EP0234006A2 - Hochdruckpumpe mit veränderlicher Fördermenge - Google Patents
Hochdruckpumpe mit veränderlicher Fördermenge Download PDFInfo
- Publication number
- EP0234006A2 EP0234006A2 EP86116392A EP86116392A EP0234006A2 EP 0234006 A2 EP0234006 A2 EP 0234006A2 EP 86116392 A EP86116392 A EP 86116392A EP 86116392 A EP86116392 A EP 86116392A EP 0234006 A2 EP0234006 A2 EP 0234006A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- piston
- swash plate
- cylinder
- pump
- drive shaft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/14—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having stationary cylinders
Definitions
- This invention relates to variable displacement piston pumps and particularly to pumps of the type described which are compensated to maintain constant pressure with variable flow. More particularly, this invention relates to means for force balancing of the piston thrust loads to provide a relatively lightweight, high pressure pump.
- a type of variable displacement piston pump known in the prior art includes a shaft having a driven end and an opposite end arranged for supporting a swash plate.
- the swash plate is caused to pivot about an axis displaced from and generally perpendicular to the center line of the driven shaft.
- a plurality of cylinders having pistons disposed therein are arranged with associated check valves in a fixed pump block.
- pressure in the cylinders becomes high enough to open the check valves and deliver fluid to a common discharge manifold.
- the manifold pressure approaches a predetermined set value, a force is created which is transmitted to the swash plate and pivots the swash plate away from a maximum flow position.
- the pistons are arranged with respect to the swash plate so that when the swash plate pivots away from the maximum flow position, the stroke of the pistons is decreased to reduce fluid flow and pressure. Equilibrium is thus established and a reduced fluid flow at a predetermined substantially constant pressure is maintained.
- U.S. Patent 4,149,830 having Frank Woodruff as the named inventor.
- a plurality of piston assemblies are permitted to reciprocate in a cylinder block which is fixed to the pump casing.
- the swash plate in addition to pivoting to achieve equilibrium is caused to rotate.
- the rotation of the swash plate forces the pistons to reciprocate, thus achieving the desired pump action.
- the drive shaft and the attached swash plate form a rotating assembly. This rotating assembly must supply sufficient axial force against the piston assemblies to cause pumping.
- variable displacement high pressure piston pump the forces involved in actuating the pumping pistons are balanced by using dummy pistons to create a force equal and opposite to the force developed by the working pistons.
- the dummy pistons work against a non-tilting plate attached integrally to a shaft which supports the tiltable swash plate. The majority of the axial thrust forces are thus contained within rotating elements and not transmitted to the pump housing.
- the non-tiltable thrust plate is formed into a centrifugal pump impeller, integral with the drive shaft, to boost inlet fluid pressure. Boosting inlet fluid pressure prevents cavitation in supplying fluid to the pumping piston assemblies.
- the dummy piston and the working piston in each cylinder have openings formed there through so that hydraulic fluid flows from both ends into the pump cylinder chamber.
- the tilt swash plate tilts in response to a control fluid pressure.
- the control fluid is supplied through an intermediate transfer tube within a hollow drive shaft to decrease the control fluid volume and speed response.
- the drive shaft assembly employs arcuate cutouts which both cradle and drive the tiltable swash plate. Moving the tiltable swash plate in the cradle is facilitated by using a permanently lubricated bearing material.
- Pump 10 is capable of working at high pressures, 8000 psi and above, and is relatively lightweight and suitable for aircraft hydraulic systems. Hydraulic fluid is fed at low pressure to pump 10 through an inlet port 12 and is discharged at the desired pressure from an outlet port 14.
- Pump 10 includes a rotating assembly 16 which rotates within a housing 18. Housing 18 includes a mounting flange 20 by which pump 10 is mounted to a suitable power source such as a gear casing of a gas turbine engine (not shown).
- the rotating assembly 16 includes a splined input shaft having spline teeth or other suitable means for engaging a power take off output of the power source.
- a fixed steel cylinder block 22 having a plurality of cylinder bores 24 formed therein is disposed between aluminum end members 15 and 17 to form part of a housing 18. While cylinder block 22 includes a plurality of cylinder bores 24 only one is shown in the section view of Figure 1 and operation of only one will be described. Cylinder block 22 is fixed between members 15, 17 and its outer surface is exposed as part of a housing or shell 18. Each cylinder 24 in block 22 houses an active pumping piston 26 and a dummy piston 28. Active pistons 26 receive their motion from rotation of the inclined swash plate 30. The outer end of active piston 26 engages a shoe 32 and the outer end of dummy piston 28 engages a shoe 34. A spring 36 is disposed in cylinder 24 to bias apart pistons 26 and 28.
- Rotatable drive assembly 16 includes a center shaft 40 extending to form integral thrust plate 38.
- the axial forces, generated during pumping, on swash plate 30 also react on shaft 40 and the axial forces are contained within the rotating drive assembly 16 and not transmitted to housing 18.
- active piston 26 moves with respect to cylinder 24 as swash plate 30 rotates to effect pumping action.
- the dummy piston 28 remains substantially in the same position with respect to cylinder 24 while pumping; although, it is free to float in order to adjust for discrepancies in the relative distances between parts of the rotating assembly 16 and in order to transfer axial forces from the pumping action of the active piston 26 outside of cylinder 24 to the thrust plate 38.
- Swash plate 30 is mounted around center shaft 40.
- Swash plate 30 is pivotally mounted to the rotating shaft assembly 16.
- Circular projections 31 on swash plate 30 fit into arcuate openings 43 formed on cradle 44.
- the operation of swash plate 30 is conventional and is described in detail in U. S. Patent 4,149,830. Briefly, swash plate 30 pivots relative to cradle 44 around an axis 42.
- the drive shaft assembly 16 thus employs arcuate cutouts 43 which both cradle and drive the swash plate 30. Easy movement of swash plate 30 in cradle 44 is made possible by utilizing a permanently lubricated bearing material on the mating surface or by hydrostatic bearings.
- Swash plate 30 is not pinned to cradle 44. Force vectors are such as to ensure swash plate 30 is securely seated in the arcuate bearing pockets 43 under all conditions.
- Swash plate 30 pivots about center 42 in the arcuate pockets 43 which rotate with shaft 44.
- Swash plate 30 pivots in the arcuate cutouts 43 and cradle 44 in response to outlet pressure.
- Swash plate 30 may be positioned at varying angles to the center axis 46 of pump 10.
- Swash plate 30 is rotationally fixed to center shaft 40 and therefore, whenever its working face 48 is displaced from the perpendicular with respect to axis 46, active pistons 26 are reciprocated as drive assembly 16 rotates.
- swash plate 30 is pivoted to bring the working surface 48 towards perpendicular alignment with axis 46.
- swash plate 30 is tilted at a greater angle with respect to perpendicular alignment with axis 46. Tilting of swash plate 30 is accomplished through pressurized fluid, at the outlet pressure, within passage 63.
- Shoes 32 are hydraulically balanced at both the piston 26 and swash plate 30 interface.
- shoes 34 are hydraulically balanced at both piston 28 and thrust impeller plate 38.
- the shoes 32, 34 are similar to shoes described in U.S. Patent 4,149,830. Pressure balancing of shoes 34, 32 is accomplished by the through hole and the vented annulus cut in the end of the shoe away from its associated piston 26, 28. The through hole pressure plus pressure distribution across the ends balance any forces developed by the pistons. The vented annulus helps to provide a constant fluid film and prevent overpressurization.
- Each cylinder pump has associated therewith a check valve assembly 50, one of which is shown in Figure 1.
- Minimizing discharge pulsations in a high pressure pumping unit is an important criteria towards accurate system performance.
- An effective way of achieving a smooth pulse trace is through the use of individual check valves 50 with each pumping cylinder 24.
- fluid from each check valve piston assembly will be expelled just after system pressure plus valve spring force return is met. There is no possibility of exposing the system to a lesser discharge pressure than desired; therefore, the possibility of increased pulsation is reduced.
- the discharge from pumping cylinders 24 during operation is through the associated check valve 50 into a common manifold 52.
- a compensating valve 54 which communicates with manifold 52 is utilized.
- Compensating valve 54 is described in detail in U.S. Patent 4,182,365.
- Compensating value 54 modulates discharge pressure.
- Pressurized fluid for controlling the inclination of swash plate 30 is provided by compensating valve 54 through passage 56 and a balanced piston seal 58 through passage 63 to a chamber behind piston 60.
- flow fluid from pump 10 is greater than conditions require, discharge pressure increases.
- the resulting intermediate pressure in passages 56, 63 is increased allowing tilt piston 60 pressure to increase. This pressure increase will move piston 60 to the left in Figure 1, lessen the swash plate angle, thereby decreasing flow.
- the converse of the above description applies when conditions require an increase in flow.
- Piston 60 includes arcuate portions 57 which engage and tilt swash plate 30 around axis 42.
- swash plate 30 When piston 60 is forced to the left as shown in Figure 1, swash plate 30 is moved towards vertical alignment and thereby decreases the stroke of working piston 26.
- Inlet to pump housing 18 is through port 12.
- a thrust plate 38 extends from the center shaft 40.
- Passage 62 is formed in thrust plate 38.
- Thrust plate 38 during operation acts as a centrifugal pump, boosting the pressure of the hydraulic fluids supplied into port 12.
- Thrust plate 38 includes a working surface 64 on which shoes 34 ride as plate 38 rotates. Passage 62 connects to an opening 65 in the working face 64 of thrust plate 38.
- Swash plate 30 includes an opening 66 formed therein.
- opening 66 in swash plate 60 aligns with the opening in show 32, fluid passes through opening 66, shoe 32 and hollow piston 26 into cylinder 24.
- opening 66 passes beyond shoe 32, then shoe 32 seals against working surface 48.
- opening 36 passes beyond shoe 34, then shoe 34 seals against working surface 64 of thrust plater 38.
- Force balancing of the working piston 26 thrust load is accomplished by dummy piston 28, which is placed opposite the working piston 36.
- Dummy piston 28 rides through shoe 34, on thrust plate 38 and transmits negative forces required to balance the positive forces of working piston 26.
- the working surface 34 of thrust plate 38 is used as the dummy piston 28 bearing surface.
- the dummy pistons 28 are used to create an equal force opposite to the force developed by the working pistons 26. This approach saves weight and decreases the envelope size.
- the large bearings as required in prior art high pressure similar type piston pumps are not required.
- the disclosed high pressure variable displacement piston pump will boost an inlet pressure of 103KPa (15 psi) to 55,160KPa (8000 psi) or greater and hold it there under a variety of flow and speed conditions.
- the inlet fluid pressure can be raised as a function of rotational speed by an amount such as 138KPa (20 psi). This avoids cavitation in the pump.
- Each piston pump is fed pressurized fluid through the slot 66 cut in the swash plate 30 and also by the port channel 62 and opening 65 formed in thrust plate 38.
- the rotating swash plate 30 provides the reciprocating action for the working piston 26 assembly.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Reciprocating Pumps (AREA)
- Details Of Reciprocating Pumps (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US81375085A | 1985-12-26 | 1985-12-26 | |
US813750 | 1985-12-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0234006A2 true EP0234006A2 (de) | 1987-09-02 |
EP0234006A3 EP0234006A3 (de) | 1988-01-07 |
Family
ID=25213279
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86116392A Withdrawn EP0234006A3 (de) | 1985-12-26 | 1986-11-26 | Hochdruckpumpe mit veränderlicher Fördermenge |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0234006A3 (de) |
JP (1) | JPS62165585A (de) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0558389A1 (de) * | 1992-02-28 | 1993-09-01 | Hydro Rene Leduc | Hydraulische Kolbenpumpe mit Einlassventilen |
FR2688034A1 (fr) * | 1992-02-28 | 1993-09-03 | Leduc Rene Hydro Sa | Perfectionnement aux pompes hydrauliques a pistons munis de clapet d'aspiration. |
FR2692008A1 (fr) * | 1992-06-05 | 1993-12-10 | Leduc Rene Hydro Sa | Perfectionnement aux pompes hydrauliques à pistons munis de clapets d'aspiration. |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2365309A (en) * | 1943-07-12 | 1944-12-19 | Robert E Barry | High-pressure pump |
DE1095668B (de) * | 1955-04-26 | 1960-12-22 | Fairey Aviat Ltd | Taumelscheibenpumpe |
DE2114841A1 (de) * | 1970-03-31 | 1971-10-14 | Delavan Manufacturing Co West Des Moines Ia (V St A ) | Druckerzeugende Vorrichtung, insbesondere hydraulisch kompensierte Axialkolbenpumpe oder Motor |
DE1703594A1 (de) * | 1967-06-14 | 1972-03-09 | Shimadzu Corp | Axialkolbenpumpe |
US4182365A (en) * | 1977-09-26 | 1980-01-08 | The Bendix Corporation | Control valve for use with variable displacement piston pump |
-
1986
- 1986-11-26 EP EP86116392A patent/EP0234006A3/de not_active Withdrawn
- 1986-12-24 JP JP61316115A patent/JPS62165585A/ja active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2365309A (en) * | 1943-07-12 | 1944-12-19 | Robert E Barry | High-pressure pump |
DE1095668B (de) * | 1955-04-26 | 1960-12-22 | Fairey Aviat Ltd | Taumelscheibenpumpe |
DE1703594A1 (de) * | 1967-06-14 | 1972-03-09 | Shimadzu Corp | Axialkolbenpumpe |
DE2114841A1 (de) * | 1970-03-31 | 1971-10-14 | Delavan Manufacturing Co West Des Moines Ia (V St A ) | Druckerzeugende Vorrichtung, insbesondere hydraulisch kompensierte Axialkolbenpumpe oder Motor |
US4182365A (en) * | 1977-09-26 | 1980-01-08 | The Bendix Corporation | Control valve for use with variable displacement piston pump |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0558389A1 (de) * | 1992-02-28 | 1993-09-01 | Hydro Rene Leduc | Hydraulische Kolbenpumpe mit Einlassventilen |
FR2688034A1 (fr) * | 1992-02-28 | 1993-09-03 | Leduc Rene Hydro Sa | Perfectionnement aux pompes hydrauliques a pistons munis de clapet d'aspiration. |
US5354181A (en) * | 1992-02-28 | 1994-10-11 | Hydro Rene Leduc | Hydraulic piston pumps equipped with suction valve |
FR2692008A1 (fr) * | 1992-06-05 | 1993-12-10 | Leduc Rene Hydro Sa | Perfectionnement aux pompes hydrauliques à pistons munis de clapets d'aspiration. |
Also Published As
Publication number | Publication date |
---|---|
EP0234006A3 (de) | 1988-01-07 |
JPS62165585A (ja) | 1987-07-22 |
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RHK1 | Main classification (correction) |
Ipc: F04B 1/14 |
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STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 19880708 |
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RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: WOODRUFF, FRANK |