GB2552653A

GB2552653A - Diesel fuel injection pumps assembly

Info

Publication number: GB2552653A
Application number: GB1613062.7A
Authority: GB
Inventors: Gilbert Barker Barrie
Original assignee: Delphi International Operations Luxembourg SARL
Current assignee: Delphi International Operations Luxembourg SARL
Priority date: 2016-07-28
Filing date: 2016-07-28
Publication date: 2018-02-07
Also published as: GB201613062D0

Abstract

A diesel fuel injection pumps assembly comprises a cambox to which are fixed a high pressure pumping head and a transfer pump. The arrangement is characterised by a means for coupling 52 in rotation a camshaft 20 to a driveshaft 50 of a transfer pump while accommodating slight misalignment of a first camshaft axis X1 and a second driveshaft axis X2. The coupling means comprises a pin 64 having a curved extremity 66, said pin extending from the camshaft along a third axis X3 parallel and offset to the first axis and, a tang 54 fixed to the driveshaft and comprising a peripheral ruled face 60 which directrix are aligned with the second axis. The coupling is designed to overcome excessive wear that would otherwise be present due to the misalignment caused by manufacturing tolerances and mechanical imperfections of the assembly. The curved extremity of the pin may contact the ruled face in a single contact area and may be spherical.

Description

(54) Title of the Invention: Diesel fuel injection pumps assembly Abstract Title: Diesel fuel injection pump coupling assembly (57) A diesel fuel injection pumps assembly comprises a cambox to which are fixed a high pressure pumping head and a transfer pump. The arrangement is characterised by a means for coupling 52 in rotation a camshaft 20 to a driveshaft 50 of a transfer pump while accommodating slight misalignment of a first camshaft axis X1 and a second driveshaft axis X2. The coupling means comprises a pin 64 having a curved extremity 66, said pin extending from the camshaft along a third axis X3 parallel and offset to the first axis and, a tang 54 fixed to the driveshaft and comprising a peripheral ruled face 60 which directrix are aligned with the second axis.

The coupling is designed to overcome excessive wear that would otherwise be present due to the misalignment caused by manufacturing tolerances and mechanical imperfections of the assembly.

The curved extremity of the pin may contact the ruled face in a single contact area and may be spherical.

FIG. 2

FIG

2/2

I

CM

FIG

X

Diesel fuel injection pumps assembly

TECHNICAL FIELD

The present invention relates to a diesel fuel injection pump assembly and more particularly to a means for coupling arranged between a camshaft and a driveshaft of a transfer pump.

BACKGROUND OF THE INVENTION

In diesel fuel injection assembly, a high pressure pump and a transfer pump are fixedly arranged on a the body of a cambox. Within the cambox a camshaft rotatable about a first axis imparts translations to a piston of the high pressure pump and also rotation about a second axis to the driveshaft of a transfer pump.

To position the transfer pump relative to the cambox and align the first and second axes, a cylindrical male face of the transfer pump registers in a complementary cylindrical female face of the cambox. To transmit the rotation the pump assembly is provided with a coupling means comprising a cylindrical pin fixed to the camshaft and a tang, or drive flange, fixed to the driveshaft. The pin is parallel and offset to the first axis and it extends from the camshaft and it is in contact against a face of the tang which directrix are aligned to the second axis.

Because of functional tolerances and other mechanical minor imperfections of the assembly, the first and second axes are not perfectly aligned generating, in use, excessive wear within said coupling means.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a diesel fuel injection pumps assembly comprising a cambox having a body on which are fixed a high pressure pumping head and a transfer pump and, in which a camshaft is arranged rotatable about a first axis, said camshaft transmitting in use, reciprocal translations to a piston of the high pressure pumping head and, rotation to a driveshaft of the transfer pump arranged to rotate about a second axis aligned to the first axis.

Advantageously, the diesel fuel injection pumps assembly further comprises means for coupling in rotation the camshaft to the driveshaft while accommodating slight misalignment of the first and the second axes, said coupling means comprising a pin having a curved extremity, said pin extending from the camshaft along a third axis parallel and offset to the first axis and, a tang fixed to the driveshaft and comprising a peripheral ruled face which directrix are aligned with the second axis.

Also, the curved extremity contacts the ruled face in single contact area. Also, in a particular embodiment, the curved extremity is spherical.

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 an axial section of a diesel fuel pump assembly as per the invention.

Figure 2 is a 3D representation of a coupling means used in the pump assembly of figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In reference to the figures is now described a high pressure diesel fuel pump assembly 10 comprising a high pressure pump 12 and a transfer pump 14, both pumps being fixed to a cambox 16. Said cambox 16 has a body 18 defining an inner space in which a camshaft 20 is adapted to rotate about a first axis XI between a front bearing 22, on the right of figure 1, aligned with a rear bearing 24 on the left of figure 1. In the embodiment presented, said camshaft 20 is provided with two cams 26 arranged between said the bearings 22, 24 and each cam impart, in use, reciprocal displacements to a piston 28. On the exemplary embodiment of figure 1, the camshaft has two cams, alternatively, other cambox are known and made with another number of cam, either one, three or more. At a lower end, the piston 28 is provided with a cam follower 30 that cooperates with the cam 26 and, an opposite upper end of the piston partly defines, within a pumping head 32, a compression chamber 34 within which fuel is pressurized prior to be delivered to a high pressure rail and then to fuel injectors, not represented. While the front end 36 of the camshaft, right of the figure, is adapted to receive a pulley, or other transmission means for driving the camshaft in rotation, the opposite rear end 38, left of the figure, is adapted to transfer the rotational movement to the transfer pump 14.

The transfer pump 14 can be a gear pump or a vane pump or any other type but, whatever type of pump is, it has a body 40 having a front face 42 adjusted in abutment against a rear face 44 of the cambox body 18. Axial X positioning is ensured by a cylindrical male face 46 of the body of the transfer pump protruding from said front face 42 and registering in a complementary cylindrical female face 48 of the cambox body 18. The transfer pump 14 is provided with a driveshaft 50 adapted to rotate about a second axis X2, that is theoretically aligned to the first axis XI, and that drives in rotation the internal mechanism of the transfer pump

14.

The camshaft 20 and the driveshaft 50 are engaged via means for coupling 52 now described in reference to figure 2.

At the extremity of the driveshaft 50 is fixed a tang 54, also identified as a drive flange, having a cylindrical central portion 56 surrounding said driveshaft and, a pair of opposed radial extensions 58 each having a slight V-shape pointing on the second axis X2. The tang 54 defines a peripheral face 60 surrounding said central portion and the extensions, said peripheral face 60 being a ruled face with directrix along said second axis X2. At the intersections of said central portion 56 and said extensions 58, the peripheral face 60 changes curvature to an inwardshape such as a quarter of female cylinder 62 in which engages a profiled pin 64 fixed to the rear end 38 of the camshaft. From said rear end 38, the profiled pin 64 extends from the rear end face 38 of the camshaft along a third axis X3 parallel and offset to the first axis XI, toward a profiled end 64 shaped with a spherical face 66. Said profiled end 66 is in contact against said quarter female cylinder 62 and, said spherical face 66 advantageously limits to a single area the pin-to-tang contact, single area that accommodates any minor misalignment between the axes XI, X2, X3. In alternative embodiments, the end shape of the pin could be ovoid, oval or any other shape reducing said pin-to-tang contact to a single area.

Also, in another alternative, to divide the force transmitted by the pin, the rear end 38 of the camshaft could be provided with two diametrically opposed pin 64.

In further embodiments, the tang 54 could have more than two extensions 58, three, four, or more... and the rear end 38 of the camshaft be provided with the same number of profiled pin 64.

Also, the tang 54 is described and represented having said two opposed Vshaped extensions 58, but any other shape of the tang 54 such as a simple rectangle providing to the profiled pin a plan abutment face would also be suitable.

LIST OF REFERENCES

XI first axis

X2 second axis

X3 third axis diesel fuel pump assembly 12 high pressure pump transfer pump cambox body of the cambox camshaft front bearing rear bearing cam piston cam follower pumping head compression chamber front end of the camshaft rear end of the camshaft body of the transfer pump front face of the body of the transfer pump rear face of the body of the cambox cylindrical male face cylindrical female face driveshaft of the tranfert pump coupling means tang - drive flange central portion extension peripheral face of the tang

1/4 female cylinder pin spherical end of the pin

Claims

1. Diesel fuel injection pumps assembly (10) comprising a cambox (16) having a body (18) on which are fixed a high pressure pumping head (32) and a

5 transfer pump (14) and, in which a camshaft (20) is arranged rotatable about a first axis (XI), said camshaft (20) transmitting in use, reciprocal translations to a piston (28) of the high pressure pumping head (32) and, rotation to a driveshaft (50) of the transfer pump (14) arranged to rotate about a second axis (X2) aligned to the first axis (XI),

10 characterized in that the diesel fuel injection pumps assembly (10) further comprises means for coupling (52) in rotation the camshaft (20) to the driveshaft (50) while accommodating slight misalignment of the first (XI) and the second (X2) axes, said coupling means (52) comprising a pin (64) having a curved extremity, said

15 pin (64) extending from the camshaft along a third axis (X3) parallel and offset to the first axis (XI) and, a tang (54) fixed to the driveshaft (50) and comprising a peripheral ruled face (60) which directrix are aligned with the second axis (X2).

2. Diesel fuel injection pumps assembly (10) as claimed in the preceding

20 claim wherein the curved extremity (66) contacts the ruled face (60) in single contact area.

3. Diesel fuel injection pumps assembly (10) as claimed in the preceding claim wherein the curved extremity (66) is spherical.

Intellectual

Property

Office

Application No: GB 1613062.7 Examiner: Nicholas Wigley