Driving force setting method and driving force setting device

Abstract

To achieve desired acceleration without increasing the size of a motor even in an electric vehicle without a speed change gear when the electric vehicle enters an expressway and requires high acceleration. [Solution] The driving force setting device 1 acquires a reference driving force map that defines the relationship between accelerator opening and driving force when the electric vehicle is running normally, sets the driving force of the electric vehicle according to the acquired reference driving force map, and when the electric vehicle enters a highway, changes to an assist driving force map that defines the relationship between accelerator opening and driving force when the electric vehicle is running on a highway, and sets the driving force of the electric vehicle according to the changed assist driving force map, with the driving force of the assist driving force map being set higher than the driving force of the reference driving force map.

Description

[Technical Field]

[0001] The present invention relates to a driving force setting method and a driving force setting device. [Background technology]

[0002] Conventionally, a vehicle transmission control device that controls an automatic transmission mechanism that transmits driving force from a drive source to drive wheels is disclosed in Patent Document 1. The vehicle transmission control device disclosed in Patent Document 1 detects that the vehicle is going around a corner, and when it detects the driver's intention to accelerate, it changes the gear ratio of the automatic transmission mechanism to achieve the acceleration intended by the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-46174 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional vehicle transmission control device described above, the gear ratio of the automatic transmission mechanism is changed to achieve the acceleration intended by the driver, but electric vehicles do not have transmission gears, so the conventional method cannot be used. However, even electric vehicles require high acceleration when traveling on expressways, such as when merging onto a highway, so it is necessary to achieve the desired acceleration. However, because electric vehicles do not have transmission gears, achieving high acceleration requires a large motor, which is a problem.

[0005] Therefore, an object of the present invention is to provide a driving force setting method and device that can achieve the desired acceleration when an electric vehicle enters a highway and requires high acceleration, even in an electric vehicle without a transmission gear, without increasing the size of the motor. [Means for solving the problem]

[0006] A driving force setting method and device according to one aspect of the present invention acquires a reference driving force map that defines the driving force during normal driving, sets the driving force of an electric vehicle in accordance with the acquired reference driving force map, and when the electric vehicle enters a highway, changes to an assist driving force map that defines the driving force when driving on a highway, and sets the driving force of the electric vehicle in accordance with the changed assist driving force map, with the driving force of the assist driving force map being set higher than the driving force of the reference driving force map. [Effects of the Invention]

[0007] According to the present invention, when an electric vehicle enters a highway and requires high acceleration, the desired acceleration can be achieved without increasing the size of the motor, even in an electric vehicle without a transmission gear. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the configuration of a driving force setting device according to an embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a reference driving force map used in the driving force setting device according to one embodiment. [Figure 3] FIG. 3 is a diagram showing an example of an assist driving force map used in the driving force setting device according to one embodiment. [Figure 4] FIG. 4 is a flowchart showing the processing procedure of the driving force setting process performed by the driving force setting device according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A driving force setting method and a driving force setting device according to this embodiment will be described below with reference to the drawings. In the description of the drawings, the same parts are given the same reference numerals and detailed description will be omitted.

[0010] [Configuration of the driving force setting device] The configuration of a driving force setting device according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of the driving force setting device. As shown in Fig. 1, the driving force setting device 1 includes a control unit 3 and a storage unit 5. The driving force setting device 1 is also connected to a navigation device 11, an accelerator sensor 13, a steering angle sensor 15, and a vehicle speed sensor 17, all of which are installed in the electric vehicle.

[0011] The driving force setting device 1 is mounted on an electric vehicle and sets the driving force of the electric vehicle in accordance with the accelerator pedal position. In particular, the driving force setting device 1 sets the driving force of the electric vehicle so that the desired acceleration can be achieved on a curve when the electric vehicle enters a highway and merges into a driving lane. The driving force setting device 1 is provided in an ECU (electronic control unit) that controls the motor of the electric vehicle.

[0012] The control unit 3 is a controller that sets the driving force of the electric vehicle according to the accelerator pedal position. Specifically, the control unit 3 acquires a reference driving force map that defines the driving force during normal driving, and sets the driving force of the electric vehicle according to the acquired reference driving force map. When the electric vehicle enters an expressway, the control unit 3 changes to an assist driving force map that defines the driving force when driving on an expressway, and sets the driving force of the electric vehicle according to the changed assist driving force map. Here, the driving force of the assist driving force map is set higher than the driving force of the reference driving force map.

[0013] The storage unit 5 is a memory or database that stores information necessary to execute the driving force setting process. Specifically, the storage unit 5 stores a reference driving force map and an assist driving force map. In addition, the storage unit 5 may store map information for determining whether the electric vehicle has entered an expressway.

[0014] The reference driving force map defines the relationship between accelerator opening and driving force during normal driving of an electric vehicle. Specifically, Fig. 2 shows an example of the reference driving force map. As shown in Fig. 2, the driving force of the electric vehicle increases at a constant rate as the accelerator opening increases, and reaches a maximum driving force Fm when the accelerator opening is Am.

[0015] The assist driving force map defines the relationship between accelerator opening and driving force when the electric vehicle is traveling on a highway. The driving force in the assist driving force map is set higher than the driving force in the reference driving force map. Specifically, FIG. 3 is a diagram showing an example of the assist driving force map.

[0016] As shown in Fig. 3, the driving force in the assist driving force map increases in the same manner as the reference driving force map in the range below a predetermined accelerator opening Ac. On the other hand, the driving force in the assist driving force map is set higher than the driving force in the reference driving force map in the range above the predetermined accelerator opening Ac. In other words, the rate at which the driving force increases in the assist driving force map is set higher than in the reference driving force map.

[0017] Therefore, in the reference driving force map, the maximum driving force Fm is reached when the accelerator pedal depression is Am, whereas in the assist driving force map, the maximum driving force Fm is reached when the accelerator pedal depression is An, which is smaller than Am. Therefore, in the assist driving force map, a large driving force can be set even when the accelerator pedal depression is small.

[0018] Furthermore, when the accelerator opening of the electric vehicle becomes equal to or greater than a predetermined accelerator opening Ac and the driving force of the electric vehicle becomes higher than the driving force in the reference driving force map, the control unit 3 notifies the driver of the electric vehicle. For example, an indicator light indicating that the assist function is ON is provided on the instrument panel, and the control unit 3 notifies the driver by turning on this indicator light.

[0019] The predetermined accelerator opening Ac is set, for example, to correspond to the range of accelerator opening used when the electric vehicle enters a highway and goes around a curve to merge into a driving lane. Therefore, when the driver opens the accelerator when going around a curve to merge into a driving lane on the highway, the accelerator opening will be close to Ac, and when the driver opens the accelerator, a high driving force is set in the assist driving force map, thereby achieving the desired acceleration.

[0020] The navigation device 11 is mounted on the electric vehicle and detects the current position information of the electric vehicle and outputs it to the driving force setting device 1. The accelerator sensor 13 detects the accelerator opening of the electric vehicle. The steering angle sensor 15 detects the steering angle of the steering wheel of the electric vehicle. The vehicle speed sensor 17 detects the speed of the electric vehicle. The driving force setting device 1 acquires data from these sensors and records it in the memory unit 5.

[0021] The driving force setting device 1 is a computer configured with general-purpose electronic circuits including a microcomputer, a microprocessor, and a CPU, as well as peripheral devices such as memory, and is installed with a computer program for executing a driving force setting process. Each function of the driving force setting device 1 can be implemented by one or more processing circuits. The processing circuit may include, for example, a programmed processing device including electrical circuits, and may also include devices such as application-specific integrated circuits (ASICs) or conventional circuit components arranged to perform the functions described in the embodiments.

[0022] [Driving force setting process] Next, a description will be given of the driving force setting process performed by the driving force setting device 1 according to this embodiment. Fig. 4 is a flowchart showing the processing steps of the driving force setting process. The driving force setting process shown in Fig. 4 starts when the power supply of the electric vehicle is turned on.

[0023] 4, in step S101, the control unit 3 acquires a reference driving force map from the storage unit 5. The reference driving force map is a map for normal driving, and is therefore acquired when the electric vehicle is powered on and starts to drive.

[0024] In step S103, the control unit 3 sets the driving force of the electric vehicle in accordance with the reference driving force map acquired in step S101. Then, while the electric vehicle is traveling normally on an open road, the control unit 3 sets the driving force of the electric vehicle in accordance with the reference driving force map. The set driving force is output to the ECU that controls the motor.

[0025] In step S105, the control unit 3 determines whether or not the electric vehicle will enter an expressway based on the position information of the electric vehicle acquired from the navigation device 11. If the electric vehicle will enter an expressway, the process proceeds to step S107, and if the electric vehicle will not enter an expressway, the process proceeds to step S123.

[0026] Specifically, the control unit 3 compares the position information of the electric vehicle with the map information, and if the electric vehicle has reached the entrance to the expressway, determines that the electric vehicle will enter the expressway, and if the electric vehicle has not reached the entrance to the expressway, determines that the electric vehicle will not enter the expressway.

[0027] In step S107, the control unit 3 determines whether the accelerator opening of the electric vehicle is less than a predetermined accelerator opening or whether the electric vehicle is stopped. For example, it determines whether the accelerator opening of the electric vehicle is less than 35% or the speed of the electric vehicle is less than 2 km / h. In other words, it determines whether the electric vehicle has decelerated at the entrance to a highway or has stopped at a toll gate.

[0028] If the accelerator opening of the electric vehicle is less than 35% or the speed of the electric vehicle is less than 2 km / h, the process proceeds to step S109. That is, a change to the assist driving force map in step S111, which will be described later, is permitted. On the other hand, if the accelerator opening of the electric vehicle is 35% or more and the speed of the electric vehicle is 2 km / h or more, it is determined whether the accelerator opening of the electric vehicle continues to be less than a predetermined accelerator opening or whether the electric vehicle is stopped.

[0029] In step S109, the control unit 3 determines whether the steering angle of the electric vehicle is greater than a predetermined value. For example, it determines whether the steering angle of the electric vehicle is greater than 90°. That is, it determines whether the electric vehicle has passed the entrance to the expressway and is entering a curve where it will merge into the driving lane. If the steering angle is greater than 90°, the process proceeds to step S111. That is, a change to the assist driving force map in step S111 is permitted. On the other hand, if the steering angle is 90° or less, the process proceeds to step S115.

[0030] In step S111, the control unit 3 changes the reference driving force map to the assist driving force map because the electric vehicle is entering an expressway. This allows the control unit 3 to set the driving force according to the assist driving force map when the electric vehicle passes the entrance to the expressway and travels around a curve that merges into a driving lane. Therefore, even when the electric vehicle is entering and turning around a curve that merges into a driving lane on the expressway, and the accelerator pedal opening degree cannot be increased, the desired acceleration can be achieved.

[0031] In this embodiment, the map is changed to the assist driving force map when the conditions of steps S107 and S109 are met, but the processes of steps S107 and S109 do not have to be performed. That is, the map may be changed to the assist driving force map simply when it is determined in step S105 that the vehicle will enter an expressway. Furthermore, the map may be changed to the assist driving force map when either the condition of step S107 or step S109 is met.

[0032] In step S113, the control unit 3 sets the driving force of the electric vehicle according to the assist driving force map changed in step S111. Then, while the electric vehicle is traveling on the expressway, the control unit 3 sets the driving force according to the assist driving force map. The set driving force is output to the ECU that controls the motor.

[0033] In step S115, the control unit 3 determines whether or not the electric vehicle has exited the expressway based on the position information of the electric vehicle acquired from the navigation device 11. If the electric vehicle has exited the expressway, the process proceeds to step S117, and if the electric vehicle has not exited the expressway, the process returns to step S107.

[0034] Specifically, the control unit 3 compares the position information of the electric vehicle with the map information, and if the electric vehicle has passed an exit of the expressway, determines that the electric vehicle has exited the expressway, whereas if the electric vehicle has not passed an exit of the expressway, determines that the electric vehicle has not exited the expressway.

[0035] In this embodiment, the assist driving force map is used to set the driving force while the electric vehicle is traveling on the expressway, but the assist driving force map may be used only near the entrance to the expressway. In that case, in step S115, the control unit 3 may determine whether the electric vehicle has passed through a curve that merges into the driving lane of the expressway and entered the driving lane.

[0036] In step S117, the control unit 3 determines whether the accelerator opening of the electric vehicle is less than a predetermined accelerator opening. For example, it determines whether the accelerator opening of the electric vehicle is less than 35%. If the accelerator opening of the electric vehicle is less than 35%, the process proceeds to step S119, but if the accelerator opening of the electric vehicle is 35% or more, it continues to determine whether the accelerator opening of the electric vehicle is less than the predetermined accelerator opening.

[0037] In step S119, since the electric vehicle has exited the expressway, the control unit 3 changes the assist driving force map to the reference driving force map. This allows the control unit 3 to set the driving force according to the reference driving force map when the electric vehicle passes the expressway exit and returns to normal driving.

[0038] In step S121, the control unit 3 sets the driving force of the electric vehicle in accordance with the reference driving force map changed in step S119. Then, while the electric vehicle is traveling normally on an open road, the control unit 3 sets the driving force in accordance with the reference driving force map. The set driving force is output to the ECU that controls the motor.

[0039] In step S123, the control unit 3 determines whether the power supply to the electric vehicle has been turned off, and if it has not been turned off, the process returns to step S105, and if it has been turned off, the driving force setting process according to this embodiment is terminated.

[0040] [Effects of the embodiment] As described above in detail, the driving force setting device 1 according to this embodiment acquires a reference driving force map that defines the driving force during normal driving, and sets the driving force of the electric vehicle according to the acquired reference driving force map. When the electric vehicle enters a highway, the driving force setting device 1 changes to an assist driving force map that defines the driving force for highway driving, and sets the driving force of the electric vehicle according to the changed assist driving force map. The driving force in the assist driving force map is set higher than the driving force in the reference driving force map. This allows the electric vehicle to achieve the desired acceleration when entering a highway and requiring high acceleration, even in an electric vehicle without a transmission, without increasing the size of the motor.

[0041] Furthermore, the driving force setting device 1 according to this embodiment determines whether or not the electric vehicle will enter an expressway based on the position information of the electric vehicle. This makes it possible to determine with high accuracy whether or not the electric vehicle will enter an expressway using the position information output from the navigation device 11.

[0042] Furthermore, in the driving force setting device 1 according to this embodiment, the driving force in the assist driving force map is set higher than the driving force in the reference driving force map in a range of accelerator openings equal to or greater than a predetermined value. This allows the driving force to be set high only at high accelerator openings used during high-speed driving, eliminating the need to set an unnecessarily high driving force and enabling the electric vehicle to be driven efficiently.

[0043] Furthermore, the driving force setting device 1 according to this embodiment notifies the driver of the electric vehicle when the accelerator opening of the electric vehicle reaches a predetermined accelerator opening or more and the driving force of the electric vehicle becomes higher than the driving force in the reference driving force map. This allows the driver to recognize that a driving force higher than the driving force during normal driving has been set, preventing the driver from feeling uncomfortable.

[0044] Furthermore, the driving force setting device 1 according to this embodiment allows a change to the assist driving force map when the accelerator opening of the electric vehicle is less than a predetermined accelerator opening. This allows a change to the assist driving force map when the driving force is the same as that of the reference driving force map, preventing the driver from feeling uncomfortable due to the change in driving force.

[0045] Furthermore, the driving force setting device 1 according to this embodiment allows a change to the assist driving force map when the electric vehicle is stopped. This allows a change to the assist driving force map when the electric vehicle is stopped, preventing the driver from feeling uncomfortable due to a change in driving force.

[0046] Furthermore, the driving force setting device 1 according to this embodiment allows a change to the assist driving force map when the steering angle of the electric vehicle is greater than a predetermined value. This allows accurate detection of the electric vehicle entering a curve that merges into the driving lane, and enables a change to the assist driving force map.

[0047] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure. [Explanation of symbols]

[0048] 1. Driving force setting device 3. Control Unit 5 Storage section 11 Navigation devices 13 Accelerator sensor 15 Steering angle sensor 17 Vehicle speed sensor

Claims

1. A driving force setting method by a controller that sets the driving force of an electric vehicle in accordance with an accelerator opening, comprising: obtaining a reference driving force map that defines the relationship between accelerator opening and driving force during normal driving of the electric vehicle; setting a driving force of the electric vehicle in accordance with the acquired reference driving force map; When the electric vehicle enters an expressway, the map is changed to an assist driving force map that defines the relationship between accelerator opening and driving force when the electric vehicle is traveling on an expressway; setting a driving force of the electric vehicle in accordance with the changed assist driving force map; The driving force of the assist driving force map is set higher than the driving force of the reference driving force map. How to set the driving force.

2. Based on the position information of the electric vehicle, it is determined whether the electric vehicle will enter an expressway. The driving force setting method according to claim 1 .

3. The driving force of the assist driving force map is set higher than the driving force of the reference driving force map in a range of a predetermined accelerator opening or more. The driving force setting method according to claim 1 .

4. When the accelerator opening of the electric vehicle becomes equal to or greater than the predetermined accelerator opening and the driving force of the electric vehicle becomes higher than the driving force of the reference driving force map, a notification is given to the driver of the electric vehicle. The driving force setting method according to claim 3 .

5. When an accelerator opening degree of the electric vehicle is less than the predetermined accelerator opening degree, a change to the assist drive force map is permitted. The driving force setting method according to claim 3 .

6. When the electric vehicle is stopped, a change to the assist drive force map is permitted. The driving force setting method according to claim 1 .

7. When the steering angle of the electric vehicle is greater than a predetermined value, a change to the assist drive force map is permitted. The driving force setting method according to claim 1 .

8. A driving force setting device including a controller that sets the driving force of an electric vehicle in accordance with an accelerator opening, obtaining a reference driving force map that defines the relationship between accelerator opening and driving force during normal driving of the electric vehicle; setting a driving force of the electric vehicle in accordance with the acquired reference driving force map; When the electric vehicle enters an expressway, the map is changed to an assist driving force map that defines the relationship between accelerator opening and driving force when the electric vehicle is traveling on an expressway; setting a driving force of the electric vehicle in accordance with the changed assist driving force map; The driving force of the assist driving force map is set higher than the driving force of the reference driving force map. Driving force setting device.

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