Method for controlling a hybrid system, and control device for a hybrid system

Abstract

The present invention provides a control method for a hybrid system that can suppress the warm-up operation of the catalytic converter when the engine is restarted, and a control device for a hybrid system. [Solution] The hybrid system control method and hybrid system control device according to the present invention restrict the introduction of fresh air by completely closing the negative pressure generating valve 31, and by motoring, the high-temperature exhaust gas is recirculated to the intake side (intake passage 3) via the EGR passage, thereby suppressing the supply of fresh air to the catalyst 41 and preventing a drop in the temperature of the catalyst 41. This makes it possible to suppress the warm-up operation of the catalyst 41 when restarting the engine 1.

Description

Technical Field

[0001] The present invention relates to a control method for a hybrid system and a control device for a hybrid system.

Background Art

[0002] As a conventional control method for a hybrid system, for example, the one described in Patent Document 1 below is known.

[0003] In this conventional control method for a hybrid system, when the state of charge of the battery reaches the upper limit value during regeneration, the throttle valve is opened and the EGR valve is closed to increase the engine friction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the case of the conventional control method for an internal combustion engine, when the engine is idling due to motoring, fresh air is supplied to the catalyst and the temperature decreases, resulting in a decrease in the purification performance of the catalyst. Therefore, there is still room for improvement in that a warm-up operation of the catalyst is required when the engine is restarted.

[0006] Therefore, the present invention has been devised in view of the technical problems of the conventional control method for a hybrid system, and an object thereof is to provide a control method for a hybrid system and a control device for a hybrid system that can suppress the warm-up operation of the catalyst when the engine is restarted.

Means for Solving the Problems

[0007] In one aspect, the present invention provides a control method for a hybrid system comprising: a supercharger provided in an exhaust passage; a catalyst provided downstream of the supercharger in the exhaust passage for purifying exhaust gas; an EGR valve provided in an EGR passage branching from the downstream of the catalyst in the exhaust passage for opening and closing the EGR passage; a throttle valve provided in an intake passage for controlling the amount of intake air introduced into the cylinder; and a negative pressure generating valve provided upstream of the compressor of the supercharger in the intake passage, wherein when the battery charge level reaches an upper limit, the system controls the discharge by running the engine idle by motoring, wherein when the battery charge level of the hybrid system reaches an upper limit, the temperature of the catalyst is measured, and when the temperature of the catalyst falls below a first threshold, the engine is burned for only one cycle to fully open the EGR valve and the throttle valve, and fully close the negative pressure generating valve.

[0008] Furthermore, in another aspect, the present invention provides a control method for a hybrid system comprising: a catalyst provided in an exhaust passage for purifying exhaust gas; an EGR valve provided in an EGR passage branching from the downstream side of the catalyst in the exhaust passage for opening and closing the EGR passage; and a throttle valve provided in an intake passage for controlling the amount of intake air introduced into the cylinder, wherein when the battery charge level reaches an upper limit, the system controls the discharge by running the engine idle by motoring, wherein when the battery charge level reaches an upper limit, the temperature of the catalyst is measured, and when the temperature of the catalyst falls below a first threshold, the engine is burned for only one cycle to fully open the EGR valve and fully close the throttle valve. [Effects of the Invention]

[0009] According to the present invention, by restricting the introduction of fresh air and recirculating high-temperature gas to the intake side via the EGR passage through motoring, the supply of fresh air to the catalyst is suppressed, thereby suppressing the temperature drop of the catalyst. This makes it possible to suppress the warm-up operation of the catalyst when the engine is restarted. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram illustrating the configuration of a hybrid system to which the present invention is applied. [Figure 2] This is a schematic diagram showing the configuration of the intake and exhaust passages of a supercharged gasoline engine according to the first embodiment of the present invention. [Figure 3] This is a time chart of engine control according to the first embodiment of the present invention. [Figure 4] This is a schematic diagram showing the configuration of the intake and exhaust passages of a naturally aspirated gasoline engine according to a second embodiment of the present invention. [Figure 5] This is a time chart of engine control according to the second embodiment of the present invention. [Modes for carrying out the invention]

[0011] Embodiments of the control method for a hybrid system and the control device for a hybrid system according to the present invention will be described in detail below with reference to the drawings.

[0012] (Hybrid system configuration) Figure 1 shows a system configuration diagram of a hybrid system to which the present invention is applied.

[0013] For example, as shown in Figure 1, a vehicle V to which the present invention is applied has a drive unit DU that drives the drive wheels WR and WL, and a power generation unit GU that generates electricity to drive the drive wheels WR and WL.

[0014] The drive unit DU includes a drive motor DM, which acts as a second electric motor to rotate the drive wheels WR and WL, and a first gear train GT1 and differential gear DF, which transmit the driving force of the drive motor DM to the drive wheels WR and WL. Power is supplied to the drive motor DM from a battery VT, which is charged with electricity generated by the power generation unit GU.

[0015] The power generation unit GU includes a generator GE as a first electric motor that generates electric power for supplying the drive motor DM, an engine 1 that drives the generator GE, and a second gear train GT2 that transmits the rotation of the engine 1 to the generator GE.

[0016] From the above configuration, the vehicle V is a so-called series hybrid vehicle that does not use the engine 1 as a power source, and the engine 1 is mounted on the vehicle for power generation. Therefore, when the charge rate of the battery VT decreases, for example, the vehicle V drives the engine 1 to generate power with the generator GE to charge the battery VT.

[0017] 〔First Embodiment〕 FIG. 2 shows a schematic diagram showing the configuration of the intake and exhaust passages of a gasoline engine equipped with a supercharger according to the present embodiment.

[0018] (Configuration of the engine) For example, as shown in FIG. 2, the engine 1 according to the present embodiment is a spark ignition engine equipped with a turbocharger 2 as a supercharger. An air cleaner (not shown) is arranged at the inlet portion serving as the upstream end in the intake passage 3 of the engine 1, and a compressor 21 of the turbocharger 2 is arranged in the middle of the intake passage 3.

[0019] Further, a negative pressure generation valve 31 for generating a negative pressure in the region between the compressor 21 is provided upstream of the compressor 21 in the intake passage 3. The negative pressure generation valve 31 has a so-called butterfly valve type configuration, and the opening degree is controlled by an engine controller 5 as a control device (control unit) via an electric actuator so as to generate a required negative pressure according to the operating conditions of the engine 1. That is, by providing this negative pressure generation valve 31, it is possible to generate a required negative pressure according to the operating conditions of the engine 1, which contributes to the appropriate reflux of blow-by gas and EGR gas.

[0020] Also, a throttle valve 32 for controlling the intake air amount of the engine 1 is disposed downstream of the compressor 21 in the intake passage 3. The throttle valve 32 is a so-called electronically controlled throttle valve that includes an electric actuator such as a motor and whose opening degree is controlled by an engine controller 5 which is a control device.

[0021] Furthermore, a water-cooled intercooler 33 is provided between the throttle valve 3 and the intake port 11 of the engine 1 downstream of the compressor 21 in the intake passage 3. The intercooler 33 cools the intake air compressed by the compressor 21 through heat exchange with the cooling water flowing through the interior.

[0022] On the other hand, a turbine 22 of a turbocharger 2 is provided in the exhaust passage 4 of the engine 1. Also, a catalyst 41 made of a three-way catalyst and an exhaust particulate filter (GPF) 42 coated with the three-way catalyst are provided downstream of the turbine 22 in the exhaust passage 4. Further, an air-fuel ratio sensor (not shown) for detecting the air-fuel ratio is disposed upstream of the exhaust passage 4.

[0023] Moreover, the engine 1 is provided with a well-known EGR passage 6 for recirculating a part of the exhaust gas from the exhaust passage 4 to the intake passage 3. One end of the EGR passage 6 is connected, for example, between the catalyst 41 and the exhaust particulate filter 42 in the exhaust passage 4, and the other end of the EGR passage 6 is connected upstream of the compressor 21 in the intake passage 3. Further, the EGR passage 6 is provided with, for example, a water-cooled EGR cooler 61 for cooling the EGR gas and an EGR valve 62 for controlling the recirculation amount of the EGR gas. The opening degree of the EGR valve is controlled by the engine controller 5.

[0024] The engine controller 5 is a control device that manages engine control, and receives detection signals from various sensors, such as a throttle position sensor 51 that detects the throttle opening, a crank angle sensor 52 that detects the rotational speed of the engine 1, an air-fuel ratio sensor 53 that detects the exhaust air-fuel ratio in the exhaust passage 4, a water temperature sensor 54 that detects the coolant temperature, and an intake air temperature sensor 55 that detects the intake air temperature. The engine controller 5 then performs various controls on the engine 1, such as controlling the fuel injection amount and injection timing by a fuel injector (not shown), controlling the ignition timing by a spark plug (not shown), controlling the opening amount of the negative pressure generating valve 31 and the throttle valve 32, and controlling the boost pressure of the turbocharger 2.

[0025] (Control method for hybrid systems) Figure 3 is a time chart showing the motoring-induced idle control of the engine 1 when the battery VT's charge rate (SOC) reaches its upper limit Vx in the hybrid system according to this embodiment. Column (a) shows the SOC, i.e., the charge rate (charge state) of the battery VT; (b) shows the temperature of the catalyst 41; (c) shows the opening degree of the negative pressure generating valve 31; (d) shows the opening degree of the throttle valve 32; (e) shows the opening degree of the EGR valve 62; (f) shows the combustion state of the engine 1; and (g) shows the temperature of the exhaust gas at the outlet of the engine 1's exhaust port (not shown).

[0026] For example, as shown in Figure 3, the regenerative action of the vehicle V increases the charge rate of the battery VT (battery charge rate SOC), and at time t1 when this battery charge rate SOC reaches the upper limit Vx, the temperature of the catalyst 41 (catalyst temperature CT) is at a second threshold Cx2, which is greater than the first threshold Cx1. At this time, the negative pressure generating valve 31 and the throttle valve 32 are open (negative pressure generating valve opening AV=1, throttle valve opening TV=1), and the EGR valve 62 is fully closed (EGR valve opening EV=0). As a result, the engine 1 does not burn (combustion state EF=0), and the temperature of the exhaust gas at the outlet of the engine 1 (exhaust port 12) (exhaust gas temperature GT) is relatively low.

[0027] From the above state, after time t1 when the battery charge level (SOC) reaches the upper limit value Vx, the engine 1 is run idle by motoring. As a result, the negative pressure generating valve 31 and the throttle valve 32 are open (negative pressure generating valve opening AV=1, throttle valve opening TV=1) and the engine 1 is run idle, allowing fresh air to be introduced from the intake port 11 through the intake passage 3, causing the catalyst temperature CT to gradually decrease. Then, at time t2 when the catalyst temperature CT reaches a first threshold Cx1 which is higher than the catalyst function maintenance standard value Cx, the engine 1 is burned for at least one cycle (combustion state EF=1).

[0028] In this case, it is desirable that the combustion of engine 1 be performed for only one cycle, but depending on the catalyst temperature CT state, it may be possible to perform multiple cycles. Furthermore, it is desirable that the torque generated during the combustion of engine 1 be a negative torque to suppress the decrease in the load on the generator GE. In addition, it is desirable to use canister purge gas, which is fuel adsorbed in a canister (not shown), when operating the combustion of engine 1.

[0029] Thus, after the engine 1 has been running for one combustion cycle at time t2, the negative pressure generating valve 31 is fully closed (negative pressure generating valve opening AV=0), and the throttle valve 32 and EGR valve 62 are fully opened (throttle valve opening TV=1, EGR valve opening EV=1). As a result, the introduction of fresh air is restricted by the closing of the negative pressure generating valve 31, the catalyst 41 is heated by the high-temperature exhaust gas discharged by the combustion operation of the engine 1, and the high-temperature exhaust gas is returned to the intake passage 3 through the EGR passage 6 by the opening of the EGR valve 62, causing the catalyst temperature CT to rise. Then, after the combustion operation of the engine 1, when the catalyst temperature CT exceeds the second threshold Cx2, the combustion of the engine 1 is terminated.

[0030] Furthermore, when recirculating exhaust gas through the EGR passage 6, it is desirable to stop the circulation of the cooling water flowing through the EGR cooler 61 and the intercooler 33. In other words, by stopping the circulation of the cooling water flowing through the EGR cooler 61 and the intercooler 33, the temperature drop of the exhaust gas recirculated through the EGR passage 6 can be suppressed.

[0031] Thus, when the combustion operation of the engine 1 ends, the introduction of fresh air is restricted because the negative pressure generating valve 31 remains closed (negative pressure generating valve opening AV=0). However, the catalyst temperature CT gradually decreases due to the decrease in exhaust gas temperature GT associated with the cooling of the engine 1 over time.

[0032] Subsequently, as the catalyst temperature CT decreases, at time t3 when the catalyst temperature CT reaches the first threshold Cx1 again, the negative pressure generating valve 31 is opened (negative pressure generating valve opening AV=1) and the EGR valve 62 is fully closed (EGR valve opening TV=0), allowing the engine 1 to operate for one or more combustion cycles. After the combustion operation of the engine 1, as with time t2 onward, the negative pressure generating valve 31 is fully closed (negative pressure generating valve opening AV=0) and the throttle valve 32 and EGR valve 62 are fully opened (throttle valve opening TV=1, EGR valve opening EV=1), thereby recirculating the high-temperature exhaust gas discharged from the combustion of the engine 1 back into the intake passage 3 and raising the catalyst temperature CT.

[0033] As described above, according to the control method of the hybrid system in this embodiment, until the next time the engine 1 is started, when the battery charge rate SOC reaches the upper limit Vx during motoring, if the catalyst temperature CT falls below the first threshold Cx1, the engine 1 is run for one or more cycles to raise the catalyst temperature CT, and when the catalyst temperature CT exceeds the second threshold Cx2, the combustion of the engine 1 is stopped. This control is repeated. In this way, in conjunction with motoring when the battery charge rate SOC reaches the upper limit Vx, the catalyst 41 is warmed up until the engine 1 is restarted, and the optimal temperature state of the warmed catalyst 41 is maintained.

[0034] (Effects of this embodiment) With the above configuration, in this embodiment, by completely closing the negative pressure generating valve 31 to restrict the introduction of fresh air, and by motoring, the high-temperature exhaust gas is recirculated to the intake side (intake passage 3) via the EGR passage, thereby suppressing the supply of fresh air to the catalyst 41 and preventing a drop in the temperature of the catalyst 41. As a result, a warm-up operation of the catalyst 41 when restarting the engine 1 is unnecessary. Consequently, a decrease in the purification performance of the catalyst 41 is suppressed, the emission of unpurified exhaust gas associated with the warm-up operation of the catalyst 41 is suppressed, and the deterioration of fuel efficiency caused by the warm-up operation of the catalyst 41 is suppressed.

[0035] Furthermore, when warming up the catalytic converter 41, the purification capacity is insufficient until the catalytic converter 41 warms up, which limits the output of the engine 1 (the amount of combustion is limited). As a result, there is a risk that the engine may not be able to output sufficient engine torque to meet the driver's demands when needed.

[0036] In contrast, in this embodiment, the catalyst 41 is warmed up in conjunction with motoring that occurs when the battery charge level (SOC) reaches the upper limit value Vx, and the optimal temperature state of the warmed catalyst 41 is maintained, eliminating the need for a warm-up operation of the catalyst 41 when the engine 1 is restarted. As a result, sufficient engine torque can be obtained in response to the driver's demands when needed.

[0037] Furthermore, in this embodiment, during combustion of the engine 1 while motoring, the EGR valve 62 is fully closed, and the negative pressure generating valve 31 and throttle valve 32 are opened to introduce fresh air into the cylinder, thereby ensuring proper combustion of the engine 1. This makes it possible to suppress misfires in the engine 1.

[0038] Furthermore, in this embodiment, by making the torque generated during combustion of engine 1 during motoring negative, it is possible to suppress the decrease in the load on generator GE. As a result, the decrease in the amount of regeneration during vehicle V deceleration is suppressed, and the decrease in the feeling of deceleration during that deceleration can be suppressed.

[0039] Furthermore, in this embodiment, when the catalyst temperature CT falls below a first threshold Cx1, the engine 1 is combusted for one cycle or a relatively small number of cycles, and when the catalyst temperature CT rises above a second threshold Cx2, which is greater than the first threshold Cx1, the combustion is terminated. In this way, by limiting the combustion of the engine 1 during motoring to the bare minimum necessary, fuel consumption associated with the combustion operation of the engine 1 during motoring can be reduced.

[0040] Furthermore, in this embodiment, the engine 1 is configured not to burn when the catalyst temperature CT is higher than the first threshold Cx1. By thus preventing unnecessary combustion of the engine 1 during motoring, fuel consumption associated with the combustion operation of the engine 1 during motoring can be reduced.

[0041] Furthermore, in this embodiment, when EGR gas is circulating during motoring, the circulation of cooling water flowing through the intercooler 33 and EGR cooler 61 is stopped. In this way, during the warm-up control of the catalyst 41 during motoring, the EGR gas recirculated to the intake side is kept from being cooled as much as possible, thereby suppressing the temperature drop of the catalyst 41 and maintaining the catalyst 41 at an optimal temperature.

[0042] Furthermore, in this embodiment, the fuel adsorbed in the canister (canister purge gas) is used when the engine 1 burns during motoring. This makes it possible to reduce fuel consumption associated with the combustion of the engine 1 during motoring.

[0043] [Second Embodiment] Figures 4 and 5 show a second embodiment of the control method for a hybrid system and a control device for a hybrid system according to the present invention, applying the present invention to a naturally aspirated engine without a turbocharger 2. Note that the basic configuration is the same as in the first embodiment, except for the fact that it is a naturally aspirated engine without a turbocharger 2. Therefore, the same reference numerals are used for components identical to those in the first embodiment, and their descriptions are omitted.

[0044] (Engine configuration) Figure 4 shows a schematic diagram illustrating the configuration of the intake and exhaust passages of a naturally aspirated gasoline engine according to this embodiment. For example, as shown in Figure 4, the engine 1' according to this embodiment is the same as the supercharged engine 1 (see Figure 2) illustrated in the first embodiment, but with the turbocharger 2 and intercooler 33 removed.

[0045] (Control method for hybrid systems) Figure 5 is a time chart showing the motoring control of the engine 1' when the battery VT's charge rate (SOC) reaches its upper limit Vx in the hybrid system according to this embodiment. Column (a) shows the SOC, i.e., the charge rate (charge state) of the battery VT; (b) shows the temperature of the catalyst 41; (c) shows the opening degree of the throttle valve 32; (d) shows the opening degree of the EGR valve 62; (e) shows the combustion state of the engine 1; and (f) shows the temperature of the exhaust gas at the outlet of the engine 1's exhaust port (not shown).

[0046] For example, as shown in Figure 5, the regenerative action of the vehicle V increases the charge rate of the battery VT (battery charge rate SOC), and at time t1 when this battery charge rate SOC reaches the upper limit Vx, the temperature of the catalyst 41 (catalyst temperature CT) is at a second threshold Cx2, which is greater than the first threshold Cx1. At this time, the throttle valve 32 is in the open state (throttle valve opening TV=1) and the EGR valve 62 is in the fully closed state (EGR valve opening EV=0). As a result, the engine 1' is not burning (combustion state EF=0), and the temperature of the exhaust gas at the outlet of the engine 1' (exhaust port 12) (exhaust gas temperature GT) is relatively low.

[0047] From the above state, after time t1 when the battery charge level (SOC) reaches the upper limit value Vx, the engine 1 is run idle by motoring. As a result, with the throttle valve 32 open (throttle valve opening TV=1), the engine 1' is run idle, and fresh air is introduced from the intake port 11 through the intake passage 3, causing the catalyst temperature CT to gradually decrease. Then, at time t2 when the catalyst temperature CT reaches a first threshold Cx1 which is higher than the catalyst function maintenance standard value Cx, the engine 1' is burned for at least one cycle (combustion state EF=1).

[0048] In this case, it is desirable that the combustion of engine 1' be performed for only one cycle, but depending on the catalyst temperature CT state, it may be possible to perform multiple cycles. Furthermore, it is desirable that the torque generated during the combustion of engine 1' be a negative torque to suppress the decrease in the load on the generator GE. In addition, it is desirable to use canister purge gas, which is fuel adsorbed in a canister (not shown), when operating the combustion of engine 1'.

[0049] Thus, after the engine 1' has been running for one combustion cycle at time t2, the throttle valve 32 is fully closed (throttle valve opening TV=0) and the EGR valve 62 is fully opened (EGR valve opening EV=1). As a result, the introduction of fresh air is restricted by the closing of the throttle valve 32, the catalyst 41 is heated by the high-temperature exhaust gas discharged by the combustion operation of the engine 1', and the high-temperature exhaust gas is returned to the intake passage 3 through the EGR passage 6 by the opening of the EGR valve 62, causing the catalyst temperature CT to rise. Then, after the combustion operation of the engine 1', when the catalyst temperature CT exceeds the second threshold Cx2, the combustion of the engine 1' is terminated.

[0050] Furthermore, when recirculating exhaust gas through the EGR passage 6, it is desirable to stop the circulation of the cooling water flowing inside the EGR cooler 61. In other words, by stopping the circulation of the cooling water flowing inside the EGR cooler 61, the temperature drop of the exhaust gas recirculated through the EGR passage 6 can be suppressed.

[0051] Thus, once the combustion operation of engine 1' is completed, the introduction of fresh air is restricted by the continued closed state of the throttle valve 32 (throttle valve opening TV = 0). However, the catalytic converter temperature CT gradually decreases due to the decrease in exhaust gas temperature GT associated with the cooling of engine 1' over time.

[0052] Subsequently, as the catalyst temperature CT decreases, at time t3 when the catalyst temperature CT reaches the first threshold Cx1 again, the throttle valve 32 is opened (throttle valve opening TV=1) and the EGR valve 62 is fully closed (EGR valve opening EV=0), allowing the engine 1' to operate for one or more combustion cycles. After the combustion operation of the engine 1', as with time t2 onward, the throttle valve 32 is fully closed (throttle valve opening TV=0) and the EGR valve 62 is fully opened (EGR valve opening TV=1), thereby recirculating the high-temperature exhaust gas discharged from the combustion of the engine 1' back into the intake passage 3 and raising the catalyst temperature CT.

[0053] As described above, according to the control method of the hybrid system in this embodiment, until the next start of the engine 1', when the battery charge level SOC reaches the upper limit Vx during motoring, if the catalyst temperature CT falls below the first threshold Cx1, the engine 1' is run for one or more cycles to raise the catalyst temperature CT, and when the catalyst temperature CT exceeds the second threshold Cx2, the combustion of the engine 1' is stopped. This control is repeated. In this way, in conjunction with motoring when the battery charge level SOC reaches the upper limit Vx, the catalyst 41 is warmed up until the engine 1' is restarted, and the optimal temperature state of the warmed catalyst 41 is maintained.

[0054] (Effects of this embodiment) As described above, in this embodiment as well, by completely closing the throttle valve 32 to restrict the introduction of fresh air, and by motoring to recirculate the high-temperature exhaust gas to the intake side (intake passage 3) via the EGR passage, the supply of fresh air to the catalyst 41 is suppressed, and the temperature drop of the catalyst 41 can be suppressed. As a result, the warm-up operation of the catalyst 41 when restarting the engine 1' becomes unnecessary. Consequently, the deterioration of the purification performance of the catalyst 41 is suppressed, the emission of unpurified exhaust gas associated with the warm-up operation of the catalyst 41 is suppressed, and the deterioration of fuel efficiency caused by the warm-up operation of the catalyst 41 can be suppressed.

[0055] Furthermore, in this embodiment, during combustion of the engine 1 while motoring, the EGR valve 62 is fully closed, and the negative pressure generating valve 31 and throttle valve 32 are opened to introduce fresh air into the cylinder, thereby ensuring proper combustion of the engine 1. This makes it possible to suppress misfires in the engine 1.

[0056] Furthermore, in this embodiment, when EGR gas is circulating during motoring, the circulation of cooling water flowing through the EGR cooler 61 is stopped. In this way, during the warm-up control of the catalyst 41 during motoring, the EGR gas recirculated to the intake side is kept from being cooled as much as possible, thereby suppressing the temperature drop of the catalyst 41 and maintaining the catalyst 41 at an optimal temperature.

[0057] Furthermore, the same effects and benefits as those of the first embodiment are achieved in other aspects as well.

[0058] The present invention is not limited to the configurations exemplified in the above embodiments, and can be freely modified according to the specifications of the hybrid system to which the present invention is applied. [Explanation of Symbols]

[0059] 1, 1'... Engine 2… Turbocharger (supercharger) 3…Intake passage 31… Negative pressure generating valve 32… Throttle valve 33... Intercooler 4… Exhaust passage 41…Catalyst 5…Engine controller (control unit) 6…EGR passage 61…EGR cooler 62…Catalyst VT...Battery SOC…charging rate Cx1...First threshold Cx2...Second threshold Vx... Upper limit

Claims

1. A supercharger installed in the exhaust passage, A catalyst for purifying exhaust gas is provided in the exhaust passage downstream of the supercharger, An EGR valve is provided in the EGR passage that branches off from the downstream side of the catalyst in the exhaust passage, and opens and closes the EGR passage. A throttle valve is provided in the intake passage and controls the amount of intake air directed into the cylinder, A negative pressure generating valve is provided in the intake passage upstream of the compressor of the supercharger, A control method for a hybrid system that includes a mechanism to discharge the battery by running the engine idle using motoring when the battery charge level reaches its upper limit, When the charge level of the battery reaches its upper limit, the temperature of the catalyst is measured. When the temperature of the catalyst falls below a first threshold, the engine is burned for only one cycle, the EGR valve and the throttle valve are fully opened, and the negative pressure generating valve is fully closed. Control methods for hybrid systems.

2. A catalyst is installed in the exhaust passage to purify the exhaust gas, An EGR valve is provided in the EGR passage that branches off from the downstream side of the catalyst in the exhaust passage, and opens and closes the EGR passage. A throttle valve is provided in the intake passage and controls the amount of intake air directed into the cylinder, A control method for a hybrid system that includes a mechanism to discharge the battery by running the engine idle using motoring when the battery charge level reaches its upper limit, When the charge level of the battery reaches its upper limit, the temperature of the catalyst is measured. When the temperature of the catalyst falls below a first threshold, the engine is burned for only one cycle, the EGR valve is fully opened, and the throttle valve is fully closed. Control methods for hybrid systems.

3. A control method for a hybrid system according to claim 1, During combustion caused by the engine running idle, the EGR valve is completely closed, while the throttle valve and the negative pressure generating valve are opened to introduce fresh air into the cylinder. Control methods for hybrid systems.

4. A control method for a hybrid system according to claim 2, During combustion caused by the engine running idle, the EGR valve is fully closed, and the throttle valve is opened to introduce fresh air into the cylinder. Control methods for hybrid systems.

5. A control method for a hybrid system according to claim 1 or 2, The torque generated during combustion caused by the engine running idle is considered negative. Control methods for hybrid systems.

6. A control method for a hybrid system according to claim 1 or 2, When the temperature of the catalyst falls below the first threshold, the engine is combusted in one cycle or a relatively small number of cycles. When the temperature of the catalyst reaches a second threshold, which is greater than the first threshold, the combustion is terminated. Control methods for hybrid systems.

7. A control method for a hybrid system according to claim 1 or 2, If the temperature of the catalyst is higher than the first threshold, the engine will not be combusted. Control methods for hybrid systems.

8. A control method for a hybrid system according to claim 1, A water-cooled intercooler is provided between the throttle valve and the engine in the intake passage, An EGR cooler provided in the aforementioned EGR passage, Furthermore, When EGR gas is circulating through the aforementioned EGR passage, the circulation of cooling water flowing through the intercooler and the EGR cooler is stopped. Control methods for hybrid systems.

9. A control method for a hybrid system according to claim 2, An EGR cooler is provided in the aforementioned EGR passage. When EGR gas is circulating through the EGR passage, the circulation of cooling water flowing through the EGR cooler is stopped. Control methods for hybrid systems.

10. A control method for a hybrid system according to claim 1 or 2, During combustion caused by the engine running idle, canister purge gas is used. Control methods for hybrid systems.

11. A supercharger installed in the exhaust passage, A catalyst for purifying exhaust gas is provided in the exhaust passage downstream of the supercharger, An EGR valve is provided in the EGR passage that branches off from the downstream side of the catalyst in the exhaust passage, and opens and closes the EGR passage. A throttle valve is provided in the intake passage and controls the amount of intake air directed into the cylinder, A negative pressure generating valve is provided in the intake passage upstream of the compressor of the supercharger, A control device for a hybrid system that includes a mechanism that, when the battery charge level reaches its upper limit, discharges the battery by running the engine idle using motoring, The control unit measures the temperature of the catalyst when the battery's charge level reaches its upper limit. When the temperature of the catalyst falls below a first threshold, the control unit burns the engine for only one cycle, fully opening the EGR valve and the throttle valve, and fully closing the negative pressure generating valve. Control unit for the hybrid system.

12. A catalyst is installed in the exhaust passage to purify the exhaust gas, An EGR valve is provided in the EGR passage that branches off from the downstream side of the catalyst in the exhaust passage, and opens and closes the EGR passage. A throttle valve is provided in the intake passage and controls the amount of intake air directed into the cylinder, A control device for a hybrid system that includes a mechanism that, when the battery charge level reaches its upper limit, discharges the battery by running the engine idle using motoring, The battery has a control unit that measures the temperature of the catalyst when the battery's charge level reaches its upper limit. When the temperature of the catalyst falls below a first threshold, the control unit burns the engine for only one cycle, fully opens the EGR valve, and fully closes the throttle valve. Control unit for the hybrid system.

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