JP2674974B2 - Drive mechanism for plunger type limit switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive mechanism for a limit switch that detects the rotational position of a rotating body by using a plunger type limit switch that detects mechanical quantities such as the position, angle and displacement of an object to be detected.

[0002]

2. Description of the Related Art As a limit switch, various types of limit switches such as a plunger type and a roller arm type classified by an actuator system have been conventionally known. On the other hand, as an example of a device for detecting the rotational position of a rotating body by a limit switch, a detecting device as shown in FIG. 5 has been conventionally used. In FIG. 5, reference numeral 1 is a rotating body to be detected, 2 is a lever-type striker mounted on a shaft 3 of the rotating body 1, 4
I and 4II are limit switches, and 5 is a switch mounting substrate. Here, a roller arm type limit switch is adopted as the limit switches 4I and 4II, and the limit switches 4I and 4 are arranged so that the roller 4b attached to the roller arm 4a is positioned on the movement path of the striker 2.
II are arranged on the left and right of the rotating body 1. The structure of the roller arm type limit switch 4 is disclosed, for example, in Japanese Utility Model Publication No. 46-2599.

With such a structure, when the rotary body 1 rotates clockwise by a predetermined angle from the neutral position of the solid line in the drawing, the striker 2
Swings the roller arm 4a of the limit switch 4I to operate the switch. On the contrary, when the rotating body 1 rotates counterclockwise, the limit switch 4II operates. If the rotary body 1 returns to the original position, the limit switches 4I, 4
In II, the roller spring 4a returns to its original position by the action of a return spring incorporated inside the switch.

[0004]

By the way, in the conventional rotational position detecting device shown in FIG. 5, the environmental conditions of the installation location are bad, and dust or the like that has intruded into the case of the limit switch from the surroundings during use is a roller. If it sticks to the bearing part of the arm and causes a bite, the roller arm may not be able to smoothly return by the spring force even after the striker is removed.
This has the disadvantage that the position detection function of the limit switch is lost.

The present invention has been made in view of the above points, and the plunger type limit is provided so that the switch can be reliably operated and the rotational position of the rotating body can be accurately detected without being affected by the surrounding environment such as dust. An object is to provide a drive mechanism for a switch.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention combines a switching operation rod of a limit switch with a plunger, and uses the plunger as an actuator to open and close the limit switch to open and close the rotating body. A plunger type limit switch drive mechanism for detecting a rotational position, wherein the plunger mechanism is loosely fitted to the tip of a switching operation rod, a plunger case accommodating the plunger and attached to a switch case, and an operation mechanism. A spring seat that is loosely fitted on the shaft of the rod and that abuts the tip flange of the operating rod and the stepped portion formed on the inner peripheral surface of the plunger, and a spring inserted between the rear end side of the plunger. When a rotary body with a cam groove is attached on the shaft of the rotary body to be detected, , Which is constituted of a driven roller mounted on the plunger tip to interlocking between the rotor and the limit switch is fitted into the cam groove of the rotating body.

According to this structure, since the driven roller of the plunger is fitted and constrained in the cam groove of the rotating plate as the positive cam, the plunger of the limit switch is
As the rotating body rotates, it is driven by the cam groove of the rotating plate and forcibly moved in the return direction, so there is almost no impediment to movement due to the influence of dust catching. The rotational position detection function of the rotating body can be stably maintained.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the plunger mechanism diagram of the limit switch showing the non-operation and operating state of the switch, respectively, and FIGS. 3 and 4 show the drive mechanism diagram of the limit switch for detecting the rotational position of the rotating body. It is a thing. The same members corresponding to those in FIG. 5 are designated by the same reference numerals.

First, referring to FIGS. 1 and 2, the detailed structure of the plunger type limit switch 4, in particular, the direct-acting type plunger mechanism combined with the limit switch will be described.
That is, the plunger mechanism 6 accommodates the plunger 9 which is a bottomed cylindrical body loosely fitted to the tip end of the switching operation rod 8 which extends through the switch case 7 of the limit switch 4 and is pulled out forward. Plunger case with its rear end attached to the switch case 7
10, a first compression coil spring 11 interposed between the axial tip of the operating rod 8 and the bottom surface of the plunger 9, and a distal end flange portion of the operating rod 8 which is loosely fitted on the axial axis of the operating rod 8. 8a, and a stepped portion formed on the inner peripheral surface of the plunger 9.
9a and a spring seat 12 that abuts on both sides of the plunger 9a, and a spring seat provided on the rear end side of the plunger 9 through a retaining ring 13.
A second compression coil spring 15 interposed between
The operating rod 8 is placed at a distance l corresponding to the switching stroke with respect to the bottom surface 16 of the rear end wall of the plunger case 10.
And a stopper 17 mounted on the shaft of. Here, the second compression coil spring 15 has a spring force stronger than that of the first compression coil spring 11. A pair of upper and lower driven rollers 19 and a guide roller 20 are attached to the tip of the plunger 9 via a shaft 18. Among these, the driven roller 19 is a cam groove of a rotary plate 21 whose details will be described later.
Further, the guide roller 20 is fitted in a linear guide groove 5a formed in the mounting substrate 5 in parallel with the switch operating direction. Note that 23 and 24 are plunger cases, respectively.
A packing which is interposed between the rear end surface of the switch 10 and the switch case 7 and between the outer peripheral surface of the plunger 9 and the inner peripheral surface of the plunger case 10 to prevent intrusion of dust and water.

On the other hand, in FIGS. 3 and 4, the rotary plate 21 as a positive cam having a cam groove is attached to the rotary shaft 3 of the rotary member to be detected 1, and the rotary plate 21 is mounted. A pair of arcuate cam grooves 22 are formed on the outer peripheral surface of the limit switch 4I, 4II. The arcuate cam grooves 22 are fitted to the driven roller 19 of the plunger mechanism 6 mounted on the limit switches 4I and 4II. The contour of the cam groove 22 is set so that the radius is enlarged at the groove end portion corresponding to the rotation detection position of the rotating body 11.

Next, the switching operation of the plunger type limit switch and the operation of detecting the rotational position of the rotor will be described. First, in FIGS. 1 and 2, FIG. 1 shows the inoperative state of the switch, the plunger 9 is retracted to the right, and the switching operation rod 8 is moved to the right by the spring force of the second coil spring 15. The switch contact is off. In this state, even if there is some error in the mounting position of the limit switch 4 and the plunger 9 held in the cam groove 22 of the rotary plate 21 is pulled to the right of the position shown in the figure, the positional deviation is caused. Is absorbed by the second coil spring 15, so that the plunger 9 can secure a free position as an actuator. Therefore, some positioning error and variation in mounting the limit switch are allowed, and fine adjustment after mounting is almost unnecessary.

On the other hand, when an external force for pushing the plunger 9 leftward is applied from the state shown in FIG. 1, the operating force is transmitted to the operating rod 8 by compressing the first coil spring 11 and the operating rod 8 is moved leftward. Move to. When the operating rod 8 moves a predetermined stroke l, the switch contact is turned on and the stopper 17 moves the plunger case 10
It hits the bottom surface of and is locked in this position. Further, the excessive actuator stroke applied to the plunger 9 after the switch operation is not absorbed by the coil spring 11 and does not directly act on the contact mechanism of the switch, whereby the contact mechanism of the switch can be protected.

Next, the operation of detecting the rotational position of the rotating body 1 by the two limit switches 4I and 4II will be described with reference to FIGS. 3 and 4. First, the figure shows the rotational position detection state when the rotating body 1 rotates clockwise, in which the limit switch 4I does not operate, the limit switch 4II operates, and the rotating signal causes the rotating body 1 to rotate clockwise. The position is being detected. When the rotating body 1 rotates counterclockwise from this position, the limit switch 4II returns to the inoperative state, and when the rotation angle becomes 90 °, the limit switch 4I switches to the operating state. That is, the limit switch 4I detects the counterclockwise end position of the rotating body 1, and the limit switch 4II detects the clockwise end position. Moreover, the driven roller 19 attached to the tip of the plunger 9 is fitted and restrained in the cam groove 22 of the rotating plate 21 which is a positive moving cam, and the respective limits are passed through the rotating plate 22 as the rotating body 1 rotates. Plunger 9 for switches 4I and 4II
Is forcibly moved in the direction of motion or non-motion. Therefore, even if dust or the like intrudes into the plunger mechanism 6 and causes a slight bite, the movement of the plunger 9 is not hindered by this. In the illustrated example, the left and right rotational positions of the rotating body 1 are detected by the limit switches 4I and 4II, but when detecting the left or right rotational position, one limit switch can be used. Of course.

The rotary body commonly provided for the two limit switches may be provided separately for each limit switch, and the operating rotation angle of the rotary body is not limited to 90 °. , You can choose any angle.

[0015]

As described above, the drive mechanism for the plunger type limit switch according to the present invention serves as a drive mechanism for the limit switch for detecting the rotational position of the rotating body, and has a cam groove on the shaft of the rotating body. The plate is attached, and the driven roller provided on the plunger of the limit switch is fitted into the cam groove of the rotary plate so that they are connected to each other, so that the limit switch can be operated to the inoperative position via the rotary plate. Since the moving operation can be forcibly performed, there is no possibility that the movement of the plunger is hindered by the influence of dust or the like that has entered the inside of the plunger mechanism, and the rotational position detecting function can be stably maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the configuration of a plunger mechanism showing an inoperative state of a limit switch according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the configuration of a plunger mechanism showing an operating state of a limit switch showing an embodiment of the present invention.

FIG. 3 is a side sectional view showing a drive mechanism for detecting a rotational position.

FIG. 4 is a plan view showing a drive mechanism for detecting a rotational position.

FIG. 5 is a structural layout diagram of a conventional example of a rotational position detecting device using a roller arm type limit switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating body, 2 ... Rotating shaft, 4, 4I, 4II ... Limit switch, 6 ... Plunger mechanism, 8 ... Switching operation rod, 9 ... Plunger, 10 ... Plunger case, 11 ...
1st compression coil spring, 12,14 ... Spring seat,
15 ... Second compression coil spring, 17 ... Stopper, 19 ...
Driven roller, 21 ... Rotating plate, 22 ... Cam groove.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeru Tasaka 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor, Yoshizo Watanabe 1 Nitta, Tanabe, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (56) References: Kaikaihei 2-8833 (JP, U)

Claims (1)

(57) [Claims] 1. A drive mechanism for a plunger type limit switch, wherein a plunger is combined with a switching operation rod of the limit switch, and the plunger is used as an actuator to open / close the limit switch by the pushing operation to detect the rotational position of a rotating body. The plunger mechanism includes a plunger that is loosely fitted to the tip of a switching operation rod, a plunger case that houses the plunger and is attached to the switch case, and a plunger that is loosely fitted to the shaft of the operation rod and that is the tip flange of the operation rod. , And a spring seat abutting the stepped portion formed on the inner peripheral surface of the plunger and a spring interposed between the rear end side of the plunger, and a cam groove on the shaft of the rotary body to be detected. Attach the rotating body with the attached roller, and rotate the driven roller attached to the tip of the plunger. Driving mechanism of a plunger type limit switches, characterized in that the interlocking between the rotor and the limit switch is fitted to the body of the cam groove.