JP2616592B2 - 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 braking drum of an eddy current speed reducer having improved cooling performance against heat generated during braking. .

[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 cylinder is axially slidably supported by a magnet guide frame projecting into a braking drum.
A large number of permanent magnets facing the inner peripheral wall of the brake drum are coupled to the magnet support cylinder such that the polarity alternates in the circumferential direction.
When continuous braking is performed during high-speed running of the vehicle, the temperature of the braking drum becomes high, so that the strength of the braking drum is reduced, and the braking drum may be thermally deformed or cracked.

In order to cool the brake drum, the conventional brake drum is provided with a large number of fins projecting radially outward on the outer peripheral wall at equal intervals in the circumferential direction, and the longitudinal direction of the fins is aligned with the center axis of the brake drum. , The air flows from one end of the brake drum to the other end through the space between the fins as the brake drum rotates. However, since the space between the fins is open to the outside of the diameter of the braking drum, the air between the fins tends to flow outward due to centrifugal force due to the rotation of the braking drum. The air density in the space between the fins where heat is to be absorbed from the outer peripheral wall of the drum and the fins is coarsened, and the cooling effect is reduced.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to form a closed ventilation path between fins of a brake drum so that air between the fins does not flow out due to centrifugal force. An object of the present invention is to provide a braking drum of an eddy current type speed reducer, in which air is positively introduced into an air passage to enhance a cooling effect.

[0005]

In order to attain the above object, according to the present invention, a rotating drum is connected to a braking drum made of a conductor, and a ring-shaped inner space made of a non-magnetic material and having a rectangular cross section is formed. A magnet guide frame having one end thereof protruding into the brake drum, and having a number of openings formed in an outer peripheral wall of the magnet guide frame facing the inner peripheral surface of the brake drum at equal intervals in the axial direction. A ferromagnetic plate is coupled to the opening, a magnet support cylinder is supported in the inner space of the magnet ratio inner frame so as to be movable in the axial direction, and a polarity facing the ferromagnetic plate is provided on an outer peripheral wall of the magnet support cylinder. In the eddy current type reduction gear device which couples magnets so as to be alternately different in the circumferential direction and generates an eddy current on the braking drum on which the magnet rotates, a large number of radially outwardly projecting outer peripheral walls of the braking drum are provided. Cooling fins are provided at equal intervals in the circumferential direction and An outer ventilation passage having a closed cross section is defined by external fitting, an opening communicating with each ventilation passage is provided at an axial center of the cylindrical body, and an outer edge of each opening has a rotation direction and a radial outside of the braking drum. It is characterized in that it has an airflow protruding plate obliquely projecting toward it.

[0006]

According to the present invention, a large number of closed-section ventilation passages are provided at equal intervals in the circumferential direction on the outer peripheral wall of the braking drum, and air is allowed to flow from the axial center of the ventilation passage to both ends. The brake drum is cooled through the inner wall of the road. Since the ventilation passage has a closed cross section, the air in the ventilation passage does not flow radially outward due to centrifugal force, so that a decrease in the air density is suppressed and the cooling effect is improved.

[0007]

FIG. 4 is a front sectional view of a vehicle eddy current type reduction gear provided with 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. An end wall of the brake drum 7 of the parking brake and a flange 9a integral with the boss 9 of the brake drum 13 of the reduction gear are superimposed on the mounting flange 5, and a plurality of bolts 10 and nuts 10a are provided.
Is concluded.

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 right end of the brake drum 13 by welding. A large number of 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 rectangular cross section is provided inside a braking drum 13 made of an electric conductor.
Are arranged so that the right half of the protrudes. 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 at equal intervals in the circumferential direction on the outer cylindrical portion of the magnet guide frame 18 facing the inner circumferential wall of the braking drum 13, that is, on the circumferential wall of the frame portion 18b, and each opening has a ferromagnetic plate (pole piece). 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 cylinder 19 connected to an end of a rod 17 projecting from a piston fitted into the cylinder to an inner space of the magnet guide frame 18. The magnet support cylinder 19 is a magnet guide frame 18
Is supported so as to be movable in the axial direction. Permanent magnets 20 facing each ferromagnetic plate 21 are alternately connected to the outer peripheral wall of the magnet support cylinder 19 in the circumferential direction so as to have different polarities.

During the braking operation, the magnet support cylinder 19 is protruded into the brake drum 13 via the rod 17 by an actuator (not shown). The rotating braking drum 13 passes through the ferromagnetic plate 21 from the permanent magnet 20 and
When crossing the magnetic field reaching the inner peripheral wall of the vehicle, 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 fin 13a.

As shown in FIG. 1, the present invention relates to a brake drum 1.
The cylindrical body 41 is externally fitted to the fins 13a arranged at regular intervals in the circumferential direction in order to suppress a decrease in the air density near the outer peripheral wall, maintain the heat absorption capacity of the air, and enhance the cooling performance of the brake drum 13. Thus, a ventilation path 42 is formed between the fins 13a.

In the embodiment shown in FIG. 1, the ventilation passages 42 are provided in parallel with the central axis of the brake drum 13 and serve as ventilation means for passing air through the ventilation passages 42. An opening 44 is provided at the center of the body 41 in the axial direction, and the rotation direction y of the braking drum 13 is provided on the outer peripheral side of each opening 44.
A wind drawer 43 is provided that projects obliquely outward toward. In order to make the air flow in the ventilation path 42 smooth,
Is preferably bent into a V shape when viewed from the outer peripheral side.

When the braking drum 13 rotates in the rotation direction y, the air on the outer peripheral side of the cylindrical body 41 hits the air draw plate 43,
The air is introduced to the center of the ventilation path 42 in the axial direction through the opening 44, and flows out to both ends of the ventilation path 42 while cooling the outer peripheral wall of the brake drum 13, the fin 13 a, and the inner peripheral wall of the cylindrical body 41. In this embodiment, even after the rotation of the brake drum 13 is stopped, the hot air in the ventilation passage 42 is discharged to the outside through the opening 44, so that the heat radiation effect is excellent.

In the embodiment shown in FIGS. 2 and 3, the corrugated fin 48 has a peak 48a and a valley 48 formed by corrugating a thin plate on the inner peripheral wall of the cylindrical body 47 and the outer peripheral wall of the braking drum 13.
b is welded to form a ventilation path 53 on the cylindrical body side and a ventilation path 52 on the braking drum side. The ridge line of the peak portion 48 a of the corrugated fin 48 is inclined with respect to the center axis of the braking drum 13. At the axial center of the cylindrical body 47,
A triangular pyramid-shaped air flow plate 45 is cut and raised toward the outer peripheral side of the cylindrical body 47 to form an opening 46 forward in the rotation direction y of the braking drum 13. When the braking drum 13 rotates in the direction of the arrow y, air on the outer peripheral side of the cylindrical body 47 is introduced into the axial center of the ventilation path 53 from the opening 46 and flows to both ends of the ventilation path 53, and the cylindrical body 47 and the corrugated air flow. The fin 48 is cooled.

In this embodiment, the outer peripheral wall of the braking drum 13, the cylindrical body 47 and the corrugated fin 48 are coated with a brazing material in advance, combined with each other and welded in a heating furnace.
Since the assembling process is very simple and the corrugated fin 48 is joined to the braking drum 13 and the cylindrical body 47, even if the thickness of the cylindrical body 47 and the corrugated fin 48 is thin, the rigidity is high and the weight is reduced. Also helps. Corrugated Fin 48
The direction of the ridge line of the peak portion 48a may be parallel to the central axis of the braking drum 13 or may be bent in a V shape. Also, a louver is provided in the corrugated fin 48 to allow a part of the air in the ventilation passage 53 to pass through the ventilation passage 53. 52.

[0018]

According to the present invention, as described above, the braking drum made of a conductor is connected to the rotating shaft, and the magnet guide frame having an annular inner space made of a non-magnetic material and having a rectangular cross section is provided at one end thereof. The magnet guide frame is disposed so as to protrude into the inside of the brake drum, and a number of openings are provided at equal intervals in an axial direction on an outer peripheral wall of the magnet guide frame facing the inner peripheral surface of the brake drum, and a ferromagnetic plate is provided in the openings. The magnet support tube is supported in the inner space of the magnet guide frame so as to be movable in the axial direction, and the magnets are provided on the outer peripheral wall of the magnet support tube such that the polarity facing the ferromagnetic plate is alternately different in the circumferential direction. In the eddy current type speed reducer for generating an eddy current in the brake drum on which the magnet rotates, a large number of cooling fins projecting radially outward on the outer peripheral wall of the brake drum are provided at regular intervals in a circumferential direction. Axial communication with a closed cross-section Since the path is partitioned, openings are provided at the axial center of the cylindrical body to communicate with the ventilation paths, and the edge of each opening is provided with a draft plate that projects obliquely outward in the rotational direction and radially outward of the braking drum. When the brake drum rotates, the air introduced into the opening of the cylindrical body by the airflow plate flows through the ventilation passage to cool the brake drum. Since the ventilation passage has a closed cross section, the air does not flow outward due to the centrifugal force, so the decrease in air density is suppressed, the heat absorption capacity of air is large, and the cooling effect is improved. Is done.

Since the opening for introducing air and the ventilation plate are provided at the axial center of the ventilation passage, the length of the air passage is reduced by half, and the heat absorption capacity of air is also increased in this respect, and the cooling effect is improved. Be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a braking drum according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of a brake drum according to a second embodiment of the present invention.

FIG. 3 is a plan view showing a part of the braking drum developed in a circumferential direction.

FIG. 4 is a front sectional view of an eddy current type reduction gear provided with a braking drum according to the present invention.

[Explanation of symbols]

13: Brake drum 13a: Fin 41, 47: Cylindrical body 42, 52, 53: Ventilation path 43, 45: Winding plate 44, 46: Opening 48: Corrugated fin

 ──────────────────────────────────────────────────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 Tokiko 37-14563 (JP, B1)

Claims (1)

(57) [Claims] 1. A magnet guide frame having a ring-shaped inner space made of a non-magnetic material and having a rectangular cross section, and one end of which projects into the brake drum. The magnet guide frame is provided with a number of openings at regular intervals in the axial direction on an outer peripheral wall of the magnet guide frame facing the inner peripheral surface of the braking drum, and a ferromagnetic plate is coupled to the openings. A magnet support cylinder is supported in the inner space so as to be movable in the axial direction, and a magnet is coupled to the outer peripheral wall of the magnet support cylinder so that the polarity facing the ferromagnetic plate is alternately different in the circumferential direction, and the magnet rotates. In the eddy current type speed reducer for generating an eddy current in the braking drum, a large number of cooling fins protruding radially outward are provided on the outer peripheral wall of the braking drum at regular intervals in the circumferential direction, and the cylindrical body is externally fitted and closed. Defining an axial ventilation passage forming a cross section, An eddy current type, wherein an opening communicating with each ventilation path is provided at the center in the axial direction, and an airflow plate is provided at an edge of each opening so as to project obliquely outward in the rotation direction and radially outward of the braking drum. The braking drum of the reduction gear.