Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Patent
1993-01-26
1994-07-12
Michalsky, Gerald A.
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
251 3005, 251 38, F16K 31363
Patent
active
053281489
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a hydraulic piston/cylinder unit.
More particularly, it relates to a control device which has a shut-off valve with a valve body cooperating with a valve seat, and a pilot valve member arranged in the valve body and abutting against a valve seat under the action of a spring to control the pressure in a pressure space formed between the valve body and the valve housing.
Such a control device is already known from DE-OS 30 42 277. In this control device it is brought about with the aid of a fine-control shut-off valve--a so-called lowering brake valve--that the load acting on a consumer, for instance, does not proceed in advance of the pressure medium flow associated with the consumer when the load decreases. This shut-off valve has a control valve member which is guided in its valve slide. A control pin of this control valve member projects into an outlet bore hole. Such a shut-off valve has the disadvantage that pressure medium can only flow off when the control pin emerges from the outlet bore hole. The actuating path along which an adjusting device must move the shut-off valve before pressure medium can flow at all is very long.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a control device for a hydraulic piston/cylinder unit, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a control device for a hydraulic piston/cylinder unit, in which a pilot slide has a valve member and a plurality of pilot portions arranged in series, the pressure chamber is connected with the supply by two throttles arranged in series, and the pressure chamber is connectable with the discharge through the pilot slide located between the throttles and also through a passage which is opening by the pilot slide.
When the control device is designed in accordance with the present invention, it has the advantage over the prior art that the actuating paths for the shut-off valve are very short and the required actuating forces are small so that proportional magnets in particular can be used as an adjusting device for a fine control of the pressure medium flow. This is achieved by the shaping of the valve body and the construction of the pre-control or pilot slide. In particular this enables a continuous, finely controllable outflow of the pressure medium. Moreover, a stable curve of the valve characteristic over a large range is achieved as a result of the cooperation between the pilot slide and the throttle holes in the valve body. This high regulating stability of the valve results in operation with reduced vibrations so that rattling and whistling noises are also reduced. The device according to the invention is particularly suitable as a so-called lowering brake valve in which the pressure medium flowing back from the consumer (hydraulic cylinder) is throttled so that no advancing of the load or "jerking" occurs as was mentioned in the beginning.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal section through a shut-off valve in a somewhat simplified view; FIG. 2 shows a section along II--II according to FIG. 1; FIGS. 3 and 4 each show a longitudinal section through a modification of the embodiment example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 an approximately pot-shaped valve housing of a shut-off valve 10 is designated by 10A. The open end 11 of the valve housing 10A contacts a housing 12 of a proportional magnet 13. Two c
REFERENCES:
patent: 2694544 (1954-11-01), Hall
patent: 3033228 (1962-05-01), Mohler
patent: 3667722 (1972-06-01), Katz et al.
patent: 4746093 (1988-05-01), Scanderbeg
Michalsky Gerald A.
Robert & Bosch GmbH
Striker Michael J.
LandOfFree
Control device for hydraulic piston/cylinder unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control device for hydraulic piston/cylinder unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control device for hydraulic piston/cylinder unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-391418