JP4423775B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an operating angle changing mechanism that changes an operating angle of an intake valve (hereinafter abbreviated as an intake operating angle if necessary) and a central phase of an operating angle of an intake valve (hereinafter abbreviated as an intake phase as required). And a phase change mechanism that changes the pressure control mechanism of the internal combustion engine.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 11-210424 discloses a hydraulically driven phase change mechanism using a vane. That is, this phase change mechanism includes a housing that rotates in synchronization with the crankshaft and a vane body that rotates together with a camshaft that drives the intake valve to open and close, and the housing and the vane body are rotated relative to each other by a hydraulic actuator. By moving the camshaft, the relative phase of the camshaft with respect to the crankshaft is changed to variably control the center phase (opening / closing timing) of the operating angle of the intake valve.
[0003]
Also, the camshaft phase (the central phase of the intake valve operating angle) is set to the most retarded angle position (phase) when the hydraulic pressure immediately after engine startup is very low, where the housing and vane tend to rotate relative to each other. In order to securely hold, the housing and the vane body are provided with the most retarded angle position lock pin and the lock hole which can be engaged with each other at the most retarded angle position.
[0004]
In addition, the camshaft phase is set so that the housing and the vane do not rotate relative to each other during the period from when the most retarded phase lock is released until the oil temperature rises sufficiently. An intermediate position lock pin and a lock hole are provided in each of the housing and the vane body.
[0005]
The most retarded angle position lock pin and the intermediate position lock pin are driven by hydraulic pressure supplied from a hydraulic pump driven by a crankshaft.
[0006]
[Problems to be solved by the invention]
However, in the phase change mechanism of this publication, when the engine is started, the engine hydraulic pressure from the hydraulic pump that is always supplied to the most retarded position lock pin overcomes the urging force of the spring and the most retarded position lock pin is released. Since the most retarded phase is unlocked by moving in the direction, the position of the most retarded angle from the start of the engine due to variations in oil pressure and oil viscosity due to initial / aging deterioration, etc. The period until the stop is released is likely to vary, which may adversely affect the exhaust performance.
[0007]
In particular, when the engine is started in a cold state, the increase in engine oil pressure tends to be delayed, and therefore the period until the most retarded position is released may be excessively long.
[0008]
Further, since the device of this publication is not provided with an operating angle changing mechanism for changing the operating angle of the intake valve, it is natural that the operating angle of the intake valve cannot be adjusted according to the engine operating state. .
[0009]
One object of the present invention is to improve engine performance, particularly at the time of cold start, in a configuration in which both the operating angle changing mechanism and the phase changing mechanism are applied to an intake valve.
[0010]
[Means for Solving the Problems]
Accordingly, the invention according to claim 1 is a variable valve operating apparatus for an internal combustion engine having an operating angle changing mechanism that changes the operating angle of the intake valve and a phase changing mechanism that changes the center phase of the operating angle of the intake valve. The first holding means for holding the center phase at the most retarded angle phase, and the center phase at the retarded phase after the warm-up which is advanced from the most retarded phase at least in the idle region after the warm-up. A second holding unit that detects the engine temperature or an elapsed time after starting the engine, and at the time of cold start, the first holding unit holds the center phase at the most retarded phase. At the same time, when the engine temperature or the elapsed time after the engine start becomes a predetermined reference value or more, the holding of the most retarded phase by the first holding means is released.
[0011]
Also , At the time of cold start with the phase detection means for detecting the center phase and being held in the retarded phase after warm-up by the second holding means, before the fuel injection is started, the second It is characterized in that holding of the retarded phase after warm-up by the holding means is released and the center phase is retarded toward the most retarded phase by the phase changing mechanism.
[0012]
More The fuel injection is prohibited until the arrival of the center phase at the most retarded angle phase is detected or predicted.
[0013]
Claim 2 The invention according to the present invention is characterized in that the ignition timing is advanced in accordance with the advancement of the center phase at least during the transition from the most retarded phase to the delayed phase after warm-up.
[0014]
Claim 3 The invention according to claim is characterized in that the phase changing mechanism is electrically operated.
[0015]
Claim 4 The invention according to claim is characterized in that the phase changing mechanism is hydraulically driven.
[0016]
Claim 5 In the invention according to the first aspect, the phase changing mechanism includes a first rotating body that rotates in synchronization with the crankshaft, a second rotating body that rotates together with an intake drive shaft that opens and closes the intake valve, and a first rotating body that corresponds to the supply hydraulic pressure. Hydraulic driving means for relatively rotating the first rotating body and the second rotating body, and each of the first holding means and the second holding means includes the first rotating body and An engagement pin provided on one side of the second rotary body and driven according to the supply hydraulic pressure, and provided on the other of the first rotary body and the second rotary body, and engageable with the engagement pin It has an engagement hole and a hydraulic control valve for switching the hydraulic pressure supplied to the engagement pin.
[0017]
Claim 6 The invention according to the above is characterized in that the hydraulic pump for supplying hydraulic pressure to the engaging pin of the second holding means is driven by an external power source.
[0018]
Claim 7 The invention according to the present invention is characterized in that, at the time of cold start, the second holding means can be switched from the holding state of the retarded phase after warming up to the holding releasing state.
[0019]
Claim 8 The invention according to the present invention is characterized in that the operating angle of the intake valve is set to the minimum operating angle by the operating angle changing mechanism at least in the state where the phase is held at the most retarded angle phase.
[0020]
【The invention's effect】
According to the first aspect of the present invention, in the configuration in which both the operating angle changing mechanism and the phase changing mechanism are applied to the intake valve, the air intake operating angle is maintained at the most retarded angle phase when the cold engine is started. The valve opening timing can be stably maintained in a state delayed from the top dead center. As a result, the intake valve opens after the inside of the cylinder becomes negative pressure, fuel atomization is promoted by enhancing gas flow, combustion performance is improved, ignition timing is retarded, and exhaust performance is improved. Etc. can be achieved.
[0021]
Then, at the time of cold start, when the engine temperature or the elapsed time after the engine start becomes equal to or greater than a predetermined reference value, the configuration in which the holding of the most retarded phase by the first holding means is canceled is described above. Compared to the configuration in which the retention of the most retarded angle phase is released according to the engine oil pressure as in the above device, variation due to initial deterioration or the like is suppressed, and as a result, exhaust performance at the time of cold start is improved.
[0022]
Further, in the idle region after warm-up, the center phase is held at the delayed phase after warm-up that is advanced from the most retarded phase, so that the pump loss can be mainly reduced.
[0023]
Furthermore, When the engine is started in a cold state that is held in the retarded phase after warming up by the second holding means, the holding of the retarded phase after warming up is canceled during cranking before fuel injection. To delay the intermediate phase to the most retarded phase. And Since the fuel injection is not performed until the most retarded phase is reached, there is no risk that the fuel will be injected out of the most retarded phase at the time of cold start, and it is possible to reliably prevent a decrease in drivability due to this. .
[0024]
Claim 2 According to the invention according to FIG. 9, as shown in FIG. 9, at the time of transition from the most retarded phase to the retarded retarded phase, the gas flow is strengthened and the fuel atomization is promoted along with the advance of the intake phase. The phase of the ignition timing is advanced in a commensurate manner, and exhaust performance such as an increase in exhaust temperature can be effectively improved without deteriorating combustion stability.
[0025]
Claim 3 According to the present invention, since the phase change mechanism is electrically operated, the phase change mechanism reliably and quickly changes and holds the intake phase even when the engine oil pressure is very low, such as during cold start. It becomes possible. In other words, when the cold engine is started, the intake phase is quickly shifted to the most retarded angle phase and is maintained at this most retarded angle phase, and when the engine temperature or the elapsed time after the engine start exceeds a predetermined reference value, The phase can be rapidly advanced.
[0026]
Claim 4,5 According to the invention, the phase change mechanism is hydraulically driven, so that the structure is simplified and the cost can be reduced. That is, it is possible to improve the exhaust performance at the time of cold start with an inexpensive and simple phase change mechanism.
[0027]
Claim 6,7 According to the invention according to the present invention, it is a hydraulic drive type simple-structure phase change mechanism, but during cranking before starting fuel injection at the time of cold start in the state of being held in the retarded phase after warm-up. Even in such a case, it is possible to quickly release the hold state of the retarded phase after warming up and retard the intake phase toward the most retarded phase.
[0028]
Claim 8 According to the invention, since the intake valve is set to the most retarded phase and the minimum operating angle at the time of cold start, the gas flow effect by minimizing the operating angle can be used even after the intake valve is opened, and the operation is performed. By minimizing the angle, the closing timing of the intake valve is appropriately advanced, the effective compression ratio is increased, combustion stability is improved, and exhaust performance can be further improved.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0030]
FIG. 1 shows a variable valve operating apparatus according to a first embodiment of the present invention. Each cylinder is provided with a pair of intake valves 2. A hollow intake drive shaft 3 extends in the cylinder row direction above the intake valves 2. A swing cam 4 that contacts the valve lifter 2a of the intake valve 2 and opens and closes the intake valve 2 is fitted on the intake drive shaft 3 so as to be relatively rotatable.
[0031]
The operating angle and valve lift amount of the intake valve 2 are continuously set between the intake drive shaft 3 and the swing cam 4 while the central phase (intake phase) of the operating angle of the intake valve 2 is substantially constant. An operating angle changing mechanism 10 to be changed is provided. Further, a phase changing mechanism 20 that continuously changes the intake phase by changing the phase of the intake drive shaft 3 with respect to a crankshaft (not shown) is disposed at one end of the intake drive shaft 3.
[0032]
As shown in FIG. 2, the operating angle changing mechanism 10 includes a drive cam 11 that is eccentrically provided on the intake drive shaft 3, a ring-shaped link 12 that is externally fitted to the drive cam 11 so as to be relatively rotatable, and an intake drive shaft. 3, a control shaft 13 that extends substantially parallel to the cylinder row direction, a control cam 14 that is eccentrically provided on the control shaft 13, and a control cam 14 that is fitted on the control cam 14 so as to be relatively rotatable. And a rod-like link 16 connected to the other end of the rocker arm 15 and the swing cam 4.
[0033]
The control shaft 13 is driven to rotate within a predetermined control range via the gear train 18 by the electric actuator 17. The ECU 30 as an engine control unit includes an angle of the intake drive shaft 3 and the control shaft 13 detected by the angle detection sensors 31 and 32, a crank angle detected or estimated by various sensors, an engine speed, a load, and a water temperature. In addition to performing general engine control such as fuel injection and ignition timing control based on the engine operating conditions such as the above, the electric actuator 17 is driven and controlled, and the phase changing mechanism 20 described later is driven and controlled, and the intake valve 2 Controls opening and closing timing and operating angle.
[0034]
With the above configuration, when the intake drive shaft 3 rotates in conjunction with the crankshaft, the ring-shaped link 12 moves substantially in translation through the drive cam 11 and the rocker arm 15 swings around the axis of the control cam 14. Then, the swing cam 4 swings via the rod-shaped link 16 and the intake valve 2 is driven to open and close.
[0035]
Further, by changing the rotation angle of the control shaft 13, the axial center position of the control cam 14 that becomes the swing center of the rocker arm 15 is changed, and the posture of the swing cam 4 is changed. Thereby, the operating angle (opening / closing period) and the valve lift amount of the intake valve 2 continuously change while the intake phase remains substantially constant.
[0036]
In such an operating angle changing mechanism 10, since the connecting portions of the members such as the bearing portion of the drive cam 11 and the bearing portion of the control cam 14 are in surface contact, lubrication is easy and durability and reliability are improved. While being excellent, the resistance at the time of changing an operating angle is also suppressed low. In addition, since the swing cam 4 that drives the intake valve 2 is arranged coaxially with the intake drive shaft 3, for example, the swing cam is supported by another support shaft different from the intake drive shaft 3. In comparison, the control accuracy is excellent, the device itself is compact, and the vehicle mountability is good.
[0037]
FIG. 3 shows an electric phase change mechanism 20. The configuration of the phase changing mechanism 20 is known as disclosed in Japanese Patent Application Laid-Open No. 10-153105. Briefly, the first rotating body 21 that rotates in synchronization with the crankshaft, the intake air, Between the 2nd rotary body 22 rotated with the drive shaft 3, the cyclic | annular piston 23 meshed with both 21 and 22 via the helical spline is interposed. Then, by driving the piston 23 in the axial direction by the electromagnetic solenoid 24, the relative phase of the rotating bodies 21 and 22 changes, and the phase of the intake drive shaft 3 with respect to the crankshaft is variably controlled. The electromagnetic solenoid 24 is driven and controlled according to the engine operating state by the control signal from the ECU 30 described above.
[0038]
Next, a setting example of the intake operation angle and the intake phase according to the present embodiment will be described with reference to FIG. Note that the value of the intake phase to be described later has a relationship of P1 <P2 <P3 <P4 <P5 when the advance side is positive.
[0039]
In the idling range (a1), which is an extremely low load range including a no-load state when the engine temperature is equal to or lower than a predetermined temperature as in the cold start, the operating angle of the intake valve 2 is set by the operating angle changing mechanism 10. In addition to the minimum operating angle, the phase change mechanism 20 sets and holds the intake phase at the most retarded angle phase P1. That is, at the time of such cold start, the minimum operating angle and the most retarded angle phase P1 as described above are used as the IVO in order to purify the exhaust gas and increase the exhaust temperature accompanying the promotion of the warm-up of the catalyst and the improvement of the combustion. (Intake opening timing) is most retarded. As a result, the gas flow is strengthened by minimizing the operating angle, and the intake valve is opened after the in-cylinder negative pressure is sufficiently developed by retarding the IVO, so that the gas flow at the opening timing of the intake valve is reduced. Intensified, fuel atomization is promoted.
[0040]
On the other hand, in the idle range (a2) after warm-up, the operating angle of the intake valve 2 is set to the minimum operating angle by the operating angle changing mechanism 10, and the intake phase is set to be greater than the most retarded angle phase P1 by the phase changing mechanism 20. It is set and held at a predetermined retarded phase P2 after warm-up. In other words, reduction of residual gas and reduction of pump loss (pump loss by opening the intake valve after the piston is displaced to some extent and the cylinder becomes negative pressure without exposing the upper surface of the piston to the intake negative pressure from top dead center. The intake valve opening timing is after top dead center, and the intake valve closing timing is close to bottom dead center mainly to improve combustion. Furthermore, friction reduction and gas flow enhancement are mainly performed. In order to promote the atomization of fuel by the intake air, the intake operating angle is set to the minimum operating angle. As a result, fuel efficiency and exhaust performance can be improved in the idle region (a2) after warm-up.
[0041]
In the middle load range (c) after warm-up, the intake valve opening timing is set to before the top dead center in order to reduce the pump loss due to the increase in residual gas and improve the combustion due to the high temperature residual gas. In order to reduce the pump loss mainly by reducing the intake air intake amount (filling efficiency), it is desirable to set the intake valve closing timing before the bottom dead center. Therefore, the operating angle of the intake valve is set to a predetermined small operating angle larger than the minimum operating angle by the operating angle changing mechanism 10 with respect to the idle region (a2) after the warming-up, and the phase changing mechanism 20 Let the intake phase be the most advanced angle phase P5.
[0042]
Further, in the low load region (b) after warm-up where the required intake air amount is smaller than the medium load region (c), the operation of the intake valve 2 is mainly performed for the purpose of preventing deterioration of combustion and reducing the residual gas amount. The angle is set to a value between the minimum operating angle and the small operating angle, and the intake phase is set to a predetermined advance angle phase P4 to improve the fuel efficiency by reducing the pump loss by the effective compression ratio.
[0043]
In the fully open areas (d) to (f) after warm-up, the intake phase is set in the vicinity of the predetermined intermediate phase P3, and the operating angle is increased as the engine speed increases, thereby improving the charging efficiency. . For example, in the low rotation range (d), the IVO is advanced slightly from the top dead center, and the IVC is set slightly retarded from the bottom dead center.
[0044]
In addition, although the valve lift characteristics at the time of cooling other than idling are not specified, for example, the lift characteristics in the low / medium load region at the time of cooling are the same as the lift characteristics (b) and (c) after the warm-up described above. If it is set, combustion may be deteriorated. For example, it is necessary to make the lift characteristic (d) substantially the same as the low speed fully open region after warm-up.
[0045]
Next, a second embodiment will be described. As shown in FIGS. 5 to 7, the second embodiment is a hydraulic drive type phase change mechanism capable of realizing the electric phase change mechanism 20 of the first embodiment shown in FIG. It is different from the first embodiment in that it is 40. Other configurations are substantially the same as those of the first embodiment, and the same portions are denoted by the same reference numerals, and redundant description is appropriately omitted.
[0046]
The hydraulic drive type phase changing mechanism 40 basically has the same configuration as that described in the above Japanese Patent Laid-Open No. 11-210424. Briefly, the phase change mechanism 40 includes a housing 41 as a first rotating body that rotates in synchronization with the crankshaft, a vane body 42 as a second rotating body that rotates integrally with the intake drive shaft 3, have. The inside of the housing 41 is divided into a plurality of compartments by partition walls 43, and each compartment is divided into an advance side hydraulic chamber 45 and a retard side hydraulic chamber 46 by a vane 44 of the vane body 42. .
[0047]
The advance hydraulic chamber 45 and the retard hydraulic chamber 46 are supplied with engine hydraulic pressure from a hydraulic pump 47 as a hydraulic source driven by a crankshaft. A hydraulic control valve 48 is provided in the hydraulic passage between the hydraulic pump 47 and the hydraulic chambers 45 and 46. The hydraulic control valve 48 switches and controls the hydraulic pressure supplied to the hydraulic chambers 45 and 46 based on the control signal from the ECU 30, thereby changing the relative rotational position between the housing 41 and the vane body 42. Thus, the phase of the intake drive shaft 3 with respect to the crankshaft changes, and the intake phase is variably controlled.
[0048]
In such a hydraulic phase change mechanism 40, when the engine speed and the engine oil pressure are very low, such as when the engine is started, the vane 44 is caused by torque fluctuation caused by a valve spring reaction force or the like. There is a risk that the housing 41 may turn carelessly and generate noise. Therefore, as shown in FIGS. 5 and 6, the first holding mechanism 50 that mechanically locks and holds the intake phase at the most retarded phase P1 and a predetermined warming angle advanced from the most retarded phase. And a second holding mechanism 60 that mechanically locks and holds the after-retard retardation phase P2.
[0049]
As shown in FIG. 7, each holding mechanism 50, 60 has engagement pins 51, 61 and engagement holes 52, 62 that are engaged with each other during the most retarded phase P 1 or the warm-up retarded phase P 2. The vane 44 and the housing 41 are provided respectively. The engagement pins 51 and 61 are always urged in the fitting direction (downward in FIG. 7) by the springs 53 and 63, respectively, and hydraulic pumps 55 and 65 introduced through the hydraulic passages 54 and 64, respectively. When the hydraulic pressure from the upper side exceeds a predetermined pressure, the holding state can be released by detaching from the engagement holes 52 and 62 against the urging force of the springs 53 and 63. The hydraulic pressure introduced into the hydraulic passages 54 and 64 is switched and controlled by hydraulic control valves 56 and 66, respectively. The hydraulic control valves 56 and 66 are controlled according to the engine operating state by the control signal from the ECU 30 described above.
[0050]
Here, as will be described later, at least the second holding mechanism 60 is provided so that the held state of the retarded phase P2 after warm-up can be reliably released even in a state where the engine hydraulic pressure is substantially zero, such as at the time of cold start. The second hydraulic pump 65 is a hydraulic pump driven by an external power source such as a motor. Similarly, the first hydraulic pump 55 of the first holding mechanism 50 is preferably of a type having an external power source like the hydraulic pump 65 described above.
[0051]
Next, the operation of the second embodiment will be described with reference to FIG. Basically, the opening and closing timing of the intake valve 2 is controlled as in the first embodiment. That is, when the engine is started in the cold state (a1), it is difficult to atomize the fuel and the HC emission amount is likely to increase. Also, since the combustion state is not so good when cold, the ignition timing cannot be retarded sufficiently and the exhaust temperature is difficult to increase. Therefore, the operating angle change mechanism 10 sets the operating angle of the intake valve to the minimum operating angle, and the first holding mechanism 50 holds the intake phase at the most retarded angle phase P1. As a result, the intake valve opening timing is retarded, the inside of the cylinder becomes negative pressure as the piston descends, and fuel adhering to the valve is appropriately blown off when the intake valve is opened, thereby promoting fuel atomization. Further, by setting the minimum operating angle, the in-cylinder gas flow is enhanced and combustion is improved. Furthermore, by minimizing the operating angle, the closing timing of the intake valve is not excessively delayed, and a sufficient effective compression ratio can be ensured.
[0052]
On the other hand, in the idle region (a2) after warm-up, although the combustion is improved as described above by setting the minimum operating angle by the operating angle changing mechanism 10, the intake phase becomes the most retarded phase P1. If this is the case, the period during which the piston is exposed to negative pressure becomes longer, which may increase pump loss and lead to deterioration of fuel consumption. For this reason, in the idle region after warming up, the second holding mechanism 60 holds the intake phase at the retarded phase P2 after warming up.
[0053]
As described above, in the first and second embodiments, for example, based on the engine temperature, it is determined whether the engine is cold or after warm-up, and when the engine is cold, the intake phase is quickly adjusted to mainly improve exhaust performance. Is held at the most retarded phase P1. The engine temperature is obtained from a sensor that detects a water temperature, an oil temperature, or a catalyst activation state, or simply estimated from an elapsed time after starting.
[0054]
Further, the phase change mechanisms 20 and 40 may be of an ON-OFF type two-position switching type, but are continuously controlled (duty control) according to the engine temperature, the elapsed time after starting, or the like. Further, it is possible to finely adjust the intake phase in accordance with the engine operating conditions. For example, the fuel consumption can be further improved by minimizing the pump loss.
[0055]
Depending on engine operating conditions, the engine may be stopped after warming up and restarted in a cold state. In this case, the engine is stopped in a state in which the intake phase is held at the retarded phase P2 after warming up, and fuel injection is performed at the time of cold start in the state held in the retarded phase phase P2 after warming up in this way. In this case, a sufficient exhaust purification effect cannot be obtained.
[0056]
Therefore, in the first embodiment, during the cranking, that is, before the fuel injection is started after the ignition switch is detected to be on, the electric phase change mechanism 20 holds the retarded phase P2 after the warm-up. And the intake phase is immediately shifted to the most retarded phase P1. Then, when the arrival of the intake phase to the most retarded angle phase P1 is confirmed or predicted, the fuel injection and ignition timing control are started. As a result, there is no possibility that combustion is performed in a state in which the intake phase deviates from the most retarded phase P1 after the start of the cold engine, and it is possible to reliably prevent the exhaust performance from being deteriorated due to this.
[0057]
Further, the same effect can be obtained even when an inexpensive hydraulically driven phase change mechanism 40 is used as in the second embodiment. That is, at the time of cold start with the second holding mechanism 60 held at the retarded phase P2 after warming up, the retarded phase after warming up by the second holding mechanism 60 during cranking before starting fuel injection. The holding state of P2 is released, and the intake phase is quickly shifted to the most retarded phase P1. Thereby, there is no possibility that combustion is performed in a state deviating from the most retarded phase P1 at the time of cold start, and it is possible to reliably prevent the exhaust performance from being deteriorated due to this. Thus, as described above, the hydraulic pump 65 of the second holding mechanism 60 is turned off so that the second holding mechanism 60 can quickly release the holding state of the retarded phase P2 after the warm-up, even at the time of cold start. It is configured to be driven by an external electric motor.
[0058]
The flow of control at the time of starting the engine will be described in further detail with reference to the flowchart of FIG. When cranking is started in S (step) 1, the process proceeds to S2, and it is determined whether or not the engine is in a cold state based on the engine temperature or the like. If it is determined that the state is after warm-up, the routine proceeds to S3, where normal control (normal control of the intake operation angle and intake phase, control of fuel injection, ignition timing, etc.) is performed. On the other hand, if it is determined that the engine is cold, the process proceeds to S4, and it is determined whether the intake phase has substantially reached the most retarded phase P1. If it is determined that the most retarded phase P1 has not been reached, the process proceeds to S5. 20 and 40 shift the intake phase to the most retarded phase P1. Then, when the arrival at the most retarded phase P1 is confirmed or predicted, the process proceeds from S4 to S6, and fuel injection and ignition timing control are started. That is, fuel injection is prohibited until reaching the most retarded phase P1 is detected (confirmed) or predicted.
[0059]
In subsequent S7, it is determined whether the warm-up operation is completed. More specifically, it is determined whether the elapsed time from the substantial engine start by fuel injection or the engine temperature is equal to or higher than a predetermined reference value. If it is less than the reference value, the process proceeds to S8, and the holding state of the most retarded phase P1 is continued. When it becomes equal to or greater than the reference value, the process proceeds from S7 to S9, the holding state of the most retarded phase P1 is released, and the intake phase is advanced toward the retarded phase P2 after warming up by the phase change mechanisms 20 and 40. Let
[0060]
As mentioned above, although this invention was demonstrated based on specific embodiment, this invention is not limited to the said embodiment. For example, in the second embodiment, the second holding mechanism 60 is driven by a hydraulic pump having an external electric motor, but the engaging pin 61 of the second holding mechanism 60 can be directly driven by an external power source. Almost the same effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a variable valve gear according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an operating angle changing mechanism.
FIG. 3 is a cross-sectional view showing an electric phase change mechanism.
FIG. 4 is an operation explanatory diagram of the first and second embodiments.
FIG. 5 is a schematic perspective view showing a variable valve gear according to a second embodiment of the present invention.
FIG. 6 is a configuration diagram showing a hydraulic phase change mechanism.
FIG. 7 is a cross-sectional view showing a holding mechanism of a hydraulic phase change mechanism.
FIG. 8 is a flowchart showing a flow of control at the time of engine start.
FIG. 9 is a characteristic diagram showing the relationship between the intake phase and the ignition timing.
[Explanation of symbols]
2 ... Intake valve
3 ... Intake drive shaft
10 ... Working angle change mechanism
20 ... Phase change mechanism
21 ... 1st rotating body
22 ... Second rotating body
40: Phase change mechanism
41. Housing (first rotating body)
42 ... Vane body (second rotating body)

Claims (8)

In a variable valve operating apparatus for an internal combustion engine, comprising: an operating angle changing mechanism that changes the operating angle of the intake valve; and a phase changing mechanism that changes the center phase of the operating angle of the intake valve.
First holding means for holding the center phase at the most retarded angle phase;
A second holding means for holding the center phase at a delayed phase after warm-up that is advanced from the most retarded phase at least in an idle region after warm-up;
Detection means for detecting the engine temperature or the elapsed time after engine start;
Phase detection means for detecting the center phase ,
At the time of cold start, the first holding means holds the center phase at the most retarded angle phase, and when the engine temperature or the elapsed time after the engine start becomes equal to or greater than a predetermined reference value, Release the holding of the most retarded phase by the holding means ,
Further, at the time of cold start in a state where the second holding means holds the retarded phase after warming up, the retarded phase after warming up is held by the second holding means before starting fuel injection. And the phase change mechanism retards the center phase toward the most retarded phase, and prohibits fuel injection until the arrival of the center phase at the most retarded phase is detected or predicted. A variable valve operating apparatus for an internal combustion engine. 2. The variable motion of an internal combustion engine according to claim 1 , wherein at least at the time of transition from the most retarded phase to the retarded phase after warm-up, the ignition timing is advanced according to advancement of the center phase. Valve device. The variable valve operating apparatus for an internal combustion engine according to claim 1 or 2 , wherein the phase changing mechanism is electrically operated. 3. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the phase change mechanism is a hydraulic drive type. A first rotating body that rotates in synchronization with the crankshaft; a second rotating body that rotates together with an intake drive shaft that opens and closes an intake valve; and Hydraulic drive means for relatively rotating the second rotating body,
Each of the first holding means and the second holding means is provided on one of the first rotating body and the second rotating body, and is driven according to supply hydraulic pressure. An engagement hole provided in the other of the rotating body and the second rotating body and capable of engaging with the engaging pin, and a hydraulic control valve that switches a hydraulic pressure supplied to the engaging pin. The variable valve operating apparatus for an internal combustion engine according to claim 4 . 6. The variable valve operating apparatus for an internal combustion engine according to claim 5 , wherein the hydraulic pump that supplies hydraulic pressure to the engagement pin of the second holding means is driven by an external power source. 7. The internal combustion engine according to claim 4 , wherein when the engine is cold-started, the second holding means can switch from the holding state of the retarded phase after warm-up to the holding-released state. Variable valve gear. The internal combustion engine according to any one of claims 1 to 7 , wherein the operating angle of the intake valve is set to a minimum operating angle by the operating angle changing mechanism at least in a state in which the phase is held at the most retarded angle phase. Variable valve gear for engine.

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