EP1060334B1 - Radial piston pump for fuel high pressure generation - Google Patents

Description

The invention relates to a radial piston pump for High-pressure fuel generation in fuel injection systems of internal combustion engines, especially in a common rail injection system, with one stored in a pump housing Drive shaft which is eccentric or in Has circumferential cam-like elevations, and with preferably several radially in relation to the drive shaft a piston arranged in each cylinder space, at the ends facing the drive shaft each have a plate is attached, which has a blind hole in the middle, in which is the end of the associated piston, wherein the piston has a groove on its circumference in which a snap ring is attached to a plate holder on the To attach the piston that holds the plate to the piston.

If the cylinder spaces are partially filled, Components of the radial piston pump under high pressure extremely heavily loaded.

The invention is therefore based on the problem of a Provide radial piston pump, which at a Partial filling of the cylinder pressures from to withstands up to 2000 bar and is still simple and inexpensive can be manufactured.

The problem is with a radial piston pump High-pressure fuel generation in fuel injection systems of internal combustion engines, especially in a common rail injection system, with one stored in a pump housing Drive shaft which is eccentric or in Has circumferential cam-like elevations, and with preferably several radially in relation to the drive shaft a piston arranged in each cylinder space, at the ends facing the drive shaft each have a plate is attached, which has a blind hole in the middle, in which is the end of the associated piston, wherein the piston has a groove on its circumference in which a snap ring is attached to a plate holder on the To attach the piston that holds the plate to the piston, solved in that at the edge of the blind hole in the plate a cylinder countersink is attached, the game between the snap ring and the circumference of the cylinder countersink is smaller than the depth of the groove. The cylinder countersink is used for mounting of the snap ring, more precisely, to accommodate the part of the Snap ring that protrudes from the groove. Through the Dimensioning of the cylinder counterbore according to the invention achieved that the snap ring tied up in its space becomes. As a result, greater forces can be transmitted than with conventional radial piston pumps.

This is a special embodiment of the invention characterized in that the radius of the groove is larger than that Radius of the snap ring. This dimensioning of the groove and the Snap rings provide the advantage that the snap ring is always in the Groove base lies and not on the edges of the groove. Thereby damage to the seat is avoided and the Snap ring preload can be optimally used. The Snap ring preload can be increased by the thickness and the diameter of the snap ring and the diameter of the groove increase.

Another special embodiment of the invention is characterized in that the area of Plate holder, which rests on the snap ring, radially to the Piston expands and is flat. This is the Snap ring more visible before the plate in the Plate holder is used. As a result, the Assembly is simplified and assembly errors Radial piston pump according to the invention can be avoided. Consequently can save valuable time and target zero errors can be better realized.

Another special embodiment of the invention is characterized in that a step on the plate holder is trained. The stage is used in an advantageous manner Centering a spring that is used to hold the plate to bias towards the drive shaft.

Another special embodiment of the invention is characterized in that the plate has a circumference Has groove in which a retaining ring is received, the abuts the plate holder. Due to the elastic Circlip becomes a non-positive and therefore free of play Connection between the plate holder and the plate reached. This ensures that the piston foot in the Operation remains in contact with the plate. When inserting the Plate in the plate holder gives way to the locking ring, see above that the plate holder can be rigid.

Another special embodiment of the invention is characterized in that on the plate holder Snap segments are formed on the circumference of the plate issue. The snap segments have compared to those from the Prior art known claws have the advantage that they are more stable due to their size. In addition, get caught the snap segments of a plate holder when storing not so easy with the snap segments of others Plate holder. This will assemble the plate holder simplified.

Another special embodiment of the invention is characterized in that the ends of the snap segments are each slightly bent outwards. This will make the Assembly of the plate simplified in an advantageous manner, because spread when inserting the plate into the plate holder the snap segments bent slightly outwards automatically.

Another special embodiment of the invention is characterized in that the ends of the snap segments each have a bevel. This will do the same Effect achieved as with the slightly curved outwards Snap segments. The assembly of the plate is simplified.

Another special embodiment of the invention is characterized in that between the drive shaft and the plate is a polygonal or cylindrical ring is arranged. The ring is used to transmit the forces from the eccentrically designed drive shaft on the plate. The ring is advantageously sliding on the drive shaft stored. The ring can either be cylindrical be formed or be flattened.

The present invention generally has the advantage that Basic idea of the present invention in a simple manner and Be applied to existing radial piston pumps can. In general, the component strength, especially at a zero funding in the suction stroke, increased without the installation space the radial piston pump increases.

Figur 1

zeigt einen Kolben und eine Platte von einer herkömmlichen Radialkolbenpumpe;

Figur 2

zeigt einen Kolben und eine Platte von einer Radialkolbenpumpe gemäß einer ersten Ausführungsform der vorliegenden Erfindung;

Figur 3

zeigt einen Kolben und eine Platte von einer Radialkolbenpumpe gemäß einer zweiten Ausführungsform der vorliegenden Erfindung;

Figur 4

zeigt einen Kolben und eine Platte von einer Radialkolbenpumpe gemäß einer dritten Ausführungsform der vorliegenden Erfindung;

Figur 5

zeigt eine vergrößerte Darstellung des Sprengrings in der Zylindersenkung; und

Figur 6

zeigt eine vergrößerte Darstellung des Sprengrings in der Nut.

Further advantages, features and details of the invention emerge from the subclaims and the following description, in which three exemplary embodiments are described in detail with reference to the drawings.

Figure 1

shows a piston and a plate from a conventional radial piston pump;

Figure 2

shows a piston and a plate of a radial piston pump according to a first embodiment of the present invention;

Figure 3

shows a piston and a plate of a radial piston pump according to a second embodiment of the present invention;

Figure 4

shows a piston and a plate of a radial piston pump according to a third embodiment of the present invention;

Figure 5

shows an enlarged view of the snap ring in the cylinder countersink; and

Figure 6

shows an enlarged view of the snap ring in the groove.

Figure 1 shows a section of a conventional Radial piston pump for high-pressure fuel generation Fuel injection systems for internal combustion engines. In figure 1 is only the part of the radial piston pump in section to which it is shown in the present invention arrives. The basic structure of a radial piston pump is for example from German patent DE 42 16 877 C2 is assumed to be known and is therefore only in the following briefly described.

The radial piston pump according to the invention is particularly in Common rail fuel injection systems for Diesel engines used. "Common rail" means so much like "common management", "common rail" or "common distribution bar". In contrast to conventional ones High pressure injection systems in which the fuel is over separate lines to the individual combustion chambers are promoted the injectors in common rail injection systems fed from a common line.

The section shown in Figure 1 Radial piston pump includes one in a pump housing mounted drive shaft with an eccentrically trained Shaft section. On the eccentric shaft section is a polygonal ring is provided against which the Shaft section is rotatable. The ring comprises several mutually offset flats against each other Piston 1 is supported. The pistons 1 are each in one Cylinder chamber 2 towards the drive shaft in the radial direction movably added.

As shown in Figure 1, is on the drive shaft directed end of the piston 1 attached to a plate 3. The Plate 3 is through a plate holder 4, also called a cage or spring plate is referred to, on the associated piston 1st held. In addition, the plate 3 is countered by a spring 5 pressed the ring (not shown). To prevent, that the plate holder 4 slips off the piston 1 is a snap ring 6 is mounted in a groove 7 of the piston 1.

Figure 2 is divided into Figures 2a, 2b and 2c. In Figure 2a is a section of an inventive Radial piston pump shown, which is the representation of figure 1 is similar in structure. Therefore simplicity the same for parts that appear in both figures Reference numerals used. In Figure 2b is the plate holder shown from Figure 2a alone. In Figure 2c is one View of the plate holder in the direction of arrow A in Figure 2a shown.

There is a plate 3 on the piston 1 shown in FIG. 1 appropriate. The plate 3 is supported by a plate holder 4 the piston 1 held. For this purpose there is a snap ring 6 mounted in a groove 7 on the circumference of the piston 1 is provided. In addition, the plate holder 4 by a Spring (see Figure 1) pressed against the snap ring 6.

The plate 3 has a blind hole 9 in the middle, into which one end of the piston 1 is positively received. The edge of the Blind hole 9 is provided with a cylinder countersink 26. The Cylinder countersink 26 is used to hold that part of the Snap ring 6, which protrudes from the groove 7.

The dimensioning of the snap ring 6 and the cylinder countersink 26 is shown enlarged in FIG. The tolerances are According to the invention chosen so that the snap ring 6 is always in the Lowering 26 lies. Dimension 1 is designed so that it is always smaller than dimension even with the most unfavorable tolerance position. 2. This locks the snap ring 6 in the depression 26 and cannot slide off the piston 1.

The dimensioning of the snap ring 6 and the groove 7 is in Figure 6 is shown enlarged. The tolerances of the groove 7 and of the snap ring 6 are chosen so that the snap ring 6 always in the groove base 60 and not at the edges 61, 62 of the groove 7. This prevents damage to the seat. Compared to the solution shown in Figure 1, the Wire diameter of the snap ring 6, the diameter of the Snap rings 6 and the diameter of the groove enlarged. Thereby a higher snap ring preload can be realized than in the solution shown in Figure 1.

In the radial piston pump shown in FIG. 2a, the Region of the plate holder 4 which bears against the piston 1, the shape of a round disc 20, which is radial to the Piston 1 extends. This ensures that the groove 7th can be viewed before the plate 3 in the Plate holder 4 is used. On the disc-shaped Area 20 borders a level 21 that is on the circumference of the round Washer 20 is formed. The plate 3 is with a Bevel 25 equipped, which is spaced from the stage 21 is.

Three snap segments 22 extend from step 20 parallel to the piston 1. The ends 23 of the snap segments 22 are first bent inwards and then slightly outwards. The inwardly curved piece of the snap segments 22 forms in the plate holder 4 an annular space, which is used to hold a Federal 24 is used, which is formed on the plate 3. The outwardly bent end pieces 23 of the snap segments 22 facilitate the insertion of the plate 3 in the plate holder 4th

In the embodiment shown in FIG. 3, as in FIG Figure 2a, only a portion of a piston 1 shown. The End of the piston 1 is received in a blind hole 9, the is mounted centrally in a plate 3. The plate 3 is held by a plate holder 4 on the piston 1. The Plate holder 4 is on the piston 1 by a snap ring 6 attached. The snap ring 6 is partially in a groove 7 of the Piston 1 and partially in a cylinder countersink 26 Plate 3 added. The plate holder 4 is around a rotating part on which a step 21 is formed. Of the stage 21 extends parallel to the piston 1 continuous collar 32. The edge of the collar 32 of the Plate holder 4 is provided with a bevel 40, which facilitates the assembly of the plate 3.

A groove 30 is attached to the circumference of the round plate 3, in a locking ring 31 is received. The locking ring 31 is resilient and can be used in the assembly of Plate 3 are pressed into the groove 30. That has the advantage, that the plate holder 4 with the continuous collar 32 and can be rigid.

In the section of another shown in FIG. 4 Embodiment of the radial piston pump according to the invention the plate holder 4, in contrast to that in FIG. 3 shown embodiment as a deep-drawn part with rounded Edges formed. In addition, the edge of the collar 32 of the Plate holder 4, as in that shown in Figure 3 Design, with a 40-bevel, which the Assembly of the plate 3 facilitated.

The only partially shown in Figures 1 to 6 Radial piston pump is used to remove fuel from a Pre-feed pump is delivered from a tank at high pressure to act upon. The high pressure fuel then becomes common in the above Supported distribution strip.

Claims (9)

1. Radial piston pump for the generation of high fuel pressure in fuel injection systems of internal combustion engines, in particular in a common-rail injection system, with a driveshaft which is mounted in a pump casing and which is designed eccentrically or has cam-like elevations in the circumferential direction, and with preferably a plurality of pistons (1) which are arranged in a respective cylinder space (2) radially with respect to the driveshaft and at whose ends facing the driveshaft is attached in each case a plate (3) which in the middle has a blind hole (9) in which the end of the associated piston (1) is received, the piston (1) having on its circumference a groove (7) in which is attached a spring ring (6), in order to fasten to the piston (1) a plate holder (4) which holds the plate (3) on the piston (1), characterized in that a cylindrical countersink (26) is formed at the edge of the blind hole (9) in the plate (3), the diameter of the cylindrical countersink (26) being dimensioned such that the play between the spring ring (6) and the circumference of the cylindrical countersink (26) is lower than the depth of the groove (7).
2. Radial piston pump according to Claim 1, characterized in that the radius of the groove (7) is greater than the wire radius of the spring ring (6).
3. Radial piston pump according to one of the preceding claims, characterized in that that region (20) of the plate holder (4) which bears against the spring ring (6) extends radially with respect to the piston (1) and is of plane design.
4. Radial piston pump according to one of the preceding claims, characterized in that a step (21) is formed radially on the outside on the plate holder (4) contiguously to a disc-shaped region (20).
5. Radial piston pump according to one of the preceding claims, characterized in that the plate (3) has on its circumference a groove (30) in which is received a securing ring (31) which bears against the plate holder (3).
6. Radial piston pump according to one of Claims 1 to 4, characterized in that snap segments (22) which bear against the circumference of the plate (3) are formed on the plate holder (3).
7. Radial piston pump according to Claim 6, characterized in that the ends (23) of the snap segments (22) are in each case bent slightly outwards.
8. Radial piston pump according to Claim 6, characterized in that the ends (40) of the snap segments (22) have in each case a bevel.
9. Radial piston pump according to one of the preceding claims, characterized in that a polygonal or cylindrical ring is arranged between the driveshaft and the plate (3).

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