DE102008060875A1 - Toothed ring or wheel pump for conveying fluid i.e. oil, has direct current motor whose polar pairs are aligned in radial manner, and drive-, motor- and pump shafts supported in stator on one side, and in housing of pump in another side - Google Patents

Abstract

The pump (1) has pump rotors (21) connected with a motor shaft, (22), a pump shaft (23) and a common drive shaft (3) of a brushless direct current motor (2), whose permanent magnets (18) are formed with poles arranged in pairs. A housing (8), a pump cover (9) and a pump base (13) of a pump, and a stator (16) of the direct current motor are connected with each other in a rigid manner. The common drive shaft, the motor shaft and the pump shaft are supported in the stator, on one side, and in the housing of the pump, in another side. The polar pairs of the motor are aligned in a radial manner. The brushless direct current motor is designed as an external rotor.

Description

The The invention relates to a driven by a DC motor Gear pump for conveying fluids with a pump rotor, the rotatably connected to a drive shaft of the DC motor is.

One Aggregate consisting of a reservoir, a pump under oil and components for supplying the electric motor with hydraulic Energy, is called a power pack.

From the EP 1 255 928 B1 For example, such a gear pump for conveying fluids having a driven pump rotor with external toothing is known, which engages in the internal toothing of a pump ring. The pump rotor is rotatably connected to the drive shaft of a brushless DC motor.

From the DE 43 25 502 C2 a positive displacement driven by an electric motor is known, in which the angular position of the grooves of an electric motor for driving a gear pump with respect to the teeth of the displacement of the pump is oriented such that torque oscillations of the armature of the motor counteract the pulsations of the gear pump and thus compensate, whereby the Noise development of the gear pump is reduced.

to Supply of hydraulic drives with drive energy required one hydraulic pumps. Here are preferred positive displacement pumps used, which consist of at least one chamber which opens periodically and thereby pressure fluid, hereinafter called fluid, sucked from a reservoir. At the end of this suction phase, the chamber closed against the reservoir and the fluid is at a high Compressed pressure.

this Process is called reversing for compression. In the following Phase, the chamber is connected to the high pressure side. The chamber volume is reduced and the fluid against the hydraulic resistance pushed out on the consumer side. This requires a performance proportional to the pressure on the consumer side and the rate of change the chamber volume is. In the second Umsteuerphase then the Chamber separated from the high pressure side and the remaining volume in the chamber decompressed. To make these processes more continuous to design, multiply the number of displacement elements, the number of which is always referred to below as m. The m displacement elements are arranged eccentrically about a rotation axis and with a shaft driven.

The reversing can take place in various ways: pressure-controlled;
in the suction and pressure area are non-return valves, which allow a volume flow only from the reservoir to the pump and from the pump to the consumer,
force pilot;
the shaft additionally drives a structural element (control mirror), which creates connection openings between the displacement chambers and the suction and pressure side, or
geometry controlled;
the displacement chamber rotates itself and is guided past correspondingly designed openings.

When The drive of this pump are various rotary energy converters such as internal combustion engines, gas or water turbines or electric motors conceivable. If you focus on electric motors, so come here various types of electric motors used. The housing of a positive displacement pump is mechanical firmly connected to the housing / stator of an electric motor. The engine is attached to the lid of the oil reservoir and At least the pump is completely immersed in the fluid. The fluid is directly through an opening in the pump housing sucked out of the reservoir.

The Hydraulic consumers are via a pipeline or a hose connected to the pump.

at electrically conductive fluids, in heavily contaminated fluids at highly viscous or poorly lubricating media must Motor bearing and the rotor of the motor are separated from the medium, you use a shaft seal.

Usually the pump and the motor are two structurally separate machine elements. Both the rotor of the pump and the rotor of the motor are disconnected stored from each other. When connecting the two elements must Misalignment and shaft offsets by accordingly designed couplings are compensated. However, too so-called slip-on pumps available, for example vane pump, where the pump rotor is plugged onto the shaft of the motor. The misalignment must then about adjustment, For example, rubber buffer, balanced in the pump housing become.

The known solutions have the following disadvantages: Noise:
The periodic alternating forces occurring during the rotation of the engine cause an elastic deformation of the structure, which manifests itself as noise emission;
Power losses:
Mechanical friction of the displacement elements and viscous friction in the fluid results in efficiency losses;
Leakage and wear:
The shaft seal and engine mounts are extremely sensitive to wear; Worn shaft bearings result in external leakage The above-mentioned disadvantages must be avoided by elaborate detailed designs in their effect.

The The object of the invention is a robust pump drive to create, which works very quietly.

The object is achieved by the following features of claim 1:
the rotor of the DC motor is formed of permanent magnets with poles arranged in n pairs,
at least one of the poles of the permanent magnet associated with the rotor of the DC motor is positioned relative to the teeth of the pump rotor such that system-related fluctuations in the torque of the gear pump are counteracted,
the housing of the gear pump and the stator of the DC motor are rigidly connected to each other,
the common drive shaft is mounted on one side in the stator of the DC motor and on the other side in the housing of the gear pump and the n pole pairs of the DC motor are radially aligned, wherein the brushless DC motor can be a BLDC motor.

It has proven to be advantageous if the gear pump has a gerotor pump with a housing, an internal pump rotor with gears and a pump ring surrounding the pump rotor and if the product of the number of rotor teeth m * and the number of toothed ring teeth m + 1 in a three-phase DC motor is equal to the pole change frequency 6 * n, where m * (m + 1) = 6 * n.

According to the invention the rotor of the brushless DC motor and the pump rotor the gear pump rigidly mounted on a shaft and in two shaft bearings be included.

a Especially quiet running results when the rotor of the DC motor is mounted with a shaft bearing in its center of gravity.

In Advantageously, the shaft bearings can be designed in this way be that the distance between the first and second shaft bearings is equal to the height of the rotor.

Conveniently, the shaft is formed thickened between the two shaft bearings.

One quiet running in the manner of a symmetrical top poses when the rotor is formed such that its diameter is almost equal to its height.

It has proven to be beneficial when the number of teeth m and the number n of the poles is integer, in particular the Polzahl is seven or twelve.

The Surface pressure and the wear of the shaft in the contact zone decrease when the shaft bearings needle roller bearings are.

According to the invention the poles against the control grooves be aligned so that the pulsation becomes minimal.

The Pressure swing forces on the shaft are minimal when the Rotor is arranged mirror-symmetrically.

In Advantageously, the three phases of the stator are against the suction port of the pump oriented that the torque of the DC motor when reversing becomes maximum.

According to the invention the rotor and the shaft bearings are flowed around by the fluid from the reservoir, wherein the shaft bearings are hydrodynamically lubricated plain bearings can.

It has proven to be advantageous when the assembly with screws is clamped on a flat surface, the assembly Clamped by soft seals on the front sides of the pump housing is and no metallic contacts between the assembly and pump housing take place because it does not transmit vibration and noise can.

In Advantageously, the gap between the pump housing and DC motor filled with fluid from the reservoir be.

Conveniently, the gear pump includes a gerotor pump, which is the pump housing the ring gear pump is designed in three parts and the second Shaft bearing between pump housing and stator provided is, the shaft is plugged into the pump rotor and the permanent magnet sintered together with the shaft.

According to the invention, the DC motor may be a so-called "external rotor" in which the stator is arranged with the coil windings inside and coaxial with the rotor with the permanent magnet surrounded.

It has proven to be advantageous if at least one of the radial aligned n poles of the permanent magnet against the m teeth the pump rotor is rotated such that the pulsation of the pump is minimized.

Conveniently, is the number m of the teeth of the pump rotor with the number n the poles of the armature are designed as alien.

According to the invention the DC motor to be assigned an electronics that the magnetic field the coils arranged in the stator influenced, wherein the magnetic field the coils are set to compensate for systemic variations in the Torque of the gear pump is counteracted.

In Advantageously, the phases of the stator against an intake port and / or an exhaust port the pump are oriented, and that the torque of the DC motor when reversing from decompression to compression is maximal.

It has proven to be advantageous when the DC motor and the pump are arranged in a housing when the shaft the DC motor at its two ends in lids of the housing is mounted and carries the armature and the pump rotor, and that the fluid has lubricating properties and the DC motor filled with fluid.

In Advantageously, the lids on soft seals be clamped on the front sides of the housing.

The Invention is described below with reference to the drawing Embodiments explained in more detail. Show it:

1 an inventive motor-pump assembly with a pump motor as external rotor and

2 a further motor-pump arrangement according to the invention (gear pump) with a pump motor as an internal rotor.

In the 1 a motor-pump assembly is shown, which consists of a reservoir, not shown, a pump under oil, in particular a gear pump or gear pump 1 with valve, and a brushless DC motor 2 , for example a BLDC motor. This drive motor of the gerotor pump 1 , the brushless DC motor 2 , For example, may be a so-called external rotor, in which a stator inside 16 with coil windings 15 is arranged coaxially by a rotor 6 with permanent magnets 18 is surrounded as an external rotor.

One with the rotor 6 rotatably connected motor shaft 22 and a pump shaft 23 form a common wave inserted into each other 3 the so-called power pack. The wave 3 is between two shaft bearings 4 and 5 thickened trained. With the pump shaft 23 is also rotatably a toothed pump rotor 21 connected in a pump housing 8th is arranged and by a pump ring 10 surrounded by internal teeth. The pump housing 8th is on the side to the DC motor 2 out from a pump cover 9 and on the other side of a pump floor 13 covered. The pump cover 9 is with a flange-like axial alignment for guiding the motor shaft 22 educated. An axial writing 12 serves as a stop and guide the pump shaft 23 opposite the pump bottom 13 ,

The stator 16 of the DC motor 2 is rigid over the flange axial alignment with the pump housing 8th the ring gear pump 1 connected.

The rotor 6 and the shaft bearings 4 and 5 can be flowed around by the fluid from the reservoir.

The first in the DC motor 2 arranged shaft bearings 4 , For example, a needle bearing, can be hydrodynamically lubricated and sits in the center of gravity of the DC motor 2 ,

The second shaft bearing 5 , For example, also a hydrodynamically lubricated needle bearing is in the pump bottom 13 arranged.

A gap 7 between DC motor 2 and gear pump 1 is provided as acoustic insulation with a soft seal, such as an insulating disc, so that no metallic contacts between the assembly and the pump housing 8th can take place. The gap 7 is further filled with fluid from the reservoir to the heat transfer between the pump housing 8th and the DC motor 2 to improve.

On the to the ring gear pump 1 Directed side is the DC motor 2 with a circuit board 11 for soldering the coil windings 15 and provided for their connection.

The stator 16 of the DC motor 2 consists of a claw pole motor of six half rings, of which two each to a stator ring 14 are summarized. In the open spaces between two half rings of the stator rings 14 are the coil windings 15 brought in.

A cylinder screw 17 axially fixes the motor shaft 22 with the rotor 6 , In the rotor 6 are on three circular rings the stator rings 14 opposite permanent magnets 18 arranged. Formed as rings iron yokes 19 of the rotor 6 enclosed the permanent magnets 18 , spacers 20 made of non-magnetic material are between the iron yokes 19 arranged.

In the 2 a further motor-pump assembly according to the invention is shown, which consists of a gear pump 30 with a pump motor 31 exists as an inner rotor and a housing 32 with a floor 33 and a bearing cap 34 having. In the case 32 are a stator 35 and a pump cover 36 to the pump motor 31 and a pump cover 37 arranged. Between the pump covers 36 and 37 is the pump rotor 38 and a pump ring 39 arranged. A common wave 40 is in the pump cover 36 and in the bearing cap 34 stored. On the wave 40 the rotor is sitting 41 the pump motor 31 , At the same time is the pump rotor 38 with the wave 40 firmly connected.

The electrical connection 42 of the stator 35 is with an electronic circuit 43 connected to the connector plug 44 is coupled.

The fluid is not shown suction between the pump rotor 38 and pump ring 39 sucked. There between the pump cover 36 and the pump motor 31 No seal is provided, the fluid can also be in the pump motor 31 , a so-called sub-oil engine, where it on the one hand for hydrostatic bearing of the shaft 40 but also serves to dissipate the heat energy and to dampen the noise. In a drain connection, also not shown, the compressed fluid from the gear pump 30 pressed to the consumer.

The inventive combination of a gerotor pump with a brushless DC motor whose rotor (three phases, n pairs of poles) is formed from permanent magnets, gives a particularly quiet and robust pump drive. The pump delivers a low-viscosity, lubricating fluid, such as oil. This module is installed as a so-called lower oil unit in a pump housing. The module is structured as follows:
the rotor of the pump and the rotor of the DC motor are rigidly connected to each other on a common shaft,
the housing of the gears and the stator of the pump are rigidly connected to each other,
the common wave is on one side in the stator of the DC motor,
stored on the other side in the housing of the gears and / or the n pole pairs of the DC motor are radially aligned.

The combination according to the invention is characterized by the following features:
the product of the number of rotor teeth m * and the number of toothed ring teeth m + 1 is equal to the pole change frequency 6 * n for a three-phase DC motor m * (m + 1) = 6 * n.

Of the Rotor of a brushless DC motor and the rotor the displacement pump are rigidly mounted on a shaft and recorded in two shaft bearings.

The Noise reduction and the associated pulsation achieved by causing events that cause sound emission, be synchronized with the speed. For this purpose, the one Position of the bearings and the design of the shaft suitable chosen, and on the other hand, by the number of poles of the rotor on the DC motor and the number of displacement chambers matches each other.

The Prevention of noise emissions is based on two principles: the excitation of the vibrations is made very narrow band. This will the excitation on a few frequencies and the associated Harmonics kon centered. These frequencies are through appropriate Measures then isolated or suppressed. The Natural frequencies of the structure are determined by constructive measures divided into several frequencies.

In an advantageous embodiment of which is the rotor with a Shaft bearing stored in its center of gravity. This has the advantage that the precision movement is tied up.

Advantageous is wider when the distance between the first and second shaft bearings is provided equal to the rotor height. this leads to to a bondage of the bending vibration / pitching vibration of the arrangement.

Of Further, it is still advantageous to wave between the two Thickening shaft bearings. This leads to increase the frequency of the torsional vibration.

For the diameter of the rotor, it is advantageous to provide it approximately equal to the height of the rotor in the manner of a symmetrical gyroscope. This leads to the degeneration of the moment of inertia. For the number of teeth m and the number n of the poles is advantageous to provide only an integer solution, where only the number of poles seven and twelve come into question, since the pole pair numbers one and two are uninteresting because of excessive torque nonuniformity / pulsation; the pole pair number five is difficult to realize in terms of production engineering and pole pair numbers greater than fifteen are too sensitive with regard to pitch errors.

It is advantageous to store the rotor in a needle bearing whereby the surface pressure and the wear of the Reduced wave in the contact zone.

It is also advantageous, the poles against the control grooves by indexing to align so that the pulsation is minimal.

If the rotor is arranged mirror-symmetrically, can be the pressure change forces minimize to the shaft.

The three phases of the stator are always advantageous against the intake The pump orients that torque of the DC motor when reversing becomes maximum.

Advantageous It is also when the rotor and the shaft bearings of fluid from the Reservoir to be flowed around, with the shaft in two hydrodynamic lubricated plain bearings can be stored.

A advantageous embodiment is seen in the assembly with screws on a flat surface aufzuspannen, where the assembly for acoustic insulation by soft seals on the end faces of the housing is clamped and no metallic Contacts between the assembly and housing take place.

to Improvement of the heat transfer between the pump housing and DC motor is the gap between the pump housing and the motor is advantageously filled with fluid from the reservoir.

The Gear pump includes in particular a gerotor pump, wherein the Housing of the toothed ring pump designed in three parts is and the second shaft bearing between the pump housing and Stator is provided, the shaft is inserted into the pump rotor and the permanent magnet is sintered together with the shaft.

at the DC motor or BLDC motor may be in an advantageous Way around a so-called "external rotor", in which the stator is arranged with the coils inside and coaxial surrounded by the rotor with the permanent magnets, or by a so-called "internal rotor" act, at the stator is attached to the housing and coaxial with the Rotor mounted on the shaft surrounds with the permanent magnets.

1

Annular gear pump

2

DC motor as an external rotor

3

common Shaft drive shaft

4

first shaft bearing

5

second shaft bearing

6

rotor as an external rotor

7

gap between DC motor and gear pump

8th

pump housing

9

pump cover

10

pump ring

11

circuit board

12

axial Write

13

pump bottom (Cover)

14

stator (6 pieces)

15

coil windings in the stator ring

16

stator of the DC motor

17

cylinder head screw

18

permanent magnets in the rotor

19

Iron yoke of the rotor (designed as a ring)

20

spacer made of non-magnetic material

21

pump rotor

22

motor shaft

23

pump shaft

30

gear pump

31

pump motor as an inner rotor

32

casing

33

ground

34

bearing cap

35

stator

36

pump cover to the engine

37

pump cover

38

pump rotor

39

pump ring

40

wave

41

rotor

42

connection

43

electronic circuit

44

Wall plug

45

first shaft bearing

46

second shaft bearing

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1255928 B1 [0003]
• - DE 4325502 C2 [0004]

Claims (26)

From a DC motor ( 2 . 31 ) driven gear pump ( 1 . 30 ) for conveying fluids with a pump rotor ( 21 . 38 ), which is provided with a drive shaft ( 3 . 22 . 23 . 40 ) of the DC motor ( 2 . 31 ) is rotatably connected, wherein the rotor ( 6 . 41 ) of the DC motor ( 2 . 31 ) made of permanent magnets ( 18 ) is formed with arranged in n pairs of poles, wherein at least one of the poles of the rotor ( 6 . 41 ) of the DC motor ( 2 . 31 ) associated permanent magnet ( 18 ) to the teeth of the pump rotor ( 21 . 38 ) is positioned such that system-related fluctuations in the torque of the gear pump ( 1 . 30 ) is counteracted, wherein the housing ( 8th . 9 . 13 . 32 ) of the gear pump ( 1 . 30 ) and the stator ( 16 . 35 ) of the DC motor ( 2 . 31 ) are rigidly connected to each other, wherein the common drive shaft ( 3 . 22 . 23 . 40 ) on one side in the stator ( 16 . 35 ) of the DC motor ( 2 . 31 ) and on the other side in the housing ( 8th . 9 . 13 . 32 ) of the gear pump ( 1 . 30 ) and wherein the n pole pairs of the DC motor ( 2 . 31 ) are radially aligned. Gear pump ( 1 . 30 ) according to claim 1, characterized in that the gear pump ( 1 . 30 ) a gerotor pump with a housing ( 8th . 32 ), an internal pump rotor ( 21 . 38 ) with gears and a pump rotor ( 21 . 38 ) surrounding pump ring ( 10 . 39 ) and that the product of number of rotor teeth m * and the number of toothed ring teeth m + 1 in a three-phase DC motor ( 2 . 31 ) is equal to the pole change frequency 6 * n, where m * (m + 1) = 6 * n. Gear pump ( 1 . 30 ) according to claim 1 or 2, characterized in that the rotor ( 6 . 41 ) of the brushless DC motor ( 2 . 31 ) and the pump rotor ( 21 . 38 ) of the gear pump ( 1 . 30 ) rigidly mounted on a shaft and in two shaft bearings ( 4 . 5 . 45 . 46 ) are included. Gear pump ( 1 . 30 ) according to one of claims 1 to 3, characterized in that the brushless DC motor ( 2 . 31 ) is a BLDC motor. Gear pump ( 1 . 30 ) according to one of claims 1 to 4, characterized in that the rotor ( 6 . 41 ) of the DC motor ( 2 . 31 ) with a shaft bearing ( 4 ) is stored in its center of gravity. Gear pump ( 1 . 30 ) according to one of claims 1 to 5, characterized in that the shaft bearings ( 4 . 5 ) are formed such that the distance between the first and second shaft bearings ( 4 . 5 ) equal to the height of the rotor ( 6 . 41 ). Gear pump ( 1 . 30 ) according to one of claims 1 to 6, characterized in that the shaft ( 3 ) between the two shaft bearings ( 4 . 5 ) is thickened. Gear pump ( 1 . 30 ) according to one of claims 1 to 7, characterized in that the rotor ( 6 . 41 ) is formed such that its diameter is almost equal to its height. Gear pump ( 1 . 30 ) according to one of claims 1 to 8, characterized in that the number of teeth m and the number n of the poles is an integer. Gear pump ( 1 . 30 ) according to claim 9, characterized in that the number of poles is seven or twelve. Gear pump ( 1 . 30 ) according to one of claims 1 to 10, characterized in that the shaft bearings ( 4 . 5 . 45 . 46 ) Needle roller bearings are. Gear pump ( 1 . 30 ) according to one of claims 1 to 11, characterized in that the poles are aligned against the control grooves such that the pulsation is minimal. Gear pump ( 1 . 30 ) according to one of claims 1 to 12, characterized in that the rotor ( 6 . 41 ) is arranged mirror-symmetrically. Gear pump ( 1 . 30 ) according to one of claims 1 to 13, characterized in that the three phases of the stator ( 16 . 35 ) in such a manner against the suction opening of the gear pump ( 1 . 30 ) are oriented so that the torque of the DC motor ( 2 . 31 ) becomes maximum when reversing. Gear pump ( 1 . 30 ) according to one of claims 1 to 14, characterized in that the rotor ( 6 . 41 ) and the shaft bearings ( 4 . 5 . 45 . 46 ) are flowed around by the fluid from the reservoir. Gear pump ( 1 . 30 ) according to one of claims 1 to 15, characterized in that the shaft bearings ( 4 . 5 . 45 . 46 ) are hydrodynamically lubricated plain bearings. Gear pump ( 1 . 30 ) according to one of claims 1 to 16, characterized in that the assembly is mounted with screws on a flat surface, wherein the assembly by soft seals on the end faces of the pump housing ( 8th . 32 ) is clamped and no metallic Kon between the module and the pump housing ( 8th . 32 ) occur. Gear pump ( 1 . 30 ) according to one of claims 1 to 17, characterized in that the gap ( 7 ) between pump housing ( 8th . 32 ) and DC motor ( 2 . 31 ) is filled with fluid from the reservoir. Gear pump ( 1 . 30 ) according to one of claims 1 to 18, characterized in that the gear pump ( 1 . 30 ) comprises a gerotor pump, wherein the pump housing ( 8th . 32 ) of the gear pump is designed in three parts and the second shaft bearing ( 5 . 46 ) between pump housing ( 8th . 32 ) and stator ( 16 . 35 ), the shaft ( 3 . 40 ) in the pump rotor ( 21 . 38 ) and the permanent magnet ( 18 ) together with the wave ( 3 . 40 ) is sintered. Gear pump ( 1 . 30 ) according to one of claims 1 to 19, characterized in that the DC motor ( 2 ) is a so-called "external rotor", in which the stator ( 16 ) with the coil windings ( 15 ) is arranged inside and coaxial with the rotor ( 6 ) with the permanent magnets ( 18 ) is surrounded. Gear pump ( 1 . 30 ) according to one of claims 1 to 20, characterized in that at least one of the radially oriented n poles of the permanent magnet ( 18 ) against the m teeth of the pump rotor ( 21 . 38 ) is rotated such that the pulsation of the gear pump ( 1 . 30 ) is minimized. Gear pump ( 1 . 30 ) according to one of claims 1 to 21, characterized in that the number m of the teeth of the pump rotor ( 21 . 38 ) with the number n of the poles of the rotor ( 6 . 41 ) is designed to be divisive. Gear pump ( 1 . 30 ) according to one of claims 1 to 22, characterized in that the DC motor ( 2 . 31 ) an electronics ( 11 . 43 ) that maps the magnetic field in the stator ( 16 . 35 ), wherein the magnetic field of the coils is set so that the system-related fluctuations in the torque of the gear pump ( 1 . 30 ) is counteracted. Gear pump ( 1 . 30 ) according to one of claims 1 to 23, characterized in that the phases of the stator ( 16 . 35 ) against an intake opening and / or an outlet opening of the gear pump ( 1 . 30 ) and that the torque of the DC motor ( 2 . 31 ) when switching from decompression to compression is maximal. Gear pump ( 1 . 30 ) according to one of claims 1 to 24, characterized in that the DC motor ( 2 . 31 ) and the gear pump ( 1 . 30 ) in a housing ( 8th . 9 . 13 . 32 ) are arranged that the shaft ( 9 ) of the DC motor ( 2 . 31 ) at its two ends in lids ( 3 . 6 ) of the housing ( 8th . 9 . 13 . 32 ) and the anchor ( 10 ) and the pump rotor ( 21 . 38 ) and that the fluid has lubricating properties and the DC motor ( 2 . 31 ) is filled with fluid. Gear pump ( 1 . 30 ) according to one of claims 1 to 25, characterized in that the covers ( 9 . 13 . 34 . 36 ) via soft seals on the front sides of the housing ( 8th . 9 . 13 . 32 ) are clamped.