JP2007014069A - Motor with rotation speed detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor fitted with a rotation speed detector which has such structure that heat is not conducted to a rotation speed detector such as a rotary encoder or the like despite of the low-cost. <P>SOLUTION: A rotation speed detector 23 is installed at the end of the shaft 11 of a motor 10, and a shaft 24 between the above motor 10 and the above rotation speed detector 23 is provided with a cooling part which has an air vent 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric motor provided with a rotation speed detector such as a rotary encoder.

  In precision control motors such as servo motors used in precision machines such as robots, as shown in FIG. 8, a rotary encoder 43 is installed to detect the rotation speed and rotation angle of the motor 42. . The main types of rotary encoders 43 currently used are photoelectric rotary encoders using light, magnetic rotary encoders using magnetism, and the like. The components of these rotary encoders 43 include many semiconductor elements. Is used.

  For this reason, the rotary encoder 43 may malfunction due to intrusion of dust, oil, moisture, etc. In many cases, it is attached to the shaft end opposite to the output shaft of the electric motor 42.

  However, the semiconductor elements used in the rotary encoder 43 are vulnerable to high temperatures, and the life of the rotary encoder 43 may be shortened as the temperature around the rotary encoder 43 increases. Further, when the semiconductor element of the rotary encoder 43 does not function normally due to high temperature, there is a possibility that the accuracy and the malfunction may be reduced and the correct rotation speed and rotation angle cannot be detected.

As a path for transferring heat from the electric motor 42 to the rotary encoder 23,
1. 1. When the temperature inside the rotary encoder cover 40 rises from the bracket 44 of the electric motor 42 to the rotary encoder cover 40 (see FIG. 8). 2. When the temperature of the rotary encoder 43 rises from the bracket 44 of the electric motor 42 through the leaf spring 41 (see FIG. 8) of the rotary encoder 23. A case where the temperature of the rotary encoder 43 increases from the shaft 45 of the electric motor 42 to the rotary encoder 43 can be considered.

  Of these paths, the above three paths transmit the most heat, so that the axial length of the joint shaft 46 between the rotary encoder 43 and the electric motor 42 is increased as shown in FIG. Measures are taken. In addition, a mechanism for preventing the temperature of the rotary encoder 43 from increasing is disclosed in Patent Document 1 below.

JP 2000-32710 A

  However, in the electric motor with a rotational speed detector disclosed in Patent Document 1, a plurality of radial cooling fins are provided on the joint shaft that couples the detector shaft to the motor shaft. An extra load is applied. Moreover, since a cooling fin etc. must be newly provided, a number of parts will increase and cost will increase.

  Moreover, as shown in FIG. 9, when the distance between the rotary encoder 43 and the electric motor 42 is long, there is a possibility that a sufficient distance cannot be secured due to space restrictions. Further, since it is necessary to secure the mounting accuracy of the shaft 45 and the rotary encoder 43 of the electric motor 42, much labor is required and the cost increases.

  Accordingly, an object of the present invention is to provide an electric motor with a rotational speed detector having a structure that prevents heat from being transmitted to a rotational speed detector such as a rotary encoder while being low in cost.

  A first invention for solving the above-described problem (corresponding to claim 1) is that a rotation speed detector is installed at an end of a shaft of an electric motor, and the shaft between the electric motor and the rotation speed detector is installed. A cooling part having a vent hole is provided.

  A second invention for solving the above-mentioned problems (corresponding to claim 2) is the electric motor with a rotation speed detector according to the first invention, wherein the vent hole is formed in a radial direction, an axial direction, or a radial direction and an axial direction. It is provided in both.

  A third invention (corresponding to claim 3) for solving the above-mentioned problem is that a rotation speed detector is installed at the end of the shaft of the electric motor, and the shaft between the electric motor and the rotation speed detector is installed. A resistance portion having a low thermal conductivity is provided.

  A fourth invention for solving the above-mentioned problem (corresponding to claim 4) is an electric motor with a rotational speed detector according to the third invention, wherein a rotational speed detector is installed at an end of the shaft of the electric motor. The diameter of the shaft between the electric motor and the rotation speed detector is reduced.

  A fifth invention for solving the above-mentioned problems (corresponding to claim 5) is the electric motor with a rotation speed detector according to the third invention or the fourth invention, wherein the resistance portion is provided with a vent hole in a radial direction. And a vent hole is provided in the disk member attached to the rotation speed detector side of the resistance portion in the axial direction.

  According to the first aspect of the present invention, the rotation speed detector is installed at the end of the shaft of the electric motor, and the cooling section having the vent hole is provided in the shaft between the electric motor and the rotation speed detector. Therefore, it is possible to prevent the heat from being transferred to the rotational speed detector.

  According to the second invention, the surface area of the shaft is increased by providing the vent holes in the radial direction, the axial direction, or both the radial direction and the axial direction, so that the heat generated in the electric motor is cooled, and the heat is detected by the rotational speed. Can be prevented from being transmitted to the vessel. In addition, by providing the vent hole, the volume of the cooling unit is reduced, thereby increasing the resistance of heat conduction, so that the heat of the electric motor can be prevented from being transmitted to the rotation speed detector.

  According to the third invention, the rotational speed detector is installed at the end of the shaft of the electric motor, and the resistance portion having low thermal conductivity is provided in the shaft between the electric motor and the rotational speed detector. Since the conductivity decreases, it is possible to prevent the heat generated by the electric motor from being transmitted to the rotation speed detector.

  According to the fourth invention, the resistance of heat conduction is increased by installing the rotation speed detector at the end of the shaft of the electric motor and reducing the diameter of the shaft between the electric motor and the rotation speed detector. The heat generated in can be prevented from being transmitted to the rotational speed detector. Further, since the shaft diameter is reduced, the amount of material to be used can be reduced, so that an increase in cost can be suppressed.

  According to the fifth aspect of the present invention, the surface area of the shaft is increased by providing a vent hole in the resistance portion in the radial direction and providing the vent hole in the axial direction in the disk member attached to the rotation speed detector side of the resistance portion. The heat generated by the electric motor is cooled and the heat can be prevented from being transmitted to the rotation speed detector. Further, since the resistance of heat conduction is increased, it is possible to prevent the heat generated by the electric motor from being transmitted to the rotation speed detector.

  A motor with a rotation speed detector according to the present invention will be described with reference to FIGS. FIG. 1 is a main part configuration diagram of a motor with a rotation speed detector according to a first embodiment, FIG. 2 is a main part configuration diagram of a motor with a rotation speed detector according to a second embodiment, and FIG. 3 is a rotation speed according to the third embodiment. FIG. 4 is a main part configuration diagram of a motor with a rotation speed detector according to a fourth embodiment, FIG. 5 is a main part configuration diagram of a motor with a rotation speed detector according to a fifth embodiment, FIG. 6 is a main part configuration diagram of a motor with a rotation speed detector according to a sixth embodiment, and FIG. 7 is a side view of the motor with a rotation speed detector.

  1A to 3A show the AA cross section of FIG. 7, the BB cross section of FIG. 1 to FIG. 1B, and the CC cross section of FIG. 2 to FIG. ), The DD cross section of FIG. 3 is shown in FIG. Moreover, the dashed-dotted line in each figure shows the center position of the motor with a rotation speed detector.

  The outline of the motor with a rotation speed detector according to the present embodiment will be described below. As shown in FIG. 7, the electric motor 10 has a shaft 11 at the center thereof. A rotor 12 is installed on the radially outer side of the shaft 11. The electric motor 10 is covered with a frame 13. A stator 14 is installed inside the frame 13. The stator 14 is installed so as to face the rotor 12 with an interval. A coil 15 is wound around the stator 14 in the axial direction.

  Brackets 16 a and 16 b are installed at the end of the frame 13 in the axial direction. Bearings 18a and 18b are respectively installed in the central portions of the brackets 16a and 16b. The side surface of the shaft 11 is in contact with the bearings 18a and 18b, and the shaft 11 passes through the bearings 18a and 18b. An output shaft 17 is provided at the end of the shaft 11 that passes through the bearing 18b.

  An intermediate shaft 24 is installed in the axial direction at the end of the shaft 11 passing through the bearing 18a. A small shaft 25 is installed at the end of the intermediate shaft 24 opposite to the shaft 11. A joint shaft 19 is installed at the end of the small shaft 25 opposite to the intermediate shaft 24.

  A suspension ring 20 is provided on the upper surface of the frame 13 to suspend and move the motor 10 when the motor 10 is installed. A heat radiating plate 21 is provided outside the frame 13 to cool the electric motor 10.

  A rotary encoder cover 22 is installed on the side surface in the axial direction of the bracket 16a. A rotary encoder 23 is installed inside the rotary encoder cover 22. The rotary encoder 23 detects the rotation speed and rotation angle of the electric motor 10 by detecting the rotation speed and rotation angle of the joint shaft 19 using light, magnetism, and the like.

  Next, the structure of the intermediate shaft 24 between the bearing 18a on the rotary encoder 23 side and the rotary encoder 23 will be described. In this embodiment, the intermediate shaft 24 is cooled so that the heat of the electric motor 10 is not transmitted to the rotary encoder 23 so that the cooling portion is provided on the intermediate shaft 24.

  As shown in FIG. 1A, eight vent holes 26 are provided at equal intervals in the radial direction about the rotation axis of the electric motor 10 on the intermediate shaft 24. As shown in FIG. 1B, the position of the vent hole 26 is close to the electric motor 10 (see FIG. 7) on the shaft 11 side. Thereby, the heat from the electric motor side which is a heat source can be efficiently cooled. A portion where the air holes 26 in the intermediate shaft 24 intersect with each other is a cylindrical cavity. A small shaft 25 is provided at the end of the intermediate shaft 24 opposite to the shaft 11.

  According to the electric motor with a rotation speed detector according to the present embodiment, the surface area of the intermediate shaft 24 is increased by providing the vent hole 26 so that the heat of the electric motor 10 is not transmitted to the rotary encoder 23 (see FIG. 7). Can do.

  Further, the larger the diameter of the vent hole 26 is, the larger the cylindrical cavity inside the intermediate shaft 24 is, and the surface area is increased to increase the cooling efficiency. Furthermore, since the resistance of heat conduction increases as the volume of the intermediate shaft 24 decreases, the heat of the electric motor 10 can be prevented from being transmitted to the rotary encoder 23 (see FIG. 7). Thus, cooling efficiency and thermal resistance can be increased by increasing the diameter of the air hole 26 within a range in which sufficient strength can be secured.

  Hereinafter, the motor with a rotation speed detector according to the second embodiment will be described. The structure of the motor with a rotation speed detector other than the intermediate shaft 24 is substantially the same as that of the first embodiment. As shown in FIG. 2, in Example 2, eight vent holes 27 were provided in the intermediate shaft 24 at equal intervals in the axial direction in parallel with the rotation axis. The depth of the vent hole 27 is set to a depth that does not penetrate the shaft 11 on the electric motor 10 (see FIG. 7) side. A small shaft 25 is provided at the end of the intermediate shaft 24 opposite to the shaft 11.

  According to the motor with a rotation speed detector according to the present embodiment, the larger the diameter of the vent hole 27, the larger the surface area and the higher the cooling efficiency. Furthermore, since the resistance of heat conduction increases as the volume of the intermediate shaft 24 decreases, the heat of the electric motor 10 can be prevented from being transmitted to the rotary encoder 23 (see FIG. 7). Thus, the cooling efficiency and the thermal resistance can be increased by increasing the diameter of the vent hole 27 within a range in which sufficient strength can be secured.

  Hereinafter, the motor with a rotation speed detector according to the third embodiment will be described. The structure of the motor with a rotation speed detector other than the intermediate shaft 24 is substantially the same as that of the first embodiment. As shown in FIG. 3, in the third embodiment, eight vent holes 28 are provided at equal intervals in the radial direction around the rotation axis in the intermediate shaft 24, and eight in the axial direction parallel to the rotation axis. Ventilation holes 29 were provided at equal intervals.

  The radial vent hole 28 and the axial vent hole 29 are connected inside the intermediate shaft 24, and the radial vent hole 28 is positioned closer to the shaft 11. A portion where the air holes 26 in the intermediate shaft 24 intersect with each other is a cylindrical cavity. A small shaft 25 is provided at the end of the intermediate shaft 24 opposite to the shaft 11.

  According to the electric motor with a rotation speed detector according to the present embodiment, the larger the diameter of the vent holes 28 and 29, the larger the cylindrical cavity inside the intermediate shaft 24, the surface area is increased, and the cooling efficiency is increased. Furthermore, since the resistance of heat conduction increases as the volume of the intermediate shaft 24 decreases, the heat of the electric motor 10 can be prevented from being transmitted to the rotary encoder 23 (see FIG. 7). Thus, the cooling efficiency and the thermal resistance can be increased by increasing the diameters of the vent holes 28 and 29 within a range in which sufficient strength can be secured.

  Hereinafter, the motor with a rotation speed detector according to the fourth embodiment will be described. The structure of the motor with a rotation speed detector other than the intermediate shaft 24 is substantially the same as that of the first embodiment. As shown in FIG. 4, in Example 4, the resistance part 30 was provided in the intermediate shaft 24 using the material with low heat conductivity. Further, a disk member 33 is provided at the end of the low rear portion 30 opposite to the shaft 11. In this embodiment, the resistance portion 30 is a cylindrical member having a hollow central portion, but a plurality of columnar members having low thermal conductivity may be installed on the circumference of the shaft 11 at equal intervals.

  According to the electric motor with a rotation speed detector according to the present embodiment, the thermal conductivity of the intermediate shaft 24 is reduced by providing the resistance portion 30, and the surface area is increased and the cooling efficiency is increased by making the central portion hollow. Will increase. Furthermore, since the resistance of heat conduction is increased by reducing the volume of the intermediate shaft 24, it is possible to prevent the heat of the electric motor 10 (see FIG. 7) from being transmitted to the rotary encoder 23 (see FIG. 7). Moreover, since the center part of the resistance part 30 is made hollow, the amount of material to be used can be reduced, so that an increase in cost can be suppressed.

  Hereinafter, the motor with a rotation speed detector according to the fifth embodiment will be described. The structure of the electric motor with a rotation speed detector other than the small shaft 25 is substantially the same as that of the first embodiment. As shown in FIG. 5, in Example 5, the shaft diameter of the small shaft 25 between the intermediate shaft 24 and the joint shaft 19 was reduced.

  According to the electric motor with a rotation speed detector according to the present embodiment, the thermal conductivity is reduced by reducing the shaft diameter of the small shaft 25, so that the resistance of the heat conduction is increased by reducing the volume of the small shaft 25. Therefore, the heat of the electric motor 10 (see FIG. 7) is hardly transmitted from the shaft 11 to the rotary encoder 23. Further, since the shaft diameter of the small shaft 10 is reduced, the amount of material to be used can be reduced, so that an increase in cost can be suppressed.

  Hereinafter, the motor with a rotation speed detector according to the sixth embodiment will be described. The structure of the motor with a rotation speed detector other than the intermediate shaft 24 is substantially the same as that of the first embodiment. As shown in FIG. 6, in Example 6, the intermediate shaft 24 of Example 4 was provided with a vent hole. The resistance portion 30 is provided with a vent hole 31 in the radial direction, and the disk member 33 is provided with a vent hole 32 in the axial direction.

  According to the motor with a rotation speed detector according to the present embodiment, the ventilation hole 31 is provided in the resistance portion 30 and the ventilation hole 32 is provided in the disk member 33, thereby increasing the surface area and increasing the cooling efficiency. Furthermore, since the resistance of heat conduction is increased by reducing the volume of the intermediate shaft 24, it is possible to prevent the heat of the electric motor 10 (see FIG. 7) from being transmitted to the rotary encoder 23. Thus, cooling efficiency and thermal resistance can be improved by enlarging the diameters of the air holes 31 and 32 within a range that can ensure sufficient strength.

  The present invention is effective for making it difficult for heat generated by the electric motor to be transmitted to the rotation speed detector and for preventing temperature increase of the rotation speed detector.

It is a principal part block diagram of the electric motor with a rotation speed detector which concerns on Example 1. FIG. FIG. 6 is a configuration diagram of a main part of an electric motor with a rotation speed detector according to a second embodiment. FIG. 6 is a main part configuration diagram of a motor with a rotation speed detector according to a third embodiment. FIG. 6 is a main part configuration diagram of a motor with a rotation speed detector according to a fourth embodiment. FIG. 9 is a main part configuration diagram of a motor with a rotation speed detector according to a fifth embodiment. FIG. 10 is a main part configuration diagram of a motor with a rotation speed detector according to a sixth embodiment. It is a side view of an electric motor with a rotation speed detector. It is a side view of the electric motor with a rotation speed detector which has the conventional rotary encoder cover. It is a side view of the electric motor with a rotation speed detector which has the conventional leaf | plate spring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric motor 11 Shaft 12 Rotor 13 Frame 14 Stator 15 Coil 16 Bracket 17 Output shaft 18a, 18b Bearing 19 Joint shaft 20 Suspension ring 21 Heat sink 22 Rotary encoder cover 23 Rotary encoder 24 Intermediate shaft 25 Small shafts 26, 27, 28 , 29, 31, 32 Ventilation hole 30 Resistance part 33 Disk member 40 Rotary encoder cover 41 Leaf spring 42 Electric motor 43 Rotary encoder 44 Bracket 45 Shaft 46 Joint shaft

Claims (5)

Install a rotation speed detector at the end of the motor shaft,
A motor having a rotation speed detector is provided with a cooling portion having a vent hole in a shaft between the motor and the rotation speed detector. In the electric motor with a rotation speed detector according to claim 1,
The motor with a rotation speed detector is characterized in that the vent hole is provided in a radial direction, an axial direction, or both a radial direction and an axial direction. Install a rotation speed detector at the end of the motor shaft,
An electric motor with a rotational speed detector, characterized in that a resistance portion having a low thermal conductivity is provided on a shaft between the electric motor and the rotational speed detector. In the electric motor with a rotation speed detector according to claim 3,
A motor with a rotational speed detector, characterized in that a diameter of a shaft between the electric motor and the rotational speed detector is reduced. In the electric motor with a rotational speed detector according to claim 3 or claim 4,
A vent hole is provided in the resistance portion in the radial direction,
An electric motor with a rotation speed detector is provided with a vent hole in an axial direction in a disk member attached to the rotation speed detector side of the resistance portion.

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