Abstract: This fuel property estimation device is used in an internal combustion engine that uses a mixed fuel of three kinds of fuel and includes a first sensor that outputs a signal responsive to a physical property of the fuel in a fuel route and a second sensor outputs a signal responsive to an oxygen concentration of exhaust gas. This device measures a physical property value of the mixed fuel based on a first sensor signal, and calculates an air-fuel ratio value at stoichiometric combustion state using feedback of a second sensor signal. This device estimates a composition ratio of the mixed fuel based on the measured physical property value and the calculated air-fuel ratio value by referring to a relationship between the composition ratio of the mixed fuel and the physical property value and a relationship between the composition ratio of the mixed fuel and a theoretical air-fuel ratio value.

Abstract: This fuel property estimation device is used in an internal combustion engine that uses a mixed fuel of three kinds of fuel and includes a first sensor that outputs a signal responsive to a physical property of the fuel in a fuel route and a second sensor outputs a signal responsive to an oxygen concentration of exhaust gas. This device measures a physical property value of the mixed fuel based on a first sensor signal, and calculates an air-fuel ratio value at stoichiometric combustion state using feedback of a second sensor signal. This device estimates a composition ratio of the mixed fuel based on the measured physical property value and the calculated air-fuel ratio value by referring to a relationship between the composition ratio of the mixed fuel and the physical property value and a relationship between the composition ratio of the mixed fuel and a theoretical air-fuel ratio value.

Abstract: With an increase in torque demand, the internal combustion engine of the invention successively changes over a combination of a compression ratio, an air-fuel ratio, and a boost status of an air-fuel mixture from (1) settings of a high compression ratio, a lean air-fuel ratio, and a non-boosting state, (2) settings of the high compression ratio, the lean air-fuel ratio, and a boosting state, (3) settings of a low compression ratio, the lean air-fuel ratio, and the boosting state, to (4) settings of the low compression ratio, a stoichiometric air-fuel ratio, and the boosting state. The changeover strategy desirably widens a driving area of the internal combustion engine at the high compression ratio of a high thermal efficiency or at the lean air-fuel ratio. Under the condition of a large torque demand, the internal combustion engine is driven with boosting the stoichiometric air-fuel mixture at the low compression ratio to output a sufficiently large torque.

Abstract: With an increase in torque demand, the internal combustion engine of the invention successively changes over a combination of a compression ratio, an air-fuel ratio, and a boost status of an air-fuel mixture from (1) settings of a high compression ratio, a lean air-fuel ratio, and a non-boosting state, (2) settings of the high compression ratio, the lean air-fuel ratio, and a boosting state, (3) settings of a low compression ratio, the lean air-fuel ratio, and the boosting state, to (4) settings of the low compression ratio, a stoichiometric air-fuel ratio, and the boosting state. The changeover strategy desirably widens a driving area of the internal combustion engine at the high compression ratio of a high thermal efficiency or at the lean air-fuel ratio. Under the condition of a large torque demand, the internal combustion engine is driven with boosting the stoichiometric air-fuel mixture at the low compression ratio to output a sufficiently large torque.

Abstract: An internal combustion engine is capable of changing a compression ratio according to an output torque. A motor is connected with an output shaft of the internal combustion engine to transmit torque to and from the output shaft. The internal combustion engine detects a torque demand required to the internal combustion engine. When the torque demand exceeds a threshold torque, which is set in advance for changeover of setting of the compression ratio in the internal combustion engine, the motor is controlled to output a torque to the output shaft. The torque output from the motor restricts the output torque of the internal combustion engine to be not greater than the threshold torque. Such control effectively prevents frequent changeover of the setting of the compression ratio in the internal combustion engine. This arrangement desirably saves energy required for the frequent changeover of the compression ratio and thus enhances the total efficiency of the internal combustion engine.

Abstract: An internal combustion engine is capable of changing a compression ratio according to an output torque. A motor is connected with an output shaft of the internal combustion engine to transmit torque to and from the output shaft. The internal combustion engine detects a torque demand required to the internal combustion engine. When the torque demand exceeds a threshold torque, which is set in advance for changeover of setting of the compression ratio in the internal combustion engine, the motor is controlled to output a torque to the output shaft. The torque output from the motor restricts the output torque of the internal combustion engine to be not greater than the threshold torque. Such control effectively prevents frequent changeover of the setting of the compression ratio in the internal combustion engine. This arrangement desirably saves energy required for the frequent changeover of the compression ratio and thus enhances the total efficiency of the internal combustion engine.

Abstract: With an increase in torque demand, the internal combustion engine of the invention successively changes over a combination of a compression ratio, an air-fuel ratio, and a boost status of an air-fuel mixture from (1) settings of a high compression ratio, a lean air-fuel ratio, and a non-boosting state, (2) settings of the high compression ratio, the lean air-fuel ratio, and a boosting state, (3) settings of a low compression ratio, the lean air-fuel ratio, and the boosting state, to (4) settings of the low compression ratio, a stoichiometric air-fuel ratio, and the boosting state. The changeover strategy desirably widens a driving area of the internal combustion engine at the high compression ratio of a high thermal efficiency or at the lean air-fuel ratio. Under the condition of a large torque demand, the internal combustion engine is driven with boosting the stoichiometric air-fuel mixture at the low compression ratio to output a sufficiently large torque.

Abstract: An internal combustion engine is provided with a VVT mechanism capable of adjusting overlap period in which both intake and exhaust valves are open. The internal combustion engine is also provided with a recirculation mechanism that recirculates exhaust gas to the intake side. An EGR map from which internal EGR amount based on the VVT mechanism and external EGR amount based on the recirculation mechanism are derived in accordance with engine speed and engine torque is prepared. The EGR map is realized as a four-dimensional map that also takes engine intake air temperature and engine coolant temperature into account. By performing EGR control in consideration of these parameters, the occurrence of knocking during EGR control can be suppressed, and an improvement in fuel consumption and the like can be achieved with certainty.

Abstract: A control system for a vehicle in which an internal combustion engine whose output torque is controlled based on a required output power is coupled to a continuously variable transmission whose input rotation speed is controlled based on the required output power. A controller of the system determines a final target operating point of the engine which is defined by the output torque and the input rotation speed, on the basis of the required output power, and sets a transient operating point to one of possible operating points that can be achieved within a predetermined period of time such that the operating point of the engine approaches the final target operating point. The controller then controls the output torque and the input rotation speed of the continuously variable transmission so as to operate the engine at the set transient operating point.

Abstract: An internal combustion engine is provided with a VVT mechanism capable of adjusting overlap period in which both intake and exhaust valves are open. The internal combustion engine is also provided with a recirculation mechanism that recirculates exhaust gas to the intake side. An EGR map from which internal EGR amount based on the VVT mechanism and external EGR amount based on the recirculation mechanism are derived in accordance with engine speed and engine torque is prepared. The EGR map is realized as a four-dimensional map that also takes engine intake air temperature and engine coolant temperature into account. By performing EGR control in consideration of these parameters, the occurrence of knocking during EGR control can be suppressed, and an improvement in fuel consumption and the like can be achieved with certainty.

Abstract: A control system for a vehicle in which an internal combustion engine whose output torque is controlled based on a required output power is coupled to a continuously variable transmission whose input rotation speed is controlled based on the required output power. A controller of the system determines a final target operating point of the engine which is defined by the output torque and the input rotation speed, on the basis of the required output power, and sets a transient operating point to one of possible operating points that can be achieved within a predetermined period of time such that the operating point of the engine approaches the final target operating point. The controller then controls the output torque and the input rotation speed of the continuously variable transmission so as to operate the engine at the set transient operating point.

Abstract: In a direct fuel injection engine, an ignition coil generates a high voltage applied to a spark plug at a desired ignition time and a similar ignition voltage is then continued to be repeatedly generated at a fixed frequency so that the spark plug generates multiple sparks in each ignition cycle. The number of sparks included in the multiple is reduced as an engine speed rises. The multiple spark generating operation is disabled when the engine is in a high speed and/or high load region of operation.

Abstract: An ion current detection device is disclosed that is designed to hold an ion current output voltage within a prescribed limit to ensure proper operation of a processing device connected to the output side thereof, while, at the same time, shortening the decay time of the LC resonance associated with an ignition coil. An ion current flows from one end of a capacitor and back to the other end thereof passing through an ignition coil secondary winding, a spark plug, an ion current detecting resistor, and a load resistor. A voltage equal to -(ion current value).times.detecting resistor value appears at a node between the ion current detecting resistor and the load resistor. This voltage is inverted by an inverting circuit and supplied as an ion current output to the processing circuit.

Abstract: A knock detection device for an internal combustion engine make provisions to prevent erroneous decisions from being made due to a steplike signal change at the time of mask removal or to an overlap between an LC resonance generation period and a knock occurrence period in high engine rpm conditions. A low-frequency component is removed from an ion current signal by an HPF, and the resulting flat signal is supplied to a mask circuit, thereby reducing the amount of discontinuity occurring at the time of mask removal and suppressing noise in an output signal of a BPF to a level that does not affect knock detection. Further, by setting the gate period in a peak-hold circuit slightly delayed with respect to the mask removal timing, noise associated with the mask removal is completely eliminated.

Abstract: A combustion state detector apparatus for an internal combustion engine has a current detection device for detecting a current flowing between the ignition plug and a ground, and an ignition driving device for driving the ignition plug on the basis of an ignition instruction signal from an electronic control device of the internal combustion engine. An independent unit including a current detection device and an ignition driving device, is provided for each cylinder of the internal combustion engine. With respect to each cylinder, the apparatus determines whether a misfire has occurred on the basis of the current flowing between the ignition plug and the ground at the time of combustion. The apparatus is also capable of detecting abnormalities and/or wire breakages in a signal system provided for signal transmission between each independent unit and the electronic control device of the internal combustion engine.

Abstract: A knock detection device for an internal combustion engine prevents erroneous knock detection decisions from being made due to an LC resonant current in an ion current path. An LC resonance frequency, which is determined based on an inductance of ignition coil secondary and a stray capacitance formed in the ion current path, is set so as to be displaced from a knock frequency so that the knock frequency component alone can be detected accurately from the ion current output. Preferably, the inductance of the ignition coil secondary is set to a large value, thereby setting the LC resonance frequency lower than the knock frequency and thus improving ignitability as well as knock detectability. Also preferably, the LC resonance frequency is set to a value lower than a lower cut-off frequency of a knock signal extraction band-pass filter provided in a processing circuit. This ensures more reliable elimination of the noise causing LC resonance frequency component.

Abstract: The invention provides a preignition detection device that is capable of detecting a preignition condition (PI) in an incipient stage. Engine vibration is detected by a vibration sensor 113 and read into a controller 12. When the length of a period during which abnormal vibration of a magnitude greater than a predetermined level occurs in succession has exceeded a predetermined length of period, or when the frequency of occurrence of abnormal vibration during a predetermined period is greater than a predetermined value and the cumulative sum of the frequencies of occurrence of abnormal vibration has exceeded a predetermined value, then it is determined that preignition has occurred. Here, a determination value, based on which the occurrence of preignition is determined, can be varied to prevent erroneous decisions and to improve responsiveness.

Abstract: A device for detecting knocking in an internal combustion engine which, when spike noise or noise due to disturbance in the flame in low-load running are generated, does not erroneously detect it as knocking. Knocking frequency components passing through a band-pass filter 32 and frequency components lower than the knocking frequency and passing through a low-load noise band-pass filter 321 are picked from the ionic current detected by an ionic current detecting unit 17. When the level of the low-frequency components is larger than a predetermined value, it is regarded that the noise is generated due to unstable combustion during the low-load operation or the spike noise is generated due to corona discharge of a spark plug 16, and the determination of the occurrence of knocking is prevented. This constitution makes it possible to prevent erroneous detection of knocking.

Abstract: An apparatus for detecting a condition of burning in an internal combustion engine includes a spark plug and an ignition coil. The ignition coil has a primary winding and a secondary winding. The secondary winding is connected to the spark plug. An ion current sensing resistor is connected to a low voltage side of the secondary winding of the ignition coil for sensing an ion current. A diode is connected in parallel with the primary winding of the ignition coil. A switching element is connected in series with the primary winding of the ignition coil. The switching element is movable into and out of an on state. A suitable device is operative for resisting a current flowing through the diode when the switching element is in the on state.

Abstract: A device for controlling knocking includes a first unit which applies a voltage across a pair of electrodes installed in a combustion chamber of the internal combustion engine, detects an ionic current flowing between said pair of electrodes through ions generated when a gas mixture in the combustion chamber burns, and discriminates whether the knocking is occurring or not based upon the ionic current that is detected. The device for controlling knocking further includes a second unit which detects vibration of the cylinder block by using a vibration sensor installed in the cylinder block of the internal combustion engine, and discriminates whether the knocking is occurring or not based upon the vibration of the cylinder block that is detected. The device for controlling knocking controls the ignition timing of the internal combustion engine based upon the result of discrimination of either the first unit or the second unit depending upon the operation region of the internal combustion engine.