DE102010039969A1 - Floating bearing device for bearing rotor shaft of electric machine, has end shield provided with hole, in which sockets are backlash afflicted and lubricant-free supported, so that sockets are freely displaceable in axial direction - Google Patents

Abstract

The floating bearing device has a radial bearing (2) which is encased into the sockets (3,4) and is not movable in the axial direction of the rotor shaft (1). An end shield (5) is provided with a hole, in which the sockets are backlash afflicted and lubricant-free supported, so that the sockets are freely displaceable in axial direction within the hole.

Description

The invention relates to a movable bearing device for supporting the rotor shaft of an electric machine. An ordinary dynamoelectric machine includes a housing, a stator disposed inside the housing, and a rotor seated on a shaft. The usually having a laminated core rotor is rotatably mounted on the shaft. The rotor shaft with the rotor laminated core is rotatably mounted at the end-side axial ends of the rotor by means of rolling bearings relative to the stator and the housing of the electric machine.

Usually located at one of the front ends of the rotor shaft, a fixed bearing, by which the rotor shaft is mounted both in the axial direction and in the radial direction. Under the axial direction is understood here and in the entire application, the corresponding with the axis of symmetry of the rotor shaft direction. Accordingly, radial direction is any direction orthogonal to the axial direction.

At the other end face of the rotor shaft or the rotor laminated core is a floating bearing. This supports the rotor shaft radially but not axially. The floating bearing function is required to accommodate differences in the thermal expansion of the rotor shaft and housing and to prevent so that the bearings are destroyed by axial pressure.

Frequently, electrical machines and thus also the rolling bearings are installed in systems that are exposed to a variety of vibration states. Speed-controlled motors often pass through mechanical resonance points, which can result in considerable wear on the sliding bearing rings of the floating bearing. This abrasion, which occurs in the form of fretting corrosion, soils the bearing grease and leads to premature bearing damage.

In practice, motors are therefore completely decoupled from the environment by separate damping elements, for example made of rubber, in order to keep the vibration load away from the bearings.

Furthermore, an attempt is made to decouple the vibrations from the bearings, that the spring tension of the springs, which are used for the axial adjustment of the floating bearing, is very high. As a result, but the bearing size or the bearing type is usually changed with or reduced the bearing life and accepted approvingly accepted.

From the US 5 577 847 B It is known to arrange the floating bearing in a ring to prevent abrasion corrosion, which is movable within a bore of a bearing plate in the axial direction. With different thermal expansions of rotor shaft and housing, this ring can move slidably within the bore on a lubricating film. To hold the lubricant between the outer surface of the ring and the inner surface of the bore, rubber seals are provided between the ring and bore.

The invention has for its object to further increase the life of floating bearings.

This object is achieved by a movable bearing device for supporting a rotor shaft of an electric machine with the features according to claim 1.

• – ein Radiallager,
• – eine das Radiallager kapselnde und in axialer Richtung der Rotorwelle betrachtet bezüglich des Radiallagers nicht verschiebbare Buchse und
• – ein Lagerschild mit einer Bohrung, in der die Buchse spielbehaftet und schmiermittelfrei gelagert ist, so dass sie innerhalb der Bohrung frei in axialer Richtung verschiebbar ist.

Such a movable bearing device comprises

• - a radial bearing,
• - A radial bearing encapsulating and considered in the axial direction of the rotor shaft with respect to the radial bearing not displaceable socket and
• - A bearing plate with a bore in which the socket is mounted play and lubricant-free, so that it is freely displaceable within the bore in the axial direction.

Advantageous embodiments of the invention can be found in the dependent claims.

By using a sleeve freely axially displaceable within the bore, the bearing, which is designed in particular as a rolling bearing, can not deflect. Nevertheless, on the outer circumference of the bush, the movable bearing function can be realized within the bearing plate, which is required to accommodate different thermal expansion of the rotor shaft and housing. A possible abrasion from the sliding seat can not get into the camp interior due to the encapsulation surrounding the bearing. In this way, fretting corrosion is reduced and prevents it, if it nevertheless arises, can damage the bearing and the grease.

Particularly advantageous in this case is the inventive lubricant-free storage of the bushing with respect to the bore. Because compared to the prior art, this can be dispensed with the O-rings between the bush and bore, which are needed to hold the lubricant at the interface between the bore and socket. The invention is based on the finding that such O-ring solutions result in a certain hysteresis with changing changes in length of shaft or housing. Because, that radial bearing is employed by a spring in the axial direction on the floating bearing side. Before this spring position can move the bearing or the socket, when using O-rings, the Balls in the bearing relieved axially, which leads to unclean rolling operations in the warehouse. In turn, these unclean rolling operations lead to material wear in the bearing interior and thus to reduced bearing life.

The proposed here lubricant and thus O-ring-free solution, this hysteresis can be avoided. The axial displaceability of the bush is significantly better than that of the prior art O-ring solutions. Even a relatively soft adjustment spring alone can muster the necessary force to track the socket when the shaft shortens. This prevents unclean rolling operations in the warehouse and thus wear.

In an advantageous embodiment of the invention, bearing damaging bearing currents can furthermore be avoided in that the bush is electrically insulating and in particular consists of plastic or a composite material. By using an insulating material for the socket, a flow of current through the bearing can be prevented.

In a further advantageous embodiment of the invention, the radial bearing on a cage made of brass or plastic, to completely prevent the Schwingreibverschleiß within the bearing.

A deflection of the rolling bearing can be prevented, for example, characterized in that the radial bearing is pressed radially into the bushing. As an alternative to this interference fit, the radial bearing can also be clamped axially firmly, so that an axial displacement of the bearing relative to the bushing is prevented.

An electric machine with a movable bearing device according to one of the embodiments described above can expect a high bearing life even under increased vibration loads.

In the following the invention will be described and explained in more detail with reference to the embodiments illustrated in the figures. Show it:

1 a section through a bearing device according to an embodiment of the invention and

2 an electrical machine with an embodiment of the storage device according to the invention.

1 shows a section through a bearing device according to an embodiment of the invention.

Shown is the floating bearing side. The bearing device comprises a bearing plate 5 , a radial bearing 2 and one of two socket halves 3 ; 4 existing socket for encapsulating the radial bearing 2 , The radial bearing 2 has a cage consisting of an inner bearing shell 6 and an outer bearing shell 8th as well as bullets 9 , which is a rolling movement of the outer bearing shell 8th opposite the inner bearing shell 6 enable. The two socket halves 3 ; 4 are by a bolt 10 connected with each other. An O-ring 11 is provided for sealing to completely protect the bearing from dirt and moisture.

The radial bearing 2 is in the socket 3 . 4 pressed radially, so that it is opposite the socket 3 . 4 can not move in the axial direction.

The socket 3 . 4 is in turn in a hole of the bearing plate 5 , Opposite this hole has the bushing 3 . 4 a sliding seat on, leaving the socket 3 . 4 viewed in the radial direction displaceable relative to the end plate 5 is arranged. By a positioning spring 12 becomes the jack 3 . 4 pressed with a defined pressure in the direction of the rotor core. Due to thermal cycles, the rotor shaft now expands 1 in the axial direction, so does the complete socket 3 . 4 against the adjusting spring 12 pressed. The radial bearing 2 is not burdened with significant axial forces. Rather, the bush slides 3 . 4 further into the bore of the bearing plate 5 into it.

The special feature is that the surfaces of the bore of the bearing plate 5 and the socket 3 . 4 In the area of their contact surfaces are sufficiently low friction, so that can be dispensed with a lubricant. As a result, the use of O-rings for sealing the lubricant is obsolete, so that the above-described disadvantages of an O-ring-related known from the prior art solution can be avoided.

Advantageously, the socket 3 . 4 made of a non-electrically conductive material, such as plastic. This will prevent currents through the radial bearings 2 flow, leading to damage to the lubricant and thus the bearings.

2 shows an electric machine with an embodiment of the storage device according to the invention. The electric machine 7 can also be operated without separate damping elements in a vibration-prone environment, since the movable bearing device according to the invention before the camp Protects against contamination by fretting corrosion and thus prevents premature bearing failure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5577847 B [0007]

Claims (6)

Loslagereinrichtung for supporting a rotor shaft ( 1 ) an electric machine with - a radial bearing ( 2 ), - a radial bearing ( 2 ) encapsulating and in the axial direction of the rotor shaft ( 1 ) with respect to the radial bearing ( 2 ) non-displaceable socket ( 3 . 4 ) and - a bearing plate ( 5 ) with a bore in which the bush ( 3 . 4 ) is loaded with play and lubricant-free, so that it is freely displaceable within the bore in the axial direction. Bearing device according to claim 1, wherein the bushing ( 3 . 4 ) is electrically insulating and in particular made of plastic or a composite material. Bearing device according to claim 1 or 2, wherein the radial bearing ( 2 ) a cage ( 6 ) made of brass or plastic. Bearing device according to one of the preceding claims, wherein the radial bearing ( 2 ) radially into the bushing ( 3 . 4 ) is pressed. Bearing device according to one of the preceding claims, wherein the radial bearing ( 2 ) within the socket ( 3 . 4 ) is axially braced. Electric machine ( 7 ) with a movable bearing device according to one of the preceding claims.

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