FI113422B - Electric motor and procedure in an electric motor and the use of the same - Google Patents

Description

, 113422 Electric motor and method in electric motor and their use Elmotor och förfarande i en elmotor samt användningen av desamma

The invention relates to an asynchronous motor structure according to the preamble of claim 1, and in particular to a motor comprising a solid rotor means.

The invention also relates to a method according to the preamble of claim 11 for improving an asynchronous motor equipped with an array rotor means.

The invention further relates to a preferred use of the motor means and method of the invention.

Electric motors operating on an asynchronous machine principle have usually been machines that utilize so-called. levyroottoreita. The problems have been the vibrations already occurring at reasonable rotational speeds due to the rotor structure, in particular its poor bending and, in part, its poor torsional stiffness. The so-called disc rotor. the critical frequency is encountered at substantially low rotational speeds, which are too low, especially with respect to the normal elevated rotational speeds. The manufacture of the plate rotor structure also requires numerous work steps and specialized tools and machines, thus being slow and expensive to execute.

It has been well known in high speed rotating electric motors to use so - called. solid rotors, which achieve a much more robust and rigid structure than the plate rotor. However, in this case, the rotor resistance increases and the power factor of the machine drops substantially to typically be of the order of 0.6 to 0.7. The efficiency of such a rotor is also poor. However, single-piece, mostly smooth-peripheral solid-state rotors have been commonly used in short-circuit motors, where the speed range is substantially higher than conventional motors, up to 200,000 rpm. The problem with these, however, has been the aforementioned bad; efficiency and overheating, even when smaller ones are desired. conventional rotational speeds such as speeds of less than 20,000 rpm.

···. An example of an improved array rotor application is disclosed in British Patent No. 1,427,818. The rotor means according to the invention comprises a cylindrical, ...: low-carbon iron rotor shaft provided with a so-called rotor shaft.

2 113422 Copper cage winding to reduce rotor resistance. The axially extending portions of the cage winding shown, i.e. the copper rotor rods, are substantially hemispherical in shape with their widest portion flush with the peripheral surface of the rotor with a circular hemispherical peripheral surface disposed in a correspondingly shaped groove in the rotor.

Although the solution has gained the advantage of stiffening the rotor and reducing the resistance, it still has the problem of poor efficiency. These losses, in addition to poor efficiency, lead to significant in-use overheating. Attempts have been made to solve the problem of fever by means of various cooling arrangements, the power of which has further deteriorated the efficiency. In addition, a solution such as the one used uses a particularly small air gap (lines 81-82 p. 1), which causes significant additional losses. A major manufacturing problem has been the difficulty of fixing the axially, substantially wide, hemispherical copper sections of the cage coil in the rotor, especially at higher rotational speeds. Also, the disclosure does not disclose any suggestion or suggestion of how a rotor assembly such as that disclosed therein could be utilized in non-high speed motors. Such a solution is not e.g. For the reasons mentioned above, it became more common in electric motors.

The object of the present invention is to eliminate the drawbacks of the prior art and to provide a completely new type of electric motor structure comprising a shaped one. . : a stator means and a massive rotor means equipped with a new way: a cage winding means provided. The solution according to the invention provides an asynchronous electric motor structure whose efficiency and properties »· # ;;; are substantially superior to known solutions, and where no significant overheating problems such as those of known motors occur.

It is a further object of the invention to provide a structure and method for providing a motor means within a wide range of rotational speeds.

I «···. One object of the invention is to provide a solid rotor motor structure with a substantially low field weakening point. In this case, e.g. it is possible to load the machine at constant power over a • substantial rotational speed range.

It is a further object of the invention to provide a rotor means for a motor, which rotor means is easy to manufacture and the method utilizing which is thus easy and advantageous to implement.

It is a further object of the invention to provide a rotor means having a substantially low rotor resistance.

It is a further object of the invention to provide a motor structure whose speed of rotation does not substantially decrease as a result of a sudden increase in load.

A further object of the invention is to provide a rotor means which substantially prevents the generation of tangential currents.

It is a further object of the invention to provide a motor structure having a substantially sinusoidal distribution.

It is a further object of the invention to provide an engine structure comprising a solid rotor in which a substantially small air gap can be used without harm, thereby increasing the power factor.

It is an object of the invention to provide an engine structure having a size and weight: smaller than known asynchronous motor solutions of equivalent power.

A further object of the invention is to provide a solution in which a rotatable / ·,: object such as a fan, a tool such as a machining tool, a pump, etc.

can be fitted directly to the rotor shaft or its extension.

Yet another object of the invention is to provide a motor solution that can be used as a spindle motor for a robot or similar machine tool for triaxial movement.

: The invention is based on the surprising discovery that superior properties of previously known vt · · massive rotor motors can be achieved by providing a · · · · · · · · · · · · · · providing a solid rotor means and a co-operative stator means having a engine structure, in which the effect of the air gap permeation harmonics is substantially reduced compared to known solutions, which is particularly desirable when the rotor is massive.

More particularly, the structure of the invention is characterized by what is set forth in the appended claims 1 to 10 and in particular in the characterizing part of the independent claim 1. The method according to the invention is essentially characterized by what is stated in the appended claims 11 to 13, and in particular in the characterizing part of claim 11. A preferred use according to the invention is essentially characterized by what is stated in the appended claims 14 and 15, and in particular in the characterizing part of claim 14.

According to a preferred embodiment of the invention, the device comprises a substantially rigid, one-piece solid rotor means, with a circumferential surface suitably provided with cage winding means, preferably of copper or similar highly conductive material such as aluminum, brass or the like. The said axially extending portion of said cage winding means, i.e. the so-called. the shape of the rotor rod is provided substantially deep in relation to its width, thereby substantially reducing the influence of the air gap permeant on the stator means. In this case, a smaller air gap than the prior art can be used.

According to a preferred embodiment, the end or short-circuiting ring of the cage winding means is also substantially deep (high), thereby providing an advantage in the form of further reduced rotor resistance.

. The stator means are preferably formed of a plurality of parallel stator plates, between which there is suitable insulation. Their stator grooves in the receiving center opening of the rotor means are suitably shaped such that: they preferably form a stator tooth extending on each side of the groove towards the rotor means.

According to a preferred embodiment, the rotor means is provided by machining the peripheral shape of its body by turning it from a suitable steel blank, and then by, for example, milling or laser machining, to achieve a desired number of substantially axial, substantially narrow and deep grooves.

Preferably, the cage winding means inserted into the grooves is connected to the body material by electron beam welding (EB welding) or laser welding.

According to a preferred embodiment, the material inserted into the groove is connected, e.g. welded, to the rotor material only on one side. According to yet another alternative of 5 113422, a suitable air gap is left between said non-secured side and the rotor material. According to a particularly advantageous form of manufacturing, the so-called. a double metal plate, such as a FeCu plate, which is welded or otherwise attached to the rotor means only on the steel side,

According to the invention, the properties of the asynchronous electric motor are improved by a method in which the resistivity of a mass-rotary means rotatably mounted inside the stator means is reduced by the cage winding means provided in the rotor means. The effect of the permeation harmonics of the rotor means is reduced by providing substantially axially extending rotor rod portions of the cage coil means fitted to the rotor means in such a number and shape that the air gap distribution is substantially reminiscent of a sinusoidal dense step. The air gap flow is further preferably controlled by a suitably shaped dental stator groove shape provided in the groove means of the stator means.

Because of its wide constant power range, it is advantageous to apply the invention, for example, to the rotation of rotary tools in machine-tooling. According to a more specific embodiment, the motor structure according to the invention is utilized in: a three-axis space machine, such as a robot spindle; .> t as an engine.

The invention provides considerable advantages. The efficiency of the mass rotor motor is substantially improved over known solutions; when the problem of engine overheating is greatly reduced. The invention reduces the size and weight of the engine as compared to known engines of similar performance. The engine of the invention provides a substantially uniform maximum power over a substantially wide rotational speed range, such as in the range of 6,000 to 30,000 rpm or 1,000 to 5,000 rpm, i.e..

. ·. in the minimum / maximum speed range of about 1/5 or eg 1/8. In addition, the speed of rotation of the engine structure according to the invention decreases substantially with a sudden increase in load, e.g. as a result, known solutions, .. · reduced need for speed sensing and control. No in the engine: there is also a significant amount of leftovers. The engine structure and method of the invention are applicable to a wide variety of applications due to their good features such as small size and weight, wide rotational speed range and smooth power curve, since the same engine is applicable to a variety of applications. The manufacture of the motor means according to the invention is easier to carry out than the known solutions, but still more durable and e.g. more reliable construction with respect to rotor rod stability.

The invention and other objects and advantages thereof will now be described, by way of example, with reference to the accompanying drawings, in which like reference numerals in the various figures refer to like features. It is to be understood that the following exemplary disclosure is not intended to limit the invention to the specific forms set forth herein, but on the contrary is intended to encompass all modifications, equivalents, and variations within the spirit and scope of the invention as defined in the appended claims. It is further noted in this connection that the term stator means refers to any stator solution in which it is possible to obtain a stator groove design in accordance with one aspect of the invention. In addition, the term rotor rod hereinafter refers to a portion of the cage winding means extending substantially axially between the short-circuiting ring means.

Figures 1a and 1b show a simplified schematic side and sectional view of a rotor means of an engine structure according to the present invention.

; Fig. 2 shows a stator plate means according to the invention.

Figures 3a, 3b and 3c are schematic representations of prior art and stator means of the motor structure of the invention.

Figures 4a, 4b and 4c are schematic views of further embodiments of the invention.

Figures 5a and 5b show an experimental arrangement according to the invention, Figures 5c and 5d being tabular representations of the test results achieved.

Fig. 6 shows yet another embodiment of the rotor means.

I ·

Figure 7 is a schematic view of a preferred embodiment of the invention.

Fig. 1a shows one massive rotor means 10 obtained from a continuous steel blank of the asynchronous electric motor structure 7 113422 according to the invention. Its cross-section along line A-A is shown in Fig. 1b. As can be seen from the figures, the peripheral circumference 12 of the rotor means 10 is provided with a groove in which the substantially axially extending portions of the cage coil means 16, i.e. the shape of the rotor grooves 14 receiving the rotor rods 15, are substantially deep relative to their width. Particularly preferred ratios of rotor rod width / depth are in the range of 1/3 to 1/10. It should be noted that although the bars in the figures always have a substantially rectangular cross-section, they may, if necessary, also deviate therefrom, e.g. wedge-shaped, triangular, or partially barrel-shaped or concave, without departing from the general idea of the invention.

In the example of Figures 1a and 1b, there are 28 grooves, the groove 14 having a depth of about 10 mm and a width of about 3 mm. The test rotor made of Fe 52 structural steel was approximately 160 mm in length and approx.

87.5 mm.

Further, Figure 1b shows copper short-circuiting rings 18 at the ends of the cage winding means 16, which were about 30 mm deep (high).

1a and b, a copper cage winding means 16 connected to the rotor by electron beam welding, ·, · was used. Alternatively '· * could have been used, for example, an aluminum cage winding device which could have been dropped e.g. effects of centrifugal forces acting on the rotor due to the lighter specific gravity of aluminum. The rotor rods 15 provide good axial electrical conductivity, so that the motor structure gives high torque in this respect with minimal leaving. Thus, the motor losses are reduced v; still, especially at high power.

* *

Further, the substantially axially extending rods i · · * 15 of the rotor of Fig. 1b are slightly wound in a spiral shape, i.e. at an angle with the axial direction, such that the other end of each winding bar 15 is offset by one slot. However, this is only a further embodiment and is by no means necessary for carrying out the invention.

The preferred rotation means 113422 sec rotor means 10 shown in Fig. 1b does not substantially heat the stator means, since the effect of the permeation harmonic of the cage winding 16 provided on the substantially narrow rotor grooves on the grooves 21 of the stator means 20 or or rods. This is a consequence of e.g. that substantially perm-harmonic harmonics in the prior art would cause iron loss in stator teeth 22 shaped as shown in Figure 2c. However, the losses can be minimized by a rotor structure such as the invention.

The substantially narrow rotor grooves also provide an advantage in the distribution of the air gap. The ideal distribution distribution would be completely sinusoidal, but could not be achieved with known cage winding solutions. However, the use of a plurality of grooves, which are substantially densely spaced and substantially narrow in the tangential direction, achieves a very large number of substantially small steps in the flow curve distribution, whereby the shape of the flight curve is very close to the ideal sinusoidal shape.

Figure 2 shows a preferred form of stator plate 20 showing stator groove means 21 and formations 22. In this connection, it will be noted that, although not illustrated, one skilled in the art will recognize that the motor structure of the invention 1a and b>; In addition, it is clear that the motor structure may be provided with suitable cooling means, such as duct and conductor installations required for air or liquid cooling t ·.

»·

Fig. 3a is an enlarged sub-view of a prior art groove shape and Fig. 3b is a corresponding enlarged sub-view of one of the tooth means 22 according to the invention: It is noted that the figures. 3a and b are not on a precise scale with respect to each other. The graph of Fig. 3c · '·' shows the difference between the prior art and the distribution of the flow rate provided by the stator groove T according to the invention in the ideal idle state of the machine, curve a) corresponding to known, i.e., Fig. 3a and curve b); 3b.

Figure 3a thus shows a shape of a stator groove 21 'utilized in the prior art. The distribution of the flux density obtained therefrom in the electronic airborne 9 113422

Where ls is depicted by lines 26 '.

Figure 3b shows the shape of the stator groove 21 used in the invention. Each side of the stator groove 21 has a tooth 22 extending from the stator plate 20 to the rotor opening 24, the effects of which on the flux density distribution are clearly discernible by the flow lines 26. In the case of Fig. 3b, the air gap can be further divided, as shown in the figure, into an electric air gap ls between the rotor and stator and a lesser physical air gap between the rotor and the tooth tip. In particular, tooth 22 does not need to enlarge the electric air gap ls in order to obtain a smooth flux on the peripheral surface 12 of the rotor 10. A corresponding effect is also achieved with tooth shapes other than Figure 3c and it is essential that the stator track edges have properly shaped on the rotor surface so that the electrical air gap does not need to be increased too much.

As can be seen from the graph of Fig. 3c, the flow distribution (b) provided by the dental shaped stator groove means (tooth) 22 is substantially smoother than that achieved by the known solution (a). 3b, and, more specifically, its permeation harmonic, does not heat the rotor 10 at all, i.e., the effects of the permeation harmonics are minimized.

Fig. 4a is a schematic cross-sectional view of a further preferred embodiment of a rotor means according to which an axially extending rotor bar 15 of a cage winding device for insertion into a groove is secured only; one side 32 to the groove 14. Advantageously, the attachment can be effected, for example, by electron beam welding (EB welding) or laser welding. This solution provides an advantage e.g. the amount of welding required.

»* 'I ft:: In addition, although not always necessary, can be between groove 14 and leg 15. ·. it may be advantageous to leave even a small air gap 35 as shown in Figure 4a. The air gap may * »··. preferably in the order of 0.1 to 2 mm.

According to an alternative shown in Figures 4b and c, a suitable so-called spacing means 14 is inserted into the groove means 14. a double metal plate which may preferably be an iron-copper plate (FeCu) as shown in Figure 4b. Such a double metal plate, in which various materials, i.e. copper and steel 15 'and 15 "may be joined together, e.g. by blast welding, is known to the person skilled in the art and commercially available. The rotor means according to Fig. 4b is particularly easy to manufacture or otherwise connect only one side of its steel portion to the steel rotor at the position indicated by the arrow, i.e., two flat joint surfaces of substantially similar material can be connected to each other by simple and inexpensive jointing methods. are not as accurate as the situation with eg copper-iron joints.

Figure 4c is a side view of the situation of Figure 4b on a reduced scale. The end ring 18 is also made of a FeCu sheet, respectively. Hereby, the steel portions of the end plate 18 can preferably be welded with an arrow to the rotating rib material 10 and the copper portions can be soldered or welded to the copper of the rotor bars.

In addition to manufacturing advantages such as ease of attachment, reduced need for welding, and faster execution, only one side-mounted rotor-cutting tool 15 further prevents the formation of tangential currents, whereby the characteristics of the array rotor 10 resemble substantially discrete and magnetic When the general objective is generally considered e.g. the power; running axially in the rotor 10, i.e., in the direction of the rotor rod 15, such a rotor arrangement further improves substantially those achievable by the invention; engine characteristics, in particular engine power factor.

* 1 · • »

Figure 5a and the table in Figure 5b show one experimental arrangement used to test a 12 kW, 300 Hz massive rotor motor according to the invention. The equipment shown in dashed line in Fig. 5a has been replaced in some tests by a so-called "fit" between motor 1 and power supply. a static converter, or an inverter 40. Such inverter means are known per se and commercially available.

The line diagrams in Figures 5c and 5d show test results of a comparison in which T was compared with three different massive rotor structures (see 5a and 5b) with different power supplies. The rotor structures used were (curve numbers): smooth rotor; · /. (1 and 4), a grooved rotor (2 and 5) and a rotor (3 and 6) provided with a cage winding according to the invention. The rotors corresponded to each other except for the groove (2 and 4) provided therein and the cage winding means (3 and 6) of the invention.

"113422 11

Figure 5c shows a comparison of the torque characteristics of the motor with a test motor of the type described, equipped with a 300 Hz inverter (1-3) and a sinusoidal supply (4-6) with rotational speeds ranging from about 280-300 RPM. As can be seen from the graph, the grooved rotor (2,5) gives a better torque curve by correspondingly leaving out what can be achieved with the smooth rotor (1,3). However, the motor with the copper cage winding device (3,6) according to the invention clearly achieved the best results. The nominal feed rates for the blue feed were 3.5% for smooth rotor, 2.2% for slotted and 0.3% for cage winding.

The curves in Fig. 5d illustrate the efficiencies achieved with respect to the output power at a voltage of 400 V and a frequency of 300 Hz. As can be seen, the efficiency of different rotors is approximately the same up to 5 kW. Thereafter, even low losses of the rotors become essential, and the efficiency of the motor equipped with the cage winding rotor according to the invention can be considered to be by far the best and also gives the widest substantially uniform power in both feed modes.

Figure 6 shows an additional embodiment. Herein, the rotor rod means 15 provided in the rotor means 10 are in an inclined position, i.e. at an angle relative to the radial direction. Further, the grooves 14 are preferably closed by welding on the peripheral surface 13. The rotor slot, as shown. the kennel does not produce any permance harmonics at all. It can accommodate • a substantial amount of copper or the like, which has a particularly good stability in the groove 14, e.g. due to the tilt, but also due to the closing of the groove from above. Such a structure is considered to be advantageous in large motors, mainly rotating in one direction, but the possibilities for utilization thereof are not limited, but can be successfully used also in smaller and / or bi-directional motors.

According to an advantageous embodiment shown in Fig. 7, the motor structure 1, comprising a rotor means 10 according to the invention and a suitable stator means 20, is arranged as a drive device 1t for the robot means 40 or the like, such as a spindle motor 1. Hereby, the arrangement is preferably such that the motor 1 is adapted to drive or rotate a machining spindle 42 fitted to the robot 40 or the like, and thus a rotary tool or the like.

12 113422

The motor structure according to the invention is particularly suitable for machining applications, since machining machine motors are usually required to have uniform properties, such as power and torque, throughout the speed and power range. Typically, for example, rotating speeds used in robotic rotary tools range from 10,000 to 20,000 rpm, with power requirements typically in the range of <20 kW. Thus, the engine structure according to the invention, which is essentially light in weight, small in size and small in size, is particularly suitable for use in robots or the like where the motor needs to be moved in three-axis space and the power requirement increases rapidly when the blade is suddenly pressed onto the workpiece.

The invention thus provides an apparatus and method for achieving a substantial improvement in the properties of massive rotor motors which can be applied particularly well in a variety of applications requiring medium speed and high speed motors. However, the structure according to the invention is small and light in weight, simple in construction, easy to manufacture and therefore economically advantageous, and reliable in operation.

It should be noted that the foregoing examples of embodiments of the invention are not intended to limit the scope of the invention as claimed. With the foregoing description and drawings, it will be apparent to one skilled in the art to use the method and apparatus of the invention in a wide variety of applications such as various fan, blower and pump motors and the like, various, fixed and movable applications, such as: drives and electric motors for ships or trains and so on.

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Claims (15)

An asynchronous electric motor structure comprising stator means (20), a cylindrical rotor means arranged coaxially within the stator means, wherein the rotor means is a substantially rigid mass rotor means (10), at which outer periphery (12), a plurality of blocking means (14) is provided in a substantially axial direction, and a cage winding means (16) located in the saving means (14) of a material which conducts electricity with substantially higher electrical conductivity than the rotor means material, characterized in that a plurality of rotor rod means (15) contained in said cage winding means (16); (15) with substantially axial extension in the vicinity of said outer periphery (12) is substantially narrow in proportion to its height. 2. Engine according to claim 1, characterized in that a plurality of designs are arranged at the periphery of a hub cavity (24) in the stator means (20) which: receives the rotor means (10). stator locking means (21) for controlling the flow in the air gap. Motor according to claim 2, characterized in that said stator means comprise a plurality of between-V: insulated stator blades (20) positioned parallel in the axial direction of the motor, which have projections (22) on each side of each stator lock (21). extending toward the rotor means, which projections are adapted to control the flow in the air gap in the direction of the rotor means such that a substantially sinusoidal flow distribution (26) is obtained over the entire outer periphery (12) of the rotor means (10). 113422 Engine construction according to any of the preceding claims, characterized in that at least a part of the cage winding means (16) of at least one part (32) of the cage winding means (16) of the cage winding means is fixed to a side surface (31) of a receiving latch (14). in the rotor means (10), whereby the other side surface (34) of the rotor rod means (15) is not attached. Engine structure according to any of the preceding claims, characterized in that the rotor rod means (15) to be arranged in a lock in the rotor means comprise at least two parts (15 ', 15 "), part of which (15') consists of a material with greater electrical conductivity than the rotor means and another part (15 ") of a material of substantially the same kind as the rotor means. Motor structure according to claim 4 or 5, characterized in that there is an air gap (35) between said fixed side surface (34) of the rotor rod means (15) and the corresponding side surface (33) of the receiving latch in the rotor means (10). : 7. Engine structure according to any one of the preceding claims::: The claims, characterized in that said rotor rod means · / ·: (15) are arranged in inclined position in relation to the radial direction in correspondingly inclined ratchets (14) in: V rotor means (10). 8. Engine design according to any of the foregoing; The claims, characterized in that the rotor rod means (15) at the periphery (12) of the rotor means (10) extend at an angle relative to the axial direction. 113422 Motor design according to any of the preceding claims, characterized in that the arrangement further comprises a static frequency converter or inverter means (40) arranged between a power source and the motor (1). Engine design according to any of the preceding claims, characterized in that a short-circuiting ring (18) present at one end of the rotor means (10) comprises at least two parts of different materials. 11. A method of improving an asynchronous electric motor, wherein a method of using a cage winding agent obtained in a rotor means reduces the resistivity of a rotary mass rotor installed installed in stator means, the method being characterized in that it further comprises reducing the permeanharmonic action of the rotor means (10) by forming the rotor rod means (15) of the bur winding means (16), such as. fitted into the rotor means, in such a form, that the distribution of the air gap flow to its shape consists of a substantially sinusoidal staircase curve in close steps. * · I · Method according to claim 11, characterized in that: T: further comprising a step of further controlling the air gap flow by obtaining a suitably formed toothed form (22) of detent means (21) in the stator means (20), the flow distribution (26) is substantially sinusoidal about the entire periphery (12) of the rotor. A method according to claim 11 or 12, characterized in that it further comprises essentially separating the electrical and magnetic circuit from each other by providing a discontinuity point between at least one side (34) of said portions (16) with axial extension and one side (33) of a spar (14) in the rotor means (10). Use of a device according to any one of claims 1 to 10 or to a method according to any of claims 11 13, characterized in that it is applied in a machine tool drive (40) when rotating a rotary tool (42). Use according to claim 14, characterized in that it is used as a spindle motor in a robot (40) or the corresponding processing device adapted for movement in three-dimensional space. • · • * • · «·» · i *