EP2809943B1 - High-pressure pump - Google Patents

Description

The present invention relates to a high pressure pump according to the preamble of claim 1 and a high pressure injection system according to the preamble of claim 12.

State of the art

In high-pressure injection systems for internal combustion engines, in particular in common-rail injection systems of diesel or gasoline engines, a high-pressure pump continuously ensures the maintenance of the pressure in the high-pressure accumulator of the common-rail injection system. The high-pressure pump can be driven, for example, by a camshaft of the internal combustion engine by means of a drive shaft. For the promotion of the fuel to the high-pressure pump Vorförderpumpen, z. B. a gear or rotary vane pump used, which are connected upstream of the high-pressure pump. The prefeed pump delivers the fuel from a fuel tank through a fuel line to the high pressure pump.

Amongst others, piston pumps are used as high-pressure pumps. In a housing, a drive shaft is mounted. Radially to pistons are arranged in a cylinder. On the drive shaft with at least one cam is a roller with a roller rolling surface, which is mounted in a roller shoe. The roller shoe is connected to the piston, so that the piston is forced to oscillate translational motion. A spring applies to the roller shoe a radially directed to the drive shaft force, so that the roller is in constant contact with the drive shaft. The roller stands with the roller rolling surface on a shaft rolling surface as the surface of the drive shaft with the at least one cam in contact with the drive shaft. The roller is mounted by means of a sliding bearing in the roller shoe. At the sliding bearing of the roller shoe occur deposits or occurs a deposit formation, z. B. due to cracked fuel with which the slide bearing is lubricated. The deposits cause the clearance or clearance between the roller and the slide bearing on the roller shoe to be reduced, thereby increasing the friction or causing the roller to jam in the roller shoe. In particular, the deposits occur outside of an operating contact surface of the sliding bearing, so that thereby moves the roller within the roller shoe in the direction of the drive shaft.
The DE 10 2006 045 933 A1 shows a high-pressure pump for high-pressure fuel delivery. The high-pressure pump has a drive shaft with cams. Cylindrical rollers are supported by roller shoes and rest on the cams. The roller shoes are mounted by means of a plunger assembly in a bore of a part of the housing. The pump elements are attached to the plunger assembly. A coil spring presses the plunger assembly onto the cams.
From the DE 103 56 262 A1 is a radial piston pump for fuel high pressure generation in fuel injection systems of internal combustion engines known. In a pump housing, a drive shaft is mounted. Pistons are supported on the drive shaft, so that by rotating the drive shaft, the pistons are moved back and forth. Between the piston and the drive shaft tappets are arranged.

The DE 10 2009 028 378 A1 is considered to be the closest prior art and discloses a friction-reduced coated roller shoe having a widening gap between roller and roller shoe over the operating contact surface. A cover prevents the ingress of dirt into the gap.

Disclosure of the invention Advantages of the invention

Inventive high-pressure pump, in particular for a motor vehicle, for conveying a fluid, in particular fuel, for. B. diesel, comprising a drive shaft with at least one cam, at least one piston, at least one cylinder for supporting the at least one piston, a roller shoe with a mounted in the roller shoe with a sliding bearing Roller and the piston indirectly with the roller shoe on the drive shaft with the at least one cam is supported, so that from the at least one piston a translational movement due to a rotational movement of the drive shaft executable, wherein the sliding bearing on the roller shoe outside an operating contact surface of the slide bearing at least one recess has at least one axial groove and the at least one axial groove is formed completely in the axial direction of a rotation axis of the roller on the roller shoe. having. Due to the at least one axial groove, no deposits or deposits can occur on the at least one axial groove, which can cause jamming of the roller in the roller shoe or an increase in the friction of the roller. As a result, it is advantageously possible to avoid jamming of the roller in the plain bearing of the roller shoe with little technical effort. According to the invention, the at least one recess is formed as at least one axial groove and preferably the roller shoe has two axial grooves and / or there is at the at least one recess, in particular the at least one axial groove, no contact between the roller and the roller shoe. An axial groove on the roller shoe allows the clamping to be prevented over a larger area of the roller shoe in the direction of the axis of rotation of the roller.

In a supplementary embodiment, the at least one axial groove is formed in the tangential direction between the operating contact surface and an assembly aid of the plain bearing. During operation of the high-pressure pump, the roller shoe is pressed by a spring onto the drive shaft. As a result, a compressive force occurs in the direction of the translational movement of the roller shoe between the plain bearing of the roller shoe and the roller. This pressure force is transmitted to the roller substantially at the operating contact surface of the roller shoe, so that in general no or only very small forces are to be transmitted from the roller shoe to the roller outside of the operating contact surface. The mounting aid is essentially required only that during the assembly of the high-pressure pump, the roller is attached to the roller shoe and possibly used during operation of the high-pressure pump only that in case of disturbances or vibrations, the roller is still held on the roller shoe. However, generally occurs at the Assembly aid in normal operation of the high pressure pump no contact between the roller and the mounting aid of the sliding bearing on.

In a supplementary variant, the at least one axial groove interrupts the sliding bearing in the tangential direction between the operating contact surface and the mounting aid of the plain bearing and / or the at least one axial groove is formed completely in the axial direction of a rotation axis of the roller on the roller shoe. In a complete embodiment of the at least one axial groove on the roller shoe, the axial groove is formed completely continuously in the direction of the axis of rotation of the roller on the roller shoe. It is expedient for the at least one axial groove to have a spacing of at least 0.5, 1, 2, 3 or 5 mm between the roller shoe and the roller rolling surface of the roller.
In an additional embodiment, the mounting aid of the plain bearing in the direction of the translational movement of the roller shoe is at least partially formed between the axis of rotation of the roller and a side of the roller shoe in the direction of the drive shaft.
Suitably, the operating contact surface comprises an angular range in a fictitious plane perpendicular to the axis of rotation of the caster, each beginning at opposite angles on a fictitious half-line intersecting the location of the operating contact surface with a minimum distance to the piston and the axis of rotation of the caster of less than 80 ° , 60 °, 40 °, 30 °, 15 °, 10 ° or 5 ° and / or of at least 5 °, 10 ° or 15 °. The operating contact surface is thus formed at a portion of the sliding bearing in the direction of the piston, that is, the operating contact surface has a smaller distance to the piston than the rest of sliding bearing. In particular, the rest of the sliding bearing of the roller shoe comprises only the mounting aid of the plain bearing or the sliding bearing on the mounting aid.
In a supplementary embodiment, the distance between the axis of rotation of the roller and the sliding bearing of the roller shoe on the mounting aid is greater than on the operating contact surface. In particular, the distance between the axis of rotation and the mounting aid is at least 1, 3, 5, 10, 20 or 30% greater than the distance between the axis of rotation and the operating contact surface.
In a further embodiment, the plain bearing, in particular the operating contact surface, is provided with a coating, in particular carbon coating, for reducing the friction between the roller and the plain bearing. The coating reduces the friction between the roller and the slide bearing on the operating contact surface and is also abrasion resistant, so that the high pressure pump has only a very small and negligible removal of the coating by the roller in permanent and long-term operation on the coating.
In a supplementary embodiment, the roller shoe is provided with at least one lubrication channel, which opens into the at least one recess, in particular into the at least one axial groove. By means of the lubricating channel, fuel can additionally be conducted as lubricant to the slide bearing, in particular to the operating contact surface. Thereby, the temperature of the sliding bearing of the roller shoe is reduced due to the friction occurring because heat is dissipated by the fuel. As a result, the formation of deposits and deposits on the slide bearing, in particular on the operating contact surface, can be substantially reduced in an advantageous manner.
In an additional variant, the at least one lubrication channel is designed in the direction of the translational movement of the roller shoe, and preferably the at least one lubrication channel terminates on one side of the roller shoe in the direction of the drive shaft. The roller shoe is arranged within a lubricant space with fuel and in a translational movement of the piston from a top dead center to a bottom dead center thereby flows fuel into the lubrication channel and is then passed through the lubrication channel to the at least one axial groove, thereby lubricating the plain bearing of the roller shoe with fuel is substantially increased.
In a supplementary embodiment, a sliding bearing between the roller shoe and the roller is lubricated by means of fuel.

Expediently, the high-pressure pump comprises a lubricating space and fuel is conveyed through the lubricating space for lubricating the high-pressure pump and within the lubricating space the roller shoe with the roller and preferably the drive shaft and partially preferably the piston is arranged.

In a further variant, an eccentric shaft is considered as a drive shaft with at least one cam.

Inventive high-pressure injection system for an internal combustion engine, in particular for a motor vehicle, comprising a high pressure pump, a high pressure rail, preferably a prefeed pump for conveying a fuel from a fuel tank to the high pressure pump, wherein the high pressure pump is designed as a high pressure pump described in this patent application.

In a further variant, the high-pressure injection system has a metering unit which controls or regulates the quantity of fuel delivered per unit time by the prefeed pump to the high-pressure pump.

The producible by the high-pressure pump pressure in the high-pressure rail is, for example, in the range of 1000 to 3000 bar z. B. for diesel engines or between 40 bar and 400 bar z. B. for gasoline engines.

An internal combustion engine according to the invention with a high-pressure injection system, in particular for a motor vehicle, comprises a high-pressure injection system described in this patent application and / or a high-pressure pump described in this patent application.

Brief description of the drawings

Fig. 1

einen Querschnitt einer Hochdruckpumpe,

Fig. 2

einen Schnitt A-A gemäß Fig. 1 einer Laufrolle mit Rollenschuh und einer Antriebswelle aus dem Stand der Technik,

Fig. 3

einen Schnitt A-A gemäß Fig. 1 der Laufrolle mit Rollenschuh in einem ersten Ausführungsbeispiel,

Fig. 4

einen Schnitt A-A gemäß Fig. 1 der Laufrolle mit Rollenschuh in einem zweiten Ausführungsbeispiel,

Fig. 5

eine perspektivische Ansicht des Rollenschuhes gemäß Fig. 3 und

Fig. 6

eine stark schematisierte Ansicht eines Hochdruckeinspritzsystems.

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

Fig. 1

a cross section of a high pressure pump,

Fig. 2

a section AA according to Fig. 1 a roller with roller shoe and a drive shaft from the prior art,

Fig. 3

a section AA according to Fig. 1 the roller with roller shoe in a first embodiment,

Fig. 4

a section AA according to Fig. 1 the roller with roller shoe in a second embodiment,

Fig. 5

a perspective view of the roller shoe according to Fig. 3 and

Fig. 6

a highly schematic view of a high-pressure injection system.

Embodiments of the invention

In Fig. 1 a cross section of a high pressure pump 1 for a high pressure injection system 36 is shown. The high-pressure pump 1 serves to fuel, z. As gasoline or diesel, to promote an internal combustion engine 39 under high pressure. The pressure which can be generated by the high-pressure pump 1 is, for example, in a range between 1000 and 3000 bar. In Fig. 2 is a known from the prior art roller shoe 9 shown.

The high-pressure pump 1 has a drive shaft 2 with two cams 3, which performs a rotational movement about a rotation axis 26. The axis of rotation 26 lies in the plane of Fig. 1 and is perpendicular to the plane of Fig. 2 , A piston 5 is mounted in a cylinder 6, which is formed by a housing 8. A working chamber 29 is bounded by the cylinder 6, the housing 8 and the piston 5. Into the working space 29 opens an inlet channel 22 with an inlet valve 19 and an outlet channel 24 with an outlet valve 20. Through the inlet channel 22, the fuel flows into the working space 29 and through the outlet channel 24, the fuel flows out of the working space 29 under high pressure. The inlet valve 19, z. As a check valve, is designed such that only fuel in the Working space 29 can flow and the exhaust valve 20, z. B. a check valve is designed to the effect that only fuel can flow out of the working space 29. The volume of the working chamber 29 is changed due to an oscillating stroke movement of the piston 5. The piston 5 is indirectly supported on the drive shaft 2 from. At the end of the piston 5 or pump piston 5, a roller shoe 9 is attached to a roller 10. The roller 10 can perform a rotational movement, the axis of rotation 25 in the plane according to Fig. 1 lies and perpendicular to the plane of Fig. 2 . 3 and 4 stands. The drive shaft 2 with the at least one cam 3 has a shaft rolling surface 4 and the roller 10 has a roller rolling surface 11.

The roller running surface 11 of the roller 10 rolls on the shaft rolling surface 4 of the drive shaft 2 with the two cams 3 on a contact surface 12 from. The roller shoe 9 is mounted in a roller shoe bearing formed by the housing 8 as a slide bearing 13. In Fig. 2 is a well-known from the prior art slide bearing 13 is shown. A spring 27 or spiral spring 27 as an elastic element 28, which is clamped between the housing 8 and the roller shoe 9, applies a compressive force to the roller shoe 9, so that the roller rolling surface 11 of the roller 10 is in constant contact with the shaft roller 9. Rolling surface 4 of the drive shaft 2 is. The roller shoe 9 and the piston 5 thus carry out together an oscillating stroke movement.

In Fig. 6 is a highly schematic representation of the high-pressure injection system 36 shown for a motor vehicle with a high-pressure rail 30 or a fuel rail 31. From the high-pressure rail 30 of the fuel by means of valves (not shown) is injected into the combustion chamber of the engine 39. A prefeed pump 35 delivers fuel from a fuel tank 32 through a fuel pipe 33 to the high-pressure pump 1 according to the above embodiment. The high-pressure pump 1 and the prefeed pump 35 are driven by the drive shaft 2. The drive shaft 2 is coupled to a crankshaft of the engine 39. The high pressure rail 30 serves - as already described - to inject the fuel into the combustion chamber of the internal combustion engine 39. The funded by the feed pump 35 fuel is passed through the fuel line 33 to the high-pressure pump 1. The one not required by the high-pressure pump 1 Fuel is returned through a fuel return line 34 back into the fuel tank 32. A metering unit 37 controls and / or regulates the quantity of fuel supplied to the high-pressure pump 1, so that the fuel return line 34 can be dispensed with in a further embodiment (not shown).

In Fig. 3 and 5 a first embodiment of the roller shoe 9 is shown with the roller 10 for a high-pressure pump 1 according to the invention. The sliding bearing 13 of the roller shoe 9 comprises an operating contact surface 14 and an assembly aid 15. Only on the operating contact surface 14 is a carbon coating 41 formed as a coating 40 is present. Outside the carbon coating 41, the roller shoe 9 is made of metal, for example steel, such as the roller 10. At the mounting aid 15, the sliding bearing 13 no carbon coating 41 on. In a tangential direction 18 of the sliding bearing 13, a cross-sectionally semicircular axial groove 17 is incorporated in the roller shoe 9 made of steel between the operating contact surface 14 and the carbon coating 41 and the two mounting aids. The two axial grooves 17 between the operating contact surface 14 and the two mounting aids 15 thus form a recess 16 on the sliding bearing 13, so that no contact between the roller shoe 9 and the roller 10 can occur at the two axial grooves 17. During normal operation of the high-pressure pump 1, the roller shoe 9 with the roller 10 performs an oscillating translatory movement in one direction 43. In this case, a compressive force in the direction of the drive shaft 2 is applied by the spring 27 on the roller shoe 9, so that from the roller shoe 9 on the roller 10, a compressive force is transmitted and this is exclusively or substantially at the operating contact surface 14 of the roller shoe on the Transfer roller 10. During normal operation of the high-pressure pump, contact only occurs between the roller shoe 9 and the roller 10 at the operating contact surface 14. The two assembly aids 15 as part of the sliding bearing 13 are required only during assembly of the high pressure pump 1 to hold the roller 10 in the roller shoe 9 can. In addition, vibrations of the high pressure pump 1 may also occur during normal operation of the high pressure pump 1, which could cause falling out of the roller 10 in very unfavorable circumstances. In these exceptional operating conditions of the high-pressure pump 1, the two mounting aids 15 the slide bearing 13 is required in order to be able to hold the roller 10 securely against the roller shoe 9 even with vibrations in this operating state of the high-pressure pump 1.

The operating contact surface 14 or the sliding bearing 13 has in the section in Fig. 3 a location 38 with a minimum distance to the piston 5 on and in the section in FIG Fig. 3 is the point 38 to a point, but due to the expansion of the roller shoe 9 and the roller 10 perpendicular to the plane of Fig. 3 the point 38 is a line or a straight line. A first leg of the angle β is a fictitious half-line 45, beginning with the axis of rotation 25 in the section in FIG Fig. 3 and this half-line also intersects the point 38. The two angles β are bounded in two opposite directions by the fictitious half-line 45. The two angles β are in Fig. 3 about 30 °, so that an angular range α of the operating contact surface 14 is approximately equal to 60 °. A sufficiently large angular range α of the operating contact surface 14 is required so that the running roller 9 is sufficiently supported by the operating contact surface 14 of the roller shoe 9 during normal operation. At a lower side or a side 44 of the roller shoe 9 in the direction of the drive shaft 2, the roller shoe 9 has a total of four lubrication channels 42 (FIG. Fig. 5 ) on. These lubrication channels 42 begin at the side 44 and respectively end and guide into the two axial grooves 17. In each case two lubrication channels 42 open into each of the two axial grooves 17. In the oscillating translational movement of the roller shoe 9 within the lubricating space with fuel is characterized the lubricating passages 42 guide fuel to the axial grooves 17 and thereby the operating contact surface 14 is lubricated with additional fuel so that thereby the temperature of the operating contact surface 14 is reduced due to the cooling effect of the fuel and thus form less deposits on the operating contact surface 14 as well as on the mounting aid 15. Optionally, in another embodiment, not shown, the roller shoe 9 may be executed without the lubrication channels 42.

The two axial grooves 17 in the first embodiment of the roller shoe 9 according to Fig. 3 and 5 have significant advantages for the high pressure pump 1. In one known from the prior art Roller shoe 9 ( Fig. 2 ), the slide bearing 13 on no axial grooves 17. As a result, in the case of a roller shoe 9 known from the prior art, there is also a deposit or deposit in this area, because generally no deposits are formed on the operating contact surface 14 due to the permanent contact between the roller 10 and the operating contact surface 14. In the prior art, this leads to the fact that deposits on the slide bearing 13 outside the operating contact surface 14 causes a movement of the roller 10 in the direction of the drive shaft 2 and this leads in the long-term operation of the high-pressure pump 1 to a clamping of the roller 10 within the slide bearing 13 , In the roller shoe 9 according to Fig. 3 and 5 Deposits or deposits can essentially only form on the assembly aid 15. However, the mounting aid 15, since it is not required in normal operation for the sliding bearing of the roller 10, formed with a significantly greater distance of the rotation axis 25 of the roller 9, so that between the roller 10 and the roller rolling surface 11 and Mounting aid 15 is a very large distance or a very big game and this distance and this game is chosen so constructive that even with unfavorable and larger deposits on the mounting aid 15 no clamping of the roller 10 occurs in the roller shoe 9. In addition, as already mentioned, no or substantially no deposits occur on the operating contact surface 14, and because of the axial groove 17, movement due to deposits of the roller 10 relative to the roller shoe 9 in the direction of the drive shaft 2 is precluded. The axial grooves 17 thus prevent a relative movement of the roller 10 relative to the roller shoe 9 in the direction of the drive shaft second

In Fig. 4 a second embodiment of the roller shoe 9 is shown. In the following, essentially only the differences from the first embodiment will be according to FIG Fig. 3 and 5 described. The two axial grooves 17 are in the section in Fig. 4 formed substantially rectangular and not semicircular. Otherwise, the roller shoe 9 corresponds to Fig. 4 the in Fig. 3 and 5 shown first embodiment of the roller shoe. 9

Overall, significant advantages are associated with the high-pressure pump 1 according to the invention. The two axial grooves 17 prevent as simple and inexpensive constructive feature a relative movement of the roller 10 relative to the roller shoe 9 in the direction of the drive shaft 2, thereby clamping the roller 10 can be prevented in the roller shoe 9, because between the two mounting aids 15 and the roller 10 constructively a large Distance and a big game exists. In addition, possibly occurring deposits or deposits on the mounting aid 15 as part of the sliding bearing 13 does not lead to a clamping of the roller 10, because constructively between the roller 10 and the mounting aid 15, a sufficiently large distance or a sufficiently large game exists, for example between 0.2 and 2 mm at a contact of the roller 10 with the operating contact surface fourteenth

Claims (12)

1. High-pressure pump (1) for delivering a fluid, in particular fuel, for example diesel, comprising

   - a drive shaft (2) with at least one cam (3),

   - at least one piston (5),

   - at least one cylinder (6) for the mounting of the at least one piston (5),

   - a roller shoe (9) with a roller (10) mounted in the roller shoe (9) with a plain bearing arrangement (13) as operating contact surface (14), and the piston (5) is supported indirectly by means of the roller shoe (9) on the drive shaft (2) with the at least one cam (3), such that the at least one piston (5) can perform a translational movement owing to a rotational movement of the drive shaft (2),

   characterized in that
   the plain bearing arrangement (13) on the roller shoe (9) has, outside the operating contact surface (14) of the plain bearing arrangement (13), at least one recess (16) as at least one axial groove (17), and the at least one axial groove (17) is formed entirely in an axial direction of an axis of rotation (25) of the roller (10) on the roller shoe (9).
2. High-pressure pump according to Claim 1,
   characterized in that
   at the at least one axial groove (17), there is no contact between the roller (10) and the roller shoe (9).
3. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the at least one axial groove (17) is formed in a tangential direction (18) between the operating contact surface (13) and an installation aid (15) of the plain bearing arrangement (13).
4. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the at least one axial groove (17) interrupts the plain bearing arrangement (13) in a tangential direction (18) between the operating contact surface (14) and the installation aid (15) of the plain bearing arrangement (13).
5. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the installation aid (15) of the plain bearing arrangement (13) is, in a direction (43) of the translational movement of the roller shoe (9), formed at least partially between the axis of rotation (25) of the roller (10) and a side (44) of the roller shoe (9) in a direction towards the drive shaft (2).
6. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the operating contact surface (13) encompasses an angle range of less than 80°, 60°, 40°, 30°, 15°, 10° or 5°, and/or of at least 5°, 10° or 15°, in an imaginary plane perpendicular to the axis of rotation (25) of the roller (10) in each case beginning with opposite angles at an imaginary half line (45) which intersects the point (38) of the operating contact surface (14) with a minimum spacing to the piston (5) and the axis of rotation (25) of the roller (10).
7. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the spacing between the axis of rotation (25) of the roller (10) and the plain bearing arrangement (13) of the roller shoe (9) is greater at the installation aid (15) than at the operating contact surface (14).
8. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the plain bearing arrangement (13), in particular the operating contact surface (14), is equipped with a coating (40), in particular carbon coating (41), for reducing the friction between the roller (10) and the plain bearing arrangement (13).
9. High-pressure pump according to one or more of the preceding claims,
   characterized in that
   the roller shoe (9) is equipped with at least one lubricating duct (42) which opens into the at least one axial groove (17).
10. High-pressure pump according to Claim 9,
    characterized in that
    the at least one lubricating duct (42) is formed in a direction (43) of the translational movement of the roller shoe (9), and preferably, the at least one lubricating duct (42) ends at a side (44) of the roller shoe (9) in a direction towards the drive shaft (2).
11. High-pressure pump according to one or more of the preceding claims,
    characterized in that
    a plain bearing arrangement (13) between the roller shoe (8) and the roller (10) is lubricated by means of fuel.
12. High-pressure injection system (36) for an internal combustion engine (39), comprising

    - a high-pressure pump (1),

    - a high-pressure rail (30),

    - preferably a predelivery pump (35) for delivering a fuel from a fuel tank (32) to the high-pressure pump (1),

    characterized in that
    the high-pressure pump (1) is designed as a high-pressure pump (1) according to one or more of the preceding claims.

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