Valve with operation parameter set at assembly and pump using same

A valve is assembled by telescoping a first body component relative to a second body component until reaching a relative position that corresponds to a predetermined valve operation parameter, such as a valve opening pressure. The first body component is then fixed with respect to the second body component at the relative position, such as by laser welding. The present invention finds potential application as a cartridge valve for a pump, such as a pressure relief valve and/or pressure reduction valve. The relative positioning control over the body components de-sensitizes valve operation from variations in valve components, such as variations attributable to geometrical tolerances.

TECHNICAL FIELD

The present invention relates generally to valves, and more particularly to valves with a preset operation parameter.

BACKGROUND

In one class of valves, the valve member is intended to move to a particular position when acted upon by a predetermined force. For instance, in the case of a pressure relief valve, the valve member would be biased toward a closed position, but could open when fluid pressure acting on an opening hydraulic surface exceeds some predetermined valve opening pressure. In another example, a pressure reducing valve moves to an open position when pressure on the low pressure side of the valve drops below some predetermined valve opening pressure. Because these valves must often be comprised of several components, and each of those components must have a realistic manufacturing tolerance, mass producing valves with consistent valve opening pressures can be problematic. Some of these problems can be attributed to difficulty in setting a desired valve operation parameter, such as valve opening pressure, when stacked geometrical or other tolerances result in a plurality of valves all with slightly differently shaped or strengthened components. Variations on the desired valve operation parameter can often be a strong function of variability among component tolerances, and the problem is often compounded by stacked tolerances from multiple components.

The present invention is directed to these and other problems associated with mass producing valves with consistent and/or predictable valve operating parameters.

SUMMARY OF THE INVENTION

In one aspect, a valve assembly includes a first body component fixed with respect to a second body component in a selected relative position, which corresponds to a predetermined valve operation parameter, such as a valve opening pressure.

In another aspect, a method of assembling a valve includes a step of adjusting a relative positioning of a first body component relative to a second body component until reaching a relative position that corresponds to a predetermined valve operation parameter. The first body component and the second body component are then fixed in the relative position.

In still another aspect, a pump includes at least one cartridge valve assembly threadably attached to a pump body. Each of the cartridge valves has a first body component fixed with respect to a second body component in a selected relative position that corresponds to a predetermined valve operation parameter.

DETAILED DESCRIPTION

Referring now toFIG. 1, a pump system10includes an electronically controlled pump11, which is controlled in a conventional manner by an electronic control module12. For instance, pump11could be a known fixed displacement, variably output axial piston pump of a type generally described in co-owned U.S. Pat. No. 6,035,828 to Anderson et al. For example, that pump might include a plurality of pistons driven to reciprocate by a rotating angled swash plate. An output controller would control whether the fluid displaced by the pump pistons is pushed into a high pressure outlet or merely returned to a low pressure side for recirculation. The output controller could be of any suitable structure and be controlled by an electronic control module12in a conventional manner.

Pump11includes a low pressure inlet connected to a low pressure inlet gallery20, and a high pressure outlet16connected to a high pressure outlet gallery30. Low pressure inlet gallery20and high pressure gallery30are potentially connectable via pumping portion24, a controller leak passage29or a pressure relief passage31. In one aspect of the invention, pump body15includes a cartridge cavity33holding a pressure relief valve to normally close pressure relief passage31. In another aspect, a pressure reduction valve40is positioned in a cartridge cavity47so that pump output controller18is provided with a relatively medium pressure, which is stepped down from the high pressure output gallery30. When in operation, a rotating shaft17causes a pump portion24to draw fluid from low pressure inlet gallery20via internal supply passage22, and deliver the same to a fluid diverting means19. Depending upon the state of fluid diverting means19, a usually large portion of the fluid is pushed into high pressure outlet gallery30via high pressure passage26, and a typically lessor portion is diverted into low pressure passage25for recirculation to low pressure inlet gallery20. Fluid diverting means19is a portion of pump output controller18, which also includes an electro hydraulic actuator27in communication with electronic control module12via a communication line28.

The output rate of pump11is generally determined by the rotation rate of shaft17and the ratio of fluid delivered to respective high pressure passage26and low pressure return passage25by fluid diverting means19, as determined by electro hydraulic actuator27. For example, fluid diverting means19could represent a set of sleeves mounted around pump pistons. The sleeves can be moved by an electro hydraulic actuator27between positions that port different fractions of the pumping piston's stroke fluid back to the low pressure inlet gallery20. The sleeves can also be positioned such that virtually all of the fluid displaced by the pump pistons is pushed into high pressure passage26. In one example, the electro hydraulic actuator27consumes some relatively small amount of high pressure fluid from outlet gallery30to perform its function of adjusting the state of fluid diverting means19. However, the amount of fluid used for this purpose is reduced, and the pressure at which the output controller18operates is made relatively uniform by the inclusion of pressure reduction valve40. The pressure reduction valve40is intended to provide electro hydraulic actuator27with a steady supply of uniform pressure fluid via a reduction valve inlet43and a reduction valve outlet41. The state of pressure reduction valve40is preferably determined via a reduction valve pressure tap42, which communicates the operating pressure of the electro hydraulic actuator27to pressure reduction valve40. When pressure in electro hydraulic actuator27drops below a pre-determined threshold, pressure reduction valve43opens inlet43larger to outlet41to raise pressure in actuator27. When pressure exceeds a predetermined maximum pressure, pressure reduction valve43can move toward a closed position. When pressure in outlet gallery30exceeds a predetermined maximum, pressure relief valve32relieves pressure to inlet gallery20via pressure relief passage31. In particular, when pressure in the upstream portion of relief passage31exceeds a predetermined pressure, relief valve inlet36is opened to relief valve outlet34to vent excess pressure.

Referring now toFIG. 2, pressure relief valve32is preferably a cartridge type valve that includes a plug body component50attached to a seat body component51to contain a valve member52and a biasing spring53. A pneumatic, hydraulic, magnetic, or other spring type could be substituted as a biaser in place of spring53. Biaser53normally biases valve member52toward a position that places valve surface65in contact with valve seat69to normally close relief valve inlet36to relief valve outlet34. A washer55separates valve member52from biasing spring53, which is positioned in a spring cavity56with a stop62. When fluid pressure acting on an opening hydraulic surface66exceeds a predetermined valve opening pressure. Valve surface65separates from valve seat69to open fluid passage67. Stop62defines the maximum travel of valve member52, which includes a spring cavity vent passage61, that vents spring cavity56to the low pressure at relief valve outlet34. When installed in pump body15, o-ring seals60and64as well as ring back up63isolate relief valve inlet36from relief valve outlet34. The cartridge cavity33of pump body15includes internal threads that match external threads57on plug body component50, allowing simple installation via appropriate torqueing via hex tool opening58about centerline59. The valve opening pressure of pressure relief valve32can be finally tuned by adjusting the relative position of plug body component50relative to seat body component51before attaching the two via an annular weld at weld location68. In other words, the pre-load from biaser53can be adjusted by telescoping plug body component50with respect to seat body component51until the force produces a predetermined valve opening pressure; the two components are then laser welded at weld location68.

Referring now toFIG. 3, pressure reduction valve40shares many features in common with pressure relief valve32, but performs a much different function. Like pressure relief valve32, pressure reduction valve40includes a plug body component71that telescopically receives a seat body component72, within which are trapped a valve member73and a biaser, such as biasing spring74. A washer81separates biaser74from valve member73, which includes a control hydraulic surface85oriented in opposition to the force from spring74. Biasing spring74is positioned in a spring chamber76that is vented to a low pressure space between o-ring seal79and external threads92via a spring chamber vent passage80. Depending upon the fluid pressure in pressure control chamber88acting on control hydraulic surface85, and the force from biasing spring74, reduction valve inlet43can be opened to reduction of outlet41past edge seat84. Thus, in this example embodiment, valve member73acts as a spool valve member instead of as a poppet type valve member as in the embodiment ofFIG. 2. Pressure control chamber88is dampened from the effects of pressure fluctuations upstream of reduction valve pressure tap42by the inclusion of a restricted passage87defined in a plug86attached to seat body component72. When installed in pump body15, a seal surface75and o-ring seal90and ring back up89isolate the higher pressure existing at reduction valve inlet43from the medium pressure existing at reduction valve outlet41and pressure control chamber88. Like the pressure relief valve32, pressure reduction valve40is installed via a hex tool opening77with an appropriate torque about centerline78to seat seal surface75in an appropriate seat defined by the pump body in its cartridge cavity. When pressure in the pressure control chamber88drops below a predetermined value, valve member73moves to a position to open edge seat84so that inlet43is open to outlet41via fluid passage82, which includes annulus83. When pressure is higher in pressure control chamber88, valve member73is pushed back toward a position to close edge seat84. Like the pressure relief valve32, the valve opening pressure for pressure reduction valve40can be established by adjusting the relative position of plug body component71to seat body component72before they are attached at weld location91. In addition, the present invention contemplates another valve operation parameter, namely the flow area through pressure reduction valve40when valve member73is in its open position, since the valve member73of pressure reduction valve40does not move between fixed stops.

INDUSTRIAL APPLICABILITY

Although the present invention has been illustrated in the context of cartridge valves for a variable delivery pump, the present invention could find potential application in non-cartridge valve situations and/or in fluid handling apparatuses other than pumps. Nevertheless, the present invention finds particular application as a replaceable component in a fixed displacement variable delivery pump for use in supplying fluid to, and controlling pressure in, a common rail fuel injection system for an engine. For instance, those skilled in the art will appreciate that both the pressure relief valve32and the pressure reduction valve40could find potential application in a wide variety of different fluid systems, that may or may not benefit from a cartridge structure as shown in the illustrated embodiments. In other words, the valves of the present invention need not necessarily be cartridge valves, and could find potential application in fluid handling devices other than pumps.

Referring now toFIGS. 4–9, the assembly procedure for a pressure reduction valve is illustrated to show how a valve according to the present invention can be assembled to produce a predetermined valve operation parameter, such as valve opening pressure, even in the light of geometrical variations in different parts as well as variations in spring strength. An assembly jig100includes an upper portion101that can be moved or fixed vertically with respect to a lower portion102. When assembly jig100is in operation, a probe104can apply a force to control hydraulic surface85, in a manner simulating fluid pressure if the valve were installed in pump11. The force on valve member73can be measured by force indicator105in a known manner. Probe104and force indicator105are parts of upper portion101, and maybe fixed in position on the upper portion by a probe clamp106. The upper portion101also includes a seat component clamp107that may be maneuvered into a position to clamp seat body component72relative to upper portion101. Likewise, lower portion102includes a plug component clamp120for clamping onto plug body component71of pressure reduction valve40. Assembly jig100also includes a source of pressurized fluid13, such as pressurized air, connected to reduction valve inlet41via an inlet passage112. Reduction valve inlet43is connected to a low pressure source via outlet passage111, which includes a flow meter110that can measure the flow rate of fluid through outlet passage111, and hence through pressure reduction valve40. Those skilled in the art will appreciate that source113preferably produces a predetermined pressure gradient across pressure reduction valve40so that a predetermined flow rate of a known gas at a predetermined pressure gradient can be calibrated to indicate a predetermined flow area through pressure reduction valve40. This predetermined flow area would be indicative of the flow area through the valve when in its open position. Those skilled in the art will also appreciate that the pressure gradient through or across pressure reduction valve40when in assembly jig100is in the reverse to that normally experienced when the valve is installed in the pumpFIG. 1.

Assembly proceeds by placing the components that make up pressure reduction valve40in the gravity held manner shown inFIG. 4within assembly jig100. Next, as shown inFIG. 5, plug component71is clamped to plug component clamp120of lower portion102, while upper portion101clamps to seat body component72via seat component clamp107. In addition, probe104is moved into a position adjacent to valve member73. In the next step, shown inFIG. 6, the flow area through the valve is adjusted by adjusting the position of valve member73relative to seat body component72with probe104until edge seat84is closed. This closed point is generally indicated when the pressurized fluid leakage past edge seat84is below some predetermined level. At this point, flow meter110is recalibrated to zero. Next, the force produced by probe104is reduced so that valve member73moves toward a position opening flow past edge seat84. When flow meter110indicates some predetermined flow rate, the operator should know that it is indicative of a predetermined flow area past edge seat84. In the illustrated embodiment, this predetermined flow area is preferably similar to the maximum flow area through the pump output controller18, so that the pressure reduction valve operation corresponds closely to the flow area fluctuations through the electro hydraulic actuator27of the pump controller18. Thus, when a predetermined flow area through the valve is achieved, probe clamp106is activated to fix the position of valve member73with respect to seat body component72as shown inFIG. 7. In the step shown inFIG. 8, the upper portion101is moved vertically with respect to the lower portion102until force indicator105indicates a predetermined load on valve member73when it is in its open position as defined by the steps ofFIGS. 6 and 7. This movement causes seat body component72to telescope within plug body component71. Thus, when the desired opening area and opening pressure force are achieved as shown inFIGS. 6,7and8, the two body components are laser welded at weld location91, such as by rotating assembly jig100, while appropriately positioning laser welder130. Those skilled in the art will appreciate that the now assembled pressure reduction valve40will be biased toward a closed position but will open when a fluid pressure force in a control hydraulic surface85of valve member73drops below a predetermined level.

The pressure relief valve32is assembled much in a similar manner to that of pressure reduction valve40, except that no fluid flow rate measurements need be done. In other words, the unattached valve is positioned in the assembly jig100. The respective seat and body component clamps are then clamped onto the respective seat and body components of the valve. Next, the probe is moved in position into contact with the valve member. Nevertheless, the fluid flow apparatus can still be used as a method of determining when the valve opened in the case of assembling the pressure relief valve32. The respective body and seat components are telescoped with respect to one another until the probe indicates that the force indicator105of probe104indicates the desired valve opening pressure. The two body components are then laser welded in a manner similar to that described with respect to the pressure reduction valve40assembly.

Those skilled in the art will appreciate that the structure and assembly strategy of the present invention allows tolerances for valve components to be relaxed while at the same time having the ability to tighten the tolerances on an important valve feature, such as a valve operation parameter. In the illustrated embodiments, this valve operating parameter has been illustrated as a valve opening pressure for a pressure reduction valve along with a predetermined valve flow area when such a valve is in its open position, as well as a predetermined valve opening pressure for a pressure relief valve. Thus, the present invention allows for the possible elimination of category parts, such as spacers in order to trim a valve produced to some desired valve opening pressure. By making the valve in a cartridge form and laser welding it, a tamper resistant package is produced that is an easily serviceable aspect of the pump illustrated inFIG. 1. Thus, the present invention provides a structure and methodology capable of reducing costs while simultaneously improving quality, reliability, and predictability.

It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present invention in any way. For instance, while the invention has been illustrated in the context of hydraulic valves, the present invention is also applicable to pneumatic systems. In addition, while the invention has been illustrated in the context of a valve opening pressure, the invention is also applicable to setting a valve member movement force. That force could be supplied by fluid pressure or an electrical actuator. In addition, valve movement may be a closing force in another application, rather than valve opening forces as in the illustrated embodiments. Thus, those skilled in the art will appreciate that other aspects, objects, and advantages of the invention can be obtained from a study of the drawings, the disclosure and the appended claims.