The present invention relates to a fuel pump such as a diesel pump, and more specifically to a Transfer Pressure Regulator and a Fuel Temperature Sensor for a fuel pump.

BACKGROUND OF THE INVENTION

Known fuel pumps systems comprising a fuel transfer pump are usually provided with a regulator, to set the pressure of fuel feeding high and low pressure circuits of the pump, also known as the transfer pressure (TP).

An example of a known fuel pump system 100, i.e. a fuel pump hydraulic circuit, is illustrated schematically in Figure 1 and comprises a fuel pump 102, a high pressure connector 10, which connects the fuel pump 102 to a rail 11, and a low pressure connector 3, which connects the fuel pump 102 to a fuel tank 1.

The fuel pump 102, as illustrated separately in Figure 2, comprises a fuel transfer pump 4, a transfer pressure (TP) regulator 5, which sets the transfer pressure of the fuel feeding the high and low pressure circuits, and a temperature sensor 8, which measure fuel temperature at an inlet.

The known FTS 8, as illustrated in detail in Figure 3, comprises a connector 20, a canister 22, an FTS O-ring 24, and a sensor 26 such as a Negative Temperature Coefficient (NTC) thermistor.

The known TP regulator 5, as illustrated in detail in Figure 4, comprises a spring 60, a regulator plug 62, an end of which acts as a seat for the spring 60, a TP Regulator O-ring 64 surrounding the plug 62, and a piston 66. The TP Regulator 5 is fitted into a TP Regulator bore 18 (Figures 2 and 4) provided in a housing 107 (indicated on Figure 2) of the fuel pump 102, and the FTS 8 is fitted into a separate FTS bore 19 (Figures 2 and 3) in a front plate 109 (indicated on Figure 2) of the fuel pump 102. Each has an allocated link drill to allow being in contact with the fuel and performing their functions.

A complex assembly line is thereby required for assembly of the separate components of the known TP regulator and FTS assemblies.

Furthermore, the requirement for a separate bores and link drills for the TP Regulator and the FTS doubles the risk of creation of debris during machining and/or assembly; such debris could cause malfunction or failure of the fuel pump. The risk of external leaks is also increased by having two external components, and by having two separate O-rings.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved fuel pump which at least mitigates the problems as described above. Accordingly the present invention provides, in a first aspect, a fuel pump according to claim 1.

A protrusion of the fuel temperature sensor part may be located within a void above the Transfer Pressure Regulator part, such that the protrusion acts as a plug for the Transfer Pressure Regulator part.

A surface at or towards an end of the protrusion may act as a seat for a spring of the Transfer Pressure Regulator part. The present invention also comprises a fuel pump comprising a subassembly according to any one of the previous claims, wherein the subassembly is located within a bore of the fuel pump, and wherein the fuel temperature sensor measures temperature of fuel at an inlet of the fuel pump.

The present invention further comprises fuel pump system comprising a fuel pump as above.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which: Figure 5 is an isometric view of a fuel pump in accordance with the present invention;

Figure 6 is a cross-sectional view of a subassembly of the fuel pump of

Figure 5; and

Figure 7 is a schematic illustration of a system including the fuel pump of Figure 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiments of the present invention is described below in relation to the orientation of the figures. Terms such as upper, lower, above, below, top, bottom, horizontal and vertical are not intended to be limiting. Referring firstly to Figure 5, the present invention comprises a fuel pump 202, comprising a housing 207 and a front plate 209. A subassembly 250 is located in a bore 218 provided in the housing 207. The subassembly 250, as shown by itself in Figure 5, comprises a combined Transfer Pressure Regulator part (TP Regulator part) 105, and a Fuel Temperature Sensor part (FTS part) 108. The TP Regulator part 105 and FTS part 108 are both able to maintain the same functionality as the prior art components, within the subassembly 250.

The FTS part 108 of the subassembly 250 comprises a connector 120, remote from the TP Regulator part 105, and a sensor 126, such as a Negative Temperature Coefficient (NTC) thermistor. The TP Regulator part 108 comprises a piston 166, and a spring 160.

A protrusion 162 of the FTS part 108 is located in a void 168 comprising part of the bore 218 above the TP Regulator part 105; the protrusion acts as a TP Regulator plug. A surface 172, located at or towards an end 170 of the protrusion 162 remote from the connector 120, acts as a seat for the spring 160 of the TP Regulator part 105. An O-ring 164 surrounds, and is located within an annular groove 174 of, the protrusion 162.

Figure 7 illustrates schematically the fuel pump 202 of the present invention as part of a system 200, i.e. a hydraulic fuel pump circuit. The system 200 comprises a high pressure connector 110 which connects the pump 202 to a rail 111, and a low pressure connector 103, which connects the fuel pump to a fuel tank 101.

The fuel pump 202 comprises a subassembly 250 (TP regulator part 105 and FTS part 108), which sets the transfer pressure of the fuel feeding high and low pressure circuits whilst measuring the fuel temperature at the inlet.

The subassembly 250 of the present invention is located in a single bore 218 of the fuel pump 202; the bore 218 is equivalent to the bore 18 of the prior art in which only the TP Regulator 5 was located. Therefore in the present invention, there is no requirement for a further, separate bore and link drill(s) for the FTS part 108. Accordingly, the risk of any debris generated during machining leading to failure of the pump is reduced. The risk of external leaks is also reduced, and quality is improved.

Furthermore, because a separate bore for the FTS is not required, machining is cheaper and faster than for the prior art embodiment.

During assembly of the fuel pump 202, the fitting of a single subassembly 250, compared to the fitting of a separate TP Regulator 5 and FTS 8, is simpler and faster.

The present invention is also less costly than the prior art embodiment due to a lower component count, i.e. a further O-ring, and a separate TP Regulator plug, are not required. Having only one O-ring also further reduced the risk of external leaks.

REFERENCES

Prior art

fuel tank 1

low pressure connector 3

fuel transfer pump 4

TP Regulator 5

FTS 8

high pressure connector 10

rail 11

TP Regulator bore 18

FTS bore 19

FTS connector 20

FTS canister 22

FTS O-ring 24

FTS sensor 26

TP regulator spring 60

TP regulator plug 62

TP Regulator O-ring 64

TP regulator piston 66

fuel pump system 100

fuel pump 102

fuel pump housing 107

fuel pump front plate 109 Invention

fuel tank 101

low pressure connector 103

fuel transfer pump 104

TP Regulator part 105

Fuel Temperature Sensor part 108

high pressure connector 110

rail 111

(TP regulator part 105 + FTS part 108) bore 218 FTS connector 120

FTS sensor (NTC) 126

FTS spring 160

FTS protrusion 162

O-ring 164

FTS piston 166

TP Regulator void 168

FTS protrusion end 170

FTS protrusion surface 172

FTS protrusion annular groove 174

fuel pump system 200

fuel pump 202

fuel pump housing 207

fuel pump front plate 209

subassembly (TP regulator part + FTS part) 250