JP2001286123A - Eddycurrent brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a pressure on a contact surface, which is imposed to an external- peripheral surface of an internal cylinder of a guide cylinder, of a bearing bush pressed into an internal-peripheral surface of a magnet-support cylinder as well as to reduce the thermal load around the neighborhood of the contact surface. SOLUTION: An eddycurrent brake comprises a brake drum 7 connected to a rotating shaft, the guide cylinder 10 that is in the brake drum 7, mounted to a non-rotating portion of a chassis and the like and comprises a non-magnetic material having an internal space of a cross-sectional rectangular shape, at least one or more movable magnet-support cylinders 14 housed in the guide cylinder 10, a number of magnets 24 connected to the external-peripheral surface of the magnet-support cylinder 14 at regular intervals and a number of ferromagnetic materials 15 molded in a position facing a magnet 24 of the guide cylinder 10. A brake force is generated at the brake drum 7 by an eddycurrent based on a magnetic filed that arises from the magnet 24. While a resin dry bush 26 is connected to the internal-peripheral surface of the movable magnet-support cylinder 14, a steel cylinder section 33 having a groove 39 or a hollow 39a is externally connected to a ring-shaped groove 32 of the external- peripheral surface of the internal cylinder 10b of the guide cylinder 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current reduction device for assisting a friction brake of a vehicle or the like, and more particularly to an eddy current reduction device for switching between non-braking and braking by forward and reverse rotation of a magnet support cylinder. .

[0002]

2. Description of the Related Art In an eddy current reduction device in which a rotatable magnet support tube is accommodated in an inner space of a guide tube, a sintered metal tube such as copper is provided on an inner peripheral surface (axial hole) of the magnet support tube. Fluorine resin (PTF
E.) and a drive slush (bearing) impregnated with lead, and then externally inserted into the alumite-treated inner cylinder (shaft) of the aluminum guide cylinder to make the magnet support cylinder easier to rotate. are doing. The magnet support cylinder is connected to a rod of a fluid pressure actuator and is rotated forward and reverse between a braking position and a non-braking position.

[0003] Drive Tash uses a material mainly composed of fluorine resin such as Teflon (registered trademark).
When the contact pressure is low and high, the coefficient of friction increases,
The magnet support cylinder sometimes malfunctioned. That is,
When the contact pressure is low, the friction coefficient of a fluororesin-based drive shoe increases, and when the friction coefficient is large in a minute range of the contact surface, the temperature of the contact surface also increases. Further, when the ambient temperature is further increased due to the influence of heat due to the eddy current from the braking drum at the time of braking, the friction coefficient of the contact surface increases, which hinders the smooth operation of the magnet support cylinder.

According to the results of experiments on the fixing of the magnet support cylinder, when the inner cylinder portion made of aluminum or the like thermally expands at a high temperature during braking, the gap with the drive hash becomes narrower, and the locally worn portion becomes plastic. It is extruded in the circumferential direction through a flow (softening and melting) and is pushed into a narrow gap. When the rotational speed of the braking drum decreases, solidification of the plastic flow starts, and the friction coefficient becomes abnormally large. When the plastic flow remains solidified, the magnet support tube is fixed. What is important here is that the drive mesh, which is made by impregnating a sintered metal cylinder such as copper with fluorine resin (PTFE) and lead,
The fluorine resin functions as an elastic body and exhibits elastic friction characteristics. However, in a friction region where the contact surface pressure is high, it is considered that the frictional characteristics shift to the plastic friction characteristics of the sintered metal as the base.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to press-fit the inner peripheral surface of the magnet support cylinder with respect to the outer peripheral surface of the inner cylinder portion of the guide cylinder in consideration of the friction characteristics of the drive bush. While increasing the contact pressure of the drive
An object of the present invention is to provide an eddy current reduction device configured to reduce a heat load near a contact surface.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a construction of the present invention comprises a braking drum connected to a rotating shaft and a non-rotating part such as a vehicle body inside the braking drum. A guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section, at least one movable magnet support tube housed in the inner space of the guide tube, and circumferentially equidistantly arranged on the outer peripheral surface of the magnet support tube A large number of magnets coupled to the, and a large number of ferromagnetic materials are disposed at positions facing the magnet in the outer cylinder portion of the guide cylinder,
In an eddy current reduction device that generates a braking force on the braking drum by an eddy current based on a magnetic field from the magnet, a resin-based drive shoe is coupled to an inner peripheral surface of the movable magnet support cylinder, and A large number of steel plates supporting the drive shoe are connected to the outer peripheral surface of the inner cylindrical portion at equal intervals in the circumferential direction.

Further, according to the present invention, there is provided a brake drum connected to a rotating shaft, and a non-magnetic material having an inner space with a rectangular cross section which is attached to a non-rotating portion such as a vehicle body inside the brake drum. A guide tube, at least one movable magnet support tube housed in the inner space of the guide tube, a number of magnets connected to the outer peripheral surface of the magnet support tube at equal intervals in the circumferential direction, In the eddy current reduction device, a large number of ferromagnetic materials are provided at positions facing the magnet in the outer cylinder portion, and an eddy current based on a magnetic field from the magnet generates a braking force on the braking drum. While a resin-based drive shoe is connected to the inner peripheral surface of the magnet support cylinder, a steel cylinder is cast or externally fitted to the outer peripheral surface of the inner cylinder portion of the guide cylinder, and the outer peripheral surface of the steel cylinder is connected. Characterized in that a groove or a depression is provided in the groove.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a movable magnet support cylinder is rotatably supported via a resin-based drive bush on an inner cylinder part of a guide cylinder having a rectangular hollow inner part made of aluminum. . If the contact pressure is not high to some extent, the friction coefficient of the resin-based drive is high. When the temperature of the local frictional part becomes high (250 ° C.), the friction coefficient rapidly increases, and the magnet support cylinder It is difficult to switch between braking and non-braking by the forward and reverse rotation of. In particular, when the surface of the guide cylinder is subjected to alumite treatment, the heat insulating effect is enhanced, and it is difficult to suppress a rise in temperature.

Therefore, in the present invention, a steel cylinder is cast or pressed into the outer peripheral surface of the inner cylinder portion of the guide cylinder that supports the magnet support cylinder without performing alumite treatment on the surface of the guide cylinder made of aluminum casting. . Grooves or depressions are provided on the outer peripheral surface of the steel cylindrical body to increase the contact surface pressure (friction surface pressure) with the resin-based drive shoe pressed into the inner peripheral surface of the magnet support cylinder. The grooves and depressions may be of any suitable shape divided in the circumferential direction, and are formed when the steel cylinder is pressed or cast into a guide cylinder. Moreover, after casting, a hollow or a groove may be formed by machining.

[0010]

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 of the same. The eddy current reduction device according to the present invention includes, for example, a braking drum 7 made of a conductor coupled to the output rotation shaft 1 of a vehicle transmission, a guide cylinder 10 made of a non-magnetic material disposed inside the braking drum 7, Guide tube 1
It has a movable magnet support tube 14 housed in an inner space portion 37 having a rectangular cross section of 0 and an immovable magnet support tube 14A fixed by a detent pin 13. The brake drum 7 has the flange portion 5a of the boss 5 and the end wall of the brake drum 3 of the parking brake together with the mounting flange 2 spline-fitted to the rotating shaft 1.
And fastened by a plurality of bolts 4 and nuts. Numerous spokes 6 extending radially from boss 5
, The base end of the braking drum 7 provided with the cooling fin 8 is connected.

The guide cylinder 10 having a rectangular cross section is constituted by connecting an end wall 11 formed of an annular plate to a cylinder having a C-shaped cross section, for example. The guide tube 10 is fixed by a suitable means to, for example, a gearbox of a vehicle transmission. Outer tube part 10 of guide tube 10
A rectangular ferromagnetic material (pole piece) 15 having a retaining ridge 15c on the periphery is coupled to a number of openings 25 provided at equal intervals in the circumferential direction in FIG. Preferably, the ferromagnetic material 15 is cast when the guide tube 10 is formed. Also, the magnetic material may be joined by welding instead of casting, or a composite material of ferromagnetic material and non-magnetic material (may be a weak magnetic material) (stainless steel, etc.)
May be.

The magnet support cylinder 14 made of a magnetic material is supported by the drive cylinder 26 on the inner cylinder 37 of the guide cylinder 10 so as to be rotatable forward and backward. Magnet support cylinder 1
Reference numeral 4 denotes a magnet 24 coupled to the ferromagnetic material 15 on the outer peripheral surface so that the polarity of the ferromagnetic material 15 is alternately different in the circumferential direction. The magnet support tube 14A made of a magnetic material is fixed to the inner tube portion 10b at the inner space 37 of the guide tube 10 and, like the magnet support tube 14, the magnet support tube 14 is attached to the ferromagnetic material 15 on the outer peripheral surface. The opposing magnets 24 are coupled such that the polarity with respect to the ferromagnetic material 15 is alternately different in the circumferential direction. Although not shown, a protruding wall portion that protrudes in the axial direction from the left end wall of the magnet support tube 14 is formed in the inner space 37 from a piston fitted to the cylinder 18 of the actuator 20 integrated with the left end wall of the guide tube 10. Connected to the projecting rod.

As shown in FIG. 2, the magnetic flux density from the magnet 24 to the braking drum 7 (and vice versa) is equal to the magnetic flux density of the ferromagnetic material 15.
The area of the outer surface of the ferromagnetic material 15 facing the inner peripheral surface of the braking drum 7 faces the magnet 24 so that the area becomes maximum in the central portion (the central portion in the rotation direction of the braking drum 7 (arrow y)). It may be configured to be smaller than the area of the inner surface. In this case, the front surface 15a of the ferromagnetic material 15 is inclined rearward in the rotation direction (arrow y) of the braking drum 7 from the middle toward the outer surface. Similarly, the rear surface 15b of the ferromagnetic material 15 is inclined forward in the rotation direction of the braking drum 7 from the middle toward the outer surface.

As shown in FIG. 1, a groove 28 and a groove 29 extending in the circumferential direction are provided at both ends of the drive hash 26 in order to store abrasion powder generated by wear of the drive hash 26. Each of the grooves 28 and 29 may be an annular groove, but the magnet support tube 14 is
4, the grooves 28 and 29 are provided on the outer peripheral surface of the inner cylinder portion 10b in the upper half portion of the magnet support tube 14, and the magnets are provided in the lower half portion of the magnet support tube 14 in the upper half portion. Preferably, grooves 28 and 29 are provided on the inner peripheral surface of the support cylinder 14. Note that the annular groove may not be provided.

As shown in FIG. 3, according to the present invention, an annular groove 32 is provided on a portion (width s) where the movable magnet support tube 14 is supported, that is, on the outer peripheral surface of the inner tube portion 10b of the guide tube 10. A large number of circumferentially divided steel plates 33a are connected to the inside of the annular groove 32 to define a groove 39, and the outer surface of the steel plate 33a supports the resin-based drive shoe 26 pressed into the magnet support cylinder 14. It was made. The groove 32 is formed integrally when the guide cylinder 10 is cast, and the surface of the groove 32 may be left as a casting surface without anodizing. As a result, the supporting area of the guide cylinder 10 for supporting the resin-based drive hash 26 is reduced, and the supporting area or the friction area is reduced accordingly, so that the contact surface pressure is increased and the friction of the resin-based drive hash 26 against the steel plate 33a is increased. The coefficient becomes smaller, and the switching operation between braking and non-braking by the smooth forward and reverse rotation of the magnet support cylinder 14 can be obtained. It is preferable that a large number of steel plates 33a be integrally cast when the guide tube 10 is cast from aluminum. At this time, the axial lengths of the steel plate 33a and the groove 39 may be arranged to the portion supporting the immovable magnet support tube 14A, that is, over the entire width.

A steel plate which is not divided in the circumferential direction, that is, a steel cylindrical body 33 is connected to the inner cylindrical portion 10 of the guide cylinder 10 made of aluminum.
In the case of external fitting to b, it is preferable to provide a number of axial grooves 39 on the outer peripheral surface of the steel cylindrical body 33 at equal circumferential intervals.
As shown in FIG. 4, the groove 39 provided in the steel cylinder 33 is not parallel to the rotation axis of the braking drum 7, and the groove 39 can be provided diagonally.

In the embodiment shown in FIG. 5, a steel cylinder 33 is provided with recesses 3 such as rectangular, triangular and elliptical sections at equal intervals in the circumferential direction.
9a is provided or the one obtained by punching the opening is
This is pressed into the annular groove 32 of FIG.

In the embodiment shown in FIG. 6, an annular groove 34 extending in the circumferential direction is provided on the outer peripheral surface of the steel cylinder 33, and the steel cylinder 33 is provided on the outer peripheral surface of the inner cylinder portion 10b. Groove 32
(Note that a plurality of annular grooves 34 may be provided). Boundary line 31 in the circumferential direction that divides inner cylinder portion 10b into two
A movable magnet support tube 14 is supported on the left side, and an immovable magnet support tube 14A is supported on the right side.

When the brake is not applied, as shown in FIG. 1, two magnets 24, 24A arranged in the axial direction of the magnet support cylinders 14, 14A.
Are opposite to each other in polarity opposite to the common ferromagnetic material 15. At this time, the two magnets 24, 24A form a short-circuit magnetic circuit w between each ferromagnetic body 15 and the magnet support cylinder 14, 14A, and do not apply a magnetic field to the braking drum 7. At the time of braking, as shown in FIG.
4, 24A (the magnet 24A is shown in FIG. 1) is a ferromagnetic material 15
, And the magnetic field is applied to the braking drum 7 via the ferromagnetic material 15. At this time, each magnet 24, 24A
Forms a magnetic circuit z between the brake drum 7 and the magnet support cylinders 14 and 14A. 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.

As shown in FIG. 10, in a drive mesh 26 in which a sintered metal such as copper is impregnated with fluorine resin (PTFE) and lead, the fluorine resin acts as an elastic body in a friction region where the contact surface pressure is low. In a friction region where the friction coefficient is large and the contact surface pressure is high, the friction coefficient shifts to the plastic friction characteristic of the base sintered metal cylinder, and the friction coefficient is small and shows a substantially constant value. In the present invention, the inner cylinder portion 10b of the guide cylinder 10
By providing a wide groove 39 on the outer peripheral surface of the, the contact area is reduced, so that the contact surface pressure of the drive hash 26 against the inner cylindrical portion 10b is increased, the friction coefficient is reduced, and heat generation is suppressed. Groove or recess 39a
The heat load in the vicinity of the contact surface is reduced by the presence of, and the smooth operation of the magnet support tube 14 is guaranteed.

In the above-described embodiment, the eddy current reduction device of the type having a movable magnet support cylinder and an immovable magnet support cylinder and switching between braking and non-braking by the rotational differential between the two has been described. However, the present invention is not limited to this, and can be applied to an eddy current reduction device of a type in which switching between braking and non-braking is performed by forward and reverse rotation of a single magnet support cylinder.

In the embodiment shown in FIGS. 7 and 8, a single magnet support cylinder 14 is supported in the inner space of the guide cylinder 10 so as to be able to rotate forward and backward, and two magnets arranged in the circumferential direction of the magnet support cylinder 14 are arranged. 24 is a non-braking position partially facing the common ferromagnetic body 15;
One of the magnets 24 is switched to a braking position where the two magnets 24 entirely oppose the ferromagnetic material 15. In the eddy current reduction device of this type, the steel tubular body 33 or the steel plate 33a divided in the circumferential direction is, of course, arranged over the entire width of the inner tubular portion 10b. In this case, the axial grooves 39, the depressions or openings 39a, and the annular grooves 34 are preferably provided in a plurality of rows at intervals in the axial direction. Other configurations are the same as those shown in FIGS.

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 connected to the rotating shaft. A large number of ferromagnetic materials 15 are arranged at equal intervals in the circumferential direction in the cylindrical portion 10a, and the outer peripheral surface of a magnet support tube 14 made of a magnetic material arranged in the inner space of the guide cylinder 10 so as to be able to rotate forward and backward. Each ferromagnet 1
The magnets 24 are coupled so that two magnets 24 face each other and the polarity with respect to the ferromagnetic material 15 is different for every two magnets in the circumferential direction. The magnet support tube 14 is positioned between a non-braking position and a braking position in which two magnets 24 of the same polarity completely oppose each ferromagnetic material 15.
Are rotated by the actuator 20 in the forward and reverse directions. A resin drive shoe is connected to the inner peripheral surface of the magnet support tube 14. On the other hand, the inner cylinder portion 10b supporting the magnet support cylinder 14 is provided with one or a plurality of annular grooves 32, and a plurality of steel plates are joined to the annular groove 32 at equal intervals in the circumferential direction so as to be cut in the circumferential direction. 39 are formed. A steel tubular body 33 is externally fitted and supported in the annular groove 32, and a large number of grooves 39, depressions or openings 39 a are provided at equal circumferential intervals on the outer peripheral surface of the steel tubular body 33, or an annular groove 39 is provided. .

[0024]

As described above, the present invention relates to a brake drum connected to a rotating shaft and a non-rotating part which is attached to a non-rotating part such as a vehicle body inside the brake drum and has a rectangular hollow section. A guide tube made of a magnetic material, at least one movable magnet support tube housed in the inner space of the guide tube, a large number of magnets connected to the outer peripheral surface of the magnet support tube at equal intervals in the circumferential direction, In an eddy current reduction device, a large number of ferromagnetic materials are disposed at positions facing the magnet in the outer cylinder portion of the guide cylinder, and a braking force is generated on the braking drum by an eddy current based on a magnetic field from the magnet. A resin-type drive shoe is coupled to the inner peripheral surface of the movable magnet support cylinder, while a number of steel plates are coupled to the outer peripheral surface of the inner cylinder portion of the guide cylinder, or a steel cylinder is externally coupled to the movable cylinder. Since a groove or a depression was provided on the outer peripheral surface of the steel cylinder, the steel cylinder was Area of frictional contact with the system Doraibutsushiyu is narrowed, it is possible to much surface pressure of the friction surface is increased, lowering the friction coefficient of the friction surface. As a result, heat generation on the friction surface is suppressed, and a smooth switching operation between braking and non-braking by forward and reverse rotation of the magnet support cylinder can be obtained.

[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 when braking is not performed.

FIG. 2 is a side sectional view of the eddy current reduction device during braking.

FIG. 3 is a perspective view showing an inner cylinder portion of a guide cylinder of the eddy current reduction device.

FIG. 4 is a perspective view showing another embodiment of a steel cylindrical body fitted externally to an inner cylindrical portion of a guide cylinder of the eddy current reduction device.

FIG. 5 is a perspective view showing another embodiment of the inner cylinder portion of the guide cylinder of the eddy current reduction device.

FIG. 6 is a perspective view showing another embodiment of the inner cylinder portion of the guide cylinder of the eddy current reduction device.

FIG. 7 is a front sectional view of another eddy current reduction device to which the present invention is applied.

FIG. 8 is a side sectional view of the eddy current reduction device when no braking is performed.

FIG. 9 is a side sectional view of another eddy current reduction device to which the present invention is applied, when no braking is performed.

FIG. 10 is a diagram illustrating friction characteristics of a rotation support portion of a magnet support cylinder of the eddy current reduction device.

[Explanation of symbols]

1: Rotary shaft 6: Spoke 7: Brake drum 10: Guide cylinder 10a: Outer cylinder 10b: Inner cylinder 14: Magnet support cylinder 14A: Magnet support cylinder 15: Ferromagnetic material 20: Actuator 24: Magnet 24A: Magnet 26 : Drive mesh 32: Annular groove 33: Steel cylinder 39: Groove 39a: Recess

Claims (4)

[Claims] 1. A brake drum connected to a rotating shaft, a guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section, which is attached to a non-rotating part such as a vehicle body inside the brake drum, At least one movable magnet support cylinder housed in the inner space of the guide cylinder, a number of magnets connected to the outer peripheral surface of the magnet support cylinder at equal circumferential intervals, and In an eddy current reduction device in which a large number of ferromagnetic materials are disposed at positions facing the magnet and an eddy current based on a magnetic field from the magnet generates a braking force on the braking drum, the movable magnet support cylinder An eddy current characterized in that a resin-based drive shoe is connected to the inner peripheral surface, and a number of steel plates supporting the drive push are connected to the outer peripheral surface of the inner cylindrical portion of the guide cylinder at equal circumferential intervals. Reduction gear. 2. A brake drum connected to a rotating shaft, a guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section, which is attached to a non-rotating portion such as a vehicle body inside the brake drum. At least one movable magnet support cylinder housed in the inner space of the guide cylinder, a number of magnets connected to the outer peripheral surface of the magnet support cylinder at equal circumferential intervals, and In an eddy current reduction device in which a large number of ferromagnetic materials are disposed at positions facing the magnet and an eddy current based on a magnetic field from the magnet generates a braking force on the braking drum, the movable magnet support cylinder While a resin-based drive shoe is coupled to the inner peripheral surface, a steel cylinder is cast or externally fitted to the outer peripheral surface of the inner cylinder portion of the guide cylinder, and a groove or a depression is formed in the outer peripheral surface of the steel cylinder. An eddy current reduction device characterized by being provided. 3. The eddy current reduction device according to claim 2, wherein a plurality of said grooves or depressions are provided in said steel cylinder at equal circumferential intervals. 4. The eddy current reduction device according to claim 2, wherein said groove is at least one annular groove extending in a circumferential direction of said steel cylinder.