JPS6340926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine in which injection valves are provided upstream and downstream of an intake passage of the engine to control the supply of fuel according to the operating state of the engine. This invention relates to fuel supply systems, and particularly to measures to improve restartability when the engine is warm.

(Prior Art) Generally, it is difficult to accurately control the supply of fuel to an engine over a wide range from idle operation to high-load operation using a single injection valve. Therefore, conventionally, for example,
As shown in Publication No. 54-53718, two injection valves, a first and a second injection valve, are provided in the intake passage, and these two injection valves are used depending on the operating condition of the engine,
During low load operation, fuel is injected from the first injection valve,
A system has been proposed in which the fuel is injected from the second injection valve during high-load operation to accurately control the supply of fuel over the entire operating range.

In such a fuel supply device,
The first injector, which operates during low-load operation, is positioned downstream of the intake passage close to the combustion chamber of the engine to ensure good fuel response and combustion stability during low-load operation. 2nd one activated when driving
It is desirable that the injection valve face upstream of the intake passage in order to promote atomization of the fuel during high-load operation and improve mixing with intake air to improve combustibility and output performance.

However, in this case, the first injection valve, which operates during low-load operation, is located downstream of the intake passage and close to the combustion chamber of the engine, so when the engine is warmly restarted, it receives heat from the engine. Perflation occurs in the fuel of the first injector and air bubbles are mixed into the fuel, resulting in a problem that a predetermined amount of fuel is not supplied and the air-fuel ratio becomes lean, resulting in poor restartability. Note that during normal operation after restart, the first injection valve is cooled by the intake air flow, so the perforation phenomenon is prevented.

(Object of the Invention) In view of the above, an object of the present invention is to supply fuel from the injection valve upstream of the intake passage at the time of warm restart of the engine, so that an appropriate amount of fuel can be supplied without causing perforation due to the thermal influence of the engine. The objective is to supply enough fuel to improve restartability when the engine is warm.

(Structure of the invention) In order to achieve the above object, the structure of the present invention is as follows.
As shown in FIG. 1, a first injection valve 13 for injecting fuel during low load operation is provided downstream of the intake passage 3, and a second injection valve 13 for injecting fuel during high load operation is provided upstream of the intake passage 3. The prerequisite is an engine fuel supply system equipped with a control means for controlling the supply of fuel by facing the valve 14, and a temperature detection means for detecting the temperature of the engine 1 or the ambient temperature thereof, and the engine. a start detection means for detecting the start of the first injector 1, and a start control signal that receives the signals from the temperature detection means and the start detection means and causes the second injection valve 14 to supply fuel when the engine temperature is equal to or higher than a predetermined value and when the engine is started. and a start control means for outputting the same to the control means. As a result, when the engine temperature is equal to or higher than a predetermined value and the engine is started, that is, when the engine is restarted during a warm restart, the control means receives a start control signal from the start control means and controls the control means to inject the second injection valve 14 upstream of the intake passage. It is designed to supply fuel by injection.

(Effects of the Invention) Therefore, according to the present invention, in the fuel supply system for an engine in which injection valves are provided upstream and downstream of the intake passage as described above, when the engine is warm restarted, the injection valve upstream of the intake passage is Since the fuel is supplied from the valve, it is possible to minimize the effects of heat on the engine and supply the appropriate amount of fuel, thereby improving restartability when the engine is warm. .

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings from FIG. 2 onwards.

FIG. 2 shows an embodiment in which the present invention is applied to a dual induction type engine. In the figure, 1 is the engine, 2 is the combustion chamber of the engine 1, and 3 is the combustion chamber of the engine 1.
is an intake passage for supplying intake air to the combustion chamber 2 of the engine 1; the intake passage 3 is branched into a low-load intake passage 4 and a high-load intake passage 5; 4 independently communicates with the combustion chamber 2 via a low-load intake port 6, and the high-load intake passage 5 communicates with the combustion chamber 2 via a high-load intake port 7, respectively. Further, a low-load throttle valve 8 is disposed in the low-load intake passage 4, which opens in response to an increase in engine load and fully opens when a predetermined load is reached to control the amount of intake air during low-load operation. On the other hand, the high-load intake passage 5 is provided with a high-load throttle valve 9 that opens when the engine load exceeds the predetermined load to control the amount of intake air during high-load operation. . Therefore, during low-load operation of the engine, intake air is supplied to the engine 1 only from the low-load intake passage 4, thereby increasing the intake air flow velocity and improving combustibility, while during high-load operation, intake air is supplied from the high-load intake passage 5 to the engine 1. The dual induction system is designed to improve output by increasing intake air filling efficiency by supplying intake air to the engine. still,
10 is an air cleaner, and 11 is an exhaust passage communicating with the combustion chamber 2 via an exhaust port 12.

A first injection valve 13 for injecting fuel during low-load operation is installed downstream of the low-load throttle valve 8 in the low-load intake passage 4 and closer to the engine 1. A second injection valve 14 is installed upstream of the intake passage 5 and downstream of the high-load throttle valve 9 to inject fuel during high-load operation, thereby ensuring good fuel response during low-load operation. This is intended to improve combustion stability, while promoting atomization of fuel during high-load operation and improving mixing with intake air to improve combustibility and output performance.

The first injection valve 13 and the second injection valve 14 are
It is connected to a fuel tank 17 via a fuel supply passage 16 with a fuel pump 15 interposed therebetween, and
The fuel tank 17 is connected to the fuel tank 17 through a return passage 18, and the fuel pump 15 supplies the fuel in the fuel tank 17 to each injection valve 13, 14 through the fuel supply passage 16, and the excess fuel is sent through the return passage 18. After that, the fuel is returned to the fuel tank 17. Further, a pressure regulator 19 is interposed in the middle of the return passage 18. The pressure regulator 19 has a fuel chamber 19b and a load chamber 19c partitioned by a diaphragm 19a, and the fuel chamber 19b has an inlet 19d communicating with the upstream side of the return passage 18 and a return port 19d. Outlet 1 communicating with the downstream side of the passage 18
9e is open, a valve body 19f for opening and closing the outlet 19e is supported on the diaphragm 19a, and a spring 19g is compressed in the negative pressure chamber 19c. The low load throttle valve 8 of the low load intake passage 4 is connected to the first injection valve 13 upstream through the pressure introduction passage 20, and the low load intake passage 4 is introduced into the negative pressure chamber 19c. Diaphragm 1 according to the intake negative pressure downstream of low-load throttle valve 8 and the spring force of spring 19g.
9a, and the valve body 19f opens and closes the outlet 19e to control the amount of fuel returned, thereby keeping the differential pressure between the fuel pressure and the intake negative pressure constant (the spring force of the spring 19g). This is done to eliminate fluctuations in the fuel injection amount due to the influence of intake negative pressure and to maintain the fuel injection amount per unit time from each injection valve 13, 14 constant. A first opening/closing valve 21 is interposed in the middle of the negative pressure introducing passage 20 and opens and closes to allow and block introduction of intake negative pressure into the negative pressure chamber 19c. Note that 22 and 23 are a pulsation damper and a fuel filter, respectively, which are provided in the fuel supply passage 16.

Further, the high-load intake passage 5 is provided with a bypass passage 24 that bypasses the high-load throttle valve 9, and a second on-off valve 25 for opening and closing the bypass passage 24 is interposed in the middle of the bypass passage 24. Even during low-load operation, the bypass communication 24 is opened by the opening operation of the second on-off valve 25, and intake air can also be supplied from the high-load intake passage 5, allowing fuel to be supplied from the second injection valve 14. I have to.

Under the above configuration, the first injection valve 13, the second injection valve 14, the first on-off valve 21, and the second on-off valve 25 are connected to a control unit 26 consisting of a microcomputer or the like, and their operation is controlled. The control unit 26 controls the engine speed N based on the ignition pulse, the throttle opening θ based on the opening of the low-load throttle valve 8, the shift position of the transmission, the intake air amount U, and the intake air temperature as the engine ambient temperature. Each signal of t is input.

Next, the operation of the control unit 26 will be explained with reference to the flowchart of _FIG .
1 is closed to cut off the negative pressure signal to the pressure regulator 19 so that the desired fuel injection amount can be set, and then in the second step _S2 , fuel injection is performed to ensure a good start. The fixed injection amount T is calculated and determined. Next, the third step
In _S3 , it is determined whether the intake air amount t is greater than 65℃, and if t≦65℃ (NO), it is determined that the engine is starting when the engine is cold, and the fourth step is started.
In _S4 , the first injection valve 13 is controlled to supply a fixed injection amount T of fuel, while if t>65°C (YES), the engine is started in a warm state (that is, restarted). In the fifth step _S5 , the second on-off valve 25 is opened to open the bypass passage 24 and the first injection valve 13 is opened.
T/2 fuel from the second injection valve 14 and T/2 fuel from the second injection valve 14.
The fuel is controlled to be supplied respectively, and the process moves to the sixth step _S6 . This sixth step
In step _S6 , it is determined whether the starter switch is in the ON state or not. If the answer is YES, which means that the starter switch is in the ON state, that is, if cranking is still in progress, the process returns to the first step _S1 and the above operation is repeated, while the starter switch is turned off. but
In the case of OFF (NO), in other words, after constant detonation, proceed to the next seventh step _S7 .

Then, first set the flag in the seventh step _S7 .
After turning OFF and starting the timer measurement of time τ, the engine speed N, throttle opening θ, shift position, intake air amount U, and intake temperature t at that time are read in the eighth step _S8 , and then in the ninth step S8. In step _S9 , the basic injection amount T _B is determined based on the engine speed N and intake air amount U, and the 10th
The process advances to step _S10 , and in a tenth step _S10 , it is determined whether or not the flag is in the OFF state. If this determination is NO, that is, if the flag is in the ON state, it is determined that 60 seconds or more have passed since the complete explosion, and the process moves to the 11th step _S11 . On the other hand, if the above flag is OFF (YES), it is determined in the twelfth step _S12 whether or not the timer time τ has passed 60 seconds or more.
At the 13th step _S13 , the flag is turned ON and time measurement by the timer is stopped, and then the process goes to the 11th step _S11 , and when τ<60 seconds (NO), the intake temperature t is set to 45°C at the 14th step _S14 . If t<45°C (YES), it is determined that the engine is cold, and the process proceeds to the eleventh step _S11 .

In this way, if more than 60 seconds have passed after the engine has completely exploded, or if it has not passed but the engine is cold,
After setting the basic injection amount T _B to the fixed injection amount T in the 11th step _S11 , the process proceeds to the 15th step _S15 to determine whether the engine is in a high load operating state based on the throttle opening θ and the intake air amount U. determine whether
In the case of NO, which is a low load operating state, control is performed to supply the fixed injection amount T of fuel from the first injector ₁₃ at the 11th step _S11 in the 16th step S16, and the process proceeds to the 8th step _S8 . On the other hand, under high load operation
If YES, the 1st injector 1 is activated in step _S17 .
3 to T/2 fuel from the second injection valve 14 to T/2 from the second injection valve 14.
Control is performed so that the two fuels are supplied respectively, and the process returns to the eighth step _S8 .

On the other hand, within 60 seconds after the engine complete explosion, and the above 14th
If the determination in step _S14 is NO with t≧45℃,
In the 18th step _S18 , the value obtained by multiplying the basic injection amount T _B by 1.2 is set as the fixed injection amount T, and then in the 19th step
In _S19 , it is determined whether the intake temperature t is greater than 65℃, and when t≦65℃ NO (that is, 45℃≦t≦65
℃), it is further determined in the 20th step _S20 whether or not the engine is in an idling state based on the engine speed N and the throttle opening θ, and when the answer is NO that the engine is not in an idling state, the process directly proceeds to the 15th step _S15 . When YES is the idle operating state, it is determined that it is necessary to supply the desired fuel injection amount in order to ensure combustion stability, and in the 21st step _S21 , the first on-off valve 21 is switched on. After closing the negative pressure signal to the pressure regulator 19, the process proceeds to the 15th step _S15 .
Thereafter, the operations from the 15th step onwards are performed.

On the other hand, if t>65℃ (YES),
It is determined that the engine is warm, and the 22nd step is started.
After closing the first on-off valve 21 at _S22 and cutting off the negative pressure signal to the pressure regulator 19,
In step _S23 , it is determined whether the shift position is in the neutral range or not, and if NO is not in the neutral range, that is, during normal operation, the process proceeds to the 15th step _S15 , whereas if the shift position is in the neutral range.
If YES, it is determined that the engine is in a warm restart state, and in the 24th step _S24 , the second on-off valve 25 is opened to open the bypass passage 24, and then the above-mentioned
17 Step S Proceed to ₁₇ and install the first injector 1 as described above.
3 to T/2 fuel from the second injection valve 14 to T/2 from the second injection valve 14.
Control is performed so as to supply each of the two fuels. With the above, one cycle of the control flow is completed, and thereafter the process returns to the eighth step _S8 to repeat the same operation. Thus, it constitutes a control means that controls the first and second injection valves 13 and 14 to control fuel supply according to the operating state of the engine 1, and is also configured to detect the starting of the engine 1. and a start control means configured to output a start control signal for supplying fuel not only from the first injection valve 13 but also from the second injection valve 14 to the control means when the engine is started when the engine is warm. It consists of

Therefore, for startability when the engine is warm (that is, at the time of restart), fuel is supplied from the first injection valve 13 disposed downstream of the low-load intake passage 4, and fuel is supplied from the first injection valve 13 disposed downstream of the low-load intake passage 5. Since fuel can also be supplied from the second injection valve 14 arranged upstream of the fuel injection valve, lean air-fuel ratio due to perforation phenomenon caused by supplying the entire amount of fuel from the downstream first injection valve 13 can be suppressed as much as possible. As a result, a substantially appropriate air-fuel ratio can be ensured, and restartability at warm times can be improved while ensuring good fuel response.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, in the above embodiment, fuel is supplied from both injection valves 13 and 14 at the time of warm restart, but it is of course possible to supply fuel only from the second injection valve 14. It is.

Further, in the above embodiment, the intake air temperature t is detected as the engine temperature detection means, but the engine temperature may be directly detected, or the ambient temperature may also be detected.

Further, in the above embodiment, a dual induction type engine has been described, but the present invention can be similarly applied to various types of engines, such as those equipped with a single intake passage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIGS. 2 and 3 show embodiments of the present invention, and FIG. 2 is an overall schematic diagram.
FIG. 3 is a flowchart illustrating the operation of the control unit. DESCRIPTION OF SYMBOLS 1...Engine, 3...Intake passage, 4...Intake passage for low load, 5...Intake passage for high load, 13...First injection valve, 14...Second injection valve, 26...Control unit.

Claims (1)

[Claims] 1. A first injection valve that injects fuel during low-load operation is placed downstream of the intake passage, and a second injection valve that injects fuel during high-load operation is placed upstream of the intake passage to control fuel supply. In an engine fuel supply device comprising a control means, a temperature detection means for detecting the engine temperature or the ambient temperature thereof, a start detection means for detecting the start of the engine, and a signal from the temperature detection means and the start detection means are received. A fuel supply device for an engine, characterized in that the engine temperature is equal to or higher than a predetermined value and startup control means outputs to the control means a startup control signal for supplying fuel from the second injection valve at the time of starting the engine.