JPH0615829B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a device for arithmetically controlling a fuel injection mode when the internal combustion engine is started. In the following description, the internal combustion engine is abbreviated as an engine.

(Prior Art) First, a general configuration of a conventional device and a device of the present invention will be described.
With reference to the drawings, an example of the configuration of a conventional electronically controlled fuel injection device that performs fuel injection control using a microcomputer will be described.

In FIG. 1, the engine is shown generally at 7, where 1 is its cylinder and 2 is the cylinder head. Three
Is a piston to which a piston ring 4 is attached, which reciprocates in the cylinder 1 to transmit the gas pressure at the time of explosion of the air-fuel mixture in the compression stroke to the stove 5, and to rotate a crank shaft (not shown). Reference numeral 6 is a distributor, in which a rotation sensor 9 mounted on a rotating shaft that rotates in synchronization with the rotation of the crankshaft is incorporated. Reference numeral 8 is an ignition coil, 10 is an intake pipe, 11 is an exhaust pipe, 12 is an air cleaner, and 13 is a fuel injection valve which is attached to a portion of the intake pipe 10 near the intake port of the engine 7 and which is electromagnetically opened and closed. . Reference numeral 14 denotes a control unit including an electronic circuit and a micro computer, which designates a fuel injection mode, calculates a fuel injection time, that is, an energization time of the fuel injection valve 13, and drives the fuel injection valve 13, the fuel pump 15, and the like. Generate a signal. Reference numeral 16 is an intake air amount sensor that detects the amount of intake air in the intake pipe 10, 17 is a cooling water temperature sensor that detects the cooling water temperature of the engine 7, and 18 is an igniter that opens and closes the power supply to the control unit 14 and the like. It is a key switch having a switch and a starter switch for turning on and off the starting device of the engine 7. 19
Is a fuel tank, 20 is a fuel pressure adjusting valve for keeping the fuel pressure constant, and 21 is a fuel pressure adjusting valve 20 and a fuel injection valve 1.
Reference numeral 22 is a fuel pipe that communicates with the fuel cell 3, and 22 is a fuel return pipe. Reference numeral 23 is an intake air temperature sensor attached to one portion of the air cleaner 12 for detecting the temperature of intake air.

In the above configuration, the fuel injection amount for each engine 7 is controlled by the length of time that the fuel injection valve 13 is opened by the signal sent from the control unit 14.

The fuel injection amount is increased according to the engine condition, especially when the fuel vaporization is low and the cooling water temperature is high and the fuel temperature is high. In a state where it becomes light,
It is increased when it is necessary to improve the restartability of the engine. Here, the occurrence of vapor occurs at a time after the vehicle is stopped rather than when the vehicle is stopped after the vehicle is stopped, because the cooling fan is stopped by stopping the engine and the cooling air is extinguished by the traveling of the vehicle. After 20 minutes, the fuel temperature rises and vapor is more likely to be generated in the fuel pipe. At this time, the fuel temperature may even become higher than the engine cooling water temperature. When vapor is generated in this way, the air-fuel mixture supplied to the engine becomes thin, so the startability deteriorates unless the amount of fuel is increased when restarting the engine.

As a conventional device, for example, in Japanese Unexamined Patent Publication No. 56-81230 (Japanese Patent Application No. 54-157464), a fuel temperature sensor for detecting the fuel temperature is provided in the fuel pipe. There is disclosed an electronically controlled fuel injection device provided with a control unit including a CPU which determines that the temperature has risen above a preset temperature and arithmetically controls the increase of the fuel injection amount.

However, in such a conventional device, in the calculation of the fuel injection time at the time of starting the engine, the method of calculating the fuel injection amount in consideration of the high cooling water temperature and the intake air temperature for starting the engine in the high temperature state is insufficient. Therefore, it is possible that a large amount of vapor is generated, causing a vapor lock, which makes it impossible to start the engine.
Further, Japanese Patent Publication No. 54-1846 discloses a configuration in which the fuel injection amount is increased when the engine temperature is equal to or higher than a predetermined value at the time of starting, but vapor does not occur immediately after the engine is stopped. That is, it takes time for the engine heat to remain in the entire engine room after the engine is stopped. Therefore, even if the engine temperature is high, if the air temperature in the engine room has not risen so much when the amount is increased at startup, the air-fuel ratio becomes too rich because vapor does not occur, making it difficult to start the engine. was there.

(Object and Summary of the Present Invention) The present invention includes an engine temperature sensor that detects an engine temperature and an intake air temperature sensor that detects an intake air temperature, and supplies the engine based on a detection signal output from each of the sensors. An electronically controlled fuel injection device for an engine, which controls an injection amount of fuel, comprising: first determination means for determining whether or not a first condition that the temperature of the engine is a predetermined value or more is satisfied; and intake air temperature is a predetermined value or more. The second determination means for determining whether or not a certain second condition is satisfied, and the fuel injection amount is increased for a predetermined period when both the first condition and the second condition are simultaneously satisfied at the time of starting the engine. An object of the present invention is to provide an electronically controlled fuel injection device for the above engine, which is provided with a high-temperature start-up increasing means that attenuates the increase with respect to the number of injections or the time, whereby the engine temperature is high at startup. Even in such a case, the increase is prohibited when the intake air temperature is not high, so that the increase can be performed only while the vapor is reliably generated, and the air-fuel ratio is prevented from becoming overrich.

(Structure of Apparatus According to the Present Invention) Next, the structure of the fuel injection control means according to the present invention included in the control unit 14 shown in FIG. 1 is illustrated together with other elements shown in FIG. 1 related thereto. This will be described with reference to the functional block diagram of FIG.

In FIG. 4, the output line of the cooling water temperature sensor 17 shown in FIG. 1 is led to the input end of the cooling water temperature comparing means, and the output line of the intake air temperature sensor 23 is also led to the input end of the intake temperature comparing means. ing.

The cooling water temperature comparison means compares the value of the cooling water temperature detection signal output from the cooling water temperature sensor 17 with the cooling water temperature reference value,
The first output line for sending the first output signal generated when the former is equal to or less than the latter is led to the input end of the normal start mode designating means, and outputs the second output signal generated when the former exceeds the latter. The second output line is led to the input end of the intake air temperature comparison means. Further, the output end of the normal start mode designating means is connected to the input end of the fuel injection valve drive means for outputting a drive signal for the fuel injection valve 13.

Second intake air temperature comparison means outputs from the cooling water temperature comparison means
In response to the output signal from the intake air temperature sensor 23, the value of the intake air temperature detection signal is compared with the reference value of the intake air temperature, and the first output line for sending out the first output signal generated when the former is less than the latter is output. Is led to the input end of the normal start mode designating means, and the second output line for sending out the second output signal generated when the former is the latter or more is led to one input end of the high temperature starting mode designating means. .

Next, the hot start mode designating means sends out a first output signal designating operation in the hot start mode, which is generated for a predetermined period in response to the second output signal outputted from the intake air temperature comparing means. The output line is led to the input end of the fuel injection valve drive means, and the second output line for sending out the second output signal generated by the high start mode designating means after the lapse of the predetermined period is the normal start mode designating means. Is led to the input end of.

The output line of the rotation sensor 9 shown in FIG. 1 is shown as being connected to the other input end of the high temperature start mode designating means. This shows a case where the high temperature starting mode designating means uses a predetermined period during which the first output signal is generated, as an example, as a signal source for defining the predetermined number of times of fuel injection, as will be described later.

Here, the fuel injection control means according to the present invention described above is the fourth
The cooling water temperature comparing means, the intake air temperature comparing means, the normal starting mode designating means, the high temperature starting mode designating means, and the fuel injection valve driving means shown in FIG. And, the cooling water temperature comparison means, the intake air temperature comparison means, in the fuel injection control means,
The normal starting mode designating means and the high temperature starting mode designating means are constituent elements of the microcomputer included in the control unit 14, and the fuel injection valve driving means constitutes the output element thereof.

(Operation of the device according to the present invention) The operation of the fuel injection control means according to the present invention having the above-described configuration will be described with reference to FIGS. 2 and 3.

FIG. 2 is a control flow chart illustrating the operation of the fuel injection control means according to the present invention. First, step 100
When the key switch 18 shown in FIG. 1 is turned on and power is supplied to the control unit 14, the step 10
Initialization is performed in step 1, and then in step 102, a cooling water temperature signal is input from the cooling water temperature sensor 17 and an intake air temperature signal is input from the intake air temperature sensor 23. Step 103
In, the cooling water temperature is compared with the judgment reference value T _W, and when the cooling water temperature is equal to or lower than the judgment reference value T _W, step 104
Then, the operation in the normal start mode, which is the fuel injection mode of the valve opening time according to the state of the engine, which is conventionally performed, is designated. When the cooling water temperature exceeds the judgment reference value T _W , the routine proceeds to step 105. In step 105, the intake air temperature is compared with the determination reference value T _A, the process proceeds to step 104 when less than the criterion value T _A, the operation of the normal startup mode is designated. When the intake air temperature is equal to or higher than the determination reference value T _A , it is determined that the engine is currently in the bone temperature state, and the routine proceeds to step 106, where a predetermined fuel injection mode using a long valve opening time pulse is used to increase the amount of fuel. The hot start mode of operation for a specified period is specified. After the fuel injection in the high temperature start mode is performed for a predetermined period, the control process proceeds to step 104, and thereafter, the operation in the normal start mode is designated.

As can be seen from FIG. 4, the signal representing the normal start mode designated in step 104 and step 106
The signal representing the high temperature starting mode designated in 1) is sent to the input ends of the fuel injection driving means, and thereby the signal for driving the fuel injection valve is generated.

FIG. 3 illustrates a mode of controlling the injection pulse width at the time of fuel injection in the high temperature start mode. As already mentioned,
In the high temperature start mode, fuel injection is performed only for a preset period, but in the example shown in FIG. 3, fuel injection is performed for a preset number of injections (N in the figure is, for example, 20). In the beginning, fuel injection is performed with a fixed pulse width, after which the pulse width is rapidly narrowed and the fuel injection is completed 20 times. The injection period in the high temperature start mode needs to be set to a length such that vapor can be sufficiently removed.

The following modifications can be made to the embodiment of the present invention described above.

(1) Control unit 14 in the above embodiment
The micro computer included in is not only a digital type but may be an analog type.

(2) The temperature in the engine room may be used instead of the intake air temperature used to determine the state when the engine is started.

(3) The predetermined period of the high temperature start mode may be defined by a preset time (for example, 3 seconds) instead of the "fuel injection number". In that case, the rotation sensor 9 in FIG.
Is replaced by the appropriate timer.

(Effects of the Present Invention) The effects of the device of the present invention are as follows.

In the high temperature starting state of the engine, the injection amount signal is controlled in the increasing direction, so the vapor is expelled at once and the vapor lock does not occur.

Even in a high temperature starting state of the engine, it is possible to accurately determine the condition under which vapor does not actually occur from the intake air temperature and prohibit the above-mentioned increase.

At that time, the signal of the intake air temperature sensor used in a normal electronically controlled fuel injection device can be used.

High temperature increase is attenuated with the number of injections or time,
The high temperature increase can be smoothly reduced, and the engine can be operated smoothly at the time of high temperature start and immediately thereafter.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining the general configuration of a conventional device and the device of the present invention. FIG. 2 is a flow chart of arithmetic processing performed by the microcomputer contained in the control unit of the apparatus of the present invention in the configuration shown in FIG. FIG. 3 is a characteristic diagram illustrating the relationship between the number of injections and the injection pulse width when the period of fuel injection in the high temperature start mode by the device of the present invention is defined by the number of injections. FIG. 4 is a function diagram illustrating the structure of the fuel injection control means included in the control unit of the device of the present invention in the structure shown in FIG. 1 together with other related elements shown in FIG. It is a block diagram. (Explanation of symbols) 7 ... Engine, 9 ... Rotation sensor, 10 ... Intake pipe, 11 ... Exhaust pipe, 12 ... Air cleaner, 13 ... Fuel injection valve, 14 ... Control unit, 15 ... Fuel Pump, 16 ... Intake amount sensor, 17 ... Cooling water temperature sensor, 18 ... Key switch, 19 ... Fuel tank, 20 ... Fuel pressure adjusting valve, 21 ... Fuel piping, 22 ... Fuel return pipe, 23 ... … Intake temperature sensor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenichiro Kamai, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Masumi, 1-1, Showa-cho, Kariya city, Aichi prefecture Co., Ltd. (56) Reference JP-A-53-104031 (JP, A) JP-A-56-154133 (JP, A) JP-A-56-81230 (JP, A)

Claims (1)

[Claims] 1. An engine temperature sensor for detecting the temperature of an internal combustion engine, and an intake air temperature sensor for detecting an intake air temperature. The injection amount of fuel supplied to the internal combustion engine based on a detection signal output from each of the sensors. An electronically controlled fuel injection device for an internal combustion engine for controlling a temperature of the internal combustion engine, the first determination means for determining whether or not a first condition in which the temperature of the internal combustion engine is a predetermined value or more; A second determination unit that determines whether or not a certain second condition is satisfied, and the fuel injection amount is increased for a predetermined period when both the first condition and the second condition are satisfied at the same time when the internal combustion engine is started. An electronically controlled fuel injection device for an internal combustion engine, comprising: a high-temperature start-up increasing means that attenuates this increase in the number of injections or in time.