JP2002240772A - Auxiliary power control device of power assisted vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary power control device of a power assisted vehicle allowing maintaining a specified assist ratio irrespective of a shift point in an electrically assisted vehicle with a 'detection of stepping force → speed change →resultant force' method and increasing auxiliary power when large auxiliary power is desired and decreasing the force when the large auxiliary power is not desired in the power assisted vehicle irrelevant to the arrangement of a transmission mechanism. SOLUTION: This auxiliary power control device 20 of the power assisted vehicle detects the stepping force acting on a pedal 15a in the upstream of the transmission mechanism and generates auxiliary power multiplied with the detected stepping force by the assist ratio in an electric motor for synthesizing the auxiliary power with the stepping force via the transmission mechanism to transfer it to a drive wheel 13. The assist ratio is maintained at a predetermined value irrespective of the shift point by detecting, at which speed the transmission mechanism is, and feeding a motor assisting current to the motor according to the detected point and the detected stepping force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric assist vehicle for assisting travel by transmitting assist power obtained by multiplying a pedaling force by a predetermined assist ratio to drive wheels together with the pedaling force. The present invention relates to an auxiliary power control device capable of controlling a ratio to an appropriate value.

[0002]

2. Description of the Related Art Conventionally, an electric motor generates auxiliary power obtained by multiplying a pedaling force applied to a pedal by a driver by a specified assist ratio, and transmits the auxiliary power of the electric motor and the above-mentioned pedaling force to driving wheels. In addition, electric assist vehicles such as electric assist bicycles and electric assist wheelchairs that assist driving have been put to practical use.

[0003] The assist ratio in this specification is
It means the ratio of auxiliary power / pedal force. It is stated that the assist ratio must not exceed a specified value (usually 1.0) in order to be recognized as an electric assisted bicycle according to the Road Traffic Law. If the assist ratio exceeds 1.0, the bicycle is regarded as a motorbike under the Road Traffic Law.

[0004]

In the case of an electrically assisted vehicle equipped with a speed change mechanism, if the speed change mechanism is provided downstream of the pedaling force detection unit and the resultant force unit, the assist ratio does not change regardless of the gear position. However, if a speed change mechanism is provided between the pedaling force detection unit and the resultant force unit, the assist ratio will change depending on the shift speed. Therefore, if the setting is made so as not to exceed the specified assist ratio when the gear is on the high speed side,
There is a problem that the assist ratio is unnecessarily lowered at the lower gear, and the necessary auxiliary power cannot be obtained. Conversely, if the specified assist ratio is secured in the lower gear, the assist ratio exceeds the specified value in the higher gear.

[0005] Regardless of the arrangement of the transmission mechanism as described above, in the case of a conventional electric assist vehicle, the assist ratio is fixed to a constant value (usually 1.0) when viewed at the same gear position. Regardless of how the driver pedals, the magnitude of the assist power is determined only by the magnitude of the pedaling force. For this reason, for example, there is a problem that, depending on the traveling state, a large auxiliary power is desired and a small auxiliary power is not required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and a first invention is an electric assist vehicle of the "pedal force detection → shift → combined force" system, which provides a specified assist regardless of the gear position. The second aspect of the present invention relates to an electric auxiliary vehicle independent of the arrangement of the transmission mechanism, which increases the auxiliary power when a large auxiliary power is required, and increases the auxiliary power when the auxiliary power is not so required. An object of the present invention is to provide an auxiliary power control device for an electric auxiliary vehicle that can reduce power.

[0007]

According to a first aspect of the present invention, a stepping force applied to a pedal is detected upstream of a speed change mechanism, and an auxiliary power obtained by multiplying the detected stepping force by an assist ratio is generated in an electric motor. An auxiliary power control device for an electric auxiliary vehicle, wherein the auxiliary power is transmitted to driving wheels by synthesizing the auxiliary power with a treading force passed through the transmission mechanism. The assist ratio is maintained at a predetermined value irrespective of the shift speed by supplying a motor auxiliary current according to the detected shift speed and the detected pedaling force to the electric motor. .

In the present invention, maintaining the assist ratio at a predetermined value includes not only the case where the assist ratio is the same, but also the case where the assist ratio is maintained within a predetermined width.

According to a second aspect of the present invention, in the first aspect, the motor auxiliary current in the lower gear is set to a value larger than the motor auxiliary current in the higher gear for the same pedaling force. I have.

According to a third aspect of the present invention, in the first or second aspect, a ratio between a vehicle speed (pedaling vehicle speed) obtained from the input state of the pedaling force and a vehicle speed (motor vehicle speed) obtained from the rotating state of the electric motor. Is determined based on the speed.

According to a fourth aspect of the present invention, in the third aspect, the pedaling vehicle speed is obtained based on a period from the peak of the pedaling voltage to the next peak, and the motor vehicle speed is obtained based on the induced voltage of the electric motor. Features.

According to a fifth aspect of the present invention, an electric motor generates auxiliary power obtained by multiplying an assist ratio by the detected pedal force and detects the pedal force applied to the pedal. The assisting power control device for the electrically assisted vehicle is configured to determine, based on the input state of the pedaling force, whether the emphasis is placed on assist power supply or the cruising distance emphasis on cruising distance. The assist ratio in the emphasis state is set to a value larger than the assist ratio in the cruising distance emphasis state.

According to a sixth aspect of the present invention, in the fifth aspect, when the variation range of the pedaling force voltage is maintained within a predetermined variation range for a predetermined time or more, the cruising distance is emphasized, and the variation range of the pedaling force voltage is set to a predetermined value. It is characterized in that the assist-oriented state is set until the treading force voltage exceeds the above-mentioned predetermined fluctuation width until it is maintained within the fluctuation width for a predetermined time.

A seventh aspect of the present invention is characterized in that, in the fifth or sixth aspect, when starting, the assist-oriented state is set regardless of the magnitude of the pedaling force.

[0015]

According to the first aspect of the present invention, the gear position of the speed change mechanism is detected, and a motor auxiliary current corresponding to the detected speed position and pedaling force is supplied to the electric motor. Therefore, the assist ratio can be maintained at a predetermined value at any gear. Therefore, for example, when the specified assist ratio is set in the high speed gear, the problem that the assist ratio becomes small in the low gear can be avoided.

According to the second aspect of the present invention, the motor assist current in the lower gear is set to a value larger than the motor assist current in the higher gear for the same pedaling force. , The assist ratio can be set to a predetermined value, and the motor auxiliary current can be set to the predetermined value even in the lower gear. The ratio of the motor assisting power to the pedaling force can be the same at both the shift speed and the low speed shift speed, and a predetermined assist ratio can be maintained.

According to the third aspect of the present invention, the shift speed is determined based on the ratio between the pedaling force vehicle speed determined from the input state of the pedaling force and the motor vehicle speed determined from the rotation state of the electric motor. The shift speed can be detected with a simpler configuration than when a sensor for mechanically detecting the speed is provided.

According to the fourth aspect of the present invention, the pedaling vehicle speed is obtained based on the cycle from the peak of the pedaling voltage to the next peak, and the motor vehicle speed is obtained based on the back electromotive voltage of the electric motor. It is possible to obtain the pedaling vehicle speed and the motor vehicle speed with a simple configuration.

According to the fifth aspect of the present invention, it is determined whether the emphasis on assist or the cruising distance is important based on the input state of the pedaling force, and the assist ratio in the emphasis on assist is set to a value larger than the assist ratio in the emphasis on cruising distance. Because a large auxiliary power can be supplied when large auxiliary power is required, such as on a slope, traveling is easy, and when a small auxiliary power is required, such as on a flat road, a small auxiliary power can be used. The cruising distance in one charge of the battery can be extended.

According to the sixth aspect of the invention, when the fluctuation range of the tread force voltage is maintained within the predetermined fluctuation range for a predetermined time or more, the cruising distance is emphasized, and the fluctuation range of the tread force voltage is within the predetermined fluctuation range. Until a predetermined time is held and when the predetermined fluctuation range is exceeded, the assist-oriented state is set. Therefore, any one of the above-described methods is used with the fluctuation of the pedal force originally detected without the need for a special sensor. It is possible to determine whether the state is the state, and there is almost no increase in cost and structural complexity.

According to the seventh aspect of the present invention, since the assist-oriented state is set at the start regardless of the magnitude of the pedaling force, the assist force is not insufficient at the start and the start is easy.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 6 are views for explaining a first embodiment according to the first to fourth aspects of the present invention. FIG. 1 is a schematic side view of an electric assist bicycle equipped with the present embodiment device, and FIG. FIG. 3 is a characteristic diagram of a pedaling force vehicle speed-motor vehicle speed characteristic, FIG. 4 is a characteristic diagram of a pedaling force voltage-motor current command value characteristic, FIG. 5 is a characteristic diagram of a pedaling force-motor auxiliary power, and FIG. 9 is a flowchart illustrating a ratio correction operation.

In FIG. 1, reference numeral 1 denotes an electric assisted bicycle as an electric assisted vehicle. A vehicle body frame 2 has a head pipe 3, a down tube 4 extending obliquely downward from the head pipe 3 to the rear of the vehicle, and a down tube. A seat tube 5 extending upward from the rear end of the down tube 4; a pair of left and right chain stays 6 extending substantially horizontally rearward from the rear end of the down tube 4; The left connecting the upper end of the seat tube 5
The vehicle includes a right pair of seat stays 7 and a horizontal tube 8 extending horizontally from the head pipe 3.

A front fork 9 is supported on the head pipe 3 so as to be rotatable left and right. A front wheel 10 is pivotally supported at the lower end of the front fork 9, and a steering handle 11 is fixed to the upper end. A saddle 12 is attached to the upper end of the seat tube 5. Further, a rear wheel 13 is pivotally supported at the rear end of the chain stay 6.

A pedal unit 14 is provided at a lower center portion of the body frame 2. The pedal unit 14 rotationally drives a crankshaft 15c via a crank arm 15b by a pedaling force applied to a pedal 15a by a driver, and transmits the rotation of the crankshaft 15c to a chain 16a.
Output. This output is transmitted to the hub via a transmission mechanism provided in the hub 18 of the rear wheel 13 and a one-way clutch downstream of the transmission mechanism.

In this embodiment, a two-stage speed change mechanism having a first speed and a second speed is used as the speed change mechanism. It is needless to say that the present invention is not limited to the two-stage speed change type, but may have three or more speed stages. When the driver turns the switching lever 11a disposed on the steering handle 11, any one of the shift speeds is selected. When the first speed is selected, the rotation of the driven sprocket to which the chain 16 is connected is output to the rear wheels as it is, and in the case of the second speed, the rotation of the driven sprocket is increased to 1.415 times ( Output to the rear wheels). It should be noted that the gear ratio is not limited to the above example.

In the pedal unit 14, a pedal force sensor 17 for continuously detecting the pedal force applied to the pedal 15a is provided. The tread force sensor 17 generates a tread force voltage proportional to the magnitude of the tread force.

An electric motor is mounted coaxially with the hub 18 of the rear wheel 13. This electric motor is
An auxiliary power corresponding to a motor auxiliary current value supplied from the battery 19 is generated. The auxiliary power and the pedaling force after passing through the transmission mechanism are respectively combined via one-way clutches to drive the hub 18 and thus the rear wheel 13.

In FIG. 2, reference numeral 20 denotes a controller, which detects which shift speed the transmission mechanism is in, and outputs a motor auxiliary current corresponding to the detected shift speed and the magnitude of the detected pedaling force. Is supplied to the electric motor to function as an auxiliary power control device that maintains the assist ratio at a specified value regardless of the gear position.

The control operation of the controller 20 will be described with reference to FIGS. As shown in FIG.
First, the vehicle speed (pedaling vehicle speed) obtained from the input state of the pedaling force applied to the pedal 15a by the driver and the vehicle speed (motor vehicle speed) obtained from the rotation state of the electric motor 18 are calculated (steps S1 and S2).

More specifically, the pedal effort voltage peak value judging section 20
The peak value of the treading force voltage from the treading force sensor 17 is determined by a, the cycle is determined by the time interval from the determined peak value to the next peak value by the treading force cycle calculating unit 20b, and further the treading force vehicle speed calculating unit 20c calculates The pedaling vehicle speed is obtained from the calculated pedaling cycle.

In the motor vehicle speed calculating section 20d,
The motor induced voltage is determined from the voltage of the battery 19, the motor current value supplied to the electric motor 18 and the PWM duty ratio, and the motor vehicle speed is determined from the induced voltage.

Based on the relationship between the pedaling vehicle speed and the motor vehicle speed, based on FIG.
It is determined which of the two speeds is set (steps S3 and S4). In the case of the first speed, the first speed pedaling force voltage-motor current command value conversion map is used, and in the case of the second speed, the second speed is used. The second speed pedaling force voltage-motor current command value conversion map is referred to (see steps S5 and S6 in FIG. 4).

Specifically, in the gear position determination section 20e,
When the pedaling vehicle speed is set to be the same as the actual vehicle speed at the second speed, the ratio of the pedaling vehicle speed / motor vehicle speed is obtained,
If the ratio is in the range of 1.21 to 2.0 (the range hatched in FIG. 3 based on the second speed), it is determined that the speed change mechanism is in the first speed, In the case of a smaller range (range above the hatched range in FIG. 3), it is determined that the second speed is set.

If the above ratio is larger than 2.0, it is impossible in calculation, but it is determined as the second speed on the program. As will be described later, the second speed motor current command value is set smaller than the first speed motor current value.
It is possible to prevent a problem such as exceeding the prescribed assist ratio.

Subsequently, in the reference map determination section 20f,
A map corresponding to the determined shift speed is selected and determined (see FIG. 4). Specifically, as shown in FIG. 4, the characteristic line A is selected for the first speed, and the characteristic line B is selected for the second speed. For example, in the case of the second speed, the characteristic line B may be referred to, and in the case of the first speed, the value of the characteristic line B may be multiplied by a magnification obtained from an experiment so that the same assist ratio is obtained. .

Further, a motor current command value calculator 20g
, A motor current command value corresponding to the tread force voltage is calculated along the reference map of FIG. 4, and a motor current corresponding to the command value is supplied to the electric motor.

As a result, as shown by the solid characteristic line A 'in FIG. 5, in any of the first speed and the second speed, the assist power becomes 1 with respect to the pedaling force 1, and the assist ratio becomes 1st speed and 1st speed. It is held at 1.0 in any of the second speeds.

Incidentally, in the case of the conventional device, the same motor current command value is employed in both the first speed and the second speed as shown by the broken line B in FIG. Therefore, as shown in FIG. 5, although the assist ratio can be set to 1.0 in the second speed, the assist ratio becomes about 0.7 in the first speed, and there is a problem that the auxiliary power is insufficient.

As described above, in this embodiment, the gear position of the speed change mechanism is detected, and the motor current command value in the first speed is set to correspond to the speed ratio of the speed change mechanism in the second speed. Therefore, the assist ratio can be maintained at the specified value (1.0) in both the first speed and the second speed. Therefore, for example, when the specified assist ratio is set in the second speed, the problem that the assist ratio decreases in the first speed can be avoided.

Further, since the gear stage is determined based on the ratio of the pedaling vehicle speed determined from the cycle from the peak of the pedaling voltage to the next peak to the motor vehicle speed determined from the induced voltage of the electric motor, the gearshift is determined. The shift speed can be detected with a simple configuration and at low cost as compared with the case where a sensor for mechanically detecting the speed is provided.

7 to 10 are views for explaining a second embodiment according to the fifth to seventh aspects of the present invention. FIG. 7 is a block diagram of an assist ratio correction based on a tread force voltage fluctuation width, and FIG. 8 is a tread force voltage. FIG. 9 is a characteristic diagram of the pedal force voltage-motor current command value according to the assist ratio correction based on the variation width, and FIG. In the drawings, the same reference numerals as those in FIGS. 1 to 6 indicate the same or corresponding parts.

The controller 20 shown in FIG. 7 is mounted on the electric assisted bicycle shown in FIG. 1, and has a function of determining a shift speed shown in FIG. 2 and outputting a motor current command value corresponding to the shift speed. It has the following functions.

As shown in FIG. 10, the controller 20 first determines whether or not a start operation is being performed on the electric assist bicycle 1 (step S11). If the start operation is being performed, the specified time (for example, 3 seconds) is determined. Until) has elapsed, the assist power importance map is referred to (step S1).
2, S13).

When the specified time has elapsed from the start, the calculation of the fluctuation range of the tread force voltage is started (step S1).
4), when the variation range of the pedaling force voltage is within the specified variation range, a cruising distance-oriented map is selected when a specified time (for example, 3 seconds) elapses (steps S15 to S17. Note that in steps S15 and S16) If the fluctuation range of the pedaling force voltage exceeds the above-mentioned specified fluctuation range and is within the specified fluctuation range, the above-mentioned assist force emphasis map is selected until a specified time elapses.

More specifically, the upper and lower limit peak value of the tread force voltage is determined by the tread force voltage upper and lower limit peak value determination unit 20h of the controller 20, and the tread force voltage fluctuation width calculator 20i is determined.
In FIG. 8A, the fluctuation range of the tread force voltage is calculated from the upper and lower limit peak values, and the reference map determination unit 20g determines that the fluctuation width of the tread force voltage obtained is a predetermined fluctuation as shown in FIG. 8A or 8B. It is determined whether it is within the width (for example, 0.6 V).

In this case, as shown in FIG. 8A, when the variation range of the tread force voltage is within the specified variation range for more than a specified time (3 seconds), the cruising distance priority state is set. It is determined that there is. When the variation width of the pedaling force voltage exceeds the above-mentioned variation width, it is determined that the assist force emphasis state is set.

Then, the motor current command value calculating section 20k calculates the motor current command value based on FIG. FIG. 9 is a map for obtaining a motor current command value corresponding to the pedaling force voltage. The characteristic lines D and D 'correspond to the case where the shift speed of the transmission mechanism is the first speed, and correspond to the assist force emphasis state and the cruising distance emphasis state, respectively. The characteristic lines E and E 'correspond to the case of the second speed, and correspond to the assist force emphasis state and the cruising distance emphasis state, respectively.

As described above, in the present embodiment, the motor current command value of the first speed is set to be larger than that of the second speed for the same pedaling force voltage. The motor current command value in the assist force emphasis state is set to be larger than that in the cruising distance emphasis state.

In the case of the characteristic lines D and E, the auxiliary power by the electric motor has the same magnitude as the pedaling force, and the assist ratio is maintained at a specified value (1.0). on the other hand,
In the case of the characteristic lines D 'and E', the auxiliary power is smaller than the pedaling force, for example, about 70%, and the assist ratio is about 0.7, which is smaller than the specified value.

When the reference map determination section 20j determines that the pedaling force input state is in the assist force emphasis state, the motor current command value is obtained along the characteristic curve D or E in FIG. When it is determined that the vehicle is in the cruising distance importance state, the motor current command value is obtained along the characteristic curve D 'or E' in FIG.

As described above, according to the present embodiment, based on the input state of the pedaling force, specifically, whether the variation width of the pedaling force voltage is within the specified variation range or has increased beyond this variation range. By judging whether the emphasis on assist or the cruising distance is important, the assist ratio in the emphasis on assist is set to a value larger than the assist ratio in the emphasis on cruising distance.
When a large auxiliary power is required, such as on a hill, a large auxiliary power can be supplied at a large assist ratio, driving is easy, and when a small auxiliary power is sufficient, such as on a flat road, a small auxiliary power is used at a small assist ratio. And one of the batteries
It is possible to extend the cruising range in each charge.

Further, it is determined whether the cruising distance is emphasized or the assist is emphasized depending on whether the variation width of the pedaling force voltage is maintained within a predetermined variation width for a predetermined time or more or exceeds a predetermined variation width. Therefore, it is possible to determine any of the above states based on the fluctuation of the pedaling force originally detected without requiring a special sensor, and there is almost no increase in cost and complicated structure.

Further, since the assist-oriented state is set at the start regardless of the magnitude of the pedaling force, the assist power is automatically obtained at a large assist ratio at the start. Is easy.

[Brief description of the drawings]

FIG. 1 is a side view of an electric assist bicycle including an assist force control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram of the auxiliary power control device.

FIG. 3 is a characteristic diagram of pedaling vehicle speed-motor vehicle speed of the control device.

FIG. 4 is a characteristic diagram of pedal force voltage-motor current command value of the control device.

FIG. 5 is a characteristic diagram of pedaling force-motor auxiliary power of the control device.

FIG. 6 is a flowchart showing an assist ratio correction operation of the control device.

FIG. 7 is a block diagram of an auxiliary power control device according to a second embodiment of the present invention.

FIG. 8 is an assist ratio correction image diagram of the control device of the second embodiment.

FIG. 9 is a characteristic diagram of a pedal effort voltage-motor current command value of the control device of the second embodiment.

FIG. 10 is a flowchart showing an assist ratio correction operation of the second control device.

[Explanation of symbols]

 Reference Signs List 1 electric assist bicycle 15a pedal 13 drive wheel 20 controller (auxiliary power control device)

Claims (7)

[Claims] 1. An electric motor generates auxiliary power obtained by multiplying an assist ratio by the detected pedaling force and detects the pedaling force applied to the pedal upstream of the speed change mechanism. In the auxiliary power control device of the electric auxiliary vehicle, which is transmitted to the drive wheels with the resultant force, the shift mechanism is detected in which shift speed, and the detected shift speed and the detected pedaling force are determined. An assist power control device for an electrically assisted vehicle, characterized in that the assist ratio is maintained at a predetermined value irrespective of a shift speed by supplying a corresponding motor assist current to the electric motor. 2. The method according to claim 1, wherein:
An auxiliary power control device for an electrically assisted vehicle, wherein a motor auxiliary current at a low speed side is set to a value larger than a motor auxiliary current at a high speed side. 3. The speed change step according to claim 1, wherein a vehicle speed (pedal force vehicle speed) determined from the input state of the pedaling force and a vehicle speed (motor vehicle speed) determined from the rotation state of the electric motor are determined. Auxiliary power control device for an electrically assisted vehicle, characterized by: 4. The electric assist according to claim 3, wherein the vehicle speed of the pedaling force is obtained based on a cycle from the peak of the pedaling voltage to the next peak, and the vehicle speed of the motor is obtained based on the induced voltage of the electric motor. Auxiliary power control device for vehicles. 5. An electric motor generates auxiliary power obtained by multiplying an assist ratio by the detected pedaling force, detecting a pedaling force applied to the pedal, and transmitting the auxiliary power to driving wheels together with the pedaling force. The assist power control device of the electrically assisted vehicle determines whether the assist-oriented state emphasizes the supply of the auxiliary power or the cruising distance-oriented state that emphasizes the cruising distance based on the input state of the pedaling force. An auxiliary power control device for an electric auxiliary vehicle, wherein the ratio is set to a value larger than an assist ratio in a cruising distance-oriented state. 6. The cruising distance emphasis state according to claim 5, wherein the variation range of the tread force voltage is maintained within a predetermined variation range for a predetermined time or more, and the variation range of the tread force voltage is set within a predetermined variation range. An assist power control device for an electrically assisted vehicle, characterized in that an assist-oriented state is set until the time is held and when the fluctuation width of the pedaling force voltage exceeds the predetermined fluctuation width. 7. The assist power control device for an electrically assisted vehicle according to claim 5, wherein the assist-oriented state is set at the time of start regardless of the magnitude of the pedaling force.