DE102015210815A1 - Roller tappet for a piston pump, piston pump - Google Patents

Abstract

The invention relates to a roller tappet (1) for a piston pump, in particular a high-pressure fuel pump, for supporting a liftable pump piston (2) on a cam (3) or eccentric drive shaft (4) comprising a plunger body (5) and a hollow cylindrical roller (6 ), which is partially received in a frontal recess (7) of the plunger body (5) and is rotatably mounted directly or indirectly via a bearing bush (8) on a bolt (9), so that between the roller (6) and the bolt (9 ) or between the roller (6) and the bearing bush (8) a radial bearing gap (10) is formed, which is at least one in the plunger body (5) formed and in the recess (7) opening bore (11) supplied with a lubricant , According to the invention, the roller (6) in the region of its outer peripheral surface (12), in the region of its inner peripheral surface (13) and / or in the region of at least one end face (14) has at least one geometry (15) influencing the flow of the lubricating medium. Furthermore, the invention relates to a piston pump with such a roller tappet (1).

Description

The invention relates to a roller tappet for a piston pump, in particular a high-pressure fuel pump, with the features of the preamble of claim 1. The roller tappet serves to support a pump piston of the piston pump to a cam or eccentric drive shaft. Furthermore, the invention relates to a piston pump, in particular a high-pressure fuel pump for supplying an internal combustion engine with fuel, with such a roller tappet.

State of the art

A roller tappet of the type mentioned above is an example of the published patent application DE 10 2012 223 413 A1 out. The known roller tappet has a tappet part which can be supported on a drive device via a roller rotatably mounted in the tappet part. In order to minimize wear in the bearing area and thus increase the life of the pump, improved lubrication of the bearing area over at least one provided in the ram part passage and a groove is proposed. The passage connects an inner region of the plunger part, in which the bearing of the roller is arranged, with the outer casing of the plunger part. The arrangement of the passage takes place in such a way that it opens into the groove. In this case, the groove is provided in a circumferential region of the tappet part adjacent to an end face of the roller facing in the direction of its axis of rotation in its inner casing and extends in the direction of the longitudinal axis of the roller tappet. Accordingly, the lubricant passing via the passage into the inner region of the tappet part is primarily supplied to an axial bearing gap between the roller and the inner jacket of the tappet part.

Based on the above-cited prior art, the present invention has the object to improve the lubrication in the region of a radial bearing gap of a roller tappet for a piston pump between a roller and a pin for rotatably supporting the roller or between the roller and a bearing bush is trained. In this way, a roller tappet is to be created, which is less susceptible to wear.

To solve the problem, the roller tappet is specified with the features of claim 1. Furthermore, the piston pump is proposed with the features of claim 8. Advantageous developments of the invention can be found in the respective subclaims.

Disclosure of the invention

The proposed for supporting a hubbeweglichen pump piston on a cam or eccentric drive shaft roller tappet comprises a plunger body and a hollow cylindrical roller which is partially received in an end recess of the plunger body and rotatably supported directly or indirectly via a bearing bush on a bolt. A trained between the roller and the bolt or between the roller and the bearing bush radial bearing gap is supplied via at least one opening formed in the plunger body and opening into the frontal recess of the plunger bore with a lubricating medium. According to the invention, the roller in the region of its outer circumferential surface and / or in the region of its inner peripheral surface and / or in the region of at least one end face has at least one geometry influencing the flow of the lubricating medium.

By influencing the flow of the lubricating medium over the geometry, at least a subset of the lubricating medium can be selectively supplied to the radial bearing gap. The influence is therefore preferably in a deflection of the flow of the lubricant. As a result, the amount of lubricant supplied to the radial bearing gap increases, which is accompanied by improved lubrication and less wear in the area of the radial bearing gap defining components.

The influencing of the flow of the lubricating medium may also be to collect and maintain at least a subset of the lubricating medium, so that in each operating state, a sufficient amount of the lubricating medium for lubrication and cooling of the roller tappet is available in the region of the radial bearing gap.

To ensure that the roller tappet in any operating condition, a sufficient amount of lubricant is available, so far had a significantly increased amount of lubricant be kept. When using a roller tappet according to the invention, the amount of lubricant can be reduced because of the proposed geometry, a defined state of lubrication in the radial bearing gap can be achieved. The reduction in the amount of lubricant in turn leads to an increase in the efficiency of the system.

According to a first preferred embodiment of the invention, the geometry is formed in the region of the inner peripheral surface of the roller and the radial bearing gap upstream annular groove. About the annular groove can at least a subset of the lubricating medium supplied via the bore provided in the tappet body can be collected, so that a kind of depot for the lubricating medium is formed. From the depot, the radial bearing gap continuously lubricating medium can be supplied to ensure the required lubrication.

Serving as a depot annular groove is this arranged in the region of an inner peripheral surface of the roller and that before the radial bearing gap. This ensures, on the one hand, that at least one partial stream of the lubricating medium is supplied to the depot and, on the other hand, that lubricant taken from the depot enters the radial bearing gap.

Further, this embodiment of the invention utilizes the centrifugal force due to the rotational movement of the roller causing increased hydraulic pressure in the annular groove. The increased hydraulic pressure promotes the supply of the radial bearing gap with the lubricant stored in the annular groove.

The annular groove provided in the region of an inner circumferential surface of the roller can be produced both by a material-removing method and by a material-applying method.

According to a second preferred embodiment of the invention, the geometry is formed in the region of the inner peripheral surface of the roller and the radial bearing gap upstream circumferential nose having a radial bearing gap facing edge, which is inclined relative to the inner peripheral surface at an angle which is less than 90 ° , Preferably, the angle is less than 70 °, more preferably less than 50 °. The inclined flank of the protruding circumferential nose forms an inlet funnel, over which the radial bearing gap targeted lubricating medium is supplied. Again, the attributable to the rotational movement of the roller centrifugal force has a positive effect, since it enhances the forced operation on the inclined flank.

According to a third preferred embodiment of the invention, the geometry is a formed in the region of the inner peripheral surface of the roller and the radial bearing gap upstream groove extending from the end face of the roller to the radial bearing gap and is set at an angle to the direction of rotation of the roller. That is, the groove extends away from the end face in a direction opposite to the direction of rotation of the roll. The groove, in combination with the rotational movement of the roller, contributes to establishing a hydraulic pressure at the edge of the radial bearing gap, which contributes to the formation of a constant lubricating film. Preferably, a plurality of similar grooves are formed at the same angular distance from one another in the region of the inner peripheral surface of the roller, since the number of grooves, the advantageous effect can be increased.

Alternatively or additionally, it is proposed that the geometry is a groove formed in the region of the outer peripheral surface, which extends from the center of the roller to an end face and is set at an angle to the direction of rotation of the roller. This embodiment makes use of a drag flow on the outer circumferential surface of the roller, so that lubricating medium, which surrounds the outside circumference of the roller, is guided specifically into the bearing areas to be lubricated. These are on the one hand to the radial bearing gap, on the other hand to an axial bearing gap, which is formed between the plunger body and the end face roller and / or the bearing bush. Preferably, a plurality of identical grooves are formed at the same angular distance from each other in the region of the outer peripheral surface. The grooves are preferably inclined so that they lead from the center of the roller in the direction of rotation of the roller obliquely outward in the direction of the respective end face.

The provided for supplying the radial bearing gap with a lubricating medium bore preferably extends from the outer periphery of the plunger body radially inward to the recess in which the roller is partially received. In this way, the lubricating medium surrounding the plunger body can be used to lubricate the roller bearing. For this purpose, the bore ensures the necessary connection of the recess of the tappet body, in which the roller is received, with the cylinder bore, in which the tappet body is accommodated.

Preferably, the bore opens in the region of an axial bearing gap, which is formed between the plunger body and an end face of the roller and / or the bearing bush, in the recess. In this way, an adequate supply of both the radial bearing gap, and the axial bearing gap is ensured with lubricating medium. The bore can be guided in particular radially or obliquely through the wall of the plunger body.

Furthermore, a piston pump, in particular a high-pressure fuel pump for supplying fuel to an internal combustion engine, is proposed which comprises a liftable pump piston which is supported on a cam or eccentric of a drive shaft via a roller tappet according to the invention. The plunger body of the roller tappet is in a cylinder bore of a Housing part of the piston pump received liftable. The advantages of the roller tappet according to the invention also come into play in a pump comprising the roller tappet, since the reduced wear in the bearing areas of the roller tappet results in an extension of the service life of the pump.

Preferably, the plunger body is secured against rotation in the cylinder bore. The rotation is especially important if the proposed geometry for influencing the flow of the lubricant depends on the direction of rotation of the role. The anti-twist device ensures that the direction of rotation of the roller is always the same.

Advantageously, the hole provided in the tappet body, which serves to supply the radial bearing gap with a lubricating medium, is connected to an engine-internal pressure oil supply line. Accordingly, no separate lubricant medium must be provided. The pressure prevailing in the pressure oil supply line also promotes the supply of the lubricating medium in the region of the roller bearing.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. These show:

1 a schematic longitudinal section through a piston pump according to the invention in the region of the roller tappet,

2 a schematic longitudinal section through a roller tappet according to the invention according to a first preferred embodiment in the area provided on the roll geometry,

3 a schematic longitudinal section through a roller tappet according to the invention according to a second preferred embodiment in the area provided on the roll geometry,

4 a schematic longitudinal section through a roller tappet according to the invention according to a third preferred embodiment in the area provided on the roll geometry,

5 a schematic plan view of the inner peripheral surface of the role of 4 in an enlarged view,

6 a schematic plan view of a roller tappet according to the invention according to a fourth preferred embodiment and

7 a schematic longitudinal section through a roller tappet according to the invention according to a fifth preferred embodiment.

Detailed description of the drawings

Of the 1 is a piston pump according to the invention with a roller tappet 1 for supporting a liftable pump piston 2 on a cam 3 a rotating drive shaft 4 refer to. By the support of the pump piston 2 on the cam 3 over the roller tappet 1 becomes the rotation of the drive shaft 4 in a stroke movement of the pump piston 2 transformed. The roller plunger 1 for this purpose comprises a plunger body 5 standing in a cylinder bore 19 a housing part 20 the piston pump is received in a liftable manner, and a roller 6 , which are in a frontal recess 7 of the plunger body 5 partially recorded and rotatably supported. The rotatable storage of the roll 6 is about a bolt 9 causes the ram body 5 in the region of the recess 7 interspersed and at its ends in the ram body 5 is held. In the in the 1 illustrated roller tappet 1 is between the bolt 9 and the role 6 a bearing bush 8th arranged, which is not mandatory. The role 6 is about a rotation axis 22 rotatable, perpendicular to a longitudinal axis 23 of the roller tappet 1 and parallel to a longitudinal axis 24 the drive shaft 4 is arranged.

Again 1 can also be seen, opens into the cylinder bore 19 of the housing part 20 a pressurized oil supply line 21 , over which the cylinder bore 19 Oil is supplied as a lubricant. About an annular gap 25 that is between the tappet body 5 and the housing part 20 is formed, the lubricating medium enters the storage area of the roll 6 , To supply a radial bearing gap 10 that's between the role 6 and the bearing bush 8th is formed to ensure with the lubricant is in the tappet body 5 at least one hole 11 provided, extending from the outer periphery of the plunger body 5 extends obliquely radially inward and into the recess 7 empties. The hole 11 is arranged such that it is in the region of an axial bearing gap 18 into the recess 7 opens, in such a way that the mouth region the radial bearing gap 10 at the axial bearing gap 18 is opposite. In this way, the attributable to the rotational movement of the roller centrifugal force can be used to distribute the lubricant.

To optimize the lubrication of the radial bearing gap 10 has the role 6 of the roller tappet 1 of the 1 also one in the area of its inner peripheral surface 13 arranged geometry 15 in the form of a radial bearing gap 10 upstream ring groove on. In the annular groove that accumulates over the hole 11 in the axial bearing gap 18 reaching lubricating medium, so that at the entrance of the radial bearing gap 10 a lubricant reservoir is formed, via which the radial bearing gap 10 continuously lubricating medium can be fed.

An enlarged view of a designed as an annular groove geometry 15 is the 2 refer to. The arrows represent the direction of flow of the lubricating medium. The centrifugal force initially forces the lubricating medium radially outward. Since the geometry designed as an annular groove 15 the radial bearing gap 10 is upstream, a subset of the lubricant is collected. As a result of the lubricating medium collecting in the annular groove, the pressure in the annular groove increases, so that in this case the supply of the radial bearing gap 10 is still promoted with the lubricant.

Another geometry 15 is the 3 refer to. It is designed as a circumferential nose, the one the radial bearing gap 10 upstream inclined flank 16 has, so that an inlet funnel is formed. Over the flank 16 becomes the radial bearing gap 10 specifically supplied lubricant.

Of the 4 may be another possible embodiment of the geometry 15 be removed. Instead of a circumferential groove here are several, contrary to the direction of rotation 17 the role 6 employees and over the inner peripheral surface 13 evenly spaced grooves provided (see 5 ). The grooves cause a subset of the lubricant targeted the radial bearing gap 10 is supplied.

Another way to form the geometry 15 is in the 6 shown. Here, the outer peripheral surface 12 the role 6 several grooves on the middle of the roll 6 are guided obliquely outwards, against the direction of rotation 17 the role 6 , The grooves extend to the lateral end faces 14 the role 6 , so that here in particular lubricating medium from the recess 7 of the plunger body 5 in the axial bearing gap 18 to be led. This is especially true when the supply of the lubricating medium in the recess 7 about holes 11 ' takes place, which the ram body 5 in the axial direction prevail (see also 7 ). Because the effect of the direction of rotation 17 the role 6 depends, the ram body 5 an anti-twist device 26 in the form of an outer peripheral side recess for receiving a pin or the like.

A further education measure for the optimization of the lubrication is the 7 refer to. Here is the cross-sectional shape of the recess 7 such that a between the outer peripheral surface 12 the role 6 and the plunger body 5 remaining gap a in the direction of rotation 17 the role 6 has decreasing gap width. This leads to a pressure increase in the gap, in particular the effect of outer peripheral side grooves analogous to the embodiment of the 6 strengthened.

All measures described with reference to the figures for optimizing the lubrication can be applied individually or in different combinations.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012223413 A1 [0002]

Claims (10)

Roller tappets ( 1 ) for a piston pump, in particular a high-pressure fuel pump, for supporting a liftable pump piston ( 2 ) on a cam ( 3 ) or eccentric of a drive shaft ( 4 ) comprising a plunger body ( 5 ) and a hollow cylindrical roll ( 6 ), which in a front-side recess ( 7 ) of the tappet body ( 5 ) in some areas and directly or indirectly via a bushing ( 8th ) on a bolt ( 9 ) is rotatably mounted, so that between the roller ( 6 ) and the bolt ( 9 ) or between the role ( 6 ) and the bearing bush ( 8th ) a radial bearing gap ( 10 ) is formed, the at least one in the tappet body ( 5 ) and in the recess ( 7 ) opening bore ( 11 ) can be supplied with a lubricating medium, characterized in that the roller ( 6 ) in the region of its outer peripheral surface ( 12 ) and / or in the region of its inner peripheral surface ( 13 ) and / or in the region of at least one end face ( 14 ) at least one geometry influencing the flow of the lubricating medium ( 15 ) owns. Roller tappet according to claim 1, characterized in that the geometry ( 15 ) one in the region of the inner peripheral surface ( 13 ) and the radial bearing gap ( 10 ) is upstream annular groove. Roller tappet according to claim 1, characterized in that the geometry ( 15 ) one in the region of the inner peripheral surface ( 13 ) and the radial bearing gap ( 10 ) upstream circumferential nose, the one the radial bearing gap ( 10 ) facing flank ( 16 ), which is opposite the inner peripheral surface ( 13 ) is inclined at an angle (α ₁ ), wherein the angle (α ₁ ) is less than 90 °, preferably less than 70 °, more preferably less than 50 °. Roller tappet according to claim 1, characterized in that the geometry ( 15 ) one in the region of the inner peripheral surface ( 13 ) and the radial bearing gap ( 10 ) is an upstream groove extending from the end face ( 14 ) of the role ( 6 ) into the radial bearing gap ( 10 ) and at an angle (α ₂ ) against the direction of rotation ( 17 ) of the role ( 6 ) is employed, wherein preferably a plurality of such grooves at the same angular distance from each other in the region of the inner peripheral surface ( 13 ) are formed. Roller tappet according to one of the preceding claims, characterized in that the geometry ( 15 ) one in the region of the outer peripheral surface ( 12 ) formed groove extending from the middle of the roll ( 6 ) to an end face ( 14 ) and at an angle (α ₃ ) against the direction of rotation ( 17 ) of the role ( 6 ) is employed, wherein preferably a plurality of such grooves at the same angular distance from each other in the region of the outer peripheral surface ( 12 ) are formed. Roller tappet according to one of the preceding claims, characterized in that the bore ( 11 ) for the supply of the radial bearing gap ( 10 ) with a lubricant from the outer periphery of the plunger body ( 3 ) radially inward to the recess ( 7 ), wherein preferably the bore ( 11 ) extends radially or obliquely. Roller tappet according to one of the preceding claims, characterized in that the bore ( 11 ) in the region of an axial bearing gap ( 18 ) in the recess ( 7 ), which between the tappet body ( 5 ) and the face ( 14 ) of the role ( 6 ) and / or the bearing bush ( 7 ) is formed. Piston pump, in particular high-pressure fuel pump for supplying fuel to an internal combustion engine, comprising a liftable pump piston ( 2 ), which via a roller tappet ( 1 ) according to one of the preceding claims on a cam ( 3 ) or eccentric of a drive shaft ( 4 ) is supported, wherein the plunger body ( 5 ) of the roller tappet ( 1 ) in a cylinder bore ( 19 ) of a housing part ( 20 ) of the piston pump is received liftable. Piston pump according to claim 8, characterized in that the plunger body ( 5 ) in the cylinder bore ( 18 ) is secured against twisting. Piston pump according to claim 8 or 9, characterized in that in the plunger body ( 5 ) provided bore ( 11 ), the supply of the radial bearing gap ( 10 ) with a lubricating medium, to an engine-internal pressure oil supply line ( 21 ) connected.

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