JPH0995287A - Electric bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit the auxiliary power in response to the steering angle so as to prevent the generation of departure and fall of a bicycle. SOLUTION: Electric power to be supplied from a battery power source 2 to an electric motor 3 for assisting the operation of an operation pedal is limited by multiplying the steering angle function expressed with k/θ, which is obtained by multiplying the inverse number of the output steering angle θof a steering angle sensor 12 by a coefficient (k). When a handle is steered right or left at need of a change of traveling route or a turn right and left, the auxiliary power can be restricted in response to the steering angle θ, and a danger that the auxiliary power more then the necessity is supplied during the steering of wheels so that a vehicle is jut out into the opposite lane or fallen can be previously and securely prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric bicycle in which power assistance is limited in accordance with a steering angle to prevent deviation from a running lane or a fall.

[0002]

2. Description of the Related Art An electric bicycle equipped with an electric motor for pedal assist sends auxiliary power from the electric motor to the crankshaft or the sprocket for the rear wheels according to the force (pedaling force) on the foot pedal, and provides a lighter pedaling force. It is structured so that it can be run in the same way as an ordinary bicycle. This type of electric bicycle is equipped with a rechargeable Ni-Cd battery or the like as a battery power source, so that it can be driven with a power assist for a mileage of 20 km or more with one charge on a flat ground. It has become.

In the conventional electric bicycle 1 shown in FIG. 5, a battery power source 2 is detachably mounted on a body frame forming the skeleton of the bicycle. The electric motor 3 for generating auxiliary power is arranged in the vicinity of the battery power source 2, and the generated power is combined with the pedaling force of the foot pedal through the one-way clutch, and the combined power is transmitted through the chain to the rear side. It is transmitted to the wheel gear and drives the rear wheel.

In order to obtain the same running feeling as possible with the conventional foot-operated bicycle, this electric bicycle 1
The output of the electric motor 3 is controlled by the control unit 4 according to the running state.
Has a configuration for controlling appropriately. A DC brush motor is used as the electric motor 3, and the output torque is controlled by pulse width modulation (PWM) control. That is, the control unit 4 intermittently supplies electric power to the electric motor 3 at a high speed cycle to variably control the auxiliary power.
When the output duty (ratio of ON period in one cycle) is small, the power assist of small torque is stopped.
The output torque of the electric motor 3 can be increased almost in proportion to the duty. Q is a switching element that is switching-controlled by the controller 4a in the control unit 4, is connected between the electric motor 3 and the negative terminal of the battery power source 2, and has its conduction period according to the duty determined by the controller 4a. Is variable. The positive terminal of the battery power source 2 and the electric motor 3
A normally open contact 5 of the relay is connected between the and, and is closed by receiving a key operation only when the power assisted traveling is desired,
It enables power supply from the battery power source 2 to the electric motor 3.

Since the control unit 4 controls the auxiliary power in accordance with the running state, the pedal force sensor 6 for detecting the pedaling force of the foot pedal and the crank speed sensor 7 for detecting the rotational speed of the crankshaft are connected to the controller 4a. There is. Therefore, the controller 4a calculates the optimum auxiliary power P according to the pedaling force F and the crankshaft rotation speed N, and makes the switching element Q conductive by the PWM pulse of the duty corresponding to this auxiliary power P, thereby the electric motor 3 Drive control. Since the rotation speed of the electric motor 3 and the rotation speed of the crankshaft are proportional to each other during power assistance, the speed signal detected by the crank speed sensor 7 is converted into the motor rotation speed and used for motor control. Actually, the motor power P is map-controlled according to the pedaling force F of the foot pedal detected by the pedaling force sensor 6 and the crankshaft rotational speed N detected by the crank speed sensor 7, and the output voltage Vb of the battery power source 2 is changed. After making the corresponding voltage correction, the necessary auxiliary power is generated.

The map control is a control method for determining the auxiliary power using a map that defines the relationship between the pedal depression force F, the crankshaft rotation speed N, and the motor power P in a three-dimensional space. The optimum motor power is determined according to the map shown. For this reason, for example, when traveling straight ahead, the electric motor 3 is driven to assist the pedaling force applied to the foot pedal up to a cruising speed of about 15 km / h, but when the cruising speed is exceeded, the auxiliary power is gradually suppressed to a cruising speed of 1 When the auxiliary speed limit of about 5 times is reached, the auxiliary power is set to zero and it is possible to perform fine power assistance such as suppressing the speed from becoming too high. Also, the voltage correction is
In order to perform duty control that is not influenced by the state of charge of the battery power source 2, the output voltage Vb of the battery power source 2 is used to correct the auxiliary power based on the rated output voltage. Here, as shown in FIG. This is performed by multiplying the auxiliary power P by a coefficient γ that is almost inversely proportional to Vb to obtain the effective power γP.

[0007]

The above-mentioned conventional electric bicycle 1 was developed on the premise of a straight running state with the steering wheel kept in a neutral state. When the steering wheel is turned, the course is changed or the vehicle is turned left or right. Power assistance was provided regardless of whether or not he was trying. For this reason, the same power assistance as when driving straight ahead is being provided during steering while turning the steering wheel to the left or right, and as a result, the bicycle would stick out of the driving lane against the driver's intention and the driver would expect Since the vehicle turns in a larger radius than the turning radius that was used, it may collide with a vehicle running in an oncoming lane, be hit by a vehicle behind, or even fall due to a difference in driving and steering sensations. Had a problem.

The present invention has been made in view of the problems of the conventional electric bicycle described above. By limiting the auxiliary power in accordance with the steering angle, the risk of the lane protruding or falling during steering can be avoided. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the above object, the present invention provides a rechargeable battery power source and an auxiliary power source for supplying power from the battery power source to assist a stepping operation on a foot pedal. An electric motor that generates power, a steering angle sensor that detects a steering angle of a steering wheel, a battery power source that is provided between the battery power source and the electric motor, and that increases when an output steering angle of the steering angle sensor increases. And a control unit for suppressing the electric power supplied to the electric motor from the electric motor and limiting the auxiliary power.

Further, according to the present invention, the control unit determines the straight-ahead auxiliary power in accordance with the pedaling force applied to the foot pedal and the crankshaft rotation speed, and the steering-angle sensor outputs the straight-ahead auxiliary power. A steering angle function, which is a function of the steering angle, is calculated to calculate the steering assist power, and power supply control is performed in accordance with the steering assist power, and k / the reciprocal of the steering angle θ is multiplied by a coefficient k. The steering assisting power is calculated by multiplying the steering assisting power by θ as a steering angle function, or the steering angle range in which the steering angle θ can be regarded as going straight or almost going straight (θ ≦ θs)
When the steering angle θ is 1 and the steering angle θ is in the steering angle range (θs <θ) exceeding the steering angle range, the steering angle represented by k / θ obtained by multiplying the reciprocal of the steering angle θ by a coefficient k. A function is multiplied by the straight-ahead assist power to calculate the steered assist power, and further, the coefficient k is increased substantially in proportion to the vehicle speed during low-speed traveling, and the coefficient k is increased when the cruise speed is exceeded. Is set to 1 and the like.

Further, according to the present invention, the rudder angle sensor comprises a pulsar ring made of a magnetic material assembled to a handle stem, a pair of Hall elements for generating pulses having different phases as the pulsar ring passes, and the pair of Hall elements. Performs up counting or down counting based on the output of the Hall element,
And an up-down counter for outputting the absolute rotation position of the pulser ring, or the steering angle sensor is a potentiometer having a variable resistance whose resistance value changes in accordance with the rotation of the handle stem. It is what

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 is a schematic configuration diagram showing an embodiment of an electric bicycle of the present invention, FIG.
FIG. 3 is a schematic configuration diagram showing an embodiment of the steering angle sensor shown in FIG. 1, and FIG. 3 is a circuit configuration diagram of the electric bicycle shown in FIG.

An electric bicycle 11 shown in FIG. 1 has a rechargeable battery power source 2 assembled on a body frame 8 forming the skeleton of the bicycle, and an electric motor 3 for generating auxiliary power.
Is disposed near the battery power supply 2. Electric motor 3
The auxiliary power generated by is combined with the pedaling force of the foot pedal 9 via a one-way clutch (not shown). The combined power is transmitted to the gear of the rear wheel through the chain and drives the rear wheel, as in a general foot-operated bicycle.

A steering angle sensor 12 is incorporated in the connecting portion between the handle stem 10 and the main body frame 8, and the auxiliary power by the electric motor 3 is corrected according to the output of the steering angle sensor 12. In addition to the steering angle sensor 12, a pedaling force sensor 6 and a crank speed sensor 7 are connected to the controller 14a in the control unit 14. As the pedaling force sensor 6, a sensor that detects a twist angle generated on the crankshaft according to the pedaling force as a voltage is used. Also,
As the crank speed sensor 7, a non-contact rotation sensor that magnetically or optically detects the rotation of the crankshaft is used.

The steering angle sensor 12 is, as shown in FIG.
A magnetic type that outputs two-phase pulses having a phase difference of 90 degrees from each other is used, and a pulsar ring 15 fitted and fixed to the handle stem 10 and a pair of Hall elements arranged at different positions along the circumference of the pulsar ring 15. 16 and 17, and an up-down counter 18 for detecting the absolute rotation phase of the pulser ring 15 by counting up or down the outputs of the pair of Hall elements 16 and 17. The pulsar ring 15 is composed of a magnetic disk in which a large number of tooth portions are formed at equal intervals on the circumference, and a pair of Hall elements 16 and 17 for detecting passage of the tooth portions are pulse (A A phase pulse and a B phase pulse are arranged in a predetermined phase relationship so that the A phase pulse is input to the up input terminal of the up / down counter 18 and the B phase pulse is input to the down input terminal. However, the counting operation of the up / down counter 18 is controlled by the AND gate circuit 20 that calculates the logical product of the rising edge pulse of the A phase detected by the rising edge detection circuit 19 and the B phase.
Specifically, if the output of the AND gate circuit 20 is at a high level, the up / down counter 18 counts up based on the phase A pulse supplied to the up input terminal, and conversely, the output of the AND gate circuit 20 is When the level is low, the up / down counter 18 counts down based on the B-phase pulse supplied to the down input terminal. Therefore,
The absolute rotation position of the handle stem 10 can be detected from the count value of the up-down counter 18, and, for example, when the handle at the neutral position is turned in the right turning direction, the count value of the up-down counter 18 becomes positive. When the steering wheel is turned counterclockwise to the left, the count value of the up / down counter 18 decreases in the minus direction (however, the absolute value thereof increases).

The steering angle θ output from the steering angle sensor 12 is
As shown in FIG. 3, it is sent to the controller 14a in the control unit 14 and used for the correction calculation of the auxiliary power. The controller 14a that controls this correction calculation is the original one determined by the pedaling force F and the crank rotation speed N. Auxiliary power P (auxiliary power during straight travel) P = f (F, N) is multiplied by a correction coefficient γ according to the output voltage Vb of the battery power source 2, and the steering angle θ supplied from the steering angle sensor 12 is further calculated. The reciprocal is multiplied by a coefficient k to be multiplied by k / θ as a steering angle function to obtain steering assist power Pr. That is, if expressed by a mathematical expression, the controller 14a performs a correction calculation of Pr = γkP / θ = γkf (F, N) / θ, and adjusts the switching element Q for PWM control according to the steering assist power Pr. Determine the duty. Therefore, when a person who rides on an electric bicycle turns the steering wheel to the left or right for the purpose of changing the course or turning left or right, for example, the larger the steering angle θ at that time, the more the steering assist power Pr is suppressed. .

As described above, according to the electric bicycle 11, the electric power supplied from the battery power source 2 to the electric motor 3 for assisting the stepping of the stepping pedal 9 has a large output steering angle θ of the steering angle sensor 12. Since the structure is so limited, the auxiliary power can be suppressed as the steering angle θ becomes larger when the steering wheel is turned left or right in order to change the course or turn right or left. For this reason, as in the conventional electric bicycle 1, for example, while the steering wheel is turned to the left or right, the same power assistance as when traveling straight ahead is provided, so that the bicycle is unintentionally moved from the traveling lane against the driver's intention. It protrudes,
The vehicle turns in a radius larger than the turning radius expected by the driver, collides with a vehicle traveling in an oncoming lane, is collided with a vehicle behind, or falls due to a difference in driving and steering sensations. Danger can be prevented in advance.

Further, the control unit 14 determines the auxiliary power P for straight traveling according to the pedaling force F and the crankshaft rotational speed N,
This steering assist power P is calculated by multiplying the steering assist power Pr by a value k / θ obtained by multiplying the reciprocal of the steering angle θ output from the steering angle sensor 12 by a coefficient k. Since the power supply is also controlled together, the auxiliary power that provides comfort when running on a flat road is taken into consideration by taking into account the auxiliary power that is required at the start of running when the foot pedal 9 requires pedaling force and when running uphill on a slope. By determining the power P, when driving straight ahead, the electric motor 3 is rotated to assist the force of pedaling the pedal 9 so that the same force as a person pushes up to the cruising speed. It is possible to provide power assistance in which the auxiliary power is gradually reduced and the auxiliary power becomes zero when the auxiliary limit speed of about 1.5 times the cruising speed is reached.

Further, the steering angle sensor 12 is attached to the handle stem 10, and the pulsar ring 15 made of a magnetic material is used.
And a pair of Hall elements 16 and 1 that generate a forward rotation pulse and a reverse rotation pulse having different phases as they pass through the pulser ring 15.
7 and an up / down counter 18 that performs up-counting or down-counting based on the outputs of the pair of Hall elements 16 and 17 and outputs the absolute rotation position of the pulsar ring 15 are provided. The steering angle θ of the steering wheel 10 can be accurately detected from the turning angle of the steering wheel stem 10 which is easily controlled, and the absolute turning position of the pulsar ring 15 can be obtained by turning the steering wheel from the neutral position to the left or right. Since it is also possible to detect the above, it is possible to accurately correct the auxiliary power P when going straight according to the detected steering angle θ.

In the above embodiment, the pulsar ring 1 is used.
Although the rudder angle sensor 12 in which 5 and the hall elements 16 and 17 are combined is used, like the rudder angle sensor 22 shown in FIG.
A potentiometer configured to detect a change in the orientation of the handle stem 10 as a voltage associated with a change in the resistance value of the variable resistor 23 can also be used. In this case, the steering angle θ of the steering wheel can be detected with accuracy according to the resolution of the variable resistor 23, and since there is almost no deterioration over time, the neutral position will not be erroneously recognized even if the steering wheel is turned left or right, and the absolute steering wheel It is possible to accurately correct the auxiliary power when going straight according to the turning position.

In the above embodiment, a vehicle speed sensor (not shown) for detecting the vehicle speed from the wheel speed is connected to the controller 14a in the control unit 14, and the coefficient k is approximately proportional to the vehicle speed until the cruising speed is reached. The coefficient k may be set to 1 when the cruise speed is exceeded. In this case, in consideration of the situation that the straightness increases and the steering wheel becomes difficult to turn as the vehicle approaches high speed, the balance between the fall prevention during steering and power assistance can be optimized according to the driving situation, and the vehicle speed can be increased. The steering assist power Pr can be brought closer to the straight assist power P as the steering angle is increased, and when the steering angle is increased at the time of starting, the power assistance can be almost disabled to prevent the vehicle from tipping over.

Further, the auxiliary power is not suppressed except when the vehicle is traveling straight ahead when the steering angle θ is zero, and the steering angle range in which the straight steering angle θ can be regarded as straight traveling or substantially straight traveling (for example, θ ≦ 15)
Angle), the steering angle function is fixed to 1, and only when the steering angle θ is in the steering angle range (15 ° <θ), the steering assist function for straight ahead is used by using the steering angle function k / θ. It is also possible to correct P. In this case, even if the steering angle is slightly touched to the left and right, when it can be regarded as straight traveling, the same power assistance as in straight traveling (θ = 0 °) in the strict sense can be received, which causes a meandering habit. People can enjoy comfortable driving by receiving power assistance while driving straight ahead.

In the above embodiment, the electric motor is connected to the crankshaft of the foot pedal, but the electric motor may be connected to the sprocket provided on the rear wheel shaft.

[0024]

As described above, according to the present invention,
Since the electric power supplied from the battery power source to the electric motor that assists the stepping of the foot pedal is suppressed when the output rudder angle of the rudder angle sensor is increased, the handlebar is used like a conventional electric bicycle, for example. During steering turning to the left or right, because the same power assistance as when driving straight ahead was performed,
The bicycle protrudes from the driving lane against the driver's intention and turns with a large radius beyond the turning radius expected by the driver, colliding with a vehicle running in the opposite lane or being collided with a rear vehicle. Further, it is possible to prevent the danger of falling due to the difference between the driving feeling and the steering feeling in advance.

Further, the control unit determines the straight-ahead auxiliary power in accordance with the pedaling force applied to the foot pedal and the crankshaft rotation speed, and the straight-ahead auxiliary power is a function of the steering angle output by the steering angle sensor. Since the steering assist function is calculated by calculating a certain rudder angle function and the power supply is controlled in accordance with the assist power during steering, the foot pedal is required to have a pedaling force. Considering the auxiliary power needed at times, by determining the auxiliary power that brings comfort when traveling on a flat road as the auxiliary power for straight traveling,
For example, up to the cruising speed, the electric motor is turned so that the same force as a person pulls can be generated to assist the power to pedal the pedal, and when the cruising speed is exceeded, the auxiliary power is gradually suppressed, and when the auxiliary limit speed is reached, the auxiliary power is reached. Power assist such as zero is possible, and consideration is given to safe driving by calculating the above-mentioned straight-ahead assist power according to the steering angle of the steering wheel when turning left or right, or when steering due to a change of course. This has the effect of being able to calculate the truly necessary steering assist power.

Further, the control unit is configured to calculate the steering assisting power by multiplying the steering assisting power by k / θ obtained by multiplying the reciprocal of the steering angle θ by a coefficient k as a steering angle function. When the steering wheel is turned to the left or right due to the necessity of changing or turning left or right, the larger the steering angle θ at that time is, the more the steering assist power Pr is suppressed, and the lane sticks out or falls during steering. This has the effect of being able to favorably prevent accidents and the like.

Furthermore, the control unit is 1 when the steering angle θ is in the steering angle range (θ ≦ θs) where the steering angle θ can be considered to be straight or almost straight, and the steering angle θ exceeds the above steering angle range ( When θs <θ), the coefficient k is added to the reciprocal of the steering angle θ by k
Since a steering angle function represented by / θ is calculated by multiplying the straight-ahead assist power to calculate the steered assist power, it is strictly necessary to consider straight running even if the rudder angle slightly touches left and right. In this sense, it is possible to receive the same power assistance as when driving straight ahead (θ = 0 °), which allows people with meandering habits to receive power assistance almost straight ahead and enjoy comfortable driving. And so on.

Further, since the control unit increases the coefficient k substantially in proportion to the vehicle speed during low speed traveling and sets it to 1 when the cruising speed is exceeded, as the vehicle approaches high speed traveling, straightness increases and steering In consideration of the fact that it becomes difficult to turn the steering, it is possible to optimize the balance between overturning prevention and power assistance at the time of steering according to the traveling situation, and as the vehicle speed increases, the steering assistance power becomes straight assistance power. It is possible to bring them closer to each other, and when the steering angle is large at the time of starting, the power assistance is almost ineffective to prevent the fall.

Furthermore, the steering angle sensor has a pulsar ring made of a magnetic material attached to the handle stem, a pair of Hall elements for generating pulses having different phases as the pulsar ring passes, and outputs of the pair of Hall elements. Based on the up-down counter that performs up-counting or down-counting based on the above and outputs the absolute rotation position of the pulsar ring, the steering angle of the steering wheel can be determined from the rotation angle of the handle stem that is easily exposed to rainwater or dust. Can be detected accurately regardless of the steering angle, and the absolute turning position of the pulsar ring can be detected by turning the steering wheel from the neutral position to either the left or right direction. There is an effect that it can be corrected accurately.

Further, since the steering angle sensor is composed of a potentiometer having a variable resistance whose resistance value changes in accordance with the rotation of the steering wheel stem, the steering wheel steering angle can be detected with accuracy according to the resolution of the variable resistance. Since there is little deterioration over time, the neutral position will not be mistakenly recognized even if the steering wheel is turned to the left or right, and the auxiliary power during straight traveling can be accurately corrected according to the absolute turning position of the steering wheel. Play.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an electric bicycle of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the steering angle sensor shown in FIG.

FIG. 3 is a circuit configuration diagram of the electric bicycle shown in FIG.

FIG. 4 is a schematic configuration diagram showing another embodiment of the steering angle sensor shown in FIG.

FIG. 5 is a schematic configuration diagram showing an example of a conventional electric bicycle.

FIG. 6 is a diagram showing a three-dimensional map for determining the motor power from the motor rotation speed and the pedal effort.

FIG. 7 is a diagram showing a relationship between a correction coefficient for correcting auxiliary power according to a battery voltage and a battery detection voltage.

[Explanation of symbols]

 2 battery power supply 3 electric motor 6 pedal force sensor 7 crank speed sensor 8 body frame 9 foot pedal 10 handle stem 11 electric bicycle 12,22 rudder angle sensor 14 control unit 14a controller 15 pulser ring 16,17 hall element 18 up / down counter 19 rising edge Detection circuit 20 AND gate circuit 23 Variable resistance

Claims (7)

[Claims] 1. A rechargeable battery power source, an electric motor that is supplied from the battery power source and generates auxiliary power for assisting the stepping motion of a foot pedal, a steering angle sensor that detects a steering angle of a steering wheel, and A control unit that is provided between a battery power source and the electric motor and that suppresses the electric power supplied from the battery power source to the electric motor when the output steering angle of the steering angle sensor increases to limit the auxiliary power. An electric bicycle comprising: 2. The control unit determines a straight-ahead auxiliary power according to a pedaling force applied to a foot pedal and a crankshaft rotation speed, and the straight-ahead auxiliary power is a function of a steering angle output by the steering angle sensor. The electric bicycle according to claim 1, wherein the steering angle function is calculated to calculate the steering assist power, and the power supply is controlled according to the steering assist power. 3. The control unit calculates the steering assist power by multiplying the straight advance assist power by k / θ obtained by multiplying a reciprocal of the steering angle θ by a coefficient k as a steering angle function. The electric bicycle according to claim 2. 4. The control unit is 1 when the steering angle θ is in a steering angle range (θ ≦ θs) where the steering angle θ can be considered to be straight or almost straight, and the steering angle θ exceeds the steering angle range ( θ
When s <θ), k which is the reciprocal of the steering angle θ multiplied by a coefficient k
3. The electric bicycle according to claim 2, wherein the steering assistance function is multiplied by a steering angle function represented by / θ to calculate the steering assistance power. 5. The control unit increases the coefficient k substantially in proportion to the vehicle speed when traveling at a low speed, and sets the coefficient k to 1 when the cruise speed is exceeded. The electric bicycle according to any one of 1. 6. The steering angle sensor includes a pulser ring made of a magnetic material assembled to a handle stem, a pair of Hall elements that generate pulses having different phases as the pulser ring passes, and an output of the pair of Hall elements. The electric bicycle according to claim 1, further comprising: an up-down counter that performs up-counting or down-counting based on the output and outputs an absolute rotation position of the pulser ring. 7. The electric bicycle according to claim 1, wherein the rudder angle sensor is a potentiometer having a variable resistance whose resistance value changes in accordance with the rotation of the steering wheel stem.