JP7800512B2 - vehicle - Google Patents

Description

This disclosure relates to vehicles.

Conventionally, a vehicle of this type has been proposed that is equipped with an engine with a filter attached to the exhaust system that captures particulate matter. When a fuel cut condition is met, a fuel cut process is executed to stop fuel injection from the fuel injection valve, and the fuel cut process is stopped if the cumulative amount of intake air exceeds a predetermined value while the fuel cut process is being executed (see, for example, Patent Document 1). In this vehicle, by executing the fuel cut process, oxygen is supplied to the filter, burning the particulate matter that has accumulated on the filter and regenerating the filter. Furthermore, by stopping the fuel cut process, the filter is prevented from overheating due to the burning of a large amount of particulate matter.

Japanese Patent Application Laid-Open No. 2022-165564

In such vehicles, if the amount of particulate matter accumulated on the filter is too small, the filter's ability to capture particulate matter decreases. Therefore, when the amount of particulate matter accumulated is below a predetermined amount and the filter temperature is above a predetermined temperature (when the particulate matter is within a temperature range that allows it to be used as fuel), engine fuel cut-off is prohibited. Meanwhile, in manual transmission vehicles equipped with a manual transmission that transmits power from the engine to the drive wheels by changing gears in response to the driver's shift operation, and a clutch that can disconnect the engine from the manual transmission in response to the driver's clutch pedal operation, when changing gears in the manual transmission, the clutch is basically released when the clutch pedal is depressed, the gear is changed in response to the shift operation, and the clutch returns to an engaged state via a slip engagement state as the clutch pedal is gradually released. If engine fuel cut-off is prohibited at this time, there is a concern that the engine will rev up and drivability will deteriorate.

The primary purpose of the vehicle disclosed herein is to prevent deterioration of drivability.

The vehicle disclosed herein employs the following measures to achieve the above-mentioned primary objective.

The vehicle of the present disclosure includes:
A vehicle comprising: an engine having an exhaust system equipped with a filter that captures particulate matter; a manual transmission that transmits power from the engine to drive wheels while changing gears in response to a driver's shift operation; a clutch that can disconnect the engine from the manual transmission in response to a driver's operation of a clutch pedal; and a control device that prohibits fuel cut-off of the engine when an amount of accumulated particulate matter is less than a predetermined amount and the temperature of the filter is equal to or higher than a first predetermined temperature,
the control device permits the fuel cut when the gear position is changed even when the amount of accumulated particulate matter is less than the predetermined amount and the temperature of the filter is equal to or higher than the first predetermined temperature.
The gist of this is as follows.

In the vehicle disclosed herein, engine fuel cut-off is generally prohibited when the amount of particulate matter accumulation is less than a predetermined amount and the filter temperature is equal to or greater than a first predetermined temperature. However, even when the amount of particulate matter accumulation is less than a predetermined amount and the filter temperature is equal to or greater than the first predetermined temperature, fuel cut-off is permitted when changing gears. This prevents engine revving when changing gears in the manual transmission and reduces deterioration of drivability. Here, when changing gears in the manual transmission, it may be the period from when the clutch is turned off, the gear is changed, and until the clutch is turned on, or it may be the period from when the gear change begins to when the change is completed.

In the vehicle disclosed herein, the control device may prohibit the fuel cut when the temperature of the filter is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, regardless of whether the gear position is being changed. This makes it possible to prevent the filter from overheating due to the execution of a fuel cut to the engine.

1 is a schematic configuration diagram of a vehicle 20 according to an embodiment of the present disclosure. 2 is a schematic diagram of an engine 22 mounted on a vehicle 20. FIG. 4 is a flowchart showing an example of a permission/prohibition determination routine executed by an electronic control unit 50.

Embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a vehicle 20 according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram of an engine 22 mounted on the vehicle 20. The vehicle 20 according to the embodiment is configured as a manual transmission vehicle (MT vehicle), and as shown in FIG. 1, includes an engine 22, a manual transmission 30, a clutch 40, and an electronic control unit 50.

The engine 22 is a multi-cylinder internal combustion engine that uses fuel such as gasoline or diesel oil and outputs power through four cycles: intake, compression, expansion (explosive combustion), and exhaust. As shown in FIG. 2 , the engine 22 has a port injection valve 126 that injects fuel into the intake port and an in-cylinder injection valve 127 that injects fuel into the cylinder. It operates in one of three modes: port injection mode, in-cylinder injection mode, and combined injection mode. In port injection mode, air cleaned by the air cleaner 122 is drawn into the intake pipe 123 and passes through the throttle valve 124 and surge tank 125. Fuel is injected from the port injection valve 126 downstream of the surge tank 125 into the intake pipe 123, mixing the air and fuel. This mixture is drawn into the combustion chamber 129 via the intake valve 128 and explosively combusted by an electric spark generated by the spark plug 130. The reciprocating motion of the piston 132, which is pushed down within the cylinder bore by the resulting energy, is converted into rotational motion of the crankshaft 23. In the in-cylinder injection mode, air is drawn into the combustion chamber 129, as in the port injection mode, and fuel is injected from the in-cylinder injection valve 127 during the intake stroke or compression stroke. The fuel is then explosively combusted by an electric spark from the spark plug 130, causing rotational motion of the crankshaft 23. In the combined injection mode, fuel is injected from the port injection valve 126 when air is drawn into the combustion chamber 129, and fuel is also injected from the in-cylinder injection valve 127 during the intake stroke or compression stroke. The fuel is then explosively combusted by an electric spark from the spark plug 130, causing rotational motion of the crankshaft 23. Exhaust gas discharged from the combustion chamber 129 into an exhaust pipe 134 via an exhaust valve 133 is then discharged into the outside air via a purification device 135 and a PM filter 136. The purification device 135 has a purification catalyst (three-way catalyst) 135a that purifies harmful components in the exhaust, such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). The PM filter 136 is formed as a porous filter using ceramics, stainless steel, or the like, and captures particulate matter (PM) such as soot in the exhaust gas. Note that instead of the PM filter 136, a four-way catalyst may be used that combines the purification function of a three-way catalyst with the function of capturing particulate matter.

The manual transmission 30 is configured as a six-speed transmission, and as shown in FIG. 1, its input shaft is connected to the crankshaft 23 of the engine 22 via the clutch 40, and its output shaft is connected to a drive shaft DS that is connected to the drive wheels DW via a differential gear DG. Depending on the driver's operation of the shift lever 32, the manual transmission 30 establishes forward gears (1st through 6th speeds) and reverse gears, or disconnects the input shaft from the output shaft.

The clutch 40 is located between the engine 22 and the input shaft of the manual transmission 30. When the clutch pedal 42 is not depressed by the driver, the clutch is in an engaged state. When the clutch pedal 42 is depressed, the clutch is in a slip-engaged state or a released state depending on the amount of depression of the pedal.

The electronic control unit 50 includes a microcomputer with a CPU, ROM, RAM, flash memory, input/output ports, and communication ports. As shown in Figures 1 and 2, the electronic control unit 50 receives signals from various sensors via the input ports.

Signals input to the electronic control unit 50 include, for example, signals required to control the operation of the engine 22. Examples of signals required to control the operation of the engine 22 include the crank angle θcr from the crank position sensor 140, which detects the rotational position of the crankshaft 23 of the engine 22, and the coolant temperature Tw from the water temperature sensor 142, which detects the temperature of the coolant for the engine 22. Other examples include cam angles θci and θco from the cam position sensor 144, which detects the rotational position of the intake camshaft that opens and closes the intake valve 128 and the rotational position of the exhaust camshaft that opens and closes the exhaust valve 133. Other examples include the throttle opening TH from the throttle valve position sensor 124a that detects the position of the throttle valve 124, the intake air volume Qa from the air flow meter 123a attached upstream of the throttle valve 124 in the intake pipe 123, the intake air temperature Ta from the temperature sensor 123t attached upstream of the throttle valve 124 in the intake pipe 123, and the surge pressure Ps from the pressure sensor 125a attached to the surge tank 125. Other examples include the front air-fuel ratio AF1 from the front air-fuel ratio sensor 137 attached upstream of the purifier 135 in the exhaust pipe 134, the rear air-fuel ratio AF2 from the rear air-fuel ratio sensor 138 attached between the purifier 135 and the PM filter 136 in the exhaust pipe 134, and the differential pressure ΔP from the differential pressure sensor 136a that detects the differential pressure between the upstream and downstream sides of the PM filter 136.

Furthermore, signals input to the electronic control unit 50 include an ignition signal from an ignition switch 51, an accelerator opening Acc from an accelerator pedal position sensor 54 that detects the amount of depression of the accelerator pedal 53, a brake pedal position BP from a brake pedal position sensor 56 that detects the amount of depression of the brake pedal 55, and a vehicle speed V from a vehicle speed sensor 58.

The electronic control unit 50 outputs various control signals for controlling the operation of the engine 22 via an output port. Examples of signals output by the electronic control unit 50 include a control signal to the throttle valve 124, a control signal to the port injection valve 126, a control signal to the in-cylinder injection valve 127, and a control signal to the spark plug 130.

The electronic control unit 50 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the engine 22 from the crank position sensor 140. The engine ECU 24 also calculates the load factor KL (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 22) based on the intake air volume Qa from the air flow meter 123a and the rotation speed Ne of the engine 22. The engine ECU 24 also calculates the PM accumulation amount Qpm, which is the amount of particulate matter accumulated on the PM filter 136, based on the differential pressure ΔP from the differential pressure sensor 136a, and calculates the filter temperature tf, which is the temperature of the PM filter 136, based on the rotation speed Ne of the engine 22 and the load factor KL.

In the vehicle 20 of this embodiment, the electronic control unit 50 sets the target load rate KL* of the engine 22 based on the accelerator pedal position Acc, and performs operation control of the engine 22 (intake air volume control, fuel injection control, ignition control, etc.) so that the engine 22 operates based on the target load rate KL*.

In addition, in the vehicle 20 of this embodiment, the electronic control unit 50 cuts fuel to the engine 22 when the accelerator is released. When the filter temperature Tf is equal to or higher than the threshold value Tfref, air (oxygen) is supplied to the PM filter 136 by cutting fuel to the engine 22, and the particulate matter accumulated on the PM filter 136 reacts with the oxygen, burning the particulate matter and regenerating the PM filter 136. Here, the threshold value Tfref is the lower limit of the temperature range at which the PM filter 136 can be regenerated (particulate matter can be burned).

Next, the operation of the vehicle 20 according to this embodiment, particularly the process for determining whether or not to allow fuel cutoff for the engine 22, will be described. Figure 3 is a flowchart showing an example of a permission/prohibition determination routine executed by the electronic control unit 50. This routine is executed repeatedly.

When the permission determination routine of FIG. 3 is executed, the electronic control unit 50 first determines whether the filter temperature Tf is equal to or higher than the overheat temperature Tfot, which is higher than the threshold value Tfref (step S100). Here, the overheat temperature Tfot is defined as the temperature used to determine whether the PM filter 136 is likely to overheat due to the execution of a fuel cut of the engine 22. The overheat temperature Tfot may be a constant value, or may be set to a lower value as the PM accumulation amount Qpm increases. The latter is because when a fuel cut of the engine 22 is executed, the greater the PM accumulation amount Qpm, the greater the amount of heat generated by the combustion of particulate matter, and the more likely the filter temperature Tf is to become high.

If it is determined in step S100 that the filter temperature Tf is less than the overheat temperature Tfot, it is determined that the possibility of the PM filter 136 overheating is sufficiently low even if fuel is cut off to the engine 22, and it is determined whether the PM accumulation amount Qpm is less than the threshold value Qpmref (step S110) and whether the filter temperature Tf is equal to or greater than the threshold value Tfref (step S120). If the PM accumulation amount Qpm is too small, the particulate matter capture rate by the PM filter 136 decreases. The threshold values Qpmref and Tfref are used to determine whether particulate matter is likely to be burned and the PM accumulation amount Qpm become too small when fuel is cut off to the engine 22.

If it is determined in step S110 that the PM accumulation amount Qpm is equal to or greater than the threshold value Qpmref, it is determined that there is a sufficiently low possibility that the PM accumulation amount Qpm will become too small even if fuel is cut off to the engine 22 and particulate matter is burned, and fuel cut to the engine 22 is permitted (step S150), after which the routine ends.

If it is determined in step S120 that the filter temperature Tf is less than the threshold value Tfref, it is determined that even if fuel is cut to the engine 22, the possibility that the PM accumulation amount Qpm will become too small because particulate matter is difficult to burn is sufficiently low, and fuel cut to the engine 22 is permitted (step S150), and this routine is terminated.

If step S110 determines that the PM accumulation amount Qpm is less than the threshold Qpmref, and step S120 determines that the filter temperature Tf is equal to or greater than the threshold Tfref, it is determined that cutting fuel to the engine 22 may result in the combustion of particulate matter, causing the PM accumulation amount Qpm to become too low, and it is then determined whether it is time to change the gear position of the manual transmission 30 (step S130). In a manual transmission vehicle, when changing the gear position of the manual transmission 30, basically, the clutch 40 is released by depressing the clutch pedal 42, the gear position of the manual transmission 30 is changed in response to operation of the shift lever 32, and the clutch 40 returns to the engaged state via the slip engagement state as the clutch pedal 42 is gradually released. Based on this, the time when the gear position of the manual transmission 30 is changed may be the period from when depression of the clutch pedal 42 begins to end (from when the clutch 40 is disengaged to when it returns to an engaged state), or it may be the period from when the gear position of the manual transmission 30 begins to change to when the change is completed.

If it is determined in step S130 that the manual transmission 30 is not currently being changed to a different gear position, fuel cutoff to the engine 22 is prohibited (step S140), and the routine ends. This prevents the PM accumulation amount Qpm from becoming too small due to fuel cutoff to the engine 22.

If step S130 determines that it is time to change the gear position of the manual transmission 30, fuel cut-off of the engine 22 is permitted (step S150), and the routine ends. Prohibiting fuel cut-off of the engine 22 when changing the gear position of the manual transmission 30 raises concerns that the engine 22 may rev up and deteriorate drivability. In contrast, in this embodiment, permitting fuel cut-off of the engine 22 when changing the gear position of the manual transmission 30 suppresses engine 22 rev-up and reduces deterioration of drivability. The inventors have confirmed through experiments and analysis that the time required to change the gear position of the manual transmission 30 is generally on the order of several tens to several hundred milliseconds, and that the reduction in the PM accumulation amount Qpm due to fuel cut-off of the engine 22 is relatively small, and that the reduction in the particulate matter capture rate of the PM filter 136 is also relatively small (within an acceptable range). Furthermore, in order to more fully suppress revving of the engine 22, it is preferable to change the gear position of the manual transmission 30 during the period from when depression of the clutch pedal 42 begins to end (from when the clutch 40 is disengaged to when it returns to an engaged state), rather than during the period from when the gear position of the manual transmission 30 begins to change to when the gear position change is completed.

If the filter temperature Tf is equal to or higher than the overheat temperature Tfot in step S100, it is determined that there is a possibility that the PM filter 136 will overheat due to the execution of a fuel cut to the engine 22, and the fuel cut to the engine 22 is prohibited (step S140), and the routine ends. This makes it possible to prevent the PM filter 136 from overheating due to the execution of a fuel cut to the engine 22.

In the vehicle 20 of this embodiment described above, when the PM accumulation amount Qpm is less than the threshold value Qpmref and the filter temperature Tf is equal to or greater than the threshold value Tfref, fuel cut-off to the engine 22 is generally prohibited. However, even when the PM accumulation amount Qpm is equal to or less than the threshold value Qpmref and the filter temperature Tf is equal to or greater than the threshold value Tfref, fuel cut-off to the engine 22 is permitted when the gear position of the manual transmission 30 is changed. This makes it possible to suppress revving of the engine 22 when the gear position of the manual transmission 30 is changed, and to suppress deterioration of drivability.

Furthermore, in the vehicle 20 of this embodiment, when the filter temperature Tf is equal to or higher than the overheat temperature Tfot, which is higher than the threshold value Tfref, fuel cut-off of the engine 22 is prohibited regardless of whether or not the manual transmission 30 is changing gear positions. This makes it possible to prevent the PM filter 136 from overheating due to fuel cut-off of the engine 22.

In the above-described embodiment, the engine 22 has a port injection valve 126 and an in-cylinder injection valve 127. However, the engine 22 may have only one of the port injection valve 126 and the in-cylinder injection valve 127.

In the above-described embodiment, the manual transmission 30 is configured as a six-speed transmission. However, the manual transmission 30 may also be configured as a four-speed transmission, a five-speed transmission, an eight-speed transmission, etc.

The following explains the correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section. In the embodiment, the engine 22 corresponds to the "engine," the manual transmission 30 corresponds to the "manual transmission," and the electronic control unit 50 corresponds to the "control device."

The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, as the embodiments are examples used to specifically explain the form for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

The above describes embodiments for implementing the present disclosure, but the present disclosure is in no way limited to these embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the spirit of the present disclosure.

This disclosure can be used in the vehicle manufacturing industry, etc.

20 vehicle, 22 engine, 23 crankshaft, 24 engine ECU, 30 manual transmission, 32 shift lever, 40 clutch, 42 clutch pedal, 50 electronic control unit, 51 ignition switch, 53 accelerator pedal, 54 accelerator pedal position sensor, 55 brake pedal, 56 brake pedal position sensor, 58 vehicle speed sensor, 122 air cleaner, 123 intake pipe, 123a air flow meter, 123t temperature sensor, 124 throttle valve, 124a throttle valve position sensor, 125 surge tank, 125a pressure sensor, 126 port injection valve, 127 in-cylinder injection valve, 128 intake valve, 129 combustion chamber, 130 spark plug, 132 piston, 133 exhaust valve, 134 exhaust pipe, 135 purification device, 136 PM filter, 136a differential pressure sensor, 137 front air-fuel ratio sensor, 138 rear air-fuel ratio sensor, 140 crank position sensor, 142 water temperature sensor, 144 cam position sensor.

Claims (2)

A vehicle comprising: an engine having an exhaust system equipped with a filter that captures particulate matter; a manual transmission that transmits power from the engine to drive wheels while changing gears in response to a driver's shift operation; a clutch that can disconnect the engine from the manual transmission in response to a driver's operation of a clutch pedal; and a control device that prohibits fuel cut-off of the engine when an amount of accumulated particulate matter is less than a predetermined amount and the temperature of the filter is equal to or higher than a first predetermined temperature,
the control device permits the fuel cut when the gear position is changed even when the amount of accumulated particulate matter is less than the predetermined amount and the temperature of the filter is equal to or higher than the first predetermined temperature.
vehicle. 2. The vehicle according to claim 1,
the control device prohibits the fuel cut when the temperature of the filter is equal to or higher than a second predetermined temperature that is higher than the first predetermined temperature, regardless of whether the gear position is being changed or not.
vehicle.