JPH11125121A - Operation control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform assistance for starting an engine or promotion for warming it up, by giving braking force or reverse rotation to an exhaust turbine provided in an exhaust pipe, at the time of starting the engine or its warming operation. SOLUTION: In an exhaust turbine 3 provided in an exhaust pipe 2 where exhaust gas flows from an engine 1, a generator 4 is connected. When an electronic control unit judges that the engine is started or operated to be warmed up, a magnet contactor 18 provided in a three-phase AC output line 5 of the generator 4 is operated, and a winding terminal of the generator 4 is short- circuited. Braking force is generated in the rotary shaft of the generator 4, the rotation of the exhaust turbine 3 is slowed. Accordingly, the back pressure of the engine 1 is increased, the cylinder pressure of the engine 1 and its temperature are increased, assistance for starting the engine 1 and promotion for warming it up are devised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for an engine in which a turbine having an AC machine is disposed in an exhaust pipe for recovering thermal energy of exhaust gas discharged from the engine and flowing through the exhaust pipe.

[0002]

2. Description of the Related Art Conventionally, as a diesel engine, for example, there is a ceramic engine using ceramics capable of withstanding high heat for an outer wall of an exhaust manifold, a cylinder liner, a cylinder head heat insulating plate, a piston, and the like.
Since a ceramic engine does not require cooling of the engine, it is advantageous to recover the thermal energy of the generated high-temperature exhaust gas and use it for improving the output of the engine. Means for recovering the thermal energy of the exhaust gas include a turbine having a generator provided in an exhaust pipe or a turbocharger having a generator. The turbine rotates by the flow of hot exhaust gas, and its driving force is transmitted directly to the crankshaft and other equipment, or used to operate a generator to convert the heat energy of the exhaust gas into electric energy. Can be When the generator is operated by the rotation of the turbine, the generated electric power is supplied to the electric motor, and the crankshaft and the rotating shaft of another device are electrically operated. Japanese Patent Application Laid-Open No. 62-276210 discloses that an exhaust pipe of an exhaust gas turbine is connected in series with a high-pressure exhaust turbine and a low-pressure exhaust turbine each having a generator, and assists the driving force of the driving shaft of the engine. There is disclosed an engine in which a generator having two windings, which is a means for performing the operation, is mounted, and the output from each generator is supplied to the two windings.

As an automatic starting device for a diesel engine, detection signals of an engine temperature sensor, an engine speed sensor, a load lever position sensor of a fuel injection device, and a throttle degree sensor of an exhaust pipe or an intake pipe are input to an input signal. And a load lever adjusting device for moving a load lever position of a fuel injection device of the engine, an actuator for adjusting the degree of throttle of an exhaust pipe or an intake pipe, and starting the engine in accordance with each detection signal. There has been proposed a starting device for a diesel engine in which each operation of a starter is automatically controlled with time (see Japanese Patent Publication No. 3-61818). According to the starting apparatus for a diesel engine, an actuator capable of restricting an exhaust pipe or an intake pipe in a cold season is provided, and information on the degree of restriction of the exhaust pipe or the intake pipe is added as information necessary for starting the engine. By automatically setting the optimal starting conditions, the starting operation of the diesel engine is simplified. That is, when the temperature detected by the temperature sensor at the time of starting the engine is low, the exhaust pipe is closed to allow the combustion gas to stay in the combustion chamber and raise the engine temperature. Is shortening the time.

[0004]

By the way, if the back pressure of the engine can be increased by using a device provided in connection with the exhaust pipe of the engine, for example, a turbine having a generator or a turbocharger having a generator, Similar to closing the exhaust pipe, the temperature of the combustion chamber can be raised by retaining the combustion gas in the combustion chamber.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and an exhaust turbine is provided in an exhaust pipe for recovering energy of exhaust gas and converting the energy into electric energy. Focusing on this, when starting the engine or warming up the engine, the turbine is used to provide resistance to the flow of exhaust gas flowing through the exhaust pipe, or to positively generate a reverse flow. In this case, the in-cylinder pressure is increased by increasing the back pressure of the engine, and as a result, the temperature in the combustion chamber is increased to improve the starting performance of the engine and to promote the warm-up operation.

[0006] In order to achieve the above object, the present invention is configured as follows. That is, the present invention relates to an operation control device for an engine in which a turbine having an AC machine is disposed in the exhaust pipe for recovering thermal energy of exhaust gas discharged from the engine and flowing through the exhaust pipe. Detecting whether the engine is in a start-up or a warm-up operation based on the detection means for detecting and the operating state of the engine detected by the detection means; A controller for applying a braking force to the turbine or rotating the AC machine as a motor in a direction opposite to the direction in which the exhaust gas rotates, and applying a braking force to the turbine. Or an engine wherein the back pressure of the engine is increased by rotating the AC machine in the reverse direction to increase the in-cylinder temperature. About the driving control device.

In this operation control device for an engine, a braking force is applied to the turbine by short-circuiting a winding terminal of the AC machine. The short circuit of the winding terminals of the alternator is performed by connecting the winding terminals of the alternator with a magnet contactor, and by using a brake circuit for preventing over-rotation of the alternator incorporated in the inverter connected to the winding terminals. This can be done by short-circuiting, or by short-circuiting the inverter converter connected to the winding terminal.

In the engine operation control device, the magnitude of the braking force applied to the turbine is controlled by the reverse conversion of the magnet contactor, the brake circuit, or the inverter in order to cause a short circuit between winding terminals. It can be changed by changing the duty ratio of the switching signal supplied to the device. Switching signal is O
Assuming that the short circuit is caused in the N state, if the ON state of the switching signal is long, the time during which the winding terminals are short-circuited becomes long, and the braking force applied to the turbine increases.

In this operation control device for an engine, in order to drive the AC machine as a motor in a direction opposite to the direction of rotation by the exhaust gas, the inverter connected to the winding terminal is a bidirectional inverter. This is done by supplying power to the alternator through a bidirectional inverter.

[0010] In this engine operation control device, it is usually determined that the engine is being started when the ignition key is turned ON. Alternatively, if the ignition key only depends on being turned ON, there is a possibility of malfunction, so the ignition key is
N, the engine is started when the shift gear position is at the neutral position or the parking position and / or the side brake lever position is at the operating position. Is determined.
From the viewpoint of the detection means and the detection signal, the detection means is an ignition key sensor, and the controller determines that the engine is started at the time when the detection signal of the ignition key sensor is an ON signal of the ignition key. . Alternatively, the detection means is an ignition key sensor, a transmission gear position sensor, and a side brake lever position sensor. In addition to the detection signal of the ignition key sensor being an ON signal of the ignition key, the detection signal of the transmission gear position sensor is provided. Depending on whether the signal is the neutral position signal or the parking position signal of the transmission gear position, or whether the detection signal of the side brake lever position sensor is the side brake lever operating position signal (of course, both may be established), the controller determines It is determined that the engine is starting.

In the engine operation control device, when the temperature of the engine after starting the engine is equal to or lower than a predetermined temperature and the rotational speed of the engine is equal to or lower than the predetermined speed, the engine is warmed up. It is determined that the machine is operating. After the engine is started, if the above conditions for the temperature and the engine speed are satisfied, it is determined that the engine is in the warm-up operation and the operation shifts to the warm-up operation, and the in-cylinder temperature of the engine is increased by increasing the in-cylinder pressure of the engine. The ascending operation is continued.

Further, in the engine operation control device, the braking force applied to the turbine decreases as the temperature of the engine increases. If the temperature of the engine rises, warm-up operation is nearing completion,
The need to accumulate combustion gases in the cylinder is reduced, and the braking force applied to the turbine is reduced.

According to the present invention, as described above, in an operation control device for an engine in which a turbine having an AC machine is arranged in the exhaust pipe to recover thermal energy of exhaust gas discharged from the engine and flowing through the exhaust pipe, When it is determined that the engine is being started or warming up, the exhaust pipe is removed by applying braking force to the turbine or by driving the AC machine as a motor in the direction opposite to the direction of rotation by the exhaust gas. The engine's starting performance is improved because the engine's back pressure is increased by restricting the emission of combustion gas, and the combustion gas is retained in the combustion chamber to increase the in-cylinder pressure and in-cylinder temperature of the engine. The warm-up operation is promoted.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing one embodiment of an engine operation control device according to the present invention.
In FIG. 1, the combustion gas discharged from each cylinder of the engine 1 is collected by an exhaust manifold and then discharged through an exhaust pipe 2. A turbine 3 having a generator 4 is arranged in the exhaust pipe 2, and the turbine 3 is driven to rotate by the energy of the exhaust gas. The generator (turbine generator) 4 is driven by the turbine 3, and the generated electric energy is converted into a three-phase AC through, for example, an output line 5 connected to each winding terminal (not shown) of the generator 4. Used to drive other equipment.

An electronic control unit (ECU) 6 for controlling the engine 1 performs signal processing by receiving an I / O unit 7 to which detection signals from various sensors are input and a signal from the I / O unit 7. A CPU 8, a memory 9 for storing information processed by the CPU 8 based on detection information of each sensor or information from each sensor, or providing the stored information to the CPU 8, and an output signal from the CPU 8 to the outside of the electronic control unit 6; And an output I / O unit 10. The I / O unit 7 includes an engine temperature signal indicating the current temperature of the engine from the temperature sensor 11, a gear position signal indicating the current position of the shift gear from the shift gear position sensor 12, and a side position signal from the side brake position sensor 13. A side brake position signal indicating the current position of the brake, an engine speed signal indicating the current number of revolutions of the engine from the engine speed sensor 14, and whether or not the ignition key of the engine from the ignition sensor 15 has been operated for ignition. The ignition signal is input. The output of the I / O unit 10 is output to the relay 16.

The relay 16 is provided on a wiring connecting between the battery 17 and the output line 5 connected to the three-phase AC terminal. The ECU 6 turns on the relay 16 as an output signal.
When N is set, the magnet contactor 18 provided between the output lines 5 connected to the winding terminals operates. When the magnet contactor 18 operates, the terminals of the windings are simultaneously short-circuited.

When the engine is started, the following items are determined by the ECU. Based on the engine temperature signal from the temperature sensor 11, it is determined whether or not the current engine temperature is equal to or lower than a predetermined temperature. Based on the gear position signal from the transmission gear position sensor 12 indicating the current position of the transmission gear, it is determined whether the vehicle is at the parking position or the neutral position. It is determined whether or not the side brake is ON based on a side brake position signal indicating the current position of the side brake from the side brake position sensor 13.
Based on the engine speed signal from the engine speed sensor 14, it is determined whether the current engine speed is equal to or less than a predetermined engine speed. Then, based on the ignition signal from the ignition sensor 15, it is determined whether or not the ignition key of the engine is operated for ignition.

Whether or not the engine has been started is basically determined based on an ignition signal from an ignition sensor 15 which outputs a signal corresponding to an operation of an ignition key. However, as a countermeasure against malfunction, at least one of a gear position signal indicating the current position of the shift gear from the shift gear position sensor 12 and a side brake position signal indicating the current position of the side brake from the side brake position sensor 13 is also used. Used. If it is determined that the engine is not in the predetermined stable operating state after the start or the start of the engine, EC
U6 outputs to the relay 16 to output the magnetic contactor 1
8 is operated to short-circuit between the winding terminals of the generator 4. When the winding terminals are short-circuited, short-circuit braking is applied to the generator 4 as an electromagnetic characteristic of the generator 4. Therefore,
The turbine 3 that drives the generator 4 gives flow resistance to the exhaust gas flowing through the exhaust pipe 2. The exhaust gas does not flow smoothly in the exhaust pipe 2 due to the flow resistance, and the back pressure increases and the in-cylinder pressure also increases. When the pressure in the cylinder increases, the combustion gas is not completely scavenged from the combustion chamber during the scavenging process, but stays in the combustion chamber. As a result, the temperature in the cylinder increases and the fuel easily ignites, improving the engine startability. I do.

FIG. 2 is a schematic diagram showing another embodiment of the engine operation control device according to the present invention. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG. 1 to omit redundant description. An inverter 21 is connected to each of the three-phase AC output lines 5 connected to each winding terminal of the generator 4, and a brake circuit 22 for preventing the generator 4 from over-rotating is provided in the inverter 21. ing.
When the ECU 6 determines that the engine is not in a predetermined stable operating state since the engine is currently started or started, the E
The CU 6 outputs a switching signal to the output line 20 to operate the overspeed prevention brake circuit 22 in the inverter 21. The over-speed prevention brake circuit 22 has the same function as short-circuiting between the output lines 5, that is, between the winding terminals of the generator 4, and short-circuits and brakes the generator 4. In FIG. 2, the freewheeling diode for performing switching control of the inverse converter 23 (inverter arm) of the inverter 21 is omitted.

FIG. 3 is a schematic diagram showing another embodiment of the engine operation control device according to the present invention. Of the constituent elements shown in FIG. 3, the same constituent elements as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. The example shown in FIG.
As compared with the example shown in FIG. 1, the inverter 21 does not have the brake circuit 22 for preventing the
The difference from the CU 6 is that a switching signal for operating the inverter 23 (inverter arm) of the inverter 21 is output to the output line 24. ECU6
However, when it is determined that the engine is not in a predetermined stable operating state after the start or the start of the engine, the inverter 23 of the inverter 21 is operated by the switching signal output by the ECU 6, and the output lines of the three-phase AC are output. 5, that is, a state where the winding terminals of the generator 4 are short-circuited, and the generator 4 is short-circuited and braked.

FIG. 4 is a schematic diagram showing still another embodiment of the engine operation control device according to the present invention. 4, the same components as those shown in FIG. 2 are denoted by the same reference numerals as those shown in FIG. 1, and redundant description will be omitted. The example shown in FIG.
Compared to the example shown in FIG. 2, the inverter 31 is a bidirectional inverter, and when a driving current is supplied from the outside,
The generator 4 can work as a motor. That is,
The inverter 31 includes an inverter arm unit 32 that can function as both a forward converter and an inverse converter combining a plurality of transistors as switching elements instead of diodes. ECU6
Outputs a switching signal for controlling the switching operation of the inverter arm unit 32 through the output line 33.
The inverter arm 32 normally functions as a forward converter of the inverter 31. When increasing the back pressure of the exhaust gas at the time of starting or the like, the inverter arm 32 converts a current from the battery 17 as a DC power supply into an AC and converts it into an AC. It functions as an inverter that supplies three-phase alternating current to the generator 4. When the inverter arm 32 operates the generator 4 as an electric motor, the booster circuit 35 boosts the voltage of the battery 17. The booster circuit 35 is operated by a control signal from an output line 34 from the ECU 6.

When the ECU 6 determines that the engine is currently started or is not in a predetermined stable operation state after starting, the voltage of the battery 17 is increased by the signal output from the ECU 6 to the output line 34. The voltage is boosted by 35 and the switching signal output to the output line 33 activates the inverter arm 32 of the inverter 21 to supply the current from the booster circuit 35 to the generator 4 as three-phase alternating current. The generator 4 operates as an electric motor, and rotates the turbine 3 in a direction opposite to the direction in which the exhaust gas rotates the generator 4, that is, a direction in which the exhaust gas is pushed back.

The engine operation control device according to the present invention can be used for promoting the warm-up operation of the engine. When the engine temperature is equal to or lower than the predetermined temperature and the engine speed is equal to or lower than the engine speed determined as the idling engine speed, the ECU 6 determines that the engine is in the warm-up operation state. Also at this time, the winding terminals of the generator 4 connected to the turbine 3 are short-circuited, the braking force is applied to the turbine 3 and the exhaust resistance against the flow of the exhaust gas is increased.
Increase the temperature in the combustion chamber. In order to promote the warm-up operation, only the ON / OFF control of the magnet contactor 18 can be performed in the first embodiment among the above-described embodiments. Therefore, the second to fourth embodiments are preferable. When the fourth embodiment is applied to a warm-up operation, the inverter arm 32 is controlled by using an inverter as in the third embodiment instead of using the generator 4 to operate the motor. It is preferable to use a method of short-circuiting the arm 32.
During the warm-up operation, the engine operates independently,
If the exhaust resistance given to the exhaust gas is excessively increased, the combustion is deteriorated.

As the control of the switching signal output by the ECU 6, it is preferable to perform control over time as shown in FIG. That is, in the start assist period ΔTa from the time T0 when the ignition turns ON to the start of the warm-up at the time T1, the switching signal in the ON state is output in a full time, the start assist is finished, and the warm-up promoting operation is performed. When shifting, the warm-up start time T1 to the warm-up end time T
In the warm-up promotion period ΔTb up to 2, duty ratio control for changing the time width during which the switching signal is ON is performed.
Specifically, the temperature of the engine, that is, the temperature of the engine cooling water in a water-cooled engine, and the temperature of the cylinder head and the like in an engine that does not use cooling water such as a ceramics engine are detected, and are detected over time. As the temperature gradually rises, the switching signal becomes O
Control is performed to gradually narrow the time width of N. Exhaust resistance given to exhaust gas by the turbine 3 gradually decreases. That is, since it is not necessary to increase the temperature of the combustion chamber as the warm-up operation approaches the end, the short-circuit time of the output terminal of the generator 4 is shortened, and control is performed to gradually reduce the degree of increase in the back pressure of the engine. . When the detected temperature is equal to or lower than the reference value, it is determined that the temperature is low. By providing the reference value with a certain width, it is possible to prevent a hunting phenomenon in which the temperature greatly fluctuates in the temperature control. The reference value and the temperature hysteresis width are stored in the memory 9 in the ECU 6. Although the generator 4 has been described as being a three-phase AC generator, it is clear that the type of the generator 4 is not limited to this, and may be a single-phase AC generator.

[0025]

Since the present invention is configured as described above, it has the following effects. That is, according to the engine operation control device of the present invention, the exhaust resistance given to the exhaust gas by the turbine disposed in the exhaust pipe is more positively increased than in the normal operating state for energy recovery. As a result, the back pressure of the engine is increased to increase the in-cylinder pressure, that is, the in-cylinder temperature, so that the engine can be easily started and the warm-up operation of the engine can be promoted. Moreover, in order to increase the exhaust resistance of the exhaust gas in the exhaust pipe at the time of starting or the like, a new component such as a throttle valve is not required only for the purpose of, for example, closing the exhaust pipe. It is only necessary to control the operation of the turbine arranged to recover energy, and it is possible to suppress an increase in cost. When the exhaust pipe is mechanically throttled like a throttle valve, it is difficult to fine-tune the control and it is easy to fail. However, the short-circuit control of the generator connected to the turbine is controlled by the switching duty ratio. Therefore, the back pressure of the engine can be controlled accurately and stably.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an engine operation control device according to the present invention.

FIG. 2 is a schematic diagram showing another embodiment of the engine operation control device according to the present invention.

FIG. 3 is a schematic diagram showing another embodiment of the engine operation control device according to the present invention.

FIG. 4 is a schematic diagram showing still another embodiment of the engine operation control device according to the present invention.

FIG. 5 is a diagram illustrating a change over time of a switching signal of an ECU in the engine operation control device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 2 exhaust pipe 3 turbine 4 generator 5 output line 6 electronic control unit (ECU) 11 temperature sensor 12 shift gear position sensor 13 side brake position sensor 14 engine rotation speed sensor 15 ignition sensor 18 magnet contactor 21, 31 inverter 22 excess Anti-rotation brake circuit 23, 32 Inverter arm

Claims (9)

[Claims] 1. An engine operation control device in which a turbine having an AC machine is disposed in an exhaust pipe for recovering thermal energy of exhaust gas discharged from the engine and flowing through an exhaust pipe, the operating state of the engine being detected. And determining whether the engine is in a start-up or warm-up operation based on the operating state of the engine detected by the detection means. If it is determined that there is a braking force, the controller may be provided with a controller for applying a braking force to the turbine or rotating the AC machine as a motor in a direction opposite to a direction in which the exhaust gas rotates, and applying a braking force to the turbine. Or an operation of the engine, wherein the back pressure of the engine is increased by rotating the AC machine in a reverse direction to increase the in-cylinder temperature. Control device. 2. The engine operation control device according to claim 1, wherein the braking force is applied to the turbine by short-circuiting between winding terminals of the AC machine. 3. A short circuit between the winding terminals is achieved by connecting the winding terminals of the AC machine with a magnet contactor, and by over-rotating the AC machine incorporated in an inverter connected to the winding terminals. 3. The engine operation control device according to claim 2, wherein the operation is performed by short-circuiting a brake circuit for preventing the occurrence of a short-circuit, or short-circuiting an inverter connected to the winding terminal. 4. The magnitude of the braking force applied to the turbine is determined by the switching supplied to the inverter of the magnet contactor, the brake circuit, or the inverter to cause a short circuit between the winding terminals. 4. The engine operation control device according to claim 3, wherein the change can be made by changing a duty ratio of the signal. 5. An inverter connected to the winding terminal is a bidirectional inverter, and the power supplied through the bidirectional inverter causes the AC machine to rotate as the electric motor in a direction opposite to a direction rotated by the exhaust gas. The operation control device for an engine according to claim 1, wherein the operation control device is driven. 6. The controller according to claim 1, wherein the detection means is an ignition key sensor, and the controller determines that the engine is in the starting state when the detection signal of the ignition key sensor is an ON signal of an ignition key. The operation control device for an engine according to any one of claims 1 to 5. 7. The detecting means includes the ignition key sensor, the speed change gear position sensor, and the side brake lever position sensor, wherein the detection signal of the ignition key sensor is an ignition key ON signal, and the speed change gear position sensor Is the neutral position signal or the parking position signal of the transmission gear position, or the detection signal of the side brake lever position sensor is the side brake lever operation position signal, so that the controller can determine when the engine is started. The operation control device for an engine according to any one of claims 1 to 5, wherein the determination is made. 8. When the temperature of the engine after the start of the engine is equal to or lower than a predetermined temperature and the rotation speed of the engine is equal to or lower than a predetermined speed, the engine is operated during the warm-up operation. The engine operation control device according to any one of claims 1 to 5, wherein it is determined that: 9. The engine operation control device according to claim 8, wherein the braking force applied to the turbine is reduced as the temperature of the engine increases.