JPH0720562Y2 - Actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an actuator such as a hydraulic cylinder.

(Prior Art) As a device conventionally used to detect the displacement of an actuator, there is a detection device as shown in FIG.
In this detection device, piston rods projecting from a cylinder tube are integrally provided on both sides of a piston 5 of a hydraulic cylinder 2, and a cylindrical body 50 concentric with the cylinder tube is fixed to the cylinder tube at the projecting portion of one piston rod. The coil 52 of the differential transformer 51 is attached to the inside thereof, and the core 53 inserted into the coil is attached to the piston rod.

When the piston moves due to the hydraulic pressure supplied into the cylinder tube, the fitting length of the core with respect to the coil of the differential transformer 51 changes, so that the displacement amount can be electrically detected.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional differential transformer type displacement detection device, the length of the coil must be long enough to correspond to the piston stroke. There was a problem that the whole length became long.

[Means for Solving Problems] In order to solve the above problems, the present invention employs the following configuration.

That is, in the actuator according to the present invention, rods that move with the piston are provided on both sides of the piston provided in the cylinder tube, and one rod is used as a piston rod for driving another object, and the other rod has an outer circumference. A cylindrical fixed electrode having a diameter slightly larger than that of the rod is provided separately from the cylinder tube at the portion, and the rod is used as the other electrode with respect to the fixed electrode, thereby changing the capacitance caused by the movement of the rod. The feature is that it is detected.

[Operation] When the piston of the actuator moves, the movable rod moves integrally, so that the fitting length of the movable rod with respect to the cylindrical fixed electrode changes, and the capacitance of this portion changes. Therefore, the amount of movement of the piston can be electrically detected.

[Embodiment] FIGS. 1 and 2 show an embodiment of the present invention, in which the displacement detecting device 1 is integrally assembled to a hydraulic cylinder 2 which is an actuator. Piston 5 held in cylinder tube 4 of hydraulic cylinder 2
A pair of rods 7 and 8 protruding in the front-rear direction are integrally attached to the. The front rod 7 is a piston rod that drives another object, and the rear rod 8 is a movable rod that constitutes the displacement detection device 1. Lid plates 10 and 11 are fixed to the openings of both ends of the cylinder tube 4 with bolts,
A bush 13 and a sealing material 14 are provided inside these cover plates. The front end of the front seal material is pressed by a metal plate 16 bolted to the cover plate 10, and the rear end of the rear seal material is similarly pressed to the cover plate 11 by a press plate 18 and an insulating ring 19. Being held down by. A substrate 20 of the displacement detecting device 1 is provided in close contact with the outside of the lid plate 11 on the rear side, and is fixed to the cylinder tube 4 together with the lid plate 11 by a long bolt 22.

A protective cylinder 24 is welded to the substrate 20, and an end member 26 is welded to the opposite side of the protective cylinder. A cylindrical insulator 29 is fitted inside the protective cylinder 24, and a cylindrical fixed electrode 30 is likewise fitted on the inner surface of the insulator. Fixed electrode
The movable rod 8 is concentric with the movable rod 8 and has a diameter slightly larger than that of the movable rod 8.
And the rear side insulating ring 32 fitted inside the end member 26.
It is fixed by and. A through hole 33 is formed in the rear insulating ring 32, and a through hole 34 in the radial direction of the end member 26 is formed.
Is connected to the outside air through. A snap ring 36 is provided at the rear end of the insulating ring 32, and a disc-shaped cap 38 is screwed on the outside thereof. A lead wire 40 inserted through the through hole 39 is connected to the fixed electrode 30,
Further, a manifold is attached to the cylinder tube 4 using the attachment holes 41, ..., And working oil is supplied into the cylinder tube through supply / discharge holes 43, 44 provided in front of and behind the piston 5.

Supply / discharge holes on the rear side of this actuator (hydraulic cylinder) 2.
If the hydraulic pressure is supplied from 44 to the cylinder chamber on the rear side of the piston 5 and the oil on the front side of the piston 5 is discharged from the supply / discharge hole 43 on the front side, the piston 5 moves forward, so that another object is driven by the piston rod 7. can do. If the supply and discharge of the hydraulic pressure is reversed, the piston 5 moves backward. When the piston 5 moves, the movable rod 8 on the rear side also moves integrally, and the capacitance between the movable electrode 8 and the fixed electrode 30 changes. Therefore, the displacement of the piston 5 can be detected by detecting the amount of change. It can be detected electrically. That is, the movable rod 8
The variable capacitor is formed by the fixed electrode 30 and the fixed electrode 30, and the displacement is detected by the change in the capacitance of the capacitor. The displacement detecting device 1 can be used by connecting a lead wire to the actuator 2 and the fixed electrode 30 and connecting to a detecting circuit such as the capacitance type displacement detecting circuit described in JP-B-49-25340. .

Since this displacement measuring device uses the movable rod 8 itself provided integrally with the piston 5 as a constituent member of the capacitance type displacement detector, the total length of the displacement measuring device should be shorter than that of the conventional differential transformer type. You can Since a gap is provided between the fixed electrode 30 and the movable rod 8 and they do not come into contact with each other, the movable rod 8 is free to rotate, and since there is no wear portion, maintenance and the like is easy.

[Effects of the Invention] As is clear from the above description, the actuator according to the present invention uses one of the movable rods provided on both sides of the piston as a piston rod for driving another object, and the outer periphery of the other movable rod. By providing a fixed electrode on the part and using this movable rod as an electrode corresponding to the fixed electrode, the change in the electrostatic capacitance caused by the movement of this movable rod is detected. It became possible to detect it, and it became compact and practically convenient.

[Brief description of drawings]

FIG. 1 is a principle view of the present invention, FIG. 2, FIG. 3, FIG. 4, and FIG.
FIG. 6 and FIG. 6 are explanatory views of a conventional example. 1 ... Displacement detection device, 2 ... Actuator (hydraulic cylinder), 5 ... Piston, 7 ... Piston rod, 8 ...
… Movable rod, 29… Insulator, 30… Fixed electrode

Continuation of the front page (56) References JP-A-53-131858 (JP, A) JP-A-60-4803 (JP, A) Actual opening 57-8909 (JP, U) Actual opening 59-45505 (JP , U)

Claims (1)

[Scope of utility model registration request] 1. A rod which moves together with a piston provided on both sides of a piston provided in a cylinder tube, wherein one rod is a piston rod for driving another object, and the other rod is provided on an outer peripheral portion of the other rod. A cylindrical fixed electrode having a diameter slightly larger than that of the cylinder tube is provided separately from the cylinder tube, and by using the rod as the other electrode with respect to the fixed electrode, a change in capacitance caused by the movement of the rod can be detected. An actuator characterized in that