JPH11306906A - Limit switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized limit switch not using a case, actuator, etc. SOLUTION: A limit switch includes a piezo element 1 and a pressure element 3 installed on a plate part 7 of a slider 4 through a coil spring 2 oppositing to the piezo element 1. The limit switch generates pulse voltage signals when the moving pressing element 3 presses the piezo element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a limit switch.

[0002]

2. Description of the Related Art Conventionally, a limit switch is generally used for position control of a machine or the like, is housed in a sturdy metal case, and has an actuator such as a lever suitable for the case.

[0003] The structure and operation of a conventional limit switch will be briefly described. The limit switch has a minute contact interval and a snap action mechanism, and has a contact mechanism that opens and closes with a specified movement and a specified force. Is covered with a case, and an actuator such as a lever is provided outside the case. When an external force is applied to the actuator, the external force is transmitted to an internal spring mechanism, and the movable contact is moved to open and close the switch.

FIG. 3 is an external perspective view of a conventional limit switch. 3, reference numeral 10 denotes a main body case having a contact mechanism, 11 denotes a lever, and 12 denotes a roller. The roller 12 and the lever 11 are moved in the direction of the arrow in FIG. 3 and operate as an actuator to turn on and off the contact mechanism 10 in the main body 10.

That is, as shown in FIG. 4, when the object 13 moves and the projection 14 contacts the roller 12, the lever 11 operates the contact mechanism in the main body 10 as an actuator.

[0006]

However, in the conventional example, since the case 10 and the actuators such as the lever 11 and the roller 12 are required, the size of this type of limit switch has recently been reduced, but it is still large. There is a problem that becomes.

An object of the present invention is to provide a limit switch which can be reduced in size without requiring a case or an actuator such as a swinging lever.

[0008]

In order to solve the above-mentioned problems, the present invention has a piezoelectric element and a pressure element for pressing the piezoelectric element, and one of the piezoelectric element and the pressure element is a movable member.
The present invention provides a limit switch having a structure in which the pressure sensing direction is attached to the movable direction and the other of the piezoelectric element and the pressurizer is supported forward in the one movable direction.

The piezoelectric element in the limit switch of the present invention and the pressurizing element for pressing the piezoelectric element do not need to be put in a case, and an actuator or the like for operating the piezoelectric element is not required. Therefore, the degree of freedom of the installation location is increased. Further, in the limit switch of the present invention, since a piezoelectric element is used, no extra power supply or battery is required.

In the limit switch according to the present invention, it is preferable that one of the pressurizing element and the piezoelectric element is arranged so as to be position-adjustable in the pressure-sensitive direction, because the adjustment of the limit switch can be easily performed. .

Furthermore, in the limit switch of the present invention, it is preferable that the piezoelectric element is supported by a vibration isolator, because the vibration resistance is improved and a malfunction of the limit switch can be prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, a limit switch according to a first embodiment shown in FIG. 1 will be described. In FIG. 1, 1 is a piezoelectric element, 2 is a coil spring, 3 is a pressurizer, and 4 is a slider. A plate portion 7 projects laterally from the slider 4, and a screw 6 is positioned on the plate portion 7 by a nut 8. Rod 9 in the hole of screw 6
Is fitted, and the pressurizing element 3 is attached to the lower end thereof.

The pressurizing element 3 is elastically attached via a coil spring 2 to a rod 9 which reciprocates with the slider 4. The piezoelectric element 1 is disposed in front of the pressurizer 3 reciprocating by the slider 4, and is supported in such a manner that the pressure sensing direction matches the reciprocating direction of the pressurizer 3.

The slider 4 moves up and down in the direction of the arrow as shown. When the slider 4 moves downward, the piezoelectric element 1 is pressed by the pressurizer 3, and the piezoelectric element 1 generates a pulse voltage. For example, the slider 4 stops moving by this signal (voltage).
It operates to stop the downward movement of.

Further, as described above, the pressurizing element 3 is elastically attached to the plate-like portion 7 protruding from the slider 4 by the coil spring 2 for softening the pressing force on the piezoelectric element 1. Since the mounting position of the pressing element 3 in the moving direction can be changed by turning the nut 8 that engages with the screw 6, adjustment of the gap between the piezoelectric element 1 and the pressing element 3 can be easily performed.

(Second Embodiment) Next, a limit switch according to a second embodiment shown in FIG. 2 will be described. In FIG. 2, the structures and operations of the portions denoted by reference numerals 1 to 4 are the same as those of the first embodiment, and thus the description is omitted. In FIG. 2, reference numeral 5 denotes an anti-vibration support. The anti-vibration support 5 is provided on the support surface of the piezoelectric element 1. This anti-vibration support 5
Is provided, the piezoelectric element 1 is prevented from being vibrated, and a pulse-like voltage is not generated by the vibration, so that the vibration resistance of the limit switch is improved, and the operation can be compensated to prevent malfunction.

Other configurations and operations are the same as those of the first embodiment. As described above, the present invention has been specifically described based on the illustrated embodiments. However, the present invention is not limited to these embodiments, and has specific structures and configurations within the scope of the present invention described in the claims. It goes without saying that various changes may be made.

For example, in the above embodiment, the case where the pulse voltage generated by the piezoelectric element 1 is used as the output of the limit switch has been described. The light emitting element is caused to emit light by the pulsed voltage of 1, and the light (light emission) is detected using (optical means of) an optical fiber or the like, so that the light emitting element is operated as a limit switch without the need for an (electric) signal cable. You can also.

[0020]

As described above, since the limit switch of the present invention does not require a case and an actuator, the size can be reduced, and the degree of freedom of the installation place can be increased. In addition, since a piezoelectric element is used, no extra power supply or battery is required. Further, in the limit switch of the present invention, if one of the piezoelectric element and the pressure element is disposed so as to be position-adjustable in the pressure-sensitive direction by, for example, screwing via a coil spring, the adjustment of the limit switch becomes easy. .

In the case where a vibration isolating means such as a vibration isolating support is provided around the piezoelectric element, the vibration resistance is improved and the limit switch can be prevented from malfunctioning. As a result, the present invention can provide a significantly smaller limit switch than the conventional one.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a limit switch according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a limit switch according to a second embodiment of the present invention.

FIG. 3 is an external perspective view showing a conventional limit switch.

FIG. 4 is an explanatory diagram showing an example of use of a conventional limit switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Coil spring 3 Pressurizer 4 Slider 5 Anti-vibration support 6 Screw 7 Plate part 8 Nut 9 Rod

Claims (3)

[Claims] A piezoelectric element, and a pressure element for pressing the piezoelectric element, wherein one of the piezoelectric element and the pressure element is a movable member,
A limit switch, wherein the limit switch is mounted so that the pressure-sensitive direction is aligned with the movable direction, and the other of the piezoelectric element and the pressurizer is supported in front of the one movable direction. 2. The limit switch according to claim 1, wherein one of said pressurizing element and said piezoelectric element is arranged so as to be adjustable in a pressure-sensitive direction. 3. The limit switch according to claim 1, wherein said piezoelectric element is supported by a vibration isolator.