GB2567849A

GB2567849A - High pressure valve

Info

Publication number: GB2567849A
Application number: GB1717649.6A
Authority: GB
Inventors: Mehmet Tansug Onur
Original assignee: Delphi International Operations Luxembourg SARL
Current assignee: Delphi International Operations Luxembourg SARL
Priority date: 2017-10-26
Filing date: 2017-10-26
Publication date: 2019-05-01
Also published as: GB201717649D0

Abstract

A valve adapted to be arranged on the high pressure common rail of diesel injection equipment is disclosed. The valve comprises a body in which a valve member 12 is guided. The needle 12 cooperates with a valve seat 8 that has a female conical sloped seating face 6. The tip of the valve member 12 abuts sealingly against the seat 8. The valve member tip may be in the form of several male conical faces, with the sealing contact between the tip and the valve seat occurring at the intersection of two of these faces. Means 31 for guiding the valve member may also be present. This may take the form of a tubular member extending from the seat member.

Description

HIGH PRESSURE VALVE

TECHNICAL FIELD

The present invention relates to a valve suitable for being arranged on a diesel common rail in order to regulate the inner pressure of the rail. The invention relates more precisely to the means to close a spill orifice.

BACKGROUND OF THE INVENTION

A fuel injection equipment of an internal combustion engine is provided with a high pressure (HP) reservoir, known as a common rail, that receives HP fuel, retains and delivers said fuel to a plurality of fuel injectors. To prevent the rail inner pressure to exceed a predetermined threshold, a HP valve is arranged on the common rail to close or to open a return orifice for preventing or enabling fuel to exit the rail.

A HP valve 1 of the prior art is shown on figures 1 and 2 where a pusher member 2 reciprocates along a longitudinal axis X in a guiding bore 3 of the valve body 4, urges a ball 5 against a female conical seat face 6 defined around the opening of a return orifice 7 centrally drilled in a seat member 8 fixed to said valve body 4. The HP valve lisa controlled electrovalve wherein an actuator drives said pusher as a function of command signals received from a command unit. Mechanical valves are also know wherein the pusher is pushed by a coil spring toward a closed position of the return orifice.

The closing means of the valve 1, particularly shown on figure 2, comprises the end of the pusher 2 cooperating with the ball 5, said pusher end being provided with a small concave calotte 9 within which the ball 5 stays.

Despite this concave geometry, when the pusher 2 retracts to open the return orifice the ball 5 becomes free to move within a small space defined between said calotte 9 and the conical seat 6. Since the ball 5 is directly impacted by the HP fuel exiting the rail, the ball 5 bounces against the seat 6 and the calotte 9 generating noise and hammering said faces, potentially causing wear on the seat. This instability also generates undesirable pressure oscillations.

To mitigate said problems the design of the calotte and its manufacturing are optimised ensuring a coaxial X alignment of the pusher 2 and of the conical seat 6 as perfect as possible. For instance, the functional clearance between the pusher 2 and the guiding bore 3 ranges between 25pm and 70pm but, even with a perfect alignment at high flow velocities turbulences in the flow will exert forces on the ball and make it unstable.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a valve of a diesel injection equipment adapted to be arrange on a high pressure common rail, said valve comprising a body in which a valve member is guided along a longitudinal axis and cooperates with a valve seat member to open or to close a fluid communication. The valve seat member is a thick disc-like member crimped, or press-fitted or any other fixing means, in a complementary recess of the body and having an inner face oriented toward the valve member opposed to an outer face and, being provided with an axial through orifice for fuel in excess in the rail to flow off the rail. The inner opening of said orifice on the inner face defines a female conical seat face.

The valve member guided in the body has a tip extremity defining a closing face complementary adjusted to sealingly abut said female sloped seating face.

Said closing face may define a second male conical face.

Said tip extremity of the valve member may further define a third male conical face adjacent the first male conical face.

The first and the second male conical faces intersect on a circular line.

In closed position of said a fluid communication, the tip end of the valve member abuts the female sloped seating face along said circular line.

The cone angle of the second closing face is smaller than cone angle of the seat face and, the cone angle of the third closing face is bigger than cone angle of the seating face.

The nominal difference between said angle of the male conical faces and the angle of the female conical face may be comprised between 1 and 2 degrees.

The valve member is guided in a bore defining therebetween a clearance that may range between 40 pm and 90 pm.

The valve member may be made out of High Speed Steel.

The valve seat member may further be provided with a guiding means for guiding the valve member in the vicinity of seat face.

Said guiding means is a tubular member axially extending from the inner face of the seat member, the tubular member having an inner diameter adjusted to guide the valve member.

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 HP valve of the prior.

Figure 2 is a detail of a valve seat of the valve of figure 1.

Figure 3 is a detail of a valve seat of a valve as per the invention.

Figure 4 is a detail of another embodiment of the valve seat as per the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A HP valve 1 shown on figures 1 and 2 and previously presented in the prior art serves now as a basis to describe the invention particularly shown on figure 3 where the valve 1 is no longer provided with a pusher 2 and ball 5 but with an integrated needle valve member 12 having a tip end 14 cooperating directly with the female seat face 6 of the seat member 8.

The return orifice 7 is centrally drilled through the cylindrical base of the seat member 8 and it defines on the needle side an opening comprising said female conical valve face 6 having a seat angle A6, measured between the longitudinal axis X and a generatrix of said conical face 6 and enlarging from a lower boundary 17 that is a circle of diameter D17 of intersection with the orifice 7 and j oining an upper boundary 18 that is a circle of diameter D18 of intersection with a second conical face 16 further enlarging the opening and joining the inner face of the seat member 8, said second conical face 16 having an angle Al 6 larger than the seat angle A6.

The needle valve member 12 has an elongated cylindrical core 13, axially guided in the guiding bore 3 with an functional clearance C enlarged and ranging between 40pm and 90pm, and said male tip end 14 cooperating with the female seat face 6. Said tip end 14 narrows from the core 13 down to the very end point of the needle defining a first male conical face 21, having a first angle A21, a second male conical face 22 having a second angle A22, a third male conical face 23 having a third angle A23 and a final fourth male conical face 24 having a fourth angle A24 and an apex on said very end point 15 of the needle. In alternatives not presented, the final fourth face can take another shape than the cone shown such flat face or a rounded face.

The first 21 and second 22 male conical faces intersect along an upper circle 27 of diameter D27, the second 22 and the third 23 male conical faces intersect along a middle circle 28 of diameter D28 and, the third 23 and fourth 24 male conical faces intersect along a lower circle 29 of diameter D29.

As shown on figure 3, the tip end 14 of needle engages in the seat member and sealingly cooperate with the seat face 6. To achieve this the following design relationship are selected:

D18 > D27 > D28 > D29 and A16 > A23 > A6 > A22 > A21

More precisely, a key design characteristic is that said tip end and said seat face are sealingly contacting along the middle circle 28 and, to achieve this key design characteristic the angle A6 of the female seat face has a nominal dimension that is approximately 1.5° larger than the angle A22 of the second male conical face 22 and, 1.5° smaller than the angle A23 of the third male conical angle 23.

Said dimensional proximity of the angles assures that the sealing middle circle 28 represents a small protrusion from the tip end 14 faces entering first in contact against the seat face 6 when the needle closes.

In a preferred example the angles chosen are:

A23 =	= 71.5°	+/- 0.5°
A6 =	= 70.0°	+/- 0.5°
A22 =	= 68.5°	+/- 0.5°

Furthermore, to confer to the needle 12 the necessary strength and durability the 100Cr6 steel used to make said needle 12 is replaced by “High Speed Steel” comprising additives of approximately 14% tungsten ; 4% chromium ; 0,6% vanadium.

In another alternative embodiment shown on figure 4 the seat member 8 is provided with a tubular guiding extension 31, coaxial to the orifice 7 and axially

X protruding inside the HP valve body 4 from the cylindrical base over a height H31 sufficient for the needle 12 to engage said tubular extension 31 and to be guided therein, the inner diameter D31 of the guiding extension and the diameter D13 of the core 13 of the needle being complementary and slidably adjusted with a functional clearance comprised between 3 gm and 7 pm. As shown, the conical faces 6, 16 of the opening of the orifice 7 define the bottom face of said tubular extension. Furthermore, to ensure evacuation of the fuel when the needle lifts and opens the orifice, the side wall of the tubular extension is provided with at least one radial through hole 32 (two being shown on the figure) establishing a fluid communication toward a return line.

Thanks to this guiding tubular extension, the needle 12 is axially X guided in the bore 3 and on close proximity to said sealing tip end 14, in the tubular extension 31. This arrangement ensuring proper sealing relation on said middle circle 28 abutting said seat face 6.

LIST OF REFERENCES

X	longitudinal axis
c	clearance
A6	angle
A16	angle
A21	angle
A22	angle
A23	angle
A24	angle
D17	diameter
D18	diameter
D27	diameter
D28	diameter
D29	diameter
1	HP valve
2	pusher
3	bore
4	body
5	ball
6	seat face
7	orifice
8	seat member

calotte needle valve member core of the needle tip end of the needle valve member end point of the needle second female conical face lower boundary upper boundary first male conical face second male conical face third male conical face fourth male conical face upper circle middle circle lower circle tubular guiding extension hole

Claims

CLAIMS:

1. Valve (1) of a diesel injection equipment adapted to be arrange on a high pressure common rail, said valve comprising a body (4) in which a valve member (12) is guided along a longitudinal axis (X) and cooperates with a valve seat member (8) to open or to close a fluid communication, said valve seat member being a thick disc-like member fixed in a complementary recess of the body and having, an inner face oriented toward the valve member opposed to an outer face and, being provided with an axial through orifice (7) for fuel in excess in the rail to flow off the rail, the inner opening of said orifice on the inner face defining a female conical seat face (6) and wherein, the valve member (12) guided in the body has a tip extremity (14) defining a closing face (21, 22, 23, 24) complementary adjusted to sealingly abut said female sloped seating face.

2. Valve (1) as claimed in the preceding claim wherein said closing face (21, 22, 23, 24) defines a second male conical face (22).

3. Valve (1) as claimed in claim 2 wherein said tip extremity of the valve member further defines a third male conical face (23) adjacent the first male conical face.

4. Valve (1) as claimed in claim 3 wherein the first and the second male conical faces intersect on a circular line (28).

5. Valve (1) as claimed in claim 4 wherein, in closed position of said a fluid communication, the tip end of the valve member abuts the female sloped seating face along said circular line (28).

6. Valve as claimed in claim 5 wherein the cone angle (A22) of the second closing face is smaller than cone angle (A6) of the seat face (6) and wherein, the cone angle of the third closing face (A23) is bigger than cone angle (A6) of the seating face.

7. Valve (1) as claimed in claim 7 wherein the nominal difference between said angle (A22, A23) of the male conical faces and the angle (A6) of the female conical face is comprised between 1 and 2 degrees.

8. Valve (1) as claimed as in any one of the preceding claims wherein the valve member (12) is guided in a bore (3) defining therebetween a clearance (C) ranging between 40pm and 90pm.

9. Valve (1) as claimed in any one of the preceding claims wherein the valve member (12) is made out of High Speed Steel.

10. Valve (1) as claimed in any one of the preceding claims wherein the valve seat member (8) is further provided with a guiding means (31) guiding the valve member (12) in the vicinity of seat face.

11. Valve (1) as claimed in claim 10 wherein said guiding means (31) is a tubular member axially extending from the inner face of the seat member, said tubular member having an inner diameter (D31) adjusted to guide the valve member (12).