WO2012048961A1

WO2012048961A1 - High-pressure pump for a fuel injection device

Info

Publication number: WO2012048961A1
Application number: PCT/EP2011/065472
Authority: WO
Inventors: Alfons Schoetz; Markus Schetter
Original assignee: Robert Bosch Gmbh
Priority date: 2010-10-15
Filing date: 2011-09-07
Publication date: 2012-04-19
Also published as: CN103154512B; DE102010042484A1; EP2627903A1; EP2627903B1; CN103154512A

Abstract

The invention relates to a high-pressure pump (1) of a fuel injection device, which can be used in particular for a common rail injection device of an internal combustion engine. The high-pressure pump (1) comprises a pump shaft or drive shaft, which is connected to an eccentric (6) in a rotationally rigid manner, and at least one pump element (8). The pump element (8), including a bucket tappet (13), a piston element (12) and a tappet spring (14), is inserted into a housing bore (16) of an engine block (3). The bucket tappet (13), on which the tappet spring (14) acts, is connected to the piston element (12), which is guided such that it can be moved in a reciprocating manner in a cylinder bore (19) of a shaft section (20) and which delimits a pump working chamber (21) connected to a suction valve (22) and a high-pressure valve (23). A drive connection between the bucket tappet (13) and the eccentric (6) comprises a running ring (9) rotatably mounted on the eccentric (6), on which the sliding plate (18) of the bucket tappet (13) is supported in a force-closed manner.

Description

description

title

High pressure pump for a Kraftstoffeinspritzvorununq

The present invention relates to a high pressure pump of a fuel injection device, which can be used in particular for a common rail injection device of an internal combustion engine. The high-pressure pump comprises a pump or drive shaft, which is rotationally rigidly connected to an eccentric and is in operative connection with a pump element. The one bucket tappet, an element piston and a plunger spring enclosing pump element is associated with a housing bore of an engine block. The element piston, which is drive-connected to the eccentric via the cup tappet and can be moved in a cylinder bore, delimits a pump working chamber connected to a suction valve and a high-pressure valve.

State of the art

Such high-pressure pumps are used in motor vehicle construction in order to achieve a necessary volume flow and required fluid pressure for a common-rail system.

Fuel system to provide. The high-pressure pump is subject to heavy loads, in particular mechanical stresses, so that high demands are placed on the material and on the construction. The bucket tappet operatively connected to an eccentric or a cam track effects a conversion from the rotational movement of the drive shaft into an oscillating stroke movement of an element or pump piston. The lifting movement of the element piston can be divided into a suction and compression stroke. During the suction stroke, fuel is sucked into a pump working space via a suction valve. In the subsequent compression stroke, the fuel is compressed and conveyed via an open high-pressure valve in a memory (rail). Due to the self-adjusting friction between the element piston and a cylinder bore and a tappet guide a restoring force performing pestle spring is used, which establishes a non-positive contact between the tappet and the eccentric. DE 101 57 076 A1 discloses a plunger piston for a high-pressure pump with a plunger, which includes an axially and radially guided roller and a piston fixedly connected to the plunger. To guide the roller on the plunger it is provided with a roller shoe in which the roller is rotatable and inserted with an axial play.

From DE 199 07 31 1 A1 discloses a high-pressure pump is known, which has a drive shaft with eccentric, which cooperates with a pump element. Between the element piston and the eccentric, a support element or a roller shoe is arranged, in which a rotatably mounted, rolling on the eccentric roller is inserted. In this structure, there is a risk that a relatively large amount of wear due to increased friction between the directly operatively connected components arises. The increased friction affects the rotational movement of the roller, whereby slippage between the roller and the eccentric can occur and the wear increases.

The object of the invention is to provide a high-pressure pump with a simplified, robust and friction-optimized drive connection between the eccentric and the bucket tappet, which withstands high mechanical loads and is easy to produce.

DISCLOSURE OF THE INVENTION This object is achieved in that a drive connection between the bucket tappet and the eccentric comprises a rotatably mounted on the eccentric race on which the bucket tappet is non-positively supported. The tappet is thus drivingly connected via the rotatably mounted race indirectly to the eccentric.

The inventive, the eccentric enclosing and a relative movement to the eccentric exercising race advantageously causes a decoupled drive connection or power transmission between the tappet and the eccentric. This arrangement reduces the transverse force absorption of the bucket tappet and consequently advantageously reduced lateral or transverse forces can be realized by the bucket tappet in its guide on the housing bore. The inventive concept provides a simplified and robust drive connection between the eccentric and bucket tappets, the advantageous heavy loads, in particular mechanical stresses withstand, which has a positive effect on the life. The friction-optimized drive connection is also independent of friction conditions, which were to be considered in previous solutions between a bucket tappet and eccentric, for example between a roller and an eccentric. In addition, the inventive robust drive connection is insensitive to different

Fuel viscosities.

A further advantage of the invention is that the drive connection according to the invention can be transferred both to high-pressure pumps with a 1-fold cam system or eccentric system and to high-pressure pumps with a 2-fold cam system. In comparison to known solutions, in which the tappet is supported on the eccentric via a roll integrated in the roller shoe, the friction connection according to the invention advantageously results in reduced friction. By the invention can advantageously be realized a permanent drive connection between the eccentric and the bucket tappet, which can also be used for highly dynamic systems with correspondingly high pump pressures and pump speeds.

At the same time, the concept according to the invention, which can be implemented easily, ensures reliable, precise operation, combined with low wear, which results in an overall increase in efficiency.

A preferred embodiment of the invention provides that the bucket tappet on the drive side is associated with a designated also as a force receiving device sliding plate. The preferably pressed into the cup tappet and fixed in position sliding plate is supported with a contact surface on the associated contact surface of the eccentric enclosing race, wherein the contact surfaces together form a contact zone. Advantageously, the sliding plate is made of a material adapted to the given loads and lubricant conditions. To achieve a high wear resistance, it makes sense, for example, to produce the sliding plate made of hard metal or a ceramic material. The tappet with integrated sliding plate is further characterized by a simplified and component-optimized

Construction. Due to the sliding plate, the tappet advantageously requires neither a position-oriented mounting position nor an anti-twist device, which simplifies assembly. The inventive simplified and cost-optimized bucket tappet concept also offers a cost advantage over known solutions of tappets with roller shoe and integrated role.

To minimize friction, the race is rotatably mounted on the eccentric shaft via a rolling bearing or sliding bearing. By the use of commercial Wälz- or Plain bearings can be a robust, proven and inexpensive storage of the race on the eccentric shaft can be realized. As roller bearings are preferably cylindrical roller bearings, since the storage has to absorb any axial forces. Due to the small radial space required, it is preferable to use needle bearings for the bearing of the race.

Another particular embodiment of the invention is characterized in that at least one of the mutually facing contact surfaces of the sliding plate and the race is slightly convex or convex. This measure advantageously compensates for slight angular errors that can occur during production due to permissible position and / or shape tolerances. The convexity also serves to reduce the contact area between the slide plate and the raceway to line contact, thereby advantageously reducing friction. To achieve an increased service life of the drive connection, it is provided according to the invention to coat at least one contact surface of the race or the sliding plate with a material of high wear resistance. Alternatively or additionally, the invention further includes a coating of at least one contact surface with a friction-reducing material.

According to a further advantageous embodiment, the high pressure pump designed as a plug-in pump is used as a structural unit with a plug-in pump body in a housing bore of the engine block. In a shaft portion of the plug-in pump body, a cylinder bore is introduced, which is intended to guide the element piston and at the same time forms the pump working space. Advantageously, the offers

Invention, the possibility of creating a high-pressure pump in which the principle of a plug-in pump is combined with a drive connection having a mounted on the eccentric shaft raceway and a bucket tappets with integrated sliding plate.

The structural design of the invention further includes different solutions for guiding the bucket tappet. An outer guide of the tappet is preferred, in which a tappet body of the tappet is guided over a lateral surface in the housing bore of the engine block. This outer guide of the tappet prevents deformation of the guide of the element piston in the shaft portion.

Alternatively, it is advisable to guide the tappet inside the shaft portion of the plug-in pump body. In a further embodiment of the invention, a space-optimized arrangement of the plunger spring is also provided for the designed as a plug-pump high-pressure pump. For this purpose, the plunger spring is supported on an integrated inside the cup tappet spring plate, wherein the plunger spring is guided over a greater length within the plunger body. The mutual spring end of the plunger spring is enclosed for guiding by a board of the plug-in pump body.

For targeted and effective lubrication of the leadership of the tappet in the housing bore at least one preferably circumferential lubrication groove is introduced in a lateral surface of the tappet body, which are connected via associated passage bores with a plunger interior. This measure has the effect that a lubricant, in particular the fuel delivered by the high-pressure pump, enters the annular gap which is established between the housing bore of the engine block and the lateral surface of the cup tappet. As a result, an optimal, friction-reducing lubrication of the bucket tappet can be realized. Furthermore, the lubricant passes for cooling and lubrication in the defined by the race and the sliding plate contact zone of the drive connection between the eccentric and the bucket tappet. As a supplementary measure for the supply of lubricant to the contact zone, the sliding plate of the tappet includes at least one flood hole.

Further advantageous embodiments of the invention are described in the drawings, are described in more detail in the embodiments illustrated in the figures of the invention. Brief description of the drawings

Show it:

Figure 1 is a sectional view of a high-pressure pump with a drive connection according to the invention between eccentric and bucket tappets.

2 as a single part drawing of the bucket tappet according to FIG. 1.

In FIG. 1, a high-pressure pump 1 for a fuel injection device is one

Internal combustion engine is shown, which is preferably intended for a common rail injection system of a diesel internal combustion engine. By the high-pressure pump 1 fuel under high pressure in a not shown in Fig. 1 memory (rail) is promoted. dert, from which the fuel is injected via fuel injectors targeted in associated combustion chambers of an internal combustion engine. The high-pressure pump 1 forms a radial piston pump, which is used as a plug-in pump with a plug-in pump body 2 in an engine block 3 or housing. The plug-in pump body 2 is adjoined by a low-pressure unit 4, which may also be referred to as a cylinder head. One in the engine block

3 rotatable drive shaft with an axis 5 is connected to an eccentric 6, whose central axis 7 has an eccentricity S with respect to the axis 5. The drive shaft may be a shaft of the internal combustion engine, for example, the camshaft or a balancer shaft.

The eccentric 6 is surrounded by a race 9, which is rotatably mounted on the eccentric 6 via a roller bearing 10, in particular a needle bearing with cylindrical rolling elements 1 1 and which is drivingly connected to a tappet 13 of a pump element 8. The pump element 8 comprises the bucket tappet 13, in which an element piston 12 or pump piston is held, as well as a tappet spring 14. About a

Plunger body 15, the cup tappet 13 is guided without rotation in a radially extending to the axis 5 of the drive shaft housing bore 16 of the engine block 3. The cup tappet 13 is supported on the raceway 9 of the eccentric member 6 via a sliding plate 18 inserted in a form-fitting manner in a receptacle 17 of the cup tappet 5 and fixed in position. In the operating state causes the rotating eccentric 6 in conjunction with the race 9, an oscillating movement of the tappet 13 and the associated element piston 12 which is guided in a cylinder bore 19 of a shaft portion 20 of the plug-in pump body 2. The element piston 8 defines a pump working space 21 to which a suction valve 22 and a high-pressure valve 23 are assigned. During a suction stroke (downward movement) of the element piston 8, the suction valve 22 opens, whereby the pump working chamber 21 fuel from the low pressure unit 4 can be supplied. A delivery stroke (upward movement) of the element piston 8 leads to the closure of the suction valve 22 and a fuel compression, before the fuel on the the function of a

Non-return valve exerting high-pressure valve 23 is conveyed in a further fuel line to a high-pressure accumulator (Rail). An eccentricity S between the axis 5 of the drive or pump shaft to the central axis 7 of the eccentric 6 simultaneously determines a maximum stroke of the element piston 12th

The one restoring force on the tappet 13 triggering plunger spring 14 is supported between the plug-in pump body 2 and a spring plate 24 of the tappet 13 and causes a frictional support of the tappet 13 on the Running ring 9. In this case, the plunger spring 14 surrounds the shaft portion 20 of the plug-in pump body 2, wherein a first spring end of the plunger spring 14 is enclosed by a board 25 of the plug-in pump body 2 and the further entering the tappet 13, supported on the spring plate 24 spring end on the outside of the plunger body 15 is enclosed.

To compensate for small angular errors, for example due to manufacturing tolerances of individual components, the eccentric 6 enclosing raceway 9 is supported via a convex, convex contact surface 27 on a correspondingly shaped counter surface, the contact surface 28 of the sliding plate 18 of the tappet 13. To achieve optimum friction conditions, a friction-reducing coating at least one contact surface 27, 28 is additionally suitable.

2 shows the tappet 13 as a single part in an enlarged view and illustrates further details. The used in the tappet 13, for supporting the plunger spring 14 certain spring plate 24 simultaneously causes a support of the element piston 12 on the tappet 13. For this, the element piston 12 is inserted in a central opening 26 of the spring plate 24 and through an opening 26 cross-end board 35 secured. Since the plunger body 15 are guided in the engine block 3 and the element piston 12 in the shaft portion 20 and thus in separate components, the element piston 12 is preferably performed with a small angular error compensating clearance in the opening 26 of the spring plate 24. As a measure to improve the friction of the plunger body 15 in the housing bore 16 of the engine block 3 is in a lateral surface 29 of the plunger body 15, a preferably circumferential lubrication 30 introduced circumferentially arranged through holes 31st In this way, a lubricant or the fuel delivered by the high-pressure pump 1 can selectively enter an annular gap 32 (FIG. 1) which is radially delimited by the plunger body 15 and the housing bore 16. From there comes the

Lubricant also in the direction of the eccentric 6 and applied for lubrication and cooling a contact zone 33 (Fig. 1) between the raceway 9 and the slide plate 18. In addition, a plurality of flood bores 34 are introduced in the slide plate 18, which allow a flow of lubricant to targeted to lubricate and cool the components of the contact zone 33.

Claims

claims

1 . High-pressure pump (1) of a fuel injection device, in particular for a common-rail injection device of an internal combustion engine, with a Pumpenwel- le with an eccentric (6) is rotationally rigidly connected and at least one in a housing bore (16) of an engine block (3) used Pump element (8) which includes a with the eccentric (6) via a bucket tappet (13) connected, hubbeweglich in a cylinder bore (19) of a shaft portion (20) guided element piston (12) and a tappet (13) acting on bump spring (14), wherein the element piston (12) bounded with a suction valve (22) and a high pressure valve (23) pump working space (21), characterized in that a drive connection between the tappet (13) and the eccentric (6) rotatable one on the eccentric (6) mounted raceway (9) on which the tappet (13) is non-positively supported.

2. High-pressure pump according to claim 1, characterized in that the tappet (13) on the drive side includes a sliding plate (18) as a contact surface (28) together with a contact surface (27) of the eccentric (6) enclosing race (9) has a contact zone (33) forms.

3. High-pressure pump according to claim 1, characterized in that the raceway (9) via a rolling bearing (10) or plain bearing on the eccentric (6) is rotatably mounted.

4. High-pressure pump according to claim 3, characterized in that as a rolling bearing (10) is provided a cylindrical roller bearing or needle bearing for supporting the race (9).

5. High-pressure pump according to claim 1 or 2, characterized in that the race (9) and / or the sliding plate (18) has a convex or convex contact surface (27,28).

6. High-pressure pump according to claim 1 or 2, characterized in that the contact surface (27) of the race (9) and / or the contact surface (28) of the sliding plate (18) is coated friction-reducing.

7. High-pressure pump according to claim 1, characterized in that the plug pump designed as a high pressure pump (1) with a plug pump body (2) in the housing bore (16) of the engine block (3) is used and for guiding the element piston (12) and forming a Pump working space (8) certain cylinder bore (19) in a shaft portion (20) of the plug-in pump body (2) is introduced.

8. High-pressure pump according to claim 1, characterized in that the tappet (13) on the outside via a plunger body (15) in the housing bore (16) of the engine block (3) or on the inside of the plug-in pump shaft (20) of the plug-in pump body (2) is guided.

9. High-pressure pump according to claim 1, characterized in that the plunger spring (14) is supported by a spring end on a spring plate (24) which is integrated in the cup tappet (13).

10. High-pressure pump according to claim 1, characterized in that for lubricant supply of a guide of the tappet (13) in the plunger body (15) at least one lubrication groove (30) is introduced, which via associated through-holes (31) having an interior of the tappet (13). connected is.

1 1. High-pressure pump according to claim 1 or 2, characterized in that for the lubricant supply to the contact zone (33) between the sliding plate (18) and the raceway (9) at least one flood bore (34) in the sliding plate (18) is introduced.