GB2570334A

GB2570334A - Configurable inlet valve of a fuel pump

Info

Publication number: GB2570334A
Application number: GB1801017.3A
Authority: GB
Inventors: Dodwell Simon; N Wray Jonathan
Original assignee: Delphi Technologies IP Ltd
Current assignee: Borgwarner US Technologies LLC
Priority date: 2018-01-22
Filing date: 2018-01-22
Publication date: 2019-07-24
Anticipated expiration: 2038-01-22
Also published as: GB2570334B; GB201801017D0

Abstract

An inlet valve assembly and a fuel pump are disclosed. The assembly comprises first 421 and second 422 base members, a valve member 136, a sleeve 142 and a spring 50 which are axisymmetric about a main axis Z. The end pieces 421,422 are identical and positioned face to face. The collar 142 is fixed over the valve stem 136 and the spring extends between the sleeve and one of the base members. The valve member has a lower end 140 that partially defines a compression chamber. The assembly may be configured either as normally open or normally closed, depending on the position of the biasing spring 50 in relation to the collar 142. A solenoid may or may not be used to allow for operation in an active or passive mode. The assembly allows for bespoke components to be replaced with interchangeable parts, which reduces the complexity of the design, manufacture, development and validation of such valves.

Description

TECHNICAL FIELD

The present invention relates to an inlet valve assembly of a fuel pump and, more particularly to the design of valve components enabling several assembly configuration.

BACKGROUND OF THE INVENTION

High pressure (HP) fuel pumps used in common rail diesel fuel injection systems have a piston reciprocating in a bore between BDC and TDC for compressing fuel in a compression chamber. Said pumps rely on a regulating valve to deliver the correct quantity of fuel to a HP fuel accumulator, also known as a “fuel rail”.

EP2706222 discloses a high pressure (HP) fuel pump which inlet valve assembly has a cylindrical valve member guided in a bore partially defining a compression chamber. In use, when said valve member is in an open position, the fuel at low pressure enters said chamber via a conduit axially drilled through said valve member and then, when said member commutes to a closed position the fuel at high pressure is expulsed from said chamber via said same conduit, the valve member sealing at an end around an outlet conduit controlled by a check valve.

Under the EP2706222 design principle, at least four variants of pumps can be designed, the valve disclosed in EP2706222 being a normally closed active valve wherein a solenoid works against a spring for controlling the moves to the valve member.

A normally open “passive” valve allows the compression chamber filling with every filling stroke of the piston (moving from TDC to BDC) and, the valve closes as a result of a pressure imbalance generated naturally during the pumping stroke of the piston (moving from BDC to TDC) the spring force being sufficiently less than the pressure imbalance force so the valve closes during the pumping stroke. The fuel delivery requires a separate inlet metering valve (IMV) to control the amount of fuel which is drawing into the pumping chamber during filling.

A normally open “active” valve comprises an actuator controlling the valve member and deciding the quantity of fuel to be delivered to the rail and the quantity to be spilt back to a low pressure supply circuit during the pumping stroke. Here the actuator force is greater than and opposes the spring force, and the spring force is always greater than and opposes the pressure imbalance force to avoid valve movement when no fuel delivery is demanded.

A normally closed “passive” valve opens as a result of a pressure drop in the pumping chamber which causes a force imbalance on the valve overcoming a spring load. A separate IMV is required.

A normally closed “active” valve, as is the valve of EP2706222, comprises an actuator controlling the valve member for holding the valve open during pumping to meter how much fuel is delivered to the rail. The actuator force is greater than and opposes the pressure imbalance force and spring force combined.

Bespoke components are required to achieve each of these pump variants, which increases complexity in design, manufacturing, development and validation.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing an inlet valve assembly of a fuel pump controlling the inlet to a compression chamber.

Said assembly comprises a first base member, a second base member, a valve member a sleeve, and a spring, all said members being substantially axisymmetric about a main axis Z. The first base member is substantially circular and annular having a first support face opposed to a first front face wherefrom a first annular wall protrudes toward a wall first annular end face. Said wall surrounds a central first recess having a bottom face in which centrally opens a first aperture, the bottom face annular area surrounding said opening defining a first base spring seat.

The second base member is identical to the first base member.

The valve member has a lower end partially defining said compression chamber and, the sleeve being fixed over the valve member, the sleeve extending from an end face engageable in the base member recess, to an opposed second end face defining an annular spring seat surrounding the valve member. Said assembly members are coaxially arranged, the first and second base members being face-toface, the first front face facing the second front face and leaving an open interspace between the first wall end face and the second wall end face.

The valve member extends through the first aperture of the first base and, the sleeve is fixed over the valve member so the spring seat defined by the sleeve second end face lies within said interspace.

The spring is compressed between the sleeve spring seat and one of the base spring seat.

The Valve may further comprise a tubular spacer arranged between said first and second base members.

The valve member may be cylindrical and provided with an axial through hole extending between said lower end face partially defining said compression chamber and, an upper end face where said hole opens and is surrounded by a seat face, said upper end face being proximal to and cooperating with the second support face, said hole enabling fuel to flow in and out of a compression chamber.

Said valve assembly may define a normally open valve, the assembly members being arranged so that the spring is compressed between the sleeve spring seat and the second base spring seat, the valve member upper face being urged away from the second base support face.

In another arrangement, said valve assembly may define a normally closed valve, the assembly members being arranged so that the spring is compressed between the sleeve spring seat and the first base spring seat, the valve member outer face being flush to the second base support face.

In yet another arrangement, the inlet member is a poppet valve having a stem on which is fixed the sleeve and a head cooperating with a seat face surrounding the opening of an inlet in the compression chamber.

Said valve assembly may define a normally open valve, the assembly members being arranged so that the spring is compressed between the sleeve spring seat and the second base spring seat, the head of the valve member being lifted from said seat face.

Said valve assembly may define a normally closed valve, the assembly members being arranged so that the spring is compressed between the sleeve spring seat and the first base spring seat, the head of the valve member being in sealing contact against said seat face.

The sleeve, may further be provided at its second end with an annular collar radially outwardly extending in said interspace, the collar defining a transverse annular active area in surface continuity with the sleeve spring seat, said active area defining a gap with the wall end face.

The inlet valve, may further comprise an annular solenoid adapted when being energised to generate a magnetic field, said solenoid being arranged between the two base members, the annular walls of said base members peripheral walls, being engaged in the central space of the solenoid. The sleeve may be made of magnetic steel for being attracted by said magnetic field.

The invention extends to a fuel pump wherein an inlet valve assembly as described above controls the fuel flow entering a compression chamber .

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

Figure 1 is an axial section of a passive normally open configuration of a valve as per the invention.

Figure 2 is an axial section of a passive normally closed configuration of a valve as per the invention.

Figure 3 is an axial section of an active normally open configuration of a valve as per the invention.

Figure 4 is an axial section of an active normally closed configuration of a valve as per the invention.

Figure 5 is an axial section of an inlet valve as per a second embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In reference to the figures is described a fuel pump 10 comprising a pumping unit 12, a head unitl4 and, an inlet valve assembly 16 A, 16P arranged between said units.

The pumping unit 12 has a body 18 provided with a bore 20 extending along a main axis Z opening at an upper end in the centre of an upper face 22 of the pumping unit 12 and, at a lower end (not shown) in a cambox. Said upper face 22 is substantially circular and transverse to said main axis Z, the opening of the bore 20 being surrounded by a peripheral wall 24 of height H24 protruding from said upper face 22 to a distant top face 26. In the bore 20, a piston (not shown) cooperating with a camshaft is urged to reciprocal displacements between BDC and TDC. The upper end portion of the bore defines a compression chamber 27 wherein fuel enters during a filling stroke, the piston moving from TDC to BDC, and is pressurised during a pumping stroke, the piston moving from BDC to TDC. At the very upper end of the bore is provided a leak path 28 comprising a peripheral groove dug in the bore and, from said groove a small hole angularly drilled through said wall 24, said leak path 28 separating high and low pressure areas by enabling fuel to leak back to a low pressure area.

The head unit 14 has a body 30 defining a large cylindrical recess 32 having a peripheral face 34 and a bottom face 36 shown toward the top of said recess 32 following the arbitrary orientation of the figures. Said bottom face 36 has a flat annular peripheral area surrounding a central protrusion defining a transverse face slightly elevated relative to said bottom face 36. In said body 30 axially extends an outlet conduit 38 opening at the centre of said slightly elevated transverse face, the peripheral area surrounding said outlet opening defining an annular seat 40. A non-retum outlet check valve (not shown) controlling the outlet conduit 38 is arranged in the head unit. Said outlet valve closes the outlet conduit and only opens to enable fuel to be expulsed from the compression chamber when the pressure therein exceeds a pressure threshold. On the exemplary embodiment a frustoconical protrusion is shown, but it could have another shape such as a cylindrical shape. In another alternative, the bottom face could be entirely flat without central protrusion, the opening of the outlet conduit still being surrounded by a valve seat.

As shown, the pumping unit 12 is inserted in the recess 32 of the head unit 14 defining a cylindrical void between the upper face 22 of the pumping unit, the bottom face 36 of the head unit and, the peripheral face 34 of the recess. In said void is arranged the inlet valve assembly 16A, 16P presented in four different configurations.

Said inlet valve assembly comprises a first base member 421, a second base member 422, a valve member 46, a tubular sleeve 48, a spring 50, an outer tubular spacer 52 in the configurations of passive valves (figures 1 and 2) and, in a configuration of an active valves (figures 3 and 4) said assembly 46 further comprises an annular solenoid 54, all said constituent members of the inlet valve assembly being axisymmetric about a main axis Z.

The first 421 and second 422 base members are strictly identical to one another eliminating part diversity and manufacturing complexity. The first 421 base member is arranged against the pumping unit and, the second base member 422 is arranged upside-down against the head unit, the two base members being maintained apart from one another by the tubular spacer 52 extending between the peripheral areas of said base members.

Said base member 421, 422 is substantially circular defining an annulus having a flat support face 561, 562 opposed to a front face 581, 582 wherefrom an annular wall 601, 602 protrudes toward an annular wall end face, 621, 622. Said wall surrounds a central recess 641, 642 having a bottom face 661, 662 in which centrally opens an aperture 681, 682 the annular area of the bottom face surrounding said opening defining a base spring seat 701, 702. In said paragraph the numeral reference of the features end by “1” when being a feature of the first base member 421 and by “2” when being a feature of the second base member 422.

Particularly, the first base member 421 lies against the upper face 22 of the pumping body and, the peripheral wall 24, surrounding the pumping bore opening, extends through said first aperture 681 of the first base member.

Moreover, the second base member 422 is arranged upside-down on the head unit side and, the end face of the conical protrusion wherein opens the outlet conduit 38 comes substantially flush with the second support face 562.

The second base member 422 faces the first base member 421 and, the spacer 52 keeps said base members in place facing one another and maintaining an interspace IS between the end faces, 621, 622 of the two annular walls.

The valve member 46 is substantially cylindrical having a peripheral face 72 axially extending between an upper end face 76 and a lower end face 74 engaged in the pumping bore 20 and partially defining said compression chamber 27, the valve member 46 being further provided with an axial through hole 78 drilled between said end faces 74, 76, the opening in the upper face 76 being surrounded by a seat face 80.

The tubular sleeve 48 is fixed by press fitted, or other fixation means, over the valve member 46, the sleeve 48 having cylindrical outer 82 and an inner 84 faces both coaxially extending between a first end face defining an annular spring seat 86 and a second end face defining an abutment face 88. The diameter of the outer face 82 is smaller than the inner diameter of the recess 641, 642 of the base member so that the sleeve can freely engage said recess.

The orientation of said sleeve 48 relative to the inlet valve member defines the valve configuration.

The inlet valve assemblies shown in figures 1 and 3 are configured as “normally open”. The sleeve 48 is oriented so the sleeve spring seat 86 faces the second base spring seat 702 of the second base member 422 and, the spring 50 is arranged compressed between said sleeve spring seat 86 and said second base spring seat 702 so that the valve member is urged, via the sleeve, toward an open position OP where, on the head side, the valve seat 80 is lifted away from the seat 40 of the head unit and, on the pumping unit side, the sleeve abutment face 88 is fully engaged in the first recess 641, said sleeve abutment face 88 being proximal the first bottom face 661.

The inlet valve assemblies shown in figures 2 and 4 are configured as “normally closed”. The sleeve 48 is reversed vis-a-vis the “normally open” and is oriented so the sleeve spring seat 86 faces the first base spring seat 701 of the first base member 421 and, the spring 50 is arranged compressed between said sleeve spring seat 86 and said first base spring seat 701 so that the valve member is urged, via the sleeve, toward a closed position CP where, on the head side, the valve seat 80 is sealing against the seat 40 of the head unit and, the sleeve is fully engaged in the second recess 642, said sleeve abutment face 88 being proximal the second bottom face 662.

A passive inlet valve 16P, shown on figures 1 and 2, moves between said open OP and closed CP positions as the result of a difference between the pressure in the compression chamber 27 and the pressure on the upper face of the valve member. During a filling stroke, the piston moves from TDC to BDC and, the compression chamber pressure drops aspiring the valve member to the open position OP, fuel being then able to enter said compression chamber 27 by flowing through the hole 78 of the valve and, during a pumping stroke when the piston moves from TDC to BDC the pressure in the compression chamber 27 raises and pushes the valve member 46 to the closed position CP where the seats 40, 80 get in sealing contact joining the valve hole 78 to the outlet conduit 38. As the pressure in the compression chamber reaches said threshold, the outlet check valve opens allowing the fuel pressurised to be expulses from the compression chamber.

An active valve 16A, shown on figures 3 and 4 further comprises an actuator controlling the valve member 46 as per the quantity of fuel required to be delivered to the rail and, the quantity to be spilt back to a low pressure supply circuit during the pumping stroke. Said actuator is the annular solenoid 54 cooperating with a magnetic armature. The solenoid 54 is arranged between the base members 421, 422, in the peripheral annular space comprised between the first and second walls 601, 602 and the spacer 52. Said solenoid is electrically connected to a command unit via electrical links. When being energised, the solenoid 54 generates a magnetic field that loops and attracts the magnetic armature that is integral to the sleeve 48. As shown on the figures 3 and 4, the sleeve 48 integrally comprises a collar member 49 that radially outwardly extends from the spring seat face 86. Said collar 49enlarges said spring seat face 86 with an annular active area 87 extending in the interspace IS, a gap G being defined between said active area 87 of the sleeve and the second wall end face 622, in the case of an active valve normally open (figure 3) and, the first wall end face 621 in the case of an active valve normally closed (figure 4).

In use when the solenoid is energised, the magnetic field loops following a path going through the gap G which attracts the sleeve, and then the valve member, toward the closed position (figure 3) or toward the open position (figure 4)·

In an alternative, a passive valve (figure 1 and 2) can be provided with a sleeve 48 integrating a collar 49, this enabling to manufacture and reference only one type of sleeve.

Moreover, following the same teachings for the design of the components, the valve member can integrate the sleeve with the collar.

A second embodiment of the invention is described in reference to figure 5. Said second embodiment of the pump 10 comprises a inlet valve assembly 110 sandwiched between a connector body 112 and a pumping body 18.

Similarly to the previous embodiment, the pumping body 18 is provided with the pumping bore 20 in which is guided a piston, the bore 20 opening on the upper face 22 of the pump body which, is this case is shown entirely flat.

The inlet valve assembly 110 is housed in a body 114 which lower face 116 covers the pumping body 18 and closes the bore 20, defining a ceiling face 118 to the bore. Said valve body 114 is provided with an inlet channel 120 which opens axially Z and centrally in said ceiling 118 and in the bore. Surrounding the opening 122 of the inlet, the valve body lower face 116 defines a valve seat 124. Moreover, slightly offset from the inlet opening 122, an outlet channel 126 extends in the valve body 114 from said ceiling face 118 and, in the figure, said outlet channel 126 is shown to be angled relative to the main axis Z. In said outlet channel 126 is arranged a non-return outlet check valve, not shown but similar to the valve arranged in the channel 38 in the first embodiment.

The valve body 114 is further provided with a recess defining a inlet valve chamber 128, said recess opening in the upper face 130 of the valve body, opposite to the lower face 116. A drilling 132, coaxial to the inlet opening 122 and extends in the body 114 between the bottom face 134 of the valve chamber and the lower face 116 of the body.

In said valve chamber 128 is arranged the inlet valve assembly 110, which differs from the previous embodiment mainly by the valve member 136 that is here a poppet valve having a stem 138 extending through the chamber 136, through said drilling 132 and protruding in the compression chamber 27 where the stem 138 is provided with a head member 140 that cooperates with the seat 124 surrounding the inlet opening 122.

Apart from this poppet valve member 136, the valve assembly 110 remains similar to the previous embodiment with a first base member 421, a second base member 422, a spring 50, an outer tubular spacer 52 and a sleeve 142 fixed to the stem 138 of the valve 136. Because of the thinner shape of the stem 138, the sleeve 142 is substantially a solid part provided with an axial drilling for inserting said stem. To lower the mass, the sleeve can be provided with a hollow, not shown.

LIST OF REFERENCES

Z main axis

H24 IS G OP CP	height of the wall interspace gap open position closed position
10 12 14 16 16A 16P 18 20 22 24 26 27 28 30 32 34 36 38 40 421 422 46	pump pumping unit head unit inlet valve assembly active inlet valve assembly passive inlet active valve assembly body of the pumping unit bore upper face of the pumping body peripheral wall top face the wall compression chamber groove and body of the head unit recess peripheral face bottom face outlet conduit seat first base member second base member valve member

sleeve collar spring spacer solenoid

561 first support face

562 second support face

581 first front face

582 second front face

601 first wall

602 second wall

621 first end face

622 second end face

641 first recess

642 second recess

661 first bottom face

662 second bottom face

681 first aperture

682 second aperture

701 first base spring seat

702 second base spring seat peripheral face of the valve member lower end face of the valve member upper end face of the valve member hole in the valve seat on the valve upper end face outer face of the sleeve inner face of the sleeve spring seat of the sleeve active area abutment face of the sleeve second embodiment - specific references

110 valve assembly

112 connector body

114 body of the valve assembly

116 lower face

118 ceiling face

120 inlet channel

122 inlet opening

124 seat

126 outlet channel

128 recess - valve chamber

130 upper face of the valve body

132 drilling

134 bottom face of the valve chamber

136 valve member - poppet valve

138 stem

140 head member

142 sleeve

Claims

CLAIMS:

1. Inlet valve assembly (16A, 16P, 110) of a fuel pump (10) controlling the inlet to a compression chamber, said assembly (16A, 16P, 110) comprising a first base member (421), a second base member (422), a valve member (46, 136), a sleeve (48, 142) and a spring (50), all said members being substantially axisymmetric about a main axis (Z) and, the first base member (421) being substantially circular and annular having a first support face (561) opposed to a first front face (581) wherefrom a first annular wall (601) protrudes toward a wall first annular end face (621), said wall surrounding a central first recess (641) having a bottom face (661) in which centrally opens a first aperture (681), the bottom face annular area surrounding said opening defining a first base spring seat (701) and, the second base member (422) being identical to the first base member and, the valve member (46, 136) having a lower end (74, 140) partially defining said compression chamber and, the sleeve (48) being fixed over the valve member, the sleeve extending from an end face (88) engageable in the base member recess, to an opposed second end face defining an annular spring seat (86) surrounding the valve member and wherein, said assembly members are coaxially Z arranged, the first (421) and second (422) base members being face-to-face the first front face facing the second front face and leaving an open interspace (IS) between the first wall end (621) face and the second wall end face (622) and, the valve member (46) extending through the first aperture (681) of the first base and, the sleeve (48, 142) being fixed over the valve member so the spring seat (86) defined by the sleeve second end face lies within said interspace (IS) and wherein, the spring (50) is compressed between the sleeve spring seat (80) and one of the base spring seat (40, 701, 702).

2. Inlet valve assembly (16A, 16P, 110) as claimed in the preceding claim further comprising a tubular spacer (52) arranged between said first and second base members.

3. Inlet valve assembly (16A, 16P) as claimed in any one of the preceding claims wherein the valve member (46) is cylindrical and is provided with an axial through hole (78) extending between said lower end face (74) partially defining said compression chamber and, an upper end face (76) where said hole opens and is surrounded by a seat face (80), said upper end face (76) being proximal to and cooperating with the second support face, said hole enabling fuel to flow in and out of a compression chamber (27).

4. Inlet valve assembly (16A, 16P) as claimed as in claim 3 wherein said valve assembly defines a normally open valve, the assembly members being arranged so that the spring (50) is compressed between the sleeve spring seat (86) and the second base spring seat (702), the valve member upper face being urged away from the second base support face.

5. Inlet valve assembly (16A, 16P) as claimed as in claim 3 wherein said valve assembly defines a normally closed valve, the assembly members being arranged so that the spring (50) is compressed between the sleeve spring seat (86) and the first base spring seat (701), the valve member outer face being flush to the second base support face.

6. Inlet valve assembly (110) as claimed in any one of the claims 1 or 2 wherein the inlet member (136) is a poppet valve having a stem (138) on which is fixed the sleeve (142) and a head (140) cooperating with a seat face (124) surrounding the opening (122) of an inlet in the compression chamber.

7. Inlet valve assembly (110) as claimed as in claim 6 wherein said valve assembly defines a normally open valve, the assembly members being arranged so that the spring (50) is compressed between the sleeve spring seat (86) and the second base spring seat (702), the head of the valve member being lifted from said seat face.

8. Inlet valve assembly (110) as claimed as in claim 6 wherein said valve assembly defines a normally closed valve, the assembly members being arranged so that the spring (50) is compressed between the sleeve spring seat (86) and the first base spring seat (701), the head of the valve member being in sealing contact against said seat face.

9. Inlet valve assembly (16 A, 16P, 110) as claimed in any one of the claims 3 to 8 wherein the sleeve (48, 142) is further provided at its second end with an annular collar (49) radially outwardly extending in said interspace (IS), the collar defining a transverse annular active area (87) in surface continuity with the sleeve spring seat, said active area defining a gap (G) with the wall end face.

10. Inlet valve assembly (16A, 16P, 110) as claimed in claim 9 further comprising an annular solenoid (54) adapted when being energised to generate a magnetic field, said solenoid being arranged between the two base members, the annular walls of said base members peripheral walls (601, 602) being engaged in the central space of the solenoid and wherein, the sleeve (48, 142) is made of magnetic steel for being attracted by said magnetic field.

11. Fuel pump (10) wherein an inlet valve assembly (16A, 16P, 110) as claimed in any one of the preceding claims controls the fuel flow entering a compression chamber (27).