JPS58225205A - Cylinder containing scale therewithin - Google Patents

Abstract

PURPOSE:To prevent the cylinder from becoming larger and the arrangement from becoming intricate by a structure wherein a hole is provided in a piston rod and a scale and the like are assembled within the hole in a device, in which the cylinder is controlled by measuring the feed of the piston with the scale. CONSTITUTION:A hole 3' is formed in the rod 3 of a piston 2, which is axially shiftable in a cylinder 1, and a magnetic scale 9 is fixed within the hole 3'. A reading head supporting pipe 11, in which the signal wire 10' of a reading head 10 is past, is fixed to a head cover 7. When the piston 2 is moved right or left, the magnetic scale 9 is moved together with the piston, resulting in causing the relative movement between the magnetic scale 9 and the reading head 10 by the amount same as the displacement amount of the rod 3. Consequently, the reading head 10 reads out the displacement amount of the piston 2 so that said read-out amount is fed-back to a cylinder drive section in order to control the cylinder 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder equipped with a scale.

Measuring the piston feed rate of a hydraulic cylinder or pneumatic cylinder to perform servo control is useful when using these cylinders to operate a ν-bot or a machine that requires complex and precise movements. It has become an essential matter. In recent years, optical or magnetic digital
The cylinder is controlled by attaching a scale or the like to the cylinder, reading the piston feed amount, and feeding it back to the cylinder drive unit.

Here, when the scale is to be coupled with the movement of the piston of the cylinder (move together), conventionally the scale has been attached to the outside of the cylinder. This is because it is difficult to incorporate the scale inside the cylinder due to its structure, and in this case, the external shape of the cylinder with the scale attached is large and complicated, making it difficult to handle.

The present invention aims to eliminate the above-mentioned drawbacks by providing a new cylinder with a built-in scale, which incorporates a scale inside the cylinder.

A feature of the invention is that the rod, which moves axially (or displaces) inside the cylinder, is hollow and has a scale and a reading head installed therein. Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention. This example is applied to a power hydraulic (or pneumatic) cylinder. In the figure, (1) is the cylinder outer cylinder, (
2) is the piston, (3) is the piston rod, (3 is the hole drilled in the piston rod, (4) is the piston rod,
Nut, (5) is cushion ring, (6) is cushion valve, 171 is head force/(-, (8
) is the rod cover, (9) is the magnetic scale, Qω is the scale reading head, aυ is the reading head support pipe,
α2 represents a board for a scale reading circuit, and the opposite side represents a connector for connecting to an electronic circuit.

FIG. 2 is a sectional view taken along line A-A' in FIG. 1. In the figure, parts corresponding to those in FIG. 1 are given the same reference numerals. The magnetic scale (9) has a ferromagnetic scale base (
91)% A rubber magnet (92) and a non-magnetic stainless steel cover (93) for protecting the rubber magnet are fixed in the hole (3') of the piston rod (3).

The reading head support pipe aυ is made of stainless steel, for example.
The head cover (fixed to the force) is fixed with a pipe, and the signal line (1) of the read head αO is passed through the pipe.The magnetic scale (9) is not affected by oil or dirt, so when used in this type of cylinder. It is advantageous for the scale base (
91) has a thickness of 1 to 21111 and a hole (3
) is made of iron with approximately the same overall length, its both ends are bent in opposite directions, and the shape of each bent part is adjusted to match the shape of the lying surface of the piston rod (3) and its hole (3'), so that the piston φ The bent portion that matches the cross-sectional shape of the rod (3) is fixed to the open end of the piston-rod (3) with a screw or the like.

FIG. 3 is an explanatory diagram showing an example of a magnetic scale and its reading head. In the figure, (12 shows a scale reading circuit formed on a substrate (121). The reading head uses a magnetic flux density detection sensor using a saturable core, and a rubber magnet (92) of a magnetic scale (9) Pinch the magnetically recorded lattice stripes at 90° as shown in the figure.
Read as a two-phase signal with a phase difference. Digital reading is possible with a resolution (accuracy) of 0.1 on this spot. In the figure, the rubber magnet (92) is drawn thickly.
10 Pa @Il) *L゛ is also ``'' \. The magnetic scale reading circuit as described above is already known, so detailed explanation will be omitted.

With the above configuration, when the piston (2) moves linearly from side to side due to oil or air, the magnetic scale (9) fixed to the piston/1, rod (3) moves along with the piston (2). During the busy movement, the magnetic scale (9) and the fixed reading head αII move relative to each other with the same displacement as the piston rod (3), and the reading head (IG is the displacement of the piston). This is read and fed back to the cylinder drive unit via the connector to control the cylinder.In the example shown in Figure 1, the scale (9) is fixed to the piston rod (3), but the scale (9) is It is theoretically possible to read even if it is fixed to the support pipe αυ and the reading head a1 is fixed to the piston rod (3).

FIG. 4 is a sectional view showing a second embodiment of the present invention. In this example, the present invention is applied to a measuring cylinder. In the figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals. The difference between this example and the one shown in FIG. 1 is that the rod (3) is moved in the axial direction by or against the force of a spring α4 rather than by the force of oil or air.

The spring I consists of a head support pipe holder α9 fixed to one end inside the cylinder outer cylinder (1), and a spring receiver fixed to the outer periphery of the rod (3) and moving inside the cylinder outer cylinder (11) together with the rod (3). is compressed and inserted between the rod (3) and the rod (3).Therefore, the rod (3) is always urged outward and protrudes greatly to the right in the figure before use. When the tip of the cylinder (3) is brought into contact with the object and the cylinder outer cylinder is pressed, the reading head αυ fixed to the cylinder outer cylinder (1) will be moved relative to the magnetic scale (9). The reading head reads the displacement amount of the cylinder outer cylinder (1). Therefore, according to this example, the cylinder outer cylinder (1) moves by the same displacement amount as the displacement of the cylinder outer cylinder (1).
Various lengths and distances can be measured from the amount of displacement in 1). The figure shows the rod (3) being pushed into the cylinder barrel (1).

As explained above, according to the present invention 11, the scale and scale reading head are built inside the cylinder, so the outer shape of the cylinder is not thick (and there is no need to attach anything to the outside of the cylinder). It has the advantage of being extremely easy to handle.Therefore, it is not only suitable for power hydraulic (or pneumatic) cylinders, but also can be used as a measuring cylinder in a very simple manner.

It should be noted that the present invention is not limited to the above-described embodiments, but may be modified in various ways without departing from the gist of the invention as set forth in the claims. For example, the magnetic scale and its reading head may be replaced by another equivalent combination of a scale and its reading device.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along the line A- in FIG. FIG. 4 is a sectional view showing a second embodiment of the present invention. (1)...Cylinder outer cylinder, (3)...Rod, (target...Hollow part of the rod, (9)...
・Scale, a...Scale reading device. Hidemori Matsukuma

Claims (1)

[Claims] Inside the cylinder, a hole BA is formed in the axially movable rod, and a scale or its reading device is fixed to this hollow part, while a scale reading device is fixed to the outer cylinder of the cylinder. A cylinder with a built-in scale, characterized in that the device or the scale is fixed, and when the rod and the outer cylinder of the cylinder move relative to each other, the scale and its reading device move relative to each other.