JP2007107471A - Fuel supply control device for vehicle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve startability both at cold starting and at high-temperature restarting and improve emission control at starting by operating a fuel pump before starting an engine. <P>SOLUTION: This fuel supply control device for a vehicular engine drives the fuel pump before starting to increase pressure up to fuel pressure higher than normal pressure after starting (S12) when previously predicting the start of the engine (S11). This actualizes fuel injection in high fuel pressure conditions from the beginning of fuel injection at starting to improve atomizing performance at cold starting and suppress the occurrence of fuel vapor at high-temperature restarting. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel supply control device for a vehicle engine, and more particularly to a fuel pressure control technique before starting the engine.

In Patent Document 1, opening / closing of a vehicle door, insertion of a key into a key cylinder, seating of a driver, wearing of a seat belt, and the like are detected, and the engine start schedule is determined from these detection results. A start preparation system is disclosed that initiates start preparation for an engine when occurrence is determined.
As preparation for starting the engine, energization of an electric heater provided in a fuel injection valve for injecting fuel into the engine is started.
JP 2004-340028 A

  By the way, even if the fuel pump is operated based on the prediction of engine start and the fuel pressure can be increased to near the normal pressure by the time the engine start is started, the fuel atomization performance is insufficient at the time of cold start. As a result, the ignition stability of the air-fuel mixture decreases, and fuel vapor is generated near the fuel injection valve when restarting at a high temperature, resulting in a decrease in the fuel injection amount and sufficiently improving startability and emission performance at start-up. There was a problem that sometimes it could not be made.

  The present invention has been made in view of the above-mentioned problems, and is intended to improve startability and improve emissions at start-up both at cold start and at high temperature restart by operating the fuel pump before engine start. It is an object of the present invention to provide a fuel supply control device for a vehicle engine that can perform the above.

Therefore, the fuel supply control apparatus for a vehicle engine according to the first aspect of the present invention includes a start prediction unit that predicts engine start in advance, and fuel supply when the start of the engine is predicted in advance by the start prediction unit. Start preparation means for operating the means to increase the fuel pressure to a higher fuel pressure than the normal pressure after the start is provided.
According to such a configuration, the engine start is predicted in advance, and the fuel supply means is operated before the engine is started, so that the fuel pressure is increased to a fuel pressure higher than the normal pressure after the start.

Therefore, the fuel injection at the time of engine start can be performed under the fuel pressure condition higher than usual from the first injection, the fuel atomization performance is improved at the time of cold start, and the fuel at the time of high temperature restart. Vapor generation can be suppressed, startability can be improved, and emission at start-up can be improved.
According to a second aspect of the present invention, there is provided an operation prohibiting means for prohibiting the operation of the fuel supply means by the start preparation means when the voltage of a battery which is an operation power source of the fuel supply means is lower than a predetermined value. And

According to such a configuration, when the battery voltage is low, the operation of the fuel supply means is prohibited even if the engine start is predicted in advance, and the fuel supply means is normally operated when the key switch or the start switch is turned on.
Therefore, by operating the fuel supply means before starting the engine, it is possible to prevent the battery voltage from greatly decreasing, and it is possible to avoid deterioration in startability due to malfunction of the starter motor.

According to a third aspect of the present invention, there is provided a boost target variable means for varying the boost target in the start preparation means in accordance with a voltage of a battery which is an operation power source of the fuel supply means.
According to this configuration, it is determined how much pressure can be increased based on the battery voltage, and a boost target that does not greatly reduce the battery voltage is set.

Therefore, the fuel pressure can be increased to as high a pressure as possible before starting the engine within a range in which the battery voltage is not greatly reduced.
According to a fourth aspect of the present invention, there is provided injection time changing means for changing the injection time of the fuel injection valve at the start-up according to the fuel pressure when the fuel supply means is operated before the engine is started by the start preparation means. It is provided.

According to this configuration, the injection time (valve opening time) is changed in response to the change in the injection amount per unit valve opening time due to the change in the pressure of the fuel supplied to the fuel injection valve, and the pressure The required amount of fuel is injected without being affected by the difference.
Therefore, by raising the fuel pressure more than usual, it is possible to prevent the measurement accuracy of the fuel injection amount from decreasing and the air-fuel ratio to fluctuate.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of a vehicle engine in the embodiment.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103b by a throttle motor 103a is interposed in an intake pipe 102 of an engine 101 (gasoline engine).

Then, air is sucked into the combustion chamber 106 through the electronic control throttle 104 and the intake valve 105.
The intake port 130 of each cylinder is provided with an electromagnetic fuel injection valve 131, and each fuel injection valve 131 is provided with an injector heater 131a for heating the fuel.

When the fuel injection valve 131 is driven to open by an injection pulse signal from the control unit 114, the fuel injection valve 131 injects fuel adjusted to a predetermined pressure toward the intake valve 105.
The air-fuel mixture formed in the combustion chamber 106 is ignited and burned by spark ignition by a spark plug (not shown).
The combustion exhaust in the combustion chamber 106 is discharged to the exhaust pipe through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.

The intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the intake side camshaft 111 and the exhaust side camshaft 110, respectively.
The fuel tank 135 incorporates an electric fuel pump 136 (fuel supply means). By driving the fuel pump 136, fuel is pumped toward the fuel injection valve 131.
The distribution pipe 137 that distributes the fuel discharged from the fuel pump 136 to each fuel injection valve 131 is provided with a fuel pressure sensor 138 so that the fuel pressure detected by the fuel pressure sensor 138 becomes the target pressure. The discharge amount of the fuel pump 136 is feedback controlled by the control unit 114.

The control unit 114 includes a microcomputer and controls the electronic control throttle 104, the fuel injection valve 131, the injector heater 131a, the fuel pump 136, and the like by arithmetic processing based on detection signals from various sensors.
As the various sensors, in addition to the fuel pressure sensor 138, an accelerator opening sensor 116 that detects the depression amount (accelerator opening) of an accelerator pedal operated by a driver, and an air flow meter 115 that detects an intake air amount Q of the engine 101. A crank angle sensor 117 that detects the rotational position of the crankshaft 120, a throttle sensor 118 that detects the opening TVO of the throttle valve 103b, a water temperature sensor 119 that detects the coolant temperature of the engine 101, and the upstream side of the front catalyst 108. An air-fuel ratio sensor 121 with a heater for detecting the exhaust air-fuel ratio based on the oxygen concentration in the exhaust gas is provided.

By the way, the control unit 114 has a function of predicting engine start in advance and preparing for engine start prior to engine start by an operation of an ignition key or a start button by a driver, that is, a start predicting means, It has a function as a start preparation means, and the start preparation for the engine will be described below.
The control unit 114 may be divided into, for example, a unit that controls the engine and a unit that performs engine start prediction and commands engine start preparation.

The flowchart of FIG. 3 shows a first embodiment of start preparation control.
In the flowchart of FIG. 3, first, in step S <b> 11, the start of the engine is predicted in advance by detecting the occupant's boarding or boarding intention.
The occupant's boarding or boarding intention is detected based on, for example, the following motion detection, determination of system status, authentication, and the like.
(1) Opening / closing of vehicle door (2) Unlocking door with key or remote control (3) Verification of ID signal of remote controller (4) Insertion of key into ignition key cylinder (5) Insertion of key into keyhole of door ( 6) Seating on the driver's seat (7) Wearing a seat belt in the driver's seat (8) Canceling the anti-theft system (9) Detection of moving objects around the vehicle (10) Personal authentication It is used to identify whether or not the person who has indicated his / her intention is one or more of those registered in advance. For example, release of the anti-theft system, automatic unlocking of the door, auto seat position, driving It is used for automatic change control of characteristics, automatic confirmation of driving qualifications and driving history.

And personal authentication is performed based on biometric authentication such as a fingerprint, property authentication such as a driver's license, knowledge authentication using a password, etc., and when authenticated as a pre-registered person, A specific driver's boarding or willingness to board is judged and it is predicted that the engine will be started.
However, the detection method of the occupant's boarding or boarding intention is not limited to the above, and the method for predicting the start of the engine in advance is limited to the method based on the detection of the boarding or boarding intention of the occupant. is not.

As shown in FIG. 2, the control unit 114 includes a door switch 81, a personal authentication device 82, a seating sensor 83, a seat belt switch 84, etc., as shown in FIG. The detection signal is input.
If the engine start is predicted in advance in step S11, the process proceeds to step S12, and energization of the fuel pump 136 is started and rotationally driven as preparation for starting.

Here, in the operation control of the fuel pump 136 in step S12, the operation of the fuel pump 136 is continued until the fuel pressure detected by the fuel pressure sensor 138 reaches the target pressure, but the target pressure is higher than the normal pressure after starting. A high value is set, and the pressure is increased to a pressure higher than the normal pressure after starting before starting the engine.
Since fuel injection is not performed before the engine is started, when the target pressure is reached, the operation of the fuel pump 136 is temporarily stopped.

  As described above, if the pressure is raised to a fuel pressure higher than usual before starting the engine, fuel injection is performed under a pressure condition higher than usual from the first injection when the engine is started. The fuel atomization performance is improved during cold start, and the generation of fuel vapor can be suppressed during high temperature restart, thereby improving startability and emission during start-up.

The target pressure in the drive control of the fuel pump 136 as the preparation for starting is set to be higher than the normal pressure after starting only when the engine is cold and restarting at a high temperature. The subsequent normal pressure can be set as the target pressure.
In preparation for starting, the fuel pump 136 is operated, and at the same time, energization of the heaters of the injector heater 131a and the air-fuel ratio sensor 121 is started, and the operation of the electric oil pump 141 is started. Can do.

If the injector heater 131a is energized in advance and the heater temperature is raised, atomization of fuel spray can be promoted from the start of startup.
Also, if the heater of the air-fuel ratio sensor 121 is energized in advance, the element temperature of the air-fuel ratio sensor 121 can be raised to the activation temperature or close to the activation temperature before starting the start, and the air-fuel ratio feedback control is performed. Can be started earlier.

Furthermore, if the electric oil pump 141 is operated in advance, the oil pressure can be increased in advance before the engine is actually started, and the oil circulation and the like can be performed satisfactorily.
In step S13, it is determined whether or not the ignition key switch is turned on.
When the ignition key switch is turned on, the process proceeds to step S14, where the electronic control throttle 104, fuel injection valve 131, injector heater 131a, fuel pump 136, etc. are controlled normally.

However, immediately after the start and immediately after the start of the fuel injection under the fuel pressure higher than the normal by the start preparation control, the injection amount per unit valve opening time of the fuel injection valve 131 is higher than when the injection is performed at the normal fuel pressure. Become more.
Therefore, the injection time is corrected according to the fuel pressure detected by the fuel pressure sensor 138 so that the required amount of fuel is injected even under high fuel pressure conditions (injection time changing means).

Thus, by increasing the fuel pressure, it is possible to prevent the fuel injection amount from being measured accurately and the air-fuel ratio from fluctuating.
Here, in the control of the fuel pump 136 after the key switch is turned on, for example, until the coolant temperature (engine temperature) reaches a predetermined temperature or for a predetermined time from the start based on the same target pressure as that at the start preparation. The fuel pump 136 can be feedback-controlled. In this case as well, the fuel measurement accuracy can be ensured by correcting the injection time according to the fuel pressure higher than usual.

When the fuel pump 136 and other devices are operated based on the engine start prediction, if the engine is not started (key switch is turned on) within a predetermined time, the operation is temporarily canceled.
By the way, in the start preparation control described above, since the fuel pump 136 is operated using the battery 140 as a power source in a state where power generation by the alternator is not performed, there is a possibility that the battery voltage is greatly reduced.

Therefore, in the second embodiment shown in the flowchart of FIG. 4, execution / non-execution of the start preparation for operating the fuel pump 136 before the engine start is switched according to the battery voltage.
In the flowchart of FIG. 4, in step S21, the start of the engine is predicted in advance by detecting the occupant's boarding or intention of boarding in the same manner as in step S11.

If the engine is predicted to start, the process proceeds to step S22 to determine whether or not the battery voltage VB at that time is equal to or higher than a predetermined value.
If the battery voltage VB is equal to or higher than the predetermined value, the process proceeds to step S23, and the fuel pump 136 is driven to increase the fuel pressure to a higher fuel pressure than the normal value after starting, similarly to step S12.

On the other hand, when the battery voltage VB is less than the predetermined value, the process skips step S23 and does not drive the fuel pump 136 as a preparation for starting (operation prohibiting means).
When the injector heater 131a, the air-fuel ratio sensor 121, and the electric oil pump 141 are operated together with the fuel pump 136 as a preparation for starting, these devices are also not operated.

If the operation of the fuel pump 136 (and other devices) before starting the engine is prohibited when the battery voltage is low as described above, the battery voltage can be prevented from dropping significantly, and the drive voltage of the starter motor can be secured. Cranking performance can be maintained.
As described above, when the engine start is predicted in advance, it is determined whether or not to prepare for the start according to the battery voltage, and after the key switch is turned on, the normal control (including the correction of the injection time according to the fuel pressure) is performed. (Steps S24, 25).

In the above-described embodiment, it is determined whether or not to perform start preparation according to the battery voltage. However, if the battery voltage is low, the target pressure in the drive control of the fuel pump 136 is lowered accordingly, and the fuel required for boosting is determined. By reducing the discharge amount, it is possible to avoid a significant drop in battery voltage.
The flowchart of FIG. 5 shows a third embodiment configured as described above.

In the flowchart of FIG. 5, in step S31, in the same manner as in step S11, the start of the engine is predicted in advance by detecting the occupant's boarding or intention to board.
If the engine is predicted to start, the process proceeds to step S32 to determine whether or not the battery voltage VB at that time is equal to or higher than a predetermined value.
If the battery voltage VB is equal to or higher than the predetermined value, the process proceeds to step S33, and the fuel pump 136 is driven to increase the fuel pressure to a higher fuel pressure than the normal value after starting, similarly to step S12.

On the other hand, when the battery voltage VB is less than the predetermined value, the process proceeds to step S34, where the target fuel pressure is corrected to be lower as the battery voltage is lower (pressure increase target variable means), and the fuel is increased to the target pressure. The drive of the pump 136 is controlled.
When the fuel pump 136 is operated with a target at a high fuel pressure in a state where the battery voltage is low, the amount of fuel required to reach the target pressure is large and the power consumption increases, so the battery voltage is greatly reduced. there is a possibility.

Therefore, the target pressure is corrected downward as the battery voltage is lower, so that the battery voltage does not drop so as to affect the starting.
As described above, when the engine start is predicted in advance, if the start preparation is performed based on the target pressure corresponding to the battery voltage, the normal control (the injection time correction corresponding to the fuel pressure is corrected) after the key switch is turned on. (Step S35, 36).

  Furthermore, in the fourth embodiment shown in the flowchart of FIG. 6, when the battery voltage is equal to or higher than the first predetermined value, the fuel pump 136 is normally controlled for start preparation, and the second lower than the first predetermined value. When it is below the predetermined value, the start preparation control of the fuel pump 136 is prohibited, and when the voltage is between the first predetermined value and the second predetermined value, the target pressure is lowered as the battery voltage is lowered. The start preparation control 136 is performed.

In the flowchart of FIG. 6, in step S <b> 41, in the same manner as in step S <b> 11, the start of the engine is predicted in advance by detecting the rider's boarding or boarding intention.
If the engine start is predicted, the process proceeds to step S42, and it is determined whether or not the battery voltage VB at that time is equal to or higher than a first predetermined value.
If the battery voltage VB is greater than or equal to the first predetermined value, the process proceeds to step S43, and the fuel pump 136 is driven to increase the fuel pressure to a higher fuel pressure than the normal value after startup, as in step S12.

On the other hand, when the battery voltage VB is less than the first predetermined value, the process proceeds to step S44, and it is determined whether or not the battery voltage VB is equal to or lower than a second predetermined value lower than the first predetermined value.
If the battery voltage VB is less than or equal to the second predetermined value, the start preparation for operating the fuel pump 136 is not performed by bypassing steps S43 and S45.
On the other hand, when the battery voltage VB exceeds the second predetermined value, that is, when the battery voltage VB is less than the first predetermined value and exceeds the second predetermined value, the process proceeds to step S45. The target pressure is corrected to be lower as the battery voltage VB is lower, and the start preparation control of the fuel pump 136 is performed.

As described above, when the start of the engine is predicted in advance, if the start preparation control of the fuel pump 136 is executed or not executed according to the battery voltage VB, and further, the target pressure is set, the key switch After the ON, the control shifts to normal control (including correction of the injection time according to the fuel pressure) (steps S46, 47).
According to the above-described embodiment, the start preparation control of the fuel pump 136 avoids the battery voltage VB from dropping to such an extent that the engine start is hindered. If the battery voltage VB has a margin, the margin is accommodated. Thus, the start preparation control of the fuel pump 136 is performed, so that the startability can be improved and the emission at the start can be improved.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) In the fuel supply control device for a vehicle engine according to any one of claims 1 to 4,
The fuel supply control device for a vehicle engine, wherein the start prediction means predicts start of the engine based on personal authentication of the occupant.

According to such a configuration, in order to specify an occupant (driver) for the vehicle, whether or not the occupant is a pre-registered person, for example, biometric authentication using a fingerprint or the like, property authentication using a driver's license, etc. Is based on knowledge authentication using a password and the like, and when it is recognized that the person is registered in advance, it detects the boarding or the intention of boarding and predicts the start of the engine.
(B) In the fuel supply control device for a vehicle engine according to any one of claims 1 to 4,
A fuel supply control device for a vehicle engine, wherein the start preparation means operates, together with the fuel supply means, at least one of a heater for a fuel injection valve, a heater for an air-fuel ratio sensor, and an electric oil pump. .

According to this configuration, the atomization of the fuel spray can be promoted from the start of the start by energizing the heater of the fuel injection valve, and the start of the air-fuel ratio feedback control can be accelerated by energizing the heater of the air-fuel ratio sensor. Furthermore, by operating the oil pump in advance, it becomes possible to increase the oil pressure to the desired pressure before the start of the engine, and to demonstrate high operability from the beginning of the engine. it can.
(C) In the fuel supply control device for a vehicle engine according to claim 1,
When the voltage of the battery that is the operating power source of the fuel supply means exceeds a second predetermined value that is less than the first predetermined value and lower than the first predetermined value, the boost target in the start preparation means is set to the voltage of the battery. The step-up target variable means for changing to a lower value as the
An operation prohibiting means for prohibiting the operation of the fuel supply means by the start preparation means when the voltage of the battery is equal to or lower than the second predetermined value;
A fuel supply control device for a vehicle engine, comprising:

  According to such a configuration, if the battery voltage is equal to or lower than the second predetermined value, it is determined that it is impossible to operate the fuel supply means from before the start while maintaining the battery voltage at which startability can be ensured. If the first predetermined value higher than the second predetermined value is exceeded without preparing the start of the means, the fuel supply means is prepared to start at a desired high pressure, and further, the first predetermined value is set. When the battery voltage is between the first predetermined value and the second predetermined value, the target pressure in the fuel supply means is reduced and the engine is operated before the engine is started.

Therefore, it is possible to increase the fuel pressure to a level as close as possible to the required level before starting the engine while avoiding the battery voltage from decreasing to such an extent that the startability is deteriorated.
(D) In the fuel supply control device for a vehicle engine according to claim 1,
The starting preparation means operates the fuel supply means by setting the target pressure higher than the normal pressure after starting when the engine is cold and restarted at a high temperature, and otherwise the target pressure is A fuel supply control device for a vehicle engine, wherein the fuel supply means is operated at a normal pressure.

  According to such a configuration, the fuel supply means is operated from before the engine start based on the high target pressure only at the time of cold operation and high temperature restart, which are operating conditions that require high fuel pressure, so that the pressure is unnecessarily high at room temperature. Can be prevented from being boosted up to

The system diagram of the engine for vehicles in an embodiment. The system figure of the control unit in an embodiment. The flowchart which shows 1st Embodiment of starting preparation control of a fuel pump. The flowchart which shows 2nd Embodiment of starting preparation control of a fuel pump. The flowchart which shows 3rd Embodiment of the starting preparation control of a fuel pump. The flowchart which shows 4th Embodiment of the start preparation control of a fuel pump.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 81 ... Door switch, 82 ... Personal authentication apparatus, 83 ... Seating sensor, 84 ... Seat belt switch, 101 ... Engine, 104 ... Electronic control throttle, 114 ... Control unit, 131 ... Fuel injection valve, 131a ... Injector heater, 135 ... Fuel tank 136 ... Fuel pump 138 ... Fuel pressure sensor 140 ... Battery

Claims (4)

In a vehicle engine provided with a fuel supply means for supplying fuel to a fuel injection valve,
Start prediction means for predicting the start of the engine in advance;
Start preparation means for operating the fuel supply means when engine start is predicted in advance by the start prediction means, and raising the fuel pressure to a fuel pressure higher than the normal pressure after the start;
A fuel supply control device for a vehicle engine, comprising: 2. An operation prohibiting means for prohibiting the operation of the fuel supply means by the start preparation means when a voltage of a battery as an operating power source of the fuel supply means is lower than a predetermined value. Fuel supply control device for vehicle engine. 2. The fuel supply for a vehicle engine according to claim 1, further comprising boost target variable means for changing a boost target in the start preparation means according to a voltage of a battery which is an operation power source of the fuel supply means. Control device. When the fuel supply means is operated before the engine is started by the start preparation means, an injection time changing means for changing the injection time of the fuel injection valve at the start according to the pressure of the fuel is provided. The fuel supply control device for a vehicle engine according to any one of claims 1 to 3.