JPH0426687Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel injection control device for injecting fuel into an automobile engine, and in particular to a canister that purges evaporative gas (fuel vapor) in a fuel tank to an intake manifold. The present invention relates to a fuel injection control device having a type of fuel injection control device.

[Conventional technology]

Conventionally, as a fuel injection control device for automobiles, the fifth
The one shown in Fig. 6 is known.

In the figure, reference numeral 1 denotes an automobile engine, and the engine 1 is provided with an injection valve 2 that injects fuel into a combustion chamber, and an intake manifold 3 that takes in outside air. An air flow meter 4 for measuring the amount of intake air Q and a throttle valve 5 are provided, and a throttle valve switch 6 is provided opposite the throttle valve 5, and the throttle valve switch 6 detects the throttle opening degree. It's becoming like that.

7 is a fuel tank for storing fuel 8; 9 is a fuel pump provided in the fuel tank 7; 10 is a fuel pipe connecting between the fuel pump 9 and the injection valve 2; A filter 11 and a pressure regulator 12 are provided. here,
The pressure regulator 12 is connected to the intake manifold 3 via a control pressure pipe 13, and guides the positive pressure or negative pressure in the intake manifold 3 as a control pressure, and adjusts the fuel pressure according to the control pressure.
Control at 2.0 to 3.0Kg/cm ² , excess oil is returned to pipe 14
is returned to the fuel tank 7 via.

15 is a three-way solenoid valve provided in the middle of the control pressure pipe 13; 16 is an air compressor connected to the three-way solenoid valve 15 via an air pipe 17; the air compressor 16 is 1.2 to 1.5 kg/cm ² The three-way solenoid valve 15 normally communicates with the control pressure pipe 13, and communicates the control pressure pipe 13 with the air pipe 17 in response to a valve control signal from a control device 23, which will be described later. Here, when the fuel temperature rises to 80°C, vapor is generated in the fuel pumped through the fuel pipe 10, and the air-fuel ratio of the fuel injected from the injection valve 2 tends to be lean.
It is necessary to increase the fuel pressure to make the fuel richer. Therefore, in this case, the control device 23 outputs a valve control signal to the three-way solenoid valve 15, and compressed air from the air compressor 16 is guided to the pressure regulator 12 as a control pressure to increase the fuel pressure.

18 is a canister for storing evaporative gas generated in the fuel tank 7;
As shown in the figure, a casing 18A, activated carbon 18B filled in the casing 18A to temporarily absorb evaporated gas, a fresh air introduction port 18C formed at the bottom, and an inflow port formed at the lid. 1
8D, a purge control valve 18E that is provided on the lid and opens using the negative pressure in the intake manifold 3 as back pressure, and an outlet 18F that exhausts evaporative gas when the purge control valve 18E opens. ,
It is roughly composed of a back pressure inlet 18G. Here, the inlet 18D of the canister 18 is connected to the inside of the fuel tank 7 via an inflow pipe 19 and a check valve 20, and the outlet 18F is connected to the downstream side of the throttle valve 5 in the intake manifold 3 via an outflow pipe 21. The back pressure introduction port 18G is connected to a position upstream of the throttle valve 5 in the intake manifold 3 via a back pressure introduction pipe 22.

The canister 18B having the above configuration allows the evaporated gas generated in the fuel tank 7 to flow in from the inflow pipe 19 and stores it in the activated carbon 18B, while the purge control valve 18E is operated by the intake manifold during off-idle when the throttle valve 5 starts opening. The valve is opened by introducing the negative pressure generated in the intake manifold 3 through the back pressure introduction pipe 22, and the stored evaporative gas is purged from the outflow pipe 21 into the intake manifold 3.

Furthermore, 23 indicates a control device constituted by, for example, a microcomputer, and the control device 2
The input side of 3 is connected to an air flow meter 4, a throttle valve switch 6, a crank angle sensor 24 that detects the rotation speed N of the engine 1, as well as a start switch, a water temperature sensor, a fuel temperature sensor, a vehicle speed sensor, etc., and outputs. The side is connected to the injection valve 2, three-way solenoid valve 15, etc.

Here, the control device 23 calculates the basic injection amount Tp from the intake air amount Q and the engine rotation speed N as follows: Tp=K×Q/N...(1) where K: a constant, and Injection amount Ti is Ti = Tp × α × α′ × Co + Ts ... (2) where, α: Air-fuel ratio fieldback correction coefficient α': Basic air-fuel ratio learning correction coefficient C _O : Various correction coefficients T _S : Voltage correction It has the function of calculating as a coefficient and outputting an injection pulse with a predetermined duty to the injection valve 2 based on the calculation result, and also has the function of outputting the above-mentioned valve control signal to the three-way solenoid valve 15 when the fuel temperature is high. are doing.

The fuel injection control device configured as described above, when the engine 1 is started by the start switch, determines the opening degree of the throttle valve 5, the intake air amount Q measured by the air flow meter 4, and the crank angle sensor 2.
From the engine speed N according to 4, the basic injection amount Tp
is calculated by equation (1), and the injection amount Ti is calculated by equation (2) from each correction coefficient, an injection pulse of a predetermined duty is output to the injection valve 2, and the air-fuel ratio A/
Control is performed so that F is always constant.

On the other hand, the canister 18 stores the evaporative gas generated in the fuel tank 7, and at the timing when the throttle valve 5 becomes off-idle, the purge control valve 18E
When the valve opens, the evaporative gas stored in the intake manifold 3 is discharged and sent to the engine 1, where it is combusted together with the fuel.

[Problem that the invention attempts to solve]

By the way, the return pipe 14 is connected to the pressure regulator 1.
2. It is arranged in the engine room together with the injection valve 2, etc., and the fuel flowing in the return pipe 14 absorbs the heat in the engine room and cools the engine 1 etc. For this reason, the return pipe 14
The fuel temperature of the return oil returned to the fuel tank 7 from
For example, the temperature has risen to 70-80℃.

In this way, the return oil from the return pipe 14 into the fuel tank 7 is normally cooled by the fuel 8 inside, but as shown in FIG. When the temperature of the fuel 8 becomes too hot, the fuel temperature of the fuel 8 also rises to 70 to 80°C.

As the fuel temperature rises in this manner, the amount of evaporative gas generated within the fuel tank 7 naturally increases. Therefore, the amount of absorption by the activated carbon 18B of the canister 18 also increases. As a result, when the purge control valve 18E of the canister 18 opens, the amount of evaporative gas purged from the outflow pipe 21 into the intake manifold 3 also increases in proportion to the amount of evaporative gas generated in the fuel tank 7. become.

However, in the prior art, the control device 23
Although the air-fuel ratio A/F is controlled to be constant, no consideration is given to the amount of evaporative gas purged into the intake manifold 3, that is, the amount of gasoline purged. As a result, when the amount of evaporative gas increases, the air-fuel ratio A/F tends to become rich, and in the worst case, there is a risk of engine stalling.

The present invention was developed in view of the problems of the prior art, and is a fuel injection system that controls the air-fuel ratio to be constant even when evaporative gas is discharged, so that the overall air-fuel ratio can be kept constant at all times. The purpose is to provide a control device.

[Means for solving problems]

In order to solve the above problems, the present invention provides a fuel tank for storing fuel, a fuel pump for discharging the fuel in the fuel tank, and an injection valve for injecting the fuel supplied from the fuel pump into the engine of an automobile. and an air flow meter that is installed in the intake manifold of the engine and measures the amount of intake air, and calculates the amount of fuel to be injected by the injector from the amount of air measured by the air flow meter and the rotational speed of the engine. A canister that is connected to the fuel tank via an inflow pipe and connected to the intake manifold via an outflow pipe, and stores evaporative gas generated in the fuel tank inside the fuel injection control device. an air compressor connected to the outflow pipe via an air pipe; and an air compressor provided between the outflow pipe and the air pipe, which is opened and closed by a control signal from the control device, and is connected to the air compressor. and a solenoid valve that simultaneously discharges air from the canister and evaporative gas from the canister to the intake manifold.

[Effect]

With this configuration, when each solenoid valve opens, the air from the compressor and the evaporative gas from the canister are combined and purged from the outflow pipe into the intake manifold, so the amount of air and evaporative gas are balanced. By setting the ratio appropriately, the overall air-fuel ratio can be maintained constant.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 4. Note that the same components as those in the prior art are given the same reference numerals, and their explanations will be omitted.

1 to 3 show the first embodiment. In the figures, 31 is a canister used in this embodiment,
The canister 31 is the canister 1 according to the prior art.
8, the inside is filled with activated carbon, and the inlet is connected to the fuel tank 7 via the inflow pipe 32 and check valve 33, but the purge control valve 18E, back pressure introduction pipe 22, etc. of the prior art are not used. The inside of the canister 31 is an outflow pipe 34.
The difference is that it is connected in direct communication with the downstream position of the throttle valve 5 in the intake manifold 3 via the intake manifold 3.

Furthermore, an air mixer 35 and a normally closed solenoid valve 36 shown in FIG. , another normally closed solenoid valve 38 is provided in the middle of the air pipe 37. Here, the air mixer 35 is configured, for example, as an ejector as shown in FIG. A mixer 35C located at the next stage of
It consists of a differential user 35D connected to the intake manifold 3 via a solenoid valve 36, and an air nozzle 35E extending from the inflow pipe 35A into the throttle pipe 35B and connected to the air compressor 16 via a solenoid valve 38. , by blowing out compressed air from the air nozzle 35E, the evaporative gas from the canister 31 is sucked,
After mixing in the mixing pipe 35C, the mixture is discharged to the intake manifold 3.

Further, numeral 39 indicates a control device used in this embodiment, and the control device 39 is the control device 2 according to the prior art.
Similarly to 3, the injection amount Ti is calculated based on equations (1) and (2), and an injection pulse of a predetermined duty is output to the injection valve 2. Also, when the fuel temperature is high, the three-way solenoid valve 15 is controlled. In addition to having the function of outputting a signal, it also stores the program shown in FIG.
6 and 38 at the same time for a predetermined period of time (for example, 10 seconds).

The present embodiment is configured as described above, and its operation will be described next.

First, the basic operation of the fuel injection control device is that when the engine 1 is started by the start switch, the opening of the throttle valve 5 is determined, the intake air amount Q is determined by the air flow meter 4, and the engine rotational speed is determined by the crank angle sensor 24. From N, basic injection amount
Tp is calculated by equation (1), and the injection amount Ti is calculated from each correction coefficient by equation (2).
There is no difference from the prior art in that an injection pulse of a predetermined duty is outputted to control the air-fuel ratio A/F to be constant.

However, in this embodiment, when the evaporative gas is purged into the intake manifold 3 at the timing when the throttle valve 5 is idle-off, the evaporative gas is purged in a mixed state with compressed air, and the air-fuel ratio A/ The difference is that F is prevented from becoming rich.

This will be described with reference to the flowchart shown in FIG.

In FIG. 3, when the process is started, the control device 39 reads the engine speed N from the crank angle sensor 24 (step 1), and reads the opening degree of the throttle valve 5 from the throttle valve switch 6 (step 1). 2).

Next, in step 3, the engine speed N is
Monitor whether the engine speed has reached 2000 rpm or higher. If the evaporative gas is discharged below this, there is a risk of engine stalling, so return to step 1 and continue monitoring.
On the other hand, when the determination in step 3 is ``YES'', the process moves to the next step 4 and monitors whether or not the throttle valve 5 has become idle-off.

If the answer is “YES” in step 4 above,
Since this is the timing when the inside of the intake manifold 3 becomes negative pressure, the control device 39 outputs a valve opening signal to each of the solenoid valves 36 and 38 (step 5). As a result, the compressed air from the air compressor 16 is blown out from the air nozzle 35E of the air mixer 35 via the air pipe 37 and the solenoid valve 38, and the evaporative gas in the canister 31 is blown out from the air nozzle 35E of the air mixer 35 via the outflow pipe 34. 35 , mixed with compressed air, and then discharged into the intake manifold 3 via a solenoid valve 36 .

Furthermore, the control device 39 monitors whether 10 seconds have elapsed after outputting the valve opening signal (step 6), and if the determination is "YES", it sends a valve opening signal to each solenoid valve 36, 38 in step 7. output, stop purging of evaporated gas, and return to step 1.

Thus, in this embodiment, by appropriately setting the valve opening degree of the solenoid valve 38 and adjusting the compressed air amount a, the air-fuel ratio a/ for the evaporative gas is determined from the relationship with the evaporative gas amount, so that A/F≒a /=constant...(3) Can be set. As a result, even when the evaporative gas is purged, a constant air-fuel ratio can be maintained at all times, and the tendency toward enrichment as in the prior art can be reliably prevented.

Next, FIG. 4 shows a second embodiment of the present invention.

The same components as those in the first embodiment are given the same reference numerals.The feature of this embodiment is that the solenoid valve 36 according to the first embodiment is installed as a solenoid valve 41 in the middle of the outflow pipe 34 and in the canister. 31
and the air mixer 35.

Since the present embodiment is configured in this way, by appropriately setting the opening degrees of the solenoid valves 38 and 41, the compressed air amount a and the evaporative gas amount can be adjusted independently, and the air-fuel ratio a/
can be set more accurately.

[Effect of idea]

The fuel injection control device according to the present invention is as described in detail above, and since the evaporative gas and compressed air are discharged together from the canister to the intake manifold, the relationship between the evaporative gas amount and the compressed air amount can be considered. The air-fuel ratio can be kept constant even when evaporative gas is discharged, the tendency of the air-fuel ratio to become rich can be prevented, and the engine can be operated satisfactorily.

[Brief explanation of the drawing]

1 to 3 relate to a first embodiment of the present invention, in which FIG. 1 is an overall configuration diagram of a fuel injection control device according to this embodiment, FIG. 2 is a longitudinal sectional view of an air mixer,
Figure 3 is a flowchart showing the control process of the solenoid valve;
FIG. 4 is a configuration diagram of main parts of a fuel injection control device showing a second embodiment, FIGS. 5 and 6 relate to the prior art, and FIG. 5 is an overall configuration diagram of a fuel injection control device according to the prior art. FIG. 6 is a longitudinal sectional view of the canister. 1...Engine, 2...Injection valve, 3...Intake manifold, 4...Air flow meter, 5...
...Throttle valve, 7...Fuel tank, 8...
Fuel, 12...Pressure regulator, 16...Air compressor, 31...Canister, 32...Inflow pipe, 34...Outflow pipe, 35...Air mixer, 36, 38, 41...Solenoid valve, 37 …
...Air piping, 39...Control device.

Claims (1)

[Scope of utility model registration request] A fuel tank that stores fuel, a fuel pump that discharges the fuel in the fuel tank, an injection valve that injects the fuel supplied from the fuel pump to the engine of the automobile, and a fuel tank that is installed in the intake manifold of the engine and that injects intake air. A fuel injection control device includes an air flow meter that measures the amount of air flowing in, and a control device that calculates the amount of fuel to be injected by the injector based on the air amount measured by the air flow meter and the engine rotational speed and controls the injector. A canister is connected to the fuel tank via piping and is also connected to the intake manifold via an outflow pipe, and stores the evaporative gas generated in the fuel tank inside, and is connected to the outflow pipe via an air pipe. An air compressor is provided in the middle of the outflow pipe and the air pipe, respectively, and is opened and closed by a control signal from the control device to simultaneously supply air from the air compressor and evaporative gas from the canister to the intake manifold. A fuel injection control device comprising a solenoid valve for discharging fuel.