Negative pressure control method and device for vehicle internal combustion engine

Abstract

To efficiently secure negative pressure for a negative pressure type brake booster without stopping operation of an alternator.SOLUTION: When braking a vehicle with an acceleration opening in a state equivalent to fully closed, lock-up operation of a lock-up clutch is executed in addition to fuel cut operation so as to enable a vehicle to perform coasting operation in a lock-up state (time t1 to t2). An alternator is driven through the coasting operation. The lock-up operation and the fuel cut operation are released at time t2 before the vehicle is stopped. While the vehicle is in normal travel or in a non-lock-up state, a normal correction air amount according to alternator drive torque is proved as an air amount to be an electric power generation load of the alternator (Qa1 and Qa3). Because the correction air amount is reduced to a predetermined reduced correction air amount (Qa2) while the vehicle is decelerated in the lock-up state, negative pressure can be developed with an opening of a throttle valve reduced.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a negative pressure control of an internal combustion engine for a vehicle, which serves as a negative pressure source for a vacuum brake booster. [Background technology]

[0002] A vacuum-type brake booster is known as one of the components of a vehicle brake system, and in many cases, the intake vacuum generated in the intake system of an internal combustion engine is used as the vacuum source for the vacuum-type brake booster. In such a configuration, it is necessary to supply a sufficient level of vacuum to the vacuum-type brake booster so that the vacuum in the vacuum-type brake booster does not become insufficient depending on driving conditions, etc.

[0003] Patent Document 1 discloses a technology that stops the operation of so-called accessories, such as an air conditioner compressor and an alternator driven by an internal combustion engine, when the negative pressure in a vacuum-type brake booster falls below a predetermined level. By stopping the operation of these accessories, the opening of the throttle valve of the internal combustion engine becomes relatively small, and intake negative pressure develops downstream of the throttle valve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-208729 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it is not desirable to stop the operation of auxiliary machinery even temporarily as described above. For example, if an air conditioner compressor is stopped, the refrigeration cycle will stop while the compressor is stopped, and if an alternator is stopped, power generation will not be generated while the compressor is stopped. [Means for solving the problem]

[0006] This invention is provided with a vacuum type brake booster that uses the intake vacuum downstream of the throttle valve of the internal combustion engine as a vacuum source, and a torque converter provided between the engine and the transmission that is provided with a lock-up clutch. and a generator as an auxiliary machine driven by the output of the internal combustion engine. Vehicle internal combustion engine By controller A negative pressure control method, comprising: When the vehicle decelerates to a fully closed throttle position, A fuel cut is performed in accordance with a predetermined fuel cut condition, and the lockup clutch is controlled to either a lockup state or a non-lockup state in accordance with a predetermined lockup condition. The command voltage of the generator is controlled to be higher than the command voltage during normal driving when the vehicle is decelerating in a lockup state, a normal correction air amount is calculated in accordance with an accessory drive torque required to drive the generator, and when the vehicle is decelerating during normal running or in a non-lockup state, the normal correction air amount is used as an additional amount for the accessory to control the intake air amount of the internal combustion engine via the throttle valve; During deceleration in a lockup state, the intake air amount of the internal combustion engine is controlled via the throttle valve by using a fixed reduced correction air amount, which is relatively smaller than the normal correction air amount and is unrelated to the accessory drive torque, as an increase amount for the accessory.

[0007] If the vehicle is locked up, even if fuel is cut, the internal combustion engine will continue to rotate as the vehicle coasts, and the auxiliary engine will not A generator that is The drive of continues. As the command voltage increases, power generation is performed by actively utilizing deceleration energy, As the amount of intake air into the internal combustion engine decreases, intake vacuum develops and accumulates in the vacuum-type brake booster. [Effects of the Invention]

[0008] According to this invention, generator The vacuum brake booster can be effectively supplied with vacuum pressure during deceleration without stopping the vehicle. It is possible to achieve both power generation and negative pressure. do. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating the configuration of an internal combustion engine for a vehicle according to an embodiment of the present invention; [Figure 2] 4 is a flowchart of negative pressure control in the first embodiment. [Figure 3] 4 is a time chart illustrating an operation under negative pressure control in the first embodiment. [Figure 4] 10 is a flowchart of a second embodiment for correcting the gear ratio at high altitudes. [Figure 5] 10 is a time chart showing the speed ratio correction at high altitude in the second embodiment; [Figure 6] 10 is a flowchart of a third embodiment for correcting an instruction voltage. [Figure 7]10 is a time chart illustrating an operation under negative pressure control in the third embodiment. [Figure 8] FIG. 2 is a functional block diagram of a negative pressure control including a first embodiment and a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0011] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a vehicle internal combustion engine 1 to which the negative pressure control of the present invention is applied. The internal combustion engine 1 is a spark-ignition internal combustion engine that uses, for example, gasoline as fuel and includes an auxiliary generator, for example, an alternator 2. The alternator 2 is driven by rotation of the crankshaft of the internal combustion engine 1 via a belt transmission mechanism 3. The power generated by the alternator 2 supplies power to the ignition system of the internal combustion engine 1 and to electrical components of the vehicle, and also charges a battery (not shown, for example, a battery rated at 12 V). The internal combustion engine 1 drives drive wheels (not shown) via a transmission 4, for example, a belt-type continuously variable transmission (so-called CVT), and a torque converter 5 is provided between the transmission 4 and the internal combustion engine 1. The torque converter 5 includes a lock-up clutch 6 that directly connects a pump impeller to a turbine runner.

[0012] A throttle valve 8 that controls the amount of intake air is provided in an intake passage 7 of the internal combustion engine 1. This throttle valve 8 has an actuator (not shown), and its opening is controlled based on a control signal from a controller 9. A vacuum-type brake booster 10 in the vehicle's brake device uses the intake negative pressure generated downstream of the throttle valve 8 as a negative pressure source, and the negative pressure is supplied via a vacuum passage 11 from, for example, an appropriate position in the intake passage 7 or a collector section (not shown), etc.

[0013] The controller 9 includes a plurality of control units, such as an engine control unit and a CVT control unit, which are interconnected via an interface such as CAN communication. Signals are input to the controller 9 from numerous sensors (not shown), and various controls of the internal combustion engine 1 and the transmission 4 are performed based on these signals. For example, detection signals from an accelerator position sensor that detects the position of an accelerator pedal operated by the driver, a brake switch that detects a brake operation, a rotational speed sensor that detects the rotational speed of the internal combustion engine 1, an air flow meter that detects the intake air amount of the internal combustion engine 1, a water temperature sensor that detects the coolant temperature of the internal combustion engine 1, a vehicle speed sensor that detects the vehicle speed, an atmospheric pressure sensor that detects the atmospheric pressure, an intake pressure sensor that detects the intake negative pressure in the collector, and the like are input to the controller 9. The amount of fuel injection and ignition timing of the internal combustion engine 1, the opening of the throttle valve 8, the engagement and disengagement of the lock-up clutch 6, the gear ratio of the transmission 4, the operation of the alternator 2, and the like are controlled by the controller 9. The voltage generated by the alternator 2 is controlled to be substantially constant via a voltage regulator, and more specifically, is set variably in accordance with a command voltage issued by the controller 9 .

[0014] Next, a description will be given of vacuum control for supplying sufficient vacuum to the vacuum brake booster 10. The alternator 2, which is an accessory of the internal combustion engine 1, is driven using part of the output of the internal combustion engine 1. Therefore, it is necessary to increase the output torque of the internal combustion engine 1 by the amount of the drive torque of the alternator 2 (alternator drive torque), and it is necessary to increase the intake air amount corresponding to this increase in torque. Meanwhile, the alternator drive torque varies depending on the operating state (power generation amount) of the alternator 2. Therefore, the controller 9 always calculates the increase in the air amount corresponding to this alternator drive torque as the normal correction air amount for the alternator, and basically, the required intake air amount is calculated by adding this normal correction air amount, and the opening of the throttle valve 8 is controlled to obtain this intake air amount.

[0015] In contrast, when the vehicle decelerates and the accelerator pedal position becomes equivalent to a fully closed position, fuel is cut off in accordance with predetermined fuel-cut conditions, and lock-up clutch 6 may be locked up as a so-called coast lock-up in accordance with predetermined lock-up conditions. In such a lock-up state, even if fuel is being cut off, the crankshaft of internal combustion engine 1 rotates as the vehicle coasts, driving alternator 2. Therefore, a fixed correction air amount (hereinafter referred to as a decrease correction air amount) that is reduced by a relatively small amount is applied as an increase in the amount of air for alternator 2, regardless of fluctuations in alternator drive torque. Note that this decrease correction air amount is set to an amount that will prevent internal combustion engine 1 from stalling the instant lock-up is released.

[0016] Therefore, when the vehicle decelerates with the accelerator pedal position equivalent to fully closed, if the lockup clutch 6 is in a locked-up state, the amount of intake air into the internal combustion engine 1 is relatively small compared to when the lockup clutch 6 is not in a locked-up state. As a result, the opening of the throttle valve 8 becomes relatively small during lockup, and a correspondingly strong negative pressure can be generated.

[0017] FIG. 2 shows a flowchart of the negative pressure control of the first embodiment executed by the controller 9. In step 1, it is determined whether three conditions are simultaneously met: lockup is in progress, fuel is being cut, and the accelerator opening is equivalent to fully closed (i.e., idling is being determined). If the answer is YES, the process proceeds to step 2, where the normal correction air amount, which is calculated sequentially in response to the driving torque of the alternator 2, is compared with the relatively small, fixed decrease correction air amount. Normally, the normal correction air amount is larger than the decrease correction air amount. Therefore, the process proceeds from step 2 to step 3, where an opening command is output to the throttle valve 8 (abbreviated as ETC) using the decrease correction air amount.

[0018] If the condition in step 1 is not met, or if the normal correction air amount is smaller than the decrease correction air amount, the process proceeds to step 4, where the normal correction air amount is used to output an opening command to the throttle valve 8. For example, when the engine is not in lockup, the intake air amount is increased by the normal correction air amount.

[0019] FIG. 3 is a time chart illustrating the operation of the negative pressure control of the first embodiment. This chart shows the behavior of the vehicle from a state in which the accelerator pedal is on until the driver releases the accelerator pedal, decelerating, and finally stopping. From top to bottom, the chart shows vehicle speed, lock-up flag, fuel cut flag, power supply current, alternator corrected air flow rate, intake negative pressure, and brake booster negative pressure. As shown in the vehicle speed column, the vehicle is in normal driving mode up to time t1, decelerating from time t1 to t3, and stopped from time t3 onward. During normal driving, in this example, the lock-up flag is ON, and lock-up is performed. Then, during deceleration, the vehicle is controlled to a lock-up state in accordance with a predetermined lock-up condition until it decreases to a predetermined vehicle speed or a predetermined engine speed, that is, from time t1 to time t2. Then, at time t2, the vehicle speed or engine speed falls below the lower limit of the lock-up condition, and lock-up is released. Therefore, the lock-up state is not maintained from time t2 onward. As shown by the fuel cut flag, fuel is cut between times t1 and t2 in accordance with predetermined fuel cut conditions as the vehicle decelerates. Note that fuel injection is resumed almost simultaneously with the release of lockup at time t2 to prevent the engine speed from dropping excessively, making restart difficult.

[0020] The characteristics of the power supply current roughly correspond to the alternator drive torque. In this example, as will be described later, the command voltage of the alternator 2 is set higher than that during normal running during the coasting period from time t1 to time t2, when the vehicle is coasting, in order to efficiently recover energy. Therefore, the power supply current also has a characteristic of increasing during the period from time t1 to time t2.

[0021] The column for alternator correction air volume shows the air increase for alternator 2 described above, but the air volume Qa1 during normal driving up to time t1 is the normal correction air volume described above. Similarly, the air volume Qa3 during the period from time t2 onward, when the lockup state is eliminated, is the normal correction air volume described above. These Qa1 and Qa3 are simplified as constant values ​​in the figure, but in reality, they have characteristics that fluctuate depending on the alternator drive torque. In contrast, the air volume Qa2 during deceleration in the lockup state from time t1 to time t2 is the decreased correction air volume described above. This is a constant value that does not respond to changes in the alternator drive torque. Furthermore, this air volume is smaller than the air volumes Qa1 and Qa3 in the preceding and following periods.

[0022] As a result, as shown in the column for suction negative pressure, the suction negative pressure Pe2 in the section from time t1 to time t2 is lower than the suction negative pressures Pe1 and Pe3 in the sections before and after, and the negative pressure in the vacuum brake booster 10 is also similarly low. In the section from time t1 to time t2, the alternator 2 is driven by the energy generated by the vehicle coasting.

[0023] If deceleration between time t1 and time t2 were performed in a non-lockup state due to reasons such as the lockup condition not being satisfied, the correction air amount for that section would be the normal correction air amount corresponding to the alternator drive torque. In particular, because the command voltage is set higher than during normal driving, as described above, and the alternator drive torque is high, the air amount characteristic would be larger than the front and rear air amounts Qa1 and Qa3, as shown by the dotted line Qa2'. As a result, the generated intake vacuum and the vacuum pressure inside vacuum pressure brake booster 10 would also have the characteristics of a relatively weak vacuum, as shown by the dotted lines.

[0024] In this way, in the above embodiment, negative pressure can be efficiently stored in the vacuum type brake booster 10 by utilizing the time when the vehicle is decelerating and lockup is performed along with fuel cut, and the battery can be efficiently charged by driving the alternator 2. In other words, it is possible to achieve both efficient battery charging and ensuring negative pressure in the vacuum type brake booster 10.

[0025] As shown in the time chart of Fig. 3, when switching between the normal correction air amount and the decrease correction air amount at time t1 or t2, control is performed so that an appropriate change speed is achieved, but this is not the main part of the present invention, so a description thereof will be omitted. The same applies to the time charts of Fig. 5 and Fig. 7 described later.

[0026] Next, a second embodiment will be described, in which a gear ratio is corrected to ensure sufficient vacuum at high altitudes. At high altitudes, where the air density is lower, the throttle valve 8 opening is larger for the same load and rotational speed than at low altitudes, resulting in a tendency for the vacuum in the vacuum brake booster 10 to be insufficient. In the second embodiment, the gear ratio of the CVT transmission 4 is relatively increased (shifted to a low gear), thereby relatively increasing the rotational speed of the internal combustion engine 1 at the same vehicle speed and strengthening the intake vacuum. The basic gear ratio (normal gear ratio) of the CVT transmission 4 is determined based on a predetermined gear ratio map using, for example, vehicle speed and accelerator position as parameters. The gear ratio for strengthening the vacuum (vacuum development gear ratio) is set by shifting the characteristics of this normal gear ratio to a low gear. Alternatively, a separate gear ratio map may be prepared.

[0027] 4 shows a flowchart of the gear ratio correction control of the second embodiment executed by the controller 9. In step 11, it is determined whether three conditions are simultaneously met: that the atmospheric pressure sensor signal indicates high altitude, that the vehicle is in lockup, and that the accelerator opening is equivalent to fully closed (i.e., the vehicle is being determined to be idling). If the answer is YES, the process proceeds to step 12, where it is confirmed that the vacuum development speed ratio is greater than the normal speed ratio, and then the process proceeds to step 13, where the gear ratio of the transmission 4 is controlled at the vacuum development speed ratio. If the condition in step 11 is not met, or if the vacuum development speed ratio is smaller than the normal speed ratio, the process proceeds to step 14, where the gear ratio of the transmission 4 is controlled at the normal speed ratio.

[0028] 5 is a time chart for explaining the operation of the gear ratio correction control of the second embodiment, and shows, from top to bottom, the characteristics of vehicle speed, lock-up flag, idle determination flag, gear ratio, engine speed, intake vacuum, and altitude determination (i.e., high altitude determination flag). As is clear from the vehicle speed, lock-up flag, and idle determination flag, the vehicle is running normally up to vehicle speed time t1, is running at deceleration in a lock-up state from time t1 to t2, is running at deceleration in a non-lock-up state from time t2 to t3, and is stopped from time t3 onwards.

[0029] In the illustrated example, the high altitude is determined as indicated by the high altitude determination flag, and therefore, in the time period from t1 to t2, the gear ratio is corrected from the normal gear ratio (shown by the dashed line) to the negative pressure development gear ratio (shown by the solid line). As a result, the engine speed increases from Ne1 (shown by the dashed line) to Ne2 (shown by the solid line), and the intake negative pressure decreases from Pe11 (shown by the dashed line) to Pe12 (shown by the solid line).

[0030] By combining this high altitude correction of the gear ratio with the negative pressure control of the first embodiment described above, it is possible to ensure the negative pressure of the negative pressure brake booster 10 while efficiently charging the battery even at high altitudes.

[0031] Next, a third embodiment will be described with reference to Figures 6 and 7. In the third embodiment, the command voltage of the alternator 2 is temporarily corrected to more reliably suppress engine stall when deceleration in a lockup state is followed by release of the lockup state in the negative pressure control of the first embodiment described above. The basic control, excluding the control when the lockup state is released, is the same as the negative pressure control of the first embodiment.

[0032] 6 is a flowchart of the negative pressure control of the third embodiment. In step 21, similar to step 1 in FIG. 2 described above, it is determined whether the three conditions of lockup, fuel cut, and the accelerator opening equivalent to fully closed (i.e., idling) are simultaneously met. If the answer is YES, the process proceeds to step 22, where it is confirmed that the decrease correction air amount is smaller than the normal correction air amount, and then the process proceeds to step 23, where an opening command is output to the throttle valve 8 (ETC) using the decrease correction air amount.

[0033] If the condition of step 11 is not satisfied and if the normal correction air amount is smaller than the reduction correction air amount, the process proceeds to step 24, where an opening command is output to the throttle valve 8 using the normal correction air amount. Then, from step 24, the process proceeds to step 25, where it is determined whether or not the alternator power generation limit period is in progress. The alternator power generation limit period is, for example, set to an appropriate time in advance, and a timer starts to measure the time when the process proceeds from step 24 to step 25 for the first time. Until the alternator power generation limit period has elapsed, the process proceeds from step 25 to step 26, where the command voltage of the alternator 2 is limited to a voltage lower than normal. Once the alternator power generation limit period has elapsed, the process proceeds from step 25 to step 27, where normal power generation control is performed without limiting the command voltage. The alternator power generation limit period can be a relatively short period of, for example, less than one second.

[0034] FIG. 7 is a time chart illustrating the operation of the negative pressure control of the third embodiment, and shows the operation during deceleration similar to that of FIG. 2 of the first embodiment. In particular, the command voltage characteristics and the power supply voltage characteristics based thereon are added. As described in the first embodiment, during the lockup state and the fuel cut-off period from time t1 to time t2, the aforementioned relatively small, constant, decreased corrected air amount Qa2 is applied as the air amount for the power generation load. Then, at time t2, the fuel cut-off ends and the lockup is released. From time t2 until the alternator power generation limit period has elapsed, the command voltage is limited to a low value (V4 in the figure).

[0035] For example, assuming a battery rated at 12 V, the command voltage can be variably set within a range of approximately 11.5 V to 14.3 V, but command voltages V1 and V3 during normal driving or when the vehicle is stopped are controlled to an intermediate range of approximately 12 to 13 V, and command voltage V2 during deceleration in a lockup state is controlled to a relatively high level of approximately 14 V to actively utilize deceleration energy for power generation.In contrast, immediately after lockup is released (i.e., during the period when alternator power generation is limited), the command voltage is limited to approximately 11.5 V, which is close to the lower limit of the controllable range, as shown by V4.

[0036] By lowering the command voltage in this way, the alternator driving torque is temporarily reduced, and stalling of the internal combustion engine 1 due to a delayed response to a change in the intake air amount or the like is reliably prevented.

[0037] FIG. 8 is a functional block diagram showing the control of the first and third embodiments described above. Each block is configured as software or hardware within the controller 9. As shown in the figure, one of the control functions of the internal combustion engine 1 is a lock-up / coast alternator air amount subtraction unit 51, which includes an alternator air amount reduction permission determination unit 52, an alternator air amount reduction value calculation unit 53, an alternator air amount calculation unit 54, an auxiliary load air amount command unit 55, an alternator air amount reduction value calculation unit (normal / reduction switching) 56, and an ETC opening command unit 57. The normal correction air amount described above is calculated by the alternator air amount calculation unit 54 and the auxiliary load air amount command unit 55. The alternator air amount reduction permission determination unit 52 performs a determination similar to that of step 1 described above. The alternator air amount reduction value calculation unit 53 calculates the aforementioned reduction correction air amount and its change rate (decrease rate and increase rate). An alternator air reduction value calculation unit (normal / reduction switching) 56 switches between the normal correction air amount and the reduction correction air amount in accordance with the determination by the alternator air reduction permission determination unit 52. Then, the opening of the throttle valve 8 is controlled by an ETC opening command unit 57 in accordance with this.

[0038] The alternator cut unit 61, which corresponds to the third embodiment, calculates the target command voltage when limiting the command voltage, and also calculates the cut hold time, i.e., the alternator power generation limit period, described above. Based on these, the command voltage of the alternator 2 immediately after the lockup is released is limited.

[0039] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment and various modifications are possible. .B The above-described decrease correction air amount that is set when the vehicle decelerates in the backup state may be a constant value that is not linked to the accessory drive torque, and the value of the decrease correction air amount may be variably set based on other conditions or parameters, such as the temperature condition of the internal combustion engine 1. Similarly, the limit value of the command voltage in the third embodiment may be variably set in accordance with some parameter.

[0040] Furthermore, the transmission 4 may be a stepped transmission instead of a CVT. Furthermore, the amount of air for the accessories can be adjusted by adjusting the flow rate in a bypass passage that bypasses the throttle valve, rather than by controlling the opening of the throttle valve 8. The high altitude can also be determined by using a car navigation system that uses GPS. [Explanation of symbols]

[0041] 1...Internal combustion engine 2...Alternator 4...Gearbox 5...Torque converter 6...Lock-up clutch 8...Throttle valve 9...Controller 10...Vacuum brake booster

Claims

1. A method for controlling negative pressure by a controller of a vehicle internal combustion engine, the vehicle internal combustion engine having a vacuum type brake booster that uses the intake negative pressure downstream of a throttle valve of the internal combustion engine as a negative pressure source, a torque converter provided between the internal combustion engine and a transmission that has a lock-up clutch, and a generator as an auxiliary machine driven by the output of the internal combustion engine, comprising: When the vehicle is decelerating and the accelerator opening is equivalent to a fully closed position, fuel is cut off in accordance with predetermined fuel cut conditions, and the lock-up clutch is controlled to either a lock-up state or a non-lock-up state in accordance with predetermined lock-up conditions, The command voltage of the generator is controlled to be higher than the command voltage during normal driving when the vehicle is decelerating in a lockup state, a normal correction air amount is calculated in accordance with an accessory drive torque required to drive the generator, and when the vehicle is decelerating during normal running or in a non-lockup state, the normal correction air amount is used as an additional amount for the accessory to control the intake air amount of the internal combustion engine via the throttle valve; During deceleration in a lockup state, a constant decrease correction air amount, which is relatively smaller than the normal correction air amount and is unrelated to the accessory drive torque, is used as an increase air amount for the accessory, and the intake air amount of the internal combustion engine is controlled via the throttle valve. A method for controlling negative pressure in an internal combustion engine for a vehicle.

2. 2. The method for controlling negative pressure in a vehicle internal combustion engine according to claim 1, wherein the amount of power generated by said generator is temporarily reduced when the engine transitions from a lock-up state to a non-lock-up state.

3. The vehicle is equipped with a continuously variable transmission as the transmission, determining whether the location is at high altitude based on atmospheric pressure; 3. A method for controlling a negative pressure in an internal combustion engine for a vehicle according to claim 1, wherein, when the vehicle is at high altitude, the gear ratio of the transmission during deceleration in a lockup state where the accelerator opening is equivalent to a fully closed state is corrected to be relatively larger than when the vehicle is at low altitude.

4. an internal combustion engine having a throttle valve; a vacuum-type brake booster that uses the intake negative pressure downstream of the throttle valve as a negative pressure source; a torque converter provided between the internal combustion engine and the transmission and equipped with a lock-up clutch; a generator as an auxiliary machine driven by the output of the internal combustion engine; A controller; Equipped with The above controller is When the vehicle is decelerating and the accelerator opening is equivalent to a fully closed position, fuel is cut off in accordance with predetermined fuel cut conditions, and the lock-up clutch is controlled to either a lock-up state or a non-lock-up state in accordance with predetermined lock-up conditions. The command voltage of the generator is controlled to be higher than the command voltage during normal driving when the vehicle is decelerating in a lockup state, a normal correction air amount is calculated in accordance with an accessory drive torque required to drive the generator, and when the vehicle is decelerating during normal running or in a non-lockup state, the normal correction air amount is used as an additional amount for the accessory to control the intake air amount of the internal combustion engine via the throttle valve; During deceleration in a lockup state, a constant decrease correction air amount, which is relatively smaller than the normal correction air amount and is unrelated to the accessory drive torque, is used as an increase air amount for the accessory, and the intake air amount of the internal combustion engine is controlled via the throttle valve. A vacuum control device for a vehicle internal combustion engine.

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