JP2004278365A - Engine stopping-starting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine stopping-starting system for quickly and smoothly starting an engine by preventing starting failure caused by reduction in fuel pressure when stopping the engine while restraining electric power consumption by driving of a fuel pump when stopping the engine. <P>SOLUTION: The engine is stopped when a prescribed stopping condition is realized (Step S2, and 4). The fuel pressure Pf is maintained in a prescribed value PO or more by driving the fuel pump every time when the fuel pressure Pf of a fuel line detected by a fuel pressure sensor becomes less than the prescribed pressure PO (Step S8, and 14) when stopping the engine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine stop / start device that automatically stops and starts an engine.
[0002]
[Related background art]
Engine stop and start devices are implemented in various fields, for example, idle stop for temporarily stopping the engine temporarily for the purpose of saving fuel consumption and reducing emissions while the vehicle is stopped due to signal waiting or traffic congestion. Applied to vehicles. In this type of idle stop vehicle, engine stop conditions such as a vehicle speed of 0 km / h, clutch engagement, and a neutral shift position are satisfied, and the engine is stopped when the vehicle is assumed to be stopped, and then the clutch is disconnected. When the engine start condition indicating the driver's intention to start is satisfied, the engine is started by the starter to prepare for start.
[0003]
In the idle stop vehicle, the fuel pump is also stopped in synchronization with the stop of the engine, thereby suppressing a decrease in the charge level (SOC: State Of Charge) of the battery during stop of the engine, in which the alternator cannot generate power. For example, see Patent Document 1).
The technology described in Patent Document 1 drives a fuel pump prior to starting an engine by a starter based on a clutch depression amount when an engine starting condition by clutch disengagement is established. Although the generated vapor is eliminated to improve the restartability, there is no difference in stopping and holding the fuel pump while the engine is stopped as described above.
[0004]
[Patent Document 1]
Patent No. 3099385 [0005]
[Problems to be solved by the invention]
The engine stop time during the idle stop varies in accordance with, for example, a signal switching state or a traffic congestion state. On the other hand, when the power supply to the fuel pump is stopped while the engine is stopped, the fuel pressure gradually decreases. Therefore, if the engine stop state is continued for a long time, the fuel pressure at the time of restart greatly decreases from the specified value, and the fuel pressure recovers at the time of engine cranking even if voltage is applied to the fuel pump. Until the ignition, the state in which ignition is impossible due to lean fuel continues, and there is a possibility that quick and smooth engine start becomes difficult.
[0006]
In an idle stop vehicle that requires the vehicle to start immediately after the engine is started, a quicker engine start is required as compared to a normal start by the driver, and a delay in the engine start gives the driver an uneasy feeling, and consequently the idle It was also a factor that impaired the commerciality as a stop vehicle.
An object of the present invention is to suppress a power consumption by driving a fuel pump while an engine is stopped, and to prevent a start failure caused by a decrease in fuel pressure while the engine is stopped, thereby realizing a quick and smooth engine start. It is an object of the present invention to provide a device for starting and stopping the engine.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a fuel pump for supplying fuel to an engine, an engine that stops when a predetermined stop condition is satisfied, and an engine that stops when a predetermined start condition is satisfied. Engine stop / start means for starting, fuel pump stop means for stopping the fuel pump when the engine is stopped by the engine stop / start means, and pressure of fuel supplied to the engine while the fuel pump is stopped by the fuel pump stop means And a fuel pressure maintaining means.
[0008]
Therefore, the fuel is supplied by the fuel pump, the engine is operated, and when a predetermined stop condition is satisfied, the engine is stopped by the engine stop and start means, and the fuel pump is stopped by the fuel pump stop means. When the condition is satisfied, the engine is restarted by the engine stop / start means.
Since the fuel pump is stopped while the engine is stopped, energy for driving the fuel pump is not consumed, fuel efficiency can be improved, and the fuel pressure is maintained by the fuel pressure maintaining means while the fuel pump is stopped. Is maintained, the engine is started under an appropriate fuel pressure, and the engine is started quickly and smoothly without causing a start failure.
[0009]
According to a second aspect of the present invention, in the first aspect, the fuel pressure maintaining means drives the fuel pump every predetermined time.
Therefore, the fuel pressure is maintained by driving the fuel pump every predetermined time, the engine is started under an appropriate fuel pressure, and the fuel pump is intermittently driven based on the predetermined time. Therefore, energy consumption for driving the pump is reduced as compared with the case where driving of the fuel pump is continued. In addition, since the fuel pump is only driven at predetermined time intervals, sensors for pump control are not required.
[0010]
According to a third aspect of the present invention, in the first aspect, the fuel pressure maintaining means includes a fuel pressure detecting means for detecting a pressure of the fuel supplied to the engine, and the fuel pressure detected by the fuel pressure detecting means falls below a predetermined value. Sometimes the fuel pump is driven.
Therefore, the fuel pump is driven each time the fuel pressure detected by the fuel pressure detecting means falls below a predetermined value, whereby the fuel pressure is maintained, and the engine is started under an appropriate fuel pressure, and Since the fuel pump is intermittently driven based on the predetermined value, energy consumption for driving the pump is reduced as compared with the case where the fuel pump is continuously driven. Moreover, since the fuel pump is controlled based on the actual fuel pressure, the fuel pressure is reliably maintained at or above a predetermined value set as an appropriate value, and high reliability is realized.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in an engine stop / start device for an idle stop vehicle will be described.
1, the engine 1 is configured as an in-line four-cylinder gasoline engine of an intake pipe injection type. A fuel injection valve 3 is provided for each cylinder in an intake passage 2 of the engine 1, and each fuel injection valve 3 is connected via a fuel line 4 to a fuel tank 5 mounted at the rear of the vehicle. During operation of the engine 1, gasoline in a fuel tank 5 is pumped up by an electric fuel pump 6, adjusted to a specified pressure by a regulator (not shown), and supplied to a fuel injection valve 3 via a fuel line 4.
[0012]
The intake air introduced into the intake passage 2 from an air cleaner (not shown) is mixed with the fuel injected from the fuel injection valve 3 after the flow rate is adjusted by the throttle valve 7, and is mixed as an air-fuel mixture with the opening of the intake valve. 8 is introduced. Thereafter, the air-fuel mixture is ignited by the ignition plug 9 at a predetermined timing, and the exhaust gas after combustion is discharged from the combustion chamber 8 into the exhaust passage 10 and discharged to the outside through a catalyst and a muffler (not shown).
[0013]
A starter generator 11 is provided on one side of the engine 1, and a pulley 12 of the starter generator 11 is connected to a crank pulley 15 of the engine 1 by a belt 16 together with a water pump pulley 13 and an idler pulley 14. The starter generator 11 functions not only as an alternator for power generation but also as a starter motor for starting the engine.
[0014]
That is, during operation of the engine, the crank pulley 15 is driven to rotate together with the water pump pulley 13 via the belt 16 to generate electric power for charging the vehicle-mounted battery and for power consumption by the electric load. Conversely, the crank 1 is driven via the belt 16 to crank the engine 1. The starter generator 11 is used not only at the time of starting the engine at idle stop, which will be described later, but also at the time of normal starting cranking based on the driver's key operation.
[0015]
Although not shown, the engine 1 configured as described above is connected to an automatic transmission and mounted on a vehicle, and a driver operates the vehicle by performing a shift operation to a driving range such as a D range. I have.
On the other hand, an ECU 21 provided with an input / output device (not shown), storage devices (ROM, RAM, BURAM, etc.) for storing control programs, control maps, and the like, a central processing unit (CPU), a timer counter, etc. (Engine control unit) is installed. On the input side of the ECU 21, a vehicle speed sensor 22 for detecting a vehicle speed V, a brake switch 23 for detecting a brake operation state by a driver, an accelerator sensor 24 for detecting an accelerator operation amount Acc, and a shift for detecting a shift position of an automatic transmission. A position sensor 25, a fuel pressure sensor 26 (fuel pressure detecting means) provided on the fuel line 4 upstream of the fuel pump 6 and detecting the pressure (fuel pressure) Pf of the fuel supplied to the fuel injection valve 3; Various switches and sensors are connected. The output side of the ECU 21 is connected to the fuel injection valve 3, the fuel pump 6, the spark plug 9, the starter generator 11, and other devices.
[0016]
The ECU 21 executes various controls for operating the engine 1 such as fuel injection control and ignition timing control based on the above-described respective detection information. In addition, while the vehicle is stopped due to a signal waiting or traffic congestion, idle stop control for temporarily automatically stopping the engine 1 is executed to reduce fuel consumption and emission, and to reduce the fuel consumption while the engine is stopped. The operating state of the fuel pump 6 is controlled. Therefore, the processing executed by the ECU 21 at the time of the idle stop will be described below in detail.
[0017]
When the ignition key of the vehicle is turned on and execution of idle stop is selected by a mode selection switch (not shown), the ECU 21 executes an idle stop control routine shown in FIG. 2 at a predetermined control interval. It is determined whether or not the engine stop condition is satisfied.
In the present embodiment, the engine stop condition is that the vehicle speed V detected by the vehicle speed sensor 22 is 0 km / h, that the brake switch 23 detects that the brake pedal is depressed, and that the shift position sensor 25 It is set that the detected shift position is in the N (neutral) or D (drive) range, and when these conditions are not satisfied, the ECU 21 makes a NO (negative) determination in step S2 and temporarily executes a routine. To end.
[0018]
On the other hand, if the determination in step S2 becomes YES (affirmative) due to the satisfaction of the engine stop condition, the ECU 21 proceeds to step S4 to stop the fuel injection control and the ignition timing control and stop the engine 1 (engine stop and start means). . Thereafter, it is determined in step S6 whether the engine start condition has been satisfied.
In the present embodiment, as the engine start conditions, it is set that the brake switch 23 has not detected the depression operation of the brake and that the shift position detected by the shift position sensor 25 is a driving range such as the D range. If these conditions are not satisfied, the process moves to step S8. In step S8, it is determined whether the fuel pressure Pf detected by the fuel pressure sensor 26 is equal to or higher than a predetermined value P0. For example, as the predetermined value P0, a specified pressure of the fuel line 4 adjusted by the regulator, a fuel pressure near the lower limit at which the engine can be started without any trouble, and the like are set.
[0019]
If the determination in step S8 is YES, after stopping the fuel pump 6 in step S10 (fuel pump stopping means), the process returns to step S6 and repeats steps S6 to S10. During this time, if the engine start conditions are satisfied and the determination in step S6 is YES, the ECU 21 proceeds to step S12, restarts the fuel injection control and the ignition timing control, and operates the starter generator 11 to shut down the engine 1. Ranking is performed, thereby starting the engine 1 and ending the routine.
[0020]
On the other hand, when the stop state of the fuel pump 6 in the above step S10 is continued, the fuel pressure Pf decreases very little but gradually, and when the engine stop is prolonged, the fuel pressure Pf falls below the predetermined value P0. At this time, the ECU 21 makes a NO determination in step S8, moves to step S14, drives the fuel pump 6, and then returns to step S6. Then, when the fuel pressure becomes equal to or higher than the predetermined value P0 due to the driving of the fuel pump 6, the fuel pump 6 is stopped again in step S10, and the above processing is repeated during idle stop (fuel pressure maintaining means).
[0021]
As described above, in the stop and start device for the engine 1 according to the present embodiment, the fuel pump 6 is driven and stopped while the engine is stopped at the idle stop to maintain the fuel pressure at or above the predetermined value P0. Therefore, when the engine is subsequently started, the fuel injection control is restarted under the appropriate fuel pressure Pf, and the engine 1 is started quickly. In particular, in the present embodiment, since the fuel pump 6 is controlled based on the actual fuel pressure Pf detected by the fuel pressure sensor 26, the fuel pressure Pf is reliably maintained at or above a predetermined value P0 set as an appropriate value. Quick and smooth starting can be realized with high reliability.
[0022]
As a result, particularly when a quick start is required, for example, even when waiting for a right turn to start with an eye on the oncoming vehicle at the intersection, the driver can start the vehicle without any anxiety by the quick and smooth engine start, As a result, the marketability of the idle stop vehicle can be improved.
Further, as a result of the control based on the fuel pressure Pf, the driving of the fuel pump 6 is stopped to the minimum necessary for maintaining the fuel pressure Pf at a predetermined value. As a result, unnecessary driving of the fuel pump 6 can be prevented, and power consumption by the fuel pump 6 during idle stop can be minimized. If the power consumption during idling stop is large, the power generation amount of the starter generator 11 increases after the engine starts, so that the fuel consumption of the engine 1 increases as a driving resistance, and especially the fuel consumption during acceleration deteriorates. There is also obtained an advantage that deterioration in fuel efficiency can be suppressed with a reduction in power consumption during the operation.
[0023]
The embodiment has been described above, but aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the present invention is embodied in a stop / start device for an idle stop vehicle. However, the application is not limited to this, and may be embodied in, for example, a stop / start device for a hybrid vehicle. In the hybrid vehicle, the engine is stopped and started according to the running state, the SOC of the battery, and the like. Therefore, if the same fuel pump control as in the above embodiment is executed while the engine is stopped, the power consumption by the pump drive is suppressed and the engine is started. It can be started quickly, and control in cooperation with the motor can be realized.
[0024]
Further, even when the present invention is embodied as a stop / start device for an idle stop vehicle, the types of the engine 1 and the transmission are not limited to those in the above-described embodiment. For example, the cylinder arrangement of the engine 1 is changed, or the automatic transmission is replaced. Alternatively, a manual transmission may be applied. Further, in the above embodiment, the fuel pump 6 is driven / stopped based on the fuel pressure Pf. However, the method is not limited as long as the fuel pressure Pf during the idle stop can be maintained. The fuel pump 6 may be controlled based on the performed time. That is, the fuel pressure drop characteristic of the fuel line 4 when the fuel pump 6 is stopped is determined in advance by a test, and the fuel pump 6 is driven in accordance with the timing at which the fuel pressure Pf falls below a predetermined value (for example, the predetermined value P0). While the cycle T is determined, the drive time t of the fuel pump 6 required to recover the reduced fuel pressure Pf is determined in advance, and when the determination of NO is made in step S6 of FIG. Alternatively, the fuel pump 6 may be driven for the drive time t. In the case of such a configuration, it is not necessary to provide the fuel pressure sensor 26 in the fuel line 4, and the same operation and effect as the above embodiment can be obtained at a lower manufacturing cost.
[0025]
On the other hand, in the above-described embodiment, the engine stop condition is set such that the vehicle speed is 0 km / h, the brake switch is on, and the shift position is in a travel range such as N or D, and the engine start condition is that the brake switch is off and the shift position is However, the stop condition and the start condition are not limited to these. For example, as an engine stop condition, the accelerator operation amount Acc detected by the accelerator sensor 24 is 0 (idle). Driving).
[0026]
【The invention's effect】
As described above, according to the engine stop and start device of the first aspect of the present invention, fuel consumption is improved by suppressing energy consumption by driving the fuel pump while the engine is stopped. It is possible to prevent a start failure caused by the failure beforehand and realize a quick and smooth engine start.
[0027]
According to the engine stop / start device of the second aspect of the present invention, in addition to the first aspect, the present invention can be implemented at a low manufacturing cost without requiring sensors for pump control.
According to the third aspect of the invention, in addition to the first aspect, the reliability of the fuel pump can be further improved by controlling the fuel pump based on the actual fuel pressure.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an engine stop / start device according to an embodiment.
FIG. 2 is a flowchart illustrating an idle stop control routine executed by an ECU.
[Explanation of symbols]
1 engine 6 fuel pump 21 ECU (engine stop / start means, fuel pump stop means, fuel pressure maintaining means)
26 Fuel pressure sensor (fuel pressure detecting means)

Claims (3)

A fuel pump that supplies fuel to the engine,
Engine stop and start means for stopping the engine when a predetermined stop condition is satisfied and starting the engine when a predetermined start condition is satisfied;
Fuel pump stop means for stopping the fuel pump when the engine is stopped by the engine stop / start means;
And a fuel pressure maintaining means for maintaining a pressure of the fuel supplied to the engine while the fuel pump is stopped by the fuel pump stopping means. The engine stop / start device according to claim 1, wherein the fuel pressure maintaining means drives the fuel pump at predetermined time intervals. The fuel pressure maintaining means includes fuel pressure detecting means for detecting a pressure of fuel supplied to the engine, and drives the fuel pump when the fuel pressure detected by the fuel pressure detecting means falls below a predetermined value. The engine stop / start device according to claim 1, wherein:

Images