JPH0194237A - Apparatus for detecting combustion of engine - Google Patents

Abstract

PURPOSE:To effectively prevent the adhesion of carbon to an optical fiber and to enhance the detection accuracy of a combustion state, by detecting the carbon adhesion amount to the lighting part of the optical fiber in a combustion chamber. CONSTITUTION:In order to detect the combustion light in a combustion chamber 3, the lighting part 20 of the side end part of the combustion chamber 3 of an optical fiber 21 is provided so as to be directly faced to the interior of the combustion chamber 3. The light signal introduced into a photoelectric converter 22 through the optical fiber 21 is converted to an electric signal showing the intensity and frequency (color) of the light signal to be inputted to a control unit 25 (ECU). When a carbon adhesion amount reaches a predetermined value or more, for example, the air/fuel ratio of a gaseous mixture is made leaner than that at a usual time by the control of the ECU 25 to make O2 excessive and the adhered carbon is burnt or combustion temp. is raised to burn the adhered carbon to remove said carbon from the optical fiber. By this method, the obstruction of the blocking of combustion light by adhered carbon is prevented and the enhancement of combustion state detection accuracy is achieved.

Description

Detailed Description of the Invention "Field of Application in Industry-1-" The present invention relates to an engine combustion detection device that detects the combustion state of the engine by blocking combustion light detected by an optical fiber. be.

[Prior Art] Engines that detect the combustion state of the air-fuel mixture in the combustion chamber and perform predetermined controls such as air-fuel ratio control and ignition timing control based on the combustion state are well known. As the state detection means, for example, one that detects the combustion state based on the combustion pressure in the combustion chamber (Utility Model Application No. 59-1)
65943), or one in which the combustion state is detected based on the vibration state of the printer has been proposed. However, these conventional sensors have problems such as low durability of the combustion pressure sensor or vibration sensor, and it is not possible to fully understand the combustion state only from the combustion pressure or cylinder vibration state.
There was a problem that highly accurate engine control could not be performed.

Therefore, the combustion light generated when the air-fuel mixture burns in the combustion chamber more accurately reflects the combustion state of the air-fuel mixture. For example, by analyzing the intensity, frequency, etc. of the combustion light, the presence or absence of knocking or misfire can be determined. Focusing on the fact that air-fuel ratio, etc. can be detected, we installed an optical fiber directly facing the combustion chamber, and based on the optical signal from this optical fiber, we can detect the ignition timing, combustion pressure, and knocking of the air-fuel mixture. Or detect the presence or absence of misfires, combustion conditions such as air-fuel ratio, etc., and perform predetermined engine control based on these? A strained version is proposed.

However, in this conventional method, the carphone generated from incompletely burned fuel in the combustion chamber lands on the lighting section at the tip of the optical fiber, so the optical signal is not input to the combustion state detection means through the optical fiber. 1) The amount of fuel is reduced by the amount blocked by the carbon, and there is a problem that the detection accuracy of the combustion state is reduced.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems of the conventional art. An object of the present invention is to provide a combustion detection device for an engine that can effectively prevent carbon from sticking to the engine and improve the accuracy of detecting combustion conditions.

[Structure 1 of the Invention] In order to achieve the object set forth in item 1, the present invention provides an optical fiber disposed facing directly into a combustion chamber, and a combustion state detection means for detecting a combustion state based on an optical signal from the optical fiber. an engine equipped with a carbon (Qj) adhesion detection means for detecting the amount of carbon adhesion to the optical fiber; To provide a combustion detection device for an engine, characterized in that it is provided with a combustion state changing means for temporarily changing the combustion state of the engine so as to reduce carbon attached to an optical fiber when this occurs.

[Effects of the Invention] According to the present invention, when the carbon adhesion amount detecting means detects the carbon adhesion on the lighting part of the optical fiber in the combustion chamber, and when the carbon adhesion amount becomes less than a predetermined value, the combustion Therefore, the state changing means 7, for example, makes the air-fuel ratio (A/F) of the air-fuel mixture leaner than normal.
2 Burning the attached carbon as excess, or
By performing high-load operation, the combustion temperature is raised to burn off the adhering carbon, and the adhering carbon is removed from the optical fiber. This interference with the transmission of combustion light to the combustion state detecting means is effectively prevented, and the accuracy of detecting the combustion state can be improved.

"Example" Examples of the present invention will be specifically described below.

<First Example> The following is the lighting part of the optical fiber? A first embodiment of the present invention will be described in which the attached carbon is burned and removed by atomization of the intake air.

As shown in FIG. 1, the engine E sucks intake air into the combustion chamber 3 from the intake boat 2 when the intake valve 1 is opened.
The basic configuration is such that this intake air is compressed by a piston 4, ignited and combusted by a spark plug 5, and the combustion gas is discharged to an exhaust passage 8 via an exhaust boat 7 when an exhaust valve -4=6 is opened. ing.

In order to supply intake air to the combustion chamber 3, an intake passage 11 communicating with the intake boat 2 is provided.
A throttle valve 12 that opens and closes in conjunction with an accelerator pedal (not shown) and an intake negative pressure sensor 13 that detects intake negative pressure are installed in order from the first stream, and an intake boat 2. An injector 14 is disposed nearby with its injection port tilted toward the downstream side.

Further, a high voltage secondary current induced in the secondary coil of the ignition coil 16 by the primary current which is intermittent at predetermined timings by the igniter 15 is supplied to the spark plug 5 via the distributor I7. This secondary current causes the ignition plug 5 to generate a spark and ignite the air-fuel mixture. The distributor 17 is rotationally driven in synchronization with a crankshaft (not shown), and the crank angle is detected by a crank angle sensor 18 provided within the distributor 1f.

By the way, in order to detect combustion light in the combustion chamber 3, an optical fiber 21 is installed with its lighting section 20 at the end on the side of the combustion chamber 3 facing directly into the combustion chamber 3, and this optical fiber 2++
-1 It is embedded in the center of the spark plug 5 so as to extend in the axial direction. A photoelectric converter 22 is connected to the other end of this optical fiber 21, and the optical fiber 2I is passed through 1. The optical signal introduced into the photoelectric converter 22 is here converted into an electrical signal representing the intensity and frequency (color) of the optical signal. This electrical signal is input to a control unit 25 (ECU) composed of a microcomputer.

As shown in FIG. 7, the optical fiber 21 is embedded in the ground electrode 23, and the ground electrode 23 serves as a heat point.
By arranging the light-collecting portion 20 of the optical fiber 21 at the bent portion of the center electrode 24, the amount of carbon deposited can be reduced compared to a conventional structure in which the optical fiber 2I is embedded in the center electrode 24.

As shown functionally in FIG. 2, the control unit 25 receives the photoelectric signal outputted from the photoelectric converter 22 and the crank angle signal outputted from the crank angle sensor 18, and controls each combustion stroke. Peak bold circuit 2 that detects the peak value of the photoelectric signal and the maximum intensity of the combustion light
6, also receives a photoelectric signal and a crank angle signal (J is the peak value generation timing of the photoelectric signal in each combustion stroke,
The peak timing detection circuit 27 detects the timing at which the combustion light intensity reaches its maximum, the intake negative pressure signal output from the intake negative pressure sensor 13, and the photoelectric signal peak value output from the peak hold circuit 26. An A/D converter 28 performs analog-to-dental conversion of the ignition timing and fuel injection pulse width using the intake negative pressure signal, combustion light intensity peak value signal, peak timing signal, and crank angle signal as input information. a CPU 29; a first timer 31 that adjusts the output timing of the ignition signal to the igniter I5;
It is comprised of a second timer 32 that adjusts the output timing of the pulse width signal to the injector I4, and a drive circuit 33 that applies a drive current to the injector 14.

The control method by the control unit 25 will be explained below. The control routine by the control unit 25 consists of a pack gran trusing, which is continuously and repeatedly executed regardless of the crank angle, as shown in the flowchart of FIG. (TDC) Interrupt the background routine once every time it reaches the position TD
It consists of a C interrupt routine.

The background routine control will be explained below according to flowchart 1 shown in FIG.

When the control is started, the intake negative pressure Pm is read in step S1.

Next, in step S2, the basic fuel injection pulse width T B of the injector 14 and the basic ignition timing 1g corresponding to the operating state of the engine E are calculated. Engine E operating status @
(J It is expressed by the intake negative pressure Pm and the engine speed Ne, and the engine speed Ne is calculated in step S2+ of the TDC interrupt interrupt-8 routine (see Fig. 4), which will be explained later. The basic fuel injection pulse width TB and the ignition timing 1g are calculated based on the intake negative pressure Pm, respectively.
and engine speed Ne as parameters and stored in the control unit 25, and the momentary intake negative pressure Pm and engine speed Ne
The fuel injection basic pulse width TB and basic ignition timing 1g corresponding to the above are read from each map.

In steps 83 to S4, it is determined whether the operating state of the engine E is in a feedback region where the fuel injection amount (air-fuel ratio) is feedback-controlled with the stoichiometric air-fuel ratio (λ-1) as the target value, or whether the air-fuel ratio is controlled in order to increase the output. It is determined whether the engine is in an enriched region where the air-fuel ratio is richer than the stoichiometric air-fuel ratio. In this embodiment, the region where the intake negative pressure Pm is higher than the predetermined engine 1 Rusoti judgment pressure Per (the pressure is high) and the region where the engine speed Ne is higher than the predetermined enrichment judgment rotation speed Ner are defined as the En1 Lusochi region. ).

As a result of the comparison in step 83 ~ S/I, if Pm≦Per (NO), if Ne≦Ner (NO),
Since the operating state of the engine E is in the feedback region, the control proceeds to the feedback routine of steps 85 to s7. On the other hand, whether Pm>Per (YES),
Or, if Ne>Ner (YES), engine E
Since the operating state is in the J edge region, control proceeds to step 88 to the SIO edge routine.

The feedback routine will be explained below.

In step S5, the lighting section 20 of the optical fiber 21 is
Lean conversion counter Cc for determining whether or not to perform intake air concentration in order to burn the car phone that has arrived.
is compared to see if it is 0. Lean counter Cc
As will be explained later, the count value is set in the TDC interrupt routine, and if lean conversion is not required for carbon combustion, the count value will be 07; on the other hand, if lean conversion is required ( J, the count number should be a predetermined positive value.As a result of the comparison, if Cc=O, (Y
ES), Since almost no carphone f=J is attached to the lighting section 20 of the optical fiber 2I, there is no need for lean conversion to burn carbon, and normal feedback control of the air-fuel ratio is performed. The control then proceeds to step S7.

In step S7, the air-fuel ratio? 1 is assigned to the ili positive coefficient Caf. The air-fuel ratio correction coefficient Caf is used to correct the fuel injection basic pulse width TB calculated in step S2, and the actual fuel injection pulse width T is calculated by the following equation.

T=TB-Car In this step, Caf=], so T=T
B, and normal air-fuel ratio feedback control is performed with the stoichiometric air-fuel ratio (λ-1) as the target value.

After this, control returns to step S1.

On the other hand, as a result of the comparison in step S5, if Cc≠O (No), carbon is attached to the lighting section 20 of the optical fiber 21, so control is performed to make the intake air lean and burn the carbon. is advanced to step S6. In step S6, 0.9 is substituted into (J, air-fuel ratio Mj positive coefficient Caf. Therefore, the actual fuel injection pulse width 1゛ is T = 0.9 TB, and T (J is 90% of normal feedback control. Therefore, the intake air is full, and when the air-fuel mixture is combusted, there is an excess of 0.0%, so the carbon attached to the lighting section 20 of the optical fiber 21 is naturally combusted by the high heat in the surroundings.After this, the control goes to step S11. I'm going back.

The engagement routine in steps S8 to S]0 will be described below.

In step S8, it is compared whether the lean counter Cc is O or not. As a result of the comparison, if Cc=O (Y
ES), there is almost no carbon in the lighting section 20 of the optical fiber 21 (-1), and there is no need to make the intake lean, so the control proceeds to step S9 to perform normal enrichment operation. In S9, 12 is substituted into the air-fuel ratio correction coefficient Caf.As a result, the actual fuel injection pulse width T is 12 times the fuel injection basic pulse width TB, and enrichment operation is performed, and the output of the engine E is increased. After this,
Control returns to step S1.

On the other hand, as a result of the comparison in step S8, if Cc≠0 (NO), carbon is attached to the lighting section 20 of the optical fiber 2I, so in order to burn this carbon,
In step SIO, the intake air is made leaner than during normal engine operation. That is, the air-fuel ratio correction coefficient Caf1.
:l is substituted, and the fuel injection amount is reduced compared to the normal engine operation using Car-1 and Car-2, and the intake air is unified.
The carbon that has arrived will burn. After this, the control goes to step S
Return to 1.

Hereinafter, according to the flowchart shown in Fig. 4, T D
C interrupt routine control will be explained.

When the crank angle reaches the intake stroke -1 - dead center (TDC) position, the control is started, and in step S21, the interrupt period T-1 is reached.
The ennon rotational speed Ne is calculated from the following equation.

Ne=(2/I()・60 (r, p, m,) Note that the interrupt period 1-1 (seconds) is the current interrupt time (TI)C
time) and the moe interruption time.

Next, in step S22, the combustion light peak timing Pθ at which the combustion light intensity becomes maximum is read.

In step S23, the combustion light peak timing P
It is compared whether θ is faster than or later than a predetermined time POo determined according to the operating state of Ennon E, or whether it is the same as 1. As a result of the comparison, ■] If θ<PGo (earlier than the predetermined timing), the ignition timing is advanced too much than the appropriate value, so in order to correct this, step S24 is performed.
(The ignition timing correction value 0 is inflated by the predetermined value Or)・
(retarded), the process proceeds to step 326. P.O.
> If PO6 (later than the predetermined timing), the ignition timing is too retarded than the appropriate value, so in order to correct this, the ignition timing correction value θ is set to the predetermined value Ca (J decrement) in step S25. (Advanced), the process proceeds to step S26. If it is PO-POo, the ignition timing is maintained at an appropriate value, so the process proceeds to step 826 without changing the ignition timing correction value θ. .

In step S26, the following equation? From this, the ignition timing Tg is calculated, and when the ignition timing Tg is reached, an ignition signal is output to the igniter I5.

Tg-Ig-θ Next, in step S27, the peak value lop of the combustion light signal is read, and then in step 928, a comparison is made to see if ``1 Sop'' is smaller than a predetermined carbon adhesion determination slice level lc. When carbon adheres to the lighting part 20 of the optical fiber 2I, the optical fiber 2
Although the combustion light transmittance of I decreases, 1c is set to the combustion light peak intensity corresponding to the permissible limit of the amount of carbon I deposited.

As a result of the comparison, if lop<Ic (YES), the amount of carbon adhering to the lighting section 20 of the optical fiber 21 is greater than the allowable limit, so the lean counter Cc is set to a predetermined positive value in step S29. The value Nc is assigned. As described above, when the count number of the lean conversion counter Cc is a positive value, the intake air is leanened in order to burn the engine power. (As explained later, the lean counter Cc is TDC while lean is being executed.
Since it is decremented by 1 each time the interrupt routine is executed, Nc is used to determine the duration of one lean conversion. On the other hand, if Top≧Ic (
NO), there is no need to reset the lean counter Cc, so step S29 is not executed and step S30
? This will be skipped.

In step S30, it is compared whether the lean counter Cc is 0 or not. As a result of the comparison, if Caf0 is (
No), since the lean conversion is being executed, the lean conversion counter Cc is decremented by 1 by 1J in step S31, and the process proceeds to step S32. On the other hand, if Cc = 0, (Y
ES), since the lean process has not been carried out, step S31 is not executed and the process is skipped to step S32.

In step S32, the fuel injection pulse width T of the injector 14 is calculated by the following formula, and at a predetermined timing,
A drive current corresponding to the pulse width signal 1 is output to the injector 14, and fuel injection is performed.

T=TB-Caf At this point, the current TDC interrupt routine is ended, and when the next intake stroke reaches the second dead center, this TDC interrupt routine is repeatedly executed again.

Second Embodiment> In the first embodiment, the carbon that has arrived at the lighting section 20 of the optical fiber 21 is burnt by making the intake air lean and in an 02 excess state. Methods for removing (J, but not limited to,
For example, high load operation may be performed to increase the amount of carbon deposited, and the combustion temperature may be increased to burn the amount of carbon deposited. Below, in autotransmission vehicles,
In the second embodiment of the present invention, when carbon adheres to the lighting section 20 of the optical fiber 21, high-load operation is performed by shifting up, and the combustion temperature is increased to burn off the adhered carbon. Explain an example.

The system configuration of the engine E in the second embodiment is the same as that in the first embodiment shown in FIG. 1, and only the control method by the control unit 25 is different. Therefore, only the control method by the control unit 25 will be explained. .

The control routine by the control unit 25 includes the first
Like the embodiment, it is composed of a pack-crank routine and a TDC interrupt routine that are always executed.

The background routine control will be explained below according to the flowchart 1 shown in FIG.

In step S41, the intake negative pressure Pm is read, and in step 57I2, the intake negative pressure Pm and the engine rotation speed Ne are read.
The fuel injection pulse width T of the injector 14 is based on
n and ignition timing Tg are calculated. Incidentally, steps S4i to 84.2 of "1" are the same as steps S1 to S2 of the pack-and-crank routine of the first embodiment shown in FIG. 3, so a detailed explanation will be omitted.

In step S43, a shift position Sp is calculated from the throttle opening and vehicle speed. Note that a soft I/position detection switch may be provided to detect the soft position.

Next, in step S44, the shift-up counter Cc for determining whether to shift up and perform high-load operation in order to burn the carbon deposited on the lighting section 20 of the optical fiber 21 is 0. It is compared whether or not.

The above-mentioned shift up counter Cc corresponds to the lean counter Cc in the first embodiment, and when it is necessary to shift up in order to burn some carbon, the count value becomes a positive value, and when upshifting is not necessary, it takes a positive value. The count number becomes 0.

As a result of the comparison, if Cc=0 (YES), there is no need to shift up to burn the deposited carbon, so the shift position is not changed and the control returns to step S41.

=19- On the other hand, if the result of the comparison in step S44 is Cc≠0 (NO), a comparison is made in step S45 to see if the shift position sp is the highest speed position 4th speed. As a result of the comparison, S
If p='4 (YES), the shift amplifier cannot be used, so the software position is not changed and the control returns to step S4].

As a result of the comparison in step S45, if Sp≠4 (N
O) Since upshifting is possible, upshifting is performed in step S46. As a result, the torque ratio becomes smaller with respect to the vehicle speed, resulting in a torque shortage, so the driver depresses the accelerator pedal and the throttle valve 12 is opened wider than normal, resulting in high-load operation, which lowers the combustion temperature. - 471 to the lighting section 20 of the optical fiber 21
The car phone that lands will be burned. After this, control returns to step S41.

The flowchart shown in Figures 6(a) and (b) below)
The 'I' DC interrupt routine control will be explained according to the following. Steps 21 to T31 are respectively the same as steps S21 to S31 of the TDC interrupt routine of the first embodiment shown in FIG. The explanation will be omitted.

Hereinafter, only steps T32 to T3/l will be explained.

In step T32, a drive current corresponding to the fuel injection pulse width TR is output to the injector 14 at a predetermined timing, and fuel injection is performed.

In step T33, the transmission is switched according to the shift position Sp.

Next, in step T34, the vehicle speed is read, and the current T
DC interrupt routine control ends.

Note that the TDC interrupt routine is repeatedly executed every time the intake stroke reaches top dead center.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an engine equipped with a combustion detection device according to the present invention, and is common to the first embodiment and the second embodiment. FIG. 2 is a functionalized diagram of the engine control unit shown in FIG. 1. FIG. 3 and FIG. 4 respectively show the first embodiment of the present invention (
1 is a flowchart of pack ground routine control by the JRU control unit and TDC interrupt routine control. FIG. 5 and FIGS. 6(a) and 6(b) respectively show the flowchart of the pack ground routine control by the control unit in the second embodiment of the present invention) and 1' D C
This is a flowchart 1 of interrupt routine control. FIG. 7 is an explanatory elevational view of a spark plug in which the lighting part of the optical fiber is disposed at the bent part of the ground electrode where carbon is difficult to adhere to. E Ennon, 3... Combustion chamber, 5 Spark plaque, 12
Throttle valve, 14 Innoecta, 20... Lighting section, 2I... Optical fiber, 22 ・Photoelectric converter, 25
·control unit.

Claims (1)

[Claims] (1) An optical fiber installed facing directly into the combustion chamber,
An engine equipped with a combustion state detection means for detecting a combustion state based on an optical signal from the optical fiber, a carbon adhesion amount detection means for detecting an amount of carbon adhesion to the optical fiber, and a combustion state detection means for detecting a combustion state based on an optical signal from the optical fiber. Combustion state changing means is provided for temporarily changing the combustion state of the engine so as to reduce the amount of carbon adhering to the optical fiber when the detected amount of carbon adhesion to the optical fiber exceeds a predetermined value. Characteristic engine combustion detection device.