WO2016198193A1

WO2016198193A1 - Roller tappet for a piston pump, piston pump

Info

Publication number: WO2016198193A1
Application number: PCT/EP2016/058840
Authority: WO
Inventors: Zafer AKKAYA; Gerhard Meier; Frieder Necker; Markus Majer; Andreas Dutt
Original assignee: Robert Bosch Gmbh
Priority date: 2015-06-12
Filing date: 2016-04-21
Publication date: 2016-12-15
Also published as: CN107709711B; CN107709711A; DE102015210815A1

Abstract

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

Description

Description title

Roller tappet for a piston pump, piston pump 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 a combustion engine with fuel, with such a roller tappet.

State of the art

A roller tappet of the aforementioned type is shown by way of example from the disclosure DE 10 2012 223 413 Al. The well-known roller tappet has a

Plunger part, which is supported via a rotatably mounted in the plunger part roller on a drive device. 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 area of the

Plunger part, in which the bearing of the roller is arranged, with the outer jacket 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 peripheral region of the plunger part adjoining an end face of the roller pointing in the direction of its axis of rotation in its inner jacket and extends in the direction of the longitudinal axis of the roller plunger.

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 roller tappet proposed for supporting a liftable pump piston on a cam or eccentric of a drive shaft comprises a tappet body and a hollow cylindrical roller which, in an end recess of the

Plunger body received in some areas and is rotatably mounted directly or indirectly on 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 is available for lubricating and cooling the roller plunger 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. At least a subset of the lubricant medium supplied via the bore provided in the tappet body can be collected via the annular groove, 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 peripheral surface of the roller, so that lubricating medium, which surrounds the outside circumference of the roller, is guided in a targeted manner 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 La- Gerspalt 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 received in a cylinder bore of a housing part of the piston pump 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 particularly important if the proposed geometry for influencing the flow of the lubricant from the direction of rotation of the Role is dependent. 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 shows a schematic longitudinal section through a piston pump according to the invention in the region of the roller tappet,

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

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

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

5 is a schematic plan view of the inner peripheral surface of the roller of Fig. 4 in an enlarged view,

Fig. 6 is a schematic plan view of a roller tappet according to the invention according to a fourth preferred embodiment and Fig. 7 is a schematic longitudinal section through a roller tappet according to the invention according to a fifth preferred embodiment.

Detailed description of the drawings

FIG. 1 shows a piston pump according to the invention with a roller tappet 1 for supporting a lifting pump piston 2 on a cam 3 of a rotating drive shaft 4. By supporting the pump piston 2 on the cam 3 via 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 liftable manner in a cylinder bore 19 of a housing part 20 of the piston pump, and a roller 6, which is partially received and rotatably mounted in a frontal recess 7 of the tappet body 5. The rotatable mounting of the roller 6 is effected via a pin 9, which passes through the plunger body 5 in the region of the recess 7 and is held at its ends in the plunger body 5. In the roller tappet 1 shown in FIG. 1, a bearing bush 8 is arranged between the pin 9 and the roller 6, which, however, is not absolutely necessary. The roller 6 is rotatable about a rotation 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.

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

To optimize the lubrication of the radial bearing gap 10, the roller 6 of the roller tappet 1 of Fig. 1 also has a arranged in the region of its inner peripheral surface 13 geometry 15 in the form of the radial bearing gap 10 upstream annular groove. In the annular groove, the reaching over the bore 11 in the axial bearing gap 18 lubricating medium collects, so that at the entrance of the radial bearing gap 10, a lubricating medium 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 shown in FIG. 2. The arrows represent the direction of flow of the lubricating medium. The centrifugal force initially forces the lubricating medium radially outward. Since the geometry formed as an annular groove 15 is disposed upstream of the radial bearing gap 10, a subset of the lubricating medium is collected. The pressure in the annular groove increases as a result of the lubricating medium collecting in the annular groove, so that the supply of the radial bearing gap 10 with the lubricating medium is still promoted.

Another geometry 15 is shown in FIG. 3. It is designed as a circumferential nose, which has a radial bearing gap 10 upstream inclined edge 16, so that an inlet funnel is formed. About the edge 16 is the radial bearing gap 10 selectively supplied lubricating medium.

4, a further possible embodiment of the geometry 15 can be removed. Instead of a circumferential groove here several opposite to the direction of rotation 17 of the roller 6 employed and over the inner peripheral surface 13 evenly distributed grooves provided (see Fig. 5). The grooves cause that a subset of the lubricating medium is selectively supplied to the radial bearing gap 10.

Another possibility for forming the geometry 15 is shown in FIG. 6. Here, the outer peripheral surface 12 of the roller 6 has a plurality of grooves which are guided obliquely outwardly from the center of the roller 6, against the direction of rotation 17 of the Roller 6. The grooves extend up to the lateral end faces 14 of the roller 6, so that in particular lubricating medium from the recess 7 of the

Tappet body 5 is guided in the axial bearing gap 18. This applies in particular when the supply of the lubricating medium into the recess 7 via holes 11 ', which pass through the plunger body 5 in the axial direction (see also Fig. 7). Since the effect of the direction of rotation 17 of the roller 6 is dependent, the plunger body 5 has a rotation 26 in the form of an outer peripheral side recess for receiving a pin or the like.

A further development measure for the optimization of the lubrication is shown in FIG. 7. Here, the cross-sectional shape of the recess 7 is selected such that a remaining between the outer peripheral surface 12 of the roller 6 and the plunger body 5 gap has a decreasing in the direction of rotation 17 of the roller 6 gap width. This leads to an increase in pressure in the gap, which in particular reinforces the effect of outer peripheral side grooves analogously to the embodiment of FIG.

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

Claims

claims

1. 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 front-side recess (7) of the plunger body (5) and is rotatably mounted directly or indirectly on 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 can be supplied with a lubricating medium via at least one bore (11) formed in the plunger body (5) and opening into the recess (7),

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 surface (14) has at least one geometry (15) which influences the flow of the lubricating medium. has.

2. Roller tappet according to claim 1,

characterized in that the geometry (15) is in the region of the inner peripheral surface (13) formed and the radial bearing gap (10) upstream annular groove.

3. roller tappet according to claim 1,

characterized in that the geometry (15) is in the region of the inner peripheral surface (13) formed and the radial bearing gap (10) upstream circumferential nose, which has a radial bearing gap (10) facing edge (16), with respect to the inner peripheral surface ( 13) at an angle (α-ι) is inclined, wherein the angle (α-ι) is less than 90 °, preferably less than 70 °, more preferably less than 50 °.

4. roller tappet according to claim 1,

characterized in that the geometry (15) is in the region of the inner circumferential surface (13) formed and the radial bearing gap (10) upstream groove extending from the end face (14) of the roller (6) into the radial bearing gap ( 10) and at an angle (a ₂ ) against the direction of rotation (17) of the roller (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.

5. Roller tappet according to one of the preceding claims,

characterized in that the geometry (15) is a groove formed in the area of the outer circumferential surface (12) extending from the center of the roller (6) towards an end face (14) and at an angle (a ₃ ) the direction of rotation (17) of the roller (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.

6. Roller tappet according to one of the preceding claims,

characterized in that the bore (11) for supplying the radial bearing gap (10) with a lubricant from the outer periphery of the plunger body (3) extends radially inward to the recess (7), wherein preferably the bore (11) extends radially or obliquely ,

7. Roller tappet according to one of the preceding claims,

characterized in that the bore (11) in the region of an axial bearing gap (18) opens into the recess (7) between the plunger body (5) and the end face (14) of the roller (6) and / or the bearing bush (7 ) is formed.

8. piston pump, in particular high-pressure fuel pump for fuel supply of an internal combustion engine, comprising a liftable pump piston (2) which is supported via a roller tappet (1) according to one of the preceding claims on a cam (3) or eccentric drive shaft (4), wherein

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.

9. Piston pump according to claim 8,

characterized in that the plunger body (5) in the cylinder bore (18) is secured against rotation.

10. Piston pump according to claim 8 or 9,

characterized in that in the plunger body (5) provided bore (11), which serves to supply the radial bearing gap (10) with a lubricating medium, to an engine-internal pressure oil supply line (21) is connected.