WO2013113544A1

WO2013113544A1 - High-pressure pump

Info

Publication number: WO2013113544A1
Application number: PCT/EP2013/050629
Authority: WO
Inventors: Sascha ARMBROCK; Frank Zehnder
Original assignee: Robert Bosch Gmbh
Priority date: 2012-01-31
Filing date: 2013-01-15
Publication date: 2013-08-08
Also published as: EP2809943A1; CN104081038B; DE102012201302A1; CN104081038A; EP2809943B1

Abstract

The invention relates to a high-pressure pump (1) for conveying a fluid, particularly a fuel such as diesel, which comprises: a drive shaft (2) that has at least one cam (3); at least one piston (5); at least one cylinder (6) for mounting said at least one piston (5); and a roller shoe (9) that has a running roller (10) mounted therein (9) by means of a sliding bearing. The piston (5) is supported indirectly, using the roller shoe (9), on the drive shaft (2) with the at least one cam (3) such that said at least one piston (5) is able to carry out a translational movement on the basis of a rotational movement of the drive shaft (2), the sliding bearing on the roller shoe (9) comprising at least one recess outside of a sliding bearing operational contact surface.

Description

description

title

high pressure pump

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, especially in common-rail injection systems of diesel or gasoline engines, a high-pressure pump permanently 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 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 game or distance between the

Reduced roller and the sliding bearing on the roller shoe and thereby increases the friction or a clamping of the roller enters the roller shoe. In particular, the deposits occur outside one

Operating contact surface of the sliding bearing, so that thereby moves the roller within the roller shoe in the direction of the drive shaft.

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 by means of a plunger assembly in a bore of a

Part of the housing stored. The pump elements are at the

Tappet assembly attached. A coil spring presses the plunger assembly onto the cams. From DE 103 56 262 A1 is a radial piston pump for

High-pressure fuel production 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.

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 sliding bearing at least one

Recess has. Due to the at least recess, no deposits or deposits can occur on the at least one recess, which can cause jamming of the roller in the roller shoe or an increase in the friction of the roller. This can advantageously in a low technical effort, a jamming of the roller in the

Slide bearing of the roller shoe can be avoided.

In an additional embodiment, the at least one recess is formed as at least one axial groove and preferably the roller shoe on 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 recess, in particular 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. This occurs between the sliding bearing of the

Roller shoe and the roller a compressive force in the direction of

Translational movement of the roller shoe on. This pressure force is in

Substantially transferred to the operating contact surface of the roller shoe on the roller, so generally outside the

Operating contact surface no or only very small forces are transmitted from the roller shoe to the roller. The mounting aid is essentially required only that during the assembly of the high-pressure pump, the roller is fixed to the roller shoe and possibly used during operation of the

High pressure pump only to ensure 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 recess, in particular the at least one axial groove, interrupts the plain bearing in a tangential manner

Direction between the operating contact surface and the mounting aid of

Slide 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 completely continuous in the direction of

Rotation axis of the roller formed on the roller shoe. It is expedient for the at least one recess 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 at least 5 °, 10 ° or 15 °. The

Operating contact surface is thus at a portion of the sliding bearing in

Direction formed to 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 plain bearing or plain bearing on the mounting aid.

In a supplementary embodiment, the distance between the

Rotation axis of the roller and the sliding bearing of the roller shoe on the mounting aid larger than at the operating contact surface. In particular, the

Distance between the axis of rotation and the mounting aid to 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 sliding bearing, in particular the operating contact surface, with a coating, in particular

Carbon coating, provided to reduce 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 in the long-term and long-term operation of the coating only a very small and

having negligible ablation of the coating by the roller.

In a supplementary embodiment, the roller shoe is provided with at least one lubricating channel, which in the at least one recess,

in particular in the at least one axial groove, opens. By means of the

Lubrication channel can additionally fuel as a lubricant to the sliding bearing, in particular to the operating contact surface, are performed. 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. This can advantageously the formation of deposits and deposits on the

Slide bearing, especially at the operating contact surface, be significantly reduced.

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 inside one

Lubricating space arranged 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 through the

Lubrication channel passed to the at least one recess, thereby substantially increasing the lubrication of the sliding bearing of the roller shoe with fuel. In a supplementary embodiment, a sliding bearing between the

Roller shoe and the roller lubricated by 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, 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 on, which controls the regulated by the feed pump to the high pressure pump amount of fuel per unit time or regulates.

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 inventive internal combustion engine 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

Hereinafter, embodiments of the invention below

With reference to the accompanying drawings described in more detail. It 1 is a cross section of a high-pressure pump,

2 shows a section A-A according to FIG. 1 of a roller with roller shoe and a drive shaft from the prior art,

3 shows a section A-A of FIG. 1 of the roller with roller shoe in a first embodiment,

4 shows a section A-A according to FIG. 1 of the roller with roller shoe in a second exemplary embodiment,

Fig. 5 is a perspective view of the roller shoe of FIG. 3 and

Fig. 6 is a highly schematic view of a high-pressure injection system.

Embodiments of the invention

In Fig. 1 is a cross section of a high-pressure pump 1 for a

High-pressure injection system 36 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, a known from the prior art roller shoe 9 is 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 the drawing of FIG. 1 and is perpendicular to the

Drawing 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 so that only fuel can flow out of the working chamber 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

Rotation axis 25 lies in the plane of the drawing of FIG. 1 and is perpendicular to the plane of Fig. 2, 3 and 4. 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 1 1 on.

The roller tread 1 1 of the roller 10 rolls on the shaft rolling surface 4 of the drive shaft 2 with the two cams 3 at 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 a 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 is shown for a motor vehicle with a high-pressure rail 30 or a

Fuel rail 31 from the high-pressure rail 30, the fuel is injected by means of valves (not shown) in the combustion chamber of the engine 39. A prefeed pump 35 delivers fuel from one

Fuel tank 32 through a fuel line 33 to the high-pressure pump 1 according to the above embodiment. The high-pressure pump 1 and the

Pre-feed 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 through the fuel line 33 to the

High-pressure pump 1 passed. The one not required by the high-pressure pump 1 Fuel is thereby through a fuel return line 34 back into the

Fuel tank 32 returned. 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 at the operating contact surface 14 is a

Carbon coating 41 formed 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 is incorporated between the operating contact surface 14 and the carbon coating 41 and the two mounting aids 15 a semi-circular in cross-section axial groove 17 in the roller shoe 9 made of steel. 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. In normal operation of the high-pressure pump 1, the roller shoe 9 leads to the roller 10 a

oscillating translational 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. In normal operation of the high-pressure pump thus occurs only at the

Operating contact surface 14 on a contact between the roller shoe 9 and the roller 10. The two assembly aids 15 as part of the sliding bearing

13 are required only during assembly of the high-pressure pump 1 to the

To be able to keep roller 10 in the roller shoe 9. In addition, even during normal operation of the high pressure pump 1 vibrations of

High-pressure pump 1 occur, which could cause falling out of the roller 10 in very unfavorable circumstances. In this extraordinary

Operating conditions of the high-pressure pump 1, the two mounting aids 15th the plain bearing 13 is required to in this operating condition of

High pressure pump 1 with vibrations, the roller 10 securely on the

To be able to hold roller shoe 9.

The operating contact surface 14 and the sliding bearing 13 has in the section in Fig. 3, a point 38 with a minimum distance to the piston 5 and in the section in Fig. 3 is at the point 38 to a point, but due the extension 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. 3 and this

Halfway also cuts the point 38. The two angles ß are limited in two opposite directions of the fictitious half-line 45. The two angles ß in Fig. 3 are about 30 °, so that a

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. On 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. 5). 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 by the Lubrication channels 42 led to the axial grooves 17 fuel and thereby the operating contact surface 14 is surrounded with additional fuel or

lubricated, so that thereby the temperature of the operating contact surface 14 is reduced due to the cooling effect of the fuel and thus less deposits or deposits form on the operating contact surface 14 and the mounting aid 15. Optionally, in another not shown

Embodiment of the roller shoe 9 be executed without the lubrication channels 42.

The two axial grooves 17 in the first embodiment of the

Roller shoe 9 of 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. This forms in a known from the prior art

Roller shoe 9 also in this area a coating or a deposit, because in general on the operating contact surface 14 due to the constant contact between the roller 10 and the operating contact surface 14 generally no

Deposits are formed. 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

FIGS. 3 and 5 may form deposits or deposits essentially only on the assembly aid 15. In this case, 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 1 1 and of the

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 in the roller shoe 9 occurs. In addition, as already mentioned, at the operating contact surface 14, as a rule, no or no

Essentially no deposits on and due to the axial groove 17 is a movement due to deposits of the roller 10 relative to the

Roller shoe 9 excluded in the direction of the drive shaft 2. 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

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

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 14.

Claims

High-pressure pump (1) for conveying a fluid, in particular fuel, e.g. B. Diesel, comprehensive

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

- at least one piston (5),

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

- a roller shoe (9) with a roller (10) mounted in the roller shoe (9) with a sliding bearing (13) and the piston (5) is indirectly connected to the roller shoe (9) on the drive shaft (2) with the at least one cam (3) is supported, so that a translational movement is caused by the at least one piston (5) due to a

Rotational movement of the drive shaft

(2) can be carried out, characterized in that the sliding bearing (13) on the roller shoe (9) outside one

Operating contact surface (14) of the sliding bearing (13) has at least one recess (16).

High-pressure pump according to claim 1, characterized in that the at least one recess (16) is designed as at least one axial groove (17) and preferably the roller shoe (9) has two axial grooves (17).

and or

at the at least one recess (16), in particular the at least one axial groove (17), no contact between the roller (10) and the Roller shoe (9) exists.

3. High pressure pump according to one or more of the previous ones

Claims, characterized in that the at least one recess (16), in particular the at least one axial groove (17), in the tangential direction (18) between the

Operating contact surface (13) and an assembly aid (15) of the plain bearing (13) is formed.

4. High pressure pump according to one or more of the previous ones

Claims, characterized in that the at least one recess (16), in particular the at least one axial groove (17), the sliding bearing (13) in the tangential direction (18) between the operating contact surface (14) and the assembly aid (15) of the sliding bearing ( 13) interrupts

and or

the at least one axial groove (17) is formed completely in the axial direction of an axis of rotation (25) of the roller (10) on the roller shoe (9).

5. High pressure pump according to one or more of the previous ones

Claims, characterized in that the assembly aid (15) of the sliding bearing (13) in the direction (43) of

Translational movement of the roller shoe (9) is at least partially formed between the axis of rotation (25) of the roller (10) and one side (44) of the roller shoe (9) in the direction of the drive shaft (2). High-pressure pump according to one or more of the preceding claims, characterized in that the operating contact surface (13) has an angular range in a fictitious plane perpendicular to the axis of rotation (25) of the roller (10), each starting with opposite angles on a fictitious half-line (45). the point (38) of the operating contact surface (14) with a minimum distance to the piston (5) and the axis of rotation (25) of the roller (10) intersects, of less than 80°, 60°, 40°, 30°, 15° , 10° or 5° and/or comprises at least 5°, 10° or 15°.

High-pressure pump according to one or more of the preceding claims, characterized in that the distance between the axis of rotation (25) of the roller (10) and the sliding bearing (13) of the roller shoe (9) on the assembly aid (15) is greater than on the operating contact surface ( 14).

High-pressure pump according to one or more of the preceding claims, characterized in that the sliding bearing (13), in particular the operating contact surface (14), with a coating (40), in particular carbon coating (41), to reduce the friction between the roller (10) and the

Plain bearing (13) is provided.

High-pressure pump according to one or more of the preceding claims, characterized in that the roller shoe (9) is provided with at least one lubrication channel (42) which opens into the at least one recess (16), in particular into the at least one axial groove (17).

0. High-pressure pump according to claim 9, characterized in that the at least one lubrication channel (42) in the direction (43) of

Translational movement of the roller shoe (9) is formed and preferably the at least one lubrication channel (42) ends on one side (44) of the roller shoe (9) in the direction of the drive shaft (2).

1. High pressure pump according to one or more of the previous ones

Claims, characterized in that a sliding bearing (13) between the roller shoe (8) and the roller (10) is lubricated by fuel.

2. High-pressure injection system (36) for an internal combustion engine (39), comprising

- a high-pressure pump (1),

- a high-pressure rail (30),

- Preferably a pre-feed pump (35) for feeding 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.