Overmolded brush cover for flexible fuel pumps and gasoline fuel pumps

Abstract

An improved end cap assembly for a fuel pump is provided. The end cap assembly includes a first brush cap and a second brush cap herein overmolded onto a first shunt wire and a second shunt wire to ensure a fluid seal around the shunt wires without the need to thermally weld, acoustically weld, or melt flow the end cap onto the shunt wires. The brush cover is tapered and includes a snap feature that holds the brush cover in place during transportation prior to assembly of the end cap assembly to the fuel pump body.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. patent application No. 17 / 835,438, filed on June 8, 2022, the disclosure of which is incorporated by reference in its entirety. Technical Field

[0003] The present invention relates to fuel system components, and more particularly, to an end cover assembly for an electric fuel pump. Background Art

[0004] Fuel systems for gasoline engines and flexible fuel engines can include a lift pump within the fuel tank. The lift pump is an electric submersible pump that provides fuel to a high-pressure fuel pump at the vehicle engine. Known lift pumps include a brush-type (e.g., DC) motor within a cylindrical pump housing. The pump housing is sealed at its open end by an end cap assembly, and the end cap assembly includes a pair of electrical terminals for connecting to a wiring harness. The electrical terminals transmit a DC voltage (e.g., 12V) from the wiring harness to a pair of DC motor brushes within the housing, thereby powering the motor.

[0005] An example of a known lift pump is disclosed in U.S. Patent 9,470,181 to Fischer. The DC motor brushes in this example are spring biased to maintain good contact with the motor armature. The lift pump includes a pair of flexible shunt wires for connecting electrical terminals to respective brushes. The shunt wires are typically sealed and retained by melting end cap plastic around the free ends of the shunt wires. However, heat staking the shunt wires requires additional processing time and equipment, increasing the overall cost of the lift pump.

[0006] Therefore, there is still a need for an improved end cap assembly that minimizes the processing time and equipment required for assembly. Specifically, there is still a need for an improved end cap assembly that does not require heat staking of shunt wires while maintaining a fluid seal around the extended electrical terminals. Summary of the invention

[0007] An end cap assembly is provided for a fuel pump, such as a submersible lift pump. The end cap assembly includes a first plug and a second plug (referred to herein as a brush cap) that are overmolded onto a first shunt line and a second shunt line for ensuring a fluid seal around the shunt line without requiring the end cap to be heat welded, sonic welded, or melt-flowed onto the shunt line. The brush cap is tapered and includes a snap-fit ​​feature that holds the brush cap in place during transportation before the end cap assembly is assembled to a fuel pump body.

[0008] In one embodiment, the end cap assembly includes a positive electrical terminal and a negative electrical terminal extending from respective connector towers extending upwardly from the end cap. Each connector tower defines an elongated opening extending completely through the end cap. An overmolded shunt wire, a spring, and a brush are housed within each elongated opening. The spring is axially positioned between the brush and the brush cover, and the spring biases the brush into direct electrical contact with a commutator housed in the fuel pump.

[0009] In another embodiment, a manufacturing method is provided. The method includes placing a section of a shunt wire into a mold cavity formed between two half molds. The method then includes injecting a coating resin (e.g., a nylon resin) into the mold cavity, which has the shape of a brush cover. After curing, the overmolded brush cover includes a truncated cone portion and an annular lip. The truncated cone portion includes a tapered outer side wall, and the outer diameter of the annular lip is greater than the inner diameter of the uppermost end of the elongated opening. The annular lip includes a tapered circumferential edge so that the brush cover can be fully seated in the elongated opening during assembly.

[0010] In another embodiment, the brush cover is overmolded onto the shunt wire and the power conductor, and the wire gauge of the power conductor is smaller than the wire gauge of the shunt wire. In yet another embodiment, after the brush cover is overmolded onto the free end of the shunt wire, the power conductor can be inserted into the hole of the brush cover to contact the shunt wire. The area directly below the end cap assembly includes a high pressure chamber. The high pressure fuel causes the brush cover to engage the inclined side wall of the elongated opening, causing the elongated opening to be sealed due to compression. In addition, the annular lip holds the brush cover in place during transportation before the end cap assembly is assembled into the fuel pump body.

[0011] These and other features of the invention will be more fully understood and appreciated by reference to the description of the embodiments and the accompanying drawings.

[0012] Before describing the embodiments of the present invention in detail, it should be understood that the present invention is not limited to the details of the operation details or the construction and arrangement of the parts set forth in the following description or shown in the accompanying drawings. The present invention can be implemented in various other embodiments and can be practiced or performed in alternative ways not explicitly disclosed herein. In addition, it should be understood that the wording and terminology used herein are for the purpose of description and should not be considered as restrictive. The use of "include" and "comprise" and its variations is intended to cover the items listed thereafter and their equivalents and additional items and their equivalents. In addition, enumeration can be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be interpreted as limiting the present invention to any specific order or number of parts. The use of enumeration should also not be interpreted as excluding from the scope of the present invention any additional steps or parts that can be combined with the steps or parts listed or combined into the steps or parts listed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a perspective view of an end cover assembly for a lift pump according to a first embodiment of the present invention.

[0014] Figure 2 yes Figure 1 A cross-sectional view of an end cap assembly showing a tapered brush cover overmolded onto a first shunt wire and a second shunt wire.

[0015] Figure 3 is a close up view of the tapered brush cover that has been overmolded onto the shunt wire.

[0016] Figure 4 is a perspective view of an end cover assembly for a lift pump according to a second embodiment of the present invention.

[0017] Figure 5 yes Figure 4 A cross-sectional view of an end cap assembly is shown, showing a tapered end cap overmolded onto a first shunt wire and a second shunt wire and a power conductor.

[0018] Figure 6 is a close up view of the tapered brush cover that has been overmolded onto the shunt and power leads. DETAILED DESCRIPTION

[0019] Now refer to the attached Figures 1 to 6 An exemplary embodiment of an end cap assembly for a fuel pump is described. As described below, the end cap assembly generally includes first and second brush covers overmolded onto first and second shunt wires, the brush covers ensuring a fluid seal around the extended shunt wires, the free ends of the shunt wires including electrical terminals for connection to a wiring harness. The end cap assembly can be used in connection with a variety of fuel pumps, including the fuel pump disclosed in Fischer's U.S. Patent No. 9,470,181, the disclosure of which is incorporated by reference in its entirety.

[0020] First reference Figures 1 to 3The end cap assembly 10 is adapted to be connected to a cylindrical pump housing and includes an end cap 12 having a first fitting 14 and a second fitting 16 and a first connector tower 18 and a second connector tower 20. The first fitting 14 and the second fitting 16 extend upwardly from the end cap 12 and are attachable to a fuel delivery line such that the first fitting 14 includes a fuel inlet and the second fitting 16 includes a fuel outlet. The first connector tower 18 and the second connector tower 20 extend upwardly from the end cap 12 and define an elongated opening 22 extending completely through the end cap 12 from a first side of the end cap 12 to a second side of the end cap 12. The elongated opening 22 includes a brush cover retainer 24, a spring retainer 26, and a brush retainer 28. The brush cover retainer 24 receives a brush cover 30, the spring retainer 26 receives a spring 32, and the brush retainer 28 receives a motor brush 34 for electrically connecting to a commutator of a motor armature. The end cap 12 includes a cover plate 36 and a downwardly terminating skirt 38 , both of which are integrally formed with the fittings 14 , 16 and the towers 18 , 20 .

[0021] As described above, each connector tower 18, 20 includes a brush 34, a brush spring 32, a shunt wire 40, and a brush cover 30. The brush 34 is housed in the brush housing portion 28 of the elongated opening 22 and contacts the commutator under the action of the brush spring 32. The brush 34 is allowed to move axially within the brush housing portion 28 of the elongated opening 22 to maintain a direct electrical connection with the commutator. The brush spring 32 is housed in the spring retaining portion 26 of the elongated opening 22. The brush spring 32 is axially positioned between the brush 34 and the brush cover 30. A first end of the brush spring 32 engages with the brush 34, and a second end of the brush spring 32 engages with an annular rest portion 42 that separates the spring retaining portion 26 and the brush cover retaining portion 24. The brush cover retaining portion 24 includes a tapered sidewall that narrows as it transitions upward. As described below, high pressure fuel within the fuel pump seals the brush cover 30 against the brush cover retaining portion 24 (tapered sidewall) of the elongated opening 22 , thereby preventing fuel from escaping from the elongated opening 22 .

[0022] Continue as Figure 2As shown, the shunt wire 40 extends from the brush 34 and extends from the corresponding tower 18, 20. The brush cover 30 is overmolded on the middle portion of the shunt wire 40 so that the free end of the shunt wire 40 includes an electrical terminal. For example, the middle portion of the copper shunt wire can be placed in a mold cavity formed between two half molds, and the overmolding resin can be injected into the mold cavity, which has the shape of the brush cover. Optionally, the overmolding resin is a nylon resin, which is oil-resistant and is commonly used in automotive applications. The resulting brush cover 30 includes a truncated cone portion 44 and an annular lip 46. The truncated cone portion 44 includes a tapered outer side wall, and the outer diameter of the annular lip 46 is greater than the inner diameter of the uppermost end of the elongated opening 22. The annular lip 46 includes a tapered circumferential edge so that during installation, the brush cover 30 is inserted through the entrance of the elongated opening, thereby preventing the brush cover 30 from retracting.

[0023] The area directly below the end cap assembly 10 includes a high pressure chamber, so the base 48 of the brush cover 30 is subjected to relatively high pressure fuel. The high pressure fuel forces the brush cover 30 to engage the tapered sidewalls of the elongated opening 22, so that the elongated opening 22 is sealed due to compression without the need to heat weld, sonic weld, or melt flow the end cap onto the shunt line 40.

[0024] Now refer to Figures 4 to 6 , an end cap assembly according to a second exemplary embodiment is shown and generally indicated at 50 . Figures 4 to 6 The end cap assembly 50 of the embodiment of the present invention is similar in structure and function to the end cap assembly 10, except that the brush cover 30 is overmolded onto the shunt wire 40 and the power conductor 52, and the wire gauge of the power conductor 52 is lower than the wire gauge of the shunt wire 40. For example, the free end of the shunt wire 40 and the free end of the power conductor 52 can be welded together and placed in a mold cavity formed between two half molds. The overmolding resin is then injected into the mold cavity, which has the shape of the brush cover. The resulting brush cover 30, and in particular the frustoconical portion 44 of the brush cover 30, is overmolded onto the shunt wire 30 and the power conductor 52. Alternatively, after the brush cover 30 is overmolded onto the free end of the shunt wire 40, the power conductor can be inserted into the hole in the brush cover 30. In each case, the frustoconical portion 44 includes a tapered outer side wall that abuts the tapered side wall of the brush cover retaining portion 24 of the elongated opening 22. The brush spring 32 directly engages the base 48 of the brush cover 30 , and the spring retaining portion 26 of the elongated opening 22 is a continuous extension of the brush cover retaining portion 24 , wherein the brush cover 30 is enlarged to accommodate the lower gauge power conductor 50 .

[0025] In use, the area directly below the end cap assembly 50 includes a high pressure chamber, so the base 48 of the brush cover 30 is subjected to relatively high pressure fuel. The high pressure fuel forces the brush cover 30 to engage the tapered sidewalls of the elongated opening 22, so that the elongated opening 22 is sealed due to compression without the need to heat weld, sonic weld or melt flow the end cap onto the shunt line 40. In addition, the annular lip 46 is provided with a snap feature that can keep the brush cover 30 in place during transportation before the end cap assembly 50 is assembled to the fuel pump body.

[0026] The above description is a description of the current embodiment of the present invention. Various changes and modifications may be made without departing from the spirit and broader aspects of the present invention. The present disclosure is presented for illustrative purposes and should not be construed as an exhaustive description of all embodiments of the present invention, or as limiting the scope of any claim to the specific elements shown or described in conjunction with the present embodiment. Any reference in the singular, such as the use of the articles "one", "a kind", "the" or "said", should not be construed as limiting the element to the singular. In addition, the terms "upper", "lower", "above", "below", etc. are intended to make the information clear when describing the embodiments shown in the accompanying drawings, and should not be understood as limiting the relationship between the geometric features of the present invention.

Claims

1. An end cover assembly for a fuel pump, the end cover assembly comprising: an end cap including a first elongated opening and a second elongated opening extending completely through the end cap, the first elongated opening and the second elongated opening being laterally spaced from one another; a positive terminal and a negative terminal, the positive terminal extending from the first elongated opening, the negative terminal extending from the second elongated opening, the positive terminal comprising a free end of a first shunt wire, and the negative terminal comprising a free end of a second shunt wire; as well as A first brush cover and a second brush cover, the first brush cover is overmolded onto the first shunt wire, the second brush cover is overmolded onto the second shunt wire, the first brush cover and the second brush cover each include a tapered plug having an annular lip at an uppermost portion thereof.

2. The end cap assembly according to claim 1, wherein: The annular lip includes a tapered circumferential edge having an outer diameter greater than an inner diameter of the elongated opening.

3. The end cap assembly according to claim 2, further comprising: a first brush coupled to the first shunt wire and biased downwardly by a first spring, and A second brush is coupled to the second shunt wire and is biased downward by a second spring.

4. The end cap assembly according to any one of claims 1 to 3, wherein: Each of the first elongated opening and the second elongated opening includes a brush cover holding portion, a spring holding portion, and a brush holding portion.

5. The end cap assembly according to claim 4, wherein: The brush cover retaining portion includes a tapered sidewall for engaging the tapered plug.

6. The end cap assembly of claim 4, further comprising an annular rest portion located between the spring retaining portion and the brush cover retaining portion.

7. The end cap assembly according to any one of claims 1 to 6, wherein: The end cap includes a first fitting for a first fuel delivery line and a second fitting for a second fuel delivery line.

8. The end cap assembly according to any one of claims 1 to 7, wherein: The end cap includes first and second connector towers defining the first and second elongated openings, respectively.

9. The end cap assembly according to any one of claims 1 to 7, wherein: The first brush cover and the second brush cover are formed of thermoplastic resin.

10. An end cover assembly for a fuel pump, the end cover assembly comprising: an end cap including a first elongated opening and a second elongated opening extending completely through the end cap, the first elongated opening and the second elongated opening being laterally spaced from one another; a first power conductor and a second power conductor, the first power conductor extending from the first elongated opening, the second power conductor extending from the second elongated opening, the first power conductor being electrically connected to a first shunt line, and the second power conductor being electrically connected to a second shunt line; as well as A first brush cover and a second brush cover, the first brush cover is overmolded onto the first shunt wire, the second brush cover is overmolded onto the second shunt wire, the first brush cover and the second brush cover each include a tapered plug having an annular lip at an uppermost portion thereof.

11. The end cap assembly according to claim 10, wherein: The first brush cover extends around a proximal portion of the first power conductor, and wherein the second brush cover extends around a proximal portion of the second power conductor.

12. The end cap assembly according to any one of claims 10 to 11, wherein: The annular lip includes a tapered circumferential edge.

13. The end cap assembly according to any one of claims 10 to 12, further comprising: a first brush coupled to the first shunt wire and biased downwardly by a first spring, and A second brush is coupled to the second shunt wire and is biased downward by a second spring.

14. The end cap assembly according to any one of claims 10 to 14, wherein: Each of the first elongated opening and the second elongated opening includes a brush cover holding portion, a spring holding portion, and a brush holding portion.

15. The end cap assembly of claim 14, wherein: The brush cover retaining portion includes a tapered sidewall for engaging the tapered plug.

16. The end cap assembly of claim 15, wherein: The spring holding portion is a continuous extension of the brush cover holding portion.

17. A method for manufacturing an end cap assembly: overmolding a tapered plug onto a portion of the shunt line; and The overmolded tapered plug is inserted into the elongated opening in the fuel pump end cover.

18. The method according to claim 17, wherein: Overmolding the tapered plug onto the segment of the flow divider line includes: (a) positioning the segment of the flow divider line in a mold cavity, and (b) injection molding a resin into the mold cavity, the mold cavity having the shape of the tapered plug.

19. The method according to any one of claims 17 to 18, wherein: The resin includes a thermoplastic resin or a thermosetting resin.

20. The method according to any one of claims 17 to 19, wherein: The tapered plug includes an annular lip at an uppermost portion thereof.

Images