阅读说明：本技术 速度检测装置和速度检测方法 (Speed detection device and speed detection method ) 是由 M·弗兰克尔 A·特伊苏 约翰·W·科拉尔 塚田裕介 中村和人 于 2019-05-29 设计创作，主要内容包括：本发明提供速度检测装置和速度检测方法。速度检测装置(1)具备：磁通产生部(2),其以从相对移动体(6)的一个主面分离的方式配置,以根据相对移动体的移动或旋转来在一个主面上形成磁化图案的方式产生以规定的频率变化的磁通；磁通检测部(3),其以从相对移动体的一个主面分离的方式配置,对根据基于一个主面上的磁化图案的磁通感应出的感应电压进行检测；磁通频率控制部(4),其控制规定的频率,以使由磁通检测部检测出的感应电压为零；以及速度估计部(5),在由磁通检测部检测出的感应电压为零的状态下,该速度估计部基于由磁通频率控制部进行了控制的规定的频率来估计相对移动体的移动速度或旋转速度。(The invention provides a speed detection device and a speed detection method. A speed detection device (1) is provided with: a magnetic flux generating unit (2) that is disposed so as to be spaced apart from one main surface of the relatively movable body (6) and generates magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body; a magnetic flux detection unit (3) which is disposed so as to be spaced apart from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface; a magnetic flux frequency control unit (4) for controlling a predetermined frequency so that the induced voltage detected by the magnetic flux detection unit is zero; and a speed estimation unit (5) that estimates the moving speed or the rotational speed of the relative moving body based on the predetermined frequency controlled by the magnetic flux frequency control unit in a state where the induced voltage detected by the magnetic flux detection unit is zero.)

1. A speed detection device is provided with:

a magnetic flux generating unit that is disposed so as to be spaced apart from one main surface of the relatively movable body and generates a magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body;

A magnetic flux detection unit that is disposed so as to be separated from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface;

a magnetic flux frequency control unit that controls the predetermined frequency so that the induced voltage detected by the magnetic flux detection unit becomes zero; and

And a speed estimating unit that estimates a moving speed or a rotational speed of the relatively movable body based on the predetermined frequency controlled by the magnetic flux frequency control unit in a state where the induced voltage detected by the magnetic flux detecting unit is zero.

2. the speed detection apparatus according to claim 1,

The magnetic flux generating unit includes a rotating body having a permanent magnet rotatable about a rotation axis,

The permanent magnet has a plurality of magnetic poles arranged in the circumferential direction of the rotating body,

The magnetization pattern is formed by magnetic flux from the magnetic pole disposed at a position separated from and opposed to the one main surface of the relatively movable body in accordance with rotation of the rotating body,

The magnetic flux detecting unit includes a detection coil having a diameter corresponding to an interval between the magnetization patterns formed on the one main surface of the relatively movable body,

The magnetic flux frequency control unit makes the moving speed or the rotational speed of the relative moving body coincide with the rotational speed of the rotating body so that the induced voltage detected by the detection coil becomes zero.

3. The speed detection apparatus according to claim 2,

the magnetic flux frequency control unit continuously controls the rotation speed of the rotating body so that the induced voltage detected by the detection coil is zero while the relative moving body moves or rotates.

4. The speed detection apparatus according to any one of claims 1 to 3,

Further comprising a magnetic flux change speed detection unit that detects the predetermined frequency at which the magnetic flux generation unit changes the magnetic flux,

the speed estimating unit estimates the moving speed or the rotational speed of the relatively movable body based on the predetermined frequency detected by the magnetic flux change speed detecting unit in a state where the induced voltage detected by the magnetic flux detecting unit is zero.

5. The speed detection apparatus according to claim 1,

The magnetic flux generating unit includes an exciting coil that generates a magnetic flux that changes the polarity of the magnetization pattern formed on the one main surface of the relatively movable body at the predetermined frequency,

The magnetic flux detection unit includes a detection coil having a predetermined diameter,

The magnetic flux frequency control unit controls the predetermined frequency so that the induced voltage detected by the detection coil is zero,

In a state where the induced voltage detected by the detection coil is zero, the speed estimating unit estimates the moving speed or the rotational speed of the relative moving body based on the diameter of the detection coil and the predetermined frequency controlled by the magnetic flux frequency control unit so that the induced voltage detected by the detection coil is zero.

6. The speed detection apparatus according to claim 5,

The magnetic flux frequency control unit gradually increases the predetermined frequency from a predetermined initial frequency lower than a moving speed or a rotational speed of the relatively movable body, and changes the magnetic flux of the excitation coil at a frequency at which the induced voltage detected by the detection coil is initially zero,

the speed estimating unit estimates the moving speed or the rotational speed of the relative moving body based on a value obtained by multiplying the diameter of the detection coil by the predetermined frequency controlled by the magnetic flux frequency control unit.

7. the speed detection apparatus according to claim 1,

The magnetic flux generating unit includes an exciting coil that generates a magnetic flux that changes the magnetization of the magnetization pattern formed on the one main surface of the relatively movable body at the predetermined frequency,

The magnetic flux detection unit includes a detection coil having a predetermined diameter,

The magnetic flux frequency control unit controls the predetermined frequency so that the induced voltage detected by the detection coil is zero,

the speed estimating unit estimates the moving speed or the rotational speed of the relatively movable body based on the diameter of the detection coil and the predetermined frequency controlled by the magnetic flux frequency control unit in a state where the induced voltage detected by the detection coil is zero.

8. the speed detection device according to claim 7, wherein the magnetic flux generation unit includes:

A permanent magnet that is disposed apart from and opposite to the one main surface of the relatively movable body; and

And a voice coil that changes a gap between the one main surface of the relatively movable body and the permanent magnet at the predetermined frequency.

9. A speed detection device is provided with:

A magnetic flux generating unit that is disposed so as to be spaced apart from one main surface of the relatively movable body and generates a magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body;

a magnetic flux detection unit that is disposed so as to be separated from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface;

A magnetic flux change speed detection unit that detects the predetermined frequency at which the magnetic flux generation unit changes the magnetic flux;

And a speed estimating unit that estimates a moving speed or a rotational speed of the relatively movable body based on the predetermined frequency detected by the magnetic flux change speed detecting unit and the induced voltage detected by the magnetic flux detecting unit.

10. The speed detection apparatus according to claim 9,

further comprising a gap estimation unit that estimates a gap between the magnetic flux generation unit and the one main surface of the relatively movable body,

the speed estimating unit estimates a moving speed or a rotational speed of the relative moving body based on the estimated gap, the predetermined frequency detected by the magnetic flux change speed detecting unit, and the induced voltage detected by the magnetic flux detecting unit.

11. The speed detection apparatus according to claim 10,

the magnetic flux generating unit includes a rotating body having a permanent magnet rotatable about a rotation axis,

the permanent magnet has a plurality of magnetic poles arranged in the circumferential direction of the rotating body,

the magnetization pattern is formed by magnetic flux from the magnetic pole disposed at a position separated from and opposed to the one main surface of the relatively movable body in accordance with rotation of the rotating body,

The clearance estimating section estimates a clearance between an outer peripheral surface of the rotating body and the one main surface of the relatively moving body,

The magnetic flux change speed detection unit detects a rotational speed of the rotating body,

The magnetic flux detection unit includes a detection coil having a predetermined diameter,

the speed estimating unit estimates a moving speed or a rotating speed of the relative moving body based on the estimated gap, the rotating speed of the rotating body, and the induced voltage detected by the detection coil.

12. The speed detection apparatus according to claim 11,

The apparatus further comprises a storage unit for storing correlation data among the gap, the rotational speed of the rotating body, the induced voltage, and the moving speed or rotational speed of the relatively movable body,

the speed estimating unit refers to the correlation data based on the gap estimated by the gap estimating unit, the rotational speed of the rotating body detected by the magnetic flux change speed detecting unit, and the induced voltage detected by the detection coil, and thereby estimates the moving speed or the rotational speed of the corresponding relative moving body.

13. the speed detection apparatus according to claim 11,

The speed estimating unit estimates the moving speed or the rotating speed of the relative moving body based on a calculation result obtained by performing an arithmetic process by substituting the gap estimated by the gap estimating unit, the rotating speed of the rotating body detected by the magnetic flux change speed detecting unit, and the induced voltage detected by the detection coil into a predetermined arithmetic expression.

14. The speed detecting device according to any one of claims 1 to 13,

The relative moving body is a wheel or a track of a train,

The predetermined frequency has a frequency different from a vibration frequency band of the train.

15. A speed detection method, comprising the steps of:

a magnetic flux generating unit that is disposed so as to be separated from one main surface of the relatively movable body and generates a magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body;

A magnetic flux detection unit that is disposed so as to be separated from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface;

controlling the predetermined frequency so that the detected induced voltage is zero; and

And estimating a moving speed or a rotational speed of the relatively movable body based on the predetermined frequency subjected to the control in a state where the induced voltage is zero.

16. A speed detection method, comprising the steps of:

a magnetic flux generating unit that is disposed so as to be separated from one main surface of the relatively movable body and generates a magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body;

A magnetic flux detection unit that is disposed so as to be separated from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface;

detecting the predetermined frequency at which the magnetic flux generated so as to form the magnetization pattern on the one main surface is changed; and

And estimating a moving speed or a rotational speed of the relative moving body based on the detected predetermined frequency and the detected induced voltage.

Technical Field

The present invention relates to a speed detection device and a speed detection method for detecting a speed in a non-contact manner.

background

Patent document 1 discloses a bicycle generator that generates power in a non-contact manner. The bicycle dynamo disclosed in patent document 1 is provided with an outer peripheral surface of an annular permanent magnet extending in a direction orthogonal to a bicycle wheel rotation axis and rotating around the rotation axis, the outer peripheral surface being separated from one side surface continuous to the outer peripheral surface of the wheel.

the permanent magnet is configured by arranging a plurality of magnetic poles along the circumferential direction, and the magnetization directions of the adjacent magnetic poles are opposite. For example, when the wheel rotates in a state where the N-pole of the permanent magnet is disposed to face one side surface of the wheel, an eddy current is generated on the one side surface of the wheel in a direction that hinders a change in magnetic flux from the permanent magnet. The permanent magnet rotates in the rotation direction of the wheel by repulsive force and attractive force between the magnetic flux generated by the eddy current and the magnetic flux from the permanent magnet.

Therefore, inductive power can be obtained from the coil by winding the coil around the permanent magnet and linking the magnetic flux from the permanent magnet to the coil.

The moving speed of the bicycle can be estimated by detecting the rotational speed of the permanent magnet in patent document 1, but the permanent magnet may slip, and when the permanent magnet slips, the moving speed of the bicycle cannot be estimated with high accuracy. Patent document 1 does not disclose any countermeasure for preventing the permanent magnet from slipping, and the moving speed of the bicycle may not be estimated with high accuracy using the method of patent document 1.

Disclosure of Invention

in order to solve the above problem, one aspect of the present invention provides a speed detection device including:

A magnetic flux generating unit that is disposed so as to be spaced apart from one main surface of the relatively movable body and generates a magnetic flux that changes at a predetermined frequency so as to form a magnetization pattern on the one main surface in accordance with movement or rotation of the relatively movable body;

a magnetic flux detection unit that is disposed so as to be separated from one main surface of the relatively movable body and detects an induced voltage induced by magnetic flux based on the magnetization pattern on the one main surface;

a magnetic flux frequency control unit that controls the predetermined frequency so that the induced voltage detected by the magnetic flux detection unit becomes zero;

And a speed estimating unit that estimates a moving speed or a rotational speed of the relatively movable body based on the predetermined frequency controlled by the magnetic flux frequency control unit in a state where the induced voltage detected by the magnetic flux detecting unit is zero.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a speed detection device according to a first embodiment of the present invention.

Fig. 2 is a diagram in which a magnetic flux change speed detection unit is added to the speed detection device of fig. 1.

Fig. 3 is a diagram schematically showing magnetic lines of force generated from the permanent magnets of the rotating body.

Fig. 4 is a graph showing the magnetic flux density interlinked with the detection coil.

Fig. 5 is a diagram showing a schematic configuration of a speed detection device according to a second embodiment.

Fig. 6 is a circuit diagram showing a specific example of the ac power supply.

Fig. 7 is a diagram showing a schematic configuration of a speed detection device according to a third embodiment.

fig. 8A is a graph showing the magnetic flux density when the detection coil is overlapped with two magnetization patterns up and down.

Fig. 8B is a graph showing the magnetic flux density when the positions of the detection coil and the two magnetization patterns are shifted in the vertical direction.

fig. 9 is a diagram showing a schematic configuration of a speed detection device according to a fourth embodiment.

fig. 10 is a diagram showing an example in which one main surface of the relative moving body is disposed to face the outer peripheral surface of the rotating body with a predetermined gap maintained therebetween.

Fig. 11 is a diagram showing a schematic configuration of the speed detection device obtained by adding the gap estimation unit to fig. 9.

fig. 12 is a graph showing the magnetic flux density interlinked with the detection coil.

Detailed Description

An embodiment of the present disclosure is described below with reference to the drawings. In the drawings attached to the present specification, the scale, the vertical and horizontal size ratio, and the like are appropriately changed and enlarged with respect to the actual scale, the vertical and horizontal size ratio, and the like for convenience of illustration and understanding.

Terms used in the present specification to specify shapes, geometrical conditions, and degrees thereof, such as terms of "parallel", "orthogonal", and "the same", and values of lengths and angles, are to be construed as including ranges that can be expected to obtain similar functions, regardless of strict meanings.

(first embodiment)

Fig. 1 is a diagram showing a schematic configuration of a speed detection device 1 according to a first embodiment of the present invention. The speed detection device 1 of fig. 1 includes a magnetic flux generation unit 2, a magnetic flux detection unit 3, a magnetic flux frequency control unit 4, and a speed estimation unit 5.

The magnetic flux generating unit 2 is disposed so as to be spaced apart from the one main surface 6a of the relatively movable body 6, and generates magnetic flux that changes at a predetermined frequency so as to form the magnetization pattern 7 on the one main surface 6a in accordance with movement or rotation of the relatively movable body 6. More specifically, the magnetic flux generating portion 2 may be a rotating body 8, and the rotating body 8 may have a permanent magnet 8a that is freely rotatable about a rotation axis. The permanent magnet 8a has a plurality of magnetic poles 8b arranged in the circumferential direction of the rotating body 8. The magnetization pattern 7 is formed by magnetic flux from a magnetic pole 8b disposed apart from one main surface 6a of the relatively movable body 6 and up to the one main surface 6a in opposition to the rotation of the rotating body 8. Here, the magnetization pattern 7 refers to a range in which the magnetizations are substantially the same, and the magnetization in the magnetization pattern 7 is different from the magnetization in the outer region of the magnetization pattern 7. When a plurality of magnetization patterns 7 are present on the one principal surface 6a of the relatively movable body 6, there is a possibility that the magnetization of each magnetization pattern 7 differs.

The magnetic flux detection unit 3 is disposed so as to be separated from the one main surface 6a of the relatively movable body 6, and detects an induced voltage induced by the magnetic flux based on the magnetization pattern 7. More specifically, the magnetic flux detecting unit 3 includes a detection coil 3a, and the detection coil 3a has a diameter corresponding to the interval between the magnetic poles 8b of the permanent magnet 8a in the magnetic flux generating unit 2.

The number of turns of the detection coil 3a is arbitrary. The magnetic flux detecting unit 3 does not necessarily need to use the detection coil 3a, and may be a member (e.g., a hall element) that detects magnetic flux from the magnetization pattern 7 formed on the one principal surface 6a of the relative movable body 6. Next, an example of using the detection coil 3a as the magnetic flux detection unit 3 will be described.

the magnetic flux frequency control unit 4 controls the frequency at which the magnetic flux generating unit 2 changes the magnetic flux so that the induced voltage detected by the magnetic flux detecting unit 3 becomes zero. More specifically, the magnetic flux frequency control unit 4 matches the moving speed or the rotational speed of the relative moving body 6 with the rotational speed of the rotating body 8 so that the induced voltage detected by the magnetic flux detection unit 3 becomes zero. The magnetic flux frequency control unit 4 may continuously control the rotation speed of the rotating body 8 so that the induced voltage detected by the magnetic flux detection unit 3 becomes zero while moving or rotating relative to the moving body 6.

In a state where the induced voltage detected by the magnetic flux detection unit 3 is zero, the speed estimation unit 5 estimates the moving speed or the rotational speed of the relative moving body 6 based on the frequency controlled by the magnetic flux frequency control unit 4. The speed estimating unit 5 may estimate the moving speed or the rotational speed of the relative moving body 6 based on the frequency generated by the magnetic flux generating unit 2 when the induced voltage detected by the magnetic flux detecting unit 3 is zero, even without detecting the rotational speed of the rotating body 8.

the relatively movable body 6 is a magnetic body in which a magnetization pattern 7 can be formed on one main surface 6a of the relatively movable body 6 by the magnetic flux generating unit 2.

fig. 2 is a diagram in which a magnetic flux change speed detection unit 9 is added to the speed detection device 1 of fig. 1. The magnetic flux change speed detection unit 9 detects the frequency at which the magnetic flux generation unit 2 changes the magnetic flux. When the magnetic flux generating unit 2 is the rotating body 8, the magnetic flux change speed detecting unit 9 detects the rotation speed of the rotating body 8 using a hall element or the like, not shown. In this case, the speed estimation unit 5 estimates the moving speed or the rotational speed of the relative moving body 6 based on the frequency (more specifically, the rotational speed of the rotating body 8) detected by the magnetic flux change speed detection unit 9 in a state where the induced voltage detected by the magnetic flux detection unit 3 is zero. The moving speed or the rotational speed of the relative moving body 6 can be estimated by the following equation (1).

The moving (rotating) speed of the relative moving body 6 is equal to the peripheral speed of the rotating body 8

2 × pi × radius of rotation body 8 × number of revolutions of rotation body 8 … (1)

In an ideal case, the rotating body 8 should rotate at the same rotational speed as the moving speed or the rotational speed of the relative moving body 6, but in reality, the rotational speed of the rotating body 8 is slower than the moving speed or the rotational speed of the relative moving body 6 due to friction or the like. In this specification, a case where the rotational speed of the rotating body 8 is slower than the moving speed or the rotational speed of the relative moving body 6 is referred to as slip of the rotating body 8.

fig. 3 is a diagram schematically showing magnetic lines of force generated from the permanent magnets 8a of the rotating body 8. The permanent magnet 8a of fig. 3 has four magnetic poles (two N poles and two S poles) arranged in the circumferential direction.

The number of magnetic poles of the permanent magnet 8a is not particularly limited. The magnetic lines of force from the N pole go to the adjacent S pole after passing through the one main surface 6a of the relative moving body 6. By these magnetic poles, a magnetization pattern 7 magnetized to the N pole and a magnetization pattern 7 magnetized to the S pole are alternately and closely formed on the surface of the relative moving body 6 in the moving direction of the relative moving body 6. The magnetic lines of force start from each magnetization pattern 7 in a direction corresponding to the polarity. The magnetic lines of force from the respective magnetization patterns 7 are arranged as paths that go forward inside the relative moving body 6 after passing through the air and return to the original magnetization patterns 7.

The size of the magnetization pattern 7 depends on the moving speed or the rotational speed of the relative moving body 6 and the rotational speed of the rotating body 8. If the moving speed or the rotational speed of the relative moving body 6 is equal to the rotational speed of the rotating body 8, the size of each magnetization pattern 7 is fixed regardless of the moving speed or the rotational speed of the relative moving body 6.

for example, when the rotational speed of the rotating body 8 is the same as the moving speed of the relative moving body 6, the detection coil 3a has a diameter obtained by combining the regions of two adjacent magnetization patterns 7 having opposite polarities. Therefore, although the magnetic flux lines from the two magnetization patterns 7 are linked to the detection coil 3a by substantially equal amounts, the magnetic flux linked to the detection coil 3a is cancelled out by the magnetic flux lines from the two magnetization patterns 7 in opposite directions, and becomes substantially zero. Therefore, no induced voltage is generated in the detection coil 3a, and no induced current flows.

the detection coil 3a may have a diameter obtained by combining the sizes of an even number of magnetization patterns 7. For example, when the detection coil 3a has a diameter obtained by combining the sizes of 2n (n is an integer equal to or greater than 1) magnetization patterns 7, n positive magnetic fluxes and n negative magnetic fluxes linked to the detection coil 3a cancel each other, and the induced voltage of the detection coil 3a is zero. For simplicity of description, an example will be described in which the detection coil 3a has a diameter obtained by combining the sizes of the two magnetization patterns 7.

Fig. 4 is a graph showing the magnetic flux density interlinked with the detection coil 3 a. The abscissa of the graph of fig. 4 represents the coordinate position in the moving or rotating direction of the movable body 6, and the ordinate represents the magnetic flux density B [ T ]. The hatched area in fig. 4 indicates the magnetic flux density interlinked with the detection coil 3 a. Since the positive and negative areas of the magnetic flux density interlinking with the detection coil 3a are equal to each other and cancel each other out, no induced voltage is generated in the detection coil 3a and no induced current flows.

In the present embodiment, the magnetic flux frequency control unit 4 controls the frequency of the magnetic flux so that the rotational speed of the rotating body 8 matches the moving speed or the rotational speed of the relatively movable body 6. Thus, the size of the magnetization pattern 7 is controlled to be fixed. Therefore, by making the diameter of the detection coil 3a correspond to the size of the two magnetization patterns 7 in advance, the current flowing in the detection coil 3a is made zero, that is, if the induced voltage induced in the detection coil 3a is zero, it can be determined that the rotation speed of the rotating body 8 matches the moving speed or the rotation speed of the relative moving body 6.

the magnetic flux frequency control unit 4 includes, for example, a motor, not shown, which rotates the rotary shaft of the rotary body 8. The magnetic flux frequency control unit 4 controls the rotation speed of the rotating body 8 by adjusting the rotational driving force of the motor. More specifically, the magnetic flux frequency control unit 4 detects the induced voltage induced in the detection coil 3a by the magnetic flux detection unit 3, and controls the rotation speed of the rotating body 8 based on the detection result so that the induced voltage becomes zero.

In a state where the induced voltage of the detection coil 3a is zero, the speed estimation unit 5 in fig. 1 estimates the moving speed or the rotational speed of the relative moving body 6 based on the magnetic flux frequency controlled by the magnetic flux frequency control unit 4. On the other hand, in a state where the induced voltage of the detection coil 3a is zero, the speed estimation unit 5 in fig. 2 estimates the moving speed or the rotational speed of the relative moving body 6 based on the rotational speed of the rotating body 8 detected by the magnetic flux change speed detection unit 9. If the induced voltage of the detection coil 3a is zero, the rotation speed of the rotating body 8 can be considered to be the same as the moving speed or the rotation speed of the relative moving body 6, and therefore the speed estimating unit 5 can easily estimate the moving speed or the rotation speed of the relative moving body 6.

As described above, in the first embodiment, even if the distance between the relatively movable body 6 and the magnetic flux generating unit 2 changes, the moving speed or the rotational speed of the relatively movable body 6 can be estimated based on the frequency generated by the magnetic flux generating unit 2 when the induced voltage detected by the magnetic flux detecting unit 3 is zero. The present embodiment focuses on a case where the rotating body 8 is disposed at a position separated from and facing the one main surface 6a of the relative moving body 6 and the moving speed or the rotating speed of the relative moving body 6 is estimated based on the rotating speed of the rotating body 8 rotating in accordance with the movement or the rotation of the relative moving body 6, and the moving speed or the rotating speed of the relative moving body 6 cannot be estimated with high accuracy due to a speed difference (slip) between the rotating body 8 and the relative moving body 6. In the present embodiment, in order to detect a state in which the slip of the rotating body 8 is zero, the magnetic flux frequency control unit 4 intentionally drives and rotates the rotating body 8 so that the induced voltage of the detection coil 3a becomes zero. When the induced voltage of the detection coil 3a is zero, it can be determined that the rotation speed of the rotating body 8 matches the moving speed or the rotation speed of the relative moving body 6, and therefore the moving speed or the rotation speed of the relative moving body 6 can be easily estimated based on the rotation speed of the rotating body 8.

in addition, the present embodiment positively utilizes the magnetization pattern 7 formed on the one principal surface 6a of the relatively movable body 6 by the magnetic force of the permanent magnet 8a of the rotating body 8. By matching the rotation speed of the rotating body 8 with the moving speed or the rotation speed of the relatively movable body 6, the sizes of the magnetization patterns 7 on the one main surface 6a of the relatively movable body 6 are made equal. By setting the diameter of the detection coil 3a to the size of the two magnetization patterns 7, the positive magnetic flux and the negative magnetic flux from the magnetization patterns 7 linked with the detection coil 3a when the rotational speed of the rotating body 8 matches the moving speed or the rotational speed of the relative moving body 6 can be cancelled out. Therefore, the moving speed or the rotational speed of the relative moving body 6 can be estimated with high accuracy with a simple configuration without being affected by the gap variation.

(second embodiment)

The second embodiment differs from the first embodiment in the structure of the magnetic flux generating unit 2.

Fig. 5 is a diagram showing a schematic configuration of the speed detection device 1 according to the second embodiment. The speed detection device 1 in fig. 5 includes a magnetic flux generation unit 2, a magnetic flux detection unit 3, a magnetic flux frequency control unit 4, and a speed estimation unit 5, as in the speed detection device 1 in fig. 1.

The magnetic flux generating unit 2 shown in fig. 5 includes an exciting coil 2a for generating a magnetic flux for changing the polarity of the magnetization pattern 7 formed on the one main surface 6a of the relative moving body 6 at a predetermined frequency, and an ac power supply 2b for supplying an ac current to the exciting coil 2 a. The ac power supply 2b switches the frequency of the ac current in accordance with a control signal from the magnetic flux frequency control unit 4. The direction of the current flowing through the exciting coil 2a changes, and thereby the direction of the magnetic flux generated from the exciting coil 2a is reversed. The magnetic flux generated from the excitation coil 2a passes through one main surface 6a of the relatively movable body 6. At this time, a magnetization pattern 7 having a polarity corresponding to the direction of the current flowing through the excitation coil 2a is formed on the one main surface 6a of the relatively movable body 6.

Fig. 6 is a circuit diagram showing a specific example of the ac power supply 2 b. As shown in fig. 6, the magnetic flux generating unit 2 includes an oscillation circuit 2c and an ammeter 2 d. The oscillation circuit 2C has two capacitors C1, C2 connected in series between two terminals to which the dc voltage Udc is applied, and two switches SW1, SW2 also connected in series between the two terminals to which the dc voltage Udc is applied. One end of the excitation coil 2a is connected to a connection point of the two switches SW1, SW2 via the ammeter 2d, and the other end of the excitation coil 2a is connected to a connection point of the two capacitors C1, C2. The switching frequency of the switches SW1 and SW2 can be controlled by a control signal from the magnetic flux frequency control unit 4.

The magnetic flux frequency control unit 4 controls the frequency for switching the direction of the current flowing through the exciting coil 2a so that the induced voltage detected by the detecting coil 3a becomes zero.

the polarity of the magnetization pattern 7 on the one main surface 6a of the relative moving body 6 changes according to the direction of the current flowing in the excitation coil 2a, and therefore the size of the magnetization pattern 7 on the relative moving body 6 can be adjusted by the frequency for switching the direction of the current flowing in the excitation coil 2 a.

in the present embodiment, the diameter of the detection coil 3a is set to a predetermined length in advance. The magnetic flux frequency control unit 4 varies the frequency of the current flowing through the excitation coil 2a, detects a frequency at which the induced voltage of the detection coil 3a is zero, and calculates (estimates) the moving speed or the rotational speed of the movable body 6 by the following equation (2) based on the detected frequency.

The moving (rotating) speed of the relative mover 6 is equal to the diameter of the detection coil 3a × the frequency … (2) of the current flowing through the excitation coil 2a

more specifically, the magnetic flux frequency control unit 4 gradually increases the frequency of the current flowing through the exciting coil 2a with a predetermined low frequency as an initial value, and selects a frequency at which the induced voltage of the detecting coil 3a is initially zero.

in this way, in the second embodiment, the frequency for switching the direction of the current flowing through the exciting coil 2a is controlled so that the induced voltage of the detection coil 3a becomes zero, and the moving speed or the rotational speed of the relative moving body 6 can be estimated easily and accurately from the current switching frequency of the exciting coil 2a at which the induced voltage of the detection coil 3a becomes zero.

In contrast to the first embodiment in which the rotating body 8 is used as the magnetic flux generating unit 2, since a mechanical mechanism for rotating the rotating body 8 is required, in the second embodiment in which the exciting coil 2a is used as the magnetic flux generating unit 2, the direction of the current flowing through the exciting coil 2a only needs to be switched, and a mechanical mechanism is not required, and therefore, the magnetic flux generating unit is less likely to be damaged and has excellent maintenance performance.

(third embodiment)

In the third embodiment, the voice coil portion is used as the magnetic flux generating portion 2.

Fig. 7 is a diagram showing a schematic configuration of the speed detection device 1 according to the third embodiment. The speed detection device 1 in fig. 7 includes a magnetic flux generation unit 2, a magnetic flux detection unit 3, a magnetic flux frequency control unit 4, and a speed estimation unit 5, as in the speed detection device 1 in fig. 1.

the magnetic flux generating unit 2 of fig. 7 has a voice coil unit 21. The voice coil portion 21 includes a permanent magnet 21a, a voice coil 21b, and a spring member 21c, wherein both magnetic poles of the permanent magnet 21a are arranged in a normal direction with respect to the one main surface 6a of the moving body 6, the voice coil 21b is wound around the permanent magnet 21a, and the spring member 21c is connected to one end side of the permanent magnet 21 a. When an alternating current is supplied from the power source 21d to the voice coil 21b, the permanent magnet 21a receives a force to expand and contract the spring member 21c, and the gap between the magnetic pole on the other end side of the permanent magnet 21a and the one main surface 6a of the relatively movable body 6 changes.

When a current flows in the voice coil 21b, the permanent magnet 21a is subjected to a force due to a lorentz force acting between the voice coil 21b and the magnetic field of the permanent magnet 21 a. The direction of the lorentz force also changes depending on the direction of the current flowing through the voice coil 21b, and thus the permanent magnet 21a vibrates according to the current switching frequency of the voice coil 21b, and the gap between the tip of the magnetic pole on the other end side of the permanent magnet 21a and the one main surface 6a of the relatively movable body 6 changes.

the smaller the gap, the stronger the magnetization of the magnetization pattern 7 on the one main surface 6a of the relatively movable body 6, and the larger the gap, the weaker the magnetization of the magnetization pattern 7 on the one main surface 6a of the relatively movable body 6. Therefore, two kinds of magnetization patterns 7 having different magnetization intensities are alternately formed on the one main surface 6a of the relatively movable body 6 in synchronization with the vibration of the permanent magnet 21 a.

In the first and second embodiments, two kinds of magnetization patterns 7 having different polarities are alternately formed on the one main surface 6a of the relatively movable body 6, but in the present embodiment, two kinds of magnetization patterns 7 having different degrees of magnetization are alternately formed.

The detection coil 3a has, for example, a diameter corresponding to the size of the adjacent two magnetization patterns 7. Therefore, the magnetic fluxes from the adjacent two magnetization patterns 7 are linked with the detection coil 3 a. These magnetic fluxes are in the same direction, and therefore the magnetic fluxes do not cancel as in the first and second embodiments.

Fig. 8A and 8B are graphs showing the magnetic flux density interlinked with the detection coil 3 a. The abscissa of these graphs represents the coordinate position in the moving direction or the rotating direction of the movable body 6, and the ordinate represents the magnetic flux density B [ T ]. When one cycle of the intensity of the magnetization pattern 7 is included between the detection coils 3a, the magnetic flux density linked with the detection coils 3a is a graph as shown in fig. 8A. In this case, since the magnetic flux linked with the detection coil 3a is always constant and the magnetic flux does not change, no induced voltage is generated in the detection coil 3 a. When one cycle of the intensity of the magnetization pattern 7 is not included between the detection coils 3a, the magnetic flux density linked with the detection coils 3a is a graph as shown in fig. 8B. In this case, since the magnetic flux linked with the detection coil 3a changes with time, an induced voltage is generated in the detection coil 3 a.

therefore, the magnetic flux frequency control unit 4 controls the current switching frequency of the voice coil 21b so that the induced voltage detected by the sense coil 3a becomes zero, and estimates the moving speed or the rotational speed of the relative moving body 6 based on the diameter of the sense coil 3a and the current switching frequency of the voice coil 21b at which the induced voltage becomes zero.

In this way, in the third embodiment, the current switching frequency of the voice coil 21b is controlled so that the induced voltage detected by the sense coil 3a is zero, whereby the moving speed or the rotational speed relative to the moving body 6 can be estimated based on the diameter of the sense coil 3a and the current switching frequency of the voice coil 21b at which the induced voltage is zero. In the third embodiment, by using the permanent magnet 21a having a strong magnetic force, even if the current flowing through the voice coil 21b is small, the magnetization pattern 7 can be formed on the one principal surface 6a of the relatively movable body 6, and there is a possibility that the power consumption is reduced as compared with the first and second embodiments.

(fourth embodiment)

In the first and second embodiments, the rotation speed of the rotating body 8 is controlled in accordance with the moving speed or the rotation speed of the relative moving body 6, or the current switching frequency of the exciting coil 2a is controlled, but a configuration in which such control is not performed may be considered.

Fig. 9 is a diagram showing a schematic configuration of the speed detection device 1 according to the fourth embodiment. The speed detection device 1 shown in fig. 9 includes a magnetic flux generation unit 2, a magnetic flux detection unit 3, a magnetic flux change speed detection unit 9, and a speed estimation unit 5. The magnetic flux generating unit 2 and the magnetic flux detecting unit 3 are the same as those of fig. 5.

The magnetic flux generating unit 2 may be, for example, a rotary body 8 that is rotatable about a rotation axis, but the rotary body 8 of the present embodiment rotates by a magnetic flux generated by an eddy current generated in the one main surface 6a of the relatively movable body 6 according to the moving speed or the rotation speed of the relatively movable body 6. Since the speed detection device 1 of fig. 9 does not include the magnetic flux frequency control unit 4 of fig. 1, the rotating body 8 performs a passive rotating operation that rotates at a rotation speed corresponding to the moving speed or the rotation speed of the relative moving body 6. Therefore, the rotational speed of the rotating body 8 is equal to or less than the moving speed of the relative moving body 6. That is, the difference between the rotation speed of the rotating body 8 and the moving speed or the rotation speed of the relative moving body 6 is a necessary condition for the rotation of the rotating body 8.

Fig. 10 is a diagram showing an example in which the one main surface 6a of the relative moving body 6 is disposed to face the outer peripheral surface of the rotating body 8 with a predetermined gap maintained between the main surface and the outer peripheral surface of the rotating body 8. The one principal surface 6a of the relative moving body 6 may be a flat surface or a curved surface. As a typical example, the relatively movable body 6 is a rotary body, and one main surface 6a of the relatively movable body 6 is an outer peripheral surface of the rotary body.

the relatively movable body 6 moves in the magnetic flux from each magnetic pole 8b of the permanent magnet 8a of the rotating body 8, and thereby an eddy current is generated on one main surface 6a of the relatively movable body 6. The direction of the eddy current depends on the direction of movement of the relative moving body 6. In the present specification, an example of the relative moving body 6 itself is described, but the movement of the relative moving body 6 also includes a case where the relative moving body 6 itself stops and the rotating body 8 moves. That is, the movement of the relative moving body 6 refers to the relative movement of the relative moving body 6 and the rotating body 8. The gap between the one main surface 6a of the relatively movable body 6 and the rotating body 8 is limited to a range that can be reached by the magnetic flux from each magnetic pole 8b of the permanent magnet 8a of the rotating body 8.

Each magnetic pole 8b of the permanent magnet 8a is magnetized in a direction going toward the one principal surface 6a of the opposing relatively movable body 6 or in a direction opposite to the direction. In addition, the adjacent magnetic poles 8b of the permanent magnet 8a are opposite in magnetization direction to each other. The magnetization direction of each magnetic pole 8b of the permanent magnet 8a is shown by an arrow in fig. 10.

As shown in fig. 10, an eddy current is generated on the one main surface 6a of the relatively movable body 6 in accordance with the polarity of the magnetic pole of the permanent magnet 8a disposed so as to face the one main surface 6a of the relatively movable body 6. When the relatively movable body 6 moves or rotates, an eddy current is generated in the direction of blocking the change in magnetic flux from the rotating body 8 on the one main surface 6a of the relatively movable body 6, and the rotating body 8 rotates due to the interaction (repulsive force and attractive force) between the magnetic flux generated by the eddy current and the magnetic flux from the rotating body 8. However, the surface speed of the one main surface 6a of the rotating body 8 is lower than the surface speed of the one main surface 6a of the opposing relative moving body 6.

For example, when the N pole of the rotating body 8 is disposed to face the one main surface 6a of the relatively movable body 6, the direction of the eddy current 12a generated in the portion of the one main surface 6a of the relatively movable body 6 where the magnetic flux from the edge e1 of the N pole forward in the rotational direction reaches is different from the direction of the eddy current 12b generated in the portion of the one main surface 6a of the relatively movable body 6 where the magnetic flux from the edge e2 of the N pole rearward in the rotational direction reaches. The eddy current 12b generated by the magnetic flux from the edge e2 on the rear side in the rotation direction of the N pole flows in a direction in which the magnetic flux in the opposite direction to the magnetic flux from the N pole is generated. On the other hand, the eddy current 12a generated in the portion of the one main surface 6a of the relatively movable body 6 where the magnetic flux from the edge e1 of the N pole located forward in the rotation direction reaches flows in the direction in which the magnetic flux from the N pole is generated. Both of the eddy currents 12a and 12b flow in a direction of preventing the magnetic flux from the rotating body 8 from changing with the rotation of the relative moving body 6.

As described above, on the edge e1 side of the rotating body 8 in front of the N pole in the rotating direction, the magnetic flux generated by the eddy current 12a and the magnetic flux from the N pole of the rotating body 8 have the same direction, and therefore, an attractive force attracting each other acts. On the other hand, on the edge e2 side of the rotor 8 on the rear side in the rotation direction of the N pole, the magnetic flux generated by the eddy current 12b is opposite in direction to the magnetic flux from the N pole of the rotor 8, and hence repulsive forces that repel each other act. When the surface speed of the outer peripheral surface of the rotating body 8 is lower than the surface speed of the one main surface 6a of the opposing relative moving body 6, the above-described relationship between the rotating body 8 and the eddy currents 12a and 12b is always established. Thereby, the rotating body 8 rotates at a surface speed slower than the surface speed of the one main surface 6a of the opposing relative moving body 6 so as to follow the moving surface of the one main surface 6a of the opposing relative moving body 6.

the principle of rotation of the rotating body 8 described above can also be explained by the reaction force of the lorentz force. As described above, the eddy current 12a generated by the magnetic flux from the edge e1 on the forward side in the rotational direction of the N pole of the rotor 8 is opposite in direction to the eddy current 12b generated by the magnetic flux from the edge e2 on the backward side in the rotational direction of the rotor 8, and a current in a fixed direction flows immediately below the N pole. When the relative moving body 6 rotates in the direction of the arrow in fig. 10, the currents based on these eddy currents 12a and 12b receive a lorentz force in the direction opposite to the direction of rotation of the relative moving body 6. Therefore, the rotating body 8 receiving the magnetic flux generated by the eddy currents 12a and 12b rotates by the reaction force of the lorentz force in the direction of rotation of the relative moving body 6. Thus, the facing surfaces of the rotating body 8 and the relative moving body 6 move in the same direction.

the magnetic flux change speed detection unit 9 in fig. 9 detects the frequency at which the magnetic flux generation unit 2 changes the magnetic flux. The speed estimating unit 5 preliminarily examines the correspondence relationship between the frequency at which the magnetic flux generating unit 2 changes the magnetic flux and the moving speed or the rotational speed of the relative moving body 6, tabulates the correspondence relationship, and estimates the moving speed or the rotational speed of the relative moving body 6 with reference to the table based on the frequency detected by the magnetic flux change speed detecting unit 9. Instead of tabulating, a functional expression representing the above correspondence relationship may be prepared in advance, and the moving speed or the rotational speed of the relative moving body 6 may be estimated by substituting the frequency detected by the magnetic flux change speed detection unit 9 into the functional expression.

The rotation speed of the rotating body 8 varies depending on the distance (gap) between the one main surface 6a of the relative moving body 6 and the outer peripheral surface of the rotating body 8. Therefore, the gap estimating unit 11 may be provided in the speed detecting device 1 as shown in fig. 11.

The gap estimating unit 11 is provided with a coil, not shown, at a position linked with the magnetic flux of the permanent magnet 8a of the rotating body 8, for example, and estimates the gap between the relative moving body 6 and the exciting coil 2a based on the current and the induced voltage flowing through the coil.

The gap estimation unit 11 estimates the gap by an impedance analysis method. More specifically, the gap estimating unit 11 estimates the gap by comparing the inductance of the coil calculated based on the current and the induced voltage flowing through the coil with the inductance of the coil corresponding to a predetermined reference value of the gap.

Fig. 12 is a graph showing the magnetic flux density linked with the detection coil 3 a. The abscissa of the graph of fig. 12 represents the coordinate position in the moving or rotating direction of the movable body 6, and the ordinate represents the magnetic flux density B [ T ]. Unlike the graph of fig. 4, in the graph of fig. 12, the amount of magnetic flux linked with the detection coil 3a is not equal in the positive and negative directions, and an induced voltage is induced in the detection coil 3 a.

the speed estimating unit 5 estimates the moving speed or the rotating speed of the relative moving body 6 based on the rotating speed of the rotating body 8 detected by the magnetic flux change speed detecting unit 9, the induced voltage of the detection coil 3a detected by the magnetic flux detecting unit 3, and the gap estimated by the gap estimating unit 11, taking the gap into consideration. The correspondence relationship between the rotation speed of the rotating body 8, the induced voltage of the detection coil 3a, and the gap and the moving speed or rotation speed of the relative moving body 6 may be tabulated in advance, and the moving speed or rotation speed of the relative moving body 6 may be estimated by referring to the table. Alternatively, the moving speed or the rotational speed of the relative moving body 6 may be calculated by inputting the rotational speed of the rotating body 8, the induced voltage of the detection coil 3a, and the gap into the arithmetic expression obtained by converting the above-described correspondence relationship into an arithmetic expression.

In this way, in the fourth embodiment, since the moving speed or the rotational speed of the relative mobile body 6 can be estimated without performing the rotation control of the rotating body 8, the configuration can be further simplified as compared with the speed detection devices 1 of the first to third embodiments. Further, the moving speed or the rotational speed of the relative moving body 6 can be estimated by taking into consideration the gap between the rotating body 8 and the one principal surface 6a of the relative moving body 6, and the estimation accuracy can be improved.

The concept of the relative moving body 6 in the above-described first to fourth embodiments includes not only an object that moves or rotates by itself but also an object that moves relatively with respect to the speed detection device 1. Therefore, in the first to fourth embodiments, when the speed detection device 1 is mounted on a train or the like, it is explained that a fixed object such as a track that moves relative to the train or the like is also included in the relatively moving body 6.

The embodiments of the present invention are not limited to the above embodiments, and include various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the above. That is, various additions, modifications, and partial deletions can be made without departing from the scope of the general concept and spirit of the present invention derived from the contents defined in the claims and their equivalents.