JPH0580180U - Wind loss reduction structure of eddy current type speed reducer - Google Patents

Abstract

(57) [Abstract] [Purpose] With a simple structure, the air flow due to the cooling fins of the braking drum during non-braking is suppressed, and the windage loss is reduced. [Structure] A large number of permanent magnets 24 are coupled to the outer peripheral wall of the magnet support ring 14 at equal intervals in the circumferential direction, and the polarities of the outer ends are alternately different in the circumferential direction. The magnet support ring 14 is fixed to the fixed frame 1 such that the magnet support ring 14 can be moved between a braking position protruding into the braking drum 7 coupled to the rotating shaft 1 and a non-braking position retracting from the braking drum 7.
Support 0. The base ends of a plurality of rods 31 curved in a C shape are connected to the end wall of the magnet support ring 14, and the tip ends of the rods 31 are connected to a cylindrical cover 32 that covers the outer peripheral side of the braking drum 7. During non-braking, the cover 32 covers the cooling fins 8 provided on the outer peripheral wall of the braking drum 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention reduces the windage loss due to the cooling fins of the eddy current type speed reducer that assists the friction brake of a large vehicle, etc., especially the cooling drum of the braking drum that is constantly rotated by being connected to the output rotary shaft of the transmission, thereby reducing the fuel consumption of the engine. The present invention relates to an improved structure for reducing wind loss of an eddy current type speed reducer.

[0002]

[Prior Art]

 As disclosed in Japanese Patent Application No. 1-218498, an eddy current type speed reducer is provided with a large number of permanent magnets (hereinafter simply referred to as magnets) on the outer peripheral wall of a magnet support ring at equal intervals in the circumferential direction and at the outer end. The magnet support ring is supported by a fixed frame that protrudes inside the braking drum that is connected to the rotating shaft so that the polarities are alternately different from each other. The magnet support ring is braked during braking. When protruding into the drum, the magnet of the magnet support ring approaches the inner peripheral surface of the braking drum, and when the rotating braking drum crosses the magnetic field from the magnet, the braking drum receives braking torque based on eddy current. When the magnet support ring is pulled out from the inside of the braking drum during non-braking, the magnet does not exert a magnetic field on the braking drum, and the braking drum receives no braking torque.

In the above-mentioned eddy current type speed reducer, in order to dissipate the heat due to the eddy current generated during braking, the braking drum is provided with a large number of cooling fins on the outer peripheral wall. However, since the braking drum rotates even during non-braking, the windage loss of the cooling fins cannot be ignored.

In order to completely eliminate the windage loss of the cooling fins, it is preferable to provide a clutch between the braking drum and the rotating shaft to interrupt the clutch when not braking and stop the braking drum. However, if a clutch is provided, the structure becomes complicated, the shape becomes large, the weight of the rotating body increases, it becomes difficult to mount it on the vehicle, and it is necessary to consider the reliability of the clutch against heat. Problems arise.

[0005]

[Problems to be solved by the device]

 In view of the above problems, an object of the present invention is to provide a wind loss reduction structure of an eddy current type speed reducer having a simple configuration, which reduces wind loss by suppressing the flow of air due to cooling fins when not braking. It is in.

[0006]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the structure of the present invention, a large number of permanent magnets are coupled to the outer peripheral wall of the magnet supporting ring so that the polarities of the outer ends are alternately different in the circumferential direction and are coupled to the rotating shaft. In an eddy current type speed reducer in which a magnet support ring is supported by a fixed frame so as to be movable between a braking position protruding inside the braking drum and a non-braking position retracting from the braking drum, a plurality of C-shaped curved parts are used. The base end of the rod is connected to the end wall of the magnet support ring, the front end of the rod is connected to the cylindrical cover that covers the outer peripheral side of the braking drum, and the cooling fin provided on the outer peripheral wall of the braking drum by the non-braking cover is connected. To cover.

[0007]

[Action]

 The cylindrical cover covering the outer peripheral side of the braking drum is coupled to the end of the magnet support ring by a plurality of rods curved in a C shape. When the magnet support ring retracts from the inside of the braking drum, the cover moves axially together with the magnet support ring to cover the outer peripheral side of the braking drum. Therefore, the air volume sent by the cooling fins of the constantly rotating braking drum is suppressed by the cover, and the air flow is stabilized by the cover, so wind loss is reduced and noise is suppressed.

During braking, if the magnet support ring projects into the inside of the braking drum, the cover moves in the same direction and retreats from the outer peripheral side of the braking drum, so the air volume due to the cooling fins increases and the heat radiation of the damping drum increases. Does not interfere.

[0009]

【Example】

 FIG. 1 is a side sectional view of an eddy current type speed reducer having a windage loss reducing structure according to the present invention. The eddy current type speed reducer is arranged, for example, at the rear end of a transmission for a vehicle, and has an annular shape having a braking drum 7 connected to an output rotary shaft 1 of the transmission and an inner space having a rectangular cross section. It is composed of a fixed frame 10 and a magnet support ring 14 that can project into the inner space of the fixed frame 10 into the braking drum 7. A mounting flange 2 is spline-fitted to the end of the output rotary shaft 1 of the transmission, and is fastened by a nut 1a so as not to come off. An end wall of a braking drum 3 of a known parking brake and a flange portion 5a of a braking drum 7 of a speed reducer are superposed on the mounting flange 2 and are connected to a plurality of bolts 4 and nuts.

A plurality of spokes 6 extending radially outward at equal intervals in the circumferential direction are coupled to a cylindrical boss 5 that is integral with the flange portion 5a. The outer edge of the spoke 6 is joined to the edge of the braking drum 7 which is a conductor. The braking drum 7 is provided on its outer peripheral surface with a large number of cooling fins 8 arranged at equal intervals in the circumferential direction.

A plurality of (preferably three) fluid pressure actuators (not shown) are supported on the end wall of the fixed frame 10 at equal intervals in the circumferential direction. A magnet support ring 14 is coupled to the end of a rod extending from a piston fitted in the actuator cylinder. The fixed frame 10 is composed of an annular frame portion 10a made of a magnetic material and having a C-shaped cross section, and a non-magnetic frame portion 10b made of a non-magnetic material and having an inverted L-shaped cross section, which are connected by a large number of bolts. A large number of ferromagnetic plates (pole pieces) 15 corresponding to the respective magnets 24 are coupled to the openings formed in the cylindrical wall of the frame portion 10b projecting inside 7.

As shown in FIG. 3, the magnet support ring 14 is axially slidably supported inside the rectangular frame of the fixed frame 10. Specifically, the magnet support ring 14 is slidably and non-rotatably fitted onto the inner cylinder of the frame portion 10a. A large number of magnets 24 are coupled to the outer peripheral surface of the magnet support ring 14 at equal intervals in the circumferential direction and in such a manner that the polarities thereof are alternately different by one (or two by two) in the circumferential direction.

According to the present invention, the cylindrical cover 32 covering the cooling fins 8 on the outer periphery of the braking drum 7 moves axially together with the magnet support ring 14 in order to reduce the wind loss during non-braking. Arranged as possible. Therefore, the base ends 31a of a large number of rods 31 curved in a U-shape or a C-shape pass through the end wall of the fixed frame 10 to face the inner space and are connected to the magnet support ring 14. The tip 31b of the rod 31 extends along the outer surface of the cover 32, penetrates the mounting piece 33 projecting radially outward from the edge of the cover 32, and is fastened by a nut 34. Preferably, the cover 32 is formed of a thin metal plate or the like, and the rod 31 which also serves as a reinforcement of the cover 32 is joined to the outer peripheral surface of the cover 32 by an appropriate means.

Next, the operation of the windage loss reducing structure of the eddy current type speed reducer according to the present invention will be described. During braking shown in FIG. 1, the magnet support ring 14 projects into the braking drum 7, and each magnet 24 penetrates the ferromagnetic plate 15 to exert a magnetic field on the inner peripheral surface of the braking drum 7. At this time, the cover 32 supported by the rod 31 moves to the right side of the braking drum 7 and releases the cooling fin 8. As the rotating braking drum 7 traverses the magnetic field from the magnet 24, the braking drum 7 experiences braking torque due to eddy currents. As shown in FIG. 3, during braking, each magnet 24 forms a magnetic circuit W between the magnet support ring 14 and the braking drum 7.

The braking drum 7 is heated by the eddy current and becomes high in temperature. However, since the braking drum 7 is provided with the cooling fin 8 and the cover 32 is retracted, the heat radiation from the braking drum 7 and the air sent to the inner and outer peripheral surfaces of the braking drum 7 by the cooling fin 8 are effective. To be cooled.

When the magnet support ring 14 is pulled to the left by the above-described fluid pressure actuator in FIG. 1 during non-braking, the magnet 24 does not face the ferromagnetic plate 15, and the outer cylinder of the frame portion 10 a made of a magnetic material is used. To face. At the same time, the rod 31 pulls the cover 32 leftward by the stroke s to cover the cooling fin 8 as shown by the chain line in FIG. Since the amount of air passing through the inside of the cover 32 is suppressed and the turbulence of the air blown through the cover 32 is suppressed, the windage loss due to the rotation of the braking drum 7 and the cooling fins 8 is reduced, and the noise is also reduced.

[0017]

As described above, according to the present invention, the base end of the rod curved in a C shape is connected to the end wall of the magnet supporting ring, and the tip of the rod is connected to the cylindrical cover covering the outer peripheral side of the braking drum. Since the non-braking cover covers the cooling fins provided on the outer peripheral wall of the braking drum, the amount of air passing through the inside of the cover is restrained and the turbulence of the air blown through the cover is restrained during non-braking. Therefore, the windage loss due to the rotation of the braking drum and the cooling fin is reduced, and the noise is also reduced. As a result, the fuel efficiency of the engine can be reduced.

Since it is not necessary to provide an expensive clutch having a complicated structure between the braking drum and the rotary shaft, it is possible to avoid an increase in the size of the device, an increase in weight, a decrease in reliability, etc., and to provide the device at a low cost.

During braking, the cover, together with the magnet support ring driven by the hydraulic actuator, automatically retracts from the braking drum, so no special drive source is required.

[Brief description of drawings]

FIG. 1 is a side sectional view of an air loss reduction structure of an eddy current type speed reducer according to the present invention.

FIG. 2 is a side sectional view showing a main part of the windage loss reducing structure.

3 is a front cross-sectional view of the magnet support ring taken along the line 3A-3A in FIG.

[Explanation of symbols]

1: Rotating shaft 7: Braking drum 8: Cooling fin 10:
Fixed frame 14: Magnet support ring 31: Rod 32: Cover

Claims (1)

[Scope of utility model registration request] 1. A braking system, in which a large number of permanent magnets are connected to an outer peripheral wall of a magnet support ring so as to be equally spaced in the circumferential direction and the polarities of the outer ends thereof are alternately different in the circumferential direction, and project into the braking drum connected to a rotary shaft. In the eddy current type speed reducer in which the magnet support ring is supported by the fixed frame so as to be movable to the position and the non-braking position retracted from the braking drum, the base ends of the plurality of rods curved in the C shape are connected to the ends of the magnet support ring. Eddy current deceleration, characterized in that the tip of the rod is connected to a wall of the cylinder with a cylindrical cover that covers the outer peripheral side of the braking drum, and the cooling fin provided on the outer peripheral wall of the braking drum is covered by the non-braking cover. Device wind loss reduction structure.