Control device for hybrid vehicle

Abstract

To provide a control device for a hybrid vehicle that maintains comfort during automatic driving and prevents a decrease in the amount that a battery is charged.SOLUTION: When a vehicle speed V exceeds a predetermined background noise determination speed Va in a case where a vehicle travels in an automatic driving mode and a BEV priority traveling is selected, control for switching to an HEV traveling is performed. That is, when the BEV traveling is prioritized during the automatic driving and the vehicle speed V exceeds the predetermined background noise determination speed Va at which the background noise is large and influence on comfort is small, the HEV traveling by the driving of an engine 12 is actively performed, and a battery 24 can be charged by the driving of the engine 12. As a result, it is possible to provide the control device 50 for the hybrid vehicle 10 that maintains comfort during automatic driving and prevents a decrease in the amount that the battery is charged, SOC.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle.

Background Art

[0002] In a hybrid vehicle equipped with an engine and an electric motor as a power source for traveling, in recent years, for the automation of driving operations, the installation of various automatic driving modes has been promoted. In the hybrid vehicle, when shifting from a traveling state using only the motor to a hybrid traveling state in which the engine is driven, vibrations and noises generated at the start of the engine lead to a decrease in comfort (quietness). In particular, during traveling in an automatic driving mode where the driving operation is not performed and the behavior of the vehicle cannot be predicted, sensitivity to vibrations and noises increases. Therefore, a technique for setting the vehicle speed at which the engine starts according to various automatic driving modes has been disclosed. For example, the vehicle control device described in Patent Document 1 is such a device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the case of automatic driving, not only at the start of the engine, but also vibrations and noises in the hybrid traveling state in which the engine drive continues lead to a decrease in comfort (quietness). This is because vibrations and noises associated with engine drive increase compared to traveling using only the motor. In order to maintain comfort (quietness), it is desirable to increase traveling using only the motor. However, when traveling using only the motor is increased, the charge amount of the battery that drives the motor decreases, and when the engine is driven to charge the battery, conversely, problems such as impairment of comfort (quietness) have occurred.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for a hybrid vehicle that maintains comfort during automatic driving and suppresses a decrease in the charge amount of a battery.

Means for Solving the Problems

[0006] The gist of the first invention is as follows: (a) In a hybrid vehicle equipped with an engine and an electric motor as driving power sources, electric motor driving in which the engine is stopped and only the electric motor is used as the driving power source, and hybrid driving in which at least the engine among the driving power sources is used as the driving power source are switched based on a preset priority order. A control device, (b) comprising an automatic driving control unit for controlling the automatic driving of the vehicle, and (c) performing control to switch to the hybrid driving when the vehicle speed exceeds a predetermined quiet noise determination speed when driving in the automatic driving and the electric motor driving is set as a priority.

Effects of the Invention

[0007] According to the first invention, when driving in the automatic driving and the electric motor driving is set as a priority, control is performed to switch to the hybrid driving when the vehicle speed exceeds a predetermined quiet noise determination speed. That is, during driving that prioritizes the automatic driving and the electric motor driving, when the vehicle speed exceeds a predetermined quiet noise determination speed at which the quiet noise is large and has little influence on comfort, the hybrid driving in which the engine is actively driven is performed, and the battery can be charged by driving the engine. Thereby, a control device for a hybrid vehicle that maintains comfort during the automatic driving and suppresses a decrease in the charge amount of the battery can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment

[0010] FIG. 1 is a diagram for explaining the schematic configuration of a hybrid vehicle 10 to which the present invention is applied, and is also a diagram for explaining the main parts of control functions and control systems for various controls in the hybrid vehicle 10. The hybrid vehicle 10 includes an engine 12, an electric differential unit 14, and an automatic transmission 16 in series. The output of the engine 12 is controlled by an engine output control device 40. The electric differential unit 14 is a unit that constitutes a known hybrid vehicle, and an engine 12, a first electric motor MG1, and a second electric motor MG2 are connected to an internal planetary gear device 18. Also, the electric differential unit 14 and the automatic transmission 16 are connected by an intermediate transmission member 20. Since the electric differential unit 14 and the automatic transmission 16 are configured substantially symmetrically with respect to their axial centers, the lower half is omitted in FIG. 1.

[0011] Both the first electric motor MG1 and the second electric motor MG2 have functions as an electric motor and a generator, are connected to a battery 24 that can be charged and discharged via an inverter 22, and their respective motor torques are controlled by an electronic control device 50 described later. The engine 12, the electric differential unit 14, and the second electric motor MG2 function as power sources of the hybrid vehicle 10.

[0012] The automatic transmission 16 is a known planetary gear type stepped transmission, and the power from the intermediate transmission member 20 is shifted by the control of a hydraulic control circuit 42 and output from an output shaft 32. The output shaft 32 is connected to left and right drive wheels 36 via a final reduction gear 34.

[0013] The hybrid vehicle 10 is provided with an automatic braking system 44 and an automatic steering system 46. The automatic braking system 44 controls the braking force of each wheel brake 38 provided on the drive wheels 36 and driven wheels (non-drive wheels) (not shown), and the automatic steering system 46 controls the steering angle Φ in accordance with control from an electronic control unit 50 described later.

[0014] The electronic control unit 50 functions as a controller that performs various controls of the hybrid vehicle 10, and is configured to include a so-called microcomputer.

[0015] An output rotation speed sensor 76, an accelerator operation amount sensor 80, a steering angle sensor 82, and a battery charge amount sensor 96 are connected to the electronic control unit 50, and signals representing the rotation speed of the output shaft 32 (output rotation speed) Nout, the depression operation amount of the accelerator pedal (accelerator operation amount) Acc, the steering angle Φ, and the battery charge amount SOC of the battery 24 are supplied thereto. The output rotation speed Nout corresponds to the vehicle speed V.

[0016] The auto cruise setting switch 84 is a device for selecting a cruise driving mode for performing constant speed driving or following driving without requiring the driver's acceleration or deceleration operation, setting a target vehicle speed VtC, setting a target inter-vehicle distance DtC during following driving, and the like. The navigation system 86 is a device equipped with map information for displaying or setting a driving route according to a destination, and acquiring various road traffic information such as the vehicle's own position, traffic jams, roads, gradients, altitudes, legal speeds, and weather by GPS, VICS (registered trademark) (Vehicle Information and Communication System; Road Traffic Information and Communication System), etc. The radar 88 is a device for detecting the inter-vehicle distance between the preceding vehicle and the following vehicle, nearby pedestrians, or the distance to an obstacle. The camera 90 is a device for photographing the front, rear, sides, etc. of the vehicle. The automatic driving switch 92 is a switch for selecting an automatic driving mode in which the driving force and steering angle Φ of the vehicle are automatically controlled to drive. The BEV priority switch 94 is a switch for selecting a BEV priority driving that gives priority to motor driving (hereinafter referred to as BEV driving) in which the engine 12 is stopped and only the second motor MG2 drives. Signals representing the respective information about the above devices and switches are also supplied to the electronic control unit 50.

[0017] From the electronic control unit 50, an engine control signal Se is output to the engine output control device 40 that controls the engine output, a motor control signal Sm is output to the inverter 22 that controls the first motor MG1 and the second motor MG2, a shift control signal Sa is output to the hydraulic control circuit 42 that controls the shift of the automatic transmission 16, a brake control signal Sb is output to the automatic brake system 44, and a steering angle control signal Sr is output to the automatic steering system 46.

[0018] The electronic control unit 50 functionally includes a hybrid control unit 52, a stepped shift control unit 54, a steering control unit 56, a brake control unit 58, an automatic driving control unit 60, and a cruise driving mode control unit 62.

[0019] The automatic driving control unit 60 selects the automatic driving mode and calculates the target driving force Ft2, target steering angle Φt, target braking force Bt, etc. during automatic driving. The automatic driving modes include a cruise driving mode in which constant-speed driving or following driving is performed without requiring the driver's acceleration or deceleration operation, and an automatic driving mode in which the driving force and steering angle Φ of the vehicle are automatically controlled to drive. The cruise driving mode is selected by operating the auto cruise setting switch 84, and the automatic driving mode is selected by operating the automatic driving switch 92. For example, when both are selected, the selection of the automatic driving mode takes precedence.

[0020] In the cruise driving mode control unit 62, the target vehicle speed VtC and the target inter-vehicle distance DtC are set by operating the auto cruise setting switch 84. The cruise driving mode control unit 62 calculates the target driving force FtC by feedback control or the like so that the actual inter-vehicle distance D from the preceding vehicle detected by the radar 88 becomes the target inter-vehicle distance DtC, and supplies the target vehicle speed VtC and the target driving force FtC to the automatic driving control unit 60.

[0021] The automatic driving control unit 60 functionally includes a travel plan generation unit 110 and a travel control unit 130 as shown in FIG. 2 with respect to the drive system. The travel plan generation unit 110 includes a target vehicle speed calculation unit 112, a vehicle speed safety margin calculation unit 114, a target inter-vehicle distance calculation unit 116, and an actual inter-vehicle distance calculation unit 118. Information such as vehicle position information, map information such as roads, gradients, altitudes, legal speeds, travel routes and courses, and weather is supplied to the target vehicle speed calculation unit 112 from the navigation system 86. The target vehicle speed calculation unit 112 sequentially sets the base target vehicle speed Vt1 when performing automatic driving based on this information. The target vehicle speed calculation unit 112 is configured to receive the target vehicle speed VtC during constant-speed driving from the cruise driving mode control unit 62, and sets the target vehicle speed VtC as the target vehicle speed Vt1 in the cruise driving mode.

[0022] The vehicle speed safety margin calculation unit 114 obtains the vehicle speed safety margin Vm according to the difference between the target inter-vehicle distance Dref determined by the target inter-vehicle distance calculation unit 116 and the actual inter-vehicle distance D calculated based on signals from the radar 88 and the like by the actual inter-vehicle distance calculation unit 118. The target vehicle speed Vt2 is calculated by subtracting the vehicle speed safety margin Vm from the target vehicle speed Vt1. The target inter-vehicle distance Dref and the actual inter-vehicle distance D are the inter-vehicle distances from the preceding vehicle. The target inter-vehicle distance Dref is set according to the current vehicle speed V and the like so that a sufficient distance to avoid a collision with the preceding vehicle can be achieved. When the actual inter-vehicle distance D is greater than the target inter-vehicle distance Dref, in order to prevent the vehicle speed V from rising unnecessarily, the vehicle speed safety margin Vm is lower-guarded at 0.

[0023] The driving control unit 130 includes a feed-forward (F / F) control calculation unit 132, a feedback (F / B) control calculation unit 134, a running resistance calculation unit 136, a driving force adjustment unit 138, and a target braking force calculation unit 140. The F / F control calculation unit 132 calculates the FF driving force value Fff required to travel at the target vehicle speed Vt2 according to a predetermined feed-forward control formula or the like. The F / B control calculation unit 134 calculates the FB correction value Ffb according to a predetermined feedback control formula or the like based on the deviation ΔV between the target vehicle speed Vt2 and the current vehicle speed V. Further, the running resistance calculation unit 136 calculates the running resistance Fr based on the vehicle's load (R / L), road gradient, number of passengers, load weight, etc., and calculates the base target driving force Ft1 by adding the FF driving force value Fff, the FB correction value Ffb, and the running resistance Fr. The load may be set in advance in the navigation system 86 or the like.

[0024] The driving force adjustment unit 138 adjusts the target driving force Ft1 to set the final target driving force Ft2. In the cruise mode, the target driving force FtC supplied from the cruise mode control unit 62 is used as the base target driving force Ft1.

[0025] The target driving force Ft2 is supplied to the target braking force calculation unit 140 and output to the hybrid control unit 52 and the stepped transmission control unit 54. When the target driving force Ft2 is negative (minus), the target braking force calculation unit 140 calculates the target braking force Bt of the wheel brake 38 at which the target driving force Ft2 can be obtained in combination with the power source brake generated by the hybrid control unit 52, and outputs it to the brake control unit 58. By controlling the automatic braking system 44 according to this target braking force Bt, the wheel brake 38 is operated with the target braking force Bt, and the target driving force Ft2 can be obtained in combination with the power source brake obtained by the control of the hybrid control unit 52.

[0026] The hybrid control unit 52 switches between BEV driving (motor driving) in which the engine 12 is stopped and only the second motor MG2 is used as the power source, and hybrid driving (hereinafter referred to as HEV driving) in which the engine 12 is driven and the engine 12 is used as all or part of the power source and the battery 24 is charged with the generated power of the first motor MG1 that generates reaction torque. The switching between BEV driving and HEV driving is preferably performed by a preset determination formula based on, for example, the selection state of the BEV priority switch 94, the battery charge amount SOC, the vehicle speed V, and the target driving force Ft2 supplied from the automatic driving control unit 60.

[0027] The hybrid control unit 52 outputs an engine control signal Se to the engine output control device 40 that controls the engine 12 and a motor control signal Sm to the inverter 22 that controls the first motor MG1 and the second motor MG2 so that the vehicle is driven by the target driving force Ft2 along with the switching between BEV driving and HEV driving. Further, when the vehicle is traveling in the automatic driving mode and BEV priority driving is selected, the hybrid control unit 52 switches to HEV driving when the vehicle speed V exceeds a predetermined quiet noise determination speed Va.

[0028] The stepped shift control unit 54 transmits a shift control signal Sa to the hydraulic control circuit 42 to establish the target gear position obtained according to a predetermined shift map, and performs shift control of the automatic transmission 16. The shift map is set based on, for example, the target driving force Ft2 and the vehicle speed V.

[0029] When the automatic driving mode is selected, the steering control unit 56 transmits a steering angle control signal Sr to the automatic steering system 46 so as to achieve the target steering angle Φt supplied from the automatic driving control unit 60. The target steering angle Φt is determined based on road information and the like, and is appropriately set according to the vehicle speed V, the driving force, etc. for traveling along a predetermined driving route, for example, or for traveling along a lane detected by the camera 90 or switching lanes.

[0030] The brake control unit 58 transmits a brake control signal Sb to the automatic brake system 44 so that the wheel brake 38 is operated with the target brake force Bt supplied from the automatic driving control unit 60. The target brake force Bt is appropriately set so as to decelerate at a predetermined deceleration by the target inter-vehicle distance calculation unit 116, the actual inter-vehicle distance calculation unit 118, the vehicle speed safety margin calculation unit 114, the target brake force calculation unit 140, etc. shown in FIG. 2.

[0031] By the way, when traveling in the automatic driving mode and BEV priority driving is selected by the BEV priority switch 94 for improving comfort, the state of charge SOC of the battery decreases during continuous BEV driving, and for charging the battery, the engine 12 is driven and the vehicle switches to HEV driving, resulting in a problem that the comfort is conversely impaired due to an increase in vibration and noise of the engine 12.

[0032] When the electronic control device 50 of this embodiment is traveling in the automatic driving mode and BEV priority driving is selected, it maintains comfort and suppresses a decrease in the state of charge SOC of the battery by the control operation described in the flowchart of FIG. 3.

[0033] First, in step S10 corresponding to the automatic driving control unit 60 (hereinafter, steps are omitted), it is determined whether it is in the automatic driving mode. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, then in S20 corresponding to the hybrid control unit 52, it is determined whether BEV priority driving is selected by the BEV priority switch 94. If the determination in S20 is negative, this routine is terminated. If the determination in S20 is positive, then in S30 corresponding to the hybrid control unit 52, it is determined whether the vehicle speed V exceeds a predetermined noise determination speed Va at which there is little impact on comfort and the background noise is large. If the determination in S30 is negative, this routine is terminated. If the determination in S30 is positive, then in S40 corresponding to the hybrid control unit 52, the engine is driven and the vehicle is switched to HEV driving. Next, in S50, an electric motor control signal is sent to the inverter 22, and charging of the battery 24 using the first electric motor MG1 as a generator is started, and this routine is terminated.

[0034] As described above, according to this embodiment, when driving in the automatic driving mode and BEV priority driving is selected, when the vehicle speed V exceeds the predetermined noise determination speed Va, control is performed to switch to HEV driving. That is, when BEV driving is prioritized during automatic driving and the vehicle speed V exceeds the predetermined noise determination speed Va at which the noise is large and there is little impact on comfort, HEV driving by actively driving the engine 12 is performed, and the battery 24 can be charged by driving the engine 12. Thereby, a control device for a hybrid vehicle 10 that maintains comfort during automatic driving and suppresses a decrease in the battery charge amount SOC can be provided.

[0035] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0036] 10: Hybrid vehicle 12: Engine 50: Electronic control unit (control unit) MG2: Second motor V: Vehicle speed Va: Noise determination speed

Claims

【Claim 1】 In a hybrid vehicle equipped with an engine and an electric motor as a power source for running, a control device that switches between electric motor running in which the engine is stopped and only the electric motor is used as the power source and hybrid running in which at least the engine among the power sources is used as the power source based on a preset priority order, comprising an automatic driving control unit that controls the automatic driving of the vehicle, A control device for a hybrid vehicle, characterized in that when running in the automatic driving and electric motor running is set as a priority, control is performed to switch to the hybrid running when the vehicle speed exceeds a predetermined quiet noise determination speed.

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