DE10245016B4 - Electric motor with spherical rotor - Google Patents

Abstract

electric motor comprising a runner (106), a stator (110) and a bearing (136) through which the rotor (106) spherical is stored, wherein the bearing (136) has a bearing shell (140) with a central material-free area (150) and one slidable in the bearing shell arranged spherical sliding (138) and the runner (106) is formed magnetic field generating, characterized that the Bearing shell (140) has a central material-free region (150), which is designed so that the The force vector of spherical sliding (138) total reaction force (168) exerted on the bearing shell (140) is directed to the central material-free area (150) when an asymmetry between runners (106) and stator (110) is present and that a diameter (M) of the central material-free area (150) is equal to or greater than 0.44-fold the diameter (d) of the spherical one sliding (138).

Description

The The invention relates to an electric motor comprising a rotor Stator and a bearing through which the rotor is mounted spherically, wherein the Bearings a bearing shell and slidably disposed in the bearing shell Includes spherical slider and the runner is formed magnetic field generating.

Electric motors comprising a rotor, a stator and a bearing, through which the rotor is mounted spherically, wherein the bearing comprises a bearing shell and a slidably disposed in the bearing shell spherical sliding body are used in particular in centrifugal pumps. They have the advantage that it can be achieved over a largely play-free storage of the rotor. Such electric motors are for example in the DE 33 02 349 A1 or DE 1 538 717 A described. In the DE 29 02 492 A1 there is disclosed a rotor support with a bearing for automatically positioning a rotor by a fluid, the bearing being provided with a rotating bearing surface which causes a pressure increase by rotation with respect to a stationary bearing surface in the fluid, the fluid pressure generated being used for axial positioning of the rotor on a path bounded by a stop.

The nearest state of the art is from the GB 2 213 208 A a motor unit for a centrifugal pump, in which a rotating cap is mounted on a stationary ball. The cap has a central material-free region in the form of a channel.

Of the Invention is based on the object, an electric motor of the above to create said type, which at a high degree of freedom in terms of the outer dimensions having a largely backlash-free storage of the rotor.

These Task is in the above-mentioned electric motor according to the invention thereby solved, that the Bearing shell has a central material-free area, which is designed so that the The force vector of spherical sliding exerted on the bearing shell Total counterforce directed to the central material-free area is when there is an asymmetry between rotor and stator and the existence Diameter of the central material-free area is equal to or greater than 0.44 times the diameter of the sliding body.

If the runner Magnetfelderzeugend is formed, in particular over on the runner arranged permanent magnetic magnetic poles, then can be the runner form with low axial height and with that in turn can be the electric motor according to the invention with low axial height form. In particular, can be then a circulation pump, in which such an electric motor is used, with less axial height form.

electric motors with permanent magnetic runners have a high efficiency, since the runners generate no losses.

at low height of the runner is then but an axial component of the magnetic force accordingly low. Furthermore, lines of force run between the rotor and a yoke element of the stator diverging, so that at Asymmetry of the runner with respect to the Stators radial force differences can occur. In particular, for one Magnetic pole, which closer to the stator lies, the radial forces greater than for one diametrically opposite Magnetic pole, which is located more distant from the stator. Take the radial forces doing so with a reduced distance to the stator strongly. Especially in conjunction with a reduced axial component of the magnetic force means this then, that the resulting total force resulting from the hydraulic force and the total magnetic force, has a force vector, which off-center with a radial component hits the bearing shell. This power leads to a non-spherical Wear in particular in the bearing shell, in which the spherical sliding body slides. As a result, the geometric (spherical) shape is lost because a one-sided removal exists. In the bearing shell, an annular channel arise, softer to a recording of a unilateral rolling motion leads. This not full-surface Sliding motion on spherical Sliding body leads to imbalance, increased running noise and further wear.

Next a mechanical asymmetry between rotor and stator can also non-symmetrical forces by unbalanced magnetization (anisotropic magnetization arise); these can result in a non-axial total force.

The inventive solution now a central material-free area is provided so that even with asymmetry between the rotor and stator (for example, mechanical eccentricity and / or magnetic anisotropy) no material removal can take place on the camp (which, for example, could result in different peripheral speeds). The inventive solution can therefore be a permanent magnetic rotor use, for example, to minimize the height of the electric motor, the Proble me are avoided due to non-spherical wear on the bearing.

Basically it is possible that the spherical sliding on the runner is arranged and arranged the bearing shell rotatably relative to the stator is. It is advantageous if the bearing shell rotatably disposed on the rotor is and the spherical one sliding rotatably re of the stator is arranged. This results, for example, a easy lubrication of the warehouse, for example via a conveying fluid a circulation pump, in which the electric motor is used.

Especially it is envisaged that the runner for Magnetic field generation comprises one or more permanent magnets. There are then over the scope of the runner For example, distributes four or six magnetic poles with alternating Arranged polarity.

Especially it is envisaged that the runner a the stator and in particular a yoke ring of the stator facing Spherical surface area so as to have a spherical motor to build.

It is then an air gap between rotor and stator by spaced Spherical surface areas educated.

All it is particularly advantageous if the central material-free area is arranged around a lubrication hole or forms a lubrication hole. It let yourself then also lubrication fluid over this central material-free area to the sliding surfaces respectively of the spherical one Gleitkärpers and feed the bearing cup; a sliding surface the bearing shell is in particular concave.

Farther is it cheap if the central material-free region in particular rotationally symmetrical around an axis of the runner is formed, so that the Starting point for The central material-free area is the ideal case where runner and stator are in the middle. It can then be asymmetries in all radial Capture directions.

Cheap is it, if the bearing shell has a hollow cylindrical section and a spherical section which, in the axial direction of the hollow cylindrical Section follows. In these sections, then the spherical slider is immersed, being on concave walls of the spherical Section supporting slides.

Of the Central material-free area is advantageously in the spherical Section formed because there is the concave sliding surface of the bearing shell.

All it is particularly advantageous if a diameter of the central material-free area depending on set by manufacturing tolerances. If it is guaranteed that runners and Stator are exactly symmetrical and the magnetization is isotropic, then the central material-free area is minimized. Here but due to manufacturing tolerances this particular in mass production can not be guaranteed, the central material-free area be provided with appropriate dimensioning. Regarding yet tolerable manufacturing tolerances then becomes the maximum (and still tolerable) Asymmetry used to the central material-free area to dimension, as a sum of mechanical and magnetic Asymmetry. For this maximum deviation from the (spherical) symmetry becomes the Position of the resulting total force vector is determined, in which case this must hit the central material-free area and not on material areas of the bearing shell. It can then be ensured that no non-spherical Wear of the Warehouse takes place.

It has proven in practice to be sufficient when the diameter of the central material-free area is equal to or greater being 0.44 times and especially equal to or greater than 0.5 times the diameter of the spherical slider. at larger manufacturing tolerances preferably a diameter of the central material-free area equal to or greater than 0.6 times the diameter of the spherical slider.

Especially is a diameter of the central material-free area smaller than the diameter of the spherical slider so that one more concave support surface for the spherical sliding body in the bearing shell is present.

Of the Electric motor according to the invention can in a circulating pump be used, which is then a centrifugal pump.

The The following description of a preferred embodiment is used in conjunction with the drawing of the closer explanation the invention. Show it:

1 a sectional perspective view of an embodiment of a circulating pump according to the invention;

2 a schematic sectional view taken along the line 2-2 according to 1 wherein the magnetic field profile is shown in a magnetic field generating rotor according to the invention;

3 compared to 2 schematically the field line profile when the stator is magnetic field generating (prior art);

4 schematically a partial view of the rotor and the stator and the forces acting, and

5 a partial view of an embodiment of a bearing according to the invention for the storage of the rotor.

An embodiment of an electric motor according to the invention, which in 1 as a whole with 100 is part of a circulating pump 102 so that a pump-motor unit is formed. The circulation pump 102 includes a housing 104 in which the electric motor 100 is arranged. The circulation pump 102 is, as described in more detail below, designed as a centrifugal pump.

The electric motor 100 has a runner (rotor) 106 on. Connected to this rotatably is a paddle wheel 108 to form a rotor-paddle wheel unit.

The electric motor 100 further comprises a stator 110 with one or more windings 112 and a soft magnetic yoke ring 114 , The stator 110 is rotationally fixed in the housing 104 arranged.

The runner 106 is formed magnetic field generating. For this purpose it comprises one or more magnetic elements 116 which are in particular permanent magnets, which are magnetized via a radial direction. In particular, the magnetic elements 116 formed by permanent magnets of high coercive force, wherein the magnetic poles of the individual magnetic elements over the circumference of the rotor 106 arranged with alternating polarity.

A the stator 110 facing surface 118 of the runner 106 is part of a spherical surface, wherein the magnetic elements 116 follow this surface shape. To protect the magnetic elements 116 points the runner 106 a sheath 120 on, which is made of plastic or stainless steel, which is the surface 118 forms.

The spherical surface 118 corresponds to a portion of an imaginary sphere, which is perpendicular to an axis 122 ( 4 ), which runs through the center of the imaginary sphere, was cut. A the case 104 allocating area 124 of the runner 106 thus has a substantially flat surface. The same applies to one area 126 of the runner 106 , which the paddle wheel 108 assigns.

The winding or windings 112 of the stator 110 are the runner 106 arranged surrounding.

Between the runner 106 and the stator 110 and in particular its yoke ring 114 is an air gap 128 formed for magnetic inference. Spaced spherical surface areas, namely the surface 118 and an opposite spherical surface 130 one the winding or windings 112 surrounding wall 132 , form part of this air gap 128 , The wall 132 acts as a partition to the wet areas of the circulation pump 102 ,

The runner 106 is spherical, so as to form a centrifugal pump. A corresponding warehouse 136 comprises a ball-shaped spherical slider, for example 138 which is on a support column 134 ( 4 ) sits. This support column is rotationally fixed in the housing 104 arranged. A center of the spherical slider 138 sits on the axle 122 of the runner. Further, the center of the spherical slider falls 138 essentially together with the center of the imaginary sphere, which is the surface 118 forms.

The warehouse 136 further comprises a bearing shell 140 ( 5 ), which is made of coal, for example. The spherical slider 138 , which is made of a hard material and in particular ceramic material, relative to the bearing shell 140 slide in this. The bearing shell 140 is rotatable with the runner 106 connected. This then allows a largely backlash-free storage of the rotor 106 in the case 104 realize.

The bearing shell 140 includes, as in 5 shown a hollow cylindrical section 142 with a diameter D, which is substantially a ball diameter d of the spherical slider 138 equivalent. Between the spherical slider 138 and a bearing shell wall 144 can be an air gap 146 be formed, whose extension transverse to the axis 122 is considerably smaller than the diameter d of the spherical slider 138 ,

On the hollow cylindrical section 142 follows in the axial direction (in the direction of the axis 122 ) a spherical section 148 , wherein the center of the imaginary sphere forming this spherical section is the center of the spherical slider 138 which is a sliding ball for the bearing 136 is, coincides. A radius R of this imaginary sphere, which is the spherical section 148 forms, corresponds substantially to the radius d / 2 of the ball of the spherical slider 138 ,

Around the axis 122 of the runner 106 is in the bearing cup 140 a central material-free area 150 educated. This is so in the spherical Ab cut 148 arranged and stands over the spherical section 148 in conjunction with the hollow cylindrical section 142 , This central material-free area 150 is spherically symmetric with respect to the axis 122 formed and has a diameter M on.

The central material-free area 150 forms a lubrication hole, over which a lubrication medium such as pumped liquid of a sliding surface 152 of the spherical slider 138 and a sliding surface 154 the bearing shell 148 especially at the spherical section 148 can be fed.

The spherical slider 138 , which is at the support column 134 is sitting in the hollow cylindrical section 142 the bearing shell 140 immersed and is above the spherical section 148 relative to the bearing shell 140 slidably. About the spherical section 148 can be axial and radial forces of the rotor 106 on the spherical slider 138 transfer. Accordingly exercises then the spherical slider 138 a drag on the runner 106 and thus on the bearing shell 140 out.

The runner 106 is about the magnetic elements 116 magnetic field generating, that is, the magnetic field goes from the rotor 106 out. In 2 is shown schematically the field line course. In the air gap 128 run lines of force 156 between the runner 106 and the soft magnetic yoke ring 114 of the stator 110 , These run but not parallel, but have a relatively strong curvature. As a result, if the runner 106 off-center with respect to the stator 110 is shifted, that is, in particular, if an axis 158 of the stator 110 and the axis 122 of the runner 106 no longer coincide, large radial force differences occur; a magnetic pole of the magnet 116 , which due to the eccentricity closer to the yoke ring 114 lies, experiences a greater radial force than the diametrically opposite magnetic pole, which is a greater distance from the yoke ring 114 Has. When you move out of a centric position takes so that at the yoke ring 114 Magnetic pole closer to the radial force, while it decreases at a diametrically opposite magnetic pole. This causes stability problems during storage.

In comparison, for a non-inventive device in 3 a similar view as in 2 shown, where here is a stator 160 with a winding 162 is magnetic field generating. Between a runner 164 and the stator 160 run lines of force 166 , which are approximately parallel. In an eccentric deflection therefore occur substantially no radial force differences, so that an eccentricity does not affect the storage.

Besides or instead of an asymmetry between runners 106 and stator 110 Due to relative off-center positions, asymmetries in the magnetization or asymmetrical configurations of air gap boundaries can also lead to a resulting magnetic force having a radial component.

The central material-free region according to the invention 150 now ensures that the problems and in particular wear problems due to asymmetry such as eccentricity between the runner 106 and the stator 110 as related to 2 described are largely avoided.

The runner 106 experiences a force which is composed of the hydraulic force and the resulting magnetic force. He acts with a resultant force on the spherical slider 138 whose resulting total counterforce 168 ( 4 ) from the spherical slider 138 on the bearing shell 140 is exercised. The resulting total drag 168 is the resultant of the hydraulic drag 170 and the resulting counter magnetic force 172 , If the runner 106 is arranged centrally, that is its axis 122 with the axis 158 of the stator 110 coincides, then in isotropic magnetization, the radial component of the resulting counter-magnetic force 172 Zero and the resulting total drag 168 acts in the axial direction of the axis 122 ,

Is however the runner 106 unbalanced with respect to the stator 110 , for example, by a parallel axis offset between the axes 122 and 158 is present as in 4 shown, then lead the divergent lines of force in a magnetic field generating rotor 106 to the fact that a radial force difference exists. In addition, since the axial portion of the resulting counter-magnetic force 172 is relatively small when the runner 106 with its magnetic elements 116 a low height in the axle 122 has, this means that the resulting counterforce 168 , as in 4 shown no longer in the same direction as the hydraulic counterforce 170 that is on the axis 122 but at an angle to it.

This would mean that in asymmetry between runners 106 and stator 110 the spherical slider 138 Off-center on the bearing shell 140 presses and the bearing shell 140 thereby undergoes a corresponding wear. The corresponding wear area on the bearing shell 140 is not spherical symmetric. It would form an annular channel in her, which in turn leads to the bearing shell 140 when rotated around the spherical slider 138 a one-sided Rolling receives, instead of the entire surface on the spherical surface of the spherical Gleitkkörpers 138 to glide. This leads to an imbalance, to increased noise and to further increasing non-spherical wear.

According to the invention is now the central material-free area 150 arranged and designed so that the resulting total counterforce 168 just hit on a material-free area, that is on a cut-free area. This is so large that the force vector hits fluid, but not on solid material of the bearing shell 140 , As a result, even with oblique force vectors no non-spherical wear of the bearing shell 140 arise, so that for a long time the largely backlash-free storage of the rotor 106 in the case 104 is guaranteed.

The diameter M of the central material-free area 150 is particularly dependent on manufacturing tolerances including anisotropies in the magnetization of the rotor 106 chosen: The smaller the manufacturing tolerances are, the smaller this diameter can be selected. The manufacturing tolerances relate to the dimension and design of the spherical slider 138 , the spherical section 148 , the axial accuracy of the arrangement of the spherical slider 138 at the support column 134 , the axial accuracy of the stator 110 , the isotropy of magnetization, etc., and these quantities are also related to each other.

If due to manufacturing tolerances a maximum (tolerable) deviation of the symmetry between runners 106 and stator 110 is expected, then the diameter M of the central material-free area should be 150 be set so that the resulting total counterforce 168 still with their force vector on this central material-free area 150 meets.

It has been shown in practice that it is advantageous if M is at least 0.5 times as large as the diameter d of the spherical slider 138 , It has proven to be particularly advantageous if M is at least 0.6 times as large as the diameter d of the spherical slider 138 ; M is due to the spherical section 148 smaller than the diameter d of the spherical slider 138 ,

The inventive solution can be electric motors 100 and circulation pumps 102 realize which is a small height in the direction of the axis 158 exhibit; For example, this height can be less than 4 cm in total. This can be achieved if the runner 106 is magnetic field generating via permanent magnet poles. This results in a small axial component of the magnetic force and in an unfavorable for the storage radial component of the magnetic force when an asymmetrical arrangement is present.

By providing a central material-free area 150 These problems are reflected in their impact on the warehouse 136 solved; through this central material-free area 150 , which is chosen so that the total resulting total counterforce 168 does not encounter a solid state material, a non-spherical wear of the bearing shell 140 prevents which otherwise at different rotational speeds of the ball and thus, for example, to increased rough running and to a reduced life of the electric motor 110 could lead.

Claims (15)

Electric motor comprising a rotor ( 106 ), a stator ( 110 ) and a warehouse ( 136 ) through which the runner ( 106 ) is spherical, the bearing ( 136 ) a bearing shell ( 140 ) with a central material-free area ( 150 ) and a slidably disposed in the bearing shell spherical sliding body ( 138 ) and the runner ( 106 ) is formed magnetic field generating, characterized in that the bearing shell ( 140 ) a central material-free area ( 150 ), which is designed such that the force vector of the spherical sliding body ( 138 ) on the bearing shell ( 140 ) applied total counterforce ( 168 ) to the central material-free area ( 150 ) is directed, if an asymmetry between runners ( 106 ) and stator ( 110 ) and that a diameter (M) of the central material-free region ( 150 ) is equal to or greater than 0.44 times the diameter (d) of the spherical slider ( 138 ). Electric motor according to claim 1, characterized in that the bearing shell ( 140 ) rotatably on the runner ( 106 ) is arranged. Electric motor according to claim 1 or 2, characterized in that the spherical sliding body ( 138 ) rotationally fixed with respect to the stator ( 110 ) is arranged. Electric motor according to one of the preceding claims, characterized in that the rotor ( 106 ) one or more permanent magnets ( 116 ). Electric motor according to one of the preceding claims, characterized in that the rotor ( 106 ) a the stator ( 110 ) facing ball surface area ( 118 ) having. Electric motor according to one of the preceding Claims, characterized in that an air gap ( 128 ) between runners ( 106 ) and stator ( 110 ) by spaced spherical surface areas ( 118 . 130 ) is formed. Electric motor according to one of the preceding claims, characterized in that the central material-free region ( 150 ) is arranged around a lubrication hole or forms a lubrication hole. Electric motor according to one of the preceding claims, characterized in that the central material-free region ( 150 ) about an axis ( 122 ) of the runner ( 106 ) is formed. Electric motor according to one of the preceding claims, characterized in that the central material-free region ( 150 ) rotationally symmetric about an axis ( 122 ) is formed. Electric motor according to one of the preceding claims, characterized in that the bearing shell ( 140 ) a hollow cylindrical section ( 142 ) and a spherical section ( 148 ), which in the axial direction on the hollow cylindrical portion ( 142 ) follows. Electric motor according to claim 10, characterized in that the central material-free region ( 150 ) in the spherical section ( 148 ) is formed. Electric motor according to one of the preceding claims, characterized in that a diameter (M) of the central material-free region ( 150 ) is set in dependence on manufacturing tolerances. Electric motor according to one of the preceding claims, characterized in that a diameter (M) of the central material-free region ( 150 ) is equal to or greater than 0.6 times the diameter (d) of the spherical slider ( 138 ). Electric motor according to one of the preceding claims, characterized in that a diameter (M) of the central material-free spherical region ( 150 ) is smaller than the diameter (d) of the spherical body ( 138 ). Use of an electric motor ( 100 ) according to one of the preceding claims in a circulation pump.