JP3702794B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current type speed reducer attached to a large vehicle such as a bus or a truck as a braking assist device.
[0002]
[Prior art]
In recent years, for large vehicles such as buses and trucks, stable deceleration on long downhills, etc., reducing the number of times the foot brake is used, preventing abnormal lining wear and fading, and braking stop distance For the purpose of shortening the eddy current type speed reducer, in addition to a foot brake as a main brake and an exhaust brake as an auxiliary brake, an eddy current type speed reducer has been attached. There are two types of eddy current type reduction gears that use an electromagnet as a magnet and one that uses a permanent magnet. Recently, there are many that use a permanent magnet that does not require energization during braking. Yes.
[0003]
As an eddy current type speed reducer using this permanent magnet, for example, the one proposed by the present applicant in Japanese Patent Application No. 1-2298948 is shown in FIG. 7, and as shown in FIG. A group of permanent magnets 3 which are supported in opposition to the rotor 1 and are evenly arranged on the support ring 2 of the ferromagnetic material so that the directions of the magnetic poles are opposite to each other along the circumferential direction of the rotor 1; Between the permanent magnet 3 group and the rotor 1, the same number of ferromagnetic magnet switch plates 4 as the permanent magnets 3 are interposed between the switch plates 4 of the switch plate 4 group. A nonmagnetic support member 5 is provided, and a predetermined gap is maintained between the outer peripheral surface of the permanent magnet 3 and the inner peripheral surface of the switch plate 4. In FIG. 7, 1a is a cylindrical portion of the rotor 1, 1b is a cooling fin of the rotor 1, 6 is a drive portion that reciprocates the support ring 2 by a predetermined angle, and 7 is an inner peripheral surface side and both side wall sides of the support ring 2. The bearings are respectively interposed between the support body 5 and the support ring 2 so as to rotatably support the support ring 2.
[0004]
In the eddy current type speed reducer proposed in JP-A-1-298948, when the support ring 2 is rotated so that the permanent magnet 3 overlaps with the switch plate 4 as shown in FIG. 2, the adjacent permanent magnet 3 and the adjacent switch plate 4, and the cylindrical portion 1 a of the rotor 1, a magnetic circuit is formed as shown by an arrow, and a so-called braking ON state is established. The magnetic flux from the permanent magnet 3 acts to generate eddy current, and braking torque is generated.
[0005]
Therefore, a high braking force can be obtained by passing a large amount of magnetic flux through the magnetic circuit including the rotor 1 during braking. Therefore, increasing the magnetic capacity of circuit components such as the support ring 2 and the switch plate 4 during braking and reducing the magnetic resistance on the magnetic circuit during braking increases braking efficiency and is an expensive permanent magnet. Can be saved, leading to cost reduction.
[0006]
Further, when the support ring 2 is turned from the above-described brake-on position, and as shown in FIG. 8 (b), one permanent magnet 3 straddles the adjacent switch plate 4 and is in a state of being overlapped half by half, the support is provided. A short-circuit magnetic circuit is formed by the ring 2, the adjacent permanent magnet 3 and one switch plate 4 as shown by an arrow, and a so-called braking OFF state is established.
[0007]
In this state, it is ideal that no eddy current flows in the cylindrical portion 1a and no braking torque is generated. However, since the switch plate 4 and the cylindrical portion 1a are close to each other, in reality, FIG. ), A part of the magnetic flux passing through the switch plate 4 enters the cylindrical portion 1a of the rotor 1 and generates a drag torque on the cylindrical portion 1a. cause.
[0008]
Therefore, in order to prevent the generation of this drag torque, conventionally, in order to suppress the intrusion of magnetic flux from the switch plate to the cylindrical portion of the rotor, the circumferential cross-sectional area of the switch plate is made sufficiently large, It was easy to pass the magnetic flux.
[0009]
[Problems to be solved by the invention]
However, as described above, the method of increasing the cross-sectional area in the circumferential direction of the switch plate inevitably increases the thickness of the switch plate, which increases the magnetic resistance of the magnetic circuit during braking, and increases the braking efficiency. A vicious circle that caused a decline in
[0010]
The present invention has been made in view of the above-described conventional problems, and suppresses the magnetic flux generated from the permanent magnet at the time of braking OFF without impairing the braking force at the time of braking ON, and from the switch plate to the cylinder of the rotor. An object of the present invention is to provide an eddy current type speed reducer capable of suppressing magnetic flux leaking to a portion and suppressing drag torque.
[0011]
[Means for Solving the Problems]
In order to achieve the above-described object, the eddy current type reduction device according to the present invention has a circumferential cross-sectional area A represented by the following mathematical formula 1 of the support ring in an eddy current type reduction device of a single row swirl type. κ = 0.08 to 0.12, or the support ring is divided into two in the radial direction, and the cross-sectional area of the support ring is large between adjacent permanent magnets during braking, and adjacent when not braking The configuration is such that the cross-sectional area of the support ring between the permanent magnets is reduced. And by doing in this way, without compromising the braking force at the time of braking ON, the magnetic flux generated from the permanent magnet is suppressed at the time of braking OFF, the magnetic flux leaking from the switch plate to the cylindrical portion of the rotor is suppressed, and the drag torque is reduced. It becomes possible to suppress.
[0012]
[Expression 1]
A = κ · (BHmax · W / ρ) / Br
However, BHmax: Maximum energy product (J / m ³ ) of the permanent magnet used
W: Permanent magnet mass per unit (kg)
ρ: Specific gravity of the permanent magnet used (kg / m ³ )
A: Cross-sectional area in the circumferential direction of the support ring (m ² )
Br: saturation magnetic flux density (T) of the support ring at a magnetic field strength of 5000 A / m
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 5 and FIG. 6 show the magnetic circuit at the time of braking and non-braking of the single row turning type eddy current type reduction gear. 5 and 6 are represented as a current circuit by regarding the magnetic flux flowing in the magnetic circuit as a current for easy understanding.
[0014]
At the time of braking shown in FIG. 8A, for example, the magnetic flux flowing out from the permanent magnet 3 on the left side of the paper is the gap between the permanent magnet 3 on the left side of the paper and the switch plate 4 → the switch plate 4 on the left side of the paper → the left side of the paper. The gap between the switch plate 4 and the rotor cylinder 1a → the gap between the rotor cylinder 1a and the switch plate 4 on the right side of the paper through the rotor cylinder 1a → the switch plate 4 on the right side of the paper → the switch plate 4 on the right side of the paper The gap between the permanent magnets 3 returns to the permanent magnet 3 on the left side of the drawing through the support ring 2.
[0015]
FIG. 5 shows the magnetic circuit at the time of braking replaced with a current circuit. In FIG. 5, the permanent magnet 3 is considered to correspond to a power source, and is represented by BH. The resistance of the circumferential section of the support ring 2 (cross section AA in FIG. 8A) is R _{y (A)} , the resistance of the gap between the permanent magnet 3 and the switch plate 4 is R _Gap1 , and the switch plate. _{RP (A)} is the resistance of the cross section 4 in the height direction (BB cross section in FIG. 8A ₎ , R _Gap2 is the resistance of the gap between the switch plate 4 and the rotor cylinder 1a, and the cylinder 1a of the rotor. The resistance of the circumferential cross section (CC cross section in FIG. 8A) is considered as R _D.
[0016]
In the current circuit shown in FIG. 5, when the total resistance during braking is R _ON , the magnitude of the current (magnetic flux) I _ON during braking can be expressed as I _ON ∝BH / R _ON . Here, since R _ON = (R _Gap1 + R _{P (A)} + R _Gap2 ) × 2 + R _D + R _{y (A)} , R _ON >> R _{y (A)} .
[0017]
On the other hand, at the time of non-braking shown in FIG. 8B, for example, the magnetic flux flowing out from the permanent magnet 3 on the left side of the page is a gap between the permanent magnet 3 on the left side of the page and the switch plate 4 at the center of the page. The gap between the switch plate 4 at the center of the paper surface and the permanent magnet 3 on the right side of the paper surface returns to the permanent magnet 3 on the left side of the paper surface through the support ring 2.
[0018]
Further, the drag torque at the time of non-braking shown in FIG. 8B flows out of, for example, the permanent magnet 3 on the left side of the paper, and the gap between the permanent magnet 3 on the left side of the paper and the switch plate 4 at the center of the paper → the switch at the center of the paper surface. Part of the magnetic flux that has passed through the plate 4 flows into the rotor cylinder 1a via the gap between the switch plate 4 at the center of the paper and the cylinder 1a of the rotor, and the gap between the cylinder 1a of the rotor and the switch plate 4 at the center of the paper. → Switch plate 4 in the center of the page → Gap between the switch plate 4 in the center of the page and the permanent magnet 3 on the right side of the page → Returns to the permanent magnet 3 on the left side of the page through the support ring 2.
[0019]
FIG. 6 shows the non-braking magnetic circuit replaced with a current circuit. In the current circuit shown in FIG. 6, the circumferential direction of the switch plate 4 (cross section DD in FIG. 8B). When the resistance is R _{P (t)} and the total resistance during non-braking is R _OFF , the magnitude of the current (magnetic flux) I _OFF during non-braking can be expressed as I _OFF ∝BH / R _OFF . Here, R _OFF = 2 · R _Gap1 + R ′ + R _{y (A)} , where 1 / R ′ = (1 / R _{P (t)} ) + 1 / (2 · R _{P (A)} + 2 · R _Gap2 + R _D ), R _OFF > R _{y (A)} .
[0020]
Further, the magnetic resistances R _Gap1 and R _Gap2 of the gap are the magnetic resistances R _{P (A)} , R _{P (t)} , R _D , R _{y (A )} And R _ON >> R _OFF , it can be seen that the influence of the support ring 2 is small during braking and large during non-braking. Accordingly, by reducing the circumferential cross-sectional area of the support ring 2, the flow of magnetic flux during non-braking, and hence the drag torque can be reduced.
[0021]
An eddy current reduction device according to a first aspect of the present invention is made on the basis of the above-described concept, and includes a rotor that is integrally attached to a rotating shaft, and is supported so as to face the rotor. A permanent magnet group that is evenly arranged on the support ring of the ferromagnetic material so that the directions of the magnetic poles are opposite to each other along the direction, and the same number of permanent magnets between the permanent magnet group and the rotor In an eddy current reduction device comprising a ferromagnetic switch plate group that is evenly interposed and a non-magnetic support member portion that is interposed between the switch plates of the switch plate group, The circumferential cross-sectional area A of the represented support ring is in the range of κ = 0.08 to 0.12.
[0022]
In the eddy current reduction device according to the first aspect of the present invention, the circumferential cross-sectional area A of the support ring represented by Equation 1 is in the range of κ = 0.08 to 0.12. In the single row swirl type eddy current type speed reducer, the braking torque and the drag torque were measured when the circumferential cross-sectional area A of the support ring obtained by Equation 1 was changed (when κ was changed). Based on the results.
[0023]
FIG. 1 shows the results of measurement of braking torque and drag torque when the cross-sectional area A in the circumferential direction of the support ring is changed (when κ is changed). FIG. 1 shows that κ exceeds 0.12. In this case, it can be seen that the braking torque is saturated. In addition, when κ is less than 0.08, it can be seen that although the rate of decrease in drag torque does not change much, the braking torque decreases greatly.
[0024]
From this result, the cross-sectional area A in the circumferential direction of the support ring obtained by Equation 1 in the single-row swirling type eddy current type reduction gear is set to a cross-sectional area such that κ is in the range of 0.08 to 0.12. In this case, for example, in the eddy current type speed reducer with the following specifications, the braking torque can ensure 90% or more of the maximum generated torque, and the drag torque at the time of braking OFF can be suppressed to 18 to 28% of the maximum. become able to.
[0025]
Single row swirl type eddy current type speed reducer specifications BHmax: 360 (kJ / m ³ )
W: 199 (g / 1 piece)
ρ: 7.5 × 10 ³ (kg / m ³ )
A when κ = 0.1: 586 (mm ² )
Br: 1.63 (T)
[0026]
In the eddy current reduction device according to the first aspect of the present invention, the magnetic flux density Br of the support ring is set to the saturation magnetic flux density at a magnetic field strength of 5000 A / m. This is because if the strength is different, the magnetic flux density Br is different, and therefore, when only the magnetic flux density Br is determined, the applicable support ring becomes ambiguous.
[0027]
An eddy current type speed reducer according to a second aspect of the present invention includes a rotor that is integrally attached to a rotating shaft, and is supported so as to face the rotor, and the directions of magnetic poles are opposite to each other along the circumferential direction of the rotor. A permanent magnet group arranged evenly on the support ring of the ferromagnetic material so as to be oriented, and the same number of ferromagnetic magnets interposed between the permanent magnet group and the rotor as many as the permanent magnets. In an eddy current type speed reducer comprising a switch plate group and a non-magnetic support portion interposed between the switch plates of the switch plate group, the support ring is divided into two in the radial direction and adjacent to each other during braking. The cross-sectional area of the support ring between the permanent magnets is large, and the cross-sectional area of the support ring between the adjacent permanent magnets is small during non-braking.
[0028]
In the eddy current type speed reducer according to the second aspect of the present invention, in a braking OFF state in which one permanent magnet is overlapped by half across the adjacent switch plates, the cross-sectional area of the support ring between the adjacent permanent magnets is small. Therefore, the magnetic flux generated from the permanent magnet is suppressed, the magnetic flux inevitably leaking to the cylindrical portion of the rotor can be reduced, and the drag torque is reduced.
[0029]
【Example】
Hereinafter, the eddy current type speed reducer of the present invention will be described based on the embodiments shown in FIGS. 2 to 4, the same reference numerals as those in FIGS. 7 and 8 denote the same or corresponding parts, and detailed description thereof is omitted.
FIG. 2 is a cross-sectional view showing a first embodiment of the eddy current type speed reducer according to the second aspect of the present invention in the direction of the rotation axis. FIG. FIG. 3 is an explanatory view showing a state, FIG. 3 is a sectional view showing a second embodiment of the eddy current type speed reducer according to the second aspect of the present invention in the rotational axis direction, and (a) is an explanatory view showing a state of braking OFF. FIG. 4 is an explanatory view showing a state of braking ON, FIG. 4 is a cross-sectional view showing a third embodiment of the eddy current type speed reducer according to the second aspect of the present invention, and FIG. The figure shown, (b) is a sectional view taken on line AA of (a), (c) is an arrow B view of (a) showing the state of braking OFF, (d) shows the state of braking ON (a) FIG.
[0030]
In the eddy current type speed reducer according to the first aspect of the present invention, for example, a permanent magnet having a density ρ of 7500 kg / m ³ and a mass W of 199 g per unit is set so that the maximum energy product BHmax is 360 kJ / m ^3. In the case of the single row swirl type eddy current speed reducer provided, the circumferential cross-sectional area A of the support ring using a material having a saturation magnetic flux density Br of, for example, 1.63 T when the magnetic field strength is 5000 A / m is 468. between 8 mm ² of 703.2Mm ^2, i.e., one in which κ in equation 1 is set in the range of 0.08 to 0.12.
[0031]
By setting the circumferential cross-sectional area A of the support ring in the above-described range, the magnetic force generated from the permanent magnet is suppressed at the time of braking OFF without impairing the braking force at the time of braking ON. Magnetic flux leaking to the cylindrical portion can be suppressed, and drag torque can be suppressed.
[0032]
2-4, instead of determining the circumferential cross-sectional area of the support ring within a certain range as in the eddy current type speed reducer according to the first aspect of the present invention described above, the support ring is arranged in the radial direction. The vortex according to the second aspect of the present invention, which is divided into two and is configured such that the cross-sectional area of the support ring between adjacent permanent magnets is large during braking and the cross-sectional area of the support ring between adjacent permanent magnets is small during non-braking. The specific Example of an electric current type reduction gear is shown.
[0033]
That is, the first embodiment shown in FIG. 2 faces the central portion in the circumferential direction of the switch plate 4 in the first support ring 11 fixed to the support body 5, which is located on the inner peripheral side of the two divided in the radial direction. It is the structure which provided the ditch | groove 11a which reaches the whole width direction in the position to carry out.
[0034]
In this way, the permanent magnet 3 that is evenly installed on, for example, the outer peripheral surface of the second support ring 12 located on the outer peripheral side of the two divided in the radial direction is opposed to the switch plate 4 as shown in FIG. In the braking ON state shown in (2), the circumferential cross-sectional area of the support ring is increased (substantially the same as the circumferential cross-sectional area of the conventional support ring 2), and the braking torque is not impaired.
[0035]
Then, the second support ring 12 is swung from the braking ON state shown in FIG. 2 (b) to the braking OFF state shown in FIG. 2 (a) in which one permanent magnet 3 overlaps the adjacent switch plates 4 and overlaps each other by half. If this is done, the circumferential cross-sectional area of the support ring is reduced by the amount of the concave groove 11a, the magnetic flux flowing through the short circuit magnetic circuit is reduced, and the magnetic flux inevitably leaking from the switch plate to the cylindrical portion of the rotor is reduced. The drag torque is reduced. 2 denotes a bearing interposed between the first support ring 11 and the second support ring 12.
[0036]
Further, the second embodiment shown in FIG. 3 replaces the first embodiment shown in FIG. 2 with the support body 5 having the same number of polygons as the number of permanent magnets 3 installed. The apex angle is arranged so as to face the substantially circumferential center of the switch plate 4, and the first support located on the outer peripheral surface of the support 5 is located on the inner peripheral side of the two divided in the radial direction. The body 13 is arranged with a predetermined interval between the adjacent first supports 13.
[0037]
The second embodiment shown in FIG. 3 also achieves the same operational effects as the first embodiment shown in FIG. Note that reference numeral 14 in FIG. 3 denotes a bearing interposed between the first support 13 and the second support ring 12.
[0038]
Further, in the third embodiment shown in FIG. 4, one side in the width direction of the first support ring 11 of the first embodiment shown in FIG. 2 (the left side in FIG. 4A) is arranged at the bottom of the groove 11a. The notch portion 11b is made to project the opposite portion of the second support ring 12, and the projecting portion 12a is made to face the notch portion 11b.
[0039]
The third embodiment shown in FIG. 4 also achieves the same operational effects as the first embodiment shown in FIG.
[0040]
【The invention's effect】
As described above, according to the eddy current reduction device of the present invention, the magnetic flux generated from the permanent magnet can be suppressed when the brake is OFF without damaging the braking force when the brake is ON. Therefore, the magnetic flux leaking from the switch plate to the cylindrical portion of the rotor inevitably decreases with the decrease of the magnetic flux generated from the permanent magnet at the time of braking OFF, and the drag torque can be suppressed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an eddy current type speed reducer according to the first aspect of the present invention, in which braking is performed when the cross-sectional area A in the circumferential direction of the support ring obtained by Equation 1 is changed (when κ is changed). It is the figure which showed the result of having measured the torque and the drag torque.
FIGS. 2A and 2B are cross-sectional views showing a first embodiment of the eddy current reduction device according to the second aspect of the present invention in the direction of the rotation axis, wherein FIG. 2A is an explanatory view showing a state of braking OFF, and FIG. It is explanatory drawing which shows the state of.
FIGS. 3A and 3B are cross-sectional views showing a second embodiment of the eddy current reduction device according to the second aspect of the present invention in the direction of the rotation axis, where FIG. 3A is an explanatory view showing a state of braking OFF, and FIG. It is explanatory drawing which shows the state of.
4A and 4B are cross-sectional views showing a third embodiment of the eddy current reduction device of the second aspect of the present invention in the direction of the rotation axis, wherein FIG. 4A is a cross-sectional view in the circumferential direction, and FIG. FIG. 6A is a cross-sectional view taken along line A-A, FIG. 5C is a B view of FIG. 4A showing a state of braking OFF, and FIG. 4D is a B view of FIG.
FIG. 5 is a diagram in which the magnetic circuit at the time of braking shown in FIG. 8A is replaced with a current circuit.
6 is a diagram in which the magnetic circuit at the time of non-braking shown in FIG. 8B is replaced with a current circuit.
FIG. 7 is a side view of an eddy current type speed reducer proposed in Japanese Patent Application Laid-Open No. 1-2298948, and is a view showing a cross section of the upper half.
FIGS. 8A and 8B are explanatory diagrams showing a magnetic circuit configuration in the eddy current reduction device of FIG. 7, wherein FIG. 8A is a diagram showing a state in which braking is ON, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1a Cylindrical part 2 Support ring 3 Permanent magnet 4 Switch board 11 1st support ring 11a Groove 11b Notch part 12 Second support ring 12a Protrusion part 13 1st support body

Claims (2)

A rotor that is integrally attached to the rotating shaft and a rotor that is supported opposite to the rotor and that is evenly arranged on the ferromagnetic support ring so that the magnetic poles are opposite to each other along the circumferential direction of the rotor. A permanent magnet group, a ferromagnetic switch plate group that is equally interposed between the permanent magnet group and the rotor, and the switch plates of the switch plate group. In the eddy current type speed reducer provided with the nonmagnetic support member, the circumferential cross-sectional area A of the support ring represented by the following formula is in the range of κ = 0.08 to 0.12. An eddy current type speed reducer characterized by the above.
A = κ · (BHmax · W / ρ) / Br
However, BHmax: Maximum energy product (J / m ³ ) of the permanent magnet used
W: Permanent magnet mass per unit (kg)
ρ: Specific gravity of the permanent magnet used (kg / m ³ )
A: Cross-sectional area in the circumferential direction of the support ring (m ² )
Br: saturation magnetic flux density (T) of the support ring at a magnetic field strength of 5000 A / m A rotor that is integrally attached to the rotating shaft and a rotor that is supported opposite to the rotor and that is evenly arranged on the ferromagnetic support ring so that the directions of the magnetic poles are opposite to each other along the circumferential direction of the rotor. A permanent magnet group, a ferromagnetic switch plate group that is equally interposed between the permanent magnet group and the rotor, and the switch plates of the switch plate group. In the eddy current type speed reducer provided with a nonmagnetic support body portion, the support ring is divided into two in the radial direction, and the cross-sectional area of the support ring is large between adjacent permanent magnets during braking, and adjacent when non-braking An eddy current type speed reducer characterized in that the cross-sectional area of the support ring between the permanent magnets is small.

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