JP7239881B2 - vehicle system - Google Patents

Description

The present invention relates to a vehicle system that controls the posture of a vehicle according to steering.

2. Description of the Related Art Conventionally, there has been known a device (side slip prevention device, etc.) that controls the behavior of a vehicle in a safe direction when the behavior of the vehicle becomes unstable due to a slip or the like. Specifically, there is known a technology that detects the occurrence of understeer or oversteer behavior in the vehicle when the vehicle is cornering, etc., and applies appropriate deceleration to the wheels so as to suppress them. ing. In addition to such control for improving safety in a driving state where the behavior of the vehicle becomes unstable, control is applied to the vehicle when the steering wheel (hereinafter also simply referred to as "steering") is operated. There is known a technique for controlling a vehicle attitude by changing torque so that a driver's operation during cornering becomes natural and stable (see, for example, Patent Document 1). In particular, in the technique described in Patent Document 1, by controlling the ignition timing of the engine so as to change the torque according to the steering operation, more specifically, by retarding the ignition timing so as to reduce the torque, Controls vehicle attitude. Note that hereinafter, controlling the attitude of the vehicle in accordance with such steering operation may be referred to as "vehicle attitude control".

On the other hand, in recent years, premixed compression ignition combustion has been developed in which a mixture of air and gasoline fuel is burned by self-ignition in a sufficiently compressed cylinder. Moreover, partial compression ignition combustion, in which SI (Spark Ignition) combustion and CI (Compression Ignition) combustion are combined, is also proposed (see, for example, Patent Document 2). In this partial compression ignition combustion, spark ignition by a spark plug causes a part of the air-fuel mixture to be forcibly burned by flame propagation (SI combustion), and then the remaining unburned air-fuel mixture is burned by self-ignition (CI combustion). ). Hereinafter, such partial compression ignition combustion may be referred to as "SPCCI (SPark Controlled Compression Ignition) combustion" or "spark controlled compression ignition combustion".

JP 2017-96142 A WO2018/096744

There is a demand for executing vehicle attitude control in a vehicle having an engine capable of SPCCI combustion as described in Patent Document 2 above. However, if the ignition timing is changed for vehicle attitude control as in the technique described in Patent Document 1 while SPCCI combustion is being performed, SPCCI combustion may become unstable and misfire may occur. In particular, there is a combustion mode in which SPCCI combustion is performed by setting the air-fuel ratio of the air-fuel mixture to the lean side. Since it is lean, self-ignition (combustion) tends to be unstable.

The present invention has been made in order to solve the problems of the conventional technology described above. An object of the present invention is to provide a vehicle system capable of appropriately executing attitude control.

To achieve the above objectives, the present invention provides a rear wheel drive vehicle system having at least spark plugs, an engine in communication with the rear wheels, and a rotating electrical machine in communication with the rear wheels. , an operating state sensor for detecting the operating state of the engine, a steering wheel operated by the driver, a steering angle sensor for detecting the steering angle corresponding to the operation of the steering wheel, and a controller for controlling the engine and the rotary electric machine. , The engine has a combustion mode in which a part of the air-fuel mixture in the cylinder of the engine is burned by spark ignition with a spark plug, and then the remaining air-fuel mixture in the cylinder is burned by self-ignition, The controller sets the additional acceleration to be applied to the vehicle based on the steering angle detected by the steering angle sensor when the steering wheel is turned, and the driving condition sensor when the engine enters the combustion mode. Based on the detected operating state of the engine, the air-fuel ratio of the air-fuel mixture is set to either a first air-fuel ratio or a second air-fuel ratio that is leaner than the first air-fuel ratio, and the first air-fuel ratio is set. When the second air-fuel ratio is set, control the ignition timing of the spark plugs to cause additional acceleration to the vehicle, and control the ignition timing of the spark plugs to cause additional acceleration to the vehicle when the second air-fuel ratio is set. It is characterized in that it is configured to perform control to generate torque for driving the rear wheels.

In the present invention configured as described above, in realizing vehicle attitude control, when compression ignition combustion (especially SPCCI combustion) is performed at the first air-fuel ratio, the controller controls ignition in order to generate additional acceleration in the vehicle. While controlling the ignition timing of the plug, when compression ignition combustion is performed with a second air-fuel ratio that is leaner than the first air-fuel ratio, the rotary electric machine drives the rear wheels to generate additional acceleration in the vehicle. Control is performed to generate torque (driving torque) for driving. That is, when the second air-fuel ratio is set, the controller does not change the ignition timing of the engine, but performs torque assist by the rotary electric machine to generate additional acceleration in the vehicle. Accordingly, when performing compression ignition combustion in which the air-fuel ratio of the air-fuel mixture is set to the lean side, it is possible to appropriately perform vehicle attitude control while ensuring combustion stability.

In the present invention, preferably, the rotating electric machine is connected to the rear wheels via the winding member, and the controller suppresses regenerative power generation of the rotating electric machine when the second air-fuel ratio is set. It is configured.
According to the present invention configured in this way, the controller prohibits regenerative power generation by the rotary electric machine when the second air-fuel ratio is set. As a result, when the vehicle attitude control is performed while the second air-fuel ratio is being set, it is possible to suppress the delay in the torque assist of the rotary electric machine for the control. Specifically, by prohibiting regenerative power generation, the winding member connected to the rotating electric machine is always stretched in the direction of the torque assist side, so that when the second air-fuel ratio is set, vehicle attitude control is requested. In this case, the rotary electric machine can be quickly torque-assisted, and the desired vehicle attitude control can be properly realized.

In the present invention, the wrapping member is preferably a belt.
Since the belt has the property of being relatively stretchable, it takes time for the belt to be stretched in the direction of the torque assist side from the state of being stretched in the direction of the regeneration side. Therefore, in the present invention, when the winding member configured by the belt is applied, as described above, by prohibiting the regenerative power generation of the rotary electric machine when setting the second air-fuel ratio, the second air-fuel ratio is set. It is possible to effectively suppress the delay in the torque assist of the rotary electric machine when vehicle attitude control is performed at the time of setting.

In the present invention, the first air-fuel ratio is preferably the stoichiometric air-fuel ratio or an air-fuel ratio that is richer than the stoichiometric air-fuel ratio.
According to the present invention configured in this way, by setting the air-fuel ratio to be applied to the vicinity of the stoichiometric air-fuel ratio, it is possible to appropriately ensure the emission performance.

In the present invention, the second air-fuel ratio is preferably an air-fuel ratio leaner than the stoichiometric air-fuel ratio.
According to the present invention configured in this way, by setting the applied air-fuel ratio to be leaner than the stoichiometric air-fuel ratio, it is possible to appropriately secure fuel consumption performance and emission performance of the engine.

In the present invention, the second air-fuel ratio is preferably defined by the ratio of the amount of air to the amount of fuel in the air-fuel mixture, and this ratio is set within the range of 25-30.
According to the present invention configured in this way, the fuel consumption performance and emission performance of the engine can be effectively improved.

In the present invention, the controller is preferably configured to determine the steering speed from the steering angle detected by the steering angle sensor and set the additional acceleration based on the steering speed.
According to the present invention configured as described above, when performing vehicle attitude control, it is possible to appropriately add acceleration to the vehicle in accordance with the driver's steering operation.

According to the vehicle system of the present invention, when performing compression ignition combustion in which the air-fuel ratio of the air-fuel mixture is set to the lean side, it is possible to appropriately perform vehicle attitude control while ensuring combustion stability.

1 is a block diagram showing the overall configuration of a vehicle to which a vehicle system according to an embodiment of the invention is applied; FIG. 1 is a schematic configuration diagram of an engine according to an embodiment of the present invention; FIG. 1 is a block diagram showing a control configuration of a vehicle system according to an embodiment of the invention; FIG. FIG. 4 is an explanatory diagram of an operating range of the engine according to the embodiment of the present invention; FIG. 4 is an explanatory diagram of a mechanism of vehicle attitude control according to the embodiment of the present invention; 4 is a flow chart showing overall control according to an embodiment of the present invention; 4 is a flowchart showing motor generator setting processing according to the embodiment of the present invention; 4 is a flowchart showing increased torque setting processing according to the embodiment of the present invention; 4 is a map showing the relationship between additional acceleration and steering speed according to an embodiment of the present invention; 4 is a flowchart showing increased torque application processing according to the embodiment of the present invention; An example of a time chart when vehicle attitude control is executed according to the embodiment of the present invention is shown. 4 shows another example of a time chart when vehicle attitude control is executed according to the embodiment of the present invention;

A vehicle system according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

<Vehicle configuration>
FIG. 1 is a block diagram showing the overall configuration of a vehicle to which a vehicle system according to an embodiment of the invention is applied. As shown in FIG. 1, a vehicle 100 according to this embodiment is an FR drive vehicle and includes an engine 1 as a main drive source. For example, the engine 1 is an in-line four-cylinder gasoline engine that has four cylinders (not shown) and is capable of SI combustion and SPCCI (partial compression ignition combustion/spark ignition controlled compression ignition combustion).

A vehicle 100 includes a vehicle body 101 on which an engine 1 and the like are mounted, front wheels 102 as driven wheels and steering wheels, and rear wheels 103 as driving wheels. The front wheels 102 and the rear wheels 103 are respectively supported by suspensions 120 with respect to the vehicle body 101 . Driving force generated by engine 1 is transmitted to rear wheels 103 via transmission 110, propeller shaft 116, rear differential gear 118, and the like. The vehicle 100 also includes a steering device 104 including a steering wheel (steering) 105 and a steering shaft 106 for steering the front wheels 102, and an accelerator pedal 107 operated by the driver.

The vehicle 100 also has a motor generator 114 that has a function of driving the rear wheels 103 (that is, a function as an electric motor) and a function that is driven by the rear wheels 103 to regenerate power (that is, a function as a generator). is installed. Specifically, motor generator 114 transmits power to rear wheel 103 via rubber belt 112 as a winding member, engine 1, transmission 110, and the like. The motor generator 114 is connected to a battery (not shown), is supplied with electric power from the battery when generating drive torque, and is supplied with electric power to charge the battery when generating (regenerating) power.

Further, the vehicle 100 is equipped with a controller 60 (controller). The controller 60 controls the engine 1, the motor generator 114, etc., based on detection signals output from various sensors in the vehicle 100. FIG. Strictly speaking, controller 60 controls motor generator 114 via an inverter (not shown).

<Engine configuration>
FIG. 2 is a schematic configuration diagram of an engine according to an embodiment of the present invention. The engine 1 comprises an engine body 1a composed of a 4-cycle gasoline direct injection engine, an intake passage 30 through which intake air introduced into the engine body a flows, and an exhaust passage 40 through which exhaust gas discharged from the engine body 1a flows. , and an EGR device 50 for recirculating part of the exhaust gas flowing through the exhaust passage 40 to the intake passage 30 .

Engine 1 is used as a drive source for vehicle 100 . In this embodiment, the engine 1 is an engine that is driven by being supplied with fuel containing gasoline as a main component. Note that the fuel may be gasoline containing bioethanol or the like. The engine body 1 a includes a cylinder block 3 , a cylinder head 4 and pistons 5 . The cylinder block 3 has cylinder liners that form the four cylinders described above. The cylinder head 4 is attached to the upper surface of the cylinder block 3 and closes the upper opening of the cylinder 2 . A piston 5 is housed in each cylinder 2 so as to be reciprocally slidable, and is connected to a crankshaft 7 via a connecting rod 8 . As the piston 5 reciprocates, the crankshaft 7 rotates about its central axis.

A combustion chamber 6 is formed above the piston 5 . Fuel is supplied to the combustion chamber 6 by injection from an injector 15, which will be described later. Then, the mixture of the supplied fuel and air is combusted in the combustion chamber 6, and the piston 5, which is pushed down by the expansion force due to the combustion, reciprocates in the vertical direction. The geometric compression ratio of the cylinder 2, that is, the ratio between the volume of the combustion chamber 6 when the piston 5 is at top dead center and the volume of the combustion chamber 6 when the piston 5 is at bottom dead center, is determined by SPCCI combustion, which will be described later. is set to a high compression ratio of 13 or more and 30 or less (for example, about 20) so as to be suitable for

A crank angle sensor SN1 and a water temperature sensor SN2 are attached to the cylinder block 3 . The crank angle sensor SN1 detects the rotation angle (crank angle) of the crankshaft 7 and the rotation speed of the crankshaft 7 (engine rotation speed). The water temperature sensor SN2 detects the temperature of cooling water (engine water temperature) flowing inside the cylinder block 3 and the cylinder head 4 .

An intake port 9 and an exhaust port 10 communicating with the combustion chamber 6 are formed in the cylinder head 4 . The bottom surface of the cylinder head 4 serves as the ceiling surface of the combustion chamber 6 . An intake side opening that is the downstream end of the intake port 9 and an exhaust side opening that is the upstream end of the exhaust port 10 are formed in the ceiling surface of the combustion chamber. The cylinder head 4 is assembled with an intake valve 11 that opens and closes an intake side opening and an exhaust valve 12 that opens and closes an exhaust side opening. Although illustration is omitted, the engine main body 1a has a four-valve format of two intake valves and two exhaust valves, and two intake ports 9 and two exhaust ports 10 are provided for each cylinder 2. In addition, two intake valves 11 and two exhaust valves 12 are also provided.

The cylinder head 4 is provided with an intake-side valve mechanism 13 and an exhaust-side valve mechanism 14 including camshafts. The intake valve 11 and the exhaust valve 12 are driven to open and close by these valve mechanisms 13 and 14 in conjunction with the rotation of the crankshaft 7 . The intake valve mechanism 13 incorporates an intake VVT 13 a capable of changing at least the opening timing of the intake valve 11 . Similarly, the exhaust side valve mechanism 14 incorporates an exhaust VVT 14a capable of changing at least the closing timing of the exhaust valve 12 . By controlling these intake VVT 13a and exhaust VVT 14a, it is possible to adjust the valve overlap period during which both the intake valve 11 and the exhaust valve 12 are opened across the exhaust top dead center. Further, by adjusting the valve overlap period, it is possible to adjust the amount of burned gas (internal EGR gas) remaining in the combustion chamber 6 .

An injector 15 (fuel injection valve) and a spark plug 16 are further attached to the cylinder head 4 . The injector 15 injects fuel into the cylinder 2 (combustion chamber 6). As the injector 15, it is possible to use a multi-hole type injector that has a plurality of injection holes at its tip and is capable of radially injecting fuel from these injection holes. The injector 15 is arranged such that its tip is exposed in the combustion chamber 6 and faces the radial center of the crown surface of the piston 5 .

The spark plug 16 is arranged at a position slightly shifted toward the intake side with respect to the injector 15 , and is arranged at a position where the tip portion (electrode portion) thereof faces the inside of the cylinder 2 . The spark plug 16 is a forced ignition source that ignites a mixture of fuel and air formed in the cylinder 2 (combustion chamber 6).

The cylinder head 4 is provided with an in-cylinder pressure sensor SN3, an intake cam angle sensor SN12, and an exhaust cam angle sensor SN13 as sensing elements. An in-cylinder pressure sensor SN3 detects the pressure in the combustion chamber 6 . The intake cam angle sensor SN12 detects the rotational position of the camshaft of the intake side valve mechanism 13, and the exhaust cam angle sensor SN13 detects the rotational position of the exhaust side valve mechanism 14, respectively.

The intake passage 30 is connected to one side surface of the cylinder head 4 so as to communicate with the intake port 9, as shown in FIG. Air (fresh air) taken from the upstream end of the intake passage 30 is introduced into the combustion chamber 6 through the intake passage 30 and the intake port 9 . An air cleaner 31 , a throttle valve 32 , a supercharger 33 , an electromagnetic clutch 34 , an intercooler 35 and a surge tank 36 are arranged in the intake passage 30 in this order from the upstream side.

The air cleaner 31 cleans the intake air by removing foreign substances in the intake air. The throttle valve 32 opens and closes the intake passage 30 in conjunction with the depression of the accelerator pedal 107 to adjust the flow rate of intake air in the intake passage 30 . The supercharger 33 compresses the intake air and sends the intake air to the downstream side of the intake passage 30 . The supercharger 33 is a supercharger mechanically linked to the engine body 1a, and is switched between engagement and disengagement with the engine body 1a by an electromagnetic clutch 34 . When the electromagnetic clutch 34 is engaged, the driving force is transmitted from the engine body 1a to the supercharger 33, and supercharging by the supercharger 33 is performed. The intercooler 35 cools the intake air compressed by the supercharger 33 . The surge tank 36 is a tank that is arranged immediately upstream of an intake manifold (not shown) and provides a space for evenly distributing the intake air to the plurality of cylinders 2 .

Each portion of the intake passage 30 includes an air flow sensor SN4 for detecting the flow rate of intake air, first and second intake air temperature sensors SN5 and SN7 for detecting the temperature of the intake air, and first and second intake air temperature sensors for detecting the pressure of the intake air. Air pressure sensors SN6 and SN8 are provided. An airflow sensor SN4 and a first intake air temperature sensor SN5 are arranged in a portion between the air cleaner 31 and the throttle valve 32 in the intake passage 30, and detect the flow rate and temperature of intake air passing through that portion, respectively. The first intake pressure sensor SN6 is provided in a portion of the intake passage 30 between the throttle valve 32 and the supercharger 33 (downstream of a connection port of the EGR passage 51, which will be described later). Detect pressure. The second intake air temperature sensor SN7 is provided in a portion between the supercharger 33 and the intercooler 35 in the intake passage 30, and detects the temperature of the intake air passing through that portion. A second intake pressure sensor SN8 is provided in the surge tank 36 and detects the pressure of intake air in the surge tank 36 .

The intake passage 30 is provided with a bypass passage 38 for bypassing the supercharger 33 and sending intake air to the combustion chamber 6 . The bypass passage 38 connects the surge tank 36 and the vicinity of the downstream end of the EGR passage 51 to be described later. A bypass valve 39 capable of opening and closing the bypass passage 38 is provided in the bypass passage 38 .

The exhaust passage 40 is connected to the other side surface of the cylinder head 4 so as to communicate with the exhaust port 10 . Burned gas (exhaust gas) generated in the combustion chamber 6 is discharged outside the vehicle 100 through the exhaust port 10 and the exhaust passage 40 . A catalytic converter 41 is provided in the exhaust passage 40 . The catalytic converter 41 includes a three-way catalyst 41a for purifying harmful components (HC, CO, NOx) contained in the exhaust gas flowing through the exhaust passage 40, and particulate matter (PM) contained in the exhaust gas. A GPF (gasoline particulate filter) 41b for collecting is incorporated.

The EGR device 50 includes an EGR passage 51 connecting the exhaust passage 40 and the intake passage 30 , and an EGR cooler 52 and an EGR valve 53 provided in the EGR passage 51 . The EGR passage 51 connects a portion of the exhaust passage 40 downstream of the catalytic converter 41 and a portion of the intake passage 30 between the throttle valve 32 and the supercharger 33 . The EGR cooler 52 cools the exhaust gas (external EGR gas) recirculated from the exhaust passage 40 to the intake passage 30 through the EGR passage 51 by heat exchange. The EGR valve 53 is provided in the EGR passage 51 on the downstream side of the EGR cooler 52 so as to be openable and closable, and adjusts the flow rate of the exhaust gas flowing through the EGR passage 51 . The EGR passage 51 is provided with a differential pressure sensor SN9 for detecting the difference between the pressure on the upstream side and the pressure on the downstream side of the EGR valve 53 .

The accelerator pedal 107 is provided with an accelerator opening sensor SN10 for detecting the accelerator opening. The accelerator opening sensor SN10 is a sensor that detects the degree of depression of the accelerator pedal 107, and is also a sensor that detects acceleration and deceleration of the driver. A steering angle sensor SN11 is attached to the steering wheel 105 . Steering angle sensor SN11 detects the steering angle of front wheels 102 by steering 105 . Note that another steering angle sensor capable of detecting the steering angle of the front wheels 102 (for example, a sensor that detects the turning angle (tire angle) of the front wheels 102, etc.) may be applied.

<Control configuration>
FIG. 3 is a block diagram showing the control configuration of the vehicle system according to the embodiment of the invention. As shown in FIG. 3, the controller 60 is a controller based on a well-known microcomputer, and includes a microprocessor as a central processing unit (CPU) for executing programs, and a RAM (Random Access Memory), for example. Memory) and ROM (Read Only Memory) for storing programs and data, and an input/output bus for inputting/outputting electrical signals.

Detection signals from various sensors mounted on the vehicle 100 are input to the controller 60 . The controller 60 controls the above-mentioned crank angle sensor SN1, water temperature sensor SN2, in-cylinder pressure sensor SN3, air flow sensor SN4, first and second intake air temperature sensors SN5 and SN7, first and second intake pressure sensors SN6 and SN8, differential pressure In addition to sensor SN9, accelerator opening sensor SN10, steering angle sensor SN11, intake cam angle sensor SN12 and exhaust cam angle sensor SN13, it is electrically connected to vehicle speed sensor SN14. Information detected by these sensors SN1 to SN14, that is, crank angle, engine speed, engine water temperature, cylinder pressure, intake flow rate, intake temperature, intake pressure, differential pressure across EGR valve 53, accelerator opening, steering Information such as cam angle, intake/exhaust cam angle, vehicle speed, etc. are sequentially input to the controller 60 .

The controller 60 controls each section of the engine while executing various determinations and calculations based on input signals from the sensors SN1 to SN14 and others. That is, the controller 60 is electrically connected to the intake VVT 13a, the exhaust VVT 14a, the injector 15, the spark plug 16, the throttle valve 32, the electromagnetic clutch 34, the bypass valve 39, the EGR valve 53, the motor generator 114, and the like. Control signals are output to each of these devices based on the results of calculations and the like.

Note that in the above-described embodiment, the vehicle system in the present invention mainly includes the engine 1, the motor generator 114 as a rotating electric machine, the crank angle sensor SN1 and the accelerator opening sensor SN10 as driving state sensors, and the like. It is composed of a steering wheel 105, a steering angle sensor SN11, and a controller 60 as a controller.

<Combustion control>
Next, combustion control of the engine 1 according to this embodiment will be described in detail. FIG. 4 is an explanatory diagram of the operating range of the engine 1 according to the embodiment of the invention. Specifically, FIG. 4 is a simple operation map for explaining differences in combustion control according to engine speed and load. This operating map shows four operating areas: a first area A1, a second area A2, a third area A3 and a fourth area A4. The first area A1 is a low load area (including no load) in which the engine load is low (including no load) in a low/medium engine speed area, and a medium load/high load area in a high engine speed area. . The second area A2 is a low/medium speed area with a higher load than the first area A1 (low/medium speed/medium load area). The third area A3 is a low/medium speed area in which the load is higher than that of the second area A2 (low/medium speed/high load area). The fourth area A4 is an area close to the full open line in the low speed area.

SI combustion is performed in the first area A1 and the fourth area A4. In SI combustion, the air-fuel mixture in the combustion chamber 6 is ignited by spark ignition using the spark plug 16, and the flame propagation that spreads the combustion area from the ignition point to the surroundings forces the air-fuel mixture to burn. form. That is, the SI combustion is a combustion mode in which all of the air-fuel mixture in the cylinder 2 is combusted by propagation of the flame generated by the spark plug 16 .

SPCCI combustion (partial compression ignition combustion/spark ignition controlled compression ignition combustion) is performed in the second region A2 and the third region A3. SPCCI combustion is combustion in which the above SI combustion and CI combustion are mixed. CI combustion is a combustion mode in which an air-fuel mixture is combusted by self-ignition under an environment of high temperature and high pressure due to compression of the piston 5 . In the SPCCI combustion, part of the air-fuel mixture in the combustion chamber 6 is SI-burned by spark ignition performed in an environment just before the air-fuel mixture self-ignites. This is a combustion mode in which the remaining air-fuel mixture in the combustion chamber 6 is CI-burned by self-ignition. That is, SPCCI combustion is a combustion mode in which at least part of the air-fuel mixture in cylinder 2 is combusted by self-ignition.

The SPCCI combustion according to the present embodiment is a combustion mode (hereinafter referred to as " and a combustion mode in which the air-fuel ratio of the air-fuel mixture formed in the combustion chamber 6 is set to an air-fuel ratio (second air-fuel ratio) that is leaner than the stoichiometric air-fuel ratio (hereinafter referred to as the “first combustion mode”). 2 combustion modes"). Specifically, in the first combustion mode, the air-fuel ratio (A/F), which is the weight ratio of air (fresh air) and fuel in the combustion chamber 6, is set to the theoretical air-fuel ratio (λ=1) or its vicinity (λ< 1) is set and SPCCI combustion is performed. Needless to say, the air-fuel ratio A/F in the first combustion mode is 14.7/1 at λ=1. On the other hand, the second combustion mode is a mode in which SPCCI combustion is performed while setting the air-fuel ratio (A/F) to a value greater than the stoichiometric air-fuel ratio (14.7). In this embodiment, the air-fuel ratio A/F of the air-fuel mixture formed in the second combustion mode is set in the range of approximately 25 to 30/1. At the time of SPCCI combustion, either the second combustion mode (λ>1) or the first combustion mode (λ≦1) is selected based on the operating state of the engine 1 (basically, the rotation speed and the accelerator opening). selected by

First, in the second region A2, combustion in the second combustion mode (λ>1) of SPCCI combustion is performed. The combustion control executed by the controller 60 in this second area A2 is as follows. The controller 60 causes the injector 15 to inject fuel in two stages, a fuel injection (first time) and a fuel injection (second time), from the middle to the latter half of the compression stroke. Further, the controller 60 causes the ignition plug 16 to ignite the air-fuel mixture at a timing close to the top dead center of the compression stroke and slightly advanced. Triggered by this ignition, SPCCI combustion is started, a part of the air-fuel mixture in the combustion chamber 6 burns due to flame propagation (SI combustion), and then the remaining air-fuel mixture burns due to self-ignition (CI combustion).

The advantages of SPCCI combustion will now be described. SPCCI combustion has the property that heat generation becomes steeper when CI combustion occurs than when SI combustion occurs. That is, the slope of the rise at the beginning of combustion corresponding to SI combustion is smaller than the slope of rise corresponding to subsequent CI combustion. When the temperature and pressure in the combustion chamber 6 increase due to SI combustion, the unburned air-fuel mixture self-ignites and CI combustion starts. At the timing when this CI combustion starts, the slope of the waveform of the heat release rate changes from low to high. Further, in response to such a tendency of the heat release rate, in SPCCI combustion, the pressure rise rate (dp/dθ) in the combustion chamber 6 occurring during SI combustion is smaller than that during CI combustion.

After the start of CI combustion, SI combustion and CI combustion are performed in parallel. In CI combustion, the combustion speed of air-fuel mixture is faster than in SI combustion, so the heat generation rate is relatively large. However, since CI combustion occurs after compression top dead center, the slope of the heat release rate waveform does not become excessive. That is, when the compression top dead center is passed, the motoring pressure drops due to the descent of the piston 5, which suppresses the rise in the heat release rate, thereby avoiding an excessive increase in dp/dθ during CI combustion. be. In this way, in SPCCI combustion, CI combustion is performed after SI combustion. ), combustion noise can be suppressed.

SPCCI combustion also ends with the end of CI combustion. Since the CI combustion has a higher combustion speed than the SI combustion, it is possible to advance the combustion end timing as compared to the simple SI combustion (when all the fuel is SI-burned). In other words, in SPCCI combustion, the end of combustion can be brought closer to compression top dead center in the expansion stroke. As a result, SPCCI combustion can improve fuel efficiency compared to simple SI combustion.

Next, in the low load region within the third region A3, the SPCCI combustion falls under the first combustion mode (λ≤1), and the air-fuel ratio in the combustion chamber 6 reaches the stoichiometric air-fuel ratio (λ = 1). Combustion of the prepared air-fuel mixture is performed. In this case, the controller 60 causes the injector 15 to perform the first fuel injection in which a relatively large amount of fuel is injected during the intake stroke, and then the second fuel injection in which a smaller amount of fuel is injected than the first fuel injection. fuel injection is performed during the compression stroke. Further, the controller 60 causes the ignition plug 16 to ignite the air-fuel mixture at a timing slightly advanced from the compression top dead center. This ignition triggers the start of SPCCI combustion, which is the same as in the above-described second combustion mode.

Further, in the high load region of the third region A3, which falls within the category of the first combustion mode of the SPCCI combustion, the air-fuel ratio in the combustion chamber 6 is slightly richer than the stoichiometric air-fuel ratio (λ≤1). Combustion of the air-fuel mixture is performed. In this case, the controller 60 causes the injector 15 to inject all or most of the fuel to be injected during one cycle during the intake stroke. For example, fuel is injected over a series of periods from the latter half of the intake stroke to the beginning of the compression stroke. Further, the controller 60 causes the ignition plug 16 to ignite the air-fuel mixture at a timing near the compression top dead center and on the slightly retarded side. This ignition triggers the start of SPCCI combustion, which is the same as in the above-described second combustion mode and the like.

In addition, in the third region A3, an example in which the air-fuel mixture is formed at the stoichiometric air-fuel ratio λ=1 and the case in which the air-fuel mixture is formed at a slightly richer λ≦1 than the stoichiometric air-fuel ratio is used according to the load. However, instead of this, the air-fuel mixture may be formed at the stoichiometric air-fuel ratio of λ=1 throughout the third region A3.

On the other hand, in the fourth region A4, SI combustion with retarded ignition timing is executed instead of SPCCI combustion. In this case, the controller 60 causes the injector 15 to perform the first fuel injection of a relatively large amount of fuel during the intake stroke, and then inject a smaller amount of fuel than the first fuel injection. The first fuel injection is executed late in the compression stroke (immediately before compression top dead center). Also, the controller 60 causes the ignition plug 16 to perform retarded ignition. The ignition timing of the air-fuel mixture is, for example, a relatively late timing after about 5 to 20° CA has passed from the top dead center of the compression stroke. This ignition triggers SI combustion, and all of the air-fuel mixture in the combustion chamber 6 burns due to flame propagation. The reason why the ignition timing in the fourth region A4 is retarded as described above is to prevent abnormal combustion such as knocking and pre-ignition.

Also in the first region A1, orthodox SI combustion is executed instead of SPCCI combustion. In this case, controller 60 causes injector 15 to inject fuel over a series of periods from the intake stroke to the compression stroke. Further, the controller 60 causes the ignition plug 16 to ignite the air-fuel mixture at a timing slightly advanced from the compression top dead center. This ignition triggers SI combustion, and all of the air-fuel mixture in the combustion chamber 6 burns due to flame propagation.

<Vehicle attitude control>
Next, vehicle attitude control executed by the controller 60 in this embodiment will be described.

First, an outline of vehicle attitude control according to the present embodiment will be described. In this embodiment, the controller 60 operates based on the steering angle detected by the steering angle sensor SN11 (more specifically, based on the steering speed obtained from the steering angle) when the steering wheel (steering) 105 is turned. ), an additional acceleration to be applied to the vehicle 100 is set, and an increase torque is set for increasing the torque applied to the vehicle 100 in order to generate this additional acceleration. By increasing the torque applied to the vehicle 100 in accordance with such increased torque, acceleration (additional acceleration) is generated in the vehicle 100, thereby improving the turning responsiveness of the vehicle 100 to the turning operation of the steering wheel 105. be able to.

Now, with reference to FIG. 5, the vehicle attitude control mechanism according to the embodiment of the present invention will be described. As shown in FIG. 5, when the torque of the rear wheels 103 increases in response to the application of the increased torque described above, a force F1 that propels the rear wheels 103 forward of the vehicle is transferred from the rear wheels 103 to the vehicle body 101 via the suspension 120. transmitted. In this case, since the suspension 120 extends obliquely upward from the central axis 103a of the rear wheel 103 toward the mounting portion 120a of the vehicle body 101 (the mounting portion 120a is the actual mounting portion of the suspension 120 to the vehicle body 101). Rather, it means a point at which the force from the rear wheel 103 acts on the vehicle body 101, that is, a virtual point of action. means an imaginary line segment connecting the central axis 103a of the wheel 103), the force F11, which is the upward component of the force F1 that propels the rear wheel 103 forward of the vehicle, is generated in the vehicle body 101. A force F11 that lifts the rear portion of the vehicle body 101 upward acts on the vehicle body 101 momentarily. As a result, a moment Y1 is generated as shown in FIG. A force F12 that causes the front portion of the vehicle body 101 to sink downward acts on the vehicle body 101 due to the moment Y1 in the direction that generates pitching in the forward tilting direction, and the front portion of the vehicle body 101 sinks, increasing the load on the front wheels. do. As a result, the turning responsiveness of the vehicle 100 to the turning operation of the steering wheel 105 can be improved.
When the torque of the rear wheels 103 is increased as described above, it is conceivable that an inertial force that tilts the vehicle body 101 backward is generated in addition to the momentary force that tilts the vehicle body 101 forward. The instantaneous forward leaning force of the vehicle body 101 due to the torque increase of the rear wheels 103 predominantly contributes to the vehicle responsiveness to the operation.

Furthermore, in the present embodiment, the controller 60 is controlled when the first combustion mode of the SPCCI combustion is performed (that is, when the SPCCI combustion in which the stoichiometric air-fuel ratio or the first air-fuel ratio richer than the stoichiometric air-fuel ratio is set is performed) ) and when the second combustion mode of the SPCCI combustion is performed (that is, when the SPCCI combustion in which the second air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio is performed), additional acceleration is generated in the vehicle 100. Change the control mode for Specifically, the controller 60 controls the ignition timing of the spark plug 16 to generate additional acceleration in the vehicle 100 in the first combustion mode, while generating additional acceleration in the vehicle 100 in the second combustion mode. In order to achieve this, control is performed to generate drive torque (torque for driving the rear wheels 103) from the motor generator 114. FIG. That is, in the first combustion mode, the controller 60 advances the ignition timing (in this case, the torque of the engine 1 increases), thereby increasing the torque applied to the vehicle 100, thereby realizing additional acceleration. On the other hand, in the second combustion mode, motor generator 114 generates driving torque (in this case, motor generator 114 assists engine 1 with torque), so that the torque applied to vehicle 100 is reduced. By increasing it, additional acceleration is realized.

If the ignition timing is advanced in the second combustion mode in which the air-fuel ratio is set to the lean side, the SPCCI combustion tends to become unstable because the air-fuel mixture is lean. Therefore, in the present embodiment, in the second combustion mode, the controller 60 causes the motor generator 114 to generate a drive torque instead of advancing the ignition timing, that is, the motor generator 114 performs torque assist to provide additional acceleration. is generated in the vehicle 100 . By doing so, it becomes possible to appropriately execute vehicle attitude control while ensuring the combustion stability of the SPCCI combustion in which the air-fuel ratio is set to the lean side.

In the vehicle attitude control, basically, the amount of intake air introduced into the engine 1 is controlled (the throttle valve 32 and the intake valve 11 However, since this control involves a relatively large delay, the ignition timing is controlled to compensate for this delay. That is, as a result, by advancing the ignition timing and increasing the torque of the engine 1, the vehicle attitude control is realized. On the other hand, SPCCI combustion is basically realized by controlling the air amount, EGR amount, fuel injection amount, fuel injection timing, etc., but these controls are also accompanied by delays. As such, the ignition timing is consequently controlled to compensate for this delay. Therefore, if the ignition timing is controlled for vehicle attitude control when performing SPCCI combustion, the ignition timing for SPCCI combustion cannot be controlled, and appropriate SPCCI combustion may not be realized. Such a problem becomes particularly conspicuous in SPCCI combustion (second combustion mode) in which the air-fuel ratio is set on the lean side. This is because self-ignition (combustion) tends to be unstable because the air-fuel mixture is lean. Therefore, in this embodiment, when the vehicle attitude control is performed in the second combustion mode of the SPCCI combustion, the controller 60 performs torque assist by the motor generator 114 instead of advancing the ignition timing as described above. , an additional acceleration is generated in the vehicle 100 .

However, in SPCCI combustion (first combustion mode) in which the air-fuel ratio is set to the stoichiometric air-fuel ratio or to the rich side of the stoichiometric air-fuel ratio, even if the ignition timing is controlled for vehicle attitude control during the SPCCI combustion, as described above, In other words, the combustion stability of SPCCI combustion is ensured. This is because the air-fuel ratio of the air-fuel mixture satisfies λ≦1, so that self-ignition is likely to occur, that is, combustion is likely to be stable. Also, with respect to SI combustion, it goes without saying that even if the ignition timing is controlled for vehicle attitude control during the combustion, the above-described problems do not occur. Therefore, in the present embodiment, the controller 60 generates additional acceleration to the vehicle 100 by advancing the ignition timing as usual when performing vehicle attitude control during the first combustion mode of the SPCCI combustion and during the SI combustion. let them

Furthermore, in this embodiment, the controller 60 prohibits regenerative power generation by the motor generator 114 in the second combustion mode. The reason for this is as follows. When the motor generator 114 regenerates power, the belt 112 connected to the motor generator 114 is stretched in one direction (the regeneration side opposite to the torque assist side), that is, the belt 112 extends toward the regeneration side. . In such a state of the belt 112, if the vehicle attitude is controlled by the torque assist of the motor generator 114 in the second combustion mode, the torque assist by the motor generator 114 tends to be delayed. This is because it takes time for the belt 112 to be stretched in the direction of the torque assist side opposite to the regeneration side from the state of being stretched in the direction of the regeneration side. Therefore, in the present embodiment, controller 60 prohibits regenerative power generation by motor generator 114 in the second combustion mode in order to suppress a delay in torque assist of motor generator 114 for vehicle attitude control. That is, in the second combustion mode, regenerative power generation by the motor generator 114 is prohibited, and the belt 112 is moved toward the torque assist side of the motor generator 114 in order to ensure proper vehicle attitude control in the second combustion mode. always keep it stretched (stretched).

Next, the vehicle attitude control according to this embodiment will be specifically described with reference to FIGS. 6 to 10. FIG. FIG. 6 is a flow chart showing overall control according to an embodiment of the present invention. FIG. 7 is a flow chart showing motor generator setting processing according to the embodiment of the present invention, which is executed in the overall control of FIG. 8 is a flowchart showing torque increase setting processing according to an embodiment of the present invention, which is executed in the overall control of FIG. 6, and FIG. 9 is an embodiment of the present invention used in the torque increase setting processing of FIG. 4 is a map showing the relationship between additional acceleration and steering speed. FIG. 10 is a flow chart showing increased torque application processing according to the embodiment of the present invention, which is executed in the overall control of FIG.

The control process of FIG. 6 is started when the ignition of the vehicle 100 is turned on and the controller 60 is powered on, and is repeatedly executed at a predetermined cycle (for example, 50 ms). When this control process is started, the controller 60 acquires various sensor information in step S11. Specifically, the controller 60 acquires sensor information corresponding to the detection signals output by the sensors SN1 to SN14 described above. In particular, the controller 60 detects the steering angle detected by the steering angle sensor SN11, the accelerator opening detected by the accelerator opening sensor SN10, the vehicle speed detected by the vehicle speed sensor SN14, the engine speed detected by the crank angle sensor SN1, and the vehicle The gear position currently set in the transmission 110 of 100 is acquired.

Next, in step S12, the controller 60 sets a control command value for the engine 1 based on the various sensor information acquired in step S11. First, the controller 60 sets a target acceleration based on the vehicle speed, accelerator opening, and the like. In one example, the controller 60 selects an acceleration characteristic map (created in advance and stored in a memory or the like) defined for various vehicle speeds and various gear stages, and selects a map corresponding to the current vehicle speed and gear stage. Select the acceleration characteristic map, and refer to the selected acceleration characteristic map to set the target acceleration corresponding to the current accelerator opening. The controller 60 then determines the target torque that the engine 1 should generate in order to achieve this target acceleration. In this case, the controller 60 determines the target torque within the range of torque that the engine 1 can output based on the current vehicle speed, gear stage, road surface gradient, road surface μ, and the like. Further, the controller 60 refers to the operation map shown in FIG. 4, selects a region corresponding to the current engine load and engine speed from among the regions A1 to A4, and performs combustion control according to the region. (Control for SI combustion and SPCCI combustion (including first and second combustion modes)). The controller 60 controls each component of the engine 1 (the intake VVT 13a, the exhaust VVT 14a, the injector 15, the spark plug 16, the throttle valve 32, the electromagnetic clutch 34, the bypass valve) so as to achieve this combustion control and the above-described target torque. 39, to set the control command value for the EGR valve 53).

Next, at step S13, the controller 60 executes the motor generator setting process shown in FIG.

As shown in FIG. 7, when the motor generator setting process is started, controller 60 sets a control command value for motor generator 114 in step S21. Specifically, the controller 60 sets the above-described target torque based on the efficiency of the engine 1, the efficiency of the motor generator 114, and the state of charge (SOC) of the battery that transfers electric power to and from the motor generator 114. A control command value for the motor generator 114 is set. In this case, the controller 60 refers to, for example, a predetermined efficiency map of the engine 1 and an efficiency map of the motor generator 114 (including both drive (powering) and regeneration efficiencies). The controller 60 controls the motor generator 114 so as to operate both the engine 1 and the motor generator 114 as efficiently as possible and generate the target torque from the vehicle 100 while complying with the input/output limit according to the SOC of the battery. Set the command value. The controller 60 preferably changes the control command value for the engine 1 set in step S12 based on the control command value for the motor generator 114 thus set.

Next, in step S22, the controller 60 determines whether or not the combustion mode of the engine 1 is set to the second combustion mode. For example, the controller 60 determines the current combustion mode of the engine 1 based on the operation map shown in FIG. 4 and the current operating state of the engine 1 (engine load and engine speed).

As a result of step S22, when it is determined that the second combustion mode is set (step S22: Yes), the controller 60 proceeds to step S23, permits torque assist of the motor generator 114, and prohibits regenerative power generation. . Controller 60 prohibits execution of regenerative power generation even if there is a request for regenerative power generation of motor generator 114 from another control or process thereafter. The reason for prohibiting regenerative power generation in this way is to suppress delays in the torque assist of motor generator 114 for control when vehicle attitude control is performed in the second combustion mode, as described above. . That is, by prohibiting regenerative power generation, the belt 112 connected to the motor generator 114 is always stretched in the direction of the torque assist side (stretched), so that during the second combustion mode This is to ensure the realization of appropriate vehicle attitude control. After such step S23, the controller 60 ends the motor generator setting process and returns to the main routine of FIG.

On the other hand, if it is determined that the second combustion mode is not set (step S22: No), that is, if the first combustion mode is set or SI combustion is being performed, the controller 60 , the process proceeds to step S24, and permits both torque assist and regenerative power generation of the motor generator 114 as usual. After step S24, the controller 60 ends the motor generator setting process and returns to the main routine of FIG.

Returning to FIG. 6, after the motor generator setting process (step S13), the controller 60 proceeds to step S14 and executes the increased torque setting process shown in FIG.

As shown in FIG. 8, when the increased torque setting process is started, in step S31, the controller 60 determines whether the steering angle (absolute value) of the steering device 104 is increasing, that is, whether the steering wheel 105 is turned. Determine whether or not As a result, when it is determined that the steering angle is increasing (step S31: Yes), the controller 60 proceeds to step S32 and determines whether or not the steering speed is equal to or greater than a predetermined threshold value _S1 . In this case, the controller 60 calculates the steering speed based on the steering angle acquired from the steering angle sensor SN11 in step S11 of FIG. 6, and determines whether or not the calculated value is equal to or greater than the threshold value _S1 .

As a result of step S32, when it is determined that the steering speed is equal to or greater than the threshold _S1 (step S32: Yes), the process proceeds to step S33, and the controller 60 sets additional acceleration based on the steering speed. This additional acceleration is acceleration that should be applied to the vehicle 100 according to the steering operation in order to control the vehicle posture in accordance with the driver's intention.

Specifically, the controller 60 sets the additional acceleration corresponding to the steering speed calculated in step S32 based on the relationship between the additional acceleration and the steering speed shown in the map of FIG. The horizontal axis in FIG. 9 indicates the steering speed, and the vertical axis indicates the additional acceleration. As shown in FIG. 9, when the steering speed is less than or equal to threshold _S1 , the corresponding additional acceleration is zero. That is, when the steering speed is equal to or less than the threshold _S1 , the controller 60 does not perform control for adding acceleration to the vehicle 100 based on the steering operation.

On the other hand, when the steering speed exceeds the threshold value _S1 , the additional acceleration corresponding to the steering speed gradually approaches the predetermined upper limit value _Amax as the steering speed increases. That is, as the steering speed increases, the additional acceleration increases, and the rate of increase in the amount of increase decreases. This upper limit value A _max is set to an acceleration that does not make the driver feel that there has been control intervention even if acceleration is added to the vehicle 100 in response to steering operation (for example, 0.5 m/s ² ≈0.05 G). ). Furthermore, when the steering speed is equal to or greater than the threshold _S2 , which is greater than the threshold _S1 , the additional acceleration is maintained at the upper limit value _Amax .

Next, in step S34, the controller 60 sets the increased torque based on the additional acceleration set in step S33. Specifically, the controller 60 determines the increased torque to be applied to the vehicle 100 in order to realize the additional acceleration based on the current vehicle speed, gear stage, road gradient, etc. acquired in step S11 of FIG. After step S34, the controller 60 ends the increased torque setting process and returns to the main routine of FIG.

On the other hand, if it is determined that the steering angle has not increased in step S31 (step S31: No), or if it is determined that the steering speed is less than the threshold value _S1 in step S32 (step S32: No). , the controller 60 ends the increased torque setting process without setting the increased torque, and returns to the main routine of FIG. In this case, the increased torque is 0.

Returning to FIG. 6, after the increased torque setting process (step S14), the controller 60 proceeds to step S15 and executes the increased torque application process shown in FIG.

As shown in FIG. 10, when the increased torque application process is started, in step S41, the controller 60 determines whether or not the combustion mode of the engine 1 is set to the second combustion mode. For example, the controller 60 determines the current combustion mode of the engine 1 based on the operation map shown in FIG. 4 and the current operating state of the engine 1 (engine load and engine speed).

As a result of step S41, when it is determined that the second combustion mode is set (step S41: Yes), the controller 60 proceeds to step S42, and sets the increased torque set in the increased torque setting process to the motor generator. 114, an assist amount (that is, driving torque) of the motor generator 114 corresponding to the increased torque is set. By doing so, in the second combustion mode of the SPCCI combustion, the drive torque from the motor generator 114 is applied to the vehicle 100, thereby generating additional acceleration to the vehicle 100 and controlling the vehicle attitude. After step S42, the controller 60 ends the increased torque application process and returns to the main routine of FIG.

On the other hand, if it is determined that the second combustion mode is not set (step S41: No), that is, if the first combustion mode is set or SI combustion is being performed, the controller 60 , in step S43, in order to realize the increased torque set in the increased torque setting process by increasing the torque of the engine 1, specifically by advancing the ignition timing of the spark plug 16, the increased torque Set the ignition timing advance amount corresponding to . By doing this, in the first combustion mode of the SPCCI combustion and in the SI combustion, by increasing the torque of the engine 1 applied to the vehicle 100, additional acceleration is generated in the vehicle 100 to control the vehicle posture. . After step S43, the controller 60 ends the increased torque application process and returns to the main routine of FIG.

Note that if the increased torque is not set in the increased torque setting process (that is, if the increased torque is 0), the above steps S42 and S43 are not performed. In other words, setting of the assist amount of the motor generator 114 and setting of the ignition timing advance amount are not performed. In this case, vehicle attitude control is not performed.

Returning to FIG. 6, the controller 60 proceeds to step S16 after the increased torque application process (step S15). In step S16, the controller 60 sets the control command value for the engine 1, the control command value for the motor generator 114, the assist amount and the ignition timing advance amount for the motor generator 114, and the values set by the motor generator setting process. Based on the contents, the control amount of each actuator that drives each component of the engine 1 and the motor generator 114 is set. In this case, the controller 60 sets a limit value and a limit range according to the state quantity, and sets a control amount for each actuator such that the state value complies with the limit set by the limit value and the limit range. Next, the controller 60 proceeds to step S17, and outputs control commands to the actuators of the engine 1 and the motor generator 114 based on the control amounts set in step S16. After that, the controller 60 terminates the overall control shown in FIG.

<Action and effect>
Next, actions and effects of the vehicle system according to the embodiment of the present invention will be described.

FIG. 11 is an example of a time chart showing temporal changes of various parameters when vehicle attitude control is executed according to the embodiment of the present invention. The time chart of FIG. 11 shows, from top to bottom, the steering angle of the steering wheel 105, the steering speed of the steering wheel 105, the additional acceleration set in the increased torque setting process (step S33 in FIG. 8), the second SPCCI combustion, Mode ON/OFF, ignition timing of the ignition plug 16 of the engine 1, torque (driving torque or regenerative torque) of the motor generator 114, and actual yaw rate are shown.

First, when the steering wheel 105 is turned, that is, when the vehicle 100 turns in, the steering angle and the steering speed increase. As a result, at time t11, the steering speed becomes equal to or _greater than the threshold S1 (step S32 in FIG. 8: Yes), and additional acceleration corresponding to the steering speed is set (step S33 in FIG. 8). Also, an increased torque is set according to this additional acceleration (step S34 in FIG. 8). In the example shown in FIG. 11, since the second combustion mode of SPCCI combustion is on, the drive torque (assist amount) of motor generator 114 corresponding to the increased torque is set so that motor generator 114 executes torque assist. (Step S41 in FIG. 10: Yes→Step S42), vehicle attitude control is executed. In this case, control for advancing the ignition timing is not performed, that is, the ignition timing is maintained constant. By applying the driving torque (positive torque) set in this manner to the vehicle 100, additional acceleration is generated in the vehicle 100, the front portion of the vehicle body sinks, and the front wheel load increases (see FIG. 5). As a result, a desired actual yaw rate is generated in the vehicle 100 when the steering wheel 105 is turned, so that the responsiveness and linearity of the vehicle 100 to the steering wheel 105 can be improved. After that, when the steering speed decreases during the vehicle attitude control, the steering speed becomes less than the threshold _S1 at time t12 (step S32 in FIG. 8: No), and the vehicle attitude control ends.

FIG. 12 is another example of a time chart showing changes over time of various parameters when vehicle attitude control is executed according to the embodiment of the present invention. The time chart of FIG. 12 also shows the steering angle, steering speed, additional acceleration, ON/OFF of the second combustion mode, ignition timing, torque of the motor generator 114, and actual yaw rate in order from the top.

First, when the steering wheel 105 is turned, that is, when the vehicle 100 turns in, the steering angle and the steering speed increase. As a result, at time t21, the steering speed becomes equal to or _greater than the threshold S1 (step S32 in FIG. 8: Yes), and additional acceleration corresponding to the steering speed is set (step S33 in FIG. 8). Also, an increased torque is set according to this additional acceleration (step S34 in FIG. 8). In the example shown in FIG. 12, since the second combustion mode of SPCCI combustion is off, that is, the first combustion mode or SI combustion is being performed, ignition corresponding to the increased torque is performed to increase the torque of the engine 1. A timing advance amount is set (step S41 in FIG. 10: No→step S43), and vehicle attitude control is executed. In this case, torque assist for the motor generator 114 is not performed. The ignition timing advance amount is set based on a predetermined reference ignition timing (ignition timing applied during normal operation, that is, when vehicle attitude control is not performed). This reference ignition timing is typically an ignition timing that is slightly retarded from the so-called minimum advance for the best torque (MBT). By advancing the reference ignition timing, the torque of the engine 1 can be increased appropriately.

By applying the ignition timing advance amount set in this way to increase the torque of the engine 1 applied to the vehicle 100, additional acceleration is generated in the vehicle 100, causing the front portion of the vehicle body to sink and the front wheel load to increase. increases (see FIG. 5). With this, a desired actual yaw rate is generated in the vehicle 100 when the steering wheel 105 is turned, so that the responsiveness and linearity of the vehicle 100 to the steering wheel 105 can be improved. After that, when the steering speed decreases during the vehicle attitude control, the steering speed becomes less than the threshold value _S1 at time t22 (step S32 in FIG. 8: No), and the vehicle attitude control ends.

As described above, according to the present embodiment, when the SPCCI combustion (first combustion mode) in which the air-fuel ratio is set to the stoichiometric air-fuel ratio or the richer side than the stoichiometric air-fuel ratio is performed, the controller 60 controls the additional acceleration is generated in the vehicle 100, while the SPCCI combustion (second combustion mode) in which the air-fuel ratio is set leaner than the stoichiometric air-fuel ratio is performed, the additional acceleration is Control is performed so that torque for driving the rear wheels 103 is generated from the motor generator 114 so as to be generated in the vehicle 100 . That is, in the second combustion mode, the controller 60 does not advance the ignition timing (maintains the ignition timing constant), but performs torque assist by the motor generator 114 so as to generate additional acceleration in the vehicle 100. do. As a result, during execution of SPCCI combustion in which the air-fuel ratio of the air-fuel mixture is set to the lean side, it is possible to appropriately execute vehicle attitude control while ensuring combustion stability.

Further, according to the present embodiment, the controller 60 prohibits regenerative power generation by the motor generator 114 in the second combustion mode. As a result, when vehicle attitude control is performed during the second combustion mode, it is possible to suppress delays in the torque assist of motor generator 114 for this control. Specifically, by prohibiting regenerative power generation, the belt 112 connected to the motor generator 114 is always stretched (stretched) in the direction of the torque assist side, so that the vehicle posture control can be performed during the second combustion mode. When there is a request, the motor generator 114 can be quickly torque-assisted, and the desired vehicle attitude control can be appropriately achieved.

<Modification>
In the above-described embodiment, the rubber belt 112 was shown as an example of the "wrapping member" in the present invention, but in other examples, instead of such a belt 112, a belt made of a material other than rubber Alternatively, a chain different from the belt may be used as the wrapping member.

Further, in the above-described embodiment, the ignition timing of the spark plug 16 is controlled in order to generate additional acceleration in the vehicle 100. may be controlled. In this case, the throttle valve 32 is controlled to open to reduce the pumping loss, thereby causing the vehicle 100 to generate additional acceleration.

Further, in the above-described embodiment, regenerative power generation of motor generator 114 is prohibited in the second combustion mode. Regenerative power generation may be suppressed, that is, regenerative power generation may be permitted to some extent. For example, in a specific situation where motor generator 114 should be regeneratively generated, typically when vehicle 100 is decelerating to stop, motor generator 114 is regeneratively generated even in the second combustion mode. good too.

Further, in the above-described embodiment, the vehicle attitude control is executed based on the steering angle and steering speed, but in other examples, instead of the steering angle and steering speed, the yaw rate, lateral acceleration, yaw acceleration, and lateral jerk are used. Vehicle attitude control may be executed based on the

1 engine 1a engine body 15 injector 16 spark plug 32 throttle valve 60 controller 100 vehicle 101 vehicle body 102 front wheel 103 rear wheel 104 steering device 105 steering wheel 112 belt 114 motor generator SN1 crank angle sensor SN10 accelerator opening sensor SN11 steering angle sensor

Claims (7)

A rear wheel drive vehicle system comprising:
an engine having at least spark plugs and communicating with the rear wheels;
a rotating electrical machine in communication with the rear wheels;
an operating state sensor that detects the operating state of the engine;
a steering wheel operated by a driver;
a steering angle sensor that detects a steering angle corresponding to the operation of the steering wheel;
a controller for controlling the engine and the rotating electrical machine;
The engine has a combustion mode in which a part of the air-fuel mixture in the cylinder of the engine is burned by spark ignition by the spark plug, and then the remaining air-fuel mixture in the cylinder is burned by self-ignition,
The controller is
setting additional acceleration to be applied to the vehicle based on the steering angle detected by the steering angle sensor when the steering wheel is turned;
When the engine performs the combustion mode, the air-fuel ratio of the air-fuel mixture is adjusted to a first air-fuel ratio and a second air-fuel ratio leaner than the first air-fuel ratio, based on the operating state of the engine detected by the operating state sensor. 2 set to either one of the air-fuel ratios,
When the first air-fuel ratio is set, the ignition timing of the spark plug is controlled so as to generate the additional acceleration in the vehicle, and when the second air-fuel ratio is set, the additional acceleration is controlled. control to generate torque for driving the rear wheels from the rotating electric machine so that the vehicle generates
A vehicle system characterized by: The rotating electric machine is connected to the rear wheel via a winding member,
The controller is configured to suppress regenerative power generation of the rotating electrical machine when the second air-fuel ratio is set.
A vehicle system according to claim 1 . 3. The vehicle system of claim 2, wherein said wrapping member is a belt. The vehicle system according to any one of claims 1 to 3, wherein the first air-fuel ratio is a stoichiometric air-fuel ratio or an air-fuel ratio richer than the stoichiometric air-fuel ratio. The vehicle system according to any one of claims 1 to 4, wherein the second air-fuel ratio is an air-fuel ratio leaner than the stoichiometric air-fuel ratio. 6. The vehicle system according to claim 5, wherein said second air-fuel ratio is defined by a ratio of air amount to fuel amount in said air-fuel mixture, and this ratio is set within a range of 25-30. 7. The controller according to any one of claims 1 to 6, wherein the controller determines a steering speed from the steering angle detected by the steering angle sensor, and sets the additional acceleration based on the steering speed. the vehicle system described in .

Images