Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
2001-03-29
2002-04-30
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C091S433000, C192S10900B
Reexamination Certificate
active
06378557
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2000-93966 filed on Mar. 30, 2000, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure regulation valve whose output pressure variable characteristics that is changed over between pressure proportional to pilot pressure and pressure equal to supply pressure.
2. Description of Related Art
Conventionally, as shown in
FIG. 7
, is known a hydraulic circuit system having a pressure regulation valve
107
for adjusting output pressure to be applied to a hydraulic circuit
101
into control pressure proportional to pilot pressure. The hydraulic circuit
101
communicates with a hydraulic servo
100
for driving a hydraulic engagement member constituting a hydraulic multiple disk clutch (hereinafter called clutch) which serves to engage components with each other in a planetary gear device arranged between an input and output axes of a vehicle automatic transmission.
The hydraulic circuit system is provided with a pilot pressure control valve
104
driven by a solenoid valve
103
, a shift valve whose valve position is shifted upon receiving modulator pressure output from a modulator valve
105
, and a pressure regulation valve
107
for adjusting output pressure. The solenoid valve
103
is composed of a solenoid coil
131
, a coil bobbin
132
, a stator core
133
, a moving core
134
, a solenoid shaft
135
, a yoke
136
, a plate spring
137
and a cover
138
.
The pilot pressure control valve
104
has a spool
141
that is slidably housed in a valve body
110
and moves to communicate a pilot pressure conduit
111
either with a conduit
112
, to which modulator pressure from the modulator
105
is applied, or with a conduit
113
, which communicates with a drain
109
. One end of the spool
141
receives force from the solenoid valve
103
upon its operation and the other end of the spool
141
is urged in an opposite direction to which force from the solenoid valve
103
is applied by biasing force of a spring
143
whose one end is held by the other end of the spool
141
and whose another end is held by a plug
142
.
The shift valve
106
has a spool
161
that is slidably housed in the valve body
110
and serves to change the output pressure to be applied to the pressure regulation valve
107
. The spool
161
is urged in a direction opposite to receiving pilot pressure to be input into a pilot pressure feedback chamber
164
by biasing force of a spring
163
whose one end is held by a stopper
162
and whose another end is held by the spool
161
. A conduit
165
is a drain port communicating with the drain
109
. The other end of the spool
161
receives the modulator pressure through the conduit
112
.
The pressure regulation valve
107
has a spool
171
that is slidably housed in the valve body and moves so that the hydraulic circuit
101
communicates with a conduit
114
for a pressure supply source
102
or with a conduit
115
for the drain
109
. The spool
171
is urged in an opposite direction to which the pilot pressure is applied by biasing force of a spring
173
whose one end is held by the spool
171
and whose another end is held by the valve body
110
. Conduits
174
and
175
are drain ports communicating with the drain
109
. The other end of the spool
171
receives the output pressure from the shift valve
106
.
In the conventional hydraulic circuit system mentioned above, the pressure regulation valve
107
adjusts the output pressure (pressure to the clutch) either to pressure proportional to the pilot pressure at a time of clutch engagement control during which it is required to accurately control pressure to be applied to the servo
100
for driving the clutch or to higher pressure with which the clutch never slides even if higher torque is applied thereto at a time after the clutch engagement control.
In more details, according to increase of the pilot pressure input to the pilot pressure feedback chamber
164
, the spool
161
of the shift valve
106
moves toward a left side in
FIG. 7
so that the drain port
165
is opened and the output pressure of the shift valve
106
, which the other end of the spool
171
of the pressure regulation valve
107
receives, becomes zero. Accordingly, the spool
171
moves rapidly up to a left end in
FIG. 7
so that pressure equal to higher pressure from the pressure supply source
102
is applied to the hydraulic circuit
101
.
Since the conventional hydraulic circuit system has the pilot pressure control valve
104
and the shift valve
106
in addition to the pressure regulation valve
107
, an entire body thereof becomes larger.
Further, there is another conventional system having a pressure regulation valve whose pressure amplitude ratio is remarkably high so that higher pressure is secured at a time after the clutch engagement control. However, in this system, it is very difficult to accurately and precisely control the pressure to the clutch, which results in adversely affecting on driving feeling at a time of transmission stage change.
SUMMARY OF THE INVENTION
An object of the invention is to provide a compact pressure regulation valve for a hydraulic circuit in which an output pressure is accurately regulated to pressure proportional to pilot pressure at a relatively low pressure region where linear pressure control is required and to pressure directly supplied from a pressure supply source at a relatively high pressure region where maximum pressure is required.
To achieve the above object, a pressure regulation valve for a hydraulic circuit is composed of a housing having an input port to communicate with a supply pressure source, an output port to communicate with the hydraulic circuit and at least a drain port to communicate with a drain, a pilot pressure producing member supplying pilot pressure, which increases from zero to a value exceeding a given value, to the housing, a pipe shaped first spool accommodated slidably in the housing so as to receive the pilot pressure, a first biasing member giving the first spool biasing force acting in an opposite direction to receiving the pilot pressure, a feedback hydraulic chamber provided in the housing, a second spool accommodated slidably inside the first spool so as to receive the pilot pressure, and a second biasing member giving the second spool second biasing force acting in an opposite direction to receiving the pilot pressure.
With the pressure regulation valve mentioned above, the first spool is moved in the housing by first thrust force due to the pilot pressure so that the output port communicates internally with the drain port, when the pilot pressure is substantially zero, and communicates internally with the input port, when the pilot pressure exceeds the given value.
Further, the second spool is movable in the first spool by second thrust force due to the pilot pressure so that the feedback hydraulic chamber communicates internally with the output port, when the pilot pressure is below the given value, and communicates internally with the drain port, when the pilot pressure exceeds the given value.
Furthermore, the feedback hydraulic chamber gives the first spool feedback force acting in an opposite direction to which the first spool receives the pilot pressure when the feedback hydraulic chamber communicates with the output port.
The first spool moves in the housing to a position where the first thrust force balances with a sum of the first biasing force and the feedback force. When the pilot pressure is within a range from substantially zero to the given value, a normal output pressure proportional to the pilot pressure is supplied from the output port to the hydraulic circuit, since the feedback hydraulic chamber communicates with the output port and the feedback force is given to the first spool.
When the pilot pressure is in a range exceeding the given value, a maximum output pressure equal
Ando Motoyoshi
Kawamura Maki
Nakane Hiroyuki
Uno Haruhiko
Denso Corporation
Michalsky Gerald A.
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