WO2018146340A1

WO2018146340A1 - Damper

Info

Publication number: WO2018146340A1
Application number: PCT/EP2018/053594
Authority: WO
Inventors: Karolis SERENAS; Michael Jarvis
Original assignee: Delphi Technologies Ip Limited; Delphi France Sas
Priority date: 2017-02-13
Filing date: 2018-02-13
Publication date: 2018-08-16
Also published as: GB2559612B; GB201702328D0; GB2559612A

Abstract

A damper device (28) adapted to be arranged in a high pressure fuel pump (12) comprising a capsule (40) held in a rubber holder (48) maintained by a metallic plug (50).

Description

DAMPER TECHNICAL FIELD

The present invention relates to a high pressure fuel pump and more particularly to, a damper device arranged in the pump cambox housing and adapted to amortise pressure peaks in said cambox. BACKGROUND OF THE INVENTION

In a fuel injection equipment of an internal combustion engine, fuel is pressurised in a pump wherein a piston urged by a rotating camshaft reciprocally varies the volume of a compression chamber. Pump efficiency and packaging drives toward single piston design also known for generating high pressure fluctuations in the low pressure cambox. Complex and expensive dampers have been designed and arranged in the low pressure circuit of the equipment, including in the wall of the pump housing in order to amortise said fluctuations.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to solve or at list mitigate the above mentioned problems in providing a damper device adapted to be arranged in an aperture provided through a peripheral wall of a cambox of a high pressure fuel pump in order to attenuate low pressure fluctuations occurring in use, in said cambox. Said damper device comprises a damper capsule held in a capsule holder maintained in position in said aperture by a metallic plug adapted to seal said aperture wherein, said capsule holder is made of rubber material.

Also, said damper capsule comprises pressurised gas captured between two diaphragms arranged against each other and bounded together by their circular edge thus forming the capsule edge. The capsule holder has an annular shape defining an inner annular face surrounding an inner space in which said capsule is arranged, the capsule edge being inserted in an annular groove provided in said inner annular face.

Also, said annular holder is crenulated forming a plurality of rubber blocks rising over a common annular base.

In an alternative, the capsule holder comprises at least one plastic insert overmoulded in the rubber material. Said plastic insert may be a closed annulus.

In a first embodiment, the capsule holder is integrally bounded to the metallic plug.

In a second embodiment, the capsule holder and the metallic plug are distinct parts non-attached to one other.

The invention further extends to a fuel pump having a cambox in which, in use, a camshaft rotates, imparting reciprocal displacements to a piston. An aperture is provided through the peripheral wall of said cambo and, a damper device as previously described is arranged in said aperture.

Also, said aperture defines a peripheral face and a shoulder face, the damper device being arranged so the capsule holder abuts against said shoulder, the damper capsule being substantially transverse to the aperture.

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 high pressure pump in which is arranged a damper device as per the invention.

Figures 2 is a magnified portion of figure 1 focusing on a first embodiment of the damper.

Figures 3, 4 and 5 are 3D sections of alternative embodiments of said damper device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An engine injection equipment 10 arranged in an internal combustion engine has injectors adapted to spray, in the engine cylinders, fuel pressurised in a high pressure pump 12. Such HP pump 12 represented in section in figure 1 comprises a cambox 14 atop of which is arranged a pumping head 16. The cambox 14 has peripheral walls 18 defining an inner space S from which a bore 20 extends along a pumping axis Z toward an opening in an outer face where the pumping head 16 is arranged.

In use, fuel enters via a controlled inlet in a compression chamber 22 defined in said pumping head 16 where it is pressurised then expelled via a controlled outlet. The volume of said compression chamber 22 is alternatively varied by a piston 24 reciprocally moving in said bore 20, said piston 24 extending from said chamber 22 down to said inner space S wherein, a camshaft 26, not shown, rotating about a camshaft axis X perpendicular to the pumping axis Z, urges said piston 24 to reciprocally translate and perform a pumping cycle. The cambox 14 is filled with lubricating fuel subject to pressure variations generated by the piston's displacements, said variations being amortised by a damper device 28 arranged in a through aperture 30 provided in the cambox peripheral wall 18, substantially opposite the bore 20 in the example shown.

As visible on the non- limiting example of figure 1 and magnified in figure 2, said aperture 30 defines a peripheral cylindrical face 32 outwardly opening and inwardly extending toward an annular shoulder 34 which centrally opens in the cambox inner space S. The damper device 28 has a cylindrical shape adjusted to said aperture 30 and inserted therein until being in abutment against said shoulder 34 and there maintained in position by an elastic annular retaining ring 36 positioned in an annular groove 38 provided in said peripheral face 32.

The damper device 28 comprises a metal capsule 40 consisting of two thin springy disc- like diaphragms 42 with a gas filled inside. Each diaphragm 42 has a central area slightly offset from a peripheral annulus face and, to form the capsule, said two diaphragms are arranged facing one another, the annuli faces being welded together and, the central areas distant from one another defining therebetween a volume filled with gas pressurised to few bars.

The capsule 40 is positioned transverse to the general direction of the aperture 30 and there is held by its edge 44 inserted in a groove 46 provided in a capsule holder 48, that is wedged between the aperture shoulder 34 and a metallic plug 50 maintained by the retaining ring 36. A sealing O-ring 52 arranged between the plug 50 and the aperture peripheral face 32 assures sealing of the cambox 14.

The capsule holder 48 is a crenulated part having an annular base 54 on which several blocks 56 are formed and regularly spaced apart. Said holder 48 is moulded in rubber material, or the like, the base 54 having a rectangular cross- section and the blocks 56 rising in continuity of a base angular sector, thus forming a single cylindrical holder inner face 58 coaxial to a single cylindrical holder outer face 60. Furthermore, rising to the same height, the blocks 56 define together a common multi-portions holder upper face 62 that, in the aperture 30, is arranged in abutment against the shoulder 34.

The capsule holding groove 46 is provided in the block areas of said inner face 58, at a distance closer to the base 54 than from the upper face 62, therefore said groove 46 comprises, such as a dotted line, several sections interrupted by the slots.

Furthermore, in order to adjust the resiliency of the rubber holder 48, an insert 64 may be overmoulded in the base 54. On figure 5, a single annular insert 64 of rectangular cross-section is moulded in the base 54. In alternatives a plurality of inserts may be preferred, the number being chosen depending on the desired softness or rigidity of the holder. The insert was first thought to be made of plastic but, metallic inserts are also possible.

Said capsule holder 48 is arranged on an inner face 66 of the metallic plug. The interface 68 between the holder 48 and said plug inner face 66 may be a planar annular represented on the figures 4 and 5 or, may be a non-planar area, a stepped annulus being shown on figure 3. In this later case, the base cross- section is no longer a rectangle as previously mentioned but a polygon or, in a more general case, said holder under face is simply complementary adjusted to the plug inner face 66.

A non-planar interface 68 is preferred in the case of a rubber holder 48 bonded to the plug 50, or even moulded on said plug 50 thus, forming an integral single component adapted to receive the capsule 40.

In another case, where the holder 48 and the plug 50 are separate components, a planar interface 68 is preferred.

Thanks to said rubber holder 48, the damper device 28 is simplified and easily arranged in place.

At first the capsule 40 is positioned in the holder 48, said assembly being inserted in the aperture 30. Afterward, the aperture 30 is sealed by the plug 50 that is positioned and kept in place by the retaining ring 36.

In case of a holder 48 integral to the plug 50, the assembly capsule, holder and plug is inserted in the aperture 30 as one device kept in place by the retaining ring 36. LIST OF REFERENCES

X camshaft axis

Z pumping axis

S inner space

10 inj ection equipment

12 high pressure (HP) pump

14 cambox

16 pumping head

18 peripheral wall

20 bore

22 compression chamber

24 piston

26 camshaft

28 damper device

30 aperture

32 peripheral face

34 shoulder

36 retaining ring

38 groove of the retaining ring

40 capsule

42 diaphragm

44 edge of the capsule

46 groove for the capsule

48 capsule holder

50 plug

52 O-ring

54 base

56 blocks

58 holder inner face

60 holder outer face

62 holder upper face

64 insert

66 inner face of the plug

68 holder to plug interface

Claims

CLAIMS:

1. Damper device (28) adapted to be arranged in an aperture (30) provided through a peripheral wall (18) of a cambox (14) of a high pressure fuel pump (12) in order to attenuate low pressure fluctuations occurring in use, in said cambox (14), said damper device (28) comprising a damper capsule (40) held in a capsule holder (48) maintained in position in said aperture (30) by a metallic plug (50) adapted to seal said aperture (30) wherein, said capsule holder (48) is made of rubber material.

2. Damper device (28) as claimed in the preceding claim wherein said damper capsule (40) comprises pressurised gas captured between two diaphragms (42) arranged against each other and bounded together by their circular edge thus forming the capsule edge (44), the capsule holder (48) having an annular shape defining an inner annular face (58) surrounding an inner space in which said capsule (40) is arranged, the capsule edge (44) being inserted in an annular groove (46) provided in said inner annular face (58).

3. Damper device (28) as claimed in claim 2 said annular holder (48) is crenulated forming a plurality of rubber blocks (56) rising over a common annular base (54).

4. Damper device (28) as claimed in any of the claims 2 or 3 wherein the capsule holder (48) further comprises at least one plastic insert (64) overmoulded in the rubber material.

5. Damper device (28) as claimed in claim 4 wherein said plastic insert (64) is a closed annulus.

6. Damper device (28) as claimed in any of the preceding claims wherein the capsule holder (48) is integrally bounded to the metallic plug (50).

7. Fuel pump (12) having a cambox (14) in which, in use, a camshaft rotates, imparting reciprocal displacements to a piston (24), an aperture (30) being provided through the peripheral wall (18) of said cambox, a damper device (28) as claimed in any of the preceding claims being arranged in said aperture (30).

8. Fuel pump (12) as claimed in claim 7 wherein said aperture (30) defines a peripheral face (32) and a shoulder face (34), the damper device (28) being arranged so the capsule holder (48) abuts against said shoulder (34), the damper capsule (40) being substantially transverse to the aperture (30).