JP2014214690A - Control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an opportunity of an idle stop in an idle stop vehicle.SOLUTION: In a vehicle which performs an idle stop for stopping the idle rotation of an internal combustion engine when idle stop conditions are satisfied, it is included in one of the idle stop conditions that an operation amount of a brake by a driver exceeds a determination threshold, the determination threshold is made variable according to a deceleration degree of the vehicle, and the determination threshold in the case that the deceleration degree is relatively high is set lower than the determination threshold in the case that the deceleration degree is relatively low.

Description

  The present invention relates to a control device for an idle stop vehicle.

  It is known to perform an idle stop that stops the idle rotation of the internal combustion engine while the vehicle is stopped due to a signal or the like (for example, refer to the following patent document). In the existing idling stop system, when the vehicle speed is below a predetermined value, the brake pedal is depressed above a threshold value, and the conditions such as the cooling water temperature of the internal combustion engine and the voltage of the vehicle battery are sufficiently high, the internal combustion engine Stop the engine. During the idling stop, when there is a restart request such as when the driver removes his foot from the brake pedal or depresses the accelerator pedal, the internal combustion engine is restarted.

  Recently, in order to further improve the fuel consumption performance of the vehicle, the vehicle speed condition, which is one of the idle stop conditions, is increased and the idle stop is started before the vehicle stops. This is intended to extend the idle rotation stop period of the internal combustion engine as much as possible.

  In the process where the driver depresses the brake pedal while the vehicle is running and the vehicle is braked to stop, the driver may perform an operation of loosening the depressing of the brake pedal once depressed. In particular, in vehicles equipped with an automatic transmission, the reduction ratio of the automatic transmission increases (ie, shifts to low gear) as the vehicle speed decreases, and the deceleration of the vehicle increases. Try to alleviate. As a result, when the vehicle speed drops to a predetermined value, the amount of depression of the brake pedal has decreased below the threshold value, and the idle stop condition may not be satisfied and the idle stop may not be started.

JP 2012-137018 A

  An object of the present invention is to increase the chance of idle stop in an idle stop vehicle.

  In order to solve the above-described problem, the present invention is a vehicle control apparatus that performs idle stop for stopping idle rotation of an internal combustion engine when an idle stop condition is satisfied, and one of the idle stop conditions includes: It is included that the amount of brake operation by the driver exceeds the determination threshold, the determination threshold is made variable according to the deceleration of the vehicle, and the determination threshold when the deceleration is relatively high The vehicle control device is configured to be set lower than the determination threshold value in the case where it is relatively low.

  In addition, it is also preferable to make the determination threshold variable according to the speed of the vehicle, and set the determination threshold when the vehicle speed is relatively low to be lower than the determination threshold when the vehicle speed is relatively high.

  ADVANTAGE OF THE INVENTION According to this invention, the opportunity of the idle stop in an idle stop vehicle can be increased.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The figure which shows the structure of the drive system in the embodiment. The shift diagram of the continuously variable transmission in the same embodiment. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment performs according to a program.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type 4-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  A brake booster 5 is attached to the vehicle of this embodiment. The brake booster 5 introduces intake negative pressure from a portion of the intake passage 3 downstream of the throttle valve 32, more specifically, from the surge tank 33, and uses this negative pressure to boost the pedaling force of the brake pedal. It is widely known in the field. The brake booster 5 has a constant pressure chamber for storing negative pressure and a variable pressure chamber for applying atmospheric pressure, and the constant pressure chamber is connected to the surge tank 33 via the negative pressure line 51. The negative pressure line 51 guides the intake negative pressure downstream of the throttle valve 32 to the constant pressure chamber. A check valve 52 is provided on the negative pressure line 51 to keep the negative pressure in the constant pressure chamber and prevent the positive pressure from being applied to the constant pressure chamber.

  When the brake pedal is not operated by the driver, the constant pressure chamber and the variable pressure chamber communicate with each other, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the constant pressure chamber and the variable pressure chamber are interrupted, and the atmosphere is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes a control pressure that boosts the depression force of the brake pedal. The brake pedal force amplified by the brake booster 5 is converted into hydraulic pressure in the master cylinder 6. The hydraulic fluid pressure output from the master cylinder 6 is transmitted to a brake device (not shown) such as a brake caliper or a wheel cylinder via a hydraulic circuit (not shown), and is used for braking the vehicle by the brake device.

  FIG. 2 shows an example of a drive system provided in the vehicle. This drive system includes a torque converter 7 and automatic transmissions 8 and 9. In the present embodiment, a forward / reverse switching device 8 using a planetary gear mechanism and a belt-type CVT (Continuously Variable Transmission) 9 which is a type of continuously variable transmission are adopted as components of the automatic transmissions 8 and 9. Yes.

  The rotational torque output from the internal combustion engine is input from the crankshaft of the internal combustion engine to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / reverse switching device 8 and rotates the driven shaft 95 through a shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 101. The output gear 101 meshes with the ring gear 102 of the differential device, and rotates the axle 103 and the drive wheels (not shown) via the differential device.

  The torque converter 7 includes a lockup mechanism. The lock-up mechanism is known in this field, and a lock-up clutch 73 that fastens the input side and the output side of the torque converter 7 so as not to rotate relative to each other, and an operation for switching the connection of the lock-up clutch 73. A lock-up solenoid valve (not shown) for controlling the hydraulic pressure (hydraulic pressure) is used as an element. The lockup solenoid valve is a flow rate control valve that receives a control signal l and changes its opening.

  In a vehicle equipped with CVT 9, when the vehicle speed is a predetermined value (for example, 10 km / h) or more, the torque converter 7 is almost always locked up. When the vehicle speed is equal to or lower than the predetermined value, the lockup of the torque converter 7 is released. During lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates together with the torque converter cover 74. The engine torque input to the input side (drive plate) of the torque converter 7 at the time of lock-up is output from the torque converter cover 74 via the lock-up clutch 73 and thus to the forward / reverse switching device 8. Communicated directly to. At the time of lockup, the speed ratio, which is the ratio of the output side rotational speed of the torque converter 7 to the input side rotational speed, is 1.

  In turn, the lock-up clutch 73 is separated from the torque converter cover 74 at the time of non-lock-up. At the time of non-lock-up, the engine torque input to the input side of the torque converter 7 is transmitted from the torque converter cover 74 to the pump impeller 71 and the turbine 72 and is transmitted to the forward / reverse switching device 8. At the time of non-lock-up, the speed ratio of the torque converter 7 becomes smaller or larger than 1 depending on the driving state.

  In the forward / reverse switching device 8, the sun gear 81 communicates with the turbine runner 72, and the ring gear 82 communicates with the drive shaft 94. Between the planetary carrier 83 that supports the planetary gear 831 and the transmission case, a forward brake 84 that is a hydraulic clutch that can be connected and disconnected is interposed. Further, a reverse clutch 85, which is a hydraulic clutch capable of switching connection / disconnection, is also interposed between the planetary carrier 83 and the sun gear 81 (or the output side of the torque converter 7).

  In the D range of the traveling range, the forward brake 84 is engaged and the reverse clutch 85 is disconnected. As a result, the rotation of the output shaft of the torque converter 7 is reversed and decelerated and transmitted to the drive shaft 94 for forward travel. In turn, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disconnected. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the output shaft of the torque converter 7 and the drive shaft 94 are directly connected to perform reverse travel. A solenoid valve (not shown) that controls the hydraulic pressure for driving the forward brake 84 or the reverse clutch 85 to connect / disconnect is a flow rate control valve that receives a control signal m and changes its opening.

  In the N range and P range, which are non-traveling ranges, both the forward brake 84 and the reverse clutch 85 are disconnected.

  The CVT 9 includes a driving pulley 91 and a driven pulley 92, and a belt 93 wound around the pulleys 91 and 92 as elements. The drive pulley 91 is disposed behind the movable sheave 912, a fixed sheave 911 fixed to the drive shaft 94, a movable sheave 912 supported on the drive shaft 91 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 913 is provided, and the gear ratio (reduction ratio) can be changed steplessly by operating the hydraulic servo 913 and displacing the movable sheave 912. The driven pulley 92 is disposed on the back of the movable sheave 922, a fixed sheave 921 fixed to the driven shaft 95, a movable sheave 922 supported on the driven shaft 95 via a roller spline so as to be axially displaceable. A hydraulic servo 923 is provided, and a belt thrust necessary for torque transmission is applied by operating the hydraulic servo 923 and displacing the movable sheave 922.

  A hydraulic pump (hydraulic fluid) supplied to the forward brake 84 or the reverse clutch 85 to operate the travel range, and a hydraulic pump (discharge fluid) supplied to the hydraulic servos 913 and 923 to operate the gear ratio. (Not shown) is a known mechanical type (non-electric type) that operates by receiving torque transmitted from the crankshaft of the internal combustion engine. This hydraulic fluid is common to the fluid used for the torque converter 7.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening degree signal c output from a sensor that detects the amount or the opening degree of the throttle valve 32 as an accelerator opening degree (so-called required load), detects whether the brake pedal is depressed, or detects the depression amount of the brake pedal. Brake switch or pedaling amount signal d output from the sensor, intake air temperature / intake pressure signal e output from a temperature / pressure sensor that detects intake air temperature and intake negative pressure in the intake passage 3 (especially the surge tank 33), A cooling water temperature signal f output from a water temperature sensor for detecting a cooling water temperature indicating the temperature of the internal combustion engine; The cam angle signal g output from the cam angle sensor at a plurality of cam angles of the shaft or the exhaust camshaft, and the master output from the hydraulic pressure sensor that detects the master cylinder pressure that is the pressure of the hydraulic fluid discharged from the master cylinder 6 A cylinder pressure signal h or the like is input.

  From the output interface, an ignition signal i for the igniter 13 of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and switching of connection / disconnection of the lockup clutch 73. An opening degree control signal l is outputted to the lockup solenoid valve, an opening degree control signal m is outputted to the solenoid valve for switching connection / disconnection of the forward brake 84 or the reverse clutch 85, a transmission ratio control signal n is outputted to the CVT 9, etc. .

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. The ECU 0 applies various control signals i, j, k, l, m, and n corresponding to the operation parameters via the output interface.

  FIG. 3 shows a shift diagram when the ECU 0 controls the CVT 9. The shift diagram represents the target input rotation speed (rotation speed of the turbine 72) corresponding to the vehicle speed and the accelerator opening, and defines the transmission ratio of the CVT 9 corresponding to the vehicle speed and the accelerator opening. In FIG. 3, the shift line when the accelerator opening is 100% is drawn with a thick broken line, the shift line when 50% is drawn with a thick solid line, and the shift line when 0% is drawn with a thick chain line. . The gear ratio takes a value between the low gear side limit L and the high gear side limit H that the CVT 9 can implement in hardware. Assuming that the accelerator opening is constant, the reduction ratio value embodied by the CVT 9 increases as the vehicle speed decreases.

  Further, the ECU 0 inputs a control signal o to an electric motor (starter motor or motor generator, not shown) when the internal combustion engine is started (it may be a cold start or a return from an idling stop). Then, cranking is performed by rotating the crankshaft with an electric motor. Cranking ends when the internal combustion engine starts from the first explosion to a continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the coolant temperature, etc. (assuming that the explosion has been completed) To do.

  The ECU 0 of the present embodiment performs a fuel cut that temporarily stops the fuel supply to the cylinder 1 in accordance with the driving situation. In addition, the ECU 0 also performs an idle stop for stopping the idle rotation of the internal combustion engine when the vehicle stops due to a signal waiting or the like.

  FIG. 3 shows a procedure example of processing executed by the ECU 0 when the vehicle decelerates and stops. When a predetermined fuel cut condition is satisfied (step S1), the ECU 0 performs fuel cut that stops fuel injection from the injector 11 and stops spark ignition by the spark plug 12 (step S2). In step S1, it is determined that the fuel cut condition is satisfied, at least when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed.

  Incidentally, even if the fuel cut condition is satisfied, the fuel injection is not immediately stopped. If the fuel supply is cut off suddenly when the engine torque is relatively large, a torque shock that causes the engine speed and the vehicle speed to drop stepwise occurs, causing the passengers including the driver to feel the shock. In order to reduce the torque shock, the fuel injection is stopped only after the elapse of the delay time after the fuel cut condition is satisfied. During this delay time, the ignition timing is retarded and the engine torque is actively reduced.

  When a predetermined fuel cut end condition is satisfied after the start of fuel cut and before an idle stop condition described later is satisfied (step S3), the fuel cut is ended and fuel injection (and ignition) is resumed. (Step S4). In step S3, it is determined that the fuel cut end condition is satisfied, for example, when the amount of depression of the accelerator pedal exceeds a threshold value or the engine speed decreases to the fuel cut return speed.

  In addition, when a predetermined idle stop condition is satisfied (steps S5 and S6), the ECU 0 executes an idle stop that stops the idle rotation of the internal combustion engine (step S7). In steps S5 and S6, the vehicle speed is equal to or lower than a predetermined value (for example, a value of 10 km / h to 13 km / h), the amount of brake operation by the driver exceeds the determination threshold, and the cooling water temperature and the battery voltage are respectively predetermined values. It is determined that the idle stop condition is satisfied when all the conditions such as higher than the above are satisfied. As an index value that suggests the amount of brake operation, the master cylinder pressure is usually used (that is, the measured master cylinder pressure is compared with the judgment threshold), but a sensor that detects the brake pedal depression amount is implemented. If it is determined, the depression amount measured via the sensor may be compared with a determination threshold value as a brake operation amount.

  After the fuel cut is started, if the fuel cut end condition is not satisfied and the idle stop condition is satisfied (step S5), the fuel injection is not resumed and the fuel cut state is continuously shifted to the idle stop. (Step S7).

  After the idle stop condition is satisfied, when the predetermined idle stop end condition is satisfied (step S8), the internal combustion engine is restarted (step S9). In step S8, the driver has released his / her foot from the brake pedal, conversely, the brake pedal has been further depressed (master cylinder pressure has further increased), and the accelerator pedal has been depressed for a predetermined time (for example, It is determined that the idle stop end condition has been satisfied, for example, after 3 minutes).

  Therefore, in the present embodiment, the determination threshold value to be compared with the brake operation amount (master cylinder pressure or brake pedal depression amount), which is one of the idle stop conditions in steps S5 and S6, is set to the steps S5 and S6. It is variable according to the vehicle deceleration and the vehicle speed at the time of execution.

  In the process where the driver depresses the brake pedal while the vehicle is traveling and the vehicle is braked to stop, the driver may loosen the depressed brake pedal. As already described, the reduction ratio of the CVT 9 increases (that is, shifts to low gear) as the vehicle speed decreases. The deceleration of the vehicle during inertia traveling increases as the reduction ratio of CVT 9 increases. Therefore, the driver tries to adjust the magnitude of braking by loosening the depression of the brake pedal. Thereafter, when the vehicle speed falls below 10 km / h, the lock-up of the torque converter 7 is released, the mechanical load of the internal combustion engine viewed from the axle 103 side is reduced, and the deceleration of the vehicle is reduced. Eventually, the driver steps on the brake pedal again, and the vehicle is completely stopped.

  In addition, the deceleration of the vehicle is affected by the road surface condition (gradient resistance, rolling resistance, etc.) where the vehicle is located, and the load on the vehicle. On an uphill road, a rough road surface, or a situation where the load is small, the deceleration of the vehicle increases, and the amount of brake pedal depression by the driver decreases accordingly.

  In the conventional idle stop control, the determination threshold value to be compared with the brake operation amount is constant. Therefore, if the brake pedal is depressed when the vehicle speed drops to 10 km / h to 13 km / h, the condition that the brake operation amount is equal to or greater than the determination threshold value may not be satisfied, and the idling stop may not be started. It was. If the idle stop cannot be started early, the effective idle stop period is shortened, and wasteful fuel consumption is increased, resulting in a disadvantage in fuel efficiency.

  Therefore, in this embodiment, as the current deceleration of the vehicle is higher, the determination threshold value to be compared with the brake operation amount is set lower in steps S5 and S6, so that it becomes easier to enter an idle stop when the vehicle decelerates. I have to.

  When the vehicle deceleration is originally high, the driver does not push the brake pedal too hard. In other words, even if the amount of brake operation is not large, it is assumed that the driver has an intention to stop the vehicle. Therefore, the opportunity for idling stop is ensured by lowering the determination threshold so that the brake operation amount exceeds the determination threshold.

  Conversely, if the amount of brake operation is not large even though the vehicle deceleration is low, it is presumed that the driver has no intention to stop the vehicle. If the driver wants to slowly decelerate the vehicle but does not want to stop it on a downhill road or in a situation where the load is heavy (and therefore the inertia of the vehicle is large), the driver must apply the brake pedal more than a certain amount. Step on, but the vehicle's deceleration will not be significantly higher. Therefore, the determination threshold value is not lowered and the idle stop is not started against the driver's intention.

  The same can be said about the traveling speed of the vehicle. If the vehicle speed is already sufficiently low, it is assumed that the driver has an intention to stop the vehicle even if the amount of brake operation is not large. On the other hand, if the amount of brake operation is not large even though the vehicle speed is still high, it is assumed that the driver has no intention to stop the vehicle. In view of the above, as the current vehicle speed is lower, the determination threshold value to be compared with the brake operation amount is set lower in steps S5 and S6.

  In the memory of the ECU 0, map data that defines the relationship between the traveling speed and deceleration of the vehicle and the determination threshold value to be compared with the brake operation amount is stored in advance. In steps S5 and S6, the ECU 0 searches the map using the traveling speed and deceleration at that time as keys to know the determination threshold value. Then, the brake operation amount at that time is compared with a determination threshold value, and if the brake operation amount exceeds the determination threshold value, an idle stop is started on the assumption that other conditions are satisfied (step S7). If the brake operation amount is below the determination threshold value, the idle stop condition is not satisfied, and it goes without saying that the idle stop is not started.

  In the present embodiment, idle stop is performed to stop the idle rotation of the internal combustion engine when the idle stop condition is satisfied, and the brake operation amount by the driver is a determination threshold value as one of the idle stop conditions. The determination threshold value is variable according to the deceleration of the vehicle, and the determination threshold value when the deceleration is relatively high is lower than the determination threshold value when the deceleration is relatively low. The vehicle control device 0 to be set was configured.

  According to this embodiment, when the automatic transmissions 8 and 9 are in low gear and the deceleration of the vehicle increases, or when the inherent gradient resistance, rolling resistance, etc. are large, the driver who has the intention to stop the vehicle Even if the brake pedal is temporarily released, the idle stop condition is satisfied and the idle stop is started. As a result, the effective idle stop period is lengthened, and wasteful fuel consumption is reduced, which contributes to improvement of fuel consumption performance.

  In addition, the determination threshold value is variable according to the vehicle speed, and the determination threshold value when the vehicle speed is relatively low is set lower than the determination threshold value when the vehicle speed is relatively high. Many can be secured.

  The present invention is not limited to the embodiment described in detail above. The specific configuration of each part and the specific processing procedure can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of a vehicle equipped with an internal combustion engine.

0 ... Control device a ... Vehicle speed signal c ... Accelerator opening signal h ... Master cylinder pressure signal

Claims (2)

A control device for a vehicle that performs an idle stop for stopping an idle rotation of an internal combustion engine when an idle stop condition is satisfied,
One of the idle stop conditions includes that the amount of brake operation by the driver exceeds a determination threshold,
A control apparatus for a vehicle, wherein the determination threshold is variable according to the deceleration of the vehicle, and the determination threshold when the deceleration is relatively high is set lower than the determination threshold when the deceleration is relatively low. The vehicle control device according to claim 1, wherein the determination threshold is variable according to the speed of the vehicle, and the determination threshold when the vehicle speed is relatively low is set lower than the determination threshold when the vehicle speed is relatively high.

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