JP2000038185A - Driving force transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving force transmission device, wherein reliability and safety are improved by preventing mechanical gear attaching/detaching when a gear train for transmitting the rotational force of a motor is switched. SOLUTION: During the forward rotation of a motor 21, the rotational force of the motor 21 is transmitted through gears 22 and 27 fixed to a rotary shaft 21a and a one-way clutch 29 to a gear 28, and a transmission gear 30 is rotated by the gear 28. On the other hand, during the backward rotation of the motor 21, the rotational force of the motor 21 is transmitted through a one-way clutch 25 to a gear 24, and the transmission gear 30 is rotated by the gear 24. Thus, gear trains are switched according to the forward/backward rotation of the motor 21, and no mechanical gear attaching/detaching is carried out at the time of gear switching. Thus, reliability and safety are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a driving force transmission device having two gear trains, and more particularly to a driving force transmission device that switches gear trains by forward and reverse rotation of a motor.

[0002]

2. Description of the Related Art By transmitting the torque of a motor to a rotating shaft of a foot pedal of a bicycle (hereinafter, simply referred to as a pedal), a rotating shaft of a rear wheel (drive wheel), or the like, the load on a vehicle during traveling is reduced. Assisted bicycles have been proposed to reduce the impact. Assisted bicycles control the power assisted by the motor (assist force) in response to changes in the force (human power) of the rider pedaling (so that the assist force and the human power are the same size). Control.).

In a conventional driving force transmission device applied to an assisted bicycle, a low-speed gear system and a high-speed gear system having different reduction ratios (gear ratios) are provided as gear trains for transmitting the rotational force of a motor. By switching between low-speed gear series or high-speed gear series according to the running speed of the bicycle,
In some cases, motor assist can be performed according to the running speed of the bicycle. The switching of the gear series is a configuration in which a detachable gear is provided at an intermediate stage between the low-speed gear series and the high-speed gear series, and the gear series is switched by attaching and detaching the gear. (JP-A-10-147284).

[0004]

However, in the above-described conventional configuration, when switching from the low-speed gear series to the high-speed gear series (or from the high-speed gear series to the low-speed gear series), the rotational speeds of the drive shaft side and the motor side are synchronized. Not because
When a gear is engaged in a middle stage of a high-speed gear system (or a low-speed gear system), an unstable state occurs temporarily.
For this reason, deadlock and gear damage are likely to occur,
There is a problem that reliability and safety of the driving force transmission device are low. Further, since a configuration for attaching and detaching the gear is required, there is a problem that the manufacturing cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to improve reliability and safety by not mechanically attaching and detaching gears when switching gear trains for transmitting the rotational force of a motor, and to reduce the manufacturing cost. It is to provide a force transmission device.

[0006]

SUMMARY OF THE INVENTION The present invention provides a drive gear that is rotationally driven by a motor, a transmission gear that is mounted on a drive shaft that drives the body by rotating the motor, and a drive gear that rotates when the motor rotates forward. A first gear train for transmitting rotation to the transmission gear via a first one-way clutch, and transmitting the rotation of the drive gear to the transmission gear via a second one-way clutch when the motor rotates in reverse. And a second gear train, wherein the gears constituting the first and second gear trains are mounted on a shaft whose position is fixed.

[0007] The first and second gear trains include:
Different gear ratio.

Further, the drive shaft is provided with a manual drive mechanism for rotating the drive shaft manually.

In this configuration, when the motor rotates forward, the rotation of the motor is transmitted to the transmission gear via the first gear train.
At the time of reverse rotation of the motor, the rotation of the motor is transmitted to the transmission gear via the second gear train. Further, since the gears constituting the first and second gear trains are mounted on shafts whose positions are fixed, there is no gear that is detached from the first and second gear trains when switching between forward and reverse rotation of the motor. . That is, when switching the gear train that transmits the torque of the motor, the gears are not mechanically attached or detached, so that reliability and safety can be improved. Further, since a mechanism for attaching and detaching the gear is unnecessary, the cost can be reduced.

[0010]

FIG. 1 is a diagram showing a configuration of an assisted bicycle to which a driving force transmission device according to an embodiment of the present invention is applied. 1 is the main frame of the bicycle, 2
Is a steering wheel, 3 is a front wheel, 4 is a rear wheel, and 5 is a saddle. Reference numeral 6 denotes a foot pedal (hereinafter, simply referred to as a pedal) pedaled by a rider, 7 denotes a pedal shaft which rotates when the pedal 6 is pedaled, 8 denotes a first sprocket which rotates together with the pedal shaft 7, 9 Is a second sprocket attached to the rotating shaft of the rear wheel 4. First sprocket 8
A chain 10 is wound around the second sprocket 9 and the rear wheel 4 rotates when the pedal 6 is pedaled, as is well known, to move the bicycle forward. Reference numeral 11 denotes a driving force transmitting unit that transmits driving force from a motor to the pedal shaft 7, and reference numeral 12 denotes a control device that controls the motor provided in the driving force transmitting unit 11. The control device 12 includes a battery, and supplies operating power to the motor from the battery. The pedal shaft 7 corresponds to the drive shaft according to the present invention.

FIG. 2 is a view showing the configuration of the driving force transmitting section, and FIG. 3 is a view taken in the direction of arrow A in FIG. 7 is
This is the pedal shaft described above, and the pedal 6 is attached to both ends of the pedal shaft 7. Reference numeral 21 denotes a motor fixed to a frame or the like (not shown).
It is a rotation axis. A gear 22 and a clutch member 23 are fixed to the rotating shaft 21a, and the gear 22 and the clutch member 23 rotate together with the rotating shaft 21a. Gear 2
2 and the clutch member 23 correspond to a drive gear referred to in the present invention. A gear 24 is further attached to the rotating shaft 21a via a bearing.
3 is attached so as to be connected via a one-way clutch 25 (corresponding to a second one-way clutch according to the present invention). The one-way clutch 25 according to this embodiment has an inner clutch portion provided on the clutch member 23, an outer clutch portion provided on the gear 24, and a ball disposed between the inner clutch portion and the outer clutch portion. When the motor 21 rotates in the reverse direction, the inner clutch portion and the outer clutch portion are locked (coupled) via the ball and rotate integrally, and the lock is released when the motor 21 rotates forward. Things.

Reference numeral 26 denotes a fixed shaft fixed to a frame or the like (not shown), and a gear 27 and a gear 28 are attached to the fixed shaft 26 via bearings. Gear 2
The gear 7 and the gear 28 are mounted so as to be connected via a one-way clutch 29 (a first one-way clutch according to the present invention). The one-way clutch 29 also has the same configuration as the one-way clutch 25 described above, and the gear 27 and the gear 28 rotate integrally when the gear 27 rotates in the reverse direction (when the motor 21 rotates forward). Reference numeral 30 denotes a transmission gear attached to the pedal shaft (corresponding to a transmission gear referred to in the present invention), and is a one-way transmission that is free with respect to the pedal shaft 7 when the rider reverses the pedal 6. It is attached to the pedal shaft 7 via a mechanism. Further, the gear 27 meshes with the gear 22 and rotates with the rotation of the motor 21, and the gears 24 and 28 mesh with the transmission gear 30, respectively, and the gears 24 and 28 and the transmission gear 30 rotate in conjunction with each other.

Next, the operation of the driving force transmission unit 11 will be described. When the motor 21 rotates forward, the gear 22 and the clutch member 23 fixed to the rotation shaft 21a rotate clockwise, and the gear 27 receives the rotation of the gear 22 and rotates counterclockwise. The gear 27 rotating counterclockwise rotates integrally with the gear 28 connected by the one-way clutch 29. Accordingly, a clockwise rotational force is applied to the transmission gear 30 from the gear 28 rotating counterclockwise, and the pedal shaft 7 rotates clockwise. On the other hand, the gear 24 is not connected to the clutch member 23 rotating in the clockwise direction by the one-way clutch 25. Therefore, the torque of the motor 21 is not transmitted to the gear 24, and the torque of the motor 21 is not applied to the transmission gear 30 from the gear 24. Thus, the motor 21
Gear 22 → gear 27 → one-way clutch 2
The torque of the motor 21 is transmitted to the pedal shaft 7 through a gear series (low-speed gear series) consisting of 9 → gear 28 → transmission gear 30, but the clutch member 23 → gear 24 → transmission gear 3
Motor 2 through a gear train (high-speed gear train) consisting of
No one rotational force is transmitted.

When the motor 21 rotates in the reverse direction, the gear 22 and the clutch member 23 fixed to the rotating shaft 21a rotate counterclockwise, and the gear 27 receives the rotation of the gear 22 and rotates clockwise. Since the gear 28 rotating clockwise is not connected to the gear 28 by the one-way clutch 29, the torque of the motor 21 is not transmitted to the gear 28. On the other hand, the clutch member 23 rotating counterclockwise rotates integrally with the gear 24 connected by the one-way clutch 25. Thus, a clockwise rotational force is applied to the transmission gear 30 from the gear 24 rotating counterclockwise, and the pedal shaft 7 rotates clockwise. Thus, when the motor 21 rotates in the reverse direction, the torque of the motor 21 is transmitted to the pedal shaft 7 via the high-speed gear train.

As described above, the driving force transmission device of this embodiment can switch the gear train for transmitting the torque of the motor 21 to the transmission gear 30 by the forward / reverse rotation of the motor 21. Further, since gears are not mechanically attached / detached when switching gear trains, an unstable state occurs at the time of gear train switching (during attachment / detachment of gears), which causes problems such as deadlock and gear breakage. As a result, reliability and safety can be improved without any occurrence, and a mechanism for attaching and detaching a gear is not required, so that manufacturing costs can be reduced.

Although the one-way clutches 25 and 29 need not have the above-described structure, it is preferable that the load at the time of reverse rotation is small. Further, the gear 22 and the clutch member 23 may be a single gear integrally formed. further,
The gear 22, the clutch member 23 and the gear 24 are connected to the motor 2
Although the motor 21 is attached to the one rotating shaft 21a, it may be attached to a rotating shaft that transmits the torque of the motor 21 and rotates the motor 21.

Next, the assist control when the bicycle shown in FIG. 1 runs will be described. FIG. 4 is a block diagram illustrating a configuration of the control unit. The control unit 12 includes the motor 2
A control circuit 52 for controlling the rotational force and the rotational direction of the motor 21;
And a sensor 54 for detecting the number of rotations of the gear 28. In this embodiment, the motor 21 is a DC servo motor, and the speed ratio between the high-speed gear train and the low-speed gear train is 1: 3. Further, the gears 27, 28, and 24 have the same number of teeth, and the gears 24 and 28 have the same outer diameter. Sensor 5
Reference numerals 3 and 54 face the teeth of the gears 27 and 28, respectively, and output pulse signals corresponding to the number of teeth of the rotating gears 27 and 28. In addition, as a configuration for detecting the number of teeth of the gears 27 and 28 by the sensors 53 and 54, the gear 2
A method of detecting the teeth 7 and 28 or a method of detecting a signal proportional to the rotation of the gears 27 and 28 via a separately provided disk or the like may be used. Control circuit 52
Controls the motor 21 based on pulse signals output from the sensors 27 and 28.

FIGS. 5 to 7 are diagrams showing the relationship between the detection pulses of the sensors 53 and 54 and the rotational force of the motor 21 when the bicycle is running. When the bicycle is stopped, the control unit 12 does not supply operating power to the motor 21, so that the motor 21 does not run the bicycle by itself.

At time t1 shown in FIG. 5, when the rider steps on the pedal 6 to start running, the transmission gear 30 rotates clockwise together with the pedal shaft 7. Thus, the gear 24 and the gear 28 rotate counterclockwise in conjunction with the rotation of the transmission gear 30. At this time, the one-way clutch 25,
29, the gear 24 and the clutch member 23 and the gear 28 and the gear 27 are not connected to each other.
Is not transmitted to the rotating shaft 21a of the motor 21. That is, the low-speed gear series for the passenger,
The high-speed gear train and the rotating shaft 21a of the motor do not cause unnecessary load, and the pedal 6 can be pedaled with the same feeling as a bicycle without an assist mechanism.

When the bicycle starts running (time t1 shown in FIG. 5)
-T2), the sensor 53 does not output a pulse signal because the gear 27 is not rotating. On the other hand, the sensor 54
8 rotates in conjunction with the transmission gear 30, so that the gear 2
The pulse signal corresponding to the rotation speed of No. 8 is output. The pulse interval of the pulse signal output from the sensor 54 changes according to the speed of the bicycle, and becomes narrower as the speed of the bicycle increases.

The control unit 12 supplies operating power to the motor 21 when a certain time has elapsed since the start of running of the bicycle (at time t2 shown in FIG. 5). At this time, the control unit 12 rotates the motor 21 forward. The forward rotation of the motor 21 causes the gear 27 to rotate counterclockwise via the gear 22. The sensor 53 outputs a pulse signal corresponding to the rotation speed of the gear 27 when the gear 27 starts rotating.

When the control section 12 starts the rotation of the motor 21, the rotational force (the number of revolutions) gradually increases, so that the pulse interval of the pulse signal output from the sensor 53 also gradually narrows. In this embodiment, since the gear 27 and the gear 28 have the same number of teeth, the sensor 53 and the sensor 5
4 is proportional to the difference between the rotational speeds of the gears 27 and 28.

When the control unit 12 starts the rotation of the motor 21, the rotation speed of the gear 27 is lower than the rotation speed of the gear 28, so that the one-way clutch 29
And the gear 28 are not connected. That is, the rotational force of the motor 21 is not transmitted to the gear 28,
You are traveling without assist by Control unit 12
Increases the rotational force of the motor 21, and when the rotational speed of the gear 27 reaches the rotational speed of the gear 28 (at time t shown in FIG. 6).
3), the gear 27 and the gear 28 by the one-way clutch 29
Are connected and rotate integrally. Therefore, the rotational force of the motor 21 is transmitted to the transmission gear 30 from the gear 28, and assist by the motor 21 is started.

When the pulse intervals of the pulse signals output from the sensors 53 and 54 become equal, the controller 12 (the gear 2
When the rotation speed of the motor 7 reaches the rotation speed of the gear 28), the control for gradually increasing the rotation force of the motor 21 ends, and conversely, the rotation force of the motor 21 is gradually reduced. When the intervals between the pulse signals output from the sensors 53 and 54 are different (when the interval between the pulse signals output from the sensor 54 is smaller), the rotational force of the motor 21 is gradually increased. As described above, the control unit 12 gradually decreases the rotational force of the motor 21 when the pulse intervals of the pulse signals output from the sensors 53 and 54 are equal, and when the pulse signal intervals are different, the control unit 12 adjusts the rotational force of the motor 21. Is repeated so that the pulse intervals of the pulse signals output from the sensors 53 and 54 become equal.
1 is controlled.

Here, since the gear 28 rotates in conjunction with the rotation of the transmission gear 30 which is rotated by the rider rowing the pedal 6, when the gear 27 has the same rotation speed as the gear 28,
The assist force from the motor 21 applied to the transmission gear 30 is the same as the force of the rider pedaling the pedal 6. Therefore, the control unit 12 controls the rotational force of the motor 21 so that the pulse intervals of the pulse signals output from the sensors 53 and 54 become equal, thereby coping with the fluctuation of the human power of the passenger pedaling the foot pedal 6. while doing,
The assist force from the motor 21 can be controlled to the same magnitude as human power.

During normal rotation of the motor 21, the clutch member 23 is rotating clockwise, and the one-way clutch 25 does not connect the gear 24. Therefore,
The torque of the motor 21 is not transmitted to the transmission gear 30 via the high-speed gear train.

When the running speed of the bicycle exceeds a predetermined speed, the control unit 12 switches from a low-speed gear series to a high-speed gear series. The running speed of the bicycle can be detected from the pulse interval of the pulse signal output from the sensor 54. When the running speed of the bicycle exceeds a predetermined speed (time t4 shown in FIG. 7), the control unit 12 gradually reduces the rotational force of the motor 21 and reverses the motor 21 at time t5 (counterclockwise). Rotate.) The reverse rotation of the motor 21 causes the gear 22 and the clutch member 23 to rotate counterclockwise. When the gear 22 rotates in the counterclockwise direction, the gear 27 rotates in the clockwise direction. Therefore, the gear 27 and the gear 28 are not connected by the one-way clutch 29, and the torque of the motor 21 is not transmitted to the gear 28. Absent.
That is, when the motor 21 rotates in the reverse direction, the torque of the motor 21 is not transmitted to the transmission gear 30 via the low-speed gear train.

On the other hand, although the clutch member 23 rotates in the counterclockwise direction, when the motor 21 rotates in the reverse direction, the rotation speed is lower than that of the gear 24 (time t5 to t6 shown in FIG. 7).
It is not connected to the gear 24 by the one-way clutch 25.
Accordingly, the clutch member 23 and the gear 24 do not rotate integrally, and the transmission gear 30 is in a state where the torque of the motor 21 is not transmitted. That is, the bicycle is motor 2
This means that the vehicle is traveling without assist by No. 1. The control unit 12 gradually increases the rotational force of the motor 21 as in the case of the low-speed gear series described above. When the rotation speed of the clutch member 23 reaches the rotation speed of the gear 24, the clutch member 23 and the gear 24 are connected by the one-way clutch 25 and rotate integrally, so that the torque of the motor 21 is transmitted to the transmission gear 30. Then, assist by the motor 21 is performed.

Here, in this embodiment, since the speed ratio between the low-speed gear train and the high-speed gear train is 1: 3 as described above, the output from the sensor 54 corresponds to the pulse signal output from the sensor 53. Pulse signal interval is 1:
3, the rotational speed of the clutch member 23 and the gear 24
Is equal to the rotation speed of As in the case of the normal rotation of the motor 21 described above, the control unit 12 increases or decreases the rotational force of the motor 21 so that the pulse width of the pulse signal output from the sensor 53 and the sensor 54 becomes 1 : 3, the rotational force of the motor 21 is controlled. Thus, the assist force from the motor 21 can be controlled to the same magnitude as the human power while responding to the fluctuation of the human power while the rider is stepping on the foot pedal 6. Note that the gear 24 and the gear 28 have the same outer diameter and fraction as described above.

As described above, when the bicycle is running at a speed lower than the predetermined speed, the running assist is performed through the low-speed gear train. When the bicycle is running at a speed exceeding the predetermined speed, the running assist is performed through the high-speed gear train. Can be assisted. That is, the motor 2 depends on the running speed of the bicycle.
It is possible to switch the gear series that transmits one rotational force. Further, when switching between the low-speed gear series and the high-speed gear series by the forward / reverse rotation of the motor 21, the gears are not mechanically attached or detached. Reliability and safety against deadlock and gear damage can be improved. Also,
Since the mechanism for mechanically attaching and detaching the gear is unnecessary,
Manufacturing costs can also be reduced.

When the running speed of the bicycle falls below a predetermined speed, the control unit 12 switches from a high-speed gear series to a low-speed gear series (switches the motor 21 from reverse rotation to normal rotation). Switching from the high-speed gear series to the low-speed gear series is a process of performing the above-described switching from the low-speed gear series to the high-speed gear series in reverse.

Furthermore, when the bicycle is running, the rider may reverse or stop the pedal 6. Therefore, if the transmission gear 30 is integrally fixed to the pedal shaft 7, the motor 21 A large load may be applied.
For this reason, in this embodiment, as described above, the transmission gear 3
Numeral 0 is attached to the pedal shaft 7 via a one-way transmission function so that the pedal shaft 7 is free when the pedal shaft 7 rotates in the reverse direction. Thus, for example, when the occupant stops the pedal 6 while traveling down a hill or when the pedal 6 is reversed, the gear 24 and the gear 28 do not rotate. As a result, reliability and safety against damage to the motor 21 are sufficiently ensured.

Although the torque of the motor 21 is transmitted to the transmission gear 30 attached to the pedal shaft 7 in the above embodiment, the transmission gear 30 is attached to the rotation shaft of the rear wheel 4 of the bicycle, and the torque of the motor 21 is transmitted. May be transmitted to the transmission gear 30. In the above embodiment, the example in which the driving force transmission device of the present invention is applied to an assisted bicycle has been described. However, the invention can be similarly applied to an electric cart or another vehicle that runs by the rotational force of a motor. it can.

[0034]

As described above, according to the present invention, the gear is not mechanically disengaged when switching between the low-speed gear system and the high-speed gear system in accordance with the running speed of the bicycle. The reliability and safety can be improved without being in a stable state, and the manufacturing cost can be reduced because the mechanism for attaching and detaching the gear is unnecessary.

[Brief description of the drawings]

FIG. 1 is a diagram showing a bicycle to which a driving force transmission device according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a configuration of a driving force transmission device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a driving force transmission device according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of a control unit of the driving force transmission device according to the embodiment.

FIG. 5 is a diagram showing an operation of the driving force transmission device of the embodiment.

FIG. 6 is a diagram showing an operation of the driving force transmission device of the embodiment.

FIG. 7 is a diagram showing an operation of the driving force transmission device of the embodiment.

[Explanation of symbols]

 7-Pedal shaft 21-Motor 21a-Rotating shaft 22,24,27,28-Gear 23-Clutch member 25,29-One-way clutch 26-Fixed shaft 30-Transmission gear

Claims (3)

[Claims] A driving gear rotatably driven by a motor; a transmission gear mounted on a driving shaft for driving the main body by rotating the driving gear; and a first one-way clutch for rotating the driving gear when the motor rotates forward. A first gear train for transmitting the rotation of the drive gear to the transmission gear via a second one-way clutch when the motor rotates in the reverse direction. The driving force transmission device, wherein the gears constituting the first and second gear trains are attached to a shaft whose position is fixed. 2. The driving force transmission device according to claim 1, wherein the first and second gear trains have different gear ratios. 3. The driving force transmission device according to claim 1, wherein the driving shaft is provided with a human driving mechanism for rotating the driving shaft manually.