JP2006057472A - Multiple internal combustion engines - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiple internal combustion engine capable of reliably suppressing the backflow of exhaust gas to a sub engine that is stopped with a simple configuration.
When a sub-engine 2 is stopped in a multiple internal combustion engine having a single-cylinder sub-engine 2 independent of a main engine 1 and having exhaust pipes 17 and 27 merged on the upstream side of a catalyst 40. For example, the fuel supply from the fuel injection valve 24 is cut to fully open the throttle valve 23, to increase the lift amount of the intake valve, or to shift the closing timing toward the bottom dead center arrival side of the piston. Thus, by increasing the intake air amount and the actual compression ratio to increase the load on the piston in the compression stroke, the sub-engine 2 is stopped during the compression stroke in which both the intake valve and the exhaust valve are closed.
[Selection] Figure 1

Description

  The present invention relates to a plurality of internal combustion engines including sub engines independent from a main engine for traveling, and more particularly to stop control of the sub engines.

  Internal combustion engines are widely used as power sources for power generation and power, as well as power sources for vehicles and ships. In such an internal combustion engine, a technique is known in which a plurality of internal combustion engines are prepared and their operation / stop states are combined in order to increase the operation efficiency over a wide load range (see, for example, Patent Document 1).

In such a system using a plurality of internal combustion engines in common, a part of the exhaust system is often shared, but when there is another internal combustion engine that is stopped during operation of an internal combustion engine, There is a possibility that a reverse flow in which the exhaust of the engine flows into the stopped internal combustion engine may occur. In the technique of Patent Document 1, in order to suppress this backflow, a check valve and an electric valve are arranged in each exhaust passage to suppress backflow of exhaust gas to the stopped internal combustion engine.
JP-A-1-294910

  When the check valve and the electric valve are arranged in the exhaust passage in this way, the backflow of exhaust can be reliably suppressed, but there is a problem that the system configuration becomes complicated. Moreover, when these check valves and motor-operated valves are closed, the corresponding internal combustion engine cannot be operated. On the other hand, if an open failure occurs, the reverse flow cannot be stopped.

  Therefore, an object of the present invention is to provide a plurality of internal combustion engines that can reliably suppress the backflow of exhaust gas to a sub-engine that is stopped with a simple configuration.

  In order to solve the above problems, a multiple internal combustion engine according to the present invention is a multiple internal combustion engine including a main engine for traveling and an independent single-cylinder sub-engine. The fuel supply stop means for stopping the fuel supply to the fuel, and the load increase means for increasing the load on the piston of the sub-engine in the compression stroke after the fuel supply stop by the fuel supply stop means is provided. .

  When the fuel supply to the sub-engine is stopped, the sub-engine continues to be driven by inertia for a while, but eventually stops due to friction or the like. By increasing the load on the piston in the compression stroke after the fuel supply is stopped, the compression stroke cannot be terminated by inertia alone, and the sub-engine stops in the middle of the compression stroke.

  The load increasing means may increase the load on the piston by increasing the volume in the combustion chamber at the start of the compression stroke of the sub-engine. For example, the load at the time of the compression stroke is increased by increasing the actual compression ratio at the time of the compression stroke by shifting the timing of closing the intake valve to the bottom dead center side of the piston.

  Alternatively, the load increasing means may increase the load on the piston by increasing the density of air supplied to the combustion chamber of the sub-engine. For example, by fully opening the throttle valve or increasing the lift amount of the intake valve, the air density sent to the cylinder = the amount of air is increased to increase the load during the compression stroke.

  According to the present invention, since the sub engine is stopped in the middle of the compression stroke in which the exhaust valve and the intake valve are closed, it is possible to effectively suppress the exhaust from flowing into the combustion chamber of the sub engine from the exhaust system during the stop. . Further, since a special valve mechanism or the like is not required, backflow prevention can be realized with a simple configuration, and the reliability is increased.

  By performing control to increase the actual compression ratio and the intake air amount at the time of stopping, the probability that the sub-engine stops during the compression stroke is further improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  FIG. 1 is a schematic configuration diagram of a drive system of a vehicle including a plurality of internal combustion engines according to the present invention. This vehicle is provided with a sub-engine 2 for driving auxiliary equipment in addition to the main engine 1 for driving. Both the main engine 1 and the sub-engine 2 are internal combustion engines that use gasoline as fuel, for example, and the sub-engine 2 is an internal combustion engine that has a smaller displacement than the main engine 1. For example, the main engine 1 is a multi-cylinder type. On the other hand, the sub-engine 2 is a single cylinder type.

The main engine 1 is connected to an intake pipe 12 via an intake manifold 15 and an exhaust pipe 17 via an exhaust manifold 16. An air cleaner 11 and a throttle valve 13 are disposed on the intake pipe 12 from the upstream side, and fuel injection valves 14 are disposed downstream of the intake pipe 12 so as to correspond to the cylinders of the main engine 1. On the other hand, an exhaust purification catalyst 40 is disposed on the exhaust pipe 17, O ₂ sensors 42 and 43 are disposed on the upstream side and the downstream side, respectively, and a temperature sensor 41 is connected to the catalyst 40. . A muffler 44 is disposed on the downstream side of the catalyst 40. The output shaft of the main engine 1 is connected to the transmission 3, and the driving force is transmitted from the transmission 3 to driving wheels (not shown).

  An intake pipe 22 and an exhaust pipe 27 are connected to the sub-engine 2. An air cleaner 21, a throttle valve 23, and a fuel injection valve 24 are arranged on the intake pipe 22 from the upstream side in the same manner as the intake pipe 12 of the main engine 1. Is arranged. On the other hand, the exhaust pipe 27 is connected to a position upstream of the catalyst 40 in the exhaust pipe 17 of the main engine 1. Hereinafter, this connecting portion is referred to as a collecting portion 18. The output shaft of the sub-engine 2 is connected to a compressor or generator of an air conditioner (not shown) via an electromagnetic clutch 29, and drives auxiliary machinery.

  FIG. 2 is a schematic configuration diagram of the sub-engine 2 main body. The sub-engine 2 includes a cylinder block 200 in which a cylinder 201 is formed, and a cylinder head 210 fixed to the upper part of the cylinder block 200. A crankshaft 220 is rotatably supported on the cylinder block 200. A piston 202 loaded in the cylinder 201 so as to be reciprocally movable in the vertical direction in the figure is connected to the crankshaft 220 by a connecting rod (connecting rod) 203, whereby reciprocating motion of the piston 202 is coupled to the crankshaft 220. Converted to rotational motion. The crankshaft 220 is provided with a crank angle sensor 215 that detects a crank rotation angle.

  A combustion chamber 204 is formed above the piston 202 surrounded by the top surface of the piston 202, the wall surface of the cylinder 201, and the bottom surface of the cylinder head 210. A spark plug 205 is attached to the bottom surface of the cylinder head 210 so as to face the combustion chamber 204.

  The connection port of the cylinder head 210 with the intake pipe 22 is opened and closed by an intake valve 206 supported by the cylinder head 210 so as to be able to advance and retract. The valve opening / closing timing and the lift amount of the intake valve 206 can be adjusted by an intake valve drive unit 208 provided in the cylinder head 210.

  Similarly, the connection port of the cylinder head 210 with the exhaust pipe 27 is opened and closed by an exhaust valve 207 supported by the cylinder head 210 so as to be able to advance and retract. The valve opening / closing timing and the lift amount of the exhaust valve 207 can be adjusted by an exhaust valve driving unit 209 provided in the cylinder head 210.

  The main engine 1 and the sub-engine 2 can be switched between an engaged state and a disengaged state by an electromagnetic clutch 80 and a belt drive 81. The main engine 1 and the sub engine 2 are engaged, and the main engine 1 can be started by the sub engine 2. The sub-engine 2 itself is started by the starter motor 70 by being engaged by the starter motor 70 and the electromagnetic clutch 71.

The main engine 1 and the sub engine 2 are controlled by the engine ECU 5. The engine ECU 5 includes a CPU, a ROM, a RAM, and the like. The outputs of the temperature sensor 41, the O ₂ sensors 42, 43, and the crank angle sensor 215 are input, and the throttle valves 13, 23, the fuel injection valve 14, 24, controls the operation of the intake valve / exhaust valve drive units 208 and 209 and the spark plug 205. Fuel is supplied from the fuel tank 6 to the fuel injection valves 14 and 24.

  The operation of this embodiment will be briefly described. First, at the start, the starter motor 70 and the sub-engine 2 are engaged by the electromagnetic clutch 71 and the sub-engine 2 is driven by the starter motor 70. When the rotational speed reaches a desired rotational speed, the fuel injection valve 24 Fuel is injected and ignition is performed by the spark plug 205 to start combustion of the sub-engine 2, thereby starting the sub-engine 2. After startup, the electromagnetic clutch 71 is disconnected and the drive of the starter motor 70 is stopped.

  The main engine 1 is engaged with the sub engine 2 by the electromagnetic clutch 80 and the belt drive 81, and the main engine 1 is driven by the sub engine 2. Similarly, when the desired rotational speed is reached, the fuel injection valve 14 supplies the fuel. Is started by injecting and starting combustion.

  When the vehicle travels, the driving force is transmitted from the main engine 1 to the driving wheels through the transmission 3. On the other hand, the sub-engine 2 drives an auxiliary machine or the like. When the vehicle is stopped due to a signal waiting or the like, the main engine 1 is stopped to suppress emission of exhaust gas and improve fuel efficiency. On the other hand, since the auxiliary machine such as an air conditioner is driven by the sub-engine 2, it is not necessary to drive the main engine 1 only for driving the auxiliary machine, and the main engine 1 is surely stopped when the vehicle is stopped. Can do. In addition, since the driving force of the main engine 1 can be used only for traveling even while the main engine 1 is operating, it is possible to set an appropriate driving condition according to the traveling state, and the responsiveness is also improved.

  The sub-engine 2 includes a case where it is not necessary to drive the auxiliary machine (a case where there is no load of the auxiliary machine and a case where the battery capacity is sufficient and the load of the auxiliary machine can be covered by power supply from the battery. ) May be stopped even while the main engine 1 is being driven. In addition, even when the auxiliary engine is driven by the main engine 1 rather than the auxiliary engine being driven by the sub engine 2, the electromagnetic clutch 80 is engaged and the electromagnetic clutch 29 is disconnected to stop the sub engine 2 even when the fuel efficiency is improved. There is a case to let you.

  Hereinafter, the control when the sub-engine 2 is stopped will be specifically described. FIG. 3 is a process flowchart of the sub-engine 2 stop control. This process is repeatedly executed by the engine ECU 5 at a predetermined timing while the sub-engine 2 is in operation.

  First, it is determined whether or not there is a request to stop the sub-engine 2 and a stop condition is satisfied (step S1). Here, the stop request is issued from, for example, the control circuit of the auxiliary machine when the driving load of the auxiliary machine falls below a predetermined level, and the main engine 1 is not stopped as a stop condition. What is necessary is just to set as a condition that the storage voltage of a battery is more than a predetermined level.

  If there is no stop request or the stop condition is not satisfied, the process is terminated as it is. In this case, the sub-engine 2 continues to operate. If there is a stop request and the stop condition is satisfied, the fuel supply from the fuel injection valve 24 is cut (step S2), and the throttle valve 23 is fully opened (step S3). By cutting the fuel supply, the sub-engine 2 continues to operate with inertia, but there is no energy generated in the expansion stroke, and the work and friction as a pump that sends air from the intake pipe 22 to the exhaust pipe 27 Due to the consumption of inertial energy, it stops.

  At this time, by fully opening the throttle valve 23, the amount of air and the air density sucked into the combustion chamber 204 are increased in the intake stroke. For this reason, the work amount that the piston 202 should perform in the compression stroke increases, and the consumption amount of inertial energy increases. Therefore, the piston 202 can be stopped early. Further, during the compression stroke, when the piston 202 reaches the top dead center (TDC) at the maximum compression ratio, the reaction force to the piston 202 is also maximized. By increasing this, the piston 202 is increased. During the compression stroke before reaching the top dead center, the movement of the piston 202 is stopped, and the sub-engine 2 is stopped.

  In step S4, the stop state is determined based on the output of the crank angle sensor 25. If the stop state is reached, the process is terminated. If the stop state has not been reached, the process returns to step S3, whereby the engine 2 is started. Make sure to stop.

  If the sub-engine 2 is stopped in the middle of the compression stroke in this way, both the intake valve 206 and the exhaust valve 207 are closed, so that the exhaust of the main engine 1 is exhausted from the exhaust pipe 17 through the collecting portion 18 and the exhaust pipe 27. There is no risk of entering the sub-engine 2, and it is also possible to suppress the exhaust from flowing into the intake pipe 22 side. Moreover, since it is realizable by control of the fuel injection valve 24 and the throttle valve 23, it is not necessary to add a new apparatus, and an apparatus structure does not become complicated. Since the exhaust pipes of the main engine 1 and the sub-engine 2 can be shared, the catalyst 40 and the muffler 44 can be shared, and emission can be improved.

  The stop control of the sub-engine 2 is not limited to the control of the throttle valve 23 as described above. Hereinafter, other control modes will be described. FIG. 4 is a flowchart of the second processing mode of the sub-engine 2 stop control.

  First, the sub-engine 2 stop request and stop condition determination (step S1), and the fuel supply cut from the fuel injection valve 24 (step S2) when the stop request and stop condition are satisfied are the processes described above. This is the same as the form (first processing form). After step S2, the intake valve drive unit 208 advances the closing timing of the intake valve 206 to control at the bottom dead center (BDC) of the piston 202 and increase the lift amount (step S13). FIG. 5 is a diagram for explaining the change of the intake valve profile by the intake valve drive unit 208. The normal closing timing is a time point slightly later than the piston 202 reaches the bottom dead center as shown by a broken line, but the control to bring this closer to the bottom dead center arrival time as shown by the solid line is controlled. Do.

  When the intake valve drive unit 208 can change only the valve opening and closing timing, the valve closing timing may be controlled to the bottom dead center position, and the intake valve drive unit 208 changes only the lift amount. If possible, it is sufficient to increase the lift. Also in this case, the fuel supply is cut, so that the sub-engine 2 continues to operate with inertia, but there is no energy generated in the expansion stroke, and the sub-engine 2 functions as a pump that sends air from the intake pipe 22 to the exhaust pipe 27. Stopping by consuming inertia energy due to work load and friction.

  At this time, by increasing the lift amount of the intake valve 206, the amount of air and the air density sucked into the combustion chamber 204 are increased in the intake stroke. In addition, by shifting the closing timing of the intake valve 206 toward the bottom dead center, the stroke amount at the start of the compression stroke, that is, the volume of the combustion chamber 204 is increased, thereby increasing the actual compression ratio.

  As a result, the work amount that the piston 202 should perform in the compression stroke increases and the consumption amount of inertial energy increases, so that the piston 202 can be stopped early. Further, during the compression stroke, the reaction force to the piston 202 is also maximized at the time when the piston 202 reaches the top dead center at the maximum compression ratio. By increasing this, the piston 202 reaches before the top dead center. During the compression stroke, the movement of the piston 202 is stopped, and the sub-engine 2 is stopped.

  Subsequently, as in the above embodiment, this stop state is determined based on the output of the crank angle sensor 25 (step S4). If the stop state is reached, the process is terminated. By returning to S13, the engine 2 is surely stopped.

  Also in this embodiment, the sub-engine 2 is stopped in the middle of the compression stroke so that both the intake valve 206 and the exhaust valve 207 are closed, so that the exhaust of the main engine 1 is discharged from the exhaust pipe 17 to the collecting portion 18 and the exhaust. There is no risk of entering the sub-engine 2 through the pipe 27, and furthermore, the exhaust can be prevented from flowing into the intake pipe 22 side. In the case of the sub-engine 2 having a variable valve timing mechanism that controls the closing timing of the intake valve 206 and a variable valve system that can change the lift amount, the present invention can be realized by these controls. There is no need to add a new device for control, and the device configuration is not complicated. Since the exhaust pipes of the main engine 1 and the sub-engine 2 can be shared, the catalyst 40 and the muffler 44 can be shared, and emission can be improved.

  Next, a third processing mode of the sub-engine stop control will be described with reference to the flowchart of FIG.

  First, the sub-engine 2 stop request and stop condition determination (step S1), the fuel supply cut from the fuel injection valve 24 when the stop request and stop condition are satisfied (step S2), the sub-engine 2 The process until the throttle valve 23 is fully opened (step S3) is the same as that in the first processing mode described above. Then, by performing the same process as step S13 of the second process form, the closing timing of the intake valve 206 is advanced, and the control is performed at the bottom dead center of the piston 202, and the lift amount is increased.

  When the intake valve drive unit 208 can change only the valve opening and closing timing, the valve closing timing may be controlled to the bottom dead center position, and the intake valve drive unit 208 changes only the lift amount. The same is true if the lift amount is increased if possible.

  Also in this case, the fuel supply is cut, so that the sub-engine 2 continues to operate with inertia, but there is no energy generated in the expansion stroke, and the sub-engine 2 functions as a pump that sends air from the intake pipe 22 to the exhaust pipe 27. Stopping by consuming inertia energy due to work load and friction.

  At this time, the lift amount of the intake valve 206 is increased and the throttle valve 23 is fully opened, thereby increasing the amount of air and the air density sucked into the combustion chamber 204 in the intake stroke. In addition, by shifting the closing timing of the intake valve 206 toward the bottom dead center, the stroke amount at the start of the compression stroke, that is, the volume of the combustion chamber 204 is increased, thereby increasing the actual compression ratio.

  As a result, the work amount that the piston 202 should perform in the compression stroke increases and the consumption amount of inertial energy increases, so that the piston 202 can be stopped early. Further, during the compression stroke, the reaction force to the piston 202 is also maximized at the time when the piston 202 reaches the top dead center at the maximum compression ratio. By increasing this, the piston 202 reaches before the top dead center. During the compression stroke, the movement of the piston 202 is stopped, and the sub-engine 2 is stopped.

  Subsequently, as in the above embodiments, this stop state is determined based on the output of the crank angle sensor 25 (step S4). If the stop has not been reached, the process returns to step S13, and the engine 2 Make sure to stop.

  When it is determined in step S4 that the engine is stopped, the process further proceeds to step S15 to determine whether the intake valve 206 and the exhaust valve 207 are securely closed. This determination may be performed based on the output of the crank angle sensor 215. If it is determined that both valves are closed, the process is terminated. If it is determined that one of the valves is open, the process proceeds to step S16, where the electromagnetic clutch 71 causes the sub-engine 2 and the starter to move. The motor 70 is engaged and the starter motor 70 is energized to drive the sub-engine 2. At this time, the driving force of the starter motor 70 is adjusted so that the sub-engine 2 cannot complete the compression stroke. That is, the electric power applied to the starter motor 70 may be controlled so that the piston 202 has a force that does not overcome the reaction force received from the compressed air in the combustion chamber 204 near the top dead center.

  Also in this embodiment, the same effect as the first and second processing forms described above can be obtained. Further, after confirming that the intake valve 206 and the exhaust valve 207 are closed, if the sub-engine 2 is stopped in any open state, the sub-engine 2 is driven by the starter motor 70 halfway through the compression stroke. Therefore, the stop state of the sub-engine 2 can be reliably set in the course of the compression stroke.

  Next, a fourth processing mode of the sub-engine stop control will be described with reference to the flowchart of FIG. In the fourth processing mode, as shown in FIG. 8, the sub-engine 2 includes a variable nozzle type turbocharger 28, the compressor 281 on the intake pipe 22 side, and the turbine 282 on the exhaust pipe 27. The two are connected by a drive shaft 283. And the vane 284 provided in the circumference | surroundings facing the turbine 282 employ | adopts the variable blade structure which can change the opening degree.

  First, the sub-engine 2 stop request and stop condition determination (step S1), the fuel supply cut from the fuel injection valve 24 when the stop request and stop condition are satisfied (step S2), the sub-engine 2 The processes until the throttle valve 23 is fully opened (step S3) and the engine stop determination (step S4) are the same as in the first processing mode described above.

  When it is determined in step S4 that the engine is stopped, the process further proceeds to step S25, and the vane 284 of the turbocharger 28 is closed. As a result, the same effect as when the exhaust pipe 27 is closed on the downstream side of the sub-engine 2 can be obtained.

  Also in this embodiment, the same effect as the first and second processing forms described above can be obtained. Further, since the exhaust pipe 27 is closed on the downstream side of the exhaust pipe 27, the backflow can be reliably prevented.

  Here, the case where the variable nozzle type turbocharger 28 is provided has been described, but an exhaust throttle valve may be disposed on the exhaust pipe 27 and closed to enhance the backflow prevention effect.

  Furthermore, the above first to fourth embodiments may be appropriately combined, or a part thereof may be replaced with another embodiment. In these combinations and replacement forms, the same effects as described above can be obtained.

  Here, the main engine 1 and the sub-engine 2 of the type in which gasoline is used as fuel and fuel is injected into the intake pipes 12 and 22 to form a premixed gas have been described. It is good also as an engine of the type which injects directly into. Further, the present invention can also be suitably applied to a plurality of internal combustion engines that use diesel engines or LPG (liquefied petroleum gas) as fuel.

It is a schematic block diagram of the drive system of the vehicle provided with the exhaust gas purification apparatus concerning this invention. It is a schematic block diagram of the sub-engine 2 main body of FIG. It is a processing flowchart of sub engine 2 stop control. It is a flowchart of the 2nd processing form of sub engine 2 stop control. It is a figure explaining the change of the intake valve profile by the intake valve drive part 208. FIG. It is a flowchart of the 3rd processing form of sub engine 2 stop control. It is a flowchart of the 4th processing form of sub engine 2 stop control. 2 is a schematic configuration diagram of a variable nozzle type turbocharger disposed in a sub-engine 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main engine, 2 ... Sub engine, 3 ... Transmission, 5 ... Engine ECU, 6 ... Fuel tank, 11, 21 ... Air cleaner, 12, 22 ... Intake pipe, 13, 23 ... Throttle valve, 14, 24 ... Fuel injection Valve 15, Intake manifold 16, Exhaust manifold 17, 27 Exhaust pipe 18, Collecting portion 25 Crank angle sensor 28 Turbocharger 40 Exhaust purification catalyst 41 Temperature sensor 42 O ₂ Sensor, 44 ... Muffler, 70 ... Starter motor, 71, 80 ... Electromagnetic clutch, 81 ... Belt drive, 200 ... Cylinder block, 201 ... Cylinder, 202 ... Piston, 204 ... Combustion chamber, 205 ... Spark plug, 206 ... Intake valve 207: Exhaust valve 208: Intake valve drive unit 209 ... Exhaust valve drive unit 210: Cylinder head 215 ... crank angle sensor, 220 ... crankshaft, 281 ... compressor, 282 ... turbine, 283 ... drive shaft, 284 ... vane.

Claims (3)

In a multiple internal combustion engine comprising a main engine for traveling and an independent single-cylinder sub-engine,
Fuel supply stopping means for stopping the fuel supply to the combustion chamber of the sub-engine in response to the sub-engine stop request;
Load increasing means for increasing the load on the piston of the sub-engine in the compression stroke after stopping the fuel supply by the fuel supply stopping means;
A plurality of internal combustion engines.   2. The multiple internal combustion engine according to claim 1, wherein the load increasing means increases the load on the piston by increasing the volume in the combustion chamber at the start of the compression stroke of the sub-engine.   2. The multiple internal combustion engine according to claim 1, wherein the load increasing means increases a load on the piston by increasing an air density supplied to a combustion chamber of the sub-engine.

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