JPH07180516A - Variable valve gear for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce calculation load on a microcomputer and prevent a valve lift amount and a lift interval from becoming short by surge pressure in high speed range. CONSTITUTION:An intake valve 1 provided with a valve spring 2 is interconnected to a valve side plunger 3, and lifted by the pressure of hydraulic oil pressurized by a cam side plunger 6. Also a release valve 21 to control the lift amount is provide with a main valve element 25 and a pilot valve element 35, and the pilot valve element 35 is pressed by the hydraulic oil inside a back pressure chamber 29 in the direction of lifting and also pressed by a pilot spring 37 and the magnetic force of a solenoid 38 in the seating direction. When the pressure of hydraulic oil increases and it lifts the valve by a specified amount, pressing pressure from the back pressure chamber 29 exceeds that by the solenoid 38 and the like. Therefore the pilot valve element 35 lifts and, at the same time, the main valve element 25 opens. In addition, lubricating oil pressure is introduced into an auxiliary hydraulic pressure chamber 41 so as to resist surge pressure in high speed range.

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 a lift amount of intake and exhaust valves of an internal combustion engine is disclosed in, for example, Japanese Unexamined Patent Publication No. 1-13.
No. 4013 is disclosed. This device is driven by a cam shaft to reciprocate, and moves forward and backward by a cam side plunger that pressurizes hydraulic oil during its forward movement, and hydraulic oil pressurized by this cam side plunger, and lifts intake and exhaust valves. It is equipped with a valve side plunger and a release valve that releases the hydraulic oil pressurized by the cam side plunger to the low pressure side.If the release valve is opened during the lift of the intake / exhaust valve, the pressurized hydraulic oil Is released to the low pressure side, so that the intake / exhaust valve turns into a seating operation from the middle of the lift together with the valve side plunger 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.

Here, the release valve is a main valve body that directly opens and closes a passage extending from a high pressure chamber compressed by a cam side plunger to a low pressure side, and a solenoid valve type pilot valve that controls opening and closing of the main valve body. When the pilot valve body is opened, the balance of the hydraulic pressure acting on the front and rear of the main valve body is lost and the main valve body is lifted. And
The opening / closing operation of the pilot valve body is directly controlled by a solenoid. That is, the pilot valve body is kept closed while the solenoid is energized, and when the solenoid is de-energized, the pilot valve body is lifted in the opening direction. Therefore, the lift amount of the intake / exhaust valve is actually controlled by the energization stop timing for the solenoid, and the control unit including a microcomputer determines the optimum energization stop timing based on the rotation speed and load of the internal combustion engine. The lift amount is variably controlled by sequentially calculating.

[0004]

However, in the above-mentioned conventional variable valve operating system, the energization stop timing must be calculated and controlled for each cycle of each cylinder, so that the amount of calculation and the speed of calculation of the microcomputer must be reduced. There is a problem that the load is heavy above. In particular, in a multi-cylinder internal combustion engine, there is a phase difference between the lift timings of the intake and exhaust valves of each cylinder, so it is necessary to calculate the energization stop timing for the solenoid for each cylinder, and complicated calculations must be performed in large numbers. I won't.

Further, in the hydraulic variable valve operating device as described above, when the engine speed is increased, the acceleration of the cam side plunger driven by the cam shaft is increased, and a very high protrusion is generated when the valve lift is started. Although pressure, so-called surge pressure is generated, if the pilot valve body is lifted by this surge pressure, the lift amount and lift period of the intake / exhaust valve are significantly insufficient. Therefore, a large solenoid is required to withstand the surge pressure in the high speed range, resulting in large power consumption.

[0006]

Therefore, according to the present invention,
By applying the pressing force to the pilot valve body so that it balances with the hydraulic oil pressure, the release valve operates due to the hydraulic pressure change that is correlated with the lift amount, and the surge pressure is counteracted by the auxiliary hydraulic pressure. did. That is, the invention according to claim 1 is such that the intake valve or the exhaust valve which is always biased in the closing direction by the valve spring, the cam side plunger which is driven by the cam shaft and pressurizes the hydraulic oil, and the cam side plunger. A valve-side plunger that operates in one direction by the pressurized hydraulic oil to lift the intake valve or the exhaust valve, and a release valve that releases the hydraulic oil pressurized by the cam-side plunger to a low pressure side. In a variable valve operating system for an internal combustion engine, the release valve releases hydraulic oil to a low pressure side by lifting from the main valve seat, and also sits on the main valve seat against the pressing force of the pressurized hydraulic oil. In this state, the main valve element that shuts off the hydraulic oil to the low pressure side and the pressurized hydraulic oil are introduced through the orifice,
The back pressure chamber that urges the main valve element in the seating direction by the hydraulic pressure of the introduced hydraulic fluid, and the back pressure chamber that is released to the low pressure side by lifting from the pilot valve seat, and in the seated state, the back pressure chamber A pilot valve body that shuts off the pressure chamber from the low pressure side, and receives the hydraulic pressure of the back pressure chamber in the lift direction, and an auxiliary hydraulic pressure that presses the pilot valve body toward the seating direction by an auxiliary hydraulic pressure introduced from the outside. The pressure in the seating direction of the pilot valve body so that the pilot valve body lifts when the hydraulic pressure of the chamber and the back pressure chamber reaches a hydraulic pressure corresponding to a desired lift amount. And a solenoid to be applied.

In the second aspect of the invention, the lubricating oil pressure generated by the oil pump of the internal combustion engine is used as the auxiliary oil pressure. Further, in the third aspect of the present invention, the control pressure obtained by further adjusting the hydraulic pressure generated by the oil pump of the internal combustion engine is used as the auxiliary hydraulic pressure.

Further, according to the invention of claim 4, an opening / closing valve is provided in the hydraulic pressure introduction path to the auxiliary hydraulic chamber so that the auxiliary hydraulic chamber is closed when the engine speed is equal to or higher than a predetermined value.

Further, in the invention according to claim 5, the pressure of the hydraulic oil is prevented from escaping to the accumulator even if the pilot valve body is lifted by the surge pressure. That is, the invention according to claim 5 is an operating oil which is driven by a camshaft and an intake valve or an exhaust valve which is always biased in a closing direction by a valve spring, and which is introduced from an oil pump through a check valve and an accumulator. The cam side plunger that pressurizes the valve and the valve side plunger that operates to one side by the hydraulic oil pressurized by the cam side plunger to lift the intake valve or the exhaust valve, and the hydraulic oil that is pressurized by the cam side plunger. In a variable valve operating system for an internal combustion engine, comprising: a release valve that releases to the accumulator, the release valve releases hydraulic oil to the accumulator side by lifting from a main valve seat, and a pressurized operation In the state where it is seated on the main valve seat against the pressing force of the oil, the main valve element that shuts off the hydraulic oil from the accumulator side and the pressurized work Oil is introduced through the orifice, and the hydraulic pressure of the introduced hydraulic oil releases the back pressure chamber to the accumulator side by lifting it from the pilot valve seat and the back pressure chamber that urges the main valve element in the seating direction. In addition, while shutting off the back pressure chamber against the accumulator side in the seated state, the pilot valve body that receives the hydraulic pressure of the back pressure chamber in the lift direction and the hydraulic pressure of the back pressure chamber correspond to the desired lift amount. A solenoid that variably applies a pressing force to the pilot valve body in the seating direction so that the pilot valve body lifts when the hydraulic pressure is reached. It is characterized in that an oil chamber is formed in the engine and an on-off valve is provided to close the oil chamber when the engine speed is equal to or higher than a predetermined value.

[0010]

When the cam side plunger is pressed by the cam shaft, the hydraulic pressure in the hydraulic path to the valve side plunger increases, and the valve side plunger moves accordingly. That is,
The intake / exhaust valve lifts according to the hydraulic pressure. When the hydraulic pressure of the hydraulic oil thus rises, the hydraulic pressure in the back pressure chamber introduced via the orifice also rises. When the pressing force by the hydraulic pressure in the back pressure chamber exceeds the pressing force on the pilot valve body that is variably set by the solenoid, the pilot valve body lifts and releases the back pressure chamber to the low pressure side. Along with this, the main valve body is also lifted, and the hydraulic pressure of the hydraulic oil supplied to the valve side plunger is released to the low pressure side such as the accumulator. As a result, the intake / exhaust valve turns to the seating operation. When the pressing force is changed by the solenoid, the opening timing of the pilot valve body and the main valve body is changed, that is, the lift amount of the intake / exhaust valve is changed.

In the high speed region of the engine, a high surge pressure is generated in the early stage of lift of the intake / exhaust valve, but the pilot valve body is not lifted by the surge pressure because the auxiliary hydraulic pressure acts in the seating direction. .

If the lubricating oil pressure is used as the auxiliary oil pressure, the auxiliary oil pressure has a characteristic of increasing in the high engine speed range, and therefore it is possible to directly cope with the surge pressure increasing in the engine high speed side.

If the control pressure regulated as described in claim 3 is used as the auxiliary hydraulic pressure, variations in the auxiliary hydraulic pressure are reduced.

In the fourth aspect, the auxiliary hydraulic chamber is closed in the high speed region of the engine where surge pressure is a problem. As a result, the pilot valve body is fixed and lift of the pilot valve body due to surge pressure is prevented.

On the other hand, according to the fifth aspect of the invention, the accumulator is substantially fixed by closing the oil chamber behind the accumulator in the high speed region of the engine. Therefore, even if the pilot valve body and the main valve body are lifted by the surge pressure, the pressure of the hydraulic oil acting on the valve side plunger does not decrease. Therefore, the valve lift characteristic corresponds to the cam lift.

[0016]

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 diagram in which the present invention is applied to an intake valve of an internal combustion engine, and a pair of intake valves 1 is provided for each cylinder. The intake valve 1 is slidably mounted on a cylinder head (not shown), is constantly urged in a closing direction by a valve spring 2, and is pushed so as to open in the lift direction. A valve side plunger 3 is provided. Each valve-side plunger 3 is slidably fitted in the cylinder 4 and forms a hydraulic chamber 5.

A cam side plunger 6 is provided for each cylinder. This cam side plunger 6 is a cylinder 7
A high pressure chamber 8 is formed by being slidably fitted therein. The cam side plunger 6 is attached to a cam 9a of a cam shaft 9 which rotates in synchronization with a crank shaft (not shown) of the internal combustion engine.
It is driven via a rocker arm 10, and reciprocates when the cam shaft 9 rotates to pressurize the hydraulic oil in the high pressure chamber 8. The high pressure chamber 8 is connected to a pair of hydraulic chambers 5 corresponding to the intake valves 1 via a pair of hydraulic circuits 11 and 12, respectively.

The hydraulic oil is supplied to the high pressure chamber 8 of the cam side plunger 6 from an accumulator 16 via a check valve 17, and the accumulator 16 via a filter 18 and a check valve 19. It communicates with the discharge side of the oil pump 13. This hydraulic system is integrated with the engine lubricating system, and the engine lubricating oil is used as the operating oil, and the lubricating oil pump 13 mechanically driven by the engine output is also used as it is. Further, the accumulator 16 and the like do not have to be provided for each high pressure chamber 8, and can be shared by the entire engine, for example.

The hydraulic oil pressurized by the cam-side plunger 6 (hereinafter referred to as "pressurized hydraulic oil") is sent to each hydraulic chamber 5, whereby the valve-side plunger 3 operates in one direction, so that the intake valve 1 Lifts against the reaction force of the valve spring 2. Particularly, since the intake valve 1 is lifted to a position where the hydraulic pressure in the hydraulic chamber 5 and the reaction force of the valve spring 2 are balanced, if the engine speed is constant, the lift amount is determined in a form corresponding to the hydraulic pressure.

In order to variably control the lift amount of the intake valve 1 according to operating conditions and the like, a release valve 21 is provided between the high pressure chamber 8 and the low pressure side accumulator 16.
That is, the hydraulic circuit 14 having the check valve 17 is provided in parallel with the hydraulic circuit 15, and the release valve 21 is provided in the hydraulic circuit 15. The release valve 21 includes a main valve mechanism 22 and a pilot valve mechanism 23.

The main valve mechanism 22 is for directly opening and closing the oil passage between the high pressure chamber 8 and the accumulator 16, and the bottomed cylindrical main valve body 25 is slidable in the cylinder 24. It is fitted. The main valve body 25 shuts off between the high pressure chamber 8 and the accumulator 16 by seating the substantially conical tip portion on the main valve seat 26, and when the main valve body 25 lifts. , Both are in communication. Specifically, the first oil chamber 2 is exposed to the tip of the main valve body 25.
7 and the second oil chamber 28 in an annular shape via the main valve seat 26,
The first oil chamber 27 communicates with the high pressure chamber 8 side, and the second oil chamber 28 communicates with the accumulator 16 side. In addition, as opposed to the first oil chamber 27,
A back pressure chamber 29 is defined between the main valve body 25 and the bottom of the cylinder 24. The back pressure chamber 29 communicates with the first oil chamber 27 via an orifice 30 formed at the tip of the main valve body 25. That is, the pressurized hydraulic oil is introduced from the high pressure chamber 8 side through the orifice 30.

Lifting and seating of the main valve body 25 are mainly performed by the pressure balance of the pressurized hydraulic oil. That is, the main valve body 25 is pressed by the pressurized hydraulic oil in the first oil chamber 27 in a direction of lifting from the main valve seat 26 (hereinafter, referred to as a lift direction), while being introduced into the back pressure chamber 29. The pressurized hydraulic oil is pressed in a direction in which the main valve seat 26 is seated (hereinafter referred to as a seating direction). The main valve body 25 is also pressed in the seating direction by the main valve spring 31, but the pressing force of this main valve spring 31 is neglected compared to the pressing force of the hydraulic oil in the back pressure chamber 29. Small enough to get.

The pressure of the pressurized hydraulic oil (the pressure in the first oil chamber 27) is P1, the pressure of the hydraulic oil in the back pressure chamber 29 is P2, and the first oil chamber 27 of the main valve body 25 when seated is exposed. When the pressure receiving area is S1 and the pressure receiving area of the main valve body 25 with respect to the back pressure chamber 29 (= the cross-sectional area of the main valve body 25) is S2, the pressing force F1 against the main valve body 25 in the lift direction and the pressing force toward the seating direction are given. When the pressing force of the main valve spring 31 is ignored, the pressure F2 is F1 = P1 · S1 F2 = P2 · S2.

Here, the pressure receiving areas have a relationship of S1 <S2, as is apparent from FIG. Therefore, P1 = P
If 2, then F1 <F2 and the main valve body 25 continues to sit. On the other hand, the pressure of the hydraulic oil in the back pressure chamber 29 decreases,
When F1> F2, the main valve body 25 lifts from the main valve seat 26.

As will be described later, P1 = P2 when the main valve body 25 is seated and the back pressure chamber 29 is shut off from the low pressure side.

Next, the pilot valve mechanism 23 will be described. First, the principle of control of the lift amount by the pilot valve mechanism 23 will be described. When the cam side plunger 6 starts to move forward, the pressure P1 of the hydraulic oil increases with the forward movement, whereby the valve side plunger 3 moves forward. The intake valve 1 is lifted by moving. In this case, as described above, when the engine speed is constant, the pressure P1 of the pressurized hydraulic oil and the lift amount of the intake valve 1 have a correspondence relationship. Therefore, the pressure P of the pressurized hydraulic oil
It is possible to control the lift amount of the intake valve 1 based on 1, that is, to control the lift amount of the intake valve 1,
The main valve body 25 may be opened (lifted) when the pressure P1 of the pressurized hydraulic oil reaches a pressure corresponding to a desired lift amount. Especially when the main valve body 25 is seated, the back pressure chamber 2
Since the pressure P2 of the working oil 9 is the same as the pressure P1 of the pressurized working oil, the valve opening timing of the main valve body 25 can be controlled by the pressure P2 of the working oil in the back pressure chamber 29.

From the above, according to the present invention, the pilot valve mechanism 23 is not ON / OFF controlled from the outside, but the pressure P2 of the working oil in the back pressure chamber 29 is set to a pressure corresponding to a desired lift amount. When this happens, the pilot valve mechanism 23 is automatically opened to lift the main valve body 25. As the pilot valve mechanism 23, an electromagnetic proportional control valve is used in this embodiment. That is,
This pilot valve mechanism 23 is a housing (not shown)
Needle-shaped pilot valve body 3 slidably supported on the
5, the pilot valve element 35 has a pilot valve seat 3
In the state of being seated on the valve 6, the back pressure chamber 29 and the accumulator 16 are cut off from each other, and when the pilot valve body 35 is lifted from the pilot valve seat 36, the two communicate with each other.

The pilot valve body 35 has the pilot valve seat 3
In the state where the pilot seat 6 is seated, the hydraulic pressure in the back pressure chamber 29 acting through the pilot valve seat 36 pushes the pilot valve seat 36 in a direction of lifting the pilot valve seat 36, while the urging force of the pilot spring 37 and the magnetic force of the solenoid 38 cause the pilot to move. It is pressed in the direction of seating on the valve seat 36. The magnetic force of the solenoid 38 is proportional to the magnitude of the current. Further, in this embodiment, the piston portion 39 is provided at the base end of the pilot valve body 35, and the piston portion 39 is fitted into the auxiliary cylinder 40 to form the auxiliary hydraulic chamber 41. . The auxiliary hydraulic chamber 41 is connected to the oil pump 13 via the hydraulic circuit 42 on the upstream side of the check valve 19, and the lubricating hydraulic pressure is introduced from the oil pump 13.

That is, assuming that the pressure receiving area of the pilot valve body 35 against the hydraulic oil when seated is S3, the pilot valve body 35 is pressed in the lift direction with the pressing force F3 = P2.S3. Further, when the pressing force of the pilot spring 37 is F4, the magnetic force of the solenoid 38 is F5, and the pressing force of the hydraulic pressure in the auxiliary hydraulic chamber 41 is F6, the pilot valve body 35 is pressed in the seating direction with the pressing force (F4 + F5 + F6). Has been done. Therefore, the pilot valve body 35
Keeps sitting if F3 <(F4 + F5 + F6),
When F3> (F4 + F5 + F6), pilot valve seat 3
Lift from 6.

Here, the magnetic force of the solenoid 38 is proportional to the magnitude of the current, and therefore the pressing force F5 and thus the pressing force (F4 + F5) can be variably controlled by controlling the current. Further, the lubricating oil pressure by the oil pump 13 becomes high (almost constant due to the valve opening pressure of the relief valve (not shown)) as the engine speed increases, so the pressing force F6 depends on the engine speed. It becomes a thing.

The pressing force F4 of the pilot spring 37 and the magnitude of the magnetic force of the solenoid 38 are set as follows. That is, when the internal combustion engine is idle, the solenoid 38 is de-energized and its magnetic force becomes zero.
Therefore, at this time, the pressing force F of the pilot spring 37 is
4 and the pressing force F6 of the lubricating oil pressure causes the pilot valve element 35
Therefore, the pressing force F4 of the pilot spring 37 is controlled to a predetermined value when the intake valve 1 reaches a required lift amount during idling, that is, when the pressure P1 of the pressurized hydraulic oil corresponds to idling. The size is set so that the pilot valve body 35 opens when the pressure reaches.

On the other hand, during the operation other than idling, the solenoid 38 is appropriately energized, and the magnetic force thereof controls the opening / closing of the pilot valve body 35. That is, the intake valve 1 is lifted by a desired amount, and the pressure P1 (=
When P2) reaches the desired pressure, F3> (F4 + F
The magnetic force of the solenoid 38 is adjusted so as to be 5 + F6). Specifically, the magnitude of the current supplied to the solenoid 38 is calculated and controlled by a control unit (not shown) using a microcomputer, based on operating conditions such as the rotation speed and load of the internal combustion engine.

When the solenoid 38 is energized with a maximum set current (set to about 70 to 80% of the maximum allowable current of the solenoid 38), even if the pressure of the pressurized hydraulic oil is maximized, the pilot The valve body 35 cannot be lifted.

Next, the operation of the above configuration will be described. When the cam shaft 9 rotates, the cam shaft 9 is driven by this and the cam side plunger 6 reciprocates. The cam side plunger 6 pressurizes the hydraulic oil in the high pressure chamber 8 at the time of its forward movement, and supplies it to the hydraulic chamber 5 on the intake valve 1 side. The valve-side plunger 3 is moved forward by this pressurized hydraulic oil, and the intake valve 1 is lifted together with this.

If F3 <(F4 + F5 + F6) during the entire lift period of the intake valve 1, the intake valve 1
Lifts along the cam profile of the camshaft 9. That is, the cam 9a is lifted to the maximum lift amount determined by the shape of the cam 9a, and then seated by the urging force of the valve spring 2.

On the other hand, during the lift of the intake valve 1, F3
If the magnetic force of the solenoid 38 is set so that> (F4 + F5 + F6), the pilot valve body 35 lifts during the lift of the intake valve 1 and releases the hydraulic oil in the back pressure chamber 29 to the accumulator 16 side. . As a result, the back pressure chamber 2
The pressure P2 of the hydraulic oil in 9 decreases, and the pressing force F1 acting on the main valve body 25 from the inside of the first oil chamber 27 is smaller than the pressing force F2 acting on the main valve body 25 from inside the back pressure chamber 29. It becomes relatively large. Therefore, the main valve body 25 lifts and releases the pressurized hydraulic oil to the accumulator 16 side. As a result, the pressure of the pressurized hydraulic oil in the high-pressure chamber 8 decreases, and the intake valve 1 is switched to the seating operation from the middle of the lift by the urging force of the valve spring 2. FIG. 2 shows the lift characteristic (solid line) in the case where the pressurized hydraulic oil is released to the low pressure side during the lift in this way, together with the cam lift characteristic (broken line).

As described above, in the variable valve operating device having the above structure, the intake valve 1 automatically starts the seating operation after being lifted by the desired amount, and the solenoid 38 is controlled to be turned on and off for each cycle. You don't have to. That is, in the microcomputer, it is not necessary to calculate the energization stop timing for each cycle, and only the energization amount for the solenoid 38 needs to be calculated and controlled.

On the other hand, in the high speed region of the engine, as described above, the acceleration of the cam side plunger 6 is increased, so that a surge pressure which is projected at the initial stage of the valve lift is generated. With respect to this surge pressure, in the above configuration, since the auxiliary hydraulic pressure is applied to the pilot valve body 35 in the seating direction by the auxiliary hydraulic pressure chamber 41, the lift due to the surge pressure is prevented even if the magnetic force of the solenoid 38 is relatively small. It In particular,
Since the lubricating oil pressure, which is the auxiliary oil pressure, becomes higher in the engine high speed range, it is possible to reliably counteract the surge pressure that becomes high in the high speed range without special pressure correction. Therefore, the solenoid 38 does not need to be unnecessarily increased in size, which is advantageous in terms of power consumption.

Although not shown, a hydraulic control valve such as a relief valve or a duty control valve is interposed between the oil pump 13 which is a hydraulic pressure source and the auxiliary hydraulic chamber 41 to adjust the pressure to a desired pressure. After that, it may be configured to be introduced into the auxiliary hydraulic chamber 41. The lubricating oil pressure generated by the oil pump 13 has variations due to individual differences and variations due to mixing of oil temperature or air. However, if the pressure is adjusted by interposing a hydraulic control valve, the influence of such variations can be eliminated. .

In the above embodiment, the pressurized hydraulic oil and the hydraulic oil in the back pressure chamber 29 are released to the accumulator 16, but they may be released to the atmospheric pressure. However, if it is released to the accumulator 16 as in the above embodiment, the pressure energy of the hydraulic oil can be recovered, which is advantageous in terms of fuel consumption rate.

Next, FIG. 3 shows an embodiment in which an opening / closing valve 43 made of a solenoid valve is provided in a hydraulic circuit 42 extending from the oil pump 13 to the auxiliary hydraulic chamber 41. The on-off valve 43 is controlled to be opened / closed by a control unit (not shown) based on the engine speed, and is kept open when the engine speed is low, and when the engine speed is equal to or higher than a predetermined speed, It is switched to the closed state. That is, in the low / medium speed range of the engine, the lubricating oil pressure is used as an auxiliary oil pressure.
1 and presses the pilot valve element 35 in the seating direction so as to counter the surge pressure. Then, particularly in the high speed range where the surge pressure is a problem, the opening / closing valve 43 is closed to close the auxiliary hydraulic chamber 41 in a state in which the hydraulic oil is sealed.
Therefore, the pilot valve body 35 is fixed, and even if a large surge pressure is applied, the pilot valve body 35
Is surely prevented from lifting.

Next, the embodiment shown in FIG. 4 does not prevent the lift of the pilot valve body 35 due to surge pressure, but rather
In the engine high speed range, the valve lift is configured to continue even if the main valve body 25 is lifted. In this embodiment, the pilot valve mechanism 23 is not provided with the auxiliary hydraulic chamber 41. Therefore, the force pressing the pilot valve element 35 in the seating direction is equal to the biasing force F4 of the pilot spring 37,
The sum of the magnetic force F5 of the solenoid 38 is (F4 + F5), which is in balance with the pressing force F3 by the pressurized hydraulic oil. On the other hand, the accumulator 16 whose pressurized hydraulic oil is released via the release valve 21 is
For example, a piston 16a is provided as a movable member that separates c, and the piston 16a is biased by a return spring 16b. An oil chamber 44 is provided behind the piston 16a, that is, on the return spring 16b side. , The oil chamber 44 is connected to the check valve 1 via the hydraulic circuit 45.
9 is connected to the oil pump 13 on the upstream side. Further, the hydraulic circuit 45 is provided with an opening / closing valve 46 which is an electromagnetic valve which is closed only in a region of a predetermined engine speed or higher.

In the above structure, the opening / closing valve 46 is closed and the oil chamber 44 behind the accumulator 16 is closed while the working oil is sealed in the high speed region of the engine where surge pressure is a problem. That is, the piston 16 of the accumulator 16
a is fixed. Therefore, even if the release valve 21 opens due to the surge pressure, the decrease in pressure due to the opening of the release valve 21 is suppressed. Therefore, irrespective of the opening of the release valve 21, the valve lift is continuously performed and the intake valve 1 operates along the cam lift. Therefore, the valve lift amount and the lift period do not become insufficient in the high speed range. Further, it is not necessary to make the solenoid excessively large.

With this construction, some variation in the hydraulic pressure introduced into the oil chamber 44 does not cause any problem. Therefore,
It is of course possible to further adjust the lubricating oil pressure and introduce it into the oil pressure 44, but there is no great difference compared with the case where the lubricating oil pressure is introduced as it is.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made.

For example, although the present invention is applied to the opening / closing control of the intake valve 1 in the above embodiment, it can be used for the opening / closing control of the exhaust valve as a matter of course.

[0048]

As is apparent from the above description, according to the present invention, the seating operation is automatically started when the intake / exhaust valve is lifted by a desired amount, and the pilot valve mechanism is externally operated. There is no need to control ON / OFF for each cycle. Therefore, the calculation load on the microcomputer is significantly reduced. Further, there is no influence of surge pressure that increases in the engine high speed range, and the valve lift amount and lift period do not decrease in the high speed range even if the solenoid is not oversized. Therefore, the weight of the device and the power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the invention according to claim 1;

FIG. 2 is a characteristic diagram showing valve lift characteristics in this embodiment.

FIG. 3 is a structural explanatory view showing a different embodiment.

FIG. 4 is a structural explanatory view showing an embodiment of the invention according to claim 5;

[Explanation of symbols]

 1 ... Intake valve 2 ... Valve spring 3 ... Valve side plunger 6 ... Cam side plunger 13 ... Oil pump 16 ... Accumulator (low pressure side) 21 ... Release valve 25 ... Main valve body 29 ... Back pressure chamber 35 ... Pilot valve body 37 ... Pilot spring 38 ... Solenoid 41 ... Auxiliary hydraulic chamber 43 ... Open / close valve 44 ... Oil chamber 46 ... Open / close valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inoguchi Iwane Iwane, Takara-cho, Kanagawa-ku, Yokohama, Kanagawa 2 Nissan Motor Co., Ltd. Formula company Zexel Higashimatsuyama factory (72) Inventor Akifumi Tagami 3-13-26, Yasumimachi, Higashimatsuyama city, Saitama Stock company Zexel Higashimatsuyama factory

Claims (5)

[Claims] 1. An intake valve or an exhaust valve which is constantly biased in a closing direction by a valve spring, a cam side plunger which is driven by a cam shaft and pressurizes hydraulic oil, and hydraulic oil which is pressurized by the cam side plunger. The variable operation of the internal combustion engine includes a valve-side plunger that operates in one direction to lift the intake valve or the exhaust valve, and a release valve that releases the hydraulic oil pressurized by the cam-side plunger to the low pressure side. In the valve device, the release valve lifts from the main valve seat to release the hydraulic oil to the low pressure side, and when the release valve is seated on the main valve seat against the pressing force of the pressurized hydraulic oil, the hydraulic oil is released. Main valve element that shuts off the low pressure side to the low pressure side, and a back pressure chamber that pressurizes hydraulic oil through an orifice and urges the main valve element in the seating direction by the hydraulic pressure of the introduced hydraulic oil. A pilot that releases the back pressure chamber to the low pressure side by lifting from the pilot valve seat and shuts off the back pressure chamber from the low pressure side when seated and receives the hydraulic pressure of the back pressure chamber in the lift direction. A valve body, an auxiliary hydraulic chamber for pushing the pilot valve body toward the seating direction by an auxiliary hydraulic pressure introduced from the outside, and a hydraulic pressure in the back pressure chamber when the hydraulic pressure reaches a hydraulic pressure corresponding to a desired lift amount. A variable valve operating device for an internal combustion engine, comprising: a solenoid that variably applies a pressing force to the pilot valve body in a seating direction so that the pilot valve body lifts. 2. The variable valve operating system for an internal combustion engine according to claim 1, wherein a lubricating hydraulic pressure generated by an oil pump of the internal combustion engine is used as the auxiliary hydraulic pressure. 3. The variable valve operating system for an internal combustion engine according to claim 1, wherein a control pressure obtained by further adjusting a hydraulic pressure generated by an oil pump of the internal combustion engine is used as the auxiliary hydraulic pressure. 4. The on-off valve is provided in a hydraulic pressure introduction path to the auxiliary hydraulic chamber, and the auxiliary hydraulic chamber is closed when a predetermined engine speed or more is reached. Variable valve device for internal combustion engine. 5. An intake valve or an exhaust valve which is always biased in a closing direction by a valve spring, and a cam which is driven by a cam shaft and pressurizes working oil introduced from an oil pump through a check valve and an accumulator. Side plunger and valve side plunger that moves to one side by hydraulic oil pressurized by the cam side plunger to lift the intake valve or exhaust valve, and hydraulic oil pressurized by the cam side plunger is released to the accumulator In the variable valve operating system for an internal combustion engine, the release valve lifts from the main valve seat to release the hydraulic oil to the accumulator side, and pressurizes the pressurized hydraulic oil. In the state of sitting on the main valve seat against the pressure, the main valve body that shuts off the hydraulic oil from the accumulator side and the pressurized hydraulic oil The back pressure chamber, which is introduced via a valve, biases the main valve element in the seating direction by the hydraulic pressure of the introduced hydraulic oil, and the back pressure chamber is released to the accumulator side by lifting from the pilot valve seat. In the seated state, the back pressure chamber is shut off from the accumulator side, and the pilot valve body that receives the hydraulic pressure of the back pressure chamber in the lift direction and the hydraulic pressure of the back pressure chamber correspond to the desired lift amount. A solenoid that variably applies a pressing force to the pilot valve body in the seating direction so that the pilot valve body lifts when the hydraulic pressure is reached, and further, behind the accumulator. A variable valve operating system for an internal combustion engine, wherein an oil chamber is formed, and an on-off valve is provided to close the oil chamber when a predetermined engine speed or more is reached.