JP3707277B2 - Automatic stop / start device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic stop / start technology for an internal combustion engine that automatically stops and starts an internal combustion engine mounted on an automobile or the like when a predetermined condition is satisfied.
[0002]
[Prior art]
In recent years, for the purpose of reducing fuel consumption, exhaust emission, or noise of internal combustion engines mounted on automobiles, etc., the operation of the internal combustion engine is automatically stopped when the vehicle stops, such as waiting for a signal, and the internal combustion engine is started when the vehicle starts. Development of an automatic stop / start device that automatically starts the engine is in progress.
[0003]
In such an automatic stop / start device, the internal combustion engine needs to be reliably started at the restart after the automatic stop, but the internal combustion engine is started by a starter motor that operates with electric power stored in a power storage device such as a battery. For this reason, when it becomes impossible to output sufficient electric power to operate the starter motor due to insufficient storage capacity or deterioration of the power storage device, it is difficult to reliably start the internal combustion engine.
[0004]
Conventionally, with respect to such a problem, the output voltage of the battery is less than a predetermined voltage even when the automatic stop condition is satisfied, as in the “engine automatic stop / start device” described in JP-A-58-25864. In some cases, a technique for prohibiting automatic stop control of an internal combustion engine has been proposed.
[0005]
[Problems to be solved by the invention]
By the way, in the automatic stop / start device as described above, when the internal combustion engine is prohibited from being automatically stopped and the internal combustion engine is in an idle operation state, the power generation amount of the power generator increases to compensate for the decrease in the output voltage of the battery. Therefore, there is a problem that the load of the internal combustion engine related to the operation of the power generation device increases, the fuel consumption rate of the internal combustion engine deteriorates, and the original effect of the automatic stop / start device is impaired.
[0006]
The present invention has been made in view of the above problems, and is an apparatus that automatically stops and restarts an internal combustion engine when a predetermined condition is satisfied, and performs automatic stop and start control when the function of the power storage device is reduced. An object of the present invention is to provide a technology for preventing deterioration of the fuel consumption rate of an internal combustion engine when automatic stop control is prohibited in a prohibited device.
[0007]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. That is, an internal combustion engine automatic stop / start apparatus according to the present invention includes a power generation unit that generates power using the output of the internal combustion engine, and a power storage unit that stores part or all of the power generated by the power generation unit. Automatic stop / start means for automatically stopping and starting the internal combustion engine when a predetermined condition is satisfied; and when the predetermined condition is satisfied and the power storage function of the power storage means is reduced, the automatic stop / start means Automatic stop / start prohibiting means for prohibiting automatic stop / start control and when automatic stop / start control is prohibited by the automatic stop / start prohibiting means when the internal combustion engine is in an idling state , characterized by comprising a power generation amount control means lack causes decrease the output of the generator means to the extent that can cover the electric load of a vehicle equipped with the internal combustion engine.
[0008]
In the automatic stop / start device for an internal combustion engine configured as described above, the automatic stop / start means operates the internal combustion engine when the automatic stop condition is satisfied and the power storage function of the power storage means has not deteriorated. Stop automatically.
[0009]
Thereafter, when the automatic start condition is satisfied, the automatic stop / start means automatically starts the internal combustion engine using the electric power stored in the power storage means. Then, after the start of the internal combustion engine is completed, the power generated by the power generation means is supplied to the power storage means in order to supplement the power taken out from the power storage means when the internal combustion engine is automatically stopped or the power taken out from the power storage means during the automatic start. Accumulated.
[0010]
On the other hand, the automatic stop / start prohibiting means prohibits the automatic stop / start control by the automatic stop / starting means when detecting that the power storage function of the power storage means is lowered when the automatic stop condition is satisfied.
[0011]
The power generation amount control means can cover the electric load of the vehicle equipped with the internal combustion engine when the automatic stop / start control is prohibited by the automatic stop / start prohibition means and the internal combustion engine is in an idle operation state. lack causes decrease the output of the generator means at the inner.
[0012]
In this case, when the automatic stop / start control is prohibited and the internal combustion engine is in an idle operation state, the load on the internal combustion engine related to the operation of the power generation means is reduced, and the fuel consumption of the internal combustion engine is suppressed. Is done.
[0013]
As a result, when the automatic stop / start control is prohibited and the internal combustion engine is in an idle operation state, the deterioration of the fuel consumption rate of the internal combustion engine due to the deterioration of the power storage function of the power storage means is suppressed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a specific embodiment of an automatic stop / start device for an internal combustion engine according to the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an automatic stop / start device according to the present invention is applied.
An internal combustion engine 1 shown in FIG. 1 is a multi-cylinder water-cooled gasoline engine having a plurality of cylinders. The internal combustion engine 1 is connected to a transmission (T / M) 200 via a clutch mechanism (or torque converter) 100. The transmission (T / M) 200 is connected to a propeller shaft, a differential gear, etc. (not shown). It is connected to the driving wheel.
[0016]
In the power transmission system configured as described above, when the clutch mechanism 100 is in the engaged state, the rotational force of the output shaft (crankshaft) (not shown) of the internal combustion engine 1 is transmitted via the clutch mechanism 100 to the transmission (T / M). ) 200, and is decelerated or accelerated by the transmission (T / M) 200, and then transmitted from the transmission (T / M) 200 to the drive wheels via a propeller shaft, a differential gear, and the like.
[0017]
Next, an intake branch pipe 2 is connected to the internal combustion engine 1, and each branch pipe of the intake branch pipe 2 communicates with a combustion chamber (not shown) of each cylinder via an intake port. The intake branch pipe 2 is connected to a surge tank 3, and the surge tank 3 communicates with an air cleaner box 5 via an intake pipe 4.
[0018]
In the intake system configured as described above, fresh air taken into the air cleaner box 5 is supplied to the surge tank 3 through the intake pipe 4, and then distributed from the surge tank 3 to each branch pipe of the intake branch pipe 2. Supplied to the combustion chamber of the cylinder.
[0019]
An air flow meter 6 that outputs an electric signal corresponding to the mass of fresh air flowing in the intake pipe 4 is attached in the middle of the intake pipe 4, and the surge tank 3 has an electric flow corresponding to the pressure in the surge tank 3. A vacuum sensor 12 for outputting a signal is attached.
[0020]
The intake pipe 4 downstream of the air flow meter 6 is provided with a throttle valve 7 that adjusts the flow rate of fresh air flowing through the intake pipe 4. The throttle valve 7 comprises a stepper motor or the like, and includes an actuator 8 that opens and closes the throttle valve 7 according to the magnitude of the applied current, and a throttle position sensor 9 that outputs an electrical signal according to the opening of the throttle valve 7. And are attached.
[0021]
Subsequently, an accelerator lever (not shown) that rotates in conjunction with an accelerator pedal 10 installed in the passenger compartment is attached to the throttle valve 7, and the accelerator lever corresponds to the amount of rotation of the accelerator lever. An accelerator position sensor 11 that outputs an electrical signal (an electrical signal corresponding to the amount of depression of the accelerator pedal 10) is attached.
[0022]
Fuel injection valves 13a, 13b, 13c, and 13d (hereinafter collectively referred to as fuel injection valves 13) are attached to the branch pipes of the intake branch pipe 2 so that the injection holes face the intake ports. A fuel distribution pipe 14 is connected to these fuel injection valves 13, and the fuel distribution pipe 14 is connected to a fuel pump (not shown).
[0023]
Connected to each fuel injection valve 13 is a drive circuit 15a, 15b, 15c, 15d (hereinafter collectively referred to as drive circuit 15) that drives the fuel injection valve 13 to open.
In the fuel injection system configured as described above, the fuel discharged from the fuel pump is supplied to the fuel distribution pipe 14 and then distributed from the fuel distribution pipe 14 to each fuel injection valve 13. When a drive current is applied from the drive circuit 15 to the fuel injection valve 13, the fuel injection valve 13 is opened and the fuel supplied from the fuel distribution pipe 14 is injected into the intake port.
[0024]
On the other hand, an exhaust branch pipe 16 is connected to the internal combustion engine 1, and each branch pipe of the exhaust branch pipe 16 communicates with a combustion chamber of each cylinder through an exhaust port (not shown). The exhaust branch pipe 16 is connected to an exhaust pipe 17, and the exhaust pipe 17 is connected to a muffler (not shown) downstream.
[0025]
An exhaust purification catalyst 18 that purifies harmful gas components such as CO, NO _x , and HC contained in the exhaust discharged from the internal combustion engine 1 is provided in the middle of the exhaust pipe 17. As the exhaust purification catalyst 18 can be exemplified three-way catalyst, oxidation catalyst, a selective reduction type NO _X catalyst or a storage reduction NO _X catalyst.
[0026]
An air-fuel ratio sensor 19 that outputs a current corresponding to the air-fuel ratio of the exhaust flowing in the exhaust pipe 17 is attached to the exhaust pipe 17 upstream of the exhaust purification catalyst 18.
Next, each time the crankshaft (not shown) rotates a predetermined angle (for example, 10 degrees), the internal combustion engine 1 has a crank position 20 that outputs a pulse signal, and a water temperature that outputs an electric signal corresponding to the temperature of the engine cooling water. A sensor 21 is attached.
[0027]
Further, the internal combustion engine 1 or the clutch mechanism 100 is provided with a starter motor 300 having a pinion gear that meshes with a ring gear provided on the circumference of a flywheel (or drive wheel) (not shown) attached to the tip of the crankshaft. ing. The starter motor 300 operates with the battery 500 serving as a power storage unit as a drive source when the internal combustion engine 1 is started, and the rotational force of the starter motor 300 at that time is transmitted to the crankshaft via the pinion gear and the flywheel. Institution 1 is cranked.
[0028]
Further, the internal combustion engine 1 is provided with a power generation mechanism 400 connected to a crank pulley (not shown) attached to the base end of the crankshaft via a belt. The power generation mechanism 400 realizes power generation means according to the present invention, and includes, for example, an alternator 401, a regulator 402, and a controller 403 as shown in FIG.
[0029]
The alternator 401 includes a diode rectifier 404, a stator 405, and a rotor coil 406 that rotates in response to the rotational force of the crankshaft. When an excitation current is applied to the rotor coil 406, the rotor coil 406 generates a magnetic flux. The three-phase alternating current is induced in the stator 405.
[0030]
The three-phase alternating current generated in the stator 405 is converted into direct current by the diode rectifier 404 and output from the alternator 401. The DC voltage output from the alternator 401 is applied to the ignition of the internal combustion engine 1, a vehicle electric load 407 such as a lighting device, an air conditioner, or an audio device mounted on the vehicle, or the battery 500.
[0031]
The regulator 402 includes a switching transistor 402a that switches between electrical conduction and interruption between the battery 500 and the rotor coil 406, and a drive circuit 402b that drives the switching transistor 402a on and off.
[0032]
The controller 403 is connected to the drive circuit 402b through electrical wiring, and controls the on / off of the switching transistor 402a by transmitting a drive signal to the drive circuit 402b.
[0033]
At that time, the controller 403 senses the voltage: VB output from the alternator 401 and controls the regulator 402 to adjust the exciting current of the rotor coil 406 so that the output voltage: VB becomes a desired voltage.
[0034]
Returning to FIG. 1, the internal combustion engine 1 is provided with an electronic control unit (ECU) 22 for engine control. In addition to the air flow meter 6, throttle position sensor 9, accelerator position sensor 11, vacuum sensor 12, air-fuel ratio sensor 19, crank position sensor 20, water temperature sensor 21, and power generation mechanism 400, the ECU 22 is installed in the vehicle interior. A shift position sensor 23 for detecting the position of the shift lever, a brake switch 24 for detecting operation / non-operation of the brake pedal, a vehicle speed sensor 25 for detecting the traveling speed of the vehicle, the discharge current amount and the charge current amount of the battery 500. Various sensors such as the SOC controller 28 for calculating the state of charge of the battery 500 from the integrated value are connected via electric wiring, and output signals of the various sensors are input to the ECU 22. Further, an on / off signal for the starter switch 26 and an on / off signal for the ignition switch 27 are input to the ECU 22.
[0035]
On the other hand, the actuator 8, the drive circuit 15, the starter motor 300, the power generation mechanism 400, and the like are connected to the ECU 22 via electrical wiring. The ECU 22 uses the output signals of the various sensors described above as parameters and the actuator 8 and the drive circuit 15. The control signal can be transmitted to the starter motor 300, the power generation mechanism 400, or the like.
[0036]
Here, as shown in FIG. 3, the ECU 22 includes a CPU 29, a ROM 30, a RAM 31, and a backup RAM 32 that are connected to each other via a bidirectional bus 37. A first input interface circuit 33 is connected to the bidirectional bus 37 via an A / D converter 36, and a second input interface circuit 34 and an output interface circuit 35 are connected to the bidirectional bus 37.
[0037]
The first input interface circuit 33 is connected to the air flow meter 6, the throttle position sensor 9, the accelerator position sensor 11, the vacuum sensor 12, the water temperature sensor 21, the air-fuel ratio sensor 19, the SOC controller 28, and the power generation mechanism 400 through electric wiring. Then, an output signal of each sensor and an output voltage: VB of the power generation mechanism 400 are input, and these signals are input to the A / D converter 36.
[0038]
The A / D converter 36 converts various signals input from the first input interface circuit 33 from an analog signal format to a digital signal format, and then transmits the signals to the CPU 29 and the RAM 31 via the bidirectional bus 37.
[0039]
The second input interface circuit 34 is connected to the crank position sensor 20, the shift position sensor 23, the brake switch 24, the vehicle speed sensor 25, the starter switch 26, and the ignition switch 27 through electric wiring, and inputs output signals from the sensors. Then, these output signals are transmitted to the CPU 29 and the RAM 31 via the bidirectional bus 37.
[0040]
The output interface circuit 35 is connected to the actuator 8, the drive circuit 15, the starter motor 300, and the controller 403 of the power generation mechanism 400 through electrical wiring, and the actuator 8 and drive circuit described above for various control signals output from the CPU 29. 15, the data is transmitted to the starter motor 300 or the controller 403 of the power generation mechanism 400.
[0041]
The ROM 30 is a fuel injection amount control routine for determining the fuel injection amount to be injected from each fuel injection valve 13, a fuel injection timing control routine for determining the timing for injecting fuel from each fuel injection valve 13, and each cylinder. Various application programs such as an ignition timing control routine for determining the ignition timing of the engine, a throttle opening degree control routine for determining the opening degree of the throttle valve 7, and various control maps are stored.
[0042]
The control map stored in the ROM 30 is, for example, a fuel injection amount control map showing the relationship between the operating state of the internal combustion engine 1 and the fuel injection amount, and the fuel injection showing the relationship between the operating state of the internal combustion engine 1 and the fuel injection timing. A timing control map, an ignition timing control map showing the relationship between the operating state of the internal combustion engine 1 and the ignition timing, an amount of depression of the accelerator pedal 10 (accelerator opening) and a target opening of the throttle valve 7 (target throttle opening) It is a throttle opening degree control map etc. which show a relationship.
[0043]
The RAM 31 stores output signals from the sensors, calculation results of the CPU 29, and the like. The calculation result is, for example, the engine speed calculated based on the output signal of the crank position sensor 20. The output signal from each sensor, the calculation result of the CPU 29, and the like are updated to the latest data every time the crank position sensor 20 outputs a pulse signal.
[0044]
The backup RAM 32 is a non-volatile memory that retains data even after the engine is stopped.
The CPU 29 operates in accordance with an application program stored in the ROM 30 and executes fuel injection control, ignition control, throttle control, and the like using output signals of various sensors as parameters, and also performs automatic stop / start control as the gist of the present invention. To do.
[0045]
In the automatic stop / start control, the CPU 29 executes an automatic stop / start control routine as shown in FIG. This automatic stop / start control routine is a routine that is repeatedly executed at predetermined time intervals (for example, every time the crank position sensor 20 outputs a pulse signal) when the ignition switch 23 is in an ON state.
[0046]
In the automatic stop / start control routine, the CPU 29 determines whether or not an automatic stop condition for the internal combustion engine 1 is satisfied in S401. As the automatic stop condition, for example, the output signal value (vehicle speed) of the vehicle speed sensor 25 is “0”, and the output signal value of the shift position sensor 23 is a signal indicating “neutral position”. For example, the engine speed calculated based on the signal value is equal to or less than a predetermined speed, and the output signal value of the accelerator position sensor 11 is a signal indicating “accelerator fully closed”.
[0047]
If it is determined in S401 that the automatic stop condition is not satisfied, the CPU 29 once ends the execution of this routine.
On the other hand, if it is determined in S401 that the automatic stop condition is satisfied, the CPU 29 proceeds to S402 and determines whether or not the output signal value of the SOC controller 28 is equal to or greater than a predetermined reference value.
[0048]
If it is determined in S402 that the output signal value of the SOC controller 28 is greater than or equal to a predetermined reference value, the CPU 29 proceeds to S407, executes automatic stop control of the internal combustion engine 1, and temporarily terminates execution of this routine. . In the automatic stop control, the CPU 29 controls the actuator 8 so as to stop the supply of drive power from the drive circuit 15 to the fuel injection valve 13, for example, so-called fuel cut control, or to fully close the throttle valve 7. Then, the operation of the internal combustion engine 1 is stopped.
[0049]
If it is determined in S402 that the output signal value of the SOC controller 28 is less than the predetermined reference value, the CPU 29 proceeds to S404 and determines whether or not the internal combustion engine 1 is in an idling operation state. Specifically, the CPU 29 determines whether or not the output signal value of the accelerator position sensor 11 indicates “accelerator pedal fully closed state” and the engine speed is equal to or lower than a predetermined speed.
[0050]
If it is determined in S404 that the internal combustion engine 1 is in the idling operation state, the CPU 29 executes power generation voltage suppression control in S405, and temporarily ends the execution of this routine. In the power generation voltage suppression control, the CPU 29 controls the regulator 402 via the controller 403 of the power generation mechanism 400, for example, thereby setting the excitation current applied to the rotor coil 406 of the alternator 401 to a predetermined current value. The induced three-phase AC voltage (that is, the generated voltage of the alternator 401) is reduced to a predetermined voltage.
[0051]
As described above, the predetermined current value applied to the rotor coil 406 is a value set so that the power generation voltage of the alternator 401 becomes a minimum voltage that can cover the operation of the vehicle electrical load 407, and is obtained experimentally in advance. It may be a fixed value, or may be a variable value that is changed according to the state of charge of the battery 500 or the size of the vehicle electrical load 407.
[0052]
On the other hand, if it is determined in S404 that the internal combustion engine 1 is not in the idle operation state, the CPU 29 responds to the engine operation state in order to supplement the power of the battery 500 consumed during the automatic stop control of the internal combustion engine 1 in S406. The power generation control is executed, and the execution of this routine is once ended.
[0053]
In the power generation control, for example, as shown in FIG. 5, when the engine speed is low and the accelerator opening is small, the CPU 29 reduces the power generation voltage of the alternator 401 to minimize the charging voltage to the battery 500. The minimum voltage that can cover the operation of the vehicle electrical load 407 is ensured. When the engine speed is high or the accelerator opening is large, the influence on the fuel consumption rate and the exhaust amount discharged from the internal combustion engine 1 due to the operation of the alternator 401 becomes small. The power generation voltage is increased to ensure a sufficient charging voltage for the battery 500, while ensuring a voltage that can cover the operation of the vehicle electrical load 407.
[0054]
In the power generation control, as shown in FIG. 6, the CPU 29 may perform control so that the power generation voltage of the alternator 401 decreases as the accelerator opening increases in the operation region where the engine speed is low. According to such power generation control, when shifting from the low load operation region to the high load operation region as in acceleration, i.e., when the accelerator opening becomes large with the engine speed being low, the engine speed is Since the power generation voltage is suppressed while the value is low, the engine output consumed for the operation of the alternator 401 is reduced, so that drivability can be improved.
[0055]
As described above, the CPU 29 executes the automatic stop / start control routine, thereby realizing the automatic stop / start means, the automatic stop / start prohibiting means, and the power generation amount control means according to the present invention.
[0056]
Therefore, according to the above-described embodiment, in the internal combustion engine 1 equipped with the automatic stop / start device, when the automatic stop control is prohibited and the internal combustion engine 1 enters the idle operation state, the operation amount of the alternator 401 is reduced. Since the engine load associated with the operation of the alternator 401 is prevented to a minimum, the fuel consumption rate of the internal combustion engine 1 is prevented from deteriorating and the exhaust emission amount is prevented from increasing, and the fuel consumption rate of the automatic stop / start device is reduced. It is possible to always keep the effects of improvement and reduction of exhaust emissions to the maximum.
[0058]
Further, in the present embodiment, a single battery has been described as an example of the power storage unit according to the present invention. However, as illustrated in FIGS. 7 and 8, the main battery 501 and the sub battery having different output voltages are used. A configuration in which 502 is combined with the power converter 503 may be used. At this time, the main battery 501 and / or the sub-battery 502 may be configured by connecting a single battery or a plurality of electric double-phase capacitors or the like that accompany a chemical change such as a lead storage battery.
[0059]
When such a configuration is adopted, in the generated voltage suppression control, the CPU 29 may stop the operation of the power converter 503 so that the main battery 501 and / or the sub battery 502 are not charged.
[0060]
【The invention's effect】
In the automatic stop / start device according to the present invention, when the automatic stop / start control of the internal combustion engine is prohibited, if the internal combustion engine is in an idle operation state, it is within a range that can cover the electric load of the vehicle on which the internal combustion engine is mounted. since the output of the power generator is reduced little of the load of the internal combustion engine according to the operation of the power generator is reduced, deterioration and increase in emissions of exhaust fuel consumption rate of the internal combustion engine is suppressed.
[0061]
Therefore, according to the present invention, in an internal combustion engine equipped with an automatic stop / start device, even when the automatic stop control is prohibited, the fuel consumption rate is improved and the exhaust gas, which is the original effect of the automatic stop / start device, is exhausted. It is possible to always maximize the reduction of emissions.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an automatic stop / start device according to the present invention is applied. FIG. 2 is a diagram showing an internal configuration of a power generation mechanism. FIG. 3 is a diagram showing an internal configuration of an ECU. FIG. 5 is a flowchart showing an automatic stop / start control routine in the embodiment. FIG. 5 is a diagram for explaining power generation control of an alternator (1).
FIG. 6 is a diagram for explaining power generation control of the alternator (2).
FIG. 7 is a diagram showing another embodiment of a battery (1)
FIG. 8 is a diagram showing another embodiment of a battery (2)
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ...... Internal combustion engine 7 ... Throttle valve 10 ... Accelerator pedal 11 ... Accelerator position sensor 20 ... Crank position sensor 21 ... Water temperature sensor 22 ... ECU
29 ... CPU
30 ... ROM
300. Starter motor 400 Power generation mechanism 401 Alternator 402 Regulator 403 Controller 407 Electric load 500 Battery

Claims (1)

Power generation means for generating power using the output of the internal combustion engine;
Power storage means for storing part or all of the power generated by the power generation means ;
Automatic stop / start means for automatically stopping and automatically starting the internal combustion engine when a predetermined condition is satisfied;
Automatic stop / start prohibiting means for prohibiting automatic stop / start control by the automatic stop / start means when the predetermined condition is satisfied and the power storage function of the power storage means is reduced;
When automatic stop / start control is prohibited by the automatic stop / start prohibiting means, and when the internal combustion engine is in an idle operation state, within a range that can cover the electric load of the vehicle on which the internal combustion engine is mounted. a power generation amount control means causing reduced less of the output of the generator means,
An automatic stop / start device for an internal combustion engine.

Images