U.S. patent application number 17/153687 was filed with the patent office on 2021-07-22 for friction-optimized vacuum orbiter pump.
The applicant listed for this patent is NIDEC GPM GmbH. Invention is credited to Conrad Nickel, Franz Pawellek, Jakob Schnitzer.
Application Number | 20210222694 17/153687 |
Document ID | / |
Family ID | 1000005361444 |
Filed Date | 2021-07-22 |
United States Patent
Application |
20210222694 |
Kind Code |
A1 |
Nickel; Conrad ; et
al. |
July 22, 2021 |
Friction-Optimized Vacuum Orbiter Pump
Abstract
The present invention relates to a dry-running, oil-free orbiter
vacuum pump, on which a friction-optimized surface is provided on
components. The dry-running orbiter vacuum pump comprises inter
alia a pump housing with a cylindrical pump chamber and an orbiter
eccentric piston with a guide slot and a cylindrical exterior
surface, a cylindrical cross-section of the orbiter eccentric
piston being smaller than a cylindrical cross-section of the pump
chamber. At at least one of a radial air gap and an axial air gap
formed in the cylindrical pump chamber between the orbiter
eccentric piston and the pump housing at least one sliding surface
is arranged in a manner exposed to the air gap; wherein the at
least one sliding surface comprises a microstructure including
cavities for decreasing an exposed surface of the at least one
sliding surface.
Inventors: |
Nickel; Conrad; (Troistedt,
DE) ; Schnitzer; Jakob; (Hildburghausen, DE) ;
Pawellek; Franz; (Lautertal, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIDEC GPM GmbH |
Auengrund OT Merbelsrod |
|
DE |
|
|
Family ID: |
1000005361444 |
Appl. No.: |
17/153687 |
Filed: |
January 20, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 25/02 20130101;
F04C 18/04 20130101; F04C 2230/22 20130101; F04C 29/0057 20130101;
F04C 2230/92 20130101; F04C 2220/12 20130101 |
International
Class: |
F04C 25/02 20060101
F04C025/02; F04C 18/04 20060101 F04C018/04; F04C 29/00 20060101
F04C029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 21, 2020 |
DE |
10 2020 101 311.6 |
Claims
1. A dry-running orbiter vacuum pump comprising: a pump housing
with a cylindrical pump chamber; an orbiter eccentric piston with a
guide slot and a cylindrical exterior surface, a cylindrical
cross-section of the orbiter eccentric piston being smaller than a
cylindrical cross-section of the pump chamber; a shaft for driving
the orbiter eccentric piston by means of an eccentric crankpin that
meshes with the orbiter eccentric piston; a blocking slide received
in the guide slot of the orbiter eccentric piston, one end of the
blocking slide being pivotably mounted at the pump housing between
an inlet and an outlet; characterized in that at at least one of a
radial air gap and an axial air gap formed in the cylindrical pump
chamber between the orbiter eccentric piston and the pump housing
at least one sliding surface is arranged in a manner exposed to the
air gap; wherein the at least one sliding surface comprises a
microstructure including cavities for decreasing an exposed surface
of the at least one sliding surface.
2. The dry-running orbiter vacuum pump according to claim 1,
wherein the cavities of the microstructure have a closed contour
towards the surface of the at least one sliding surface.
3. The dry-running orbiter vacuum pump according to claim 1,
wherein the cavities of the microstructure have a dimension of 10
to 100 .mu.m in a depth direction to the surrounding surface of the
at least one sliding surface.
4. The dry-running orbiter vacuum pump according to claim 1,
wherein the cavities of the microstructure have a dimension of 10
to 1000 .mu.m in an extension direction of a contour to the
surrounding surface of the at least one sliding surface.
5. The dry-running orbiter vacuum pump according to claim 1,
wherein the cavities of the microstructure have the shape of a
spherical cap, of an ellipsoid spherical cap, of an elongated hole
or of a groove.
6. The dry-running orbiter vacuum pump according to claim 1,
wherein the microstructure of the at least one sliding surface is
produced at the corresponding surface of the pump housing or of the
orbiter eccentric piston by means of laser-assisted melting of the
material.
7. The dry-running orbiter vacuum pump according to claim 1,
wherein a material, on which the microstructure of the at least one
sliding surface is produced, is provided as a surface insert that
is inserted into a component body of the pump housing or of the
orbiter eccentric piston.
8. The dry-running orbiter vacuum pump according to claim 1,
wherein the microstructure of the at least one sliding surface is
produced on a metal material provided by the pump housing or by the
orbiter eccentric piston.
9. The dry-running orbiter vacuum pump according to claim 8,
wherein the metal material, on which the microstructure of the at
least one sliding surface is produced, is surface hardened by means
of hard anodizing.
10. The dry-running orbiter vacuum pump according to claim 8,
wherein the metal material, on which the microstructure of the at
least one sliding surface is produced, is provided as a sintered
layer sintered onto a material of the pump housing or of the
orbiter eccentric piston.
11. The dry-running orbiter vacuum pump according to claim 1,
wherein the at least one sliding surface is additionally also
arranged at at least one surface of the blocking slide, wherein the
at least one sliding surface at the blocking slide also comprises
the microstructure including cavities for decreasing an exposed
surface of the at least one sliding surface.
Description
[0001] The present invention relates to a dry-running, oil-free
orbiter vacuum pump, on which a friction-optimized surface is
provided on components.
[0002] Vacuum pumps serve to evacuate gaseous media, such as e.g.
for the purpose of generating a vacuum in a braking force booster.
In the automotive sector, further applications of dry-running
vacuum pumps also include e.g. the pneumatic adjustment of exhaust
gas recirculation valves, exhaust flaps, guide vanes on
turbochargers having a variable turbine geometry, and of a bypass
for charging pressure regulation with a waste gate, and include the
actuation of a central locking system, or for opening and closing
headlight covers. In plant construction, dry-running vacuum pumps
can serve in general to produce negative pressure in
electro-pneumatic valves or pneumatic actuators.
[0003] Rotary displacement pumps, such as e.g. vane pumps or rotary
vane pumps, are predominantly known for this purpose in the prior
art and are very widely used. Some pumps require the provision of a
lubricating film between the rotating and stationary pump
components in order to ensure a sufficiently gas-tight seal as well
as low frictional wear on contact surfaces. The requirement for a
lubricating film in a vacuum pump gives rise to problems in terms
of the temperature-dependent viscosity of the lubricant and the
contamination caused by absorption of particles from the discharged
air. These disadvantages are brought to bear under fluctuating
ambient conditions of a mobile application and in particular to an
increased extent in an installation in an engine compartment of a
vehicle. Moreover, such pumps must always be connected to a
lubricant supply or integrated into a lubricant-carrying
system.
[0004] In order to avoid the aforementioned problem, dry-running
vacuum pumps are known in the prior art. DE 10 2015 010 846 A1 by
the same applicant describes an orbiter vacuum pump, of which the
design of the pump assembly is similar to the design of the pump
assembly of the present invention.
[0005] Dry-running vacuum pumps are generally lubricated by means
of a solid lubricant, such as in particular by means of graphite.
The solid lubricant graphite requires water or moisture for
establishing a low-friction layer between a moving and a static
pump part. The paucity of water in friction pairings in the vacuum
leads to an increase in the coefficient of friction. As the
inventors have established, the coefficient of friction of graphite
increases in the vacuum of a dry-running vacuum pump. The inventors
know that graphite, by reason of the behavior of the coefficient of
friction, is not suitable in the desired manner as a solid
lubricant for the application of a dry-running vacuum pump.
[0006] Therefore, the object of the invention is that of providing
an alternative solution for a dry-running orbiter vacuum pump
which, during vacuum operation, ensures a low loss of power from
friction.
[0007] This object is achieved by means of an orbiter vacuum pump
having the features of the main claim with respect to the present
invention. The dry-running orbiter vacuum pump in accordance with
the invention is characterized in particular in that at at least
one of a radial air gap and an axial air gap formed in a
cylindrical pump chamber between an orbiter eccentric piston and a
pump housing at least one sliding surface is arranged in a manner
exposed to the air gap; wherein the at least one sliding surface
comprises a microstructure including cavities for decreasing an
exposed surface of the at least one sliding surface.
[0008] The present invention provides for the first time a
microstructure on a sliding surface at an air gap or between a
moving and a static pump component in a dry-running pump for
gaseous media.
[0009] In particular, the invention provides for the first time a
sliding surface having a microstructure on an orbiter eccentric
piston and/or a pump chamber wall of the pump housing of a
dry-running orbiter vacuum pump.
[0010] In its most general form, the invention is based upon two
aspects of decreasing a surface of the sliding surface and of
producing an aerodynamic lubricating film in the air gap.
[0011] On the one hand, a friction-effective contact surface of the
sliding surface is decreased by means of the cavities of the
microstructure. The friction-effective contact surface of the
sliding surface always contributes to friction resistance whenever
friction contact occurs. Such friction contact occurs e.g. at the
axial air gap by reason of a floating bearing arrangement of the
orbiter eccentric piston in the pump chamber.
[0012] On the other hand, an aerodynamic lubricating film is
produced by means of the cavities of the microstructure, as
explained hereinafter. Such an aerodynamic lubricating film is
produced in the air gap if suitable pressure ratios are present.
These pressure ratios occur in particular at the radial air gap by
reason of the displacement procedures of the orbiter eccentric
piston. The radial air gap acts as a gap seal for separating the
pump chamber into a negative pressure region and a pressure region
on either side of the orbiter eccentric piston. The pressure
difference gives rise to a leakage in the form of an airflow
through the sealing gap or the corresponding air gap between the
orbiter eccentric piston and the opposite chamber wall.
[0013] Each cavity of the microstructure produces a small turbulent
swirl of the leakage airflow. Each small turbulent swirl bound
locally over the cavity produces an effect equivalent to a small
static air cushion bound locally over the cavity. Therefore, in
comparison with a laminar flow of an airflow between two smooth
surfaces, the sliding surface in accordance with the invention
produces an aerodynamic lubricating film consisting of small
turbulent air swirls which act in the same air gap in a manner
equivalent to a sum of small static air cushions. A forcing-apart
effect in terms of an air cushion or a friction-reducing effect in
terms of the aerodynamic lubricating film consisting of locally
bound turbulent swirls can be set on the basis of a number and
surface distribution of the cavities in the microstructure.
[0014] The aerodynamic lubricating film which is provided in
accordance with the invention and is produced by means of the
microstructure of the sliding surface in accordance with the
invention has several advantages.
[0015] The static pressure in the aerodynamic lubricating film
ensures that, comparable to an air cushion, direct axial surface
contact between end faces of the orbiter eccentric piston and the
chamber wall are largely suppressed. As a result, very low wear
occurs, thus achieving a long service life without any
deterioration in the sealing effect of the corresponding air gap in
terms of a gap seal.
[0016] Likewise, by reason of the lack of direct surface contact at
the aerodynamic lubricating film, very low coefficients of friction
are achieved which contribute to high energy efficiency of the
orbiter vacuum pump.
[0017] Furthermore, the static pressure in the aerodynamic
lubricating film constitutes a sealing-effective, separate pressure
zone between an intake pressure and an outlet pressure of the
orbiter vacuum pump. The locally bound turbulences over the
cavities of the microstructure produce alternating, discrete zones
of different pressures. Discrete zones of different pressures
constitute in principle a barrier against the passage of a flow in
a sealing gap or the corresponding air gap in the pump chamber.
This principle is known e.g. from seals having grooves or chambers
for providing a plurality of different pressure zones between two
sealing sides. The aerodynamic lubricating film which is provided
in accordance with the invention and is produced by means of the
microstructure thus permanently achieves a sealing effect between a
suction side and an outlet side of the orbiter vacuum pump which is
better than in the case of a gap seal which is formed at the same
air gap with the aid of smooth surfaces.
[0018] In summary, the aerodynamic lubricating film produced by
means of the sliding surface in accordance with the invention, in
avoiding direct friction contact, reduces static friction and
sliding friction between the orbiter eccentric piston and the pump
chamber, thus improving energy efficiency and wear resistance to
the benefit of the service life and operating reliability of the
orbiter vacuum pump. Moreover, the aerodynamic lubricating film
produced by the sliding surface in accordance with the invention
provides an improved sealing effect of the corresponding air gap
between a negative pressure region and a pressure region in the
pump chamber, whereby volumetric efficiency of the orbiter vacuum
pump is improved.
[0019] Advantageous developments of the invention are provided in
the dependent claims.
[0020] According to one aspect of the invention, the cavities of
the microstructure can have a closed contour towards the surface of
the at least one sliding surface. In comparison with a surface
roughness, the topology of which includes any shapes of cavities
having undefined contours, the closed contour of the cavities
ensures a defined turbulent swirl on the surface and the local
binding thereof to the closed contour, thus permitting targeted
formation of the aerodynamic lubricating film in the air gap.
[0021] According to one aspect of the invention, the cavities of
the microstructure can have a dimension of 10 to 100 .mu.m in a
depth direction to the surrounding surface of the at least one
sliding surface. Within the stated range, an effectiveness of the
cavities for producing turbulent swirls under the
application-specific operating conditions and dimensions in the air
gap of the orbiter vacuum pump is achieved.
[0022] According to one aspect of the invention, the cavities of
the microstructure can have a dimension of 10 to 1000 .mu.m in an
extension direction of a contour to the surrounding surface of the
at least one sliding surface. Even in this range, an effectiveness
of the cavities for producing turbulent swirls under the
application-specific operating conditions and dimensions in the air
gap of the orbiter vacuum pump is achieved.
[0023] According to one aspect of the invention, the cavities of
the microstructure can have the shape of a spherical cap, of an
ellipsoid spherical cap, of an elongated hole or of a groove. In
comparison with the shape of a spherical cap, the remaining shapes
listed permit orientation and shape-optimization of the
microstructure relating to the rotational direction or flow
direction in the air gap.
[0024] According to one aspect of the invention, the microstructure
of the at least one sliding surface can be produced at the
corresponding surface of the pump housing or of the orbiter
eccentric piston by means of laser-assisted melting of the
material. This technique ensures particularly rapid and precise
surface machining of the corresponding pump components.
[0025] According to one aspect of the invention, a material, on
which the microstructure of the at least one sliding surface is
produced, can be provided as a surface insert that is inserted into
a component body of the pump housing or of the orbiter eccentric
piston. This configuration means that, for a near-surface component
region of the sliding surface, a harder or other optimized
material, such as e.g. steel, can be selected, whereas, for the
remaining component body of the piston or of the housing, a lighter
and injection-moldable or other functionally optimized material,
such as e.g. a synthetic material or aluminium, can be used.
[0026] According to one aspect of the invention, the microstructure
of the at least one sliding surface can be produced on a metal
material provided by the pump housing or by the orbiter eccentric
piston. Different metal alloys provide preferred material
properties with regard to hardness, surface quality and the
machining capability thereof for producing the microstructure, in
particular by means of a laser.
[0027] According to one aspect of the invention, the metal
material, on which the microstructure of the at least one sliding
surface is produced, can be surface hardened by means of hard
anodizing. As a result, the wear resistance of the microstructure
and thus the longevity of the advantageous effect can be improved
by reason of the greater hardness of the material.
[0028] According to one aspect of the invention, the metal
material, on which the microstructure of the at least one sliding
surface is produced, can be provided as a sintered layer sintered
on a material of the pump housing or of the orbiter eccentric
piston. As a result, an alternative embodiment is proposed which,
in turn, renders it possible to select a harder metal material for
the sliding surface, while another optimized material can be used
for the remaining component body.
[0029] According to one aspect of the invention, the at least one
sliding surface can be additionally also arranged at at least one
surface of the blocking slide; wherein the at least one sliding
surface at the blocking slide also comprises the microstructure
including cavities for decreasing an exposed surface of the at
least one sliding surface. This embodiment ensures that it is
possible to utilize the advantageous effect of the inventive
sliding surface with the microstructure likewise in relation to a
sliding movement and sealing arrangement between the blocking slide
and the guide slot.
[0030] The invention will be explained in greater detail
hereinafter with reference to different embodiments of the
invention and the accompanying drawing. In the drawing:
[0031] FIG. 1 shows a cross-section of the pump chamber of an
orbiter vacuum pump according to one embodiment of the
invention;
[0032] FIG. 2 shows an axial cross-section of the orbiter vacuum
pump according to one embodiment in FIG. 1; and
[0033] FIG. 3 shows an enlarged section Z of the orbiter vacuum
pump according to one embodiment in FIG. 2.
[0034] As shown in FIG. 1, the orbiter vacuum pump according to one
embodiment of the invention is formed from a pump housing 1 which
comprises a pump chamber 2 with a cylindrical chamber wall. In the
pump chamber 2, an orbiter eccentric piston 3 performs a circular
movement, wherein a circumferential sliding contact of the orbiter
eccentric piston 3 with the cylindrical chamber wall is maintained.
Arranged in the orbiter eccentric piston 3 is a guide slot 4 in
which a blocking slide 5 is slidably received. The blocking slide 5
extends through the pump chamber 2 into the orbiter eccentric
piston 3 and is pivotably mounted at a free end. For this purpose,
a pivot bearing 14 is arranged in the chamber wall between an inlet
opening 6 and an outlet opening 7. The pump inlet has a nozzle for
connecting a vacuum hose.
[0035] In dependence upon the position of the orbiter eccentric
piston 3 in the circular movement in the pump chamber 2, a portion
of the blocking slide 5 located opposite the pivotably mounted end
slides in and out in the guide slot 4. As a result, the pump
chamber 2 is divided, either side of the blocking slide 5, into two
volumes, of which one communicates with the inlet opening 6 and one
communicates with the outlet opening 7. The volumes on each side of
the blocking slide 5 vary with the circumferential sliding contact
between the orbiter eccentric piston 3 and the cylindrical chamber
wall in equal proportions oppositely to one another such that a
cyclical displacement procedure which is explained hereinafter is
completed.
[0036] The illustration in FIG. 1 shows a position of the orbiter
eccentric piston 3 approximately halfway prior to a top dead
center, in which the increasing volume of the pump chamber 2 which
communicates with the inlet 6 and through which a gas is sucked in
reaches an almost maximum volume. After passing over the top dead
center, i.e. after the orbiter eccentric piston 3 has passed over
the sliding bearing 14 and the inlet opening 6, during the next
revolution in the clockwise direction the previously sucked-in gas
is pushed out through the outlet 7 by reason of a decreasing volume
on a leading side of the circumferential sliding contact between
the orbiter eccentric piston 3 and the cylindrical chamber wall,
whereas at the same time and to the same extent new gas is then
sucked through the inlet 6 into the pump chamber 2 by reason of an
increasing volume on a trailing side of the circumferential sliding
contact.
[0037] As shown in FIG. 2, a shaft 8 is arranged in the pump
housing 1 in such a manner as to be rotatably mounted by means of a
shaft bearing. The shaft 8 is driven by means of an electric motor
9. An eccentric disk 12 with an eccentrically arranged crankpin 13
is fixed on the shaft 8. The crankpin 13 engages into the center
point of the orbiter eccentric piston 3. During a rotation of the
shaft 8, the eccentric disk 12 performs the circular movement of
the orbiter eccentric piston 3 in the pump chamber 2 via the
crankpin 13. The orbiter eccentric piston 3 is designed in a
cylindrical manner in the form of a piston drum. Preferably, the
orbiter eccentric piston 3 is manufactured as a molded part by
means of injection-molding from a synthetic material, in particular
a fiber-reinforced synthetic material.
[0038] The outlet opening 7 is provided by means of an axially
oriented bore which issues into the pump chamber 2. It forms, in
conjunction with a pressure valve 17, an outlet to the environment.
The pressure valve 17 is provided by means of a bent sheet-metal
part which covers a rear side of the outlet opening 7 and is urged
back by means of a delivery pressure of a gas exiting the pump
chamber 2. One side of the pump housing 1, on which the electric
motor 9 is received, is closed off by means of a motor cover 19.
Furthermore, electronics for controlling an electric drive power
are arranged in the motor cover 19.
[0039] FIG. 3 shows an enlarged section Z of FIG. 2 which relates
to a region of the sliding contact between the orbiter eccentric
piston 3 and the cylindrical chamber wall of the pump housing 1 in
the pump chamber 2. At the apex of the sliding contact, there is
generally a small radial air gap R which for illustrative purposes
is shown in an exaggerated manner. Likewise, there is an axial air
gap A between the orbiter eccentric piston 3 and an end-face
chamber wall of the pump housing 1. On a side illustrated on the
left, the end-face chamber wall of the pump housing 1 is formed by
means of a pump lid 11.
[0040] On the one hand, the radial air gap R and the axial air gap
A in the pump chamber 2 are necessary in order to ensure a
low-friction circular movement of the orbiter eccentric piston 3 in
the pump chamber 2 within the scope of manufacturing and fitting
tolerances. Furthermore, the radial air gap R and the axial air gap
A ensure that the orbiter eccentric piston 3 cannot become jammed
during the circular movement even by small, particulate impurities,
which can be sucked in with a gas flow. The dimension of the radial
air gap R and of the axial air gap A is preferably several 10
.mu.m, e.g. 50 .mu.m for the radial air gap R and either side of
the orbiter eccentric piston 3 in each case 30 .mu.m for the axial
air gap A. The orbiter eccentric piston 3 is mounted in a floating
manner in the axial direction, i.e. is received in a freely movable
manner on the crankpin 13, such that an equilibrium of flows and
pressure zones in the axial air gaps A on either side means that an
axial position of the orbiter eccentric piston 3 is achieved in an
automatically displaceable manner.
[0041] Nevertheless, axial movements, external effects such as
vibrations or accelerations in a system environment, moisture,
impurities, temperature fluctuations or otherwise caused material
stresses or material expansions bring about temporary or permanent
reductions in the contact-free gap dimension of the axial air gap A
or of the radial air gap R to a gap dimension of 0 .mu.m such that
there is contact between opposing surfaces. Therefore, between the
orbiter eccentric piston 3 and the chamber walls of the pump
housing 1 friction-effective sliding contacts also exist at certain
points or in a planar manner in the axial air gap A or in the
radial air gap R.
[0042] In various embodiments of the invention, orbiter vacuum
pumps are provided having different arrangements and configurations
of sliding surfaces which reduce disruption of the pump operation
or impairment of efficiency by friction-effective sliding contacts
in the axial air gap A or in the radial air gap R.
[0043] In the case of a first embodiment of the invention which is
shown in FIG. 3, a specific sliding surface 30, which is explained
hereinafter, is provided on the radial outer surface of the orbiter
eccentric piston 3. The sliding surface 30 comprises a
microstructure with cavities which is illustrated by checkered
hatching. The cavities are arranged in a regular pattern
distributed uniformly over the sliding surface 30. Furthermore, the
cavities comprise a closed contour towards the surface, i.e. each
cavity is separated with respect to an adjacent cavity in any
direction by means of an intermediate portion of the surface of the
sliding surface 30. As a result, the sliding surface 30 comprises a
decreased surface area in relation to friction contact in the
radial air gap R.
[0044] The cavities of the microstructure are produced at the
sliding surface by means of a laser, wherein material is partially
removed by the melting of material on the surface. The shape of the
cavities is selected in favor of a machining speed preferably
corresponding to a projected shape of the impinging laser beam or a
mask. Therefore, a contour of the cavities preferably has a simple
shape without angles, such as spherical cap or an elliptical
spherical cap. The cavities comprise a depth of 10 to 100 .mu.m and
a diameter of 10 to 1000 .mu.m in an extension direction of the
contour. In an exemplified embodiment, the microstructure of the
sliding surface 30 comprises round cavities having a depth of 20
.mu.m and a diameter of 100 .mu.m.
[0045] The material of the sliding surface 30 at which the
microstructure with the cavities is produced consists of a
hard-anodized metal alloy. More specifically, a metal layer is
applied on the body--designed as a piston drum--of the orbiter
eccentric piston 3 which is manufactured from a fiber-reinforced
synthetic material. The metal layer is sintered on the material of
the orbiter eccentric piston 3 in the form of a sintered metal
layer consisting of a sintered alloy. Moreover, the sintered metal
layer is subjected to a process of surface hardening by means of
hard anodizing.
[0046] In alternative variants of the first embodiment, a metal
layer for producing the sliding surface 30 as an annular or
cylindrical material insert is provided on the outer surface of the
orbiter eccentric piston 3, or the entire body of the orbiter
eccentric piston 3 consists of a corresponding metal, such as a
stainless steel.
[0047] In a not-illustrated, second embodiment of the invention, a
sliding surface 20 comprising a microstructure with cavities is
arranged on the cylindrical chamber wall of the pump housing 1
which is exposed to the radial air gap R. The microstructure of the
sliding surface 20 corresponds in all configurations of the
cavities to the previously explained microstructure of the sliding
surface 30 of the first embodiment. Likewise, a material selection
of a metal having a hard-anodized surface for the sliding surface
20 corresponds to the preferred material selection for the sliding
surface 30 of the first embodiment. However, in the second
embodiment, the material for the sliding surface 20 is provided
such that the entire body of the pump housing 1 is manufactured
from a corresponding metal.
[0048] In alternative variants of the second embodiment, only a
metal layer for producing the sliding surface 20 is provided on the
pump housing. The metal layer is provided as an annular or
cylindrical material insert consisting of a stainless steel on the
inner surface of the cylindrical chamber wall of the pump housing
1, or in the same region the metal layer is sintered on the
material of the pump housing 1 in the form of a sintered metal
layer consisting of a sintered alloy. In the case of these
variants, the body of the pump housing 1 can be manufactured from
another metal, such as an injection-moldable light metal alloy or
even from a synthetic material.
[0049] In a not-illustrated, third embodiment of the invention,
sliding surfaces 10 comprising a microstructure with cavities are
arranged on the end-face chamber walls of the pump housing 1 and
the pump cover 11 which are exposed to the axial air gap A. The
microstructure of the sliding surfaces 10 corresponds in all
configurations of the cavities to the previously explained
microstructure of the sliding surface 30 of the first embodiment.
Likewise, a material selection of a metal having a hard-anodized
surface for the sliding surfaces 10 corresponds to the preferred
material selection for the sliding surface 30 of the first
embodiment. However, in the third embodiment, the material for the
sliding surfaces 10 is provided such that the pump cover 11 and the
entire body of the pump housing 1 are manufactured from a
corresponding metal.
[0050] In alternative variants of the third embodiment, only a
metal layer for producing the sliding surfaces 10 is provided on
the pump housing 1 and the pump cover 11. The metal layer is
provided as a planar material insert in the form of a steel sheet
on the inner surface of the pump cover 11 and the end-face chamber
wall of the pump housing 1, or in the same regions the metal layer
is sintered on the material of the pump cover 11 and the material
of the pump housing 1 in the form of a sintered metal layer
consisting of a sintered alloy. In the case of these variants, the
body of the pump cover 11 and the body of the pump housing 1 can be
manufactured from another metal, such as an injection-moldable
light metal alloy or even from a synthetic material.
[0051] In a fourth embodiment of the invention, sliding surfaces
comprising a microstructure with cavities are arranged additionally
on the surfaces of the blocking slide 5 which are exposed to the
guide slot 4 of the orbiter eccentric piston 3. The microstructure
of these sliding surfaces likewise corresponds in all
configurations of the cavities to the previously explained
microstructure of the sliding surface 30 of the first embodiment.
Likewise, a material selection of a metal having a hard-anodized
surface for these sliding surfaces corresponds to the preferred
material selection for the sliding surface 30 of the first
embodiment. In this case, the material for these sliding surfaces
is provided such that the body of the blocking slide 5 is
manufactured from a corresponding metal, such as a stainless
steel.
[0052] In a further alternative embodiment of the invention,
sliding surfaces comprising a microstructure with cavities are
arranged additionally on axial surfaces of the orbiter eccentric
piston 3 which are exposed to the axial air gap A. The
microstructure of such sliding surfaces likewise corresponds in all
configurations of the cavities to the previously explained
microstructure of the sliding surface 30 of the first embodiment.
Likewise, a material selection of a metal having a hard-anodized
surface for such sliding surfaces corresponds to the preferred
material selection for the sliding surface 30 of the first
embodiment.
[0053] It should be noted that the various embodiments and their
alternative variants can be combined with one another and in
particular can be added to one another in order to provide an
orbiter vacuum pump in accordance with the invention having the
previously described advantages.
LIST OF REFERENCE NUMERALS
[0054] 1 pump housing [0055] 2 pump chamber [0056] 3 orbiter
eccentric piston [0057] 4 guide slot [0058] 5 blocking slide [0059]
6 inlet/inlet opening [0060] 7 outlet/outlet opening [0061] 8 shaft
[0062] 9 electric motor [0063] 10 axial sliding surfaces of the
pump housing/of the pump cover [0064] 11 pump cover [0065] 12
eccentric disk [0066] 13 crankpin [0067] 14 pivot bearing [0068] 17
pressure valve [0069] 19 motor cover [0070] 20 radial sliding
surface of the pump housing [0071] 30 radial sliding surface of the
orbiter eccentric piston [0072] A axial air gap [0073] R radial air
gap [0074] Z enlarged section
* * * * *