JP5733222B2 - Control device for hybrid system - Google Patents

Description

  The present invention relates to a control device for a hybrid system mounted on a vehicle.

  Conventionally, a hybrid system having an internal combustion engine and an electric motor as a drive source of a vehicle is known. Further, as an exhaust purification catalyst provided in an exhaust passage of an internal combustion engine, an electrically heated catalyst (hereinafter also referred to as EHC) in which the catalyst is heated by a heating element that generates heat when energized is developed. Has been.

  In Patent Document 1, as a method for purifying a filter that is provided in an exhaust passage of an internal combustion engine and removes particulate matter (PM) in exhaust gas, when the filter is heated to burn PM adhering to the filter, In a region where the average temperature in the filter is 100 ° C. or higher, a technique is disclosed in which the average temperature increase rate in the filter is 100 ° C./min or less.

  In Patent Document 2, in an internal combustion engine in which an exhaust gas sensor in which a heater for heating is attached to a detection element is provided in an exhaust pipe, immediately after the engine is started, a portion in the vicinity of the heater and a surface portion away from the heater are provided. A technique for performing warm-up control for controlling the temperature of the heater so that the temperature difference does not exceed a predetermined value is disclosed. Further, in Patent Document 2, during the warm-up control period, the air-fuel ratio of the air-fuel mixture used for combustion is corrected to a richer side than during normal operation, or the ignition timing is delayed from that during normal operation. It is disclosed.

JP 09-287433 A JP 2004-360526 A

  As a hybrid system mounted on a vehicle, there is a system including a generator that generates electric power using power output from an internal combustion engine and an inverter. The inverter converts DC power supplied from the battery into AC power and supplies it to the electric motor. The inverter converts AC power supplied from the generator into DC power and supplies it to the battery.

  Here, the lower the temperature of the inverter, the lower the allowable power (withstand voltage). Therefore, when the temperature of the inverter is low at the time of cold start of the internal combustion engine, if the amount of power generated by the generator increases rapidly as the output of the internal combustion engine increases, the power supplied from the generator to the inverter exceeds the allowable range. As a result, there is a risk that the inverter will fail.

  On the other hand, when the EHC is provided in the exhaust passage of the internal combustion engine, the heating element is heated by the energy of the exhaust even if the EHC is not energized. However, when the heating element is heated by the energy of the exhaust, the side wall surface of the heating element has a large amount of heat radiation, so that the temperature is less likely to rise compared to the inside. Therefore, at the time of cold start of the internal combustion engine where the temperature of the EHC (temperature of the heating element) is low, if the amount of energy input to the heating element by the exhaust increases rapidly as the output of the internal combustion engine increases, the side of the heating element There is a possibility that the temperature difference between the wall surface and the inside becomes excessively large and cracks are generated in the heating element.

In EHC, when a crack occurs in the heating element, the electric resistance value of the cracked portion becomes higher than that of other portions. Therefore, when the EHC is energized, the distribution of the energization amount in the heating element becomes non-uniform. As a result, a larger temperature difference occurs in the heating element, which may increase or increase cracks.

  The present invention has been made in view of the above problems, and in a hybrid system in which an EHC is provided in an exhaust passage of an internal combustion engine, when the internal combustion engine is cold started, a crack is generated in the EHC heating element. It is an object of the present invention to provide a technique capable of suppressing the occurrence of an inverter and also preventing the occurrence of a malfunction of an inverter.

The control device of the hybrid system according to the present invention includes:
A control device for a hybrid system mounted on a vehicle,
The hybrid system
An internal combustion engine and an electric motor as a drive source of the vehicle;
A generator for generating power by the power output from the internal combustion engine;
An inverter that converts DC power supplied from a battery to AC power and supplies the electric motor, and converts AC power supplied from the generator to DC power and supplies the battery to the battery. ,
The exhaust passage of the internal combustion engine is provided with an electrically heated catalyst in which the catalyst is heated by a heating element that generates heat when energized,
When the internal combustion engine is cold started, the intake air amount of the internal combustion engine is reduced if the input energy amount suppression condition, which is a condition for suppressing the amount of energy input to the electrically heated catalyst, is satisfied. By performing either control or control for reducing the air-fuel ratio of the air-fuel mixture without reducing the intake air amount of the internal combustion engine, the amount of energy input to the electrically heated catalyst by exhaust is suppressed. With a control unit,
In the cold start of the internal combustion engine, in addition to the input energy amount suppression condition, if a supply power suppression condition that is a condition for suppressing the power supplied from the generator to the inverter is satisfied, the control The control unit selects and executes the control for reducing the intake air amount of the internal combustion engine.

  When the intake air amount of the internal combustion engine is reduced, the flow rate of the exhaust gas is also reduced. Therefore, by executing the control for reducing the intake air amount of the internal combustion engine, the amount of energy input to the EHC by the exhaust can be suppressed. Further, when the air-fuel ratio of the air-fuel mixture in the internal combustion engine is lowered, the temperature of the exhaust gas is lowered. Therefore, even if the intake air amount of the internal combustion engine is not reduced, the amount of energy input to the EHC by the exhaust gas can be suppressed by executing the control for reducing the air-fuel ratio of the air-fuel mixture.

  However, if the air-fuel ratio of the air-fuel mixture is reduced without reducing the intake air amount of the internal combustion engine, the output of the internal combustion engine may increase. In the hybrid system according to the present invention, when the output of the internal combustion engine increases, the power generation amount of the generator increases. As a result, the electric power supplied from the generator to the inverter increases.

  Therefore, in the present invention, when the supply power suppression condition is satisfied in addition to the input energy amount suppression condition, the control unit selects and executes the control for reducing the intake air amount of the internal combustion engine. Decreasing the intake air amount of the internal combustion engine can suppress an increase in the output of the internal combustion engine. Therefore, by selecting and executing the control for reducing the intake air amount of the internal combustion engine, it is possible to suppress the amount of energy input to the EHC and also suppress the power supplied to the inverter. Therefore, it is possible to suppress the occurrence of cracks in the EHC heating element during the cold start of the internal combustion engine, and it is also possible to suppress the occurrence of a malfunction of the inverter.

  In the present invention, at the time of cold start of the internal combustion engine, if the input energy amount suppression condition is satisfied and the supply power suppression condition is not satisfied, the control unit performs mixing without reducing the intake air amount of the internal combustion engine. Control for lowering the air-fuel ratio of the air may be selected and executed.

  When the control for reducing the intake air amount of the internal combustion engine is executed, an increase in the output of the internal combustion engine is suppressed. On the other hand, when the control for reducing the air-fuel ratio of the air-fuel mixture is performed without reducing the intake air amount of the internal combustion engine, the amount of energy input to the EHC by the exhaust is suppressed without suppressing the increase in the output of the internal combustion engine. be able to. Therefore, according to the above, it is possible to suppress the occurrence of cracks in the EHC heating element without suppressing an increase in output during a cold start of the internal combustion engine.

  The control device of the hybrid system according to the present invention may further include an inverter heater and a heater control unit. The inverter heater heats the inverter when the power supply suppression condition is satisfied at the cold start of the internal combustion engine. As the temperature of the inverter increases, the allowable power increases. Therefore, the power supply suppression condition can be established earlier by heating the inverter with the inverter heater. As a result, the output of the internal combustion engine can be increased more quickly.

  However, even if the supply power suppression condition is not satisfied, if the input energy amount suppression condition is satisfied, it is necessary to suppress an increase in the output of the internal combustion engine in order to suppress the energy input to the EHC by the exhaust gas. That is, even if the inverter is heated by the inverter heater, the output of the internal combustion engine cannot be quickly increased.

  Therefore, in the above case, the heater control unit may prohibit heating of the inverter by the inverter heater when the input energy amount suppression condition is satisfied in addition to the supply power suppression condition at the cold start of the internal combustion engine. Good. According to this, useless heating of the inverter by the inverter heater can be suppressed.

  The input energy amount suppression condition in the present invention is that the amount of energy input to the EHC according to the required output of the internal combustion engine at the time of cold start of the internal combustion engine exceeds the upper limit of the allowable amount of EHC. There may be. Further, the power supply suppression condition in the present invention is that the power supplied from the generator to the inverter according to the required output of the internal combustion engine at the time of cold start of the internal combustion engine exceeds the upper limit value of the power that can be allowed by the inverter. It may be that.

  Here, the required output of the internal combustion engine is an output corresponding to the accelerator opening of the vehicle. The greater the required output of the internal combustion engine, the greater the amount of energy input to the EHC and the power supplied from the generator to the inverter. The upper limit value of the input energy amount that the EHC can tolerate and the upper limit value of the power that the inverter can tolerate can be obtained in advance based on experiments or the like.

  Further, the input energy amount suppression condition in the present invention may be that the required output of the internal combustion engine at the time of cold start of the internal combustion engine exceeds a threshold determined based on the temperature of the EHC. Further, the power supply suppression condition in the present invention may be that the required output of the internal combustion engine at the time of cold start of the internal combustion engine exceeds a threshold determined based on the temperature of the inverter. In these cases, each threshold value increases as the EHC temperature or the inverter temperature increases.

According to the present invention, in the hybrid system in which the EHC is provided in the exhaust passage of the internal combustion engine, it is possible to suppress the occurrence of cracks in the EHC heating element during the cold start of the internal combustion engine, and It is also possible to suppress the occurrence of defects.

1 is a diagram showing a schematic configuration of a hybrid system and an intake / exhaust system of an internal combustion engine according to Embodiment 1. FIG. 1 is a diagram illustrating a schematic configuration of an EHC according to Embodiment 1. FIG. FIG. 6 is a diagram for explaining a transition of the temperature of the EHC catalyst carrier during a cold start of the internal combustion engine according to the first embodiment. FIG. 3A is a cross-sectional view when the EHC is cut in a direction perpendicular to the axial direction. FIG. 3 (b) is a graph showing the transition of the temperature of the catalyst carrier during the cold start of the internal combustion engine. FIG. 3 (c) is a graph showing the transition of the temperature difference between the side wall surface of the catalyst carrier and the side wall near the inside thereof during the cold start of the internal combustion engine. 2 is a flowchart showing a control flow at the time of cold start of the internal combustion engine according to the first embodiment. It is a figure which shows the relationship between the temperature Tehc of EHC and EHC allowable upper limit output pwec based on Example 1. FIG. It is a figure which shows the relationship between the temperature Tinv of an inverter, and inverter allowable upper limit output pwinv based on Example 1. FIG. It is a figure which shows schematic structure of the hybrid system which concerns on Example 2, and the intake / exhaust system of an internal combustion engine. 7 is a flowchart showing a control flow during cold start of an internal combustion engine according to a second embodiment.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

<Example 1>
[Schematic configuration of intake and exhaust system of hybrid system and internal combustion engine]
FIG. 1 is a diagram showing a schematic configuration of a hybrid system and an intake / exhaust system of an internal combustion engine according to the present embodiment. The hybrid system 50 according to the present embodiment includes an internal combustion engine 1, a power split mechanism 51, an electric motor 52, a generator 53, a battery 54, an inverter 55, an axle 56, a speed reducer 57, and wheels 58.

  The power split mechanism 51 distributes the output from the internal combustion engine 1 to the generator 53 and the axle 56. The generator 53 generates power using the power output from the internal combustion engine 1. The power split mechanism 51 also has a function of transmitting the output from the electric motor 52 to the axle 56. The electric motor 52 rotates at a rotational speed proportional to the axle 56 via the speed reducer 57. The electric motor 52 can assist the output of the internal combustion engine 1 as necessary during normal operation. A battery 54 is connected to the electric motor 52 and the generator 53 via an inverter 55.

  The inverter 55 converts the DC power supplied from the battery 54 into AC power and supplies it to the electric motor 52. Further, the inverter 55 converts AC power supplied from the generator 53 into DC power and supplies it to the battery 54. Thereby, the battery 54 is charged. The inverter 55 is provided with a water temperature sensor 59 that detects the cooling water temperature of the inverter 55.

In the hybrid system 50 configured as described above, the wheel 56 is driven by rotating the axle 56 by the output of the internal combustion engine 1 or the output of the electric motor 52. Further, the wheel 56 can be driven by rotating the axle 56 in accordance with the output of the internal combustion engine 1 and the output of the electric motor 52. Further, the crankshaft of the internal combustion engine 1 can be rotated by the output of the electric motor 52.

  The internal combustion engine 1 is a gasoline engine having four cylinders. Each cylinder is provided with a fuel injection valve (not shown) for injecting fuel into the intake port. In addition, an intake pipe 10 and an exhaust pipe 11 are connected to the internal combustion engine 1. The intake pipe 10 is provided with an air flow meter 12 and a throttle valve 13. The air flow meter 12 detects the intake air amount of the internal combustion engine 1. The throttle valve 13 adjusts the intake air amount of the internal combustion engine 1.

  The exhaust pipe 11 is provided with EHC2. The configuration of EHC 2 will be described later. An exhaust pipe 11 upstream of the EHC 2 is provided with an A / F sensor 14 and a first exhaust temperature sensor 15. A second exhaust temperature sensor 16 is provided in the exhaust pipe 11 downstream of the EHC 2. The A / F sensor 14 detects the air-fuel ratio of the exhaust. The first and second exhaust temperature sensors 15 and 16 detect the temperature of the exhaust.

  The hybrid system 50 includes an electronic control unit (ECU) 20. A water temperature sensor 59, an air flow meter 12, an A / F sensor 14, a first exhaust temperature sensor 15, and a second exhaust temperature sensor 16 are electrically connected to the ECU 20. Furthermore, an accelerator opening sensor 17 that detects the accelerator opening of the vehicle 100 is electrically connected to the ECU 20. And the output value of these sensors is input into ECU20.

  The ECU 20 is electrically connected to the power split mechanism 51, the throttle valve 13, and the fuel injection valve of the internal combustion engine 1. These devices are controlled by the ECU 20.

[Schematic configuration of EHC]
FIG. 2 is a diagram showing a schematic configuration of EHC2. Note that the arrows in FIG. 2 indicate the flow direction of the exhaust gas in the exhaust pipe 11.

  The EHC 2 includes a catalyst carrier 3, a case 4, a mat 5, an inner tube 6, and an electrode 7. The catalyst carrier 3 is accommodated in the case 4. The catalyst carrier 3 is formed in a columnar shape, and is installed so that its central axis is coaxial with the central axis A of the exhaust pipe 2. The central axis A is a central axis common to the exhaust pipe 2, the catalyst carrier 3, the inner pipe 6, and the case 4. A three-way catalyst 31 is supported on the catalyst carrier 3. The catalyst supported on the catalyst carrier 3 is not limited to a three-way catalyst, and may be an oxidation catalyst, an occlusion reduction type NOx catalyst, or a selective reduction type NOx catalyst.

  The catalyst carrier 3 is formed of a material that generates electric resistance and generates heat when energized. An example of the material of the catalyst carrier 3 is SiC. The catalyst carrier 3 has a plurality of passages extending in the direction in which the exhaust flows (that is, in the direction of the central axis A) and having a cross section perpendicular to the direction in which the exhaust flows in a honeycomb shape. Exhaust gas flows through this passage. The cross-sectional shape of the catalyst carrier 3 in the direction orthogonal to the central axis A may be an ellipse or the like.

  A pair of electrodes 7 are connected to the outer peripheral surface of the catalyst carrier 3. The electrode 7 is formed by a surface electrode 7a and a shaft electrode 7b. The surface electrode 7 a extends in the circumferential direction and the axial direction along the outer peripheral surface of the catalyst carrier 3. The surface electrodes 7 a are provided on the outer peripheral surface of the catalyst carrier 3 so as to face each other with the catalyst carrier 3 interposed therebetween. One end of the shaft electrode 7b is connected to the surface electrode 7a. The other end of the shaft electrode 7 b protrudes outside the case 4 through the electrode chamber 9 formed in the case 4.

Electricity is supplied to the electrode 7 from the battery 54 via the supply power control unit 18. When electricity is supplied to the electrode 7, the catalyst carrier 3 is energized. When the catalyst carrier 3 generates heat by energization, the three-way catalyst 31 supported on the catalyst carrier 3 is heated, and its activation is promoted. The supply power control unit 18 is electrically connected to the ECU 20, and performs ON / OFF switching of supply of electricity to the electrode 7 (that is, energization to the catalyst carrier 3) and adjustment of supply power.

  The case 4 is made of metal. As a material for forming the case 4, a stainless steel material can be exemplified. A mat 5 is sandwiched between the inner wall surface of the case 4 and the outer peripheral surface of the catalyst carrier 3. That is, the catalyst carrier 3 is supported by the mat 5 in the case 4. An inner tube 6 is sandwiched between the mats 5. The inner tube 6 is a tubular member centered on the central axis A. The mat 5 is divided into the case 4 side and the catalyst carrier 3 side by the inner tube 6 by sandwiching the inner tube 6.

  The mat 5 is formed of an electrical insulating material. Examples of the material for forming the mat 5 include ceramic fibers mainly composed of alumina. The mat 5 is wound around the outer peripheral surface of the catalyst carrier 3 and the outer peripheral surface of the inner tube 6. The mat 5 is divided into an upstream portion 5a and a downstream portion 5b, and a space is formed between the upstream portion 5a and the downstream portion 5b. Since the mat 5 is sandwiched between the catalyst carrier 3 and the case 4, electricity is suppressed from flowing to the case 4 when the catalyst carrier 3 is energized.

  The inner tube 6 is made of a stainless steel material. In addition, an electrical insulating layer is formed on the entire surface of the inner tube 6. Examples of the material for forming the electrical insulating layer include ceramic or glass. The main body of the inner tube 6 may be formed of an electrical insulating material such as alumina. The inner pipe 6 is not necessarily provided.

  The case 4 and the inner tube 6 have through holes for passing the shaft electrode 7b. An electrode chamber 9 is formed by a space in the case 4 between the upstream portion 5 a and the downstream portion 5 b of the mat 5. That is, in this embodiment, the electrode chamber 9 is formed over the entire outer peripheral surface of the catalyst carrier 3 between the upstream portion 5a and the downstream portion 5b of the mat 5. In addition, without dividing the mat 5 into the upstream portion 5a and the downstream portion 5b, a space serving as an electrode chamber may be formed by forming a through hole only in a portion through which the electrode 7 of the mat 5 passes.

  An electrode support member 8 that supports the shaft electrode 7 b is provided in the through hole opened in the case 4. The electrode support member 8 is made of an electrical insulating material, and is provided between the case 4 and the electrode 7 without a gap.

  In this embodiment, the catalyst carrier 3 corresponds to a heating element according to the present invention. However, the heating element according to the present invention is not limited to the carrier supporting the catalyst. For example, the heating element may be a structure installed on the upstream side of the catalyst.

[Control during cold start of internal combustion engine]
Next, control when the internal combustion engine 1 is cold started will be described. At the time when the internal combustion engine 1 is cold-started, the temperature of the EHC 2 (the temperature of the catalyst carrier 3) is also low. When the internal combustion engine 1 is started, the temperature of the EHC 2 is raised by the exhaust gas even when the EHC 2 is not energized.

FIG. 3 is a view for explaining the transition of the temperature of the catalyst carrier 3 of the EHC 2 when the internal combustion engine 1 is cold started. FIG. 3A is a cross-sectional view when the EHC 2 is cut in a direction perpendicular to the axial direction. In FIG. 3A, illustration of the electrode 7 and the inner tube 6 is omitted for convenience. FIG. 3 (b) is a diagram showing the transition of the temperature of the catalyst carrier 3 when the internal combustion engine 1 is cold started. In FIG. 3B, the horizontal axis represents time, and the vertical axis represents the temperature of the catalyst carrier 3. 3B, the alternate long and short dash line represents the temperature of the side wall surface of the catalyst carrier 3 (the surface in contact with the mat 5), and the broken line represents the temperature in the vicinity of the side wall inside the catalyst carrier 3. The solid line represents the temperature of the central portion of the catalyst carrier 3. FIG. 3 (c) is a diagram showing the transition of the temperature difference between the side wall surface of the catalyst carrier 3 and the side wall vicinity thereof when the internal combustion engine 1 is cold started. In FIG. 3C, the horizontal axis represents time, and the vertical axis represents the temperature difference ΔT between the side wall surface of the catalyst carrier 3 and the side wall near the inside thereof.

  When the temperature of the catalyst carrier 3 is increased by exhaust, the side wall surface of the catalyst carrier 3 has a large amount of heat released to the mat 5, and therefore the temperature is less likely to rise compared to the inside. Therefore, as shown in FIG. 3, when the internal combustion engine 1 is cold-started, when the amount of energy input to the catalyst carrier 3 by the exhaust increases rapidly with the increase in the output of the internal combustion engine 1, A temperature difference occurs between the inside and the inside. In particular, the temperature difference between the side wall surface of the catalyst carrier 3 and the vicinity of the side wall inside the catalyst carrier 3 tends to increase. If the temperature difference between the side wall surface and the inside of the catalyst carrier 3 becomes excessively large, cracks may occur in the catalyst carrier 3.

  In EHC2, when a crack occurs in the catalyst carrier 3, the electric resistance value of the cracked portion becomes higher than that of the other portions. Therefore, when the EHC 2 is energized, the distribution of the energization amount in the catalyst carrier 3 becomes non-uniform. As a result, a larger temperature difference occurs in the catalyst carrier 3 and there is a risk of increasing or increasing cracks.

  Therefore, in this embodiment, when the predetermined input energy amount suppression condition is satisfied at the time of cold start of the internal combustion engine 1, the intake air amount reduction is performed in order to suppress the energy amount input to the EHC 2 by the exhaust gas. Control of either control or air-fuel ratio lowering control is executed. The intake air amount reduction control is a control for reducing the intake air amount of the internal combustion engine 1 from the air amount corresponding to the required output by reducing the opening of the throttle valve 13. In the internal combustion engine 1 that is a gasoline engine, the air-fuel ratio of the air-fuel mixture of the internal combustion engine 1 is controlled with the stoichiometric air-fuel ratio as the target air-fuel ratio during normal operation. The air-fuel ratio lowering control is a control for lowering the air-fuel ratio of the air-fuel mixture of the internal combustion engine 1 below the stoichiometric air-fuel ratio by increasing the fuel injection amount without reducing the intake air amount of the internal combustion engine 1.

  When the intake air amount of the internal combustion engine 1 is reduced, the flow rate of the exhaust gas is also reduced. Therefore, by executing the intake air amount reduction control, the amount of energy input to the EHC 2 by exhaust can be suppressed. On the other hand, when the air-fuel ratio of the air-fuel mixture of the internal combustion engine 1 is made lower than the stoichiometric air-fuel ratio, the exhaust temperature decreases. Therefore, the amount of energy input to the EHC 2 by the exhaust can be suppressed by executing the air-fuel ratio lowering control. By suppressing the amount of energy input to the EHC 2 by exhaust, the temperature rise of the entire catalyst carrier 3 can be moderated. Therefore, the temperature difference between the side wall surface and the inside of the catalyst carrier 3 can be reduced. As a result, generation of cracks in the catalyst carrier 3 can be suppressed.

  Further, when the internal combustion engine 1 is cold-started, the temperature of the inverter 55 of the hybrid system 50 may be low. The lower the temperature of the inverter 55, the lower the allowable power (withstand voltage). Accordingly, when the temperature of the inverter 55 is low during the cold start of the internal combustion engine 1, if the amount of power generated by the generator 53 increases rapidly as the output of the internal combustion engine 1 increases, the power is supplied from the generator 53 to the inverter 55. There is a possibility that the inverter 55 may malfunction if the electric power exceeds the allowable range. Therefore, when the internal combustion engine 1 is cold started, it may be necessary to suppress the power supplied from the generator 53 to the inverter 55.

Therefore, in this embodiment, when the internal combustion engine 1 is cold-started, in addition to the input energy amount suppression condition, a supply power suppression condition that is a condition for suppressing the power supplied from the generator 53 to the inverter 55 is established. If so, intake air amount reduction control is selected and executed from intake air amount reduction control or air-fuel ratio reduction control.

  When the air-fuel ratio reduction control is executed, the exhaust temperature can be reduced as described above, but the output of the internal combustion engine 1 may be increased because the fuel injection amount increases. Therefore, the amount of power generated by the generator 53 increases, and there is a risk that the power supplied from the generator 53 to the inverter 55 increases. On the other hand, when the intake air amount reduction control is executed, the exhaust flow rate can be reduced as described above, and the increase in the output of the internal combustion engine 1 can be suppressed. Therefore, the amount of power generated by the generator 53 can be suppressed. Therefore, the amount of energy input to the EHC 2 can be suppressed, and the power supplied from the generator 53 to the inverter 55 can also be suppressed. Therefore, when the internal combustion engine 1 is cold started, the occurrence of cracks in the catalyst carrier 3 of the EHC 2 can be suppressed, and the occurrence of a malfunction of the inverter 55 can also be suppressed.

  On the other hand, in this embodiment, when the input energy amount suppression condition is satisfied at the time of cold start of the internal combustion engine 1, but the supply power suppression condition is not satisfied, the intake air amount decrease control or the air-fuel ratio decrease control is performed. Of these, air-fuel ratio lowering control is selected and executed. According to this, the amount of energy input to the EHC 2 can be suppressed without suppressing an increase in the output of the internal combustion engine 1. Therefore, when the internal combustion engine 1 is cold-started, it is possible to suppress the occurrence of cracks in the catalyst carrier 3 of the EHC 2 while rapidly increasing the output of the internal combustion engine 1.

  Here, the input energy amount suppression condition and the supply power suppression condition will be described. The higher the output of the internal combustion engine 1, the higher the temperature of the exhaust gas and the higher the flow rate of the exhaust gas. Therefore, the larger the output of the internal combustion engine 1, the larger the amount of energy input to the EHC 2 by the exhaust. Further, the lower the temperature of the EHC 2 (the temperature of the catalyst carrier 3), the larger the temperature difference between the side wall surface and the inside of the catalyst carrier 3 when the amount of energy input to the catalyst carrier 3 increases.

  Therefore, in this embodiment, when the required output of the internal combustion engine 1 during the cold start of the internal combustion engine 1 exceeds a threshold determined based on the temperature of the EHC 2, the input energy amount suppression condition is satisfied. Judge. Here, the threshold value is a value that, when the output of the internal combustion engine 1 becomes the threshold value, the amount of energy input to the EHC 2 by the exhaust gas is an upper limit value that the EHC 2 can tolerate. Hereinafter, this threshold value is referred to as an EHC allowable upper limit output.

  Further, as described above, as the output of the internal combustion engine 1 increases, the amount of power generated by the generator 53 increases, and the power supplied from the generator 53 to the inverter 55 increases. And the allowable electric power (withstand voltage) of the inverter 55 decreases as the temperature of the inverter 55 decreases.

  Therefore, in this embodiment, when the required output of the internal combustion engine 1 at the time of cold start of the internal combustion engine 1 exceeds a threshold determined based on the temperature of the inverter 55, the supply power suppression condition is satisfied. Judge. Here, the threshold value is a value at which the power supplied from the generator 53 to the inverter 55 becomes the upper limit value of the power that can be allowed by the inverter when the output of the internal combustion engine 1 becomes the threshold value. Hereinafter, this threshold is referred to as an inverter allowable upper limit output.

  It should be noted that the EHC allowable upper limit output, which is a criterion value for determining whether the input energy amount suppression condition is satisfied, and the inverter allowable upper limit, which is a criterion value for determining whether the supply power suppression condition is satisfied, as described above. The output is determined as the output of the internal combustion engine 1 when the air-fuel ratio of the air-fuel mixture of the internal combustion engine 1 is the stoichiometric air-fuel ratio.

[Control flow]
A control flow at the time of cold start of the internal combustion engine 1 according to the present embodiment will be described based on a flowchart shown in FIG. This flow is stored in advance in the ECU 20 and is repeatedly executed by the ECU 20.

  In this flow, first, in step S101, it is determined whether or not the internal combustion engine 1 has been cold started. Here, it may be determined that the engine is cold started when the internal combustion engine 1 is started in a state where the temperature of the cooling water of the internal combustion engine 1 is equal to or lower than a predetermined temperature. If a negative determination is made in step S101, the execution of this flow is temporarily terminated.

  On the other hand, when an affirmative determination is made in step S101, the process of step S102 is executed next. In step S102, the required output pwre of the internal combustion engine 1 is calculated based on the accelerator opening detected by the accelerator opening sensor 17.

  Next, in step S103, the temperature Tehc of the EHC 2 is calculated based on at least one of the exhaust temperature detected by the first exhaust temperature sensor 15 and the exhaust temperature detected by the second exhaust temperature sensor 16. Next, in step S104, an EHC allowable upper limit output pwec is calculated based on the temperature Tehc of EHC2.

  FIG. 5 is a diagram showing the relationship between the temperature Tehc of EHC2 and the EHC allowable upper limit output pwec. As shown in FIG. 5, the lower the temperature of EHC2, the smaller the EHC allowable upper limit output pwec becomes. Such a relationship between the temperature Tehc of the EHC 2 and the EHC allowable upper limit output pwec is obtained in advance based on experiments or the like, and is stored in the ECU 20 as a map or a function. In step S104, the EHC allowable upper limit output pwec is calculated using this map or function.

  Next, in step S105, the temperature Tinv of the inverter 55 is calculated based on the coolant temperature of the inverter 55 detected by the water temperature sensor 59. Next, in step S106, the inverter allowable upper limit output pwinv is calculated based on the temperature Tinv of the inverter 55.

  FIG. 6 is a diagram showing the relationship between the temperature Tinv of the inverter 55 and the inverter allowable upper limit output pwinv. As shown in FIG. 6, the inverter allowable upper limit output pwinv becomes smaller as the temperature Tinv of the inverter 55 is lower. Such a relationship between the temperature Tinv of the inverter 55 and the inverter allowable upper limit output pwinv is obtained in advance based on experiments or the like, and is stored in the ECU 20 as a map or a function. In step S106, the inverter allowable upper limit output pwinv is calculated using this map or function.

  Next, in step S107, it is determined whether the required output pwre of the internal combustion engine 1 exceeds the EHC allowable upper limit output pwec. If an affirmative determination is made in step S107, it can be determined that the input energy amount suppression condition is satisfied. In this case, the process of step S108 is performed next. On the other hand, if a negative determination is made in step S107, it can be determined that the input energy amount suppression condition is not satisfied. In this case, the process of step S111 is performed next.

  In step S108, it is determined whether or not the required output pwre of the internal combustion engine 1 exceeds the inverter allowable upper limit output pwinv. When an affirmative determination is made in step S108, it can be determined that the supply power suppression condition is satisfied in addition to the input energy amount suppression condition. In this case, the process of step S109 is performed next.

In step S109, intake air amount reduction control is executed. As a result, the amount of energy input to the EHC 2 by the exhaust is suppressed and the power supplied from the generator 53 to the inverter 55 is also suppressed.

  On the other hand, when a negative determination is made in step S108, it can be determined that only the input energy amount suppression condition is satisfied and the supply power suppression condition is not satisfied. In this case, the process of step S110 is performed next.

  In step S110, air-fuel ratio reduction control is executed. As a result, the amount of energy input to the EHC 2 by the exhaust gas is suppressed without suppressing an increase in the output of the internal combustion engine 1.

  In step S111, it is determined whether the required output pwre of the internal combustion engine 1 exceeds the inverter allowable upper limit output pwinv. When an affirmative determination is made in step S111, it can be determined that the input energy amount suppression condition is not satisfied and only the supply power suppression condition is satisfied. In this case, the process of step S109 is performed next.

  On the other hand, when a negative determination is made in step S111, since it can be determined that neither the input energy amount suppression condition nor the supply power suppression condition is satisfied, the execution of this flow is temporarily terminated. In this case, the output of the internal combustion engine 1 is controlled to the required output pwre.

<Example 2>
[Schematic configuration of intake and exhaust system of hybrid system and internal combustion engine]
FIG. 7 is a diagram showing a schematic configuration of the hybrid system and the intake / exhaust system of the internal combustion engine according to the present embodiment. The hybrid system 50 according to this embodiment is provided with an inverter heater 60 that heats the inverter 55. The inverter heater 60 is an electric heater that is driven by using the battery 54 as a power source. The inverter heater 60 is electrically connected to the ECU 20 and is controlled by the ECU 20.

  The configuration other than the inverter heater 60 is the same as that of the first embodiment. Also in the present embodiment, similarly to the first embodiment, when a predetermined condition is satisfied at the time of cold start of the internal combustion engine 1, intake air reduction control or air-fuel ratio decrease control is executed.

[Inverter heater control]
As described above, the lower the temperature of the inverter 55, the lower the allowable power (withstand voltage). Therefore, in this embodiment, when the supply power suppression condition is satisfied when the internal combustion engine 1 is cold started, intake air amount reduction control is executed and the inverter 55 is heated by the inverter heater 60.

  By being heated by the inverter heater 60, the temperature of the inverter 55 rises more quickly. When the temperature of the inverter 55 rises, the inverter allowable upper limit output pwinv rises. Therefore, by heating the inverter 55 by the inverter heater 60, the supply power suppression condition can be established earlier. As a result, the output of the internal combustion engine 1 can be increased more quickly.

  However, even if the supply power suppression condition is not satisfied, if the input energy amount suppression condition is satisfied, it is necessary to suppress an increase in the output of the internal combustion engine 1 in order to suppress the energy input to the EHC 2 by the exhaust gas. That is, even if the inverter 55 is heated by the inverter heater 60, the output of the internal combustion engine 1 cannot be quickly increased.

Thus, in this embodiment, when the internal combustion engine 1 is cold started, heating of the inverter 55 by the inverter heater 60 is prohibited when the input energy amount suppression condition is satisfied in addition to the supply power suppression condition. According to this, useless heating of the inverter 55 by the inverter heater 60 can be suppressed.

[Control flow]
A control flow at the time of cold start of the internal combustion engine 1 according to the present embodiment will be described based on a flowchart shown in FIG. This flow is stored in advance in the ECU 20 and is repeatedly executed by the ECU 20. This flow is obtained by adding steps S209 and S210 to the flow shown in FIG. For this reason, only the processing in steps S209 and S210 will be described, and description of the other steps will be omitted.

  In this flow, if an affirmative determination is made in step S108, that is, if both the input energy amount suppression condition and the supply power suppression condition are satisfied, the process of step S209 is then executed. In step S209, the inverter heater 60 is turned off. That is, heating of the inverter 55 by the inverter heater 60 is prohibited. Then, in step S109, intake air intake amount reduction control is executed.

  Further, in this flow, when an affirmative determination is made in step S111, that is, when the input energy amount suppression condition is not satisfied and only the supply power suppression condition is satisfied, the process of step S210 is then executed. The In step S210, the inverter heater 60 is turned on. Thereby, the inverter 55 is heated by the inverter heater 60. In this case also, the intake air intake amount reduction control is executed in step S109.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Electric heating type catalyst (EHC)
3 ... Catalyst carrier 7 ... Electrode 10 ... Intake pipe 11 ... Exhaust pipe 12 ... Air flow meter 13 ... Throttle valve 14 ... A / F sensor 15 ... First exhaust temperature sensor 16 ... Two exhaust temperature sensors 18 ..Supply power control unit 31..Three-way catalyst 50..Hybrid system 51..Power split mechanism 52.Electric motor 53.Generator 54.Battery 55.Inverter 56.Axle 57 ·· Reducer 58 · · Wheel 59 · · Water temperature sensor 100 · · Vehicle

Claims (7)

A control device for a hybrid system mounted on a vehicle,
The hybrid system
An internal combustion engine and an electric motor as a drive source of the vehicle;
A generator for generating power by the power output from the internal combustion engine;
An inverter that converts DC power supplied from a battery to AC power and supplies the electric motor, and converts AC power supplied from the generator to DC power and supplies the battery to the battery. ,
The exhaust passage of the internal combustion engine is provided with an electrically heated catalyst in which the catalyst is heated by a heating element that generates heat when energized,
When the internal combustion engine is cold started, the intake air amount of the internal combustion engine is reduced if the input energy amount suppression condition, which is a condition for suppressing the amount of energy input to the electrically heated catalyst, is satisfied. By performing either control or control for reducing the air-fuel ratio of the air-fuel mixture without reducing the intake air amount of the internal combustion engine, the amount of energy input to the electrically heated catalyst by exhaust is suppressed. With a control unit,
In the cold start of the internal combustion engine, in addition to the input energy amount suppression condition, if a supply power suppression condition that is a condition for suppressing the power supplied from the generator to the inverter is satisfied, the control The control unit of the hybrid system, wherein the unit selects and executes the control for reducing the intake air amount of the internal combustion engine.   When the input energy amount suppression condition is satisfied and the supply power suppression condition is not satisfied at the time of cold start of the internal combustion engine, the control unit performs mixing without reducing the intake air amount of the internal combustion engine. 2. The control apparatus for a hybrid system according to claim 1, wherein the control for reducing the air-fuel ratio of the air is selected and executed. At the time of cold start of the internal combustion engine, when the supply power suppression condition is satisfied, an inverter heater that heats the inverter;
In the cold start of the internal combustion engine, in addition to the supply power suppression condition, if the input energy amount suppression condition is satisfied, a heater control unit that prohibits heating of the inverter by the inverter heater;
The control apparatus of the hybrid system of Claim 1 or 2 provided with these.   The input energy amount suppression condition is that the input energy amount to the electric heating catalyst according to the required output of the internal combustion engine at the time of cold start of the internal combustion engine is an upper limit of an amount that the electric heating catalyst can accept The control device for a hybrid system according to any one of claims 1 to 3, wherein the value exceeds the value.   The supply power suppression condition is such that the supply power from the generator to the inverter according to the required output of the internal combustion engine at the time of cold start of the internal combustion engine exceeds the upper limit value of power that the inverter can allow The hybrid system control device according to claim 1, wherein the control device is a hybrid system control device.   4. The input energy amount suppression condition is that the required output of the internal combustion engine at a cold start of the internal combustion engine exceeds a threshold value determined based on the temperature of the electric heating catalyst. The control apparatus of the hybrid system as described in any one of Claims.   5. The power supply suppression condition is that the required output of the internal combustion engine at a cold start of the internal combustion engine exceeds a threshold determined based on the temperature of the inverter. The control apparatus of the hybrid system described in 1.

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