EP1101953A2 - Fluid pressure motor based on electrorheological fluids - Google Patents

Abstract

Boundary surfaces (7, 8, 12) are formed by opposite surfaces of the cylindrical casing (2) which are spaced apart.

Description

The invention relates to a pressure medium motor based on electrorheological Liquids, one in a cylinder housing guided piston is provided in the cylinder housing forms two variable-volume working chambers, one Inlet hole for the electrorheological fluid with a pressure medium source (pump) is connected, one Outlet hole for the electrorheological fluid with is connected to a tank and arranged in the cylinder housing Valves based on electrorheological fluids, some have a variable-volume working chamber valve gap connecting to the inlet bore or the outlet bore have, the boundary surfaces of the valve gap designed as electrically controllable electrode surfaces are.

Electrorheological fluids are liquids where the rheological properties depending on one electric field are controllable. As a rule, it is in electrorheological fluids to suspensions that means solid particles suspended in a carrier medium are polarizable via the electric field. Because of the engagement of electrorheological fluids as working fluid it has become possible to reduce the number of moving parts in hydraulic Systems significantly. A variety of possible applications, e.g. the use of hydraulic valves, Hydraulic cylinders, vibrators, viscosity couplings, Shock absorbers or engine mounts are in the review article "Applications of the electrorheological effect in engineering practice, Fluid mechanics Soviet research, Vol.8, No. 4, July - August 1979 ".

From DE-OS 197 35 466 a pressure medium motor is based known electrorheological fluids. The control the pressure medium motor is implemented via four integrated in the cylinder electrorheological valves that work as a full bridge with each other are connected. In this known hydraulic motor are the electrorheological valves as annular gap valves formed by the introduced into the cylinder housing wall Bores and mandrels arranged in the bores are formed. The boundary walls are used to generate an electric field of the annular gap as electrically controllable electrode surfaces educated.

The object of the present invention is a hydraulic motor develop with integrated valves such that at even more compact outer dimensions, higher dynamics as well high actuating forces can be achieved.

This object is achieved in that the boundary surfaces are formed, on the one hand, by first housing sections formed on the outer circumferential surface of the cylinder housing and, on the other hand, by second housing sections which are spaced apart from one another.
As a result, a pressure medium motor which is compact with regard to its outer dimensions and with which an even higher dynamic range is achieved. Due to the compact design, a higher hydraulic rigidity can be achieved. Since the pressure medium motor has a low weight, its dynamic rigidity is low. As a result, it can be used in particular in automation technology.

In a development of the invention it is provided that the Valve gaps through boundary surfaces of the cylinder housing as well formed a sleeve concentrically surrounding the cylinder housing become. In this way, a pressure medium motor is realized, which has a mechanically simple structure. In another Design are two in parallel for each valve Flat column provided. Through this training you can higher flow rates can be achieved.

A special feature of the pressure fluid motor is its property the effect electronically on a differential cylinder to achieve a synchronous cylinder. This becomes possible due to the high dynamics of the compact pressure medium motor. The valves are connected as a full bridge and controlled in such a way that the pressures in the variable-volume working chambers A and B are inversely proportional to their respective Behave piston surfaces.

Fig. 1:

einen Längsschnitt durch einen erfindungsgemäßen Druckmittelmotor auf Basis elektrorheologischer Flüssigkeiten;

Fig.2:

einen Querschnitt Y-Z des Druckmittelmotors gemäß Figur 1;

Fig.3:

einen Querschnitt W-X des Druckmittelmotors gemäß Figur 1;

Fig.4:

eine schematische Darstellung der Ansteuerung eines erfindungsgemäßen Druckmittelmotors.

The invention is explained in more detail below using an exemplary embodiment which is shown in FIGS. 1-4. It shows:

Fig. 1:

a longitudinal section through a pressure medium motor according to the invention based on electrorheological fluids;

Fig. 2:

a cross section YZ of the pressure medium motor according to Figure 1;

Fig. 3:

a cross section WX of the pressure medium motor according to Figure 1;

Fig. 4:

a schematic representation of the control of a pressure medium motor according to the invention.

The pressure medium motor 1 shown in FIGS. 1-3 exists from a cylinder housing2, into which a cylindrical Through hole 3 is introduced. In the through hole 3 is a piston 4 with a one-sided outward Piston rod 5 guided axially. The piston 4 divided the cylindrical through hole 3 in two variable volume Working chambers A, B. The cylinder housing2 is from surrounded a sleeve 6 which is concentric with the cylinder housing 2 is arranged. Between the inner surface 7 of the Sleeve 6 and the outer circumferential surface 8 of the cylinder housing 2 This leaves an annular space 9 that extends over the entire axial length of the cylinder housing 2 extends. Sleeve 6 and Cylinder housing 2 are uniform over the circumference over four Distributed plastic strips 10, which are in axial Direction over the entire length of the cylinder housing 2 extend, connected to each other. By arranging the Plastic strips 10, the annular space 9 is in four of the same size Partitions 11 divided, which are sealed from each other.

The subspaces 11 are each formed by a tubular segment element 12, which extends over the entire axial length of the cylinder housing 2 extends into two flat columns 13 divided, each parallel spaced cylindrical boundary surfaces exhibit. The tube segment elements 12 are each held at the end in a plastic strip 10 by the flat gaps 13 are sealed from one another. Four valves are thus between cylinder housing 2 and sleeve 6 based on electrorheological fluids (a1, a2, b1, b2) formed, each having two flat gaps 13. In an embodiment not shown could for each Valve a plurality of flat gaps arranged in parallel be provided.

The electrorheological valves a1, a2, b1, b2 are capacitors executed, the electrode surfaces on the one hand through the boundary surfaces of the pipe segment elements 12 and on the other hand through the inner surface of the sleeve 6 or the outer surface of the cylinder housing 2 are formed.

The tube segment elements 12 are each one from the Pressure medium motor led out as an electrical connection serving isolated mandrel 14 with a high voltage supply connected and individually electrically controllable. The Cylinder housing 2 and sleeve 6 are each grounded. The Plastic strips 10 are used for insulation.

The cylinder housing 2 has end parts 15, 16 provided that have a cylindrical projection 17 in the middle, which closes the cylindrical through hole 3. The cover parts 15, 16 have the same radial extent like the sleeve 6. In the cover parts 15, 16 are each two essentially semi-cylindrical chambers 18, 19 and 20, 21 introduced, which to the cylinder housing 2 and the cylinder housing 2 surrounding sleeve 6 have. Chambers 18, 19 and 20, 21 are via a radially extending separator 22, 23 separated from each other.

The end parts 15, 16 are rotated by 90 ° arranged to each other so that the dividers 22, 23rd are aligned perpendicular to each other. The chamber 18 is over an axial through hole made in the cover part 15 24 connected to a pressure medium pump. Chamber 19 is an axial introduced into the cover part 15 Through hole 25 connected to a tank. Chamber 20 stands over a bore made in the cylinder housing2 26 in connection with the variable-volume working chamber A, the chamber 21 is located in the cylinder housing 2 introduced bore 27 with the variable-volume working chamber B in connection.

Due to the arrangement described above, the chamber 18 stands with the electrorheological valves a1 and a2 and the chamber 19 in connection with the electrorheological valves b1 and b2. Furthermore, chamber 20 is with the flat columns 13 of the Valves a1 and b2 and chamber 21 with the flat columns 13 of the Valves a2 and b1 in connection.

Based on Figure 4, which is a schematic representation of the circuit of the four electrorheological valves to a full represents the bridge, the functionality or control is closer described. The lines denote the flow channels, through which the electrorheological fluid acts as a working fluid coming from a pump P to a tank. Between the pump P and the tank T are two parallel flow branches available. The top branch contains connected in series the electrorheological valves a1 and b2 the lower one Flow branch the electrorheological valves a2 and b1. The electro-rheological valves are schematic as circular areas shown. Between the electrorheological valves a1, b2 of the upper flow branch is the variable volume Working chamber A of the pressure medium motor connected, between the electrorheological valves a2, b1 of the lower one The flow chamber is the variable-volume working chamber B of the pressure fluid motor 1 connected. Should the work chambers A and B separating pistons 4 in the direction of chamber A are moved, the electrorheological valves a1, b1 closed by applying an electrical voltage, the is called by the electrical generated in the flat columns 13 Field, the electrorheological fluid changes its viscosity from liquid to solid. The pressure side of the pump delivers the electrorheological fluid then directly over the Through hole 24 in the chamber 18. Because the valve a1 blocked is the electrorheological fluid through the Valve or the flat gaps 13 of the valve a2 in the chamber 21 is promoted and is then converted into volume Working chamber B pressed. This increases the pressure in the Working chamber B. The pressure in working chamber A remains on the other hand, at the level of the tank, since valve b2 is open is. By the pressure difference between the working chamber B and the working chamber A becomes the piston 4 towards the working chamber A moves. The electrorheological displaced from working chamber A. Liquid is passed through bore 26 into the chamber 20 pressed. Since the valve al is closed, the flows electrorheological fluid through the flat column of the valve b2 into chamber 19 and then through the through hole 25 in the tank. If the piston 4 in the direction of Working chamber B are moved, so the electrorheological Valves a2, b2 blocked and the electrorheological Valves a1, b1 de-energized and thus switched to continuity.

In an embodiment not shown, the cylinder housing provided with four flats on the outer surface, which extend over the entire axial length and each have a boundary surface of a flat gap Form valve. These are planar boundaries spaced in parallel each further as electrode surfaces trained boundary surfaces assigned to the cylinder housing flanged housing sections are formed, so that flat gap valves with flat gap surfaces are created.

Instead of using an electrorheological fluid a magnetorheological can also be used as a pressure medium Liquid are used. When using magnetorheological Liquids are used instead of the electrode surfaces electrically controllable coil arrangements are provided.

Claims (6)

Pressure medium motor based on electrorheological fluids, in which a piston guided in a cylinder housing is provided, which forms two volumetric working chambers in the cylinder housing, an inlet bore for the electrorheological fluid which is connected to a pressure medium source (pump), an outlet bore for the electrorheological fluid communicates with a tank and in the cylinder housing arranged valves based on electrorheological liquids, each having a variable-volume working chamber with the inlet bore or the outlet bore connecting valve gap, the boundary surfaces of the valve gap being designed as electrically controllable electrode surfaces, characterized in that the Boundary surfaces (7, 8, 12) on the one hand by first housing sections formed on the outer circumferential surface of the cylinder housing (2) and on the other hand by this second housing sections arranged at a distance from one another are formed. Pressure medium motor according to claim 1, wherein an annular space (9) spaced concentrically from the cylinder housing (2) arranged sleeve (6) is formed by four plastic strips (10) divided into four sub-rooms (11) and each subspace becomes a valve (a1, a2, b1, b2) forms, the boundary surfaces of the valve gap each valve (a1, a2, b1, b2) through jacket sections of the outer lateral surface (8) of the cylinder housing (2) and through jacket sections of the inner jacket surface (7) Sleeve (6) are formed. Pressure medium motor according to claim 2, wherein the subspaces (11) each valve (a1, a2, b1, b2) each through a tubular segment element (12) divided into two flat gaps (13) and the boundary surfaces of each valve (a1, a2, b1, b2) through the boundary surfaces of the tubular segment element (12) one hand and a jacket section of the inner lateral surface of the sleeve (6) or a jacket section the outer surface of the cylinder housing (2) be formed. Pressure medium motor according to one of the preceding claims, the volume-variable working chambers (A, B) each arranged on the end of the cylinder housing (2) Cover parts (15, 16) are sealed and in the Cover parts (15, 16) chambers (18, 19, 20, 21) are provided through which the valve gaps (13) of the valves (a1, a2, b1, b2) with the inlet bore (24) and the outlet bore (25) or a variable-volume working chamber (A, B) are connected. Pressure medium motor according to one of the preceding claims, the valves (a1, a2, b1, b2) as a full bridge with each other are connected. Pressure medium motor according to one of the preceding claims, using magnetorheological fluid and the valves as magnetorheological valves with coil arrangements trained to generate a magnetic field are.

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