Hybrid vehicle

Abstract

To provide a technique for assisting travel while maintaining a charging rate of a battery.SOLUTION: The hybrid vehicle includes: a battery; a first motor that drives wheels by using electric power supplied from the battery; an engine; a second motor that charges the battery with electric power generated by using power of the engine; a display device; and a control device that calculates a maximum cruising vehicle speed at which the vehicle can travel while maintaining a charging rate of the battery, based on a maximum output of the engine and a travel resistance of the vehicle, in a travel mode in which electric power is generated by the second motor while the wheels are driven by the first motor, and that displays the maximum cruising vehicle speed on the display device.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to hybrid vehicles.

Background Art

[0002] Patent Document 1 discloses a hybrid vehicle including a drive motor that drives wheels using electric power supplied from a battery, and a charging motor that charges the battery with electric power generated using the power of an engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As one of the driving modes of such a hybrid vehicle, a driving mode in which the drive motor drives the wheels while the charging motor generates electricity is known. In this driving mode, depending on the vehicle speed, the power consumption of the drive motor may be greater than the power generation of the charging motor, and the charge rate of the battery may decrease. If the decrease in the charge rate of the battery continues, the power of the battery will be exhausted, and ultimately the vehicle will not be able to run. In order to avoid such a situation, a technology for assisting driving is required.

Means for Solving the Problems

[0005] The hybrid vehicle disclosed in this specification includes a battery, a first motor that drives wheels using electric power supplied from the battery, an engine, a second motor that charges the battery with electric power generated using the power of the engine, a display device, and a control device that calculates the maximum cruising speed at which the vehicle can travel while maintaining the charge rate of the battery based on the maximum output of the engine and the running resistance of the vehicle in a running mode where the second motor generates electricity while the first motor drives the wheels, and causes the display device to display the maximum cruising speed.

[0006] In the above-described hybrid vehicle, the maximum cruising speed is displayed on the display device. Therefore, the driver can drive the vehicle while maintaining the charge rate of the battery by driving at a speed lower than the maximum cruising speed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0008] Hereinafter, with reference to the drawings, an embodiment of the hybrid vehicle 10 will be described. The hybrid vehicle 10 belongs to electric vehicles and is typically an electric vehicle (so-called automobile) that travels on a road surface. However, part or all of the technology described in this embodiment can be similarly applied to, for example, electric vehicles that travel on a track.

[0009] As shown in FIG. 1, the hybrid vehicle 10 includes a vehicle body 12 and a pair of wheels 14 provided on the vehicle body 12. The wheels 14 may be a pair of front wheels provided at the front of the vehicle body 12, or may be a pair of rear wheels provided at the rear of the vehicle body 12. Note that the specific configuration of the vehicle body 12 and the number of wheels included in the hybrid vehicle 10 are not particularly limited.

[0010] The hybrid vehicle 10 further includes a first motor (hereinafter referred to as “driving motor”) 22, a first power transmission path 24, and a differential gear 26. The driving motor 22 is connected to the pair of wheels 14 via the first power transmission path 24 and functions as a prime mover for driving the pair of wheels 14. The differential gear 26 provided in the first power transmission path 24 distributes the rotational motion (i.e., torque) output by the driving motor 22 to the pair of wheels 14. Further, the driving motor 22 can function not only as a prime mover but also as a generator for performing regenerative braking of the wheels 14. That is, when deceleration is required, the hybrid vehicle 10 can perform regenerative braking of the wheels 14 by causing the driving motor 22 to function as a generator. Although not shown, a speed reducer or a clutch may be provided in the first power transmission path 24 as necessary.

[0011] The hybrid vehicle 10 further includes an engine 32, a second motor (hereinafter referred to as “charging motor”) 34, and a second power transmission path 36. The engine 32 is connected to the charging motor 34 via the second power transmission path 36. The engine 32 is an internal combustion engine that burns fuel to generate power, and is not particularly limited, and examples thereof include a gasoline engine, a diesel engine, and a hydrogen engine. The charging motor 34 functions as a generator. That is, the hybrid vehicle 10 can generate electricity by the charging motor 34 by driving the charging motor 34 with the engine 32.

[0012] Hybrid vehicle 10 further includes a battery 40, a first power control unit (hereinafter referred to as "first PCU") 42, and a second power control unit (hereinafter referred to as "second PCU") 44. The battery 40 has a plurality of secondary battery cells and is configured to be rechargeable and dischargeable repeatedly. The secondary battery cells referred to here are not particularly limited, and for example, may be lithium-ion battery cells or nickel-metal hydride battery cells.

[0013] The first PCU 42 is a power conversion device and is interposed between the battery 40 and the drive motor 22. That is, the battery 40 is connected to the drive motor 22 via the first PCU 42. When the drive motor 22 functions as a prime mover, the first PCU 42 converts the DC power output from the battery 40 into three-phase AC power and supplies it to the drive motor 22. On the other hand, when the drive motor 22 functions as a generator, the first PCU 42 converts the three-phase AC power output from the drive motor 22 into DC power and supplies it to the battery 40. Thereby, the battery 40 is charged with the power generated by the drive motor 22. The specific configuration of the first PCU 42 is not particularly limited either. Although it is an example, the first PCU 42 in the present embodiment includes a voltage converter connected to the battery 40, an inverter located between the voltage converter and the drive motor 22, and a power controller that controls their operations. The voltage converter is configured to be able to step up and step down DC power, and the inverter is configured to be able to convert power between DC power and AC power.

[0014] The second PCU 44 is a power conversion device similar to the first PCU 42 and is interposed between the battery 40 and the charging motor 34. That is, the battery 40 is connected to the charging motor 34 via the second PCU 44. The second PCU 44 converts the three-phase AC power output from the charging motor 34 into DC power and supplies it to the battery 40. Thereby, the battery 40 is charged by the power generated by the charging motor 34. The specific configuration of the second PCU 44 is not particularly limited either. Although it is an example, the second PCU 44 in the present embodiment includes a voltage converter, an inverter, and a power controller, similar to the first PCU 42.

[0015] The hybrid vehicle 10 further includes a control device 50. The control device 50 is configured using a computer device and has a memory that stores various control programs, a processor that executes those control programs, and the like. The control device 50 acquires sensor signals from sensors 62 attached to the hybrid vehicle 10 and is configured to be able to control the operations of the engine 32, the first PCU 42, and the second PCU 44. The control device 50 acquires, via the sensors 62, for example, operation information by the user and vehicle information indicating the state of the hybrid vehicle 10. The operation information is, for example, accelerator opening information indicating the operation amount of the accelerator pedal by the user and brake pedal force information indicating the operation amount of the brake pedal by the user. The vehicle information is, for example, vehicle speed information indicating the speed of the hybrid vehicle 10 and battery information indicating the state of charge (SOC) of the battery 40. The vehicle information further includes various types of information necessary for executing the driving mode described later. The control device 50 controls the operations of each part of the hybrid vehicle 10 described above according to the input operation information and vehicle information.

[0016] The hybrid vehicle 10 further includes a display device 64. The display device 64 is a display configured to be able to display the maximum cruising speed. In this example, the display device 64 is a speedometer that displays the speed of the hybrid vehicle 10, and the maximum cruising speed is displayed superimposed on the speedometer. The maximum cruising speed will be described later.

[0017] The control device 50 can selectively execute at least a BEV mode and an HEV mode as driving modes of the hybrid vehicle 10. The BEV mode is a driving mode in which the wheels 14 are driven by the drive motor 22 without operating the engine 32. The HEV mode is a driving mode in which the engine 32 is operated while the drive motor 22 drives the wheels 14, power is generated by the power generation motor 34, and the battery 40 is charged with the generated power.

[0018] In the HEV mode, the control device 50 executes control to assist driving by displaying on the display device 64 the maximum cruising speed at which the vehicle can travel while maintaining the charge rate of the battery 40. FIG. 2 shows the processing of the driving assistance control in the HEV mode. As shown in FIG. 2, the control device 50 calculates the running resistance of the hybrid vehicle 10 from S10 to S14, calculates the maximum output of the engine 32 from S20 to S24, and based on the maximum output of the engine 32 and the running resistance of the hybrid vehicle 10 from S30 to S38, adjusts the maximum cruising speed displayed on the display device 64.

[0019] To calculate the running resistance of the hybrid vehicle 10 during running, the control device 50 detects the gradient of the road during running (S10) and detects the vehicle weight of the hybrid vehicle 10 (S12). The gradient of the road may be detected using a gradient sensor mounted on the hybrid vehicle 10 or may be detected from map information. The vehicle weight of the hybrid vehicle 10 may be detected using an acceleration sensor mounted on the hybrid vehicle 10. The control device 50 calculates the running resistance when traveling at the maximum cruising speed set as the initial value based on the gradient of the road and the vehicle weight of the hybrid vehicle 10 (S14).

[0020] To calculate the maximum output of the engine 32, the control device 50 detects the altitude during running (S20) and detects the intake air temperature (S22). The altitude may be detected using an atmospheric pressure sensor mounted on the hybrid vehicle 10, or may be detected from map information. The intake air temperature may be detected using an intake air temperature sensor mounted on the hybrid vehicle 10. The control device 50 calculates the maximum output of the engine 32 based on the altitude and the intake air temperature (S24).

[0021] The control device 50 calculates the power consumed by the drive motor 22 when the hybrid vehicle 10 travels with the calculated running resistance, and compares the power consumption with the maximum output of the engine 32 (S30). When the maximum output of the engine 32 is greater than the power consumption of the drive motor 22, it is possible to travel while sufficiently maintaining the charging rate of the battery 40 even when traveling at the current maximum cruising speed. In this case, the control device 50 increases the maximum cruising speed displayed on the display device 64 by a predetermined width (for example, several km / h) (S32). When the maximum output of the engine 32 is not greater than the power consumption of the drive motor 22, the control device 50 determines whether the maximum output of the engine 32 is equal to the power consumption of the drive motor 22 (S34). When the maximum output of the engine 32 is equal to the power consumption of the drive motor 22, it is possible to travel while maintaining the charging rate of the battery 40 even when traveling at the current maximum cruising speed. In this case, the control device 50 maintains the maximum cruising speed displayed on the display device 64 (S36). When the maximum output of the engine 32 is not equal to the power consumption of the drive motor 22, the charging rate of the battery 40 decreases when traveling at the current maximum cruising speed. In this case, the control device 50 decreases the maximum cruising speed displayed on the display device 64 by a predetermined width (for example, several km / h) (S38). The control device 50 can update the maximum cruising speed displayed on the display device 64 in real time by repeating the above processing in the HEV mode.

[0022] Figure 3 shows an example of the maximum cruising speed displayed on the display device 64. The speed range displayed in gray indicates the speed range in which the charge rate of the battery 40 decreases when driving within that speed range. That is, the minimum speed of the speed range displayed in gray indicates the maximum cruising speed. (a) is an example in which the hybrid vehicle 10 is driving on flat ground, and (b) is an example in which the hybrid vehicle 10 is driving on a slope. Since the running resistance when going uphill is high, the maximum cruising speed is lower than in the case of flat ground. The driver can drive the vehicle while maintaining the charge rate of the battery 40 by driving at a speed lower than the maximum cruising speed. Note that in the hybrid vehicle 10, the maximum cruising speed is displayed on the display device 64 for driving assistance, and the speed during driving is not limited to a speed lower than the maximum cruising speed. For example, if a vehicle speed limit is forcibly applied, it is possible to prevent the battery 40 from running out of power. However, when there is only a little distance left to the destination or when it is necessary to increase the vehicle speed urgently, etc., when the limit is not required, the freedom of use for the driver is reduced. On the other hand, in the hybrid vehicle 10, although the maximum cruising speed is displayed on the display device 64 for driving assistance, no vehicle speed limit is applied, so the freedom of use for the driver is ensured in the hybrid vehicle 10.

[0023] The hybrid vehicle 10 is not particularly limited, but for example, it may be a hybrid vehicle equipped with a REEV (Range Extender Electric Vehicle) system. In a hybrid vehicle equipped with a REEV system, an engine 32 with a small displacement is often adopted, and the maximum output of the drive motor 22 is larger than the maximum output of the engine 32. For this reason, in a hybrid vehicle equipped with a REEV system, the charge rate of the battery 40 may decrease in a high-speed driving state. If the decrease in the charge rate of the battery 40 continues, the power of the battery 40 will be exhausted, and ultimately the vehicle will not be able to drive. The technology disclosed in this specification can avoid such a situation, so it is particularly useful for hybrid vehicles equipped with a REEV system.

Explanation of Signs

[0024] 10: Hybrid vehicle, 14: Wheel, 18: Engine, 22: Driving motor, 32: Engine, 34: Charging motor, 40: Battery, 50: Control device, 62: Sensors, 64: Display device

Claims

[Claim 1] A hybrid vehicle, A battery; a first motor that drives wheels by using power supplied from the battery; The engine, a second motor that uses the power of the engine to generate electric power and charges the battery; A display device; a control device that, in a driving mode in which the first motor drives the wheels while the second motor generates electricity, calculates a maximum cruising speed at which the vehicle can be driven while maintaining the charge rate of the battery based on a maximum output of the engine and the running resistance of the vehicle, and displays the maximum cruising speed on the display device.

Images