JP2000179508A - Mounting structure of stroke sensor for hydro-pneumatic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably simplify a cylinder structure by providing a dust seal in a cylinder end face part, mounting a stroke sensor opposed to a magnetic scale of a piston rod, and integrally mounting the stroke sensor in the dust seal. SOLUTION: A dust seal 34 is mounted in a housing 31 by press fitting a base part 36 to a fitting recessed part 33, a magnetic sensor 38 as a stroke sensor, when it is crossed with a magnetic scale 32a, generates an output, and the magnetic sensor is integrally mounted in a lip part 37 of the dust seal 34. In the case of vertical moving of a piston rod 32 by its deflection, vibration, etc., a lip part 37 also follows and moves in the same direction, so that a clearance between the magnetic sensor 38 and the piston rod 32 can be almost fixedly held and sensitivity of the magnetic sensor 38 can be maintained. Since necessity for work of the housing 31 and a support part of the magnetic sensor 38 for its mounting is eliminated, a structure can be markedly simplified, to reduce a cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a sensor for detecting a stroke of a piston rod in a hydraulic and pneumatic cylinder.

[0002]

2. Description of the Related Art A conventional structure for mounting a stroke detection sensor for hydraulic and pneumatic cylinders is disclosed in Japanese Utility Model Application No. 61-193.
No. 296 has been published. As shown in FIG. 6 and FIG. 7 (the same terms and numbers are used in the description), a magnetic scale is formed on the side surface of the piston rod 11 that reciprocates in the cylinder 10. The magnetic sensor 12 is disposed facing the scale at a predetermined interval. The moving distance is detected based on the output of the magnetic sensor 12 generated when the magnetic scale passes through the magnetic sensor 12.

[0003] A collar 14 having a predetermined height is mounted on a tip 13 of the magnetic sensor 12.
A cylindrical holder 16 is fitted and fixed to the collar 14 by press fitting with the base 15 of the magnetic sensor 12 larger than the outer shape of the magnetic sensor 12 interposed therebetween.

The height of the collar 14 is determined so that a predetermined distance between the piston rod 11 and the magnetic sensor 12 is obtained when the collar 14 is inserted into the sensor hole 17 formed in the cylinder 10. An upper portion 16 is provided with a stepped portion 18 for preventing falling off, which is larger than the diameter of the sensor hole 17.

[0005] A spring 20 for pressing the collar 14 against the piston rod 11 via the holder 16 and the magnetic sensor 12 is interposed between the holder 16 and a cover 19 fixed to the cylinder 10. On the other hand, positioning pins 21 and 22 are provided between the cover 19 and the holder 16 and between the holder 16 and the magnetic sensor 12.

The positioning pin 21 is provided on the upper surface of the holder 16 and engages with a hole 23 provided in the cover 19. The positioning pin 22 is inserted into a side surface of the holder 16 and is engaged with a groove 24 provided on the base 15 of the magnetic sensor 12.

Accordingly, if the magnetic sensor 12 is set in a predetermined direction during assembly, the direction of the magnetic sensor 12 can be set accurately.

Even if the piston rod 11 bends or vibrates during operation, the gap between the magnetic sensor 12 and the piston rod 11 is maintained at a predetermined distance so that the magnetic sensor 12 can obtain stable performance. ing.

A dust seal 25 is attached to the end surface of the cylinder 10 at a position outside the magnetic sensor 12 and its tip is brought into contact with the outer peripheral surface of the piston rod 11 to prevent intrusion of dust and the like. ing.

[0010]

However, in the above conventional configuration, the magnetic sensor 12 and the piston rod 1
In order to keep the interval 1 at a predetermined size, the magnetic sensor 12 is vertically fixed by a collar 14 and a holder 16 inserted into a sensor hole 17 formed in the cylinder 10, and the collar 14 is pressed against the piston rod 11. Therefore, even when the piston rod 11 is bent or vibrated, the magnetic sensor 12
The distance between the piston rod 11 and the piston rod 11 must be kept constant, resulting in a problem that the structure is complicated, the number of parts is large, and the cost is high.

The present invention has been completed by paying attention to the fact that the dust seal always moves following the deflection or vibration of the piston rod, and its object is to significantly simplify the structure of the cylinder. Moreover, it is an object of the present invention to provide a mounting structure of a stroke sensor of a hydraulic and pneumatic cylinder capable of always keeping a constant distance between a magnetic sensor and a piston rod.

[0012]

Means adopted by the present invention to solve this problem will be described with reference to the reference numerals used in the embodiments.
In a hydraulic / pneumatic cylinder for detecting a stroke of the piston rod 32 by attaching a stroke sensor 38 to the magnetic scale 32 a of the piston rod 32 and providing the stroke sensor 38 to the dust seal 34.
, The stroke sensor 38 can be moved following the movement of the piston rod 32, and the performance can be maintained. In addition, the structure of the cylinder 31 for attaching the stroke sensor 38 Can be significantly simplified, and the cost can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

First, in FIGS. 1 to 3, a housing 31 constituting a cylinder has a cylindrical shape, and a piston rod 32 reciprocates on an inner peripheral portion. The piston rod 32 is provided with a plurality of magnetic scales 32a on a side surface thereof at a predetermined pitch. A fitting recess 33 is formed in an end surface of the housing 31.

Next, a first embodiment of the dust seal 34 will be described. This is made of a high-molecular synthetic resin, for example, synthetic rubber, and has a base 36 in which a metal ring ring 35 is embedded, and a lip 37 protruding conically from the base 36 to the side.

The dust seal 34 is attached to the housing 31 by pressing the base 36 into the fitting recess 33. The contact portion 37a at the tip of the lip portion 37 is in contact with the outer periphery of the piston rod 32. The contact portion 37a at the tip follows the movement of the piston rod 32 while pressing the outer periphery thereof, and removes dust adhering to the surface of the piston rod 32.

Magnetic sensor 38 as a stroke sensor
Is for generating an output when it crosses the magnetic scale 32a, and is integrally attached to the lip portion 37 of the dust seal 34. The means may be integrally molded with the dust seal 34 or the molded dust seal 3
4 may be attached by adhesion or the like.

The magnetic sensor 38 and the piston rod 3
2 is provided with a predetermined gap.

According to the first embodiment, when the piston rod 32 moves up and down in the figure due to bending or vibration, the lip portion 37 of the dust seal 34 also moves in the same direction. And piston rod 3
The relative relationship between the two does not change much, the gap between the two can be kept almost constant, and the sensitivity of the magnetic sensor 38 can be maintained.

Further, since the housing for mounting the magnetic sensor 38 is not required as in the prior art, and various parts for supporting the magnetic sensor 38 are not required, the structure can be significantly simplified and the cost can be reduced. This has an excellent effect of reducing the amount of light.

FIG. 4 shows a second embodiment, which is a so-called double lip type dust seal 41 in which contact portions 41a are formed on both sides of a magnetic sensor 38.

FIG. 5 shows a dust seal 42 according to a third embodiment.
The magnetic sensor 38 is provided above the contact portion 42a.

In these second and third embodiments,
In addition to the effects of the first embodiment, the movement amount of the magnetic sensor 38 is the same as the movement amount of the contact portions 41a and 42a, that is, the movement amount of the piston rod 32, and the followability of the piston rod 32 to bending and vibration is further improved. It is effective.

[0024]

According to the present invention, in a hydraulic / pneumatic cylinder in which a dust sensor is provided on an end surface of a cylinder and a stroke sensor is attached to face a magnetic scale of a piston rod to detect a stroke of the piston rod, the stroke sensor is integrated with the dust seal. Since it is attached, the stroke sensor can be moved following the deflection or vibration of the piston rod, and the performance can be maintained.
In addition, the structure of the cylinder for mounting the stroke sensor can be remarkably simplified, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of the present invention.

FIG. 2 is a side view.

FIG. 3 is a plan view.

FIG. 4 shows a second embodiment of the dust seal.

FIG. 5 is a third embodiment of the dust seal.

FIG. 6 is a vertical sectional front view showing a conventional example.

FIG. 7 is a view taken along line AA in FIG. 6;

[Explanation of symbols]

 31 Housing (cylinder) 32 Piston rod 33 Fitting concave part 34 Dust seal 34a Inner peripheral part 35 Magnetic sensor (stroke sensor) 36 Base 37 Lip part 37a contact part 41 Dust seal 41a contact part 42 Dust seal 42a contact part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA02 BA05 CA31 CA34 DB04 GA52 GA66 ZA01 3H081 AA03 BB02 BB03 CC23 EE07 GG06 GG15 GG22 3J043 AA13 BA08 CA02 CB13 DA06 DA10

Claims (1)

[Claims] 1. A hydraulic / pneumatic cylinder for detecting a stroke of a piston rod by providing a dust seal on an end surface of a cylinder and mounting a stroke sensor opposite to a magnetic scale of a piston rod, wherein the stroke sensor is integrated with the dust seal. A mounting structure for a stroke sensor of a sensor hydraulic pneumatic cylinder, which is attached.