Fuel pump for direct fuel injection for internal combustion engines.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- PHINIA DELPHI LUXEMBOURG SARL
- Filing Date
- 2022-07-15
- Publication Date
- 2026-07-31
AI Technical Summary
Existing fuel pumps for direct fuel injection in internal combustion engines have complex assembly operations and high production costs due to precise machining of conical surfaces and the risk of missing parts during assembly.
A fuel pump design featuring a retaining washer with flexible fingers that connect to a circular groove on the piston, allowing for simple and reliable assembly without additional parts, using cutting and stamping operations, and ensuring high retention force through finger inclination and balanced distribution.
The new design simplifies assembly, reduces production costs, and eliminates the risk of missing parts, while maintaining a high retention force through flexible finger engagement in the groove.
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Abstract
Description
Description Title of the invention: Fuel pump for direct injection of fuel for internal combustion engines. Technical field
[0001] = The invention relates to a fuel pump for direct fuel injection for internal combustion engines. Prior art
[0002] — Fuel systems in modern internal combustion engines powered in gasoline, especially those for the automotive market, use direct injection gasoline in which fuel injectors are used to inject the fuel directly into the engine's combustion chambers. In such direct injection systems, the fuel from the tank is supplied by a low-pressure fuel pump integrated into the tank. This low-pressure pump is generally electric and powers a high pressure pump which includes ty- a movable pump piston is inserted into a pump body. The pump piston is actuated by a camshaft of the internal combustion engine so as to raise the fuel pressure in a pumping chamber of the pump body. The fuel under high pressure is then distributed to the injectors which control injecting fuel directly into the combustion chamber of the engine.
[0003] Document EP 3 715 619 A1 shows an example of a pump of this type. An example is also reproduced in [Fig.1]. The movement of the piston 101 in the chamber of pumping 1050 is provided by the camshaft 102 against a spring 103 which tends to keep one end of the piston 101 pressing on a cam of the camshaft 102. The spring is of the helical compression type and is supported on one side by a seat 104 fixed on the body 105 of the pump and on the other hand on a retaining washer 106 of retainer connected to the end of the piston 101 by connecting means 107. The means of connection comprises two conical half-rings 1071 engaged with an imprint 1072 at the end of the piston and a conical housing 1073 carried by the washer of retainer 106 in which the conical half-rings 1071 are housed. The slope of the cone of the housing 1073 is oriented such that the action of the spring 103 on the retaining washer 106 is blocked by the wedged conical half-rings 1071 in accommodation 1073.
[0004] …— Even if these means of restraint are effective, they have some drawbacks. We can see that the assembly operations are complex. It is indeed necessary Place the spring and retaining washer around the piston, then compress the spring to free up enough space to insert the half-rings conical. The spring compression can then be released so that the retaining washer can trap the conical half-rings. It is also noted that sometimes only one half-ring is fitted and this defect is only detected late, resulting in high intervention costs. In addition, the surfaces of the impression, the conical half-rings and the housing are machined and fairly precise surfaces, which leads to a high production cost. Statement of the invention It is therefore an objective of the invention to provide a fuel pump for direct fuel injection for internal combustion engines whose construction is reliable and simple and with minimized costs. With these objectives in view, the invention relates to a fuel pump for direct fuel injection for internal combustion engines, the pump comprising a pump body, a pumping chamber in which a piston is slidably mounted, a spring bearing on the one hand on the pump body and on the other hand at one end of the piston projecting from the pump body by means of a retaining washer and connecting means between the retaining washer and the end of the piston, the pump being characterized in that the connecting means comprise a plurality of fingers originating from a ring of the retaining washer and arranged so as to project towards a central axis of the ring, one end of the fingers being housed in a circular groove of the piston and being held by the spring bearing on a shoulder delimiting the circular groove. Thanks to the invention, the fixing of the retaining washer does not require any other part. The risk of a missing part is therefore eliminated. The fact that the connection with the piston is made by fingers, i.e. separate elements, allows for easy assembly in which the retaining washer is inserted onto the piston and the fingers spread apart until they reach the groove. There, the end of the fingers is housed in the groove and locks the retaining washer. This assembly is simple to carry out, it is reliable and the retaining washer can be obtained by cutting and stamping operations, which is inexpensive. According to an advantageous feature, the end of the fingers is flexibly movable relative to the ring. The return of the end of the fingers into the circular groove when the retaining washer is inserted onto the piston occurs spontaneously. According to an improvement, the fingers are inclined relative to a plane perpendicular to the central axis, being oriented to provide a buttress against the piston in the circular groove when the spring presses on the retaining washer. Thus, the more the retaining washer is subjected to an extraction force from the piston, the more the fingertips are pressed into the groove. The fingers distributed all around the groove balance each other. The retention force thus obtained is very high. In particular, the inclination of the fingers is between 15 and 35°, preferably between 20° and 30°. According to a constructive arrangement, a diameter of the bottom of the groove is less than an end diameter of the piston by a value between 2 and 10%, preferably between 4 and 5% of the end diameter. This ensures that the depth of the groove is sufficient to retain the retaining washer, without the piston being excessively weakened. According to other provisions: the retaining washer has a guide ring extending along the central axis of the ring along the spring to center the spring on the retaining washer. Ensure that the spring is centered on the washer of restraint. the retaining washer has an annular-shaped sole connected to the crown to receive the spring. the ring is linked to the crown. the piston has a collar intended to rest against the body of pump and limit the piston stroke when engaging the washer retained on the piston. The piston may already be at the end of the chamber pumping, but sometimes this is too deep to be able to insert the retaining washer on the piston. By providing a collar, we determine in- depending on the stop position of the piston. the pump has a seat receiving the spring and resting on the body of pump, the seat comprising a sleeve on which the spring is centered and surrounding the piston. The invention also relates to a method of mounting a pump as defined above, according to which the piston is introduced into the chamber, the spring is placed around the piston, the retaining washer is placed on the spring, the retaining washer is pressed to compress the spring until the fingers are spread against the piston and the fingers return to the circular groove. This method is simpler than that of the prior art. Brief description of the figures The invention will be better understood and other features and advantages will appear on reading the description which follows, the description making reference to the appended drawings among which: [Fig. 1] is a view of a sectional detail of a pump according to the prior art; [Fig.2] is a similar to [Fig.1] during an assembly phase of a pump according to one embodiment of the invention; [Fig.3] is a view similar to [Fig.2] after mounting the pump; [Fig.4] is a sectional and perspective view of the end of a piston and of a pump retaining washer of [Fig.3]; [Fig.5] is a perspective view of the retaining washer of [Fig.4]; [Fig.6] is a longitudinal sectional view of the retaining washer of the [Fig.5]. Detailed description A fuel pump for direct fuel injection for internal combustion engines according to one embodiment of the invention is shown in Figures 2 to 6. The pump comprises a pump body 5, a pumping chamber 50 in which a piston 1 is slidably mounted, a spring 3 bearing on the one hand on the pump body 5 via a seat 4 and on the other hand at one end 10 of the piston 1 projecting from the pump body 5 via a retaining washer 6. The retaining washer 6 comprises a base 61 of annular shape having a central axis A for receiving the spring 3. The retaining washer 6 further comprises a guide ring 62 also having the central axis A as its axis and extending along the spring 3 from the base 61 to center the spring 3 on the retaining washer 6, and in particular on the base 61. The guide ring 62 has a substantially truncated cone.The crown 62 is extended by a ring 63 also having as its axis the central axis A and extending in a plane raised relative to the plane of the sole 61. Connecting means 7 are provided between the retaining washer 6 and the end 10 of the piston 1. The connecting means 7 comprise a plurality of fingers 70 originating from the ring 63 of the retaining washer 6 and arranged projecting towards the central axis A while being inclined with a base connected to the ring 63 closer to the pump body 5 than the ends 700 of the fingers 70 in contact with the piston 1. The end 700 of the fingers 70 is housed in a circular groove 71 of the piston 1 and is held by the spring 3 bearing on a shoulder 710 delimiting the circular groove 71. The end 700 of the fingers 70 is flexibly movable relative to the ring 63, as will be seen more clearly in connection with the description of the assembly of the pump.In other words, the fingers 70 are inclined relative to a plane perpendicular to the central axis A, being oriented to provide a buttress against the piston 1 in the circular groove 71 when the spring 3 presses on the retaining washer 6. The inclination of the fingers 70 is typically between 24 and 30°. A diameter of the bottom 710 of the circular groove 71 is less than an end diameter of the piston 1 by a value between 4 and 5% of the end diameter. The piston | has a collar 11 intended to come into contact with the pump body 5 and limit the stroke of the piston 1 when the retaining washer 6 is engaged on the piston 1. The collar 11 could be replaced by an elastic ring inserted in a groove. The seat 4 receiving the spring 3 rests on the pump body 5 and is fixed to it. The seat 4 comprises a sleeve 40 on which the spring 3 is centered and surrounding the piston 1. Stop means are housed between the body and the piston 1 so as to limit the stroke of the piston 1 against the spring 3. These stop means are not shown in Figures 2 to 6 and are shown symbolically in [Fig. 1] of the prior art. To assemble the pump, the piston 1 is inserted into the chamber in abutment with the collar 11 on the pump body 5, the seat 4 is fixed on the body around the piston 1, the spring 3 is placed around the piston 1 in abutment with the seat 4, the retaining washer 6 is placed on the spring 3, the retaining washer 6 is pressed to compress the spring 3. The fingers 70 then spread elastically under the action of the end 10 of the piston 1 until they reach the circular groove 71. The elastic return of the fingers 70 pushes the ends of these fingers into the circular groove 71 until they are in abutment with the bottom of the circular groove 71. The spring 3 can then be released, its action is taken up by the retaining washer 6 which comes to bear against the bottom of the circular groove 71 and the shoulder 710.
Claims
Claims
1. Fuel pump for direct injection of fuel for engines internal combustion, the pump comprising a pump body (5), a pumping chamber (50) in which a piston (1) is mounted sliding, a spring (3) bearing on the one hand on the pump body (5) and on the other hand at one end (10) of the piston (1) projecting out of the pump body (5) by means of a retaining washer (6) and connecting means (7) between the retaining washer (6) and the end (10) of the piston (1), the pump being characterized in that the means of connection (7) comprises a plurality of fingers (70) originating from a ring (63) of the retaining washer (6) and arranged projecting towards a central axis (A) of the ring (63), one end (700) of the fingers (70) is housed in a circular groove (71) of the piston (1) and being held by the spring (3) resting on a shoulder (710) delimiting the groove circular (71).
2. A pump according to claim 1, wherein the end (700) of the fingers (70) is flexibly movable relative to the ring (63).
3. A pump according to claim 1 or 2, wherein the fingers (70) are inclined relative to a plane perpendicular to the central axis (A), in being oriented to achieve a buttressing against the piston (1) in the circular groove (71) when the spring (3) presses on the washer of restraint (6).
4. A pump according to claim 3, wherein the inclination of the fingers (70) is between 15 and 35°, preferably between 20° and 30°.
5. Pump according to one of the preceding claims, a diameter of the bottom of the groove is less than an end diameter of the piston (1) of a value between 2 and 10%, preferably between 4 and 5% of the end diameter.
6. Pump according to one of the preceding claims, in which the retaining washer (6) has a guide ring (62) extending along the central axis (A) of the ring (63) along the spring (3) to center the spring (3) on the retaining washer (6).
7. A pump according to claim 6, wherein the retaining washer (6) comprises a sole (61) of annular shape linked to the crown (62) to receive the spring (3).
8. A pump according to claim 6 or 7, wherein the ring (63) is bonded to the crown (62).
9. Pump according to one of the preceding claims, in which the piston (1) has a collar (11) intended to come into contact with the pump body (5) and limit the stroke of the piston (1) during the engagement of the retaining washer (6) on the piston (1).
10. Pump according to one of the preceding claims, characterized in that that it comprises a seat (4) receiving the spring (3) and resting on the pump body (5), the seat (4) comprising a sleeve (40) on in which the spring (3) is centered and surrounding the piston (1).
11. | Method of mounting a pump according to one of the preceding claims preceding, characterized in that the piston (1) is introduced into the chamber, we place the spring (3) around the piston (1), we place the washer of retainer (6) on the spring (3), we press on the retaining washer (6) to compress the spring (3) until the fingers are spread (70) against the piston (1) and the return of the fingers (70) in the circular groove (7).