Pressure regulator valve

A pressure regulator valve has a valve spool slidably disposed in a valve bore to control the pressure in a hydraulic passage by exhausting excess fluid delivered to the passage. The valve also has a restricted passage which supplies fluid from a main inlet passage to the controlled fluid passage continuously. The restricted passage reduces the amount of valve spool movement required during normal pressure regulation.

BACKGROUND OF THE INVENTION 
The present invention relates to hydraulic control valves and more 
particularly to pressure regulator valves. 
Hydraulic systems generally having a positive displacement for supplying 
pressurized fluid to a plurality of control valves. Pressure regulator 
valves are used to provide controlled pressure levers throughout the 
system by exhausting excess fluid delivered by the pump. The regulator 
valves generally operate by providing a controlled valve connection 
between the main pressure inlet and a controlled pressure outlet and also 
between the controlled pressure outlet and an exhaust passage. 
When a spool type valve is used, the valve overlap; i.e., opening and 
closing of the passages, can result in pulsations of the pressure level at 
the controlled outlet passage. As the system pressure and flow 
requirements increase, the sensitivity of the overlap also increases. With 
the increased flow requirements, system leakage also becomes a factor as 
the amount of overlap increases. 
To provide accurate flow and pressure coverage throughout the desired range 
results in considerable expense in manufacturing the regulator valves to 
the desired accuracy. 
SUMMARY OF THE INVENTION 
The present invention reduces the overlap sensitivity and leakage. The 
valve structure disclosed herein has an orifice or restricted passage 
which provides direct and continuous fluid communication between the 
pressure inlet passage and the controlled pressure outlet passage. The 
valve structure also has a full flow passage connection through which 
fluid flow is controlled by the valve spool. 
The full flow passage connection is closed prior to the exhaust passage 
being opened. The valve overlap therefore only controls flow supplied 
through the orifice passage. Since the potential flow volume through the 
orifice passage is greatly reduced, as compared to the full flow passage, 
the overlap sensitivity is reduced. 
The maximum valve leakage is essentially reduced to the maximum flow volume 
permitted by the orifice passage when the controlled pressure in the 
outlet passage is satisfied and the flow requirement of the system is 
zero. There are very few operating conditions under which zero flow 
requirements will be present, and therefore, the leakage will, in most 
instances, be considerably less than the maximum flow permitted by the 
orifice passage. 
It is an object of this invention to provide an improved pressure regulator 
valve having a valve spool for controlling fluid flow and pressure from an 
inlet passage to an outlet passage, and also wherein, an orifice 
controlled passage provides a continuous flow connection between the inlet 
passage and the outlet passage. 
It is another object of this invention to provide an improved pressure 
regulator valve for controlling fluid pressure in an outlet passage 
wherein a multi-plate valve spool is slidably disposed in a valve bore 
which is connected with an inlet passage, the outlet passage, an exhaust 
passage and a restricted passage, and further wherein the valve spool 
permits continuous fluid flow through the restricted passage from the 
inlet passage to the outlet passage, and also wherein the valve spool has 
control edges on the valve lands thereof for selectively controlling 
direct fluid flow from the inlet passage to the outlet passage and from 
the outlet passage to the exhaust passage.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
Referring to the drawings, wherein like characters represent the same or 
corresponding parts throughout the several views, there is seen in FIG. 1 
a hydraulic circuit having a pump P which draws fluid from a reservoir 10 
and delivers the fluid to a system pressure passage 12. The pressure level 
in the system pressure passage 12, which is distributed to a multitude of 
valve and hydraulic devices, not shown, is controlled by a conventional 
pressure regulator valve 14 which operates in a well known manner. 
The passage 12 is in fluid communication with a main inlet passage 16, 
which in turn is connected with a pressure regulator valve 18. The 
pressure regulator valve 18 includes a valve bore 20, a valve spool 22 and 
a control spring 24. The valve bore 20 is a single diameter bore which is 
closed at both ends. The valve bore 20 is in fluid communication with the 
main inlet passage 16 at a port 25, with a pressure controlled outlet 
passage 26 at ports 28 and 30, with a pair of exhaust ports 32 and 34 and 
with a restricted inlet passage 36 at a port 38. The restricted inlet 
passage 36 is in fluid communication with the main inlet passage 16 
through a restriction or orifice 40. 
The valve spool 22 has a pair of spaced valve lands 42 and 44 which are 
slidably disposed in valve fit within the bore 20. A reduced portion 46 is 
connected between the valve lands 42 and 44 and a spring set position 
member 48 is secured to the valve land 44 and is urged into abutment with 
one end 20A of bore 20 by the spring 24. The spring 24 is compressed 
between the valve land 42 and the other end 20B of valve bore 20. 
The valve land 42 and valve bore 20 cooperate to form a chamber 50 in which 
the spring 24 is disposed. The chamber 50 is continuously connected to 
exhaust through port 34 to prevent pressure buildup within the chamber 50. 
The valve land 44 and the valve bore 20 cooperate to form the pressure 
control chamber 52 which is in fluid communication with ports 28 and 38 
which are connected to passages 26 and 36, respectively. In the spring set 
position shown, the valve spool 22 permits unrestricted fluid flow between 
the main passage 16 and the controlled pressure passage 26. This flow 
occurs from port 25 to port 30 between the valve lands 42 and 44. At the 
same time, continuous fluid flow between the restricted fluid passage 36 
and the pressure controlled passage 26 is present. 
Fluid pressure in the pressure controlled passage 26 operates on the upper 
surface of valve land 44 in the pressure control chamber 52. At a 
predetermined pressure level, the force created on valve spool 22 at valve 
land 44 will be sufficient to overcome the force in spring 24 urging the 
valve spool 22 downward against the spring 24 such that the valve land 44 
will begin closing the port 30 from the port 25. 
As seen in FIG. 3, the unrestricted flow between passage 16 and 26 is 
indicated by the line 54. At a predetermined pressure level, the valve 
spool 22 will be moved sufficiently to close the port 30 completely, such 
that the fluid flow through valve 18 will be reduced, as shown by the line 
56. 
The valve land 44 has a pair of control edges 58 and 60 which are operable 
to control fluid communication between the valve bore 20 and the ports 30 
and 32, respectively. When the control edge 58 closes the port 30, an 
abrupt change in fluid flow through the valve 18 occurs, as represented by 
the curve of FIG. 3. The control edge 60 does not open the port 32 until 
after the port 30 has been closed. In the prior art valves, it is required 
to provide some degree of overlap between the valve closing of the 
pressure inlet and opening of exhaust. These systems result in a flow 
curve represented by dashed line 62 in FIG. 3. 
This overlap flow control does not occur with the pressure regulator valve 
18, since the valve control edge 60 of land 44 does not open exhaust port 
32 until the port 30 has been fully closed. Port 32 will be opened only 
when the flow directed from restricted passage 36 to the controlled 
pressure passage 26 is greater than the flow required by a pressure system 
downstream thereof. The control edge 60 will be effective to open and 
close the exhaust port 32 as required to maintain the downstream pressure 
in passage 26 at a level required by the fluid devices which are connected 
thereto. The flow through port 30 can be directed to lube or sump. 
Should a need for a large volume of fluid occur, the pressure in passage 26 
would be significantly reduced and the valve spool 22 would move to the 
spring set position shown, thereby providing substantially unrestricted 
flow between the passage 16 and the passage 26. 
In FIG. 2, there is seen a valve structure similar to the valve structure 
described above for FIG. 1, wherein a valve bore 20 is in fluid 
communication with the main inlet passage 16, the restricted pressure 
passage 36, the controlled pressure passage 26 and a pair of exhaust 
passages. The valve bore 20 has slidably disposed therein, a valve spool 
100 which has formed thereon a pair of spaced valve lands 142 and 144 
separated by a reduced area or valley 146. 
The valve land 142 and valve bore 20 cooperate to provide the chamber 50, 
which is in fluid communication through exhaust port 34, with an exhaust 
passage. The bore 20 and valve land 144 cooperate to provide a control 
pressure chamber 152 which is in fluid communication through a port 28 
with the passage 26. The passage 26 is also in fluid communication through 
a port 130 with the bore 20. The valve bore 20 is in communication through 
an exhaust port 32 with an exhaust or lube passage, through a port 125 
with the main passage 16 and through a port 138 with a restricted passage 
36. The valve land 144 has a pair of control edges 158 and 160 which are 
operable to control fluid flow between the valve bore 20 and ports 125 and 
32, respectively. 
The valve structure shown in FIG. 2, will operate to provide a flow curve 
identical to that shown in FIG. 3 for the valve 18. However, it should be 
appreciated that the control edge 158 will now be operable to close the 
inlet passage 16 at port 125. This is different from the valve 18, wherein 
the control edge 58 is operable to close port 30 and therefore passage 26 
from the valve bore 20. The resulting fluid flow through the valve is 
unchanged and both embodiments operate in substantially the same manner. 
In FIG. 2, The control edge 160 will not permit communication between 
passage 26 and port 32 prior to the closing of port 125 by the control 
edge 158. 
Those skilled in the art will recognize that the pressure in passage 26 is 
determined by the area of valve lands 44 and 144 which are acted upon by 
fluid pressure in chambers 52 and 152, respectively, and by the force 
stored in the spring 24. It should also be appreciated that by increasing 
the force in spring 24, the pressure in passage 26 will be increased to a 
higher level prior to the closing of ports 30 and 125, and likewise by 
decreasing the end area of valve lands 44 and 144, the pressure in passage 
26 will increase to a higher level prior to valve operation. 
The rate designed into the spring 24 will affect the time or flow volume at 
which the control edges 58 and 158 will close the fluid communication 
between passages 16 and 26. The pressure rise within the passage 26 that 
occurs between the initial movement of valve spool 22, 100 and the opening 
of the exhaust port 32 is represented by line 64 in FIG. 3. The slope of 
line 64 is determined by the rate within the spring 24. 
Obviously, many modifications and variations of the present invention are 
possible in light of the above teaching. It is therefore to be understood, 
that within the scope of the appended claims, the invention may be 
practiced otherwise than as specifically described.