JPH0617386U - Eddy current type speed reducer - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a lightweight device without affecting the magnetic circuit. [Structure] Inside the braking drum 7 connected to the rotary shaft 1,
A fixed cylinder 10 having a box-shaped cross section made of a non-magnetic material is arranged. A large number of ferromagnetic plates 15 are coupled to the outer peripheral wall 10a of the fixed cylinder 10 at equal intervals in the circumferential direction. Each ferromagnetic plate 15 is attached to a magnet support cylinder 14 rotatably supported in an inner space of the fixed cylinder 10 having a rectangular cross section.
The permanent magnets 24 are coupled so that the polarities of the ferromagnetic plates 15 are alternately different in the circumferential direction. An axial groove 22 is provided in a portion of the inner peripheral wall of the magnet supporting cylinder 14 corresponding to the center of the magnets 24 in the circumferential direction to reduce the weight of the magnet supporting cylinder 14.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is mainly an eddy current type speed reducer for assisting a friction brake of a large vehicle, and in particular, a braking drum that rotates a large number of permanent magnets (hereinafter simply referred to as magnets) arranged side by side at equal intervals in a magnet supporting cylinder during braking. The present invention relates to an eddy current type speed reducer that brings a braking torque based on an eddy current to a braking drum by approaching the inner peripheral surface of the.

[0002]

[Prior art]

 Japanese Unexamined Patent Publication No. 3-86060 discloses an eddy current type speed reducer that applies a braking torque to a braking drum by bringing a number of permanent magnets lined up at equal intervals in the circumferential direction on the inner surface of a rotating braking drum. In this way, the magnet support cylinder is moved in the axial direction inside the fixed cylinder so that each magnet of the magnet support cylinder is entirely opposed to the ferromagnetic plate (pole piece) of the fixed cylinder during braking, while it is not braked. As disclosed in Japanese Patent Application No. 2-112026, a magnet support cylinder is rotated inside a fixed cylinder to allow each magnet to retreat from a ferromagnetic plate, and There is a type in which the magnets are entirely opposed to the ferromagnetic plate of the fixed cylinder, while the magnets adjacent to each other during non-braking are partially opposed to the common ferromagnetic plate.

In any case, since the magnet supporting cylinder made of a magnetic material serves as a yoke to form a magnetic circuit between the braking drum sandwiching the magnet and the magnet supporting cylinder, a considerable thickness is required. To be done. However, the thick magnet support cylinder not only increases the weight of the magnet support cylinder, but also increases the weight of the fixed cylinder that guides and supports the magnet support cylinder in terms of strength.

[0004]

[Problems to be solved by the device]

 In view of the above problems, it is an object of the present invention to provide an eddy current type speed reducer that does not affect the magnetic circuit and realizes weight reduction of the device.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the structure of the present invention has a fixed cylinder having a rectangular cross-section inner space inside the braking drum, and a large number of ferromagnetic plates at equal intervals in the circumferential direction on the outer peripheral wall of the fixed cylinder. A permanent magnet with one magnetic pole facing each ferromagnetic plate and having different polarities alternately in the circumferential direction is connected to the outer peripheral surface of the magnet supporting cylinder made of a magnetic material that is placed and supported in the inner space of the fixed cylinder. However, each permanent magnet is equipped with a means for driving the magnet supporting cylinder to a braking position where the permanent magnet is entirely opposed to the ferromagnetic plate and a non-braking position where it is not opposed to the permanent magnet. The thickness of the corresponding part is thinner than the other parts.

[0006]

[Action]

 Focusing on the magnetic circuit formed between the braking drum and the magnet support cylinder with the magnet sandwiched, there is a useless flesh portion that is hardly involved in the magnetic circuit in the inner peripheral wall of the magnet support cylinder. The present invention reduces the weight of the magnet support cylinder by providing an axial groove on the inner peripheral wall of the magnet support cylinder to reduce the thickness of the portion of the magnet support cylinder that corresponds to the circumferential center of each magnet. Is.

When casting the magnet support cylinder, it is possible to reduce the weight by offsetting the magnet support cylinder to the inner peripheral wall of the magnet support cylinder and providing an axial hole in the portion corresponding to the circumferential center of each magnet. Since the cylindrical surface remains inside the cylinder, it is advantageous for the eddy current type speed reducer of the type in which the magnet supporting cylinder is rotated to switch between braking and non-braking.

[0008]

【Example】

 FIG. 1 is a side sectional view of an eddy current type speed reducer of a type in which a magnet supporting cylinder according to the present invention is rotated inside a fixed cylinder to switch between braking and non-braking, and FIG. 2 is a front sectional view of the same. . The eddy current type speed reducer according to the present invention is, for example, a stationary guide formed of a braking drum 7 made of a conductor coupled to an output rotary shaft 1 of a vehicle transmission, and a non-magnetic body arranged inside the braking drum 7. The cylinder 10 and a magnet support cylinder 14 rotatably supported in the inner space of the guide cylinder 10 having a rectangular cross section are provided. The braking drum 7 is such that the flange portion 5a of the boss 5 and the end wall portion of the braking drum 3 of the parking brake are superposed on the mounting flange 2 which is spline-fitted and fixed to the rotary shaft 1, and the plurality of bolts 4 and nuts. It is concluded by. One end of a braking drum 7 having a cooling fin 8 is connected to a large number of spokes 6 extending radially from the boss 5.

The fixed cylinder 10 having a box-shaped cross section is configured by, for example, connecting a ring-shaped cover plate 11 to a cylindrical body having a C-shaped cross section. The fixed barrel 10 is fixed to the gear box of the transmission by any suitable means. A large number of ferromagnetic plates 15 are coupled to the outer peripheral wall 10a of the fixed barrel 10 at equal intervals in the circumferential direction. Preferably, the ferromagnetic plate 15 is cast around when the fixed cylinder 10 is molded. The ferromagnetic plate 15 has a rectangular plate shape, and the plate surface is curved in an arc shape. The peripheral wall of the ferromagnetic plate 15 is integrally formed with the ridge 25 to enhance the degree of coupling between the outer peripheral wall 10a of the fixed barrel 10 and the ferromagnetic plate 15 by casting. The magnet support cylinder 14 is rotatably supported by the bearing 12 on the inner space of the fixed cylinder 10, specifically, on the inner peripheral wall 10b.

Three fluid pressure actuators 20, preferably, are connected to the left end wall of the fixed barrel 10 at equal intervals in the circumferential direction. The fluid pressure actuator 20 has a piston 17 fitted in a cylinder 18, and a rod protruding from the piston 17 is an arm protruding from the magnet supporting cylinder 14 through an arc-shaped slit 18a of the left end wall of the fixed cylinder 10. It is connected to 16.

As shown in FIG. 2, one magnet 24 is coupled to each ferromagnetic plate 15 of the magnet support cylinder 14. The magnet support cylinder 14 is made of a magnetic material, and the magnets 24 facing the ferromagnetic plates 15 are arranged so that their polarities are alternately different in the circumferential direction.

According to the present invention, a V-shaped groove 22 extending in the axial direction is provided in a portion of the inner peripheral wall of the magnet supporting cylinder 14 corresponding to the center of the magnets 24 in the circumferential direction. In other words, the present invention reduces the weight of the magnet supporting cylinder 14 by forming a thin portion on the inner peripheral wall of the magnet supporting cylinder 14 at the portion corresponding to the center of the magnet 24 in the circumferential direction. In the eddy current type speed reducer of the type in which braking and non-braking are switched by rotating the magnet supporting cylinder 14 shown in the figure, the inner cylindrical surface of the magnet supporting cylinder 14 is cut out by the groove 22. Since the magnet 24 rotates forward and backward by the half-arranged pitch of the magnet 24, there is no particular problem even if an empty space is formed between the outer ring of the bearing 12 and the groove 22.

As shown in FIG. 4, when the magnet support cylinder 14 is cast, an axial hole is formed in a portion corresponding to the inner circumferential wall of the magnet support cylinder 14 and corresponding to the circumferential center of each magnet 24. Even if 23 is provided, the weight can be reduced, and since the cylindrical surface remains inside the magnet supporting cylinder 24, no special consideration is required for the bearing portion of the magnet supporting cylinder 14.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. At the time of braking, as shown in FIG. 2, each magnet 24 entirely faces each ferromagnetic plate 15 and forms a magnetic circuit 26 between the magnet support cylinder 14 and the braking drum 7. When the rotating braking drum 7 crosses the magnetic field, an eddy current flows in the braking drum 7, and the braking drum 7 receives a braking torque. Since the circumferential position of the groove 22 is located at the circumferential center of each magnet and is located on the inner circumferential wall of the magnet support cylinder 14, the magnetic resistance of the magnetic circuit 26 increases and the number of magnetic fluxes of the magnetic circuit 26 decreases. There is no adverse effect, and therefore the braking ability does not decrease.

When the magnet support cylinder 14 is rotated by the half-aligned pitch of the ferromagnetic plate 15 by the fluid pressure actuator 20 during non-braking, the two magnets 24 having different polarities are partially moved as shown in FIG. It faces each ferromagnetic plate 15. A short-circuit magnetic circuit 27 is generated between each ferromagnetic plate 15 and the magnet support cylinder 14, and the magnet 24 does not apply a magnetic field to the braking drum 7.

The present invention is not limited to the eddy current type speed reducer of the above-mentioned type, but an eddy current type speed reducer of the type disclosed in Japanese Patent Application No. 2-112026 and Japanese Patent Laid-Open No. 3-86060. It can also be applied to devices.

[0017]

[Effect of device]

 According to the present invention, as described above, a fixed cylinder having an inner space with a rectangular cross section is arranged inside the braking drum, and a large number of ferromagnetic plates are arranged at equal intervals in the circumferential direction on the outer peripheral wall of the fixed cylinder. On the outer peripheral surface of the magnet supporting cylinder made of a magnetic material supported in the inner space of the cylinder, one permanent magnet with one magnetic pole facing each ferromagnetic plate and the polarities alternating with each other in the circumferential direction is coupled to each permanent magnet. A means for driving the magnet supporting cylinder to a braking position that entirely opposes the ferromagnetic plate and a non-braking position that does not oppose the ferromagnetic plate is provided, and the thickness of the portion of the inner peripheral wall of the magnet supporting cylinder that corresponds to the circumferential center of each magnet is adjusted. Since it is thinner than the other parts, not only can the weight of the magnet support cylinder be reduced, but the strength of the fixed cylinder that guides and supports the magnet support cylinder is lightened, and the weight of the entire device can be reduced.

Since the circumferential position of the thin portion is located at the circumferential center of each magnet and is located on the inner circumferential wall of the magnet supporting cylinder, the magnetic resistance of the magnetic circuit increases and the number of magnetic fluxes in the magnetic circuit decreases. There is no adverse effect and therefore braking capacity does not decrease.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an upper half of an eddy current type speed reducer according to the present invention.

FIG. 2 is a front cross-sectional view showing braking of the reduction gear transmission taken along the line 2A-2A in FIG.

FIG. 3 is a front sectional view showing the speed reducer when not braking.

FIG. 4 is a front sectional view of a speed reducer according to a modified embodiment of the present invention.

[Explanation of symbols]

1: rotating shaft 7: braking drum 10: fixed cylinder 10a:
Outer peripheral wall 14: Magnet support cylinder 15: Ferromagnetic plate 15b:
Rear end 24: Magnet

Claims (1)

[Scope of utility model registration request] Claims: 1. A fixed cylinder having a rectangular inner section having a rectangular cross section is arranged inside the braking drum, and a large number of ferromagnetic plates are arranged on the outer peripheral wall of the fixed cylinder at equal intervals in the circumferential direction. On the outer peripheral surface of a magnet supporting cylinder made of a magnetic material supported in the empty space, permanent magnets with one magnetic pole facing each other and alternating polarities alternately in the circumferential direction are coupled to each ferromagnetic plate, and each permanent magnet is connected to the ferromagnetic plate. A means for driving the magnet support cylinder to a braking position that is entirely opposed to and a non-braking position that is not opposed, and the wall thickness of the inner peripheral wall of the magnet support cylinder corresponding to the circumferential center of each magnet An eddy current type speed reducer characterized by being made thinner.