DE10313745A1 - High pressure pump for IC engine fuel injection device e.g. for automobile, with hydrodynamic lubrication of bearings for ring segments operating pistons of pump elements - Google Patents

Abstract

The high pressure pump has a housing enclosing a rotary drive shaft having a shaft section (16) eccentric to its rotation axis, provided with a sliding ring (18). The housing is fitted with a number of pump elements (14), each having a piston (20) driven by the ring, which is divided into corresponding ring segments, spaced from one another by intermediate gaps (40) allowing hydrodynamic lubrication of the ring segment bearings.

Description

State of technology

The invention is based on one High pressure pump for a fuel injection device of an internal combustion engine the type of claim 1.

Such a high pressure pump is through the DE 198 29 548 A1 known. This high-pressure pump has a housing in which a drive shaft is rotatably mounted. The drive shaft has a shaft section which is formed eccentrically to its axis of rotation and on which a ring is slidably mounted. A plurality of pump elements are arranged in the housing, each of which has a pump piston which is driven at least indirectly by the ring in a stroke movement. The pump pistons can be supported by tappets on the ring. The ring is divided into several ring segments over the circumference of the drive shaft, with one ring segment being assigned to each pump piston. The ring segments can adapt freely in the circumferential direction to the respective pump piston or to the plunger arranged between the respective pump piston and the ring segment, by means of which the pump piston is supported on the ring segment, and thereby enable the ring segments and the pump piston or the plunger to be subject to little wear Area of the system between ring segments and pump pistons or tappets. However, it is disadvantageous that the ring segments are arranged at a large distance from one another in the circumferential direction, as a result of which the lubrication of the bearing of the ring segments on the shaft section is impaired and thus increased wear of the shaft section and / or the ring segments can occur.

The high pressure pump according to the invention with the features according to claim 1 has in contrast the advantage that the wear of the Storage of the ring segments on the shaft section kept low can be.

In the dependent claims are advantageous refinements and developments of the high-pressure pump according to the invention specified. The training according to claim 2 enables hydrodynamic lubrication of the bearing in a simple manner. The training according to claim 3 enables another improvement in hydrodynamic lubrication. Training according to claim 4 enables a reduction in weight of the ring segments and thus relief of storage. The training according to claims 4 and 5 allows a connection of the ring segments while maintaining movement of the ring segments in the circumferential direction to each other. The training according to claims 7 and 8 allows a cohesion of the ring segments on the shaft section. The Continuing education according to claim 9 allows a change the angular position of the ring segments also with respect to a radial plane of the Wave section and thus a further improved adaptation of the Alignment of the ring segments at least indirectly with the pump pistons.

drawing

Several embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it 1 a high-pressure pump in a cross-section, 2 the high pressure pump in a cross section along line II-II in 1 according to a first embodiment, 3 the high pressure pump in sections in cross section according to a modified version, 4 the high pressure pump in sections in cross section according to a second embodiment, 5 the high-pressure pump in sections in a longitudinal section according to a third embodiment, 6 the high pressure pump in sections in a longitudinal section according to a fourth embodiment and 7 the high pressure pump according to one opposite 6 modified version.

In the 1 to 7 A high-pressure pump for a fuel injection device of an internal combustion engine, for example of a motor vehicle, is shown. The high-pressure pump delivers fuel under high pressure of up to over 2000 bar, for example into a storage tank 8th , from which fuel is taken for injection on the internal combustion engine. The high-pressure pump is designed as a radial piston pump and has a housing 10 on where a drive shaft 12 around an axis 13 is rotatably mounted. In the housing 10 are several, for example three pump elements 14 arranged by the drive shaft 12 are driven. The drive shaft 12 has an eccentric to its axis of rotation 13 trained shaft section 16 on which several ring segments 18 are rotatably mounted. The pump elements 14 each have a pump piston 20 on that in an at least approximately radial to the axis of rotation 13 the drive shaft 12 running cylinder bore 22 is slidably guided. The pump piston 20 each pump element 14 is supported by a pestle 24 on one ring segment each 18 from. The pestle 24 is in a hole 26 in the housing 10 at least approximately coaxial to the pump piston 20 slidably guided. The pump piston 20 will with his piston base 21 by a spring 28 on the one hand on the housing 10 and on the other hand via a spring plate 23 on the piston foot 21 supports, in contact with the ram 24 held and the pestle 24 is by the spring 28 in contact with the ring segment 18 held. Every ring segment 18 has a flat on its outside 19 on which the respective plunger 24 is applied. The flattening 19 has an at least approximately flat surface and the plunger 24 shows the flattening 19 facing an at least approximately flat contact surface.

Through the respective pump piston 20 becomes a pump work room 30 limited by one in the pump work room 30 opening inlet valve 32 can be connected to a fuel supply in which there is low pressure. The pump work room 30 is also through an outlet valve opening to the accumulator 34 with the store 8th connectable. When the drive shaft rotates 12 becomes the pump piston 20 over the eccentric shaft section 16 the drive shaft 12 and the respective ring segment 18 driven in one stroke. If the pump piston 20 moves radially inward, this performs a suction stroke, the inlet valve 32 is open so that fuel is in the pump work space 30 flows in while the exhaust valve 34 closed is. If the pump piston 20 moves radially outward, this carries out a delivery stroke, the inlet valve 32 is closed and that of the pump piston 20 compressed fuel through the open exhaust valve 34 under high pressure in the store 8th arrives.

In 2 the high pressure pump is shown according to a first embodiment. Between the ring segments 18 is in the circumferential direction of the shaft section 16 , on which they are arranged, one gap each 40 available. The width of this gap 40 is so large on the one hand that the ring segments 18 independently of each other to the plungers 24 can align such that a flat contact of each plunger 24 on the flattening 19 of the ring segment assigned to it 18 is ensured. On the other hand is the gap 40 chosen so low that in the bearing of the ring segments 18 on the wave section 16 hydrodynamic lubrication is ensured. The ring segments 18 can directly on the shaft section 16 be stored or via a between the ring segments 18 and the shaft section 16 arranged bearing shell. It can also be provided that the shaft section 16 and / or the ring segments 18 are provided on their contact surfaces with a coating of a material with favorable sliding properties. When the drive shaft rotates 12 the pump pistons move 20 through the eccentric shaft section 16 causes alternately in the radial direction outwards and inwards, whereby the ring segments 18 not with the drive shaft 12 rotate with it, but through the supporting plungers 24 be held. The ring segments 18 are all identical and can preferably be made from an extruded profile.

The ring segments 18 can, as in 2 shown in the area of the flats 19 a larger extension in the radial direction with respect to the central axis 17 of the shaft section 16 have as in their areas facing the adjacent ring segments. For the ring segments 18 then result as in 2 shown between the flats 19 compared to a full ring cross section, for example, concave depressions. As a result, the mass of the ring segments 18 reduced, thereby reducing the weight of the high-pressure pump and the load on the bearing. In addition, there is greater security against the ring segments jumping off 18 from the wave section 16 and against the pump pistons jumping off 20 from the ring segments 18 reached.

In 3 the high pressure pump is shown according to a modified embodiment compared to the first embodiment. The basic structure of the high pressure pump is the same as in the first embodiment, with the ring segments 118 are designed here such that they partially overlap in the circumferential direction, but a movement of the ring segments 118 is made possible independently of one another in the circumferential direction. Every ring segment 118 overlaps an adjacent ring segment on one side 118 with a reduced outer jacket section 118a , with the adjacent ring segment 118 in the overlapping area also a reduced inner jacket section 118 having. The circumferential direction between the ring segments 118 existing gap 40 does not run radially from the shaft section 16 outwards between the ring segments 118 but due to the overlapping jacket sections 118a . 118b like a labyrinth. As a result, the hydrodynamic lubrication of the ring segments 118 on the wave section 16 improved because fuel passes from the shaft section 16 outwards between the ring segments 118 through is difficult. The ring segments 118 are preferably all identical in this embodiment and can be made from an extruded profile.

In 4 the high pressure pump is shown according to a second embodiment, in which the basic structure is again the same as in the first embodiment. The ring segments 218 partially overlap in the circumferential direction as in the embodiment according to 3 , but are additionally hooked into each other. Every ring segment 218 points to the adjacent ring segment 218 facing peripheral side an L-shaped hook 218a . 218b on. On a peripheral side of the ring segment 218 points the hook 218a with its free end pointing radially inwards and on the other circumferential side hook 218b with its free end radially outwards. Every ring segment 218 overflowing with his hook 218a the hook 218b of this adjacent ring segment 218 , being in the circumferential direction by the between the ring segments 218 existing gap 40 a movement of the ring segments 218 is possible independently. The ring segments 218 are all identical and can be made from an extruded profile.

In 5 the high pressure pump is shown according to a third embodiment, in which the basic structure is again the same as in the first embodiment. The ring segments 318 can as in the 2 to 4 be formed and are formed by at least one annular holding element spanning these 350 on the wave section 16 held together. The ring segments 318 point at least one in the direction of the central axis 17 of the shaft section 16 facing side a head start 352 on that with a smaller radial distance from the shaft section 16 is arranged as the flattening 19 of the respective ring segment 318 , The tabs 352 of the ring segments 318 form at on the shaft section 16 arranged ring segments 318 at least approximately a circular cross-section, which the ring-shaped holding element 350 spans. The holder ring 350 can in cross section as in 5 shown rectangular on the left or as in 5 shown round on the right in cross section. The tabs 352 can like in 5 a groove-like depression is shown on the right 353 have in the holding element 350 arranged and thus against slipping on the ring segments 318 be secured. The ring segments preferably have 318 as in 5 shown a projection on both sides 352 on and it's on both sides of the ring segments 318 one each the ledges 352 spanning holding element 350 arranged. The holding element 350 is preferably designed as a resilient ring and holds the ring segments 318 on the wave section 16 under tension together. The ring segments 318 can in spite of the holding element 350 move independently of each other in the circumferential direction due to the gaps between them.

In 6 the high pressure pump is shown according to a fourth embodiment, in which the basic structure with the separate ring segments 418 is the same as in one of the above-described versions of the high pressure pump. In the fourth embodiment, the outside of the shaft section 416 in its central axis 417 containing longitudinal sections outwardly convexly curved, the curvature being at least approximately formed by a radius R. The corresponding is at the shaft section 416 adjacent inside of the ring segments 418 in the central axis 417 of the shaft section 416 containing longitudinal sections concavely curved with at least approximately the same radius of curvature as the shaft section 416 , Through this design of the shaft section 416 and the ring segments 418 can the ring segments 418 not only align freely in the circumferential direction independently of one another but also in their angular position with respect to a radial plane 454 to the shaft section 416 , In this way, also in longitudinal section as in 6 shown a flat system of the plunger 24 on the flats 419 of the ring segments 418 ensured even if the contact surfaces of the plunger 24 and / or the flattenings 419 of the ring segments 418 due to manufacturing tolerances not exactly perpendicular to the radial plane 454 of the shaft section 416 lie. The ring segments 418 can adjust themselves independently of each other in their angular position so that the plungers rest flat 24 results in a further reduced wear of the plunger 24 and the ring segments 418 is achieved.

In the embodiments of the high-pressure pump explained above, the tappets can 24 also omitted, whereby then as in 7 shown the pump pistons 420 directly with their piston feet 421 on the flats 419 of the ring segments 418 support. The holes 26 in the housing 10 to guide the plunger 24 can also be omitted, which simplifies the manufacture of the high pressure pump. In particular, the design of the high pressure pump according to the fourth embodiment with the pivotable mounting of the ring segments 418 on the wave section 416 enables alignment of the ring segments 418 to the piston feet 421 such that the piston feet 21 flat on the flats 419 of the ring segments 418 and there is little wear.

Claims (10)

High-pressure pump for a fuel injection device of an internal combustion engine, with a housing ( 10 ), with one in the housing ( 10 ) rotatably mounted drive shaft ( 12 ) that are eccentric to their axis of rotation ( 13 ) trained shaft section ( 16 ; 416 ) on which a ring ( 18 ; 118 ; 218 ; 318 ; 418 ) is slidingly mounted, with several in the housing ( 10 ) arranged pump elements ( 14 ), each with a pump piston ( 20 ; 420 ) through the ring ( 18 ; 118 ; 218 ; 318 ; 418 ) is driven at least indirectly in one stroke, the ring extending over the circumference of the shaft section ( 16 ; 416 ) in several ring segments ( 18 ; 118 ; 218 ; 318 ; 418 ) is divided and each pump piston ( 20 ; 420 ) a ring segment ( 18 ; 118 ; 218 ; 318 ; 418 ), characterized in that the circumferential direction between the ring segments ( 18 ; 118 ; 218 ; 318 ; 418 ) existing column ( 40 ) like this are designed such that hydrodynamic lubrication of the bearing of the ring segments ( 18 ; 118 ; 218 ; 318 ; 418 ) on the shaft section ( 16 ; 416 ) is possible. High-pressure pump according to claim 1, characterized in that the ring segments ( 118 ; 218 ) partially overlap in the circumferential direction. High-pressure pump according to claim 2, characterized in that between the ring segments ( 118 ; 218 ) labyrinthine gaps are formed. High-pressure pump according to one of claims 1 to 3, characterized in that the radial extension of the ring segments ( 18 ) in areas where this is less than in areas ( 19 ) in which the pump pistons ( 20 ; 420 ) at least indirectly on the ring segments ( 18 ) support. High-pressure pump according to one of claims 1 to 4, characterized in that the ring segments ( 218 ) are interlocked in such a way that movement of the ring segments ( 218 ) is made possible independently of one another in the circumferential direction. High-pressure pump according to claim 5, characterized in that each ring segment ( 218 ) an L-shaped hook on each of its two peripheral sides ( 218a . 218b ) and with a hook ( 218a ) a hook ( 218b ) of an adjacent ring segment ( 218 ) overlaps. High-pressure pump according to one of the preceding claims, characterized in that the ring segments ( 318 ) by means of at least one holding element spanning these ( 350 ) on the eccentric shaft section ( 16 ) are held. High-pressure pump according to claim 7, characterized in that the at least one holding element ( 350 ) is designed as a resilient ring. High-pressure pump according to one of the preceding claims, characterized in that the outside of the eccentric shaft section ( 416 ) in its central axis ( 417 ) containing longitudinal sections is convex and that the inner sides of the ring segments ( 418 ) with which these are on the outside of the shaft section ( 416 ) are concave. High-pressure pump according to one of the preceding claims, characterized in that the pump pistons ( 420 ) directly with their piston feet ( 21 ) on the ring segments ( 418 ) support.