WO2012072294A1

WO2012072294A1 - High-pressure pump

Info

Publication number: WO2012072294A1
Application number: PCT/EP2011/066398
Authority: WO
Inventors: Werner Vallon; Andreas Dutt; Dietmar Ottenbacher; Matthias Greiner; Gerhard Meier; Jochen Aleker; Dietmar Schorr
Original assignee: Robert Bosch Gmbh
Priority date: 2010-11-30
Filing date: 2011-09-21
Publication date: 2012-06-07
Also published as: DE102010062159A1

Abstract

A high-pressure pump (1), in particular for a motor vehicle (38), for delivering a fluid, in particular fuel, for example diesel, comprising a drive shaft (2) having at least one cam (3), at least one piston (5), and at least one cylinder (6) for mounting the at least one piston (5), wherein the at least one piston (5) is supported indirectly via at least one running roller (10) with a roller rolling surface (11) on a shaft rolling surface (4) of the drive shaft (2) with the at least one cam (3), such that the at least one piston (5) can perform a translatory movement owing to the rotational movement of the drive shaft (2), wherein the shaft rolling surface (4) and/or the roller rolling surface (11) are/is provided with grooves (40) for increasing the roughness of the shaft rolling surface (4) and/or of the roller rolling surface (11).

Description

description

title

high pressure pump

The present invention relates to a high-pressure pump according to the preamble of claim 1, a high-pressure injection system according to the preamble of claim 12 and an internal combustion engine according to the preamble of claim 14.

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 is available the roller rolling surface on a shaft rolling surface of the drive shaft in contact with the drive shaft. The roller is mounted by means of a sliding bearing in the roller shoe. The rolling friction between the roller rolling surface and the shaft rolling surface, especially at low loads or low speeds or during the starting process of the high-pressure pump, under the sliding friction between the roller in the roller shoe drop, so that the roller no

Performs rotational movement or has only a small angular velocity. This leads disadvantageously to high with respect to the drive shaft tangential forces in the roller and thus in the roller shoe and a bearing of the roller shoe, so that it can cause damage and increased wear. In particular, the ever-increasing pressures required in diesel engines increase the mechanical

Charges.

From US 2010/0037864 A1 a high-pressure pump with an eccentric shaft or drive shaft with a cam is known. The high pressure pump serves to deliver fuel for a diesel engine. Due to the

Rotary movement of the drive shaft with the at least one cam and an indirect support of a piston on the drive shaft, the piston performs an oscillating movement for pumping the fuel. In this case, a cam outlet on the drive shaft has a greater roughness than a cam run-up.

US 2007/0071622 A1 shows a high-pressure pump for conveying fuel for internal combustion engines. On an eccentric shaft three pistons are indirectly mounted by means of a roller shoe and a roller. In this case, a roller rolling surface of the roller on a different roughness.

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, wherein the at least one piston is indirectly supported by means of at least one roller with a roller rolling surface on a shaft rolling surface of the drive shaft with the at least one cam, so that from the at least one piston a translational movement due to a rotational movement of the drive shaft is executable, wherein the shaft Rolling surface and / or the roller rolling surface with

Grooves to increase the roughness of the shaft roller surface and / or the roller rolling surface are provided.

As a result, essentially no play or slippage occurs during the rotational movement on the contact surface between the shaft rolling surface and the roller rolling surface. The roller performs a constant

Rotational movement out according to the rotational movement of the

Drive shaft. At a roller skating a roller shoe on the housing of the high-pressure pump thus occurs a uniform and constant load. Load peaks and high wear due to missing or low

Rotation of the roller can thus be avoided in an advantageous manner.

The slip, that is, a relative sliding movement between the roller and the shaft rolling surface of the drive shaft, thereby substantially be excluded, so that when a start operation of the high-pressure pump when the drive shaft of the high-pressure pump is set in a rotational movement, substantially no slip occurs. This can reduce the wear or damage caused by slippage between the roller and the

Drive shaft can be avoided. The rolling friction forces between the at least one roller and the drive shaft are thus, in particular in the operating state of the starting process, greater than the sliding friction between the roller and a roller shoe on a sliding bearing of the roller on the roller shoe.

In an additional embodiment, the grooves are rectilinear or curved.

In a supplementary variant, the shaft rolling surface and / or the roller rolling surface consists at least partially, in particular completely, of steel

and / or the shaft rolling surface and / or the roller rolling surface is only partial, in particular in the direction of a running direction, provided with grooves, so that the roughness of the wave rolling surface and / or the roller rolling surface outside the grooves is smaller than at the grooves. The roughness of the shaft rolling surface and / or the roller rolling surface at the grooves corresponds to the depth of the grooves and the roughness of the wave rolling surface and / or the roller rolling surface outside the

Grooves or a groove area corresponds to the depth of the roughness outside the groove area.

In a supplementary embodiment, the grooves have a depth in the range between 1 and 20 μιη, in particular between 2 and 10 μιη, on.

In a further embodiment, the grooves, in particular rectilinear, are aligned substantially in the direction of the running direction. Aligned substantially in the direction of the running direction means that the direction of the grooves are aligned with a deviation of less than 30 °, 20 °, 10 ° or 5 ° in the direction or parallel to the running direction. For grooves, which have a curvature and the curvature thereby runs serpentine, the direction of the serpentine grooves corresponds to the overall course of a

serpentine groove.

Suitably, the grooves are formed only on the shaft rolling surface.

In an additional embodiment, the grooves are formed on the shaft tread only on at least one section in the direction of travel.

In an additional variant, the grooves on the at least one

Subsection formed in the running direction before a bottom dead center on a cam outlet of the drive shaft with the at least one cam. At the cam outlet of the drive shaft before or shortly before the bottom dead center, the lowest pressure forces between the roller and the drive shaft occur.

As a result, in particular in this state or in this position of the high-pressure pump, in particular during a starting process, the risk of slippage between the roller and the drive shaft due to a lack or too low rotational movement of the roller. By means of the grooves on the shaft rolling surface, the rolling friction or at the beginning of the static friction between the roller and the drive shaft can be increased, so that the Rolling friction is greater than the sliding friction between the roller and the roller shoe and thus the roller is placed in a sufficient rotational movement to prevent slippage.

In an additional embodiment, the direction of the, in particular rectilinear, grooves is oriented substantially perpendicular to the running direction to form a micro-toothing between the shaft rolling surface and the roller rolling surface. A substantially perpendicular orientation of the direction of the grooves to the running direction means that the grooves are aligned with a deviation of less than 30 °, 20 °, 10 ° or 5 ° perpendicular to the running direction. The grooves are thus aligned substantially parallel to a rotational axis of the drive shaft or to a rotational axis of the roller. As a result, a micro-toothing forms between the roller and the shaft rolling surface of the drive shaft, so that thereby the rolling friction between the roller and the drive shaft can be increased. In particular, during a starting operation of the high-pressure pump so that a slip between the drive shaft and the roller can be substantially avoided.

In a complementary variant, the grooves are formed on the entire shaft rolling surface and the entire roller rolling surface.

The high-pressure pump preferably has two or three pistons and cylinders and / or the at least one roller is each slidingly mounted in a roller shoe.

In particular, the plain bearing by means of fuel, for. As gasoline or diesel lubricated.

In a further embodiment, a contact surface between the roller rolling surface and the shaft rolling surface is lubricated by means of fuel.

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.

A motor vehicle according to the invention comprises one in this

Patent application described high-pressure pump and / or a high-pressure injection system described in this patent application and / or an internal combustion engine 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 shows:

Fig. 1 shows a cross section of a high-pressure pump in a first

embodiment

2 shows a cross section of the high-pressure pump in a second

Embodiment,

3 a section AA according to FIG. 1 of a roller with roller shoe and a drive shaft, FIG. 4 is a development in plan view of a shaft rolling surface of the drive shaft of the high pressure pump of FIG. 1,

5 shows the development in plan view of the shaft rolling surface of the drive shaft of the high-pressure pump according to FIG. 2, FIG.

6 shows the development in plan view of a roller rolling surface of a roller of the high-pressure pump according to FIG. 2, FIG.

Fig. 7 is a highly schematic view of a high-pressure injection system and

Fig. 8 is a view of a motor vehicle.

Embodiments of the invention

In Fig. 1 and 2 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.

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 2 and is perpendicular to the plane of Fig. 3. A piston 5 is in a cylinder 6 with a

Supported piston guide 7, 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 chamber 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 to the effect that only fuel can flow into the working space 29 and the exhaust valve 20, z. B. a check valve, is designed such 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 in the roller shoe 9, a rotational movement whose axis of rotation 25 in the plane of FIG. 1 and 2 and is perpendicular to the plane of Fig. 3. 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. The roller 10 is located at a

Contact surface 12 on the shaft rolling surface 4 on.

In the second embodiment shown in FIG. 2, a plain bearing 13 and a sliding bearing 13 of the roller 10 in the roller shoe 9 is designed differently than in the first embodiment shown in FIG. 1 and 3. The plain bearing 13 is shown in Fig. 3 for the first embodiment shown in FIG 1. It is in the

Section according to FIG. 3, the roller 10 to more than 50% in contact with the sliding bearing 13, which is formed by the roller shoe 9. The sliding bearing 13 is lubricated by means of fuel. Differently the embodiment of the sliding bearing 13 for the second embodiment of the high-pressure pump 1 (not shown). Here, no slide bearing 13 is formed in the region of the roller rolling surface 1 1, but at the end of the roller 10 is rotationally symmetrical to the

Rotation axis 25 of the roller 10, a bearing pin is formed, which is mounted by means of a bearing bush in the roller shoe 9 (not shown). 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 from. The roller shoe 9 is mounted in a roller shoe bearing formed by the housing 8 as a sliding bearing. A spring 27 or coil spring 27 as an elastic element 28 which is clamped between the housing 8 and the roller shoe 9, brings on the roller shoe 9 a compressive force, so that the roller rolling surface 1 1 of the roller 10 in constant contact with the waves 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 the first embodiment of the high-pressure pump 1 according to FIGS. 1, 3 and 4, the shaft rolling surface 4 of the drive shaft 2 partially with grooves 40 as a Roll area 41 provided. The drive shaft 2 has two cams 3, so that two top dead centers 14 and two bottom dead centers 15 result on the drive shaft 2 (FIG. 3). This results in the wave rolling surface 4 two

Cam runs 17 and two cam ramps 18. At the two

Nockenabläufen 17 moves the roller 10 and the piston 5 according to the

Representation in Fig. 1 from top to bottom and at the cam ramp 18, the roller 10 and the piston 5 moves as shown in Fig. 1 upwards at a corresponding contact according to the

Rotary position of the drive shaft 2 with the cam outlet 17 and the cam ramp 18 and the roller 10. In the direction of a running direction 16 are on the shaft rolling surface 4 before bottom dead center 15 on the cam outlet 17 each with grooves 40 formed as groove portions 41 (Fig 1, 3 and 4). Between the drive shaft 2 and the roller 10, a rolling contact is present on a contact surface 12 and on the sliding bearing 13 between the roller 10 and the roller shoe 9 is a sliding contact. At a standstill of the high-pressure pump 1, the drive shaft 2 initially performs no rotational movement about the axis of rotation 26. During a starting operation of the high pressure pump 1, the drive shaft 2 is set in a rotational movement about the axis of rotation 26 and also the roller 10 in a rotational movement about the

Rotation axis 25 offset if the friction on the rolling contact is greater than the friction on the sliding contact. In particular, when starting from a complete rotational standstill, this condition can not be met, because a hydrodynamic lubricant film between sliding and rolling contact is displaced at a standstill and the frictional forces thereby reach a maximum. At standstill occur in the rolling contact two oppositely curved surfaces and

Sliding contact two corrugated surfaces in contact with each other. As a result, the contact surface is greater in sliding contact than in the rolling contact and thus touch more surface tips, which is the adhesive

Friction coefficient increased. This coefficient of friction is also increased when it comes to bonding due to fuel deposits. Due to the larger surface differences, this also has a stronger effect in sliding contact than in rolling contact. This complicates the rotation of the roller 10 from a standstill, as soon as the drive shaft 2 is set in a rotational movement. By the

Standstill of the roller 10, the balance of power is further deteriorated, as a hydrodynamic lubricating wedge between the shaft rolling surface 4 and the roller rolling surface 1 1 builds up, whereby the coefficient of friction in the rolling contact and thus the friction on the rolling contact is reduced. As a result, there is a slip between the shaft rolling surface 4 and the roller rolling surface 1 1, which can lead to wear damage. Because of the training of the two

Groove portions 41 on the shaft rolling surface 4, the friction on the

Rolling contact between the drive shaft 2 and the roller 10 are increased, and thus the above-mentioned condition are met, so that the friction on the rolling contact is greater than the friction on the sliding contact. The grooves 40 on the shaft rolling surface 4 increase the adhesive friction coefficient at the shaft rolling surface 4.

Rolling surface 4 and the rolling contact and also cause the Wälzkontakt a lesser lubricating film is present. As a result, a higher coefficient of friction occurs at the rolling contact and a higher frictional force thus occurs at the rolling contact. As a result, slippage between the roller 10 and the drive shaft 2 can be substantially avoided, in particular even during a starting operation of the high-pressure pump 1.

The depth of the grooves 40 in the first embodiment of the high pressure pump 1 is in the range of about 2 to 4 μιη. At the wave rolling surface 4, crack initiation in the area of the surface or even pitting may occur. Due to the formation of the two groove portions 41 on the

Cam outlet 17 shortly before bottom dead center 15, the groove portions 41 are used at the areas of the shaft rolling surface 4, in which the lowest pressure forces between the roller 10 and the drive shaft 2 occur. As a result, such damage to the shaft rolling surface 4 can be avoided altogether because the groove regions 41 which are particularly susceptible to these damages are used in areas with the lowest compressive force and, on the other hand, in particular during a starting operation, after a single sufficient rotational movement of the roller 10 due to the two Groove areas 41, substantially no more slip occurs. For a tearing of the roller 10, d. H. a displacement of the roller 10 in a rotational movement at a

Standstill of the roller 10, it is essentially irrelevant to which portion in the direction of the running direction 16, a groove portion 41 is formed. To avoid damage, for example, a pitting, therefore, the groove portions 41 are in the range of the least-acting pressure forces on the

Shaft rolling surface 4 is arranged. 2, 5 and 6, a second embodiment of the high pressure pump 1 is shown. In the following, only the differences from the first exemplary embodiment of the high-pressure pump 1 with the grooves 40 or groove regions 41 will be described essentially. The entire shaft rolling surface 4 and the entire roller rolling surface 1 1 is provided with grooves 40 and a groove portion 41. The grooves 40 and Bearbeitungsriefen 40 are each perpendicular to the running direction 16 of the drive shaft 2 and the roller 10. The grooves 40 and Bearbeitungsriefen 40 are thus substantially parallel to the axis of rotation 25 of the roller 10 and the axis of rotation 26 of the drive shaft

2 aligned. The grooves 40 as a micro-toothing 42 increase the friction on the rolling contact between the drive shaft 2 and the roller 10, thereby the friction due to a Mikroverzahnungseffekt.es

Rolling contact is increased. As a result, a slip between the drive shaft 2 and the roller 10, in particular during a starting operation of the high-pressure pump

1, be avoided. The orientation of the grooves 40 perpendicular to the

Running direction 16 or parallel to the axis of rotation 25 of the roller 10 further causes the hydrodynamic bearing capacity is increased to the sliding bearing 13 and thereby the friction is reduced to the sliding contact. Also, the slide bearing 13 on the roller shoe 9 may optionally be formed with the grooves 40 with an orientation perpendicular to the running direction 16 (not shown).

In Fig. 7 is a highly schematic representation of the high-pressure injection system 36 for a motor vehicle 38 shown 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).

The details of the various embodiments may be combined with each other unless otherwise specified.

Overall, considerable advantages are associated with the high-pressure pump 1 according to the invention and the high-pressure injection system 36 according to the invention. Due to the increased rolling friction between the roller 10 and the drive shaft 2 occurs between the roller 10 and the drive shaft 2 in

Essentially no play or slippage on, so the burdens of the

Roller shoe 9 are low. In particular, between the roller 10 and the drive shaft 2 thus occurs on the shaft rolling surface 4 and the roller rolling surface 1 1, a much lower wear, because the slip between the rolling surfaces 4, 1 1 is substantially excluded.

Claims

Expectations

High-pressure pump (1), in particular for a motor vehicle (38), 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),

- whereby the at least one piston (5) moves indirectly by means of

at least one roller (10) with a roller rolling surface (1 1) on a shaft rolling surface (4) of the drive shaft

(2) with 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 shaft rolling surface (4) and / or the roller rolling surface (1 1) with grooves (40) to increase the roughness of the shaft roller surface (4) and / or the roller rolling surface (1 1) are provided.

High-pressure pump according to claim 1, characterized in that the grooves (40) are straight or curved. High-pressure pump according to claim 1 or 2, characterized in that the shaft rolling surface (4) and / or the roller rolling surface (1 1) at least partly, in particular completely, made of steel

and or

the shaft rolling surface (4) and/or the roller rolling surface (1 1) is only partially provided with grooves (40), in particular in the direction of a running direction (16), so that the roughness of the shaft rolling surface (4) and / or the roller rolling surface (1 1) outside the grooves (40) is smaller than on the grooves (40).

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

Claims, characterized in that the grooves (40) have a depth in the range between 1 and 20 μm, in particular between 2 and 10 μm.

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

Claims, characterized in that the, in particular straight, grooves (40) are essentially aligned in the direction of the running direction (16).

6. High-pressure pump according to claim 5, characterized in that the grooves (40) are formed only on the shaft rolling surface (4).

7. High-pressure pump according to claim 6, characterized in that the grooves (40) on the shaft running surface (4) are formed only on at least one section in the running direction (16).

8. High-pressure pump according to claim 7, characterized in that the grooves (40) on the at least one section in the running direction (16) before a bottom dead center (15) on a cam sequence (17) of the drive shaft (2) with the at least one cam ( 3) are trained.

9. High-pressure pump according to one or more of claims 1 to 4, characterized in that the direction of the, in particular straight, grooves (40) are aligned essentially perpendicular to the running direction (16) to form a micro-toothing (42) between the shaft Rolling surface (4) and the roller

Rolling surface (1 1).

10. High-pressure pump according to claim 9, characterized in that the grooves (40) are formed on the entire shaft rolling surface (4) and the entire roller rolling surface (1 1).

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

Claims, characterized in that the high-pressure pump (1) has two or three pistons (5) and cylinders (6).

and or

the at least one roller (10) each in a roller shoe (9)

is plainly mounted.

12. High-pressure injection system (36) for an internal combustion engine (39), in particular for a motor vehicle (38), 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.

13. High-pressure injection system according to claim 12, characterized in that the high-pressure injection system (36) has a metering unit (37) which controls or regulates the amount of fuel delivered from the pre-feed pump (35) to the high-pressure pump (1) per unit of time.

14. Internal combustion engine (39) with a high-pressure injection system (36), in particular for a motor vehicle (38), characterized in that the high-pressure injection system (36) is designed according to claim 12 or 13 and / or the internal combustion engine (39).

High-pressure pump (1) according to one or more of claims 1 to 1 1.