EP2137401A1

EP2137401A1 - High-pressure pump for delivering fuel with an improved design of the bearing arrangement for the support of the cam shaft

Info

Publication number: EP2137401A1
Application number: EP08701674A
Authority: EP
Inventors: Gerhard Meier; Armin Merz; Andreas Dutt
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2007-03-16
Filing date: 2008-01-25
Publication date: 2009-12-30
Also published as: US20100163005A1; DE102007012704A1; CN101646860A; WO2008113623A1; CN101646860B; JP2010520965A

Abstract

The present invention relates to a high-pressure pump (1), particularly for delivering fuel for a common rail fuel injection system, comprising a pump body (2), in which at least one cam drive (3) having a cam shaft (4) is received, wherein said cam shaft is pivotally supported about a cam shaft axis (6) in the pump body (2) and/or in a flange body (5) by means of at least one bearing arrangement, and wherein the bearing arrangement comprises a radial bearing bush (7) extending in the direction of the cam shaft axis (6), and an axial bearing disk (8), which is integrally formed on the radial bearing bush (7) on an end, and/or is connected to the same, wherein the axial bearing disk (8) extends in a radial extension direction (9) of <90° relative to the cam shaft axis (6) in the non-installed state, wherein the radial extension direction (9) is directed toward the radial bearing bush (7) and can be brought into an axial bearing plane (10) extending at an angle of 90º to the cam shaft axis (6) in the installed state by means of elastic deformation of the axial bearing disk (8).

Description

5 description

title

High pressure pump for delivering fuel with an improved design of the bearing assembly for supporting the camshaft

L O

The present invention relates to a high pressure pump for delivering fuel for a common rail fuel injection system according to the closer defined in the preamble of claim.

L 5 state of the art

High-pressure pumps for conveying fuel of the type of interest here are preferably formed with a cam drive, so that a camshaft is rotatably mounted in the pump body or in a flange body introduced into it. The camshaft

During operation, the high-pressure pump rotates about a camshaft axis and displaces one

Tappet unit in a lifting movement, which cooperates with a valve unit for conveying the fuel. Due to the high operating pressures of a common rail fuel injection system, high forces act on the camshaft via the cam drive, which is guided by a slide bearing arranged on the left and on the right side by the cam drive

5, the sliding bearings comprise a radial bearing bush for receiving radial forces, wherein an axial bearing disc is provided, which receives the forces in the direction of the camshaft axis. The camshaft is axially supported either in both directions of the camshaft axis with an axial bearing disc, wherein a structure with a single axial bearing can be provided. The radial bearing bush and the thrust washer

30 are formed as a single component, wherein depending on the structural design, the thrust washer and the radial bearing bush can be made in one piece and of uniform material or the thrust bearing disc is joined end to the radial bearing bushing. The connection of the thrust washer with the Radial bearing bush can be made cohesively or positively, preferably a welded joint is used.

It should be noted that the prior art also provides high pressure pumps, in which the 5 Axiallagerscheibe and the radial bearing bush are installed separately from each other in the housing. The fixation of the thrust washer is realized with dowel pins, this additional components and additional assembly operations are necessary, and therefore a unit of thrust washer and radial bearing bushing is preferred.

L 0 With such bearings of the camshaft in a high-pressure pump, the problem arises that the flat bearing of the thrust washer is not guaranteed to the plan contact surface in the pump body, since elastic deformations of the thrust washer can not be maintained at a considerable axial load of the axial bearing of the camshaft. This can lead to a very high load on the weld between the thrust washer

L 5 and the radial bearing bushing come so that they can fail. The damage result is a fracture of the weld between the thrust washer and the radial bearing bush, so that this leads to failure of the high-pressure pump. A fracture of the weld occurs in particular when the thrust washer is not flush with the plan contact surface in the pump body, so that under unfavorable loads voltage peaks and maximum

_ 0 surface pressures between thrust washer and face contact surface occur, the one

Overload and thus cause a fracture of the weld.

It is therefore the object of the present invention to provide a high-pressure pump for conveying fuel, which has an improved bearing arrangement for supporting the camshaft within the pump body.

This object is achieved on the basis of a high-pressure pump for conveying fuel according to the preamble of claim 1 in conjunction with its characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that extends the axial bearing disc in the non-installed state in a radial direction of extent of <90 ° relative to the camshaft axis, wherein the radial direction of extent to the radial bearing bushing points and in the installed state by means of an elastic deformation of the Axiallagerscheibe in a 90 ° to the camshaft axis extending thrust bearing plane can be brought.

The invention is based on the idea that the thrust washer by the inventive geometric design in the installed state in the region of

Weld produces a state of stress, in which a breakage of the weld does not occur. By targeted hiring the thrust washer can be made sure after joining the unit from thrust washer and radial bearing bush that the thrust washer rests securely against the plan contact surface on the pump body and a break in the weld L 0 is avoided. The deformation of the thrust washer from the radial direction of extent

<90 ° into the plane axial bearing plane takes place by an elastic deformation. In this case, only the spring action of the thrust washer is exploited, so that it rests both radially inwardly and radially outwardly flat on the plan contact surface.

Advantageously, the pump body has a plan contact surface, which is brought to the required accuracy by a machining operation, so that the axial bearing washer can lie flush against it when installed.

Advantageously, the radial direction of extension of the axial bearing disc in the non-0 installed state includes an angle to the camshaft axis of 80 ° - 89.99 ° and preferably from

86 ° -89.9 °. It is preferable to choose an angle close to 90 ° in order to minimize the stress on the weld by the elastic bending of the axial bearing disk in the installed state. In this case, an angle of 89 ° is particularly advantageous, wherein the angle is also dependent on the thickness of the thrust washer. The radial bearing bushing and the _ 5 thrust washer have a multi-component structure, so that a steel jacket the

Formed basic shape of the bearing bush or the thrust washer, and as a sliding surface for forming the sliding bearing a PEEK material or a carbon fiber reinforced material is introduced into the steel shell. However, the elastic bending of the thrust washer is limited to the steel shell, wherein the weld connects the respective steel components of the 30 Axiallagerscheibe and the radial bearing bushing. Thus, it can be assumed that in a thicker design of the steel component, an almost right angle is preferable, with a thinner design of the steel component may be a greater deviation from a right angle provided because the bending forces are also lower due to the lower stiffness , - A -

For structural reasons, it is of particular advantage that the radial bearing bush is pressed into a bearing bore introduced in the pump body and / or in the flange body. For assembly reasons, a flange body is provided, which also receives the bearing of the camshaft 5. This is a storage in the pump body itself and another storage in the flange. When mounting the high-pressure pump, a first bearing is first pressed into the pump body, so that then the camshaft can be added to the storage. Subsequently, a second bearing is pressed into the flange body, which finally used in the pump body and bolted to it

L becomes 0. Thus, a mountable and removable bearing assembly of the camshaft is provided, wherein a first bearing in the pump body and a second bearing is provided in the flange body. Pressing the radial bearing bush into the corresponding bore in the pump body or in the flange body offers a particularly easy joining possibility, wherein it must be ensured that the pressing force of the radial bearing bush in

L 5, the bearing bore must be sufficiently large to overcome the spring force in the thrust washer, and to ensure retention of the thrust washer on the plan contact surface, so that due to the spring action of the thrust washer, the radial bearing bush can not automatically withdraw from the bearing bore. However, other joining options are also possible, so that a clearance between the radial bearing bush and the

Bearing bore can be possible, and the axial fixation of the radial bearing bush or the

Axiallagerscheibe done by means of additional elements.

Advantageously, the surface pressure between the thrust washer and the face abutment surface over the radial width of the thrust washer has a uniform distribution

_ 5 on. Here, the angle between the extension direction of the thrust washer and the

Camshaft axis are chosen so that from the inside of the thrust washer to the radial outside there is a uniform surface pressure. The bending moment over the radius of the axial bearing disc decreases uniformly towards the outside, so that a plane axial bearing plane is formed when installed.

30

Furthermore, it is advantageous that the transition between the plan contact surface and the bearing bore in the pump body includes a chamfer. The formation of the chamfer can of course also be provided in the flange, so that in the throat between the thrust washer and the radial bearing bush, the weld a corresponding Can take space, so that the chamfer releases this space. In addition, the surface pressure between the plan contact surface and the thrust washer does not begin immediately radially on the inside in the axial bearing disk, but only after the end of the phase in the radial direction. This results in an advantageous geometric design and an improved 5 voltage introduction into the weld.

The uniform stress distribution also applies to the surface pressure between the thrust washer and the plan run of the camshaft, so that here also advantageously a uniform distribution of surface pressure over the radial width of the

L 0 thrust washer is present. This also relieves the weld between the thrust washer and the radial bearing bushing.

Further, measures improving the invention will be described below together with the description of a preferred embodiment of the invention with reference to the figures closer L 5.

embodiment

It shows: 20

1 is a cross-sectional side view of a high-pressure pump with a camshaft which is rotatably received within the pump body by means of a left-side and a right-side radial bearing bush and at least one thrust bearing bushing;

FIG. 2 shows a cross-sectional view of a unit made of a radial bearing bush and a thrust bearing washer welded to it in the uninstalled state; FIG. and

Fig. 3, the unit of radial bearing bush and the thrust bearing in a built-in state in the pump body. 30

The high-pressure pump 1 shown in FIG. 1 comprises a pump body 2, in which a camshaft 4 is rotatably mounted in the direction of a camshaft axis 6. The camshaft 4 comprises a cam drive 3, which sets a plunger unit 16 in a stroke movement, so that it can cooperate with a valve unit 17 to promote the Fuel effect. The Lagerang the camshaft 4 via two bearing arrangements, so that a left side arranged by the cam gear first radial bearing bushing 7 a is inserted within a flange 5, and a second radial bearing bush 7b is inserted into the right side of the pump body 2 itself. This is 5 both left and right side of the cam drive 3 a radial bearing, on the left side Axiallagerscheibe 8 is provided, which is welded to the radial bearing bushing 7a. The thrust washer 8 serves to receive forces acting axially in the direction of the camshaft axis 6, which are introduced into the camshaft 4 either externally or through the cam drive. The thrust washer 8 is located on the flange 5, L 0 wherein the radial bearing bushing 7 and the thrust bearing 8 is pressed into the flange 5. Further, the radial bearing bush 7b is press-fitted into the pump body 2, so that the respective radial bearing bushes 7a and 7b are axially fixed.

FIG. 2 shows a view of a bearing unit in a non-installed state, which L 5 comprises at least one radial bearing bush 7 and an axial bearing disk 8. The

Axial bearing washer 8 is connected by a peripheral weld 12 with the radial bearing bushing 7. According to the invention, the axial bearing disc has a radial extension direction 9, which assumes a value of <90 ° to the camshaft axis 6. The employment of the thrust washer 8 is uniform on the circumference, so that regardless of the circumferential direction, the radial direction of extent 9 the same angle <90 ° to

Camshaft axis 6 assumes. The thrust washer 8 is connected via the weld 12 with the radial bearing bushing 7, wherein the weld 12 is provided on the full circumference of the bearing assembly.

5 shows FIG. 3 shows the bearing arrangement according to FIG. 2 in a built-in in the pump body 2

Status. For installation, the radial bearing bushing 7 is pressed into the bearing bore 13 so that the axial bearing disk 8 rests flat against the planar contact surface 11 in the pump body 2. Thus, an elastic deformation of the thrust bearing 8 is caused so that it rests flat on the plan contact surface 11 over the entire radius from the inside to the outside radially.

Thus, the weld 12 is relieved, so that no unfavorable voltage peaks in the

Weld seam occur, and a breakage of the weld is avoided. The transition of the plan contact surface 11 to the bearing drilling 13 know a chamfer 14, so that the beginning of the flat contact of the thrust washer 8 takes place on the plan contact surface 11 only at a radius which is greater than the radius of the bearing bore 13. According to the invention Arrangement ensures that the thrust washer 8 provides a total of a flat contact surface for the camshaft to cause a uniform distribution of the surface pressure both between the camshaft and the thrust washer 8 and between the thrust washer 8 and the plan contact surface 11 in the pump body 2. 5

The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use. L O

Claims

5 claims

1. High-pressure pump (1), in particular for conveying fuel for a common rail fuel injection system, comprising a pump body (2) in which at least one cam drive (3) with a camshaft (4) is accommodated, said

L 0 by means of at least one bearing assembly in the pump body (2) and / or in a

Flange body (5) rotatably mounted about a camshaft axis (6) is mounted, and wherein the bearing assembly comprises a in the direction of the camshaft axis (6) extending radial bearing bushing (7) and a thrust washer (8), which end formed on the radial bearing bushing (7) and / or connected to it,

L 5 characterized in that the axial bearing disc (8) in the non-installed state in a radial extension direction (9) of <90 ° relative to the camshaft axis (6), wherein the radial extension direction (9) to the radial bearing bushing (7) points out and in the installed state by means of an elastic deformation of the thrust washer (8) in a 90 ° to the camshaft axis (6) extending thrust bearing plane (10) can be brought.

- 0

2. High-pressure pump (1) according to claim 1, characterized in that the pump body (2) has a plan contact surface (11) on which the thrust washer (8) is brought into the installed state plan to the plant.

3. High-pressure pump (1) according to claim 1 or 2, characterized in that the radial extension direction (9) of the axial bearing disc (8) in the non-installed state an angle (15) to the camshaft axis (6) of 80 ° to 89.99 ° and preferably from 86 ° to 89.9 °.

30 4. High-pressure pump (1) according to one of claims 1 to 3, characterized in that the axial bearing disc (8) by means of a weld (12) to the radial bearing bush (7) is welded.

5. High-pressure pump (1) according to one of the preceding claims, characterized in that the radial bearing bush (7) in a pump body (2) and / or in the flange (5) introduced bearing bore (13) is pressed.

5. High-pressure pump (1) according to one of the preceding claims, characterized in that the surface pressure between the thrust washer (8) and the flat contact surface (11) over the radial width of the axial bearing disc (8) has a uniform distribution.

L O 7. High-pressure pump (1) according to any one of the preceding claims, characterized in that the transition between the plan contact surface (11) and the bearing bore (13) in the pump body (2) comprises a chamfer (14).

8. High-pressure pump (1) according to one of the preceding claims,

L 5 characterized in that during the plan start of the camshaft (4) between this and the

Axiallagerscheibe (8) over the radial extent of the thrust washer (8) uniform surface pressure is present to relieve the weld (12).