JP3406501B2 - Displacement sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement sensor that converts a mechanical displacement amount into an electric signal.

[0002]

2. Description of the Related Art A displacement sensor for converting a mechanical displacement amount into an electric signal is, for example, a torque applied to a crank shaft which is rotated by human power when a bicycle with electric power assist is driven by a displacement mechanism in the axial direction of the crank shaft. It is used in various devices such as a torque detecting means for converting the mechanical displacement amount into a mechanical displacement amount and converting the displacement amount into an electric signal.

There are various types of displacement sensors. For example, the one used in the bicycle with the electric auxiliary power described above applies the torque applied to the crankshaft by depressing the pedal and the rear wheel through the chain. A mechanism that converts the difference between the torque applied to the hollow shaft for rotation into a mechanical displacement amount by the displacement mechanism and operates the slider of the variable resistor, that is, the movable contact by the movable portion of this displacement mechanism, or In addition to the strain gauge such as the load cell through the movable part mechanical displacement amount by the displacement mechanism,
A system of taking out the change of the strain gauge as an electric output is used.

Further, it is composed of an operating body provided with a core, and a coil formed in a cylindrical shape and arranged on the outer periphery of the core of the operating body. A condenser is connected to this coil to move the operating body of a displacement mechanism. The inductance of the coil is changed by the interaction between the core and the coil which is moved by the part and moves together with the actuating body, and the change in the oscillation frequency caused by the changing inductance and the capacitor is detected, and the displacement based on this frequency is detected. There is a displacement sensor that detects the amount. This type of displacement sensor is advantageous in that it is not easily affected by noise and can accurately assist power over a long period of time.

However, the actuating body of the displacement sensor is constructed so as to come into pressure contact with the movable portion of the displacement mechanism by means of a coil spring provided in the housing, that is, the case. Since the coil spring is made of metal, it has a high magnetic permeability. Therefore, when the coil spring approaches the coil, the inductance of the coil changes, which affects the transmission frequency and hinders normal operation. .

[0006]

DISCLOSURE OF THE INVENTION As described above, a displacement sensor of the type including a conventional actuating body provided with a core and a coil formed in a tubular shape and arranged on the outer circumference of the core of the actuating body. Has a problem in that the coil spring for pressing the actuating body against the movable portion of the displacement mechanism affects the inductance of the coil, so that the accurate displacement amount cannot be detected.

[0007]

DISCLOSURE OF THE INVENTION The present invention is directed to the above-mentioned problems of a displacement sensor of the type including an operating body provided with a core and a coil formed in a cylindrical shape and arranged on the outer periphery of the core of the operating body. And a displacement sensor capable of preventing a malfunction caused by vibration or the like which the displacement sensor receives from the outside. The invention according to claim 1 has an operating body having a core and a coil, and In a displacement sensor that detects a displacement amount by detecting an oscillation frequency that changes with a coil inductance that changes with a core that moves with movement and a capacitor that is connected to the coil, the displacement sensor has a first guide hole. A first case formed into a box with a bottom and having a storage chamber formed inside by the formed bottom wall and the peripheral wall formed integrally with the outer peripheral portion and having one end side as an opening. The same as the guide hole, and a second case which is located on the opening side of the first case and is attached to the first case and provided with a spring support portion corresponding to the first guide hole. A frame member having a second guide hole with a diameter and having its axis aligned with the first guide hole and disposed in the storage chamber; and a frame member located on the outer periphery of the second guide hole. And a coil formed in a bottomed cylindrical shape with one end side opened and the other end side acting as a working surface, and a flange portion is provided on the outer periphery of the opening edge, and this flange portion is formed into the hole of the second guide hole. A first cylindrical body in which the working surface projects a predetermined length from the first guide hole when brought into contact with the edge surface, and one end side is brought into contact with the bottom wall of the first cylindrical body And a spring receiving collar that abuts against the collar portion on one end side, and the other end side end surface is the other end surface of the core. An actuating body formed of a second cylinder body provided in the first cylinder body by being brought into contact with and fitted into the first cylinder body, the spring support portion of the second case, and the second frame member of the frame member. The displacement sensor includes a coil spring which is disposed between the guide hole and the edge surface of the hole and biases the actuating body so that the working surface projects from the first guide hole.

According to the first aspect of the present invention thus constructed, the coil is provided in the storage chamber provided in the first case having the first guide hole, and the coil has the same axial center as that of the first guide hole. A frame member having a second guide hole is provided, and a flange portion of a first cylindrical body of an actuating body that moves axially in the both guide holes and a second cylindrical body fitted into the first cylindrical body. Since the spring receiving flange portions of the cylindrical body are brought into contact with each other so as to overlap each other, and one end side of the coil spring is brought into contact with this spring receiving flange portion, at least the coil spring and the coil are provided with the overlapped flange portion. And the spring receiving flange portion can be separated from each other by the thickness distance, the inductance of the coil can be prevented from being influenced by the coil spring, and the displacement amount can be accurately detected.

Further, the spring supporting flange of the second cylindrical body, which is inserted into the first cylindrical body and presses the other end surface of the core housed in the first cylindrical body, is formed by a coil spring. Since it is pressed against the collar, it is prevented from slipping out of the first cylindrical body, so it is possible to reliably prevent axial displacement of the core in the first cylindrical body due to vibration, etc. It has the effect of preventing the decrease.

According to a second aspect of the invention, in the invention of the first aspect, a frame member is attached to either the first case or the second case, and the frame member of both cases is This is a displacement sensor in which an attached portion for attaching to the attached portion is provided in the attached case.

As described above, the invention according to claim 2 is the invention according to claim 1, wherein a frame member is attached to either one of the first case and the second case, and
Of these two cases, the case to which the frame member is attached is provided with the attaching portion for attaching to the attached portion,
In addition to the effect of the invention described in claim 1, when the displacement sensor is attached to the attached portion via the attachment portion of the case, the positional accuracy of the coil provided in the frame member and the core provided in the actuating body is improved. It has the effect of being able to.

According to a third aspect of the present invention, in the first aspect of the present invention, an attaching portion for attaching to the attached portion is provided in the first case, and the attaching portion is parallel to the moving direction of the operating body. The displacement sensor is formed by a mounting hole having a different axis, and a mounting hole for mounting the frame member is formed coaxially with the mounting hole.

As described above, according to the invention of claim 3, in the invention of claim 1, the first case is provided with a mounting portion for mounting to the mounted portion, and the mounting portion is arranged in the moving direction of the operating body. In addition to the function of the invention of claim 1, the mounting hole is formed by the mounting holes having parallel axes and the frame member is formed coaxially with the mounting hole. Since the mounting portion and the portion forming the mounting hole to which the frame member is mounted can be the same portion, it is possible to prevent distortion of the case due to the formation of the mounting hole.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a plan view of the displacement sensor 1, FIG. 2 is a side view, and FIG. 3 is a sectional view taken along line XX of FIG.

In the figure, reference numeral 10 is a first case, and the first case 10 is composed of a bottom wall 11 and a peripheral wall 12 formed integrally with the outer peripheral portion of the bottom wall 11, and FIG.
At the bottom, that is, in the shape of a box with a bottom, one end of which has an opening 13. A cylindrical wall 14 is formed integrally with the bottom wall 11 so as to project outward at a substantially central portion thereof, and the first guide hole 1 is formed inside the cylindrical wall 14.
5 is formed.

A mounting projection 16 (only one of which is shown in FIGS. 2 and 3) for mounting a pair of second cases 20 to be described later is formed on the peripheral wall 12 on the side of the opening 13 as shown in the drawing. The mounting protrusion 16 has a screw hole 16a in which a female screw is formed. In addition, a screw hole 12a is formed in a portion of the peripheral wall 12 in which the mounting protrusion 16 is formed, in which a female screw is formed as a mounting portion having the same axis as the screw hole 16a.
Further, as shown in FIG. 3, the screw hole 16a and the screw hole 12a are in communication with each other.

Further, the peripheral wall 12 is formed with a pair of mounting holes 17 on its opening side, in which female screws for mounting a frame member 30 described later are formed. Further, the peripheral wall 12 is formed with a screw hole 12a in which a female screw is formed as a mounting portion formed with the same axis as the mounting hole 17.

The four screw holes 12a (see FIG. 1) formed in the peripheral wall 12 as mounting portions have a displacement detection portion in which the first case 10, that is, the displacement sensor 1 is mounted as a mounting portion. It is for attaching to the device.

The bottom wall 1 of the first case 10 is also used.
The inside surrounded by 1 and the peripheral wall 12 is a storage chamber 18.

Next, the second case 20 attached to the opening 13 side of the first case 10 has a bottom wall 21.
And an annular wall 22 formed integrally with the outer peripheral portion of the bottom wall 21.
3, the bottomed tubular portion 23 having the opening 24 on the upper side, that is, the first case 10 side, and the bottomed tubular portion 2
3 is formed of a flat plate-like flange portion 26 having an outer shape corresponding to the opening 13 of the first case 10 on the outer periphery in the vicinity of the rim of the opening 24.

The bottom wall 21 is formed with an annular rib 21a into which the inner diameter of a coil spring 60, which will be described later, is fitted. The portion of the bottom wall 21 outside the annular rib 21a is the coil spring 60. The spring support portion 27 supports one end side. The spring support portion 27 has a positional relationship corresponding to the first guide hole 15 when the second case 20 is attached to the first case 10. Has become.

A pair of fitting portions 28 (only one of which is shown in FIG. 3) is fitted on the flange portion 26 with a tip portion of a mounting projection 16 formed on the peripheral wall 12 of the first case 10.
The annular rib 28a that forms the
A hole 28b is formed in the central portion surrounded by 8a.
Then, the tip end portion of the mounting protrusion 16 of the first case 10 is fitted into the fitting portion 28 of the second case 20, and the screw 29 is inserted into the hole 28b and screwed into the screw hole 16a. The case 20 is attached to the first case 10.

Next, the frame member 30 arranged in the storage chamber 18 formed in the first case 10 will be described.

As shown in FIG. 3, the frame member 30 is integrally formed on a small-diameter cylindrical portion 31 having a small diameter on the upper side, that is, on the bottom wall 11 side of the first case 10, and on the lower side of the small-diameter cylindrical portion 31. And a cylindrical portion 33 formed of a large-diameter cylindrical portion 32 that is larger in diameter than the small-diameter cylindrical portion 31.
A second guide hole 35 having the same diameter as that of the first guide hole 15 formed in the first case 10 is formed therein. The second guide hole 35, when the frame member 30 is attached to the first case 10,
The axial center of the first guide hole 15 and the axial center of the first guide hole 15 are aligned with each other.

A coil 40 is attached to the small-diameter cylindrical portion 31.
Is wound on both ends of the winding of the coil 40,
As shown in the circuit diagram of FIG. 4, capacitors C1 and C2 are connected in parallel. The capacitors C1 and C
Although not shown, 2 is provided in the first case 10.

Further, a mounting hole 34 as a mounting portion corresponding to the pair of mounting holes 17 formed in the first case 10 is provided on the outer peripheral portion of the large-diameter cylindrical portion 32, and the mounting hole 34 is provided. The frame member 30 is attached to the first case 10 by inserting the screw 39 into the mounting hole 17 and screwing it into the mounting hole 17.

An annular wall 36 having a diameter larger than that of the second guide hole 35 is formed on the lower end side of the second guide hole 35 of the large-diameter cylindrical portion 32. By forming the hole, the hole edge face 37 is formed at the hole edge of the second guide hole 35.

Next, the actuating member 50 is disposed in the first guide hole 15 formed in the first case 10 and the second guide hole 35 formed in the second case so as to be movable in the axial direction.
Will be described.

As shown in FIG. 3, the operating body 50 is a first cylindrical body 5 having a bottomed cylindrical shape with an opening 51 on the lower side.
2. A second cylinder 56 and a core 58 that are fitted inside the first cylinder 52.

The outer diameter of the first cylindrical body 52 is set to be slightly smaller than the inner diameters of the first guide hole 15 and the second guide hole 35. It is movable in the guide hole 35 in the axial direction. Further, the outer surface of the bottom wall 52a is an action surface 54, and the action surface 54 is pressed against the movable body 70 of the displacement detection part of the device indicated by the chain double-dashed line by the biasing force of the coil spring 60. Has become. Further, the bottom wall 52a is provided with a protrusion 52c at the center thereof.

An annular flange 53 having a diameter larger than the diameter of the second guide hole 35 is formed on the outer periphery of the opening 51 of the first cylindrical body 52. Three
In, the upper surface comes into contact with the hole edge surface 37.

The core 58 housed in the first cylindrical body 52 is formed of a magnetic material such as ferrite in a columnar shape, and a through hole 58a is formed in the central portion for penetrating the protrusion 52c. The projection 52c is passed through the through hole 58a and is housed in the first cylindrical body 52.

Further, the second cylindrical body 56 is formed as a bottomed cylindrical body having an opening 57 on the lower side in FIG. 3, and a through hole 56 through which the projection 52c penetrates is formed in a bottom wall 56a thereof.
b is formed, and an annular spring receiving flange 57a having the same shape as the flange portion 53 formed on the outer circumference of the rim of the opening 51 of the first cylindrical body 52 is formed on the outer periphery in the vicinity of the opening 57. There is. The upper surface of the spring receiving collar 57a is always in contact with the flange portion 53 by the urging force of the coil spring 60.

The coil spring 60 is disposed between the spring support portion 27 of the second case 20, the spring support collar 57a of the second cylindrical body 56 and the end portion thereof in contact with each other. The actuation body 50 is biased upward in FIG. 3, and the biasing of the coil spring 60 causes the working surface 53 of the actuation body 50 to project from the first guide hole 15 of the first case 10 by a predetermined length. It is in a state.

The displacement sensor 1 constructed as described above is assembled by the coil 40 of the first case 10.
The frame member 30 wound with is attached by a screw 39, the core 58 is housed or inserted in the first cylindrical body 52, and the second cylindrical body 56 is inserted to assemble the operating body 50 into the first case. 10 is arranged so as to penetrate the first guide hole 15 and the second guide hole 35 of the frame member 30, and then one end side of the coil spring 60 is fitted to the annular rib 21a of the second case 20. The other end side of the coil spring 60 is brought into contact with the spring support collar 57a of the second cylindrical body 56, and the second case 20 is attached to the first case 10 with the screw 29. 1 and 2, reference numeral 45 is a terminal.

The electric circuit of the displacement sensor 1 is shown in FIG.
It is configured as shown in. That is, the coil 40
Are connected in parallel with capacitors C1 and C2, and this coil 40 and the capacitor C connected to this coil 40
1 and C2 form a transmission (resonance) circuit 41, and
A detection circuit 42 is connected to the transmission circuit 41.
The resistors R1 to R3 in the detection circuit 42 are protective resistors, and U1 to U3 are inverters. The output of the detection circuit 42 is amplified by an amplifier (not shown) and is output to the frequency detection circuit 43. The output of the frequency detection circuit 43 is sent to control means (not shown).

In the displacement sensor 1, when the movable body 70 of the displacement detection section operates, that is, when the displacement acts on the actuation body 50, the actuation body 50 moves in the axial direction and the core 58 becomes a coil. Move relative to 40.
When the relative movement of the core 58 with respect to the coil 40 occurs, the inductance of the coil 40 changes, and the oscillation frequency transmitted by the oscillation circuit 41 changes as the inductance changes, as is well known. The amount of displacement of the movable body 70 is detected based on the frequency that changes according to the amount of change in inductance.

The displacement sensor 1 assembled as described above is attached to a device as an attached portion having an unillustrated displaced detection portion. When the movable body 70 of the displacement detection section moves or is displaced in the direction of the arrow in FIG. 3 according to the displacement amount, the actuating body 50 moves in response to the movement of the movable body 70. The core 58 moves in the guide hole 35 in the axial direction, and the amount of insertion / removal of the core 58 into / from the coil 40 changes with the movement of the actuating body 50. As a result, the inductance of the coil 40 changes as described above. Capacitors C1 and C connected to
The transmission frequency to be transmitted changes depending on 2. The displacement amount of the displacement detection part is detected based on this transmission frequency.

Although not shown, the capacitors C1 and C2 are housed in the first case 10.

The displacement sensor 1 constructed as described above is
In the coil spring 60 and the coil 40 wound around the frame member 30, since the collar portion 53 of the first cylindrical body 52 and the spring supporting collar 57a of the second cylindrical body 56 have a predetermined thickness, respectively. , Coil spring 60 and coil 4
Since the separation distance from 0 is separated by the collar portion 53 and the spring supporting collar 57a at least by the collar portion 53 and the spring supporting collar 57a, the inductance of the coil 40 can be prevented from being influenced by the coil spring 60. is there.

Further, the spring support flange 57a of the second cylindrical body 56 of the actuating body 50 is pressed against the flange portion 53 of the first cylindrical body 52 by the urging force of the coil spring 60. Since the cylindrical body 56 urges the core 58 against the bottom wall 52a of the first cylindrical body 52, when the device is, for example, a bicycle with electric power assist, vibration occurs during traveling, etc. Even when such a vibration occurs, the core 58 is pressed into the first cylindrical body 52 by the second cylindrical body 56 by the coil spring 60. Are prevented from moving in.

This means that the core 58 and the second cylindrical body 56 are
Even if the adhesive is stored in the first cylindrical body 52 by adhesion or the like, the adhesive strength may be lost due to the aging of the adhesive. In such a case, the core 58 can be reliably positioned at a predetermined position. It is possible.

Further, the frame member 3 around which the coil 40 is wound.
When the displacement sensor 1 is attached to the attached portion via the screw hole 12a, the first case 10 to which 0 is attached is provided with the screw hole 12a as the attaching portion to be attached to the device which is the attached portion. In addition, the positional relationship between the coil 40 provided on the frame member 30 and the core 58 provided on the actuation body 50 does not shift, that is, the accuracy of the positional relationship between the coil 40 and the core 58 provided on the actuation body 50 can be improved. It is a thing.

When the frame member 30 is attached to the second case 20, the attachment portion is the second case 20.
Similarly, in the case of forming the coil and the actuator 50 as well.
It is possible to improve the positional relationship accuracy of the core provided in the.

A screw hole 12a, which is a mounting portion for mounting the mounting portion on the first case 10, is provided as an axis parallel to the moving direction of the operating body 50, and is coaxial with the screw hole 12a. Since the mounting hole 17 for mounting the screw 30 is formed, the number of portions where the screw holes 12a and 17 are formed in the first case 10 can be reduced, so that the case resulting from the formation of the screw holes 12a and 17 can be reduced. It is possible to prevent the occurrence of distortion.

[0047]

According to the first aspect of the present invention configured as described above, the coil is provided in the storage chamber provided in the first case having the first guide hole and the same axis as the first guide hole is provided. A frame member having a centered second guide hole is arranged, and is fitted into the flange portion of the first cylindrical body of the actuating body which moves axially in the both guide holes and the first cylindrical body. Since the spring receiving portion of the second cylindrical body is brought into contact with and overlapped with one another and the one end side of the coil spring is brought into contact with this spring receiving portion, the coil spring and the coil are at least overlapped with each other. The flange portion and the spring receiving collar portion can be separated from each other by the thickness distance, and the inductance of the coil can be prevented from being affected by the coil spring, and the displacement amount can be accurately detected.

Further, the spring supporting flange of the second cylindrical body, which is inserted into the first cylindrical body and presses the other end surface of the core housed in the first cylindrical body, is formed by a coil spring. Since it is pressed against the collar, it is prevented from slipping out of the first cylindrical body, so it is possible to reliably prevent axial displacement of the core in the first cylindrical body due to vibration, etc. It has the effect of preventing the decrease. In the invention according to claim 2, in the invention according to claim 1, a frame member is attached to either one of the first case or the second case, and the frame member is attached to both of the cases. Since the case is provided with the attaching portion for attaching to the attached portion, in addition to the effect of the invention according to claim 1, when the displacement sensor is attached to the attached portion via the attaching portion of the case,
This has the effect that the positional relationship accuracy between the coil provided on the frame member and the core provided on the actuation body can be improved.

According to a third aspect of the present invention, in the first aspect of the present invention, an attaching portion for attaching to the attached portion is provided in the first case, and the attaching portion is parallel to the moving direction of the operating body. In addition to the effect of the invention of claim 1, the mounting hole for mounting the frame member is formed so as to be coaxial with the mounting hole. Since the part forming the mounting hole to which the mounting part and the frame member are mounted can be the same part, it is possible to prevent distortion of the case due to the formation of the mounting hole.

[Brief description of drawings]

FIG. 1 is a plan view of a displacement sensor according to an embodiment of the present invention.

FIG. 2 is a side view of the displacement sensor according to the above embodiment (see FIG.
A side view seen from the arrow Y direction in FIG.

FIG. 3 is a sectional view of the displacement sensor according to the above-described embodiment (see FIG.
XX cross section).

FIG. 4 is a circuit diagram of the torque detector.

[Explanation of symbols]

1 displacement sensor 10 First case 15 First guide hole 18 storage room 20 Second case 27 Spring support 30 frame members 35 Second guide hole 40 coils 50 actuator 52 First cylinder (part of actuator) 53 collar part 54 Action surface of actuator 56 Second cylinder (part of actuator) 58 cores (part of actuator) 60 coil spring

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/30

Claims (3)

(57) [Claims] 1. An actuating body having a core and a coil, wherein an oscillation frequency changing by an inductance of the coil changing by the core moving with the movement of the actuating body and a capacitor connected to the coil is detected. In the displacement sensor that detects the amount of displacement, the displacement sensor is configured such that a storage chamber is formed inside by a bottom wall formed with a first guide hole and a peripheral wall formed integrally with the outer peripheral portion, and one end side is an opening. A first case formed in the shape of a box with a bottom, and a spring support portion corresponding to the first guide hole and provided on the opening side of the first case and attached to the first case were provided. A second case, a frame member that has a second guide hole having the same diameter as the guide hole, and is disposed in the storage chamber with its axis aligned with the first guide hole; A coil provided on the frame member located on the outer circumference of the second guide hole, and formed into a bottomed cylindrical shape with one end side opening and the other end side acting as a working surface, and a flange portion on the outer circumference of the opening edge. A first cylindrical body in which the working surface projects a predetermined length from the first guide hole when the collar portion is brought into contact with the hole edge surface of the second guide hole, and the bottom wall of the first cylindrical body A core housed in the first cylindrical body by abutting one end side thereof, a spring receiving flange abutting the collar portion at one end side, and an end face on the other end side abutting on the other end face of the core An actuating body comprising a second cylindrical body fitted into the first cylindrical body and provided in the first cylindrical body,
It is arranged between the spring support portion of the second case and the hole edge surface of the second guide hole of the frame member, and urges the actuation body so that the working surface projects from the first guide hole. A displacement sensor comprising a coil spring. 2. The invention according to claim 1, wherein a frame member is attached to either one of the first case and the second case, and the attached portion is attached to the case to which the frame member is attached. Displacement sensor, characterized in that it is provided with a mounting portion for mounting on the. 3. The invention according to claim 1, wherein the first case is provided with a mounting portion for mounting to the mounted portion, and the mounting portion is formed by a mounting hole having an axial center parallel to the moving direction of the operating body. A displacement sensor which is configured and has an attachment hole for attaching the frame member coaxially with the attachment hole.