JP2010116902A - Valve system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of approximating an operation mode of an intake valve and/or an exhaust valve to a desired mode, even when a request torque of a prime mover exceeds the upper limit value, in a valve system of an internal combustion engine for driving a cam by the prime moved independent of the internal combustion engine. <P>SOLUTION: This invention is the valve system of the internal combustion engine for driving the cam by the prime mover independent of the internal combustion engine. When the request torque as torque requested to the prime mover exceeds the upper limit value, a torque shortage of the prime mover is compensated by controlling an electric motor by a torque command value of larger amplitude than the request torque. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve operating system for an internal combustion engine in which a cam is driven by a prime mover independent of the internal combustion engine.

Conventionally, a valve operating system for an internal combustion engine in which a cam is driven by a prime mover independent of the internal combustion engine has been proposed. For example, a valve operating system using an electric motor as a prime mover independent of an internal combustion engine has been proposed (see, for example, Patent Document 1).
JP 2007-154848 A JP 2005-180238 A JP 2007-292045 A Japanese Patent No. 3690811

  By the way, during the operation of the above-described conventional valve operating system, the required torque of the prime mover may exceed the upper limit depending on the operating state of the internal combustion engine. In such a case, there is a possibility that the intake valve or the exhaust valve cannot be operated in a desired manner (timing or speed).

  On the other hand, a method of increasing the rating of the prime mover is conceivable, but there is a problem that the size and weight of the valve operating system increase and the in-vehicle performance deteriorates.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to make the required torque of the prime mover exceed the upper limit value in the valve operating system of the internal combustion engine in which the cam is driven by the prime mover independent of the internal combustion engine. Even in such a case, the present invention provides a technique capable of approximating the operation mode of the intake valve and / or the exhaust valve to a desired mode.

  In order to solve the above-described problem, the present invention provides a valve operating system for an internal combustion engine in which a cam is driven by a prime mover independent of the internal combustion engine. The prime mover was controlled according to the torque command value with a large amplitude.

Specifically, the present invention relates to a valve operating system for an internal combustion engine in which a cam is driven by a prime mover independent of the internal combustion engine.
Control means for controlling the electric motor with a torque command value having an amplitude larger than the required torque when a required torque as a torque required for the prime mover exceeds an upper limit value is provided.

  Here, the “upper limit value” corresponds to the maximum torque that can be generated by the prime mover. Further, “the required torque exceeds the upper limit value” means a torque (requested torque) waveform required for a period from the start of valve opening to the end of valve closing (hereinafter referred to as “valve operating period”). It means that at least part of the required torque exceeds the upper limit value.

When the required torque exceeds the upper limit value, the torque generated by the prime mover is insufficient during the valve operation period in which the required torque exceeds the upper limit value. Therefore, the rotational speed of the cam becomes lower than the target value, and there is a possibility that the valve opening / closing timing and the operating angle are far from the target value. As a result, the internal combustion engine may not be able to exhibit desired performance, and exhaust emission may be deteriorated.

  On the other hand, when the prime mover is operated with a torque command value having a larger amplitude than the required torque, the maximum value of the generated torque of the prime mover is limited to the upper limit value as in the case where the prime mover is operated according to the required torque. However, the timing at which the generated torque of the prime mover reaches the upper limit is earlier than when the prime mover is operated according to the required torque. That is, the increase rate of the generated torque of the prime mover is larger than when the prime mover is operated according to the required torque. As a result, the rotational inertia force of the cam increases, so that the valve opening / closing timing and operating angle approximate the target value.

  In the present invention, the control means may control the prime mover so that the integrated value of the required torque is equal to the integrated value of the torque command value. In other words, the control means may determine the torque command value so that the integrated value of the required torque is equal to the integrated value of the torque command value. In that case, the angular velocity of the cam when the prime mover operates according to the torque command value is the cam when the prime mover can generate a torque equivalent to the required torque (assuming that the generated torque of the prime mover is not limited to the upper limit value). Approximate the angular velocity of. As a result, the rotational position of the cam (actual phase of the cam with reference to the crank angle) is prevented from moving away from the target rotational position (target phase of the cam with reference to the crank angle).

  Further, in the present invention, the control means is configured so that the phase of the waveform extreme value obtained by integrating the torque command value is equal to the phase of the waveform extreme value obtained by integrating the required torque. May be determined.

  In other words, the control means is the timing at which the waveform obtained by integrating the torque command value shows the extreme value (timing based on the crank angle) and the timing at which the waveform obtained by integrating the required torque shows the extreme value (crank The torque command value may be determined so that the timing with respect to the angle becomes equal.

  When the torque command value is determined in this manner, the cam rotation position (actual cam phase based on the crank angle) during the valve operation period is far from the target rotation position (cam target phase based on the crank angle). Is suppressed.

  According to the present invention, in a valve operating system for an internal combustion engine in which a cam is driven by a prime mover independent of the internal combustion engine, even when the required torque of the prime mover exceeds the upper limit value, the intake valve and / or the exhaust valve Can be approximated to a desired mode.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of a valve operating system for an internal combustion engine to which the present invention is applied.

An internal combustion engine 1 shown in FIG. 1 is a four-stroke cycle spark ignition type internal combustion engine (gasoline engine) having a plurality of cylinders 2. Each cylinder 2 of the internal combustion engine 1 is internally slidably provided with a piston 3. The piston 3 is connected to the crankshaft 5 via a connecting rod 4.

  The inside of the cylinder 2 communicates with the intake port 6 and the exhaust port 7. The opening end of the intake port 6 in the cylinder 2 is opened and closed by an intake valve 8. An open end of the exhaust port 7 in the cylinder 2 is opened and closed by an exhaust valve 9. The intake valve 8 and the exhaust valve 9 are respectively opened and closed by an intake side drive mechanism 10 and an exhaust side drive mechanism 11.

  The intake port 6 communicates with the intake passage 60. The intake air flowing through the intake passage 60 is guided to the intake port 6. The intake air guided to the intake port 6 is sucked into the cylinder 2 when the intake valve 8 is opened. At this time, when the fuel injection valve 12 attached to the intake passage 60 injects fuel toward the intake port 6, the fuel is also taken into the cylinder 2 together with the intake air.

  The fuel and the intake air (air mixture) guided into the cylinder 2 are burned using the spark generated by the spark plug 13 as a spark. Gas burned in the cylinder 2 (burned gas) is discharged to the exhaust port 7 when the exhaust valve 9 is opened. The exhaust port 7 communicates with the exhaust passage 70, and the burnt gas described above is discharged from the exhaust port 7 into the atmosphere through the exhaust passage 70.

  The internal combustion engine 1 configured as described above is provided with an ECU 14. The ECU 14 is an electronic control unit that includes a CPU, a ROM, a RAM, a backup RAM, and the like. The ECU 14 is electrically connected to various sensors such as a crank position sensor 15, a water temperature sensor 16, and an ignition switch 17.

  The crank position sensor 15 is a sensor that outputs a signal corresponding to the rotational position of the crankshaft 5. The water temperature sensor 16 is a sensor that outputs a signal corresponding to the temperature of the cooling water circulating through the internal combustion engine 1.

  The ECU 14 electrically controls the fuel injection valve 12, the spark plug 13, the intake side drive mechanism 10, and the exhaust side drive mechanism 11 based on the measurement values of the various sensors described above.

  Here, the configuration of the intake side drive mechanism 10 will be described with reference to FIG. 2 represent the first to fourth cylinders of the internal combustion engine 1, respectively. The combustion order of the first cylinder (# 1) to the fourth cylinder (# 4) is as follows: the first cylinder (# 1) → the third cylinder (# 3) → the fourth cylinder (# 4) → the second cylinder ( # 2).

  Two intake valves 8 are provided in each of the first cylinder (# 1) to the fourth cylinder (# 4). A valve lifter 80 is attached to the stem base end of the intake valve 8. The intake valve 8 is urged in the valve closing direction by an intake side valve spring 87, and the valve lifter 80 is pressed against the first intake cam 81 or the second intake cam 82 by the urging force.

  The first intake cam 81 is a cam that opens and closes the intake valves 8 of the first cylinder (# 1) and the fourth cylinder (# 4), and is fixed to the first intake camshaft 83. The second intake cam 82 is a cam that opens and closes the intake valves 8 of the second cylinder (# 2) and the third cylinder (# 3), and is fixed to the second intake camshaft 84. That is, in this embodiment, two cylinders having different combustion timings are configured to share one intake camshaft.

  The first intake camshaft 83 and the second intake camshaft 84 are arranged coaxially and are supported by the internal combustion engine 1 so as to be rotatable or swingable in the circumferential direction independently of each other.

A first driven gear 85 is fixed to one end of the first intake camshaft 83. The first driven gear 85 meshes with the first output gear 19 fixed to the output shaft of the first motor 18. Hereinafter, the first driven gear 85 and the first output gear 19 are collectively referred to as a first reduction mechanism.

  In this case, the rotational torque of the first motor 18 is transmitted to the first intake camshaft 83 via the first reduction mechanism. Therefore, the first motor 18 can rotate or swing the first intake camshaft 83 in the circumferential direction via the first reduction mechanism.

  A second driven gear 86 is coaxially fixed to a part of the outer peripheral surface of the second intake camshaft 84. The second driven gear 86 meshes with the second output gear 22 fixed to the output shaft of the second motor 21. Hereinafter, the second driven gear 86 and the second output gear 22 are collectively referred to as a second reduction mechanism. It is assumed that the reduction ratio by the second reduction mechanism is equivalent to that of the first reduction mechanism described above.

  In this case, the rotational torque of the second motor 21 is transmitted to the second intake camshaft 84 via the second reduction mechanism. Therefore, the second motor 21 can rotate or swing the second intake camshaft 84 in the circumferential direction via the second reduction mechanism.

  A first cam position sensor 30 that detects the rotational position of the first intake camshaft 83 is attached to the first intake camshaft 83. A second cam position sensor 31 that detects the rotational position of the second intake camshaft 84 is attached to the second intake camshaft 84. The detection signals of the first cam position sensor 30 and the second cam position sensor 31 are input to the ECU 14.

  The first motor 18 includes a first resolver 20 that detects the rotation angle (phase) of the output shaft, and a detection signal of the first resolver 20 is input to the ECU 14. The second motor 21 includes a second resolver 23 that detects the rotation angle of the output shaft, and a detection signal of the second resolver 23 is input to the ECU 14.

  Although the description of the configuration of the exhaust side drive mechanism 11 is omitted, it may be configured such that two motors and two camshafts are provided similarly to the intake side drive mechanism 10, or each of the motor and the camshaft is one. One may be provided.

  In the valve train configured as described above, the ECU 14 rotates or swings each motor at a timing synchronized with the rotation of the crankshaft 5, whereby the first cylinder (# 1) to the fourth cylinder (# 4). ) Of the intake valve 8 and the exhaust valve 9 can be opened and closed at the timing synchronized with the rotation of the crankshaft 5 (that is, the timing synchronized with the combustion cycle of the first cylinder (# 1) to the fourth cylinder (# 4)). .

  By the way, the torque required for each motor 18, 21 during the period from when the intake valve 8 starts to open until the valve is closed (valve operation period) is the upper limit value (maximum value of torque that can be generated by the motors 18, 21). ), The rotational speed of the intake cams 81 and 82 may be lower than the target value. In that case, there is a possibility that the opening / closing timing and the operating angle of the intake valve 8 are far from the target value.

  FIG. 3 is a diagram showing torque command values (requested torques) input to the motors 18 and 21 during the valve operation period. In FIG. 3, it is assumed that the intake cams 81 and 82 and the motors 18 and 21 are operating in a mode that rotates continuously in one direction (forward rotation mode).

If the torque command value is equal to or less than the upper limit value (the maximum value of torque that can be generated by the motors 18 and 21) Tmmax, the torque actually generated by the motors 18 and 21 (hereinafter referred to as “actual torque”).
Is a waveform substantially equivalent to the torque command value shown in FIG.

  On the other hand, when the torque command value exceeds the upper limit value Tmmax, as shown in FIG. 4, a period during which the torque command value (broken line in FIG. 4) exceeds the upper limit value Tmmax (hereinafter referred to as “torque shortage period”). ) At P, the actual torque of the motor (solid line in FIG. 4) is limited to the upper limit value Tmmax. As a result, in the torque shortage period P, the rotational speeds of the motors 18 and 21 and the intake cams 81 and 82 may be lower than the target rotational speed. In that case, there is a possibility that the opening / closing timing and the operating angle of the intake valve 8 are far from the target value.

  If the opening / closing timing or operating angle of the intake valve 8 is far from the target value, a change in the amount of air sucked into the cylinder 2 or the like occurs, and the generated torque of the internal combustion engine 1 falls below the required torque, or the internal combustion engine 1 The situation where the exhaust emission of the gas increases is induced.

  Therefore, in this embodiment, when the torque command values of the motors 18 and 21 exceed the upper limit value Tmmax, the amplitude of the torque command value during the valve operation period is corrected to be increased as shown in FIG. The solid line in FIG. 5 indicates the torque command value after correction, and the broken line in FIG. 5 indicates the torque command value before correction.

  In this case, the actual torque of the motors 18 and 21 is limited to the upper limit value Tmmax, as shown by the solid line in FIG. 6, as in the case where the torque command value is not corrected (broken line in FIG. 6). However, the timing at which the actual torques of the motors 18 and 21 reach the upper limit value Tmmax is higher when the torque command value is corrected (t1 in FIG. 6) than when the torque command value is not corrected (t10 in FIG. 6). ) Is faster. That is, the rate of increase (inclination) of the actual torque is greater when the torque command value is corrected than when the torque command value is not corrected.

  As a result, the rotational inertia force of the motors 18 and 21 and the intake cams 81 and 82 increases, so that the opening / closing timing and operating angle of the intake valve 8 can be approximated to the target values. Thus, the control means concerning this invention is implement | achieved when ECU14 correct | amends a torque instruction value.

  The increase correction amount of the torque command value is such that the total area of the areas B1 and B2 in FIG. 7 is equal to the area of the area A1 (A1 = B1 + B2), and the total area of the areas B3 and B4 is the area of the area A2. It may be determined to be equal (A2 = B3 + B4).

  In this case, since the angular velocities of the intake cams 81 and 82 are substantially equal to the target value (the angular velocity when the actual torque is equal to the torque command value before correction without being limited to the upper limit value Tmmax), the intake valve 8 It becomes easy to approximate the opening / closing timing and working angle of the valve to the target value.

  Further, a waveform (hereinafter referred to as “reference angular velocity waveform”) obtained by converting the torque command value before correction into angular velocity (hereinafter referred to as “reference angular velocity waveform”) and a waveform obtained by converting actual torque into angular velocity (hereinafter referred to as integrating actual torque). The increase correction amount of the torque command value may be determined so that the amplitude and phase of “corrected angular velocity waveform” are substantially equal.

  For example, the ECU 14 matches the maximum amplitude value of the reference waveform with the maximum amplitude value of the correction waveform, the timing at which the reference waveform shows the maximum amplitude value (crank angle), and the correction waveform shows the maximum amplitude value. The increase correction amount of the torque command value may be determined so that the timing (crank angle) matches.

When the increase correction amount of the torque command value is thus determined, the rotation angle (phase) of the intake cams 81 and 82 relative to the crank angle is set to the target value (the torque command before correction without limiting the actual torque to the upper limit value Tmmax). Approximate the cam phase when it is equal to the value). As a result, the opening / closing timing and operating angle of the intake valve 8 can be easily approximated to the target value.

  In the embodiment described above, the intake side drive mechanism 10 is taken as an example, but the same control can be applied to the exhaust side drive mechanism 11.

1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. It is a figure which shows schematic structure of an intake side drive mechanism. It is a figure which shows the change of the torque command value in a valve | bulb operating period. It is a figure which shows the actual torque when a torque command value exceeds an upper limit. It is a figure which shows the torque command value before correction | amendment, and the torque command value after correction | amendment. It is a figure which shows the actual torque corresponding to the torque command value before correction | amendment, and the actual torque corresponding to the torque command value after correction | amendment. It is a figure explaining the method of determining the correction amount of a torque command value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 8 ... Intake valve 9 ... Exhaust valve 10 ... Intake side drive mechanism 11 ... Exhaust side drive mechanism 14 ... ECU (control) means)
15 ... Crank position sensor 18 ... First motor (motor)
19 ... Second motor (motor)
30 ... first cam position sensor 31 ... second cam position sensor 80 ... valve lifter 81 ... first intake cam 82 ... second intake cam 83 ... first intake cam shaft 84 ..Second intake camshaft 87 ... intake side valve spring

Claims (3)

In a valve operating system for an internal combustion engine in which a cam driven by a prime mover independent of the internal combustion engine opens and closes the valve,
Control for operating the prime mover with a torque command value having an amplitude larger than the required torque when the required torque, which is the torque that should be generated by the prime mover, exceeds the upper limit during the period from the start of valve opening to the end of valve closing. A valve operating system for an internal combustion engine, characterized by comprising means.   2. The valve operating system for an internal combustion engine according to claim 1, wherein the control means determines the torque command value so that an integrated value of the required torque is equal to an integrated value of the torque command value.   3. The control means according to claim 1, wherein the control means is configured so that the phase of the extreme value of the waveform obtained by integrating the torque command value is equal to the phase of the extreme value of the waveform obtained by integrating the required torque. A valve operating system for an internal combustion engine, wherein a command value is determined.

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