Integrated Outlet Check Valve and Pressure Relief Valve
The disclosed integrated outlet check valve and pressure relief valve are used in a high pressure fuel pump including a pumping chamber and an outlet fitting defining an outlet passage to a common rail. The pressure relief valve comprises a movable pressure relief valve shuttle including a pressure relief valve surface configured to mate with a pressure relief valve seat in a closed position. The pressure relief valve shuttle moves from the closed position to an open position when pressure in the common rail exerts a force greater than the bias of a pressure relief valve spring. The pressure relief valve shuttle also includes an outlet check valve seat configured to mate with an outlet check valve ball in a closed position. The outlet valve ball moves from the closed position to an open position when pressure in the outlet passage is less than pressure in the pumping chamber.
The present disclosure relates to high pressure fuel supply pumps for gasoline common rail injection systems. More particularly, the present disclosure relates an integrated outlet check valve and a pressure relief valve for use in a high pressure fuel supply pump.
Gasoline Direct Injection (GDI) fuel systems must regulate the fuel volume delivered to the common rail as part of an overall pressure management strategy. Two strategies are currently employed for controlling the quantity of fuel delivered to the pumping chamber and thus the degree to which the common rail is pressurized. One strategy uses a digital on/off solenoid such as disclosed in U.S. Pat. No. 7,707,996 and another uses a proportional valve such as disclosed in U.S. Pat. No. 6,792,916. The solenoid valves used for inlet metering are required to open and close very fast, so the valve actuation is coordinated with the pumping cycles of the high pressure pump. Fast acting solenoid driven valves are known to generate noise from contact between parts such as a valve member and a valve seat, or between a valve member and a valve stop. It is common for inlet metering valves to be arranged at or near the low pressure inlet of a high pressure pump (near the outside of the pump), where the noise generated by valve parts is easily transmitted. It is desirable to reduce the noise associated with inlet metering valves.
Single piston, cam driven high pressure fuel pumps have become a common solution for generating high pressure fuel in common rail direct injection gasoline (GDI) engines. It is known in the industry that the pump must incorporate an outlet check valve to prevent pressure bleed back from the rail while the pump is in the intake stroke cycle. It has become an industry requirement to incorporate a pressure relief valve within the pump to protect the entire high pressure system from an unexpected excess pressure caused by a system malfunction. In order to protect the rail and injectors, the pressure relief valve must be in hydraulic communication with the rail, i.e., in parallel with the pump flow. In order to make the parallel hydraulic communication, typical executions have located the outlet check valve and pressure relief valve as separate devices within the pump housing. It is desirable to incorporate the outlet check valve and pressure relief valves into an outlet connector that can be assembled and tested before attachment to the high pressure pump, as disclosed in U.S. Pat. No. 8,132,558.
The maximum amount of fuel that can be transferred by a fuel pump is a function of the pressure at the end of the pumping cycle, the bulk modulus of the fuel (under that pressure and temperature), the trapped volume of the pump, and leakage losses in the pump. The trapped volume of a high pressure fuel pump is the volume fluidly connected with the pumping chamber, measured when the pumping plunger is at the end of a pumping stroke (TDC). The trapped volume of a high pressure pump commonly includes portions of the inlet check valve, the pump outlet check valve and pressure relief valve exposed to the pumping chamber. The trapped volume of a pump plays a significant role in the overall volumetric efficiency of the pump, especially when the volume displaced by the pumping plunger is small compared to the trapped volume. Keeping the trapped volume as small as possible improves the volumetric efficiency of the high pressure fuel pump. It is common for outlet check valves and pressure relief valves employed in high pressure fuel pumps to include coil springs to bias valve members (such as a valve ball) toward a closed position. It is also common that one or more coil springs employed for this purpose are in a volume exposed to the pumping chamber, which increase the trapped volume of the pump.
Because pressure relief valve flow returns to the pumping chamber, the springs associated with the pressure relief valve, and the chamber containing the springs are in direct communication with the pumping chamber. The volume of fluid in the spring chamber not occupied by the springs contributes to the trapped volume of the pump. The size of the springs necessary to hold the pressure relief valve closed increase along with the operating pressure of the direct injection system. Current and pending emissions regulations require direct injection operating pressures of 350 bar (35 MPa) or above, requiring increased spring dimensions to generate increased spring loads, and can result in increased trapped volume associated with the pressure relief valve.
SUMMARYThe disclosed integrated outlet check valve and pressure relief valve are configured to control pressure and discharge of fuel through a high pressure fuel pump. In the disclosed embodiment, the high pressure fuel pump includes a pumping chamber where a pumping plunger reciprocates between a pumping phase and a charging phase and an outlet fitting defining an outlet passage to a common rail. A benefit of the disclosed integrated outlet check valve and pressure relief valve is the reduction of trapped volume within the high pressure fuel pump.
The pressure relief valve comprises a movable pressure relief valve shuttle which includes a pressure relief valve surface configured to mate with a pressure relief valve seat. In the disclosed embodiment, the pressure relief valve seat is included on a pressure relief valve support and is arranged radially inward of the pressure relief valve surface. The pressure relief valve support defines an outlet flow path where fuel travels to the common rail and also defines sides of the outlet check valve. A pressure relief passage is defined between the pressure relief valve seat and the pressure relief valve surface to allow excess pressure to pass from the common rail. A pressure relief valve cup is arranged concentrically about at least a portion of the pressure relief valve shuttle.
The pressure relief valve is biased toward a closed position by a pressure relief valve spring which comprises a conical disc spring arranged between the pressure relief valve shuttle and the pressure relief valve cup. In the closed position of the pressure relief valve, the pressure relief valve surface mates with the pressure relief valve seat and forms a conical surface together. Mating of the pressure relief valve surface and the pressure relief valve seat prevents fluid communication through the pressure relief passage. The pressure relief valve shuttle moves from the closed position to an open position, wherein the pressure relief valve surface and the pressure relief valve seat are no longer mated, when pressure in the common rail exerts a force greater than the bias of the pressure relief valve spring.
The pressure relief valve shuttle also includes an outlet check valve seat that is configured to mate with an outlet check valve ball. In the disclosed embodiment, the pressure relief valve seat contacts the pressure relief valve shuttle radially outward of the outlet check valve ball.
The outlet check valve ball is biased toward a closed position by an outlet check valve spring. In the closed position, the outlet check valve ball mates with the outlet check valve seat and prevents fluid communication through the outlet flow path. The outlet valve ball moves from the closed position to an open position, permitting fluid communication through the outlet flow path, when pressure in the outlet passage is less than pressure in the pumping chamber.
In this manner, the pressure and discharge of fuel through a high pressure fuel pump is controlled by the integrated outlet check valve and pressure relief valve.
Aspects of a disclosed embodiment will be described in reference to the drawings, where like numerals reflect like elements:
The HPP 10 is illustrated in the form of a single plunger pump driven by a cam 36. A pumping plunger 38 reciprocates in a pump bore 40 to alternately expand the pumping chamber 42 to draw fuel into the pumping chamber and then pressurize the pumping chamber 42 to pump fuel to the common rail 26 via the outlet fitting 18 and rail feed passage 24. A cam follower 44 is biased toward the profile 46 of the cam 36 and is connected to the pumping plunger 38 to translate the shape of the cam profile 46 into reciprocal movement of the pumping plunger 38. The cam 36 has a four-sided profile 46 that will generate four charge/pump cycles of the pumping plunger 38 for each 360° rotation of the cam 36. The cam may have any number of lobes, with most having three or four lobes. The durations of the charging and pumping cycles are a function of the cam profile 46 and rotational speed of the cam 36. The cam 36 in
As shown in
An embodiment of an ICV 12 according to aspects of the disclosure is illustrated in
A control valve solenoid 74 includes a coil that generates a magnetic field in a control valve pole 76 aligned with and adjacent to the inlet valve armature 70. When the control valve solenoid 74 is energized under control of the ECU 28, the magnetic field generated by the solenoid coil attracts the inlet valve armature 70 and the inlet valve 62 is moved to a closed position (shown in
The disclosed ICV configuration reduces the number of impacts between components to two impacts per actuation cycle, specifically impact of the inlet valve 62 and valve seat 58 and impact of the inlet valve 62 and stop pin 68. These impacts occur near the center of the HPP 10, and far from the extremities of the HPP 10 where noise is more easily radiated. Further noise reduction can be attained by selection of the material from which the stop pin 68 is constructed, such that the impact would generate less energetic vibrations. The surface of the valve member 64 that contacts the stop pin may include material such as engineered plastic, for example PEEK, to reduce noise generated by impact of the inlet valve 62 with the stop pin. The stop pin support 60 may be configured to reduce the transmission of impact vibrations from the stop pin to surrounding structures. In the disclosed HPP 10, the end of the stop pin 68 opposite the inlet valve 62 is exposed to a fluid volume leading to the DCV 16 and outlet fitting 18, which may reduce noise radiated from the stop pin 68.
The pumping plunger 38 reciprocates in the pumping bore 40 defined by a plunger sleeve 78. The plunger sleeve 78 is secured to the pump body 48 by a pilot tube 80 received in a shallow bore defined by the pump body 48. The plunger sleeve 78 is biased toward the pump body 48 by a load ring 82 compressed between an internal shoulder 84 of the pilot ring 80 and the lower end of the plunger sleeve 78. A neck portion 86 of the pilot tube 80 supports a plunger seal 88 that seals against a lower portion of the pumping plunger 38. A plunger return spring seat 90 is secured to the lower end of the pumping plunger 38 and a plunger return spring 92 is biased between the plunger return spring seat 90 and an external shoulder 94 of the pilot tube 80. A plunger retaining ring 96 is received in a groove defined at the lower end of the pumping bore 40 to prevent the pumping plunger 38 from being pulled out of the pumping bore 40 by the plunger return spring 92. As shown in
Some leakage will occur between the pumping plunger 38 and pumping bore 40 during pump operation. The disclosed HPP 10 defines a pump drain 98 from the pilot tube 80 to the control valve feed 56 via passages in the control valve seat 58, allowing leakage flow back to the low pressure inlet of the HPP 10. A pumping plunger 38 having a pumping end with a greater diameter than the driven end as shown in
With reference to
Movement of the inlet valve 62 between contact with the stop pin 68 and contact with the valve seat 58 defines the ICV stroke as shown in FIG. 10. According to aspects of the disclosure, the ICV stroke is less than the air gap between the control valve pole 76 and the inlet valve armature 70 when the inlet valve 62 is in the open position, leaving an armature gap between the control valve pole 76 and the inlet valve armature 70 when the inlet valve is in the closed position. The length of the valve stem 66 and the shape of the inlet valve armature 70 are selected to ensure the inlet valve armature 70 does not contact the control valve pole 76 when the inlet valve 62 is in the closed position. As shown in
According to aspects of the disclosure, the PRV spring 118 is a stack of conical disc springs compressed between a pressure relief valve cup (PRV cup) 120 and the PRV shuttle 112 to bias the PRV shuttle 112 toward a closed position illustrated in
The outlet fitting 18 including an integrated PRV 14 and DCV 16 minimize the trapped volume of the HPP 10 to which the outlet fitting 18 is attached, provide high flow capacity through the PRV 14, and the short stroke of the PRV shuttle 112 results in fast actuation and closure of the PRV 14 while the HPP 10 is operating. The DCV ball 106 opens only when the pressure in the high pressure passage 24 leading to the common rail 26 is less than the pressure in the pumping chamber 42 or passage leading from the pumping chamber to the pump outlet fitting 18 as shown in
While the embodiment of the disclosed integrated outlet check valve 16 and pressure relief valve 14 has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit of the disclosure and the scope of the claimed coverage.
Claims
1. An integrated outlet check valve and pressure relief valve for a high pressure fuel pump, said high pressure fuel pump having a pumping chamber where a pumping plunger reciprocates between a pumping phase and a charging phase and an outlet fitting defining an outlet passage to a common rail, said integrated outlet check valve and pressure relief valve comprising:
- a pressure relief valve shuttle movable between a closed position and an open position, said pressure relief valve shuttle having a pressure relief valve surface configured to mate with a pressure relief valve seat and an outlet check valve seat configured to mate with an outlet check valve ball;
- a pressure relief valve cup arranged concentrically about at least a portion of said pressure relief valve shuttle;
- a pressure relief valve spring comprising a conical disc spring arranged between said pressure relief valve shuttle and said pressure relief valve cup, said pressure relief valve spring biasing said pressure relief valve shuttle toward said closed position;
- a pressure relief valve support defining an outlet flow path and including said pressure relief valve seat;
- said outlet check valve ball movable between a closed position and an open position, said outlet check valve ball biased toward said closed position by an outlet check valve spring;
- a pressure relief passage defined between said pressure relief valve seat and said complimentary pressure relief valve surface of said pressure relief valve shuttle; and
- wherein, said outlet check valve ball mates with said outlet check valve seat in said closed position preventing fluid communication through said outlet flow path, said outlet check valve ball moves from said closed position to said open position permitting fluid communication through said outlet flow path when pressure in said outlet passage is less than pressure in said pumping chamber, said pressure relief valve surface mates with said pressure relief valve seat in said closed position preventing fluid communication through said pressure relief passage, and said pressure relief valve shuttle moves from said closed position to said open position permitting fluid communication through said pressure relief passage when pressure in said common rail exerts a force greater than the bias of said pressure relief valve spring.
2. The integrated outlet check valve and pressure relief valve of claim 1, wherein said pressure relief valve cup has an interference fit within said pump outlet fitting and traps said pressure relief valve shuttle, said pressure relief valve spring, said check valve ball, said check valve spring, and said pressure relief valve seat within the pump outlet fitting.
3. The integrated outlet check valve and pressure relief valve of claim 1, wherein said pressure relief valve seat includes an annular, conical surface configured to mate with said pressure relief valve surface.
4. The integrated outlet check valve and pressure relief valve of claim 1, wherein said pressure relief valve surface and said pressure relief valve seat form a conical surface together in said closed position of said pressure relief valve shuttle.
5. The integrated outlet check valve and pressure relief valve of claim 1, wherein said pressure relief valve seat is arranged radially inward of said pressure relive valve surface.
6. The integrated outlet check valve and pressure relief valve of claim 1, wherein said outlet check valve support defines sides of said outlet check valve.
7. The integrated outlet check valve and pressure relief valve of claim 1, wherein said pressure relief valve seat contacts said pressure relief valve shuttle radially outward of said outlet check valve ball.
8. A method of controlling pressure and discharge of fuel through an outlet passage of a high pressure fuel pump, said high pressure fuel pump having a pumping chamber where a pumping plunger reciprocates between a pumping phase and a charging phase, said method comprising:
- providing an outlet check valve ball;
- providing a pressure relief valve support defining an outlet flow path and having a pressure relief valve seat, said pressure relief valve seat having an annular surface;
- providing a pressure relief valve shuttle having a pressure relief valve surface configured to mate with said annular surface of said pressure relief valve seat and an outlet check valve seat configured to mate with said outlet check valve ball, said pressure relief valve surface arranged radially outward of said pressure relief valve seat, said outlet check valve seat arranged radially outward of said outlet check valve ball, said outlet check valve shuttle and said outlet check valve ball exposed to pressure in said outlet passage;
- biasing said pressure relief valve shuttle toward said pressure relief valve seat with a pressure relief valve spring comprising a conical disc spring, said pressure relief valve spring compressing in response to pressure in said outlet passage;
- biasing said outlet check valve ball toward said outlet check valve seat;
- defining a pressure relief passage between said pressure relief valve seat and said pressure relief valve surface;
- moving said pressure relief valve shuttle between a closed position mated with said pressure relief valve surface and preventing fluid communication through said pressure relief passage and an open position permitting fluid communication through said pressure relief passage, said pressure relief valve shuttle moving from said closed position to said open position when pressure in said outlet passage exerts a force greater than the bias of said pressure relief valve spring; and
- moving said outlet check valve ball between a closed position mated with said outlet check valve seat and preventing fluid communication through said outlet flow path and an open position permitting fluid communication through said outlet flow path, said outlet check valve ball moving from said closed position to said open opposition when pressure in said outlet passage is less than pressure in said pumping chamber.
9. The method of claim 8, wherein said step of providing a pressure relief valve cup includes said pressure relief valve cup trapping said pressure relief valve shuttle, said pressure relief valve spring, said check valve ball, said check valve spring, and said pressure relief valve seat within said high pressure fuel pump.
10. The method of claim 8, wherein said step of providing a pressure relief valve seat includes said pressure relief valve seat having an annular, conical surface configured to mate with said pressure relief valve surface.
11. The method of claim 8, wherein said step of providing a pressure relief valve shuttle includes said pressure relief valve surface and said pressure relief valve seat forming a conical surface together in said closed position of said pressure relief valve shuttle.
12. The method of claim 8, further comprising a step of providing an outlet check valve support, said pressure relief valve seat being arranged on said outlet check valve support.
13. The method of claim 8, wherein said step of providing a pressure relief valve shuttle includes said pressure relief valve shuttle contacting said pressure relief valve seat in said closed position radially outward of said check valve ball.
14. The method of claim 8, further comprising a step of calibrating an opening pressure of the pressure relief valve by setting a position of a pressure relief valve cup concentrically about at least a portion of said pressure relief valve shuttle.
Type: Application
Filed: Apr 22, 2019
Publication Date: Jun 11, 2020
Inventors: Richard P. Pellini (South Windsor, CT), Kenneth R. Morel (Bloomfield, CT), David G. Palermo (West Springfield, MA), Dominic M. Myren (Chicopee, MA), Yevgeniy Norkin (Longmeadow, MA), Michael Wegrzyniak (East Granby, CT)
Application Number: 16/390,093