Fuel pump and its assembly method

Abstract

A fuel pump comprises a compression chamber (5) in which the fuel is pressurized, an inlet assembly (13) for supplying the compression chamber (5) with fuel, an outlet assembly (9) for supplying the pressurized fuel from the compression chamber (5), in which the inlet assembly (13) comprises a non-return valve (17) for allowing the passage of fuel from an inlet to the compression chamber (5) and blocking the passage of fuel in the opposite direction. The pump further comprises an outlet housing (6) for receiving the outlet assembly (9) and opening into the compression chamber (5), the outlet housing (6) being in fluid communication via an orifice (8) with the inlet assembly (13) and comprising a shoulder (18) around the orifice (8) and against which the non-return valve (17) is mounted in abutment. Method of mounting a fuel pump Figure for abstract: Fig. 3

Description

Title of the invention: Fuel pump and method of mounting it Technical field

[0001] The present invention relates generally to the injection of fuel into internal combustion engines and more particularly to a fuel pump. It also relates to a method of mounting such a pump. Prior art

[0002] 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 generally electric and powers a high-pressure pump that typically includes a movable pump piston in a pump body. 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 body. The high-pressure fuel is then delivered to injectors that control the injection of fuel directly into the engine's combustion chamber.Such a pump has a non-return valve between the low-pressure circuit and the pumping chamber. The non-return valve allows fuel to enter the pumping chamber and retains it when the piston rises and compresses the fuel.

[0003] Document WO 2023 / 105024 A1 shows such a pump. Figures 1 and 2 reproduce a similar pump. A piston 101 is slidably mounted in a pump body 102 in which a compression chamber 103 is provided. The fuel is supplied to the compression chamber 103 by an inlet assembly which is housed in an inlet housing 104 of substantially cylindrical shape and with an axis perpendicular to the axis of the piston 101. A non-return valve 105 is mounted tightly in the inlet housing 104 and is further retained by a ring 106, which is welded by a weld 106' with the pump body 102 at the outlet of the inlet housing 104. The non-return valve 105 comprises a seat element 107 provided with through holes 108 which cooperates with a flexible shutter 109 located on a first side 110 of the seat element 107.It is further noted that the non-return valve 105 is actuated by means of a needle assembly 111 from a second side 112 of the seat element 107, opposite the first side 110, through a central passage 113 therein. The needle assembly 111 comprises an integral armature 114. of the needle assembly 111, which is attracted by the magnetic field generated by a coil assembly 115 with a pole piece 116, when energized. The needle assembly 111 is biased by a spring 117 toward the seat member 107 and actuates the shutter 109, whereby the check valve is open by default, allowing fuel to enter the compression chamber 103. Energizing the coil assembly 115 retracts the needle assembly 111, generally during a compression phase, allowing the shutter 109 to come into the closed position and seal the holes 108 in the seat member 105. The fuel is then pressurized by the piston 101 and flows toward the outlet 118.

[0004] This pump design has been used successfully on gasoline engines, operating at pressures up to 350 bar. However, it is now desirable to increase the pressure level further, for example to 500 bar and above. This pressure stresses the non-return valve 105 and the forces are taken up by the tight fitting as well as by the weld 106' of the ring 106 on the part 102. In addition, the ring 106 is supported on the part 107 on the face side 112 of the inlet housing 104 so that the non-return valve 105 is in axial abutment only on the left side, supported on the ring 106. It is thus possible for the non-return valve 105 to start moving in the inlet housing 104 (to the right). Statement of the invention

[0005] It is therefore an objective of the invention to propose a fuel pump which is very reliable while being simple to install.

[0006] With this objective in view, the invention relates to a fuel pump comprising a compression chamber in which the fuel is pressurized, an inlet assembly for supplying the compression chamber with fuel, an outlet assembly for supplying the pressurized fuel from the compression chamber, in which the inlet assembly comprises a non-return valve for allowing the passage of fuel from an inlet to the compression chamber and blocking the passage of fuel in the opposite direction, the pump being characterized in that it comprises an outlet housing for receiving the outlet assembly and opening into the compression chamber, the outlet housing being in fluid communication via an orifice with the inlet assembly and comprising a shoulder around the orifice and against which the non-return valve is mounted to bear.

[0007] By placing the non-return valve in the direction as defined above, the valve is mounted on the body by being stopped as close as possible, without an intermediate part and without passing through a weld. Reliability is improved and assembly is simplified in that it eliminates the intermediate part (106 in the pump of [Fig.l]) and a weld of this part. The creation of the outlet housing does not create constraints additional, but simply requires a reorganization of the pump components.

[0008] The present pump is advantageously used to compress fuel, in particular gasoline, towards a rail to which fuel injectors are connected.

[0009] According to a constructive arrangement, the non-return valve comprises a seat element provided with through holes which cooperates with a flexible shutter located on a first side of the seat element placed opposite the shoulder. The seat element constitutes the body of the non-return valve, the through holes allowing the passage of fuel from the inlet to the compression chamber. The flexible shutter makes it possible to automatically close the through holes to oppose the return of fuel from the compression chamber to the inlet. The forces due to the fuel pressure are taken up directly as close as possible by the shutter, the seat element and the shoulder. Such an arrangement makes it possible to achieve pressures greater than 500 bars.

[0010] According to another constructive arrangement, the non-return valve comprises a cage which surmounts the shutter and which is fixed on the first side of the seat element, the cage limiting the bending of the shutter in the direction of opening. It is also possible to use a flexible shutter with great flexibility so that opening occurs easily without opposing great resistance. Despite this great flexibility, the cage makes it possible to limit the travel of the shutter and to prevent it from deforming too much. The cage is for example fixed to the seat element by welding.

[0011] According to an improvement, the inlet assembly comprises an actuator comprising a needle movable between a rest position for controlling the opening of the shutter and a retracted position for authorizing the closing of the shutter, the needle passing through a central passage of the seat element to act on the shutter. This provides a means which makes it possible to maintain the opening of the passage between the compression chamber and the inlet such that, when the needle acts on the shutter, this passage is kept open and prevents the fuel pressure from rising.

[0012] According to a constructive arrangement, the non-return valve is tightly mounted in the outlet housing. It is thus not necessary to provide special fixing means for the non-return valve, the tightening in its housing being sufficient to lock the non-return valve in position. This tightening does not need to be very strong since the majority of the forces come from the fuel pressure and are taken up by the shoulder. This tight fitting assembly also contributes to the peripheral sealing of the non-return valve.

[0013] The invention also relates to a method of mounting a fuel pump as defined above, according to which a pump body is provided comprising a inlet housing, an outlet housing and a compression chamber, the outlet housing being in fluid communication with the compression chamber and the inlet housing via an orifice, the outlet housing having a shoulder around the orifice, a non-return valve is inserted into the outlet housing and the non-return valve is pushed into abutment against the shoulder.

[0014] According to a particular arrangement, a pusher is used comprising studs coming into contact with bare areas of the seat element to push the non-return valve against the shoulder. It is thus possible to exert strong pressure on the seat element while the accessories such as the cage or the shutter are preserved by being arranged between the studs. Brief description of the figures

[0015] 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:

[0016] - [Fig.l] is a sectional view of a pump according to the prior art; - [Fig.2] is a view of detail II of [Fig.l]; - [Fig.3] is a sectional view of a pump according to one embodiment of the invention; - [Fig.4] is a view of detail IV of [Fig.3]; - [Fig.5] is a sectional view of the pump body shown without any component; - [Fig.6] is a sectional view of the pump body shown with the non-return valve approaching; - [Fig.7] is a sectional view of the pump body shown with the non-return valve in its position before force insertion; - [Fig.8] is a perspective view of a pusher used for inserting the non-return valve; - [Fig.9] is a sectional view of the pump body shown with the non-return valve in its final position and with the pusher; - [Fig. 10] is a sectional view of the pump body with the non-return valve in place;

[0017] - [Fig.l 1] is a perspective view of a non-return valve forming part of the pump of [Fig.3]. Detailed description

[0018] A fuel pump according to one embodiment of the invention is shown in Figures 3 to 8, 9 and 10. The pump comprises a pump body 1. A piston 2 is slidably mounted in the pump body 1 and comprises a first end 3 which is intended to be actuated by the cam of a camshaft, not shown. The details of the construction and operation of the piston 2 are not given here, because they correspond in every respect to the prior art. A second end 4 of the piston 2 opposite the first end 3 opens into a compression chamber 5. Perpendicular to the axis of the piston 2 are respectively produced an outlet housing 6 and an inlet housing 7 connected to each other by an orifice 8. Concretely, the compression chamber 5 is a part of the outlet housing 6. The orifice 8 therefore terminates the inlet housing 7 on the side of the compression chamber 5 and the outlet housing 6.

[0019] The outlet housing 6 receives an outlet assembly 9 comprising a non-return module 10 (forming the outlet valve) and then an outlet nipple 11 by screwing into the pump body 1. The inlet housing 7 receives an actuator 12 forming part of an inlet assembly 13 and comprising a movable needle 14 projecting towards the outlet housing 6. The actuator 12 typically comprises a movable armature 12.1 to which the needle 14 is fixed. The armature 12.1 is attracted by the magnetic field generated by a coil assembly 12.2 with a pole piece 12.3, when it is energized, thus moving the needle to the left in the plane of [Fig.3].

[0020] The fuel supply is achieved via a supply chamber 15, to which the fuel is supplied, in communication with the inlet housing 7 by a supply channel 16. The outlet assembly 9 supplies the pressurized fuel from the compression chamber 5 to injectors via pipes, not shown, connected to the outlet nipple 11. For example, the non-return module 10 comprises for this purpose a spherical shutter held under pressure on a seat via a spring. The ball rises from the seat and allows the passage of liquid fuel towards the nipple 11 when the fuel pressure in the chamber exceeds the force of the spring.

[0021] The inlet assembly 13 further comprises a non-return valve 17 to allow the passage of fuel from the inlet housing 7 to the compression chamber 5 and to block the passage of fuel in the opposite direction. The outlet housing 6 comprises a shoulder 18 around the orifice 8 and against which the non-return valve 17 is mounted to bear. The non-return valve 17 comprises a seat element 19 with through holes 20 which cooperates with a flexible shutter 21 located on a first side 191 of the seat element 19 placed opposite the shoulder 18. The non-return valve 17 further comprises a cage 22 which surmounts the shutter 21 and which is fixed on the first side 191 of the seat element 19 (e.g. by welding), the cage 22 limiting the bending of the shutter 21 in the direction of opening, i.e. away from the seat element 19. The non-return valve 17 is press-fitted in the outlet housing 6.For this, as can be seen in [Fig.5], the housing of . outlet 6 has a clamping zone 23 in the immediate vicinity of the shoulder 18. This clamping zone 23 is in practice a diameter of the outlet housing 6 narrower than the upstream part. The tight fitting assembly of the seat element 19 also ensures a peripheral metal / metal seal.

[0022] The needle 14 of the actuator 12 is movable between a rest position to control the opening of the shutter 21 and a retracted position to allow the closing of the shutter 21. In the closed position, the shutter rests on the seat element and covers the holes 20 which are therefore closed. For this, the needle 14 passes through a central passage 24 of the seat element 19 to act on the shutter 21. The needle 14 is returned by a spring 27 towards the seat element 19 and actuates the shutter 21, whereby the non-return valve is open by default.

[0023] To assemble the fuel pump, the non-return valve 17 is inserted into the outlet housing 6 as shown in [Fig. 6] and the non-return valve 17 is pushed up to the clamping zone 23 as shown in [Fig. 7]. A pusher P is then inserted as shown in [Fig. 8] by bringing studs PI of the pusher P into contact with the free zones 25 of the seat element 19 of the non-return valve 17. Using a press, the pusher P is pressed and the non-return valve 17 is brought into abutment against the shoulder 18, as shown in [Fig. 9]. The pusher P is then removed, as shown in [Fig. 10], then the other parts of the pump are put in place, in particular the non-return module 10 then the outlet nipple 11 in the outlet housing 6, and the actuator 12 in the inlet housing 7.

[0024] In operation, the fuel is supplied to the supply chamber 15, then it passes through the supply channel 16 into the inlet housing 7. In an intake phase, the piston 2 slides in the pump body 1 in a direction in which it tends to exit the body 1. This results in a suction of the fuel which then passes through the through holes 20 of the non-return valve 17, which tends to lift the shutter 21 (open by default) and which opens into the compression chamber 5. During a compression phase, the piston 2 follows an opposite movement and tends to compress the fuel in the compression chamber 5. If the actuator 12 is actuated, the needle 14 is retracted and the shutter is in contact with the through holes 20, so that the fuel is prevented from returning to the inlet housing 7. The fuel is then forced towards the non-return module 10 and the outlet nipple 11.If the actuator 12 is not actuated, the needle 14 protrudes and blocks the shutter 21 in the open position. The fuel is then forced back to the inlet housing 7 through the through holes 20. When the fuel is compressed in the compression chamber 5, it exerts a significant force against the shutter 21. The shutter 21 is pressed against the seat element 19 which resists very well. The seat element 19 is pressed against the shoulder 18, which allows these forces to be absorbed as closely as possible.

Claims

Claims

1. Fuel pump comprising a compression chamber (5) in which the fuel is pressurized, an inlet assembly (13) for supplying the compression chamber (5) with fuel, an outlet assembly (9) for supplying the pressurized fuel from the compression chamber (5), in which the inlet assembly (13) comprises a non-return valve (17) for allowing the passage of fuel from an inlet to the compression chamber (5) and blocking the passage of fuel in the opposite direction, the pump being characterized in that it comprises an outlet housing (6) for receiving the outlet assembly (9) and opening into the compression chamber (5), the outlet housing (6) being in fluid communication via an orifice (8) with the inlet assembly (13) and comprising a shoulder (18) around the orifice (8) and against which the non-return valve (17) is mounted to bear.

2. Fuel pump according to claim 1, wherein the non-return valve (17) comprises a seat element (19) provided with through holes (20) which cooperates with a flexible shutter (21) located on a first side (191) of the seat element (19) placed opposite the shoulder (18).

3. The fuel pump of claim 2, wherein the check valve (17) comprises a cage (22) which surmounts the shutter (21) and which is fixed on the first side (191) of the seat member (19), the cage (22) limiting the flexion of the shutter (21) in the direction of opening.

4. Fuel pump according to one of claims 2 or 3, in which the inlet assembly (13) comprises an actuator (12) comprising a needle (14) movable between a rest position to control the opening of the shutter (21) and a retracted position to authorize the closing of the shutter (21), the needle (14) passing through a central passage of the seat element (19) to act on the shutter (21).

5. A fuel pump according to any preceding claim, wherein the non-return valve (17) is press-fitted into the outlet housing (6).

6. Method of mounting a fuel pump according to one of the preceding claims, characterized in that a body is provided pump (1) comprising an inlet housing (7), an outlet housing (6) and a compression chamber (5), the outlet housing (6) being in fluid communication with the compression chamber (5) and the inlet housing (7) via an orifice (8), the outlet housing (6) comprising a shoulder (18) around the orifice (8); a non-return valve (17) is inserted into the outlet housing (6); and the non-return valve (17) is pushed into abutment against the shoulder (18).

7. Mounting method according to claim 6, for a pump according to claim 2, according to which a pusher (P) is used comprising studs (PI) coming into contact with exposed areas (25) of the seat element (19) to push the non-return valve (17) against the shoulder (18).

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