JP3748249B2 - Motor cooling device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cooling device for an electric motor used, for example, for driving a spindle of a machine tool, and more particularly to an apparatus for cooling a stator with a refrigerant liquid.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electric motor cooling apparatus that is used for driving a machine tool spindle and that cools a stator with a refrigerant liquid is as shown in FIG. FIG. 5 is a sectional side view of an electric motor showing the prior art.
In the figure, 21 is a rotating shaft, 22 is a rotor, 23 is a stator core, 24 is a frame, 25 is a mold resin, 26 is a stator coil, 27 is an inlet, 28 is an outlet, 29 is a coolant groove, Reference numeral 30 denotes a locking screw.
A stator core 23 made of a laminated core is provided opposite to the outer periphery of the rotor 22 fixed to the rotary shaft 21. The stator core 23 includes a stator coil 26, and a frame 24 is fitted to the outer periphery of the stator core 23 via a resin film. In addition, on the surface that contacts the outer periphery of the stator core 23 on the inner periphery of the frame 24, a spiral multi-row refrigerant liquid groove 29 is provided, and at both ends of the refrigerant liquid groove 29, refrigerant liquid inlets 27 and An outlet 28 is provided and opens to the outer periphery of the frame 24. Further, a mold resin 25 is filled between the inner periphery of the frame 24, the end face of the stator core 23, and the coil end of the stator coil 26, so that heat generated by the stator coil 26 can be easily transmitted to the frame 24. It is. Then, between the stator core 23 and the frame 24, a rotation-preventing screw 30 is screwed from the frame 24 toward the stator core 23 so that torque applied between the stator core 23 and the frame 24 is transmitted. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
No. 7-49773 (Fig. 1)
[0004]
[Problems to be solved by the invention]
By the way, in the means for cooling the stator by flowing the refrigerant liquid in the refrigerant liquid groove 29 provided in the frame 24 as in the prior art, in order to further increase the cooling efficiency, generally the capability of the pump of the cooling unit (not shown). To increase the flow rate of the refrigerant liquid or increase the number of spiral refrigerant liquid grooves 29 to increase the contact time with the refrigerant contributing to heat transfer, the time for the refrigerant to contact the stator portion Is used.
However, the means for increasing the pump capacity of the former cooling unit has the problem that the cost of the cooling unit itself increases due to the increase in the capacity of the pump motor and the power consumption during operation increases. there were.
On the other hand, the latter means for increasing the number of the spiral refrigerant liquid grooves 29 increases the number of machining steps for the member for forming the refrigerant liquid grooves 29, which causes an increase in cost. There was a problem that it was difficult to respond to the request.
[0005]
Further, according to the prior art, the rotating screw 30 has to be tightened in the radial direction from the outer periphery of the frame 24 toward the stator core 23. Therefore, if the fastening force in the radial direction of the locking screw 30 becomes too strong, the frame 24 The roundness of the frame 24 and the fitting surfaces of the frame 24 with the brackets 31 and 32 provided on the load side and the anti-load side are distorted. There was a problem of falling down and causing vibration of the electric motor.
The above fastening method is a method of fastening from the radial direction around the entire circumference of the frame 24 while changing the posture of the motor. There was a problem that the cost increased.
[0006]
The present invention has been made in order to solve the above problems, can improve the cooling efficiency without increasing the flow rate of the refrigerant liquid, and can reduce the number of machining steps of the member forming the refrigerant liquid groove, In addition, an object of the present invention is to provide an inexpensive motor cooling device that is not affected by the roundness of the frame and has a small number of assembly steps.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, the present invention of claim 1 is directed to a stator core made of a laminated core having a stator coil, a first frame provided on an outer peripheral surface of the stator core, and the first frame. A second frame provided in contact with the outer peripheral surface of the first frame, and a refrigerant formed with a minute annular gap extending in the circumferential direction on a surface in contact with the other one of the first frame and the second frame An electric motor cooling device that cools a stator by flowing a refrigerant liquid through the refrigerant liquid groove , wherein the refrigerant liquid groove is provided with a tapered portion at least in the vicinity of the inlet of the refrigerant liquid. It is characterized by.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional side view of an electric motor according to a first embodiment of the present invention, FIG. 2 shows the structure of a frame, a refrigerant liquid groove, and an inflow port, and FIG. The front sectional view along the line, (b) is a sectional view of the inlet of (a) seen from the Y direction.
In the figure, 1 is a rotating shaft, 2 is a rotor, 3 is a stator core, 4 is a stator coil, 5 is a coolant groove, 6 is an inlet, 7 is a supply pipe, 8 is an outlet, and 9 is a recovery. Piping 10 for the first frame, 10A for the female threaded portion, 11 for the second frame, 11A for the through hole, 11B for the stepped portion, 12 for the cooling unit, 13 for the fastening screw, 14 and 15 for the brackets, 16 and 17 Is a bearing. In addition, the structure in which the stator core 3 provided with the stator coil 4 is provided on the outer periphery of the rotor 2 fixed to the rotating shaft 1 is the same as that of the prior art.
[0009]
The features of the present invention are as follows.
That is, as a component corresponding to the frame of the prior art, a first frame 10 provided on the outer peripheral surface of the stator core 3 and a second frame 11 provided in contact with the outer peripheral surface of the first frame 10 It is a point using what consists of. The surface of the first frame 10 that contacts the second frame 11 is provided with a coolant groove 5 having a minute annular gap formed so as to extend in the circumferential direction, and is processed into a smooth concentric cylinder.
In addition, a refrigerant liquid inlet 6 and an outlet 8 are provided at both ends of the refrigerant liquid groove 5, and open to the outer periphery of the second frame 11. An O-ring (not shown) is provided between the first frame 10 and the second frame 11 at both ends of the refrigerant liquid groove 5 to provide a seal so that the refrigerant liquid does not leak.
Furthermore, as shown in FIG. 2, when the cross-sectional area viewed from the inflow direction of the inlet 6 serving as the inlet of the refrigerant liquid groove 5 is A and the cross-sectional area viewed from the axial direction of the refrigerant liquid groove 5 is B, It has a relationship of A> = B.
As shown in FIG. 1, a female screw portion 10A is provided at the end of the first frame 10 to form a stepped portion 11B having a through hole 11A at one end in the axial direction of the second frame 11, and the first frame A stepped portion 11B of the second frame 11 is screwed and fixed in the thrust direction by a fastening screw 13 through a through hole 11A with respect to the female screw portion 10A at the end portion of the ten. The first frame 10 and the second frame 11 are fastened in a space S in which the stator coil 4 is accommodated.
[0010]
In such a configuration, heat due to losses such as copper loss or iron loss generated in the stator coil 4 and the stator core 3 when the motor is operated heats from the first frame 10 to the second frame 11. Although conducted, the refrigerant liquid supplied from the cooling unit 12 through the supply pipe 7 passes through the refrigerant liquid groove 5 provided between the first frame 10 and the second frame 11, and the stator coil 4. The heat generated in the stator core 3 is taken away, and is recovered from the refrigerant liquid groove 5 through the recovery pipe 9 to the cooling unit 12, and heat exchange is performed while repeating the above operation.
[0011]
FIG. 3 shows a comparison of the cooling effect between the present invention and the prior art.
That is, the ratio of the motor loss to the armature coil temperature rise is compared in percentage, and according to this, the present invention can increase the cooling effect by about 20% compared to the conventional case.
[0012]
Since the first embodiment of the present invention has the above-described configuration, the refrigerant liquid groove 5 is processed into a smooth concentric cylindrical shape, so that it is compared with a conventional multi-threaded spiral groove. Further, it is possible to provide an electric motor cooling device that can be easily processed and can reduce the number of machining steps for the member that forms the flow path of the refrigerant liquid, and enables cost reduction.
[0013]
Further, since the refrigerant liquid groove 5 has a minute annular gap formed between the first frame 10 and the second frame 11, without increasing the flow rate of the refrigerant liquid by increasing the pump capacity of the cooling unit, The flow rate of the refrigerant liquid can be increased, and the heat transfer between the first frame 10, the refrigerant liquid groove 5, and the second frame 11 can be improved, and the cooling efficiency can be increased.
[0014]
Furthermore, since the cross-sectional area A as viewed from the inflow direction of the refrigerant liquid groove inlet 6 is made larger than the cross-sectional area B as viewed from the axial direction of the refrigerant liquid groove 5, machining man-hours are reduced and costs are reduced. can do.
[0015]
The present embodiment can solve the problem that the cooling unit itself increases the cost and increases the power consumption during operation.
[0016]
Then, in this embodiment, a stepped portion 11B is formed at one end of the second frame 11 in the axial direction, and the end portion of the first frame 10 and the stepped portion 11B of the second frame 11 are tightened toward the thrust direction. Since the fastening force of the fastening screw 13 is mainly applied in the thrust direction, the influence on the roundness of the first frame 10 and the second frame 11 can be reduced. As a result, the fitting between the load-side and anti-load-side brackets 14 and 15 and the second frame 11 becomes smooth and easy to assemble, and vibration due to the fall of the bearings 16 and 17 does not occur. Further, in the fastening method according to the present embodiment, since the fastening screws 13 are fastened from the second frame 11 toward the thrust direction of the first frame 10, the work can be performed without changing the posture while the electric motor is placed. It is possible to reduce the number of assembly steps and the cost.
Furthermore, since the first frame 10 and the second frame 11 are fastened in the space S in which the stator coil 4 is housed, water or the like enters the motor from the outside via the fastening screw 13. Problems can be prevented and environmental resistance can be improved.
[0017]
FIG. 4 is an enlarged side sectional view of a frame portion showing a second embodiment of the present invention.
The second embodiment differs from the first embodiment in that the refrigerant liquid groove 5 has tapered portions 6A and 8A for reducing the flow velocity of the refrigerant liquid in the vicinity of the refrigerant liquid inlet 6 and in the vicinity of the refrigerant liquid outlet 8. This is the point.
[0018]
In such a configuration, the refrigerant liquid flowing in from the inlet 6 first flows through the entire circumference of the refrigerant liquid groove 5 in the axial position of the inlet 6 before passing through the tapered portion 6A, and then passes through the tapered portion 6A. . And since a refrigerant | coolant liquid flows in uniformly over the perimeter in the axial direction by the side of the outflow port 8 from the refrigerant | coolant liquid groove | channel 5, in a predetermined direction among the circumferential directions of the stator core 3 and the stator coil 4 These can be evenly cooled without being biased.
[0019]
Since the second embodiment of the present invention has the above-described configuration, the flow velocity in the refrigerant liquid groove 5 is increased by providing the tapered portions 6A and 8A, and the heat in the refrigerant liquid groove 5 is increased as compared with the first embodiment. Transmission performance can be improved. Further, in the coolant liquid groove 5 located on the outer periphery of the stator coil 4 in the stator core 3, the coolant liquid flows uniformly into the entire periphery thereof, so that the temperature of the stator core 3 and the stator coil 4 rises. Can be made equal in the circumferential direction to improve the cooling efficiency, and thermal deformation due to uneven thermal expansion can be prevented. For example, when the electric motor according to the present invention is used for driving a machine tool main shaft built-in type (built-in type electric motor), it is possible to prevent the adverse effect of deformation due to uneven thermal expansion on the dimensional change and accuracy of the main shaft member.
In addition, by making the attachment side to the machine tool the refrigerant liquid inlet, the attachment side to the machine tool is further cooled, preventing the transfer of heat from the electric motor to the machine tool, and at the same time, dimensional change of the member due to thermal expansion Alternatively, there is no problem of adversely affecting the machining accuracy.
In the present embodiment, the coolant liquid groove 5 in which a minute annular gap is formed so as to extend in the circumferential direction is provided on the surface of the first frame 10 that contacts the second frame 11. 5 may be provided on the surface of the second frame 11 that contacts the first frame 10.
[0020]
【The invention's effect】
As described above, the present invention has the following effects.
Since the first embodiment of the present invention has the above-described configuration, the coolant liquid groove is processed into a smooth concentric cylindrical shape. Therefore, it is possible to provide a motor cooling device that can easily reduce the machining man-hours of the member that forms the flow path of the refrigerant liquid and enables cost reduction.
[0021]
In addition, since the refrigerant liquid groove has a minute annular gap formed between the first frame and the second frame, the capacity of the refrigerant liquid can be increased without increasing the flow rate of the refrigerant liquid by increasing the pump capacity of the cooling unit. The flow rate can be increased, and the heat transfer between the first frame, the refrigerant liquid groove and the second frame can be improved, and the cooling efficiency can be increased. Furthermore, since the cross-sectional area seen from the inflow direction of the inlet of the refrigerant liquid groove is made larger than the cross-sectional area seen from the axial direction of the refrigerant liquid groove, the number of machining steps can be reduced and the cost can be reduced. Then, the problem that the cooling unit itself increases in cost and power consumption during operation can be solved.
[0022]
In this embodiment, a stepped portion is formed at one end of the second frame in the axial direction, and the end portion of the first frame and the stepped portion of the second frame are fixed in the thrust direction with a fastening screw. For this reason, since the fastening force of the fastening screw is mainly applied in the thrust direction, the influence on the roundness of the first frame and the second frame can be reduced. As a result, the fitting of the load-side and anti-load-side brackets and the frame is smooth and easy to assemble, and vibration due to the falling of the bearing does not occur. Further, in the fastening method according to the present embodiment, since the fastening screws are fastened from the second frame toward the thrust direction of the first frame, the work can be performed without changing the posture while the electric motor is placed. Man-hours can be reduced and costs can be reduced.
[0023]
Furthermore, since the first frame and the second frame are fastened in the space in which the stator coil is housed, the problem of water or the like entering the motor from the outside via the fastening screw is prevented, and the environment resistance is improved. Can be improved.
[0024]
Since the second embodiment of the present invention has the above-described configuration, the flow velocity in the refrigerant liquid groove is increased by providing the tapered portion, and the heat transfer performance in the refrigerant liquid groove is improved as compared with the first embodiment. Can do. In addition, in the refrigerant liquid groove located on the outer periphery of the stator coil in the stator core, the refrigerant liquid flows evenly around the entire circumference, so that the temperature rise of the stator core and the stator coil is increased in the circumferential direction. It becomes equal and can improve a cooling efficiency and can also prevent the thermal deformation by uneven thermal expansion. For example, when the electric motor according to the present invention is used for driving a machine tool spindle built-in type, it is possible to prevent adverse effects of deformation due to uneven thermal expansion on the dimensional change and accuracy of the spindle member.
[0025]
In addition, by making the attachment side to the machine tool the refrigerant liquid inlet, the attachment side to the machine tool is further cooled, preventing the transfer of heat from the electric motor to the machine tool, and at the same time, dimensional change of the member due to thermal expansion Alternatively, there is no problem of adversely affecting the machining accuracy.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an electric motor showing a first embodiment of the present invention.
2A and 2B show a configuration of a frame, a coolant groove, and an inlet, in which FIG. 2A is a front sectional view taken along line XX of FIG. 1, and FIG. 2B is an inlet of FIG. It is sectional drawing which looked at from the Y direction.
FIG. 3 is a diagram showing a comparison of the cooling effect of the present invention and the prior art.
FIG. 4 is an enlarged side sectional view of a frame portion showing a second embodiment of the present invention.
FIG. 5 is a side sectional view of an electric motor showing the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Rotor 3 Stator core 4 Stator coil 5 Refrigerant liquid groove 6 Inlet 6A Taper part 7 Supply pipe 8 Outlet 8A Taper part 9 Recovery pipe 10 First frame 10A Female thread part 11 Second frame 11A Through hole 11B Stepped part,
12 Cooling unit 13 Fastening screw 14, 15 Bracket 16, 17 Bearing

Claims (1)

A stator core made of a laminated core having a stator coil, a first frame provided on the outer peripheral surface of the stator core, a second frame provided in contact with the outer peripheral surface of the first frame, and A refrigerant liquid groove in which a minute annular gap is formed so as to extend in a circumferential direction on a surface in contact with the other one of the first frame and the second frame;
A cooling device for an electric motor that cools a stator by flowing a refrigerant liquid through the refrigerant liquid groove ,
The cooling device for an electric motor, wherein the refrigerant liquid groove is provided with a tapered portion at least in the vicinity of an inlet of the refrigerant liquid .

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