WO2011007420A1

WO2011007420A1 - Control device for vehicle

Info

Publication number: WO2011007420A1
Application number: PCT/JP2009/062743
Authority: WO
Inventors: 光旗松下
Original assignee: トヨタ自動車株式会社
Priority date: 2009-07-14
Filing date: 2009-07-14
Publication date: 2011-01-20

Abstract

Provided is a control device for a vehicle capable of performing rapid torque down control and preventing a shock caused by a torque variation at that time. A control device for a vehicle which uses an internal combustion engine as a power source and can execute fuel cut is provided with a torque down controlling means for decreasing output torque of the internal combustion engine before the execution of the fuel cut (step S2) and a torque down rate changing means for changing the rate of decrease when the output torque is decreased by the torque down controlling means in a case where the output torque is close to zero including zero and in the other cases where the output torque is far from zero, relatively increasing the rate of decrease in the case where the output torque is far from zero, and relatively slowing the rate of decrease in the case where the output torque is close to zero (steps S3, S4).

Description

Vehicle control device

The present invention relates to an apparatus for controlling a vehicle that uses an internal combustion engine that outputs power by burning fuel such as a gasoline engine, and more particularly, for example, shock caused by torque fluctuation at the time of shifting or fuel cut. The present invention relates to a vehicle control device capable of executing torque down control for reducing the output torque of an internal combustion engine in order to prevent the occurrence of the engine.

In a vehicle that uses an internal combustion engine such as a gasoline engine as a power source, when the vehicle is traveling with inertial force, such as during deceleration with the accelerator off or coasting, the engine is forcibly driven by external force. Therefore, the rotation can be maintained without supplying fuel. Therefore, fuel consumption can be reduced and fuel consumption can be improved by temporarily stopping fuel supply to the engine during deceleration or coasting. This is a so-called fuel cut.

When the fuel cut for improving the fuel efficiency as described above is executed, the fuel supply is stopped, so that the operating state of the engine is forcibly rotated by the external force from the driving state where the power is output. Change to driven state. Therefore, the execution state of the fuel cut changes the operating state of the torque in the power transmission system, which may cause a shock or vibration, resulting in an uncomfortable feeling for the driver and the occupant. Such shocks and vibrations due to torque fluctuations in the power transmission system may occur at the time of shifting in an automatic transmission provided on the output side of the engine, for example, in addition to the above-described fuel cut. is there.

Therefore, in order to prevent shocks caused by torque fluctuations that occur during the execution of fuel cut as described above or during shifting with an automatic transmission, torque down control that intentionally reduces the output torque of the internal combustion engine is performed. It has been broken. For example, in the device described in Japanese Patent Application Laid-Open No. 8-246938, when performing fuel cut, the ignition timing for the air-fuel mixture in the combustion chamber of the internal combustion engine is retarded before the start of the fuel cut. The output torque is reduced.

Japanese Patent Laid-Open No. 2007-309218 discloses the ignition timing of an ignition plug provided in an engine for the purpose of preventing torque shock after returning from fuel cut and shortening unstable combustion time. An apparatus for controlling based on the above is described. The device described in Japanese Patent Application Laid-Open No. 2007-309218 delays the ignition timing when returning from the fuel cut at the time of deceleration, and the magnitude of the engine speed and the torque converter rotation speed after the return from the fuel cut. Is configured to estimate the reverse rotation timing at which the reverse rotation occurs and retard the ignition timing based on the reverse rotation timing.

Japanese Patent Laid-Open No. 2006-57527 discloses that the engine torque during engine operation based on the idle signal and the fuel cut signal is to reduce vehicle shock and vibration caused by engine electronic throttle control. An apparatus is described that is configured to gently change the throttle opening by limiting the change speed of the target throttle opening when it is determined that the direction of action is reversed.

Japanese Patent Application Laid-Open No. 7-293291 estimates the catalyst temperature according to the amount of fuel cut or ignition timing retard (retard) for the purpose of protecting the catalytic converter and the catalyst provided in the exhaust system of the vehicle. When the estimated value of the catalyst temperature reaches a predetermined set temperature, the apparatus is configured to change the engine output reduction pattern in a direction to reduce the unburned components in the exhaust gas introduced into the catalytic converter. Is described.

By delaying the ignition timing of the engine when performing fuel cut for improving fuel efficiency, as in the devices described in the above-mentioned JP-A-8-246938 and JP-A-2007-309218 The engine output torque can be reduced, that is, the engine torque down control can be executed. Therefore, it is possible to suppress the occurrence of a shock in the power transmission system caused by the engine operating state changing from the driving state to the driven state when the fuel cut is performed.

Such engine torque-down control is performed by, for example, retarding the ignition timing of the engine as in the devices described in the above-mentioned JP-A-8-246938 and JP-A-2007-309218. Alternatively, it can be executed by controlling the electronic throttle valve of the engine as in the device described in Japanese Patent Application Laid-Open No. 2006-57527. In particular, torque reduction by retarding the ignition timing of the engine is excellent in control responsiveness. Therefore, by executing the retard control of the ignition timing of the engine when performing the fuel cut as in the devices described in the above-mentioned Japanese Patent Application Laid-Open Nos. 8-246938 and 2007-309218. Further, the torque reduction control can be executed with good responsiveness, and the engine output torque can be quickly reduced. Therefore, the shock in the power transmission system accompanying the fuel cut can be appropriately prevented or suppressed.

At this time, the responsiveness of the deceleration operation can be further improved by further increasing the rate of decrease in the output torque of the engine when executing the torque down control. In addition, since the start time of the fuel cut that is executed after waiting for the engine output torque to decrease by a predetermined amount can be advanced, the fuel cut execution time can be lengthened accordingly, and as a result, fuel efficiency is improved by the fuel cut. The effect can be further enhanced. On the other hand, by performing a rapid torque-down control by increasing the rate of decrease of the output torque of the engine, there is a possibility that a shock in the power transmission system due to the sudden torque fluctuation may newly occur.

Thus, when executing engine torque-down control for reducing shocks in the power transmission system, it is possible to realize quick torque-down with good responsiveness and to reliably reduce shocks caused by torque fluctuations. There was still room for improvement in order to achieve both.

The present invention has been made paying attention to the above technical problem, and performs torque down control as quickly as possible, and prevents or suppresses shock caused by torque fluctuation during the torque down control. An object of the present invention is to provide a vehicle control device that can perform the above-described operation.

In order to achieve the above object, the present invention provides a vehicle control apparatus capable of executing fuel cut using an internal combustion engine as a power source and stopping or suppressing fuel supply to the internal combustion engine during traveling. Prior to the execution of the fuel cut, torque down control means for reducing the output torque of the internal combustion engine, and the rate of reduction when the output torque is reduced by the torque down control means are set as the output torque. When the output torque is far from 0, the rate of decrease is relatively increased, and the output torque is increased when the output torque is less than 0 including 0. A control device for a vehicle, comprising: torque down speed changing means for relatively slowing down the decrease speed when close to 0 A.

Further, according to the present invention, in the above invention, the torque down speed changing means sets, as the reduction speed, a first torque down speed that is relatively high when the output torque is far from the zero, When the output torque is close to 0, the vehicle control device includes means for setting a second torque down speed that is slower than the first torque down speed.

Further, the present invention is the above invention, wherein the internal combustion engine includes a spark ignition engine, and the torque down control means reduces the output torque by retarding an ignition timing of the spark ignition engine. It is a control device of vehicles including.

In the above invention, the present invention further comprises a catalytic converter provided in an exhaust system of the internal combustion engine, and a catalyst temperature detecting means for detecting a temperature of the catalyst of the catalytic converter, and the torque down control means However, when the temperature of the catalyst detected by the catalyst temperature detecting means is higher than a predetermined temperature determined in order to determine an overheated state of the catalyst, the vehicle control device includes means for suppressing the rate of decrease. It is.

The invention further includes a torque converter that receives the output torque, amplifies the output torque in accordance with a speed ratio between the input member and the output member, and outputs the torque. The changing means determines whether the output torque is far from the zero and the output torque is close to the zero based on the difference between the rotational speed of the output shaft of the internal combustion engine and the rotational speed of the output member. A vehicle control apparatus including means.

On the other hand, according to the present invention, in a vehicle control apparatus using an internal combustion engine as a power source, a torque down control means for reducing the output torque of the internal combustion engine, and a reduction speed when the output torque is reduced by the torque down control means In the case where the output torque is close to 0 including 0 and the case where the output torque is far from 0, and when the output torque is far from 0, the decrease speed is relatively increased, When the output torque is close to 0, the vehicle control apparatus includes torque down speed changing means for relatively slowing down the decrease speed.

According to the present invention, in order to prevent a shock caused by a fluctuation in torque at the time of executing the fuel cut, torque down control for reducing the output torque of the internal combustion engine is executed prior to the execution of the fuel cut. The In this case, if the output torque to be reduced is still far from 0, the output torque can be quickly reduced at a fast reduction speed. When the output torque becomes close to 0, the output torque is gradually reduced at a slow decrease rate. Therefore, when the vehicle reverses from the driving state to the driven state in the vicinity where the output torque becomes zero, it is possible to prevent or suppress a shock or vibration caused by a sudden torque fluctuation or a large torque fluctuation amount. .

Since the output torque can be rapidly reduced until the output torque reaches near zero, the time required to reach the desired torque reduction amount is shortened as much as possible, and the fuel cut is started accordingly. You can expedite. As a result, the fuel cut execution time can be lengthened, and the fuel efficiency improvement effect by the fuel cut can be enhanced.

Further, according to the present invention, when the torque down control is executed, if the output torque to be reduced is still far from 0, the output torque can be quickly reduced at the first torque down speed that is relatively fast. . When the output torque becomes close to 0, the output torque is gradually reduced at the second torque down speed that is slower than the first torque down speed. Therefore, it is possible to reliably reduce the rate of decrease of the output torque in the vicinity where the output torque becomes zero.

Further, according to the present invention, when the internal combustion engine is a spark ignition engine such as a gasoline engine, the torque reduction control of the internal combustion engine is easily executed by retarding the ignition timing of the spark ignition engine. be able to. For example, by controlling the retard amount and retard speed of the ignition timing, the torque down amount and the decrease speed of the torque down control can be easily controlled.

Further, according to the present invention, when the temperature of the catalyst used in the exhaust system of the internal combustion engine is high, the rate of decrease when the torque down control is executed is suppressed. Rapid retarding control is accompanied by a rise in the exhaust temperature of the internal combustion engine, which causes a catalyst temperature rise. Therefore, when the catalyst is at a high temperature, the rate of decrease in torque-down control is suppressed, that is, the retard amount or retard speed of retard control is suppressed, thereby preventing the catalyst from overheating and protecting the catalyst. be able to.

According to this invention, for example, when a torque converter that amplifies and transmits the output torque of the internal combustion engine is provided in a power transmission mechanism such as a transmission, the rotational speed of the output shaft of the internal combustion engine and the torque converter By obtaining the difference from the rotation speed of the output member, it is possible to easily determine whether the output torque that is reduced by the torque-down control is far from 0 or close to 0.

On the other hand, according to the present invention, when executing the torque down control for reducing the output torque of the internal combustion engine, if the output torque to be reduced is still far from 0, the output torque can be quickly reduced at a fast reduction speed. When the output torque becomes close to 0, the output torque is gradually reduced at a slow decrease rate. Therefore, when the vehicle reverses from the driving state to the driven state in the vicinity where the output torque becomes zero, it is possible to prevent or suppress a shock or vibration caused by a sudden torque fluctuation or a large torque fluctuation amount. .

It is a flowchart for demonstrating the example of control in the control apparatus of the vehicle of this invention. It is a time chart which shows the behavior of each part at the time of performing control in the control apparatus of vehicles of this invention. It is a time chart which shows the behavior of each part at the time of performing other control in the control apparatus of the vehicle of this invention. It is a schematic diagram for demonstrating the structure of the vehicle made into the object of control by this invention.

Next, the present invention will be described based on specific examples. FIG. 4 shows the configuration of the drive system and control system of the vehicle Ve to be controlled in the present invention. In FIG. 4, reference numeral 1 denotes a power source 1 of the vehicle Ve. In the present invention, an internal combustion engine that is a power device that burns fuel and outputs power is targeted. In the following description, the power source 1, that is, the internal combustion engine 1 is referred to as an engine (ENG) 1.

An automatic transmission (AT) 3 is connected to the output side of the engine 1 via a torque converter 2. Drive wheels 7 are connected to the output side of the automatic transmission 3 via, for example, a propeller shaft 4, a differential 5, a drive shaft 6, and the like. That is, the output shaft 1a of the engine is connected to a pump impeller 2a that is an input member of the torque converter 2. A turbine runner 2 b that is an output member of the torque converter 2 is connected to the input shaft 3 a of the automatic transmission 3. Therefore, the output torque of the engine 1 is input to the automatic transmission 3 via the torque converter 2, and is shifted according to the gear ratio set in the automatic transmission 3, and transmitted as drive torque to the drive wheel 7 side. It has come to be.

As described above, the engine 1 is an internal combustion engine. In particular, in this embodiment, the engine 1 is a spark ignition engine such as a gasoline engine, an LPG engine, or an alcohol fuel engine. The engine 1 is configured to be able to electrically control operating conditions such as throttle opening (intake amount), fuel injection amount (fuel supply amount), intake / exhaust valve opening / closing operation, ignition timing, and the like.

Further, the exhaust system of the engine 1 is provided with a catalytic converter 8 having an exhaust purification catalyst 8a. A catalyst temperature sensor 9 for detecting the temperature of the catalyst 8a in the catalytic converter 8 is provided.

The torque converter 2 has a conventionally known configuration, and applies a spiral flow of oil generated by the pump impeller 2a to the turbine runner 2b to rotate the turbine runner 2b, and from the turbine runner 2b to the pump impeller 2a. The flow direction of the oil returning to is controlled by a stator (not shown), and torque is transmitted through the oil.

Further, the torque converter 2 is provided with a lock-up clutch 2c. The lock-up clutch 2c is provided between an input-side member to which the pump impeller 2a is connected and an output-side member to which the turbine runner 2b is connected. The input element and the output element are mechanically coupled to each other by a frictional force or the like. And is configured to transmit torque.

The automatic transmission 3 is a so-called electronically controlled transmission that performs shift control that changes the gear ratio by electrically controlling the hydraulic pressure, for example, and is, for example, a hydraulic control device (integrated in the automatic transmission 3 ( (Not shown) is configured to switch or change the gear position or gear ratio. As this automatic transmission 3, a transmission of various mechanisms such as a stepped automatic transmission or a belt-type or toroidal-type continuously variable transmission can be used.

The operation state of the engine 1 such as the throttle opening, the fuel injection amount, the intake / exhaust valve opening / closing operation, and the ignition timing, and the operation of the hydraulic control device and the actuator for executing the shift control of the automatic transmission 3 are performed. An electronic control unit (ECU) 10 for controlling the state is provided.

As an example, the electronic control device 10 is composed of a central processing unit, a storage device, and a microcomputer mainly including an input / output interface. The electronic control unit 10 includes, for example, an engine speed sensor 11 that detects the speed of the output shaft 1a of the engine 1, a turbine speed sensor 12 that detects the speed of the turbine runner 2b of the torque converter 2, and an accelerator pedal. An accelerator sensor (or an accelerator switch) 13 for detecting an operating state or an operation amount, a brake sensor (or a brake switch) 14 for detecting an operating state or an operation amount of a brake pedal, a wheel speed sensor 15 for detecting a vehicle speed, or the like. The output signal is input.

From the electronic control unit 10, the control signal for controlling the throttle opening of the engine 1, the fuel injection amount, the intake / exhaust valve opening / closing operation, the ignition timing, or the like, or the engagement of the lock-up clutch 2 c of the torque converter 2. A control signal for controlling the releasing operation or a control signal for controlling the shifting operation of the automatic transmission 3 is output. Therefore, the control device for the vehicle Ve in the present invention is based on the control signal calculated and output by the electronic control device 10, and the operation control of the engine 1, the engagement control of the lockup clutch 2c, and the shift of the automatic transmission 3 are performed. It is configured to execute control and the like.

In particular, regarding the operation control of the engine 1, in order to reduce fuel consumption and improve fuel efficiency when the vehicle Ve is decelerating or coasting, for example, when the vehicle 1 is decelerating or coasting, the engine 1 is warmed up. Preconditions for starting the control are that it has been completed, that the engine 1 has a rotational speed equal to or higher than a predetermined speed, that the throttle opening is closed to about the idle opening, and that the accelerator pedal is returned. In the case where all of them are established, a so-called fuel cut can be executed that temporarily stops or suppresses the fuel supply to the engine 1.

Further, by controlling the throttle opening of the engine 1 or the ignition timing, it is possible to execute torque down control for intentionally or forcibly reducing the output torque of the engine 1. In particular, the torque down control by retarding the ignition timing of the engine 1 has good control responsiveness, and the output torque of the engine 1 in the torque down control is controlled by controlling the retard amount and retard speed of the ignition timing. The amount of decrease or the rate of decrease can be easily controlled.

As described above, the present invention aims to execute torque reduction as quickly as possible, and to prevent or suppress shock caused by torque fluctuation at the time of torque reduction. The control device is configured to execute the following control.

FIG. 1 is a flowchart for explaining an example of control by the control device of the present invention, and the routine shown in this flowchart is repeatedly executed every predetermined short time. In the flowchart of FIG. 1, first, it is determined whether or not the driver has performed an accelerator-off operation (step S1). Specifically, it is determined whether or not the detected value of the accelerator switch 13 has been switched from ON to OFF, that is, whether or not an operation for returning the accelerator pedal that the driver has depressed has been performed based on a deceleration request or the like.

If the driver does not perform the accelerator-off operation, that is, the detected value of the accelerator switch 13 has not been switched from ON to OFF, and if the determination is negative in this step S1, the fuel efficiency is improved. Since this fuel cut is not executed, this routine is temporarily terminated without executing the subsequent control.

On the other hand, if the driver makes an accelerator-off operation, that is, if the detected value of the accelerator switch 13 is switched from ON to OFF, and if the determination in step S1 is affirmative, step S2 Then, prior to the fuel cut scheduled to be executed in the future, torque-down control for reducing the output torque of the engine 1 is executed. At the beginning of this torque-down control, the output torque of the engine 1 is reduced as rapidly as possible under the first torque-down speed that is relatively high.

The torque down control in the present invention is executed by retarding the ignition timing of the engine 1, for example. Specifically, by controlling the retard amount when retarding the ignition timing of the engine 1, the torque down amount of the torque down control, that is, the decrease amount of the output torque of the engine 1 is controlled. Further, by controlling the retarding speed at which the ignition timing of the engine 1 is retarded, the torque down speed of the torque down control, that is, the output torque decreasing speed of the engine 1 is controlled. Therefore, the first torque down speed can be set by retarding the ignition timing of the engine 1 at a predetermined retard speed with a relatively fast change speed.

When a fuel cut for improving fuel efficiency is executed when the accelerator pedal is released during traveling, the fuel supply to the engine 1 is stopped while the vehicle Ve is coasting, so the engine 1 Since the combustion is not performed at this point, the output torque of the engine 1 becomes zero. When the output torque of the engine 1 becomes 0, the vehicle Ve is driven by an external force such as an inertial force or gravity of the vehicle Ve from a driving state where the driving force has been generated by the output torque of the engine 1 until then. Switch to When the vehicle Ve is switched from the driving state to the driven state, the torque transmission direction in the power transmission path from the engine 1 to the driving wheel 7 is switched. That is, from the state in which the output torque of the engine 1 is transmitted from the engine 1 to the drive wheels 7 via the torque converter 2, the automatic transmission 3 and the differential 5, the torque of the drive wheels 7 is The state changes from the drive wheel 7 to the engine 1 via the differential 5, the automatic transmission 3, the torque converter 2, and the like.

The engine 1, the automatic transmission 3, the differential 5, and the like use gear mechanisms for transmitting power, and these gear mechanisms inevitably have backlash between the tooth surfaces of the gear pairs that mesh with each other. Exists. Therefore, when the torque transmission direction is switched as described above, the working tooth surface of the gear involved in power transmission changes. That is, the meshing side tooth surface and the non-meshing side tooth surface of the gear are interchanged. Therefore, if the torque fluctuation when the output torque of the engine 1 becomes zero and the torque transmission direction is switched is large, the impact when the working tooth surface changes during the backlash of the gear mechanism increases, and the vehicle Ve is operated. There is a possibility of giving a shock or discomfort to the passenger or passenger.

Therefore, when the fuel cut is executed, the torque reduction control of the engine 1 is executed prior to the start of the fuel cut. That is, the output torque of the engine 1 is reduced in advance before the start of fuel cut. Therefore, the torque fluctuation at the time of executing the fuel cut can be made as small as possible, and the occurrence of a shock due to the torque fluctuation accompanying the execution of the fuel cut can be prevented or suppressed.

When torque-down control for preventing a shock at the time of fuel cut is started, the drive system from the engine 1 to the drive wheel 7 changes from the drive state in which the engine 1 outputs torque as described above to the drive wheel. It is determined whether or not it is just before reversing to the driven state where torque is input from 7 (step S3). Immediately before the drive system is reversed from the drive state to the driven state is a time when the output torque of the engine 1 to be reduced becomes close to 0, for example, preset from the time when the output torque of the engine 1 becomes 0 This is a point in time before the predetermined time, or a point in time when the output torque of the engine 1 drops to a value that is larger than 0 by a predetermined torque set in advance.

Therefore, in this step S3, first, when the output torque of the engine 1 is reduced by the torque-down control, the time point when the torque becomes 0 is estimated and obtained. For example, the rotational speed (engine rotational speed) Ne of the output shaft 1a of the engine 1 and the rotational speed (turbine rotational speed) Nt of the turbine runner 2b of the torque converter 2 are detected, and these engine rotational speed Ne and turbine rotational speed Nt are detected. Can be obtained by predicting the time point when the difference between them becomes zero. That is, the time when the difference between the engine speed Ne and the turbine speed Nt becomes 0 can be estimated as the time when the output torque of the engine 1 becomes 0.

When the time point at which the output torque of the engine 1 becomes 0 is estimated, the time point before the time point, or the time point when the output torque of the engine 1 decreases to a value larger than 0 by a predetermined torque is the above drive. It is obtained as the time immediately before the system is reversed from the driving state to the driven state. For example, it can be obtained by calculating a time before a predetermined time set in advance with respect to the time when the output torque of the engine 1 estimated as described above becomes zero. Alternatively, it can be obtained by calculating the time when the output torque of the engine 1 that has been reduced reaches a predetermined torque set in advance as a value larger than zero. Alternatively, the time when the difference between the engine speed Ne and the turbine speed Nt is equal to or less than a predetermined value set as a threshold value can be set as the time immediately before the drive system is reversed from the drive state to the driven state. .

If it is not determined in this step S3 that the drive system is not immediately before the drive state is reversed from the drive state to the driven state, the control in step S3 is executed again. That is, the control in step S3 is repeatedly executed until the time point immediately before the drive system is reversed from the drive state to the driven state is reached.

On the other hand, if the determination is affirmative in step S3 due to the fact that the drive system is just before reversing from the drive state to the driven state, the process proceeds to step S4 and the output of the engine 1 in the torque-down control. The torque reduction speed is changed from the first torque down speed set at the beginning of the torque down control to the second torque down speed that is slower than the first torque down speed. That is, at the time immediately before the drive system reverses from the drive state to the driven state, the decrease rate of the torque down control is reduced. This reduction in the decrease speed is continued until the fuel cut start point described later. Therefore, in the period from the time immediately before the drive system reverses from the drive state to the driven state until the output torque of the engine 1 becomes close to 0, the rate of decrease in the torque down control is reduced. The torque is gradually reduced.

The change in the decrease speed of the torque-down control in step S4 is specifically performed by controlling the retard speed when retarding the ignition timing of the engine 1 as described above. That is, the second torque down speed is set by retarding the ignition timing of the engine 1 at a predetermined retard speed that is slower than the first torque down speed.

Further, when the second torque down speed is set as described above, for example, by considering the engine speed Ne and the turbine speed Nt detected when the torque reversal point is estimated, 2 Torque down speed can be set appropriately. Specifically, when the second torque down speed is set, a differential value of the difference between the detected engine speed Ne and the turbine speed Nt is calculated, and the magnitude of the differential value, that is, the engine speed Ne. A second torque down speed is set based on the decreasing speed. For example, when the differential value is large, that is, when the decrease speed of the engine speed Ne is fast, the second torque down speed is set to a slower value. Alternatively, the arrival time from the current time until the output torque of the engine 1 becomes zero is estimated from the difference between the current engine speed Ne and the turbine speed Nt and the differential value of the difference, Accordingly, the second torque down speed is appropriately set.

As in the case where the fuel cut is performed, that is, for the same reason that a shock may occur when the vehicle Ve is reversed from the driven state to the driven state by executing the fuel cut, the torque is When the output torque of the engine 1 becomes 0 by executing the down control, the torque transmission direction is reversed, and if the torque fluctuation at that time is large, the driver or the occupant of the vehicle Ve is given a shock or discomfort. There was a possibility.

On the other hand, as described above, the output torque of the engine 1 gradually decreases in the period from the time immediately before the drive system is reversed from the drive state to the driven state until the time when the output torque of the engine 1 becomes zero. By doing so, it is possible to prevent or suppress the occurrence of a shock due to a large or abrupt torque fluctuation when the torque transmission direction is reversed in accordance with the execution of the torque down control.

Then, the fuel cut of the engine 1 is started after the decrease speed of the torque-down control is decelerated immediately before the drive system is reversed from the drive state to the driven state (step S5). Thereafter, this routine is once terminated.

The behavior of each part of the vehicle Ve when the above control example is executed is shown in the time chart of FIG. When the accelerator-off operation is performed at time t0, the engine speed Ne starts to decrease accordingly, and a preparation stage for executing fuel cut is entered. Subsequently, torque-down control for suppressing torque fluctuation when executing the fuel cut is started. That is, the retard control of the ignition timing of the engine 1 is started (time t1). At that time, during the period from the time t1 when the retard control is started to the time t2 set as the time immediately before the drive system is reversed from the drive state to the driven state, the first torque reduction with a relatively fast retard speed is performed. Delay angle control is executed at speed. After time t2, the retard control is executed at the second torque down speed that is slower than the first torque down speed.

The time t3 when the difference between the engine speed Ne and the turbine speed Nt becomes 0 is estimated and set as the time when the output torque of the engine 1 becomes 0 as described above. The fuel cut is started when the output torque of the engine 1 is reduced to a desired value by the retard control (time t4). Further, the retard control is terminated with the start of the fuel cut. That is, the ignition timing of the engine 1 is returned to the normal state.

Further, the time t2, that is, the time immediately before the drive system is reversed from the drive state to the driven state, can be set, for example, as the time when the output torque of the engine 1 drops to a predetermined torque larger than 0 set in advance as a threshold value. it can. Alternatively, as shown in FIG. 2, the time t3 can be set as the time t2, which is a time that is a predetermined time Δt later than the time t3, that is, when the output torque of the engine 1 becomes zero. Alternatively, a time when the difference between the engine speed Ne and the turbine speed Nt is equal to or less than a predetermined value ΔN set in advance can be set as the time t2.

FIG. 3 shows the behavior of each part of the vehicle Ve when another control example by the control device of the present invention is executed. The control example shown in the time chart of FIG. 3 takes into account the temperature of the catalyst 8a in the catalytic converter 8 provided in the exhaust system of the engine 1 when executing the retard control of the engine for torque down control. This is an example of control.

As described above, when the ignition timing is retarded, the exhaust temperature of the engine 1 rises and the heat load on the exhaust system increases. Therefore, if rapid or large retardation control is performed, the catalyst 8a in the exhaust system may be overheated. Therefore, in the present invention, the temperature of the catalyst 8a is detected by the catalyst temperature sensor 9 provided in the catalytic converter 8 as the catalyst temperature detecting means, and the temperature of the catalyst 8a is determined in advance in order to determine the overheated state of the catalyst 8a. When reaching a predetermined temperature as a predetermined temperature, ie, a threshold temperature for preventing damage due to overheating of the catalyst 8a, the retard speed or retard amount when executing the retard control is suppressed.

Specifically, when the temperature of the catalyst 8a is a high temperature that is equal to or higher than a predetermined temperature, as shown in FIG. 3, the retarding speed in the retarding control during the period from the starting point t1 of the retarding control to the time t2 is as shown in FIG. Is suppressed so as to be slower than the normal retardation angle speed indicated by the broken line. That is, the rate of decrease in the torque down control of the engine 1 by the retard control (in this case, the first torque down speed) is suppressed.

As the catalyst temperature detecting means for detecting the temperature of the catalyst 8a, in addition to the catalyst temperature sensor 9 for directly detecting the temperature of the catalyst 8a as described above, for example, the output torque of the engine 1, the throttle opening degree, It is also possible to detect a control amount that affects the increase or decrease in the load of the engine 1, such as the intake air amount or the vehicle speed, and estimate the exhaust temperature of the engine 1 and the temperature of the catalyst 8a based on the detected values.

Here, the relationship between the above-described specific example and the present invention will be briefly described. In the flowchart shown in FIG. 1, the functional means for executing step S2 corresponds to the torque-down control means in the present invention. , S4 corresponds to the torque down speed changing means in the present invention.

As described above, according to the vehicle control device of the present invention, the output of the engine 1 is executed prior to the execution of the fuel cut in order to prevent a shock caused by the fluctuation of the torque when the fuel cut is executed. Torque down control for reducing the torque is executed. In this case, the time point t3 that becomes a change point when the output torque of the engine 1 becomes 0 due to torque reduction, that is, when the engine 1 is reversed from the driving state in which the torque is output to the driven state driven by the external force is set. Inferred and required. Then, the time t2, which is a time before the time t3, or a time when the output torque to be reduced reaches a value larger than 0 by a predetermined torque, is reversed from the driving state to the driven state. The torque-down control is executed at the first torque-down speed at which the decrease speed is high during the period before the time t2 with the time t2 as a boundary. In a period after time t2, torque down control is executed at a second torque down speed that is slower than the first torque down speed.

Therefore, when the torque reduction control is executed in combination with the fuel cut, the output torque is rapidly reduced at a rapid reduction rate until time t2 that is a predetermined time Δt before the time t3 when the output torque of the engine 1 becomes zero. Immediately before reaching the time point t3 when the output torque of the engine 1 becomes 0 after the time t2 has elapsed, the output torque can be gradually reduced at a slow decrease rate. Therefore, when the vehicle reverses from the driving state to the driven state in the vicinity of the time point t3 when the output torque of the engine 1 becomes 0, a shock or vibration caused by a large torque fluctuation amount or a sudden torque fluctuation is prevented. Or it can be suppressed.

And since the output torque can be rapidly reduced until just before the drive system reverses from the drive state to the driven state, the time to reach the desired torque reduction amount is reduced as much as possible, The start of the fuel cut can be accelerated accordingly. As a result, the execution time of the fuel cut can be lengthened, and the fuel efficiency improvement effect by the fuel cut can be further enhanced.

Moreover, if the engine 1 is a spark ignition engine such as a gasoline engine as in the above-described example, the torque reduction control as described above can be easily executed by retarding the ignition timing of the engine 1. Can do. That is, by controlling the retard amount and retard speed of the ignition timing, it is possible to easily control the torque down amount and the decrease speed of the torque down control.

Further, when the temperature of the catalyst 8a used in the exhaust system of the engine 1 is high, the rate of decrease in torque down control is suppressed. That is, the retard speed or retard amount of the retard control is suppressed. Therefore, when the catalyst 8a is at a high temperature, it is possible to prevent overheating of the catalyst 8a due to rapid retard control and protect the catalyst 8a.

Note that the present invention is not limited to the specific examples described above. That is, in the specific example described above, an example in which torque down control of the engine 1 is executed in order to prevent a shock caused by torque fluctuation at the time of fuel cut is described. Is not limited to the control executed at the time of fuel cut. For example, when the purpose is to suppress torque fluctuations during shifting of an automatic transmission or when the purpose is to suppress torque fluctuations during operation of a lockup clutch of a torque converter, The object of the present invention is torque down control that is executed when the purpose is to suppress torque fluctuations that occur in the power transmission system from the power source to the drive wheels.

Claims

In a control apparatus for a vehicle capable of executing fuel cut using an internal combustion engine as a power source and stopping or suppressing fuel supply to the internal combustion engine during traveling,
Torque down control means for reducing the output torque of the internal combustion engine prior to the execution of the fuel cut when the fuel cut is executed;
A means for changing a reduction speed when the output torque is reduced by the torque-down control means between a case where the output torque is close to 0 including 0 and a case where the output torque is far from 0. Torque down speed changing means for relatively decreasing the decreasing speed when the distance from the distance is 0 and relatively decreasing the decreasing speed when the output torque is close to 0. Vehicle control device.
The torque down speed changing means sets the first torque down speed that is relatively high when the output torque is far from the zero as the reduction speed, and the torque down speed changing means when the output torque is close to the zero. The vehicle control device according to claim 1, further comprising means for setting a second torque down speed that is slower than the first torque down speed.
The internal combustion engine includes a spark ignition engine,
3. The vehicle control device according to claim 1, wherein the torque down control means includes means for reducing the output torque by retarding an ignition timing of the spark ignition engine.
A catalytic converter provided in an exhaust system of the internal combustion engine;
Further comprising catalyst temperature detection means for detecting the temperature of the catalyst of the catalytic converter,
The torque-down control means includes means for suppressing the rate of decrease when the temperature of the catalyst detected by the catalyst temperature detection means is higher than a predetermined temperature that is determined in advance to determine an overheated state of the catalyst. The vehicle control device according to any one of claims 1 to 3.
A torque converter that receives the output torque, amplifies the output torque according to a speed ratio between the input member and the output member, and outputs the amplified torque;
When the output torque is far from 0 and the output torque is close to 0 based on the difference between the rotational speed of the output shaft of the internal combustion engine and the rotational speed of the output member. The vehicle control device according to claim 1, further comprising means for determining
In a vehicle control apparatus using an internal combustion engine as a power source,
Torque down control means for reducing the output torque of the internal combustion engine;
A means for changing a reduction speed when the output torque is reduced by the torque-down control means between a case where the output torque is close to 0 including 0 and a case where the output torque is far from 0. Torque down speed changing means for relatively decreasing the decreasing speed when the distance from the distance is 0 and relatively decreasing the decreasing speed when the output torque is close to 0. Vehicle control device.
The torque down speed changing means sets the first torque down speed that is relatively high when the output torque is far from the zero as the reduction speed, and the torque down speed changing means when the output torque is close to the zero. The vehicle control device according to claim 6, further comprising means for setting a second torque down speed that is slower than the first torque down speed.
The internal combustion engine includes a spark ignition engine,
8. The vehicle control device according to claim 6, wherein the torque down control means includes means for reducing the output torque by retarding an ignition timing of the spark ignition engine.
A catalytic converter provided in an exhaust system of the internal combustion engine;
Further comprising catalyst temperature detection means for detecting the temperature of the catalyst of the catalytic converter,
The torque-down control means includes means for suppressing the rate of decrease when the temperature of the catalyst detected by the catalyst temperature detection means is higher than a predetermined temperature that is determined in advance to determine an overheated state of the catalyst. The vehicle control device according to any one of claims 6 to 8.
A torque converter that receives the output torque, amplifies the output torque according to a speed ratio between the input member and the output member, and outputs the amplified torque;
When the output torque is far from 0 and the output torque is close to 0 based on the difference between the rotational speed of the output shaft of the internal combustion engine and the rotational speed of the output member. The vehicle control device according to claim 6, further comprising means for determining