U.S. patent number 3,759,292 [Application Number 05/207,028] was granted by the patent office on 1973-09-18 for hydraulic control valve assembly.
This patent grant is currently assigned to Caterpillar Tractor Co.. Invention is credited to Donald L. Bianchetta, Kenneth R. Lohbauer.
United States Patent |
3,759,292 |
Bianchetta , et al. |
September 18, 1973 |
HYDRAULIC CONTROL VALVE ASSEMBLY
Abstract
A valve assembly comprising a plurality of distributor valves
for operation of a plurality of hydraulic motors is provided with a
plurality of inlets for a plurality of supply sources. The
distributors are interconnected so that the implements may be
operated by separate sources or the sources combined for selective
operation of certain implements.
Inventors: |
Bianchetta; Donald L. (Coal
City, IL), Lohbauer; Kenneth R. (Joliet, IL) |
Assignee: |
Caterpillar Tractor Co.
(Peoria, IL)
|
Family
ID: |
22768912 |
Appl.
No.: |
05/207,028 |
Filed: |
December 13, 1971 |
Current U.S.
Class: |
137/596;
60/325 |
Current CPC
Class: |
F15B
13/08 (20130101); E02F 9/2296 (20130101); E02F
9/2239 (20130101); E02F 9/2292 (20130101); F15B
11/17 (20130101); F15B 2211/355 (20130101); F15B
2211/3116 (20130101); F15B 2211/20553 (20130101); F15B
2211/763 (20130101); Y10T 137/87169 (20150401); F15B
2211/30595 (20130101); F15B 2211/20576 (20130101) |
Current International
Class: |
E02F
9/22 (20060101); F15B 11/00 (20060101); F15B
13/00 (20060101); F15B 13/08 (20060101); F15B
11/17 (20060101); F15b 013/06 (); F16k 011/07 ();
F15b 011/00 () |
Field of
Search: |
;137/596,596.13,596.12,597,625.2,625.4,614 ;91/414,6,413
;60/52HE |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Klinksiek; Henry T.
Assistant Examiner: Miller; Robert J.
Claims
We claim:
1. A control valve, said valve comprising:
a housing having a cylindrical bore formed therein;
a first inlet passageway communicating with the center of said
bore;
an outlet passageway communicating with said bore adjacent the
communication of said inlet passage and communicating along said
bore with said first inlet passageway;
a pair of motor control passages communicating with said bore;
a pair of exhaust passages communicating with said bore;
an open-centered first control spool disposed in said bore and
operative to control the flow of fluid between said
passageways;
a second bore disposed parallel to said first bore;
said through passageway communicating with said second bore;
a second inlet passageway communicating with said second bore and
with a second through passage normally communicating with said
exhaust passage;
a combining passageway for providing communication between said
second inlet passage and said first inlet;
a second control spool disposed in said second bore and operative
to direct fluid from said second inlet to combine with fluid from
said first inlet for control by said first spool; and,
said first and second spools are operatively coupled together.
2. The invention of claim 1 wherein said coupling is hydraulic.
3. A control valve, said valve comprising:
a housing having a cylindrical bore formed therein;
a first inlet passageway communicating with the center of said
bore;
an outlet passageway communicating with said bore adjacent the
communication of said inlet passage and communicating along said
bore with said first inlet passageway;
a pair of motor control passages communicating with said bore;
a pair of exhaust passages communicating with said bore;
an open-centered first control spool disposed in said bore and
operative to control the flow of fluid between said
passageways;
a second bore disposed parallel to said first bore;
said through passageway communicating with said second bore;
a second inlet passageway communicating with said second bore and
with a second through passage normally communicating with said
exhaust passage;
a combining passageway for providing communication between said
second inlet passage and said first inlet; and,
a second control spool disposed in said second bore and operative
to direct fluid from said second inlet to combine with fluid from
said first inlet for control by said first spool;
a third control spool co-axially mounted with said mounted spool in
said second bore; and,
said third spool being operative to divert fluid from said through
passage downstream of said first control spool for use by another
control spool.
4. The invention of claim 3 wherein said second spool is operative
with said first spool and said third spool is operative with said
other spool.
5. A hydraulic valve assembly for controlling bi-directional motion
of a plurality of fluid motors, said valve assembly comprising:
a valve body having a plurality of parallel bores;
a plurality of valve elements slidably mounted in said bores;
a pair of said valve elements operatively coupled to move
together;
a first stem mounted for movement in a first bore;
an intake passageway connectable with a first source of pressurized
fluid and communicating with said first bore for admitting
pressurized fluid thereto;
an intake connectable with a second source of pressurized fluid and
communicating with a passageway between said first bore and a
second bore; and,
said pair of valve elements being responsive to combine the fluid
from said inputs and direct it to a selected one of said
outputs.
6. A bank of control valves comprising a housing having a plurality
of parallel bores and a slidable spool in each of said bores;
a plurality of inlet openings;
a common exhaust passage intersecting all of said bores;
a through passage intersecting all of said bores;
a pair of high pressure motor ports intersecting each of said
bores;
a first slidable spool operative to control the flow of fluid from
a first inlet opening;
a second slidable spool operative to control fluid from a second
inlet and from said first inlet; and,
a third slidable spool operative to control fluid from a third
inlet and from said first and second inlets.
7. The invention of claim 6 comprising a fourth spool operatively
connected to operate with said third spool.
8. The system of claim 6 wherein each of said bores are intersected
by a pair of high pressure motor ports and a branched exhaust
passage.
9. The system of claim 8 comprising a pair of anti-cavitations and
relief valves controlling a passageway between each of said high
pressure motor ports and a branch of said exhaust passage.
Description
BACKGROUND OF THE INVENTION
This invention relates to valves, and pertains, more particularly,
to a plurality of cooperating distributor valves.
Backhoes and hydraulic excavators have come into widespread use
because of their versatility. They can, for example, serve the
function of loaders, ditchers, and small cranes.
One drawback of such machines, however, has been their inability to
use the maximum power input to the machine at maximum efficiency.
The hydraulic systems of such systems are known to employ a pair of
pumps for supplying the circuits for operation of a plurality of
motors. The motors normally have separate circuits so that two or
three motors are supplied by one pump and two or three by the
other. This insures that one motor supplied by each pump can be
operated simultaneously. However, if the flow from one pump is not
being used, then it goes to waste. Also, pumps are expensive, and
each pump adds considerable cost to the price of the machine.
Some proposals have been made for combining the fluid from two
pumps for operation of one or more motors, but such proposed
systems have been unsatisfactory. Some such proposals require a
complete diversion of fluid from one system to the other, with the
result that one system is inoperative.
Prior art approaches to combining fluid from two pumps are shown in
U.S. Pat. No. 2,767,550, issued Oct. 23, 1956 to R. Lapsley, and
U.S. Pat. No. 2,322,740, issued June 22, 1943 to H.H. Vanderzee et
al.
Other proposals provide for a parallel connection of all motors
downstream of the track drive motors. This results in a loss of
positive operator control by the stalling of heavily loaded motors
and overrunning of lightly loaded motors.
Still others have proposed a combining of the pumps after the track
drive motors with the remaining motors series connected. This
results in a system where no fluid is available to downstream
motors when the first motor in the series is being operated. That
is, the system can supply only the priority upstream demand.
SUMMARY OF THE INVENTION
Accordingly, it is the primary object of the present invention to
provide a control valve arrangement for a hydraulic system that
overcomes the above disadvantages of the prior art.
Another object of the present invention is to provide a control
valve assembly that is operative to maintain a plurality of fluid
sources separate for separate operation of a plurality of fluid
motors and to automatically combine the flow from the plurality of
sources for actuation of selected motors.
A further object of the present invention is to provide a hydraulic
control valve assembly for combining the output from multiple fluid
pumps in order to supply one or more implements with the combined
output from the multiple pumps.
Another object of the present invention is to provide a valve
system having the operative advantages of a series connected system
and the combining advantages of a parallel system.
A major advantage of the present system is that a plurality of
sources can be used independently or can be selectively combined
for use.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of the present invention
will become more apparent from the following specification when
read in conjunction with the accompanying drawings wherein:
FIG. 1 is a schematic layout of a control system for a hydraulic
excavator incorporating the valve assembly of the present
invention;
FIG. 2 is a schematic illustration in section, of an embodiment of
the present invention;
FIG. 3 is a schematic illustration of a modified form of the
present invention;
FIG. 4 is a sectional view of a valve assembly constructed in
accordance with the present invention;
FIG. 5 is a section taken along lines V--V of FIG. 4;
FIG. 6 is a section taken along lines VI--VI of the valve assembly
of FIG. 4; and,
FIG. 7 is a schematic illustration of a further embodiment of the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings and specifically to FIG. 1, there is
illustrated a circuit for a hydraulic excavator which is
self-propelled and in which all the operations are performed by
hydraulic power. The power for the hydraulic system is supplied by
two main identical variable displacement pumps 10 and 12, a smaller
pump 14 and an auxiliary pump 16, all drawing fluid from a sump or
tank 18, and driven by a suitable engine, not shown. The pump 14
may be fixed or variable displacement to suit the needs of the
system. The main variable displacement pumps 10 and 12 are suitably
connected together by means of a regulator 20 which is responsive
to the needs of the system to regulate the pumps 10 and 12 to
supply optimum pressure and/or flow as required by the system. As
will be explained later, the regulator 20 and the unique valve
assembly arrangement of the present system cooperate to provide a
system having maximum efficiency. Ordinarily the two main pumps 10
and 12 will each supply one half of the working components of the
excavator, however, in the interest of safety, the preferred
embodiment provides for a separate platform swing circuit, as will
be explained later. Furthermore, the valving system provides for
combining of the fluid flow from pumps 10 and 12 for selected
operation of certain components at a higher rate of movement.
The regulator or horsepower limiting means 20 allows the engine
output to be distributed to the pumps according to the requirements
of each pump. Although both pumps 10 and 12 may deliver the same
quantity of oil, the operating pressure of each will vary according
to the function that the excavator is performing. Therefore, the
available engine power can be unevenly distributed to the various
machine elements in accordance with the power needed at the
time.
The pump 10 supplies fluid by way of a conduit 22 to a bank of
distributor valves comprising distributor spools or valve stems 24,
26 and 28 which are operatively connected to distribute fluid
respectively to track drive motor 30, a bucket motor 32, and the
boom motors 34. The pump 12 supplies fluid along the conduit 36 to
a bank of valves comprising distributor valves 40 and 42 and
cross-over valve 44, which are operative to distribute fluid to a
track drive motor 48, and a dipper or stick motor 50.
Pump 14 supplies fluid to a distributor 38 for operation of a slew
motor 46. This fluid, if not used, may either go to exhaust, as
illustrated, or may be available for combining downstream with
fluid from pump 12 for operation of other implements as will be
hereinafter explained. The auxiliary pump 16 supplies fluid for
pilot operation of the main control valves as well as for operating
brakes for the track drive motors and the slew motors.
A schematic layout of a valve assembly is illustrated in FIG. 2
with all the passageways and elements revolved about an axis to the
same plane to facilitate comprehension. The valve assembly
comprises a housing 52 having a plurality of bores 54, 56, 58 and
60, in which are slidably mounted the control spools 38, 40, 42,
and crossover spool 44. The axes of the spools are intersected by a
common plane and the bores are intersected by a through passage 62
and two branches 64 and 66 of a low pressure exhaust passageway. A
plurality of inlet passages comprising a first passage 68 for
supplying fluid to the first spool 38, a second inlet passage 70
for supplying fluid to the spool 40 and a third inlet passage 72
are provided for supplying fluid to the control spools of the valve
assembly. Each of the valve spools are double acting, which means
they are operative to direct fluid to a double acting or reversible
hydraulic motor. The inlets 68 and 70 can be supplied by separate
fluid sources or supplied by a single source using flow dividing
means. The three spools 38, 40, and 42 are also open-centered with
the center intersecting through passage 62 such that fluid not used
by the first valve in the series flows past the center through
passage 62 and is made available for the downstream spool, and so
on, for the series. The through passage comprises a series of
Y-shaped passages 74, 76, 78, and 80 overlapping at the bores and
interconnected thereby.
With the distributor spools in their neutral position, as
illustrated in FIG. 2, for example, fluid entering the valve body
at inlet 68 will flow across spool 38 into passage 74 where fluid
from inlet 70 joins it for continuing flow across spool 40 into
passage 76 and across spool 42 into pasage 78, where it then
continues across spool 44 and exits from the valve body by way of a
drain or return passage 80. With a system as illustrated in FIG. 1,
the fluid will flow by way of a conduit 82 to the inlet of the
valve assembly comprising distributor valves 26 and 28 to be
combined therein with flow from pump 10. Fluid entering the valve
body 52 by way of inlet 72 will, in this illustrated embodiment of
FIG. 1, be fluid which is supplied from pump 10 and has passed
through the open centers of the valve bank in the right hand side
of FIG. 1. This fluid has left that valve bank and flowed along a
conduit 84 to the inlet 72. With the valve system of FIG. 2 in its
neutral position, this fluid entering at inlet 72 will pass along
bore 60 and valve stem 44 into a passageway 86 and then to branch
66 of the exhaust passageway and then out exhaust port 88 to be
returned to the tank or sump.
Looking now to the valve spool 38, we see that if the spool is
moved to the left, such that lands 90 and 92 block the flow of
fluid from inlet 68 into the passageway 74, the fluid pressure will
open check valve 94 permitting the fluid to flow into branch
passage 96. It will then be seen that communication will be
established between the branch supply passage 96 and a high
pressure motor port 98 by means of a groove 100 formed between
lands 92 and 102 on valve spool 38. At the same time, groove 104
formed on spool 38 between lands 106 and 108 will have established
communication between another high pressure motor port 110 and
branch 64 of the exhaust passageway.
Thus, when high pressure fluid is being supplied to one side of a
reversible motor, fluid from the other side of the motor is being
exhausted. Similarly, a movement of the spool 38 to the right, will
reverse the above fluid flow process and consequently the
reversible motor.
Both sides of the motor circuit are protected against excess
pressures by means of a high pressure relief valve 112 provided
between motor port 110 and exhaust branch 64 and a high pressure
relief valve 114 provided between high pressure motor port 98 and
exhaust branch 66. Similarly, each side of the motor is protected
against cavitation by means of an anti-cavitation valve 116 between
motor ports 110 and exhaust passage 64 and an anti-cavitation valve
118 provided in the passageway between motor port 98 and the
exhaust passage 66. These valves operate in the usual manner
independently of the valve spool 38. When excess pressures are
reached in the motor port 110 the valve 112 will open and relieve
pressure into the exhaust passageway 64. Conversely, when pressure
in high pressure motor passage 110 drops below that in the low
pressure exhaust passageway 64, such as when the motor is
over-speeding or over-running, the anti-cavitation valve 116 will
open and permit fluid to pass from the exhaust passageway 64 into
the motor passageway 110 to supplement fluid being supplied thereto
by means of the pump.
The fluid passageway arrangement for spool 40 is similar to that of
spool 38 wherein fluid blocked in the through passage flows past a
check valve 119 to branched supply passage 120 wherein
communication may then be established with a high pressure motor
port 121 or 122 by means of grooves 124 and 126 formed in the spool
40. A pair of high pressure relief valves 128 and 130 are provided
between the high pressure motor ports 121 and 122 and the
respective branches 66 and 64 of the exhaust passageway. A pair of
anti-cavitation valves 132 and 134 are also provided between the
motor ports 121 and 122 and the respective branches 66 and 64 of
the exhaust passageway.
In the illustrated embodiment, the spool 40 controls the flow of
fluid to and from the track motors and for this reason is provided
with a pair of retarding or anti-overspeed valves 136 and 138 which
are operative to retard the flow of exhaust fluid from the motors
to prevent the motors from over-running or running away such as to
cause loss of control of the vehicle. These valves comprise spools
140 and 142 slidably mounted in bores 144 and 146 and biased by
means of springs 148 and 150 to a position to permit communications
by way of passages 152 and 154 and grooves 156 and 158 with the
exhaust passages 66 and 64. Passages 159 and 160 provide
communication between the motor ports 121 and 122 and chambers 161
and 162 at the ends of the spools 140 and 142. If, for example,
motor port 121 is being exhausted to exhaust passageways 66 by way
of passageway 152 and groove 156 the pressure build-up in port 121
resulting from over-running of the motor such as when the vehicle
may be descending a grade, will be communicated by way of passage
159 to the end of spool 140 and chamber 161 forcing the spool 140
to move to the right and restrict the flow of fluid across the
groove 156. When the pressure drops back to a reasonable level, the
spring 148 will force the spool 140 back to the left providing full
open communication between passageway 152 and passageway 66. Thus
it can be seen that the spool 140 operates automatically in
response to over-running of a motor connected with passageway 121,
and thus provides an automatic retarding on the motor itself. The
spool 142 operates in an identical manner to control the flow of
fluid through the motor port 122.
From the foregoing description, it can be seen that the spool 38
can operate a suitable motor from a supply of fluid through inlet
68 while at the same time fluid flowing through inlet 70 may be
diverted by means of spool 40 for operation of a motor connected to
ports 121 and 122 completely independent of the supply fluid
through inlet 68. When the control spool 38 is returned to its
neutral position, the fluid supplied to inlet 68 then flows into
passageway 74 and becomes available together with the fluid through
inlet 70 to be directed by means of spool 40 for control of the
motors connected to passages 121 and 122. Thus, it can be seen that
the first spool 38 is operative to control the flow of fluid from
the first inlet opening 68 while at the same time spool 40 may be
operative to control the flow of fluid from inlet 70 independent of
the inlet 68 and, in addition, is operative to control the combined
flow from the two inlets 68 and 70.
The control spool or distributor 42 has inlet and control passages
arranged similarly to the previous control spools. Movement of
spool 42 in either direction blocks the flow of fluid from passage
76 to passage 78 and directs the fluid past check valve 164 into
branch passage 166 where it may then be directed by means of
grooves 168 and 170 to the motor ports 172 and 174. A pair of high
pressure relief valves 176 and 178 provide communication between
the motor ports 172 and 174 in case of excess pressure therein to
exhaust ports 64 and 66. A pair of anti-cavitation valves 180 and
182 provide communication between the exhaust passageways in the
motor ports in the event of a drop of pressure in the motor line
which is likely to cause cavitation.
A cross-over spool 44 which is operatively coupled to move with the
control spool 42 and facilitate combining of fluid from inlet 72
with that from passageway 76 for distribution by means of spool 42
to a suitable motor connected with motor passages 172 and 174.
Thus, movement of spool 42 causes spool 44 to move in the same
direction, thus blocking flow of fluid from the inlet 72 to
passageway 86 causing it to open check valve 184 and permit flow
into passageway 166 where it combines with fluid from passageway 76
for operation of motors controlled by the stem 42. Thus, it is
apparent that the spool 42 in conjunction with the spool 44 is
operative to combine a flow of fluid from the first inlet 68,
second inlet 70, and a third inlet 72 for operation of a selected
motor. Also, the valve stems 42 and 44 are capable of supplying
fluid from a source 72 for operation of motor at the same time that
valves 40 and 38 are being operated for control of their respective
motors. In other words, the motor operated by valve stem 42 may be
operated from a number of sources of fluid either independently or
combined. Thus, the unique valve arrangement and cooperating
relationship of the valve assembly of the present invention is
capable of providing for extremely versatile operation of a
plurality of hydraulic implements such as a backhoe or hydraulic
excavator.
The embodiment showing FIG. 3 is identical to that of FIG. 2, with
the exception that the stems 42 and 44 of FIG. 2 have been replaced
by stems 188 and 190 with the stem 188 having a completely open
center and the through passage blocking function performed by means
of the central land 192 rather than by land on valve 42 as shown in
FIG. 2. This arrangement has the advantage of distributing the
functions of spools such that the crossover spool 190 performs more
of the function than in the previous embodiment.
FIG. 4 is a sectional view through an actual valve body and
illustrates, among other things, that each of the valve elements or
distributor spools are held in place by compression spring
arrangement. Spool 38, for example, has a compression spring 193,
positioned between washers 194 and 196 which are slidably mounted
on the spool 38 and bear against shoulders thereon for maintaining
the spool in the central position. The washer 196 biases against a
cap member 198 to maintain it in its fixed position with respect to
housing 52. The spool or distributor 40 is similarly provided with
a similar spring 200 for maintaining it in the neutral position. In
addition, provided at each end of the spool 40 are chambers 202 and
204 into which fluid is introduced by means of conduits 206 and 208
for pilot operation of the valve. The spools 188 and 190 are
coupled together by a coupling member 210 for movement together and
are provided with suitable centering means such as springs 212 and
214 arranged as described above. Another feature of interest as
shown in FIG. 4 is that the outlet from spool 38 and the inlet to
spool 40 are actually coupled together in the actual embodiment by
means of an external conduit 216 although the passageway could
conveniently be placed within the valve body itself. This
arrangement permits a complete separation of the circuit controlled
by distributor spool 38, and of distributor spool 40.
An additional feature of the valve assembly, illustrated in FIG. 5,
is a further inlet opening 218 which may be provided for directing
fluid to the spool 188. Thus an additional source of fluid may be
provided such that fluid is always available to the valve 188
despite upstream operation by the other valves.
FIG. 6 illustrates the actual construction arrangement at
cross-over valve 190 and the relationship of the inlet 72 and
outlet 80.
FIG. 7 illustrates an alternate embodiment having two cross-over or
combining spools. One spool provides for combining a new source of
fluid with the supply at the control spool. The other spool
provides for diverting fluid downstream of that spool to provide a
source to be used by another spool.
In particular, there is disclosed in FIG. 7, a valve system
comprising a housing 220 having a plurality of control spools 222,
224, and 226 constructed and arranged substantially as disclosed in
the previous embodiments. The porting and passage arrangement,
however, is such that three different supplies are available
selectively, individually or combined at certain control spools.
For example, an inlet 228 supplies fluid from a first pump or
source solely to control spool 222, where it is either used or
returned via outlet 230 to reservoir.
A second inlet 232 supplies fluid from a second pump or source to
control spool 224. This fluid, if not used, passes along through
passage 234 and becomes available to be used by control spool 226.
The fluid continues past spool 226 if not used there, along passage
236 where it crosses a combining spool 238 and into a return or
exhaust passage 240 for return to reservoir. The spool 238 is
operative upon movement to the right to block the flow of fluid to
exhaust 240 and cause it to flow past a check valve 242 to an
outlet passage 244 to become available to another circuit. Thus, in
the arrangement as illustrated in FIG. 1, the fluid from one bank
of valves would become selectively available to the other bank when
not used in the first.
A third inlet 246 supplies fluid to a combining or cross-over spool
248 disposed in a bore 250. The fluid is permitted to flow along
the spool and out to exhaust passage 240 when the spool 248 is in
neutral. Upon actuation of spool 248, the fluid is forced to flow
along passage 252 through check valve 254 to combine at spool 226
with fluid from passage 234. The valve 248 may be coupled to spool
226 either mechanically or hydraulically to move therewith for
automatic combining when fluid is available. Alternately, the spool
248 may be independently operable for selective combining when
fluid is available at inlet 246.
The selective combining feature is important in situations such as
in operation of a hydraulic excavator wherein at one minute the
operator is carrying out rapid excavation and at the next minute he
may be trimming the excavation at a point adjacent underground
utility lines or the like. In the second instance, it is necessary
that he have full and precise control of the movement of the tool.
Such precise control is best achieved with lower volume of fluid
modulated by the main control spool.
From the above description it is seen that there is disclosed
various control valve arrangements having a plurality of main
control spools, and means operative to combine fluid from a
plurality of sources at selected main control spools.
While the present invention has been described with respect to
specific embodiments, it is apparent that numerous changes and
modifications may be made in the disclosed structure without
departing from the spirit and scope of the present invention as
defined in the appended claims.
* * * * *