JPH0555782U - Eddy current reducer rotor - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rotor for an eddy current type speed reducer in which thermal fatigue cracks of a cooling fin are prevented. [Structure] A support ring 13 in which a rotor 1 is fitted on a rotating shaft 11 and a plurality of permanent magnets 8 are circumferentially arranged so that the polarities of adjacent magnets are opposite to each other is provided in the axial direction of the rotating shaft 11. In the speed reducer, in which the pole surface of the permanent magnet 8 is freely movable forward and backward from the position where it is magnetically entirely opposed to the rotor in the required air gap to the position where it is completely separated from the rotor, the outer peripheral surface of the rotor is provided with V in the rotational direction of the rotor. It is bent in a V shape and is provided with a slit 17 at the V-shaped bending apex. [Effect] The thermal stress generated in the cooling fins can be relaxed by the slit at the V-shaped bent apex portion, and the crack generation life of the cooling fin root portion can be greatly increased.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an improvement of an eddy current type speed reducer used for large vehicles such as buses and trucks.

[0002]

[Prior Art]

 As a deceleration device or braking device for large vehicles, in addition to the main brake, the foot brake, the auxiliary brake, the exhaust brake, stable deceleration when descending a long slope and preventing burnout of the foot brake Therefore, an eddy current type speed reducer is used. The eddy current type speed reducer includes one using an electromagnet and one using a permanent magnet.

In the former, an electromagnet having an electromagnetic coil wound around an iron core is used as a magnetic pole, and a large number of the magnetic poles are arranged on both sides of the disk. A magnetic field is generated by energization from a battery power source, and an eddy current phenomenon causes the disk. The torque is generated in the direction of decelerating the vehicle to obtain the braking force (Japanese Patent Laid-Open No. 615774/50). Since the eddy current type speed reducer uses an electromagnet having an electromagnetic coil wound around an iron core as a magnetic pole, it is heavy and has a large outer dimension, and therefore it is disadvantageous to be mounted on a vehicle with a limited space.

The latter was developed in order to eliminate the above-mentioned problems of the eddy current type speed reducer using the electromagnet, and a plurality of permanent magnets are provided by making the polarities of adjacent magnets opposite to each other. A support ring around which a magnet is provided is provided so that the magnetic pole surface of the permanent magnet can move back and forth in a required gap from a position where it is magnetically entirely opposed to the cylindrical portion of the rotor to a position where it is completely separated. An eddy current generated in a cylindrical portion of a rotor is turned on / off by a magnetic circuit of a permanent magnet (Japanese Patent Laid-Open No. 1-234043).

The temperature of the rotor of the eddy current type speed reducer rises due to the brake operation, and there are the following two. Temperature rise due to short-time braking, temperature rise due to long-term braking or repeated braking. In the former case, the heat capacity of the rotor is mainly involved, and in the latter case, the cooling capacity of the rotor is concerned.

Among these, in order to eliminate the latter problem, in order to suppress an increase in rotor temperature during long-term continuous braking or repetitive braking, as shown in FIG. 3, the rotor 1 is attached to the outer peripheral surface of the cylindrical portion of the rotor 1. A rotor of an eddy current type speed reducer in which a large number of cooling fins 5'bent in a V shape in the rotational direction are circumferentially arranged at equal intervals has been proposed (Japanese Utility Model Publication No. 3-543376).

When the rotor 1 is used, when the rotor rotates, the cooling air flows inwardly from both sides of the cooling fin 5'as shown by arrows in FIGS. 4 (a) and 4 (b). Flows forcibly in the direction and is discharged upward from the bend. During that time, heat is exchanged while the rotor is in contact with the cooling fins and the heat dissipation surface of the outer peripheral surface of the cylindrical portion, and the rotor is cooled. As a result, it is possible to prevent the rotor from reaching an abnormally high temperature.

[0008]

[Problems to be solved by the device]

 As described above, when a rotor having a V-shaped bent cooling fin is used in the eddy current type speed reducer, the rotor is efficiently cooled, and as a result, the rotor is prevented from becoming an abnormally high temperature. it can. An example of the temperature distribution of the cooling fins during braking (at the maximum temperature) in this case is shown in FIG. Since the inner surface side of the cooling fin 5'is connected to the outer cylinder 2 forming the cylindrical portion of the rotor by welding, the temperature becomes high due to heat conduction from the rotor. In particular, the central part of the inner surface of the cooling fin has the largest amount of heat conduction from the rotor, and therefore has the highest temperature in the cooling fin. On the contrary, the outside of the cooling fins is cooled by air cooling, so the temperature is lower than that of the inside. In particular, the end of the cooling fin outer surface has the lowest temperature.

In this case, the thermal expansion of the inner surface portion and the central portion of the cooling fin is large, and the thermal expansion of the outer surface portion and the end portion thereof is small. Therefore, the thermal expansion of the central part of the inner surface of the cooling fins is restrained by the outer surface of the cooling fins, and the thermal stress of compression is generated, and the plastic strain of compression is generated in the central part of the inner surface of the cooling fins, which has the highest temperature in the cooling fins. To do.

On the other hand, the rotor does not generate heat during non-braking, and the entire rotor is air-cooled, so that the temperature of the rotor and that of the cooling fin become substantially uniform. At this time, since the plastic strain generated during braking (at high temperature) remains in the center of the inner surface of the cooling fin, residual tensile stress occurs.

By repeating the braking and non-braking, the above-mentioned compressive stress and tensile stress are applied to the central portion of the cooling fin inner surface, so that the inner surface of the cooling fin, that is, the rotor at the apex of the V-shaped cooling fin. Thermal fatigue cracks occur at the connection.

When such a thermal fatigue crack occurs, a gap is created between the cooling fin and the rotor, so that the cooling effect of the rotor by the cooling fin is reduced and the rotor becomes high in temperature. Further, if the thermal fatigue crack further develops, the cooling fins may deviate, and it is necessary to prevent the occurrence of thermal fatigue crack from the viewpoint of safety.

The present invention provides a rotor for an eddy current type speed reducer in which the above-mentioned thermal fatigue crack is prevented.

[0014]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the rotor of the eddy current type speed reducer of the present invention has a plurality of permanent magnets in which a rotor is fitted to one end of a rotating shaft so that the polarities of adjacent magnets are opposite to each other. The support ring that is installed around the pole has a length that allows the pole face of the permanent magnet to move in the axial direction of the rotating shaft from the position where it is magnetically entirely opposed to the rotor in the required gap to the position where it is completely separated from the rotor. In a speed reducer in which a large number of cooling fins bent in a V shape in the rotor rotation direction are circumferentially arranged at equal intervals on the outer peripheral surface of the rotor, the V-shaped apex of the cooling fins It is a rotor of an eddy current type speed reducer equipped with slits.

In the rotor of the eddy current type speed reducer, the slit width is 0.1 to 1. It is a rotor of an eddy current type speed reducer having a slit of 0 mm.

[0016]

[Action]

 A large number of cooling fins bent in a V shape in the rotor rotation direction are circumferentially arranged on the outer peripheral surface of the rotor cylindrical portion, and slits are provided at the V-shaped apex portions of the cooling fins. . Therefore, at the maximum temperature, the central portion of the inner surface of the cooling fin thermally expands, but this thermal expansion is constrained in the radial direction but can freely expand toward the slit side in the rotational direction. At low temperatures, the effect of slits reduces tensile stress. Therefore, since the compressive and tensile thermal stresses associated with the thermal cycle are reduced, the crack initiation life at the center of the inner surface of the cooling fin becomes longer than that of the rotor of the conventional eddy current type speed reducer.

As a result of an experiment, the slit provided in the V-shaped bent portion of the cooling fin has a slit width of 0. It is desirable to set it to 1 to 1.0 mm. That is, when the slit width is smaller than 0.1 mm, the effect of relaxing the thermal stress is insufficient and a sufficient life extension effect cannot be obtained. Further, when the slit width exceeds 1.0 mm, the amount of air passing between the slits becomes large and a sufficient cooling effect cannot be obtained.

[0018]

【Example】

 An embodiment of this invention will be described with reference to FIGS. The mounting disk 6 of the rotor 1 is attached to the support member 16 fitted to one end of the rotary shaft 11 by a plurality of bolts 9. In this rotor 1, an outer cylinder 2 and an inner cylinder 3 are opposed to each other with a required space to form a cylindrical portion, and the outer cylinder 2 and the inner cylinder 3 are connected at their cylinder ends by a large number of arms 4 to form an outer cylinder 2 A large number of cooling fins 5 which are bent in a V-shape in the rotation direction of the rotor on the outer peripheral surface of the rotor and are provided with slits 17 in the V-shaped bent portion are circumferentially arranged at equal intervals, and one of the inner cylinders 3 is provided. A mounting disk 6 is provided on the end face of the.

In the space between the outer cylinder 2 and the inner cylinder 3, a support ring 13 having a width commensurate with the cylinder length is interposed. The support ring 13 is attached to a support plate 15 axially supported by a rotary shaft 11 via a bearing 14, and is supported by a plurality of guide rods (not shown) projecting in the axial direction of the rotary shaft 11. By moving the rod 7 penetrating the support ring 13 in the width direction forward and backward by the cylinder 10, the length from the position facing the rotor cylindrical portion to the position magnetically deviated is provided so as to be movable forward and backward.

On the outer peripheral surface of the support ring 13, a plurality of permanent magnets 8 made of rare earth magnets to which pole pieces are attached are arranged so that the magnetic poles of adjacent magnets are opposite to each other. The permanent magnet group is housed in the magnetic shield case 12 attached to the support plate 15 to prevent magnetic leakage.

The speed reducer is used, for example, by attaching a mounting bracket (not shown) provided on the support plate 15 to the vehicle body and connecting the rotating shaft 11 to the propeller shaft.

When the support ring 13 is retracted and the permanent magnet group is magnetically separated from the cylindrical portion of the rotor 1, no eddy current flows in the rotor, so the rotor 1 rotates with a predetermined torque. The brake is off. When the cylinder 10 is started in this brake OFF state, the rod 7 advances and the support ring 13 advances, so that the pole pieces attached to the permanent magnet 8 are entirely opposed to the inner surface of the outer cylinder 2 with a predetermined gap. Then, a magnetic circuit is formed between the permanent magnet 8, the outer cylinder 2, and the support ring 13 which are adjacent to each other, so that the so-called brake is turned on, the maximum braking torque is generated, and the vehicle is greatly decelerated.

By repeating the above braking operation, a large amount of heat is generated and tends to be stored in the outer cylinder 2 of the rotor. However, the rotation of the rotor causes the cooling air to be forced between the cooling fins 5 at the center. The rotor flows sufficiently in the direction of the bent portion and heat is exchanged efficiently during that time, so the rotor is not cooled sufficiently and does not reach an abnormally high temperature.

Next, for comparison with the eddy current type speed reducer of the present invention, which is bent in a V shape and in which the cooling fins 5 having slits 17 in the V shape bent portion are circumferentially arranged, A durability test was performed using an eddy current type speed reducer provided with a V-shaped bent cooling fin 5'without a hood. In implementing this invention, the slit width w is 0.1 mm, 0. It was 5 mm, 1.0 mm, and 2.0 mm.

In the durability test, the eddy current type speed reducer shown in FIG. 1 to which the above rotor is attached is mounted on an actual truck, the rotor speed is fixed at 3800 rpm on a bench tester, and braking is turned on / off. The operation was repeated. At this time, changes in temperature of the center of the inner surface of the rotor (highest temperature site) and the center of the outer surface (cooling fin V-shaped apex root) were examined. The result is shown in FIG. From this figure, it can be seen that the maximum temperature at the center of the inner surface of the rotor is about 680 ° C and the minimum temperature is about 100 ° C.

The above-mentioned braking on / off operation was continued until a crack was generated in the cooling fin, and the number of repetitions until the crack was generated was measured. As a result of the durability test, the maximum and minimum temperatures during the thermal cycle and the cracks generated at the center of the outer surface of the rotor (the cooling fin V-shaped apex root, and the slit center when slits are used) Table 1 shows the number of on / off repetitions of.

[0027]

[Table 1]

From the above test results, it can be seen that the cooling fin having the slit in the V-shaped bent portion according to the present invention has a significantly longer cracking life than the cooling fin having no slit.

[0029]

[Effect of the device]

 In this invention, a large number of cooling fins having a V-shaped bending in the rotor rotation direction on the outer peripheral surface of the rotor cylindrical portion of an eddy current type speed reducer using a permanent magnet and having slits at the V-shaped bending apex are provided. Since they are circumferentially arranged at intervals, the amount of heat generated by the brake operation is sufficiently exchanged and cooled by the cooling air forced to flow inward between the cooling fins as the rotor rotates. In addition, the V-shaped slit apex can reduce the thermal stress generated in the cooling fins due to the thermal cycles of braking and non-braking, greatly increasing the cracking life of the cooling fin roots. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an eddy current type speed reducer having a cooling fin provided with a slit at a V-shaped bending apex according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing the flow of cooling air in the cooling fin of the present invention, (a) is a plan view of the cooling fin portion,
Similarly, (b) is a front view.

FIG. 3 is a perspective view of a rotor having a conventional V-shaped bent cooling fin.

4A and 4B are explanatory views showing the flow of cooling air in a conventional V-shaped bent cooling fin, FIG. 4A is a plan view of a cooling fin portion, and FIG.

FIG. 5 is an explanatory diagram showing an example of a temperature distribution of a cooling fin portion of a rotor of an eddy current type speed reducer during braking (at maximum temperature).

FIG. 6 is a graph showing temperature changes at the center of the inner surface of the rotor and the center of the outer surface of the rotor in the repeated braking on / off operation durability test in the example of the present invention.

[Explanation of symbols]

 1 Rotor 2 Outer Cylinder 3 Inner Cylinder 4 Arm 5 Cooling Fin 6 Mounting Disc 7 Rod 8 Permanent Magnet 9 Bolt 10 Cylinder 11 Rotating Shaft 12 Magnetic Shield Case 13 Support Ring 14 Bearing 15 Support Plate 16 Support Member 17 Slit

Claims (2)

[Scope of utility model registration request] 1. A rotor is fitted to one end of a rotary shaft,
A support ring, in which a plurality of permanent magnets are arranged so that the polarities of the adjacent magnets are opposite to each other, is magnetically entirely opposed to the rotor in the axial direction of the rotating shaft with the pole faces of the permanent magnets having a required gap. It is a speed reducer provided so as to be able to advance and retreat from a position where the rotor is completely removed to a position where the entire surface is disengaged. A large number of cooling fins bent in a V shape in the rotor rotation direction are circled at equal intervals on the outer peripheral surface of the rotor. A rotor for an eddy current type speed reducer, characterized in that a slit is provided at a V-shaped apex portion of a cooling fin in a circumferentially arranged device. 2. A rotor is fitted to one end of the rotary shaft,
A support ring, in which a plurality of permanent magnets are arranged so that the polarities of the adjacent magnets are opposite to each other, is magnetically entirely opposed to the rotor in the axial direction of the rotating shaft with the pole faces of the permanent magnets having a required gap. It is a speed reducer provided so as to be able to advance and retreat from a position where the rotor is completely removed to a position where the entire surface is disengaged. A large number of cooling fins bent in a V shape in the rotor rotation direction are circled at equal intervals on the outer peripheral surface of the rotor. In the peripherally arranged device, the slit width is 0.1 to 1.0 m at the V-shaped vertex of the cooling fin.
A rotor for an eddy current type speed reducer characterized by having a slit of m.