JP2005155526A - Cylinder pressure control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder pressure control device of an internal combustion engine having a compact structure in which pumping loss is reduced and a power-saving can be achieved. <P>SOLUTION: An intake passage 4 and an exhaust passage 5 are connected to an engine 1. The cylinder pressure control device is provided with communication ports 24 and a communication pipe 26 of which one end is allowed to communicate with each of a plurality of cylinders 2, and the other end thereof is allowed to communicate with the intake passage 4, solenoid valves 25 provided to respective communication ports 24, a revolution speed sensors 33 for detecting operation stroke of each cylinder 2, and a control unit 40. When the control unit 40 has judged on the basis of detection results of the operation stroke that a certain cylinder 2 is on a compression stroke, the control unit 40 controls a corresponding solenoid valve 25 so as to reduce the pressure in the combustion chamber 14 of the cylinder 2. On the basis of operation conditions detected by sensors 31-34, the control unit 40 computes timings for opening and closing the respective solenoid valves 25, and controls the period of time of the each solenoid valve 25 being open on the basis of the computed timing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an in-cylinder pressure control device that controls pressure in a cylinder of an internal combustion engine in order to reduce pump loss.

  In conventional gasoline engines, pump loss occurs. The pump loss refers to a combination of an intake loss that occurs when the engine sucks air necessary for working outside and an exhaust loss that occurs when the already burned gas is discharged to the outside. FIG. 6 shows a PV diagram at full load. FIG. 7 shows a PV diagram at the time of partial load. In both FIGS. 6 and 7, the shaded portion corresponds to the pump loss.

Here, the following Non-Patent Document 1 describes the pump loss as follows. That is, in a gasoline engine, the output is controlled by a throttle valve, so that pump loss occurs due to throttle loss in this valve. In particular, the smaller the load, the greater the pump loss, causing a reduction in combustion efficiency at low loads.
On the other hand, since the diesel engine controls the load by the fuel injection amount with a constant air amount (no throttle valve), there is no pump loss even at low loads, and high efficiency is obtained (because the air-fuel mixture becomes dense at high loads) Heat efficiency is reduced).

  Therefore, it is conceivable to eliminate the throttle valve (throttle valve) in the intake passage even in a gasoline engine. In this case, instead of eliminating the throttle valve, another configuration for adjusting the intake air amount is required. In Patent Document 1 below, an electromagnetically driven intake valve is provided in a valve operating system mechanism, and the opening loss period of the electromagnetically driven intake valve is finely controlled according to the operating state of the internal combustion engine, thereby reducing pump loss. It is described. The electromagnetically driven intake valve is an intake valve that can be opened and closed by electromagnetic force generated by a solenoid. Therefore, in an internal combustion engine in which the throttle valve is eliminated from the intake passage, it is conceivable to control the valve opening period by providing an electromagnetically driven intake valve in the valve operating mechanism.

JP-A-9-88645 (page 3, FIG. 2) Edited by Yasuo Nakajima and Shigeo Nakamura, “New Gasoline Engine for Automobiles”, Sankai-do, published on March 31, 1996, p. 47-48

  However, in the electromagnetically driven valve control device described in Patent Document 1, since the suction force necessary for operating the electromagnetically driven intake valve is relatively large, the power supplied to the solenoid also becomes great. For this reason, a large load is applied to the power source to secure electric power, and at that time, there is a possibility that torque loss occurs in the internal combustion engine. In addition, a solenoid must be provided for each intake valve, which increases the size and weight of the device. In particular, in a multi-cylinder internal combustion engine, solenoids or the like must be provided on a large number of intake valves, and the occupied space in the internal combustion engine of the apparatus becomes a problem.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an in-cylinder pressure control device for an internal combustion engine that can reduce pump loss with a compact structure and can save labor. It is in.

  In order to achieve the above object, an invention according to claim 1 is an in-cylinder pressure control device for controlling a pressure in a cylinder in an internal combustion engine having an intake passage connected thereto. The cylinder is compressed based on the detected operation stroke, the communication passage whose end communicates with the intake passage, the opening / closing means provided for opening / closing the communication passage, the operation stroke detecting means for detecting the operation stroke of the internal combustion engine The purpose of the present invention is to provide a control means for controlling the opening / closing means in order to reduce the pressure in the cylinder when it is determined that it is in the stroke.

  According to the configuration of the above invention, when the control unit determines that the cylinder is in the compression stroke based on the operation stroke of the internal combustion engine detected by the operation stroke detection unit, the control unit is provided in the communication path communicating with the cylinder. Open by controlling the opening and closing means. Accordingly, the pressure in the cylinder that becomes the compression stroke is released to the intake passage, and the pressure in the cylinder is reduced.

  In order to achieve the above object, the invention according to claim 2 is the invention according to claim 1, wherein the operation state detecting means for detecting the operation state of the internal combustion engine and the opening and closing based on the detected operation state are provided. Opening / closing timing calculating means for calculating the opening timing and closing timing of the means, and the control means controls the opening / closing means based on the calculated opening timing and closing timing.

  According to the configuration of the invention described above, in addition to the operation of the invention according to claim 1, the operating state detecting unit detects the operating state of the internal combustion engine, so that the opening / closing timing calculating unit is based on the detected operating state. Calculate the opening time and closing time. Based on the calculated opening timing and closing timing, the control means controls the opening / closing means. Here, the pressure in the cylinder in the compression stroke differs depending on the operating state of the internal combustion engine. Therefore, since the opening timing and closing timing of the opening / closing means are controlled according to the operating state, the pressure in the cylinder efficiently escapes to the intake passage according to the operating state.

  In order to achieve the above object, according to a third aspect of the present invention, in the first or second aspect of the present invention, the internal combustion engine has a plurality of cylinders, and a communication path is provided for each of the cylinders. And the opening / closing means are provided for each of the communication passages, and the control means controls the opening / closing means in the compression stroke of each cylinder.

  According to the configuration of the invention, the operation of the invention according to claim 1 or 2 can be obtained for an internal combustion engine having a plurality of cylinders.

  According to the first aspect of the present invention, the pump loss can be reduced with a compact structure, and the apparatus can be labor-saving.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the pump loss can be efficiently reduced in accordance with the operating state of the internal combustion engine.

  According to the invention described in claim 3, the effect of the invention described in claim 1 or 2 can be obtained in an internal combustion engine having a plurality of cylinders.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which an in-cylinder pressure control device for an internal combustion engine according to the present invention is embodied will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of an engine system in this embodiment. A reciprocating engine 1 that is an internal combustion engine includes a plurality of cylinders 2 and a crankshaft 3. An intake passage 4 and an exhaust passage 5 are connected to the engine 1. The intake passage 4 includes a surge tank 6 and an air cleaner 7 located upstream thereof. In this embodiment, the throttle valve conventionally provided upstream of the surge tank 6 is eliminated. In the middle of the exhaust passage 5, two catalytic converters 8A and 8B arranged in series are provided.

  The engine 1 includes a cylinder block 11 and a cylinder head 12. Each cylinder 2 described above is provided in the cylinder block 11. Pistons 13 provided in each cylinder 2 are connected to the crankshaft 3 described above. In each cylinder 2, a combustion chamber 14 is formed between the piston 13 and the cylinder head 12. An intake port 15 and an exhaust port 16 communicating with each combustion chamber 14 are formed in the cylinder head 12. Each intake port 15 communicates with the intake passage 4. Each exhaust port 16 communicates with the exhaust passage 5. The intake valve 17 provided in each intake port 15 and the exhaust valve 18 provided in each exhaust port 16 are interlocked with the rotation of the crankshaft 3, that is, interlocked with the vertical movement of each piston 13. As a result, in conjunction with the four strokes of the engine 1, it is driven to open and close by a valve mechanism 20 including a camshaft 19 and the like. The injectors 21 provided in each cylinder 2 inject and supply fuel supplied from a fuel supply device (not shown) to the corresponding intake port 15. The fuel injected from each injector 21 and the air sucked into the intake passage 4 through the air cleaner 7 form a combustible mixture and are sucked into the combustion chambers 14.

  The spark plugs 22 provided in the respective combustion chambers 14 perform a spark operation upon receiving an ignition signal output from the ignition coil 23. Both parts 22 and 23 constitute an ignition device that ignites a combustible air-fuel mixture sucked into each combustion chamber 14. The combustible air-fuel mixture sucked into each combustion chamber 14 explodes and burns by the spark operation of each spark plug 22. The exhaust gas after combustion is discharged from each combustion chamber 14 to the outside through the exhaust port 16, the exhaust passage 5, and the catalytic converters 8A and 8B. As the combustible air-fuel mixture burns in each combustion chamber 14, each piston 13 moves up and down to rotate the crankshaft 3, whereby power is obtained in the engine 1.

  As shown in FIG. 1, a communication port 24 is formed in the cylinder block 11 corresponding to each of the combustion chambers 14 of each cylinder 2. Corresponding to each communication port 24, the cylinder block 11 is provided with an electromagnetic valve 25. A communication pipe 26 is connected between each solenoid valve 25 and the surge tank 6. That is, the electromagnetic valve 25 is provided for each of the cylinders 2, and the communication pipe 26 is provided for each of the electromagnetic valves 25. In this embodiment, the communication port 24 and the communication pipe 26 constitute a communication passage of the present invention in which one end communicates with each cylinder 2 and the other end communicates with the intake passage 4. Each electromagnetic valve 25 constitutes an opening / closing means of the present invention for opening / closing each communication path. The communication port 24, the electromagnetic valve 25, and the communication pipe 26 constitute a mechanical configuration of the in-cylinder pressure control device of the present invention.

  As shown in FIG. 1, various sensors 31, 32, 33, and 34 provided corresponding to the engine 1 constitute an operation state detection unit of the present invention for detecting the operation state of the engine 1. That is, the accelerator sensor 31 of the accelerator pedal module 27 provided in the driver's seat detects the depression angle of the accelerator pedal 27a as the accelerator opening ACCP, and outputs an electrical signal corresponding to the detected value. The water temperature sensor 32 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water flowing inside the cylinder block 11 and outputs an electrical signal corresponding to the detected value. A rotational speed sensor 33 provided in the engine 1 detects the rotational speed (engine rotational speed) NE of the crankshaft 3 and outputs an electrical signal corresponding to the detected value. The sensor 33 is configured to detect rotation of the shaft 3 at predetermined angles via a timing pulley 28 provided on the crankshaft 3. The sensor 33 corresponds to an operation stroke detection means of the present invention for detecting the operation stroke of the engine 1. The oxygen sensor 34 provided in the exhaust passage 5 detects the oxygen concentration (output voltage) Ox in the exhaust gas discharged to the exhaust passage 5 and outputs an electrical signal corresponding to the detected value. This sensor 34 is used to obtain the air-fuel ratio A / F of the combustible mixture supplied to each combustion chamber 14 of the engine 1.

  The engine system includes a control unit 40 that controls various controls. Various sensors 31 to 34 and each electromagnetic valve 25 are connected to the control unit 40. Further, each injector 21 and each ignition coil 23 are connected to the control unit 40.

  In this embodiment, the control unit 40 inputs signals output from the various sensors 31 to 34. The control unit 40 controls each injector 21, each ignition coil 23, each solenoid valve 25, and the like in order to execute fuel injection control, ignition timing control, in-cylinder pressure control, and the like based on these input signals. In this embodiment, the control unit 40 constitutes control means and opening / closing timing calculation means of the present invention.

  Here, the fuel injection control is to control the fuel injection amount and the injection timing by each injector 21 according to the operating state of the engine 1. The ignition timing control is to control the ignition timing by each ignition plug 22 by controlling each ignition coil 23 according to the operating state of the engine 1. In-cylinder pressure control means that when it is detected that each cylinder 2 is in the compression stroke, the detected pressure in the cylinder 2 (combustion chamber 14) is released to the surge tank 6 to thereby detect the cylinder 2 (combustion). It is to control by reducing the pressure in the chamber 14). Therefore, the control unit 40 controls each solenoid valve 25 when it is detected that each cylinder 2 is in the compression stroke.

  As is well known, the control unit 40 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like. The memory stores a predetermined control program related to various controls of the engine 1. The CPU executes the above-described various controls according to a predetermined control program based on detection signals from the various sensors 31 to 34 input via the input circuit.

  Next, processing contents of in-cylinder pressure control among various controls will be described. FIG. 2 is a flowchart showing the control program. The control unit 40 periodically executes the routine shown in FIG. 2 at predetermined intervals.

  First, in step 100, the control unit 40 determines whether or not the engine 1 has been started based on the engine rotational speed NE detected by the rotational speed sensor 33. If this determination is negative, the control unit 40 ends the process once as it is. If the above determination is affirmative, the control unit 40 reads the values of the accelerator opening ACCP, the cooling water temperature THW, the engine speed NE, and the oxygen concentration Ox detected by the sensors 31 to 34 in Step 110, respectively.

  Next, at step 120, the control unit 40 calculates an ignition timing for causing each spark plug 22 to perform a spark operation based on the read values of the accelerator opening ACCP, the coolant temperature THW, and the engine speed NE.

  In step 130, the control unit 40 calculates the air-fuel ratio of the engine 1 based on the read value of the oxygen concentration Ox.

  In step 140, the control unit 40 calculates an opening timing and a closing timing according to the operating state of the engine 1 for each electromagnetic valve 25 based on the calculated ignition timing and air-fuel ratio.

  In step 150, the control unit 40 calculates the current crank angle based on the detected value of the rotation speed sensor 33. The crank angle indicates a change in each stroke corresponding to the four strokes of the engine 1, that is, the intake stroke, the compression stroke, the explosion stroke, and the discharge stroke.

  In step 160, the control unit 40 determines whether it is the closing timing of the intake valve 17 in each cylinder 2 based on the calculated crank angle. When the intake valve 17 of each cylinder 2 is closed, it means that each cylinder 2 enters the compression stroke. If the determination result is negative, the control unit 40 ends the process as it is, assuming that each cylinder 2 is not in the compression stroke. If the determination result is affirmative, it is assumed that each cylinder 2 is in the compression stroke, and the control unit 40 opens the electromagnetic valve 25 of the corresponding cylinder 2 in step 170. That is, the solenoid valve 25 corresponding to the cylinder 2 that is in the compression stroke is driven to open.

  Next, in step 180, the control unit 40 determines whether or not it is the closing timing for the solenoid valve 25 of the corresponding cylinder 2. If this determination result is negative, the control unit 40 ends the process once as it is. When the determination result is affirmative, the control unit 40 drives the electromagnetic valve 25 of the corresponding cylinder 2 to be closed at step 190. That is, the solenoid valve 25 corresponding to the cylinder 2 that is in the compression stroke is driven to close. Then, the subsequent processing is temporarily terminated.

  In this embodiment, the in-cylinder pressure control device is configured by the control unit 40 that executes the in-cylinder pressure control as described above, the communication ports 24, the electromagnetic valves 25, the communication tubes 26, and the like.

  FIG. 3 is a time chart showing the relationship between ignition timing, intake valve 17 and exhaust valve 18 open periods, and opening / closing of the electromagnetic valve 25 with respect to the compression stroke in a certain cylinder 2. FIG. 4 is a graph showing the difference in the opening period of the electromagnetic valve 25 with respect to the opening and closing of the intake valve 17 during idling and partial load. As shown in FIGS. 3 and 4, when the crank angle reaches “a ° CA” after “180 ° CA”, the intake valve 17 is closed and the compression stroke starts. This “a ° CA” to “360 ° CA” is the compression stroke. Here, when “a ° CA” that is the closing timing of the intake valve 17 is detected when the engine 1 is idle, the electromagnetic valve 25 is opened from “a ° CA” to “c ° CA”. Further, when “a ° CA” that is the closing timing of the intake valve 17 is detected during partial load of the engine 1, the electromagnetic valve 25 is opened from “a ° CA” to “b ° CA”. The opening period (angle) of the solenoid valve 25 at the time of idling and partial load is larger at the time of idling than at the time of partial load. On the other hand, at the time of WOT of the engine 1 (at the time of full load), the electromagnetic valve 25 is not opened even if “a ° CA” that is the closing timing of the intake valve 17 is detected.

  According to the in-cylinder pressure control device of this embodiment described above, the control unit 40 is configured to adjust the engine rotational speed NE indicating the operation stroke of the engine 1 detected by the rotational speed sensor 33 when the engine 1 is idling or partially loaded. Based on the signal, it is determined whether or not each cylinder 2 of the engine 1 is in the compression stroke. When the control unit 40 determines that each cylinder 2 is in the compression stroke, the control unit 40 controls and opens the communication port 24 communicating with the cylinder 2 and the electromagnetic valve 25 provided in the communication pipe 26. Accordingly, the pressure in the combustion chamber 14 of the cylinder 2 in the compression stroke is released to the surge tank 6 in the intake passage 4 and the pressure in the combustion chamber 14 is reduced. The generated torque of the engine 1 required at this time is adjusted not by the intake amount introduced into the combustion chamber 14 during the intake stroke, but by the intake flow rate that flows out from the communication port 24 through the electromagnetic valve 25 and the communication tube 26 during the compression stroke. . For this reason, when the engine 1 having a plurality of cylinders 2 is idle or partially loaded, the torque generated by the engine 1 is adjusted without using a conventional throttle valve, so that pump loss can be reduced in each cylinder 2. it can. Thereby, the fuel consumption of the engine 1 can be improved.

  FIG. 5 shows a PV diagram when the engine 1 is partially loaded. In this diagram, the shaded area indicates the magnitude of the pump loss. As is clear from the comparison with the PV diagram of the conventional example in FIG. 7, it can be seen that the pump loss is smaller in this embodiment than in the conventional example even at the same partial load.

  Further, in the in-cylinder pressure control device of this embodiment, as the mechanical configuration, the communication ports 24, the communication pipes 26, and the electromagnetic valves 25 are provided as many as the number of each cylinder 2, so that the structure is relatively simple, compact, and lightweight. And the space occupied by these components can be made relatively small. Furthermore, in this in-cylinder pressure control apparatus, each electromagnetic valve 25 is only electrically controlled individually, so that a large driving force is not required, and labor saving as the apparatus can be achieved. As a result, when each solenoid valve 25 is operated, a large load is not applied to the power source, torque loss is not caused in the engine 1, and deterioration in fuel consumption of the engine 1 can be prevented.

  In this embodiment, the control unit 40 calculates the opening timing and the closing timing of each solenoid valve 25 based on the operation state (idle, partial load) detected by the various sensors 31-34. The control unit 40 controls each solenoid valve 25 based on the calculated opening timing and closing timing. Here, the pressure in each cylinder 2 (combustion chamber 14) in the compression stroke differs depending on the operating state of the engine 1 (during idling or partial load). Therefore, since the opening timing and closing timing of each solenoid valve 25 are controlled according to the operating state of the engine 1 (idle, partial load), the inside of each cylinder 2 (combustion chamber 14) according to the operating state. The pressure escapes to the surge tank 6 efficiently. For this reason, the pump loss of each cylinder 2 can be efficiently reduced according to the operating state of the engine 1.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of invention, it can also implement as follows.

  For example, in the above embodiment, a plurality of communication ports 24, a plurality of solenoid valves 25, and a plurality of communication pipes 26 are provided in accordance with the engine 1 having a plurality of cylinders 2. However, when the engine is a single cylinder. May be provided with one communication port, one electromagnetic valve, and one communication pipe.

The schematic block diagram which shows an engine system. The flowchart which shows a control program. Time chart showing the relationship between intake and exhaust valve opening periods and solenoid valve opening and closing. The graph which shows the difference in the open period of a solenoid valve with respect to opening and closing of an intake valve. PV diagram at the time of partial load. The PV diagram at the time of full load of a prior art example. The PV diagram at the time of partial loading of a prior art example.

Explanation of symbols

1 Engine 2 Cylinder 4 Intake passage 24 Communication port 25 Solenoid valve (opening / closing means)
26 communication pipe (24, 26: communication path)
31 Accelerator sensor 32 Water temperature sensor 33 Rotational speed sensor (operation stroke detection means)
34 Oxygen sensor (31-34: operating state detection means)
40 Control unit (control means, opening / closing timing calculation means)

Claims (3)

An in-cylinder pressure control device for controlling the pressure in a cylinder in an internal combustion engine connected to an intake passage,
A communication path having one end communicating with the cylinder and the other end communicating with the intake path;
Opening and closing means provided to open and close the communication path;
An operation stroke detecting means for detecting an operation stroke of the internal combustion engine;
An internal combustion engine comprising: control means for controlling the opening / closing means to reduce the pressure in the cylinder when it is determined that the cylinder is in the compression stroke based on the detected operation stroke; In-cylinder pressure control device. An operating state detecting means for detecting an operating state of the internal combustion engine;
An opening / closing timing calculating means for calculating an opening timing and a closing timing of the opening / closing means based on the detected operating state, and the control means controls the opening / closing means based on the calculated opening timing and closing timing. The in-cylinder pressure control device for an internal combustion engine according to claim 1, wherein the control is performed. The internal combustion engine has a plurality of cylinders;
The communication path is provided for each of the cylinders;
The opening / closing means is provided for each of the communication paths, and the control means controls the opening / closing means in a compression stroke of each cylinder. An in-cylinder pressure control device for an internal combustion engine according to claim 1.

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