CN107709711B

CN107709711B - Roller tappet for piston pump, and piston pump

Info

Publication number: CN107709711B
Application number: CN201680034004.9A
Authority: CN
Inventors: Z·阿克卡亚; G·迈尔; F·内克尔; M·马耶尔; A·杜特
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-06-12
Filing date: 2016-04-21
Publication date: 2020-06-23
Anticipated expiration: 2036-04-21
Also published as: WO2016198193A1; DE102015210815A1; CN107709711A

Abstract

The invention relates to a roller tappet (1) for a piston pump for supporting a pump piston (2) that can be moved to a distance on a cam (3) or eccentric of a drive shaft (4), comprising a tappet body (5) and a hollow-cylindrical roller (6) which is received in a recess (7) at the end of the tappet body (5) in some regions and is mounted on a pin (9) in a rotatable manner directly or indirectly via a bearing bush (8), such that a radial bearing gap (10) is formed between the roller (6) and the pin (9) or between the roller (6) and the bearing bush (8), which can be supplied with a lubricating medium via a bore (11) formed in the tappet body (5) and opening into the recess (7). According to the invention, the roller (6) has a geometry (15) that influences the flow of the lubricating medium in the region of its outer circumferential surface (12) and/or in the region of its inner circumferential surface (13) and/or in the region of at least one end surface (14).

Description

Roller tappet for piston pump, and piston pump

Technical Field

The invention relates to a tappet for a piston pump, in particular a high-pressure fuel pump, having a roller tappet according to the invention. The roller tappet serves to support a pump piston of the piston pump on a cam or eccentric of the drive shaft. The invention further relates to a piston pump, in particular a high-pressure fuel pump for supplying an internal combustion engine with fuel, having such a roller tappet.

Background

Roller tappets of the above-mentioned type are known, for example, from the publication DE 102012223413 a 1. The known roller tappet has a tappet portion which can be supported on the drive by means of a roller which is rotatably mounted in the tappet portion. In order to minimize wear in the bearing region and in this way increase the service life of the pump, it is proposed that the bearing region is lubricated better by at least one channel and groove provided in the tappet section. The channel connects an inner region of the tappet section, in which the bearing structure of the roller is arranged, with the housing of the tappet section. The arrangement of the channels is carried out in such a way that: the channel opens into the groove. The groove is arranged in its inner housing in the peripheral edge region of the tappet section adjoining the end side of the roller in the direction of its axis of rotation and extends in the direction of the longitudinal axis of the roller tappet. The lubricant which reaches the interior region of the tappet section through the channel therefore first supplies the axial bearing gap between the roller and the inner shell of the tappet section.

Disclosure of Invention

Starting from the prior art cited above, the invention is based on the task of: the lubrication in the region of the radial bearing play of the roller tappet for a piston pump, which is formed between the roller and the pin for rotatably mounting the roller or between the roller and the bearing bush, is improved. In this way, a roller tappet that is less susceptible to wear is proposed.

In order to solve this object, a roller tappet is proposed for a roller tappet of a piston pump, in particular a high-pressure fuel pump, for supporting a pump piston that can be moved to a distance on a cam or eccentric of a drive shaft, comprising a tappet body and a hollow-cylindrical roller which is received in a recess on the end face of the tappet body and is mounted on a pin in a rotatable manner directly or indirectly via a bearing bush, such that a radial bearing gap is formed between the roller and the pin or between the roller and the bearing bush, which can be supplied with a lubricating medium via at least one bore hole formed in the tappet body and opening into the recess, wherein the roller has at least one bore hole in the region of its outer circumferential surface and/or in the region of its inner circumferential surface and/or in the region of at least one end face, which affects the lubrication Geometry of the flow of the medium, wherein the geometry is a circumferential projection which is formed in the region of the inner circumferential surface and is located in front of the radial bearing gap, the projection having a side facing the radial bearing gap which is inclined at an angle to the inner circumferential surface, wherein the angle is less than 90 °.

Furthermore, a piston pump is proposed, which comprises a stroke-movable pump piston, which is supported on a cam or eccentric of a drive shaft by means of the roller tappet, wherein a tappet body of the roller tappet is received in a cylinder bore of a housing part of the piston pump in a stroke-movable manner.

In the following, advantageous embodiments of the invention are described.

In order to support the stroke-movable pump piston on the cam or eccentric of the drive shaft, the roller tappet proposed comprises a tappet body and a hollow-cylindrical roller which is partially received in an end-side recess of the tappet body and is mounted on the pin in a rotatable manner directly or indirectly via a bearing bush. The radial bearing gap formed between the roller and the pin or between the roller and the bearing bush can be supplied with a lubricating medium by at least one bore formed in the tappet body and opening into a recess at the end face of the tappet body. According to the invention, the roller has at least one geometry influencing the flow of the lubricating medium in the region of its outer circumferential surface and/or in the region of its inner circumferential surface and/or in the region of at least one end face.

Due to the influencing of the flow of the lubricating medium by the geometry, at least a partial quantity of the lubricating medium can be supplied in a targeted manner to the radial bearing gap. Preferably, therefore, the influence consists in a diversion of the flow of the lubricating medium. As a result, the amount of lubrication supplied to the radial bearing gap is increased, which is accompanied by better lubrication and less wear in the region of the component bounding the radial bearing gap.

The influence of the lubricating medium flow can also be: at least a partial amount of the lubricating medium is captured and maintained, so that in each operating state a sufficient amount of lubricating medium for lubricating and cooling the roller tappet is available in the region of the radial bearing gap.

In order to ensure that a sufficient amount of lubricating medium is present for use in the respective operating state of the roller tappet, it has hitherto been necessary to maintain a clearly increased amount of lubrication. With the roller tappet according to the invention, the amount of lubrication can be reduced, since a defined lubrication state in the radial bearing gap can be achieved by the proposed geometry. The reduction in the amount of lubrication in turn results in an increase in the efficiency of the system.

According to a preferred first embodiment of the invention, the geometry is an annular groove which is formed in the region of the inner circumferential surface of the roller and is located in front of the radial bearing gap. At least a partial quantity of the lubricating medium supplied through the bore provided in the tappet body can be captured by the annular groove, so that a reservoir for the lubricating medium is formed. The radial bearing gap can be continuously supplied with lubricating medium from the reservoir to ensure the necessary lubrication.

For this purpose, an annular groove serving as a reservoir is provided in the region of the inner circumferential surface of the roller, to be precise upstream of the radial bearing gap. This ensures that, on the one hand, at least a partial flow of the lubricating medium is supplied to the reservoir and, on the other hand, that the lubricating medium obtained from the reservoir reaches the radial bearing gap.

Furthermore, this embodiment of the invention makes use of centrifugal forces which are caused by the rotational movement of the rollers and which lead to an increased hydraulic pressure in the annular groove. The increased hydraulic pressure facilitates the supply of the radial bearing gap with lubricating medium stored in the annular groove.

The annular groove provided in the region of the 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 a circumferential projection which is formed in the region of the inner circumferential surface of the roller and which is located upstream of the radial bearing gap, the projection having a flank facing the radial bearing gap, which flank is inclined at an angle to the inner circumferential surface which is less than 90 °. Preferably, the angle is less than 70 °, further preferably less than 50 °. The inclined side faces of the projecting circumferential projection form a feed hopper, via which the lubricating medium is supplied in a targeted manner to the radial bearing gap. The centrifugal force caused by the rotational movement of the rollers also advantageously acts here, since it reinforces the positive guidance by the inclined side faces.

According to a preferred third embodiment of the invention, the geometry is a groove which is formed in the region of the inner circumferential surface of the roller and is located upstream of the radial bearing gap, which groove extends from the end face of the roller up to the radial bearing gap and is arranged at an angle counter to the direction of rotation of the roller. This means that the groove extends away from the end face in the direction opposite to the direction of rotation of the roller. The grooves, in combination with the rotational movement of the rollers, contribute to the build-up of hydraulic pressure on the edges of the radial bearing gap, which contributes to the build-up of a constant lubrication film. Preferably, a plurality of similar grooves are arranged at the same angular distance from one another in the region of the inner circumferential surface of the roller, since this advantageous effect is reinforced by the plurality of grooves.

Alternatively or additionally, it is proposed that the geometry be a groove formed in the region of the outer circumferential surface, which extends from the center of the roller toward the end face and is arranged at an angle counter to the direction of rotation of the roller. This embodiment utilizes a drag flow on the outer circumferential surface of the roller, so that the lubricating medium surrounding the roller on the outer circumferential side is guided in a targeted manner into the bearing region to be lubricated. The radial bearing gap is formed between the tappet body and the end face of the roller and/or the bearing bush, on the one hand, and the axial bearing gap, on the other hand. Preferably, a plurality of similar grooves are formed with the same angular distance to one another in the region of the outer circumferential surface. The grooves are preferably inclined in such a way that they are directed 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 bore provided for supplying the radial bearing gap with the lubricating medium preferably extends radially inwardly from the outer circumference of the tappet body as far as the groove, in which the roller is partially received. In this way, the lubricating medium surrounding the tappet body can be used for lubricating the roller bearing. For this purpose, the bore ensures the necessary connection of the groove of the tappet body, in which the roller is received, with the cylinder bore, in which the tappet body is received.

Preferably, the bore opens into the groove in the region of the axial bearing gap, which is formed between the tappet body and the end face of the roller and/or the bearing bush. In this way, it is ensured that the lubricating medium is sufficiently supplied not only to the radial bearing gap but also to the axial bearing gap. The bore can in particular be guided radially or obliquely through the wall of the tappet body.

Furthermore, a piston pump, in particular a high-pressure fuel pump for the fuel supply of an internal combustion engine, is proposed, which comprises a pump piston that can be moved by a stroke and is supported on a cam or eccentric of a drive shaft by means of the roller tappet according to the invention. In this case, the tappet body of the roller tappet is received in a stroke-movable manner in a cylinder bore of a housing part of the piston pump. The advantages of the roller tappet according to the invention are also achieved in the case of a pump comprising such a roller tappet, since the reduced wear in the bearing region of the roller tappet has the effect of extending the service life of the pump.

Preferably, the tappet body is secured in the cylinder bore in a torsionally fixed manner. The anti-rotation device is particularly advantageous when the proposed geometry for influencing the flow of the lubricating medium is dependent on the direction of rotation of the roller. The anti-rotation device ensures that the direction of rotation of the roller is always the same.

Advantageously, a bore provided in the tappet body for supplying the radial bearing gap with a lubricating medium engages into a pressurized oil supply line inside the engine. Therefore, it is not necessary to maintain a separate lubricating medium. Furthermore, the pressure in the pressure oil supply line facilitates the supply of the lubricating medium into the region of the roller bearing arrangement.

Drawings

Preferred embodiments of the present invention are explained in detail below with reference to the accompanying drawings. The figures show:

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

fig. 2 shows a schematic longitudinal section through a roller tappet according to the invention according to a first preferred embodiment in the region of a geometry provided on the roller,

fig. 3 shows a schematic longitudinal section through a roller tappet according to the invention according to a second preferred embodiment in the region of a geometry provided on the roller,

fig. 4 shows a schematic longitudinal section through a roller tappet according to the invention according to a third preferred embodiment in the region of a geometry provided on the roller,

figure 5 shows in enlarged view a schematic top view of the inner peripheral surface of the roller of figure 4,

figure 6 is a schematic top view of a roller tappet according to the present invention according to a fourth preferred embodiment,

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

Detailed Description

Fig. 1 shows a piston pump according to the invention, which has a roller tappet 1 for supporting a pump piston 2 that can be moved to a stroke on a cam 3 of a rotating drive shaft 4. Since the pump piston 2 is supported on the cam 3 by the roller tappet 1, the rotation of the drive shaft 4 is converted into a stroke movement of the pump piston 2. For this purpose, the roller tappet 1 comprises a tappet body 5, which is received in a cylinder bore 19 of a housing part 20 of the piston pump in a stroke-movable manner, and a roller 6, which is received in a recess 7 at the end face of the tappet body 5 and is mounted so as to be rotatable. The rotatable mounting of the roller 6 is achieved by a pin 9 which traverses the tappet body 5 in the region of the groove 7 and is fixed at its end in the tappet body 5. In the roller tappet 1 shown in fig. 1, a bearing bush 8 is arranged between the bolt 9 and the roller 6, which is not, however, absolutely necessary. The roller 6 is rotatable about a rotational axis 22, which is arranged perpendicular to a longitudinal axis 23 of the roller tappet 1 and parallel to a longitudinal axis 24 of the drive shaft 4.

As can be further gathered from fig. 1, a pressure oil supply line 21, through which oil is supplied as a lubricating medium to the cylinder bore 19, opens into the cylinder bore 19 of the housing part 20. The lubricating medium reaches the bearing region of the roller 6 via an annular gap 25 formed between the tappet body 5 and the housing part 20. In order to ensure a radial bearing gap 10 formed between the roller 6 and the bearing bush 8 with the lubricating medium, at least one bore 11 is provided in the tappet body 5, said bore extending from the outer circumference of the tappet body 5 obliquely radially inward and opening into the groove 7. The bore 11 is arranged such that it opens into the recess 7 in the region of the axial bearing gap 18, to be precise such that the opening region lies opposite the radial bearing gap 10 on the axial bearing gap 18. In this way, the centrifugal force caused by the rotational movement of the rollers can be used to distribute the lubricating medium.

Furthermore, in order to optimize the lubrication of the radial bearing gap 10, the roller 6 of the roller tappet 1 from fig. 1 has a geometry 15 in the form of an annular groove arranged in the region of its inner circumferential surface 13, upstream of the radial bearing gap 10. The lubricating medium which has passed through the bore hole 11 into the axial bearing gap 18 accumulates in the annular groove, so that a lubricating medium reservoir is formed at the inlet of the radial bearing gap 10, by means of which lubricating medium can be continuously supplied to the radial bearing gap 10.

Fig. 2 shows an enlarged view of the geometry 15 embodied as an annular groove. The arrows show the direction of flow of the lubricating medium. The lubricating medium is first pressed by centrifugal force to the radial outside. Since the geometry 15 embodied as an annular groove is located upstream of the radial bearing gap 10, a partial amount of the lubricating medium is captured. The pressure in the annular groove is increased by the lubricant medium accumulating in the annular groove, so that the supply of the radial bearing gap 10 with lubricant medium is thereby also promoted.

Another geometry 15 is known from fig. 3. It is configured as a circumferential projection with an inclined side 16 in front of the radial bearing gap 10, thus forming a hopper. The lubricant is supplied to the radial bearing gap 10 in a targeted manner via the side faces 16.

Another possible configuration of the geometry 15 can be seen from fig. 4. Instead of the circumferential grooves, a plurality of grooves are provided which are arranged opposite to the direction of rotation 17 of the rollers 6 and are distributed uniformly over the inner circumferential surface 13 (see fig. 5). The slot achieves: a partial quantity of the lubricating medium is supplied in a targeted manner to the radial bearing gap 10.

Fig. 6 shows a further possibility for constructing the geometry 15. The outer circumferential surface 12 of the roller 6 has grooves which are directed obliquely outward from the center of the roller 6, i.e., against the direction of rotation 17 of the roller 6. The grooves extend as far as the lateral end faces 14 of the rollers 6, so that, in particular, the lubricating medium is thereby guided from the grooves 7 of the tappet body 5 into the axial bearing gap 18. This applies in particular when the supply of the lubricating medium into the groove 7 takes place via a bore 11' which passes through the tappet body 5 (see also fig. 7) in the axial direction. Since this effect depends on the direction of rotation 17 of the roller 6, the tappet body 5 has a rotation prevention device 26 in the form of a groove on the outer circumference for receiving a pin or the like.

Fig. 7 shows an extension for optimizing the lubrication. The cross-sectional shape of the groove 7 is selected such that the gap remaining between the outer circumferential surface 12 of the roller 6 and the tappet body 5 has a gap width which decreases in the direction of rotation 17 of the roller 6. This results in a pressure rise in this gap which, in particular, reinforces the action of the peripheral side groove similar to the embodiment of fig. 6.

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

Claims

1. Roller tappet (1) for a piston pump for supporting a stroke-movable pump piston (2) on a cam (3) or eccentric of a drive shaft (4), comprising a tappet body (5) and a hollow-cylindrical roller (6) which is received in a partial region in an end-side recess (7) of the tappet body (5) and is mounted on a pin (9) in a rotatable manner directly or indirectly via a bearing bush (8), such that a radial bearing gap (10) is formed between the roller (6) and the pin (9) or between the roller (6) and the bearing bush (8), which can be supplied with a lubricating medium via at least one bore hole (11) formed in the tappet body (5) and opening into the recess (7),

wherein the roller (6) has at least one geometry (15) that influences the flow of the lubricating medium in the region of its outer circumferential surface (12) and/or in the region of its inner circumferential surface (13) and/or in the region of at least one end surface (14),

characterized in that the geometry (15) is a circumferential projection which is formed in the region of the inner circumferential surface (13) and which is located in front of the radial bearing gap (10), said projection having a side surface (16) facing the radial bearing gap (10) which is at an angle (α) to the inner circumferential surface (13)₁) Is inclined, wherein the angle (α)₁) Less than 90.

2. The roller tappet according to claim 1, characterised in that the geometry (15) is a groove which is formed in the region of the outer circumferential surface (12), extends from the middle of the roller (6) towards the end face (14) and is at an angle (α)₃) Is arranged against the direction of rotation (17) of the roller (6).

3. Roller tappet according to claim 1 or 2, characterised in that the bore (11) for supplying the radial bearing gap (10) with a lubricating medium extends radially inwards from the outer circumference of the tappet body (5) as far as the groove (7).

4. The roller tappet according to claim 1 or 2, characterised in that the bore (11) opens into the groove (7) in the region of an axial bearing gap (18) which is formed between the tappet body (5) and the end face (14) of the roller (6) and/or the bearing bush (8).

5. The roller tappet according to claim 1, characterised in that the roller tappet (1) is provided for a high-pressure fuel pump.

6. The roller lifter of claim 1, characterized in that the angle (α)₁) Less than 70 deg..

7. The roller lifter of claim 1, characterized in that the angle (α)₁) Less than 50.

8. The roller tappet according to claim 2, characterised in that there are a plurality of the grooves which are configured at the same angular distance from one another in the region of the outer circumferential surface (12).

9. A roller tappet according to claim 3, characterised in that the bore (11) extends radially or obliquely.

10. Piston pump, comprising a stroke-movable pump piston (2) which is supported on a cam (3) or eccentric of a drive shaft (4) by means of a roller tappet (1) according to one of the preceding claims, wherein a tappet body (5) of the roller tappet (1) is received in a cylinder bore (19) of a housing part (20) of the piston pump in a stroke-movable manner.

11. Piston pump according to claim 10, characterised in that the tappet body (5) is secured in a torsionally fixed manner in the cylinder bore (19).

12. Piston pump according to claim 10 or 11, characterised in that a bore (11) provided in the tappet body (5) for supplying the radial bearing gap (10) with a lubricating medium engages on a pressure oil supply line (21) inside the engine.

13. Piston pump according to claim 10, characterised in that the piston pump is a high-pressure fuel pump for the fuel supply of an internal combustion engine.