WO1992017932A1

WO1992017932A1 - Liquid-cooled electric motor having pipe for cooling liquid inside motor housing

Info

Publication number: WO1992017932A1
Application number: PCT/JP1992/000382
Authority: WO
Inventors: Kosei Nakamura; Yukio Katsuzawa; Michi Masuya; Yasuyuki Nakazawa
Original assignee: Fanuc Ltd
Priority date: 1991-03-29
Filing date: 1992-03-27
Publication date: 1992-10-15
Also published as: JPH04304145A; JP2661805B2

Abstract

A housing is made up of a thermally highly conductive casing (20) surrounding the outer periphery of a stator (16) of a multiphase induction motor, and front and rear frange (22, 24) for supporting bearings, which are coupled in a sealing way to the front and rear of the casing (20) respectively. A main pipe (60) and auxiliary pipes (40, 80) for a cooling liquid, through which cooling liquid is forced to flow are provided inside the housing. Thereby, the two kinds of heats, which are generated by the copper losses in the stator (16) and a rotor (12), and by the rotation in the bearings (14a, 14b) for an output shaft (10) of the rotor (12) are taken away.

Description

Description A coolant line was provided inside the motor casing.

Liquid-cooled electric motor Technical field

The present invention relates to a liquid-cooled electric motor, and in particular, to a casing having good thermal conductivity and a front and rear flare for forming a flow pipe for a coolant to form a jacket of the motor. Highly efficient cooling motor provided inside the nozzle, and can be effectively applied as an electric motor that forms the spindle drive source mainly in machine tools such as machining centers. Related to liquid-cooled electric motors. '

Conventional technology

The spindle drive in machine tools, especially in labor-saving machine tools such as machining centers, is a liquid-cooled motor with high cooling efficiency due to its continuous operation, and also induction. It is well known that liquid-cooled electric motors of the form are used. In recent years, induction-type electric motors, particularly three-phase induction motors used as main shaft drive sources for machine tools, have a primary winding on which a primary current is supplied to the stator side. A cage-type or cap-type rotor composed of a secondary current winding circuit is formed, and the primary winding is switched or changed between a Y-connection and a delta-connection. By controlling the slip ratio between the motor and rotor (S = n-ΤΊ '/ n), a large torque is generated at a low speed even under the same current for a single induction motor. It is configured to be possible.

However, in order to obtain a high torque and a low rotational speed, When switching is performed (switching from the delta winding method to the Y winding method), the resistance between the terminals of the primary winding of the three-phase induction motor is reduced to about 3 before the switching. It shows twice the resistance, and therefore, when a primary current of the same current value flows, the copper loss heat generated in the primary winding also triples. On the other hand, in order to provide a large output torque in this kind of induction motor, the structure of the aluminum cage rotor or the aluminum cap rotor is made larger. Therefore, a large secondary current flows in proportion to the slip "S". Therefore, even if the electrical resistance of the aluminum material forming the rotor is the same, the copper loss can be reduced by the secondary current. The result is an increase in proportion to the square. Therefore, as a result, if a low-speed and large torque is generated by switching from delta connection to で connection in the winding switching method, the motor status and motor The amount of heat generated from this will increase.

With the electric motor for driving the spindle of the machine tool, if the spindle of the machine tool undergoes thermal deformation due to heat transfer, which adversely affects the machining accuracy, heat generation on the drive motor side is suppressed as much as possible. In addition, it is an essential condition to suppress heat transfer from the motor side to the machine spindle. Therefore, the cooling of this type of induction-type electric motor for driving a spindle by using a liquid cooling system instead of an air cooling system to improve the cooling efficiency has already been provided. In other words, International Patent Application No. PCTZJP85 / 0000633 filed by the present application discloses that a coolant circulation path that penetrates in the axial direction into a stator core of an AC electric motor. The end plate is pressed against the front and rear ends of the stator core, fastened with bolt screws, and impregnated with resin material between the stator cores. Structured to cover the wall of the circuit and formed inside the stator core After preventing the liquid from leaking in the coolant passage, the coolant is caused to flow through such a coolant passage to remove heat from the stator core. Disclosed. However, in the liquid cooling system disclosed in the international patent application PCT / JP85 / 00006334, the copper cooling in the stay and the rotor causes the liquid cooling method. Although it is possible to remove the generated heat, it is due to the rotational friction from the rotating bearings that support the motor output shafts installed before and after both end faces of the stator. It is impossible to remove the generated heat.It is impossible to provide a coolant cooling passage in the lamination end for a long time from the viewpoint of preventing leakage. It is difficult to expect cooling. For example, the thermal coating degrades the resin coating due to heat cycling and lacks reliability in preventing coolant leakage.

On the other hand, hoops are arranged in the shape of a lace around the outer periphery of the status core. There is also a liquid cooling motor in which the cooling fluid flows through the die to remove the heat generated from the stator and the mouth.However, in this method, The heat generated from the rotating bearings supporting the motor output shafts installed before and after the end of the heater is placed in the same way as the one with the coolant passage inside the data core. Impossible to do

Φ Since the heat generated from the rotating bearing during high-speed rotation cannot be ignored, it is impossible to remove the heat generated from this kind of rotating bearing and cool it. In this case, as described above, heat deformation occurs due to heat transfer on the main shaft of the machining machine, which adversely affects the accuracy of machining. Is not possible to apply to Disclosure of the invention

Therefore, an object of the present invention is to take advantage of the high cooling rate of the liquid cooling system, and not only to remove the generated heat in the stator rotor but also to the rotary bearing. In particular, an object of the present invention is to provide an induction type electric motor which is provided with a cooling means capable of removing and cooling heat generated during high-speed rotation, and which can be applied to a spindle drive of a machine tool.

Another object of the present invention is to provide a cooling system in which a cooling liquid passage is provided inside a stator core employed in a conventional liquid cooling motor to prevent leakage in a processing process of the stator. In view of the fact that complicated processes such as erosion of the resin material are involved in forming the coating, an improved cooling means using liquid cooling without such a complicated processing step is required. Liquid provided

? It is to provide a ^ -type electric motor.

According to the present invention, there is provided a case made of aluminum having good thermal conductivity surrounding an outer peripheral portion of a steer core of a polyphase induction motor, and the case made of aluminum is provided. A flange for supporting the bearing, which is sealed and tightly bonded to the front and rear end surfaces of the ring, is provided.The cooling liquid is placed inside the casing means consisting of the casing and the front and rear flanges. To remove the copper loss heat of the motor stator and the rotor, and to remove the rotational heat of the bearing, and to improve the heat removal efficiency even at high torque and low speed rotation. This constituted a liquid-cooled motor with a high liquid-cooling mechanism.

That is, according to the present invention, in a liquid-cooled motor that cools generated heat with a cooling liquid, the outer periphery of a stator provided around a rotor having an output shaft is surrounded. A plurality of coolant main pipes which are distributed at a plurality of locations on the periphery of a tubular cylinder having good heat conductivity provided in the housing and penetrate in the axial direction; The coolant main pipe of the cylindrical casing is provided on both front and rear flanges which are sealed and adhered to the front and rear end surfaces of the cylindrical casing and support the bearing of the output shaft. A plurality of coolants are formed as fluid passages communicating with the coolant, and are provided for connecting the plurality of coolant main pipes and for introducing and discharging the coolant from outside the motor machine. A liquid-cooled electric motor that is provided with a sub-pipe and heats and cools with a cooling fluid that flows inside a jacket consisting of a cylindrical casing and front and rear flanges. It provides data. BRIEF DESCRIPTION OF THE FIGURES

The above and other objects, features, and advantages of the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing a structure of one embodiment of a liquid cooling motor having a liquid cooling pipe according to the present invention inside a jacket,

FIG. 2 is a cross-sectional view of the status portion taken along the line II-Π shown in FIG.

FIG. 3A is a cross-sectional view showing the passage of the coolant formed in the rear flange by the H A -ΠΙ line shown in FIG. 1,

FIG. 3B is an end view showing the coolant passage formed in the rear flange along the line MB-HIB in FIG. 1 and a sealing mechanism,

FIG. 4A is an end view showing the coolant passage formed in the front flange and the sealing mechanism as viewed from the line IV A—IV A in FIG. 1, and FIG. 4B. FIG. 1 is an end view taken along the line IVB—IVB in FIG. 1, and FIG. 5 is a liquid cooling motor according to the embodiment of the present invention shown in FIG. Schematic diagram of the coolant circuit, which takes out and illustrates the coolant flow path of the

FIG. 6 is a cross-sectional view taken along lines IA-VIA and VIB-VIB of FIGS. 3B and 4B.

FIG. 7A is a graph showing how the cooling efficiency of a liquid-cooled electric motor according to the present invention is improved over a conventional air-cooled electric motor,

FIG. 7B is a schematic view of an electric motor showing a measurement position where the data of FIG. 7A is obtained. BEST MODE FOR CARRYING OUT THE INVENTION

First, referring to FIG. 1, the liquid-cooled electric motor according to the present invention includes a rotor 12 having an output shaft 10, and the output shaft 10 includes front and rear rotating bearings 14. It is supported by a and 14b, and is provided as a motor element rotatable around the axis of the output shaft 10 together with the rotor 12 together. As is well known, a stator 16 is provided as a motor stationary element around the D—taco core 12 a of the rotor 12 through an air gap, as is well known. The stator 16 is mounted on a stator core 18a formed by laminating magnetic material laminates, and a winding groove formed on the stator core 18a. And the primary winding 18b for excitation.

The liquid-cooled electric motor further includes a cylindrical casing 20 surrounding the outer periphery of the above-mentioned stator 16 and a cylindrical casing 20. A front flange 22 and a rear flange 2 are hermetically bonded to the front and rear ends. Here, the front The flange 22 is formed as a cap-shaped element, has a bearing hole in the center for supporting the front rotary bearing 14a, and the rear flange 24 similarly has a key. These casings 20 and the front and rear flanges are formed as cap-shaped elements and have a bearing hole in the center to support the rear rotating bearing 1 ". 22 and 2 form a casing element of the motor, and include therein a coolant pipe for flowing a coolant of a liquid cooling means to be described later, and the stator 16 and π — Since it acts to remove heat from the metal 12, it is formed of a metal material having good thermal conductivity, that is, a suitable material, namely, a luminous material or a luminous alloy material. In this case, it is possible to manufacture the casing 20 and the flanges 22 and 24 by the machine addition method, but a more effective method is possible. as The motor can be manufactured by molding and molding, etc. The exciting current is applied to the primary winding 18b of the stator 16 at the rear of the motor. Terminal box 26 for supply is installed

In the liquid-cooled electric motor shown in FIG. 1, a cooling liquid introduced from outside the motor as a liquid cooling means is formed inside the rear flange 24. The cooling liquid sub-pipe introduced from the liquid sub-pipe 40 and formed in the front flange 22 via the cooling liquid main pipe 6 形成 formed in the cylindrical casing 20 To the channel 80, pass through the coolant sub-line 80 in the front flange 22, and then again through the coolant main line 60 of the cylindrical casing 20. After passing through the circulation cycle returning to the coolant sub-line 40 of the rear flange 24, such a circulation cycle is performed several times before the rear Drain the motor from the cooling liquid sub-line 40 of the flange 24 and return to the cooling liquid supply source It has a configuration to make it work. Then, the coolant is supplied to these cylindrical casings.

— While flowing through the ring 20 and the front and rear flanges 22 and 24, the copper loss heat generated in the rotor 12 and the stator 16 is removed and cooled. In addition, the front and rear flanges 22 and 24 have a function of removing heat generated during high-speed rotation of the rotary bearings 14a and 14b and cooling them.

Referring now to FIG. 2 together with FIG. 1, the cylindrical casing 20 has a substantially rectangular cylindrical casing with four chamfered corners. An outer shell structure is provided so as to surround the stator core 18a of the stator 16 so as to surround it. Cooling lines 62a, 62b, 6a having four sets of seed shapes (seeds) that form cooling liquid main lines 60 at the four corners. , '64 b, 66 a, 66 b, 68 a, 68 b are formed. All of these four sets of coolant pipes 62 a to 68 b are formed so as to penetrate parallel to the motor axis direction, and in this embodiment, are point-symmetric with respect to the center of the motor. There are four sets. Screw holes for connecting the front and rear flanges 22 and 24 described later with port screws between the coolant lines of each set, for example, the coolant lines 62a and 62b. 70 is formed. The coolant lines 62-68 are drilled or formed during the machining of the cylindrical casing 20 so that the coolant can flow smoothly. The wall is formed smoothly. In addition, the front and rear end surfaces of the casing 2D are finished to have a surface roughness of about R max = 1 micron, and the front and rear flanges 22 and 24 and the 0 ring are interposed. In this way, the cooling liquid is prevented from leaking from the poor adhesion of the rings at these end faces by improving the close contact and bonding. Surface roughness described above To achieve a high-precision surface with a high degree of precision, turning using a well-known round piece byte or turning using a bailing tool can be realized. Confirmed. The structure for enhancing the tight bonding between the front and rear flanges 22 and 24 and the end surface of the cylindrical casing 20 is described below. Attach a sealing ring to 2 24, and connect both flanges 2 2, 2 4 to the cylindrical casing by using a port screw 100 (see Fig. 1). By fastening at 20, complete sealing and adhesion can be obtained, and it is possible to prevent the cooling liquid.

Referring to FIG. 3A and FIG. 3B, the coolant line constituting the coolant sub line 40 formed in the rear flange 24 that supports the rear rotary bearing 14 b is shown. And a sealing 0-ring 72 formed on the end face.

In this embodiment, the rear flange 24 is provided with a coolant inlet 41 and an outlet 42 for discharging the coolant after passing through the coolant channel of the jacket. By forming a plurality of coolant channels in which the coolant introduced from 41 flows, the above-described coolant channel 40 is configured. That is, the coolant sub-line 40 is constituted by the coolant lines 44 to 54, and the coolant lines 46, 49, 52 are connected to the rear flange 24. It is formed as a comparatively long pipe extending inside along the side, and is cut from the side of the rear flange 24 with a tool such as a drill, and closed. The end is closed by screwing a pipe screw 55. The coolant lines 44, 45, 47, 48, 50, 51, 53, 54, etc. formed at the four corners are cut in the thickness direction of the rear flange 24. Relatively short pipeline installed It is.

On the other hand, the end face where the rear flange 24 is tightly attached to the cylindrical casing 20, that is, the seed shape is formed at the four corners on the surface corresponding to the paper surface of FIG. 3B. Recesses 56 are formed around the corresponding pipelines 44, 45, 47, 48, 50, 51, 53, 54, at the edges of the recesses 56. Along with the sealing ring 72 described above. FIG. 6 is a cross-sectional view taken along the line IVA-IV in FIG. 3 showing the relationship between the ω position 56 and the 0-ring 72 formed around the above-mentioned coolant line. When the 0 ring 72 is pressed against the end face of the cylindrical casing 20, the sealing function is exerted, and the cooling liquid from each cooling pipe is displayed. This prevents leaks from leaking. The machining of the recesses 56 is as simple as the surface roughness R max = 1 micron by flattening using end mill, a well-known machining tool. It is possible to form in.

Also, a hole 57 is formed for passing the bolt screw 100 (FIG. 1) when the rear flange 24 is fastened to the cylindrical casing 20. ing. It goes without saying that a bearing hole 58 for supporting the rear rotary bearing 14b is formed in the center of the rear flange 24.

Similarly, FIGS. 4A and 4B illustrate a plurality of coolant lines 81-97 that form a coolant sub-line 80 formed in the front flange 22. The closed ends of the pipelines 82, 83, 86, 87, 91, 92, 95, 96, etc. are closed with pipe threads 55 similar to those described above. Also, as clearly shown in FIG. 4A in particular, the end face of the cylindrical casing 20 which abuts against the front end face is provided with the aforementioned rear flange. A recess 96 similar to the recess 56 of the die 24 is cut and formed so as to surround the corresponding coolant line, and the coolant 96 is prevented from leaking into the recess 96. A sealing ring 72 is provided.

Of course, the front flange 22 is also provided with a bearing hole 98 for supporting the rotary bearing 14a, and a bolt for fastening to the casing 20. It goes without saying that the through hole 97 through which the same 100 is passed is formed.

The cooling liquid main line 60 of the cylindrical casing 20 having the above configuration and the cooling liquid sub-lines 40 and 80 of the front and rear flanges 22 and 24 are provided. Therefore, in the liquid-cooled electric motor of this embodiment, the coolant is introduced from the outside, and the cylindrical casing 20 and the front and rear flanges 22, 2, which are the outer casing elements, are used. 4 to flow through the pipeline built in, to remove the copper loss heat of the rotor 12 and the stator 16 and the frictional heat generated by the rotary bearings 14a and 14b during rotation. In this way, the motor body can be cooled and the heat transfer to the machine tool, including the spindle, can be prevented even when it is used directly as the spindle drive source for the machine tool. This can prevent thermal deformation of the main spindle etc. on the machine tool side.

FIG. 5 is a coolant circuit diagram taken out and shown in order to make it easy to understand only the flow path of the coolant in the liquid-cooled electric motor shown in FIG. . From the circuit diagram of the cooling liquid shown in Fig. 5, the cooling liquid introduced from the inlet 41 circulates sequentially and cyclically in the motor body, and finally the outlet 4 You can see how it is discharged from 2. That is, the coolant sub-channels 40, 80 formed in the front and rear flanges 22, 24 are cooling formed in the four corners of the cylindrical casing 20. Connect the liquid main line 60 and It cools the flanges 22 and 24 and removes the heat generated from the rotating bearings.

FIG. 7A is a Darraf diagram showing the effect of cooling the liquid-cooled electric motor according to the present embodiment in comparison with a conventional air-cooled electric motor. FIG. 7B shows the temperature detection position of the motor body. The temperature detection indicates the case where the detection is performed when the motor is operated at the output rotation speed of the motor of 8 and OOOrpm in both the conventional and the present invention. One point of the casing suitable for detecting the heat loss effect of the heat loss of the stator and the rotor, and also suitable for detecting the heat loss effect of the generated heat of the rotary bearing. The measurement result of one of the front flanges and the selected temperature detection point is displayed in a graph.

As is evident from the graph, the motor used in the conventional air-cooled electric motor had a 7.5 kW output, and the temperature rise during operation was remarkable with time. However, in the liquid-cooled electric motor according to the present invention, the temperature rise during operation at an output of 18.5 Kw is much lower than the conventional temperature curve, and the cooling effect is remarkable. It can be understood that The change in temperature of the coolant is also shown for reference.o

In the above-described embodiment, the coolant is introduced from the rear flange 24 and the coolant is discharged from the rear flange 24 again after circulating through the internal pipe of the motor casing. Although the configuration is adopted, as another embodiment, the coolant may be introduced from an appropriate position of the front flange 22 or the cylindrical casing 20 as necessary. Needless to say, it's okay.

As is clear from the above description, according to the present invention, the liquid cooling type In an electric motor, the cylindrical casing forming the outer casing of the motor body and the front and rear flanges are hermetically sealed and joined in the axial direction, and these casings are connected to each other. Since the cooling fluid conduit is formed inside the flange and flange, the heat generated by the motor, especially copper loss due to the primary current supplied to the primary winding of the stator section In addition, the rotary bearings, which are supported by the front and rear flanges, reduce the heat generated by secondary current in the rotor and the frictional heat generated with the high-speed tillage at a low cooling rate. Therefore, even if this type of induction motor is applied to the drive source of the spindle of a machine tool, it can be applied without causing thermal deformation due to heat transfer to the spindle. In addition, since the cylindrical casing and the front and rear flanges are made of a thermally conductive aluminum or aluminum alloy material, it helps to increase the efficiency of heat removal. It is.

Also, in the coolant line, the joint between the casing and the front and rear flanges is an effective sealing and sealing mechanism despite the simple structure using a ring. As a result, liquid leakage can be reliably prevented, and the sealing ring can be easily replaced if necessary.

Claims

The scope of the claims

1. The liquid-cooled electric mod

A rotor with a rotary output shaft,

A stator provided around the rotor,

A thermally conductive cylindrical casing provided so as to surround the outer periphery of the stator; and

Front and rear flanges which are sealed and adhered to front and rear end surfaces of the cylindrical casing, and which hold the bearing of the rotary output shaft;

Liquid cooling means for cooling the heat generated by the motor with a cooling liquid, wherein the liquid cooling means comprises:

A plurality of coolant main pipes which are distributed and arranged at a plurality of peripheral edges of the stator and penetrate in the axial direction;

The plurality of coolant main pipes are formed in the front and rear flanges, respectively, and are provided as liquid passages communicating with the plurality of coolant main pipes of the cylindrical casing. And a plurality of coolant sub-channels provided for the introduction and discharge of coolant from outside the motor machine.

A cooling effect is obtained by a cooling fluid flowing inside a motor casing comprising the cylindrical casing and the front and rear flanges. Liquid-cooled electric motor.

2. The cylindrical casing is made of a rectangular cylindrical casing having four corners, and a coolant outgoing passage is provided inside the four corners. And a return line for the coolant, each of which is provided with one set of the main coolant lines, and the four sets of the main coolant lines are sequentially connected. To form a cooling liquid circuit, and the cooling liquid introduced from one of the plurality of cooling liquid sub-channels formed in one of the front and rear flanges. After the liquid sequentially passes through the four coolant main lines from the first set to the fourth set, the liquid is discharged from the other one of the coolant sub-lines to the outside of the motor machine. The liquid-cooled electric motor according to claim 1, characterized in that:

3. The front and rear flanges are made of aluminum flanges, and the plurality of coolant sub-channels are arranged around a bearing of the rotating main shaft, and a rotational heat of the bearing is provided. The liquid-cooled electric motor according to claim 1, wherein heat is removed from the motor.

4. The front and rear flanges are provided with a seed-shaped recess surrounding the inlet or outlet of the coolant sub-channel on a surface to be sealed and adhered to the end surface of the cylindrical casing. 2. The liquid-cooled electric motor according to claim 1, wherein each of the recesses is provided with a sealing ring.