Fluid control valve and plate with filter

Information

  • Patent Grant
  • 6648014
  • Patent Number
    6,648,014
  • Date Filed
    Thursday, February 28, 2002
    22 years ago
  • Date Issued
    Tuesday, November 18, 2003
    21 years ago
Abstract
A hydraulic control valve has a valve block provided with a plurality of ports, a valve body formed with ports corresponding to the ports of the valve block, and a plate disposed between the valve block and the valve body. The plate has a flow passage for providing communication between the ports of the valve block and the ports of the valve body. A filter is disposed in the flow passage.
Description




BACKGROUND OF THE INVENTION




1. Technical Field




The present invention relates to a control valve for controlling a hydraulic pressure. More particularly, the present invention relates to a hydraulic control valve having a filter and also pertains to a plate with a filter for use in a hydraulic control valve.




2. Description of Related Art





FIG. 1

is a sectional view showing a structural example of a conventional hydraulic control valve of the type described above. The hydraulic control valve uses a pressurized working fluid as a control fluid for controlling an actuator such as a cylinder or a motor and also utilizes the pressurized fluid as a drive source for driving a spool. That is, a pressurized fluid led from a fluid supply port


201


in a valve block


200


to a supply port


102


in a valve body


101


of a hydraulic control valve


100


is utilized as a control fluid. At the same time, the pressurized fluid is branched inside the valve body


101


and led to nozzles


106


and


107


of a nozzle flapper mechanism


105


through orifices


103


and


104


. Thus, the pressurized fluid is utilized as a pressure source for driving a spool


108


.




The fluid flowing toward the nozzles


106


and


107


through the orifices


103


and


104


is once filtered through a filter


109


provided in the valve body


101


. The fluid flowing toward the nozzles


106


and


107


passes through narrow gaps, i.e. the orifices


103


and


104


and the nozzles


106


and


107


. Therefore, if the gaps are clogged with particles, the normal function of the hydraulic control valve is impaired. To avoid such a problem, the filter


109


is provided in the valve body


101


.




SUMMARY OF THE INVENTION




Problem to be Solved by the Invention




The hydraulic control valve having a structure in which the filter


109


is incorporated in the valve body


101


as stated above needs to disassemble the hydraulic control valve


100


to replace the filter


109


when it is clogged with particles or maintenance is carried out, and thus requires a troublesome operation. During the replacement, the hydraulic control valve


100


does not function, and the system using it cannot operate. Therefore, the operating rate of the system is reduced undesirably.




To avoid the reduction in the operating rate of the system, it is conceivable that another hydraulic control valve


100


is prepared, and when the filter


109


is to be replaced, the existing hydraulic control valve is changed with the prepared one to operate the system. In this case, however, the system requires another hydraulic control valve


100


. Because there are differences among individual hydraulic control valves, it may be necessary to make readjustment of the system operation and so forth.




There is a hydraulic control valve wherein the filter


109


is detachably provided in the valve body


101


to facilitate the replacement. This arrangement allows the maintenance time to be shortened and is effective in increasing the operating rate of the system. However, because the valve body


101


has a complicated flow passage formed therein, if a filter is further detachably provided in the valve body


101


, the number of machining processes necessary for the valve body


101


increases, resulting in an increase in cost. In addition, when the filter


109


is replaced, care must be taken not to allow particles and the like attached to the filter


109


to enter the inside of the valve body


101


.




The present invention was made in view of the above-described circumstances. An object of the present invention is to eliminate the above-described problems and to provide a hydraulic control valve designed so that filter replacement is facilitated and the filter replacing operation requires a shortened period of time, and also provide a plate with a filter for use in a hydraulic control valve.




Means for Solving the Problem




To solve the above-described problem, according to a first feature of the present invention, there is provided a hydraulic control valve having a valve block provided with a plurality of ports and a valve body formed with ports corresponding to the ports of the valve block, wherein a plate is provided between the valve block and the valve body. The plate is formed with a flow passage for providing communication between the ports of the valve block and the ports of the valve body. In addition, a filter is disposed in the flow passage.




According to a second feature of the present invention, the plate in the above-described hydraulic control valve is formed therein with a flow passage for branching a pressurized fluid from the valve block into a control fluid and a pilot fluid. In addition, the valve body is provided with a pilot port for introducing the pilot fluid from the plate, and the filter is provided in a pilot flow passage in the plate.




According to a third feature of the present invention, the valve body in the above-described hydraulic control valve has a hydrostatic bearing for supporting a spool, and the pressurized fluid from the pilot port is introduced into the hydrostatic bearing.




As stated above, a plate is provided between the valve block and the valve body, and a filter is provided in a flow passage in the plate that provides communication between the ports in the valve block and the ports in the valve body. With this arrangement, filter replacement and maintenance can be performed simply by replacing the plate. Thus, the replacing operation is easy and can be completed in a shortened period of time. Therefore, the period of time during which the hydraulic control valve is unavailable for operation can be reduced to a considerable extent. Accordingly, it is possible to increase the operating rate of a system using the hydraulic control valve.




In comparison to the conventional structure in which a filter is incorporated in the valve body, the flow passage in the valve body is simplified, and the valve body can be made compact in size. In addition, the production cost of the valve body can be reduced.




Further, because the system can be operated simply by preparing two low-cost plates with a filter instead of preparing two costly hydraulic control valves, the overall cost of the system can be reduced.




Further, when it is to be replaced or cleaned, the filter can be detached simply by removing the plate, which is independent of the valve body. Therefore, particles attached to the filter can be prevented from entering the inside of the hydraulic control valve.




Further, it is unnecessary to prepare another hydraulic control valve for the purpose of increasing the operating rate of a system using the hydraulic control valve. The operating rate can be increased simply by preparing a plate of simple arrangement that is equipped with a filter.




Further, it is possible to eliminate the influence on the control performance due to the difference among individual hydraulic control valves that would otherwise occur when the hydraulic control valve is replaced with another hydraulic control valve as in the conventional system.




According to a fourth feature of the present invention, another filter is provided in a control flow passage in the plate in the above-described hydraulic control valve, so that filters of different filtration accuracy are provided in the pilot flow passage and the control flow passage.




If different filters are provided in the control flow passage and the pilot flow passage in the plate as stated above, it is possible to independently filter the control fluid flowing through the control flow passage and the pilot fluid flowing through the pilot flow passage.




With the above-described arrangement, it becomes possible to perform not only filtering of the pilot fluid but also filtering of the control fluid. Therefore, the whole system can be improved in reliability. Further, because the pilot fluid and the control fluid can be filtered independently of each other, it is possible to select filters having filtering performance suitable for the pilot fluid and the control fluid.




According to a fifth feature of the present invention, there is provided a plate detachably installed between a valve block and a valve body in a hydraulic control valve, the valve block being provided with a plurality of ports, and the valve body being formed with ports corresponding to the ports of the valve block. The plate is formed with a flow passage for providing communication between the ports of the valve block and the ports of the valve body, and a filter is disposed in the flow passage.




As stated above, the plate installed between the valve block and the valve body is a plate with a filter, that is, a plate having a filter provided in a flow passage formed therein. Thus, a hydraulic control valve with a filter can be constructed simply by installing the plate between the valve block and the valve body.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a sectional view showing a structural example of a conventional hydraulic control valve.





FIG. 2

is a sectional view showing a structural example of a hydraulic control valve according to the present invention.





FIG. 3

is a sectional view illustrating a cylindrical filter of the hydraulic control valve according to the present invention and a method of installing the filter.





FIG. 4

is a sectional view showing a structural example of the hydraulic control valve according to the present invention.





FIG. 5

is a sectional view showing a structural example of the hydraulic control valve according to the present invention.





FIG. 6

is an enlarged sectional view of a part of the hydraulic control valve according to the present invention in which a disk-shaped filter is secured to a plate.





FIG. 7

is a sectional view showing a structural example of the hydraulic control valve in which a plate without a filter is used.











EXPLANATION OF REFERENCE NUMERALS






10


: valve block,


11


: supply port,


12


: control port,


13


: control port,


20


: plate,


21


,


22


,


23


: flow passage,


24


,


25


: filter,


26


: cap screw,


27


: tapped hole,


28


: plug,


29


: filter,


30


: valve body,


31


: supply port,


32


,


33


: control port,


34


,


35


: pilot port,


36


,


37


: pilot flow passage,


38


: sleeve,


39


: spool,


40


,


41


: hydrostatic bearing,


42


,


43


: bearing orifice,


44


,


45


: orifice,


50


: nozzle flapper mechanism,


51


,


52


: nozzle,


53


: torque motor,


54


: flapper,


60


: displacement sensor,


62


: O-ring.




DETAILED DESCRIPTION OF THE INVENTION




Embodiments of the present invention will be described on the basis of the drawings.

FIG. 2

is a sectional view showing a structural example of a hydraulic control valve according to the present invention. The hydraulic control valve has an arrangement in which a valve body


30


is mounted on a valve block


10


through a plate


20


. A nozzle flapper mechanism


50


is installed on the top of the valve body


30


. A displacement sensor


60


is installed on a side of the valve body


30


.




The plate


20


is formed with flow passages


21


,


22


and


23


allowing a supply port


11


and control ports


12


and


13


of the valve block


10


to communicate, respectively, with a supply port


31


and control ports


32


and


33


of the valve body


30


. Of the three flow passages, the flow passage


21


is branched into three passages. One passage communicates with the supply port


31


of the valve body


30


. The other two passages communicate with pilot ports


34


and


35


leading to the nozzle flapper mechanism


50


. Cylindrical filters


24


and


25


are respectively disposed in the branch passages of the flow passage


21


that communicate with the pilot ports


34


and


35


.





FIG. 3

is a sectional view illustrating the placement of the cylindrical filter


24


and a method of installing the cylindrical filter


24


. Because the cylindrical filter


25


is similar to the cylindrical filter


24


, a description thereof is omitted. The cylindrical filter


24


is secured to the plate


20


with a hollow cap screw


26


engaged with a tapped hole


27


formed in the plate


20


. A pressurized fluid flowing into the flow passage


21


. from the supply port


11


of the valve block


10


is filtered through the cylindrical filter


24


when flowing from the outer periphery to the inside of the filter


24


as shown by the arrows A. Thereafter, the pressurized fluid flows into the pilot port


34


. In other words, the pilot ports


34


and


35


are supplied with the working fluid having particles filtered out through the filters


24


and


25


.




The end of the tapped hole


27


is sealed with a plug


28


. The filter


24


can be detached from the plate


20


by removing the plug


28


and the cap screw


26


. Therefore, replacement and cleaning of the filters


24


and


25


can be readily performed.




When the filters


24


and


25


are to be replaced or cleaned, the plate


20


is replaced with another plate


20


equipped with new filters


24


and


25


, whereby the hydraulic valve can be operated immediately. Alternatively, the plate


20


may be replaced with a plate


20


formed with a branched flow passage but not equipped with a filter as shown in FIG.


7


. In this case also, the hydraulic valve can be operated immediately.




The flow rate of the fluid flowing through pilot flow passages


36


and


37


to nozzles


51


and


52


of the nozzle flapper mechanism


50


is not high, but the fluid flows constantly. Therefore, it is desirable that the filters


24


and


25


have a small mesh size on the order of several microns and a large filtration area. Therefore, a cylindrical filter is selected as each of the filters


24


and


25


. The cylindrical filter has a filtration area over the whole surface of the cylinder and hence provides a large filtration area despite its compact structure. The cylindrical filters


24


and


25


are provided in tunnel-shaped pilot flow passages branching off from the flow passage


21


communicating with the supply port


11


. Thus, the plate


20


can be reduced in thickness by effectively utilizing the tunnel-shaped pilot flow passages.




Next, the operation of the hydraulic control valve arranged as stated above will be described. A spool


39


is slidably disposed in a sleeve


38


with a predetermined clearance. The nozzle flapper mechanism


50


comprises nozzles


51


and


52


, a torque motor


53


, and a flapper


54


. The displacement sensor


60


has an amplifier including a feedback circuit, an amplifier circuit, etc. (not shown) to detect the position of the spool


39


and to perform electric feedback control for the positioning of the spool


39


.




When the spool


39


is displaced, flow passages formed by the above-described components are switched from one to another. Consequently, the supply port


31


communicates with either of the control ports


32


and


33


. At the same time, the other control port and a tank port (not shown) communicate with each other. The opening area of each flow passage is adjusted by the position of the spool


39


, thereby controlling the flow rate of fluid flowing through the flow passage and the pressure applied to the control ports


32


and


33


. An actuator such as a cylinder or a motor is connected between the control port


32


and the control port


33


, and the pressurized fluid is supplied to and discharged from the actuator, thereby controlling the operation of the actuator. It is also possible to control force generated from the actuator by controlling the differential pressure between the two ports.




The pressurized fluid supplied to the pilot ports


34


and


35


flows into spaces at both ends of the spool


39


through orifices


44


and


45


. Further, the pressurized fluid is led to the nozzles


51


and


52


through the pilot flow passages


36


and


37


and blows off from the nozzles


51


and


52


. At this time, the distance between the distal end of each of the nozzles


51


and


52


and the surface of the flapper


54


facing opposite to the nozzle distal end is varied by the torque motor


53


to give resistance to the flow of fluid blowing off from the nozzles


51


and


52


, thereby producing a pressure difference between the upstream sides of the nozzles


51


and


52


, i.e. between the chambers at both ends of the spool


39


. The spool


39


is driven by this differential pressure.





FIG. 4

is a sectional view showing another structural example of the hydraulic control valve according to the present invention. This hydraulic control valve has hydrostatic bearings


40


and


41


at both ends of a spool


39


. In this hydraulic control valve also, a valve body


30


is attached to a valve block


10


through a plate


20


in the same way as in the hydraulic control valve shown in FIG.


2


. Flow passages formed in the plate


20


are also the same as those of the hydraulic control valve shown in FIG.


2


. Flow passages branching off from a flow passage


21


communicating with the supply port


11


communicate with pilot ports


34


and


35


of the valve body


30


through filters


24


and


25


, respectively, in the same way as in the hydraulic control valve shown in FIG.


2


. The hydraulic control valve shown in

FIG. 4

differs from the hydraulic control valve shown in

FIG. 2

in that the pilot ports


34


and


35


communicate with the hydrostatic bearings


40


and


41


through flow passages provided in the valve body


30


.




The pressurized fluid supplied to the hydrostatic bearings


40


and


41


flows through bearing orifices


42


and


43


in the hydrostatic bearings


40


and


41


and through the gap between the spool


39


and the, sleeve


38


. Therefore, if particles are present in the fluid, the bearing orifices


42


and


43


may be clogged with the particles. If particles are caught in the gap between the spool


39


and the sleeve


38


, the spool


39


cannot operate smoothly. Accordingly, the working fluid is filtered through the filters


24


and


25


provided in the plate


20


, thereby preventing the occurrence of problems such as those stated above.




The action and effect obtained by providing the filters


24


and


25


in the plate


20


, which is independent of the valve body


30


, are the same as in the case of the hydraulic control valve shown in FIG.


2


.





FIG. 5

is a sectional view showing another structural example of the hydraulic control valve according to the present invention. This hydraulic control valve has a disk-shaped filter


29


(an enlarged view thereof is shown in

FIG. 6

) in the inlet of the flow passage


21


communicating with the supply port


11


of the plate


20


. Further, filters


24


and


25


are provided in two pilot flow passages of the flow passages branching off from each other at the downstream side of the filter


29


. The disk-shaped filter


29


filters the fluid flowing into both the control flow passage and the pilot flow passage.





FIG. 6

is an enlarged sectional view of a part where the disk-shaped filter


29


is secured to the plate


20


(i.e. an enlarged view of part B in FIG.


5


). The filter


29


comprises a ring-shaped base


29




a


and a metal mesh


29




b


secured to the base


29




a


by caulking. The filter


29


is secured by being fitted into a recess provided at the inlet of the flow passage


21


in the plate


20


. As the filter


29


, a mesh having a small pressure loss is selected according to the control flow rate of the hydraulic control valve. In general, the control flow rate is higher than the pilot flow rate. Therefore, a mesh coarser in mesh (filtration accuracy) than the downstream filters


24


and


25


, e.g. a mesh size on the order of several 100 microns, should be selected. Reference numeral


62


denotes an O-ring interposed between the valve block


10


and the plate


20


.




As stated above, the disk-shaped filter


29


of coarse mesh is provided upstream from a point where the fluid from the supply port


11


is branched into the control fluid and the pilot fluid. Consequently, even if relatively large particles are mixed in the fluid, these particles can be removed. If particles that are so large as to get caught in the filter


29


are attached to the pilot-side filters


24


and


25


, the pilot-side filtration area is reduced, and the flow resistance increases. This may cause the valve function to be impaired. Therefore, the disk-shaped filter


29


provided in the pre-stage performs the function of preventing large particles from flowing into the control flow passage and the function of allowing the downstream filters in the pilot flow passages to stand prolonged use.




It should be noted that the hydraulic control valve shown in

FIG. 5

has filters provided in both the control and pilot flow passages. In this regard, a disk-shaped filter may be provided in the inlet of the flow passage


21


communicating with the supply port


11


formed in the plate


20


of the hydraulic control valve having the hydrostatic bearings


40


and


41


as shown in FIG.


4


.




EFFECT OF THE INVENTION




As has been described above, the invention set forth in each claim provides advantageous effects as follows.




As stated above, a plate is provided between the valve block and the valve body, and a filter is provided in a flow passage in the plate that provides communication between the ports in the valve block and the ports in the valve body. With this arrangement, filter replacement and maintenance can be performed simply by replacing the plate. Thus, the replacing operation is easy and can be completed in a shortened period of time. Therefore, the period of time during which the hydraulic control valve is unavailable for operation can be reduced to a considerable extent. Accordingly, it is possible to increase the operating rate of a system using the hydraulic control valve.




In comparison to the conventional structure in which a filter is incorporated in the valve body, the flow passage in the valve body is simplified, and the valve body can be made compact in size. In addition, the production cost of the valve body can be reduced.




Further, when it is to be replaced or cleaned, the filter can be detached simply by removing the plate, which is independent of the valve body. Therefore, particles attached to the filter can be prevented from entering the inside of the hydraulic control valve.




Further, it is unnecessary to prepare another hydraulic control valve for the purpose of increasing the operating rate of a system using the hydraulic control valve. The operating rate can be increased simply by preparing a plate of simple arrangement that is equipped with a filter. In addition, the overall cost of the system can be reduced.




Further, it is possible to eliminate the influence on the control performance due to the difference among individual hydraulic control valves that would otherwise occur when the hydraulic control valve is replaced with another hydraulic control valve as in the conventional system.




According to the fourth feature of the present invention, different filters are respectively provided in the control flow passage and the pilot flow passage in the plate. Thus, it is possible to independently filter the control fluid flowing through the control flow passage and the pilot fluid flowing through the pilot flow passage, in addition to the above-described effects.




According to the fifth feature of the present invention, the plate installed between the valve block and the valve body is a plate with a filter, that is, a plate having a filter provided in a flow passage formed therein, and this plate is installed between the valve block and the valve body. Accordingly, it is possible to construct a hydraulic control valve having the above-described advantageous effects.



Claims
  • 1. A hydraulic control valve having a valve block provided with a plurality of ports and a valve body formed with ports corresponding to the ports of the valve block, wherein a plate is provided between the valve block and the valve body, said plate being formed with a flow passage for providing communication between the ports of the valve block and the ports of the valve body, and wherein a branched flow passage is formed in said plate to branch a pressurized fluid from said valve block passing through said flow passage into a control fluid and a pilot fluid, said valve body being provided with a pilot port for introducing the pilot fluid passing through said branched flow passage, and a filter is provided in said branched flow passage.
  • 2. A hydraulic control valve according to claim 1, wherein said filter is secured to the plate with a hollow cap screw engaged with a tapped hole formed in said plate, and an end of said tapped hole is sealed with a plug, so that said filter can be detached from the plate by removing said plug and said cap screw.
  • 3. A hydraulic control valve according to claim 1, wherein said valve body has a hydrostatic bearing for supporting a spool, and the pressurized fluid from said pilot port is introduced into said hydrostatic bearing.
  • 4. A hydraulic control valve according to claim 1, wherein another filter is provided in a flow passage in said plate, said another filter having a filtration accuracy different from that of the filter provided in said branched flow passage.
  • 5. A plate detachably installed between a valve block provided with a plurality of ports and a valve body formed with ports corresponding to the ports of said valve block, said plate comprising:a flow passage for providing communication between the ports of said valve block and the ports of said valve body; a branched flow, passage for branching a pressurized fluid from said valve block passing through said flow passage into a control fluid and a pilot fluid; a pilot port provided in said valve body to introduce the pilot fluid passing through said branched flow passage; and a filter disposed in said branched flow passage.
Priority Claims (1)
Number Date Country Kind
11-247972 Sep 1999 JP
PCT Information
Filing Document Filing Date Country Kind
PCT/JP00/05820 WO 00
Publishing Document Publishing Date Country Kind
WO01/16514 3/8/2001 WO A
US Referenced Citations (7)
Number Name Date Kind
2961002 Gordon Nov 1960 A
3006371 Giles Oct 1961 A
4186909 Patel Feb 1980 A
4267862 Neff et al. May 1981 A
4333498 Huling Jun 1982 A
5697401 Shinoda et al. Dec 1997 A
5722456 Schumacher et al. Mar 1998 A
Foreign Referenced Citations (2)
Number Date Country
2-102982 Apr 1990 JP
8-270820 Oct 1996 JP
Non-Patent Literature Citations (2)
Entry
Microfilm of the specification and drawings annexed to the request of Japanese Utility Model Application No. 9603/1989 (Laid-open No. 101185/1990) (Mitsubishi Heavy Industries, Ltd.), Aug. 13, 1990.
Microfilm of the specification and drawings annexed to the request of Japanese Utility Model Application No. 56826/1989 (Laid-open No. 146262/1990) (Kabushiki Kaisha Ookane Seisakusho), Dec. 12, 1990.