JP3421543B2 - Torque detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for detecting a torque acting on a drive shaft that transmits a driving force to an output side.

[0002]

2. Description of the Related Art Conventionally, when it is necessary to detect the torque of a transmission shaft that transmits a rotational force, a sensor is directly attached to the transmission shaft and the measured value of the sensor is taken out via a slip ring and a brush.

For example, in recent years, when an electric motor is connected to a drive system of a bicycle as an auxiliary power and the load at the time of pedaling becomes large, the driving force is assisted by the electric motor with an output according to the load, and the stepping load is increased. A bicycle with auxiliary power is used to reduce power consumption.

In this auxiliary power-assisted bicycle, it is known that the load when the pedal is depressed measures the torque acting on the drive shaft transmitting the power, and the output of the electric motor is controlled according to the measured value. is doing.

As a method of measuring the torque acting on the drive shaft, Japanese Patent Laid-Open No. 4-321482 discloses that a torsion bar (96) is used as the drive shaft as shown in FIG. 7, and the torsion bar (96) is distorted. A method is disclosed in which a gauge (97) is attached and the torque is measured from the amount of torsional strain. The measured torsional strain amount is taken out by a torsion bar (96) and a slip ring (98) and a brush (99) attached to a casing supporting the torsion bar (96), respectively.

However, in such a conventional measuring method, noise is mixed in the measured value due to wear of the slip ring (98) and the brush (99) or deterioration of the contact state, and an accurate measured value can be obtained. There wasn't.

On the other hand, the torsion bar (96) and strain gauge (97)
When using the gear mechanism consisting of multiple gears to measure the torque acting on the drive shaft without using the, avoid noise due to wear of the slip ring (98) or brush (99) or deterioration of contact condition. However, depending on the structure of the gear mechanism, there is a possibility that rattling may occur due to the gap between the gears.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and measures the torque of the power transmitted from the power source to the output side via the drive shaft using a gear mechanism. By doing so, the torque can be accurately measured without being affected by noise and the like, and by urging the gears that mesh with each other, there is provided a torque detection device in which rattling does not occur between the gears. is there.

[0009]

A torque detecting device of the present invention is a torque detecting device pivotally supported by a frame (70) and provided on a drive shaft for transmitting a driving force, which is integrally rotatable with the drive shaft. And a first rotating body (2) having a first spur tooth portion (22) having spur teeth formed on the outer periphery thereof, and the first rotating body (2) being integrally rotatable via an elastic body And a second rotary body having a second spur tooth portion (26) having spur teeth formed on the outer periphery thereof
(20) and the first driven gear (41) meshing with the first rotating body (2)
A second driven gear (43) meshing with the second rotating body (20), a swing gear (47) meshing with the first driven gear (41) and the second driven gear (43), and a first driven gear. A first link (51) that connects the gear (41) and the oscillating gear (47) in a meshed state, and a second driven gear (43)
And the second link that connects the rocking gear (47) in a meshed state
(52) and a fixing means for fixing either the first driven gear (41) or the second driven gear (43) to the frame (70), and the first
Orbital holding means for keeping the other rotating shaft of the driven gear (41) or the second driven gear (43) and the drive shaft at a constant distance, and detecting the displacement amount of the first link (51) and the second link (52) And a biasing means for biasing the first driven gear (41) and the second driven gear (43) toward or away from each other.

In such a structure, when a driving force acts on the drive shaft, a phase shift is generated between the first rotating body (2) and the second rotating body (20) against the elastic body. The first driven gear (41) and the oscillating gear (47) move in accordance with the deviation of the distance, and the angle formed by the first link (51) and the second link (52) that connect them to each other changes. The torque acting on the drive shaft can be detected by detecting the change in the angle by the detection means such as the potentiometer (6). Furthermore,
By biasing the first driven gear (41) and the second driven gear (43) by the biasing means, the gap between the gears is made substantially constant,
Since the error generated from the gap between the gears at the time of starting is suppressed, the torque can be accurately detected.

The first rotating body (2) is provided with a disk portion (21) having a circular outer periphery, and the first spur tooth portion (22) is provided with the disk portion (21).
The second rotating body (20) has a circular opening.
(25), and the disc portion of the first rotating body (2) is provided in the opening (25)
(21) is loosely fitted.

With this structure, the chain wheel (7) having the first rotating body (2) and the second rotating body (20) is provided.
5) can be made thin. Also, the first rotating body
If the number of teeth of (2) and the second rotating body (20) are different,
The second driven gear (43) is a two-stage gear including a first gear portion (45) that meshes with the second rotating body (20) and a second gear portion (46) that meshes with the swing gear (47). And the gear ratio eliminates the phase difference between the first rotating body (2) and the second rotating body (20). Specifically, the ratio of the number of teeth of the second gear portion (46) to the number of teeth of the first gear portion (45) is such that the number of teeth of the first spur tooth portion (22) and the number of second spur tooth portion (26). It should be equal to the ratio of the number of teeth.

Further, as a fixing means, a second driven gear (43)
By using the fixed link (54) that connects the second rotary body (20) and the second rotary body (20) in a meshed state, any part of the fixed link (54) is fixed to the frame (70), and thus the second driven gear ( 43) can be fixed to the frame (70).

The first driven gear is used as the track holding means.
By using the orbit holding link (53) that connects the (41) and the first rotating body (2) in a meshed state, the first driven gear (41)
It is possible to stabilize the meshing state between the first rotating body (2) and the first rotating body (2).

Further, by using an elastic member whose one end is locked to the track holding means and the other end is locked to the shaft support means as the urging means, the first driven gear (41) and the second driven gear (41) (Four
3) can be urged toward or away.

On the other hand, as a drive shaft, a crank shaft (which is connected to a pedal mechanism (74) to which pedal force is applied and which transmits pedal force to a chain wheel (75) which meshes with a chain (77) which drives a rear wheel (92). The torque detecting device (1) can be mounted on a bicycle by integrally attaching the second rotating body (2) to the chain wheel (75) by using the (10). In this case, the first driven gear (41) and the second driven gear (4
3) By biasing the gaps, the gap between the gears is made substantially constant at the beginning of rowing, and the error caused by the gap between the gears at the beginning of rowing is suppressed. Further, even if the bicycle is stopped while the vehicle is running, rattling between the gears due to vibrations received from the road surface does not occur, so that the torque can be accurately detected.

When a bicycle with auxiliary power for assisting the power of the rear wheels based on the detection value of the electric motor (8) is used as the bicycle, the torque can be accurately detected. The electric motor (8) can be finely controlled.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment in which the torque detection device of the present invention is applied to a bicycle with auxiliary power will be described below.

FIG. 1 is a side view showing the construction of an auxiliary power-equipped bicycle equipped with the torque detection device of the present invention. In the following description, the bicycle with auxiliary power (7) indicated by arrow F in the figure
The forward direction is the forward direction, and the backward direction indicated by the arrow R is the backward direction.

As shown in the figure, a bicycle with auxiliary power (7)
The handle (71) and the handle (7
The front wheel (91) is provided which changes its direction according to the steering angle of 1). The seat tube (72) at the center of the frame (70) has the seat (73) attached to the upper part thereof, and the pedal device (74) provided with the chain wheel (75) described below is arranged at the lower part thereof. . A cover (56) accommodating a torque detection device (1) described later is provided from the center part of the chain wheel (75) to the upper part thereof. A free wheel (76) connected to the rear wheel (92) is provided at the rear of the frame (70), and an endless chain (77) is provided between the free wheel (76) and the chain wheel (75). ) Is stretched.

The electric motor (8) provided outside the free wheel (76) is meshed with the chain (77) via a reduction mechanism and a one-way clutch (not shown). The electric motor (8) is electrically connected to the power feeding mechanism (84) attached to the seat tube (72) and output by the control unit (80) electrically connected to the power feeding mechanism (84). Control is performed.

As shown in FIG. 2, the pedal device (74) includes a crankshaft (10) pivotally supported on a lower portion of the seat tube (72),
A crank arm (11) standing upright from both ends of the crank shaft (10) and a crank pin (1) protruding from the tip of the crank arm (11) in a direction substantially parallel to the crank shaft (10).
2) and a pedal (13) rotatably attached to the crank pin (12). Also, on the crankshaft (10),
First rotating body that rotates integrally with the chain wheel (75)
(2) is fitted.

As shown in FIGS. 2 and 3, the torque detecting device (1) includes a chain wheel (75) that rotates integrally with the crankshaft (10) and a gear mechanism (4) provided around the chain wheel (75).
A link mechanism (5) for connecting them, a biasing means (9) for biasing the driven gears (41, 43) of the gear mechanism (4) toward or away from each other, and a link mechanism (5 ) Attached to the potentiometer (6). The chain wheel (75) is integrally attached to the second rotating body (20) and is connected to the first rotating body (2) fitted to the crankshaft (10) via an elastic body. .

The first rotating body (2) has a disk portion (21) having a circular outer periphery, and a first annular member protruding from the disk portion (21) in an annular shape and having spur teeth formed along the outer periphery. The crankshaft (10) is fitted in the center of the crankshaft (10). Disk part (21)
Two notches (24) are formed on the outer circumference of the projecting piece for attaching the compression spring (3) to each of the notches (24).
(23a) is formed.

The second rotating body (20) is provided with a circular opening (25) at the center thereof, and the disk (2) of the first rotating body (2) is provided in the opening (25).
1) is loosely fitted. Further, the second rotating body (20), second spur portion provided with a (26), chain wheel (75) is integrally attached to the chain (77) meshes with the spur teeth along the outer periphery is formed Has been. Furthermore, on the inner circumference of the second rotating body (20),
Protrusions (23) protruding from each notch (24) of the first rotating body (2)
A protrusion (23b) is formed so as to face (a), and both protrusions (23a)
A compression spring (3) is stretched between (23b).

By this compression spring (3), the first rotating body (2)
Also, the second rotating body (20) is integrally rotatably connected. The compression spring (3) has a first rotating body (2) and a second rotating body (20) when torque applied to the crankshaft (10) exceeds a predetermined threshold value.
It has a spring constant such that a rotation deviation occurs between them.
Although the compression spring (3) is used as the elastic body, it is not limited thereto.

Further, the second spur tooth portion (26) has a second driven gear.
(43) is in mesh. The second driven gear (43) is the second rotating body.
A first gear portion (45) meshing with the second spur tooth portion (26) of (20) and a second gear portion (45) protruding from the first gear portion (45) and meshing with a swing gear (47) described later. It is composed of a two-stage gear portion including a gear portion (46). The rotation shaft (44) of the second driven gear (43) is pivotally supported by the fixed link (54). One end of the fixed link (54) is pivotally supported by the crankshaft (10), and the other end is seat tube (72).
It is fixed to. Although the linear fixed link (53) is used as the shaft support means, various shapes can be adopted depending on the shape of the frame (70) and the mounting position. Further, the rotary shaft (44) of the second driven gear (43) can be pivotally supported by the cover (56) or the seat tube (72).

The swing gear (47) is meshed with the first driven gear (41) and the second gear portion (46) of the second driven gear (43). The rotation shaft (48) of the rocking gear (47) is the rotation shaft of the first driven gear (41).
(42) is connected to the first link (51) and is connected to the rotation shaft (44) of the second driven gear (43) by the second link (52).
It is possible to swing while maintaining a state parallel to the crankshaft (10).

The rotation shaft (42) of the first driven gear (41) is
It is pivotally supported at one end of the track holding link (53). The other end of the track holding link (53) is concentric with the crankshaft (10) in a state where the first driven gear (41) meshes with the first spur tooth portion (22) of the first rotating body (2). Is pivoted to. Although the track holding link (53) is used as the track holding means, an elastic body such as a spring can be used.

The first link (51) and the second link (52) are formed such that the lengths between the respective pivotal support portions are equal, and the crankshaft (10)
When there is no load applied to the first rotating body (2) and the second rotating body (20), the first link (51) and the second link (52) Are set so as to form an angle of approximately 90 degrees as shown in FIG.

A spring (9) is stretched between the first link (51) and the second link (52), and the spring (9) causes the first driven gear (41) and the second driven gear (41) to move. The driven gear (43) is urged in the approaching direction. At this time, for example, as shown in FIG. 5, the meshing portion between the first driven gear (41) and the swing gear (47) has the spur teeth (41a) of the first driven gear (41) attached in the arrow direction. Energized, rocking gear
It is pressed against the flat tooth (47a) of (47).
Similarly to this, the first spur tooth portion (22) of the first rotating body (2) and the first
The meshing part with the driven gear (41), the swing gear (47) and the second driven gear
(43) meshing part with the second gear part (46), the first gear part (45) of the second driven gear (43) and the second spur tooth part (26) of the second rotating body (20). The meshing part is also in a state where one spur tooth is pressed against the other spur tooth. Since the spur teeth meshing with each other are biased in this way, there is no rattling between the gears and stability is achieved even when no load is applied.

In this embodiment, as the urging means,
A spring (9) was used, but is not limited to it. Further, even if the first driven gear (41) and the second driven gear (43) are biased in the separating direction, the same effect can be obtained by only reversing the biasing directions.

An example of the number of teeth of the rotating bodies (2) and (20) and the gear mechanism (4) of the above torque detecting device (1) will be shown below.

[0034]

[Table 1]

The potentiometer (6) is provided above the rotation shaft (48) of the swing gear (47) at a position independent of the rotation of the rotation shaft (48), and the measurement arms (61) (61). Each is the first link
It is locked to (51) and the second link (52). Thereby, the angles of the first link (51) and the second link (52) are detected as the angle of the measuring arms (61) (61), that is, the resistance value of the potentiometer (6).

The potentiometer (6) is electrically connected to a control unit (80) for controlling the output of the electric motor (8), and the control unit (80), as shown in FIG. 6, is a central processing unit. (C
PU) (81). The CPU (81) has a memory (82) storing various data including the relationship between the measured value of the potentiometer (6) and the current value applied to the electric motor (8) corresponding to the measured value, and a memory (82) described later. Comparing arithmetic circuit (83)
And the drive control circuit (85) connected to the power supply mechanism (84).

The result measured by the potentiometer (6) is passed through the amplification circuit (86) and the A / D conversion circuit (87).
It is sent to the comparison operation circuit (83) as a digital value. The comparison operation circuit (83) compares the measured value of the potentiometer (6) with the data stored in the memory (82) and
The current value applied to (8) is determined and transmitted to the drive control circuit (85).

The drive control circuit (85) controls the power feeding mechanism (84) so as to supply the electric motor (8) with a current corresponding to the current value sent from the comparison operation circuit (83). In this embodiment, the power supply command from the drive control circuit (85) is the crankshaft.
The torque acting on (10) is a predetermined value, that is, the first link (51)
And it is assumed that the signal is transmitted only when the angle formed by the second link (52) exceeds a predetermined threshold value.

The operation of the bicycle (7) with auxiliary power equipped with the above-mentioned torque detection device (1) will be described below.
When the user does not depress the pedal (13), or when the torque generated on the crankshaft (10) is smaller than the urging force of the compression spring (3) even when the user depresses the pedal (13), as shown in FIG. As shown in, the first link (51) and the second link
(52) forms an angle of about 90 degrees. Hereinafter, this state will be referred to as a reference state.

A large driving force is required to drive the bicycle (7) at the start of rowing of the bicycle (7), at the time of acceleration, or on an uphill, and when the pedal (13) is depressed, the crankshaft (10) becomes large. Torque acts. When torque is applied to the crankshaft (10), as shown in FIG. 4, it is rotated between the first rotating body (2) and the second rotating body (20) against the restoring force of the compression spring (3). A shift occurs, and the phase of the first rotating body (2) leads the phase of the second rotating body (20). Along with this, the first driven gear (41)
The rotation speed of is greater than the rotation speed of the second driven gear (43),
The first driven gear (41) is the first spur tooth portion (22) of the first rotating body (2).
Move in the direction of arrow A while meshing with. Like this first
When the driven gear (41) moves, the second driven gear (43) is pivotally supported by the seat tube (72) via the fixed link (54), so that the distance between the gears (41) and (43) is reduced. growing. That is, the angle formed by the first link (51) and the second link (52) is expanded. Due to this angle change, the resistance value of the potentiometer (6) changes, and the value is sent to the control unit (80).

The resistance value sent from the potentiometer (6) to the control unit (80) is amplified and A / D converted, and then compared with the data stored in the memory (82) by the comparison operation circuit (83). If the resistance value is equal to or higher than the threshold value, the current value corresponding to the value is calculated as the current value supplied to the electric motor (8). The calculated current value is sent to the drive control circuit (85), and a current based on the current value is supplied from the power supply mechanism (84) to the electric motor (8). As a result, the electric motor (8) drives the chain (77) to assist the traveling of the bicycle (7).

When the electric motor (8) assists the traveling of the bicycle (7), the load required on the pedal system (74) is reduced. When the torque acting on the crankshaft (10) becomes small, the restoring force of the compression spring (3) reduces the deviation between the first rotating body (2) and the second rotating body (20), and approaches the reference state. Then, when the resistance value of the potentiometer (6) becomes smaller than the threshold value, the power feeding from the power feeding mechanism (84) to the electric motor (8) is stopped. When torque is applied to the chain wheel (75) again, the above-mentioned operation is repeated and the electric motor
The drive of the bicycle (7) is assisted by (8).

In the above-described embodiment, the case where the torque detecting device of the present invention is applied to the bicycle with auxiliary power has been described, but the present invention is not limited to this and can be applied to an electric screwdriver, an electric drill, or the like. .

Further, in the above embodiment, since the number of teeth of the first spur tooth portion of the first rotating body is different from that of the second spur tooth portion of the second rotating body, the second driven gear is the two-stage gear. However, when the number of teeth of the first spur tooth portion is equal to that of the second spur tooth portion, one step may be used as in the first driven gear.

[0045]

According to the torque detecting device of the present invention, the use of the gear mechanism eliminates the need for a slip ring, a brush or the like for taking out the measurement result, and can eliminate the influence of noise due to wear and the like. By always urging the first driven gear and the second driven gear in the approaching or separating directions, it is possible to eliminate rattling between the gears meshing with each other, and therefore accurate torque measurement can be performed.

Furthermore, when the torque detection device of the present invention is mounted on a bicycle, it can be easily carried out by simply replacing it with a chain wheel of an existing bicycle, and it is not necessary to make a large design modification.

[Brief description of drawings]

FIG. 1 is a side view of an auxiliary power-equipped bicycle equipped with the torque detection device of the present invention.

FIG. 2 is a perspective view of a torque detection device of the present invention.

3 is a cross-sectional view taken along the line YY 'of the torque detection device of FIG.

FIG. 4 is a cross-sectional view showing a state where torque acts on the torque detection device of FIG.

5 is an enlarged cross-sectional view in which a meshing portion between a first driven gear and a swing gear of the torque detection device in FIG. 2 is enlarged.

FIG. 6 is a circuit block diagram of a control unit of the bicycle with auxiliary power of FIG. 1.

FIG. 7 is a perspective view showing a conventional torque detection device.

[Explanation of symbols]

9: Spring 54: fixed link 52: Second link 51: First link 43: Second driven gear 20: Second rotating body 47: Swing gear 41: 1st driven gear 10: Crankshaft 1: Torque detection device 22: First flat tooth portion 2: First rotating body 3: Compression spring 26: Second flat tooth portion 20: Second rotating body 6: Potentiometer

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01L 3/14 B62M 23/02

Claims (9)

(57) [Claims] 1. A torque detection device pivotally supported by a frame (70) and provided on a drive shaft for transmitting a driving force, wherein the torque detection device is integrally rotatably connected to the drive shaft and has spur teeth formed on an outer periphery thereof. First rotating body (2) having a first spur tooth portion (22)
And a second rotary body (20) having a second spur tooth portion (26), which is integrally rotatably connected to the first rotary body (2) via an elastic body and has spur teeth formed on the outer periphery, A first driven gear (41) meshing with the first rotating body (2), a second driven gear (43) meshing with the second rotating body (20), the first driven gear (41) and the Second
A swinging gear (47) meshing with the driven gear (43), a first link (51) that connects the first driven gear (41) and the swinging gear (47) in a meshed state, and the second A second link (52) that connects the driven gear (43) and the swing gear (47) in a meshed state
And the first driven gear (41) or the second driven gear (43)
Fixing means for fixing either one of them to the frame (70), and the first driven gear (41) or the second driven gear (43)
Orbit holding means for keeping the other rotary shaft and the drive shaft at a constant distance, and the first link (51) and the second link (52).
Detecting means for detecting the amount of displacement of the first driven gear (41)
And a biasing means for biasing the second driven gear (43) toward or away from the second driven gear (43). 2. The first rotating body (2) is provided with a disc portion (21) having a circular outer periphery, and the first spur tooth portion (22) is projected from the disc portion (21). The second rotating body (20) is a disc portion (2) of the first rotating body (2).
2. The torque detection device according to claim 1, wherein 1) is provided with a circular opening (25) that is rotatably loosely fitted. 3. The second driven gear (43) includes a first gear portion (45) meshing with the second rotating body (20), and the swing gear (47).
A second gear portion (46) meshing with the second gear portion (46), and the ratio of the number of teeth of the second gear portion (46) to the number of teeth of the first gear portion (45) is such that the first spur tooth portion (22) Number of teeth and the second flat tooth (2
The torque detection device according to claim 1 or 2, wherein the ratio is equal to the ratio of the number of teeth in 6). 4. The fixing means includes the second driven gear (43).
And a fixed link ( 54 ) which is connected to the second rotating body (20) in a meshed state and is fixed to the frame (70).
The torque detection device according to any one of claims 1 to 3, wherein the torque detection device comprises: 5. The track holding means is the first driven gear.
The track holding link (53), which connects the (41) and the first rotating body (2) in a meshed state with each other,
5. The torque detection device according to any one of 4 to 4. 6. The urging means comprises an elastic member having one end locked to the track holding means and the other end locked to the shaft support means. The torque detection device according to claim 1. 7. The detecting means comprises a potentiometer (6) for detecting an angle formed by the first link (51) and the second link (52), according to any one of claims 1 to 6. The described torque detection device. 8. The drive shaft is connected to a pedal mechanism (74) of a bicycle to which pedal force is applied, and transmits the pedal force to a chain wheel (75) that meshes with a chain (77) that drives a rear wheel (92). The torque detection device according to any one of claims 1 to 7, wherein the torque detection device is a crankshaft (10), and the second rotating body (2) is integrally attached to the chain wheel (75). apparatus. 9. The torque detecting device according to claim 8, wherein the bicycle is an assisted-powered bicycle that assists powering of rear wheels based on a detection value of the detecting means by an electric motor (8). .