1. A combustion air-fuel ratio control system for an internal combustion engine comprising:
exhaust guiding means for guiding exhaust from the internal combustion engine;
exhaust purification means, arranged downstream of the exhaust guiding means, for purifying the exhaust;
fresh air supplying means for supplying fresh air to the exhaust guiding means at a fresh air supplying position upstream of the exhaust purification means;
exhaust air-fuel ratio sensing means for detecting an exhaust air-fuel ratio of the exhaust at a location between the exhaust purification means and the fresh air supplying position;
exhaust air-fuel ratio sensor activation determining means for determining whether or not the exhaust air-fuel ratio sensing means is active; and
combustion air-fuel ratio control means for controlling a combustion air-fuel ratio of the internal combustion engine based on the exhaust air-fuel ratio that is detected by the exhaust air-fuel ratio sensing means by controlling the fresh air from the fresh air supplying means to the exhaust guiding means when warming up of the exhaust purification means is requested,
the combustion air-fuel ratio control means further performing a function of open controlling the combustion air-fuel ratio in a combustion chamber to be a primary combustion air-fuel ratio which is between a theoretical air-fuel ratio and a combustion limit air-fuel ratio that is richer than the theoretical air-fuel ratio upon the exhaust air-fuel ratio sensor activation determining means determining the exhaust air-fuel ratio sensing means to be inactive, and
the combustion air-fuel ratio control means further performing a function of feedback controlling the combustion air-fuel ratio to be a secondary combustion air-fuel ratio that is richer than the primary combustion air-fuel ratio and upon the exhaust air-fuel ratio sensor activation determining means determining the exhaust air-fuel ratio sensing means to be active.
2. A combustion air-fuel ratio control system for an internal combustion engine comprising:
an exhaust passage where exhaust from the internal combustion engine is guided;
an exhaust purification catalyst arranged downstream of the exhaust passage;
a fresh air supplying device arranged upstream of the exhaust purification catalyst to supply fresh air to the exhaust passage;
an exhaust air-fuel ratio sensor disposed between the exhaust purification catalyst and the fresh air supplying device and arranged to detect an exhaust air-fuel ratio of the exhaust;
an exhaust air-fuel ratio sensor activation determining unit that determines whether or not the exhaust air-fuel ratio sensor is active; and
a combustion air-fuel ratio control unit configured to control a combustion air-fuel ratio of the internal combustion engine based on the exhaust air-fuel ratio that is detected by the exhaust air-fuel ratio sensor by controlling the fresh air from the fresh air supplying device to the exhaust passage when warming up of the exhaust purification catalyst is requested,
the combustion air-fuel ratio control unit open controlling the combustion air-fuel ratio to a primary combustion air-fuel ratio which is between a theoretical air-fuel ratio and a combustion limit air-fuel ratio that is richer than the theoretical air-fuel ratio upon the exhaust air-fuel ratio sensor activation determining unit determining the exhaust air-fuel ratio sensor to be inactive, and
the combustion air-fuel ratio control unit feedback controlling the combustion air-fuel ratio to a secondary combustion air-fuel ratio that is richer than the primary combustion air-fuel ratio upon the exhaust air-fuel ratio sensor activation determining unit determining the exhaust air-fuel ratio sensor to be active.
3. The combustion air-fuel ratio control system for an internal combustion engine according to claim 2, further including
an air amount detection unit that detects fresh air amount supplied to the exhaust passage, and a combustion air-fuel ratio estimation unit that estimate the combustion air-fuel ratio based on current fuel supply amount and the fresh air amount detected by the fresh air amount detection unit.
4. The combustion air-fuel ratio control system for an internal combustion engine according to claim 2, further including
an operation condition determination unit that detects whether an operating condition of the internal combustion engine is stationary or non-stationary, wherein when the operation condition determination unit determines that the operating condition is non-stationary, even if the exhaust air-fuel ratio sensor is active, the combustion air-fuel ratio control unit open-controls the combustion air-fuel ratio to be the primary combustion air-fuel ratio.
5. The combustion air-fuel ratio control system for an internal combustion engine according to claim 4, further including
an intake air amount detection unit that detects an intake air amount to the internal combustion engine, wherein the operation condition determination unit determines that the operating condition is non-stationary when a change rate of the intake air amount to the internal combustion engine is at or greater than a predetermined value.
6. The combustion air-fuel ratio control system for an internal combustion engine according to claim 2, wherein
the combustion air-fuel ratio control unit includes a change rate limiting unit that limits a change rate of the combustion air-fuel ratio when open control or feedback control is carried out.
7. An air-fuel ratio controlling method for an internal combustion engine, including an exhaust purification catalyst that is arranged in an exhaust passage where exhaust from the internal combustion engine flows, a fresh air supplying device that supplies fresh air upstream of the exhaust purification catalyst, an exhaust air-fuel ratio sensor that detects an exhaust air-fuel ratio between the exhaust purification catalyst and the fresh air supplying device in the exhaust passage, the air-fuel ratio controlling method comprising:
determining whether or not the exhaust air-fuel ratio sensor is active;
determining timing of a request for warming up the exhaust purification catalyst;
setting a combustion air-fuel ratio to a primary combustion air-fuel ratio, which is between a theoretical air-fuel ratio and a combustion limit air-fuel ratio, which is richer than the theoretical air-fuel ratio and allows stable combustion in an open control, while supplying fresh air from the fresh air supplying device to the exhaust passage, when warming up of the exhaust purification catalyst is required, and the exhaust air-fuel ratio sensor is inactive; and
setting the combustion air-fuel ratio to a secondary combustion air-fuel ratio, which is richer than the primary combustion air-fuel ratio and close to the combustion limit air-fuel ratio in a feedback control, while supplying fresh air from the fresh air supplying device to the exhaust passage, when the warming up of the exhaust purification catalyst is required, and the exhaust air-fuel ratio sensor is active.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An inputoutput (IO) circuit comprising:
an electrostatic discharge (ESD) protection circuit electrically coupled with an output node of the IO circuit;
at least one inductor and at least one loading electrically coupled in a series fashion and between the output node of the IO circuit and a power line; and
a circuitry electrically coupled with a node between the at least one inductor and the at least one loading, wherein the circuitry is operable to increase a current flowing through the at least one inductor during a signal transition.
2. The IO circuit of claim 1, wherein the circuitry comprises at least one pre-driver stage having at least one output node, and the at least one output node of the at least one pre-driver stage is electrically coupled with at least one input node of a driver stage.
3. The IO circuit of claim 2, wherein the at least one pre-driver stage comprises:
a first pre-driver stage that is electrically coupled with the node between the at least one loading and the at least one inductor, and electrically coupled with the driver stage; and
a second pre-driver stage that is electrically coupled with the node between the at least one loading and the at least one inductor, and electrically coupled with the first pre-driver stage.
4. The IO circuit of claim 3, wherein during the signal transition a first current flows through the driver stage, a second current flows through the first pre-driver stage, a third current flows through the second pre-driver stage, and the first, second and third currents are substantially equal to each other.
5. The IO circuit of claim 1, wherein the circuitry comprises at least one level shifter having at least one output node, and the at least one output node of the at least one level shifter is electrically coupled with at least one input node of a driver stage.
6. The IO circuit of claim 5, wherein the at least one level shifter comprises:
a first level shifter that is electrically coupled with the node between the at least one inductor and the at least one loading, and electrically coupled with the driver stage; and
a second level shifter that is electrically coupled with the node between the at least one inductor and the at least one loading, and electrically coupled with the first level shifter.
7. The IO circuit of claim 6, wherein during the signal transition a first current flows through the driver stage, a second current flows through the first level shifter, a third current flows through the second level shifter, and the first, second and third currents are substantially equal to each other.
8. The IO circuit of claim 6, wherein during a steady state a current flowing through the first and second level shifters is substantially zero.
9. The IO circuit of claim 8, wherein the ESD protection circuit has a parasitic capacitance of about 400 femtofarads (fF) or more, and the at least one inductor has an inductance of about 0.1 nanohenry (nH) or less.
10. An inputoutput (IO) circuit comprising:
a driver stage comprising:
a first electrostatic discharge (ESD) protection circuit electrically coupled with a first output node of the driver stage;
a second ESD protection circuit electrically coupled with a second output node of the driver stage;
a first inductor and a first resistor electrically coupled in a series fashion and between the first output node of the driver stage and a power line; and
a second inductor and a second resistor electrically coupled in a series fashion and between the second output node of the driver stage and the power line; and
a first circuit electrically coupled with a first node between the first inductor and the first resistor and a second node between the second inductor and the second resistor, a first output node of the first circuit and a second output node of the first circuit are electrically coupled with a first input node and a second input node of the driver stage, respectively; and
a second circuit electrically coupled with the first node between the first inductor and the first resistor and the second node between the second inductor and the second resistor, a first output node of the second circuit and a second output node of the second circuit are electrically coupled with a first input node of the first circuit and a second input node of the first circuit, respectively.
11. The IO circuit of claim 10, wherein the first circuit and the second circuit comprise a pre-driver stage or a level shifter.
12. The IO circuit of claim 10, wherein the first circuit and the second circuit each are operable to increase a current flowing through the first inductor or the second inductor during a signal transition.
13. The IO circuit of claim 10, wherein during the signal transition a first current flows through the driver stage, a second current flows through the first circuit, a third current flows through the second circuit, and the first, second and third currents are substantially equal to each other.
14. The IO circuit of claim 10, wherein during a steady state a current flowing through the first and second circuits is substantially zero.
15. The IO circuit of claim 10, wherein the first and second ESD protection circuits each have a parasitic capacitance of about 400 femtofarads (fF) or more, and the first and second inductors each have an inductance of about 0.1 nanohenry (nH) or less.
16. An inputoutput (IO) circuit comprising:
a driver stage comprising:
a first electrostatic discharge (ESD) protection circuit electrically coupled with a first output node of the driver stage;
a second ESD protection circuit electrically coupled with a second output node of the driver stage;
a first inductor and a first resistor electrically coupled in a series fashion and between the first output node of the driver stage and a power line; and
a second inductor and a second resistor electrically coupled in a series fashion and between the second output node of the driver stage and the power line; and
a first level shifter electrically coupled with a first node between the first inductor and the first resistor and a second node between the second inductor and the second resistor, a first output node of the first level shifter and a second output node of the first level shifter are electrically coupled with a first input node and a second input node of the driver stage, respectively, wherein during a signal transition the first level shifter is operable to increase a current flowing through the first or second inductor; and
a second level shifter electrically coupled with the first node between the first inductor and the first resistor and the second node between the second inductor and the second resistor, a first output node of the second level shifter and a second output node of the second level shifter are electrically coupled with a first input node of the first level shifter and a second input node of the first level shifter, respectively, wherein during the signal transition the second level shifter is operable to increase a current flowing through the first or second inductor.
17. The IO circuit of claim 16, wherein during the signal transition a first current flows through the driver stage, a second current flows through the first level shifter, a third current flows through the second level shifter, and the first, second and third currents are substantially equal to each other.
18. The IO circuit of claim 16, wherein the first and second ESD protection circuits each have a parasitic capacitance of about 400 femtofarads (fF) or more, and the first and second inductors each have an inductance of about 0.1 nanohenry (nH) or less.
19. The IO circuit of claim 16, wherein during a steady state a current flowing through the first and second level shifters is substantially zero.