WO2013038221A1

WO2013038221A1 - Single chamber variable displacement vane pump

Info

Publication number: WO2013038221A1
Application number: PCT/IB2011/002159
Authority: WO
Inventors: Eduardo GUBBIOTTI RIBERIO; Ayres Pinto De Andrade Filho; Joao Luiz De Carvalho Meira
Original assignee: Melling Do Brasil Componentes Automotivos Ltda.
Priority date: 2011-09-16
Filing date: 2011-09-16
Publication date: 2013-03-21

Abstract

A variable displacement vane pump includes a control chamber (40) that is formed between a housing and (14) a pump control ring (28). The control chamber is operable to receive pressurized fluid to create a force to move the pump control ring toward a position of minimum volumetric capacity of the pump. A biasing element (52) between the pump control ring and the housing biases the pump control ring toward a position of maximum volumetric capacity of the pump. The biasing element acts against the force applied to the pump control ring by the pressurized fluid within the control chamber; and a restricted flow path (25) from the fluid outlet (44) to the control chamber, wherein the restricted flow path provides pressurized fluid to the control chamber from the fluid outlet at a lower fluid pressure than the fluid pressure at the fluid outlet.

Description

SINGLE CHAMBER VARIABLE DISPLACEMENT VANE PUMP

Technical Field

[0001] The present invention relates to a variable displacement vane pump, and more specifically, the present invention relates to a variable displacement vane pump which creates two different equilibrium pressures by utilizing a restrictor and bypass valve by supplying fluid to a single control chamber adjacent a control ring.

Background

[0002] Variable displacement vane pumps are well-known and can include a displacement adjusting element in the form of a pump control ring that can be moved to alter the rotor eccentricity of the pump and hence alter the volumetric capacity of the pump. If the pump is supplying a system with a substantially constant orifice size, such as an automobile engine lubrication system, changing the output volume of the pump is equivalent to changing the pressure produced by the pump.

[0003] Having the ability to alter the volumetric capacity of the pump to maintain an equilibrium pressure is important in environments such as automotive lubrication pumps, wherein the pump will be operated over a range of operating speeds. In order to maintain an equilibrium pressure in such environments, it is known to utilize a feedback supply of the working fluid {e.g., lubricating oil) from the output of the pump to a control chamber adjacent the pump control ring, the pressure in the control chamber acting to move the control ring, typically against a biasing force from a return spring, to alter the capacity of the pump.

[0004] When the pressure at the output of the pump increases, such as when the operating speed of the pump increases, the increased pressure is applied to the control ring to overcome the bias of the return spring and to move the control ring to reduce the capacity of the pump, thus reducing the output volume and hence the pressure at the output of the pump. [0005] Conversely, as the pressure at the output of the pump drops, such as when the operating speed of the pump decreases, the decreased pressure applied to the control chamber adjacent the control ring allows the bias of the return spring to move the control ring to increase the capacity of the pump, raising the output volume and hence pressure of the pump. In this manner, an equilibrium pressure is obtained at the output of the pump. The equilibrium pressure is determined by the area of the control ring against which the working fluid and the control chamber acts, the pressure of the working fluid supplied to the chamber, and the bias force generated by the return spring.

[0006] Conventionally, the equilibrium pressure is selected to be a pressure which is acceptable for the expected operating range of the engine and is thus somewhat of a compromise, as, for example, the engine may be able to operate acceptably at lower operating speeds with a lower working fluid pressure than is required at higher operating engine speeds. To prevent undue wear or other damage to the engine, the engine designers will select an equilibrium pressure for the pump which meets the worse case (high operating speed) conditions. Thus, at lower speeds, the pump will be operating at a higher capacity than necessary for those speeds, wasting energy pumping the surplus, unnecessarily, working fluid.

[0007] It is also known to utilize more than one control chamber in order that more than one equilibrium pressure can be established within the pump. However, by establishing multiple control chambers, the pump must take on a greater size physically, thereby requiring the pump to have a larger overall size. A larger sized pump can limit the applications by which the pump can be utilized within an automobile engine compartment. In addition, the multiple control chambers require additional machining and parts, such as seals, thereby increasing the cost of such designs as compared to single chamber designs.

[0008] It is desirable to have a variable displacement vane pump, which can provide at least two selectable equilibrium pressures with a single control chamber in a reasonably compact pump housing. Summary

A variable displacement vane pump taught herein has a housing with a pump chamber having a fluid inlet and a fluid outlet, a pump control ring disposed within the housing for altering the displacement of the pump, and a vane pump rotor rotatably mounted within the pump control ring. The vane pump rotor has a plurality of slidably mounted vanes engaging an inside surface of the pump control ring. The vane pump rotor having an axis of rotation eccentric from a center of the pump control ring. The vane pump rotor rotates to pressurize fluid as the fluid moves from the fluid inlet to the fluid outlet.

A control chamber that is formed between the housing and the pump control ring. The control chamber is operable to receive pressurized fluid to create a force to move the pump control ring toward a position of minimum volumetric capacity of the pump. A biasing element between the pump control ring and the housing biases the pump control ring toward a position of maximum volumetric capacity of the pump. The biasing element acts against the force applied to the pump control ring by the pressurized fluid within the control chamber; and a restricted flow path from the fluid outlet to the control chamber, wherein the restricted flow path provides pressurized fluid to the control chamber from the fluid outlet at a lower fluid pressure than the fluid pressure at the fluid outlet.

Brief Description of the Drawings

[0009] The various features, advantages and other uses of the present apparatus will become more apparent by referring to the following detailed description and drawing in which:

[0010] FIG. 1 is a perspective view showing a variable displacement vane pump and an automotive oil sump reservoir;

[0011] FIG. 2 is an exploded perspective view showing the variable displacement vane pump and the automotive oil sump reservoir of FIG. 1; [0012] FIG. 3 is an illustration showing a control ring of the variable displacement vane pump in a maximum displacement position with a bypass valve closed;

[0013] FIG. 4 is an illustration showing a control ring of the variable displacement vane pump in a minimum displacement position with a bypass valve closed;

[0014] FIG. 5 is an illustration showing a control ring of the variable displacement vane pump in a maximum displacement position with a bypass valve open;

[0015] FIG. 6 is an illustration showing a control ring of the variable displacement vane pump in a minimum displacement position with a bypass valve open;

[0016] FIG. 7 shows a first example of a calibrated orifice;

[0017] FIG. 8 shows a second example of a calibrated orifice;

[0018] FIG. 9 is a diagram showing operation of the pump with the bypass valve closed; and

[0019] FIG. 10 is a diagram showing operation of the pump with the bypass valve open.

Detailed Description

[0020] The present invention provides a pump 10, which is a variable displacement vane pump, as illustrated in FIGS. 1-8. As seen in FIGS. 1 and 2, the pump 10 may be utilized to pump a fluid, such as automotive engine lubricant. In the illustrated example, the pump 10 is a variable displacement vane pump. In such applications, the pump 10 may be connected to an automotive oil sump reservoir 12. A housing 14 of the pump 10 may provide a back side 16, a midsection 18, and a cover 20. A plate 22 mounted between the back side 16 and the midsection 18 of the housing 14 may contain a calibrated orifice 24 and valve 26, as will be described further in the specification. A pump control ring 28 is pivotally connected to the housing 14 through the use of a pivot pin 30 and a needle bearing 32. A vane pump rotor 34 is mounted within the pump control ring 28. The vane pump rotor 34 has a plurality of vanes 36 that are mounted for sliding within slots. The vanes 36 engage an inside surface of the pump control ring 28, and the vanes 36 slide within the slots in response to movement of the pump control ring 28 with respect to the rotor. The vane pump rotor 34 has an axis of rotation eccentric from a center of the pump control ring 28, as will be described further herein. A drive shaft 38 is driven by any suitable means, such as an automotive engine or other mechanism to which the pump is to supply working fluid to operate the pump 10. The drive shaft 38 engages the vane pump rotor 34 and rotates the vane pump rotor 34 as the drive shaft 38 is driven.

[0021] As seen in FIGS. 3-6, the pump control ring 28 is mounted within the housing 14 via the pivot pin 30, which allows the center of the pump control ring 28 to move relative to the center of the vane pump rotor 34. The needle bearing 32 is mounted between the pivot pin 30 and the pump control ring 28 so as to provide easy pivoting of the pump control ring 28 relative to the pivot pin 30. The center of the pump control ring 28 is located eccentrically with respect to the center of the vane pump rotor 34, as both the interior of the pump control ring 28 and the vane pump rotor 34 are substantially circular in shape. A control chamber 40 is formed within a space created between the pump control ring 28 and an interior surface of the housing 14. The control chamber 40 is in communication with a fluid outlet 44 of the housing 14. A pair of seals 46, 48 are mounted within recesses in the pump control ring 28 and engage an inner surface of the housing 14 so as to seal the control chamber 40.

[0022] In order to vary the displacement of fluid being pumped through the pump 10, the vane pump rotor 34 pumps fluid from a fluid inlet 42 of the housing 14 through a working fluid chamber 50 and through to the fluid outlet 44. The volume of the working fluid chamber 50 changes as the pump control ring 28 pivots about pivot pin 30. The volume of the working fluid chamber 50 becomes greatest when the pump control ring 28 is in the position as shown in FIGS. 3 and 5. This position allows for the greatest amount of fluid to be pumped to the fluid outlet 44. When the pump control ring 28 rotates to a position shown in FIGS. 4 and 6, the volume of the working fluid chamber 50 decreases, and the amount of fluid pumped to the fluid outlet 44 is decreased. [0023] As seen in FIGS. 3-6, a compression spring 52 is mounted between the pump control ring 28 and the housing 14, thereby biasing the pump control ring 28 toward a maximum displacement position, as shown in FIGS. 3 and 5. The working fluid chambers 50 between the vanes 36 have their volumes change as the vane pump rotor 34 rotates, and thus, the changing of the volume in the working fluid chambers 50 generates the pumping action of the pump 10, thereby drawing fluid from the inlet port 42 and pressurizing and delivering it to the fluid outlet 44. Thus, the fluid inlet 42 side of the pump 10 is the low pressure side of the pump 10, and the fluid outlet 44 side of the pump 10 is the high pressure side of the pump 10. By moving the pump control ring 28 about pivot pin 30, the amount of eccentricity relative to the vane pump rotor 34 can be changed to vary the amount by which the volume of the working fluid chambers 50 change from the low pressure side of the pump 10 to the high pressure side of the pump 10, thereby changing the volumetric capacity of the pump 10.

[0024] In order to adjust the displacement of the pump 10, the control chamber 40 is formed between the housing 14 and the pump control ring 28, as seen in FIGS. 3-6. The control chamber 40 is filled with the working fluid. In particular, the control chamber can be filled with pressurized working fluid that is supplied from fluid outlet 44, such that pressurized working fluid from the pump 10 that is supplied to the fluid outlet 44 also fills the control chamber 40. Of course, the control chamber 40 need not be in direct fluid communication with the fluid outlet 44, but rather could be supplied with working fluid from suitable source. The pressurized working fluid in the control chamber 40 acts against the pump control ring 28, and when the force on the pump control ring 28 resulting from the pressure of the pressurized working fluid within the control chamber 40 is sufficient to overcome the biasing force of the spring 52, the pump control ring 28 pivots about pivot pin 30 toward the minimum displacement position, thereby reducing the eccentricity of the pump 10, as seen in FIGS. 4 and 6. When the pressure of the pressurized working fluid is not sufficient to overcome the biasing force of the spring 52, the pump control ring 28 pivots downward against the housing 14 toward the maximum displacement position, thereby increasing the eccentricity of the pump, as seen in FIGS. 3 and 5.

[0025] In order to effectively control the displacement of the pump 10 over a broad range of operating speeds, the pump 10 is configured to deliver the working fluid to the control chamber 40 by way of at least two different paths, corresponding to different pressures. An unrestricted flow path 55 (FIGS. 9-10) provides fluid communication between the fluid outlet 44 and the control chamber 40. The unrestricted flow path 55 terminates at a control port 54 that is formed in the plate 22 at the control chamber 40. The unrestricted flow path 55 is configured such that the pressurized working fluid is supplied to the control chamber 40 along the unrestricted flow path 55 at the same pressure as exists at the fluid outlet 44.

[0026] A valve 26, such as a electronic solenoid-operated valve, is provided to selectively establish and disrupt fluid communication along the unrestricted flow path 55. The valve 26 can be controlled by an engine control system. The valve 26 is interposed between the fluid outlet 44 and the unrestricted flow path 55 to selectively open and closed fluid

communication between the fluid outlet 44 and the control chamber 40 along the unrestricted flow path 55. In FIGS. 3-4, the valve 26 is closed, substantially preventing fluid communication between the fluid outlet 44 and the control chamber 40 along the unrestricted flow path 55. In FIGS. 5-6, the electronic valve 55 is open, allowing fluid communication between the fluid outlet 44 and the control chamber 40 along the unrestricted flow path 55.

[0027] A restricted flow path 25 also provides fluid communication between the fluid outlet 44 and the control chamber 40. The calibrated orifice 24 is provided along or at one end of the restricted flow path 25. In the illustrated example, as shown in FIGS. 3-6, the calibrated orifice 24 is formed in the plate in the plate 22 so as to restrict the amount of fluid passing to the control chamber 40 from the fluid outlet 44. By creating such a restriction, the pressure of the working fluid that is provided to the control chamber 40 along the restricted flow path 25 is lowered relative to the pressure at the fluid outlet 44. In addition, the amount of pressure generated in the control chamber 40 can be adjusted or manipulated by simply calibrating the size of the orifice 24.

[0028] One example of the calibrated orifice 24 is shown in FIG. 7. Here, the calibrated orifice 24 is formed through the plate 22 at the control chamber 40, where the restricted flow path 25 ends. Another example of the calibrated orifice 24 is shown in FIG. 8. Here, the calibrated orifice 24 is positioned along the restricted flow path 25. In both cases, outlet pressure P3 from the fluid outlet 44 drops to pressure P2 when the working fluid passes through the calibrated orifice 24. These examples assume that the valve 26 is closed.

[0029] When the valve 26 is closed, as in FIGS. 3-4, the restricted flow path 25 can be the sole or primary source of fluid pressure to the control chamber 40. As a result, with the unrestricted flow path 55 closed by the valve 26, the fluid pressure within the control chamber is less than the pressure of the working fluid at the fluid outlet 44, but greater that than the pressure of the working fluid at the fluid inlet 42. When the valve 26 is open, the fluid pressure within the control chamber 40 is substantially equal to the pressure of the working fluid at the fluid outlet 44 of the pump 10.

[0030] As seen in FIG. 9, when the valve 26 is in the off or closed position, the working fluid is provided to the control chamber 40 solely or primary along the restricted flow path 25, and the calibrated orifice 24 decreases the pressure of the working fluid in the control chamber 40 as compared to the pressure at the fluid outlet 44. As shown in FIG. 10, in When the valve 26 is in the open position, the working fluid is provided along the unrestricted flow path 55 and through the control port 54, thereby equalizing or substantially equalizing the pressure in the control chamber 40 as compared to the pressure of the working fluid at the fluid outlet 44.

[0031 ] As an example, at low operating speeds of the pump 10, pressurized working fluid is provided in the control chamber 40, and the pump control ring 28 may be moved to a position wherein the capacity of the pump 10 produces a first, lower equilibrium pressure which is acceptable at low operating speeds. When the pump 10 is driven at higher speeds, the valve 26 may open to increase the pressure in the control chamber 40, thereby establishing a second equilibrium pressure for pump 10, which may be higher than the first equilibrium pressure.

[0032] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments, but to the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is performed under the law.

Claims

CLAIMS What is claimed is:

1. A variable displacement vane pump having a housing with a pump chamber having a fluid inlet and a fluid outlet, a pump control ring disposed within the housing for altering the displacement of the pump, a vane pump rotor rotatably mounted within the pump control ring, and said vane pump rotor having a plurality of slidably mounted vanes engaging an inside surface of the pump control ring, the vane pump rotor having an axis of rotation eccentric from a center of the pump control ring, the vane pump rotor rotating to pressurize fluid as the fluid moves from the fluid inlet to the fluid outlet, comprising:

a control chamber formed between the housing and the pump control ring, and said control chamber operable to receive pressurized fluid to create a force to move said pump control ring toward a position of minimum volumetric capacity of said pump; a biasing element between said pump control ring and the housing, and said biasing element biasing said pump control ring toward a position of maximum volumetric capacity of said pump, and the biasing element acting against the force applied to said pump control ring by said pressurized fluid within said control chamber; and

a restricted flow path from said fluid outlet to said control chamber, wherein the restricted flow path provides pressurized fluid to said control chamber from said fluid outlet at a lower fluid pressure than the fluid pressure at the fluid outlet.

2. The variable displacement vane pump stated in claim 1, further comprising: an unrestricted flow path from said fluid outlet to said control chamber; and a valve for opening and closing said unrestricted flow path, the valve moveable between a closed position, wherein fluid is prevented from passing through said unrestricted flow path, and an open position, wherein fluid flow passes through said unrestricted flow path, thereby substantially equalizing the fluid pressure in said control chamber with the fluid pressure at said fluid outlet.

3. The variable displacement vane pump stated in claim 2, wherein closing said valve lowers the fluid pressure in said control chamber.

4. The variable displacement vane pump stated in claim 2, wherein said valve is electronic.

5. The variable displacement vane pump stated in claim 1, wherein said restricted passageway inlcudes a calibrated orifice.

6. The variable displacement vane pump stated in claim 1, further comprising: a needle bearing mounted between said pump control ring and said housing to allow said pump control ring to pivot relative to said needle bearing.