JP2008115829A - Control device and control method of reciprocation type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce or eliminate torque fluctuations caused by delays in response of an intake-air flow associated with a change in throttle openings. <P>SOLUTION: An electrically-controlled air intake passage used for opening and closing an intake-air passage and a double-link-type piston-crank mechanism are provided, and the piston motion of the double-link-type piston-crank mechanism changes in accordance with a position of a link-supporting part. Then the intake-air flow is adjusted by controlling the piston motion and the throttle openings. During a period of transition of acceleration from a low-load zone to a middle-load zone which increases the throttle openings without changing the piston motion, the intake stroke amount of the piston motion is temporarily increased, and the delays in response to an increase in an intake-air flow associated with an increase in throttle openings can be reduced or offset. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to control of a reciprocating internal combustion engine that can change the piston motion of a piston that reciprocates in a cylinder using a multi-link piston-crank mechanism.

  Patent Document 1 discloses an example of a multi-link piston-crank mechanism of a reciprocating internal combustion engine that can change an engine compression ratio with a change in piston motion. In this mechanism, the piston that reciprocates in the cylinder and the crank pin of the crankshaft are linked by a plurality of links, and the position of the link support portion of the control link connected to one of the plurality of links is changed and held by an actuator. By doing so, it is possible to change the engine compression ratio in accordance with the change of the piston motion with respect to the crank angle, that is, the piston motion.

Patent Document 2 discloses an example of a multi-link piston-crank mechanism of a reciprocating internal combustion engine that can similarly change the piston motion. In this mechanism, the piston that reciprocates in the cylinder and the crank pin of the crankshaft are linked by a plurality of links, and the link support portion of the control link coupled to one of the plurality of links is slidable on the guide member. It is supported. The guide member is swingably supported by the cylinder block. By changing the fixing position of the guide member, the piston is reciprocated according to the crank angle, and the piston is moved regardless of the crank angle. It is possible to switch between the piston stopped state held in the stopped state.
JP 2003-201875 A JP 2005-140108 A

  In a control apparatus for a reciprocating internal combustion engine having such a multi-link type piston-crank mechanism, generally, as described in Patent Document 1 and Patent Document 2, according to the load in order to improve thermal efficiency. The piston motion is changed. However, depending on the load region, there is a region where the torque cannot be controlled only by the piston motion, that is, a region where an intake air amount (hereinafter also simply referred to as an intake air amount) corresponding to the required torque cannot be obtained. In such a region, the intake air amount is controlled by using an electrically controlled throttle valve that opens and closes the intake passage, but the torque control by the throttle valve control is based on changes in the intake air amount with respect to changes in the throttle opening. There is an unavoidable time delay and response delay, and torque fluctuation caused by the delay may give the vehicle occupant an uncomfortable feeling.

  In addition, the change in the intake air amount due to the change in the throttle opening is much less responsive than the change in the intake air amount due to the change in the piston motion. When there is a setting where there is a region where the air intake is changed and a region where the intake air amount is changed only by the throttle valve, the torque response will differ depending on the operation region, and specifically, the intake air amount is adjusted by the throttle valve. In the region, the responsiveness of the intake air amount during the acceleration / deceleration transition period in which the load changes tends to be lower than in the region where the intake air amount is controlled by the piston motion.

  The present invention has been made in view of such problems, and a control link is provided as one of a plurality of links that link an electrically controlled throttle valve that opens and closes an intake passage and a piston and a crankpin of a crankshaft. Applied to a four-cycle reciprocating internal combustion engine having a coupled multi-link piston-crank mechanism and an actuator for changing / holding the position of the link support portion of the control link, and depending on the position of the link support portion It is possible to adjust the amount of intake air by controlling the piston motion that changes and the throttle opening of the throttle valve. Then, the piston motion is temporarily changed so as to cancel out the torque fluctuation accompanying the change in the throttle opening during the transition period in which the throttle opening is changed according to the engine operating state.

  According to the present invention, the change in the throttle opening is performed by temporarily changing the piston motion in a transition period in which the throttle opening is changed according to the engine operating state, for example, in an acceleration transition period from a low load. As a result, it is possible to satisfactorily absorb and cancel the torque fluctuation caused by the intake air amount, that is, the torque response delay, and improve the torque response performance.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIGS. 1 and 2, this internal combustion engine (engine) is a four-cycle spark-ignition type four-cylinder reciprocating internal combustion engine in which four strokes of expansion, exhaust, intake, and compression are defined as one cycle. A crankshaft 11 as an engine output shaft is rotatably supported on the cylinder block 10, and a plurality of pistons 12 are fitted in such a manner that they can reciprocate, in this example, four # 1 to # 4 cylinders (cylinders). 13 is formed. The cylinder head 14 fixed to the upper portion of the cylinder block 10 is formed with a pent roof type combustion chamber 15 between the crown surface of the piston 12 and an intake valve 17 for opening and closing an intake passage (intake port) 16. And an exhaust valve 19 for opening and closing an exhaust passage (exhaust port) 18 and an ignition plug 20 for spark-igniting the air-fuel mixture in the combustion chamber 15 are provided.

  The intake passage 16 is provided with an electrically controlled throttle valve 41 whose opening degree can be adjusted and controlled according to a control signal from the control unit 40, and an intake air amount (intake) upstream of the throttle valve 41. An air flow meter 42 for detecting an air amount) is provided, and an injector (fuel injection valve) 43 for injecting fuel into the intake port is provided. As sensors for detecting the engine operating state, an accelerator opening sensor 44 for detecting an accelerator operation amount (accelerator opening) by a driver, a crank angle sensor 45 for detecting a rotation angle of the crankshaft 11, that is, a crank angle (CA), A cam angle sensor 47 for detecting the rotation angle of the cam shaft, a water temperature sensor 46 for detecting the coolant temperature as the engine temperature, a vehicle speed sensor 50 for detecting the vehicle speed, the air flow meter 42, and the like are provided. Cylinder discrimination and engine speed detection are performed by a combination of 45 and the detection signal of the cam angle sensor 47.

  The control unit 40 is a digital computer system having a function of storing and executing various control processes. In addition to the detection signals from the sensors, the control unit 40 is a throttle valve based on an engine start signal from a starter switch (SW) 48 and the like. 41, an injector 43, a spark plug 20, a starter 49 that rotationally drives or cranks the crankshaft 11 when the engine is started, and a plurality of multi-link piston-crank mechanisms 21 provided for each cylinder as described later (this embodiment) In the example, a control signal is output to four actuators 27 and the like to control the operation. In particular, the adjustment of the intake air amount is performed by controlling the piston motion that changes according to the position of the link support portion 26 and the throttle opening of the throttle valve 41.

  The battery 52 stores electric power generated by an alternator and a motor generator (not shown). The starter 49 and auxiliary equipment such as an air conditioner / compressor (not shown) are driven by electric power (voltage / current) supplied from the battery 52. The storage state of the battery 52, that is, the voltage that can be supplied, is detected and monitored by a battery controller (battery state detection means) 53.

  As shown in FIG. 2, the multi-link type piston-crank mechanism 21 links each piston 12 and the crank pin 22 of the crankshaft 11 by a plurality of links 23 and 24, and one of the plurality of links 23 and 24. The piston motion (PM) of the piston 12 can be changed by changing the position of the link support portion 26 of the control link 25 connected to the actuator 27 by the actuator 27. More specifically, the multi-link type piston-crank mechanism 21 includes a lower link 23 that is rotatably attached to the crankpin 22, an upper link 24 that connects the lower link 23 and the piston 12, and one end that is a lower link. The control link 25 is rotatably connected to the control link 25, and the link support portion 26 is provided at the other end of the control link 25. The piston 12 and the upper end of the upper link 24 are connected by a piston pin 28, the lower end of the upper link 24 and the lower link 23 are connected by a first connecting pin 29, and one end of the lower link 23 and the control link 25. Are connected by a second connecting pin 30. The lower link 23 mechanically includes a first arm 31 that connects the first connecting pin 29 and the second connecting pin 30, a second arm 32 that connects the first connecting pin 29 and the crank pin 22, and a second connection. And a third arm 33 connecting the pin 30 and the crank pin 22. The actuator 27 is provided for each cylinder 13 in this example.

  The actuator 27 may be a linear actuator using a linear motor (linear induction motor) that is electrically controlled. The linear actuator 27 is, for example, a guide rail 34 as a linear stator fixed to the inner surface of the cylinder block 10, and supported by the guide rail 34 so as to be capable of reciprocating linear movement. An armature and a magnetic field are respectively provided in the link support portion 26 as a mover that travels along the linear direction L1 parallel to the direction, and a cable 35 for supplying an induced current or the like to the link support portion 26. Is connected. Such a linear actuator 27 makes it possible to change the piston motion quickly and accurately according to the operating conditions and the number of revolutions, and the link support 26 can be accurately operated even during high-speed rotation of the engine. High speed and high accuracy can be realized, and friction of the link support portion 26 can be reduced. Note that a position sensor 51 for detecting the position of the link support portion 26 is preferably provided in order to accurately control the link support portion 26 for each cylinder by known feedback control or the like according to the crank angle.

  However, instead of such a linear actuator 27, a hydraulic actuator including an electromagnetic valve that controls hydraulic pressure and a hydraulic piston that operates by hydraulic pressure may be applied. By using a hydraulic actuator that controls the hydraulic pressure with such a solenoid valve and moves the link support portion directly with a hydraulic piston, the cost can be reduced and the operation with a large torque can be performed stably. It becomes possible.

  Moreover, it is good also as a structure using a magnetorheological fluid as an actuator. That is, the magnetorheological fluid is connected so as to suppress the speed of the link support portion 26 in the operation direction, and the motion of the link support portion 26 is changed by the force applied to the link support portion 26. The piston motion can be switched by changing the viscosity of the current flowing through the electromagnet according to the operating conditions. In this case, the mechanism is simple and the cost can be reduced.

  FIG. 3 shows a setting example of the link support portion 26 with respect to the crank angle, and FIG. 4 shows the position / operation of the piston 12 with respect to the crank angle, that is, the piston motion. In the figure, H1 indicates the first setting used in the medium to high load range, and H2 indicates the second setting used in the low to medium load range. In these first and second settings, the intake stroke amount (which is simply referred to as “intake S amount” in the drawing) is the length of the intake stroke without changing the position of the exhaust top dead center or the position of the expansion bottom dead center. ) IS1, IS2 and the position of compression top dead center are changed. Such settings H1 and H2 can be realized by quickly changing the position of the link support portion 26 in accordance with the crank angle.

  In the first setting H1 used in the medium to high load range, the piston motion is made to have a characteristic close to a single vibration having excellent sound vibration performance, that is, a sine wave, by holding the link support portion 26 at a predetermined position. The position of the piston motion is generally increased as the link support portion 26 is lowered in the cylinder axial direction, and the position of the piston motion is generally decreased as it is raised toward the upper limit position.

  In the second setting H2 used in the low / medium load range, the link support 26 is reciprocated to the lower side of the cylinder only during a predetermined operation period from the intake stroke to the expansion stroke in each cycle. Thus, in particular, the stroke amount of the intake stroke of the piston, that is, the intake stroke amount IS2 is made sufficiently smaller than the intake stroke IS1 in the first setting H1. Further, the compression top dead center position is made higher and the engine compression ratio is made higher than the first setting H1. Accordingly, the compression stroke can be shortened by shortening the intake stroke amount, and the expansion stroke can be lengthened by increasing the compression top dead center position, thereby increasing the thermal efficiency.

  FIG. 5 is a block diagram schematically showing target position calculation processing of the link support section 26 according to the first embodiment of the present invention. This process is stored and executed by the control unit 40. In the required torque calculation unit B1, the required torque (tTe) is obtained from the accelerator opening (APO) and the engine speed (Ne). As an example, the required torque (tTe) is set with reference to a control map set in advance as shown in FIG.

  In the target throttle opening / target intake stroke amount calculation unit B2, the target throttle opening (tTVO) and the target intake stroke amount (from the required torque (tTe) obtained by the request torque calculation unit B1 and the engine speed (Ne) are calculated. tQcyl0) is obtained. As an example, a target throttle opening (tTVO) and a target intake stroke amount (tQcyl0) are obtained with reference to a control map that is set in advance as shown in FIG. As shown in FIG. 7, in the middle to high load range, the throttle opening is fully opened, and the intake air amount is adjusted by increasing or decreasing the intake stroke amount. Specifically, the intake stroke amount is increased as the required torque (load) is higher. In the low to medium load range, the intake stroke amount is fixed to the minimum value, and the intake air amount is adjusted by increasing or decreasing the throttle opening. Specifically, the throttle opening is increased as the required torque is higher. FIG. 8 shows the relationship between the intake stroke amount and the engine compression ratio. As shown in the figure, the engine compression ratio decreases as the intake stroke amount increases (see FIG. 4).

Referring to FIG. 5 again, the torque change amount correction determination calculation unit B3 uses the required torque (tTe) obtained by the required torque calculation unit B1, and for example, changes in the required torque (predetermined time) according to the following equation (1). (Change amount per interval of Δt) (dTe) is obtained.
dTe = tTe−tTe (Δt) (1)
Further, in this torque change amount correction determination calculation unit B3, in order to cancel and absorb the torque fluctuation caused by the response delay of the intake air amount accompanying the increase or decrease of the throttle opening, based on the change amount (dTe) of the required torque. Then, it is determined whether or not it is an acceleration transition period in which correction of the intake stroke amount is necessary. In this embodiment, this acceleration transition period is the time of acceleration from the low load range to the medium load range where the throttle opening is increased without changing the piston motion, as shown in FIG. The required torque change amount (dTe) is greater than or equal to a predetermined value (Tacc), and from the start of acceleration until the torque change amount (dTe) is less than the predetermined value (Tacc) until a predetermined period (Tdelay) elapses. Corresponds to the period of If it is the acceleration transition period, the correction determination flag Tarea is set to “1” by the routine of FIG. 9 described later, and if it is not the acceleration transition period, the correction determination flag Tare is set to “0”.

  In the target intake stroke amount correction unit B4, when it is determined that the torque change amount correction determination calculation unit B3 is in the acceleration transition period (Tare = 1), for example, the torque deviation (deltaT) and the target are calculated by the following equation (2). The target intake stroke amount (tQcyl0) is corrected using the intake amount correction coefficient (kQcyl), and the final target intake stroke amount (tQcyl) is calculated.

tQcyl = tQcyl0 + kQcyl × deltaT × Tarea (2)
However, tQcyl is set in a range equal to or smaller than a settable upper limit value tQcyl_max. If not in the acceleration transition period, the correction term including the Tarea in the above equation (2) becomes 0, and the target intake stroke amount tQcyl0 is set as it is as the target intake stroke amount tQcyl without being corrected.

  The target intake air amount correction coefficient (kQcyl) is simply set to a fixed value that is adapted in advance through experiments. The torque deviation (deltaT) is obtained from the deviation between the required torque (tTe) and the estimated torque (eTe) (deltaT = tTe−eTe). The estimated torque (eTe) is calculated from the required torque (tTe) in consideration of the engine speed, the intake system delay, and the like. For example, as shown in the following equation (3), the first-order delay is simply processed, and the time constant k is changed according to the operating conditions.

eTe = k × tTe + (1−k) × eTe_old (3)
In the target position calculation unit B5, the target of the link support unit 26 of each cylinder is based on the target intake stroke amount (tQcyl) output from the target intake stroke amount correction unit B4, the crank angle, and the cylinder discrimination result. The position is set with reference to, for example, a preset control map. The actuator 27 is driven and controlled according to this target position, and a piston motion corresponding to the target intake stroke amount is realized.

  FIG. 9 is a flowchart showing a flow of processing for calculating the target intake stroke amount according to the present embodiment. This routine is repeatedly executed by the control unit 40 every predetermined short calculation interval Δt (for example, 10 ms or a predetermined crank angle).

  In step S11, the accelerator opening (APO) and the engine speed (Ne) are read. The accelerator opening is obtained, for example, by detecting the output voltage of the accelerator opening sensor 44 whose resistance value changes according to the opening, and referring to a control map indicating the relationship between the output voltage and the accelerator opening that has been obtained in advance. be able to. The engine speed can be obtained, for example, from the output of the crank angle sensor 45 that generates a pulse for each specific crank angle.

  In step S12, for example, with reference to a control map set in advance, the required torque (tTe) is obtained from the accelerator opening (APO) and the engine speed (Ne). In step S13, using the required torque (tTe) described above, a change amount of the required torque (change amount per predetermined time Δt interval) (dTe) is obtained by, for example, the above equation (1).

  In step S14, it is determined using the amount of change in required torque (dTe) or the like whether or not it is an acceleration transition period in which the intake stroke amount should be corrected. As described above, at the time of acceleration from the low load range to the medium load range where the throttle opening is increased without changing the piston motion, the required torque change amount (dTe) is a predetermined value (Tacc) or more. In addition, it is determined that a period from the start of acceleration until the predetermined time period (Tdelay) elapses after the torque change amount (dTe) becomes less than the predetermined value (Tacc) is determined as the acceleration transition period. Or, more simply, the required torque tTe may be in the low / medium load region where the predetermined value Tmid is equal to or less than the predetermined value Tmid, and the acceleration transition period may be determined within the predetermined period from the acceleration start (dTe ≧ Tacc).

  If the acceleration transition period is determined, the correction determination flag Tarea is set to “1” (step S15), and if it is determined that the normal operation state is other than the acceleration transition period, the correction determination flag Tarea is set to “0” (step S16). . In step S17, for example, the target intake stroke amount (tQcyl0), the torque deviation (deltaT), the target intake amount correction coefficient (kQcyl), and the correction determination flag (Tare) are calculated using the above-described equation (2). tQcyl) is corrected and calculated.

  As described above, according to this embodiment, as shown in FIG. 10, the acceleration transition period from the low load range to the medium load range in which the throttle opening is increased without changing the piston motion in accordance with the increase in the required torque. Furthermore, as shown by the symbol α in the figure, the piston motion is temporarily changed, specifically, the intake stroke amount is temporarily increased, thereby causing a response delay of an increase in the intake amount accompanying an increase in the throttle opening. The shortage of the intake air amount can be compensated, the torque fluctuation can be absorbed and offset well, and the torque response performance can be improved.

  In particular, in this embodiment, the torque deviation (deltaT) corresponding to the shortage of the intake air amount in the acceleration transition period is obtained, and the intake stroke amount of the piston motion is corrected based on this torque deviation. Can be improved.

  In the embodiment described below, portions different from the above-described embodiment will be mainly described, and overlapping description will be omitted as appropriate.

With reference to FIG. 11, the correction processing of the target intake stroke amount in the acceleration transition period from the low load range to the medium load range according to the second embodiment of the present invention will be described. In the second embodiment, the manifold pressure (Pmani) downstream of the throttle valve 41, the throttle passing air amount (Qth), the engine intake air amount (Qeng), and the intake system volume (the volume from the throttle downstream to the intake valve) ( The target intake stroke amount in the acceleration transition period is corrected and calculated based on Vint (fixed value). More specifically, as shown in the following equation (4), the required intake air amount tQcyl necessary for securing the air amount Qeng that can realize the required torque (tTe) is calculated using the manifold pressure (Pmani).
tQcyl = Qeng / Ne × Patm / Pmani (4)
However,
tQcyl ≦ tQcyl_max
Qth = f (Ath, Pmani)
Qeng = f (Qcyl, Pmani, Ne) = Qcyl × Pmani / Patm × Ne
Pmani = f (Qth, Qeng, Pmani_old, Vint)
The amount of air passing through the throttle (Qth) is, for example, Bernoulli using the throttle upstream pressure as the atmospheric pressure (Patm), the manifold pressure (Pmani) downstream of the throttle valve 41, and the throttle valve opening area (Ath). It can be calculated using the following formula. The engine intake air amount (Qeng) is calculated by, for example, the intake stroke volume (Qcyl) and the engine speed (Ne) assuming that the cylinder pressure at the intake bottom dead center is equal to the manifold pressure (Pmani). Can do. The intake system volume (Vint: fixed value) corresponds to the volume from the throttle downstream to the intake valve, and is a fixed value determined by the design value of the intake system. The intake stroke volume (Qcyl) is calculated from the stroke length in the intake stroke and the cross-sectional area of the cylinder. The opening area (Ath) of the throttle valve is proportional to the throttle angle (opening), and can be obtained, for example, by referring to predetermined table data representing the relationship between the two.

  As described above, in the second embodiment, correction (calculation) of the intake stroke amount tQcyl in the acceleration transition period is performed in consideration of the manifold pressure change due to the piston motion change. Can be absorbed and offset.

  With reference to FIGS. 12 and 13, the correction processing of the target intake stroke amount in the acceleration transition period according to the third embodiment of the present invention will be described. In the third embodiment, the required intake air amount tQcyl is corrected and calculated by further taking into account the reduction in efficiency due to the change in the compression ratio accompanying the change in the target intake stroke amount tQcyl. Torque response delay can be reduced or eliminated.

  Specifically, the efficiency (η) corresponding to the current target intake stroke amount is set with reference to the control map shown in FIG. 13 with reference to the time when the target intake stroke amount is the minimum (100%). As shown in the figure, the efficiency η decreases as the intake stroke amount increases.

  Then, using this efficiency η, the target intake stroke amount tQcyl in the acceleration transition period is calculated (corrected) by the following equation (5).

tQcyl = Qeng / Ne × Patm / Pmani / η (5)
(However, tQcyl ≦ tQcyl_max)
A fourth embodiment of the present invention will be described with reference to FIGS. During the acceleration transition period from the low load region, the temperature of the combustion chamber and exhaust valve is lower than that at the time of high load, so there is some room for knocking. Therefore, during such an acceleration transition period, the piston motion at the time of correction indicated by the solid line in FIG. 14 is set higher than the compression ratio corresponding to the required intake air amount tQcyl obtained in the steady state. More specifically, when the piston motion is temporarily changed or corrected so as to cancel the intake response delay due to the change in the throttle opening, the compression top dead center position is increased without changing the intake stroke amount. ing. As a result, it is possible to reduce a decrease in efficiency due to torque correction during transition.

  A fifth embodiment of the present invention will be described with reference to FIGS. In the acceleration transition period from the low load range, there is a possibility that the intake amount for realizing the target torque is insufficient even if the intake stroke amount is set to the upper limit value (tQcyl_max) due to the response delay of the decrease in the intake negative pressure. Therefore, when the piston motion is temporarily changed to cancel the intake response delay due to the change in the throttle opening during the acceleration transition period, as shown by the solid line in FIG. 16, the intake stroke is not changed without changing the stroke amount. The intake air amount is increased by making the crank angle (hereinafter also simply referred to as “intake stroke angle”) smaller than the intake stroke angle obtained in the steady state and increasing the piston speed during the intake stroke. Here, when a mechanism capable of changing the intake valve timing is provided, the intake valve closing timing is preferably changed in accordance with the change in the intake stroke angle so that the intake valve opens according to the intake stroke.

  Note that the intake stroke angle Cint refers to a preset control map as shown in FIG. 17 based on the amount by which the intake stroke amount exceeds the maximum value (tQcyl_max), that is, the target intake stroke amount deficiency value (tQcyl_hos). The minimum value of the intake stroke angle is set in a range where the moving speed of the control shaft does not become too fast and in a range where an effect of increasing the intake air amount can be obtained (Cint = f (tQcyl_hos)). As shown in FIG. 17, the intake stroke angle is reduced as the target intake stroke amount deficiency value (tQcyl_hos) increases.

The target intake stroke amount shortage value (tQcyl_hos) can be obtained by the following equation (6), for example.
tQcyl_hos = (tQcyl0 + kQcyl × deltaT × Trea)
-TQcyl_max (6)
A sixth embodiment of the present invention will be described with reference to FIGS. In the acceleration transition period from the low load range, due to the influence of the response delay of the suction negative pressure drop, there is a possibility that the residual gas becomes more than in the steady state and the combustion becomes unstable. Therefore, the piston motion in the acceleration transition period (see the solid line in FIG. 18) is made longer than the intake stroke angle obtained in the steady state without changing the stroke amount, and the compression stroke crank angle is shortened. In addition, the intake air turbulence during compression is increased by increasing the piston speed during the compression stroke. As a result, stable combustion is possible even in a state where there is a large amount of residual gas. Here, when a mechanism capable of changing the intake valve timing is provided, it is preferable that the intake valve close timing according to the change in the intake stroke angle so that the intake valve opens favorably according to the intake stroke angle. Also change.

  The intake stroke angle Cint is set based on the manifold pressure Pmani as shown in the following equation (7). Specifically, as shown in FIG. 19, the intake stroke angle Cint is longer as the manifold pressure is smaller. Increase piston speed.

Cint = f (Pmani) (7)
The characteristic technical ideas of the present invention that can be understood from the above description are listed. However, the present invention is not limited to the above embodiments, and includes various modifications and changes without departing from the spirit of the present invention. For example, in the above-described embodiment, the water temperature sensor 46 that detects the cooling water temperature is used to detect the engine temperature. However, the oil temperature sensor that detects the temperature of the engine oil is used alone or in combination with the water temperature sensor 46 to control the engine temperature. You may make it ask.

  [1] A multi-link in which a control link 25 is connected to one of a plurality of links 23 and 24 linking the piston 12 and the crank pin 22 of the crankshaft 11 with an electrically controlled throttle valve 41 that opens and closes the intake passage 16. Piston-crank mechanism 21 and an actuator 27 for changing / holding the position of the link support 26 of the control link 25, and the piston motion and the throttle valve that change according to the position of the link support 26 41 is a control device for a four-cycle reciprocating internal combustion engine that adjusts the intake air amount by controlling the throttle opening of 41, and in the transition period in which the throttle opening is changed according to the engine operating state, The piston motion is temporarily changed so as to cancel the torque fluctuation accompanying the change in the degree.

  With such a configuration, the change in the throttle opening is changed by temporarily changing the piston motion in a transition period in which the throttle opening is changed according to the engine operating state, for example, in an acceleration transition period from a low load. Therefore, the torque fluctuation due to the intake air amount, that is, the torque response delay due to the torque can be satisfactorily absorbed and offset, and the torque response performance can be improved.

  [2] The change in the intake air amount due to the change in the throttle opening is much less responsive than the change in the intake air amount due to the change in the piston motion. In the case of a setting where there is a region where the amount is changed and a region where the intake air amount is changed only by the throttle valve, the torque response will differ depending on the operating region. Specifically, the intake air amount is adjusted by the throttle valve. In the area where the intake air amount is adjusted, the responsiveness of the intake air amount in the transition period of acceleration / deceleration where the required torque changes is lower than in the region where the intake air amount is adjusted by the piston motion, and the passenger is more likely to feel strange. Therefore, the control of [1] is preferably performed in the acceleration transition period from the low load range to the medium load range in which the throttle opening is increased without substantially changing the piston motion in this way.

  The reason for not using piston motion for intake air amount control in the engine low to medium load range is that the intake stroke amount is already small in the engine low to medium load region, and if the intake stroke amount is further reduced, the compression ratio It is necessary to increase the compression top dead center position in order to suppress the decrease in the compression ratio as the intake stroke amount becomes smaller and the intake stroke amount becomes smaller. However, there is a limit.

  [3] As in the first embodiment, during the acceleration transition period, the length of the intake stroke directly related to the intake air amount, that is, the intake stroke amount, is temporarily increased, so that the intake amount due to the response delay is increased. It is possible to offset the shortage of

  [4] Further, as in the second embodiment, in the acceleration transition period, the manifold pressure downstream of the throttle valve 41 is estimated, and the piston motion is temporarily changed based on the pressure change. The response delay of the intake air amount due to the change in the throttle opening can be estimated with higher accuracy, and the torque response can be further improved.

  [5] As in the third embodiment, in the acceleration transition period, the throttle opening degree is set by setting the change amount of the piston motion in consideration of the change in the thermal efficiency accompanying the temporary change of the piston motion. It becomes possible to estimate the response delay of the intake air amount due to the change in the accuracy more accurately.

  [6] As in the fourth embodiment, in the acceleration transition period, the thermal efficiency in the acceleration transition period can be improved by temporarily increasing the compression top dead center position.

  [7] As in the fifth embodiment, during the acceleration transition period, the intake stroke efficiency during the transition is improved by temporarily shortening the crank angle of the intake stroke, and the actually generated torque is determined by the target torque. You can get closer.

  [8] As in the sixth embodiment, during the acceleration transition period, the crank angle of the intake stroke is temporarily lengthened, and the crank angle of the compression stroke is temporarily shortened so that the compression stroke is compressed. The turbulence in the cylinder can be strengthened, and the combustion can be made more stable.

The block diagram which shows an example of the control system of the reciprocating type internal combustion engine which concerns on this invention. The block diagram which shows an example of a multilink type piston-crank mechanism. The characteristic view which shows the example of 1 setting of the target position of the link support part with respect to a crank angle. The characteristic view which shows the piston motion in the setting of the link support part of FIG. The block diagram which shows typically the setting process of the target position of the link support part which concerns on 1st Example of this invention. The characteristic view which shows the relationship between an accelerator opening (APO) and required torque (tTe). The characteristic view which shows the relationship between the target intake stroke amount (A) and the target throttle opening (B) with respect to the required torque. The characteristic view which shows the relationship between intake stroke amount and an engine compression ratio. The flowchart which shows the flow of the calculation process of the target intake stroke amount which concerns on the said 1st Example. The time chart of the acceleration transition period from the low load area to the middle load area according to the first embodiment. The time chart of the acceleration transition period from the low load area to the middle load area according to the second embodiment of the present invention. The time chart of the acceleration transition period from the low load area to the middle load area according to the third embodiment of the present invention. The characteristic view which shows the relationship of the efficiency with respect to the amount of intake strokes concerning the said 3rd Example. The characteristic view which shows the relationship of the piston position with respect to the crank angle which concerns on 4th Example of this invention. The characteristic view which shows the relationship between the intake stroke amount and compression ratio which concern on the said 4th Example. The characteristic view which shows the relationship of the piston position with respect to the crank angle which concerns on 5th Example of this invention. The characteristic view which shows the relationship between the intake stroke amount deficiency value and the intake stroke angle according to the fifth embodiment. The characteristic view which shows the relationship of the piston position with respect to the crank angle which concerns on 6th Example of this invention. The characteristic view which shows the relationship between the manifold pressure which concerns on 6th Example, and an intake stroke angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Crankshaft 12 ... Piston 13 ... Cylinder 21 ... Double link type piston-crank mechanism 22 ... Crank pin 23 ... Lower link 24 ... Upper link 25 ... Control link 26 ... Link support part 27 ... Actuator 40 ... Control part

Claims (9)

An electronically controlled throttle valve that opens and closes the intake passage, a multi-link type piston-crank mechanism in which a control link is connected to one of a plurality of links that link a piston and a crank pin of a crankshaft, and link support of the control link An actuator for changing and holding the position of the part,
A control device for a four-cycle reciprocating internal combustion engine that adjusts an intake air amount by controlling a piston motion that changes according to a position of the link support and a throttle opening of the throttle valve,
A reciprocating internal combustion engine characterized by temporarily changing the piston motion so as to cancel out torque fluctuations associated with the change in the throttle opening during a transition period in which the throttle opening is changed in accordance with the engine operating state. Control device.   The reciprocating system according to claim 1, wherein the transition period includes an acceleration transition period from a low load range to a medium load range in which the throttle opening is increased without substantially changing the piston motion. Control device for internal combustion engine.   The reciprocating internal combustion engine control device according to claim 2, wherein the length of the intake stroke is temporarily increased during the acceleration transition period.   4. The internal combustion engine according to claim 2, wherein a manifold pressure downstream of the throttle valve is estimated during the acceleration transition period, and a piston motion is temporarily changed based on the pressure change. 5. Control device.   5. The control of a reciprocating internal combustion engine according to claim 4, wherein in the acceleration transition period, a change amount of the piston motion is set in consideration of a change in thermal efficiency due to a temporary change of the piston motion. apparatus.   The reciprocating internal combustion engine control device according to claim 2, wherein the compression top dead center position is temporarily increased during the acceleration transition period.   3. The control device for a reciprocating internal combustion engine according to claim 2, wherein the crank angle of the intake stroke is temporarily shortened during the acceleration transition period.   3. The control device for a reciprocating internal combustion engine according to claim 2, wherein, during the acceleration transition period, the crank angle of the intake stroke is temporarily increased and the crank angle of the compression stroke is temporarily shortened. An electronically controlled throttle valve that opens and closes the intake passage, a multi-link type piston-crank mechanism in which a control link is connected to one of a plurality of links that link a piston and a crank pin of a crankshaft, and link support of the control link And a reciprocating internal combustion engine control method comprising:
Adjust the intake air amount by controlling the piston motion that changes according to the position of the link support and the throttle opening of the throttle valve,
And the control method of the reciprocating type internal combustion engine characterized by temporarily changing the piston motion in a transition period in which the throttle opening is changed according to the engine operating state.

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