Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2000-08-29
2002-03-19
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C251S050000, C251S052000
Reexamination Certificate
active
06357480
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pressure control valve for controlling a pressure of a fluid substance to be fed through a fluid passage or channel. Also, the present invention relates to a pressure control valve preferably for use with an automobile brake system, for example.
BACKGROUND OF THE INVENTION
Recently, a fluid pressure control system for controlling a pressure of an operating or working fluid into a predetermined value, in particular for use in an automobile brake station tends to employ a power driven pressure-source in order to provide a highly precise operational control to the automobile. Another system with an accumulator in the pressure source may be required according to a content of the control.
Specifically, for the pressure control valve system mounted in a connection between the pressure source and wheel cylinder, a highly precise pressure control is required for the wheel cylinder. For this purpose, a proportional pressure control valve system capable of controlling the fluid pressure in a precise manner according to an electric instruction tends to be employed instead of the conventional, simple switching or shutdown valves.
A majority of the conventional proportional pressure control valves employs an electromagnetic spool valve in which a spool or piston is moved to change fluid passages and/or control the open ratio of the passage. Disadvantageously, sensitive spools can move back and forth along its longitudinal direction excessively to cause vibrations. To overcome this problem and then to attain a steady-state spool valve, an improved spool valve with an orifice that defines,a fluid chamber together with the end portion of the spool is proposed in the Japanese Patent Unexamined Laid-Open; Publication JP(A) No. 4-125374, for example.
Referring to
FIG. 5
, there is shown a conventional proportional pressure control valve generally indicated by reference numeral
100
. The pressure-control valve
100
has a housing
101
with an elongated piston chamber
102
formed therein and extending vertically. The piston chamber
102
receives a piston or spool
103
therein so that the spool
103
is guided by the piston chamber
102
to move ups and downs. The housing
101
has four ports
104
-
107
each connected with the piston chamber
102
. Also, the housing
101
includes upper and lower fluid chambers
108
and
109
adjacent to the opposite, top and bottom end portions of the spool
103
, respectively. On the other hand, the spool
103
has an axial passage
110
extending from its top end positioned adjacent to the upper chamber
108
. In the vicinity of an open top end of the passage
110
, the spool
103
has a partition with a small hole or orifice
111
that connects between interior and exterior of the passage
110
. The spool
103
also has transverse holes
112
adjacent to the lower fluid chamber
109
so that the passage
110
is connected with the lower fluid chamber
109
through the holes
112
. Further, the spool
103
is formed in its outer peripheral surface with upper and lower passages
113
and
114
. The spool
103
so constructed is forced upward by a bias spring
115
and, a connecting mechanism
116
for the mechanical connection between the spool
103
and bias spring
115
, so that it sakes an elevated position (not shown) in the housing
101
.
With the arrangement, a fluid substance such as pressurized oil is supplied into the port
105
. Thee fluid flows through the lower fluid chamber
109
, transverse holes
112
and then fluid passage
110
into the upper fluid chamber
108
. As a result, the fluid pressure applies on the top surface of the piston
103
. This causes the spool
103
to move a downward direction into a lowered position shown in
FIG. 5
, which in turn allows the ports
106
and
107
to be connected to one another through the peripheral pass age
114
.
The operating fluid is then drawn from the port
104
. In this instance, the operating fluid is transported from the upper fluid chamber
108
, passage
110
, transverse hole
112
and lower fluid chamber
109
and then discharged from the port
104
, which causes the spool
103
to move upward. As a result, the passage
114
is closed and, on the other hand, another passage
113
is opened to connect between ports
106
and
107
.
The flow of the operating fluid between the fluid passage
110
and the upper fluid chamber
108
is restricted at the orifice
111
, which prevents a rapid translation of the spool
103
. This ensures a steady-state movement of the spool
103
. Also, by adjusting the size of the orifice
111
, the translation velocity of the spool
103
can be changed.
Disadvantageously, the proportional pressure-control valve system so constructed may hold air or bubbles in the fluid chambers which would cause vibrations of the spool. Typically, for removing bubbles from the upper fluid chamber
108
, the operating fluid within the housing
101
may be drawn through the ports and then exchanged with another operating fluid. However, such operation for removing bubbles can be done only when the valve system is out of operation and requires additional and complicated operations. Also, the removed bubbles may be fed back into the passages or chambers at the downward movement of the spool.
SUMMARY OF THE INVENTION
Accordingly, a pressure control valve of the present invention has housing and a piston member. The piston member is housed in the housing so that it moves between first and second positions. The housing includes a piston chamber for guiding the piston member between first and second positions while keeping a sealing engagement with the piston chamber. First and second chambers are positioned adjacent to opposite ends of the piston member so that volumes of first and second chambers are changed depending upon a movement of the piston member. First and second ports are connected when the piston member takes the first position but disconnected when the piston member takes the second position. Third port is connected with the first and second chambers but disconnected from the first and second ports when the piston member takes the first position but connected with the second port when the piston member takes the second position. A partition is defined between the first and second chambers. Also, the partition has an orifice for connecting between the first chamber and the third port.
REFERENCES:
patent: 3896856 (1975-07-01), Schumacher et al.
patent: 4821773 (1989-04-01), Herion et al.
patent: 5174338 (1992-12-01), Yokota et al.
patent: 5375506 (1994-12-01), Hashida et al.
patent: 5460199 (1995-10-01), Takata et al.
patent: 5524659 (1996-06-01), Takata et al.
patent: 5609400 (1997-03-01), Hashida
patent: 5894860 (1999-04-01), Baldauf et al.
patent: 6202697 (2001-03-01), Oyama et al.
patent: 63-208910 (1988-08-01), None
patent: 4-125374 (1992-04-01), None
English Language Abstract of JP 4-125374.
Greenblum & Bernstein P.L.C.
Michalsky Gerald A.
Sumitomo Electric Industries, LTD
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