JPH0811053Y2 - Eddy current retarder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an eddy current retarder for applying a decelerating braking force to a vehicle for braking.

[Prior Art] If only the foot brake is used when going down a long slope or the like, the foot brake will be burned and the braking ability will be lost. Therefore, the foot brake and the engine brake are used together. An eddy current retarder using an electromagnetic coil is generally used as a third brake device for generating an effective braking force on a slope or the like (for example, Japanese Patent Laid-Open No.
No. 61574) is known, but it has not been put to practical use because the entire retarder becomes large when an electromagnetic coil is used.

Therefore, the present applicant has proposed an eddy current type retarder in which a permanent magnet is used in place of the electromagnetic coil used in the conventional eddy current type retarder to reduce the size of the retarder.

In this proposal, as shown in FIG. 6, S poles and N poles are alternately arranged in the circumferential direction between the inner peripheral surface of an iron drum-shaped rotor b attached to a rotary shaft a and the rotary shaft a. The permanent magnet c is attached to the stator d so that the stator d can be inserted and removed freely. That is, by inserting the stator d between the inner peripheral surface of the drum-shaped rotor b and the rotating shaft a, a magnetic circuit shown by a broken line in FIG. 7 is formed to form an eddy current on the inner peripheral surface side of the rotor b. e is generated, a braking torque relative to the stator d is generated in the rotor b, and the rotating shaft a is braked. By the way, the eddy current e flowing on the inner peripheral surface of the rotor b basically flows in a direction perpendicular to the two magnetic poles of the permanent magnet c so as to hinder the rotation of the rotor b. Some do not flow, but some flow in a direction that has little to do with braking force.
That is, an eddy current in a direction unrelated to the improvement of the braking force of the rotor b is also generated.

Therefore, in order to make it possible to use the eddy current e that has not been involved in the braking as the braking force, the applicant has made a ring-shaped ring on the inner peripheral surface of the drum-shaped rotor b as shown in FIG. Two groove-shaped grooves f are formed, a good conductor such as copper melted is poured into these grooves f to form a copper ring g, and an eddy current path is formed by this copper ring g to improve the braking force. It has been proposed that That is, the electrical resistance of the copper ring g is smaller than that of the iron material forming the rotor b, and the eddy current e
Is concentrated on the copper ring g, and it is possible to improve the deceleration braking force by about 20%.

[Problems to be Solved by the Invention] However, when an eddy current is concentrated in the copper ring to cause energy loss, the copper ring and the inner peripheral surface of the rotor generate heat at a high temperature to form an inner peripheral surface of the rotor. There is a risk that a difference in thermal expansion will occur between the outer peripheral surface and the rotor, and the copper ring may be peeled off.

An object of the present invention is to provide an eddy current type retarder that is as durable and reliable as possible by expanding the heat dissipation area of a good conductor such as a steel ring to eliminate the temperature difference between the inner and outer peripheral surfaces of the rotor. .

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a drum-shaped rotor made of a ferromagnetic material on a rotating shaft, and a stator having a permanent magnet inside of the rotor is freely movable in a close proximity. Installed in
In an eddy current retarder in which two grooves are provided in parallel on the inner peripheral surface of the rotor along the circumferential direction thereof at a predetermined interval and a good conductor is provided in these grooves, the rotor is provided for each groove. By cutting off a part of the rotor located axially outward, the rotor axial outer side wall of each groove is formed lower than the inner side wall, and the heat dissipation open area of the good conductor provided in the groove is at least the groove It is formed to be larger than the area formed by connecting the opening edges.

[Operation] According to the above configuration, the eddy current generated on the inner peripheral surface of the rotor when the stator is brought close to the rotor causes the good conductor in the two grooves formed in parallel along the circumferential direction of the rotor. Flow in the axial direction (direction contributing to braking) from the inner peripheral surface of the rotor located between the grooves. At this time, the conductor on which the eddy current is concentrated generates heat.

Here, according to the present invention, the conductor is provided in a groove formed by cutting off a part of the rotor located on the outer side in the axial direction of the rotor so that the side wall on the outer side in the axial direction of the rotor is formed lower than the side wall on the inner side. Therefore, the heat dissipation open area becomes larger than that provided in a normal groove in which a part of the rotor is not cut off. Therefore, the heat dissipation of the conductor that generates heat due to the concentrated eddy current is improved.

Further, since the conductor is sandwiched on both sides by the side wall of the groove, the conductor is prevented from falling out of the groove due to thermal expansion and contraction. As described above, according to the present invention, it is possible to prevent the conductor that generates heat from both falling off due to thermal expansion and contraction and improving heat dissipation.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a rotor 4 of an eddy current retarder 1 is attached by a mounting bolt 5 to a flange portion 3 formed on a rotary shaft 2 serving as an output shaft of an automobile transmission, by fastening bolts 5. The rotor 4 is a drum having a disk portion which is an electric conductor and is made of a ferromagnetic material, such as iron, and which extends from the rotation shaft 2 in the radial direction, and a cylindrical axial portion which is parallel to the rotation shaft 2. It is formed into a shape and is provided coaxially with the rotating shaft 2. Inside the rotor 4, a stator 6 is provided in a transmission case or the like (not shown) so as to reciprocate in the axial direction of the drum 7 and prevent rotation. The stator 6 is composed of an annular support ring 8 arranged concentrically with the rotating shaft 2 and a permanent magnet 9 attached on the support ring 8. The permanent magnet 8 is made of a rare earth element such as neodymium (Nd) to have a light, thin, short, and small size so as to exert a strong magnetic force. As shown in FIG. 7, the permanent magnet 8 faces the inner peripheral surface of the rotor 4 having a drum shape. Of the support rings 8 arranged so that the S poles and the N poles are aligned in the radial direction and the polarities are alternately arranged at predetermined intervals in the circumferential direction.
It is installed around. In the embodiment, the permanent magnets 8 are provided in an even number (about 8 to 12). Then, the stator 6 including the permanent magnet 9 and the support ring 8
Is sealed by a casing 10 which allows the stator 6 to reciprocate in the drum-shaped rotor 4. The casing 10 is provided at a position on the inner peripheral side of the drum-shaped rotor 4 and in a position close to the rotor 4, and at a portion facing the rotor 4, a magnetic permeability portion of the stator 6 that allows the magnetism to pass therethrough.
11 is formed. And in the casing 10,
An actuator 14 for reciprocating the stator 6 by air pressure or the like is provided from the solid line portion to the broken line portion shown in FIG. That is, when the actuator 6 moves the stator 6 to the portion shown by the broken line in FIG. 1, the stator 6 enters the magnetic shield state and the deceleration braking of the rotary shaft 2 is released. In addition, two grooves are formed along the circumferential direction of the drum 7 on the inner circumferential surface of the rotor 4 at a portion facing both magnetic poles of the permanent magnet 9 provided on the fixed side stator 6 at both ends in the direction perpendicular to the magnetic pole. 12 are formed in the groove 12, and a copper ring 13 which is an electrically good conductor is formed in the groove 12 so as to form a passage of an eddy current.
Is provided.

As shown in FIG. 1 configured as described above, when the stator 6 is moved to the magnetic permeability portion 11 by the actuator 14, the drum-shaped drum 4 is moved by the relative rotation speed between the rotating rotor 4 and the fixed stator 6. Eddy current is generated on the inner peripheral surface of the rotor 4 (see FIG. 7), the rotor 4 is excited, braking torque is generated between the rotor 4 and the stator 6, and the rotating shaft 2 is decelerated and braked. During this braking, the copper ring 13 forms a path through which an eddy current having a directional component related to deceleration of the rotor 4 flows, and the deceleration efficiency of the rotor 4 is improved.

By the way, the purpose of the present invention is to provide the above-mentioned copper ring.
The high heat of the copper ring 13 that rises with the improvement of the braking force by the 13 is positively radiated to the outside, and the rotor 4 and the copper ring 13
It is intended to prevent thermal deformation and peeling due to a temperature difference between the inner and outer peripheral surfaces, and improve its durability and reliability.

Therefore, as shown in FIGS. 1 and 2, the inner peripheral portion from both axial ends of the rotor 4 to both magnetic poles of the permanent magnet 9 at right angles to the other inner peripheral portions is made uniform with respect to the other inner peripheral portions. The thin portion 4a is formed into a thin portion 4a, the thin portion 4a is positioned at a connection portion with the thick inner peripheral portion 4b to form the groove 12 having a trapezoidal cross section, and the groove 12 is formed into a similar shape to the groove 12. Copper ring 13
Is formed and attached integrally. That is, a part of the rotor 4 located outside in the axial direction of the rotor with respect to each groove 12 is cut off so that the outer side wall of each groove 12 in the axial direction of the rotor is formed lower than the inner side wall. The copper ring (13) provided in the above is formed to have a larger heat radiation open area than at least the area formed by connecting the opening edges of the grooves (12). Specifically, as shown in FIG. 2, the copper ring 13 is formed such that the inner peripheral surface 13a on the permanent magnet 9 side is an inclined surface connecting the thin portion 4a of the rotor 4 and the thick inner peripheral portion 4b. To be done. That is, the inner peripheral surface 13a formed as an inclined surface also serves as a part of the end surface 13b of the copper ring 13. As a result, the heat radiation surface area of the copper ring 13 in contact with the air is expanded, the heat radiation amount of the rotor 4 and the copper ring 13 is increased, and the thermal deformation of the rotor 4 and the copper ring 13 and the peeling of the copper ring 13 are suppressed. Like Moreover, since both sides of the copper ring 13 are sandwiched between the side walls of the groove 12, the copper ring 13 is prevented from falling off from the groove 12 due to thermal expansion and contraction. As described above, according to the present embodiment, it is possible to prevent the copper ring 13 that generates heat from falling off due to thermal expansion and contraction and improve the heat dissipation.

As another embodiment, as shown in FIG. 3, the copper ring 13 is formed in a rectangular cross section, and the inner peripheral surface of the copper ring 13 is formed.
One of the end surface 13a and the end surface 13b may be opened to the outside to increase the heat dissipation area. Further, as shown in FIG. 4, the groove 12 is formed in a long rectangular shape on both end sides of the rotor 4 and the groove 12 is formed. The copper ring 13 integrally attached to the above may be formed in an L-shaped cross section to further increase the heat dissipation surface area.

As a method of integrating the copper ring 13 with the groove 12, after depositing copper, a method of machining into the above-mentioned shape,
A method of forming a slit in the axial direction of the copper ring 13 and, as shown in FIG. 5, a joint portion 13c, 13d which allows the copper ring 13 to be contracted and expanded in diameter so as to be compatible with fitting property and thermal expansion.
The method of forming the is adopted.

[Effects of the Invention] As is clear from the above description, according to the present invention, since the good conductor has a wide heat dissipation open area, the temperature concentrated on the good conductor during braking can be effectively dissipated. Since both sides of the good conductor are sandwiched by the side walls of the groove, it is possible to prevent the good conductor from falling out of the groove due to thermal expansion and contraction. Therefore, the durability and reliability of the eddy current retarder are improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of the present invention, and FIG.
FIG. 4 to FIG. 4 are enlarged views of essential parts showing a copper ring according to the present invention, FIG. 5 is a detailed view of essential parts of the copper ring, and FIG. 6 is a sectional view showing a conventional eddy current retarder. FIG. 8 is a schematic diagram showing the generation state of eddy currents and magnetic circuits, and FIG. 8 is a schematic diagram showing the inner peripheral surface of the rotor. In the figure, 1 is an eddy current retarder, 2 is a rotary shaft, 4 is a rotor, 6 is a stator, 9 is a permanent magnet, 12 is a groove, and 13 is a copper ring as a good conductor.

Claims (1)

[Scope of utility model registration request] 1. A drum-shaped rotor made of a ferromagnetic material is provided on a rotating shaft, a stator having a permanent magnet is provided inside the rotor so as to be movable toward and away from each other, and an inner peripheral surface of the rotor is arranged along a circumferential direction thereof. In the eddy current retarder in which two grooves are provided in parallel at a predetermined interval and a good conductor is provided in these grooves, a part of the rotor located outside the axial direction of the rotor with respect to each groove is The outer side wall of each groove in the axial direction of the rotor was cut to be lower than the inner side wall, and the heat dissipation open area of the good conductor provided in the groove was made larger than at least the area formed by connecting the opening edges of the groove. An eddy current retarder characterized in that