JPS6039527A - Smoke detecting device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To maintain detecting accuracy, and also to detect detecting impossibility by correcting the result of detection of a smoke density based on the result of detection of the smoke density in case when supply of fuel to an engine has been stopped. CONSTITUTION:The light emitted by a light emitting element 38 of a projecting part 37 transmits through the inside of an exhaust passage 23a, is made incident on a photodetector 41, and a detecting signal VA corresponding to a smoke density in the course of exhaust is outputted from a detecting circuit 50. Compressed air from an air pump 44 is led into hollow tubes 39, 42, and adhesion of smoke to the light emitting element 38 and the photodetector 41 is prevented. On the other hand, a discriminating circuit 52 outputs a discriminating signal SB when a supply stop signal SA is inputted continuously for a prescribed time from a fuel supply stop detecting circuit 51, and an output holding circuit 53 holds the detecting signal VA. Also, a calibrating circuit 54 detects a variation quantity with respect to an initial value of a reference signal VB, calibrates the detecting signal VA in accordance with the result of this calculation, and outputs it as a smoke detecting signal VC.

Description

TECHNICAL FIELD The present invention relates to a smoke detection device for optically detecting smoke concentration in exhaust gas of an internal combustion engine.

In general, in internal combustion engines, especially diesel engines, the amount of smoke (carbon particles) generated tends to increase as the amount of fuel injection increases when the engine is under high load. This is an important issue.

Therefore, the present applicant first proposed a smoke restriction device that optically detects the smoke concentration in engine exhaust and corrects the fuel injection amount and injection timing based on the detection result (Japanese Patent Laid-Open No. 56-104124 (see publication).

The smoke detection device in this smoke restriction device is
To explain with reference to the figure, light from a light source 2 is focused into an exhaust passage 1 of an engine by a lens 3, and then is emitted in a direction across the exhaust passage 1 through a transparent window 4. The light emitted into the interior is collected by a lens 7.8 as transmitted light and scattered light through a transparent window 5 facing the transparent window 4 and a transparent window 6 not facing the transparent window 4, and then sent to a light receiving element 9. 10 receives light and performs photoelectric conversion, and the outputs of these light receiving elements 9 and 10 are compared by a differential amplifier 11, and the comparison result is output as a detection signal.

The transparent windows 4, 5, 6 are provided to prevent smoke from adhering to the light source 2 and the light receiving elements 9, 10.

According to this smoke detection device, when the amount of smoke in the exhaust passage 1 increases, the amount of transmitted light that passes through the exhaust passage 1 from the transparent window 4 and enters the directly facing transparent window 5 decreases. On the other hand, when the amount of scattered light due to smoke particles in the exhaust passage 1 increases, the amount of scattered light entering the transparent window 6 increases, and when the amount of smoke decreases, the amount of transmitted light increases, but the amount of scattered light increases. decreases.

Since the amount of transmitted light and the amount of scattered light change in accordance with the amount of smoke, the outputs of the two light receiving elements S and 10 change accordingly, and a detection signal corresponding to the amount of smoke is output from the differential amplifier 11. .

However, in such conventional smoke detection devices, if smoke in the exhaust gas adheres to the transparent windows for light emission and light reception facing the exhaust passage, the amount of light passing through each transparent window changes, making it difficult to accurately detect the smoke. If the amount of smoke cannot be detected and the amount of attached smoke increases, there will be an inconvenience that the amount of smoke cannot be detected.

In addition, for smoke detection devices that do not have a transparent window,
Smoke adheres directly to the light source and light receiving element, causing a similar problem.

This invention has been made in view of the above points, and is capable of maintaining detection accuracy when using a smoke detection device that optically detects smoke density as described above, and also detects undetectable cases. The purpose is to make it possible.

Therefore, the smoke detection device for an internal combustion engine according to the present invention detects that the supply of fuel to the engine is stopped, and retains the detection result of the smoke concentration when this detection result satisfies a predetermined condition. By doing so, it is possible to correct the smoke density detection result based on the held detection result.

Embodiments of the present invention will now be described with reference to FIG. 2 and subsequent figures of the accompanying drawings.

FIG. 2 is a schematic configuration diagram showing an example of a smoke restriction device as an internal combustion engine control device equipped with a smoke detection device embodying the present invention.

In the figure, an intake pipe 22 and an exhaust pipe 23 are connected to a swirl chamber type diesel engine 21, and an injection valve 25 for injecting fuel into a swirl chamber 24 is attached.

This injection valve 25 is connected to a fuel tank 26 and a filter 27 .
The fuel is injected through the fuel injection pump 28 and the control valve device 2.

The control valve device 29 includes, for example, a high-pressure fuel passage that transfers high-pressure fuel supplied from the fuel injection pump 28 to the injection valve 25, a fuel return passage that communicates this high-pressure fuel passage with the fuel tank 26, and this fuel return passage. The solenoid valve is provided with a solenoid valve that opens and closes, and by controlling the solenoid valve to open and close the fuel return passage, the supply tray of high-pressure fuel from the fuel injection pump 28 to the injection valve 25 can be controlled.

The control circuit 30 inputs the rotation angle signal from the crank angle sensor 31, the smoke detection signal from the smoke detection device 32, the accelerator pedal opening signal (not shown), etc., and determines the fuel injection amount and injection timing based on these. It is calculated and corrected, and the solenoid valve of the control valve device 29 is controlled based on the result.

Next, the configuration of the smoke detection device 32 will be explained.

FIG. 6 is a configuration diagram showing an example of a smoke detection device embodying the present invention.

In the figure, a passage (exhaust passage) 23 in the exhaust pipe 2'5
, a light emitting unit 37 that emits light to a light emitting element 38 consisting of a light emitting diode (LED) that generates light, holds this light emitting element 38, and exhausts the light from the light emitting element 38 into the exhaust passage 23a. It consists of a hollow tube attached to the exhaust pipe 23, forming an optical passage 39a introduced in a direction across the passage 23a, and an air introduction passage 39b communicating with the light emitting element 38 side of the optical passage 39a.

On the other hand, a light receiving section 40 receives the light emitted from the light projecting section 37.
A light receiving element 41 consisting of a photodiode that receives light and outputs a signal according to the amount of received light, and a light receiving element 41 that holds this light receiving element 41 and introduces light from the light projecting section 37 into the light receiving element 41. Passage 42. The air introduction passage 42b is formed to communicate with the light receiving element 41 side of the optical passage 42a, and a hollow tube 42 extends several times into the exhaust pipe 23.

Compressed air generated by the air pump 44 driven by the rotational force of the engine 210 in FIG. Introduction passage:! It is introduced via an air pipe 45 forming an air passage connected to S9b, 42b.

Although not shown, the detection circuit 50 includes the light emitting element 38
and a power supply circuit that supplies power to the light receiving element 41; and a power supply circuit that supplies power to the light receiving element 41;
It consists of an amplifier and the like that outputs a detection signal VA which is an amplified output of .

The fuel supply stop detection circuit 51 receives an engine speed signal S, for example.
1 and the accelerator depression angle signal S2.

By determining whether or not the accelerator depression angle has reached approximately 0 degrees at a high rotational speed, it is detected that fuel is not being supplied to the engine, and at this time a supply stop signal SA is output.

Note that the fuel supply stop detection circuit 51 may detect the fuel supply stop by detecting, for example, that the engine has stopped.

In addition, by detecting the lift of the injection valve needle valve,
Alternatively, this may be done by detecting the fuel injection pressure.

The determination circuit 52 detects the condition that when the supply stop signal SA from the fuel supply stop detection circuit 51 is continuously input for a predetermined period of time, that is, the state in which fuel is not supplied to the predetermined engine continues for a predetermined period of time. When the condition is satisfied, a discrimination signal SR is output.

The output holding circuit 53 receives the discrimination signal sn from the discrimination circuit 52.
The detection signal VA inputted from the detection circuit 50 when the detection signal VA is input is held, and the held detection signal VA is outputted as the reference signal VB.

The calibration circuit 54 inputs the detection signal VA from the detection circuit 50 and the reference signal VB from the output holding circuit 53, calibrates the detection signal VA based on the reference signal vn, and uses this calibration result as the smoke detection signal VC. , control circuit 3 in FIG.
Output to 0.

Note that these fuel supply stop detection circuits 512 and discrimination circuits 5
2. The output holding circuit 53 and the calibration circuit 54 are, for example, the second
By configuring the control circuit 30 shown in the figure with a microcomputer, it can also be configured as a part of the control circuit 30.

Next, the operation of this embodiment configured as described above will be explained.

First, the light emitting element of the light projecting section 37! The light emitted at +8 passes through the optical path 39. of the hollow tube 39. The gas is introduced into the exhaust passage 23a and ejected.

Then, this emitted light passes through the exhaust passage 23a, enters the hollow tube 42 of the light receiving section 40, and enters the optical passage 42. The light passes through the light receiving element 41 and enters the light receiving element 41 .

Accordingly, the light receiving element 41 outputs a voltage signal corresponding to the amount of received light to the detection circuit 50, and the detection circuit 50 outputs a detection signal VA.

In this case, the amount of light transmitted through the exhaust passage 23a decreases as the amount of smoke increases, and increases as the amount of smoke decreases, depending on the amount of smoke in the exhaust as described above, so that the output from the light receiving element 41 varies depending on the amount of smoke in the exhaust gas, and therefore the detection circuit 50 outputs a detection signal VA that corresponds to the smoke concentration in the exhaust gas.

In this smoke detection device, compressed air from the air pump 44 passes through the hollow tube 3E through the air passage 45.
1, 42 air introduction passage 3 days.

42b, the light is introduced into the light emitting element 38 and light receiving element 41 side of the optical paths 39a' and 42a.

Thereby, each optical path 39a, 4 of the hollow tube 3B, 42
2a, an air flow is generated in the direction of flowing into the exhaust passage 23a, so that the exhaust gas in the exhaust passage 23a flows through each of the optical passages 3B, 42. This prevents smoke from flowing into the interior and adhering to the light emitting element 38 and the light receiving element 41, allowing accurate smoke concentration detection over a long period of time.

On the other hand, when the fuel supply stop detection circuit 51 detects that fuel is not being supplied to the engine, it outputs a supply stop signal SA, and when the discrimination circuit 52 detects that the fuel supply stop signal SA is continuously input for a predetermined period of time, the fuel supply stop detection circuit 51 outputs a supply stop signal SA. A discrimination signal SR is output.

Thereby, the output holding circuit 53 holds the detection signal VA from the detection circuit 5o when the discrimination signal SB is input.

In other words, when fuel is not supplied to the engine for a specified period of time, it means that the engine is not burning fuel, and the exhaust gas at this time becomes almost the same as the atmosphere, and there is smoke in the exhaust. I will not do it.

Therefore, the output holding circuit 53 holds the detection signal VA when there is no smoke in the exhaust gas.

Therefore, the calibration circuit 54 stores, for example, the initial value of the reference signal VB, which is the detection signal VA held by the output holding circuit 53, calculates the amount of change from the initial value of the reference signal SH thereafter, and uses this calculation result as a reference signal. Accordingly, the detection signal VA of the detection circuit 50
is calibrated (corrected) and output as a smoke detection signal VC.

As a result, the smoke detection signal vc output from the calibration circuit 54 is the one obtained by correcting the detection signal VA from the detection circuit 50 in accordance with changes in light amount due to smoke adhesion on the light emitting element 38 and the light receiving element 41. , it becomes a signal that accurately indicates the amount of smoke.

FIG. 4 is a block diagram similar to FIG. 6 showing another embodiment of the present invention. In the following, only the points different from FIG. 3 will be explained.

In the figure, a comparator 56 inputs and compares the reference signal VB and limit value signal VR from the output holding circuit 53,
When VB>VR, the output is set to high level (H)
”

It is assumed that the reference signal VB (detection signal VA) from the output holding circuit 53 increases as the amount of light received by the light receiving element 41 decreases.

When the output of the comparator S6 becomes H'', the holding circuit 57 holds that state until a reset signal (not shown) is input, and during that time a warning light 58 consisting of a light emitting diode or the like is turned on.
lights up.

With this configuration, the value of the limit value signal VR input to the comparator on the 5th day is set to the reference signal V when the smoke amount cannot be detected due to dirt on the light emitting element 38 or the light receiving element 41.
By setting the value to B, the warning light 58 lights up when detection becomes impossible.

This allows users, service personnel, and the like to know when to clean or replace the light-emitting element or light-receiving element.

Note that the structure of the light emitting part that emits light into the exhaust passage of the smoke detection device and the light receiving part that receives the emitted light is not limited to that of the above embodiment, but may be, for example, as shown in FIG. Of course, it may be.

As described above, according to the present invention, it is possible to maintain the detection accuracy of an optical smoke detection device, and it is also possible to detect an undetectable state.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a conventional smoke detection device, FIG. 2 is a configuration diagram showing an example of a smoke restriction device equipped with a smoke detection device embodying the present invention, and FIG. FIG. 4 is a block diagram showing another embodiment of the present invention. 21...Diesel engine 2'5...Exhaust pipe 23a
...Exhaust passage 30...Control circuit 32...Smoke detection device 38...Light emitting element 41...Light receiving element 50...Detection circuit 51...Fuel supply stop detection circuit

Claims (1)

[Claims] 1. A smoke detection device that optically detects the smoke concentration in the exhaust gas of an internal combustion engine, which includes a fuel supply stop detection means for detecting that fuel is not being supplied to the engine, and a detection result of the fuel supply stop detection means. A smoke detection device for an internal combustion engine, comprising: a determining means for determining whether a predetermined condition is satisfied; and a retaining means for retaining the smoke concentration detection result according to the determination result of the determining means. .