JPH0224927Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an electronically controlled fuel injection device for an engine, and particularly to a fuel injection device that controls an increase in fuel at the time of starting.

(Prior Art) Generally, in an engine equipped with an electronically controlled fuel injection device, in order to obtain good startability, the fuel injection amount is increased when the engine is started. That is, as shown in FIG. 7 1, during cranking from t ₀ when the ignition switch is turned ON to start the engine until t ₁ when the engine is fully detonated, the injection amount is increased as shown in region A to promote ignition. is larger than the basic injection amount (increase ratio = 1) (increase ratio P ₁
>1) In addition to increasing the injection amount at startup, after complete explosion, in addition to the basic injection amount shown in area B, the injection amount is increased at startup to prevent engine rotation fluctuations due to sudden changes in injection amount. From the value, the basic injection amount is multiplied by a predetermined time T (t ₂ - t ₁ ) so that it decreases.
The amount is increased after starting as shown in region C.

On the other hand, when the engine is idling, as shown in, for example, Japanese Utility Model Publication No. 57-26035, an idling amount increase is performed to stabilize the idling speed, in addition to the above-mentioned amount increase control at the time of starting.
This increases the amount of fuel by a predetermined amount from the time the engine fully explodes until the engine is released from idling by opening the throttle valve. Therefore, when the engine shifts from starting to idling, this idle increase is added to the basic injection amount B and the post-start increase C, as shown by area D in FIG.

However, in the past, as shown in FIG. 7, the idle amount was increased rapidly from zero to a predetermined increase value (increase achievement rate 100%) at the time of complete engine explosion, _t1 . In Figure 1, the symbol x
As shown in , the increase ratio increases rapidly from P ₁ to P ₂ immediately after the complete explosion. Therefore, the fuel that had adhered to the intake passage during cranking suddenly vaporizes and is sucked into the combustion chamber immediately after the complete explosion, and this causes the air-fuel ratio of the mixture to temporarily exceed the temperature immediately after the complete explosion. As a result, as shown by the symbol y in Fig. 7, the engine speed temporarily drops immediately after a complete explosion, causing unpleasant engine vibrations, or in severe cases, the engine stalls. There were some problems such as

In contrast, as shown in Fig. 7, the fuel increase ratio immediately after complete explosion is the basic injection amount B' plus the post-start increase C' and idle increase D' during cranking. Increase ratio P ₁ of hourly increase A′
It is possible to set it to match the
In this way, when the throttle valve is opened and the idle increase D' is canceled immediately after a complete explosion, the increase ratio changes from the value P ₁ due to the starting increase A' to the basic injection amount B' and the post-start increase C'. The value suddenly drops to P ₃ due to the increase in fuel consumption, resulting in engine vibration and engine stalling due to insufficient increase in fuel volume.

(Purpose of the invention) This invention addresses the above-mentioned problems with conventional electronically controlled fuel injection systems, and by appropriately controlling the increase in idle volume, the engine speed can be temporarily reduced immediately after the engine completely explodes. The purpose of the present invention is to prevent engine slump, accompanying vibration, engine stalling, etc., and to realize an engine with excellent startability. In particular, in the present invention, in an engine in which the increase ratio of the start-up increase during cranking is variably controlled according to the engine temperature, when the increase ratio is increased at a low temperature of the engine, the idle increase is added immediately after complete combustion. The purpose of this invention is to prevent the air-fuel ratio from becoming overrich due to the above-mentioned conditions, thereby improving the operating condition of the engine during the transition from starting to idling.

(Structure of the invention) The electronically controlled fuel injection device according to the invention is characterized by having the following structure in order to achieve the above object.

That is, as shown in the block diagram in FIG. 1, the fuel injection device receives signals from an intake air amount sensor 1 and an engine rotation speed sensor 2, and performs basic injection of fuel according to the intake air amount and engine rotation speed. basic injection amount setting means 3 for setting the amount; starting increasing amount setting means 5 for receiving a signal from the engine temperature sensor 4 during cranking and setting the injection amount to a larger value as the engine temperature is lower; and a complete combustion sensor 6. post-start increase setting means 7 for gradually decreasing the injection amount set by the start-up increase setting means 5 to the basic injection amount over a predetermined period when a complete engine explosion is detected by a signal from the engine; Throttle sensor 8 from time
an idle increase setting means 9 for gradually increasing the increase value from zero to a predetermined increase value over a set time within the predetermined time during idling until the throttle valve is opened, which is detected by a signal from the engine; , an idle increase correction means 10 that receives a signal from the temperature sensor 4 and lengthens the set time as the engine temperature is lower to make the rising slope of the idle increase gentler.

According to such a configuration, when cranking the engine, fuel is supplied at the injection amount set by the starting amount increase setting means 5 so that the injection amount becomes larger as the engine temperature becomes lower, and after the engine completely explodes, In this case, the injection amount increased during cranking is reduced to the basic injection amount over a predetermined period of time by the after-start increase setting means 7. At this time, an idle increase is also performed by the idle increase setting means 9, but since this idle increase is gradually increased from zero to a predetermined increase value over a set time within the above-mentioned predetermined time, the idle increase is performed immediately after the complete explosion. This prevents the engine speed from dropping as shown in FIG. 7 due to the sudden addition of the increased amount. In addition, since the rise time of this idle increase (the above-mentioned set time) is made longer by the idle increase correction means 10 as the engine temperature becomes lower, the increase ratio of the increase at the time of starting or the increase ratio of the increase after starting immediately after a complete explosion is This prevents the air-fuel ratio from becoming overrich due to the increase in idle amount being added at a steep rising slope when the engine temperature is low, and the engine always transitions smoothly from starting to idling, regardless of whether the engine temperature is high or low. .

(Example) Examples of the present invention will be described below.

As shown in FIG. 2, the intake passage 12 of the engine 11 is equipped with an air flow meter 14, a throttle valve 15, and an injector 16 from the air cleaner 13 side at the upstream end. The upper and downstream sides of the engine 15 are communicated by a bypass passage 17, and the bypass passage 17 is provided with a warm-up air valve 18 that opens when the engine 11 is cold started to increase the amount of intake air. Additionally, a fuel pump 20 is connected to the injector 16 from the fuel tank 19.
and low pressure side and high pressure side fuel filters 21, 2
2 is connected to the fuel supply pipe 23 led through the injector 16 and the fuel tank 1.
A pressure regulator 25 is installed on the fuel return pipe 24 between the intake passage 12 and the fuel return pipe 24. By being operated by pressure, the fuel injection pressure of the injector 16 is adjusted in accordance with the intake negative pressure.

On the other hand, the amount of fuel injected from the injector 16 into the intake passage 12 is controlled by a control signal a from a control circuit 40.
As shown in FIG. 3, this control circuit 40 includes a basic injection amount setting circuit 41, an air-fuel ratio correction circuit 42,
It is comprised of a starting amount increase setting circuit 43, a post-starting amount increasing setting circuit 44, an idle amount increasing setting circuit 45, and an idle amount increasing correction circuit 46. and,
As shown in FIGS. 2 and 3, the intake air amount signal b from the air flow meter 14 and the engine rotation speed signal c from the ignition coil 27
and the complete explosion signal d output when the ignition switch 28 is turned OFF are input to the basic injection amount setting circuit 41, and the O ₂
The air-fuel ratio signal e from the sensor 30 is input to the air-fuel ratio correction circuit 42, and the engine speed signal c and
The engine temperature signal f from the water temperature sensor 32 installed in the water jacket 31 and the cranking signal g output when the ignition switch 28 is turned on are connected to the starting fuel increase setting circuit 43.
The engine temperature signal f and the complete explosion signal d are input to the post-start increase setting circuit 44, which detects the complete explosion signal d, the engine rotational speed signal c, and the opening movement of the throttle valve 15. A throttle signal h from the throttle sensor 33 is input to an idle increase setting circuit 45.
Further, the output signal i of the idle increase setting circuit 45 and the engine temperature signal f are input to the idle increase correction circuit 46, and the output signal j of the idle increase correction circuit 46 and the above-mentioned post-start increase setting circuit 44 are input. The output signal k and the output signal l of the air-fuel ratio correction circuit 42 are input to the basic injection amount setting circuit 41. This basic injection amount setting circuit 4
1 and the output signal n of the start-up increase setting circuit 43 are input to a drive circuit 47, and the output signal of the drive circuit 47 is output to the injector 16 as the control signal a.

Next, the operation of the above embodiment will be explained.

First, when the ignition switch 28 is turned on to start the engine 11, the control circuit 40 turns on the ignition switch 28.
The starting increase setting circuit 43, which receives the cranking signal g from the engine 8 and the engine speed signal c from the ignition coil 27, determines that the engine has not fully exploded and that the engine speed is the cranking speed (e.g. 500 rpm), the cranking state of the engine is detected, and as shown in Fig. 4, the injection amount with the increase ratio P ₁ (>1.0) is set as the increase at startup, and the output signal n or control signal a is set. The signal is sent to the injector 16 as a signal. As a result, during cranking from t ₀ when the ignition switch 28 is turned on to t ₁ when the complete explosion occurs, the increased amount of fuel at startup is injected from the injector 16 into the intake passage 12 to promote ignition. Become. When the engine 11 completely explodes, the complete explosion signal d associated with the OFF operation of the ignition switch 28 is input to the basic injection amount setting circuit 41 of the control circuit 40, so that the circuit 41 outputs an intake air amount signal. The basic injection amount (increase ratio 1.0) is set by correcting the air-fuel ratio according to the intake air amount and engine speed indicated by b and engine speed signal c, and by the signal l from the air-fuel ratio correction circuit 42. . Also, engine 1
After the complete explosion in step 1, the post-start increase setting circuit 44 and the idle increase setting circuit 45 to which the complete explosion signal d is input set the post-start increase and the idle increase, respectively. In other words, the post-start increase setting circuit 44:
The portion exceeding the basic injection amount (increase ratio
P ₁ −1.0) is gradually decreased for a predetermined period of time T ₁ (=t ₂ −
Set the amount to increase after starting so that it reaches zero by multiplying by _t1 ). Therefore, the total injection amount of this post-start increase and the basic injection amount will be within the above specified time from the time of complete explosion _t1 .
During the period from T ₁ to time t ₂ , the amount is reduced from a value equal to the increase at startup to a value equal to only the basic injection amount. Further, the idle amount increase setting circuit 45 increases the idle amount by a predetermined increase value during the idle period T2 from the time _t1 when the complete combustion signal d is input to the time _t3 when the throttle signal h indicating the opening movement of the throttle valve ₁₅ is input. However, the rise of this idle increase from the complete explosion time t ₁ is the predetermined time after the start mentioned above when the increase becomes zero.
The amount is gradually increased from zero to the predetermined increase value over a set time _T3 , which is shorter than _T1 .
In other words, as shown in FIG. 5, the increase achievement rate of the idle power increase is increased from zero to 100% over the set time _T3 . Therefore, immediately after a complete explosion, there is no sudden increase in the increase ratio due to the sudden addition of the idle amount to the basic injection amount along with the increase after starting.
This will prevent the engine speed from dropping as shown in FIG. 7 due to this rapid increase.

By the way, the above explanation is for a case where the engine temperature is constant, but the starting fuel increase setting circuit 43 inputs the engine temperature signal f and increases the starting fuel increasing ratio P ₁ as the engine temperature is lower. Set it to do so. In other words, as shown in Fig. 4, when the engine is at high temperature, the increase in power at startup is set to a relatively small increase ratio _P1 , and when the engine is low, it is set to a large increase ratio _P1 '(> _P1 ) as shown by the chain line. be. In accordance with this, the after-start increase setting circuit 44 increases the increase in amount after starting by increasing the increase ratio over a predetermined time T ₁ ' longer than the predetermined time T ₁ at high temperature.
It is set to gradually decrease from P ₁ ′ to 1.0.
As a result, ignition during cranking is performed well even when the engine temperature is low, and the transition to the idling state after complete explosion is performed smoothly regardless of the engine temperature.

On the other hand, regarding the idle increase, the rising slope is set so that the increase rate becomes 100% over the set time T ₃ as described above, but if this slope is gentle, after the complete explosion When the engine temperature is high and the increase in power after starting becomes zero in a short time, the increase in idle power will be delayed to reach the specified increase value, and if the rising slope of this increase in idle power is steep, the increase in power at startup and the start immediately after complete detonation will be delayed. When the engine is at a low temperature, when the increase ratio _P1 ' of the post-increase is large, the idle increase is added relatively rapidly.
An overrich state similar to that which occurs when the weight increase achievement rate is instantaneously 100% immediately after a complete explosion will occur. However, the rising slope of this idle increase is corrected as follows by the idle increase correction circuit 46 to which the engine temperature signal f is input. That is, when the engine is at a low temperature, the set time T ₃ ' for increasing the idle amount from the time of complete explosion t ₁ to the predetermined increase value, as shown by the chain line in FIG. 4, is longer than the set time T ₃ when the engine is at a high temperature, as shown by the solid line. ,
The rising slope of the idle increase is set to be gentler as the engine temperature is lower. This is the fifth
Looking at the graph of the increase achievement rate in the figure, as shown by the chain line, the lower the engine temperature, the longer the time required to reach the 100% achievement rate is set. This prevents over-richness of the air-fuel ratio due to the steep addition of idle fuel immediately after complete combustion when the engine is at a low temperature, which increases the increase ratio of the starting fuel during cranking and the post-start fuel increasing immediately after complete combustion. condition is prevented, and engine vibration and engine stalling are prevented. In addition, when the engine temperature is high and the amount of increase after starting immediately after a complete explosion is small and the engine shifts to an idling state in a short time, the idle amount is increased to a predetermined amount increase value relatively quickly, and a delay in the idle amount increase is prevented. become.

Here, in FIGS. 4 and 5, the increase/decrease control of the starting fuel increase or the correction control of the rising slope of the idle fuel increase according to the engine temperature is shown for two cases: when the engine is high temperature and when the engine is low. The process is performed in multiple stages or steplessly depending on the engine temperature. Incidentally, FIG. 6 shows specific examples of each fuel increase characteristic for five cases of engine temperature of -20, 0, 20, 40, and 80°C.

(Effects of the invention) As described above, according to the invention, the fuel injection amount, which is set to a larger value as the engine temperature lowers during engine cranking, is increased at startup, and
In an electronically controlled fuel injection system that performs a post-start increase in which the increase at startup is reduced to the basic injection amount over a predetermined period of time after a complete explosion, and an increase in idle amount by a predetermined increase value, the idle increase is performed over a set time. Since the set time is adjusted according to the engine temperature, the air-fuel ratio can be temporarily overriched by adding the above-mentioned idle amount immediately after a complete explosion. The accompanying drop in engine speed and further engine stalling are effectively prevented regardless of the engine temperature, and good starting performance is always achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of the fuel injection device of the present invention, FIG. 2 is a control system diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing the configuration of a control circuit in the embodiment. 4 and 5 are graphs showing the control characteristics of the increase ratio and increase achievement rate according to the embodiment, FIG. 6 is a graph showing another control example of the increase ratio, and FIGS. 7 1 to 4 are graphs showing the conventional control characteristics and their This is a graph showing problems. 3...Basic injection amount setting means (41...basic injection amount setting circuit), 5...Starting increase setting means (43
. . . Start-up increase setting circuit), 7 . . . Post-start increase setting means (44 . . . Post-start increase setting circuit), 9 . . .
Idle amount increase setting means (45... Idle amount increase setting circuit), 10... Idle amount increase correction means (46
...idle increase correction circuit).

Claims (1)

[Scope of utility model registration request] basic injection amount setting means for setting a basic injection amount of fuel from the intake air amount and engine rotational speed; and starting increasing amount setting means for setting the injection amount to a larger value as the engine temperature decreases during engine cranking;
post-start increase setting means for gradually decreasing the injection amount set by the above-mentioned start-up increase setting means over a predetermined period of time from the time of complete explosion of the engine; an idle increase setting means for gradually increasing an increase value from zero to a predetermined increase value over a predetermined amount of time, and setting the increase value to the predetermined increase value after a set time elapses; 1. An electronically controlled fuel injection device comprising: an idle increase correction means for lengthening the idle increase rate to make the rising slope of the idle increase gentle.