JPH0828151B2 - Plunger type limit switch - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to a plunger type limit switch that detects mechanical quantities such as the position, angle, and displacement of a detected object.

[Prior art]

As the limit switch, various types of limit switches such as a plunger type and a roller arm type which are 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 denotes a detected rotating body,
2 is a lever-type striker attached to the shaft 3 of the rotating body 1,
4I and 4II are limit switches and 5 is a switch mounting board. Here, roller arm type limit switches are used for the limit switches 4I and 4II.
Limit switches 4I and 4II are arranged on the left and right sides of the rotating body 1 so that the roller 4b attached to the 4a is positioned on the movement trajectory of the striker 2. The structure of the roller arm type limit switch 4 is disclosed in, for example, Japanese Utility Model Publication No. 46-2599. With such a configuration, when the rotating body 1 rotates clockwise by a predetermined angle from the neutral position of the solid line in the drawing, the striker 2 causes the roller arm 4a of the limit switch 4I to swing and the switch to operate. Conversely, if the rotating body rotates counterclockwise, the limit switch 4II operates. When the rotating body 1 returns to its original position, the limit switches 4I and 4II are actuated by the return spring incorporated inside the switches to cause the roller arm 4a to move.
Returns to its original position.

[Problems to be Solved by the Invention]

By the way, in the conventional rotational position detecting device shown in FIG. 5, in order to correctly detect the rotational position of the rotating body by the limit switch, it is necessary to correctly align the relative positions of the roller arm that is the actuator and the striker on the rotating body side. For this reason, there is a drawback in that fine adjustment of positioning is required when mounting the limit switch, and the installation work is troublesome. The present invention has been made in view of the above points, and an object of the present invention is to provide a plunger-type limit switch which is easy to handle and requires little troublesome positioning adjustment when the switch is installed at a predetermined position.

[Means for Solving the Problems]

In order to solve the above problems, the present invention combines a plunger with a switching operation lot of a limit switch, and in a plunger type limit switch that opens and closes the limit switch by pushing the plunger as an actuator, the mechanism of the plunger is A plunger that is loosely fitted to the tip of the switching operation rod, a plunger case that accommodates the plunger and is attached to the switch case, and a first compression coil spring that is interposed between the shaft tip of the operation rod and the bottom surface of the plunger. And a spring seat which is loosely fitted on the shaft of the operating rod and abuts both the tip flange part of the operating rod and the stepped part formed on the inner peripheral surface of the plunger, and is provided on the rear end side of the plunger. A second compression coil spring interposed between the spring seat and It shall be composed of a stopper which is provided on the axis of dude operating rod a predetermined distance from the rear end wall of the run Ja case. With such a configuration, the first compression coil spring transmits the operating force to the switching operation rod when the plunger is pushed in by the external force to operate the switch, and exceeds the operating position of the switch to cause the plunger to move. When an excessive stroke is added, it works to absorb the excess stroke. Further, the second compression coil spring works so as to absorb some variation in positioning and error when mounting the limit switch. Furthermore, when the switching operation rod moves to the switch operating position, the stopper locks the operation rod in that position and protects the contact mechanism of the switch when an external force more than that is applied from the plunger side.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are the plunger mechanism diagram of the limit switch showing the non-operation and operating state of the switch, respectively.
FIG. 4 and FIG. 4 are diagrams showing the drive mechanism of a limit switch for detecting the rotational position of the rotating body. 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, particularly 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 penetrating the switch case 7 of the limit switch 4 and pulled out forward, and the plunger 9. A plunger case 10 having its rear end attached to the switch case 7, a first compression coil spring 11 interposed between the shaft tip of the operation rod 8 and the bottom surface of the plunger 9, and an operation rod 8
On the rear end side of the spring seat 12 and the plunger 9 that are loosely fitted on the shaft of the The second compression coil spring 15 interposed between the spring seat 14 provided via the retaining ring 13 and the bottom surface 16 of the rear end wall of the plunger case 10 is spaced by a distance 1 corresponding to the switching stroke. It is composed of a stopper 17 mounted on the axis of the operation rod 8. Here, the second compression coil spring 15 is the first compression coil spring.
A spring force stronger than 11 is used. 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 in a cam groove 22 of a rotary plate 21 whose details will be described later,
The guide roller 20 is fitted in a linear guide groove 5a formed in the mounting substrate 5 and parallel to the switch operating direction.
In addition, 23 and 24 are provided between the rear end surface of the plunger case 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, respectively, to prevent dust,
A packing that blocks the entry of water. On the other hand, in FIGS. 3 and 4, the rotary plate 3 as a positive cam having a cam groove is provided on the rotary shaft 3 of the detected rotary body 1.
21 is attached to the rotary plate 21, and a pair of arcuate cam grooves 22 are fitted to the driven roller 19 of the plunger mechanism 6 mounted on the limit switches 4I and 4II by changing the position in the circumferential direction. Are formed. 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 second coil spring 15
It is pulled out to the right by the spring force of, and 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 when mounting the limit switch,
Variations are allowed and little adjustment is required after installation. On the other hand, when an external force that pushes the plunger 9 to the left is applied from the state of FIG. 1, the operating force compresses the first coil spring 11 and is transmitted to the operating rod 8, and the operating rod 8
Moves to the left. When the operating rod 8 moves a predetermined stroke l, the switch contact is turned on and the stopper 17 abuts on the bottom surface of the plunger case 10 and is locked at 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, referring to FIGS. 3 and 4, the two limit switches 4
The rotational position detecting operation of the rotating body 1 by I and 4II will be described.
First, the figure shows the rotational position detection state when the rotating body 1 rotates clockwise. 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 reaches 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
4II detects the end position in the clockwise direction. 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. Switch 4
The I and 4II plungers 9 are forcibly moved in the operating and non-operating directions. Therefore, even if dust or the like intrudes into the plunger mechanism 6 to cause a slight bite, the movement of the plunger 9 is not hindered by this. In the example shown in the figure, the rotation position of the rotating body 1 in the left-right direction is limited by a limit switch.
Although an example of detection by 4I and 4II has been shown, it goes without saying that one limit switch can be used to detect either the left or right rotational position. Further, the rotary body commonly provided for the two limit switches may be separately provided for each limit switch, and the operating rotation angle of the rotary body is not limited to 90 °, and any rotary angle may be set. You can choose the angle.

【The invention's effect】

As described above, the plunger-type limit switch according to the present invention is configured by incorporating the first and second compression coil springs and the stopper for restricting the switching stroke into the direct-acting plunger mechanism combined with the limit switch. The variation of the mounting device and excessive stroke applied to the plunger are absorbed by the coil spring, which eliminates the need for fine adjustment of the mounting and positioning, and also prevents the switch contact mechanism from being applied with an undesired external force. Therefore, the switch can be safely protected.

[Brief description of 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]

i ... Rotating body, 2 ... Rotating axis, 4,4I, 4II ... Limit switch, 6 ... Plunger mechanism, 8 ... Switching operation rod, 9 ... Plunger, 10 ... Plunger case, 11 ... No. 1 compression coil spring, 12, 14 ... Spring seat, 15 ... 2nd 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 within Fuji Electric Co., Ltd. (56) References: Actual development Sho 59-170335 (JP, U)

Claims (1)

[Claims] 1. A plunger type limit switch in which a plunger is combined with a switching operation rod of a limit switch, and the plunger is used as an actuator to open and close the limit switch by pushing the plunger, and the mechanism of the plunger is provided at the tip of the switching operation rod. A plunger that is loosely fitted, a plunger case that accommodates the plunger and is attached to a switch case, a first compression coil spring that is interposed between the shaft tip of the operating rod and the bottom surface of the plunger, and the axial direction of the operating rod. Play with,
In addition, a second spring is provided between the spring seat, which abuts both the front flange part of the operating rod and the stepped part formed on the inner peripheral surface of the plunger, and the spring seat provided on the rear end side of the plunger. A plunger-type limit switch comprising a compression coil spring and a stopper provided on the axis of the operating rod at a predetermined distance from the rear end wall of the plunger case.