JP2701084B2 - Eddy current type reduction gear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an eddy current type speed reducer using a permanent magnet as a magnetic force source, and in particular, to an eddy current type speed reducer that reduces drag braking when control is released. About.

[Related Art] In general, a deceleration braking device that applies stable and continuous deceleration braking to a vehicle so as to prevent acceleration occurring on the vehicle when a vehicle descends on a long hill or the like, thereby preventing burnout of a foot brake that is a main brake. An eddy current type reduction gear is known as a (retarder).

This eddy current type speed reducer is composed of a rotor attached to a rotating shaft such as a propeller shaft linked to the rotation of wheels, and a magnetic force such as an electromagnet or a permanent magnet attached to a fixed side of a body frame or the like in close proximity to the rotor. The rotor generates a eddy current for braking the rotation of the rotor by a relative speed difference between the fixed-side magnetic force source and the rotor on the rotating side, thereby applying deceleration braking to the vehicle.

In order to reduce the size and weight of such an eddy current type reduction gear, it is advisable to employ a compact permanent magnet having a strong magnetic force for the magnetic force source.

The applicant has previously developed various eddy current type reduction gears using a permanent magnet as a magnetic force source. (For example, Japanese Patent Application No. 1-2184
99, Japanese Patent Application No. 1-2188498, Japanese Patent Application No. 1-2221555, etc.)
FIG. 8 shows an eddy current type reduction gear X as an example.

As shown, the output shaft a at the rear of the transmission
A permanent magnet c positioned inside the rotor b and supported by a transmission case (not shown) is reciprocally movable in the axial direction of the drum-shaped rotor b. In other words, it is provided so as to be movable close to and away from the rotor b.

The permanent magnet c is provided on the support ring d at a predetermined interval so that the magnetic poles facing the inner peripheral surface of the drum-shaped rotor b are alternately N-poles and S-poles.

When the eddy current type reduction gear x is operated to apply deceleration braking to the vehicle, the support ring d around which the permanent magnet c is provided is moved by an actuator e such as an air cylinder as shown by a solid line in FIG. The permanent magnet c on the support ring d is moved closer to the rotor b by sliding to the right. Then, a magnetic circuit connecting the N pole and the S pole is formed between adjacent permanent magnets c having different polarities on the support ring d on the fixed side and the rotor b on the rotation side, and the inner circumference of the rotor b is formed. An eddy current that applies a braking force to the rotation of the rotor b flows through the surface, and a braking force is applied to the output shaft a to which the rotor b is connected, so that the vehicle is decelerated.

To release the deceleration braking, the support ring d around which the permanent magnet c is provided is slid by the actuator e to the left as shown by the broken line in FIG. Is separated from the rotor b, and the permanent magnet c and the rotor b are magnetically disconnected to release the deceleration braking.

[Problems to be Solved by the Invention] By the way, the eddy current flowing through the inner peripheral surface of the rotor b during the deceleration braking causes energy loss and causes the rotor b to generate heat.

Therefore, in order to improve the heat radiation cooling property of the rotor b, the drum width of the rotor b is widened within a limited mounting space for a vehicle with a limited drum width.

However, as shown in FIG. 8, if the drum width w of the rotor b is increased in the direction in which the permanent magnet c is separated (to the left in the drawing), the permanent magnet c at the separated position (indicated by a broken line in the drawing) is released when deceleration braking is released. A part of the magnetism is magnetically connected to the rotor b as shown by one point shift g in the figure through a cover member f made of aluminum (represented by a dot in the figure).

As a result, even when the deceleration braking is released, a small amount of eddy current always flows through the rotor b, and drag braking is applied. The eddy current due to this magnetic leakage is always small,
Therefore, the heat generation amount may be accumulated in the rotor b and cause thermal distortion or thermal cracking in the rotor b.

Further, there is also a problem that dust h such as iron powder adheres to the magnetic leakage portion.

As a countermeasure, the thickness of the cover member f which is provided to cover the permanent magnets b, and formed thicker the thick t ₁ shown in FIG. 8 to the thickness t ₂ as shown in FIG. 9, releasing the brake by increasing the distance l ₁ between the permanent magnet c and the rotor b spaced position when, it is conceivable to reduce the magnetic connection braking drag by the magnetic leakage weakens the permanent magnet c and the rotor b.

However, in this countermeasure, since become distance l ₂ also prolonged the permanent magnet c and the rotor b of the proximity position when braking, which leads also decrease the braking force.

Also, forming the cover member f thicker increases the weight and the outer diameter of the rotor b. Therefore, when the heavy and large eddy current type reduction gear Y is to be mounted on a vehicle, there is a problem that the eddy current type reduction gear Y cannot fit within a limited mounting space and interferes with other parts.

On the other hand, when the drum value of the rotor b shown in FIG. 8 is widened to the right in the figure, contrary to the above, the expanded rotor b is fastened to the output shaft a of the transmission by a propeller shaft (not shown). As a result, a large overhang occurs on the part side, and the workability of fastening the propeller shaft is extremely deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention, which has been made in view of the above circumstances, to provide an eddy current type reduction gear capable of reducing drag braking when releasing deceleration braking without reducing braking force during deceleration braking.

Means for Solving the Problems In order to achieve the above object, an eddy current type speed reducer according to the present invention passes through a cylindrical rotor made of a magnetic material fixed to a rotating shaft and an axis of the rotating shaft. A hollow cover member in which a ferromagnetic material is disposed in parallel with the rotor in a non-magnetic material, and is fixed to a portion facing the rotor in a cross section in a manner facing the inside of the rotor with a small gap; A support ring in which permanent magnets are alternately arranged in the direction, and the support ring is attached to the shaft from a braking position in which the permanent magnet faces the ferromagnetic material in the cover member to a release position of a portion opposite thereto. The permanent magnet and the opposing surfaces of the ferromagnetic material are opposed to each other with a slight gap at a braking position, and separated from the rotor at a release position. Eternity A cutout or inclined surface is formed on the outer surface of the negative magnet, and a protruding portion or inclined surface is formed on the inner surface of the ferromagnetic material opposed to the notch.

[Operation] At the time of deceleration braking release in which the permanent magnet is moved to the release position separated from the rotor, the gap between the permanent magnet and the rotor is widened by the notch or the inclined portion formed on the surface of the permanent magnet facing the rotor. Thereby, an air layer, which is a magnetic insulating material, is formed between the rotor and the permanent magnet to a thickness corresponding to the gap. Therefore, coupled with the fact that the distance between the permanent magnet and the rotor is long, the magnetic connection between the permanent magnet and the rotor is weakened, and drag braking is reduced.

Further, at the time of deceleration braking in which the permanent magnet is brought close to the rotor, by bringing the permanent magnet sufficiently close to the rotor, the reduction of the braking force due to the notch hardly occurs.

Embodiment An embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, a flange portion 2 is formed on an output shaft 1 of a transmission of an automobile so as to extend radially outward of the shaft 1, and a brake drum 3 for a parking brake is formed on the flange portion 2. And the rotor 4 of the eddy current type reduction gear are fastened together by mounting bolts 5.

The rotor 4 is formed of a conductor and a magnetic material, for example, a low-carbon steel material, and is formed in a so-called drum shape with a bottomed cylindrical shape, and is provided coaxially with the output shaft 1. A permanent magnet 7 supported by a transmission case 6 is located inside the drum-shaped rotor 4.
Are reciprocally movable in the axial direction of the drum. Cooling fins 8 are provided outside the drum.

The permanent magnet 7 is provided on an annular support ring 9 which is arranged concentrically with the output shaft 1 and has a support bracket.
The transmission case 10 supports the transmission case 6. More specifically, the permanent magnet 7 is formed from a rare earth element such as neodymium to be lightweight and compact in order to exert a strong magnetic force. As shown in FIG. 3 and FIG. An even number (about 8 to 12) of support rings 9 are circumferentially provided at predetermined intervals so that N poles and S poles are alternately arranged in the circumferential direction facing the surface.

The permanent magnet 7 and the support ring 9 are sealed by a cover member 11 that allows the permanent magnet 7 to move toward and away from the rotor 4.

The cover member 11 is formed in a hollow annular shape concentric with the output shaft 1, and is located on the inner peripheral side of the drum-shaped rotor 4 to have a predetermined gap (air gap) with the rotor 4.
Is provided. The cover member 11 is provided with an actuator 12 composed of an air cylinder for reciprocating the permanent magnet 7.

The cover member 11 that hermetically accommodates the permanent magnet 7 and the support ring 9 is made of a ferromagnetic material 13 (shown by oblique lines in the drawing) having a high magnetic permeability and a magnetic material having a low magnetic permeability depending on the position of the cover member 11. It is formed of a nonmagnetic material 14 (represented by a dot in the figure) which is an insulating material.

More specifically, when the permanent magnet 7 and the support ring 9 are moved rightward (braking position) in the figure as shown by the solid line in FIG. 2 and 3, each permanent magnet 7 on the support ring 9 is connected to the rotor 4
(Pole piece portion) is formed of a ferromagnetic material 13 such as low-carbon steel, and the other portion is formed of a nonmagnetic material 14 such as aluminum. That is, the ferromagnetic material 13 and the non-magnetic material 14 are provided alternately along the circumferential surface of the rotor 4.

When the permanent magnet 7 and the support ring 9 are moved to the left (release position) in the drawing as shown by a broken line in FIG. 1, the cover member 11 transfers the magnetism of the permanent magnet 7 to the cover member.
As shown in FIGS. 2 and 4, a portion surrounding the permanent magnet 7 is formed of a ferromagnetic material 15 such as low carbon steel over the entire circumference in order to shield the inside of the magnet 11 from magnetic fields. I have.

The feature of this embodiment is that, as shown by a broken line in FIG. 1, when the permanent magnet 7 accommodated in the cover member 11 is moved leftward in FIG. upon moving, is that part of the permanent magnet 7 facing the rotor 4 so as to wider gap c ₁ between the permanent magnet 7 and the rotor 4 are cut. Specifically, in the permanent magnet 7, a portion facing the non-magnetic member 14 (indicated by a dot in the drawing) of the cover member 11 is cut out in a concave step shape at a separated position indicated by a broken line in the drawing. That is, the permanent magnet 7 is formed with a concave notch 16.

In response to the notch, when the permanent magnet 7 is moved rightward in the figure, that is, when the permanent magnet 7 is moved close to the rotor 4, the cover member 11 is aligned with the concave notch 16 of the permanent magnet 7. Are partially protruded in a convex shape. That is, a convex protrusion 17 is formed on the inner surface of the cover member 11.

 The operation of the present embodiment having the above configuration will be described.

When decelerating braking is applied to the vehicle, the permanent magnet 7 is moved by the actuator 12 to the right in the drawing, that is, to a braking position facing the inner peripheral surface of the rotor 4, as shown by the solid line in FIG.

Then, as shown in FIG. 3, a magnetic circuit 18 connecting the N pole and the S pole is formed between the permanent magnet 7 on the fixed side and the rotor 4 on the rotating side. An eddy current flows to give braking to the rotation of the rotor 4, and a braking force is applied to the output shaft 1 to which the rotor 4 is fastened, whereby deceleration braking of the vehicle is achieved.

At this time, as shown in FIG.
By 16 and the cover member 11 the inner surface of the convex protrusion 17 is consistent, to reduce the thickness of the air layer c ₂ as a magnetic insulating material which is formed between the permanent magnet 7 and the cover member 11 the inner surface be able to. Therefore, a decrease in braking caused by an increase in the gap (distance) between the concave notch 16 of the permanent magnet 7 and the rotor 4 can be reduced to a minimum.

On the other hand, when releasing the deceleration braking, the permanent magnet 7 is moved by the actuator 12 to the left in the drawing, that is, to the release position separated from the rotor 4, as shown by the broken line in FIG.

Then, as shown in FIG. 4, a magnetic circuit 19 connecting the N pole and the S pole is formed between the permanent magnet 7 on the fixed side and the cover member 11 on the fixed side similarly to the permanent magnet 7 on the fixed side. Thus, no magnetism leaks to the rotor 4 on the rotating side shown in FIG. Therefore, no eddy current is generated in the rotor 4, and the deceleration braking of the vehicle is released.

At this time, as shown in FIG. 1, the permanent magnet 7 is formed with a concave notch portion 16 in which a part thereof is cut in a concave step shape, so that the permanent magnet 7 is located between the permanent magnet 7 and the rotor 4. so that the large gap c ₁ is formed. As a result, the permanent magnet 7
A cover member 11 air layer c ₃ is a small magnetic insulating material of magnetic permeability between the inner surface are formed, I can coupled with the distance becomes farther the permanent magnet 7 and the rotor 4, a permanent magnet The magnetic connection with the rotor is weakened. That is, the concave notch 16 is
Closer is better ferromagnetic body 15 of the cover member 11 than the gap c ₁ rotor 4 separated, the magnetic flux from the notch 16 becomes a magnetic path that passes through the ferromagnetic body 15, as shown in FIG. 4, the rotor 4 does not work.

Therefore, a part of the magnetism of the permanent magnet 7 at the separated position (release position) indicated by the broken line in FIG.
(Aluminum or the like) and drag braking caused by magnetic connection with the rotor 4 is suppressed or reduced to a practically acceptable level.

Therefore, according to the eddy current type reduction gear transmission shown in this embodiment,
As in the case of the eddy current type speed reducer Y shown in FIG. 9, the drag braking at the time of releasing the deceleration braking can be suppressed or reduced to a practically acceptable level without increasing the weight or increasing the size, and the braking force at the time of the deceleration braking. Can be secured sufficiently.

In this embodiment, the concave notch 16 of the permanent magnet 7 is formed in a step shape as shown in FIG. 1. However, the present invention is not limited to this, and the concave notch 16 may be formed in FIG. 5, FIG. As shown in FIG. 7, it may be formed in an inclined shape. In short, the notch increases the gap c ₁ (distance) between the permanent magnet 7 and the rotor 4 at the separated position of the permanent magnet 7, and forms an air layer c _3, which is a magnetic insulating material, in the gap c _1. Any configuration may be used as long as the magnetic connection between the permanent magnet 7 and the rotor 4 is weakened.

[Effects of the Invention] As described above, according to the present invention, the following excellent effects can be exerted.

It is possible to reduce drag braking that occurs when deceleration braking is released, without reducing the braking force during deceleration braking.

[Brief description of the drawings]

FIG. 1 is a sectional side view of an essential part of an eddy current type speed reducer showing one embodiment of the present invention, FIG. 2 is a perspective view of a cover member shown in FIG. 1, and FIG. 3 is III-III in FIG. FIG. 4 is a sectional view taken along a line of FIG.
FIG. 5, FIG. 6, FIG. 7, and FIG. 7 are side sectional views of a main part of an eddy current type speed reducer showing a modified embodiment of the present invention, and FIG. FIG. 2 is a side sectional view showing a main part of an eddy current type speed reducer developed earlier by the applicant. In the figure, 1 is the output shaft is rotating shaft, 4 rotor, 7 permanent magnet, 16 is notch, c ₁ is the clearance.

Claims (1)

(57) [Claims] 1. A cylindrical rotor made of a magnetic material fixed to a rotating shaft, and fixed to the inside of the rotor with a slight gap therebetween in a cross section passing through the axis of the rotating shaft, and fixed to the rotor. In the part to be formed, a hollow cover member in which a ferromagnetic material is arranged in parallel with the rotor in a non-magnetic material, a support ring in which permanent magnets are alternately arranged in the circumferential direction with a polarity, and the support ring An actuator in which the permanent magnet is movable in parallel with the axis from a braking position facing the ferromagnetic material to a release position on the opposite side in the cover member, wherein the permanent magnet and the ferromagnetic material Each facing surface of
A notch or an inclined surface is formed on the outer surface of the permanent magnet so as to face the rotor with a small gap at the braking position and separate from the rotor at the release position, and a protruding portion is formed on the inner surface of the ferromagnetic material opposed to the permanent magnet. Alternatively, an eddy current type reduction gear characterized by forming an inclined surface.