Vehicle control system

Abstract

To provide a vehicle control device capable of enhancing regeneration of a filter while reducing an exhaust amount of NOx.SOLUTION: A control device of a vehicle which comprises a gasoline engine, a throttle valve, an injector, and a GPF which collects particulate matters included in exhaust gas discharged from the gasoline engine has: a control section which controls an opening of the throttle valve; a fuel cut processing section which executes fuel cut processing when a predetermined fuel cut condition is met; and a filter regeneration processing section which executes filter regeneration processing when a predetermined filter regeneration condition is met. When the predetermined fuel cut condition is met in addition to the predetermined filter regeneration condition, the control section controls the opening of the throttle valve in a manner that makes the same larger than the opening when only the fuel cut processing is executed.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a technique for controlling an internal combustion engine including a plurality of cylinders and a filter that collects particulate matter in an exhaust passage of the internal combustion engine. Before stopping the internal combustion engine, fuel supply is stopped in some cylinders, and combustion is continued by supplying fuel in other cylinders, thereby supplying oxygen to the filter to perform regeneration of the filter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1 above, oxygen in the exhaust gas is supplied to the three-way catalyst, and there is a risk that the purification rate of nitrogen oxides (hereinafter referred to as "NOx") in the three-way catalyst may decrease.

[0005] As described above, in the technique described in Patent Document 1, combustion is continued in some cylinders while the purification rate of the three-way catalyst decreases during regeneration of the filter, so there is a risk that the NOx emission amount cannot be reduced.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for a vehicle that can promote regeneration of a filter while reducing the NOx emission amount.

Means for Solving the Problems

[0007] To achieve the above objective, the present invention provides a vehicle control device comprising: a gasoline engine; a throttle valve disposed in the intake passage of the gasoline engine; a fuel supply device that supplies fuel to the gasoline engine; and a filter disposed in the exhaust passage of the gasoline engine that collects particulate matter contained in the exhaust gas discharged from the gasoline engine, wherein the control device comprises: a control unit that controls the opening degree of the throttle valve; a fuel cut processing unit that performs a fuel cut processing to stop the fuel supply to the gasoline engine when predetermined fuel cut conditions are met; and a filter regeneration processing unit that performs a filter regeneration processing to oxidize particulate matter accumulated on the filter when predetermined filter regeneration conditions are met, wherein the control unit performs a filter regeneration processing to oxidize particulate matter accumulated on the filter when predetermined fuel cut conditions are met in addition to the predetermined filter regeneration conditions. Ta In that case, The fuel supply to the gasoline engine is stopped, and during the suspension of said fuel supply The configuration includes a mechanism that controls the opening of the throttle valve to a larger opening than the opening of the throttle valve when only the fuel cut-off process is being performed. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a vehicle control device that can reduce NOx emissions while promoting filter regeneration. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of a vehicle equipped with a vehicle control device according to a first embodiment of the present invention. [Figure 2] Figure 2 is a flowchart showing the processing flow of GPF regeneration control performed by the vehicle control device according to the first embodiment of the present invention. [Figure 3] Figure 3 is a graph showing the GPF regeneration rate in a vehicle equipped with a vehicle control device according to the first embodiment of the present invention. [Figure 4] Figure 4 is a map of the maximum oxygen supply amount referenced by the vehicle control device according to a second embodiment of the present invention. [Figure 5]Figure 5 is a flowchart showing the processing flow of GPF regeneration control performed by the vehicle control device according to the second embodiment of the present invention. [Modes for carrying out the invention]

[0010] A vehicle control device according to one embodiment of the present invention is a vehicle control device comprising a gasoline engine, a throttle valve disposed in the intake passage of the gasoline engine, a fuel supply device that supplies fuel to the gasoline engine, and a filter disposed in the exhaust passage of the gasoline engine that collects particulate matter contained in the exhaust gas discharged from the gasoline engine, comprising a control unit that controls the opening degree of the throttle valve, a fuel cut processing unit that performs a fuel cut processing that stops the supply of fuel to the gasoline engine when predetermined fuel cut conditions are met, and a filter regeneration processing unit that performs a filter regeneration processing that oxidizes particulate matter accumulated on the filter when predetermined filter regeneration conditions are met, wherein the control unit controls the opening degree of the throttle valve to a larger opening degree than the opening degree of the throttle valve when only the fuel cut processing is performed when predetermined fuel cut conditions are met in addition to the predetermined filter regeneration conditions. As a result, the vehicle control device according to one embodiment of the present invention can promote filter regeneration while reducing NOx emissions. [Examples]

[0011] Hereinafter, a vehicle equipped with a vehicle control device according to one embodiment of the present invention will be described with reference to the drawings.

[0012] (First example) As shown in Figure 1, the vehicle 1 of this embodiment is composed of a gasoline engine 2, an intake pipe 3, an exhaust pipe 4, and an ECU (Electronic Control Unit) 10.

[0013] The gasoline engine 2 is a so-called four-cycle engine that performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston reciprocates twice in a cylinder (not shown). The gasoline engine 2 is configured as a drive source for the vehicle 1.

[0014] The gasoline engine 2 is provided with an injector 21 as a fuel supply device for supplying fuel to the gasoline engine 2. The injector 21 is constituted by, for example, a port injection type fuel injection valve or an in-cylinder injection type fuel injection valve.

[0015] In addition to the injector 21, the gasoline engine 2 is provided with a spark plug (not shown), intake valves, exhaust valves, etc.

[0016] The intake pipe 3 is connected to the gasoline engine 2, and an intake passage 3a is formed inside. A throttle valve 31 is disposed in the intake passage 3a. The throttle valve 31 is electrically connected to the ECU 10, and the opening degree (hereinafter referred to as "throttle opening degree") is controlled according to a command signal from the ECU 10 to adjust the intake air amount to the gasoline engine 2.

[0017] The exhaust pipe 4 is connected to the gasoline engine 2, and an exhaust passage 4a is formed inside. In the exhaust passage 4a, a catalyst 41 and a GPF (Gasoline Particulate Filter) 42 as a filter are disposed in order from the upstream side in the exhaust gas flow direction of the exhaust gas.

[0018] The catalyst 41 is a three-way catalyst for purifying exhaust gas. The GPF 42 is adapted to collect particulate matter such as soot contained in the exhaust gas discharged from the gasoline engine 2.

[0019] The ECU 10 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data and the like, an input port, and an output port.

[0020] In the ROM of the computer unit, a program for causing the computer unit to function as the ECU 10 is stored together with various constants, various maps, and the like. That is, when the CPU executes the program stored in the ROM using the RAM as a work area, the computer unit functions as the ECU 10 in the present embodiment.

[0021] Various sensors such as a crank angle sensor 11, an accelerator opening sensor 12, a vehicle speed sensor 13, a temperature sensor 14, and a differential pressure sensor 15 are connected to the ECU 10.

[0022] The crank angle sensor 11 detects the rotation angle of a crankshaft (hereinafter referred to as "crank angle") of the gasoline engine 2, which is not shown. The ECU 10 calculates the engine speed, which is the rotational speed of the gasoline engine 2, based on the information indicating the crank angle input from the crank angle sensor 11.

[0023] The accelerator opening sensor 12 detects the opening of an accelerator pedal (hereinafter referred to as "accelerator opening"), which is not shown. The vehicle speed sensor 13 detects the vehicle speed, which is the speed of the vehicle 1. The temperature sensor 14 detects the filter temperature, which is the temperature of the GPF 42.

[0024] In the present embodiment, an example in which the temperature sensor 14 is provided will be described, but the temperature sensor 14 may not be equipped. In this case, the ECU 10 may estimate the filter temperature based on the engine speed and the load factor.

[0025] The differential pressure sensor 15 detects the differential pressure before and after the GPF 42, that is, the pressure difference between the upstream side and the downstream side in the exhaust direction across the GPF 42.

[0026] The ECU10 estimates the amount of particulate matter deposited in the GPF42 by referring to a deposit amount map based on the differential pressure across the GPF42 detected by the differential pressure sensor 15. The deposit amount map is a map that was experimentally determined in advance, showing the relationship between the differential pressure across the GPF42, i.e., the pressure loss in the GPF42 due to the deposition of particulate matter, and the amount of particulate matter deposited, and is stored in the ROM of the ECU10.

[0027] The ECU 10 functions as a fuel cut processing unit 101 that, when predetermined fuel cut conditions are met, stops the fuel supply to the gasoline engine 2 by the injector 21, and resumes fuel supply to the gasoline engine 2 when predetermined fuel cut return conditions are met while the fuel supply is stopped.

[0028] The predetermined fuel cut conditions include, for example, the accelerator opening being "0" and vehicle 1 decelerating. The predetermined fuel cut return conditions include, for example, the engine speed decreasing to a predetermined return speed, or the accelerator pedal being pressed down.

[0029] ECU10 functions as a filter regeneration processing unit 102 that performs filter regeneration processing to oxidize particulate matter deposited on GPF42 when predetermined filter regeneration conditions are met. In this embodiment, the predetermined filter regeneration condition is that the amount of particulate matter deposited exceeds the regeneration control threshold, as estimated above. The regeneration control threshold is the upper limit of the amount of particulate matter deposited at which it can be determined that regeneration of GPF42 is not necessary, and is determined experimentally in advance and stored in the ROM of ECU10.

[0030] In the filter regeneration process, in order to oxidize the particulate matter deposited on the GPF42, for example, ignition retardation control or lean operation is performed in the gasoline engine 2. The filter regeneration process is not limited to the method described above, but other known filter regeneration methods may also be applied.

[0031] Furthermore, the ECU 10 functions as a control unit 103 that controls the throttle valve 31. For example, the ECU 10 adjusts the throttle opening based on the required torque calculated according to the accelerator opening, etc.

[0032] When the predetermined fuel cut-off conditions are met in addition to the predetermined filter regeneration conditions, the ECU10 controls the throttle opening to a larger opening than the throttle opening when only the fuel cut-off process is performed.

[0033] In this case, it is preferable that the ECU 10 has a period during which the throttle opening is 100%, i.e., the throttle valve 31 is fully open, when performing the filter regeneration process and the fuel cut process. In this embodiment, the ECU 10 controls the throttle valve 31 to be fully open when a predetermined fuel cut condition is met in addition to a predetermined filter regeneration condition, that is, when performing the filter regeneration process and the fuel cut process.

[0034] Next, referring to Figure 2, the processing flow of the GPF regeneration control performed by the ECU 10 in this embodiment will be described. The GPF regeneration control is performed repeatedly at predetermined time intervals.

[0035] As shown in Figure 2, ECU10 estimates the amount of particulate matter deposited in GPF42 (step S1).

[0036] The ECU10 determines whether the amount of particulate matter accumulated, estimated in step S1, exceeds the regeneration control threshold (step S2). If the ECU10 determines in step S2 that the amount of particulate matter accumulated does not exceed the regeneration control threshold, it terminates this GPF regeneration control.

[0037] If the ECU 10 determines in step S2 that the amount of particulate matter deposited exceeds the regeneration control threshold, it starts the filter regeneration process (step S3).

[0038] Next, the ECU 10 determines whether or not there is a fuel cut request, that is, whether or not the predetermined fuel cut conditions have been met (step S4). If the ECU 10 determines in step S4 that there is no fuel cut request, it returns to step S3.

[0039] If the ECU10 determines in step S4 that there is a fuel cut request, it performs a fuel cut operation (step S5).

[0040] Next, the ECU 10 controls the throttle valve 31 to open fully (step S6). This increases the amount of oxygen supplied to the GPF 42 when the filter regeneration process and fuel cut process are being performed simultaneously, thereby promoting the oxidation of particulate matter deposited on the GPF 42.

[0041] Subsequently, while the filter regeneration process and fuel cut process are being performed, the ECU 10 determines whether or not there is a request for fuel restoration, that is, whether or not the predetermined fuel cut restoration conditions have been met (step S7). If the ECU 10 determines in step S7 that there is no request for fuel restoration, it returns to step S6.

[0042] If the ECU 10 determines in step S7 that there is a request for fuel restoration, it controls the throttle valve 31 so that the throttle opening corresponds to the requested torque calculated according to the driver's requested torque, i.e., the accelerator pedal opening (step S8).

[0043] Next, the ECU 10 resumes fuel supply to the gasoline engine 2 (step S9) and terminates this GPF regeneration control.

[0044] As described above, the vehicle control device according to this embodiment is configured to control the throttle opening to a larger opening (for example, fully open) than the throttle opening when only the fuel cut process is performed, when a predetermined fuel cut condition is met in addition to a predetermined filter regeneration condition.

[0045] With this configuration, the control device of the vehicle according to this embodiment can increase the amount of oxygen supplied to the GPF42 when performing filter regeneration processing and fuel cut-off processing.

[0046] Here, the amount of particulate matter such as soot that can be oxidized is determined by the amount of oxygen supplied to the GPF42 and the temperature.

[0047] Figure 3 compares the GPF regeneration rate between this embodiment (shown by a dotted line in Figure 3), in which the throttle valve 31 is fully open during the filter regeneration process and fuel cut process, and a comparative example (shown by a solid line in Figure 3), in which the throttle valve is fully closed.

[0048] As shown in Figure 3, in this embodiment, the amount of oxygen supplied to GPF42 (shown by the dotted line in Figure 3) is greater than in the comparative example (shown by the solid line in Figure 3), and therefore the GPF regeneration rate is also greater than in the comparative example.

[0049] Therefore, the vehicle control device according to this embodiment can efficiently regenerate the GPF42 when performing filter regeneration processing and fuel cut-off processing.

[0050] Furthermore, the vehicle control device according to this embodiment increases the oxygen supply to the GPF42 only when the filter regeneration process and fuel cut process are performed simultaneously, thus preventing the deterioration of exhaust gas. In other words, since combustion in each cylinder is stopped by the fuel cut process, exhaust gas is no longer emitted, and exhaust gas and oxygen are not supplied together to the catalyst 41 and GPF42. Therefore, NOx contained in the exhaust gas is not discharged outside the vehicle without being purified by the catalyst 41.

[0051] Therefore, the vehicle control device according to this embodiment can reduce NOx emissions while promoting the regeneration of GPF42.

[0052] Furthermore, the vehicle control device according to this embodiment has a period during which the throttle valve 31 is fully open when performing filter regeneration processing and fuel cut processing, so that more oxygen can be supplied to the GPF 42 and the oxidation of particulate matter can be promoted.

[0053] Furthermore, the vehicle control device according to this embodiment is configured to restart fuel supply to the gasoline engine 2 by controlling the throttle valve 31 to a throttle opening corresponding to the torque requested by the driver when predetermined fuel cut-off return conditions are met while the filter regeneration process and fuel cut-off process are being performed.

[0054] With this configuration, the vehicle control device according to this embodiment can perform filter regeneration processing of the GPF42 without impairing the drivability of the vehicle 1.

[0055] (Second example) Next, a second embodiment will be described with reference to Figures 4 and 5.

[0056] The vehicle control device according to this embodiment differs from the vehicle control device according to the first embodiment in its method of controlling the throttle opening when performing filter regeneration processing and fuel cut processing, but other components are the same as those of the first embodiment. Therefore, in the following description, components identical to those of the first embodiment will be denoted by the same reference numerals as those of the first embodiment, and their descriptions will be omitted.

[0057] In this embodiment, when the ECU 10 performs filter regeneration processing and fuel cut processing, it controls the opening degree of the throttle valve 31 based on the filter temperature, which indicates the temperature of the GPF 42, and the amount of particulate matter deposited on the GPF 42.

[0058] Specifically, when the ECU 10 performs filter regeneration and fuel cut-off processing, it determines the oxygen supply amount by referring to the maximum oxygen supply amount map based on the filter temperature before filter regeneration processing detected by the temperature sensor 14 (hereinafter referred to as "initial filter temperature") and the amount of particulate matter deposited, which is estimated by referring to the deposit amount map based on the differential pressure across the GPF 42, and controls the opening degree of the throttle valve 31 to achieve the determined oxygen supply amount.

[0059] The maximum oxygen supply map is a map that determines the maximum oxygen supply amount that promotes oxidation of particulate matter and maximizes the regeneration efficiency of the GPF42 while the filter temperature does not reach the limit temperature during filter regeneration processing. In other words, it determines the maximum oxygen supply amount that keeps the filter temperature within the allowable temperature range during filter regeneration processing. This map is determined experimentally in advance and stored in the ROM of the ECU10.

[0060] As shown in Figure 4, in the maximum oxygen supply map, the initial filter temperature is shown on the vertical axis, and the oxygen supply is defined to increase as the initial filter temperature increases. This is because particulate matter is more easily oxidized as the initial filter temperature increases.

[0061] In Figure 4, "Small" indicates a low oxygen supply, and "Large" indicates a high oxygen supply. "Medium" indicates an oxygen supply that is higher than "Small" but lower than "Large".

[0062] Furthermore, in the maximum oxygen supply map, the horizontal axis shows the amount of particulate matter deposited, and the oxygen supply is defined to increase as the amount of particulate matter deposited increases. This is because as the amount of particulate matter deposited increases, it becomes necessary to increase the oxidation rate of the particulate matter.

[0063] However, in the maximum oxygen supply map, in areas where the filter temperature may exceed the allowable temperature due to filter regeneration (areas labeled "Regeneration prohibited" in Figure 4), the throttle valve 31 is defined to be controlled to be fully closed in order to protect the GPF42.

[0064] Next, referring to Figure 5, the processing flow of the GPF regeneration control performed by the ECU 10 in this embodiment will be described. The GPF regeneration control is performed repeatedly at predetermined time intervals.

[0065] As shown in Figure 5, the ECU10 estimates the amount of particulate matter deposited in GPF42 (step S11).

[0066] The ECU10 determines whether the amount of particulate matter accumulated, estimated in step S11, exceeds the regeneration control threshold (step S12). If the ECU10 determines in step S12 that the amount of particulate matter accumulated does not exceed the regeneration control threshold, it terminates this GPF regeneration control.

[0067] If the ECU 10 determines in step S12 that the amount of particulate matter deposited exceeds the regeneration control threshold, it starts the filter regeneration process (step S13).

[0068] Next, the ECU 10 determines whether or not there is a fuel cut request, that is, whether or not a predetermined fuel cut condition has been met (step S14). If the ECU 10 determines in step S14 that there is no fuel cut request, it terminates this GPF regeneration control.

[0069] If the ECU 10 determines in step S14 that there is a fuel cut request, it acquires the filter temperature detected by the temperature sensor 14 as the initial filter temperature before starting the filter regeneration process (step S15).

[0070] Next, the ECU 10 determines the oxygen supply amount from the maximum oxygen supply map based on the amount of particulate matter deposited estimated in step S11 and the initial filter temperature obtained in step S15 (step S16).

[0071] Subsequently, ECU10 performs a fuel cut-off procedure (step S17).

[0072] Next, the ECU 10 controls the throttle valve 31 to achieve a throttle opening corresponding to the oxygen supply amount determined in step S16 (step S18). As a result, when filter regeneration and fuel cut-off processes are performed simultaneously, the amount of oxygen supplied to the GPF 42 increases, promoting the oxidation of particulate matter deposited on the GPF 42.

[0073] Subsequently, while the filter regeneration process and fuel cut process are being performed, the ECU 10 determines whether or not there is a request for fuel restoration, that is, whether or not the predetermined fuel cut restoration conditions have been met (step S19). If the ECU 10 determines in step S19 that there is no request for fuel restoration, it returns to step S18.

[0074] If the ECU 10 determines in step S19 that there is a request for fuel restoration, it controls the throttle valve 31 so that the throttle opening corresponds to the requested torque calculated according to the driver's requested torque, i.e., the accelerator pedal opening (step S20).

[0075] Next, the ECU 10 resumes fuel supply to the gasoline engine 2 (step S21) and terminates this GPF regeneration control.

[0076] As described above, the vehicle control device according to this embodiment has the following effects in addition to the effects described in the first embodiment.

[0077] In other words, the vehicle control device according to this embodiment controls the opening degree of the throttle valve 31 based on the filter temperature and the amount of particulate matter deposited on the GPF42 when performing filter regeneration processing and fuel cut processing. This prevents overheating of the GPF42 and allows the amount of oxygen supplied to the GPF42 to be adjusted to an appropriate amount according to the amount of particulate matter deposited.

[0078] While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims. [Explanation of Symbols]

[0079] 1 vehicle 2 Gasoline engine 3. Intake pipe 3a Intake passage 4 Exhaust pipes 4a Exhaust passage 10 ECU 11. Crank angle sensor 12. Accelerator position sensor 13. Vehicle speed sensor 14. Temperature sensor 15 Differential pressure sensor 21. Injector (fuel supply device) 31 Throttle valve 41 Catalyst 42 GPF (Filter) 101 Fuel cut-off section 102 Filter Regeneration Processing Unit 103 Control Unit

Claims

1. Gasoline engine, A throttle valve located in the intake passage of the aforementioned gasoline engine, A fuel supply device that supplies fuel to the aforementioned gasoline engine, A filter is placed in the exhaust passage of the gasoline engine and collects particulate matter contained in the exhaust gas discharged from the gasoline engine, A vehicle control device equipped with, A control unit that controls the opening degree of the throttle valve, A fuel cut processing unit performs a fuel cut operation that stops the supply of fuel to the gasoline engine when predetermined fuel cut conditions are met, The system includes a filter regeneration processing unit that performs a filter regeneration process to oxidize particulate matter accumulated on the filter when predetermined filter regeneration conditions are met, A vehicle control device characterized in that, when the predetermined fuel cut-off condition is met in addition to the predetermined filter regeneration condition, the control unit stops the fuel supply to the gasoline engine and controls the opening of the throttle valve during the suspension of fuel supply to be greater than the opening of the throttle valve when only the fuel cut-off process is being performed.

2. The control unit, when the predetermined fuel cut-off condition is met in addition to the predetermined filter regeneration condition, stops the fuel supply to the gasoline engine and controls the opening of the throttle valve to fully open during the suspension of the fuel supply, as described in claim 1.

3. The control unit, when the predetermined fuel cut-off condition is met in addition to the predetermined filter regeneration condition, stops the fuel supply to the gasoline engine, and controls the opening degree of the throttle valve during the suspension of the fuel supply to be larger as the filter temperature, which indicates the temperature of the filter, is higher, or as the amount of particulate matter deposited on the filter increases, as described in claim 1.

4. If, in addition to the predetermined filter regeneration conditions, the predetermined fuel cut-off conditions are met and the fuel supply to the gasoline engine is stopped, and then the predetermined fuel cut-off return conditions are met, The control unit controls the throttle valve to an opening degree corresponding to the torque requested by the driver. The vehicle control device according to any one of claims 1 to 3, characterized in that the fuel cut-off processing unit resumes fuel supply to the gasoline engine.

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