JPH07118904B2 - Eddy current type speed reducer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an eddy current type speed reducer for assisting a friction brake of a large vehicle, and in particular, an eddy current equipped with means for switching a magnet supporting ring between a braking position and a non-braking position inside a fixed frame. Type speed reducer.

[0002]

2. Description of the Related Art In an eddy current type speed reducer disclosed in Japanese Patent Application Laid-Open No. 1-298948, a fixed frame having a box-shaped inner cross section made of a non-magnetic material is arranged inside a braking drum.
A large number of ferromagnetic plates facing the inner peripheral surface of the braking drum are connected to the outer cylinder of the fixed frame at equal intervals in the circumferential direction, and a magnet support ring is rotatably supported in the inner space of the fixed frame to support the magnet. A permanent magnet facing each ferromagnetic plate is coupled to the ring so that the polarities thereof are alternately different in the circumferential direction.

When the magnet support ring is rotated by the hydraulic actuator so that the permanent magnet overlaps the ferromagnetic plate, a magnetic circuit is generated between the braking drum and the magnet support ring, and the magnetic field acting from the permanent magnet to the braking drum is generated. When the braking drum crosses over, the eddy current flows in the braking drum, and the braking drum receives the braking torque. On the other hand, when the magnet support ring is rotated by half of the arrangement interval of the permanent magnets by the hydraulic actuator, the two permanent magnets arranged in the circumferential direction partially oppose one ferromagnetic plate, and the ferromagnetic plate and the magnet supporting ring are partially opposed. The braking drum receives no braking torque because a short-circuiting magnetic circuit is created between it and the ring, and the magnetic field does not act on the braking drum.

In the above-mentioned eddy current type speed reducer, since the hydraulic actuator is used to obtain the switching operation by the forward and reverse rotation of the magnet support ring, the entire device becomes long, and the magnet support ring and the fixed frame are provided. Since the arm protruding to the outside through the slit is connected to the hydraulic actuator, the sealing mechanism for the gap between the movable part of the arm and the slit of the fixed frame becomes complicated, and when foreign matter enters the fixed frame from the outside, It adheres to the permanent magnets and hinders smooth operation.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is that the structure is simple and can be arranged inside the fixed frame,
(EN) An eddy current type speed reducer that obtains a switching operation between braking and non-braking by forward / reverse rotation of a magnet supporting ring by using a permanent magnet of the magnet supporting ring.

[0006]

In order to achieve the above object, the structure of the present invention is such that an annular fixed frame having a box-shaped cross section is arranged inside a braking drum connected to a rotating shaft, and A large number of ferromagnetic bodies are coupled to the outer cylindrical portion of the fixed frame facing the inner peripheral surface at equal intervals in the circumferential direction, and each of them is attached to a magnet support ring made of a magnetic body rotatably supported in the inner space of the fixed frame. Two permanent magnets are connected to the ferromagnetic body so that the polarities of the magnetic poles facing the ferromagnetic body are two circumferentially different, and the permanent magnets of the magnet support ring are opposed to the outer cylinder of the fixed frame. By arranging at least one electromagnet and reversing the magnetic poles of the magnetic poles facing the permanent magnets of the electromagnets, the polarities of the two magnetic poles of the permanent magnets facing each ferromagnetic material are the same as the braking position and the strong magnetic poles. At the non-braking position where the two magnetic poles of the permanent magnet facing the magnetic body have different polarities, the magnet support ring is provided. It is obtained so as to rotate.

[0007]

In the magnet support ring, U-shaped permanent magnets or block-shaped permanent magnets are arranged so that the polarities of the magnetic poles are different from each other in the circumferential direction.

When the electromagnet facing the permanent magnet is arranged in the outer cylinder portion of the fixed frame and the electromagnet is excited to give the electromagnet a polarity opposite to that of the permanent magnet, the repulsive force between the two causes the magnet support ring to rotate. Then, when the adjacent permanent magnets having different polarities are attracted to the electromagnet, the operation is stopped. Here, when the electromagnet is provided with a polarity opposite to that of the permanent magnet, the repulsive force between the two causes the magnet support ring to rotate in the opposite direction, and the adjacent permanent magnets having different polarities are stopped when they are attracted to the electromagnet.

In this way, a pair of permanent magnets having different magnetism face one ferromagnetic body, generate a short-circuit magnetic circuit between the pair of permanent magnets, and a non-braking state in which a magnetic field is not applied to the braking drum, and a magnetic state. It is possible to switch to a braking position in which a pair of permanent magnets different from each other straddles two adjacent ferromagnetic bodies and exerts a magnetic field on the braking drum via the ferromagnetic bodies.

[0010]

FIG. 1 is a front sectional view showing an embodiment in which an eddy current type speed reducer according to the present invention is arranged at a rear end portion of a vehicle transmission. A mounting flange 7 is spline-fitted to an output rotary shaft 4 supported by a bearing 3 on the rear end wall of the transmission 2, and is fastened by a nut 5. An end wall of a braking drum 16 of a known parking brake and an end wall 10 of a braking drum 13 of a speed reducer are superposed on the mounting flange 7 and fastened by a plurality of bolts 8 and nuts 9. A yoke 6 of a universal joint for connecting the rotating shaft 4 and a known propulsion shaft is fitted to a mounting flange 7 and joined by a bolt (not shown). The braking drum 13 is provided with a large number of cooling fins 12 on the outer peripheral wall at equal intervals in the circumferential direction.

The inner peripheral surface of the braking drum 13 and the braking drum 16
An annular fixed frame 20 made of a non-magnetic material and having a box-shaped cross section is disposed in a space between the outer peripheral surface and the outer peripheral surface. Therefore, the annular frame plate 15 having the reinforcing ribs 15 a is fixed to the rear end wall of the transmission 2 via the mounting plate 14, and the end wall 21 of the fixed frame 20 is fixed to the wall plate 17 connected to the frame plate 15. Is fixed. The fixed frame 20 is formed by connecting end walls 21 and 22 made of annular plates to both ends of the outer tubular portion 23 and the inner tubular portion 24 to form an inner hollow portion having a box-shaped cross section. A magnet support ring 27 made of a magnetic material (a non-magnetic material may be used in the illustrated embodiment) is provided in the inner space of the fixed frame 20 in the bearing 1.
It is rotatably supported by 8.

As shown in FIG. 3, the outer cylinder portion 2 of the fixed frame 20.
A large number of rectangular openings are provided at 3 at equal intervals in the circumferential direction, and the ferromagnetic material 25 is fitted and fixed in each opening. The side surface cross section (cross section perpendicular to the rotation axis 4) of the ferromagnetic body 25 has an inverted V shape for weight reduction, and is provided with a pair of leg pieces that are open in the circumferential direction at the inner end portion. A U-shaped permanent magnet 26 having magnetic poles corresponding to the leg pieces of each ferromagnetic body 25 is coupled to the magnet support ring 27. U
The magnetic poles of the shaped permanent magnet 26 are arranged so that their magnetism differs by two in the circumferential direction. Instead of the U-shaped permanent magnet 26, a block-shaped permanent magnet may be used, and the magnetic poles of the permanent magnets are arranged so as to differ by two in the circumferential direction.

As shown in FIG. 3, the outer cylinder portion 2 of the fixed frame 20.
3, three electromagnets 31 lined up in the circumferential direction so as to be able to face the magnetic poles of the permanent magnet 26 side by side with the ferromagnetic body 25 in the axial direction.
a to 31c are combined. As shown in FIG. 1, the electromagnet 3
1a to 31c are arranged in a portion where the wall thickness of the outer cylinder portion 23 in the left half portion of the fixed frame 20 is thin. Preferably, the fixed frame 20
Between the magnet support ring 27 and the magnet support ring 27, a stopper for limiting the rotation range of the magnet support ring 27 to half the arrangement interval p of the ferromagnetic bodies 25 or a ratchet mechanism is provided.

Further, the ferromagnetic body 25 and the outer cylinder portion 23 and the permanent magnet 26 and the magnet support ring 27 are integrally joined or cast when molding from metal or synthetic resin, respectively. The electromagnets 31a to 31c may be disposed between the ferromagnetic bodies 25 and 25 of the outer tubular portion 23 at the expense of one ferromagnetic body 25.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. When the magnet support ring 27 is brought into the non-braking state shown in FIG. 3, the pair of magnetic poles of each U-shaped permanent magnet 26 opposes the pair of leg pieces of one ferromagnetic body 25. Since a short-circuit magnetic circuit shown by a chain line is generated between the ferromagnetic body 25 and the ferromagnetic body 25 and no magnetic field is exerted on the braking drum 13, the braking drum 13 receives no braking torque.

When the magnet support ring 27 is brought into the braking state shown in FIG. 4, the pair of magnetic poles of each permanent magnet 26 straddles the leg pieces of two ferromagnetic bodies 25 adjacent in the circumferential direction. That is, since the magnetic poles of the same polarity face the pair of leg pieces of each ferromagnetic body 25,
Each permanent magnet 26, a pair of ferromagnetic bodies 25, and the braking drum 13
A magnetic circuit indicated by a chain line is generated between and. When the rotating braking drum 13 traverses a magnetic field acting from the permanent magnet 26 to the braking drum 13 via the ferromagnetic body 25, the braking drum 1
An eddy current flows through the brake drum 3, and the brake drum 13 receives a brake torque.

The switching operation between non-braking and braking by the rotation of the magnet support ring 27 can be achieved by the electromagnets 31a to 31c as follows. In the non-braking state shown in FIG. 3, the electromagnet 31b at the center is excited, and the magnetic pole of the electromagnet 31b facing the magnetic pole N of the permanent magnet 26a (the permanent magnet involved in the electromagnet is particularly 26a) is S. Here, in order to rotate the magnet support ring 27 in the counterclockwise direction from the non-braking state shown in FIG. 3 to the braking state shown in FIG. 4, first, the electromagnet 31b is demagnetized and the electromagnet 31c is excited to set the magnetic pole to N. Then, the magnetic pole S of the permanent magnet 26a is attracted to the electromagnet 31c, and the magnetic pole N is repelled and faces the demagnetized electromagnet 31a. Next, when the electromagnet 31c is demagnetized and the electromagnet 31b is excited to set the magnetic pole to N, the magnetic pole S of the permanent magnet 26a is attracted to the electromagnet 31b and the braking state shown in FIG. 4 is established.

On the contrary, in order to rotate the magnet support ring 27 in the clockwise direction from the braking state shown in FIG. 4 to the non-braking state shown in FIG. 3, first, the electromagnet 31a is excited to set the magnetic pole to S. The magnetic pole N of the magnet 26a is attracted to the electromagnet 31a, and the magnetic pole S opposes the repelled and demagnetized electromagnet 31c. Next, when the electromagnet 31a is demagnetized and the electromagnet 31b is excited to set the magnetic pole to S, the magnetic pole N of the permanent magnet 26a is attracted to the electromagnet 31b and the non-braking state shown in FIG. 3 is obtained.

In the embodiment shown in FIG. 5, one electromagnet 32 is connected to the outer cylinder portion 23 of the fixed frame 20. When the magnet support ring 27 is rotated counterclockwise by half the arrangement interval of the ferromagnetic bodies 25, the electromagnet 32 is excited and the permanent magnet 2 is excited.
When the magnetic pole facing 6a is set to N, the magnetic pole N of the permanent magnet 26a is repelled and the magnetic pole S is attracted to the electromagnet 32. When the magnet support ring 27 is rotated clockwise from this state by a half of the arrangement interval of the ferromagnetic bodies 25, when the electromagnet 32 is excited to set the magnetic pole facing the permanent magnet 26a to S, the magnetic pole of the permanent magnet 26a. S is repelled, the magnetic pole N is attracted to the electromagnet 32, and the state returns to the illustrated state.

The embodiment shown in FIG. 6 has two ferromagnetic bodies 25.
A coil is wound around each leg of the electromagnet 33
a and 33b are configured. In the illustrated state, the electromagnets 33a and 33b are excited and the magnetic pole of the electromagnet 33a is set to N.
When the magnetic pole of the electromagnet 33b is S, the magnet support ring 27
Is rotated counterclockwise, the magnetic pole S of the permanent magnet 26a is attracted to the electromagnet 33a, and the magnetic pole N of the right adjacent permanent magnet 26b is attracted to the electromagnet 33b.

To return the magnet support ring 27 to the state shown in FIG. 6, when the magnetic pole of the electromagnet 33a is set to S and the magnetic pole of the electromagnet 33b is set to N, the magnet support ring 27 is rotated clockwise.
The magnetic pole N of the permanent magnet 26a is attracted to the electromagnet 33a, and the magnetic pole S of the right adjacent permanent magnet 26b is attracted to the electromagnet 33b.

[0022]

As described above, according to the present invention, the electromagnet that exerts the attractive force and the repulsive force on the permanent magnet of the magnet support ring is arranged in the fixed frame. Therefore, by changing the direction of the electric current applied to the electromagnet, The magnet support ring can be rotated forward and backward.

Since it suffices to pull out the conductive wire of the electromagnet to the outside of the fixed frame, the inner space of the fixed frame can be kept airtight, the deterioration of the performance of the permanent magnet due to the intrusion of rainwater, etc. can be prevented, and the permanent magnet is strong. Since it has a magnetic force, a large rotational force can be applied to the magnet support frame by simply applying a slight current to the electromagnet, and the power consumption of the battery is small.

[Brief description of drawings]

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

FIG. 2 is a front sectional view of another portion of the fixed frame of the eddy current type speed reducer.

FIG. 3 is a side sectional view showing the non-braking state of the same eddy current type speed reducer.

FIG. 4 is a side sectional view showing a braking state of the eddy current type speed reducer.

FIG. 5 is a side sectional view of an eddy current type speed reducer according to a second embodiment of the present invention.

FIG. 6 is a side sectional view of an eddy current type speed reducer according to a third embodiment of the present invention.

[Explanation of symbols]

4: rotating shaft 13: braking drum 20: fixed frame 25:
Ferromagnetic material 26: Permanent magnet 27: Magnet support ring 31a
~ 31c, 32, 33a, 33b: Electromagnet

Claims (1)

[Claims] 1. An annular fixing frame having a box-shaped cross section is arranged inside a braking drum connected to a rotating shaft, and a large number of ferromagnetic bodies are provided in an outer cylinder portion of the fixing frame facing the inner peripheral surface of the braking drum. To the magnet support ring made of a magnetic material that is rotatably supported in the inner space of the fixed frame by coupling the magnets at equal intervals in the circumferential direction. Permanent magnets are coupled so that the polarities are different by two in the circumferential direction, and at least one electromagnet facing the permanent magnet of the magnet support ring is disposed in the outer cylinder portion of the fixed frame and faces the permanent magnet of the electromagnet. By reversing the magnetic poles of the magnetic poles, the polarities of the two magnetic poles of the permanent magnets facing the ferromagnetic bodies are the same, and the polarities of the two magnetic poles of the permanent magnets facing the ferromagnetic bodies are different. An eddy current type speed reducer characterized by rotating a magnet support ring to a position.