Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L23/00—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid
  • G01L23/22—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines
  • G01L23/221—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines
  • G01L23/225—Devices or apparatus for measuring or indicating or recording rapid changes, such as oscillations, in the pressure of steam, gas, or liquid; Indicators for determining work or energy of steam, internal-combustion, or other fluid-pressure engines from the condition of the working fluid for detecting or indicating knocks in internal-combustion engines; Units comprising pressure-sensitive members combined with ignitors for firing internal-combustion engines for detecting or indicating knocks in internal combustion engines circuit arrangements therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P5/00—Advancing or retarding ignition; Control therefor
  • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
  • F02P5/145—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
  • F02P5/15—Digital data processing
  • F02P5/152—Digital data processing dependent on pinking
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
  • F02P5/00—Advancing or retarding ignition; Control therefor
  • F02P5/04—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions
  • F02P5/145—Advancing or retarding ignition; Control therefor automatically, as a function of the working conditions of the engine or vehicle or of the atmospheric conditions using electrical means
  • F02P5/15—Digital data processing
  • F02P5/152—Digital data processing dependent on pinking
  • F02P5/1521—Digital data processing dependent on pinking with particular means during a transient phase, e.g. starting, acceleration, deceleration, gear change
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the present invention relates generally to knock determination devices and ignition control systems including the same and particularly to such devices and systems that determine from a waveform of vibration of an internal combustion engine whether the engine knocks.
• Japanese Patent Laying-Open No. 2000-205096 discloses an internal combustion engine knock detection device provided for an internal combustion engine and capable of detecting knocking with high precision.
• the knock detection device disclosed in this document includes a knock detector detecting the internal combustion engine's mechanical vibration to output a knock signal, and a knock determiner determining whether the engine knocks from the knock detector's knock signal in accordance with a reference knock level obtained by a background level BG
• the knock determiner determines that the engine knocks if a vibration component calculated by subtracting mechanical vibration and electrical components from a peak value of a signal output from the knock detector is larger than the reference knock level, and if the vibration component is equal to or smaller than the reference knock level the knock determiner determines that the engine does not knock.
• the knock detection device described in this document can compare a vibration component corresponding to a peak value of a signal output from the knock determiner minus mechanical vibration and electrical noise components with a reference knock level obtained by removing mechanical vibration and electrical noise components to detect with high precision whether an internal combustion engine knocks or not.
• the knock detection device described in the above document is, however, disadvantageous in that if the knock detector outputs a signal having a peak large in value the device detects that the engine knocks, and when the engine does not knock and the knock detector nonetheless outputs a signal having a peak increased in value a decision that the engine knocks may erroneously be made.
• An object of the present invention is to provide a knock determination device capable of determining with high precision whether knocking occurs. Another object of the present invention is to provide an ignition control system capable of determining with high precision whether knocking occurs, and if so, reducing the knocking. Still another object of the present invention is to provide a knock determination device capable of reducing an erroneous decision that knocking does not occur despite that knocking occurs. Still another object of the present invention is to provide a knock determination device capable of objectively determining whether knocking occurs.
• the present knock determination device for an internal combustion engine includes: a crank angle detector detecting the internal combustion engine's crank angle; a waveform detector detecting a waveform of vibration of the internal combustion engine for a predetermined crank angle range; a storage previously storing a waveform of vibration of the internal combustion engine for the predetermined crank angle range; a corrector correcting the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when the internal combustion engine is in a predetermined driving condition; and a determiner determining whether the internal combustion engine knocks, as based on a result of comparing the detected waveform and the corrected waveform.
• a crank angle detector detects an internal combustion engine's crank angle and a waveform detector detects a waveform of vibration of the internal combustion engine for a predetermined crank angle range.
• a storage previously stores a waveform of vibration of the internal combustion engine for the predetermined crank angle range and a corrector corrects the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when the internal combustion engine is in a predetermined driving condition.
• a knock waveform model created for example in an experiment can be corrected as based a waveform of vibration detected when the engine does not knock, and the engine itself s mechanical vibration component can be contained in a waveform of vibration stored.
• the knock waveform model can be more approximate to a waveform of vibration of the engine caused when the engine knocks.
• the model and a detected waveform can be compared to determine whether the engine knocks.
• a crank angle for which vibration occurs can also be depended on to determine whether the engine knocks.
• the knock determination device can determine with high precision whether the engine knocks.
• the determiner determines that the internal combustion engine knocks when the detected waveform and the corrected waveform match within a predetermined range.
• the determiner determines that the internal combustion engine knocks when the detected waveform and the corrected waveform match within a predetermined range.
• a knock waveform model corresponding to a waveform of vibration caused when the engine knocks can previously be created for example in an experiment and stored and if for example a corrected version of this knock waveform model and a detected waveform provide a deviation within a reference value for each crank angle or such deviations' average falls within the reference value a decision can be made that the engine knocks.
• a crank angle for which vibration occurs can also be depended on to determine whether the engine knocks. As a result whether the engine knocks can be determined with high precision.
• the corrector corrects the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when fuel supplied to the internal combustion engine is interrupted.
• the corrector corrects the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when fuel supplied to the internal combustion engine is interrupted.
• a waveform of vibration detected will be that of mechanical vibration of the engine itself.
• This waveform of mechanical vibration of the engine itself can be used to correct a stored waveform of vibration to allow the stored waveform of vibration to contain the engine itself s mechanical vibration component.
• the stored waveform of vibration can thus be more approximate to a waveform of vibration of the engine caused when the engine knocks. As a result, whether the engine knocks can be determined with high precision.
• the corrector corrects the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when the internal combustion engine's output transitions.
• the determiner determines whether the internal combustion engine knocks, as based on a result of comparing the detected waveform and the corrected waveform.
• the corrector corrects the waveform of the vibration of the internal combustion engine stored in the storage, as based on a waveform of vibration of the internal combustion engine detected when the internal combustion engine's output transitions. This allows the stored waveform of vibration to contain a vibration component provided in the transition.
• the stored waveform of vibration can be more approximate to a waveform of vibration of the engine caused in the transition when the engine knocks.
• a detected waveform and a corrected waveform are compared and from a result thereof the determiner determines whether the engine knocks. Whether the engine knocks can thus be determined with precision.
• the present invention in another aspect provides a knock determination device for an internal combustion engine, including: a crank angle detector detecting the internal combustion engine's crank angle; a waveform detector detecting a waveform of vibration of the internal combustion engine for a predetermined crank angle range; a storage previously storing a waveform of vibration of the internal combustion engine for the predetermined crank angle range; and a determiner determining whether the internal combustion engine knocks, as based on a result of comparing the detected waveform and the stored waveform.
• the determiner determines whether the internal combustion engine knocks, as based on a result of comparing a waveform of vibration of a frequency higher than a predetermined frequency with the stored waveform.
• a crank angle detector detects an internal combustion engine's crank angle and a waveform detector detects a waveform of vibration of the internal combustion engine for a predetermined crank angle range.
• a storage previously stores a waveform of vibration of the internal combustion engine for the predetermined crank angle range and a determiner determines whether the internal combustion engine knocks, as based on a result of comparing the detected waveform and the stored waveform.
• a knock waveform model corresponding to a 1 waveform of vibration caused when the engine knocks can previously be created for example in an experiment and stored and the model and a detected waveform can be compared to determine whether the engine knocks.
• a crank angle for which vibration occurs can also be depended on to determine whether the engine knocks.
• a spark retard as compared with a predetermined crank angle (formed for example when the engine starts)
• a decision is made as to whether the internal combustion engine knocks, as based on a result of comparing a waveform of vibration of a frequency higher than a predetermined frequency with the stored waveform. If the internal combustion engine has a spark retard as compared with the predetermined crank angle, and the engine does not knock, a waveform of vibration of low frequency can nonetheless be analogous to a waveform provided when the engine knocks.
• a waveform of vibration of a frequency higher than the predetermined frequency can be compared with the stored waveform and from a result thereof whether the internal combustion engine knocks can be determined.
• This can minimize an erroneous decision that the engine knocks and thus allow whether the engine knocks to be determined with high precision.
• the knock determination device can determine with high precision whether the engine knocks.
• the present invention in still another aspect provides an ignition control system including: the knock determination device; and a spark retard device providing the internal combustion engine with a spark retard when the knock determination device determines that the internal combustion engine knocks.
• the spark retard device provides the internal combustion engine with a spark retard.
• the present invention in still another aspect provides a knock determination device for an internal combustion engine, including: a crank angle detector detecting the internal combustion engine's crank angle; a vibration detector detecting a value associated in magnitude with vibration of the internal combustion engine; a waveform detector detecting, as based on the value associated in magnitude with vibration of the internal combustion engine, a waveform of vibration of the internal combustion engine for a predetermined crank angle range; a storage previously storing a waveform of vibration of the internal combustion engine; and a determiner determining whether the internal combustion engine knocks, as based on a result of comparing the detected waveform with the stored waveform.
• the waveform detector detects the waveform of vibration of the internal combustion engine, as based on the value associated in magnitude with vibration of the internal combustion engine divided by a maximum one of values associated in magnitude with vibration detected.
• the crank angle detector detects the internal combustion engine's crank angle.
• the vibration detector detects a value associated in magnitude with vibration of the internal combustion engine.
• the waveform detector detects, as based on the value associated in magnitude with vibration of the internal combustion engine, a waveform of vibration of the internal combustion engine for a predetermined crank angle range.
• the storage previously stores a waveform of vibration of the internal combustion engine.
• the determiner determines whether the internal combustion engine knocks, as based on a result of comparing the detected waveform with the stored waveform.
• a knock waveform model corresponding to a waveform of vibration caused when the engine knocks can previously be created for example in an experiment and stored and the model and a detected waveform can be compared to determine whether the engine knocks.
• a value associated in magnitude with vibration is divided by the maximum one of values associated in magnitude with vibration detected to represent detected waveform's vibration in magnitude by a dimensionless number of 0 to 1.
• a detected waveform and a knock waveform model can be compared to determine whether the engine knocks.
• the knock determination device can determine with high precision whether the engine knocks.
• the vibration detector detects at a predetermined interval the value associated in magnitude with vibration of the internal combustion engine.
• a value associated in magnitude with vibration of the internal combustion engine can be detected at a predetermined interval.
• the determiner determines whether the internal combustion engine knocks, as based on a result of comparing the detected waveform with the stored waveform while a timing of the detected waveform attaining vibration maximized in magnitude and that of the stored waveform attaining vibration maximized in magnitude are matched.
• a detected waveform and a stored waveform can be compared at a crank angle considered as an angle for which the engine knocks.
• the knock determination device further includes a deviation calculator calculating a deviation of the detected waveform and the stored waveform.
• the determiner determines from the deviation whether the internal combustion engine knocks.
• a difference between detected and stored waveforms is represented numerically as a deviation.
• the detected waveform can be numerically analyzed to objectively determine whether the engine knocks.
• the determiner determines whether the internal combustion engine knocks from the deviation and in addition thereto the maximum value associated in magnitude with vibration of the internal combustion engine.
• vibration's magnitude can also be depended on to determine whether the engine l ⁇ iocks with higher precision.
• Fig. 1 is a control block diagram for control, showing an engine controlled by the present ignition control system in a first embodiment.
• Fig. 2 is a diagram representing a knock waveform model stored in a memory of an engine ECU in the present ignition control system in the first embodiment.
• Fig. 3 is a flow chart for illustrating a structure for control of a program executed by the engine ECU in the present ignition control system in the first embodiment.
• Fig. 4 represents a knock waveform model and an engine's vibration waveform.
• Fig. 5 is a flow chart for illustrating a structure for control of a program executed by the engine ECU in the present ignition control system in a second embodiment.
• Fig. 6 represents an engine's vibration waveform detected when spraying a fuel is stopped.
• Fig. 7 represents an uncorrected knock waveform model stored in the memory of the engine ECU in the present ignition control system in the second embodiment.
• Fig. 8 represents a knock waveform model corrected in the present ignition control system in the second embodiment.
• Fig. 9 is a flow chart for illustrating a structure for control of a program executed by the engine ECU in the present ignition control system in a third embodiment.
• Fig. 10 represents an uncorrected knock waveform model stored in the memory of the engine ECU in the present ignition control system in the third embodiment.
• Fig. 11 represents an engine's vibration waveform detected when the engine's output is in transition.
• Fig. 12 represents a knock waveform model corrected in the present ignition control system in the third embodiment.
• FIG. 13 is a flow chart for illustrating a structure for control of a program executed by the engine ECU in the present ignition control system in a fourth embodiment.
• Fig. 14 is a diagram representing a knock waveform model stored in the memory of the engine ECU in the present ignition control system in a fifth embodiment.
• Fig. 15 is a flow chart for illustrating a structure for control of a program executed by the engine ECU in the present ignition control system in the fifth embodiment.
• Fig. 16 shows an integrated value calculated for every five degrees.
• Fig. 17 represents a normalized vibration waveform.
• Fig. 18 represents a knock waveform model and an engine's vibration waveform.
• Engine 100 is an internal combustion engine that allows a mixture of air aspirated through an air cleaner 102 and a fuel injected by an injector 104 to be ignited in a combustion chamber by an ignition plug 104 and thus combusted.
• the air fuel mixture combusted causes combustion pressure which presses a piston 108 down and a crank shaft 110 rotates.
• the combusted air fuel mixture (or exhaust gas) is purified by a ternary catalyst 112 and thereafter discharged outside the vehicle.
• Engine 110 aspirates an amount of air adjusted by a throttle valve 114.
• Engine 100 is controlled by an engine ECU 200 having connected thereto a knock sensor 300, a water temperature sensor 302, a crank position sensor 306 arranged opposite a timing rotor 304, a throttle opening sensor 308, a vehicle speed sensor 310, and an ignition switch 312.
• Knock sensor 300 is implemented by a piezoelectric element. As engine 100 vibrates, knock sensor 300 generates a voltage having a magnitude corresponding to that of the vibration. Knock sensor 300 transmits a signal representing the voltage to engine ECU 200.
• Water temperature sensor 302 detects temperature of refrigerant water in engine 100 at a water jacket and transmits a signal representing a resultant detection to engine ECU 200.
• Timing rotor 304 is provided at a crank shaft 110 and rotates as crank shaft 110 do.
• Timing rotor 304 is circumferentially provided with a plurality of protrusions spaced as predetermined.
• Crank position sensor 306 is arranged opposite the protrusions of timing rotor 304. When timing rotor 304 rotates, an air gap between the protrusions of timing rotor 304 and crank position sensor 306 varies, and a coil portion of crank position sensor 306 passes an increased/decreased magnetic flux and thus experiences electromotive force.
• Crank position sensor 306 transmits a signal representing the electromotive force to engine ECU 200. From the signal, engine ECU
• Throttle opening sensor 308 detects a throttle opening and transmits a signal representing a resultant detection to engine ECU 200.
• Vehicle speed sensor 310 detects a rate of rotation of a wheel (not shown) and transmits a signal representing a resultant detection to engine ECU 200. From the wheel's rate of rotation engine ECU 200 calculates the vehicle's speed.
• Ignition switch 312 is turned on by a driver starting engine 100.
• Engine ECU 200 uses the signals transmitted from each sensor and ignition switch 312 and a map and program stored in a memory 202 to perform an arithmetic operation to control equipment so that engine 100 has a desired driving condition.
• engine ECU 200 depends on a signal transmitted from knock sensor 300 and a crank angle to detect a waveform of vibration of engine 100 at a predetermined knock detection gate (a section from a predetermined first crank angle to a predetermined second crank angle) (hereinafter the waveform will also simply be referred to as "vibration waveform") and from the detected vibration waveform determines whether engine 100 knocks.
• a predetermined knock detection gate a section from a predetermined first crank angle to a predetermined second crank angle
• vibration waveform determines whether engine 100 knocks.
• the engine ECU 200 memory 202 stores a knock waveform model corresponding to a model of a waveform of vibration caused when engine 100 knocks, as shown in Fig. 2.
• the model is stored in association with vibration of a plurality of frequency bands. More specifically, a plurality of such models are stored.
• the models are obtained as follows: an experiment or the like is conducted to cause engine 100 to knock to detect the engine's vibration waveform, from which the models are previously created and stored. It should be noted, however, that the models may be created by a different method.
• Engine ECU 200 compares a detected waveform with the stored models to determine whether engine 100 knocks. With reference to Fig. 3, in present embodiment's ignition control system engine ECU 200 executes a program controlled in a structure as will be described hereinafter.
• S engine ECU 200 detects the engine 100 vibration waveform based on a signal transmitted from knock sensor 300 and a crank angle.
• engine ECU 200 determines for all frequency bands whether any detected vibration waveform matches any stored knock waveform model within a predetermined range. In the present embodiment whether the detected vibration waveform and the model match within the predetermined range may be determined for example by whether for each crank angle the engine 100 vibrates with a deviation falling within a reference value or whether such deviations averaged fall within the reference value. Note that a method different than the above may alternatively be employed to determine whether the detected waveform and the stored model match within the predetermined range. If the detected waveform and the stored model match within the predetermined range (YES at SI 02) the control proceeds with SI 04. Otherwise (NO at SI 02) the control proceeds with SI 08. At SI 04 engine ECU 200 determines that engine 100 knocks.
• engine ECU 200 introduces a spark retard.
• engine ECU 200 determines that engine 100 does not knock.
• engine ECU 200 introduces a spark advance.
• ignition control system engine ECU 200 operates as will be described hereinafter.
• the engine ECU depends on a signal received from a knock sensor and a crank angle to detect the engine's vibration waveform at a predetermined knock detection gate and compares the vibration waveform with a knock waveform model to determine whether the engine knocks.
• a crank angle for which vibration occurs can also be depended on to determine whether the engine knocks. Consequently, whether engine l ⁇ iocks or not can be determined with high precision.
• the present embodiment's ignition control system has engine ECU 200 executing a program controlled in a structure as will be described hereinafter. Note that engine ECU 200 executes the program described in the first embodiment and in addition thereto a program as will be described hereinafter.
• engine ECU 200 determines whether injector 100 is interrupted from injecting a fuel (hereinafter also referred to as "the fuel is cut"). Whether the fuel is cut may be determined by whether the vehicle is in a driving condition cutting the fuel (e.g., whether the accelerator is turned off and the engine rotates at at least a predetermined rate). If the fuel is cut (YES at S200) the control proceeds with S202, otherwise (NO at S202) this process ends.
• engine ECU 200 detects the engine 100 vibration waveform from a signal transmitted from knock sensor 300 and a crank angle.
• engine ECU 200 depends on the detected vibration waveform to correct a knock waveform model stored in memory 202.
• ignition control system engine ECU 200 operates as will be described hereinafter.
• vibration detected by knock sensor 300 constantly contains mechanical vibration of engine 100 itself.
• the engine 100 itself s mechanical vibration affects so that a detected vibration waveform may not match the model.
• the model has the waveform of the mechanical vibration of engine 100 itself added thereto to correct the model, as shown in Fig. 8 (S204).
• the model can be more approximate to a waveform of vibration of engine 100 caused when the engine knocks.
• the engine ECU corrects a knock waveform model in a memory by mechanical vibration of the engine itself detected when the fuel is cut.
• the present invention in a third embodiment will be described.
• the present embodiment is distinguished from the first embodiment by correcting a knock waveform model.
• the remainder in configuration and function is identical to the first embodiment.
• the present embodiment's ignition control system has engine ECU 200 executing a program controlled in a structure as will be described hereinafter.
• engine ECU 200 executes the program described in the first embodiment and in addition thereto a program as will be described hereinafter.
• engine ECU 200 determines whether the engine 100 provides an output that transitions (or varies).
• Whether the engine 100 output is in transition may be determined for example by whether a throttle opening's variation rate, aspirated air's temperature, the engine 100 refrigerant water's temperature and the like are larger in value than predetermined. If the engine 100 output is in transition (YES at S300), the control proceeds with S302. Otherwise (NO at S300) this process ends.
• engine ECU 200 detects the engine 100 vibration waveform from a signal received from knock sensor 300.
• engine ECU 200 determines whether the detected vibration waveform does not contain a vibration component attributed to knocking. This decision may be made for example by whether the vibration waveform has a peak having a value smaller than a predetermined value. If the detected vibration waveform does not contain a vibration component attributed to knocking (YES at S304), the control proceeds with S306. Otherwise (NO at S304) this process ends.
• engine ECU 200 corrects a knock waveform model in memory 202, as based on the detected vibration waveform.
• engine ECU 200 operates as will be described hereinafter. If the engine 100 output is in transition (YES at S300) the engine 100 vibration waveform is detected (S302). If the engine 100 output is in transition, the engine tends to knock, and it is necessary to determine with high precision whether the engine has knocked. When the engine's output is in transition, however, the engine 100 vibration varies even if the engine does not knock. As such, if the Fig.
• the engine ECU corrects a knock waveform model stored in a memory by a vibration waveform detected when the engine's output is in transition.
• the model can be more approximate to a vibration waveform caused when the engine knocks, and whether- the engine knocks or not can be determined with high precision.
• Fourth Embodiment With reference to Fig. 13 the present embodiment in a fourth embodiment will be described. While in the first embodiment a decision as to whether an engine knocks is made from waveforms of vibrations of all frequency bands, in the present embodiment such decision is made from a waveform of vibration of a frequency equal to or larger than a predetermined frequency. The remainder in configuration and hence function is identical to the first embodiment. With reference to Fig.
• engine ECU 200 executes a program controlled in a structure as will be described hereinafter.
• engine ECU 200 determines whether engine 100 is controlled to have a spark retard from a predetermined crank angle (formed for example when engine 100 starts) (hereinafter such control will also be referred to as "spark retard control"). Whether spark retard control is effected may be determined from whether the vehicle is in a condition subject to spark retard, such as whether the catalyst's temperature is lower than a predetermined temperature, whether the vehicle is rapidly accelerated, or the like. If spark retard control is effected (YES at S400), the control proceeds with S402, otherwise (NO at S400) this process ends.
• engine ECU 200 detects the engine 100 vibration waveform based on a signal transmitted from knock sensor 300.
• engine ECU 200 determines whether a detected vibration waveform that is equal to or higher than a predetermined frequency matches a knock waveform model stored in memory 202 within a predetermined range. More specifically, whether the engine knocks is not determined for waveforms of vibration of low frequency. If the model and the detected vibration waveform match within the predetermined range (YES at S404) the control proceeds with S406, otherwise (NO at S404) the control proceeds with S410.
• S406 engine ECU 200 determines that engine 100 knocks.
• ECU 200 introduces a spark retard.
• engine ECU 200 determines that engine 100 does not knock.
• engine ECU 200 introduces a spark advance.
• spark retard control is effected (YES at S400)
• the engine 100 vibration waveform is detected (S402).
• spark retard control there exists a crank angle range for which a waveform of vibration of low frequency is analogous to a waveform provided when the engine knocks despite that the engine does not knock (hereinafter this range will be referred to as a pseudo knock range).
• a decision that the engine knocks may erroneously be made despite that the engine does not knock.
• a decision is made as to whether a detected vibration waveform that is equal to or higher than a predetermined frequency matches a knock waveform model stored in memory
• Fifth Embodiment With reference to Figs. 14-18 the present invention in a fifth embodiment will be described.
• the present invention differs from the first embodiment in that waveforms of vibration of different frequency bands are composited together to detect a vibration waveform.
• a nock waveform model provides vibration having a magnitude that does not uniquely correspond to a crank angle.
• the remainder in configuration and hence function is, identical to the first embodiment. As shown in Fig.
• the engine ECU 200 memory 202 has stored therein a knock waveform model corresponding to a portion of vibration, represented in magnitude, caused by knocking that follows a peak.
• a knock waveform model that corresponds to vibration attributed to knocking following the rise of the . vibration, may be stored.
• vibration's magnitude is represented by a dimensionless number of
• the model is a wave of a composition of vibration of frequency bands.
• Fig. 14, CA represents a crank angle.
• ignition control system engine ECU 200 executes a program controlled in a structure as will be described hereinafter.
• engine ECU 200 detects the engine 100 vibration in magnitude from a signal transmitted from knock sensor 300.
• the vibration's magnitude is represented by a value of voltage output from knock sensor -300.
• the vibration's magnitude may be represented by a value corresponding to the value of the voltage output from knock sensor 300.
• the vibration's magnitude is detected in a combustion process for an angle from a top dead center to (a crank angle of) 90°.
• engine ECU 200 calculates for a crank angle of every five degrees an integration (hereinafter also be referred to as an "integrated value") of values of voltage output from knock sensor 300 (i.e., representing magnitude of vibration).
• the integrated value is calculated for vibration of each frequency band.
• a waveform of vibration of each frequency band is detected.
• the integrated value may be calculated for a crank angle other than every five degrees.
• engine ECU 200 composites waveforms of vibration of frequency bands. Thus engine 100 vibration waveform is detected.
• engine ECU 200 uses the largest integrated value of waveforms of vibration composited to normalize the engine's vibration waveform.
• normalizing a waveform means dividing each integrated value by the largest integrated value to represent the vibration's magnitude by a dimensionless number of 0 to 1.
• engine ECU 200 calculates a coefficient of correlation K, a value associated with a deviation of a normalized vibration waveform and a knock waveform model.
• a timing of the normalized vibration waveform achieving vibration maximized in magnitude and that of the model achieving vibration maximized in magnitude are matched, while the deviation in absolute value (or an amount of offset) of the normalized vibration waveform and the model is calculated for each crank angle (of five degrees) to calculate the coefficient of correlation K.
• knock intensity N P x K / BGL.
• the BGL is stored in memory 202. Note that knock intensity N may be calculated by a different method.
• engine ECU 200 determines whether knock intensity N is larger than a predetermined reference value. If so (YES at S512) the control proceeds with S514, otherwise (NO at S512) the control proceeds with S518.
• engine ECU 200 determines that engine 100 knocks.
• engine ECU 200 introduces a spark retard.
• engine ECU 200 determines that engine 100 does not knock.
• engine ECU 200 introduces a spark advance.
• engine ECU 200 operates as will be described hereinafter.
• the engine 100 vibration is detected in magnitude from a signal transmitted from knock sensor 300 (S500).
• S500 knock sensor 300
• S502 integrated value for every five degrees is calculated for each frequency
• S504 integrated values calculated for the frequencies are composited together.
• the engine 100 vibration waveform is detected. Note that while Fig. 16 represents a vibration waveform in a rectangle, each integrated value may be connected by a line to represent the vibration waveform.
• each integrated value alone may be represented in a dot to represent the vibration waveform.
• Using an integrated value for every five degrees to detect a vibration waveform allows minimized detection of a waveform of vibration having a complicated form attributed to vibration having a magnitude varying minutely. This can help to compare a detected vibration waveform with a knock waveform model.
• the maximum integrated value is used to normalize the engine's vibration waveform (S506).
• the integrated value for 15° to 20° is used to normalize the engine's vibration waveform for the sake of illustration.
• an integrated value for each crank angle is divided by that for 15 to 20° and, as shown in Fig.
• the magnitude of vibration in the vibration waveform is represented by a dimensionless number of 0 to 1.
• a detected vibration waveform and a knock waveform model can be compared regardless of magnitude of vibration. This can eliminate the necessity of storing a large number of knock waveform models corresponding to magnitude of vibration and thus help to create a knock waveform model.
• a timing of a normalized vibration waveform providing vibration maximized in magnitude and that of a knock waveform model providing vibration maximized in magnitude are matched, while a deviation in absolute value ⁇ S (I) of the normalized vibration waveform and the knock waveform model is calculated for each crank angle.
• knock intensity N is larger than a predetermined reference value (YES at S512) a decision is made that engine knocks (S514) and a spark retard is introduced (S516) to prevent the engine from knocking. If knock intensity N is not larger than the predetermined reference value (NO at S512), a decision is made that the engine does not knock (S108) and a spark advance is introduced (SI 10).
• the engine ECU detects the engine's vibration waveform based on a signal transmitted from a knock sensor and compares the vibration waveform with a knock vibration model to calculate the coefficient of correlation K. Furthermore, the product of the coefficient of correlation K and the vibration waveform's maximum integrated value P is divided by the BGL to calculate knock intensity N.
• knock intensity N is larger than a reference value
• vibration's magnitude can also be depended on to analyze in more detail whether the engine's vibration is attributed to knocking. Thus whether the engine knocks or not can be determined with high precision.

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• Combined Controls Of Internal Combustion Engines (AREA)
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