JPS60153442A - Fuel feed device for engine - Google Patents

Abstract

PURPOSE:To prevent an air-fuel mixture from coming into being overlean, by limiting a degree of suction temperature compensation at a time when output of a suction temperature sensor detects a specified operating region which shows a higher value than that in the actual suction temperature. CONSTITUTION:When a suction temperature compensation circuit 17 is added with an on-signal out of an ignition switch 9 and judges a warm starting period from each A/D converter output out of an engine speed sensor 10 and a water temperature sensor 7, it sets a setting value T to a timer. And, the A/D converter output of a suction temperature sensor 8 is stored in a register, while it is substracted from the setting value T, and suction temperature is multiplied by a compensation factor K, for example, 0.8 whereby it is slightly compensated. This compensated suction temperature Ta is outputted therefrom, and pulse width of a fundamental fuel injection pulse out of a map 14 is compensated at an opertion circuit 20 by way of a D/A converter 18 and a function generator circuit 19. Next, when the timer setting value T comes to nil, the suction temperature prior to compensation is outputted as it is. With this constitution, an air-fuel mixture is obviated so that an output drop and an engine stall are preventable from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply device for an engine.

[Prior art]

Generally, a fuel supply device for an engine attempts to efficiently operate the engine by supplying an amount of fuel to the engine according to the amount of intake air. For example, in an engine's carburetor, the amount of fuel introduced is controlled by the venturi negative pressure in the intake passage, and in an engine's fuel injection device, the amount of intake air is detected by an air flow sensor, and the amount of intake air is controlled according to the output of the sensor. The fuel injection amount is controlled. However, in this case, if the fuel supply amount is controlled simply by the venturi negative pressure or according to the output of the airflow sensor, the venturi negative pressure changes with the intake flow rate as a parameter, and the airflow sensor normally , Karman vortex type to detect the volumetric flow rate of intake air.

Since speed density type and Hoehn type sensors are used, a problem arises in that the air-fuel ratio of the mixture deviates from the set value when the intake air temperature changes and the intake air density changes.

In order to solve this problem, conventionally, an intake air temperature sensor is installed in the middle of the intake passage, and the fuel supply amount is corrected and controlled based on the sensor's output. There is one shown in Japanese Patent Application Laid-Open No. 57-51299. However, with conventional fuel supply systems that perform such intake temperature correction, engine output may decrease during warm starting or acceleration, etc.
Engine stalls sometimes occurred.

As a result of intensive research aimed at preventing engine output reduction and engine stalling, the inventor of the present invention discovered that the following causes the output reduction and engine stalling. That is, FIG. 1 shows temporal changes in the intake air temperature a in the intake passage, the output of the intake air temperature sensor, the engine cooling water temperature C, and the outside air temperature d. According to Fig. 1, when the engine is cold-started, the intake air temperature sensor detects the intake air temperature (see the dashed line a in the figure) without delay, as shown by the solid line in the figure, and on the other hand, the engine cooling water As shown by solid line C in the figure, the temperature rises immediately after the engine starts and reaches approximately 80°C.
remains almost constant. Once the engine is stopped, the cooling water temperature C gradually decreases from about 80°C, but at that time, the intake air in the intake passage is heated by this high temperature engine cooling water, and the intake air temperature a is about 30°C. The intake temperature sensor itself, which is in contact with this high-temperature intake air, also rises in temperature. When the engine is started, that is, warm-started, in this condition, low-temperature outside air is drawn into the intake passage as shown by the broken line d in the figure, and the intake air temperature a immediately decreases to its original temperature of about 30°C. However, as mentioned above, since the intake air temperature sensor itself is hot when the engine is stopped,
A detection delay occurs in the sensor, and the sensor generates an output corresponding to a temperature higher than the actual intake air temperature a. Therefore, when the intake temperature of the fuel supply amount is corrected based on the output of this intake temperature sensor, the correction control becomes over-controlled and the fuel supply amount decreases, which causes the air-fuel ratio of the air-fuel mixture to become over-lean and the engine output. The engine may slow down or stall. That is, a sudden increase in the amount of intake air and a delay in detection by the intake air temperature sensor at that time cause a decrease in engine output and engine stalling.

(Object of the Invention) In view of the above-mentioned problems, it is an object of the present invention to provide an engine fuel supply device that can prevent a decrease in engine output and the occurrence of engine stalling.

[Structure of the invention]

Therefore, the present invention provides an engine fuel supply system in which an intake salt sensor is disposed in the intake passage of the engine, and the intake air temperature is corrected for the fuel supply amount based on the output of the sensor. A specific operating range in which the intake air temperature is higher than the intake air temperature is detected, and the above-mentioned intake air temperature correction is limited in the specific operating range, thereby preventing the air-fuel ratio of the air-fuel mixture from becoming over-lean.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2 and 3 show an engine fuel supply system according to an embodiment of the present invention, and this is an example applied to an engine fuel injection system. In the figure, 1 is an engine, 2 is an intake passage of the engine 1, 2a is an intake air heating part formed in the middle of the intake passage 2 and heats intake air, 3 is a fuel injection valve disposed in the middle of the intake passage 2, 4 is a throttle valve, 5 is an air cleaner, 6 is a negative pressure sensor which is a speed density type air flow sensor arranged downstream of the throttle in the intake passage 2, 7 is a water temperature sensor that detects the engine cooling water temperature, 8 is an intake air An intake air temperature sensor is disposed near the engine 1 in the passage 2 and detects the intake air temperature; 9 is an ignition switch; 10 is a rotational speed sensor; 12 is a sensor that controls the fuel injection amount in response to the outputs of the above-mentioned sensors 6 to 10; This is a control circuit that performs

Further, FIG. 3 shows a more detailed configuration of the control circuit 12. In the figure, the same reference numerals as in FIG. 2 indicate the same parts as in the same figure, 13 is an A/D converter that A/D converts the re-outputs of the rotation speed sensor 10 and the negative pressure sensor 6, and 14 is the engine rotation speed. A basic fuel injection pulse generation circuit that has a pulse width map of basic fuel injection pulses with and negative pressure as parameters, and generates a basic fuel injection pulse width according to the A/D conversion outputs of both the sensors 6.10. , 15 connects the output of the circuit 14 to D/
This is a D/A converter that performs A conversion.

Further, 16 is an A/D converter that converts each output of the water temperature sensor 7, intake temperature sensor 8, and rotation speed sensor 10 into A/D, and 17
receives the A/D conversion output of the above-mentioned sensors 7, 8, and 10 and the output of the ignition switch 9, and normally outputs the A/D conversion output of the intake air temperature sensor 8 as is.On the other hand, when starting when the water temperature is higher than the set value That is, at the time of a warm start, the A/D conversion output of the air temperature sensor 8 is discounted for a fixed time after the start, and the output is corrected to a small value. 18 is an intake temperature correction circuit I7. A D/A converter 19 converts the output from the D/A converter into a D/A converter, and outputs a correction coefficient that becomes smaller as the intake air temperature increases, as shown in FIG. 4, in accordance with the D/A converted intake air temperature sensor output. function generation circuit,
20 is an arithmetic circuit that multiplies and corrects the D/A-converted basic fuel injection pulse width by the output of the function generating circuit 19; 21 is an injection valve drive that drives the fuel injection valve 3 according to the output of the arithmetic circuit 20; It is a circuit.

In the above configuration, the basic fuel injection pulse generation circuit 14 serves as a fuel supply amount adjustment device that adjusts the amount of fuel supplied to the engine, and the function generation circuit 19 and calculation circuit 20 function as an intake temperature sensor. The correction means corrects and controls the fuel supply amount adjusting device so that the fuel supply amount decreases as the intake temperature increases based on the output of the intake air temperature sensor. The intake air temperature correction circuit 17 serves as a specific operating state detection means for detecting an operating state in which the temperature becomes higher than the actual intake air temperature, and further includes a limiting means for limiting the above-mentioned correction control in response to the detection output of the specific operating state detection means. It becomes.

Next, the general operation of this device will be explained using FIG. 3.

When the engine is cranked, the negative pressure sensor 6 detects the intake negative pressure downstream of the throttle valve 4, the water temperature sensor 7 detects the engine cooling water temperature, and the intake air temperature sensor 8 detects the temperature of the intake air when it is heated and taken into the engine. The intake air temperature is detected by the rotational speed sensor 10, and the engine rotational speed is detected by the rotational speed sensor 10, and the outputs of the negative pressure sensor 6 and the rotational speed sensor 100 are A/D converted by the A/D converter 13.
After being converted, it is input to the basic fuel injection pulse generation circuit 14. Then, this basic fuel injection pulse generation circuit 14 determines the pulse width of the basic fuel injection pulse according to the engine speed and intake negative pressure, and converts it into a D/A converter 15.
After conversion, it is input to the arithmetic circuit 20. On the other hand, the respective outputs of the water temperature sensor 7, intake temperature sensor 8, and rotation speed sensor 0 are A/D converted by an A/D converter 16 and then applied to an intake temperature correction circuit 17. When an ignition signal is input from the ignition switch 9, the intake air temperature correction circuit 17 determines whether or not it is a warm start time based on the engine cooling water temperature.

If it is not a warm start, the intake temperature correction circuit 17
outputs the A/D conversion output of the intake temperature sensor 8 as it is, performs D/A conversion with the D/A converter 18, and then inputs it to the function generation circuit 19, which circuit 19 responds to the output of the intake temperature sensor. The calculation circuit 20 calculates the correction coefficient (see Fig. 4).
Add to.

Then, this arithmetic circuit 20 corrects the pulse width of the basic fuel injection pulse using the correction coefficient and applies a fuel injection pulse with the corrected pulse width to the fuel injection valve 3, thereby adjusting the fuel injection amount. is corrected and controlled to a smaller amount as the intake temperature rises in accordance with the output of the intake temperature sensor.

On the other hand, during a warm start, the intake temperature correction circuit 17 corrects the A/D conversion output of the intake temperature sensor 8 to a small value during a fixed period of time after start, and the function generating circuit 19 As a result, the fuel injection amount becomes larger compared to the case when the engine is not at warm start time even for the same output from the intake air temperature sensor 8. In this way, during a warm start, the correction control of the fuel injection amount is limited for a fixed period of time after the start.

Next, using the flowchart in FIG. 5, the intake air temperature correction circuit 1
7 will be explained in detail.

When the ignition signal from the ignition switch 9 is applied to the intake temperature correction circuit 17, the intake temperature correction circuit 17 first reads the A/D conversion output N of the rotation speed sensor 10 and adjusts it to the set value, for example 500 rpm. From the above determination, it is determined whether or not the engine has started (step 30), and the process waits in step 30 described above until the engine starts, and when the engine starts, it is determined YES in step 30, and step 3
1, the A/D conversion output of the water temperature sensor 7 is read and stored in the register Th, and it is determined whether or not the engine cooling water temperature Tw is equal to or higher than the set value C to determine whether or not it is time to warm start the engine. (step 32).

When the engine is warmly started, the intake temperature correction circuit 17
If YES is determined in step 32 above, step 33 is executed.
Then, set the set value T to the timer, then read the A/D conversion output of the intake salt sensor 8 and store it in the register Ta (step 34), and then set the timer value T.
is 0 (step 35), subtracts 1 from the timer value T (step 36), and multiplies the read intake air temperature Ta by a correction coefficient K, for example 0.8, to obtain the intake air temperature Ta. After correcting to a small value (step 37
), the corrected intake air temperature Ta is outputted as 1 (step 38), the process returns to step 34, and the route from steps 34 to 38 is repeated. and timer 41
When u becomes O, a YES determination is made in step 35, and the process directly proceeds to step 38, where the intake air temperature Ta read in step 34 is output as is.

If the engine is not at warm start, the intake air temperature correction circuit 17 makes a negative determination in step 7 32 and proceeds through steps 34, 35, and 38, and in this case as well, the intake air temperature Outputs the temperature Ta as is.

In the device of this embodiment as described above, the output of the intake air temperature sensor is corrected to a small value at the time of warm start, and the intake air temperature correction of the fuel injection amount is performed based on the corrected intake air temperature sensor output. Since the intake air temperature correction is discounted, the fuel injection amount correction control will not become overcontrolled and the injection amount will become smaller, and as a result, the air-fuel ratio of the air-fuel mixture will be prevented from becoming over-lean. This can prevent a decrease in engine output and the occurrence of engine stalling.

2 By the way, in the above embodiment, when the engine is started with a high coolant temperature (warm start), the intake temperature correction of the fuel injection amount is limited, but one of the causes of the mixture becoming over-lean is that Since the amount of intake air increases rapidly and the intake air temperature changes rapidly, the present invention is designed to adjust the intake air temperature of the fuel injection amount when there is a large difference between the intake air temperature when the engine is stopped and the intake air temperature when the engine is started. Correction may be limited.

FIG. 6 shows the calculation process of the intake temperature correction circuit 17 in another embodiment of the present invention, which limits the intake temperature correction of the fuel injection amount when the difference in intake air temperature between when the engine is stopped and when the engine is started is large. The flow is shown below.

Next, using FIG. 6, the intake temperature correction circuit 17 in this device
The arithmetic processing operation will be explained. When the ignition signal is applied to the intake temperature correction circuit 17, the intake temperature correction circuit 17
First, it is determined whether the engine has started or not (step 30), and when the engine has started, the step 30T: Y
It is determined as ES and the process proceeds to step 39, where the intake air temperature sensor output is read and stored in register Ta, and then the value of register Ta is stored in register Tam.
0), the intake air temperature sensor output Ta at the time of engine starting, which is the value of the register Ta, and the static memory Tm, which will be described later.
It is determined whether the difference Ta-Tm from the intake air temperature sensor output Tm when the engine is stopped, which is the value of , is greater than or equal to a set value C1 (step 41).

If the difference Ta-Tm between the intake temperature sensor outputs between when the engine is started and when the engine is stopped is equal to or greater than the set value 01, the intake temperature correction circuit 17 determines YES in step 41 and proceeds to step 42. Therefore, the intake temperature sensor output is newly read and stored in register Ta, and this register T
It is determined whether the difference between the aO value and the value of the register Tam is greater than the set value C2 (step 43), and the difference between the two (
Tam-Ta) is larger than the set value C2, an output change occurs in the intake air temperature sensor 8, and a detection delay occurs.
Then, from the stored contents of both registers Ta and Tan, an appropriate intake temperature sensor output value Ta (=f (Ta
, Tam)), and then updates the value of register Tam0 with the value of register Ta (step 46), and outputs the output value Ta of the intake air temperature sensor determined above (step 47). Here, the appropriate output value Ta of the intake temperature sensor is determined, for example, from the difference (Ta-Tam) between the stored contents of both registers Ta and Tam using the characteristics shown in FIG. The intake air temperature sensor output may be corrected by

In addition, if the difference between the value of register Ta and the intake temperature sensor output Tm when the engine is stopped is smaller than the set value C1, and if the difference between the values of registers Ta and Tam is smaller than the set value C2, the intake temperature sensor 8 detects Since no delay has occurred, the intake temperature correction circuit 17 makes a negative determination in step 41 or 43, proceeds to step 45, and proceeds to step 39.
Alternatively, the intake air temperature sensor output read in step 42 is stored in the static memory Tm, and the process proceeds through the path of step 46.38 to directly output the intake air temperature sensor output stored in the register Ta.

Note that in the above two embodiments, the specific operating conditions in which the intake air temperature 5 correction of the fuel injection amount should be limited are detected as the starting time when the engine cooling water temperature is high, or the starting time when the difference in intake air temperature between when the engine is stopped and when the engine is stopped is large. However, this specific operating state is only during startup.

Alternatively, the time of acceleration may be detected, and in any case, an operating state in which the intake air temperature corresponding to the output of the intake air temperature sensor becomes higher than the actual intake air temperature may be detected. In addition, if the intake temperature correction limit can prevent the mixture from becoming overlean,
The method may be different from that in the above embodiment.

Further, in the above embodiment, a fuel injection device for an engine has been described, but the present invention can of course be similarly applied to a carburetor for an engine. Further, the air flow sensor may be of a Karman vortex type or a vane type instead of a speed density type.

〔Effect of the invention〕

As described above, according to the present invention, an intake temperature sensor is disposed in the intake passage of the engine, and the fuel supply amount is corrected for the intake temperature based on the output of the sensor. A specific operating region in which the output of the temperature sensor shows a value higher than the actual intake air temperature is detected, and the above-mentioned intake temperature correction is limited in this specific operating region, so that the intake temperature correction of the fuel supply amount is not over-controlled. Therefore, the amount of fuel does not decrease, and as a result, the air-fuel mixture is prevented from becoming overly lean, which has the effect of preventing a decrease in engine output and the occurrence of engine stalling.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention, FIG. 2 is a schematic configuration diagram of an engine fuel supply system according to an embodiment of the present invention,
FIG. 3 is a detailed configuration diagram of the above device, FIG. 4 is a diagram showing the input/output characteristics of the function generation circuit 19 in the above device, and FIG. 5 is a flowchart of the arithmetic processing of the intake temperature correction circuit 17 in the above device. 6 is a diagram showing a flowchart of the arithmetic processing of the intake temperature correction circuit 17 in another embodiment of the present invention, and FIG. 7 is a diagram for explaining the operation of the intake temperature correction circuit 17. DESCRIPTION OF SYMBOLS 1... Engine, 7... Water temperature sensor (specific operating state 7 detection means), 8... Intake temperature sensor, 14... Basic fuel injection pulse generation means (fuel supply amount adjustment device), 17.
. . . Intake temperature correction circuit (limiting means), 19 . . . Function generation circuit (correction means), 20 . . . Arithmetic circuit (vIIi positive means). Patent applicant Ken Hayase, agent for Toyo Kogyo Co., Ltd. Patent attorney - 8-1 Procedural amendment to Figure 2 of Figure 7 (spontaneous) November 13, 1980 Patent application No. 59-9217 2, name of the invention Engine Fuel supply device 3, relationship with the amended person case Patent applicant May 15, 1980 Name changed (all at once) Address 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Name (313) Mazda Motor Corporation 4. Agent address: 532 4-1-45-5 Yodogawa-ku, Osaka City
, Column 6 of Detailed Description of the Invention of the Specification Subject to Amendment, Contents of the Amendment (1) "Unexamined Japanese Patent Application Publication No. 1983-1990" on page 3, lines 2 to 3 of the specification.
51299 Publication" is corrected to "Japanese Unexamined Patent Publication No. 57-51922."that's all

Claims (1)

[Claims] fll A fuel supply amount adjustment device that adjusts the amount of fuel supplied to the engine, an intake temperature sensor that is disposed in the intake passage of the engine and detects the intake air temperature, and based on the output of the intake air temperature sensor, the higher the intake temperature, the more fuel a correction means for correcting and controlling the fuel supply amount adjusting device so as to reduce the supply amount; and a specific operating state detection means for detecting an operating state in which the intake air temperature corresponding to the output of the intake air temperature sensor is higher than the actual intake air temperature. . A fuel supply device for an engine, comprising: limiting means for receiving the detection output of the specific driving state detecting means and limiting the correction control.