WO2018069134A1

WO2018069134A1 - Roller tappet for a piston pump, piston pump

Info

Publication number: WO2018069134A1
Application number: PCT/EP2017/075320
Authority: WO
Inventors: Daniel Keilbach; Benjamin Christian Martin; Markus Kunz; Benjamin Deschner
Original assignee: Robert Bosch Gmbh
Priority date: 2016-10-11
Filing date: 2017-10-05
Publication date: 2018-04-19
Also published as: DE102016219712A1

Abstract

Roller tappet (1) for a piston pump, in particular for a high-pressure fuel pump, for supporting a reciprocating pump piston (2) on a cam (3) or eccentric of an input shaft (4), comprising a tappet member (5) that has a front recess (6) inside which some portions of a roller (9) that is rotatably mounted on a pin (8) are accommodated in such a way that an axial bearing gap (7) is formed; furthermore, a radial bearing gap (10) is formed between the roller (9) and the pin (8), and the pin (8) is connected to the tappet member (5) for conjoint rotation therewith. A piston pump comprising a roller tappet (1) of said type is also disclosed.

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, having 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 AI. The known roller tappet comprises a plunger part, in which a roller is rotatably mounted about a rotation axis, so that it can roll on a cam of a drive shaft of a piston pump. The roller is arranged in an inner region of the plunger part facing the drive shaft. For rotatably supporting the roller, a bolt is inserted in the plunger part, the longitudinal axis of which runs perpendicular to the longitudinal axis of the roller plunger. The plunger member has two diametrically opposed openings through which the bolt passes. By means of an applied snap ring, the bolt is secured against axial movement. The roller can be mounted rotatably on the bolt directly or via a bearing bush. In order to minimize the wear in the rotary bearing of the roller, the plunger part has a passage for a lubricant, which opens into a groove which is provided in a peripheral region of the plunger part adjacent to an end face of the roller pointing in the direction of its axis of rotation in the inner casing and in the direction the longitudinal axis of the roller tappet extends. The lubricant reaching the inner region of the tappet part via the passage and the groove is therefore supplied via an axial bearing gap between the roller and the inner shell of the plunger part of the rotary bearing of the roller.

Based on the above-mentioned prior art, the present invention seeks to provide a roller tappet for a piston pump, in particular for a high-pressure fuel pump, which allows a modified, the bolt incorporating lubrication concept. In this way, in particular, the lubrication in the region of a radial bearing gap between the roller and the bolt is to be improved in order to provide a roller tappet which is particularly robust.

To solve the problem, the roller tappet is specified with the features of claim 1. Advantageous developments of the invention can be found in the dependent claims. Furthermore, a piston pump is proposed with such a roller tappet.

Disclosure of the invention

The roller tappet proposed for a piston pump, in particular for a high-pressure fuel pump, serves to support a liftable pump piston on a cam or eccentric of a drive shaft. It comprises a plunger body with a front-side recess, in which, forming an axial bearing gap, a roller rotatably mounted on a pin is partially received. In this case, a radial bearing gap is formed between the roller and the bolt. According to the invention, the bolt is rotatably connected to the plunger body.

The non-rotatable connection of the bolt with the plunger body prevents the bolt from rotating during operation of the piston pump with the roller. This means that the angular position of the bolt relative to the plunger body is fixed. The lubrication medium provided for lubricating the radial bearing gap can accordingly be guided via a lubricating path which extends at least in sections through the bolt. For example, the lubrication path can be guided via an inlet bore passing through the bolt in the axial direction and connected directly to the radial bearing gap via at least one branching additional inlet bore is. Such a lubrication concept is the subject of a further application of the applicant.

The realization of such a lubrication concept presupposes that the angular position of the bolt is predetermined in order to enable the connection of the inlet bores formed in the bolt to a region guiding the lubricant. This may be, for example, an axial bearing gap which is formed between the plunger body and the roller. Alternatively or additionally, the plunger body can have at least one radial bore, via which the inlet bores formed in the bolt can be supplied with the lubricating medium.

According to a preferred embodiment of the invention, the bolt has at its two end faces in each case an approach, via which it is non-positively and / or positively connected to the plunger body. Preferably, at least one positive connection is achieved in order to secure the bolt against rotation about its own longitudinal axis and / or against rotation about the longitudinal axis of the plunger body. The latter can be achieved, for example, in that the frontal projections of the bolt engage in recesses of the plunger body. In this case, the bolt is additionally supported by the projections on the plunger body, in a direction parallel to the longitudinal axis of the plunger body. If a positive connection between the bolt and the tappet body is also achieved via the lugs, the bolt is held captive in the tappet body. This is particularly advantageous when the bolt is inserted from the open end side of the plunger body forth in this.

Furthermore, preferably, the end-side projections of the bolt each have at least two parallel side edges. These allow insertion of the bolt from the open end side of the plunger body ago. The parallel side edges are therefore preferably aligned parallel to the longitudinal axis of the plunger body. About the parallel side edges of the bolt can also support in the direction of rotation of the plunger body, so that it is secured against rotation about its own longitudinal axis.

Ideally, the frontal projections of the bolt are inserted in recesses of the plunger body, which engage in the frontal recess of the plunger body. opposite to each other. In engagement with these recesses, the lugs cause a form fit, which secures the bolt at least against rotation about the longitudinal axis of the plunger body. In order to facilitate the insertion of the bolt in the end-side recess of the plunger body, the further recesses of the plunger body which are opposite the end-side recess are preferably open toward the end face of the plunger body. In this case, the bolt can be inserted from below into the plunger body. In order to keep the bolt - at least during assembly - captive in the ram body, it is proposed that it is pressed into the plunger body. The press fit can be effected via the end-side lugs of the bolt, which have a press excess with respect to a recess of the plunger body. For example, the limited by the two parallel side edges of a region of an end-face projection of the bolt have a pressing oversize relative to the approach receiving recess in the plunger body. Alternatively or additionally, the axial extent of the bolt, including the end-side lugs can be equipped with a press oversize.

In addition, it can be provided - as an alternative or in addition - that the position of the bolt in the plunger body is secured by at least one pin. The pin is preferably guided perpendicular to the longitudinal axis of the plunger body and parallel to the longitudinal axis of the bolt, so that the position of the bolt is secured in the direction of the longitudinal axis of the plunger body.

For example, the at least one pin can be used to secure the position of the bolt in a radial bore of the plunger body, preferably pressed, and engage in an axial bore of the bolt. The pin is then inserted after mounting the bolt. Unless the pin engages through the bolt in a further radial bore of the plunger body, which is the first radial bore diametrically opposite, two individual pins are provided, both of which are inserted from the outside diametrically opposed radial bores of the plunger body, so that they engage with get the axial bore of the bolt.

Alternatively it can be provided that a single pin is received in an axial bore of the bolt and the bolt has projecting end portions which engage in radial bores of the plunger body. To facilitate the assembly is called further education measure proposed that the pin is made in several parts and has two pin parts and an intermediate spring for radial bias of the pin parts relative to the plunger body. The multi-part executed pin can be used before the mounting of the bolt in the axial bore of the bolt. When inserting the bolt in the frontal recess of the plunger body, the two pin parts can be compressed against the spring force of the spring, so that are completely absorbed in the bolt. If the bolt has reached its end position, the end portions of the two pin parts are pressed by the spring force of the spring into the respective radial bore of the tappet body.

If a position securing the bolt is provided by means of at least one pin, preferably the pin receiving the axial bore in the bolt on a small game to prevent over-determination in conjunction with a support of the bolt on the two end-side lugs on the plunger body. Because during operation of a piston pump, in which the roller tappet is used, the bolt is pressed over the cam lift in the region of the two lugs against the plunger body. In order for the force to be dissipated via the plunger body and not via the pin, the axial bore receiving the pin is to be provided with clearance.

Since the proposed roller tappet allows the realization of novel lubrication concepts that include the bolt, it is proposed in a further development of the invention that the radial bearing gap between the roller and the bolt via at least one inlet bore formed in the bolt with a lubricant can be supplied. The non-rotatable connection of the bolt with the plunger body is a prerequisite of the lubricating concept, so that here the advantages of the invention are particularly well come into play. Preferably, an inlet bore passes through the bolt in the axial direction and is in communication with at least one radial bore of the tappet body serving as an inlet, so that the at least one inlet bore formed in the bolt can be acted upon by a lubricant via the radial bore of the tappet body.

In addition, 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 has an inventive Roller tappet is supported on a cam or eccentric of a drive shaft. The plunger body of the roller tappet is received in a cylinder bore of a housing part of the piston pump liftable. By using a

The roller tappet according to the invention, in conjunction with the novel lubricating concept, can reduce the wear in the region of the engine of the pump, so that the service life of the pump increases.

Advantageously, the cylinder bore of the housing part, in which the roller tappet is received liftable, connected to an engine-internal pressure oil supply line. In this case, the pressure oil can be used as a lubricating medium. The pressure prevailing in the pressure oil supply line supports the required lubrication.

A preferred embodiment of the invention will be explained in more detail with reference to the accompanying drawings. These show:

Fig. 1 is a schematic longitudinal section through an inventive

2 in a schematic side view of the roller tappet of FIG. 1,

3 is a schematic side view of the bolt of the roller tappet of FIG. 1 and FIG. 4 is a schematic longitudinal section through the pin of the roller tappet of FIG.

1.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a piston pump according to the invention with a roller tappet 1 for

Supporting a liftable pump piston 2 can be seen on a cam 3 of a rotating drive shaft 4. The rotation of the drive shaft 4 is converted via the roller tappet 1 into a stroke movement of the pump piston 2. For this purpose, the roller tappet 1 comprises one in a cylinder bore 26 of a housing part 27 the plunger pump liftably received plunger body 5 and an outer circumferentially on the cam 3 running off roller 9, which is rotatably mounted on a pin 8 for this purpose.

To supply a formed between the roller 9 and the bolt 8 radial bearing gap 10 with a lubricating medium, the bolt 8 Zulaufbohrun- gene 23, 24, which connect the radial bearing gap 10 with a region leading the lubricating medium. Because the inlet bores 23, 24 are connected via radial bores 25 which are formed in the plunger body 5, with an opening into the cylinder bore 26 pressure oil supply line 28. For uniform distribution of the lubricating medium within the cylinder bore 26, the plunger body 5 on the outer circumference side an annular groove 21 and two longitudinal grooves 18, which the

Ring groove 21 connect with the radial bores 25. Since the supply of the lubricating medium also leads via an axial bearing gap 7, at the same time the frontal contact area of the roller 9 is lubricated with the plunger body 5.

The illustrated lubrication concept presupposes a bolt 8 which is connected in a rotationally fixed manner to the tappet body 5. For this purpose, the bolt 8 at its end faces 11 lugs 12 which engage in recesses 14 of the plunger body 5, which are diametrically opposed to a front-side recess 6 for receiving the roller 9. As can be seen in particular from FIG. 3, the lugs 12 each have two parallel side edges 13, so that the bolt 8 including the roller 9 can be inserted from below into the frontal recess 6 of the tappet body 5. The parallel side edges 13 thereby come to rest on the side walls of the front-side recess 6 of the plunger body 5 diametrically opposed recesses 14, so that hereby the bolt 8 is secured against rotation about its own longitudinal axis AB and about the longitudinal axis As of the plunger body 5 , About an arcuate extending further side edge 13 ', the bolt 8 is supported at the same time on the plunger body 5.

The frontal lugs 12 of the bolt 8 may have a pressing excess over the recesses 14 of the plunger body 5, so that the bolt 8 is held captive in the plunger body 5. The press excess has the bolt 8 preferably between the two parallel side edges 13. Alternatively or additionally, at least one pin 15 can be used to secure the position of the bolt 8. As shown by way of example in FIGS. 1 and 2, a multi-part design

Pin 15 may be used, which comprises a first pin part 15.1 and a second pin part 15.2 and a spring 22 (see also Fig. 4). The multi-part executed pin 15 is inserted into an axial bore 17 of the bolt 8 prior to insertion or pressing of the bolt 8 in the plunger body 5. If now the bolt 8 is pushed from below into the front-side recess 6 of the tappet body 5, the two pin parts 15.1,

15.2 compressed against the spring force of the spring 22 until the bolt 8 has reached its final position and the spring 22, the two pin member 15.1, 15.2 apart so that their end portions 19, 20 engage in radial bores 16 of the plunger body 5.

Claims

claims

1. roller tappet (1) for a piston pump, in particular for 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) with a frontal recess (6), in the formation of an axial bearing gap (7) on a bolt (8) rotatably mounted roller (9) is partially received, wherein between the roller (9) and the bolt (8) a radial bearing gap (10) is formed,

characterized in that the bolt (8) rotatably connected to the plunger body (5).

2. roller tappet (1) according to claim 1,

characterized in that the bolt (8) at its two end faces (11) each have a projection (12) via which the bolt (8) with the plunger body (5) non-positively and / or positively connected.

3. roller tappet (1) according to claim 2,

characterized in that the lugs (12) each have at least two parallel side edges (13).

4. roller tappet (1) according to claim 2 or 3,

characterized in that the projections (12) in recesses (14) of the plunger body (5) used, preferably pressed, which are diametrically opposed to the frontal recess (6) of the plunger body (5) and preferably to the end face of the plunger body (5 ) are opened.

5. roller tappet (1) according to one of the preceding claims,

characterized in that the position of the bolt (8) in the plunger body (5) by at least one pin (15) is secured.

6. roller tappet (1) according to claim 5,

characterized in that the pin (15) inserted into a radial bore (16) of the plunger body (5), preferably pressed, and in an axial bore (17) of the bolt (8) engages.

7. roller tappet (1) according to claim 5,

characterized in that the pin (15) in an axial bore (17) of the bolt (8) is received and the bolt (8) projecting end portions (19, 20) which engage in radial bores (16) of the plunger body (5).

8. roller tappet (1) according to claim 5 or 7,

characterized in that the pin (15) is designed in several parts and two pin parts (15.1, 15.2) and an intermediate spring (22) for radially biasing the pin parts (15.1, 15.2) relative to the plunger body (5).

9. roller tappet (1) according to one of the preceding claims,

characterized in that the radial bearing gap (10) between the roller (9) and the bolt (8) via at least one in the bolt (8) formed inlet bore (23, 24) can be supplied with a lubricant, preferably an inlet bore (23) the bolt (8) penetrates in the axial direction and is in communication with at least one radial bore (25) of the tappet body (5) serving as an inlet.

10. 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 (26) of a

Housing part (27) of the piston pump is received liftable.