JP5910528B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine including an intake valve that opens and closes a cylinder.

  There is known an internal combustion engine that includes a variable valve mechanism that can change a phase at which an intake valve or an exhaust valve opens and closes. In a control device applied to such an internal combustion engine, the operation amount of the variable valve mechanism, for example, the number of rotations of the electric motor that operates the variable valve mechanism is detected, and based on the detected operation amount and the map. A control device that detects a phase at which an intake valve or an exhaust valve opens and closes is known (see Patent Document 1). In addition, there is Patent Document 2 as a prior art document related to the present invention.

JP 2007-198314 A JP 2007-263091 A

  As a valve operating mechanism for opening and closing an intake valve, a mechanism having a rocker arm and a lash adjuster that supports the rocker arm is known. As is well known, the lash adjuster operates by hydraulic pressure, and when the hydraulic pressure changes, the position of the fulcrum of the rocker arm changes and the phase of the intake valve changes. In the apparatus of Patent Document 1, in order to cope with the change in the phase of the intake valve by such a lash adjuster, it is necessary to prepare a plurality of maps according to the hydraulic pressure. When calculating the phase at which the intake valve opens and closes, it is necessary to switch and use these maps, which may take time when calculating the opening / closing phase.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an internal combustion engine that can easily detect whether or not an intake valve is closed and can accurately detect the closing timing.

  The control device of the present invention is the control device for an internal combustion engine provided with a rotational speed detection means for detecting the rotational speed of a crankshaft of the internal combustion engine or a rotating body that rotates together with the crankshaft when the internal combustion engine is started. Closed that determines that the intake valve of the cylinder of the internal combustion engine is closed when the time differential value obtained by differentiating the rotational speed detected by the detection means changes from a value larger than a predetermined threshold value to a value smaller than the threshold value. Valve determination means is provided (claim 1).

  In the control device of the present invention, it is determined whether or not the intake valve is closed based on the crankshaft or the rotational speed of the rotating body that rotates together with the crankshaft. Since the exhaust valve is also closed when the intake valve is closed, when the intake valve is closed, gas is trapped in the cylinder. Therefore, the rotation speed of the crankshaft changes abruptly. In the present invention, since it is determined whether or not the intake valve is closed based on the phenomenon that occurs when the intake valve is actually closed in this way, for example, even if a lash adjuster or the like is provided, the intake valve is closed. The time can be detected accurately. Further, since the rotation speed of the crankshaft can be detected by a sensor generally provided in the internal combustion engine, it can be easily detected whether or not the intake valve is closed.

  In one form of the control device of the present invention, the valve closing determination means is configured to take in the intake valve only for the cylinder in which the intake valve is first closed after the cranking of the internal combustion engine is started when the internal combustion engine is started. It may be determined whether or not is closed (Claim 2). If the rotation speed of the crankshaft increases to a certain extent, it becomes difficult to detect fluctuations in the rotation speed due to the intake valve closing. Further, the hydraulic pressure of the lash adjuster has already increased to an appropriate pressure at the time when the intake valve of the cylinder in which the intake valve is closed for the second time after the cranking starts is closed. Therefore, it is possible to avoid useless detection of the closing timing of the intake valve by making a determination only for the cylinder in which the intake valve is closed first.

  In one form of the control device of the present invention, the internal combustion engine is a spark ignition type internal combustion engine provided with an ignition plug, and the valve closing determining means is configured to start the cranking of the internal combustion engine after the ignition plug is started. It may be determined whether or not the intake valve of the cylinder of the internal combustion engine is closed during the period until ignition by is started. When ignition by the spark plug is started, the rotational speed fluctuation based on the explosion combustion of the fuel mixture becomes dominant. For this reason, it is difficult to detect fluctuations in the rotational speed of the crankshaft due to the closing of the intake valve after the start of ignition. In this embodiment, since determination is not performed during such a period, useless detection of the closing timing of the intake valve can be avoided.

  In one form of the control device of the present invention, the internal combustion engine may be a two-cylinder internal combustion engine. Generally, in a two-cylinder internal combustion engine, the pistons of both cylinders rise and fall at the same time, so it is easy to detect fluctuations in the rotational speed of the crankshaft due to the intake valve closing. Therefore, it is possible to accurately detect the closing timing of the intake valve.

  In one form of the control device of the present invention, the internal combustion engine includes an electric motor provided to drive the crankshaft, and a closing timing of the intake valve when the hydraulic pressure of the internal combustion engine is equal to or higher than a set pressure. When the hydraulic pressure from the oil pump is lower than the set pressure, a low hydraulic pressure state is reached in which the closing timing of the intake valve is a second crank angle earlier than the first crank angle. A lash adjuster that switches to a crank angle based on a valve closing timing at which the intake valve is determined to be closed by the valve closing determination means and a crank angle at the start of cranking of the internal combustion engine. Torque ratio calculation that calculates a torque ratio that is a ratio of a torque that is expected to be applied from the cylinder to the crankshaft when cranking is started from a predetermined reference torque And torque calculating means for calculating a torque expected to be applied from the cylinder to the crankshaft during cranking of the internal combustion engine based on the torque ratio calculated by the torque ratio calculating means, and the torque Control means for controlling the operation of the electric motor during cranking of the internal combustion engine based on the torque calculated by the calculating means, and the torque calculating means after starting cranking of the internal combustion engine, Switch the calculation method to calculate the torque between the transition period until the first expansion stroke after the cranking starts and the transition period after the cylinder starts the cranking stroke after the cranking starts. (Claim 5). As described above, in the present invention, it is determined whether or not the intake valve is closed based on a phenomenon that occurs when the intake valve is actually closed. According to this aspect, the torque that is expected to be applied from the cylinder to the crankshaft during cranking of the internal combustion engine is calculated based on the closing timing of the intake valve determined in this way. Can be increased. Since cranking of the internal combustion engine is performed based on the torque, vibration at the start of the internal combustion engine can be suppressed.

  As described above, according to the control device of the present invention, it is determined whether or not the intake valve is closed based on fluctuations in the rotational speed of the crankshaft caused by actually closing the intake valve. The valve closing timing can be accurately detected. Further, since the rotation speed of the crankshaft can be detected by a sensor generally provided in the internal combustion engine, it can be easily detected whether or not the intake valve is closed.

The figure which shows the principal part of the drive device of the hybrid vehicle to which the control apparatus which concerns on one form of this invention was applied. The figure which shows the cross section of # 1 cylinder of the internal combustion engine of FIG. The figure which shows schematically a part of valve operating mechanism provided in the internal combustion engine. The figure which shows a lash adjuster schematically. The figure which shows typically the cylinder of a compression stroke. The figure which shows typically the cylinder of an expansion stroke. The figure which shows the time change of the torque at the time of cranking in case the initial crank angle is 0 degree, the initial crank angle is 30 degrees, and the initial crank angle is 60 degrees. The figure which shows the time change of the torque at the time of cranking in the case where an initial crank angle is 90 degrees and an initial crank angle is 120 degrees. The figure which shows the time change of the torque at the time of cranking in the case of the crank angle which the exhaust valve of a cylinder with an initial crank angle of # 3 opens, and when the initial crank angle is 180 degrees. The figure which shows an example of the relationship between the pulsation torque of each cylinder in case an initial crank angle is a predetermined angle, and a crank angle. The figure which shows the relationship between a crank angle and V ((theta)) ( ^gamma ). The figure which shows the time change of the rotation speed of the crankshaft at the time of cranking, and the time change of the value which differentiated the rotation speed to the first-order time. The figure which shows an example of the actual pulsation torque of an internal combustion engine. The figure which shows an example of the relationship between an initial crank angle, the engine water temperature, and a threshold value. The block diagram which shows the method of calculating | requiring a valve closing crank angle. The flowchart which shows the valve closing crank angle detection routine which a vehicle control apparatus performs. The flowchart which shows the cranking control routine which a vehicle control apparatus performs. The block diagram which shows the method of calculating | requiring a valve closing crank angle based on the rotation speed of a motor generator. The figure which shows schematically the other internal combustion engine to which the control apparatus of this invention is applied.

  Hereinafter, an embodiment will be described by applying the present invention to a drive device of a hybrid vehicle. As shown in FIG. 1, the drive device 2 of the hybrid vehicle 1 includes an internal combustion engine (hereinafter abbreviated as “engine”) 10 </ b> A and a motor / generator 3. The engine 10 </ b> A and the motor / generator 3 are connected to the power split mechanism 4. The power split mechanism 4 is configured as a single pinion type planetary gear mechanism. The power split mechanism 4 is capable of rotating a sun gear S that is an external gear, a ring gear R that is an internal gear disposed coaxially with the sun gear S, and a pinion gear P that meshes with these gears S and R. And a carrier C that holds the periphery of the sun gear S so as to be able to revolve. The sun gear S is connected to the motor / generator 3 so as to rotate integrally therewith. The carrier C is connected to the crankshaft 10a of the engine 10A via the damper 5. The damper 5 is a well-known one that attenuates rotational fluctuations that occur between the engine 10 </ b> A and the power split mechanism 4. The ring gear R is connected to the output gear 6. The output gear 6 is connected to drive wheels through a reduction mechanism (not shown) so that power can be transmitted.

  The engine 10A is a spark ignition type four-cycle internal combustion engine mounted on a vehicle as a driving power source. The engine 10 </ b> A includes four cylinders 11. As shown in the figure, the cylinder numbers # 1 to # 4 are assigned to the cylinders from one end to the other end in the arrangement direction to distinguish them from each other. In this engine 10A, the explosion interval between the # 1 cylinder 11 and the # 3 cylinder 11 is shifted by 360 ° CA (meaning the crank angle), and the explosion timing of the # 4 cylinder 11 and the # 2 cylinder 11 is # 1. By shifting the cylinder 11 by 180 ° CA and 540 ° CA with reference to the explosion timing of the cylinder 11, explosions at equal intervals of 180 ° CA are realized. In this engine 10A, the explosion order is set so that explosion occurs in each cylinder 11 in the order of # 1, # 4, # 3, and # 2.

  FIG. 2 shows a schematic diagram of a cross section of the cylinder 11 of # 1. The other cylinders 11 have the same structure as the cylinder 11 of # 1. As shown in FIG. 2, a piston 12 is inserted into the cylinder 11 so as to reciprocate, and a combustion chamber 13 is formed in each cylinder 11 by the piston 12 and the wall surface of the cylinder 11. The piston 12 is connected to the crankshaft 10 a by a connecting rod 14 and a crank arm 15. Note that the phase of the piston 12 in each cylinder 11 is shifted by 180 ° in terms of crank angle so that the above-described equidistant explosion is realized. An intake port 16 and an exhaust port 17 are connected to the cylinder 11. The cylinder 11 is provided with an intake valve 18 for opening and closing the intake port 16 and an exhaust valve 19 for opening and closing the exhaust port 17. Further, the cylinder 11 is provided with a spark plug 20 for igniting the fuel mixture in the cylinder 11.

  The intake valve 18 and the exhaust valve 19 are driven to open and close by a valve mechanism 30 shown in FIG. In this figure, only the portion of the valve mechanism 30 that drives the intake valve 18 to open / close is shown, and the portion that drives the exhaust valve 19 to open / close is not shown. The valve operating mechanism 30 includes a cam shaft 31 for opening and closing the intake valve 18. An arrow A in the figure indicates the rotation direction of the cam shaft 31. A cam 32 is provided on the cam shaft 31 so as to be integrally rotatable. A rocker arm 33 is interposed between the cam 32 and the intake valve 18. One end of the rocker arm 33 is supported by a lash adjuster 34. The valve mechanism 30 includes a valve spring 35 that urges the intake valve 18 in the valve closing direction. The rocker arm 33 is provided such that the intermediate portion 33 a is in contact with the cam 32, one end portion 33 b is in contact with the intake valve 18, and the other end portion 33 c is in contact with the lash adjuster 34. The rocker arm 33 is provided so as to be swingable about the one end 33b.

  As shown in FIG. 4, the lash adjuster 34 has a hollow cylindrical body 37 that is open at one end. A plunger 38 is movably mounted on the body 37 such that a part thereof protrudes from the opening. A hydraulic chamber 39 is provided at the bottom of the body 37. Oil is supplied to the hydraulic chamber 39 from an oil pump (not shown) of the engine 10A. Since this oil pump is a known one that is driven by the crankshaft 10a, description thereof is omitted. When oil is supplied to the hydraulic chamber 39, the plunger 38 is pushed to hydraulic pressure. As a result, the tip of the plunger 38 protrudes as shown on the left side of FIG. Hereinafter, this state may be referred to as a normal state. In this case, the rocker arm 33 moves to the position indicated by the solid line in FIG. On the other hand, when the engine 10A stops, the oil pump also stops, so the hydraulic pressure in the hydraulic chamber 39 decreases. In this case, the plunger 38 is pushed toward the body 37 by the rocker arm 33 as shown on the right side of FIG. Therefore, the protrusion amount of the plunger 38 is reduced by the distance L compared to the normal state. Hereinafter, this state may be referred to as a low hydraulic pressure state. In this case, the rocker arm 33 moves to a position indicated by a broken line in FIG.

  When the rocker arm 33 is in the position indicated by the solid line, that is, when the lash adjuster 34 is in the normal state, the cam 32 moves away from the rocker arm 33 at a point Pc1 in FIG. On the other hand, when the rocker arm 33 is at the position indicated by the broken line, that is, when the lash adjuster 34 is in the low hydraulic pressure state, the cam 32 moves away from the rocker arm 33 at a point Pc2 in FIG. Therefore, the timing at which the intake valve 18 closes is earlier than when the lash adjuster 34 is in the normal state.

  As described above, the oil pump is stopped while the engine 10A is stopped. Therefore, the lash adjuster 34 is in a low hydraulic pressure state when cranking is started. In this case, the crank angle (valve closing crank angle) θIVC at which the intake valve 18 is closed becomes the crank angle θL. When cranking is started and the oil pump starts to move, oil is supplied to the hydraulic chamber 39, and the lash adjuster 34 is in a normal state during cranking. In this case, the valve closing crank angle θIVC becomes a crank angle θH that is slower than the crank angle θL. Thus, when the state of the lash adjuster 34 changes, the timing at which the intake valve 18 closes changes.

  The operations of the motor / generator 3 and the engine 10 </ b> A are controlled by the vehicle control device 40. The vehicle control device 40 is a computer unit including a microprocessor and peripheral devices such as RAM and ROM necessary for its operation. The vehicle control device 40 controls various control objects such as the motor / generator 3 and the engine 10A according to a predetermined control program, thereby controlling the vehicle 1. Various sensors for acquiring the state of the vehicle 1 are connected to the vehicle control device 40. For example, a crank angle sensor 41 and a water temperature sensor 42 as rotation speed detecting means are connected to the vehicle control device 40. The crank angle sensor 41 outputs a signal corresponding to the angle (crank angle) of the crankshaft 10a. The water temperature sensor 42 outputs a signal corresponding to the temperature (water temperature) of the cooling water of the engine 10A. In addition to this, various sensors are connected to the vehicle control device 40, but these are not shown.

  When the engine 10A is stopped and the start of the engine 10A is requested, the vehicle control device 40 performs cranking for driving the crankshaft 10a by the motor / generator 3 and thereby starts the engine 10A. Therefore, the motor / generator 3 corresponds to the electric motor of the present invention. At this time, the vehicle control device 40 estimates torque (pulsation torque) applied to the crankshaft 10a from each of the cylinders # 1 to # 4 at the time of cranking, and uses torque and cranking to cancel the pulsation torque. The total torque required is output from the motor / generator 3 to crank the engine 10A.

A method for calculating the pulsation torque will be described with reference to FIGS. When cranking is performed as is well known, torque is applied to the crankshaft 10a from each of the cylinder 11 in the compression stroke and the cylinder 11 in the expansion stroke. As shown in FIG. 5, from the cylinder 11 in the compression stroke, when the direction in which the crankshaft 10a should be rotated at the time of cranking is the forward direction (clockwise in FIG. 5), the direction opposite to the forward direction ( Torque τ _e (θ) for turning the crankshaft 10a is applied counterclockwise in FIG. On the other hand, as shown in FIG. 6, torque τ _e (θ) for rotating the crankshaft 10a in the positive direction is applied from the cylinder 11 in the expansion stroke. The torque applied to the crankshaft 10a from the cylinder 11 in the compression stroke can be expressed by the following equation (1). The torque applied from the cylinder 11 in the expansion stroke to the crankshaft 10a can be expressed by the following equation (2).

Incidentally, FIG. 5 or as shown in FIG. 6 p (theta) in each formula the pressure in the cylinder 11 (hereinafter sometimes referred to as in-cylinder pressure.) Indicates, p _a denotes the atmospheric pressure. Further, S _p represents the cross-sectional area of the piston 12, r denotes the length of the crank arm 15. Φ indicates the angle formed by the center line CL of the cylinder 11 and the connecting rod 14, and θ indicates the crank angle.

As is clear from these equations (1) and (2), the torque exerted on the crankshaft by one cylinder 11 at a certain crank angle θ is affected by the in-cylinder pressure p (θ). However, this in-cylinder pressure p (θ) is confined in the cylinder 11 even if the crank angle θ is the same, that is, the volume in the cylinder 11 (hereinafter also referred to as the in-cylinder volume) is the same. It changes according to the amount of gaseous material. The ratio of the torque when the amount of gas material is n1 and the torque when the amount of gas substance is n2 (hereinafter referred to as torque ratio) k _t (θ) is the above equation (1) or (2). And can be expressed by equation (3).

In the equation (3), the torque τe (θ) and the in-cylinder pressure p (θ) when the substance amount is n1 are given a subscript 1, and the torque τe (θ) and the in-cylinder pressure p when the substance amount is n2. Subscript 2 is added to (θ). As is clear from the equation (3), if the torque when a gas having a predetermined substance amount is in the cylinder 11 is obtained in advance, a gas having another substance amount can be obtained by using the torque ratio k _t (θ). Can be estimated.

However, the torque ratio k _t (θ) cannot be calculated unless the value of the in-cylinder pressure p (θ) is known in the expression (3). Therefore, a method for expressing the torque ratio k _t (θ) using the in-cylinder volume V (θ) will be described. V (θ) represents the in-cylinder volume at the crank angle θ. As is well known, the gas pressure p and the volume V have the relationship shown in the following equation (4). In the equation (4), γ is a specific heat ratio.

Thus for pV ^gamma it is constant, the relationship between pressure and cylinder volume at the time of cranking in the case the amount of substance of the gas in the cylinder 11 is n1 can be expressed by the following equation (5). Further, the relationship between the cranking pressure and the in-cylinder volume when the gas substance amount in the cylinder 11 is n2 can be expressed by the following equation (6).

In these formulas, θ _ini represents a crank angle when cranking is started (hereinafter sometimes referred to as an initial crank angle), and V (θ) is a cylinder volume when the crank angle is θ. Is shown. Similarly to the above formula (3), the subscript 1 is attached to the pressure and the in-cylinder volume when the amount of substance is n1, and the subscript 2 is attached to the pressure and the in-cylinder volume when the amount of substance is n2. Then, the following equation (7) is derived from these equations (3), (5), and (6). However, equation (7) uses the relationship shown in equation (8).

From this equation (7), the torque ratio k _t (θ) can be calculated if the cylinder volume V (θ _ini ) at the start of cranking and the cylinder volume V (θ) when the crank angle is θ are known. I understand.

Next, a method for calculating the pulsation torque using this torque ratio k _t (θ) will be described. FIGS. 7 to 9 show an example of the change over time of the torque acting on the crankshaft 10 a during cranking for each cylinder 11. However, in these drawings, the lash adjuster 34 is in a low hydraulic pressure state at the start of cranking, and is switched to a normal state during cranking. As described above, when the hydraulic pressure is low, the lash adjuster 34 is in a low hydraulic pressure state, and the valve closing crank angle θIVC becomes the crank angle θL. Therefore, the closing crank angle θIVC of the intake valve 18 of the # 2 cylinder 11 that first closes the intake valve 18 after cranking starts becomes the crank angle θL, and the other cylinders after which the intake valve 18 closes. 11 has a closed crank angle θIVC equal to the crank angle θH.

  In these drawings, the torque that rotates the crankshaft 10a in the positive direction is shown as positive (plus) torque, and the torque that rotates the crankshaft 10a in the reverse direction is shown as negative (minus) torque. 7 to FIG. 9 show the time change in torque when the # 3 cylinder 11 starts the engine 10A stopped in the expansion stroke state. The lower diagram of FIG. 9 shows a change in torque over time when the engine 10A stopped in a state in which the # 2 cylinder 11 is in the expansion stroke is started. In these examples, the crank angle when the piston 12 of the cylinder 11 of # 3 is at the top dead center (TDC) of the expansion stroke is set to 0 °.

  In these drawings, the number of times that any one of the pistons 12 of the four cylinders 11 has passed the top dead center (TDC) since cranking is started (hereinafter also referred to as the TDC number) is referred to as TDC (n. ). The number of TDCs becomes “1” when, for example, cranking is started and the piston 12 of the cylinder 11 of # 3 first passes the top dead center. Since the engine 10A is a four-cylinder four-cycle engine, the number of TDC increases by 1 every time the crank angle is 180 ° thereafter. The value of the number of TDCs is stored in the RAM of the vehicle control device 40 during cranking. When the cranking is completed, it is reset to zero. In these figures, the case where the engine 10A stopped in a state in which the # 3 cylinder 11 is in the expansion stroke is started. The engine 10A is a four-cylinder internal combustion engine. Therefore, TDC (0) is obtained when the crank angle θ is 0 °. When the crank angle θ is 180 °, TDC (1) is obtained, and when the crank angle θ is 360 °, TDC (2) is obtained.

  FIG. 7 shows changes in torque over time when the initial crank angle is 0 °, when the initial crank angle is 30 °, and when the initial crank angle is 60 °. FIG. 8 shows changes in torque over time when the initial crank angle is 90 ° and the initial crank angle is 120 °. FIG. 9 shows changes in torque over time when the initial crank angle is the crank angle θEVO where the exhaust valve 19 of the cylinder 11 of # 3 opens and when the initial crank angle is 180 °. As shown in FIGS. 7 and 8, even when the lash adjuster 34 is in a low hydraulic pressure state at the start of cranking, the intake valve 18 of the # 1 cylinder 11 that becomes the second compression stroke at the time of cranking is at the crank angle θH. Close the valve. Therefore, the influence of the lash adjuster 34 affects only the cylinder 11 that is initially in the compression stroke at the time of cranking, that is, the cylinder 11 of # 2.

  First, a method for calculating the pulsation torque when the crank angle θ is between TDC (0) and TDC (1) will be described. As is apparent from FIGS. 7 to 9, when the crank angle θ is within this range, the total torque of the torque of the cylinder # 11 and the torque of the cylinder # 2 acts on the crankshaft 10a. Further, as is clear from these drawings, these torques change according to the initial crank angle θini. When the initial crank angle θini is in the range of 0 ° ≦ θini <θIVC, the torque of the cylinder 11 of # 3 changes according to the initial crank angle θini. On the other hand, when the initial crank angle θini is in the range of θIVC ≦ θini <(720 / α) °, the torque of the cylinder 11 of # 2 also changes according to the initial crank angle θini. “Α” is the number of cylinders of the engine 10A. Therefore, (720 / α) ° is 180 °. Therefore, the calculation method of the pulsation torque is switched between the case where the initial crank angle θini is 0 ° ≦ θini <θIVC and the case where the initial crank angle θini is θIVC ≦ θini <(720 / α) °.

The in-cylinder volume V (θ _ini ) at the start of cranking of each cylinder 11 varies according to the initial crank angle θini. As is well known, when the engine 10A is stopped, even if the intake valve 18 and the exhaust valve 19 are closed, gas escapes from the cylinder 11 and the in-cylinder pressure becomes almost atmospheric pressure. In this case, when the cylinder volume V (θ _ini ) at the start of cranking changes, the amount of substance in the cylinder 11 changes at that time. Therefore, as shown in FIGS. 7 to 9, the torque from each cylinder 11 changes according to the initial crank angle θini. If the torque ratio is used as shown in the above equation (3), the torque when the substance amount in the cylinder 11 is n2 can be calculated from the torque when the substance amount in the cylinder 11 is n1. Therefore, the relationship between the pulsation torque and the crank angle when the initial crank angle θini is 0 ° is obtained in advance by experiments or numerical calculations, and stored in the ROM of the vehicle control device 40 as a map.

FIG. 10 shows an example of this map. In this figure, τ _e0 (θ) is the cylinder 11 (# 3 of # 3) that first becomes the expansion stroke at the time of cranking in the range of TDC (0) to TDC (1) when the initial crank angle θini is 0 °. The relationship between the pulsation torque of the cylinder 11) and the crank angle is shown. Further, τ _e1 (θ) is the cylinder 11 (# 2 of # 2) that becomes the second expansion stroke at the time of cranking in the range of TDC (0) to TDC (1) when the initial crank angle θini is the crank angle θL. The relationship between the pulsation torque of the cylinder 11) and the crank angle is shown. Then, τ _e2 (θ) is the cylinder 11 (# 1 cylinder) that is in the third expansion stroke during cranking in the range of TDC (1) to TDC (2) when the initial crank angle θini is 0 °. 11) shows the relationship between the crank angle and the torque obtained by synthesizing the pulsating torque of the cylinder 11 (# 4 cylinder 11) which is the fourth expansion stroke during cranking and the pulsating torque of 11).

First, a method for calculating the pulsation torque when the initial crank angle θini is 0 ° ≦ θini <θIVC will be described. As described above, in this embodiment, the valve closing crank angle θIVC of the intake valve 18 of the cylinder # 2 changes in accordance with the hydraulic pressure. Therefore, the pulsation torque is calculated in consideration of the influence of the valve closing crank angle θIVC. Therefore, the pulsation torque when the initial crank angle θini is in the range of 0 ° ≦ θini <θIVC is calculated using the following equation (9). In this equation, kt_ _{# 3} (θini, θ) is calculated by equation (10), and kt_ _{# 2} (θ) is calculated by equation (11). However, when kt_ _{# 3} (θini, θ) is less than 0 as shown in the equation (12), 0 is substituted into kt_ _{# 3} (θini, θ). Further, as shown in the equation (13), when _{kt_ # 2} (θ) is less than 0, 0 is substituted into _{kt_ # 2} (θ).

Note that V (θ) ^{γ in the} equations (10) and (11) is obtained by previously obtaining the relationship shown in FIG. 11 through experiments, numerical calculations, and the like and stored in the ROM of the vehicle control device 40 as a map. And the crank angle θ may be calculated.

Next, a method for calculating the pulsation torque when the initial crank angle θini is θIVC ≦ θini <(720 / α) ° will be described. In this case, the pulsation torque is calculated using the following equation (14). In this equation, kt_ _{# 3} (θini, θ) is calculated by equation (15), and kt_ _{# 2} (θini, θ) is calculated by equation (16). However, when kt_ _{# 3} (θini, θ) is less than 0 as shown in the equation (17), 0 is substituted into kt_ _{# 3} (θini, θ). Further, as shown in the equation (18), when kt_ _{# 2} (θini, θ) is less than 0, 0 is substituted into kt_ _{# 2} (θini, θ).

Next, a method for calculating the pulsation torque when the crank angle θ is between TDC (1) and TDC (2) will be described. When the crank angle θ is within this range, the torque obtained by adding the torque of the # 2 cylinder 11 and the torque of the # 1 cylinder 11 acts on the crankshaft 10a. The torque of the # 2 cylinder 11 is a torque generated when the gas confined in the # 2 cylinder 11 expands when the crank angle θ is the valve closing crank angle θIVC. On the other hand, the torque of the # 1 cylinder 11 is a torque for compressing the gas confined in the # 1 cylinder 11 when the intake valve 18 of the # 1 cylinder 11 is closed. Therefore, when calculating the pulsation torque when the crank angle θ is between TDC (1) and TDC (2), the initial crank angle θini is 0 ° ≦ θini <θIVC, and the initial crank angle θini is θIVC ≦ θini. The calculation method is switched depending on <(720 / α) °. When the initial crank angle θini is 0 ° ≦ θini <θIVC, the pulsation torque is calculated using the following equation (19). In this equation, _{kt_ # 2p} (θ) is calculated by equation (20), _{kt_ # 2m} (θ) is calculated by equation (21), and _{kt_ # 1} (θ) is (22). ). However, when _{kt_ # 2p} (θ) is less than 0 as shown in the equation (23), 0 is substituted into _{kt_ # 2p} (θ). Also, as shown in the equation (24), when _{kt_ # 2m} (θ) is less than 0, 0 is substituted into _{kt_ # 2m} (θ). When k _{t — # 1} (θ) is less than 0 as shown in equation (25), 0 is substituted into k _{t — # 1} (θ).

On the other hand, when the initial crank angle θini is θIVC ≦ θini <(720 / α) °, the pulsation torque is calculated using the following equation (26). In this equation, k _{t — # 2p} (θini, θ) is calculated by equation (27), k _{t — # 2m} (θini, θ) is calculated by equation (28), and k _{t — # 1} (θ ) Is calculated by equation (29). However, when kt_ _{# 2p} (θini, θ) is less than 0 as shown in the equation (30), 0 is substituted into kt_ _{# 2p} (θini, θ). Also, as shown in the equation (31), when kt_ _{# 2m} (θini, θ) is less than 0, 0 is substituted into kt_ _{# 2m} (θini, θ). When k _{t — # 1} (θ) is less than 0 as shown in equation (32), 0 is substituted into k _{t — # 1} (θ).

  A method for calculating the pulsation torque when the crank angle θ is after TDC (2) will be described. As is clear from TDC (2) to TDC (3) in FIGS. 7 to 9, after TDC (2), the torque of each cylinder 11 does not change according to the initial crank angle θini. In the period from TDC (n) to TDC (n + 1) after TDC (2), the torque of the cylinder 11 in the expansion stroke (the cylinder 11 of # 1 in the examples of FIGS. 7 to 9) and the cylinder 11 ( In the examples of FIGS. 7 to 9, the torque obtained by adding the torques of the # 4 cylinder 11) acts on the crankshaft 10a. In this case, the pulsation torque can be calculated by the following equation (33).

In this pulsation torque calculation method, an equation used for calculation is first selected from Equations (9) to (33) based on the number of TDCs and the initial crank angle θini. Next, τ _e0 (θ), τ _e1 (θ), τ _e2 (θ), and V (θ) ^γ are calculated based on the maps of FIGS. 10 and 11 and the current crank angle θ. Thereafter, the calculated τ _e0 (θ), τ _e1 (θ), τ _e2 (θ), and V (θ) ^γ and the valve closing crank angle θIVC may be substituted into the selected formula to calculate the pulsation torque.

  However, as described above, after cranking starts, oil is supplied to the lash adjuster 34, and the valve closing crank angle θIVC of the intake valve 18 changes. Therefore, the vehicle control device 40 calculates the valve closing crank angle θIVC based on the rotation speed of the crankshaft 10a during cranking.

  The following equation (34) shows the relationship between the pulsation torque and the rotational speed of the engine 10A. In this equation, Ie represents the rotational inertia of the engine 10A, and Ce represents the damping coefficient of the engine 10A. Further, τe represents the pulsating torque of the engine 10A, and τdmp represents the load torque of the damper 5. Θ represents the crank angle.

  As is apparent from the equation (34), it can be seen that when the intake valve 18 is closed and the pulsation torque of the engine 10A fluctuates, the influence appears in the rotational speed of the engine 10A and the load torque τdmp of the damper 5. Therefore, the valve closing crank angle θIVC can be detected based on the value of the crankshaft 10a detected by the crank angle sensor 41 when the crank angle θ is between the crank angle θL and the crank angle θH.

  This will be specifically described with reference to FIG. The intake valve 18 is closed during the intake stroke. In the intake stroke, the exhaust valve 19 is closed. Therefore, when the intake valve 18 is closed, gas is trapped in the cylinder 11. Therefore, when the intake valve 18 is closed, the load applied to the crankshaft 10a from the cylinder 11 in which the intake valve 18 is closed increases, and the rotational speed Ne of the crankshaft 10a changes greatly. The upper part of FIG. 12 shows the time change of the rotational speed Ne of the crankshaft 10a at the time of cranking. Further, the lower part of the figure shows a time change of a value obtained by differentiating the rotational speed Ne into the first order time (hereinafter sometimes referred to as a time differential value) ΔNe. In the example shown in this figure, the intake valve 18 is closed at time T1. Therefore, the rotational speed of the crankshaft 10a temporarily decreases at this time T1. Further, the time differential value ΔNe changes from a positive value to a negative value at the time T1.

  Therefore, the threshold value dNe_th is set as shown in this figure, the crank angle θ is between the crank angle θL and the crank angle θH, and the time differential value ΔNe changes from a value larger than the threshold value dNe_th to a value smaller than the threshold value dNe_th. In this case, it can be determined that the intake valve 18 is closed. The crank angle θ at the time T1 can be determined as the valve closing crank angle θIVC.

  FIG. 13 shows an example of pulsation torque detected by actually attaching a sensor to the engine 10A. As is clear from this figure and FIGS. 7 to 9, the pulsation torque changes according to the initial crank angle θini. Further, as apparent from the equation (34), the rotational speed Ne of the crankshaft 10a is affected by the friction of the engine 10A. As is well known, the lower the temperature, the greater the viscosity of the oil. Therefore, the friction of the engine 10A increases as the temperature of the engine 10A decreases. Therefore, the above-described threshold value dNe_th needs to be set according to the initial crank angle θini and the temperature of the engine 10A (for example, the coolant temperature or the oil temperature). Therefore, the relationship among the initial crank angle θini, the water temperature of the engine 10A, and the threshold value dNe_th is obtained in advance by experiments, numerical calculations, etc., and stored as a map in the ROM of the vehicle control device 40, and the threshold value dNe_th is determined based on the map. Set. FIG. 14 shows an example of this map. As shown in this figure, the threshold value dNe_th is basically increased as the water temperature of the engine 10A is higher and the initial crank angle θini is larger.

  The valve closing crank angle θIVC obtained in this way is used only during the period of TDC (0) to TDC (1) in which the state of the lash adjuster 34 is changing. That is, in the example shown in FIGS. 7 to 9, it is used only for the cylinder 11 of # 2. After TDC (1), since the lash adjuster 34 is switched to the normal state, the crank angle θH is used as the valve closing crank angle θIVC.

  FIG. 15 is a block diagram illustrating a method for obtaining the valve closing crank angle θIVC. As shown in this figure, the threshold value setting unit 50 receives the initial crank angle θini and the water temperature of the engine 10A, and outputs the threshold value dNe_th. Then, the threshold value dNe_th and the crank angle θ are input to the valve closing determination unit 51, where the valve closing crank angle θIVC is calculated.

  FIG. 16 shows a valve closing crank angle detection routine executed by the vehicle control device 40 in order to detect the valve closing crank angle θIVC in this way. Note that this routine is repeatedly executed at a predetermined cycle from the start of cranking of the engine 10A until the ignition of the fuel mixture by the spark plug 20 is started. Further, this routine is executed only for the cylinder 11 in which the intake valve 18 is first closed after the cranking of the engine 10A is started, specifically, for the cylinder 11 # 2 in the example shown in FIGS. The

  In this routine, the vehicle control device 40 first acquires the state of the engine 10A in step S11. As the state of the engine 10A, for example, the crank angle and the water temperature of the engine 10A are acquired. In this process, the rotation speed of the crankshaft 10a is acquired based on the crank angle. Further, in this process, the initial crank angle θini is acquired. This initial crank angle is a crank angle when the engine 10A is stopped. For this reason, the initial crank angle may be acquired based on the signal output last from the crank angle sensor 41 when the engine 10A is stopped, for example. In this process, other various information related to the state of the engine 10A is acquired.

  In the next step S12, the vehicle control device 40 determines whether or not it is within the period of TDC (0) to TDC (1). If it is determined that the period is outside the period of TDC (0) to TDC (1), the process proceeds to step S13, and the vehicle control device 40 sets the crank angle θH to the valve closing crank angle θIVC. Thereafter, the current control routine is terminated. In this case, the valve closing crank angle θIVC becomes the crank angle θH.

  On the other hand, if it is determined that the time is within the period of TDC (0) to TDC (1), the process proceeds to step S14, and the vehicle control device 40 sets the crank angle θL to the valve closing crank angle θIVC. In subsequent step S15, the vehicle control device 40 sets a threshold value dNe_th based on the initial crank angle θini and the water temperature of the engine 10A. Note that the threshold value dNe_th may be set by the setting method described above.

  In the next step S16, the vehicle control device 40 calculates a time differential value ΔNe of the rotational speed Ne of the crankshaft 10a. The following formula (35) is a formula for calculating the time differential value ΔNe. Note that Ts in this equation is a sampling time for the rotational speed Ne. K is a number for distinguishing the sampling time of the rotational speed Ne, and a natural number is entered (k = 1, 2, 3,...).

  In subsequent step S17, the vehicle control device 40 determines whether the time differential value ΔNe is less than the threshold value dNe_th and whether the crank angle θ is greater than the crank angle θL and less than or equal to the crank angle θH. If it is determined that the time differential value ΔNe is equal to or greater than the threshold value dNe_th, the crank angle θ is equal to or less than the crank angle θL, or the crank angle θ is greater than the crank angle θH, the current routine is terminated. In this case, the valve closing crank angle θIVC becomes the crank angle θL.

  On the other hand, when it is determined that the time differential value ΔNe is less than the threshold value dNe_th and the crank angle θ is greater than the crank angle θL and equal to or less than the crank angle θH, the process proceeds to step S18, and the vehicle control device 40 determines the crank angle θ at that time. The valve closing crank angle θIVC is set. Thereafter, the current control routine is terminated.

  FIG. 17 shows a cranking control routine executed by the vehicle control device 40 to crank the engine 10A. This control routine is repeatedly executed at a predetermined cycle regardless of whether the engine 10A is stopped or operating. In this control routine, the same processes as those in the routine shown in FIG.

  In this control routine, the vehicle control device 40 first acquires the state of the engine 10A in step S11. In the next step S21, the vehicle control device 40 determines whether or not a predetermined cranking condition is satisfied. This cranking condition is determined to be satisfied, for example, when the engine 10A is requested to start or when cranking is currently being performed. If it is determined that the cranking condition is not satisfied, the current control routine is terminated.

  On the other hand, if it is determined that the cranking condition is satisfied, the process proceeds to step S22, and the vehicle control device 40 counts the number of TDCs. As described above, the number of TDCs is reset to 0 when cranking is completed. In subsequent step S23, the vehicle control device 40 acquires the valve closing crank angle θIVC. As the valve closing crank angle θIVC, a value detected by the routine of FIG. 16 may be acquired.

  In the next step S24, the vehicle control device 40 calculates a pulsating torque. The pulsation torque may be calculated by the calculation method described above. In subsequent step S25, the vehicle control device 40 calculates cranking torque. The cranking torque includes a base torque for increasing the rotational speed of the engine 10A to a predetermined rotational speed that can supply fuel into each cylinder 11 and ignite the fuel mixture, and a calculated pulsating torque. Based on the above. At this time, the cranking torque is calculated so that the pulsating torque is offset. For example, when the pulsating torque rotates the crankshaft 10a in the reverse direction, a value obtained by adding the pulsating torque to the base torque is calculated as the cranking torque. On the other hand, when the pulsating torque rotates the crankshaft 10a in the positive direction, a value obtained by subtracting the pulsating torque from the base torque is calculated as the cranking torque.

  In the next step S26, the vehicle control device 40 executes MG control. In this MG control, the motor / generator 3 is controlled so that the calculated cranking torque is output from the motor / generator 3 and the engine 10A is cranked. Thereafter, the current control routine is terminated.

  As described above, according to the control device of the present invention, it is determined whether or not the intake valve 18 is closed based on the rotational speed of the crankshaft 10a. In this case, it is determined whether or not the intake valve 18 is closed based on a phenomenon that occurs when the intake valve 18 is actually closed. Therefore, even when the lash adjuster 34 is provided, the closing timing of the intake valve 18 is determined. It can be detected with high accuracy. Further, since the rotational speed Ne of the crankshaft 10a can be detected by a crank angle sensor 41 generally provided in an internal combustion engine, it can be easily detected whether or not the intake valve 18 is closed.

  The detection of the valve closing crank angle θIVC is performed only for the cylinder 11 in which the intake valve 18 is first closed after the cranking of the engine 10A is started. As described above, when the intake valve 18 is closed for the second time, the lash adjuster 34 is already in the normal state. Further, when the rotation speed of the crankshaft 10a is increased to a certain level, it is difficult to detect a fluctuation in the rotation speed due to the intake valve 18 being closed. Therefore, useless detection of the valve closing crank angle θIVC can be avoided by performing the operation only on the cylinder 11.

  Furthermore, the valve closing crankshaft θIVC is detected only during the period from the start of cranking of the engine 10A until the ignition of the fuel mixture by the spark plug 20 is started. When ignition by the spark plug 20 is started, the rotational speed fluctuation based on the explosive combustion of the fuel mixture becomes dominant. In the above-described embodiment, since the detection of the valve closing crank angle θIVC is not performed during such a period, useless detection of the valve closing crank angle θIVC can be avoided.

  In the control device of the present invention, since the pulsation torque is calculated based on the valve closing crank angle θIVC detected in this way, it is possible to improve the estimation accuracy of the pulsation torque. And since cranking of engine 10A is performed based on the pulsation torque, vibration at the time of starting of engine 10A can be suppressed.

  In the above description, the case where the # 3 cylinder 11 is stopped in the state of the expansion stroke, that is, the case where the cylinder 11 which becomes the expansion stroke first at the time of cranking is the # 3 cylinder 11 has been described as an example. Even when the other cylinders 11 are stopped in the expansion stroke, the pulsating torque calculation method described above can be applied. In this case, the cylinder 11 of # 3 and the cylinder 11 of # 2 in the above description may be replaced with the cylinder 11 that is first in the expansion stroke and the cylinder 11 that is next in the expansion stroke at the time of cranking.

  In addition, by performing step S17 of FIG. 16, the vehicle control apparatus 40 functions as the valve closing determination means of the present invention. The vehicle control device 40 functions as the control means of the present invention by executing steps S25 and S26 of FIG. By executing step S24 of FIG. 17, the vehicle control device 40 functions as a torque ratio calculation unit and a torque calculation unit of the present invention. As shown in FIGS. 7 to 9, the period from TDC (0) to TDC (2) corresponds to the transition period of the present invention. The crank angle θH corresponds to the first crank angle of the present invention, and the crank angle θL corresponds to the second crank angle of the present invention.

  In the above description, it is determined whether or not the intake valve 18 is closed based on the rotational speed Ne of the crankshaft 10a. However, the rotational speed used for this determination is not limited to the rotational speed Ne of the crankshaft 10a. For example, it may be determined whether the intake valve 18 is closed based on the rotational speed of the motor / generator 3 during cranking. The following equation (36) shows the relationship between the torque of the motor / generator 3 and the rotation angle θg of the motor / generator 3. In this equation, Ig represents the rotational inertia of the motor / generator 3, and Cg represents the damping coefficient of the motor / generator 3. Also, τg represents the torque of the motor / generator 3, and i 1 represents the reduction ratio in the power split mechanism 4.

  As is apparent from the equation (36), the fluctuation of the load torque of the damper 5 also affects the rotational speed dθg / dt of the motor / generator 3. The variation in the load torque of the damper 5 is affected by the variation in the pulsation torque of the engine 10A. Therefore, it can be determined whether the intake valve 18 is closed based on the rotational speed of the motor / generator 3. The torque τg of the motor / generator 3 is set so that the value does not change suddenly during the period between the crank angle θL and the crank angle θH, which is the timing at which the intake valve 18 is closed. Therefore, the influence on the rotational speed dθg / dt of the motor / generator 3 is almost negligible. When determining that the intake valve 18 is closed based on the rotational speed of the motor / generator 3, the time differential value of the rotational speed of the motor / generator 3 is obtained by the following equation (37). Note that Ts in this equation is a sampling time of dθg / dt. k is the same as in equation (35).

  In this method, the crank angle θ is between the crank angle θL and the crank angle θH, and the time differential value Δdθg / dt is a predetermined threshold value d (dθg), as in the case of using the rotation speed of the crankshaft 10a. / Dt) _th, it can be determined that the intake valve 18 is closed. The crank angle θ at this time can be determined as the valve closing crank angle θIVC. The threshold value d (dθg / dt) _th is also affected by the initial crank angle θini and the water temperature of the engine 10A. Therefore, even in this case, the relationship between the initial crank angle θini, the water temperature of the engine 10A, and the threshold value d (dθg / dt) _th is obtained in advance by experiments, numerical calculations, etc., and stored as a map in the ROM of the vehicle control device 40. The threshold value d (dθg / dt) _th is set based on the map. As this map, a map obtained by replacing the threshold value dNe_th in the map of FIG. 14 with a threshold value d (dθg / dt) _th is used. Therefore, the threshold value d (dθg / dt) _th basically increases as the water temperature of the engine 10A is higher and the initial crank angle θini is larger.

  FIG. 18 is a block diagram showing a method for obtaining the valve closing crank angle θIVC based on the rotational speed of the motor / generator 3. As shown in this figure, the threshold value setting unit 60 receives the initial crank angle θini and the water temperature of the engine 10A, and outputs a threshold value d (dθg / dt) _th. Then, the threshold value d (dθg / dt) _th, the crank angle θ, and the rotation angle θg of the motor / generator 3 are input to the valve closing determination unit 61. Then, the valve closing crank angle θIVC determined by the above-described determination method is calculated. Note that the rotor shaft and the rotor of the motor / generator 3 correspond to the rotating body of the present invention by obtaining the valve closing crank angle θIVC in this way.

  The internal combustion engine to which the present invention is applied is not limited to an internal combustion engine mounted on a hybrid vehicle and cranked by a motor / generator. For example, the present invention may be applied to the engine 10B shown in FIG. As shown in this figure, the engine 10B is provided with a generator 70 and a starter 71 for cranking the engine 10B. A belt 72 is wound around the generator 70 and the crankshaft 10a. Therefore, the generator 70 is driven by the crankshaft 10a. The following equation (38) shows the relationship between the pulsation torque and the rotational speed of the engine 10B. In this equation, Ie represents the rotational inertia of the engine 10B, and Ce represents the damping coefficient of the engine 10B. Further, τe represents the pulsating torque of the engine 10B, and τt represents the torque applied to the crankshaft 10a. Θ represents the crank angle.

  As is apparent from this equation, even in this engine 10B, it is possible to determine whether or not the intake valve 18 is closed based on the rotational speed Ne of the crankshaft 10a by using the same method as in the above-described embodiment.

  In the engine 10B, it may be determined whether the intake valve 18 is closed based on the rotation angle of the generator 70 or the starter 71. The following equation (39) shows the relationship between the rotation angle θg of the generator 70 or starter 71 and the torque τg of the generator 70 or starter 71. In this equation, Ig represents the rotational inertia of the generator 70 or starter 71, and Cg represents the attenuation coefficient of the generator 70 or starter 71. Also, τg represents the torque of the generator 70 or starter 71, and i2 represents the reduction ratio between the generator 70 and the crankshaft 10a or the reduction ratio between the starter 71 and the crankshaft 10a.

  As is clear from this equation, the rotation angle of the generator 70 or starter 71 can be used instead of the rotation angle of the motor / generator 3 of the above-described form, and the intake valve 18 can be closed based on these rotation angles. It can be determined whether or not. In addition, by calculating | requiring valve closing crank angle (theta) IVC in this way, the rotating shaft of the generator 70 or the output shaft of the starter 71 corresponds to the rotary body of this invention.

  The present invention may be applied to a two-cylinder internal combustion engine. In an internal combustion engine having three or more cylinders, when the piston is rising in any one cylinder, the piston is falling in the other cylinder. Therefore, even if the intake valve of any one of the cylinders closes and the rotational speed fluctuation occurs in the crankshaft, the rotational speed fluctuation may be suppressed by torque applied from the other cylinders to the crankshaft. Generally, in a two-cylinder internal combustion engine, the pistons of both cylinders rise and fall at the same time, so it is easy to detect fluctuations in the rotational speed of the crankshaft due to the intake valve closing. Therefore, the detection accuracy of the intake valve closing timing can be further improved.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, the detected valve closing timing of the intake valve may be used for various controls performed when the internal combustion engine is started in addition to the estimation of the pulsation torque. The internal combustion engine to which the present invention is applied is not limited to a spark ignition type internal combustion engine. The present invention may be applied to a diesel internal combustion engine. The internal combustion engine to which the present invention is applied is not limited to a four-cylinder internal combustion engine. The present invention may be applied to a single cylinder internal combustion engine and various internal combustion engines having two or more cylinders.

3 Motor generator
10A, 10B Internal combustion engine 10a Crankshaft 11 Cylinder 13 Electric motor (electric motor)
18 Intake valve 20 Spark plug 34 Rush adjuster 40 Vehicle control device (valve closing determination means, torque ratio calculation means, torque calculation means, control means)

Claims (5)

In the control apparatus for an internal combustion engine comprising a rotation speed detection means for detecting the rotation speed of a rotating body that rotates together with the crankshaft of the internal combustion engine or the crankshaft when the internal combustion engine is started,
The intake valve of the cylinder of the internal combustion engine is closed when the time differential value obtained by time-differentiating the rotational speed detected by the rotational speed detection means changes from a value larger than a predetermined threshold value to a value smaller than the threshold value. A control device comprising a valve closing determining means for determining   When the internal combustion engine is started, the valve closing determination means determines whether or not the intake valve is closed only for a cylinder that is initially closed after cranking of the internal combustion engine is started. The control device according to claim 1 to be performed. The internal combustion engine is a spark ignition type internal combustion engine provided with a spark plug,
The valve closing determination means determines whether or not an intake valve of a cylinder of the internal combustion engine is closed during a period from when cranking of the internal combustion engine is started to when ignition by the spark plug is started. The control device according to 1 or 2.   The control device according to claim 1, wherein the internal combustion engine is a two-cylinder internal combustion engine. The internal combustion engine is switched to a normal state in which the crankshaft can be driven and a normal state in which the closing timing of the intake valve becomes the first crank angle when the hydraulic pressure of the internal combustion engine is equal to or higher than a set pressure. A lash adjuster that switches to a low hydraulic pressure state in which the closing timing of the intake valve becomes a second crank angle earlier than the first crank angle when the hydraulic pressure from the oil pump is less than the set pressure,
When the cranking is started from the crank angle based on the closing timing when the intake valve is determined to be closed by the valve closing determination means and the crank angle at the start of cranking of the internal combustion engine, the cylinder Torque ratio calculating means for calculating a torque ratio that is a ratio between a torque expected to be applied to the crankshaft and a preset reference torque;
Torque calculating means for calculating a torque expected to be applied from the cylinder to the crankshaft during cranking of the internal combustion engine based on the torque ratio calculated by the torque ratio calculating means;
Control means for controlling the operation of the electric motor during cranking of the internal combustion engine based on the torque calculated by the torque calculating means,
The torque calculation means includes a transitional period from the start of cranking of the internal combustion engine until the cylinder that is first in the compression stroke after the cranking starts until the first expansion stroke after the cranking starts is completed. The control device according to any one of claims 1 to 4, wherein a calculation method for calculating torque is switched between after the transition period has elapsed.

Images