JP2008045446A - Control device for vehicle equipped with internal combustion engine executing fuel cut control and stepped automatic transmission, program materializing method thereof, and record medium recording program thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover from fuel cut with avoiding a shock in a vehicle equipped with an automatic transmission capable of varying speed change point according to deceleration. <P>SOLUTION: In this control device for the vehicle, ECU executes a program keeping a flag which is a premise of fuel cut under an on-condition by performing slip control of a lock-up clutch during deceleration (S2900), and continues fuel cut not to make recovery from fuel cut overlap with speed change period if down shift command is issued (Yes in S2400) when fuel cut natural recovery conditions are not satisfied (No in S2200). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to control of a vehicle equipped with an internal combustion engine that performs fuel cut control and a stepped automatic transmission, and more particularly to a vehicle that changes downshift timing to achieve a desired deceleration. The present invention relates to control of a vehicle that avoids a shock when returning from a fuel cut and at the time of shifting.

  In a vehicle equipped with an automatic transmission, an impact is caused by temporary torque fluctuations that occur during gear shifting. For example, in a downshift caused by slow deceleration, there is almost no change in the vehicle speed with an increase in the transmission gear ratio. Therefore, when the engine output shaft and the vehicle drive shaft are connected during a shift, the inertia mass of the drive shaft is reduced. The engine speed increases rapidly under the influence. This rapid increase in engine speed consumes the torque of the inertial mass of the drive shaft, and temporarily reduces the drive torque of the vehicle. This temporary fluctuation of the drive torque may be felt as an unpleasant impact by the occupant. Not only for these causes, but in the case of automatic transmissions unlike manual transmissions, the driver feels shock because the transmission of the driving force is temporarily interrupted at the time of shifting under conditions that the driver does not recognize. Sometimes.

  By the way, since the engine output (hereinafter, the engine output may be used synonymously with the engine torque) is not required for the deceleration traveling, it depends on the operation state such as the deceleration state, the engine speed, and the engine cooling water temperature. Thus, fuel cut control is performed to stop fuel supply to the engine when the vehicle is decelerating, thereby improving fuel efficiency by reducing fuel consumption. This fuel cut control is a control that improves fuel efficiency by reducing the supply of fuel to the engine as much as possible within a range that does not impair driving performance and riding comfort. In general, the supply of fuel is stopped when the engine speed falls within a predetermined range (more than the fuel cut speed) during deceleration while the engine is idling. Specifically, if the throttle valve is closed during traveling (decelerated traveling) and the engine speed is equal to or higher than the fuel cut speed, the fuel supply is stopped. Further, when the engine speed decreases and reaches the return speed (fuel cut return speed) that defines the lower limit of the range, the fuel supply is resumed. In recent years, in order to prolong the fuel cut control, the lockup clutch may be engaged or slipped to delay the decrease in the engine speed and further improve fuel efficiency.

  JP-A-1-247733 (Patent Document 1) discloses a case where a shift (downshift) that increases a transmission gear ratio is performed in a vehicle having an automatic transmission when fuel cut control is executed. The control device which avoids the impact given to a passenger is disclosed. The control device includes an automatic transmission, an engine including a fuel cut control unit that stops fuel supply when decelerating and a fully closed air amount control unit that controls an intake air amount when the throttle is fully closed. A downshift determination unit that detects a downshift by detecting a position is provided. When a downshift is detected, the total closed air amount is increased after a predetermined time T (2) that matches the characteristics of the total closed air amount control unit. In addition, if the fuel cut control is being performed, the fuel cut is stopped after a predetermined time T (1) suitable for the characteristics of the fuel cut control unit after detecting the downshift.

  According to this control device, the fuel cut control is stopped at the time of downshift and the air volume is increased, and a delay time is provided from the detection of the downshift to the start of the corresponding operation so as to match each characteristic. It was. As a result, when a downshift is detected, the fuel cut is stopped and the engine brake torque is reduced. In addition, the engine brake torque is reduced by avoiding the air amount being too small, and the impact is reduced. The effect of relieving is expressed. Thereby, the effect that the shock at the time of downshift can be reduced further is acquired.

  Thus, in a vehicle that performs fuel cut control, detection of a shift point (hereinafter referred to as a shift point) is essential in order to avoid an impact at the timing of a downshift. Japanese Patent Application Laid-Open No. 11-257482 (Patent Document 2) describes an excessive engine generated by executing a downshift in a coast state (a state where power is transmitted from a wheel side to an engine side: a driven state). Disclosed is a shift control device for an automatic transmission that avoids an increase in occurrence of shift shock caused by braking force. This shift control device for an automatic transmission is a shift control device for an automatic transmission that includes a plurality of clutches and performs downshift of clutch-to-clutch shift according to a shift point during coasting, and detects a vehicle deceleration. And changing the shift point when performing a downshift during coasting according to the deceleration of the vehicle.

According to this shift control device for an automatic transmission, by changing the shift point according to the deceleration of the vehicle, it is not necessary to set the shift point higher than necessary, thereby suppressing excessive engine braking during deceleration. The shift shock can be suppressed and a good downshift can be executed at any deceleration.
JP-A-1-247733 Japanese Patent Laid-Open No. 11-257482

  In recent automatic transmissions, the trend of multi-stage (7th to 9th speeds) is progressing for the purpose of further improving fuel efficiency and drivability. As the number of shift gears increases, as disclosed in Patent Document 2, when the shift point is changed according to the deceleration, the fuel cut return timing and the shift are changed as compared with the case where the shift point is constant. There is a high possibility that the point (shift timing) overlaps.

  However, in any of the above-mentioned patent documents, there is no mention of the occurrence of a shock due to the overlap between the fuel cut return timing and the shift timing on the premise that the shift point is changed in accordance with the deceleration.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an automatic transmission that varies a shift point according to deceleration and a vehicle equipped with an internal combustion engine that executes fuel cut control. The present invention provides a vehicle control device, a control method, a program for realizing the method, and a recording medium on which the program is recorded, which avoids a shift shock and a fuel cut return shock.

  According to a first aspect of the present invention, there is provided a vehicle control apparatus that controls a vehicle including an internal combustion engine that executes fuel cut control and a stepped automatic transmission. The control device executes a fuel cut that stops the fuel supply to the internal combustion engine when the vehicle condition satisfies a predetermined execution condition, and a change means for changing a downshift point at the time of deceleration. The fuel cut execution means for controlling the internal combustion engine and the downshift speed change period executed on the basis of the downshift speed change point so as to return from the fuel cut when the state satisfies a predetermined return condition. And control means for controlling the fuel cut execution means so as to return from the fuel cut under a condition different from the return condition so as not to return from the fuel cut. The control method according to the sixth invention has the same requirements as the control device according to the first invention.

  According to the first or sixth aspect of the invention, the downshift speed change point at the time of deceleration is changed according to the degree of deceleration required at the time of deceleration traveling. The number of cases where the shift shift period overlaps increases probabilistically. In such a case, it does not return from the fuel cut using the normal return condition, but returns from the fuel cut based on another condition (for example, a shift instruction). For this reason, instead of returning from the fuel cut based on the normal return condition, which is a decrease in the rotational speed of the internal combustion engine, the vehicle returns from the fuel cut while avoiding the shift period. And the downshift period can be avoided. For this reason, a shock can be suppressed. As a result, in a vehicle equipped with an automatic transmission that changes the downshift shift point according to the degree of deceleration and an internal combustion engine that executes fuel cut control, the vehicle control device and control that avoid shift shock and fuel cut return shock A method can be provided.

  In the vehicle control device according to the second aspect of the invention, in addition to the configuration of the first aspect, the control means is provided with a condition different from the return condition set based on the number of revolutions of the internal combustion engine. Means for controlling the fuel cut execution means to return. The control method according to the seventh invention has the same requirements as the control device according to the second invention.

  According to the second or seventh aspect of the invention, instead of returning from the fuel cut based on the normal return condition, ie, the state of decrease in the rotational speed of the internal combustion engine, the vehicle returns from the fuel cut while avoiding the shift period. Therefore, it is possible to avoid overlap between the return from the fuel cut and the downshift speed period.

  In the vehicle control apparatus according to the third invention, in addition to the configuration of the first or second invention, the control means returns from the fuel cut under another condition set based on the downshift instruction. Means for controlling the fuel cut execution means. The control method according to the eighth invention has the same requirements as the control device according to the third invention.

  According to the third or eighth invention, the shift period is avoided based on the shift instruction, instead of returning from the fuel cut based on the normal reduction condition, that is, the reduction state of the rotational speed of the internal combustion engine. Since returning from the fuel cut, it is possible to avoid overlap between the return from the fuel cut and the downshift period.

  In the vehicle control apparatus according to the fourth aspect of the invention, in addition to the configuration of any one of the first to third aspects, the changing means includes means for changing the downshift point according to the degree of deceleration. Including. The control method according to the ninth aspect has the same requirements as the control device according to the fourth aspect.

  According to the fourth or ninth aspect of the invention, it is possible to change the downshift shift point to the high vehicle speed side according to the degree of request for deceleration, and output the downshift command at an early stage to achieve the desired deceleration.

  According to a fifth aspect of the present invention, there is provided a control apparatus for a vehicle, wherein, in addition to the configuration of any of the first to fourth aspects, when a fuel cut is being performed, the lockup clutch is engaged or slipped. Means for controlling the lock-up clutch is further included so that the lock-up clutch is released after a predetermined time has elapsed since returning from the fuel cut. The control method according to the tenth invention has the same requirements as the control device according to the fifth invention.

  According to the fifth or tenth invention, the lockup clutch is not released immediately after the return from the fuel cut, but is released after a predetermined time has elapsed since the return from the fuel cut. For this reason, the timing at which the fuel supply is actually restored and the timing at which the lockup clutch is released can be matched or brought close to each other, and an excessive increase in the rotational speed of the internal combustion engine can be suppressed.

  A program according to an eleventh invention is a program for realizing a control method according to any of the sixth to tenth inventions by a computer, and the recording medium according to the twelfth invention is any of the sixth to tenth inventions. This is a medium recording a program for realizing the control method according to the invention by a computer.

  According to the eleventh or twelfth invention, the control method according to any of the sixth to tenth inventions can be realized using a computer (which may be general purpose or dedicated).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, a vehicle equipped with a control device according to the present embodiment includes an engine 150, an intake system 152, an exhaust system 154, an engine ECU (Electronic Control Unit) 100, and an ECT (Electronically Controlled Automatic). Transmission) -ECU 200. The engine 150 transmits power to the drive theory through a stepped 7-speed automatic transmission equipped with a torque converter with a lock-up clutch. Note that the present invention is not limited to a seven-speed automatic transmission. For example, if it is a stepped transmission, it may be 6th speed or 8th speed or more.

  Intake system 152 includes an intake passage 110, an air cleaner 118, an air flow meter 104, a throttle motor 114, a throttle valve 112, and a throttle position sensor 116.

  The air taken in from the air cleaner 118 passes through the intake passage 110 and flows to the engine 150. A throttle valve 112 is provided in the middle of the intake passage 110. The throttle valve 112 is opened and closed when the throttle motor 114 is operated. At this time, the opening degree of the throttle valve 112 can be detected by the throttle position sensor 116. An air flow meter 104 is provided in the intake passage between the air cleaner 118 and the throttle valve 112, and detects the amount of intake air. The air flow meter 104 transmits an intake air amount signal representing the intake air amount Q to the engine ECU 100.

  Engine 150 includes a cooling water passage 122, a cylinder block 124, an injector 126, a piston 128, a crankshaft 130, a water temperature sensor 106, and a crank position sensor 132.

  The cylinder block 124 is provided with a cylinder corresponding to a specific number (the specific number corresponds to the number of cylinders), and each cylinder is provided with a piston 128. An air-fuel mixture of the fuel injected from the injector 126 and the sucked air is introduced into the combustion chamber above the piston 128 through the intake passage 110 and burned by ignition of a spark plug (not shown). When combustion occurs, the piston 128 is pushed down. At this time, the vertical motion of the piston 128 is converted into a rotational motion of the crankshaft 130 via the crank mechanism. The engine ECU 100 detects the engine speed (engine speed ne) based on the signal detected by the crank position sensor 132.

  A cooling water passage 122 is provided in the cylinder block 124, and the cooling water circulates by the operation of a water pump (not shown). The cooling water in the cooling water passage 122 flows to a radiator (not shown) connected to the cooling water passage 122 and is radiated by a cooling fan (not shown). A water temperature sensor 106 is provided on the cooling water passage 122 and detects the temperature (engine cooling water temperature) THW of the cooling water in the cooling water passage 122. Water temperature sensor 106 transmits a signal indicating detected engine cooling water temperature THW to engine ECU 100.

  Exhaust system 154 includes an exhaust passage 108, a first air-fuel ratio sensor 102A, a second air-fuel ratio sensor 102B, a first three-way catalytic converter 120A, and a second three-way catalytic converter 120B. A first air-fuel ratio sensor 102A is provided on the upstream side of the first three-way catalytic converter 120A, and the second is provided on the downstream side of the first three-way catalytic converter 120A (upstream side of the second three-way catalytic converter 120B). The air-fuel ratio sensor 102B is provided. One three-way catalytic converter may be used.

  The exhaust passage 108 connected to the exhaust side of the engine 150 is connected to the first three-way catalytic converter 120A and the second three-way catalytic converter 120B. That is, the exhaust gas generated by the combustion of the air-fuel mixture in the combustion chamber in the engine 150 first flows into the first three-way catalytic converter 120A. HC and CO contained in the exhaust gas flowing into the first three-way catalytic converter 120A are oxidized in the first three-way catalytic converter 120A. Further, NOx contained in the exhaust gas flowing into the first three-way catalytic converter 120A is reduced in the first three-way catalytic converter 120A. The first three-way catalytic converter 120A is installed in the vicinity of the engine 150, and even when the engine 150 is cold-started, the temperature is quickly raised to exhibit a catalytic function.

  Further, the exhaust gas is sent from the first three-way catalytic converter 120A to the second three-way catalytic converter 120B for the purpose of purifying NOx. The first three-way catalytic converter 120A and the second three-way catalytic converter 120B basically have the same structure and function.

  First air-fuel ratio sensor 102A provided upstream of first three-way catalytic converter 120A, provided downstream of first three-way catalytic converter 120A and upstream of second three-way catalytic converter 120B The second air-fuel ratio sensor 102B thus detected detects the concentration of oxygen contained in the exhaust gas that has passed through the first three-way catalytic converter 120A or the second three-way catalytic converter 120B. By detecting the oxygen concentration, it is possible to detect the so-called air-fuel ratio of the fuel and air contained in the exhaust gas.

  The first air-fuel ratio sensor 102A and the second air-fuel ratio sensor 102B generate a current corresponding to the oxygen concentration in the exhaust gas. This current is converted into a voltage, for example, and input to engine ECU 100. Therefore, the air-fuel ratio of the exhaust gas upstream of the first three-way catalytic converter 120A can be detected from the output signal of the first air-fuel ratio sensor 102A, and the second output signal from the second air-fuel ratio sensor 102B can be detected. The air-fuel ratio of the exhaust gas upstream of the three-way catalytic converter 120B can be detected. The first air-fuel ratio sensor 102A and the second air-fuel ratio sensor 102B generate, for example, a voltage of about 0.1 V when the air-fuel ratio is lean, and a voltage of about 0.9 V when the air-fuel ratio is rich. It is what happens. A value converted into an air-fuel ratio based on these values is compared with an air-fuel ratio threshold value, and air-fuel ratio control by engine ECU 100 is performed.

  The first three-way catalytic converter 120A and the second three-way catalytic converter 120B function to reduce NOx while oxidizing HC and CO when the air-fuel ratio is substantially the stoichiometric air-fuel ratio, that is, simultaneously perform HC, CO, and NOx. Has the function of purifying. In these first three-way catalytic converter 120A and second three-way catalytic converter 120B, if the air-fuel ratio is lean and the amount of oxygen in the exhaust gas is large, the oxidizing action becomes active but the reducing action becomes inactive. If the air-fuel ratio is rich and the amount of oxygen in the exhaust gas is small, the reduction action becomes active, but the oxidation action becomes inactive, and all the above three components cannot be purified well.

  The engine ECU 100 is connected to an accelerator pedal opening sensor 160 that detects the opening of the accelerator pedal (accelerator pedal opening ACC) operated by the driver.

  As described above, the output from the engine 150 is transmitted to the drive wheels via the 7-speed automatic transmission provided with a torque converter with a lock-up clutch. Engine ECU 100 is communicably connected to ECT-ECU 200 that controls the automatic transmission. Connected to the ECT-ECU 200 are an AT output shaft rotational speed sensor 210 that detects an output shaft rotational speed (AT output shaft rotational speed no) of the automatic transmission, and a lockup clutch hydraulic circuit 220 that controls the lockup clutch. ing. The ECT-ECU 200 controls a hydraulic circuit that controls the engagement state of friction engagement elements (clutch and brake) of an automatic transmission (not shown), and is based on a map defined by the vehicle speed and the throttle opening. Thus, a desired transmission gear stage is realized. Furthermore, as will be described later, the ECT-ECU 200 changes the downshift point (downshift shift line) according to the degree of deceleration.

  The lock-up clutch hydraulic circuit 220 increases the engagement pressure of the lock-up clutch so that the lock-up clutch is in an engaged state, a released state, or a slip state intermediate between the engaged state and the released state. Control.

  In the following, engine ECU 100 and ECT-ECU 200 will be described as a single ECU.

  The ECU executes fuel cut control when the accelerator pedal is not depressed and the engine speed (engine speed ne) is higher than a predetermined fuel cut permission speed ncut. As a result, fuel injection from the injector 126 is stopped, and fuel consumption and emissions can be improved. Since the fuel supply is stopped, the vehicle speed decreases and the fuel cut control is canceled to prevent engine stall when the engine speed 150 (engine speed ne) is lower than the fuel cut return speed nrt. Thus, fuel injection by the injector 126 is resumed. Further, when the driver steps on the accelerator pedal, there is an acceleration request, so the fuel cut control is stopped and fuel injection by the injector 126 is resumed. At this time, the throttle valve 112 is opened according to the opening of the accelerator pedal, and the intake air amount Q increases.

  As described above, the ECT-ECU 200 changes the downshift shift line (in the case of coast down, the accelerator opening is 0, so the shift line itself is not changed, but the vehicle speed or the automatic transmission output shaft rotation is changed. Of a shift line in a shift map defined by a number no (hereinafter referred to as AT output shaft speed no) (note that these are horizontal axes) and accelerator opening or throttle opening (these are vertical axes). Only the downshift speed change point that is the horizontal axis intercept may be changed). If the vehicle speed (proportional to the AT output shaft rotation speed no) decreases during the fuel cut during the coast down and crosses the downshift line (below the downshift point), the ECU (ECT-ECU200) A downshift command is output to the hydraulic control circuit.

  In such a case, the ECU according to the present embodiment executes the fuel cut control so as to avoid returning from the fuel cut between the downshift command output timing and the timing at which the actual shift is finished. To do. Further, the ECU controls the operation of the lockup clutch after returning from the fuel cut. That is, the deceleration slip control is performed in order to further execute fuel cut during coast down (in order to make it difficult to reduce the engine speed ne), and the lockup clutch is controlled to be in an engaged state or a slip state. (Hereinafter, the fact that the lock-up clutch is controlled to the engaged state or the slip state is described as the lock-up clutch being controlled to the operating state, and the lock-up clutch is controlled to the released state. May be described as the lock-up clutch being controlled to be inactive). This is mainly to avoid a sudden drop in engine speed due to fuel cut, and in case of sudden deceleration (rapid braking), immediately release the lockup clutch and stall the engine. This is to avoid the problem. The ECU controls the timing at which the lockup clutch is changed from the operating state to the non-operating state.

  With reference to FIG. 2, a functional block diagram of the control device according to the present embodiment will be described. As shown in FIG. 2, the control device determines a return from a fuel cut when a downshift point ascending change unit 10000 for early downshifting when the degree of deceleration request is large and a shift command is output. Fuel cut return determination unit 20000, fuel cut return determination unit 30000 for determining a return from the fuel cut when the engine speed ne falls below the fuel cut return rotation number nrt, and a fuel-slip control for deceleration slip control of the lockup clutch LC slip control delay end determination unit 40000 for ending after a predetermined time delay from the return of the vehicle, fuel cut control unit 50000 for executing fuel cut, lockup clutch state (engaged state and slip state operating state, released state) Non And a lock-up clutch control unit 60000 which controls a dynamic state).

  Downshift point increase changing section 10000 is connected to a downshift base rotation speed calculation section 10100 that calculates a downshift base rotation speed that is a normal downshift rotation speed, and a deceleration request degree Δno calculation section 10200. The downshift point increase changing unit 10000 adds the downshift point increase amount shno to the set deceleration request degree Δno (for example, for each current shift gear) to the downshift base rotation speed, and determines the shift command. The downshift shift line (downshift shift point) in the shift map of unit 10300 is changed to the high vehicle speed side. In this way, at the time of deceleration, the timing at which a downshift command is output is changed according to the degree of deceleration request, and when the degree of deceleration request is large, downshifting can be performed earlier and a large deceleration can be realized.

  When the AT output shaft rotational speed no (proportional to the vehicle speed) detected by the AT output shaft rotational speed no detector 10400 crosses the changed downshift line from the high vehicle speed side to the low vehicle speed side (for coasting) Since the throttle opening or the accelerator opening is 0, when the AT output shaft rotational speed no falls below the changed downshift speed change point), a downshift command is output.

  In order to return from the fuel cut, as usual, when the engine speed ne falls below the fuel cut return speed, in addition to the fuel cut return determination unit 30000 that determines to return from the fuel cut, the fuel cut return determination unit 20000 Is provided. The fuel cut return determination unit 20000 returns from the fuel cut when the shift command is output so that the return timing from the fuel cut is not sandwiched between the timing of the downshift command and the actual downshift timing. Judge to do. The fuel cut return determination unit 20000 and the fuel cut return determination unit 30000 are both connected to the fuel cut control unit 50000 and the LC slip control delay end determination unit 40000.

  The fuel cut control unit 50000 is connected to the fuel injection mechanism 50100 (control unit of the injector 126), and performs fuel cut so as not to inject fuel from the injector 126. The lock-up clutch control unit 60000 controls the lock-up clutch hydraulic circuit 60100 so that the lock-up clutch is in one of an operating state (engaged state, slip state) and a non-operating state (released state). To do.

  In the LC slip control delay end determination unit 40000, after a predetermined time has elapsed after returning from the fuel cut, the lock-up clutch in the operating state (engaged state, slip state) is inactivated (released state). Thus, a control signal is output to the lockup clutch hydraulic circuit 60100. This is because the time required for the lock-up clutch hydraulic circuit to actually release the lock-up clutch after the control signal for deactivating the lock-up clutch (released state) is output. Specifically, the fuel supply to the engine 150 is actually restored after the control signal of the return command from the fuel cut is output after the lock-up clutch starts to shift from the operating state to the non-operating state. When compared with the time required to complete the operation (more specifically, the time required for the increase in engine speed and engine torque accompanying the return of fuel supply to reach the input side of the lockup clutch), the former is generally shorter than the latter. (That is, when both control signals are output at the same time, the timing at which the lock-up clutch is inactivated is almost But faster than the timing of the fuel supply is restored, as a result, excessive increase in the engine speed occurs). This is because during a fuel cut, the lock-up clutch tends to be in a slipped state rather than a fully engaged state so that it can be immediately disengaged even in an operating state in preparation for sudden deceleration or the like. This is due to the fact that it takes a relatively long time for the increase in engine rotation and the increase in engine torque to reach the input side of the lockup clutch after the fuel supply is restored. For this reason, at the time of returning from the fuel cut, after a predetermined time has elapsed after outputting the control signal for the return command from the fuel cut, the control signal for the non-operation command for the lockup clutch is output. Thereby, the timing at which the fuel supply is actually returned and the timing at which the lockup clutch is inactivated can be matched or brought close to each other, and an excessive increase in the engine speed ne can be suppressed.

  The control device according to the present embodiment having such a functional block is read from a CPU (Central Processing Unit) and a memory and a memory included in the ECU even in hardware mainly composed of a digital circuit or an analog circuit. It can also be realized by software mainly composed of programs executed by the CPU. In general, it is said that it is advantageous in terms of operation speed when realized by hardware, and advantageous in terms of design change when realized by software. Below, the case where a control apparatus is implement | achieved as software is demonstrated. Note that a recording medium on which such a program is recorded is also an embodiment of the present invention.

  With reference to FIG. 3, the control structure of the program of the downshift point ascending change process executed by the ECU (engine ECU 100 or ECT-ECU 200) will be described. Note that this program is repeatedly executed at a predetermined cycle time. Thereafter, the programs shown in the other flowcharts are similarly repeatedly executed at a predetermined cycle time, and the respective programs converted into subroutines shown in the plurality of flowcharts are executed in parallel. Furthermore, in the following description, turning on an on-state flag indicates that the on-state is maintained, and turning off an off-state flag indicates that the off-state is maintained.

  In step (hereinafter, step is referred to as S) 1000, the ECU substitutes the rotation speed dwn_tbl indicating the downshift point before the change set in the shift map into the base downshift base rotation speed dwno. In the following description, a downshift from 6th speed to 5th speed will be described.

  In S1100, the ECU calculates a deceleration degree Δno. The present invention is not limited to the calculation of the deceleration degree Δno. For example, the deceleration degree Δno is appropriately calculated based on the state of the vehicle, the driver's operation, and the like.

  In S1200, the ECU calculates a shift point increase amount shtno based on a map (shtno_map) set for each transmission gear stage. At this time, for example, as shown by the solid line in FIG. 4, the map (shtno_map) is set so that the shift point increase shno increases as the deceleration degree Δno increases. That is, as the degree of deceleration is larger, the amount of raising is increased in order to downshift at higher vehicle speeds. Note that the map (shtno_map) may be set so that the shift point increase shtno decreases as the deceleration degree Δno increases, as indicated by the one-dot chain line in FIG. 4.

  In S1300, the ECU substitutes (dwno + shtno) for the downshift speed dwno. As a result, the downshift rotational speed (which may be represented by a shift line) indicating the downshift point from the sixth speed to the fifth speed is changed by the shift point increase amount shtno. This state is shown in FIG. Since the throttle opening or the accelerator opening is 0 in this embodiment because the vehicle is decelerating, the downshift speed (downshift point) is reduced by the shift point increase amount shtno described along the horizontal axis of FIG. Rises. As a result, as shown in FIG. 6, the downshift is executed at an early stage according to the deceleration degree Δno.

  In S1400, the ECU detects the AT output shaft rotational speed no. The vehicle speed can be calculated by multiplying the AT output shaft speed no by the gear ratio (final gear ratio) of the differential gear. That is, a proportional relationship is established between the AT output shaft speed no and the vehicle speed.

  In S1500, ECU determines whether or not AT output shaft rotational speed no falls below changed downshift rotational speed dwno. If the AT output shaft speed no falls below the changed downshift speed dwno (YES in S1500), the process proceeds to S1600. If not (NO in S1500), this process ends and the downshift gear shift instruction shtjdg is not changed.

  In S1600, the ECU substitutes (shtjdg-1) for the shift instruction shtjdg. As a result, a downshift instruction from the sixth speed to the fifth speed is generated.

  With reference to FIG. 7, the control structure of the program of the fuel cut return determination process executed by the ECU will be described.

  In S2000, the ECU detects the engine speed ne. At this time, the ECU detects the engine speed ne based on the signal input by the crank position sensor 132.

  In S2100, the ECU detects a fuel cut return rotational speed nrt. The fuel cut return rotation speed nrt is set to a different value depending on the operating state of the lockup clutch (described in detail later), the temperature of the engine 150 (engine cooling water temperature THW), and the like.

  In S2200, the ECU determines whether a condition for determining a natural return from the fuel cut is satisfied. At this time, if the engine rotational speed ne falls below the fuel cut return rotational speed nrt, it is determined that the condition for determining the natural return from the fuel cut is satisfied. If engine speed ne falls below fuel cut return speed nrt and the natural return determination condition from fuel cut is satisfied (YES in S2200), the process proceeds to S2900. If not (NO in S2200), the process proceeds to S2300.

  In S2300, the ECU detects a shift instruction shtjdg. In S2400, ECU determines whether it is a downshift instruction or not. More specifically, it is determined whether or not it is a downshift instruction from 6th gear to 5th gear. If it is determined that it is a downshift instruction (YES in S2400), the process proceeds to S2800. If not (NO in S2400), the process proceeds to S2900.

  In S2800, the ECU turns on (sets) a fuel cut execution premise flag xprfclu in which the lockup clutch is slipped (operated) during deceleration. Thereafter, this process ends.

  In S2900, the ECU turns off (resets) a fuel cut execution premise flag xprfclu that causes the lockup clutch to be in the slip state (actuated state) during deceleration.

  With reference to FIG. 8, the control structure of the program of the fuel cut return rotational speed setting process executed by the ECU will be described.

  In S3000, the ECU calculates a base rotation speed nrtb that returns from the fuel cut. The base rotation speed nrtb is a return rotation speed from the fuel cut that is determined in consideration of factors other than the operation state of the lockup clutch.

  In S3100, the ECU calculates a rotation speed nrtlu that returns from the fuel cut when the lockup clutch is in the slip state (operated state) during deceleration. An example of the return speed from these fuel cuts set for the engine speed ne is that the base speed nrtb is 1200 rpm, the speed nrtlu is 700 rpm, and the like.

  In S3100, the ECU determines whether or not a fuel cut execution premise flag xprfclu that puts the lockup clutch in the slip state (actuated state) at the time of deceleration is on. If flag xprfclu is on (YES in S3200), the process proceeds to S3300. If not (NO in S3200), the process proceeds to S3400.

  In S3300, the ECU calculates the fuel cut return rotational speed by substituting the rotational speed nrtlu for the return rotational speed nrt from the fuel cut. Thereafter, this process ends.

  In S3400, the ECU calculates the fuel cut return rotation speed by substituting base rotation speed nrtb for the return rotation speed nrt from the fuel cut.

  With reference to FIG. 9, a control structure of a program for a determination process for ending the slip control of the lockup clutch executed by the ECU with a delay from the fuel cut return will be described. In the flowchart shown in FIG. 9, the same steps as those shown in other flowcharts are denoted by the same step numbers. The contents of those processes are the same. Therefore, detailed description thereof will not be repeated here. It should be noted that the description is not repeated in this way for the flowcharts described below.

  In S4000, the ECU determines whether a condition for determining a natural return from the fuel cut is satisfied. At this time, if the engine rotational speed ne falls below the fuel cut return rotational speed nrt, it is determined that the condition for determining the natural return from the fuel cut is satisfied. If engine speed ne falls below fuel cut return speed nrt and the natural return determination condition from fuel cut is satisfied (YES in S4000), the process proceeds to S4400. If not (NO in S4000), the process proceeds to S4100.

  In S4100, the ECU sets 0 to a counter cacr that is used to end the slip state (actuated state) of the lockup clutch during deceleration. Note that this counter cacr is an addition counter, and the ECU can determine whether or not the addition value (count value) has reached a preset counter threshold value (threshold value B described later).

  In S4200, the ECU detects a fuel cut permission rotational speed ncut. If the engine speed ne is equal to or greater than the permitted engine speed ncut, the fuel cut is permitted and the fuel cut is executed.

  In S4300, the ECU determines whether or not the engine speed ne is less than the permitted engine speed ncut. If engine speed ne falls below allowable speed ncut (YES in S4300), the process proceeds to S4400. If not (NO in S4300), the process proceeds to S4500.

  In S4400, the ECU turns off (resets) fuel cut execution flag xfcidl. Thereafter, the process proceeds to S4600.

  In S4500, the ECU sets (sets) a fuel cut execution flag xfcidl.

  In S4600, the ECU determines whether or not the addition value (count value) of counter cacrc that has started counting after fuel cut execution flag xfcidl is turned off has reached preset counter threshold value B. To do. If the addition value (count value) of counter cfcr reaches counter threshold value B (YES in S4600), the process proceeds to S4700. If not (NO in S4600), the process proceeds to S4800. The counter threshold value B can match or approach the timing at which the fuel supply is actually restored and the timing at which the lockup clutch is deactivated, thereby suppressing an excessive increase in the engine speed ne. Is set to be able to.

  In S4700, the ECU turns on (sets) a slip control end instruction flag xslucn for making the lock-up clutch in the slip state (actuated state) in the non-actuated state (release state) at the time of the deceleration fuel cut. For this reason, the lock-up clutch is changed from the operating state to the released state, which is delayed by the time until the counter cafcr after returning from the fuel cut reaches the set threshold value B. Thereafter, this process ends.

  In S4800, the ECU turns off (resets) slip control end instruction flag xslucn for disabling (releasing) the lock-up clutch that has been slipping (operating) at the time of deceleration fuel cut.

  The operation of the vehicle controlled by the control device according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG.

  At time t (1) in FIG. 10, a downshift instruction from 6th gear to 5th gear is output during coasting (YES in S1500 and YES in S1600 and YES in S2300 and S2400). At this time, the downshift line (downshift point) from the sixth speed to the fifth speed is changed to the higher vehicle speed side according to the degree of deceleration as shown in FIGS. 4 to 6 (S1000 to S1000). S1300).

  When fuel cut is executed with the lock-up clutch in the slip state (actuated state) during deceleration, that is, when the engine speed ne in the fuel cut natural return state is equal to or higher than the fuel cut return speed nrt. (NO in S2200) When this downshift instruction is detected (YES in S2400), the fuel cut execution premise flag xprfclu in which the lockup clutch is slipped (operated) at the time of deceleration is turned on. Is maintained (S2900). That is, when the shift instruction is detected, the execution premise flag xprfclu is kept on, so that it is possible to avoid returning from the fuel cut during the shift period. For this reason, the shift period and the return timing from the fuel cut do not overlap.

  When the engine speed ne in the fuel cut natural return state becomes lower than the fuel cut return speed nrt (YES in S2200), the fuel cut execution precondition flag that sets the lockup clutch to the slip state (operating state) during deceleration xprfclu is turned off (S2900). Specifically, if a fuel cut natural return condition is satisfied when no shift instruction is detected (YES in S2200, NO in S2400), the precondition for executing fuel cut with the lockup clutch in the slip state (operating state) during deceleration The flag xprfclu is turned off (S2900), and the process returns from the fuel cut. For this reason, the shift period and the return timing from the fuel cut do not overlap.

  Thus, it is avoided that the return from the fuel cut overlaps during the speed change operation. For this reason, it can avoid that a shock becomes large.

  Furthermore, when the return from the fuel cut is executed at a timing that does not overlap with the speed change operation in this way (more specifically, when the fuel cut execution flag xfcidl is turned off), the fuel cut execution flag xfcidl It is determined whether or not the added value (count value) of the counter cacrc that has started counting since the signal is turned off has reached a preset counter threshold value B (S4600). If a predetermined time elapses from the return of the fuel cut until the addition value (count value) of the counter cacr reaches the preset counter threshold value B (YES in S4600), the slip state (actuation is activated during the deceleration fuel cut) The slip control end instruction flag xslucn for setting the lock-up clutch that has been set to the non-actuated state (released state) is turned on (S4700). This is the timing indicated by time t (2) in FIG.

  At this time t (2), the lock-up clutch is brought into a disengaged state, which is an inoperative state, with a delay after the time when the counter cafécr after returning from the fuel cut reaches the set value B. By doing in this way, at the time of fuel cut return, after outputting the control signal of the return command from the fuel cut, the control signal of the lock-up clutch non-operation command is output after a predetermined time has elapsed. The timing at which the fuel supply is restored and the timing at which the lockup clutch is deactivated can be matched or brought close to each other, and an excessive increase in the engine speed ne can be suppressed.

As described above, in a vehicle equipped with an engine that performs fuel cut control and an automatic transmission that includes a torque converter with a lock-up clutch,
(1) Change the downshift point to a higher vehicle speed according to the degree of deceleration request, and output a downshift command at an early stage to achieve a desired deceleration.
(2) When the fuel cut is executed by operating the lock-up clutch (deceleration slip control), a return from the fuel cut, and a downshift operation based on the downshift point changed in (1) above To avoid the overlapping of the shock and suppress the shock,
(3) Immediately after returning from the fuel cut, the lockup clutch is not deactivated (released), but after a predetermined time has elapsed from the return from the fuel cut, the lockup clutch is deactivated (released). Thus, the timing at which the fuel supply is actually restored and the timing at which the lock-up clutch is inactivated can be matched or brought close to each other, and an excessive increase in the engine speed ne can be suppressed.

<Modification>
Hereinafter, modifications of the embodiment of the present invention will be described. In this modification, a program represented by a flowchart different from the program represented by the flowchart shown in FIG. 7 is executed. Other structures are the same as those of the above-described embodiment. Therefore, description thereof will not be repeated here.

  With reference to FIG. 11, the control structure of the program for the fuel cut return determination process executed by the ECU will be described. In the flowchart shown in FIG. 11, the same processes as those in FIG. 7 are given the same step numbers. The contents of those processes are the same. Therefore, description thereof will not be repeated here.

  In S5000, the ECU determines whether or not the shift instruction shtjdg is 5th speed or less. If shift instruction shtjdg is 5th or less (YES in S5000), the process proceeds to S2900. If not (NO in S5000), the process proceeds to S2800.

  That is, when the timing A (time t (3)) in FIG. 10 is earlier than the timing (time t (1)) at which the shift instruction is output (the timing at which the shift instruction is output on the left side of FIG. If there is, a return from the fuel cut is executed at the timing (time t (1)) when the shift instruction is output.

  Even in this case, when the fuel cut is executed by operating the lockup clutch (deceleration slip control), it is possible to avoid the overlap between the return from the fuel cut and the downshift operation, so that the shock can be avoided. Can be suppressed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a control block diagram of a vehicle on which a control device according to an embodiment of the present invention is mounted. It is a functional block diagram of a control device concerning an embodiment of the invention. It is a flowchart (the 1) which shows the control structure of the program performed by ECU which is a control apparatus which concerns on embodiment of this invention. It is a figure which shows the map showing the relationship between the deceleration degree and a shift point rise. It is a figure which shows the change state of a downshift transmission line. It is a figure which shows the change state of the shift timing accompanying the change of a downshift shift line. It is a flowchart (the 2) which shows the control structure of the program performed by ECU which is a control apparatus which concerns on embodiment of this invention. It is a flowchart (the 3) which shows the control structure of the program performed with ECU which is a control apparatus which concerns on embodiment of this invention. It is a flowchart (the 4) which shows the control structure of the program performed by ECU which is a control apparatus which concerns on embodiment of this invention. It is a timing chart which shows operation | movement of the vehicle performed by ECU which is a control apparatus which concerns on embodiment of this invention. It is a flowchart which shows the control structure of the program performed by ECU which is a control apparatus which concerns on the modification of embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Engine ECU, 102A 1st air fuel ratio sensor, 102B 2nd air fuel ratio sensor, 104 Air flow meter, 106 Water temperature sensor, 108 Exhaust passage, 110 Intake passage, 112 Throttle valve, 114 Throttle motor, 116 Throttle position sensor, 118 air cleaner, 120A first three-way catalytic converter, 120B second three-way catalytic converter, 122 cooling water passage, 124 cylinder block, 126 injector, 128 piston, 130 crankshaft, 150 engine, 152 intake system, 154 exhaust system 160 Accelerator pedal opening sensor, 200 ECT-ECU, 210 AT output shaft rotational speed sensor, 220 Lock-up clutch hydraulic circuit.

Claims (12)

A vehicle control device equipped with an internal combustion engine that executes fuel cut control and a stepped automatic transmission,
Changing means for changing the downshift point during deceleration;
When the vehicle state satisfies a predetermined execution condition, a fuel cut is performed to stop fuel supply to the internal combustion engine, and when the vehicle state satisfies a predetermined return condition, the vehicle returns from the fuel cut. A fuel cut execution means for controlling the internal combustion engine,
The fuel cut execution means is configured to return from the fuel cut under a condition different from the return condition so as not to return from the fuel cut during a downshift speed change period executed based on the downshift speed change point. And a control means for controlling the vehicle.   The control means includes means for controlling the fuel cut execution means to return from the fuel cut under a condition different from a return condition set based on the rotational speed of the internal combustion engine. The vehicle control device according to claim 1.   The said control means is a means for controlling the said fuel cut execution means to make it return from the said fuel cut on another condition set based on the said downshift instruction | indication, The claim 1 or 2 Vehicle control device.   The vehicle control device according to claim 1, wherein the changing unit includes a unit for changing the downshift point according to a degree of deceleration. The vehicle includes a fluid coupling with a lock-up clutch,
The control device of the vehicle is predetermined so that the lock-up clutch is engaged or slipped when the fuel cut is being performed, and after returning from the fuel cut. The vehicle control device according to claim 1, further comprising means for controlling the lockup clutch such that the lockup clutch is released after a lapse of a predetermined time. A control method for a vehicle equipped with an internal combustion engine that executes fuel cut control and a stepped automatic transmission,
A change step for changing the downshift point during deceleration;
When the vehicle state satisfies a predetermined execution condition, a fuel cut is performed to stop fuel supply to the internal combustion engine, and when the vehicle state satisfies a predetermined return condition, the vehicle returns from the fuel cut. A fuel cut execution step for controlling the internal combustion engine,
The fuel cut execution step so as to return from the fuel cut under a condition different from the return condition so as not to return from the fuel cut during a down shift speed change period executed based on the down shift speed change point. And a control step for controlling the vehicle.   The control step includes a step of controlling the fuel cut execution step so as to return from the fuel cut under a condition different from a return condition set based on the rotational speed of the internal combustion engine. The vehicle control method described.   The vehicle according to claim 6 or 7, wherein the control step includes a step of controlling the fuel cut execution step so as to return from the fuel cut under another condition set based on the downshift instruction. Control method.   The vehicle control method according to any one of claims 6 to 8, wherein the changing step includes a step of changing the downshift point according to a degree of deceleration. The vehicle includes a fluid coupling with a lock-up clutch,
The vehicle control method is determined in advance so that the lock-up clutch is engaged or slipped when the fuel cut is being performed, and after returning from the fuel cut. The vehicle control method according to claim 6, further comprising a step of controlling the lockup clutch such that the lockup clutch is released after a lapse of a predetermined time.   The program which makes a computer implement | achieve the control method in any one of Claims 6-10.   A recording medium on which a program for causing a computer to implement the control method according to claim 6 is recorded.

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