JP2004301101A - Adjustable valve mechanism of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely prevent a valve lift changing mechanism 13 and a valve timing changing mechanism 17 from lowering in action responsiveness owing to rising in oil temperature or lowering in oil pressure. <P>SOLUTION: The mechanism is provided with the valve lift mechanism (VVL) 13 for gradually changing the valve lift amount of a suction valve and the valve timing changing mechanism (VTC) 17 for continuously changing the valve timing of the suction valve 15. When oil pressure of an oil pump 31 is lower than the set oil pressure or oil temperature is higher than the set oil temperature in an operating range to operate both VVL13 and VTC17, oil pressure supply from a VVL solenoid 11 to VVL13 is prohibited. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable valve operating apparatus for an internal combustion engine having two or more variable valve operating mechanisms that can be operated by hydraulic pressure of hydraulic oil to change a valve lift characteristic of an intake valve or an exhaust valve of the internal combustion engine.
[0002]
[Prior art]
Patent Literature 1 discloses a variable valve mechanism capable of changing the valve lift characteristics of an intake valve or an exhaust valve of an internal combustion engine by operating with the oil pressure of a lubricating oil as a hydraulic oil. An apparatus using both a valve lift changing mechanism for switching the valve timing and a valve timing changing mechanism for continuously changing the valve timing is disclosed. This device can vary the valve lift, and at the same time, can continuously adjust the valve timing, so that the valve lift characteristics required under each operating condition can be well adapted.
[0003]
Further, in Patent Document 1, while the oil temperature of the hydraulic oil is low, such as during a warm-up operation, the supply of hydraulic pressure to both the valve timing change mechanism and the valve lift change mechanism is prohibited, and thereafter the oil temperature rises In order to prevent a transient drop in oil pressure, a valve lift change mechanism that permits the supply of oil pressure to the valve timing change mechanism that can continuously adjust the valve timing first, and then switches the valve lift in stages Oil pressure supply to the plant.
[0004]
[Patent Document 1]
JP-A-8-177433 [0005]
[Problems to be solved by the invention]
In the above-mentioned Patent Document 1, when the oil temperature of the hydraulic oil is extremely low, such as during a warm-up operation immediately after the start of the engine, since the viscosity is high and the passage pressure loss is large, the hydraulic pressure is supplied to the variable valve mechanism. Is banned. Separately, if the oil temperature of the hydraulic oil becomes extremely high during the operation of the engine after the completion of warm-up, the hydraulic pressure of the hydraulic oil supplied from the oil pump will decrease, ensuring the operation responsiveness of the variable valve mechanism. It is difficult to secure a hydraulic pressure that can be used. If the capacity of the oil pump, which is a hydraulic power source, is increased to guarantee the above-described operation responsiveness, an increase in cost, an increase in friction, and the like will be caused.
[0006]
The present invention has been made in view of such a problem, and without increasing the cost and increasing the friction due to an increase in the capacity of a hydraulic source such as an oil pump, the hydraulic oil temperature rise and hydraulic pressure decrease of the hydraulic oil are not caused. It is a main object of the present invention to provide a novel variable valve operating device for an internal combustion engine that can reliably avoid a decrease in the operation responsiveness of the variable valve operating mechanism accompanying the above.
[0007]
[Means for Solving the Problems]
A first variable valve mechanism and a second variable valve mechanism that are operated by hydraulic pressure of hydraulic oil and change valve lift characteristics of an intake valve or an exhaust valve; a hydraulic source for pressurizing the hydraulic oil; A first hydraulic control valve for controlling a hydraulic pressure supplied to the valve mechanism, a second hydraulic control valve for controlling a hydraulic pressure supplied to the second variable valve mechanism, and a hydraulic pressure of hydraulic oil supplied from the hydraulic pressure source Or a detecting means for detecting the oil temperature. When a prohibition condition including that the hydraulic pressure detected by the detecting means is lower than the set hydraulic pressure or the detected oil temperature is higher than the set oil temperature is satisfied, the control proceeds to at least one of the first variable valve mechanism and the second variable valve mechanism. Prohibit hydraulic pressure supply.
[0008]
【The invention's effect】
According to the present invention, when the oil temperature of the hydraulic oil increases and the hydraulic pressure decreases, the supply of the hydraulic pressure to at least one of the first variable valve mechanism and the second variable valve mechanism is prohibited. It is possible to reliably avoid a decrease in the operational response of the variable valve mechanism due to an increase in oil temperature and a decrease in oil pressure.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0010]
FIG. 1 is a configuration diagram schematically showing a variable valve operating device for an internal combustion engine according to the present invention.
[0011]
This variable valve device is operated by hydraulic pressure of hydraulic oil (lubricating oil) to change two valve operating mechanisms capable of changing a valve lift characteristic of the intake valve 15, that is, a variable valve lift amount of the intake valve 15. A variable valve lift changing mechanism (first variable valve mechanism) 13 and a valve timing changing mechanism (second variable valve mechanism) 17 capable of changing the valve timing of the intake valve 15 are provided. Hereinafter, the valve lift changing mechanism is referred to as VVL (Variable Valve Lifter), and the valve timing changing mechanism is referred to as VTC (Valve Timing Controller).
[0012]
These VVL13 and VTC17 are known as disclosed in the above-mentioned JP-A-8-177433 and JP-A-8-177426, and will be described only briefly here. The VVL 13 switches a valve lift amount and an operating angle in two stages by selectively using a high-speed cam 14a and a low-speed cam 14b provided on a cam shaft 14, and a valve lifter 16 of an intake valve 15 is provided with a valve lifter 16 according to oil pressure. A switching mechanism for switching between the high speed cam 14a and the low speed cam 14b for use is provided. The VTC 17 has an inner housing that rotates with the camshaft 14 of the intake valve 15 and an outer housing that rotates with a cam pulley to which rotational power is transmitted from a crankshaft via a timing belt. , The phase of the camshaft 14 relative to the crank angle of the crankshaft, that is, the phase of the operating center angle of the intake valve 15 is changed, thereby continuously changing the valve timing (opening / closing timing) of the intake valve 15. I do.
[0013]
The hydraulic pressure supplied to the VVL 13 is switched and controlled by a VVL solenoid 11 as a first hydraulic control valve, and the hydraulic pressure supplied to the VTC 17 is switched and controlled by a VTC solenoid 18 as a second hydraulic control valve. The operation of these solenoids 11, 18 is controlled by the control unit 1. The control unit 1 is a digital computer having a CPU, a memory, and an input / output interface, and includes a water temperature signal 2, an intake air amount signal 3, a throttle sensor signal 4, an oxygen sensor output signal 5, a crankshaft rotation signal 6, In addition to the signal 20 from the cam angle sensor 19 for detecting the angle of the camshaft 14, a signal 37 from an oil temperature sensor 36 described later, a signal from the VVL oil pressure sensor 21, and the like are input. Based on the signals indicating these engine operating conditions, the control unit 1 outputs the air-fuel ratio control signal 7 and the ignition timing control signal 8 to the corresponding actuator, and outputs the VTC control signal 9 to the VTC solenoid 18, and , A VVL solenoid signal 10 to a VVL solenoid 11 to control its operation.
[0014]
FIG. 2 shows a hydraulic circuit of VVL13 and VTC17. As is well known, an oil pump 31 serving as a hydraulic oil pressure source is driven by a crankshaft to pressurize the hydraulic oil and feed it to a main gallery 32 in a cylinder block 41. The oil pump 31 and the VVL solenoid 11 are connected by a VVL solenoid oil supply passage 34, and the VVL solenoid 11 and VVL 13 are connected by the VVL oil supply passage 12. That is, the VVL solenoid 11 is provided in the middle of the oil supply paths 34 and 12 connecting the oil pump 31 and the VVL 13. The oil pump 31 and the VTC solenoid 18 are connected by a VTC solenoid oil supply passage 33, and the VTC solenoid 18 and the VTC 17 are connected by a VTC oil supply passage 19. That is, the VTC solenoid 18 is provided in the middle of the oil supply passages 33 and 19 connecting the oil pump 31 and the VTC 17.
[0015]
The oil temperature sensor 36 is provided at a junction on the upstream side (oil pump 31 side) of the VTC solenoid oil supply passage 33 and the VVL solenoid oil supply passage 34, and detects the oil temperature of the working oil supplied from the oil pump 31.
[0016]
The VVL oil pressure sensor 21 is provided in the middle of the VVL oil supply passage 12 and basically detects the oil pressure supplied to the VVL 13. Based on the hydraulic pressure supplied to the VVL 13, the switching determination of the VVL 13 and the like are performed. This technique is described in detail in Japanese Patent Application No. 2002-272992 filed earlier by the present applicant.
[0017]
The VVL oil pressure sensor 21 also has a function of detecting the oil pressure of the hydraulic oil supplied from the oil pump 31 in order to determine the prohibition of the operation of the VVL 13 / VTC 17 in the second and fourth embodiments described later. . As described above, the bypass passage 35 that connects the oil pump 31 and the VVL solenoid 11 by bypassing the VVL solenoid 11 is provided so that the VVL oil pressure sensor 21 can detect the supply oil pressure from the oil pump 31.
[0018]
The bypass passage 35 also has the effect of accelerating the rise of the hydraulic pressure of the VVL 13. However, the bypass passage 35 is provided with an orifice or the like so that the VVL 13 does not malfunction due to the hydraulic pressure supplied to the VVL 13 via the bypass passage 35 when the VVL solenoid 11 is turned off.
[0019]
FIG. 3 shows an operation region of the VVL 13 according to the engine load and the engine speed. In the initial state where the oil pressure is not supplied to the VVL 13 / OFF state (non-operating state), the low-speed cam 14b on the low lift / small operating angle side is used, and when the oil pressure is supplied to the VVL 13 (ON state / operating state). Is switched to the high-speed cam 14a on the high lift / large operation angle side.
[0020]
FIG. 4 shows an operation range of the VTC 17 according to the engine load and the engine speed. In the initial state where the oil pressure is not supplied to the VTC 17 / OFF state (non-operating state), the opening / closing timing of the intake valve 15 is the most retarded, and when the oil pressure is supplied to the VTC 17 (ON state / operating state), The opening / closing timing of the intake valve 15 is continuously changed and controlled to the advanced side.
[0021]
FIG. 5 is a diagram in which the VVL operation region and the VTC operation region are overlapped. As shown in the figure, the operation region of the VVL 13 and the operation region of the VTC 17 overlap over a relatively wide engine load / rotation region (broken line region in the figure) R1.
[0022]
6 to 10 are flowcharts showing the flow of control stored and executed by the control unit 1. These routines are repeatedly executed every predetermined period (for example, every 10 ms).
[0023]
Referring to FIG. 6, in S (step) 1, VVL switching permission flag Vv and VTC conversion permission flag Vt are initialized, that is, set to 0. When the VVL switching permission flag Vv is 0, the supply of the hydraulic pressure from the VVL solenoid 11 to the VVL 13 is prohibited. That is, the operation (switching) of the VVL 13 is prohibited, and the low-speed cam 14b is used. When the VVL switching permission flag Vv is 1, the supply of hydraulic pressure from the VVL solenoid 11 to the VVL 13 is permitted. When the VTC conversion permission flag Vt is 0, the supply of hydraulic pressure from the VTC solenoid 18 to the VTC 17 is prohibited. That is, the operation (conversion) of the VTC 17 is prohibited, and the valve timing of the intake valve 15 is the most retarded. When the VTC conversion permission flag Vt is 1, the supply of hydraulic pressure to the VTC 17 is permitted.
[0024]
In S2, referring to a map as shown in FIG. 3, it is determined whether or not the engine load and the engine speed (engine operation region) are in the VVL13 ON region. If it is in the ON area of the VVL 13, the VVL switching permission flag Vv is set (set to 1) in S3. In S4, referring to a map as shown in FIG. 4, it is determined whether or not the engine load and the engine speed are in the VTC 17 ON region. If it is in the ON area of the VTC 17, the VTC conversion permission flag Vt is set (set to 1) in S5.
[0025]
FIG. 7 is a flowchart showing a control flow according to the first embodiment of the present invention. In S11, the values of the VVL switching permission flag Vv and the VTC conversion permission flag Vt set by the above-described routine of FIG. 6 and the like are read. In S12, it is determined whether the VVL switching permission flag Vv is 1, that is, whether the engine load and the engine speed are in the ON region of the VVL13. In S13, it is determined whether the VTC conversion permission flag Vt is 1, that is, whether the engine load and the engine speed are in the VTC 17 ON region. In S14, the oil temperature Ot of the working oil is detected by the oil temperature sensor 36, and in S15, it is determined whether or not the detected oil temperature Ot is higher than the first reference oil temperature Ot2.
[0026]
When all the prohibition conditions of S12, S13, and S15 described above are satisfied, that is, the engine operating range (the hatched region R1 in FIG. 5) of the engine load and the engine speed at which both the VVL 13 and the VTC 17 are to be operated, and When the detected oil temperature Ot is higher than the first reference oil temperature Ot2, the process proceeds to S16, and the VVL switching permission flag Vv is set to 0. As a result, the supply of the hydraulic pressure to the VVL 13 is prohibited, and the operation of the VVL 13 is prohibited (prohibiting means).
[0027]
In S17, it is determined whether or not the detected oil temperature Ot of the oil temperature sensor 36 is higher than the second reference oil temperature Ot3. The second reference oil temperature Ot3 is set to a value higher than the first reference oil temperature Ot2. If the prohibition conditions of S12, S13, and S15 described above are satisfied and the detected oil temperature Ot is higher than the second reference oil temperature Ot3 in S17, the process proceeds to S18, and the VTC conversion permission flag Vt is set to 0. As a result, the supply of the hydraulic pressure to the VTC 17 is prohibited, and the operation of the VTC 17 is prohibited (second prohibiting means).
[0028]
According to the first embodiment, the following effects (1) to (3) can be obtained.
[0029]
(1) In a situation in which the operation responsiveness of the VVL 13 and the VTC 17 cannot be guaranteed due to a decrease in the oil pressure due to an increase in the oil temperature, it is possible to reliably prevent both the VVL 13 and the VTC 17 from operating, and thus fail-safe. Excellent in nature. In addition, it is not necessary to increase the capacity of the oil pump 31 in order to secure the operation responsiveness, so that cost and friction can be reduced.
[0030]
(2) With an increase in the oil temperature and a decrease in the oil pressure, first, only the operation of the VVL 13 that changes the valve lift characteristics in a stepwise manner is prohibited, and the operation of the VTC 17 that continuously changes the valve lift characteristics is prioritized. , The conversion range of the VTC 17 can be expanded to the limit, and a decrease in the driving performance such as fuel efficiency is reduced and suppressed as compared with the case where the operation of the VTC 17 is prohibited first or the case where both the operations of the VVL 13 and the VTC 17 are simultaneously prohibited. be able to. More specifically, if VTC 17 is prohibited first, operation is possible only in regions R3 and R4 (FIG. 4). If both VTC 17 and VVL 13 are prohibited, operation is possible only in R5 (FIG. 5). As described above, the variable valve mechanism cannot be used in a region where the fuel efficiency can be improved. On the other hand, in the present embodiment, since the operation of the VTC is prioritized by turning off the VVL first, the operation can be performed in the regions R2 and R5 (FIG. 5) corresponding to the fuel consumption region, and the fuel consumption can be improved. .
[0031]
(3) As a substitute for the oil pressure supplied from the oil pump 31, the oil temperature detected by the oil temperature sensor 36 which is also used in a general engine is used to determine whether or not to operate the VVL13 / VTC17 (S15, S17). Therefore, the oil pressure sensor for directly detecting the oil pressure supplied from the oil pump 31 can be omitted, and the configuration can be simplified.
[0032]
FIG. 8 is a flowchart showing a control flow according to the second embodiment of the present invention. The second embodiment differs from the first embodiment in that the operation prohibition determination (S15a, S17a) of the VVL13 / VTC17 is performed using the oil pressure detected by the VVL oil pressure sensor 21.
[0033]
The processing of S11 to S13 is the same as in the first embodiment. In S14a, the output value (detected oil pressure) Op of the VVL oil pressure sensor 21 is read. In S15a, it is determined whether the detected oil pressure Op of the VVL oil pressure sensor 21 is lower than the first set oil pressure Op2.
[0034]
When all the prohibition conditions of S12, S13, and S15a are satisfied, that is, it is determined that the engine load and the engine speed range in which both VVL13 and VTC17 are to be operated, and that the detected hydraulic pressure Op is lower than the first set hydraulic pressure Op2. Then, the process proceeds to S16, where the VVL switching permission flag Vv is set to 0. Accordingly, the supply of the hydraulic pressure to the VVL 13 is prohibited, and the operation of the VVL 13 is prohibited.
[0035]
In S17a, it is determined whether or not the detected oil pressure Op of the VVL oil pressure sensor 21 is lower than the second set oil pressure Op3. The second set oil pressure Op3 is set to a value lower than the first set oil pressure Op2. When the above prohibition condition is satisfied and the detected oil pressure Op of the oil pressure sensor 36 is lower than the second set oil pressure Op3, the process proceeds to S18, and the VTC conversion permission flag Vt is set to 0. As a result, the supply of the hydraulic pressure to the VTC 17 is prohibited, and the operation of the VTC 17 is prohibited.
[0036]
According to the second embodiment, the following effects (4) and (5) are obtained in addition to the effects (1) and (2) of the first embodiment.
[0037]
(4) Since the operation prohibition determination (S15a, S17a) of VVL13 and VTC17 is performed using the oil pressure directly detected by the VVL oil pressure sensor 21 instead of the oil temperature which is a substitute characteristic, the control accuracy is excellent. ing.
[0038]
(5) In order to perform the switching determination control of the VVL 13, etc., the operation inhibition determination of the VVL 13 and the VTC 17 is performed using the existing VVL oil pressure sensor 21 capable of detecting the hydraulic pressure supplied from the VVL solenoid 11 to the VVL 13 (S15a, S17a). Therefore, it is not necessary to separately provide a hydraulic pressure sensor for performing the operation prohibition determination, and the configuration can be simplified.
[0039]
FIG. 9 is a flowchart showing the flow of control according to the third embodiment of the present invention. The processing of S11 to S13 is the same as in the first embodiment. In S14b, the detected oil temperature Ot of the oil temperature sensor 36 is read. In S15b, it is determined whether or not the detected oil temperature Ot of the oil temperature sensor 36 is higher than the reference oil temperature Ot1. This reference oil temperature Ot1 is, for example, substantially the same value as the first reference oil temperature Ot2 of the first embodiment.
[0040]
When all the prohibition conditions of S12, S13, and S15b are satisfied, that is, when the engine load and the engine rotation range are to operate both VVL13 and VTC17, and the detected oil temperature Ot is higher than the reference oil temperature Ot1 Proceeds to S16b, sets the VVL switching permission flag Vv to 0, and sets the VTC conversion permission flag Vt to 0. Accordingly, the supply of the hydraulic pressure to the VVL 13 is prohibited, and the operation of the VVL 13 is prohibited. At the same time, the supply of the hydraulic pressure to the VTC 17 is prohibited, and the operation of the VTC 17 is prohibited.
[0041]
In the third embodiment, in addition to the effects (1) and (3) of the first embodiment described above, when the detected oil temperature Ot exceeds the reference oil temperature Ot1, both the operations of the VVL 13 and the VTC 17 are performed. Since the control is prohibited all at once, the control can be simplified.
[0042]
FIG. 10 is a flowchart showing a control flow according to the fourth embodiment of the present invention. The processing of S11 to S13 is the same as in the first embodiment. In S14c, the output value (detected pressure) Op of the VVL oil pressure sensor 21 is read. In S15c, it is determined whether or not the detected oil pressure Op of the VVL oil pressure sensor 21 is lower than the set oil pressure Op1. This reference oil pressure Op1 is, for example, substantially the same value as the first reference oil pressure Op2 of the second embodiment.
[0043]
When all the prohibition conditions of S12, S13, and S15c are satisfied, that is, it is determined that the engine load and the engine speed range in which both the VVL 13 and the VTC 17 are to be operated, and that the detected hydraulic pressure Op is lower than the set hydraulic pressure Op1. Then, the process proceeds to S16c, where the VVL switching permission flag Vv is set to 0, and the VTC conversion permission flag Vt is set to 0. As a result, the supply of the hydraulic pressure to the VVL 13 is prohibited, the operation of the VVL 13 is prohibited, and the supply of the hydraulic pressure to the VTC 17 is prohibited, so that the operation of the VTC 17 is prohibited.
[0044]
In the fourth embodiment, in addition to the effects (1), (4), and (5) of the first and second embodiments described above, when the detected oil pressure Op becomes lower than the set oil pressure Op1, the VVL13 and VTC17 Since both operations are prohibited at the same time, control can be simplified.
[0045]
Although the present invention has been described based on the specific embodiments as described above, the present invention is not limited to these embodiments, and various modifications and changes may be made without departing from the spirit and scope of the present invention. Is included. For example, the present invention may be applied to a device in which a plurality of variable valve mechanisms are applied to an exhaust valve.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a variable valve operating device for an internal combustion engine according to the present invention.
FIG. 2 is a hydraulic circuit diagram of a valve lift changing mechanism and a valve timing changing mechanism of the variable valve operating device.
FIG. 3 is a characteristic diagram showing an operation region of a valve lift changing mechanism.
FIG. 4 is a characteristic diagram showing an operation region of a valve timing changing mechanism.
FIG. 5 is a characteristic diagram in which an operation area of a valve lift changing mechanism and an operation area of a valve timing changing mechanism are overlapped.
FIG. 6 is a flowchart showing a control process for prohibiting and permitting operation of a valve lift changing mechanism and a valve timing changing mechanism according to an engine load and an engine speed.
FIG. 7 is a flowchart showing a control flow according to the first embodiment of the present invention.
FIG. 8 is a flowchart showing a control flow according to a second embodiment of the present invention.
FIG. 9 is a flowchart showing a control flow according to a third embodiment of the present invention.
FIG. 10 is a flowchart showing a control flow according to a fourth embodiment of the present invention.
[Explanation of symbols]
11 VVL solenoid (first hydraulic control valve)
13. Valve lift change mechanism (first variable valve mechanism)
17: Valve timing change mechanism (second variable valve mechanism)
18 VTC solenoid (second hydraulic control valve)
21 ... oil pressure sensor 31 ... oil pump (oil pressure source)
35 ... bypass passage 36 ... oil temperature sensor

Claims (9)

A first variable valve mechanism and a second variable valve mechanism that are operated by hydraulic pressure of hydraulic oil and change valve lift characteristics of an intake valve or an exhaust valve;
A hydraulic pressure source for pressurizing the hydraulic oil,
A first hydraulic control valve for controlling a hydraulic pressure supplied to the first variable valve mechanism;
A second hydraulic control valve for controlling a hydraulic pressure supplied to the second variable valve mechanism,
Detecting means for detecting the oil pressure or oil temperature of the hydraulic oil supplied from the oil pressure source,
Determining means for determining a prohibition condition including that the hydraulic pressure detected by the detecting means is lower than the set hydraulic pressure or the detected oil temperature is higher than the set oil temperature;
Prohibiting means for prohibiting hydraulic pressure supply to at least one of the first variable valve mechanism and the second variable valve mechanism when the prohibition condition is satisfied;
A variable valve device for an internal combustion engine having the same. A first variable valve mechanism and a second variable valve mechanism that are operated by hydraulic pressure of hydraulic oil and change valve lift characteristics of an intake valve or an exhaust valve;
A hydraulic pressure source for pressurizing the hydraulic oil,
A first hydraulic control valve for controlling a hydraulic pressure supplied to the first variable valve mechanism;
A second hydraulic control valve for controlling a hydraulic pressure supplied to the second variable valve mechanism,
Detecting means for detecting the oil pressure or oil temperature of the hydraulic oil supplied from the oil pressure source,
Determining means for determining a prohibition condition including that the hydraulic pressure detected by the detecting means is lower than the set hydraulic pressure or the detected oil temperature is higher than the set oil temperature;
Prohibiting means for prohibiting hydraulic pressure supply to the first variable valve mechanism when the prohibition condition is satisfied;
A variable valve device for an internal combustion engine having the same. The first variable valve mechanism is a valve lift changing mechanism capable of changing a valve lift amount of an intake valve or an exhaust valve,
3. The variable valve operating device for an internal combustion engine according to claim 2, wherein the second variable valve operating mechanism is a valve timing changing mechanism capable of changing a valve timing of an intake valve or an exhaust valve. The first variable valve mechanism changes the valve lift characteristics in a stepwise manner.
4. The variable valve apparatus for an internal combustion engine according to claim 2, wherein the second variable valve mechanism changes the valve lift characteristic continuously. When the prohibition condition is satisfied and the detected oil pressure is lower than a second set oil pressure lower than the set oil pressure or the detected oil temperature is higher than a second set oil temperature higher than the set oil temperature 5. The variable valve operating device for an internal combustion engine according to claim 2, further comprising a second prohibiting unit that prohibits the supply of the hydraulic pressure to the second variable valve operating mechanism. 6. The prohibition condition according to claim 1, wherein the engine operation region is an operation region of the first variable valve mechanism, and the engine operation region is an operation region of the second variable valve mechanism. A variable valve operating device for an internal combustion engine according to any one of the above. 7. The variable valve apparatus for an internal combustion engine according to claim 1, wherein said detection means is an oil temperature sensor for detecting an oil temperature of hydraulic oil supplied from a hydraulic pressure source. 7. The variable valve apparatus for an internal combustion engine according to claim 1, wherein said detection means is a hydraulic pressure sensor that detects a hydraulic pressure of hydraulic oil supplied from a hydraulic pressure source. The oil pressure sensor is provided in an oil passage connecting the first oil pressure control valve and the first variable valve mechanism, and has a function of detecting oil pressure supplied to the first variable valve mechanism,
9. The variable valve train for an internal combustion engine according to claim 8, wherein a bypass passage is provided for connecting a hydraulic pressure source and a hydraulic pressure sensor by bypassing the first hydraulic pressure control valve.

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