Pumps – Expansible chamber type – Electrically or magnetically actuated distributor
Patent
1992-03-23
1993-11-09
Bertsch, Richard A.
Pumps
Expansible chamber type
Electrically or magnetically actuated distributor
417270, F04B 3908
Patent
active
052597385
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a fluid-driven (motor) and/or fluid-driving (pump) machine having a plurality of working chambers of cyclically changing volume and valve means to control the connection of each chamber sequentially to low-and high-pressure manifolds.
This invention has particular reference to non-compressible fluids, but its use with gases is not ruled out. It has particular reference to machines where each chamber is a piston reciprocating in a cylinder, but its use with chambers delimited by flexible diaphragms or rotary pistons is not ruled out.
SUMMARY OF THE INVENTION
The invention employs electromagnetic means to control the operation of the valve means. Using electromagnetic means opens the possibility for full electronic control with all the sophistication and precision that that makes possible.
According to the invention a fluid-working machine having a plurality of working chambers of cyclically changing volume, a high-pressure fluid manifold and a low-pressure fluid manifold, a plurality of electromagnetically controlled valves at least one such valve linking each working chamber respectively to each manifold, and sequencing means for operating the valves in timed relationship with the changing volumes of the chambers, is characterised in that each valve seals the respective chamber from the respective manifold by engagement of an annular valve part with an annular valve seat, in that a solenoid is provided to magnetically move the valve part relative to the seat by reacting with ferromagnetic material on the valve and in that at least one valve is a poppet valve having a stem and an enlarged head, the annular valve part being provided on the head and the ferromagnetic material being provided on the stem. Preferably the solenoid coil surrounds the stem and reacts with an annular piece of ferromagnetic material on the stem. Conveniently the ferromagnetic material on the stem of said at least one valve moves in the magnetic field of a permanent magnet fixed relative to the manifolds, said permanent magnet acting with the ferromagnetic material to latch the valve in a position in which the valve part is spaced from the seat or a position in which the valve part seals to the seat. Desirably the solenoid coil, permanent magnet and ferromagnetic material are all annular, the ferromagnetic material moving with the valve stem alternately into magnetic engagement with the coil and the magnet.
Preferably, energising pulses for operating the at least one solenoid are generated by a microprocessor controller receiving as input, inter alia, data relating to working chamber volume and the desired rate of working.
In a preferred arrangement, computer-controlled electromagnetic poppet valves are used to connect each cylinder of a multi-cylinder piston hydraulic motor to the associated low-pressure manifold and to the associated high-pressure manifold.
In a further arrangement a fluid-working pump is provided which has computer-controlled electromagnetic poppet valves and a "look-ahead" facility to improve the sensitivity of control.
BACKGROUND OF THE INVENTION
EP-A-0361927 describes such a pump but gives no hint as to how to solve the difficulty which comes when attempting to use the principle behind operating a fluid pump for operating a motor, namely how to open the valves against a positive pressure. To use poppet valves in a motor one must either apply a large force to them or supply carefully controlled timing pulses so that each valve only moves when the pressures on opposite sides of it are substantially equal. This specification is concerned with the latter approach in the case of the application of the invention to a motor.
The operational cycle of an hydraulic motor consists of two phases; the first is the power stroke, where the working chamber is exposed to the high-pressure manifold until it is forced to its maximum volume position. The second phase is the exhaust stroke where the valving is rearranged to connect the chamber to the low-pressure manifold and t
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patent: 3712758 (1973-01-01), Lech
patent: 4541394 (1985-09-01), Schmechter
patent: 4579145 (1986-04-01), Leiber
patent: 4763163 (1987-06-01), Kushida
patent: 5088520 (1992-02-01), Haynes
patent: 5110087 (1992-05-01), Studtmann
Rampen William H. S.
Salter Stephen H.
Bertsch Richard A.
Korytnyk Peter
University of Edinburgh
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