JP2010270701A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge an operation region allowing cylinder cut-off operation to a low temperature side. <P>SOLUTION: In a cylinder cut-off operation switching part carrying out switching from all cylinder operation to cylinder cut-off operation, if it is determined that there is a cylinder cut-off operation demand in S1, go to S2, and a cooling water temperature Tw is compared with a predetermined lower limit temperature Ts. In S2, if the cooling water temperature Tw is at the lower limit temperature Ts or below, it is determined that it is the time of low temperature, go to S3, and an operating angle of an intake valve is reduced within a range of not influencing torque fluctuation by a continuous variable lift valve system. Then, in S4, switching from the all cylinder operation to the cylinder cut-off operation is carried out by a valve stopping mechanism. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine capable of switching between all-cylinder operation for operating all cylinders of a multi-cylinder internal combustion engine and reduced-cylinder operation for stopping some cylinders.

  Patent Document 1 discloses that a multi-cylinder internal combustion engine includes a switching mechanism that switches between a movable state and a stopped state of an engine valve by engagement / disengagement with the engine valve, and a drive mechanism that operates the switching mechanism. Yes. The switching mechanism includes a movable plate that is slidably supported by the valve lifter on the rotary cam side, and that is detachably engaged with the slider on the engine valve side and is hydraulically driven. Then, by operating the drive mechanism in the base circle section of the rotating cam, the movable plate is slid by the hydraulic pressure to switch the engagement and disengagement between the movable plate and the slider on the engine valve side. And switching.

Japanese Patent Application Laid-Open No. 10-141034

  However, in some cylinders, as described in Patent Document 1, when the engine valve is switched from a movable state to a stopped state by hydraulic pressure to switch from all-cylinder operation to reduced-cylinder operation, the lower the engine temperature, The time required for switching to the reduced-cylinder operation tends to be longer due to the increased viscosity of the oil.

  Therefore, in order to prevent the switching time to the reduced-cylinder operation from exceeding the base circle section (that is, the switching time to the reduced-cylinder operation is insufficient), the engine temperature that can be switched to the reduced-cylinder operation is reduced. By setting the lower limit value, it was necessary to limit the operating range in which reduced cylinder operation is possible on the low temperature side.

  In view of such a situation, an object of the present invention is to expand an operation range in which reduced-cylinder operation is possible to a low temperature side.

  For this reason, in the present invention, an operating cylinder switching mechanism for switching between all-cylinder operation for operating all cylinders of a multi-cylinder internal combustion engine and reduced-cylinder operation for stopping a part of these cylinders, and an operating angle of the engine valve And a working angle variable mechanism for changing. In addition, when the reduced cylinder operation is requested during all cylinder operation and the engine temperature is equal to or lower than the predetermined temperature, all cylinder operation is performed by the operating cylinder switching mechanism after the operating angle is reduced by the operating angle variable mechanism. Switch from to reduced cylinder operation.

  According to the present invention, when the reduced cylinder operation is requested during all cylinder operation and the engine temperature is equal to or lower than the predetermined temperature, the operating angle of the engine valve is reduced, thereby reducing the base circle section at low temperatures. Since it can take a long time and the switching time to the reduced-cylinder operation is ensured, the operating range in which the reduced-cylinder operation can be performed can be expanded to the low temperature side.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The perspective view which shows the whole structure of a variable valve apparatus. 2 is an exploded perspective view of the variable valve operating apparatus shown in FIG. Exploded perspective view showing the configuration of the single valve switching mechanism Exploded perspective view showing the configuration of the valve stop mechanism Sectional view of the valve stop mechanism cut along a plane including the axis of the rocker shaft and the axis of the pin hole Flow chart showing main flow of reduced cylinder operation switching control Time chart showing an example of reduced cylinder operation switching control at low temperatures

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of an internal combustion engine according to an embodiment of the present invention.

  The internal combustion engine 101 is a gasoline engine having a plurality of cylinders 102. Each cylinder 102 of the internal combustion engine 101 is provided with two intake valves (engine valves) 103 and two exhaust valves (engine valves) 104. A piston 105 is slidably inserted into the cylinder 102. A combustion chamber 106 is formed in the cylinder 102 by being partitioned by a piston 105 and an inner wall of the cylinder 102. A spark plug 107 that ignites the air-fuel mixture in the combustion chamber 106 is provided at the upper portion of the cylinder 102. The piston 105 is connected to the crankshaft 109 via a connecting rod 108. The internal combustion engine 101 is provided with a rotation speed sensor 110 that measures the rotation angle of the crankshaft 109. The output of the rotational speed sensor 110 is input to an ECU (electronic control unit) 130 described later, and the engine rotational speed of the internal combustion engine 101 is detected based on this input.

  The combustion chamber 106 communicates with the intake passage 112 via the intake port 111. The intake port 111 is provided with a fuel injection valve 113 that injects combustion into the combustion chamber 106. The intake passage 112 is provided with a throttle valve 114 that can control the amount of air flowing through the intake passage 112. The throttle valve 114 is driven by a motor 115 to adjust its opening. The motor 115 is controlled by the ECU 130. An intake pressure sensor 116 that measures the pressure of intake air flowing through the intake passage 112 is provided in the intake passage 112 on the downstream side of the throttle valve 114. An air flow meter 117 that measures the amount of air flowing into the intake passage 112 is provided in the intake passage 112 upstream of the throttle valve 114. The outputs of the intake pressure sensor 116 and the air flow meter 117 are input to the ECU 130.

  The combustion chamber 106 communicates with the exhaust passage 119 via the exhaust port 118. An exhaust purification device 120 is disposed in the middle of the exhaust passage 119. An exhaust passage 119 upstream of the exhaust purification device 120 is provided with an air-fuel ratio sensor 121 that detects an air-fuel ratio based on components of exhaust flowing through the exhaust passage 119. The output of the air-fuel ratio sensor 121 is input to the ECU 130.

  The intake port 111 is opened and closed by the intake valve 103. The intake valve 103 is driven in conjunction with the rotation of the intake camshaft 122. The exhaust port 118 is opened and closed by the exhaust valve 104. The exhaust valve 104 is driven in conjunction with the rotation of the exhaust camshaft 123. The internal combustion engine 101 of the present embodiment is provided with a variable valve operating device 140 that makes the valve operating characteristics of the intake valve 103 variable. Details of the variable valve apparatus 140 will be described later.

  The ECU 130 includes a rotation speed sensor 110, an intake pressure sensor 116, an air flow meter 117, an air-fuel ratio sensor 121, a water temperature sensor 124 that measures the temperature Tw of cooling water that cools the internal combustion engine 101, and an accelerator pedal (not shown). The output of various sensors such as the accelerator opening sensor 125 that detects the amount of depression of the accelerator as the accelerator opening is input. Various devices such as a spark plug 107, a fuel injection valve 113, a motor 115, and a variable valve operating device 140 are connected to the ECU 130. ECU 130 outputs control signals for various devices based on data input from various sensors, and controls the operation of these devices.

  Here, the configuration of the variable valve operating apparatus 140 will be described with reference to FIGS.

  FIG. 2 shows the overall configuration of the variable valve operating apparatus 140 in one embodiment of the present invention. FIG. 3 is an exploded view of the variable valve apparatus 140 shown in FIG. FIG. 4 shows the configuration of the single valve switching mechanism provided in the variable valve operating apparatus 140. FIG. 5 shows the configuration of the valve stop mechanism provided in the variable valve operating apparatus 140. FIG. 6 shows a cross section of the valve stop mechanism taken along a plane including the axis of the rocker shaft and the axis of the pin hole.

The variable valve operating device 140 changes only the valve opening characteristic of a continuously variable mechanism section that continuously varies the valve opening characteristic of the intake valve 103 and one of the two intake valves 103 of each cylinder 102. A swirl control mechanism unit and a valve stop mechanism unit that can stop the lift operation of the intake valve 103 are provided. Here, the continuously variable mechanism functions as a working angle varying mechanism in the present invention, and changes the working angle (opening period) of the intake valve 103. In addition, the swirl control mechanism unit can generate a swirl flow in the cylinder 102 by closing only one of the two intake valves 103 of each cylinder 102. Further, the valve stop mechanism functions as an operating cylinder switching mechanism in the present invention, and switches between full cylinder operation for operating all cylinders of the internal combustion engine 101 and reduced cylinder operation for stopping some cylinders. The movable state and the stopped state of the two intake valves 103 of each cylinder 102 are switched.
[1] Continuously Variable Mechanism Unit The variable valve mechanism 140 includes a continuously variable lift valve mechanism 20 that mechanically changes the valve opening characteristics (working angle and lift amount) of the intake valve 103. Specifically, the variable valve operating device 140 has a rocker arm type mechanical valve operating mechanism, and a rotary motion of the intake camshaft 122 is caused by a first drive cam 12 provided on the intake camshaft 122, which will be described later. The input arm 72 and the transmission arm 74) are converted into a swinging motion, and the intake valve 103 supported by the transmission arm 74 is converted into a lift operation in the vertical direction. In the variable valve operating apparatus 140, the rocker arm is not directly driven by the first drive cam 12, but the continuous variable lift valve mechanism 20 is interposed between the first drive cam 12 and the rocker arm.

  The continuously variable lift valve mechanism 20 is a mechanism that can continuously change the rocking motion of the rocker arm with respect to the rotational motion of the first drive cam 12. The variable valve operating device 140 can continuously change the operating angle and lift amount of the intake valve 103 by changing the rocking amount and rocking timing of the rocker arm by variably controlling the continuous variable lift valve mechanism 20. It has become.

  The continuously variable lift valve mechanism 20 includes a control shaft 22, a control arm 24, a link arm 26, a swing cam arm 28, a first roller 30, and a second roller 32. The control shaft 22 is disposed in parallel to the intake cam shaft 122. The rotation angle of the control shaft 22 can be controlled to an arbitrary angle by an actuator (not shown) such as a motor.

  The swing cam arm 28 is supported by the control shaft 22 so as to be swingable, and the tip thereof is disposed toward the upstream side in the rotation direction of the first drive cam 12. A slide surface 34 that contacts the second roller 32 is formed on the side of the swing cam arm 28 that faces the first drive cam 12. The slide surface 34 is formed in a curved surface such that the distance from the first drive cam 12 gradually decreases as the second roller 32 moves from the distal end side of the swing cam arm 28 toward the axial center side of the control shaft 22. ing. A swing cam surface 36 is formed on the opposite side of the slide surface 34. The swing cam surface 36 is separated from the base circle 36a and a base circle 36a formed so that the distance from the swing center of the swing cam arm 28 (that is, the axis center of the control shaft 22) is constant. The working surface 36b is formed so that the distance from the axis center of the control shaft 22 increases as the position increases.

The other detailed configuration and operation of the continuously variable lift valve mechanism 20 are the same as those disclosed in detail in, for example, Japanese Patent Application Laid-Open No. 2006-70738. Is omitted.
[2] About Swirl Control Mechanism Unit Next, a detailed configuration of the swirl control mechanism unit will be described with reference to FIGS.

  The variable valve operating apparatus 140 can obtain a certain valve opening characteristic of the valve opening characteristic of one of the two intake valves 103 arranged in parallel (the second right intake valve 103R in FIG. 3). A fixing mechanism 40 is provided. As shown in FIGS. 2 and 3, the intake camshaft 122 is provided with a second drive cam 14 disposed adjacent to the first drive cam 12 in addition to the first drive cam 12 for each cylinder. Yes. The fixing mechanism 40 is interposed between the second drive cam 14 and the swing cam arm 28R. The fixing mechanism 40 links the swing motion of the swing cam arm 28 </ b> R with the rotational motion of the second drive cam 14, and includes a large lift arm 44 driven by the second drive cam 14. The large lift arm 44 is arranged on the control shaft 22 along with the second swing cam arm 28R, and can rotate independently of the second swing cam arm 28R. An input roller 46 that contacts the peripheral surface of the second drive cam 14 is rotatably supported by the large lift arm 44. A lost motion spring (not shown) is applied to the large lift arm 44, and the spring force acts as a biasing force that presses the input roller 46 against the peripheral surface of the second drive cam 14.

  The swirl control mechanism includes a one-valve switching mechanism 50 for coupling and releasing the large lift arm 44 and the second swing cam arm 28R. The single valve switching mechanism 50 is for selectively switching the interlocking destination of the lift operation of the second intake valve 103R between the continuously variable lift valve mechanism 20 and the fixed mechanism 40.

  As shown in FIG. 4, the large lift arm 44 is provided with a pin 52 that can be taken in and out toward the second swing cam arm 28R. The large lift arm 44 is formed with a hydraulic chamber 54 having an opening on the second swing cam arm 28 </ b> R side, and the pin 52 is fitted into the hydraulic chamber 54. The hydraulic oil is supplied to the hydraulic chamber 54 via a hydraulic passage (not shown). When the hydraulic pressure in the hydraulic chamber 54 is increased by such a configuration, the pin 52 is pushed out from the hydraulic chamber 54 toward the second swing cam arm 28R by the hydraulic pressure.

  On the other hand, a pin hole 56 having an opening on the large lift arm 44 side is formed in the second swing cam arm 28R. The pin 52 and the pin hole 56 are arranged on the same arc centered on the control shaft 22. Thus, when the second swing cam arm 28R is positioned at a predetermined rotation angle with respect to the large lift arm 44, the position of the pin hole 56 and the position of the pin 52 are made to coincide. A return spring 58 and a piston 60 are arranged in the pin hole 56 from the back side.

  With such a configuration, the pin 52 abuts on the piston 60 when the position of the pin hole 56 and the position of the pin 52 coincide. At this time, if the force in which the hydraulic pressure in the hydraulic chamber 54 pushes the pin 52 is greater than the force by which the return spring 58 pushes the piston 60, the pin 52 pushes the piston 60 into the back of the pin hole 56. It enters into the pin hole 56. By inserting the pin 52 into the pin hole 56, the swing cam arm 28 </ b> R and the large lift arm 44 are coupled via the pin 52. That is, the single valve switching mechanism 50 is configured by the pin 52, the hydraulic chamber 54 to which hydraulic oil is supplied, the pin hole 56, the return spring 58, and the piston 60.

  In the variable valve operating apparatus 140, the pin 52 and the pin hole 56 are configured such that their positions coincide with each other when the swing cam arm 28R is positioned at a predetermined rotation angle with respect to the large lift arm 44. When the positions of the pin 52 and the pin hole 56 overlap, the pin 52 is inserted into the pin hole 56, and the large lift arm 44 is coupled to the second swing cam arm 28R. In the variable valve operating device 140, the large lift arm 44 is coupled to the second swing cam arm 28 </ b> R by the single valve switching mechanism 50, so that the interlocking destination of the lift operation of the second intake valve 103 </ b> R is changed from the continuous variable lift valve operating mechanism 20. Switching to the fixing mechanism 40 is possible. Conversely, by releasing the coupling between the large lift arm 44 and the second swing cam arm 28R by the one-valve switching mechanism 50, the interlocking destination of the lift operation of the second intake valve 103R is changed from the fixed mechanism 40 to the continuously variable lift valve mechanism. 20 can be switched.

  When the large lift arm 44 and the second swing cam arm 28R are not coupled, the rotational motion of the intake camshaft 122 is transferred from the first drive cam 12 through the first roller 30 and the second roller 32 to the first swing cam. This is transmitted to the slide surfaces 34 of the moving cam arm 28L and the second swing cam arm 28R. Therefore, in this case, the operating angle and lift amount of the first intake valve 103L and the second intake valve 103R can be controlled in conjunction with the rotation of the control shaft 22 (both valve variable control). ).

On the other hand, when the large lift arm 44 and the second swing cam arm 28R are coupled, the rotational motion of the intake cam shaft 122 is transferred from the second drive cam 14 via the large lift arm 44 to the second swing cam arm 28R. Is transmitted. The large lift arm 44 and the second swing cam arm 28R rotate the control shaft 22 and move the position of the second roller 32R on the slide surface 34R to a position where a predetermined lift amount and operating angle can be obtained. Combined with Therefore, the valve opening characteristic of the second intake valve 103R in this case is mechanically determined by the shape and positional relationship of the second drive cam 14, the large lift arm 44, and the second swing cam arm 28R, and the rotation of the control shaft 22 Regardless of the angle, the valve opening characteristic is always fixed. On the other hand, the rotational motion of the intake camshaft 122 is transmitted from the first drive cam 12 to the first swing cam arm 28L via the first roller 30 and the second roller 32. Accordingly, the valve opening characteristic of the first intake valve 103L in this case changes in conjunction with the rotation angle of the control shaft 22 as in the case where the large lift arm 44 and the swing cam arm 28R are not coupled. . As described above, according to the variable valve operating apparatus 140, the valve opening characteristic of only the first intake valve 103L can be variably controlled in a state where the large lift arm 44 and the second swing cam arm 28R are coupled. It becomes possible (single valve variable control).
[3] Valve Stop Mechanism Section As shown in FIGS. 2 and 3, the variable valve operating apparatus 140 performs the lift operation of the first intake valve 103 </ b> L between the first swing cam arm 28 </ b> L and the first intake valve 103 </ b> L. A valve stop mechanism 70 is provided that can be stopped using hydraulic pressure. The valve stop mechanism 70 is similarly incorporated between the second swing cam arm 28R and the second intake valve 103R.

  FIG. 5A is a view showing the valve stop mechanism 70 on the second intake valve 103R side, and FIG. 5B is a view of the input arm 72 seen from the opposite direction to FIG. 5A. . FIG. 6 is a cross-sectional view of the valve stop mechanism 70 cut along a plane including the axis line of the rocker shaft 76 and the axis line of the pin hole 88, as viewed from the end of the intake valve 103R on the non-valve element side. is there.

  Here, the configuration of the valve stop mechanism 70 on the second intake valve 103R side will be described as an example, but the valve stop mechanism 70 on the first intake valve 103L side is configured similarly.

  As shown in FIGS. 3 and 6, the valve stop mechanism 70 includes two types of arms, that is, an input arm 72 and a transmission arm 74. Both the input arm 72 and the transmission arm 74 are rotatably supported by the rocker shaft 76.

  The input arm 72 is an arm that receives the input of the drive cams 12 and 14 via the second swing cam arm 28R. An input roller 78 that contacts the swing cam surface 36 of the second swing cam arm 28R is rotatably supported by the input arm 72. Further, a spring seat 80 for applying a lost motion spring 79 is provided at the end of the input arm 72.

  The transmission arm 74 is an arm that transmits the input of the drive cams 12 and 14 transmitted through the input arm 72 to the second intake valve 103R. A valve pressing portion 82 is provided at the end of the transmission arm 74 on the non-rocker shaft side. The valve pressing portion 82 is supported by the valve shaft 18R of the second intake valve 103R with a hydraulic lash adjuster 84 interposed. In a state where the transmission arm 74 and the input arm 72 are coupled, the input roller 78 of the input arm 72 is urged by the lash adjuster 84 and pressed against the swing cam surface 36 of the second swing cam arm 28R. . The variable valve operating device 140 is configured to maintain the position of the transmission arm 74 that has received the urging force from the lash adjuster 84 when the transmission arm 74 and the input arm 72 are in a non-coupled state (not shown). )).

  The valve stop mechanism 70 includes an arm coupling mechanism for coupling and releasing the input arm 72 and the transmission arm 74. Hereinafter, the configuration of the arm coupling mechanism will be described with reference to FIGS. 5 and 6.

  The input arm 72 is formed with a pin hole 88 having an opening on the transmission arm 74 side. The pin hole 88 is provided with a switching pin 90 that can be taken in and out toward the transmission arm 74. A return spring 92 is housed inside the pin hole 88 behind the switching pin 90.

  A hydraulic chamber 94 having an opening on the input arm 72 side is formed in the transmission arm 74, and a piston 96 is accommodated in the hydraulic chamber 94. The hydraulic oil is supplied to the hydraulic chamber 94 through the inside of the rocker shaft 76. When the hydraulic pressure in the hydraulic chamber 94 is increased by such a configuration, the switching pin 90 is pushed back from the hydraulic chamber 94 toward the input arm 72 by the piston 96 receiving the hydraulic pressure.

  The switching pin 90 and the pin hole 88 are arranged on the same arc centering on the rocker shaft 76, and the input arm 72 is in contact with the base circle portion 28a of the second swing cam arm 28R at both positions. It matches with the state. If the position of the switching pin 90 and the position of the pin hole 88 overlap in a state where no hydraulic pressure is applied to the piston 96 (see the valve stop mechanism 70 on the first intake valve 103L side in FIG. 6), the tip of the switching pin 90 Is inserted into the hydraulic chamber 94. As a result, the input arm 72 is coupled to the transmission arm 74. In such a coupled state, the input from the drive cam 12 transmitted to the input arm 72 is transmitted to the second intake valve 103R via the transmission arm 74. As a result, the lift operation of the second intake valve 103R is executed.

  On the other hand, when the position of the switching pin 90 and the position of the pin hole 88 overlap with each other in a state where hydraulic pressure is applied to the piston 96 (see the valve stop mechanism 70 on the second intake valve 103R side in FIG. 6), the switching pin 90 is It is pushed back to the pin hole 88 side. As a result, the coupling between the input arm 72 and the transmission arm 74 is released. In such a release state, the input arm 72 swings within a predetermined range in response to the input of the drive cams 12 and 14. However, since the input is not transmitted to the transmission arm 74, the lift operation of the second intake valve 103R enters a pause state.

  According to the valve stop mechanism 70 described above, the lift operation can be arbitrarily stopped for each intake valve 103 by switching the switching pin 90.

  The above-described ECU 130 controls the operation of the variable valve mechanism 140 in accordance with the engine operating state. Here, in particular, the operation control of the variable valve mechanism 140 when switching from the full cylinder operation to the reduced cylinder operation ( The reduced-cylinder operation switching control) will be described with reference to FIG.

  FIG. 7 shows a main flow of reduced-cylinder operation switching control executed by the ECU 130.

  In step S1, it is determined whether or not there is a reduced-cylinder operation request during all-cylinder operation.

  If there is a reduced-cylinder operation request, the process proceeds to step S2. When there is no reduced cylinder operation request, the reduced cylinder operation switching control flow is terminated.

  In step S2, the coolant temperature Tw is used as the engine temperature, and the coolant temperature Tw is compared with a predetermined lower limit temperature Ts. Here, the lower limit temperature Ts is a threshold value for determining whether or not to reduce the operating angle of the intake valve 103. In this embodiment, the cooling water temperature Tw is used as the engine temperature to determine whether or not to reduce the operating angle of the intake valve 103. In addition, the hydraulic chamber of the valve stop mechanism 70 is used as the engine temperature. Whether or not to reduce the operating angle of the intake valve 103 may be determined by using the temperature of the hydraulic oil supplied to 94.

  In step S2, if the coolant temperature Tw ≦ the lower limit temperature Ts, it is determined that the temperature is low, and the process proceeds to step S3, where the continuously variable lift valve mechanism 20 controls the intake valve 103 within a range that does not affect torque fluctuation. Reduce the working angle. Thereafter, in step S4, the valve stop mechanism 70 switches from all-cylinder operation to reduced-cylinder operation, and the reduced-cylinder operation switching control flow ends.

  On the other hand, if the cooling water temperature Tw> the lower limit temperature Ts in step S2, it is determined that the temperature is not low, the process proceeds to step S5, and the continuously variable lift valve mechanism 20 controls the intake valve 103 according to the engine operating state. Perform normal control to control the working angle. Thereafter, in step S4, the valve stop mechanism 70 switches from all-cylinder operation to reduced-cylinder operation, and the reduced-cylinder operation switching control flow ends.

  FIG. 8 is a time chart showing an example of reduced-cylinder operation switching control at low temperatures.

At time t ₁ is the closing timing of the intake valve 103, when it is determined that the reduced-cylinder operation request is present (step S1), the cylinder deactivation instruction is ON (FIG. 8 (A)). It is determined that there is a reduced cylinder operation request (step S1). Further, it is determined that the temperature is low (step S2), and control for reducing the operating angle is performed (step S3). As a result, the cam lift is changed from the large operating angle (FIG. 8C) to the small operating angle (FIG. 8D). Further, hydraulic pressure is applied to the piston 96, and the switching pin 90 starts to operate.

Conventionally, when the cam lift at low temperatures remains long duration, by the base circle section is short, at time t ₂ after the opening of the intake valve 103, the operation of the switching pin 90 at time t ₃ There was a possibility of lack of switching time to complete.

In this regard, according to the present embodiment, immediately after time t ₁ , the cam lift is changed from the large operating angle to the small operating angle at low temperatures, so that the opening timing of the intake valve 103 is changed from time t ₂ to time t ₄ . Since it is delayed, the base circle section can be taken longer.

Thus, the intake valve 103 from the operation is completed the time t ₃ of the switching pin 90 is allowed to establish the switching to the reduced-cylinder operation until time t ₄ when opened, capable of reduced-cylinder operation The operating range can be expanded to the low temperature side.

  According to the present embodiment, when the reduced-cylinder operation is requested during all-cylinder operation and the cooling water temperature Tw is equal to or lower than the predetermined lower limit temperature Ts, the operating angle is reduced by the continuously variable lift valve mechanism 20. Then, the valve stop mechanism 70 switches from full cylinder operation to reduced cylinder operation. As a result, the base circle section can be made longer at low temperatures and the time for switching to reduced-cylinder operation is ensured, so that the operating range in which reduced-cylinder operation can be performed can be expanded to the low temperature side.

  Further, according to the present embodiment, it is possible to easily determine whether or not the internal combustion engine 101 is at a low temperature based on the cooling water temperature Tw by using the cooling water temperature Tw as the engine temperature.

  In this embodiment, the internal combustion engine 101 includes the variable valve operating device 140 that changes the valve operating characteristic of the intake valve 103. In addition to this, the variable valve operating apparatus that changes the valve characteristic of the exhaust valve 104 is provided. An apparatus may be provided. As a result, when the reduced-cylinder operation is requested during all-cylinder operation and the engine temperature (cooling water temperature Tw) is equal to or lower than the predetermined lower limit temperature Ts, the action of the exhaust valve 104 by the continuously variable lift valve mechanism. After the angle is reduced, it is possible to switch from full cylinder operation to reduced cylinder operation by the valve stop mechanism.

12 First Drive Cam 14 Second Drive Cam 20 Continuously Variable Lift Valve Mechanism 22 Control Shaft 28 Swing Cam Arm 28a Base Circle 30 First Roller 32 Second Roller 36 Swing Cam Surface 36a Base Circle 36b Working Surface 40 Fixed Mechanism 44 Large lift arm 46 Input roller 50 Single valve switching mechanism 70 Valve stop mechanism 72 Input arm 74 Transmission arm 76 Rocker shaft 78 Input roller 79 Lost motion spring 82 Valve pressing part 84 Rush adjuster 88 Pin hole 90 Switching pin 101 Internal combustion engine 103 Intake valve 104 Exhaust valve 122 Intake camshaft 123 Exhaust camshaft 124 Water temperature sensor 130 ECU (electronic control unit)
140 Variable valve gear

Claims (4)

An operating cylinder switching mechanism for switching between all-cylinder operation for operating all cylinders of a multi-cylinder internal combustion engine and reduced-cylinder operation for suspending some of the cylinders;
A variable operating angle mechanism for changing the operating angle of the engine valve;
An internal combustion engine control device comprising:
When the reduced cylinder operation is requested during all cylinder operation and the engine temperature is equal to or lower than the predetermined temperature, the operation angle is reduced by the operating angle variable mechanism and then the all cylinder operation is performed by the operating cylinder switching mechanism. A control device for an internal combustion engine, characterized in that the operation is switched from a reduced cylinder operation to a reduced cylinder operation.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the operating cylinder switching mechanism stops the part of the cylinders by stopping valve operation of the part of the cylinders during the reduced cylinder operation.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the operating angle variable mechanism is a continuously variable lift valve mechanism that continuously changes an operating angle and a lift amount of the engine valve.   The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the engine temperature is a temperature of cooling water for cooling the internal combustion engine.

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