JP2000079895A - Electric assist vehicle - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable human power to be detected using a low-cost, low-cost rotation detection sensor while miniaturizing. SOLUTION: A resultant shaft 3 connected to a rear wheel and a motor and a pedal crankshaft 2 are connected by an elastic body 4 so that human power and power of the motor are combined. First and second sun gears 16 and 18 and first and second planetary gears 17 and 19
And a planetary gear mechanism including a carrier 20 and first and second rotation detection sensors 13 and 14, and a human power detection unit 12 connected to the pedal crankshaft 12 and the resultant shaft 3.
The human power detecting means 12 is configured to detect a phase difference between the rotation of the first sun gear 16 and the rotation of the second sun gear 18 from the detection values of the two rotation detection sensors.

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 such as an electric assist bicycle or an electric assist wheelchair.

[0002]

2. Description of the Related Art Conventional electric assist bicycles detect human power (stepping force at the time of depressing a pedal) by means of human power detecting means.
It employs a structure that controls the power of the motor according to human power. As the human power detecting means, for example, JP-A-8-31
As disclosed in Japanese Patent No. 3375, the rotation of a pedal crankshaft is detected by a rotation detection sensor, and the rotation of an output shaft connected to the pedal crankshaft via an elastic body is detected by a rotation detection sensor. In some cases, human power is detected from a phase difference between axes.

Each of the two rotation detection sensors is formed by a proximity switch, and adopts a structure for detecting gear teeth provided on a pedal crankshaft and gear teeth provided on an output shaft.

[0004]

However, when the rotation detecting sensor is used to detect human power as described above, there is a problem that the manufacturing cost is increased. This is because, for example, in a vehicle such as a battery-assisted bicycle, in which the space in which components can be mounted is narrow, the gears detected by the rotation detection sensor must be formed to have a small diameter. This is because a rotation detection sensor that can be used must have high resolution even if it is expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an electric assist bicycle capable of detecting human power by using a low-priced rotation detection sensor with a low resolution while reducing the size of a vehicle body. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION An electric assist vehicle according to the present invention is an electric assist vehicle that controls the power of a motor in accordance with the human power detected by a human power detecting means and travels a vehicle body using the human power and the power of the motor. An input member rotating by human power and an output member connected to the drive wheel are arranged on the same axis and connected to each other via an elastic body, and the human power detecting means rotates integrally with the input member. The first main gear and the first main gear are formed so as to have different numbers of teeth, and a second main gear that rotates integrally with the output member and a first main gear that meshes with the first main gear. A planetary gear and the second
A second planetary gear that meshes with the main gear and rotates integrally with the first planetary gear; and revolves the first and second planetary gears around the axes of the first and second main gears. A freely rotating carrier, a first rotation detecting sensor for detecting rotation of the first main gear, and a second rotation detecting sensor for detecting rotation of the carrier; The phase difference between the rotation of the first main gear and the rotation of the second main gear is detected from the detection value of the rotation detection sensor.

According to the present invention, the carrier rotates at an increased speed with respect to the first main gear in accordance with the difference between the rotation speed of the first main gear and the rotation speed of the second main gear. , The rotation speed difference between the rotation speed of the first main gear and the rotation speed of the carrier is
Is larger than the rotation speed difference between the rotation speed of the main gear and the rotation speed of the second main gear. Therefore, as the two rotation detection sensors, those capable of detecting a relatively large difference in the number of rotations, that is, those having lower resolution than the conventional one can be used. In addition, since the carrier rotates at an increased speed with respect to the first main gear, even if the phase difference between the input member and the output member of the manual drive system is small, the teeth passing near the rotation detection sensor can be used. , The detection accuracy can be increased. Also, the gear group that constitutes the human power detection means is outside the power transmission system that transmits the human power to the drive wheels, and does not transmit a large force for running the vehicle body, so it is made of a lightweight and inexpensive material. It can be formed small.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment An embodiment of an electric assist vehicle according to the present invention will be described with reference to FIG.
This will be described in detail. FIG. 1 is a simplified configuration diagram showing a power unit of an electric assist vehicle according to the present invention. In FIG. 1, reference numeral 1 denotes a power unit for an electric assist vehicle according to this embodiment. The power unit 1 is mounted on a hanger portion of an electric bicycle and drives a rear wheel as a driving wheel. The power unit 1 has a pedal crankshaft 2 penetrated through a cylindrical resultant shaft 3, and these two shafts are compressed coil springs or the like. In addition to being connected to each other via an elastic body 4 such as a torsion spring, a motor 6 is connected to the resultant shaft 3 via a one-way clutch 5 and a speed reducer (not shown). In this embodiment, the pedal crankshaft 2 constitutes an input member according to the present invention, and the resultant shaft 3 constitutes an output member.

The one-way clutch 5 has a structure in which power is transmitted only in a direction from the motor 6 toward the resultant shaft 3. A one-way clutch 7 is also provided between the pedal crankshaft 2 and the elastic body 4 so that the power is transmitted from the pedal crankshaft 2 to the resultant shaft 3.

A motor drive system extending from the motor 6 to the resultant shaft 3 via the one-way clutch 5 includes a rotation direction of the pedal crankshaft 2 when the pedal crankshaft 2 is rotated so that the vehicle body moves forward. The rotation direction of the resultant shaft 3 is configured to match.

In this embodiment, the pedal crankshaft 2 and the resultant force shaft 3 are connected to each other via an elastic body 4 so that the human power and the power of the motor 6 are combined by the resultant force shaft 3. ing. Also, this power unit 1
A chain sprocket 8 is fixed to the end of the resultant shaft 3 on the outer side of the vehicle body, and a chain 9 for transmitting power from the power unit 1 to a rear wheel (not shown) as a driving wheel is mounted on the chain sprocket 8. Wrapped around. Note that a belt can be used instead of the chain 9.

The pedal crankshaft 2 is rotatably supported by a power unit housing H via bearings, and has cranks 11 having pedals 10 at both ends. The resultant shaft 3 through which the pedal crankshaft 2 passes is also rotatably supported by the housing H via a bearing together with the pedal crankshaft 2. In FIG. 1, a bearing B that supports the pedal crankshaft 2 and the resultant shaft 3 is indicated by reference numeral B.

The human-powered driving system of this electric assist bicycle is constituted by various members between the pedal 10 and a rear wheel (not shown). That is, when the motor 6 is not rotating, the pedal 10, the crank 11, the pedal crankshaft 2, the elastic body 4, the resultant shaft 3, the chain sprocket 8, the chain 9, and the hub of the rear wheel to which the rotation is transmitted by the chain 9 A human-powered drive system is constituted by the above.
On the other hand, when the motor 6 rotates, the power of the motor 6 is applied to the resultant shaft 3, and the human power (the pressing force when the pedal 10 is depressed) and the power of the motor 6 are combined by the resultant shaft 3. Therefore, during rotation of the motor, the power unit 1 drives the rear wheels with the resultant force of human power and the power of the motor 6.

The power of the motor 6 is controlled according to human power. In this embodiment, the magnitude of human power is detected by human power detection means 12 described later, and a current corresponding to the magnitude of human power is supplied to the motor 6.

The human power detecting means 12 includes a planetary gear mechanism described later, first and second rotation detecting sensors 13 and 14,
And the controller 15. The planetary gear mechanism includes a first sun gear 16 that rotates integrally with the pedal crankshaft 2 as an input member of a manual drive system,
A first planetary gear 17 meshing with the sun gear 16 of the first embodiment, a second sun gear 18 rotating integrally with the resultant force shaft 3, and a first planetary gear 17 meshing with the second sun gear 18 And a second planetary gear 19 which is connected to the first planetary gear 17 via a collar 17a and rotates integrally with the first planetary gear 17, and the first and second planetary gears 17 and 19 are connected to the axis (the And a carrier 20 that revolves around the first and second sun gears 16 and 18).

The first sun gear 16 and the second sun gear 18 constitute first and second main gears according to the present invention. The sun gears 16 and 18 are formed so that the number of teeth is different from each other. For this reason, the first planetary gear 17 and the second planetary gear 1
Nine also have different numbers of teeth.

In the power unit 1, the first
Of the sun gear 16 of the first rotation detection sensor 13
And the teeth 20a provided on the carrier 20 are
Is detected by the rotation detection sensor 14. The first and second rotation detection sensors 13 and 14 are formed by proximity switches having an electromagnetic pickup, and have a structure for sending a detection signal to the controller 15. Also,
These rotation detection sensors 13 and 14 are fixed to the power unit housing H. The teeth 20a are provided on a carrier 2 arranged coaxially with the pedal crankshaft 2 and the resultant shaft 3.
A large number are formed along the circumferential direction on the 0 disk portion. In addition,
In this embodiment, an example is shown in which the teeth 20a and the second rotation detection sensor 14 are disposed on the opposite side of the first rotation detection sensor 13 across the planetary gear mechanism.
Also, the second rotation detection sensor 14 can be disposed on the same side as the first rotation detection sensor 13.

The controller 15 includes the first and second
The rotation speed difference between the first sun gear 16 and the carrier 20 is determined based on the detection values of the rotation detection sensors 13 and 14, and the rotation speed difference (the phase difference between the pedal crankshaft 2 and the resultant shaft 3) is determined. A configuration for supplying a current to the motor 6 is employed.

In the power unit 1 configured as described above, when the pedal 10 is depressed, the pedal crankshaft 2 rotates, and this rotation is transmitted to the resultant shaft 3 via the elastic body 4. When the motor 6 is stopped, only the force for depressing the pedal 10, that is, the human power is transmitted from the resultant shaft 3 to the rear wheels via the chain sprocket 8 and the chain 9. When the motor 6 rotates, the rotation of the motor 6 is transmitted to the resultant shaft 3 via the one-way clutch 5, and the human power transmitted from the pedal crankshaft 2 and the power of the motor 6 are synthesized by the resultant shaft 3. Is transmitted to the rear wheels.

When the pedal crankshaft 2 and the resultant shaft 3 rotate at, for example, the same rotation speed (in phase), the rotation speed of the first sun gear 16 and the rotation speed of the second sun gear 18 become equal. These two sun gears 16 and 18 have different numbers of teeth, and the first and second planetary gears 17 and 19 meshing with them have different numbers of teeth. The second planetary gear 19 attempts to rotate at a rotational speed corresponding to the difference in the number of teeth. However, the planetary gears 17 and 19, which are connected to each other and rotate differently, are suppressed from rotating, and as a result are united. The planetary gears 17 and 19 revolve around the sun gears 16 and 18 without rotating in the same direction as the sun gears 16 and 18. That is, the carrier 20 rotates. The rotation speed of the carrier 20 is controlled by the first and second sun gears 16 and 18.
Is the same as the number of rotations.

Even when traveling on an uphill, accelerating, or traveling at a constant speed, the depressing force of the pedal 10 becomes substantially zero at the upper and lower dead centers and pulsates so as to become the maximum at 90 ° from the upper dead center. Change. Therefore, as the pedaling force gradually increases toward 90 ° from the top dead center, the phase of the pedal crankshaft 2 gradually advances from the resultant shaft 3 against the elastic force of the elastic body 4, and the The phase of one sun gear 16 gradually advances from that of the second sun gear 18. At this time, the sun gear 16 has a larger number of teeth than the sun gear 18, the planetary gear 19 has a larger number of teeth than the planetary gear 17, and the difference in the number of teeth is smaller, while keeping the same inter-axis distance. As a result, the planetary gears 17 and 19 are integrally rotated to rotate, and as a result, the carrier 20 is rotated at a higher speed than the first sun gear 16 and rotates in the direction opposite to the rotation direction of the pedal crankshaft 2. The rotation of the carrier 20 increases with a higher rotation rate change rate than the rotation rate change rate of the sun gear 16. For this reason, the rotation speed difference between the rotation speed of the first sun gear 16 and the rotation speed of the carrier 20 gradually increases as the phase of the pedal crankshaft 2 advances with respect to the resultant shaft 3.

The rotation of the first sun gear 16 and the carrier 20
Are detected by the rotation detection sensors 13 and 14, and the controller 15 supplies a current to the motor 6 in accordance with the rotation speed difference. As a result, the power of the motor 6 increases by an amount corresponding to the increase in human power. When the phase shift becomes maximum at the position of 90 °, the planetary gears 17 and 19 no longer rotate, and the carrier 20 rotates at the same rotational speed as the pedal crankshaft 2 and the resultant shaft 3, and the rotational speed difference. Becomes zero, but the controller 15 stores the immediately preceding rotational speed difference, and continues to supply the motor 6 with an appropriate current. Subsequently, when the pedaling force decreases toward the bottom dead center, the phase shift attempts to return to the original state due to the action of the elastic body 4, so that the carrier 20 moves in the same direction as the pedal crankshaft 2 in the opposite action as described above. 1 sun gear 16
The rotation speed is further increased, and the rotation speed difference gradually decreases as the phase of the pedal crankshaft 2 returns to the original state. In addition,
When the rotation speed of the pedal crankshaft 2 is lower than the resultant shaft 3, the power unit 1 is configured to cut off the current supplied to the motor 6.

Here, the first and second sun gears 16,
The relationship between the rotation of 18 and the rotation of the carrier 20 will be described. The rotation speed α of the first sun gear 16 for the carrier 20 to make one rotation while the second sun gear 18 is stopped.
(Hereinafter, this rotation speed is referred to as a differential rotation speed) can be obtained by the following equation (1).

Α = {1− (Tb / Ta × Tc / Ta)} (1) In the equation (1), Ta indicates the number of teeth of the first sun gear 16, and Tb indicates the number of teeth of the first sun gear 16. 2 shows the number of teeth of the sun gear 18 and T
c indicates the number of teeth of the first planetary gear 17, and Td indicates the number of teeth of the second planetary gear 19. That is, the first sun gear 1 is shifted from the second sun gear 18 by the α rotation shown in the above equation (1).
By increasing the rotation of 6, the carrier 20 makes one rotation.

For example, when Ta is set to 40 and Tb is set to 38
When Tc is set to 30 and Td is set to 32, the differential rotation speed α = {1− (38/32 × 30/40)} =
0.109375 ‥‥. For this reason, when each gear is formed with the number of teeth described above, the first sun gear 16 rotates by 0.109375 ° relative to the second sun gear 18 by differential rotation, so that the carrier 20 rotates one rotation. I do.

As a result, the ratio of the rotation speed of the carrier 20 to the differential rotation speed α (one rotation of the carrier / differential rotation speed α)
Becomes 1 / 0.109375 ≒ 9.143. That is, the rotation speed of the carrier 20 is about nine times the differential rotation speed α, and the rotation speed difference between the first sun gear 16 and the carrier 20 is larger than the rotation speed difference between the second sun gear 18.

Therefore, the rotation detecting sensors 13 and 14
, It is sufficient to detect a relatively large difference in the number of rotations, so that a resolution lower than that of the related art can be used. Moreover, since the carrier 20 rotates at an increased speed with respect to the first sun gear 16, even if the phase difference between the pedal crankshaft 2 and the resultant shaft 3 is small, the carrier 20 passes near the rotation detection sensor 14. Since the number of teeth to be increased increases, the detection accuracy can be increased.

The gear group forming the human power detecting means 12 is outside the power transmission system for transmitting the human power to the rear wheels, and does not transmit a large force for running the vehicle body. It can be made of a lightweight and inexpensive material, and can be made compact.

The first sun gear 16 and the second sun gear 18 can be replaced with internal gears (outer peripheral gears) in which the first and second planetary gears 17, 19 mesh radially inward. . Further, in this embodiment, the power unit mounted on the hanger portion of the battery-assisted bicycle has been described, but this power unit may be provided on the hub of the rear wheel of the battery-assisted bicycle. When this configuration is adopted, the rotation shaft on the rear wheel side of the manual drive system is used as the input shaft, the resultant shaft connecting the motor in the hub, and the input shaft are arranged on the same axis, and these are elastic bodies. Connected to each other via. Then, a planetary gear mechanism is connected to the input shaft and the resultant shaft.

Second Embodiment The electrically assisted vehicle according to the present invention can be configured with a human drive system and a motor drive system separately as shown in FIG.

FIG. 2 is a block diagram showing an embodiment of a power unit for an electrically assisted vehicle. In the figure, the same or equivalent members as those described in FIG. 1 are denoted by the same reference numerals, and detailed description is omitted.

The power unit 1 for an electrically assisted bicycle shown in FIG. 2 has a human-powered rear wheel drive system 22 for transmitting the rotation of the pedal crankshaft 2 to the rear wheel 21 and a motor front wheel drive system for driving the front wheel 23 by the motor 6. 24.

The manual rear wheel drive system 22 has a structure in which the motor drive system is omitted from the power unit 1 used in the first embodiment. That is, the rear wheel drive system 22 is configured by connecting the output member 3 to the pedal crankshaft 2 via the one-way clutch 7 and the elastic body 4.

The motor front wheel drive system 24 has a structure in which the motor 6 is built in a hub (not shown) of the front wheel 23 and rotates the hub with respect to the axle. The output of this motor 6 is
Similar to the first embodiment, the human power detecting means 1
The controller 15 controls in accordance with the magnitude of the pedaling force detected by the second rotation detection sensors 13 and 14.

Thus, even if the rear-wheel drive system 22 and the front-wheel drive system 24 are separately provided, the same effect as that of the first embodiment can be obtained.

Further, in the above-described embodiment, an example has been described in which the present invention is applied to the power unit for an electric assist bicycle, but the present invention can be applied to other electric assist vehicles such as an electric wheelchair.

[0037]

As described above, according to the present invention, the carrier moves with respect to the first main gear in accordance with the rotation speed difference between the rotation speed of the first main gear and the rotation speed of the second main gear. Since the rotation speed is increased, the rotation speed difference between the rotation speed of the first main gear and the rotation speed of the carrier is equal to the rotation speed difference between the rotation speed of the first main gear and the rotation speed of the second main gear. Be larger. Moreover, since the carrier rotates at an increased speed with respect to the first main gear, even if the phase difference between the input member and the output member is small,
Since the number of teeth passing near the rotation detection sensor increases, detection accuracy can be increased. Therefore, as the two rotation detection sensors, those capable of detecting a relatively large difference in the number of rotations, that is, those having lower resolution and lower cost than in the past can be used. Further, the gear group that constitutes the human power detection means is outside the power transmission system that transmits the human power to the drive wheels, and does not transmit a large force for traveling the vehicle body. It can be formed small.

Therefore, the power of the motor can be accurately controlled, and an inexpensive and compact electric auxiliary vehicle can be provided.

[Brief description of the drawings]

FIG. 1 is a simplified configuration diagram showing a power unit of an electric assist vehicle according to the present invention.

FIG. 2 is a configuration diagram illustrating an embodiment of a power unit for an electrically assisted vehicle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power unit, 2 ... Pedal crankshaft, 3 ... Combined shaft, 4 ... Elastic body, 6 ... Motor, 12 ... Human power detection means, 1
3 ... first rotation detection sensor, 14 ... second rotation detection sensor, 15 ... controller, 16 ... first sun gear, 17
... first planetary gear, 18 ... second sun gear, 19 ... second
Planetary gears, 20 ... carrier.

Claims (1)

[Claims] An electric assist vehicle that controls the power of a motor in accordance with the human power detected by a human power detecting means and travels a vehicle body using the human power and the power of the motor. Arranged on the same axis and connected to each other via an elastic body,
A first main gear rotating integrally with the input member and a second main gear rotating integrally with the output member, the first main gear having a different number of teeth; A gear, a first planetary gear meshing with the first main gear, a second planetary gear meshing with the second main gear and rotating integrally with the first planetary gear; A carrier for supporting the first and second planetary gears around the axes of the first and second main gears, a first rotation detection sensor for detecting rotation of the first main gear, and the carrier A second rotation detection sensor for detecting the rotation of the first and second rotation detection sensors, and detects a phase difference between the rotation of the first main gear and the rotation of the second main gear from the detection values of the first and second rotation detection sensors. An electrically assisted vehicle characterized by having a configuration for detecting.