Leak-free high-pressure dosing valve with variable flow rate

Abstract

Leak-free dosing valve (30), comprising: A valve housing (32) having a valve bore (48) defining a valve bore axis, the valve bore (48) having a predetermined length between opposite end faces, one of the end faces defining a valve seat (54) at a junction between one of the end faces and the valve bore (48); and a valve element (40) which is movable along the valve bore axis within the valve bore (48), wherein the valve element (40) has a variable metering section (8) between a closing section (5) and an opening section (13), wherein the variable metering section (8) can be inserted into the valve bore (48) with a certain free space between the variable metering section (8) and the valve bore (48) and is movable relative to the valve bore (48) such that the overlap length (50) of the variable metering section (8) overlapping the valve bore (48) varies when the valve element (40) is moved from a closed position to a fully open position, wherein the closing section (5) abuts the valve seat (54) in the closed position, and wherein the opening section (13) allows the variable metering section (8) to be moved out of the valve bore (48) to become,to allow flow over the length of the valve bore (48) between the valve bore (48) and the opening section (13) in the open position; wherein the overlap length (50) between the valve bore (48) and the metering section (8) meters a flow rate through the clearance between a minimum fluid quantity at maximum overlap and a maximum fluid quantity at minimum overlap; wherein the valve element (40) is biased into the closed position by fluid pressure and moved into the open position against the bias of the fluid pressure.

Description

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from U.S. Provisional Patent Application No. 60 / 829777, filed October 17, 2006. STATEMENTS RELATING TO U.S. GOVERNMENT-SPONSORED RESEARCH OR DEVELOPMENT WORK

[0002] Not applicable. FIELD OF THE INVENTION

[0003] This invention relates to hydraulic high pressure valves. BACKGROUND OF THE INVENTION

[0004] The field of hydraulics can be broadly categorized into high-pressure hydraulics, i.e., hydraulics where the pressures involved are above 5,000 psi, and low-pressure hydraulics, where the pressures are less than 5,000 psi. Low-pressure hydraulic applications include applications such as automotive hydraulics, vehicle leveling jacks, and slide-out systems. High-pressure hydraulics, on the other hand, falls into a different class and is generally considered a "strictly industrial" application due to the specialized expertise required to handle these applications.

[0005] In high-pressure hydraulics, forces are generated by high pressures that can exceed 10,000 psi, making force control difficult. In certain applications, such as holding a load with a cylinder, this problem is exacerbated because no or minimal leakage is acceptable. Therefore, valves must not only be operable under high pressure; they must also be leak-free in these applications.

[0006] Some applications also require position or speed adjustment in addition to the on / off action. For these applications, a typical solution is to provide an on / off valve and another valve, such as a needle valve, to perform a metering function. This requires the operation of two valves in unison to enable and adjust the flow rate.

[0007] In addition, some of these applications may require a faster reset function, for example, when the load needs to be quickly returned from a start to a rest position. Therefore, a fast reset function is required in these applications.

[0008] DE 37 05 170 C1 discloses a hydraulic control device.

[0009] US 2 612 342 A discloses a throttle valve for pneumatic tools.

[0010] US 4 350 050 A discloses a liquid flow transducer for detecting a one-way liquid flow.

[0011] DD 56 679 A1 discloses a holding pressure control device for machines processing thermoplastics. SUMMARY OF THE INVENTION

[0012] The present invention provides a valve, particularly for high pressure applications, which can be manually operated by an operator with reasonable force and which can be used to completely shut off or block the high pressure hydraulic flow with almost no leakage, which can be used to simultaneously switch on or release the hydraulic flow and meter the amount of hydraulic flow downstream of the valve, and which can also be actuated to a fully open position for rapid resetting using a single actuator.

[0013] A leak-free metering valve according to the invention comprises a valve housing having a valve bore defining a valve bore axis, the valve bore having a predetermined length between opposing end faces, one of the end faces defining a valve seat at a junction between one of the end faces and the valve bore.A valve element is movable along the valve bore axis within the valve bore, the valve element having a variable metering section between a closing section and an opening section, the variable metering section being able to be provided in the valve bore with a certain clearance between the variable metering section and the valve bore and being movable relative to the valve bore such that the overlap length of the variable metering section overlapping the valve bore varies when the valve element is moved from a closed position to a fully open position. The closing section of the valve element rests against the valve seat in the closed position, and the opening section allows the variable metering section to be moved out of the valve bore in order to control a throughput orTo allow flow across the length of the valve bore between the valve bore and the opening section in the open position. The valve element is biased to the closed position by fluid pressure and moves to the open position against the bias of the fluid pressure.

[0014] According to the invention, the overlap length between the valve bore and the metering section meters a flow rate through the space between a minimum fluid quantity at maximum overlap and a maximum fluid quantity at minimum overlap.

[0015] According to preferred aspects, the valve bore is cylindrical, the closing portion of the valve element is frustoconical, and the three portions are formed integrally with one another. The metering valve can preferably be manually actuated with an actuator, and the actuator is preferably spring-loaded into a closed position of the actuator. The metering valve is further preferably pressure-balanced or compensated to reduce the forces required for actuation.

[0016] The above and other objects and advantages of the invention will become apparent from the following detailed description. Reference is made to the accompanying drawings, which illustrate a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a side plan view of the valve incorporating the invention; Fig. 2 shows a top view of the valve of Fig. 1; Fig. Figure 3 shows a cross-sectional view from the plane of line 3-3 of Fig. 1; Fig. Figure 4 shows a fragmentary cross-sectional view from the plane of line 4-4 of Fig. 2; Fig. Figure 5 shows a fragmentary cross-sectional view from the plane of line 5-5 of Fig. 2; Fig. 6 shows a detailed view of the valve in a dosing position; Fig. 7 shows a similar detailed view as Fig. 6 showing the valve in a closed position; Fig. Figure 8 shows a fragmentary sectional view similar to Fig. 4, but showing the valve in a fully open position; and Fig. Figure 9 shows a schematic representation of the valve in a hydraulic system in which it may be installed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Fig. 1 and Fig. 2 show a valve 30 according to the invention, which has a housing 32 and an actuator 34, which has a tappet 9 ( Fig. 3 - Fig. 5). The plunger 9 is axially slidable within a valve body 36 and is biased upwardly into a closed position of the actuator by a spring 38. The plunger 9 is sealed with respect to the bore of the valve body 36 in which it slides by suitable upper and lower sliding seals 35 and 37, which define a pressure equalization passage 15 between them.

[0018] As in Fig. As shown in Figure 9, a hydraulic system in which a valve 30 according to the invention can be installed comprises a pump 1 or other source of pressurized hydraulic fluid, which supplies pressure through passages 2 and 3 to a spring-returned, single-acting cylinder 10 or other load hydraulic device. The pump outlet line 2 is also connected to the inlet of the valve 30 through the passage 4. The valve 30 has three positions: a leak-free closed position 16, a metering position 17, and a fully open position 18. A valve element 40 has a closing section 5, a metering section 8, and an opening section 13, which determines the function of the valve. The flow from the valve passes through the passage 6 to the passage 7, which communicates with a tank or reservoir 24. In the Fig. 9, there is no flow from the pump 1 to the tank 24, and the full pressure is applied to the load 10 and is maintained by the valve 30. When the valve 30 is in the view of Fig. 9 is shifted to the right into the (middle) metering position 17, a metered amount of fluid is allowed to flow through the valve 30 from the load 10 (and from the pump 1, if switched on) to the tank 24, so that the load 10 can be drawn in either more slowly or more quickly, depending on how much flow must be allowed to pass through the valve 30 before the actuator 34 is actuated. In other words, pushing and positioning the actuator 34 more strongly in a vertical downward direction results in a greater flow than positioning it relatively further upwards into the still open position. As far as applicable, the Fig. 9, the reference numerals used correspond to the reference numerals used to identify physical elements in the other figures.

[0019] When the valve 30 is moved all the way to the right to the fully open position, that is, when the actuator 34 is moved fully downward, a fully open flow or full throughput is enabled through the valve 30 so that the cylinder 10 can retract at the maximum rate by the fluid flowing from the cylinder 10 to the tank 24 through the valve 30.

[0020] In Fig. 9 also shows lines 14 and 15, which are pressure equalization passages, as in Fig. 3. The pressure equalization passages 14 and 15 connect the source pressure and load pressure, respectively, to an upper portion of the bore of the body 36 in which the tappet 9 reciprocates between the seals on the tappet 9. The area at the base of the tappet 9 around which the lower seal 37 extends is larger than the area at the top of the tappet 9 around which the upper seal 35 extends, therefore the pressure exerted in passage 15 creates a purely downward force on the tappet 9, which tends to open the valve. This force is overcome by the hydraulic pressure acting on the bottom of the valve element 40, so that pure pressure acts to close the valve element 40; however, the pressure in passage 15 reduces the magnitude of the force required to open the valve element 40.The magnitude of the force exerted by the pressure in the passage 15 is determined by suitably dimensioning the lower portion of the plunger 9 relative to the upper portion of the plunger 9.

[0021] Fig. 7 shows the closed position 16 of the valve 30; Fig. 6 shows a dosing position 17 of the valve 38 and Fig. 8 shows the fully open position 18. The valve 30 has a valve block 46 which is located in the housing 32 and which is sealed between the high pressure passage 4 and the low pressure passage 6. The valve block 46 has a valve bore 48 therethrough which defines the valve bore axis along which the valve element 40 is movable back and forth. The metering section 8 of the valve element 40 has a close sliding fit with respect to the bore 48, whereby fluid can escape through the space between the section 8 and the valve bore 48, the flow rate of the fluid being variable depending on the overlap length 50 between the section 8 and the bore 48. Larger overlap lengths mean a lower flow rate and shorter overlap lengths mean a higher flow rate.

[0022] At the end of the valve bore 48 adjacent to the closing section 5, in particular at the junction of the valve bore 48 with the axial end face 52, a circular seat 54 is fixed at the corner between the bore and the end face. As shown in Fig. As shown in Figure 7, the seat 54 rests on the closing section 4, which has a frusto-conical shape to create a seal that completely closes off the high-pressure chamber 4 from the low-pressure passage 6. Any enlarged shape (an enlargement relative to the bore 48 and the metering section 8) having a circular cross-section in the plane of the seat 54 in conformity with the shape of the seat 54 is contemplated, for example, a partially spherical shape or a frusto-conical shape to create a shear seal with the seat 54. The seat 54, communicating with the closing section 5, closes off all flow into the bore 48 from the chamber 4.

[0023] The closing section 13, like the dosing section 8, can also be rounded and have the same diameter as the dosing section 8, with the exception that the closing section 13 is flattened on opposite sides, as can be seen from Fig. 7 and Fig. 8 to provide reliefs 60. This provides flow paths between the open section 13 and the bore 48 as the reliefs 60 are moved past the seat 54. This initiates the fully open position when the reliefs 60 have been moved sufficiently past the seat 54.

[0024] Stops 62 formed at the bottom end of the plunger 9 bear against the valve block 46 when the actuator 34 is fully pushed downwards to provide sufficient clearance between the end of the plunger 9 and the bore 48 to allow fluid to exit the bore 48. A spring 64 beneath the valve element 40 opposite the plunger 9 urges the element 40 upwards into a position in which the metering section 8 is adjacent to or intruding into the bore 48 to create a pressure differential that forces the element 40 upwards back into its Fig. 7 shown, fully closed position when the plunger 9 is returned to its upper position.

[0025] In the Fig. 7 and Fig. In the neutral position shown in Figure 9, fluid flow from the pump 1 is directed through the passages 2 and 3 to the workpiece or load and in this case to a single-acting cylinder 10. The flow or flow through the passages 2, 3 and 4 is prevented from returning to the tank 24 by a positive seal between the closing section 5 and the seat 54. This is the leak-free flow blocking position 16, which in Fig. 7 and Fig. 9 is shown.

[0026] In the dosing reset flow or throughput position 17 of Fig. 9, the operator depresses the actuator 34 to move the closure section 5 away from the seat 54 and, by positioning the element 40 in the bore 48, controls the flow from the load 10 back to the reservoir 24. In the metered return flow position, the pump is typically turned off and no flow is allowed to pass through the pump due to outlet check valves, ie, one-way valves in the pump. The backflow or return flow is from the load or cylinder 10 through the passages 3 and 4. When the closing section 5 is moved away from the seat 54 by depressing the plungers 9, a controlled clearance passage is provided between the metering section 8 and the bore 48, which creates a restriction for the flow by means of the controlled clearance between the section 8 and the bore 48, and the overlap distance 50 which is determined by how far the plunger 9 is depressed.This is the flow metering position of . Fig. 6 and position 17 in Fig. 9. As the plunger 9 is further depressed, the amount of backflow or return around the tank is increased due to the reduction in the distance 50 that the fluid must travel between section 8 and bore 48. The force to depress the plunger 9 against the hydraulic pressure acting on the bottom of the element 40 is balanced by the passages 14 and 15, thereby preferentially reducing the force required to actuate the plunger 9 by 85 percent. This reduces the effort required by the user to actuate the actuator 34. This is particularly useful when the valve is used to control pressures in the range of 5,000 - 10,000 psi and higher.

[0027] In the Fig.In the full-flow position shown in Figure 8 and in position 18, undercuts 60 are moved past seat 54, preferably until stops 62 contact the top of valve block 46. In this position, there is virtually no or no restriction to the flow from chamber 4 to passage 6, and significantly less restriction than when metering section 8 is housed in bore 48. This backflow flow or backflow rate results in a rapid retraction speed of single-acting cylinder 10.

[0028] A preferred embodiment of the invention has been explained in detail. Numerous modifications and variations of the described preferred embodiment will be apparent to those skilled in the art. The invention is therefore not to be considered limited to the described embodiment, but is defined by the following claims.

Claims

[1] Leak-free metering valve (30), comprising: A valve housing (32) having a valve bore (48) defining a valve bore axis, the valve bore (48) having a predetermined length between opposite end faces, one of the end faces defining a valve seat (54) at a junction between one of the end faces and the valve bore (48); and a valve element (40) which is movable along the valve bore axis within the valve bore (48), wherein the valve element (40) has a variable metering section (8) between a closing section (5) and an opening section (13), wherein the variable metering section (8) can be inserted into the valve bore (48) with a certain free space between the variable metering section (8) and the valve bore (48) and is movable relative to the valve bore (48) such that the overlap length (50) of the variable metering section (8) overlapping the valve bore (48) varies when the valve element (40) is moved from a closed position to a fully open position, wherein the closing section (5) abuts the valve seat (54) in the closed position, and wherein the opening section (13) allows the variable metering section (8) to be moved out of the valve bore (48) to become,to allow flow over the length of the valve bore (48) between the valve bore (48) and the opening section (13) in the open position; wherein the overlap length (50) between the valve bore (48) and the metering section (8) meters a flow rate through the clearance between a minimum fluid quantity at maximum overlap and a maximum fluid quantity at minimum overlap; wherein the valve element (40) is biased into the closed position by fluid pressure and moved into the open position against the bias of the fluid pressure. [2] Leak-free metering valve (30) according to claim 1, wherein the valve bore (48) is cylindrical. [3] A leak-free metering valve (30) according to any one of the preceding claims, wherein the closing portion (5) is enlarged relative to the metering portion (8) to have a shape in the plane of the valve seat (54) that conforms to the valve seat (54) to provide a shear seal with the valve seat (54). [4] Leakage-free metering valve (30) according to one of the preceding claims, wherein the three sections (5, 8, 13) are integral with each other. [5] Leakage-free metering valve (30) according to one of the preceding claims, wherein the metering valve (30) is manually operable. [6] Leakage-free metering valve (30) according to one of the preceding claims, wherein an actuator (34) of the metering valve (30) is biased into the closed position. [7] Leak-free metering valve (30) according to one of the preceding claims, wherein the metering valve (30) is pressure balanced to reduce the force for opening the metering valve (30). [8] Leak-free metering valve (30) according to one of the preceding claims, further comprising a valve tappet (9) separate from the valve element (40) which is operable by a user to move the metering valve (30) out of the closed position.

Images