WO2010058781A1 - ガスセンサの制御装置 - Google Patents
ガスセンサの制御装置 Download PDFInfo
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- WO2010058781A1 WO2010058781A1 PCT/JP2009/069533 JP2009069533W WO2010058781A1 WO 2010058781 A1 WO2010058781 A1 WO 2010058781A1 JP 2009069533 W JP2009069533 W JP 2009069533W WO 2010058781 A1 WO2010058781 A1 WO 2010058781A1
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- timing
- cover
- temperature
- condensed water
- sensor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
- F02D41/1493—Details
- F02D41/1494—Control of sensor heater
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/4067—Means for heating or controlling the temperature of the solid electrolyte
Definitions
- the present invention relates to a control device for a gas sensor, and more particularly to control of a gas sensor that is a control device for a gas sensor provided in an exhaust system of an engine, which includes a sensor element, a cover that covers the sensor element, and a heater that raises the temperature of the sensor element. Relates to the device.
- an exhaust system of an engine has been provided with a gas sensor such as an A / F sensor or an O 2 sensor. Since ceramic is generally used for the sensor element of the gas sensor, cracking of the element occurs when the sensor element is wetted at a high temperature. In this respect, in order to prevent element cracking due to moisture, a gas sensor used in an engine exhaust system is generally provided with a cover that covers the sensor element so as to allow ventilation. On the other hand, the output of a gas sensor such as an A / F sensor or an O 2 sensor provided in the exhaust system of the engine is used for air-fuel ratio control, for example. For this reason, early activation of sensor elements is strongly desired from the viewpoint of reducing exhaust emissions as part of efforts to deal with environmental problems that are becoming increasingly important in recent years. In this respect, the gas sensor may be provided with a heater for raising the temperature of the sensor element in order to activate the sensor element at an early stage.
- Patent Documents 1 and 2 propose techniques that are considered to be relevant in that predetermined heater control is performed in consideration of condensed water.
- Patent Documents 3 and 4 propose techniques that are considered relevant in terms of techniques related to the start timing of predetermined heater control.
- Patent Document 5 proposes a technique that is considered to be relevant in terms of a technique that considers the dew condensation state.
- the sensor element is exposed to water in the exhaust system of the engine, specifically as follows.
- water vapor in the exhaust is cooled in the exhaust passage and dew condensation occurs.
- the condensed water thus generated in the exhaust passage rides on the exhaust and reaches the gas sensor, enters the cover, and further reaches the sensor element. That is, the sensor element may be flooded in this way.
- water vapor condenses in the exhaust system as the temperature decreases. Such condensation also occurs in the cover of the gas sensor.
- the condensed water generated in the cover rides on the exhaust and reaches the sensor element after the engine is restarted.
- the sensor element may be wetted in this way, for example.
- the water vapor in the exhaust is cooled by the cover and is condensed outside the cover.
- the condensed water thus generated outside the cover enters the cover together with the exhaust gas and reaches the sensor element. That is, the sensor element may be flooded in this way.
- Patent Document 2 a technique for preventing element cracking due to dew condensation water generated in the exhaust passage has been proposed in, for example, Patent Document 2 described above.
- the conventional technology for preventing element cracking due to dew condensation water generated in the exhaust passage in general, when the temperature of the exhaust passage reaches the dew point, no dew condensation water is generated. Predetermined heater control such as energization permission to the heater is performed. However, there is a process of vaporizing and disappearing in the generated condensed water. In this regard, the occurrence of element cracking due to dew condensation water generated in the exhaust passage can be greatly reduced by providing a cover, but in the conventional technology, the dew condensation water before vaporization disappears reaches the sensor element.
- the present invention has been made in view of the above-described problems, and a gas sensor control device that can suitably achieve early activation of the sensor element while more reliably preventing the occurrence of element cracking of the sensor element due to condensed water.
- the purpose is to provide.
- a control device for a gas sensor according to the present invention for solving the above-mentioned problems is provided with a sensor element, a cover that covers the sensor element, and a heater that raises the temperature of the sensor element.
- the timing estimation means for estimating whether or not the cover condensation water, which is the condensation water generated inside and outside the cover, evaporates and disappears, and whether or not the estimated timing has been reached, and the timing estimation means estimated, Heater control means for energizing the heater so that the temperature of the sensor element does not cause cracking even if the temperature of the sensor element is submerged until the cover condensation water evaporates and disappears.
- the present invention is a configuration in which the timing estimation means estimates the timing at which the cover condensed water evaporates and disappears in consideration of the temperature of the cover, and determines whether or not the estimated timing has been reached. Also good.
- the timing estimation unit calculates an integrated value of the intake air amount by integrating the intake air amount until the temperature of the cover exceeds a dew point after the engine is started. After the temperature exceeds the dew point, a subtraction value of the intake air amount is calculated by subtracting the intake air amount from the integrated value of the intake air amount, and when the subtraction value of the intake air amount becomes zero, the cover By estimating that the condensed water has been vaporized and lost, it is possible to estimate the timing at which the cover condensed water is vaporized and lost, and to determine that the timing has been reached.
- the timing estimation unit further integrates the amount of condensed water generated in each part of the exhaust system before the temperature of each part upstream of the gas sensor exceeds a dew point after starting the engine. And estimating the amount of water vapor that can be included in the exhaust gas after the temperature of each part exceeds the dew point, and when the amount of water vapor is equal to or greater than the integrated value of the amount of condensed water, By estimating that the passage dew condensation water, which is the dew condensation water generated in each part, has been vaporized and disappeared, the timing at which the passage dew condensation water is vaporized and lost is determined, it is determined that the timing has been reached, and the heater control means Until the timing at which the cover dew condensation water evaporates and the passage dew condensation water evaporates disappears, which is estimated by the timing estimation means.
- the temperature of the element may be configured to energization to said heater so as element crack even when the water is at a temperature which does not occur.
- the heater control unit when the timing estimation unit determines that at least one of the cover dew condensation water and the passage dew condensation water has arrived at a timing at which the vaporization disappears, the heater control unit further controls the sensor element.
- the heater may be activated immediately and then energized to feedback control the temperature of the sensor element to a target temperature.
- the timing estimation unit recognizes a timing at which at least one of the cover condensed water and the passage condensed water is vaporized and disappeared based on a map prepared in advance, and whether or not the timing is reached.
- the structure which determines this may be sufficient.
- early activation of the sensor element can be suitably achieved while appropriately preventing the occurrence of element cracking of the sensor element due to condensed water.
- FIG. 1 is a diagram schematically showing the ECU 1 ⁇ / b> A together with the A / F sensor 10.
- FIG. 2 is a diagram schematically showing the A / F sensor 10 provided in the exhaust pipe 40.
- FIG. 3 is a diagram schematically showing the A / F sensor 10 in cross section.
- FIG. 4 is a diagram schematically showing how exhaust flows through the exhaust pipe 40 provided with the A / F sensor 10 including the cover 12.
- FIG. 5 is a graph for explaining the process of vaporizing and disappearing the cover dew condensation water.
- FIG. 6 is a diagram roughly showing the operation of the ECU 1A in a flowchart.
- FIG. 7 is a flowchart showing an expanded operation of the ECU 1A shown as a subroutine in FIG. FIG.
- FIG. 8 is a diagram showing the effect of shortening the sensor activation time and the effect of reducing exhaust emission by the ECU 1A in comparison with the case of the prior art.
- FIG. 9 is a flowchart illustrating an operation of estimating the integrated value ⁇ W1 among the operations of the ECU 1B.
- FIG. 10 is a flowchart illustrating an operation of estimating the integrated value ⁇ W2 among the operations of the ECU 1B.
- FIG. 11 is a flowchart showing an operation of estimating and determining the vaporization disappearance timing and a predetermined heater control operation among the operations of the ECU 1B.
- FIG. 12 is a diagram schematically showing map data of saturated water vapor concentration.
- FIG. 13 is a diagram visually showing the integrated values ⁇ W1 and ⁇ W2 in a graph and visually showing the energization suppression control and the main energization control in correspondence with this.
- FIG. 1 is a diagram schematically showing a control device for a gas sensor according to the present embodiment realized by an ECU (Electronic Control Unit) 1A together with an A / F sensor 10 which is a gas sensor.
- the ECU 1A includes a microcomputer (hereinafter simply referred to as a microcomputer) 2A including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown) 2A and a low-pass.
- a filter hereinafter simply referred to as LPF) 3, a sensor circuit 4, a heater control circuit 5, an A / D converter and a D / A converter (not shown), and the like are configured.
- the A / F sensor 10 includes a sensor element 11, a cover 12 that covers the sensor element 11, and a heater 13 that raises the temperature of the sensor element 11.
- the cover 12 is not limited to a single cover, and may be composed of a plurality of covers.
- the cover 12 is constituted by an inner cover 12a and an outer cover 12b.
- the cover temperature can be, for example, the temperature of the inner cover 12a.
- the temperature of the inner cover 12a is the cover temperature.
- the A / F sensor 10 is provided in an exhaust pipe 40 that distributes exhaust of an engine 50 mounted on a vehicle (not shown) (see FIG. 2).
- the A / F sensor 10 is provided in a portion of the exhaust pipe 40 on the upstream side of the catalyst 30.
- FIG. 3 is a diagram schematically showing the A / F sensor 10 in cross section.
- the A / F sensor 10 includes a first outer cylinder part 15, a second outer cylinder part 16, an upper cover 17, and the like that cover the rear end of the housing 14 and the sensor element 11. Configured.
- the cover 12 side of the A / F sensor 10 is referred to as a front end side
- the upper cover 17 side is referred to as a rear end side.
- the cover 12 is provided so as to cover the detection unit 11 a formed at the tip of the sensor element 11.
- the heater 13 (not shown in FIG. 3) is specifically provided in the sensor element 11.
- a screw portion 14 a is formed on the outer peripheral surface of the housing 14, and the A / F sensor 10 specifically engages the screw portion 14 a with the screw portion formed in the exhaust pipe 40, so that the detection portion 11 a is It is provided so as to protrude into the exhaust passage inside the exhaust pipe 40.
- FIG. 4 is a diagram schematically showing an enlarged view of the exhaust gas flowing through the exhaust pipe 40 provided with the A / F sensor 10 including the cover 12.
- the A / F sensor 10 including the cover 12 when exhaust gas including condensed water enters the outer cover 12b and then collides with the inner cover 12a, most of the condensed water in the exhaust gas is separated and the outer cover 12b Released to the outside. For this reason, in the A / F sensor 10 including the cover 12, it is possible to greatly reduce the situation in which condensed water reaches the sensor element 11.
- the energization of the heater 13 is controlled as will be described later in order to more reliably prevent such element cracking of the sensor element 11 due to dew condensation water inside and outside the cover 12.
- the sensor element 11 is inserted into the insertion hole of the insulator 18 a disposed in the housing 14, and the detection portion 11 a at the tip protrudes beyond the tip of the housing 14 fixed to the exhaust pipe 40.
- a talc powder 19 is sealed on the rear end side in the axial direction of the insulator 18a, and a packing 20 and a stator 21 are disposed on the rear end side in the axial direction of the talc powder 19.
- the sensor element 11 is fixed by caulking the rear end side outer peripheral portion of the housing 14 toward the stator 21.
- a first outer cylinder portion 15 is fixed to the rear end side of the housing 14, and a second outer cylinder portion 16 is fixed to the rear end side of the first outer cylinder portion 15.
- An insulator 18b is provided in the second outer cylinder portion 16.
- An upper cover 17 is provided on the rear end side of the second outer cylinder portion 16 via a water repellent filter 22. Atmosphere introduction holes 16a and 17a are formed at positions of the second outer cylinder portion 16 and the upper cover 17 facing the water repellent filter 22, and are formed in the second outer cylinder portion 16 through the atmosphere introduction holes 16a and 17a. Air is introduced into the atmosphere. Further, a grommet 23 is disposed inside the rear end of the upper cover 17.
- the A / F sensor 10 is provided with connectors 24a and 24b and lead wires 25a and 25b.
- the heater 13 can be energized by lead wires 25a and 25b extending to the outside of the A / F sensor 10 via connectors 24a and 24b.
- the A / F sensor 10 is similarly provided with connectors and lead wires necessary for detecting the output of the sensor element 11.
- the microcomputer 2 ⁇ / b> A when detecting the output of the A / F sensor 10, the microcomputer 2 ⁇ / b> A outputs a signal for applying a voltage to the sensor element 11. This signal is converted into a rectangular analog voltage by the D / A converter, and then the high frequency component is removed by the LPF 3 and then input to the sensor circuit 4.
- the sensor circuit 4 applies a voltage to the sensor element 11 based on the input analog voltage.
- the microcomputer 2A detects the current flowing through the sensor element 11 from the A / F sensor 10 according to the oxygen concentration in the exhaust gas as the voltage is applied via the sensor circuit 4 and the A / D converter.
- the heater control circuit 5 controls energization to the heater 13 under the control of the microcomputer 2A.
- the microcomputer 2 ⁇ / b> A controls the heater control circuit 5 so as to energize the heater 13, power is supplied from the battery 6 to the heater 13.
- the microcomputer 2A controls the heater control circuit 5 to perform duty control on energization to the heater 13.
- the microcomputer 2A detects the current and voltage of the heater 13 via the heater control circuit 5 and the A / D converter.
- the microcomputer 2A calculates impedance and admittance based on the detected value.
- the A / F sensor 10 (more specifically, the heater 13) is electrically connected to the ECU 1A as a control target.
- the ECU 1A includes an outside air temperature sensor that detects the outside air temperature of the vehicle, a crank angle sensor that is used to detect the engine speed NE, and a water temperature that detects the engine coolant temperature THW.
- Various sensors (not shown) such as sensors and an air flow meter for detecting the intake air amount of the engine are electrically connected.
- the information based on the output state and output of various sensors may be acquired indirectly via other ECUs.
- the ROM is configured to store a program describing various processes executed by the CPU, map data, and the like.
- the ECU 1A executes various processes based on a program stored in the ROM while using a temporary storage area of the RAM as necessary, so that various control means, determination means, detection means, calculation means, and the like are functional in the ECU 1A. To be realized. In this respect, in the present embodiment, the timing estimation means and the heater control means described below are functionally realized by the ECU 1A.
- the timing estimation means estimates the timing at which condensed water generated from the A / F sensor 10 upstream of the A / F sensor 10 in the exhaust system evaporates and disappears, and determines that the timing has been reached.
- the timing estimation means specifically estimates the timing as follows and determines that the timing has been reached.
- the timing estimation means considers the temperature of the cover 12, and the cover dew condensation that is the dew condensation water generated inside and outside the cover 12 among the dew condensation water generated upstream of the A / F sensor 10 from the A / F sensor 10. Estimate and determine the timing at which water evaporates and disappears.
- the timing estimation means integrates the intake air amount until the temperature of the cover 12 exceeds the dew point after the engine is started. Calculate the integrated value.
- whether or not the temperature of the cover 12 exceeds the dew point can be determined by whether or not the integrated value of the intake air amount exceeds a predetermined value A, for example.
- the predetermined value A is an integrated value of the intake air amount until the temperature of the cover 12 reaches the dew point temperature after the engine is started.
- the temperature of the cover 12 is not limited to a method obtained from the integrated value of the intake air amount, and may be estimated by calculation based on other parameters, or may be directly detected by a temperature sensor or the like.
- the timing estimation means subtracts the intake air amount from the integrated value of the intake air amount to calculate a subtracted value of the intake air amount.
- the timing estimation unit estimates and determines the timing at which the condensed water in the cover 12 is vaporized and lost by estimating that the condensed water in the cover 12 has been vaporized and lost. .
- FIG. 5 is a graph for explaining the process of vaporizing and disappearing the cover dew condensation water. Note that the time axes of the graphs shown in FIGS. 5A to 5E are the same. As shown in FIG. 5 (a), the cover temperature after the engine start, rising over time, above the dew point when passed the dew point arrival time t 0. As shown in FIG. 5 (b), condensation water increases during the period until the dew point arrival time t 0, decreases after the lapse of the dew point arrival time t 0. As shown in FIG.
- the water vapor concentration Cd at the dew point temperature Td and the saturated water vapor concentration difference ⁇ C1 which is the concentration difference between the water vapor concentrations Cex at each temperature Tex, decrease with time.
- the concentration difference ⁇ C1 is greater than zero when the engine is started, becomes zero at the dew point arrival time t 0 , and becomes smaller than zero after the dew point arrival time t 0 has elapsed.
- the magnitude of the concentration difference ⁇ C1 varies similarly to changes in condensation water before and after the dew point arrival time t 0. Therefore, the concentration difference ⁇ C1 can be assumed to be constant in relation to the amount of condensed water. As shown in FIG. 5 (d), the exhaust gas flow rate increases immediately after the engine is started, and then changes as shown.
- the integrated value of the exhaust gas flow rate is calculated until it exceeds a predetermined value. Then, after the integrated value of the exhaust gas flow rate exceeds a predetermined value, a subtracted value of the exhaust gas flow rate is calculated. And when the subtraction value of the exhaust gas flow rate becomes zero, the amount of condensed water also becomes zero.
- the integrated value of the exhaust gas flow rate is proportional to the amount of condensed water, and the subtracted value of the exhaust gas flow rate is proportional to the allowance for gasification.
- the amount of condensed water can be calculated by the following equation (1).
- Condensed water amount ⁇ (Cd-Cex) x exhaust gas flow rate ⁇ C1 x exhaust gas flow rate (1)
- the amount of condensed water can be modified as shown in the following equation (2).
- ⁇ is a constant.
- the exhaust gas flow rate can be assumed as shown in equation (3).
- Exhaust gas flow rate ⁇ Intake air amount (3) Equation (2) can be modified from Equation (3) as shown in Equation (4).
- Condensed water amount ⁇ ⁇ ⁇ intake air amount (4) the amount of condensed water is proportional to the amount of intake air. Accordingly, the disappearance timing of the cover dew condensation water can be estimated and determined by addition / subtraction of the intake air amount (that is, when the subtraction value of the exhaust gas flow rate becomes zero).
- the timing estimation means includes: In consideration of the temperature of the cover 12, for example, the timing at which condensed water evaporates and disappears is estimated in advance, and it is determined whether the timing has been reached by determining whether the timing has been estimated in advance. It may be configured. Further, the timing estimation means estimates not only the timing at which the condensed water in the cover 12 is vaporized and lost, but also the timing at which the channel condensed water that is condensed water generated in each part upstream of the A / F sensor 10 is vaporized and lost.
- the timing estimation means calculates in advance a timing at which the condensed water of the cover 12 evaporates and / or a timing at which the passage condensed water evaporates and disappears, and refers to the map after the engine is started. It may be determined whether or not the timing has been reached.
- the heater control means causes element cracking even when the element temperature is exposed to water until the timing at which the condensed water (specifically, condensed water on the cover 12) evaporates and disappears estimated by the timing estimation means.
- the heater 13 is energized so that the temperature does not reach (this energization control is hereinafter referred to as energization suppression control).
- the heater control unit performs energization suppression control until the timing estimation unit estimates and determines the timing at which the cover condensed water evaporates and disappears after the engine is started.
- the “temperature at which the element does not crack even when the element temperature is wet” refers to the type, material, size and structure of the sensor element 11 applied to the A / F sensor 10 and the installation location of the A / F sensor 10. Etc. can be determined. Further, the heater control means activates the sensor element 11 quickly when the timing estimation means determines that the timing at which the condensed water (specifically, the condensed water on the cover 12) evaporates and disappears is reached. Thereafter, the heater 13 is energized to feedback (hereinafter referred to as FB) control of the element temperature to the target temperature (hereinafter, this energization control is referred to as main energization control).
- FB feedback
- the energization suppression control is canceled when the main energization control is performed.
- Energization of the heater 13 is performed by duty control, and the energization state is switched by changing the heater DUTY related to duty control.
- the FB control is specifically performed by determining the element temperature T based on the impedance and performing duty control on the energization of the heater 13 so that the impedance becomes a predetermined impedance corresponding to the target temperature.
- the target temperature for FB control is set to a predetermined activation temperature. Note that the FB control may be performed by admittance instead of impedance.
- the process performed by the ECU 1 ⁇ / b> A includes a process of starting energization suppression control (step S ⁇ b> 11), a process of estimating the amount of generated dew condensation water (step S ⁇ b> 12), and the vaporization disappearance timing of the generated dew condensation water of the cover 12.
- the process can be roughly divided into a process for estimating and determining (step S13) and a process for performing predetermined heater control (step S14).
- FIG. 7 shows these subroutine processes in a series of flowcharts.
- steps S21 and S22 correspond to step S11
- steps S23 and S24 correspond to step S12
- steps S25 and S26 correspond to step S13
- step S27 corresponds to step S14, respectively.
- the ECU 1A determines whether or not the engine has been started (step S21). Whether or not the engine has been started can be determined, for example, based on whether or not the ignition SW is turned on. If a negative determination is made in step S21, the determination process shown in step S21 is repeated until an affirmative determination is made. On the other hand, if the determination in step S21 is affirmative, the ECU 1A starts energization suppression control (step S22). Subsequently, the ECU 1A integrates the intake air amount to calculate an integrated value of the intake air amount (step S23). Further, the ECU 1A determines whether or not the integrated value of the intake air amount has exceeded a predetermined value A (step S24). If a negative determination is made, the process returns to step S23, and the integrated value of the intake air amount is continuously calculated until an affirmative determination is made in step S24.
- step S24 determines whether or not the subtraction value of the intake air amount is zero. If a negative determination is made in step S26, the process returns to step S25, and the subtraction value of the intake air amount is continuously calculated until an affirmative determination is made in step S26.
- step S26 it is determined that the condensed water in the generated cover 12 has been vaporized and lost. For this reason, if an affirmative determination is made in step S26, the ECU 1A cancels the energization suppression control and executes the main energization control as predetermined heater control (step S27). Thereby, generation
- FIG. 8 is a diagram showing the effect of shortening the sensor activation time and the effect of improving exhaust emission by the ECU 1A in comparison with the case of the prior art.
- energization suppression control is performed before the estimated dew point arrival timing is reached, and after the estimated dew point arrival timing is reached. The case where this energization control is performed is shown.
- FIG. 8A in the case of the ECU 1A (in the case of this control), the sensor activation time can be shortened by about 10 seconds or more compared to the case of the prior art.
- the ECU 1A can start the air-fuel ratio control using the output of the A / F sensor 10 earlier, and thus it is possible to suitably achieve both prevention of element cracking and early activation of the sensor element 11.
- the ECU 1A can reduce NMHC (non-methane hydrocarbon) by about 20% as an improvement in exhaust emission as shown in FIG. it can.
- the ECU 1A estimates and determines the timing at which the condensed water in the cover 12 evaporates and disappears, thereby more reliably preventing the occurrence of element cracking of the sensor element 11 due to the condensed water and early activation of the sensor element. Can be suitably achieved, and exhaust emission can be improved.
- the ECU 1B according to the present embodiment is substantially the same as the ECU 1A except that the timing estimation unit is further configured as described below and the heater control unit is configured as described below. It has become.
- the ECU 1B is connected to a control object, various sensors, and the like, as in the first embodiment. For this reason, in this embodiment, the illustration of the ECU 1B is omitted.
- the timing estimation unit and the heater control unit according to the present embodiment can be realized by changing a program stored in the ROM of the ECU 1A.
- the timing estimation unit further evaporates and loses the passage dew condensation water that is the dew condensation water generated in each part upstream of the A / F sensor 10. It is configured to estimate the timing and determine that the timing has been reached.
- the timing estimation means first starts the engine and before the temperature Tex of each part upstream of the A / F sensor 10 exceeds the dew point.
- the integrated value ⁇ W1 of the amount of condensed water generated in each part is estimated.
- the amount of water vapor that can be contained in the exhaust gas is estimated.
- This amount of water vapor can be estimated as the magnitude (absolute value) of an integrated value ⁇ W2 of a gasification margin that will be described later.
- the timing estimation means estimates that the generated passage condensation water has vaporized and disappeared when the magnitude of the integrated value ⁇ W2 of the margin for gasification becomes equal to or greater than the integrated value ⁇ W1 of the amount of condensed water. Estimate and determine the timing of vaporization disappearance.
- the temperature Tex may be directly detected by a temperature sensor or the like, the outside air temperature and the cooling water temperature at the time of starting the engine, the exhaust gas temperature, the heat transfer coefficient between the exhaust gas and each part, and between each part and the outside air, You may make it estimate by calculation based on the specific heat, mass, etc. of each part.
- the heater control unit when the energization suppression control is performed, until the timing when the condensed water is vaporized and disappeared, which is estimated by the timing estimating unit, specifically, the condensed water of the cover 12 is vaporized.
- the timing estimation means estimates and eliminates energization suppression control until the timing at which the passage condensation water evaporates and disappears.
- the heater control means when performing the energization control, when the timing when the dew condensation water evaporates and disappears determined by the timing estimation means, specifically, the dew condensation water of the cover 12 evaporates and disappears.
- the timing estimation means estimates and determines the timing to evaporate and the timing at which passage dew condensation water evaporates and disappears.
- the main energization control is performed. This is intended to perform the heater control after estimating that all the condensed water that may cause element cracking due to moisture has been evaporated.
- FIG. 9 is a flowchart showing the integrated value ⁇ W1 estimating process
- FIG. 10 is a flowchart showing the integrated value ⁇ W2 estimating process
- FIG. 11 is a flowchart showing the evaporation timing estimating process and the heater control process.
- the flowchart shown in FIG. 9 is started after the engine is started.
- the flowchart shown in FIG. 10 is started when the cover temperature subsequently exceeds the dew point.
- the flowchart shown in FIG. 11 is started when the integrated value ⁇ W2 is first estimated in the flowchart shown in FIG.
- the ECU 1B detects the temperature Tex of each part of the exhaust system (step S31). Subsequently, the ECU 1B calculates the water vapor concentration Cex at the detected temperature Tex and the water vapor concentration Cd at the dew point temperature Td (step S32). Specifically, the ECU 1B calculates water vapor concentrations Cex and Cd corresponding to the temperatures Tex and Td with reference to the map data shown in FIG. In this step, the ECU 1B calculates a saturated water vapor concentration difference ⁇ C1 by subtracting Cex from the water vapor concentration Cd. Note that the map data of the saturated water vapor concentration shown in FIG. 12 is stored in advance in the ROM.
- the ECU 1B calculates a dew condensation water amount W1 (step S33). Specifically, the condensed water amount W1 is obtained by multiplying the exhaust gas flow rate by the concentration difference ⁇ C1. Subsequently, the ECU 1B calculates an integrated value ⁇ W1 of the amount of condensed water (step S34). Specifically, the integrated value ⁇ W1 is calculated by integrating the calculated condensed water amount W1 every time the condensed water amount W1 is calculated in step S33. Then, the ECU 1B determines whether or not the temperature Tex is higher than the dew point temperature Td (step S35). If a negative determination is made, the flowchart is temporarily ended and then restarted. Thus, the integrated value ⁇ W1 is continuously calculated until an affirmative determination is made in step S35. On the other hand, if the determination in step S35 is affirmative, the ECU 1B ends the calculation of the integrated value ⁇ W1 (step S36).
- the ECU 1B estimates an integrated value ⁇ W2 for the gasification margin. Specifically, as shown in FIG. 10, the ECU 1B first detects the temperature Tex of each part of the exhaust system (step S41). Subsequently, the ECU 1B calculates a water vapor concentration Cex at the temperature Tex and a water vapor concentration Cd at the dew point temperature Td (step S42). The calculation of the water vapor concentrations Cex and Cd is performed in the same manner as in step S32 described above. In this step, the ECU 1B calculates a saturated water vapor concentration difference ⁇ C2 by subtracting Cex from the water vapor concentration Cd. This concentration difference ⁇ C2 indicates the concentration of water vapor that can be included at the temperature Tex.
- the ECU 1B calculates a gasification margin W2 (step S43).
- the gasification margin W2 is obtained by multiplying the exhaust gas flow rate by the concentration difference ⁇ C2.
- the ECU 1B calculates the integrated value ⁇ W2 of the gasification allowance (step S44).
- the integrated value ⁇ W2 is calculated by integrating the calculated gasification margin W2 every time the gasification margin W2 is calculated in step S44.
- the ECU 1B determines whether or not the integrated value ⁇ W2 of the gasification margin is equal to or greater than the integrated value ⁇ W1 of the amount of condensed water (step S45).
- step S45 it is determined whether or not the amount of water vapor that can be included in the exhaust gas is equal to or greater than the integrated value ⁇ W1 of the amount of condensed water. If a negative determination is made in step S45, the flowchart is temporarily ended and then restarted. Thus, the integrated value ⁇ W2 is continuously calculated until an affirmative determination is made in step S45. On the other hand, if the determination in step S45 is affirmative, the ECU 1B ends the calculation of the integrated value ⁇ W2 (step S46).
- step S44 the ECU 1B determines whether or not the integrated value ⁇ W2 of the margin for gasification is equal to or greater than the integrated value ⁇ W1 of the condensed water amount as shown in FIG. S51). If the determination is negative, this flowchart is temporarily terminated. In this case, this flowchart is restarted when the integrated value ⁇ W2 is newly calculated in step S44 of the flowchart shown in FIG. On the other hand, if the determination in step S51 is affirmative, the ECU 1B estimates and determines that the generated passage dew condensation water has disappeared (step S52).
- the ECU 1B estimates and determines whether or not the cover condensed water has been vaporized and disappeared as described above in the first embodiment, including determining whether or not the cover condensed water has been vaporized and lost. (Step S53). If the determination is negative, this flowchart is temporarily terminated. In this case, this flowchart is restarted when the determination process in step S26 of the flowchart shown in FIG. 7 is newly performed. On the other hand, if the determination in step S53 is affirmative, the ECU 1B cancels the energization suppression control and executes the main energization control as predetermined heater control (step S54). Thereby, even if it is a case where the cover 12 is provided, the element cracking by the sensor element 11 getting wet with the passage dew condensation water may occur. Can be prevented.
- FIG. 13 is a diagram visually showing the integrated values ⁇ W1 and ⁇ W2 in a graph and visually showing the energization suppression control and the main energization control in correspondence with them.
- two curves indicate the concentration difference ⁇ C1 and the temperature Tex, respectively.
- the integrated value ⁇ W1 of the amount of condensed water is represented by an area surrounded by a curve of the concentration difference ⁇ C1 before the temperature Tex reaches the dew point and a straight line indicating that the concentration difference ⁇ C1 is zero.
- the integrated value ⁇ W2 of the margin for gasification is represented by the area between the curve of the concentration difference ⁇ C1 after the temperature Tex reaches the dew point and a straight line indicating that the concentration difference ⁇ C1 is zero.
- the area is further divided by a straight line indicating the time point when ⁇ W1 ⁇ ⁇ W2.
- the heater DUTY is set to a little less than 10% before the time when ⁇ W1 ⁇ ⁇ W2 is reached, so that the element temperature does not occur even if the element temperature is submerged. Yes. That is, after the engine is started, energization suppression control is performed until ⁇ W1 ⁇ ⁇ W2, and as a result, the element temperature is suppressed to a temperature at which element cracking does not occur. On the other hand, when ⁇ W1 ⁇ ⁇ W2, the energization control is performed. As a result, the heater DUTY is set to approximately 85% in order to quickly activate the sensor element 11.
- ECU 1B has a cover 12 and even if sensor element 11 is exposed to passage dew condensation water, element cracks can occur.
- the sensor element 11 can be activated at an early stage while preventing the occurrence of cracks in the wet element of the sensor element 11 due to the above.
- the timing estimation unit is configured to estimate and determine the timing at which the cover dew condensation water evaporates and disappears and the timing at which the passage dew condensation water evaporates and disappears. It is possible to estimate and determine the timing at which passage condensed water evaporates and disappears without estimating and determining the timing at which water evaporates and disappears. That is, it is considered that the timing at which passage condensation water vaporizes and disappears is usually later than the timing at which cover condensation water vaporizes and disappears. For example, when such circumstances are obvious, the timing at which cover condensation water vaporizes and disappears. It is also possible to estimate and determine the timing at which passage dew condensation water evaporates and disappears without estimating and determining.
- the timing at which the cover dew condensation water evaporates and / or the timing at which the passage dew condensation evaporates can be calculated in advance and recorded on the map according to the concepts of the first and second embodiments. Then, in a vehicle, the map may be referred to and it may be determined whether or not the timing has been reached after the engine is started.
- the timing estimation unit can recognize the timing at which the condensed water evaporates and disappears based on a map prepared in advance, and can determine whether or not the timing has been reached. In this case, the timing may be set longer as the estimated temperature of the sensor at the start of the engine becomes lower. Alternatively, the timing when the estimated temperature of the sensor at the start of the engine is low may be set longer or equivalent to the timing when the estimated temperature of the sensor at the time of starting the engine is high. .
- the timing estimation unit and the heater control unit are rationally realized by the ECU 1, but may be realized by other electronic control devices, hardware such as a dedicated electronic circuit, or a combination thereof.
- the gas sensor control device of the present invention may be realized by, for example, a plurality of electronic control devices or a combination of electronic control devices and hardware such as electronic circuits. That is, the control device for the gas sensor of the present invention may be realized in a distributed control manner, for example.
- individual means such as timing estimation means and heater control means may be realized in a distributed control manner.
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Abstract
Description
一方、エンジンの排気系に設けられたA/FセンサやO2センサなどのガスセンサの出力は例えば空燃比制御に用いられる。このため、近年重要性が高まっている環境問題への取り組みの一環として、排気エミッションを低減する観点からセンサ素子の早期活性化は強く望まれている。この点、センサ素子の早期活性化を図るため、ガスセンサはセンサ素子を昇温するヒータを備えていることがある。
例えばエンジン始動後には、排気が排気通路に接触した際に排気中の水蒸気が排気通路で冷却されて結露する。こうして排気通路で発生した結露水は排気に乗ってガスセンサに到達するとともにカバー内に侵入し、さらにセンサ素子に到達する。すなわちセンサ素子はこのようにして被水することがある。
一方、例えばエンジンが停止した場合、排気系では温度の低下に応じて水蒸気が結露する。また、このような結露はガスセンサのカバー内でも発生する。そしてカバー内で発生した結露水はエンジンの再始動後に、排気に乗ってセンサ素子に到達する。すなわちセンサ素子は例えばこのようにして被水することもある。
また、例えばエンジン始動後には、排気がカバーに接触した際に排気中の水蒸気がカバーで冷却されてカバー外に結露する。こうしてカバー外で発生した結露水は排気とともにカバー内に侵入し、センサ素子に到達する。すなわちセンサ素子はこのようにして被水することもある。
しかしながら、発生した結露水には気化消失する過程が存在する。この点、排気通路で発生した結露水による素子割れの発生はカバーを備えることで大幅に低減し得るものの、当該従来技術では気化消失する前の結露水がセンサ素子に到達し、この結果、素子割れが発生する虞がないとはいえない点で問題があった。
また、仮に排気通路で発生した結露水による素子割れをカバーで防止できるとした場合でも、結露水は上述の通りカバーの内外でも発生する。このため、カバーの温度を特段考慮していない従来技術では、カバーの内外で発生した結露水により素子割れが発生する虞がある点で問題があった。
本実施例では、このようなカバー12の内外への結露水によるセンサ素子11の素子割れをより確実に防止するために、後述するようにヒータ13の通電を制御する。
ROMはCPUが実行する種々の処理が記述されたプログラムやマップデータなどを格納するための構成である。CPUがROMに格納されたプログラムに基づき、必要に応じてRAMの一時記憶領域を利用しつつ処理を実行することで、ECU1Aでは各種の制御手段や判定手段や検出手段や算出手段などが機能的に実現される。この点、本実施例では特に以下に示すタイミング推定手段とヒータ制御手段とがECU1Aで機能的に実現されている。
タイミング推定手段は、カバー12の温度を考慮して、A/Fセンサ10からA/Fセンサ10よりも上流側で発生した結露水のうち、カバー12の内外で発生する結露水であるカバー結露水が気化消失するタイミングを推定するとともに判定する。具体的には、インナーカバー12aの温度を考慮して、インナーカバー12aとアウターカバー12bのセンサ素子11側(カバー内)、および排気通路側(カバー外)に発生する結露水が気化消失するタイミングを推定するとともに判定する。
また、カバー12の温度が露点を超えた後、タイミング推定手段は吸入空気量の積算値から吸入空気量を減算して吸入空気量の減算値を算出する。
そして吸入空気量の減算値がゼロになった場合に、タイミング推定手段はカバー12の結露水が気化消失したと推定することで、カバー12の結露水が気化消失するタイミングを推定するとともに判定する。
図5はカバー結露水が気化消失する過程をグラフで説明する図である。なお、図5(a)から図5(e)までに示す各グラフの時間軸は同じになっている。
図5(a)に示すように、カバー温度はエンジン始動後、時間経過とともに上昇し、露点到達時刻t0を経過したときに露点を超える。
図5(b)に示すように、結露水量は露点到達時刻t0を経過するまでの間増大し、露点到達時刻t0を経過した後減少する。
図5(c)に示すように、露点温度Tdにおける水蒸気濃度Cdと、各温度Texにおける水蒸気濃度Cexの濃度差である飽和水蒸気濃度差ΔC1は時間経過とともに減少する。濃度差ΔC1はエンジン始動時にはゼロよりも大きく、露点到達時刻t0でゼロとなり、露点到達時刻t0を経過した後ではゼロよりも小さくなる。また濃度差ΔC1の大きさは露点到達時刻t0の前後で結露水量の変化に対して同様に変化する。このため濃度差ΔC1は結露水量との関係では一定と仮定しても差し支えない。
図5(d)に示すように、排気ガス流量はエンジン始動直後に増大し、その後図示のように変化する。
図5(e)に示すように、排気ガス流量の積算値は所定値を超えるまで算出される。そして排気ガス流量の積算値が所定値を超えた後には排気ガス流量の減算値が算出される。そして排気ガス流量の減算値がゼロになったときに結露水量もゼロとなる。排気ガス流量の積算値は結露水量に比例し、排気ガス流量の減算値はガス化余裕代に比例する。
結露水量≒(Cd-Cex)×排気ガス流量=ΔC1×排気ガス流量・・・(1)
この点、濃度差ΔC1を一定と仮定すれば、結露水量は次の式(2)に示すように変形することができる。
結露水量≒α×排気ガス流量・・・(2)
ここでαは定数である。
さらに排気ガス流量は式(3)に示すように仮定することができる。
排気ガス流量≒吸入空気量・・・(3)
式(2)は、式(3)より式(4)に示すように変形することができる。
結露水量≒α×吸入空気量・・・(4)
この式(4)によれば、結露水量は吸入空気量に比例することとなる。したがって、カバー結露水の消失タイミングは吸入空気量の加減算によって(すなわち排気ガス流量の減算値がゼロになったことによって)推定するとともに判定することができる。
また、タイミング推定手段は、カバー12の結露水が気化消失するタイミングだけでなく、A/Fセンサ10よりも上流側の各部で発生する結露水である通路結露水が気化消失するタイミングも推定し、これらの推定結果から当該タイミングに到達したことを判定するように構成されてもよい(実施例2参照)。更に、タイミング推定手段は、カバー12の結露水が気化消失するタイミングおよび/または通路結露水が気化消失するタイミングを予め計算してマップに記録しておき、エンジン始動後に当該マップを参照して、当該タイミングに達したか否かを判断してもよい。
また、ヒータ制御手段は、タイミング推定手段が結露水(ここでは具体的にはカバー12の結露水)が気化消失するタイミングに到達したことを判定したときに、センサ素子11を速やかに活性化させ、その後、素子温を目標温度にフィードバック(以下、FBと称す)制御する通電をヒータ13に対して行う(以下、この通電制御を本通電制御と称す)。この点、通電抑制制御は本通電制御を行うときに解除されることになる。
ヒータ13への通電はデューティ制御で行われ、通電状態はデューティ制御に係るヒータDUTYを変更することで切り換えられる。また、FB制御は具体的には素子温Tをインピーダンスで判定するとともに、インピーダンスが目標温度に対応する所定のインピーダンスになるようにヒータ13への通電をデューティ制御することで行われる。また、FB制御に係る目標温度は所定の活性温度に設定されている。なお、FB制御はインピーダンスの代わりにアドミタンスで行われてもよい。
このように、ECU1Aはカバー12の結露水が気化消失するタイミングを推定するとともに判定することで、結露水よるセンサ素子11の素子割れの発生をより確実に防止しつつ、センサ素子の早期活性化を好適に図ることができ、さらには排気エミッションの改善を図ることもできる。
通路結露水が気化消失するタイミングを推定するとともに判定するにあたり、タイミング推定手段は具体的には、まずエンジンの始動後、A/Fセンサ10よりも上流側の各部の温度Texが露点を超える前に、各部で発生する結露水量の積算値ΣW1を推定する。次に温度Texが露点を超えた後に、排気ガス中に含むことが可能な水蒸気量を推定する。この水蒸気量は後述するガス化余裕代の積算値ΣW2の大きさ(絶対値)として推定することができる。そしてタイミング推定手段は、ガス化余裕代の積算値ΣW2の大きさが、結露水量の積算値ΣW1以上になった場合に、発生した通路結露水が気化消失したと推定することで、通路結露水が気化消失するタイミングを推定するとともに判定する。
なお、温度Texは温度センサ等で直接検知するようにしてもよく、エンジン始動時の外気温および冷却水温や、排気ガス温度や、排気ガス-各部間および各部-外気間の熱伝達率や、各部の比熱および質量などをもとに演算で推定するようにしてもよい。
また、本実施例に係るヒータ制御手段は、本通電制御を行うにあたり、タイミング推定手段が判定した、結露水が気化消失するタイミングを迎えたとき、具体的にはカバー12の結露水が気化消失するタイミングおよび通路結露水が気化消失するタイミングをタイミング推定手段が推定するとともに判定したときに、本通電制御を行うように構成されている。
これは、被水による素子割れを引き起こすおそれがある結露水の全てが気化消滅したことを推定した上でヒータ制御を行う趣旨である。
このように、ECU1BはECU1Aと比較して、カバー12を備えた場合であってもセンサ素子11が通路結露水を被水することによる素子割れが発生し得ることに対して、さらに通路結露水によるセンサ素子11の被水素子割れの発生をより確実に防止しつつ、センサ素子の早期活性化を好適に図ることができる。
例えば実施例2では、カバー結露水が気化消失するタイミングおよび通路結露水が気化消失するタイミングを推定するとともに判定するようにタイミング推定手段を構成した場合について示したが、タイミング推定手段は、カバー結露水が気化消失するタイミングを推定するとともに判定することなく、通路結露水が気化消失するタイミングを推定するとともに判定するように構成することも可能である。すなわち、通路結露水が気化消失するタイミングのほうが、カバー結露水が気化消失するタイミングよりも通常遅くなると考えられるところ、例えばこのような事情が明らかな場合には、カバー結露水が気化消失するタイミングを推定するとともに判定することなく、通路結露水が気化消失するタイミングを推定するとともに判定するようにすることも可能である。
10 A/Fセンサ
11 センサ素子
12 カバー
13 ヒータ
30 触媒
40 排気管
50 エンジン
Claims (6)
- センサ素子と、該センサ素子を覆うカバーと、前記センサ素子を昇温するヒータとを備え、エンジンの排気系に設けられたガスセンサにつき、
前記カバーの内外で発生した結露水であるカバー結露水が気化消失するタイミングを推定するとともに、推定したタイミングに到達したか否かを判定するタイミング推定手段と、
前記タイミング推定手段が推定した、前記カバー結露水が気化消失するタイミングを迎えるまでの間、前記センサ素子の温度が被水しても素子割れが発生しない温度になるように前記ヒータに通電をするヒータ制御手段とを備えるガスセンサの制御装置。 - 前記タイミング推定手段は、前記カバーの温度を考慮して、前記カバー結露水が気化消失するタイミングを推定するとともに、推定したタイミングに到達したか否かを判定することを特徴とする請求項1記載のガスセンサの制御装置。
- 前記タイミング推定手段は、前記エンジンの始動後、前記カバーの温度が露点を超えるまでの間、吸入空気量を積算して吸入空気量の積算値を算出するとともに、前記カバーの温度が露点を超えた後に、前記吸入空気量の積算値から吸入空気量を減算して吸入空気量の減算値を算出し、
前記吸入空気量の減算値がゼロになった場合に、前記カバー結露水が気化消失したと推定することで、前記カバー結露水が気化消失するタイミングを推定するとともに、当該タイミングに到達したことを判定することを特徴とする請求項1または2記載のガスセンサの制御装置。 - 前記タイミング推定手段は、さらに前記エンジンの始動後、前記排気系のうち、前記ガスセンサよりも上流側の各部の温度が露点を超える前に、前記各部で発生する結露水量の積算値を推定するとともに、前記各部の温度が露点を超えた後に、排気ガス中に含むことが可能な水蒸気量を推定し、
前記水蒸気量が前記結露水量の積算値以上になった場合に、前記各部で発生した結露水である通路結露水が気化消失したと推定することで、前記通路結露水が気化消失するタイミングを推定するとともに、当該タイミングに到達したことを判定し、
前記ヒータ制御手段は、前記タイミング推定手段が推定した、前記カバー結露水が気化消失するタイミング及び前記通路結露水が気化消失するタイミングを迎えるまでの間、前記センサ素子の温度が被水しても素子割れが発生しない温度になるように前記ヒータに通電をすることを特徴とする請求項1から3のいずれか1項記載のガスセンサの制御装置。 - 前記タイミング推定手段は、前記カバー結露水と、前記通路結露水との少なくとも一方が気化消失するタイミングに到達したことを判定したときに、前記ヒータ制御手段がさらに前記センサ素子を速やかに活性化させ、その後、前記センサ素子の温度を目標温度にフィードバック制御する通電を前記ヒータに対して行うことを特徴とする請求項1から4のいずれか1項記載のガスセンサの制御装置。
- 前記タイミング推定手段は、予め用意されたマップに基づいて前記カバー結露水と、前記通路結露水との少なくとも一方が気化消失するタイミングを認識し、該タイミングに到達したか否かを判定することを特徴とする請求項1から5のいずれか1項記載のガスセンサの制御装置。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP09827562.1A EP2352019B1 (en) | 2008-11-19 | 2009-11-18 | Gas sensor control device |
JP2010539235A JP5152339B2 (ja) | 2008-11-19 | 2009-11-18 | ガスセンサの制御装置 |
US13/128,956 US8731861B2 (en) | 2008-11-19 | 2009-11-18 | Gas sensor control device |
CN2009801460118A CN102216763B (zh) | 2008-11-19 | 2009-11-18 | 气体传感器的控制装置 |
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US (1) | US8731861B2 (ja) |
EP (1) | EP2352019B1 (ja) |
JP (1) | JP5152339B2 (ja) |
CN (1) | CN102216763B (ja) |
WO (1) | WO2010058781A1 (ja) |
Cited By (1)
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CN102565152A (zh) * | 2010-12-17 | 2012-07-11 | 株式会社电装 | 气体传感器 |
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US9784708B2 (en) | 2010-11-24 | 2017-10-10 | Spec Sensors, Llc | Printed gas sensor |
US9163551B2 (en) * | 2011-02-07 | 2015-10-20 | Toyota Jidosha Kabushiki Kaisha | Cooling system for internal combustion engine |
EP3191834B1 (en) | 2014-09-12 | 2024-09-04 | Sensirion AG | Breath sampling devices and methods of breath sampling using sensors |
JP6372789B2 (ja) | 2015-04-17 | 2018-08-15 | 株式会社デンソー | フィルタの故障診断装置 |
US10241073B2 (en) | 2015-05-26 | 2019-03-26 | Spec Sensors Llc | Wireless near-field gas sensor system and methods of manufacturing the same |
JP6493281B2 (ja) * | 2016-04-11 | 2019-04-03 | トヨタ自動車株式会社 | 排気センサの制御装置 |
JP6451697B2 (ja) * | 2016-06-14 | 2019-01-16 | トヨタ自動車株式会社 | 排気センサの制御装置 |
JP6658573B2 (ja) * | 2017-01-26 | 2020-03-04 | トヨタ自動車株式会社 | 内燃機関の制御装置 |
CN112135961B (zh) | 2017-10-10 | 2021-11-30 | 康明斯公司 | 减轻由于水冷凝而导致的传感器故障的系统和方法 |
JP7003879B2 (ja) * | 2018-09-03 | 2022-01-21 | トヨタ自動車株式会社 | 粉体搬送システム |
JP7239434B2 (ja) * | 2019-10-03 | 2023-03-14 | 日本碍子株式会社 | ガスセンサ及び保護カバー |
DE102020214450A1 (de) | 2020-11-17 | 2022-05-19 | Fronius International Gmbh | Verfahren und Vorrichtung zur Vermeidung von Kondenswasserbildung bei einem Inverter |
CN113008944B (zh) * | 2020-12-04 | 2022-04-05 | 西安交通大学 | 一种基于虚拟交流阻抗的半导体气体传感器测量方法 |
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- 2009-11-18 US US13/128,956 patent/US8731861B2/en not_active Expired - Fee Related
- 2009-11-18 CN CN2009801460118A patent/CN102216763B/zh not_active Expired - Fee Related
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Also Published As
Publication number | Publication date |
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EP2352019A4 (en) | 2013-12-25 |
EP2352019A1 (en) | 2011-08-03 |
JP5152339B2 (ja) | 2013-02-27 |
JPWO2010058781A1 (ja) | 2012-04-19 |
CN102216763A (zh) | 2011-10-12 |
US8731861B2 (en) | 2014-05-20 |
EP2352019B1 (en) | 2015-01-14 |
CN102216763B (zh) | 2013-12-18 |
US20110246090A1 (en) | 2011-10-06 |
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