JP4365113B2 - Auxiliary force control device for electric auxiliary vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrically assisted vehicle including a human power drive system and an auxiliary power drive system, and more particularly, vehicle running stability when the auxiliary power drive system is configured to supply auxiliary power to front wheels, and It relates to the improvement of start performance.
[0002]
[Prior art]
Conventionally, a human-powered drive system that supplies a driver with a pedaling force applied to a pedal by a driver, an auxiliary force drive system that generates an auxiliary force corresponding to the pedaling force in an electric motor, and supplies the auxiliary force to the driving wheel, The electric auxiliary vehicle provided with is put into practical use (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-248378 and this type of electric auxiliary vehicle may be configured such that the auxiliary force drive system supplies auxiliary force to the front wheels.
[0004]
[Problems to be solved by the invention]
However, when the auxiliary force is supplied to the front wheels as described above, the front wheels are likely to slip on a road surface with a low coefficient of friction, such as when it rains, and the running stability and start performance of the vehicle, particularly climbing start performance on a slope. However, there is not enough, and improvement in this respect is required.
[0005]
The present invention has been made in view of the above-described conventional situation, and when the auxiliary force drive system is configured to supply the auxiliary force to the front wheels, the electric drive that can improve the running stability and start performance of the vehicle. An object is to provide an auxiliary force control device for an auxiliary vehicle.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is a human-powered drive system that supplies a pedal force applied to a pedal to a rear wheel, and an auxiliary force drive system that supplies an auxiliary force at a predetermined auxiliary ratio to the pedal force from an electric motor to a front wheel. An auxiliary force control device for an electric assist bicycle comprising : slip detecting means for detecting the occurrence of slip on the front wheel; and, when the occurrence of slip is detected, the assist ratio in the assist force drive system is reduced, and the reduced assist An auxiliary ratio control means for holding the ratio for a predetermined time and then gradually increasing it to return to the original auxiliary ratio is provided.
[0007]
According to a second aspect of the present invention, in the first aspect, the slip detection means determines that the front wheel slips when the front wheel speed is greater than a predetermined value by a predetermined value.
[0008]
According to a third aspect of the present invention, in the first aspect, the slip detection means is coasting when the front wheel speed determined from the rotational speed of the electric motor when a predetermined time elapses from the start of supplying the auxiliary force is equal to or greater than a predetermined value. If it is less than a predetermined value, it is determined that the vehicle has started after the vehicle is stopped. After determining that the vehicle has started, the rate of increase in the front wheel vehicle speed obtained from the rotational speed of the electric motor is predetermined. It is characterized in that it is determined that the front wheel is slipping when the value is higher than the value.
[0009]
[Effects of the invention]
According to the first aspect of the present invention, when the front wheel is detected to be slipping, the assisting ratio in the assisting force drive system is reduced, so that the front wheel slip can be immediately released and when the slip is released gradually. since it returned to the original auxiliary ratio can supply auxiliary power to the front wheels. Therefore, it is possible to improve the running stability by avoiding the slip of the front wheel, and also to supply the auxiliary force to the front wheel while avoiding the slip even at the time of starting, and in particular, the starting performance in starting on the hill can be improved.
[0010]
According to the invention of claim 2, since it is determined that the front wheel slip has occurred when the front wheel rotational speed is greater than the rear wheel rotational speed by a predetermined value or more, the front wheel slip is easily and reliably generated. Can be detected.
[0011]
According to a third aspect of the present invention, when the front wheel speed due to the rotational speed of the electric motor is equal to or higher than a predetermined value after a predetermined time has elapsed since the start of the supply of auxiliary force, it is determined that the vehicle is in a re-accelerated state from coasting. Therefore, when the occurrence of slip is determined based on the motor rotation speed, it is possible to prevent re-acceleration from being erroneously recognized as the occurrence of slip.
[0012]
If it is less than the predetermined value, it is determined that the vehicle is in a starting state since the vehicle is stopped. In this starting state, the front wheel slips when the increase rate of the front wheel speed determined from the rotational speed of the electric motor is greater than or equal to the predetermined value. Therefore, the occurrence of slip can be detected based on the rotational speed of the electric motor.For example, the front wheel speed and the rear wheel speed can be respectively obtained and compared with a method of detecting the occurrence of slip based on the difference between the two vehicle speeds. The configuration is simple and the wheel speed detection sensor is unnecessary, so that the cost can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1-4 is a figure for demonstrating 1st Embodiment of this invention, FIG. 1 is a side view of the electrically-assisted bicycle which mounts the auxiliary force control apparatus by this embodiment, FIG. 2 is auxiliary force control apparatus. FIG. 3 is a flowchart for explaining the control operation, and FIG. 4 is a characteristic diagram showing the auxiliary ratio when slip occurs.
[0014]
In FIG. 1, reference numeral 1 denotes an electrically assisted bicycle as an electrically assisted vehicle, and a body frame 2 of the body assisted bicycle 2 includes a head pipe 3, a down tube 4 extending obliquely downward from the head pipe 3 toward the rear of the vehicle body, and a rear of the down tube 4. A seat tube 5 extending upright from the end, a pair of left and right chain stays 6 extending substantially horizontally rearward from the vicinity of the lower end of the seat tube 5, the rear ends of both chain stays 6 and the seat tube 5 and a pair of left and right seat stays 7 that are coupled to the upper part of the seat 5.
[0015]
A front fork 8 is pivotally supported on the head pipe 3 so as to be rotatable left and right. A front wheel 9 is pivotally supported at the lower end of the front fork 8, and a steering handle 10 is fixed to the upper end. A saddle 11 is attached to the upper end of the seat tube 5. Further, a rear wheel 12 is pivotally supported at the rear end of the chain stay 6.
[0016]
The battery-assisted bicycle 1 according to the present embodiment includes a human-power drive system 13 that supplies a pedal force applied to a pedal 15b by a driver to a rear wheel (drive wheel) 12 through a predetermined gear ratio, and an electric power system corresponding to the pedal force. And an auxiliary force drive system 14 for supplying auxiliary force from the motor 18 to the front wheels 9.
[0017]
The human power drive system 13 has the following configuration. A crank arm 15a is fixed to both ends of a pedal shaft 15 disposed in the vehicle lower end direction at the center lower end portion of the vehicle body frame 2, and a pedal 15b is pivotally supported at the tip of the crank arm 15a.
[0018]
A large-diameter drive sprocket 15c mounted inside the right crank arm 15a of the pedal shaft 15 and a small-diameter driven sprocket 16a mounted on the input shaft in the rear wheel hub 16 of the rear wheel 12 are connected by a chain 17. Has been. As a result, the speed increasing mechanism 19 is configured to increase the speed of the rotation of the pedal shaft 15 by the driver's pedaling force according to the gear ratio of the drive and driven sprockets 15c and 16a and transmit it to the rear wheel side.
[0019]
A pedal force sensor 20 for detecting a pedal force (torque) input to the pedal 15b by the driver is disposed between the pedal shaft 15 and the drive sprocket 15c. Specifically, the pedal shaft 15 and the drive sprocket 15c are biased by a spring or the like so as to be relatively rotatable in a predetermined angle range and in which the relative rotation is zero, that is, the relative rotation angle increases as the pedal effort increases. Are connected to increase. The magnitude of the relative rotation angle is detected as the pedal effort.
[0020]
Specifically, for example, a voltage proportional to the relative rotation angle is output by a potentiometer. Here, since the waveform of this voltage is a substantially sine waveform that forms one cycle for each rotation of the pedal shaft 15, the rotational speed of the pedal shaft 15 can be obtained by measuring the period of this voltage waveform.
[0021]
Further, a three-speed transmission mechanism 21 is built in the rear wheel hub 16, and the transmission mechanism rotates the input shaft in the rear wheel hub 16 from any one of the first to third speeds. And is transmitted to the output shaft in the rear wheel hub 16. The rotation of the output shaft is transmitted to the rear wheel 12 via the one-way clutch 22.
[0022]
The auxiliary force drive system 14 includes a battery unit 23 disposed between the seat stay 5 and the front edge of the rear wheel 12, and an auxiliary force unit built in the front wheel hub 27. This auxiliary force unit is configured to decelerate the rotation of the electric motor 18 disposed in the front wheel hub 27 by the speed reduction mechanism 24 and transmit it to the front wheel 9 via the one-way clutch 25.
[0023]
The battery unit 23 incorporates a large number of rechargeable batteries and a controller 26 that controls the output by applying voltage and applied current to the electric motor 18. The controller 26 calculates a necessary auxiliary force by multiplying the pedaling force by a reference auxiliary ratio, and controls an applied voltage and an applied current to the electric motor 18 so as to obtain the auxiliary force.
[0024]
The controller 26 obtains a human-powered vehicle speed (rear wheel vehicle speed) Vm from a pedaling force detection value (voltage waveform) input from the pedaling force sensor 20 of the human-powered driving system 13, and a motor input from the auxiliary-power driving system 14. The auxiliary vehicle speed (front wheel speed) Vp is obtained from the voltage, current, etc., and when the front wheel speed Vp is larger than the rear wheel speed Vm by a predetermined value or more, it is determined that slip has occurred in the front wheels 9, and the reference auxiliary ratio Is corrected to a smaller slip assist ratio, and the electric motor 18 generates an assist force obtained by multiplying the slip assist ratio by the detected pedaling force.
[0025]
The control operation of the auxiliary force control device by the controller will be described in further detail with reference to the flowchart of FIG. When the assist force control flow is started, when the slip process is not being performed, that is, when the slip process flag is not set (step S1), the front wheel vehicle speed is compared with the rear wheel vehicle speed, and the front wheel vehicle speed is set to a predetermined speed from the rear wheel vehicle speed. If it is greater than (for example, 2 km / h) (step S2), it is determined that slip of the front wheels has occurred, the flag during the auxiliary ratio reduction process is set, and the auxiliary ratio reduction process is started (step S3). .
[0026]
In the assist ratio lowering process, the assist force is obtained by multiplying the detected pedal force by the assist ratio obtained from the slip assist ratio characteristic line A or B shown in FIG. The slip auxiliary ratio characteristic line A keeps decreasing to about 5% of the normal reference auxiliary ratio for a certain time (for example, 0.2 seconds) from the time of slip detection (at the start of the auxiliary ratio lowering process), and then gradually increases, It is set to recover to about 80% when a certain time (for example, 0.4 seconds) elapses from the start of the auxiliary ratio reduction process. In the characteristic line B, the auxiliary ratio is started to increase earlier from the time of slip detection. The auxiliary ratio lowering process ends after the fixed time has elapsed, and the auxiliary ratio lowering process flag is cleared (steps S4 and S5).
[0027]
Thus, in the first embodiment, when it is detected that the front wheel 9 is slipping, the assist ratio in the assist force drive system is greatly reduced, so that the slip of the front wheel 9 can be immediately released. When the slip is released, the reference auxiliary ratio is gradually returned, so that the auxiliary force can be immediately supplied to the front wheel 9 as the slip is released. Therefore, it is possible to improve the running stability by avoiding the slip of the front wheel 9, and also to supply the auxiliary force to the front wheel 9 while avoiding the slip even at the time of starting, and in particular, the starting performance in starting on the hill can be improved.
[0028]
Further, since it is determined that the front wheel 9 is slipping when the front wheel speed Vp is higher than the rear wheel speed Vm by a predetermined value or more, the occurrence of the slip of the front wheel 9 can be detected easily and reliably.
[0029]
FIGS. 4 to 6 are diagrams for explaining a second embodiment of the present invention, FIG. 5 is a flowchart, and FIG. 6 is a vehicle speed-time characteristic diagram for explaining distinction detection between reacceleration and start. It is.
[0030]
In the second embodiment, it is determined that a slip has occurred when the increase rate of the front wheel vehicle speed obtained from the rotational speed of the electric motor is equal to or greater than a predetermined value. On the other hand, for example, if the driver stops pedaling and travels inertially when traveling on a flat road, the supply of the auxiliary force is stopped, and thus the rotation of the electric motor is also stopped. Then, when shifting to the reacceleration state in which the pedal is started again from this state, the electric motor starts to rotate to generate an assisting force corresponding to the pedal depression force in this case. In this case, the rate of change of the rotational speed is Usually, it exceeds a predetermined value, and therefore there is a concern that it is erroneously recognized as occurrence of slip.
[0031]
Therefore, in the second embodiment, when the vehicle speed obtained from the rotation speed of the electric motor is a predetermined speed (for example, (4 km / h) or more after a predetermined time (for example, 0.3 seconds) has elapsed since the start of supplying the auxiliary force. Is determined to be in a re-accelerated state, and it is not determined that slip has occurred.
[0032]
When the vehicle speed is less than the predetermined speed, it is determined that the vehicle is in a starting state, and after a certain period of time has elapsed, the rate of increase in vehicle speed obtained from the rotational speed of the electric motor is greater than or equal to a certain value. Determines that a slip of the front wheel 9 has occurred.
[0033]
The control operation will be further described in detail with reference to FIG. When a predetermined time (for example, 0.3 seconds) has elapsed since the start of the auxiliary force supply (step S11), when the front wheel speed determined from the motor rotation speed at that time is equal to or higher than the predetermined speed (for example, 4 km / h) (step In S12), it is determined that the vehicle is in the reacceleration state (see FIG. 6), the start flag is cleared (step S22), and the process ends.
[0034]
On the other hand, if the front wheel speed is less than the predetermined speed in step S12, it is determined that the vehicle is in a starting state, and a starting flag is set (step S14). In step S11, when 0.3 second has not elapsed since the start of the auxiliary force supply, the process proceeds to step S19, and when a sufficient time, for example, 3 seconds elapses from the start of the auxiliary force supply, the start state is set. A start flag is set (steps S20 and S21), and then the process proceeds to step S14.
[0035]
In step S14, when slip processing is not being performed, that is, when the slip processing flag is not set, increase / decrease of the front wheel vehicle speed is obtained every predetermined time (for example, 50 ms), and the increase rate of the front wheel vehicle speed every 50 ms is a predetermined value. It is determined whether or not (for example, +0.8 km / h) or more (step S15). If the vehicle speed increase rate is equal to or greater than the predetermined value, it is determined that slip has occurred in the front wheel 9, the slip processing flag is set, and the assist ratio decreases along the slip assist ratio characteristic line A or B in FIG. Processing is performed (step S16). When a predetermined time elapses from the start of the auxiliary ratio reduction process, the auxiliary ratio reduction process ends, the slip processing flag is cleared (step S17), and the process ends.
[0036]
According to the second embodiment, the vehicle speed of the front wheel 9 is obtained based on the rotation speed of the electric motor, and it is determined that the front wheel is slipping when the increase rate of the front wheel vehicle speed is equal to or greater than a predetermined value. Therefore, for example, the front wheel speed and the rear wheel speed are obtained separately by a rotational speed sensor, etc., and the configuration is simpler than the method of detecting the occurrence of slip based on the difference between both speeds, and the wheel speed detection sensor is unnecessary. Cost can be reduced.
[0037]
Then, when the front wheel speed determined from the rotational speed of the electric motor at the time when the auxiliary power supply is started exceeds a predetermined value, it is determined that the vehicle is reaccelerated from inertial running. When the occurrence of slip is determined based on the speed, it is possible to prevent erroneous recognition of re-acceleration as occurrence of slip.
[0038]
Further, when the front wheel speed is less than a predetermined value, it is determined that the vehicle is in a starting state from the stop of the vehicle. Since it is determined that the front wheels are slipping when the increase amount of the vehicle speed per predetermined time is equal to or greater than a predetermined value, the occurrence of slip can be reliably detected based on the rotational speed of the electric motor.
[Brief description of the drawings]
FIG. 1 is a side view of a battery-assisted bicycle including an auxiliary force control device according to a first embodiment of the present invention.
FIG. 2 is a block diagram of the auxiliary force control device.
FIG. 3 is a flowchart for explaining a control operation of the control device.
FIG. 4 is a characteristic diagram showing an auxiliary ratio characteristic in the auxiliary force control device.
FIG. 5 is a flowchart for explaining a control operation of the auxiliary force control apparatus according to the second embodiment of the present invention.
FIG. 6 is a vehicle speed change diagram for distinguishing between reacceleration and start in the second embodiment device;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electric auxiliary bicycle 9 Front wheel 13 Human power drive system 14 Auxiliary force drive system 15 Pedal 18 Electric motor 26 Controller (slip detection means, auxiliary ratio control means)

Claims (3)

An electrically assisted bicycle equipped with a human-powered drive system that supplies a pedal force applied to a pedal to a rear wheel and an auxiliary force drive system that supplies an auxiliary force with a predetermined auxiliary ratio to the pedal force from an electric motor to a front wheel. In the auxiliary force control device, slip detection means for detecting the occurrence of slip on the front wheels, and when the occurrence of slip is detected, the auxiliary ratio in the auxiliary force drive system is reduced and the reduced auxiliary ratio is held for a predetermined time. An assisting force control device for a battery-assisted bicycle , further comprising assisting ratio control means that gradually increases and then returns to the original assisting ratio. 2. The assisting force control apparatus for a battery-assisted bicycle according to claim 1, wherein the slip detection means determines that the front wheel slips when the front wheel speed is greater than a predetermined value by a predetermined value. 2. The slip detection means according to claim 1, wherein the front wheel speed determined from the rotational speed of the electric motor when a predetermined time elapses from the start of supplying the auxiliary force is determined to be a reacceleration state from inertial running when the front wheel vehicle speed is equal to or higher than a predetermined value. If it is less than the predetermined value, it is determined that the vehicle is in a starting state since the vehicle is stopped, and after determining that the vehicle is in the starting state, the front wheel slips when the increase rate of the front wheel speed determined from the rotational speed of the electric motor is equal to or greater than the predetermined value An assisting force control device for a battery-assisted bicycle , characterized in that it is determined that

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