JP2010236544A - Exhaust emission control device and method for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve purifying efficiency of exhaust gas in an exhaust emission control device for a hybrid vehicle. <P>SOLUTION: This exhaust emission control device (204 and 206) for the hybrid vehicle includes an electric heating type catalyst (204 and 206) heated by energization, a downstream catalyst (205) provided downstream of the electric heating type catalyst, a downstream catalyst temperature specifying means (205a) for specifying the temperature of the downstream catalyst, and an energization amount controlling means (190) for controlling the energization amount of the electric heating type catalyst at startup of an internal combustion engine (150) so that the temperature of the electric heating type catalyst approaches a first target temperature determined according to the specified downstream catalyst temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device for a hybrid vehicle including an internal combustion engine and an electric motor.

  As a device of this type, in Patent Document 1 and the like, in a hybrid vehicle, when an engine start is requested due to a battery charging request, an electrocatalyst heater (so-called EHC: Electrically Heated Catalyst) is energized to A technique for starting the engine after the temperature reaches the activation temperature is disclosed. Patent Document 2 and the like disclose a technique for starting an engine by energizing EHC when the catalyst is at a low temperature in a hybrid vehicle. Patent Document 3 discloses a technique for energizing an EHC when starting an engine in a hybrid vehicle in a state where a state of charge (SOC) is reduced during traveling by an electric motor. .

  Patent Document 4 discloses a technique related to an internal combustion engine that includes an electrocatalyst heater on the upstream side of the exhaust system and a general catalyst such as cordierite on the downstream side of the exhaust system.

  Patent Document 5 discloses a hybrid vehicle control device that retards the ignition timing and then gradually advances the ignition timing when switching from so-called EV traveling to so-called hybrid traveling in a hybrid vehicle. Yes.

JP-A-8-338235 JP 2003-227366 A Japanese Patent Laid-Open No. 10-288028 JP-A-4-219413 Japanese Patent Laid-Open No. 2003-065124

  However, according to the above-described Patent Document 1 or the like, for example, in a plug-in hybrid vehicle (hereinafter referred to as “plug-in HV vehicle” as appropriate) where the opportunity to start the engine is not uniformly determined, the exhaust gas of the engine There arises a technical problem that it becomes difficult to sufficiently purify the water. This is because, in a plug-in HV vehicle that can be charged by a household power source, an opportunity to start the engine is determined according to, for example, the required amount of engine load and the state of charge. For this reason, in a vehicle having a low opportunity and frequency of starting an engine such as a plug-in HV vehicle, the catalyst cools during a period in which the engine is not started, and when the engine is started, the catalyst is warmed up sufficiently and quickly. This causes a technical problem that it is difficult to do.

  Accordingly, the present invention has been made in view of the above-described problems, for example, and an object of the present invention is to provide an exhaust gas purification apparatus and method for a hybrid vehicle that can improve exhaust gas purification efficiency.

  In order to solve the above-mentioned problems, an exhaust emission control device for a hybrid vehicle according to the present invention includes an electrically heated catalyst heated by energization, a downstream catalyst provided downstream of the electrically heated catalyst, and the downstream A downstream catalyst temperature specifying means for specifying the temperature of the side catalyst, and the temperature of the electrically heated catalyst approaches a first target temperature determined in accordance with the specified downstream catalyst temperature when the internal combustion engine is started. As described above, an energization amount control means for controlling the energization amount of the electrically heated catalyst is provided.

  A hybrid vehicle according to the present invention includes an internal combustion engine, an electric motor, a secondary battery that stores electric power for driving the electric motor and is charged and discharged as the vehicle travels, and an exhaust system of the internal combustion engine that is provided with an activation temperature. An exhaust gas purification apparatus according to the present invention that performs exhaust gas purification based on the above may be provided. In this hybrid vehicle, a type in which an internal combustion engine can serve as a vehicle drive source (so-called parallel type hybrid vehicle) and an internal combustion engine cannot be directly used as a vehicle drive source, and are mainly mounted for driving a generator. (A so-called series-type hybrid vehicle). Hybrid vehicles will continue to run in the event that the remaining capacity of the secondary battery that supplies power to the motor decreases, or when there is a possibility of sudden power consumption during acceleration or climbing, etc. The internal combustion engine is started because it is expected to be difficult. In a parallel hybrid vehicle, the internal combustion engine may be started in order to use the power of the internal combustion engine as the driving force of the vehicle during acceleration or climbing. When starting the internal combustion engine, it is necessary to heat the exhaust purification means prior to starting the internal combustion engine in order to reduce exhaust gas (or exhaust emission) emissions.

  In particular, in the exhaust emission control device for a hybrid vehicle according to the present invention, the electrically heated catalyst reaches an activation temperature when heated by energization, and purifies the exhaust gas of the internal combustion engine. Here, the electrically heated catalyst according to the present invention typically converts electrical energy into thermal energy in accordance with the amount of electricity supplied, that is, the amount of electrical energy supplied from the outside, and the converted heat. It means a catalyst that can change its temperature according to energy. This electrically heated catalyst means a catalyst that can purify the exhaust gas of an internal combustion engine by causing its temperature to reach the activation temperature. Typically, this electrically heated catalyst may consist of (i) a catalyst portion and (ii) a heating means for heating the catalyst portion by converting the supplied electrical energy into thermal energy. The downstream catalyst is provided downstream of the electrically heated catalyst, and purifies the exhaust gas of the internal combustion engine together with the electrically heated catalyst. Here, the “downstream side” according to the present invention is one of the directional concepts based on the direction of intake air flow, and in this case, means the side toward the outside air through the muffler. The downstream side catalyst temperature specifying means specifies the temperature of the downstream side catalyst. Here, “specific” according to the present invention typically means that the temperature of the downstream catalyst is directly or indirectly specified or indirectly from the range of some physical quantity or parameter indicating the temperature of the downstream catalyst described above. It means “estimate” or the like. In addition to or instead of this, the specification according to the present invention refers to “detection” and “detection” of the temperature of the downstream catalyst directly or indirectly from the range of some physical quantity or parameter indicating the temperature of the downstream catalyst described above. "Measuring" or the like. For example, when the internal combustion engine is started under the control of an energization amount control means such as a microprocessor, the temperature of the electrically heated catalyst approaches the first target temperature determined according to the specified downstream catalyst temperature. The energization amount supplied to the electrically heated catalyst is changed.

  In general, in an exhaust gas purification apparatus including the above-described electric heating catalyst (hereinafter referred to as EHC as appropriate), the electric heating catalyst can be warmed up by energization, but it is located downstream of the electric heating catalyst. It is technically difficult to properly warm up the downstream catalyst. In particular, in a plug-in hybrid vehicle (hereinafter referred to as a “plug-in HV vehicle” where the opportunity to start the internal combustion engine is not uniformly determined), for example, depending on the required load amount and the state of charge of the internal combustion engine. The opportunity to start the internal combustion engine is determined. For this reason, it becomes technically difficult to sufficiently purify the exhaust gas of the internal combustion engine by effectively using the downstream catalyst. Specifically, after the internal combustion engine is started, the thermal energy of the exhaust gas itself is transmitted to the downstream catalyst, and the thermal energy of the electrically heated catalyst is transmitted through the flow of the exhaust gas. However, in a vehicle with a low opportunity and frequency of starting an internal combustion engine such as a plug-in HV vehicle, the downstream catalyst cools during a period when the internal combustion engine is not started. It becomes technically difficult to warm up sufficiently and quickly.

  On the other hand, according to the present invention, under the control of the energization amount control means, the temperature of the electrically heated catalyst approaches the first target temperature determined according to the specified downstream catalyst temperature, The energization amount of the electrically heated catalyst is changed. As a result, it is possible to achieve both the optimal electric heating catalyst power control (that is, energization control) and the improvement of the exhaust gas purification efficiency according to the temperature of the downstream catalyst. It is. Typically, under the control of the energization amount control means, (i) the energization amount of the electrically heated catalyst is changed so that the first target temperature becomes higher as the specified downstream catalyst temperature becomes lower. This is because the total amount of catalyst capacity indicating the degree of catalyst purification capacity in the exhaust purification system, that is, the sum of the catalyst capacity of the electrically heated catalyst and the catalyst capacity of the downstream catalyst is the internal combustion engine mounted on the hybrid vehicle. It is determined according to the amount of exhaust gas when the engine is operating at a high load. Accordingly, when the temperature of the downstream catalyst is low, the first target temperature of the electrically heated catalyst is made higher, and the ratio of the catalyst capacity of the electrically heated catalyst is further increased in the total amount of the catalyst capacity. It is possible to compensate for the decrease in the catalyst capacity and to effectively improve the purification efficiency in the exhaust emission control device. In addition, when the temperature of the downstream catalyst is low, the first target temperature of the electrically heated catalyst is made higher, and the heat energy of the electrically heated catalyst is increased in a larger amount via the flow of the exhaust gas. By transmitting it to the catalyst, it is possible to promote the activation of the downstream side catalyst and to effectively improve the purification efficiency in the exhaust purification system.

  On the other hand, (ii) the energization amount of the electrically heated catalyst is changed so that the first target temperature decreases as the identified downstream catalyst temperature increases. Typically, as the stop time of the internal combustion engine becomes shorter, the temperature of the downstream catalyst tends to increase. As a result, when the temperature of the downstream catalyst is high, the first target temperature of the electrically heated catalyst is lowered, and the ratio of the capacity of the electrically heated catalyst in the total amount of the catalyst capacity is further reduced, for example, a battery or the like It is possible to reduce the amount of energization from the secondary battery to the electrically heated catalyst and reduce the consumption of the secondary battery. In addition, the thermal energy of the electrically heated catalyst is effectively prevented from being excessively transmitted to the downstream catalyst through the exhaust gas flow, and the temperature of the downstream catalyst is excessively increased. Can be reduced.

  In particular, according to the present invention, even when the temperature of the downstream catalyst is low, the catalyst capacity of the downstream catalyst can be supplemented by the electrically heated catalyst as described above. The exhaust gas can be more effectively purified when starting the internal combustion engine in a hybrid vehicle that has a low opportunity and frequency of starting the internal combustion engine and has a high tendency to lower the temperature of the downstream catalyst. In this way, by changing the first target temperature of the electrically heated catalyst in accordance with the temperature of the downstream catalyst and changing the degree of activation of the downstream catalyst, the electrically heated catalyst and the downstream catalyst are By cooperating and organically acting, it is possible to realize both the electric power control of the highly efficient electric heating type catalyst and the improvement of the exhaust gas purification efficiency.

  In one aspect of the exhaust gas purifying apparatus for a hybrid vehicle of the present invention, the energization amount control means is configured such that (i) the energization is performed such that the first target temperature increases as the identified downstream catalyst temperature decreases. (Ii) The energization amount is changed so that the first target temperature decreases as the identified downstream catalyst temperature increases.

  According to this aspect, under the control of the energization amount control means, (i) the energization amount of the electrically heated catalyst is changed so that the first target temperature increases as the specified downstream catalyst temperature decreases. . Accordingly, when the temperature of the downstream catalyst is low, the first target temperature of the electrically heated catalyst is made higher, and the ratio of the catalyst capacity of the electrically heated catalyst is further increased in the total amount of the catalyst capacity. It is possible to compensate for the decrease in the catalyst capacity and to effectively improve the purification efficiency in the exhaust emission control device. In addition, when the temperature of the downstream catalyst is low, the first target temperature of the electrically heated catalyst is made higher, and the heat energy of the electrically heated catalyst is increased in a larger amount via the flow of the exhaust gas. By transmitting it to the catalyst, it is possible to promote the activation of the downstream side catalyst and to effectively improve the purification efficiency in the exhaust purification system.

  On the other hand, (ii) the energization amount of the electrically heated catalyst is changed so that the first target temperature decreases as the identified downstream catalyst temperature increases. As a result, when the temperature of the downstream catalyst is high, the first target temperature of the electrically heated catalyst is lowered, and the ratio of the capacity of the electrically heated catalyst in the total amount of the catalyst capacity is further reduced, for example, a battery or the like It is possible to reduce the amount of energization from the secondary battery to the electrically heated catalyst and reduce the consumption of the secondary battery. In addition, the thermal energy of the electrically heated catalyst is effectively prevented from being excessively transmitted to the downstream catalyst through the exhaust gas flow, and the temperature of the downstream catalyst is excessively increased. Can be reduced.

  According to another aspect of the exhaust gas purification apparatus for a hybrid vehicle of the present invention, the electric power supply means (for example, a secondary battery) for supplying electric power to the electric heating catalyst and the specified downstream catalyst temperature Determining means for determining a first target temperature, wherein the energization amount control means supplies the electric power supply so as to supply a predetermined energization amount corresponding to the determined first target temperature to the electrically heated catalyst. Control means.

  According to this aspect, by supplying a predetermined energization amount corresponding to the determined first target temperature to the electrically heated catalyst, it is possible to achieve highly efficient and highly accurate electric power control of the electrically heated catalyst. Is possible.

  Another aspect of the exhaust gas purifying apparatus for a hybrid vehicle of the present invention further includes a stop time specifying means for specifying a stop time of the internal combustion engine, wherein the energization amount control means is (i) the specified stop time is long. Accordingly, the energization amount is changed so that the first target temperature becomes higher, and (ii) the energization amount is changed so that the first target temperature becomes lower as the specified stop time becomes shorter. .

  According to this aspect, typically, under the control of the energization amount control means, (i) the energization amount of the electrically heated catalyst increases so that the first target temperature becomes higher as the specified stop time becomes longer. Changed. This is because, as described above, the total amount of catalyst capacity indicating the degree of catalyst purification capacity in the exhaust purification system, that is, the sum of the catalyst capacity of the electrically heated catalyst and the catalyst capacity of the downstream catalyst, is determined by the hybrid vehicle. It is determined according to the amount of exhaust gas when the mounted internal combustion engine is operating at a high load. Thereby, when the stop time of the internal combustion engine is long, the first target temperature of the electrically heated catalyst is made higher, and the ratio of the catalyst capacity of the electrically heated catalyst is further increased in the total amount of the catalyst capacity, whereby the downstream catalyst It is possible to compensate for the decrease in the catalyst capacity and to effectively improve the purification efficiency in the exhaust purification system. In addition, when the stop time of the internal combustion engine is long, the first target temperature of the electrically heated catalyst is made higher, and the heat energy of the electrically heated catalyst is increased in a larger amount through the flow of the exhaust gas downstream. By transmitting it to the catalyst, it is possible to promote the activation of the downstream side catalyst and to effectively improve the purification efficiency in the exhaust purification system.

  On the other hand, (ii) as the specified stop time becomes shorter, the energization amount of the electrically heated catalyst is changed so that the first target temperature becomes lower. Typically, as the stop time of the internal combustion engine becomes shorter, the temperature of the downstream catalyst tends to increase. Thereby, when the stop time of the internal combustion engine is short, the first target temperature of the electrically heated catalyst is made lower, and the ratio of the capacity of the electrically heated catalyst is further reduced in the total amount of the catalyst capacity, for example, a battery or the like It is possible to reduce the amount of energization from the secondary battery to the electrically heated catalyst and reduce the consumption of the secondary battery. In addition, the thermal energy of the electrically heated catalyst is effectively prevented from being excessively transmitted to the downstream catalyst through the exhaust gas flow, and the temperature of the downstream catalyst is excessively increased. Can be reduced.

  In particular, according to the present invention, even when the temperature of the downstream catalyst is low, the catalyst capacity of the downstream catalyst can be supplemented by the electrically heated catalyst as described above. The exhaust gas can be more effectively purified when starting the internal combustion engine in a hybrid vehicle that has a low opportunity and frequency of starting the internal combustion engine and has a high tendency to lower the temperature of the downstream catalyst.

  Thus, the electric heating catalyst and the downstream catalyst are changed by changing the first target temperature of the electric heating catalyst and changing the degree of activation of the downstream catalyst according to the length of the stop time of the internal combustion engine. Can be realized in a coordinated and organic manner, and it is possible to achieve both the optimum electric power control of the highly efficient electric heating catalyst and the improvement of the exhaust gas purification efficiency.

  In order to solve the above problems, a second exhaust gas purification apparatus for a hybrid vehicle according to the present invention includes an electrically heated catalyst heated by energization, and a downstream catalyst provided downstream of the electrically heated catalyst. , Downstream catalyst temperature specifying means for specifying the temperature of the downstream catalyst, the specified downstream catalyst temperature, and the temperature change characteristics of the electrically heated catalyst (typically, the degree of temperature decrease with time) More typically, the energization amount for controlling the energization amount of the electrically heated catalyst so that the temperature of the electrically heated catalyst approaches the second target temperature determined in accordance with the temperature that decreases according to the unit time). Control means.

  According to the second exhaust emission control device for a hybrid vehicle of the present invention, the temperature of the electrically heated catalyst is determined by the specified downstream catalyst temperature and the temperature change characteristic of the electrically heated catalyst under the control of the energization amount control means. The energization amount of the electrically heated catalyst is changed so as to approach the second target temperature determined according to the above. As a result, the power control (that is, energization control) of the highly efficient electric heating catalyst according to the temperature of the downstream catalyst and the temperature change characteristic of the electric heating catalyst and the improvement of the exhaust gas purification efficiency are achieved. It is possible to achieve both.

  Typically, under the control of the energization amount control means, (i) the energization amount of the electrically heated catalyst is changed so that the second target temperature becomes higher as the specified downstream catalyst temperature becomes lower. This is because the total amount of catalyst capacity indicating the degree of catalyst purification capacity in the exhaust purification system, that is, the sum of the catalyst capacity of the electrically heated catalyst and the catalyst capacity of the downstream catalyst is the internal combustion engine mounted on the hybrid vehicle. It is determined according to the amount of exhaust gas when the engine is operating at a high load. Accordingly, when the temperature of the downstream catalyst is low, the second target temperature of the electrically heated catalyst is made higher, and the ratio of the catalyst capacity of the electrically heated catalyst is further increased in the total amount of the catalyst capacity. It is possible to compensate for the decrease in the catalyst capacity and to effectively improve the purification efficiency in the exhaust emission control device. In addition, when the temperature of the downstream catalyst is low, the second target temperature of the electrically heated catalyst is made higher, and the heat energy of the electrically heated catalyst is increased in a larger amount via the flow of the exhaust gas. By transmitting it to the catalyst, it is possible to promote the activation of the downstream side catalyst and to effectively improve the purification efficiency in the exhaust purification system.

  On the other hand, (ii) as the specified downstream catalyst temperature increases, the energization amount of the electrically heated catalyst is changed so that the second target temperature decreases. Typically, as the stop time of the internal combustion engine becomes shorter, the temperature of the downstream catalyst tends to increase. Thereby, when the temperature of the downstream catalyst is high, the second target temperature of the electrically heated catalyst is made lower, and the ratio of the capacity of the electrically heated catalyst in the total amount of the catalyst capacity is further reduced, for example, a battery or the like It is possible to reduce the amount of energization from the secondary battery to the electrically heated catalyst and reduce the consumption of the secondary battery. In addition, the thermal energy of the electrically heated catalyst is effectively prevented from being excessively transmitted to the downstream catalyst through the exhaust gas flow, and the temperature of the downstream catalyst is excessively increased. Can be reduced.

  In particular, according to the second exhaust gas purification apparatus for a hybrid vehicle according to the present invention, it is determined according to the temperature change characteristic of the electrically heated catalyst in addition to the specified downstream catalyst temperature under the control of the energization amount control means. The energization amount of the electrically heated catalyst is changed so that the temperature of the electrically heated catalyst approaches the second target temperature. Here, the temperature change characteristic according to the present invention means the degree of change when the temperature changes with time in the property related to temperature change of the electrically heated catalyst. Typically, the temperature change characteristic may mean a temperature decrease amount per unit time, that is, a temperature decrease rate in an electrically heated catalyst. Alternatively, the temperature change characteristic may mean a time interval required for the temperature of the electrically heated catalyst to decrease by a predetermined temperature.

  According to the research on the temperature change characteristic by the present inventors, the temperature change characteristic in the electrically heated catalyst, typically, the time required to decrease by a predetermined temperature is, for example, a conventional ternary such as cordierite. It has been found that the time required for the catalyst to decrease by a predetermined temperature is short. This is because the electrically heated catalyst includes a group of elements having a high thermal conductivity such as SiC (ie, silicon carbide), and the content ratio thereof is compared with that of a conventional three-way catalyst such as kojleite. This is because there are many. As a result, the temperature decrease rate, which is an example of the temperature change characteristic of the electrically heated catalyst, is compared with the temperature decrease rate of a conventional three-way catalyst such as cordierite due to the difference in the degree of thermal conductivity. large. In particular, it has been found that the difference between the temperature decrease rate of an electrically heated catalyst and the temperature decrease rate of a conventional three-way catalyst such as Kojjirite increases as the catalyst temperature increases.

  Thus, in the present invention, the temperature of the electrically heated catalyst is adjusted so as to approach the second target temperature determined in accordance with the temperature decrease rate of the electrically heated catalyst in addition to the temperature of the downstream catalyst. Controls the amount of current applied to the catalyst. That is, in the present invention, the temperature of the electrically heated catalyst is set close to the second target temperature that is higher than the above-described first target temperature by an amount corresponding to the rate of temperature decrease of the electrically heated catalyst. Controls the amount of current applied to the catalyst. Thereby, the electricity supply stop temperature used as the opportunity at the time of stopping the electricity supply process (namely, heat processing) of an electrically heated catalyst can be raised. As a result, after the actual temperature of the electrically heated catalyst reaches this higher energization stop temperature, it is possible to delay the timing when the temperature decreases with time and falls below the energization start temperature. Thereby, the frequency which performs the electricity supply process of an electrically heated catalyst can be decreased. Thereby, for example, the frequency of energizing the electrically heated catalyst from a secondary battery such as a battery can be reduced and the energization amount can be reduced, so that the consumption of the secondary battery can be effectively reduced. Thereby, it is possible to improve the energy efficiency of the whole hybrid vehicle including the fuel consumption of the internal combustion engine and the electric energy of the secondary battery. In particular, in a plug-in HV vehicle having a low opportunity and frequency of starting an internal combustion engine, it is very preferable in practice to improve energy efficiency and reliability. In addition, since the torque fluctuation generated in the internal combustion engine can be reduced by reducing the opportunity and frequency of starting the internal combustion engine, drivability in the hybrid vehicle can be improved.

  According to one aspect of the second exhaust gas purification apparatus for a hybrid vehicle of the present invention, when the temperature of the electric heating catalyst falls below a heating start temperature lower than the second target temperature, the electricity supply amount control means Energization of the heating catalyst is started, and when the temperature of the electric heating catalyst exceeds a heating stop temperature higher than the second target temperature, the electric heating catalyst is stopped so as to stop energization of the electric heating catalyst. Control the energization amount.

  According to this aspect, the control of the energization amount of the electrically heated catalyst is more accurately executed by comparing the heating start temperature and the heating stop temperature determined according to the second target temperature with the temperature of the electrically heated catalyst. Is possible. As a result, it is possible to bring the temperature of the electrically heated catalyst closer to the second target temperature with higher accuracy.

  Another aspect of the second exhaust gas purification apparatus for a hybrid vehicle of the present invention is an internal combustion engine mounted on the vehicle, ignition means for igniting fuel of the internal combustion engine, an electric motor mounted on the vehicle, and the electric motor And at least one of fuel efficiency and thermal efficiency at an optimal ignition timing before shifting from running by the internal combustion engine to running by the electric motor. And control means for controlling the ignition means so as to ignite the fuel at a timing delayed from a certain reference time.

  According to this aspect, before actually switching from traveling by an internal combustion engine (so-called HV traveling) to traveling by an electric motor (so-called EV traveling), the fuel is ignited at a timing retarded from the reference timing, thereby The temperature of gas can be made higher. As a result, the temperature of the downstream catalyst can be further increased by the thermal energy of the exhaust gas itself having a higher temperature. In particular, in the hybrid vehicle, the heat treatment of the downstream catalyst by the exhaust gas is performed when the hybrid vehicle is running on HV, that is, when the internal combustion engine is operating. Thus, it is very useful in practice that the temperature of the downstream catalyst can be further increased before actually switching from HV traveling to EV traveling without operating the internal combustion engine.

  Thus, according to this aspect, the temperature of the downstream catalyst can be further increased, and accordingly, the second target temperature can be decreased. Typically, the energization start temperature that triggers the start of energization processing of the electrically heated catalyst can be reduced. As a result, the timing at which the actual temperature of the electrically heated catalyst falls below the energization start temperature can be delayed, and thus the frequency of performing the electrically energized process of the electrically heated catalyst can be reduced. Thereby, for example, the frequency of energizing the EHC 206 from a secondary battery such as a battery can be reduced and the energization amount can be reduced, so that the consumption of the secondary battery can be effectively reduced. Thereby, it is possible to improve the energy efficiency of the whole hybrid vehicle including the fuel consumption of the internal combustion engine and the electric energy of the secondary battery. In particular, in a plug-in HV vehicle having a low opportunity and frequency of starting an internal combustion engine, it is very preferable in practice to improve energy efficiency and reliability.

  In addition, by performing the ignition timing retard control described above, torque fluctuations generated in the internal combustion engine can be reduced, so that drivability in a hybrid vehicle can be improved.

  In another aspect of the second exhaust gas purification apparatus for a hybrid vehicle of the present invention, the control means retards the reference timing when the temperature of the electric heating catalyst and the downstream catalyst does not exceed a predetermined threshold. The ignition means is controlled to ignite the fuel at a predetermined timing, and when the temperature of at least one of the electrically heated catalyst and the downstream catalyst exceeds the predetermined threshold, the fuel is ignited at the reference timing The ignition means is controlled as follows.

  According to this aspect, when the temperature of at least one of the electrically heated catalyst and the downstream catalyst exceeds the predetermined threshold value, the fuel is ignited at the reference timing by the ignition means under the control of the control means. Here, the predetermined threshold value according to the present invention is typically a temperature exceeding the activation temperature of the electrically heated catalyst, and the thermal energy of the electrically heated catalyst is transferred through the flow of the exhaust gas. It may mean a temperature at which activation of the downstream catalyst can be promoted by being transmitted to the downstream catalyst.

  As a result, when the purification effect is sufficient and it is not necessary to implement the retard control, the implementation of the retard control can be omitted, so that it is possible to shift to EV traveling more quickly.

  In order to solve the above problems, an exhaust gas purification method for a hybrid vehicle according to the present invention includes an electrically heated catalyst heated by energization, and a downstream catalyst provided downstream of the electrically heated catalyst. A method for purifying exhaust gas of a hybrid vehicle, comprising: a downstream catalyst temperature specifying step for specifying a temperature of the downstream catalyst; and a temperature of the electric heating catalyst at the start of the internal combustion engine is determined by the specified downstream catalyst temperature. And an energization amount control step for controlling the energization amount of the electrically heated catalyst so as to approach the first target temperature determined according to.

  According to the exhaust gas purification method for a hybrid vehicle according to the present invention, it is possible to receive various benefits of the above-described exhaust gas purification apparatus for a hybrid vehicle according to the present invention.

  Incidentally, the exhaust purification method for a hybrid vehicle according to the present invention can also adopt various aspects in response to the various aspects of the above-described exhaust purification apparatus for a hybrid vehicle according to the present invention.

  In order to solve the above-described problem, a second exhaust gas purification method for a hybrid vehicle according to the present invention includes an electrically heated catalyst heated by energization, and a downstream catalyst provided downstream of the electrically heated catalyst. An exhaust gas purification method for a hybrid vehicle comprising: a downstream catalyst temperature specifying step for specifying a temperature of the downstream catalyst; and the specified downstream catalyst temperature and temperature change characteristics of the electrically heated catalyst (typically Specifically, the temperature of the electrically heated catalyst approaches the second target temperature determined in accordance with the degree of temperature decrease with time, more typically the temperature decreasing per unit time). An energization amount control step for controlling the energization amount of the electrically heated catalyst.

  According to the second exhaust gas purification method for a hybrid vehicle according to the present invention, it is possible to receive various benefits of the above-described second exhaust gas purification apparatus for a hybrid vehicle according to the present invention.

  Incidentally, the second exhaust gas purification method for a hybrid vehicle according to the present invention can also adopt various aspects in response to the various aspects of the second exhaust gas purification apparatus for a hybrid vehicle according to the present invention described above.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

1 is a schematic configuration diagram conceptually showing the configuration of an exhaust emission control device for a hybrid vehicle according to a first embodiment of the present invention. 3 is a flowchart showing a flow of control processing at the time of engine start in a control unit that performs overall control of the exhaust gas purification apparatus for a hybrid vehicle according to the first embodiment of the present invention. 5 is a map showing a quantitative and qualitative relationship between the first target temperature of the catalytic converter 204 and the temperature of the downstream catalyst 205 according to the first embodiment of the present invention. It is the flowchart which showed the flow of the control processing at the time of engine starting in the control unit which performs overall control of the exhaust gas purification apparatus of the hybrid vehicle which concerns on 2nd Embodiment of this invention. It is the flowchart which showed the flow of the control processing at the time of engine starting in the control unit which performs overall control of the exhaust gas purification apparatus of the hybrid vehicle which concerns on 3rd Embodiment of this invention. It is the map which showed the quantitative and qualitative relationship between the 1st target temperature of the catalytic converter 204 which concerns on 3rd Embodiment of this invention, and an engine stop counter. It is the flowchart which showed the flow of the control processing in the control unit which performs overall control of the hybrid vehicle containing the exhaust gas purification device which concerns on 4th Embodiment of this invention. The first target temperature of the catalytic converter 204 according to the fourth embodiment of the present invention, the heating start temperature that is the temperature of the catalytic converter 204 when starting the heating process of the catalytic converter 204, and the heating process of the catalytic converter 204 are stopped. 6 is a map showing a quantitative and qualitative relationship between a heating stop temperature that is the temperature of the catalytic converter 204 and the temperature of the downstream catalyst 205 at the time. It is the flowchart which showed the flow of the control processing in the control unit which performs overall control of the hybrid vehicle containing the exhaust gas purification device which concerns on 5th Embodiment of this invention. The second target temperature of the catalytic converter 204 according to the fifth embodiment of the present invention, the heating start temperature which is the temperature of the catalytic converter 204 when starting the heating process of the catalytic converter 204, and the heating process of the catalytic converter 204 are stopped. 6 is a map showing a quantitative and qualitative relationship between a heating stop temperature that is the temperature of the catalytic converter 204 and the temperature of the downstream catalyst 205 at the time. It is the graph which showed the time required for the catalytic converter 204 which concerns on 5th Embodiment of this invention, and the conventional three-way catalyst to fall to each temperature from the catalyst temperature of 600 degreeC. FIG. 12A is a graph showing a quantitative and qualitative relationship between the temperature of the downstream catalyst 205 and the target temperature of the catalytic converter 204 according to the fifth embodiment of the present invention, and the temperature of the catalytic converter 204 and the catalytic converter. A graph showing a quantitative and qualitative relationship with the temperature decrease rate of 204 (FIG. 12B), and a quantitative and qualitative relationship between the temperature of the downstream catalyst 205 and the second target temperature of the catalytic converter 204 It is the graph (FIG.12 (c)) which showed the relationship. It is the flowchart which showed the flow of the control processing in the control unit which performs overall control of the hybrid vehicle containing the exhaust gas purification device which concerns on 6th Embodiment of this invention.

  Various preferred embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
(Basic configuration)
First, a basic configuration of a hybrid vehicle equipped with an exhaust emission control device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a basic configuration diagram showing a schematic configuration of a hybrid vehicle incorporating the exhaust emission control device according to the first embodiment. The hybrid vehicle mainly includes a power system that generates a driving force, a control system thereof, a power transmission system that transmits the driving force from the driving source to the driving wheels 116 and 118, a driving operation unit, and the like. Yes. The power system includes a system including the engine 150 and a system including the motors MG1 and MG2, and the control system is an electronic control unit (hereinafter referred to as EFIECU) for mainly controlling the operation of the engine 150. ) 170, a control unit 190 that mainly controls the operation of the motors MG1 and MG2, and various sensor units that detect and input / output signals necessary for the EFIECU 170 and the control unit 190. Although the internal configurations of the EFIECU 170 and the control unit 190 are not shown, these are one-chip microcomputers each having a CPU, ROM, RAM, etc., and the CPU follows the program recorded in the ROM according to the following program. Various control processes shown in FIG. In this embodiment, the control system corresponds to the operation control device.

  The engine 150 sucks the air-fuel mixture of the air sucked from the suction port 200 and the gasoline injected from the fuel injection valve 151 into the combustion chamber 152, and moves the movement of the piston 154 pushed down by the explosion of the air-fuel mixture to the crankshaft 156. Convert to rotational motion. This explosion occurs when the air-fuel mixture is ignited and burned by the electric spark formed by the spark plug 162 by the high voltage guided from the igniter 158 via the distributor 160. Exhaust generated by the combustion passes through the exhaust port 202 and is discharged into the atmosphere through an exhaust system including the catalytic converter 204, the sub muffler 208 and the main muffler 210. The catalytic converter 204 is typically an electrically heated catalyst that purifies exhaust gas by heating the catalyst itself with electric energy using an electric heater or the like. That is, the catalytic converter 204 cannot sufficiently purify the exhaust gas unless the catalyst reaches the activation temperature (in this embodiment, around 400 degrees Celsius). A catalyst heater 206 is provided. Alternatively, the catalytic converter 204 is typically a filter such as a DPF (Diesel Particulate Filter) configured by a conductive base material such as SiC (silicon carbide) and configured to generate heat according to an applied voltage. It may be a device. Alternatively, the catalytic converter 204 is typically capable of purifying HC, CO, PM (Particulate Matter) or the like with oxidation combustion by plasma discharge, for example, plasma discharge such as a plasma reactor. It may be a purification device or the like.

  In particular, this electrically heated catalytic converter 204 has a higher thermal conductivity than a three-way catalyst such as kojjirite. This is because the electrically heated catalytic converter 204 includes a group of elements having a high thermal conductivity such as SiC (ie, silicon carbide), and the content ratio thereof is, for example, a conventional ternary such as cordierite. This is because it is more than the catalyst.

  Further, the catalytic converter 205 (hereinafter referred to as “downstream catalyst 205” as appropriate) is provided on the downstream side of the catalytic converter 204 (that is, the side toward the atmosphere when discharged), and is included in the exhaust of the internal combustion engine. This is an apparatus for subjecting so-called emissions of harmful components such as HC, CO and NOx to redox treatment using a three-way catalyst. The control unit 190 exemplifies a specific example of the energization amount control means according to the present invention. Further, the catalytic converter 204 exemplifies a catalyst portion that is one element constituting the electrically heated catalyst according to the present invention. Heating means for heating the catalyst portion by converting supplied electric energy into heat energy, which is another element constituting the electrically heated catalyst according to the present invention, by an electrocatalyst heater (so-called EHC) 206. Illustrated. The catalytic converter 205 constitutes an example of the downstream catalyst according to the present invention.

  The operation of engine 150 is controlled by EFIECU 170. The engine 150 control performed by the EFIECU 170 includes ignition timing control of the spark plug 162 according to the rotational speed of the engine 150, fuel injection amount control according to the intake air amount, and the like. In order to control the engine 150, the EFIECU 170 is connected to various sensors that indicate the operating state of the engine 150. For example, a rotational speed sensor 176 and a rotational angle sensor 178 provided in the distributor 160 for detecting the rotational speed and rotational angle of the crankshaft 156. In addition, for example, a starter switch 179 for detecting the ignition key state ST is connected to the EFIECU 170, but other sensors, switches, and the like are not shown.

  Control of the engine 150 by the EFIECU 170 includes control of driving efficiency. The engine 150 can be operated at various torques and rotational speeds.

  The motor MG1 is configured as a synchronous motor generator, and includes a rotor 132 having a plurality of permanent magnets on the outer peripheral surface, and a stator 133 around which a three-phase coil that forms a rotating magnetic field is wound. The stator 133 is formed by laminating thin plates of non-oriented electrical steel plates, and is fixed to the case 119. The motor MG1 operates as an electric motor that rotationally drives the rotor 132 by an interaction between a magnetic field generated by a permanent magnet provided in the rotor 132 and a magnetic field formed by a three-phase coil provided in the stator 133. It operates also as a generator which produces electromotive force in the both ends of the three-phase coil with which the stator 133 was equipped by interaction of these.

  Similarly to the motor MG1, the motor MG2 is configured as a synchronous motor generator, and includes a rotor 142 having a plurality of permanent magnets on the outer peripheral surface, and a stator 143 wound with a three-phase coil that forms a rotating magnetic field. The stator 143 of the motor MG2 is also formed by laminating thin plates of non-oriented electrical steel sheets, and is fixed to the case 119. This motor MG2 also operates as an electric motor or a generator like the motor MG1.

  These motors MG1 and MG2 are electrically connected to the battery 194 and the control unit 190 via a transistor inverter 193 incorporating a plurality of transistors for switching. In addition, the EHC 206 and various sensors are electrically connected to the control unit 190. The sensors connected to the control unit 190 include an accelerator pedal position sensor 164a, a brake pedal position sensor 165a, a shift position sensor 184, a remaining capacity detector 199 of the battery 194, and a catalyst temperature sensor 204a that measures the temperature of the catalytic converter 204. There is a catalyst temperature sensor 205 a for measuring the temperature of the catalytic converter 205. The catalyst temperature sensor 205a constitutes an example of a downstream catalyst temperature specifying unit according to the present invention.

  A method for controlling the motors MG1 and MG2 using the transistor inverter 193 is a well-known technique. That is, a control signal is output from the control unit 190 to the transistor inverter 193 to switch each transistor incorporated in the transistor inverter 193, and the current flowing in the three-phase coils of the motors MG1 and MG2 is pseudo-sine wave by PWM control. Then, a rotating magnetic field is formed in each of the three-phase coil provided in the stator 133 of the motor MG1 and the three-phase coil provided in the stator 143 of the motor MG2. In order to enable the control of the driving state of the hybrid vehicle including the control of the motors MG1 and MG2 and the energization control to the EHC 206 described above, the control unit 190 includes various signals from the driving operation unit, The catalyst temperature, the catalyst temperature in the catalytic converter 204, the remaining capacity of the battery 194, and the like are input, and various information is exchanged with the EFIECU 170 that controls the engine 150 by communication. Specifically, as various signals from the driving operation unit, the accelerator pedal position (accelerator pedal depression amount) AP from the accelerator pedal position sensor 164a and the brake pedal position (brake pedal depression amount) from the brake pedal position sensor 165a are included. There is a shift position SP from BP and shift position sensor 184. Further, the catalyst temperature in the catalytic converter 205 is detected by a catalyst temperature sensor 205a. The catalyst temperature in the catalytic converter 204 is detected by a catalyst temperature sensor 204a. As a result, as will be described later, the control unit 190 causes the EHC 206 for bringing the actually detected catalyst temperature in the catalytic converter 204 close to the first target temperature determined in accordance with the catalyst temperature in the catalytic converter 205. The energization control can be performed. Further, the remaining capacity of the battery 194 is detected by a remaining capacity detector 199. The remaining capacity detector 199 detects the remaining capacity by measuring the specific gravity of the electrolyte of the battery 194 or the entire weight of the battery 194, or calculates the remaining capacity by calculating the current value and time of charging / discharging. There are known ones that detect the remaining capacity by instantaneously shorting the terminals of the battery and passing the current to measure the internal resistance.

  The power transmission system for transmitting the driving force from the driving source to the driving wheels 116 and 118 is a rotation for transmitting the rotation of the motor MG1 and the motor MG2 to the crankshaft 156 and the planetary carrier shaft 127 for transmitting the power of the engine 150. The shafts 125 and 126 are mechanically coupled to a power transmission gear 111 via a planetary gear 120 described later. The power transmission gear 111 is finally coupled to left and right drive wheels 116 and 118 via a differential gear 114. It is the composition which becomes.

  The combination of the planetary gear 120 and the crankshaft 156, the planetary carrier shaft 127, the rotating shaft 125 of the motor MG1, and the rotating shaft 126 of the MG2 are well-known techniques.

  A power take-off gear 128 for taking out power is coupled to the ring gear 122 on the motor MG1 side. The power take-out gear 128 is connected to the power transmission gear 111 by a chain belt 129, and power is transmitted between the power take-out gear 128 and the power transmission gear 111. Based on the above-described configuration and the nature of planetary gear 120, the hybrid vehicle can run using only motor MG2 as a drive source, or can run using both engine 150 and motor MG2 as drive sources. When traveling using both engine 150 and motor MG2 as drive sources, engine 150 can be operated at an efficient operating point in accordance with the required torque and the torque that can be generated by motor MG2, so only engine 150 is driven. It is superior in resource saving and exhaust purification compared to the source vehicle. Based on such a function, the hybrid vehicle normally travels only with the motor MG2, and when the remaining capacity of the battery 194 is reduced and it is expected that the travel will be obstructed, or during acceleration The drive source is properly used in the form of starting the engine 150 when more power is required, such as during climbing or climbing. On the other hand, since the rotation of the crankshaft 156 can be transmitted to the motor MG1 via the planetary carrier shaft 127 and the sun gear shaft 125, it is possible to travel while generating power with the motor MG1 by the operation of the engine 150.

(Operating principle)
Next, the operation principle of the exhaust gas purification system for a hybrid vehicle according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing a flow of control processing at the time of engine start in the control unit that performs overall control of the hybrid vehicle including the exhaust emission control apparatus according to the first embodiment of the present invention. FIG. 3 is a map showing a quantitative and qualitative relationship between the first target temperature of the catalytic converter 204 and the temperature of the downstream catalyst 205 according to the first embodiment of the present invention. The control process shown in FIG. 2 is repeatedly executed by the control unit 190 at a predetermined cycle.

  As shown in FIG. 2, it is first determined whether or not to start the engine under the control of the control unit 190 (step S101). Here, when it is determined that the engine starts to be started (step S101: Yes), it is determined whether or not the heat treatment of the catalytic converter 204 by the electrocatalyst heater is necessary under the control of the control unit 190 ( Step S102). Typically, it may be determined whether or not the catalyst temperature of the catalytic converter 204 exceeds a predetermined temperature that is a catalyst activation temperature.

  As a result of the determination in step S102, when it is determined that the heat treatment of the catalytic converter 204 is necessary (step S102: Yes), a quantitative value indicating the temperature of the downstream catalyst 205 being measured under the control of the control unit 190. Target or qualitative information is stored and acquired in a storage device such as a ROM (step S103).

  Next, under the control of the control unit 190, based on the first predetermined map, the first target temperature that is the target of the catalytic converter 204 corresponding to the acquired temperature of the downstream catalyst 205 is determined (step S104). ). Here, the first predetermined map according to the present embodiment is typically a state in which the total or total amount of the degree of purification of the catalytic converter 204 and the degree of purification of the downstream catalyst 205 exceeds a predetermined level. It means a map showing a quantitative and qualitative relationship between the temperature of the downstream catalyst 205 and the first target temperature of the catalytic converter 204.

  Typically, as shown in FIG. 3, as the temperature of the downstream catalyst 205 increases, the first target temperature of the catalytic converter 204 is set lower. Thus, as the temperature of the downstream catalyst 205 becomes higher, the first target temperature of the catalytic converter 204 is lowered, and the capacity of the catalytic converter 204 out of the total capacity of the catalyst capacity indicating the degree of purification capacity of the catalyst in the exhaust purification system. By further reducing the ratio, it is possible to reduce the amount of power supplied from the secondary battery such as a battery to the EHC 206 and reduce the consumption of the secondary battery. In addition, the thermal energy of the catalytic converter 204 is effectively prevented from being excessively transmitted to the downstream catalyst 205 through the exhaust gas flow, and the temperature of the downstream catalyst 205 is effectively increased excessively. It is possible to reduce it.

  On the other hand, as shown in FIG. 3, as the temperature of the downstream catalyst 205 becomes lower, the first target temperature of the catalytic converter 204 is set higher. Thus, as the temperature of the downstream catalyst 205 becomes lower, the first target temperature of the catalytic converter 204 is made higher, and the proportion of the catalyst capacity of the catalytic converter 204 in the total amount of catalyst capacity is further increased, so that the downstream catalyst 205 is increased. It is possible to compensate for the decrease or shortage of the catalyst capacity and to effectively improve the purification efficiency in the exhaust purification system. In addition, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the thermal energy of the catalytic converter 204 is increased in a larger amount through the flow of the exhaust gas. By transmitting to the downstream catalyst 205, the activation of the downstream catalyst 205 can be promoted, and the purification efficiency in the exhaust purification system can be effectively improved.

  Next, under the control of the control unit 190, an energization amount for energizing the EHC 206 that heats the catalytic converter 204 is calculated according to the determined first target temperature of the catalytic converter 204 (step S105). Specifically, the thermal energy necessary for the current temperature of the catalytic converter 204 to reach the first target temperature of the catalytic converter 204 is calculated, and the energization amount of the EHC 206 corresponding to the calculated thermal energy is calculated. .

  Next, the EHC 206 is energized by the calculated energization amount under the control of the control unit 190 (step S106).

  Next, under the control of the control unit 190, for example, after energization to the EHC 206 is completed, the engine is started (step S107).

  As a result, according to the present embodiment, even when the temperature of the downstream catalyst 205 is low, the catalytic converter 204 can supplement the catalyst capacity of the downstream catalyst 205 as described above. In addition, it is possible to more effectively purify the exhaust gas when starting the engine in a hybrid vehicle that has a low chance and frequency of starting the engine and the temperature of the downstream catalyst 205 tends to decrease. Thus, the catalytic converter 204 and the downstream catalyst 205 are coordinated by changing the first target temperature of the catalytic converter 204 and changing the degree of activation of the downstream catalyst 205 in accordance with the temperature of the downstream catalyst 205. In addition, it is possible to achieve both the efficient and optimal power control of the EHC 206 and the improvement of the exhaust gas purification efficiency by acting organically.

  In general, in an exhaust purification device (or an exhaust emission system) including an electrically heated catalyst provided with the above-described catalytic converter 204 and EHC 206, the catalytic converter 204 can be warmed up by supplying electric power. It is difficult to warm up the downstream catalyst 205 located downstream of the converter 204. In particular, in a plug-in hybrid vehicle (that is, a plug-in HV vehicle) in which the opportunity to start the engine is not uniformly determined, the opportunity to start the engine is determined according to, for example, the required amount of engine load and the state of charge. Is done. For this reason, it becomes technically difficult to sufficiently purify the exhaust gas of the engine by effectively using the downstream catalyst 205. Specifically, after the engine is started, the thermal energy of the exhaust gas itself is transmitted to the downstream catalyst 205, and the thermal energy of the catalytic converter 204 is transmitted through the flow of the exhaust gas. However, in a vehicle with a low opportunity and frequency of starting an engine such as a plug-in HV vehicle, the downstream catalyst 205 cools during a period when the engine is not started, and the downstream catalyst 205 is sufficiently and quickly activated when the engine is started. It becomes technically difficult to warm up. Specifically, the total amount of the catalyst capacity in the exhaust purification system, that is, the sum of the capacity of the catalytic converter 204 and the capacity of the downstream catalyst 205 is the exhaust when the engine mounted on the hybrid vehicle is operated at a high load. It is determined according to the amount of gas. For this reason, even if the catalytic converter 204 is warmed up, if the downstream catalyst 205 is not warmed up, it becomes technically difficult to sufficiently purify the exhaust gas.

(Second Embodiment)
(Operating principle)
Next, with reference to FIG. 4, the operation principle of the exhaust gas purification apparatus for a hybrid vehicle according to the second embodiment of the present invention will be described. FIG. 4 is a flowchart showing the flow of control processing at the time of engine start in the control unit 190 that performs overall control of the exhaust gas purification apparatus for a hybrid vehicle according to the second embodiment of the present invention. The control process shown in FIG. 4 is repeatedly executed by the control unit 190 at a predetermined cycle.

  As shown in FIG. 4, after the above-described steps S101 and S102, under the control of the control unit 190, for example, a period from 30 minutes before to the present, for example, after a predetermined time from the present, It is determined whether there is an activation history (step S201). Here, the predetermined time according to the second embodiment may typically mean a time taken from when the engine is started to when the catalyst temperature of the catalytic converter 204 falls below the activation temperature after the engine is stopped.

  As a result of the determination in step S201, when it is determined that there is an engine activation history after a predetermined time from the present time (step S201: Yes), the target of the catalytic converter 204 is controlled under the control of the control unit 190. The temperature T1 is determined as the first target temperature (step S202). Here, the temperature T1 is typically the first target temperature of the catalytic converter 204 on the first predetermined map described above, and may be determined according to the predetermined time described above.

  Thus, when there is an engine start history after a predetermined time from the present time, it is estimated that the engine stop time is short and the temperature of the downstream catalyst 205 is high. Is set low. Thereby, when it is estimated that the temperature of the downstream catalyst 205 is high, by lowering the first target temperature of the catalytic converter 204 and reducing the ratio of the capacity of the catalytic converter 204 out of the total amount of catalyst capacity, for example, It is possible to reduce the energization amount from the secondary battery such as a battery to the EHC 206 and reduce the consumption of the secondary battery. In addition, the thermal energy of the catalytic converter 204 is effectively prevented from being excessively transmitted to the downstream catalyst 205 through the exhaust gas flow, and the temperature of the downstream catalyst 205 is effectively increased excessively. It is possible to reduce it.

  On the other hand, as a result of the determination in step S201, if it is not determined that there is an engine activation history after a predetermined time from the present time (step S201: No), the target of the catalytic converter 204 is controlled under the control of the control unit 190. As the first target temperature, temperature T2 (where T1 <T2) is determined (step S203). Here, the temperature T2 is typically the first target temperature of the catalytic converter 204 on the first predetermined map described above, and may be determined to be higher than the temperature T1 described above.

  Thus, if there is no engine start history after a predetermined time from the present time, it is estimated that the engine stop time is long and the temperature of the downstream catalyst 205 is low. One target temperature is set high. Thereby, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the ratio of the catalyst capacity of the catalytic converter 204 in the total amount of the catalyst capacity is further increased. It is possible to compensate for a decrease in the catalyst capacity of the catalyst 205 and to effectively improve the purification efficiency in the exhaust purification system. In addition, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the thermal energy of the catalytic converter 204 is increased in a larger amount through the flow of the exhaust gas. By transmitting to the downstream catalyst 205, the activation of the downstream catalyst 205 can be promoted, and the purification efficiency in the exhaust purification system can be effectively improved.

  Thereafter, steps S105 to S107 described above are performed under the control of the control unit 190.

  In particular, according to the second embodiment, the first target temperature of the catalytic converter 204 can be determined easily and quickly depending on whether or not there is an engine startup history.

(Third embodiment)
(Operating principle)
Next, with reference to FIGS. 5 and 6, the operation principle of the exhaust emission control device for a hybrid vehicle according to the third embodiment of the present invention will be described. FIG. 5 is a flowchart showing the flow of control processing at the time of engine start in the control unit 190 that performs overall control of the exhaust gas purification apparatus for a hybrid vehicle according to the third embodiment of the present invention. FIG. 6 is a map showing a quantitative and qualitative relationship between the first target temperature of the catalytic converter 204 and the engine stop counter according to the third embodiment of the present invention. The control process shown in FIG. 5 is repeatedly executed by the control unit 190 at a predetermined cycle.

  As shown in FIG. 5, it is determined whether or not the engine is being started under the control of the control unit 190 through steps S101 and S102 described above (step S301). Here, when it is determined that the engine is being started (step S301: Yes), an engine stop counter variable indicating the length of the engine stop time is input to zero (step S302). On the other hand, as a result of the determination in step S301, when it is not determined that the engine is being started (step S301: No), an engine stop counter variable indicating the length of the engine stop time is incremented by 1 (step S303). ).

  Next, under the control of the control unit 190, based on the second predetermined map, the first target temperature that is the target of the catalytic converter 204 corresponding to the engine stop counter variable is determined (step S304). Here, the second predetermined map according to the present embodiment is typically a state in which the total or total amount of the degree of purification of the catalytic converter 204 and the degree of purification of the downstream catalyst 205 exceeds a predetermined level. It means a map showing a quantitative and qualitative relationship between the engine stop counter variable and the first target temperature of the catalytic converter 204. Typically, as shown in FIG. 6, as the engine stop counter variable increases, in other words, as the engine stop time increases, the first target temperature of catalytic converter 204 is set higher.

  Thus, as the engine stop counter variable increases, it is estimated that the engine stop time is longer and the temperature of the downstream catalyst 205 is lower, so the first target temperature of the catalytic converter 204 is set higher. Thereby, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the ratio of the catalyst capacity of the catalytic converter 204 in the total amount of the catalyst capacity is further increased. It is possible to compensate for a decrease in the catalyst capacity of the catalyst 205 and to effectively improve the purification efficiency in the exhaust purification system. In addition, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the thermal energy of the catalytic converter 204 is increased in a larger amount through the flow of the exhaust gas. By transmitting to the downstream catalyst 205, the activation of the downstream catalyst 205 can be promoted, and the purification efficiency in the exhaust purification system can be effectively improved.

  On the other hand, as shown in FIG. 6, the first target temperature of catalytic converter 204 is set lower as the engine stop counter variable becomes smaller, in other words, as the engine stop time becomes shorter. Thus, when the engine stop counter variable is small and the engine stop time is short, it is estimated that the temperature of the downstream catalyst 205 is high, so the first target temperature of the catalytic converter 204 is set low. Thereby, when it is estimated that the temperature of the downstream catalyst 205 is high, by lowering the first target temperature of the catalytic converter 204 and reducing the ratio of the capacity of the catalytic converter 204 out of the total amount of catalyst capacity, for example, It is possible to reduce the energization amount from the secondary battery such as a battery to the EHC 206 and reduce the consumption of the secondary battery. In addition, the thermal energy of the catalytic converter 204 is effectively prevented from being excessively transmitted to the downstream catalyst 205 through the exhaust gas flow, and the temperature of the downstream catalyst 205 is effectively increased excessively. It is possible to reduce it.

  Thereafter, steps S105 to S107 described above are performed under the control of the control unit 190.

  In particular, according to the third embodiment, the first target temperature of the catalytic converter 204 can be easily and quickly determined by the engine stop counter variable indicating the length of the engine stop time.

(Fourth embodiment)
(Operating principle)
Next, with reference to FIG.7 and FIG.8, the principle of operation of the exhaust gas purification system of the hybrid vehicle which concerns on 4th Embodiment of this invention is demonstrated. FIG. 7 is a flowchart showing the flow of control processing in the control unit that performs overall control of the hybrid vehicle including the exhaust emission control apparatus according to the fourth embodiment of the present invention. FIG. 8 shows the first target temperature of the catalytic converter 204 according to the fourth embodiment of the present invention, the heating start temperature that is the temperature of the catalytic converter 204 when the heating process of the catalytic converter 204 is started, 7 is a map showing a quantitative and qualitative relationship between a heating stop temperature, which is a temperature of the catalytic converter 204 when stopping the heat treatment, and a temperature of the downstream catalyst 205. The control process shown in FIG. 7 is repeatedly executed by the control unit 190 at a predetermined cycle.

  As shown in FIG. 7, first, under the control of the control unit 190, quantitative or qualitative information indicating the remaining capacity of the battery 194, that is, a so-called battery state (ie, SOC (State of Charge)) is acquired. (Step S401).

  Next, it is determined whether or not the acquired SOC exceeds 30% under the control of the control unit 190 (step S402). Here, when it is determined that the obtained SOC exceeds 30% (step S402: Yes), the catalytic converter 204 in which the heating process by the electrocatalyst heater is executed under the control of the control unit 190 is measured. Quantitative or qualitative information indicating the catalyst temperature is stored and acquired as a variable Tsic in a storage device such as a ROM (step S403).

  Next, under the control of the control unit 190, quantitative or qualitative information indicating the measured temperature of the downstream catalyst 205 is stored and acquired as a variable Tufc in a storage device such as a ROM (step S404).

  Next, under the control of the control unit 190, the variable ksic1 indicating the heating start temperature, which is the temperature of the catalytic converter 204 when starting the heat treatment of the catalytic converter 204 by the electrocatalyst heater, and the catalyst by the electrocatalyst heater A variable ksic2 indicating the heating stop temperature, which is the temperature of the catalytic converter 204 when the heating process of the converter 204 is stopped, is acquired (step S405). Specifically, the variable ksic1 indicating the heating start temperature and the variable ksic2 indicating the heating stop temperature are uniquely determined according to the variable Tufc indicating the temperature of the downstream catalyst 205. Specifically, as shown in FIG. 8, when the temperature of the downstream catalyst 205 indicated by the variable Tufc is the temperature T0, the heating start temperature T1 indicated by the variable ksic1 and the heating stop temperature T2 indicated by the variable ksic2 are It is determined uniquely.

  In this way, as shown by the solid line in FIG. 8, the temperature of the catalytic converter 204 according to the fourth embodiment is brought close to the first target temperature that can be determined according to the heating start temperature and the heating stop temperature. In addition, as described above, the heating start temperature and the heating stop temperature are uniquely determined according to the temperature of the downstream catalyst 205. As described above, the temperature of the catalytic converter 204 according to the fourth embodiment can appropriately approach the first target temperature that is uniquely determined according to the temperature of the downstream catalyst 205.

  Note that the method of comparing the temperature of the catalytic converter 204 with the heating start temperature and the heating stop temperature when the temperature of the catalytic converter 204 is brought close to the first target temperature is used in the first to third embodiments described above. Good. In addition, this method may be used in a fifth embodiment to be described later.

  Typically, as shown in FIG. 8, as the temperature of the downstream catalyst 205 increases, the first target temperature of the catalytic converter 204 is set lower. In this way, as the temperature of the downstream catalyst 205 increases, the first target temperature, the heating start temperature, and the heating stop temperature of the catalytic converter 204 are further lowered, and the ratio of the capacity of the catalytic converter 204 in the total amount of the catalyst capacity is further increased. By reducing, for example, it is possible to reduce the energization amount from the secondary battery such as a battery to the EHC 206 and reduce the consumption of the secondary battery. In addition, the thermal energy of the catalytic converter 204 is effectively prevented from being excessively transmitted to the downstream catalyst 205 through the exhaust gas flow, and the temperature of the downstream catalyst 205 is effectively increased excessively. It is possible to reduce it.

  On the other hand, as shown in FIG. 8, as the temperature of the downstream catalyst 205 becomes lower, the first target temperature of the catalytic converter 204 is set higher. Thus, as the temperature of the downstream catalyst 205 becomes lower, the first target temperature, the heating start temperature, and the heating stop temperature of the catalytic converter 204 are made higher, and the ratio of the catalyst capacity of the catalytic converter 204 in the total amount of catalyst capacity is set. By further increasing, it is possible to compensate for a decrease or shortage of the catalyst capacity of the downstream catalyst 205 and to effectively improve the purification efficiency in the exhaust purification system. In addition, when it is estimated that the temperature of the downstream catalyst 205 is low, the first target temperature of the catalytic converter 204 is made higher, and the thermal energy of the catalytic converter 204 is increased in a larger amount through the flow of the exhaust gas. By transmitting to the downstream catalyst 205, the activation of the downstream catalyst 205 can be promoted, and the purification efficiency in the exhaust purification system can be effectively improved.

  As a result, according to the fourth embodiment, even when the temperature of the downstream catalyst 205 is low, the catalytic converter 204 can supplement the catalyst capacity of the downstream catalyst 205 as described above. As described above, the exhaust gas can be more effectively purified when the engine is started in the hybrid vehicle in which the frequency and the frequency of starting the engine are low and the temperature of the downstream catalyst 205 is high. Thus, the catalytic converter 204 and the downstream catalyst 205 are coordinated by changing the first target temperature of the catalytic converter 204 and changing the degree of activation of the downstream catalyst 205 in accordance with the temperature of the downstream catalyst 205. In addition, it is possible to achieve both the efficient and optimal power control of the EHC 206 and the improvement of the exhaust gas purification efficiency by acting organically.

  In particular, according to the fourth embodiment, the heating start temperature, which is the temperature of the catalytic converter 204 when starting the heating process of the catalytic converter 204 by the electrocatalyst heater, and the heating process of the catalytic converter 204 by the electrocatalyst heater. The heating stop temperature, which is the temperature of the catalytic converter 204 when stopping the operation, is changed in accordance with the temperature of the downstream catalyst 205. As a result, the temperature of the catalytic converter 204 can be more accurately controlled by more accurately executing the heat treatment of the catalytic converter 204 using the heating start temperature and the heating stop temperature determined according to the temperature of the downstream catalyst 205 as a trigger. It is possible to approach the first target temperature.

  Next, it is determined whether or not the variable XENGON is “0”, that is, “zero” under the control of the control unit 190 (step S406). Here, when the variable XENGON is “0” (step S406: Yes), further, under the control of the control unit 190, the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is the heating start indicated by the variable ksic1. It is determined whether or not the temperature is lower (step S407). Here, when it is determined that the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is lower than the heating start temperature indicated by the variable ksic1 (step S407: Yes), the hybrid vehicle is controlled under the control of the control unit 190. Quantitative and qualitative information indicating the vehicle speed is stored and acquired as a variable spd in a storage device such as a ROM (step S408).

  Next, it is determined whether or not the variable spd is “0 (km / h)”, that is, whether or not the hybrid vehicle is stopped under the control of the control unit 190 (step S409). Here, when it is determined that the variable spd is “0 (km / h)” (step S409: Yes), “1” is substituted into the variable XSICON under the control of the control unit 190 (step S410). .

  Next, under the control of the control unit 190, the catalytic converter 204 performs a heating process using an electrocatalyst heater (step S411).

  On the other hand, when it is determined that the variable spd is not “0 (km / h)” as a result of the determination in step S409 described above, that is, when it is determined that the hybrid vehicle is not in the stopped state but in the traveling state (step). S409: No) Under the control of the control unit 190, “1” is substituted into the variable XENGON, and “0” is substituted into the variable XSICON (step S412).

  Next, under the control of the control unit 190, the engine 150 is brought into an operating state, and the catalytic converters 204 and 205 execute a heating process using the thermal energy of the exhaust gas discharged from the engine 150 (step S413).

  On the other hand, if the variable XENGON is not “0” as a result of the determination in step S406 described above, that is, if the variable XENGON is “1” (step S406: No), the variable Tsic is further controlled under the control of the control unit 190. It is determined whether or not the measured catalyst temperature of the catalytic converter 204 indicated by is smaller than the heating stop temperature indicated by the variable ksic2 (step S414). Here, when it is determined that the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is lower than the heating stop temperature indicated by the variable ksic2 (step S414: Yes), as described above under the control of the control unit 190. In addition, the engine 150 is put into an operating state, and the catalytic converters 204 and 205 execute the heating process using the thermal energy of the exhaust gas discharged from the engine 150 (step S413).

  On the other hand, as a result of the determination in step S414 described above, when it is determined that the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is not lower than the heating stop temperature indicated by the variable ksic2, that is, the measured value of the catalytic converter 204 is measured. When it is determined that the catalyst temperature is higher than the heating stop temperature indicated by the variable ksic2 (step S414: No), the operation of the engine 150 is stopped under the control of the control unit 190, and the catalyst converters 204 and 205 The heat treatment using the thermal energy of the exhaust gas discharged from 150 is stopped. In addition, under the control of the control unit 190, “0” is substituted into the variable XENGON (step S415).

  On the other hand, as a result of the determination in step S407 described above, when it is determined that the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is not lower than the heating start temperature indicated by the variable ksic1, that is, the catalytic converter indicated by the variable Tsic. If it is determined that the measured catalyst temperature of 204 is higher than the heating start temperature indicated by the variable ksic1 (step S407: No), whether or not the variable XSICON is “1” under the control of the control unit 190. Determination is made (step S416). If it is determined that the variable XSICON is “1” (step S416: Yes), whether or not the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is greater than the heating stop temperature indicated by the variable ksic2 Is determined (step S417). Here, when it is determined that the measured catalyst temperature of the catalytic converter 204 indicated by the variable Tsic is higher than the heating stop temperature indicated by the variable ksic2 (step S417: Yes), the catalytic converter 204 is controlled under the control of the control unit 190. , The heat treatment by the electrocatalyst heater is stopped. In addition, under the control of the control unit 190, “0” is substituted into the variable XSICON (step S418).

  On the other hand, if it is determined that the acquired SOC does not exceed 30% as a result of the determination in step S402 described above, that is, if it is determined that the acquired SOC does not exceed 30% (step S402: No), control is performed. Under the control of the unit 190, in the hybrid vehicle, the engine 150 is in an operating state, the battery 194 is charged, and the hybrid vehicle travels by the driving force output from the engine 150 (step S419).

(Fifth embodiment)
(Operating principle)
Next, the operation principle of the exhaust purification system for a hybrid vehicle according to the fifth embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a flowchart showing the flow of control processing in the control unit that performs overall control of the hybrid vehicle including the exhaust emission control apparatus according to the fifth embodiment of the present invention. The control process shown in FIG. 9 is repeatedly executed by the control unit 190 at a predetermined cycle. FIG. 10 shows the second target temperature of the catalytic converter 204 according to the fifth embodiment of the present invention, the heating start temperature that is the temperature of the catalytic converter 204 when the heating process of the catalytic converter 204 is started, 7 is a map showing a quantitative and qualitative relationship between a heating stop temperature, which is a temperature of the catalytic converter 204 when stopping the heat treatment, and a temperature of the downstream catalyst 205. FIG. 11 is a graph showing the time required for the catalyst converter 204 according to the fifth embodiment of the present invention and the conventional three-way catalyst to decrease from a catalyst temperature of 600 degrees Celsius to each temperature. In FIG. 11, the horizontal axis indicates time, and the vertical axis indicates the catalyst temperature. FIG. 12 is a graph (FIG. 12A) showing a quantitative and qualitative relationship between the temperature of the downstream catalyst 205 and the first target temperature of the catalytic converter 204 according to the fifth embodiment of the present invention. A graph showing a quantitative and qualitative relationship between the temperature of 204 and the temperature decrease rate of the catalytic converter 204 (FIG. 12B), and the temperature of the downstream catalyst 205 and the second target temperature of the catalytic converter 204 It is the graph (FIG.12 (c)) which showed the quantitative and qualitative relationship.

  As shown in FIG. 9, the catalyst when starting the heat treatment of the catalytic converter 204 by the electrocatalyst heater according to the fifth embodiment under the control of the control unit 190 through the above-described steps S401 to S404. A variable ksic1 indicating the heating start temperature that is the temperature of the converter 204 and a variable ksic3 indicating the heating stop temperature that is the temperature of the catalytic converter 204 when the heating process of the catalytic converter 204 by the electrocatalyst heater is stopped are acquired. (Step S501). Specifically, the variable ksic1 indicating the heating start temperature and the variable ksic3 indicating the heating stop temperature correspond to the temperature change characteristic of the catalytic converter 204 described above in addition to the variable Tufc indicating the temperature of the downstream catalyst 205. It is determined uniquely. Here, the temperature change characteristic according to the present embodiment means, for example, the degree of change when the temperature changes with time in the property related to the temperature change of an object such as the catalytic converter 204.

  Typically, the temperature change characteristic may mean a temperature decrease amount that decreases per unit time in the above-described catalytic converter 204, that is, a temperature decrease rate. Alternatively, the temperature change characteristic may mean a time interval required for the temperature of the above-described catalytic converter 204 to decrease by a predetermined temperature.

  Specifically, as shown in FIG. 10, when the temperature of the downstream catalyst 205 indicated by the variable Tufc is the temperature T0, the heating start temperature T1 indicated by the variable ksic1 and the heating stop temperature T3 indicated by the variable ksic3 ( However, T3> T2) is uniquely determined. In particular, the heating stop temperature T3, which is the temperature of the catalytic converter 204 when stopping the heat treatment of the catalytic converter 204 by the electrocatalyst heater according to the fifth embodiment, is determined by the above-described electrocatalyst heater according to the fourth embodiment. Compared with the heating stop temperature T2, which is the temperature of the catalytic converter 204 when stopping the heat treatment of the catalytic converter 204, the temperature difference α is increased. This temperature difference α can be defined based on the temperature change characteristic of the catalytic converter 204 in which the heat treatment by the electrocatalyst heater described above is executed.

  According to the research on the temperature change characteristic by the inventors of the present application, the temperature change characteristic in the catalytic converter 204 in which the heat treatment by the electrocatalyst heater is executed, typically the time required to decrease by a predetermined temperature. Has been found to be short compared to the time required for a conventional three-way catalyst such as Kojleite to decrease by a predetermined temperature. This is because the catalytic converter 204 in which the heat treatment by the electrocatalyst heater is executed includes a group of elements having high thermal conductivity such as SiC (ie, silicon carbide), and the content ratio thereof is, for example, This is because the amount is higher than that of a three-way catalyst such as kojleite.

  As a result, the temperature decrease rate, which is an example of the temperature change characteristic of the catalytic converter 204 in which the heat treatment by the electrocatalyst heater is executed, is caused by the difference in the degree of the thermal conductivity, for example, the conventional three such as cordierite. Larger than the rate of temperature decrease of the original catalyst. In particular, it has been found that the difference between the temperature decrease rate of the catalytic converter 204 in which the heat treatment by the electrocatalyst heater is performed and the temperature decrease rate of a three-way catalyst such as cordierite increases as the catalyst temperature increases. ing. Specifically, as shown by the time Ti1 in FIG. 11, for example, in the case of the catalytic converter 204, the time required to decrease by 200 degrees from 600 degrees Celsius to 400 degrees Celsius is about 350 seconds. On the other hand, as shown by time Ti2 in FIG. 11, in the case of a three-way catalyst such as cordierite, it is about 740 seconds, and the catalytic converter 204 is compared with a conventional three-way catalyst such as cordierite. It has been found that the rate at which the temperature decreases is fast. More specifically, as indicated by the slopes Slp1 and Slp3 in FIG. 11, it has been found that the higher the temperature of the catalytic converter 204, the higher the temperature decrease rate. In addition, when the temperature decrease rate of the catalytic converter 204 and the temperature decrease rate of the conventional three-way catalyst are compared at a common catalyst temperature, the temperature decrease rate of the catalytic converter 204 increases as the common catalyst temperature increases. It has been found that the temperature decreases compared to the conventional three-way catalyst. Specifically, when the catalyst temperature is 600 degrees Celsius, the difference between the temperature decrease rate of the catalytic converter 204 and the temperature decrease rate of the conventional three-way catalyst (that is, the inclination angle between the inclinations Slp1 and Slp2 in FIG. 11). The difference between the temperature decrease rate of the catalytic converter 204 and the temperature decrease rate of the conventional three-way catalyst when the catalyst temperature is 400 degrees (that is, the angle between the inclinations Slp3 and Slp4 in FIG. 11). It is found that the difference is greater than

  That is, in the fifth embodiment, energization is performed to energize the EHC 206 so that the temperature of the catalytic converter 204 approaches the second target temperature determined in accordance with the temperature decrease rate of the catalytic converter 204 in addition to the temperature of the downstream catalyst 205. Control the amount. That is, as shown in FIG. 12A, the first target temperature is increased as the temperature of the downstream catalyst 205 decreases. In addition, as shown in FIG. 12B, as described above, it has been found that the temperature decrease rate of the catalytic converter 204 increases as the temperature of the catalytic converter 204 increases. As a result, in the fifth embodiment, as shown in FIG. 12C, in addition to increasing the second target temperature as the temperature of the downstream catalyst 205 decreases, it corresponds to the temperature decrease rate of the catalytic converter 204. This is further increased by the amount (see α1, α2, α3 in FIG. 12C and the temperature difference α in FIG. 10 described above).

  As described above, in the fifth embodiment, the temperature of the catalytic converter 204 is set to the EHC 206 so as to approach the second target temperature that is higher than the first target temperature by an amount corresponding to the temperature decrease rate of the catalytic converter 204. The energization amount to be energized is controlled. Thereby, the heating stop temperature which becomes an opportunity when stopping the heat processing of the catalytic converter 204 by an electrocatalyst heater can be raised. Thereby, after the actual temperature of the catalytic converter 204 reaches the higher heating stop temperature, the temperature decreases with the passage of time, and it is possible to delay the timing when it falls below the heating start temperature. Thereby, the frequency which performs the heat processing of the catalytic converter 204 by an electrocatalyst heater can be decreased. Thereby, for example, the frequency of energizing the EHC 206 from a secondary battery such as a battery can be reduced and the energization amount can be reduced, so that the consumption of the secondary battery can be effectively reduced. Thereby, it is possible to improve the energy efficiency of the whole hybrid vehicle including the fuel consumption of the engine and the amount of power of the secondary battery. In particular, in a plug-in HV vehicle having a low opportunity and frequency of starting the engine, it is very preferable in practice to improve energy efficiency and reliability. In addition, since the torque fluctuation generated in the engine can be reduced by reducing the opportunity and frequency of starting the engine, the drivability in the hybrid vehicle can be improved.

(Sixth embodiment)
Next, with reference to FIG. 13, an operation principle of an exhaust gas purification system for a hybrid vehicle according to a sixth embodiment of the present invention will be described. FIG. 13 is a flowchart showing the flow of control processing in the control unit that performs overall control of the hybrid vehicle including the exhaust purification device according to the sixth embodiment of the present invention. Note that the control process according to the sixth embodiment may be executed simultaneously with or before or after the control process according to the fourth embodiment. Alternatively, the control process according to the sixth embodiment may be executed simultaneously with or before or after the control process according to the fifth embodiment. Further, the above-described control process shown in FIG. 13 is repeatedly executed by the control unit 190 at a predetermined cycle.

  As shown in FIG. 13, first, under the control of the control unit 190, quantitative or qualitative information indicating the remaining capacity of the battery 194, that is, a so-called battery state (ie, SOC (State of Charge)) is acquired. (Step S601).

  Next, quantitative or qualitative information indicating the measured catalyst temperature of the catalytic converter 204 in which the heat treatment by the electrocatalyst heater is executed under the control of the control unit 190 is stored as a variable Tsic in a ROM or the like. It is stored and acquired in the device (step S602).

  Next, it is determined whether regeneration is requested in the hybrid vehicle under the control of the control unit 190 (step S603). Here, when it is determined that regeneration is requested in the hybrid vehicle (step S603: Yes), under the control of the control unit 190, the heating process by the electrocatalyst heater indicated by the acquired variable Tsic is executed. It is determined whether or not the measured catalyst temperature of the catalytic converter 204 is lower than a predetermined threshold value such as 700 degrees Celsius (step S604). Here, the predetermined threshold value according to the sixth embodiment is typically a temperature that exceeds the activation temperature of the catalytic converter 204, and the thermal energy of the catalytic converter 204 is transferred through the flow of exhaust gas. It may mean a temperature at which activation of the downstream catalyst 205 can be promoted by being transmitted to the downstream catalyst 205.

  As a result of the determination in step S604, when it is determined that the measured catalyst temperature of the catalytic converter 204 that is subjected to the heat treatment by the electrocatalyst heater is smaller than a predetermined threshold value such as 700 degrees Celsius (step S604: Yes). Under the control of the control unit 190, the operation of the engine is continued in the hybrid vehicle, for example, in a light load state (step S605).

  Next, under the control of the control unit 190, ignition timing retardation control is performed in the engine control of the hybrid vehicle (step S606).

  Next, under the control of the control unit 190, it is determined whether or not the ignition timing retardation control has been completed in the engine control of the hybrid vehicle (step S607). Here, in the engine control of the hybrid vehicle, when it is determined that the execution of the ignition timing retardation control is completed (step S607: Yes), the series of control processing ends. On the other hand, if it is not determined in the engine control of the hybrid vehicle that the ignition timing retard control has been completed (step S607: No), the ignition timing is again controlled in the hybrid vehicle engine control under the control of the control unit 190. The delay angle control is performed (step S606).

  On the other hand, as a result of the determination in step S604 described above, when it is not determined that the measured catalyst temperature of the catalytic converter 204 that is subjected to the heat treatment by the electrocatalyst heater is smaller than a predetermined threshold value such as 700 degrees Celsius, that is, the catalyst When it is determined that the measured catalyst temperature of the converter 204 is larger than a predetermined threshold value such as 700 degrees Celsius (step S604: No), the ignition timing is delayed in the engine control of the hybrid vehicle under the control of the control unit 190. The execution of the angle control is stopped (step S608). Thereby, unnecessary delay angle control can be omitted as much as possible, and it is possible to quickly shift to EV traveling.

  Next, regeneration is actually performed in the hybrid vehicle under the control of the control unit 190 (step S609). In the sixth embodiment, the timing for actually shifting from the HV traveling to the EV traveling may be fixed, and the ignition timing retarding control may be performed earlier on the time axis than the fixed timing. Alternatively, after delaying the timing of actual transition from HV traveling to EV traveling, the ignition timing retarding control may be performed earlier on the time axis than the delayed timing. That is, the timing for actually shifting from the HV traveling to the EV traveling may be earlier on the time axis than the timing at which the ignition timing retardation control is actually performed.

  As described above, in the sixth embodiment, when a request to switch from HV traveling to EV traveling is generated, in other words, when deceleration operation for reducing the traveling speed is requested and regeneration is requested, the ignition timing is set as the reference value. In comparison, the retard angle control for changing to the retard angle side is performed. Here, the reference timing in the ignition timing according to the present embodiment may mean an ignition timing at which at least one of fuel efficiency and thermal efficiency is optimal. Typically, it may mean an ignition timing at which the torque generated by the internal combustion engine by the combustion of fuel becomes maximum. In the sixth embodiment, the amount of change at the time of changing to the retarded angle side is such that the ignition timing is set to the retarded side according to at least one of the travel parameters such as the pressure in the intake pipe, the engine speed, and the gear ratio. A change amount at the time of changing may be set.

  Thereby, before actually switching from HV traveling to EV traveling, the temperature of the exhaust gas can be increased, and the temperature of the downstream catalyst can be further increased by the thermal energy of the exhaust gas that has become higher in temperature. Can do. In particular, in the hybrid vehicle, the heat treatment of the downstream catalyst by the exhaust gas is performed when the hybrid vehicle is running HV, that is, when the engine is operating. Thus, it is very useful in practice that the temperature of the downstream catalyst can be further increased before actually switching from HV traveling to EV traveling without operating the engine.

  As described above, in the sixth embodiment, the temperature of the downstream catalyst can be further increased, so that the target temperature and the second target temperature of the catalytic converter 204 described above can be decreased. Typically, it is possible to reduce the heating start temperature that triggers the start of heat treatment of the catalytic converter 204 by the electrocatalyst heater. As a result, the timing at which the actual temperature of the catalytic converter 204 falls below the heating start temperature can be delayed, and thus the frequency of performing the heating process of the catalytic converter 204 by the electrocatalyst heater can be reduced. Thereby, for example, the frequency of energizing the EHC 206 from a secondary battery such as a battery can be reduced and the energization amount can be reduced, so that the consumption of the secondary battery can be effectively reduced. Thereby, it is possible to improve the energy efficiency of the whole hybrid vehicle including the fuel consumption of the engine and the amount of power of the secondary battery. In particular, in a plug-in HV vehicle having a low opportunity and frequency of starting the engine, it is very preferable in practice to improve energy efficiency and reliability.

  In addition, by performing the ignition timing retard control described above, torque fluctuations generated in the engine can be reduced, so that drivability in a hybrid vehicle can be improved.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. The purification apparatus and method are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 111 ... Power transmission gear, 112 ... Drive shaft, 114 ... Differential gear, 116, 118 ... Drive wheel, 119 ... Case, 120 ... Planetary gear, 121 ... Sun gear, 122 ... Ring gear, 123 ... Planetary pinion gear, 124 ... Planetary carrier, 125 ... Sun gear shaft, 126 ... Ring gear shaft, 127 ... Planetary carrier shaft, 128 ... Power take-off gear, 129 ... Chain belt, 132 ... Rotor, 133 ... Stator, 142 ... Rotor, 143 ... Stator, 149 ... Resolver, 150 ... Engine, 151 ... Fuel injection valve, 152 ... Combustion chamber, 154 ... Piston, 156 ... Crankshaft, 157 ... Resolver, 158 ... Igniter, 160 ... Distributor, 162 ... Spark plug, 164 ... Accelerator pedal, 164a ... Accelerator pedal Position sensor, 165 ... Brake pedal, 165a ... Brake pedal position sensor, 170 ... EFIECU, 176 ... Rotation speed sensor, 178 ... Rotation angle sensor, 179 ... Starter switch, 182 ... Shift lever, 184 ... Shift position sensor, 190 ... Control Unit: 193 ... transistor inverter, 194 ... battery, 199 ... remaining capacity detector, 200 ... suction port, 202 ... exhaust port, 204 ... catalytic converter, 205 ... catalytic converter (downstream catalyst), 204a ... catalyst temperature sensor, 205a ... Catalyst temperature sensor, 206 ... EHC, 208 ... sub muffler, 210 ... main muffler, MG1, MG2 ... motor.

Claims (10)

An electrically heated catalyst heated by energization;
A downstream catalyst provided downstream of the electrically heated catalyst;
Downstream catalyst temperature specifying means for specifying the temperature of the downstream catalyst;
Energization for controlling the energization amount of the electrically heated catalyst so that the temperature of the electrically heated catalyst approaches a first target temperature determined in accordance with the specified downstream catalyst temperature when the internal combustion engine is started An exhaust emission control device for a hybrid vehicle, comprising: an amount control means.   The energization amount control means (i) changes the energization amount so that the first target temperature becomes higher as the specified downstream catalyst temperature becomes lower, and (ii) the specified downstream catalyst The exhaust emission control device for a hybrid vehicle according to claim 1, wherein the energization amount is changed so that the first target temperature decreases as the temperature increases. The power supply means for supplying power to the electrically heated catalyst;
Determining means for determining the first target temperature according to the identified downstream catalyst temperature;
The said energization amount control means controls the said electric power supply means so that the predetermined energization amount according to the determined 1st target temperature may be supplied to the said electrically heated catalyst. 2. An exhaust emission control device for a hybrid vehicle according to 1. A stop time specifying means for specifying a stop time of the internal combustion engine;
The energization amount control means (i) changes the energization amount so that the first target temperature becomes higher as the specified stop time becomes longer, and (ii) the specified stop time becomes shorter. 4. The exhaust emission control device for a hybrid vehicle according to claim 1, wherein the energization amount is changed such that the first target temperature is lowered. 5. An electrically heated catalyst heated by energization;
A downstream catalyst provided downstream of the electrically heated catalyst;
Downstream catalyst temperature specifying means for specifying the temperature of the downstream catalyst;
The energization amount of the electric heating catalyst is controlled so that the temperature of the electric heating catalyst approaches the second target temperature determined according to the specified downstream catalyst temperature and the temperature change characteristic of the electric heating catalyst. An exhaust emission control device for a hybrid vehicle, comprising:   The energization amount control means starts energization of the electric heating catalyst when the temperature of the electric heating catalyst falls below a heating start temperature lower than the second target temperature, and the temperature of the electric heating catalyst is The hybrid vehicle according to claim 5, wherein when the heating stop temperature higher than the second target temperature is exceeded, the energization amount of the electric heating catalyst is controlled so as to stop the energization of the electric heating catalyst. Exhaust purification equipment. An internal combustion engine mounted on the vehicle;
Ignition means for igniting the fuel of the internal combustion engine;
An electric motor mounted on the vehicle;
A secondary battery that supplies electric power to the electric motor and can be charged as the vehicle travels;
Before the transition from traveling by the internal combustion engine to traveling by the electric motor, the ignition means is ignited so that the fuel is ignited at a timing retarded from a reference timing at which at least one of fuel efficiency and thermal efficiency is an optimal ignition timing. The hybrid vehicle exhaust gas purification apparatus according to claim 5 or 6, further comprising: a control means for controlling.   The control means controls the ignition means to ignite the fuel at a timing retarded from the reference timing when the temperatures of the electric heating catalyst and the downstream catalyst do not exceed a predetermined threshold, 8. The ignition means is controlled to ignite the fuel at the reference timing when the temperature of at least one of the electrically heated catalyst and the downstream catalyst exceeds the predetermined threshold value. An exhaust purification device for a hybrid vehicle. An exhaust purification method for a hybrid vehicle comprising an electrically heated catalyst heated by energization and a downstream catalyst provided downstream of the electrically heated catalyst,
A downstream catalyst temperature specifying step for specifying the temperature of the downstream catalyst;
Energization for controlling the energization amount of the electrically heated catalyst so that the temperature of the electrically heated catalyst approaches a first target temperature determined in accordance with the specified downstream catalyst temperature when the internal combustion engine is started An exhaust purification method for a hybrid vehicle, comprising: an amount control step. An exhaust purification method for a hybrid vehicle comprising an electrically heated catalyst heated by energization and a downstream catalyst provided downstream of the electrically heated catalyst,
A downstream catalyst temperature specifying step for specifying the temperature of the downstream catalyst;
The energization amount of the electric heating catalyst is controlled so that the temperature of the electric heating catalyst approaches the second target temperature determined according to the specified downstream catalyst temperature and the temperature change characteristic of the electric heating catalyst. An exhaust gas purification method for a hybrid vehicle, comprising: an energization amount control step.

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