JP2005246989A - Vehicular control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the slip ratio so that the running fuel consumption of a vehicle is minimized while satisfying the EGR rate to satisfy the exhaust performance request in the vehicle having a lockup clutch on a torque converter. <P>SOLUTION: A vehicular control device comprises a first control device to control the coupling state of a lockup clutch provided on a torque converter and a second control device to control the EGR rate correlated to the surge vibration when coupling the lockup clutch, and obtains the target slip ratio of the lockup clutch at which the fuel consumption is minimized and the limit value of the EGR rate based on the target driving force. By selecting the combination of the slip ratio with the EGR rate so that the fuel consumption is minimized, the running fuel consumption of the vehicle can be reduced as much as possible while satisfying the request for the exhaust performance of an engine and the surge vibration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle control device including a torque converter with a lock-up clutch in a vehicle drive system.

  Some automatic transmission torque converters are provided with a lock-up clutch for fastening the input and output shafts. This is intended to improve the running fuel efficiency of the vehicle by suppressing the inherent relative slip that occurs between the input and output shafts of the torque converter with a lock-up clutch.

However, the use of a lock-up clutch affects not only fuel consumption but also engine exhaust performance and sound vibration performance. For this reason, for example, in Patent Document 1, when the lock-up clutch is not engaged, an optimum EGR rate is selected in consideration of fuel consumption and NOx emission, and when the lock-up clutch is engaged, EGR is selected from the limit of surge vibration generated in the engine to the drive system. I try to suppress the rate. On the other hand, focusing on the fuel efficiency improvement effect, as shown in Patent Document 2, the fuel efficiency during slip control is improved by changing the air-fuel ratio during lean combustion operation according to the slip state of the lockup clutch. What has been proposed.
JP 11-36992 A Japanese Patent Laid-Open No. 2002-21602

  In each of the conventional techniques described above, first, the engagement state or slip ratio of the lock-up clutch is preferentially determined according to the driving state of the vehicle, and engine control amounts such as the EGR ratio and the air-fuel ratio are subordinately determined. Has been decided. For this reason, from the viewpoint of engine control, there is a problem that the best fuel consumption cannot always be obtained when the lockup clutch is used.

  In the present invention, a first control device that controls an engagement state of a lockup clutch provided in the torque converter, and a second control device that controls an engine control amount that correlates with surge vibration at the time of engagement of the lockup clutch. The control device includes a target slip ratio of the lock-up clutch that minimizes the vehicle fuel efficiency (hereinafter referred to as vehicle fuel efficiency), and a limit value of an engine control amount such as an EGR ratio. Is determined based on the target driving force.

  According to the present invention, the combination of the slip ratio and the engine control amount that minimizes the fuel consumption can be selected, and as a result, the vehicle fuel consumption can be as much as possible while satisfying the engine exhaust performance and surge vibration requirements. It becomes possible to reduce.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a vehicle according to an embodiment of the present invention. This vehicle includes a torque converter 2 in the middle of a path for transmitting the output of the engine 1 to a continuously variable transmission (hereinafter referred to as “CVT”) 3. The output of the engine 1 includes the torque converter 2, the CVT 3, and the final gear 4. Is transmitted to the drive wheel 5 via

  The engine 1 is a gasoline engine equipped with an electronically controlled throttle 8 that can be controlled independently of the driver's accelerator operation, and controls the throttle opening of the electronically controlled throttle 8 according to the accelerator pedal operation by the driver. Thus, the engine torque is adjusted. When the engine 1 is a diesel engine, the engine torque is adjusted by adjusting the fuel injection amount with an injector.

  In addition to the impeller 2a, the turbine 2b, and the stator 2c, the torque converter 2 includes a hydraulic lockup clutch 2d that directly connects the impeller 2a and the turbine 2b.

  CVT3 is a belt-type continuously variable transmission that includes a pair of pulleys 3a and 3b and a V-belt 3d wound between them, and the groove widths of the pulleys 3a and 3b are changed via a hydraulic piston 3c, respectively. By doing so, the gear ratio (also referred to as pulley ratio) can be changed steplessly.

  The engine 1 is provided with an EGR passage 15 for communicating the exhaust manifold 14 and the intake surge tank 13 and an EGR valve 16 for controlling the opening degree thereof. In this embodiment, the EGR rate is controlled by the EGR valve 16 as an engine control amount according to the present invention.

  This vehicle is provided with a throttle opening sensor 8, an accelerator opening sensor 9, an engine rotation sensor 10, a turbine rotation sensor 11, a vehicle speed sensor 12, and a water temperature sensor 18 as means for detecting various driving states. Various signals detected by these sensors are input to the engine control device 6 or the transmission control device 7.

  The engine control device 6 and the transmission control device 7 correspond to the second control device and the first control device, respectively, in relation to the present invention, and are configured as a microcomputer including a CPU and its peripheral devices. These control devices 6 and 7 calculate a target driving force based on the input driving conditions, and drive force control that realizes the calculated target driving force with a predetermined engine torque and CVT gear ratio. I do. In addition, the locked state of the lockup clutch 2d is controlled from an open state with a slip ratio of 1 (= 100%) to a fully engaged state with a slip ratio of 0 under an operating state corresponding to a predetermined lockup clutch engaging condition. At the same time, the control of the EGR rate is executed under the engine operating condition including the time of the slip rate control.

  Next, the control of the slip ratio and the EGR ratio that minimizes the fuel consumption when the lockup clutch is engaged under the above configuration will be described. 2 and 3 are a flowchart and a functional block diagram, respectively, showing a first embodiment relating to the control. The control routine shown in FIG. 2 is periodically executed by the control devices 6 and 7 while the lockup is permitted in the shift control. In the following description and flowcharts, the numbers indicated with the symbol S are the process step numbers of the control routine.

  In S101, the accelerator opening, the vehicle speed, and the engine coolant temperature are obtained. This uses the signals of the accelerator opening sensor 9, the vehicle speed sensor 12, and the water temperature sensor 18 shown in FIG.

  In S102 and S103, a target driving force 200 and a target turbine rotational speed 201 are obtained by map search from the accelerator opening and the vehicle speed, respectively.

  In S104 to 105, the target turbine torque 303 is obtained by dividing the target driving force 200 by the actual gear ratio equivalent value obtained by dividing the turbine rotational speed 201 by the vehicle speed.

  In S106 to 107, a map in which the optimum fuel efficiency slip ratio 202 is assigned in advance according to the target turbine rotational speed 201 and the target turbine torque 303 is searched to set the target slip ratio. This map is provided for each water temperature, and the search is performed by selecting a map corresponding to the water temperature at that time. As illustrated in FIG. 4, the map shows the best vehicle fuel efficiency in the combination of the limit value of the slip ratio and the EGR ratio (minimum EGR ratio value that satisfies the surge vibration request and the NOx value request) in advance. It is a map set so that a slip ratio may be given from a result obtained experimentally with respect to torque and turbine rotational speed.

  In S108 to 109, a map in which the optimum EGR rate 203 is assigned in advance according to the target turbine rotational speed 201 and the target turbine torque 303 is searched to set the target EGR rate. This map is provided for each water temperature, and the search is performed by selecting a map corresponding to the water temperature at that time. As illustrated in FIG. 5, this map shows the optimum EGR based on the result obtained by experimentally determining the best vehicle fuel consumption point among the combinations of the slip ratio and the EGR ratio in advance with respect to the turbine torque and the turbine rotation speed. A map set to give a rate.

  Although the two types of maps are separately illustrated here, they are configured as a single map that gives a combination of a slip ratio and an EGR ratio that provides the best vehicle fuel efficiency based on the turbine rotation speed and the turbine torque. You can also.

  FIG. 6 shows a timing chart when the slip ratio and the EGR ratio are controlled by the above control in comparison with the conventional control. Conventionally, the lock-up clutch is completely engaged preferentially or forcibly under the lock-up permission condition, so that the EGR rate applicable to the engine operating state after engagement is restricted, and the fuel consumption is not necessarily the best. . On the other hand, in the present invention, the slip ratio itself related to the lock-up operation is controlled so as to achieve the best fuel efficiency while applying the EGR rate limit value, so that the best vehicle fuel efficiency can be achieved while satisfying the surge vibration demand and the exhaust performance demand. Can be achieved. In this embodiment, the combination of the optimum slip ratio and EGR ratio according to the cooling water temperature corresponding to the characteristic that surge vibration is likely to occur at lower temperatures or the characteristic that the required EGR rate tends to decrease at lower temperatures. Therefore, the slip ratio can be optimally controlled regardless of the warm-up state of the engine.

  FIGS. 7 and 8 are a flowchart and a functional block diagram, respectively, showing a second embodiment relating to the control. The process up to obtaining the target turbine rotation speed and the target turbine torque based on the accelerator opening and the vehicle speed is the same as that shown in FIG.

  That is, in S201, the accelerator opening, the vehicle speed, and the engine coolant temperature are obtained, and in S202 and S203, the target driving force 200 and the target turbine rotational speed 201 are obtained by map search from the accelerator opening and the vehicle speed, respectively. Further, in S204 to 205, the target turbine torque 303 is obtained by dividing the target driving force 200 by the actual gear ratio equivalent value obtained by dividing the turbine rotational speed 201 by the vehicle speed.

  In this embodiment, the target turbine rotation speed, the target turbine torque, the EGR rate limit value for the slip rate under the coolant temperature, the fuel consumption rate of the engine at the EGR rate, and the transmission of the vehicle drive system including the torque converter for the slip rate. It is characterized in that three relations of efficiency are set as a function or a map, and a point where the vehicle fuel consumption becomes the best is searched in the variable range of the slip ratio.

  In S206, first, the slip ratio is set to 0 as an initialization process. Next, in S207, the transmission efficiency of the drive system at the current slip ratio is obtained.

  In S208, the limit value of the EGR rate in the slip rate is obtained.

  In S209, the fuel consumption rate of the engine at the limit value of the EGR rate is obtained.

  In S210, a vehicle fuel consumption equivalent value is calculated based on the engine fuel consumption and transmission efficiency.

  In S211 to 214, the processes in S207 to 210 are repeated while adding a predetermined increment ΔSlip to the slip ratio until the slip ratio reaches the maximum value (= 1).

  In this way, the vehicle fuel consumption at the slip rate is calculated while changing the slip rate from the minimum value to the maximum value by a predetermined increment, and the slip rate and the EGR rate at which the best fuel consumption is obtained are calculated. Set as the target slip ratio and target EGR ratio, respectively. According to this process, it is possible to set the slip ratio and the EGR ratio that provide the best traveling fuel consumption while satisfying the surge vibration demand and the exhaust performance demand relatively easily by changing only one parameter called the slip ratio. it can.

  The processing of S207 to S209 may be obtained by setting a function so as to derive a target amount using a slip ratio or the like as an argument, but the result of each processing depends on the specifications of the engine, the driving device, etc. Therefore, it is possible to search for a map of the results.

  In the above embodiment, an example in which the EGR rate is controlled as an engine control amount correlated with surge vibration is shown. However, other engine control amounts can of course be applied. For example, a variable valve operating device for an internal combustion engine The same effect can be expected when the valve operation timing, air-fuel ratio, or the like is used as the control amount.

1 is a schematic configuration diagram of a vehicle to which the present invention is applicable. The flowchart showing the processing content of 1st Embodiment regarding the control of this invention. The block diagram showing the control function of the said 1st Embodiment. Explanatory drawing of an example of the slip ratio map applied to the said 1st Embodiment. Explanatory drawing of an example of the EGR rate map applied to the said 1st Embodiment. The timing chart which shows the control result of the said 1st Embodiment. The flowchart showing the processing content of 2nd Embodiment regarding the control of this invention. The block diagram showing the control function of the 2nd Embodiment of this invention.

Explanation of symbols

1 Engine 2 Torque converter 2d Lock-up clutch 3 Continuously variable transmission (CVT)
6 Engine controller (second controller)
7. Transmission control device (first control device)
8 Electronic control throttle 9 Accelerator opening sensor 10 Engine rotation sensor 11 Turbine rotation sensor 12 Vehicle speed sensor 15 EGR passage 16 EGR valve 18 Water temperature sensor

Claims (11)

A vehicle comprising: a first control device that controls an engagement state of a lockup clutch provided in a torque converter; and a second control device that controls an engine control amount correlated with surge vibration when the lockup clutch is engaged. A control device of
Target driving force calculating means for calculating the target driving force based on the driving state of the vehicle;
Of the combinations of the slip rate at which the target driving force can be achieved and the limit value of the engine control amount that satisfies the surge vibration requirement at the slip rate, the combination that minimizes the vehicle fuel consumption is obtained, and the combination with the minimum fuel consumption is determined. A vehicle control device comprising target value setting means for providing the slip ratio and the engine control amount to the first control device and the second control device, respectively. A vehicle comprising: a first control device that controls an engagement state of a lockup clutch provided in a torque converter; and a second control device that controls an engine control amount that correlates with surge vibration when the lockup clutch is engaged. A control device of
Target driving force calculating means for calculating the target driving force based on the driving state of the vehicle;
A target value setting means for providing the first control device and the second control device with a slip ratio and an engine control amount that minimize fuel consumption based on the target driving force,
The target value setting means includes
A procedure for calculating the transmission efficiency of a power transmission device including a torque converter for each different slip ratio;
A procedure for calculating a limit value of an engine control amount that satisfies a surge vibration requirement for each different slip ratio;
A procedure for calculating the fuel consumption rate of the engine from the limit value of the engine control amount;
A procedure for calculating the vehicle fuel consumption from the transmission efficiency and the engine fuel consumption rate is executed, and a combination of a plurality of slip ratios and engine control amounts obtained based on the procedure has a minimum vehicle fuel consumption. A vehicle control device configured to be set as a target value to be given to the first control device and the second control device.   3. The vehicle control device according to claim 1, wherein a demand load represented by a throttle opening or a fuel injection amount and a vehicle speed are detected as an operation state of the vehicle.   The vehicle control device according to claim 1, wherein the engine control amount is an EGR rate.   The vehicle control device according to claim 1, wherein the engine control amount is a valve operation timing of a variable valve mechanism of an internal combustion engine.   The vehicle control device according to claim 1, wherein the engine control amount is an air-fuel ratio.   The vehicle control device according to claim 1, wherein the target driving force calculation means calculates a turbine torque and a turbine rotation speed of a torque converter as a target driving force representative value.   The target value setting means is configured to set the target slip ratio and the target engine control amount by searching a map in which the target slip ratio and the target engine control amount that minimize the vehicle fuel consumption are previously assigned based on the target driving force. The vehicle control device according to claim 1.   The vehicle control device according to claim 8, wherein the map includes a plurality of maps selected for each engine coolant temperature. In the target value setting means,
The procedure for calculating the transmission efficiency is to search a map set in advance so as to give the transmission efficiency for each slip ratio,
The procedure for calculating the engine control amount limit value is by searching a map set in advance so as to give the engine control amount limit value for each slip ratio.
The procedure for calculating the fuel consumption rate of the engine is to search a map preset to give the fuel consumption rate from the limit value of the engine control amount,
The procedure for calculating the vehicle fuel consumption is to search a map set in advance so as to give the vehicle fuel consumption from the transmission efficiency and the engine fuel consumption rate,
The vehicle control device according to claim 2, which is executed respectively.   The vehicle control device according to claim 2, wherein the target value setting means is configured to correct the target value in accordance with an engine coolant temperature.

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