High pressure pump

• US 7,108,491 B2
• Filed: 12/04/2003
• Issued: 09/19/2006
• Est. Priority Date: 02/11/2003
• Status: Expired due to Fees

• Current Assignee: Ganser-Hydromag AG
• Original Assignee: Ganser-Hydromag AG
• Inventors: Ganser, Marco
• Primary Examiner(s): Koczo, Jr., Michael
• Application Number:
  US10/544,004
• Publication Number:
  US 20060062677A1
• Time in Patent Office: 1,020 Days
• Field of Search: 92/72, 921/58, 921/59, 184/6.6, 417/228, 417/470
• US Class Current: 417/470
• CPC Class Codes: F02M 2200/16 Sealing of fuel injection apparatus not otherwise provided for
• CPC Class Codes: F02M 59/102 Mechanical drive, e.g. tappets or cams F02M45/063 takes precedence
• CPC Class Codes: F04B 1/0404 Details or component parts
• CPC Class Codes: F04B 1/0408 Pistons
• CPC Class Codes: F04B 1/0413 Cams
• CPC Class Codes: F04B 53/04 Draining

Abstract

A piston (6) of a piston pump unit (2), which can be displaced in a translatory manner, is guided in a cylinder bore (7). The piston (6) is driven by a crank drive (13) comprising an eccentric element (15) which is arranged on a drive shaft (14). A stroke ring (12) is rotationally mounted on the eccentric element (15) but does not rotate therewith. A sliding surface (10) of the piston (6) is arranged on a sliding bearing surface (11) on the stroke ring (12). A discharge chamber (22) is embodied inside the piston (6) on an end opposite the stroke ring (12). Said discharge chamber is open towards the sliding bearing surface (11). The discharge chamber (22) is connected in a pressure-wise manner to a working chamber (8) by means of a passage (23) in the piston (6). A displaceable control piston (25) is guided in a longitudinal bore (24) pertaining to said passage (23). Said control piston (25) is impinged upon on one side by a medium in the working chamber (8) and on the other front side by a pressure medium in the discharge chamber (22). The control piston (25) separates the medium which is to be transported from the pressure medium in the discharge chamber (22) and ensures that the pressure in the discharge chamber (22) increases if the pressure increases in the working chamber (8). This results in decompression of the sliding bearing between the piston (6) and the stroke ring (12).

Claims

1. A high pressure pump, in particular for a fuel injection system for internal combustion engines, having at least one piston pump unit (2, 2′

) which has a piston (6) guided in a cylinder bore (7) and delimiting a working chamber (8), having a crank drive (13) for driving the piston (6), having a stroke ring (12) which is arranged between the crank drive (13) and the piston (6) and which is mounted such that it is driven rotatably with respect to the crank drive (13) but does not rotate and which has a flat sliding bearing surface (11), on which the piston (6) is supported with a sliding surface (10), and having a relief chamber (22) which is arranged in the region of the sliding surface (10), is open toward the sliding bearing surface (11) and which has a pressure connection to the working chamber (8) via a passage (23) formed in the piston (6), characterized in that in the passage (23) in the piston (6) there is arranged a pressure transmission element (25, 41), which can be pressurized on one side by the medium to be delivered and on the opposite side by a pressure medium in the relief chamber (22), can be displaced in the direction of the application of pressure under the action of pressure and separates the relief chamber (22) fluidically from the working chamber (8).

2. The high pressure pump as claimed in claim 1, wherein the crank drive (13) has an eccentric element (15) which is arranged on a rotatably driven drive shaft (14) with an eccentricity (e) and on which the stroke ring (12) is mounted such that it does not corotate.

3. The high pressure pump as claimed in claim 1, wherein the pressure transmission element is a control piston (25), which can be displaced in a longitudinal bore (24) belonging to the passage (23) and is guided closely in a sliding manner.

4. The high pressure pump as claimed in claim 3, wherein, on its end facing the relief chamber (22), the control piston (6) is supported on a compression spring (26) which rests on an abutment at the other end.

5. The high pressure pump as claimed in claim 4, wherein the abutment is formed by a supporting element retained in the control piston (25), in particular a spring ring (27).

6. The high pressure pump as claimed in claim 1, wherein the pressure transmission element is a diaphragm (41) which can be deflected elastically, which covers the passage (23) and is fixed in a sealing manner in its edge region.

7. The high pressure pump as claimed in claim 6, wherein the piston (6) has a piston element (38) guided in the longitudinal bore (7) and a ring (39) which is connected to the piston element (38) at the end of the latter facing away from the working chamber (8).

8. The high pressure pump as claimed in claim 7, wherein the diaphragm (41) is held firmly in its edge region between the piston element (38) and the ring (39).

9. The high pressure pump as claimed in claim 3, wherein in the piston (6) there is formed an annular groove (36) which surrounds the relief chamber (22) and is coaxial with the latter, which is open toward the sliding bearing surface (11) and which is connected to a chamber (5) in which the crank drive (13) and the stroke ring (12) are accommodated.

10. The high pressure pump as claimed in claim 9, wherein in the stroke ring (12), in the region of the sliding bearing surface (11), there is formed a longitudinal groove (37) which is open toward the sliding surface (10) and opens into the chamber (5), is offset with respect to the relief chamber (22) in the direction of the axis of rotation (14a) of the drive shaft (14) and communicates with the annular groove (36).

11. The high pressure pump as claimed in claim 1, wherein the pressure medium in the relief chamber (22) is a lubricant, preferably lubricating oil.

12. The high pressure pump as claimed in claim 11, wherein in the stroke ring (12) there is formed a connecting duct (34, 35), which opens into the sliding bearing surface (11) at a point such that it is connected to the relief chamber (22) only in specific positions of the stroke ring (12) with respect to the piston (6) and which can be connected periodically to a lubricant feed conduit (31, 32, 33).

13. The high pressure pump as claimed in claim 12, wherein, at the other end, the connecting duct (34, 35) opens into the inner surface (12a) of the stroke ring (12) which is in contact with the eccentric (15) of the crank drive (13), and in that on the circumference of the eccentric (15) there is provided a lubricating groove (31) which extends over part of its circumference and is open toward the outside and is connected to a lubricant source via a connecting line (32, 33) running in the eccentric (15) and in the drive shaft (14), the lubricating groove 31 being arranged such that it is connected to the connecting duct (34, 35) in the stroke ring (12) when this connecting duct (34, 35) is connected to the relief chamber (22).

14. The high pressure pump as claimed in claim 1, wherein in the wall of the cylinder bore (7) there is formed an annular collecting groove (28) which is open toward the piston (6), is used to collect seepage which passes through the gap between the wall of the cylinder bore (7) and the piston (6) and to which a discharge conduit (30) is connected.

15. The high pressure pump as claimed in claim 14, wherein in the piston (6) there is a transverse bore (29) which leads from the longitudinal bore (24) in the piston (6) to the outer wall of the latter, opens into the annular collecting groove (28) and is used to carry away seepage which passes through the gap between the wall of the longitudinal bore (24) and the control piston (25).

16. The high pressure pump as claimed in claim 1, wherein the high pressure pump (1, 1′

) is designed to deliver fuel, in particular diesel fuel.

17. The high pressure pump as claimed in claim 1, wherein the piston (6) is provided at its end opposite the working chamber (8) with a base part (9) in which the relief chamber (22) is formed.

18. The high pressure pump as claimed in claim 17, wherein the diameter of the relief chamber (22) is bigger than the diameter of the passage (23) in the piston (6).

19. The high pressure pump as claimed in claim 18, wherein the diameter of the relief chamber (22) is bigger than the diameter of a longitudinal bore (24) which is part of the passage (23).

20. The high pressure pump as claimed in claim 1, wherein the diameter of the passage (23) in the piston (6) is the same throughout the entire length of the passage (23).