Fluid handling – Systems – Multi-way valve unit
Patent
1997-09-16
1999-04-27
Michalsky, Gerald A.
Fluid handling
Systems
Multi-way valve unit
13762564, F15B 13043
Patent
active
058968903
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention generally relates to hydraulic servo valves and specifically to a pilot-operated servo valve with four main- stream ports for mounting into a control block.
Pilot-operated electrohydraulic servo valves of twin- and multi-stage design with four main-stream ports are used as 4-way valves to control the position, speed and force in cylinders for linear movements or position, rotational speed and torque in hydraulic motors for rotary movements.
They are conventionally designed as plate-stack valves, i.e. they have a prismatic valve housing for mounting on a connection surface of a hydraulic block. The four main-stream ports of the valve lie in a planar connection surface of the valve housing, and their openings into the control bore of a main control piston are designed symmetrically. Control chambers are arranged in end caps flange-mounted on the valve housing on both sides. These control chambers are connected via control bores to a pilot servo valve. The symmetrical main control piston is hydraulically actuated by applying pressure to its two end surfaces in the end control chambers. Pilot-operated 4-way servo valves with valve housing for mounting on a connection surface of a hydraulic block are highly space-consuming and require complicated bores in the hydraulic block for the four main-stream ports.
Prior art pilot-operated 4-way servo valves have a spring-centered rest position. In most cases the main control piston is centered via two opposite return springs arranged in the end control chambers and acting against each other.
A pilot-operated 4-way proportional valve with one-sided spring centering is described in the German hydraulic handbook "Der Hydraulik Trainer Band 2", published by Mannesmann Rexroth GmbH, DE-8770 Lohr am Main (Germany), 3rd edition 1989, page 31, FIG. 33. The disclosed valve is conceived for mounting on a connection surface of a hydraulic block. The control chambers of the valve are disposed in end caps, which are flange-mounted on opposite sides of a valve body. DE-A-4011908 discloses a 5-way valve with one-sided spring centering and an actuating piston disposed at the opposite end of the main control piston. This valve too is conceived for mounting on a connection surface of a hydraulic block.
SUMMARY OF THE INVENTION
The invention provides a pilot-operated servo valve which can be integrated in a space-saving manner in a hydraulic block, has a clearly defined center position and good dynamic properties.
The pilot-operated 4-way servo valve according to the invention has a control sleeve, which can be mounted directly in a stepped bore in a hydraulic block. This control sleeve has axially spaced lateral openings for first, second and third lateral working connections in the hydraulic block. The hydraulic block into which the control sleeve is inserted has three lateral block bores for the first, second and third main-stream ports. The opening into the control sleeve for the fourth main-stream port is arranged on the front end of the control sleeve in such a way that this fourth main-stream port terminates axially in the control sleeve. This control sleeve provides great freedom with regard to the arrangement of the block bore for the fourth main-stream port. The latter can be disposed, for example, in a direct axial extension of the stepped bore for the control sleeve. Furthermore, with the pilot-operated 4-way servo valve according to the invention, the need for bridgings in the hydraulic block between individual main-stream ports is eliminated. The servo valve according to the invention thus affords a far more compact construction of the control blocks than is possible with conventional servo valves. Even in more complex hydraulic control systems the servo valve according to the invention can be integrated together with various additional valves, e.g. two-way built-in valves, in a space-saving manner into a hydraulic block. Direct mounting in the cylinder cover of larger cylinders is likewise possible.
The main control piston of t
REFERENCES:
patent: 5445188 (1995-08-01), Bourkel et al.
Bourkel Arsene
Lanfermann Bernd
Post Karl-Heinz
Tratberger Karl
Hydrolux S.a r.l.
Michalsky Gerald A.
Nath Gary M.
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