JPH042015A - Plunger type limit switch and its drive mechanism - Google Patents

Abstract

PURPOSE:To eliminate the need for micro-adjustment work on fixing and positioning a plunger type limit switch and at the same time to prevent exerting unreasonable external-force on a switching contact mechanism so as to safely protect the limit switch by incorporating a specified function into a direct motion plunger mechanism paired with the limit switch. CONSTITUTION:When a compression coil spring 11 pushes a plunger 9 into a plunger mechanism, it transmits its operating force to an operating rod 8 so as to actuate a switch 4, and absorbs such an excessive stroke applied to the plunger 9 that the plunger goes over the actuating position of the switch 4 on some occasion. A compression coil spring 15 absorbs some positioning inequality and some positioning errors when the limit switch is fixed. A stopper 17 locks the switching operating-rod 8 at the position where the rod 8 has just moved to its switching position, and it protects a switch contact mechanism against the case where external force more than that necessary to cause the actuation of the switch is applied from the side of the plunger. An auxiliary motion roller 19 of the plunger 9 is engaged with and constrained in a cam groove 22 formed in a rotating plate 21 forming a positive motion cam.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a structure of a plunger-type limit switch that detects mechanical quantities such as the position, angle, and displacement of an object to be detected, and a structure that uses the plunger-type limit switch. The present invention relates to a drive mechanism for a limit switch that detects the rotational position of a rotating body.

[Conventional technology]

BACKGROUND ART Various types of limit switches, such as plunger type and roller arm type limit switches, classified by actuator type, are conventionally known.

On the other hand, as an example of a device for detecting the rotational position of a rotating body using a limit switch, a detection device as shown in FIG. 5 has been conventionally used. In FIG. 5, 1 is the rotating body to be detected, 2
is a lever-shaped striker attached to the shaft 3 of the rotating body 1;
1, 4I [ are limit switches, 5 is the switch mounting board. Here, a roller arm type limit switch is adopted as the limit switch 41, 411, and the limit switch 41
．． 4n are arranged on the left and right sides of the rotating body 1.

The structure of the roller arm type limit switch 4 is disclosed in, for example, Japanese Utility Model Publication No. 46-2599.

With this configuration, when the rotating body 1 rotates by a predetermined angle clockwise from the neutral position shown by the solid line in the drawing, the striker 2 swings the roller arm 4a of the limit switch 42, thereby operating the switch. Conversely, the rotating body 1 rotates counterclockwise, and the mint switch 4■ operates. Note that when the rotating body 1 returns to its original position, the roller arm 4a of the limit switches 4I, 411 returns to its original position by the action of a return spring built into the switch.

[Problem M to be Solved by the Invention] By the way, the conventional rotational position detection device shown in FIG. 5 has the following problems.

(1) If the environmental conditions at the installation location are poor and dust that has entered the case of the limit switch from the surrounding area during use adheres to the bearing of the roller arm and causes a build-up, the roller arm will not move even after the striker has been removed. The blade may not return smoothly due to the spring force, which causes the limit switch to lose its position detection function.

(2) In order to correctly detect the rotational position of a rotating body with a limit switch, it is necessary to correctly align the relative positions of the roller arm, which is the actuator, and the striker on the rotating body side. Installation is time-consuming as it requires troublesome fine-tuning of positioning.

The present invention has been made in consideration of the above points, and is aimed at direct-acting plunger-type limit switches, and provides an easy-to-handle limit switch that requires almost no troublesome positioning adjustment when installing the switch in a predetermined position. It is an object of the present invention to provide a drive mechanism for a limit switch, which can operate the switch reliably without being affected by the structure or the surrounding environment such as dust, and can correctly detect the rotational position of a rotating body.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides (1) a plunger mechanism incorporated in a plunger type limit switch, a plunger loosely fitted to the tip of a switching operation rod, and a plunger mechanism incorporated in a plunger type limit switch. a first compression coil spring interposed between the shaft tip of the operating rod and the bottom surface of the plunger; A second compression coil is interposed between a spring seat that abuts across both the tip flange of the rod and a stepped portion formed on the inner peripheral surface of the plunger, and a spring seat provided on the rear end side of the plunger. It is composed of a spring and a stopper mounted on the shaft of the operating rod at a predetermined distance from the rear wall surface of the plunger case.

(2) Also, as a drive mechanism for a plunger type limit switch for detecting the rotational position of a rotating body, a rotary plate with a cam groove is installed on the shaft of the rotating body to be detected, and a plunger type limit switch of the plunger type limit switch is installed on the shaft of the rotating body to be detected. The driven roller attached to the tip is fitted into the cam groove of the rotary plate to connect the rotary body and the limit switch.

(Function) In the configuration described in item (1) above, when the plunger is pushed in by an external force, the first compression coil spring transmits the operating force to the switching operating rod to operate the switch, and also adjusts the operating position of the switch. If an excessive stroke is applied to the plunger beyond the limit switch, the second compression coil spring acts to absorb the overstroke.The second compression coil spring also absorbs slight positioning variations and errors when installing the limit switch. Furthermore, the stopper locks the switching operating rod in that position when it moves to the switch operating position, and protects the switch contact mechanism in the event that more external force is applied from the plunger side. work.

On the other hand, according to the configuration in item (2), the driven roller of the plunger fits into the cam groove of the rotary plate as a positive cam.

Being restrained. As a result, the plunger of the limit switch operates according to the cam groove of the rotating plate as the rotating body rotates, and is forced to move in the return direction, so its movement is inhibited by the influence of surrounding dust etc. This allows the limit switch to stably maintain the function of detecting the rotational position of the rotating body.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Figures 1 and 2 are diagrams of the plunger mechanism of the limit switch, showing the inoperative and operational states of the switch, respectively, and Figures 3 and 4 are diagrams of the drive mechanism of the limit switch that detects the rotational position of a rotating body. It is something that Note that the same members corresponding to FIG. 5 are given the same reference numerals.

First, with reference to FIGS. 1 and 2, the detailed structure of the plunger type limit switch 4, particularly the direct-acting plunger mechanism combined with the limit switch, will be described. That is, the plunger mechanism 6 accommodates a plunger 9 formed as a cylinder with a bottom that is loosely fitted to the tip of the switching operation rod 8 that penetrates the switch case 7 of the limit switch 4 and is pulled out forward. a plunger case 10 whose rear end is attached to the switch case 7; a first compression coil spring 11 interposed between the shaft tip of the operating rod 8 and the bottom surface of the plunger 9; The tip flange 8a of the operating rod 8 is loosely fitted into the
The spring seat 12 is interposed between a spring seat 12 that abuts across both stepped portions 9a formed on the inner peripheral surface of the plunger 9, and a spring seat 14 that is provided on the rear end side of the plunger 9 via a retaining ring 13. Second compression coil spring 15
and a stopper 17 mounted on the shaft of the operating rod 8 at a distance l corresponding to the switching stroke from the bottom surface 16 of the rear end wall of the plunger case lO. Here, the second compression coil spring 15 has a stronger spring force than the first compression coil spring 11. Further, a pair of upper and lower driven rollers 19 are connected to the tip of the plunger 9 via a shaft 1B. A guide roller 20 is attached, of which the driven roller 19 is attached to a cam groove 22 of a rotating plate 21 whose details will be described later, and the guide roller 20 is attached to a linear guide groove parallel to the switch operating direction formed on the base plate 5. It's stuck in 5a. In addition, 23.2
4 is between the rear end surface of the plunger case 10 and the switch case 7, respectively.

A gasket is interposed between the outer peripheral surface of the plunger 9 and the inner peripheral surface of the plunger case 1O to prevent dust, water, etc. from entering.

On the other hand, in FIGS. 3 and 4, the rotating shaft 2 of the rotating body 1 to be detected has the aforementioned rotating plate 2 as a positive cam with a cam groove.
1 is attached, and the rotating plate 2! A pair of arcuate cam grooves 22 are formed at different positions in the circumferential direction and engage with the driven roller 19 of the plunger mechanism 6 installed on the limit switch 41, 41. The contour of the cam groove 22 is such that the radius increases at the end of the groove corresponding to the rotation detection position of the rotating body l.

Next, the switching operation of the plunger type limit switch and the rotational position detection operation of the rotating body will be explained.

First, in FIGS. 1 and 2, FIG. 1 shows the switch in an inoperative state, the plunger 9 is retracted to the right, and the switching operation rod 8 is connected to the second coil spring 15.
is pulled to the right by the spring force, and the switch contact is off. In addition, in this state, the limit switch 4 is installed with some error in the position, so the cam groove 2 of the rotary plate 21
Even if the plunger 9 restrained by the plunger 2 is pulled to the right from the illustrated position, the displacement is absorbed by the second coil spring 15, so the plunger 9
is an actuator, and the free position of both is ensured. Therefore, some positioning errors and variations are allowed when installing the limit switch, and there is almost no need for fine adjustment after installation.

On the other hand, when an external force pushing the plunger 8 to the left is applied from the state shown in FIG. 1, the operating force compresses the first coil spring 11 and is transmitted to the operating rod 8, causing the operating rod 8 to move to the left. do. When the operating rod 8 moves a predetermined stroke l, the switch contact is turned on, and the stopper 17 abuts against the bottom surface of the plunger case lO and is locked at this position. Moreover, the excessive actuator stroke applied to the plunger 9 after the switch operation is absorbed by the coil spring 11 and does not directly act on the contact mechanism of the switch, thereby protecting the contact Il structure of the switch.

Next, in Figures 3 and 4, two limit switches 4
1.4n rotational position detection operation of the rotating body 1 will be explained. First, the illustration shows the rotational position detection state when the rotating body 1 rotates clockwise.The limit switch 4I is inoperative, the limit switch 4■ is activated, and its switch signal causes the rotational position of the rotating body 1 to be detected in the clockwise direction. Detecting rotational position. When the rotating body 1 rotates counterclockwise from this position, the limit switch 4H returns to the inactive state, and when the rotation angle reaches 90', the limit switch 4H switches to the active state. That is, the limit switch 4■ detects the counterclockwise end position of the rotating body 10, and the limit switch 4■ detects the clockwise end position. Moreover,
A driven roller 19 attached to the tip of the plunger 9 is fitted into and restrained by a cam groove 22 of a rotating plate 21 which is a positive cam, and as the rotating body 1 rotates, each limit switch 41 , 41[ are forcibly moved in the operating and non-operating directions. Therefore, even if dust or the like enters the interior of the plunger mechanism 6 and causes some degree of distortion, this will not impede the movement of the plunger 9. We have shown an example where the rotational position is detected using the limit switch 41°4■, but the rotational position is either left or right! 1 to detect
Of course, this can be handled using the basic limit switch.

Further, the rotating body provided in common to the two limit switches may be provided separately for each limit switch, and furthermore, the operating rotation angle of the rotating body is not limited to 90°, but can be set at any angle. You can choose the angle.

〔Effect of the invention〕

A plunger type limit switch according to the present invention.

Since the drive mechanism is configured as described above, it achieves the following effects.

(1) A direct-acting plunger mechanism combined with a limit switch has a first. By incorporating a second compression coil spring and a stopper that regulates the switching stroke, the coil spring absorbs variations in position and excessive stroke applied to the plunger, making it easy to install the limit switch without making fine adjustments to the position. In addition to eliminating the need for the switch, it also functions as a stopper and prevents undue external force from acting on the switch contact mechanism, thereby safely protecting the switch.

(2) As a limit switch drive mechanism for detecting the rotational position of the rotating body, a rotary plate with a cam groove is installed on the shaft of the rotating body, and a driven member is attached to the plunger of the limit switch in the cam groove of the rotary plate. By fitting the rollers and connecting them, the limit switch is operated via the rotating plate.

The plunger can be forcibly moved to a non-operating position, thereby eliminating the possibility that the movement of the plunger will be hindered by the influence of dust or the like that has entered the interior of the plunger mechanism, and the rotational position detection function can be maintained stably.

[Brief explanation of drawings]

1 to 4 show embodiments of the present invention, and FIG.
Figure 2 is a cross-sectional view of the configuration of the plunger mechanism showing the operating and non-operating states of the limit switch, Figures 3 and 4 are side sectional views and plan views showing the drive mechanism for rotational position detection, and Figure 5 The figure is a configuration diagram of a conventional example of a rotational position detection device using a roller arm type limit switch. 4n: Limit switch, 6: Plunger mechanism, 8 Ni-switching scraper, 9 Ni-blunger, lO nib-lunger case, 11: First compression coil spring, 1214 Ni spring seat, 15: Second compression coil spring, 17
: Stopper, 19: Followed roller, 21: Diagram

Claims (1)

[Claims] 1) A plunger-type limit switch in which a plunger is combined with a switching operating rod of a limit switch, and the plunger is used as an actuator to open and close the limit switch by pushing the plunger. A plunger loosely fitted to the tip, a plunger case housing the plunger and attached to the switch case, a first compression coil spring interposed between the shaft tip of the operating rod and the bottom surface of the plunger, and the operating rod. A spring seat is loosely fitted onto the shaft of the operating rod and abuts on both the tip flange of the operating rod and a stepped part formed on the inner circumferential surface of the plunger, and a spring seat provided on the rear end side of the plunger. A plunger type limit switch comprising a second compression coil spring interposed therebetween and a stopper provided on the shaft of an operating rod at a predetermined distance from the rear end wall of the plunger case. 2) A drive mechanism for a plunger-type limit switch for detecting the rotational position of a rotating body, in which a rotary plate with a cam groove is installed on the shaft of the rotating body to be detected, and the plunger-type limit switch's plunger A drive mechanism for a plunger type limit switch, characterized in that a driven roller attached to the tip is fitted into a cam groove of the rotating plate to connect the rotating body and the limit switch.