JP3141345B2 - Bicycle with drive assist device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle with a driving force assisting device which assists human power with an assisting driving force when a heavy load is applied.

[0002]

2. Description of the Related Art In order to assist driving force by human power, there has been proposed a device configured to operate an auxiliary motor based on only driving force by human power as disclosed in Japanese Patent Application Laid-Open No. 2-74491. In this device, there is no idea to determine the ratio of assist power and human power according to the speed of the vehicle,
Since the driving force by human power decreases with an increase in the speed of the vehicle, the auxiliary force only decreases.

For this reason, when the vehicle speed increases, the absolute value of the assisting force decreases, but the ratio between the assisting force and the human power becomes
It may increase or decrease. FIG. 9 shows this state. When the total torque is indicated by a line D and the auxiliary torque by the motor is indicated by a line d ', the manner of changing the ratio between the auxiliary torque and the manual torque differs depending on the torque characteristics of the motor. FIG. 9A shows a case where a motor whose torque reduction rate is small with respect to the speed is used, FIG. 9B shows a case where a motor whose torque reduction rate is large is used, and FIGS. In both cases, the absolute value of the assisting force decreases in the high vehicle speed range, but the ratio (D / d ') of the assisting force to the human power in the total torque differs depending on the setting of the motor torque characteristics.

[0004]

In a vehicle with an auxiliary power unit, it is preferable that the assisting force is reduced when the vehicle is running at a high speed, due to the characteristics of the vehicle with the auxiliary power unit.
At that time, it is also an object of the present invention to obtain a vehicle which is suitable as an assisted vehicle, and which allows a driver to clearly recognize that the assist torque is decreasing, paying attention to a change in the ratio of the assist torque to the human power. .

[0005]

Means for solving the above-mentioned problems in the present invention is such that the pedal human-powered driving means and the auxiliary power driving means are connected to the wheels in parallel, as described in claim 1. In the bicycle with the driving force assisting device, the Tcp detecting means for the rotational torque applied by the pedal human driving means, and the pedal crank rotation speed Nc
And the ratio of the auxiliary driving force to the manual driving force Tcp is increased as the vehicle speed increases at a high vehicle speed at a predetermined work amount based on the two detection values. , The change point where the ratio gradually decreases
At the same time, the change point corresponds to the increase or decrease of the human driving force Tcp.
The rotation speed of the pedal crank is set to be different from the rotation speed of the pedal crank .

According to the above-mentioned means, when the rotation speed Nc of the pedal crank reaches a predetermined high-speed range with respect to a work amount curve determined by the work amount Wcp based on the detected values of the manual driving force and the auxiliary driving force, Since the ratio of the auxiliary driving force to the driving force gradually decreases and the ratio of the manual driving force gradually increases, the driver can feel the degree of speed during high-speed running.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a bicycle embodying the present invention, 2 denotes a frame, 3 denotes a steering wheel, 4 and 5 denote front and rear wheels, 6 denotes a pedal crank, and 6a (FIG. 3) denotes a crank speed. A detector 7 is a driving sprocket fixed to a shaft of a pedal crank 6, and a driven sprocket 8 is fixed to a shaft of a rear wheel 5, and a chain 9 is wound around both sprockets 7 and 8. Is a well-known device that travels by rotating the pedal crank 6 with human power.

In the bicycle 1, reference numeral 10 denotes a driving force assisting device. An assisting sprocket 13 and an electric motor 14 for driving the assisting sprocket 13 are mounted on a lever 12 pivotally connected to a seat tube 11 of a frame 2 by a pin 12a. Lever 1
A load cell 15 serving as a tension detector for the chain 9 is interposed between the seat tube 11 and the seat tube 11 to press the auxiliary sprocket 13 against the chain 9. The auxiliary sprocket 13 is engaged with the tension side 9a of the chain 9, and the motor 14 is driven by the current supplied from the battery 16 by the cord 17, and the supply voltage is controlled by the output of the load cell 15 (not shown). It is controlled by a voltage regulator.

When the load applied to the rear wheel 5 during traveling by human power increases and the force applied to the crank 6 correspondingly increases, the tension side 9a of the chain 9 tries to become linear and the auxiliary sprocket 13 and the arm 12, the load cell 15 is compressed to control the voltage of the power supply circuit of the motor 14 by the output thereof to drive the motor 14 and transmit the torque to the chain 9 to assist human power.

FIG. 2 is an explanatory view of the force acting on the load cell 15, wherein the tension of the chain 9 is Tp, the auxiliary sprocket 13
Is Ta, a force of Tp + Ta acts on the chain portion upstream of the auxiliary sprocket 13. When the lever 12 is disposed substantially parallel to the chain portion, Tp + Ta acts in the longitudinal direction of the lever 12, and Tp and
Although the resultant force Tt of Tp + Ta is obtained, the component Ts of the resultant force Tt perpendicular to the lever 12 is independent of the magnitude of Tp + Ta or Ta, and is proportional only to Tp.

Since the force F acting on the load cell 15 is proportional to Ts, the force F is proportional to the chain tension Tp. Therefore, the voltage for driving the motor controlled by the load cell 15 is also controlled by the chain tension Tp. Electric power corresponding to human power applied to the pedal crank 6 is supplied.

In the embodiment shown in FIG. 3, the motor 14 is fixed to a motor stay 20 fixed to the seat tube 11,
The support shaft of the lever 12 is coaxial with the motor 14, and the lever 1
2, a drive pinion 21 is fixed to the output shaft of the motor 14 as a reduction gear to drive a large-diameter auxiliary gear 22, the gear 22 integral with the auxiliary sprocket 13 meshes with the chain 9. Also in this device, if the chain tension increases, the pressure of the load cell 15 increases and the motor 14 operates.

In the embodiment shown in FIG. 4, the motor 14 and the auxiliary sprocket 13 are arranged on the lever 12 in substantially the same configuration as that in FIG. 1, but the reduction gear having the same configuration as that in FIG. 3 is used.

FIGS. 5 and 6 show the seat tube 1.
1 has a forward curved portion 11a, a plate-shaped receiving portion 11b having a U-shaped contour and integrally projecting forward with the curved portion 11a, the arm 12 is pivotally attached to a down tube 23, and an electric motor Reference numeral 14 is located inside the curved portion 11a, and the load cell 15 is connected to the arm 12 with a pin 12b, and the upper surface of the load cell 15 is in contact with the lower surface of the receiving portion 11b. Also in this device, when the pedal driving force increases and the tension on the tension side 9a of the chain increases, power is supplied to the motor 14 by a signal from the load cell 15.

In each of the above embodiments, if the work amount of the manual power applied from the pedal is Wcp, the crank pedaling torque Tcp, and the crank speed is Nc, Wcp = (1/1 /
716.2) It is expressed by Tcp · Nc. In the case of human power, the relationship between Tcp and Nc is actually as shown in FIG.
The product of the crank pedaling torque Tcp and the crank speed Nc is represented by curves a to d approximating a constant hyperbola, and the line moves in the direction of the arrow when the momentum Wcp increases. In each of the curves a to d, the momentum Wcp is constant.

The relationship between the auxiliary drive torque Tca of the DC motor by the voltage control and the crank speed Nc is shown in FIG.
The auxiliary drive torque T as shown by the straight lines a 'to d' in FIG.
The rotational speed Nc is inversely proportional to the rotational speed Nc, and the straight line moves in the direction of the arrow when the applied voltage Va increases. Tca,
Va = KE · Nc + (Ra) between Nc and the applied voltage Va.
/ KT) Tca, where KE is the induced voltage constant, Ra
Is the armature resistance and KT is the torque constant. Curves a 'to d
In each curve ', the applied voltage Va of the motor is constant.

When the motor 14 is operated during the manual operation by the pedal and the motor 14 is operated in cooperation with the manual operation, the curves a to b are raised and the curves A to D shown in FIG. Become. In FIG. 7, Tc is a crankshaft equivalent output torque,
Tca is the auxiliary driving torque of the DC motor, and R is the running resistance.

In FIG. 7C, the human power is raised by the auxiliary driving force, and the total driving force changes as indicated by curves A, B, C, and D along the line W. The curves A to D correspond to the lines a ′ to a
It is closest to d '. In curves D and d ', in the region above the running resistance curve R pedal crank speed in high speed range (high speed side of the line W), when the speed is, for example, n _1, the auxiliary torque P _1, manpower torque Q ₁ and also assist torque when the speed is n ₂ is P _2, manpower torque Q _2.

The aforementioned P ₁ , P _2, etc. are used as auxiliary torques P, Q ₁ , Q ₂
Assuming that human torque Q is the human torque, the ratio of assist torque P to human torque Q, that is, the assist ratio (P / Q) gradually decreases with an increase in speed in a high-speed region, and becomes P ₂ / Q from P ₁ / Q _1. Decrease to ₂ . For this reason, the ratio of the manual torque Q to the total drive torque gradually increases. By gradually decreasing the assist ratio, the driver can feel the speed increase and the end of the assist, and can provide a feeling suitable for the assist vehicle. The curve D,
Although the description has been made with respect to d ', the same effect occurs in the curves C and c'. In each of the curves A to D, the vehicle speed becomes the upper limit at the intersection with the running resistance curve R.

The control operation by the voltage adjusting device (not shown) can be performed according to the chart shown in FIG. That is, when the product Wcp of the crank pedaling torque Tcp and the crank speed Nc becomes larger than the reference value WCP, the voltage Va · Wcp = Tc proportional to the Wcp.
The driving force is added to the motor 14 by generating p × Nc. For example, when the work amount Wcp is the curve c or d in FIG. 7A, the work amounts of the straight lines c ′ and d ′ in FIG. Thereby, the work Wcp based on the crank pedaling torque Tcp and the crank speed Nc
Is larger than a predetermined value, the voltage Va applied to the motor is controlled according to the work amount Wcp.

FIGS. 7A to 7C show that the curves a to d
, The relationship between the auxiliary torque Tca and the
The ratio Tca / Tcp or P / Q of the torque Tcp (assist
Tca, Tca increases as Nc becomes faster.
Curves a to d decrease while linearly decreasing
And the curves A to D also maintain this relationship.
Therefore, considering the assist ratio, the crank speed
Is increased to the predetermined point, then the assist ratio increases.
Decreases as the speed increases, and increases / decreases the assist ratio
Are substantially along the line W shown in FIG. 7 (c).
It is understood that.

[0022] predetermined pedal torque Tc ₁ in FIG.
The change point is X and the change point in pedal torque Y is Y
And at different positions with the pedal crank speed
Become. As described above, the assist ratio is determined according to the human-power torque Tcp.
Is gradually reduced, and the vehicle speed changes,
Respect, it is favorably recognized a decrease in the assist ratio
it can. That is, in the case of FIG.
The lower the vehicle speed, the lower the assist ratio began to gradually decrease
And vice versa.

The above description has been made of the case using the chain transmission and the electric motor. However, a belt transmission can be used as the transmission, and a hydraulic motor driven by an electric motor can be used as the auxiliary prime mover. It can also be used for manually driven snow vehicles.

The mechanism for transmitting the movement of the auxiliary sprocket or the auxiliary pulley to a tension detector such as a load cell is not limited to a lever, and a cam or other transmission mechanism can be used.
Even if the tension and the output of the tension detector do not always have an accurate proportional relationship, there is no problem in practical use.

[0025]

As is apparent from the above description, according to the present invention, in the high-speed running range past the change point of the assist ratio, the ratio between the auxiliary torque and the human-powered torque is gradually reduced as the speed increases. Since the ratio of human torque is gradually increased, the driver can feel the increase in speed, and the same as a normal bicycle
There is an effect that a feeling of riding is obtained and a feeling suitable for a vehicle with auxiliary power is obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a bicycle embodying the present invention.

FIG. 2 is a diagram illustrating the operation of a tension detection mechanism.

FIG. 3 is a front view of another embodiment.

FIG. 4 is a front view of another embodiment.

FIG. 5 is a front view of another embodiment.

6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is an explanatory diagram of a power assisting action.

FIG. 8 is a flowchart of a control operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Driving force auxiliary device 12 Lever 13 Auxiliary sprocket 14 Electric motor (Auxiliary motor) 15 Load cell (Tension detector)

Claims (2)

(57) [Claims] 1. A bicycle with a driving force assisting device in which a pedal human driving device and an auxiliary power driving device are connected to wheels in parallel, a detecting device for a rotational torque Tcp applied by the pedal human driving device, and a pedal. An auxiliary driving force that is controlled in accordance with both detection values of the crank rotation speed Nc detection means, and which is a human-powered driving force Tcp of the auxiliary driving force.
Has a changing point in which the ratio gradually decreases as the vehicle speed increases at a high vehicle speed at a predetermined work load composed of the two detected values, and the changing point is determined by the human driving force Tcp.
Set different pedal crank rotation speed according to increase or decrease of
Is the characterized in that, the driving force auxiliary device with the bicycle. 2. The bicycle with a driving force assisting device according to claim 1, wherein the high vehicle speed is a speed range near a running resistance at a predetermined work load.