JP2010013973A - Valve system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid valve stamping when the rotation of a cam is stopped in a valve system, in which a cam rotated or rocked by a motor separately provided from an internal combustion engine opens and closes a valve. <P>SOLUTION: In this valve system for the internal combustion engine in which a cam rotated or rocked by the rotation of a motor separately provided from an internal combustion engine opens and closes a valve, when a rotating position of the cam is within a range for opening the valve, a rotating force is applied to the cam by magnetizing a nose of the cam and the valve to the same pole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

In recent years, a valve operating system has been proposed in which a cam is rotationally driven by a prime mover (for example, an electric motor) independent of an internal combustion engine (see, for example, Patent Document 1).
JP 2005-54732 A Japanese Utility Model Publication No. 61-198504 JP 2007-285292 A

  By the way, in the valve operating system as described above, the output shaft (crankshaft) of the internal combustion engine and the cam are not mechanically connected. For this reason, when a failure occurs in the valve operating system, the cam and the crankshaft are not synchronized, and there is a possibility that interference (valve stamp) between the cam and the piston occurs.

  On the other hand, a method of stopping the rotation of the cam when a failure occurs is conceivable. However, if the cam stops rotating with the valve opened, the valve stamp may not be avoided.

  The present invention has been made in view of the above circumstances, and in a valve operating system in which a cam rotated or swung by a prime mover independent of an internal combustion engine opens and closes a valve, when the rotation of the cam is stopped. The purpose is to avoid the occurrence of valve stamps.

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 rotated or swung by a prime mover independent of the internal combustion engine opens and closes a valve.
When the rotational position of the cam is in a range where the valve is opened, a power addition mechanism is provided that applies a rotational force to the cam independently of the prime mover.

  According to this invention, when the rotation of the cam is stopped (when the operation of the prime mover is stopped), if the valve is in the open state, the power addition mechanism applies a rotational force to the cam. Although it is preferable to add the rotational force by the power addition mechanism until the valve is closed, it may be added until the lift amount of the valve becomes an amount that cannot generate the valve stamp.

  As a result, the cam does not stop in a state where the rotational position of the cam belongs to a range in which the valve is opened (in other words, a range in which a valve stamp can be generated). For this reason, it is possible to avoid interference between the valve and the piston.

  Examples of the power addition mechanism according to the present invention include a mechanism that magnetizes the nose portion of the cam and the valve to the same polarity. In addition, when the prime mover is an electric motor, the electric motor is attached to the output shaft of the electric motor so that the cogging torque acts on the valve when the valve is opened, so that the electric motor functions as a power adding mechanism. May be.

The power addition mechanism according to the present invention is effective not only when a failure occurs in the valve operating system, but also when the internal combustion engine is fuel cut or when the internal combustion engine is reduced in cylinder. In other words, when the power addition mechanism is operated when the internal combustion engine is operated by fuel cut or when the internal combustion engine is operated by reduced cylinder operation, the intake valve can be closed without controlling the stop position of the cam.

  According to the present invention, in a valve operating system in which a cam rotated or swung by a prime mover independent of an internal combustion engine opens and closes a valve, it is possible to avoid the occurrence of a valve stamp when the rotation of the cam is stopped.

  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>

  First, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. An internal combustion engine 1 shown in FIG. 1 is a 4-stroke cycle spark ignition 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 determines the fuel injection valve 12 and the spark plug 1 based on the measured values of the various sensors.
3. The intake side drive mechanism 10 and the exhaust side drive mechanism 11 are electrically controlled.

  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, when a failure occurs in the valve train described above, the camshaft and the crankshaft 5 may not be synchronized. If the camshaft and the crankshaft 5 are not synchronized, the intake valve 8 or the exhaust valve 9 may interfere with the piston 3 (valve stamp). On the other hand, a method of stopping energization of each motor is conceivable. However, depending on the stop position of the camshaft, the intake valve 8 or the exhaust valve 9 may be opened, and the valve stamp may not be avoided.

  Therefore, the valve operating system of the present embodiment can apply a rotational force to the cam (camshaft) when the rotational position of the cam (camshaft) is in a range where the intake valve 8 or the exhaust valve 9 is opened. A power addition mechanism is provided.

  Hereinafter, the configuration of the power addition mechanism will be described with reference to FIGS. 3 to 5. The power addition mechanism is provided in each of the intake side drive mechanism 10 and the exhaust side drive mechanism 11. Since the power addition mechanism of the intake side drive mechanism 10 and the power addition mechanism of the exhaust side drive mechanism 11 have the same configuration, only the power addition mechanism of the intake side drive mechanism 10 will be described here.

  FIG. 3 is a side view of the second intake camshaft 84. In FIG. 3, the second intake camshaft 84 positioned between the second intake cam 82 of the second cylinder (# 2) and the second intake cam 82 of the third cylinder (# 3) has a cam-side coil 800. Is wrapped around. The cam side coil 800 is electrically connected to a cam side switch 801 that switches application / stop of excitation current to the cam side coil 800. The cam side switch 801 is controlled by the ECU 14.

  The flow of excitation current from the cam side switch 801 to the cam side coil 800 is such that the magnetic pole of the second intake cam 82 of the second cylinder (# 2) becomes N pole and the second intake of the third cylinder (# 3). The magnetic pole of the cam 82 is determined to be the S pole.

  FIG. 4 is a sectional view of the intake valve 8 and the valve lifter 80 of the second cylinder (# 2). In FIG. 4, a valve side coil 802 is wound around the stem of the intake valve 8 of the second cylinder (# 2). The valve side coil 802 is electrically connected to a valve side switch 803 that switches application / stop of excitation current to the valve side coil 802. The valve side switch 803 is controlled by the ECU 14.

  The flow of excitation current from the valve side switch 803 to the valve side coil 802 is such that the magnetic pole on the base end (upper end in FIG. 4) side of the stem is the S pole, and on the tip end (lower end in FIG. 4) side of the stem. The magnetic poles are determined to be N poles. In this case, the magnetic pole of the valve lifter 80 has the same N pole as the second intake cam 82 of the second cylinder (# 2).

FIG. 5 is a sectional view of the intake valve 8 and the valve lifter 80 of the third cylinder (# 3). In FIG. 5, the difference from the second cylinder (# 2) is only the winding direction of the valve side coil 802. That is, the winding direction of the valve side coil 802 of the third cylinder (# 3) is opposite to the winding direction of the valve side coil 802 of the second cylinder (# 2). In this case, the magnetic pole on the proximal end (upper end in FIG. 5) side of the stem is an N pole, and the magnetic pole on the distal end (lower end in FIG. 5) side of the stem is an S pole. As a result, the magnetic pole of the valve lifter 80 becomes the same S pole as the second intake cam 82 of the third cylinder (# 3).

  Instead of reversing the winding direction of the valve side coil 802 of the third cylinder (# 3) with respect to the second cylinder (# 2), the flow direction of the excitation current may be reversed.

  The cam side coil 800, the cam side switch 801, the valve side coil 802, and the valve side switch 803 correspond to a power addition mechanism. That is, when the ECU 14 controls the cam side switch 801 and the valve side switch 803 so that the excitation current is applied to the cam side coil 800 and the valve side coil 802, the second intake cam 82 and the valve lifter 80 are magnetized to the same polarity. The In that case, a repulsive force acts between the second intake cam 82 and the valve lifter 80. This repulsive force rotates the second intake cam 82 to separate the nose portion of the second intake cam 82 from the valve lifter 80, as indicated by the arrow R in FIG. Therefore, if the above-described power addition mechanism is activated when the second intake cam 82 is in the state where the intake valve 8 is opened, the intake valve 8 can be shifted to the closed state.

  The power addition mechanism provided on the first intake camshaft 83 has the same configuration as the power addition mechanism provided on the second intake camshaft 84.

  Next, the control procedure of the power addition mechanism in the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a control routine of the power addition mechanism. This control routine is a routine stored in advance in the ROM of the ECU 14 and is periodically executed by the ECU 14.

  In the control routine of FIG. 7, the ECU 14 first executes the process of S101. In S101, the ECU 14 determines whether or not a motor stop request is generated. The motor stop request is generated when a failure occurs in the valve operating system.

  If a negative determination is made in S101, the ECU 14 proceeds to S105 and maintains the power addition mechanism in a stopped state.

  If an affirmative determination is made in S101, the ECU 14 proceeds to S102. In S102, the ECU 14 stops the operation of the motor.

  Then, ECU14 progresses to S103 and operates a power addition mechanism. For example, the ECU 14 controls the cam side switch 801 and the valve side switch 803 so that an excitation current is applied to the cam side coil 800 and the valve side coil 802.

  In S104, the ECU 14 determines whether or not the lift amount of each valve has become a predetermined value or less. The predetermined value may be the maximum value of the lift amount that can avoid the valve stamp, or may be zero. Note that the determination in S104 can be performed based on the rotational position of each camshaft. The rotational position of each camshaft can be specified based on the output signal of the resolver or the output signal of the cam position sensor.

If a negative determination is made in S104, the ECU 14 returns to S103 and continues the operation of the power addition mechanism. On the other hand, if an affirmative determination is made in S104, the ECU 14
Proceeding to 105, the operation of the power addition mechanism is stopped.

  Depending on the type of failure, there may be a case where the lift amount of each valve cannot be accurately detected. In such a case, the ECU 14 may operate the power addition mechanism for a predetermined time instead of executing the process of S104 described above. The predetermined time is the time required for the valve in the valve open state to be closed by the power addition mechanism, and is determined experimentally in advance.

  According to the embodiment described above, it is possible to avoid the occurrence of a valve stamp when a failure occurs in the valve operating system.

  The magnetic poles of the second intake cam 82 and the valve lifter 80 are not limited to the examples shown in FIGS. 3 and 4 described above, and the magnetic poles of the second intake cam 82 and the valve lifter 80 in each cylinder 2 Should be determined to be the same polarity.

  3 and 4 described above, both the second intake cam 82 and the valve lifter 80 function as electromagnets. However, even if either the second intake cam 82 or the valve lifter 80 is a permanent magnet. Good.

  Furthermore, the arrangement of the cam side coil 800 and the valve side coil 802 is not limited to the arrangement shown in FIGS. 3 and 4 described above, and any arrangement is possible as long as the second intake cam 82 and the valve lifter 80 can be excited. May be.

  In the present embodiment, the example in which the power addition mechanism is operated when a failure occurs in the valve operating system has been described. However, the internal combustion engine 1 is operated in a fuel-cut operation, or the internal combustion engine 1 is operated in a reduced cylinder operation. It is also effective in cases. That is, if the power addition mechanism of the intake side drive mechanism 10 is operated when the internal combustion engine 1 is operated by fuel cut or when the internal combustion engine 1 is operated by reduced cylinder operation, the first intake camshaft 83 and the second intake cam The intake valve 8 can be closed without controlling the stop position of the shaft 84. As a result, the control logic can be simplified.

<Example 2>
Next, a second embodiment of the present invention will be described with reference to FIG. Here, a configuration different from that of the first embodiment will be described, and description of the same configuration will be omitted.

  The power addition mechanism of the present embodiment is a mechanism that applies a rotational force to the cam (camshaft) using the cogging torque of the motor. That is, as shown in FIG. 8, when the rotational position of the camshaft is at the rotational position for opening the valve, the motor is mounted so that the cogging torque of the motor shows a positive value. Specifically, the motor is mounted so that the cogging torque is maximized when the valve lift is maximized.

  According to this configuration, even if the valve is in the open state when the operation of the motor is stopped, the cam is rotated so as to close the valve by the cooperation of the cogging torque and the valve spring. As a result, the cam can be rotated until the lift amount of the valve reaches a lift amount that can avoid the valve stamp. For this reason, it is possible to obtain the same effect as the first embodiment described above.

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 side view of the 2nd intake camshaft. It is a side view of the intake valve of the second cylinder. It is a side view of the intake valve of the third cylinder. It is the figure which modeled the effect | action of the power addition mechanism. It is a flowchart which shows the control routine of a power addition mechanism. It is a figure which shows the relationship between the phase of cogging torque, and the phase of a cam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Piston 4 ... Connecting rod 5 ... Crankshaft 6 ... Intake port 7 ... Exhaust port 8 ... .... Intake valve 9 ... Exhaust valve 10 ... Intake side drive mechanism 11 ... Exhaust side drive mechanism 14 ... ECU
18 ... first motor 21 ... second motor 80 ... valve lifter 81 ... first intake cam 82 ... second intake cam 83 ... first intake cam shaft 84 ... second Intake cam shaft 87... Intake valve spring 800 .. Cam side coil 801 .. Cam side switch 802 .. Valve side coil 803 .. Valve side switch

Claims (3)

In a valve operating system of an internal combustion engine in which a cam rotated or rocked by a prime mover independent of the internal combustion engine opens and closes the valve,
A valve operating system for an internal combustion engine, comprising: a power addition mechanism that applies a rotational force to the cam independently of the prime mover when the rotational position of the cam is within a range for opening the valve.   2. The valve operating system for an internal combustion engine according to claim 1, wherein the power addition mechanism is a mechanism that magnetizes the nose portion of the cam and the valve to the same polarity.   3. The valve operating system for an internal combustion engine according to claim 1 or 2, wherein the power adding mechanism applies a rotational force to the cam when the valve stops in a valve open state.

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