Note: Descriptions are shown in the official language in which they were submitted.
543
-- 1 --
Description
Pressure Reducing Valve For
Dead Enqine Lowerin~
Technical Field
This invention relates to fluid systems and in
particular to fluid systems for controlling the raising
and lowering of a load.
Background Art
In u.S. Letters Patent 3,9~7,703 of Eugene E.
Latimer, which patent is owned by the assignee hereof,
a hydraulic control system is disclosed having a
load-lifting hydraulic motor, a source of pressurized
fluid, and a pilot-operated directional control valve
for directing fluid for operation of the motor. The
system is operative automatically upon failure of the
main fluid pressure supply to provide pressurized fluid
from the pressure side of the load-supporting motors
for emergency pilot operation of the directional
control valves.
Jesse L. Field, Jr., in U.S. Letters Patent
3,840,049, whi~h patent is also owned by the assignee
hereof, shows a control system for a fluid motor
wherein the direction control valve includes a spool
and means for selectively shifting the spool in
response to fluid pressure signals from a manually
operated pilot valve. The direction control valve
includes make-up valve means for opening a bypass
passage between the motor and the fluid return line
when necessary to prevent cavitation of the motor such
as due to an overrunning condition from the external
load.
Josef Distler shows, in U.S. Letters Patent
3,766,944, a pilot controlled fluid flow regulating
valve. The pilot valve has a body provided with inlet
~"
-- 2
means connected to a pump or other suitable source of
pressurized fluid, and port means connected to the chamber
in the housing of the regulating valve. A valve member of
the pilot valve is movable to control the flow of fluid
between the inlet means and the port means. A control
spring is mounted in the body of the pilot valve and is
deformable to displace the valve member against the
opposition of fluid pressure acting on the surface of the
valve member.
Franz Forster et al, in U. S. Letters Patent
3,698,415, show a pressure regulating valve having a
control member shiftable in a cylindrical bore of the bore
housing by a manually operable lever. A plurality of
springs are provided for interconnecting the control
member and the valve body. One of the springs comes into
play only after the control member has been displaced at
least a predetermined amount.
Disclosure of Invention
In one aspect of the present invention, a fluid
system includes an improved pressure regulating pilot
valve which permits the operator to control the movement
of the spool of the pilot valve by the operator handle so
as to control the lowering or closing of auxiliary
apparatus by the fluid motor at the control of the
operator. Concurrently with the control of the fluid
motor, pressure regulation is effected by the pilot
valve. Thus, fluid control in the fluid system is
advantageously adapted for use in controlling the
retraction of the apparatus as in the event of a dead
engine, so that the normal pressurized fluid supply is
de-energized.
543
-- 3
In the fluid system, the same spool in the
pilot valve which is utilized for providing pressure
regulated signals to the directional control valve can
be utilized in the event of a dead engine for
controlling the movement of the load as desired by the
operator. The valve operates during the dead engine
control to provide pressure regulation generally in the
same manner as during normal operation of the fluid
system.
More specifically, for example, a fluid system
may be provided having a reciprocable fluid motor,
fluid supply means including a source of pressurized
fluid, a pilot operated directional control valve for
controlling delivery of the pressurized fluid to said
motor for reciprocably operating the same, and a pilot
valve for providing the pressurized fluid to the
control valve at a predetermined regulated pressure.
The pilot valve includes an inlet port connected to the
source and an outlet port connected to the directional
control valve for conducting the pressure regulated
fluid to the control valve to controllably move the
fluid motor in one direction. The pilot valve has a
second inlet port connected to a load supporting end of
the fluid motor. A spool is movable between a first
position at which fluid from the inlet port to the
outlet port is regulated at the predetermined pressure
and a second position at which fluid from the second
inlet port to the outlet port is regulated at the
predetermined pressure. The spool is movable from its
first position to its second position only in the
absence of pressurized fluid from said source.
The pilot valve, in the illustrated embodiment
includes a spool and the means associated with the
pilot valve comprises flow passage means responsive to
movement of the spool for selectively preventing
communication between the fluid motor and the port when
the source is providing the pressurized fluid.
The valve is arranged to provide the desired
communication between the fluid motor and the port as a
result of controlled movement of the spool when the source
is not providing the pressurized fluid.
The means associated with the pilot valve
includes a manually operable actuator for selectively
positioning the pilot valve in a first disposition for
controlling regulated pressure fluid flow to the port when
the source is providing the pressurized fluid and in a
second disposition for controlling fluid flow from the
fluid motor to the port when the source is not providing
the pressurized fluid.
The valve is arranged to provide regulated
pressure fluid flow in the second disposition.
Thus, in one aspect of the fluid system, the
pressure regulating pilot valve is arranged to provide
ZO controlled fluid flow from the fluid motor of a fluid
system under dead engine conditions, while at the same
time providing pressure regulation of the fluid flow.
The present invention lends itself to simple and
economical construction while providing the highly
desirable features discussed above.
Brief Description of the Drawings
Figure lA is a sectional view of a pressure
regulating pilot valve for use in a fluid system embodying
the invention;
Figure lB is a sectional view illustrating the
connection of the control valve to the pilot valve, the
load, and the source of pressurized fluid; and
Figure 2 is a schematic diagram of the fluid
system.
~ 1~7~S9~3
Best Mode for Carrying Ou* *he Invention
In the illustrative embodiment of the inven-
tion as disclosed in the drawing, a fluid system
generally designated 10 is shown to include a pressure
regulating pilot valve 11 controlling a directional
control valve 12 for controlling delivery of pressurized
fluid from a pump 13 to a fluid motor 14. The fluid
motor illustratively may comprise a linear fluid motor
including a piston 15 reciprocable in a cylinder 16 for
lifting a load 17. A first fluid supply line 18 is
connected to one end of the cylinder and a second fluid
supply line 19 is connected to the other end. The
system includes a reservoir tank 20 and a pressure
regulating valve 21 for regulating the high pressure
output of the pump 13.
Pilot valve 11 is controlled by a manually
operable handle 22. Thus, as seen in Figure lA, the
handle is swingable about a pivot 23 so as to urge a
first actuating arm 24 against a plunger 25 and a
second actuating arm 26 against a plunger 27 of the
pilot valve. The handle is swingable within a housing
2B carried on wall means 29 defining the valve body.
Valve body 29 defines a first valve chamber
30 receiving a first movable valve member, or spool,
31, and a second valve chamber 32 receiving a second
movable valve member, or spool, 33.
Spool 31 defines an axial, downwardly opening
bore 34 communicating with an outlet port 35 connected
to a transfer conduit 36. Spool 33 defines a similar
axial bore 37 opening to an outlet port 38 connected to
a transfer conduit 39.
Valve body 29 further defines a cross bore 40
defining an inlet passage connected through a supply
conduit 41 to the pump 13.
117~ )5~3
-- 6 --
As shown in Figure lA, spool 31 is provided
with a stem 42 which extends upwardly through a con-
nector 43 into a recess 44 at the lower end of plunger
25. Similarly, spool 33 is provided with an upwardly
extending stem 45 extending through a connector 46 into
a recess 47 in the lo~er end of plunger 27. A first
coil spring 48 extends between connector 43 and a
shoulder 49 on spool 31 for biasing thé spool resiliently
- downwardly relative to the connector. Similarly, a
coil spring 50 extends between connector 46 and a
shoulder 51 on the spool 33 to bias the spool downwardly.
Connector 43 is biased upwardly by a coil
spring 52 extending between the connector and a shoulder
53 on the valve body. Similarly, a second spring 54
biases the connector 46 upwardly, spring 54 extending
between connector 46 and a shoulder 55 on the valve
body. Thus, connector 43 is normally urged against a
shoulder 56 of a plug 57 slidably carrying the plunger
25, and connector 46 is urged against a shoulder 58 on
a plug 59 slidably carrying plunger 27.
Spool 31 is provided with radial ports 60
opening to axial passage 34 and spool 33 is provided
with radial ports 61 opening to passage 37. As shown
in Figure lA, ports 60 and 61 are normally spaced from
the inlet passage 40. However, when plunger 25 or
plunger 27 is suitably depressed by manipulation of
handle 22, the corresponding connector 43 or 46 is
moved downwardly against the action of spring 52 or
spring 54 respectively, so as to permit the spools 31
and 33 to be resiliently moved downwardly by the action
of the biasing springs 48 and 50, respectively. Thus,
illustratively, when the handle 22 is swung to the left
as seen in Figure 1~, so as to depress plunger 25,
spool 31 may be moved sufficiently downwardly to provide
communication between the inlet passage 40 and the
1.~7()~3
-- 7 --
radial ports 60, thereby conducting pressurized fluid
from the pump and supply conduit 41 through ports 60
and passage 34 of spool 31, outlet 35 and transfer
conduit 36 to the directional control valve 11. The
pressure of the fluid in outlet port 35 acting on the
end of spool 31 opposes the bias of spring 48 to posi-
tion the spool 31 to a first preseIected position in
response to fluid pressure in outlet port 35. An
instantaneous preselected pressure level in outlet port
35 as established by the degree of input through handle
22 remains constant because any change of pressure in
the outlet port 35 would result in an unbalance of
force opposing the spring 48, resulting in movement of
spool 31 to open or close port 10. Thus maintaining
the force balance between spring 48 and the force
created by fluid pressure in the outlet port 35 acting
on the end of spool 31. This action provides a pressure
regulating function of the valve 10. A similar action
occurs relative to ports 61 of spool 33 so as to provide
pressure regulated fluid through transfer conduit 39 as
a function of the positioning of handle 22 in a clockwise
direction as seen in Figure lA.
As further shown in Figure lA, valve body 29
further defines an exhaust passage 62 connected through
an exhaust port 63 and a conduit 64 to the tank reservoir
20. In the retracted position of spools 31 and 33,
ports 60 and 61 thereof are in communication with the
exhaust passage so that conduits 36 and 39 are normally
vented when the handle 22 is in the neutral, centered
position of Figure lA.
Referring now more specifically to Figure lB,
directional control valve 12 defines a spool valve
having a body 65 defining a valve chamber 66 in which
is reciprocally mounted a spool 67. Conduit 36 opens
through a closure 68 into one end of the chamber 66,
and conduit 39 opens through a closure 69 into the
opposite end of the chamber.
.l.~i~7(~5~3
-- 8
Spool 67 is centered in valve chamber 66 by a
first biasing spring 70 extending between closure 68
and one end of the spool and a second biasing spring 71
extending between closure 69 and the opposite end of
the spool. A high pressure supply conduit 72 is
connected from pump 13 through the valve body 65 to an
annular recess 73 at the midportion of chamber 66. A
second annular recess 74 is spaced axially toward
closure 68 from annular recess 73 and a second annular
recess 75 is spaced axially in the opposite direction
from the recess 73. Recess 74 is connected through a
passage 76 to the fluid supply line 18 and recess 75 is
connected through a passage 77 to the fluid supply line
19 .
Outboard of annular recess 74, the valve body
is provided with an exhaust annular recess 78 and
outboard of the recess 75, the valve body is provided
with a second annular recess 79. The exhaust recesses
are connected through an exhaust passage 80 and exhaust
conduit 81 to the reservoir tank 20.
Spool 67 is provided with a first annular,
radially outwardly opening recess 82 which is in
communication with body recess 74 and spaced from body
recess 73 in the centered arrangement of the control
valve 12, as shown in Figure lB. The spool is provided
with a second annular, radially outwardly opening
recess 83 in communication with recess 75 and out of
communication with recess 73 when the spool is in the
centered position of Figure lB.
Directional control valve 12 further defines a
pair of make-up valves 84 and 85, respectively.
Make-up valve 84 is defined by a movable valve member
86 received in a valve chamber 87 in valve body 65 and
is normally biased by a spring 88 into seated relation-
ship with a valve seat 89 opening to the recess 78.
Valve member 86 defines a port 90 communicating the
passage 76 with valve chamber 87 through a passage 91.
~"
117~43
Make-up valve 85 is similar to make-up ~alve
84 and includes a valve member 92 biased by a spring 93
against a valve sea~ 94~ The valve member 92 is received
in a valve chamber 95 and is provided with a port 96.
In the normal operation of flu~d system lO,
delivery of the pressurized fluid to motor 14 is effected
by suitable movement of the spool 67 of directional
control valve 12 by selectively providing pressurized
fluid through the pilot valve ll and either of control
lO conduits 36 or 39. Thus, if it is desired to move
piston 15 of fluid motor 14 downwardly as seen in
Figure lB, suitable ~anipulation of handle 22 of the
pilot valve as shown in Figure lA, is effected to
provide pressurized fluid through the spool passage 34
to transfer conduit 36, thereby applying pressure to
the lefthand end of spool 67 of valve 12 and moving
recess 82 to the right so as to provide communiaation
between recess 73 and recess 74, thereby providing
pressurized fluid from conduit 72 through the control
valve to the supply line 18. At the same time, recess
83 is moved into communication with recess 79 so as to
provide an exhaust connection from line 19 through the
directional control valve to the exhaust conduit 81 and
tank reservoir 20.
Conversely, when it is désired to move piston
15 upwardly as seen in Figure lB, pilot control handle
22 is moved in a clockwise direction so as to provide
communication between supply passage 40 and spool
passage 37 through port 61, thereby providing pres-
surized fluid through the tran~fer conduit 39 to the
righthand end of the directional control valve and
thereby moving spool 67 to the left, positioning recess
83 so as to provide communication between recess 73 and
recess 75 of the valve body, thereby providing pres-
surized flui,d from conduit 72 through passage 77 to
1.1~7(354;~
-- 10. --
transfer conduit 19. ~t the same time, spool recess 82
is moved to provide communication between recesses 74
and 78 of the valve body to provide an exhaust passage
from conduit 18 to the exhaust conduit 81 and tank 20.
Thus, valve 11 functions as a pressure regu-
lating pilot valve for selecti~ely moving spool 67 of
directional control valve 12 as a function of the
movement of handle 22 of the pilot valve. Make-up
valves 84 and 85 are provided for effectively preventing
cavitation o~ fluid motor 14 such as when the load
forces thereon tend to cause the piston 15 to move more
rapidly than the flow of fluid from the pump 13 can
provide through the lines 18,19 . If for example, the
cylinder 14 is retracting rapidly as noted above during
a lower condition, the pressure in line 18 and passage
76 would drop. This drop in pressure is also felt in
valve chamber 87 via valve chamber 91 and port 90.
When the pressure in passage 76 drops below the tank
pressure in exhaust passage 80 and annulus 78, the
difference of pressure will act on the end of valve
member 86 liting it from its seat 89 thus providing
make-up fluid to the cylinder 16 through passage 76 and
line 18. Resultingly, fluid from conduit 19 is trans-
erred through drain passage 80 into recess 78 and,
thus, into passage 76 as a result of the unseating of
valve member 86 from seat 89 to augment the fluid flow
to the conduit 18 and, thus, effectively prevent
cavitation of motor 14.
As indicated briefly above, the improved
pressure regulating pilot valve 11 is arranged to
provide an improved means for permitting the system to
provide a controlled retraction of a load as upon the
occurrence of a failure of the high pressure fluid
supply system with the load in an extended arrangement
such as in a raised condition. The control utilizes
the pilot valve 11 to provide this desirable func-
~, tioning in a novel and simple manner.
~i7()5~
More specifical'y, as illustrated in FigurelA, pilot valve body 29 is further provided with an
annular recess 97 spaced below the inlet passage 40.
Pilot valve member 31 is provided with a recess 98
which is normally disposed between passage 40 and
recess 97 of the valve body during the normal operation
of the pilot valve in controlling the raising and
lowering of the load. A conduit 99 is connected
through a port 100 communicating with the recess 98,
and as shown in Figure lB, conduit 99 is connected to
conduit 19.
Th~s, in the event of a failure of the high
pressure pump 13 such as may result from a dead engine
condition of the vehicle in which the pilot system 10
is provided, the control system may nevertheless be
utilized to provide a controlled lowering of the load
17 through suitable manipulation of handle 22. More
specifically, under such conditions, the pressure in
the lower end of cylinder 16 is communicated through
conduit 99 and port 100 to the recess 98 of the pilot
valve spool 31. Manipulation of handle 22 in a counter-
clockwise direction as seen in Figure lA causes arm 24
to depress plunger 25 sufficiently to permit the pilot
valve to move downwardly to a position wherein recess
98 communicates between port 100 and valve body recess
97. This communication permits the high pressure fluid
from the head end of cylinder 16 to be conducted
through the port 35 and conduit 36 to the left hand end
of control valve 12, as seen in Figure lB, thereby
moving the pilot valve 67 to the right for controlling
the lowering of the load. As the pilot valve spool 31
is spring biased in this operation, reciprocal movement
of the spool 31 relative to the upper edge of recess 97
may occur so as to provide pressure regulation of the
fluid being passed from port 100 through recess 98 to
body recess 97 and discharge port 35.
,
.' ' ,.
- ~ ~.. 1.7~543
- 12 -
Thus, the pressure reducing spool 31 functions
to provide such desirable pressure regulation not only
during the normal operation of the system as when the
pump 13 is operative to provide the desired operating
pressure, but also provides desirable control and
pressure regulation in a dead engine condition wherein
the pressurized fluid of the motor 14 resulting from an
extended disposition of the load at the time of the
occurrence of the dead engine conditon is utilized to
provide pressure regulated control of the directional
control valve in a substantially similar manner so as
to provide accurate controlled lowering of the load as
well under such dead engine conditions. The same spool
that is utilized for controlling the pressure in
normal operation is utilized in controlling the pressure
and operation of the directional control valve in the
dead engine condition and, thus, a substantially simpli-
fied and economical construction of the valving system
is provided by the present invention.
The load may be any type of load desired to
be positionally controlled by such a fluid system and
while the invention is illustrated in connection with a
raised load, as will be obvious to those skilled in the
art, other forms of selectively extended loads, such as
grasping jaw loads and the like, may be suitably con-
trolled by system 10 in a like manner.
Industrial Applicability
The control system of the present invention
is advantageously adapted for a wide range of industrial
applications. Illustratively, fluid motor 14 may be
utilized in connection with a wide range of load-
displacing apparatuses. In one example, the apparatus
may comprise a loader having a bucket selectively
raised by the motor 14.
~ ,..r
- . 1 17(:)543
- 13 -
More specifically, the fluid system is advan-
tageously adapted for use in any industrtal application
where it is desired to lower a raised load controlled
by a pilot operated system in the event the pressurized
fluid source fails. The control system is utilized
with a pilot valve for controlling the directional valve
effecting the desired operation of the fluid motor and,
thus, the sytem is advantageously adapted for use with
- a wide range of apparatuses utilizing such pilot con-
trolled directional valves.
One group of apparatuses of such industrialapplications is that of earthworking vehicles generally,
one example of which is the loader discussed above.
The fluid system of the invention is advantageously
lS adapted for use with auxiliary devices associated with
such earthworking vehicles.
Other aspects, ob~ects and advantages of this
invention can be obtained from a study of the drawings,
the disclosure and the appended claims. The foregoing
disclosure of specific embodiments is illustrative of
the broad inventive concept8 comprehended by the inven-
tion.
