JP2570565Y2 - Cooling structure of brake drum of eddy current type reduction gear - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current speed reducer mounted on a large vehicle for assisting a friction brake, and more particularly to a cooling structure of a braking drum of an eddy current speed reducer having improved cooling performance against heat generated during braking. Things.

[0002]

2. Description of the Related Art In an eddy current type speed reducer disclosed in Japanese Patent Application Laid-Open No. 1-234043, a magnet support ring is axially slidably supported on a magnet guide frame projecting into a brake drum.
A large number of permanent magnets facing the inner peripheral surface of the brake drum are coupled to the magnet support ring so that the polarities are alternately different in the circumferential direction.
When continuous braking is performed during high-speed running of the vehicle, particularly, the inner peripheral surface of the braking drum becomes hot, so that the strength of the braking drum decreases,
The braking drum may be thermally deformed or cracked.

In order to cool 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 set to the central axis of the brake drum. , The 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, since the gap between the inner peripheral surface of the braking drum, which generates a large amount of heat, and the permanent magnet (actually, the outer peripheral surface of the magnet guide frame) is narrow, there is no active air flow in the gap, and cooling is not performed. Poor.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the purpose of the present invention is to increase the cooling effect by actively sending air to the inner peripheral surface of the braking drum, and to reduce the abnormal temperature rise of the braking drum. An object of the present invention is to provide a cooling structure of a braking drum of an eddy current type reduction gear, which suppresses the eddy current.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a brake drum connected to a rotating shaft,
A cylindrical magnet guide frame made of a non-magnetic material disposed inside the braking drum; a ferromagnetic plate coupled to a number of openings provided at equal intervals in a circumferential direction in the magnet guide frame; An eddy current type speed reducer having a magnet support ring supported inside and having a permanent magnet opposed to each of the ferromagnetic plates and having a polarity alternately different in a circumferential direction, the magnet being supported by the rotating shaft. A windmill is configured with a cross section of a spoke extending radially from the boss portion as an airfoil, and at a connection portion between a distal end portion of the spoke and a base end portion of the braking drum, outside air is supplied from the windmill to an inner peripheral surface of the braking drum. A guiding conical surface is provided, and with the rotation of the braking drum, an airflow from the base end side of the braking drum to the distal end side of the braking drum through a gap between the inner peripheral surface of the braking drum and the outer peripheral surface of the magnet guide frame. It is characterized by causing.

[0006]

According to the present invention, a windmill is formed by using spokes connecting the boss portion and the braking drum as blades, and the windmill sucks air from the base end side of the braking drum, thereby forming a gap between the inner peripheral surface of the braking drum and the permanent magnet. To cool the inner peripheral surface of the brake drum and discharge it to the tip side of the brake drum.

[0007]

FIG. 4 is a side sectional view of an eddy current type speed reducer for a vehicle having a cooling structure for a braking drum 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 end wall of the brake drum 7 of the parking brake and the flange 9a integral with the boss 9 of the brake drum 13 of the speed reducer are overlaid on the mounting flange 5 and fastened with a plurality of bolts 10 and nuts 10a.

The brake drum 13 is supported by a number of spokes 12 extending radially from the boss 9. For this reason, the tip of the spoke 12 is connected to the base 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.

A cylindrical magnet guide frame 18 having an inner space with a box-shaped cross section is disposed inside the braking drum 13 made of an electric conductor. The magnet guide frame 18 is fixed by bolts 32 and 33 to a frame plate 31 having a reinforcing rib 31a externally fitted and fixed to the projecting wall 2a of the gear box 2.

The magnet guide frame 18 may be formed by connecting an annular end wall plate to both ends of an outer cylinder and an inner cylinder. The illustrated magnet guide frame 18 is a left half portion made of a material such as ordinary iron. A cylindrical frame portion 18a having a U-shaped cross section and a cylindrical frame portion 18b having an inverted L-shaped cross section in the right half made of a non-magnetic material such as aluminum are connected by a number of bolts 14. Is done.

A large number of openings are provided in the outer cylindrical portion of the magnet guide frame 18 facing the inner circumferential surface of the braking drum 13, that is, the peripheral wall of the frame portion 18b at equal intervals in the circumferential direction, and a ferromagnetic plate (pole piece) is provided in each opening. ) 21 is fitted and fixed. Actually, when the frame portion 18b 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 ring 19 connected to an end of a rod 17 projecting from a piston fitted into the cylinder to the inner space of the magnet guide frame 18. The magnet support ring 19 is the magnet guide frame 18
Is supported in the inner space so as to be movable in the axial direction. Magnet support ring 1
9, a permanent magnet 20 facing each ferromagnetic plate 21
Are connected with the polarity alternately different in the circumferential direction.

During the braking operation, the magnet support ring 19 is protruded by the actuator through the rod 17 into the brake drum 13 as shown in the drawing. The rotating braking drum 13 is transmitted through the ferromagnetic plate 21 from the permanent magnet 20 and the braking drum 1
When traversing the magnetic field reaching the inner peripheral wall of No. 3, an eddy current is generated in the braking drum 13, and the braking drum 13 receives a braking torque.
The braking drum 13 generates heat due to the eddy current, and is cooled by air directly or by the cooling fin 13a.

According to the present invention, in order to effectively cool the inner peripheral surface of the brake drum 13 which generates the most heat, the spokes 12 connecting the brake drum 13 and the boss 9 are used.
The wind turbine 51 for sending air from the base end portion of the braking drum 13 to the inner peripheral surface of the braking drum 13 is configured to have an airfoil cross section. As shown in FIG. 1, a conical wall 43 is formed at the base end of the braking drum 13, and a number of spokes 12 are integrally formed between the wall 43 and the boss 9 at equal circumferential intervals. Join.

As shown in FIG. 2, each of the plate-shaped spokes 12
Is inclined or twisted with respect to the center axis of the boss portion 9, so that air flows from the base end of the brake drum 13 through the spokes 12 to the outside in the rotation direction y of the brake drum 13. Inner surface 13b of the braking drum 13
Lead to. As shown in FIG. 3, each spoke 12 has a boss 9
It is preferable to bend in the direction opposite to the rotation direction y in accordance with the distance from the brake drum 13 to the braking drum 13.

As shown in FIG. 1, a cylindrical body 41 is fitted to cooling fins 13a disposed at equal intervals in the circumferential direction on the outer peripheral surface of the braking drum 13, and a closed cross-section ventilation passage is provided between the cooling fins 13a. Section 42. The cylindrical body 41 has an axial dimension longer than that of the brake drum 13 and protrudes toward the distal end side (leftward) of the brake drum 13. A flange 18c is formed on the outer peripheral surface of the magnet guide frame 18, the outer peripheral edge of the flange 18c is brought close to the inner peripheral surface of the cylindrical body 41, and a ventilation path 45 is formed between the flange 18c and the tip wall of the braking drum 13. And communicates with the ventilation path 42.

According to the present invention, when the braking drum 13 rotates in the direction of arrow y, the wind turbine 5
1, the air is sucked from the base end side of the braking drum 13 and flows along the conical surface 44 of the wall portion 43.
3 is sent to the gap between the inner peripheral surface 13b and the ferromagnetic plate 21 to efficiently cool the inner peripheral surface 13b of the braking drum 13. The air that has cooled the inner peripheral surface 13b of the braking drum 13
The air flows through the air passage 45 to the left end of the air passage 42, and flows out to the right end of the air passage 42 while cooling the outer peripheral surface of the braking drum 13, the cooling fin 13 a, and the inner peripheral surface of the cylindrical body 41.

According to the present invention, the cooling performance is sufficiently exhibited without providing the ventilation passage 42 on the outer peripheral wall of the braking drum 13. For this reason, when the leading end side of the braking drum 13 cannot be sufficiently opened outward, the inner peripheral surface 13b of the braking drum 13
The cooling performance is further improved by guiding the cooled air to the ventilation passage 42 having a closed cross section on the outer peripheral side of the braking drum 13.

[0018]

As described above, the present invention provides a brake drum connected to a rotating shaft, a cylindrical magnet guide frame made of a non-magnetic material disposed inside the brake drum, and a circumferentially extending magnet around the magnet guide frame. A ferromagnetic plate coupled to a number of openings provided at equal intervals in the direction, and a permanent magnet supported inside the magnet guide frame and facing each of the ferromagnetic plates and having polarities alternately different in the circumferential direction. In the eddy current type speed reducer provided with a magnet support ring, a windmill is formed with a cross section of a spoke radially extending from a boss supported by the rotating shaft as an airfoil, and a tip end of the spoke and a brake drum are provided. A coupling portion with a base end portion is provided with a conical surface that guides outside air from the windmill to the inner peripheral surface of the brake drum, and the inner peripheral surface of the brake drum is arranged from the proximal end side of the brake drum with the rotation of the brake drum. Through the gap between the outer peripheral surface of the magnet guide frame Since it is intended to produce an air flow toward the distal end side of the moving drum, the following effects can be obtained.

The inner peripheral surface of the braking drum that generates the most heat is
The cooling air is efficiently cooled by the air sent from the windmill, and a reduction in the strength and thermal deformation of the braking drum are suppressed.

In other words, fresh outside air can be introduced into the inner peripheral surface of the braking drum where the temperature is highest, and the cooling effect can be enhanced.

Since the inner peripheral surface of the brake drum and the outer peripheral surface of the guide frame are smooth and provided with a conical surface as a wind guide path at the base end side of the brake drum, the magnet inside the guide frame is connected to the brake drum. The airflow to the gap between the inner peripheral surface of the braking drum and the outer peripheral surface of the guide frame can be smoothed while satisfying the requirement of increasing the braking ability by approaching the inner peripheral surface of the guide frame.

Since the spokes of the conventional brake drum are configured as blades, the dimensions of the brake drum do not change.
Cost burden is reduced.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a cooling structure of a braking drum according to the present invention.

FIG. 2 is a plan sectional view taken along line 2A-2A in FIG. 1, showing spokes supporting the braking drum expanded in a circumferential direction.

FIG. 3 is a side view of a cooling structure of the braking drum.

FIG. 4 is a front cross-sectional view of the overcurrent type reduction gear having the brake drum cooling structure according to the present invention.

[Explanation of symbols]

9: Boss part 12: Spoke 13: Brake drum 13
a: cooling fin 13b: inner peripheral surface 18: magnet guide frame
18c: Flange 41: Cylindrical body 42, 45: Ventilation path 44: Conical surface 51: Windmill

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masayuki Sano 3- 25-1, Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Isuzu Motor Co., Ltd. Kawasaki Plant (56) References JP-A-56-133393 (JP, A) Actually open Hei 2-65087 (JP, U) Actually open 1979-180885 (JP, U)

Claims (2)

(57) [Scope of request for utility model registration] 1. A brake drum connected to a rotating shaft, a cylindrical magnet guide frame made of a nonmagnetic material disposed inside the brake drum, and a plurality of magnet guide frames provided at regular intervals in a circumferential direction on the magnet guide frame. A ferromagnetic plate coupled to the opening; and a magnet support ring supported inside the magnet guide frame and supporting the permanent magnet so as to face each of the ferromagnetic plates and to have polarities alternately different in the circumferential direction. In the eddy current type speed reducer, a windmill is configured with a cross section of a spoke radially extending from a boss portion supported by the rotation shaft as an airfoil, and a connecting portion between a tip end of the spoke and a base end of the braking drum is formed. A conical surface that guides outside air from the wind turbine to the inner peripheral surface of the brake drum, and the inner peripheral surface of the brake drum and the outer peripheral surface of the magnet guide frame from the base end side of the brake drum as the brake drum rotates. To the tip of the braking drum through the gap between Characterized in that to produce a flow,
Cooling structure of the braking drum of the eddy current type reduction gear. 2. A cylindrical body is externally fitted on the outer peripheral side of a number of cooling fins arranged at equal intervals in the circumferential direction on the outer peripheral surface of the braking drum to form an axial ventilation passage. 2. The air flow path according to claim 1, further comprising: a flange that approaches an end of the cylindrical body, and a radial ventilation path that communicates the air gap with the ventilation path between the flange and a tip wall of the braking drum. 3. Cooling structure of the braking drum of the eddy current type speed reducer.