JP7506484B2 - Vehicle Powertrain - Google Patents

Description

The present invention relates to a vehicle powertrain having an engine and a transmission that changes the rotation speed of the output shaft.

For example, in a turbocharged engine for an automobile, it is known to provide an air bypass flow path that connects the inlet side and the outlet side of a compressor, and an air bypass valve that opens and closes the air bypass flow path.
For example, Patent Document 1 describes that an air bypass valve is opened in order to suppress the generation of surge pressure, which is a sudden increase in intake pressure between the compressor and the throttle valve, when the throttle valve is suddenly closed from a supercharging state. It also describes that the air bypass valve is opened in response to the sudden closure of the throttle valve in torque reduction control for protecting the drive system.
Patent Document 2 describes a system in which a diaphragm-type actuator is used to open and close an air bypass valve, in which the positive pressure in the diaphragm valve is released during sudden deceleration to quickly open the air bypass valve and prevent the occurrence of a surge.
Patent Document 3 describes a method in which an air bypass valve is opened and closed by an electric actuator and is controlled in accordance with the amount of intake air of the engine immediately before the throttle valve is closed, in order to prevent a surge while suppressing deterioration of drivability.

JP 2016-20691 A Japanese Patent Application Laid-Open No. 5-195798 JP 2018-17179 A

In vehicles equipped with a manual transmission in which the driver manually changes gears, there are those that perform rotation speed synchronization control (blipping control) to make the engine speed (output shaft rotation speed) follow the input shaft rotation speed (target rotation speed) after the transmission shifts gears when changing gears, thereby suppressing any discomfort or vehicle shock felt by the driver when the clutch is engaged.
During blipping control, when shifting gears in the direction of increasing the reduction ratio (shifting down), the throttle valve is opened to increase the amount of intake air, thereby increasing the engine output torque and bringing the engine speed closer to the target speed.
On the other hand, when shifting gears in the direction of decreasing the reduction ratio (shifting up), after the driver takes his/her foot off the accelerator, fuel injection is stopped (fuel cut), the engine output torque is reduced, and the engine speed is brought closer to the target speed.

However, when engine speed is reduced by fuel cut, a certain amount of time is required from when the driver takes his/her foot off the accelerator at the start of a gear change until fuel cut is actually performed, so the reduction in engine speed is slow and responsiveness is low.
As a result, when the gear is changed quickly, the clutch is engaged before the engine speed can adjust accordingly, which can give the driver a strange feeling or cause shocks in the vehicle body.
On the other hand, if the clutch is engaged after the engine speed coincides with the target speed, a quick gear change cannot be performed, and the idle time with the driving force cut off becomes long.
In view of the above problems, an object of the present invention is to provide a vehicle powertrain that improves the responsiveness of the engine output shaft rotation speed during an upshift.

The present invention solves the above-mentioned problems by the following solving means.
The invention according to claim 1 includes an engine having an air bypass valve that opens and closes an air bypass flow passage that connects the upstream side and downstream side of a compressor of a turbocharger, a transmission that changes the rotation output of the engine and performs a gear change operation to switch between a plurality of discretely set gear ratios, a clutch provided between the engine and the transmission, a gear change operation detection unit that detects the start of a gear change operation that changes the gear ratio in the transmission so as to reduce the reduction ratio, a target speed calculation unit that calculates a target value of the output shaft rotation speed of the engine after the gear change in response to the start of the gear change operation, and a target speed calculation unit that reduces the output shaft rotation speed of the engine to the target value in response to the start of the gear change operation. and an engine control unit which controls the engine to open the air bypass valve, the transmission having a gear shift operation unit to which a driver's gear shift operation is input, the engine control unit opening the air bypass valve when the gear shift operation is detected after the clutch is disengaged while the output shaft rotation speed of the engine is decreasing , stopping fuel injection into the engine while the air bypass valve is open, and restarting fuel injection into the engine and closing the air bypass valve after the output shaft rotation speed reaches the target value and before the gear shift operation is completed , thereby maintaining the target value until the clutch is engaged .
According to this, when changing gears in the direction of decreasing the reduction ratio (shifting up), the air bypass valve is kept open until the output shaft rotation speed of the engine reaches a target value, thereby reducing the boost pressure of the turbocharger and the amount of intake air into the engine, thereby making it possible to speed up the drop in the output shaft rotation speed and shorten the time it takes to reach the target rotation speed.
This makes it possible to reduce the discomfort and shock that occurs when the clutch is engaged, even when a quick gear change operation is performed.

The invention of claim 2 is the powertrain for a vehicle described in claim 1, characterized in that the transmission has an operating force sensor that detects the operating force applied to the gear shift operating unit by the driver and the direction in which the operating force is applied, and the target speed calculation unit calculates the target value based on the post-gear ratio estimated based on the output of the operating force sensor.
According to this, based on the output of the operating force sensor, it is determined whether the started gear change operation is a gear change (upshift) that reduces the reduction ratio, and the output shaft rotation speed can begin to decrease before the gear selection operation is completed, so that the target rotation speed can be reached more quickly.

As described above, the present invention provides a vehicle powertrain that improves the responsiveness of the engine output shaft rotation speed during upshifting.

1 is a diagram showing a schematic configuration of an engine used in an embodiment of a vehicle powertrain to which the present invention is applied; 1 is a block diagram illustrating a system configuration related to blipping control in a vehicle powertrain according to an embodiment of the present invention; 3 is a diagram showing a shift pattern in a gear shift operation unit of a manual transmission provided in the power train of the embodiment. FIG. 4 is a flowchart showing blipping control during gear shifting in the powertrain of the embodiment. 5 is a timing chart showing the state of the engine during upshifting in a powertrain that is a comparative example of the present invention. 4 is a timing chart showing the state of the engine during upshifting in the powertrain of the embodiment.

Hereinafter, an embodiment of a vehicle powertrain to which the present invention is applied will be described.
The vehicle power train according to the embodiment is installed in an automobile such as a passenger car, and has an engine and a manual transmission that changes the speed of the engine's output.
The engine is, for example, a direct injection turbocharged gasoline engine.

FIG. 1 is a diagram showing a schematic configuration of an engine used in a powertrain according to an embodiment.
As shown in FIG. 1, the engine 1 is configured to include a main body 10, an intake device 20, an exhaust device 30, a turbocharger 40, a fuel supply device 50, an evaporated fuel treatment device 60, an EGR device 70, an engine control unit (ECU) 100 (see FIG. 2), and the like.

The main body 10 is a main engine portion of the engine 1, and is, for example, a horizontally opposed four-cylinder, four-stroke DOHC gasoline direct injection engine.
The main body 10 includes a crankshaft 11, a cylinder block 12, a cylinder head 13, an intake valve drive system 14, an exhaust valve drive system 15, a spark plug 16, etc.

The crankshaft 11 is an output shaft of the engine 1, and pistons of each cylinder (not shown) are connected to the crankshaft 11 via connecting rods.
The cylinder block 12 is a block-shaped member having cylinders for each cylinder, and is divided into two parts, left and right, with the crankshaft 11 in between.
The right half of the cylinder block 12 (left and right here refer to the left and right sides of the vehicle body when mounted vertically in the vehicle) is provided with the first and third cylinders, located in that order from the front side of the vehicle, and the left half is provided with the second and fourth cylinders.

A crankcase portion in which the crankshaft 11 is housed is provided at the joint between the left and right halves of the cylinder block 12 .
The crankshaft 11 is rotatably supported by main bearings provided in the cylinder block 12 .
The cylinder block 12 is provided with a crank angle sensor (not shown) that detects the angular position of the crankshaft 11 .

The cylinder heads 13 are provided on both left and right ends of the cylinder block 12 .
The cylinder head 13 is configured to include a combustion chamber, an intake port, an exhaust port, an intake valve, an exhaust valve, etc.
The combustion chamber is a recess provided opposite to the crown surface of a piston (not shown), and constitutes a part of a space in which the air-fuel mixture compressed by the piston is burned.
The intake port is a flow passage that introduces combustion air (fresh air) into the combustion chamber.
The exhaust port is a passage through which burnt gas (exhaust gas) is discharged from the combustion chamber.
The intake valve and the exhaust valve open and close the intake port and the exhaust port, respectively, at predetermined valve timing.

The intake valve drive system 14 and the exhaust valve drive system 15 are each configured to include, for example, a cam sprocket driven via a timing chain (not shown) from a crank sprocket provided at the end of the crankshaft 11, and a camshaft driven by the cam sprocket.
Furthermore, the intake valve drive system 14 and the exhaust valve drive system 15 each include a variable valve timing mechanism that rotates the cam sprocket and the camshaft relatively around the central axis of rotation using a hydraulic actuator in response to a command from the engine control unit 100 .

The spark plug 16 generates an electrical spark in the combustion chamber at a predetermined ignition timing in response to an ignition signal sent by the engine control unit 100, thereby igniting the air-fuel mixture.

The intake system 20 takes in outside air and introduces it into the intake port of the cylinder head 13 as combustion air.
The intake system 20 includes an intake duct 21, an air cleaner 22, an air flow meter 23, an air bypass valve 24, an intercooler 25, a throttle 26, an intake manifold 27, a tumble generator valve 28, and the like.

The intake duct 21 is a pipe through which combustion air drawn in from the outside is transported.
A compressor 41 of a turbocharger 40 is provided in the middle of the intake duct 21, as described below.

The air cleaner 22 is provided near the entrance of the intake duct 21 and includes an air cleaner element that filters out foreign matter such as dust, and an air cleaner case that houses the air cleaner element.
The air flow meter 23 is a sensor that is provided at the outlet of the air cleaner 22 and measures the flow rate of air passing through.
The output of the air flow meter 23 is transmitted to the engine control unit 100 and is used for controlling the fuel injection amount and estimating the load state.

The air bypass valve 24 opens and closes a bypass flow passage that allows a portion of the air flowing inside the intake duct 21 to bypass between the upstream side and downstream side of the compressor 41.
The opening degree of the air bypass valve 24 (the amount of air bypassed) can be changed in response to a command from the engine control unit 100. The air bypass valve 24 may be, for example, a valve whose opening degree can be switched between fully closed and fully open, or a valve whose opening degree can be controlled to any degree between fully closed and fully open.
During supercharging, a portion of the supercharged fresh air in the intake duct 21 downstream of the compressor 41 is returned to the upstream side of the compressor 41 by opening the air bypass valve 24 .
This makes it possible to reduce the pressure difference between the upstream side and the downstream side of the compressor 41 .
The air bypass valve 24 is opened, for example, to protect the blades of the turbine 42 during deceleration or to suppress the flow rate of purge gas when the purge valve 66 has a stuck open fault, but is normally closed.

The intercooler 25 cools the air compressed in the compressor 41 by exchanging heat with, for example, running wind (airflow generated around the vehicle body as the vehicle moves).
The throttle 26 is equipped with a throttle valve that adjusts the amount of intake air in order to adjust the output of the engine 1.
The throttle valve is an electric butterfly valve that is driven to open and close by an electric actuator in response to a command from the engine control unit 100 to a predetermined opening degree.
The throttle 26 is disposed adjacent to the outlet of the intercooler 25 .
A pressure sensor 26a for detecting the intake pipe pressure is provided on the inlet side (upstream side) of the throttle 26.
The output of the pressure sensor 26 a is transmitted to the engine control unit 100 .

The intake manifold 27 is a branch pipe that distributes the air coming out of the throttle 26 to the intake ports of each cylinder.
The intake manifold 27 is provided with a pressure sensor 27 a that detects the intake pipe pressure downstream of the throttle 26 .
The output of the pressure sensor 27 a is transmitted to the engine control unit 100 .

The tumble generator valve (TGV) 28 is a gas flow control valve that is provided in the flow path of the intake manifold 27 and controls the state of the tumble flow formed in the cylinder by switching the state of the air flow path from the intake manifold 27 to the intake port.

The flow passage in the intake manifold 27 has a cross section divided into two by a partition wall (not shown) in a partial region on the downstream side (the intake port side).
The TGV 28 transitions between a closed state in which it substantially blocks the flow path on one side of the bulkhead, and an open state in which it opens it.
The TGV 28 has a function of promoting tumble flow in the cylinder when in a closed state relative to an open state.
The TGV 28 is closed, for example, when the engine 1 is in a region of relatively low speed and low load, thereby strengthening the tumble flow in the cylinder, increasing the combustion speed, improving the degree of constant volume, and improving thermal efficiency and torque.
On the other hand, when the engine 1 is in a range of relatively high revolution speed and high load, the gas flow within the cylinder is inherently vigorous, and the TGV 28 is opened to give priority to the charging efficiency.
The TGV 28 is switched in response to a command from the engine control unit 100 .

The exhaust device 30 discharges burnt gas (exhaust gas) from an exhaust port of the cylinder head 13 .
The exhaust system 30 includes an exhaust manifold 31, an exhaust pipe 32, a front catalyst 33, a rear catalyst 34, a silencer 35, and the like.

The exhaust manifold 31 is an exhaust gas flow path (pipe) that collects the exhaust gas from the exhaust ports of each cylinder and introduces it into the turbine 42 of the turbocharger 40.

The exhaust pipe 32 is an exhaust gas flow path (pipe) that discharges exhaust gas from a turbine 42 of the turbocharger 40 to the outside.
A front catalyst 33 and a rear catalyst 34 are provided in this order in the middle of the exhaust manifold 31 from the turbine 42 side.

The front catalyst 33 and the rear catalyst 34 are three-way catalysts that carry a precious metal such as platinum, rhodium, or palladium on a carrier such as alumina, and reduce HC, CO, and NOx.
A front A/F sensor 33a and a rear A/F sensor 33b are provided at the inlet and outlet of the front catalyst 33, respectively, for detecting the air-fuel ratio (A/F) based on the properties of exhaust gas.
The outputs of the front A/F sensor 33a and the rear A/F sensor 33b are transmitted to the engine control unit 100 and are used for air-fuel ratio feedback control of the fuel injection amount, deterioration diagnosis of the front catalyst 33, and the like.

The silencer 35 is disposed adjacent to the outlet of the exhaust pipe 32 and serves to reduce the acoustic energy of the exhaust gases to suppress exhaust noise.
The exhaust pipe 32 branches into, for example, two pipes near the outlet, and a silencer 35 is provided on each of the pipes downstream of the branching point.

The turbocharger 40 is an exhaust turbine supercharger that compresses fresh air by utilizing the energy of exhaust gas.
The turbocharger 40 includes a compressor 41, a turbine 42, a bearing housing 43, a wastegate valve 44, and the like.

The compressor 41 is a centrifugal compressor that compresses the combustion air.
The turbine 42 drives the compressor 41 by utilizing the energy of the exhaust gas.
The bearing housing 43 is provided between the compressor 41 and the turbine 42 .
The bearing housing 43 connects the housings of the compressor 41 and the turbine 42, and has a bearing that rotatably supports a shaft that connects the compressor wheel and the turbine wheel, a lubrication device, and the like.

The wastegate valve 44 opens and closes a wastegate flow passage that allows a portion of the exhaust gas to bypass from the inlet side to the outlet side of the turbine 42 .
The wastegate valve 44 has an electric actuator for opening and closing, and an opening sensor (not shown) for detecting the opening position, and its opening is controlled by the engine control unit 100.

The fuel supply device 50 supplies fuel to each cylinder of the engine 1 .
The fuel supply device 50 includes a fuel tank 51, a feed pump 52, a feed line 53, a high-pressure pump 54, a high-pressure fuel line 55, an injector 56, and the like.

The fuel tank 51 is a container in which gasoline, which is a fuel, is stored.
The feed pump 52 discharges the fuel in the fuel tank 51 and transports it to the high-pressure pump 54 .
The feed line 53 is a fuel flow passage that transports the fuel discharged from the feed pump 52 to the high-pressure pump 54 .

The high-pressure pump 54 is attached to the cylinder head 13 and is driven via a camshaft to increase the fuel pressure.
The high-pressure pump 54 is equipped with a plunger that reciprocates inside the cylinder in conjunction with the rotation of the camshaft to pressurize the fuel, and an electromagnetic metering valve. The fuel pressure in the high-pressure fuel line 55 can be adjusted by controlling the duty ratio of the electromagnetic metering valve using the engine control unit 100.
The high-pressure fuel line 55 is a fuel passage that transports the fuel pressurized by the high-pressure pump 54 to an injector 56 provided in each cylinder.
The injector 56 is an injection valve that injects fuel supplied from the high-pressure fuel line 55 into the combustion chamber of each cylinder in response to an injection signal from the engine control unit 100 .

The evaporative fuel treatment device 60 temporarily stores the fuel evaporative gas (evaporation) generated when the fuel (gasoline) evaporates in the fuel tank 51 in a canister 61, and when the engine 1 is operating, introduces the gas into the intake duct 21 as purge gas (canister purging) and combusts it in the combustion chamber.
The evaporated fuel processing device 60 includes a canister 61, an evaporative leak check module 62, purge lines 63, 64, and 65, a purge valve 66, a pressure sensor 67, an ejector 68, and the like.

The canister 61 is a charcoal canister configured by accommodating activated charcoal capable of absorbing fuel evaporative gas in a case.
The canister 61 receives fuel evaporative gas from the fuel tank 51 via a pipe 61a.
A fuel cut valve 61b for preventing the inflow of liquid phase fuel is provided at the end of the pipe 61a on the fuel tank 51 side.

The evaporative leak check module (ELCM) 62 is located adjacent to the canister 61 and automatically detects any fuel evaporative gas leaks from the evaporative fuel treatment device 60.

The purge lines 63, 64, and 65 are pipes that introduce the fuel evaporative gas stored in the canister 61 into the intake duct 21 of the intake device 20 as purge gas when the engine 1 is operating.
The upstream end of the purge line 63 is connected to the canister 61 , and the downstream end is connected to the inlet side of a purge valve 66 .
The upstream end of the purge line 64 is connected to the outlet side of a purge valve 66 , and the downstream end is connected to the intake manifold 27 .
A check valve 64 a is provided in the middle of the purge line 64 .
The check valve 64 a is a check valve that prevents the backflow of purge gas from the intake manifold 27 side to the purge valve 66 side.

The purge line 65 introduces a portion of the purge gas that flows out from the purge valve 66 to the purge line 64 into the ejector 68 .
The purge line 65 branches off from a region between the purge valve 66 and the check valve 64 a in the purge line 64 , and its downstream end is connected to a region downstream of the nozzle 68 b in the ejector 68 .
A check valve 65 a is provided in the middle of the purge line 65 .
The check valve 65 a is a check valve that prevents the backflow of purge gas from the ejector 68 side to the purge valve 66 side.

The purge valve 66 is an electromagnetic valve that can be switched between an open state in which the purge gas can pass from the purge line 63 to the purge lines 64 and 65, and a closed state in which the purge lines 63 and 64 are blocked from each other.
The purge valve 66 is opened and closed in response to an open command and a close command from the engine control unit 100 .

The pressure sensor 67 is provided in the middle of the purge line 63 and detects the pressure of the purge gas in the purge line 63 .
The output of the pressure sensor 67 is transmitted to the engine control unit 100 .

The ejector 68 is a negative pressure generating device that utilizes the pressure difference between the upstream and downstream sides of the compressor 41 of the turbocharger 40 to suck in purge gas and introduce it into the intake duct 21 .
The ejector 68 is formed in a cylindrical container shape and includes an introduction pipe 68a, a nozzle 68b, a discharge port 68c, and the like.
The intake pipe 68 a is a pipe that introduces air extracted from a region of the intake duct 21 downstream of the compressor 41 to the upstream end of the ejector 68 .
The nozzle 68b throttles the air flow introduced from the introduction pipe 68a and flowing inside the ejector 68 to increase the flow speed, thereby generating negative pressure by the Venturi effect.

The downstream end of the purge line 65 is connected to a region downstream of the nozzle 68b of the ejector 68, and the purge gas is sucked into the ejector 68 by the negative pressure generated by the nozzle 68b and merges with the air flow.
The discharge port 68 c is provided at the downstream end of the ejector 68 , and is a communication point through which the joined air and purge gas are introduced from inside the ejector 68 to a region in the intake duct 21 upstream of the compressor 41 .

The EGR device 70 performs exhaust gas recirculation (EGR) by extracting a portion of the exhaust gas from the exhaust manifold 31 as EGR gas and introducing it into the intake manifold 27 .
The EGR device 70 includes an EGR passage 71, an EGR cooler 72, an EGR valve 73, and the like.

The EGR passage 71 is a pipe that introduces exhaust gas (EGR gas) from the exhaust manifold 31 to the intake manifold 27 .
The EGR cooler 72 is provided midway through the EGR passage 71 and cools the EGR gas flowing through the EGR passage 71 by heat exchange with the cooling water of the engine 1, thereby enabling cooled EGR.

The EGR valve 73 is provided downstream of the EGR cooler 72 in the EGR passage 71 , and is a flow rate adjusting valve that adjusts the flow rate of EGR gas passing through the EGR passage 71 .
The EGR valve 73 has a valve body that is driven by an electric actuator such as a solenoid.
During steady operation, the opening of the EGR valve 73 is controlled by the engine control unit 100 using an opening map that is set based on a predetermined target EGR rate (EGR gas flow rate/intake air flow rate).
The opening map is configured so that a target opening of the EGR valve 73 is read out from the rotation speed of the crankshaft 11 of the engine 1 and the load rate relative to the total load.
The opening map is set so that the combustion speed (or the mean effective pressure in the cylinder) and anti-knocking performance are appropriate in each operating range of the engine 1 .
During steady operation, the EGR valve 73 is controlled in opening/closing and in opening rate in response to an opening degree command value given by the engine control unit 100 .

FIG. 2 is a block diagram showing a schematic system configuration related to blipping control in a vehicle powertrain according to the embodiment.
The system includes an engine control unit 100 .
The engine control unit (ECU) 100 is an engine control device that comprehensively controls the engine 1 and its auxiliaries.
The engine control unit 100 is communicatively connected to each of the sensors and devices provided in the engine 1 directly or via an in-vehicle LAN or the like.
The engine control unit 100 is configured to include, for example, an information processing means such as a CPU, storage means such as a RAM and a ROM, an input/output interface, and a bus connecting these.
The output of each sensor provided in the engine 1 is transmitted to the engine control unit 100, and the engine control unit 100 is also capable of outputting control signals to controlled objects such as actuators, valves, spark plugs, injectors, etc. provided in the engine 1.

An accelerator pedal sensor 101 is connected to the engine control unit 100 .
The accelerator pedal sensor 101 detects the amount of operation (depression amount) of an accelerator pedal, which is an operation unit through which a driver inputs an acceleration request.
Under normal circumstances (when blipping control is not being executed), the engine control unit 100 calculates a driver requested torque based on the output of the accelerator pedal sensor 101, etc., and adjusts the output (torque) of the engine 1 by controlling the opening of the throttle 26, the opening and closing of the air bypass valve 24, the opening of the wastegate valve 44, the valve timing, the ignition timing, the fuel injection amount and injection timing, etc., so that the torque actually generated by the engine 1 (actual torque) approaches the driver requested torque.

The engine control unit 100 is connected to a shift lever sensor 102, a clutch switch 103, a brake switch 104, and the like.
The shift lever sensor 102 is an operating force sensor that detects the operating force and operating direction of the driver on a shift lever (typically a shift knob provided at the upper end) which is a gear shift operating part of a manual transmission.

FIG. 3 is a diagram showing a shift pattern in a gear shift operation unit of a manual transmission provided in the power train of the embodiment.
In the embodiment, the manual transmission has, as an example, a shift pattern consisting of six speeds (1 to 6) and a reverse (R) using a so-called vertical H pattern.
The shift pattern is as follows, with respect to the neutral position of the shift lever (the position where the return spring returns to in neutral), the front left is 1st gear, the rear left is 2nd gear, the front center is 3rd gear, the rear center is 4th gear, the front right is 5th gear, and the rear right is 6th gear.
When shifting to reverse, the reverse lock release knob provided on the shift lever is pulled and displaced to the right rear (further to the right of sixth gear) to a position.
Therefore, when changing gears other than between 1st and 2nd gear, 3rd and 4th gear, and 5th and 6th gear, a lateral input is applied to the shift lever.
Therefore, it is possible to determine (predict) whether a shift is being upshifted or downshifted depending on the presence or absence of a lateral force at the start of a gear shift operation and its direction.

The shift lever sensor 102 detects the operating forces in the front-rear and left-right directions applied to a shift knob provided at the upper end of the shift lever, and provides the detected forces to the engine control unit 100 .
The clutch switch 103 is provided between the engine 1 and the manual transmission, and is turned on when the clutch is disengaged.
The brake switch 104 is a switch that is turned on when the vehicle's brake device is activated.
The accelerator pedal sensor 101, the shift lever sensor 102, the clutch switch 103, and the brake switch 104 cooperate to function as a gear shifting operation detection unit of the present invention.

In the powertrain of the embodiment, while the clutch is disengaged during a gear shift operation by the driver, blipping control is performed to control the output shaft rotation speed (engine speed) of the engine 1 to a target speed corresponding to the reduction ratio of the gear stage after the gear shift.
FIG. 4 is a flowchart showing blipping control during gear shifting in the powertrain of the embodiment.
Each step will be explained in order below.

<Step S01: Gear shift operation start detection determination>
The engine control unit 100 determines whether or not a gear shift operation has been started by the driver.
For example, when the accelerator pedal sensor 101 detects that the accelerator is off, the clutch switch 103 detects that the clutch is disengaged, and the shift lever sensor 102 detects an operating force on the shift knob, it can be determined that a gear shift operation has begun.
If the start of a gear shift operation is detected, the process proceeds to step S02, otherwise the series of processes ends (returns).

<Step S02: Shift-up determination>
The engine control unit 100 determines whether the gear change operation that has started is an upshift, which is a gear change in which the reduction ratio becomes smaller.
For example, as shown in FIG. 3, when a gear change operation is started while the vehicle is traveling in third gear, there is generally a possibility that the vehicle will be upshifted to fourth gear or downshifted to second gear.
When shifting down to second gear, an input is given to the shift knob in the vehicle width direction (to the left in this case).
The engine control unit 100 can determine (predict) whether the gear shift operation is an upshift or a downshift, which is a gear shift with a larger reduction ratio, based on the operating force and its direction detected by the shift lever sensor 102.
Also, when the brake switch 104 detects the operation of the brake device, it may be determined that a downshift has occurred.
If it is determined that the current gear shift operation is an upshift, the process proceeds to step S03, and otherwise (if it is determined that the current gear shift operation is a downshift), the process proceeds to step S06.

<Step S03: Calculate target rotation speed>
The engine control unit 100 calculates a target rotation speed of the engine 1 after the upshift.
The target rotation speed is set so as to match the input shaft rotation speed of the transmission after the gear shift.
The target rotation speed can be calculated, for example, from the reduction ratio after gear shift in the transmission, the reduction ratio in the final reduction gear unit, the outer diameter of the wheels, and the current traveling speed (vehicle speed) of the vehicle.
At this time, the engine control unit 100 functions as a target speed calculation section of the present invention.
Then, proceed to step S04.

<Step S04: Engine Speed Reduction Control>
The engine control unit 100 performs engine speed reduction control by fully closing the throttle 26, stopping fuel injection from the injector 56 (fuel cut), and opening the air bypass valve 24 to quickly reduce the engine speed.
Then, proceed to step S05.

<Step S05: Determining engine speed>
The engine control unit 100 compares the current engine speed, which is calculated based on the output of the crank angle sensor, with the target engine speed determined in step S03.
If the current engine speed is equal to or lower than the target speed, the process proceeds to step S09; otherwise, the process returns to step S04 to repeat the subsequent processes.

<Step S06: Calculate target rotation speed>
The engine control unit 100 calculates a target rotation speed of the engine 1 after the downshift.
The target rotation speed can be calculated, for example, from the reduction ratio after gear shift in the transmission, the reduction ratio in the final reduction gear unit, the outer diameter of the wheels, and the current traveling speed (vehicle speed) of the vehicle.
Then, proceed to step S07.

<Step S07: Engine Speed Increase Control>
The engine control unit 100 performs engine speed increase control by increasing the opening of the throttle 26 to increase the engine speed.
Then, proceed to step S08.

<Step S08: Determining engine speed>
The engine control unit 100 compares the current engine speed, which is calculated based on the output of the crank angle sensor, with the target engine speed determined in step S06.
If the current engine speed is equal to or higher than the target speed, the process proceeds to step S09; otherwise, the process returns to step S06 to repeat the subsequent processes.

<Step S09: Engine Speed Maintenance Control>
The engine control unit 100 controls the opening of the throttle 26 so that the engine speed is maintained at a target speed while fuel is being injected from the injector 56 and the air bypass valve 24 is closed.
Then, proceed to step S10.

<Step S10: Clutch engagement detection>
The engine control unit 100 detects, based on the output of the clutch switch 103, whether or not the clutch has returned to the engaged state.
If the fastened state is detected, the process proceeds to step S11, otherwise the process returns to step S09 and the subsequent processes are repeated.

<Step S11: Return to normal control>
The engine control unit 100 ends the blipping control and returns to normal driving control in which the opening of the throttle 26, the opening and closing of the air bypass valve 24, etc. are controlled based on the required torque that is set according to the output of the accelerator pedal sensor 101, etc.
Then, the series of processes ends.

The effects of this embodiment will be described in comparison with a comparative example of the present invention which will be described below.
In the power train of the comparative example, in the blipping control at the time of upshifting, the air bypass valve is not opened, and the engine speed is reduced by closing the throttle and cutting the fuel.

FIG. 5 is a timing chart showing the state of the engine during upshifting in a power train that is a comparative example of the present invention.
In FIG. 5, from the top, the chart shows engine speed, shift position, brake operation, clutch operation, accelerator operation, fuel cut state (fuel cut at the top), required torque due to accelerator operation, required torque based on blipping control, and output torque of engine 1.
In this comparative example, when the clutch is disengaged due to upshifting, the engine speed is reduced to the target speed by cutting fuel, but the engine speed decreases slowly and it takes a long time to reach the target speed.
For this reason, for example, if the driver quickly shifts up and re-engages the clutch early, the engine speed will be higher than the target speed, and the vehicle will jump out (temporarily accelerate with a shock) when the clutch is engaged, causing a sense of discomfort for the driver and shock to the vehicle body.

FIG. 6 is a timing chart showing the state of the engine during an upshift in the powertrain of the embodiment.
In addition to the parameters shown in FIG. 5, FIG. 6 also shows the open/close state of the air bypass valve (the upper side of the diagram is open, and the lower side is closed).
In the embodiment, by opening the air bypass valve 24 when the engine speed is reduced in the blipping control, the engine speed can be reduced more quickly than in the comparative example.
This shortens the time it takes for the engine speed to reach the target speed, and prevents the occupants from feeling uncomfortable or the vehicle body from experiencing shocks due to a discrepancy between the rotational speed of the drive system and the engine speed, even when the clutch is engaged early due to a quick gear change operation.

As described above, according to this embodiment, the following effects can be obtained.
(1) When changing gears in the direction of decreasing the reduction ratio (shifting up), the air bypass valve 24 is kept open until the rotational speed of the engine 1 reaches the target rotational speed. This reduces the boost pressure of the turbocharger 40 and reduces the amount of intake air of the engine 1, thereby making it possible to quickly reduce the engine rotational speed and shorten the time it takes to reach the target rotational speed.
This makes it possible to reduce the discomfort and shock that occurs when the clutch is engaged, even when a quick gear change operation is performed.
(2) By stopping fuel injection (fuel cut) when the engine speed drops during blipping control, the engine speed can be reduced more quickly, enhancing the above-mentioned effects.
(3) Based on the operating force applied to the shift lever detected by the shift lever sensor 102, it is determined whether the started gear change operation is a gear change (upshift) that reduces the reduction ratio, and the engine speed can begin to decrease before the gear selection operation (engagement of the gear after the gear change) is completed, so that the target rotation speed can be reached more quickly.

(Modification)
The present invention is not limited to the above-described embodiment, and various modifications and variations are possible, which are also within the technical scope of the present invention.
(1) The configuration of the vehicle powertrain is not limited to the above-described embodiment and may be modified as appropriate.
For example, the engine in the embodiment is, as an example, a horizontally opposed four-cylinder gasoline direct injection engine, but the number of cylinders, cylinder layout, fuel injection method, etc. can be changed as appropriate, and the engine can also use a fuel other than gasoline or an engine that operates based on a theoretical cycle other than the Otto cycle, such as a diesel engine.
(2) In the embodiment, a manual transmission is used as an example of the transmission. However, the present invention can be applied to other types of transmissions as long as the transmission is capable of shifting between a plurality of discretely set gear ratios.
For example, the transmission may be an AMT in which a speed change mechanism similar to that of a manual transmission is operated by an actuator, a DCT, or a stepped AT using a planetary gear set.

REFERENCE SIGNS LIST 1 engine 10 main body 11 crankshaft 12 cylinder block 13 cylinder head 14 intake valve drive system 15 exhaust valve drive system 16 spark plug 20 intake system 21 intake duct 22 air cleaner 23 air flow meter 24 air bypass valve 25 intercooler 26 throttle 26a pressure sensor 27 intake manifold 27a pressure sensor 28 tumble generator valve (TGV)
30 Exhaust system 31 Exhaust manifold 32 Exhaust pipe 33 Front catalyst 33a Front A/F sensor 33b Rear A/F sensor 34 Rear catalyst 35 Silencer 40 Turbocharger 41 Compressor 42 Turbine 43 Bearing housing 44 Wastegate valve 50 Fuel supply system 51 Fuel tank 52 Feed pump 53 Feed line 54 High-pressure pump 55 High-pressure fuel line 56 Injector 60 Evaporative fuel treatment system 61 Canister 61a Pipe 61b Fuel cut valve 62 Evaporative leak check module (ELCM)
63 Purge line 64 Purge line 64a Check valve 65 Purge line 66 Purge valve 67 Pressure sensor 68 Ejector 68a Inlet pipe 68b Nozzle 68c Discharge port 70 EGR device 71 EGR flow path 72 EGR cooler 73 EGR valve 100 Engine control unit (ECU)
101 accelerator pedal sensor 102 shift lever sensor 103 clutch switch 104 brake switch

Claims (2)

an engine having an air bypass valve that opens and closes an air bypass flow passage that connects an upstream side and a downstream side of a compressor of a turbocharger;
a transmission that changes the rotation output of the engine and performs a gear change operation of switching between a plurality of discretely set gear ratios;
a clutch provided between the engine and the transmission;
a gear shift operation detection unit that detects the start of a gear shift operation for changing the gear ratio in the transmission so as to reduce the reduction ratio;
a target speed calculation unit that calculates a target value of an output shaft rotation speed of the engine after the gear shift in response to a start of the gear shift operation;
an engine control unit that reduces the output shaft rotation speed of the engine to the target value in response to a start of the gear shift operation,
The transmission has a gear shift operation unit to which a gear shift operation by a driver is input,
the engine control unit opens the air bypass valve when the shift operation is detected after the clutch is disengaged while the output shaft rotation speed of the engine is decreasing , stops fuel injection into the engine while the air bypass valve is in the open state, and resumes fuel injection into the engine and closes the air bypass valve after the output shaft rotation speed reaches the target value and before the shift operation is completed, thereby maintaining the target value until the clutch is engaged.
A vehicle powertrain comprising: the transmission has an operation force sensor that detects an operation force applied to the gear shift operation unit by the driver and a direction in which the operation force is applied,
2. The vehicle powertrain according to claim 1 , wherein the target speed calculation unit calculates the target value based on a post-shift gear ratio estimated based on an output of the operating force sensor.

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