JP3719338B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current reduction device for reducing the burden of a friction brake on a large vehicle or the like, and more particularly to an eddy current reduction device in which a magnetic flux of a permanent magnet (hereinafter simply referred to as a magnet) works effectively on a braking drum. It is.
[0002]
[Prior art]
The shape of the side cross section of the ferromagnetic plate arranged in the guide cylinder in the conventional eddy current reduction device is rectangular, the area of the outer surface and the inner surface is almost the same, and the magnetic flux from the magnet is reduced by the ferromagnetic plate. Without reaching the braking drum. Further, in an eddy current reduction device in which a stationary magnet support tube and a movable magnet support tube are arranged in the axial direction inside the guide tube, a non-braking magnet in which magnets of different polarities are opposed to a common ferromagnetic plate In order to suppress drag torque due to leakage magnetic flux from the magnetic field, the ferromagnetic plate must be thickened. Similarly, as disclosed in JP-A-10-127039, even when the shape of the front cross section of the ferromagnetic plate is a trapezoid, the ferromagnetic plate has to be thickened.
[0003]
[Problems to be solved by the invention]
The object of the present invention is to reduce the eddy current deceleration that increases the magnetic flux density by increasing the magnetic flux density by concentrating the magnetic flux from the magnet to the braking drum, particularly in the middle speed rotation range of the braking drum, and increasing the eddy current generated in the braking drum. To provide an apparatus.
[0004]
[Means for Solving the Problems]
In order to solve the above-described problems, the configuration of the present invention is such that a guide cylinder having a rectangular inner section made of a nonmagnetic material is disposed inside a brake drum coupled to a rotating shaft, and an outer cylinder portion of the guide cylinder A large number of ferromagnetic plates are coupled at equal intervals in the circumferential direction, and each of the ferromagnetic plates is supported on the outer peripheral surface of at least one magnet support cylinder that is rotatably or axially supported in the inner space of the guide cylinder. In the eddy current moderation device, wherein the magnet is coupled so that the polarity with respect to the ferromagnetic plate is alternately different in the circumferential direction, the plate thickness of the portion from the central portion of the ferromagnetic plate to the inner surface facing the magnet The front surface of the ferromagnetic plate is inclined from the central portion of the plate thickness to the outer surface facing the brake drum toward the rear in the rotational direction of the brake drum, and the rear surface of the ferromagnetic plate is inclined from the central portion of the plate thickness. the portion extending outside surface facing the brake drum braking de The outer surface area of the ferromagnetic plate is made narrower than the inner surface area so that the outer surface of the ferromagnetic plate is in the center of the thickness of the ferromagnetic plate. It is characterized by the provision of a strip .
[0005]
DETAILED DESCRIPTION OF THE INVENTION
If the specifications or dimensions of the eddy current reduction device are the same, the braking force increases as the number of revolutions of the braking drum increases and the inner diameter of the braking drum increases. However, especially in the case of medium-sized cargo vehicles, if an eddy current reduction device is provided at the rear of the transmission, the inner diameter of the brake drum is limited, and if there are few opportunities to travel on the highway, the rotation speed of the brake drum is also limited. The It is desired to generate a larger braking force during normal traveling of the medium-sized cargo vehicle, that is, in the middle speed rotation region of the braking drum.
[0006]
In the present invention, since the distortion of the magnetic circuit at the time of braking is small in the middle speed rotation region of the braking drum, the magnetic flux reaching the braking drum from the magnet is concentrated at the central portion of the ferromagnetic plate. the shape of the cross-sectional side view of the magnetic plate to resemble a hexagonal, even without increasing the ferromagnetic plate, the effect narrowing the magnetic flux to the brake drum is exerted to reduce the machining of the front ferromagnetic plate casting .
[0007]
【Example】
FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention, and FIG. 2 is a side sectional view thereof. The eddy current reduction device according to the present invention includes, for example, a brake drum 7 made of a conductor coupled to an output rotation shaft 1 of a vehicle transmission, and a guide cylinder 10 made of a nonmagnetic material disposed inside the brake drum 7. , And a movable magnet support cylinder 14 housed in an inner space having a rectangular cross section of the guide cylinder 10. The brake drum 7 has the flange portion 5a of the boss 5 and the end wall portion of the brake drum 3 of the parking brake superimposed on the mounting flange 2 that is spline-fitted to the rotary shaft 1, and a plurality of bolts 4 and nuts. It is concluded. The base end of the brake drum 7 having the cooling fins 8 is coupled to a large number of spokes 6 extending radially from the boss 5.
[0008]
The guide cylinder 10 having a cross-sectional box shape is configured, for example, by connecting an end wall 11 made of an annular plate to a cylindrical body having a C-shaped cross section. The guide tube 10 is fixed to a gear box of a transmission, for example, by appropriate means. The outer cylinder portion 10a of the guide cylinder 10 is coupled by embedding a rectangular ferromagnetic plate (pole piece) 15 in a large number of openings 25 provided at equal intervals in the circumferential direction. Preferably, the ferromagnetic plate 15 is cast when the guide tube 10 is formed. Strictly speaking, from the viewpoint of strength, the guide tube 10 need only be a non-magnetic material for the outer tube portion 10a to which the ferromagnetic plate 15 is coupled.
[0009]
The magnet support cylinder 14 made of a magnetic material is supported by the inner cylinder portion 10b so that it can rotate forward and backward by a sliding bearing or roller bearing 12 in the inner space of the guide cylinder 10. The arm 16 extending in the axial direction from the magnet support cylinder 14 is connected to the rod of the fluid pressure actuator 20 through an arc-shaped slit 18 a provided on the left end wall of the guide cylinder 10. The magnet support cylinder 14 is coupled to the outer peripheral surface of the magnets 24 facing the ferromagnetic plates 15 so that the polarities with respect to the ferromagnetic plates 15 are alternately different in the circumferential direction. The actuator 20 coupled to the left end wall of the guide tube 10 is formed by fitting a piston 17 into the cylinder 18, and a rod protruding outward from the piston 17 is connected to the arm 16.
[0010]
In the present invention, the magnetic flux density from the magnet 24 toward the braking drum 7 (and vice versa) is similar to that of a conventional rectangular parallelepiped so that the magnetic flux density is maximized at the central portion of the ferromagnetic plate 15 (the central portion in the rotational direction of the braking drum 7). Unlike the above, the area of the outer surface 50 a of the ferromagnetic plate 15 facing the inner peripheral surface of the brake drum 7 is configured to be smaller than the area of the inner surface 50 b facing the magnet 24. Both side surfaces 50c of the ferromagnetic plate 15 are formed in a plane parallel to each other and perpendicular to the rotation axis (rotation axis of the brake drum 7).
[0011]
As shown in FIG. 4 , the ferromagnetic plate 15 includes an outer surface 50a having a small area facing the inner peripheral surface of the brake drum 7, an inner surface 50b having a large area covering the outer surface of the magnet 24, a front surface 15a, a rear surface 15b, Both side surfaces 50c parallel to each other are provided. The front surface 15a is inclined rearward in the rotational direction (arrow y) of the braking drum 7 from the middle between the inner surface 50b and the outer surface 50a toward the outer surface 50a. Similarly, the rear surface 15b is inclined forward in the rotational direction of the brake drum 7 from the middle between the inner surface 50b and the outer surface 50a toward the outer surface 50a.
[0012]
The ferromagnetic plate 15 is integrally formed with a retaining protrusion 15 c surrounding the entire periphery in advance, and is cast into the outer tube portion 10 a of the guide tube 10. The retaining protrusion 15c may use a parting line generated when the ferromagnetic plate 15 is manufactured by forging. After the casting of the guide tube 10, the outer peripheral surface and the inner peripheral surface of the outer tube portion 10a of the guide tube 10 are finished into a cylindrical surface by machining. As illustrated in FIG. 4, the retaining protrusion 15 c may be configured to extend in the circumferential direction without being inclined by the side surface 50 c of the ferromagnetic plate 15.
[0013]
In the embodiment shown in FIG. 5 , the portion of the outer tube portion 10a of the guide tube 10 that faces the brake drum 7 is made of a thin stainless steel plate. The ferromagnetic plate 15 is fitted into an opening 25 provided in the outer cylinder portion 10a made of a thin stainless steel plate, and is joined by welding or the like. Preferably, a groove-shaped reinforcing rib 31 extending in the axial direction is formed on the outer cylinder portion 10a. The reinforcing rib 31 may protrude outward from the outer cylinder portion 10a.
[0014]
In this embodiment, the ferromagnetic plate 15 is coupled to the inner surface 50b coincides with the inner peripheral surface of the outer cylindrical portion 10a, matching the outer surface 50a of the plate member 15 and the outer peripheral surface of the outer tubular portion 10a You may combine. Further, as shown in FIG. 5, the ferromagnetic plate 15 may be configured such that an intermediate portion between the outer surface 50a and the inner surface 50b is fitted into the opening 25 of the outer cylinder portion 10a and joined by welding.
[0015]
In the above embodiment, when not braked, as shown in FIG. 2, the two magnets 24 arranged in the circumferential direction of the magnet support cylinder 14 are opposite in polarity to the common ferromagnetic plate 15 as opposed to each other. ing. At this time, the two magnets 24 form a short-circuit magnetic circuit w between each ferromagnetic plate 15 and the magnet support cylinder 14, and do not exert a magnetic field on the brake drum 7. At the time of braking, as shown in FIG. 3, the two magnets 24 arranged in the circumferential direction have the same polarity facing each ferromagnetic plate 15, and exert a magnetic field on the braking drum 7 through the ferromagnetic plate 15. At this time, each magnet 24 forms a magnetic circuit z between the brake drum 7 and the magnet support cylinder 14. When the rotating brake drum 7 crosses the magnetic field, an eddy current flows through the brake drum 7 and the brake drum 7 receives a braking torque.
[0016]
As described above, in the present invention, the ferromagnetic plate 15 coupled to the outer tube portion 10a of the guide tube 10 has a side cross-sectional shape similar to a hexagon, and the area of the outer surface 50a is made larger than the area of the inner surface 50b. Since the magnetic flux reaching the brake drum 7 from the magnet 24 is narrowed, a strong magnetic field is applied to the brake drum 7. Therefore, the eddy current flowing through the braking drum 7 is increased and the braking force is increased.
[0017]
In the present invention, as shown in FIGS. 1 to 3, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside a brake drum 7 coupled to the rotary shaft 1. A large number of ferromagnetic plates 15 are arranged at equal intervals in the circumferential direction on the outer cylinder part 10a of the outer cylinder, and the outer peripheral surface of the magnet support cylinder 14 made of a magnetic body arranged in the inner space of the guide cylinder 10 so as to be able to rotate forward and backward. In addition, two magnets 24 are coupled to each ferromagnetic plate 15 so as to be opposed to each other and the polarity with respect to the ferromagnetic plate 15 is different every two in the circumferential direction. The magnet support cylinder 14 is switched by forward / reverse rotation by the fluid pressure actuator 20 between a non-braking position that opposes each other and a braking position in which the magnet 24 having the same polarity faces the entire ferromagnetic plate 15. The eddy current reducer is not limited to other types of eddy current reducers. It can be applied.
[0018]
In the embodiment shown in FIGS. 6 and 7, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside the brake drum 7 coupled to the rotary shaft 1. A large number of ferromagnetic plates 15 are arranged in the cylindrical portion 10a at equal intervals in the circumferential direction, and on the outer peripheral surface of the magnet support cylinder 14 made of a magnetic material disposed in the inner space of the guide cylinder 10 so as to be able to rotate forward and backward, The magnets 24 are coupled so that the polarities facing the respective ferromagnetic plates 15 are alternately different in the circumferential direction, and the two magnets 24 adjacent in the circumferential direction partially face each ferromagnetic plate 15 (see FIG. 6 ) and the brake position (state shown in FIG. 7 ) in which one magnet 24 is entirely opposed to each ferromagnetic plate 15 (see FIG. 7 ), the magnet support cylinder 14 is fluid pressure actuator 20 (see FIG. 1). by so switched to forward or reverse rotation, as shown in FIG. 4, the front 15 of the ferromagnetic plate 15 The tilted to the rotation direction rear side of the brake drum 7, by tilting the surface 15b after the plate member 15 in the rotational direction in front of the brake drum 7, the area of the outer surface 50a is smaller than the area of the inner surface 50b.
[0019]
In the embodiment shown in FIG. 8, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside the brake drum 7 coupled to the rotary shaft 1. A large number of ferromagnetic plates 15 are arranged at equal intervals in the circumferential direction 10a, and on the outer surfaces of the movable magnet support cylinder 14 and the stationary magnet support cylinder 14A made of a magnetic material housed in the inner space of the guide cylinder 10, The magnets 24 and 24A are coupled so as to face the ferromagnetic plate 15 and have different polarities with respect to the ferromagnetic plate 15 alternately in the circumferential direction, and the magnets 24 and 24A having different polarities face the respective ferromagnetic plates 15 entirely. Movable magnet support between the non-braking position (state shown in FIG. 8 ) and the braking position (same as the state shown in FIG. 7 ) in which the magnets 24, 24A having the same polarity are opposed to the respective ferromagnetic plates 15 . The cylinder 14 is moved by a fluid pressure actuator 20 and a half arrangement pitch of magnets 24 is obtained. Only to be switched to forward or reverse rotation, as shown in FIG. 4, the front surface of the ferromagnetic plate 15 is inclined to the rotation direction rear side of the brake drum 7, the rotational direction of the plane braking drum 7 after the ferromagnetic plate 15 The area of the outer surface 50a is made smaller than the area of the inner surface 50b by inclining forward.
[0020]
In the embodiment shown in FIG. 9, a guide cylinder 10 made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside the brake drum 7 coupled to the rotary shaft 1. A large number of ferromagnetic plates 15 are arranged at equal intervals in the circumferential direction 10a, and each ferromagnetic plate 15 is provided on the outer surface of a magnet support tube 14 made of a magnetic material supported in the inner space of the guide tube 10 so as to be movable in the axial direction. The magnets 24 are coupled so that the polarities thereof are alternately different in the circumferential direction, the magnet support cylinder 14 protrudes into the brake drum 7, and each of the magnets 24 faces the ferromagnetic plate 15 as shown in the illustrated braking position (see FIG. 7 ) and the non-braking position at which the magnet support cylinder 14 is retracted from the braking drum 7 in the axial direction and the magnets 24 do not face the ferromagnetic plate 15, the fluid pressure actuator 20 and to switch back and forth movement in the axial direction by, FIG. As shown in the front surface of the ferromagnetic plate 15 is inclined to the rotation direction rear side of the brake drum 7, by tilting the rear surface of the ferromagnetic plate 15 in the rotational direction in front of the brake drum 7, the area of the outer surface 50a inner surface 50b Narrower than the area.
[0021]
【The invention's effect】
In the present invention, as described above, a guide cylinder having an inner space with a rectangular cross section made of a non-magnetic material is disposed inside a brake drum coupled to a rotating shaft, and the outer cylinder of the guide cylinder is equidistant in the circumferential direction. A large number of ferromagnetic plates are coupled to each other, and the outer peripheral surface of at least one magnet support cylinder supported in the inner space of the guide cylinder so as to be rotatable or axially movable is opposed to each ferromagnetic plate and In the eddy current reduction device formed by coupling magnets so that the polarities with respect to the ferromagnetic plate are alternately different in the circumferential direction, the plate thickness of the portion extending from the central portion of the ferromagnetic plate to the inner surface facing the magnet is made uniform, The portion of the front surface of the ferromagnetic plate that extends from the central portion of the plate thickness to the outer surface facing the brake drum is inclined rearward in the rotation direction of the brake drum, and the rear surface of the ferromagnetic plate is opposed to the brake drum from the central portion of the plate thickness. The part that reaches the outer surface is in front of the braking drum in the rotational direction. Is inclined, thereby smaller than the area of the area of the inner surface of the outer surface of the ferromagnetic plate, is provided with the retaining projection surrounding the ferromagnetic plate in the center of the plate thickness of the ferromagnetic plate, The magnetic flux reaching the braking drum from the magnet is narrowed by the ferromagnetic plate, the eddy current flowing through the braking drum is increased, and the braking force is increased.
[Brief description of the drawings]
FIG. 1 is a front sectional view of an eddy current reduction device to which the present invention is applied.
FIG. 2 is a side cross-sectional view of the eddy current reduction device when not braked.
FIG. 3 is a side sectional view of the eddy current reduction device during braking.
FIG. 4 is a side view of another ferromagnetic plate.
FIG. 5 is a perspective view showing a coupling structure of a ferromagnetic plate to an outer tube portion of a guide tube made of a thin stainless steel plate in a second eddy current reduction device to which the present invention is applied.
FIG. 6 is a side cross-sectional view of the third eddy current reduction device to which the present invention is applied during non-braking.
FIG. 7 is a side sectional view of the eddy current reduction device during braking.
FIG. 8 is a front cross-sectional view of the fourth eddy current reduction device to which the present invention is applied during non- braking.
FIG. 9 is a front sectional view at the time of braking of the fifth eddy current reduction device to which the present invention is applied;
[Explanation of symbols]
3: Brake drum 6: Spoke 7: Brake drum 8: Cooling fin 10: Guide tube 10a: Outer tube portion 10b: Inner tube portion 14: Magnet support tube 14A: Magnet support tube 15: Ferromagnetic plate 15a: Front surface 15b: Rear surface 15c: retaining protrusion 20: actuator 24: magnet 24A: magnet 25: opening 50a: outer surface 50b: inner surface 50c: side surface

Claims (1)

A guide cylinder having a rectangular inner section made of a non-magnetic material is disposed inside the brake drum coupled to the rotating shaft, and a large number of ferromagnetic plates are coupled to the outer cylinder of the guide cylinder at equal intervals in the circumferential direction. The outer peripheral surface of at least one magnet support cylinder supported in the inner space of the guide cylinder so as to be rotatable or axially movable is opposed to each ferromagnetic plate and has a polarity in the circumferential direction. In the eddy current reduction device, in which the magnets are alternately coupled to each other, the thickness of the portion from the central portion of the ferromagnetic plate to the inner surface facing the magnet is made uniform, and the thickness of the front surface of the ferromagnetic plate is uniform. The portion from the central portion of the ferromagnetic plate to the outer surface facing the braking drum is inclined rearward in the rotational direction of the braking drum, and the portion of the rear surface of the ferromagnetic plate from the central portion of the plate thickness to the outer surface facing the braking drum is Tilt forward in the direction of rotation. Wherein the area of the outer surface of the ferromagnetic plate is smaller than the area of the inner surface, the eddy current deceleration, characterized in that a retaining projection surrounding the ferromagnetic plate in the center of the plate thickness of the ferromagnetic plate apparatus.

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