CN1179826A - Misfire detection dependent on intake air charge fluctuations - Google Patents
Misfire detection dependent on intake air charge fluctuations Download PDFInfo
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- CN1179826A CN1179826A CN 96192819 CN96192819A CN1179826A CN 1179826 A CN1179826 A CN 1179826A CN 96192819 CN96192819 CN 96192819 CN 96192819 A CN96192819 A CN 96192819A CN 1179826 A CN1179826 A CN 1179826A
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Abstract
A misfire detection system and method measures fluctuations of air charge ingested into an engine 303 preferably as fluctuations of the engine's intake air pressure or as fluctuations of the mass air flow. A misfire indication 337 is provided dependent on a behavior of the fluctuations of air charge. Preferably, to eliminate errors associated with engine transient operating conditions, such as acceleration, the fluctuations of air charge are differentiated (325) before a misfire detection mechanism (333) is used to determine misfire behavior.
Description
The present invention relates to the field of the detection of circulating engine interior misfire, or rather, relate to a kind of a kind of method and corresponding device thereof that is used for being determined at circulating engine misfire, this method realizes by the air inflow fluctuation that causes owing to the engine loading variation relevant with the internal-combustion engine ignition bad condition is detected judgement.
The modern engine misfire detection system that is used for circulating engine is carried out the misfire detection, so that measure burn incompletely.Misfire causes power attenuation, with unburned fuel impouring catalysis type converter, these factors will shorten its life-span, and radiate the objectionable impurities of the higher extent of injury.The strict demand of current rule of management detects whether misfire has taken place.
A kind of method of current misfire detection system is to adopt the deviation with expection crankshaft speed or acceleration is detected.A lot of these type systematics are effectively but unnecessarily complicated.In order to satisfy rules, these systems must be according to very high data rate detection engine crankshaft position data.This just need propose more to be strict with to relevant signal processing circuit, makes it complicated.In addition, in order to implement this method effectively, must engine crankshaft position be detected with quite high resolution.In order can engine crankshaft position to be detected, require great amount of investment aspect the engine mechanical part processing with very high resolution.
Another kind of scheme is the deviation of monitoring discharge pressure, and analyzes by the harmonic component frequency spectrum of engine through the gas of its exhaust system discharge.Be a principal element serviceable life of sensor in these systems, because it is operated in harmful environment in the exhaust system.In addition, the degree of accuracy of this scheme depends basically on the characteristic of the connection medium in the exhaust system.Exhaust system comprises that one is connected to the exhaust manifold of gas outlet, is connected to the catalysis type converter, is connected to exhaust box, connects another gas outlet again.Because this structure, from engine running, the interference relevant with the noise source that comprises the engine that is coupled on the exhaust system and Vehicular vibration is responsive for non-in its configuration.The resonance of this connection medium may be superimposed to by on the harmonic component frequency spectrum from engine.In addition, because its volume is too big, the exhaust system effect is as a low-pass filter, and having reduced useful signal therefore influences measuring accuracy.In addition, change from heating or the cooling of travel-time of the sound of engine with exhaust system.In addition, the length of the sound transmission approach of each cylinder changes with each cylinder, because the length difference is led in the exhaust of exhaust manifold.The changeability of time delay this will cause when being opened by vent valve to it when detected.This variable-length that is connected to sensing device by each cylinder also may cause by the frequency spectrum phase shift from the harmonic component of engine.This causes that because of pressure wave reflection this reflection is because pressure pulse causes from the used different time quantum of sonic transducer that vent valve propagates into difference cylinder.
Needing to improve the method that is used for the engine misfire detection is to make it simple relatively, is not subjected to the influence of the inaccurate factor of prior art simultaneously as far as possible.
Fig. 1 is the system block diagrams of engine aspirating system;
Fig. 2 is the curve map that the air input of engine by air fluctuation is measured in expression;
Fig. 3 is a system block diagrams according to a preferred embodiment of the invention;
Fig. 4 is illustrated in the motor characteristic curve of measuring according to the air capacity fluctuation that sucks engine through after the signal Processing of removing hazardous noise.
Misfire detection system and method measurement enter the air capacity fluctuation of engine.These fluctuations can change according to admission pressure, air-mass flow changes or the amount of equivalence is measured.Formed the indicator signal of misfire according to the situation of these fluctuations.Best, in order to eliminate the relevant error of transient state duty (for example state of engine acceleration work) with engine, the fluctuation to air capacity before misfire testing agency measures this fluctuation is handled.
This novel scheme detects misfire by the fluctuation of measuring air inflow.The air-distributor pressure of engine is with engine crankshaft speed and introduce the inversely proportional mode of the quality of air capacity at the engine cycle of appointment and change.In the preferred embodiment, the air-distributor pressure signal is differentiated (differentiated), with the relevant signal of air capacity that obtains quickening and introducing with engine crankshaft.The signal of differential was handled to remove the noise spectrum component before measuring the misfire process.This method is attractive especially for the system that utilizes air-distributor pressure or mass flow sensor to carry out engine control, because need not other sensor.
Fig. 1 is the system block diagrams of engine aspirating system.Air 105 under the atmospheric pressure offers engine 101 by super charge system 103.Utilize choke block 107 that the air under the atmospheric pressure 105 is regulated the super charge system 103 that enters.The pressure of the air-flow 109 in super charge system 103 or mass rate depend on the pressure differential that is created between air 105 under the atmospheric pressure and the engine 101 in the super charge system 103.When engine operation, the pressure of air-flow 109 or quality basis are changed by the swabbing action that admission stroke produces of the cylinder of engine 101.The situation of swabbing action, that is the pressure of air-flow 109 or quality also depend on and get rid of the machine torque that each cylinder produced that is in beyond the intake process.Represent to enter the example of fluctuation of the air capacity of engine below in the mode of curve map.
Fig. 2 is the curve map of the measured air input of engine by air 200 of expression.When engine normally moved, air inflow 200 was by changing with the fluctuation mode shown in the label 201.When air inflow descended, waveform 200 was along reverse reduction.This reverse transformation shows inlet open, and corresponding cylinder is through the certain air capacity of gas admittance valve inspiration.Along with gas admittance valve cuts out, intake velocity slows down, and admission pressure increases, or MAF 200 descends.If produce the disturbance to the machine torque of engine that may be caused by the engine of misfire, the pressure of air inlet can change.And then when misfire took place, the gaseous mass that enters cylinder was compared with the cylinder of normal ignition and can be reduced.These two kinds of effects slightly raise the admission pressure relevant with the cylinder of misfire, shown in label 203.Subsequently, when engine was stablized and normally moved once more, pressure and mass rate turned back to their early stage numerical value, as using shown in the label 205.
In the preferred embodiment, to measure the described state variation of air inflow waveform 200, and analyze, the motor torque relevant with the cylinder of misfire with prediction changes.The frequency of the main signal of the output signal that described system produces depends on the frequency a kind of expression of each misfire process (promptly for) of misfire.Below, the introducing system calcspar.
Fig. 3 is overall system block diagrams, some aspect of the improvement project that expression is introduced here.Provide certain air inflow 303 by inlet manifold 305 to engine 301.
The bent axle 309 that engine speed sensor 307 monitorings link to each other with piston flywheel 311.These parts 307,309 and 311 produce the signal 313 of reflection engine rotation position.Engine rotation position signalling 313 is used to arrange the control procedure of controller 315.The part 307 of air inflow 303 is transported to pressure transducer 319.Best pressure transducer 319 is Motorola PRT (pressure resistance type transducer) pressure transducer.Web member 321 between inlet manifold relevant with rotation system 305 and pressure transducer 319 designs its geometric parameter, so that minimum (for example make hose diameter big and hose length is little) is reduced in issuable harmful resonance effect.
Preferably controller 315 is by constituting with Motorola 68332 microcontrollers.The Motorola68332 microcontroller is particularly suitable for current operation, because required air inflow and the engine location information of computing power that it has and processing adapts.Person skilled in the art will recognize that other equivalent microcontroller also can implement method for optimizing described here.In addition, controller 315 can be replaced the execution identical functions with analog or digital hardware.
Link 323-337 in the frame of controller 315 is the step by the signal Processing of microcode, and these steps are to programme according to the steering order in controller 315.At first treatment step 323, controller 315 depends on the reservation table that utilizes engine rotation position signalling 313 definite engine crankshaft positions to quote according to one, and the signal that is provided by pressure transducer 319 is carried out digitizing.In the preferred embodiment, this digitized signal is the air pressure signal.In addition, if utilize air mass flow sensor to replace pressure transducer 319, this signal can be the measuring-signal of MAF.Best, to the partial-air admission amount 317 of air inflow 303 once sampling when 18 ° of every rotations of engine crankshaft the time.The reservation table of this low relatively resolution obviously is superior to those prior art systems that needs high resolving power to measure.
Then, in treatment step 325,, handles admission pressure definite air inlet fluctuation signal according to being differentiated.This differentiating handled the influence of any transient state work (for example engine quickens and engine retard) that can eliminate engine.
Then, the air pressure fluctuation of differential is handled, to eliminate various noise sources.Before the situation of misfire can accurately be detected, must carry out this processing.Need remove by the caused fluctuation of normal engine torque.Having two independent operations to carry out sort signal handles.At first, handle the air pressure fluctuation of differential, to remove the spectrum component of mainly relevant high order with normal engine torque by a low-pass filter 327.
Then, handle by 329 pairs of air pressure fluctuations of a median filter, to remove the spectrum component of low order through the differential of low-pass filtering.The engine driving system disturbance that causes owing to not gentle other reason of road can be determined the feature of low order spectrum component.Then, produce air pressure fluctuation signal 331 through the differential of low pass-medium filtering.
Best, low pass and median filter are realized according at least a engine characteristics of selecting in the engine parameter group of being made up of engine speed, engine loading and engine temperature.The engine parameter of engine speed, engine loading and engine temperature is to utilize to measure at the routine techniques of link 341.
Then, representative is provided to comparer 333 through the air pressure fluctuation signal 331 of the differential of low pass-medium filtering.Comparer 333 will be compared with threshold value 335 through the air pressure fluctuation signal 331 of the differential of low pass-medium filtering, and when this through air pressure fluctuation signal 331 of the differential of low pass-medium filtering generation misfire detection signal 337 during above threshold value 335.Best, determine threshold value 335 according at least a engine characteristics of selecting in the engine parameter group of forming by engine speed, engine loading and the engine temperature in link 341, determined of more preceding introduction.
It should be noted that with itself can showing and be in and engine crankshaft other the relevant noise of operating mode in the spectral range of one-period that whenever rotates a circle and a half comprises: because the circulation moment of inertia, piston mass is uneven and each cylinder between the single order influence of the uneven caused bent axle moment of torsion of burning.All these situations may have a strong impact on the precision that misfire is determined method.Pattern is eliminated (pattern cancellation) link 339 can these undesirable conditions of filtering, exactly from through low pass-medium filtering and removed these undesirable conditions the air pressure fluctuation signal 331 of differential.By period 1 of engine crankshaft rotation to through low pass-medium filtering and air pressure fluctuation signal 331 samplings of differential provide first data point, the second round of engine crankshaft rotation to through low pass-medium filtering and air pressure fluctuation signal 331 samplings of differential second data point is provided, and period 3 of engine crankshaft rotation to through low pass-medium filtering and air pressure fluctuation signal 331 samplings of differential the 3rd data point is provided, can realize this specific character (curve) compensation by this data acquisition.Then, deduct the mean value of the first and the 3rd data point by second data point, can produce eliminate through pattern, through low pass-medium filtering and differentiate after obviously remove the air pressure fluctuation signal of single order influence.
In Fig. 4, represented to eliminate through pattern, through low pass-medium filtering and the air pressure fluctuation signal of differential.The a plurality of normal ignition combustion processes of first's 401 representatives, the combustion process of a plurality of misfires of second portion 403 representatives, wherein second portion is the misfire that forms for demonstration.Dotted line 405 representatives previously mentioned threshold value 331 (with diagramatic way) in Fig. 3.Should note, eliminate through pattern, through low pass-medium filtering, the misfire part 403 of the air pressure signal 332 of differential surpasses threshold value 405 significantly, and eliminate through pattern, through low pass-medium filtering, the normal ignition combustion parts 401 of the air pressure fluctuation signal 332 of differential surpasses threshold value 405 fairly obviously.This this difference through pattern air pressure fluctuation that eliminate, low pass-medium filtering, differential signal between normal ignition part 401 and misfire part 403 all is excellent in any high-precision test system (system for example described here).
Consult Fig. 3 again, eliminate through pattern, low pass-medium filtering, the air pressure fluctuation signal 332 of differential alternately is input to comparer 333 through selector switch 330.In this case, when this when pattern air pressure fluctuation that eliminate, low pass-medium filtering, differential signal 332 surpasses threshold value, can produce misfire detection signal 337.The duty of various engines is depended in the action of selector switch.
In a word, above by the agency of a kind of method for improvement of detecting misfire, this side Method can be implemented relatively simplely, this be because it does not need as the prior art in order to form one High accuracy is lighted a fire bad detection system and is needed high-resolution engine location code Design. Described Method can take full advantage of the advantage of existing sensor. This has not only eliminated and the high-resolution engine The complexity problem that position coder is relevant, but also eliminated because of the machinery unit of processing as hardware The cost that part brings and complexity problem. In addition, with take high-resolution engine location encoder as The misfire detection system on basis is compared, post processing link 325,327,329 and 339 Signal is processed bandwidth can be loose.
Claims (18)
1. misfire detection method that is used for engine comprises:
Measurement is drawn into the fluctuation of the air capacity of engine, and
The indicator signal of misfire is provided according to the fluctuation of measured air capacity.
2. misfire detection method according to claim 1, the step of wherein measuring the air capacity fluctuation that sucks engine comprises the step of the fluctuation of measuring the air pressure that sucks engine.
3. misfire detection method according to claim 2 also comprises step:
With the air pressure fluctuation signal transformation of measured suction engine is the air pressure fluctuation signal of differential; And
The step of misfire indicator signal wherein is provided, provides the misfire indicator signal according to the air pressure fluctuation of differential.
4. misfire detection method according to claim 3 also comprises step:
According at least a engine characteristics of selecting in the engine parameter combination of forming by engine speed, engine loading and engine temperature, to the air pressure fluctuation signal filtering of differential, and provide air pressure fluctuation signal in view of the above through the differential of filtering; And
The step of misfire indicator signal wherein is provided, provides the misfire indicator signal according to amplitude through the air pressure fluctuation signal of the differential of filtering.
5. misfire detection method according to claim 1, the step of wherein measuring the fluctuation of the air capacity that sucks engine comprise the step of measuring the gas mass flow fluctuation that is drawn into engine.
6. misfire detection method according to claim 5 also comprises step:
The measured fluctuation signal that is drawn into the MAF in the engine is transformed to the MAF fluctuation signal of differential; And
The step of misfire indicator signal wherein is provided, provides the misfire indicator signal according to the MAF fluctuation signal of differential.
7. misfire detection method according to claim 6 also comprises step:
According at least a engine characteristics of selecting in the engine parameter group of forming by engine speed, engine loading and engine temperature, to through the MAF fluctuation signal filtering of differential, and provide MAF fluctuation signal in view of the above through the differential of filtering; And
Wherein, provide the step of misfire indicator signal, provide the misfire indicator signal according to amplitude through the MAF fluctuation signal of the differential of filtering.
8. misfire detection method according to claim 1 also comprises step:
Measure the position of inlet manifold air damper; And
The step of misfire indicator signal wherein is provided, provides the misfire indicator signal according to the position of measured inlet manifold air damper.
9. misfire detection method according to claim 1 also comprises step:
According at least a engine characteristics of selecting in the engine parameter group of forming by engine speed, engine loading and engine temperature, establish the threshold value of differentiating misfire; And
Wherein, provide the step of misfire indicator signal, the misfire indicator signal is provided when the amplitude of the air capacity fluctuation deviation that sucks engine surpasses the misfire discrimination threshold of defined.
10. misfire detection method that is used for engine comprises:
Measure the engine crank angle position;
The measured value of the predetermined admission pressure that matches with measured engine crank angle position is provided;
The admission pressure measured value is differentiated, form the air inlet signal of differential; And
According to the air inlet signal of differential, provide the misfire indicator signal.
11. misfire detection method according to claim 10 also comprises step:
According at least a engine parameter of selecting in the engine parameter group of forming by engine speed, engine loading and engine temperature,, and provide air inlet signal in view of the above through the differential of filtering to the air inlet signal filtering of differentiating; And
Wherein, provide the step of misfire indicator signal, the air inlet signal according to through the differential of filtering provides the misfire indicator signal.
12. misfire detection method according to claim 10 also comprises step:
Measure the position of inlet manifold air damper, and
Wherein, provide the step of misfire indicator signal,, provide the misfire indicator signal according to the position of measured air damper.
13. misfire detection method according to claim 10 also comprises step:
According at least a engine characteristics of selecting in the engine parameter group of forming by engine speed, engine loading and engine temperature, establish the misfire discrimination threshold; And
The step of misfire indicator signal wherein is provided, provides the misfire indicator signal according to the misfire discrimination threshold of establishing.
14. a misfire detection system that is used for engine comprises:
Be coupled to the sensor on the engine, be used for the undulate quantity of the air capacity that sucks engine is measured; And
Signal processor is used for the amplitude according to the fluctuation of the air capacity that sucks engine, and the misfire indicator signal is provided.
15. misfire detection system according to claim 14, signal processor wherein comprises:
Differentiator is used to receive the fluctuation signal of the air capacity that sucks engine, in view of the above, provides the air capacity signal of differential; And
Comparer is used to receive the air capacity signal of differential, and provides the misfire indicator signal when the air capacity signal of differential surpasses a threshold value.
16. misfire detection system according to claim 14, wherein said signal processor comprises:
Differentiator is used to receive the air capacity fluctuation signal that is drawn into engine, and the air capacity signal of differential is provided in view of the above;
Low-pass filter is used to receive the air capacity signal of differential, and the air capacity signal through the differential of low-pass filtering is provided in view of the above;
Median filter is used to receive the air capacity signal through the differential of low-pass filtering, and the air capacity signal through the differential of intermediate value-low-pass filtering is provided in view of the above; And
Comparer is used to receive the air capacity signal through the differential of intermediate value-low-pass filtering, and when the air capacity signal through the differential of intermediate value-low-pass filtering surpasses the misfire discrimination threshold, provides the misfire indicator signal.
17. misfire detection system according to claim 14, misfire discrimination threshold wherein are to set up according to the measured value of at least a engine characteristics of selecting in the engine parameter combination of being made up of engine speed, engine loading and engine temperature; And
Comparer wherein when the amplitude through the air capacity signal of the differential of intermediate value-low-pass filtering surpasses the misfire discrimination threshold, provides the misfire indicator signal.
18. misfire detection system according to claim 16 comprises:
The pattern canceller is used to receive the air capacity signal through the differential of intermediate value-low-pass filtering, and provide in view of the above eliminate through pattern, through the air capacity signal of the differential of intermediate value-low-pass filtering; And
Wherein, comparer receives the air capacity signal of eliminating through pattern through the differential of intermediate value-low-pass filtering, and eliminates through pattern when this, when the air capacity signal of the differential of intermediate value-low-pass filtering surpasses threshold value, provides the misfire indicator signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 96192819 CN1179826A (en) | 1996-01-25 | 1996-12-13 | Misfire detection dependent on intake air charge fluctuations |
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| Application Number | Priority Date | Filing Date | Title |
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| US08/591,838 | 1996-01-25 | ||
| CN 96192819 CN1179826A (en) | 1996-01-25 | 1996-12-13 | Misfire detection dependent on intake air charge fluctuations |
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| CN1179826A true CN1179826A (en) | 1998-04-22 |
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| CN 96192819 Pending CN1179826A (en) | 1996-01-25 | 1996-12-13 | Misfire detection dependent on intake air charge fluctuations |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100441850C (en) * | 2003-08-06 | 2008-12-10 | 丰田自动车株式会社 | Control device and misfire determination method for internal combustion engine |
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- 1996-12-13 CN CN 96192819 patent/CN1179826A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100441850C (en) * | 2003-08-06 | 2008-12-10 | 丰田自动车株式会社 | Control device and misfire determination method for internal combustion engine |
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