DE102007012707A1 - High-pressure pump for conveying fuel with an improved lubricant supply in the camshaft bearing - Google Patents

Abstract

The present invention relates to a 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, by means of at least a radial bearing and at least one thrust body (5) having axial bearing is rotatably mounted, wherein the bearings are lubricated with a supplied lubricant and the lubricant by at least one between the startup body (5) and the pump body (2) introduced lubricating channel (6) can be fed ,

Description

The The present invention relates to a high pressure pump for delivery of fuel according to the im The preamble of claim 1 closer defined type.

State of the art

such High pressure pumps are used for common rail fuel injection systems used, which to promote of the fuel to a high pressure within the common rail are provided. Such high pressure pumps are with a cam drive formed, which comprises a camshaft having a cam portion having. On the Cam section rolls off a tapping element, so that a lifting movement is generated in the tapping element, which is transmitted to a plunger device. The ram device comprises a pump piston which cooperates with a valve unit, for the promotion of the fuel with the lifting movement of the pump piston to effect.

The Camshaft is in the pump body stored, wherein the bearing is preferably designed as a sliding bearing. Dependent on of the design of the high-pressure pump, the storage can also within a flange body be introduced, wherein the flange connected to the pump body is. The bearings are preferably plain bearings, so this formed from bearing bushes with a corresponding bearing material are. The bushings are located to the side of the cam section, so that optimum absorption of the introduced into the camshaft personnel is possible. For assembly reasons is the plain bearing, which is introduced in the pump body, with a slight smaller diameter formed as the plain bearing, which in the flange is introduced. In addition to the radial bearings and thrust bearings are the Camshaft required, the thrust bearing formed in the form of starter bodies are, and also act on the principle of a sliding bearing. The area for the plan start of the camshaft is preferably located laterally on the cam geometry, as these have a larger base circle diameter has, as the adjacently arranged cylindrical portions of Camshaft. For lubrication of the radial and thrust bearing is the Fuel itself used, which is inside the high pressure pump located. The area of the cam drive and thus the area of the Storage is filled with fuel, so this too Lubrication of the radial and axial plain bearings is available.

Of the Fuel gets to the lubrication of the thrust bearing and the radial bearing only about the bearing gap of the thrust bearing in the camps, so that the Lubricate the radial bearings by first passing the lubricant through the thrust bearing to get into the lubrication gap of the radial bearings.

at Such bearing arrangements often results in the problem that the Lubrication of radial bearings may be is not sufficient to ensure a fatigue life of the storage. The bad lubrication is due to the fact that the lubricant supply only about the thrust bearing takes place, so that due to the small lubrication gaps frequently little lubricant gets into the area of the radial bearing. Therefore it comes to an early Wear in particular the radial bearing, which can lead to failure of the high-pressure pump.

It Therefore, the object of the present invention, the supply of the Lubricant for the bearing of the camshaft within the pump body a To improve high-pressure pump.

Disclosure of the invention

These Task is starting from a high pressure pump for promotion of fuel according to the preamble of claim 1 in conjunction with its characterizing features solved. Advantageous developments of the invention are specified in the dependent claims.

The Invention includes the technical teaching that the lubricant by at least one between the start-up body and the pump body introduced Lubricating channel can be fed is.

The Invention is based on the idea of the supply of lubricant for lubrication of the radial bearing not over the gap in the thrust bearing itself to be done, but by separate lubrication channels, the between the starting body, which forms the thrust bearing, and the pump body / flange introduced are. On the outside, in the area around the starting body around is the pump body filled with fuel, so that it acts as a lubricant and through the lubrication channels radially externally enter, and radially inward towards the radial bearing stream can. As a result, the radial bearing is a larger amount of lubricant to disposal so that a full lubrication of the radial bearing also over a long Operating period and high radial and axial bearing forces ensured is. When the thrust bearing is inserted in the flange body, so extends the lubrication channel between the starter body and the flange body, so that the arrangement of the lubrication channel as well as between the starter body and the pump body is provided.

Advantageously, the radial bearing comprises a radial bearing bush, which is inserted in a bearing bore in the pump body and with the No Ckenwelle forms a sliding bearing assembly. The radial bearing bush can also be introduced in the flange body, wherein this comprises a metallic base body which comprises a synthetic insert forming the sliding bearing, which forms a particularly advantageous friction pairing with the camshaft. Therefore, the radial bearing bush is not made of the same material and in one piece, but may consist of several coaxially interconnected sleeve bodies made of different materials. However, it is also conceivable that, depending on the choice of material, the radial bearing is formed directly by the pump body or the flange body, which may include a possible surface coating.

It is advantageous that several lubrication channels are provided for lubrication of the radial bearing, which in associated lubrication openings between the start-up body and the radial bearing bushing open. The lubrication channels can on the circumference of the starter body or between the starting body and the pump body or the flange body be provided repeatedly and evenly distributed to the lubricant radially circumferentially supply from several points. This is an improved Lubricant supply to the radial bearing ensures, with even one Variety of small lubrication channels may be provided, which at regular intervals similar to each other a Hirth toothing are formed. The lubrication openings form the radially inner end of the lubrication channels between the start body and the pump body, from which the lubricant exits and into the radial bearing gap arrives.

A advantageous embodiment of the axial and radial bearing comprises a starter body and a Radial bearing bush, which together in one piece and / or material formed or cohesive or positive fit with each other, the connection between the startup element and the radial bearing bushing has interruptions in the circumferential direction, the lubrication holes form. The start-up body as well as the radial bearing bushing thus form a common bearing body, which cutting, forming or can be produced by molding technology. It must be ensured be that between the portion that forms the start body, and the portion of the radial bearing bush, the lubrication channels in lubrication ports lead, which as an interruption between the connection between the part of the starting body and the part of the radial bearing bush are formed. Is the starter body with the radial bearing bush connected by means of a joining method, the lubrication holes be executed in the form of breaks in the joints. For example, the thrust washer to the radial bearing bushing welded be, with the weld breaks has, and the interruptions occur at the points of the lubrication channels, allowing the lubricant through the lubrication channels and consequently through the interruptions can get into the interior of the camp.

A further advantageous embodiment of the Arrangement of the lubrication channels provides that these are introduced on the plan side in the starting body in the form of grooves are. An alternative embodiment of the Arrangement of the lubrication channels On the other hand, it provides for these in the form of grooves in the flat contact surface of the pump body or the flange body introduced are. It is also a combination of both embodiments of lubrication channels possible, so that the lubrication channels in the start body and in the plan contact surface of the pump body or the flange body either face or these circumferentially offset from each other to order the number of lubrication channels to increase. are the respective lubrication channels are superimposed, so it increases the cross section of the individual lubrication channels accordingly.

It is advantageous that the lubrication channels in the form of grooves in the End contact surface of the pump body are introduced. The pump body becomes preferably produced by means of a casting process, so that the lubrication channels already be provided in the mold of the pump body. Also by machining, the lubrication channels in the End contact surface are introduced, preferably using a milling method are applied can. Furthermore, can the lubrication channels by a stamping process, a punching process or in the casting itself in the plan contact surface of pump body be introduced, with the same process options Also possible for introducing the lubrication channels in the flange.

advantageous embodiments The cross-sectional geometry of the lubrication channels can be round, rectangular or trapezoidal Cross-sections include, wherein the round cross-section grooves in shape of semicircles. The size of the lubrication channels forming grooves must correspond to the thickness of the starter body, so this does not respect the required strength is weakened. Thus, it is advantageous to have several lubrication channels evenly distributed on the circumference to bring so that the plan system of the starter body regularly through the lubrication channels is interrupted. Therefore, the lubrication channels on the circumference of the axial or radial bearings complained to each other the same or irregularly arranged.

Furthermore, it is advantageous that the radial bearing bush on the end adjacent to the starting body on a radially inside mounted bevel has. The chamfer improves the entry of the lubricant into the lubricating gap between the radial bearing bushing and the camshaft, wherein the chamfer is attached to the inner end of the radial bearing bush, so that the lubrication channel ends radially inward in the starter body and the lubricating opening merges into the chamfer to prevent the entry of the Lubricant in the lubrication gap of the radial bearing beech easier.

to It is also improved by improving the lubricating effect of the radial bearing Advantage that the lubrication channels in the start body and / or in the plan contact surface in the pump body a pointing in the radial direction of the bearing linear or spiral extension have, with the twisting direction of the spiral extension opposite the direction of rotation of the camshaft points to an improved Entrance of the lubricant in the lubrication channels to create. Through the rotation the camshaft becomes the fuel that surrounds the camshaft as well in a rotational flow added. Assign the openings the lubrication channels against the flow direction of the fuel, so this is in an advantageous manner in the lubrication channels depressed or entering the fuel into the lubrication channels at least improved. As right and left running high pressure pumps can be used in the spiral Extension provided mutually aligned swirl directions of the lubrication channels be so for both Running directions of the camshaft either a first portion of the lubrication channels or a second portion of the lubrication channels in an improved manner with fuel is charged.

Further, the invention improving measures will be described below together with the description of a preferred embodiment of the invention with reference to the figures shown in more detail.

embodiment

It shows:

1 a cross-sectional view of a high-pressure pump with a bearing mounted by means of plain bearings camshaft;

2 a section of the sliding bearing within the pump body with an axial starting body and a radial bearing bush and at least one lubricating channel between the starting body and the pump body;

3 a further embodiment of the lubricating channels according to the invention between the starting body and the pump body;

4 a view of a start-up body, wherein on the left side linearly aligned lubrication channels and right side lubrication channels are shown with a spiral extension in a twisting direction;

5a a cross-sectional view of a section of a startup body having a rectangular cross section of a lubrication channel;

5b a section of a starting body with a trapezoidal cross-section of a lubricating channel; and

5c a view of a section of a start-up body with a round cross section of a lubrication channel.

In the 1 illustrated high-pressure pump 1 includes a pump body 2 through which a camshaft 4 extends through. The intake of the camshaft 4 takes place by means of a storage, for radial storage two radial bearing bushings 7a and 7b comprises, and for axial storage at least one starting body 5 includes. The camshaft 4 is both in the pump body 2 itself as well as in a flange body 9 stored, which in the pump body 2 introduced and screwed with this. The left radial bearing bush 7a as well as the start-up body 5 are in the flange body 9 recorded, with the right-side bearing, consisting of the radial bearing bushing 7b , in the pump body 2 is included. The bearings act with a cylindrical bearing portion of the camshaft 4 together, and form the arrangement of a respective sliding bearing. The bearings are left and right sides of the camshaft section 4 arranged that the cam shoot 3 forms. The cam shoot 3 acts with a tap element 10 together, which is designed as a role. The tapping element 10 displaces a ram unit 11 in a lifting movement, which with a valve unit 12 is operatively connected to promote the fuel to the desired pressure. The ram unit 11 and the valve unit 12 are in a cylinder head 13 taken, which with the pump body 2 is screwed. About the cam drive 3 and in particular via the contact of the tapping element 10 with the cam portion on the camshaft 4 is introduced into this one force, which by the promotion of the fuel from the ram unit 11 on the camshaft 4 is transmitted. The forces are transmitted by means of radial bearing bushings 7a and 7b recorded, in addition axial forces can arise, which by the starter body 5 be recorded. The axial forces can also be caused by external factors in the camshaft 4 are introduced, which from the direction of the pump body 2 outwardly extending portion of the camshaft 4 be initiated in this.

2 shows an enlarged section of the bearing assembly within the pump body 2 , wherein for receiving the axial forces a starting body 5 is provided, which has a contact surface 13 includes, against which the camshaft can start. Between the start-up body 5 and the pump body 2 is the lubrication channel according to the invention 6 shown, wherein a first lubrication channel 6 is shown in cross-section, and 90 ° offset from the first lubrication channel, a second lubrication channel 6 is shown, which can be seen from the direction of the lubricating opening. To form the radial bearing is in the pump body 2 a radial bearing bush 7 introduced, which with the starting body 5 either one-piece and of uniform material may be formed or connected to this material or form-fitting. The lubricant passes through the lubrication channel 6 in the lubrication gap between the radial bearing bush 7 and the camshaft so that improved lubrication of the radial bearing is ensured. To the inflow of the lubricant into the lubrication gap within the radial bearing bushing 7 to improve is between the lubrication channel 6 and the interior of the radial bearing bushing a chamfer 8th attached, which is designed in the form of a 45 ° bevel. The lubrication channels 6 are in the start body 5 introduced in the form of depressions, wherein according to the present embodiment on the circumference of the starting body 5 a total of four lubrication channels 6 are provided.

3 shows a further embodiment of the inventive solution for the lubrication of the radial bearing, wherein the lubrication channel 6 also between the starting body 5 and the pump body 2 is introduced. However, in this embodiment, the lubrication channel 6 in the plane contact surface of the pump body 2 introduced, and not in the starting body 5 , The lubricant can also in this embodiment by the lubrication channel 6 into the inside of the radial bearing bush 7 arrive, with the lubrication channel 6 in the form of a milled, stamped or cast groove inside the pump body 2 is trained.

4 shows various embodiments of the lubrication channel 6 within the startup body 5 or the pump body 2 , where left two lubrication channels 6a with a linear extension and right side two lubrication channels 6b are shown by way of example with a spiral extension.

The 5a to 5c show different cross-sectional geometries of the lubrication channels 6 which are inside the starting body 5 are introduced. 5a shows a rectangular cross section of a lubrication channel 6 . 5b shows a trapezoidal cross-section of a lubrication channel 6 and the 5 shows a circular or semicircular cross-section of the lubrication channel 6 , The lubrication channels 6 are opposite to the contact surface 13 in the starter body 5 brought in.

The present 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. It should be noted that the lubrication channels according to the invention both on the contact surface 13 opposite surface of the starting body 5 There is also the possibility that the lubrication channels 6 on the same side within the contact surface 13 are located. Furthermore, it is possible that both on the contact surface 13 as well as on the run-up surface 13 opposite surface in the starter body 5 lubrication channels 6 are introduced.

Claims (10)

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 received, which by means of at least one radial bearing and at least one of a starter body ( 5 ) is rotatably mounted, wherein the bearings are lubricated with a supplied lubricant, characterized in that the lubricant by at least one between the starter body ( 5 ) and the pump body ( 2 ) introduced lubricating channel ( 6 ) can be fed. High pressure pump ( 1 ) according to claim 1, characterized in that the radial bearing a radial bearing bush ( 7 ), which in a bearing bore in the pump body ( 2 ) is used and with the camshaft ( 4 ) forms a sliding bearing assembly. High pressure pump ( 1 ) according to claim 1 or 2, characterized in that for lubrication of the radial bearing a plurality of lubrication channels ( 6 ) are provided, which in lubrication openings between the starter body ( 5 ) and the radial bearing bush ( 7 ). High pressure pump ( 1 ) according to one of claims 1 to 3, characterized in that the starting body ( 5 ) and the radial bearing bushing ( 7 ) are formed in one piece and / or material of uniform or materially or positively connected with each other in connection, wherein the connection between the starting body ( 5 ) and the radial bearing bush ( 7 ) has interruptions in the circumferential direction, which form the lubrication openings. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the lubricating channels ( 6 ) on the plan side in the starter body ( 5 ) are introduced in the form of grooves. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the lubricating channels ( 6 ) in the form of grooves in the plane contact surface of the pump body ( 2 ) are introduced. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the lubrication channels ( 6 ) forming grooves have a round, a rectangular or a trapezoidal cross-section. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the lubricating channels ( 6 ) are arranged equidistantly spaced from each other on the circumference of the axial or radial bearing. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the radial bearing bush ( 7 ) on to the starter body ( 5 ) adjacent end a radially inwardly introduced bevel ( 8th ) having. High pressure pump ( 1 ) according to one of the preceding claims, characterized in that the lubricating channels ( 6 ) in the starter body ( 5 ) and / or in the plan contact surface in the pump body ( 2 ) have a pointing in the radial direction of the bearing linear or spiral extension, wherein the twisting direction of the spiral extension opposite to the rotational direction of the camshaft ( 4 ) in order to improve the entry of the lubricant into the lubrication channels ( 6 ) to accomplish.