Fuel pump for the direct-injection of fuel for internal combustion engines
Patent Information
- Application Number
- EP2023742300
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-15
- Filing Date
- 2023-07-14
- Publication Date
- 2025-05-21
- Estimated Expiration
- 2043-07-14
AI Technical Summary
The existing fuel pump designs for direct fuel injection in internal combustion engines are complex and costly due to precise machining requirements and potential assembly errors, particularly with the use of conical half-rings and retainers which complicate assembly and increase production costs.
A fuel pump design featuring a retaining washer with a ring of fingers that project towards a central axis, allowing for easy assembly by inserting the washer onto a piston with fingers that spontaneously lock into a circular groove, eliminating the need for additional parts and reducing production costs, with the fingers' inclination providing a high retention force.
The new design simplifies assembly, reduces production costs, and ensures reliable retention without the risk of missing parts, while maintaining the structural integrity of the piston, thus offering a cost-effective and reliable fuel pump solution.
Smart Images
Figure 1.1
Abstract
Description
[0001] Fuel pump for direct fuel injection for internal combustion engines.
[0002] Technical field
[0003] The invention relates to a fuel pump for direct fuel injection for internal combustion engines.
[0004] Prior art
[0005] Fuel systems in modern gasoline-powered internal combustion engines, particularly those for the automotive market, utilize direct gasoline injection in which fuel injectors are used to inject fuel directly into the engine's combustion chambers. In such direct injection systems, fuel from the tank is supplied by a low-pressure fuel pump integrated into the tank. This low-pressure pump is usually electric and powers a high-pressure pump that typically includes a movable pump piston within a pump housing. The pump piston is actuated by a camshaft of the internal combustion engine to raise the fuel pressure in a pump chamber of the pump housing. The high-pressure fuel is then delivered to the injectors, which control the injection of fuel directly into the engine's combustion chamber.
[0006] Document EP 3 715 619 A1 shows an example of a pump of this type. An example is also reproduced in Figure 1. The movement of the piston 101 in the pumping chamber 1050 is provided by the camshaft 102 against a spring 103 which tends to keep one end of the piston 101 resting on a cam of the camshaft 102. The spring is of the helical compression type and bears on the one hand on a seat 104 fixed on the body 105 of the pump and on the other hand on a retaining washer 106 connected to the end of the piston 101 by connecting means 107. The connecting means comprise two conical half-rings 1071 engaged with an imprint 1072 at the end of the piston and a conical housing 1073 carried by the retaining washer 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 conical half-rings 1071 wedged in the housing 1073.
[0007] Although these retaining means are effective, they have some drawbacks. Assembly operations are complex. The spring and retaining washer must be placed around the piston, then the spring must be compressed to create enough space to insert the tapered half-rings. The spring compression can then be released so that the retaining washer can trap the tapered half-rings. It is also noted that sometimes only one half-ring is placed and this defect is only detected late, resulting in high repair costs. In addition, the surfaces of the cavity, the tapered half-rings and the housing are machined and fairly precise surfaces, which results in high production costs.
[0008] Statement of the invention
[0009] 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.
[0010] 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.
[0011] 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.
[0012] According to an advantageous feature, the finger tip is flexibly movable relative to the ring. The return of the finger tip into the circular groove when the retaining washer is inserted onto the piston occurs spontaneously.
[0013] According to an improvement, the fingers are inclined relative to a plane perpendicular to the central axis, being oriented to create an arch 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 end of the fingers is pressed into the groove. The fingers distributed all around the groove balance each other. The retention force thus obtained is very high.
[0014] In particular, the inclination of the fingers is between 15 and 35°, preferably between 20° and 30°.
[0015] 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.
[0016] According to other provisions:
[0017] • 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 properly centered on the retaining washer.
[0018] • the retaining washer has an annular-shaped base connected to the crown to receive the spring. the ring is connected to the crown. • the piston has a collar intended to come into contact with the pump body and limit the stroke of the piston when the retaining washer is engaged on the piston. The piston may already be in abutment at the bottom of the pumping chamber, but sometimes this is too deep to be able to insert the retaining washer on the piston. By providing a collar, the stop position of the piston is determined independently.
[0019] • the pump has a seat receiving the spring and resting on the pump body, the seat comprising a sleeve on which the spring is centered and surrounding the piston.
[0020] 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.
[0021] Brief description of the figures
[0022] 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:
[0023] • Figure 1 is a view of a sectional detail of a pump according to the prior art;
[0024] • figure 2 is a similar to figure 1 during a phase of assembly of a pump according to an embodiment of the invention;
[0025] • Figure 3 is a view similar to Figure 2 after the pump has been mounted;
[0026] • Figure 4 is a sectional and perspective view of the end of a piston and a retaining washer of the pump of Figure 3; Figure 5 is a perspective view of the retaining washer of Figure 6 is a longitudinal sectional view of the retaining washer of Figure 5.
[0027] Detailed description
[0028] 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 an annular-shaped base 61 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 crown 62 has a substantially truncated cone shape.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.
[0029] 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 better 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 form an arch 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.
[0030] 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 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.
[0031] 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. Optionally, stop means (not shown) may be housed between the body and the piston 1 so as to limit the stroke of the piston 1 against the spring 3.
[0032] 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 fuel injection for internal combustion engines, the pump comprising 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) and on the other hand on one end (10) of the piston (1) projecting from 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 connecting means (7) comprise a plurality of fingers (70) originating from a ring (63) of the retaining washer (6) and arranged so as to project towards a central axis (A) of the ring (63), one end (700) of the fingers (70) being housed in a circular groove (71) of the piston (1) and being held by the spring (3) resting on a shoulder (710) delimiting the circular groove (71),the fingers (70) being inclined relative to a plane perpendicular to the central axis (A), being oriented to produce an arching against the piston (1) in the circular groove (71) when the spring (3) presses on the retaining washer (6)., 2. Pump according to claim 1, wherein the end (700) of the fingers (70) is flexibly movable relative to the ring (63).
3. Pump according to claim 1 or 2, wherein the inclination of the fingers (70) is between 15 and 35°, preferably between 20° and 30°.
4. 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) by a value between 2 and 10%, preferably between 4 and 5% of the end diameter.
5. Pump according to one of the preceding claims, in which the retaining washer (6) comprises 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).
6. Pump according to claim 5, in which the retaining washer (6) comprises a sole (61) of annular shape connected to the crown (62) to receive the spring (3). Pump according to claim 5 or 6, in which the ring (63) is connected to the crown (62). Pump according to one of the preceding claims, in which the piston (1) comprises a collar (11) intended to come to bear against the pump body (5) and limit the stroke of the piston (1) when the retaining washer (6) is engaged on the piston (1). Pump according to one of the preceding claims, characterized in that it comprises a seat (4) receiving the spring (3) and bearing on the pump body (5), the seat (4) comprising a sleeve (40) on which the spring (3) is centered and surrounding the piston (1).Method for mounting a pump according to one of the preceding claims, characterized in that the piston (1) is introduced into the chamber, the spring (3) is placed around the piston (1), the retaining washer (6) is placed on the spring (3), the retaining washer (6) is pressed to compress the spring (3) until the fingers (70) are separated against the piston (1) and the fingers (70) return into the circular groove (71).