JPH11182371A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise (pump sound) by corresponding to the demand of an engine accurately when a motor driven fuel pump is driven. SOLUTION: An actual fuel consumption amount equivalent value TPUMP= Ti/KINJ×Ne is calculated based on an injection pulse width Ti of a fuel injection valve, a fuel pressure correction coefficient KINJ based on fuel pressure supplied to the fuel injection valve, and the number of rotation of an engine Ne (S3 to S6). This actual fuel consumption amount equivalent value TPUMP is compared with a predetermined value, and a discharge flow rate of a motor driven fuel pump is changed over to a low flow rate and a high flow rate in accordance with the results of the comparison (S7 to S9). On the other hand, a discharge flow rate of the fuel pump is forcedly changed over to a high flow rate side under specific operation conditions such as the time of start and cold time (S1, S2, S9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an internal combustion engine having an electric fuel pump for supplying fuel to a fuel injection valve, and more particularly to an improvement in a control device for the fuel pump.

[0002]

2. Description of the Related Art Conventionally, as a fuel supply device for an internal combustion engine, in particular, a direct injection spark ignition type internal combustion engine, an electric low pressure fuel pump for sucking and discharging fuel in a fuel tank, and a fuel supplied from the low pressure fuel pump. Some include an engine-driven high-pressure fuel pump that suctions and discharges the fuel and supplies it to the fuel injection valve (see Japanese Patent Application Laid-Open No. 8-261094).

Here, with respect to an electric fuel pump (low-pressure fuel pump), the drive flow is varied in accordance with the engine speed so that the discharge flow rate is low in the low rotation range.
In the high rotation range, the discharge flow rate was controlled to be switched to a high flow rate.

[0004]

However, in such control of the discharge flow rate of the fuel pump according to the engine speed, the discharge flow rate of the fuel pump to be controlled does not always correspond to the required fuel amount of the engine. In order to avoid the shortage, it is necessary to set the switching speed to a relatively low rotation speed side. This caused an increase in noise (pump noise).

The present invention has been made in view of the above-mentioned conventional problems, and is intended to reduce the noise (pump noise) while appropriately responding to the demands of the engine by making the control of the fuel pump more appropriate. The purpose is to do.

[0006]

According to the first aspect of the present invention, there is provided a fuel supply apparatus for an internal combustion engine having an electric fuel pump for supplying fuel to a fuel injection valve.
And a fuel pump for controlling a discharge flow rate of the fuel pump according to the actual fuel consumption equivalent value, which calculates an actual fuel consumption equivalent value based on the engine operating state. And control means.

According to the second aspect of the present invention, an electric low pressure fuel pump for sucking and discharging fuel in a fuel tank and an engine driven type for sucking and discharging fuel from the low pressure fuel pump and supplying the fuel to a fuel injection valve are provided. In a fuel supply device for an internal combustion engine including a high-pressure fuel pump, as shown in FIG. 1, an actual fuel consumption equivalent value calculating means for calculating an actual fuel consumption equivalent value based on an engine operating state; Fuel pump control means for controlling the discharge flow rate of the low-pressure fuel pump according to the equivalent value.

In the invention according to claim 3, the actual fuel consumption equivalent value calculating means calculates the actual fuel consumption equivalent value from the injection pulse width of the fuel injection valve, the fuel pressure supplied to the fuel injection valve, and the engine speed.
It is characterized in that a value corresponding to actual fuel consumption is calculated. In the invention according to claim 4, the actual fuel consumption equivalent value calculating means includes an injection pulse width of the fuel injection valve as Ti, a fuel pressure correction coefficient based on fuel pressure as KINJ, and an engine speed as N.
When e is set, the actual fuel consumption equivalent value TPUMP is calculated by TPUMP = Ti / KINJ × Ne.

According to a fifth aspect of the present invention, the fuel pump control means switches the discharge flow rate of the fuel pump between two stages, a high flow rate and a low flow rate.
In the invention according to claim 6, as shown in FIG. 1, under a predetermined engine operating condition (specific operating condition), the discharge flow rate of the fuel pump is forcibly set to a high flow rate in preference to the fuel pump control means. And a forcible control means for controlling the side.

[0010] The invention according to claim 7 is characterized in that the forcible control means forcibly controls the discharge flow rate of the fuel pump to a high flow rate side at least at the time of starting or in a cold state. In the invention according to claim 8, the fuel is supplied from the upstream side of the high-pressure fuel pump separately from the fuel injection valve that receives the supply of fuel from the downstream side of the high-pressure fuel pump and directly injects the fuel into the combustion chamber of the engine. An auxiliary fuel injection valve for injecting fuel into the intake passage of the engine under predetermined operating conditions, and at least at the time of operation of the auxiliary fuel injection valve, giving priority to the fuel pump control means and giving a discharge flow rate of the low pressure fuel pump. Is forcibly controlled to a high flow rate side.

[0011]

According to the first aspect of the present invention, a value corresponding to the actual fuel consumption is calculated based on the engine operating state, and the discharge flow rate of the fuel pump is controlled in accordance with the calculated value. The effect is obtained that the noise (pump sound) can be reduced while responding accurately.

According to the second aspect of the invention, when an electric low-pressure fuel pump and an engine-driven high-pressure fuel pump are provided, the discharge flow rate of the low-pressure fuel pump is adjusted according to the actual fuel consumption value. The above effects can be obtained by controlling. According to the third and fourth aspects of the present invention, the actual fuel consumption equivalent value is accurately determined from the injection pulse width of the fuel injection valve, the fuel pressure supplied to the fuel injection valve, and the engine speed. And control accuracy can be improved.

According to the fifth aspect of the present invention, the control can be simplified by switching the discharge flow rate of the fuel pump between two stages, a high flow rate and a low flow rate. According to the present invention, the discharge flow rate of the fuel pump is forcibly controlled to a high flow rate side under specific operation conditions such as at the time of starting or during a cold time, so that the actual fuel is controlled. In the region where the consumption equivalent value cannot be calculated accurately or in the region where the combustion of the engine is unstable, the effect of being able to reliably avoid running out of fuel can be obtained.

According to the eighth aspect of the present invention, the function of the auxiliary fuel injection valve is fully exhibited by forcibly controlling the discharge flow rate of the low-pressure fuel pump to the high flow side when the auxiliary fuel injection valve is operated. The effect is obtained.

[0015]

Embodiments of the present invention will be described below. FIG. 2 is a system diagram of a fuel supply device for an internal combustion engine showing one embodiment of the present invention. A low-pressure fuel pump 2 and a low-pressure regulator 3 are provided in the fuel tank 1.

The low-pressure fuel pump 2 is driven by a built-in electric motor, and draws and discharges fuel in the fuel tank 1. The low-pressure regulator 3 opens when the pressure on the discharge side of the low-pressure fuel pump 2 becomes equal to or higher than the set value P1, and returns excess fuel from the discharge side of the low-pressure fuel pump 2 to the fuel tank 1. Fuel from the low-pressure fuel pump 2 is sent to the suction side of the high-pressure fuel pump 5 through the fuel supply passage 4.

The high-pressure fuel pump 5 is an engine-driven type, driven by a crankshaft (not shown) via a belt and a pulley, and sucks and discharges the fuel from the low-pressure fuel pump 2 to further increase the pressure, thereby increasing the internal combustion engine (main body). The fuel is supplied to an electromagnetic fuel injection valve (injector) 7 for each cylinder 6. Internal combustion engine 6
Denotes a direct injection spark ignition type internal combustion engine, and a fuel injection valve 7 is provided so as to inject fuel directly into a combustion chamber for each cylinder in synchronization with engine rotation.

The high-pressure regulator 8 includes a high-pressure fuel pump 5
When the pressure on the discharge side of the valve becomes equal to or higher than the set value P2 (P2> P1), the valve is opened, and excess fuel is returned to the fuel tank 1 from the discharge side of the high-pressure fuel pump 5 through the fuel return passage 9. Here, the electric low-pressure fuel pump 2 switches and controls the drive voltage by the drive circuit 11 according to a signal from the control unit 10 to make the drive voltage high, so that the discharge flow rate is high and the drive voltage is low. By using a low voltage, the discharge flow rate can be switched to a low flow rate.

Signals from various sensors (such as a crank angle sensor, an air flow meter, and a water temperature sensor) are input to the control unit 10 for controlling the internal combustion engine 6, and these signals are used to control the engine speed Ne and the intake air flow rate. Q
In addition to a, the water temperature Tw, and the like, the injection pulse width Ti of the fuel injection valve 7 calculated by these can be known. Further, a fuel pressure sensor 12 is provided for detecting a fuel pressure (pressure on the discharge side of the high-pressure fuel pump 5) Pf supplied to the fuel injection valve 7, and a signal thereof is also input.

In addition to the fuel injection valve 7, an auxiliary fuel injection valve that receives fuel from the fuel supply passage 4 upstream of the high-pressure fuel pump 5 and injects fuel into an intake passage (not shown) of the internal combustion engine 6. Cold start injector 1 as
3 is provided in the intake passage, and only at the time of low-temperature start-up when the pressure on the discharge side of the high-pressure fuel pump 5 is low or when the high-pressure fuel pump 5 or the like fails, only the cold start injector 13 injects fuel into the intake passage. I have.

The control of the discharge flow rate of the low-pressure fuel pump 2 by the control unit 10 is performed according to a flowchart (fuel pump control routine) shown in FIG. The fuel pump control routine of FIG. 3 is executed every predetermined time. In step 1 (referred to as S1 in the figure, the same applies hereinafter), ON / OFF of a start switch, water temperature Tw, and the like are read.

In step 2, it is determined whether or not a specific operating condition is satisfied. If the specific operating condition is satisfied, the process proceeds to step 9, in which the drive voltage to the low-pressure fuel pump 2 is switched to a high voltage to force the discharge flow rate. Switch to high flow side. This part (steps 1, 2, 9) corresponds to the forcible control means under specific operating conditions. The specific operating conditions referred to here are, specifically, when the start switch ON is started, when the water temperature Tw is cold, for example, lower than 10 ° C. (low water temperature), when the starting water temperature Tw is, for example, 50 ° C. or higher, and the start switch is turned on. Until a predetermined time elapses after the OFF (immediately after the high water temperature start), this corresponds to any of the following: during the detection of the water temperature sensor abnormality, during the detection of the crank angle sensor abnormality, or during the operation of the cold start injector. As a result, in a region where the actual fuel consumption equivalent value cannot be calculated accurately or in a region where combustion of the engine is unstable, shortage of fuel can be reliably avoided, and the function of the cold start injector 13 can be sufficiently reduced. Can be demonstrated.

If the specific operating condition is not satisfied, the routine proceeds to step 3. In step 3, the engine speed Ne is read. In step 4, the injection pulse width Ti of the fuel injection valve is read. In step 5, the fuel pressure Pf supplied to the fuel injection valve is read, and based on this, the fuel pressure correction coefficient KIN
Calculate J.

The fuel pressure correction coefficient KINJ is a basic injection pulse calculated based on the intake air flow rate Qa and the engine speed Ne on the assumption that the fuel pressure Pf supplied to the fuel injection valve 7 is the set value P2. When the discharge side pressure of the high-pressure fuel pump 5 is less than the set value P2, for example, immediately after the start, for example, the width Tp, the injection pulse width Ti (=) is increased by the fuel pressure correction coefficient KINJ based on the actual fuel pressure Pf, Tp
× KINJ × COEF; COEF is used for calculating various correction coefficients.

In step 6, the actual fuel consumption is calculated from the injection pulse width Ti of the fuel injection valve, the fuel pressure correction coefficient KINJ based on the fuel pressure supplied to the fuel injection valve, and the engine speed Ne by the following equation. The equivalent value TPUMP is calculated. TPUMP = Ti / KINJ × Ne Here, the reason for dividing by the fuel pressure correction coefficient KINJ is to know the actual fuel injection amount from the injection pulse width. Because you do.

In step 7, an actual fuel consumption equivalent value TP
UMP is compared with a predetermined value (threshold with hysteresis). As a result of the comparison, if the actual fuel consumption equivalent value TPUMP is small (if TPUMP <predetermined value), step 8
Then, by switching the driving voltage to the low-pressure fuel pump 2 to a low voltage, the discharge flow rate is switched to the low flow rate side. Thereby, noise (pump sound) is reduced.

Conversely, if the actual fuel consumption equivalent value TPUMP is large (if TPUMP ≧ predetermined value), step 9
Then, the discharge flow rate is switched to the high flow rate side by switching the drive voltage to the low-pressure fuel pump 2 to the high voltage. This responds to the demands of the institution. Here, steps 3 to
Step 6 corresponds to the actual fuel consumption equivalent value calculating means, and steps 7 to 9 correspond to the fuel pump control means.

As described above, the actual fuel consumption equivalent value TPUMP is calculated based on the engine operating state, and the discharge flow rate of the low-pressure fuel pump 2 is controlled in accordance with the calculated value. Noise (pump noise) can be reduced. In this embodiment, the present invention is applied to control of a low-pressure fuel pump in a direct-injection spark ignition type internal combustion engine including an electric low-pressure fuel pump and an engine-driven high-pressure fuel pump. The present invention can be generally applied to an internal combustion engine having a pump.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of a fuel supply device for an internal combustion engine, showing an embodiment of the present invention.

FIG. 3 is a flowchart of a fuel pump control routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Low pressure fuel pump 3 Low pressure regulator 5 High pressure fuel pump 6 Internal combustion engine (body) 7 Fuel injection valve 8 High pressure regulator 10 Control unit 11 Drive circuit 12 Fuel pressure sensor 13 Cold start injector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Motohiro Matsumura 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Nissan Motor Co., Ltd.

Claims (8)

[Claims] A fuel supply device for an internal combustion engine including an electric fuel pump for supplying fuel to a fuel injection valve, wherein the actual fuel consumption equivalent value is calculated based on an engine operating state. A fuel supply device for an internal combustion engine, comprising: a calculation unit; and a fuel pump control unit that controls a discharge flow rate of the fuel pump according to an actual fuel consumption equivalent value. 2. An electric low-pressure fuel pump for sucking and discharging fuel in a fuel tank, and an engine-driven high-pressure fuel pump for sucking and discharging fuel from the low-pressure fuel pump and supplying the fuel to a fuel injection valve. In a fuel supply device for an internal combustion engine, an actual fuel consumption equivalent value computing unit that computes an actual fuel consumption equivalent value based on an engine operating state; and a discharge flow rate of the low-pressure fuel pump according to the actual fuel consumption equivalent value. A fuel supply device for an internal combustion engine, comprising: fuel pump control means for controlling. 3. The actual fuel consumption equivalent value computing means computes an actual fuel consumption equivalent value from an injection pulse width of the fuel injection valve, a fuel pressure supplied to the fuel injection valve, and an engine speed. 3. The method according to claim 1, wherein
A fuel supply device for an internal combustion engine according to any one of the preceding claims. 4. The actual fuel consumption equivalent value calculating means, assuming that the injection pulse width of the fuel injection valve is Ti, the fuel pressure correction coefficient based on the fuel pressure is KINJ, and the engine speed is Ne, is the actual fuel consumption equivalent value. 4. The method according to claim 3, wherein TPUMP is calculated by TPUMP = Ti / KINJ × Ne.
A fuel supply device for an internal combustion engine according to any one of the preceding claims. 5. The fuel pump control means according to claim 1, wherein the fuel pump control means switches the discharge flow rate of the fuel pump between two stages, a high flow rate and a low flow rate. A fuel supply device for an internal combustion engine according to any one of claims 1 to 3. 6. A forcible control means for forcibly controlling the discharge flow rate of the fuel pump to a high flow rate side prior to the fuel pump control means under predetermined engine operating conditions. A fuel supply device for an internal combustion engine according to any one of claims 1 to 5. 7. The internal combustion engine according to claim 6, wherein the forcible control means forcibly controls the discharge flow rate of the fuel pump to a higher flow rate at least at the time of starting or during a cold period. Fuel supply device. 8. In addition to a fuel injection valve that receives fuel supplied from a downstream side of a high-pressure fuel pump and directly injects fuel into a combustion chamber of an engine, a predetermined amount of fuel is supplied from an upstream side of a high-pressure fuel pump. A sub-fuel injection valve for injecting fuel into an intake passage of the engine under operating conditions, wherein at least when the sub-fuel injection valve is operated, the discharge flow rate of the low-pressure fuel pump is forcibly given priority to the fuel pump control means. 3. The fuel supply device for an internal combustion engine according to claim 2, wherein a forced control means for controlling the flow rate to a higher flow rate side is provided.