JP2023173701A - Engine system and series hybrid vehicle - Google Patents

Abstract

To form a homogeneous air-fuel mixture in a working chamber even when the engine rotation speed is low.SOLUTION: An engine system 12 comprises: a rotary engine 14 having a rotor housing 16, side housings 18, a rotor 20 that is housed in a rotor accommodation chamber surrounded by the rotor housing and the side housings and forms three working chambers 24, and an injector 54 for injecting fuel into one of the working chambers; an eccentric shaft angle sensor 58 for detecting an engine rotation speed of the rotary engine; and an ECM 70 configured to control fuel injection by the injector. When the engine rotation speed is equal to or lower than a first rotation speed, the ECM controls the injector such that the number of times of fuel injection in one combustion cycle of each of the working chambers is greater and the end timing of a last fuel injection is retarder than those when the engine rotation speed is higher than the first rotation speed.SELECTED DRAWING: Figure 10

Description

The present invention relates to an engine system and a series hybrid vehicle, and more particularly to an engine system and a series hybrid vehicle equipped with a rotary engine.

Conventionally, rotary engines are known that include a rotor housing, a side housing, and a rotor housed in a rotor housing chamber surrounded by these housings. For example, Patent Document 1 discloses that in a rotary engine, in order to secure fuel vaporization time and promote mixing of fuel and fresh air, a fuel injection valve is installed on the lagging side of the rotor in the intake working chamber in the first half of the intake stroke. It is disclosed that the jetting direction of the jet is set.

Japanese Patent Application Publication No. 2017-053332

By the way, in a rotary engine, fuel injected into a working chamber flows through the working chamber while mixing with fresh air flowing in from an intake port to form an air-fuel mixture. However, when the engine speed is relatively low, that is, when the rotor rotational speed is low, the trailing side of the working chamber that occurs due to rotor rotation (lag side, that is, the rear side in the rotor rotational direction) Since the airflow such as squish flow from the leading side (advance side, that is, the forward side in the rotor rotational direction) is weakened, it is not possible to flow the fuel sufficiently so that it is blown back from the leading side to the trailing side. As a result, the fuel is not evenly distributed throughout the working chamber and remains on the leading side. That is, the distribution of fuel in the working chamber becomes uneven, and air becomes insufficient in a region where fuel is rich, resulting in an increase in unburned fuel, leading to deterioration of fuel efficiency and emissions.

The present invention has been made to solve these problems, and provides an engine system equipped with a rotary engine and a series hybrid that can form a homogeneous air-fuel mixture in the working chamber even when the engine speed is low. The purpose is to provide vehicles.

To achieve the above object, an engine system according to the present invention includes a rotor housing, a side housing, and a rotor housed in a rotor accommodation chamber surrounded by the rotor housing and the side housing, forming three working chambers. and an injector that injects fuel into one of the working chambers, a rotation speed sensor that detects the engine rotation speed of the rotary engine, and a controller configured to control fuel injection by the injector. , the controller controls the number of times of fuel injection in one combustion cycle of each of the working chambers when the engine speed is less than or equal to the first speed than when the engine speed is higher than the first speed. The injector is controlled so that the most and final fuel injection end timing is retarded.
According to the present invention configured in this way, when the engine speed is relatively low, that is, when the airflow in the working chamber is relatively weak, the number of fuel injections in one combustion cycle of each working chamber is increased. At the same time, by retarding the end timing of the last fuel injection, even if the airflow in the working chamber is weak, the fuel can be distributed evenly from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

Preferably, in the present invention, the controller controls each of the working chambers when the engine speed is a second rotation speed or less lower than the first rotation speed than when the engine speed is higher than the second rotation speed. The injector is controlled so that the number of fuel injections in one combustion cycle is large and the injection end timing of the last fuel injection is delayed.
According to the present invention configured in this way, the lower the engine speed is, that is, the weaker the airflow in the working chamber, the greater the number of fuel injections in one combustion cycle of each working chamber, and the more fuel is injected in one combustion cycle of each working chamber. By retarding the end timing of the last fuel injection, even when the airflow in the working chamber is weaker, the fuel can be evenly distributed from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

Preferably, in the present invention, when the engine speed is equal to or lower than the first rotation speed, the controller is configured such that the higher the load of the rotary engine at the same engine speed, the higher the load of the rotary engine in one combustion cycle of each of the working chambers. The injector is controlled so that the ratio of the first fuel injection amount is increased.
According to the present invention configured in this manner, when the engine speed is the same, the higher the engine load, the greater the amount of fresh air flowing into the working chamber, and the stronger the airflow toward the leading side. The higher the fuel injection rate, the larger the ratio of the first fuel injection amount and the more fuel injected to the leading side, which promotes the mixing of fresh air flowing to the leading side and fuel to obtain a homogeneous air-fuel mixture. I can do it.

In another aspect, the present invention provides a series hybrid vehicle comprising an electric motor as a driving force source and a generator capable of supplying electric power to the electric motor, comprising the above-mentioned engine system, and a rotary engine. , to drive the generator.
In series hybrid vehicles that use the driving force of the rotary engine only to drive the generator, the rotary engine tends to be operated in a region of high thermal efficiency, that is, a region where the engine speed is relatively low and the airflow in the operating chamber is weak. be. Therefore, the engine system according to the present invention, which can obtain a homogeneous air-fuel mixture even in a region where the engine speed is relatively low and the airflow in the working chamber is weak, is suitable for series hybrid vehicles.

According to the engine system and series hybrid vehicle of the present invention, a homogeneous air-fuel mixture can be formed in the working chamber even when the engine speed is low.

1 is a configuration diagram of a series hybrid vehicle according to an embodiment of the present invention. 1 is a configuration diagram of an engine system according to an embodiment of the present invention. 1 is a control block diagram of a series hybrid vehicle according to an embodiment of the present invention. FIG. 5 is a flowchart of engine control processing according to an embodiment of the present invention. 5 is a flowchart of engine start control processing according to an embodiment of the present invention. It is a map showing the relationship between water temperature and required rotation speed in engine start control according to the embodiment of the present invention. It is a map showing the relationship between water temperature and rotational increase rate in engine start control according to the embodiment of the present invention. It is a map which shows the relationship between the water temperature and the oil introduction amount at the time of starting in engine starting control according to an embodiment of the present invention. 5 is a flowchart of combustion control processing according to an embodiment of the present invention. 5 is a chart illustrating a pattern of fuel injection timing according to engine speed in combustion control according to an embodiment of the present invention. It is a table showing the relationship between the engine rotation speed and the number of fuel injections in combustion control according to the embodiment of the present invention. It is a map showing the relationship between engine speed and fuel injection end timing in combustion control according to an embodiment of the present invention. 5 is a map showing the relationship between engine load and fuel injection amount division ratio in combustion control according to an embodiment of the present invention. It is a graph showing the relationship between eccentric shaft angle and heat generation rate in a rotary engine. It is a graph showing the relationship between the EGR rate and the second stage combustion rate in a rotary engine. It is a map showing the relationship between engine load and EGR rate in combustion control according to an embodiment of the present invention. It is a map showing the relationship between engine speed and EGR rate in combustion control according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<System configuration>
First, the configuration of a series hybrid vehicle and engine system according to this embodiment will be explained with reference to FIGS. 1 and 2. FIG. 1 is a block diagram of a series hybrid vehicle, and FIG. 2 is a block diagram of an engine system.

As shown in FIG. 1, the series hybrid vehicle 1 is capable of supplying electric power to the electric motor 6, which is a driving force source that drives the drive wheels 4 (in the example shown, the front wheels) via the reduction gear 2. It is equipped with a battery 8 and a starter generator 10. Further, the series hybrid vehicle 1 includes an engine system 12 having a rotary engine 14. The starter generator 10 is driven by the rotary engine 14 to generate electricity and supply power to the electric motor 6 and the battery 8, and when the rotary engine 14 is started, the rotary engine 14 is driven by the power supplied from the battery 8.

As shown in FIG. 2, the engine system 12 includes a rotary engine 14. The rotary engine 14 includes a rotor housing 16 having a trochoidal inner circumferential surface, side housings 18 having planar inner surfaces disposed on both sides of the rotor housing 16, and surrounded by the rotor housing 16 and the side housing 18. The rotor 20 is housed in a rotor housing chamber.

The rotor 20 is supported by an inner eccentric shaft 22 and rotates eccentrically together with the eccentric shaft 22. Three working chambers 24 are formed around the rotor 20 and are surrounded by the rotor housing 16, the side housing 18, and the rotor 20. The volume of each working chamber 24 is changed by eccentric rotation of the rotor 20. A series of intake, compression, expansion (explosion), and exhaust strokes in the working chamber 24 cause the rotor 20 to rotate and the eccentric shaft 22 to rotate, and the rotational force is used as motive power from the eccentric shaft 22 to the drive shaft ( (not shown), etc., to the starter generator 10.

As shown in FIG. 2, a spark plug 26 is attached to the rotor housing 16, and an intake port 28 and an exhaust port 30 are formed in the side housing 18. An intake passage 32 is connected to the intake port 28, and air is introduced into the working chamber 24 through the intake passage 32. Further, an exhaust passage 34 is connected to the exhaust port 30, and exhaust gas in the working chamber 24 is exhausted through the exhaust passage 34. The rotor 20 rotates clockwise in FIG. 2, and in the state shown in FIG. 2, the compression stroke is performed in the upper right working chamber 24 of the rotor 20, and the expansion (explosion) stroke is performed in the lower right working chamber 24. It is being said. In the example of FIG. 2, the rotor 20 rotates clockwise, so the leading side of the working chamber 24 is the clockwise side of the working chamber 24 (that is, the lower right side of the working chamber 24 at the upper right of the rotor 20, In the lower right working chamber 24, the lower left side), and the trailing side (lag side) is the counterclockwise side of the working chamber 24 (in other words, in the upper right working chamber 24 of the rotor 20, the upper left side and the lower right working chamber 24, it is on the upper right side).

As shown in FIG. 2, a throttle valve 36, a throttle opening sensor 38, and an air flow sensor 40 are provided on the upstream side of the intake passage 32, and an air cleaner 42 is further provided on the upstream side thereof. Further, on the downstream side of the exhaust passage 34, an EGR device 44 and an exhaust gas purification catalyst (not shown) for recirculating part of the exhaust gas in the exhaust passage 34 to the intake passage 32 are provided. The EGR device 44 includes an EGR passage 46 that connects the exhaust passage 34 and the intake passage 32, an EGR cooler 48 that cools and increases the density of exhaust gas recirculating in the EGR passage 46, and an EGR rate (operated during the intake stroke). It has an EGR valve 50 and an EGR valve opening sensor 52 for controlling the ratio of the amount of burned gas to the total amount of gas flowing into the chamber 24.

Further, an injector 54 that injects fuel into the working chamber 24 and a metering oil pump 56 that injects oil onto the inner peripheral surface of the rotor housing 16 are attached to the rotor housing 16. The injector 54 is connected to a fuel tank via a fuel supply passage (none of which is shown), and is supplied with fuel from the fuel tank. The metering oil pump 56 is, for example, an electromagnetically operated oil pump, which measures oil taken out from an oil gallery (not shown) and pumps the required amount of oil into the rotor housing 16 from an oil nozzle (not shown). It is designed to be sprayed onto the surrounding surface.

Furthermore, an eccentric shaft angle sensor 58 that detects the rotation angle of the eccentric shaft 22 is attached to the rotary engine 14. The rotational speed of the eccentric shaft 22, that is, the engine rotational speed of the rotary engine 14 can be detected from the rotation angle detected by the eccentric shaft angle sensor 58. Therefore, the eccentric shaft angle sensor 58 corresponds to the "rotation speed sensor" in the present invention. Further, the intake passage 32 is provided with an intake pressure sensor 60 that detects the intake air pressure in the intake passage 32, and an intake air temperature sensor 62 that detects the intake air temperature. Further, although not shown in FIG. 2, the rotary engine 14 is also provided with a water temperature sensor 64 that detects the temperature (water temperature) of the engine cooling water.

The engine system 12 includes an ECM (Electronic Control Module) 70 that serves as an arithmetic unit and a control unit that controls the rotary engine 14 . ECM 70 is a well-known microcomputer-based controller. The ECM 70 is configured by a computer including one or more processors (typically a CPU) 72, a storage section (ROM, RAM, etc.) 74 that stores various programs, and the like. Note that the ECM 70 corresponds to an example of a "controller" in the present invention.

The ECM 70 controls the spark plugs 26, injectors 54, and metals of the rotary engine 14 based on signals input from the various sensors 38, 40, 52, 58, 60, 62, and 64 described above and a PCM (Powertrain Control Module) 84, which will be described later. The control amount of each device such as the ring oil pump 56, the throttle valve 36, and the EGR valve 50 is calculated, and an electric signal corresponding to the calculated control amount is output to those devices. The PCM 84 is a controller that controls the entire power system of the series hybrid vehicle 1 including the electric motor 6, starter generator 10, engine system 12, reduction gear 2, battery 8, etc., and includes one or more processors (typically The computer includes a CPU (CPU), a storage unit (ROM, RAM, etc.) that stores various programs, and the like. Note that the PCM 84 corresponds to an example of a "controller" in the present invention.

<Overview of engine control>
Next, with reference to FIG. 3, an outline of engine control in the series hybrid vehicle 1 according to this embodiment will be explained. FIG. 3 is a control block diagram of the series hybrid vehicle according to this embodiment.

The battery 8 of the series hybrid vehicle 1 is provided with a voltage sensor 76 that detects the output voltage of the battery 8 and a current sensor 78 that detects the output current of the battery 8. These voltage sensor 76 and current sensor 78 output electric signals corresponding to respective detected values to a BCM (Battery Control Module) 80. The BCM 80 is a controller that mainly controls the charging and discharging of the battery 8, and is composed of a computer equipped with one or more processors (typically a CPU), a storage unit (ROM, RAM, etc.) that stores various programs, etc. be done.

The BCM 80 estimates the SOC (State of Charge) of the battery 8 from the voltage value and current value of the battery 8 input from the voltage sensor 76 and the current sensor 78, and outputs it to the PCM 84. The PCM 84 generates a desired engine output based on the SOC input from the BCM 80 and the accelerator opening input from the accelerator opening sensor 82 that detects the opening of the accelerator pedal (not shown) of the series hybrid vehicle 1. The rotational speed (required engine rotational speed) and load (required engine load) of the rotary engine 14 necessary to obtain the same are calculated and output to the ECM 70.

In addition, when starting the rotary engine 14, the PCM 84 determines the number of revolutions (required number of revolutions) at which the eccentric shaft 22 of the rotary engine 14 is rotated by the starter generator 10, based on the water temperature of the rotary engine 14 inputted from the ECM 70. The rate of increase in rotational speed (rotation increase rate) is calculated and output to a SGCM (Starter Generator Control Module) 86. The SGCM 86 is a controller that mainly controls the starter generator 10, and is composed of a computer that includes one or more processors (typically a CPU), a storage unit that stores various programs (ROM, RAM, etc.), and the like. Ru. Note that the SGCM 86 corresponds to an example of a "controller" in the present invention.

The ECM 70 controls the control amount of each device such as the metering oil pump 56, injector 54, spark plug 26, EGR valve 50, throttle valve 36, etc. of the rotary engine 14 based on the required engine speed and required engine load input from the PCM 84. is calculated, and an electrical signal corresponding to the calculated control amount is output to those devices. Furthermore, when starting the rotary engine 14, the SGCM 86 calculates a control amount for the starter generator 10 based on the required rotation speed and rotation increase rate input from the PCM 84, and sends an electric signal corresponding to the calculated control amount to the starter generator 10. Output to.

<Engine control processing>
Next, with reference to FIG. 4, the flow of engine control processing according to this embodiment will be described. FIG. 4 is a flowchart of engine control processing according to this embodiment.

The engine control process shown in FIG. 4 is repeatedly executed at predetermined intervals by the PCM 84, ECM 70, and SGCM 86 when the rotary engine 14 is stopped.

First, in step S101, the PCM 84 acquires various information regarding the state of the series hybrid vehicle 1 from the ECM 70, BCM 80, accelerator opening sensor 82, and the like. Specifically, for example, the PCM 84 receives the SOC input from the BCM 80, the accelerator opening input from the accelerator opening sensor 82, the water temperature of the rotary engine 14 input from the ECM 70, as well as vehicle speed, motor rotation speed, etc. get. Thereafter, the PCM 84 continuously acquires this information while the engine control process is being executed.

Next, in step S102, the PCM 84 calculates the torque to be output by the electric motor 6 (required motor torque) based on the information acquired in step S101. Specifically, the PCM 84 refers to a map or calculation formula (preset and stored) that defines the relationship between the accelerator opening degree and the required motor torque, and generates a request corresponding to the accelerator opening degree acquired in step S101. Calculate motor torque.

Next, in step S103, the PCM 84 determines whether the SOC acquired in step S101 is less than or equal to a predetermined threshold value (for example, an allowable lower limit of SOC, which is set and stored in advance). As a result, if the SOC is not below the threshold value (step S103: No), that is, if the SOC is greater than the threshold value and there is no need to start the rotary engine 14 in order to charge the battery 8 with the starter generator 10, the process proceeds to step S104. move on.

In step S104, the PCM 84 determines whether the required motor torque calculated in step S102 is larger than the torque that the electric motor 6 can output (outputable motor torque). The outputtable motor torque is, for example, the torque that the electric motor 6 can output using only the electric power supplied from the battery 8, and a map or calculation formula that defines the relationship between the SOC, the motor rotation speed, and the outputtable motor torque is set in advance. and is remembered. The PCM 84 refers to these maps and calculation formulas, obtains the outputtable motor torque corresponding to the SOC, motor rotation speed, etc. obtained in step S101, and compares it with the required motor torque.

As a result of the determination in step S104, if the requested motor torque is not larger than the outputtable motor torque (step S104: No), that is, the required motor torque is less than or equal to the outputtable motor torque, and the starter generator 10 supplies electric power to the electric motor 6. If there is no need to start the rotary engine 14 in order to do so, the PCM 84 ends the engine control process without starting the rotary engine 14.

On the other hand, as a result of the determination in step S103, if the SOC is less than or equal to the threshold value (step S103: Yes), that is, if it is necessary to start the rotary engine 14 in order to charge the battery 8 with the starter generator 10, or As a result of the determination in S104, if the required motor torque is larger than the outputtable motor torque (Step S104: Yes), that is, if it is necessary to start the rotary engine 14 in order to supply electric power from the starter generator 10 to the electric motor 6, Proceeding to step S105, the PCM 84, ECM 70, and SGCM 86 execute engine start control to start the rotary engine 14. Details of this engine start control will be described later.

After the rotary engine 14 is started by the engine start control in step S105, in step S106, the PCM 84 and ECM 70 execute combustion control to operate the rotary engine 14 at a required output. Details of this combustion control will be described later.

Next, in step S107, the PCM 84 determines whether the SOC acquired from the BCM 80 immediately before is equal to or greater than a target value (for example, an allowable upper limit value of the SOC, which is set and stored in advance). As a result, if the SOC is not greater than or equal to the target value (step S107: No), that is, if the SOC is smaller than the target value and it is necessary to continue charging the battery 8 by the starter generator 10, the process returns to step S106 and the rotary engine 14 combustion control will continue.

On the other hand, as a result of the determination in step S107, if the SOC is equal to or greater than the target value (step S107: Yes), that is, if it is not necessary to charge the battery 8 by the starter generator 10, the process proceeds to step S108.

In step S108, the PCM 84 determines whether the required motor torque is less than or equal to the outputtable motor torque. As a result, if the required motor torque is not less than the outputtable motor torque (step S108: No), that is, the required motor torque is greater than the outputtable motor torque, and it is necessary to continue supplying power from the starter generator 10 to the electric motor 6. If there is, the process returns to step S106 and combustion control of the rotary engine 14 is continued.

On the other hand, as a result of the determination in step S108, if the required motor torque is less than or equal to the outputtable motor torque (step S108: Yes), that is, if there is no need to supply power from the starter generator 10 to the electric motor 6, the process advances to step S109; The PCM 84 stops the rotary engine 14 and ends the engine control process.

<Engine start control processing>
Next, the flow of engine start control according to this embodiment will be described with reference to FIGS. 5 to 8. FIG. 5 is a flowchart of the engine start control process according to the present embodiment, FIG. 6 is a map showing the relationship between water temperature and required rotation speed in engine start control, and FIG. 7 is a map showing the relationship between water temperature and rotation increase rate in engine start control. The map shown in FIG. 8 is a map showing the relationship between the water temperature and the amount of oil introduced at startup in engine startup control.

As shown in FIG. 5, when the engine starting control is started, first in step S201, the PCM 84 controls the eccentricity of the rotary engine 14 by the starter generator 10 based on the water temperature of the rotary engine 14 acquired in step S101 of the engine control process. The required rotation speed (required rotation speed) when rotating the shaft 22 and starting ignition by the spark plug 26 is set and output to the SGCM 86. Specifically, the PCM 84 refers to a map (preset and stored in advance) that defines the relationship between water temperature and required rotation speed, as shown in FIG. Set the required rotation speed. In the map illustrated in FIG. 6, the horizontal axis represents the water temperature, and the vertical axis represents the required rotation speed. According to the map in FIG. 6, when the water temperature is less than Tr (℃), the required rotation speed is set to Rr1 (rpm), and when the water temperature is Tr (℃) or higher, the required rotation speed is higher than Rr1. It is set to Rr2 (rpm). The water temperature Tr and the required rotational speeds Rr1 and Rr2 can be set to, for example, Tr=−5° C., Rr1=1200 rpm, and Rr2=2000 rpm, but other appropriate values can be set depending on the rotary engine 14.

In this way, when the water temperature is relatively low when starting the engine, that is, during a cold start when the clearance between the rotor housing 16 and the rotor 20 is large and it is difficult for oil to intervene, compared to when the water temperature is relatively high. By setting the required rotation speed low, the airflow in the working chamber 24 is weakened until the rotary engine 14 starts ignition, thereby preventing the introduced oil from being blown away by the airflow before the rotary engine 14 starts ignition. can do.

Next, in step S202, the PCM 84 determines the rate of increase in the rotational speed (rotation increase) when the eccentric shaft 22 of the rotary engine 14 is rotated by the starter generator 10, based on the water temperature of the rotary engine 14 acquired in step S101 of the engine control process. rate) and output it to the SGCM86. Specifically, the PCM 84 refers to a map (preset and stored in advance) that defines the relationship between water temperature and rotational increase rate, as shown in FIG. Set the rotation increase rate. In the map illustrated in FIG. 7, the horizontal axis represents the water temperature, and the vertical axis represents the rotational increase rate. According to the map in FIG. 7, when the water temperature is less than Ti1 (°C), the rotation increase rate is set to Ir1 (rpm/s), and when the water temperature is greater than or equal to Ti1 (°C) and less than Ti2 (°C), the rotation increase rate is set to Ir1 (rpm/s). If the rotational increase rate is set to Ir2 (rpm/s) and the water temperature is greater than or equal to Ti2 (°C) and less than Ti3 (°C), the rotational increase rate is set to Ir3 (rpm/s) and the water temperature is Ti3 (°C). If the water temperature is less than Ti4 (°C), the rotational increase rate is set to Ir4 (rpm/s), and if the water temperature is equal to or higher than Ti4 (°C), the rotational increase rate is set to Ir5 (rpm/s). Here, the magnitude relationship of the rotational increase rate is Ir1<Ir2<Ir3<Ir4<Ir5. The water temperature and rotation rate of increase are, for example, water temperature Ti1=-5℃, Ti2=5℃, Ti3=15℃, Ti4=25℃, and rotation rate of increase Ir1=1500rpm/s, Ir2=2100rpm/s, Ir3= 2600 rpm/s, Ir4=3200 rpm/s, Ir5=3600 rpm/s, but other suitable values can be set depending on the rotary engine 14.

In this way, when the water temperature is relatively low when starting the engine, that is, during a cold start when the clearance between the rotor housing 16 and the rotor 20 is large and it is difficult for oil to intervene, compared to when the water temperature is relatively high. By setting the rotation increase rate low, the rate of increase in the strength of the airflow in the working chamber 24 becomes gradual, so that the oil introduced into the rotor housing 16 is sufficiently distributed between the rotor housing 16 and the rotor 20. This can prevent it from being blown away by the airflow before it can spread.

Next, in step S203, the ECM 70 determines the amount of oil to be introduced into the rotor housing 16 by the metering oil pump 56 when starting the rotary engine 14 (at the time of starting), based on the water temperature of the rotary engine 14 acquired in step S101 of the engine control process. (oil introduction amount). Specifically, the ECM 70 refers to a map (preset and stored in advance) that defines the relationship between the water temperature and the amount of oil introduced at startup, as shown in FIG. Set the corresponding starting oil introduction amount. In the map illustrated in FIG. 8, the horizontal axis represents the water temperature, and the vertical axis represents the amount of oil introduced at startup. According to the map in FIG. 8, the higher the water temperature, the smaller the amount of oil introduced at startup (l/min).

In this way, when the water temperature is relatively low when starting the engine, that is, during a cold start when the clearance between the rotor housing 16 and the rotor 20 is large and it is difficult for oil to intervene, compared to when the water temperature is relatively high. By setting a large amount of oil to be introduced at startup, oil can be reliably spread between the rotor housing 16 and the rotor 20.

Next, in step S204, the ECM 70 and SGCM 86 start the rotary engine 14. Specifically, the SGCM 86 drives the starter generator 10 and rotates the eccentric shaft 22 of the rotary engine 14 according to the required rotation speed and rotation increase rate input from the PCM 84 in steps S201 and S202. In addition, the ECM 70 causes the metering oil pump 56 to introduce oil into the rotor housing 16 in the starting oil introduction amount set in step S203, and when the rotational speed of the eccentric shaft 22 reaches the required rotational speed, the injector 54 Fuel injection and ignition by the spark plug 26 are started. After starting the rotary engine 14 in step S204, the PCM 84 ends the engine starting control and returns to the engine control shown in FIG. 4.

<Combustion control processing>
Next, the flow of combustion control of the rotary engine according to this embodiment will be described with reference to FIGS. 9 to 17. FIG. 9 is a flowchart of the combustion control process according to the present embodiment, FIG. 10 is a chart illustrating a pattern of fuel injection timing according to the engine speed in combustion control, and FIG. 11 is a chart showing the relationship between the engine speed and the number of fuel injections in combustion control. A table showing the relationship, FIG. 12 is a map showing the relationship between engine speed and fuel injection end timing in combustion control, FIG. 13 is a map showing the relationship between engine load and fuel injection amount division ratio in combustion control, and FIG. is a graph showing the relationship between eccentric shaft angle and heat release rate in a rotary engine, FIG. 15 is a graph showing a relationship between EGR rate and second stage combustion rate in a rotary engine, and FIG. 16 is a graph showing the relationship between engine load and EGR in combustion control. FIG. 17 is a map showing the relationship between engine speed and EGR rate in combustion control.

As shown in FIG. 9, when combustion control is started, first in step S301, the PCM 84 generates a desired electric power based on the SOC input from the BCM 80 and the accelerator opening input from the accelerator opening sensor 82. The output of the rotor housing 16 (required engine output) required to cause the starter generator 10 to generate electricity is calculated. Specifically, the PCM 84 refers to a map (preset and stored in advance) that defines the relationship between SOC, accelerator opening, vehicle speed, and required engine output, and calculates the SOC, accelerator opening, and Calculate the required engine output corresponding to the vehicle speed. In the above map, for example, the higher the vehicle speed or the greater the accelerator opening, the greater the required engine output.

Next, in step S302, the PCM 84 calculates the rotation speed (required engine rotation speed) and load (required engine load) of the rotary engine 14 necessary to obtain the required engine output calculated in step S301, and outputs them to the ECM 70. . Specifically, the PCM 84 refers to a map (set and stored in advance) that defines the relationship between the requested engine output, the requested engine speed, and the requested engine load, and determines the relationship between the requested engine output calculated in step S301. The required engine speed and required engine load are calculated. In the above map, for example, the required engine load is set to be approximately constant, and the higher the required engine output, the higher the required engine rotation speed.

Next, in step S303, the ECM 70 supplies fuel to the injector 54 in one combustion cycle for each working chamber 24 in order to operate the rotary engine 14 at the required engine speed and required engine load input from the PCM 84. The number of times the fuel is injected (the number of fuel injections), the timing at which the fuel is injected (injection timing), and the amount of fuel to be injected (injection amount) are set.

FIG. 10 illustrates a pattern of fuel injection timing set by the ECM 70 according to the engine speed detected by the eccentric shaft angle sensor 58. In this FIG. 10, the horizontal axis shows the injection timing expressed by the eccentric shaft angle (EA), the upper row shows when the engine speed R is greater than the first revolution speed R1, and the middle row shows the case where the engine speed R is higher than the first rotation speed. When the engine rotation speed R is equal to or less than R1 and greater than the second rotation speed R2, the lower row shows the case where the engine rotation speed R is equal to or less than the second rotation speed R2. As illustrated in FIG. 10, the ECM 70 determines that the lower the engine speed R is, the greater the number of fuel injections in one combustion cycle in each of the working chambers 24, and the more the final fuel injection end timing is. The injector 54 is controlled to be retarded.

Specifically, the ECM 70 refers to a table (preset and stored in advance) that defines the relationship between the engine rotation speed and the number of fuel injections, as shown in FIG. Set the number of fuel injections corresponding to the engine speed. In the table shown in FIG. 11, when the engine rotation speed R is higher than the first rotation speed R1 (for example, 4000 rpm) (R1<R), the number of fuel injections is set to one. Further, when the engine rotation speed R is lower than the first rotation speed R1 and higher than the second rotation speed R2 (for example, 3000 rpm) (R2<R≦R1), the number of fuel injections is set to two. Further, when the engine rotation speed R is equal to or lower than the second rotation speed R2 (R≦R2), the number of fuel injections is set to three. In other words, the ECM 70 injects more fuel in one combustion cycle in each of the working chambers 24 when the engine speed R is less than or equal to the first rotation speed R1 than when the engine speed R is higher than the first rotation speed R1. In addition, when the engine rotation speed R is lower than the second rotation speed R2, which is lower than the first rotation speed R1, the working chamber 24 is The number of fuel injections is set so that the number of fuel injections in one combustion cycle for each of the following is increased.

In this way, the lower the engine speed R is, that is, the weaker the airflow in the working chamber 24, the more the number of fuel injections in one combustion cycle of each working chamber 24 is increased. Even if the airflow inside the fuel tank 24 is weak, the fuel can be evenly distributed from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

Further, the ECM 70 refers to a map (preset and stored in advance) that defines the relationship between the engine speed and the end timing of fuel injection, as shown in FIG. Set the fuel injection end time corresponding to the engine speed. In the map shown in Fig. 12, the horizontal axis represents the engine speed and the vertical axis represents the end time of fuel injection. The injection end time is represented by a dashed line.

As described above, when the engine rotation speed R is higher than the first rotation speed R1, the number of fuel injections is set to one, so the first injection end timing is the last fuel injection in one combustion cycle. It is time for injection to end. Furthermore, when the engine speed R is less than or equal to the first rotation speed R1 and higher than the second rotation speed R2, the number of fuel injections is set to two, so the second injection end timing is within one combustion cycle. This is the final fuel injection end time. Furthermore, when the engine speed R is less than or equal to the second rotation speed R2, the number of fuel injections is set to three, so the third injection end time is the last fuel injection end time in one combustion cycle. Become. In the map shown in FIG. 12, when the engine speed R is less than or equal to the first rotation speed R1 (when the number of fuel injections is 2 or 3), when the engine speed R is higher than the first rotation speed R1, The final fuel injection end timing (the second or third fuel injection end timing) is delayed compared to (when the number of fuel injections is one). In addition, when the engine speed R is less than or equal to the second rotation speed R2 (when the number of fuel injections is 3 times), when the engine speed R is higher than the second rotation speed R2 (when the number of fuel injections is 2 times), ), the final fuel injection end timing (third fuel injection end timing) is retarded. In other words, when the engine speed R is less than or equal to the first rotation speed R1, the ECM 70 controls the final combustion cycle of each of the working chambers 24 to In such a manner that the fuel injection end timing is retarded, and when the engine rotation speed R is lower than the second rotation speed R2 which is lower than the first rotation speed R1, than when the engine rotation speed R is higher than the second rotation speed R2. Also, the fuel injection amount is set so that the final fuel injection end timing in one combustion cycle of each of the working chambers 24 is retarded.

In this way, the lower the engine speed R is relatively, that is, the weaker the airflow in the working chamber 24, the more the end timing of the last fuel injection in each combustion cycle of the working chamber 24 is retarded. Therefore, even if the airflow in the working chamber 24 is weak, the fuel can be evenly distributed from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

The ECM 70 also stores a map (preset and stored) that defines the relationship between the fuel injection amount per combustion cycle (total fuel injection amount) for each working chamber 24 and the engine load (filling efficiency). With reference to this, the total fuel injection amount corresponding to the requested engine load input from the PCM 84 in step S302 is obtained. Furthermore, the ECM 70 refers to a map (preset and stored) that defines the relationship between the engine load (filling efficiency) and the fuel injection amount division ratio, as shown in FIG. 13, for example, and determines the required engine load. Get the corresponding split ratio. Then, by dividing the total fuel injection amount according to the obtained division ratio, the fuel injection amount for each injection is set. FIG. 13 is a map that defines the division ratio of the fuel injection amount when the engine speed R is less than or equal to the second rotation speed R2 (when the number of fuel injections is 3), where the horizontal axis is the engine load and the vertical axis is the It represents the division ratio of fuel injection amount. In FIG. 13, the split ratio for the first fuel injection is shown by a solid line, the split ratio for the second fuel injection is shown by a broken line, and the split ratio for the third fuel injection is shown by a dashed-dotted line. In the map shown in Fig. 13, the split ratio is set so that the higher the engine load, the larger the ratio of the injection amount of the first fuel injection, and the smaller the ratio of the second and third injection amounts. There is. Although not shown, a map that defines the division ratio of the fuel injection amount when the engine rotation speed R is higher than the second rotation speed R2 and lower than the first rotation speed R1 (when the number of fuel injections is 2) is The division ratio is set such that the higher the engine load, the larger the ratio of the injection amount of the first fuel injection, and the smaller the ratio of the second injection amount. In other words, the ECM 70 determines that when the engine speed R is equal to or lower than the first rotation speed R1, the higher the engine load at the same engine speed, the higher the amount of fuel injected in the first combustion cycle in each of the working chambers 24. The fuel injection amount is set so that the ratio of

At the same rotation speed, the higher the engine load, the greater the amount of fresh air flowing into the working chamber 24, and the stronger the airflow toward the leading side. Therefore, the proportion of the first fuel injection amount is increased and the fuel is injected toward the leading side. By increasing the amount of fuel in the fuel tank, it is possible to promote the mixing of the fresh air flowing to the leading side with the fuel and obtain a homogeneous air-fuel mixture.

Next, in step S304, the ECM 70 sets the opening degree of the EGR valve 50 based on the engine rotation speed detected by the eccentric shaft angle sensor 58 and the required engine load input from the PCM 84.

In the rotary engine 14, due to the rotation of the rotor 20, a squish flow flows in the working chamber 24 from the trailing side (the rear side in the rotor rotational direction) to the leading side (the forward side in the rotor rotational direction) during the combustion stroke. exist. Due to this squish flow, the flame generated by the ignition of the ignition plug 26 easily propagates to the leading side of the ignition plug 26, but is difficult to propagate to the trailing side. Therefore, when the spark plug 26 is ignited, the air-fuel mixture that exists on the trailing side of the spark plug 26 does not start combustion until it moves to the leading side of the spark plug 26 as the rotor 20 rotates. It has the characteristic that heat generation during the process occurs in two stages. That is, as illustrated in the graph of FIG. 14, in the combustion stroke of the rotary engine 14, first, the air-fuel mixture in the range from the vicinity of the spark plug 26 to the leading end of the working chamber 24 is heated. Main combustion (i) occurs as a result of combustion, and then second-stage combustion (ii) occurs as a result of combustion of the air-fuel mixture located on the trailing side of the spark plug 26 in the working chamber 24 .

As a result of research, the present inventors found that when exhaust gas is introduced into the intake air by an EGR device in a rotary engine, the proportion of second-stage combustion in heat generation during the combustion stroke changes depending on the EGR rate. The graph in FIG. 15 shows the relationship between the EGR rate and the proportion of second-stage combustion in heat generation during the combustion stroke. As shown in FIG. 15, when exhaust gas is introduced into the intake air by an EGR device in a rotary engine, the higher the EGR rate, the higher the proportion of second-stage combustion in heat generation during the combustion stroke. In the combustion control of this embodiment, the cooling loss of the rotary engine 14 is reduced by setting the EGR rate according to the engine rotation speed and engine load using the relationship between the EGR rate and the second stage combustion rate. The aim is to achieve both this and reduction of exhaust loss.

Specifically, the ECM 84 refers to a map (preset and stored in advance) that defines the relationship between engine load (filling efficiency) and EGR rate, as shown in FIG. Obtain the EGR rate corresponding to the input requested engine load. The map in FIG. 16 illustrates the relationship between engine load and EGR rate when the engine speed R is the same, with the horizontal axis representing the engine load and the vertical axis representing the EGR rate. According to the map of FIG. 16, the higher the engine load, the higher the EGR rate, and the smaller the rate of increase in the EGR rate.

When the engine load is relatively high, the pressure rise due to the main combustion occurring on the leading side of the working chamber 24 becomes steeper, so that the cooling loss tends to increase relatively. Therefore, as mentioned above, when the engine load is relatively high, compared to when the engine load is relatively low, by setting the EGR rate higher and increasing the proportion of second stage combustion, the main combustion Cooling loss can be reduced by slowing down the pressure rise. Further, as the engine load increases, by reducing the rate of increase in the EGR rate in response to the increase in engine load, it is possible to prevent exhaust loss due to second-stage combustion having a late combustion timing from becoming excessive.

Furthermore, when the engine load is relatively low, the cooling loss due to main combustion is small, so the influence of exhaust loss due to second stage combustion occurring after main combustion becomes relatively large. Therefore, when the engine load is relatively low, compared to when the engine load is relatively high, by setting the EGR rate lower and reducing the ratio of second-stage combustion, the exhaust gas caused by second-stage combustion can be reduced. Loss can be reduced.

Further, the ECM 84 refers to a map (preset and stored in advance) that defines the relationship between the engine speed and the EGR rate, as shown in FIG. Obtain the EGR rate corresponding to the number. The map in FIG. 17 illustrates the relationship between engine speed and EGR rate when the engine load is the same, with the horizontal axis representing the engine speed and the vertical axis representing the EGR rate. According to the map of FIG. 17, the higher the engine speed, the lower the EGR rate, and the smaller the rate of decrease in the EGR rate.

When the engine speed is relatively low, the squish flow flowing from the trailing side to the leading side in the working chamber 24 during the combustion stroke is relatively weak and flame propagation is slow, so the trailing side of the working chamber 24 Knocking is more likely to occur because the unburnt air-fuel mixture that remains in the engine self-ignites faster than the main combustion flame propagates. Therefore, when the engine speed is relatively low, the EGR rate is set higher than when the engine speed is relatively high, increasing the proportion of second-stage combustion, that is, reducing the proportion of main combustion. This makes it possible to moderate the pressure rise due to main combustion and suppress the occurrence of knocking. On the other hand, when the engine speed is relatively high and knocking is unlikely to occur, the EGR rate is set low to reduce the proportion of second-stage combustion, thereby reducing exhaust loss caused by second-stage combustion with a late combustion timing. can be reduced.

As described above, the ECM 70 acquires the EGR rate corresponding to the engine speed and the requested engine load, and uses a map or calculation formula (preset and stored) that defines the relationship between the EGR rate and the opening degree of the EGR valve 50. Based on this, the opening degree of the EGR valve 50 corresponding to the obtained EGR rate is set.

Next, in step S305, the ECM 70 sets the ignition timing by the spark plug 26 based on the engine rotation speed detected by the eccentric shaft angle sensor 58 and the required engine load input from the PCM 84. Specifically, the ECM 70 refers to a map (preset and stored) that defines the relationship between the ignition timing by the spark plug 26, engine speed, and engine load (filling efficiency), and uses the eccentric shaft angle sensor. The ignition timing is set in accordance with the engine rotational speed detected by step 58 and the required engine load input from the PCM 84 in step S302.

Next, in step S306, the rotary engine 14 is adjusted so that the number of fuel injections, fuel injection timing, and fuel injection amount set in step S303, the EGR valve opening degree set in step S304, and the ignition timing set in step S305 are achieved. The control amount of various devices such as the injector 54, spark plug 26, EGR valve 50, and throttle valve 36 is calculated, and electrical signals corresponding to the calculated control amounts are output to those devices. Control of these various devices is continued until the rotary engine 14 is operated at the requested engine speed and requested engine load input from the PCM 84. After step S306, the PCM 84 ends the combustion control and returns to the engine control shown in FIG. 4.

<Modified example>
Although the embodiments of the present invention have been described above, the specific configuration and means of the present invention can be modified and improved as desired within the scope of the technical idea of each invention described in the claims. . Hereinafter, such a modified example will be explained.

First, the problems to be solved by the invention and the effects of the invention are not limited to the above-mentioned contents, and the present invention can solve problems not described or produce effects not described. In addition, it may solve only a part of the described problem or produce only a part of the described effect.

In the embodiment described above, the case where the rotary engine 14 is installed in the series hybrid vehicle 1 has been described as an example, but the combustion control in this embodiment is applicable to the rotary engine 14 installed in a parallel hybrid vehicle, a split hybrid vehicle, or a non-hybrid vehicle. It can also be applied to engines.

<Action and effect>
Next, the effects of the series hybrid vehicle 1 and engine system 12 of this embodiment will be explained.

The ECM 70 of this embodiment is configured such that when the engine speed R is less than or equal to the first rotation speed R1, the engine speed R is higher than the first rotation speed R1 in one combustion cycle of each of the working chambers 24. The injector 54 is controlled so that the number of fuel injections is large and the final fuel injection end timing is delayed.

As a result, when the engine speed R is relatively low, that is, when the airflow in the working chamber 24 is relatively weak, the number of fuel injections in each combustion cycle of the working chamber 24 is increased, and the last fuel is By retarding the injection end timing, even if the airflow in the working chamber 24 is weak, the fuel can be distributed evenly from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

Furthermore, when the engine speed R is equal to or lower than the second rotation speed R2, which is lower than the first rotation speed R1, the ECM 70 controls each one of the working chambers 24 more than when the engine speed R is higher than the second rotation speed R2. The injector 54 is controlled so that the number of fuel injections in one combustion cycle is large and the injection end timing of the last fuel injection is delayed. As a result, the lower the engine speed R is, that is, the weaker the airflow in the working chamber 24, the greater the number of fuel injections in one combustion cycle in each of the working chambers 24, and the end of the last fuel injection. By retarding the timing, even when the airflow in the working chamber 24 is weaker, the fuel can be evenly distributed from the leading side to the trailing side, and a homogeneous air-fuel mixture can be obtained.

In addition, when the engine speed R is equal to or lower than the first rotation speed R1, the ECM 70 determines that the higher the engine load at the same engine speed, the higher the first fuel injection amount in one combustion cycle of each of the working chambers 24. The injector 54 is controlled so that the ratio becomes large. At the same engine speed, the higher the engine load, the greater the amount of fresh air flowing into the working chamber 24, and the stronger the airflow toward the leading side. By increasing the size and increasing the amount of fuel injected to the leading side, it is possible to promote the mixing of fresh air flowing to the leading side with fuel and obtain a homogeneous air-fuel mixture.

Particularly, in the series hybrid vehicle 1 in which the driving force of the rotary engine 14 is used only to drive the starter generator 10, in a region of high thermal efficiency, that is, a region where the engine speed R is relatively low and the airflow in the working chamber 24 is weak. The rotary engine 14 tends to be operated. Therefore, the engine system 12 of this embodiment, which can obtain a homogeneous air-fuel mixture even in a region where the engine speed R is relatively low and the airflow in the working chamber 24 is weak, is suitable for the series hybrid vehicle 1.

1 Series hybrid vehicle 2 Reducer 4 Drive wheel 6 Electric motor 8 Battery 10 Starter generator 12 Engine system 14 Rotary engine 16 Rotor housing 18 Side housing 20 Rotor 22 Eccentric shaft 24 Working chamber 26 Spark plug 28 Intake port 30 Exhaust port 32 Intake passage 34 Exhaust passage 36 Throttle valve 38 Throttle opening sensor 40 Air flow sensor 42 Air cleaner 44 EGR device 46 EGR passage 48 EGR cooler 50 EGR valve 52 EGR valve opening sensor 54 Injector 56 Metering oil pump 58 Eccentric shaft angle sensor 60 Intake pressure sensor 62 Intake air temperature sensor 64 Water temperature sensor 70 ECM
72 Processor 74 Storage unit 76 Voltage sensor 78 Current sensor 80 BCM
82 Accelerator opening sensor 84 PCM
86 SGCM

Claims (4)

a rotor housing, a side housing, a rotor housed in a rotor housing chamber surrounded by the rotor housing and the side housing and forming three working chambers, and an injector that injects fuel into one of the working chambers; a rotary engine having
a rotation speed sensor that detects the engine rotation speed of the rotary engine;
a controller configured to control fuel injection by the injector,
The controller is configured to control the number of times of fuel injection in one combustion cycle of each of the working chambers when the engine speed is less than or equal to a first speed than when the engine speed is higher than the first speed. and controlling the injector so that the final fuel injection end timing is delayed.
engine system. The controller is configured to control each of the working chambers to operate once in each of the working chambers when the engine speed is less than or equal to a second speed that is lower than the first speed than when the engine speed is higher than the second speed. controlling the injector so that the number of fuel injections in the combustion cycle is large and the injection end timing of the last fuel injection is delayed;
The engine system according to claim 1. When the engine rotation speed is equal to or lower than the first rotation speed, the controller may be arranged such that when the engine rotation speed is equal to or lower than the first rotation speed, the higher the load of the rotary engine at the same engine rotation speed, the higher the load of the rotary engine, the first combustion cycle in each of the working chambers. controlling the injector so that a proportion of the fuel injection amount is increased;
The engine system according to claim 1 or 2. A series hybrid vehicle comprising an electric motor as a driving force source and a generator capable of supplying electric power to the electric motor,
comprising the engine system according to claim 1 or 2,
the rotary engine drives the generator;
Series hybrid vehicle.

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