U.S. patent number 3,718,159 [Application Number 05/108,127] was granted by the patent office on 1973-02-27 for control valve.
This patent grant is currently assigned to Hydraulic Industries, Inc.. Invention is credited to Francis H. Tennis.
United States Patent |
3,718,159 |
Tennis |
February 27, 1973 |
CONTROL VALVE
Abstract
A control valve comprising a valve element shiftable to each of
a pair of working positions to selectively communicate a service
passage with either pressure fluid supply or return passages, and
having means providing for control of the rate of fluid flow
through the service passage. The rate of flow through a selected
service passage of a sectional valve of this invention is
controlled by a pressure compensating valve mechanism in the inlet
section having a plunger which tends to move to a bypass open
position under the influence of fluid pressure at the control valve
inlet, and which tends to be moved in the bypass closing direction
under the influence of fluid pressure at the service passage. A
control passage through which service passage pressure is imposed
upon the compensating plunger includes transfer grooves in the face
of one housing section at the junction between each control section
and an adjoining housing section.
Inventors: |
Tennis; Francis H. (Oconomowoc,
WI) |
Assignee: |
Hydraulic Industries, Inc.
(Hartland, WI)
|
Family
ID: |
22320469 |
Appl.
No.: |
05/108,127 |
Filed: |
January 20, 1971 |
Current U.S.
Class: |
137/596.12 |
Current CPC
Class: |
F15B
13/02 (20130101); F15B 13/0417 (20130101); F15B
13/0403 (20130101); Y10T 137/87177 (20150401) |
Current International
Class: |
F15B
13/02 (20060101); F15B 13/04 (20060101); F15B
13/00 (20060101); F16k 011/10 () |
Field of
Search: |
;137/596.12,596.13,596.1,596.2,117 ;60/52 ;91/446 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Klinksiek; Henry T.
Assistant Examiner: Miller; Robert J.
Claims
The invention is defined by the following claims:
1. A sectional control valve comprising one or more control
sections sandwiched flatwise in a bank between end sections, one of
which provides an inlet section having inlet and exhaust passages
and a bypass through which supply fluid entering the inlet passage
can flow in bypass relation to supply passage means in the control
sections depending upon the position of an axially movable pressure
compensating plunger which regulates flow of supply fluid through
the bypass in accordance with variations in the pressure
differential across an orifice through which non-bypassed pressure
fluid is caused to flow through the supply passage means to a
service passage in one of the control sections whenever a valve
element in said control section is moved to a working position in
the bore in which the valve element operates, characterized by the
following:
A. said compensating plunger having a pair of surfaces facing in
opposite directions and upon which fluid pressure forces can be
imposed to effect movement of the plunger in one direction or the
other for regulation of flow through the bypass;
B. means for subjecting one of said surfaces to the fluid pressure
obtaining in the inlet passage;
C. and means for subjecting the other of said surfaces to the fluid
pressure obtaining in the service passage, comprising
2. a control passage extending from the inlet section to said one
control section and opening to one face of the latter at its
junction with an adjoining section,
2. a groove in the face of one of said adjoining sections at said
junction therebetween, to which said control passage opens,
3. and a hole in said one control section opening to said groove
and adapted to be communicated with said service passage by the
valve element in said working position thereof.
2. A sectional control valve comprising one or more control
sections sandwiched flatwise in a bank between end sections, one of
which provides an inlet section having inlet and exhaust passages
and a bypass through which supply fluid entering the inlet passage
can flow to the exhaust passage depending upon the position of an
axially movable pressure compensating plunger which regulates flow
of supply fluid through the bypass in accordance with variations in
the pressure differential across an orifice through which
non-bypassed pressure fluid is caused to flow through supply
passage means to a service passage in one of the control sections
whenever a valve element said control section is moved to a working
position in the bore in which the valve element operates,
characterized by the following:
A. said pressure compensating plunger regulating flow through the
bypass in accordance with change in the pressure of fluid in the
service passage when said valve element is in its said working
position, and having a pair of surfaces which face in opposite
directions and upon which fluid pressure forces can be imposed to
effect movement of the plunger in one direction or the other for
regulation of flow through the bypass;
B. means for subjecting one of said plunger surfaces to the fluid
pressure obtaining in the inlet passage;
C. and passage means by which said other plunger surface can be
subjected to the fluid pressure obtaining in said service passage,
comprising
2. communicating control passages in said control and inlet
sections opening to one face of said one control section at its
junction with an adjoining section,
2. a hole in said one control section communicable with said
service passage by the valve element in said working position
thereof,
3. and a groove in the face of one of said adjoining sections at
the junction therebetween to communicate said hole with said
registering control passages.
3. The sectional valve of claim 1, further characterized by the
following:
A. there being return passage means in the bank communicating with
the exhaust passage;
B. said control section having a pair of service passages each of
which is in turn communicated with the supply passage means while
the other is communicated with the return passage means by the
valve element in consequence of movement thereof from said one
working position to a second working position;
C. and said control section having one hole for each service
passage opening to such groove and communicable therewith by the
valve element when the element is in a working position
communicating the associated service passage with the supply
passage means.
4. The sectional valve of claim 3, further characterized by check
valve means in said holes, arranged to open to permit flow of fluid
to said groove.
5. The sectional valve of claim 3, further characterized by each of
said check valves being accommodated in a counterbore which opens
to said groove.
6. A sectional control valve having end sections and at least one
control section confined therebetween to provide a bank in which
opposite faces of the sections are in flatwise mating engagement
with similar flat faces on adjoining sections, characterized by the
following:
A. one of said end sections providing an inlet section having
therein passage means comprising fluid supply and return passages
that extend continuously through each control section;
B. each control section having
1. a service passage through which fluid may be supplied to and/or
exhausted from a fluid motor,
2. a bore with which all of said passages communicate,
3. and a valve element shiftable axially in the bore between first
and second working positions to selectively communicate the service
passage with either the supply passage or the return passage;
C. said passage means including a bypass through which pressure
fluid entering the inlet section can bypass the fluid supply
passage portions downstream thereof;
D. a pressure compensating valve mechanism in the inlet section, to
govern said bypass and operable in response to difference in fluid
pressure obtaining in the supply passage and in a service passage
which is in communication with the supply passage;
E. means for subjecting said pressure compensating valve mechanism
to the fluid pressure obtaining at the supply passage;
F. and passage means including a groove in the face of one of said
sections at each junction between a control section and an
adjoining section, for subjecting said pressure compensating valve
mechanism to the fluid pressure obtaining in a service passage
which is in communication with the supply passage.
7. A control section for a pressure compensated stacked control
valve, which control section has a housing with opposite flat
faces, a service passage through which fluid can be supplied to and
exhausted from a fluid motor, carryover passages which open to both
of said faces and which are adapted to register with corresponding
passages in adjoining sections of a stack thereof, said carry-over
passages providing pressure fluid supply and return passages, a
bore which is intersected by said passages, and an elongated valve
element slidable axially in the bore from a neutral position to a
first working position to communicate the service and supply
passages and to a second working position to communicate the
service and return passages, said control section being
characterized by the following:
A. said carryover passages including a control passage;
B. and cooperating means on the housing and on the valve element
rendered operative in said first working position of the element to
effect communication between the control and service passages, said
cooperating means comprising
1. a hole in the housing opening to the bore and to one face of the
housing,
2. and a groove in said one face of the housing, to which both the
control passage and said hole open.
8. The control section of claim 7, further characterized by the
following:
A. said fluid supply passage having a mouth which opens to said one
face of the housing at a location alongside of said groove;
B. and a circular groove in said face of the housing, encircling
the first designated groove as well as the mouth of the fluid
supply passage, to receive and hold a sealing ring in sealing
engagement with the face of an adjoining section of a stack
thereof.
9. The control section of claim 7, further characterized by the
following:
A. there being a pair of said service passages for connection with
the opposite sides of a reversible fluid motor, and communicating
with the bore at spaced zones lying at axially opposite sides of an
intermediate zone at which the fluid supply passage joins with the
bore;
B. there being a pair of said holes one for each service passage
and opening to said first designated groove and to the bore at a
location between its associated first designated zone and said
intermediate zone;
C. and the valve element being movable to said first and second
working positions to in turn communicate each service passage with
its associated hole and with the fluid supply passage, and to
communicate the non-selected service passage with the fluid return
passage.
10. In a control valve having an inlet and a valve member movable
in one direction in a bore in the body of the valve from a neutral
position to a partial operating position providing restricted
communication between a service passage and an inlet connected
supply passage through a throttle port that meters flow of supply
fluid to the service passage, the combination of:
A. a pressure compensating valve mechanism having a bypass through
which excess supply fluid entering the inlet can flow to a return
port, and having a plunger to regulate flow through the bypass in
accordance with differences in inlet and service passage pressure
to thereby maintain said metered flow to the service passage
despite change in fluid pressure therein;
B. means for effecting actuation of the plunger to a position
allowing partial flow through the bypass in response to the reduced
pressure of fluid sensed at a point downstream from the throttle
port, at which service passage pressure obtains;
C. and means rendered operative in consequence of movement of the
valve member in said direction to a full operating position, for
effecting actuation of the plunger to a bypass closing position in
response to the higher pressure of fluid sensed at a point upstream
from the throttle port, at which inlet pressure obtains.
11. The control valve of claim 10, further characterized by:
A. said valve member being movable to partial operating positions
at opposite sides of neutral to communicate either of a pair of
service passages with the return port and to restrictedly
communicate the other service passage with the supply passage
through a throttle port for said other service passage;
B. and said means for effecting actuation of the compensating
plunger to bypass closing position being rendered operative in
consequence of movement of the valve member to a full operating
position at either side of neutral.
12. A control valve having pressure fluid inlet and outlet means
and a valve element to control communication of a service passage
with fluid supply and return means, characterized by the
following;
A. means defining a feeder passage which is rendered effective by
the valve element in one operating position thereof to communicate
the service passage with the fluid supply means;
B. a load check valve in one of said passages;
C. means providing a port through which pressure fluid from the
inlet means can flow in bypass relation to the fluid supply
means;
D. a pressure compensating valve mechanism having a fluid pressure
actuatable plunger to control communication of the inlet means with
the fluid supply means and with said bypass port;
E. means for translating the pressure of fluid obtaining in the
inlet means into force on said plunger tending to move it in one
direction toward a position at which it closes off communication
between the fluid supply means and the inlet means opens up
communication between the latter and the bypass port;
F. and means for translating the pressure of fluid obtaining in one
of said passages into force on said plunger tending to move it in
the opposite direction toward a position closing off communication
between the bypass port and the inlet means and opening up
communication between the latter and the fluid supply means.
13. In combination with the control valve of claim 12:
A. another control valve having a pressure fluid inlet;
B. and means communicating the pressure fluid inlet of said other
control valve with said bypass port.
14. In combination with the control valve of claim 12:
A. said bypass port having a mouth which opens to the exterior of
the control valve;
B. and a plug closing the mouth of said bypass port.
15. A control section for a stacked control valve comprising a body
with opposite flat faces, a bore and an elongated valve element
slidable endwise therein to a working position communicating
service and supply passages which open to the bore at axially
spaced apart first and second zones, respectively, characterized by
means in the body providing for detection of the pressure of fluid
flowing to the service passage from the supply passage and
providing for imposition of said pressure upon mechanism in another
section of a sectional control valve, comprising:
A. a control passage normal to said body faces, all portions of
which are spaced from the bore and from the supply passage;
B. a passageway which is parallel to said control passage and one
end of which opens to the bore at a third zone closely adjacent to
said second zone, between it and said first zone;
C. means providing a recess in the exterior of the valve element
into which fluid leaving the supply passage initially flows on its
way to the service passage in said working position of the valve
element, said recess providing communication between the supply
passage and said one end of said passageway;
D. and passage defining means at one face of the body communicating
the other end of said passageway with the control passage.
16. A control valve having a body with pressure fluid inlet and
outlet means and a valve element to control communication of a
service passage with fluid supply and return means, characterized
by the following:
A. a pressure compensating valve mechanism having a fluid pressure
actuatable plunger which is movable back and forth in opposite
directions to control fluid flow from the inlet means to the fluid
supply means;
B. means providing a feeder passage which is rendered effective by
the valve element in one operating position thereof to communicate
the service passage with the fluid supply means;
C. the valve body having a pair of mating surfaces which are
normally maintained in intimate engagement with one another;
D. and means for translating the pressure of fluid in one of said
passages into force on the plunger tending to move it in the
direction to increase fluid flow to the fluid supply means,
comprising a passageway which is in part provided by a groove in
one of said mating surfaces.
17. In a control section for a stacked control valve having a
carryover type supply passage extending therethrough from one face
thereof to the other and intersecting a bore in which a valve
element is slidable axially from a neutral position, blocking flow
of fluid from the supply passage to a service passage, to first and
second working positions respectively communicating the service
passage with the supply passage or with a return passage via an
axial bore in the valve element, means effective in said first
working position of the valve element to provide for imposing the
pressure of supply fluid flowing to the service passage upon
mechanism in another part of the control valve, comprising:
A. a control passage in the section extending lengthwise of the
supply passage and crosswise of the bore, and having all portions
thereof spaced from the supply passage and from the bore;
B. passage means connecting with the control passage and having one
end opening to the bore at a first zone spaced from a second zone
at which the supply passage opens to the bore, the other end of
said passageway opening to one face of the section through a
counterbore which defines an annular check valve seat;
C. and means providing a recess in the exterior of the valve
element of a size to span the space between said zones and conduct
pressure fluid directly to said one end of said passage means from
the supply passage in said first working position of the valve
element.
18. The control section of claim 17, wherein said passage means
connects with the control passage through a groove in one face of
the section, opening to said counterbore.
19. In a control section for a stacked control valve having a
supply passage which opens to opposite faces of the section and
intersects a bore in which a valve element is slidable axially to
first and second working positions respectively communicating a
service passage with the supply passage or with a return passage,
means for imposing a fluid pressure force upon mechanism in another
section of a stacked control valve containing said control section,
of a value substantially corresponding to that of supply fluid in
the service passage in said first working position of the valve
element, comprising:
A. a control passage in the section extending lengthwise of the
supply passage and crosswise of the bore, and having all portions
thereof spaced from the supply passage and from the bore;
B. passage means comprising a signal passage opening to the bore at
a zone closely adjacent to the supply passage, and a groove in one
of said faces of the section connecting the signal passage with the
control passage;
C. and means on the valve element providing a recess in its
exterior through which pressure fluid leaving the supply passage
flows on its way to the service passage and through which recess
such supply fluid also enters the signal passage in said first
working position of the valve element.
20. A control valve comprising a body with a pair of bores and an
elongated valve element slidable endwise in each bore to a first
working position communicating service and supply passages which
open to its bore at axially spaced apart first and second zones,
respectively, characterized by means in the body providing for
detection of the pressure of fluid flowing to either service
passage from the supply passage and providing for imposition of
said pressure upon pressure compensating mechanism in another
portion of the control valve, comprising:
A. a control passage all portions of which are spaced from said
bores and from the supply passage;
B. a passageway for each bore, one end of which opens thereto at a
third zone closely adjacent to said second zone and between it and
said first zone;
C. means providing a recess in the exterior of each valve element
into which fluid leaving the supply passage initially flows on its
way to the service passage governed by said value element in said
working position thereof, said recess then providing communication
between the supply passage and said one end of the associated
passageway;
D. passage defining means spaced a distance from each bore and
communicating the other end of the associated passageway with the
control passage;
E. and a pair of check valves, one associated with each of said
passageways, to prevent flow of fluid thereto from the control
passage.
21. The control valve of claim 20, wherein each valve element
communicates its associated service passage with an exhaust passage
in a second working position and is further characterized by:
A. a hollow portion providing an internal passage through which
pressure fluid flows from the supply passage to its associated
service passage in said first working position of the valve
element;
B. two axially spaced holes in the wall of said hollow portion of
the valve element, one being closer to the supply passage and
serving to communicate the latter with said internal passage in
said first working position of the valve element and the other hole
communicating said internal passage with said one end of said
passageway in said first working position of the valve element;
C. and said other hole being communicable with the service passage
in the second working position of the valve element, to pass return
fluid from the service passage to the exhaust passage.
22. A control valve comprising a pair of valve elements each
movable in a bore to a working position communicating an associated
service passage with an inlet passage via a supply passage serially
connecting with said bores, and a single pressure compensating
valve mechanism having a fluid pressure responsive valve plunger to
control communication of a pressure fluid inlet with said supply
passage and with a bypass through which inlet fluid can flow in
bypass relation to the supply passage in an amount depending upon
variations in the pressure differential between inlet fluid and in
either service passage communicated therewith, characterized
by:
A. means by which the pressure of inlet fluid is translated into a
force on the plunger tending to move the same in the bypass opening
direction;
B. means by which the pressure of fluid at either service passage
is translated into an opposing force on the plunger tending to move
the same in the bypass closing direction;
C. and means on the upstream valve element for blocking the supply
passage at the bore containing said upstream valve element whenever
the latter is moved to a full working position substantially
unrestrictedly diverting pressure fluid from the supply passage to
its associated service passage.
23. A control section for a stacked control valve comprising a body
with a bore and an elongated valve element slidable endwise therein
to a working position communicating service and supply passages
which open to the bore at axially spaced apart first and second
zones, respectively, characterized by means in the body providing
for detection of the pressure of fluid flowing to the service
passage from the supply passage and providing for imposition of
said pressure upon mechanism in another section of a sectional
control valve, comprising:
A. a control passage all portions of which are spaced from the bore
and from the supply passage;
B. a passageway one end of which opens to the bore at a third zone
closely adjacent to said second zone and between it and said first
zone;
C. means providing a recess in the exterior of the valve element
into which fluid leaving the supply passage initially flows on its
way to the service passage in said working position of the valve
element, said recess providing communication between the supply
passage and said one end of said passageway;
D. passage defining means spaced a distance from the bore and
communicating the other end of said passageway with the control
passage;
E. substantially flat opposite faces on the control section to
which the supply passage and said control passage open;
F. and said passage defining means comprising a groove in one of
said faces, communicating the control passage with the other end of
said passageway.
24. A control valve having a body with pressure fluid inlet and
outlet means and a valve element to control communication of a
service passage with fluid supply and return means, characterized
by the following:
A. a pressure compensating valve mechanism having a fluid pressure
actuatable plunger which is movable back and forth in opposite
directions to control fluid flow from the inlet means to the fluid
supply means;
B. means providing a feeder passage which is rendered effective by
the valve element in one operating position thereof to communicate
the service passage with the fluid supply means;
C. the valve body having a pair of mating surfaces which are
normally maintained in intimate engagement with one another;
D. means for translating the pressure of fluid in one of said
passages into force on the plunger tending to move it in the
direction to increase fluid flow to the fluid supply means,
comprising a passageway which is in part provided by a groove in
one of said mating surfaces.
E. and a load check valve in said feeder passage.
25. In a control section for a stacked control valve having a
carryover type supply passage extending therethrough from one face
thereof to the other and intersecting a bore in which a valve
element is slidable axially from a neutral position blocking flow
of fluid from the supply passage to a service passage, to first and
second working positions respectively communicating the service
passage with the supply passage or with a return passage via an
axial bore in the valve element, means effective in said first
working position of the valve element to provide for imposing the
pressure of supply fluid flowing to the service passage upon
mechanism in another part of the control valve, comprising:
A. a control passage in the section extending lengthwise of the
supply passage and crosswise of the bore, and having all portions
thereof spaced from the supply passage and from the bore;
B. passage means connecting with the control passage and having one
end opening to the bore at a first zone spaced from a second zone
at which the supply passage opens to the bore;
C. means providing a recess in the exterior of the valve element of
a size to span the space between said zones and conduct pressure
fluid directly to said one end of said passage means from the
supply passage in said first working position of the valve
element;
D. and means on the valve element for interrupting fluid flow
through the supply passage at the bore in said first working
position of the valve element.
26. In a control section for a stacked control valve having a
supply passage which opens to opposite faces of the section and
intersects a bore in which a valve element is slidable axially to
first and second working positions respectively communicating a
service passage with the supply passage or with a return passage,
means for imposing a fluid pressure force upon mechanism in another
section of a stacked control valve containing said control section,
of a value substantially corresponding to that of supply fluid in
the service passage in said first working position of the valve
element, comprising:
A. a control passage in the section extending lengthwise of the
supply passage and crosswise of the bore, and having all portions
thereof spaced from the supply passage and from the bore;
B. passage means comprising a signal passage opening to the bore at
a zone closely adjacent to the supply passage, and a groove in one
of said faces of the section connecting the signal passage with the
control passage;
C. means on the valve element providing a recess in its exterior
through which pressure fluid leaving the supply passage flows on
its way to the service passage and through which recess such supply
fluid also enters the signal passage in said first working position
of the valve element;
D. and means on the valve element for interrupting fluid flow
through the supply passage at the bore in said first working
position of the valve element.
27. A control valve comprising a body with a bore and an elongated
valve element slidable endwise therein to a first working position
communicating service and supply passages which open to the bore at
axially spaced first and second zones, respectively characterized
by means in the body providing for detection of the pressure of
fluid flowing to the service passage from the supply passage and
providing for imposition of said pressure upon pressure
compensating mechanism in another portion of the control valve,
comprising:
A. a control passage all portions of which are spaced from the bore
and from the supply passage;
B. a passageway, one end of which opens to the bore at a third zone
closely adjacent to said second zone and between it and said first
zone;
C. means providing a recess in the exterior of the valve element
into which fluid leaving the supply passage initially flows on its
way to the service passage in said working position of the valve
element, said recess then providing communication between the
supply passage and said one end of said passageway;
D. passage defining means spaced a distance from the bore and
communicating the other end of said passageway with the control
passage;
E. said valve element communicating the service passage with an
exhaust passage in a second working position and having a hollow
portion providing an internal passage through which pressure fluid
flows from the supply passage to the service passage in said first
working position of the valve element;
F. two axially spaced holes in the wall of said hollow portion of
the valve element, one being closer to the supply passage and
serving to communicate the latter with said internal passage in
said first working position of the valve element and the other hole
communicating said internal passage with said one end of said
passageway in said first working position of the valve element, the
other of said holes being communicable with the service passage in
the second working position of the valve element, to pass return
fluid from the service passage to the exhaust passage;
G. and said holes having different diameters to effect metering of
fluid flow from the supply passage to said internal passage at one
rate and to effect metering of return fluid flow from the service
passage to the exhaust passage at a different rate.
Description
This invention relates to hydraulic control valves, and its purpose
is to provide a control valve with means to maintain the flow of
pressure fluid through a selected service passage of the valve to a
motor governed by the valve at a dependably metered rate.
In one form thereof, this invention has as an object the provision
of a hydraulic control valve with a valve element for selectively
connecting a service passage with either supply or return passage
means in the valve, and wherein first restriction means provided by
the valve element can constrain fluid to flow from the supply
passage means to the service passage at a first predetermined rate
in one working position of the valve element; and second
restriction means also provided by the valve element can constrain
fluid to flow from the service passage to the return passage means
at the same or at a different predetermined rate in another working
position of the valve element.
In another form of the invention, a pressure compensating valve
mechanism assures accurate control over the rate at which supply
fluid flows to a service passage in one working position of the
valve spool.
The operation of pressure compensating valve mechanisms is well
known. Wherever an orifice of some type is provided to throttle
fluid flow from the supply passage means to the service passage of
a control valve, pressure compensating valve mechanisms can be
advantageously employed to maintain a constant pressure drop across
the throttling orifice, and consequently thereby assure flow of
fluid to the service passage at a uniform rate regardless of
variations in the load being moved by the controlled cylinder, or
of variations in pump output pressure.
The pressure compensating mechanism embodied in the control valve
of this invention operates in a conventional manner in that it
automatically maintains such a constant pressure drop across the
throttling orifice by diverting more or less of the supply fluid
entering the valve inlet to a return passage, via a bypass governed
by the plunger of the pressure compensating valve mechanism, in
accordance with increase and/or decrease in the pressure
differential across the orifice. The plunger tends to be moved in
the bypass opening direction under the influence of fluid pressure
at the upstream side of the orifice, and it tends to be moved in
the bypass closing direction under the influence of fluid pressure
at the downstream side of the orifice. Accordingly, in a neutral or
hold position of the control valve spool, supply fluid cannot flow
through the orifice to the service passage, and there is no
pressure drop across the orifice such as occurs when pressure fluid
flows therethrough. At that time, the pressure compensating plunger
is moved to a bypass open or pump unloading position under the
influence of fluid pressure at the control valve inlet.
In general, it is another object of the invention to embody a
pressure compensating valve mechanism of the character described in
the inlet section of a sectional control valve having one or
several control sections assembled in a stack, and wherein an
exceptionally large range of throttling action is possible.
More particularly, it is a purpose of the invention to provide a
compact and low cost sectional valve mechanism in which one
pressure compensating valve mechanism can serve each of the control
sections of which the control valve is comprised.
In a more specific sense, it is the purpose of this invention to
provide a pressure compensated control valve of sectional
construction, wherein novel passage means featuring transfer
grooves in the faces of the control sections at their junctions is
relied upon to impose the fluid pressure obtaining at any selected
service passage upon the plunger of the pressure compensating valve
mechanism.
With these observations and objectives in mind, the manner in which
the invention achieves its purpose will be appreciated from the
following description and the accompanying drawings which exemplify
the invention, it being understood that such changes in the
specific apparatus disclosed herein may be made as come within the
scope of the appended claims.
The accompanying drawings illustrate several complete examples of
the physical embodiments of the invention constructed according to
the best modes so far devised for the practical application of the
principles thereof, and in which:
FIG. 1 is a side elevational view of a sectional control valve of
this invention;
FIGS. 1a and 1b are views of a portion of the valve seen in FIG. 1,
but showing modifications thereof;
FIG. 2 is a longitudinal sectional view through one of the control
sections of the valve seen in FIG. 1, taken on the line 2--2
thereof;
FIG. 2a is a view similar to FIG. 2, but showing the valve spool in
a working position;
FIGS. 2b and 2c are fragmentary sectional views illustrating
modifications of the invention;
FIG. 3 is a view taken on the line 3--3 of FIG. 1, but at an
enlarged scale, showing the seal face of one of the control
sections;
FIG. 3a diagrammatically illustrates a slightly modified embodiment
of the invention;
FIG. 3b is a fragmentary sectional view corresponding to a portion
of FIG. 2, but illustrating another embodiment of the
invention;
FIG. 4 is a cross sectional view taken on the line 4--4 of FIG. 1
and showing the compensating valve mechanism in the inlet section
of the valve;
FIG. 4a is a detail sectional view taken on the line 4a--4a in FIG.
4;
FIG. 5 is a cross sectional view similar to FIG. 4, but showing a
modification of the compensating valve mechanism;
FIG. 6 is a fragmentary view illustrating how the rate at which
pressure fluid flows to and from a fluid motor can be controlled by
the control spools of the valve; and
FIGS. 7, 7a and 7b are sectional views of another form of inlet
section for the control valve of this invention.
Referring now more particularly to the accompanying drawings, the
numeral 10 generally designates a control valve for governing the
operation of a plurality of fluid motors, such as hydraulic
cylinders (not shown). The control valve is of sectional
construction, having a number of control sections 11, 12 and 13
stacked one on top of the other to form a bank of control sections
confined between end sections 14 and 15 at the top and bottom,
respectively, of the stack.
The top section 14 provides an inlet section having a body 16 with
an inlet port 17 which is connectable with a source of fluid under
pressure, as for example, the delivery port of a pump (not shown).
In the present case, the body of the inlet section 14 also has an
outlet port 18 therein to provide for return of motor exhaust fluid
to a reservoir (not shown). It will be appreciated, however, that
the outlet port could just as well be located in the bottom section
15.
Each of the control sections comprises a housing or body 20 having
finished flat top and bottom faces 21 and 22, respectively, which
are parallel to one another, and which are disposed in flatwise
mating engagement with corresponding flat faces on the bodies of
adjacent control sections and on the end sections. As will be
discussed later, suitable seals confined between adjoining body
sections prevent leakage of pressure fluid from their
junctions.
The body of each control section is provided with a bore 24
extending lengthwise therethrough midway between its opposite faces
21 and 22, to axially slidably receive an elongated valve element
or spool 25. A supply passage 27 extends uninterruptedly from the
inlet port 17 in the top section downwardly and centrally through
all of the control sections, to intersect the bore 24 in each.
Hence, the supply passage 27 can be said to be comprised of an
inlet passage portion 17' in the inlet section, communicating
directly with the inlet port, and a supply passage portion 27' in
the body of each control section.
The supply passage portions 17' and 27' open to the flat faces of
the various body sections, and they supply pressure fluid to the
bore in each control section from whence it can be diverted by the
valve spool 25 therein to one or the other of a pair of service
passages 29-30, depending upon which direction the spool is shifted
out of its neutral position seen in FIG. 2. The service passages
open to one side of the bank of control sections and to the bore in
each control section, at opposite sides of the supply passage
portion 27' in each.
A pair of return passages 31-32 also extends down through the bank
of control sections to intersect their bores, one being adjacent to
but axially outwardly of each service passage. Thus, the return
passages can be said to comprise return passage portions 31' and
32' in each control section, which open to the opposite faces
thereof and register with the corresponding return passage portions
in adjoining control sections. The return passage portions in the
uppermost control section, of course, register with corresponding
downwardly opening return passage portions 31' and 32' in the inlet
section 14, which passage portions are internally joined with one
another by a linking passage 33.
FIG. 2 illustrates how the valve spool 25 of a control section, in
the neutral position of the spool, allows supply fluid to flow
through the supply passage portion 27' to a downstream control
section, while blocking communication between each service passage
and both its adjacent return passage portion and the supply passage
portion. When the valve spool 25 is shifted to the right out of its
neutral position, part-way toward a first working position seen in
FIG. 2a it provides limited communication between service passage
29 and the supply passage portion 27' while communicating service
passage 30 with the adjacent return passage portion 32'. The valve
spool establishes these connections or flow paths by reason of
axial passageways formed in the interior of the spool.
For that purpose, each valve spool has tubular opposite end
portions closed by a solid center section 35. The bore 36 in each
hollow end portion of the spool extends outwardly from the solid
center section 35 thereof and opens to a counterbore 37. These
counterbores are closed by plugs 38 and 39 at the opposite ends of
the spool. The plugs provide seats for coiled compression springs
40 which act upon check valves 41 and 42 in the counterbores to
normally hold the same engaged with axially outwardly facing
annular seats at the junctions of the counterbores 37 with their
respective bores 36.
Pressure fluid flowing from the supply passage portion 27' to
either service passage 29 or 30 unseats and flows past its
associated check valve 41 or 42. The check valves, of course, block
reverse flow of pressure fluid from their respective service
passages.
The inner ends of the bores 36 in each valve spool are communicated
with the bore 24 in which the spool operates through radial holes
44 and 45, in the wall of each tubular end portion of the spool. In
the hold position of the spool these holes are located between the
zone where the supply passage portion 27' and their associated
service passages 29 or 30 open to the bore 24, and so as to be
selectively registrable therewith depending upon whether the valve
spool is shifted to the right or to the left of its neutral
position seen in FIG. 2.
Other radial holes 46 in the walls of the tubular end portions on
the valve spool, located adjacent to but axially outwardly of the
check valve seats therein, are selectively communicable with their
associated return passage portions or the service passages adjacent
thereto upon shifting of the valve spool to working positions at
opposite sides of neutral. Actually, the holes 46 can be made to
have a degree of communication with the return passages in the
neutral position of the valve spool, so as to provide an easy path
for flow to the return passages of any leakage fluid from either
the service passages 29 or the supply passage 27'. This leakage
flow path can extend through either the check valves 41-42, or the
clearance along the exterior of the spool, between it and the wall
of the bore.
Hence, the bore 36 in the interior of each end portion of the spool
can conduct supply fluid to its associated service passage, or it
can conduct exhaust fluid from its service passage to the adjacent
exhaust passage portion.
If desired, each of the radial holes 44-45-46 can have a
diametrically opposite companion hole, as shown. Also, it will be
appreciated that while the control section described is intended
for the control of a double acting hydraulic cylinder, it can also
be used for single acting service. In that case, one of the service
passages would be plugged, and the other service passage would be
selectively communicable with either the supply passage portion 27'
or with the adjacent return passage portion by the valve spool.
A conventional centering spring mechanism 48 can be provided for
the valve spool described, to yieldingly resist motion thereof out
of its neutral position.
For a purpose which will appear hereinafter, the body of each
control section is also provided with a pair of pressure wells 50
and 51 which open to its bore 24 and are formed by enlargements
thereof. These pressure wells are located at opposite axial sides
of and preferably as close as possible to the zone at which supply
passage 27' joins with the bore 24. These wells are communicated
with the bores 36 in the interior of the spool through the radial
holes 44-45 in the neutral position of the spool as well as in
operating positions thereof as will be mentioned later.
When the spool is shifted to the left to a working position
establishing communication between service passage 29 and the
adjacent return passage portion 31' through the left hand radial
holes 44 and 46, communication is disrupted between the pressure
well 50 and the adjacent bore 36. At the same time, the other
pressure well 51 will be in communication with the hollow interior
of the valve spool at the right hand end thereof, at a location
directly adjacent to the zone at which pressure fluid then enters
the right hand bore 36 from the supply passage portion 27'. This
relationship between the pressure wells and the spool is reversed
when the spool is shifted to its working position to the right of
neutral.
As stated hereinbefore, the supply passage extends downwardly
through all the control sections from the inlet section 14. The
various branches or passage portions 27' of which the supply
passage is comprised open to the finished surfaces 21-22 on the
mating faces of all the body sections. The finished surface 22 on
the underside of each control section and on the inlet section is
provided with a pair of circular grooves 54 which encircle the
mouths of the return passage portions and provide for the reception
of O-ring seals 55 which are confined between the body sections at
their junctions to seal the same against leakage of pressure fluid
out of the return passages. A similar but larger diameter circular
groove 56 in the finished face on the underside of the inlet
section and each control section encircles the mouth of the
associated supply passage portion and provides for the reception of
an O-ring seal 57 which is also confined between the body sections
at their junctions to prevent leakage of high pressure fluid from
the supply passage out of the joints between body sections.
Located within the space encompassed by the large O-ring seal on
each control section, and concentric therewith, is an arcuate
transfer groove 58 which extends about two-thirds of the way around
the mouth of the supply passage portion 27'. The ends of this
groove terminate at opposite sides of the mouth of the supply
passage portion and join with holes 59 that extend upwardly into
the body to communicate the groove 58 with the pressure wells
50-51.
Also extending downwardly in the inlet section 14 and continuously
through each of the control sections is a control passage 60, which
is parallel to but offset from the supply passage 27. The control
passage is likewise comprised of registering control passage
portions in the inlet section and in each control section, and the
control passage portion in each control section opens to the medial
portion of the arcuate inner groove 58 in its control section.
Each of the body holes 59 opens to the groove 58 in the underside
of its control section through a counterbore which can receive a
ball check valve 61. The ball checks 61 provide for fluid flow into
the groove 58 and control passage 60 from the pressure wells 50 or
51, but they engage valve seats at the junction between the holes
and counterbores to block reverse flow of fluid from the control
passage into the body holes 59.
The purpose of the control passage, the groove 58, holes 59 and
pressure wells 50 and 51 is to provide for subjection of a pressure
compensating valve mechanism 62 in the inlet section 14 to the
pressure of fluid obtaining at any service passage which is
receiving pressure fluid from the supply passage.
The pressure compensating valve mechanism 62 comprises an elongated
pressure sensitive plunger 63 which is slidable endwise in a bore
64 in the inlet section 14 with its axis parallel to those of the
valve spools. Plugs 65 and 66 close the opposite ends of the bore
and also define the limits of sliding motion of the plunger. The
plunger is normally held engaged with the plug 66, at its right
hand limit of motion, by a coiled compression spring 67 having one
end bearing against the other plug 65 and its opposite end portion
received in a well 68 in the adjacent end of the plunger. In that
position, the plunger closes a bypass between the inlet passage
portion 17' and the outlet passage portion 31'.
The bypass is provided by two short portions 69 and 70 of the bore
64, which lie at opposite sides of the junction of the bore and the
inlet passage portion 17'. Hence, the inlet of the bypass is
jointly provided by the adjacent ends of the bore portions 69-70.
The outlet of the bypass is jointly defined by the remote ends of
the bore portions 69-70, which open to the junctions between the
bore 64 and the return passage portions 31'-32'.
The land provided by the left end portion of the plunger 63 is
normally engaged in the bore portion 69, and it cooperates with a
short medial land 71 on the plunger which is normally engaged in
the bore portion 70 to close the bypass. A radial hole 72 in the
land 71 at all times communicates the inlet passage 17' with a
pressure chamber 73 through an axial passage 74 in the right hand
end portion of the plunger. The pressure chamber 73 comprises an
enlargement of the bore 64 just inwardly of the plug 66, and fluid
therein will always be at a pressure value corresponding to that of
fluid at the inlet port 17 and the supply passage.
The right hand end of the plunger projects into the chamber 73 and
pressure fluid therein acts upon the plunger tending to move it to
the left, to a bypass open or pump unloading position whenever
there is no countering pressure on the plunger to oppose such
movement thereof out of its bypass closing position.
For example, the plunger will be moved to its bypass open position
whenever all the valve spools are in their neutral positions, to
then allow all the pump fluid entering the inlet 17 to flow through
the bypass comprising bore portions 69 and 70, for return to the
tank.
Only part of the fluid entering the supply passage is bypassed to
the outlet, however, if a valve spool 25 in one of the control
sections is then moved to the right to a working position causing a
metered amount of pressure fluid to flow from the supply passage
portion 27' therein to service passage 29 via the left-hand bore
36. Such flow can be metered through the orifice or throttle
provided by limiting communication between the supply passage
portion 27' and the hollow interior of the valve spool through the
radial holes 44. Accordingly, supply fluid will enter the interior
of the spool from the holes 44 at reduced pressure, which pressure
will reflect the load on a fluid motor supplied from service
passage 29. Such reduced pressure is also manifested in the
pressure well 50, and is accordingly impressed upon the left-hand
end of the compensating plunger where it will counteract the bypass
opening force exerted thereon by fluid at inlet pressure. As a
result, the plunger will seek a balanced position at which the
bypass is only partially open, and at which position it will be
maintained by the fluid pressure forces acting upon its opposite
end portions as long as the position of the valve spool remains
unchanged.
The pressure of fluid entering either hollow end portion of the
valve spool for flow to the selected service passage will also be
manifested in one or the other of the pressure chambers 50 or 51
and in their respective body holes 59, and hence in the groove 58
with which said holes communicate. This results from the fact that
in either working position of the spool, that radial port 44 or 45
which communicates with the supply passage will also be disposed to
communicate with its associated pressure well and body hole 59, and
through the latter, with the groove 58 in the underside of the
body.
The pressure obtaining in the groove 58 will also be manifested in
the control passage 60, which leads back to the inlet section 14 to
communicate with a control passage branch 76. The branch 76
connects with a pressure chamber 77 through a damping check valve
78. The pressure chamber 77 comprises an enlargement of the bore 64
at the left hand end thereof, and the corresponding end of the
pressure compensating plunger 63 extends into it so that pressure
fluid in the chamber can exert force on the plunger tending to move
it in the same direction as its spring 67, namely, in the bypass
closing direction.
From this, it will be seen that one end of the compensating plunger
is always subjected to the force of pressure fluid obtaining at the
valve inlet, while the other end of the plunger will be subjected
to the opposing force of pressure fluid obtaining in the service
passage to which pressure fluid is directed by a selected one of
the valve spools in the bank of control sections. Since the
pressure in the selected service passage will vary with the load on
the hydraulic cylinder supplied therefrom, any change in the load
will result in a corresponding change in pressure in the service
passage and also in the chamber 77 of the pressure compensating
valve mechanism. As a result, the pressure compensating plunger
will be moved to the right, to effect a corresponding increase in
the pressure of fluid flowing to the service passage if the load on
the cylinder increases; and it will be moved to the left, to effect
a corresponding reduction in the pressure of fluid flowing to the
service passage if the load on the cylinder decreases.
In either case, plunger movement will be arrested when a
predetermined pressure drop corresponding to the desired rate of
fluid flow to the cylinder exists across the orifice through which
pressure fluid enters the hollow interior of the spool on its way
to the selected service passage. As stated, this orifice can be one
arbitrarily determined by an operator in actuating a selected one
of the valve spools to a metering position displaced from neutral
somewhat less than the spool travel needed to reach a full speed
operating position. Hence, the orifice is determined by the degree
of communication between the supply passage and one of the radial
holes 44 or 45 in the selected valve spool.
When pressure fluid is flowing through such an orifice to one of
the service passages, the pressure at the downstream side of the
orifice will always be less than that at its upstream side. If the
load increases, the pressure differential across the orifice
decreases correspondingly and the pressure compensating plunger
responds by moving in the bypass closing direction by whatever
amount is necessary to restore the desired pressure differential
across the orifice. Similarily, the plunger will respond to an
increase in the pressure difference at opposite sides of the
orifice, resulting from a decrease in the load on the cylinder, by
moving in the bypass opening direction to increase the amount of
supply fluid bypassing the supply passage by whatever amount is
necessary to restore the desired pressure drop across the
orifice.
The pressure compensating valve mechanism thus operates to maintain
movement of the work performing element of a hydraulic cylinder
governed by the control valve at a uniform speed. It is important
to note, however, that the load pressure is sensed in the wells
50-51, at locations close to the downstream side of the orifice
through which pressure fluid enters the interior of the valve spool
for flow to the selected service passage, and hence at a location
upstream from the load holding check valve past which the fluid
must flow before entering the service passage. Accordingly, the
check valve and its spring, and any line pressure losses downstream
from the pressure wells 50-51, are then treated as part of the load
by the compensating valve mechanism, for more accurate control over
the speed of motor operation.
In instances where limited flow of supply fluid to all the
hydraulic motors governed by the control sections is essential, one
common orifice can be provided for the entire bank of control
sections. In that case, the orifice can comprise a hole in a
metering washer 80 confined in the junction between the inlet
section 14 and the adjacent control section 11, as seen in FIG. 1a.
The washer can be seated in a shallow counterbore in the underside
of the inlet section, inside the central larger diameter O-ring,
and the hole in the washer registers with the mouth of the supply
passage portion 27' in the adjacent control section 11.
It will also be apparent that such an orifice washer can be
confined in the supply passage 27' between any two control
sections, to meter flow of supply fluid to the control sections
downstream therefrom. In that case, the washer would be
accommodated in a well in the top face of one of the control
sections, as in FIG. 1b.
The inlet section 14 can also be provided with a relief valve
mechanism 85, which opens to relieve to the outlet 18 excessive
pressure in chamber 77 of the pressure compensating mechanism.
In the construction described, the ball checks 61 can close against
their respective seats to assure that high pressure fluid will flow
to a selected service passage for high pressure requirement in the
event a plurality of valve spools are in working positions at the
same time. On the other hand, if the balls are left out of one of
the valve sections, as for example, the control section 13,
assurance will then be had of fluid flow to a selected service
passage in said section for a low pressure requirement, which then
has priority over motors governed by the other valve spools
operating at higher pressures.
FIG. 3a diagrammatically indicates how the transfer groove 158 in
the underside of each control section can communicate the pressure
wells 50-51 with the control passage 60 through a single check
valve 161 for each groove. However, instead of having external
transfer grooves 58, 158 formed in the faces of the valve sections,
the pressure wells 50-51 can be communicated with the control
passage 60 by an internal bridge 258, and a single check valve 161
through which the bridge connects with the control passage, as seen
in FIG. 3b.
FIG. 5 depicts a slightly different form of pressure compensating
valve that can be incorporated in the inlet section 14 when quick
response of the compensating plunger to its pump unloading position
is desired. For example, if the inlet 17 is connected to the high
pressure carryover port of an upstream control valve, the plunger
163 will remain in its closed position as long as the spool of the
upstream valve is in a full operating position. When that control
spool is returned to neutral, however, full pump pressure is
suddenly imposed at the inlet 17, and an undesirably high shock
pressure would result except for the fact that means is provided to
effect quick opening of the plunger 163.
For that purpose, the hollow left hand end of the plunger 163 has a
small vent 90 in the side wall thereof, opening into the adjacent
portion 31' of the outlet passage, to vent the bottom portion of
the well. A small plunger 92 is also slidably received in the well
68 of the main plunger 163, ahead of the vent 90; and a reduced
stem 93 on the smaller plunger projects out of the mouth of the
well into the interior of the spring 67. In this case, the spring
67 bears against a washer 94 which encircles the step 93 and is
urged by the spring toward engagement with the adjacent end of the
pressure compensating plunger 163. The smaller plunger 92 is
yieldingly urged axially outwardly toward the spring 67 by a coiled
compression spring 95 confined between the plunger and the bottom
of the wall 68. The spring 95 yieldingly holds the smaller plunger
in an outer position defined by the engagement of the shoulder 96
at the base of its stem with the washer 94.
With this arrangement, the pressure of fluid flowing out of a
selected service passage to a fluid motor is imposed upon the left
hand end of pressure compensating plunger 163 through washer 94,
thereby tending to move the plunger to the right, in opposition to
the force which fluid at inlet pressure exerts upon its right hand
end. Hence, with the compensating plunger in either a partial
bypass position or in a full feed position preventing bypass of
inlet fluid to the outlet, actuation of the upstream control valve
to bring pump fluid at full pressure into the inlet 17 will result
in rapid movement of the compensating plunger to the left, to its
bypass open position, in response to the force which pressure fluid
in the inlet exerts upon its right hand end.
Such rapid movement of the compensating plunger is assured by
reason of the fact that the fluid displaced thereby as it begins to
move to the left, acts upon the outer end portion of the smaller
plunger 92 and forces the same inwardly into the well 68 to make
room for the displaced fluid in the resulting space ahead of the
smaller plunger. The vent 90, of course allows for substantially
free movement of the smaller plunger 92 into the well.
FIG. 6 illustrates how a valve spool 263, like those previously
described, can be modified to allow the spool to be shifted to full
first and second working positions and still provide for flow of
fluid to and from a service passage governed thereby at the same or
at different metered rates. This is in contrast to that form of the
invention described hereinbefore, where metered flow of fluid to a
service passage was possible only by actuation of the valve spool a
distance somewhat short of its full working position.
Only the left hand half of one of the control sections has been
shown in FIG. 6, along with its supply passage portion 27', and the
corresponding service and exhaust passages 29 and 31',
respectively, therein. In this case, the spool 263 has three
axially spaced radial holes in the wall of its hollow end portion,
numbered 98, 99 and 46, reading to the left from the solid center
section 35 of the spool. As before, the hole 46 is located axially
outwardly of the seat for check valve 41; and the two holes 93 and
99 are located between the check valve seat and the solid center
section of the spool, with the hole 99 closer to the check
valve.
The hole 98 is located to be brought into register with the supply
passage portion 27' when the valve spool is shifted to a full
working position to the right of its neutral position shown, at
which time its companion hole 99 will register with the pressure
chamber 50, and the third hole 46 will align with the service
passage 29. Hence supply fluid can flow from passage 27', through
the metering orifice provided by hole 98, to the interior of the
spool and past the check valve to service passage 29. The pressure
of fluid at the downstream side of the orifice provided by hole 98,
of course, is manifested in chamber 50, and also through the
arcuate groove 58 in the underside of the control section body, in
the control passage 60 for the compensating valve mechanism.
The rate at which fluid flows to the motor is thus dependent upon
the size of the hole 98, and its diameter can be predetermined in
accordance with the speed of operation desired for the fluid motor
governed by the valve spool. Accordingly, with a hole 98 of given
size, a load may be raised at the desired rate by the fluid motor
with the spool shifted to a full working position to the right of
neutral. The same load can be lowered at the same rate, or at
either a faster or slower rate, if desired. The descent of the load
is governed by the size of the radial hole 99 in the valve spool,
which is brought into register with the service passage 29 when the
spool is shifted to a full working position to the left of its
neutral position shown. At that time fluid returning to the service
passage flows to the exhaust passage 31' through hole 99, the check
valve 41 and hole 46.
FIG. 2b illustrates how this invention can be embodied in a control
valve similar to that seen in FIG. 1, but having one or more
control sections of the series-parallel or so-called priority type.
As therein seen, the center section 112 is provided with a
series-parallel type valve member 125 which is again slidable
axially in its bore 24 to a pair of working positions at opposite
sides of a neutral position shown. The control section 112 is also
provided with a typical series-parallel type of carryover supply
passage comprising a pair of inlet or upstream branches 127-227
which communicate with the bore 24 at axially spaced zones and have
a common inlet portion in register with the supply passage 27' in
the control section 11. The supply passage in the control section
112 also includes a single downstream branch 327 which communicates
with the bore 24 at a location medially between the branches
127-227, and registers with the supply passage portion in the
downstream control section 13 in the usual way.
The valve member 125 has two grooves 101-102 therein located at
opposite axial sides of a narrow central land 103. These grooves
communicate the downstream branch 327 of the supply passage with
the supply passage portion 27' in control section 11 through both
of the upstream branches 127-227 in the neutral position of the
valve member 125.
With the construction described, the grooves 101 and 102 have an
axial length such that the downstream branch 327 of control section
112 will be closed off from both upstream branches 127-227 in each
working position of the valve member 125, so that flow of supply
fluid to the downstream control section 13 will be prevented. It
will be understood, of course, that one or the other of the
pressure chambers 50-51 will be communicated with its respective
service passage, depending upon which of its two operating
positions the valve member is shifted to, so as to again cooperate
with the body holes 59, arcuate groove 58 and control passage 60
(not shown) in imposing the pressure of fluid in the selected
service passage on the plunger of the compensating valve mechanism
in the inlet section of the valve bank.
As before, the pilot fluid pressure for augmenting the force of
spring 67 upon the compensating plunger is sensed at a location
upstream from the check valve 41 through which supply fluid is
flowing to the selected service passage. This is highly desirable
inasmuch as pressure losses through the check valves or at any
location downstream from the throttle ports 44-45 will not affect
flow to the work ports; and it helps to eliminate pulsing feed back
signals from the work ports to the control passage 60, which could
otherwise have an unstabilizing effect upon the plunger 63 of the
compensating valve mechanism.
In certain cases, it may be desirable to assure flow to a selected
service passage of all of the pump fluid entering the inlet 17 of
the control valve. For that purpose, a valve member 225 such as
shown in FIG. 2c can be embodied in a selected one (or more) of the
control sections, for example in the section 12.
The valve member 225 has a central circumferential groove 105 in
its exterior which can be brought into registry with one or the
other of the pressure wells 50-51 when the valve member is shifted
to a full working position at either side of neutral. As seen in
FIG. 2c, the valve member has been shifted to the right, to a
working position at which the radial hole 44 no longer throttles
flow to its associated service passage, and the external groove 105
establishes communication between the supply passage 27' and
pressure chamber 51. Chamber 51, of course, is communicated with
the pressure chamber 77 of the pilot valve mechanism in the inlet
section seen in FIG. 4, through the body hole connecting with
chamber 51, the face groove 58 and control passage 60, as described
hereinbefore.
Thus, the left hand end of the compensating plunger 63 will be
subjected to the pressure of fluid obtaining in the supply passage
27' whereas with the embodiment of the invention initially
described, it was subjected to reduced pressure obtaining in one or
the other of the bores 36 in the hollow end portions of the valve
member. In other words, both ends of the compensating plunger will
then be subjected to the pressure of fluid obtaining in the supply
passage 27, and the spring 67 acting thereon will move the plunger
to its right hand limit of motion to completely close the bypass in
the inlet section 11. All pressure fluid then entering the inlet 17
will be constrained to flow to the service passage served by the
radial hole 44 in the valve member 225.
This contrasts with the embodiment of the invention described
initially, wherein the compensating plunger 63 was subjected to a
bypass closing force limited in accordance with the reduced fluid
pressure obtaining in one or the other of the hollow end portions
of the actuated valve member, after flow of pressure fluid from the
supply passage through the throttle port provided by the associated
radial hole 44 or 45. In the FIG. 2c embodiment, of course, the
groove 105 in the exterior of the valve member has the effect of
bypassing that throttle port 44 which is in communication with the
supply passage 27' and the pressure chamber 50, and of directly
communicating the other pressure chamber 51 with the supply
passage.
If at such a time the fluid pressure in that end portion of the
valve member to which fluid is flowing from the throttle port 44
should be less than that obtaining in the supply passage, the small
ball check in the body hole 59 connecting with the pressure chamber
50 will close under the influence of the greater pressure in the
other pressure chamber 51, to assure that full supply pressure will
be available to act on the compensating plunger and move it to its
bypass closing position.
FIGS. 7, 7a and 7b illustrate another form of pressure compensating
inlet section 140 which can be used to considerable advantage in
place of the inlet section 14 shown in FIG. 1; and in which case
the outlet section 15 is provided with a passageway (not shown) to
communicate the return passages 31 and 32 with one another.
The inlet section 140 has a compensating valve spool 107 which is
axially slidable in a bore 64, and the spool has a land 108 formed
between two circumferential grooves 109 and 110. The spool is
normally urged toward its right hand limit of motion engaging plug
66, by means of a spring 67.
As before, the position of the compensating spool in bore 64 during
use, is determined by the force of spring 67 and by the fluid
pressures obtaining in chambers 77 and 73, at the left and right
hand ends, respectively, of the bore. The pressure in chamber 77,
of course, mirrors the load pressure as hereinbefore explained;
while the chamber 73 is pressurized by pump fluid from the inlet
17.
In this case, however, the inlet 17 does not have direct
communication with the supply passage 27. It and the supply passage
open to the bore 64 at axially spaced zones and are communicable
with one another through the spool groove 109. However, the land
108 on the spool closes off such communication of the inlet with
the supply passage when the spool is in its left hand limit of
motion defined by plug 65. Also, the axial passage 74 in the
compensating spool is normally in communication with the inlet 17
through a radial hole 72 which opens to the spool groove 109.
One of the features of the inlet section 140 is that it is provided
with a bypass port 130 that can be used either as a pump unloading
bypass which opens directly to the exterior of the inlet section
for connection with a reservoir line (not shown) or as a power
beyond port. The bypass port 130 opens to the bore 64 at a location
between the pressure chamber 73 and the junction between the bore
and the inlet 17, and it is communicable with the inlet upon
shifting of the spool to the left (by pump fluid in chamber 73) a
distance sufficient to allow inlet fluid to pass into the spool
groove 110. Consequently, it can be said that the land 108 provides
for selectively communicating the inlet port 17 with either the
supply passage 27 or the bypass port 130, depending upon the axial
position of the compensating spool 107.
FIG. 7a more or less diagrammatically illustrates how another
control valve 131 for a hydraulic cylinder 132 can be supplied with
pump fluid from the bypass port 130 of inlet section 140 via a
power beyond supply line 133 at times when the valve elements in
the control sections 11, 12 and 13 are in their neutral positions.
Since there is then no demand for pressure fluid on the part of any
of the control sections 11, 12 and 13, pump output fluid in the
inlet port 17 pressurizes chamber 73 sufficiently to shift the
compensating spool 107 to the left, to close off the supply passage
27 from the inlet port and to communicate the latter with the
bypass port 130. Accordingly, port 130 then becomes a power beyond
port, and pump fluid is made available for flow to either end of
the hydraulic cylinder 132, depending upon the direction in which
the valve element 134 of its control valve 131 is shifted out of
neutral.
It is important to note, however, that the fluid motors governed by
the control sections 11, 12 and 13 will have priority over the
cylinder 132. This is to say that if the valve element of either
control section 11, 12 or 13 is shifted to an operating position,
the resulting load pressure manifested in chamber 77 of the inlet
section 140 will cause the compensating spool 107 to be moved to a
position at which its land 108 closes off the power beyond port 130
from the inlet 17 and affords communication between the latter and
the supply passage 27. No pressure fluid can then flow to the
cylinder 132 from the power beyond port 130, even through the valve
element 134 of its control valve were to be shifted to one or the
other of its operating positions.
If the bypass port 130 is connected to the reservoir of the system,
instead of to the inlet of a control valve as in FIG. 7a, the port
130 becomes the full equivalent of the return passage portion 32'
of the FIG. 4 embodiment.
While the convertibility of the port 130 from bypass to power
beyond enhances the versatility of the inlet section 140, it can
have still greater utility if the mouth of that port, at the
exterior of of the section, is closed by a plug 135, as seen in
FIG. 7b. In that case, the control valve bank on which the inlet
section is installed is effectively converted for closed center
operation.
From the foregoing description, together with the accompanying
drawings, it will be apparent to those skilled in the art that this
invention provides an exceptionally simple hydraulic control valve
which is particularly well suited for use on hydraulically operated
equipment where the rates of fluid flow to the governed hydraulic
motors must be closely regulated.
Those skilled in the art will appreciate that the invention can be
embodied in forms other than as herein disclosed for purposes for
illustration.
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