TWI458971B - Activation determining system for oxygen sensor and saddle-ride type vehicle - Google Patents

Description

Oxygen sensor activity determination system and straddle type vehicle

The present invention relates to an activity determination system for an oxygen sensor.

Oxygen sensors have heretofore been used to appropriately control the air-fuel ratio of the mixed gas to be supplied to the internal combustion engine. The output value from the oxygen sensor varies depending on the concentration of oxygen in the exhaust gas. Therefore, it is possible to obtain the concentration of oxygen in the exhaust gas by detecting the output value from the oxygen sensor. Further, based on the output value from the oxygen sensor, which of the surplus state and the lean state the mixed gas to be supplied to the internal combustion engine is subjected to estimation is performed. For example, a sensor using stabilized zirconia is used as an oxygen sensor as described in Japanese Laid-Open Patent Publication No. JP-A-2006-170938.

However, in the above oxygen sensor, the internal resistance is extremely increased at a low temperature state. Therefore, even when the air-fuel ratio is the same between the low temperature state and the high temperature state, the output of the oxygen sensor from the low temperature state can be different from the output of the oxygen sensor of the high temperature state. Specifically, in the low temperature state, the oxygen sensor can output a value according to an oxygen concentration different from the actual oxygen concentration. Therefore, it is difficult herein to appropriately control the air-fuel ratio when performing feedback control on the air-fuel ratio using the output value from the oxygen sensor. The output value from the oxygen sensor herein is converged to a predetermined convergence value in the deactivated state. Accordingly, the well-known decision device is configured to determine if the output value from the oxygen sensor falls within a predetermined deactivation range including the convergence value to determine if the oxygen sensor is in a deactivated state. When it is determined that the oxygen sensor is in the deactivated state, the feedback control using the output value from the oxygen sensor is configured to stop. Thereby it is possible to avoid performing an inappropriate control for the actual conditions of the internal combustion engine.

The oxygen sensor is configured to output a value indicative of a lean state when a fuel supply cutoff is performed during control of the internal combustion engine. Subsequently, when the temperature of the oxygen sensor is lowered in conjunction with the temperature of the internal combustion engine, the output value from the oxygen sensor converges to the above convergence value. In this case, depending on the setting of the deactivation range, the oxygen sensor can be deactivated before the output value from the oxygen sensor reaches the above deactivation range. However, the aforementioned deactivation state of the oxygen sensor cannot be appropriately determined by a well-known method of determining whether or not the output value from the oxygen sensor falls within the deactivation range. In view of this, it is possible to assume a method of determining the deactivation state of the oxygen sensor and stopping the feedback control immediately after the execution of the fuel supply cutoff. However, in this method, the feedback control is actually stopped when the oxygen sensor is in an active state. Therefore, exhaust gas deterioration can be caused unnecessarily.

An object of the present invention is to provide an activity determination system for an oxygen sensor for appropriately determining the deactivation state of the oxygen sensor and simultaneously for suppressing exhaust gas degradation.

An activity determination system for an oxygen sensor according to an aspect of the present invention includes an oxygen sensor, a signal processing circuit, a deactivation determination zone, and a fuel supply cutoff determination zone. The oxygen sensor is configured to output a signal based on the concentration of oxygen in the exhaust from the internal combustion engine when the oxygen sensor is in an active state. The signal processing circuit is configured to receive a signal input thereto from an oxygen sensor. The signal processing circuit is configured to output a signal based on a signal input thereto from the oxygen sensor when the oxygen sensor is in an active state. The signal processing circuit is configured to output a signal that converges to a predetermined lean output value when the oxygen sensor is active and the oxygen sensor atmosphere is maintained in the same state as the standard atmosphere. The signal processing circuit is configured to output a signal that converges to a predetermined convergence value that is different from the lean output value when the oxygen sensor is maintained in the deactivated state. The deactivation determination zone is configured to determine that the oxygen sensor is in a deactivated state when the output value from the signal processing circuit falls within a predetermined deactivation range including the convergence value. The fuel supply cutoff determination zone is configured to determine whether a fuel supply cutoff is currently performed in the internal combustion engine. Additionally, the deactivation determination zone is configured to change when the output value from the signal processing circuit changes toward the convergence value during a predetermined time period or longer during execution of the fuel supply cutoff or during execution of the fuel supply cutoff The oxygen sensor is determined to be in a deactivated state when the output value from the signal processing circuit changes by a predetermined amount or more toward the convergence value.

Advantageous effects of the invention

According to the above aspect of the invention, the activity determination system for an oxygen sensor, the deactivation determination zone is configured to determine the oxygen sensing based on the amount of change or the time period of the change from the output value of the signal processing circuit. The deactivated state of the device. During execution of the fuel supply cutoff, for example, the oxygen sensor atmosphere enters a state having a large partial pressure of oxygen as seen in a standard atmosphere. Thus, during execution of the fuel supply cutoff, when the oxygen sensor is in an active state, the output value from the signal processing circuit does not exceed a predetermined range indicative of a lean state. Therefore, it is possible to appropriately determine that the oxygen sensor is in a deactivated state by detecting that the output value from the signal processing circuit changes toward the convergence value. In addition, it is possible to reduce the oxygen sensor from being determined to be in a deactivated state (even if it is actually in an active state) as compared to a configuration in which it is determined that the oxygen sensor is in a deactivated state immediately after execution of the fuel supply cutoff. Time period. Therefore, it is possible to perform control using the output from the oxygen sensor as long as possible. Exhaust gas degradation can thereby be suppressed.

Reference is now made to the accompanying drawings which form a part of this original disclosure.

An exemplary embodiment of the invention will be explained hereinafter with reference to the drawings. 1 is a side view of a locomotive 1 as a straddle type vehicle, in accordance with an exemplary embodiment of the present invention. It should be noted that the cross-shaped arrows in the drawings indicate the respective directions. The reference numbers "F", "Rr", "U", "Lo", "R" and "L" which are attached to the arrows refer to "before", "after", "up", "down" and "right" respectively. And the "left" direction. In addition, it should be noted in the present exemplary embodiment that the front, rear, right, left, up, and down directions respectively refer to the directions seen by the rider seated on the seat 5.

The locomotive 1 has a scooter type. The locomotive 1 includes a vehicle frame 2 and a power unit 3. This power unit 3 is attached to the vehicle frame 2 . Specifically, the power unit 3 is attached to the vehicle frame 2 while being pivotable up and down. The seat 5 is placed above the power unit 3 for allowing the rider to sit on it. The handle unit 6 and the front wheel 7 are placed in front of the seat 5. A footrest 8 is disposed between the seat 5 and the handle unit 6 for allowing the rider to place his or her foot thereon. The rear wheel 9 is placed below the seat 5. The rear buffer unit 10 is disposed between the power unit 3 and the vehicle frame 2.

The power unit 3 includes an engine 11 and a power transmission member 12. The engine 11 corresponds to the internal combustion engine of the present invention. The rear wheel 9 is rotatably attached to a rear portion of the power transmission member 12. The driving force generated in the engine 11 is transmitted to the rear wheel 9 via the power transmission member 12.

2 is a side view of the power unit 3 and the rear wheel 9. The rear wheel 9 is disposed behind the engine 11. The rear wheel 9 is positioned for alignment with the power transmission member 12 in the lateral (i.e., left-right) direction of the locomotive 1. The engine 11 includes a crankcase 13 , a cylinder block 14 , a cylinder head 15 , and a cylinder head cover 16 . The cylinder block 14 is attached to the crank axle box 13. The cylinder block 14 is disposed in front of the crankcase 13. The cylinder head 15 is attached to the cylinder block 14. The cylinder head 15 is disposed in front of the cylinder block 14. A cylinder head cover 16 is attached to the cylinder head 15. The cylinder head cover 16 is disposed in front of the cylinder head 15. An intake duct 21 is coupled to the top surface of the cylinder head 15. An air cleaner 22 is connected to the intake duct 21. The intake duct 21 forms an intake path 31 (see Fig. 4) to be described. Air is supplied to the combustion chamber of the engine 11 via the intake duct 21. In addition, the cylinder head 15 includes an exhaust port 23 on its bottom surface. The exhaust port 23 projects downward from the bottom surface of the cylinder head 15. The exhaust duct 24 is connected to the exhaust port 23. The muffler 25 is connected to the exhaust duct 24. The exhaust port 23 and the exhaust duct 24 form an exhaust path 36 (see Fig. 4) to be described. Exhaust gases are exhausted from the combustion chamber of the engine 11 via an exhaust conduit 24.

In FIGS. 1 and 2, the dotted line A is the cylinder axis of the engine 11. The cylinder axis A is inclined forward and upward in the longitudinal (front-rear) direction of the locomotive 1. It should be noted that each of the angles formed by the cylinder axis A and the longitudinal direction of the locomotive 1 is not limited to a specific angle. For example, the angle of inclination of the cylinder axis A with respect to the longitudinal direction of the locomotive 1 may be 0 degrees. In other words, the cylinder axis A can overlap with the longitudinal direction of the locomotive 1.

3 is a front elevational view of the vehicle frame 2, the power unit 3, and the rear wheel 9 as seen from the front side of the cylinder axis A. The vehicle frame 2 includes a pair of left side frames 2a and right side frames 2b. The left frame 2a and the right frame 2b are disposed at a predetermined interval in the lateral direction. As illustrated in Figures 1 and 2, the shelves 2a and 2b extend rearwardly and upwardly in a side view. In addition, the shelves 2a and 2b intersect the engine 11 in a side view. As illustrated in FIG. 3, the power transmission member 12 is disposed on the left side of the engine 11. Further, the power transmission member 12 is disposed behind the frames 2a and 2b. The crankcase 13 is placed behind the frames 2a and 2b. The rear wheel 9 is disposed behind the engine 11. As seen from the front side of the cylinder axis A, the cylinder block 14, cylinder head 15 and cylinder head cover 16 are laterally disposed between the brackets 2a and 2b herein for allowing the power unit 3 to be undisturbed by the racks 2a and 2b. Bottom up and down. Additionally, an oxygen sensor 40 to be described is attached to the cylinder head 15. The oxygen sensor 40 is configured to detect the concentration of oxygen in the exhaust gas to be exhausted from the combustion chamber of the engine 11. Specifically, the oxygen sensor 40 is attached to the exhaust port 23 of the cylinder head 15.

4 is a configuration diagram of a control system of the engine 11 and the engine 11. As illustrated in FIG. 4, the engine 11 includes a piston 26, a crankshaft 27, and a connecting rod (connecting rod) 28. Piston 26 is movably disposed within cylinder block 14. The crankshaft 27 is rotatably disposed within the crankcase 13 described above. The connecting rod 28 is coupled to the piston 26 and the crank shaft 27.

Further, the engine 11 includes a fuel injection valve 32, an ignition device 33, an intake valve 34, and an exhaust valve 35. Fuel injection valve 32 is configured to supply fuel to combustion chamber 29 within cylinder head 15 . In the present exemplary embodiment, fuel injection valve 32 is positioned for injecting fuel into intake passage 31. It should be noted that the fuel injection valve 32 may be disposed for injecting fuel into the combustion chamber 29. The fuel injection valve 32 is connected to the fuel tank 38 via a fuel conduit 37. The fuel tank 38 includes a fuel pump 39 and a fuel sensor 46 therein. Fuel pump 39 is configured to supply fuel to fuel conduit 37. Fuel sensor 46 is configured to detect the amount of fuel contained in fuel tank 38. The ignition device 33 is configured to ignite the fuel contained in the combustion chamber 29. The engine 11 includes a rotational speed sensor 41 and an engine temperature sensor 42. The rotational speed sensor 41 is configured to detect the rotational speed of the crankshaft 27 for detecting engine speed. The engine temperature sensor 42 is configured to detect the temperature of the engine 11. It should be noted that the engine temperature sensor 42 can be configured to detect the temperature of a portion (eg, a cylinder) of the engine 11. When the engine 11 is of the water-cooled type, the engine temperature sensor 42 may alternatively be configured to detect the temperature of the coolant of the engine 11. In other words, the engine temperature sensor 42 can be configured to directly detect the temperature of the engine 11. Alternatively, engine temperature sensor 42 may be configured to indirectly detect the temperature of engine 11 via detecting the temperature of the coolant or the like. Intake valve 34 is configured to be opened or closed for connecting or disconnecting intake passage 31 and combustion chamber 29. On the other hand, the exhaust valve 35 is configured to be opened or closed for connecting or disconnecting the combustion chamber 29 and the exhaust path 36.

The intake path 31 is provided with an intake air temperature sensor 43 and an intake pressure sensor 44. The intake air temperature sensor 43 is configured to detect the temperature of the air to be drawn into the combustion chamber 29 via the intake path 31. The intake pressure sensor 44 is configured to detect an intake pressure that is an internal pressure of the intake path 31. Further, the intake passage 31 is provided with a throttle valve 51. The degree of opening of the throttle valve 51 is configured to be adjusted for adjusting the amount of air to be supplied to the combustion chamber 29 via the intake path 31. The throttle valve 51 is provided with a throttle position sensor 45 (see Fig. 5). The throttle position sensor 45 is configured to detect the degree of opening of the throttle valve 51 (hereinafter referred to as "throttle opening degree").

The exhaust path 36 is provided with a catalyst 52. Further, the exhaust path 36 is provided with an oxygen sensor 40 (described above) as an air-fuel ratio sensor. The oxygen sensor 40 can detect which of the rich or lean state the mixed gas is in. The surplus state herein refers to a state in which the air-fuel ratio of the mixed gas is less than its theoretical air-fuel ratio. In contrast, a lean state herein refers to a state in which the air-fuel ratio of the mixed gas is greater than its theoretical air-fuel ratio. The oxygen sensor 40 will be described in detail in the following paragraphs.

The locomotive 1 includes an ECU (Power Control Unit) 60 that is configured to control the engine 11. FIG. 5 is a block diagram of the configuration of the ECU 60. The ECU 60 includes a calculation portion 61, a storage portion 62, an input portion 63, and an output portion 64. The calculation portion 61 includes, for example, a CPU and is configured to perform various calculation processes for the control to be described. The storage portion 62 includes memory devices such as ROM and RAM and is configured to store a variety of information and control programs for performing the control to be described. Each of the input portion 63 and the output portion 64 includes an interface circuit. The various sensors 40 to 46 described above are connected to the input portion 63. Input portion 63 is configured to receive a detection signal from each of sensors 40-46. Specifically, the sensor connected to the input portion 63 includes a rotational speed sensor 41, an engine temperature sensor 42, an intake air temperature sensor 43, an intake pressure sensor 44, and a throttle position sensor. 45. Oxygen sensor 40 and fuel sensor 46. On the other hand, the fuel injection valve 32 and the ignition device 33 are connected to the output portion 64. The output portion 64 is configured to output a command signal to the fuel injection valve 32 and the ignition device 33 based on the result of the calculation process performed by the calculation portion 61.

The ECU 60 is configured to perform various controls, such as control of the amount of fuel to be injected from the fuel injection valve 32 and control of the timing of ignition by the ignition device 33 based on signals from the respective sensors 40-46. In particular, ECU 60 is configured to correct the time period during which fuel injection valve 32 is opened based on signals from oxygen sensor 40. Therefore, feedback control is performed for the air-fuel ratio of the mixed gas to obtain a desired air-fuel ratio. It should be noted that when the temperature of the solid electrolyte element in the oxygen sensor 40 is low, the detection accuracy of the oxygen sensor 40 is deteriorated. In other words, when the temperature of the oxygen sensor 40 is low, the oxygen sensor 40 is in a deactivated state and its detection reliability is lowered. In contrast, when the temperature of the oxygen sensor 40 is sufficiently high, the oxygen sensor 40 is in an active state and its detection reliability is improved. It is difficult to accurately control the air-fuel ratio when the feedback control is performed on the air-fuel ratio of the mixed gas based on the signal from the oxygen sensor 40 under the condition that the oxygen sensor 40 is in the deactivated state. In view of the above, the ECU 60 is first configured to determine which of the active state and the deactivated state the oxygen sensor 40 is in. When it is determined that the oxygen sensor 40 is in an active state, the ECU 60 is configured to perform the feedback control described above. In contrast, when it is determined that the oxygen sensor 40 is in the deactivated state, the ECU 60 is configured not to perform the above-described feedback control, but based on the fuel injection control amount initially stored in the storage portion 62 to the fuel injection valve 32. Perform feedforward control. The following explanation relates to an activity determination system for the oxygen sensor 40, that is, a system for determining which of the deactivated state and the active state the oxygen sensor 40 is in. The activity determination system for the oxygen sensor 40 includes an oxygen sensor 40, a fuel supply cutoff determination zone 65, a deactivation determination zone 66, and a lean/surplus determination zone 67.

Oxygen sensor 40 is a sensor that uses a solid electrolyte made of, for example, stabilized zirconia. In the active state, the oxygen sensor 40 is configured to output a signal having a voltage value based on the concentration of oxygen in the exhaust. FIG. 6 is a schematic configuration diagram of the oxygen sensor 40 and the input portion 63. As shown in FIG. 6, input portion 63 includes a signal processing circuit 68 to be coupled to oxygen sensor 40. Signal processing circuit 68 is configured to receive signals from oxygen sensor 40. The signal processing circuit 68 is a pull-up circuit and includes an input line 69 and a pull-up resistor R1. The input line 69 connects the oxygen sensor 40 and the calculation portion 61. The input line 69 is connected to the power supply Vcc, and the pull-up resistor R1 is disposed between the power supply Vcc and the input line 69.

FIG. 7 shows the output characteristics of the signal to be output from the signal processing circuit 68 to the calculation portion 61. In the diagram of Fig. 7, the vertical axis represents the output value (voltage) from the signal processing circuit 68, and the horizontal axis represents time. The solid line L1 represents the signal to be output from the signal processing circuit 68 when the oxygen sensor 40 is in an active state. Signal processing circuit 68 is configured to output a signal to computing portion 61 based on the signal input thereto from oxygen sensor 40 when oxygen sensor 40 is in an active state. The oxygen sensor 40 is a binary sensor. The binary oxygen sensor has a type in which the output value is extremely changed when the margin state is changed to the lean state and the lean state is changed to the margin state. As represented by solid line L1 in FIG. 7, signal processing circuit 68 is configured to output a signal having an output value that converges toward a predetermined margin output value VR when the mixed gas is in a rich state. In contrast, signal processing circuit 68 is configured to output a signal having an output value that converges toward a predetermined lean output value VL when the mixed gas is in a lean state. Thus, signal processing circuit 68 is configured to output a convergence to a lean output value VL when oxygen sensor 40 is active and the atmosphere of oxygen sensor 40 is maintained at the same time as the standard atmosphere. The signal of the output value. In the oxygen sensor 40 of the present exemplary embodiment, the surplus output value VR is greater than the lean output value VL. For example, the lean output value VL is 0 volts.

In FIG. 7, a broken line L2 indicates a signal to be output from the signal processing circuit 68 when the oxygen sensor 40 is in a deactivated state. As represented by the dashed line L2, the signal processing circuit 68 is configured to output a signal having an output value that converges to a predetermined convergence value VP when the oxygen sensor 40 is in a deactivated state. As described above, the signal processing circuit 68 is a pull-up circuit. When the oxygen sensor 40 is in the deactivated state, the internal resistance R0 of the oxygen sensor 40 is locally maximized. Signal processing circuit 68 is configured herein to output a signal having a predetermined pull-up voltage to be generated by pull-up resistor R1 and power supply Vcc in signal processing circuit 68. Thus, when the oxygen sensor 40 is in the deactivated state, the output value from the signal processing circuit 68 converges to a predetermined pull-up voltage greater than 0 volts. The above convergence value VP therefore corresponds to the pull-up voltage. The pull-up voltage is an intermediate value between the lean output value VL and the surplus output value VR. In the present exemplary embodiment, the pull-up voltage is greater than the lean output value VL and less than the rich output value VR. In other words, the convergence value VP is different from the lean output value VL. The oxygen sensor 40 is herein a so-called heaterless type sensor and is not equipped with a heater for heating the above elements. Therefore, the exhaust gas from the engine 11 acts as a heat source for heating the elements of the oxygen sensor 40. Therefore, when the temperature of the exhaust gas from the engine 11 is lowered, the oxygen sensor 40 is in a deactivated state. When the oxygen sensor 40 is in the deactivated state, the output value from the signal processing circuit 68 converges toward the convergence value VP.

As shown in FIG. 5, the lean/surplus determination zone 67, the fuel supply cutoff determination zone 65, and the deactivation determination zone 66 are included in the above-described calculation section 61. In other words, the calculation portion 61 is configured to perform the function as the lean/surplus determination area 67, the function as the fuel supply cutoff determination area 65, and the function as the deactivation determination area 66.

The fuel supply cutoff determination zone 65 is configured to determine whether a fuel supply cutoff is currently performed for the engine 11. For example, the fuel supply cutoff determination zone 65 is configured to determine whether a fuel supply cutoff is currently being performed for the engine 11 based on a command signal to the fuel injection valve 32. Alternatively, the fuel supply cutoff determination zone 65 can be configured to determine whether a fuel supply cutoff is currently being performed for the engine 11 based on the engine speed and the degree of throttle opening. It should be noted that the fuel supply cutoff is configured to be performed when one or a plurality of predetermined conditions for performing the fuel supply cutoff are satisfied during the travel of the locomotive 1. An exemplary condition for performing a fuel supply cutoff is that the engine speed becomes greater than or equal to a predetermined speed and at the same time the throttle opening degree is less than or equal to a predetermined degree of opening. In contrast, when the single or plural predetermined conditions for stopping the fuel supply cutoff are satisfied during the execution of the fuel supply cutoff, the fuel supply cutoff is stopped and the normal operation is performed again. An exemplary condition for stopping the fuel supply cutoff is that the engine speed becomes less than or equal to a predetermined speed. Therefore, prevent the engine from stalling. Alternatively, one exemplary condition for stopping the fuel supply cutoff may be that the degree of throttling opening becomes greater than or equal to a predetermined level. Therefore, the fuel supply cutoff can be stopped in response to the rider's acceleration demand.

Deactivation determination zone 66 is configured to determine oxygen sensing when output from signal processing circuit 68 falls within a predetermined deactivation range during execution of normal operation (i.e., during non-execution of fuel supply cutoff) The device 40 is in a deactivated state. As shown in FIG. 7, the predetermined deactivation range Rna includes the above-described convergence value VP. The deactivation determination zone 66 is configured to determine the oxygen sensor 40 when the output value from the signal processing circuit 68 falls within the deactivation range Rna for a predetermined period of time or longer during non-execution of the fuel supply cutoff period. In a state of being deactivated. The appropriate time period for determining the deactivated state of the oxygen sensor 40 has been initially obtained by experimentation, simulation, and/or the like, and is set herein as a predetermined time period. The predetermined deactivation range Rna is a range between the first activity determination value V1 and the second activity determination value V2. The first activity determination value V1 is an intermediate value between the lean output value VL and the convergence value VP. In the present exemplary embodiment, the first activity determination value V1 is greater than the lean output value VL and less than the convergence value VP. The second activity determination value V2 is an intermediate value between the margin output value VR and the convergence value VP. In the present exemplary embodiment, the second activity determination value V2 is smaller than the rich output value VR and greater than the convergence value VP. Further, the second activity determination value V2 is larger than the first activity determination value V1. Appropriate values for accurately determining whether the oxygen sensor 40 is in a deactivated state have been initially obtained by experiments, simulations, and/or the like, and are set herein as the first activity determination value V1 and the second activity. Each of the values V2 is determined. The deactivation determination zone 66 is configured to determine that the oxygen sensor 40 is in a deactivated state when the output value from the signal processing circuit 68 is greater than or equal to the first activity determination value V1 and simultaneously less than or equal to the second activity determination value V2. For example, in a low temperature environment or when the engine 11 is idle while its temperature is lowered due to rain, the temperature of the exhaust gas is lowered. In such cases, the temperature of the oxygen sensor 40 decreases and even enters a deactivated state during non-execution of the fuel supply cutoff. It should be noted that the range between the lean output value VL and the first activity determination value V1 will hereinafter be referred to as "first active range Ra1". Further, the above range between the surplus output value VR and the second activity determination value V2 will hereinafter be referred to as "second activity range Ra2". The deactivation range Rna is set between the first active range Ra1 and the second active range Ra2. The deactivation determination zone 66 is configured to determine that the oxygen sensor 40 is in an output when the output value from the signal processing circuit 68 falls within the first active range Ra1 for a predetermined period of time or longer during execution of normal operation. Active state. Additionally, the deactivation determination zone 66 is configured to determine the oxygen sensor when the output value from the signal processing circuit 68 falls within the second active range Ra2 for a predetermined period of time or longer during execution of normal operation. 40 is in an active state. The appropriate time period for determining the active state of the oxygen sensor 40 has been initially obtained by experimentation, simulation, and/or the like, and is set herein as a predetermined time period.

The lean/rich decision area 67 is configured to compare the output value from the signal processing circuit 68 with a predetermined decision threshold VA under conditions that the oxygen sensor 40 is determined to be in an active state to determine that the mixed gas is poor Which of the state and the surplus state. In particular, the lean/surplus decision zone 67 is configured to determine the mix when the output value from the signal processing circuit 68 is less than or equal to the predetermined decision threshold VA under the condition that the oxygen sensor 40 is determined to be in an active state. The gas is in a state of poverty. In contrast, the lean/rich decision area 67 is configured to be when the output value from the oxygen sensor 40 is greater than or equal to the predetermined decision threshold VA when the oxygen sensor 40 is determined to be in an active state. It is determined that the mixed gas of the engine 11 is in a surplus state. The determination threshold VA is an intermediate value between the first active range Ra1 and the second active range Ra2. Therefore, it is determined that the threshold value VA falls in the deactivation range Rna.

The deactivation determination area 66 is configured to perform the deactivation determination process shown in FIG. 8 when the fuel supply cutoff determination area 65 determines that the fuel supply cutoff of the currently executed engine 11 is OFF.

First, in step S1, the output value Vd(n) from the signal processing circuit 68 (hereinafter simply referred to as "output value Vd(n)") is loaded in the deactivation determination area 66. The loading of the output value Vd(n) is configured to repeat in a predetermined cycle, as described below. For example, the output value Vd(n) is configured to be loaded with a loop for performing calculations for feedback control based on the output value Vd(n). It should be noted that "n" represents the frequency of calculations performed for feedback control. Specifically, "n" is set to 1 in the first calculation. Similarly, "n" is set to 2 in the second calculation. FIG. 9 is an exemplary timing chart showing changes in the output value Vd(n) when the fuel supply cutoff is performed. In the time period from the time point t0 to the time point t1, the oxygen sensor 40 is in an active state, and the mixed gas is in a surplus state. Therefore, the output value Vd(n) falls in the second active range Ra2. When the fuel supply cutoff is performed at the time point t1, the atmosphere of the oxygen sensor 40 becomes similar to the standard atmosphere having a large oxygen partial pressure. In other words, when the fuel supply cutoff is performed, the atmosphere of the oxygen sensor 40 becomes a lean state. Therefore, at time point t1 and thereafter, the output value Vd(n) decreases and falls in the first active range Ra1.

Next, in step S2, it is determined whether or not the output value Vd(n) is smaller than the bottom output value Vbottom. When the output value Vd(n) is smaller than the bottom output value Vbottom, the process proceeds to step S3. In step S3, the output value Vd(n) is set as the bottom output value. Processing then returns to step S1. It should be noted that, in the case where steps S2 and S3 are not performed, the output value Vd(n) is set to the bottom output value Vbottom in the first calculation. Through the processing of steps S1 to S3, when the output value Vd(n) as shown in FIG. 9 is continuously decreased after starting the fuel supply cutoff (from time point t1 to time point t2), the bottom output value Vbottom is updated to the newest The output value of the load is Vd(n).

On the other hand, when it is determined in step S2 that the output value Vd(n) is greater than or equal to the bottom output value Vbottom, the processing proceeds to step S4. As shown in FIG. 9, after the start of the fuel supply cutoff, the output value Vd(n) is reduced to a minimum value (at time point t2) herein. In other words, the output value Vd(n) reaches the lean output value VL. Next, the minimum value of the output value Vd(n) is set as the bottom output value Vbottom. In Fig. 9, the minimum value of the output value Vd(n) is equal to the lean output value VL. However, the minimum value of the output value Vd(n) may be greater than the lean output value VL.

In step S4, it is determined whether the difference between the output value Vd(n) and the bottom output value Vbottom is greater than or equal to a predetermined threshold value Vth. As shown in FIG. 9, it is determined herein whether or not the amount of increase dV from the minimum value of the output value Vd(n) is greater than or equal to the predetermined threshold value Vth. When the difference between the output value Vd(n) and the bottom output value Vbottom is not greater than or equal to the predetermined threshold value Vth, the process returns to step S1. On the other hand, when the difference between the output value Vd(n) and the bottom output value Vbottom is greater than or equal to the predetermined threshold value Vth, the process proceeds to step S5. In step S5, it is determined that the oxygen sensor 40 is in a deactivated state. Specifically, when the increase amount dV from the minimum value of the output value Vd(n) as shown in FIG. 9 becomes greater than or equal to the predetermined threshold value Vth (at the time point t3), it is determined that the oxygen sensor 40 is at Go live. That is, when the output value Vd(n) changes toward the convergence value VP by a predetermined amount or more during execution of the fuel supply cutoff, it is determined that the oxygen sensor 40 is in a deactivated state. In other words, when the output value Vd(n) changes from the value which deviates most from the convergence value VP during the execution of the fuel supply cutoff to the convergence value VP by a predetermined amount or more, it is determined that the oxygen sensor 40 is in the deactivated state. Further, in other words, when the output value Vd(n) changes from a value (as a turning point of the trend from the deviation convergence value VP to a tendency to converge to the convergence value VP) during execution of the fuel supply cutoff, the convergence value VP is changed by a predetermined amount or When a larger amount is made, it is determined that the oxygen sensor 40 is in a deactivated state. It should be noted that the value for appropriately determining the oxygen sensor 40 to enter the deactivated state during execution of the fuel supply cutoff has been initially obtained by experiments, simulations, and/or the like, and is set herein as predetermined Limit value Vth. The predetermined threshold value Vth is smaller than the first activity determination value V1. In other words, the predetermined threshold value Vth is an intermediate value between the lean output value VL and the first activity determination value V1. It should be noted that the output value Vd(n) and the bottom output value Vbottom are configured to be reset at the end of the fuel supply cutoff.

The activity determination system for the oxygen sensor 40 according to the present exemplary embodiment has the following features.

The deactivation determination zone 66 is configured to determine the deactivation state of the oxygen sensor 40 based on the amount of increase dV from the minimum value of the output value Vd(n) after the start of the fuel supply cutoff. When the oxygen sensor 40 is in an active state during execution of the fuel supply cutoff, the output value Vd(n) does not increase from the minimum value. In other words, when the oxygen sensor 40 is in the active state, a signal having the thus increased output value Vd(n) is not continuously output during execution of the fuel supply cutoff. Therefore, it is possible to appropriately determine that the oxygen sensor 40 is in the deactivated state by detecting that the output value Vd(n) increases toward the convergence value VP. In addition, the feedback control can be performed as long as possible in comparison with the configuration in which the deactivated state of the oxygen sensor 40 is determined and the feedback control is stopped immediately after the execution of the fuel supply cutoff. Exhaust gas degradation can thereby be suppressed. Still further, the cost increase can be suppressed herein as compared to a structure in which a device such as an operational amplifier is added to the input portion 63 of the ECU 60 to enhance the accuracy of the activity determination for the oxygen sensor 40.

There is a difference between the deactivation determination method for the oxygen sensor 40 during the execution of the normal operation and the deactivation determination method for the oxygen sensor 40 during the execution of the fuel supply cutoff. Specifically, the predetermined threshold value Vth to be used for the determination during the execution of the fuel supply cutoff is an intermediate value between the lean output value VL and the first activity determination value V1. Therefore, compared with the configuration in which the same threshold value is used for the deactivation determination during the execution of the normal control and the deactivation determination during the execution of the fuel supply cutoff, it is possible that during the execution of the fuel supply cutoff The oxygen sensor 40 is determined to be in a deactivated state at an earlier stage in which the oxygen sensor 40 may be in a deactivated condition. In particular, the fuel supply cutoff can be performed during the travel of the locomotive 1. In this case, the deactivation determination for the oxygen sensor 40 can be performed well in advance during the travel of the locomotive 1 because the oxygen sensor 40 is determined at an early stage during the execution of the fuel supply cutoff as described above. Go live. On the other hand, it is often determined that the oxygen sensor 40 is in a deactivated state during execution of normal operation when the engine 11 is idle. In contrast, the fuel supply cutoff can be performed during travel of the vehicle. Therefore, it can be determined that the oxygen sensor 40 is in a deactivated state during travel of the vehicle due to execution of the fuel supply cutoff.

Signal processing circuit 68 is a pull up circuit. Therefore, when the oxygen sensor 40 is in the deactivated state, the output value Vd(n) converges toward the convergence value VP. It is possible to appropriately determine that the oxygen sensor 40 is in a deactivated state by detecting this change in the output value Vd(n).

The oxygen sensor 40 is a binary sensor. Therefore, when the oxygen sensor 40 is in an active state during execution of the fuel supply cutoff, the output value Vd(n) does not increase from the minimum value after the start of the fuel supply cutoff. Therefore, it is possible to appropriately determine that the oxygen sensor 40 is in a deactivated state (as described above) by detecting a change in the output value Vd(n).

In the heaterless type oxygen sensor 40, the temperature of the element tends to decrease during execution of the fuel supply cutoff. Therefore, the present invention is particularly effective for the heaterless type oxygen sensor 40.

Illustrative embodiments of the invention have been explained above. The present invention is not limited to the above-described exemplary embodiments, and various changes can be made herein without departing from the scope of the invention.

The straddle type vehicle is not limited to the above locomotive, but may be other vehicles such as an all terrain vehicle or a motorized sleigh. In addition, the locomotive is not limited to the above scooter, and may be other locomotives such as a light motorcycle or a sports locomotive.

In the above exemplary embodiment, the lean output value VL is smaller than the rich output value VR. However, as shown in FIG. 10, the lean output value VL may be greater than the rich output value VR. In other words, the output value Vd(n) of the above exemplary embodiment can be vertically reversed herein. In this case, when the amount of decrease dV from the minimum value of the output value Vd(n) becomes greater than the predetermined threshold value Vth, it is determined that the oxygen sensor 40 is in the deactivated state.

The signal processing circuit 68 is not limited to the pull-up circuit, and may be a pull-down circuit as shown in FIG. Specifically, the signal processing circuit 68 shown in FIG. 11 includes an input line 69 and a pull-down resistor R2. The input line 69 connects the oxygen sensor 40 and the calculation portion 61. The input line 69 is connected to the ground G, and the pull-down resistor R2 is disposed between the ground G and the input line 69. When the oxygen sensor 40 is in the deactivated state, the output value Vd(n) from the signal processing circuit 68 converges to 0 V. In other words, the predetermined convergence value of the present invention is set to 0 V herein. In other words, the poor output value VL is required to be different from 0 V in this paper. This is because the deactivated state of the oxygen sensor 40 is determined by the change in the output value Vd(n) from the lean output value VL to the convergence value VP.

The oxygen sensor 40 is not limited to a binary sensor and may be a line sensor. In particular, the oxygen sensor 40 can be a type of sensor configured to linearly output a value based on the oxygen concentration in the active state. The signal processing circuit 68 can be integrated with the oxygen sensor 40 and is not included in the input portion 63 of the ECU 60.

In the above-described activity determination shown in FIG. 8, the smoothing process can be performed for the loaded output value Vd(n). The smoothing process herein refers to a process of averaging the output values Vd(n).

In the above exemplary embodiment, the deactivation determination area 66 is configured to determine oxygen sensing when the increase amount dV of the output value Vd(n) becomes greater than or equal to the predetermined threshold value Vth during execution of the fuel supply cutoff. The device 40 is in a deactivated state. However, the deactivation determination zone 66 can be configured to determine that the oxygen sensor 40 is in a deactivated state when the output value Vd(n) continuously increases during execution of the fuel supply cutoff for a predetermined period of time or longer. In particular, as shown in FIG. 12, the deactivation determination zone 66 can be configured to determine the oxygen sensor when the continuously increasing time period dt of the output value Vd(n) becomes a predetermined time period or longer. 40 is in a state of deactivation. Fig. 13 is a flow chart showing the deactivation determination processing corresponding to the above configuration.

First, in step S10, the variable Tm is reset to zero. The variable Tm represents the frequency at which the increase in the output value Vd(n) is continuously detected, as described in the following paragraphs.

Steps S11 to S13 are the same as steps S1 to S3 in the above-described exemplary embodiment. In short, it is detected that the output value Vd(n) reaches a minimum value after the start of the fuel supply cutoff.

Next, in step S14, it is determined whether or not the output value Vd(n) is greater than a previously detected output value Vd(n-1). When the output value Vd(n) is greater than the previously detected output value Vd(n-1), the process proceeds to step S15. In step S15, 1 is added to the variable Tm. After the output value Vd(n) reaches a minimum value, the frequency of the continuously detected output value Vd(n) is counted herein.

Next, in step S16, it is determined whether the variable Tm is greater than or equal to a predetermined threshold value Tth. When the variable Tm is not greater than or equal to the predetermined threshold value Tth, the process proceeds to step S11 and the output value Vd(n) is loaded again. Referring again to step S14, when it is determined that the output value Vd(n) is not greater than the previously detected output value Vd(n-1), the process returns to step S10 and the variable Tm is reset to zero.

When it is determined in step S16 that the variable Tm is greater than or equal to the predetermined threshold value Tth, the process proceeds to step S17. In step S17, it is determined that the oxygen sensor 40 is in a deactivated state. In other words, when the frequency of the continuously detected output value Vd(n) increases becomes greater than or equal to the predetermined threshold value Tth, it is determined that the oxygen sensor 40 is in the deactivated state. It should be noted that the value for appropriately determining the oxygen sensor 40 to enter the deactivated state during execution of the fuel supply cutoff has been initially obtained by experiments, simulations, and/or the like, and is set herein as predetermined Limit value Tth.

As shown in FIG. 12, via the above-described deactivation determination processing, when the time value dt of the continuous increase of the output value Vd(n) from the lean output value VL becomes greater than or equal to the predetermined time period, it is determined that the oxygen sensor 40 is at Go live. That is, the deactivation determination zone 66 can be configured to determine the oxygen sensor 40 when the output value Vd(n) continuously changes toward the convergence value VP during a predetermined period of time or longer during execution of the fuel supply cutoff. In a state of being deactivated. In other words, the deactivation determination zone 66 can be configured to output the value Vd(n) from a value that deviates most from the convergence value VP to a convergence value VP during execution of the fuel supply cutoff for a predetermined period of time or longer. The oxygen sensor 40 is determined to be in a deactivated state when continuously changing. Further in other words, the deactivation determination zone 66 can be configured to output a value Vd(n) from a value during a predetermined period of time or longer during execution of the fuel supply cutoff (as a trend of the self-offset convergence value VP to The oxygen sensor 40 is determined to be in a deactivated state when the convergence value VP is continuously changed toward the turning point of the tendency of the convergence value VP.

In the deactivation determination processing shown in Fig. 13, the frequency of the continuously detected output value Vd(n) is used as information for indicating the time period of the continuous increase of the output value Vd(n). However, a timer can be configured to directly count the successive increase in the output value Vd(n) for a period of time.

In the deactivation determination process shown in Fig. 13, the output value Vd(n) can be vertically reversed as shown in Fig. 14. In this case, when the output value Vd(n) changes from the continuously decreasing time period dt of the maximum value to a predetermined time period or longer, it is determined that the oxygen sensor 40 is in the deactivated state.

In the above exemplary embodiment, the monitoring of the increase in the output value Vd(n) begins with the execution of the start fuel supply cutoff. However, monitoring of the increase in the output value Vd(n) may begin after a predetermined period of time has elapsed since the start of the fuel supply cutoff. As indicated in Fig. 15, for example, the above determination of the deactivation state of the oxygen sensor can be started after a predetermined time period dt has elapsed from the time point t1 corresponding to the start of the execution of the fuel supply cutoff. Even when a signal indicating a surplus state is output immediately after the start of the fuel supply cutoff (despite the lack of fuel injection), it is possible to prevent an erroneous determination that the oxygen sensor 40 is in a deactivated state based on the signal. The following reasons are related to the fact that a signal indicating a surplus state (although lack of fuel injection) is output immediately after the start of the fuel supply cutoff is started. One of these reasons is that it takes time to move the exhaust gas from the exhaust port of the engine to the oxygen sensor. Therefore, when the combustion is in a surplus state immediately before the start of the fuel supply cutoff, the free ECU recognizes the timing of starting the execution of the fuel supply cutoff until the exhaust gas reaches the oxygen sensor output indicating a surplus state. Due to this, a signal indicating a surplus state (although lack of fuel injection) is output immediately after the execution of the fuel supply cutoff is started. Another reason is the response delay of the oxygen sensor. Yet another reason is that the fuel adhered to the intake port enters the combustion chamber during execution of the fuel supply cutoff and performs combustion there. In this case, a signal indicating a surplus state (although lack of fuel injection) is output in a similar manner immediately after the execution of the fuel supply cutoff is started. Even when the above phenomenon occurs, the erroneous determination can be prevented by starting the above determination of the deactivation state of the oxygen sensor after a predetermined period of time has elapsed since the start of the fuel supply cutoff.

Industrial applicability

According to the present invention, it is possible to provide an activity determination system for an oxygen sensor for appropriately determining the deactivation state of the oxygen sensor and at the same time for suppressing exhaust gas degradation.

1. . . locomotive

2. . . Vehicle rack

2a. . . Left frame

2b. . . Right side frame

3. . . Power unit

5. . . seat

6. . . Handle unit

7. . . Front wheel

8. . . Footrest

9. . . rear wheel

10. . . Rear buffer unit

11. . . engine

12. . . Power transmission

13. . . Crank axle box

14. . . Cylinder block

15. . . Cylinder head

16. . . Cylinder head cover

twenty one. . . Intake duct

twenty two. . . Air cleaner

twenty three. . . exhaust vent

twenty four. . . Exhaust duct

25. . . silencer

26. . . piston

27. . . Crankshaft

28. . . link

29. . . Combustion chamber

31. . . Intake path

32. . . Fuel injection valve

33. . . Ignition device

34. . . Intake valve

35. . . Vent

36. . . Exhaust path

37. . . Fuel pipeline

38. . . Fuel tank

39. . . Fuel pump

40. . . Oxygen sensor

41. . . Rotation speed sensor

42. . . Engine temperature sensor

43. . . Intake air temperature sensor

44. . . Intake pressure sensor

45. . . Throttle position sensor

46. . . Fuel sensor

51. . . Throttle valve

52. . . catalyst

60. . . Power control unit (ECU)

61. . . Calculation part

62. . . Storage section

63. . . Input section

64. . . Output section

65. . . Fuel supply cutoff determination zone

66. . . Deactivation decision area

67. . . Poor/surplus decision area

68. . . Signal processing circuit

69. . . Input line

A. . . Virtual dotted line

G. . . ground

L1. . . solid line

L2. . . dotted line

R0. . . Internal resistance

R1. . . Pull-up resistor

R2. . . Pull-down resistor

Vcc. . . power supply

1 is a side view of a locomotive in accordance with an exemplary embodiment of the present invention;

2 is a side view of a power unit and a rear wheel in accordance with an exemplary embodiment of the present invention;

3 is a front elevational view of the vehicle frame, power unit, and rear wheel as seen from the front side of the cylinder axis, in accordance with an exemplary embodiment of the present invention;

Figure 4 is a configuration diagram of the engine and the control system;

Figure 5 is a block diagram showing the configuration of a power control unit (ECU);

Figure 6 is a schematic configuration diagram of a signal processing circuit and an oxygen sensor;

Figure 7 is a diagram showing the output characteristics of a signal processing circuit;

Figure 8 is a flow chart showing the deactivation determination process;

Figure 9 is a timing chart showing output values from the signal processing circuit in the deactivation determination process;

Figure 10 is a timing diagram showing output values from a signal processing circuit in a deactivation determination process in accordance with one of the other exemplary embodiments of the present invention;

11 is a schematic configuration diagram of a signal processing circuit and an oxygen sensor according to one of other exemplary embodiments of the present invention;

Figure 12 is a timing diagram showing output values from a signal processing circuit in a deactivation determination process in accordance with one of the other exemplary embodiments of the present invention;

Figure 13 is a flow chart showing the deactivation determination process in accordance with one of the other exemplary embodiments of the present invention;

FIG. 14 is a timing chart showing output values from a signal processing circuit in a deactivation determination process according to one of other exemplary embodiments of the present invention; and

Figure 15 is a timing diagram showing the output values in the deactivation determination process in accordance with one of the other exemplary embodiments of the present invention.

(no component symbol description)

Claims (11)

An activity determination system for an oxygen sensor (40), comprising: an oxygen sensor (40) configured to be based on an internal combustion engine when the oxygen sensor (40) is in an active state (11) outputting a signal at an oxygen concentration in the exhaust gas; a signal processing circuit (68) configured to receive the signal input thereto from the oxygen sensor (40), the signal processing circuit (68) configured to output a signal based on the signal input thereto from the oxygen sensor (40) when the oxygen sensor (40) is in the active state, the signal processing circuit (68) Configuring to output a signal that converges to a predetermined lean output value (VL) when the oxygen sensor (40) is in the active state and an oxygen sensor atmosphere is maintained in the same state as the standard atmosphere, The signal processing circuit (68) is configured to output a signal that converges to a predetermined convergence value (VP) different from the lean output value (VL) when the oxygen sensor (40) is maintained in a deactivated state. a deactivation decision area (66) configured to fall at the output value (Vd(n)) from the signal processing circuit (68) Determining that the oxygen sensor (40) is in the deactivated state when the predetermined convergence range (Rna) of the convergence value (VP) is included; and a fuel supply cutoff determination zone (65) configured to determine the current Whether to perform a fuel supply cutoff in the internal combustion engine (11), wherein the deactivation determination zone (66) is configured to output the output from the signal processing circuit (68) during execution of the fuel supply cutoff ( Vd(n)) the output value from the signal processing circuit (68) when changing toward the convergence value (VP) for a predetermined period of time (Tth) or longer (or during execution of the fuel supply cutoff) The Vd(n)) determines that the oxygen sensor (40) is in the deactivated state when the convergence value (VP) is changed by a predetermined amount (Vth) or more. An activity determination system for an oxygen sensor (40) according to claim 1, wherein the signal processing circuit (68) includes a pull-up circuit (68), and the convergence value (VP) is the pull-up circuit (68) One of the values of the pull-up voltage. An activity determining system for an oxygen sensor (40) according to claim 1, wherein the signal processing circuit (68) comprises a pull-down circuit (68), and the convergence value (VP) is the pull-down circuit (68) A value of a pull-down voltage. The activity determining system for an oxygen sensor (40) according to any one of claims 1 to 3, wherein the oxygen sensor (40) is a binary sensor. The activity determining system for an oxygen sensor (40) according to any one of claims 1 to 3, wherein the oxygen sensor (40) is a line sensor. An activity determination system for an oxygen sensor (40) of claim 1, wherein the deactivation determination zone (66) is configured to be from the signal processing circuit (68) during non-execution of the fuel supply cutoff The output value (Vd(n)) determines that the oxygen sensor (40) is in the deactivated state when it falls within the deactivation range (Rna) for a predetermined period of time or longer. An activity determination system for an oxygen sensor (40) according to claim 1, wherein the oxygen sensor (40) is a heaterless type sensor. An activity determination system for an oxygen sensor (40) of claim 1, wherein the deactivation determination zone (66) is configured to be from the signal processing circuit (68) during execution of the fuel supply cutoff The output value (Vd(n)) determines that the oxygen sensor (40) is in the deactivation when it deviates from the value of the convergence value (VP) by a predetermined amount or more toward the convergence value (VP). status. An activity determination system for an oxygen sensor (40) of claim 1, wherein the deactivation determination zone (66) is configured to be from the signal processing circuit (68) during execution of the fuel supply cutoff The output value (Vd(n)) varies from a tendency to deviate from the convergence value (VP) to a value of a turning point that converges to the convergence value (VP) toward the convergence value (VP). The oxygen sensor (40) is determined to be in the deactivated state at a predetermined amount or more. An activity determination system for an oxygen sensor (40) according to claim 1, wherein the deactivation determination zone (66) is configured to pass a predetermined time period from the start of execution of the fuel supply cutoff The determination of the deactivated state of the oxygen sensor (40) begins during execution of the fuel supply cutoff. A straddle-type vehicle comprising: an activity determination system for an oxygen sensor (40) according to any one of claims 1 to 10.