WO2009138264A1

WO2009138264A1 - Radial piston pump

Info

Publication number: WO2009138264A1
Application number: PCT/EP2009/052960
Authority: WO
Inventors: Nestor Rodriguez-Amaya; Gernot Repphun
Original assignee: Robert Bosch Gmbh
Priority date: 2008-05-13
Filing date: 2009-03-13
Publication date: 2009-11-19
Also published as: DE102008001713A1

Abstract

The invention relates to a radial piston pump comprising at least one piston (15) that is driven by an eccentric element via a polygonal ring having at least one flat section (31). In order to create a radial piston pump that can be produced in a cost-effective way and has a long service life, the flat section (31) is optimized with respect to lubrication, cooling and/or reduction of the frictional forces occurring during operation of the radial piston pump (1) on the flat section (31).

Description

Description Radial piston pump

The invention relates to a radial piston pump with at least one piston, which is driven by an eccentric element via a polygonal ring, which has at least one flattening.

Disclosure of the invention

The object of the invention is to provide a radial piston pump according to the preamble of claim 1, which is inexpensive to produce and has a long service life.

The object is in a radial piston pump with at least one piston, which is driven by an eccentric via a polygonal ring having at least one flattening, triggers that the flattening in terms of lubrication, cooling and / or reducing the operation of the radial piston pump is optimized at the flattening frictional forces. The radial piston pump preferably comprises a plurality of pistons having a NEN piston which rests against one of a plurality of flats of the polygon ring. It is also possible that between the piston, in particular the piston foot, and the flattening an intermediate element is arranged. The intermediate element may be a bucket tappet, as known from German Patent DE 198 44 326 B4. Targeted introduction of lubricant, in particular in a suction phase of the radial piston pump, to at least one contact point of the flattening can significantly improve the contact temperature and the lubrication and thus the wear behavior. The suction phase is the phase in which the radial piston pump sucks in a medium, preferably fuel, which is or is subjected to high pressure in a pressure phase in the radial piston pump.

A preferred embodiment of the radial piston pump is characterized in that the flattening in a Saugkontaktflächenabschnitt has a surface texture which favors a supply of lubricant. A suction contact surface section is a region of the flattening which comes into contact with the piston foot or the intermediate element substantially only in the suction phase. In the suction phase, a lower pressure force acts between the piston and the associated flattening of the radial piston pump.

A further preferred exemplary embodiment of the radial piston pump is characterized in that the flattening in the suction contact surface section is provided with at least one bevel, at least one depression and / or at least one lubricant supply channel. The skew, recess or the Schmiermittelzuführkanal serves to absorb or guide lubricant in the suction phase.

A further preferred embodiment of the radial piston pump is characterized in that the flattening in the Saugkontaktflächenabschnitt has a surface structure that allows a feeding lubricant. The surface structure may, for example, depressions, grooves, grooves and / or holes in any shape. The surface structure may also have elevations.

Another preferred exemplary embodiment of the radial piston pump is characterized in that the flattening in the suction contact surface section has at least one support section which does not have a bevel and / or recess and / or

Surface structure is provided. This prevents unwanted tilting of the piston in the suction phase.

A further preferred exemplary embodiment of the radial piston pump is characterized in that the flattening in the suction contact surface section has a different surface finish than in a pressure contact surface section. A pressure contact surface section is a region of the flattening which comes into contact with the piston foot or the intermediate element substantially only in a pressure phase. In the printing phase, the compressive force acting between the piston and the flattening is significantly greater than in the suction phase. - A -

Another preferred embodiment of the radial piston pump is characterized in that the flattening in the Saugkontaktflächenabschnitt falls away from the pressure contact surface portion or increases. As a result, a clearance between the piston foot or the intermediate element and the flattening is created in a simple manner, which allows the supply of lubricant in the Saugkontaktflächenabschnitt.

Another preferred exemplary embodiment of the radial piston pump is characterized in that the transition between the suction contact surface section and the pressure contact surface section is optimized with regard to the supply of lubricant. The transition may, for example, be logarithmic.

A further preferred exemplary embodiment of the radial piston pump is characterized in that the flattening in the pressure contact surface section has at least one lubricant distribution channel. For example, the lubricant distribution channel may have a plurality of branches through which the lubricant is distributed over the entire pressure contact surface portion.

A further preferred embodiment of the radial piston pump is characterized in that the flattening in the pressure contact surface section has a surface structure which promotes a feeding and / or distribution of lubricant. The surface structure may include, for example, depressions, grooves, grooves and / or holes in have a lovely shape. The surface structure may also have elevations.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Short description of the drawing

Show it:

Figure 1 is a greatly simplified representation of a radial piston pump in cross section through a drive element;

Figure 2 shows a detail of Figure 1 according to a first embodiment;

3 shows a flattening of Figure 2 in plan view;

Figure 4 is a similar view as in Figure 2 according to another embodiment with a sloping slope;

FIG. 5 shows a representation similar to that in FIGS. 2 and 4 according to a further exemplary embodiment with different surface structures;

Figure 6 is a flattening of Figure 5 in plan view; Figure 7 shows different surface structures in plan view and

FIG. 8 shows a representation similar to that in FIGS. 2, 4 and 5 according to another

Embodiment with a rising slope.

Description of the embodiments

In Figure 1, a radial piston pump 1 is shown greatly simplified in section. The radial piston pump is preferably a fuel injection pump in which fuel is subjected to high pressure. The fuel acted upon by high pressure is injected, for example via fuel injectors, into at least one combustion chamber of an internal combustion engine.

The radial piston pump 1 is driven via an eccentric element 2 by a drive shaft. The eccentric element 2 interacts with a polygon ring 4, which has a central receptacle for the eccentric element 1 inside. On the outside, the polygonal ring 4 is provided with three flattened portions 11, 12, 13, which serve to convert a rotational movement of the drive shaft into an oscillating movement of a piston 15. The piston 15 has at one end a piston foot 16 which bears against the flat 11.

A double arrow 18 indicates how the polygon ring 4 moves with the flattening 11 relative to the piston 15 when the eccentric element 2 is driven via the drive shaft. Through the polygon ring 4, a rotational movement of the drive shaft is converted into an oscillating movement of the piston 15. By a dashed piston 25 with a likewise dashed piston 26 is indicated that the piston with different points of the flat 11 comes into contact when the polygon ring 4 is driven by the eccentric 2. The structure and function of such a radial piston pump is disclosed, for example, in German Patent DE 198 44 326 B4. In the known radial piston pump, a bucket tappet is disposed between the piston and the polygon ring.

In the power transmission between the polygon ring 4 and the piston 15, there is a reversibly sliding surface tribological contact, which is limited by wear in the contact, especially at high frequencies. At the contact points, high loads are transmitted over a large contact area at relatively low contact pressures. In the illustrated radial piston pump 1, the sliding movement takes place during the pressure build-up and the delivery phase of the pump under high load and in the suction phase under low load.

According to one essential aspect of the invention, lubricant is introduced to the contact point in the suction phase. As a result, the contact temperature and the lubrication can be significantly improved. Furthermore, the curve 20 of the pressure p over time is plotted in FIG. 1 in a Cartesian coordinate diagram. The pressure decreases in the delivery stroke the piston 15, reaches a maximum value and then drops again.

FIGS. 2 and 3 show a flattening 31 on which a piston foot 16 of a piston 15 abuts flatly. The contact surface of the flattening 11 is spatially divided into a Saugkontaktflächenab- section 34 and a pressure contact surface portion 35. The pressure contact surface portion 35 is used in the delivery phase of the piston 15 to support the hydraulic pressure. The Saugkontakt- surface portion 34 is only in the suction phase of the piston 15 with the piston 16 in contact. Therefore, the burden is significantly lower. The loading is preferably only the pretensioning force of a return spring, by means of which the piston foot 16 of the piston 15 is held in contact with the flattening 11.

In conventional radial piston pumps, the piston foot 16 has its entire surface in contact with the flattening 11. Thus, frictional heat can not be transported out of the contact by lubricant. According to an essential aspect of the invention, the contact in Saugkontakt- surface section 34 is deliberately reduced in order to improve the supply or supply of lubricant. In the exemplary embodiment illustrated in FIGS. 2 and 3, the pressure-contact-surface section 35 is provided with a surface structure 36 for this purpose. The Saugkontakt- surface portion 34 is provided with a different surface structure 37. Furthermore, in the suction contact surface section 34, a lubricant supply is provided. provided guide channel 38 which is provided with a skew, as indicated by an angle α in Figure 2.

In the exemplary embodiment illustrated in FIG. 4, a flattening 41 with a suction contact surface section 44 and a pressure contact surface section 45 is shown. The complete Saugkon- contact surface portion 34 is provided with a slope 48, as indicated by an angle α. The skew 48 drops away from the pressure contact surface section 45. The bevel 48, like the lubricant supply passage 38 in FIG. 3, allows lubricant to be introduced into the contact between the piston 15 and the flattening 31 during suction phase. 41 arrived. As a result, in particular the contact surface of the piston foot 16 can be cooled. By a targeted transition of the lowered surface, for example logarithmic, the lubrication of the contact can be further improved. In order to prevent the piston base 16 from tilting in the suction phase, partial regions, for example webs or a remaining edge region in the suction region, may be provided in the suction contact surface section 34; 44 support.

FIGS. 5 and 6 show a flattening 51 with a suction contact surface section 54 and a pressure contact surface section 55. The pressure contact surface portion 55 is provided with a surface structure 56. The suction contact surface portion 54 is provided with a surface structure 57. The surface structures 56, 57 are used to contact only in the suction phase small load by reducing the contact surface targeted to lubricate and cool.

FIG. 7 shows further surface structures which are preferably provided in the suction contact surface section 54.

FIG. 8 shows a flattening 61 with a suction contact surface section 64 and a pressure contact surface section 65. The Saugkontakt- surface portion 64 is provided with a slope 68 which rises away from the pressure contact surface portion 65, as indicated by an angle ß. By raising or chamfering the Saugkontaktflächenabschnitts 64 is achieved that only a portion of the piston foot 16 has contact with the flattening 61. The resulting clearance between the piston root 16 and the flattening 61 enables the supply and distribution of lubricant.

Claims

claims

1. Radial piston pump with at least one piston (15) which is driven by an eccentric element (2) via a polygonal ring (4) which has at least one flattening (11-13; 31; 41; 51; 61), characterized in that the flattening (31; 41; 51; 61) is optimized with regard to lubrication, cooling and / or reduction of the frictional forces occurring during operation of the radial piston pump (1) on the flattening (31; 41; 51; 61).

A radial piston pump according to claim 1, characterized in that the flattening (11-13; 31; 41; 51; 61) in a suction contact surface portion (34; 44; 54; 64) has a surface finish which promotes supply of lubricant.

3. Radial piston pump according to claim 2, characterized in that the flattening (31; 41; 61) in the

Suction contact surface portion (34; 44; 64) with at least one bevel (48; 68), at least one recess and / or at least one lubricant supply channel (38) is provided.

4. Radial piston pump according to claim 2 or 3, characterized in that the flattening (31; 51) in the Saugkontaktflächenabschnitt (34; 54) an O- has surface structure (37, 57), which allows a lubricant to be brought forward.

5. Radial piston pump according to one of claims 2 to 4, characterized in that the flattening (11-

13; 31; 41; 51; 61) in the Saugkontaktflächenabschnitt has at least one support portion which is not provided with a skew and / or depression.

A radial piston pump according to any one of claims 2 to 5, characterized in that the flattening (11-13; 31; 41; 51; 61) in the suction contact surface portion (34; 44; 54; 64) has a different surface finish than in a pressure contact surface portion (35; 45; 55; 65).

A radial piston pump according to claim 6, characterized in that the flattening (41; 61) in the suction contact surface portion (44; 64) decreases or increases away from the pressure contact surface portion (45; 65).

8. A radial piston pump according to claim 6 or 7, characterized in that the transition between the suction contact surface portion (34; 44; 54; 64) and the pressure contact surface portion (35; 45; 55; 65) is optimized with respect to lubricant supply.

9. Radial piston pump according to one of claims 6 to 8, characterized in that the flattening (11- 13; 31; 41; 51; 61) in the pressure contact surface portion (35; 45; 55; 65) has at least one lubricant distribution channel.

10. Radial piston pump according to one of claims 6 to 9, characterized in that the flattening

(11-13; 31; 41; 51; 61) have a surface structure in the pressure contact surface portion (35; 45; 55; 65)

(36; 56), which promotes a supply and / or distribution of lubricant.