# US 2019/0315433 A1 · Electric assist system and electric assist vehicle

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- Number: US 2019/0315433 A1
- Document ID: US20190315433A1
- Status: Published application
- Kind: A1
- Application number: 16/454,638
- Filed: 2019-06-27
- Published: 2019-10-17
- Earliest claimed: 2016-12-28
- Assignees: Yamaha Hatsudoki Kabushiki Kaisha
- Applicants: Yamaha Hatsudoki Kabushiki Kaisha
- Inventors: Mitsuharu HASUMI
- Web page: https://patentgrep.com/patent/US20190315433A1

## CPC

- B60L 15/10: for automatic control superimposed on human control to limit the acceleration of the vehicle, e.g. to prevent excessive motor current (electric devices for safety purposes B60L3/00)
- B60L 50/20: using propulsion power generated by humans or animals
- B60W 30/188: Controlling power parameters of the driveline, e.g. determining the required power
- B60W 40/076: Slope angle of the road
- B62M 6/50: characterised by detectors or sensors, or arrangement thereof
- G01P 3/487: delivered by rotating magnets
- B60L 9/18: fed from DC supply lines
- B60L 15/2018: {for braking on a slope}
- B60L 15/2081: {for drive off on a slope}
- B60L 2200/12: Bikes
- B60L 2240/12: Speed
- B60L 2240/14: Acceleration
- B60L 2240/16: longitudinal
- B60L 2240/18: lateral
- B60L 2240/20: angular
- B60L 2240/642: Slope of road
- B60L 2260/44: by parameter estimation
- B62J 43/13: on rider-propelled cycles with additional electric propulsion
- B62M 6/45: Control or actuating devices therefor
- B62M 6/80: Accessories, e.g. power sources; Arrangements thereof
- Y02T 10/64: Electric machine technologies in electromobility
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/72: Electric energy management in electromobility
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B62M: RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR {SINGLE-TRACK} CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES (arrangements or mounting of transmissions in vehicles in general B60K; transmission elements per se F16)
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- B62J: CYCLE SADDLES OR SEATS; AUXILIARY DEVICES OR ACCESSORIES SPECIALLY ADAPTED TO CYCLES AND NOT OTHERWISE PROVIDED FOR, e.g. ARTICLE CARRIERS OR CYCLE PROTECTORS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An electric power assist system generates an appropriate level of assist power while an electric assist vehicle is running on a slope and includes an electric motor that generates an assist power to assist human power of a rider of the electric assist vehicle, a controller that controls a magnitude of the assist power to be generated by the electric motor, and an acceleration sensor that outputs an acceleration signal representing an acceleration in a travel direction of the electric assist vehicle. The controller acquires speed information representing a running speed of the electric assist vehicle based on an external signal, detects an inclination angle of a road surface based on the speed information and the acceleration signal, and causes the electric motor to generate an assist power of a magnitude in accordance with the inclination angle.

## Claims

### Claim 1

An electric power assist system for an electric assist vehicle, the electric power assist system comprising:
an electric motor that generates an assist power to assist human power of a rider of the electric assist vehicle;
a controller configured or programmed to control a magnitude of the assist power to be generated by the electric motor; and
an acceleration sensor that outputs an acceleration signal representing an acceleration Gx in a travel direction of the electric assist vehicle; wherein
the controller is configured or programmed to acquire speed information representing a running speed of the electric assist vehicle based on an external signal; and
the controller is configured or programmed to determine an inclination angle of a road surface based on the speed information and the acceleration signal, and to cause the electric motor to generate an assist power of a magnitude in accordance with the inclination angle.

### Claim 2 (depends on 1)

The electric power assist system of claim 1, further comprising:
a speed sensor that outputs a signal in accordance with a moving speed of the electric assist vehicle; wherein
the controller is configured or programmed to acquire the speed information based on the signal received from the speed sensor in accordance with the moving speed; and
the controller is configured or programmed to determine the inclination angle of the road surface based on the speed information and the acceleration signal.

### Claim 3 (depends on 1)

The electric power assist system of claim 1, wherein
the electric motor includes a rotor and a position detection sensor that detects a position of the rotor while the rotor is rotating; and
the controller is configured or programmed to determine a rotation speed of the rotor based on an output of the position detection sensor, and to multiply the rotation speed by a constant to acquire the speed information.

### Claim 4 (depends on 1)

The electric power assist system of claim 1, wherein
the electric assist vehicle includes a transmission including a plurality of transmission gear ranges and that outputs data representing a transmission gear range currently selected;
the electric motor includes a rotor and a position detection sensor that detects a position of the rotor while the rotor is rotating; and
the controller is configured or programmed to:
acquire data representing the transmission gear range;
determine a rotation speed of the rotor based on an output of the position detection sensor; and
acquire the speed information based on the rotation speed and the data representing the transmission gear range.

### Claim 5 (depends on 2)

The electric power assist system of claim 2, wherein the controller is configured or programmed to:
calculate a time-differential value of a speed in the travel direction;
subtract the time-differential value from the acceleration in the travel direction; and
divide the subtraction result by a gravitational acceleration to determine the inclination angle of the road surface, and
wherein the controller is configured or programmed to perform an inverse sine transformation on a division result obtained by dividing the subtraction result by the gravitational acceleration to determine the inclination angle of the road surface.

### Claim 6 (depends on 2)

The electric power assist system of claim 2, wherein the controller is configured or programmed to:
calculate a time-differential value of a speed in the travel direction;
subtract the time-differential value from the acceleration in the travel direction; and
divide the subtraction result by a gravitational acceleration to determine the inclination angle of the road surface, and
wherein
the controller includes a table that correlates each of a plurality of angles and a calculated value of a sine function for each of the angles; and
the controller is configured or programmed to divide the subtraction result by the gravitational acceleration, to refer to the table to acquire an angle corresponding to the division result, and to determine the angle as the inclination angle of the road surface.

### Claim 7 (depends on 1)

An electric assist vehicle comprising:
the electric power assist system according to claim 1; and
a speed sensor that outputs a signal in accordance with a moving speed of the electric assist vehicle.

### Claim 8

An electric power assist system for an electric assist vehicle, the electric power assist system comprising:
an electric motor that generates an assist power to assist human power of a rider of the electric assist vehicle;
a controller configured or programmed to control a magnitude of the assist power to be generated by the electric motor; and
an acceleration sensor that outputs an acceleration signal representing at least one of an acceleration in a first direction as a travel direction of the electric assist vehicle and an acceleration in a second direction perpendicular to both of the first direction and a road surface; wherein
the controller is configured or programmed to use the acceleration signal to determine that the electric assist vehicle is in a stop state, to determine an inclination angle of the road surface based on the acceleration signal that is output in the stop state, and to cause the electric motor to generate an assist power of a magnitude in accordance with the inclination angle when the rider starts pedaling the electric assist vehicle.

### Claim 9 (depends on 8)

The electric power assist system of claim 8, wherein the controller further includes a stop detection circuit that determines that the electric assist vehicle is in the stop state based on the acceleration signal that is output from the acceleration sensor.

### Claim 10 (depends on 9)

The electric power assist system of claim 9, wherein in a case in which the acceleration signal representing at least one of the acceleration in the first direction and the acceleration in the second direction fulfills a predefined stop determination condition, the stop detection circuit determines that the electric assist vehicle is at a stop.

### Claim 11 (depends on 10)

The electric power assist system of claim 10, wherein the stop determination condition includes a condition regarding a range of a signal level of the acceleration signal and a condition regarding a time period in which the acceleration signal is in the range of the signal level.

### Claim 12 (depends on 11)

The electric power assist system of claim 11, wherein
the acceleration sensor is a two-axis acceleration sensor or a three-axis acceleration sensor that outputs a first acceleration signal representing the acceleration in the first direction and a second acceleration signal representing the acceleration in the second direction; and
the stop detection circuit stores the stop determination condition for each of the first acceleration signal and the second acceleration signal.

### Claim 13

An electric power assist system for an electric assist vehicle, the electric power assist system comprising:
an electric motor that generates an assist power to assist human power of a rider of the electric assist vehicle;
a controller configured or programmed to generate a signal that controls an electric current in the electric motor to control a magnitude of the assist power to be generated by the electric motor; and
an acceleration sensor that outputs an acceleration signal representing at least one of an acceleration in a first direction as a travel direction of the electric assist vehicle and an acceleration in a second direction perpendicular to both of the first direction and a road surface;
the controller is configured or programmed to receive a detection signal based on whether the electric assist vehicle is at a stop or is running, the detection signal being received from at least one sensor that outputs the detection signal; and
the controller is configured or programmed to determine, based on the detection signal, that the electric assist vehicle is in a stop state, to determine an inclination angle of the road surface based on the acceleration signal that is output in the stop state, and to cause the electric motor to generate an assist power of a magnitude in accordance with the inclination angle when the rider starts pedaling the electric assist vehicle.

### Claim 14 (depends on 13)

The electric power assist system of claim 13, wherein the controller further includes a stop detection circuit that determines that the electric assist vehicle is in the stop state based on the detection signal that is output from the at least one sensor.

### Claim 15 (depends on 14)

The electric power assist system of claim 14, wherein
the at least one sensor is one or a plurality of sensors among a speed sensor, a torque sensor, a crank rotation sensor, and a Hall sensor that detects a rotation of the electric motor; and
in a case in which the detection signal fulfills a predefined stop determination condition, the stop detection circuit determines that the electric assist vehicle is at a stop.

### Claim 16 (depends on 8)

The electric power assist system of claim 8, wherein the controller is configured or programmed to include:
a gradient calculation circuit that calculates the inclination angle based on the acceleration signal that is output in the stop state;
an assist power calculation circuit that determines the magnitude of the assist power in accordance with the inclination angle; and
a motor driving circuit that causes the electric motor to generate the assist power determined by the assist power calculation circuit when the rider starts pedaling the electric assist vehicle; and
the gradient calculation circuit performs a calculation of arcsin(Gx/G) or arccos(Gz/G), in which G is a gravitational acceleration, to determine the inclination angle.

### Claim 17 (depends on 8)

The electric power assist system of claim 8, wherein the acceleration sensor is a two-axis acceleration sensor or a three-axis acceleration sensor that outputs a first acceleration signal representing the acceleration in the first direction and a second acceleration signal representing the acceleration in the second direction.

### Claim 18 (depends on 17)

The electric power assist system of claim 17, wherein the controller is configured or programmed to include:
a gradient calculation circuit that calculates the inclination angle based on the acceleration signal that is output in the stop state;
an assist power calculation circuit that determines the magnitude of the assist power in accordance with the inclination angle; and
a motor driving circuit that causes the electric motor to generate the assist power determined by the assist power calculation circuit when the rider starts pedaling the electric assist vehicle; and
the gradient calculation circuit performs at least one of calculations of arcsin(Gx/G), arccos(Gz/G), and arctan(Gx/Gz), in which G is a gravitational acceleration, to determine the inclination angle.

### Claim 19 (depends on 18)

The electric power assist system of claim 18, wherein the assist power calculation circuit stores in advance a rule defining a correlation between a magnitude of the inclination angle and the magnitude of the assist power, and uses the inclination angle calculated by the gradient calculation circuit and the rule to determine the magnitude of the assist power.

### Claim 20 (depends on 19)

The electric power assist system of claim 19, further comprising:
a switch selectable by the rider to select one of a plurality of driving modes that are different in the magnitude of the assist power while the electric assist vehicle is running; and
the assist power calculation circuit stores in advance the rule for each of the plurality of driving modes, and uses the inclination angle calculated by the gradient calculation circuit and the rule corresponding to the driving mode selected by the switch to determine the magnitude of the assist power when the rider starts pedaling the electric assist vehicle.

### Claim 21 (depends on 17)

The electric power assist system of claim 17, wherein the gradient calculation circuit uses the first acceleration signal and the second acceleration signal output by a low-pass filter to calculate the inclination angle.

### Claim 22 (depends on 8)

The electric power assist system of claim 8, wherein the controller is configured or programmed to cause the electric motor to generate the assist power in accordance with the inclination angle, with a start of pedaling being a time point at which the rider pedals the electric assist vehicle at most 5 times.

### Claim 23 (depends on 8)

An electric assist vehicle comprising the electric power assist system of claim 8.

### Claim 24 (depends on 13)

An electric assist vehicle comprising:
the electric power assist system according to claim 13; and
the at least one sensor.