JP2009121429A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover compressed air without giving a driver a sense of discomfort. <P>SOLUTION: This device includes a compressed air control device taking compressed air formed in a cylinder of an internal combustion engine during compression stroke under a predetermined operation condition to an outside, a compressed air storage tank recovering and storing the compressed air taken out by the compressed air control device, a compressed air storage tank inner pressure detection means detecting pressure in the compressed air storage tank, a cylinder pressure detection means detecting cylinder pressure of the internal combustion engine based on the operation condition, and a differential pressure control device controlling pressure difference between the cylinder pressure of the internal combustion engine and pressure in the compressed air storage tank. The compressed air control device is controlled to start recovery of compressed air to the compressed air storage tank after the differential pressure gets to a predetermined value or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine.

  There is known a system in which a tank for storing compressed air is installed in an internal combustion engine, and the compressed air is created and stored using energy or the like during vehicle deceleration.

  For example, in Patent Document 1, compressed air generated by an internal combustion engine during deceleration is collected in a tank, and when high torque is required for the engine, the compressed air is directly introduced (supercharged) into the combustion chamber. A technique aimed at increasing torque is disclosed. In this Patent Document 1, a variable valve mechanism that drives a third valve installed in a combustion chamber by a hydraulic actuator in addition to an intake valve and an exhaust valve is used as the means for realizing it.

Patent Document 2 discloses a technology that aims to improve fuel consumption by collecting compressed air generated by an internal combustion engine during traveling or decelerating into a tank and performing traveling while avoiding an operation region where engine efficiency is low. Has been. In this Patent Document 2, a variable valve mechanism that drives a gas flow control valve connected to an intake valve, an exhaust valve, and a pressure vessel by a hydraulic actuator is used as means for realizing the above.
Japanese Utility Model Publication No. 2-33283 Special table 2007-502389

  However, when creating and storing compressed air using an internal combustion engine, a drive torque for driving the internal combustion engine is required. Therefore, when the internal combustion engine is switched from a state in which compressed air is not created and stored to a state in which compressed air is created and stored, a large change occurs in the torque required to drive the internal combustion engine, which is transmitted to the vehicle. As a result, the driver may feel uncomfortable.

  Therefore, the present invention recovers the compressed air taken out by the compressed air take-out mechanism and the compressed air take-out mechanism that takes out the compressed air generated in the cylinder of the internal combustion engine in the compression stroke in a predetermined operation state. A compressed air storage tank for storing; a compressed air storage tank pressure detecting means for detecting a pressure in the compressed air storage tank; and an in-cylinder pressure detecting means for detecting an in-cylinder pressure of the internal combustion engine based on an operating state. And a differential pressure control means for controlling a pressure difference between the cylinder pressure of the internal combustion engine and the pressure in the compressed air storage tank, and the compressed air take-out mechanism has the pressure difference of a predetermined value or less. Control is performed so that the recovery of the compressed air to the compressed air storage tank is started from the time point.

  According to the present invention, at the start of recovery of compressed air to the compressed air storage tank, the pressure difference between the in-cylinder pressure and the pressure in the compressed air storage tank is controlled to be small. As a result, for example, there is no sudden movement of compressed air from the cylinder of the internal combustion engine into the compressed air storage tank, so that the pump loss does not increase and the occurrence of a significant decrease in torque is suppressed. Can do.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing an outline of an embodiment of the present invention, in which a compressed air storage tank for storing compressed air and a compressed air for extracting compressed air to the compressed air storage tank are stored in a normal engine. A compressed air control device as an air take-out mechanism and a differential pressure control device which is a differential pressure control means for controlling the pressure difference between the internal pressure of the compressed air storage tank and the pressure in the cylinder (combustion chamber) of the internal combustion engine are added. It has been configured.

  2 and 3 are system block diagrams of an embodiment of the present invention. FIG. 2 is a system block diagram showing an overall outline. FIG. 3 is a detailed diagram related to a compressed air control device and a differential pressure control device. It is a system block diagram. As shown in FIG. 2, engine rotation speed, vehicle speed, accelerator opening, throttle opening, intake air amount, tank pressure of the compressed air storage tank, crank angle, etc. are obtained from the corresponding sensor outputs, respectively, and ECM (engine control Module) and using these pieces of information to control the differential pressure and whether or not to extract compressed air.

  As shown in FIG. 3, the compressed air control signal that is the control command pressure of the compressed air control device is calculated by the air recovery condition calculation device using the crank angle, the engine rotation speed, the vehicle speed, and the accelerator opening.

  Further, a differential pressure control signal that is a control command value of the differential pressure control device is calculated by a differential pressure control amount calculation device using a cylinder internal pressure that is an in-cylinder pressure of the internal combustion engine and a tank pressure of the compressed air storage tank. . The cylinder internal pressure is calculated by the cylinder internal pressure calculation device using the intake pressure (intake negative pressure), the crank angle and the compression ratio at that time, or the intake valve closing timing. The intake pressure (intake negative pressure) is calculated by an intake pressure calculation device using the throttle opening and the engine speed.

  Note that the air recovery condition calculation device, intake pressure calculation device, cylinder internal pressure calculation device, and differential pressure control amount calculation device in FIG. 3 correspond to a series of calculation processes performed in the ECM, respectively. It is included.

  FIG. 4 is an explanatory diagram showing a schematic configuration of the engine 1 according to the first embodiment of the present invention. The engine 1 composed of a spark ignition gasoline engine has an intake valve 2 and an exhaust valve 3, and the intake air The valve mechanism on the valve 2 side is a direct acting type that drives the intake valve 2 by the intake cam 4a of the intake camshaft 4, and its valve lift characteristic is always constant. The valve mechanism on the exhaust valve 3 side is a direct acting type that drives the exhaust valve 3 by the exhaust cam 5a of the exhaust cam shaft 5, and its valve lift characteristic is always constant.

  In the cylinder 6, a piston 7 connected to a multi-link type piston-crank mechanism 31 described later is slidably disposed. A combustion chamber 8 is formed between the cylinder head fixed to the upper surface of the cylinder block and the piston 7.

  One end of a connection passage 9 is connected to the center of the ceiling surface of the combustion chamber 8. The connection passage 9 is connected to the compressed air storage tank 10 at the other end. Further, a compressed air flow rate control valve 13 is interposed in the connection passage 9. The internal pressure of the compressed air storage tank 10 is detected by a pressure sensor (not shown).

  A compression portion in which a valve lift characteristic is always constant is driven at a connection portion between the combustion chamber 8 and the connection passage 10 by a compressed air cam 12a of a compressed air camshaft 12 that rotates in synchronization with the rotation of the crankshaft. An air control valve 11 is arranged. The compressed air control valve 11 is capable of discharging compressed air generated in a cylinder 6 that is a cylinder of an internal combustion engine to a compressed air storage tank 10 in a compression stroke in a predetermined operation state.

  As shown in FIG. 5, the compressed air control valve 11 does not open normally, and when the condition for recovering the compressed air to the compressed air storage tank 10 is established in a predetermined operation state, The compressed air control valve 11 is controlled to open. When the compressed air control valve 11 opens, the compressed air flow control valve 13 is also controlled to open. Further, when the compressed air control valve 11 is closed, the compressed air flow rate control valve 13 is also controlled to close.

  Here, as a drive mechanism of the compressed air control valve 11, a valve opening / closing control is performed by an electromagnetic valve or an actuator driven by hydraulic pressure, a valve lift is changed to change the central angle of the valve lift, or a different cam. It is also possible to apply a so-called variable valve mechanism such as switching the use of a plurality of cams having profiles.

  Further, a fuel injection valve 14 is disposed so as to inject and supply fuel for each cylinder toward the intake port of each cylinder. A branch passage 15 is connected to each intake port, and upstream ends of the plurality of branch passages 15 are connected to a collector 16. An intake inlet passage 17 is connected to one end of the collector 16, and a throttle valve 18 is provided in the intake inlet passage 17. The throttle valve 18 includes an actuator (not shown) made of an electric motor, and its opening degree is controlled by a control signal given from the ECM. An air cleaner 19 is provided upstream of the throttle valve 18.

  The multi-link type piston-crank mechanism 31 will be described with reference to FIG.

  This multi-link type piston-crank mechanism 31 is connected to the piston 7 that slides in the cylinder 6 of the cylinder block 32 with one end connected via a piston pin 33, and to the other end of the upper link 34. A lower link 38 connected via a pin 35 and rotatably connected to a crank pin 37 of the crankshaft 36, and a connecting pin 39 further connected to the lower link 38 to limit the degree of freedom of the lower link 38. A control link 40 having one end connected to the internal combustion engine body and the other end swingably supported by the internal combustion engine main body. The swing support position of the control link 40 is an eccentric cam portion of the control shaft 41. 42 is variably controlled by 42.

  The control shaft 41 is disposed in parallel with the crankshaft 36 and is rotatably supported by the cylinder block 32. The control shaft 41 is driven in the rotational direction by an actuator 44 made of an electric motor via a gear mechanism 43, and its rotational position is controlled.

  In the multi-link type piston-crank mechanism 31 configured as described above, the swing support position at the lower end of the control link 40 changes depending on the rotational position of the control shaft 41, that is, the position of the eccentric cam portion 42, and the initial posture of the lower link 38 changes. Along with this, the top dead center position of the piston 7, and hence the compression ratio changes.

  In the above-described embodiment, the valve mechanism of the intake valve 2 and the valve mechanism of the exhaust valve 3 may change the center angle of the valve lift by changing the cam phase, or may have a plurality of different cam profiles. It is also possible to apply a so-called variable valve mechanism such as switching the use of a cam.

  More specifically, the variable valve mechanism 50 as shown in FIG. 7 can be applied to the valve mechanism of the intake valve 2 and the valve mechanism of the exhaust valve 3. For convenience of explanation, a case where the variable valve mechanism 50 shown in FIG. 7 is applied to the valve mechanism of the intake valve 2 will be described below.

  The variable valve mechanism 50 on the intake valve 2 side is known, for example, from Japanese Patent Application Laid-Open No. 2002-89341 and the like, and the variable lift / operating angle for continuously variably controlling the lift / operating angle of the intake valve 2. The mechanism 51 is combined with a phase variable mechanism 52 that continuously advances or retards the phase of the center angle of the lift (phase with respect to the crankshaft).

  Thus, according to the variable valve mechanism that combines the lift / operating angle variable mechanism 51 and the phase variable mechanism 52, both the intake valve opening timing and the intake valve closing timing can be arbitrarily controlled independently. At the same time, by reducing the lift amount (maximum lift amount) in the low load range, it is possible to limit the intake air amount according to the load. In a region where the lift amount is large to some extent, the amount of air flowing into the cylinder is mainly determined by the opening / closing timing of the intake valve 2, whereas in a state where the lift amount is sufficiently small, the air amount is mainly determined by the lift amount. .

  The outline of the lift / operating angle variable mechanism 51 will be described. The lift / operating angle variable mechanism 51 includes a hollow drive shaft 53 that is rotatably supported by the cylinder head and rotates in conjunction with the crankshaft. An eccentric cam 55 fixed to the drive shaft 53, a rotatable control shaft 56 disposed in parallel above the drive shaft 53, and a rocker arm swingably supported by an eccentric cam portion 57 of the control shaft 56 58 and a swing cam 60 that contacts the tappet 59 at the upper end of each intake valve 2. The eccentric cam 55 and the rocker arm 58 are linked by a link arm 61, and the rocker arm 58 and the swing cam 60 are linked by a link member 62. The link arm 61 has an annular portion 61 a rotatably fitted to the outer peripheral surface of the eccentric cam 55. Further, the extension portion 61 b of the link arm 61 is linked to one end portion of the rocker arm 58, and the upper end portion of the link member 62 is linked to the other end portion of the rocker arm 58. The eccentric cam portion 57 is eccentric from the axis of the control shaft 56, and accordingly, the rocking center of the rocker arm 58 changes according to the angular position of the control shaft 56.

  The swing cam 60 is rotatably supported by being fitted to the outer periphery of the drive shaft 53, and the lower end portion of the link member 62 is linked to the end portion extending to the side. On the lower surface of the swing cam 60, a base circle surface concentric with the drive shaft 53 and a cam surface extending in a predetermined curve from the base circle surface to the end are continuously provided. Is formed. The base circle surface is a section where the lift amount becomes zero, and when the swing cam 60 swings and the cam surface contacts the tappet 59, the lift is gradually lifted.

  The rotation position of the control shaft 56 is controlled by a lift / operating angle control actuator 65 formed of, for example, an electric motor provided at one end.

  For example, when the eccentric cam portion 57 is in the upper position by the actuator 65, the rocker arm 58 is positioned upward as a whole, and the end portion of the swing cam 60 is relatively lifted upward. That is, the initial position of the swing cam 60 is inclined in a direction in which the cam surface is separated from the tappet 59. Therefore, when the swing cam 60 swings with the rotation of the drive shaft 53, the base circle surface continues to contact the tappet 59 for a long time, and the period during which the cam surface contacts the tappet 59 is short. Therefore, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.

  On the other hand, if the eccentric cam portion 57 is positioned downward, the rocker arm 58 is positioned downward as a whole, and the end portion of the swing cam 60 is relatively pushed down. That is, the initial position of the swing cam 60 is inclined in a direction in which the cam surface approaches the tappet 59. Therefore, when the swing cam 60 swings with the rotation of the drive shaft 53, a large lift amount is obtained and the operating angle is also expanded.

  Since the initial position of the eccentric cam portion 57 can be continuously changed, the valve lift characteristic changes continuously as shown in FIG. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously.

  Next, the phase variable mechanism 52 includes a sprocket 71 provided at the front end portion of the drive shaft 53, and a phase control hydraulic actuator 72 that relatively rotates the sprocket 71 and the drive shaft 53 within a predetermined angle range. And is composed of. The sprocket 71 is linked to the crankshaft via a timing chain or timing belt (not shown). Accordingly, the hydraulic control to the phase control hydraulic actuator 72 causes the sprocket 71 and the drive shaft 53 to rotate relative to each other, thereby delaying the lift center angle. That is, the lift characteristic curve itself does not change, and the whole advances or retards.

  FIG. 9 is a timing chart showing a problem when recovering compressed air. Assume a case where the driver takes his foot off the accelerator at time A and shifts from a traveling state at a constant vehicle speed to a deceleration state. The throttle valve 18 is closed and the vehicle starts to decelerate. After a predetermined time, when the fuel supply to the engine 1 is stopped at time B and the fuel cut state is entered, an instruction is given to open the compressed air control valve 11. That is, during the period from time B to time C, the open flag of the compressed air control valve flag is established, and the compressed air control valve 11 is controlled to open (open) in the compression stroke. When the compressed air control valve 11 is opened, the compressed air is stored in the compressed air storage tank 10. As a result, as shown in FIG. 10, the engine torque is smaller than the torque in the fuel cut state by the pump loss. That is, as shown in FIG. 11, the negative torque when there is compressed air increase by the amount of pump loss in the expansion stroke, compared to the negative torque when there is no compressed air recovery.

  At the time of deceleration, the torque converter lock-up clutch is engaged, so that a change in torque directly leads to a change in deceleration of the vehicle. Therefore, the engine torque change at this time is felt as a shock to the driver, and the driver may feel uncomfortable.

  Therefore, in the present embodiment, for example, the compression ratio is changed according to the pressure in the compressed air storage tank 10, and the cylinder pressure (in-cylinder pressure) and the compressed air storage tank 10 are changed at time B when the recovery of the compressed air starts. Control is performed so that the pressure difference from the internal pressure becomes substantially zero. FIG. 12 is a timing chart when the compressed air is recovered when the pressure in the cylinder when the compressed air control valve 11 is opened is equal to or lower than the pressure in the compressed air storage tank 10.

  As a result, when the compressed air control valve flag is switched from the closed flag to the opened flag, a sudden movement of the compressed air to the compressed air storage tank 10 does not occur, so that the pump loss does not increase and a significant decrease in torque occurs. Is suppressed.

  However, in this state, there is no pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10, and the compressed air cannot be recovered. Therefore, in order to reduce the pump loss in the intake stroke while generating a pressure difference (differential pressure) and aim to recover the compressed air without significantly changing the engine torque, as shown in FIG. The throttle valve 18 is gradually opened from the timing, the suction negative pressure is reduced, the pump loss is reduced, the air sucked into the cylinder 6 is increased, the cylinder pressure is increased, and the cylinder pressure and compression are increased. The pressure difference from the pressure in the air storage tank 10 is increased.

  As a result, the compressed air can be recovered while the driving torque as the engine remains substantially the same. That is, as shown in FIG. 13, the negative torque when there is no recovery of compressed air and the negative torque when there is recovery of compressed air can be made substantially the same.

  Further, when the recovery of the compressed air is terminated, after the post-processing for returning the throttle opening that has been enlarged during the recovery of the compressed air is completed, the compressed air control valve flag is switched from the open flag to the closed flag. .

  FIG. 14 is a characteristic diagram of various parameters used in this embodiment. The compression ratio at the start of the recovery of the compressed air is set high according to the tank pressure of the compressed air storage tank 10 in order to reduce the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 (FIG. 14a). . The negative suction pressure during the recovery of the compressed air is set so as to decrease in accordance with the recovery amount to the compressed air storage tank 10 (FIG. 14b).

  FIG. 15 is a flowchart showing the flow of control in this embodiment described above.

  In S101, the accelerator opening, the engine speed, and the vehicle speed are read.

  In S102, it is determined whether the fuel supply of the engine can be stopped using the accelerator opening, the engine speed, and the vehicle speed (whether the fuel can be cut). If the fuel can be cut, the process proceeds to S103, and if not, the process proceeds to S106. . As an example of the fuel cut condition in S102, the accelerator opening is a predetermined value (ex. 0.5 deg) or less, the engine speed is a predetermined value (ex. 1000 rpm) or more, and the vehicle speed is a predetermined value (ex. 15 km / h). In the above case, it is determined that fuel cut is possible.

  In S103, when a predetermined cycle (ex. 2 cycles) or a predetermined time (ex. 100 ms) has elapsed to wait for the internal residual gas to be discharged after the fuel cut condition is satisfied, When the pressure difference between the pressure and the pressure in the compressed air storage tank 10 is substantially zero, it is determined that the compressed air recovery condition is satisfied, and the process proceeds to S104, and the compressed air recovery condition is not satisfied. The process proceeds to S105.

  Here, the recovery condition of the compressed air is set so that the fuel cut condition is not satisfied before or at the same time, and after the recovery condition is satisfied, for example, the accelerator opening is a predetermined value (ex. 0). It is not established when at least one of the engine speed is equal to or higher than a predetermined value (ex.1200 rpm) and the vehicle speed is equal to or higher than a predetermined value (ex.20 km / h).

  In S104, the throttle opening is adjusted so that the sum of the pump loss due to the suction negative pressure and the pump loss due to air recovery is substantially equal, while the compressed air control valve 11 is opened during the compression stroke, and the compressed air is stored in the compressed air storage tank. 10 (see FIG. 16 described later).

  In S105, it is determined whether or not the post-processing for returning the throttle opening increased to increase the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 has been completed, and has been completed. In step S104, the post-processing flag is turned OFF and the process proceeds to S104. If not completed, the post-processing flag is turned ON and the process proceeds to S106.

  In S106, the compressed air control valve flag is switched from the open flag to the closed flag, and the recovery of the compressed air in the compression stroke ends.

  Here, in this embodiment, when the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 is made substantially zero, the pressure in the cylinder is estimated as follows. In the present embodiment, the pressure in the compressed air storage tank 10 is directly detected by a pressure sensor (not shown) as described above.

  Hereinafter, a method for estimating the cylinder pressure will be described.

  First, the intake pressure Pm is estimated from the engine speed and the throttle opening (see FIG. 14b).

  Next, the cylinder internal volume Vc at the timing (IVC) when the intake valve 2 is closed is calculated. Specifically, the piston position is obtained from the crank angle, and is calculated using the piston bore area and the combustion chamber volume. For simplicity, the relationship with the crank angle may be set in the table in advance.

  Then, the cylinder internal volume Vo at the timing when the compressed air control valve 11 is opened is calculated. Specifically, the piston position is obtained from the crank angle, and is calculated using the piston bore area and the combustion chamber volume. For simplicity, the relationship with the crank angle may be set in the table in advance (see FIG. 14c).

Finally, the cylinder pressure Pc is estimated using the above result. Specifically, it is calculated from the following equation (1), assuming adiabatic compression of air.
[Equation 1]
Pc = Pm × (Vc / Vo) ^k (1)
In the above formula (1), k is the specific heat ratio of air, and k = 1.4.

  Next, a specific control method for making the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 described above in S103 and the like substantially zero will be described in detail.

  As an example, the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 can be controlled to be substantially zero by adjusting the throttle opening and adjusting the pressure in the branch passage 15.

  When the variable valve mechanism 50 as described above is applied, by adjusting the IVC (intake valve closing timing) using the variable valve mechanism 50, the cylinder pressure and the compressed air storage tank are adjusted. It is also possible to control the pressure difference with the pressure within 10 to be substantially zero. More specifically, if the cylinder pressure> compressed air storage tank pressure, IVC (intake valve closing timing) is set to the TDC (top dead center) side. If the cylinder pressure ≦ compressed air storage tank pressure, By controlling IVC (intake valve closing timing) to the BDC (bottom dead center) side, the pressure difference can be controlled to substantially zero.

  Further, the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 can be controlled to be substantially zero by adjusting the combustion chamber volume using the multi-link type piston-crank mechanism 31. More specifically, if the cylinder pressure> compressed air storage tank pressure, the combustion chamber volume is increased (low compression ratio side). If the cylinder pressure ≦ compressed air storage tank pressure, the combustion chamber volume is increased. By making it small (high compression ratio side), it is possible to control the pressure difference to substantially zero.

  Further, the flow rate is controlled by adjusting the opening degree of the compressed air flow rate control valve 13, and the pressure difference between the pressure in the cylinder and the pressure in the compressed air storage tank 10 is substantially equal to the case where the pressure difference is substantially zero (compression from the cylinder 6). It is also possible to make a small flow rate of air moving to the air storage tank 10). In this case, when the compressed air control valve 11 is opened, the pressure between the compressed air flow control valve 13 and the compressed air control valve 11 is adjusted so that the compressed air flow control valve 13 is opened. The pressure rises faster than the pressure in the tank 10.

  FIG. 16 is a flowchart showing the control flow of the process during recovery of compressed air in the above-described embodiment, and is a flowchart showing the control flow in S104 of FIG. 15 described above. FIG. 17 shows a PV diagram during the recovery of compressed air in the above-described embodiment.

  In S201, the pressure in the compressed air storage tank 10 is read and the cylinder pressure is calculated.

  In S202, the pump loss of the intake stroke is obtained from the intake negative pressure obtained from the throttle opening and the engine speed.

  Further, the pressure in the cylinder when the compressed air control valve 11 is closed is obtained from the pressure in the cylinder when the compressed air control valve 11 is opened and the pressure in the compressed air storage tank 10 to obtain the pump loss of the expansion stroke. As an example, a pressure drop allowance during recovery of compressed air is obtained from the relationship between the pressure when the compressed air control valve 11 is opened and the tank pressure of the compressed air storage tank 10 (see FIG. 18), and the obtained pressure drop allowance is obtained. Ask more.

  In S203, it is determined whether or not the above-described post-processing flag is ON. If the post-processing flag is ON, the process proceeds to S206, and if not, the process proceeds to S204.

  In S204, it is determined whether or not the throttle opening is smaller than a predetermined value. If the throttle opening is smaller than the predetermined value, the process proceeds to S205, and if not, the process proceeds to S207.

  In S205, the pump loss in the intake stroke in which the throttle opening is gradually opened is reduced.

  In S206, the throttle opening is gradually closed to restore the throttle opening enlarged in S204 and S205.

  At this time, in order to make the negative torque of the engine substantially constant, it is desired to make the intake stroke pump loss when the throttle is fully closed and the intake stroke pump loss + compression stroke pump loss substantially the same.

  Therefore, in S207 to S209, the compression ratio is adjusted according to the difference between the intake stroke pump loss when the throttle valve is fully closed and the intake stroke pump loss + compression stroke pump loss, so that both become substantially constant.

  In S208, if the compression ratio is increased, the pressure in the cylinder is increased when the recovery valve is opened, so that the pressure drop is increased. Further, when the compression ratio is lowered in S209, the pressure in the cylinder is reduced when the recovery valve is opened, so the pressure drop is reduced.

  In the present embodiment described above, when the recovery of compressed air to the compressed air storage tank 10 is started, the pressure difference between the in-cylinder pressure (in-cylinder pressure) and the pressure in the compressed air storage tank 10 is controlled to be small. Is done. As a result, for example, there is no sudden movement of the compressed air from the cylinder of the internal combustion engine into the compressed air storage tank 10, so that the pump loss does not increase and the occurrence of a significant decrease in torque is suppressed. be able to.

  Hereinafter, although other embodiment of this invention is described, about the component same as 1st Embodiment mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  FIG. 19 is an explanatory diagram showing a schematic configuration of the engine 21 in the second embodiment of the present invention. The engine 21 in the second embodiment has substantially the same configuration as the engine 1 in the first embodiment described above, but the connection passage 9 is connected to the exhaust passage 22 and the connection between the exhaust passage 22 and the connection passage 9 is made. An exhaust control valve 23 is disposed in the exhaust passage 22 on the exhaust downstream side of the position.

  The exhaust control valve 23 is driven to open and close in the exhaust passage 22 by an actuator (not shown). When the valve is closed, the flow of exhaust to the downstream side of the exhaust control valve 23 is restricted.

  In the second embodiment, the variable valve mechanism 50 described above is applied as the drive mechanism of the exhaust valve 3.

  Even in the second embodiment, as in the first embodiment described above, the compressed air is compressed when the predetermined operation state is established and the condition for recovering the compressed air to the compressed air storage tank 10 is satisfied. It collects in the air storage tank 10.

  That is, in the second embodiment, as shown in FIG. 20, when a condition for recovering the compressed air to the compressed air storage tank 10 is established in a predetermined operation state, the exhaust control valve 23 is set in the compression stroke. Control is performed to close the valve, and the compressed air flow rate control valve 13 is controlled to open. The exhaust control valve 23 is normally open, and the compressed air flow control valve 13 is normally closed.

  In such a second embodiment, the same operational effects as those of the first embodiment described above can be obtained.

  Each of the above embodiments is an application example to a so-called port-injection gasoline engine. However, it can also be applied to a direct-injection gasoline engine in which fuel is directly injected into a cylinder.

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

  (1) A control device for an internal combustion engine includes a compressed air extraction mechanism that extracts compressed air generated in a cylinder of the internal combustion engine in a compression stroke in a predetermined operation state, and a compression that is extracted by the compressed air extraction mechanism. Compressed air storage tank for collecting and storing air, compressed air storage tank pressure detecting means for detecting the pressure in the compressed air storage tank, and in-cylinder for detecting the in-cylinder pressure of the internal combustion engine based on the operating state Pressure detecting means; and differential pressure control means for controlling the pressure difference between the in-cylinder pressure of the internal combustion engine and the pressure in the compressed air storage tank, and the compressed air take-out mechanism has the pressure difference of a predetermined value. Control is performed so that the recovery of the compressed air to the compressed air storage tank is started from the time point when it becomes below. Thus, at the start of recovery of compressed air to the compressed air storage tank, the pressure difference between the in-cylinder pressure and the pressure in the compressed air storage tank is controlled to be small. As a result, for example, there is no sudden movement of compressed air from the cylinder of the internal combustion engine into the compressed air storage tank, so that the pump loss does not increase and the occurrence of a significant decrease in torque is suppressed. Can do.

  (2) In the control apparatus for an internal combustion engine according to (1), the differential pressure control means controls the pressure difference to be substantially constant when the compressed air is collected in the compressed air storage tank. Has been. As a result, during the recovery of the compressed air to the compressed air storage tank, the driving torque as the engine becomes substantially constant, and the driver does not feel uncomfortable.

  (3) In the control apparatus for an internal combustion engine according to (1), when the differential pressure control means collects the compressed air in the compressed air storage tank, the pressure difference is transferred to the compressed air storage tank. It is controlled so as to increase in accordance with the time from the start of recovery of compressed air. As a result, more compressed air can be recovered in the compressed air storage tank without causing the driver to feel uncomfortable.

  (4) The control device for an internal combustion engine according to (1) includes pump loss detection means for detecting a pump loss of the internal combustion engine based on an operating state of the internal combustion engine, and the differential pressure control means includes the compressed air. When the compressed air is recovered in the storage tank, the sum of the pump loss in the intake stroke due to the negative pressure and the expansion stroke due to the recovery of the compressed air to the compressed air storage tank becomes substantially constant. So that it is controlled. As a result, the sum of the pump loss in the intake stroke and the pump loss in the expansion stroke is controlled to be substantially constant, so that the minus driving force is substantially constant, and the amount of compressed air recovered is increased without causing the driver to feel uncomfortable. Can do.

  (5) In the control device for an internal combustion engine according to any one of (1) to (4), the compressed air extraction mechanism is configured to open an exhaust valve only during a predetermined period of the compression stroke. Open / close means, a connection passage connecting the compressed intake storage tank and the exhaust passage, an exhaust control valve disposed in the exhaust passage downstream of the connection position of the exhaust passage and the connection passage, And an exhaust control valve opening / closing means for closing the exhaust control valve only during a predetermined period during the compression stroke, and when the exhaust valve opens during the compression stroke, the exhaust passage is closed by closing the exhaust control valve. And the compressed air is collected in the compressed intake storage tank through the connection passage. Thus, the compressed air take-out mechanism can be realized mainly by modifying the exhaust system of a conventional general internal combustion engine, which is advantageous in terms of cost.

  (6) In the control device for an internal combustion engine according to any one of (1) to (4), the compressed air extraction mechanism includes a connection passage that connects a combustion chamber of the internal combustion engine and the compressed air storage tank; A compressed air control valve disposed at a connection portion between the connection passage and the combustion chamber; and a compressed air control valve opening / closing means for opening the compressed air control valve only for a predetermined period during a compression stroke. When the compressed air control valve opens during the compression stroke, the compressed air is recovered to the compressed intake storage tank via the connection passage. Thereby, since the compressed air can be directly recovered from the cylinder, the recovery efficiency of the compressed air can be improved.

  (7) In the control device for an internal combustion engine according to any one of (1) to (6), the differential pressure control means adjusts an amount of air that is disposed in an intake passage and is sucked into a cylinder of the internal combustion engine. The in-cylinder pressure is changed by changing the valve opening of the throttle valve, and the pressure difference is controlled. As a result, the differential pressure control means is configured from the existing configuration without adding a new mechanism or the like, which is advantageous in terms of cost.

  (8) In the control device for an internal combustion engine according to any one of (1) to (6), the differential pressure control means includes an intake valve closing timing changing means capable of changing an intake valve closing timing, The pressure difference is controlled by changing the intake valve closing timing. When the intake valve closing timing is changed, the effective compression ratio of the internal combustion engine changes. That is, the pressure difference between the in-cylinder pressure of the internal combustion engine and the pressure of the compressed air stored in the compressed air storage tank is controlled by changing the effective compression ratio of the internal combustion engine. As a result, it is possible to cope with modification of only the head, which is advantageous in terms of cost.

  (9) In the control device for an internal combustion engine according to any one of (1) to (6), the differential pressure control means includes a piston top dead center position variable means capable of changing a top dead center position of the piston. The pressure difference is controlled by changing the piston top dead center position.

  When the intake valve closing timing is changed, the effective compression ratio of the internal combustion engine changes. That is, the pressure difference between the in-cylinder pressure of the internal combustion engine and the pressure of the compressed air stored in the compressed air storage tank is controlled by changing the effective compression ratio of the internal combustion engine. As a result, since the total intake air amount can be controlled, a large amount of compressed air can be recovered.

  (10) In the control device for an internal combustion engine according to any one of (1) to (6), the differential pressure control means includes a piston top dead center position variable means capable of changing a top dead center position of the piston, Intake valve closing timing changing means capable of changing the closing timing of the intake valve, and the pressure difference is controlled by changing the piston top dead center position and the intake valve closing timing. Thereby, the control range of the compression ratio can be widened.

  (11) The control device for an internal combustion engine according to any one of (1) to (6) is connected to the compressed air storage tank, and the compressed air generated in the cylinder of the internal combustion engine in the compressed air storage tank The differential pressure control means has a flow control valve that is interposed in the connection passage and can control the opening and closing of the connection passage, and controls the valve opening degree of the flow control valve. To control the pressure difference. As a result, the pressure difference can be easily adjusted.

The explanatory view showing the outline of one embodiment of the present invention typically. 1 is a system block diagram showing an overall outline of an embodiment of the present invention. The detailed system block diagram regarding the compressed air control apparatus and differential pressure control apparatus of one Embodiment of this invention. Explanatory drawing which shows schematic structure of the engine in 1st Embodiment of this invention. Explanatory drawing which showed typically the valve timing of the intake valve, exhaust valve, and compressed air control valve in 1st Embodiment of this invention. Explanatory drawing which shows schematic structure of a multi-link type piston-crank mechanism. Explanatory drawing which shows the principal part of the variable valve mechanism applicable to this invention. The characteristic view which shows the characteristic change of a lift and an operating angle by a variable valve mechanism. The timing chart which shows the subject at the time of collect | recovering compressed air. It is a PV diagram when the problem at the time of collect | recovering compressed air is not solved, (a) is a PV diagram when not recovering compressed air, (b) is a case where recovering compressed air P-V diagram. Explanatory drawing which showed typically the generation | occurrence | production state of the minus torque of an engine when the subject at the time of collect | recovering compressed air is not solved. Timing chart at the time of compressed air recovery in the present invention Explanatory drawing which showed typically the generation | occurrence | production situation of the negative torque of the engine in this invention. It is a characteristic view of various parameters, (a) is a characteristic view showing the correlation between the compression ratio and the compressed air storage tank pressure, (b) is a characteristic view showing the correlation between the throttle opening, the engine speed and the intake pressure. (C) is a characteristic view which shows the correlation of a cylinder internal volume and a crank angle. The flowchart which shows the flow of control in 1st Embodiment of this invention. The flowchart which shows the flow of control of the process during collection | recovery of compressed air. The PV diagram during collection | recovery of the compressed air in 1st Embodiment of this invention. The characteristic view which shows the correlation between the pressure at the time of a compressed air control valve opening, the tank pressure of a compressed air storage tank, and the pressure drop allowance during compressed air collection | recovery. Explanatory drawing which shows schematic structure of the engine in 2nd Embodiment of this invention. Explanatory drawing which showed typically the valve timing of the intake valve in the 2nd Embodiment of this invention, an exhaust valve, an exhaust control valve, and a compressed air flow control valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake valve 3 ... Exhaust valve 9 ... Connection passage 10 ... Compressed air storage tank 11 ... Compressed air control valve 23 ... Exhaust control valve

Claims (11)

A compressed air take-out mechanism for taking out the compressed air generated in the cylinder of the internal combustion engine in the compression stroke in a predetermined operation state;
A compressed air storage tank for collecting and storing the compressed air taken out by the compressed air take-out mechanism;
A pressure detection means in the compressed air storage tank for detecting the pressure in the compressed air storage tank;
In-cylinder pressure detecting means for detecting the in-cylinder pressure of the internal combustion engine based on the operating state;
Differential pressure control means for controlling the pressure difference between the cylinder pressure of the internal combustion engine and the pressure in the compressed air storage tank,
The control apparatus for an internal combustion engine, wherein the compressed air take-out mechanism is controlled so that recovery of the compressed air to the compressed air storage tank is started from the time when the pressure difference becomes a predetermined value or less.   2. The internal combustion engine according to claim 1, wherein the differential pressure control means is controlled so that the pressure difference becomes substantially constant when the compressed air is recovered in the compressed air storage tank. Control device.   The differential pressure control means is controlled so that, when the compressed air is recovered in the compressed air storage tank, the pressure difference becomes larger according to the time from the start of the recovery of the compressed air to the compressed air storage tank. The control apparatus for an internal combustion engine according to claim 1, wherein Based on the operating state of the internal combustion engine, having a pump loss detection means for detecting the pump loss of the internal combustion engine,
The differential pressure control means, when recovering compressed air to the compressed air storage tank, the pressure difference causes an intake stroke pump loss due to suction negative pressure and an expansion stroke due to the compressed air recovery to the compressed air storage tank. 2. The control device for an internal combustion engine according to claim 1, wherein the sum of the pump loss and the pump loss is controlled to be substantially constant. The compressed air take-out mechanism includes an exhaust valve compression stroke opening / closing means that opens the exhaust valve only during a predetermined period of the compression stroke, a connection passage connecting the compressed intake storage tank and the exhaust passage, the exhaust passage, and the exhaust passage. An exhaust control valve disposed in the exhaust passage downstream of the connection position with respect to the connection passage, and an exhaust control valve opening / closing means for closing the exhaust control valve only for a predetermined period during the compression stroke. Have
When the exhaust valve is opened during the compression stroke, the exhaust passage is closed by closing the exhaust control valve, and the compressed air is recovered to the compressed intake storage tank through the connection passage. The control device for an internal combustion engine according to any one of claims 1 to 4. The compressed air take-out mechanism includes a connection passage that connects a combustion chamber of the internal combustion engine and the compressed air storage tank, a compressed air control valve that is disposed at a connection portion between the connection passage and the combustion chamber, and the compressed air. Compressed air control valve opening and closing means for opening the control valve only during a predetermined period during the compression stroke,
The control of the internal combustion engine according to any one of claims 1 to 4, wherein when the compressed air control valve is opened during a compression stroke, the compressed air is recovered to the compressed intake air storage tank through the connection passage. apparatus.   The differential pressure control means has a throttle valve that is disposed in the intake passage and adjusts the amount of air taken into the cylinder of the internal combustion engine, and changes the in-cylinder pressure by changing the valve opening degree of the throttle valve. The control device for an internal combustion engine according to any one of claims 1 to 6, wherein the pressure difference is controlled.   The differential pressure control means includes an intake valve closing timing changing means capable of changing an intake valve closing timing, and the pressure difference is controlled by changing the intake valve closing timing. The control apparatus of the internal combustion engine in any one of 1-6.   The differential pressure control means has piston top dead center position variable means capable of changing the top dead center position of the piston, and controls the pressure difference by changing the piston top dead center position. The control device for an internal combustion engine according to any one of claims 1 to 6.   The differential pressure control means has a piston top dead center position variable means capable of changing the piston top dead center position, and an intake valve closing timing change means capable of changing the closing timing of the intake valve. The control apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the pressure difference is controlled by changing a position and an intake valve closing timing. Connected to the compressed air storage tank, and having a connecting passage for guiding the compressed air generated in the cylinder of the internal combustion engine to the compressed air storage tank;
The differential pressure control means includes a flow rate control valve that is interposed in the connection passage and can control the opening and closing of the connection passage, and controls the pressure difference by controlling the valve opening degree of the flow rate control valve. The control device for an internal combustion engine according to claim 1, wherein the control device is an internal combustion engine.

Images