Pump assembly for a vehicle braking system with eccentric drive actuator

Abstract

A hydraulic pump assembly 20 of a vehicle braking system includes at least one pair of hydraulic pumps for pumping brake fluid. Each pump 13 has a pump member 14. The pump members 14 of a pair of pumps are disposed in opposing, spaced relation along an axis. An eccentric drive actuator 22 is disposed between the pump members 14 of a pair of pumps so as to move the pump members substantially simultaneously along the axis between first and second positions.

Description

This application is based on U.S. Provisional Application No. 60/651,808, filed on Feb. 10, 2005 and claims the benefit thereof for priority purposes.

FIELD OF THE INVENTION

The invention relates to a vehicle braking system and, more particularly, to an eccentric drive actuator that permits two hydraulic pump members to be actuated simultaneously to pump a hydraulic fluid.

BACKGROUND OF THE INVENTION

With reference to FIG. 1, a conventional hydraulic vehicle brake system is shown generally indicated at 10. The system 10 includes a motor/pump unit with an electric motor having a shaft 12 and a hydraulic pump 14 for delivering brake fluid. The functionality of the hydraulic system 10 is based on fluid flow and pressure. These two characteristics are dependant on the actuation of at least two pump members 14 and 14′ that are diametrically opposed, as shown in FIG. 1. The linear pump actuation is commonly solved with the use of a centrally located eccentric motion that drives the pump members 14 one at a time in the directions E. This motion is accomplished with the use of a centrally located eccentric bearing 16. This eccentric motion causes one of the pump members 14 to be actuated or displaced while the other pump member 14′ is released to be retracted into a pump cylinder cavity.

With this pumping motion, the fluid at the inlet of a hydraulic system is being pressurized and passed through the system to apply proper braking force to wheels of a vehicle. For adequate pressure and fluid flow the degree of eccentricity is varied on the bearing or shaft end. With the conventional system 10 of FIG. 1, the motor sees high forces that create a bending moment on a shaft 12 with each rotation.

There is a need provide a rotating apparatus that actuates both hydraulic pump members of a vehicle braking system substantially simultaneously so as to reduce stress on a motor shaft.

SUMMARY OF THE INVENTION

An object of the invention is to fulfill the need referred to above. In accordance with the principles of the present invention, this objective is achieved by providing a hydraulic pump assembly of a vehicle braking system that includes at least one pair of hydraulic pumps for pumping brake fluid. Each pump has a pump member. The pump members of a pair of pumps are disposed in opposing, spaced relation along an axis. An eccentric drive actuator is disposed between the pump members of a pair of pumps so as to move the pump members substantially simultaneously along the axis between first and second positions.

In accordance with another aspect of the invention, a method of actuating pumps of a vehicle braking system provides at least one pair of hydraulic pumps, each pump having a pump member. The pump members of a pair of pumps are disposed in opposing, spaced relation along an axis. An eccentric drive actuator is provided between the pump members of a pair of pumps so as to contact the pump members. The drive actuator is moved to a first position thereby moving the pump members substantially simultaneously along the axis to a first position to cause the pumps to pump brake fluid.

Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be better understood from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a schematic illustration of a conventional hydraulic pump assembly of a vehicle braking system having eccentric bearing that drives two pump members one at a time.

FIG. 2 is a schematic illustration of hydraulic pump assembly of a vehicle braking system having an eccentric drive actuator provided in accordance with the principles of the invention, for driving at least two pump members substantially simultaneously to a pumping position.

FIG. 3 is a schematic illustration of the hydraulic pump assembly of FIG. 2, shown with the eccentric drive actuator moved to a second position with the pump members in a non-pumping position.

FIG. 4 is an end view of an eccentric drive actuator of provided in accordance with the invention.

FIG. 5 is a perspective view of the eccentric drive actuator of FIG. 4.

FIG. 6 is a perspective view of an eccentric drive actuator of the invention manufactured into rotor shaft.

FIG. 7 is a schematic illustration of the hydraulic pump assembly of FIG. 3, but shown with a bearing device between the actuator and the pump members.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

With reference to FIG. 2, hydraulic pump assembly of a vehicle braking system is shown, generally indicated at 20, in accordance with the principles of the present invention. The system 20 includes at least one pair of hydraulic pumps 13 with each pump 13 having a pump member 14. The pump members 14 of each pair of pumps are disposed in opposing, spaced relation along axis X. Each pump 13 is constructed and arranged to pump a brake fluid for a vehicle braking system such as an antilock braking system (ABS) or a Traction Control braking system. As used herein, “brake fluid” includes any hydraulic fluid that can be used in a vehicle braking system. Linear actuation of the pump members 14 in the directions E (along axis X) is provided by a centrally located eccentric drive actuator 22. The eccentric drive actuator 22 is coupled to a shaft 12 of a motor (not shown) and, upon rotation, actuates both hydraulic pump members 14 substantially simultaneously. The center O of the drive actuator 22 is disposed on axis X. This configuration advantageously equalizes the forces that are pressing onto the motor shaft 12.

In the embodiment of FIG. 2, the forces on shaft 12 are equalized because both pump members 14 are subjecting pressure and force to the shaft 12 at the same time. The drive actuator 22 can be attached to a rotor (e.g. via shaft 12) of a motor by any of the following (however not limited to) methods:

• • 1) Press fit onto the shaft of the rotor
  • 2) Machined surface of the shaft
  • 3) Crimped
  • 4) Welded
  • 5) Bonded

FIG. 4 shows a front view of the eccentric drive actuator 22 and FIG. 5 is a perspective view of the drive actuator 22. The shaft 12 (not shown in FIGS. 4 and 5) is received in a central bore 24.

Alternatively, the shaft 12 and drive actuator 22 can be manufactured together as a one-piece member as shown in FIG. 6. It can be appreciated that any means of providing the drive actuator 22 and shaft 12 features are within the contemplation of this invention.

With reference to FIG. 4, an embodiment of the eccentric drive actuator 22 has two side dimensions A and B. Dimension A defines the maximum movement that would be exhibited by the pump members 14 when engaged by the drive actuator 22. Dimension B defines the minimum or relaxed position of the pump members 14. The drive actuator 22 is in constant direct contact with each pump member 14 and causes the axial displacement of the pump members 14.

As shown in FIG. 4, with reference to center O, by having dimension lines C and C′ equal to each other and dimensions lines D and D′ equal to each other, a pump motion is created in which both pump members 14 move substantially simultaneously between a first position (FIG. 2) causing the pumps 13 to pump brake fluid and a second position (FIG. 3) stopping the pumping of brake fluid. The dimension lines C, C′, D and D′ each extend from a center O of the drive actuator 22 to a point that is tangent with the periphery of the drive actuator 22. Thus, C′+C=B and D+D′=A.

With the use of this equal pump drive actuator 22, the stresses that are exhibited on the shaft 12 of the motor are significantly reduced with regard to the tilting or bending moment of the shaft 12 within the rotor. The drive actuator 22 may be either fabricated from a solid piece of material to act as a wear surface when in direct contact with the pump members, or the actuator 22 can be associated with needle/roller bearings 26 (FIG. 7) that contact the pumping members 14. Alternatively, the pumping members 14 may incorporate the use of a bearing device 26, instead of being associated with a surface of the eccentric drive actuator 22, or the bearing device 26 may be separate from either the pumping members or drive actuator.

The drive actuator 22 provides the following features:

• • 1. The drive actuator 22 will cause both pump members to move simultaneously.
  • 2. Force equalization will occur on the shaft 12 as a result of diametrically opposed pressures.
  • 3. The drive actuator 22 that moves the pump members 14 in the hydraulic system for a vehicle braking system is an integral part of the system.

The foregoing preferred embodiments have been shown and described for the purposes of illustrating the structural and functional principles of the present invention, as well as illustrating the methods of employing the preferred embodiments and are subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within the spirit of the following claims.

Claims

1. A hydraulic pump assembly of a vehicle braking system comprising:

at least one pair of hydraulic pumps for pumping brake fluid, each pump having a pump member, the pump members of a pair of pumps being disposed in opposing, spaced relation along an axis, and

an eccentric drive actuator disposed between the pump members of a pair of pumps so as to move the pump members substantially simultaneously along the axis between first and second positions.

2. The pump assembly of claim 1, wherein the drive actuator has a center that is disposed on the axis, the drive actuator being constructed and arranged to be rotated and having a long side of a certain dimension and a short side of a dimension less than the certain dimension, the long and short sides of the drive actuator being constructed and arranged such rotation of the drive actuator moves the pump members substantially simultaneously between the first and second positions.

3. The pump assembly of claim 2, further comprising a shaft, the drive actuator being coupled with the shaft so that rotation of the shaft rotates the drive actuator.

4. The pump assembly of claim 3, wherein the drive actuator and shaft are constructed and arranged as a one-piece member.

5. The pump assembly of claim 3, wherein the drive actuator includes a bore therein, the shaft being received in the bore.

6. The pump assembly of claim 1, wherein the drive actuator is in direct contact with the pump members.

7. The pump assembly of claim 1, further comprising a bearing device between the drive actuator and each pump member of a pump pair.

8. A hydraulic pump assembly of a vehicle braking system comprising:

at least one pair of hydraulic pumps for pumping brake fluid, each pump having a pump member, the pump members of a pair of pumps being disposed in opposing, spaced relation along an axis, and

means, disposed between the pump members of a pair of pumps, for moving the pump members generally simultaneously along the axis between first and second positions.

9. The pump assembly of claim 8, wherein the means for moving has a center that is disposed on the axis, and is constructed and arranged to be rotated, the means for moving has a long side of a certain dimension and a short side of a dimension less than the certain dimension, the long and short sides of the means for moving being constructed and arranged such rotation of the means for moving moves the pump members substantially simultaneously between the first and second positions.

10. The pump assembly of claim 8, further comprising a shaft, the means for moving being a drive actuator coupled with the shaft so that rotation of the shaft rotates the drive actuator.

11. The pump assembly of claim 10, wherein the drive actuator and shaft are constructed and arranged as a one-piece member.

12. The pump assembly of claim 10, wherein the drive actuator includes a bore therein, the shaft being received in the bore.

13. The pump assembly of claim 8, wherein the means for moving is in direct contact with the pump members.

14. The pump assembly of claim 8, further comprising a bearing device between the means for moving and each pump member of a pump pair.

15. A method of actuating pumps of a vehicle braking system, the method includes:

providing at least one pair of hydraulic pumps, each pump having a pump member, the pump members of a pair of pumps being disposed in opposing, spaced relation along an axis,

providing an eccentric drive actuator between the pump members of a pair of pumps so as to contact the pump members, and

moving the drive actuator to a first position so move the pump members substantially simultaneously along the axis to a first position to cause the pumps to pump brake fluid.

16. The method of claim 15, further including moving the drive actuator to a second position to move the pump members substantially simultaneously to a second position to stop pumping brake fluid.

17. The method of claim 15, wherein the drive actuator is moved by a shaft of a motor.

18. The method of claim 17, wherein the drive actuator and the shaft are integral.

19. The method of claim 17, wherein the drive actuator has a bore and the shaft is fixedly received in the bore.