Idling stop control device

Abstract

To provide an idling-stop control device capable of suppressing vehicle body vibration when an engine is automatically restarted (recovered) from an idling stop state.SOLUTION: An ECU 20 forming an idling-stop control device 1 includes an auxiliary equipment control unit 21 for controlling the power generation amount of an alternator 25 driven by an engine 10. When the engine 10 is restarted, the auxiliary equipment control unit 21 sets a target engine rotation speed so that the time differential value of engine rotation speed becomes constant, and when an actual engine rotation speed is higher than the target engine rotation speed, the auxiliary equipment control unit increases the power generation amount of the alternator 25 so that the time differential value of the engine rotation speed becomes constant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an idling stop control device. [Background technology]

[0002] In recent years, from the viewpoint of improving fuel efficiency and reducing exhaust gas, vehicles equipped with an idling stop function (idling stop system) that automatically stops the engine when, for example, waiting for a traffic light at an intersection (when the vehicle is stopped) have been widely put into practical use. In an idling stop system, when the engine is in an idling stop state, for example, if it is detected that the brake pedal has been released, a request to restart the engine is output, and the engine is restarted (for example, see Patent Document 1).

[0003] Conventionally, when the engine is automatically restarted (recovered) from an idling stop state, the vehicle body may vibrate, causing discomfort (discomfort) to the vehicle occupants. Therefore, there has been a demand for suppression (reduction) of the vehicle body vibration when the engine is automatically restarted from an idling stop state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-329039 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an idling stop control device capable of suppressing vehicle body vibrations when the engine is automatically restarted (restored) from an idling stop state. [Means for solving the problem]

[0006] Therefore, an idling stop control device according to one embodiment of the present invention comprises an idling stop control means that automatically stops the engine and puts it into an idling stop state when specified idling stop conditions are satisfied, and automatically restarts the engine when specified restart conditions are satisfied, and an accessory control means that controls the driving state of accessories driven by the engine, and is characterized in that when the engine is automatically restarted from the idling stop state by the idling stop control means, the accessory control means controls the driving state of the accessories driven by the engine so that the time derivative of the engine rotation speed is constant. Effect of the Invention

[0007] According to the present invention, engine vibrations can be suppressed when the engine is automatically restarted (restored) from an idling stop state, and vehicle body vibrations can also be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a configuration of an idling stop control device according to an embodiment; [Diagram 2] 5 is a flowchart showing a processing procedure of engine restart processing (vibration suppression control) performed by the idling stop control device according to the embodiment. [Diagram 3] FIG. 11 is a diagram showing the relationship between the target engine rotation speed (when vibration suppression control is performed) and the conventional actual engine rotation speed (when not controlled) when the engine is restarted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] As a result of extensive research, the inventors have discovered that if the differential value of the engine rotation speed fluctuates when the engine automatically restarts from an idling stop state, the forces acting on the engine (horizontally opposed engine) in the lateral direction (y direction) and vertical direction (z direction) vary, causing the engine block to vibrate, and that this engine block vibration leads to shaking of the vehicle body, particularly in the engine rotation speed range that is the vehicle body's specific resonance point.

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals will be used for the same or corresponding parts. In each drawing, the same reference numerals will be used for the same elements, and duplicated explanations will be omitted.

[0011] First, the configuration of an idling stop control device 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of the idling stop control device 1.

[0012] The idling stop control device 1 is a device that performs an idling stop function, for example, automatically stopping the engine 10 when the vehicle is temporarily stopped at a traffic light, and automatically restarting the engine 10 when the driver releases the brake pedal when starting off. In particular, the idling stop control device 1 has a function of suppressing vehicle body vibration when the engine is automatically restarted (recovered) from an idling stop state. Details of this function will be described later.

[0013] The engine 10 is, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is an in-cylinder injection engine that directly injects fuel into the cylinders. In the engine 10, air taken in through an air cleaner is throttled by a throttle valve provided in an intake pipe, passes through an intake manifold 11, and is taken into each cylinder formed in the engine 10.

[0014] An injector 12 that injects fuel into the cylinder is attached to each cylinder of the engine 10. The injector 12 directly injects fuel pressurized by a high-pressure fuel pump into the combustion chamber of each cylinder.

[0015] In addition, a spark plug 13 for igniting the air-fuel mixture and an igniter-integrated coil 14 for applying high voltage to the spark plug 13 are attached to the cylinder head of each cylinder. In each cylinder of the engine 10, the mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 13 and combusted. Exhaust gas after combustion is discharged through an exhaust pipe 15.

[0016] A belt (not shown) for transmitting driving force is hung on a pulley attached to one end of the crankshaft 10a of the engine 10, and an alternator 25 (corresponding to a generator in the claims) is drivably connected via the belt. The driving force output from the engine 10 is transmitted to the alternator 25 via the belt, and the alternator 25 is driven.

[0017] The alternator 25 is driven by the engine 10 to generate electricity. The amount of electricity generated by the alternator 25 is controlled (adjusted) by an engine control unit (hereinafter referred to as "ECU") 20, which will be described later, according to, for example, the operating state (magnitude of electrical load) of electric components (electrical equipment). Furthermore, the amount of electricity generated by the alternator 25 is controlled so that the time derivative value of the engine rotation speed becomes constant (or approximately constant) when the engine is restarted from an idling stop state.

[0018] A cam angle sensor 16 for identifying the cylinders of the engine 10 is attached near the camshaft of the engine 10. A crank angle sensor 17 for detecting the rotational position of the crankshaft 10a is attached near the crankshaft 10a of the engine 10. A timing rotor 17a having, for example, 34 protrusions with two teeth missing, formed at 10° intervals is attached to the end of the crankshaft 10a, and the crank angle sensor 17 detects the presence or absence of the protrusions of the timing rotor 17a to detect the rotational position of the crankshaft 10a.

[0019] These sensors are connected to the ECU 20. Also connected to the ECU 20 are an accelerator opening sensor 22 that detects the depression amount (opening) of the accelerator pedal, a water temperature sensor 23 that detects the temperature (water temperature) of the cooling water, and the like. The ECU 20 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as the calculation results, a backup RAM whose stored contents are held by a battery, and an input / output I / F, etc. The ECU 20 also includes an injector driver that drives the injector 12, an output circuit that outputs an ignition signal, etc. The ECU 20 also includes a circuit that varies the amount of power generated by the alternator 25, etc.

[0020] The ECU 20 identifies the cylinder from the output of the cam angle sensor 16, and determines the engine speed from the output of the crank angle sensor 17. The ECU 20 also acquires various information such as the intake air amount, intake manifold pressure, accelerator pedal opening, air-fuel ratio of the mixture, and water temperature and oil temperature of the engine 10 based on detection signals input from various sensors. The ECU 20 then comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices based on the acquired information.

[0021] The ECU 20 is connected to a vehicle dynamic control unit (hereinafter referred to as "VDCU") 30, an idling stop control unit (hereinafter referred to as "ISCU") 40, etc. so as to be able to communicate with each other through an in-vehicle communication line 50 such as a CAN (Controller Area Network). The ECU 20 transmits acquired information such as engine rotation speed (engine rotation speed) to the ISCU 40 via the CAN 50.

[0022] The VDCU 30 is connected to a brake fluid pressure sensor 31 that detects the master cylinder pressure (brake fluid pressure (hydraulic pressure)) of a brake actuator 33, an acceleration sensor 32 that detects longitudinal and lateral acceleration, and the like. The brake fluid pressure sensor 31 detects the brake fluid pressure as an index value indicating the magnitude of the braking force (braking strength) that brakes the vehicle based on the driver's brake operation. The VDCU 30 drives the brake actuator 33 according to the amount of operation of the brake pedal to brake the vehicle, detects the vehicle behavior using various sensors (e.g., a wheel speed sensor, a steering angle sensor, an acceleration sensor, a yaw rate sensor, etc.), and suppresses skidding and ensures vehicle stability during cornering by controlling the brakes through automatic pressurization and torque control of the engine 10. The VDCU 30 transmits braking information (braking information) such as the detected master cylinder pressure (brake fluid pressure) to the ISCU 40 via the CAN 50.

[0023] In order to reduce fuel consumption and emissions, when a predetermined idling stop condition is satisfied, the ISCU 40 outputs an engine stop request signal to the ECU 20 via the CAN 50 to automatically stop the engine 10. When a predetermined idling stop cancellation condition is subsequently satisfied, the ISCU 40 outputs an engine restart request signal to the ECU 20 via the CAN 50 to restart the engine 10. Note that instead of the ISCU 40, a TCU (transmission control unit) may be configured to have the idling stop function.

[0024] More specifically, when it is determined that the brake pedal is depressed (i.e., the brake fluid pressure is greater than the restart permission brake fluid pressure (restart permission threshold value)), the vehicle speed is zero, and / or the shift position is in the D (drive) range or the N (neutral) range, the ISCU 40 transmits an engine stop request signal to the ECU 20 via the CAN 50, and stops fuel injection and ignition to the engine 10, thereby stopping the engine 10 and executing an idling stop. On the other hand, when the brake pedal is released (i.e., when the brake fluid pressure becomes equal to or lower than the restart permission brake fluid pressure) and / or when the shift position is placed in the P (parking) range or the R (reverse) range, the ISCU 40 transmits an engine restart request signal to the ECU 20 via the CAN 50, and restarts the engine 10.

[0025] Therefore, the ISCU 40 functionally comprises an idling stop control unit 41. The ISCU 40 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM whose stored contents are maintained by a battery, and an input / output I / F, etc. In the ISCU 40, the function of the idling stop control unit 41 is realized by the microprocessor executing a program stored in the EEPROM.

[0026] The idling stop control unit 41 outputs an engine restart request signal to the ECU 20 to request the restart of the engine 10 when the brake pedal begins to be released during idling stop and the brake fluid pressure falls below the restart permission brake fluid pressure.

[0027] When the ECU 20 receives an engine restart request signal from the ISCU 40, it restarts the engine 10. That is, the ECO 20 starts, for example, the starter motor 26 (corresponding to a starter in the claims) to start cranking the engine 10. Then, the ECU 20 drives the injector 12 at a predetermined fuel injection timing to inject fuel, and then restarts the engine by igniting the fuel-air mixture at a predetermined ignition timing. That is, the idling stop control unit 41 and the ECU 20 function as an idling stop control means in the claims.

[0028] In particular, the ECU 20 has a function of suppressing vibration of the vehicle body when the engine is automatically restarted from an idling stop state.

[0029] Therefore, the ECU 20 functionally includes an auxiliary control unit 21. In the ECU 20, the function of the auxiliary control unit 21 is realized by a microprocessor executing a program stored in an EEPROM or the like.

[0030] The auxiliary control unit 21 controls the driving state (power generation amount) of the alternator 25 (auxiliary) driven by the engine 10. That is, the auxiliary control unit 21 functions as an auxiliary control means described in the claims. In particular, when the engine 10 is automatically restarted from an idling stop state, the auxiliary control unit 21 controls the driving state (power generation amount) of the alternator 25 driven by the engine 10 so that the time differential value of the engine rotation speed becomes constant (i.e., so as to suppress fluctuations in the forces acting on the engine 10 in the lateral direction (y direction) and the height direction (z direction)).

[0031] Here, the force acting in the y direction is expressed by the following equation (1). Force acting in the y direction ∝ m × r z ×(dω e / dt) ···(1) Moreover, the force acting in the z direction is expressed by the following equation (2). Force acting in the z direction ∝ m × r y×(dω e / dt) ···(2) Here, m is the mass of the crankshaft 10a [kg], and r y is the crankshaft radius in the y-axis direction [m], and r z is the crankshaft radius in the z-axis direction [m], and ω e is the engine speed [rpm].

[0032] More specifically, as shown in FIG. 3, when the engine 10 is restarted (in a region where the engine speed is increasing), the auxiliary control unit 21 adjusts the target engine speed (ω e Then, when the actual engine speed (actual engine speed) is higher than the target engine speed, the auxiliary control unit 21 increases the power generation amount (i.e., the load) of the alternator 25 so that the time differential value of the engine speed becomes constant. Note that as long as the time differential value of the engine speed is constant, its magnitude (the magnitude of the gradient) does not matter. The target engine speed is set in advance so as to connect, for example, 0 rpm (during idling stop) with the idling speed after complete explosion (for example, 600 rpm).

[0033] At that time, the auxiliary control unit 21 calculates the target power generation amount of the alternator 25 based on the torque of the engine 10, the torque of the starter motor 26 that cranks the engine 10, the friction (resistance) acting on the engine 10, and the multiplication value of the inertia of the crankshaft 10a of the engine 10 and the time derivative of the target engine rotation speed.

[0034] When the engine is restarted, the following equation (3) of motion of a rotational system holds on the engine crankshaft 10a. I×(dω e / dt)=T engine +T starter -T friction +T alternater (3) I is the engine crankshaft inertia [kg*m^2] T engineis the engine torque [Nm] T starter is the starter torque [Nm] T friction is the friction torque [Nm] T alternater is the alternator generating torque [Nm]

[0035] Therefore, in the region where the actual engine speed exceeds the target engine speed, the differential value of the engine speed (dω e The alternator 25 generates electricity so that the current (T alternater (generating a torque <0[Nm]) reduces engine speed overshoot (i.e., force fluctuations).

[0036] More specifically, the auxiliary control unit 21 determines the power generation torque T to be instructed to the alternator 25 based on the following equation (4): alternater Obtain instructions (target power generation torque = target power generation amount). T alternater instruction=min(-T engine -T starter +T friction +I×(dω e Target / dt),0[Nm])...(4)

[0037] That is, the auxiliary control unit 21 engine -T starter +T friction +I×(dω e The smaller of the target / dt) and 0 is T alternater Then, the auxiliary control unit 21 sets the target power generation torque to the target power generation amount. alternater A field current command (= target power generation amount) corresponding to the command is sent to the alternator 25.

[0038] At that time, the auxiliary control unit 21 engine (The torque of the engine 10) is obtained based on, for example, the intake air amount (g / s) of the engine 10, or the throttle valve opening degree and the engine rotation speed.

[0039] In addition, the auxiliary control unit 21starter The torque of the starter motor 26 is calculated based on the engine speed. For example, the EEPROM of the ECU 20 stores the engine speed and T starter A map (starter torque map) that defines the relationship between the torque of the starter motor 26 and the engine speed is stored, and the starter torque map is searched based on the engine speed to obtain T starter In the starter torque map, the map value (torque of the starter motor 26) is set to 0 [Nm] at a predetermined engine rotation speed or higher (region after the initial explosion).

[0040] Similarly, the auxiliary control unit 21 friction (friction acting on the engine 10) is calculated based on, for example, the engine rotation speed and the water temperature or oil temperature. For example, the EEPROM of the ECU 20 stores the engine rotation speed, the water temperature or oil temperature, and T friction A map (friction map) that defines the relationship between the engine speed and the water or oil temperature is stored, and the T friction (friction acting on the engine 10) is required. friction The friction acting on the engine 10 may be calculated based only on the engine rotation speed. Examples of the friction acting on the engine 10 include friction (resistance) of the transmission, compressor, and the like.

[0041] As a result, overshooting of the engine rotation speed is suppressed, and vibration of the engine 10 is suppressed (reduced). However, since the alternator 25 cannot generate torque on the drive side (torque greater than 0), it cannot control the actual engine rotation speed to increase in a region where the actual engine rotation speed is lower than the target engine rotation speed.

[0042] Then, when the engine rotation speed becomes equal to or greater than a predetermined rotation speed (e.g., 600 rpm) (i.e., when it is determined that the engine 10 has completely exploded), the auxiliary control unit 21 terminates controlling the driving state (power generation amount) of the alternator 25 (vibration suppression control) so that the time derivative of the engine rotation speed becomes constant, as described above.

[0043] Next, the operation of the idling stop control device 1 will be described with reference to Fig. 2. Fig. 2 is a flowchart showing the procedure of engine restart processing (vibration suppression control) by the idling stop control device 1. This processing is mainly executed by the ECU 20 and is repeatedly executed at predetermined time intervals.

[0044] In step S100, during idling stop (engine automatic stop), it is determined whether or not an engine restart request for restarting the engine 10 has been received (i.e., whether or not the restart conditions from the idling stop state have been satisfied). If an engine restart request for restarting the engine 10 has not been received, the process is temporarily terminated and the idling stop state continues. On the other hand, when an engine restart request for restarting the engine 10 has been received, the process proceeds to step S102.

[0045] In step S102, the restart of the engine 10 is started. That is, the starter motor 26 is started to start cranking of the engine 10. Then, the injector 12 is driven at a predetermined fuel injection timing to inject fuel, and thereafter, the fuel-air mixture is ignited at a predetermined ignition timing to start the restart of the engine 10.

[0046] Next, in step S104, the target engine speed is set so that the time differential value of the engine speed is constant. Note that the method for setting the target engine speed is as described above, and therefore a detailed description thereof will be omitted here.

[0047] Next, in step S106, it is determined whether the actual engine speed is higher than the target engine speed. If the actual engine speed is equal to or lower than the target engine speed, the process proceeds to step S110. On the other hand, if the actual engine speed is higher than the target engine speed, the process proceeds to step S108.

[0048] In step S108, a target power generation amount of the alternator 25 is calculated, and the driving state of the alternator 25 is controlled so that the power generation amount of the alternator 25 coincides with the target power generation amount. That is, the driving state (power generation amount) of the alternator 25 is controlled so that the time differential value of the engine rotation speed becomes constant. Note that the method of calculating the target power generation amount of the alternator 25 is as described above, and therefore a detailed description thereof will be omitted here.

[0049] In step S110, it is determined whether the engine rotation speed is equal to or higher than a predetermined rotation speed (for example, 600 rpm). If the engine rotation speed is less than the predetermined rotation speed, the process proceeds to step S104, and the above-mentioned steps S104 to S110 are repeatedly executed until the engine rotation speed becomes equal to or higher than the predetermined rotation speed. On the other hand, when the engine rotation speed becomes equal to or higher than the predetermined rotation speed (i.e., when it is determined that the engine has completely exploded), this process is terminated and exited from this process.

[0050] As described above, according to this embodiment, when the engine 10 is automatically restarted from an idling stop state, the target engine speed is set so that the time differential of the engine speed is constant, and when the actual engine speed is higher than the target engine speed, the amount of power generated by the alternator 25 driven by the engine 10 is increased so that the time differential of the engine speed is constant. That is, the amount of power generated by the alternator 25 is increased (the load is increased) to adjust the time differential of the engine speed to be constant. As a result, engine vibrations can be suppressed when the engine is automatically restarted from an idling stop state, and vehicle body vibrations can be suppressed.

[0051] According to this embodiment, the target power generation amount of the alternator 25 is calculated based on the torque of the engine 10, the torque of the starter motor 26 that cranks the engine 10, the friction (resistance) acting on the engine 10, and the multiplication value of the inertia of the crankshaft 10a of the engine 10 and the time derivative of the target engine rotation speed. Therefore, the target power generation amount of the alternator 25 can be accurately determined so that the time derivative of the engine rotation speed is constant.

[0052] According to this embodiment, the torque of the starter motor 26 is found based on the engine rotation speed, so that the torque of the starter motor 26 can be found (estimated) with high accuracy.

[0053] Similarly, according to this embodiment, the friction acting on the engine 10 is found based on the engine speed and the water temperature or oil temperature, so that the friction acting on the engine can be found (estimated) with high accuracy.

[0054] According to this embodiment, when the engine rotation speed becomes equal to or higher than a predetermined rotation speed (i.e., when it is determined that the engine 10 has completely exploded), control of the driving state (power generation amount) of the alternator 25 so that the time derivative of the engine rotation speed becomes constant (vibration suppression control) is terminated, so that the above control (vibration suppression control) can be terminated at an appropriate timing.

[0055] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the present invention is applied to a gasoline engine vehicle, but the present invention can also be applied to a vehicle having a driving force source other than a gasoline engine, such as a hybrid vehicle (HEV) using an engine and a motor generator (MG) as a driving force source. In this case, the motor generator (MG) functions as a generator as recited in the claims. Also, another motor generator (MG) functions as a starter as recited in the claims.

[0056] In the above embodiment, the driving state (power generation amount) of the alternator 25 driven by the engine 10 is controlled in order to keep the time derivative value of the engine rotation speed constant. However, instead of the alternator 25, the driving state (load state) of another accessory driven by the engine 10 may be controlled.

[0057] The system configuration of the above embodiment is merely an example, and the system configuration of the present invention is not limited to the above embodiment. For example, the ECU 20 and the ISCU 40 may be integrated into one unit. Also, instead of the ISCU 40, a TCU (transmission control unit) may be provided with an idling stop function. [Explanation of symbols]

[0058] 1. Idling stop control device 10 Engine 17 Crank angle sensor 20 Engine Control Unit (ECU) 21 Auxiliary control unit 22 Accelerator opening sensor 23 Water temperature sensor 25 Alternator (generator / auxiliary) 26 Starter motor (starter) 30 Vehicle Dynamic Control Unit (VDCU) 31 Brake fluid pressure sensor 40 Idling Stop Control Unit (ISCU) 41 Idling stop control unit 50 CAN

Claims

1. an idling stop control means for automatically stopping the engine to bring it into an idling stop state when a predetermined idling stop condition is satisfied, and automatically restarting the engine when a predetermined restart condition is satisfied; an auxiliary control means for controlling a drive state of an auxiliary driven by the engine, the auxiliary control means controls a drive state of an auxiliary driven by the engine so that a time differential value of an engine rotation speed becomes constant when the engine is automatically restarted from an idling stop state by the idling stop control means; The auxiliary machine is a generator, The auxiliary control means sets a target engine rotation speed so that a time derivative of the engine rotation speed becomes constant when the engine is restarted, and, when an actual engine rotation speed is higher than the target engine rotation speed, increases the amount of power generated by the generator so that the time derivative of the engine rotation speed becomes constant.

2. 2. The idling stop control device according to claim 1, wherein the auxiliary control means calculates the target power generation amount of the generator based on the torque of the engine, the torque of a starter that cranks the engine, friction acting on the engine, and a multiplication value of the inertia of the crankshaft of the engine and a time derivative value of the target engine rotation speed.

3. 3. The idling stop control device according to claim 2, wherein the auxiliary control means determines the torque of the starter based on an engine rotation speed.

4. 4. The idling stop control device according to claim 2, wherein the auxiliary control means determines the friction acting on the engine based on the engine rotation speed.

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