WO2007000222A1

WO2007000222A1 - Method for the manufacture of an electric motor

Info

Publication number: WO2007000222A1
Application number: PCT/EP2006/005276
Authority: WO
Inventors: Helmut Pirthauer
Original assignee: Hans Heidolph Gmbh & Co.Kg
Priority date: 2005-06-25
Filing date: 2006-06-02
Publication date: 2007-01-04
Also published as: DE112006001363A5

Abstract

The invention relates to a method for the manufacture of an electric motor (1) that comprises a stator (4) and a rotor (5), a shaft (6) driven by the rotor (5), at least two bearings (7, 8) for the mounting of the shaft (6), end shields (9, 10) for the two bearings (7, 8), and a housing (3). Said method comprises the following steps: introducing the stator (4), the rotor (5), the shaft (6), the bearings (7, 8) and the end shields (9, 10) into the housing (3); positioning the end shields (9, 10), which can be moved within the housing (3), in an adjustment position by means of a predetermined adjusting force that is exerted on at least one of the two end shields (9, 10) in such a way that the end shields (9, 10) are pushed together and the adjusting force acts on the shaft (6) by the axial transmission of force via a form-fit; locking the end shields (9, 10) in the adjustment position that is consequent upon the action of the adjusting force, by means of clamping forces emanating from the housing (3). The invention further relates to an electric motor of this type, in which the end shields (9, 10) are force-locked in position within the housing (3) by means of contact pressure exerted by the housing (3).

Description

Applicant: Hans Heidolph GmbH & Co. KG

Method for producing an electric motor

The invention relates to a method for producing an electric motor having a stator and a rotor, a shaft driven by the rotor, at least two bearings for supporting the shaft, bearing plates for the two bearings and a housing. The invention further relates to such an electric motor.

Such electric motors are known and commercially available.

For example, DE 3726159 A1 shows an electric motor in which the stator is arranged between two centering pieces. The centering pieces store a shaft with a rotor. The two centering pieces are positively connected within the housing. For this purpose grooves are provided in the housing respectively, which the

Set centering pieces in their axial position. The applied to the centering on the shaft axial contact force can not be set or regulated directly. The force results from the position defined by the grooves and the axial tolerances of the individual parts. To compensate for such tolerances therefore spacers must be provided on the shaft.

The object of the invention is to show a way how an electric motor of the type mentioned input can be made cheaper.

This object is achieved by a method comprising the following

Steps includes:

Inserting the stator, the rotor, the shaft, the bearings and the end shields into the housing, Positioning of the bearing shields movable in the housing in a set position by means of a predetermined contact force, which is exerted on at least one of the two end shields so that the end shields are pushed towards each other while the contact force acts by axial force transmission by means of positive engagement with the shaft,

Fixing the end shields in the setting position by outgoing from the housing clamping forces.

In electric motors, an adjusting force is exerted on the shaft to avoid an imbalance on the bearing plates. As a result of the contact force emanating from the end shields, the bearings are pressed axially against the shaft. In motors according to the prior art, the end shields are fastened with screws to a housing tube, so that they can accommodate the force corresponding to the contact force and are fixed in their predetermined position in the housing. The exact strength of the contact force depends not only on the predefined by screw holes position of the end shields, but also on the respective dimensions of the end shields, bearings and the shaft, which vary within the manufacturing tolerances.

It is also known, the end shields by inwardly directed grooves in one

Fix the housing. Also in this type of fixation, the axially acting on the shaft pitch depends on the respective manufacturing tolerances. The force is thus different for each electric motor produced. If the forces are to be compensated, special spacers are used to compensate for the manufacturing tolerances. This can only be done in a second operation, so that the known in the art engines are quite expensive.

Since adjusting forces on the one hand to avoid imbalance must not be too low, on the other hand, however, lead to large Anstellkräfte damage to the bearings must be complied with in the manufacture of electric motors according to the prior art for the various components extremely small manufacturing tolerances. This causes high costs.

If, for example, the position in which the end plates are screwed to the housing tube, through screw holes with an accuracy of 1/10 mm given, this tolerance is added with manufacturing tolerances of the two end shields, the two bearings, the housing and the shaft, for example, each 1/10 mm to a maximum value of 0.8 mm.

Even with a very precise production, it is therefore necessary according to the prior art to compensate for manufacturing tolerances occurring in a specific electric motor by shims, which are arranged between one of the end shields and the associated bearing. The respectively required number or thickness of the shims is subject to fluctuations and must therefore be determined by consuming measurements for each motor. If necessary, an already assembled motor must be dismantled and the number of shims adjusted. This causes high costs and results in that in electric motors according to the prior art setting forces usually can not be specified precisely, but scatter in a relatively large interval.

In the method according to the invention a complex compensation of manufacturing tolerances by shims is not necessary. The end shields are made in the housing with the desired Anstellkraft, so pressed in the axial direction against the shaft. The resulting Anstellposition in which the end shields are fixed, is dependent on the manufacturing tolerances of the individual components of the electric motor. After fixing in the setting position, therefore, the bearing plates exert exactly the desired setting force on the shaft.

The desired contact force can be applied by a stamp or a kind of large screw clamp, so that the two end shields are pressed against each other in the axial direction and thereby press on the shaft. Preferably, a shoulder or a step is provided on the shaft, so that the desired, predetermined contact force is transmitted to the shaft via a positive axial force transmission. Under positive fit is to be understood that the shaft and the bearing or end shields have a corresponding shape, so that a movement of the two parts against each other is not possible and as a result forces are transmitted from one part to the other part. If, for example, an adjusting force of 5 ° is desired, then the two end shields are pushed against one another with a force of 5 °, for example with a punch, against the shaft and therewith. As soon as the end shields are fixed in the resulting setting position, a clamping force of 5ON is guaranteed. If, for example, the shaft has been somewhat longer in a given case, this automatically leads to a correspondingly greater distance of the end shields in the setting position and thus to a compensation of production tolerances that have occurred.

Thus, it is possible, even with deviating components, which may also be subject to larger manufacturing tolerances, in particular length tolerances, to achieve the desired contact force in a single operation. After fixing the end shields in their setting position, in which they act on the shaft with the desired contact force, for example, the punch or other mechanical clamping element for applying the contact force can be removed from the motor housing. In this way, very cost-effective engines, since the assembly is much easier and faster. At the same time no very small manufacturing tolerances must be met in the production of the individual components, so that the components themselves are much cheaper to produce.

The clamping forces for fixing the end shields in the housing, for example, be generated by two half-shells of a tubular housing are screwed together such that the end shields are fixed after tightening the screws between the half-shells. However, the clamping forces are preferably generated in that a housing tube is used as the housing, which is heated before the introduction of the stator, the rotor, the shaft, the bearings and the end shields, for example in an oven, so that the clamping forces upon cooling of the housing tube by thermal contractions. Changes in length associated with the contraction lead to a small change in the setting force. However, this small change anyway is essentially the same for all motors of a series, since it depends only on the temperature change in the cooling process, and is therefore unproblematic.

In this way one can achieve that the inner diameter of the housing tube when hiring the bearing plates is so large that it moves in the housing tube can be. Upon cooling, the housing tube contracts, so that clamping forces arise by which the end shields are fixed in their pitching position.

By applying the method according to the invention, a desired setting force can be preset with high accuracy in the case of an electric motor. Since a complex compensation of manufacturing tolerances is no longer required, this higher precision is also achieved with less effort than is the case in the prior art. Another cost saving results from the fact that the individual components of the electric motor can be manufactured with greater tolerances and therefore more cost-effective. In addition, screws for fixing the end shields are no longer required, so that components can be saved and the assembly can be simplified. The motor according to the invention is thus distinguished by the fact that the end shields are fixed in their position in the housing exclusively by the clamping forces emanating from the housing. Each motor of a series thus has exactly the same contact force, even if its individual components have different tolerances.

Further details and advantages of the invention will be explained in more detail using an exemplary embodiment with reference to the attached figures. The features illustrated therein may be used alone or in combination to provide preferred embodiments. Show it:

Figure 1 shows an electric motor according to the invention in longitudinal section. and FIG. 2 shows a prefabricated motor unit for the electric motor shown in FIG. 1.

The electric motor 1 shown in Fig. 1 comprises a motor unit 2, which is arranged in a housing tube 3. The motor unit 2 is shown separately in FIG. 2 and comprises a stator 4 and a rotor 5, one driven by the rotor 5

Shaft 6, two bearings 7, 8 for supporting the shaft 6 and end shields 9, 10 for the two bearings 7, 8. The motor unit also includes not shown small parts, such as wave washers. The bearings 7, 8 are ball bearings that press against the shaft 6 to avoid an imbalance with a predetermined contact force of example 5ON. The contact force is transmitted from the end shields 9, 10 respectively to the stationary bearing shell 7a and 8a, from there via the balls of the bearing on the rotating bearing shell 7b, 8b and finally from this to the shaft 6. The transmission of the force acting in the direction of the axis of the shaft 6 of the rotating bearing shells 7b, 8b on the shaft is effected by a shoulder, step or other suitable positive engagement between these two elements. In the case shown, the rotating bearing shells 7b, 8b sit for this purpose on portions of the shaft 6 with a reduced diameter. But there are also other constructions for the required axial force transmission possible, for example, the rotating bearing shell 7b, 8b of the bearing 7, 8 overlap the end face of the shaft 6 or the axial force transmission can be effected by means of a seated in a groove of the shaft 6 ring.

An important feature of the illustrated electric motor 1 is that the bearing plates 9, 10 are fixed in the housing 3 by clamping forces. In order to achieve this, the housing tube 3 of the electric motor 1 is inductively heated in the production, ie, by inducing a heating current, to a temperature of 200 ° C to 250 ⁰ C. Subsequently, the preassembled motor unit 2 shown in Fig. 2 is introduced into the heated housing 3. Preferably, a stop is attached to the front housing end, so that the front end shield 9 is positioned flush with the housing end. The position of the remaining parts of the motor unit 2 and in particular the position of the rear end plate 10 is obtained relative to the housing tube 3 then by the force exerted on the rear end plate 10 Anstellkraft. This adjusting force can be exerted, for example, with a punch, which dips into the housing tube 3. Under the action of the contact force, the bearing plate 10 shifts so long until a counterforce is exerted on the bearing plate 10 via the shaft 6, which counteracts the contact force.

The diameters of the end shields 9,10 are sized so that they are fixed by clamping forces in the housing tube 3, as soon as the housing tube contracts as a result of cooling. After cooling of the housing tube 3, the bearing plates 9, 10 and the motor unit 2 are positioned in the housing tube so that exactly the desired contact force of the bearing plates 9, 10 on the shaft 6 is practiced. After cooling, therefore, the punch and the stop, with which the contact force has been applied, can be removed, without this leading to a change in the position of the end plates 9, 10.

In the illustrated embodiment, the clamping forces act directly from the housing 3 on the bearing plates 9, 10. However, embodiments are also possible in which the power is transmitted from the housing 3 to the bearing plates 9, 10 via interposed further elements, wherein at least one Place the power flow between the housing 3 and the end shields 9, 10 clamping forces act.

An important advantage of the described manufacturing method is that for the individual parts of the motor unit 2 no very precise length tolerances must be specified and yet exactly the desired contact force can be realized. The exact Anstellposition of the end shields 9, 10 results in each case depending on the specific dimensions of the individual parts of a given electric motor 1. At one end of the housing tube 3 therefore results in a free space 13, the exact size of each resulting pitch position of the rear end shield 10th depends. This free space 13 can accommodate further components of the electric motor 1, for example plug 14, encoder and / or a brake.

Preferably, the stator 4 of the illustrated electric motor 1 is dimensioned so that it is also fixed by force exerted by the housing tube 3 clamping forces frictionally in position. For this purpose, for example, the stator winding can be dimensioned accordingly, so that the outer diameter of the stator 4 is slightly smaller than the inner diameter of the heated housing tube 3, the stator 4 but rests against the housing 3 at room temperature.

In operation, it may happen that the shaft 6, the two bearings 7, 8 and / or the end shields 9, 10 slightly warm. In order to be able to guarantee a desired setting force precisely despite a thermal expansion associated therewith, a plate spring 15 is arranged between at least one of the two bearings 8 and the associated end shield 10. In the illustrated embodiment, the plate spring 15 is arranged in a recess of the bearing plate 10, in which the associated bearing 8 is located. It can be seen from FIG. 1 that no grooves or screws are provided in the housing 3 for fixing the end shields 9, 10. The bearing plates 9, 10 and the stator 4 are fixed exclusively by a frictional connection, ie they are held only by an external force, namely the clamping force, in their mutual position within the housing. The frictional holding stands in contrast to the positive engagement, since in this case no corresponding shape between the parts to be joined, such as grooves, shoulders or shoulders, must be provided. The fixation is thus form-fitting.

As the material for the housing tube 3 aluminum alloys, in particular spring-hard aluminum alloys such as AlMgSi alloys are preferred. Aluminum alloys have an advantageously large thermal expansion coefficient, so that there is sufficient for the described method bene thermal expansion at temperatures of 15O ⁰ C to 250 ⁰ C. In addition, aluminum alloys have sufficient hardness, so that over the expected life of the electric motor 1 is always a sufficient clamping force on the end plates 9, 10 is exercised.

Claims

claims

A method of manufacturing an electric motor (1) comprising a stator (4) and a rotor (5), a shaft (6) driven by the rotor (5), at least two bearings (7, 8) for supporting the shaft ( 6), bearing plates (9, 10) for the two bearings (7, 8) and a housing (3), the method comprising the following steps:

Inserting the stator (4), the rotor (5), the shaft (6), the bearings (7, 8) and the end shields (9, 10) in the housing (3),

Positioning of the bearing plates (9, 10) which are movable in the housing (3) in a setting position by means of a predetermined setting force which is exerted on at least one of the two bearing plates (9, 10) such that the bearing plates (9, 10) are pressed towards one another while the Anstellkraft by axial force transmission by means of positive engagement on the shaft (6) acts, - fixing the end shields (9, 10) in the resulting under the effect of the Anstellkraft Anstellposition by the housing (3) outgoing clamping forces.

2. The method according to claim 1, characterized in that the shaft (6) has a shoulder or step for the positive axial power transmission.

3. The method according to claim 1 or 2, characterized in that the bearing plates (9, 10) are fixed non-positively in their setting position in the housing (3) by the clamping forces.

4. The method according to any one of the preceding claims, characterized in that a housing tube (3) is used as the housing, which is heated before the introduction of the end shields (9, 10) and the clamping forces are generated by cooling the housing tube (3).

5. The method according to any one of the preceding claims, characterized in that the rotor (5), the stator (4), the shaft (6) and at least one bearing plate (9) with the associated bearing (7) as a preassembled motor unit (2) be introduced into the housing (3).

6. The method according to any one of the preceding claims, characterized in that one of the two end shields (9) is fixed by a releasable stop, while the other bearing plate (10) under the action of the Anstellkraft in the Anstellposition, in which it is then fixed by clamping forces , on the

Shaft (6) is pushed.

7. The method according to any one of the preceding claims, characterized in that the adjusting force is exerted by a punch, which dips into the housing (3).

8. The method according to claim 6 or 7, characterized in that the stop and / or the punch are removed from the housing after the end shields (9, 10) are held by the clamping forces in their Anstellposition in the housing (3).

9. Electric motor, in particular produced according to one of the preceding claims, comprising a stator (4) and a rotor (5), one of the rotor (5) driven shaft (6), at least two bearings (7, 8) for supporting the shaft (6), bearing plates (9, 10) for the two bearings (7, 8) and a housing (3), characterized in that the bearing plates 9, 10) by force exerted by the housing (3) clamping forces in their position in the housing (3) are fixed.

10. Electric motor according to claim 9, characterized in that the bearing plates (9, 10) are fixed exclusively by the force exerted by the housing (3) clamping forces in their Anstellposition in the housing (3).

11. Electric motor according to claim 9 or 10, characterized in that the housing is a housing tube (3).