JP2013068205A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent temperature difference within a catalyst from expanding by using an electric heating catalyst when exhaust gas passes through the catalyst.SOLUTION: An ECU carries out a program including: a step (S100) for acquiring the amount of a pedal stroke; a step (S102) for calculating a requested power Pe; a step (S104) for acquiring a catalyst temperature Tc; a step (S106) for estimating temperature differenceΔTc; a step (S110) for determining an electric power distribution pattern when the temperature difference ΔTc is greater than a threshold ΔTc (0) (YES in S108); and a step (S112) for performing an electric power distribution control.

Description

  The present invention relates to energization control of an electric heating catalyst provided in an exhaust pipe of an engine.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2010-223159 (Patent Document 1), an electrically heated catalyst that raises the catalyst temperature by energizing the catalyst using an electrode is known.

JP 2010-223159 A

  By the way, when the exhaust gas passes through the catalyst, the temperature distribution is such that the center side of the catalyst is in a high temperature state and the outer peripheral side of the catalyst is in a low temperature state. Since such a temperature difference increases as the temperature change increases, there is a problem that thermal stress due to the temperature difference is generated in the catalyst.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress an increase in temperature difference inside the catalyst using an electrically heated catalyst when exhaust gas passes through the catalyst. Is to provide a vehicle.

  A vehicle according to an aspect of the present invention includes an engine, a catalyst that is provided in an exhaust pipe of the engine and is formed of a uniform material, and an electrode that is attached to the outer periphery of the catalyst and heats the catalyst. An exhaust emission control device and a control device for executing energization control for passing current to the electrode when exhaust gas from the engine passes through the catalyst are included.

  Preferably, the control device determines whether to execute energization control based on the operating state of the engine and the temperature of the catalyst.

  More preferably, the control device performs energization control when the catalyst state based on the engine operating state and the catalyst temperature is in a state where the difference in temperature in the temperature distribution within the catalyst is greater than a threshold value. Run.

  More preferably, the control device does not execute the energization control when the state of the catalyst is in a state where the height difference is smaller than a threshold value.

  More preferably, the control device determines the energization power and the energization time based on the engine operating state and the catalyst temperature when the energization control is executed.

More preferably, the uniform material is a single material.
More preferably, the catalyst has a cylindrical shape. The electrode is provided on the outer peripheral surface of the catalyst, and has a connection portion connected to a power source, and a first electrode having a cross-sectional portion having a bow-shaped cross section partially covering the outer peripheral surface of the catalyst around the connection portion. And a second electrode having the same shape as the first electrode and provided at a position facing each other with a catalyst interposed therebetween. The cross-sectional portion is formed so as to become thinner as the position is farther from the connection portion.

1 is an overall block diagram of a vehicle according to an embodiment. It is a figure which shows the cross section of EHC. It is a figure which shows the temperature distribution from a catalyst center part to an electrode. It is a functional block diagram of ECU mounted in the vehicle which concerns on this Embodiment. It is a timing chart for demonstrating the change of the temperature difference inside a catalyst according to the request | requirement power with respect to an engine. It is a flowchart which shows the control structure of the program performed with ECU mounted in the vehicle which concerns on this Embodiment. It is a figure which shows the temperature distribution inside a catalyst at the time of the electricity supply from an electrode to a catalyst. It is a figure which shows the temperature distribution from a catalyst center part to an electrode at the time of supplying with electricity to a catalyst from the electrode during passage of exhaust gas.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  Referring to FIG. 1, an overall block diagram of hybrid vehicle 1 (simply referred to as vehicle 1 in the following description) according to the present embodiment will be described. The vehicle 1 includes an engine 10, a drive shaft 16, a first motor generator (hereinafter referred to as a first MG) 20, a second motor generator (hereinafter referred to as a second MG) 30, and a power split device 40. , A reduction gear 58, a PCU (Power Control Unit) 60, a battery 70, a charging device 78, a drive wheel 80, and an ECU (Electronic Control Unit) 200.

  The vehicle 1 travels with driving force output from at least one of the engine 10 and the second MG 30. The power generated by the engine 10 is divided into two paths by the power split device 40. One of the two routes is a route transmitted to the drive wheel 80 via the speed reducer 58, and the other route is a route transmitted to the first MG 20.

  First MG 20 and second MG 30 are, for example, three-phase AC rotating electric machines. First MG 20 and second MG 30 are driven by PCU 60.

  The first MG 20 has a function as a generator that generates power using the power of the engine 10 divided by the power split device 40 and charges the battery 70 via the PCU 60. Further, first MG 20 receives electric power from battery 70 and rotates crankshaft 18 that is the output shaft of engine 10. Thus, the first MG 20 has a function as a starter for starting the engine 10.

  Second MG 30 has a function as a driving motor that applies driving force to driving wheels 80 using at least one of the electric power stored in battery 70 and the electric power generated by first MG 20. Second MG 30 also has a function as a generator for charging battery 70 via PCU 60 using electric power generated by regenerative braking.

  The engine 10 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine.

  The engine 10 includes a plurality of cylinders 102, a fuel injection device 104 that supplies fuel to each of the plurality of cylinders 102, an exhaust manifold 106, an exhaust passage 108, an EHC (electrically heated catalyst) 110, and a catalyst temperature sensor. 114. It should be noted that one or more cylinders 102 of the engine 10 may be provided.

  Based on the control signal S1 from the ECU 200, the fuel injection device 104 injects an appropriate amount of fuel to each cylinder at an appropriate time, or stops fuel injection to each cylinder. The fuel injection amount by the fuel injection device 104 is adjusted by the injection time.

  One end of the exhaust passage 108 is connected to the exhaust manifold 106. The other end of the exhaust passage 108 is connected to a muffler (not shown). An EHC 110 is provided in the middle of the exhaust passage 108.

  EHC 110 includes a catalyst for purifying exhaust gas, and a positive electrode 116 and a negative electrode 118 for energizing the catalyst. The EHC 110 is not particularly limited as long as the temperature of the catalyst is raised by energizing the catalyst using an electrode, and various known configurations may be used.

  FIG. 2 shows a cross section of the catalyst 154 in the EHC 110. As shown in FIG. 2, the catalyst 154 in the EHC 110 has a cylindrical shape. The base material portion of the catalyst 154 is formed of a uniform material. The base material portion of the catalyst 154 has a honeycomb structure using a single material member. The structure of the catalyst 154 shown in FIG. 2 is an example, and is not particularly limited to the structure shown in FIG.

  The positive electrode 116 is provided on the outer peripheral surface of the catalyst 154 and has a connection portion 150 connected to a power source, and a cross-sectional portion 152 having an arcuate cross section that partially covers the outer peripheral surface of the catalyst around the connection portion 150. And have. The cross-sectional portion 152 is formed so as to have a thinner shape as the position is farther from the connection portion 150. This is because the electrical resistance increases as the distance from the connection portion 150 increases.

  The negative side electrode 118 has the same shape as the positive side electrode 116. The negative electrode 118 is provided at a position facing the positive electrode 116 with the catalyst 154 interposed.

  PCU 60 and EHC 110 are connected by a positive electrode line and a negative electrode line. The EHC 110 is supplied with power from the battery 70 and power generated by the first MG 20 via the PCU 60. The connection relationship between the battery 70 and the EHC 110 is not limited to that shown in FIG.

  A power supply circuit 112 having a built-in relay is provided between the PCU 60 and the EHC 110, and an electrical connection state between the EHC 110 and the PCU 60 is switched based on a control signal S3 from the ECU 200. When the relay built in the power supply circuit 112 is closed, the EHC 110 and the PCU 60 are connected, and a voltage is applied to the positive electrode 116 and the negative electrode 118 in the EHC 110. When the positive electrode 116 and the negative electrode 118 are energized, Joule heat is generated in the catalyst 154 in the EHC 110, whereby the catalyst 154 in the EHC 110 is heated. When the relay built in the power supply circuit 112 is opened, the connection between the EHC 110 and the PCU 60 is cut off, and the energization to the positive electrode 116 and the negative electrode 118 is stopped. Thus, the ECU 200 controls the power supply circuit 112 to control the amount of power supplied to the catalyst 154 in the EHC 110. The ECU 200 may change the power (voltage or current) supplied to the EHC 110 by controlling the PCU 60, or may perform duty control on a relay built in the power supply circuit 112. Accordingly, the power supplied to the EHC 110 may be changed. Furthermore, a circuit that changes the power supplied to the EHC 110 may be provided in the power supply circuit 112.

  When the positive electrode 116 and the negative electrode 118 are energized, the catalyst 154 in the EHC 110 is energized. The positive side electrode 116 and the negative side electrode 118 have a bow-shaped cross section, and are formed so as to be thinner as they are away from the connection portion 150, thereby increasing electrical resistance. Therefore, a current flows uniformly through the catalyst 154 in the EHC 110 from the positive electrode 116 to the negative electrode 118.

  Returning to FIG. 1, the catalyst temperature sensor 114 detects the temperature Tc of the catalyst 154 in the EHC 110 (hereinafter referred to as catalyst temperature) Tc. The catalyst temperature sensor 114 transmits a signal indicating the detected catalyst temperature Tc to the ECU 200.

  The catalyst temperature Tc may be directly detected by the catalyst temperature sensor 114. Alternatively, the catalyst temperature Tc may be estimated by the ECU 200 based on the temperature of a member near the EHC 110, the exhaust temperature upstream of the EHC 110, the exhaust temperature downstream of the EHC 110, or the operation history of the engine 10.

  Further, the engine 10 is provided with an engine rotation speed sensor 11. The engine rotation speed sensor 11 detects the rotation speed Ne (hereinafter referred to as engine rotation speed) Ne of the crankshaft 18 of the engine 10. The engine rotation speed sensor 11 transmits a signal indicating the detected engine rotation speed Ne to the ECU 200.

  Power split device 40 mechanically connects each of the three elements of drive shaft 16 for rotating drive wheel 80, crankshaft 18 of engine 10 and the rotation shaft of first MG 20. The power split device 40 enables transmission of power between the other two elements by using any one of the three elements described above as a reaction force element. The rotation shaft of second MG 30 is connected to drive shaft 16.

  Power split device 40 is a planetary gear mechanism including sun gear 50, pinion gear 52, carrier 54, and ring gear 56. Pinion gear 52 meshes with each of sun gear 50 and ring gear 56. The carrier 54 supports the pinion gear 52 so as to be capable of rotating, and is connected to the crankshaft 18 of the engine 10. Sun gear 50 is coupled to the rotation shaft of first MG 20. Ring gear 56 is coupled to the rotation shaft of second MG 30 and reduction gear 58 via drive shaft 16.

  Reducer 58 transmits the power from power split device 40 and second MG 30 to drive wheels 80. Reducer 58 transmits the reaction force from the road surface received by drive wheels 80 to power split device 40 and second MG 30.

  The PCU 60 includes a plurality of switching elements. PCU 60 converts the DC power stored in battery 70 into AC power for driving first MG 20 and second MG 30 by controlling the on / off operation of the switching element. PCU 60 includes a converter and an inverter (both not shown) controlled based on control signal S2 from ECU 200. The converter boosts the voltage of the DC power received from battery 70 and outputs it to the inverter. The inverter converts the DC power output from the converter into AC power and outputs the AC power to first MG 20 and / or second MG 30. Thus, first MG 20 and / or second MG 30 are driven using the electric power stored in battery 70. The inverter converts AC power generated by the first MG 20 and / or the second MG 30 into DC power and outputs the DC power to the converter. The converter steps down the voltage of the DC power output from the inverter and outputs the voltage to battery 70. Thereby, battery 70 is charged using the electric power generated by first MG 20 and / or second MG 30. The converter may be omitted.

  The battery 70 is a power storage device and is a rechargeable DC power source. As the battery 70, for example, a secondary battery such as nickel metal hydride or lithium ion is used. The voltage of the battery 70 is about 200V, for example. Battery 70 may be charged using electric power supplied from an external power source (not shown) in addition to being charged using electric power generated by first MG 20 and / or second MG 30 as described above. The battery 70 is not limited to a secondary battery, but may be a battery capable of generating a DC voltage, such as a capacitor, a solar battery, or a fuel battery.

  The battery 70 is provided with a battery temperature sensor 156, a current sensor 158, and a voltage sensor 160.

  Battery temperature sensor 156 detects battery temperature TB of battery 70. Battery temperature sensor 156 transmits a signal indicating battery temperature TB to ECU 200.

  Current sensor 158 detects current IB of battery 70. Current sensor 158 transmits a signal indicating current IB to ECU 200.

  Voltage sensor 160 detects voltage VB of battery 70. Voltage sensor 160 transmits a signal indicating voltage VB to ECU 200.

  ECU 200 estimates the remaining capacity of battery 70 (described as SOC (State of Charge) in the following description) based on current IB of battery 70, voltage VB, and battery temperature TB. ECU 200 estimates, for example, OCV (Open Circuit Voltage) based on current IB, voltage VB, and battery temperature TB, and estimates the SOC of battery 70 based on the estimated OCV and a predetermined map. Also good. Alternatively, ECU 200 may estimate the SOC of battery 70 by, for example, integrating the charging current and discharging current of battery 70.

  Charging device 78 charges battery 70 using electric power supplied from external power supply 302 when charging plug 300 is attached to vehicle 1. Charging plug 300 is connected to one end of charging cable 304. The other end of charging cable 304 is connected to external power supply 302. The positive terminal of the charging device 78 is connected to a power supply line PL that connects the positive terminal of the PCU 60 and the positive terminal of the battery 70. The negative terminal of the charging device 78 is connected to the earth line NL that connects the negative terminal of the PCU 60 and the negative terminal of the battery 70.

  The first resolver 12 is provided in the first MG 20. The first resolver 12 detects the rotational speed Nm1 of the first MG 20. The first resolver 12 transmits a signal indicating the detected rotation speed Nm1 to the ECU 200.

  The second resolver 13 is provided in the second MG 30. The second resolver 13 detects the rotational speed Nm2 of the second MG 30. The second resolver 13 transmits a signal indicating the detected rotation speed Nm2 to the ECU 200.

  A wheel speed sensor 14 is provided on a drive shaft 82 that connects the speed reducer 58 and the drive wheel 80. The wheel speed sensor 14 detects the rotational speed Nw of the drive wheel 80. The wheel speed sensor 14 transmits a signal indicating the detected rotation speed Nw to the ECU 200. ECU 200 calculates vehicle speed V based on the received rotational speed Nw. ECU 200 may calculate vehicle speed V based on rotation speed Nm2 of second MG 30 instead of rotation speed Nw.

  The accelerator pedal 162 is provided in the driver's seat. The accelerator pedal 162 is provided with a pedal stroke sensor 164. The pedal stroke sensor 164 detects the stroke amount AP of the accelerator pedal 162. The pedal stroke sensor 164 transmits a signal indicating the stroke amount AP to the ECU 200. Instead of the pedal stroke sensor 164, an accelerator pedal depression force sensor for detecting the occupant's depression force on the accelerator pedal 162 may be used.

  ECU 200 generates a control signal S1 for controlling engine 10, and outputs the generated control signal S1 to engine 10. ECU 200 also generates a control signal S2 for controlling PCU 60 and outputs the generated control signal S2 to PCU 60. The ECU 200 generates a control signal S3 for controlling the power supply circuit 112, and outputs the generated control signal S3 to the power supply circuit 112.

  The ECU 200 controls the entire hybrid system, that is, the charging / discharging state of the battery 70 and the operating states of the engine 10, the first MG 20 and the second MG 30 so that the vehicle 1 can operate most efficiently by controlling the engine 10, the PCU 60, and the like. .

  ECU 200 calculates required power Pv corresponding to stroke amount AP of accelerator pedal 162 provided in the driver's seat. ECU 200 controls the torque of first MG 20 and second MG 30 and the output of engine 10 in accordance with the calculated required power Pv.

  In the vehicle 1 having the above-described configuration, when only the second MG 30 is running when starting or running at a low speed and the efficiency of the engine 10 is poor. Further, during normal travel, for example, the power split device 40 divides the power of the engine 10 into two paths of power. The drive wheel 80 is directly driven by one power. The first MG 20 is driven with the other power to generate power. At this time, ECU 200 drives second MG 30 using the generated electric power. In this way, driving of the driving wheel 80 is performed by driving the second MG 30.

  When the vehicle 1 decelerates, the second MG 30 driven by the rotation of the drive wheels 80 functions as a generator to perform regenerative braking. The electric power recovered by regenerative braking is stored in the battery 70. ECU 200 increases the output of engine 10 to increase the amount of power generated by first MG 20 when the SOC of battery 70 decreases and charging is particularly necessary. Thereby, the SOC of the battery 70 is increased. In addition, the ECU 200 may perform control to increase the driving force from the engine 10 as necessary even during low-speed traveling. For example, the battery 70 needs to be charged as described above, an auxiliary machine such as an air conditioner is driven, or the temperature of the cooling water of the engine 10 is raised to a predetermined temperature.

  During the operation of the engine 10 of the vehicle 1 having the above-described configuration, the exhaust gas passes through the catalyst 154 in the EHC 110, so that the center side of the catalyst 154 is in a high temperature state, and the outer peripheral side of the catalyst 154 Has a temperature distribution such that the temperature is low.

  Specifically, when the exhaust gas passes through the catalyst 154, as shown in FIG. 2, the temperature of the catalyst 154 increases toward the center, and the temperature of the catalyst 154 decreases toward the outer periphery. The temperature distribution is such that the concentric circles are isotherms. This is because the exhaust gas flow rate increases toward the center of the catalyst 154, and the exhaust gas flow rate decreases as the catalyst 154 moves toward the outer periphery, and heat is radiated from the exhaust pipe.

  As a result, as shown in FIG. 3, the temperature difference ΔTc () between the temperature Tc (0) at the center in the catalyst 154 and the temperature Tc (1) in the vicinity of the electrode at the outer peripheral portion (just below the connection portion 150). Tc (0) -Tc (1)) occurs. In particular. Since the temperature difference ΔTc increases as the temperature change due to acceleration of the vehicle 1 increases, thermal stress due to the temperature difference ΔTc may be generated in the catalyst 154.

  Therefore, the present embodiment is characterized in that ECU 200 executes energization control in which current is supplied to positive electrode 116 and negative electrode 118 when exhaust gas from engine 10 passes through catalyst 154 in EHC 110. Have

  FIG. 4 shows a functional block diagram of ECU 200 mounted on vehicle 1 according to the present embodiment. ECU 200 includes a required power calculation unit 202, a temperature difference estimation unit 204, a temperature difference determination unit 206, an energization pattern determination unit 208, and an energization control unit 210.

  The required power calculation unit 202 calculates the required power Pe for the engine 10 based on the stroke amount AP of the accelerator pedal 162, the vehicle speed V, and the gradient of the road surface.

  The required power calculation unit 202 calculates the acceleration requested by the driver from the stroke amount AP of the accelerator pedal 162, for example. The required power calculation unit 202 calculates the required power Pv for the vehicle 1 to achieve the acceleration calculated based on the current vehicle speed V and the road surface gradient. Required power calculation unit 202 calculates required power Pe for engine 10 by subtracting power Pm that can be output using second MG 30 from required power Pv for vehicle 1. The required power calculation unit 202 calculates the required power Pe for the engine 10 using a predetermined map indicating the relationship between the stroke amount AP of the accelerator pedal 162, the vehicle speed V, the road surface gradient, and the required power Pe for the engine 10. May be. The predetermined map is a map in which the relationship among the stroke amount AP, the vehicle speed V, the road surface gradient, and the required power Pe for the engine 10 is adapted by experiments or the like.

  The temperature difference estimation unit 204 estimates the temperature difference ΔTc from the center of the catalyst 154 to the vicinity immediately below the electrode based on the catalyst temperature Tc and the required power Pe for the engine 10 calculated by the required power calculation unit 202.

  The temperature difference estimation unit 204 may estimate the temperature difference ΔTc using a predetermined map indicating the relationship between the required power Pe for the engine 10, the catalyst temperature Tc, and the temperature difference ΔTc. The predetermined map is a map in which the relationship among the required power Pe for the engine 10, the catalyst temperature Tc, and the temperature difference ΔTc is adapted by experiments or the like.

  The temperature difference estimation unit 204 calculates the thermal energy given to the catalyst 154 from the required power Pe for the engine 10, and based on the calculated thermal energy and the current catalyst temperature Tc, You may estimate the temperature difference (DELTA) Tc which arises between.

  In the present embodiment, the temperature difference ΔTc from the center of the catalyst 154 to the vicinity immediately below the electrode means the peak value of the temperature difference ΔTc.

  FIG. 5 shows a change between the temperature at the center of the catalyst 154 and the temperature immediately below the electrode when the accelerator pedal 162 is depressed at time T (0). For example, when the accelerator pedal 162 is depressed until the stroke amount AP reaches AP (0), the required power Pe for the engine 10 starts to increase at time T (0) as shown by the thick solid line in FIG. Suppose that the required power Pe (0) corresponding to the stroke amount AP (0) converges.

  In this case, as shown by a thin solid line in FIG. 5, the temperature Tc1 at the center of the catalyst 154 starts to rise at time T (0), and the temperature Tc1 (Tc1) that also has the temperature Tc1 according to the convergence of the required power Pe. Converges to 0).

  As shown by a thin broken line in FIG. 5, the temperature Tc2 immediately below the electrode of the catalyst 154 starts to rise with an amount of increase smaller than Tc1 at time T (0), and then time elapses with respect to the temperature Tc1. It changes to approach.

  As a result, the difference ΔTc (solid line in the lower graph of FIG. 5) between the temperature Tc1 and the temperature Tc2 starts to increase at the time T (0), and then increases at the time T (1) at the peak value ΔTcp (0). And decreases after time T (1).

  The temperature difference estimation unit 204 estimates the above-described peak value as the temperature difference ΔTc based on the catalyst temperature Tc and the required power Pe for the engine 10.

  Further, for example, when the accelerator pedal 162 is depressed until the stroke amount AP of the accelerator pedal 162 becomes AP (1) smaller than AP (0), the required power Pe for the engine 10 is as shown by a thick broken line in FIG. The increase starts at T (0) and converges to the required power Pe (1) (<Pe (0)) corresponding to the stroke amount AP (1).

  In this case, the temperature Tc1 ′ at the center of the catalyst 154 starts to rise at time T (0) as shown by the one-dot chain line in FIG. 5, and the temperature Tc1 ′ is also at a temperature corresponding to the convergence of the required power Pe. It converges to Tc1 ′ (0) (<Tc1 (0)).

  Further, the temperature Tc2 ′ immediately below the electrode of the catalyst 154 starts to rise at an amount of increase smaller than Tc1 ′ at time T (0) as shown by the two-dot chain line in FIG. Change over time.

  As a result, the difference ΔTc ′ (the broken line in the lower graph of FIG. 5) between the temperature Tc1 ′ and the temperature Tc2 ′ starts to increase at the time T (0) and then increases at the time T (1). (1), and decreases after time T (1).

  At this time, the temperature Tc1 'has a smaller temperature rise at time T (0) than the temperature Tc1, and the converging temperature Tc1' (0) is also lower than the temperature Tc1 (0). Further, the temperature Tc2 ′ has a smaller temperature rise at time T (0) than the temperature Tc2, and then approaches Tc1 ′ (0) smaller than Tc1 (0) as time elapses thereafter. Change.

  Therefore, the peak value ΔTcp (1) is smaller than ΔTc (0). That is, the temperature difference in the catalyst 154 increases (the peak value increases) as the amount of temperature increase in the catalyst 154 becomes steep (the required power Pe for the engine 10 increases).

  That is, when the required power Pe for the engine 10 is high, the temperature difference estimation unit 204 estimates a higher value as the temperature difference ΔTc than when it is low.

  Note that the temperature difference estimation unit 204 may acquire the catalyst temperature Tc from the catalyst temperature sensor 114, for example. Alternatively, the temperature difference estimation unit 204 calculates the variation amount of the catalyst temperature Tc based on the temperature of the member near the EHC 110, the exhaust temperature upstream of the catalyst 154, the exhaust temperature downstream of the catalyst 154, or the operation history of the engine 10. The catalyst temperature Tc may be estimated by estimating and integrating the estimated fluctuation amount.

  The temperature difference determination unit 206 determines whether or not the temperature difference ΔTc estimated by the temperature difference estimation unit 204 is larger than the threshold value ΔTc (0). The threshold value ΔTc (0) is a threshold value for determining whether or not the catalyst 154 needs to be protected. The threshold value ΔTc (0) is a value for determining that the temperature difference does not affect the shape of the catalyst due to thermal stress, for example, and is adapted by experiment.

  Note that the temperature difference determination unit 206 may turn on the temperature difference determination flag when, for example, the temperature difference ΔTc estimated by the temperature difference estimation unit 204 is larger than the threshold value ΔTc (0).

  The energization pattern determination unit 208 determines an energization pattern based on the SOC of the battery 70, the required power Pe for the engine 10, and the catalyst temperature Tc. The energization pattern determination unit 208 energizes using, for example, a predetermined map indicating the relationship between the required power Pe for the engine 10, the catalyst temperature Tc, the energization power to the positive electrode 116 and the negative electrode 118, and the energization time. A pattern may be determined.

  The predetermined map is a map in which the relationship between the required power Pe for the engine 10, the catalyst temperature Tc, the energization power and the energization time is adapted by experiments or the like. In addition, the energization pattern determination unit 208 may correct the energization power or the energization time so that, for example, when the SOC of the battery 70 is low, the energization power or the energization time is reduced as compared with a high case. Alternatively, for example, when the SOC of the battery 70 is close to the lower limit value (when the SOC is lower than the threshold value (> lower limit value)), the energization pattern determination unit 208 moves to the positive electrode 116 and the negative electrode 118. It may be determined not to execute the energization control. For example, when the temperature difference determination flag is on, the energization pattern determination unit 208 determines an energization pattern based on the SOC of the battery 70, the required power Pe for the engine 10, and the catalyst temperature Tc. Also good.

  Further, as shown in FIG. 5, at least the energization time is longer than the time from the time when the temperature difference ΔTc starts to increase (time T (0)) to the time when the peak value is reached (time (T1)). It is desirable to be determined.

  The energization pattern is not limited to being determined based on the SOC of the battery 70, the required power Pe for the engine 10, and the catalyst temperature Tc.

  The energization control unit 210 performs energization control according to the determined energization pattern. The energization control unit 210 controls the PCU 60 and the power supply circuit 112 so that the determined energization power is supplied, and turns on the relay built in the power supply circuit 112 until the determined energization time elapses. After the energization time has elapsed, the relay built in the power supply circuit 112 is turned off.

  In the present embodiment, the required power calculation unit 202, the temperature difference estimation unit 204, the temperature difference determination unit 206, the energization pattern determination unit 208, and the energization control unit 210 are all stored in the memory by the CPU of the ECU 200. Although the description will be made assuming that the program functions as software, which is realized by executing the program, it may be realized by hardware. Such a program is recorded on a storage medium and mounted on the vehicle.

  With reference to FIG. 6, a control structure of a program executed by ECU 200 mounted on vehicle 1 according to the present embodiment will be described.

  In step (hereinafter, step is referred to as S) 100, ECU 200 obtains stroke amount AP of accelerator pedal 162 from pedal stroke sensor 164.

  In S102, ECU 200 calculates required power Pe for engine 10. Since the calculation method of required power Pe is as described above, detailed description thereof will not be repeated.

  In S104, ECU 200 acquires catalyst temperature Tc from catalyst temperature sensor 114. In S106, ECU 200 estimates temperature difference ΔTc between the central portion of catalyst 154 and the area immediately below the electrode based on calculated required power Pe and catalyst temperature Tc.

  In S108, ECU 200 determines whether or not estimated temperature difference ΔTc is larger than threshold value ΔTc (0). If estimated temperature difference ΔTc is larger than threshold value ΔTc (0) (YES in S108), the process proceeds to S110. If not (NO in S108), the process returns to S100.

  In S110, ECU 200 determines an energization pattern based on SOC of battery 70, required power Pe for engine 10 and catalyst temperature Tc. In S112, ECU 200 executes energization control according to the determined energization pattern.

  The operation of ECU 200 mounted on the vehicle according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIGS. 7 and 8.

  For example, while the vehicle 1 is traveling, the stroke amount AP of the accelerator pedal 162 is acquired (S100), the required power Pe for the engine 10 is calculated (S102), and the calculated required power Pe and the catalyst temperature sensor 114 are calculated. Based on the acquired catalyst temperature Tc (S104), the temperature difference ΔTc is estimated (S106).

  When estimated temperature difference ΔTc is equal to or smaller than threshold value ΔTc (0) (NO in S108), energization control is not executed. On the other hand, when estimated temperature difference ΔTc is larger than threshold value ΔTc (0) (YES in S108), based on SOC of battery 70, required power Pe for engine 10, and catalyst temperature Tc. An energization pattern is determined (S110). And energization control is performed according to the determined energization pattern (S112).

  For example, when the energization control is executed when the exhaust gas does not pass through the catalyst 154 such as when the engine 10 is stopped, a current flows uniformly to the catalyst 154. At this time, heat is trapped in the vicinity of the positive electrode 116 and the negative electrode 118 of the catalyst 154. Therefore, as shown in FIG. 7, the temperature increases near the positive electrode 116 and the negative electrode 118. On the other hand, in the intermediate part between the positive electrode 116 and the negative electrode 118, the temperature distribution is lower than the vicinity of the positive electrode 116 or the vicinity of the negative electrode 118 due to heat radiation from the exhaust pipe.

  Therefore, when the exhaust gas passes through the catalyst 154, in the vicinity of the positive side electrode 116 and the negative side electrode 118 where the temperature becomes low when the exhaust gas passes, the temperature rises due to the execution of energization control. As a result, as shown by the solid line in FIG. 8, the temperature distribution is such that the temperature is substantially constant from the center of the catalyst 154 to the outer periphery directly under the electrode.

  8 indicates the temperature distribution in the catalyst 154 when the exhaust gas passes through the catalyst 154. A one-dot chain line in FIG. 8 indicates a temperature distribution in the catalyst 154 when the energization control is executed when the exhaust gas does not pass through the catalyst 154.

  As described above, according to the vehicle 1 according to the present embodiment, the exhaust gas is exhausted by combining the temperature distribution obtained by energizing the catalyst 154 formed of a uniform material and the temperature distribution when the exhaust gas passes. A portion that is difficult to warm in the catalyst when the gas passes can be heated by energization control. As a result, the expansion of the temperature difference in the catalyst can be effectively suppressed. Therefore, when the exhaust gas passes through the catalyst, it is possible to provide a vehicle that suppresses the expansion of the difference in temperature distribution inside the catalyst using the electric heating catalyst.

  Further, when the temperature difference ΔTc from the center of the catalyst 154 to the vicinity immediately below the electrode is estimated to be equal to or less than the threshold value, unnecessary power consumption can be suppressed by not executing the energization control.

  Further, by forming the catalyst from a uniform material and providing the positive electrode 116 and the negative electrode 118 having a predetermined shape on the outer periphery of the catalyst 154, a temperature distribution during energization as shown in FIG. 8 is obtained. be able to. As a result, when the exhaust gas passes through the catalyst, it is possible to suppress the temperature increase in the catalyst.

  In the present embodiment, the positive side electrode 116 and the negative side such that the temperature distribution from the central part to the outer peripheral part directly below the electrode is substantially constant with respect to the temperature distribution in the catalyst 154 when exhaust gas passes. Although it has been described that the shape of the electrode 118 is selected, the temperature distribution in the catalyst 154 when exhaust gas passes changes depending on the configuration of the engine 10. For this reason, it is desirable to select optimal shapes of the positive electrode 116 and the negative electrode 118 so that the temperature distribution from the central portion to the outer periphery immediately below the electrodes is substantially constant for each configuration of the engine 10.

  Further, the temperature difference ΔTc of the temperature distribution in the catalyst 154 when the exhaust gas passes should be smaller than the threshold value ΔTc (0) by the energization control. In particular, the shapes of the positive electrode 116 and the negative electrode 118 are The shape is not limited to that shown in FIG.

  The vehicle to which the present invention is applied is not limited to the hybrid vehicle of the type shown in FIG. 1, but may be a hybrid vehicle of another type (for example, a series type or a parallel type). Furthermore, the vehicle to which the present invention is applied may be a vehicle on which the engine 10 is mounted, and may be applied to a vehicle using only the engine as a drive source in addition to the hybrid vehicle.

  In the present embodiment, ECU 200 has been described as estimating temperature difference ΔTc based on required power Pe for engine 10 and catalyst temperature Tc. For example, instead of required power Pe for engine 10, ECU 200 applies to engine 10. The temperature difference ΔTc may be estimated based on the required torque Te, the exhaust gas temperature, or the exhaust gas flow rate.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 hybrid vehicle, 10 engine, 11 engine rotational speed sensor, 12, 13 resolver, 14 wheel speed sensor, 16 drive shaft, 18 crankshaft, 20, 30 MG, 40 power split device, 50 sun gear, 52 pinion gear, 54 carrier, 56 ring gear, 58 reduction gear, 60 PCU, 70 battery, 78 charging device, 80 drive wheel, 82 drive shaft, 102 cylinder, 104 fuel injection device, 106 exhaust manifold, 108 exhaust passage, 112 power supply circuit, 114 catalyst temperature sensor, 116 Positive electrode, 118 Negative electrode, 150 Connection portion, 152 Cross section, 154 Catalyst, 156 Battery temperature sensor, 158 Current sensor, 160 Voltage sensor, 162 Accelerator pedal, 164 Pedal stroke sensor, 200 ECU, 202 required power calculation unit, 204 temperature difference estimation unit, 206 temperature difference determination unit, 208 energization pattern determination unit, 210 energization control unit, 300 charging plug, 302 external power source, 304 charging cable.

Claims (7)

Engine,
An exhaust purification device including a catalyst formed in a uniform material and provided in an exhaust pipe of the engine; and an electrode attached to an outer peripheral portion of the catalyst for heating the catalyst;
A vehicle comprising: a control device for performing energization control for causing a current to flow through the electrode when exhaust gas from the engine passes through the catalyst.   The vehicle according to claim 1, wherein the control device determines whether to execute the energization control based on an operating state of the engine and a temperature of the catalyst.   The controller is configured to apply the energization when a state of the catalyst based on an operating state of the engine and a temperature of the catalyst is a state where a difference in temperature in a temperature distribution in the catalyst is larger than a threshold value. The vehicle according to claim 2, wherein control is executed.   The vehicle according to claim 3, wherein the control device does not execute the energization control when the state of the catalyst is in a state where the height difference is smaller than the threshold value.   The vehicle according to any one of claims 1 to 4, wherein the control device determines energization power and energization time based on an operating state of the engine and a temperature of the catalyst when the energization control is executed.   The vehicle according to any one of claims 1 to 5, wherein the uniform material is a single material. The catalyst has a cylindrical shape,
The electrode includes a connection portion provided on the outer peripheral surface of the catalyst and connected to a power source, and a cross-sectional portion having a bow-shaped cross section that partially covers the outer peripheral surface of the catalyst around the connection portion. A first electrode;
A second electrode having the same shape as the first electrode and provided at a position facing the first electrode with the catalyst interposed therebetween,
The vehicle according to any one of claims 1 to 5, wherein the cross-sectional portion is formed so as to be thinner as the position is farther from the connection portion.

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