JP2557740Y2 - Structure of fixed frame of eddy current type reduction gear - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention switches between braking and non-braking by projecting or retracting a magnet support cylinder having a plurality of permanent magnets (hereinafter simply referred to as "magnets") on its outer peripheral surface into a braking drum. In particular, the present invention relates to a structure of a fixed frame of an eddy current type reduction gear that is lightweight and effectively prevents magnetic leakage during non-braking.

[0002]

2. Description of the Related Art In an eddy current type speed reducer disclosed in Japanese Patent Application Laid-Open No. 3-86060, one half of a cylindrical fixed frame having a box-shaped inner space is projected into the inside of a braking drum. Further, a large number of ferromagnetic plates are coupled to the outer peripheral wall made of a non-magnetic material at equal intervals in the circumferential direction. On the other hand, the other half of the fixed frame is provided outside the braking drum to constitute a magnetic shielding cylinder made of a ferromagnetic material.
Magnets opposed to the ferromagnetic plates are coupled to the outer peripheral surface of the magnet support cylinder supported in the inner space of the fixed frame so as to be slidable in the axial direction so that the polarities are alternately different in the circumferential direction.

At the time of braking, at the position where each magnet faces the ferromagnetic plate, the magnetic field penetrates the ferromagnetic plate and exerts a magnetic field on the inner peripheral surface of the braking drum. The drum receives a braking force based on the eddy current. When the magnet support cylinder is moved in the axial direction, the magnet faces the magnetic shield cylinder, the magnetic field does not reach the brake drum, and the brake drum does not receive the braking force.

In the above-mentioned eddy current type speed reducer, the magnetic shielding cylinder of the fixed frame is made of cast steel or the like to have a uniform thickness.
It is not preferable in that the weight of the fixed frame is large and it is necessary to reinforce the support structure of the fixed frame to the vehicle body.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a structure of a fixed frame of an eddy current type reduction gear which is lightweight and can effectively prevent magnetic leakage during non-braking. It is in.

[0006]

In order to achieve the above-mentioned object, according to the present invention, an end of a box-shaped annular fixed frame made of a non-magnetic material is inserted into a brake drum connected to a rotating shaft. A magnet support tube that protrudes from the side and is connected to ferromagnetic plates at a number of openings provided at equal intervals in the circumferential direction on the outer peripheral wall of the fixed frame and is slidably supported in the inner space of the fixed frame having a box-shaped cross section. A permanent magnet is connected to the outer peripheral surface of the fixed frame so as to oppose each ferromagnetic plate and alternately have a different polarity in the circumferential direction. The inner peripheral surface of the magnetic shielding cylinder facing each permanent magnet is a cylindrical surface, and the thickness of the portion of each permanent magnet facing the center in the circumferential direction is reduced, so that the space between the adjacent permanent magnets is reduced. The thickness of the opposing portion is increased.

[0007]

According to the present invention, one half of the fixed frame in the axial direction (a portion protruding into the brake drum) is made of a non-magnetic material, and a large number of ferromagnetic plates are embedded in the outer peripheral wall. The other half in the axial direction of the fixed frame is configured as a magnetic shielding cylinder made of a strong magnetic material. The inner peripheral surface of the magnetic shielding cylinder is a cylindrical surface,
The outer peripheral surface is formed with a thick portion and a thin portion, for example, by providing a large number of axial grooves, and is configured such that the thick portion faces a space between magnets adjacent in the circumferential direction.

By removing extraneous material on the outer peripheral side of the magnetic shield cylinder, a cross section corresponding to the magnetic flux density of the short-circuit magnetic circuit formed between the magnetic shield cylinder and the magnet support cylinder during non-braking is formed. Magnetic leakage to the outside can be prevented, and the fixed frame can be made lightweight.

[0009]

FIG. 3 is a side sectional view showing a schematic configuration of an eddy current type speed reducer according to the present invention. The eddy current type speed reducer includes a braking drum 4 and a magnet support cylinder 8. A mounting flange 2 is spline-fitted to an output rotary shaft 1 protruding from an end wall of the vehicle transmission and fastened by a nut 1a.
The end wall of the brake drum 3 of the parking brake and the flange portion 4a of the brake drum 4 of the reduction gear are overlapped on the mounting flange 2, and fastened with a plurality of bolts 5 and nuts. Numerous spokes 4b projecting radially outward from flange 4a
, The edge 4c of the braking drum 4 is connected. A large number of cooling fins 7 are provided on the outer peripheral surface of the braking drum 4 at equal intervals in the circumferential direction.

A cylindrical fixed frame 9 having an inner space 17 having a box-shaped cross section is arranged inside the braking drum 4 made of a conductor. The fixed frame 9 is fixed to the end wall of the transmission by an appropriate means, and may be formed by connecting annular end wall plates to both ends of the outer cylinder and the inner cylinder. A magnetic shielding cylinder 16 having a U-shaped cross section in the left half made of a magnetic material such as iron and a cylindrical frame having an inverted L-shaped cross section made of a non-magnetic material such as aluminum are provided outside the braking drum 4. The part 15 is connected with a number of bolts 18. Numerous openings are provided at equal intervals in the circumferential direction in the outer cylindrical portion of the fixed frame 9 facing the inner circumferential surface of the braking drum 4, that is, the outer circumferential wall of the frame portion 15, and the ferromagnetic plate 14 is fitted and fixed in each opening. You.

A plurality (preferably three) of actuators 10 are supported on the fixed frame 9 at equal intervals in the circumferential direction. The actuator 10 has a piston 12 fitted to a cylinder 11, and a rod 13 extending from the piston 12 to the inner space of the fixed frame 9 is connected to the magnet support cylinder 8. The magnet support tube 8 is supported by the guide wall 16a of the fixed frame 9 so as to be movable in the axial direction.
The outer peripheral surface of the magnet support tube 8 is connected to a large number of magnets 6 facing each ferromagnetic plate 14 so that the polarities are alternately different in the circumferential direction.

At the time of braking, when pressurized air is supplied to the left end chamber of the actuator 10, the magnet support cylinder 8 is pushed rightward along the guide wall 16a by the piston 12 via the rod 13 as shown in FIG. In addition, the magnet 6 overlaps the ferromagnetic plate 14. The rotating braking drum 4 is moved from the magnet 6 to the ferromagnetic plate 14.
When an eddy current flows through the brake drum 4 when the magnetic field passes through the brake drum 4, the brake drum 4 receives a braking torque. During braking, the magnet 6 and the ferromagnetic plate 14 overlap each other and are located between the braking drum 4 and the magnet support tube 8 to form a magnetic circuit indicated by a chain line x in FIG.

When pressurized air is supplied to the right end chamber of the actuator 10 during non-braking, the rod 13
, The magnet support tube 8 is pulled to the left along the guide wall 16a, and as shown in FIG. 1, the magnet 6 is an outer wall portion of the magnetic shield tube 16 of the fixed frame 9 made of a magnetic material, that is, a magnetic shield. Cylinder 16
Oppose. At the time of braking, the magnet 6 is provided between the magnetic shielding tube 16 and the magnet supporting tube 8 to form a short-circuit magnetic circuit indicated by a chain line y in FIG. 3 and does not apply a magnetic field to the braking drum 4.

According to the present invention, in order to reduce the weight of the fixed frame 9, the inner peripheral surface 16d of the magnetic shielding cylinder 16 is a cylindrical surface, and the outer peripheral surface is provided with a large number of axial grooves to form a thick portion 16b. A thin portion 16c is formed. That is, corresponding to the magnetic flux density of the short-circuit magnetic circuit indicated by the chain line y, the thick portion 16b faces the space 31 between the magnets 6 adjacent in the circumferential direction, and the thin portion 1b.
6c is configured to face the center of each magnet 6 in the circumferential direction. The structure of the above-mentioned magnetic shielding cylinder 16 can be integrally formed by casting.

In the present invention, as described above, the magnetic shield cylinder 16 is not made uniform in thickness, but is configured to have a thickness corresponding to the magnetic flux density of the short-circuit magnetic circuit when braking is not performed. 16, the weight of the fixed frame 9 can be reduced
That is, the support structure for supporting the transmission wall can be simplified.

In the embodiment shown in FIG. 4, the inner peripheral surface of the magnetic shielding cylinder 16 is a cylindrical surface, the outer peripheral surface is a polygonal cross section, and the thickness of the portion of each magnet 6 facing the center in the circumferential direction is thin. The thickness of the portion facing the space 31 between the magnets 6 adjacent in the circumferential direction is increased. The magnetic shield tube 16 is easily machined.

In the embodiment shown in FIG. 5, as an alternative to the magnetic shielding cylinder 16, a magnetic shielding member 27b made of an elongated magnetic material having a substantially triangular cross section is cast into a cylindrical body 27a made of lightweight aluminum. Thus, a cylindrical magnetic shielding cylinder 27 having a substantially uniform thickness is formed. The inner peripheral surface of each magnetic shielding member 27b forms a cylindrical surface, and the thick portion of each shielding member 27b is formed in the space 3 between the magnets 6 adjacent in the circumferential direction.
1, the thin portions on both side edges of the magnetic shielding member 27b face the center of the magnet 6 in the circumferential direction.

[0018]

According to the present invention, as described above, one end of a cylindrical fixed frame made of a non-magnetic material and having a box-shaped cross section is projected into the inside of the braking drum connected to the rotating shaft, and the outer peripheral wall of the fixed frame is formed. The ferromagnetic plates are connected to a large number of openings provided at equal intervals in the circumferential direction, and each ferromagnetic plate is mounted on the outer peripheral surface of a magnet supporting cylinder which is slidably supported in the box-shaped inner space of the fixed frame in the axial direction. The permanent magnets which are opposite to each other and have different polarities in the circumferential direction are connected to each other, and the outer peripheral wall protruding from the braking drum of the fixed frame to the outside is formed as a magnetic shielding cylinder made of a magnetic material. The inner peripheral surface opposed to the cylindrical surface is a cylindrical surface, and the thickness of the portion facing the central portion in the circumferential direction of each permanent magnet is reduced, and the thickness of the portion facing the space between adjacent permanent magnets is increased. Because
The cross section of the magnetic shielding cylinder corresponds to the magnetic flux density of the short-circuit magnetic circuit during non-braking, preventing magnetic leakage to the outside and reducing the weight of the fixed frame.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a fixed frame taken along line 1A-1A of FIG. 3 showing an eddy current type speed reducer according to the present invention.

FIG. 2 is a front sectional view of the fixing frame, taken along line 2A-2A in FIG. 3;

FIG. 3 is a side sectional view of the eddy current speed reducer according to the present invention.

FIG. 4 is a front sectional view of a fixing frame according to a partially modified embodiment of the present invention.

FIG. 5 is a front sectional view of a fixing frame according to another partially modified embodiment of the present invention.

[Explanation of symbols]

1: rotating shaft 4: braking drum 6: permanent magnet 9: fixed frame 10: actuator 14: ferromagnetic plate 15: frame portion 16: magnetic shielding cylinder 16b: thick portion 16b: thin portion 17: inner space portion

Claims (1)

(57) [Scope of request for utility model registration] An annular fixed frame made of a non-magnetic material and having a box-shaped cross section protrudes into the inside of a brake drum connected to a rotating shaft, and is provided on an outer peripheral wall of the fixed frame at equal circumferential intervals. A ferromagnetic plate is coupled to the opening of the magnet support cylinder, and the outer peripheral surface of the magnet support cylinder slidably supported in the box-shaped inner space of the fixed frame in the axial direction. Permanent magnets are connected alternately differently, and the outer peripheral wall protruding from the braking drum of the fixed frame to the outside is configured as a magnetic shielding cylinder made of a magnetic material. Eddy current type, characterized in that the thickness of the portion facing the central portion in the circumferential direction of each permanent magnet is reduced, and the thickness of the portion facing the space between adjacent permanent magnets is increased. Structure of fixed frame of reduction gear.