JPH10146041A - Eddy current decelerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the cooling effect and prevent the overheat of a braking drum by sending air positively to the inside periphery of the braking drum. SOLUTION: The base of the braking drum 13 consisting of a conductor is coupled with the tip of the spoke 12 extending radially from the boss part 9 coupled with a rotary shaft 4, and a magnet support cylinder 19 to couple a plurality of magnets 20 opposed to the inside periphery of a braking drum 13 is arranged inside the braking drum 13. This eddy current decelerator is provided with a longitudinal air passage 41 inside the spoke 12. This is provided with an air intake 41b lead to the base end of the air passage 41 and a guide vane 43 for leading air to the air intake 41b at the external surface of the base end of the spoke 12. This is provided with an air nozzle which leads to the tip of the air passage 41 and besides blows out air to the tip of the braking drum 13 via the space between the inside periphery of the braking drum 13 and the magnet supporting cylinder 19, at the inside periphery of the tip of the spoke 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current reduction device mounted on a large vehicle to assist a friction brake, and more particularly to an eddy current reduction device for improving cooling performance during braking.

[0002]

2. Description of the Related Art In an eddy current reduction device disclosed in Japanese Patent Application Laid-Open No. 1-234043, a magnet support tube is slidably supported in an axial direction by a guide tube projecting into a brake drum. A number of magnets facing the surface are coupled to the magnet support tube such that the polarities alternately differ in the circumferential direction. When continuous braking is performed while the vehicle is running at high speed, the inner peripheral surface of the braking drum becomes hot, so that the strength of the braking drum is reduced, and the braking drum may be thermally deformed or cracked.

In order to enhance the cooling performance of the brake drum, the conventional brake drum is provided with cooling fins protruding radially outward on the outer peripheral surface at equal intervals in the circumferential direction, and the longitudinal direction of the cooling fin is adjusted in the longitudinal direction of the brake drum. Since it is inclined with respect to the central axis, air flows through the space between the cooling fins from one end to the other end of the brake drum as the brake drum rotates. However, there is no active air flow on the inner peripheral surface of the braking drum that generates a large amount of heat,
Since the gap with the outer peripheral surface of the magnet support cylinder (actually, the guide cylinder) is narrow, cooling performance is poor.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an eddy current which actively sends air to an inner peripheral surface of a braking drum to enhance a cooling effect and prevent overheating of the braking drum. It is to provide a reduction gear.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a base end of a braking drum made of a conductor is connected to a tip end of a spoke extending radially from a boss connected to a rotating shaft. In an eddy current reduction device in which a magnet support cylinder that couples a plurality of magnets facing the inner peripheral surface of the braking drum is disposed inside the braking drum, a longitudinal air flow path is provided inside the spoke, An air inlet connected to the base end of the air flow path and guide vanes for guiding air to the air inlet are provided on the outer surface of the base end of the spoke, and a front end of the air flow path is connected to an inner surface of a tip part of the spoke. And an air outlet for blowing air to the tip of the brake drum along the inner peripheral surface of the brake drum.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When a magnet support cylinder of an eddy current reduction device is moved to a braking position, a magnetic circuit passes through a magnet, a ferromagnetic plate, a braking drum, a ferromagnetic plate, a magnet, and a magnet support cylinder. A braking torque is generated by the eddy current. During the braking operation of the eddy current reduction device, the inner peripheral surface of the braking drum becomes hot due to the eddy current generated in the braking drum and the electric resistance of the braking drum. When the braking torque increases, the amount of heat generated by the braking drum also increases, and the magnetic flux passing through the magnet support tube decreases due to radiant heat from the braking drum, and the braking torque decreases.

In order to protect the brake drum and the magnet support cylinder, it is necessary to cool the inner peripheral surface of the brake drum. Although the cooling fin has a cooling effect on the outer peripheral surface of the braking drum,
Heat remains on the inner peripheral surface of the brake drum, which is the hottest.

In the present invention, an air flow path is provided inside a spoke supporting the braking drum, and a guide vane is provided at an inlet of the air flow path, that is, an air intake. Blows air into the inside to suppress the abnormal rise in temperature of the brake drum.

[0009]

1 is a side sectional view of a permanent magnet type eddy current reduction device provided with a brake drum cooling structure according to the present invention.
A mounting flange 5 is spline-fitted to an output rotary shaft 4 which is supported by a bearing 3 on an end wall of a gear box 2 of the transmission and protrudes from the end wall, and is fastened by a nut 6 so as not to come off. The mounting drum 5 has a braking drum 7 for the parking brake.
And the boss 9 of the braking drum 13 of the eddy current reduction device
And the integral flange 9a are overlapped, and a plurality of bolts 1
0 and the nut 10a.

The brake drum 13 is supported by a number of spokes 12 extending radially from the boss 9. Therefore, the distal end of the spoke 12 is connected to the proximal end of the braking drum 13 by welding. A large number of cooling fins 13a are provided on the outer peripheral wall of the braking drum 13 at equal intervals in the circumferential direction.

Inside the braking drum 13 made of an electric conductor, a cylindrical guide tube 18 having an inner space with a rectangular cross section is provided. The guide cylinder 18 includes a frame plate 31 having a reinforcing rib 31a externally fitted and fixed to the protruding wall 2a of the gear box 2, a bolt 32,
33 fixed. The guide tube 18 may be formed by connecting an annular end wall plate to both ends of the outer tube and the inner tube. However, the illustrated guide tube 18 has a U-shaped cross section of a left half made of a material such as ordinary iron. A cylindrical portion 18a is formed by connecting a plurality of bolts 14 to a cylindrical portion 18b having a right-half inverted L-shaped cross section of a right half portion made of a nonmagnetic material such as aluminum.

A large number of openings are provided at equal intervals in the circumferential direction on the outer cylindrical portion of the guide cylinder 18 facing the inner peripheral surface of the braking drum 13, that is, on the peripheral wall of the cylindrical portion 18b. 21 is fitted and fixed. Actually, the tube part 1
When 8b is cast from aluminum, the ferromagnetic plate 21 is cast. A plurality of actuators (not shown) are supported on the frame plate 31 at equal intervals in the circumferential direction. The actuator has a magnet support cylinder 19 connected to an end of a rod 17 projecting from a piston fitted into the cylinder to the inner space of the guide cylinder 18. The magnet support cylinder 19 is supported by the inner space of the guide cylinder 18 so as to be movable in the axial direction. On the outer peripheral surface of the magnet support cylinder 19,
A large number of magnets 20 facing each ferromagnetic plate 21 are alternately coupled in the circumferential direction with different polarities.

During the braking operation, the magnet support cylinder 19 is protruded by the actuator through the rod 17 into the brake drum 13 as shown in the drawing. When the rotating brake drum 13 crosses the magnetic field from the magnet 20 through the ferromagnetic plate 21 to the brake drum 13, an eddy current is generated in the brake drum 13 and the brake drum 13 receives a braking torque. The braking drum 13 generates heat due to the eddy current, and is directly or cooled.
Cooled by air at a.

In the present invention, the braking drum 1 which generates the most heat is used.
3 to effectively cool the inner peripheral surface 13b (FIG. 2)
A longitudinal air flow path 41 is provided inside the spoke 12 supporting the braking drum 13. On the outer surface of the base end of the spoke 12, an air intake 41b connected to the base end of the air flow path 41 and guide vanes 43 for guiding air to the air intake 41b are provided. An air outlet 41a is provided on the inner surface of the distal end portion of the spoke 12 and communicates with the distal end of the air flow path 41 and blows air to the distal end portion of the braking drum 13 through the gap between the braking drum 13 and the magnet support cylinder 19 or the guide cylinder 18. .

As shown in FIGS. 2 and 3, an inclined surface 42 inclined with respect to the rotating shaft 4 is formed at the lower end of the spoke 12 and the outer end of the boss 9. The air passage 41 is curved inside the spoke 12. That is, the proximal end of the air flow path 41 extends radially inward and opens to the inclined surface 42 at the proximal end of the spoke 12 to form the air intake 41b. The front end portion of the air passage 41 has a passage area gradually reduced, and the braking drum 13
The air inlet 41b is preferably formed in a nozzle shape. The guide blades 43 made of a thin plate protruding in the axial direction from the inclined surface 42 are integrally formed by casting when the boss 9 and the spokes 12 are cast. The guide blade 43 is provided for the braking drum 13.
In the rotation direction (arrow x), is disposed behind the air intake 41b.

According to the present invention, as described above, when the braking drum 13 rotates in the direction of the arrow x, the air hitting the guide blades 43 enters the air passage 41 from the air inlet 41b. The flow velocity gradually increases as the flow path area decreases, and the inner peripheral surface 13b of the braking drum 13 and the magnet support tube, in the illustrated embodiment, the guide tube 1
8 flows to the tip of the brake drum 13 through the gap 23 between the outer peripheral wall of the brake drum 8 and the inner peripheral surface 13 b of the brake drum 13.

Although the embodiment of the permanent magnet type eddy current reduction device has been described above, the present invention is not limited to this, and can be applied to an electromagnet type eddy current reduction device.

[0018]

As described above, according to the present invention, an air flow path for sucking air and blowing air into the brake drum is provided inside the spokes supporting the brake drum, so that the inner peripheral surface of the brake drum and the magnet support are provided. Air can be blown into the gap between the cylinder and the outer peripheral surface of the guide cylinder to cool the inner peripheral surface of the brake drum.

The inner peripheral surface of the braking drum, which generates the largest amount of heat, is efficiently cooled, so that strength reduction and thermal deformation due to a temperature difference between the inner and outer peripheral surfaces of the braking drum are suppressed.

Since the radiant heat from the braking drum is reduced, the magnet support cylinder and the magnet are protected, and the reduction of the braking torque due to the reduction of the magnetic flux is suppressed.

By forming the air flow passage inside the spokes of the conventional braking drum, the spokes can be reduced in weight without impairing the strength of the spokes, and the cost burden can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an eddy current reduction device according to the present invention.

FIG. 2 is an enlarged side sectional view showing a main part of the eddy current reduction device.

FIG. 3 is a front view of a main part of the eddy current reduction device.

[Explanation of symbols]

2: gear box 2a: protruding wall 3: bearing 4: rotating shaft 5:
Mounting flange 7: braking drum 9: boss 9a: flange 12: spoke 13: braking drum 13a:
Cooling fin 18: Guide tube 18a: Tube portion 18b:
Tube part 19: Magnet support tube 20: Magnet 21: Ferromagnetic plate 31: Frame plate 31a: Reinforcement rib 41: Air flow path
41a: Air outlet 41b: Air inlet 43: Guide vane

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Eiji Okumura, Inventor No. 8 Fujisawa-shi, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. In-house (72) Inventor Shuhisa Okuda Eighth shelf, Fujisawa-shi, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd.

Claims (2)

[Claims] 1. A magnet for connecting a base end of a braking drum made of a conductor to a tip end of a spoke extending radially from a boss connected to a rotation shaft, and connecting a plurality of magnets facing an inner peripheral surface of the braking drum. In an eddy current reduction device in which a support cylinder is disposed inside a braking drum, a longitudinal air flow path is provided inside the spoke, and the spoke is connected to a base end of the air flow path on an outer surface of a base end portion of the spoke. An air inlet and guide vanes for guiding air to the air inlet are provided, and are connected to the tip of the air flow path on the inner surface of the tip of the spoke and to the tip of the brake drum along the inner peripheral surface of the brake drum. An eddy current reduction device comprising an air outlet for blowing air. 2. The eddy current reduction device according to claim 1, wherein the magnet is one of a permanent magnet and an electromagnet.