JP4877209B2 - Control device for internal combustion engine - Google Patents

Description

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

If the engine is driven using compressed air, fuel consumption can be suppressed, and deterioration of exhaust performance can also be suppressed. For example, Patent Document 1 aims to realize the above by collecting compressed air to a tank during traveling or decelerating and performing traveling using compressed air in an operation region where engine efficiency is reduced. As a means for realizing this, a variable valve mechanism is used in which an intake valve, an exhaust valve, and a compressed air flow control valve are driven by a hydraulic actuator.
Special table 2007-502389

  However, in view of the high cost of the variable valve mechanism and insufficient reliability, it is important to realize it with a conventional fixed cam. Since the conventional fixed cam cannot arbitrarily control the valve opening / closing, the intake air amount must be controlled by the throttle when switching from the compressed air drive to the engine drive by combustion. In that case, there will be a delay in the development of negative pressure and sudden deceleration will occur due to lack of combustion torque or misfire at the time of switching, or sudden acceleration or shock will occur due to a sudden increase in combustion torque by increasing the fuel injection amount in consideration of the delay. There was a problem of drivability. Also. In order to solve these problems, if the intake air amount is controlled from the compressed air drive mode, the pumping loss increases accordingly, and the efficiency during the compressed air drive mode is reduced.

  Even when the intake air amount is controlled using a variable valve mechanism that can change the valve lift amount and opening / closing timing of the intake valve, instead of the conventional fixed cam and throttle configuration, the response of the variable valve mechanism There was a possibility that the intake air amount could not be controlled due to the delay, and there was the same problem as above.

  Therefore, the control device for an internal combustion engine according to the present invention includes a control valve for controlling the inflow of air into the cylinder other than the intake and exhaust valves, a tank for storing compressed air communicating with the control valve, and the tank A tank internal state measuring means for measuring the internal state, a target intake air amount determining means for determining the amount of air to be sucked into the cylinder through the intake valve, and an intake air amount control means for controlling the intake air amount, Mode switching means for switching between a combustion drive mode driven by combustion and a compressed air drive mode driven by flowing compressed air from the control valve into the cylinder according to operating conditions; and from the control valve during the compressed air drive mode Target inflow air amount determining means for determining the amount of air flowing into the cylinder, and inflow air amount for controlling the amount of air flowing into the cylinder by opening and closing the control valve at least in the expansion stroke And control means, is characterized by and a control amount change determining means for performing control amount change of the intake air amount control means in said air-driven mode in.

  According to the present invention, since the control amount change condition of the intake air amount is changed according to the operating condition, the intake air according to the required engine load is switched even if the engine travel is switched from the compressed air drive mode to the combustion drive mode. Therefore, excessive engine torque and misfire can be suppressed, and an increase in pump loss during the compressed air drive mode before switching can be suppressed.

  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 a normal vehicle engine, a compressed air storage tank for storing compressed air, and a compressed air into a cylinder. A control valve (corresponding to a compressed air control valve described later) for controlling inflow is added. The compressed air storage tank is a constant volume tank that stores at a constant capacity or a constant pressure tank that stores at a constant pressure. The control valve controls the inflow of air into the cylinder other than the intake valve.

  The control valve and the ECM (engine control module) for controlling the engine have engine rotation speed, vehicle speed, accelerator opening, throttle opening, intake air amount, compressed air storage tank pressure, crank angle, etc., respectively. The input is obtained from the corresponding sensor output. Sensor signals from these various sensors are input to operating condition detection means in the ECU. The ECM controls the control valve and the engine using information from these various sensors.

  The ECM has mode switching means, control amount change determination means, target intake air amount determination means, target inflow air amount determination means, intake air amount control means, and inflow air amount control means.

  The mode switching means operates between a combustion drive mode driven by combustion and a compressed air drive mode driven by flowing compressed air from the control valve into the cylinder (for example, engine speed and intake air amount as engine load). And the pressure of the compressed air storage tank). The control amount change determining means changes the control amount based on operating conditions (for example, engine speed, intake air amount as engine load and tank pressure of the compressed air storage tank) and a control signal (drive mode signal) from the mode switching means. A signal is output to the target intake air amount determining means and the target inflow air amount determining means. The target intake air amount determination means calculates the target intake air amount based on the operating conditions (for example, the accelerator opening and the engine speed) and the control amount change signal. The target inflow air amount determining means calculates the target inflow air amount based on the operating conditions (for example, the engine speed and the intake air amount as the engine load) and the control amount change signal. The intake air amount control means controls the throttle opening so that the target intake air amount calculated by the target intake air amount determination means is supplied into the cylinder. The inflow air amount control means controls the opening / closing timing of the control valve so that the target inflow air amount calculated by the target inflow air amount determination means is supplied into the cylinder.

  Further, as shown in FIG. 2, the control amount change determining means includes a compressed air drive remaining time calculating means for calculating a remaining time (compressed air drive remaining time) that can be driven in the compressed air drive mode during the compressed air drive mode; A target air amount arrival time calculating means for calculating a time required to reach a target intake air amount corresponding to an engine load in the combustion drive mode during the compressed air drive mode (target air amount arrival time); and a remaining compressed air drive time And a control amount change execution determining means for outputting a control amount change signal based on the target air amount arrival time.

  FIG. 3 is an explanatory diagram showing a schematic configuration of the engine 1 according to the first embodiment of the present invention. The engine 1 including 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.

  A piston 7 is slidably disposed in the cylinder 6. 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 compressed air control valve 11 that is driven to open and close by an actuator 12 is disposed at a connection portion between the combustion chamber 8 and the connection passage 10. The drive system of the actuator 12 may be hydraulic or electromagnetic.

  The compressed air control valve 11 discharges compressed air generated in the cylinder 6 which is the cylinder of the internal combustion engine to the compressed air storage tank 10 during the compression stroke in a predetermined operation state, and expands during the compressed air drive mode. In the stroke, the compressed air in the compressed air storage tank 10 can be discharged into the cylinder. 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 driving mechanism of the compressed air control valve 11, a so-called acceptable mechanism such as changing the cam phase to change the central angle of the valve lift, or switching the use of a plurality of cams having different cam profiles is used. It is also possible to apply a variable valve mechanism.

  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. The present invention can also be applied to a direct injection gasoline engine that directly injects fuel into a 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.

  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. 4 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, the case where the variable valve mechanism 50 shown in FIG. 4 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. 6 is an explanatory diagram showing an outline of a method of driving the engine 1 with compressed air. FIG. 6A shows valve opening / closing timings when the intake / exhaust valves 2 and 3 are driven by fixed cams and the compressed air control valve 11 is driven by an actuator 12. The compressed air control valve 11 is controlled to open in the expansion stroke, and compressed air is discharged into the cylinder in the expansion stroke. FIG. 6B shows the in-cylinder pressure with respect to the crank angle when the engine 1 is driven by compressed air. When the compressed air control valve 11 is opened and the compressed air is discharged into the cylinder, the cylinder pressure rises. FIG. 6C is a PV diagram when the engine 1 is driven by compressed air. In FIG. 6C, as shown by the oblique lines, the cylinder pressure is increased by the compressed air in the expansion stroke, so that a force for pushing down the piston 7 is obtained, which becomes a driving force. That is, the driving force increases as the cylinder pressure increases due to the discharge of compressed air.

  FIG. 7 shows a reference example of the present invention, and is a timing chart showing characteristics of each parameter when switching from the engine running in the compressed air drive mode to the combustion drive mode in which the engine runs by combustion. When switching from the compressed air drive mode to the combustion drive mode as shown in FIG. 7A, if the intake air amount corresponding to the required engine load (engine torque) is realized by the throttle, the negative pressure development is delayed. Alternatively, even if an attempt is made to control the air amount by changing the valve closing timing of the intake valve 2 by the variable valve mechanism as described above, there is a case where the target intake air amount cannot be controlled due to an operation response delay or the like. In this case, the combustion torque may be insufficient or misfire may cause rapid deceleration, or by increasing the fuel injection amount to prevent it, the combustion torque may increase rapidly, resulting in absorption acceleration or shock. BMEP is an average effective pressure of torque generated by the engine. In addition, as shown in FIG. 7B, when the intake air amount is controlled in accordance with the engine torque during the compressed air drive mode, the inflow amount of compressed air increases correspondingly with an increase in pump loss, and the fuel efficiency improvement effect is achieved. It will decline. In other words, as shown in FIG. 7 (b), when considering the switching between the compressed air drive mode and the combustion drive mode and the intake air amount required in the combustion drive mode also in the compressed air drive mode, the pump loss increases, IMEP increases.

  FIG. 8 is a timing chart showing characteristics of each parameter when switching from the engine running in the compressed air drive mode to the combustion drive mode in which the engine runs by combustion in the first embodiment of the present invention.

  In the first embodiment of the present invention, prior to switching from the compressed air drive mode to the combustion drive mode, the intake air amount is controlled toward the target intake air amount after switching, and an increase in pump loss before switching is suppressed. In order to achieve this, the time required to control the intake air amount is estimated. And, by controlling the intake air amount within the optimal time estimated before the mode change as the control amount change condition (control toward the intake air amount in the combustion drive mode), it is possible to suppress the increase in pump loss before the change It is said. It should be noted that the same effect can be obtained by handling the number of cycles instead of time as the control amount changing condition. In other words, even if the number of cycles required to control the intake air amount is estimated and the intake air amount is controlled within the optimum number of cycles estimated before switching as the control amount change condition, the increase in pump loss before switching is suppressed. Is feasible. Note that IMEP in FIG. 8 is an average effective pressure of torque for driving the engine. Therefore, this IMEP includes engine friction (mechanical friction, pumping loss, etc.) when the engine is driven.

  FIG. 9 shows a flowchart relating to determination of the control amount change condition in the first embodiment of the present invention.

  In S101, the engine rotation, the accelerator opening, and the tank pressure of the compressed air storage tank 10 are read.

  In S102, it is determined whether or not it is a compressed air drive mode in which compressed air in the compressed air storage tank 10 is discharged into the cylinder in the expansion stroke. If it is in the compressed air drive mode, the process proceeds to S103, and it must be in the compressed air drive mode. If this is the case, the current routine is terminated.

  In S103, the amount of intake air required when the engine is running due to combustion (in the combustion drive mode) is calculated from the accelerator opening and the engine speed, and is required in the combustion drive mode from the intake air amount in the compressed air drive mode. The target air amount arrival time until the intake air amount is reached is estimated, and the remaining compressed air drive time that is the time during which the compressed air drive mode can be maintained is estimated from the required engine torque and the tank pressure of the compressed air storage tank 10. Since these use parameters correlated with each other, estimation can be performed with high accuracy.

  In S104, if the remaining compressed air drive time is equal to or less than the target air amount arrival time, it is determined that the control amount change condition is satisfied, and the process proceeds to S105. Otherwise, the current routine is terminated.

  Here, if the remaining compressed air drive time is not less than the target air amount arrival time and the difference is equal to or less than a predetermined value (a predetermined value as a width considering the estimation error), it is determined that the control amount change condition is satisfied. The process proceeds to S105, and if not, the current routine may be terminated.

  That is, the remaining compressed air drive time is the target air amount in consideration of the possibility that the target air amount arrival time cannot be accurately calculated for the intake air amount, and the compressed air drive remaining time is the tank pressure of the compressed air storage tank 10. A predetermined value is set as a width that takes into account the estimation error, not when it is less than the arrival time (remaining compressed air drive time−target air amount arrival time ≦ 0), and the remaining compressed air drive time does not fall below the target air amount arrival time When the difference in the range is equal to or less than a predetermined value (compressed air drive remaining time−target air amount arrival time ≦ predetermined value), it may be determined that the control amount change condition is satisfied. Note that S104 in FIG. 9 shows a case where the predetermined value in the remaining compressed air drive time−the target air amount arrival time ≦ the predetermined value is zero.

  In S105, control of the required intake air amount (required intake air amount in the combustion drive mode) is started.

  FIG. 10 is a characteristic diagram used for calculating the intake air amount, the target air amount arrival time, and the compressed air drive remaining time. When the intake air amount is adjusted by the throttle, the throttle operation response delay time can be simply estimated by folding the throttle into the MAP in advance. The intake air amount here is the intake air amount required during the combustion drive mode, which is determined by operating conditions, for example, the engine speed and the accelerator opening. In the first embodiment, this intake air amount is substituted for the engine load.

  In such a first embodiment, rapid acceleration / deceleration due to excessive or insufficient engine torque at the time of switching can be suppressed, and an increase in pump loss during the compressed air drive mode before switching can be suppressed.

  9 and 10, the compressed air storage tank 10 is a constant volume tank. Therefore, for example, when a constant pressure tank is used as the compressed air storage tank 10, the same effect can be obtained by calculating each parameter according to the tank capacity instead of the tank pressure. In addition, the throttle opening may be used instead of the accelerator opening. In this case, the same effect can be obtained by calculating each parameter according to the throttle opening instead of the accelerator opening.

  Then, in S103 of FIG. 9, the compressed air drive remaining cycle and the target air amount arrival cycle are calculated instead of the compressed air drive remaining time and the target air amount arrival time, and the compressed air drive remaining cycle and the target air amount arrival cycle are calculated. By comparing, it may be determined whether the control amount changing condition is satisfied.

  In the first embodiment described above, the target air amount arrival time can also be calculated from the engine torque and the engine speed. For example, as shown in FIG. 11A, the engine torque is calculated from the accelerator opening and the engine rotation speed, and IMEP (average effective pressure of torque for driving the engine with compressed air) is calculated from the engine torque. Then, as shown in FIG. 11B, the target air arrival time can also be calculated from IMEP and the engine speed. IMEP can be calculated with a simple configuration by obtaining the engine friction and the like with respect to the engine speed in advance by MAP.

  Next, a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment described above in the control amount change condition.

  In order to adjust the intake air amount when the control amount changing condition is satisfied, the pump loss increases as the negative pressure develops with respect to the target intake air amount. Therefore, the torque for driving the engine in the compressed air drive mode increases, and the amount of compressed air flowing in increases. And the decreasing rate of the tank pressure of the compressed air storage tank 10 becomes large. When the compressed air storage tank 10 is a constant pressure tank, the rate of tank capacity reduction increases due to an increase in pump loss.

Therefore, in the second embodiment, the remaining compressed air time is estimated with higher accuracy by considering the pump loss that increases from the satisfaction of the control amount change condition to the switching. FIG. 12 shows the second embodiment of the present invention. It is a flowchart regarding determination of the control amount change condition in FIG.

  In S201, the engine rotation, the accelerator opening, and the tank pressure of the compressed air storage tank 10 are read.

  In S202, it is determined whether or not it is a compressed air driving mode in which the compressed air in the compressed air storage tank 10 is discharged into the cylinder in the expansion stroke. If it is the compressed air driving mode, the process proceeds to S203, and it must be in the compressed air driving mode. If this is the case, the current routine is terminated.

  In S203, the amount of intake air required when the engine is running due to combustion (in the combustion drive mode) is calculated from the accelerator opening and the engine speed, and required in the combustion drive mode from the amount of intake air in the compressed air drive mode. The target air amount arrival time until the intake air amount is reached is estimated, and the remaining compressed air drive time, which is the time during which the compressed air drive mode can be maintained, is estimated from the required engine torque and the tank pressure of the compressed air storage tank 10. Further, IMEP (ΔIMEP) that increases from when the control amount changing condition is satisfied until switching is calculated from the intake air amount and the engine speed, and the compressed air drive remaining time correction is performed from this ΔIMEP and the tank pressure of the compressed air storage tank 10. Calculate the value.

  In S204, the second compressed air driving remaining time is obtained by subtracting the compressed air driving remaining time correction value from the compressed air remaining driving time.

  In S205, if the difference becomes the minimum within the range where the second remaining compressed air drive time is not less than the target air amount arrival time, it is determined that the control amount change condition is satisfied, and the process proceeds to S206. finish.

  In S206, control of the required intake air amount (required intake air amount in the combustion drive mode) is started.

  FIG. 13 is a characteristic diagram used to calculate ΔIMEP and the compressed air drive remaining time correction value.

  In such a second embodiment, as shown in FIG. 13 (a), IMEP (ΔIMEP), which increases from the satisfaction of the control amount change condition to the switching, is changed from the required intake air amount correlated with the pump loss to the engine. Estimate using rotational speed. Then, as shown in FIG. 13 (b), the compressed air drive remaining time correction value is calculated from this ΔIMEP and the tank pressure of the compressed air storage tank 10. By correcting the compressed air drive remaining time with this compressed air drive remaining time correction value to obtain the second compressed air drive remaining time, it is possible to accurately estimate the time that can be driven with compressed air.

  In the second embodiment, as in the first embodiment, each parameter is calculated using a constant pressure tank as the compressed air storage tank 10 or using the throttle opening instead of the accelerator opening. May be.

  In S203 of FIG. 12, instead of the compressed air drive remaining time, the target air amount arrival time, and the compressed air drive remaining time correction value, the compressed air drive remaining cycle, the target air amount arrival cycle, and the compressed air drive remaining cycle correction value are set. In step S204, the second compressed air drive remaining cycle is calculated by subtracting the compressed air drive remaining cycle correction value from the compressed air driven remaining cycle, and the second compressed air driven remaining cycle is compared with the target air amount reaching cycle. Thus, it may be determined whether or not the control amount changing condition is satisfied.

  Next, a third embodiment of the present invention will be described. The third embodiment is different from the first embodiment described above in the control amount change condition.

  FIG. 14 shows a flowchart relating to determination of the control amount change condition in the third embodiment of the present invention.

  In S301, the engine rotation, the accelerator opening, and the tank pressure of the compressed air storage tank 10 are read.

  In S302, it is determined whether or not it is a compressed air drive mode in which compressed air in the compressed air storage tank 10 is discharged into the cylinder in the expansion stroke. If it is the compressed air drive mode, the process proceeds to S303, and the compressed air drive mode must be set. If this is the case, the current routine is terminated.

  In S303, the intake air amount required when the engine is driven by combustion (in the combustion drive mode) is calculated from the accelerator opening and the engine speed, and is required in the combustion drive mode from the intake air amount in the compressed air drive mode. Estimate the target air amount arrival time until the intake air amount is reached. Further, the correction switching IMEP is calculated from the target air amount arrival time and the tank pressure in the compressed air storage tank 10.

  Further, the engine torque (switching IMEP) that can be generated is estimated whether the compressed air drive mode is possible in accordance with the tank pressure of the compressed air storage tank 10 with respect to the required engine torque. That is, IMEP (average effective pressure of torque for driving the engine with compressed air) is calculated from the engine torque calculated from the accelerator opening and the engine rotation speed, and this IMEP and the tank in the compressed air storage tank 10 are calculated. The switching IMEP is calculated from the pressure.

  In S304, the corrected switching IMEP is calculated by subtracting the corrected switching IMEP from the switching IMEP.

  In S305, the corrected IMEP and the required IMEP (IMEP at the required engine torque, that is, the IMEP in the compressed air drive mode) are compared. If the corrected IMEP is equal to or greater than the required IMEP, the control amount is changed. It is determined that the condition is satisfied, and the process proceeds to S105. Otherwise, the current routine is terminated.

  FIG. 15 is a characteristic diagram used for calculation of the correction switching IMEP and the post-correction switching IMEP. As shown in FIG. 15A, the correction switching IMEP can be accurately estimated because the tank pressure of the compressed air storage tank 10 and the target air amount arrival time correlated with the compressed air driving time are used. Further, as shown in FIG. 15B, since the correction IMEP corresponding to the tank pressure of the compressed air storage tank 10 is corrected, it is possible to accurately estimate the corrected switching IMEP in consideration of the control amount change condition.

  In the third embodiment as well, similar to the first embodiment described above, rapid acceleration / deceleration due to excessive or insufficient engine torque at the time of switching can be suppressed, and increase in pump loss during the compressed air drive mode before switching is suppressed. it can.

  In the third embodiment, as in the first embodiment described above, each parameter is calculated using a constant pressure tank as the compressed air storage tank 10 or using the throttle opening instead of the accelerator opening. May be.

  In S303 of FIG. 14, it is also possible to calculate the target air amount reaching cycle instead of the target air amount reaching time, and calculate the correction switching IMEP from the target air amount reaching cycle and the tank pressure of the compressed air storage tank 10. It is.

  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 control valve for controlling the inflow of air into the cylinder other than the intake and exhaust valves, a tank for storing compressed air communicated with the control valve, and a state in the tank In-tank state measuring means for measuring the intake, target intake air amount determining means for determining the amount of air sucked into the cylinder through the intake valve, and intake air amount control means for controlling the intake air amount, and driven by combustion Mode switching means for switching between a combustion drive mode to be performed and a compressed air drive mode to be driven by allowing compressed air to flow into the cylinder from the control valve, and from the control valve to the cylinder during the compressed air drive mode. Target inflow air amount determination means for determining the amount of air to be introduced; inflow air amount control means for controlling the amount of air that flows into the cylinder by opening and closing the control valve at least in the expansion stroke; In serial air driven mode in and a control amount change determining means for performing control amount change of the intake air amount control means. As a result, the control amount change condition for the intake air amount is changed according to the operating condition, so that the intake air amount corresponding to the required engine load is obtained even when the engine drive is switched from the compressed air drive mode to the combustion drive mode. As a result, excessive or insufficient engine torque and misfire can be suppressed, and an increase in pump loss during the compressed air drive mode before switching can be suppressed.

  (2) Specifically, the control device for an internal combustion engine according to the above (1) changes the control amount change determination according to operating conditions and the state in the tank.

  (3) The control device for an internal combustion engine according to the above (1) or (2) includes a compressed air amount control valve for controlling a compressed air amount between the tank and the control valve, and is provided in the cylinder from the control valve. The opening and closing of the compressed air amount control valve is controlled according to the target inflow air amount to be introduced. Thus, the target inflow air amount necessary during the compressed air drive mode is controlled in advance by the compressed air flow rate control valve, so that the control valve only needs to control the timing of inflow into the cylinder, and allows the compressed air to flow in accurately. be able to.

  (4) In the control apparatus for an internal combustion engine according to any one of (1) to (3), the control amount change determining unit calculates a remaining time during which the engine can be driven in the compressed air drive mode during the compressed air drive mode. Compressed air drive remaining time calculating means, target air amount arrival time calculating means for calculating a time required to reach a target intake air amount corresponding to an engine load in the combustion drive mode during the compressed air drive mode, and the control amount Control amount change execution determination means for determining execution of change, and in the compressed air drive mode, the difference is less than or equal to a predetermined value within a range in which the remaining compressed air drive time does not fall below the target air amount arrival time When it becomes, it determines with implementation of the said control amount change. As a result, the execution of the control amount change is determined so that the time that can be driven with compressed air is less than the predetermined value within a range that does not fall below the time until the target intake air amount is reached. It can be prevented that it can not be driven by compressed air from the start to the next switching, and the increase in pump loss can be minimized.

  (5) In the control apparatus for an internal combustion engine according to (4), the predetermined value is determined according to the estimation accuracy of the remaining compressed air drive time and the estimation accuracy of the target air amount arrival time. As a result, the predetermined value is set according to the calculation accuracy of the control amount change condition, so that the change timing of the control amount change condition can be optimally determined.

  (6) In the control device for an internal combustion engine according to (4), the remaining compressed air drive time is a cycle corresponding to a remaining time that can be driven with compressed air from a time when the remaining compressed air drive time is calculated. It is a number. As a result, since a parameter having a correlation with the in-tank state is used, it can be estimated with high accuracy.

  (7) In the control device for an internal combustion engine according to (4), the target air amount arrival time corresponds to a time from when the target air amount arrival time is calculated to a time when the target intake air amount is reached. The number of cycles. As a result, a parameter having a correlation with the development of the negative pressure is used, so that it can be estimated with high accuracy.

  (8) In the control device for an internal combustion engine according to any one of (4) to (6), the remaining compressed air drive time depends on a tank pressure or a tank volume, an engine load, and an engine speed. Set. As a result, since a parameter having a correlation with the remaining compressed air drive time is used, the time can be estimated with high accuracy.

  (9) In the control device for an internal combustion engine according to (8), the compressed air drive remaining time is shorter as the engine load is higher, the tank pressure is lower, or the engine speed is higher. As a result, the higher the engine load, the lower the tank pressure, or the higher the engine speed, the lower the tank pressure in the constant volume tank and the lower the tank capacity in the constant pressure tank. Thus, it is possible to prevent the compressed air drive from being disabled while changing the control amount of the intake air amount.

  (10) In the control apparatus for an internal combustion engine according to any one of (4) to (7), the target air amount arrival time depends on at least one of a required intake air amount or an engine load and an engine speed. To set. Accordingly, since at least one parameter of the engine rotation speed, the engine load, and the required intake air amount correlated with the target air amount arrival time is used, the time can be estimated with high accuracy.

  (11) In the control apparatus for an internal combustion engine according to (10), the target air amount arrival time is shorter as the engine rotational speed is higher, the required intake air amount is larger, or the engine load is larger. As a result, the higher the engine speed, the faster the target air amount is reached, and the larger the engine load or intake air amount, the smaller the amount of change from the throttle fully open, so by shortening the target air amount arrival time, An increase in pump loss during the change of the control amount of the intake air amount can be minimized.

  (12) In the control apparatus for an internal combustion engine according to (1) or (2), the intake air amount control means is at least one of throttle throttle opening, intake valve closing timing, and intake valve lift amount. To control. Thus, the target intake air amount can be realized by adjusting the control amount.

  (13) In the control device for an internal combustion engine according to the above (1) or (2), the inflow air amount control means is based on actuator driving by electromagnetic force or hydraulic pressure, or changes the cam phase by cam driving. At least one of a cam drive that switches the use of a plurality of cams having different profiles and a cam drive that operates fixedly is used. As a result, by adjusting the control amount, the target inflow air amount into the cylinder can be realized.

  (14) In the control device for an internal combustion engine according to the above (1) or (2), the tank is a constant volume tank that stores compressed air at a constant capacity. Thus, the storage tank can be simplified by using a constant volume tank.

  (15) In the control device for an internal combustion engine according to any one of (1), (2), and (14), the tank internal state measuring means is at least one of tank internal air pressure and tank internal air temperature. Measure one. Accordingly, the in-tank state can be accurately estimated by measuring at least one parameter representing the in-tank state.

  (16) In the control device for an internal combustion engine according to (1) or (2), the tank is a constant pressure tank that stores compressed air at a constant pressure. Thereby, the control performance of the inflow air amount is improved by using the constant pressure tank, and the driving range by the compressed air can be expanded.

  (17) In the control device for an internal combustion engine according to any one of (1), (2) and (16), the in-tank state measuring means is at least one of tank air capacity and tank air temperature. Measure one. Accordingly, the in-tank state can be accurately estimated by measuring at least one parameter representing the in-tank state.

The explanatory view showing the outline of one embodiment of the present invention typically. The system block diagram which showed the control amount change determination means in FIG. 1 in detail. Explanatory drawing which shows schematic structure of the engine in embodiment of this invention. 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. It is explanatory drawing explaining the outline of the engine drive by the compressed air in a reference example, Comprising: (a) is explanatory drawing which showed the valve timing of an intake valve, an exhaust valve, and a compressed air control valve typically, (b) is a crank The characteristic diagram which shows the relationship between an angle | corner and a cylinder internal pressure, (c) is a PV diagram at the time of discharging compressed air in a cylinder. In a reference example, it is a timing chart which shows the characteristic of each parameter at the time of switching from compressed air drive mode to combustion drive mode, (a) shows the case where excess and deficiency occurs in combustion torque at the time of switching, (b) The case where the pump loss increases during the compressed air drive mode is shown. The timing chart which shows the characteristic of each parameter at the time of switching from the compressed air drive mode to the combustion drive mode in 1st Embodiment of this invention. The flowchart regarding the determination of the control amount change condition in the first embodiment of the present invention. (A) is a characteristic diagram used for calculating the intake air amount, (b) is a characteristic diagram used for calculating the target air amount arrival time, and (c) is a characteristic diagram used for calculating the remaining compressed air drive time. (A) is a characteristic diagram used when calculating the engine torque from the accelerator opening and the engine rotational speed, and (b) is a characteristic diagram used when calculating the target air amount arrival time from the IMEP and the engine rotational speed. The flowchart regarding determination of the control amount change condition in 2nd Embodiment of this invention. (A) is a characteristic diagram used for calculating ΔIMEP, and (b) is a characteristic diagram used for calculating a compressed air drive remaining time correction value. The flowchart regarding the determination of the control amount change condition in the third embodiment of the present invention. (A) is a characteristic diagram used for calculation of correction switching IMEP, (b) is a characteristic diagram used for calculation of post-correction switching IMEP.

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

Claims (17)

A control valve for controlling the inflow of air into the cylinder other than the intake and exhaust valves;
A tank for storing compressed air in communication with the control valve;
In-tank state measuring means for measuring the state in the tank;
Target intake air amount determination means for determining the amount of air to be sucked into the cylinder through the intake valve;
An intake air amount control means for controlling the intake air amount,
Mode switching means for switching between a combustion drive mode driven by combustion and a compressed air drive mode driven by flowing compressed air from the control valve into the cylinder according to operating conditions;
Target inflow air amount determining means for determining the amount of air that flows into the cylinder from the control valve during the compressed air drive mode;
Inflow air amount control means for controlling the amount of air flowing into the cylinder by opening and closing the control valve at least in the expansion stroke;
And a control amount change determining means for changing the control amount of the intake air amount control means during the compressed air drive mode.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the control amount change determination is changed according to an operating condition and a state in the tank. A compressed air amount control valve for controlling the amount of compressed air between the tank and the control valve;
3. The control device for an internal combustion engine according to claim 1, wherein opening and closing of the compressed air amount control valve is controlled in accordance with a target inflow air amount that flows into the cylinder from the control valve.   The control amount change determining means is responsive to a compressed air drive remaining time calculating means for calculating a remaining time that can be driven in the compressed air drive mode during the compressed air drive mode, and an engine load in the combustion drive mode during the compressed air drive mode. A target air amount arrival time calculating means for calculating a time until the target intake air amount is reached, and a control amount change execution determining means for determining execution of the control amount change, during the compressed air drive mode. The control amount change is determined to be performed when the difference is equal to or less than a predetermined value within a range in which the remaining compressed air drive time does not fall below the target air amount arrival time. A control device for an internal combustion engine according to claim 1.   5. The control apparatus for an internal combustion engine according to claim 4, wherein the predetermined value is determined according to the estimation accuracy of the remaining compressed air drive time and the estimation accuracy of the target air amount arrival time.   5. The internal combustion engine according to claim 4, wherein the remaining compressed air drive time is a cycle number corresponding to a remaining time that can be driven by compressed air from a time when the remaining compressed air drive time is calculated. Control device.   5. The internal combustion engine according to claim 4, wherein the target air amount arrival time is a cycle number corresponding to a time from when the target air amount arrival time is calculated to a time until the target intake air amount is reached. Control device.   The control apparatus for an internal combustion engine according to any one of claims 4 to 6, wherein the remaining compressed air drive time is set according to a tank pressure or a tank volume, an engine load, and an engine speed.   The control apparatus for an internal combustion engine according to claim 8, wherein the remaining compressed air drive time is shorter as the engine load is higher, the tank pressure is lower, or the engine speed is higher.   The control apparatus for an internal combustion engine according to any one of claims 4 to 7, wherein the target air amount arrival time is set according to at least one of a required intake air amount or an engine load and an engine speed. .   11. The control device for an internal combustion engine according to claim 10, wherein the target air amount arrival time is shorter as the engine rotational speed is higher, the required intake air amount is larger, or the engine load is larger.   The control device for an internal combustion engine according to claim 1 or 2, wherein the intake air amount control means controls at least one of a throttle throttle opening, an intake valve closing timing, and an intake valve lift amount. .   The inflow air amount control means is driven by an actuator driven by electromagnetic force or hydraulic pressure, changes the phase of the cam by cam drive, switches the use of a plurality of cams having different profiles by cam drive, and cam drive that operates fixedly The control apparatus for an internal combustion engine according to claim 1 or 2, wherein at least one of the above is used.   3. The control device for an internal combustion engine according to claim 1, wherein the tank is a constant volume tank that stores compressed air with a constant capacity.   15. The control device for an internal combustion engine according to claim 1, wherein the in-tank state measuring unit measures at least one of an in-tank air pressure and an in-tank air temperature.   3. The control device for an internal combustion engine according to claim 1, wherein the tank is a constant pressure tank that stores compressed air at a constant pressure.   17. The control apparatus for an internal combustion engine according to claim 1, wherein the in-tank state measuring unit measures at least one of an in-tank air capacity and an in-tank air temperature.

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