Adjustable hydrostatic pump with additional pressure change cont

Details Adjustable hydrostatic pump with additional pressure change cont Adjustable hydrostatic pump with additional pressure change cont

1997-07-08

1999-11-09

Freay, Charles G.

Pumps

Condition responsive control of drive transmission or pump...

Adjustable cam or linkage

F04B 1100, F04B 4908

Patent

active

059802154

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention is based on an adjustable hydrostatic pump.
German Utility Model DE-GM Yt 04 126 discloses such a pump, in an embodiment as a radial piston pump, in which as the adjusting device, a cam ring is provided, whose eccentricity is considered the definitive variable for the pump adjustment or pump swiveling. The cam ring is retained in position by two different-sized hydraulic adjusting pistons, of which the larger adjusting piston is part of a hydromechanical adjusting assembly. The noise produced by such a piston pump is. very greatly dependent on the rigidity of the hydraulic fastening of the adjusting device, that is, the cam ring. The noise produced increases as the rigidity of the hydraulic fastening of the cam ring lessens and is caused by the components of the power-train forces acting in the direction of the adjustment. Depending on the rigidity of the fastening, this leads to a more or less pronounced deflection of the entire power train at the pace of the piston as it moves in and out of the pump pressure chamber. The noises that occur then may be annoying in some applications, where especially quiet operation is desired. Comparable conditions to the radial piston pump pertain to the axial piston pump as well, in which the adjusting device is embodied as a swash plate, and to a vane cell pump, which likewise has a cam ring as its adjusting device.
In a prior German patent application P 44 10 719.6, it has also already been proposed, in an adjustable radial piston pump, to provide active noise abatement, but here the adjustment of the cam ring is done via an electrohydraulic closed-loop control device. The intervention for noise abatement is done here via an electrohydraulic control valve, but many adjustable hydrostatic pumps lack such a valve.
From German patent disclosure OF 37 CO 573 A1, a radial piston engine is also known, in which an additional combustion chamber in the control journal can be charged from the high-pressure side via a throttled connection. As a function of the rotary position, the piston bore in the rotor is made to communicate briefly with this combustion chamber, and a rise in pressure is effected before this piston bore comes to communicate with the actual high-pressure control slit. In various cases, the noise reduction attendant on the lessening of the feed flow pulsation is insufficient, especially since the abrupt changes in force that occur as the piston emerges from the high-pressure side cannot be taken into account. No further description of the nature of the adjusting assembly is provided.


SUMMARY OF THE INVENTION

The adjustable hydrostatic pump of the invention, the advantage over the prior art that the noise produced by the pump is reduced substantially by lessening the influence of the components of the power-train forces that act on the hydraulic fastening of the adjusting device and counteracting them. By triggering the adjusting piston in the manner according to the invention, via an additional control unit with an additional pressure signal that is dependent on the rotary angle pf the pump, the power-train-dictated oscillations and hence the operating noise are favorably modified. This modification or reduction goes tar beyond anything that could be attained through the design of the adjusting device or of the adjusting pistons and adjusting assembly. The additional control unit for active noise abatement can be achieved using purely hydromechanical function elements, thus flaking a relatively simple, space-saving and economical design possible.
It is especially advantageous if the additional control unit is integrated with function elements that are already present anyway, so that the indicated noise reduction is attainable at very little additional expense. In this way, the requisite relative motion and the requisite synchronization already exist in the additional control unit. Especially effective noise abatement can be attained if the additional control unit controls a relief of the pressure chamber to the retur

REFERENCES:
patent: 3086477 (1963-04-01), Ruhl
patent: 4185540 (1980-01-01), Nonnonmacher et al.
patent: 4601641 (1986-07-01), Kuroyanagi et al.
patent: 4711616 (1987-12-01), Tsukahara et al.
patent: 5295797 (1994-03-01), Kahrs et al.
patent: 5391059 (1995-02-01), Hallundbaek
patent: 5651301 (1997-07-01), Thoma et al.
patent: 5752427 (1998-05-01), Leutner

Affiliated with

Also associated with

Rating

Adjustable hydrostatic pump with additional pressure change cont does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Adjustable hydrostatic pump with additional pressure change cont, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adjustable hydrostatic pump with additional pressure change cont will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1447686