FUEL PRESSURE REGULATOR

Abstract: A fuel pressure regulator has a base (10) having a rim (52) staked over a flange (40) of a pressure regulator cover (42), and a compression ring (44) concentrates the clamping effort of the cover on a circular area of a sealing region (36) of a diaphragm (16) of the pressure regulator.

Description: FUEL PRESSURE REGULATOR This invention relates to a fuel pressure regulator as specified in the preamble of claim 1, for example as disclosed in US-A-3 511 270. Some fuel injection systems for automotive engines have a plurality of fuel injectors each of which delivers fuel to the inlet port of an associated engine combustion chamber. In some such systems, the fuel injectors are mounted in sockets of a fuel rail which has a passage to supply fuel to the injectors; the fuel rail simplifies installation of the fuel injectors and the fuel supply passage on the engine. In such systems, a pump supplies more fuel to the fuel supply passage than is required by the injectors, and the excess fuel is discharged through a fuel pressure regulator as disclosed for example in the said US-A-3 511 270. In some applications, exemplified by the said US-A-3 511 270, the pressure regulator diaphragm is clamped between a sheet metal cover and a sheet metal base, and the base has a rim which is deformed over a flange of the cover to apply a clamping force to the cover and diaphragm. In other applications, exemplified by US-A-4 436 112, the pressure regulator diaphragm is clamped between a sheet metal cover and a machined base, and screws are employed to clamp the cover and the diaphragm to the base. The present invention is concerned with providing improved clamping and sealing in a fuel pressure regulator in which the pressure regulator diaphragm is clamped between a sheet metal cover and a machined base, without the use of screws to apply the clamping force. To this end, a pressure regulator in accordance with the present invention is characterised by the features specified in the characterising portion of claim 1. In a fuel pressure regulator in accordance with the present invention, the compression ring disposed between the cover and the diaphragm concentrates and maintains the clamping force on a circular area of the diaphragm. In the drawing: Figure 1 is a fragmentary sectional view, with parts in elevation, showing a portion of a fuel rail including a preferred embodiment of a fuel pressure regulator in accordance with the present invention; Figure 2 is an exploded view of a portion of the fuel pressure regulator shown in Figure 1; Figure 3 is a sectional view of a compression ring utilised in the fuel pressure regulator shown in Figures 1 and 2; and Figure 4 is a sectional view of a portion of the pressure regulator shown in Figure 1, enlarged to show details of the construction. With reference now to the drawing, a body 10 of an extruded fuel rail 12 is machined to form a base for a fuel pressure regulator 14. The pressure regulator 14 has a pair of diaphragms 16 which overlie one another to form a single diaphragm unit, and are clamped to and carry a central diaphragm retainer plate 18. A fuel chamber 20 is formed between the diaphragms 16 and the body (base) 10. The chamber 20 has a fuel access region 22 opening from a fuel supply passage 24, and a fuel outlet 26 opening through a valve seat 28 to a fuel return passage 30. The diaphragm retainer plate 18 carries a valve member 32 which co-operates with the valve seat 28, and a spring 34 biases the diaphragms 16 to engage the valve member 32 with the valve seat 28. The pressure regulator 14 controls fuel flow past the valve seat 28 to balance the fuel pressure in the chamber 20 on the diaphragms 16 with the bias of the spring 34, to thereby maintain a substantially constant fuel pressure in the chamber 20 and thus in the fuel supply passage 24. The diaphragms 16 have an annular sealing region 36 disposed between an annular clamping surface 38 formed in the body 10 and an annular flange 40 of a cover 42. A compression ring 44 is sandwiched between the flange 40 and the diaphragm sealing region 36. The compression ring 44 has a free inner edge 46, a circular intermediate area 48 engaging the diaphragm sealing region 36, and an outer edge 50 engaging the annular flange 40. The inner edge 46 of the compression ring 44 is spaced both from the diaphragms 16 and from the cover 42. The body 10 has a rim 52 surrounding and extending axially from the annular clamping surface 38. The rim 52 is staked over the annular flange 40 - for example by means of the staking tool 54 shown in Figure 2 - to cause the annular flange 40 to clamp the diaphragm sealing region 36 against the clamping surface 38. The flange 40 engages the outer edge 50 of the compression ring 44, so distorting the compression ring and causing the compression ring to concentrate the clamping effort of the flange 40 in the intermediate area 48 of the compression ring: The compression ring 44 is thereby effective to concentrate the clamping effort of the flange 40 on a circular area of the diaphragm sealing region 36. The concentrated clamping effort ensures a proper seal between the diaphragm sealing region 36 and the clamping surface 38. The compression ring 44 is also effective to maintain the clamping effort in the event that the staking force of the rim 52 relaxes in the course of time. A bead 56 on a tie rod 58 is captured by a ring 60 secured to the diaphragm retainer plate 18, and a head 62 of the tie rod 58 is captured behind a spring seat 64. The tie rod 58 thus limits movement of the spring seat 64 away from the diaphragm retainer plate 18, to simplify assembly of the pressure regulator 14. An end 66 of the cover 42 overlies the spring seat 64 and is axially deformable to move the spring seat 64 away from the tie rod head 62 towards the diaphragm retainer plate 18; the spring 34 is thereby compressed to increase the bias on the diaphragms 16 and thus increase the fuel pressure in the chamber 20 and the supply passage 24. A hose is connected between a fitting 68 on the cover 42 and the engine induction system to vent the interior of the cover 42.

Claims: Claims: 1. A fuel pressure regulator comprising a pressure regulator base (10) having an annular clamping surface (38), a pressure regulator diaphragm (16) having an annular sealing region (36) overlying the clamping surface (38), and a cover (42) having an annular flange (40) overlying the sealing region (36), the base (10) having a rim (52) surrounding and extending axially from the clamping surface (38), and the rim (52) being staked over the flange (40) to cause the flange (40) to clamp the diaphragm sealing region (36) against the annular clamping surface (38), characterised in that an annular compression ring (44) is disposed between the flange (40) and the diaphragm sealing region (36), and the compression ring (44) has an inner edge (46) spaced from the diaphragm (16), a circular intermediate area (48) engaging the diaphragm sealing region (36), and an outer edge (50) engaging the flange (40), the compression ring (44) being effective to concentrate the clamping effort of the flange (40) on a circular area of the diaphragm sealing region (36). 2. A fuel pressure regulator according to claim 1, characterised in that the inner edge of the compression ring (44) comprises a free inner edge (46) which is spaced from the diaphragm (16) and from the cover (42).

Inventors: FIELD, MARTIN JOHN
Applicants: GENERAL MOTORS CORPORATION
Application year: 1985
Main classification: G05D16
IPC codes: F02M69, G05D16, F16K17