JP2001327154A - Eddy current reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the braking force by thinning the outer casing of a guide case including a ferromagnetic plate as far as possible, and arranging a magnet supporting case in radially outward direction. SOLUTION: A guide case 21 consisting of nonmagnetic substance being attached to the nonrotation section of a car body or the like and having an inner space part oblong in cross section is arranged inside a braking drum 8 coupled with a rotary shaft. At least one magnet supporting case 25 is supported rotatably inside the inner space part of the guide case 21. Many magnets 15 are coupled with one another at equal intervals in peripheral direction at the outside periphery of the magnet supporting case 25. The braking force is generated in the braking drum 8 by the eddy currents based on the magnetic fields from the magnets 15. The magnets 15 are arranged so that the ends in peripheral direction may form magnetic poles, and a ferromagnetic member 16 projecting outward in diametrical direction rather than the magnet 15 is put between the magnet 15 and the magnet 15. The outer casing 41 of the guide case 21 is made into a nonmagnetic or weakly magnetic austenite phase by quenching the section not opposed to the ferromagnetic member 16 of a thin stainless steel plate being ferromagnetic substance from high temperature condition.

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 in which a braking force is increased by reducing a radial dimension of an outer cylinder portion of a guide cylinder and supporting a magnet support cylinder in a radially outward direction. .

[0002]

2. Description of the Related Art In an eddy current reduction device disclosed in, for example, U.S. Pat. No. 5,143,183, a large number of ferromagnetic plates (pole pieces) arranged at equal circumferential intervals on an outer cylinder portion of a guide cylinder are provided. Because it is very thick, the magnetic field reaching the brake drum from a magnet (permanent magnet, the same applies hereinafter) is weakened, and casting a ferromagnetic plate into the outer cylinder of a guide cylinder made of aluminum casting causes cracks. The yield is poor, and it takes time to machine the peripheral surface after casting. In the case where the outer cylindrical portion of the guide cylinder is formed of a thick stainless steel plate made of magnetic material such as ferrite or martensite and is subjected to heat treatment to form a non-magnetic portion, the heat treatment cost is increased because the stainless steel plate is thick. Further, if the ferromagnetic plate is thick, it is impossible to magnetize the magnet portion from the outside of the ferromagnetic plate after accommodating the magnet support tube in the inner space of the guide tube before magnetizing the magnet. Magnetizing the magnet of the magnet support cylinder and assembling it into the inner space of the guide cylinder means that the magnet of the magnet support cylinder exerts a strong attractive force on the guide cylinder, and the magnet support cylinder is moved to a predetermined position in the inner space of the guide cylinder. It takes time to support.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to reduce the thickness of the outer cylinder of a guide cylinder including a ferromagnetic plate as much as possible and to dispose the magnet support cylinder radially outward. It is an object of the present invention to provide an eddy current reduction device with enhanced power.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a brake drum connected to a rotating shaft and a rectangular cross-section inside the brake drum and attached to a non-rotating portion such as a vehicle body. A guide tube made of a non-magnetic material having an inner space portion, at least one magnet support tube rotatably supported by the inner space portion of the guide tube, and circumferentially equally spaced circumferential surfaces of the magnet support tube A plurality of magnets coupled to the eddy current reduction device that generates a braking force on the braking drum by eddy current based on a magnetic field from the magnet, wherein the magnets are arranged such that circumferential ends form magnetic poles. Then, a ferromagnetic member projecting radially outward from the magnet is sandwiched between the magnets,
The outer cylinder part of the guide cylinder is made of a thin stainless steel sheet that is a ferromagnetic material, and the part of the stainless steel sheet that does not face the ferromagnetic member is rapidly cooled from a high temperature state to a nonmagnetic or weakly magnetic austenitic phase. I do.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the outer cylinder portion of a guide cylinder is made of a thin stainless steel plate which is a ferromagnetic material, and the portion of the stainless steel plate facing the magnet is rapidly cooled from a high temperature state to an austenitic phase when not braking. , Forming a non-magnetic or weak magnetic portion. On the other hand, a large number of magnets are connected to the outer peripheral surface of a magnet support cylinder made of a nonmagnetic material at equal intervals in the circumferential direction so that the circumferential ends of the magnets form magnetic poles. With the member (or the electromagnetic steel plate) interposed, the magnet, the ferromagnetic member, and the magnet support tube are formed as a rigid cylindrical body having a predetermined thickness. By reducing the thickness of the outer cylinder of the guide cylinder, the magnet support cylinder is brought closer to the inner peripheral surface of the braking drum, and the braking force is increased. Further, after the magnet support cylinder before magnetization is accommodated and supported in the inner space of the guide cylinder, the magnet of the magnet support cylinder can be magnetized from outside the outer cylinder part.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 and 2, an eddy current reduction device according to the present invention has a boss portion 5 of a braking drum 8 attached to a mounting flange 3 which is spline-fitted to, for example, an output rotary shaft 2 of a vehicle transmission. The flange 5a and the end wall of the brake drum 4 of the parking brake are fastened together by a plurality of bolts 6 and nuts. A base end or a right end of a brake drum 8 provided with a large number of cooling fins 9 on its outer peripheral surface is joined to a distal end of a large number of support arms 7 projecting radially outward from the boss portion 5 by welding or the like.

[0007] At both ends of the inner peripheral surface of the braking drum 8 that do not face the ferromagnetic portion (pole piece) 41a and at the end wall surface of the braking drum 8, an annular body 51 made of a good conductor such as copper is provided.
52 are combined. Each of the annular plates 51 and 52 is
In this case, the eddy current generated in the motor is extended in the axial direction to increase the braking torque.

A guide cylinder 21 having an inner space with a rectangular cross section is disposed inside the braking drum 8, and the guide cylinder 21 has both end walls 24 made of a non-magnetic material such as aluminum and an inner cylinder made of a non-magnetic material. An inner space having a rectangular cross section is formed by the portion 22 and the outer cylindrical portion 41 made of a thin stainless steel plate. A ferromagnetic portion 41a and a nonmagnetic or weak magnetic portion 41b are formed in the outer cylinder portion 41 at equal intervals in the circumferential direction and alternately in the circumferential direction by partial heat treatment. Specifically, the ferromagnetic portion 41a of the outer cylindrical portion 41 made of a martensitic or ferritic stainless steel plate is left as it is, and only the non-magnetic or weakly magnetic portion 41b is locally heated to a high temperature (8
(From 0 to 1350 ° C.) and rapidly cooled to a nonmagnetic or weakly magnetic austenitic phase.

A movable magnet support tube 25 made of a non-magnetic material and an immovable magnet support tube 65 are arranged in the inner space of the guide tube 21 in the axial direction, and a thrust washer 18 made of a bearing metal is interposed therebetween. Is interposed. The movable magnet support tube 25 is supported by the inner cylinder portion 22 by the bearing 10 so as to be capable of rotating forward and backward, and the magnet support tube 65 is fixed to the inner cylinder portion 22 by the pin 19.

[0010] As shown in FIG.
Numeral 5 is coupled to the outer peripheral surface of the magnet support cylinder 65 such that the circumferential end surface becomes a magnetic pole. A block-like ferromagnetic member 56 is sandwiched between the magnets 55 adjacent in the circumferential direction, and is connected to the outer peripheral surface of the magnet support cylinder 65 by radial bolts (not shown). The ferromagnetic member 56 is projected radially outward from the magnet 55, and a retaining projection 56 a projecting from the circumferential end face on the outer end side is engaged with the outer end face of the magnet 55 so that the magnet 55 does not fall off. . Thus, the magnet support cylinder 65, the magnet 55, and the ferromagnetic member 56 have a predetermined axial dimension, and are integrally formed as a cylinder in which the outer peripheral surface of the ferromagnetic member 56 forms an arc surface. Similarly, the magnet 15 and the ferromagnetic member 16
Is combined with In the embodiment shown in FIGS. 1 and 2, the circumferential dimension of the ferromagnetic members 16 and 56 is longer than the magnets 15 and 55, but as shown in FIGS.
The circumferential dimension of 56 may be equal to that of magnets 15,55.

As shown in FIG. 1, a movable magnet support cylinder 25
A fluid pressure actuator 31 for forward and reverse rotation of a piston is inserted into a cylinder 32 formed integrally with the end wall 24 to divide the both end chambers, and the outer end of a rod connected to the piston 33 is supported by a magnet. Slit 3 from tube 25 to end wall 24
5 and connected to an arm 34 protruding to the outside.

In the eddy current reduction device described above, when the brake is not applied, the polarities of the magnets 15 of the magnet support cylinder 25 and the magnets 55 of the magnet support cylinder 65 arranged in the axial direction with respect to the ferromagnetic portion 41a of the outer cylinder 41 are mutually opposite. In the opposite state, a short-circuit magnetic circuit w is generated between the ferromagnetic portion 41a and the magnets 15 and 55 as shown in FIGS. Since the magnetic fields of the magnets 15 and 55 do not reach the braking drum 8, no braking torque is generated on the braking drum 8. At the time of braking, when the magnet support cylinder 25 is rotated by the arrangement pitch of the magnets 15 by the fluid pressure actuator 31, as shown in FIG.
The polarities of the magnets 15 and 55 of the magnet support cylinders 25 and 65 become the same. Therefore, the rotating braking drum 8 is
When crossing the magnetic field from 5, 55, a braking torque is generated in the braking drum 8 based on the eddy current. At this time, as shown in FIG. 2, a magnetic circuit z is generated between the braking drum 8 and the magnet support cylinders 25 and 65.

In the embodiment shown in FIG.
Magnets 15 and 55 coupled to outer peripheral surfaces of 5, 65 and magnet 1
The ferromagnetic members 16 and 56 are sandwiched between the ferromagnetic members 5 and 55, respectively, and a groove 39 is formed in the outer surface of each of the ferromagnetic members 16 and 56 to form a groove-type (channel-type) side section. Each magnet 15,
55 has a magnetic pole at the circumferential end face, and only outer end faces of the ferromagnetic members 16, 56 sandwiching the circumferential end faces of the magnets 15, 55 project radially outward from the magnets 15, 55. The outer cylindrical portion 41 of the guide cylinder 21 is partially heat-treated so that the magnetic portion 41 facing the outer surface of the end of each of the ferromagnetic members 16 and 56 during braking is provided.
a and a nonmagnetic or weak magnetic portion 41b which does not face the outer surface of the end of each of the ferromagnetic members 16, 56 is formed. Specifically, the ferromagnetic portion 41a of the outer cylindrical portion 41 made of a martensitic or ferritic stainless steel plate is left as it is, and only the nonmagnetic or weakly magnetic portion 41b is locally heated to a high temperature (800 ° C). (1350 ° C.) and rapidly cooled to a nonmagnetic or weakly magnetic austenitic phase.
Other configurations are the same as those shown in FIGS. 1 and 2, and have similar functions and effects.

[0014]

As described above, the present invention provides a brake drum connected to a rotating shaft, and a non-magnetic material having a rectangular cross-section inside the brake drum and attached to a non-rotating portion such as a vehicle body. A guide cylinder comprising at least one magnet support cylinder rotatably supported in the inner space of the guide cylinder, and a number of magnets connected to the outer peripheral surface of the magnet support cylinder at equal intervals in the circumferential direction. And in an eddy current reduction device that generates a braking force on the braking drum by eddy current based on a magnetic field from the magnet, the magnet is disposed such that a circumferential end forms a magnetic pole,
A ferromagnetic member projecting radially outward from the magnet is sandwiched between the magnets and the magnet, and the outer cylinder portion of the guide cylinder is formed of a thin stainless steel plate that is a ferromagnetic material. The non-opposed parts are rapidly cooled from a high temperature state to a non-magnetic or weak magnetic austenitic phase, so the outer cylinder part of the guide cylinder is thin, and the braking force is increased by arranging the magnet support cylinder radially outward. Can be.

Processing of the guide tube is simplified, the yield is better, the processing cost can be reduced, and the weight can be reduced as compared with a conventional example in which a ferromagnetic plate is cast into an outer tube made of aluminum or the like.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention when braking is not performed.

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

FIG. 3 is a plan sectional view showing a magnet support cylinder in a non-braking state of a eddy current reduction device according to a partially modified embodiment of the present invention, which is developed in a circumferential direction.

FIG. 4 is a side sectional view showing a magnet support cylinder of the eddy current reduction device developed in a circumferential direction.

FIG. 5 is a side sectional view of an eddy current reduction device according to a partially modified embodiment of the present invention during braking.

[Explanation of symbols]

2: Rotary shaft 5: Boss 7: Support arm 8: Brake drum 15, 55: Magnet 16, 56: Ferromagnetic member 21:
Guide tube 22: Inner tube portion 24: End wall 25, 65: Magnet support tube 31: Actuator 41 Outer tube portion 41a:
Ferromagnetic part 41b: Non-magnetic or weak magnetic part

Claims (2)

[Claims] 1. A guide cylinder made of a non-magnetic material having a rectangular cross section and being mounted on a non-rotating part such as a vehicle body inside the brake drum and connected to a rotating shaft, At least one pivotally supported in the inner space of the cylinder
An eddy current for generating a braking force on the braking drum by an eddy current based on a magnetic field from the magnet, comprising: a plurality of magnet support cylinders; and a number of magnets coupled to an outer peripheral surface of the magnet support cylinder at equal circumferential intervals. In the reduction gear transmission, the magnet is disposed so that its circumferential end forms a magnetic pole, a ferromagnetic member projecting radially outward from the magnet is sandwiched between the magnet and the magnet, and an outer cylindrical portion of the guide cylinder is provided. An eddy current reduction device characterized by comprising a thin stainless steel plate which is a ferromagnetic material, and rapidly cooling a portion of the stainless steel plate not facing the ferromagnetic member from a high temperature state to a non-magnetic or weakly magnetic austenitic phase. 2. The outer cylindrical portion of the guide tube is made of a thin stainless steel plate of martensite or ferrite, and the ferromagnetic portion of the outer tube portion is left as it is, and only the non-magnetic or weakly magnetic portion is heated. Rapidly cooled from 800 to 1350 ° C. to a non-magnetic or weakly magnetic austenitic phase,
The eddy current reduction device according to claim 1.