Pumps – Condition responsive control of drive transmission or pump... – Having means to hold or resist movement of pumping element
Patent
1996-08-01
1999-03-09
Izaguirre, Ismael
Pumps
Condition responsive control of drive transmission or pump...
Having means to hold or resist movement of pumping element
4172221, F04B 4900
Patent
active
058791361
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a pump the, which can be electrohydraulically adjusted. Such pumps, in particular axial, radial piston or vane cell pumps, are known in many embodiments and are employed in many different areas of use in hydraulic engineering. In connection with this, the main advantages of the electrohydraulic adjustment of these pumps are the rapid and precise electrical controllability and the low losses of the drive constructed by means of them because of the absence of expensive valves between the pump and the consumer. In this case the control pistons of the pumps are charged with a pressure medium via a control valve. The value which is decisive for pump adjustment or pump traverse, the eccentricity of the lifting ring in connection with radial piston pumps and vane cell pumps or, in connection with axial piston pumps, the pivot angle of the swash plate, is picked up by means of a displacement transducer. This actual value signal from the displacement transducer, which is proportional to the amount conveyed by the pump, is supplied to an electronic servo amplifier and is compared there with the set value provided there. At the same time the actual value of the valve adjustment is provided via a displacement transducer to this servo amplifier, which triggers the control valve. Control of the control valve or of the pump can be provided here via an interior pressure or an exterior pressure supply.
With electrohydraulically adjustable pumps of this type the adjustment member (for example the lifting ring or the swash plate) becomes dependent on the hydraulic clamping of the adjustment manner. Noise generation increases with a falling rigidity of the hydraulic clamping and is caused by the portions of the drive gear forces acting in the direction of the adjustment. Depending on the rigidity of the clamping, this results in a more or less strong excursion of the entire drive gear in accordance with the rhythm of the pistons or chambers entering and exiting the pressure chamber of the pump.
SUMMARY OF THE INVENTION
In contrast to this, the electrohydraulically adjustable pump in accordance with the invention has the advantage that the noise generation of the pump is considerably reduced by reducing the effect of the portion of the drive gear forces acting on the hydraulic clamping of the adjustment member by counter-acting them in accordance with the applicant's invention, the control valve is controlled via the servo amplifier by an additional pulse-shaped adjustment signal which has a function of the angle of rotation of the pump. By means of the control in accordance with the invention of the control valve through an additional pulse-like adjustment signal, which is a function of the angle of rotation of the pump, the oscillations resulting from the drive gear force and thus the operating noise are favorably affected. This action or reduction goes far beyond an effect which would be possible by means of the structural design of the adjustment member or the adjustment pistons and of the layout in accordance with control technology of the position control circuit.
The additional pulse-shaped adjustment signal is formed in an advantageous manner via an rpm signal which is obtained by a conventional rpm sensor at the pump. This rpm sensor detects the passage of the pump pistons or vanes and generates an appropriate signal. This signal is supplied to a signal converter in the form of a trigger signal, which converts the trigger signal into an additional signal by means of a stored characteristic curve or a stored family of characteristic curves and provides it to the servo amplifier to form the additional adjustment signal. By means of this it is possible in an advantageous manner to generate an adjustment signal which is adapted to a defined operational behavior of the pump. It is possible to optimize an adaptation, for example to the nominal operation or to a desired operational behavior, by an appropriate selection of the characteristic curve or the family of chara
REFERENCES:
patent: 3788775 (1974-01-01), Leutner et al.
patent: 4285639 (1981-08-01), Woodring et al.
patent: 5064351 (1991-11-01), Hamey et al.
Bertsch Dieter
Leutner Volkmar
Pfuhl Berthold
Robeller Walter
Zumbraegel Joachim
Izaguirre Ismael
Robert & Bosch GmbH
Striker Michael J.
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