JP4214812B2 - Idle stop device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is provided in a vehicle and automatically stops idling of an engine that drives the vehicle to travel through an automatic transmission when a predetermined idle stop condition such as a temporary stop waiting for a signal is established. The vehicle can be started by automatically restarting the engine by a motor fed from a battery when a predetermined restart condition based on a driver's brake release operation, a vehicle state, or the like is satisfied. The present invention relates to an idle stop device that improves fuel efficiency and reduces exhaust gas emissions while ensuring operability.
[0002]
[Prior art]
As a conventional idle stop device as described above, for example, a device that performs automatic stop and automatic restart of engine idling on condition that the automatic transmission is in the neutral range is known (for example, Patent Document 1). In this device, since the automatic transmission cannot be automatically stopped and restarted when the automatic transmission is in the drive range, the effect of improving fuel efficiency and reducing exhaust gas emissions is not sufficient. Research is underway to automatically stop and restart idling even when the automatic transmission is in the drive range.
[0003]
By the way, if the engine is restarted immediately when a predetermined restart condition is established based on the driver's brake release operation, vehicle condition, etc. after automatic idling stop (idle stop) in the drive range, Because the negative pressure in the passage is small (close to atmospheric pressure), the engine speed increases rapidly (overshoot), sudden driving force is applied to the vehicle, and unpleasant torque shock is given to the vehicle occupant. There is an inconvenience. Conventionally, in order to prevent the same inconvenience in the field of hybrid vehicles, the engine is cranked with a motor for a certain period (motor cranking) to increase the negative pressure in the engine intake passage, and then fuel injection and There is known one that suppresses overshoot and prevents occurrence of torque shock by performing ignition (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP 2001-227375 A [Patent Document 2]
Japanese Patent Laid-Open No. 2000-120455
[Problems to be solved by the invention]
However, the above-described conventional idle stop device automatically stops idling even when the automatic transmission is in the drive range, and automatically restarts after the automatic stop in the drive range. If motor cranking is always performed, the engine cooling water temperature decreases, so the engine friction torque increases, and even if the motor cranking torque increases, the motor cranking is performed. It is necessary to increase the power consumption at the time of restart and increase the battery capacity, and there is an inconvenience that the fuel efficiency improvement effect is impaired due to an increase in engine load for the charging. In order to avoid this, if the vehicle with a small battery capacity is not automatically stopped idling in the drive range when the cooling water temperature is low, there is a disadvantage that the effect of improving the fuel consumption and reducing the exhaust gas emission is not sufficient. It was.
[0006]
The inventors of the present invention who have continued research on this matter, when the engine friction torque increases because the engine cooling water temperature decreases, the negative pressure in the engine intake passage is reduced due to the increased friction torque. It has been found that even if it is not so large, the engine speed does not rise so rapidly upon restart. Therefore, in view of the above knowledge of the present inventor, the present invention performs automatic stop and automatic restart of idling even when the automatic transmission is in the drive range, and automatic restart after automatic stop in the drive range. It is an object of the present invention to provide an idle stop device that performs motor cranking prior to the above, and that reduces power consumption due to motor cranking when the engine coolant temperature is low.
[0007]
[Means for solving the problems and their functions and effects]
As shown in the conceptual diagram of FIG. 1, the idle stop device of the present invention according to claim 1 that advantageously solves the above problem is provided in a vehicle, and when the predetermined idle stop condition is satisfied, the vehicle is automatically transmitted. 1 automatically stops idling of the engine 2 that travels through the motor 1, and when a predetermined restart condition is satisfied when the automatic transmission 1 is in the drive range, the motor 4 fed from the battery 3 In the idling stop device that automatically restarts the engine 2, the cooling water temperature detecting means 5 that detects the cooling water temperature of the engine 2, and the motor speed according to the low cooling water temperature detected by the cooling water temperature detecting means 5. Motor cranking time setting means 6 for setting the ranking time short, and restarting the engine 2 when the engine 2 is automatically restarted. Prior to movement, motor drive means 7 for driving the motor 4 so that the motor 4 performs motor cranking of the engine 2 only during the motor cranking time set by the motor cranking time setting means 6; It is characterized by comprising.
[0008]
In such an idle stop device, the cooling water temperature detecting means 5 detects the cooling water temperature of the engine 2, and the motor cranking time setting means 6 corresponds to the low cooling water temperature detected by the cooling water temperature detecting means 5. Set the motor cranking time short. When the engine 2 is automatically restarted, prior to the restart of the engine 2, the motor drive means 7 is connected to the motor 2 only during the motor cranking time set by the motor cranking time setting means 6. The motor 4 is driven so as to perform motor cranking.
[0009]
Therefore, according to the idling stop device of the present invention, the lower the engine coolant temperature, the shorter the motor cranking time. Therefore, the motor torque when the engine friction torque increases because the engine coolant temperature decreases. Power consumption due to ranking can be reduced, while suppressing the overshoot with the increased friction torque and preventing the occurrence of torque shock, it is possible to prevent the decrease in fuel efficiency improvement effect due to the increase in battery capacity, In addition, even in a vehicle having a small battery capacity, idling can be automatically stopped in the drive range when the cooling water temperature is low, and a sufficient fuel consumption improvement and exhaust gas emission reduction effect can be obtained.
[0010]
In the idle stop device of the present invention, as described in claim 2, the motor cranking time setting means 6 has a cooling water temperature detected by the cooling water temperature detection means 5 equal to or lower than a predetermined temperature (for example, -20 ° C). In this case, it is preferable to set the motor cranking time to zero. Motor cranking is not required when the coolant temperature is below a predetermined temperature, at which the engine friction torque increases enough to sufficiently suppress the sudden increase in engine speed. In this case, if the motor cranking time is set to zero, This is because wasteful power consumption can be eliminated.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the idle stop device of the present invention. In FIG. 2, reference numeral 1 denotes a belt type continuously variable transmission as an automatic transmission having a torque converter 1a. Engine for driving the vehicle through the continuously variable transmission 1 and another drive system (not shown), 3 is a battery, 4 is a motor for restarting the engine 2 interposed between the engine 2 and the torque converter 1a. A motor generator (MG) is shown. Here, the motor / generator 4 has its rotor always driven and coupled to the crankshaft of the engine 2 and rotates synchronously with the crankshaft.
[0012]
The motor / generator 4 is connected to the battery 3 via the inverter 8 and normally functions as an AC generator that charges the battery 3 by driving the rotor with the crankshaft of the engine 2. When the engine is restarted, it functions as an AC motor fed from the battery 3 and rotates the crankshaft of the engine 2 with the rotor (motor cranking).
[0013]
The motor / generator 4 is switched between the AC generator function and the AC motor function, the amount of power generated when functioning as an AC generator, and the rotational speed when functioning as an AC motor are connected to the inverter 8. The fuel injection system and the ignition system of the engine 1 are connected to the fuel injection system and the ignition system, which are also connected to the normal microcomputer. The engine control module 10 is controlled by the engine control module 10. The engine control module 10 is connected to the overall control unit 9 and controlled by the overall control unit 9.
[0014]
Furthermore, a shift control module (not shown) that controls the operation of the continuously variable transmission 1, which also includes a normal microcomputer, and a battery controller 11 that checks the state of charge of the battery 3 are provided in the general control unit 9. It is connected and controlled by the integrated control unit 9. The integrated control unit 9 includes a water temperature sensor 12 as an engine water temperature detecting means 5 for detecting the cooling water temperature of the engine 2, an oil temperature sensor 13 for detecting the operating oil temperature of the continuously variable transmission 1, and a brake pedal. In addition to a brake stroke sensor 14 that detects the amount of depression of the accelerator pedal and an accelerator stroke sensor 15 that detects the amount of depression of the accelerator pedal, a hydraulic sensor (not shown) that detects the hydraulic pressure of the continuously variable transmission 1, A vehicle speed sensor (not shown) for detecting the vehicle speed of the vehicle, a negative pressure sensor (not shown) for detecting the negative pressure of the brake booster, a switch (not shown) for detecting the closed state of the door and bonnet, and the like are connected.
[0015]
In the idle stop device of the above-described embodiment mounted on such a vehicle, the continuously variable transmission 1 is in the D (drive) range and the vehicle is stopped (vehicle speed 0 km / h), and the brake pedal is depressed (ON ) And the idling of the engine 2 is automatically stopped when a predetermined idle stop condition such as the door and bonnet being closed is satisfied, thereby reducing wasteful idling fuel while the vehicle is stopped. In the idle stop state, the accelerator pedal is depressed (ON), the brake pedal is released (OFF), or the vehicle is operated in the idle stop state. Regardless of the user's operation, whether the state of charge of the battery 3 has dropped below a predetermined level, the negative pressure of the brake booster has dropped below a predetermined level, A motor start request is issued when a predetermined restart condition is established, such as when the gin water temperature falls below a predetermined level, or the hydraulic oil temperature or hydraulic pressure of the continuously variable transmission drops below a predetermined level. The engine 2 is automatically restarted (cancels the idle stop), and includes the water temperature sensor 12 as the engine water temperature detecting means 5 and according to the cooling water temperature detected by the water temperature sensor 12. Motor cranking time setting means 6 for setting the motor cranking time short, and motor cranking set by the motor cranking time setting means 6 prior to restarting the engine 2 when the engine 2 is automatically restarted. Motor driver that drives the motor / generator 4 so that the motor / generator 4 performs motor cranking of the engine 2 only for the time. 7, which comprises a, in these motor cranking time setting unit 6 and the motor driving means 7, constituted by the general control unit 9 to operate on the basis of a predetermined program specifically previously given.
[0016]
FIG. 3 is a flowchart showing a restart process after idling stop executed by the idling stop device of the above-described embodiment configured to include the water temperature sensor 12 and the comprehensive control unit 9, and here, first, in step S1, Based on signals from the shift control module, sensors, etc., the idling of the engine 2 is automatically stopped when the above-mentioned predetermined idle stop condition is satisfied when the continuously variable transmission 1 is in the D (drive) range. In the state where the continuously variable transmission 1 is in the D (drive) range, it is determined whether another predetermined restart condition is satisfied and a motor start request is issued by setting a motor start request flag or the like. If the motor start request is not issued, wait until it is issued. If it is determined that a motor start request has been issued, the cooling water temperature (engine water temperature) of the engine 2 is detected by the water temperature sensor 12 in the next step S2, and 0 ° C. shown in FIG. Between 0 and -20 ° C, the motor cranking time is shortened in proportion to the decrease in cooling water temperature, a constant 2 seconds above 0 ° C, and a constant 0 seconds below -20 ° C, or Based on the correspondence table showing the same relationship, the motor cranking time is obtained and set from the detected coolant temperature.
[0017]
Next, in step S4, the inverter 8 is started to supply power to the motor / generator 4, and the motor / generator 4 starts the motor cranking of the engine 2. In step S5, the crankshaft rotation speed ( It is determined whether or not the engine speed has reached the fuel injection target speed, and if not, wait until it reaches, and if it is determined that the engine speed has reached the fuel injection target speed, continue Whether or not the previously set motor cranking time has elapsed after the engine speed has reached the fuel injection target engine speed (idle target engine speed) from the elapsed time in step S6. If the motor cranking time has not elapsed, the crankshaft must be rotated at the target fuel injection speed. When it is determined that the motor cranking time has elapsed, in step S7, the motor / generator 4 continues to drive the crankshaft of the engine 2 and continues to drive the engine 2 to the fuel injection system and ignition system. The ignition of the plug is started, and it is determined whether or not the engine 2 has reached a complete explosion from the exhaust temperature or the like. When the engine 2 has reached a complete explosion, the motor / generator 4 causes the engine 2 to The rotation drive of the crankshaft is stopped and the complete explosion determination is finished, and the restart process is completed. Therefore, step S3 corresponds to the motor cranking time setting means 6, and steps S5 and S6 correspond to the motor driving means 7.
[0018]
According to the idle stop device of this embodiment, the water temperature sensor 12 detects the cooling water temperature of the engine 2 at step S2, and the motor cranking time according to the low cooling water temperature detected by the water temperature sensor 12 at step S3. Set to short. When the engine 2 is automatically restarted, the motor / generator 4 is connected to the engine 2 only during the motor cranking time set in steps S5 and S6 prior to the restart of the engine 2 in step S7. Since the motor / generator 4 is driven so as to perform motor cranking, the lower the coolant temperature of the engine 2 is, the shorter the motor cranking time is. The power consumption due to the motor cranking when the battery is increasing can be reduced, and the increased friction torque suppresses the overshoot and prevents the occurrence of torque shock, while the fuel consumption resulting from the increase in the capacity of the battery 3 It is possible to prevent the improvement effect from decreasing, and even in a vehicle with a small battery capacity, when the cooling water temperature is low. (Drive) to obtain performs automatic stop of idling in range, it is possible to obtain sufficiently improved fuel efficiency and exhaust gas emission reduction effect.
[0019]
Further, according to the idle stop device of this embodiment, the motor cranking is performed at a predetermined temperature at which the friction torque of the engine 2 increases enough to sufficiently suppress the rapid increase in the engine speed, for example, at an engine coolant temperature of -20 ° C or lower. In step S3, when the cooling water temperature is -20 ° C or lower, the motor cranking time is set to zero when the cooling water temperature is -20 ° C or lower. Therefore, the motor cranking is performed when the engine cooling water temperature is -20 ° C as shown in FIG. Therefore, useless power consumption can be eliminated.
[0020]
Although the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described examples. For example, the engine may be a diesel engine as well as a gasoline engine, and the automatic transmission is a stepped transmission with a torque converter. Or a stepped transmission with an electromagnetic clutch, and the restarting motor may be drivingly coupled to the crankshaft of the engine via a belt-type transmission mechanism.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of an idle stop device according to the present invention.
FIG. 2 is a block diagram showing an embodiment of the idle stop device of the present invention.
FIG. 3 is a flowchart showing processing executed by the idle stop device of the embodiment.
FIG. 4 is an explanatory diagram showing a graph used for setting the motor cranking time by the idle stop device of the embodiment.
FIG. 5 is an explanatory view showing the operation of the idle stop device of the embodiment.
[Explanation of symbols]
1 Continuously variable transmission (automatic transmission)
1a Torque converter 2 Engine 3 Battery 4 Motor / generator (motor)
5 Engine water temperature detection means 6 Motor cranking time setting means 7 Motor drive means 8 Inverter 9 General control unit 10 Engine control module 11 Battery controller 12 Water temperature sensor 13 Oil temperature sensor 14 Brake stroke sensor 15 Acceleration stroke sensor

Claims (2)

When a predetermined idle stop condition is established in a vehicle, idling of an engine that drives the vehicle to travel through the automatic transmission is automatically stopped, and the automatic transmission is in a drive range. In an idle stop device that automatically restarts the engine by a motor fed from a battery when a predetermined restart condition is established,
Cooling water temperature detecting means for detecting the cooling water temperature of the engine;
Motor cranking time setting means for setting the motor cranking time short according to the low coolant temperature detected by the cooling water temperature detection means;
When the engine is automatically restarted, the motor performs the motor cranking of the engine only during the motor cranking time set by the motor cranking time setting means prior to restarting the engine. Motor driving means for driving the motor;
An idle stop device comprising: 2. The idle stop device according to claim 1, wherein the motor cranking time setting means sets the motor cranking time to zero when the cooling water temperature detected by the cooling water temperature detecting means is not more than a predetermined temperature. .

Images