JPH0488864A - Eddy current type reduction gear - Google Patents

Abstract

PURPOSE:To get a eddy current type reduction gear which removes the leaked magnetic flux at nonbraking efficiently by arranging a fixed frame, which has a hollow part, between a pair of braking discs, and supporting outer and inner magnet supporting rings in a pair capably in relative rotation inside the fixed frame, and arranging a permanent magnet at each magnet supporting ring. CONSTITUTION:While braking discs 3 are rotated together with a rotary shaft 2, at braking, in the layout where the polarities to the ferromagnetic plates 6 of the inner and outer permanent magnets 12 and 13 are different, a shorted magnetic close circuit occurs between the ferromagnetic plates 6, and it does not exert the magnetic field upon the braking discs 3. Since the ferromagnetic plates 6 are in the condition of catching the permanent magnets 12 and 13 extensively from both sides, the leaked magnetic flux to the braking discs hardly occur. At braking, when the outer magnet supporting ring 10 is rotated by the pitch of layout by a motor, the polarities to the ferromagnetic plates 6 of the permanent magnets 12 and 13 become the same, and permanent magnets 12 and 13 exert the magnetic fields equally on the braking discs 3 through the ferromagnetic plates 6. When the rotating braking discs 3 cross the magnetic field, an eddy current occurs, and it receives braking torque.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to an eddy current type speed reduction device that assists the friction brake of large vehicles, and in particular, to effectively avoid dragging of a brake disc due to magnetic leakage when not braking. This invention relates to an eddy current speed reduction device.

[Prior Art] In an eddy current reduction gear disclosed in Japanese Patent Application Laid-Open No. 1-298947, a brake disc is connected to a rotating shaft.
A magnet support in which a pair of magnetic control plates are rotatably arranged, and a large number of permanent magnets are connected between the pair of magnetic control plates at equal intervals in the circumferential direction and with alternating polarity with respect to the brake disk. The board is fixed. The pair of magnetic control plates includes non-magnetic plates made of aluminum or the like and ferromagnetic plates having approximately the same area as the permanent magnets, arranged at equal intervals in the circumferential direction.

When braking, the magnetic II is placed at the position where the ferromagnetic plate faces the permanent magnet.
When the IIIl plate is held, the magnetic flux from the permanent magnet passes through the ferromagnetic plate and acts perpendicularly on the brake disc, and when the brake disc crosses the magnetic field, an eddy current is generated in the brake disc, causing the brake disc to Receives braking torque.

When the magnetic control plate is held in a rotational position where the ferromagnetic plate is shifted by the arrangement pitch of the permanent magnets when not braking, two permanent magnets adjacent to each other in the circumferential direction are spaced between a pair of ferromagnetic plates when viewed from the outer circumferential side. Partially sandwiched between two adjacent permanent magnets and the left and right one
A short magnetic closed circuit is formed between the pair of ferromagnetic plates, the magnetic field acting on the brake disc becomes very weak, and the braking torque experienced by the brake disc becomes very small.

However, since the magnetic flux leaking from the central portion of the permanent magnet in the same direction that is not sandwiched between the pair of ferromagnetic plates acts on the brake disk, there is a problem that the brake disk is subjected to drag torque. In order to reduce leakage magnetic flux from the permanent magnets to the braking disk, making the magnetic control plate thicker increases the weight of the entire device and increases the distance between the permanent magnets and the braking disk. The magnetic flux that passes through and reaches the brake disc decreases,
Braking torque decreases.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to provide an eddy current speed reduction device that efficiently eliminates leakage magnetic flux during non-braking without increasing weight. It is in.

[Means for Solving Problem M] In order to achieve the above object, the configuration of the present invention has an inner space made of a non-magnetic material and having a rectangular cross section between a pair of brake discs coupled to a rotating shaft. A cylindrical fixed frame is installed, and a large number of ferromagnetic plates are connected to both side walls of the fixed frame at equal intervals in the circumferential direction.
Inside the fixed frame, a pair of inner and outer magnet support wheels is supported so as to be relatively rotatable, and permanent magnets facing each ferromagnetic plate are arranged in each magnet support ring so that the polarity with respect to the ferromagnetic plate is alternately different. It is something.

[Function] A cylindrical fixed frame having an inner space with a rectangular cross section is arranged between a pair of brake discs, and a large number of ferromagnetic plates facing the brake discs are arranged on both sides of the fixed frame in the circumferential direction. arranged at intervals. A pair of inner and outer magnet support rings are supported in the inner space of the fixed frame so as to be relatively rotatable by the arrangement pitch of the permanent magnets.

When not braking, each permanent magnet of the magnet support ring is sandwiched between a pair of ferromagnetic plates of a fixed frame made of a non-magnetic material, and the permanent magnets of the outer magnet support ring and the permanent magnets of the inner magnet support ring are The polarity is in the opposite position. A short-circuit magnetic closed circuit is formed between the pair of inner and outer permanent magnets and the pair of left and right ferromagnetic plates, and no magnetic field is applied to the brake disk. Since the entire surface of the pair of inner and outer permanent magnets is sandwiched between the pair of left and right ferromagnetic plates, there is almost no leakage magnetic flux.

During braking, when one magnet support ring is rotated by the arrangement pitch of the permanent magnets, the polarity of the pair of inner and outer permanent magnets with respect to the ferromagnetic plate becomes the same, and the magnetic flux from each permanent magnet passes through the ferromagnetic plate. act perpendicularly to the brake disc. rotating l111
11 When the disc crosses the magnetic field, eddy currents are generated in the brake disc, and the brake disc receives a braking torque.

[Embodiments of the Invention] FIG. 1 is a front sectional view of an mmi type reduction gear according to the present invention;
FIG. 2 is a side view of the same. The eddy current speed reduction device according to the present invention includes a braking disc 3 made up of a pair of conductors coupled to an output rotating shaft 2 of a vehicle transmission, and a non-magnetic material disposed at the - of the braking disc 3. A fixed frame 5 consisting of a fixed frame 5, and a pair of inner and outer magnetic support wheels 8.1 supported inside the fixed frame 5 so as to be able to work relative to each other.
It is equipped with 0. The brake disc 3 is spline-fitted and fixed to the boss 3at and the rotating shaft 2. boss 3a and boss 3a
The spokes 3b extending radially from the spokes 3b and the brake disc 3 having the ventilation passage 3C are integrally formed, for example, by casting.

The fixed frame 5 has a cylindrical shape with an inner cavity having a rectangular cross section. Specifically, the fixed frame 5 has a cylindrical body having a trowel-shaped cross section and an annular lid plate 5C.
It is composed by combining. The fixed frame 5 is integrally formed with spokes 5b extending in the radial direction from the boss 5a, and the boss 5a is supported on the rotating shaft 2 by a bearing 4. The fixing frame 5 is fixed to, for example, a gear box of a transmission by suitable means. A large number of ferromagnetic plates (pole pieces) 6 are coupled to both side walls of the fixed frame 5 at equal intervals in the circumferential direction. Preferably, the ferromagnetic plate 6 is cast when the fixed frame 5 is molded.

The inner magnet support ring 8 that supports a large number of permanent magnets 12 is
It is rotatably supported inside the fixed frame 5 by a bearing 7.

The outer magnet support ring 10 is rotatably supported by a bearing 9 on the outer peripheral wall of the inner magnet support ring 8 . Magnet support ring 8,1
Thin sliding plate 14 impregnated with 1IH1I oil on both sides of 0
is sandwiched and slidably contacted with the ferromagnetic plate 6.

As shown in FIG. 2, the inner magnet support ring 8 is made of a non-magnetic material such as aluminum, and has a large number of sector-shaped permanent stones 13 facing the ferromagnetic plate 6 and having a polarity with respect to the ferromagnetic plate 6. They are arranged so that they appear alternately. Preferably, the permanent magnet 12 is cast into the magnet support ring 8 . Similarly, in the outer magnet support ring 10, a large number of permanent magnets 13 are arranged at the same distance from the ferromagnetic plate 6. The pinion 15 of the electric motor 16 fixed to the fixed frame 5 is engaged with the portion 1!1118 formed on the outer circumferential wall of the magnet support ring 10, and the magnet support ring 10 rotates forward and backward by an arrangement pitch of 0 of the permanent magnets 13. It is considered possible. Although not shown, the ferromagnetic plate 6 has a pair of inner and outer permanent magnets 12.1.
It is a fan-shaped one with a wide area covering 3.

Next, the operation of the eddy current speed reduction device according to the present invention will be explained. While a pair of working discs 3 are rotated together with the rotating shaft 2, as shown in FIG. In an arrangement in which the ferromagnetic plates 6 are different from each other, a short-circuit magnetic closed circuit occurs between the pair of ferromagnetic plates 6, and no magnetic field is applied to the brake disc 3. Since the pair of ferromagnetic plates 6 completely sandwich the permanent magnets 12 and 13 from both sides, almost no magnetic flux leaks to the -1 dynamic disk 3.

Therefore, the brake disc 3 is not subjected to any drag torque.

When braking, when the outer magnet support wheel 10 is rotated by the arrangement pitch 0 minute by the electric motor 1116, the inner and outer permanent magnets 12.1
3 have the same polarity with respect to the ferromagnetic plate 6. Therefore, as shown in Figure 3.4, the inner and outer permanent magnets 12.13
equally exert a magnetic field on the brake disk 3 via the ferromagnetic plate 6.

When the rotating brake disc 3 crosses the magnetic field, eddy currents are generated in the brake disc 3, and the brake disc 3 is subjected to a dynamic torque. At this time, as shown in FIG. 4, from each permanent magnet 12.13, the ferromagnetic plate 6, the braking disk 3, the adjacent ferromagnetic plate 6, the adjacent permanent magnet 12.13, the ferromagnetic plate 6 on the opposite side. , a magnetic closed circuit is generated to the opposite braking disk 3 and the adjacent ferromagnetic plate 6.

The ferromagnetic plates 6 on both side walls of the fixed frame 5 are connected to the inner and outer magnet support wheels 8.
．． Due to the rotation differential corresponding to the arrangement pitch of the 10 permanent magnets, a non-braking state in which a short-circuit magnetic closed circuit is formed in the plane including the rotating shaft, and a magnetic closed circuit in which a magnetic field is applied to the brake disc in the plane of the fixed frame 5 are created. to form an active state.

When forming the short-circuit magnetic closed circuit shown in FIG. 1, the magnetic flux density at the radial center of the ferromagnetic plate 6 is denser than at other parts, so increasing the plate thickness at the center will make it more efficient. A short-circuit magnetic 111 circuit is formed, and the leakage magnetic flux reaching the brake disc 3 can be reduced more efficiently.

In the modified embodiment shown in FIG. 5, the thickness of the central part of the ferromagnetic plate 6 is increased, and the permanent magnets 12 and 13 are tapered to be thinner at the part where they touch each other (the part adjacent to the bearing 9). This is what I did.

In the modified embodiment shown in FIG. 6, the ferromagnetic plate 6 is stepped so that the central part is thicker and the inner and outer edges are thinner, which corresponds to the inner surface of the ferromagnetic plate 6. permanent magnet 12
．． 13 has a T-shaped cross section.

In the modified embodiment shown in FIG. 7, the inner surface of the ferromagnetic plate 6 is protruded in an arc shape. In the modified embodiment of FIG. 8, on the contrary, the ferromagnetic plate 6
has a chevron-shaped outer surface, and a v-shaped annular groove 19 is formed in the brake disk 3 in correspondence with the outer surface of the ferromagnetic plate 6.

In addition, in the above-mentioned embodiment, the inner magnet support ring is fixed,
Although the outer magnet support ring is rotated forward and backward by an electric motor by the arrangement pitch of the permanent magnets, it may also be rotated by a fluid pressure actuator, and the inner magnet support ring may be used instead of the outer magnet support ring. You may also rotate.

Further, it is preferable to determine the ratio of the radial dimension of the permanent magnets without changing the arrangement pitch so that the permanent magnets of the outer magnet support ring and the permanent magnets of the inner magnet support ring have approximately the same area.

[Effects of the Invention] As described above, the present invention provides a cylindrical fixed frame made of a non-magnetic material and having an inner cavity with a rectangular cross section, disposed between a pair of brake discs connected to a rotating shaft, A large number of ferromagnetic plates are connected to both side walls of the fixed frame at equal intervals in the circumferential direction, and a pair of inner and outer magnet support rings are supported inside the fixed frame so as to be relatively rotatable. Permanent magnets facing the plates are arranged so that their polarity with respect to the ferromagnetic plates alternates, and the permanent magnets of the inner and outer magnet support wheels are always sandwiched between a pair of ferromagnetic plates. If the polarities of the inner and outer permanent magnets with respect to the ferromagnetic plates are reversed when not braking, a short-circuit magnetic closed circuit occurs between the pair of ferromagnetic plates. Therefore, leakage magnetic flux can be eliminated with the fixing frame having substantially the same dimensions as the conventional example, and drag torque of the brake disc during non-braking can be eliminated without causing a maximum increase in weight.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of the eddy current type deceleration@pupil according to the present invention,
Fig. 2 is a side view of the magnet support wheel, Fig. 3 is a front sectional view showing the eddy current deceleration @ pupil braking state,
FIG. 4 is a developed plane sectional view in the same direction, and FIGS. 5 to 8 are front sectional views showing modified embodiments of the ferromagnetic plate of the fixed frame and the pair of inner and outer magnet support rings. 2: Rotating shaft 3: IITo disk 5: Fixed frame 6 2 ferromagnetic plates 8. 10 2 @ Stone support ring 12, 13: Permanent magnet

Claims (1)

[Claims] A cylindrical fixed frame made of a non-magnetic material and having an inner cavity with a rectangular cross section is arranged between a pair of brake discs connected to a rotating shaft. The ferromagnetic plates are combined, and a pair of inner and outer magnet support rings are supported in a fixed frame so as to be relatively rotatable, and each magnet support ring has a permanent magnet that faces each ferromagnetic plate, and the polarity with respect to the ferromagnetic plates is alternated. An eddy current type reduction device characterized in that the eddy current type reduction gear is arranged differently.