JPH0450442A - Fuel supply device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve startablity even when an engine is at low temperature by driving an air pump to accumulate pressurized air in an air cylinder after the engine starts, or except when the engine starts. CONSTITUTION:A fuel injection valve 1 is provided with an air jet exit part around the fuel injection part, which is adapted to mix pressurized air with fuel to promote atomization. Further, an air cylinder 4 for accumulating pressurized air, as a pressurized air supply device, an air pump 8 for supplying pressurized air to the air cylinder 4, a solenoid valve 5 installed to an air passage 3, are provided. In this case, a control unit 12 drives the air pump 8 except when the engine starts, to accumulate pressurized air in the air cylinder 4 and to open the solenoid valve 5 at the time of low temperature of the engine, including the time of starting the engine. Thus, since power of batteries is not used when the engine is started, load to the batteries is eliminated to prevent battery-exhaustion, and thereby there is no danger of reduction of cranking- rotating speed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a fuel supply device for an internal combustion engine, and in particular, to a fuel supply device for an internal combustion engine, and in particular to a system for supplying pressurized air to the air jetting portion of a fuel injection valve and mixing it with injected fuel when the engine is low temperature. The present invention relates to a fuel supply device for an internal combustion engine that promotes atomization.

<Prior Art> Conventional fuel supply devices for internal combustion engines include those shown below.

In other words, the fuel injection amount is set based on the intake air flow rate Q, the engine speed N, etc., and the amount is injected into the engine by the fuel injection valve at a predetermined timing synchronized with the engine rotation to maintain an appropriate air-fuel ratio. I have to.

Furthermore, when starting the engine at low temperature, the auxiliary fuel injection valve for low temperature starting also injects fuel to increase the amount of fuel and improve the startability of the engine.

<Problems to be Solved by the Invention> However, in such conventional fuel supply devices, fuel is injected at low pressure (for example, 2.5 to 3 kg/c
Because of this, the injected fuel has poor atomization and atomization.Especially when the engine temperature is low, the injected fuel is difficult to vaporize, making it impossible to form a mixture with the air-fuel ratio necessary for starting in the combustion chamber. There were problems with the time required from start to independent operation and the inability to start.

In addition, the fuel that has accumulated in the combustion chamber without being vaporized may be discharged as hydrocarbons or unburned mixture after startup.
There was also the problem of exhaust gas deterioration.

Therefore, pressurized air is supplied to the fuel by a pressurized air source at the same time as the fuel is injected to atomize the fuel and promote vaporization, thereby improving startability when the engine is cold.

However, when using an air cylinder filled with pre-pressurized air as a source of pressurized air, when the pressurized air in the air cylinder flows out and becomes empty, it must be refilled and the air remains. There was a problem in that maintenance for checking the amount and replenishing was complicated.

Additionally, if the air pressure required to atomize the fuel during startup is higher than the air pressure of the air accumulated in the air cylinder, the desired atomization level may not be obtained and startup may become impossible. There was also the issue of gender.

In addition, when using an air pump as a pressurized air source, the air pump is driven at startup, so power is required at startup, and when battery power is used for this, battery power consumption Not only does this increase, making it easier for the battery to run out, but since power is supplied to the air pump, the cranking speed decreases, conversely impeding startability. Ta.

Further, when the fuel contains alcohol, the higher the alcohol concentration, the higher the atomization level of the injected fuel needs to be. However, by adapting to high alcohol concentrations,
If you set the air pump to drive, there is a problem that when the alcohol concentration is low, it will consume more power than necessary, increasing the load on the battery, and making it easier for the battery to deteriorate or die. Ta.

SUMMARY OF THE INVENTION In view of these conventional problems, it is an object of the present invention to provide a fuel supply system for an internal combustion engine that has good startability and operability even when the engine temperature is low.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a method for supplying pressurized air to the air jet section of the fuel injection valve when the engine is low temperature and mixing it with the injected fuel to promote atomization. In the fuel supply device for an internal combustion engine, the pressurized air supply device includes an air cylinder that accumulates pressure of pressurized air to be supplied to the air jetting portion, an air pump that supplies pressurized air to the air cylinder, and the air pump that supplies pressurized air to the air cylinder. an on-off valve installed in an air passage between an air cylinder and the air jetting section; and an on-off valve that drives the air pump to accumulate pressure in the air cylinder at times other than when starting the engine, and operates the on-off valve at low temperatures including when starting the engine. The configuration includes a control device that opens the valve.

In addition to the basic configuration described above, the configuration includes alcohol concentration detection means for detecting the alcohol concentration in the fuel, and air pressure setting means for setting the air pressure to be accumulated in the air cylinder according to the detected alcohol concentration. Good too.

Further, the configuration of the control device may be as shown in (a) or (b) below.

(a) An air pressure testing device that detects the air pressure in the air cylinder, and an air pump drive that compares the detected air pressure with a set value and drives the air pump during self-sustaining operation after engine startup when the detected air pressure is lower than the set value. means.

(b) An air pressure detection means for detecting the air pressure in the air cylinder, and an air pump that compares the detected air pressure with a set value and drives the air pump before starting the engine when the engine key switch is turned on when the detected air pressure is lower than the set value. and a driving means.

<Operation> According to the above configuration, the control device drives the air pump to accumulate pressure in the air cylinder at times other than when the engine is started, and opens the on-off valve when the engine is low in temperature to increase the pressure in the air cylinder. Air is supplied to the air jet of the fuel injector to promote atomization of the injected fuel.

According to this, since the air pump is not driven when the engine is started, there is no need to put a burden on the battery when starting the engine.

In addition, when using alcohol-mixed fuel, the alcohol concentration detection means detects the alcohol concentration in the fuel, and the air pressure is The setting means accumulates air pressure in the air cylinder according to the alcohol concentration.

The air pump can be driven other than when starting the engine by detecting the air pressure in the air cylinder using the air pressure detection means of the control device, and starting the engine when the air pressure is lower than the set pressure using the air pump driving means. Later, by driving the air pump or by the air pressure detection means of the control device,
The air pressure in the air cylinder is detected, and when the air pressure is lower than the set pressure, the air pump is driven by the air pump driving means when the engine key switch is turned on prior to starting the engine.

<Example> Examples according to the present invention will be described below based on FIGS. 1 to 4.

First, the system of the first embodiment will be explained with reference to FIG.

A fuel injection valve 1 is arranged facing an intake manifold 2 of an engine. The fuel injection valve 1 has an air injection part (both not shown) surrounding the fuel injection part, and can mix pressurized air with the injected fuel to promote atomization.

The air jetting part is connected to an air cylinder 4 through an air passage 3, and a solenoid valve 5 as an on-off valve is interposed in the air passage 3 on the air cylinder 4 side (upstream side), and
A check valve 6 for preventing backflow is interposed on the air jet side (downstream side).

The air cylinder 4 is connected to an air pump 8 by another air passage 7.
The air passage 7 is connected to the air pump 8 side (
A check valve 9 is installed on the upstream side to prevent backflow.
Further, an atmosphere opening port 10 having a safety valve 10a that opens at a predetermined pressure or higher is branched on the air cylinder 4 side (downstream side).

A driving motor 11 is connected to the air pump 8.

The control unit 12 is based on signals from a water temperature sensor 13 that detects the engine cooling water temperature as a representative of the engine temperature, a pressure sensor 14 that detects the air pressure in the air cylinder 4, and a start switch (ST-5W) 15. The operation of the fuel injection valve 1, solenoid valve 5, and motor 11 is controlled.

Here, the control unit 12 and the pressure sensor 14 as pressure detection means constitute a control device.

Next, the air pump drive control routine as the air pump drive means will be explained with reference to the flowchart in FIG.

In step 10 (denoted as S10 in the figure, the same applies hereinafter), it is determined whether the engine has been started (YES) or not (No).

In other words, after the start switch 15 has been switched from on to off, it is determined whether (YES) or not (NO), and N
If o, the routine ends as is. That is, this is because the air pump 8 is not driven while the engine is starting.

If YES, proceed to step 2o, and press the pressure sensor 14.
The air pressure Pb inside the air pump 4 detected by the above is input.

In step 30, the air pressure Pb is less than a set value Pa preset as the air pressure inside the air cylinder 4 (Y
ES) or not (NO), and if NO, that is,
When the air pressure pb in the air cylinder 4 reaches the set value Pa, there is no need to drive the air pump 8, so the routine ends as is, but if YES, that is, the air pressure pb in the air cylinder 4 If the set value Pa has not been reached, the process proceeds to step 40, where the motor 11 is operated to drive the air pump 8.

Then, in step 50, the air pressure pb in the air cylinder 4 is
It is determined whether (YES) or not (NO) becomes greater than or equal to the set value Pa.

If NO, that is, if the air pressure pb in the air cylinder 4 has not reached the set value Pa, return to step 40 and operate the motor 11 until the air pressure pb in the air cylinder 4 reaches the set value Pa. The air pump 8 continues to be driven.

After that, the pressure inside the air cylinder 4 increases, and the air pressure Pb reaches the set value Pa (the determination in step 50 becomes YES).
Then, in step 60, the operation of the motor 11 is stopped, the driving of the air pump 8 is stopped, and the routine is ended.

As explained above, after starting the engine, air pump 8
is driven to cause the air cylinder 4 to accumulate pressurized air.

Then, the pressurized air stored in the air cylinder 4 is released by opening the solenoid valve 5 when the engine is at low temperature, including when starting the engine, that is, when the detected value by the water temperature sensor 13 is below a predetermined value T. , pressurized air is supplied to the air jet section of the fuel injection valve 1, mixed with the injected fuel, promotes atomization, and is efficiently mixed with air to obtain a mixture with an appropriate air-fuel ratio. can.

In this embodiment, the pressurized air is supplied to the fuel injection valve for normal use, but the pressurized air is supplied to the auxiliary fuel injection valve for low-temperature starting. Good too.

A second embodiment will be explained.

In contrast to the system of the first embodiment, the system of the second embodiment includes a concentration sensor 16 as an alcohol concentration detection means for detecting the concentration of alcohol such as methanol in fuel, as shown by the broken line in FIG. It was established.

The air pump drive control routine as the air pump drive means will be explained with reference to the flowchart in FIG.
The same step numbers are given to the same parts as in the flowchart of FIG. 2, and the explanation is omitted.

After the determination in step 10, in step 11, the alcohol concentration Ca in the fuel detected by the concentration sensor 16 is input.

In step 12, a set value Pa of the air pressure in the air cylinder 4 is set according to the alcohol concentration Ca.

Specifically, the higher the alcohol concentration Ca, the higher the set value Pa of the air pressure of the pressurized air.

Then, in step 20, the air pressure Pb in the air cylinder 4 is
is input, and in step 21 it is determined whether the air pressure pb is less than the set value Pa. The same applies below.

Even as explained above, the same effects as in the first embodiment can be obtained, and furthermore, the set value Pa of the air pressure stored in the air cylinder 4 is set according to the alcohol concentration Ca. Therefore, in order to obtain a proper atomization state, the higher the alcohol concentration Ca, the higher the air pressure can be met.

In addition, by setting a predetermined water temperature value T, which is the criterion for determining when the engine is low, that is, determining whether to supply pressurized air, according to the alcohol concentration Ca, the control becomes more suitable for the engine condition. I can do it.

A third embodiment will be explained.

The system of the third embodiment is similar to the system of the second embodiment.

The method for controlling the drive of the air pump as the air pump driving means includes executing the control routine shown in the flowchart of FIG. 4 in addition to the control routine shown in the flowchart of FIG.

Note that the same step numbers are given to the same parts as in the flowchart of FIG. 3, and the description thereof will be omitted.

Instead of step 10, step 10' is executed.

In step 10', when the engine key switch is turned on (when the power is turned on to the control unit I2) (YE
S) or not (NO), and if NO, terminate the routine as it is, or if YES, proceed to step 11.
Proceed to the following.

After step 60, that is, after the air pressure Pb in the air cylinder 4 reaches the set value Pa, in step 70,
Enable cranking and end the routine. In other words, cranking (engine starting) is not possible until the air pressure pb reaches the set value Pa, in order to prevent cranking from starting while the air pump 8 is running and putting a strain on the battery. be.

Even as explained above, it is possible to obtain the same effects as in the second embodiment, and furthermore, even when the engine key switch is turned on, if pressurized air needs to be supplied into the air cylinder 4, the air Since air can be supplied into the air cylinder 4 by the pump 8, before turning on the engine key switch (
In other words, even if the air pressure in the air cylinder 4 drops while the engine is stopped, the necessary amount of pressurized air will be supplied to atomize the injected fuel when the engine is started. Air pressure can be provided in the air cylinder 4.

<Effects of the Invention> As explained above, in the past, pressurized air was supplied from an air cylinder or by driving an air pump when starting the engine when the engine was cold. The air pump is driven to accumulate pressure in the air cylinder after the engine starts or when the engine key switch is turned on, other than when the engine is started.

This improves the maintainability of the air cylinder, and since the battery power used to drive the air pump is not used during startup, the burden on the battery is eliminated, preventing the battery from dying and reducing the cranking rotation speed. This has the effect of eliminating the fear of

Furthermore, since the alcohol concentration in the fuel is detected and pressurized air at a corresponding pneumatic pressure is supplied to the air jetting section, an advantage is obtained in that an optimum atomization state can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a system showing a first embodiment of the present invention;
FIG. 2 is a flowchart showing the control contents of the first embodiment;
FIG. 3 is a flowchart showing the control contents of the second embodiment;
FIG. 4 is a flowchart showing the control contents of the third embodiment. ■...Fuel injection valve 3...Air passage 4...
Air cylinder 5... Solenoid valve 8... Air pump 11... Motor 12... Control unit 13... Water temperature sensor 14... Pressure sensor 15... Start switch 16... Concentration sensor

Claims (4)

[Claims] (1) In a fuel supply device for an internal combustion engine that supplies pressurized air to the air jet part of a fuel injection valve when the engine is low temperature and mixes it with the injected fuel to promote atomization, as a pressurized air supply device, an air cylinder for accumulating pressurized air to be supplied to the air jet section; an air pump for supplying pressurized air to the air cylinder; and an air passage interposed between the air cylinder and the air jet section. An internal combustion engine characterized by being provided with an on-off valve and a control device that drives the air pump to accumulate pressure in an air cylinder at times other than when the engine is started, and opens the on-off valve at low temperatures including when the engine is started. Fuel supply device. (2) Claim 1 further comprising an alcohol concentration detection means for detecting the alcohol concentration in the fuel, and an air pressure setting means for setting the air pressure to be accumulated in the air cylinder according to the detected alcohol concentration. Fuel supply device for the internal combustion engine described. (3) The control device includes an air pressure detection means that detects the air pressure in the air cylinder, and compares the detected air pressure with a set value and drives the air pump during self-sustaining operation after engine startup when the detected air pressure is lower than the set value. 3. The fuel supply system for an internal combustion engine according to claim 1, further comprising: an air pump driving means. (4) The control device includes an air pressure detection means that detects the air pressure in the air cylinder, and an air pump that compares the detected air pressure with a set value and, if the detected air pressure is lower than the set value, starts the air pump when the engine key switch is turned on. 3. The fuel supply system for an internal combustion engine according to claim 1, further comprising an air pump driving means for driving the fuel supply system.