JP2009215889A - Variable valve gear for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a control range of an operation angle and a central angle as much as possible while avoiding interference between an intake valve and a piston. <P>SOLUTION: This variable valve gear has a first variable valve train for continuously expanding and contracting a lift-operation angle of the intake valve and a second variable valve train for continuously advancing and delaying the central angle, and valve lift characteristics are determined as a combination of the operation angle and the central angle. Each control range is physically restricted in a certain range, and a region on the large operation angle side and a timing advance side is restricted along a limit L2 in which interference with a piston moving trajectory is generated. In a region near the limit L2, an upper limit value of change speed to the large operation angle side and an upper limit value of change speed to the timing advance side are restricted to become small. Therefore, if an abnormality occurs, a change amount changed for a time required for abnormality detection is reduced, and the control range can be expanded to a region in the vicinity of the limit L2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine comprising a combination of a first variable valve mechanism for changing the operating angle of an intake valve or an exhaust valve of an internal combustion engine and a second variable valve mechanism for changing the central angle of the operating angle. The present invention relates to a variable valve gear.

  In order to improve fuel efficiency at low speed and low load of the internal combustion engine, ensure stable operation, and secure sufficient output by improving intake charge efficiency at high speed and high load, the operating angle of the intake valve or exhaust valve and its center Various variable valve gears that can change the angle according to the engine operating state have been proposed.

  Patent Document 1 previously proposed by the present applicant, as a variable valve operating device for an intake valve, is a first variable valve that can simultaneously increase and decrease the lift and operating angle of the intake valve simultaneously. A mechanism (lift / operating angle variable mechanism) and a second variable valve mechanism (phase variable mechanism) that continuously delays the position of the center angle of the lift, and according to the engine operating state, A technique is disclosed in which a desired valve lift characteristic is obtained by appropriately variably controlling an operating angle and a central angle thereof independently of each other.

In this way, in the variable valve operating apparatus having two variable valve mechanisms, each target value is given according to the operation state, and each variable valve mechanism is controlled along this, For example, in the case of an intake valve, if the central angle is advanced to the maximum while the operating angle is controlled to be maximized, the intake valve and the piston that are being lifted may interfere with each other near the top dead center. . Therefore, Patent Document 2 discloses that a valve timing upper limit value is set in accordance with the actual valve lift amount, and the target valve timing is limited so as not to exceed the upper limit value. The target valve lift amount is not limited, and is variably controlled over the entire range possible in the mechanism.
JP 2002-256905 A JP 2006-312943 A

  In the above-mentioned Patent Document 2, the speed of change when the valve lift amount and the valve timing change in accordance with the change in operating conditions is not particularly controlled, and therefore the upper limit value of the valve timing is limited in anticipation of a relatively large safety allowance. As a result, there is a problem that the controllable range is narrowed accordingly.

  In particular, it takes some time to detect an abnormality in the control system, such as a failure of the sensor that detects the actual control position, and take some action (for example, fixing the valve lift characteristics). In order to reliably avoid the interference between the valve and the piston, it is necessary to give a larger safety allowance. Alternatively, in order to prevent interference between the valve and the piston in the unlikely event, a deep valve recess is required on the piston crown surface.

  The present invention includes a first variable valve mechanism that can continuously increase and decrease the operating angle of an intake or exhaust valve, a second variable valve mechanism that continuously delays the central angle of the operating angle, And a variable valve device for an internal combustion engine that realizes a valve lift characteristic according to engine operating conditions by a combination of controls, and the control range of the operating angle by the first variable valve mechanism and the second The control range of the central angle by the variable valve mechanism is limited in a way that is related to each other along the combination of the operating angle and the central angle at which the valve lift characteristic that is a combination of both does not interfere with the piston trajectory. is doing. That is, if it is an intake valve, the valve lift approaches the piston movement trajectory when it is at a large operating angle and advanced angle side, so that a combination of the operating angle and the central angle that interferes with the piston movement trajectory does not occur. The control range of each large operating angle side and advanced angle side is limited in an interrelated manner, and basically, the valve lift characteristics (operating angle / center angle) that interfere with the piston movement trajectory are controlled. There is nothing.

  In the region of the combination of the operating angle and the central angle close to the limit, the upper limit value of the changing speed of the first variable valve mechanism toward the large operating angle and the piston movement trajectory of the second variable valve mechanism. At least one of the upper limit values of the change speed in the direction of approach (ie, the advance side if the intake valve is used, or the retard side if the exhaust valve) is the upper limit value of the change speed at the operating angle and the central angle away from the above limit. Limit to a relatively low value.

  That is, when the engine operating condition changes and the target operating angle and the target central angle change, the first and second variable valve mechanisms operate correspondingly, and the operating angle and the central angle change. If the change speed of the operating angle or the central angle becomes the largest (that is, the change speed upper limit value) when the operating condition changes stepwise, the upper limit value is limited to a low value near the limit. Sometimes, for the operating angle, the upper limit value of the speed of change to the large operating angle side, and for the central angle, the upper limit value of the speed of change to the advanced angle side for the intake valve and the retarded side for the exhaust valve , Is limited to a low value. As a result, the valve lift characteristics do not change suddenly in the direction of interference with the piston during a transition, and therefore it is possible to set the control range of the operating angle and the central angle without allowing an excessively large safety allowance. Become.

  As a limitation on the upper limit value of the change speed, it is desirable that the upper limit value is limited to a lower value as the limit is closer based on the operating angle and the central angle.

  According to the present invention, the interference between the valve and the piston can be avoided more reliably, and the control range of the operating angle and the central angle can be set without allowing an excessively large safety allowance. The variable range of the lift characteristic is widened, and the characteristic can be made more suitable for engine operating conditions. Further, the valve recess provided on the piston crown surface can be eliminated or made shallower.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a system configuration of an intake air amount control device for an internal combustion engine using a variable valve device according to the present invention. The internal combustion engine 1 has an intake valve 3 and an exhaust valve 4. In addition, as a valve operating device for the intake valve 3, a first variable valve mechanism (VEL) 5 capable of continuously expanding / reducing the lift / operation angle of the intake valve 3 and a central angle of the operation angle are provided. A phase variable mechanism that can be continuously delayed, that is, a second variable valve mechanism (VTC) 6 is provided. The intake passage 7 is provided with an electronically controlled throttle valve 2 whose opening degree is controlled by an actuator such as a motor. Here, the throttle valve 2 is used only for generating a slight negative pressure (for example, −50 mmHg) necessary for processing blow-by gas in the intake passage 7 and adjusting the intake air amount. Is basically performed by changing the valve lift characteristics of the intake valve 3 by the first and second variable valve mechanisms 5 and 6. That is, a substantial throttle-less operation that does not depend on the throttle valve opening for adjusting the intake air amount is realized. The first and second variable valve mechanisms 5 and 6 and the electronic control throttle valve 2 are controlled by the control unit 10.

  A fuel injection valve 8 is disposed in the intake passage 7, and an amount of fuel corresponding to the intake air amount adjusted by the intake valve 3 as described above is injected from the fuel injection valve 8. Accordingly, the output of the internal combustion engine 1 is controlled by adjusting the intake air amount by the first and second variable valve mechanisms 5 and 6.

  The control unit 10 includes an accelerator opening signal APO from an accelerator opening sensor 11 provided on an accelerator pedal operated by a driver, an engine rotation speed signal Ne from an engine rotation speed sensor 12, and an intake air amount sensor. The control unit 10 inputs the fuel injection amount, the ignition timing, the throttle valve opening, the operating angle target value, the center angle target value, etc. based on these signals. And the fuel injection valve 8, the spark plug 9, the throttle valve 2, the first and second variable valve mechanisms 5, 6, and the like are controlled.

  FIG. 2 is an explanatory diagram showing the configuration of the first and second variable valve mechanisms 5 and 6. The mechanical structure of the first variable valve mechanism 5 and the second variable valve mechanism 6 is known, and for example, the first variable valve mechanism 5 and the second variable valve mechanism 6 have the same configuration as the devices described in Patent Documents 1 and 2 described above. Yes. Therefore, only the outline will be described.

  The first variable valve mechanism 5 that variably controls the lift and operating angle includes a drive shaft 22 driven by a crankshaft of the internal combustion engine 1, a drive eccentric cam 23 fixed to the drive shaft 22, and a rotatably supported shaft. A control shaft 32, a rocker arm 26 swingably supported by a control eccentric cam 38 of the control shaft 32, and a swing cam 29 that contacts the tappet 30 of the intake valve 3. The eccentric cam 23 and the rocker arm 26 are linked by a link arm 24, and the rocker arm 26 and the swing cam 29 are linked by a link member 28.

  The rocker arm 26 is supported at its substantially central portion by the control eccentric cam 38 so as to be capable of swinging. The arm portion of the link arm 24 is linked to one end of the rocker arm 26 via a connecting pin 25. The upper end portion of the link member 28 is linked to the end portion via a connecting pin 27. The control eccentric cam 38 is eccentric from the axis of the control shaft 32, and accordingly, the rocking center of the rocker arm 26 changes according to the angular position of the control shaft 32.

  The swing cam 29 is rotatably supported by being fitted to the outer periphery of the drive shaft 22, and a lower end portion of the link member 28 is linked to an end portion extending laterally via a connecting pin 37. ing. On the lower surface of the swing cam 29, a base circle surface concentric with the drive shaft 22 and a cam surface extending in a predetermined curve from the base circle surface are continuously formed. These base circle surface and cam surface come into contact with the upper surface of the tappet 30 according to the swing position of the swing cam 29.

  The control shaft 32 is configured to rotate within a predetermined angle range by a lift / operating angle control actuator 33 provided at one end. The lift / operating angle control actuator 33 is composed of, for example, an electric motor that drives the control shaft 32 via the worm gear 35, and is controlled by a control signal from the control unit 10. The rotation angle of the control shaft 32 is detected by a control shaft sensor 34.

  According to the first variable valve mechanism 5, the lift and operating angle of the intake valve 3 are continuously expanded and reduced simultaneously according to the rotational angle position of the control shaft 32. With the change in size, the opening timing and closing timing of the intake valve 3 change substantially symmetrically. Since the magnitude of the lift / operation angle is uniquely determined by the rotational position of the control shaft 32, the actual lift / operation angle at that time is indicated by the detected value of the control shaft sensor 34.

  On the other hand, the second variable valve mechanism 6 that variably controls the center angle is configured such that the sprocket 42 provided at the front end portion of the drive shaft 22 is relative to the sprocket 42 and the drive shaft 22 within a predetermined angle range. And a phase control actuator 43 that is rotated in an automatic manner. The sprocket 42 is linked to the crankshaft via a timing chain or timing belt (not shown). The phase control actuator 43 is a hydraulic rotary actuator in the present embodiment, and the advance side hydraulic chamber and the retard side hydraulic pressure in the actuator 43 via the hydraulic control valve 44 by a control signal from the control unit 10. The hydraulic supply to the chamber is controlled. The action of the phase control actuator 43 causes the sprocket 42 and the drive shaft 22 to rotate relative to each other, thereby delaying the lift center angle in the valve lift. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The control state of the second variable valve mechanism 6 is detected by a drive shaft sensor 36 that responds to the rotational position of the drive shaft 22.

  FIG. 3 shows the valve lift characteristics of the intake valve 3 under typical operating conditions. As shown in the figure, in an extremely low load range such as an idle, the lift / operating angle is minimum and the central angle is The phase is the most retarded position. As a result, the closing time becomes the position immediately before the bottom dead center.

  In a low load region where the load is larger than an extremely low load region such as an idle (including an idle state where an auxiliary machine load is applied), the lift / operation angle is large and the center angle is an advanced position. At this time, the intake amount is controlled to a relatively small amount by advancing the intake valve closing timing.

  In the middle load range where the load further increases and the combustion becomes stable, the phase of the central angle is advanced while further increasing the lift / operation angle. The phase of the central angle is the most advanced state at a certain point in the middle load region.

  Further, at the maximum load, the second variable valve mechanism 6 is controlled so that the lift / operation angle is further expanded and the optimum valve timing is obtained. As shown in the figure, the optimum valve lift characteristic varies depending on the engine speed.

  Next, the control range of the lift / operating angle and the central angle and the limitation on the change speed upper limit value corresponding to the control range of the lift / operating angle and the central angle, which are the main parts of the present invention, will be described.

  FIG. 4 is an explanatory diagram for explaining the basic concept of the control range of the lift / working angle and the central angle, in which the horizontal axis represents the working angle (synonymous with the lift / working angle in this embodiment), and the vertical The control range is shown with the axis as the central angle. The variable range of the operating angle is determined to be within a certain range by a restriction on the mechanism of the first variable valve mechanism 5 (for example, a stopper mechanism (not shown)). Similarly, the variable range of the central angle is the second variable valve mechanism 6. Therefore, the operating angle and the central angle can be physically changed within a rectangular range in FIG. 4. However, the combination of the operating angle and the central angle which are the large operating angle and the advance angle side in the upper right part of FIG. 4 cannot actually be used because interference with the piston occurs near the top dead center. Each point on FIG. 4 individually corresponds to a specific valve lift characteristic determined from the operating angle and the central angle of the point, and therefore, a limit line that causes interference with the piston movement trajectory (in other words, interference occurs). A line that forms a boundary between the non-valve valve lift characteristics and the valve lift characteristics that cause interference can be drawn on FIG. The line L1 in FIG. 4 shows the limit at which interference occurs on the design value, but the limit in consideration of individual product variations due to dimensional tolerances and the like is the line L2 in FIG. That is, the valve lift characteristic at the upper right of the line L2 cannot be used.

  For easy understanding, FIG. 5 shows valve lift characteristics at three representative points a, b, and c in FIG. Curve P shows the piston movement trajectory. In FIG. 5, the piston movement trajectory is drawn in a form showing a change in relative distance from the valve seat surface (change according to the crank angle). Accordingly, in FIG. The vertical distance between the valve lift characteristic and the curve P corresponds to the distance between the intake valve 3 and the piston crown surface at that moment. That is, in FIG. 5, the valve lift characteristic that contacts or intersects with the curve P cannot be used. As shown in the figure, the valve lift characteristic at point a does not interfere with the piston movement trajectory P because the central angle is the most advanced position, but the operating angle is relatively small. On the contrary, the valve lift characteristic at the point c has the maximum operating angle but does not interfere with the piston movement locus P because the central angle is the most retarded position. Point b is an intermediate advance angle position, but since the operating angle is also an intermediate size, it does not interfere with the piston movement locus P. As described above, the control range of the operating angle and the central angle is limited in a mutually related manner in the portion on the large operating angle side and the advanced angle side. Note that point a corresponds approximately to the target characteristics during partial load, point b corresponds to low speed and high load, and point c corresponds to target characteristics during high speed and high load.

  Further, it can be said that the valve lift characteristic on the lower left side of the line L2 in FIG. 4 basically does not interfere with the piston movement locus P. However, the failure of the control axis sensor 34 or the drive axis sensor 36 described above or the actuator Alternatively, in order to prevent interference (collision) between the intake valve 3 and the piston even when there is any abnormality in the control system such as an abnormality in the controller 10, at least the time required for abnormality detection is taken into consideration. Therefore, it is necessary to allow for a safety fee. In other words, when the first variable valve mechanism 5 is changing in the direction of expansion of the operating angle, for example, if the control shaft sensor 34 generates an abnormal value, this abnormal value is detected and some fail-safe function (for example, During the time required until the actuator 33 is stopped (mainly the time required for detecting an abnormality), the operating angle is slightly increased. If the operating angle expansion amount associated with this detection delay is Δ1, it is necessary to set the line L3 obtained by moving the line L2 in FIG. 4 by Δ1 to the left side of the drawing as the limit of the operating angle control range. Similarly, when a failure occurs when the second variable valve mechanism 6 changes to the advance side and a fail-safe function (for example, stop of the hydraulic pressure supply to the advance side of the actuator 43) works, The advance angle of the center angle occurs depending on the time until the abnormality is detected. If the advance amount due to this detection delay is Δ2, it is necessary to set the limit of the central angle control range to the line L4 obtained by moving the line L2 in FIG. 4 by Δ2 downward. Therefore, a line L5 shown as a reference example in FIG. 4 (corresponding to a line obtained by connecting a line L3 moved leftward by Δ1 and a line L4 moved downward by Δ2 into one line) If the control range limit of the central angle is set, a collision between the intake valve 3 and the piston is avoided even in the event of an abnormality. However, if the control range of the operating angle and the central angle is set in consideration of such a large safety allowance, the range of valve lift characteristics that can be realized accordingly is narrowed.

  Therefore, in the present invention, the upper limit value of the changing speed when the operating angle and the central angle change, in particular, the changing speed in the direction in which the distance from the piston becomes smaller is limited.

  FIG. 6 is a diagram showing a limitation on the upper limit value of the rate of change of the central angle toward the advance side by the second variable valve mechanism 6. For example, the hydraulic actuator 43 of the second variable valve mechanism 6 is a spool valve type hydraulic pressure whose duty ratio is controlled for the hydraulic pressure supplied to the advance side hydraulic chamber and the retard side hydraulic chamber of the hydraulic actuator 43. The position is controlled by controlling via the control valve 44, and the rate of change to the advance side is maximized by setting the duty ratio to the advance side to the maximum value. In the region on the lower left side of the line M1 shown in FIG. 6, the upper limit value of the change speed is not particularly limited. Therefore, for example, when the operating condition changes stepwise, the center angle changes at the maximum speed at which the duty ratio becomes maximum. It should be noted that the change rate is controlled so as to optimize the drivability, fuel consumption, and the like according to various conditions at the time of transition, so that the change rate is not always the upper limit. This line M1 has a characteristic in which the above-described change Δ2 is taken into consideration with respect to the line L2 that is a limit for causing interference. In terms of the valve lift characteristic (combination of the operating angle and the central angle) on the upper right side of the line M1, the upper limit value of the changing speed of the central angle toward the advance side is limited to be relatively low. In the valve lift characteristic on the line M4 set close to the line L2, the upper limit value of the rate of change toward the advance side is, for example, 25% of the basic upper limit value in the region on the lower left side of the line M1. Become. Specifically, the limitation on the upper limit value of the change speed is realized by limiting the maximum value of the duty ratio toward the advance angle to 25% of the normal time. The degree of restriction continuously changes between the line M1 and the line M4, and the upper limit value becomes lower as the line M4 is closer. The line M2 in the figure shows a line whose upper limit is 75% of the basic upper limit, and the line M3 shows a line whose 50% is also the same. These characteristics are set in consideration of the time required for detection at the time of abnormality as described above. Note that the degree of these restrictions may be changed step by step instead of continuously. The control range of the central angle is basically the range up to the line M4. If the rate of change is reduced in this way, the amount of advance angle that changes during a certain period of time (for example, the time required for abnormality detection) becomes smaller, so even if the safety margin for the line L2 that may cause interference with the piston is small. No interference will occur.

  Since the upper limit value of the changing speed toward the retard side is not particularly limited, the maximum value of the duty ratio can be given during transition in all the valve lift characteristics of FIG.

  FIG. 7 is a diagram showing a limitation on the upper limit value of the changing speed of the operating angle toward the large operating angle by the first variable valve mechanism 5. The change speed of the operating angle correlates with the rotation speed of the actuator 33 formed of an electric motor, but the maximum value depends on the current value or voltage value applied to the actuator 33. In the region on the lower left side of the line M11 shown in FIG. 7, the upper limit value of the change speed is not particularly limited. Therefore, for example, when the operating condition changes stepwise, the center angle changes at the maximum speed determined from the rated torque or the like. As with the central angle, the change rate is controlled so that drivability, fuel consumption, and the like are optimized in accordance with various conditions during transition, and therefore the change rate is not always the upper limit. The line M11 has a characteristic in which the above-described change Δ1 is taken into consideration with respect to the line L2 that is a limit where interference occurs. In terms of valve lift characteristics (combination of operating angle and central angle) on the upper right side of the line M11, the upper limit value of the change speed of the operating angle to the large operating angle side is limited to be relatively low. . In the valve lift characteristic on the line M14 set close to the line L2, the upper limit value of the change speed toward the large operating angle is, for example, 25% of the basic upper limit value in the region on the lower left side of the line M11. It becomes. Specifically, the upper limit value of the change speed is limited by limiting the maximum value of the current value or the voltage value given to the actuator 33 to 25% of the normal time. The degree of restriction continuously changes between the line M11 and the line M14, and the closer to the line M14, the lower the upper limit value. The line M12 in the figure shows a line whose upper limit is 75% of the basic upper limit, and the line M13 shows a line whose 50% is also the same. These characteristics are set in consideration of the time required for detection at the time of abnormality as described above. Note that the degree of these restrictions may be changed step by step instead of continuously. The control range of the operating angle is basically the range up to the line M14.

  The upper limit value of the changing speed toward the small operating angle is not particularly limited.

  FIG. 6 and FIG. 7 individually show the limitation on the change rate of the central angle and the limitation on the change rate of the operating angle for the sake of easy understanding. As shown, it is done at the same time. That is, if the valve lift characteristic (operating angle + center angle) is within the range of M1 to M4 in FIG. 6 and simultaneously within the range of M11 to M14 in FIG. If the advance angle is performed, the upper limit values of both change speeds are respectively limited to a predetermined range. Further, the control range of the operating angle and the central angle finally becomes an overlapping range of the control range of the central angle in FIG. 6 and the control range of the operating angle in FIG. That is, the line L6 in which the line M1 and the line M4 are overlapped and continuous is the limit of the control range of the valve lift characteristic determined by the combination of the center angle and the operating angle.

  By limiting the upper limit value of the change speed of the central angle and the operating angle as described above, the control range can be set without giving an excessively large safety allowance to the line L2 where the intake valve 3 and the piston can interfere, Accordingly, the valve lift characteristics can be changed in a wide range. FIG. 9 shows, as an example, a comparison between the control limit line L5 shown in FIG. 4 and the control limit line L6 when the speed upper limit value is limited as shown in FIG. The control range is expanded. In order to avoid interference between the intake valve 3 and the piston, the valve recess provided on the piston crown surface can be made shallower or eliminated.

  By the way, in many cases, the time required for detecting an abnormality for the fail-safe function is determined not by real time but by a crank angle in an internal combustion engine. For example, a time corresponding to a certain crank angle is required to determine that the detection value of the sensor read at every constant crank angle is abnormal. As described above, assuming that the time required for abnormality detection is determined by the crank angle, the actual time of the unit crank angle becomes shorter as the engine rotational speed is higher, so that the abnormality can be detected early as the actual time. Accordingly, for example, the limitation of 75% to 25% of the basic upper limit value is corrected according to the rotational speed of the internal combustion engine as described above, and the upper limit value becomes lower at lower speeds and is basically at high speeds. The upper limit value may be approached. Thereby, an excessive restriction is not given in the high speed range, and the response of the change in the valve lift characteristic is increased.

  Similarly, under conditions where the engine temperature (oil temperature or cooling water temperature, etc.) is low, such as immediately after a cold start, the friction due to the viscosity of the lubricating oil increases and the hydraulic pressure itself that drives the hydraulic actuator is low. For this reason, even if a certain amount of time is required for abnormality detection, the amount of change in the operating angle or the central angle that changes during that time becomes small. Therefore, the speed upper limit value may be corrected so as to increase as the temperature decreases according to the temperature of the internal combustion engine. FIG. 10 shows, as an example, the relationship between the ON duty ratio, the operating angle or the change speed of the central angle, and the oil temperature when a hydraulic actuator is used. Even so, the rate of change decreases as the oil temperature decreases. Therefore, for example, if the appropriate upper limit value under the reference temperature T1 is 40% in accordance with the characteristics shown in FIGS. 6 to 8 described above, the ON duty ratio that provides the same change speed as the current temperature T2. (Points indicated by circles) may be obtained. Thereby, an excessive restriction is not given at a low temperature, and the responsive deterioration of the change in the valve lift characteristic is avoided.

  As mentioned above, although one Example of this invention was described, this invention is not limited to this, A various change is possible. For example, the exhaust valve can be applied in exactly the same manner only by reversing the direction of the advance angle and the retard angle. Further, the upper limit value of the change speed can be limited by various means. For example, a dedicated electromagnetic valve may be added. Further, for example, in the case of a mechanism in which either one of the operating angle and the central angle is basically slow, the upper limit value of the speed may be limited only for the other.

  Furthermore, in the above-described embodiment, an example was described in which the present invention is applied to a variable valve operating apparatus in which the lift of the valve increases and decreases with the operating angle. However, the present invention is not limited to this, for example, Japanese Patent Application Laid-Open No. 9-184406. The present invention can be applied to a variable valve device of a type that changes only an operating angle disclosed in Japanese Patent Laid-Open No. 9-268906 and other various types of variable valve devices.

  Further, in the above embodiment, the delay mainly required for detection at the time of abnormality has been described, but in the present invention, the fail-safe function is not necessarily essential, and even when the abnormality detection and the fail-safe function are not considered, for example, This is advantageous for a response delay in control when the valve lift characteristic approaches a direction in which interference with the piston occurs.

The system block diagram of the intake air amount control apparatus of the internal combustion engine using the variable valve apparatus which concerns on this invention. The perspective view which shows the outline of a 1st, 2nd variable valve mechanism. The characteristic view which shows the valve lift characteristic in a typical driving | running condition. The basic explanatory view about the control range of an operation angle and a central angle. FIG. 5 is a characteristic diagram showing valve lift characteristics at points a, b, and c in FIG. Explanatory drawing which shows the characteristic of the restriction | limiting given to the upper limit of change speed of a center angle. Explanatory drawing which shows the characteristic of the restriction | limiting given to the upper limit of the change speed of an operating angle. Explanatory drawing which shows the characteristic of a restriction | limiting which combined both the center angle and the operating angle, and the control range. FIG. 9 is an explanatory diagram showing the control range of FIG. 8 in comparison with the control range of the reference example of FIG. 5. The characteristic figure which showed the relationship between ON duty ratio, change speed, and oil temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Intake valve 5 ... 1st variable valve mechanism 6 ... 2nd variable valve mechanism 10 ... Control unit 32 ... Control shaft 33 ... Actuator for lift / operation angle control 43 ... Actuator for phase control 44 ... Hydraulic control valve

Claims (8)

A first variable valve mechanism capable of continuously increasing or decreasing the operating angle of the intake or exhaust valve, and a second variable valve mechanism for continuously delaying the central angle of the operating angle, In a variable valve operating apparatus for an internal combustion engine that realizes valve lift characteristics according to engine operating conditions by a combination of controls
The operating angle at which the valve lift characteristic composed of a combination of the control range of the operating angle by the first variable valve mechanism and the control range of the central angle by the second variable valve mechanism is a limit that does not interfere with the piston movement trajectory. Along with the combination of and center angle,
In the region of the combination of the operating angle and the central angle close to the limit, the upper limit value of the changing speed of the first variable valve mechanism toward the large operating angle and the direction of approaching the piston movement trajectory of the second variable valve mechanism A variable valve operating apparatus for an internal combustion engine, wherein at least one of the upper limit values of the change speed to the above is limited to a value relatively lower than the upper limit value of the change speed at the operating angle and the central angle away from the limit .   2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the upper limit value is limited to a lower value as it approaches the limit based on the operating angle and the central angle.   The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2, further comprising fail-safe means for detecting a control abnormality of the first and second variable valve mechanisms and performing a predetermined fail-safe process. .   4. The variable valve operating apparatus for an internal combustion engine according to claim 3, wherein the upper limit value is corrected so as to become a lower value at a lower speed in accordance with a rotational speed of the internal combustion engine.   In the configuration in which the first variable valve mechanism or the second variable valve mechanism includes a hydraulic actuator, and the hydraulic actuator is driven via a hydraulic control valve that is controlled by a duty ratio, the duty ratio 5. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the change speed upper limit value is limited by limiting a maximum value.   In the configuration in which the first variable valve mechanism or the second variable valve mechanism includes an electric actuator, the maximum value of the current value or the voltage value for driving the electric actuator is limited. The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the change speed upper limit value is limited.   The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 6, wherein the upper limit value is corrected so as to be lower at a lower temperature in accordance with the temperature of the internal combustion engine. A first variable valve mechanism capable of continuously increasing or decreasing the operating angle of the intake or exhaust valve, and a second variable valve mechanism for continuously delaying the central angle of the operating angle, In a variable valve operating apparatus for an internal combustion engine that realizes valve lift characteristics according to engine operating conditions by a combination of controls
At least one of an upper limit value of a change speed toward the large operating angle side of the first variable valve mechanism and an upper limit value of a change speed in a direction approaching the piston interference of the second variable valve mechanism,
A variable valve operating apparatus for an internal combustion engine, which is limited based on the values of the operating angle and the central angle.

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