JPS63263231A - Fuel controller of engine - Google Patents

Abstract

PURPOSE:To prevent the hunting of revolution speed and improve the re- startability of an engine by setting two revolution numbers to have the greater difference, which is used as the criterion in making the change and the selection between the start control mode or the regular run control mode, when the engine is hotter than that when the engine is cold. CONSTITUTION:The starter signal from a starter motor 18 and the signal from a water temperature sensor 12 are sent to a controller 9 and the start control mode in which starting fuel is supplied to the fuel injection valve 5 of each of cylinders or the regular running mode in which fuel is supplied to said valve 5 at the regular rate is selected according to the current engine r.p.m. Two selection determining points of engine r.p.m are set in both the revolution speed increasing range and the revolution speed decreasing range and have the hysteresis characteristics. And the difference between those two r.p.m points when the engine temperature is low is greater than that when the engine temperature is high. Then the startability with the cold engine is started may be improved and the startability after an engine stall with the hot engine is started also is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine fuel control device that takes into consideration engine startability in cold and warm conditions.

[Conventional technology]

Conventional fuel control devices for engines include
In this type of device, such as the "fuel injection device" shown in Publication No. 9830, normally, when the engine speed at startup is less than a preset start-up determination speed, the fuel injection device is injected into each cylinder each time each cylinder is ignited. At the same time, fuel is supplied at every ignition injection to facilitate starting, and when the engine speed is higher than the start-up determination speed, group injection is performed in the normal operating state to supply fuel to each group of cylinders. There is.

Then, on the upper limit side of the engine rotation speed, which is the side where every ignition injection is switched to group injection, the above-mentioned starting judgment rotation speed is determined by the temperature of the engine cooling water related to the engine temperature, as shown by curve E in FIG. is measured by a water temperature sensor and set appropriately according to the water temperature. On the other hand, when the engine speed decreases, which is the side when switching from group injection to every-ignition injection, the cooling water temperature changes as shown in curve F. Regardless,
It is set based on so-called hysteresis by subtracting a certain value from the startup determination rotation speed on the rising side.

[Problem that the invention seeks to solve]

However, during a cold start, the viscosity of the engine oil is high, so the engine speed starts up slowly and the engine speed drops quickly. Therefore, it is necessary to increase the starting determination rotation speed on the side where every ignition injection is switched to group injection, that is, on the side where the engine rotation speed increases. This is to minimize the sluggish state that occurs when transitioning from every-ignition injection to group injection.On the other hand, during engine starting, that is, during cranking, the engine speed decreases due to the above reasons. In this case, if the upper limit set value of the starting judgment rotation speed for switching from every ignition injection to group injection is close to the lower limit side setting value of the starting judgment rotation speed for switching from group injection to every ignition injection, then every ignition Hunting occurs when injection and group injection are repeated, resulting in improper fuel injection and deterioration of starting performance.For this reason, the difference in starting rotation speed between the ascending side and descending side is increased. However, as mentioned above, if the starting judgment speed on the falling side of the engine speed is set with hysteresis with respect to that on the upper limit side, the engine speed will change during warm starting. If the starting judgment rotation speed on the upper limit side is set to a low value,
As described above, since the hysteresis is set large in consideration of the cold start, the start determination rotation speed on the lower side of the engine rotation speed is calculated to be below Qrpm.

For example, as shown in Fig. 10, the engine rotation speed for increasing the engine speed is set to 11000 rpm for a cold start and 500 rpm for a warm start, while the hysteresis is set to 70 Orpm and the engine speed decreases. If the starting determination rotation speed is set on the side, the value at warm starting will be -20° rpm in calculation. For this reason, when restarting the engine after it has stalled, the engine speed does not fall below the start-up determination speed (-20 rpm) on the descending side, so group injection is performed suddenly, ensuring startability. The problem is that it cannot be done.

[Means for solving problems]

In order to solve the above-mentioned problems, the engine fuel control device of the present invention detects a starting state in which the engine rotation speed is equal to or lower than the starting determination rotation speed by the starting state detection means, and when the starter is turned on. , while the starting control means supplies starting fuel to the fuel injection valve, when the starting state detecting means detects a normal operating state in which the engine rotation speed is equal to or higher than the starting determination rotation speed □, the normal operation control means At the same time, the above-mentioned starting state detection means performs an operation of supplying normal operating fuel to the fuel injection valve, and detects the starting judgment rotation speed on the side where the engine rotation speed increases, which is the judgment rotation speed when switching from the starting state to the normal operation state. and a first starting state detection means that has a value lower than the start judgment rotation speed on the increasing side of the engine rotation speed.
a second starting state detection means that sets a starting judgment rotation speed on the lower side of the engine rotation speed, which is the judgment rotation speed when switching from the normal operating state to the starting state; In an engine fuel control device where the engine speed is set to a higher value on the low-temperature side than on the high-temperature side, the engine speed is set to be higher on the low-temperature side than on the high-temperature side. The configuration is such that the difference is set larger on the low temperature side than on the high temperature side.

[For production]

As mentioned above, the difference between the starting judgment rotation speed on the side where the engine speed increases and the starting judgment speed on the side where the engine speed decreases is set to be larger on the low temperature side than on the high temperature side, resulting in rotation failure. On the stable low-temperature side, hunting of the engine speed that goes up and down between the above-mentioned restart judgment speeds does not occur, and on the high-temperature side, when the engine stalls, the engine speed can be calculated with certainty. The engine rotation speed can be lowered to below the start determination rotation speed on the lower side, and startability is ensured.

[Embodiment 1] A first embodiment of the present invention will be described below based on FIGS. 1 to 4.

At the top of the engine, as shown in Fig. 1, a cylinder head 1 is provided with a spark plug 3 for igniting fuel, and this cylinder head 1 has an intake pipe 4 on the intake side. is connected. In the intake pipe line 4, in order from a position close to the cylinder head 1, an injector 5, which is a fuel injection valve that injects fuel by receiving an injection pulse sent from a control unit 9, and an intake valve that measures the temperature of intake air. An air temperature sensor 6, a throttle valve 7 that controls intake air IQ in response to accelerator operation, and an air flow meter 8 that measures intake air IQ are provided. These injector 5, intake air temperature sensor 6, throttle valve 7, and air flow make 8 are connected to a control unit 9.

A cooling water passage 11 is formed in the cylinder block 10 connected to the lower end of the cylinder head 1, and a water temperature sensor 12 is installed in the cooling water passage 11 to measure the temperature of the engine cooling water related to the engine temperature. It is provided. In addition, the spark plug 3 is supplied with high pressure, and a crank position detection signal NE and a cylinder discrimination signal G are sent to the control unit 9 to determine the engine rotation speed N, fuel injection timing, etc. A supply distributor 2 is connected. The distributor 2 generates high pressure by receiving the ignition signal IGt from the control unit 9.
An igniter 13 is connected to send an ignition confirmation signal IGf to. The water temperature sensor 12, distributor 2, and igniter 13 are connected to the control unit 9.

Furthermore, inside the engine, there is a piston at the upper end.
4 is attached to a crankshaft (not shown), and a starter motor 1B is connected to this crankshaft via a flywheel 16 and a small gear 17. The starter motor 18 has
Battery 20 via ignition key switch 19
is connected, and the control unit 9 is connected,
A starter signal generated when the starter motor 18 rotates is supplied to the control unit 9.

The control unit 9 described above includes the following means. That is, the engine cooling water temperature table has an engine cooling water temperature table that sets a starting judgment rotation speed N5TU on the side where the engine rotation speed increases, which is the judgment rotation speed when switching from the starting state to the normal operating state, in accordance with the engine cooling water temperature. When the engine rotation speed N becomes the start judgment rotation speed N5TD in the state detection means and a starter signal is received, it is known from the start judgment rotation speed N5TU corresponding to the engine cooling water temperature and the crank position detection signal NE of the distributor 2 output. It has a first starting state detection means for comparing the engine rotational speed N, and an engine cooling water temperature table in which a starting injection pulse width TS for determining the fuel supply time is set corresponding to the engine cooling water temperature, and the first starting state When the detection means reaches the engine rotation speed N (starting determination rotation speed N5TU), in response to the ignition signal IGt sent to the igniter 13, the injector 5 injects fuel with a starting injection pulse width TS corresponding to the engine cooling water temperature. It calculates the basic fuel injection time from the engine rotation speed N and the intake air amount Q of the air flow meter 8 output, and also calculates the basic fuel injection time from the intake air temperature sensor 6 output, water temperature sensor 12 output, and throttle valve 7.
The final injection time TI is calculated by correcting the basic injection time based on the increase rate based on the opening degree, etc., and the first starting state detection means determines that the engine rotation speed N>starting judgment rotation speed N5TU
, when the second starting state detection means determines that the engine rotational speed N>starting judgment rotational speed N5TD and the starter signal is OFF, and the second starting state detection means determines that the engine rotational speed N>starting judgment rotational speed N5TD. normal operation control means that receives the ignition signal IQt and causes the injector 5 to perform fuel injection according to the final injection time TI, and determines when to switch from the normal operation state to the starting state in accordance with the engine cooling water temperature. It has an engine cooling water temperature table in which a starting judgment rotational speed N5TD is set on the lowering side of the engine rotational speed, which is the engine rotational speed, and the above-mentioned starting judgment rotational speed N5TD and engine rotational speed N corresponding to the engine cooling water temperature in a normal operating state are set. and second starting state detection means for comparison.

The starting determination rotation speed N5TU set in the first starting state detection means is set to a sufficiently high value on the cold side in consideration of startability, as shown in the curve in Figure 2, and on the warm side. The value on the cold side is lower than that on the cold side. Further, as shown in curve B of the figure, the start determination rotation speed N5TD on the engine rotation speed decreasing side set in the second starting state detection means is equal to the start determination rotation speed N5TD on the engine rotation speed increase side of curve A. T U
The difference between the two values is large on the cold side and small on the warm side.

In the above configuration, the operation of the fuel control device of this engine will be explained based on the flowchart shown in FIG.

First, when the ignition key switch 19 is turned on to connect the battery 20 and the starter motor 18, the starter motor 18 rotates and the driving force of the starter motor 18 is transmitted to the crankshaft via the pinion 17 and the flywheel 16. The piston 14, ie, the engine, rotates. At this time, a starter signal is simultaneously sent from the starter motor 18 to the control unit 9 (Sl). Here, if the starter signal is in the OFF state, that is, if the engine is in operation, the process moves to step S9, which is the first stage of the routine for injecting fuel based on calculations in the normal operating state. Next, by receiving the starter signal, the control unit 9 detects the temperature T of the engine coolant through the water temperature sensor 12.
Read the HW (S2) and set the preset THW.
From the table, a starting determination rotation speed N5TU on the increasing side of the engine rotation speed is determined (S3). Next, the engine rotation speed N is read using the crank position detection signal NE sent from the distributor 2 (S4), and compared with the start determination rotation speed N5TU (S5). Then, if engine rotation speed N>starting determination rotation speed N5TU, the process moves to step S9. Further, if the engine rotational speed N is the starting determination rotational speed NSTU, the starting injection pulse width TS, that is, the fixed injection amount of fuel according to the water temperature is determined from a preset THW table (S6). Then, it is determined whether the ignition signal IGt has been input (S7), and if the ignition signal IGt has been input, injection with the starting injection pulse width TS is executed to each cylinder (S8). The above routine injects a fixed amount of fuel without calculation, and is repeated when the starter signal is ON and the engine rotational speed N is equal to the start determination rotational speed N5TU.

After that, when the starter signal is OFF or the engine rotation speed N>starting judgment rotation speed N5TU, the engine rotation speed N and intake air IQ are read (S9).
, From the formula Tp=KXQ+N, the basic fuel injection time'
Find rp (SIO). Next, various signals are read, such as reading the water temperature from the water temperature sensor 12, reading the throttle opening from the throttle valve 7, and reading the intake air temperature from the intake air temperature sensor 6 (Sll).

Then, by performing calculations such as multiplying the fuel increase rate obtained by reading each of these signals by the basic injection time 'r p, for example, if the water temperature is low, the fuel injection increase the amount of fuel, change the fuel increase rate depending on whether it is idling or non-idling, or increase the amount of fuel injected when the intake air temperature is low because the air density is high, and vice versa. Since the air density is low when the air temperature is high, the final injection time TI is determined by making corrections such as reducing the fuel injection amount (S12). Next, it is determined whether the number of readings of the crank angle signal NIE has reached a predetermined value (513), and if it has reached the predetermined value, fuel injection is performed to the corresponding cylinder of the engine according to the final injection time TI (S14).
).

After that, the engine coolant temperature is read (S1
5) The engine rotation speed N5TD on the lowering side of the engine rotation speed is determined from the T HW table (S16), and the engine rotation speed N is compared with the engine rotation speed N5TD for start determination (3.17). Then, if the engine rotation speed N>starting judgment rotation speed N5TD, the process moves to step S9 and repeats the fuel injection routine based on the calculation of the normal operating state, while on the other hand, the engine rotation speed N is the starting judgment rotation speed N5T.
If D, the process moves to step S1 to check the presence or absence of the starter signal. If the scooter signal is OFF, the process moves to step S9, and if the starter signal is ON, the routine from step 82 onwards is repeated.

In the above control, as shown in FIG. 4, for example, the engine rotation speed upper limit side starting determination rotation speed N5TU to reach a certain temperature on the cold side is set to 85 Or pm, and the engine rotation speed lowering side is set to 85 Or pm. The starting judgment rotation speed N5TD at a certain temperature on the warm side is 28 Orpm, and the starting judgment rotation speed N5TU at a certain temperature on the warm side.
is 50Orpm, and the starting judgment rotation speed N5TD is 22Orpm.
m, it is possible to obtain a sufficient difference between the starting judgment rotation speed N5TU and the starting judgment rotation speed N5TD on the cold side, and the starting judgment rotation speed N5TD on the warm side is an appropriate value. , good control can be achieved.

[Example 2] A second example of the present invention is shown in FIGS. 2, 3, 5, and 6.
This will be explained below based on the figures.

In the engine fuel control device according to the present embodiment, the engine rotation speed decreasing side start determination rotation speed N in the second determination means
5TD is set to a constant value regardless of the engine cooling water temperature, as shown by straight line C in FIG. Therefore, in the flowchart of FIG. 3, step S15 between point a and point
-17 are combined with step S18 shown in FIG. 5. According to this configuration, as shown in FIG. (In both cold and warm starts, group injection is switched to every-ignition injection at 25 Or pm, and control is simple. It is possible to maintain a sufficiently large rotational speed difference with respect to the starting determination rotational speed N5TU on the engine rotational increasing side shown by curve A.

[Embodiment 3] A third embodiment of the present invention is shown in FIGS. 2, 3, 7, and 8.
This will be explained below based on the figures.

In the engine fuel control device according to the present embodiment, the engine rotation speed decreasing side start determination rotation speed N in the second determination means
5TD is the starting judgment rotation speed N5 on the rising side of the engine rotation speed.
It is obtained by subtracting the start determination hysteresis N5TH, which is set corresponding to the engine cooling water temperature', from TU. This start determination hysteresis N5TH is set to a high value on the cold side, and set to a low value on the warm side. Therefore, the obtained starting determination rotation speed N5TD is the second
As shown in the curve in the figure, on the cold side, the starting judgment rotation speed N
The difference with 5TU is large, and the difference is small on the warm side. In the flowchart of FIG. 3, steps S16 and 17 between the 0 point and the point are shown in step S1 of FIG.
It will be replaced with 9/20. According to this configuration,
As shown in FIG. 8, the starting judgment rotation speed N5TD is 850 when the starting judgment rotation speed N5TLI is at a certain temperature on the cold side.
rpm, 500 rpm at a certain temperature on the warm side,
Hysteresis on the cold side at each temperature: 600 rpm
, is the value obtained by subtracting the hysteresis of 250 rpm on the warm side, and as in the previous two examples, on the cold side,
It is possible to maintain a large rotational speed difference with respect to the starting determination rotational speed N5TU on the engine rotational increasing side, and also to maintain an appropriate value on the warm side.

〔Effect of the invention〕

As described above, in the engine fuel control device of the present invention, when the starting state detecting means detects a starting state in which the engine rotation speed is equal to or less than the starting determination revolution speed, and the starter is ON, the engine fuel control device While supplying starting fuel to the fuel injection valve, when the starting state detecting means detects a normal operating state in which the engine rotation speed is equal to or higher than the starting determination rotation speed, the normal operation control means starts supplying starting fuel to the fuel injection valve. At the same time, the starting state detecting means performs the operation of supplying normal operating fuel to the engine, and the starting state detecting means also detects a first engine which is set with a starting judgment rotation speed on the side where the engine rotation speed increases, which is the judgment rotation speed when switching from the starting state to the normal operating state. A starting state detection means and a starting judgment rotational speed on the side where the engine rotational speed is decreasing are set, which is a judgment rotational speed when switching from the normal operating state to the starting condition, which is a value lower than the starting judgment rotational speed on the side where the engine rotational speed is increasing. a second starting state detection means, and the starting determination rotation speed set by at least the first starting state detection means is set to a higher value on the low temperature side than on the high temperature side, The difference between the start determination rotation speed on the side where the engine rotation speed increases and the start determination rotation speed on the engine rotation speed decrease side is set to be larger on the low temperature side than on the high temperature side. Therefore, in a cold state, it is possible to make a large difference between the starting judgment speed on the side of increasing engine speed and the starting judging speed on the side of decreasing engine speed, so that each ignition injection and group This is because it is possible to prevent hunting that impairs the stability of engine rotation, such as when injection and injection are performed alternately, and to maintain the starting judgment rotation speed on the downward side of engine rotation speed at an appropriate value when the engine is warm. , it is possible to ensure restarting of the engine after stalling during warm conditions.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is an overall configuration diagram of a fuel control device for an engine, and FIG. 2 is a fuel control device for an engine shown in FIG. FIG. 3 is a flowchart showing the operation of the fuel control device of the engine shown in FIG. 1. , FIG. 4 is an explanatory diagram showing the relationship between the start determination rotation speed N5TU and the start determination rotation speed N5TD at the time of cold start and warm start, and FIG. A flowchart of the main parts showing the operation of the fuel control device, FIG. 6 shows the start judgment rotation speed N5TU and the start judgment rotation speed at cold start and warm start according to the fuel control device of the engine shown in FIG. N5TD
FIG. 7 is a flowchart showing the main part of the operation of the engine fuel control device according to another embodiment of the present invention, and FIG. 8 is the engine fuel control device shown in FIG. 7. FIG. 9 is an explanatory diagram showing the relationship between the start determination rotation speed N5TU and the start determination rotation speed N5TD during a cold start and a warm start according to FIG. Starting judgment rotation speed N5T
A graph showing U and the start determination rotation speed N5TD on the lower side of the engine rotation speed, FIG. Starting judgment rotation speed N5TU and starting judgment rotation speed N5T
It is an explanatory diagram showing the relationship with D. 2 is a distributor, 5 is an injector (fuel injection valve), 6 is an intake air temperature sensor, 7 is a throttle valve,
8 is air flow meter, 9 is control '+111 unit, 1
2 is a water temperature sensor, 13 is an igniter, 18 is a starter motor, and 19 is an ignition key switch.

Claims (1)

[Claims] 1. When the starting state detecting means detects a starting state in which the engine rotational speed is equal to or less than the starting determination rotational speed and the starter is ON, the starting control means supplies starting fuel to the fuel injection valve, and the above starting state is detected. When the detection means detects a normal operating state in which the engine rotation speed is equal to or higher than the starting determination rotation speed, the normal operation control means performs an operation of supplying normal operating fuel to the fuel injection valve, and at the same time The detection means includes a first starting state detection means that sets a starting judgment rotational speed on the side where the engine rotational speed increases, which is a judgment rotational speed when switching from the starting state to the normal operation state, and a starting judgment rotational speed on the side where the engine rotational speed increases. a second starting state detection means that sets a starting judgment rotation speed on the lower side of the engine rotational speed, which is a judgment rotational speed when switching from the normal operating state to the starting state, which is a lower value than the first starting state. In an engine fuel control device in which the start judgment rotation speed set by the state detection means is set to a higher value on the low temperature side than on the high temperature side, the start judgment rotation speed on the side where the engine rotation speed increases and the engine rotation speed decrease are determined. 1. A fuel control device for an engine, wherein the difference between the rotation speed and the starting determination rotation speed on the low temperature side is set to be larger than on the high temperature side.