JP2005291158A - Power generation control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power generation control device which achieves both securing of a battery charging capacity and reduction in the output of an engine used to drive a power generator. <P>SOLUTION: In an idling-stop vehicle which performs automatic stop/restart of an engine 1 according to operational conditions; the power generation control device of an internal combustion engine comprises a power generator 2 which supplies power which is generated by the power generator driven by the engine 1 to a battery 3 and an in-vehicle electric equipment; power generation voltage controlling means 4 which controls the power generation voltage of the power generator 2; a voltage detecting means 5 which detects the power generation voltage of the power generator 2; a running conditions detecting means 5 which detects the running conditions of a vehicle; and a power generation voltage reducing means 4 which causes the power generation voltage of the power generator to be lower than under running conditions wherein the frequency of idling-stop operation is high, when it is determined from a value detected by the running conditions detecting means that the vehicle is operated under running conditions wherein the frequency of idling-stop operation is low. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to vehicle power generation amount control, and more particularly to vehicle power generation amount control having an idle stop function.

  Electric power consumed by electrical components mounted on the vehicle is supplied by a generator driven by engine output and a chargeable / dischargeable battery. The amount of charge of the battery is charged by the operation control of the generator. The battery is controlled to be discharged when the power consumption exceeds the power generated by the generator, and charged in the opposite case.

  In an idle stop vehicle that stops the engine when a predetermined condition is satisfied while the vehicle is stopped, etc., in order to secure the electric power necessary for restarting the engine after releasing the idle stop, the battery charge amount is increased, that is, the power generation amount is reduced. It is desirable to control to increase.

  However, in order to improve acceleration performance and fuel consumption, it is desirable to minimize the amount of power generation to reduce engine output loss due to driving the generator.

  As described above, securing power for restart and reducing engine load are conflicting requirements.

Patent Document 1 provides a means for detecting power consumption in a vehicle having a function (idle stop function) for automatically stopping and restarting an engine when a predetermined condition is satisfied while the vehicle is stopped. However, when power consumption is low, a system for stopping power generation by a generator is disclosed.
JP 2001-173481 A

  However, in the system described in Patent Document 1, the operation of the generator is controlled to be kept to the minimum necessary, and it is necessary for restart when the battery charge amount is reduced by using an air conditioner or the like during idle stop. In order to secure sufficient electric power, it is necessary to start the engine and generate electric power. In addition, even when the vehicle is stopped, a situation where idle stop cannot be performed due to insufficient battery charge may occur.

  That is, in the system described in the cited document 1, it is impossible to achieve both securing of restarting power and reduction of engine load.

  In view of the above, an object of the present invention is to provide a system that ensures power for restarting to reliably perform idling stop and that reduces the load on the engine during traveling to improve fuel efficiency and output.

  The power generation control device according to the present invention generates power by being driven by the engine in an idle stop vehicle that automatically stops and restarts the engine according to operating conditions, and supplies the generated power to the battery and the on-vehicle electric device. A generator, a power generation voltage control means for controlling the power generation voltage of the generator, a voltage detection means for detecting the power generation voltage of the generator, a travel state detection means for detecting the travel state of the vehicle, and the travel state detection When it is determined from the detected value of the means that it is a traveling state where the frequency of performing idle stop is low, the generated voltage of the generator is reduced to be lower than the traveling state where the frequency of performing idle stop is high, and With

  According to the present invention, when the frequency of idling stop is high, the power generation voltage is set to a high value to reliably charge the battery, ensuring power for restart from idling stop, and performing idling stop. When the possibility is low, the generated voltage is lowered to reduce the load on the engine, so that it is possible to achieve both the securing of electric power for restart from the idle stop and the reduction of the engine load during traveling.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an engine start / stop system for an idle stop vehicle to which the present embodiment is applied.

  DESCRIPTION OF SYMBOLS 1 is an engine, 2 is a generator which is driven by the rotation of the crankshaft of the engine 1 to generate electric power, 3 is a battery which is a drive source of in-vehicle electrical components, 5 is a throttle opening sensor, an accelerator opening sensor, a vehicle speed sensor, A module (hereinafter referred to as an engine control module (ECM)) for detecting the running state of the vehicle including a sensor for detecting the voltage of the generator, etc. 4 is a total control for performing various control of the vehicle based on signals from the ECM 5 Unit (TCU).

  The generator 2 is driven by the output of the engine 1 transmitted by a belt 14 wound around a crank pulley 7 provided at the end of the crankshaft 12 of the engine 1 and a pulley 8 provided on the rotary shaft 13 of the generator 2. Is done. Further, a drive plate 9 having a ring gear 10 provided on the outer peripheral portion is connected to an end of the crankshaft 12 opposite to the crank pulley 7. When the engine 1 is started, the pinion gear 11 provided on the shaft of the starter motor 6 enters the ring gear 10 to forcibly crank the engine 1.

  The battery 3 is controlled by the TCU 4 to be discharged when the power consumption of the vehicle exceeds the power generated by the generator 2 and to be charged in the opposite case.

  In the vehicle of the present embodiment configured as described above, for example, the vehicle speed is zero km / h while the transmission is in the travel range, and the charge amount of the battery 3 (hereinafter referred to as the battery SOC) restarts the engine 1. A so-called idle stop device is provided that stops the engine 1 when a condition such as sufficient is satisfied, and automatically restarts the engine 1 when the driver depresses the accelerator.

  If the car navigation system, audio, air conditioner, or the like is operated even during idling stop, the battery SOC becomes low. Therefore, for example, in a situation where idle stop is frequently performed such as a traffic jam road, the power generation voltage of the generator 2 is controlled to be increased to, for example, 14.4 V during traveling after the idle stop is released. Such control for setting the power generation voltage of the generator 2 during traveling to a higher value is power generation voltage variable prohibition control (IS control) as the first power generation mode.

  However, in the IS control, the output of the engine 1 used for driving the generator 2 is increased, and the fuel consumption is deteriorated. Therefore, in order to improve fuel consumption, for example, the power generation voltage is decreased during acceleration to reduce the load on the engine 1, and the power generation voltage is increased during deceleration fuel cut to perform intensive charging. The generated voltage is variably controlled in accordance with the operating conditions. This control is power generation voltage variable allowable control (ALT power generation voltage control) as the second power generation mode.

  The TCU 4 switches between the IS control and the ALT power generation voltage control according to the traveling state of the vehicle, and performs control so as to achieve both securing of electric power and reduction of engine output used for power generation.

  Next, switching between IS control and ALT power generation voltage control will be described with reference to FIG. 2, FIG. 3, and FIG.

  FIG. 2 is a flowchart of switching control between IS control and ALT power generation voltage control performed by the TCU 4.

  FIG. 3 is a table showing the driving situation assumed in the present embodiment, its detection means, conditions, and the power generation state of the generator in each driving situation.

  There are four possible driving situations: a congested road, a suburban road, a highway, and others. Others are situations where IS control is prohibited depending on the driver's intention, driving condition, external environment, and the like. For example, the driver has set the idle stop prohibition switch to ON, the air conditioner is operating at the maximum air volume, the engine 1 is heavily loaded to rotate the compressor, and the transmission shift pattern is set to a sports mode that emphasizes acceleration. High engine output is required, the outside air temperature is extremely high or extremely low, the load on the air conditioner is large, the ABS is operating and the load for driving the pump for the ABS unit is large, etc. .

  Congested roads, suburban roads, and highway roads are determined as follows based on the elapsed time after idling stop, vehicle speed, and battery SOC.

  On a congested road, the elapsed time from idle stop is 0 to 5 minutes, the vehicle speed is 0 to 20 km / h, and the battery SOC is 85% or less.

  For suburban roads, the elapsed time from idle stop is 5 to 10 minutes, the vehicle speed is 20 to 70 km / h, and the battery SOC is 85 to 95%.

  The highway satisfies the conditions that the elapsed time from idle stop is 10 minutes or more, the vehicle speed is 70 km / h or more, and the battery SOC is 95% or more. Note that it is possible to determine whether or not the vehicle is currently traveling on a highway by the ETC system.

  The power generation state of the generator in each of the above traveling situations is IS control on a congested road, and ALT power generation voltage control on a highway and others. On suburban roads, either IS control or ALT control is performed depending on the previous driving situation or the predicted driving situation. For example, ALT control is used when driving on suburban roads where there is no traffic congestion after high speed driving, and IS control is performed when it is found from the information of the car navigation system that the driving route ahead is congested.

  FIG. 4 is a table showing an example of conditions for switching between IS control and ALT power generation voltage control.

  4 is a condition for shifting from IS control to ALT power generation voltage control, and condition 2 is a condition for shifting from ALT power generation voltage control to IS control.

  Specifically, condition 1 is: a: 10 minutes or more have passed since the engine start after idling stop, b: traveling at a vehicle speed of 20 km / h or more continues for 5 minutes or more, c: a vehicle speed of 70 km / h or more Corresponds to at least one of the items that the vehicle travels for 1 minute or longer, and e: the operating condition that the battery SOC is 95% or higher, or the battery SOC is 95% or higher, and f : It corresponds to either one of the driving | running conditions that other IS control prohibition conditions are satisfied. Note that the case where f: other IS control prohibition conditions are satisfied is, for example, the case where the air conditioner is operating at the maximum air volume, or the case where a shift pattern emphasizing acceleration is selected.

  Condition 2 corresponds to one of the following conditions: g: idle stop has started, h: vehicle speed is zero km / h, i: battery SOC is 85% or less. In other words, if the battery SOC is 85% or more, the ALT power generation voltage control is not switched to the IS control unless the vehicle stops even on a congested road.

  Hereinafter, description will be given according to each step of FIG.

  In step S1, it is determined whether condition 2 is satisfied. If established, the process proceeds to step S4 described later. If not, the process proceeds to step S2.

  In step S2, it is determined whether Condition 1 is satisfied. If not, the process proceeds to step S3. If established, the process proceeds to step S6.

  In step S3, it is determined whether or not the flag (ALT FLAG) is zero. ALT FLAG is set to zero when the IS control is executed, and is set to 1 when the ALT power generation voltage control is executed.

  If ALT FLAG is zero in step S3, the process proceeds to step S6, and if not, the process proceeds to step S4.

  In step S4, ALT power generation voltage control is executed, and ALT FLAG is set to 1 in step S5.

  In step S6, IS control is executed, and in step S7, ALT FLAG is set to zero.

  As described above, the TCU 4 sets conditions for executing switching from IS control to ALT power generation voltage control and vice versa, and performs switching according to the established condition. If none of the conditions is satisfied, the current control is continued.

  Next, with respect to changes in the vehicle speed, the battery SOC, the accelerator opening, and the ALT power generation voltage (= battery voltage) when switching is performed according to the flowchart of FIG. This will be described with reference to the chart.

  The time when the vehicle speed is reduced to zero km / h and the idle stop is started is set to t0. At this time, switching to IS control is performed.

  From t0 to t1, the accelerator opening is zero%. Since the engine 1 is stopped, the power generation voltage of the generator 2 is also zero V. Therefore, the battery SOC decreases.

  When the accelerator pedal is depressed at t1, the engine 1 automatically restarts and the generator 2 starts generating power, so the battery SOC rises. Since the IS control is in progress, the generated voltage is controlled to be 14.4V. In addition, when the vehicle speed exceeds 20 km / h after resuming traveling, a timer is activated to count the traveling time at 20 km / h or more. When the traveling time becomes 5 minutes or more, the ALT power generation voltage control is switched. Here, the vehicle speed becomes zero km / h at t2 within 5 minutes, and the same change from t0 to t1 is repeated.

  At t3, the accelerator pedal is depressed again, the engine 1 is restarted, and the generator 2 starts generating power at the generated voltage of 14.4V. When the vehicle speed exceeds 20 km / h at t4, the timer starts counting. The battery SOC rises because it is charged by the generator 2.

  At t5, the vehicle travels at a speed of 20 km / h or more for 5 minutes or more and satisfies the condition 1 that the battery SOC is 95% or more. Therefore, the power generation voltage is switched to ALT power generation voltage control to reduce engine output loss. Is reduced to 13V.

  After switching to the ALT power generation voltage control at t5, the vehicle keeps running with the accelerator on until t6, and at t6, the accelerator is turned off to start deceleration. During deceleration with the accelerator off, fuel injection into the engine 1 is stopped, so that a so-called deceleration fuel cut state is established. At this time, the generator 2 is controlled so that the generated voltage is increased to 14V. Thereby, since the load for rotating the generator 2 increases and the load to the engine 1 increases, the effect of an engine brake improves.

  T7 to t8 travel with a small accelerator opening, and t8 to t9 travel with a large accelerator opening. During this time, the generated voltage remains at 13V, so even when the accelerator opening is increased at t8, the load on the engine 1 is small and the engine output used for power generation is small, resulting in a reduction in acceleration performance. Can be prevented.

  Since the accelerator is turned off at t9 and deceleration is started, the power generation voltage rises to 14V as in t6 to t7.

  When the vehicle speed becomes zero km / h at t10, the battery SOC is 95% or more, so the idle stop is started and the process proceeds to IS control. After t10, the same repetition as t0 to t10 is repeated.

  The battery SOC may be less than 85% when the idle stop state continues, but is 85% or more in other cases.

  As described above, in the present embodiment, depending on the traveling state of the vehicle, for example, on a congested road where the vehicle frequently stops, the power generation voltage during driving is increased, and on a suburban road or a highway where the number of stops of the vehicle is low By controlling the generator's power generation voltage so that the battery is intensively charged by reducing the power generation voltage of the vehicle and increasing the power generation voltage at the time of deceleration fuel cut, the idle stop is surely ensured when the vehicle is stopped The engine output used for driving the generator during driving can be reduced, so that in addition to the fuel efficiency improvement effect due to idling stop, the fuel efficiency and driving performance improvement due to power generation voltage control can also be obtained .

  Specifically, fuel consumption can be improved by about 10% by idling stop and by about 1% by power generation voltage control.

  A second embodiment will be described.

  In this embodiment, the system configuration and control flow are basically the same as those in the first embodiment, but the method for determining the driving situation is different.

  In the first embodiment, the vehicle speed is used as one of the determination conditions of the traveling situation, but in this embodiment, information from the car navigation system is used instead of the vehicle speed. Specifically, it is determined from the car navigation system information whether the road condition ahead is a congested road, a suburban road, or a highway.

  Therefore, the switching condition 1 from the IS control to the ALT power generation voltage control is also replaced with the condition that b: traveling at a vehicle speed of 20 km / h or more is continued for 5 minutes, and c: traveling at a vehicle speed of 70 km / h or more is continued for 1 minute. : Use the condition that it is found from the car navigation system information that the road ahead is not congested. As a result, it is not necessary to detect the vehicle speed for a predetermined time, and switching can be performed as soon as the road condition is found from the car navigation system information.

  As described above, the present embodiment can achieve the same effects as those of the first embodiment, and moreover, the power generation control can be switched more quickly than the determination based on the vehicle speed.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

  The present invention can be applied to a vehicle that performs idle stop.

It is a figure showing the structure of the system of this embodiment. It is a control flowchart of this embodiment. It is a figure showing the control state of the generator according to a driving | running | working condition. It is a figure showing the switching conditions of electric power generation control. It is a timing chart at the time of performing control of this embodiment.

Explanation of symbols

1 Engine 2 Generator 3 Battery 4 Total Control Unit (TCU)
5 Engine control module (ECM)
6 Engine starting motor 9 Drive plate 10 Ring gear 11 Pinion gear

Claims (8)

In an idle stop vehicle that automatically stops and restarts the engine according to the driving conditions,
A generator that generates electric power by being driven by the engine, and supplies the generated electric power to a battery and an in-vehicle electric device;
Power generation voltage control means for controlling the power generation voltage of the generator;
Voltage detection means for detecting the power generation voltage of the generator;
Traveling state detecting means for detecting the traveling state of the vehicle;
When it is determined from the detection value of the running state detection means that the running state is low in idling stop, the generated voltage of the generator is lower than the running state in which idling stop is high. A power generation control device for an internal combustion engine.   2. The power generation of the internal combustion engine according to claim 1, wherein when the battery charge amount detected by the running state detection means is equal to or greater than a predetermined value, the power generation voltage of the generator is reduced regardless of the frequency of idling stop. Control device.   The power generation control device for an internal combustion engine according to claim 2, wherein the predetermined value of the battery charge amount is about 85%.   2. The internal combustion engine according to claim 1, wherein the determination of the frequency of performing the idle stop is performed based on information of the car navigation system, and it is determined that the frequency of performing the idle stop is low when the travel route ahead is not congested. Power generation control device.   The determination of the frequency of performing the idle stop is performed based on the vehicle speed detected by the traveling state detecting means, and it is determined that the frequency of performing the idle stop is low when traveling at a predetermined vehicle speed continues for a predetermined time. The power generation control device for an internal combustion engine according to claim 1.   5. The internal combustion engine according to claim 4, wherein the predetermined speed and the predetermined period of time are either one in which traveling at 20 km / h or more continues for approximately 5 minutes or traveling at 70 km / h or more continues for approximately one minute. Power generation control device.   The determination of the frequency of performing the idle stop is performed based on the shift pattern of the automatic transmission detected by the running state detecting means, and the frequency of performing the idle stop is low when a shift pattern emphasizing acceleration is selected. The power generation control device for an internal combustion engine according to claim 1, wherein   2. The internal combustion engine according to claim 1, wherein the determination of the frequency of performing the idle stop is performed based on information of a car navigation system, and when it is determined that the vehicle is traveling on an expressway, the frequency of performing the idle stop is determined to be low. Engine power generation control device.

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