Power steering apparatus

Details Power steering apparatus Power steering apparatus

1999-05-04

2001-01-23

Herrmann, Allan D. (Department: 3682)

Machine element or mechanism

Gearing

Follow-up mechanism

C074S422000, C074S498000, C074S60600R, C180S417000, C180S428000, C092S136000, C092S163000

Reexamination Certificate

active

06176147

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a power steering apparatus which assists steering operation by controlling supply/discharge of hydraulic fluid into/from a power cylinder using a control valve working in accordance with the steering operation.
BACKGROUND OF THE INVENTION
In a conventional power steering apparatus for vehicles, a control valve and the operation chambers of the power cylinder are connected by means of external pipes. Accordingly, there is a problem that the power steering apparatus is not easy to mount on a vehicle. Another problem is that the external pipes are sometimes damaged by sprung stones and the like. Furthermore, such piping requires an additional assembly operation, thereby decreasing productivity of the apparatus.
To overcome these problems, power steering apparatuses, in which supply/discharge flow paths for connecting the control valve with the operation chambers of the power cylinder are formed by casting, have been proposed as described in Unexamined Japanese Utility Model Publication No.Sho55-104577, Unexamined Japanese Patent Publication No. Hei7-257408, Unexamined Japanese Patent Publication No. Hei7-257409, and Unexamined Japanese Patent Publication No. Hei10-34281.
However, the above proposed apparatuses have another problem that casting is not always easy because of complex configurations of the required supply/discharge flow paths. Further, when the casing consists of a plurality of parts to be formed by casting separately, the supply/discharge flow paths should be connected during the assembly operation after casting, and thus the required assembly time is increased.
SUMMARY OF THE INVENTION
Wherefore, an object of the invention is to provide a power steering apparatus which has relatively few external pipes and can be easily assembled.
To attain this and other objects, the present invention provides a power steering apparatus comprising a casing incorporating a control valve for working in accordance with a steering operation and a power cylinder into/from which hydraulic fluid is supplied/charged in accordance with the working of the control valve, wherein: the casing comprises integrated separate sections of a valve casing in which the control valve is incorporated, a cylinder tube of the power cylinder, and a gear casing in which a steering gear is incorporated; the cylinder tube is provided with a pair of supply/discharge passages which are parallel to the axial direction of the cylinder tube and through which hydraulic fluid flows into/from the power cylinder; the gear casing is provided with a pair of connection holes communicating with the pair of supply/discharge passages; and the valve casing is provided with a pair of supply/discharge ports communicating with the pair of connection holes.
The present invention also provides the above described power steering apparatus wherein: the cylinder tube and the gear casing have respective configurations and sizes such that when matingly assembled, the pair of supply/discharge passages communicate with the pair of connection holes; and the valve casing and the gear casing have respective configurations and sizes such that when matingly assembled, the pair of connection holes communicate with the pair of supply/discharge ports.
Further, there is provided a power steering apparatus comprising a casing incorporating a control valve for working in accordance with a steering operation and a power cylinder into/from which hydraulic fluid is supplied/charged in accordance with the working of said control valve, wherein: the casing comprises integrated separate sections of a body casing and a cylinder tube; the cylinder tube is provided with a pair of supply/discharge passages, which are parallel to the axial direction of the cylinder tube, and through which hydraulic fluid flows into/from the power cylinder; the body casing is provided with a pair of supply/discharge ports of the control valve which are open in the axial direction of the cylinder tube; and the supply/discharge passages and the supply/discharge ports are connected by means of pipes.
An advantage of the invention is that when the valve casing, the gear casing, and the cylinder tube are assembled to form the casing, the pair of supply/discharge ports, the connection holes, and the supply/discharge passages communicate with each other simultaneously and thus, assembly operation is relatively easy.
Another advantage is that no use of external pipes prevents damages thereof by sprung stones and the like.
On the other hand, the minimum use of external pipes leads to still another advantage that the formation of the gear casing is relatively easy. A further advantage is that when the gear casing and the cylinder tube are assembled to form the casing, the pair of supply/discharge ports, the pipes, and the supply/discharge passages communicate with each other simultaneously and thus, assembly operation is relatively easy.


REFERENCES:
patent: 4063490 (1977-12-01), Duffy
patent: 4123965 (1978-11-01), Brown et al.
patent: 4418781 (1983-12-01), Rabe et al.
patent: 5285864 (1994-02-01), Martin et al.
patent: 5730244 (1998-03-01), Engler et al.
patent: 55-104577 (1980-07-01), None
patent: 7-257408 (1995-10-01), None
patent: 7-257409 (1995-10-01), None
patent: 10-034281 (1998-02-01), None

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