EP2985447B1 - High-pressure fuel pump with roller tappet - Google Patents

Description

The present invention relates to a high-pressure fuel pump with a roller tappet. The roller tappet carries at a free end a roller which cooperates with a cam of a shaft.

A roller tappet finds z. B. in a high-pressure fuel pump insert that drives a piston on the roller tappet, which moves the piston of the high-pressure fuel pump. In the high-pressure fuel pump, a rotary motion of a cam of a shaft is converted into a linear motion for pressure generation.

High-pressure fuel pumps are used, for example, in the common-rail injection. In such exemplary injection systems for internal combustion engines, the high-pressure fuel pumps bring the fuel to a high pressure level. The pressurized fuel fills a piping system that is constantly under pressure during engine operation. The pressure generated by the high-pressure fuel pump is when using diesel as fuel between 1600 bar and 3000 bar and when using gasoline as a fuel between 200 bar and 300 bar. Higher or lower values can usually be attributed to the boundary conditions, as e.g. the engine is too cold or too hot, the engine is under load or idle, the injector is heavily polluted, or the injection volume is incompatible with the injection controller values.

The force-transmitting element is usually a roller that runs on a shaft with a defined cam contour. The roller is mounted radially in a roller tappet, which transmits the force to the piston of the high-pressure fuel pump. Due to unavoidable geometrical deviations, the operation becomes additional transferred axial forces to the role that must be collected constructively.

The German patent application DE 10 2012 221 604 A1 discloses a roller tappet for a high-pressure fuel pump. The roller tappet has a sleeve-shaped first ram part, over which the roller tappet is guided in a receptacle. The roller tappet also has an inserted into the first plunger part second plunger part in which a roller is rotatably mounted, via which the roller plunger is supported on a drive device.

The German patent application DE 10 2010 026 326 A1 discloses a roller tappet for a high-pressure fuel pump of an internal combustion engine. A bridge piece on the drive side of the roller tappet has a cup-like receptacle with a cam roller mounted therein. Between the inner shell of the roller tappet and the end face of the cam roller a separate contact body is provided. This contact body is used for an immediate lateral start of the end of the cam follower roller. In the event that the contact body is formed as a ball, this consists of hardened steel or ceramic.

Another high-pressure fuel pump with a roller tappet is off WO 2010/026463 A known.

The invention has for its object to provide a high-pressure fuel pump with a roller tappet, wherein the roller tappet has a simple structure, is inexpensive to manufacture and also has a mechanical stability that withstands the loads of the roller tappet in a high-pressure fuel pump.

The above object is achieved by a high-pressure fuel pump with a roller tappet comprising the features of claim 1.

The roller tappet of the high-pressure fuel pump carries at a free end a component which holds a roll. The component is at one Outer wall of the roller tappet held by a first leg, a second leg and a roller tappet at least partially circumferential tab. The first leg, the second leg and the circumferential tab are designed such that they do not project beyond an outer circumference of the outer wall of the roller tappet. A bracket interconnecting the first leg and the second leg has formed a recess through which the roller is in operative contact with the cam of the shaft.

The advantage of the high-pressure fuel pump according to the invention with the roller tappet is that a single component is attached externally to the roller tappet, which at the same time rotatably supports the roller at the free end of the roller tappet. The attachment of the component to the outer wall of the roller tappet simplifies the installation of the high-pressure fuel pump considerably.

The roller tappet has advantageously formed in the outer wall two extending in the direction of its axis grooves, which serve to receive the first leg and the second leg of the single component. The grooves extending in the direction of its axis preferably have a depth which is equal to or greater than a thickness of the first leg and the second leg, respectively. For attachment of the component, the roller tappet preferably further has an at least partially extending over its circumference circumferential groove which connects the two extending in the direction of the axis of the roller tappet grooves. The tab is advantageously received in the attached to the roller tappet component in the circumferential groove. The tab preferably connects the first leg with the second leg. The circumferential groove preferably has a depth equal to or greater than a thickness of the tab.

Another advantage of the component supporting the roller is that the two legs and the tab have a thickness that is equal to or less than the depth of the axial grooves or the circumferential groove.

In the case of the component mounted on the roller tappet, there are thus advantageously no elements which disturb the lifting movement of the roller tappet.

The first leg and the second leg advantageously have each embossed a contact surface for the role in such a way that the contact surfaces on both sides of the recess in this partially protrude. In addition, the recess in the bracket is preferably limited by two webs connecting the first leg with the second leg.

The advantage of the arrangement of the contact surfaces is that the roller rotatably supported by the contact surfaces can engage through the recess. The two webs, which connect the first leg to the second leg, preferably ensure stability of the component in the axial direction of the roller during operation of the high-pressure fuel pump.

The component is preferably flat and consists of the first leg and the second leg, which are both connected to one another via a bracket. The bracket has advantageously formed the recess. The first leg preferably carries the tab and the second leg has advantageously punched out a recess into which the tab can be received. For this purpose, the tab has preferably formed at a free end a shape which is complementary to a shape of the recess.

The component is advantageously designed as a flat punched part and has a bending line between the first leg and the bracket and a bending line formed between the bracket and the second leg. Furthermore, the flat punched part has preferably formed a bending point at the transition from the first leg to the tab.

The advantage of the flat stamped part is that all elements for the storage of the roller and the mounting of the component are formed on the roller tappet in one operation (punching operation).

The roller can thus be stored directly in the mounted on the roller tappet component without an additional part must be pressed. This has a positive effect on the entire tolerance chain. Furthermore, the solution offers an advantage that in the assembled component, the recess-limiting webs provide a radial securing of the roll. In addition, the attachment of the roller on the roller tappet with the stamped part, which is bent to the component, also given a very economical method is given.

The first leg and the second leg have advantageously each formed an impression for the contact surface of the roller in the immediate vicinity of the recess. As already mentioned above, the recess in the bracket is preferably delimited by two webs which connect the contact surface for the first roller in the first leg with the contact surface for the roller in the second leg. Thus, the roller is fixed in the direction of the axis of the roller, which gives the entire fuel high-pressure pump in operation a favorable mechanical stability.

According to one embodiment, the first leg of the component for attachment to the roller tappet has formed the tab with a shaped hook. The hook then engages in the attachment of the component on the roller tappet preferably in a correspondingly complementary hook-shaped recess on the second leg. The fixation of the hook in the hook-shaped recess may be accomplished by laser welding or another alternative method, such as e.g. Gluing or soldering, done.

The inventive method for mounting a roller tappet is characterized in that initially a flat stamped part is punched out of a metal sheet. The stamped part has a first leg and a second leg, which are both connected via a bracket. In the bracket, a recess for receiving a roller is formed. On the first leg a tab with eg a molded hook is provided. On the second leg a complementary hook-shaped recess is formed accordingly. In the stamped part by means of an impression two contact surfaces are embossed for the role. The contact surfaces are formed in the immediate vicinity of the recess for the role or engage in part in the recess.

The advantage is that the stamped part is made in such a way that it can be used for mounting on the roller tappet without any additional additional and to be attached elements. For this purpose, the first and the second leg are bent along the intended bending lines at an angle of 70 ° to 100 ° (depending on the configuration of the roller tappet) to the bracket. When bent along the bend lines by exactly 90 °, the first and second legs are parallel. The roller is held in such a way by the contact surfaces that it engages through the recess in the bracket. The first leg and the second leg are each inserted into a groove extending in the direction of the axis of the roller tappet. The grooves are formed in an outer wall of the roller tappet. Finally, the tab of the first leg is so bent into a circumferential groove on the outer wall of the roller tappet, so that the hook of the tab of the first leg engages in a hook-shaped recess of the second leg.

With an additional fixation of the hook of the tab of the first leg are connected to the hook-shaped recess of the second leg. Likewise, the entire component can be fixed to the roller tappet in order to ensure a spatially constant position of the component on the roller tappet during operation of the high-pressure fuel pump.

Figur 1

eine Kraftstoffhochdruckpumpe des Standes der Technik;

Figur 2

eine Seitenansicht eines freien Endes eines Rollenstößels, der zur Aufnahme eines Bauteils mit der Rolle entsprechend ausgebildet ist;

Figur 3

eine Querschnittsansicht durch das freie Ende des Rollenstößels;

Figur 4

eine Draufsicht auf ein flächiges Stanzteil, aus dem das Bauteil zur Aufnahme der Rolle und Befestigung derselben am Rollenstößel geformt wird;

Figur 5

eine Seitenansicht des flächige Stanzteils; und

Figur 6

eine Seitenansicht des Rollenstößels mit einem daran befestigten einzigen Bauteil, das die Rolle trägt, welche mit einer Nocke zusammenwirkt.

In the following, embodiments of the invention and their advantages with reference to the accompanying figures will be explained in more detail. The proportions in the figures do not always correspond to the actual size ratios, as some shapes are simplified and other shapes are shown enlarged in relation to other elements for ease of illustration. Showing:

FIG. 1

a high-pressure fuel pump of the prior art;

FIG. 2

a side view of a free end of a roller tappet, which is designed to receive a component corresponding to the role;

FIG. 3

a cross-sectional view through the free end of the roller tappet;

FIG. 4

a plan view of a flat stamped part from which the component for receiving the roller and fixing it is formed on the roller tappet;

FIG. 5

a side view of the flat stamped part; and

FIG. 6

a side view of the roller tappet with a single component attached thereto, which carries the roller, which cooperates with a cam.

For identical or equivalent elements of the invention, identical reference numerals are used. The illustrated embodiments are only examples of how a roller tappet and a method for mounting a roller tappet can be configured and thus do not represent a final limitation of the invention.

FIG. 1 shows a high-pressure fuel pump 100 according to the prior art. A roller tappet 1 carries at a free end 4 a roller 2 which cooperates with a cam 6 of a camshaft 7. The cam 6 is designed such that a rotational movement of the camshaft 7 is converted into a stroke movement H of the roller tappet 1. The roller tappet 1 is guided in a cylinder 3. by virtue of the lifting movement H of the roller tappet 1, a fuel in the cylinder 3 is compressed.

FIG. 2 shows the roller tappet 1, for receiving a component 10 (s. Fig. 4 ) is designed according to a free end 4. For receiving the component 10, the roller tappet 1 has in its outer wall 24 in each case two opposing grooves 20 formed. These grooves 20 extend in the direction of the axis A of the roller tappet 1. To secure the component 10 on the roller tappet 1, a circumferential groove 22 is formed in the outer wall 24 of the roller tappet 1 in addition to the axially extending grooves 20. This circumferential groove 22 connects the two axial grooves 20. The circumferential groove 22 has a depth T2 which is equal to or greater than a thickness D2 of a circumferential tab 15 (see Fig. 5 ). In other words, a first leg 11, a second leg 12 and the circumferential tab 15 of the component 10 are arranged in the assembled state on the outer wall 24 of the roller tappet 1 that they do not project beyond an outer periphery 25 of the roller tappet 1.

FIG. 3 shows a cross-sectional view through the free end 4 of the roller tappet 1. According to the embodiment shown here, the roller tappet 1 has two in the direction of its projecting into the plane of the axis A extending and opposing grooves 20 formed. The grooves 20 serve to receive the first leg 11 and the second leg 12 (see FIGS. 4 and 6 ) of the component 10. The grooves 20 have a depth T1 which is equal to or greater than a thickness D1 of the first leg 11 and the second leg 12 (see Fig. 5 ).

FIG. 4 shows a plan view of a stamped part 30, from which ultimately the single component 10 is produced by a bending operation, so as to mount the roller 2 (not shown here) on the roller tappet 1 or fix. The stamped part 30 is punched out of a metal sheet. The stamped part 30 is substantially rectangular and has a pair of parallel long sides 32 and bounded by a pair of short sides 34 arranged at right angles to the parallel long sides 32. On a long side 32 of the first leg 11 carries the tab 15 and the second leg 12 has a recess 19 punched out. The stamped part 30 thus consists of the first leg 11 and the second leg 12. These two legs 11, 12 are connected to one another via a bracket 13. In the bracket 13, a molding 14 is formed. The molding 14 has two webs 17 which connect the first leg 11 with the second leg 12.

The stamped part 30 also has two indentations 16E which provide a contact surface 16 in the first leg 11 and in the second leg 12 for the roller 2 of the roller tappet 1. In the region of each indentation 16E, the flat stamped part 30 is provided in each case on the parallel long sides 32 with a bulge 36, which contribute to the mechanical stabilization as material reinforcement. In the finished and bent component 10, a roller 2 (not shown here) passes through the recess 14 and is held in the two contact surfaces 16. By the contact surfaces 16 thus the roller 2 is fixed in the direction of an axis R of the roller 2. For mechanical stability during operation in the high-pressure fuel pump 100 of the component 10 also contribute to the two webs 17 of the bracket 13, whereby the roller 2 is spatially fixed in its axis R in the finished component 10.

For bending the finished component 10, bending lines 26 are provided in the immediate vicinity of the contact surface 16, along which the first leg 11 and the second leg 12 are bent at an angle (between 70 ° and 100 °) to the bracket 13. According to the embodiment shown here, the flat punched part 30 has on the first leg 11, the tab 15 with a hook 18 at the free end 15E of the tab 15 and the second leg 12 has a hook-shaped recess 19. This hook 18 is formed such that it at the am Roller tappet 1 mounted component 10 engages in the hook-shaped recess 19 of the second leg 12. To the intervention the hook 18 in the hook-shaped recess 19 is also provided at the transition from the first leg 11 to the tab 15 in the region of the neck on the first leg 11, a further bending point 27.

FIG. 5 shows a side view of the stamped part 30. The first leg 11 and the second leg 12 have a thickness D1. Similarly, the tab 15 has a thickness D2. In the event that the stamped part 30 is punched out of a uniformly flat sheet metal part, the stamped part 30 has a uniform thickness.

FIG. 6 shows the roller 2, which is fastened by means of the component 10 on the roller tappet 1. The first leg 11 and the second leg 12 of the component 10 are inserted and pressed in the direction of the axis A of the roller tappet 1 extending groove 20. At this time, the roller 2 is already supported by the contact surfaces 16. At the in Fig. 6 As shown, only the second leg 12 can be seen. The roller 2 engages through the recess 14 of the component 10 and thus cooperates with a cam 6 of a shaft 7. As already in the description too Fig. 1 The contact surfaces 16 of the single component 10 secure the roller 2 in the direction of the axis R of the roller 2. Likewise, the two webs 17 connect the first leg 11 and the second leg 12 and thus contribute to a further axial stability of the roller 2 at. The attached to the first leg 11 tab 15 is bent around the roller tappet 1 and then located in the circumferential groove 22 of the roller tappet 1. The hook 18 of the tab 15 then engages in a recess 19 of the second leg 12 a. Thus, the only component 10 that carries the roller 2, supported on the outer wall 24 of the roller tappet 1 and secured. For further securing or fixing of the component 10 on the outer wall 24 of the roller tappet 1, a fixation can be additionally produced. This fixation can z. B. are produced by laser welding, gluing or soldering.

As from the representation of Fig. 6 can be seen, the axially extending grooves 20 and the circumferential groove 22 have such a depth T1 and T2 (see Figures 2 and 3 ) is formed so that it is equal to or slightly larger than the thickness D1 of the first leg 11 and second leg 12 of the stamped part 30 and also equal to or slightly larger than the thickness D2 of the tab 15. This has the advantage that attached to the roller tappet 1 component 10 does not protrude and thus does not hinder the lifting movement H of the roller tappet 1 or leads to a disturbance of the lifting movement H of the roller tappet 1.

LIST OF REFERENCE NUMBERS

1

roller plunger

2

role

3

cylinder

4

free end

6

cam

7

wave

10

single component

11

first leg

12

second leg

13

hanger

14

recess

15

flap

15E

Free end of the tab

16

approach surface

16E

impressing

17

web

18

hook

19

hook-shaped recess

20

groove

22

circumferential groove

24

outer wall

25

outer periphery

26

elastic line

27

bend

30

stamping

32

long page

34

short page

36

bulge

100

High-pressure fuel pump

A

axis

D1

Thickness of the first or second leg

D2

Thickness of the tab

R

Axis of the roll

T1

Depth of the axial grooves

T2

Depth of the circumferential groove

Claims (11)

1. High-pressure fuel pump (100) having a roller tappet (1) which, on a free end (4), bears a roller (2) which, during operation, interacts in a controllable manner with a cam (6) of a shaft (7),
   characterized in that
   a component (10) is, by way of a first limb (11), a second limb (12) and a lug (15) which runs at least partially around the roller tappet (1), held on an outer wall (24) of the roller tappet (1) in such a way that the first limb (11), the second limb (12) and the encircling lug (15) of the component (10) do not project beyond an outer circumference (25) of the outer wall (14) of the roller tappet (1), and a bracket (13) which connects the first limb (11) and the second limb (12) to one another has formed out of it a cutout (14) through which the roller (2) is in operative contact with the cam (6) of the shaft (7).
2. High-pressure fuel pump (100) according to Claim 1, wherein the roller tappet (1) has two grooves (20) formed so as to run in the direction of the axis (A) of said roller tappet, which grooves serve for receiving the first limb (11) and the second limb (12) respectively of the component (10), and wherein the grooves (20) are formed with a depth (T1) equal to or greater than a thickness (D1) of the first limb (11) or of the second limb (12).
3. High-pressure fuel pump (100) according to Claim 2, wherein the roller tappet (1) has a circumferential groove (22) formed so as to run over at least part of the circumference of said roller tappet, which circumferential groove connects the two grooves (20) running in the direction of the axis (A) of the roller tappet (1) and receives the lug (15) which connects the first limb (11) to the second limb (12), wherein the circumferential groove (22) is formed with a depth (T2) equal to or greater than a thickness (D2) of the lug (15).
4. High-pressure fuel pump (100) according to the preceding claims, wherein the first limb (11) and the second limb (12) each have a running surface (16) for the roller (2) stamped therein such that the running surfaces (16) project partially into the cutout (14) on both sides of said cutout.
5. High-pressure fuel pump (100) according to the preceding claims, wherein the cutout (14) in the bracket (13) is delimited by two webs (17) which connect the first limb (11) to the second limb (12).
6. High-pressure fuel pump (100) according to the preceding claims, wherein the component (10) is an areal punched part (30) delimited by a pair of parallel long sides (32) and by a pair of short sides (34) which are arranged at right angles to the parallel long sides, wherein the bracket (13) connects the first limb (11) and the second limb (12) to one another and, on a long side (32), the first limb (11) bears the lug (15) and the second limb (12) has a further cutout (19) punched out of it.
7. High-pressure fuel pump (100) according to Claim 6, wherein the lug (15) has, on a free end (15E), a shape complementary to a shape of the further cutout (19).
8. High-pressure fuel pump (100) according to Claim 7, wherein the shape on the free end (15E) of the lug (15) is a hook (18).
9. High-pressure fuel pump (100) according to one of Claims 6 to 8, wherein the areal punched part (30) has a bending line (26) formed between the first limb (11) and the bracket (13) and a bending line (26) formed between the bracket (13) and the second limb (12).
10. High-pressure fuel pump (100) according to one of Claims 6 to 8, wherein the areal punched part (30) has a bending point (27) at the transition from the first limb (11) to the lug (15).
11. High-pressure fuel pump (100) according to one of Claims 6 to 10 and according to Claim 4, wherein each stamped portion (16E) for a running surface (16) in the first limb (11) and in the second limb (12) of the areal punched part (30) bears, in each case on the parallel long sides (32), a protuberance (36) as a material reinforcement.

Images