JP2015072044A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device which stops and restarts an engine while monitoring a drive state of a vehicle in accordance with deceleration required by a driver, a slip rate and a road surface friction coefficient.SOLUTION: A vehicle control device comprises: brake operation amount detection means which detects a brake operation amount of a driver; required deceleration calculation means which calculates required deceleration by the driver from output of the brake operation amount detection means; and coasting control determination means which determines continuation or cancellation of coasting operation in accordance with the required deceleration while a vehicle is coasting.

Description

  The present invention relates to a vehicle control device provided with an engine automatic start / stop means for automatically stopping and restarting an engine during coasting according to a driver's requested deceleration.

  In recent years, as one of the measures to improve the fuel efficiency of a vehicle equipped with an internal combustion engine (engine), coasting (inertial running) is performed by disengaging a clutch arranged between the engine and the drive wheel during vehicle running. Technologies that reduce drag resistance and improve fuel efficiency have been developed.

  As an engine automatic start / stop device, for example, a technique disclosed in JP-A-7-266932 (Patent Document 1) is known. According to the technique disclosed in Patent Document 1, the engine is automatically started and stopped and the start clutch is engaged during deceleration when only a small torque is required while the vehicle is running. Combustion consumption during slow deceleration operation can be avoided, fuel efficiency can be improved, and a smooth running feeling can be obtained.

  Further, as a vehicle engine automatic control device, for example, a technique disclosed in JP2013-117216A (Patent Document 2) is known. According to the technique disclosed in Patent Document 2, the engine can be stopped and restarted during coasting according to the amount of brake operation by the driver, and vehicle braking can be smoothed.

JP-A-7-266932 JP 2013-117216 A

  Since the conventional device has a configuration in which the engine is stopped and restarted according to the brake operation amount after the engine is stopped, there is a possibility that the configuration for stopping and restarting the engine according to the deceleration may not be realized. . For example, when it is considered that the time to stop during a sudden deceleration during coasting is short, if the coasting is canceled by operating the brake, the engine will drive and the engine and wheels will not be secured without ensuring the stability of the vehicle. There is a risk of connecting.

  In addition, even when the coasting is canceled by a minute brake operation after the engine is stopped, there is a concern about generation of driving force not intended by the driver and deterioration of fuel consumption.

  In order to solve the above-described problems, the present invention provides a vehicle control device that stops and restarts an engine while monitoring a driving state of the vehicle according to a deceleration, a slip ratio, and a road surface friction coefficient requested by a driver. The purpose is to obtain.

  The vehicle control apparatus according to the present invention includes a brake operation amount detection unit that detects a driver's brake operation amount, a request deceleration calculation unit that calculates the driver's request deceleration from an output of the brake operation amount detection unit, and Coasting control determination means for determining whether to continue or cancel the coasting according to the required deceleration while the vehicle is traveling on the coast is provided.

  According to the vehicle control apparatus of the present invention, by stopping and restarting the engine according to the deceleration requested by the driver, it is possible to improve the braking performance of the vehicle and smooth the braking. Further, since the control of the vehicle does not respond to the minute brake operation, it is possible to prevent generation of driving force not intended by the driver and to improve fuel efficiency.

1 is a system configuration diagram illustrating a vehicle control device according to Embodiment 1 of the present invention. FIG. It is a flowchart figure which shows the engine automatic stop and restart control process of the control apparatus of the vehicle by Embodiment 1 of this invention. It is a figure which shows the road surface friction coefficient-slip ratio characteristic used for determination whether the whole vehicle is in the unstable state in control by the control apparatus of the vehicle of Embodiment 1 of this invention.

  A preferred embodiment of a vehicle control apparatus according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
1 is a system configuration diagram illustrating a vehicle control apparatus according to Embodiment 1 of the present invention. In FIG. In FIG. 1, a torque converter 2 is provided on the output side of an engine 1 that is an internal combustion engine. A belt type continuously variable transmission 4 including a starting clutch 3 is connected to the output side of the torque converter 2. The rotational driving force output from the engine 1 is input to the belt-type continuously variable transmission 4 including the starting clutch 3 through the torque converter 2, and is transmitted to the drive wheels 5 after being shifted by a desired gear ratio. .

  Here, in FIG. 1, the mechanism for transmitting the output rotational driving force between the engine 1 and the drive wheels 5 is a belt type continuously variable transmission 4 including the torque converter 2 and the starting clutch 3. As long as it has the function of the starting clutch 3 that separates the clutch 5, a mechanism combining a clutch and a motor or a dual clutch transmission may be used.

  The engine 1 is equipped with an engine starting and power generation device 6, and the engine starting and power generation device 6 is provided with a motor generator (not shown). In the engine start, the engine start and power generation device 6 drives the motor generator using the power supplied from the in-vehicle battery 7 based on the engine start command, and performs engine cranking. Further, when the fuel is injected and then the engine 1 is rotated independently, the motor generator is stopped. In power generation, the engine starting and power generation device 6 generates power when the motor generator is rotationally driven by the engine 1, and supplies the generated power to the in-vehicle battery 7.

  Although omitted in the present embodiment, when the engine restart is performed by the motor generator, for example, a DC / DC converter may be used as a measure against the instantaneous power failure due to the voltage drop due to the driving power of the motor generator.

  The torque converter 2 amplifies the torque at low vehicle speeds and has a lock-up clutch. When the vehicle speed exceeds a predetermined vehicle speed, the torque converter 2 engages the lock-up clutch and inputs the output shaft of the engine 1 and the belt type continuously variable transmission 4. Regulates relative rotation with the shaft.

  The belt-type continuously variable transmission 4 includes a start clutch 3, a primary pulley and a secondary pulley, and a belt stretched over these pulleys, and achieves a desired gear ratio by changing the pulley groove width by hydraulic pressure. . An oil pump 8 driven by the engine 1 is provided inside the belt-type continuously variable transmission 4, and the oil pump 8 is used as a hydraulic source to supply the converter pressure and lockup pressure of the torque converter 2, and the belt The pulley continuously variable transmission 4 and the clutch engagement pressure are supplied.

  Further, the belt-type continuously variable transmission 4 is provided with an electric oil pump 9, and when the oil pump 8 cannot supply hydraulic pressure due to the automatic engine stop, the electric oil pump 9 is operated and the necessary oil pressure is set. The actuator can be supplied. Therefore, even when the engine is stopped, the hydraulic oil leakage can be compensated and the clutch engagement pressure can be maintained.

  The operating state of the engine 1 is controlled by an engine control unit (hereinafter referred to as ECU) 10. The ECU 10 includes, for example, a brake signal from a brake switch 11 that outputs an ON signal when a driver operates a brake pedal, and a brake operation from a brake operation amount sensor 12 that detects a brake pedal stroke amount and a driver's brake pedal depression force. An amount signal, an accelerator signal from an accelerator pedal opening sensor 13 for detecting the amount of accelerator pedal operation by the driver, a wheel speed from a wheel speed sensor 14 provided for each wheel, and an outside air temperature sensor for detecting outside air temperature. 15, an outside air temperature signal, a transmission state signal related to the engine operating state such as a transmission ratio from a transmission control unit (TCU) 16, which will be described later, a shift state signal from the shift state switch 17, and a longitudinal direction applied to the vehicle Deceleration signal from acceleration sensor 18 for detecting acceleration And an angular velocity signal from the yaw rate sensor 19, a terrain and traffic information signal from the navigation system 20, an inter-vehicle distance signal from the inter-vehicle distance measuring device 21, and signals such as engine water temperature, crank angle, and engine speed. To do.

  The transmission control unit (TCU) 16 transmits / receives signals of the engine operating state and the transmission state to / from the ECU 10 and controls the gear ratio of the belt type continuously variable transmission 4 based on these signals. Specifically, when the travel range is selected, the start clutch 3 is engaged, and the gear ratio is determined from the gear ratio map based on the accelerator pedal opening and the vehicle speed, and each pulley pressure is controlled. Further, when the vehicle speed is lower than the predetermined vehicle speed, the lockup clutch is released, and when the vehicle speed is higher than the predetermined vehicle speed, the lockup clutch is engaged, and the engine 1 and the belt type continuously variable transmission 4 are brought into a direct connection state. Further, when the engine is stopped while the travel range is selected, the electric oil pump 9 is operated to ensure the necessary hydraulic pressure.

  Next, coasting control of engine automatic stop / restart control processing in the vehicle control apparatus configured as described above will be described. The coasting control is basically executed when it is recognized that acceleration is not required due to the driver's accelerator or brake operation.

  During coasting control, the driving source and the vehicle are completely disconnected by opening the starting clutch 3 in the belt-type continuously variable transmission 4 between the engine 1 as a vehicle driving source and the driving wheels 5 of the vehicle. . During the coasting control, the vehicle becomes a simple inertia body except for mechanical loss included between the starting clutch 3 and the drive wheels 5, and is decelerated mainly by a traveling resistance component necessary for traveling. Running in this state is called coasting running.

  Normally, when a braking operation is detected during coasting, the engine 1 is started by a motor generator, and the torque converter 2 applies a shock by combining the engine 1 side rotation speed of the start clutch 3 and the drive wheel 5 side rotation speed. Cancel coasting while absorbing.

The vehicle control apparatus according to the first embodiment performs automatic stop / restart control of the engine 1 while determining whether the vehicle state is stable when a brake operation is detected and it is desired to cancel the coasting state. is there.

The engine automatic stop / restart control process executed by the ECU 10 in the vehicle control apparatus according to the first embodiment will be described below.
FIG. 2 is a flowchart showing an engine automatic stop / restart control process executed by the ECU 10. The following processing is performed when a brake signal is detected during coasting. The engine automatic stop / restart control process shown in FIG. 2 includes steps S101 to S106 from the start to the end.

  First, in step S101, the brake operation amount requested by the driver is detected from the brake operation amount sensor 12 that detects the brake pedal stroke amount and the driver's brake pedal depression force.

  In step S102, the driver's requested deceleration is calculated. For calculating the driver's required deceleration, a relationship map between the brake operation amount and the engine brake operation amount and the required deceleration previously stored in the memory area of the ECU 10 is used. Thus, the driver's requested deceleration is obtained.

  In step S103, the magnitude of the driver's requested deceleration is determined. As a determination, a reference predetermined value of the magnitude of the deceleration applied when the vehicle is suddenly braked is given to the ECU 10 in advance as α, and if the driver's required deceleration is larger than the reference predetermined value α, the process proceeds to step S104 to start the clutch 3 After performing the process of continuing the coasting without connecting, the process returns to step S102 to confirm the driver's requested acceleration again. As a result, it is possible to prevent the vehicle from becoming unstable due to engine restart at the time of sudden braking, improve the braking performance of the vehicle, and smooth the braking. Further, if the driver's requested deceleration is smaller than the reference predetermined value α, the process proceeds to the determination in the next step S105.

  In step S105, it is determined whether or not it responds to the deceleration corresponding to the minute brake operation. The minute brake operation causes the coasting control to be unintended by the driver. By continuing the coasting process until the deceleration γ according to the minute brake operation, it is possible to prevent the unintended coasting start and end due to the brake operation from being repeated. In this step S105, when it is determined that the operation is a minute brake operation, the process proceeds to step S104, the process of continuing the coasting without connecting the starting clutch 3 is performed, and the process returns to step S102 to confirm the driver's requested acceleration again. As a result, it is possible to improve deterioration of fuel consumption due to excessive fuel injection and deterioration of drivability due to unnecessary connection of the start clutch 3.

  If it is determined that the operation is not a minute brake operation, the process proceeds to step S106, the engine 1 is restarted, the coasting control is terminated, and the process is terminated.

  By controlling as described above, the following effects can be obtained. That is, when the deceleration requested by the driver is large (during sudden deceleration), coasting is terminated as usual, and when the engine 1 is restarted and the start clutch 3 is connected, an unexpected driving torque is applied at the time of connection. This can cause the vehicle to become unstable. Also, even when anti-lock brake control that causes the drive wheel 5 to slip is activated due to poor road surface condition, if coasting is released with the brake, an unexpected driving torque is applied when the start clutch 3 is connected, and the vehicle becomes unstable. There is a risk that it will be in a bad state.

  However, in the vehicle control apparatus according to the first embodiment, when it is determined that the deceleration requested by the driver is large, the start clutch 3 is not connected and the coasting is continued. As a result, the braking performance of the vehicle can be improved and the braking can be smoothed. In addition, coasting control can be realized more stably by performing engine stop / restart control based on the road surface friction coefficient and the slip ratio.

  Further, the minute brake operation repeats the start and end of the unintended coasting, which leads to deterioration of fuel consumption due to excessive fuel injection and deterioration of drivability due to unnecessary connection of the start clutch 3.

  However, the vehicle control apparatus according to the first embodiment performs control so that coasting is continued without connecting the start clutch 3 at a deceleration of a predetermined value γ or less. By doing so, it becomes possible to prevent deterioration of fuel consumption and drivability.

  Here, in the first embodiment, the engine is started using the motor generator, but the starter 22 may be used. By starting with the starter 22 in this manner, the belt slip does not occur, so that a robust system can be realized.

  Further, in the first embodiment, the driver's required deceleration is obtained from the map with the brake operation amount. However, when it is necessary to correct the change in the deceleration due to the intervention of the slope, the inter-vehicle automatic control system, etc., The corrected requested deceleration may be used. For example, the correction amount of the deceleration due to the gradient can be obtained from a method of calculating and correcting the angle from the angular velocity detected from the yaw rate sensor 19, a method of reading the topographic information from the navigation system 20 and calculating and correcting the gradient angle. A deceleration corrected by the correction amount may be used. In addition, when an inter-vehicle automatic control system or the like is installed and the correction amount can be calculated from the system, the corrected deceleration may be used. For example, in the inter-vehicle automatic control system, the correction amount may be calculated from the inter-vehicle distance measuring device 21 and corrected. By using the deceleration corrected in this way, it is possible to approach the deceleration required by the driver and smooth the braking.

  Further, it may be determined whether each wheel is slipping and the entire vehicle is not in an unstable state using the road surface friction coefficient and the slip ratio.

  First, the slip ratio is calculated from the wheel speed detected from the wheel speed sensor 14 provided in each wheel and the vehicle speed of the entire vehicle obtained by calculation. At the same time, a road surface friction coefficient is detected from a road surface friction coefficient detection unit 23 provided in the ECU 10.

  In addition, when the road surface friction coefficient is detected by the ABS controller or the like instead of obtaining the road surface friction coefficient detection unit 23, the road surface friction coefficient estimated by these other controllers is not limited to the outside air temperature. Coefficient information may be used.

  Next, using the road surface friction coefficient and the slip ratio, it is determined whether each wheel is slipping and the entire vehicle is in an unstable state. Here, in order to determine whether or not each wheel is slipping, the slip ratio is compared with the target slip ratio β when going straight (see FIG. 3). It is assumed that the wheel is slipping when the calculated slip ratio is larger than the target slip ratio β when going straight. In order to determine whether the entire vehicle is in an unstable state, it is determined whether Δμ / ΔS (μ: friction coefficient, S: slip ratio) is negative. If negative, the entire vehicle is in an unstable state. If the result of the judgment is that each wheel slips during the coasting and the entire vehicle is in an unstable state, the engine 1 is forcibly restarted, and further the coasting is performed so that the vehicle does not become unstable. Continue. As a result, the brake system works properly, improving the braking performance of the vehicle and smoothing the braking. Further, when the result of the determination is that each wheel is not slipping during the coasting and the entire vehicle is in a stable state, the coasting is canceled.

  By controlling in this way, the deceleration required by the driver can be realized even when the road surface condition is poor.

  Although the embodiment of the present invention has been described above, the present invention can be appropriately modified or omitted within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Engine, 2 Torque converter, 3 Starting clutch, 4 Belt type continuously variable transmission, 5 Drive wheel, 6 Engine start-up and power generation device, 7 Car battery, 8 Oil pump, 9 Electric oil pump, 10 Engine control unit (ECU) , 11 brake switch, 12 brake operation amount sensor, 13 accelerator pedal opening sensor, 14 wheel speed sensor, 15 outside air temperature sensor, 16 transmission control unit (TCU), 17 shift state switch, 18 acceleration sensor, 19 yaw rate sensor, 20 Navigation system, 21 inter-vehicle distance measuring device, 22 starter, 23 road surface friction coefficient detector.

The vehicle control apparatus according to the present invention includes a brake operation amount detection unit that detects a driver's brake operation amount, a request deceleration calculation unit that calculates the driver's request deceleration from an output of the brake operation amount detection unit, and Coasting control determination means for determining whether to continue or cancel the coasting according to the required deceleration while the vehicle is traveling on coasting ,
The coasting control determination means continues coasting when the requested deceleration exceeds a first range predetermined according to the vehicle, and the requested deceleration is within the first range. Is determined, whether the requested deceleration is within a second range unintended by the driver, and if it is within the second range, the coasting is continued, and the second range is When it exceeds, the coasting travel is canceled .

The vehicle control apparatus according to the present invention includes a brake operation amount detection unit that detects a driver's brake operation amount, a request deceleration calculation unit that calculates the driver's request deceleration from an output of the brake operation amount detection unit, and Coasting control determination means for determining whether to continue or cancel the coasting according to the required deceleration while the vehicle is traveling on coasting,
The coasting control determination means continues coasting when the requested deceleration exceeds a first range predetermined according to the vehicle, and the requested deceleration is within the first range. Is determined to determine whether the requested deceleration is within a second range not intended to release the driver's coasting control , and if within the second range, the coasting is continued, The coasting travel is canceled when the second range is exceeded.

Claims (4)

Brake operation amount detection means for detecting the brake operation amount of the driver;
Request deceleration calculation means for calculating the driver's request deceleration from the output of the brake operation amount detection means;
Coasting control determination means for determining whether to continue or cancel the coasting according to the requested deceleration while the vehicle is traveling in coasting,
A vehicle control device characterized by comprising:   2. The vehicle control device according to claim 1, wherein the coasting traveling is canceled when the required deceleration is within a range predetermined according to the vehicle. Means for detecting wheel speed on the wheel of the vehicle; means for detecting the vehicle speed of the entire vehicle; means for calculating a slip ratio of the wheel from the wheel speed and the vehicle speed; An anti-lock brake control means maintained at a slip ratio to prevent the wheels from locking,
The vehicle control apparatus according to claim 1 or 2, wherein the coasting is continued when the antilock brake control means operates. A navigation system capable of acquiring terrain and traffic information;
Determining means for reading out the terrain information from the navigation system and determining the continuation of the coasting from the deceleration correction amount obtained by calculating the slope angle and the requested deceleration calculated by the requested deceleration calculating means; The vehicle control device according to claim 1, wherein the vehicle control device is provided.

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