (b).
However, in the present invention (a), the maximum is 4 mm to 4.5 mm.
This is about twice the conventional example.

Next, when the detection body is separated from the rotary ring 22 of the actuator 2, the actuator 2 is returned to the initial position 2a by the return spring 36, and the conversion cam 3 is positioned at a predetermined outer peripheral portion 32a at one end 51 of the plunger 5. The movable contact spring 64a is reversed, and the movable contact 64 is switched to the normally open fixed contact 63.
b contacts the normally closed fixed contact 63a.

In the limit switch according to the first embodiment, as described above, the outer peripheral portion 32 is
The conversion cam 3 is formed so that the distance δ from the predetermined outer peripheral position 32a becomes longer as the distance from the predetermined outer peripheral position 32a to both sides of the outer circumference, so that one end 51 of the plunger 5 is separated from the predetermined outer peripheral position 32a. 32, the distance δ between the one end 51 and the rotation center 31 of the conversion cam 3 increases, so that the linear stroke of the plunger 5 can be increased and the rotation angle α of the actuator 2 can be increased. hand,
Adjustment at the time of installation can be easily performed, and breakage can be prevented even if the detection body shakes greatly in a state of contact.

Further, a concave portion 33 is provided at a predetermined outer peripheral portion position 32 a of the conversion cam 3, and the plunger 5 is rotated by the rotation of the outer peripheral portion 32 of the conversion cam 3.
Is provided at one end portion 51, and the outer peripheral portion 32 is
, The linear stroke of the plunger 5 rises sharply with respect to the rotation angle α of the actuator 2, and the switching operation in which the movable contact 64 contacts the normally closed fixed contact 63a to the normally open fixed contact 63b is accelerated. In addition to this, the friction between the outer peripheral portion 32 and the one end portion 51 is reduced, and the actuator 2 can be rotated around the rotating shaft 1 with a small load.

In the first embodiment, a recess 33 is provided at a predetermined outer peripheral position 32a of the conversion cam 3, and the plunger 5
Of the conversion cam 3 via the rotating body 4
2, but without the rotating body 4, for example, at one end 5
1 is formed in a spherical shape, and one end 51 thereof is directly
The contact may be made without limitation.

A second embodiment of the present invention will be described below with reference to FIGS. In the second embodiment, functions different from those in the first embodiment will be described, and members having substantially the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The switch section 6 is provided with a separation cam 65 and is supported by a support section provided on the operation shaft section 62, and rotates with the linear operation of the operation shaft section 62 driven by the plunger 5. Then, the movable contact 64 plate is pressed. That is,
An opening cam 65 for driving the plunger 5 to forcibly separate the movable contact 64 welded to the normally closed fixed contact 63a is provided to form a forced opening mechanism.

Here, as described above, the forced opening mechanism requires a large linear stroke of the plunger 5, and the linear stroke is at most 4 mm to 4.5 mm, and the movable contact 64 is fixed to the fixed contact 63a. , 63b, for example, if about 1.5 mm is required for the switching operation, the remaining 2.5 mm to 3 mm is used for the forced opening operation. Accordingly, since the linear stroke of the operating shaft portion 62 is large, the separation cam 65 is moved by the movable contact spring 64a.
Can be rotated to the position where the button is pushed up, and a forced opening mechanism can be easily added. On the other hand, in the conventional example, the maximum linear stroke of the plunger 5 is about 2 mm. If the switching operation requires about 1.5 mm, the remaining stroke is 0.5 mm.
mm and the forced release mechanism cannot be added.

The operation of the above will be described. Movable contact 64
Is welded to the normally-closed fixed contact 63a, the switch portion 6 is turned off when the movable contact spring 64a does not reverse even when the operating shaft portion 62 moves linearly by about 1.5 mm, and when the plunger 5 further moves linearly. 65 is driven and rotated by the plunger 5 to move the movable contact spring 64a to the normally open fixed contact 63b.
Press toward the side. Then, the movable contact 64 is forcibly peeled off from the normally closed fixed contact 63a and comes into contact with the normally open fixed contact 63b.

In the limit switch according to the second embodiment, as described above, the opening cam 65 for forcibly opening the movable contact 64 welded to the normally closed fixed contact 63a is provided in the switch section 6. Therefore, the plunger 5 linearly moves with a large linear stroke to drive the movable contact 64,
The welded movable contact 64 can be easily separated from the normally closed fixed contact 63a.

In the second embodiment, the forcible opening mechanism for forcibly opening the movable contact 64 from the normally closed fixed contact 63a is formed by the opening cam 65. It may be formed by the above mechanism, and is not limited.

[0038]

According to the first aspect of the present invention, since the conversion cam is formed so that the distance from the center of rotation to the center of rotation increases as the distance from the predetermined position to the both sides increases, the end of the plunger is fixed to the predetermined position. The distance between the one end and the rotation center of the conversion cam becomes longer as it comes into contact with the outer circumference of the conversion cam farther from the outer circumference position, so that the linear stroke of the plunger can be increased and the rotation angle of the actuator can be increased. To make adjustments during installation easier,
According to the second aspect of the present invention, the detection body can be prevented from being damaged even if it shakes greatly in a contact state, and in addition to the effect of the first aspect, a concave portion is provided at a predetermined outer peripheral position of the conversion cam. At the same time, a rotating body is provided at one end where the plunger rotates by the rotation of the outer peripheral portion of the conversion cam, and the plunger abuts on the outer peripheral portion via the rotating body. The actuator rapidly rises and the switching operation in which the movable contact comes into contact with the fixed contact can be accelerated, and the friction between the outer periphery and one end is reduced. Can be moved.

According to a third aspect of the present invention, in addition to the effect of the first or second aspect, a forcible opening mechanism for forcibly opening the movable contact welded to the fixed contact is provided in the switch section. Therefore, the plunger moves linearly with a large linear stroke to drive the movable contact, and the welded movable contact can be easily separated from the fixed contact.

[Brief description of the drawings]

FIG. 1 is a front partial sectional view showing a first embodiment of the present invention.

FIG. 2 is a partial perspective view of the same.

FIG. 3 is a front view of the same.

FIG. 4 is a side sectional view of the same.

FIG. 5 is a correlation diagram showing a relationship between a rotation angle of the actuator and a straight stroke of the plunger.

FIG. 6 is a front view showing a second embodiment of the present invention.

FIG. 7 is a side sectional view of the same.

FIG. 8 is a front partial sectional view showing a conventional example.

FIG. 9 is a partial perspective view of the same.

FIG. 10 is a side sectional view of the same.

FIG. 11 is a perspective view of the same.

FIG. 12 is a front view showing another conventional example.

FIG. 13 is a front view of the plunger in contact with the pivot shaft that has been rotated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation axis 2 Actuator 2a Initial position 3 Conversion cam 31 Rotation center 32 Outer part 32a Predetermined outer part position 33 Concave part 4 Rotating body 5 Plunger 51 One end part 6 Switch part 63a Normally closed fixed contact (fixed contact) 63b Normally open Fixed contact (fixed contact) 64 Movable contact 65 Release cam (forced release mechanism)

Claims (3)

[Claims] A rotating shaft, an actuator supported by the rotating shaft and abutting against a detection body and rotating from an initial position to both sides around the rotating shaft; and a rotation center and an outer peripheral portion. A conversion cam whose outer peripheral portion rotates from a predetermined outer peripheral portion position corresponding to the initial position of the actuator to both sides of the outer periphery to convert to linear operation, and a plunger whose one end abuts against the outer peripheral portion of the conversion cam to perform linear operation. A switch section driven by a plunger so that a movable contact comes into contact with and separates from a fixed contact. The conversion cam, wherein the distance between the outer peripheral portion and the rotation center is determined from the position of the predetermined outer peripheral portion. A limit switch formed so as to become longer as it goes away to both sides of the outer periphery. 2. The conversion cam is provided with a concave portion at the predetermined outer peripheral portion, and the plunger is provided at one end with a rotating body that rotates by the rotation of the outer peripheral portion of the conversion cam, and via the rotating body. 2. The limit switch according to claim 1, wherein the limit switch is formed so as to contact the outer peripheral portion. 3. The switch unit is provided with a forced opening mechanism for forcibly separating the movable contact welded to the fixed contact by being driven by the plunger. The limit switch according to claim 2.