JPH06173910A - Pressure medium cylinder - Google Patents

Abstract

PURPOSE: To provide a pressure medium cylinder having a positioning device capable of precisely position without making a restriction of a mountability or a restriction of an arrangement kind of a cylinder. CONSTITUTION: A piston 4 is positioned in a piston rod free movement type pressure medium cylinder and a magnet 14 provided with a polar surface 15 extending approximately perpendicular to a radius of a cross section is disposed on a piston 4 in order to control the movement. The magnet 14 functions as a position generator for a position input device disposed at the outside of the cylinder housing 1. The position input device has a sound wave conductor comprising a magnetostrictive material disposed in a longitudinal side surface 6 extending in a longitudinal direction of the cylinder. A decision device for determining each distance from the position generator is mounted to an end of the sound wave conductor.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pressure medium cylinder.

[0002]

Pressure medium cylinders are known which have a sealed housing in which a sealed piston is guided for longitudinal movement in a cylindrical chamber. The piston is driven by the pressure difference between its two end faces. Forces can be received either by vertical slits through the bracket or by the end face of the housing by means of a band. In order to position a pressure medium cylinder of this kind and control its movement as accurately as possible, it is necessary to be able to ascertain the actual position of the piston with respect to the cylinder housing.

In this type of pressure medium cylinder, on the outside of the cylinder housing, a signal head, which is connected to the piston via a bracket, cooperates with the vertical slit to form about 9 mm.
It is already known to arrange the magnet bands at a 0 ° offset (DE-GM8316167). However, the area transitioning from the bracket must be kept outside the cylinder housing. Moreover, the signal head must be connected to the discriminator via leads. This lead becomes an obstacle, especially in long cylinders.

It is also known to arrange magnet bands in the area of longitudinal slits (DE-GM8503341).
issue). In this case, the cylinder housing can be arranged ignoring the connection between the piston and the signal head, since it is only present in the area of the longitudinal slit, which must be left free anyway. However, the problem of connection with the lead wire remains.

Positioning methods are known in which high radio wave pulses are generated in a sonic conductor made of a magnetostrictive material. This method produces an annular magnetic field around the acoustic conductor. Since there is a pre-existing magnetic field at a location along the acoustic conductor, the superposition of both magnetic fields due to magnetostriction will change the crystallographic structure, thus producing an ultrasonic pulse that continues in both directions. The ultrasonic pulse at one end is absorbed in the buffer section. At the other end of the sonic conductor, the elapsed time between the generation of the current pulse and the arrival of the ultrasonic pulse is measured and from that the distance is determined. In a known device for carrying out this method, a sonic conductor, which is spaced apart and surrounded by a protective tube, is surrounded by a ring containing a number of radially extending short bar magnets. This ring, which surrounds the sonic conductor everywhere, is used as a position generator.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a pressure device that allows a positioning device in any way to accurately determine position without limiting the mountability or the type of arrangement of the cylinders. It is an object to provide a media cylinder.

[0007]

[Means for Solving the Problem] To solve this problem,
The pressure medium cylinder comprises the features of claim 1.
The inventor has found that the use of magnets inside the cylinder housing in place plays the role of a position generator for the conductor elements located outside the housing. That is, the surrounding of the conductor element by the ring element with four magnets is no longer necessary, which means that a mechanical connection between the force-receiving part of the piston and the position generator is required outside the cylinder housing. Will be The pressure medium cylinder provided by the inventor, which solves the problem according to the invention, is therefore particularly suitable. This pressure medium cylinder does not include extra mechanical elements or connecting parts on the outside for carrying out position measurements. Further, since all the discrimination elements are fixedly arranged on the end surface of the conductor element, it is not necessary to connect the piston and the lead wire.

Since conventional piston rod floating pressure medium cylinders often use reed contacts located outside of the housing for closure, the piston is often pre-loaded with a magnet that takes on this extra task. have. In another configuration of the invention, the conductor element comprises a sonic conductor of magnetostrictive material and the discriminating device comprises a pulse generator for generating current pulses.

According to the invention, the sonic conductor is provided in a protective tube surrounding it. The invention provides that the protective tube with the sonic conductor is mounted directly on the outside of the cylindrical housing. Thereby, after the initial determination of the 0 point, no subsequent adjustment is necessary. This attachment has the advantage that, for example, the side portion attached to the outside of the cylinder housing, in particular the groove present there, is fitted with a protective tube and inserted or tightened. Grooves of this kind are often pre-existing in the mounting element for the mounting of the inventor's housing.

In another configuration, the discriminator and / or the pulse generator are located in the area of one end of the cylinder housing. Thereby it is possible to measure along the entire available length of the cylinder housing and thus also to position. The electric wire connected to the discriminating device has the least interference at this position. This is also because there are also hydraulic or pneumatic lines and control lines for the valves that control the movement of the pistons. Other features, details and advantages of the invention will be apparent from the following description of a particular embodiment of the invention with reference to the drawings.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a very simple top view of a piston rod floating pressure medium cylinder. This hydraulic cylinder
It includes a cylindrical housing 1 shown in reduced scale in FIG. The housing 1 is made of aluminum, for example. Both end faces of the housing are each closed by a closure element 2. The closure element 2 comprises a valve that can be arranged directly on the closure element 2 or screwed into an opening there. The valve serves to introduce a pressure medium inside the cylinder housing to control the movement of the piston. Most valves can be controlled by electric wires.

The housing 1 comprises a longitudinally extending slit which is covered by the sealing band 3 both on the outside and on the inside, although only the outer sealing band 3 is visible in FIG. The seal band 3 is made of, for example, steel, is arranged on both sides of the vertical slit, and is held by magnets. The housing 1 comprises a cylindrical inner chamber in which the piston 4 is guided in a vertically movable manner. The piston 4 is partially visible in FIG. The movement of the piston is controlled by the valve and is responsible for maintaining the exact position of the piston.

As can be seen, the piston 4 includes a force receiving portion 5 which receives the movement of the piston and is transmitted to the drive. The side surface portion 6 is provided outside the cylinder housing 1.
Is attached, and the side portion extends in the longitudinal direction of the housing 1 practically the entire length of the housing, and has the nose rib 7 on the side portion. The rib 7 is configured to fit into one of the arcuate grooves 8 on the outside of the housing 1. The arcuate shape of the groove 8 allows the side piece 6 to swivel strongly from the side until it fits into the groove 8 until the lower part 9 of the side piece 6 occupies the condition shown in FIG. The side surface can be fixed by screwing a screw extending substantially in the radial direction with respect to the housing 1 and supporting the outside, through the screw hole of the portion 9 and screwed in.

The side surface portion 6 includes an inner chamber 10 having a circular cross section extending in the longitudinal direction of the side surface portion 6. Into the inner chamber 10, a protective tube (not shown) of a measuring system in which a sonic conductor made of a magnetostrictive material is arranged is inserted. A housing 12 that is connected to the sound wave conductor and the protective tube is arranged at an end portion 11 of one end surface of the side surface portion 6. In this housing all the necessary equipment for determining the spacing and position of the pistons, including the discrimination electronics, are housed.

The piston 4 comprises two bar magnets 13, 14 which intersect the longitudinal direction and which, in cross section, extend at an angle of 90 ° to the direction of the longitudinal slit. Both bar magnets include a pole-forming end face 15, which is oriented so as to be directed towards the magnetic field lines generated in the side part 6 and the acoustic conductor arranged in the side part. Both bar magnets 13, 14 extending parallel to each other are in opposite directions, one polarity towards the sonic conductor being the south pole and the other polarity being the south pole. Then a closed magnetic circuit is created through the acoustic conductor.
Horseshoe magnets can be used instead of both bar magnets for position measurement. However, the bar magnet has the advantage that it can be used to operate a magnetically actuable switch on the outside of the housing in opposite positions.

After mounting the measuring system, that is, after fixing the side surface portion 6, the piston is held at a predetermined initial position, and the zero point at which the device is adjusted is determined. The exact position of the piston can then be determined for each arbitrary condition. On its outside, the piston is movable and has no part to cooperate with the position measuring system. Since all the lead wires are fixedly arranged in the end area of the cylindrical housing, there is no lead wire or the like that is entrained with the movement of the piston. Except for the small required area required by the side part 6 itself, the entire outside of the housing is utilized, for example for providing or mounting a housing with mounting parts.

The position generator, whose position is determined by the discriminator, is already already present for another purpose, namely for the actuation of the magnet switch, anyway, and inside the housing the piston 4
It is constituted by magnets 13 and 14 arranged inside.

[Brief description of drawings]

1 is a partial cutaway view of a pressure medium cylinder according to the present invention.

FIG. 2 is an enlarged view of a cross section of the device of FIG.

[Explanation of symbols]

 1 Cylinder housing 2 Closing element 3 Seal band 4 Piston 5 Force receiving part 6 Side part 7 Rib 8 Groove 10 Circular inner chamber 12 Housing 13 Bar magnet 14 Bar magnet

Claims (6)

[Claims] 1. A cylinder housing (1) made of a ferromagnetic material, a longitudinally extending conductor element of the cylinder housing (1) and a position generator arranged at the end of the conductor element and cooperating with the conductor element. A position detecting device arranged outside the cylinder housing (1) having a discriminating device for determining the distance, and a cylinder housing having magnets (13, 14) having pole faces extending substantially perpendicular to the radius of the cross section. In a pressure medium cylinder provided with a piston (4) movable in the inner chamber of (1), a magnet (13,
14) A pressure medium cylinder, characterized in that 14) serves as a position generator for a position detection device. 2. The pressure medium cylinder according to claim 1, wherein the conductor element has a sound wave conductor made of a magnetostrictive material, and the discriminating device has a pulse generator for generating a current pulse. 3. The pressure medium cylinder according to claim 2, wherein the sonic conductor is arranged in a protective tube surrounding it. 4. Pressure medium cylinder according to claim 3, characterized in that the protective tube is arranged in a side part (6) mounted on the cylinder housing (1). 5. A pressure medium cylinder according to claim 4, characterized in that the side surface (6) is hooked, inserted and clamped in a groove (8) on the outside of the cylinder housing (1). 6. Pressure medium cylinder according to claim 1, characterized in that the discriminator or pulse generator is arranged in the region of one end of the cylinder housing (1).