WO2012075483A2

WO2012075483A2 - Check valve for high-pressure fuel injector

Info

Publication number: WO2012075483A2
Application number: PCT/US2011/063255
Authority: WO
Inventors: Keith Steven Schulz
Original assignee: International Engine Intellectual Property Company, Llc
Priority date: 2010-12-03
Filing date: 2011-12-05
Publication date: 2012-06-07
Also published as: CN103237981A; WO2012075483A3

Abstract

A fuel injector comprises a pressurization section defining a variable-volume pressurization chamber. A nozzle section has a longitudinal bore, a nozzle chamber, an orifice and a nozzle valve. The nozzle valve is slides in the longitudinal bore between a first position that blocks fluid communication between the nozzle chamber and the orifice, and a second position that opens fluid communication between the nozzle chamber and the orifice. A check valve is between the pressurization chamber and the nozzle chamber. The check valve comprises a housing comprising an upper portion, a lower portion and a middle portion. The housing defines a check valve chamber. A valve member in the check valve chamber hydro-pneumatically moves between an open position that allows fluid communication from the pressurization chamber to the nozzle chamber and a closed position that prevents fluid communication from the nozzle chamber to the pressurization chamber.

Description

CHECK VALVE FOR HIGH-PRESSURE FUEL INJECTOR

RELATED APPLICATIONS

This application makes reference to, claims priority to, and claims the benefit of United States Provisional Patent Application Serial No. 61/419,585, which was filed on December 3, 2010 and is entitled "Structural Geometry In A High- pressure Diesel Fuel Injector." The disclosure of the above-identified provisional patent application is hereby incorporated by reference in its entirety.

BACKGROUND

[0001] Hydraulically actuated, electronically controlled, high-pressure unit fuel injection systems are commonly used in diesel engines. In such systems, fluid is supplied at high-pressure through a common rail to each of a series of unit fuel injectors within the cylinder head. Each injector includes an electronically controlled valve, which governs the application of the high-pressure fluid to provide the force to inject fuel into the engine cylinders.

[0002] Each high-pressure fuel injector has an actuating fluid control valve that is electronically controlled to control the timing and amount of the actuating fluid flowing into the injector. The actuating fluid control valve initiates and terminates the injection process. A representative high-pressure fuel injector has a plunger that is displaced within an internal pressurization chamber by fluid from the rail when an electronically controlled valve in the injector opens in response to a signal from the engine controller. The fluid acts via the plunger to amplify the fuel pressure in the pressurization chamber to a magnitude large enough to force a normally closed valve at an outlet of the fuel injector to open. When the latter valve opens, the amplified fuel pressure forces fuel through the outlet and into the combustion chamber. Terminating the control signal to the electronically controlled valve terminates the injection. When that happens, the valve at the fuel injector outlet returns to normally closed condition, and fluid flows from the rail to refill the pressurization chamber, forcing the plunger to retract in the process. [0003] The high-pressure fuel injectors typically include a check valve in the fuel path between an injector pumping element and an injector nozzle element. The check valve is designed to prevent a back flow of fuel into the pumping element once the delivery of fuel is complete. The check valve also prevents combustion gases from entering the pumping element in the event such gasses pass through valve associated with the nozzle element.

SUMMARY

[0004] A high-pressure fuel injector comprises a pressurization section at least partially defining a variable-volume pressurization chamber. A nozzle section has a longitudinal bore, a nozzle chamber, an orifice and a nozzle valve. The nozzle valve is slidably disposed in the longitudinal bore between a first position that blocks fluid communication between the nozzle chamber and the orifice, and a second position that opens fluid communication between the nozzle chamber and the orifice. A check valve is interposed between the pressurization chamber and the nozzle chamber for controlling fluid communication therebetween. The check valve comprises a housing comprising an upper portion, a lower portion and a middle portion interposed between the upper and lower portion. The housing defines a check valve chamber. A valve member positioned in the check valve chamber and being hydro-pneumatically movable between an open position that allows fluid communication from the pressurization chamber to the nozzle chamber and a closed position that prevents fluid communication from the nozzle chamber to the pressurization.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a cross-sectional view of a high-pressure fuel injector.

[0006] FIG. 2 is an enlarged cross-sectional view further illustrating the check valve assembly of fuel injector of FIG. 1.

[0007] FIG. 3 is an exploded perspective view of a check valve assembly from the fuel injector valve of FIG. 1.

[0008] FIG. 4 is a cross-sectional view of the check valve assembly of FIG. 2. DETAILED DESCRIPTION

[0009] Referring to the drawings, a high-pressure fuel injector 10 generally includes a pressurization section 12 and a nozzle section 14. The pressurization section 12 includes an intensifier body 16 having a longitudinal bore 18. A plunger 20 is slidably mounted in the longitudinal bore 18. The pressurization section 12 at least partially defines a variable-volume pressurization chamber 22. In particular, the volume of the longitudinal bore below the plunger 20 defines pressurization chamber 22. This volume changes as the plunger 20 moves up and down in the longitudinal bore 18.

[0010] A coil spring 24 mounted concentrically around the plunger 20 normally biases the plunger 20 upwardly in the longitudinal bore 18. A piston 26 is positioned in the longitudinal bore 18 above the plunger 20. A control valve body 28 mounted on the upper end of the intensifier body 16 secures the piston 26, plunger 20 and spring 24 within the longitudinal bore 18. The control valve body 28 includes a fluid inlet 30 that is connected to an external source of high-pressure fluid such as a high-pressure manifold (not shown). The valve body 28 carries an electronically actuated control valve 32, such as a spool valve, for controlling application of the high-pressure fluid to the piston 26. The control valve 32 is movable, in response to a control signal, between a first (closed) position where fluid flow to the piston 26 is blocked and a second (open) position at which the high-pressure fluid is applied to the piston. When the control valve 32 is closed, the coil spring 24 biases the plunger 20 upwardly in the longitudinal bore 18. When the control valve 32 is opened, high- pressure fluid is applied to the piston 26 causing the plunger 20 to move downwardly in the longitudinal bore 18.

[0011] The nozzle section 14 includes a spring cage 40 and a nozzle body 41.

While the spring cage 40 and nozzle body 41 are shown as separate components, they could also be formed as an integral unit. The spring cage 40 and nozzle body 41 define a longitudinal bore 42 that terminates in a nozzle orifice 44. A nozzle valve 46 is slidably disposed in the longitudinal bore 42 for movement between a first (closed) position that blocks fluid communication between a nozzle chamber 48 and the orifice 44, and a second (open) position that opens fluid communication between the nozzle chamber 48 and the orifice 44. A coil spring 50 is positioned in the spring cage 40 above the nozzle valve 46 for normally biasing the nozzle valve to its first (closed) position.

[0012] A check valve assembly 52 is interposed between the pressurization chamber 22 and the nozzle chamber 48 for controlling fluid communication therebetween. The check valve assembly 52 includes a housing 54 having an upper portion 56, a lower portion 58 and a middle portion 60 interposed between the upper and lower portions. The housing portions 56-60 are secured together by a plurality of dowel pins 61. The housing portions 56-60 are generally disc-shaped and define a check valve chamber 62. The check valve chamber 62 includes an upper wall 64 defined by the housing upper portion 56, a lower wall 66 defined by the housing lower portion 58, and a side wall 68 defined at least in part by the housing middle portion 60 and extending between the upper and lower walls 64, 66. In comparison to prior two-piece designs, the multi-piece construction of the housing 54 facilitates manufacture and reduces stress under increasing injection pressure.

[0013] A valve member 70 positioned in the check valve chamber 62 is hydro- pneumatically movable between a first (open) position that allows fluid communication from the pressurization chamber 22 to the nozzle chamber 48, and a second (closed) position that prevents fluid communication from the nozzle chamber 48 to the pressurization chamber 22. In the illustrated embodiment, the valve member 70 comprises a check plate 72. The check plate 72 is generally disc-shaped and includes an upper face 74, a lower face 76 and a plurality of fluid passages 78 extending between its upper and lower faces 74, 76. In the illustrated embodiment, the fluid passages 78 comprise scallops cut in the outer edge of the check plate. The fluid passages 78 can take numerous other configurations, including, but not limited to the types illustrated in U.S. Patent No. 5,797,427, the disclosure of which is hereby incorporated by reference in its entirety. The check plate 72 may include a bleed hole 77 to allow fluid to slowly pass, e.g., bleed, through the check plate 72 to equalize pressure across the check plate.

[0014] The housing upper portion 56 defines a fluid passage 80 that permits fluid communication between the pressurization chamber 22 and the check valve chamber 62. The fluid passage 80 extends between an upper face 82 of the housing upper portion 56 and the upper wall 64 of the check valve chamber 62. The upper end of the fluid passage 80 opens to and is in fluid communication with pressurization chamber 22.

[0015] The housing lower portion 58 defines a fluid passage 86 that permits fluid communication between the check valve chamber 62 and the nozzle chamber 48. The fluid passage 86 extends between the lower wall 66 of the check valve chamber 62 and the lower face 88 of the housing lower portion 58. The lower end of the fluid passage 86 is fluidly coupled to the nozzle chamber 48 by a fluid passage 90 defined by the spring cage 40 and the nozzle body 41.

[0016] A cone nut 92 threads onto the lower end of the intensifier body 16.

When the fuel injector 10 is installed in an engine (not shown), the cone nut 92 extends from the intensifier body 16, which is at the exterior of the engine, through the engine wall to the combustion chamber (not shown). The cone nut 92 houses the check valve assembly 52 and the nozzle components, e.g., spring cage 40, nozzle body 41, nozzle valve 46 and coil spring 50. When the cone nut 92 is threaded onto the intensifier body 16, the check valve assembly 52 and nozzle components are clamped into place in their stacked relationship between the cone nut 92 and the intensifier body 16.

[0017] The high-pressure fuel injector 10 includes a supply passage 94 that fluidly connects the pressurization chamber 22 with an external fuel source, such as a fuel manifold (now shown). In this regard, the cone nut 92 includes a plurality of fluid ports 96. When the injector 10 is mounted in the engine, the ports 96 align with the fuel manifold. The ports 96 allow fuel to flow into a low-pressure fuel chamber 98 defined by the gap between the cone nut 92, the check valve assembly 52 and the spring cage 40. As can be seen in Figure 1, the check valve assembly 52 is interposed between the low-pressure fuel chamber 98 and the pressurization chamber 22. The check valve assembly 52 includes a fluid passage 100 that extends between low- pressure fuel chamber 98 and the pressurization chamber 22. A second check valve 102 is positioned along the fluid passage. The second check valve 102 includes a valve member 104, in the form of a ball. The valve member 104 is hydro- pneumatically movable between a first (open) position that allows fluid communication from low-pressure fuel chamber 98 to the pressurization chamber 22, and a second (closed) position that prevents fluid communication from the pressurization chamber 22 to the low-pressure fuel chamber 98. The fluid passage can include an edge filter 101 {see Fig. 3, for filtering debris from the fuel flowing through the passage 100. In the illustrated embodiment, the edge filter is formed in an upper face of the housing lower portion 58. The edge filter could, alternatively, be formed in the lower face of the housing middle portion 60, or in a combination of the opposing faces of the housing middle and lower portions 58, 60.

[0018] Operation of the fuel injector 10 is controlled response to control signals from a controller (not shown), such as an engine controller. Specifically, the controller delivers signals that control operation of the control valve 32 to regulate the timing and amount of actuating fluid flowing to the fuel injector 10. The control valve 32 initiates and terminates the injection process. When the control valve 32 is open, fluid flows through the valve and is applied to the piston 26 to displace the plunger 20 downwardly in the pressurization chamber 22.

[0019] As the plunger 20 descends, fuel is discharged from the pressurization chamber 22 through the passage 80 and into the check valve chamber 62. Gravity and/or the downward force of the high-pressure fluid bias the second valve member 104 to its seated position to prevent fluid flow from the pressurization chamber 22 and the low-pressure fuel chamber 98. The high-pressure fuel flowing through the passage 80 impinges on the upper face 74 of the check plate 72, causing check plate 72 to unseat from the upper wall 64 of the check valve chamber 62. The opening load provided by injection pressure acting on the upper face 74 of the check plate 72 overcomes residual pressure acting on the lower face 76 of the plate 72 to hold the plate 72 up against the upper wall 64. Once this seal is broken, high-pressure fuel passing through the fuel delivery opening passage 80 moves the check plate 72 downward until the plate 72 is seated against a ledge in the check valve chamber 62 in a valve open position. With the check plate 72 in its open position, fuel passes down through passage 80, over the upper face 74 of the check plate 72 to the fluid passages 78, through the fluid passages 78 and out through the fluid passage 86 in the housing lower portion 60.

[0020] The fuel then flows through the delivery passage 90 in the spring cage

40 and nozzle body 41 and into the nozzle chamber 48. The fuel pressure in the chamber 48 acts against the nozzle valve 46 and forces the nozzle valve upwardly against the force of the coil spring 50. Usually, the first pressure wave is sufficient to unseat the nozzle valve 46 and begin fuel injection. If the pressure wave is insufficient to lift the nozzle valve 46, the pressure build-up that immediately follows will do so. When the nozzle valve 46 unseats from the orifice 44, fuel passes through the orifice and is delivered to the associated engine combustion chamber.

[0021] Terminating the control signal to the control valve 32 terminates injection. When that happens, the coil spring 24 retracts the plunger 20 upwardly in the pressurization chamber 22 and the pressure in the chamber 22 decreases rapidly. As these events occur, pressure in the nozzle chamber 48 also drops rapidly and the nozzle valve 46 closes. Fuel injection ends when pressure in the nozzle chamber 48 drops to the closing pressure of the nozzle valve 48, e.g., as set by the coil spring 50. Residual pressure in the check valve chamber 62 holds the check plate 72 upward against the upper wall 64 of the chamber 62 to prevent reverse flow of fuel into the pressurization chamber 22 and maintaining a barrier against the intrusion of cylinder combustion gases into the injector passages 80 and the pressurization chamber 22.

[0022] Additionally, as the plunger 20 retracts, fuel is drawn into the chamber through the inlet passage 100. The valve member 104 unseats to allow fuel to flow from the low-pressure fuel chamber 98 and into the pressurization chamber 22.

Claims

1. A high-pressure fuel injector, comprising: a pressurization section at least partially defining a variable-volume pressurization chamber; a nozzle section having a longitudinal bore, a nozzle chamber, an orifice, and a nozzle valve, the nozzle valve being slidably disposed in the longitudinal bore between a first position that blocks fluid communication between the nozzle chamber and the orifice and a second position that opens fluid communication between the nozzle chamber and the orifice; a check valve interposed between the pressurization chamber and the nozzle chamber for controlling fluid communication therebetween, the check valve comprising: a housing comprising an upper portion, a lower portion and a middle portion interposed between the upper and lower portions, the housing defining a check valve chamber; and a valve member positioned in the check valve chamber and being hydro-pneumatically movable between an open position that allows fluid communication from the pressurization chamber to the nozzle chamber and a closed position that prevents fluid communication from the nozzle chamber to the pressurization.

2. The high-pressure fuel injector of claim 1, wherein the valve member comprises a check plate.

3. The high-pressure fuel injector of claim 2, wherein the check plate is generally disc shaped and includes an upper face, a lower face and a plurality of fluid passages extending between its upper and lower faces.

4. The high-pressure fuel injector of claim 1, wherein the check valve chamber includes an upper wall defined by the housing upper portion, a lower wall defined by the housing lower portion and a side wall extending between the upper and lower walls and being defined at least in part by the housing middle portion.

5. The high-pressure fuel injector of claim 4, wherein the housing upper portion defines a fluid passage that permits fluid communication between the pressurization chamber and the housing chamber, and wherein the housing lower portion defines a fluid passage that permits fluid communication between the housing chamber and the nozzle chamber.

6. The high-pressure fuel injector of claim 1, further comprising a fuel supply passage that fluidly connects the pressurization chamber with a fuel source; and wherein the check valve is interposed along the supply passage and includes a second valve member hydro-pneumatically movable between an open position that allows fluid communication from fuel source to the pressurization chamber and a second position that prevents fluid communication from the pressurization chamber to the fuel source.

7. The high-pressure fuel injector of claim 1, wherein the housing portions are generally disc-shaped.

7. A high-pressure fuel injector, comprising: a pressurization section at least partially defining a variable-volume pressurization chamber; a nozzle section having a longitudinal bore, a nozzle chamber, an orifice, and a nozzle valve, the nozzle valve being slidably disposed in the longitudinal bore between a first position that blocks fluid communication between the nozzle chamber and the orifice and a second position that opens fluid communication between the nozzle chamber and the orifice; and a check valve interposed between the pressurization chamber and the nozzle chamber for controlling fluid communication therebetween, the check valve comprising: a housing comprising an upper portion, a lower portion and a middle portion interposed between the upper and lower portions, the housing portions defining a check valve chamber having an upper wall, a lower wall and a sidewall extending therebetween, the upper portion defining an inlet passage that fluidly couples the pressurization chamber to the check valve chamber through an opening in the upper wall, the lower portion defining an outlet passage that fluidly couples the check valve chamber to the nozzle chamber through an opening in the lower wall; and a check plate movable within the check valve chamber between the upper and lower walls and having opposite upper and lower faces that are alternately seatable against the upper and lower walls of the check valve chamber, respectively; wherein fluid communication from the pressurization chamber to the nozzle chamber can occur when the check plate is seated against the lower wall of the check valve chamber; and wherein fluid communication from the nozzle chamber to the pressurization chamber is blocked when the check plate is seated against the upper wall of the check valve chamber.

8. The high-pressure fuel injector of claim 7, wherein the check plate is generally disc shaped and includes a plurality of fluid passages extending between its upper and lower faces.

9. The high-pressure fuel injector of claim 7, wherein the upper wall of the check valve chamber is defined by the housing upper portion, the lower wall of the check valve chamber is defined by the housing lower portion and the side wall of the check valve chamber is defined at least in part by the housing middle portion.

10. The high-pressure fuel injector of claim 7, further comprising a fuel supply passage that fluidly connects the pressurization chamber with a fuel source; and wherein the check valve is interposed along the supply passage and includes a second valve member hydro-pneumatically movable between an open position that allows fluid communication from fuel source to the pressurization chamber and a second position that prevents fluid communication from the pressurization chamber to the fuel source.