JP2001112237A - Eddy current reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy current reduction gear arranged to enhance ventilation in a brake drum. SOLUTION: The eddy current reduction gear comprises a brake drum 7 coupled with a rotary shaft 1, a nonmagnetic guide tube 18 having a cavity 25 of rectangular cross-section fixed to a nonrotational part, e.g. the chassis, while facing the inside of the brake drum 7, at least one movable magnet supporting cylinder 19, 59 contained in the inner cavity 25 of the guide tube 18, a large number of magnets 20, 60, bonded to the outer circumferential surface of the magnet supporting cylinder 19, 59 at a constant interval in the circumferential direction, and a large number of ferromagnetic plates 21 cast in an outer tubular part 18a facing the magnets 20, 60 of the guide tube 18 wherein a brake force is generated in the brake drum 7 by the fields from the magnets 20, 60 based on the eddy current. A large number of axial grooves 22 are made in the inner circumferential surface 7b of the brake drum 7 facing the outer tubular part 18a at an interval in the circumferential direction.

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 for assisting a friction brake of a large vehicle or the like, and more particularly to an eddy current reduction device for improving the ventilation performance of a braking drum to enhance the cooling performance. It is.

[0002]

2. Description of the Related Art In an eddy current reduction device such as disclosed in Japanese Patent Publication No. Hei 7-118901, a rotating braking drum moves a magnet of a magnet support cylinder from a ferromagnetic plate of a guide cylinder containing the magnet support cylinder. When traversing the magnetic field that passes through the brake drum, a braking force is generated in the brake drum based on the eddy current. Eddy currents turn into heat to heat the braking drum. Cooling fins are provided on the outer peripheral surface of the braking drum so that the braking drum is cooled by the outside air, but the gap between the inner peripheral surface of the braking drum and the guide cylinder is preferably as narrow as possible in terms of braking performance. On the other hand, the amount of air that the outside air passes in the axial direction along the inner peripheral surface of the braking drum is limited. In particular, during braking during high-speed operation of the vehicle, heat due to the eddy current is transmitted not only to the braking drum but also to the guide cylinder, causing a reduction in braking capability.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an eddy current speed reducer in which the ventilation inside the brake drum is improved in view of the above-mentioned problems.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a construction of the present invention comprises a braking drum connected to a rotating shaft and a non-rotating part such as a vehicle body which faces the inside of the braking drum. A guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section, at least one movable magnet support tube housed in the inner space of the guide tube, and circumferentially equidistantly arranged on the outer peripheral surface of the magnet support tube An eddy current reduction device having a large number of magnets coupled to the guide cylinder and a large number of ferromagnetic plates cast into the guide cylinder, and generating a braking force based on an eddy current on the braking drum by a magnetic field from the magnet; A large number of axial grooves are provided at intervals in the circumferential direction on an inner peripheral surface of the brake drum facing the outer cylindrical portion.

[0005] Further, the structure of the present invention has a brake drum connected to a rotating shaft, and an inner space arranged to face the inside of the brake drum and having a rectangular cross section, and is opposed to the inner peripheral surface of the brake drum. The outer cylinder part is formed of a thin plate of a non-magnetic material, and the inner cylinder part not facing the inner peripheral surface of the braking drum is a guide cylinder made of a ferromagnetic material, and is supported movably in the axial direction by the inner space of the guide cylinder. And an outer peripheral surface having a magnet support cylinder that couples a large number of magnets at equal intervals in the circumferential direction, wherein an eddy current reduction device that generates a braking force based on an eddy current on the braking drum by a magnetic field from the magnet, A large number of axial grooves are provided at intervals in the circumferential direction on an inner peripheral surface of the brake drum facing the outer cylindrical portion.

Further, the structure of the present invention has a braking drum connected to a rotating shaft, and an inner space which is disposed so as to face the inside of the braking drum and has a rectangular cross section, and is opposed to an inner peripheral surface of the braking drum. An outer cylinder portion made of a non-magnetic material and a ferromagnetic plate is cast at equal intervals, and an inner cylinder portion not facing the inner peripheral surface of the braking drum is made of a ferromagnetic material. A magnet support cylinder that is axially movably supported in the hollow portion and couples a large number of magnets on the outer peripheral surface at equal circumferential intervals, and a braking force based on eddy current is applied to the braking drum by a magnetic field from the magnets. In the eddy current reduction device to be generated, a large number of axial grooves are provided on the inner peripheral surface of the braking drum facing the outer cylindrical portion at intervals in the circumferential direction.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, in order to improve the flow of outside air along the inner peripheral surface of the brake drum, a plurality of grooves, preferably inclined with respect to the rotation axis, are formed in the inner peripheral surface of the brake drum. Grooves are provided. As a result, the area of the ventilation path between the inner peripheral surface of the braking drum and the outer cylindrical portion of the guide cylinder is increased, and the traveling wind of the vehicle flows in the axial direction through the gap between the two. Specifically, the traveling wind flows from the distal end side to the proximal end side of the braking drum,
It is discharged outside through the space between the support arms connecting the brake drum and the boss. The reason for inclining the direction of the groove with respect to the rotation axis is to allow the traveling wind to flow in the axial direction without being twisted so much in consideration of the rotation direction of the braking drum. When the groove is inclined with respect to the rotation axis of the brake drum, the groove acts as a fan utilizing the viscosity of air. That is, since the circumferential velocity of the air gradually increases from the inside of the groove to the outside of the groove (the outer surface of the outer cylinder portion of the guide cylinder), the air is positively sucked into the gap.

By providing vanes on the rotating portion of the braking drum, for example, on the outer peripheral surface of the boss portion of the braking drum, the support arm, and the outer peripheral surface of the braking drum of the parking brake connected to the rotating shaft together with the boss portion. With this configuration, the outside air is introduced into the inside of the brake drum from the distal end side by the fan, and flows to the base end of the brake drum along the groove between the brake drum and the outer cylinder portion of the guide cylinder, so that the brake drum is efficiently operated. It is cooled down and discharged to the outside through the space between the support arms.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An eddy current reduction device comprises a braking drum 7 made of a conductor shown in FIG. 1, an immovable guide tube 18 made of a non-magnetic material shown in FIG. 3)
And a stationary magnet support cylinder 59 fixed to the guide cylinder 18 by pins 30. A large number of cooling fins 8 are provided on the outer peripheral surface of the braking drum 7 at equal intervals in the circumferential direction. A plurality of support arms 6 extending radially from the boss 5 are provided at the base end of the braking drum 7.
Are joined by welding or the like. The guide cylinder 18 having an inner space 25 having a rectangular cross section is supported by a non-rotating portion of the vehicle body so as to face the inside of the brake drum 7. As shown in FIGS. 1 and 3, a mounting piece 5a integral with the boss 5 is provided together with the bolt 4 and the nut 4 together with the end wall of the brake drum 3 of the parking brake.
a, it is fitted to the rotating shaft 1 via the spline 1a and is coupled to the mounting flange 2 fastened by the nut 1b. As shown in FIG. 2 and FIG.
A large number of magnets 20, 60 are respectively opposed to the ferromagnetic plates 21 of the outer tube portion 18 a of the guide tube 18, and the polarity of the ferromagnetic plates 21 is set in the circumferential direction in each of the magnet support tubes 19, 59 accommodated in the guide tube 18. Alternately coupled differently.

As shown in FIG. 2, the guide cylinder 18 has an outer cylinder 18a and an inner cylinder 18 made of a non-magnetic material such as aluminum.
At both ends of the cylindrical member b, annular end walls 18c and 18e are integrally joined, and a large number of ferromagnetic plates 21 are joined to the outer cylindrical portion 18a at equal intervals in the circumferential direction. Actually, the ferromagnetic plate 21 is cast when casting the outer cylindrical portion 18a. The guide tube 18 has a flange 31b (FIG. 2) integral with the inner tube portion 18b fixed to a non-rotating portion of the vehicle body such as a wall of a vehicle transmission by bolts. An actuator 26 connected to the end wall 18c of the guide cylinder 18 has a piston 28 inserted into a cylinder 27 to define oil chambers at both ends, and a rod connected to the piston 28 projects outside from the cylinder 27 and a magnet support cylinder. 19 is connected to an arm 17a projecting through a slit 16 of an end wall 18c. The magnet support cylinder 19 is configured to be rotatable forward and backward by the actuator 26 by the arrangement pitch of the magnets 20. In the oil chamber of the actuator 26, the conduit 23,
24 is supplied with pressurized oil, and the other is returned to the oil tank.

As shown in FIGS. 4 and 5, according to the present invention, a number of axial grooves 22 are provided on the inner peripheral surface 7b of the braking drum 7. The direction of the groove 22 is inclined with respect to the rotation axis of the brake drum 7, so that the traveling wind can easily flow in the axial direction along the inner peripheral surface 7 b of the brake drum 7.

As shown in FIG. 3, a fan 35 is preferably formed on the outer peripheral surface of the braking drum 3 by connecting a number of blades 35a at equal intervals in the circumferential direction. In the illustrated embodiment, the blades 35 a are curved in an arcuate cross section, and are connected to be inclined with respect to the axial direction of the brake drum 3. The fan 35 sucks outside air from the left end side of the guide tube 18 into the inside of the guide tube 18,
The air blows rightward through the space between the support arms 6.
The fan 35 may be formed by connecting a large number of blades 35 a to the outer peripheral surface of the boss 5 at equal intervals in the circumferential direction.

Next, the operation of the eddy current reduction device according to the present invention will be described. At the time of non-braking, as shown in FIG. 3, when the polarities of the magnets 20 and 60 facing the ferromagnetic plate 21 are different, a short-circuit magnetic circuit w is formed between the magnet support cylinders 19 and 59 and the ferromagnetic plate 21. It is formed and does not exert a magnetic field on the braking drum 7. At the time of braking, as shown in FIG. 4, the magnet support cylinder 19 is rotated by the pitch of the arrangement of the magnets 20, and when the magnets 20, 60 have the same polarity with respect to the ferromagnetic plate 21, the magnets 2
When a magnetic field of 0,60 reaches the brake drum 7 via the ferromagnetic plate 21 and the rotating brake drum 7 crosses the magnetic field, a braking torque based on an eddy current flowing through the brake drum 7 is generated. At this time, a magnetic circuit z is generated between each of the magnet support cylinders 19 and 59 and the braking drum 7.

The heat based on the eddy current during braking is applied to the braking drum 7.
Not only is heated, but also transmitted to the guide tube 18. The brake drum 7 is cooled by the cooling fin 8 by the outside air, and the running wind of the vehicle flows along the groove 22 of the brake drum 7 from the tip end side of the brake drum 7, and the brake drum 7 and the guide cylinder 18
Is cooled and blown rightward through the space between the support arms 6. Further, the outside air is sucked into the inner cylinder part 18b from the left end side of the guide cylinder 18 by the fan 35, cools the inner cylinder part 18b, and is blown rightward through the space between the support arms 6.

The eddy current reduction device shown in FIG. 6 is provided with a clutch 73 and a gear speed increaser 57 between the rotating shaft and the braking drum 7, and particularly in a low-speed operation, the rotational speed of the braking drum 7 is higher than that of the rotating shaft. Increase to increase the braking effect. A large number of axial grooves 22 are provided on the inner peripheral surface 7b of the braking drum 7. Further, each support arm 6 includes a blade 35a projecting obliquely inward and a blade 35b projecting obliquely outward to form the fan 35. .

A flange 55a of the support cylinder 55 is fastened to the mounting flange 2 fitted and fixed to a rotating shaft (not shown) via a spline 1a by a bolt 4 and a nut 4a.
The cylindrical boss 5 is rotatably supported on the support cylinder 55 by a bearing 56. The base end (right end) of the brake drum 7 having the cooling fin 8 is connected to the base end of the boss 5 via a number of support arms 6 extending in the radial direction. Each support arm 6 is provided with a blade 35a projecting obliquely inward and a blade 35b projecting obliquely outward substantially in parallel with the blade 35a.

An immobile guide cylinder 18 housed inside the brake drum 7 has an outer cylindrical portion 18a facing the inner peripheral surface 7b of the brake drum 7, and an inner cylindrical portion not facing the inner peripheral surface 7b of the brake drum 7. 18b, an annular left end wall (not shown) and a right end wall 1
8e to form an inner space 25 having a rectangular cross section. Outer cylinder 18a made of non-magnetic material such as aluminum
, A large number of ferromagnetic plates 21 are cast at equal intervals in the circumferential direction.

A movable magnet support tube 19 and an immovable magnet support tube 59 are accommodated in an inner space 25 of the guide tube 18, and the magnet support tube 19 is supported by the inner tube portion 18b by the bearing 15.
The magnet support cylinder 59 is fixed to the end wall 18e by the pin 30. A large number of magnets 20 and 60 facing each ferromagnetic plate 21 are coupled to the outer peripheral surface of each magnet support cylinder 19 and 59 at regular intervals in the circumferential direction and alternately have different polarities to the ferromagnetic plate 21 in the circumferential direction. You. A roller 62 is supported on the left end wall of the magnet support cylinder 19 via a support plate 63. Although not shown, the roller 62 is engaged with a groove formed on an end side surface of a rod 61 extending from an actuator formed by inserting a piston into a cylinder. When the rod 61 is reciprocated in a direction substantially perpendicular to the plane of the drawing by the actuator, the magnet support cylinder 19 is rotated forward and backward by the pitch of the magnets 20, and switching between non-braking and braking is performed in the same manner as shown in FIG. Is made. Rod 6
The engaging portion between the roller 1 and the roller 62 is covered by a cover 68.

An annular support frame 71 integral with the inner cylinder portion 18b of the guide cylinder 18 is fitted around the cylindrical wall 42a of the end wall of the gear box 42 of the vehicle transmission, and is shown together with the support cylinder 69. Secured by unbolted bolts. The gear speed increaser 57 has a boss 5
A planetary gear 75 is meshed between a ring gear 5b formed on the left end of the lens and a sun gear 76a formed on an inner cylinder 76 rotatably supported by a bearing 77 on a support cylinder 69. It is rotatably supported by a support shaft 74 fixed to the left end flange of the support cylinder 55. When increasing speed, inner cylinder 76
A plurality of annular friction plates spline-supported on the inner peripheral wall of the outer cylinder 72 integrated with the support frame 71, and a plurality of annular friction plates spline-supported on the outer peripheral wall of the inner cylinder 76. Are alternately overlapped in the axial direction, and the inner cylinder 76 is fixed when both friction plates are pressed by the actuator 64.

The actuator 64 is formed by inserting a piston 67 into a cylinder 65 integrated with a support frame 71, and
When the pressurized fluid is supplied from the cylinder 6 to the end chamber of the cylinder 65, the piston 67 moves to the right, and the friction plate of the outer cylinder 72 and the inner cylinder 7
6, the frictional engagement with the friction plate is achieved, and the braking drum 7 is rotated at a higher speed than the rotating shaft, so that the braking effect is enhanced. Therefore, when the braking drum 7 is rotated together with the boss 5 at a speed higher than the rotation axis, the braking drum 7 is cooled by the cooling fin 8 by the outside air, and the running wind of the vehicle is reduced by the tip of the braking drum 7. It flows along the groove 22 of the brake drum 7 from the side, cools the brake drum 7 and the guide cylinder 18, and is blown rightward through the space between the support arms 6. Further, the outside air is sucked into the inner cylinder portion 18b from the left end side by the fan 35 of the guide cylinder 18, cools the inner cylinder portion 18b, and is blown rightward through the space between the support arms 6.

The eddy current reduction device shown in FIG. 7 switches between a braking position in which the magnet support tube 19 is inserted into the inside of the brake drum 7 and a non-braking position in which the magnet support tube 19 is pulled out of the brake drum 7. It is. The guide cylinder 18 whose right half part projects into the inside of the brake drum 7 has an outer cylinder part 18a facing the inner peripheral surface 7b of the brake drum 7 and is formed of a thin plate made of a non-magnetic material such as stainless steel. The left end portion of the outer tube portion is fitted to the conical surface 18d of the outer tube portion 38, and the right end portion of the outer tube portion 18a is bent inward in a radial direction and overlapped on the end wall 18e. Be combined. The outer cylindrical portion 38, the left end wall 18c, and the inner cylindrical portion 18b made of a magnetic material are configured as a C-shaped cylindrical body, and the right end wall 1 is formed.
8e is preferably formed from a non-magnetic material. Guide tube 18
The magnet support cylinder 19 is accommodated in the inner space 25 so as to be able to reciprocate in the axial direction. A large number of magnets 20 are connected to the outer peripheral surface of the magnet support tube 19 at equal intervals in the circumferential direction and so that the polarity with respect to the outer tube portion 18a is alternately changed in the circumferential direction.

The actuator 26 connected to the left end wall 18c has chambers 29 and 29a defined by inserting a piston 28a into a cylinder 27a, and the inner space 2 is separated from the piston 28a.
The magnet support cylinder 19 is connected to the rod 17 protruding to the side 5.

The inner peripheral surface 7b of the braking drum 7
Similar to those shown in FIGS. 5 and 6, a number of grooves 22 are provided which are inclined with respect to the rotation axis of the braking drum 7. The distal end of the support arm 6 extending radially from the boss 5 connected to the rotating shaft is connected to the base end of the brake drum 7 having the cooling fin 8 by welding. Each support arm 6 is provided with a blade 35a protruding obliquely inward similar to that shown in FIG. 6, and a blade 35b protruding obliquely outward substantially in parallel with the blade 35a.

In the braking state shown in the drawing, the magnetic field from the magnet 20 exerts a magnetic field on the braking drum 7 via the extremely thin outer cylinder portion 18a to generate a braking torque on the braking drum 7. At this time, a magnetic circuit z is generated between the magnet support cylinder 19 and the braking drum 7 as shown in FIG. While the vehicle is traveling, traveling wind enters along the groove 22 of the inner peripheral surface 7b from the left end side of the braking drum 7 to cool the inner peripheral surface 7b of the braking drum 7 and the outer cylindrical portion 18a, and the space between the support arms 6 is formed. After that, it is discharged to the right. By providing the fan 35 on the support arm 6, the traveling wind is more easily introduced into the inner peripheral surface 7b of the braking drum 7, and the cooling performance of the braking drum 7 is enhanced.

When no braking is applied, the chamber 29a of the actuator 26
When the pressurized fluid is supplied to and the pressurized fluid in the chamber 29 is discharged,
Magnet support cylinder 1 via rod 17 by piston 28a
9 is pulled out from the braking drum 7 to the left. At this time, a short-circuit magnetic circuit is generated between the magnet support cylinder 19 and the outer cylinder 38.

In the above-described embodiment, the outer cylindrical portion 18a facing the inner peripheral surface 7b of the braking drum 7 is not formed of a thin plate made of a non-magnetic material such as stainless steel. The same effect can be obtained by using a cylinder made of a non-magnetic material into which a plate is cast.

In each of the above embodiments, the magnets 20 and 60 have a trapezoidal or semicircular cross section rather than a rectangular cross section of the axial groove 22 provided on the inner peripheral surface 7b of the braking drum 7. Magnetic flux reaching the brake drum 7 from the brake drum 7 via the ferromagnetic plate 21 (and the same magnetic flux entering the magnets 20 and 60 from the brake drum 7 via the ferromagnetic plate 21) flows between the grooves 22 on the inner peripheral surface 7b. It comes to concentrate on the protruding part, and the braking force is improved.

[0028]

As described above, in the present invention, since the axial groove is provided on the inner peripheral surface of the braking drum, the gap between the inner peripheral surface of the braking drum and the outer cylindrical portion of the guide cylinder is provided. The area of the ventilation path is enlarged, and the running wind of the vehicle is smoothly introduced into the axial groove of the brake drum, and is discharged to the outside from between the support arms after cooling the inner peripheral surface and the outer cylindrical portion of the brake drum. . In particular, if the groove is inclined with respect to the rotation axis, the traveling wind is more easily introduced into the inside of the brake drum, the cooling performance is enhanced, and the braking drum is cooled on the outer peripheral side by the cooling fins, Since the overheating of the eddy current reduction device due to the heat of the eddy current is suppressed, it is possible to suppress a decrease in the braking ability due to the overheating, particularly during braking during high-speed running of the vehicle.

Since only grooves in the axial direction are formed on the inner peripheral surface of the braking drum of the conventional eddy current reduction device, manufacturing costs can be minimized. Also, if the cross-sectional shape of the groove is trapezoidal or semicircular, the magnetic flux reaching the brake drum from the magnet via the ferromagnetic plate concentrates on the protrusion that partitions between the grooves on the inner peripheral surface of the brake drum. And the braking force is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a braking drum of an eddy current reduction device to which the present invention is applied.

FIG. 2 is a perspective view showing a guide cylinder of the eddy current reduction device.

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

FIG. 4 is a side sectional view of the eddy current reduction device.

FIG. 5 is a developed plan view showing an inner peripheral surface of a braking drum of the eddy current reduction device.

FIG. 6 is a front sectional view of another eddy current reduction device to which the present invention is applied.

FIG. 7 is a front sectional view of another eddy current reduction device to which the present invention is applied.

[Explanation of symbols]

1: rotating shaft 5: boss 5b: ring gear 6: support arm 7: braking drum 7b: inner peripheral surface 8: cooling fin
18: Guide cylinder 18a: Outer cylinder part 18b: Inner cylinder part 19: Magnet support cylinder 20: Magnet 21: Ferromagnetic plate 2
2: Groove 25: Inner space 26: Actuator 35: Fan 57: Gearbox 59: Magnet support cylinder 60: Magnet 64: Actuator 71: Support frame 7
3: clutch 75: planetary gear 76a: sun gear

Claims (4)

[Claims] A guide drum made of a non-magnetic material having a hollow section with a rectangular cross section attached to a non-rotating part of a vehicle body or the like so as to face the inside of the braking drum; At least one movable magnet support cylinder accommodated in the inner space of the guide cylinder, a large number of magnets connected to the outer peripheral surface of the magnet support cylinder at equal intervals in the circumferential direction, and a large number of cast magnets in the guide cylinder. A magnetic plate, and an eddy current reduction device that generates a braking force based on eddy current on the braking drum by a magnetic field from the magnet; in the inner peripheral surface of the braking drum facing the outer cylinder portion, a large number of An eddy current reduction device, wherein axial grooves are provided at intervals in a circumferential direction. 2. A brake drum coupled to a rotating shaft, and an outer cylinder portion having an inner space having a rectangular cross section and being arranged so as to face the inside of the brake drum, and facing an inner peripheral surface of the brake drum. An inner cylinder portion made of a non-magnetic thin plate and not facing the inner peripheral surface of the braking drum is a guide cylinder made of a ferromagnetic material, and is supported movably in the axial direction by an inner space portion of the guide cylinder and has an outer peripheral surface. An eddy current reduction device that has a magnet support cylinder that couples a large number of magnets at equal intervals in the circumferential direction, and that generates a braking force based on an eddy current on the braking drum by a magnetic field from the magnet.
An eddy current reduction device, wherein a number of axial grooves are provided at intervals in a circumferential direction on an inner peripheral surface of the braking drum facing the outer cylindrical portion. 3. A brake drum connected to a rotating shaft, and an outer cylinder portion having an inner space having a rectangular cross section and being disposed so as to face the inside of the brake drum, and facing an inner peripheral surface of the brake drum. Made of non-magnetic material and cast ferromagnetic plates at equal intervals,
A guide tube made of a ferromagnetic material, the inner tube portion not facing the inner peripheral surface of the braking drum; An eddy current reduction device that generates a braking force based on an eddy current on the braking drum by a magnetic field from the magnet, the inner peripheral surface of the braking drum facing the outer cylinder portion. An eddy current reduction device characterized in that a number of axial grooves are provided at intervals in the circumferential direction. 4. The eddy current reduction device according to claim 1, wherein the groove is inclined with respect to the rotation axis of the braking drum.