JPH094424A - Variable valve gear for internal combustion engine - Google Patents

Abstract

PURPOSE: To reduce a valve jumping rate and promote exchange of operation oil. CONSTITUTION: A cam side plunger 8 is driven by a cam shaft 16, for pressurizing operation oil in a hydrauli chamber 10. An intake/exhaust valve 2 is opened by a hydraulic pressure in the hydraulic chamber 10. When a pilot valve 21 is opened during lifting the intake/exhaust valve 2, hydraulic pressure inside the hydraulic chamber 10 is released to an accumulator 20. The intake/exhaust valve 2 starts seating action. The operation oil stored in the accumulator 20 returns to the hydraulic chamber 10 when a cam lift of the cam shaft 16 is lowered. In high speed rotation area, an opening/closing valve 6 is opened for discharging a part of the operation oil in the hydraulic chamber 10 to the outside from a hydraulic pressure releasing passage 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake valve or an exhaust valve of an internal combustion engine (hereinafter, both are collectively referred to as intake and exhaust valves).
The present invention relates to a variable valve operating device for an internal combustion engine that variably controls the lift amount of the engine.

[0002]

2. Description of the Related Art A hydraulic variable valve operating device for variably controlling the lift of intake and exhaust valves of an internal combustion engine is disclosed in, for example, Japanese Patent Laid-Open No. 58-5.
It is disclosed in Japanese Patent No. 3615. This device pressurizes the hydraulic oil along the cam lift by reciprocating the cam side plunger by the cam shaft, and hydraulically drives the intake / exhaust valve by the pressurized hydraulic oil. A release valve that releases the pressurized hydraulic oil to the low pressure side is provided in the hydraulic oil supply path. When the release valve is opened during the lift of the intake / exhaust valve, the pressure of the hydraulic oil decreases, so that the intake / exhaust valve is switched to the seating operation from the middle of the lift by the urging force of the valve spring. That is, the lift amount of the intake / exhaust valve can be variably controlled by the opening timing of the release valve.

A structure in which hydraulic energy released by the release valve is absorbed by an accumulator to recover hydraulic energy is shown in, for example, SAE paper 930820. FIG. 6 shows the configuration of this conventional variable valve operating device, in which a cam side plunger 51 driven by a cam 50 pressurizes hydraulic oil in a hydraulic chamber 52, and the pressurized hydraulic oil causes the valve side plunger 51 to move. The intake / exhaust valve 54 is lifted via 53. The hydraulic chamber 52 and the accumulator 55 are connected via a hydraulic pressure release passage 56, and the release valve 5 is connected to the hydraulic pressure release passage 56.
7 is installed. The release valve 57 is opened by the pressure balance between the hydraulic chamber 52 and the back pressure chamber 57a, and a pilot valve 58, which is an electromagnetic valve, is provided to release the hydraulic pressure in the back pressure chamber 57a. Further, the accumulator 55 and the hydraulic chamber 52 are connected to each other in parallel with the hydraulic pressure release passage 56 via the hydraulic pressure introduction passage 59, and the hydraulic pressure introduction passage 69 has a reverse structure that allows only the inflow from the accumulator 55 to the hydraulic chamber 52. A stop valve 60 is interposed. Further, hydraulic oil is supplied to the accumulator 55 from the oil pump 62 via the check valve 61.

In such a structure, the high-pressure hydraulic oil discharged through the release valve 57 is introduced into the accumulator 55, and then the hydraulic pressure is introduced from the accumulator 55 when the lift amount of the cam 50 decreases. It is sent back to the hydraulic chamber 52 via the passage 56. Therefore, the energy once collected by the accumulator 55 is added to the driving force of the cam 50, and the energy can be effectively used as a whole.

Further, when a valve jump occurs during high speed rotation, hydraulic oil is replenished from the oil pump 62 by the volume expansion of the hydraulic chamber 52, but the pilot valve 58 opens the release valve 5.
Since the volume expansion of the hydraulic oil is released to the outside when the valve of 7 is opened,
The seating of the intake / exhaust valve 54 does not become incomplete. Furthermore, the replacement of hydraulic oil is promoted to prevent deterioration of hydraulic oil.

[0006]

However, in such a conventional configuration, the hydraulic oil is released to the outside only when the release valve 57 is opened, so that a surge pressure is generated when the lift of the cam 50 rises. It is not possible to reduce the valve jump amount of. In this case, the amount of cam lift plus the amount of lift increase due to valve jump is specified as the maximum lift, so the maximum lift cannot be reached in the rotation range where valve jump does not occur, and the shaft output of the engine decreases. Will be invited. Further, since the amount of hydraulic oil discharged from the pilot valve 58 is small, the effect of replacing the hydraulic oil cannot be expected so much.

An object of the present invention is to reduce the valve jump amount to improve the engine shaft output and to promote the replacement of hydraulic oil.

[0008]

A variable valve operating system for an internal combustion engine according to the present invention is driven by a camshaft and an intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring, and is provided in a hydraulic chamber. A cam side plunger that pressurizes hydraulic oil, a valve side plunger that operates to one side by the hydraulic pressure in the pressurized hydraulic chamber to lift the intake valve or the exhaust valve, an accumulator connected to the hydraulic chamber, and an accumulator Between the hydraulic chamber and the hydraulic chamber, and hydraulic releasing means for connecting the hydraulic chamber and the outside with hydraulic releasing means for releasing the hydraulic pressure in the hydraulic chamber to the accumulator during the lift of the intake valve or the exhaust valve. A passage and an on-off valve that opens the hydraulic release passage in the engine high speed rotation range to release a part of the hydraulic oil in the hydraulic chamber to the outside;
It is provided with.

According to the second aspect of the present invention, the hydraulic chambers of a plurality of cylinders are joined to the hydraulic pressure release passage via check valves, respectively, and one opening / closing valve is provided downstream thereof.

Further, in the invention of claim 3, the on-off valve is opened even at the time of starting.

Further, according to the invention of claim 4, an auxiliary oil pump for supplying hydraulic oil to the hydraulic chamber only at the time of starting and an electric motor for driving the oil pump are provided.

[0012]

When the cam shaft presses the cam side plunger, the hydraulic pressure in the hydraulic chamber increases, and the valve side plunger moves accordingly. In other words, the intake / exhaust valve lifts in a form corresponding to the hydraulic pressure. When the hydraulic pressure releasing means is actuated during this lift, the pressure in the hydraulic chamber is released to the accumulator in the low pressure state, and the intake / exhaust valve turns to the seating operation.
Therefore, the lift amount changes by changing the operation timing of the hydraulic pressure releasing means. The high-pressure hydraulic fluid that has flowed into the accumulator is pushed back into the hydraulic chamber as the cam lift decreases, and energy can be recovered.

In the high speed rotation range where surge pressure is generated, the open / close valve is opened. Even if surge pressure is generated when the cam lifts up in this state, part of the hydraulic oil in the hydraulic chamber is released to the outside through the hydraulic pressure release passage, so the surge pressure decreases faster and the valve jump amount decreases. . Further, the same amount of hydraulic oil as the released amount is supplied to the hydraulic chamber, and replacement of the hydraulic oil is promoted, so that the temperature rise of the hydraulic oil is prevented.

According to the second aspect of the invention, the hydraulic oil in the hydraulic chambers of the plurality of cylinders flows into the hydraulic pressure release passage through the check valve and is released to the outside when the opening / closing valve is opened.

Further, according to the third aspect of the invention, the air accumulated in the hydraulic chamber is discharged to the outside through the hydraulic pressure release passage at the time of starting, so that the startability of the engine is improved.

If an oil pump as claimed in claim 4 is separately provided, the supply of hydraulic oil at the time of start-up is further promoted, and air can be quickly evacuated.

[0017]

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

FIG. 1 is a sectional view of an essential part of an internal combustion engine showing a first embodiment of the present invention. An intake / exhaust valve 2 is slidably mounted on a cylinder head 1 and a valve spring 3 is used. Always biased in the closing direction. A housing 4 of the lift control unit is superposed on the upper surface of the cylinder head 1, and a valve side plunger 6 is slidably fitted in a cylinder 5 mounted on the lower surface side of the housing 4. The tip of the valve-side plunger 6 abuts on the stem end of the intake / exhaust valve 2, and the plunger 6 moves by hydraulic pressure to push open the intake / exhaust valve 2.

A cylinder 7 is mounted on the upper surface side of the housing 4, and a cam side plunger 8 is slidably arranged in the cylinder 7. The cam side plunger 8 is biased upward by a spring 9 housed in the cylinder 7. Hydraulic chamber 10 in cylinder 7
Is communicated with a hydraulic chamber in the cylinder 5 via a passage 11. The passage 11 is branched in the middle to open to the peripheral wall and the upper wall of the upper end portion of the cylinder 6. A check valve 12 and a damper chamber 13 are provided in an opening portion on the upper wall side of the passage 11, and an orifice 14 is provided in parallel with these. That is, the cam side plunger 8 is a crankshaft (not shown) of the internal combustion engine.
The cam 16 of the cam shaft 15 that rotates in synchronism with is driven via a rocker arm 17.
The camshaft 15 rotates to reciprocate to pressurize the hydraulic oil in the hydraulic chamber 10. Then, this pressurized oil pressure is introduced into the cylinder 5 via the check valve 12 and the damper chamber 13, and the valve side plunger 6 is pressed in the lift direction of the intake / exhaust valve 2.

Hydraulic oil is supplied to the hydraulic chamber 10 from a hydraulic oil supply passage 19 via a check valve 18. The hydraulic oil supply passage 19 is discharged from an oil pump (not shown). It communicates to the side. This hydraulic oil supply system is integrated with the engine lubricating system, and the engine lubricating oil is used as the hydraulic oil, and the lubricating oil pump mechanically driven by the engine output is also used as it is.

The housing 4 has an intake / exhaust valve 2
In order to variably control the lift amount of
An accumulator 20 that functions as a release valve and a pilot valve 21 that supplies a pilot pressure to the accumulator 20 are provided.

The accumulator 20 includes a cylinder 22.
It has a plunger 23 slidably disposed therein, which defines an accumulator chamber 24. The plunger 23 is biased by an accumulator spring 25 in a direction in which the accumulator chamber 24 contracts. The back pressure chamber 26 in which the accumulator spring 25 is housed is open to the atmosphere via a communication hole 27.

The accumulator 20 includes a hydraulic chamber 10
To the hydraulic pressure release passage 28. The tip of the hydraulic pressure release passage 28 opens toward the outer peripheral surface of the plunger 23, and is closed by the plunger 23 when the plunger 23 is not displaced, and communicates with the accumulator chamber 24 when the plunger 23 is displaced. It is supposed to do. The plunger 23 has a taper portion 23a on the accumulator chamber 24 side, and receives the biasing force of the accumulator spring 25 to press the taper portion 23a against the taper surface of the cylinder 22 to seal the hydraulic release passage 28 when closed. Has been done. A drain passage 30 is connected to the accumulator chamber 24 via an orifice 29, and the accumulator chamber 24 is opened to an oil pan 31 via the drain passage 30.
The diameter of the orifice 29 is such that even if high-pressure hydraulic oil leaks into the accumulator chamber 24 when the plunger 23 is not displaced,
The hydraulic pressure in the accumulator chamber 24 is set to a value as small as possible that does not cause the cracking pressure of the plunger 23. Further, the tip portion 30a of the drain passage 30 extends to the bottom portion of the oil pan 31 so that air is not sucked in. Therefore, for example, the plunger 2
3 through the contact surface between the cylinder 22 and the hydraulic release passage 28
Even if some of the hydraulic oil leaks, the inside of the accumulator chamber 24 is reliably kept at a low pressure.

On the other hand, in this embodiment, the pilot valve 21 is constituted by an ON / OFF type solenoid valve which opens and closes depending on the presence or absence of energization. That is, the pilot valve 21 is a needle-shaped valve body 3 slidably supported.
2, the valve body 32 is always biased by a spring in the valve closing direction, and a solenoid 33 is provided so as to bias the valve body 32 in the valve opening direction. The pilot valve 21 includes a hydraulic chamber 10 and an accumulator chamber 24.
The pilot pressure passage 34 connected to and is opened and closed. In particular, the hydraulic chamber 10 side portion of the pilot pressure passage 34 opens toward the side surface of the valve body 32 so that the high hydraulic pressure from the hydraulic chamber 10 does not act on the valve body 32 in the valve opening direction. Moreover, the portion on the accumulator chamber 24 side is open toward the tip of the valve body 32. Therefore, even if a high surge pressure is generated in the hydraulic chamber 10 when the cam lift rises, the pilot valve 21 will not open due to the influence of the surge pressure.

The valve body 32 receives a pressing force in the valve opening direction due to the hydraulic pressure in the accumulator chamber 24, and is pressed in the seating direction by the urging force of the spring 33 so as to oppose the pressing force. The biasing force of the spring is set so as to always exceed the pressing force in the lift direction by the hydraulic pressure of the accumulator chamber 24, and the valve body 32 is reliably held in the seated state when the energization of the solenoid 33 is stopped. Then, when the solenoid 33 is energized, the valve body 3 is magnetically attracted.
2 is sucked in the lift direction, and the valve body 32 is lifted by exceeding the biasing force of the spring. That is, in this embodiment, the pilot valve 21, the hydraulic pressure release passage 28, and the pilot pressure passage 34 constitute hydraulic pressure release means.

A hydraulic pressure release passage 35 branches off in the middle of the passage 11 connecting the hydraulic chamber 10 and the cylinder 5, and the tip of the passage 35 is open to the atmosphere on the upper surface of the housing 4. An on-off valve 36 is provided in the hydraulic pressure release passage 35. Like the pilot valve 21, the valve 36 is also an ON / OFF type solenoid valve that opens and closes depending on the presence or absence of energization. That is, as shown in FIG. 2, the on-off valve 36 has a needle-shaped valve body 37 slidably supported, and the valve body 37 is constantly urged by a spring 38 in the valve closing direction. A solenoid 39 is provided so as to bias the valve element 37 in the valve opening direction. In particular, the portion 35a of the hydraulic pressure release passage 35 on the hydraulic chamber 1010 side is opened toward the side surface of the valve body 37 so that the high hydraulic pressure from the hydraulic chamber 10 does not act on the valve body 37 in the valve opening direction. In addition, the portion 35b on the atmosphere open side is open toward the tip of the valve element 37. Therefore, even if a high surge pressure occurs in the hydraulic chamber 10 when the cam lift rises, the on-off valve 36 will not open due to the influence of the surge pressure. The valve body 37 closes the hydraulic pressure release passage 35 when the energization of the solenoid 39 is stopped, but when the solenoid 39 is energized, the valve body 37 is attracted to the left by the magnetic force to open the hydraulic pressure release passage 35. There is. In the hydraulic pressure release passage 35, in order to reduce the amount of hydraulic oil leaked as much as possible, the diameter of the portion 35b on the atmosphere opening side is set to the portion 3 on the hydraulic chamber side.
It is smaller than that of 5a.

The on-off valve 36 is controlled by a control unit (not shown), and is kept closed in the engine low speed rotation range and kept open in the engine high speed rotation range. Further, as will be described later, the open state is established even when the engine is started.

Next, the operation of the above embodiment will be described. When the cam side plunger 8 is pressed along with the lift of the cam 16, the hydraulic pressure in the hydraulic chamber 10 rises, and the valve side plunger 6 moves accordingly. That is, the lift of the intake / exhaust valve 2 is started. When the solenoid 33 of the pilot valve 21 is energized while the intake / exhaust valve 2 is being lifted by the pressurized hydraulic oil in the hydraulic chamber 10 as described above, the pilot valve 2
1 is opened and the hydraulic pressure in the hydraulic chamber 10 is changed to the pilot pressure passage 3
4 is introduced into the accumulator chamber 24 as pilot pressure. With this pilot pressure introduced,
Since the spring force and the pressure receiving area are set so that the pressing force by the hydraulic pressure in the accumulator chamber 24 exceeds the urging force by the accumulator spring 25, the plunger 23 is displaced upward while pressing the accumulator spring 25. As a result, the hydraulic pressure release passage 28 opens. That is, the tip of the hydraulic pressure release passage 28 and the accumulator chamber 24 are in communication with each other, and the hydraulic pressure in the hydraulic chamber 10 is
It is released to the accumulator chamber 24 in the low pressure state. Therefore, the intake / exhaust valve 2 switches to a seating operation during the lift. Here, since the plunger 23 is relatively large in order to secure the capacity required for the accumulator 20, the passage opening area of the hydraulic pressure release passage 31 can be secured sufficiently large when the plunger 23 is displaced. . Therefore, the energy loss when the hydraulic oil moves from the hydraulic chamber 10 to the accumulator chamber 24 is very small.

After that, when the lift of the cam 16 gradually decreases, the hydraulic oil stored in the accumulator chamber 24 is pushed back into the hydraulic chamber 10 through the hydraulic pressure release passage 28. This hydraulic energy contributes to the rotation of the camshaft 15, and energy is thereby recovered. In this way, when the hydraulic oil returns from the accumulator chamber 24 to the hydraulic chamber 10, there is no check valve in the path, so the energy loss becomes very small.

By the way, in the high-speed rotation range where the surge pressure is generated, the on-off valve 36 is controlled to be always open. In this state, even if surge pressure is generated when the lift of the cam 16 rises, a part of the hydraulic oil in the hydraulic chamber 10 is partially discharged from the hydraulic pressure release passage 35.
Since it is discharged to the outside through the surge pressure, the surge pressure decreases faster and the valve jump amount decreases. As the hydraulic oil is discharged, after the lift of the cam 16 is completed, the same amount of hydraulic oil is supplied from the oil pump to the hydraulic chamber 10 through the hydraulic oil supply passage 19.

Further, the plunger 2 of the accumulator 20
Even if some of the hydraulic oil leaks from the hydraulic pressure release passage 28 to the accumulator chamber 24 through the contact surface with the cylinder 22, the leaked hydraulic oil passes through the orifice 29 and the drain passage 30 and the oil pan 31
As a result, the inside of the accumulator chamber 24 is reliably kept at a low pressure. That is, there is no possibility that the plunger 23 of the accumulator 20 will malfunction due to leakage of hydraulic oil into the accumulator chamber 24.

Further, when the intake / exhaust valve 2 starts to lift, hydraulic oil is supplied into the cylinder 5 through the passage 11, the check valve 12, and the damper chamber 13, so that the hydraulic chamber 10 is lifted when the cam lift rises. Even if a high surge pressure occurs, the lift of the intake / exhaust valve 2 is gently started. Further, since the hydraulic oil is finally discharged from the cylinder 5 through the orifice 14, the intake / exhaust valve 2 is seated gently.

By the way, when the operation of the engine is stopped for a long time, the hydraulic oil in the hydraulic chamber 10 leaks to the outside from the clearance between the valve side plunger 6 and the cylinder 5, etc., and the air is accumulated in the hydraulic chamber 10. Sometimes. In this case, even if the plunger 8 is pushed by the cam 16 during cranking of the engine, the air in the hydraulic chamber is only compressed, and the intake / exhaust valve 2 does not lift correctly. Therefore, in this device, the opening / closing valve 36 is opened even when the engine is started to bleed the air from the hydraulic chamber 10. By doing so, the valve lift is quickly restored, and the engine is quickly started. In order to effectively remove air, the on-off valve 36
Should be installed at the top of the system.

Thus, according to the above embodiment, the cam 1
Since the hydraulic oil is released to the outside from the time when the lift of No. 6 rises, the surge pressure decreases faster, so the valve jump amount decreases. Therefore, the rotation region in which the intake / exhaust valve 2 can be lifted to the maximum is expanded, and the shaft output of the engine can be improved accordingly. Further, the replacement of the hydraulic oil is promoted, the temperature rise of the hydraulic oil due to the energy loss increase at the time of high speed rotation can be suppressed, and the deterioration of the hydraulic oil can be prevented.

Further, the hydraulic chamber 10 and the accumulator chamber 24
When the hydraulic oil reciprocates between and, the energy loss can be made very small, and the fuel consumption rate of the internal combustion engine can be improved accordingly. Further, the pilot valve 21 is configured separately from the accumulator 20, and only opens and closes the pilot pressure passage 35 having a relatively small passage area, so that the responsiveness does not deteriorate.

FIGS. 3 and 4 show a second embodiment in which the hydraulic pressure release passage 40 is shared with the hydraulic chambers 10 of a plurality of cylinders.
The other points are basically the same as those of the first embodiment.

In this embodiment, the hydraulic chambers 10 of a plurality of cylinders are joined to the hydraulic pressure release passage 40 via the check valves 41, respectively, and one opening / closing valve 42 is provided downstream thereof. In FIG. 4, 43 is an oil pump driven by engine output,
The hydraulic oil is pumped up from the oil pan 31, and the filter 44,
The oil is supplied to the hydraulic chamber 10 through the hydraulic pressure supply passage 19 and the check valve 18. In this case, the hydraulic chamber 1 is opened when the opening / closing valve 42 is opened.
The hydraulic oil in 0 flows into the hydraulic pressure release passage 40, and the on-off valve 42
Is discharged to the outside through the check valve 41, but is prevented from flowing into the hydraulic chamber 10 of another cylinder. By doing so, only one on-off valve 42 is required, which is advantageous in terms of cost.

FIG. 5 shows a third embodiment in which an electric type auxiliary oil pump 45 which operates only at the time of starting is separately provided. In this embodiment, the auxiliary oil pump 45 is connected to the check valve 4
The oil pump 43 is connected in parallel via 6, 47, and the oil pump 45 is driven by a motor 46. That is, the rotation speed of the oil pump 43 is low at the time of cranking, and although it takes a considerable time to send the hydraulic oil to the hydraulic chambers 10 of the respective cylinders by the oil pump 43 alone, the auxiliary oil pump 45 dedicated to the start is used. Since the hydraulic oil is provided, even if the lubricating oil pressure is low during cranking, it is possible to secure a sufficient oil supply pressure and quickly supply the hydraulic oil to each hydraulic chamber 10. The check valve 47 prevents the working oil from escaping to the oil pump 43 side. in this case,
The air in each hydraulic chamber 10 is quickly evacuated, and the startability of the engine is further improved. Further, since the oil pump 45 may be operated only at the time of starting, it is possible to have a cheaper configuration in terms of durability and capacity as compared with the oil pump 43 which is constantly operated.

In each of the above embodiments, the on-off valve 36 is always opened in the high speed rotation range, but it may be opened only when the lift of the cam 16 rises. Further, the on-off valve 36 is not limited to the electromagnetic configuration as shown in each of the above-mentioned embodiments, but may be of a system that variably controls the opening amount. In addition, the pilot valve 21
It suffices that the pilot pressure be simply applied in a pulsed manner to the accumulator chamber 24, and it is not limited to the electromagnetic configuration as shown in each of the above embodiments.

[0040]

As is apparent from the above description, claim 1
In the variable valve operating device for an internal combustion engine according to the present invention, the valve jump amount is reduced, the rotation region in which the intake / exhaust valve can be lifted maximum is expanded, and the shaft output of the engine can be improved accordingly. Furthermore, replacement of the hydraulic oil in the hydraulic chamber is promoted, and deterioration of the hydraulic oil can be prevented.

Further, when the hydraulic pressure release passage is arranged as in claim 2, only one on-off valve is required, which is advantageous in cost.

If the open / close valve is opened at the time of starting as in the third aspect, the air in the hydraulic chamber is bleeded and the startability of the engine is improved.

If the oil pump according to the fourth aspect is separately provided, a sufficient hydraulic pressure can be secured even at the time of starting, air can be quickly removed, and the startability of the engine is further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a variable valve operating device according to the present invention.

FIG. 2 is an enlarged view of the on-off valve of FIG.

FIG. 3 is a sectional view showing a second embodiment.

FIG. 4 is a diagram showing a hydraulic system of a second embodiment.

FIG. 5 is a diagram showing a hydraulic system of a third embodiment.

FIG. 6 is a structural explanatory view showing a structure of a conventional variable valve operating device.

[Explanation of symbols]

 2 ... Intake / exhaust valve 6 ... Valve side plunger 8 ... Cam side plunger 9 ... Valve spring 10 ... Hydraulic chamber 15 ... Cam shaft 20 ... Accumulator 21 ... Pilot valve 28 ... Hydraulic release passage 34 ... Pilot pressure passage 35 ... Hydraulic release passage 36 … Open / close valve

Claims (4)

[Claims] 1. An intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring, a cam side plunger which is driven by a cam shaft and pressurizes hydraulic oil in a hydraulic chamber, and the pressurized hydraulic chamber. It moves to one side by the hydraulic pressure of
A valve-side plunger that lifts the intake valve or the exhaust valve, an accumulator connected to the hydraulic chamber, an accumulator that is interposed between the accumulator and the hydraulic chamber, and the lift valve of the intake valve or the exhaust valve is lifted. A hydraulic release means for releasing the hydraulic pressure in the hydraulic chamber to the accumulator, a hydraulic release passage connecting the hydraulic chamber and the outside, and a part of the hydraulic fluid in the hydraulic chamber opened by opening the hydraulic release passage in the engine high speed rotation range. A variable valve operating system for an internal combustion engine, comprising: 2. The internal combustion engine according to claim 1, wherein the hydraulic chambers of the plurality of cylinders are joined to the hydraulic pressure release passage via check valves, respectively, and one opening / closing valve is provided downstream thereof. Variable valve device. 3. The variable valve operating system for an internal combustion engine according to claim 1, wherein the on-off valve is opened even at the time of starting. 4. The variable operation of an internal combustion engine according to claim 3, wherein an auxiliary oil pump for supplying hydraulic oil only to the hydraulic chamber at the time of starting and an electric motor for driving the oil pump are provided. Valve device.