GB2507747A

GB2507747A - Pump assembly for a fuel injection system; non-return valve

Info

Publication number: GB2507747A
Application number: GB1220079.6A
Authority: GB
Inventors: James Andrew Darley; James Kenneth Batchelor
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2012-11-07
Filing date: 2012-11-07
Publication date: 2014-05-14
Anticipated expiration: 2032-11-07
Also published as: WO2014072678A2; GB2507747B; WO2014072678A3; GB201220079D0; WO2014072678A4

Abstract

A pump assembly used in a fuel injection system, eg for a diesel engine, includes a non-return valve that assists in engine priming. The pump assembly further includes a transfer pump 23 supplying fluid to a high pressure, pump 12 which feeds a common rail 15. The non-return valve 28 fluidly connected between the high pressure pump 12 and the transfer pump 23 allows fluid to flow from the high pressure pump 12 to the transfer pump 23 and prevents reverse flow. A manual priming, eg hand-operated, pump 24 may be connected between the fuel tank 11 and a bypass circuit 25 around the transfer pump 23. A zero-delivery throttle 22 may be provided between an inlet metering valve 28 and an inlet of the transfer pump 23. The non-return valve comprises two connected members 29, 34 forming a chamber for a ball 33 which seats non-sealingly in one flow direction on a castellated nut 29 providing flow apertures and sealingly in the other flow direction on the mouth of a narrowed bore (39,fig.5) in member 34. Member 34 may comprise a banjo union fitting.

Description

A PUMP ASSEMBLY AND A VALVE

TECHNICAL FIELD

The present disclosure relates to a pump assembly and, in particular, the pump assembly of a fuel injection system, and a valve for use in said pump assembly, said valve being a non-return valve which assists in engine priming.

BACK CRC UND

Fuel systems used in internal combustion engines require priming before the fuel injectors are able to operate to start an engine. Diesel engines, in particular, may be hard to start if any vapour or air is entrained in the fuel system. Air can enter the system during filter replacement, when a fuel line is disconnected or when the operator has run out of fuel during operation of the engine.

Air may also enter the fuel system as a result of leaks and vapour can result from operation during low barometric conditions. Air in the system may cause impaired operation of the fuel system and water vapour in the fuel system may cause corrosion or dilution of the fuel.

In addition, on start up, a diesel engine requires fuel to be supplied continuously as soon as the engine is cranked, to prevent excessive wear in the engine. Air in the system may compromise the fuel supply.

In order to prevent problems associated with air getting in the fuel system, an operator may bleed the air out of the fuel lines when changing a fuel filter. Ihis is accomplished by loosening some fittings (injectors or lines) . Bleeding the air out of fuel lines is not a simple or fast process, and often requires manual operation by a skilled mechanic. Problems associated with air in fuel lines have sometimes been approached in the past by the use of one way check valves intended to keep fuel in the system, and thereby keep air out. However, the system might also be sensitive to the check valve seal wearing out.

Many diesel engines are therefore provided with priming devices to enable air to be purged more easily from the fuel system. One example of a priming device is a hand pump.

Although these pumps can be effective, an operator does not always have the knowledge or the patience to pump the number of strokes necessary to properly prime the engine before attempting to start it. Hand primers may also have functional limitations which mean that the air downstream of the filter may not be purged entirely.

Other features have been used in fuel systems in order to assist in priming the engine. For instance, it is known to include a bypass passage around the high pressure fuel supply pump or the transfer pump, which supplies fuel to the high pressure pump to improve the time needed to evacuate air or vapour from a fuel system. Such a bypass passageway typically includes a spring loaded valve that is lifted by prime pressure and enables the low pressure fuel circuit to be primed with fuel. The fuel may thereby bypass the pump, which is too restrictive for the pressure created by the priming pump. Another known system includes a bypass passage that circumvents both the fuel injectors and the pressure regulating valve. The bypass passage includes a hand manipulated valve that is only opened when the engine is off and being primed via a hand priming pump. The manual valve has an intentional leaking feature such that an operator can determine that the system is primed when fuel begins to squirt out of the leakage opening. When this occurs, the operator closes the manual valve and cranks the engine to start it in a conventional manner. In another known system, a bleed valve is positioned in a bypass passage around the pressure regulating valve. The bleed valve has a relatively low opening pressure threshold. The bypass passage also includes a flow restriction or orifice that passes gas without restriction but passes liquid with restriction, so as not to undermine the system pressure and the functioning of the pressure regulating valve.

SUMMARY

The present disclosure therefore provides a pump

assembly comprising: a first pump; a second pump fluidly connected to supply fluid to the first pump; and a non-return valve fluidly connected between the first pump and the second pump and defining a fluid passageway therethough; wherein the non-return valve allows fluid to flow through the fluid passageway from the second pump to the first pump, and prevents fiuid from flowing through the fluid passageway from the first pump to the second pump.

The present disclosure further provides a fuel system comprising: a fuel tank; at least one fuel injector; and the aforesaid pump assembly in which the second pump is a transfer pump fluidly connected to pump fuel from a fuel tank to the first pump, which is a high pressure supply pump fluidly connected to supply fuel to the at least one fuel injector.

The present disclosure further provides a non-return valve comprising: a hall; and a body comprising a first member and a second member; said first member having a distal and a proximal end, and a first fluid passage extending from the proximal to the distal end of the first member, the first member further comprising a ball seat at the distal end of the first member and at least one aperture extending between the first fluid passage through a wall of the first member; and said second member having a distal and a proximal end, and a second fluid passage extending from the proximal to the distal end of the second member, said second fluid passage comprising a first bcre section at the proximal end of the second member and second bore section extending from the first bore section towards the distal end of the second member, said first bore section having a greater diameter than the second bore section, and the second bore section having a diameter which is less than a diameter of the ball; wherein the distal end cf the first member is connected to the proximal end of the second member, with the first and second fluid passages being fluidly connected to form a fluid passageway, and thereby forming a chamber in which the ball is located, said chamber being defined by the first bore section and the distal end of the first member and the ball is movable between a non-sealing position, in contact with the ball seat, and a sealing position, in contact with a mouth of the second bore section.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is schematic illustration showing a fuel system comprising the pump assembly of the present

disclosure;

Figure 2 is a pictorial view of the pump assembly of the present disclosure that forms a part of the fuel system of Figure 1; Figure 3 is an exploded pictorial view of the valve used in the fuel system of Figure 1; Figure 4 is plan view of first member of the valve of Figure 3; and Figure 5 is a cross sectional side elevation of the valve of Figure 3 with a banjo bolt passing through the eye of the banjo section.

DETAILED DESCRIPTION

Figure 1 illustrates a fuel system 10 suitable for use in a diesel engine, comprising a pump assembly. The pump assembly comprises a high pressure fuel pump 12 that is fluidly connected to a fuel tank 11 by means of low pressure fuel lines 13, 46 and a transfer pump 23. The transfer pump 23, which may be a sliding vane pump, is fluidly oonnected between the fuel tank 11 and the high pressure pump 12. The transfer pump 23 assists in transferring fuel from the fuel tank 11 to the high pressure pump 12 via low pressure fuel line 13.

A primary fuel filter 14 may be located in the first fuel line 13. Fuel filter 14 may function to remove water, vapour and/or debris from the fuel before it is circulated around the fuel system 10.

The high pressure pump 12 may be fluidly connected to the transfer pump 23 via a second low pressure fuel line 46.

The high pressure pump 12 supplies fuei to a common rail via high pressure fuel line 17. Common rail 15 supplies fuel to a plurality of injectors 16. The high pressure pump 12 may thus provide an interface between the low and high pressure sides of the fuei system 10.

An inlet metering valve 18, or another pressure regulating valve, may be located in the second iow pressure fuel line 46 between the high pressure pump 12 and the transfer pump 23. The inlet metering valve 18, which may be a solenoid valve, controls the fuel intake to the high pressure pump 12. When the inlet metering valve 18 is open, a high fuel voiume intake is permitted, so that the high pressure pump 12 is fully filled and its pumping capacity is maximised. When the inlet metering valve 18 is closed, little or no fuei volume intake is permitted and the high pressure pump 12 is no longer being filled. In an alternate embodiment (not shown), the inlet metering valve 18 may be located in the primary fuel line 13. In yet another embodiment (not shown), an outlet metering valve may be located in the housing of the high pressure pump 12 to allow low pressure fuel to spill back to the fuel tank 11.

A secondary fuel filter 19 may also be located in the second low pressure fuel line 46 between the transfer pump 23 and the high pressure pump 12. This secondary fuel filter 19 may also remove debris from the fuel before it is fed to the injectors 16. The secondary fuel filter 19 may be provided with vent screws, which may be loosened to allow air carried by the fuel to escape.

The transfer pump 23 may also be fluidly connected to the fuel tank 11 via a low pressure fuel return line 20.

This enables a quantity of fuel to continuously flow back to the fuel tank 11. The fuel may be forced through a spill valve 21, which acts as an overflow valve. In this way, any air carried by the fuel is thus returned to the fuel tank 11. The common rail 15 may also be fluidly connected to the fuel tank 11 via the low pressure fuel return line 20.

A zero delivery throttle 22 may be fluidly connected between the inlet metering valve 18 and an inlet of the transfer pump 23 by means of a zero delivery line 27. This may provide a path for pressure decay after the inlet metering valve 18 by enabling fuel to flow from the suction side of the high pressure pump 12 back to the transfer pump 23. This may also provide a constant bleed of fuel, largely independent of the position of the inlet metering valve 18.

When the inlet metering valve 18 closes, it allows the fuel pressure to decay faster than in a system with no zero delivery throttle 22, and may therefore improve rail pressure control. Incorporating such a bleed down may prevent unnecessary pump plunger filling.

A priming pump 24, which may be a hand priming pump, may be fluidly connected between the fuel tank 11 and a bypass circuit 25, which circumvents the transfer pump 23, and which may be fluidly connected to the low pressure fuel line 46. The bypass circuit may include a bypass valve 26.

When cperated, the priming pump 24 may draw fuel from the fuel tank 11, through the primary fuel filter 14, to feed it to the bypass circuit 25 and into the second low pressure fuel line 46.

A non-return valve 28 is fluidly connected between high pressure pump 12 the transfer pump 23. The non-return valve 28 may be connected between the zero delivery throttle 22 and the zero delivery line 27. The zero delivery throttle 22 may be connected to an inlet of the high pressure pump 12. The zero delivery line 27 may be connected to an inlet of the transfer pump 23. The non-return valve 28 defines a fluid passageway therethough, which allows fluid to pass in one direction, from the high pressure pump 12 (via the zero delivery throttle 22) to the transfer pump 23, but prevents fluid from flowing in the opposite direction through the fluid passageway.

Referring to Figures 3 to 5, the non-return valve 28 comprises a first member 29, a second member 34 and a ball 33. The first member 29 may be a nut which has a castellated section 30 at a distal end of the first member 29, with a plurality of castellations 31 projecting there from. The upper surfaces 32 of the castellations 31 may be shaped to provide a locating seat for the ball 33. At least a portion of the outer surface of the castellated section 30 may be provided with a screw thread. The first member 29 may also have a central bore 35 providing a fluid passage extending from the distal to the proximal end of the first member 29.

The oastellations 31 provide a plurality of apertures extending from the oentral bore 35 through the wall of the first member 29.

The second member 34 may be a banjo union fitting, which has an annular (banjo) section 36 at its distal end connected to a sleeve 37 at its proximal end. The second member 34 may have a central bore 38 providing a fluid passage that extends from the proximal to the distal end of the second member 34. The central bore 38 may be stepped, having a narrower bore portion 39 communicating with the annular section 36, and wider bore portion 46 extending towards the free end of the sleeve 37. The free end of the sleeve 37 is also at the proximal end of the second member 34. The diameter of the narrower bore portion 46 may be is less than the diameter of the ball 33 so that when the ball 33 is in contact with the mouth of the narrower bore portion 39, it seals the bore 38. An inner surface of the free end of the sleeve 37 at the proximal end of the second member 34 may be provided with a screw thread, which Is complementary to the screw thread of the first member 29. The screw thread enables the first member 29 to be screwed into the second member 34. As an alternative to using screw threads to connect the first and seccnd members 29,34 they may be designed to be push fit together.

The first and second members 29, 34 may be connected to each other by locating the distal end of the first member 29 in the proximal end of the second member 34 with their respective fluid passages In fluid communIcatIon. This assembly may form a chamber 45 that is defined by the wider bore portion 40 and the distal end of the first member 29.

The ball 33 may be located in the chamber 45 and is movable -10 -between a first (non-sealing) position, in which it is located on the upper surfaoes 32 of the castellated section 30, and a second (sealing) position where it is in contact with the mouth of the narrower bore portion 39. The bore 35 of the first member 29 may be fluidly connected to an inlet of the transfer pump 23 via the zero delivery line 27.

A banjo bolt 41 may be used to fluidly connect the baujo end of the non-return valve 28 to the high pressure pump 12 via the zero delivery throttle 22. The banjo bolt 41 may have a longitudinal blind bore 42 and a transverse bore 43 that passes from one side of the bolt 41 to the other and intersects with the blind bore 42. The blind bore 42 may thus be fluidly connected directly or indirectly to the outlet of the high pressure pump 12. The banjo bolt 41 passes through the annular section 36 of the second member 34, with a washer 44 located on either side of the annular section 36. The zero delivery line 27 is fluidly connected to the first member 29 at the other end of the non-return valve 28.

The various component parts of the non-return valve 28 may be manufactured from stainless steel or another suitable material that is resistant tc corrosion from fuel.

INDUSTRIAL APPLICABILITY

When in operation, the fuel system 10 may be primed by operation of the priming pump 24. The priming pump 24 may be operated to draw priming fuel from the fuel tank 11 through the primary fuel filter 14 and to direct it to the bypass circuit 25, thus circumventing the transfer pump 23. The priming fuel may then be directed through the secondary fuel -11 -filter 19 up to the inlet metering valve 18. Air may be purged by opening the vent sorews in the seoondary fuel filter 19.

Simultaneously priming fuel is prevented by the non-return valve 28 from travelling along the zero delivery line 27 towards high pressure fuel pump 12 via the zero delivery throttle 22.

when the fuel system 10 is in normal operation, i.e. not being primed, fuel flowing from the zero delivery throttle 22 may flow along the zero delivery line 27 and may enter the distal end of the valve 28 via the blind bore 42 in the banjo bolt 41. The fuel may then pass out of the transverse bore 43, into the sleeve bore 38, around the ball 33, which is forced by the fluid pressure to seat on the upper surfaces 32 of the castellations 31. The ball 33 is thus moved it into its non-sealing position. The priming fuel may pass through the gaps between the oastellations 31 into the bore 35 of the first member 29, before passing out of the proximal end of the valve 28 and into the inlet of the transfer pump 23 for recirculation.

During priming, any fuel which travels along the zero delivery line 27 towards the zero delivery throttle 22 may enter the bore 35 of the first member 29 of the non-return valve 28. However, this forces the bali 33 out of contact with the castellations 31 and into its sealing position, in sealing contact with the mouth of the narrower bore portion 39 of the sleeve bore 38. In this position, the ball 33 may prevent any further flow of fuel through the non-return valve 28. The valve 28 thus prevents any back flow of fuel -12 -during priming. This helps to prevent air looks from forming in the fuel system 10 and to prevent contaminants from being flushed into the clean side of the fuel system 10. If the priming pump has sufficient oapability, this may ensure that the priming pump 24 is able to pump priming fuel at sufficiently high pressures to force it through the spill valve 21.

Although the non-return valve 28 has been described herein for use with a pump assembly of a fuel system, it may be used in any number of different applications, which may or may not include other types of pump assembly.

Claims

-13 -CLAIJYIS: 1. A pump assembly comprising: a first pump; a second pump fluidly connected to supply fluid to the first pump; and a non-return valve fluidly connected between the first pump and the second pump and defining a fluid passageway therethough; wherein the non-return valve allows fluid to flow through the fluid passageway from the second pump to the first pump, and prevents fluid from flowing through the fluid passageway from the first pump to the second pump.
2. A pump assembly as claimed in claim 1 further comprising a zero delivery throttle fluidly connected to the first pump, wherein the non-return valve is fluidly connected between the zero delivery throttle and the second pump.
3. A pump assembly as claimed in claim 1 or claim 2 in which the non-return valve comprises: a ball; and a body defining a fluid passageway in which the ball is located; wherein the ball is movable between a non-sealing position, in which fluid is able to flow through the fluid passageway from the zero delivery throttle to the second pump, and a sealing position, in which fluid is prevented from flowing through the fluid passageway towards the second pump.
4. A fuel system comprising: -14 -a fuel tank; at least one fuel Injector; and the pump assembly of any one of the preceding claims in which the second pump is a transfer pump fluidly connected to pump fuel from a fuel tank to the first pump, which is a high pressure supply pump fluidly connected to supply fuel to the at least one fuel injector.
5. A fuel system as claimed in claim 4 further comprising: a metering valve fluidly positioned between the transfer pump and the high pressure supply pump; a filter fluidly positioned between the transfer pump and the metering valve; a bypass flowpath circumventing the transfer pump; and a priming pump fluidly connected between the fuel tank and the bypass passage.
6. A fuel system as claimed in claim 5 in which the priming pump is a hand operated priming pump.
7. A fuel system as claimed in claim 5 or claim 6 further comprising a fuel return passage fluidly connected between the transfer pump and the fuel tank.
8. A non-return valve comprising: a ball; and a body comprising a first member and a second member; said first member having a distal and a proximal end, and a first fluid passage extending from the proximal to the distal end of the first member, the first member further comprising a ball seat at the distal end of the first member -15 -and at least one aperture extending between the first fluid passage through a wall of the first member; and said second member having a distal and a proximal end, and a second fluid passage extending from the proximal to the distal end of the second member, said second fluid passage comprising a first bcre section at the proximal end of the second member and seccnd bore section extending from the first bore section towards the distal end of the second member, said first bore section having a greater diameter than the second bore section, and the second bore section having a diameter which is less than a diameter of the ball; wherein the distal end cf the first member is connected to the proximal end of the second member, with the first and second fluid passages being fluidly connected to form a fluid passageway, and thereby forming a chamber in which the ball is located, said chamber being defined by the first bore section and the distal end of the first member and the ball is movable between a non-sealing position, In contact with the ball seat, and a sealing position, in contact with a mouth of the second bore section.
9. A valve as claimed In claim 8 in which the distal end of the first member is provided with a plurality of castellaticns having gaps therebetween, in which the gaps provIde the at least one aperture extending between the first fluid passage through the wall of the first member.
10. A valve as claimed in claim 8 or claim 9 in which the distal end of the second member comprises a banjo fitting, said banjo fitting comprising an annular section connected to a sleeve which defines said second fluid passage.Amendment to the claims have been filed as follows CLAIMS: 1. A pump assembly comprising: a first pump; a second pump fluidly connected to reoeive fluid from a storage tank and to supply fluid to first pump; a zero delivery line fluidly connected between upstream of the first pump and upstream of the second pump; a non- return valve located in the zero delivery line, said non-return valve defining a fluid passageway therethough; wherein the non-return valve allows fluId to flow through the fluid passageway from the first pump to the second pump, and prevents fluid from flowing through the fluid passageway from the second pump to the first pump. L52. A pump assembly as claiced in claim 1 wherein the zero delivery line comprises a zero delivery throttle fluidly connected downstream of the first pump, and the non-return r valve is fluidly connected between the zero delivery throttle and the second pump.3. A pump assembly as claiired in claim 1 or claim 2 in which the non-return valve comprises: a ball; and a body defining a fluid passageway in which the ball is located; wherein the bail is movable between a non-sealing position, in which fluid is able to flow through the fluid passageway from the zero delivery throttle to the second pump, and a sealing position, in which fluid is prevented from flowing through the fluid passageway towards the first pump.4. A pump assembly as claimed in claim 3 in which the body of the non-return valve comprises: a first member and a second member; said first member having a distal and a proximal end, and a first fluid passage extending from the proximal to the distal end of the first member, the first member further comprising a ball seat at the distal end of the first member and at least one aperture extending from the first fluid passage through a wall of the first member; and said second member having a distal and a proximal end, and a second fluid passage extending from the proximal to the distal end of the second member, said second fluid 0 passage comprising a first bore section at the proximal end of the second member and second bore section extending from the first bore section towards the distal end of the second member, said first bore section having a greater diameter than the second bore section, and the second bore section having a diameter which is less than a diameter of the ball; wherein the distal end of the first member is connected to the proximal end of the second member, with the first and second fluid passages being fluidly connected to form said fluid passageway, and thereby forming a chamber in which the ball is located, said chamber being defined by the first bore section and the distal end of the first member and the ball is movable between a non-sealing position, in contact with the ball seat, and a sealing position, in contact with a mouth of the second bore section.5. A pump assembly as clairred in claim 4 in which the distal end of the first member of the valve body is provided with a plurality of castellations having gaps therebetween, in which the gaps provide the at least one aperture extending between the first fluid passage through the wall of the first member.6. A pump assembly as clairred in claim 4 or claim 5 in which the distal end of the second member ot the valve body comprises a banjo fitting, said banjo fitting comprising an annular section connected to a sleeve which defines said second fluid passage.7. A fuel system comprising: a fuel tank; at least one fuel injector; and 0 the pump assembly of any one of the preceding claims in which the second pump is a transfer pump fluidly connected to pump fuel from a fuel tank to the first pump, which is a high pressure supply pump fluidly connected to supply fuel to the at least one fuel injector.8. A fuel system as claimed in claim 7 further comprising: a metering valve fluidly positioned between the transfer pump and the high pressure supply pump; a filter fluidly positioned between the transfer pump and the metering valve; a bypass flowpath circurr.venting the transfer pump; and a priming pump fluidly connected between the fuel tank and the bypass passage.9. A fuel system as claimed in claim 8 in which the priming pump is a hand operated priming pump.]0. A fuel system as claimed in claim 8 or claim 9 further comprising a fuel return passage fluidly connected between the transfer pump and the fuel tank. (4 aD r