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Title:
VACUUM PUMP
Document Type and Number:
WIPO Patent Application WO/2016/150505
Kind Code:
A1
Abstract:
The invention refers to a mechanical automotive vacuum pump (10) with a housing arrangement (9) enclosing a pumping chamber (11) and rotatably supporting a pump rotor (16) with a rotor body (22) with a bearing section (35) and a chamber section (36). The rotor body (22) is at the chamber section (36) provided with a radial vane slit (19) wherein a radially shiftable pump vane (18) is supported. The rotor body (22) is at the bearing section (35) provided with a cylindrical bearing surface (39) which defines together with a cylindrical bearing surface (37) of the housing arrangement (9) a friction bearing (38). The rotor body bearing section (36) is provided with a circular lubrication ring groove (60) and the housing bearing surface (37) is provided with a corresponding lubrication inlet opening (66) lying in the same transversal plane as the ring groove (60) and opposite to the ring groove (60). The inlet opening (64) is directly connected to a lubricant pump connector (70) at the housing arrangement (9) of the vacuum pump (10).

Inventors:
PERONI GIORGIO (IT)
SQUARCINI RAFFAELE (IT)
ARMENIO GIACOMO (IT)
Application Number:
EP2015/056452
Publication Date:
September 29, 2016
Filing Date:
March 25, 2015
Export Citation:
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Assignee:
PIERBURG PUMP TECHNOLOGY GMBH (DE)
International Classes:
F04C18/344; F04C29/02
Foreign References:
FR2815088A12002-04-12
FR2640699A11990-06-22
FR2845735A12004-04-16
Attorney, Agent or Firm:
PATENTANWÄLTE TER SMITTEN EBERLEIN RÜTTEN (DE)
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Claims:
C L A I M S

1. Mechanical automotive vacuum pump (10) with a housing arrangement (9) enclosing a pumping chamber (11) and rotatably supporting a pump rotor (16) with a rotor body (22) with a bearing section (35) and a chamber section (36), wherein

the rotor body (22) is at the chamber section (36) provided with a radial vane slit (19) wherein a radially shiftable pump vane (18) Is supported and is at the bearing section (35) provided with a cylindrical bearing surface (39) which defines together with a cylindrical bearing surface (37) of the housing arrangement (9) a friction bearing (38),

the rotor body bearing section (35) is provided with a circular lubrication ring groove (60) and the housing bearing surface (37) is provided with a corresponding lubrication inlet opening (66) lying in the same transversal plane as the ring groove (60) and opposite to the ring groove (60), and

the inlet opening (66) is directly connected to a lubricant pump connector (70) at the housing arrangement (9) of the vacuum pump (10).

2. Mechanical automotive vacuum pump (10) of claim 1, wherein the lubrication ring groove (60) is fluidically connected to the vane slit (19) by a connection channel (62) for fluidically connecting the ring groove (60) and the vane slit (19).

3. Mechanical automotive vacuum pump (10) of claim 2, wherein the connection channel (62) is an axial connection groove at the rotor body (22).

4. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the lubrication ring groove (60) is axially located closer to the chamber-sided end of the friction bearing (38) then to the other axial end of the friction bearing (38), and is preferably located in the first axial third of the friction bearing (38).

5. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the rotor body diameter (dR) of the cylindrical chamber section (36) is identical with the rotor body diameter (dB) of the cylindrical bearing section (35) so that the radial surface of the rotor body (22) defines a stepless cylinder over the entire rotor body length.

6. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the rotor body (22) Is made out of plastic.

7. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein only one single radial friction bearing (38) is provided so that only one axial end of the pump rotor (16) is radially supported whereas the other axial end of the pump rotor (16) is not radially supported.

8. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the vane silt (19) is axially open at one axial slit end so that one axial front end of the vane (18) is axially in direct axial contact with the housing arrangement (9), preferably with a housing cover lid (14).

9. Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the bearing section (35) of the pump rotor body (22) is provided with an axial bearing ring surface (42) which is axially supported by a corresponding axial bearing ring surface (41) of the housing arrangement (9).

Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the vane slit (19) is defined by a separate slit body (20) made out of metal which is inserted into the plastic rotor body (22).

Mechanical automotive vacuum pump (10) of one of the preceding claims, wherein the bearing section (35) of the pump rotor body (22) is provided with a mechanical coupling structure (50) which allows to mechanically couple the pump rotor (16) to a corresponding driving means.

Description:
VACUUM PUMP

The invention is directed to a mechanical automotive vacuum pump with a housing arrangement enclosing a pumping chamber and rotatably supporting a pump rotor.

A mechanical automotive vacuum pump is mechanically driven by the engine of the automotive vehicle. The automotive engine is, in most cases, an internal combustion engine.

EP 0 264 749 A2 discloses an automotive vacuum pump with a pump rotor with a chamber section and a bearing section. The rotor body is provided with a cylindrical bearing surface which together with a corresponding bearing surface of the pump housing defines a friction bearing at one axial end of the pump rotor. The pump lubrication is realized by lubricant which is first injected Into the rotor interior. From the rotor interior the lubricant is pressed via gaps between the pump rotor and the vane or the pump housing into the pumping chamber. From the pumping chamber the lubricant is pumped together with the pressurized air through an air outlet into an outlet chamber. From the outlet chamber, the lubricant is pumped into a circular ring groove which is provided at the cylindrical bearing surface of the pump housing. The lubricant pressure at the friction bearing directly depends, among others, on the pneumatic outlet pressure of the pump.

It is an object of the invention to improve the quality and reliability of the pneumatic sealing of a mechanical automotive vacuum pump. This object is achieved with a mechanical automotive vacuum pump with the features of claim 1.

According to claim 1, the vacuum pump is provided with a housing arrangement enclosing a pumping chamber. The housing arrangement rotatably supports a pump with a rotor body which is functionally separated, seen in axial direction, into a bearing section and a chamber section. At the chamber section the rotor body is provided with a radial vane slit wherein a radially shiftable pump vane is supported. At the bearing section the rotor body is provided with a cylindrical bearing surface which defines together with a corresponding cylindrical bearing surface of the housing arrangement a radial friction bearing. At the rotor body bearing section a circular lubrication ring groove is provided. At the housing-sided bearing surface a corresponding lubrication inlet opening is provided which lies in the same transversal plane as the ring groove and is arranged radially directly opposite to the ring groove.

The inlet opening opposite the ring groove is fluidically directly connected to a lubricant pump con ector at the housing arrangement of the vacuum pump. The lubricant pump connector is not provided at a rotating part of the vacuum pump but is provided at a non-rotating part of the vacuum pump. The term "fluidically directly connected" here means that the lubricant coming from the lubricant pump connector is substantially air- free and substantially has the fluidic pressure as delivered from a lubricant pump to the vacuum pump. The air-free lubricant flows from the inlet opening into the ring groove.

This arrangement guarantees that the lubricant pressure at the friction bearing directly corresponds to the lubricant pressure as provided by the lubricant pump at the lubricant pump connector of the vacuum pump housing arrangement. This makes sure that the friction bearing is always lubricated with a constant and relatively high lubricant pressure. Since the lubricant at the friction bearing has a relatively high pressure level, it can be avoided that the lubricant pressure in the friction bearing falls below the pneumatic pressure in the pumping chamber. As a consequence, no pressurized air from the pumping chamber flows into the bearing gap of the friction bearing so that a reliable, tight and good pneumatic sealing of the pumping chamber is realized in this area of the vacuum pump.

According to a preferred embodiment, the lubrication ring groove is fluidicaily connected to the vane slit by a connection channel for fluidically connecting the ring groove and the vane slit. The connection channel can be realized as an axial connection groove at the outside surface of the rotor body. The connection channel provides a lubricant supply for the vane section of the rotor body so that the gaps between the radial vane slit and the pump vane are filled with high pressure lubricant.

Preferably, the lubrication ring groove is axia!ly located closer to the chamber-sided end of the friction bearing then to the other axial end of the friction bearing. Preferably, the lubricant ring groove is located in the first axial third of the friction bearing so that the lubrication ring groove is arranged much closer to the chamber section then to the coupling-sided axial end of the rotor body. The closer the lubrication ring groove is located to the chamber section, the better is the pneumatic sealing quality in this area of the friction bearing.

According to a preferred embodiment of the invention, the rotor body diameter dR of the cylindrical chamber section is Identical with the rotor body diameter dB of the cylindrical bearing section so that the radial surface of the rotor body defines a stepless cylinder over substantially the entire rotor body length. The cylindrical rotor body is relatively simple and cost-effective in production. Since the diameter of the friction bearing is relatively high, the mechanical quality of the friction bearing Is relatively high, as well.

Preferably, the rotor body is made out of plastic and is produced by Injection molding. A plastic rotor body is relatively light so that acceleration and deceleration of the pump rotor is not as energy- consuming as it would be with a metal rotor body. As a consequence, the mechanical coupling structure of the vacuum pump is mechanically better protected against wearout and damaging.

Preferably, only one single radial friction bearing is provided so that only one axial end of the pump rotor is radially supported whereas the other axial end section of the pump rotor is not radially supported by a radial bearing. The pump rotor is provided with a cantilever bearing structure. Since only one single radial bearing is provided, the structure of the vacuum pump is simplified and thereby more cost effective in production.

Preferably, the vane slit is axlally open at one axial silt end so that one axial front end of the vane is axially in direct axial contact with the housing arrangement, preferably with a housing cover lid.

According to another preferred embodiment of the invention, the pump rotor body is provided with an axial bearing ring surface which Is axially supported by a corresponding axial bearing ring surface of the housing arrangement. The two bearing ring surfaces together define an axial friction bearing which is arranged at the axial rotor end opposite the rotor chamber section. Radially Inside the ring -like axial friction bearing no housing wall Is provided so that a mechanical coupling structure at this axial end of the rotor body is accessible for a corresponding coupling structure of a driving means. When the vacuum pump has been assembled to a automotive engine, the corresponding coupling structure mechanically drives the pump rotor via the pump coupling structure.

Preferably, the vane slit is defined by a separate slit body made out of metal which Is inserted into and is fixed at the plastic rotor body. The plastic rotor body allows to have a relatively light pump rotor body, whereas the metal slit body guarantees a durable and persistent support structure for the shiftable pump vane.

One embodiment of the mechanical automotive vacuum pump according to the invention is explained with reference to the enclosed drawing. The drawing shows a longitudinal cross section of a mechanical automotive vacuum pump.

The figure shows a mechanical automotive vacuum pump 10 which provides a total pressure of below 100 mbar for supplying, for example, a 5 pneumatic braking servo device with low pressure. The mechanical vacuum pump 10 is mechanically driven by an automotive engine, for example by an Internal combustion engine.

The vacuum pump 10 comprises a static housing arrangement 9 which supports and substantially houses a rotatable pump rotor 16. The housing lo arrangement 9 comprises a complex main body 12 for radially enclosing the pump rotor 12 and a separate cover lid 14 for axially closing one axial end of the housing arrangement 9.

The pump rotor 16 comprises a plastic pump rotor body 22 with a substantially cylindrical and stepless outer surface over the entire axial 15 length of the rotor body 22. As a consequence, the outer cylindrical diameter dR of the rotor body 22 at the chamber section 36 is identical with the outer cylindrical diameter dB of the rotor body 22 at the bearing section 35.

The rotor body 22 is axially provided with two functional partitions, namely 20 the bearing section 35 and the chamber section 36. In the chamber section 36, the rotor body 22 is provided with a vane slit 19 for supporting a radially shiftab!e pump vane 18 which is co- rota ting with the rotor body 22 in a pumping chamber 11 defined by the housing main body 12. The vane slit 19 is, in this embodiment, defined by a separate metal slit body 25 20 which is fixed to the plastic rotor body 22.

In the bearing section 35, the rotor body 22 Is provided with a cylindrical bearing surface 39 which defines together with a corresponding cylindrical bearing surface 37 of the housing main body 12 a radial friction bearing 38. The rotor body 22 is supported can til eve red so that only one single 30 axial end of the pump rotor 16 is supported by a radial bearing 38, whereas the other axial end of the pump rotor 16 is not provided with a radial bearing .

The bearing-sided front end of the rotor body 22 Is provided with an axial bearing ring surface 42 which is axially supported by a corresponding axial bearing ring surface 41 defined by the housing main body 12. The bearing ring surfaces 41, 42 together define an axial friction ring bearing. The center of the bearing-sided front end of the rotor body 22 is provided with a coupling structure 54 for coupling a corresponding coupling structure of a pump driving means, The other front end of the rotor body 22 is axially supported by the cover lid 14,

The rotor body 22 is provided with a circular lubrication ring groove 60 at the beari g section 35. The ring groove 60 is arranged axially close to the chamber section 36 of the rotor body 22, and is, in the present embodiment, arranged in the first axial fourth of the friction bearing 38 adjacent to the chamber section 36. The outer surface of the rotor body 22 Is also provided with an axial connection channel 62 and the metal slit body 20 is provided with a continuing axial connection channel 64 so that a fluidic connection is provided between the ring groove 60 and the vane slit 19 via the axial connection channels 62, 64.

The housing-sided radial bearing surface 37 is provided with a lubricant inlet opening 66 radially opposite to the ring groove 60 and thereby lying in the same transversal plane as the ring groove 60. The inlet opening 66 is fluidically and directly connected to a lubricant pump connector 70 at the housing main body 12 via a lubricant channel 68 within the housing main body 12. When the vacuum pump 10 is mounted to the automotive engine, the lubricant pump connector 70 Is fluidically connected to a lubricant pump 74 via a lubricant conduit 72. The lubricant pump 74 pumps a liquid lubricant from a lubricant tank 76 to the lubricant pump connector 70 of the vacuum pump 10.

When the lubricant pump 74 Is pumping, the lubricant is pumped to the lubricant pump connector 70, and is pumped via the lubricant channel 68 and the inlet opening 66 directly to the ring groove 60. The lubricant thereby fills the cylindrical gap between the bearing surfaces 37, 39 of the friction bearing 38 and then flows into the pumping chamber 11. A fraction of the lubricant flows via the connection channels 62, 64 to the vane slit 19 thereby lubricating the gaps between the pump vane 18 and the vane slit 19.




 
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