EP2409014B1 - High pressure pump and tappet assembly - Google Patents

Description

The present invention relates to a high pressure pump for a fuel injection device of an internal combustion engine according to the preamble of claim 1 and a plunger assembly for a high pressure pump according to the preamble of claim 10.

State of the art

High-pressure pumps for fuel injectors of internal combustion engines are known in the prior art, which have a plunger assembly with pressed into a plunger body roller shoe. In this case, the plunger assembly is driven by a rotationally driven drive shaft of the high pressure pump, for example, against the force of a return spring in a lifting movement.

In DE 103 45 061 A1 or WO 2005 031150 a high-pressure pump is described with at least one plunger assembly, which in turn has a hollow cylindrical plunger body and a roller shoe inserted therein in the direction of the longitudinal axis of the plunger body, in which a roller is rotatably mounted. The high-pressure pump has at least one pump element, which in turn has a pump piston, by which a pump working space is limited. The plunger assembly is disposed between the pump piston and a rotationally driven drive shaft of the high pressure pump, wherein the drive shaft has at least one cam or eccentric on which the roller runs. The plunger body is guided displaceably in a bore of a housing part of the high-pressure pump. The ram assembly serves to the rotational movement of the drive shaft in a To convert stroke movement of the pump piston. In the ram assembly described above, the roller shoe is press-fitted into the ram body.

Since the ram group must take up especially acting perpendicular to the axis of rotation of the roller and the drive shaft lateral forces safely, all components must be performed with very low manufacturing tolerances.

Due to the required tolerances of the plunger assembly, however, it often comes with the press-fitting of the roller shoe in the plunger body to a Schrägeinpressung. This in turn leads to disadvantageous or incorrect press-in or holding forces of the press fit consisting of roller shoe and plunger body.

Therefore, it is necessary to provide a high-pressure pump with a plunger assembly having a robust ram assembly interference fit in which an accurate and improved press-fitting of the roller shoe is ensured in the plunger body.

Disclosure of the invention Advantages of the invention

According to the invention, a high-pressure pump is provided for a fuel injection device of an internal combustion engine, which has at least one pump element with a pump piston defining a pump chamber, wherein between the pump piston and a drive shaft of the high-pressure pump driven in rotation, a plunger assembly is provided with a plunger body and a pressed into a receptacle of the plunger body roller shoe wherein the plunger body has a centering guide for pressing the roller shoe. The provision according to the invention of the centering guide enables an improved press-fitting of the roller shoe into the tappet body. A Schräginpressung is avoided, the centering an automatic centering is achieved, and thereby a robust ram assembly interference fit is created. In addition, the press-in forces, if the plunger body is provided with a centering, not distorted.

Preferably, the centering guide is provided in the region of the receptacle.

According to a further preferred embodiment, the receptacle is cylindrical section-shaped, wherein the receptacle has an inner circumference, on which the centering guide is provided.

According to yet another preferred embodiment, the centering guide on a chamfer.

Preferably, the receptacle has a first end portion and a second end portion, wherein at the second end portion a radially projecting from the inner periphery inwardly abragender stop or projection is provided, and wherein the first end portion of an element of the drive shaft, in particular a cam or an eccentric , is opposite.

More preferably, the centering guide is provided at the first end portion.

According to a further preferred embodiment, the centering guide is provided over a height of the first end portion in a range of 2 to 10 mm, in particular 4 mm.

It is furthermore preferred if the chamfer has a depth a in the range of 0.1 to 0.01 mm, in particular of 0.05 mm, and in an angle range of 30 to 60 °, in particular with an angle of 45 ° is trained. A weakening of the plunger body by a centering guide with the above dimensions or in the above dimensional ranges has no adverse effects on the ram assembly interference fit. Neither the axial distance between the plunger body and the roller shoe is negatively affected in the plunger assembly during insertion or a pressure relief after pressing compared to a plunger assembly without centering, still affects a centering with the dimensions given above on the radial deformation of the plunger body during the pressing in and subsequent pressure relief negative. Rather, arises in terms of Plunger body with centering a more favorable deformation of the plunger body.

Preferably, the roller shoe is formed with a cylindrical excess pressure, which in particular has a value P _{ü, nenn} of 9 microns.

According to the invention, a plunger assembly for a high-pressure pump for a fuel injector of an internal combustion engine, with a plunger body and a pressed into a receptacle of the plunger body roller shoe is also provided, wherein the plunger body has a centering for pressing in the roller shoe. The plunger assembly is robust by providing the centering guide and has the advantages already described above.

Brief description of the drawings

Fig. 1

einen Längsschnitt durch eine Hochdruckpumpe gemäß dem Stand der Technik;

Fig. 2

einen Ausschnitt II oder Stößelbaugruppe der Hochdruckpumpe von Fig. 1;

Fig. 3A, 3B, 3C

jeweils einen Ausschnitt einer Stößelbaugruppe gemäß dem Stand der Technik vor, beim und nach dem Einpressvorgang;

Fig. 4A, 4B, 4C

jeweils einen Ausschnitt einer Stößelbaugruppe gemäß einer Ausführungsform vor, beim und nach dem Einpressvorgang;

Fig. 5A

eine Detailansicht des in Fig. 3A gezeigten Einbauzustands;

Fig. 5B

eine Detailansicht des in Fig. 4A gezeigten Einbauzustands; und

Fig. 6

eine weitere Detailansicht des in Fig. 5B gezeigten Einbauzustands.

Hereinafter, embodiments of the invention will be described in more detail with reference to the accompanying drawings. It shows:

Fig. 1

a longitudinal section through a high-pressure pump according to the prior art;

Fig. 2

a section II or plunger assembly of the high pressure pump of Fig. 1 ;

FIGS. 3A, 3B, 3C

in each case a section of a plunger assembly according to the prior art before, during and after the pressing-in process;

FIGS. 4A, 4B, 4C

in each case a section of a plunger assembly according to an embodiment before, during and after the pressing-in process;

Fig. 5A

a detailed view of the in Fig. 3A shown installation state;

Fig. 5B

a detailed view of the in Fig. 4A shown installation state; and

Fig. 6

another detail view of the in Fig. 5B shown installation state.

Embodiments of the invention

In Fig. 1 a high-pressure pump 1 for a fuel injection device of an internal combustion engine is shown. The high-pressure pump 1 has a housing 2, which is designed in several parts and in which a drive shaft 3 driven in rotation is arranged. The drive shaft 3 is rotatably supported in the housing 2 via two spaced apart in the direction of the axis of rotation 4 of the drive shaft 3 bearings. The bearings can be arranged in different housing parts 5, 6 of the housing 2.

In a region lying between the two bearing points, the drive shaft 3 has at least one cam 7 or eccentric, wherein the cam 7 can also be designed as a multiple cam. The high-pressure pump 1 has at least one or more arranged in each case 8 a housing part 8 pump elements 9, each with a pump piston 10 which is indirectly driven by the cam 7 of the drive shaft 3 in a lifting movement in at least approximately radial direction to the axis of rotation 4 of the drive shaft 3. The pump piston 10 is guided in a cylinder bore 11 in the housing part 8 tightly displaceable and limited with its drive shaft 3 facing away from the end face in the cylinder bore 11 a pump working chamber 12th

The pump working space 12 has a connection with a fuel feed, for example a feed pump, via a fuel feed channel 13 extending in the housing 2. At the mouth of the fuel inlet channel 13 in the pump chamber 12, an opening into the pump chamber 12 inlet valve 14 is arranged, which has a spring-loaded valve member 15. The pump working chamber 12 also has a connection extending in the housing part 8 fuel drain passage 16 to an outlet with an outlet, which is connected for example with a high-pressure accumulator 17. With the high-pressure accumulator 17 one or more preferably arranged on the cylinders of the internal combustion engine injectors 18 are connected, is injected through the fuel in the cylinder of the internal combustion engine. At the mouth of the fuel drain passage 16 in the pump chamber 12 is a from the pump working space 12th opening outlet valve 19 is arranged, which also has a spring-loaded valve member 20.

The pump element 9 is associated with a plunger assembly 21, via which the pump piston 10 is supported on the cam 7 of the drive shaft 3. The plunger assembly 21 includes a hollow cylindrical plunger body 22 which is slidably guided in a bore 23 of a portion 5 of the housing 2 of the high-pressure pump 1. The pump piston 10 has a smaller diameter than the plunger body 22 and protrudes with its pump chamber 12 facing away from the end of the cylinder bore 11 out and into the plunger body 22 into it. At its end remote from the pump working space 12, the pump piston 10 may have a piston foot 24 which is enlarged in diameter relative to its remaining area.

The plunger assembly 21 and the pump piston 10 are pressed by a prestressed spring 27 to the cam 7 of the drive shaft 3 out. The spring 27 is formed as the pump piston 10 surrounding and projecting into the plunger body 22 helical compression spring. The spring 27 is supported on the one hand on the pump housing part 8 and on the other hand on a spring plate 28 from.

Fig. 2 shows an in Fig. 1 marked with II section of the plunger assembly 21 of the high-pressure pump 1 of Fig. 1 according to the prior art. As can be seen in the figure, the spring plate 28 is connected to the pump piston 10 and is located on the side facing away from the roller shoe 26 of the annular web 29 at. The spring 27 thus acts on the spring plate 28 both on the pump piston 10 and on the plunger body 22nd

In the plunger body 22 of the drive shaft 3 side facing in the direction of the longitudinal axis 25 of the plunger body 22, a roller shoe 26 is inserted. In the roller shoe 26, a cylindrical roller 31 is rotatably mounted in a cylinder-section-shaped receptacle 30 on the cam 7 of the drive shaft 3 facing side of the roller shoe 26. The roller shoe 26 comes into abutment in the plunger body 22 in the direction of the longitudinal axis 25 against a stop 32 which is formed, for example, by a ring web projecting radially inwards from the plunger body 22.

FIGS. 3A, 3B, 3C each show a section of a plunger assembly 21 according to the prior art before, during and after the press-fitting process. FIGS. 4A, 4B, 4C each show a section of a plunger assembly 21 according to an embodiment before, during and after the press-fitting process, wherein the receptacle 30 of the plunger body 22 is provided with a centering guide to be described later.

Fig. 3A shows an initial stage before the actual press-in process, in which a small force K is applied vertically from above or in the Y direction on the plunger body 22 to bring this into abutment with the roller shoe 26. As compared with the corresponding initial stage, which in Fig. 4A with respect to one with a centering guide, which is related below Fig. 6 can be seen provided tappet body 22 is at a same in the Y direction on the plunger body 22 applied low force K of the roller shoe 26 already inserted into a first end portion 33 of the receptacle 30 of the plunger body 22. Already in this initial stage, a significantly higher pressing force or holding force is present between the plunger body 22 and the roller shoe 26 according to the embodiment than in the corresponding initial stage with respect to the plunger body 22 without centering and the roller shoe 26 according to the prior art.

Fig. 3B and Fig. 4B On the other hand, in each case, they show a state during the actual press-fitting process, in which a significantly higher force K of 6 kN in the Y-direction is applied to the tappet body 22. By applying the force K, for example, in the amount of 6 kN, the roller shoe 26 is inserted or pressed along an inner circumference 34 of the receptacle 30 of the plunger body 22 until the roller shoe 26 against the stop 32, which at a second end portion 35 of the receptacle 30 is provided, strikes. Finally, in Fig. 3C and 4C shown a state in which the roller shoe 26 has been pressed into the receptacle 30 of the plunger body 22 and no further force in the Y direction is exerted on the plunger body 22.

Fig. 5A again shows a detailed view of the in Fig. 3A illustrated initial stage, in which the plunger body 22 with the roller shoe 26 by low Force is brought into plant. A distance d between the stop 32 at the second end portion 35 of the receptacle 30 and the first end portion 33 is 11.8 mm. As in Fig. 5B is shown in the corresponding initial stage of the press-fitting operation of a roller shoe 26 in a provided with a centering tappet body 22 according to the embodiment (see Fig. 4A On the other hand, the distance d has already been reduced to 7.8 mm, with the same force K being applied to the tappet body 22 as in FIG Fig. 5A shown installation state.

Fig. 6 shows a more detailed view of the in Fig. 5B illustrated installation state. At the lower end portion 33 of the receptacle 30 of the plunger body 22, a centering guide 37 is formed on the inner periphery 34 over a height h of the receptacle 30 of 4 mm. The provided on the inner circumference 34 centering guide has a chamfer a of 0.05 mm and an angle of 45 °, which allows the roller shoe 26, already introduced during the initial stage on the height h of the centering guide 37 in the receptacle 30 to be (see Fig. 4A . 5B ).

Overall, by providing the centering guide 37, a robust plunger assembly 21 or a robust high-pressure pump 1 can be created. Due to the dimensions of the centering guide 37 causes no adverse weakening of the plunger body. Also, the behavior between the plunger body and the roller shoe with respect to the axial distance therebetween or with respect to the radial deformation of the plunger body in an initial stage, during Einpressvorgang itself or during the subsequent discharge is not adversely affected compared to a plunger body-roller shoe press assembly without centering according to the State of the art.

Claims (10)

1. High-pressure pump (1) for a fuel injection device of an internal combustion engine, which high-pressure pump has at least one pump element (9) with a pump piston (10) which delimits a pump working chamber (12), wherein a tappet assembly (21) having a tappet body (22) and having a roller shoe (26) pressed into a receptacle (30) of the tappet body (22) is provided between the pump piston (10) and a drive shaft (3), which is driven in rotation, of the high-pressure pump (1),
   characterized in that
   the tappet body (22) has a centering guide (37) for the pressing-in of the roller shoe (26).
2. High-pressure pump (1) according to Claim 1,
   characterized in that
   the centering guide (37) is provided in the region of the receptacle (30).
3. High-pressure pump according to Claim 1 or 2,
   characterized in that
   the receptacle (30) is formed in the shape of a segment of a cylinder, wherein the receptacle (30) has an inner circumference (34) on which the centering guide (37) is provided.
4. High-pressure pump (1) according to one or more of Claims 1 to 3,
   characterized in that
   the centering guide (37) has a bevel.
5. High-pressure pump (1) according to one or more of Claims 1 to 4,
   characterized in that
   the receptacle (30) has a first end section (33) and a second end section (35), wherein a stop (32) is provided on the second end section (35) so as to project radially inwardly from the inner circumference (34) of the latter, and wherein the first end section (33) faces an element of the drive shaft (3), in particular a cam (7) or an eccentric.
6. High-pressure pump (1) according to Claim 5,
   characterized in that
   the centering guide (37) is provided on the first end section (33).
7. High-pressure pump (1) according to Claim 5 or 6,
   characterized in that
   the centering guide (37) is provided over a height h of the first end section (33) in a range of 2 to 10 mm, in particular of 4 mm.
8. High-pressure pump (1) according to one or more of Claims 4 to 7,
   characterized in that
   the bevel has a depth a in a range of 0.1 to 0.01 mm, in particular a depth a of 0.05 mm, and is formed in an angle range from 30 to 60°, in particular with an angle of 45°.
9. High-pressure pump (1) according to one or more of Claims 1 to 8,
   characterized in that
   the roller shoe (26) is formed with a cylindrical interference fit oversize Pü,nenn, in particular with a cylindrical interference fit oversize Pü,nenn of 9 µm.
10. Tappet assembly (21) for a high-pressure pump (1) for a fuel injection device of an internal combustion engine, having a tappet body (22) and having a roller shoe (26) which is pressed into a receptacle (30) of the tappet body (22),
    characterized in that
    the tappet body (22) has a centering guide (37) for the pressing-in of the roller shoe (26).

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