Motors: expansible chamber type – With motive fluid valve – Relatively movable serial valves
Patent
1997-03-26
1999-01-19
Richter, Sheldon J.
Motors: expansible chamber type
With motive fluid valve
Relatively movable serial valves
60466, F15B 1108, F15B 126, B62D 506
Patent
active
058603514
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a hydraulic steering arrangement with a steering device and an oil tank which are connected with each other via a supply line and a return line, wherein a hydraulic pump is integrated into the supply line and wherein an oil reservoir communicating with the return line and a backpressure valve, which opens in the direction toward the oil tank and is disposed between the oil tank and the oil reservoir, are provided.
DESCRIPTION OF THE PRIOR ART
If oil flows from the oil tank to the cylinder chambers of hydraulic steering arrangements, for example those of rugged, large motor vehicles, the pressure difference between the return pressure and the underpressure in the cylinder is often not sufficient to fill the cylinder chamber sufficiently rapidly with oil. A vacuum is generated by this.
As a result, knocking noises occur, particular with rapid steering changes.
In conventional circulating systems the continuous oil flow generates a certain return pressure because of throttle resistance in the return line or in the cylinder of the oil tank. The oil for filling the cylinder chambers does not come from the oil tank, instead it is diverted from the flow-through of oil.
In systems with a closed center (for example CC steering), the conditions are different. Since the oil does not flow in a continuous cycle, it is necessary for oil to flow out of the oil tank for steering in case of re-suction. If, because of flow losses, the cylinder is not sufficiently filled, knocking noises can also occur during the sudden pressure increase in the cylinder.
It is therefore the object of the instant invention to provide a hydraulic steering arrangement of the type mentioned at the outset, which avoids the mentioned disadvantages, is simply structured and operates dynamically.
SUMMARY OF THE INVENTION
This object is attained in accordance with the invention in that the oil reservoir is embodied as a piston reservoir with a piston and prestressing by means of a spring.
In this case the backpressure valve is used to provide a pressure reservoir. Because of this, oil can flow more rapidly into the underpressure chambers of the cylinder of the steering device, in particular in case of rapid steering changes or a sudden pressure rise in the cylinder of the steering device, and therefore no longer causes knocking noise.
When the storage volume of the oil reservoir in accordance with the invention is exceeded, surplus oil flows into the oil tank.
Spring prestressing is provided in this way, by means of which it is possible for the oil to reach the pressure chambers of the cylinder of the steering device better and a little faster. In the process, the backpressure valve causes the generation of back pressure in the oil reservoir against the spring.
In addition, during rapid steering movements the piston can be lifted by the oil flowing back into the oil tank only against the spring force of the spring. In the process the oil in the return line is put under pressure.
It is furthermore of advantage if the backpressure valve is integrated into the oil reservoir.
It can be provided in a further embodiment of the invention that openings toward the oil tank result after a defined travel of the piston of the oil reservoir.
This can be realized in that, for example, bores are disposed in the cylindrical wall of the piston reservoir which cooperate with the piston in the piston reservoir in such a way that the oil from the oil reservoir can flow off into the oil tank only after a defined piston travel and a pressure build-up in the return line have been reached, i.e. when the piston bottom reaches the bores.
Channels, grooves or other recesses can also be used as openings in place of bores.
Because of this embodiment in accordance with the invention, the oil reservoir is used to store the oil and simultaneously to create a pressure reservoir.
The gap between the piston and the cylindrical wall of the piston reservoir can be kept very narrow, so that the oil reaches the oil tank only slowly an
REFERENCES:
patent: 2401258 (1946-05-01), Livers
patent: 2924200 (1960-02-01), Hanna et al.
patent: 4518010 (1985-05-01), Mucheyer et al.
Knodler Helmut
Lang Armin
Leutner Wilfried
Richter Sheldon J.
ZF Friedrichshafen AG
LandOfFree
Hydraulic steering arrangement does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic steering arrangement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic steering arrangement will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1239781