JP2004243920A - Auxiliary power control device for motor-assisted vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auxiliary power control device for a motor-assisted vehicle capable of obtaining sufficient auxiliary power regardless of gear shifting stages, when a human-powered drive system is provided with a transmission mechanism. <P>SOLUTION: The auxiliary power control device for the motor-assisted vehicle 1 comprises the human-powered drive system 13 supplying treading power added on a pedal 15b to drive wheels 12 through a specified transmission ratio, and an auxiliary power drive system 14 supplying auxiliary power from an electric motor corresponding to the treading power to the drive wheels 12. An auxiliary power correcting means 26 for correcting the auxiliary power corresponding to the treading power on the basis of a transmission ratio at the present time is provided, and the corrected auxiliary power is supplied from the motor to the drive wheels 12. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric assist vehicle provided with a human-powered driving system and an auxiliary-power driving system, and more particularly, to an improvement in a method of setting an auxiliary ratio with respect to a pedaling force when the human-powered driving system includes a transmission mechanism.
[0002]
[Prior art]
Conventionally, a human-powered driving system that supplies a pedaling force applied to a pedal to a driving wheel by a driver, and an auxiliary-powered driving system that generates an auxiliary force corresponding to the pedaling force to an electric motor and supplies the auxiliary force to the driving wheel. An electric assist vehicle equipped with a vehicle has been put to practical use. There is an electric assist vehicle of this type in which a speed change mechanism is provided in the middle of the above-mentioned manual drive system (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-105155 A
[Problems to be solved by the invention]
However, in the above-described conventional electric assist vehicle with a speed change mechanism, the driver may feel that the assisting force or assist ratio is insufficient, especially when traveling at a low speed. This is considered for the following reasons.
[0005]
In this type of electric assist vehicle, when the vehicle speed is equal to or less than a prescribed value (for example, 15 km / h), the pedaling force by the driver pedaling (more precisely, the power by a person = the pedaling force (torque) × rotation speed) In general, an assisting power of 1.0 (more precisely, motor assisting power = motor torque × rotational speed) is supplied from an electric motor.
[0006]
However, the above-described conventional electric assist vehicle with a speed change mechanism is configured such that, regardless of the speed, the electric motor simply outputs an assist force obtained by multiplying the pedal depression force (torque) at that time by a constant assist ratio. Have been.
[0007]
On the other hand, in the case of a vehicle with a speed change mechanism, if the running resistance is the same, the required pedaling force (torque) decreases as the speed decreases. Therefore, at low speeds, as the pedaling force decreases, the assisting force also decreases, and eventually the necessary motor assisting force cannot be obtained. In other words, in the electric assist vehicle with the transmission mechanism, for example, when the assist ratio is set to 1.0 in the high speed stage, the assist ratio becomes smaller than 1.0 in the low speed stage.
[0008]
The present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the problem described above. When a human-powered driving system includes a speed change mechanism, an assisting method for an electric assist vehicle that can obtain a sufficient assist force regardless of the gear position. It is an object to provide a force control device.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a human-powered driving system that supplies a pedaling force applied to a pedal to driving wheels through a predetermined gear ratio, and an auxiliary force that supplies an auxiliary force from an electric motor according to the pedaling force to the driving wheels. An assisting force control device for an electrically assisted vehicle having a driving system, comprising: an assisting force correcting means for correcting an assisting force corresponding to the pedaling force based on a current gear ratio; and transmitting the corrected assisting force to the motor. , And is supplied to the drive wheels.
[0010]
According to a second aspect of the present invention, in the first aspect, the auxiliary force drive system generates an auxiliary force having a magnitude corresponding to the pedaling force by supplying an auxiliary current having a magnitude corresponding to the pedaling force to the electric motor. The auxiliary force correction means is configured to reduce the auxiliary current from the auxiliary current corresponding to the pedaling force as the vehicle speed ratio ε (= Vm / Vp) of the human-powered vehicle speed Vm to the auxiliary power-based vehicle speed Vp increases. It is characterized in that it is corrected so as to increase.
[0011]
According to a third aspect of the present invention, in the first or second aspect, the human-powered vehicle speed is obtained by a rotation speed of a pedal shaft or by a cycle of a pedal depression force, and the auxiliary power system vehicle speed is obtained by a rotation speed of a motor shaft. Alternatively, it is obtained by the current and voltage applied to the electric motor.
[0012]
Here, when the human-powered vehicle speed is obtained from the rotation speed of the pedal shaft, and when the auxiliary power-based vehicle speed is obtained from the rotation speed of the motor shaft, a rotation sensor for obtaining the rotation speed is attached to the pedal shaft and the motor shaft. . On the other hand, when the human-powered vehicle speed is obtained by the cycle of the pedaling force and when the auxiliary power-based vehicle speed is obtained by the motor applied voltage and current, the vehicle speed detection sensor itself becomes unnecessary.
[0013]
A fourth aspect of the present invention is characterized in that, in the first aspect, the auxiliary force correction means directly detects a current gear position and corrects the auxiliary force with a gear ratio according to the gear position.
[0014]
Operation and Effect of the Invention
According to the first aspect of the present invention, the assisting force that is obtained by correcting the assisting force according to the treading force based on the current gear ratio is supplied to the drive wheels. By increasing the assist ratio as compared with the case of the high-speed gear, it is possible to make the correction assist force (torque) larger than the assist force according to the actual pedaling force (torque). It is possible to avoid problems such as feeling that the auxiliary rate is insufficient.
[0015]
More specifically, it is as follows. In the case of an electric assist vehicle with a speed change mechanism, if the traveling speed and traveling resistance are the same, the required pedaling force decreases as the gear speed decreases, but the rotational speed increases. Therefore, the power (pedal force (torque) × rotational speed) generated by a person due to the pedaling force ) Is the same as for the high speed stage. In the conventional vehicle, the assist force according to the reduced pedaling force is output as it is, so the driver feels that the assist force is insufficient. On the other hand, in the present invention, the auxiliary force is corrected so as to correspond to the high rotation speed by considering the gear ratio, so that the shortage of the auxiliary force can be avoided.
[0016]
According to the invention of claim 2, as the vehicle speed ratio ε (= Vm / Vp) of the human-powered vehicle speed Vm to the auxiliary power-based vehicle speed Vp increases, the auxiliary current supplied to the electric motor becomes larger than the auxiliary current corresponding to the pedaling force. As described above, the auxiliary force corresponding to the pedaling force is corrected to a larger value in the lower gear, and the problem of insufficient assist force in the lower gear can be avoided.
[0017]
Further, since the vehicle speed ratio between the human-powered vehicle speed obtained from the human-powered drive system and the auxiliary power-based vehicle speed obtained from the auxiliary power drive system, that is, the current gear ratio, is obtained, the current gear position is directly detected. There is no need to provide a sensor, and the problem of insufficient auxiliary power can be avoided at low cost. In addition, since this type of electric assist vehicle conventionally detects the human-powered vehicle speed and the auxiliary power-based vehicle speed because of the need for the assisting force control, this detection data can be used, and the vehicle speed detecting sensor is newly added. No need to add.
[0018]
According to the third aspect of the present invention, the human power supply system vehicle speed is obtained by the rotation speed of the pedal shaft or by the cycle of the pedal depression force, and the auxiliary power system vehicle speed is applied by the rotation speed of the motor shaft or to the electric motor. Since the voltage and the current are determined, the vehicle speed of the human power system and the vehicle speed of the auxiliary power system can be easily obtained with a simple structure.
[0019]
According to the fourth aspect of the present invention, the present speed stage is detected, and the auxiliary force is corrected with a speed ratio corresponding to the current speed stage. By making the assist ratio larger than the above, it is possible to make the assist force (torque) larger than the pedaling force (torque), and it is possible to avoid the problem that the assist force becomes insufficient depending on the gear position.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 3 are views for explaining an embodiment of the present invention. FIG. 1 is a side view of an electric assist bicycle equipped with an assist force control device according to the embodiment, and FIG. FIG. 3 is a block diagram and FIG. 3 is a flowchart for explaining the control operation.
[0021]
In FIG. 1, reference numeral 1 denotes an electric assisted bicycle as an electric assisted vehicle, which has a body frame 2, a head pipe 3, a down tube 4 extending obliquely downward from the head pipe 3 to the rear of the vehicle, and a rear tube 4. A seat tube 5 extending upright from an end, a pair of left and right chain stays 6 extending substantially horizontally rearward from near the lower end of the seat tube 5, a rear end portion of both chain stays 6, and the seat tube 5 is provided with a pair of left and right seat stays 7 which are connected to the upper part of the seat stay 5.
[0022]
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 mounted on the upper end of the seat tube 5. Further, a rear wheel 12 is supported at the rear end of the chain stay 6.
[0023]
The electric assist bicycle 1 of the present embodiment includes a human-powered driving system 13 that supplies a pedaling force applied to the pedal 15b by a driver to a rear wheel (driving wheel) 12 via a predetermined gear ratio, and an electric motor corresponding to the pedaling force. An auxiliary force drive system 14 that supplies the auxiliary force from the motor 18 to the rear wheel 12 is provided.
[0024]
The manual drive system 13 has the following configuration. Crank arms 15a are fixed to both ends of a pedal shaft 15 arranged at the center lower end of the body frame 2 in the vehicle width direction, and a pedal 15b is pivotally supported at the tip of the crank arm 15a.
[0025]
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. Have been. Thus, a speed increasing mechanism 19 is configured to increase the speed of rotation of the pedal shaft 15 due to the pedaling force of the driver in accordance with the tooth ratio of the driving and driven sprockets 15c and 16a and transmit the rotation to the rear wheels.
[0026]
A pedaling force sensor 20 for detecting a pedaling force (torque) input to the pedal 15b by the driver is provided between the pedal shaft 15 and the driving sprocket 15c. Specifically, the pedal shaft 15 and the driving sprocket 15c are relatively rotatable within a predetermined angle range and are urged by a spring or the like in a direction where the relative rotation is set to 0, that is, the relative rotation angle increases as the pedaling force increases. Are connected so as to increase. Then, the magnitude of the relative rotation angle is detected as the pedaling force.
[0027]
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 rotation speed of the pedal shaft 15 can be obtained by measuring the cycle of this voltage waveform.
[0028]
Further, a three-speed transmission type speed change mechanism 21 is built in the rear wheel hub 16, and the speed change mechanism rotates the input shaft in the rear wheel hub 16 in any one of first to third speeds. And the power 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.
[0029]
Here, the speed ratios of the first speed, the second speed, and the third speed of the speed change mechanism 21 are 2.0, 1.33, and 1.0 when the speed increase ratio of the speed increase mechanism 19 is included. Is set. Here, the gear ratio of 2.0 means that the rear wheel makes one revolution for every two revolutions of the pedal shaft.
[0030]
The auxiliary power 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 power unit disposed in the rear wheel hub 16. . The auxiliary force unit is configured to reduce the rotation of the electric motor 18 disposed in the rear wheel hub 16 by the reduction mechanism 24 and transmit the rotation to the rear wheel 12 via the one-way clutch 25.
[0031]
In the battery unit 23, a number of rechargeable batteries and a controller 26 for controlling the output by applying voltage and current to the electric motor 18 are incorporated. The controller 26 functions as an auxiliary force correction unit that corrects the auxiliary force corresponding to the pedaling force based on the current gear ratio. That is, the human-powered vehicle speed Vm is determined from the treading force detection value (voltage waveform) input from the treading force sensor 20 of the human-powered driving system 13, and the auxiliary power-system vehicle speed is determined from the motor voltage, current, etc. input from the auxiliary power driving system 14. Vp is obtained, the current gear ratio is estimated from the ratio between the two vehicle speeds Vm and Vp by a method described later, and the assisting force corresponding to the pedaling force is corrected based on the estimated gear ratio.
[0032]
Specifically, it is obtained by multiplying the auxiliary current Io having a magnitude corresponding to the pedaling force by a larger correction coefficient as the vehicle speed ratio ε (= Vm / Vp) of the human-powered vehicle speed Vm to the auxiliary-powered vehicle speed Vp increases. The corrected auxiliary current Io ′ is supplied to the electric motor 18.
[0033]
The control operation of the auxiliary force control device according to the present embodiment will be described in more detail with reference to the flowchart of FIG. When the assist force control flow starts, an assist force vehicle speed Vp and a human power vehicle speed Vm are obtained (steps S1 and S2).
[0034]
As described above, the auxiliary power system vehicle speed Vp determines the motor rotation speed from the voltage and current applied to the electric motor and the known motor winding resistance and the like, and multiplies the motor rotation speed by the reduction ratio of the reduction mechanism 24. It is required by
[0035]
As the human-powered vehicle speed Vm, the rotation speed of the pedal shaft 15 obtained from the cycle in the voltage waveform from the pedaling force sensor 20 as described above is employed. Note that a method described later is employed to increase the accuracy of the pedal shaft rotation speed obtained from the cycle of the voltage waveform.
[0036]
Then, the vehicle speed ratio ε, that is, the human-powered vehicle speed Vm / the auxiliary power-based vehicle speed Vp is obtained (step S3). In this case, it is determined that the higher the vehicle speed ratio ε, the lower the speed of the transmission mechanism is, and the lower the speed ratio, the higher the speed. Specifically, when the vehicle speed ratio ε is 1.0 to 1.16, it is determined to be the third speed (step S4), and when it is more than 1.16 to 1.56 or less, it is determined to be the second speed. The speed is determined to be the first speed (step S5) when the value exceeds 1.56 and is equal to or less than 2.3 (step S6).
[0037]
If the third speed, the second speed, and the first speed are determined, the auxiliary current Io corresponding to the pedal depression force is corrected to 1.0, 1.33, and 1.78 times, respectively ( Steps S7, S8, S9), the corrected auxiliary current Io 'is supplied to the electric motor 18. If the vehicle speed ratio ε does not fall in any of the above ranges, it is determined that a measurement error has occurred, and the process proceeds to step S7 where the auxiliary current Io corresponding to the pedaling force is supplied to the electric motor 18.
[0038]
As described above, the auxiliary current Io corresponding to the pedaling force is supplied to the electric motor 18 by correcting the auxiliary current Io 'based on the current vehicle speed ratio ε, that is, the gear ratio. In the case of the first gear (first speed), a larger correction auxiliary current Io 'is supplied to the electric motor 18 than in the case of the high gear (second speed and third speed). The correction assisting force (torque) larger than the assisting force can be obtained, and the problem that the assisting force is insufficient in a low-speed stage can be avoided.
[0039]
Further, the vehicle speed ratio ε between the human-powered vehicle speed Vm obtained from the human-powered drive system 13 and the auxiliary power-system vehicle speed Vp obtained from the auxiliary power drive system 14, that is, the current gear ratio is obtained. Therefore, there is no need to provide a sensor for directly detecting the shift speed in the above-described embodiment, and the problem of insufficient auxiliary power can be avoided at low cost.
[0040]
Further, the human power supply system vehicle speed Vm is obtained by the cycle of the voltage waveform from the pedaling force sensor 20 representing the pedaling force, and the auxiliary power system vehicle speed Vp is obtained by the voltage, current, etc. applied to the electric motor 18, so that the human power system The vehicle speed Vm and the auxiliary power system vehicle speed Vp can be easily obtained with a simple structure. In addition, this type of electric assist vehicle is conventionally provided with the above-described treading force sensor 20 because of the necessity of assist force control, and measures the motor applied voltage and current. Therefore, in obtaining the vehicle speeds, detection data from existing parts can be used, and there is no need to add a new sensor.
[0041]
Here, in the case of the method of obtaining the rotation speed of the pedal shaft 15 from the cycle of the output voltage waveform of the pedaling force sensor 20, the detection accuracy of the rotation speed may be low because the pedaling operation by the driver is not always constant. Therefore, in the present embodiment, when the vehicle speed ratio ε is within a certain wide range (1.0 to 1.16, 1.16 to 1.56, 1.56 to 2.3), the third speed and the second speed are set. , The first speed, the speed ratio can be accurately obtained even when the above-mentioned rowing operation by the driver is not constant, so that the correction assist force can be accurately obtained.
[0042]
In the above-described embodiment, the gear position is estimated from the vehicle speed ratio between the human-powered vehicle speed and the auxiliary power-related vehicle speed. However, the current gear position is directly detected, and the auxiliary current Io is corrected according to the gear position. Of course, this is the case, and this is the invention of claim 4.
[Brief description of the drawings]
FIG. 1 is a side view of an electric assist bicycle including an assist force control device according to an embodiment of the present invention.
FIG. 2 is a block diagram of the auxiliary force control device.
FIG. 3 is a flowchart illustrating a control operation of the control device.
[Explanation of symbols]
1 electric assist bicycle (electric assist vehicle)
12 Rear wheel (drive wheel)
13 human power drive system 14 auxiliary power drive system 15b pedal 26 controller (auxiliary power correction means)
Vm Human-powered vehicle speed Vp Auxiliary-powered vehicle speed

Claims (4)

An electric assist system including a human-powered drive system that supplies a pedal force applied to a pedal to drive wheels via a predetermined gear ratio, and an auxiliary force drive system that supplies an auxiliary force corresponding to the pedal force from an electric motor to the drive wheels. An assisting force control device for a vehicle includes an assisting force correcting means for correcting an assisting force according to the pedaling force based on a current gear ratio, and supplying the corrected assisting force from the electric motor to driving wheels. An assist power control device for an electrically assisted vehicle, characterized in that: In claim 1, the auxiliary force drive system is configured to generate an auxiliary force having a magnitude corresponding to the pedaling force by supplying an auxiliary current having a magnitude corresponding to the pedaling force to the electric motor. The auxiliary force correcting means corrects the auxiliary current so that the larger the vehicle speed ratio ε (= Vm / Vp) of the human-powered vehicle speed Vm to the auxiliary power-related vehicle speed Vp becomes, the larger the auxiliary current is, compared to the auxiliary current corresponding to the pedaling force. An auxiliary power control device for an electric auxiliary vehicle, characterized by: 3. The human-powered vehicle speed according to claim 1 or 2, wherein the human-powered vehicle speed is obtained by a rotation speed of a pedal shaft or a cycle of a pedal depression force, and the auxiliary power-based vehicle speed is obtained by a rotation speed of a motor shaft or applied to the electric motor. An assisting force control device for an electrically assisted vehicle, wherein the assisting force is determined by a current and a voltage. 2. The assisting force control device for an electrically assisted vehicle according to claim 1, wherein the assisting force correcting means directly detects a current gear position and corrects the assisting force with a gear ratio corresponding to the gear position.

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