JP2014177908A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure that a larger amount of negative pressure can be supplied by a brake booster for a period of time immediately after a startup of an internal combustion engine.SOLUTION: A voltage of a battery to be charged by a generator is controlled to be a first target value for a period of time immediately after a startup of an internal combustion engine and thereafter is controlled to be a second target value higher than the first target value. On that basis, transition of the target value of the voltage of the battery from the first target value to the second target value is adjusted so that an index value of the degree of output of the generator is prevented from overshooting a predetermined value or more, for a transition period for transiting from the first target value to the second target value.

Description

  The present invention relates to an internal combustion engine mounted on a vehicle and a control device that controls a generator that generates electric power by receiving a rotational driving force transmitted from the internal combustion engine.

  In general, in a vehicle equipped with an internal combustion engine, a part of the output torque of the internal combustion engine is supplied to a generator to generate electric power, and the generated electric power is supplied to the electrical system of the vehicle, and an in-vehicle battery is charged. ing.

  The IC regulator associated with the generator operates the output voltage of the generator by increasing or decreasing the DUTY ratio (fDUTY) of the current flowing through the field coil so that the terminal voltage of the battery follows the target value. The target value of the battery voltage is commanded from an ECU (Electronic Control Unit) that controls the internal combustion engine and the generator.

  The generator during power generation becomes a mechanical load on the internal combustion engine. The load increases as the output voltage of the generator increases, in other words, as the fDUTY in the generator increases.

  Immediately after starting the internal combustion engine, the engine temperature is low and the viscosity of the lubricating oil is high, so the engine rotation tends to become unstable. Therefore, the target value of the initial battery voltage is suppressed to a relatively low value (for example, about 13 V), and the load caused by the generator is reduced to prevent engine stall. Then, after a certain amount of time has elapsed since the start of the internal combustion engine (for example, about 90 seconds from the start), the target value of the battery voltage is raised to the original value (for example, about 14.5 V) (see the following patent document). .

  The above-described control is also effective for securing the intake negative pressure to be supplied to the brake booster. While the internal combustion engine is stopped, the battery is discharged and its voltage decreases. If the target value of the battery voltage is set high immediately after the start of the internal combustion engine, the amount of power generated by the generator increases accordingly. When the power generation amount, that is, fDUTY increases, it is necessary to increase and correct the intake amount (and fuel injection amount) charged in the cylinder to increase the output torque of the engine, and the intake negative pressure generated downstream of the throttle valve decreases. To do. If the target value of the battery voltage immediately after starting the internal combustion engine is set low, the negative pressure that can be supplied to the brake booster increases.

  However, even with the above-described control, a sufficient amount of negative pressure may not be accumulated in the brake booster. If the fDUTY of the generator overshoots during the transition period when the target value of the battery voltage is raised from the lower value to the original value, the intake amount corrected according to fDUTY also overshoots, and the intake negative pressure is reduced at that time. Decrease. As a result, there is a concern that the brake booster negative pressure is insufficient.

JP 2012-072664 A

  An object of the present invention is to make it possible to supply a large amount of negative pressure to the brake booster immediately after the start of the internal combustion engine.

  The present invention controls an internal combustion engine mounted on a vehicle and a generator that generates electric power by receiving transmission of rotational driving force from the internal combustion engine, and is charged by the generator immediately after the start of the internal combustion engine. The battery voltage is controlled to the first target value, and then controlled to the second target value higher than the first target value. In the transition period in which the first target value transitions to the second target value, the generator The control device is characterized in that the transition of the target value of the battery voltage from the first target value toward the second target value is adjusted so that the index value of the output level does not overshoot more than a predetermined value.

  The transition of the target value of the battery voltage from the first target value to the second target value is changed according to the length of the period from the start of the internal combustion engine to the time when the battery voltage reaches the first target value. Is preferred.

  According to the present invention, it is possible to supply a large amount of negative pressure to the brake booster at a time immediately after starting the internal combustion engine.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The figure which shows the electric circuit for controlling the various electric loads mounted in the vehicle. The timing diagram explaining the content of the control which the control apparatus of the embodiment performs.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type 4-stroke gasoline engine, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  The brake booster 5 introduces intake negative pressure from a portion of the intake passage 3 downstream of the throttle valve 32 (surge tank 33 or intake manifold 34), and boosts the pedal effort of the brake pedal using the negative pressure. It is widely known in the field. The brake booster 5 has a constant pressure chamber for storing negative pressure and a variable pressure chamber for applying atmospheric pressure, and the constant pressure chamber is connected to the surge tank 33 via the negative pressure line 51. The negative pressure line 51 guides the intake negative pressure downstream of the throttle valve 32 to the constant pressure chamber. A check valve 52 is provided on the negative pressure line 51 to keep the negative pressure in the constant pressure chamber and prevent the positive pressure from being applied to the constant pressure chamber.

  When the brake pedal is not operated by the driver, the constant pressure chamber and the variable pressure chamber communicate with each other, and the variable pressure chamber is isolated from the atmospheric pressure. When the brake pedal is operated, the constant pressure chamber and the variable pressure chamber are interrupted, and the atmosphere is introduced into the variable pressure chamber. As a result, the pressure difference between the constant pressure chamber and the variable pressure chamber becomes a control pressure that boosts the depression force of the brake pedal. The brake pedal force amplified by the brake booster 5 is converted into hydraulic pressure in a master cylinder (not shown), and is supplied to a brake device (not shown) such as a brake caliper and a wheel cylinder via a hydraulic circuit (not shown). Communicated.

  Various electric loads are mounted on the vehicle. Specific examples include air conditioner blowers, rear glass defoggers, audio equipment, car navigation systems, lighting (headlamps, taillights, fog lights, turn signals (turn signal lamps), etc.), internal combustion engines A radiator fan that cools cooling water, an electric power steering device, and the like can be given.

  A refrigerant compression compressor of an air conditioner is rotationally driven in response to transmission of a rotational driving force from a crankshaft of an internal combustion engine, and compresses the refrigerant. As shown in FIG. 2, a magnet clutch 61 that can be connected and disconnected is interposed between the compressor and the crankshaft. When operating the air conditioner, the magnet clutch 61 is energized with a current from the battery 62 and / or the generator 63 mounted on the vehicle, and the magnet clutch 61 is engaged. On the contrary, when the air conditioner is not operated, the magnet clutch 61 is not energized and the clutch 61 is disconnected. Energization and disconnection of the magnet clutch 61 is performed by turning ON / OFF the relay switch 64.

  The motor 66 that rotationally drives the blower for blower and the heating wire heater 68 laid on the rear glass as a defogger operate by receiving power supply from the battery 62 and / or the generator 63. Energization and interruption of the motor 66 and the heater 68 are performed by turning on / off the relay switch 67 or starting / extinguishing a semiconductor switching element (power device represented by a power transistor, power MOSFET, etc.) 69.

  Audio devices, car navigation systems, illumination lights, motors for rotating the radiator fan, and other electrical loads are the same as described above.

  A generator (alternator or motor generator) 63, which is a source of power supply to the electric load, is rotated by receiving a rotational driving force from the crankshaft of the internal combustion engine and generates electric power. The generator 63 is connected to the crankshaft via a winding transmission mechanism having a belt and a pulley as elements. The generator 63 may perform regenerative power generation. In other words, when the driver does not step on the accelerator pedal and does not require acceleration of the vehicle (accepts deceleration), the energy of rotation of the crankshaft and axle is converted into electric energy and recovered. , Decelerate the internal combustion engine and the vehicle.

  The magnitude of the voltage generated and output by the generator 63 can be controlled via the regulator 65. The regulator 65 is a known IC type attached to the generator 63, and performs a switching operation for switching ON / OFF the energization of the field coil of the generator 63.

  The output voltage of the generator 63, that is, the voltage induced in the stator coil of the generator 63 increases in proportion to fDUTY, which is the DUTY ratio of the field current flowing through the field coil. The regulator 65 receives a signal r for instructing the output voltage of the generator 63 from the ECU 0, and performs PWM control for adjusting fDUTY so as to realize the instructed output voltage. With this PWM control, the power generated by the generator 63 can be increased or decreased. The amount of power generated by the generator 63, in other words, the amount of charge to the battery 62 and / or the amount of power supplied to the electrical load increases as fDUTY increases and decreases as fDUTY decreases.

  The generator 63 becomes a mechanical load when viewed from the internal combustion engine. When the output voltage of the generator 63 exceeds the terminal voltage of the battery 62, the battery 62 is charged and electric power is supplied from the generator 63 to the electric load. That is, the generator 63 works to generate electric energy by consuming energy of rotation of the crankshaft. The amount of charge to the battery 62 and the amount of power supplied to the electric load depend on the potential difference between the output voltage of the generator 63 and the battery 62 voltage.

  Conversely, when the output voltage of the generator 63 is less than or close to the battery 62 voltage, the battery 62 is not charged, and no power is supplied from the generator 63 to the electric load (the electric load from the battery 62). May be powered). In other words, the generator 63 does not do work that consumes the energy of rotation of the crankshaft, or the work becomes small.

  In short, when a high output voltage is commanded from the ECU 0 to the regulator 65, the mechanical load of the generator 63 with respect to engine rotation increases, and when a low output voltage is commanded, the mechanical load of the generator 63 with respect to engine rotation decreases.

  The ECU 0 as the control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. The accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (so-called required load), the intake air temperature and the intake pressure in the intake passage 3 (particularly, the surge tank 33). An intake air temperature / intake pressure signal d output from a temperature / pressure sensor to be detected, a cooling water temperature signal e output from a water temperature sensor for detecting engine cooling water temperature, and output from a sensor for detecting a terminal current and terminal voltage of the battery 62 Output from the sensor that detects the battery state signal f and the negative pressure stored in the constant pressure chamber of the brake booster 5 Brake booster negative pressure signal g, signal h indicating the magnitude of fDUTY output from the regulator 65 attached to the generator 63, and an operation request regarding whether or not to operate each of the air conditioner and various electric loads A signal m, a refrigerant pressure signal n output from a refrigerant pressure sensor that detects the pressure of the refrigerant flowing down from the condenser of the air conditioner, and the like are input. The operation request signal m is manually issued from an operation switch (or control panel) for each air conditioner or electric load, which is manually operated by a driver or passenger who desires to operate the air conditioner and various electric loads. It may be a control signal or an automatic control signal issued from an auto air conditioner ECU that controls the auto air conditioner system.

  From the output interface, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and a switch on the electric circuit for energizing the magnet clutch 61 64, the clutch engagement signal o, the motor 66, the heater 68, and other switches 67, 69 on the electric circuit for energizing the electric load, the switch ON signals p, q, the voltage for controlling the voltage generated by the generator 63. A voltage instruction signal r or the like is output to the regulator 65.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 obtains various information a, b, c, d, e, f, g, h, m, n necessary for operation control of the internal combustion engine via the input interface, and knows the engine speed and also uses the cylinder 1 Estimate the amount of intake air to be filled. Based on the engine speed and intake air amount, the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, ON / OFF of the compressor of the air conditioner Various operation parameters such as OFF, blower ON / OFF, defogger ON / OFF, various other electric loads, and output voltage (power generation amount) of the generator 63 are determined. The ECU 0 applies various control signals i, j, k, o, p, q, r corresponding to the operation parameters via the output interface.

  In addition, the ECU 0 inputs a control signal s to the electric motor (starter motor or motor generator) when the internal combustion engine is started (a cold start or a return from an idling stop). Cranking is performed by rotating the crankshaft. Cranking ends when the internal combustion engine starts from the first explosion to a continuous explosion and the engine speed, that is, the rotation speed of the crankshaft, exceeds a judgment value determined according to the coolant temperature, etc. (assuming that the explosion has been completed) To do.

  Thus, the ECU 0 of the present embodiment controls the voltage of the battery 62 charged by the generator 63 to the first target value at the time immediately after the start of the internal combustion engine, and then the second target higher than the first target value. Control to value.

  FIG. 3 illustrates the transition of the battery 62 voltage after the start of the internal combustion engine, the fDUTY of the generator 63, the correction amount of the intake amount charged in the cylinder 1, and the intake pressure in the surge tank 33.

  The first target value, which is the initial target value of the battery 62 voltage, is about 13V, for example. This value is lower than the terminal voltage of the battery 62 in a fully charged state (close to full charge).

  The second target value, which is the target value of the voltage of the battery 62 after a lapse of time from the start of the internal combustion engine, is about 14.5 V, for example. This value is approximately equal to the terminal voltage of the battery 62 in a fully charged state. The second target value is also a normal target value during operation of the internal combustion engine.

The ECU ₀ keeps the target voltage command r to be applied to the regulator 65 at the first target value until a predetermined time, for example, about 90 seconds elapses from the starting time t ₀ of the internal combustion engine. Then, the target voltage command r to be supplied to the regulator 65 is changed toward the second target value from the time point t ₂ when the time has elapsed.

In FIG. 3, the curve indicated by a broken line is a transition by conventional control. In the conventional control, the target voltage command r given to the regulator 65 is rapidly raised from the first target value to the second target value after time t ₂ .

As a result, after time t ₂ , fDUTY indicating the output level of the generator 63 overshoots. The ECU 0 corrects the intake air amount (and the fuel injection amount) by increasing or decreasing the opening of the throttle valve 32 so as to increase or decrease the output torque of the internal combustion engine so as to correspond to the increase or decrease of fDUTY. Therefore, the overshoot of fDUTY causes an overshoot of the intake amount and the intake pressure, and the intake negative pressure ΔP ′ that can be supplied to the brake booster 5 after the time t ₂ is reduced.

On the other hand, a straight line represented by a solid line in FIG. 3 is a transition by the control of the present embodiment. In the present embodiment, the target voltage command r given to the regulator 65 after the time point t ₂ is more slowly increased toward the second target value, that is, the unit time of the target value of the battery 62 voltage, as compared with the conventional control. The amount of increase per unit is less (the rate of increase is slower).

This makes it possible to time t ₂ after the F duty, the intake amount and the intake pressure does not overshoot, reserving much more deliverable intake negative pressure ΔP to the brake booster 5 after time t _2.

The transition of the target voltage command r applied to the regulator 65 after time t ₂ is the period from the start time t ₀ of the internal combustion engine to the time t ₁ when the battery 62 voltage reaches the first target value, and / or the simultaneous point t. It changes according to the maximum value P of fDUTY that appears immediately after ₁ .

The length of the period from the time point t ₀ to the time point t ₁ and the magnitude of the maximum value P are the amount of charge of the battery 62 when the internal combustion engine is started (the amount of discharge of the battery 62 when the internal combustion engine is stopped) and various electric loads. Depends on the size of When the amount of charge of the battery 62 is already sufficiently large and the electric load is small, the period from time t ₀ to time t ₁ is shortened, and the maximum value P is also small. In this case, even if the command r of the target voltage given to the regulator 65 is raised from the first target value to the second target value, the power generation amount by the generator 63 does not increase so much, and fDUTY, the intake air amount and the intake pressure overshoot. The risk of doing so is small. Therefore, it is allowed to set a larger amount of increase of the target voltage per unit time to be applied to the regulator 65 after the time point t ₂ (higher increase rate).

On the contrary, when the charge amount of the battery 62 is small or the electric load is large, the period from the time point t ₀ to the time point t ₁ becomes longer and the maximum value P becomes larger. In this case, the amount of power generated by the generator 63 is significantly increased by raising the target voltage command r given to the regulator 65 from the first target value to the second target value, so that fDUTY, intake air amount, and intake air pressure are There is a high risk of overshoot. Therefore, the increase amount per unit time of the target voltage applied to the regulator 65 after the time t ₂ should be set to be smaller (the increase rate is slower).

Generally speaking, the longer the period from time t ₀ to time t ₁ and / or the larger the maximum value P, the more the voltage of the battery 62 going from the first target value to the second target value after time t ₂ . The transition of the target value rises slowly, thereby suppressing the decrease in intake negative pressure ΔP.

In any case, it is necessary to prevent fDUTY, the intake air amount, and the intake pressure from overshooting after a time point t ₂ (more than a predetermined amount or a predetermined ratio as compared with the steady value at the time point t ₃ when the time has passed). The appropriate increase rate of the target value of the battery 62 voltage after time t ₂ so as not to cause such an overshoot is experimentally obtained in advance through a conformance test, learning, etc., and stored in the memory of the ECU 0. Keep it. Then, when starting the internal combustion engine, the rising speed corresponding to the length of the period from the time point t ₀ to the time point t ₁ and the magnitude of the maximum value P is read out from the memory, and the regulator 65 is informed to the regulator 65 after the time point t _2. It is reflected in the command r of the target voltage to be applied.

  In the present embodiment, an internal combustion engine mounted on a vehicle and a generator 63 that generates electric power by receiving transmission of rotational driving force from the internal combustion engine are controlled. The voltage of the battery 62 charged by the control is controlled to the first target value, and then controlled to the second target value higher than the first target value, and the transition period from the first target value to the second target value is made. , The transition of the target value of the battery 62 voltage from the first target value to the second target value is adjusted so that the index value fDUTY of the output level of the generator 63 does not overshoot a predetermined amount or more. A control device 0 was configured.

  According to the present embodiment, it is possible to supply a large amount of negative pressure to the brake booster immediately after the start of the internal combustion engine.

Further, from the starting time point t ₀ of the internal combustion engine battery 62 voltage is in accordance with the length of the period up to time t ₁ to reach the first target value, from a first target value of the battery 62 voltage towards the second target value Since the transition of the target value is changed, when the battery 62 has already been sufficiently charged at the time of starting the internal combustion engine, the voltage of the battery 62 is quickly set to the required _second after time t2. It can be raised to the target value. On the other hand, when the charge amount of the battery 62 is small or the electric load is large at the time of starting the internal combustion engine, the voltage of the battery 62 is gradually raised to the second target value after time t ₂ to The overshoot of the power generation amount 63 can be suppressed, and the intake negative pressure ΔP to be supplied to the brake booster 5 can be secured.

The present invention is not limited to the embodiment described in detail above. For example, after the time point t ₂ when the transition from the first target value to the second target value is started, fDUTY, which is an index value indicating the output level of the generator 63, is repeatedly measured, and the fDUTY per unit time is measured. The overshoot of fDUTY, intake air amount, and intake pressure may be suppressed by adjusting the rate of increase of the target voltage applied to the regulator 65 so that the change amount (increase amount) does not exceed the required upper limit.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine and a generator mounted on a vehicle.

0 ... Control unit (ECU)
3 ... Intake passage 32 ... Throttle valve 5 ... Brake booster 62 ... Battery 63 ... Generator

Claims (2)

An internal combustion engine mounted on a vehicle and a generator that generates electric power by receiving a rotational driving force from the internal combustion engine;
In the period immediately after the start of the internal combustion engine, the voltage of the battery charged by the generator is controlled to the first target value, and then the second target value higher than the first target value is controlled.
In the transition period from the first target value to the second target value, the battery voltage target from the first target value to the second target value is set so that the index value of the output level of the generator does not overshoot more than a predetermined value. A control device that adjusts transition of values. The change of the target value of the battery voltage from the first target value to the second target value is changed according to the length of the period from the starting time of the internal combustion engine to the time when the battery voltage reaches the first target value Item 2. The control device according to Item 1.

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