JP2005133592A - Variable valve device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fail-safe capability at the time of operation fault of an exhaust valve timing varying mechanism 40. <P>SOLUTION: The device is equipped with intake/exhaust valve timing varying mechanisms 30, 40 for varying an intake valve 18 timing and an exhaust valve timing, respectively and an intake operation angle varying mechanism 20 for varying an operation angle/valve lift amount of the intake valve. When detecting the operation fault of the exhaust valve timing varying mechanism 40, at least either of the intake valve timing varying mechanism 30 and intake operation angle varying mechanism 20 is driven and controlled so that an opening time IVO of the intake valve leads a compression upper dead point TDC. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable valve for an internal combustion engine having two valve timing variable mechanisms for making the phase of the operation center angle of the intake and exhaust valves variable and an intake operation angle variable mechanism for making the operation angle of the intake valve variable. More particularly, the present invention relates to a fail-safe technique when an exhaust valve timing variable mechanism malfunctions.

  Various variable valve mechanisms that can change the valve lift characteristics of the intake and exhaust valves have been proposed in the past in order to improve the output and fuel consumption of the internal combustion engine, clean the exhaust, and the like. For example, in Patent Document 1, in an internal combustion engine having a variable valve timing mechanism that varies the valve timing of an intake valve or an exhaust valve, when a failure related to a control system of the variable valve timing mechanism is detected, valve overlap is detected. It is forcibly reduced to ensure a certain driving performance.

  In Patent Document 2, when an abnormality of the internal combustion engine is detected, the operation of a variable operating angle mechanism that changes the valve lift amount and operating angle of the intake and exhaust valves is controlled to forcibly reduce or eliminate valve overlap. ing.

In Patent Document 3, both the intake and exhaust valves are provided with variable valve timing mechanisms that change the valve timing, and when an abnormality in one of the variable valve timing mechanisms is detected, each variable valve timing mechanism is provided with data for abnormal conditions. Use to control. For example, the valve timing variable mechanism in which an abnormality is detected is forcibly fixed at the most retarded position, and the other valve timing variable mechanism is switched to an operation map for an abnormality to control driving. Alternatively, both valve timing variable mechanisms are fixed at the most retarded position when an abnormality is detected.
JP-A-7-139378 JP 2000-130196 A JP 2003-49671 A

  In an internal combustion engine, particularly a gasoline engine, it is desirable to widely adjust the opening / closing timings of the intake / exhaust valves in accordance with the engine speed, engine load, and the like in order to improve fuel consumption, output, and exhaust purification. Therefore, both the intake and exhaust valves are provided with an intake valve timing variable mechanism that can change the phase of the operation center angle with respect to the crank angle, that is, the valve timing, and the magnitude of the intake valve operation angle (and the valve lift amount). It is preferable to use a variable intake operating angle variable mechanism in combination. In this way, in the variable valve operating apparatus for an internal combustion engine that uses both the intake / exhaust valve timing variable mechanism and the intake operating angle variable mechanism, in the event of a malfunction, including malfunction of the exhaust valve timing variable mechanism and failure such as sticking. The fail-safe property has not been considered so far, including Patent Documents 1 to 3 described above.

  For example, if the valve overlap is reduced or eliminated as in Patent Document 1 or Patent Document 2 at the time of malfunction of the exhaust valve timing variable mechanism, the valve overlap is caused particularly in an engine operation state such as a middle / high load range. The residual gas is not blown back to the intake system such as the intake port, and the fuel atomization promoting effect by this blow-back cannot be obtained, so that the combustion stability may be lowered. The present invention has been made paying attention to such a new problem.

  An internal combustion engine variable valve operating apparatus according to the present invention includes an intake valve timing variable mechanism that varies a phase of an operation center angle of an intake valve, an exhaust valve timing variable mechanism that varies a phase of an operation center angle of an exhaust valve, And an intake operation angle variable mechanism that makes the operation angle of the intake valve variable. A malfunction detecting means for detecting malfunction of the exhaust valve timing variable mechanism, and when the malfunction of the exhaust valve timing variable mechanism is detected, the opening timing of the intake valve is advanced from the top dead center; Thus, at least one of the intake valve timing variable mechanism and the intake operation angle variable mechanism is driven and controlled.

  Since two variable valve timing mechanisms that are applied to each of the intake and exhaust valves and the three variable mechanisms of the variable intake operating angle are used together, the opening and closing timing of the intake and exhaust valves can be adjusted widely according to the engine operating conditions. It is possible to effectively improve fuel consumption performance, output performance, exhaust purification performance, and the like. In such a variable valve system, when the exhaust valve timing variable mechanism does not operate properly, the valve opening timing is positively given by opening the intake valve from the top dead center. For this reason, the atomization of the fuel is promoted by blowing back to the intake system such as the intake port by the residual gas, and the combustion state can be improved / improved.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, in this internal combustion engine, a pair of intake valves 18 and a pair of exhaust valves (not shown) are provided for each cylinder. The intake valve 18 has two types of variable valve mechanisms that can change the valve lift characteristics, specifically, the phase of the operation center angle of the intake valve 18 (intake camshaft 19) with respect to the crank angle, that is, the valve timing. An intake VTC (Valve Timing Control) 30 that is a variable intake valve timing variable mechanism, and an intake VEL (Variable valve Event) that is an intake operation angle variable mechanism that can continuously change the operating angle and valve lift amount of the intake valve 18. and Lift) 20 are applied. An exhaust VTC (Valve Timing Control) 40, which is an exhaust valve timing variable mechanism capable of changing the phase of the operation center angle, that is, the valve timing of the exhaust valve, is applied to the exhaust valve.

  The intake camshaft 19 receives rotational power from the crankshaft via a pulley or sprocket, and rotates about its own axis in conjunction with the rotation of the crankshaft. A swing cam 21 that opens and closes the intake valve 18 is externally fitted and supported on the intake cam shaft 19 above the valve lifter 17 of the intake valve 18.

  The intake VEL 20 is eccentrically fixed to or integrated with the intake camshaft 19, a circular eccentric cam 23 that is eccentrically fixed to the intake camshaft 19, a control shaft 24 that extends parallel to the intake camshaft 19 in the cylinder row direction, and is eccentrically fixed to the control shaft 24. A circular control cam 25 that is integrally formed, a rocker arm 26 that is swingably fitted to the control cam 25, and a ring-shaped first cam that links one end of the rocker arm 26 and the eccentric cam 23. The link 27, the rod-shaped second link 28 that links the other end of the rocker arm 26 and the tip of the swing cam 21, and the electrically driven VEL conversion device 22 as an actuator that changes the rotation angle of the control shaft 24. And have. One end of the first link 27 is attached to the eccentric cam 23 so as to be rotatably fitted.

  When the intake camshaft 19 rotates in conjunction with the crankshaft, one end of the first link 27 fitted to the eccentric cam 23 is rotationally displaced with respect to the axial center of the intake camshaft 19, and the first link 27 is wholly As a result, the swing cam 21 swings within a predetermined swing angle range via the rocker arm 26 and the second link 28 linked to the first link 27. When the swing cam 21 pushes down the valve lifter 17, the intake valve 18 opens and closes.

  When the rotation angle of the control shaft 24 is changed by the VEL conversion device 22, the center of the control cam 25 serving as the rocking center of the rocker arm 26 is rotationally displaced with respect to the axis of the control shaft 24, and the links 27 and 28 are moved. As a result, the initial posture of the swing cam 21 (the center phase of the swing range) changes. As a result, the operation angle of the intake valve 18 and the valve lift amount continuously change while the phase of the operation center angle of the intake valve 18 with respect to the crank angle remains substantially constant.

  In such an intake VEL 20, the rocker arm 26 and the links 27 and 28 are gathered around the intake camshaft 19, so that the intake VEL 20 is compact and has excellent engine mountability. Further, since many of the connecting portions between the members are in surface contact, such as the bearing portion between the eccentric cam 23 and the first link 27 and the bearing portion between the control cam 25 and the rocker arm 26, lubrication is performed. In addition to being easy, it does not require an urging means such as a return spring and is excellent in durability and reliability. Further, since the valve layout is substantially a direct acting type, the rotation limit can be improved with a simple and compact configuration.

  The intake VTC 30 and the exhaust VTC 40 are known as disclosed in Japanese Patent Application Laid-Open No. 5-98916 and the like, and a form using a helical spline and a vane form are well known. Briefly, the intake VTC 30 is housed in the external rotator 31 including a cam pulley (or sprocket) that rotates in conjunction with the crankshaft, and rotates inside the external rotator 31 and rotates integrally with the intake camshaft 19. An internal rotary body that rotates, and the two rotary bodies are mutually rotated by a hydraulically driven intake VTC conversion device 32, so that the phase of the operation center angle (intake center angle) of the intake valve with respect to the crank angle, that is, intake air The valve timing of the valve is advanced or retarded. Similarly, the exhaust VTC 40 is provided with an external rotating body 41 including a cam pulley (or sprocket) that rotates in conjunction with the crankshaft, and a fixed cam that is housed inside the external rotating body 41 and drives an exhaust valve. The exhaust camshaft 43 and an internal rotating body that rotates integrally with the exhaust camshaft 43, and by rotating the rotating bodies with each other by the hydraulic exhaust VTC conversion device 42, the exhaust valve operating center angle (exhaust gas) with respect to the crank angle The phase of the central angle), that is, the valve timing of the exhaust valve is advanced or retarded. Although not shown, both VTCs 30 and 40 are of a hydraulic drive system using a common hydraulic pump as an operating source.

  The engine control unit 1 is a well-known digital computer having a CPU, ROM, RAM, and an input / output interface, and has a function of storing and executing various control processes as will be described later. The engine control unit 1 includes a signal 2 from a water temperature sensor, an intake air amount signal 3 from an air flow meter, a signal from a throttle sensor 4, a signal 5 from a crank angle sensor, and a signal from an oxygen sensor provided in an exhaust passage. 6, a rotation signal 7, a signal 8 from the oil temperature sensor, a signal 11 from the VEL angle detection sensor 15 that detects the rotation angle of the control shaft 24, and an intake cam angle sensor 16 that detects the rotation angle of the intake cam shaft 19 Various detection signals representing the vehicle operating state such as the signal 12 and the signal 45 from the exhaust cam angle sensor 44 that detects the rotation angle of the exhaust cam shaft 43 are input. Based on these signals, the engine control unit 1 sends control signals 9, 10, 13, 14, to various actuators such as a fuel injection device, an ignition device, a VEL conversion device 22, and intake / exhaust VTC conversion devices 32, 42, respectively. 46 is output and its operation is controlled.

  FIG. 3 is a valve timing chart showing opening / closing timings and opening / closing periods (operating angles) of the intake and exhaust valves. For example, in the high speed / high load range, in order to improve the intake charging efficiency, as shown in FIG. 3B, a region where both the intake valve and the exhaust valve are open, that is, a so-called valve overlap section BO is set large. To do. Specifically, as compared with the reference setting state shown in FIG. 3A, the phase of the exhaust center angle of the exhaust valve by the exhaust VTC 40 is set to the retard side, and the intake center angle of the intake valve by the intake VTC 30 is set. The phase is set to the advance side, and the operating angle of the intake valve by the intake VEL 20 is set to be large.

  FIG. 4 is a valve timing diagram showing opening / closing timings and valve opening periods (operating angles) of the intake / exhaust valves according to the first embodiment of the present invention, and FIG. 7 is a flow of control according to the first embodiment. It is a flowchart which shows.

  Referring to FIG. 7, first, in S (step) 11, a target conversion angle that is a target value of the intake / exhaust center angle by intake / exhaust VTCs 30, 40 is determined in accordance with the engine operating state. This target conversion angle corresponds to the target value t1 (see FIG. 2) of the phase difference between the intake and exhaust camshafts 19 and 43 with respect to the crank angle. In S12, control signals corresponding to the target conversion angles of the VTCs 30 and 40 are output to the VTC conversion devices 32 and 42, respectively, and the drive control of the VTCs 30 and 40 is performed toward the target conversion angle.

  In S13, a state in which the exhaust VTC 40 does not normally operate due to the sticking of the hydraulic conversion device 42 or the like, that is, an operation failure including an abnormality / failure of the exhaust VTC 40 is detected (operation failure detecting means). For example, based on the crank angle sensor signal 5 and the exhaust cam angle sensor signal 45, the actual conversion angle of the exhaust VTC 40 is detected and calculated, and the actual conversion angle is compared with the above-described target conversion angle. Perform detection / judgment. The actual conversion angle corresponds to the cam angle sensor signal difference t2 (see FIG. 2) with respect to the crank angle sensor signal, that is, the camshaft phase difference with respect to the crank angle. If t2 and t1 do not match and the difference exceeds a predetermined value, it is determined that the exhaust VTC 40 is malfunctioning. A warning lamp or the like may warn the driver that the exhaust VTC 40 is malfunctioning.

  If a malfunction of the exhaust VTC 40 is detected in S13, the process proceeds to S15, and target operating angles of the intake VTC 30 and the intake VEL 20 are calculated so that the intake valve opening timing IVO is advanced from the compression top dead center TDC. A specific target value calculation method differs depending on each embodiment. For example, in the first embodiment, as shown in FIG. 4, the IVO is advanced more than the TDC by changing the intake VEL 20 that is mainly electrically driven and has high responsiveness to the large operating angle / large valve lift side. Yes. In S16, a control signal corresponding to the target operating angle calculated in S15 is output to the intake VTC conversion device 32 and the VEL conversion device 22, and the intake VTC 30 and the intake VEL 20 are driven and controlled toward the target operating angle. The processing contents of S15 and S16 constitute fail-safe processing at the time of malfunction of the exhaust VTC 40, that is, fail-safe means.

  Since the exhaust valve closing timing EVC is retarded from the TDC, the intake valve opening timing IVO is advanced from the compression top dead center TDC so that the intake valve and the exhaust valve are opened simultaneously. (See FIG. 3) is positively given. In other words, in S15 and S16, the IVO is advanced from the EVC so as to positively provide valve overlap.

  As described above, when a malfunction of the exhaust VTC 40 is detected, drive control of at least one of the intake VEL 20 and the intake VTC 30 is performed to advance the IVO from the TDC, and the valve overlap BO is positively applied. Therefore, the atomization of the fuel can be promoted by blowing back the residual gas by the valve overlap BO to the intake port which is the intake system, and the combustion state can be improved. Accordingly, stable ignitability and combustibility can be obtained even when the exhaust VTC 40 is malfunctioning, and start-up failure and misfire can be avoided, so that the fail-safe property is improved.

  In particular, in the first embodiment, as shown in FIG. 4, when an operation failure of the exhaust VTC 40 is detected, the electric drive type and responsive intake VEL 20 is driven to the large operating angle / large valve lift side. As a result, the valve overlap BO is eliminated without using the hydraulically driven intake VTC 30, so that the response and reliability are excellent.

  5 and 8 are a valve timing chart and a flowchart of the second embodiment. Referring to FIG. 8, the process flow from S11 to S13 is the same as that of the first embodiment. If a malfunction of the exhaust VTC 40 is detected in S13, the process proceeds to S14, and based on the crank angle sensor signal 5 and the exhaust cam angle sensor signal 45, the malfunction position of the exhaust VTC 40, that is, the phase of the operation center angle of the exhaust valve. The exhaust center angle θ is calculated.

  In subsequent S15a, the IVO is advanced from the TDC, and the advance amount (BTDC) θ ′ of the IVO with respect to the TDC is equal to or less than the retard amount (ATDC) θ of the EVC with respect to the TDC. A target value of the intake operation angle is calculated, and a target value of the phase of the intake center angle of the intake VTC is calculated. Based on these target values, the operation control of the intake VEL 20 and the intake VTC 30 is performed (S16).

  According to the second embodiment, when the exhaust VTC 40 is malfunctioning, as in the first embodiment, a valve overlap is provided to promote fuel atomization by blowing back residual gas, thereby improving and improving the combustion state. In addition, since the advance amount θ ′ of the IVO is limited to be equal to or less than the retard amount θ of the EVC, it is possible to effectively prevent the residual gas from becoming excessive due to the excessive overlap, and the exhaust VTC 40 The combustion stability at the time of malfunction is further improved.

  6 and 9 are a valve timing chart and a flowchart of the third embodiment. The processes from S11 to S13 are the same as in the first embodiment. If an operation failure of the exhaust VTC 40 is detected in S13, the processing after S14 is executed. Note that the process of S14 (see the second embodiment) may be omitted.

  In S15b, the target value of the intake operating angle of the intake VEL 20 is calculated so that the IVO is advanced from the TDC and the IVC is approximately BDC, that is, in the vicinity of the BDC, and the phase of the intake central angle of the intake VTC is calculated. Calculate the target value. Based on these target values, the operation control of the intake VEL 20 and the intake VTC 30 is performed (S16).

  According to the third embodiment, in addition to obtaining the same effect as the first embodiment, IVC is substantially BDC, so that the combustion state can be further improved / improved by increasing the compression ratio. .

  In the first to third embodiments described above, the fail-safe process (the processes of S14 to S16 in FIGS. 7 to 9) that positively applies the valve overlap as described above in a low load region where the engine load is low. If this is done, the combustion stability may be reduced due to the blow back of the residual gas to the intake system. Therefore, preferably, in the low load range, the execution of the failsafe process described above is prohibited, that is, the operation of the failsafe means is prohibited, and the failsafe process is performed only in the middle / high load range where the engine load is relatively high. . For example, in the determination process of S13, it is also determined whether the engine load is in the middle / high load range, and only when the exhaust VTC 40 is malfunctioning and the engine load is in the middle / high load range. A fail-safe process may be executed.

  The intake VTC 30 and the exhaust VTC 40 have the same hydraulic drive system using a hydraulic pump that is a common power source. Therefore, in a situation where the malfunction of the exhaust VTC 40 is occurring, the intake VTC 30 that is the same drive method may similarly malfunction. In particular, when both the VTCs 30 and 40 are hydraulically driven as described above, problems such as clogging of the oil passage due to foreign matter in the engine oil may occur regardless of the intake side or the exhaust side. 40 can be malfunctioning. Therefore, preferably, when the exhaust VTC 40 is malfunctioning, the intake VTC 30 is fixed and held at the initial position, and only the intake VEL 20 is driven and controlled, so that the above-described fail-safe process, that is, a process of advancing at least IVO more than TDC. To do. In this case, when the exhaust VTC 40 is malfunctioning, the intake VTC 30, which is the same hydraulic drive system as the exhaust VTC 40 in which malfunction has been detected, is fixed at the initial position, so that the intake VTC cannot be satisfactorily driven and controlled. Even if it exists, valve overlap BO can be provided reliably and it is excellent in stability and reliability.

  As described above, the present invention has been described based on specific embodiments, but the present invention is not limited to these embodiments, and includes various modifications and changes without departing from the spirit of the present invention. It is a waste. For example, when the exhaust VTC is malfunctioning and in a low load range, the valve overlap is reduced and eliminated, contrary to the fail-safe process that positively applies the valve overlap described above. Thus, the combustion stability may be improved.

1 is a schematic configuration diagram showing a variable valve operating apparatus for an internal combustion engine according to the present invention. The time chart for demonstrating the malfunctioning detection of an exhaust valve timing variable mechanism. The valve timing diagram which shows the valve opening period and opening / closing timing of an intake / exhaust valve. The valve timing diagram which shows the valve opening period and opening / closing timing of the intake / exhaust valve which concerns on 1st Example of this invention. The valve timing diagram which shows the valve opening period and opening / closing timing of the intake / exhaust valve which concern on 2nd Example of this invention. The valve timing diagram which shows the valve opening period and opening / closing timing of the intake / exhaust valve which concern on 3rd Example of this invention. The flowchart which shows the flow of control which concerns on the said 1st Example. The flowchart which shows the flow of control concerning the said 2nd Example. The flowchart which shows the flow of control which concerns on the said 3rd Example.

Explanation of symbols

1 ... Engine control unit (fail-safe means)
20 ... Variable intake operating angle mechanism (intake VEL)
30 ... Intake valve timing variable mechanism (intake VTC)
40. Exhaust valve timing variable mechanism (exhaust VTC)

Claims (5)

An intake valve timing variable mechanism that makes the phase of the operation center angle of the intake valve variable;
An exhaust valve timing variable mechanism that makes the phase of the operation center angle of the exhaust valve variable;
An intake operating angle variable mechanism that makes the operating angle of the intake valve variable;
Malfunction detection means for detecting malfunction of the exhaust valve timing variable mechanism;
When the malfunction of the exhaust valve timing variable mechanism is detected, at least one of the intake valve timing variable mechanism and the intake operation angle variable mechanism is set so that the opening timing of the intake valve is advanced from the top dead center. Fail-safe means for driving control;
A variable valve operating apparatus for an internal combustion engine.   2. The internal combustion engine according to claim 1, wherein the fail-safe means sets an advance amount of the intake valve opening timing with respect to the top dead center to be equal to or less than a retard amount of the exhaust valve close timing with respect to the top dead center when the malfunction is caused. Variable valve device.   The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the fail-safe means sets the closing timing of the intake valve in the vicinity of bottom dead center at the time of the malfunction.   The variable valve operating apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein operation of the fail-safe means is prohibited in a low load range where the engine load is low. The intake valve timing variable mechanism and the exhaust valve timing variable mechanism are hydraulically driven, and the intake operating angle variable mechanism is electrically driven.
2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the fail-safe means drives and controls only the intake operation angle variable mechanism when the operation is defective.

Images