# Patent

## Title
Hybrid electric vehicle

## Abstract

A hybrid electric vehicle includes a wheel, a wheel driving device coupled with the wheel and including an electric motor, a battery unit including a first battery and a second battery, a generator for recharging the first battery and the second battery, a fuel engine operable to drive the generator to generate electricity, a first switch for establishing electrical connection between the generator and each of the first battery and the second battery, a second switch for establishing electrical connection between the electric motor and each of the first battery and the second battery, and a control unit operable to control the first switch and the second switch to make or break electrical connection.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of Taiwanese application no. 103108737, filed on Mar. 12, 2014.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid electric vehicle.
2. Description of the Related Art
Referring to FIG. 1, a conventional electric vehicle has wheels 93 and an electric motor 91 that drives rotation of the wheels 93 through a transmission unit 92, and that receives electricity from a battery 94. By using the battery 94 as a power source for the electric motor 91, air pollution attributed to vehicles having conventional fuel (such as gasoline, diesel, etc.) engines may be prevented.
However, once the battery 94 is drained, the electric vehicle has to be moved to a specific location that has battery recharging equipment, creating inconvenience. Thus, a hybrid electric vehicle is proposed to resolve such inconvenience.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a hybrid electric vehicle having a generator to charge a battery unit.
Accordingly, the hybrid electric vehicle of this invention includes a wheel, a wheel driving device, a battery unit, a generator, a fuel engine, a first switch, a second switch, and a control unit. The wheel driving device is coupled with the wheel for driving rotation of the wheel, and the wheel driving device includes an electric motor. The battery unit provides electricity to the electric motor, and the battery unit includes a first battery and a second battery that are rechargeable. The generator recharges the first battery and the second battery. The fuel engine is coupled with the generator and is operable to drive the generator to generate electricity. The first switch establishes electrical connection between the generator and each of the first battery and the second battery. The second switch establishes electrical connection between the electric motor and each of the first battery and the second battery. The control unit is electrically coupled with the first switch and the second switch and is operable to control the first switch and the second switch to make or break electrical connection.



BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
FIG. 1 is a schematic block diagram illustrating a conventional electric vehicle;
FIG. 2 is a schematic block diagram illustrating a preferred embodiment of a hybrid electric vehicle in the present invention; and
FIG. 3 is a schematic diagram illustrating finite states related to operation of the hybrid electric vehicle in the preferred embodiment of the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 2, a hybrid electric vehicle 100 in a preferred embodiment of the present invention includes a plurality of wheels 1, a battery unit 2, an electric motor 3, a fuel engine 4, a generator 5, a first switch S1, a second switch S2, a control unit 6, a first detector M1, a second detector M2, and a transmission device 7. In this embodiment, the hybrid electric vehicle 100 has four wheels, but is not limited to having four.
The transmission device 7 is coupled between the electric motor 3 and each of the wheels 1, and cooperates with the electric motor 3 to form a wheel driving device. The electric motor 3 receives electricity from the battery unit 2, and the electric motor 3 drives, through the transmission device 7, the wheels 1 to rotate. The generator 5 is coupled with the fuel engine 4 and is driven by the fuel engine 4 to generate electricity for charging the battery unit 2.
The battery unit 2 includes a first battery B1 and a second battery B2 that are rechargeable. The first switch S1 has a first terminal electrically coupled with the first battery B1, a second terminal electrically coupled with the second battery B2, a third terminal electrically coupled with the generator 5, and a fourth terminal electrically coupled the control unit 6 for receiving a first control signal n1. The second switch S2 has a first terminal electrically coupled with the first battery B1, a second terminal electrically coupled with the second battery B2, a third terminal electrically coupled with the electric motor 3, and a fourth terminal electrically coupled with the control unit 6 for receiving a second control signal n2.
The control unit 6 controls the first switch S1 such that the first battery B1 and the second battery B2 are not connected to the generator 5 at the same time, and controls the second switch S2 such that the first battery B1 and the second battery B2 are not connected to the electric motor 3 at the same time.
Specifically, the control unit 6 is operable to control the first switch S1 to either electrically connect the third terminal of the first switch S1 with the first terminal of the first switch S1 and electrically disconnect the third terminal of the first switch S1 with the second terminal of the first switch S1 such that recharging of the first battery B1 by the generator 5 is enabled, or electrically connect the third terminal of the first switch S1 with the second terminal of the first switch S1 and electrically disconnect the third terminal of the first switch S1 form the first terminal of the first switch S1 such that recharging of the second battery B2 by the generator 5 is enabled.
The control unit 6 is further operable to control the second switch S2 to either electrically connect the third terminal of the second switch S2 with the first terminal of the second switch S2 and electrically disconnect the third terminal of the second switch S2 with the second terminal of the second switch S2 such that the first battery B1 is able to supply electricity to the electric motor 3, or electrically connect the third terminal of the second switch S2 with the second terminal of the second switch S2 and electrically disconnect the third terminal of the second switch S2 from the first terminal of the second switch S2 such that the second battery B2 is able to supply electricity to the electric motor 3.
The first detector M1 is electrically coupled with the control unit 6 and the first battery B1, and is operable to detect a battery level of the first battery B1 and to generate a first detector signal m1 that is based on the battery level of the first battery B1. The second detector M2 is electrically coupled with the control unit 6 and the second battery B2, and is operable to detect a battery level of the second battery B2 and to generate a second detector signal m2 that is based on the battery level of the second battery B2.
The control unit 6 is electrically coupled with the fuel engine 4, the fourth terminal of the first switch S1, the fourth terminal of the second switch S2, the first detector M1 and the second detector M2. The control unit 6 controls operations (activation/deactivation) of the fuel engine 4, and generates the first control signal n1 and the second control signal n2. In this embodiment, the control unit 6 controls the fuel engine 4, the first switch S1 and the second switch S2 based on the first detector signal m1 and the second detector signal m2.
Referring further to FIG. 3, the hybrid electric vehicle 100 operates in a first state S01 when the control unit 6 determines that the battery level of the first battery B1 is greater than a first predetermined battery level, and that the battery level of the second battery B2 is not greater than a second predetermined battery level. While the hybrid electric vehicle 100 operates in the first state S01, the control unit 6 is operable to activate the fuel engine 4, controls the first switch S1 to electrically connect the third terminal of the first switch S1 with the second terminal of the first switch S1 and electrically disconnect the third terminal of the first switch S1 from the first terminal of the first switch S1 such that the second battery B2 is recharged by the generator 5, and controls the second switch S2 to electrically connect the third terminal of the second switch S2 with the first terminal of the second switch S2 and electrically disconnect the third terminal of the second switch S2 from the second terminal of the second switch S2 such that the first battery B1 provides electricity to the electric motor 3.
The hybrid electric vehicle 100 transitions from operation in the first state S01 to operation in a second state S02 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the first state S01, that the battery level of the first battery B1 drops to the first predetermined battery level, and that the battery level of the second battery B2 rises to be greater than the second predetermined battery level.
While the hybrid electric vehicle 100 operates in the second state S02, the control unit 6 is operable to activate the fuel engine 4, controls the first switch S1 to electrically connect the third terminal of the first switch S1 with the first terminal of the first switch S1 and electrically disconnect the third terminal of the first switch S1 from the second terminal of the first switch S1 such that the first battery B1 is recharged by the generator 5, and controls the second switch S2 to electrically connect the third terminal of the second switch S2 from the second terminal of the second switch S2 and electrically disconnect the third terminal of the second switch S2 with the first terminal of the second switch S2 such that the second battery B2 provides electricity to the electric motor 3.
The hybrid electric vehicle 100 transitions from operation in the second state S02 to operation in the first state S01 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the second state S02, that the battery level of the second battery B2 drops to the second predetermined battery level, and that the battery level of the first battery B1 rises to be greater than the first predetermined level.
The hybrid electric vehicle 100 transitions from operation in the first state S01 to operation in a third state S03 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the first state S01, that the battery level of the first battery B1 is above the first predetermined battery level, and that the battery level of the second battery B2 rises to a third predetermined battery level that is higher than the second predetermined battery level. While the hybrid electric vehicle 100 operates in the third state S03, the control unit 6 is operable to control the second switch S2 such that the first battery B1 continues to provide electricity to the electric motor 3, and the control unit 6 is operable to deactivate the fuel engine 4, such that recharging of the second battery B2 is stopped, thus preventing overcharging of the second battery B2.
The hybrid electric vehicle 100 transitions from operation in the third state S03 to operation in the second state S02 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the third state S03, that the battery level of the first battery B1 drops to the first predetermined battery level.
The hybrid electric vehicle 100 transitions from operation in the second state S02 to operation in a fourth state S04 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the second state S02, that the battery level of the second battery B2 is above the second predetermined battery level, and that the battery level of the first battery B1 rises to a fourth predetermined battery level that is higher than the first predetermined battery level.
While the hybrid electric vehicle 100 operates in the fourth state S04, the control unit 6 is operable to control the second switch S2 such that the second battery B2 continues to provide electricity to the electric motor 3, and the control unit 6 is operable to deactivate the fuel engine 4, such that recharging of the first battery B1 is stopped, thus preventing overcharging of the second battery B1.
The hybrid electric vehicle 100 transitions from operation in the fourth state S04 to operation in the first state S01 when the control unit 6 determines, while the hybrid electric vehicle 100 operates in the fourth state S04, that the battery level of the second battery B2 drops to the second predetermined battery level.
In summary, the battery unit 2 in the hybrid electric vehicle 100 of the present invention is charged by the generator 5 that is coupled with the fuel engine 4, effectively prolonging the operating time of the hybrid electric vehicle 100. By this virtue, the hybrid electric vehicle 100 does not have to immediately travel to a specific location for charging when the battery is low. The control unit 6, according to the battery levels of the first battery B1 and the second battery B2, controls the fuel engine 4, the first switch S1 and the second switch S2 to switch operation of the hybrid electric vehicle 100 among the first state S01, the second state S02, the third state S03 and the fourth state S04. By such virtue, the electric motor 3 is continuously supplied with electricity from one of the first battery B1 and the second battery B2. This prevents simultaneous charging and discharging of the first battery B1 or the second battery B2, prolonging service life of the first battery B1 and the second battery B2.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.

## Claims

1. A hybrid electric vehicle comprising:
a wheel;
a wheel driving device coupled with the wheel for driving rotation of the wheel, the wheel driving device including an electric motor;
a battery unit for providing electricity to the electric motor, the battery unit including a first battery and a second battery that are rechargeable;
a generator for recharging the first battery and the second battery;
a fuel engine coupled with the generator and operable to drive the generator to generate electricity;
a first switch for establishing electrical connection between the generator and each of the first battery and the second battery;
a second switch for establishing electrical connection between the electric motor and each of the first battery and the second battery;
a control unit electrically coupled with the first switch and the second switch and operable to control the first switch and the second switch to make or break electrical connection,
a first detector electrically coupled with the control unit and the first battery, and operable to detect a battery level of the first battery and to generate a first detector signal that is based on the battery level of the first battery; and
a second detector electrically coupled with the control unit and the second battery, and operable to detect a battery level of the second battery and to generate a second detector signal that is based on the battery level of the second battery,
wherein:
the first switch has a first terminal electrically coupled with the first battery, a second terminal electrically coupled with the second battery, a third terminal electrically coupled with the generator, and a fourth terminal electrically coupled the control unit for receiving a first control signal,
the second switch has a first terminal electrically coupled with the first battery, a second terminal electrically coupled with the second batter, a third terminal electrically coupled with the electric motor, and a fourth terminal electrically coupled with the control unit for receiving a second control signal,
the control unit is further coupled electrically to the fuel engine, and controls operations of the fuel engine, the first switch and the second switch based on the first detector signal and the second detector signal,
the hybrid electric vehicle operates in a first state which the control unit determines that the battery level of the first battery is greater than a first predetermined battery level, and that the battery level of the second battery is not greater than a second predetermined battery level, and
while the hybrid electric vehicle operates in the first state, the control unit is operable to activate the fuel engine, controls the first switch to electrically connect the third terminal of the first switch with the second terminal of the first switch and electrically disconnect the third terminal of the first switch from the first terminal of the first switch such that the second battery is recharged by the generator, and controls the second switch to electrically connect the third terminal of the second switch with the first terminal of the second switch and electrically disconnect the third terminal of the second switch from second terminal of the second switch such that the first battery provides electricity to the electric motor.

2. The hybrid electric vehicle as claimed in claim 1, wherein the control unit controls the first switch such that the first battery and the second battery are not connected to the generator at the same time, and controls the second switch such that the first battery and the second battery are not connected to the electric motor at the same time.

3. The hybrid electric vehicle as claimed in claim 1, wherein:
the hybrid electric vehicle transitions from operation in the first state to operation in a second state when the control unit determines, while the hybrid electric vehicle operates in the first state, that the battery level of the first battery drops to the first predetermined battery level, and that the battery level of the second battery rises to be greater than the second predetermined battery level; and
while the hybrid electric vehicle operates in the second state, the control unit is operable to activate the fuel engine, controls the first switch to electrically connect the third terminal of the first switch with the first terminal of the first switch and electrically disconnect the third terminal of the first switch from the second terminal of the first switch such that the first battery is recharged by the generator, and controls the second switch to electrically connect the third terminal of the second switch with the second terminal of the second switch and electrically disconnect the third terminal of the second switch from the first terminal of the second switch such that the second battery provides electricity to the electric motor.

4. The hybrid electric vehicle as claimed in claim 3, wherein:
the hybrid electric vehicle transitions from operation in the second state to operation in the first state when the control unit determines, while the hybrid electric vehicle operates in the second state, that the battery level of the second battery drops to the second predetermined battery level, and that the battery level of the first battery rises to be greater than the first predetermined level.

5. The hybrid electric vehicle as claimed in claim 4, wherein:
the hybrid electric vehicle transitions from operation in the first state to operation in a third state when the control unit determines, while the hybrid electric vehicle operates in the first state, that the battery level of the first battery is above the first predetermined battery level, and that the battery level of the second battery rises to a third predetermined battery level that is higher than the second predetermined battery level; and while the hybrid electric vehicle operates in the third state, the control unit is operable to deactivate the fuel engine, such that recharging of the second battery is stopped.

6. The hybrid electric vehicle as claimed in claim 5, wherein:
while the hybrid electric vehicle operates in the third state, the control unit controls the second switch such that the first battery continues to provide electricity to the electric motor.

7. The hybrid electric vehicle as claimed in claim 6, wherein:
the hybrid electric vehicle transitions from operation in the third state to operation in the second state when the control unit determines, while the hybrid electric vehicle operates in the third state, that the battery level of the first battery drops to the first predetermined battery level.

8. The hybrid electric vehicle as claimed in claim 4, wherein:
the hybrid electric vehicle transitions from operation in the second state to operation in a fourth state when the control unit determines, while the hybrid electric vehicle operates in the second state, that the battery level of the second battery is above the second predetermined battery level, and that the battery level of the first battery rises to a fourth predetermined battery level that is higher than the first predetermined battery level; and while the hybrid electric vehicle operates in the fourth state, the control unit is operable to deactivate the fuel engine, such that recharging of the first battery is stopped.

9. The hybrid electric vehicle as claimed in claim 8, wherein:
while the hybrid electric vehicle operates in the fourth state, the control unit controls the second switch such that the second battery continues to provide electricity to the electric motor.

10. The hybrid electric vehicle as claimed in claim 9, wherein:
the hybrid electric vehicle transitions from operation in the fourth state to operation in the first state when the control unit determines, while the hybrid electric vehicle operates in the fourth state, that the battery level of the second battery drops to the second predetermined battery level.