Patent Application
20200263646
The present invention relates to a combination outlet valve and pressure relief valve and a fuel pump using the combination outlet valve and pressure relief valve which supplies fuel to an internal combustion engine.
Fuel systems in modern internal combustion engines fueled by gasoline, particularly for use in the automotive market, employ gasoline direct injection (GDi) where fuel injectors are provided which inject fuel directly into combustion chambers of the internal combustion engine. In such systems employing GDi, fuel from a fuel tank is supplied under relatively low pressure by a low-pressure fuel pump which is typically an electric fuel pump located within the fuel tank. The low-pressure fuel pump supplies the fuel to a high-pressure fuel pump which typically includes a pumping plunger which is reciprocated by a camshaft of the internal combustion engine. Reciprocation of the pumping plunger further pressurizes the fuel in a pumping chamber of the high-pressure fuel pump in order to be supplied to fuel injectors which inject the fuel directly into the combustion chambers of the internal combustion engine. An outlet valve is typically included in an outlet passage of the high-pressure fuel pump where the outlet valve prevents flow of fuel back into the pumping chamber during an intake stroke of the pumping plunger. Additionally, a pressure relief valve is known to be provided to allow fuel to flow back into pumping chamber if the pressure downstream of the high-pressure fuel pump exceeds a predetermined level which may result in unsafe operating conditions. In some known arrangements, such as in U.S. Pat. No. 9,828,958 to Saito and in U.S. Pat. No. 9,644,585 to Lucas, the outlet valve and pressure relief valve are combined into a single component. However, in such known arrangements, springs which bias an outlet valve member and which bias a pressure relief valve member are grounded by separate members which may lead to complexity and cost in manufacturing and the need for specialized seats for the outlet valve and for the pressure relief valve which adds to cost.
What is needed is a fuel pump and a combination outlet valve and pressure relief valve which minimize or eliminate one or more of the shortcomings as set forth above and provide an alternative for fuel systems.
Briefly described, a combination outlet valve and pressure relief valve is provided by the present invention for controlling outlet fuel flow of a fuel pump and for relieving over-pressurization downstream of the fuel pump. The combination outlet valve and pressure relief includes an outer housing having an outer housing passage extending therethrough from an outer housing inlet to an outer housing outlet; an inner housing located within the outer housing passage and extending along an inner housing axis from an inner housing first end face to an inner housing second end face, the inner housing having an outlet valve bore extending thereinto from the inner housing first end face and also having a pressure relief valve bore extending thereinto from the inner housing second end face such that the outlet valve bore and the pressure relief valve bore terminate at an inner housing wall which is traverse to the inner housing axis; an outlet valve assembly located within the outlet valve bore and comprising an outlet valve member, an outlet valve seat, and an outlet valve spring, the outlet valve member being moveable between 1) a seated position which prevents fluid communication between the outer housing inlet and the outer housing outlet through the outlet valve seat and 2) an unseated position which permits fluid communication between the outer housing inlet and the outer housing outlet through the outlet valve seat, the outlet valve spring being grounded to the inner housing wall and biasing the outlet valve member toward the seated position; and a pressure relief valve assembly located within the pressure relief valve bore and comprising a pressure relief valve member, a pressure relief valve seat, and a pressure relief valve spring, the pressure relief valve member being moveable between 1) a seated position which prevents fluid communication between the outer housing outlet and the outer housing inlet through the pressure relief valve seat and 2) an unseated position which permits fluid communication between the outer housing outlet and the outer housing inlet through the pressure relief valve seat, the pressure relief valve spring being grounded to the inner housing wall and biasing the pressure relief valve member toward the seated position. A fuel pump which includes the aforementioned combination outlet valve and pressure relief valve is also provided by the present invention. The combination outlet valve and pressure relief valve and fuel pump including the combination outlet valve and pressure relief valve of the present invention provides for simplified construction.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of the preferred embodiment of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.
This invention will be further described with reference to the accompanying drawings in which:
In accordance with a preferred embodiment of this invention and referring initially to
As shown, low-pressure fuel pump 18 may be provided within fuel tank 14, however low-pressure fuel pump 18 may alternatively be provided outside of fuel tank 14. Low-pressure fuel pump 18 may be an electric fuel pump as are well known to a practitioner of ordinary skill in the art. A low-pressure fuel supply passage 22 provides fluid communication from low-pressure fuel pump 18 to high-pressure fuel pump 20. A fuel pressure regulator 24 may be provided such that fuel pressure regulator 24 maintains a substantially uniform pressure within low-pressure fuel supply passage 22 by returning a portion of the fuel supplied by low-pressure fuel pump 18 to fuel tank 14 through a fuel return passage 26. While fuel pressure regulator 24 has been illustrated in low-pressure fuel supply passage 22 outside of fuel tank 14, it should be understood that fuel pressure regulator 24 may be located within fuel tank 14 and may be integrated with low-pressure fuel pump 18.
Now with additional reference to
Inlet valve assembly 40 will now be described with particular reference to
Valve body 50 is centered about, and extends along, a valve body axis 56 such that valve body 50 extends from a valve body first end 50a to a valve body second end 50b. A valve body bore 58 extends into valve body 50 from valve body first end 50a and terminates at a valve body end wall 60 which extends to valve body second end 50b such that valve body bore 58 is preferably cylindrical. A valve body first inlet passage 62 extends through valve body 50 such that valve body first inlet passage 62 extends from a valve body outer periphery 50c of valve body 50 and opens into valve body bore 58. A valve body second inlet passage 64 (not visible in
A valve body central passage 66 extends through valve body end wall 60 such that valve body central passage 66 connects valve body second end 50b with valve body bore 58 and such that valve body central passage 66 is centered about, and extends along, valve body axis 56. A plurality of valve body outlet passages 68 is provided in valve body end wall 60 such that each valve body outlet passage 68 extends through valve body end wall 60 and such that each valve body outlet passage 68 connects valve body second end 50b with valve body bore 58. Each valve body outlet passage 68 is laterally offset from valve body central passage 66 and extends through valve body end wall 60 in a direction parallel to valve body axis 56.
As shown in the figures, valve body outer periphery 50c may include three sections of distinct diameters. A valve body outer periphery first portion 50d of valve body outer periphery 50c begins at valve body first end 50a and extends to a valve body outer periphery second portion 50e of valve body outer periphery 50c such that valve body outer periphery first portion 50d is smaller in diameter than valve body outer periphery second portion 50e. As shown in the figures, valve body outer periphery first portion 50d may be located entirely outside of pump housing inlet passage 41 and valve body outer periphery second portion 50e includes valve body first inlet passage 62 and valve body second inlet passage 64 such that valve body first inlet passage 62 and valve body second inlet passage 64 are each in constant fluid communication with the portion of pump housing inlet passage 41 that is upstream of inlet valve assembly 40, i.e. valve body first inlet passage 62 and valve body second inlet passage 64 are each in constant fluid communication with the portion of pump housing inlet passage 41 that is between inlet valve assembly 40 and low-pressure fuel pump 18. A valve body outer periphery third portion 50f of valve body outer periphery 50c extends from valve body outer periphery second portion 50e to valve body second end 50b such that valve body outer periphery third portion 50f is larger in diameter than valve body outer periphery second portion 50e. Valve body outer periphery third portion 50f is sealingly engaged with pump housing inlet passage 41 such that fluid communication through pump housing inlet passage 41 past inlet valve assembly 40 at the interface of pump housing inlet passage 41 and valve body outer periphery third portion 50f is prevented and fluid communication through pump housing inlet passage 41 past inlet valve assembly 40 is only possible through valve body bore 58.
Valve spool 52 is made of a magnetic material and is centered about, and extends along, valve body axis 56 from a valve spool first end 52a to a valve spool second end 52b. Valve spool 52 includes a valve spool first portion 52c which is proximal to valve spool first end 52a and a valve spool second portion 52d which is proximal to valve spool second end 52b. Valve spool first portion 52c has a valve spool outer periphery 52e which is complementary with valve body bore 58 such that valve spool outer periphery 52e and valve body bore 58 are sized in order to substantially prevent fuel from passing between the interface of valve spool outer periphery 52e and valve body bore 58. As used herein, substantially preventing fuel from passing between the interface of valve spool outer periphery 52e and valve body bore 58 encompasses permitting small amounts of fuel passing between the interface which still allows operation of high-pressure fuel pump 20 as will readily be recognized by a practitioner of ordinary skill in the art. Valve spool second portion 52d includes a base portion 52f which extends from valve spool first portion 52c such that base portion 52f is smaller in diameter than valve spool first portion 52c, thereby providing an annular space radially between base portion 52f and valve body bore 58. Valve spool second portion 52d also include a tip portion 52g which extend from base portion 52f and terminates at valve spool second end 52b. Tip portion 52g is smaller in diameter than base portion 52f, thereby defining a valve spool shoulder 52h where tip portion 52g meets base portion 52f. Tip portion 52g is sized to be located within valve body central passage 66 of valve body 50 such that tip portion 52g is able to slide freely within valve body central passage 66 in the direction of valve body axis 56. In use, tip portion 52g is used to interface with check valve 54 as will be described in greater detail later.
Valve spool first portion 52c is provided with a valve spool groove 70 which extends radially inward from valve spool outer periphery 52e such that valve spool groove 70 is annular in shape. Valve spool groove 70 is selectively aligned or not aligned with valve body first inlet passage 62 and valve body second inlet passage 64 in order to control fluid communication through pump housing inlet passage 41 as will be described in greater detail later. One or more valve spool passages 72 is provided which extend from valve spool groove 70 through valve spool first portion 52c toward valve spool second end 52b, thereby providing fluid communication between valve spool groove 70 and valve body outlet passages 68.
A valve spool end bore 74 extends into valve spool 52 from valve spool first end 52a. As shown, valve spool end bore 74 may include a valve spool end bore first portion 74a which is an internal frustoconical shape and a valve spool end bore second portion 74b which is cylindrical and terminates with a valve spool end bore bottom 74c. A valve spool connecting passage 76 provides fluid communication between valve spool groove 70 and valve spool end bore 74 such that, as shown in the figures, valve spool connecting passage 76 may be formed, by way of non-limiting example only, by a pair of perpendicular drillings.
Check valve 54 includes a check valve member 78 and a travel limiter 80. Check valve 54 is arranged at valve spool second end 52b such that check valve member 78 is moved between a seated position which blocks valve body outlet passages 68 (shown in
Solenoid assembly 55 includes a solenoid inner housing 82, a pole piece 84 located within solenoid inner housing 82, a return spring 86, a spool 88, a coil 90, an overmold 92, and a solenoid outer housing 94. The various elements of solenoid assembly 55 will be described in greater detail in the paragraphs that follow.
Solenoid inner housing 82 is hollow and is stepped both internally and externally such that an inner housing first portion 82a is open and larger in diameter than an inner housing second portion 82b which is closed. Solenoid inner housing 82 is centered about, and extends along valve body axis 56. The outer periphery of inner housing first portion 82a sealingly engages fuel pump housing 28 in order to prevent leakage of fuel from pump housing inlet passage 41 to the exterior of high-pressure fuel pump 20 and an annular gap is provided between the inner periphery of inner housing first portion 82a and valve body outer periphery second portion 50e in order to provide fluid communication between pump housing inlet passage 41 and valve body second inlet passage 64. The inner periphery of inner housing second portion 82b mates with valve body outer periphery first portion 50d to prevent communication of fuel between the interface of the inner periphery of inner housing second portion 82b and valve body outer periphery first portion 50d.
Pole piece 84 is made of a magnetically permeable material and is received within inner housing second portion 82b such that pole piece 84 is centered about, and extends along, valve body axis 56. A pole piece first end 84a is frustoconical such that the angle of pole piece first end 84a is complementary to the angle of valve spool end bore first portion 74a. In this way, pole piece first end 84a is received within valve spool end bore first portion 74a. A pole piece second end 84b, which is opposed to pole piece first end 84a, is located at the closed end of solenoid inner housing 82. A pole piece bore 84c extends axially through pole piece 84 from pole piece first end 84a to pole piece second end 84b such that the larger diameter portion of pole piece bore 84c extends into pole piece 84 from pole piece first end 84a, thereby defining a pole piece shoulder 84d which faces toward valve spool bore bottom 74c. Return spring 86 is received partially with pole piece bore 84c such that return spring 86 abuts pole piece shoulder 84d. Return spring 86 is also partially received within valve spool end bore second portion 74b and abuts valve spool end bore bottom 74c. Return spring 86 is held in compression between pole piece shoulder 84d and valve spool end bore bottom 74c, and in this way, return spring 86 biases valve spool 52 away from pole piece 84.
Spool 88 is made of an electrically insulative material, for example plastic, and is centered about, and extends along, valve body axis 56 such that spool 88 circumferentially surrounds inner housing second portion 82b in a close-fitting relationship. Coil 90 is a winding of electrically conductive wire which is wound about the outer periphery of spool 88 such that coil 90 circumferentially surrounds pole piece 84. Consequently, when coil 90 is energized with an electric current, valve spool 52 is magnetically attracted to, and moved toward, pole piece 84 and when coil 90 is not energized with an electric current, valve spool 52 is moved away from pole piece 84 by return spring 86. A more detailed description of operation will be provided later.
Solenoid outer housing 94 circumferentially surrounds solenoid inner housing 82, spool 88, and coil 90 such that spool 88 and coil 90 are located radially between solenoid inner housing 82 and solenoid outer housing 94. Overmold 92 is an electrically insulative material, for example plastic, which fills the void between spool 88/coil 90 and solenoid outer housing 94 such that overmold 92 extends axially from solenoid outer housing 94 to define an electrical connector 96 which includes terminals (not shown) that are connected to opposite ends of coil 90. Electrical connector 96 is configured to mate with a complementary electrical connector (not show) for supplying electric current to coil 90 in use. As shown, a coil washer 98 may be provided within solenoid outer housing 94 axially between coil 90 and overmold 92 in order to complete the magnetic circuit of solenoid assembly 55.
Operation of high-pressure fuel pump 20, and in particular, inlet valve assembly 40, will now be described with particular reference to
Now with particular reference to
Now with particular reference to
Now with particular reference to
As should now be clear, different duty cycles can be provided to vary the amount of fuel metered to pumping chamber 38 where the different duty cycles result in varying magnitudes of alignment of valve spool groove 70 with valve body second inlet passage 64, thereby varying the magnitude of restriction. In other words, the third and fourth positions as described above are only examples of positions of valve spool 52, and other duty cycles can be provided in order to provide different metered amounts of fuel to pumping chamber 38 in order to achieve different output torques of internal combustion engine 12. An electronic control unit 100 may be used to supply electric current to coil 90 at the various duty cycles described herein. Electronic control unit 100 may receive input from a pressure sensor 102 which senses the pressure within fuel rail 44 in order to provide a proper duty cycle to coil 90 in order to maintain a desired pressure in fuel rail 44 which may vary based on the commanded torque desired to be produced by internal combustion engine 12.
Combination outlet valve and pressure relief valve 42 will now be described with particular reference to
Inner housing 104 extends along an inner housing axis 112 from an inner housing first end face 104a to an inner housing second end face 104b. An outlet valve bore 114 extends into inner housing 104 from inner housing first end face 104a while a pressure relief valve bore 116 extends into inner housing 104 from inner housing second end face 104b. Outlet valve bore 114 and pressure relief valve bore 116 are each terminated by an inner housing wall 104c which is travers to inner housing axis 112 and preferably fluidly isolates outlet valve bore 114 from pressure relief valve bore 116 internal to inner housing 104 as illustrated in the figures. Inner housing wall 104c is preferably integrally formed as a single piece with inner housing 104. Outlet valve bore 114 may be stepped as shown, thereby defining an outlet valve spring pocket 114a which is smaller in diameter than the remainder of outlet valve bore 114 such that outlet valve spring pocket 114a extends into inner housing wall 104c. A projection 116a may extend within pressure relief valve bore 116 from inner housing wall 104c such that projection 116a is centered about, and extends along, inner housing axis 112, thereby forming a pressure relief spring pocket 116b which is annular in shape. Projection 116a is preferably integrally formed as a single piece with inner housing 104. Inner housing 104 includes an inner housing outer periphery 104d which surrounds inner housing axis 112 and is cylindrical in shape. Extending into inner housing outer periphery 104d is one or more channels 104e which extend from inner housing second end face 104b toward inner housing first end face 104a, however, channels 104e do not extend all the way to inner housing first end face 104a. An outlet aperture 104f extends radially through inner housing 104 from outlet valve bore 114 to channels 104e. Channels 104e and outlet aperture 104f together define an outlet passage, the function of which will be described in greater detail later. Extending into inner housing outer periphery 104d is a flat 104g which extends from inner housing first end face 104a toward inner housing second end face 104b, however, flat 104g does not extend all the way to inner housing second end face 104b. A pressure relief aperture 104h extends radially through inner housing 104 from pressure relief valve bore 116 to flat 104g. Flat 104g and pressure relief aperture 104h together define a pressure relief passage, the function of which will be described in greater detail later.
Outer housing 110 extends along inner housing axis 112 from an outer housing first end face 110a, which is proximal to pumping chamber 38, to an outer housing second end face 110b, which is distal from pumping chamber 38. An outer housing passage 110c extends therethrough from an outer housing inlet 110d to an outer housing outlet 110e such that outer housing inlet 110d opens into outer housing first end face 110a and such that outer housing outlet 110e opens into outer housing second end face 110b. Outer housing passage 110c is centered about inner housing axis 112 and is cylindrical in shape, preferably sized to engage inner housing outer periphery 104d in an interference fit relationship, thereby preventing fuel from passing between the mating surfaces, i.e. inner housing outer periphery 104d and outer housing passage 110c. Inner housing 104 is located within outer housing passage 110c such that channels 104e and outlet aperture 104f of inner housing 104 are located within outer housing passage 110c, thereby defining an outlet passage located radially between inner housing 104 and outer housing 110. Similarly, flat 104g and pressure relief aperture 104h of inner housing 104 are located within outer housing passage 110c, thereby defining a pressure relief passage located radially between inner housing 104 and outer housing 110. Outer housing 110 includes an outer housing outer periphery 110f which surrounds, and is preferably cylindrical and centered about, inner housing axis 112. As is best seen in
Outlet valve assembly 106 includes an outlet valve seat 118, an outlet valve member 120, and an outlet valve spring 122. Outlet valve seat 118 is located within outlet valve bore 114 of inner housing 104 and includes an outlet valve seat bore 118a extending therethrough such that outlet valve seat bore 118a is centered about, and extends along, inner housing axis 112. Outlet valve seat bore 118a is stepped, thereby defining an outlet valve seating surface 118b which faces toward inner housing wall 104c. A portion of the outer periphery of outlet valve seat 118 proximal to inner housing first end face 104a is sealed to outlet valve bore 114, by way of non-limiting example, by interference fit. One or more outlet valve seat passages 118c extend radially through outlet valve seat 118 from outlet valve seat bore 118a to the outer periphery of outlet valve seat 118 at a location that is downstream of outlet valve seating surface 118b such that outlet valve seat passages 118c are in fluid communication with outlet aperture 104f and channels 104e.
Outlet valve member 120, illustrated herein as a ball by way of non-limiting example only, is moveable between 1) a seated position which prevents fluid communication between outer housing inlet 110d and outer housing outlet 110e via outlet valve assembly 106 and 2) an unseated position which permits fluid communication between outer housing inlet 110d and outer housing outlet 110e via outlet valve assembly 106. One end of outlet valve spring 122 is located within outlet valve spring pocket 114a and is grounded to inner housing wall 104c while the other end of outlet valve spring 122 engages outlet valve member 120, thereby biasing outlet valve member 120 toward the seated position which is in a direction away from pressure relief valve assembly 108. It should be noted that
Pressure relief valve assembly 108 includes a pressure relief valve seat 128, a pressure relief valve member 130, and a pressure relief valve spring 132. Pressure relief valve seat 128 is located within pressure relief valve bore 116 of inner housing 104 and includes a pressure relief valve seat bore 128a extending therethrough such that pressure relief valve seat bore 128a is centered about, and extends along, inner housing axis 112. Pressure relief valve seat bore 128a defines a pressure relief valve seating surface 128b which faces toward inner housing wall 104c. The outer periphery of pressure relief valve seat 128 is sealed to pressure relief valve bore 116, by way of non-limiting example, by interference fit.
Pressure relief valve member 130, illustrated herein as a ball and ball holder by way of non-limiting example only, is moveable between 1) a seated position which prevents fluid communication between outer housing inlet 110d and outer housing outlet 110e via pressure relief valve assembly 108 and 2) an unseated position which permits fluid communication between outer housing inlet 110d and outer housing outlet 110e via pressure relief valve assembly 108. One end of pressure relief valve spring 132 is located within pressure relief spring pocket 116b and is grounded to inner housing wall 104c while the other end of pressure relief valve spring 132 engages pressure relief valve member 130, thereby biasing pressure relief valve member 130 toward the seated position which is in a direction away from outlet valve assembly 106. Pressure relief valve spring 132 is selected to have a desired spring rate, and pressure relief valve seat 128 is inserted sufficiently far into pressure relief valve bore 116, to achieve a desired force required to move pressure relief valve member 130 to the unseated position where this desired force is based on system requirements limiting pressure downstream of high-pressure fuel pump 20 that would be known to a person of ordinary skill in the art through strength and operating characteristics of fuel system 10. It should be noted that
Combination outlet valve and pressure relief valve 42 as described herein provides a common ground for outlet valve spring 122 and pressure relief valve spring 132. This arrangement may make inner housing 104 particularly well suited for manufacture by metal injection molding (MIM) which is desirable for efficient and cost effective manufacture. Additionally, one or more of outlet valve seat 118 and pressure relief valve seat 128 may be able to be utilized from existing designs taken from arrangements where the outlet valve and the pressure relief valve are not combined into one device. This eliminates the need for specialized seats which would add cost and complexity.
While high-pressure fuel pump 20 has been illustrated in the figures as including pressure pulsation dampers upstream of pump housing inlet passage 41, although not described herein, it should be understood that the pressure pulsation dampers may be omitted as a result of employing inlet valve assembly 40 which is a proportional valve. Furthermore, while check valve member 78 has been illustrated herein as a flat plate, it should be understood that check valve member 78 may alternatively be a ball biased by a spring which opens and closes a single valve body outlet passage 68.
While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
