JPH08178769A - Rotary torque detector - Google Patents

Abstract

PURPOSE: To provide the inexpensive rotary torque detector with the simple structure, which does not require zero adjustment and can detect the torque highly accurately. CONSTITUTION: The phase difference between a driving shaft (first rotary shaft) linked by a torsion bar (torque transmission shaft), which converts the torque into the torsion angle, and a resultant-force shaft (second rotary shaft) is detected. Thus, the torque, which is inputted into the driving shaft, is detected by a rotary potentiometer (rotary-type torque detector) 30. The rotary potentiometer 30 is constituted by including brushes 55 and 58, which are attached to the driving shaft and the resultant force shaft, respectively, and resistors 52 and 57, on which the respective brushes 55 and 58 slide in contact. When, for example, a constant current is made to flow through the respective resistors 52 and 57, the resistors 52 and 57 act as variable resistors. The resistance values are linearly changed depending on the contact positions of the brushes 55 and 58. Therefore, the phase difference corresponding to the torsion angle of the driving shaft and the resultant-force shaft is generated in the voltages outputted from the resistors 52 and 57. Therefore, the torque is detected highly accurately by detecting the phase difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary torque detecting device for detecting a torque input to a first rotary shaft by detecting a phase difference between the first rotary shaft and the second rotary shaft.

[0002]

2. Description of the Related Art As an auxiliary power type vehicle, a bicycle with an electric motor has been proposed, which is used for supplementing the driving force by human power with the auxiliary power by an electric motor. This bicycle with an electric motor is provided with a drive system based on an electric motor in addition to a drive system based on human power, and reduces physical load on the rider by detecting human power and applying auxiliary power corresponding to the magnitude to the wheels. It is a thing.

By the way, in such a bicycle with an electric motor, human power (torque) input to a crank shaft (human power input shaft) is used.
However, the following method has been adopted to detect this human power.

That is, a crankshaft and a resultant shaft (a shaft for combining human power and auxiliary power) are coaxially arranged, and a torque detection shaft is arranged in parallel with them, and a planetary gear mechanism is used for power transmission from the crankshaft to the resultant shaft. By using the, the reaction force generated in the sun gear by the human power input to the crankshaft is transmitted to the torque detection shaft via a cam mechanism, and the human power is detected by detecting the operating angle of the torque detection shaft with a rotary potentiometer or the like. Was.

[0005]

However, in the above-mentioned conventional torque detection method, there is a problem that the number of parts increases due to the long reaction force transmission path, resulting in an increase in the number of assembly steps and an increase in cost. It was

Further, there is a problem that torque detection accuracy is deteriorated due to accumulation of dimensional tolerances of many components and large friction generated in the cam contact portion, and troublesome zero point adjustment is required.

The present invention has been made in view of the above problems, and an object thereof is to provide a rotary torque detecting device having a simple structure and a low cost that does not require zero-point adjustment and can detect torque with high accuracy. To provide.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 has a first rotating shaft and a second rotating shaft connected by a torque transmission shaft for converting a torque into a torsion angle. And a brush attached to each of the first rotating shaft and the second rotating shaft, and a rotary torque detecting device for detecting torque input to the first rotating shaft by detecting a phase difference between It is characterized in that each of the brushes includes a ring-shaped resistor to be brought into sliding contact.

According to a second aspect of the present invention, in the first aspect of the invention, the first rotating shaft, the second rotating shaft, and the torque transmitting shaft are coaxially arranged, and the resistor is provided in plural. It is characterized by being divided into equal parts.

Further, the invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the both resistors are integrally formed.

[0011]

According to the first aspect of the invention, the torque input to the first rotary shaft is transmitted to the second rotary shaft via the torque transmission shaft, but the twist angle of the torque transmission shaft is the torque. In proportion to the magnitude, this twist is transmitted to the second rotary shaft, so that a phase difference of the twist angle proportional to the magnitude of the torque is generated in both rotary shafts.

If, for example, a constant current is applied to each resistor, each resistor acts as a variable resistor and its resistance value changes linearly depending on the contact position of the brush, so that each resistor outputs it. Voltage changes periodically with a predetermined phase due to the rotation of the first and second rotary shafts, and the voltage change output from each resistor has a phase difference corresponding to the phase difference of the twist angles of both rotary shafts. When this occurs and the phase difference is detected, the torque input to the first shaft can be obtained.

Since the torque detecting device is simply structured by the brushes attached to the respective rotating shafts and the resistors to which the respective brushes should be slidably contacted, the number of parts is reduced, and the size and cost are reduced. In addition to downsizing, it is possible to obtain high torque detection accuracy by preventing the accumulation of dimensional tolerances of parts and the occurrence of large friction.
Further, since the resistor is formed in the ring shape, the torque can be continuously detected, and the zero-point adjustment which has been required in the past is not necessary, so that the torque can always be detected with high accuracy.

According to the second aspect of the present invention, the first rotary shaft, the second rotary shaft, and the torque transmission shaft are coaxially arranged, so that the torque detecting device can be made more compact. The resolution of torque detection can be arbitrarily changed by changing the number of divisions of the resistor.

According to the third aspect of the present invention, since both resistors are integrally formed, the mounting accuracy thereof can be improved and the torque can be detected with high accuracy.

[0016]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side view of an electric motor vehicle equipped with a rotary torque detecting device according to the present invention, FIG. 2 is a plan sectional view of a power unit portion of the same electric motor bicycle, and FIG. 3 is a rotary type according to the present invention. FIG. 4 is an enlarged cross-sectional view of the torque detection device, FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3, and FIG. 5 is a voltage characteristic diagram with respect to the rotation angle of the rotation shaft.

First, a schematic structure of the bicycle 1 with an electric motor will be described with reference to FIG.

In FIG. 1, reference numeral 2 is a head pipe located in front of the vehicle body, and a handle stem 3 is rotatably inserted in the head pipe 2. A handle 4 is attached to the upper end of the handle stem 3, and a front fork 5 is attached to the lower end of the handle stem 3, and a front wheel 6 is rotatably attached to the lower end of the front fork 5. It is supported.

The head pipe 2 is connected to the front end of a main frame 7 which is bent in a substantially U shape, and a portion which doubles as a seat pipe is provided at an upper portion of the main frame 7 at an angle. The seat 9 is supported via the seat post 8. The battery 10 is supported on the straight portion of the front half of the main frame 7.

By the way, a power unit 11 is supported by the main frame 7 via brackets 12 and 13 at the lower center of the vehicle body. This power unit 11
Is configured by arranging a drive system by human power and a drive system by an electric motor in parallel, and a crankshaft 14 is rotatably supported by the crankshaft 14, and cranks 15 are attached to the left and right ends of the crankshaft 14, respectively. A pedal 16 is pivotally supported at the end of the crank 15.

A pair of left and right chain stays 17 extend rearward of the vehicle body from the power unit 11. The rear end of the chain stay 17 and the main frame 7 are connected by a pair of left and right seat stays 18. Has been done. A rear wheel 19 is rotatably supported at a connecting portion of the rear end of the chain stay 17 with the seat stay 18, and a wheel sprocket 20 is attached to an axle supporting the rear wheel 19.

The details of the structure of the power unit 11 will be described with reference to FIG.

In the power unit 11 shown in FIG.
The crankshaft 14 is attached to the case 21 divided into two parts on the left and right
Is rotatably supported by bearings 22 and 23, and behind the crankshaft 14, a hollow drive shaft 24 and a resultant shaft 25, which are divided into left and right and are coaxially arranged in the lateral direction, are bearer rings 26 ,. Each of them is rotatably supported by 27. The drive shaft 24 and the resultant shaft 25 are rotatable relative to each other, and one end of the resultant shaft 25 is fitted to the outer periphery of the end of the drive shaft 24 through a limiter 28 so that the drive shaft 24 and the resultant shaft 25 can rotate relative to each other. . And
Inside of these drive shaft 24 and resultant shaft 25 (hollow part)
A torsion bar 29 is inserted into the drive shaft 24. One end of the torsion bar 29 is attached to the outer end of the drive shaft 24 by pin coupling, and the other end of the torsion bar 29 is also connected to the outer end of the resultant shaft 25. It is attached by pin connection.

By the way, the drive shaft 24 and the resultant shaft 2
A rotary potentiometer 30 constituting the rotary torque detection device according to the present invention is provided on the rotary shaft 5, and the rotary potentiometer 30 includes an input potentiometer 30A provided on the drive shaft 24 side and a resultant shaft 25. The output potentiometer 30B is provided on the side.

A small-diameter speed increasing gear 31 is joined to the outer circumference of the outer end of the drive shaft 24 by serration coupling. The speed increasing gear 31 is a one-way clutch on the outer circumference of one end of the crankshaft 14. It meshes with a large-diameter internal gear speed-up gear 33 supported via 32. Also, the resultant shaft 25
A large-diameter speed-increasing gear 35 is provided on the outer periphery of the intermediate portion of the drive shaft 25 via a one-way clutch 34, and a drive sprocket 36 is connected to the outer periphery of the end of the joint shaft 25 extending outside the case 21 by screwing. It is worn. An endless chain 37 is wound around the drive sprocket 36 and the wheel sprocket 20 shown in FIG.

On the other hand, an electric motor 38 is laterally attached to the case 21, and a reduction gear 40 having a small diameter is formed at one end of a motor shaft 39 of the electric motor 38. The reduction gear 40 meshes with an idle gear 41. The idle gear 41 has a large diameter and is connected by serration coupling to one end of a reduction shaft 43 rotatably supported by a bearing 42 in the case 21. It meshes with the reduction gear 44. A reduction gear 45 having a small diameter is integrally formed at the other end of the reduction shaft 43, and the reduction gear 45 meshes with the reduction gear 35.

By the way, in this embodiment, the case 2 is used.
1 inside the speed-increasing gear 33 and inside the space defined around the crankshaft 14, the battery 1
A controller 60 for controlling the supply voltage (or current) from 0 to the electric motor 38 is housed.

The configuration of the rotary potentiometer 30 according to the present invention will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, the housing 46 of the rotary potentiometer 30 accommodates a flange 47 connected to the outer periphery of the drive shaft 24 and a flange 48 connected to the outer periphery of the resultant shaft 25. And two discs 4 between the flanges 47 and 48 in the housing 46.
9,50 are fixed.

As shown in FIG. 4, an inner and outer double ring-shaped conductor 51 and a resistor 52 are attached to the surface of the disk 49 facing the flange 47, and the conductor 51 is a lead wire 53. It is connected to the battery 10 via. Further, the resistor 52 is divided into four equal parts, and both ends of each divided piece 52a are connected to the battery 10 by the lead wires 54, and the portions divided by the resistor 52 and having the same potential are respectively divided. It is connected by a conductor 70.
The tip of a forked brush 55 attached to the flange 47 is in contact with the conductor 51 and the resistor 52, and the brush 55, the conductor 51, the resistor 52, etc. are connected to the input potentiometer 30A. Are configured.

Similarly, the flange 48 of the disk 50 is
On the surface opposite to the conductor 56, which is exactly the same as the conductor 51.
And a resistor 57 that is exactly the same as the resistor 52 (composed of divided pieces 57a divided into four equal parts) is attached, and a conductor 56 is connected to the battery 10 via a lead wire 53. Both ends of each divided piece 57a are connected to the battery 10 via lead wires 54 (see FIG. 3). The tip of a forked brush 58 attached to the flange 48 is in contact with the conductor 56 and the resistor 57. The brush 58, the conductor 56, and the resistor 5
7 and the like constitute the output side potentiometer 30B. Both resistors 52 and 57 are attached at the same angular position.

Next, the operation of the bicycle 1 with an electric motor will be described.

When the rider alternately depresses the left and right pedals 16 to drive the crankshaft 14 to rotate, the rotation of the crankshaft 14 is accelerated through the one-way clutch 32 and the speed increasing gears 33, 31 to drive the drive shaft 24 and the torsion bar. 29, and further transmitted from the torsion bar 29 to the resultant shaft 25. Therefore, the human power (torque) input to the crankshaft 14 is transmitted to the resultant shaft 25 via the torsion bar 29.

On the other hand, the rotation of the motor shaft 39 of the electric motor 38 is controlled by the reduction gear 40, the idle gear 41, and the reduction gear 4.
4, the reduction shaft 43, the reduction gears 45 and 35, and the one-way clutch 34 are decelerated and transmitted to the resultant shaft 25. Therefore, the auxiliary power generated by the electric motor 38 is transmitted to the resultant shaft 25 through the above path. It

The resultant shaft 25 is rotationally driven by both human power and auxiliary power, and its rotation is driven by the drive sprocket 36, the chain 37 and the wheel sprocket 20.
After being transmitted to the rear wheel 19, the rear wheel 19 is rotationally driven by both human power and auxiliary power, and the bicycle 1 with an electric motor is driven.

By the way, as described above, the human power input to the crankshaft 14 is transmitted through the torsion bar 29 to the resultant shaft 2.
5, the torsion bar 29 is twisted by an amount proportional to the magnitude of human power, and this twist causes a phase difference in the torsion angle between the drive shaft 24 and the resultant shaft 25. This phase difference is the rotational potentiometer. Detected by 30.

Here, the detection principle of the rotary potentiometer 30 will be described.

Input side potentiometer 30A and output side potentiometer 3 from battery 10 via lead wire 53.
If a constant current is applied to 0B, each potentiometer 30A, 3
At 0B, the current flows in each conductor 51, 56 and brush 55,
Flow through the resistors 52 and 57 via 58, respectively. At this time, each of the resistors 52 and 57 acts as a variable resistor, and the resistance value changes linearly depending on the contact position of each of the brushes 55 and 58, so that the voltage output from each of the divided pieces 52a and 57a is as shown in FIG. As shown in FIG. 5, for example, it changes along a linear straight line of 0 V to 5 V, and therefore, for one rotation of the drive shaft 24 and the resultant shaft 25, the change shown in FIG. Here, in a no-load state in which no human power is input to the crankshaft 14, and when there is no phase difference in the torsion angle between the drive shaft 24 and the resultant shaft 25,
The voltage changes in both potentiometers 30A and 30B are exactly the same, but when human power is input to the crankshaft 14 as described above, the torsion bar 29 is twisted and the phase difference in the torsion angle between the drive shaft 24 and the resultant shaft 25 is caused. As shown in FIG. 5, the potentiometers 30A, 3
The illustrated phase difference Δθ occurs in the voltage change at 0B, and since this phase difference Δθ is proportional to the magnitude of the human power (torque) input to the crankshaft 14, if this phase difference Δθ is detected, the human power (torque ) Can be obtained.

The phase difference Δθ is calculated by the controller 6
0, the controller 60 determines the magnitude of human power (torque) based on the phase difference Δθ, and controls the supply voltage (or current) from the battery 10 to the electric motor 38 according to the magnitude of human power. The auxiliary power generated by the electric motor 38 is adjusted to a predetermined value with respect to human power.

In the above, according to this embodiment, the rotary potentiometer 30 includes the brushes 55, 58 attached to the drive shaft 24 and the resultant shaft 25, and the brushes 55, 58, respectively.
Since 58 is simply structured by the resistors 52 and 57 to be in sliding contact with each other, the number of parts thereof is reduced, downsizing and cost reduction are achieved, and dimensional tolerances of parts are accumulated and large friction is generated. Is prevented, and the torque can be detected with high accuracy. Also, resistors 52, 5
Since 7 is formed in a ring shape, the torque can be continuously detected, and the zero-point adjustment, which has been required in the past, is not necessary, and the torque can be always detected with high accuracy.

Further, according to this embodiment, the drive shaft 2
4. Since the resultant shaft 25 and the torsion bar 29 are coaxially arranged, the rotary potentiometer 30 arranged around them can be made more compact. The resolution of torque detection can be arbitrarily changed by changing the number of divisions of the resistors 52 and 57.

Further, according to this embodiment, both resistors 52,
Since 57 is integrally formed in the common housing 46, its mounting accuracy is enhanced and highly accurate torque detection is possible.

In the above, an example in which the present invention is applied to the detection of human power in a bicycle with an electric motor has been described.
Needless to say, the application of the present invention is not limited to this.

[0045]

As is apparent from the above description, according to the present invention, the phase difference between the first rotating shaft and the second rotating shaft connected by the torque transmitting shaft for converting the torque into the torsion angle can be reduced. A rotary torque detection device that detects the torque input to the first rotation shaft by detecting the brush is attached to each of the first rotation shaft and the second rotation shaft, and each brush slides. Since the ring-shaped resistor to be brought into contact is included, the rotary torque detection device can be constructed with a simple structure and at low cost, and the torque can be detected with high accuracy without requiring zero-point adjustment. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a side view of an automobile with an electric motor including a rotary torque detection device according to the present invention.

FIG. 2 is a plan sectional view of a power unit portion of an automobile with an electric motor including a rotary torque detection device according to the present invention.

FIG. 3 is an enlarged cross-sectional view of a rotary torque detection device according to the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a voltage characteristic diagram with respect to a rotation angle of a rotating shaft.

[Explanation of symbols]

24 Drive Shaft (First Rotation Shaft) 25 Combined Shaft (Second Rotation Shaft) 29 Torsion Bar (Torque Transmission Shaft) 30 Rotation Potentiometer (Rotary Torque Detector) 30A Input Potentiometer 30B Output Potentiometer 52, 57 Resistance Body 55,58 brush

Claims (3)

[Claims] 1. A torque input to a first rotary shaft is detected by detecting a phase difference between a first rotary shaft and a second rotary shaft connected by a torque transmission shaft for converting torque into a torsion angle. A device for detecting, comprising: brushes attached to each of the first rotary shaft and the second rotary shaft; and ring-shaped resistors to which the respective brushes should slide. And a rotary torque detector. 2. The rotation according to claim 1, wherein the first rotation shaft, the second rotation shaft and the torque transmission shaft are coaxially arranged, and the resistor is divided into a plurality of equal parts. Torque detector. 3. The rotary torque detection device according to claim 1, wherein the both resistors are integrally formed.