JP6775884B2 - Vehicle control device - Google Patents

Description

The present invention relates to a control device for controlling a vehicle in which a torque converter with a lockup clutch is interposed between an internal combustion engine and an axle.

As an automatic transmission mounted on a vehicle drive system, a continuously variable transmission provided with a torque converter and a belt-type continuously variable transmission mechanism (for example, see the following patent documents) is known.

The torque converter is usually equipped with a lockup clutch that engages the input side and the output side so as not to rotate relative to each other. By locking up the torque converter, it is possible to improve the transmission efficiency of the rotational driving force and improve the practical fuel consumption.

Japanese Unexamined Patent Publication No. 2016-166665

Recently, in order to further pursue the fuel efficiency of vehicles, lock-up of torque converters has been started from a state where the vehicle speed and engine speed are low (for example, at 10 km / h or more, or 1200 rpm or more). There is.

If the torque converter is locked up while the vehicle is traveling on an uphill road, the engine speed drops due to the reverse torque acting on the crankshaft when misfires occur repeatedly in the cylinder of the internal combustion engine, causing the engine to stall. There is a concern that it will fall into.

The present invention has been made by paying attention to the above problems for the first time, and it is intended to prevent an unexpected decrease in the engine speed when a vehicle equipped with a torque converter with a lockup clutch travels on an uphill road. The intended purpose.

The present invention controls a vehicle in which a torque converter with a lockup clutch is interposed between the internal combustion engine and the axle, and in the cylinder of the internal combustion engine , a predetermined number of times or more within a certain period in the past There is history of sensed misfire, the vehicle is traveling on an uphill road, yet the accelerator pedal is stepped over a predetermined, on condition that all the above are satisfied, the current vehicle speed or engine speed and A vehicle control device that prohibits the lockup of the torque converter even if the torque converter should be locked up in view of the amount of depression of the accelerator pedal is configured.

According to the present invention, it is possible to prevent a sudden decrease in the engine speed when a vehicle equipped with a torque converter with a lockup clutch travels on an uphill road.

The figure which shows the schematic structure of the internal combustion engine and the control device of a vehicle in one Embodiment of this invention. The figure which shows the structure of the drive system of the vehicle in the same embodiment. The flow chart which shows the procedure example of the process which the control device of the vehicle of the same embodiment executes according to a program. The figure which shows the operating area which prohibits the lockup of a torque converter in the same embodiment.

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 according to the present embodiment. The internal combustion engine of the present embodiment is a spark-ignition 4-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is illustrated in FIG. 1). An injector 11 for injecting fuel is provided in the vicinity of the intake port of each cylinder 1. Further, a spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives the application of the induced voltage generated by the ignition coil and causes a spark discharge between the center electrode and the ground electrode. The ignition coil is integrally built in the coil case together with the igniter having the 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. 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 on the intake passage 3.

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

The exhaust gas recirculation device 2 realizes a so-called high-pressure loop EGR in which a part of the exhaust gas flowing through the exhaust passage 4 is returned to the intake passage 3 and mixed with the intake air. The EGR device 2 includes an external EGR passage 21 that connects the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. The element is an EGR valve 23 that opens and closes and controls the flow rate of the EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined position downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined position downstream of the throttle valve 32 in the intake passage 3, particularly a surge tank 33.

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

The rotational driving force output by the internal combustion engine is input from the crankshaft, which is the output shaft of the internal combustion engine, to the pump impeller 71 on the input side of the torque converter 7, and is 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 / backward switching device 8, and the driven shaft 95 is rotated through the shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 151. The output gear 151 meshes with the ring gear 152 of the differential device to rotate the axle 153 and the drive wheels (not shown) via the differential device.

The torque converter 7 includes a lockup mechanism. The lockup mechanism is known in this field, and is an operation for connecting / disconnecting and switching between a lockup clutch 73 that engages the input side and the output side of the torque converter 7 so as not to rotate relative to each other. The element is a lockup solenoid valve (not shown) that controls hydraulic pressure (hydraulic pressure). The lockup solenoid valve is a flow rate control valve that receives a control signal t and changes its opening degree.

In a vehicle equipped with the CVT 9, when the vehicle speed is a certain level (for example, 10 km / h) or more, the torque converter 7 is almost always locked up. When the vehicle speed becomes lower than that, the lockup of the torque converter 7 is released. At the time of lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates integrally with the torque converter cover 74. At the time of lockup, the rotational driving force input to the input side (drive plate) of the torque converter 7 is applied to the output side of the torque converter 7 via the lockup clutch 73 from the torque converter cover 74, and eventually to the forward / backward switching device 8. Is transmitted directly to. At the time of lockup, the speed ratio, which is the ratio of the output side rotation speed of the torque converter 7 to the input side rotation speed, is 1.

On the other hand, when not locked up, the lockup clutch 73 separates from the torque converter cover 74. At the time of non-lockup, the rotational driving force 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 / backward switching device 8. At the time of non-lockup, the speed ratio of the torque converter 7 becomes smaller or larger than 1 depending on the driving state.

The forward / reverse switching device 8 has a sun gear 81 in contact with the turbine runner 72 and a ring gear 82 in contact with the drive shaft 94. A forward brake 84, which is a hydraulic clutch that can be switched between disconnection and disconnection, is interposed between the planetary carrier 83 that supports the planetary gear 831 and the transmission case. Further, a reverse clutch 85, which is a hydraulic clutch that can be switched between disconnection and 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 disengaged. 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, resulting in forward traveling. On the other hand, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disengaged. 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 each other to drive in reverse. The solenoid valve (not shown) that controls the hydraulic pressure for disconnecting and switching the forward brake 84 or the reverse clutch 85 is a flow rate control valve that receives a control signal u to change its opening degree.

In the N range of the non-traveling range, both the forward brake 84 and the reverse clutch 85 are disengaged. In the P range, the axle 153 is mechanically locked so that it does not move.

The CVT 9 includes a drive pulley 91 and a driven pulley 92, and a belt 93 wound around both pulleys 91 and 92 as elements. The drive pulley 91 is arranged on the rear back of the fixed sheave 911 fixed to the drive shaft 94, the movable sheave 912 supported on the drive shaft 91 so as to be displaced in the axial direction via a roller spline, and the movable sheave 912. It has a hydraulic servo 913, and the gear ratio can be changed steplessly by operating the hydraulic servo 913 to displace the movable sheave 912. Further, the driven pulley 92 is arranged on the rear back of the fixed sheave 921 fixed to the driven shaft 95, the movable sheave 922 supported on the driven shaft 95 so as to be displaced in the axial direction via a roller spline, and the movable sheave 922. It has the hydraulic pressure servo 923 provided, and gives the belt thrust necessary for torque transmission by operating the hydraulic pressure servo 923 and displacing the movable sheave 922.

The ECU (Electronic Control Unit) 0, which is a vehicle 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 of ECU0 is output from the vehicle speed signal a output from the vehicle speed sensor that detects the actual vehicle speed of the vehicle, the rotation angle of the crank shaft of the internal combustion engine, and the crank angle sensor (engine rotation sensor) that detects the engine rotation speed. Crank angle signal b, accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal as the accelerator opening (so to speak, the required load on the internal combustion engine), in the intake passage 3 (particularly, surge tank 33). Intake temperature / intake pressure signal d output from the temperature / pressure sensor that detects the intake air temperature and pressure, inclination signal e output from the inclination sensor or acceleration sensor that detects the inclination of the road surface where the vehicle is currently located, The cooling water temperature signal f output from the water temperature sensor that detects the cooling water temperature suggesting 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 intake cam shaft or the exhaust cam shaft, and the vehicle. The shift range signal h or the like output from the sensor for knowing the range (D range, N range, R range, P range, etc.) of the shift lever (select lever) of is input.

From the output interface of ECU 0, ignition signal i for the igniter 13, fuel injection signal j for the injector 11, opening operation signal k for the throttle valve 32, opening operation signal l for the EGR valve 23, Opening operation signal t for the lockup solenoid valve for disconnection / disconnection switching of the lockup clutch 73, opening operation signal u for the solenoid valve for disconnection / disconnection switching of the forward brake 84 or reverse clutch 85, and CVT9. Outputs the gear ratio control signal v and the like.

The processor of ECU 0 interprets and executes a program stored in the memory, calculates an operation parameter, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, h necessary for the operation control of the internal combustion engine via the input interface, obtains the engine speed, the intake pressure, and the like, and also obtains the cylinder. Required fuel injection amount, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR amount), torque converter corresponding to the intake amount charged in 1. Various operating parameters such as whether or not to lock up 7 and the gear ratio of the CVT 9 are determined. The ECU 0 applies various control signals i, j, k, l, t, u, and v corresponding to the operation parameters via the output interface.

Normally, the ECU 0 determines whether to engage or disengage the lockup clutch 73 of the torque converter 7 according to the vehicle speed, the engine speed, and the amount of depression of the accelerator pedal. Basically, the torque converter 7 is locked up from a state where the vehicle speed and the engine speed are low, for example, when the vehicle speed is about 10 km / h or more and the engine speed is about 1200 rpm or more. In the memory of the ECU 0, map data that defines the relationship between the vehicle speed, the engine speed, the amount of depression of the accelerator pedal, and whether or not to lock up the torque converter 7 is stored in advance. The ECU 0 searches the map using the current vehicle speed, engine speed, and accelerator pedal depression amount as keys, and knows whether or not the torque converter 7 needs to be locked up.

Further, the ECU 0 measures the rotation speed of the crankshaft of the internal combustion engine per predetermined rotation angle, and compares the decrease amount (change amount) of the rotation speed with the determination threshold value, so that a misfire occurs in the cylinder 1. Judge whether or not. More specifically, the time required for the crankshaft to rotate at a predetermined rotation angle, for example, 30 ° CA (crank angle) is repeatedly measured via the crank angle sensor, and the previous measurement is performed from the required time measured this time. By subtracting the required time, the amount of change in the required time of 30 ° CA, which is an index of the amount of decrease in the rotation speed for each 30 ° CA, is obtained. A positive value of the change in the required time of 30 ° CA means that the rotation speed of the internal combustion engine tends to decelerate, and a negative value means that the rotation speed of the internal combustion engine tends to accelerate. To do. When a misfire occurs in the cylinder 1, acceleration is not performed in the expansion stroke of the cylinder 1, so that the value of the amount of change in the required time of 30 ° CA gradually increases. Therefore, the ECU 0 compares the amount of change in the required time of 30 ° CA with the determination threshold value, and determines that a misfire has occurred in the cylinder 1 if the former exceeds the latter.

Therefore, as shown in FIG. 3, the ECU 0 of the present embodiment has a history of detecting a misfire more than a predetermined number of times within a certain period in the past, for example, while the crankshaft has rotated a predetermined number of times (step S1). The engine speed is equal to or less than the threshold value of the predetermined low speed, and the engine load (engine torque, opening degree of throttle valve 32, intake pressure in surge tank 33, intake amount filled in cylinder 1 (fresh air amount). (There is) or the fuel injection amount) is equal to or greater than the predetermined high load threshold (step S2), and the amount of depression of the accelerator pedal is equal to or greater than the predetermined value (step S3), and the lockup of the torque converter 7 is prohibited. (Step S4). That is, even if the lockup clutch 73 should be engaged in view of the current vehicle speed, engine speed, and accelerator pedal depression amount, the lockup clutch 73 was not engaged or was engaged. Open 73.

In step S2, it is determined whether or not the vehicle is currently traveling on an uphill road. When the current operating region of the internal combustion engine is in the hatched region in FIG. 4, it is presumed that the engine speed is low despite the high engine load, that is, the vehicle is traveling on an uphill road. Further, in step S3, it is determined whether or not the driver has an intention to continue traveling without stopping the vehicle.

The determination condition in step S2, that is, the threshold value to be compared with the engine speed and the threshold value to be compared with the engine load may be made variable according to the amount of decrease in the engine speed or the vehicle speed per unit time at that time. Specifically, when the amount of decrease in engine speed or vehicle speed per unit time is large, the threshold value to be compared with the engine speed is set as compared with the case where the amount of decrease in engine speed or vehicle speed per unit time is small. By further raising and / or lowering the threshold value to be compared with the engine load, the operating range in which the lockup of the torque converter 7 is prohibited is expanded. In FIG. 4, the solid line represents the threshold value when the amount of decrease in engine speed or vehicle speed per unit time is relatively small, and the chain line represents the threshold value when the amount of decrease in engine speed or vehicle speed per unit time is relatively large. Represents. When the amount of decrease in the engine speed or the vehicle speed per unit time becomes large, the operating region in which the lockup of the torque converter 7 is prohibited expands to the shaded region in FIG.

In the present embodiment, the vehicle in which the torque converter 7 with the lockup clutch 73 is interposed between the internal combustion engine and the axle 153 is controlled, and the cylinder 1 of the internal combustion engine has misfired a plurality of times. When detected, the vehicle control device 0 that prohibits the lockup of the torque converter 7 is set on the condition that the engine speed is equal to or lower than the predetermined threshold, the engine load is equal to or higher than the predetermined threshold, and the accelerator pedal is depressed more than the predetermined threshold. Configured.

According to the present embodiment, there is a possibility that some abnormality (such as the necessary and sufficient amount of fuel not being injected from the injector 11 or the spark plug 12 is contaminated and spark ignition does not work) has occurred in the internal combustion engine, resulting in continuous misfires. In addition, since it is prohibited to lock up the torque converter 7 while traveling on an uphill road, it is possible to prevent a large reverse torque from acting on the crankshaft of the internal combustion engine from the uphill road via the drive system. As a result, it is possible to avoid the problem that the engine speed drops unreasonably while traveling on an uphill road and the engine stalls. Then, the vehicle can be evacuated to a safe place.

Further, when step S2 is not established and the vehicle is not traveling on an uphill road, in other words, when traveling on a flat road or a downhill road, the torque converter 7 is allowed to lock up to maintain fuel efficiency. Try.

The present invention is not limited to the embodiments described in detail above. When the conditions of steps S1 to S3 are all satisfied, the lockup of the torque converter 7 may be prohibited, and the opening degree of the EGR valve 23 may be reduced or fully closed to reduce or reduce the amount of EGR gas recirculation. , Effective in preventing engine stalls. Further, when the conditions of steps S1 to S3 are all satisfied, the load of the auxiliary machine driven by the internal combustion engine is reduced, for example, the power generation amount (or output voltage) of the generator is reduced, or the air conditioner is used. It is also preferable to prohibit the operation of the refrigerant compression compressor or reduce the capacity of the variable displacement compressor.

In step S2, instead of determining the operating area of the internal combustion engine, the inclination of the road surface where the vehicle is currently located may be directly detected via the inclination sensor or the acceleration sensor. In that case, it is considered that the condition of step S2 is satisfied when the slope of the road surface is an ascent of a predetermined angle or more.

The method for detecting the occurrence of misfire in the cylinder 1 of the internal combustion engine is not limited to the one that refers to the amount of decrease in the rotational speed per predetermined rotation angle of the crankshaft. For example, it is possible to detect the ion current generated when the air-fuel mixture burns in the combustion chamber of the cylinder 1 and determine the presence or absence of misfire by referring to the ion current signal.

In addition, the specific configuration of each part, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

The present invention can be applied to control a lockup clutch of a torque converter of a vehicle drive system.

0 ... Control unit (ECU)
1 ... Cylinder 7 ... Torque converter 73 ... Lockup clutch 153 ... Axle a ... Vehicle speed signal b ... Crank angle signal c ... Accelerator opening signal e ... Tilt signal j ... Fuel injection signal k ... Opening operation signal t ... Opening operation signal

Claims (1)

It controls a vehicle in which a torque converter with a lockup clutch is interposed between the internal combustion engine and the axle.
There is a history of detecting misfires more than a predetermined number of times in the past certain period in the cylinder of an internal combustion engine .
The vehicle is running on an uphill road
Moreover, the accelerator pedal is depressed more than the specified value .
On condition that all of the above are satisfied, the lockup of the torque converter is prohibited even if the torque converter should be locked up in view of the current vehicle speed or engine speed and the amount of depression of the accelerator pedal. Vehicle control device.

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