Vehicle control device

Abstract

To inhibit fuel increase control for suppressing overheating from being executed when a temperature of an exhaust system rises in the case where an ignition delay angle method is used as torque-down control in gear change.SOLUTION: When there is a request for torque-down control in gear change, a temperature of a predetermined part in the case where an ignition delay angle method is used is predicted. If the predicted temperature (THcat +Δtcat) and (THex+Δtex) is a predetermined upper limit temperature THcatmax, THexmax or higher (the determination in S4 or S5 being NO), a fuel cut method is selected in S8 and torque-down control in gear change is executed. By appropriately determining the upper limit temperature THcatmax, THexmax, execution frequency of fuel increase control by an overheating suppression control part is reduced, and an increase in harmful gas such as HC and CO due to fuel increase can be suppressed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle, and more particularly to a control device for a vehicle that performs torque-down control during gear shifting of an automatic transmission.

Background Art

[0002] (a) Regarding a vehicle including an engine and an automatic transmission that transmits power from the engine to the drive wheel side, (b) when shifting gears of the automatic transmission, a control device for a vehicle that performs torque-down control during gear shifting using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply is known. The device described in Patent Document 1 is an example thereof, and as a fuel cut method, a partial fuel cut control for stopping fuel supply to some cylinders of the engine and a closing control for reducing the throttle valve opening are described. Further, when the temperature related to the exhaust system of the engine rises, fuel increment control for increasing the fuel supply amount to the engine is performed to suppress overheating. On the other hand, when in the middle of fuel increment control during gear shifting, the ignition retard method and the fuel cut method are switched based on the change amount of the increment coefficient.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the exhaust system temperature rises due to the execution of torque-down control during gear shifting using the ignition retard method and fuel increment control becomes necessary, harmful gases such as HC and CO in the exhaust gas may increase due to the fuel increment, and there is still room for improvement. According to the fuel cut method, there is no risk of overheating, and the possibility of fuel increment control is low. However, for example, due to poor control accuracy and responsiveness of the intake air volume and fuel injection volume, the rise of engine torque at the time of resuming fuel supply after torque-down control during gear shifting becomes slow, and the power performance may be impaired compared to the ignition retard method.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to suppress the increase in the temperature of the exhaust system and the execution of fuel increment control for overheat suppression when the ignition retard method is used as the torque-down control during gear shifting.

Means for Solving the Problems

[0006] In order to achieve such an object, a first invention relates to a vehicle including (a) an engine and (b) an automatic transmission that transmits the power from the engine to the drive wheel side. In a control device for the vehicle, (c) when a request for torque-down control during gear shifting is made, the temperature of a predetermined portion of the exhaust pipe of the engine when the ignition retard method is used is predicted, and when the predicted temperature of the predetermined portion is equal to or higher than a predetermined upper limit temperature, the torque-down control during gear shifting is performed using the fuel cut method. When performing the shift torque down control using the fuel cut method in step (d), while restricting the fuel supply, open and control the engine's electronic throttle valve characterized by the above.

[0008] The 2 second invention is (a) Regarding a vehicle equipped with an engine and an automatic transmission that transmits the power from the engine to the drive wheel side, (b) in a vehicle control device that performs shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply when shifting the automatic transmission, (c) when a request for the shift torque down control is made, predict the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method, (e) the temperature of the predetermined portion is the temperature of a catalyst provided in the exhaust pipe, (f)When the current temperature of the catalyst is equal to or higher than a predetermined lean deterioration temperature at which deterioration of the catalyst is a concern in the case of the fuel cut method, the ignition retard method is used to perform the shift torque down control regardless of whether the predicted temperature is equal to or higher than the upper limit temperature. This is the gist of the invention.

[0009] No. 3 The invention is (a) Regarding a vehicle equipped with an engine and an automatic transmission that transmits the power from the engine to the drive wheel side, (b) in a vehicle control device that performs shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply when shifting the automatic transmission, (c) when a request for the shift torque down control is made, predict the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method, (g) The temperature of the predetermined part is the temperature of the catalyst provided in the exhaust pipe and the temperature of the exhaust gas that rotates the turbine of the turbocharger provided in the engine. (h) The predicted temperature of the catalyst and the predicted temperature of the exhaust gas are calculated respectively, and it is determined whether or not these predicted temperatures are equal to or higher than the upper limit temperatures separately determined for the catalyst and the exhaust gas. When either one of them is equal to or higher than the upper limit temperature, the shift torque down control is performed using the fuel cut method. This is the gist of the invention.

[0010] No. 4 The invention is (a) Regarding a vehicle equipped with an engine and an automatic transmission that transmits the power from the engine to the drive wheel side, (b) in a vehicle control device that performs shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply when shifting the automatic transmission, (c) when a request for the shift torque down control is made, predict the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method, (i) When the temperature of the predetermined part of the exhaust pipe reaches a predetermined overheat determination temperature, the control device has an overheat suppression control unit that performs fuel increment control to increase the fuel supply amount to the engine in order to suppress overheating of the predetermined part. (j) The upper limit temperature is determined based on the overheat determination temperature so that the execution of the fuel increment control by the overheat suppression control unit is suppressed. This is the gist of the invention.

Advantages of the Invention

[0011] In such According to the first invention In the vehicle control device, the temperature of a predetermined part of the engine exhaust pipe when using the ignition retard method is predicted, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, the shift torque down control is performed using the fuel cut method. Therefore, by appropriately setting the upper limit temperature, the execution frequency of the fuel increment control for suppressing overheating is reduced, and an increase in harmful gases such as HC and CO caused by the fuel increment can be suppressed. Also, when performing shift torque down control using a fuel cut method, the electronic throttle valve of the engine is opened and controlled while restricting fuel supply. For this reason, a predetermined intake air amount is ensured even during shift torque down control by the fuel cut method, and the engine torque is rapidly increased along with the resumption of fuel supply after the shift torque down control, improving the response delay.

[0013] Invention 2 invention Control device for vehicle When predicting the temperature of a catalyst provided in an exhaust pipe and performing shift torque down control, when the current temperature of the catalyst is equal to or higher than the lean degradation temperature, the ignition retard method is used to perform shift torque down control regardless of whether the predicted temperature is equal to or higher than the upper limit temperature. For this reason, although fuel increment control may be executed due to overheating, it is possible to avoid deterioration of the catalyst due to a lean atmosphere as in the fuel cut method.

[0014] Invention 3 invention Control device for vehicle Invention calculates the predicted temperature of the catalyst and the predicted temperature of the exhaust gas, respectively, and determines whether or not these predicted temperatures are equal to or higher than the upper limit temperatures separately defined for the catalyst and the exhaust gas. When either one is equal to or higher than the upper limit temperature, shift torque down control is performed using the fuel cut method. For this reason, execution of fuel increment control for suppressing overheating is appropriately suppressed.

[0015] Invention 4 invention Control device for vehicle Invention has an overheat suppression control unit that executes fuel increment control for suppressing overheating when the overheat determination temperature is reached, and the upper limit temperature is determined based on the overheat determination temperature so that execution of fuel increment control is suppressed. For this reason, the effect of the present invention of reducing the execution frequency of fuel increment control and suppressing an increase in harmful gases such as HC and CO is appropriately obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiment for Carrying Out the Invention

[0017] The engine is an internal combustion engine such as a gasoline engine or a diesel engine that can reduce engine torque by an ignition retard method and a fuel cut method. As the automatic transmission, for example, a stepped transmission such as a planetary gear type or a two-shaft meshing type in which a plurality of gear stages with different gear ratios are alternatively formed is preferably used, but a continuously variable transmission such as a belt type that can continuously change the gear ratio can also be used. The torque down control during gear shifting is adopted, for example, to quickly reduce the engine speed when shifting to a high-speed gear stage with a small gear ratio in the driving force generation state (power-on state), but torque down control may also be performed immediately before the end of gear shifting even during a power-on downshift. The present invention is applied to various torque down controls during gear shifting.

[0018] The present invention predicts the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method when torque down control during gear shifting is required, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, torque down control during gear shifting is implemented using the fuel cut method. When the predicted temperature is lower than the upper limit temperature, either the ignition retard method or the fuel cut method may be used. For example, an ignition retard method with excellent control accuracy and responsiveness of the intake air amount and fuel injection amount may be used. However, since the ignition retard method and the fuel cut method each have advantages and disadvantages, one of them may be selected based on the driving state of the vehicle, driving conditions, and driving intentions of the driver at that time.

[0019] When performing shift torque down control using a fuel cut method, it is desirable to open and control the electronic throttle valve while restricting fuel supply. However, shift torque down control by the fuel cut method may also be performed with the electronic throttle valve closed. The temperature of a predetermined part is, for example, the temperature of a catalyst provided in the exhaust pipe or the temperature of the exhaust gas that rotates the turbine of the turbocharger, and either one or both of these temperatures can be targeted. However, it may also be the temperature of other components provided in the exhaust pipe or the like. Instead of the exhaust gas that rotates the turbine, the temperature of the turbine itself or the temperature of the exhaust pipe may be used.

Embodiment

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram for explaining the schematic configuration of a drive device of a vehicle 10 equipped with an electronic control unit 70 as a control device according to an embodiment of the present invention, and is also a diagram for explaining the main part of a control system provided in the vehicle 10. Further, FIG. 2 is a diagram for explaining the schematic configuration of the engine 12 in FIG. 1, and is also a diagram for explaining the main part of a control system provided in the vehicle 10 for executing output control etc. of the engine 12. The vehicle 10 is an engine-driven vehicle equipped only with the engine 12 as a power source for traveling. The power generated by the engine 12 is input to the input shaft 16 of the automatic transmission 18 via the torque converter 14, and is transmitted from the output shaft 20 of the automatic transmission 18 to the left and right drive wheels 26 through the differential gear device 22, a pair of axles 24, etc. in sequence.

[0021] Engine 12 is, for example, a known gasoline engine for automobiles having a plurality of cylinders. As shown in FIG. 2, it includes an intake pipe 32 connected to the intake port of the combustion chamber 30, an exhaust pipe 34 connected to the exhaust port of the combustion chamber 30, a fuel injection device 36 for injecting and supplying fuel F to the intake air inhaled into the combustion chamber 30, and an ignition device 38 for igniting the air-fuel mixture in the combustion chamber 30 composed of the fuel F injected and supplied by the fuel injection device 36 and the inhaled air. An electronic throttle valve 40 is provided in the intake pipe 32 of the engine 12, and the electronic throttle valve 40 is opened and closed by a throttle actuator 42. In this engine 12, fuel F is injected and supplied from the fuel injection device 36 to the intake air inhaled from the intake pipe 32 into the combustion chamber 30 to form an air-fuel mixture, and the air-fuel mixture in the combustion chamber 30 is ignited by the ignition device 38 and burns and explodes. As a result, while the piston of the engine 12 is driven up and down and the crankshaft is rotated, the air-fuel mixture after combustion is discharged to the outside through the exhaust pipe 34 as exhaust gas EX.

[0022] A catalyst 44 is provided in the exhaust pipe 34 of the engine 12. The exhaust gas EX generated by the combustion of the engine 12 flows into the catalyst 44 through the exhaust pipe 34, is purified by the catalyst 44, and is discharged into the atmosphere. This catalyst 44 is composed of, for example, a well-known three-way catalyst that purifies hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), etc. in the exhaust gas EX. A turbine rotation drive unit 46 is also provided between the engine 12 and the catalyst 44 in the exhaust pipe 34, and the turbine of a turbocharger 48 disposed across the exhaust pipe 34 and the intake pipe 32 is rotationally driven by the exhaust gas EX.

[0023] The automatic transmission 18 forms part of the power transmission path from the engine 12 to the drive wheels 26, and transmits the power from the engine 12 to the drive wheel 26 side. The automatic transmission 18 is a known planetary gear type automatic transmission in which shifting is performed, for example, by changing the engagement of any of a plurality of engaging devices, that is, by switching between the engagement and release of the engaging devices, and a plurality of gear stages with different gear ratios are selectively established. That is, the automatic transmission 18 is a stepped transmission that performs so-called clutch-to-clutch shifting, and shifts the rotation of the input shaft 16 and outputs it from the output shaft 20. This input shaft 16 is also a turbine shaft that is rotationally driven by the turbine impeller of the torque converter 14. The plurality of engaging devices are respectively controlled for engagement and release by a hydraulic control circuit 28, and the torque capacity, that is, the engaging force of each is changed by adjusting the pressure of a solenoid valve or the like in the hydraulic control circuit 28, and it is a hydraulic friction engaging device such as a clutch or a brake that selectively connects the members on both sides where it is inserted.

[0024] The vehicle 10 is equipped with an electronic control unit 70 that executes, for example, output control of the engine 12 and shift control of the automatic transmission 18. The electronic control unit 70 is configured to include a so-called microcomputer including, for example, a CPU, a RAM, a ROM, an input / output interface, etc., and the CPU performs signal processing according to a program stored in the ROM in advance while using the temporary storage function of the RAM to execute various controls of the vehicle 10. The electronic control unit 70 is configured separately into, for example, an engine control unit and a shift control unit as necessary. This electronic control unit 70 corresponds to the control unit of the vehicle 10.

[0025] The electronic control unit 70 is supplied with signals representing various types of information necessary for various controls, such as an engine rotation speed sensor 50, a transmission input rotation speed sensor 52, a transmission output rotation speed sensor 54, an accelerator opening sensor 56, a throttle valve opening sensor 58, an air flow meter (intake air amount sensor) 60, a coolant water temperature sensor 62, an exhaust gas temperature sensor 64, a catalyst temperature sensor 66, etc., including an engine rotation speed Ne representing the rotation speed of the engine 12, a turbine rotation speed Nt representing the rotation speed of the input shaft 16, i.e., the transmission input rotation speed Nin, a transmission output rotation speed Nout representing the rotation speed of the output shaft 20 corresponding to the vehicle speed V, an accelerator opening Acc which is an operation amount of an accelerator pedal or the like representing the driver's required amount for the driving force of the vehicle 10 (the same applies to driving torque, etc.), a throttle valve opening θth representing the opening angle of the electronic throttle valve 40, an intake air amount Qair of the engine 12, a coolant water temperature THw of the engine 12, an exhaust gas temperature THex which is the temperature of the exhaust gas EX upstream of the turbine rotation driving unit 46 (i.e., the exhaust gas EX flowing into the turbine rotation driving unit 46), a catalyst temperature THcat, etc. From the electronic control unit 70, for example, an engine control command signal Se for performing output control of the engine 12, a hydraulic control command signal Sp for operating a hydraulic control circuit 28 that controls a hydraulic actuator of the automatic transmission 18, etc. are respectively output.

[0026] The electronic control unit 70 functionally includes an engine control section 72, an overheat suppression control section 74, a shift control section 76, and a torque down control section 78.

[0027] The engine control unit 72 calculates the driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening Acc and the vehicle speed V to the driving demand amount map. The driving demand amount is, for example, the required driving torque Trdem at the driving wheels 26 or the like. The engine control unit 72 obtains the required input torque Tindem, which is the input torque of the torque converter 14 necessary to achieve the required driving torque Trdem, from the gear ratio of the automatic transmission 18, the torque ratio of the torque converter 14, and the like, and controls the engine 12 so that the required input torque Tindem can be obtained. Specifically, in addition to controlling the opening and closing of the electronic throttle valve 40 by the throttle actuator 42 so that the engine torque Te, which is the torque of the engine 12, becomes the required input torque Tindem, the fuel injection amount (fuel supply amount) by the fuel injection device 36 is controlled for fuel injection control to each cylinder of the engine 12, and the ignition device 38 is controlled for ignition timing control, and an engine control command signal Se is output.

[0028] When the temperature related to the exhaust system of the engine 12 rises, the overheat suppression control unit 74 executes fuel increment control to increase the fuel injection amount to the engine 12. Specifically, as the temperature related to the exhaust system of the engine 12, the catalyst temperature THcat, which is the temperature of the catalyst 44, is used. When the catalyst temperature THcat becomes equal to or higher than a predetermined overheat determination temperature THcath for determining that the purification ability of the catalyst 44 has decreased to a high temperature, fuel increment control is executed. In this case, the fuel increment control increases the fuel injection amount by multiplying the fuel injection amount (command value) when the fuel increment control is not executed by a predetermined increment coefficient Kcat (>1), thereby reducing the exhaust gas temperature THex and cooling the catalyst 44. The increment coefficient Kcat becomes a larger value as the ignition timing of the engine 12 is more retarded (the larger the ignition retard amount Φ), and becomes a larger value as the accelerator opening Acc or the throttle valve opening θth is larger. The ignition retard amount Φ, the accelerator opening Acc, the throttle valve opening θth, etc. are defined as variables so that the fuel increment amount becomes larger. The catalyst temperature THcat is detected by the catalyst temperature sensor 66, but an estimated value calculated from the intake air amount Qair corresponding to the engine load, the engine rotational speed Ne, etc., or calculated from the exhaust gas temperature THex can also be used.

[0029] The overheat suppression control unit 74 also uses the exhaust gas temperature THex, which is the temperature of the exhaust gas EX, as the temperature related to the exhaust system of the engine 12, and when the exhaust gas temperature THex becomes equal to or higher than a predetermined overheat determination temperature THexh for determining that the temperature is high enough to inhibit or damage the operation in the turbine rotation drive unit 46, it executes fuel increment control. The fuel increment control at this time increases the fuel injection amount by multiplying the fuel injection amount (command value) when the fuel increment control is not executed by a predetermined increment coefficient Kex (>1), thereby reducing the exhaust gas temperature THex. Similar to the increment coefficient Kcat, the increment coefficient Kex is also determined using variables such as the ignition retard angle Φ, the accelerator opening Acc, and the throttle valve opening θth. The exhaust gas temperature THex is detected by the exhaust gas temperature sensor 64, but an estimated value calculated from the intake air amount Qair corresponding to the engine load, the engine rotational speed Ne, etc. can also be used.

[0030] The shift control unit 76 executes shift control of the automatic transmission 18. Specifically, for example, shift determination is made based on the actual vehicle state using a shift map or the like stored in advance with variables such as the vehicle speed V and the accelerator opening Acc. And when it is determined that the automatic transmission 18 should be shifted, the automatic shift control of the automatic transmission 18 is executed so that the gear stage to be shifted is established. Specifically, a hydraulic control command signal Sp for engaging and / or releasing the engagement device involved in the shift of the automatic transmission 18 is output to the hydraulic control circuit 28 so that the determined gear stage is achieved.

[0031] Here, in order to appropriately advance the shift of the automatic transmission 18 by the shift control unit 76 (particularly, the power-on upshift), it is an effective method to execute shift torque down control for reducing the engine torque Te during the shift. Therefore, the electronic control device 70 functionally includes a torque down control unit 78 that executes shift torque down control so as to reduce the inertia torque during the inertia phase when the automatic transmission 18 is shifted by the shift control unit 76.

[0032] As the torque reduction control during gear shifting by the torque reduction control unit 78, an ignition retard method of retarding the ignition timing of the engine 12 by the ignition device 38 and a fuel cut method of stopping the fuel injection supplied to at least one cylinder of the engine 12 by the fuel injection device 36 are used. As the fuel cut method, the fuel supply by the fuel injection device 36 may be restricted by performing a closing control (also referred to as an electronic throttle valve closing control) of reducing the throttle valve opening θth of the electronic throttle valve 40. It is also possible to reduce the torque step by performing a short-time ignition retard immediately before restricting the fuel supply by the fuel cut method. Further, in the case of the fuel cut method, since the control accuracy and responsiveness of the intake air amount Qair are poor, the rise of the engine torque Te at the time of resuming the fuel supply after the torque reduction control during gear shifting becomes slow. Therefore, when using the fuel cut method, it is also possible to perform an opening control of the electronic throttle valve 40 while restricting the fuel supply. By performing the opening control of the electronic throttle valve 40 in this way, the cooling effect by the intake air can also be obtained.

[0033] FIG. 3 is a diagram showing a comparison of the features such as advantages and disadvantages of three methods: these ignition retard method, fuel cut method, and fuel cut method using the opening control of the electronic throttle valve 40 in combination. That is, in the ignition retard method, since the exhaust gas temperature THex rises, during high load operation such as sudden acceleration at start, when the catalyst temperature THcat reaches the overheat determination temperature THcath or the exhaust gas temperature THex reaches the overheat determination temperature THexh, and the fuel increment control by the overheat suppression control unit 74 is executed, there is a possibility that harmful gases such as HC and CO in the exhaust gas EX increase due to the fuel increment. On the other hand, in the fuel cut method, the control accuracy and responsiveness of the intake air amount Qair and the fuel injection amount are poor, and the power performance is impaired compared with the ignition retard method, such as the rise of the engine torque Te at the time of resuming the fuel supply after the torque reduction control during gear shifting becomes slow. In addition, since it becomes a lean atmosphere, the catalyst 44 may deteriorate at high temperatures.

[0034] The torque-down control unit 78 selects either the ignition retard method or the fuel cut method in accordance with steps S1 to S10 of the flowchart in FIG. 4 (hereinafter, the steps are omitted and simply referred to as S1 to S10), considering the features shown in FIG. 3, and executes torque-down control during gear shifting. In the flowchart of FIG. 4, YES in the decision step indicated by a diamond means affirmation, and NO means negation.

[0035] In S1 of FIG. 4, it is determined whether there is a request for torque-down control during gear shifting. That is, a request for torque-down control to reduce the engine torque Te is made to the torque-down control unit 78 during a power-on upshift of the automatic transmission 18 by the shift control unit 76 or the like. If there is no request for torque-down control during gear shifting, the process ends as it is, but if there is a request, S2 is executed. In S2, it is determined whether the catalyst temperature THcat representing the current temperature of the catalyst 44 is lower than a predetermined lean degradation temperature THcatd. The lean degradation temperature THcatd is the temperature at which there is concern about degradation of the catalyst 44 in a lean atmosphere when torque-down control during gear shifting is performed by the fuel cut method, and for example, a certain value is set in advance. If THcat < THcatd, S3 and subsequent steps are executed, but if THcat ≧ THcatd, the fuel cut method that results in a lean atmosphere is prohibited, and the ignition retard method is selected in S10 to execute torque-down control during gear shifting. In this case, when the catalyst temperature THcat rises and reaches the overheat determination temperature THcath, fuel increase control is executed by the overheat suppression control unit 74, and although harmful gases such as HC and CO in the exhaust gas EX may increase, it is possible to avoid degradation of the catalyst 44 due to a lean atmosphere as in the fuel cut method.

[0036] In S3, assuming a case where torque reduction control during gear shifting is performed using the ignition retard method, the temperature rise Δtcat of the catalyst temperature THcat and the temperature rise Δtex of the exhaust gas temperature Thex are calculated respectively. These temperature rises Δtcat and Δtex can be obtained based on the actual vehicle state using, for example, a map or the like that is predetermined with variables such as the engine rotational speed Ne, the intake air amount Qair, the ignition retard amount Φ, etc. In the next S4, the predicted temperature (THcat + Δtcat) is obtained by adding the temperature rise Δtcat to the current catalyst temperature THcat, and it is determined whether the predicted temperature (THcat + Δtcat) is lower than a predetermined upper limit temperature THcatmax. The upper limit temperature THcatmax is determined based on the overheat determination temperature THcath so that the execution of the fuel increment control by the overheat suppression control unit 74 is suppressed. For example, a temperature that is the same as the overheat determination temperature THcath or a predetermined temperature lower than that is set. And if (THcat + Δtcat) < THcatmax, S5 is executed, but if (THcat + Δtcat) ≧ THcatmax, the fuel cut method is selected in S8 and an opening control is performed to open the electronic throttle valve 40 by a predetermined opening degree in S9 to execute the torque reduction control during gear shifting. By using the fuel cut method in this way, it is possible to suppress the increase in harmful gases such as HC and CO in the exhaust gas EX, where the catalyst temperature THcat rises as in the ignition retard method and the fuel increment control is executed by the overheat suppression control unit 74.

[0037] In S5, a predicted temperature (THex + Δtex) is obtained by adding a temperature rise Δtex to the current exhaust gas temperature THex, and it is determined whether the predicted temperature (THex + Δtex) is lower than a predetermined upper limit temperature THexmax. The upper limit temperature THexmax is determined based on the overheat determination temperature THexh so that the execution of the fuel increment control by the overheat suppression control unit 74 is suppressed. For example, the same temperature as the overheat determination temperature THexh or a temperature lower than it by a predetermined temperature is set. If (THex + Δtex) < THexmax, S6 is executed. However, if (THex + Δtex) ≥ THexmax, the fuel cut method is selected in S8, and opening control is performed to open the electronic throttle valve 40 by a predetermined opening in S9 to execute the torque down control during gear shift. By using the fuel cut method in this way, it is possible to suppress the increase in the exhaust gas temperature THex as in the ignition retard method and the execution of the fuel increment control by the overheat suppression control unit 74, and the increase in harmful gases such as HC and CO is suppressed.

[0038] In S6, which is executed when both the determinations in S4 and S5 are YES, either the ignition retard method or the fuel cut method is selected. When the fuel cut method is selected, opening control is performed to open the electronic throttle valve 40 by a predetermined opening in S7 to execute the torque down control during gear shift. In S6, for example, it is configured to select either the ignition retard method or the fuel cut method based on the current driving state and driving conditions of the vehicle, the driving intention of the driver, etc. For example, when the driver can select a fuel economy priority mode or a sports mode, etc., in the fuel economy priority mode, the fuel cut method with excellent fuel economy may be selected, and in the sports mode, the ignition retard method with excellent power performance may be selected.

[0039] As described above, according to the torque-down control unit 78 of the vehicle 10 in this embodiment, when there is a request for torque-down control during gear shifting, the temperature of a predetermined portion of the exhaust pipe 34 of the engine 12 when torque-down control during gear shifting is performed using the ignition retard method is predicted. When the predicted temperatures (THcat + Δtcat) and (THex + Δtex) are equal to or higher than the predetermined upper limit temperatures THcatmax and THexmax [the determination in S4 or S5 is NO], the fuel cut method is selected in S8 to perform torque-down control during gear shifting. Therefore, by appropriately setting the upper limit temperatures THcatmax and THexmax, the execution frequency of the fuel increment control by the overheat suppression control unit 74 is reduced, and an increase in harmful gases such as HC and CO caused by the fuel increment can be suppressed. In this embodiment, since the upper limit temperatures THcatmax and THexmax are determined based on the overheat determination temperatures THcath and THexh of the overheat suppression control unit 74 so that the execution of the fuel increment control by the overheat suppression control unit 74 is suppressed, the effect of reducing the execution frequency of the fuel increment control and suppressing an increase in harmful gases such as HC and CO can be appropriately obtained.

[0040] Further, when performing torque-down control during gear shifting using the fuel cut method, since the electronic throttle valve 40 is opened and controlled while restricting fuel supply in S7 and S9, a predetermined intake air amount Qair is ensured even during torque-down control during gear shifting by the fuel cut method, and the engine torque Te can be quickly increased with the resumption of fuel supply after torque-down control during gear shifting, improving the response delay.

[0041] Also, when the current temperature THcat of the catalyst 44 is equal to or higher than the lean degradation temperature THcatd [the determination in S2 is NO], regardless of whether the predicted temperature (THcat + Δtcat) is equal to or higher than the upper limit temperature THcatmax, the ignition retard method is selected in S10 to perform torque-down control during gear shifting. Therefore, although there is a possibility that the fuel increment control is executed due to overheating, it is possible to avoid the deterioration of the catalyst 44 caused by the lean atmosphere as in the fuel cut method.

[0042] Further, the predicted temperature of the catalyst 44 (THcat + Δtcat) and the predicted temperature of the exhaust gas EX (THex + Δtex) are calculated respectively, and it is determined whether or not they are equal to or higher than the upper limit temperatures THcatmax and THexmax defined separately for the catalyst 44 and the exhaust gas EX. When either one of them is equal to or higher than the upper limit temperatures THcatmax and THexmax [the determination in S4 or S5 is NO], since the fuel cut method is selected in S8 and the torque down control during gear shift is implemented, the execution of the fuel increment control by the overheat suppression control unit 74 is appropriately suppressed.

[0043] In the implementation of the present invention, for example, as shown in the flowchart of FIG. 5, it is also possible to omit the steps S2, S7, S9, and S10.

[0044] As described above, the embodiments of the present invention have been described in detail based on the drawings, but this is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Signs

[0045] 10: Vehicle 12: Engine 18: Automatic Transmission 34: Exhaust Pipe 40: Electronic Throttle Valve 44: Catalyst 48: Turbocharger 70: Electronic Control Unit (Control Unit) 74: Overheat Suppression Control Unit 78: Torque Down Control Unit F: Fuel EX: Exhaust Gas THcat: Catalyst Temperature THcatd: Lean Deterioration Temperature THcat + Δtcat: Predicted Temperature THcatmax: Upper Limit Temperature THex: Exhaust Gas Temperature THex + Δtex: Predicted Temperature THexmax: Upper Limit Temperature

Claims

1. Regarding a vehicle comprising an engine and an automatic transmission that transmits power from the engine to the drive wheel side, In a control device for a vehicle, when performing shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply during shifting of the automatic transmission, When a request for the shift torque down control is made, predict the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method, When performing the shift torque down control using the fuel cut method, open and control the electronic throttle valve of the engine while restricting the fuel supply A control device for a vehicle, characterized in that.

2. Regarding a vehicle comprising an engine and an automatic transmission that transmits power from the engine to the drive wheel side, In a control device for a vehicle, when performing shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply during shifting of the automatic transmission, When a request for the shift torque down control is made, predict the temperature of a predetermined part of the exhaust pipe of the engine when using the ignition retard method, and when the predicted temperature of the predetermined part is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method, The temperature of the predetermined part is the temperature of a catalyst provided in the exhaust pipe, When the current temperature of the catalyst is equal to or higher than a predetermined lean degradation temperature at which catalyst degradation is a concern in the case of the fuel cut method, perform the shift torque down control using the ignition retard method regardless of whether the predicted temperature is equal to or higher than the upper limit temperature A control device for a vehicle, characterized in that.

3. Regarding a vehicle comprising an engine and an automatic transmission that transmits power from the engine to the drive wheel side, In a control device for a vehicle, when performing shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply during shifting of the automatic transmission, When a request for the shift torque down control is made, predict the temperature of a predetermined portion of the exhaust pipe of the engine when the ignition retard method is used, and when the predicted temperature of the predetermined portion is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method. The temperature of the predetermined portion is the temperature of a catalyst provided in the exhaust pipe and the temperature of the exhaust gas that rotates the turbine of a turbocharger provided in the engine. Calculate the predicted temperature of the catalyst and the predicted temperature of the exhaust gas, respectively, and determine whether or not these predicted temperatures are equal to or higher than the upper limit temperatures separately determined for the catalyst and the exhaust gas. When either one of them is equal to or higher than the upper limit temperature, perform the shift torque down control using the fuel cut method. A vehicle control device characterized by the above.

4. Regarding a vehicle equipped with an engine and an automatic transmission that transmits the power from the engine to the drive wheel side, In a vehicle control device that performs shift torque down control using either an ignition retard method of retarding the ignition timing of the engine or a fuel cut method of restricting fuel supply when the automatic transmission shifts gears, When a request for the shift torque down control is made, predict the temperature of a predetermined portion of the exhaust pipe of the engine when the ignition retard method is used, and when the predicted temperature of the predetermined portion is equal to or higher than a predetermined upper limit temperature, perform the shift torque down control using the fuel cut method. When the temperature of the predetermined portion of the exhaust pipe reaches a predetermined overheat determination temperature, the control device has an overheat suppression control unit that performs fuel increase control to increase the fuel supply amount to the engine in order to suppress overheating of the predetermined portion. The upper limit temperature is determined based on the overheat determination temperature so that the execution of the fuel increase control by the overheat suppression control unit is suppressed. A vehicle control device characterized by the above.

Images