Control method for hybrid vehicles and control device for hybrid vehicles

Abstract

To improve the regeneration of exhaust particulate filters in hybrid vehicles. [Solution] When a regeneration request for the exhaust particulate filter 8 occurs, if the temperature of the exhaust particulate filter 8 is in a regeneration prohibited region where regeneration of the exhaust particulate filter 8 is prohibited, the vehicle performs load reduction control to reduce the load of the internal combustion engine 1 during operation by a predetermined amount. When the temperature of the exhaust particulate filter 8 is reduced by the load reduction control to the regeneration target temperature T1 where regeneration is permitted, the vehicle starts motoring the internal combustion engine 1 to start regeneration of the exhaust particulate filter 8.

Description

Technical Field

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

Background Art

[0002] For example, Patent Document 1 discloses a technique for suppressing the filter temperature by restricting the intake air amount of a diesel engine when the temperature of a particulate collection filter becomes too high during filter regeneration for burning and removing the particulates collected by the particulate collection filter.

[0003] However, the diesel engine of Patent Document 1 is not mounted on a so-called hybrid vehicle, and in Patent Document 1, no consideration is given to the battery SOC of the in-vehicle battery during filter regeneration.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When regenerating an exhaust particulate filter mounted on a hybrid vehicle, if an attempt is made to perform regeneration of the exhaust particulate filter by restricting the intake air amount so that the exhaust particulate filter does not become excessively high temperature in a state where the battery SOC is low, the power generation amount may decrease due to a decrease in the output of the engine (internal combustion engine), which may have an adverse effect on the drivability of the vehicle.

[0006] That is, there is room for further improvement in performing the regeneration process of the exhaust particulate filter mounted on a hybrid vehicle.

Means for Solving the Problems

[0007] The hybrid vehicle of the present invention includes an internal combustion engine that can be motorized by an electric motor, and an exhaust particulate filter arranged in the exhaust passage to collect exhaust particulate matter in the exhaust gas. When the temperature of the exhaust particulate filter is above a predetermined regeneration prohibition temperature at which regeneration of the exhaust particulate filter is prohibited, and the battery SOC of the onboard battery is above a predetermined first battery SOC threshold, and the amount of exhaust particulate matter collected by the exhaust particulate filter is above a predetermined collection amount threshold, a regeneration request for the exhaust particulate filter is generated, the hybrid vehicle implements load reduction control to reduce the load of the internal combustion engine by a predetermined amount, thereby cooling the exhaust particulate filter. [Effects of the Invention]

[0008] The hybrid vehicle of the present invention enables the exhaust particulate filter to be regenerated as quickly as possible, even in high-temperature conditions where regeneration of the exhaust particulate filter is not permitted when a regeneration request for the exhaust particulate filter arises. Therefore, the hybrid vehicle can suppress the amount of exhaust particulate matter collected between the time a regeneration request for the exhaust particulate filter arises and the start of regeneration of the exhaust particulate filter, thereby reducing the capacity margin of the exhaust particulate filter and reducing the capacity of the exhaust particulate filter. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram illustrating the system configuration of an internal combustion engine installed in a hybrid vehicle according to the present invention. [Figure 2] An explanatory diagram showing the relationship between the upper threshold for permitted regeneration and the target temperature for regeneration. [Figure 3] A timing chart showing an example of changes in various state quantities during the regeneration of an exhaust particulate filter. [Figure 4] A schematic diagram illustrating the correlation between the amount of exhaust particulate matter collected by the exhaust particulate filter and the temperature of the exhaust particulate filter. [Figure 5] A flowchart illustrating the control flow during the regeneration of the exhaust particulate filter. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0011] Figure 1 is a schematic diagram illustrating the system configuration of an internal combustion engine 1 installed in a hybrid vehicle (hereinafter simply referred to as "vehicle") according to the present invention.

[0012] The internal combustion engine 1 is mounted on a vehicle for power generation and generates electricity by driving an electric motor (motor generator) (not shown). The electricity generated by this electric motor is supplied to a battery (not shown) mounted on the vehicle or to a drive motor that drives the vehicle's drive wheels. The electricity generated and supplied to the battery is used to charge the battery. The electric motor is equivalent to a generator and is capable of motorizing the internal combustion engine 1. The internal combustion engine 1 has an intake passage 2 and an exhaust passage 3. The internal combustion engine 1 uses gasoline as fuel, for example.

[0013] The intake passage 2 is equipped with an electrically operated first throttle valve 4 and an electrically operated second throttle valve 5 located upstream of the first throttle valve 4. The first throttle valve 4 controls the amount of intake air to the internal combustion engine 1 according to the load. The second throttle valve 5 is equivalent to a pressure control valve and controls the intake pressure upstream of the compressor, which will be described later. The second throttle valve 5 is also positioned downstream in the direction of intake air flow from the connection point between the intake passage 2 and the EGR passage 12, which will be described later.

[0014] In the exhaust passage 3, the following are arranged in series from upstream in the direction of exhaust flow: a first exhaust gas purification catalyst 6, an electroheated catalyst (EHC) 7, an exhaust particulate filter 8, and a second exhaust gas purification catalyst 9.

[0015] The first exhaust purification catalyst 6 and the second exhaust purification catalyst 9 are, for example, composed of a three-way catalyst. The three-way catalyst can simultaneously purify NOx, HC, and CO in the exhaust with the maximum conversion efficiency when the air-fuel ratio is within a so-called window centered on the stoichiometric air-fuel ratio. Further, the second exhaust purification catalyst 9 is, for example, an underfloor catalyst composed of a three-way catalyst.

[0016] The electric heating catalyst 7 is a catalyst that generates heat by being energized. For example, a ceramic heating element that generates heat by being energized is used as a catalyst carrier, and an appropriate catalyst metal that becomes a three-way catalyst or an oxidation catalyst is coated on its surface as a slurry.

[0017] The exhaust particulate filter 8 is a GPF (Gasoline Particulate Filter) that collects soot, which is exhaust particulate matter (Particulate Matter) in the exhaust, and is capable of burning and removing the collected soot for regeneration under predetermined conditions. When the temperature of the exhaust particulate filter 8 reaches or exceeds a predetermined combustible temperature Tf, the combustion and removal of the deposited (collected) exhaust particulate matter become possible.

[0018] The internal combustion engine 1 has a turbocharger 10 as a supercharger. The turbocharger 10 has a compressor (not shown) on the intake passage 2 and a turbine (not shown) on the exhaust passage 3 arranged coaxially and rotating integrally. The compressor is located upstream of the first throttle valve 4 in the flow direction of the intake air and downstream of the second throttle valve 5 in the flow direction of the intake air. The turbine is arranged upstream of the first exhaust purification catalyst 6 in the flow direction of the exhaust.

[0019] In the intake passage 2, an intercooler 11 is provided upstream of the first throttle valve 4 in the flow direction of the intake air to cool the intake air compressed (pressurized) by the compressor and improve the filling efficiency.

[0020] The internal combustion engine 1 is capable of performing exhaust gas recirculation (EGR) that introduces (recirculates) a part of the exhaust gas from the exhaust passage 3 into the intake passage 2 as EGR gas, and has an EGR passage 12 as an exhaust recirculation passage that branches from the exhaust passage 3 and is connected to the intake passage 2. One end of the EGR passage 12 is connected to the exhaust passage 3 at a position between the electric heating catalyst 7 and the diesel particulate filter 8, and the other end is connected to the intake passage 2 at a position upstream of the second throttle valve 5 in the intake flow direction. An electric EGR valve 13 for adjusting (controlling) the flow rate of the EGR gas introduced into the intake passage 2 is provided in this EGR passage 12.

[0021] The EGR valve 13 is controlled by a control unit 14 that controls the internal combustion engine 1 to have a target valve opening degree.

[0022] The control unit 14 corresponds to a control section. The control unit 14 is a well-known digital computer provided with a CPU, a ROM, a RAM, and an input / output interface.

[0023] Output signals of various sensors such as a crank angle sensor 15 that detects the crank angle of the crankshaft of the internal combustion engine 1, an accelerator opening sensor 16 that detects the depression amount (accelerator opening degree) of the accelerator pedal, a first exhaust temperature sensor 17 that detects the exhaust temperature on the inlet side of the diesel particulate filter 8, and a second exhaust temperature sensor 18 that detects the exhaust temperature on the outlet side of the diesel particulate filter 8 are input to the control unit 14.

[0024] The control unit 14 calculates the engine speed of the internal combustion engine 1 from the detection signal of the crank angle sensor 15. The control unit 14 calculates the required load of the internal combustion engine 1 from the detection signal of the accelerator opening sensor 16. The control unit 14 is capable of detecting the State of Charge (SOC), which is the ratio of the remaining charge to the charge capacity of the battery. In addition, the control unit 14 calculates the temperature of the exhaust particulate filter 8 from the detection signals of the first exhaust temperature sensor 17 and the second exhaust temperature sensor 18. The temperature of the exhaust particulate filter 8 may also be detected by attaching a temperature sensor to the exhaust particulate filter 8.

[0025] The control unit 14 is capable of calculating the amount of exhaust particulate matter (PM) collected (accumulated) by the exhaust particulate matter filter 8. The amount of exhaust particulate matter (PM) collected (accumulated) by the exhaust particulate matter filter 8 is calculated, for example, from the operating history of the internal combustion engine 1. Alternatively, the amount of exhaust particulate matter (PM) collected (accumulated) by the exhaust particulate matter filter 8 may be calculated by the control unit 14 using the detection signal from a differential pressure sensor that detects the pressure difference between the inlet and outlet sides of the exhaust particulate matter filter 8.

[0026] Then, when the control unit 14 receives a request to regenerate the exhaust particulate filter 8, it motors the internal combustion engine 1 to regenerate the exhaust particulate filter 8. Motoring means stopping the fuel injection of the internal combustion engine 1 and rotating the internal combustion engine 1 with the electric motor.

[0027] The regeneration of the exhaust particulate filter 8 ends when, for example, the amount of exhaust particulate matter accumulated on the exhaust particulate filter 8 falls below a target accumulation amount, which changes according to the battery's SOC. The target accumulation amount may be set to increase as the battery SOC decreases. Alternatively, the target accumulation amount may be the amount of exhaust particulate matter accumulated on the exhaust particulate filter 8 when the battery SOC falls below a preset SOC threshold.

[0028] Here, a request for regeneration of the exhaust particulate filter 8 is generated (established) when the battery SOC of the battery is equal to or greater than a predetermined first battery SOC threshold Cp, and the amount of exhaust particulate matter collected (accumulated) by the exhaust particulate filter 8 is equal to or greater than a predetermined collection amount threshold D. The first battery SOC threshold Cp is a value greater than the second battery SOC threshold Cmin, which will be described later, and is set so, for example, that the battery SOC does not fall below the second battery SOC threshold Cmin during the regeneration of the exhaust particulate filter 8.

[0029] Then, when a request for regeneration of the exhaust particulate filter 8 arises (is fulfilled), if the temperature of the exhaust particulate filter 8 is in the high-temperature range where regeneration of the exhaust particulate filter 8 is prohibited, load reduction control is implemented to reduce the load of the operating internal combustion engine 1 by a predetermined amount, and regeneration of the exhaust particulate filter 8 is started after the temperature of the exhaust particulate filter 8 has been reduced to the temperature range in which regeneration is permitted.

[0030] In other words, when a request for regeneration of the exhaust particulate filter 8 arises while the exhaust particulate filter 8 is in a predetermined regeneration prohibition area, the vehicle actively cools the exhaust particulate filter 8 by implementing load reduction control so that the exhaust particulate filter 8 moves into a regeneration permission area.

[0031] Then, when the vehicle performs load reduction control and the temperature of the exhaust particulate filter 8 drops to a predetermined regeneration target temperature T1, the load reduction control is terminated and the internal combustion engine 1 is continued to motor to perform (start) regeneration of the exhaust particulate filter 8.

[0032] In other words, the control unit 14 performs load reduction control when the temperature of the exhaust particulate filter 8 is above a predetermined regeneration permission upper threshold that prohibits the regeneration of the exhaust particulate filter 8, the battery SOC of the battery is above the first battery SOC threshold Cp, and the amount of exhaust particulate matter collected by the exhaust particulate filter 8 is above the collection amount threshold D, and a request for regeneration of the exhaust particulate filter 8 is generated.

[0033] During regeneration, the exhaust particulate filter 8 experiences a temperature increase due to the combustion of accumulated (collected) exhaust particulate matter. In other words, the more exhaust particulate matter accumulated (collected) there is, the more likely the exhaust particulate filter 8 is to overheat during regeneration, becoming excessively hot.

[0034] Figure 2 is an explanatory diagram showing the relationship between the regeneration permission upper threshold and the regeneration target temperature T1. The characteristic line S0 in Figure 2 represents the regeneration permission upper threshold, which indicates the upper limit temperature according to the amount of exhaust particulate matter deposited, at which the exhaust particulate filter 8 will not overheat during regeneration. The regeneration permission upper threshold corresponds to the regeneration prohibition temperature at which regeneration of the exhaust particulate filter 8 is prohibited. The characteristic line S1 in Figure 2 represents the regeneration target temperature T1.

[0035] In Figure 2, the region above the characteristic line S0 is the region where the exhaust particulate filter 8 overheats and is therefore the regeneration prohibited region. In Figure 2, the region below the characteristic line S0 is the region where the exhaust particulate filter 8 does not overheat and is therefore the regeneration permitted region.

[0036] The upper limit threshold for permitted regeneration is set to increase as the amount of exhaust particulate matter accumulation decreases.

[0037] The regeneration target temperature T1 corresponds to the first temperature threshold and is a predetermined temperature lower than the regeneration permit upper limit threshold, regardless of the amount of exhaust particulate matter accumulated. The relationship with the regeneration permit upper limit threshold remains constant regardless of the amount of exhaust particulate matter accumulated (collected) in the exhaust particulate matter filter 8. In other words, characteristic line S1 is a parallel downward shift of characteristic line S0, and the distance between it and characteristic line S0 remains constant regardless of the amount of exhaust particulate matter accumulated (collected). That is, the regeneration target temperature T1 is set to change in line with the regeneration permit upper limit threshold as the amount of exhaust particulate matter accumulated changes.

[0038] Furthermore, the regeneration target temperature T1 defined by characteristic curve S1 is set to a value that provides a margin over the regeneration permit upper threshold defined by characteristic curve S0, so as to prevent the exhaust particulate filter 8 from overheating during regeneration.

[0039] In other words, the regeneration target temperature T1 is a temperature that is in line with the upper limit threshold for permitted regeneration, set to a temperature just before the regeneration of the exhaust particulate filter 8 is prohibited, and always set to a temperature close to the upper limit within the temperature range in which the regeneration of the exhaust particulate filter 8 is permitted.

[0040] Figure 3 is a timing chart showing an example of changes in various state quantities during the regeneration of the exhaust particulate filter 8. Time t1 in Figure 3 is the timing when a regeneration request for the exhaust particulate filter 8 occurs. At the timing shown in Figure 3, the amount of exhaust particulate matter accumulated in the exhaust particulate filter 8 has reached the collection threshold D. At time t1, the vehicle's battery SOC is greater than a predetermined first battery SOC threshold Cp. The first battery SOC threshold Cp is a condition necessary for a filter regeneration request for the exhaust particulate filter 8 to occur, and is a predetermined amount greater than the second battery SOC threshold Cmin. The internal combustion engine 1 starts to drive the generator and charge the battery when the battery SOC of the battery falls below the second battery SOC threshold Cmin. The battery is managed so that its battery SOC is equal to or greater than the second battery SOC threshold Cmin. The second battery SOC threshold Cmin is the lower limit of the battery SOC of the battery.

[0041] Time t2 in Figure 3 is the timing when load reduction control is initiated. In Figure 3, there is a time lag between the occurrence of a regeneration request and the start of load reduction control, but load reduction control may also be initiated at time t1, which is the timing when a regeneration request for the exhaust particulate filter 8 occurs.

[0042] Time t3 in Figure 3 is the moment when, as a result of load reduction control, the temperature of the exhaust particulate filter 8 reaches the regeneration target temperature T1. The vehicle starts motoring at time t3 and begins regeneration of the exhaust particulate filter 8. Note that T0 is the temperature corresponding to the upper limit threshold for regeneration permission when the amount of exhaust particulate matter accumulated in the exhaust particulate filter 8 is the collection threshold D. The vehicle's motoring is controlled so that the engine speed of the internal combustion engine 1 does not change before and after time t3. In other words, the engine speed of the internal combustion engine 1 when load reduction control is implemented is controlled so as not to change from the engine speed under the operating conditions of the internal combustion engine 1 immediately before the load reduction control is implemented.

[0043] In Figure 3, prior to time t3, the internal combustion engine 1 operates autonomously and generates power for the electric motor mentioned above.

[0044] Figure 4 is a schematic diagram illustrating the correlation between the amount of exhaust particulate matter collected by the exhaust particulate filter 8 and the temperature of the exhaust particulate filter 8. In the example shown in Figure 4, load reduction control is initiated when a regeneration request for the exhaust particulate filter 8 occurs.

[0045] The thick solid line characteristic curve M in Figure 4 shows an example of the change in the amount of exhaust particulate matter deposited during regeneration of the exhaust particulate filter 8 in the vehicle of the embodiment described above. The thick solid line characteristic curve Ft in Figure 4 shows the temperature change of the exhaust particulate filter 8 corresponding to characteristic curve M.

[0046] The characteristic line m, shown as a thick dashed line in Figure 4, shows an example of the change in the amount of exhaust particulate matter deposited during regeneration of the exhaust particulate filter 8 in the comparative example vehicle. The characteristic line ft, also shown as a thick dashed line in Figure 4, shows the temperature change of the exhaust particulate filter 8 corresponding to characteristic line m.

[0047] In the comparative example vehicle, if the exhaust particulate filter 8 is hot when a regeneration request is made and the exhaust particulate filter 8 is in the regeneration prohibited region, regeneration of the exhaust particulate filter 8 will not be performed until the temperature of the exhaust particulate filter 8 decreases and the state of the exhaust particulate filter 8 naturally moves to the regeneration permitted region (until time t4 in Figure 4). In other words, in the comparative example vehicle, there is a risk that regeneration cannot be performed promptly even when a regeneration request for the exhaust particulate filter 8 is made. Therefore, in the comparative example vehicle, it is necessary to consider the amount of exhaust particulate matter (accumulation) collected by the exhaust particulate filter 8 from the time a regeneration request is made until the actual regeneration of the exhaust particulate filter 8 is performed (times t1 to t4 in Figure 3), and set a larger margin (e.g., B2) in the capacity of the exhaust particulate filter 8 (e.g., Q2), which necessitates increasing the capacity Q2 of the exhaust particulate filter 8 accordingly.

[0048] On the other hand, in the vehicle of the above-described embodiment, if the temperature of the exhaust particulate filter 8 is high when a regeneration request for the exhaust particulate filter 8 occurs (time t1 in Figure 3), load reduction control is performed to lower the temperature of the exhaust particulate filter 8 (times t1-t2 in Figure 3), and regeneration of the exhaust particulate filter 8 is started promptly (time t2 in Figure 3). Time t3 in Figure 4 is the timing when the temperature of the exhaust particulate filter 8 in the vehicle of the above-described embodiment falls below the combustible temperature Tf, and regeneration of the exhaust particulate filter 8 is completed in the vehicle of the above-described embodiment. Also, time t5 in Figure 4 is the timing when the temperature of the exhaust particulate filter 8 in the comparative example vehicle falls below the combustible temperature Tf, and regeneration of the exhaust particulate filter 8 is completed in the vehicle of the comparative example.

[0049] In the vehicle of the above-described embodiment, the amount of exhaust particulate matter (accumulation) collected by the exhaust particulate matter filter 8 during the period from when a regeneration request for the exhaust particulate matter filter 8 is generated until the actual regeneration of the exhaust particulate matter filter 8 is performed (times t1 to t2 in Figure 3) can be reduced compared to the vehicle of the comparative example.

[0050] Therefore, in the vehicle of the above-described embodiment, it is possible to reduce the margin B1 in the capacity Q1 of the exhaust particulate filter 8 compared to the vehicle of the comparative example. In other words, in the vehicle of the above-described embodiment, it is possible to reduce the capacity of the exhaust particulate filter 8 compared to the vehicle of the comparative example without causing a deterioration in exhaust performance, and overall, the exhaust particulate filter 8 can be made smaller.

[0051] In other words, in the vehicle of the above embodiment, even if the temperature of the exhaust particulate filter 8 is at a high temperature that does not permit regeneration when a regeneration request for the exhaust particulate filter 8 arises, it is possible to actively control the timing of the start of regeneration of the exhaust particulate filter 8. Therefore, when a regeneration request for the exhaust particulate filter 8 arises, the regeneration process can be carried out as quickly as possible, and the capacity of the installed exhaust particulate filter 8 can be reduced without causing deterioration of exhaust performance.

[0052] In the vehicle of the above-described embodiment, the capacity of the exhaust particulate filter 8 is Q1, which is the sum of the margin B1 and the amount of exhaust particulate matter A that can be processed in one regeneration of the exhaust particulate filter 8. In the vehicle of the comparative example, the capacity of the exhaust particulate filter 8 is Q2, which is the sum of the margin B2 and the amount of exhaust particulate matter B that can be processed in one regeneration of the exhaust particulate filter 8.

[0053] In the comparative example vehicle, the amount of exhaust particulate matter that can be processed in one regeneration of the exhaust particulate filter 8 varies greatly, so the margin B2 needs to be set larger than the margin B1 in the vehicle of the embodiment described above, and overall the capacity Q2 of the exhaust particulate filter 8 is larger than the capacity Q1 of the exhaust particulate filter 8 in the vehicle of the embodiment.

[0054] Figure 5 is a flowchart showing the control flow during regeneration of the exhaust particulate filter 8 in the vehicle of the embodiment described above.

[0055] In step S1, it is determined whether the load reduction flag is "1" or "0". The load reduction flag is "1" when load reduction control is performed and "0" when load reduction control is not performed. If the load reduction flag is "0" in step S1, proceed to step S2. If the load reduction flag is "1" in step S1, proceed to step S8.

[0056] In step S2, it is determined whether or not a regeneration request for the exhaust particulate filter 8 is required. If it is determined in step S2 that a regeneration request has occurred, the process proceeds to step S3. If it is determined in step S2 that no regeneration request has occurred, the current routine is terminated.

[0057] In step S3, it is determined whether the temperature of the exhaust particulate filter 8 is below the regeneration target temperature T1. If it is determined in step S3 that the temperature of the exhaust particulate filter 8 is below the regeneration target temperature T1, the process proceeds to step S4. If it is determined in step S3 that the temperature of the exhaust particulate filter 8 is not below the regeneration target temperature T1, the process proceeds to step S5.

[0058] In step S4, the internal combustion engine 1 is motorized to regenerate the exhaust particulate filter 8. Once the regeneration of the exhaust particulate filter 8 is complete in step S4, the regeneration request for the exhaust particulate filter 8 is reset to none.

[0059] In step S5, it is determined whether the battery SOC of the above battery is equal to or greater than the first battery SOC threshold Cp. If it is determined in step S5 that the battery SOC is equal to or greater than the first battery SOC threshold Cp, the process proceeds to step S6. If it is determined in step S5 that the battery SOC is not equal to or greater than the first battery SOC threshold Cp, the process proceeds to step S7.

[0060] In step S6, load reduction control is initiated, and the load reduction flag is set to "1".

[0061] In step S7, the charging mode operation continues. That is, the internal combustion engine 1 continues the operation mode that supplies power to the battery and charges the battery.

[0062] In step S8, it is determined whether the temperature of the exhaust particulate filter 8 is below the regeneration target temperature T1. If it is determined in step S8 that the temperature of the exhaust particulate filter 8 is below the regeneration target temperature T1, the load reduction control is terminated and the process proceeds to step S9. If it is determined in step S8 that the temperature of the exhaust particulate filter 8 is not below the regeneration target temperature T1, the load reduction control is continued and the current routine is terminated.

[0063] In step S9, the motoring of the internal combustion engine 1 is performed to regenerate the exhaust particulate filter 8. Also, once the regeneration of the exhaust particulate filter 8 is completed in step S9, the regeneration request for the exhaust particulate filter 8 is reset to none. Furthermore, in step S9, the load reduction flag is reset to "0".

[0064] In step S2, if the internal combustion engine 1 is not operating at a fuel-efficient operating point, this routine may be terminated. When the internal combustion engine 1 is not operating at a fuel-efficient operating point, the vehicle is considered to be in an operating state that requires electricity. Therefore, when the internal combustion engine 1 is not operating at a fuel-efficient operating point, even if a regeneration request for the exhaust particulate filter 8 is generated, the vehicle's drivability may be prioritized.

[0065] Furthermore, in step S8, if the battery SOC of the above-mentioned battery has fallen to, for example, below the first battery SOC threshold Cp, the load reduction control may be stopped, the load reduction flag may be reset to "0", and the routine may be terminated.

[0066] Although specific embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0067] For example, the first battery SOC threshold Cp may be set to increase as the temperature of the exhaust particulate filter 8 increases. More specifically, the first battery SOC threshold Cp may be set to increase as the temperature of the exhaust particulate filter 8 increases at the time when the amount of exhaust particulate matter collected by the exhaust particulate filter 8 exceeds the collection amount threshold D.

[0068] The above-described embodiment relates to a control method for a hybrid vehicle and a control device for a hybrid vehicle. [Explanation of Symbols]

[0069] 1…Internal combustion engine 2…Intake passage 3… Exhaust passage 4…First throttle valve 5…Second throttle valve 6…First exhaust gas purification catalyst 7…Electric heating catalyst 8… Exhaust particulate filter 9…Second exhaust gas purification catalyst 10... Turbocharger 11…Intercooler 12...EGR passage 13…EGR valve 14…Control Unit 15... Crank angle sensor 16…Accelerator position sensor 17…First exhaust temperature sensor 18…Second exhaust temperature sensor

Claims

1. A control method for a hybrid vehicle comprising an internal combustion engine capable of motorization by an electric motor, and an exhaust particulate filter positioned in the exhaust passage to collect exhaust particulate matter in the exhaust, wherein the exhaust particulate filter is regenerated during the motorization, A control method for a hybrid vehicle, characterized in that when the temperature of the exhaust particulate filter is above a predetermined regeneration prohibition temperature at which regeneration of the exhaust particulate filter is prohibited, the battery SOC of the onboard battery is above a predetermined first battery SOC threshold, and the amount of exhaust particulate matter collected by the exhaust particulate filter is above a predetermined collection amount threshold, a regeneration request for the exhaust particulate filter is generated, load reduction control is performed to reduce the load of the internal combustion engine by a predetermined amount to cool the exhaust particulate filter.

2. The above load reduction control terminates when the temperature of the exhaust particulate filter reaches a predetermined first temperature threshold at which regeneration of the exhaust particulate filter is permitted. The control method for a hybrid vehicle according to claim 1, characterized in that when the above load reduction control is completed, the above motoring is started and the regeneration of the exhaust particulate filter is started.

3. The control method for a hybrid vehicle according to claim 1, characterized in that the engine speed of the internal combustion engine when implementing the load reduction control described above is not changed from the engine speed of the internal combustion engine under the operating conditions immediately before implementing the load reduction control described above.

4. The control method for a hybrid vehicle according to claim 1, characterized in that the first battery SOC threshold is set to increase as the temperature of the exhaust particulate filter increases.

5. An internal combustion engine that can be motorized by an electric motor, An exhaust particulate filter is placed in the exhaust passage to capture exhaust particulate matter in the exhaust, The system includes a control unit that performs regeneration of the exhaust particulate filter during the motoring process, The control unit described above is characterized in that, when the temperature of the exhaust particulate filter is above a predetermined regeneration prohibition temperature at which regeneration of the exhaust particulate filter is prohibited, the battery SOC of the on-board battery is above a predetermined first battery SOC threshold, and the amount of exhaust particulate matter collected by the exhaust particulate filter is above a predetermined collection amount threshold, and a request for regeneration of the exhaust particulate filter is generated, the control unit performs load reduction control to reduce the load of the internal combustion engine by a predetermined amount, thereby cooling the exhaust particulate filter.

Images