JPH0455255Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a fuel injection device for an internal combustion engine, and is particularly applicable to cases where the assist air injection part of the fuel injection valve is clogged, and air leaks from the assist air introduction passage. This invention relates to a fuel injection device that automatically issues a warning in the event of a leak.

[Conventional technology]

A device that promotes atomization of fuel by colliding air injected from an air passage provided around a fuel injection valve with fuel injected from a fuel injection port is disclosed in, for example, Japanese Patent Laid-Open No. 57-99267. It is disclosed in the publication No.

Additionally, there is a device that introduces assist air into the mixing chamber downstream of the fuel injection outlet with a swirling motion to prevent the fuel injection hole from being clogged with dirt mixed in the assist air. , disclosed in Japanese Patent Application Laid-Open No. 179367/1983.

The air introduction passage that guides assist air to the fuel injection valve is usually connected to the upstream side of the throttle valve via a flow rate control means, and the amount of assist air that corresponds to the engine operating conditions is supplied to the fuel injection valve. It is becoming more and more common.

[The problem that the idea aims to solve]

However, in a fuel injection device equipped with an air assist mechanism, if air leaks occur in the air introduction passage, the air-fuel ratio between each cylinder will vary, making it difficult to control the air-fuel ratio, and causing combustion to deteriorate. occurs. In addition, if a leak occurs in the air introduction passage, air that does not pass through the air cleaner will be guided to the combustion injection valve, which may cause the piston to seize due to foreign matter or cause the air injection part of the fuel injection valve to become clogged. and worsening of combustion, and
This leads to problems such as increased HC emissions and decreased response.

The above-mentioned Japanese Patent Application Laid-open No. 57-179367 is effective against clogging caused by foreign matter such as dust, but has no effect on air leakage from the air introduction passage.

Focusing on the above-mentioned problems, the present invention has been developed to provide assistance when an air leak occurs in the air introduction passage that guides assist air to the fuel injection valve, or when the air injection part of the fuel injection valve is clogged with foreign matter. An object of the present invention is to provide a fuel injection device that can notify an abnormality in an air mechanism.

[Means to solve the problem]

The fuel injection device of the present invention that meets this purpose is a fuel injection device for an internal combustion engine that promotes atomization of the fuel by colliding assist air with the injected fuel. ,
A first pressure sensor for detecting the pressure in the intake passage is provided, and a second pressure sensor for detecting the pressure in the air introduction passage is provided in an air introduction passage connected to the intake passage and guiding assist air to the fuel injection valve. Install a sensor,
an electronic control device to which the first pressure sensor and the second pressure sensor are connected and which controls the operation of the engine;
It has an abnormality determination function that determines that the air assist mechanism is abnormal when the difference between the pressure in the intake passage and the pressure in the air introduction passage becomes larger than a preset value.

[Effect]

In the fuel injection device configured in this manner, if no air leakage occurs in the intake passage, the difference between the pressure in the intake passage and the pressure in the air introduction passage does not become very large. If there is an air leak in the air introduction passage or the fuel injection valve is clogged, the pressure in the air introduction passage will become close to atmospheric pressure.
The difference between the pressure in the intake passage and the pressure in the air introduction passage increases. The allowable range of the pressure difference between the pressure in the intake passage and the air introduction passage is set in advance in the electronic control device, so if the pressure difference between the two passages becomes larger than a predetermined value, an abnormality alarm will be issued to the driver. It will be done.

This allows the driver to recognize that the air assist mechanism is abnormal, and the above problem can be resolved by taking appropriate measures.

〔Example〕

Hereinafter, preferred embodiments of the fuel injection device according to the present invention will be described with reference to the drawings.

1 to 4 show an embodiment of the present invention. In the figures, 1 indicates an engine body, and 2 is slidably fitted into a cylinder bore of a cylinder block (not shown). The piston is shown. The combustion chamber 3 communicates with an intake passage 5 via an intake valve 4. A surge tank 6 is provided in the middle of the intake passage 5, and a strotztle valve 7 is provided upstream of the surge tank 6. An air cleaner 8 is provided at the most upstream side of the intake passage 5, and an air flow meter 9 is provided between the air cleaner 8 and the strottle valve 7 to measure the flow rate of intake air flowing into the intake passage 5.

A fuel injection valve 10 that injects fuel into the combustion chamber 3 is provided immediately upstream of the intake valve 4 . As shown in FIG. 2, the fuel injection valve 10 has a distal end portion fixed to a cylinder head 12 via a seal ring 11. The fuel injection valve 10 has a fuel injection hole 13 for metering fuel, and the fuel injected from the fuel injection hole 13 flows through injection holes 14a and 14b.
It is designed to be branched into two directions. ,
Further, the injection holes 14a and 14b are connected to an annular air introduction chamber 16 located on the outer periphery of the injection holes 14a and 14b via passages 15a and 15b serving as air injection portions, and this air introduction chamber 16 is connected to an air introduction passage 17. has been done. That is, the fuel injected from the fuel nozzle hole 13 flows directly downstream of the nozzle hole 13 through the passage 15a,
It collides with the assist air ejected from 15b, and atomization is promoted.

The upstream end of the air introduction passage 17 is connected to the flow rate control means 1
8 between the throttle valve 7 of the intake passage 5 and the air flow meter 9. The surge tank 6 of the intake passage 5 is provided with a first pressure sensor 19 that detects the pressure within the intake passage 5 . Further, a second pressure sensor 20 is provided between the fuel injection valve 10 of the air introduction passage 17 and the flow rate control means 18 to detect the pressure within the air introduction passage 17.

The first pressure sensor 19 and the second pressure sensor 20 are connected to an electronic control unit (ECU) 21 that controls the operation of the engine 1. Further, an air flow meter 9 and an engine rotation speed sensor (not shown) are connected to the electronic control device 21. That is, the pressure Pm in the intake passage 5, the pressure Pa in the air introduction passage 17, the intake air amount Q, and the engine rotation speed NE are input to the electronic control device 21, respectively.

The electronic control device 21 controls the pressure Pm in the intake passage 5.
It has an abnormality determination function that determines that there is an abnormality in the air assist mechanism when the difference between the pressure Pa and the pressure Pa in the air introduction passage 17 becomes larger than a preset value. As shown in FIG. 3, the electronic control unit 21 stores a map in which the horizontal axis is the engine speed NE and the vertical axis is the engine speed NE relative to the intake air amount Q. pressure
When the differential pressure between Pa and Pm is greater than a preset value, there is an abnormality in the air assist function, that is, an air leak has occurred in the air introduction passage 17, or the passages 15a and 15b of the fuel injection valve 10 are clogged. It is determined whether This map includes, as shown in the figure.
For example, differential pressures ΔP ₁ , ΔP ₂ , and ΔP ₃ between pressure Pa and pressure Pm in a low load area, a medium load area, and a high load area are stored, respectively. That is, differential pressure ΔP ₁ is stored as corresponding to the low load region, differential pressure ΔP ₂ is stored in the medium load region, and differential pressure ΔP ₃ is stored in the high load region. In this embodiment, in order to prevent erroneous judgments, each differential pressure △P ₁ , △P ₂ , △P ₃ is multiplied by an erroneous judgment prevention coefficient a, and each differential pressure a・When the actually detected differential pressure Pa-Pm is larger than △P ₁ , a・△P ₂ , a・△P ₃ (correction value),
An alarm is issued from the electronic control device 21 to the alarm means 22.

Next, the operation of the above fuel injection device will be explained.

FIG. 4 shows a flowchart of abnormality determination of the air assist mechanism. As shown in the figure, the CPU (not shown) in the electronic control unit 21 is interrupted at a predetermined time, and in step 31, the engine rotation speed NE is detected by a rotation speed sensor (not shown). Next, the process proceeds to step 32, where the intake air amount Q is detected, and then the process proceeds to step 33. Third
The map shown in the figure shows the engine speed NE on the horizontal axis.
The vertical axis shows the intake air amount Q and the engine speed.
In step 33, when the signals from the engine speed sensor (not shown) and the air flow meter 9 are input, the differential pressure △P ₁ set for each engine speed range is determined. , △P ₂ , △
One of _P3 is selected.

When this step is completed, proceed to step 34,
Here, the pressure Pa in the air introduction passage 17 is detected by the second pressure sensor 20, and the process further proceeds to step 35, where the pressure Pm in the intake passage 5 is detected by the first pressure sensor 19. When the pressures in both passages are detected, the process proceeds to step 36, where the detected pressure difference in both passages is compared with the differential pressure ΔP selected from the map multiplied by a coefficient a. That is, if differential pressure △P ₁ is selected, a・△
P ₁ and Pa−Pm are compared, and a・△P ₁ <Pa−Pm
If so, proceed to step 37 and display that the air assist function is abnormal. In step 37,
When a・ΔP ₁ >Pa−Pm, it is determined to be normal, and the process returns to the start and the above steps are repeated again.

In this way, if air leakage occurs in the air introduction passage 17 or if the passages 15a, 1 of the fuel injection valve 10
5b is clogged with foreign matter, the pressure inside the air introduction passage 17 changes to atmospheric pressure, and the differential pressure
Since the value of Pa-Pm becomes significantly larger than normal, you can accurately know the abnormality of the assist air function by comparing the a・△P set on the map and the Pa-Pm actually detected. be able to.

[Effect of idea]

As explained above, when using the fuel injection device of the present invention, the electronic control device that controls the operation of the engine is programmed so that the difference between the pressure in the intake passage and the pressure in the air introduction passage is greater than a preset value. We have added an abnormality detection function that determines that the air assist mechanism is abnormal when this occurs. If an abnormality occurs, the driver can immediately recognize the abnormality and take appropriate measures.

As a result, it is possible to prevent the piston from seizing up due to foreign matter that enters the air introduction passage due to air leakage, and to suppress variations in the air-fuel ratio between cylinders, which may be caused by poor control of the air-fuel ratio.
Increases in HC and torque fluctuations can also be prevented. Further, since clogging of the air jetting portion of the fuel injection valve is also prevented, deterioration of combustion is prevented in the same way as described above, and the function of the assist air mechanism can be fully demonstrated.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram of a fuel injection device according to an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of the fuel injection valve in FIG. 1, and FIG. 3 is a map of the electronic control device in FIG. 1. 4 is a flow diagram of the apparatus of FIG. 1. 5...Intake passage, 10...Fuel injection valve, 17...
...Air introduction passage, 19...First pressure sensor, 2
0...Second pressure sensor, 21...Electronic control unit, NE...Engine speed, Q...Intake air amount, Pa...Pressure in the air introduction passage, Pm...Pressure in the intake passage.

Claims (1)

[Scope of utility model registration request] In a fuel injection device for an internal combustion engine that promotes atomization of fuel by colliding assist air with injected fuel, an intake passage that leads intake air to a combustion chamber of the engine includes a first inlet passage that detects the pressure in the intake passage. A pressure sensor is provided in the air introduction passage connected to the intake passage and guides assist air to the fuel injection valve, and a second pressure sensor for detecting the pressure in the air introduction passage is provided, and the first pressure sensor and A second pressure sensor is connected to an electronic control unit that controls engine motion, and when the difference between the pressure in the intake passage and the pressure in the air introduction passage becomes larger than a preset value, an air assist A fuel injection device characterized by having an abnormality determination function for determining an abnormality in a mechanism.