JPH04321482A - Human power driven device equipped with motor - Google Patents

Abstract

PURPOSE:To reduce exhaustion of battery in a human power driven device such as bicycle equipped with a motor by sensing the load on the human power driving system and the crank shaft rotational angle due to crank pedal, determin ing the mean load at the sensed crank angle, and controlling the output of motor with the specified conversion characteristic for the obtained mean load. CONSTITUTION:In the middle of a drive shaft, a load sensing means 30 is furnished which senses the drive torque due to human power, and the output therefrom is fed to a mean load sensing device 66. The rotational angle of a crank shaft is sensed by a crank angle sensing means 50, and the obtained value is fed to the same mean load sensing means 66. This means 66 determines the mean load on the human power driving system from these load and crank angle values. Following the stored operational program, a controller 60 determines the torque of a motor 40 with a certain specified relationship to the mean load and controls the motor 40.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a human-powered drive system with an electric motor, in which a human-powered drive system and an electric motor-based drive system are provided in parallel.

0002

[Background of the Invention] In devices driven by human power, such as bicycles, a drive device uses an electric motor in combination to reduce the load on human power when the load increases, such as when climbing a hill, while still maintaining the bicycle-like driving feeling. The applicant of the present application previously proposed (Japanese Patent Application No. 2-214947). In this proposed system, a drive system using an electric motor is provided in parallel with a human-powered drive system, and the output of the electric motor is changed in response to changes in the load on the human-powered drive system.

When a crank pedal is used for manual driving, the driving torque changes periodically depending on the rotation angle (crank angle) of the crankshaft. Therefore, the motor output also changes periodically in synchronization with the rotation of the crankshaft. When the motor output changes periodically in this way, the motor current also changes periodically, but in general, internal losses proportional to the square of the current occur in power sources such as batteries. However, it is undesirable for the current to periodically increase and decrease because it increases battery consumption.

0004

[Object of the Invention] The present invention was made in view of the above circumstances, and it is an object of the present invention to reduce the consumption of batteries used in the drive system of an electric motor, and to extend the traveling distance when this drive system is used in combination. The purpose is to provide a human power drive device with an electric motor.

[0005]

According to the present invention, the object is to provide a human-powered drive system with an electric motor in which a human-powered drive system using a crank pedal and a drive system based on an electric motor using a battery are provided in parallel. load detection means for detecting the load on the human-powered drive system; crank angle detection means for detecting the rotation angle of the crankshaft rotationally driven by the crank pedal; average load detection means for determining the average load;
This is achieved by a human power drive device with an electric motor, which is characterized by comprising a controller that controls the output of the electric motor with a predetermined conversion characteristic with respect to the detected average load.

[0006]

[Example] Fig. 1 is a block diagram showing the concept of the present invention, Fig. 2
is a diagram showing an example of application to a bicycle, FIG. 3 is an exploded view of its drive system, FIGS. 4 and 5 are diagrams showing an example of its load detection means, and FIG.
FIG. 2 is a diagram showing conversion characteristics for determining the drive torque of the electric motor from the drive torque of human power.

In FIG. 2, numeral 10 is a rear wheel which is a driving wheel, 12 is a steering front wheel, 14 is a steering handle, 16 is a seat, and 18 is a crank pedal. Pedal 18 to rear wheel 1
The human power drive system 20 (FIG. 1) that reaches 0 is formed by a crankshaft 22 that holds the pedal 18, a bevel gear 24, a drive shaft 26, and a bevel gear 28. In the middle of the drive shaft 26, there is a driving force generated by this human power, that is, a driving torque Th.
A load detecting means 30 is interposed for detecting. For example, as shown in FIG. 4, this load detection means 30 includes a shaft half 26a on the crankshaft 22 side and a shaft half 26b on the rear wheel 10 side.
torsion bar spring 32 connected to both shaft halves 26a, 26
A potentiometer (for example, a rotating sliding resistor) 34 determines the relative angle change between the two positions. Alternatively, as shown in FIG. 5, the drive shaft 26 may have a small diameter in the middle, and the torsion of the small diameter portion 26c may be detected by a strain gauge 36. The signal a of these potentiometers 34 and strain gauges 36
is removed, for example, via a slip ring (not shown).

A motor drive means 40 is provided on the drive shaft 26 between the load detection means 30 and the rear wheel 10. This motor drive means 40 includes, for example, a DC motor 42,
It includes a worm gear mechanism 44 that decelerates the rotation of the motor 42 and transmits it to the drive shaft 26, and a clutch 46 interposed between the motor 42 and the worm gear mechanism 44. This clutch 46 is composed of, for example, a one-way clutch or an electromagnetic clutch.

The rotation angle of the crankshaft 22, ie, the crank angle θ, is detected by a crank angle detection means 50. The crank angle detecting means 50 includes a gear 52 fixed to the crankshaft 22, and a light emitting element 54 and a light receiving element 56 arranged opposite to each other with the gear 52 in between. Note that two pairs of the light emitting/receiving elements 54 and 56 are provided with a phase difference of 90° with respect to the period of the teeth of the gear 52, but only one pair is shown in FIG. 3. Therefore, two light receiving elements 56
The rotational direction and rotation amount of the crankshaft 22 can be detected based on the output of the crankshaft 22 . Further, the reference angular position of the crankshaft 22 can also be detected by partially changing the spacing between the teeth of the gear 52 or by providing a notch that indicates another reference position. As a result, the absolute angle of the crank angle θ can always be detected.

Next, the controller 60 will be explained. The controller 60 is a microcomputer (hereinafter referred to as CPU).
) 62, and a ROM 64 that stores operating programs and various data. In this example, the CPU
Reference numeral 62 has the function of an average load detection means 66 for determining the average value Thm of the human-powered drive torque Th detected by the load detection means 30.

The average load detecting means 66 detects the crankshaft 22.
Torque T due to change in rotation angle, that is, crank angle θ
This eliminates the fluctuation of h. In other words, the crank angle θ(
deg), the torque Th changes periodically as shown by the solid line A in FIG. Generally, this solid line A is the torque Th
The waveform does not change much, only the amplitude changes in response to changes in . Therefore, the average load, that is, the average torque Thm can be determined by any of the following three methods.

■ θ=45°(θ1), 135°(
θ2 ), 225° (θ3 ), 215° (θ4 )
Since the torque Th at these crank angles θ1...θ4 is an intermediate value between the maximum value and the minimum value, the torque Th at these crank angles θ1...θ4 is set as the average value Thm. ■ θ=0°, 1
At 80° (θm1 and θm2, respectively), the torque Th becomes the minimum value Th (min), and when θ=90°, 27
The maximum value Th (Max
), the arithmetic mean is taken as the average value Thm. That is, Thm = [Th (min) + Th (Max)]
/2. ■ Calculate the average value Thm by integrating sample values T(θ) of torque Th taken at every small fixed angle from θ=0 to 90°, and dividing this integrated value ΣT(θ) by the number of samples n. demand. Thm=ΣT(θ)/n

Note that under operating conditions where the torque Th is extremely large, not only does the amplitude of the solid line A in FIG. 7 actually increase, but the phase of the crank angle θ also lags, as shown by the virtual line B in the figure . Therefore, taking this into consideration, the torque T
When h is large, θ1 in each method of ■ and ■ above...θ
4, θm1, θM1... may be provided with means for correcting the crank angles. Also, for method ■, the integral range (0-
90°) or may perform integration over an arbitrary range of 180°.

[0014] Since the driving torque Th caused by human power constantly changes during driving, the average value Thm within a certain cycle determined as in the above embodiment is different from the average value Thm in the next cycle. result in different values. Therefore, the average value Thm changes stepwise over time. Therefore, in order to prevent sudden changes in this average value Thm, the average value Thm
It is desirable to smooth the

Furthermore, when the rotation of the crankshaft 22 stops or becomes extremely slow, the average value Th
There is a problem that m cannot be determined or becomes inaccurate. Therefore, in such a case, that is, when the period (cycle) for calculating the average value becomes longer than the predetermined setting time,
It is desirable to change the way the average value is calculated. For example, the torque Th over a sufficiently short period of time may be integrated regardless of the crank angle to obtain an average value over that time, or the detected torque Th may be used as is without using the average value.

In this embodiment, the average load detecting means 6
6 is assumed to be held by the CPU 62 of the controller 60,
That is, although the explanation has been made as having the CPU 62 as an operating program, it is of course possible to configure it as a circuit independent from the CPU 62.

The average value Thm of the human-powered drive torque Th obtained as described above is used by the CPU 62 to determine the motor drive torque TM. That is, the CPU 62 determines the motor torque TM in accordance with the operating program stored in the ROM 64 in a predetermined relationship with respect to the average value Thm. For example, as shown by A in FIG. 6, it is possible to have a linear relationship, or as shown in B and C, the rate of increase can have a gradual decreasing or increasing characteristic.

In order to obtain these characteristics A, B, and C, for example, store these characteristics A, B, and C in the ROM 64, and calculate the motor drive torque TM to be generated when the average torque of human power drive is Thm. is read from ROM64,
A gate signal is output to supply the motor current that generates this drive torque TM.

In FIG. 2, 70 is a battery, and 72 is a main switching element such as a transistor, which together with the motor 42 form a closed main circuit. The battery 70 is mounted above the crank pedal 18 as shown in FIG. 2, and the main switching element 72 and controller 60 are housed in a control box 74 below the seat 16. This controller 60 can be of a chopper type, for example, which switches the main switching element 72 at high speed and controls the conduction rate of the motor current so that the target drive torque is achieved.

In the above embodiment, the motor driving force is added to reduce the manual driving force using the control characteristics shown in FIG. The human power driving force may be increased by generating . In this case, the load on human power increases, so it is suitable for increasing physical strength, and it can also provide a kind of engine braking effect when going downhill. A brake sensor may detect that the brake has been applied and cause the motor to generate braking force.

The present invention is applicable not only to bicycles, but also to and includes human-driven three- and four-wheeled vehicles, vehicles for the handicapped, rehabilitation equipment, play equipment, fitness equipment, robots, and the like.

[0022]

[Effects of the Invention] As described above, the present invention calculates the average value (Thm) of the drive torque (Th) of the human-powered drive system,
Since the drive torque (TM) by the electric motor is controlled using a predetermined conversion characteristic with respect to this average value (Thm), the human drive torque (Thm) is controlled as the crankshaft rotates.
Even if the motor drive torque (TM
) does not fluctuate periodically, and the fluctuations in the motor current become smaller. Therefore, the consumption of the battery for driving the motor is reduced, and the distance traveled can be increased while using the motor in combination. In addition, the assist force of the motor can be automatically controlled without operating the transmission or throttle lever at all, making it possible to ride smoothly while reducing human effort without compromising the feeling of cycling. Furthermore, if the braking force is generated by a motor, it becomes suitable for increasing physical strength.

[Brief explanation of drawings]

[Figure 1] Block diagram showing the concept of the present invention

[Figure 2] Diagram showing an example of application to bicycles

[Figure 3] Developed diagram of the drive system

[Figure 4] Diagram showing an example of the load detection means

[Fig. 5] A diagram showing another example of the load detection means.

[Figure 6] Conversion characteristic diagram of drive torque by human power and drive torque by motor

[Figure 7] Diagram showing periodic changes in drive torque due to human power

[Explanation of symbols]

10 Drive wheel 20 Human power drive system 30 Load detection means 40 Motor drive system 42 Motor 50 Crank angle detection means 60 Controller

Claims (1)

[Claims] Claim 1: A human-powered drive system with an electric motor in which a human-powered drive system using a crank pedal and a drive system using an electric motor using a battery are installed in parallel, a load for detecting the load of the human-powered drive system. a detection means, a crank angle detection means for detecting a rotation angle of a crankshaft rotationally driven by the crank pedal, and an average load detection means for calculating an average load of the human-powered drive system using the detected crank angle; A human power drive device with an electric motor, comprising: a controller that controls the output of the electric motor with predetermined conversion characteristics with respect to the detected average load.