JP3123373B2 - Variable valve train for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus for variably controlling a valve lift characteristic of an intake valve or an exhaust valve of an internal combustion engine (both are generally referred to as intake and exhaust valves) in accordance with engine operating conditions. .

[0002]

2. Description of the Related Art In general, a valve train for an internal combustion engine transmits a cam lift to intake and exhaust valves via a rocker arm and a swing arm, and pushes open and exhaust valves urged in a closing direction by a valve spring. However, since, for example, preferable valve lift characteristics are different between a low-speed region and a high-speed region of the engine, various variable valve operating devices capable of switching the valve lift characteristics depending on operating conditions have been proposed. One example is disclosed in, for example, JP-A-63-167016.
In Japanese Unexamined Patent Application Publication No. H10-207, a low-speed cam and a high-speed cam having different profiles are arranged side by side on a camshaft, and a driven main rocker arm and a sub-rocker arm are switched to a connected state or a disconnected state as necessary. Configurations are known. In general, a high-speed cam is set to have both a larger cam lift and a longer valve opening period than a low-speed cam.

[0003] In addition, some variable valve actuating devices using a valve timing adjustment mechanism for delaying the valve timing of opening and closing the intake and exhaust valves by changing the phase of the camshaft with respect to the crankshaft have been conventionally used. Has been put to practical use. That is, in this case, the operating center angle (the crank angle that is the center between the opening timing and the closing timing) changes without changing the shape of the valve lift characteristic.

[0004] Further, there has also been proposed a variable valve actuation device in which a former valve lift adjusting mechanism by cam switching and a latter valve timing adjusting mechanism are combined. By combining the two, the valve lift can be changed in magnitude, and at the same time, the opening timing and the closing timing can be variably controlled, so that the requirements can be further adapted to the requirements under each operating condition.

[0005]

The variable valve mechanisms such as the valve lift adjustment mechanism and the valve timing adjustment mechanism described above are generally of a hydraulic drive type, and apply a lubricating oil pressure of the internal combustion engine to an actuator section. It is switched by supplying or stopping.

[0006] When the temperature of the lubricating oil exceeds 100 ° C, the viscosity of the lubricating oil decreases, and the lubrication of each sliding portion may be insufficient. Therefore, the oil temperature of the lubricating oil is detected directly or indirectly, and when this detected oil temperature rises above the set temperature, the supply of the hydraulic pressure to the variable valve mechanism is stopped, the output is reduced, and A proposal has been already made to prevent an increase in oil temperature and to actively promote a temperature decrease (Japanese Patent Application No. 5-159124).

However, in an internal combustion engine equipped with a plurality of variable valve mechanisms such as the above-described valve lift adjustment mechanism and valve timing adjustment mechanism, the supply of hydraulic pressure to each variable valve mechanism is suddenly increased as the oil temperature rises. If the vehicle is stopped, a very large change in torque is suddenly generated as a whole, and the driver may feel uncomfortable.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a plurality of variable valves which continuously or stepwise change the valve lift characteristics of an intake valve or an exhaust valve in response to supply and stop of hydraulic pressure to an actuator. Mechanism, a plurality of hydraulic control valves for respectively controlling hydraulic pressure supply to the actuator section of each variable valve mechanism, control means for outputting a control signal to each hydraulic control valve according to engine operating conditions, and lubrication of the internal combustion engine. An internal combustion system comprising: oil temperature detecting means for directly or indirectly detecting an oil temperature; and hydraulic pressure supply inhibiting means for inhibiting oil pressure supply by the hydraulic pressure control valve when the detected oil temperature exceeds a set temperature. In the variable valve operating device of the engine, among the plurality of variable valve operating mechanisms, the plurality of variable valve operating mechanisms that may be supplied with the hydraulic pressure under the same engine operating condition have the set temperatures different from each other. It is characterized in that was.

In particular, according to the second aspect of the present invention, the set temperature of the variable valve mechanism in which the valve lift characteristic changes continuously is set lower than the set temperature of the variable valve mechanism in which the valve lift characteristic changes stepwise. .

According to the third aspect of the present invention, the hydraulic stop operation of the variable valve mechanism in which the valve lift characteristic changes stepwise is performed after the detected oil temperature exceeds the set temperature and the operating condition is changed to the hydraulic stop condition. Until it becomes.

The variable valve mechanism in which the valve lift characteristic continuously changes is, for example, a valve timing adjustment mechanism that changes the phase of a camshaft with respect to a crankshaft. The variable valve mechanism that changes stepwise is, for example, a valve lift adjustment mechanism that transmits a lift of one of a low-speed cam and a high-speed cam to an intake / exhaust valve.

According to the fifth aspect of the present invention, a variable valve mechanism is provided for each of the intake valve and the exhaust valve, and the set temperature of the exhaust-side variable valve mechanism is adjusted by the setting of the intake-side variable valve mechanism. It was set lower than the temperature.

[0013]

According to the first aspect of the present invention, if the lubricating oil temperature rises excessively while the hydraulic pressure is being supplied to the actuator section of each variable valve mechanism, the supply of the hydraulic pressure to each variable valve mechanism is prohibited, Although the valve lift characteristic changes, the set temperatures at which the hydraulic pressure supply is prohibited are different from each other, so the hydraulic supply prohibition is sequentially executed by each variable valve mechanism. In other words,
The plurality of variable valve mechanisms do not switch at the same time based on the oil temperature, and the torque change is reduced.

In particular, according to the second aspect of the present invention, when the oil temperature rises,
First, the supply of hydraulic pressure to the variable valve mechanism in which the valve lift characteristic changes continuously is cut off, and then the supply of hydraulic pressure to the variable valve mechanism in which the valve lift characteristic changes stepwise is cut off.

According to the third aspect of the present invention, the latter operation of stopping the hydraulic pressure to the variable valve mechanism in which the valve lift characteristic changes stepwise is not forcibly performed during the supply of the hydraulic pressure, and the detected oil temperature falls below the set temperature. After that, when the operating condition becomes the condition for stopping the hydraulic pressure, the subsequent supply of the hydraulic pressure is prohibited. Therefore, there is no sudden fluctuation in torque.

According to a fourth aspect of the present invention, there is provided a valve timing adjusting mechanism.
By changing the phase of the camshaft with respect to the crankshaft, the valve lift characteristics are changed stepwise. The valve lift adjusting mechanism changes the valve lift characteristics in a stepwise manner by selectively transmitting either one of the low-speed cam and the high-speed cam to the intake / exhaust valve.

According to the invention of claim 5, when the oil temperature rises,
First, the supply of hydraulic pressure to the variable valve mechanism on the exhaust side, which has little effect on torque, is cut off, and then the supply of hydraulic pressure to the variable valve mechanism on the intake side is cut off.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an embodiment of a variable valve apparatus in which a valve lift adjusting mechanism 40 and a valve timing adjusting mechanism 70 are provided as variable valve operating mechanisms on the intake valve 9 side.

First, the valve lift adjusting mechanism 40 will be described. As shown in FIGS. 2 and 3, each cylinder is provided with one main rocker arm 1 corresponding to a pair of intake valves 9. The base end of the main rocker arm 1 is swingably supported by a cylinder head 69 via a main rocker shaft 3 common to each cylinder. An adjusting screw 10 that is in contact with the stem top of each intake valve 9 is fastened to the tip of the main rocker arm 1 via a nut 11.

The main rocker arm 1 has a shaft 13
The roller 14 is rotatably supported via a needle bearing, and the low-speed cam 21 is in contact with the roller 14.

The main rocker arm 1 is formed in a substantially rectangular shape in plan view, and the sub rocker arm 2 is provided in an opening formed alongside the roller 14. The base end of the sub rocker arm 2 is connected to the main rocker arm 1 via a sub rocker shaft 16 so as to be relatively rotatable. The sub rocker shaft 16 is slidably fitted in a hole 17 formed in the sub rocker arm 2, while being press-fitted into a hole 18 formed in the main rocker arm 1.

The sub rocker arm 2 does not have a portion that comes into contact with the intake valve 9 and, as shown in FIG. 3, a cam follower portion 23 that comes into sliding contact with the high-speed cam 22 is formed at the tip thereof so as to protrude in an arc shape. On the side, a lost motion spring 25 for pressing the cam follower portion 23 against the high-speed cam 22 is interposed.

A lost motion spring 25 is located on the main rocker arm 1 just below the sub rocker arm 2.
Are formed integrally with each other. The lower end of the coiled lost motion spring 25 has a concave portion 26.
Of the sub rocker arm 2 via a retainer 27 that slidably fits into the recess 26.

The low-speed cam 21 and the high-speed cam 22 are integrally formed on a common camshaft 72, and have different shapes (sizes) so as to satisfy the valve lift characteristics required when the engine is running at a low speed and at a high speed. Are also included. In this embodiment, as shown in FIG. 5, the high-speed cam 22 has a profile in which both the valve lift and the operating angle (valve opening period) are larger than the low-speed cam 21.

To properly connect the two rocker arms 1 and 2, plungers 33, 31, and 34 are slidably fitted over the main rocker arm 1 and the sub rocker arm 2. A hydraulic passage 43 is connected to the rear of the plunger 33 serving as an actuator section.
A return spring 38 is provided behind the back.

When the operating oil pressure guided from the hydraulic passage 43 is low, the plungers 33 and 31 are respectively accommodated in the sub rocker arm 2 and the main rocker arm 1 by the urging force of the return spring 38, and do not restrict the swing of both. That is, both are in the detached state. On the other hand, when the operating oil pressure guided from the hydraulic passage 43 rises, the plungers 33 and 31 slide while compressing the return spring 38, and are fitted over the main rocker arm 1 and the sub rocker arm 2 so that they are integrally formed. Rocks.

The hydraulic passage 43 is provided through the inside of the main rocker arm 1 and the main rocker shaft 3, and the discharge hydraulic pressure of the oil pump 57 is guided via the electromagnetic switching valve 45 only at a predetermined high rotation. .

Next, the valve timing adjusting mechanism 70 will be described. The valve timing adjusting mechanism 70 is provided between the camshaft 72 and the cam pulley 71, and changes the phases of the two according to the operating conditions to change the opening / closing timing of the intake valve 9. The cam pulley 71 is transmitted with a torque from a crankshaft (not shown) via a timing belt 66.

As shown in FIG. 4, a cylindrical inner housing 65 is fixed to an end of the camshaft 72 via a bolt 64. A cylindrical outer housing 63 rotatably fitted to the outer periphery of the inner housing 65 is provided, and a cam pulley 71 is formed integrally with the outer housing 63.

A ring-shaped helical gear 73 is interposed between the inner housing 65 and the outer housing 63. The helical gear 73 has helical splines formed on the inner and outer circumferences. Each helical spline meshes with the outer circumference of the inner housing 65 and the inner circumference of the outer housing 63, and when the helical gear 73 moves in the axial direction, the outer housing 63 Inner housing 6
5, the phase of the cam shaft 72 with respect to the cam pulley 71 changes.

A hydraulic chamber 75 is defined between the inner housing 65, the outer housing 63, and the helical gear 73, which are actuator portions. When the hydraulic pressure guided to the hydraulic chamber 75 rises above a predetermined value, the helical gear 73
Moves from the initial position in the axial direction against the return spring 74, so that the camshaft 72 rotates in a direction to advance the opening / closing timing of the intake valve 9.

That is, when the helical gear 73 is at the initial position, the opening and closing timing of the intake valve 9 is relatively late as shown in the upper and lower parts of FIG.
Is maximized, the opening / closing timing of the intake valve 9 is relatively advanced, as shown in the middle part of FIG.

In the hydraulic chamber 75, a shaft hole 78 formed in the camshaft 72, an oil gallery 59 formed in the cylinder head 69, an orifice 77, and a main gallery 58 formed in the cylinder block 68 are provided. Through this, the discharge oil pressure from the oil pump 57 is introduced.

In order to appropriately release the hydraulic pressure, an electromagnetic switching valve 79 is provided at the other end of the camshaft 72, and is controlled to open and close according to engine operating conditions.
The electromagnetic switching valve 79 opens the shaft hole 78 as shown in the drawing when the electric power is not supplied to reduce the hydraulic pressure guided to the hydraulic chamber 75, and closes the shaft hole 78 when the electric power is supplied to increase the hydraulic pressure guided to the hydraulic chamber 75. ing.

As a control means of the valve lift adjusting mechanism 40 and the valve timing adjusting mechanism 70, a control unit 51 for controlling energization of the electromagnetic switching valve 45 and the electromagnetic switching valve 79 is provided.

The control unit 51 receives an engine rotation signal, an engine load signal, a cooling water temperature signal, a supercharging pressure signal of the intake air from the supercharger, and the like. , While smoothly switching the valve lift characteristics.

Further, at an appropriate position in the lubrication system of the internal combustion engine,
An oil temperature sensor 80 for detecting the lubricating oil temperature is provided,
The detection signal is input to the control unit 51. Instead of directly detecting the lubricating oil temperature in this way, the oil temperature may be indirectly estimated from the engine cooling water temperature or the like.

Next, the operation of the above embodiment will be described.

FIG. 5 is an explanatory diagram showing the control state of the valve lift adjusting mechanism 40 and the valve timing adjusting mechanism 70 with respect to the engine operating conditions. As shown in FIG. The cam 22 is selected, and the valve timing adjusting mechanism 70 controls the opening / closing timing to be delayed. This increases the valve overlap. The electromagnetic switching valve 45 of the valve lift adjustment mechanism 40
ON corresponds to the high-speed cam 22 and OFF corresponds to the low-speed cam 21. The valve timing adjusting mechanism 70
ON of the electromagnetic switching valve 79 of the
Correspond to the lag side, respectively. That is, in the engine high speed range, the electromagnetic switching valve 45 is turned on and the electromagnetic switching valve 79 is turned off.

In the low-speed region of the engine and on the high-load side, the electromagnetic switching valve 45 is turned off and the electromagnetic switching valve 79 is turned on, so that the low-speed cam 21 is opened and closed.

Further, in the low-speed region of the engine and on the low-load side, the two solenoid-operated directional control valves 45 and 79 are turned off, and the low-speed cam 21 and the opening / closing timing are delayed.

When the electromagnetic switching valves 45 and 79 are turned on,
The OFF control is performed based on the engine operating conditions, that is, the engine load and the rotation speed, with reference to a control map given to the control unit 51 in advance. Since the electromagnetic switching valve 45 and the electromagnetic switching valve 79 are controlled based on respective control maps, the rough classification in FIG. 5 shows that both are not turned on at the same time. However, actually, the ON regions partially overlap, and both can be turned ON at the same time.

On the other hand, the control unit 51 constantly monitors, based on the oil temperature detected by the oil temperature sensor 80, whether the lubricating oil temperature is abnormally increased. If the oil temperature is equal to or higher than the set temperature, the electromagnetic switching valve 4
5, 79 ON operation is prohibited.

The flowcharts shown in FIG. 6 and FIG.
This shows a specific control flow. In step 1 of the main flowchart of FIG. 6, the engine operating conditions represented by the engine load and rotation speed are read, and in step 2, the valve timing adjusting mechanism 70, ie, the electromagnetic switching valve It is determined whether or not it is the ON area of No. 79. Here, if it is outside the ON region, the process proceeds to step 3 and the electromagnetic switching valve 79 is turned off. On the other hand, if it is in the ON region, the process proceeds to step 4, and the state of the first permission flag FT based on the oil temperature is determined. As for the permission flag FT, “1” indicates a state in which the ON of the electromagnetic switching valve 79 is permitted, and “0” indicates a state in which the ON is prohibited.
Therefore, only when the permission flag FT is "1" in step 4, the process proceeds to step 5, and the electromagnetic switching valve 79 is turned on. If the permission flag FT is "0", the process proceeds to step 3, where the electromagnetic switching valve 79 is turned off. Similarly, in step 6, the engine operating condition is changed to the valve lift adjusting mechanism 40.
That is, it is determined whether or not it is in the ON region of the electromagnetic switching valve 45,
If it is in the ON region, the electromagnetic switching valve 45 is turned ON on condition that the second permission flag FL is "1" indicating the ON permission state (steps 8 and 9). Otherwise, in step 7, the electromagnetic switching valve 45 is turned off.

The permission flags FT and FL are set according to the flowchart of FIG. That is, the oil temperature T detected by the oil temperature sensor 80 in step 11 is read and is
The set temperature T1 and the second set temperature T2 are compared with each other in Steps 12 and 15, respectively. If the actual oil temperature T is lower than the first set temperature T1, the first permission flag FT
Is set to "1" (step 13), and when the temperature is equal to or higher than the first set temperature T1, the first permission flag FT is set to "0" (step 14). Similarly, the actual oil temperature T becomes equal to the second set temperature T2.
If the temperature is less than the second set temperature T2, the second permission flag FL is set to "1" (step 16).
The permission flag FL is set to "0" (step 17). Here, the valve timing adjustment mechanism 70, that is, the electromagnetic switching valve 7
The first set temperature T1 which is the ON prohibition temperature of No. 9 is set lower than the second set temperature T2 which is the ON prohibition temperature of the valve lift adjusting mechanism 40, that is, the electromagnetic switching valve 45.

Accordingly, in this embodiment, when the lubricating oil temperature rises abnormally, first, the electromagnetic switching valve 79
The state returns to the FF state, and then the electromagnetic switching valve 45 returns to the OFF state. Therefore, the output of the internal combustion engine is suppressed, and a further increase in the temperature of the lubricating oil is prevented. Further, a decrease in lubricating oil temperature is promoted. At this time, the two variable valve operating mechanisms, that is, the valve timing adjusting mechanism 70 and the valve lift adjusting mechanism 40 are not switched at the same time, but a slight time difference is given, so that the torque fluctuation is reduced. In particular,
Since the valve timing adjusting mechanism 70 in which the valve lift characteristic continuously changes is turned off first, the sudden torque change can be further alleviated.

FIG. 8 shows another embodiment in which the setting of the permission flags FT and FL is different. In this embodiment, step 21
In step 22, the oil temperature T detected by the oil temperature sensor 80 is read, and is compared with the first set temperature T1 in step 22. Also in this embodiment, the first set temperature T1 at which the electromagnetic switching valve 79 is turned on is set to be lower than the second set temperature T2 at which the electromagnetic switching valve 45 is turned on. If the actual oil temperature T is lower than the first set temperature T1, the process proceeds to step 23, where the first permission flag FT and the second permission flag FL are set to "1". If the temperature is equal to or higher than the first set temperature T1, the first permission flag FT is set to "0" in step S24. Then, in step 25, it is determined whether or not the engine operating condition is in the OFF region of the valve lift adjusting mechanism 40, that is, the electromagnetic switching valve 45.
In step 6, the second permission flag FL is set to "0". If it is outside the OFF region, that is, if it is the ON region, the oil temperature T
Is compared with the second set temperature T2, and if the temperature is equal to or higher than the second set temperature T2, the second permission flag FL is set to "0" in step 26.
And

Therefore, in this embodiment, when the lubricating oil temperature rises abnormally, the valve timing adjusting mechanism 70
Immediately returns to the OFF state, and the output of the internal combustion engine is suppressed. And the valve lift adjusting mechanism 4
The 0 electromagnetic switching valve 45 returns to the OFF state only when the operating condition is out of the ON region. Therefore, there is no possibility that the torque of the internal combustion engine suddenly drops suddenly during high-speed running and gives an uncomfortable feeling.

The embodiment in which the present invention is applied to an internal combustion engine provided with two variable valve mechanisms on the intake side has been described above. However, the present invention relates to an internal combustion engine provided with a larger number of variable valve mechanisms. Applicable to institutions. In the case where three or more variable valve mechanisms are provided, the set temperature may be made different only for those which are likely to be simultaneously turned ON under the same operating conditions.

The present invention can also be applied to a case where variable valve mechanisms are provided on each of the intake side and the exhaust side. FIG.
The flowchart of FIG. 7 shows an example of control in the case where variable valve mechanisms are provided on both the intake side and the exhaust side. That is, the oil temperature T detected by the oil temperature sensor 80 in step 31 is read, and is compared with the exhaust-side set temperature Te and the intake-side set temperature Ti in steps 32 and 35, respectively. If the actual oil temperature T is lower than the exhaust side set temperature Te, the exhaust side permission flag Fe is set to "1" (step 33). If the actual oil temperature T is higher than the exhaust side set temperature Te, the exhaust side permission flag Fe is set to "1". 0 "(step 34). Similarly, when the actual oil temperature T is lower than the intake side set temperature Ti, the intake side permission flag Fi is set to "1" (step 3).
6) If the temperature is equal to or higher than the intake side set temperature Ti, the intake side permission flag Fi is set to "0" (step 37). here,
The exhaust-side set temperature Te that is the ON prohibition temperature of the variable valve mechanism on the exhaust valve side is set lower than the intake-side set temperature Ti that is the ON prohibition temperature of the variable valve mechanism on the intake valve side.

Therefore, in this embodiment, when the lubricating oil temperature rises abnormally, the exhaust-side variable valve mechanism first returns to the OFF state, and then the intake-side variable valve mechanism turns off.
Return to the state. Therefore, the output of the internal combustion engine is suppressed, and a further increase in the temperature of the lubricating oil is prevented. Further, a decrease in lubricating oil temperature is promoted. At this time, since the variable valve mechanism on the exhaust side and the variable valve mechanism on the intake side are not switched at the same time, a slight time difference is given, so that torque fluctuation is reduced. In particular, since the exhaust valve side that has less influence on the torque is first switched to the OFF state, the driver feels less uncomfortable.

[0053]

As is apparent from the above description, according to the present invention, when the lubricating oil temperature rises excessively, the variable valve mechanism is switched to suppress the oil temperature rise, thereby avoiding poor lubrication. . At this time, the plurality of variable valve mechanisms are not switched at the same time based on the oil temperature but are switched sequentially, so that the torque change can be reduced.

In particular, according to the second aspect of the invention, the variable valve mechanism in which the valve lift characteristic changes continuously is preferentially switched, and the variable valve mechanism in which the valve lift characteristic changes stepwise is changed later. Since the switching is performed, the torque change can be made more gentle.

According to the third aspect of the present invention, there is no sudden change in torque during steady operation.

In particular, in the apparatus having a mechanism for changing the valve lift characteristic by switching between the low-speed cam and the high-speed cam as in the fourth aspect, the switching of the mechanism by the oil temperature is delayed so that the sudden torque is increased. Fluctuations can be avoided.

According to the fifth aspect of the present invention, since the exhaust valve side having less influence on the torque is switched first, the torque fluctuation can be suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing one embodiment of a variable valve apparatus according to the present invention.

FIG. 2 is an enlarged plan view of the rocker arm.

FIG. 3 is a sectional view of a rocker arm portion.

FIG. 4 is a sectional view of a valve timing adjustment mechanism.

FIG. 5 is a valve lift characteristic diagram of this embodiment.

FIG. 6 is a flowchart showing a flow of control of each variable valve mechanism according to engine operating conditions.

FIG. 7 is a flowchart showing a process for setting a permission flag based on oil temperature.

FIG. 8 is a flowchart showing another embodiment.

FIG. 9 is a flowchart showing an embodiment in which variable valve mechanisms are provided on both the intake valve side and the exhaust valve side.

[Explanation of symbols]

 Reference numeral 40: valve lift adjusting mechanism 45: electromagnetic switching valve 51: control unit 70: valve timing adjusting mechanism 79: electromagnetic switching valve 80: oil temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shin Nakamura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-63-167016 (JP, A) JP-A-5-205 5430 (JP, A) Japanese Utility Model Showa 62-61907 (JP, U) Japanese Utility Model Showa 62-45316 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01L 13/00 301 F01L 1/34

Claims (5)

(57) [Claims] 1. A plurality of variable valve mechanisms for continuously or stepwise changing a valve lift characteristic of an intake valve or an exhaust valve according to supply and stop of hydraulic pressure to an actuator section, and an actuator of each variable valve mechanism. A plurality of hydraulic control valves for respectively controlling the supply of hydraulic pressure to the unit, and control means for outputting a control signal to each hydraulic control valve according to the engine operating conditions,
Oil temperature detecting means for directly or indirectly detecting the lubricating oil temperature of the internal combustion engine, and oil pressure supply inhibiting means for inhibiting oil pressure supply by the oil pressure control valve when the detected oil temperature exceeds a set temperature. In the variable valve operating device for an internal combustion engine provided, among the plurality of variable valve operating mechanisms, for the plurality of variable valve operating mechanisms that may be supplied with hydraulic pressure under the same engine operating condition, the above set temperatures are respectively set. A variable valve train for an internal combustion engine, characterized in that it is different. 2. The method according to claim 1, wherein the set temperature of the variable valve mechanism in which the valve lift characteristic changes continuously is set lower than the set temperature of the variable valve mechanism in which the valve lift characteristic changes stepwise. Item 4. The variable valve train for an internal combustion engine according to Item 1. 3. The method according to claim 1, wherein the hydraulic stop operation of the variable valve mechanism in which the valve lift characteristic changes stepwise is delayed until the operating condition becomes a hydraulic stop condition after the detected oil temperature exceeds the set temperature. 3. The variable valve train for an internal combustion engine according to claim 2, wherein 4. The variable valve mechanism in which the valve lift characteristic changes continuously is a valve timing adjustment mechanism that changes the phase of a camshaft with respect to a crankshaft, and the valve lift characteristic changes stepwise. 4. The internal combustion engine according to claim 2, wherein the variable valve mechanism is a valve lift adjusting mechanism that selectively transmits a lift of one of a low-speed cam and a high-speed cam to an intake / exhaust valve. Variable valve gear. 5. A variable valve mechanism is provided for each of the intake valve and the exhaust valve, and the set temperature of the variable valve mechanism on the exhaust side is set lower than the set temperature of the variable valve mechanism on the intake side. The variable valve train for an internal combustion engine according to claim 1, wherein