JPH11149847A - Limit switch - Google Patents

Abstract

(57) [Summary] [Purpose] The structure is simple, the size can be reduced, the service life is long, and there is no risk of operation failure. An operation plunger unit is disposed opposite to a flat surface of a cam portion of a rotation shaft rotatably supported by a head housing, and a limit for switching an internal switch through the operation plunger unit. The operation plunger unit 26 includes a mounting base 27 mounted on the head housing, a movable spring receiving member 29 fitted to the mounting base so as to be axially movable, and a coaxial shape with the spring receiving member. Plunger 2 fitted to the mounting base so as to be axially movable.
8 and a return spring 31 for pressing the spring receiving member and the plunger against the flat surface of the rotating shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a limit switch used for, for example, positioning control of a moving object in various production facilities or industrial robots.
The present invention relates to a limit switch having left-right and one-side operation functions.

[0002]

2. Description of the Related Art Hitherto, a limit switch of this type has been known as shown in FIG. In the figure, 1
Is a switch housing. This switch housing 1 is composed of a case body 3 containing an internal switch 2 and a cover 4, and a plurality of set bolts 23
The head housing 5 is detachably attached by using. The shaft hole 6 of the head housing 5 has a collar 7.
A rotating shaft 9 is rotatably supported via an O-ring 8 and one end of the rotating shaft 9 is led out of the head housing 5. A roller 12 supported by a shaft 13 is Actuator 10 is fitted and fixed with screw body 11.

The rotating shaft 9 is disposed so that its axis a is orthogonal to the axis b of the operating rod 22 of the internal switch 2. The rotating shaft 9 is positioned on the axis b of the operating rod 22. , A flat cam portion 9b is formed. A cylindrical bottomed spring receiving member 14 is placed on the cam portion 9b, and a coil-shaped return spring 15 is stretched between the spring receiving member 14 and the inner wall surface of the head housing 5 in a compressed state. , And applies a rotation returning force to the rotating shaft 9.

On the other hand, an operation plunger 16 is held between the cam portion 9b and the operation rod 22 so as to be axially movable in the direction of the axis b in the switch housing 1. The operation plunger 16 has a cylindrical shape. Plunger body 17 and auxiliary plunger 18 fitted in plunger body 17
And a buffer spring 19 interposed between them, and a pressing element 20 for pressing the operation rod 22 is fixed to the tip of the auxiliary plunger 18.

[0005] Further, the upper end of the operation plunger 16,
That is, a pressing projection 25 formed in an L-shape is provided upright at an end portion opposed to the flat cam portion 9b via a fixing portion 24 such as a caulking means. Further, the pressing projection 25
Can rotate together with the operation plunger 16 around the axis b of the operation rod 22 of the internal switch 2 inside the head housing 5.
The contact position of the pressing surface 25a of the pressing protrusion 25 with respect to the center position, the left side or the right side can be adjusted.

Next, the operation of the above configuration will be described. When an object to be detected, such as a workpiece, comes into contact with the roller 12, the actuator 10 rotates integrally around the rotating shaft 9 against the spring force of the return spring 15, and the flat cam portion 9b The operation plunger 16 is pressed via the pressing protrusion 25 by the tilting of the internal switch 2 to perform the switching operation. On the other hand, when the cam portion 9b is tilted, the spring receiving member 1
When the pressing force of the actuator 10 is released, the return spring 15 is returned to the original position by the restoring force of the return spring 15 because the actuator 4 is displaced and compresses the return spring 15.

In the above-described configuration, depending on the mode of use, when the actuator 10 is to be operated in the right direction, that is, in the case where switching that is linked only when the actuator 10 is operated in the direction of arrow c around the axis a of the rotary shaft 9 is obtained. , The pressing projection 25 is integrated with the operation plunger 16 by the operation rod 22 of the internal switch 2.
Is pivoted in the direction of arrow e about the axis b of the cam portion 9b so that the pressing surface 25a of the pressing projection 25 is flat.
Is selected and set so that it only hits the right side during the right operation.

On the other hand, when the actuator 10 is operated on the left side, that is, when the switching is performed only when the actuator 10 is operated around the axis a of the rotating shaft 9 in the direction of arrow d, the pressing projection 25 is required. Is turned around the axis b of the operating rod 22 in the direction of the arrow f, and the pressing surface 25a of the pressing protrusion 25 is selectively set so as to hit the flat surface 9c of the cam portion 9b only at the time of the left operation. . Further, the pressing surface 25a of the pressing protrusion 25 is replaced with the flat surface 9c of the cam portion 9b.
When the actuator 10 is rotated in either the left or right direction, the pressing projection 25 is pushed down by the tilting of the cam 9b. The operation plunger 16 is pushed down in conjunction with the downward movement of the lever 25, so that the internal switch 2 can be switched.

[0009]

By the way, according to the above construction, the rotating shaft 9 is formed with the cam portions 9b having the flat cam surfaces 9c and 9d on both sides facing each other. The spring receiving member 14 is placed on one side surface 9d of the cam 9b and the return spring 15 is housed in the head housing 5, and an operation plunger 16 facing the spring receiving member 14 is incorporated into the other side surface 9c of the cam portion 9b. The return spring 15 and the operation plunger 16 must be integrated into two places.
Waste space 5 for accommodating 5 in head housing 5
(a), the size is large, the conversion mechanism is complicated, and the efficiency of assembly work is poor. Moreover, the rotating shaft 9 is inserted into the shaft hole 6,
It is extremely difficult and troublesome to push the spring receiving member 14 into the space 5a of the head housing 5 against the spring reaction force of the return spring 15 and store the operation plunger 16 inside the head housing 5. In particular, since the pressing projection 25 of the operation plunger 16 has a structure in which the pressing projection 25 contacts the cam surface 9c in a one-sided state displaced from the axis b of the operation rod 22, excessive force is applied to the rotating shaft 9 and the operation plunger 16. However, there is a problem that it always works and causes a malfunction, resulting in a short service life. In addition, the mechanical strength must be increased and high-precision bearing members 7 and 33 must be provided, resulting in high cost.

An object of the present invention is to provide an inexpensive limit switch which has a simple structure, can be miniaturized, has a long service life, and is free from malfunctions. .

[0011]

According to a first aspect of the present invention, there is provided a limit switch, wherein an operation plunger unit is disposed opposite to a flat surface of a cam portion of a rotating shaft rotatably supported by a head housing, and the operation plunger unit is provided. A limit switch for switching an internal switch through the operation plunger unit.
A mounting base mounted on the head housing, a movable spring receiving member fitted to the mounting base so as to be axially movable,
A plunger coaxially fitted to the spring receiving member and axially movably fitted to the mounting base; and a return spring for pressing the spring receiving member and the plunger against a flat surface of the rotating shaft. The internal switch is configured to perform a switching operation by an axial movement of a plunger interlocking with the rotation of.

In a limit switch according to a second aspect of the present invention, the mounting base is formed integrally with an outer cylinder and an inner cylinder mounted on a head housing, and a movable spring receiving member is axially movable on the outer cylinder. Along with fitting, the plunger is fitted to the inner cylinder so as to be axially movable, and the spring receiving member and the locking projection protruding from the plunger are engaged with the engagement grooves formed in the two cylinders. The other end of the return spring is retained and retained, and the other end of the return spring is supported by a spring receiving seat protruding from the mounting base. In the limit switch according to the third aspect of the present invention, an auxiliary plunger is axially movably fitted to the plunger, a buffer spring is interposed between the plungers, and the auxiliary plunger is inserted into an engagement groove formed in the plunger. The latching projections protruding from the plunger are engaged to prevent the plunger from coming off, and the shaft movement of the plunger interlocking with the rotation of the rotating shaft is transmitted to the auxiliary plunger via the buffer spring to switch the internal switch. It is characterized in that it is configured to operate.

According to a fourth aspect of the present invention, there is provided a limit switch, wherein a cam portion of the rotary shaft is formed to have a substantially trapezoidal cross section, and the internal switch is turned at a position where the rotary shaft is turned by about 90 ° around an axis from a neutral position. Is configured to perform a switching operation. A limit switch according to a fifth aspect of the present invention includes a mounting base, a movable spring receiving member,
The plunger and the auxiliary plunger are made of a synthetic resin material.

[0014]

According to the first aspect of the present invention, the movable spring receiving member is axially movably fitted to the mounting base mounted on the head housing, and the plunger is disposed coaxially on the spring receiving member. The operation plunger unit is constructed by axially movably fitting the mounting base, and pressing the spring receiving member and the plunger against the cam portion of the rotary shaft with a return spring. The operation plunger unit only needs to be mounted, and it is integrated into one place. With a simple structure, useless space can be minimized and the size can be reduced. Since it suffices to carry out the operation after the insertion into the shaft hole of the housing, the housing operation is extremely easy, and the efficiency of the assembly operation is improved. In the non-operating state, the pressing projection of the plunger and the top of the movable spring receiving member abut on the flat surface of the cam portion so that the operating plunger unit is not displaced from the axis of the operating rod. Due to the structure, there is no possibility that unreasonable stress is constantly applied to the rotating shaft and the operation plunger unit, and the operation is stable and the life is long.

According to the second aspect of the present invention, the mounting base mounted on the head housing is formed integrally with the outer cylinder and the inner cylinder, and the outer cylinder is provided with the movable spring receiving member. The spring receiving member and the engaging projection of the plunger are engaged with the engaging grooves of the two cylindrical bodies to prevent the spring from coming off, and the return spring is seated on the spring receiving seat protruding from the mounting base. Since the other end is supported, the assembling work is easy without losing each component of the operation plunger unit.

According to the third aspect of the present invention, the plunger and the auxiliary plunger are engaged with each other, and the axial movement of the plunger is transmitted to the auxiliary plunger via the buffer spring to switch the internal switch. A long stroke limit switch can be obtained with stable operation. According to the fourth aspect of the present invention, since the cam portion of the rotary shaft is formed to have a substantially trapezoidal cross section, the internal switch is switched at a position where the rotary shaft is turned by about 90 ° around the axis from the neutral position. A limit switch that can be obtained. According to the fifth aspect of the present invention, an inexpensive limit switch can be provided by configuring the mounting base, the movable spring receiving member, the plunger and the auxiliary plunger with a synthetic resin material.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an example of a limit switch according to the present invention, in which main parts are cut away. In the figure,
Reference numeral 1 denotes a switch housing.
Is composed of a case body 3 containing an internal switch 2 and a cover 4, and a plurality of set bolts 2
3, the head housing 5 is detachably mounted. A rotating shaft 9 is rotatably supported in the shaft hole 6 of the head housing 5 via a seal member 8 without requiring a bearing member. One end of the rotating shaft 9 is led out of the head housing 5 and An actuator 10 having a roller 12 supported by a shaft 13 is fitted into the lead-out portion 9a, and is fixed by a screw body 11.

The rotating shaft 9 is disposed so that its axis a is orthogonal to the axis b of the operating rod 22 of the internal switch 2. The rotating shaft 9 is positioned on the axis b of the operating rod 22. , A cam portion 9b having a semicircular cross section is formed. An operation plunger unit 26 is mounted on the head housing 5 between the flat surface 9c of the cam portion 9b and the operation rod 22.
6 is a cylindrical mounting base 27, a plunger 28 and a movable spring receiving member 29 fitted to the mounting base 27 so as to be axially movable, an auxiliary plunger 30 fitted to the plunger 28, and a movable spring A return spring 31 for urging the receiving member 29 with a spring force;
And a buffer spring 32 interposed between them.

The mounting base 27 includes an outer cylinder 27a and an inner cylinder 27b formed coaxially and integrally with the outer cylinder 27a. A movable spring receiving member having a headed cylinder is formed on the outer cylinder 27a. The engagement protrusion 29 a protruding from the base end of the movable spring receiving member 29 is slidably engaged with an engagement groove 27 c formed in the outer cylinder 27, It is fitted to the mounting base 27 so as to be axially movable. A plunger 28 is fitted in the inner cylinder 27b of the mounting base 27, and a locking projection 28a protruding from the base end of the plunger 28 is formed in an engagement groove formed in the inner cylinder 27b. 27d
And slidably engaged with the mounting base 27 so as to be axially movable. The plunger 2 is inserted into an opening 29c formed in the top 29b of the movable spring receiving member 29.
8, a substantially L-shaped pressing protrusion 28b protruding from the head is fitted to the flat surface 9 of the cam portion 9b of the rotating shaft 9.
c together with the top portion 29b of the movable spring receiving member 29.

Further, an auxiliary plunger 30 is fitted into a cylindrical shaft portion 28c formed at the base end of the plunger 28, and a locking projection 30a projecting from the center of the auxiliary plunger 30 is provided. The shaft 28c is slidably engaged with an engagement groove 28d formed in the shaft 28c, and is fitted to the plunger 28 so as to be axially movable. The movable spring receiving member 2
A return spring 31 is fitted inside 9 and stretches in a compressed state coaxially with the inner cylindrical body 27b over the top portion 29b of the movable spring receiving member 29 and the spring seat 27e of the mounting base 27. . A buffer spring 32 is inserted into the shaft portion 28c of the plunger 28, and stretches in a compressed state coaxially with the return spring 31 over the plunger 28 and the auxiliary plunger 30.

Next, the operation of the above configuration will be described. When a moving object (not shown) comes into contact with the roller 12, the actuator 10 rotates left or right, and the rotating shaft 9 also rotates in the same direction. The rotation movement is converted into a linear movement by the flat surface 9c in 9b and transmitted to the operation plunger unit 26,
The switching is performed by pressing the operation rod 22 of the internal switch 2.

Now, the actuator 10 is connected to the rotating shaft 9
When it is desired to obtain the switching only in the right direction (the direction of the arrow c) around the axis a, the operating plunger unit 26 is moved from the state shown in FIG. 90 ° in the direction of arrow e
By turning, the pressing projection 28b of the plunger 28 with respect to the flat surface 9c of the cam 9b of the rotating shaft 9 is disposed as shown in FIG. 2, and the pressing projection 28b is fixed to the flat surface 9c of the cam 9b. Is selected and set so that it only hits the right side during the right operation.

FIGS. 3A to 3E are schematic illustrations of the operation plunger unit 26 which is skewed only at the time of rightward operation. As shown in FIG. 3A, the rotating shaft 9 is moved around the axis a from the state where the flat surface 9c of the cam portion 9b is in contact with the pressing protrusion 28b of the plunger 28 and the top portion 29b of the movable spring receiving member 29. When the movable spring receiving member 29 is engaged with the plunger 28 and the pressing protruding portion 28b, the return spring 31 is rotated, as shown in FIGS. The auxiliary plunger 30 is pushed down against the spring force of FIG.
, And presses the operation stick 22 of the internal switch 2 to perform switching.

On the other hand, the flat surface 9c of the cam portion 9b
3A in which the abutment is made on the pressing projection 28b of the plunger 28 and the top 29b of the movable spring receiving member 29, as shown in FIGS. 3D and 3E.
Is rotated leftward (in the direction of arrow d) about the axis a, only the movable spring receiving member 29 is pushed down against the spring force of the return spring 31, and the axial movement of the plunger 28 and the auxiliary plunger 30 is stopped. Since this does not occur, the switching operation of the internal switch 2 is not performed. When the cam portion 9b is tilted, the return spring 31 is compressed. When the pressing force of the actuator 10 is released, the return force of the return spring 31 returns to the original position.

The operation plunger unit 26 is shown in FIG.
In the arrangement state shown by, the switching operation of the internal switch 2 can be obtained in conjunction only when the actuator 10 is rotated leftward (direction of arrow d) around the axis a of the rotating shaft 9. In the arrangement shown in FIG. 5, the switching of the internal switch 2 can be performed even if the actuator 10 is rotated around the axis a of the rotating shaft 9 in either the left or right direction (the directions of arrows c and d). You can get the action.

According to the above configuration, the cam portion 9b having a flat cam surface 9c on one side is formed on the rotating shaft 9, and the operation plunger unit 26 may be mounted only on the cam surface 9c. Incorporation is performed at one place, the structure is simple, the useless space is suppressed as much as possible, the size can be reduced, and the assembling work efficiency can be improved. In addition, the mounting of the operation plunger unit 26 may be performed after the rotary shaft 9 is inserted into the shaft hole 6 of the head housing 5.
The storing operation is very easy.

In the non-operating state, the cam 9
The pressing projection 28b of the plunger 28 and the top portion 29b of the movable spring receiving member 29 abut on the flat surface 9c of the operating rod 22b, so that the operating plunger unit 26 is not displaced from the axis b of the operating rod 22. Therefore, the rotation shaft 9
In addition, there is no possibility that unreasonable stress is constantly applied to the operation plunger unit 26, and the operation is stable and the life is long. Therefore, the outer cylinder 27a and the inner cylinder 27b of the mounting base 27 in the operation plunger unit 26,
The plunger 28, the movable spring receiving member 29, and the auxiliary plunger 30 can be made of a synthetic resin, so that the mechanical strength is increased and the cost is reduced because it is not necessary to equip a high-precision bearing member.

Further, the operation plunger unit 26
Is constituted by integrally incorporating an outer cylindrical body 27a, an inner cylindrical body 27b, a plunger 28, a return spring 26, an auxiliary plunger 30, and a buffer spring 32, and the above-described respective components are fitted into engagement grooves 27c, 27d, 28d. Locking projection 2
9a, 28a, and 30a are engaged to prevent them from slipping out and positioning, so that there is no risk of losing each component of the operation plunger unit 22 at the time of the operation mode switching operation, and the assembling work is easy. is there. In addition, by forming the cam portion 9b of the rotating shaft 9 into a substantially trapezoidal cross section, the rotating shaft 9 is internally rotated at a large angular position about 90 ° around the axis from the neutral position as shown in FIG. The switch 2 can perform a switching operation.

[0029]

As described above, according to the first aspect of the present invention, the operation plunger unit may be mounted on the cam portion of the rotating shaft from one side, and the cam plunger unit is integrated into one place, and the structure is simple. The use of the operating plunger unit can be performed after the rotary shaft is inserted into the shaft hole of the head housing, so that the storing operation is extremely easy. And the efficiency of assembly work is improved. In the non-operating state, the pressing projection of the plunger and the top of the movable spring receiving member abut on the flat surface of the cam portion so that the operating plunger unit is not displaced from the axis of the operating rod. Due to the structure, there is no possibility that unreasonable stress is constantly applied to the rotating shaft and the operation plunger unit, and the operation is stable and the life is long.

According to the second aspect of the present invention, since the respective components of the operation plunger unit are engaged with each other and held so as to prevent the components from being removed, the assembling work is easy without losing them. According to the third aspect of the present invention, the plunger and the auxiliary plunger are engaged with each other, and the axial movement of the plunger is transmitted to the auxiliary plunger via the buffer spring to cause the internal switch to perform a switching operation. By operation, a long stroke limit switch can be obtained.

According to the fourth aspect of the present invention, since the cam portion of the rotary shaft is formed to have a substantially trapezoidal cross section, the internal switch is provided at a position where the rotary shaft has a large turning angle of about 90 ° around the axis from the neutral position. Can be obtained. According to the fifth aspect of the present invention, an inexpensive limit switch can be provided by configuring the mounting base, the movable spring receiving member, the plunger and the auxiliary plunger with a synthetic resin material.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a limit switch according to the present invention, in which main parts are cut away.

FIG. 2 is a schematic diagram illustrating an example of an operation of a main part of the limit switch.

FIG. 3 is an enlarged cross-sectional view illustrating an example of the operation of the main part of the limit switch.

FIG. 4 is a schematic diagram illustrating another operation example of a main part of the limit switch.

FIG. 5 is a schematic diagram for explaining still another operation example of a main part of the limit switch.

FIG. 6 is a schematic front view illustrating the operation of the limit switch.

FIG. 7 is a side view showing a main part of a conventional limit switch with a cutout.

[Explanation of symbols]

 2 Internal switch 5 Head housing 9 Rotating shaft 9b Cam 9c Flat surface 26 Operation plunger unit 27 Mounting base 27a Outer cylinder 27b Inner cylinder 27c Engagement groove 27d Engagement groove 27e Receiving seat 28 Plunger 28a Engagement protrusion 28d Engagement Groove 29 Movable spring receiving member 29a Locking projection 30 Auxiliary plunger 30a Locking projection 31 Return spring 32 Buffer spring a Rotating shaft axis

Claims (5)

[Claims] An operation plunger unit is provided opposite to a flat surface of a cam portion of a rotation shaft rotatably supported by a head housing, and a limit switch for switching an internal switch via the operation plunger unit. The operating plunger unit includes a mounting base mounted on the head housing, a movable spring receiving member fitted to the mounting base so as to be axially movable, and a shaft coaxial with the spring receiving member and mounted on the mounting base. The internal switch is constituted by a plunger movably fitted, and a return spring for pressing the spring receiving member and the plunger against a flat surface of the rotating shaft, and the axial movement of the plunger interlocking with the rotation of the rotating shaft. A limit switch configured to perform a switching operation. 2. The mounting base integrally forms an outer cylinder and an inner cylinder mounted on a head housing. A movable spring receiving member is fitted to the outer cylinder so as to be axially movable, and the inner cylinder is formed. The spring support member and the engaging projections provided on the plunger are engaged with the engaging grooves formed in the cylindrical bodies so as to prevent the plunger from coming off. 2. The limit switch according to claim 1, wherein the other end of the return spring is supported by a spring receiving seat protruding from the spring. 3. An auxiliary plunger is fitted to the plunger so as to be axially movable, and a buffer spring is interposed between the plungers, and the auxiliary plunger is protruded from an engagement groove formed in the plunger. The latching projection is engaged so as to prevent it from falling off, and the axial movement of the plunger interlocking with the rotation of the rotary shaft is transmitted to the auxiliary plunger via the buffer spring to switch the internal switch. The limit switch according to claim 1, wherein the limit switch is used. 4. The cam portion of the rotating shaft is formed to have a substantially trapezoidal cross section, and the rotating shaft is substantially 9 degrees from the neutral position around the axis.
The limit switch according to any one of claims 1 to 3, wherein the internal switch is configured to perform a switching operation at a position turned by 0 °. 5. The limit switch according to claim 1, wherein the mounting base, the movable spring receiving member, the plunger, and the auxiliary plunger are made of a synthetic resin material.