Expansible chamber devices – With fluid purifying means – Means separates gas from liquid
Patent
1996-11-25
1997-12-16
Denion, Thomas E.
Expansible chamber devices
With fluid purifying means
Means separates gas from liquid
92163, F15B 2104
Patent
active
056972873
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a hydraulic work cylinder with a piston, whose piston rod is connected with an adjusting device. The piston divides the work cylinder into pressure chambers which can be alternately charged. Line connectors for the feeding of the hydraulic oil lead into the pressure chambers.
2. Description of the Prior Art
These work cylinders are often used in connection with toothed rack power steering devices, wherein the piston rod and toothed rack are one piece which engages a pinion. Such a power steering device is known, for example, from EP 0 554 086 A2. A high degree of efficiency is expected of such a steering device, which operates with a control valve which is closed in the neutral position and whose steering circuit contains a pressure reservoir. The designer must take care that the areas of the system which are exposed to changing pressures have good ventilation. It is necessary to minimize the flexibility in the area between the entrance edge of the control valve and the work cylinder, since the pressure medium volume needed for filling the flexible area flows into the reservoir unused during the subsequent drop. A frequent cause of this flexibility is trapped air. It is therefore important that these hydraulic circuits are always operated with self-ventilation. It is possible to achieve self-ventilation of work cylinders by disposing the line connections at the top. During movement of the piston the enclosed air is then pushed out through the lines into the reservoir. However for reasons of safety and space it is often not possible to place the line connections at the top. They are therefore often found at the bottom or the sides of the work cylinder. A lateral arrangement of the line connections is shown for example in EP 0 518 922 B1 (FIGS. 1 and 2).
It is the object of the invention to create a device which makes continuous self-ventilation possible even with the line connections at the bottom of the work cylinder. This requirement should be realized without an increase in the size of the steering system and with little additional outlay.
This object is attained by the present inventions. Advantageous further developments are described in the specification.
SUMMARY OF THE INVENTION
In accordance with the main embodiments of the invention, a ring with a conduit which corresponds with the connections is located in the cross-sectional plane of the line connections in the work cylinder. This conduit is connected with the pressure chamber via inlet openings with the inlet opening located at the highest point in the work cylinder. By means of the invention the air, which has collected at the highest point of the work cylinder, is transported along in the course of a movement of the piston and is transported by means of the speed of the flow via the conduit and the lines to the reservoir. Finally, the air can be vented through the reservoir cover, which contains vents.
In accordance with a preferred embodiment, the conduit of the ring is U-shaped and is open along the exterior diameter, whereby the conduit extends over the entire circumference of the ring.
In accordance with another preferred embodiment, the ring which is open along the exterior only extends over only a portion of the circumference. The annular conduit can be easily cut and at high flow speeds its short length causes a very rapid removal of the pressure medium with the entrained air. In accordance with a variant of the invention, the ring can also be connected with a reinforcing ring of an axial seal. In that case the ring is advantageously formed in one piece on the reinforcing ring. This embodiment has the advantage of the common installation of the axial seal with the ring and easier warehousing.
Finally, in accordance with an alternate embodiment it is also possible to suspend the ring from the reinforcing ring of the axial seal by means of a snap connection.
The invention will be explained in detail by means of two exemplary embodiments represented in the d
REFERENCES:
patent: 2937502 (1960-05-01), Kenyon
patent: 5390586 (1995-02-01), Jones
Denion Thomas E.
ZF Friedrichshafen AG
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