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CN-122029349-A - Fuel pump with pressure reducing valve

CN122029349ACN 122029349 ACN122029349 ACN 122029349ACN-122029349-A

Abstract

The invention relates to a fuel pump comprising a compression chamber (10) and a pressure relief valve (2), fuel being pressurized in the compression chamber (10), the pressure relief valve (2) having an inlet communicating with a high pressure outlet (13) for releasing fuel, wherein the pressure relief valve (2) is placed in a cavity (15) and comprises a closing member (20) urged by a spring (21) to abut a valve seat (220) carried by a valve seat ring (22). The pressure relief valve (2) comprises a guide (23), against which the spring (21) abuts and is opposite to the closing member (20), wherein the guide (23) is slidably mounted in a stop ring (25) which is fixed in the cavity (15) and which limits the sliding of the guide (23) against the spring (21).

Inventors

  • L. VINCENT

Assignees

  • 菲尼亚德尔福卢森堡有限公司

Dates

Publication Date
20260512
Application Date
20241025
Priority Date
20231113

Claims (12)

  1. 1. A fuel pump comprising a compression chamber (10) in which fuel is pressurized, a high-pressure outlet (13) in communication with the compression chamber (10) via a check valve (12), and a relief valve (2) having an inlet in communication with the high-pressure outlet (13) to release fuel when the pressure exceeds a predetermined threshold, the relief valve (2) being placed in a cavity (15) and comprising a closing member (20) urged by a spring (21) to bear against a valve seat (220) carried by a valve seat ring (22), the pump being characterized in that the relief valve (2) comprises a guide (23), the spring (21) being supported on the guide (23) and opposite the closing member (20), the closing member (20) comprising a stem (204) guided translationally in the guide (23), the guide (23) being slidably mounted in a stop ring (25), the stop ring (25) being fixed in the cavity (15) and comprising the stop ring (25) against the position of the guide (25).
  2. 2. Pump according to claim 1, wherein the adjustment means are realized by a tight fit of the stop ring in the cavity (15).
  3. 3. Pump according to claim 1 or 2, wherein the pressure relief valve (2) comprises stop means (24, 24 ") allowing to hold the guide (23) on the closure member (20) and thus to capture the spring (21).
  4. 4. A pump according to claim 3, wherein the stop means (24) are formed by a circular groove (240) provided in the stem (204) and a resilient ring (241) cooperating with the circular groove (240) to act as a barrier for the sliding of the guide (23) on the stem (204).
  5. 5. A pump according to claim 3, wherein the stop means (24 ") comprise a cylindrical head (244) at the end of the stem (204") which cooperates with a shoulder (242) of the guide (23), the outer diameter of the head (244) being greater than the inner diameter of the shoulder (242), and connection means (26) divide the stem (204 ") into two assembled parts (204 a, 204 b).
  6. 6. Pump according to any of the preceding claims, wherein the stop ring (25) or the guide (23) is adapted to enable fluid communication between the outlet (151) of the cavity (15) and the valve seat (220).
  7. 7. The pump of claim 6, wherein the outlet (151) of the cavity communicates with a supply chamber (16), or leads to the supply chamber (16), the supply chamber (16) being configured to receive fuel supplied to the pump.
  8. 8. Pump according to any of the preceding claims, wherein the closing member (20) comprises a centering stud (202) for centering the spring (21).
  9. 9. Pump according to any of the preceding claims, wherein the guide (23) comprises a centering sleeve (230) for guiding the radial position of the spring (21) when the spring (21) is supported on the guide (23).
  10. 10. The pump according to any one of the preceding claims, wherein the closure member (20) comprises a biasing body (200) carrying a ball (201) that is urged against the valve seat (220).
  11. 11. Pump according to any of the preceding claims, wherein the valve seat ring (22) carrying the valve seat (220) is housed at and tightly fitted with the bottom of the cavity (15).
  12. 12. A method for mounting a pressure reducing valve (2) on a fuel pump according to any one of the preceding claims, characterized in that the method comprises the steps of: -inserting the valve seat ring (22) into the cavity (15); -at the same time, assembling a sub-assembly having the closing member (20), the spring (21) surrounding the stem (204), the guide (23) mounted on the stem (204) and supported on the spring (21); -inserting the sub-assembly into the cavity (15), the closing member (20) being supported on the valve seat ring (22); then in any order: -inserting the stop ring (25) to stop the guide (23) in a position providing a predetermined compression force of the spring (21); The predetermined compression force is controlled by pressing the guide (23) against the spring (21).

Description

Fuel pump with pressure reducing valve Technical Field The present invention relates to a high-pressure fuel pump including a pressure reducing valve. Background Fuel systems in modern petroleum-fueled internal combustion engines, particularly those used in the automotive market, use direct injection of petroleum, with fuel injectors used to inject fuel directly into the combustion chambers of the engine. In such a direct injection system, fuel originating from the fuel tank is supplied by a low-pressure fuel pump integrated into the fuel tank. Typically, the low pressure pump is electric and supplies to a high pressure pump, which typically includes a pump piston movable in a pump body. The pump piston is actuated by a camshaft of the internal combustion engine in order to increase the pressure of the fuel in the pumping chamber of the pump body. The high pressure fuel is then distributed to injectors that control the direct injection of the fuel into the combustion chambers of the engine. Such a pump is known from document WO2023/280929A1, wherein the pump comprises a body integrating a compression chamber connected via a valve assembly to an outlet connection to a fuel rail where an injector is connected. Fuel is compressed in the compression chamber by a piston actuated by a camshaft. A relief valve is placed downstream of the valve assembly to ensure safety of operation by limiting pressure and by enabling fuel to return toward the compression chamber. The relief valve comprises a needle terminating in a conical projection that is held in bearing against a valve seat by a spring acting on the needle. Opening of the valve is achieved when a pressure above a predetermined threshold is prevailing at the side of the needle and acts on the protrusion to separate the protrusion from the valve seat against the spring. Other models of pressure relief valves have also been proposed. Document DE102019200025A1 shows a fuel pump in which a pressure reducing valve is accommodated in a bore of a compression chamber which is radially open. The bore is closed from view by the base and it contains a spring supported on the base, a biasing body slidably mounted in the support, a ball bearing on one end of the biasing body and a ring including a valve seat at its centre against which the balls are pressed by the spring. The ring is forcibly fitted into the hole and its position determines the compression of the spring. The bore opens at the outlet of the pump. Document US11,015,558B2 shows a device that combines a relief valve with a check valve placed on the outlet of a fuel pump. The valve portion comprises a cavity in which a spring is placed, the spring acting on a biasing body carrying balls at its ends. The balls rest against a valve seat carried by a ring press fitted into the cavity. It may be noted that in the latter embodiment, the spring may flex under certain conditions, particularly because the biasing body with the ball is free to pivot on the valve seat. This may lead to reduced operability, in particular to a change in the release pressure or premature wear. Disclosure of Invention The object of the present invention is to provide a fuel pump which is integrated with a reliable, durable pressure relief valve, which is capable of regulating the relief pressure. In accordance with these objects, the present invention is a fuel pump comprising a compression chamber in which fuel is pressurized, a high-pressure outlet communicating with the compression chamber via a check valve, and a relief valve having an inlet communicating with the high-pressure outlet to release the fuel when the pressure exceeds a predetermined threshold, the relief valve being placed in a cavity and comprising a closing member urged by a spring against a valve seat carried by a valve seat ring, the pump being characterized in that the relief valve comprises a guide on which the spring is supported opposite the closing member, the closing member comprising a stem guided translationally in the guide, the guide being slidably mounted in a stop ring, the stop ring being fixed in the cavity and limiting the sliding of the guide against the spring, the relief valve comprising means for adjusting the position of the stop ring. With such a pump, the spring is mounted on two slidable parts, which allows avoiding buckling of the latter. Thus, the risk of wear or pressure change is reduced, thereby improving the reliability of the pump. In addition, since the guide is independent of the stopper ring, it can be pressed against the guide, thereby obtaining the biasing force of the spring. This makes verification of the valve possible. The pressure exerted by the spring can even be calibrated by adjusting the position of the stop means until the restoring force of the spring at the desired level is obtained. According to one embodiment, the adjustment means is formed by a tight fit of the stop ring in the cavity. The adjustment is performed by the e