DE2256142A1 - ELECTRIC MOTOR WITH COOLING DEVICE - Google Patents

Description

Patent attorneys

Dipl.-Ing.W.Beyer .. ^; Dipl.-Wirtsch.-Ing.B.Jochem

Frankfurt am Hain Freiherr-vom-Steln-Str.

In matters:

SKF Industrial Trading and
Development Company BV
Amsterdam, Netherlands
Overtoom

Electric motor with cooling device.

The invention relates to an electric motor with a stator, a rotor and radially inside the end-face winding heads attached to the stator, shell-shaped, the bearings of the rotor shaft receiving bearing housings, which concentric Rows of through holes for between the spaces in front of the front sides of the rotor and the spaces in front of the front sides of the stator and circulating around the winding heads Have cooling air.

In modern industry, the demands on production machines are constantly increasing, and they are expected of them an increasingly perfect mode of action. This leads to, among other things a continuous increase in the number of electric motors, with ever better efficiency, faster and should run with less vibrations, but at the same time should be smaller and lighter than before. Often it is it is also desirable that the temperatures developed during operation be lowered.

The desired properties of modern electric motors are technically not easy to achieve, and others

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BKF 8428 / November 15, 1972.

Difficulties have recently arisen from environmental awareness. This is often not compatible with the increased demands according to technical performance, e.g. not if the noise level in the workshop or in the Office should be lowered.

The increased temperatures and the high speeds of modern electric motors make an improved forced cooling, e.g. due to more effective cooling air fans, required. However, this in turn increases the noise level to such an extent that that there is a sound-insulating encapsulation of the entire

Motor unit with the associated air duct system as proved necessary to reduce the noise to an acceptable level. However, effective encapsulations need so much space that they represent an obstacle to the widespread use of electric motors in mechanical engineering. Pressure differences In the air ducts, dust contained in the air, moisture and dirt are other factors which hinder attempts to reduce noise. Special cooling air fans can also be aerodynamic and cause resonance vibrations, which not only affect human working conditions, but also the Deteriorate properties of the machines equipped with such electric motors.

The manufacturers of electric motors are aiming for smaller dimensions, but everyone has made progress in this direction only a small value in practice because of the higher operating temperatures of more compact motors. High speeds and heat resistant Materials are not a panacea in this context because of the pressure inside the engine during of operation becomes so high as a result of the rise in temperature that the required shaft seals will not function properly can. As a result, there is an exchange of air between the interior of the engine and the surrounding atmosphere, which is often overloaded with impurities. This brings "

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the go driving on red oron collapse or severe accident. chp; «- important things with yourself.

To the problems that exist with air-cooled electric motors Attempts have been made to resolve or turn off certain Types of engines with a liquid cooling system, "such as a Cooling water jacket, to be provided. These. The way of removing the heat loss is much more effective than the conventional one Air-cooled arrangements. There was a major disadvantage of the known cooling devices with water cooling However, so far it is still in the fact that during operation it is proportionate strong temperature differences between the various Adjusted parts of the engine. That which is in direct metallic contact with the cooling water jacket The stator core is cooled much more effectively than the inner areas of the stator and the frontal areas End turns of the stator windings. These temperature differences have a detrimental effect on the performance and service life of the engine »With a more uniform Engine temperature could increase performance while having other important properties as well Lifespan can be improved. Also, when the temperature of the air trapped in the engine is lowered that much could that it is only a few degrees above the ambient temperature, the pressure increase in the engine as a result of the temperature increase keep it low enough that the shaft seals and other pressure sensitive components function properly and prevent contaminants from entering the interior of the engine.

The invention is therefore based on the object of creating a motor of the type mentioned at the outset, in which a liquid and an air cooling are combined in such a sensible way that they mutually have their main disadvantages lift.

SKF 84-28 / 11/15/1972 309821/0318

2256H2

The above task is "in an electric motor with a Air cooling of the type referred to solved in that the stator is connected to it in a thermally conductive manner and extends axially over the winding heads through nine cooling liquid jacket is surrounded, the inner wall together with motor end walls that are connected to it and the bearing housings, delimiting the spaces in front of the stator, which flow paths for conveyed by the rotor, via certain holes in the bearing housings on the winding heads and then along the inner wall of the cooling liquid jacket form cooling air, which in the circuit after their Cooling down on the coolant jacket through other holes in the bearing housings back into the spaces in front of the end faces of the rotor is retractable.

An electric motor designed according to the new proposal will meet all technical requirements low vibration tendency, low operating temperature, small dimensions with high performance as well as a uniform meet internal temperature distribution. The engine works very quietly, as the usual strong fan is not needed and the liquid-filled housing parts effectively dampen the noises generated during operation. One Disturbance of the working conditions in the area of the engine through cooling air ducts, isolation chambers and similar special precautions, which sometimes also expose the operating personnel to an unpleasant train and endanger health, is eliminated.

The invention is explained in more detail below with reference to the drawing. Ed show:

1 shows a simplified one-sided axial section through an electric motor according to the invention,

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2 shows a simplified one-sided axial section

a motor end of a further embodiment,

3 shows a modification of a detail of the embodiment according to Fig. 2 in a view corresponding to this. . ■ *

In the different drawing figures are for identical. Parts the same reference numerals have been used.

1 shows an electric motor with a laminated stator core 1 with a winding 22, the end windings of which are denoted by 2. One sitting on a rotor shaft 4- The rotor 3 is aligned coaxially to the stator by means of bearings 24 and guided, which in cup-shaped bearing housings 5 and 6 which are attached to the end faces of the stator, for example by welding and via annular lugs 7 and 8 are. The bearing housings are in contact with a shoulder surface aligned coaxially to the stator axis. The cupped Bearing housings 5 and 6 are radially inward of the end turns 2 arranged the stator winding.

The laminated stator core 1 is surrounded by a cooling liquid smantel, the inner wall 9 of which rests tightly on the laminated stator core and extends axially beyond the end turns 2. Outside the inner wall 9 there is a channel system with circumferential channels 10 and 11 at the ends of the cooling liquid jacket. The circumferential channels are through a plurality of mutually spaced axial channels 12 connected. The canal system becomes outward closed by a shell forming the outer wall of the cooling liquid jacket. The cooling liquid is supplied via an inlet line 14 and discharged via an outlet line 15. The coolant supplied is denoted by 16. The direction of flow of the liquid along the channels of the

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The jacket is indicated by arrows 17. During the operation of the motor, the heat losses from the stator laminated core Derived via the inner wall 9 to the cooling liquid. If no further measures were taken, the Vicklungs heads 2 resulting heat in the stator core pass over to be routed from there to the coolant. Under these circumstances, the temperature of the end turns would rise sharply and become much higher than that of the Laminated stator core. If a strong, outwardly directed air flow is not directed against the winding heads, causes the heat to be radiated from the winding heads 2 the surface 18 of the cooling jacket exposed to this only a very slight reduction in the temperature of the winding heads. However, by directing an outwardly directed, vigorously circulating air flow around all winding heads, a very effective forced cooling of the same is achieved. This flow cycle of the air comes about that in the bearing housings 5 and 6 a system of radially inner, mutually spaced in series through-Iöchem19 and a series of radially outer through holes are provided. When the rotor 3 rotates, it becomes continuous Air flow 21 conveyed to the outside through the holes 20, which is forced through and over the windings 22 with their Winding heads 2 to flow. The air absorbs heat from the windings and thereby cools them. The air flow is stroking thereafter further outwards and comes into contact with the cooled inner surface 18 of the cooling liquid jacket, where the heat absorbed by the air from the windings is released very quickly. The cooling surface 18 can as through special measures increased area be formed. After the cooling air transfers the absorbed heat to the cooling fluid jacket has released, it becomes along a motor end wall 23> which is sealed with the cooling fluid jacket is connected to the radially inner row of through holes 19. Behind it, the air cools the bearing hub of the bearing housing and the bearing 24. By the rotation

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of the rotor, the cooling air is then passed through again to the outside the holes 20 promoted in order to cool the exposed stator windings again. On the way through the bearing housing it cools the end face 25 of the rotor and its short-circuit rings 26. Because of the effective Kühlimg the the winding heads 2 receiving spaces 27? can the temperature the circulating cooling air can be kept so low that the pressure increase caused by it is also very low remains small. A seal 28 at the end of the rotor shaft 4- led out is therefore to be expected to be trouble-free is working.

The shell 13 and the motor end walls 23 can be made of any suitable Material. When the heat radiation is optimal should be, metal would be preferable. If, on the other hand, noise attenuation has priority, these housing parts should be preferred made of plastic or rubber.

Another embodiment of the invention is shown in Fig. and FIG. 3 shows an electric motor which, in addition to a cooling liquid jacket around the stator, is also liquid-cooled End walls has:

The motor end wall 23 is made of pressed sheet metal and is hollow to allow a cooling liquid, e.g. Water. The cooling water is through the inlet pipe 14- fed to the cavity 29 via a channel 30. Next to the rotor bearing 24 is the inner wall of the double motor end wall bent inwards to enlarge the water reservoir and the cooling surface between the water and the bearing. In addition, the lift current in the motor becomes more suitable in this way Way redirected.

The cooling water flows out of the end wall through a not shown Outlet, which is preferably diametrically opposite the inlet 10 Diegt, to areas with stagnant water '

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avoid. The outlet can be located in the stator lamination package surrounding cooling water jacket extend.

In order to supply cooling water to both hollow end walls, a construction according to FIG. 3 can be chosen. There are two separate pipes or lines 31 mounted within the inlet line 14-, each of which provides a flow of water to the associated End wall leads. The lines 31 can be made of rubber, for example exist. Alternatively, they can also be cast. This can be useful, for example, if the shell or outer wall 13? In casting.

• Because the engine end walls are not exposed to great stress are, because the bearings are received in bearing housings supported on the stator core, the end walls can be attached and sealed in a simple and elegant manner. For example, Figure 2 shows an end wall 23 made of sheet metal compacts and a sheath 13 made of rubber. In the example, the end wall is connected to both the bearing housing by means of O-rings 32 5 as well as with the cooling fluid jacket 9. A clamping ring 33 holds the rubber sleeve 13 in tight contact on an axial flange 34 of the end wall. It takes in this No screw connections or similar expensive and complicated construction parts.

Patent claims /

SKF 8428 / 11/15/1972 309821 / 031R

Claims (6)

Claims Electric motor with a stator, a rotor and radial attached to the stator inside the end windings, shell-shaped bearing housings which accommodate the bearings of the rotor shaft and which have concentric rows of through-holes for between the spaces in front of the end faces of the rotor and the spaces in front of the end faces of the stator and around the Have circulating cooling air, characterized in that the stator (1) by a coolant jacket that is connected to it in a thermally conductive manner and extends axially beyond the winding heads (2) (9, 13) is surrounded, the inner wall (9) together with the motor end walls (23) with it and the bearing housings (5, 6) are connected, the spaces (27) at the front in front of the stator (1) bounded which flow paths for through the Rotor (3) promoted, through certain holes (20) in the bearing housings (5, 6), on the winding heads (2) and then on the inner wall (9, 18) of the coolant jacket (9, 13) along cooling air (21), which in the circuit after their cooling on the cooling liquid jacket over other Holes (19) in. The bearing housings (5, 6) back into the rooms in front of the end faces' of the rotor ($) is retractable. 2. Electric motor according to claim 1, characterized in that indicates that at least one of the motor end walls (23) is hollow and connected to the liquid cooling system (14). 3 · Electric motor according to claim 2 with two hollow motor end walls, characterized in that separate lines or pipes (31) are arranged within the inlet line (14) of the cooling liquid jacket (9 »13), 309821/0318 SKF 8428 / 11/15/1972 which coolant lead to the hollow engine end walls (23). 4. Electric motor according to claim 2, characterized in that that the outlet conduit of the hollow engine end walls (23) is diametrically opposite its inlet conduit (30; 31) is arranged. 5. Electric motor according to claim 2, characterized that at least one hollow motor end wall (23) is made from sheet metal pressings. 6. Electric motor according to claim 2, characterized in that that at the junctions between the motor end wall (23) and the coolant ~ jacket (9) and the bearing housing (5, 6) O-rings (32) elastic material are arranged, which direct contact between the cooling liquid and the bearing housing (5 »6) allow. SKF 8428 / 11/15/1972 30 9 8 21/0318 L e r s e i t e