Vehicle control device

Abstract

To enable an engine to automatically re-operate if an engine rotation speed is increased according to release of a brake when a brake limitation device cannot operate and an engine stall is caused due to fuel cut during operation of a brake.SOLUTION: A vehicle control device is structured as follows: at abnormal time when an ABS control device as a brake limitation device cannot operate, even if engine stall occurs because driving wheels are locked by operation of a wheel brake and an engine rotation speed Ne is reduced, and the determination of step S1 becomes YES and protection F / C (fuel cut) is executed in step S2, fuel supply is restarted and thereby an engine is automatically re-operated and a driving operation is facilitated because the determination of step S5 becomes YES and the protection F / C is stopped in step S6 when the engine rotation speed Ne becomes a fuel cut stop determination value (nereso+α) or more according to release of a brake.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device, and more particularly to a technique for cutting fuel when there is a risk of resonance occurring in a power transmission device. [Background technology]

[0002] Vehicles having an engine that generates power by burning fuel and a power transmission device provided between the engine and drive wheels are widely known. Patent Document 1 discloses an example of such a vehicle, which discloses that resonance may occur in the low engine speed range (see paragraph 0008 and FIG. 8). Patent Document 2, on the other hand, describes a technology that, when resonance may occur in the power transmission device, cuts off fuel supply to the engine, forcibly stalls the engine, and thereby suppresses damage to the power transmission device and engine, reduction in durability, and the like due to resonance (see paragraph 0037). In this case, when a predetermined restoration condition is met, such as when a starter switch for starting the engine is turned on, the fuel cut is stopped, fuel supply is resumed, and the engine is restarted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2014-222025 [Patent Document 2] Japanese Patent Application Publication No. 2020-159229 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle equipped with a brake limiting device, such as an antilock brake system (ABS) or vehicle stability control (VSC), that limits the braking torque applied to the wheel brakes of the drive wheels to prevent the drive wheels from locking, if the brake limiting device malfunctions or malfunctions, the drive wheels are more likely to lock when the wheel brakes are activated, causing a drop in engine speed. In this case, if the engine speed drops and enters a resonant speed range, a fuel cut is implemented to prevent resonance, causing the engine to stall. If the wheel brakes are released while the vehicle is moving, the drive wheels rotate again, causing the engine speed to rise above the resonant speed range, but the fuel cut remains and the engine does not restart. The engine can be restarted by canceling the fuel cut by turning on the starter switch or other means to satisfy the recovery requirements, but this is a cumbersome operation.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to enable the engine to automatically restart when the engine speed increases as the brake is released, in a case where the brake limiting device is inoperable and engine stall is likely to occur due to fuel cut when the brake is applied. [Means for solving the problem]

[0006] In order to achieve this object, the first invention relates to a vehicle control device (a) having an engine that generates power by burning fuel and a power transmission device arranged between the engine and drive wheels, (b) having a fuel cut control unit that performs a fuel cut to stop the supply of fuel to the engine when there is a risk of resonance occurring in the power transmission device and cancels the fuel cut when predetermined resumption requirements are met, (c) the vehicle is equipped with a brake limiting device that limits the braking torque applied to the wheel brakes arranged on the drive wheels so as to prevent the drive wheels from locking, and (d) when the brake limiting device is inoperable, the fuel cut control unit cancels the fuel cut when the engine speed, which is the engine speed, reaches or exceeds a predetermined fuel cut cancellation judgment value, even if the resumption requirements are not met.

[0007] The second invention is characterized in that, in the vehicle control device of the first invention, (a) the recovery requirements include a case where a starter switch for starting the engine is turned ON, and (b) when the brake limiting device is inoperable, the fuel cut control unit stops the fuel cut when the engine rotation speed becomes equal to or greater than the fuel cut stop judgment value, even if the starter switch is not turned ON.

[0008] A third invention is characterized in that, in the vehicle control device of the first or second invention, (a) the fuel cut control unit implements the fuel cut when predetermined fuel cut execution conditions are met, including the engine speed being within a predetermined resonance speed range, while (b) the fuel cut cancellation judgment value is set to a speed higher than the resonance speed range.

[0009] A fourth aspect of the present invention is characterized in that, in the vehicle control device of the third aspect of the present invention, (a) the resonance rotation speed region is set to a region equal to or lower than the idle rotation speed of the engine, and (b) the fuel cut termination judgment value is set to a rotation speed equal to or higher than the idle rotation speed.

[0010] A fifth invention is characterized in that, in the vehicle control device of the fourth invention, (a) the vehicle is a manually-shifted vehicle that has, as the power transmission device, a flywheel damper, a clutch device that connects and disconnects the power transmission path, and a manual transmission that is operated by the driver, arranged in series from the engine side, and (b) the resonance rotation speed range of the fuel cut execution condition is a rotation speed range in which resonance may occur in the flywheel damper. [Effects of the Invention]

[0011] In such a vehicle control device, if the brake limiting device is inoperable, the drive wheels lock when the wheel brake is activated, causing the engine speed to drop, and fuel cutoff to suppress resonance is performed, resulting in an engine stall. However, if the engine speed reaches or exceeds the fuel cutoff stop determination value upon brake release, the fuel cutoff is stopped, and fuel supply is resumed, automatically restarting the engine and facilitating driving operation. Furthermore, since the fuel cutoff is stopped and the engine is restarted when the engine speed increases, provided that the brake limiting device is inoperable, there is no risk of fuel cutoff being stopped more than necessary, and driving operation can be improved by focusing on engine stalls caused by the inoperability of the brake limiting device.

[0012] In the second invention, the requirement for recovery is that the starter switch must be turned ON. However, if the brake limiting device is inoperable, the fuel cut will be stopped when the engine speed reaches or exceeds the fuel cut stop judgment value even if the starter switch is not turned ON. This eliminates the need to turn the starter switch ON each time the engine is restarted, making driving easier.

[0013] In the third invention, the fuel cut execution conditions are defined to include the engine speed being within a predetermined resonance speed range, while a speed higher than that resonance speed range is defined as the fuel cut cancellation judgment value.When the engine speed reaches or exceeds the fuel cut cancellation judgment value, the fuel cut is canceled, fuel supply is resumed, and the engine is restarted, so that the engine can be automatically restarted while appropriately suppressing resonance in the power transmission device.

[0014] In the fourth aspect of the present invention, since the resonance rotation speed range is set to a range below the idle rotation speed of the engine, if the drive wheels lock and the engine rotation speed drops when the wheel brake is activated while the brake limiting device is inoperable, fuel cutoff is performed to suppress resonance, which may result in engine stall, but the fuel cutoff cancellation judgment value is a rotation speed above the idle rotation speed. Therefore, the advantageous effect of the present invention is appropriately achieved, which is to appropriately suppress the occurrence of resonance due to the drive wheels locking when the brake limiting device is inoperable, while facilitating driving by canceling fuel cutoff and automatically restarting the engine when the engine rotation speed rises due to the wheel brake being released.

[0015] The fifth invention relates to a manually-shifted vehicle equipped with a flywheel damper, a clutch device, and a manual transmission as a power transmission device. The flywheel damper, which has a large mass, may resonate in a predetermined resonant speed range below idle speed. Furthermore, in a manually-shifted vehicle, the clutch device is kept engaged while the vehicle is running, and the engine rotates according to the rotational speed of the drive wheels. Therefore, if the drive wheels are locked by the activation of the wheel brakes, the engine speed may drop and enter the resonant speed range. In other words, if the brake limiting device is inoperable and the drive wheels are locked when the wheel brakes are activated, and the engine speed drops below idle speed, a fuel cutoff is implemented to suppress resonance, which may result in an engine stall. Therefore, by canceling the fuel cutoff and automatically restarting the engine when the engine speed increases due to the brake release, the vehicle can appropriately achieve the effect of facilitating driving. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of a vehicle drive system equipped with an electronic control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of the clutch device of FIG. [Figure 3] 2 is a flowchart illustrating ON / OFF switching of a protective fuel cut request, which is executed by an fuel cut control unit that the electronic control device of FIG. 1 functionally comprises. [Figure 4] 4 is an example of a time chart illustrating changes in the operating state of each part when a protective fuel cut request is switched between ON and OFF according to the flowchart of FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention is applicable to a manually-shifted vehicle having, for example, a flywheel damper, a clutch device, and a manual transmission as a power transmission device, but is equally applicable to vehicles in which the engine rotates in accordance with the rotation speed of the drive wheels while the vehicle is running, and the engine speed is reduced when the drive wheels lock. For example, the present invention may also be applied to an automatically-shifted vehicle having an automatic transmission. The clutch device is configured to mechanically connect and disconnect the power transmission path in response to, for example, a driver's operation to disconnect the power transmission path, but it may also be configured to electrically connect and disconnect the power transmission path, or an automatic clutch that automatically disconnects the power transmission path when the manual transmission is shifted can also be used. The manual transmission is configured to mechanically change gears in response to, for example, a driver's operation to change gears, but it may also be configured to electrically change gears.

[0018] The fuel cut control unit is configured to perform fuel cut to suppress resonance of a flywheel damper, for example, but the present invention can also be applied to suppressing resonance of rotating members other than the flywheel damper, such as a manual transmission, a drive shaft, etc. A recovery requirement for halting fuel cut is, for example, when a starter switch for starting the engine is turned ON, but other operations such as accelerator operation or clutch operation, or a specified vehicle state, etc. may also be defined as a recovery requirement. [Example]

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings have been appropriately simplified or modified for the purpose of explanation, and the shapes, dimensional ratios, angles, etc. of the various parts are not necessarily drawn accurately.

[0020] FIG. 1 is a schematic diagram illustrating the drive system of a vehicle 10 equipped with an electronic control device 80 as a control device according to one embodiment of the present invention, for a front-engine, rear-wheel-drive (FR) vehicle. The vehicle 10 includes an engine 12 used as a power source for driving the vehicle, and a power transmission device 16 disposed between the engine 12 and drive wheels 14. The engine 12 is an internal combustion engine that generates power by burning fuel, such as a gasoline or diesel engine, and includes an electronic throttle valve controlled according to the accelerator opening θacc, a fuel injection device, an ignition device, and the like. The power transmission device 16 includes a flywheel damper 18, a clutch device 20, and a manual transmission 22 in series from the engine 12 side, and the vehicle 10 is a manually-shifted vehicle.

[0021] The flywheel damper 18 is attached to a crankshaft 24 of the engine 12. The clutch device 20 is operated to engage or disengage the clutch by the driver, and is, for example, a dry single-plate friction clutch as shown in FIG. 2. The clutch device 20 is configured to include a clutch disc 28 attached to a clutch output shaft 26, a pressure plate 32 disposed in a clutch housing 30, a diaphragm spring 34 that presses the clutch disc 28 and transmits power by urging the pressure plate 32 toward the flywheel damper 18, and a release sleeve 42 that displaces the inner end of the diaphragm spring 34 leftward in the figure to interrupt (release) the power transmission. When the clutch pedal 36 is depressed, the release sleeve 42 is moved leftward in the figure via a release fork 40, displacing the inner end of the diaphragm spring 34 leftward. The clutch pedal 36 is depressed by the driver to disengage the clutch device 20, and the clutch pedal 36 and release fork 40 are mechanically connected via a mechanical interlocking device 38 such as a link or a push-pull cable. In this embodiment, the flywheel damper 18 forms part of the clutch device 20, and the clutch housing 30 is fixed to the flywheel damper 18. It is also possible to configure the flywheel damper 18 and the clutch device 20 separately.

[0022] The manual transmission 22 is a stepped transmission, such as a two-shaft mesh type, that can establish multiple gears with different gear ratios, and is operated by the driver to change gears. That is, the driver operates a shift lever (not shown) to mechanically or electrically switch to one of the multiple gears. Power output from the manual transmission 22 is transmitted from a propeller shaft 44 to a differential 46 and distributed to the left and right drive wheels 14 via a pair of drive shafts 48.

[0023] The vehicle 10 is equipped with an electronic control unit 80 as a control device that executes various types of control. The electronic control unit 80 includes a so-called microcomputer, and performs signal processing according to a program pre-stored in a ROM while utilizing the temporary storage function of a RAM. The electronic control unit 80 functionally includes an engine control unit 82 and an F / C control unit 84.

[0024] The electronic control unit 80 receives signals representing various information necessary for various controls, such as engine speed Ne, input speed Ni, output speed No, accelerator pedal position θacc, clutch disengagement state Con, starter operation state Sstart, brake ON state Bon, and ABS operation state Sabs, from, for example, the engine speed sensor 50, input speed sensor 52, output speed sensor 54, accelerator pedal position sensor 56, clutch switch 58, starter switch 60, brake switch 62, and ABS control unit 70. The engine speed Ne is the speed of the engine 12. The input speed Ni is the rotational speed of the clutch output shaft 26, etc., and is the input rotational speed of the manual transmission 22. The output speed No is the rotational speed of the propeller shaft 44, etc., and is the output rotational speed of the manual transmission 22, and corresponds to the vehicle speed V. The accelerator pedal position θacc is the amount of driving required by the driver, such as the amount of operation of the accelerator pedal. The clutch disengagement state Con is output from the clutch switch 58 when the clutch pedal 36 is depressed, and indicates that the clutch device 20 is in a disengaged state. The starter operation state Sstart indicates the operation state of the starter switch 60, and includes an ON operation that starts the engine 12 and enables the vehicle 10 to run, an ACC operation that enables operation of only the accessories, and an OFF operation that stops all operation of the vehicle 10. The starter switch 60 is, for example, an automatic reset push button switch, but it may also be a rotary switch that is held in the ACC position after the engine is started by an ON operation.

[0025] The brake ON state Bon is output from the brake switch 62 when the brake pedal 72 is depressed, and indicates a brake operating state in which brake oil pressure is supplied from the wheel brake device 74 via the brake piping 76 to the wheel brakes 78 arranged on all of the wheels of the vehicle 10, including the drive wheels 14, and brake torque is applied. The wheel brake device 74 is equipped with a brake booster, a master cylinder, etc., and outputs brake oil pressure generated from the master cylinder in response to the force with which the driver depresses the brake pedal 72 to, for example, multiple wheel brakes 78 via multiple systems.

[0026] The ABS control device 70, which functions as a brake limiting device, performs ABS control by limiting the braking torque applied to wheel brakes 78 to prevent all wheels of the vehicle 10, including the drive wheels 14, from locking, i.e., preventing the wheels from slipping and stopping, regardless of the depression of the brake pedal 72. The ABS control device 70 receives information about the rotational speed of each wheel from wheel speed sensors installed on all wheels. Based on the wheel speed, the ABS control device 70 determines whether wheel locking is likely to occur. If it determines that wheel locking is likely to occur, the ABS control device 70 controls the wheel brake devices 74 to reduce the brake hydraulic pressure output to the wheel brakes 78. The ABS control device 70 also has an abnormality detection function that determines whether an abnormality exists, such as a current interruption due to a broken wire or a change in the wheel rotational speed in response to a hydraulic pressure command signal, preventing the wheel brake devices 74 from being properly controlled to prevent wheel locking. If an abnormality is detected, the ABS control device 70 halts ABS control. The signal indicating the ABS operation status Sabs, supplied from the ABS control device 70 to the electronic control device 80, includes information indicating whether the ABS is operating, reducing the brake hydraulic pressure, and also information indicating whether an abnormality exists, halting ABS control.

[0027] An engine control section 82 functionally provided in the electronic control device 80 calculates a required drive torque Trdem [Nm] at the drive wheels 14 based on, for example, the accelerator opening θacc, which are the required drive amounts, and vehicle speed V, and determines a target engine torque Tet that can realize the required drive torque Trdem.Then, an engine control signal Se is output that controls the engine 12 so that the target engine torque Tet is output, and controls the throttle opening of the electronic throttle valve, the fuel injection amount of the fuel injection device, the ignition timing of the ignition device, etc.

[0028] The fuel cut control unit 84 corresponds to a fuel cut control unit, and when there is a risk of resonance occurring in the flywheel damper 18, it performs a fuel cut to stop the fuel supply to the engine 12 from the fuel injection device. This fuel cut is performed in priority to the fuel injection control by the engine control unit 82. Because the flywheel damper 18 has a large mass, resonance may occur in a predetermined resonant rotation speed range below the idle rotation speed of the engine 12. In this embodiment, the range below the resonant rotation speed nereso (see FIG. 4), which is lower than the idle rotation speed, is defined as the resonant rotation speed range, and the predetermined condition for executing the fuel cut is that the engine rotation speed Ne is equal to or less than the resonant rotation speed nereso. The condition for executing the fuel cut may be simply that the engine rotation speed Ne is equal to or less than the resonant rotation speed nereso, or it may be that the state below the resonant rotation speed nereso continues for a predetermined period of time or more. When the engine stalls due to this fuel cut and the autonomous rotation of the engine 12 stops, resonance of the flywheel damper 18 is suppressed, preventing damage to or a decrease in durability of the engine 12, the flywheel damper 18, or surrounding rotating members. In other words, the fuel cut (F / C) in this embodiment is for protecting the flywheel damper 18, and is also referred to as a protective F / C in the following description.

[0029] On the other hand, if predetermined restoration requirements are met, the protective fuel cut is stopped and fuel supply by the fuel injection device is resumed, thereby restarting the engine 12. In this embodiment, the restoration requirement is set to be the ON operation of the starter switch 60. For example, when the vehicle 10 is stopped and the clutch pedal 36 is depressed to interrupt the power transmission path by the clutch device 20, if the starter switch 60 is turned ON, the engine 12 is cranked by a starter motor (not shown) and fuel supply is resumed, thereby restarting the engine 12.

[0030] When the ABS control device 70 malfunctions and ABS control is suspended, the wheel brakes 78 tend to lock the drive wheels 14 when the brake pedal 72 is depressed, for example, on a low-μ road. If the driver does not depress the clutch pedal 36 with the intention of continuing to drive the vehicle 10 and the clutch device 20 remains engaged, the engine speed Ne decreases as the rotational speed of the drive wheels 14 decreases. When the engine speed Ne falls below the resonant speed nereso, a protective fuel cut (F / C) is activated to suppress resonance, causing the engine 12 to stall. While this engine stall protects the flywheel damper 18 from resonance, even if the wheel brakes 78 are released by releasing the brake pedal 72 while the vehicle is moving, and the engine speed Ne increases and exceeds the resonant speed nereso, the protective fuel cut remains in place and the engine 12 does not restart. Therefore, the driver must turn on the starter switch 60 while the vehicle is moving to disable the protective fuel cut, which is cumbersome.

[0031] In contrast, the F / C control unit 84 of this embodiment executes signal processing according to the flowchart of Figure 3, thereby suppressing resonance of the flywheel damper 18 by the protective fuel cut, and when braking by the wheel brakes 78 is released during driving and the engine speed Ne increases, quickly restarting the engine 12 without the need to turn on the starter switch 60. In the flowchart of Figure 3, YES in the decision steps indicated by diamonds means affirmative, and NO means negative.

[0032] In step S1 of FIG. 3, a resonance determination is made for the flywheel damper 18, i.e., a determination is made as to whether the engine speed Ne is within a resonant frequency range equal to or lower than the resonant frequency nereso, thereby satisfying a fuel cutoff execution condition. If the engine speed Ne is higher than the resonant frequency nereso and outside the resonant frequency range, step S3 is immediately executed without executing step S2. However, if the engine speed Ne is within the resonant frequency range, step S2 is executed. In step S2, a protective fuel cut execution request to protect the flywheel damper 18 is turned ON, and then step S3 is executed. For example, if the wheel brakes 78 lock the drive wheels 14 during an ABS abnormality, and the engine speed Ne decreases as the drive wheels 14 rotate, resulting in a YES determination in step S1, the protective fuel cut execution request is turned ON in step S2. If the protective fuel cut execution request is turned ON in step S2, the protective fuel cut is executed in accordance with the execution request.

[0033] In step S3, it is determined whether the starter switch 60 has been turned ON. If the starter switch 60 has been turned ON, step S6 is executed. In step S6, a protective fuel cut request for protecting the flywheel damper 18 is turned OFF. This turning OFF of the protective fuel cut request stops the protective fuel cut, and fuel injection control by the engine control unit 82 is resumed. If the determination in step S3 is NO, step S4 is executed to determine whether there is an ABS abnormality, i.e., whether there is an abnormality in the ABS control device 70. If there is no ABS abnormality, the process ends and steps S1 and subsequent steps are repeated. If there is an ABS abnormality, step S5 is executed. In step S5, it is determined whether the engine speed Ne is equal to or greater than a fuel cut stop determination value (nereso+α), which is calculated by adding a predetermined safety value α to the resonance speed nereso. If Ne<(nereso+α), the process ends and steps S1 and subsequent steps are repeated. If Ne≧(nereso+α), step S6 is executed to turn OFF the protective fuel cut request. The safety value α is a value that reliably prevents resonance, and is determined so that the fuel cut termination determination value (nereso+α) is equal to or greater than the idle speed.

[0034] When the protective fuel cut request is turned OFF in step S6 and fuel injection control by the engine control unit 82 is resumed, for example, if step S6 is executed following step S3 while the vehicle 10 is stopped, the starter switch 60 is turned ON to crank the engine 12 by the starter motor and restart the fuel supply, thereby restarting the engine 12. Also, if the drive wheels 14 are locked by the wheel brakes 78 during an ABS abnormality, and the engine speed Ne decreases as the rotation of the drive wheels 14 decreases, the determination in step S1 is YES, the protective fuel cut request is turned ON in step S2, the protective fuel cut is executed, and the engine 12 stalls. In this case, if the brake pedal 72 is released while traveling to release the wheel brakes 78, the rotation of the drive wheels 14 resumes, the engine speed Ne increases, and the determination in step S5 is YES, the engine 12 is restarted as the fuel supply by the engine control unit 82 resumes, and the engine 12 is quickly restarted.

[0035] FIG. 4 is an example of a time chart illustrating changes in the operating state of each component when the protective F / C implementation request for the flywheel damper 18 is switched ON and OFF according to the flowchart of FIG. 3. More specifically, this illustrates a situation in which the vehicle is traveling on a low μ road or the like with the accelerator pedal OFF (θacc = 0) during an ABS abnormality. In the "Clutch Switch" column of FIG. 4, ON means that the clutch pedal 36 is depressed and the clutch device 20 is disengaged, while OFF means that the clutch pedal 36 is released and the clutch device 20 is engaged. In other words, FIG. 4 illustrates a situation in which the clutch pedal 36 is released and the clutch device 20 remains engaged. In the "Brake Switch" column, ON means that the brake pedal 72 is depressed and the wheel brake 78 is engaged (brake ON state Bon), while OFF means that the brake pedal 72 is released and the wheel brake 78 is not engaged.

[0036] Time t1 in Figure 4 is the time when depression of the brake pedal 72 begins, and the vehicle speed V decreases due to the brake torque of the wheel brake 78, and the engine speed Ne also decreases. Time t2 is the time when the drive wheels 14 lock due to the brake torque of the wheel brake 78 due to an ABS abnormality, and the engine speed Ne starts to decrease rapidly. Time t3 is the time when the engine speed Ne decreases to below the resonance speed nereso, the determination in step S1 becomes YES, the protective fuel cut request is turned ON in step S2, and the protective fuel cut is started in accordance with the protective fuel cut request being ON, and the engine 12 stalls.

[0037] Subsequently, at time t4, the brake pedal 72 is released and the wheel brakes 78 are deactivated. This unlocks the drive wheels 14, allowing them to rotate according to the vehicle speed V. As the drive wheels 14 begin to rotate, the engine speed Ne begins to increase. At time t5, the engine speed Ne becomes higher than the resonance speed nereso, and the determination in step S1 is NO, i.e., the resonance determination of the flywheel damper 18 is OFF. At this time, the engine speed Ne is lower than the fuel cutoff termination determination value (nereso+α), so the determination in step S5 is NO, the protective fuel cut implementation request remains ON, and fuel cut continues. At time t6, the engine speed Ne becomes equal to or higher than the fuel cutoff termination determination value (nereso+α), the determination in step S5 is YES, step S6 is executed, and the protective fuel cut implementation request is turned OFF. As a result, the protective fuel cut is stopped, fuel injection control by the engine control unit 82 is resumed, and the engine 12 is quickly restarted as fuel is supplied.

[0038] In this way, in the F / C control section 84 that is functionally provided in the electronic control device 80 of the vehicle 10 of this embodiment, when an abnormality occurs in which the ABS control device 70, which is a brake limiting device, is inoperable, braking by the wheel brakes 78 locks the drive wheels 14 and the engine speed Ne decreases, and the judgment in step S1 becomes YES and a protective F / C is executed in step S2, causing the engine to stall.However, when the engine speed Ne becomes equal to or greater than the fuel cut cancellation judgment value (nereso+α) as the brakes are released, the judgment in step S5 becomes YES and the protective F / C is canceled in step S6, so that the engine is automatically restarted by resuming fuel supply, making driving easier.

[0039] Furthermore, provided that the ABS control device 70 is abnormal, the protective fuel cut is stopped and the engine 12 is restarted when the engine speed Ne increases, so there is no risk of the protective fuel cut being stopped more than necessary, and driving operability can be improved by focusing on engine stalls caused by abnormalities in the ABS control device 70.

[0040] Furthermore, while turning on the starter switch 60 is specified as a requirement for recovery, in the event of an abnormality that makes the ABS control device 70 inoperable, even if the starter switch 60 is not turned on, the protective F / C will be canceled when the engine speed Ne reaches or exceeds the fuel cut cancellation judgment value (nereso+α). This eliminates the need to turn on the starter switch 60 each time to restart the engine 12, making driving easier.

[0041] In addition, the condition for executing fuel cut is set to be that the engine speed Ne is within a resonant speed range equal to or lower than the resonant speed nereso (step S1), while the fuel cut termination judgment value is set to be a speed (nereso+α) that is higher than the resonant speed nereso by a safety value α (step S5). When the engine speed Ne becomes equal to or higher than the fuel cut termination judgment value (nereso+α), the protective F / C is terminated, fuel supply is resumed, and the engine 12 is restarted. Therefore, the engine 12 can be automatically restarted while appropriately suppressing the resonance of the flywheel damper 18.

[0042] Furthermore, because the resonance speed range below the resonance speed nereso is set to a range below the idle speed of the engine 12, if the ABS control device 70 malfunctions and the drive wheels 14 lock during braking by the wheel brakes 78, causing the engine speed Ne to drop, a protective fuel cut may be implemented, potentially resulting in an engine stall. However, the fuel cut cancellation determination value (nereso+α) is a speed above the idle speed. Therefore, the following advantageous effects are appropriately achieved: the occurrence of resonance due to a drop in engine speed Ne caused by the drive wheels 14 locking during an ABS malfunction is appropriately suppressed; and the protective fuel cut is automatically cancelled and the engine 12 is automatically restarted when the engine speed Ne rises following the release of the wheel brakes 78, thereby facilitating driving.

[0043] This embodiment relates to a manually-shifted vehicle including a flywheel damper 18, a clutch device 20, and a manual transmission 22 as the power transmission device 16. The resonant rotational speed range in which the flywheel damper 18, which has a large mass, may resonate is equal to or lower than the resonant rotational speed nereso, which is lower than the idle rotational speed. Furthermore, when a manually-shifted vehicle is traveling, the clutch device 20 is kept engaged and the engine 12 is rotated according to the rotational speed of the drive wheels 14. Therefore, if the drive wheels 14 are locked by the activation of the wheel brakes 78, the engine rotational speed Ne may drop below the resonant rotational speed nereso. That is, if an abnormality in the ABS control device 70 causes the drive wheels 14 to lock when the wheel brakes 78 are activated, and the engine rotational speed Ne drops below the idle rotational speed, a protective fuel cut may be implemented, potentially resulting in an engine stall. Therefore, by canceling the fuel cut and automatically restarting the engine 12 when the engine rotational speed Ne increases due to the release of the wheel brakes 78, the advantageous effect of facilitating driving is appropriately achieved.

[0044] Although the embodiments of the present invention have been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0045] 10: Vehicle 12: Engine 14: Drive wheels 16: Power transmission device 18: Flywheel damper 20: Clutch device 22: Manual transmission 60: Starter switch 70: ABS control device (brake limiting device) 78: Wheel brake 80: Electronic control device (control device) 84: F / C control unit (fuel cut control unit) Ne: Engine speed nereso: Resonance speed (resonance speed range) nereso+α: Fuel cut cancellation judgment value

Claims

1. A vehicle having an engine that generates power by burning fuel, and a power transmission device provided between the engine and drive wheels, A control device for a vehicle including a fuel cut control unit that cuts off fuel supply to the engine when there is a risk of resonance occurring in the power transmission device, and that stops the fuel cut when predetermined recovery requirements are met, the vehicle is provided with a brake limiting device that limits a brake torque applied to a wheel brake disposed on the drive wheel so as to prevent the drive wheel from locking; When the brake limiting device is inoperable, the fuel cut control unit stops the fuel cut when the engine speed, which is the rotation speed of the engine, becomes equal to or greater than a predetermined fuel cut stop determination value, even if the restoration requirement is not satisfied. A vehicle control device characterized by:

2. The recovery requirement includes a case where a starter switch for starting the engine is turned on, When the brake limiting device is inoperable, the fuel cut control unit stops the fuel cut when the engine rotation speed becomes equal to or greater than the fuel cut stop determination value even if the starter switch is not turned on.

2. The vehicle control device according to claim 1.

3. The fuel cut control unit performs the fuel cut when a predetermined fuel cut execution condition is satisfied, which includes the engine speed being within a predetermined resonance speed region, and The fuel cut stop determination value is set to a rotation speed higher than the resonance rotation speed region.

3. The vehicle control device according to claim 1 or 2.

4. the resonance rotation speed region is set to a region equal to or lower than an idle rotation speed of the engine, The fuel cut stop determination value is set to a rotation speed equal to or greater than the idle rotation speed.

4. The vehicle control device according to claim 3.

5. The vehicle is a manual transmission vehicle including, as the power transmission device, a flywheel damper, a clutch device that connects and disconnects a power transmission path, and a manual transmission that is operated by a driver to change gears, arranged in series from the engine side, The resonant rotation speed range of the fuel cut execution condition is a rotation speed range in which resonance may occur in the flywheel damper.

5. The vehicle control device according to claim 4.

Images