FLUID PRESSURE REGULATOR TECHNICAL FIELD

The present invention relates to a pressure regulator adapted to be arranged in a fuelling equipment of an internal combustion engine.

BACKGROUND OF THE FNVENTION

A fuelling equipment of an internal combustion engine comprises a feed pump module immersed in a reservoir and adapted to suck and deliver the fuel therein stored to a high pressure pump. A very precise fuel pressure regulator is arranged between the two pumps to ensure that the pressure of the delivered flow does not exceed a predetermined threshold. Such regulator 1, as shown on figure 1, has a body comprising a cup-like housing 2 closed by a press-fitted cover 3, said body enclosing a spring loaded valve member 4 urged toward a closed position of a return fluid path A to the drain.

To ensure the level of required accuracy, each of said regulators 1 must be individually calibrated after assembly. This process is done by arranging the regulator in a fluid flow and by adjusting the axial position of the cover 3 inside the housing 2, thus tuning the compression of the spring. Because of the parts resiliency such fine positioning requires several consecutive steps, each moving the cover by few tenth of millimetres.

The regulator 1 , whose apparent design simplicity is balanced against a metal body and the long calibration process, ends up being a technical complex assembly having a high cost that is no longer suited to current requirements.

SUMMARY OF THE FNVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a pressure regulator adapted to be arranged in a pump module of an internal combustion engine fuelling equipment, said pressure regulator comprising an tuning feature adapted to adjust to a predetermined force a spring loaded valve member controlling a fluid path.

Said tuning feature may define a first thrust face cooperating with said spring for adjusting the spring load. Also, said spring load is may be adjusted by varying, along a main axis, the elongation of the spring and, the first thrust face is the peripheral face of an eccentric, or of a cam, integral to a shaft member extending along a shaft axis angled to said main axis.

Also, the shaft axis may be is perpendicular to the main axis.

Also, the pressure regulator may further comprise a regulator body defining an inner space wherein are arranged the spring loaded valve member and the tuning feature, and wherein the shaft extends across said inner space.

The shaft may be held between a first bearing and a second bearing arranged in said body.

Also, the body may be plastic moulded.

Also, the pressure regulator may further comprise a locking feature adapted to hold the spring loaded valve member in a position where said predetermined force is met.

Also, said locking feature may comprise a key member and a

complementary key hole enabling engagement in a plurality of locked positions.

Also, said locking feature may further comprise a resilient clip member integral to the spring loaded valve member cooperating with an edge integral to the tuning feature.

Also, said key member may be provided with teeth and said key hole is provided with slots, the teeth and the slots being arranged complementary engagement.

Also, said locking feature may be partially defined in the regulator body.

In an embodiment, the tuning feature and the locking feature may be integral to a monobloc stop member.

In another embodiment, the tuning feature and the locking feature are independent members cooperating together.

In any embodiment, the pressure regulator may further comprise tool engagement means enabling complementary engage a tool to operate the tuning feature and the locking feature during calibration of the regulator.

The invention further extends to a pump module of an internal combustion engine fuelling equipment provided with a pressure regulator as described above. The fuel may be gasoline.

The invention further extends to a method of calibration of a pressure regulator, the method comprising the following steps:

a) providing a pressure regulator as claimed in claim,

b) engaging a tool in the tool engagement means;

c) calibrating said regulator in a liquid free environment by locking the position of the spring loaded valve member.

Also, the calibrating step c) may comprise the following steps:

d) varying the force applied to the spring loaded valve member by operating the tuning feature,

e) monitoring said spring force during step d),

f) freezing the position of the spring loaded valve member by operating the locking feature when the spring force monitored at step e) equates the predetermined force.

Also, for the pressure regulator provided at step a), the varying step d) may be executed by rotating the shaft member about said shaft axis so that the eccentric, or cam, peripheral face urges the spring to vary its elongation.

Also, for the pressure regulator provided at step a), the locking step f) may be executed by engaging the key member in the key hole when the spring force monitored at step e) equates the predetermined force.

Also, for the pressure regulator provided at step a), the varying step d) and locking step f) may be executed in operating the same tool adapted to rotate the shaft and to push the shaft engaging the key member in the key hole.

Also, the calibrating step c) comprises the steps:

g) varying the force applied to the spring loaded valve member by operating the compressing the spring loaded valve member,

h) monitoring said spring force during step d),

i) freezing the position of the spring loaded valve member when the spring force monitored at step h) equates the predetermined force.

Also, for the pressure regulator provided at step a), the varying step g) may be executed by compressing the spring about said main axis with a tool. Also, for the pressure regulator provided at step a), the locking step f) may be executed by engaging the key member in the key hole when the spring force monitored at step h) equates the predetermined force.

Also, for the pressure regulator provided at step a), the varying step g) may be executed in operating a first tool and, the locking step is executed in operating a second tool adapted to rotate the shaft and to push the shaft engaging the key member in the key hole.

The invention further extends to a method of assembly of a pump module, the method comprising the following step:

g) providing a pump module,

h) providing a pressure regulator already calibrated in following the calibration method as detailed above.

The invention further extends to a calibration machine adapted to execute a calibration method as described 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 1 is a section of a pressure regulator of the prior art.

Figure 2 and 3 are two 3D views of a pressure regulator as per the invention represented in semi-translucent views.

Figure 4 is an exploded view of the regulator of figures 2 and 3.

Figures 5, 6 and 7 are 3D view of the body of the pressure regulator of figures 2 and 3.

Figure 8 is a 3D view of a spring loaded valve member of the pressure regulator.

Figures 9 and 10 are 3D views of a front spring cup part of the spring loaded valve member of figure 8.

Figures 11 and 12 are 3D views of a rear spring cup part of the spring loaded valve member of figure 8.

Figures 13, 14, 15 and 16 are 3D-views of an stop member of the spring loaded valve member of figure 6. Figure 17 is an axial section of a detail of the regulator in an open position.

Figure 18 is an axial section of a detail of the regulator in an closed position.

Figures 19, 20, 21 illustrate steps of a calibration method of the regulator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A fuelling equipment of an internal combustion engine comprises a feed pump module 8, not shown, immersed in a reservoir and adapted to suck and deliver the fuel via a delivering pipe joining a high pressure pump. In reference to figures 2, 3 and 4 is presented a pressure regulator 10 as per the invention adapted to be arranged in said fuelling equipment to open a return fluid path for a portion fuel to return directly to the reservoir when the pressure exceeds a threshold.

Although having a design that seems at first sight more complex than the prior art regulator, said regulator 10 is easier to manufacture, easier to calibrate and, at the end of the production line all parameters taken into account, it is much cheaper than the prior art regulator 1.

The regulator 10 comprises a plastic molded body 12 in which is arranged a spring loaded valve member 14 maintained in place by a stop member 16 integrally defining an tuning feature 18 and a locking feature 20.

The regulator component are now individually described and, in reference to figures 5, 6 and 7, the body 12 is plastic molded forming an integral monobloc part having a cylindrical shape extending about a main axis X. Said body 12 defines an inner space S surrounded by a peripheral cylindrical wall 22 closed at an end by a transverse wall 24. Moreover, a fluid path A routes through said body

12 between an inlet 26 defined in said transverse wall 24 and an outlet 28 defined in the cylindrical wall 22.

As visible on the figures, the inlet 26 is defined as a channel extending in a turret 30 axially X outwardly extending from the transverse wall 24. Internally to the inner space S, the transverse wall 24 defines a flat face 31 at the center of which opens said inlet channel 26, said opening being surrounded by an annular lip 32 rising to a height H32 above the said flat face 31. The lip 32 is particularly shown on figures 7, 17 and 18. In a front portion 34 of the cylindrical wall, in the vicinity to said transverse wall 24, the outlet 28 is defined by a plurality of open windows, four in the present example, shaped as curved rectangles separated by upward legs holding together a rear portion 36 of the cylindrical wall.

The spring loaded valve member 14, shown on figure 8, is an assembly comprising a compression coil spring 38 holding at a front end a front spring cup 40 and a closure member 42 and, at an opposite rear end a rear spring cup 44.

The front spring cup 40, described in reference to figures 9 and 10, is a plastic molded part comprising a transverse disc 46 and a positioning protrusion 54. The transverse disc 46 defines on a front side a flat face 48 provided with a central positioning hollow 50 and, at the periphery of said face 48 three small fingers 52 rise above said face 48 to a height H52. Alternatively another front cup may be provided with four fingers or more or, even with a 360° annular wall surrounding said face 48. Opposite said front face 48, axially extends the positioning protrusion 54 having a slightly beveled shape for easy insertion in the lasts turns of the spring 38, said last turns abutting an annular area of the disc surrounding said protrusion 54. The insertion of the positioning protrusion 54 in the turns of the spring is free as the section of said positioning protrusion 54 narrows as it extends away from the disc 46. To ease the handling of the assembly the positioning protrusion defines a small zone 55 of interference with the very last turn of the spring, this interference being sufficient to hold the front cup 40 in the spring and to handle the parts without risking to disassemble. The closure member 42, shown on figures 4 and 8, is a rubber-like flat disc defining a front closure face 56 opposed to a back face provided with a central locating member 60. In place, said flat disc is against the front face 48 of the front cup and, the locating member 60 is inserted in the hollow 50.

At the rear end of the spring 38, the rear spring cup 44 described in reference to the figures 11 and 12, is also an integrally plastic molded component comprising a base portion 62 wherefrom on one side extends a beveled positioning member 64 surrounded by a peripheral annular face and, defining on the opposite side a flat transverse thrust face 66 and a resilient clip member 68. Similarly to the front end, the beveled positioning member 64 and the peripheral annular face are designed for engaging and abutting the last turns of the spring. Also, the insertion in the turns of the spring is free becaused of the beveled shape of the positioning protrusion 64 and similarly, to ease the handling of the assembly said beveled shape enlarges in the vicinity of the base 62 defining a small zone of interference with the very last turn of the spring, this being sufficient to hold the front cup 40 in the spring.

The clip member 68 comprises a resilient curved leg upwardly rising from the base 62 to a distant edge 70 that, in absence of solicitations, rests above the level of the thrust face 66. On the example shown, said clip comprises two curved legs linked by a joining member defining said edge 70. Furthermore, the rear spring cup 44 comprises a pair of ears 72 upwardly extending from the base 62 toward distant arcuate faces 74 adapted to receive in abutment a compression tool Tl . Said ears 72 are opposite portions of a cylinder surrounding said thrust face 66 and, they are separated for the stop member 16 to extend in between.

The stop member 16, described in reference to figures 13 to 16, extends along a transverse axis Y that perpendicularly intersects the main axis X, said stop member 16 comprising a shaft 76 at an end of which is arranged a key member 78. The stop member 16 is arranged in the rear portion 36 of the body cylindrical wall, shown in figures 5, 6 and 7, between a first bearing 80 and a second bearing 82 coaxial to said transverse axis Y. The first bearing 80 is a relatively small cylindrical opening defining a first female face in the thickness of said rear portion 36 of the cylindrical wall and, the second bearing 82 is a cylindrical opening of larger diameter defining a second female face in the thickness of said rear portion 36 of the cylindrical wall.

The shaft 76 comprises a cylindrical first end 84 complementary to the first bearing 80, an eccentric cylinder 86, and a large cylindrical second end 88 complementary to the second bearing 82. Between said first 84 and second 88 ends, the eccentric cylinder 86 has a circular cross-section which diameter is intermediate between the small section of the first end 84 and the large section of the second end 88. As shown, it is decentred relative to transverse axis Y extending about an eccentric axis distinct and parallel to said transverse axis Y. Furthermore, the cylindrical face of the eccentric 86 is divided by as annulus 90 rising slightly above the face of the eccentric and forming a 360° annular step defining a circular edge 92 oriented toward the key member 78, said edge 92 cooperating with the clip 68 to define an axial Y part of the locking feature

20. Alternatively to an eccentric that has a circular cross-section, the stop member can be provided with a cam having an ovoid section.

The key member 78, integral to the second end of the shaft, has a disc- like shape and is coaxial to the transverse axis Y and to the first 84 and second 88 ends. It is arranged to cooperate with a complementary key hole 94 provided on the external face of the rear portion 36 of the cylindrical wall.

On the inner face of said disc-like member, face oriented toward the shaft, the key member 78 comprises a plurality of radial teeth 96 evenly angularly distributed, the example shown having five teeth 96 regularly arranged at 72° of one another.

The key hole 94, particularly visible on figure 6, forms on the external face of wall 36 a circular annular face 98 transverse to said transverse axis Y and surrounding the second bearing. Said key hole 94 is provided with a plurality of slots 100, thirty in the example shown, radially oriented and regularly distributed every 12°. The teeth 96 and the slots 100 are designed for complementary engagement forming an angular part of the locking feature 20. The angle between two consecutive teeth 96 is therefore a multiple of the angle between two consecutive slots 100.

On the stop member 16, the outer face 102 of the disc-like member, face opposite the teeth 96, is provided with an engagement means 104, which in the example shown comprises a plurality of circular hollows regularly arranged around said outer face for complementary engagement of an adjusting tool T2. Other features such as a radially extending slot or a male or female hexagon may be used in other alternatives.

The pressure regulator 10 assembles as shown on figures 2, 3 and 4. At the rear end of the spring loaded valve member 14 is arranged the rear spring cup 44, its positioning member 64 being engaged and slightly press-fitted in the lasts turns of the spring, the thrust face 66 being opposed to the spring. At the front end of the spring are the front spring cup 40 and the rubber disc closure member 42.

The valve member 14 is inserted in the inner space S of the body, the closure member 42 oriented toward the inlet 26 so the rubber disc engages the lip 32. As shown on the figures 17, 18, the fingers 52 are provided to prevent damage of the rubber disc 42. Indeed, the spring pressurises said rubber disc against the lip 32 and, after few tenth of millimetres of compression of the rubber, the fingers 52 abut the flat face 31 and thus limit said rubber compression to said few tenth of millimetres which, is sufficient to ensure sealing without over-compressing and damaging the rubber disc 42. The design dimensional relationship between the heights and thickness involved as presented on figures 17 and 18 is as follow:

H32 + T42 = H52 + C

where, C is the maximum compression seen by the rubber disc and, as already known H32 is the height of the lip, T42 the thickness of the rubber closure member and H52 the height of the fingers. Figure 17 shows the regulator in an open position of the inlet 26, the closure member 42 just contacting the tip of the lip 42 and, figure 18 shows the regulator in a closed position of the inlet 26, the closure member 42 being pressed onto said lip 42 which locally compresses the rubber disc, said compression being limited by the fingers 52.

Models and tests have been successfully performed with the following dimensions:

H32 = 1 mm; T42 = 1.5 mm; H52 = 2.2 mm, and consequently C = 0.3 mm.

The stop member 16 is arranged in the rear portion 36 of the cylindrical wall between the first 80 and the second 82. The spring 38 is compressed between the closure member 42 that is pressed onto the lip 32 and, the thrust face 66 of the rear spring cup that is pressed on the cylindrical face of the eccentric 86. The stop member 16 is locked in an angular position by inserting the teeth 96 of the key in the slots 100 of the key hole, the number of angular positions in which said stop member 16 may be locked being the number of slots 100 of the key hole. In each of said locking position the eccentric 86 is rotated to a different position varying the spring compression. In the example shown where the key hole 94 has thirty slots 100, the stop member 16 can locked in thirty different angular positions, one position every 12°.

In operation, the pressure regulator 16 rests in a closed position of the inlet 26, the spring being compressed at a predetermined calibration force F. The fluid pressure in the inlet channel 26 generates on the valve member an opening force opposite to the closing compression force of the spring. As long as the fluid pressure remains below a threshold value, said opening force is smaller than said calibration force F and the regulator remains in closed position. When the fluid pressure reaches and exceeds said threshold value, the opening force becomes predominant over the spring force and the spring further compresses and opens the inlet 26 thus enabling fluid in excess to bypass the normal fluid circuit and to return to a reservoir via the inlet 26 and the outlet 28 of the regulator.

Calibrating the regulator 10 can be done following at least two methods 200, 300 now described in reference to the figures 19, 20 and 21, both methods starting by assembling the spring loaded valve member 14 with the front 40 and rear 44 cups and the closure member 42 and, arranging said spring loaded valve member 14 in the body 12. As shown on the figures, the valve member 14 has to be oriented so the ears 72 rear cup member 44 are substantially parallel to the transverse axis Y and not obstructing the space between the bearings for enabling the insertion of the stop member 16.

The first method 200 continues with the following steps:

- arranging 212 said body 12 and valve member 14 assembly on a machine adapted to measure the force of the spring. For instance, said machine can firmly hold the body 12 in a feature provided with a force sensor, such as a strain gauge, said sensor delivering a signal relevant to the compression force of the spring.

- monitoring 214 the compression force of the spring.

- engaging 216 a compression tool Tl over the rear spring cup, as shown on figure 19, so that said tool Tl axially X pushes on the arcuate top faces 74 of the ears 72 and compresses the spring. The spring is to be compressed sufficiently to clear the space between the first 80 and second 82 bearings as it is particularly shown on figure 6.

- inserting 218 the stop member 16 in the body by engaging it in said clear space through the opening of the second bearing so that it is held in an initial position as shown on the figure 20 between the bearings 80, 82. In said initial position the stop member 16 is unlocked since the teeth 96 of the key are not inserted in the slots 100 of the key hole.

- removing 220 the compression tool Tl, enabling the spring to expand the thrust face 66 being pressed against the circular face of the eccentric. - engaging 222 an adjustment tool T2 in the engagement means 104 of the outer face 102 of the disc-like member of the stop member 16, as shown on figure 20.

- by using said adjustment tool T2, rotating 224 the stop member 16 about the transverse axis Y, the compression of the spring being varied during this operation.

- freezing 226 the position of the stop member when the compression force monitored at step 214 equates the predetermined calibration force F, said freezed position being a calibration position PC.

- locking 228 the stop member in said calibration position PC by further pushing it and by inserting the teeth 96 of the key into the slots 100 of the key hole. In said calibration position, the stop member 16 is angularly locked by said teeth and slot cooperation and, it is also axially locked since the eccentric has moved and the clip has relaxed for its edge 70 to lock against the circular edge 92 of the annulus preventing disengagement of the stop member.

Alternatively to said first method 200, the second method 300 continues, after the initial assembling and arranging steps with the following steps:

- arranging 312 said body 12 and valve member 14 assembly on a machine comprising a locking feature adapted to maintain the regulator in place and, a compression tool Tl provided with a force sensor adapted to measure the axial X force said tool Tl generates and applies to the spring.

- monitoring 314 the compression force of the spring.

- engaging 316 the compression tool Tl over the rear spring cup, as shown on figure 19 so that it axially X contacts the top face 74 of the ears 72 and is ready to compress the spring.

- compressing 318 the spring 38 with said tool Tl .

- freezing 320 the compression position when the compression force monitored at step 314 equates the predetermined calibration force F.

- inserting 322 the stop member 16 in the body and, freely rotating the stop member until the face of the eccentric 86 comes in contact against the thrust face 66, without further compressing the spring.

- locking 324 the stop member in the calibrated position PC by further pushing it and by inserting the teeth 96 of the key into the slots 100 of the key hole. In said locked calibrated position PC the annulus 90 of the eccentric moves forward away from the clip member 68 that relaxes for the clip edge 70 to engage the annulus edge 92 and axially Y locks the stop member 16 in axial position preventing later disengagement.

Both methods 200, 300 ends with an ending step where the tools are removed and the calibrated regulator 10 is removed from the machine.

LIST OF REFERENCES

A fluid path

X main axis

Y transverse axis

H32 height of the lip

H52 height of the finger

T42 thickness of the closure member

Tl compression tool

T2 adjusting tool

F calibration force

1 prior art - pressure regulator

2 prior art - housing

3 prior art - cover

4 prior art - valve member

8 pump

10 pressure regulator

12 body

14 spring loaded valve member

16 stop member

18 tuning feature

20 locking feature

22 peripheral cylindrical wall

24 transverse wall

26 inlet - inlet channel

28 outlet

30 turret

31 flat face

32 lip

34 front portion of the cylindrical wall

36 rear portion of the cylindrical wall

38 spring

40 front spring cup 42 closure member

44 rear spring cup

46 disc

48 front face

50 hollow

52 finger

54 positioning protrusion

55 interference zone

56 closure side

58 back side

60 locating member

62 base portion

64 positioning member

66 thrust face

68 clip member

70 edge

72 ear

74 top face

76 shaft

78 key member

80 first bearing

82 second bearing

84 first end

86 eccentric

88 second end

90 annulus

92 circular edge

94 key hole

96 teeth

98 annular face

100 slots

102 outer face

104 engagement means

200 Method

212 arranging step

214 monitoring step

216 engaging step

218 inserting step

220 removing step

222 engaging step

224 rotating step

226 freezing step locking step method arranging step monitoring step engaging step compressing step freezing inserting step locking step