WO2014138519A1

WO2014138519A1 - Coupling element for a screw pump

Info

Publication number: WO2014138519A1
Application number: PCT/US2014/021518
Authority: WO
Inventors: Marc Hohmann
Original assignee: TI Group Automotive Systems LLC
Current assignee: TI Group Automotive Systems LLC
Priority date: 2013-03-07
Filing date: 2014-03-07
Publication date: 2014-09-12
Anticipated expiration: 2015-09-07

Abstract

In at least some implementations, a fluid pump includes a motor, a rotating member, a drive screw coupled to the rotating member for rotation with the rotating member, a driven screw coupled to the drive screw for rotation with the drive screw so that rotation of the drive screw and driven screw causes fluid to be pumped and a connector. The connector has an engagement feature operably associated with the rotating member and one or more drive features operably associated with the drive screw so that the rotation of the rotating member is transmitted to the drive screw through the connector.

Description

COUPLING ELEMENT FOR A SCREW PUMP

Reference to Co-Pending Application

This application claims the benefit of U.S. Provisional Application No. 61/774,306 filed March 7, 2013, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to a fluid pump including a pumping element driven for rotation by a shaft.

Background

Electric motor driven fluid pumps have been provided with various pumping elements, including meshed gears (e.g. gerotor pumps), impellers and intermeshed screws, and the pumping elements are driven by the motor via a shaft. The shaft engages at least one pumping element directly and the pumping element includes a designed in drive surface for engagement with the motor shaft.

Summary

At least some implementations of a connector for a fluid pump that has a rotating member, a drive screw that is driven for rotation by the rotating member and one or more radially extending threads, includes a base and at least one flange. The base has an engagement feature adapted to be engaged by the rotating member so that the connector is driven for rotation by the rotating member. And the least one flange is carried by the base and adapted to engage a portion of a thread of the drive screw so that the drive screw is rotated when the connector is rotated. In at least some implementations, the drive screw need not have any drive features other than the threads. Brief Description of the Drawings

The following detailed description of preferred embodiments and best mode will be set forth with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary sectional view of a portion of one implementation of a fluid pump;

FIG. 2 is a perspective view of meshed screws from the pump of FIG. 1;

FIG. 3 is a fragmentary side view showing a drive system for the screws including a connector mated with a motor output shaft and the screws;

FIG. 4 is an enlarged, fragmentary perspective view showing the screws and a connector;

FIG. 5 is an end view of the connector and screws of FIG. 4; FIG. 6 is a perspective view of the connector;

FIG. 7 is a fragmentary side view showing a drive system for the screws including a connector mated with a motor output shaft and the screws;

FIG. 8 is an enlarged, fragmentary perspective view showing the screws and a connector;

FIG. 9 is an end view of the connector and screws of FIG. 8; and FIG. 10 is a perspective view of the connector.

Detailed Description of Preferred Embodiments

Referring in more detail to the drawings, FIG. 1 shows a fluid pump 10 including an electric motor 12 and a pumping mechanism 14 driven by the motor 12. In one implementation, the fluid pump 10 is used to pump fuel to an internal combustion engine (not shown). Of course, the fluid pump 10 could be used to pump fluids other than fuel. The motor 12 and pumping mechanism 14 may be contained together within a housing 16. The housing 16 has at least one inlet 18 through which fluid enters the housing and at least one outlet (not shown) through which fluid is discharged under pressure from the pump 10. Fluid may flow within the housing 16 between the inlet and outlet and around the motor 12. This arrangement of the housing 16, motor 12 and pump mechanism 14 is but one of many possibilities and the description of this one arrangement is not intended to limit the innovations set forth herein to any particular fluid pump arrangement.

The motor 12 may be a brush-type or brushless motor (as is shown in FIG. 1) and may be driven by any suitable power source. Power supply to the pump 10 may be controlled in any desired manner, such as to provide a relatively constant output pressure and flow rate or a varied pump output. An output shaft 20 is driven for rotation by the motor 12. The output shaft 20 may extend axially from the motor 12 and have a free end 22 spaced from the motor. The output shaft 20 is operably coupled to or otherwise engaged with the pumping mechanism 14 to drive the pumping mechanism 14. To facilitate driving engagement or coupling with the pumping mechanism 14, a non-circular drive feature 24 may be provided on or coupled to the output shaft 20. In the implementation shown, the drive feature 24 includes one or more flat surfaces formed on an otherwise cylindrical output shaft.

The pumping mechanism 14 may include a pair of meshed gears or screws including a drive screw 26 and a driven screw 28, as shown in FIGS. 1-5. The drive screw 26 is directly coupled to and driven by the output shaft 20 and a driven screw 28 is driven for rotation by virtue of it being meshed with the drive screw 26. Each screw 26, 28 is generally cylindrical, may extend generally parallel to an axis 30 of the output shaft 20 and include one or more helically extending threads 32, 34, respectively. When driven by the motor 12, the screws 26, 28 rotate about parallel axes spaced close enough together that the threads 32, 34 remain meshed throughout rotation of the screws. Gaps between the screws 26, 28 enlarge and ensmall as the screws are rotated, and this creates a pumping action in use. The pumping action introduces fuel into gaps between the screws 26, 28 adjacent to an inlet side 36 (FIG. 1) of the pumping mechanism 14 and forces fuel out from such gaps, under pressure, adjacent to an outlet side 38 of the pumping mechanism 14. The screws 26, 28 typically are formed from hardened, corrosion resistant metal material, at least when the pump 10 is used to pump certain fluids, like automotive or other fuels. One representative type of material is nitrided turning steel containing less than 0.2% carbon. To couple the output shaft 20 with the drive screw 26, a connector 40 is provided. The connector 40 as shown in FIGS. 1-6, may include one or more engagement features 42, which may be non-circular and complementary to the drive feature(s) 24 provided on the output shaft 20 so that the engagement feature 42 is operably associated with the output shaft 20 in assembly. The connector 40 may further include one or more drive features 44 that are operably associated with the drive screw 26. In this way, the connector 40 is driven by the output shaft 20 and in turn drives the drive screw 26 to transmit the rotation of the motor 12 to the drive screw 26. The drive features 44 may engage the drive screw 26 from within one or more threads 32 and, in at least some implementations, need not engage the adjacent axial end 46 of the drive screw 26. Further, the end 46 of the drive screw 26 can be formed without any special features and can simply be flat or otherwise shaped. No slots or other cavity, nor tab or other projection need to be formed on the drive screw 26 as the drive screw need not directly engage and be driven by the output shaft 20.

In one form, the connector 40 includes a base 48 and one or more circumferentially spaced flanges 44. The base 48 may overlie the end 46 of the drive screw 26 and have an engagement feature defined by a noncircular opening 42 through or cavity in the base 48 and adapted to receive the output shaft 20. The flanges 44 define the drive features and are each received in a groove 52 between adjacent thread sections on the drive screw 26. The flanges 44 may extend axially from the base 48, may be shaped for close receipt in the grooves 52 and are radially overlapped by the threads 32. The flanges 44 may depend from a radial periphery of the base 48, may be generally evenly spaced about the base 48 and may be formed in one continuous piece of material with the base. Each flange 44 may engage two adjacent thread sections 32 to permit forces to be transmitted to the drive screw 26 through the flanges 44 in both forward and reverse operation of the pump 10, or one flange 44 may engage the drive screw 26 in forward operation and another flange 44 may engage the drive screw 26 during reverse operation. In the example shown, the drive screw 26 has two threads 32 and two flanges 44 are provided. Only one drive feature or flange may be needed in any given implementation.

The connector 40 can be formed from any material strong and durable enough to transfer the motor torque to the drive screw 26, and also suitable for use with the fluid being pumped. Representative materials include various plastics, which may be reinforced such as with certain fibers or other materials, metals, which may included sintered metals, and combinations of plastic and metal (e.g. overmolded metal). The connector 40 could be molded, stamped, bent or otherwise formed into a desired shape. In at least some implementations, the motor may provide a torque on the connector of between 0.2 and 0.8 Nm. Of course, different motors and pumps may be used and the above range is merely representative of some fluid pump motors that may be used, for example, in automotive applications.

Another representative form of a connector 60 is shown in FIGS. 7-10. In this form, the connector 60 is adapted to engage a different screw structure. Here, the drive screw 26 includes three grooves 62 exposed at its axial end 64 adjacent to the motor 12. The connector 60 includes three flanges 66, one for each groove 62, although this is not necessary. The flanges 66 define the drive features and are interconnected by a base 68 that defines or carries the engagement feature 70 for the output shaft 20. The base 68 overlies the end 64 of the drive screw 26 and the flanges 66 are received between adjacent thread sections 72, to engage the thread sections 72 when the output shaft 20 is rotated. This connector 60 can be formed from the same materials as the previously described connector, and by the same methods. In use, when the motor 12 rotates the output shaft 20, the output shaft 20 engages and rotates the connector 40, 60. The connector 40, 60 in turn engages and rotates the drive screw 26 which engages and rotates the driven screw 28. The rotating screws 26, 28 define the enlarging and ensmalling cavities between them to pump fluid as described above. With the connector 40, 60, the drive screw 26 need not be machined or otherwise formed to include special axially outwardly extending drive features engageable with the output shaft 20. Hence, a less costly drive screw 26, having a substantially flat axial end nearest the motor 12, can be used in the pump, and wear surfaces at an axial end of the drive screw are avoided. Of course, the connector 40, 60 could also be used with a drive screw 26 that is machined or otherwise formed to provide features enabling it to be rotated, if desired. In other words, the lack of machined features on the drive screw is a possibility but not a necessity.

Further, while an output shaft 20 is shown and described above, a rotating portion of the motor 12 (e.g. its rotor) could directly drive the connector 40, 60. In this way, the connector 40, 60 can be considered to be rotated by a rotating member, and that rotating member could, but need not, include an output shaft that is driven by the motor.

While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.

Claims

Claims:

1.

A fluid pump, comprising:

a motor;

a rotating member which may be a portion of the motor itself or a component rotated by the motor;

a drive screw coupled to the rotating member for rotation with the rotating member;

a driven screw coupled to the drive screw for rotation with the drive screw so that rotation of the drive screw and driven screw causes fluid to be pumped; and a connector having an engagement feature operably associated with the rotating member and one or more drive features operably associated with the drive screw so that the rotation of the rotating member is transmitted to the drive screw through the connector.

2.

The pump of claim 1 wherein the connector includes a base that axially overlies an end of the drive screw and includes the engagement feature, and the connector also includes one or more flanges extending from the base and engaging the drive screw to define said one or more drive features.

3.

The pump of claim 2 wherein the base and flanges are formed from the same piece of material.

4.

The pump of claim 1 wherein the drive screw includes an axial end adjacent to the motor that is substantially flat and without any axially outwardly extending drive features that are engaged with the output shaft.

5.

The pump of claim 1 wherein the rotation of the rotating member is transmitted to the drive screw solely through the connector.

6.

The pump of claim 1 wherein the rotating member includes an output shaft coupled to and driven for rotation by the motor.

7.

The pump of claim 2 wherein drive screw includes adjacent thread sections and a groo ve between the thread sections and the flanges are each received in the groove.

8.

The pump of claim 7 wherein the flanges are radially overlapped by the threads sections.

9.

The pump of claim 2 wherein the flanges are evenly spaced about the base and may be formed in one continuous piece of material with the base.

10.

A connector for a fluid pump including a rotating member and a drive screw that is driven for rotation by the rotating member and has one or more radially extending threads, comprising:

a base having an engagement feature adapted to be engaged by the rotating member so that the connector is driven for rotation by the rotating member; and

at least one flange carried by the base and adapted to engage a portion of a thread of the drive screw so that the drive screw is rotated when the connector is rotated.

11.

The pump of claim 10 wherein the drive screw has more than one thread and one flange is provided for each thread of the drive screw.

12.

The pump of claim 11 wherein the flanges are evenly spaced about the base and may be formed in one continuous piece of material with the base.

13.

The pump of claim 10 wherein the flange is radially overlapped by said portion of the thread engaged by said flange.