JP4932797B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that can variably control valve lift amounts of intake valves and exhaust valves, which are engine valves, according to engine operating conditions, and can also control an intake air amount.

  As is well known, it is possible to variably control the valve lift amount of the engine valve in accordance with the engine operating state so that the engine performance can be effectively exhibited, for example, improvement of fuel consumption at low engine speed and improvement of output at high engine speed. Examples of the variable valve device are described in Patent Documents 1 and 2 below.

  In brief, the former variable valve operating device is swingably supported by a camshaft driven to rotate by a crankshaft, a rotating cam provided on the camshaft, and a support pipe different from the camshaft. An intermediate drive mechanism that drives the intake valve by having an input portion and an output portion; and an intermediate phase difference that makes the intermediate phase difference variable that makes the relative phase difference between the input portion and the output portion of the intermediate drive mechanism variable. Variable means.

The lift variable variable actuator of the intermediate phase means makes the relative phase between the swing cam and the input section variable via the control shaft of the intermediate drive mechanism, so that the intake valve lift amount and operating angle are continuously adjusted. Can be adjusted to.
JP 2001-164911 A JP 2001-263015 A

  By the way, in the conventional variable valve operating device, as described above, the lift amount of the intake valve can be variably controlled to the engine operating state by the rotation control of the control shaft of the mediation drive mechanism. Therefore, it is possible to control the intake air amount to the engine without using the throttle valve by using such a mechanism.

  In this way, if the intake air amount is controlled by such a mechanism, the throttle by the throttle is eliminated, so that no negative pressure is generated in the intake pipe, and so-called pumping loss can be greatly reduced.

  However, in order to sufficiently reduce the intake air amount by narrowing the throttle, for example, during idling of the engine, it is necessary to control the lift to a minimum lift of, for example, 0.3 to 0.4 mm. Fluctuation torque caused by the engine valve spring or the like is transmitted to the shaft to cause forward / reverse rotation fluctuations (flapping), and the minimal low lift amount varies.

  That is, as shown in FIG. 11, when the theoretical lift amount LT when there is no rotational fluctuation in the control shaft and the variation in the actual lift L when the rotational fluctuation is taken into account, as shown in FIG. Since the lift variation width ± ΔL does not change much depending on the absolute value of, the absolute value of the control lift amount itself is large even if the control shaft rotates and fluctuates (shaded line width) in the high lift range in the high rotation range and high load range. For this reason, the variation ratio ΔL / LT of the control lift amount is small, so the influence is small. However, the shift variation ratio ΔL / LT is increased as the control lift amount is shifted to a low lift region such as a low load or low rotation with a small control lift amount. Becomes larger.

  As a result, there is a risk that the intake air amount cannot be accurately controlled, and variations in the combustion cycle and variations between cylinders occur, resulting in insufficient fuel efficiency and instability of engine rotation. There is a fear.

The present invention was devised in view of a technical problem when the conventional variable valve operating device is used for intake air amount control. The invention according to claim 1 is accompanied by a change in engine operating state. A variable lift mechanism that variably controls the valve lift amount of the engine valve and the intake air amount to the engine, an intake air amount control mechanism that controls the intake air amount to the engine, and controls the operation of the variable lift mechanism and the intake air amount control mechanism And a control mechanism for
The control mechanism is configured to restrict the operation position of the variable lift mechanism in a fixed manner, and in a control state where the operation position of the variable lift mechanism is restricted by the restriction means, the intake air amount to the engine is an intake air amount. Intake control means to be controlled by a control mechanism,
The operating position restriction lift amount of the variable lift mechanism by the restriction means is lower than the basic restriction lift amount set when the engine is at a low rotation and low load and the shift position is in the D range. It is characterized in that it is controlled so as to increase at the start, while it is controlled so as to decrease at the time of cranking at the start at room temperature.

  According to the present invention, at the time of predetermined low lift control, the operating position of the variable lift mechanism is not fixed to an extremely small lift by the restricting means, but is fixedly fixed to some small lift. The above-described actual control lift variation ratio (ΔL / LT) due to the vibrations of the constituent parts is reduced, and the intake air amount is controlled by the intake air amount control mechanism, so that the intake air amount can be accurately controlled.

  As a result, it is possible to suppress the occurrence of combustion cycle variations and variations between cylinders, so that a sufficient fuel consumption effect can be obtained and engine rotation can be stabilized.

  In addition, since the operating position restriction lift amount by the variable lift mechanism is variably controlled by the restriction variable means according to the driving state of the vehicle, the cylinders can be controlled between the cylinders during the small valve lift control in each vehicle driving state. It is possible to suppress the amount of throttle that becomes a pump loss at the time of suction or to satisfy various required performances in each operation state while suppressing the influence of the variation in the valve lift.

  Hereinafter, each embodiment of the variable valve operating apparatus of the present invention will be described in detail with reference to the drawings. The variable valve operating apparatus according to this embodiment is applied to an internal combustion engine having two intake valves per cylinder.

  That is, as shown in FIG. 1, this variable valve operating apparatus supplies intake air to a combustion chamber 3 formed between a cylinder head block 1 and a cylinder head 2 of an engine via an intake port 2a of the cylinder head 2. And a pair of intake valves 6, 6 slidably provided on the cylinder head 2 via a valve guide (not shown) and urged in the valve closing direction by the spring force of the valve springs 5, 5. A variable lift mechanism 7 for continuously and variably controlling the valve lift amount of the intake valves 6 and 6 and the intake air amount to the engine in accordance with a change in the engine operating state; An intake air amount control mechanism 8 for controlling the intake air amount into the chamber 3, and a control mechanism 9 for controlling the variable lift mechanism 7 and the intake air amount control mechanism 8 according to the operating state of the vehicle including the engine operating state. I have.

  A piston 11 connected to the crankshaft 10 via a connecting rod 10a is provided in the cylinder bore 1a of the cylinder block 1 so as to be slidable up and down. An exhaust port 2b is provided on the opposite side of the cylinder head 2 from the intake port 2a, and an exhaust valve 12 for opening and closing the exhaust port 2b is urged in a closing direction via a valve spring 12a. .

  The combustion chamber 3 is provided with a combustion pressure detection sensor 41 for detecting the combustion pressure in the combustion chamber 3. The intake pipe 4 is provided with a surge tank 4a for reducing intake pulsation, and an air flow meter 37 for detecting the intake air flow rate upstream of the intake air amount control mechanism 8. The exhaust port 2b is provided with an air-fuel ratio detection sensor 42 for detecting the air-fuel ratio of the exhaust gas.

  As shown in FIGS. 1 to 4, the variable lift mechanism 7 is fixed to a hollow drive shaft 13 rotatably supported by a bearing 14 above the cylinder head 2, and press-fitted to the drive shaft 13. The drive cam 15 is supported on the outer peripheral surface of the drive shaft 13 in a swingable manner, and is in sliding contact with the upper surfaces 16a and 16a of the valve lifters 16 and 16 disposed at the upper ends of the intake valves 6 and 6, respectively. A pair of swing cams 17, 17 that open the intake valves 6, 6 and a drive cam 15 and the swing cams 17, 17 are linked to each other, and the rotational force of the drive cam 15 is controlled by the swing cams 17, 17. Transmission means 18 for transmitting as a swinging force (valve opening force), and variable means 19 for variably controlling the operating position of the transmission means 18.

  The drive shaft 13 is disposed along the longitudinal direction of the engine, and is driven from the crankshaft 10 of the engine via a driven sprocket (not shown) provided at one end, a timing chain wound around the driven sprocket, and the like. A rotational force is transmitted, and this rotational direction is set in the clockwise direction in FIG.

  The drive cam 15 is formed in a substantially annular shape, and the shaft center Y is offset from the shaft center X of the drive shaft 13 in the radial direction by a predetermined amount so that the outer peripheral surface is formed into an eccentric circular cam profile. Yes.

  Each of the rocking cams 17 has a substantially raindrop shape having the same shape as shown in FIG. 2 and is rotatably supported by the drive shaft 13 via a support hole at a substantially annular base end 20. A pin hole is formed through one end of the cam nose 21 side. Further, a cam surface 22 is formed on the lower surface of the swing cam 17, a base circle surface on the base end portion 20 side, a ramp surface extending in an arc shape from the base circle surface to the cam nose portion 21 side, and the ramp surface To the tip end side of the cam nose portion 21 and a lift surface connected to the top surface of the maximum lift, and the base circle surface, the ramp surface, the lift surface and the top surface are at the swing position of the swing cam 17. Accordingly, the upper surface 16a of each valve lifter 16 is brought into contact with a predetermined position.

  The transmission means 18 includes a rocker arm 23 disposed above the drive shaft 13, a link arm 24 linking the one end 23 a of the rocker arm 23 and the drive cam 15, the other end 23 b of the rocker arm 23, and a swing cam. 17 is provided.

  The rocker arm 23 has a cylindrical base portion at the center supported by a control cam 30 (described later) through a support hole so as to be swingable, and at one end portion 23a protruding from the outer end portion of the cylindrical base portion. The pin hole into which the pin 26 is inserted is formed so as to penetrate, while the other end portion 23b protruding from the inner end portion of the cylindrical base portion is inserted with the pin 27 connected to the one end portion 25a of the link rod 25. A pin hole is formed.

  The link arm 24 includes an annular base 24a having a relatively large diameter, and a projecting end 24b projecting at a predetermined position on the outer peripheral surface of the base 24a, and has a fitting hole at the center of the base 24a. The drive cam 15 is rotatably held therein, and a pin hole through which the pin 26 is rotatably inserted is formed in the protruding end 24b.

  Further, the link rod 25 is formed in a substantially square shape having a concave shape on the rocker arm 23 side, and both end portions 25a and 25b are provided in the respective pin holes of the other end portion 23b of the rocker arm 23 and the cam nose portion 21 of the swing cam 17. Pin insertion holes through which the ends of the press-fit pins 27 and 28 are rotatably inserted are formed.

  The variable means 19 includes a control shaft 29 that is rotatably supported by the same bearing 14 at a position above the drive shaft 13, and a control cam 30 that is fixed to the outer periphery of the control shaft 29 and serves as a swing fulcrum of the rocker arm 23. It has.

  As shown in FIG. 4, the control shaft 29 is arranged in the longitudinal direction of the engine in parallel with the drive shaft 13, and is an electric motor 34 (DC motor) that is an actuator through a worm gear mechanism 60 provided at one end. In a lift range that exceeds a small lift whose rotation is regulated by a regulating means described later, and continuously rotates to perform continuous lift control. ing.

  Further, the control cam 30 has a cylindrical shape, and as shown in FIG. 2, the position of the shaft center P1 is deviated from the shaft center P2 of the control shaft 29 by α by an amount corresponding to the thick portion 30a.

  As shown in FIG. 1, the intake air amount control mechanism 8 is constituted by a so-called butterfly type throttle valve, and rotates the disk-like throttle valve body 38 and the throttle valve body 38 forward and backward via a throttle shaft 39. And an operating mechanism (not shown) for controlling the throttle opening.

  The operation mechanism of the electric motor 34 and the intake air amount control mechanism 8 is driven and controlled by a control signal from the electronic controller 35 which is the control mechanism 9 that detects the driving state of the vehicle including the driving state of the engine. It has become.

  That is, as shown in FIG. 1, the electronic controller 35 has a crank angle sensor 36 that detects the current engine speed, a throttle opening that detects the opening of the air flow meter 37, the water temperature sensor, and the throttle valve 38. Detection sensor (feedback), accelerator opening detection sensor, potentiometer 34 for detecting the rotational position of the control shaft 29, combustion pressure sensor 41, air-fuel ratio sensor 42, and position sensor for the shift lever of the automatic transmission, Input information signals from various sensors such as position sensors that detect positions in the so-called P (parking) range, D (drive) range, N (neutral) range, and L (first speed, second speed) range. The current driving state of the vehicle is detected by a control map or calculation based on the Together and outputs a rotation drive control signal to the motor 34, and outputs a throttle opening command signal to the actuating mechanism of the inhalation volume control mechanism 8.

  That is, when the intake valve 6 or 6 is controlled by the variable lift mechanism 7 so that the valve lift amount exceeds a predetermined small valve lift in the region where the engine load is greater than or equal to the middle rotation, the electronic controller 35 The rotational position of the control shaft 29 is controlled by rotating the control shaft 29 forward and backward via the electric motor 34 according to the engine operating state. When the control shaft 29 is controlled to the small valve lift region, the electric motor 34 is controlled by a restriction circuit that is a restriction means. Thus, the rotation of the control shaft 29 is restricted to a predetermined small torque in a substantially fixed state.

  In addition, in a state where the rotation of the control shaft 29 is restricted by the restriction circuit (small valve lift state), the electronic controller 35 is supplied to the combustion chamber 3 by the intake control circuit in which the intake air amount control mechanism 8 is an intake control means. The intake air amount is controlled.

  That is, the intake air amount control mechanism 8 is controlled when the variable lift mechanism 7 controls the intake valve 6 to a small lift L1 (see FIG. 3), which will be described later, and the control shaft 29 is regulated in a fixed state by the regulation circuit. The throttle opening of the throttle valve body 38 is continuously controlled by the electronic controller 35 in this engine operating range (about 1.5 mm range), that is, during idling operation, low load or low rotation, and this regulated lift When shifting to a region exceeding the region, the throttle opening of the throttle valve body 38 is controlled to be almost fully open or large.

  Furthermore, the electronic controller 35 operates the vehicle with a restriction variable circuit which is a restriction variable means, in addition to the basic restriction lift (L1), in the restriction lift amount during the small valve lift control of the variable lift mechanism 7 by the restriction circuit. Variable control is performed according to the state.

  Hereinafter, first, normal valve lift control of the intake valves 6 and 6 by the variable lift mechanism 7 of this embodiment will be briefly described.

  For example, at the time of engine low speed and low load including idling of the engine, the control shaft 29 is rotationally driven in the clockwise direction shown in FIGS. 2 and 3 by the control signal from the controller 35 via the electric motor 34. For this reason, the control cam 30 has a shaft center P1 that moves away from the drive shaft 13 in the upward direction as shown in FIGS. The moving angle position is maintained. As a result, the pivotal support point of the rocker arm end 23b and the link rod moves upward with respect to the drive shaft 13, so that each swing cam 17 forces the cam nose 21 side through the link rod 25. As a result, the whole is rotated counterclockwise.

  Therefore, as shown in FIGS. 2 and 3, when the drive cam 15 rotates and pushes up the one end portion 23 a of the rocker arm 23 via the link arm 24, the lift amount of the rocker cam 17 and the rocking cam 17 is increased via the link rod 25. The valve lift amount L1 of the intake valves 6 and 6 is transmitted to the valve lifter 16 and becomes small as shown in FIG.

  Therefore, in such a low-speed and low-load region, the valve lift characteristics (L1) of the intake valves 6 and 6 become small as shown by the broken line in FIG. This valve lift L1 is basically set to be about 1 to 1.5 mm, which is larger than 0.3 to 0.4 mm, even if the throttle opening is reduced. This is a lift amount that can secure a considerable intake amount.

  Further, in this operating state, the throttle opening degree of the throttle valve body 38 of the intake air amount control mechanism 8 that is not influenced by the fluctuation torque of the engine is continuously controlled.

  Note that during normal temperature cranking, the lift may be controlled to be smaller than L1 (FIG. 6). In this way, the valve-starting friction at the time of cranking is lowered, so that a good increase in cranking rotation can be obtained, and then good engine startability can be obtained by performing lift increase control.

  On the other hand, when the engine operating region shifts from a low rotation / low load region to a higher middle rotation / high load region, for example, a high rotation / high load region, an opening amount of the throttle valve body 38, that is, throttle opening is controlled by a control signal from the controller 35. The amount is controlled to be almost fully opened or large, and the lift amount of the intake valve 6 is continuously controlled by the variable lift mechanism 7, thereby controlling the intake air amount to the combustion chamber 3.

  That is, the control shaft 29 is driven to rotate counterclockwise via the electric motor 34 by a control signal from the controller 35. Therefore, the control shaft 29 rotates the control cam 30 from the position shown in FIG. 3 to the counterclockwise rotation angle position, and moves the shaft center P1 (thick portion 30a) downward. For this reason, the entire rocker arm 23 is moved in the direction of the drive shaft 13 (downward), and the end 23b presses the cam nose 21 of the swing cam 17 downward via the link rod 25 to swing the rocker arm 23. The entire cam 17 is rotated clockwise by a predetermined amount.

  Therefore, the contact position of the cam surface 22 with respect to the upper surface 16a of the valve lifter 16 of the swing cam 17 moves to the right position (top surface 22d side). For this reason, when the drive cam 15 rotates and pushes up the one end portion 23a of the rocker arm 23 via the link arm 24, the lift amount with respect to the valve lifter 16, that is, the valve lift amount L2 of the intake valves 6 and 6 increases.

  Therefore, in such an operation region, the cam lift characteristic is larger than that in the low speed and low load region, the valve lift characteristic is also increased as shown by the solid line in FIG. 6, the opening timing of each intake valve 12 is advanced, and the closing timing is increased. Becomes slower. As a result, the intake charge efficiency is improved and sufficient torque / output can be secured.

  Further, during the lift control, the throttle valve body 38 is controlled to be in a fully open or large opening state, so that the pumping loss of the engine due to the throttle action of the throttle valve body 38 is greatly reduced, and a desired torque output is achieved. The fuel consumption can be improved while ensuring the above.

  Next, the control of the variable lift mechanism 7 mainly by the restriction circuit and the restriction variable circuit of the electronic controller 35 will be described with reference to the flowcharts shown in FIGS.

  First, FIG. 7 shows an example of changing the regulated lift according to the shift position of the automatic transmission. In step 1, the engine speed N and the accelerator opening amount V are read from the crank angle sensor 10 and the accelerator opening sensor.

  In step 2, it is determined based on the information signal from each of the sensors whether or not the current operating state is in the lift regulation region.

  Here, when it is determined that it is not the restricted lift region, the routine proceeds to step 3 where normal valve lift control is performed, and when it is determined that it is the restricted lift region, that is, the region should be restricted to a small lift. If it is determined, step 4 is entered. Here, the current shift position (P, N, L, D range) of the transmission is read.

In step 5, it is determined whether or not the shift position read in step 4 is in the D range. If it is determined that the shift position is in the D range, the process proceeds to step 6 and the control circuit as described above. Thus, the rotation of the control shaft 29 is regulated via the electric motor 34, and the valve lifts of the intake valves 6 and 6 are regulated almost fixedly to the predetermined regulation small lift L1. The predetermined lift L1 is not a minimal lift of 0.3 to 0.4 mm, but a lift of about 1 to 1.5 mm. The above-mentioned control lift amount variation ratio is small, combustion variation is small, and engine stability is stable. The property is good.

  Further, since the intake air amount during this period is continuously controlled by the throttle opening of the throttle valve body 38, the required intake air amount can be secured. As a result, variations in the combustion cycle and variations in the intake air amount among the cylinders are sufficiently suppressed, so that fuel consumption can be improved and engine rotation can be stabilized.

  In particular, the opening timing of the intake valves 6 and 6 is delayed by the variable lift mechanism 7 and the valve overlap with the exhaust valve is reduced, so that fuel efficiency can be improved and engine rotation can be further stabilized.

  Further, it is determined whether or not the shift position read in step 4 is in the P range in step 7, and if it is in the P range, the process proceeds to step 8, where the restriction lift is set in the case of the D range by the restriction circuit. Control is performed to a restriction lift L1a that is slightly larger than the basic restriction lift L1. This is because cold start is normally performed in the P range, but in this case, because the friction of the piston of the engine is large, the regulated lift amount is slightly increased to increase the intake air amount, and the output that overcomes the friction Control to generate torque. This makes it possible to ensure a good startability of the engine.

  On the other hand, if it is determined in step 7 that it is not in the P range, the process proceeds to step 9 where it is determined whether or not it is in the N range. Here, if it is determined that the range is the N range, the process proceeds to step 10, where the control lift L1b is controlled to be slightly smaller than L1 of the D range.

  In the case of the N range, the friction torque acting as a load on the engine is sufficiently small because the clutches and brakes of each part of the automatic transmission are released and are in a free state. Therefore, even if the regulation lift L1b is smaller than the basic regulation lift L1, it is possible to secure an intake air amount that can sufficiently cope with the small friction torque and further improve fuel efficiency. In this case, even if the variation ratio of the control lift is slightly increased, the load itself is small and the engine is not likely to become unstable.

  If it is determined in step 9 that the gear is not in the N range, the process proceeds to step 11 where it is determined whether or not the gear is in the low range (first speed to second speed). If it is determined that the low range is selected, in step 12, the control lift L1c is controlled to be slightly smaller than the basic restriction lift L1 and slightly larger than the N range restriction lift L1b.

  In the case of this low range, the engine torque is transmitted to the axle via a large reduction ratio, so that a small engine torque is sufficient for the same running resistance from the road surface. Therefore, fuel efficiency can be improved by controlling to the relatively small regulation torque L1c. Moreover, since the load itself is small, the engine is less likely to become unstable.

  In addition, it is conceivable that the intake air amount control at each shift position is performed by changing the throttle opening side instead of the control of the regulated lift. In this case, the throttle opening control pattern or control map is shifted. The position is completely changed for each position, and the control structure of the intake air amount control mechanism 8 is complicated. However, in the case of the present embodiment, the control structure is simplified because only the restriction lift is changed according to the shift position.

  In this embodiment, an example of an automatic transmission has been described. However, the present invention can also be applied to a so-called CVT or a manual transmission.

  FIG. 8 shows a variable control flowchart of a regulated lift in a vehicle in which the control target can be switched between two-wheel drive (2WD) and four-wheel drive (4WD).

  That is, first, at step 11, the engine speed N and the accelerator opening amount V are read in the same manner as described above, and at step 12, it is determined whether or not the engine operating state is in the lift regulation region. If it is determined that the region is not in the lift restriction region, the process proceeds to step 13 where normal valve lift control is performed and the process returns.

  If it is determined that the region is in the lift restriction region, the process proceeds to step 14 where the current vehicle drive control state, that is, 2WD and 4WD control signals are read. Next, in step 15, it is determined whether or not the read current drive control state is 4WD. If it is determined that it is 2WD, the process proceeds to step 16. In step 16, a control process is performed to change the restriction lift of the intake valves 6 and 6 to the basic restriction lift L 1 via the electric motor 34 and the control shaft 29. During the two-wheel drive, the drag resistance of the driving driving of the vehicle is relatively small, so that the fuel consumption can be improved by controlling the regulation torque to the normal basic torque.

  On the other hand, if it is determined in step 15 that the speed is 4WD, the process proceeds to step 17, where a control process is performed to make the regulated lift L1d slightly larger than the basic regulated lift L1. At the time of 4WD driving, since the drag resistance of driving driving is large, the torque that the engine must generate must be increased. Therefore, the driving force is ensured by controlling the large regulating lift L1d. Furthermore, since the lift becomes large, the variation rate of the lift is further reduced, so that combustion can be stabilized even if the drag resistance is large.

  FIG. 9 shows a flowchart for variably controlling the regulated lift in accordance with the cumulative travel distance of the vehicle. In step 21, the engine speed N and the accelerator opening amount V are read in the same manner. Next, in step 22, it is determined whether or not it is a lift restriction region. If it is determined that it is not a lift restriction region, normal valve lift control is performed in step 23, but if it is determined that it is a lift region, step 24 is performed. Proceed to In step 24, the current cumulative travel distance is read.

Next, in step 25, it is determined whether or not the cumulative travel distance is less than a predetermined travel distance K. If it is determined that the cumulative travel distance is less than the predetermined travel distance K, a process of controlling the regulated lift to the normal basic lift L1 is performed in step 26. .
On the other hand, if it is determined in step 25 that it is not less than that, but in step 27, the regulated lift is controlled to a lift L1e that is slightly larger than the basic lift L1.

  In general, as the cumulative mileage of the vehicle increases, the valve lift amount of the intake valves 6 and 6 changes due to changes in valve clearance over time and wear of each component of the valve mechanism. The variation in the valve lift between the cylinders increases, and this tends to cause the variation in the combustion cycle between the cylinders. As a result, engine operation is likely to become unstable, such as fluctuations in idle rotation of the engine, poor operability, and deterioration in exhaust emission performance.

  Therefore, when the cumulative travel distance of the vehicle becomes sufficiently long as described above, the lift amount of the intake valves 6 and 6 between the cylinders varies due to the control lift L1e being slightly larger as described above. Therefore, it is possible to secure good drivability.

  FIG. 10 detects engine instability from fluctuations in engine combustion pressure and controls the regulated lift. First, at step 31, the engine speed N and the accelerator opening amount V are read, and at step 32, the lift is regulated. It is determined whether or not it is an area, and if it is not a lift restriction area, normal valve lift amount control is performed at step 33.

  If it is determined that it is in the lift regulation region, the current combustion pressure is read from the combustion pressure sensor 41 in step 34, and in step 35, it is determined whether or not the variation in combustion pressure is greater than or equal to a predetermined value based on this information signal. .

  Here, if it is determined that the combustion pressure fluctuation is less than the predetermined value, the process proceeds to step 36, where a process of controlling the regulated lift amount to the normal basic regulated lift L1 is performed. On the other hand, if it is determined that the value is equal to or greater than the predetermined value, in step 37, the restriction lift L1f is controlled to be slightly larger than the basic restriction lift L1.

  Therefore, the basic regulation lift L1 can be controlled to the limit where the combustion pressure fluctuations cause the engine operation to become unstable, so that fuel efficiency can be improved, and when the combustion pressure fluctuations occur, the regulation lift L1f is largely controlled. Therefore, the variation ratio of the control lift described above can be reduced, and the instability of the engine operation can be suppressed.

  As a method for detecting the operating state of the engine, not only the combustion pressure but also the increase / decrease in engine rotation fluctuation from the crank angle sensor 10 may be detected, and the deviation of the air-fuel ratio of the exhaust gas from the air-fuel ratio sensor 42 may be detected. It is possible to detect the engine operating state indirectly by detecting.

Technical ideas other than the claims that can be grasped from the embodiment will be described below.
(A) When the control mechanism detects that the engine operating state is unstable based on the detection signal from the detection means, the control mechanism controls the increase in the restriction lift amount by the restriction variable means. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the variable valve operating apparatus is an internal combustion engine.

According to the present invention, since the regulated lift amount is only increased only when the engine operating state is unstable, it is possible to suppress variation in the actual control lift only when necessary, and when the engine operating state is stable. By reducing the intake air amount restriction by the intake air amount control mechanism from the regulated lift amount controlled to be small, the pump loss can be further reduced, and the fuel efficiency can be improved.
(B) The internal combustion engine according to claim 1, wherein the control mechanism performs control so that the restriction lift amount is increased by the restriction variable means when the cumulative travel distance of the vehicle becomes a predetermined distance or more. Variable valve gear.

In general, when the cumulative mileage of a vehicle increases, backlash occurs due to, for example, wear of each component such as a valve seat of an engine valve and a variable lift mechanism, and the valve lift amount tends to vary among the cylinders. However, in this case, according to the present invention, since the regulated lift amount is increased, the occurrence of variations among the cylinders can be effectively suppressed. In addition, the system can be simplified because control is performed only by distance.
(C) When the variable lift mechanism is in a region where the valve lift amount of the engine valve is controlled to exceed the regulated lift amount, control is performed so that the intake air amount by the intake amount control mechanism is substantially maximized, and 2. The internal combustion engine according to claim 1, wherein when the valve lift amount is controlled to a restricted lift amount by the restricting means, the intake air amount is variably controlled by the intake air amount control mechanism. Variable valve gear.

According to the present invention, when the valve lift amount is not controlled to the restricted lift amount by the restricting means but is within the control range by the variable lift means, the intake air amount control is not variable but the intake air amount control mechanism. When the valve lift amount is controlled to the restricted lift amount by the restricting means, the intake air amount control is performed only by the intake amount control mechanism. Thereby, it becomes possible to relatively control by the variable lift mechanism and the intake air amount control mechanism. In the regulated lift area, the variation ratio of the control lift is small, so the combustion fluctuation is reduced, and the pumping loss is reduced to the maximum in other areas, so that a good fuel economy can be obtained in the total area. Can do.
(D) The variable valve mechanism for an internal combustion engine according to claim 1, wherein the variable lift mechanism continuously controls a valve lift amount.
(E) The variable lift mechanism rotates in synchronization with the crankshaft of the engine, and is supported by a drive shaft provided with a drive cam on the outer periphery and a support shaft so as to be swingable. A swing cam that opens and closes the engine valve by sliding contact, a transmission means that mechanically links the drive cam and the swing cam, and a swing fulcrum of the transmission means according to the engine operating state with the control shaft. And a control means for changing the valve position of the engine valve by changing a swing fulcrum of the transmission means by the control shaft, thereby changing a contact position of the cam surface of the swing cam with respect to an upper end of the engine valve. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the lift is variably controlled.
(F) The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the intake air amount control mechanism is constituted by a throttle valve that makes a passage sectional area of the intake passage variable.
(E) The variable valve for an internal combustion engine according to claim (a), wherein the detecting means detects an unstable state of the engine by a change in the engine speed and / or a change in the air-fuel ratio of the exhaust gas. apparatus.

  The present invention is not limited to the above embodiment, and the low load region or the low rotation region, which is the small lift control region, includes a low load medium / high rotation region, and also includes a low rotation medium / high load region. In addition to the electronic circuit such as the restriction circuit, the restriction means may have any configuration such as a mechanical restriction means using a stopper pin or the like. The variable lift mechanism may be a hydraulic type.

1 is an overall schematic diagram showing one embodiment of a variable valve operating apparatus according to the present invention. It is sectional drawing which shows the variable lift mechanism with which this embodiment is provided. It is explanatory drawing which shows the effect | action at the time of the minimum valve lift control of a variable lift mechanism. It is a principal part perspective view of the variable lift mechanism provided to this embodiment. It is a control block diagram of the present invention. It is a valve timing and valve lift characteristic figure of this embodiment. It is a control flowchart figure which made the control object the shift position switching of this embodiment. It is a control flowchart figure which made control object change of two-wheel drive and four-wheel drive of vehicles. It is a control flowchart figure for which the cumulative mileage of vehicles is a control object. It is a control flowchart figure for which the combustion pressure of the engine was controlled. It is a characteristic view which shows the actual control lift amount and theoretical lift amount in the conventional variable valve gear.

Explanation of symbols

A ... Variable lift mechanism B ... Intake amount control mechanism C ... Control mechanism D ... Various detection means E ... Main control circuit F ... Restriction means G ... Intake control means H ... Restriction variable means 2 ... Cylinder head 6 ... Intake valve 7 ... Variable Lift mechanism 8 ... Intake amount control mechanism 9 ... Control mechanism 13 ... Drive shaft 15 ... Drive cam 17 ... Swing cam 18 ... Transmission means 19 ... Variable means 35 ... Electronic controller

Claims (1)

A variable lift mechanism that variably controls the valve lift amount of the engine valve and the intake air amount to the engine in accordance with a change in the engine operating state, an intake air amount control mechanism that controls the intake air amount to the engine, the variable lift mechanism and the intake air A control mechanism for controlling the operation of the quantity control mechanism,
The control mechanism is configured to restrict the operation position of the variable lift mechanism in a fixed manner, and in a control state where the operation position of the variable lift mechanism is restricted by the restriction means, the intake air amount to the engine is an intake air amount. Intake control means to be controlled by a control mechanism,
The operating position restriction lift amount of the variable lift mechanism by the restriction means is lower than the basic restriction lift amount set when the engine is at a low rotation and low load and the shift position is in the D range. A variable valve operating apparatus for an internal combustion engine, which is controlled so as to increase at the time of starting, and to decrease at the time of cranking at the start of normal temperature.

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