SINGLE-BLADE VACUUM PUMP

POMPE A VIDE A UNE SEULE AILETTE

English Abstract

The invention relates to a single-winged vacuum pump provided with a pot-
shaped housing (12), a rotor (18) which is rotationally and eccentrically
mounted in the housing, a wing (20) which is displacably mounted in the rotor
and orthogonal on the rotational axis and a work chamber (22) which receives
the wing (20) and which comprises an internal peripheral surface (30) whereon
both of the sealing edges (68), which are arranged opposite to each other of
the wing, are arranged. The wing (20) subdivides the work chamber into a
suction chamber (30) and a pressure chamber and the end (28) of the wing,
which is oriented towards the internal peripheral surface (30), comprises a
flattened section (66) on the side oriented towards the pressure chamber (26).

French Abstract

L'invention concerne une pompe à vide à une ailette, qui comprend un carter (12) en forme de creuset, un rotor (18) monté de manière rotative et excentrique dans le carter, une ailette (20) logée mobile dans le rotor orthogonalement à l'axe de rotation, ainsi qu'un espace de travail (22) recevant l'ailette (20) et muni d'une surface périphérique intérieure (30) contre laquelle s'appuient les deux arêtes d'étanchéité (68) opposées l'une à l'autre de l'ailette. Selon l'invention, l'ailette (20) subdivise l'espace de travail en une chambre d'aspiration (24) et en une chambre de pression et l'extrémité (28), dirigée vers la surface périphérique intérieure (30), de l'ailette présente un segment aplati (66) sur sa face orientée vers la chambre de pression (26).

Claims

Claims
What is claimed is:
1. A single-blade vacuum pump comprising a pot-shaped
housing (12), a rotor (18) which is rotationally and
eccentrically mounted in the housing, a blade (20)
which is displaceably mounted in the rotor and
orthogonal on the rotational axis, and an expansion
chamber (22) which receives the blade (20) and
comprises an inner peripheral surface (30) whereon
abut the two sealing edges (68) of the blade, which
are arranged opposite to one other, wherein the blade
(20) subdivides the expansion chamber (22) into an
inlet chamber (30) and a pressure chamber (26),
wherein the end (28) of the blade (20) facing the
inner peripheral surface (30) comprises a flattened
section (66) and wherein the surfaces bordering onto
section (66) are partially cylindrical.
2. A single-blade vacuum pump as defined in claim 1,
wherein the flattened section (66) is even.
3. A single-blade vacuum pump as defined in claim 1 or
claim 2, wherein the section (66) comprises an angle
varying by 0° towards the longitudinal surface of the
blade (20).
4. A single-blade vacuum pump as defined in any one of
claims 1 to 3, characterized in that the blade (20)
eccentrically abuts on the inner peripheral surface
(30).

11
5. A single-blade vacuum pump as defined in any one of
claim 1 to 4, wherein the line of contacts (68) of the
blade (20) comprises a distance (A) towards the center
level (70) of the blade (20).
6. A single-blade vacuum pump as defined in claim 1,
wherein the surfaces continuously go over to the
section (66).
7. A single-blade vacuum pump as defined in claim 1,
wherein the surfaces and the section (66) at the
transition points comprise similar tangents.
8. A single-blade vacuum pump as defined in any one of
claims 1 to 7, wherein the blade (20) comprises a body
(32) and two terminal top parts (34).
9. A single-blade vacuum pump as defined in claim 8,
wherein the body of the blade (32) at its ends (32)
accommodating the top parts (34) comprises a slot
(40), which runs orthogonally towards the longitudinal
broadside (44) of the body of the blade (32).
10. A single-blade vacuum pump as defined in claim 8 or 9,
wherein the top part (34) comprises a U-shaped cross-
section created by two parallel limbs (48).
11. A single-blade vacuum pump as defined in claim 10,
wherein the limbs (48) flank a fixed link (50).
12. A single-blade vacuum pump as defined in claims 9 and
11, wherein with the mounted blade (20) the fixed link
(50) engages in a slot (40).

12
13. A single-blade vacuum pump as defined in any one of
claims 8 to 12, wherein the top part (34) turned by
180° can be plugged on the body of the blade (32).

Description

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
Title: Single-Blade Vacuum Pump
Description
The invention relates to a single-blade vacuum pump provided with
a pot-shaped housing, a rotor which is rotationally and
eccentrically mounted in the housing, a blade which is
displacably mounted in the rotor and orthogonal on the rotational
axis, and a expansion chamber which receives the blade and
comprises an inner peripheral surface whereon abut the two
sealing edges of the blade, which are arranged opposite to one
other, wherein the blade subdivides the expansion chamber into an
inlet chamber and a pressure chamber.
Vacuum pumps with this type of structure are known from (DE 100
46 697 A1). As a rule, they serve to provide vacuum users, for
example, in motor vehicles, with vacuum in that the rotor is
caused to rotate, and air is evacuated from the inlet chamber
from an vacuum line via the intake arm. The expansion chamber of
this vane pump is designed in such a way that the blade with its
two ends, which are located opposite one another, moves along the
inner peripheral surface. Further, the blade separates the inlet
chamber, which is connected to the intake connection from the
pressure chamber, which is connected to the pressure connection.
In order to achieve a high degree of efficiency, the blade must
abut permanently on the inner peripheral surface, otherwise the
inlet chamber will be ventilated.

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
2
A known solution proposes that the blade be structured in two
parts and that a spring be inserted between the two blade
components, which forces the two blade components towards the
outside in the direction of the peripheral surface. This ensures
that the sealing edge of the blade permanently abuts on the inner
peripheral surface. However, it is considered to be a
disadvantage that, because of the contact pressure, the blade is
subjected to considerable wear, as a result of which not only the
efficiency of said blade diminishes, but also maintenance
intervals are reduced as well.
From the DE 43 32 540 Al, a vane pump is known in which several
blades are arranged eccentrically in the rotor. At the point and
the base of said blade, said blades are pressurized with the
pressure prevailing in the pressure chamber. From DE-PS 364 107,
a lubricating device for fast running rotors is known in which
the blade distributing the lubricant film is chamfered.
It is the object of the present invention to provide a single
blade vacuum pump with improved efficiency.
In view of the foregoing, a single-blade vacuum pump of the
aforesaid type is used to solve the problem in accordance with
the invention in that the ends of the blade facing the inner
peripheral surface comprise a flattened section facing the
compression chamber.
Usually the ends of the blade are rounded cylindrically and via a
central line of contact or surface line of the cylinder abut on
the inner peripheral surface of the expansion chamber. With

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
3
the single-blade vacuum pump according to the invention, the end
of the blade is partially flattened on the pressure side as a
result of which the blade is able to change effective pressure
forces in their direction. Due to the flattened section, the
radial component of the pressure force is increased, which
counteracts the centrifugal force of the blade. The centrifugal
force of the blade, which presses the blade against the
peripheral surface of the expansion chamber therefore is reduced
by the compression force counteracting said centrifugal force
from the pressure chamber. The blade, therefore, is pressed with
less force against the peripheral surface.
With the preferred embodiment, the flattened section is easily
configured. This type of configuration of the blade end can be
produced with relative ease because the flattened section, for
example, can be attached and/or produced by means of a milling
process.
In an improvement, the section comprises an angle to the
longitudinal surface, which varies by 0 . Furthermore,
eccentrically the blade abuts on the inner peripheral surface.
The line of contact also has a distance to the center plane of
the blade, as a result of which the improvement is achieved that
the flattened section can be larger. As a result, the tangential
component of the compression force can be reduced even further.
With a preferred embodiment, it is provided that the section
bordering on and/or the surfaces bordering on the section are
partially cylindrical. This offers the advantage that the line

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
4
of contact can move relatively easily along the surface of the
point of the blade. Since the contact angle of the blade changes
permanently during a complete rotation of the rotor, the line of
contact of the point of the blade moves negligibly in which the
cylindrical design of the point of the blade ensure even wear.
A harmonious course and, therefore, a simple production of the
point of the blade is achieved in that the surfaces at the point
of the blade continuously change into a flattened section.
Further, the surfaces and the section at the transfer points may
comprise similar tangents. The processing tools are able to
produce the point of the blade in one operating cycle and/or with
an injection-molded point, the injection mold can be produced
simply and at a low cost.
Preferably, the blade comprises a body and two terminal top
parts. At said top parts, the flattened section is attached and
said top parts abut on the inner peripheral surface of the
expansion chamber. This has the major advantage that worn blades
can be maintained by replacement of the top parts, wherein the
top parts preferably are made of synthetic material, whereas the
body of the blade, for example, is made of metal. Further, the
body of the blade is a die-cast or injection-molded element, and
the top parts are injection-molded.
For the purpose of attaching the top parts, the body of the blade
comprises at its top parts the ends accommodating the top parts
in a slot, which runs orthogonally towards the long side of the
body of the blade. The top part comprises one of two

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
parallel U-shaped or C-shaped cross-sections. Consequently, the
top parts can be plugged in at various ends of the body of the
blade, and are movable only in the direction of the longitudinal
axis of the blade. As a result, owing to their centrifugal
force, such top parts can abut on the inner peripheral surface of
the expansion chamber and seal the inlet chamber opposite the
pressure chamber.
With one embodiment, the limbs flank a fixed link, whereby the
limbs themselves at their free ends are formed as a semi-circle,
and engage in a corresponding semi-circular recess at the ends of
the body of the blades. Both the fixed link and the recess for
the limbs prevent the top parts from effecting undefined motions
during the operation of the pump. In particular, this prevents
shaking and rattling, and furthermore the development of noises
is suppressed. In an improvement, the top parts are placed under
minor initial stress force at the ends of the body of the blade.
Another characteristic feature is that when turning the top part
by 1800, said top part can be rotated on the body of the blade.
This means that the ends of the body of the blade and the seat
are so designed that they allow the top parts to be rotated.
Other advantages, characteristics, and details of the invention
are specified in the subordinate claims and in the following
description in which, by referring to the drawing, a preferred
embodiment is described in detail. Further, the characteristic
elements represented in the drawing and mentioned in the

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
6
description and in the claims can be fundamental to the invention
individually or in any combination.
Of the drawing:
Figure 1 shows an exploded view of the vacuum pump;
Figure 2 shows a perspective view of a single-blade vacuum pump
and blade;
Figure 3 shows a perspective presentation of the body of the
blade;
Figure 4 shows a perspective view of the top part; and
Figure 5 shows a horizontal projection of one end of the blade,
indicating the distribution of compression pressure.
Figure 1 shows the vacuum pump with the overall reference symbol
wherein the housing 12 is represented without cover. The
housing 12 has a suction connection 14, which ends in an interior
16. This interior 16 contains a rotor with the overall
designation 18, wherein a blade 20 is rotatably mounted
orthogonally to the axis of rotation 21.
As is evident from Figure 2, the blade 20 subdivides the
expansion chamber 22, which is formed by the interior 18, into an
inlet chamber 24 and a pressure chamber 26. Further, the blade
with its two ends 28 abuts on one of the inner peripheral
surfaces 30 surrounding the expansion chamber 22.

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
7
As is shown in Figure 1, the blade 20 is formed by a body 32 and
two top parts 34. Figure 3 shows the body of the blade 32,
wherein Figure 4 shows one of the top parts 34. In the
embodiment, the body of the blade 32 is made of metal, and is a
die-cast part, which however also may be injection-molded. For
tribological reasons, the top part 34 is made of synthetic
material and injection-molded. For the purpose of weight
reduction and in order to reduce moments of inertia, the body of
the blade 32 is provided with cavities 36, which are either
continuous or are formed as blind holes. At its two ends 38, the
body of the blade 32 respectively is provided with a slot 40,
which extends not only in the direction of the longitudinal axis
42 of the blade 20, but also orthogonally towards the broadside
surface 44. The longitudinal axis 42 of the blade 20 is located
between the two broadside surfaces 44, and the line of contact 68
is located between the longitudinal center plane 70 and the
broadside surface 44 facing the inlet chamber 42.
Furthermore, the two broadside surfaces 44 in the area of the
ends 38 are essentially provided with semi-circular recesses 46
in which the limbs 48 (see Figure 4) of the top part 34 can be
plugged. The two limbs 48 flank a fixed link 50, which also
extends in the direction of the longitudinal axis 42 of the blade
20 and the form of a slot 40. Both the slot 40 with the fixed
link 50 and the recess 46 prevent that the top part 34 from being
displaced in the direction of the axis 52. The limb 48, which
encloses the end 38, prevents that the top part 34 from abruptly
giving way in the direction of the axis 54. This means that the
top part 34 is merely fixed in the direction of

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
8
the longitudinal axis 42, which is movable at the body of the
blade 32.
Figure 5 shows a horizontal projection of the body of the blade
32 with mounted top part 34. Further, the top part 34 touches
the inner peripheral surface 30, so that the inlet chamber 24 is
located below and the pressure chamber 26 above the blade 20.
The blade 20 rotates in the direction of the arrow 56 and at its
rear, facing in the inlet chamber 24, and an angle other than 900
goes over to the broadside surface 44 of the blade 20.
If the blade 20 comprises a rounded end 28, the axial compression
force 58, which, for example, is created by the pressure in the
pressure chamber 26, would have an effect on the end 28. Said
compression force 58 acts against the centrifugal force of the
blade 20, as indicated with the arrow 64.
As is shown in Figures 4 and 5, the top part 34 has a flattened
section 66 upon which acts the compression force 60. Said
compression force 60 is composed of the compression force 58 and
an additional compression force 62, which is created because the
line of contact 68 comprises a distance A to the center plane 70
of the blade 20. Since the compression force 60 actually
attacking the blade 20 is greater than the compression force 58
with a conventional blade on account of the shift of the line of
contact 68, and furthermore, the forces 74 created by the vacuum
in the inlet chamber 24 are smaller then with a conventional
blade, the contact pressure at the line of contact 68 is
considerably reduced, which reduces wear.

CA 02575778 2007-02-01
WO 2006/005381 PCT/EP2005/004210
9
Furthermore, it is evident that the line of contact 38 is located
on a partial cylindrically shaped section 72 of the top part 34.
The partial cylindrically shaped section 72, maintaining the same
tension, continues to the level section 66. This has the
advantage that the lubricant on the pressure side of the blade 20
is distributed evenly over the section 66 and the section 72, so
that the line of touch 68 is lubricated across its entire length.

Representative Drawing