JPH0893425A - Variable valve system for internal combustion engine - Google Patents

Abstract

PURPOSE: To variably control the lift degree of a gas supply and exhaust valve without controlling current-carrying for every cycle and avoid making the lift property of the valve unstable due to the vibration of a pilot valve body. CONSTITUTION: A plunger 7 in the cam side iis driven by a cam shaft 10 to compress working oil in a main hydraulic chamber 9. A gas supply and exhaust valve 2 is pushed and opened by the hydraulic pressure of the main hydraulic chamber 9. A release valve 21 is put between the main hydraulic chamber 9 and an accumulator 11 and opened in the middle of lifting subsequently with a pilot valve body 35, so that the lift degree can variably be controlled. The pilot valve body 35 is lifted by the pressure of a back pressure chamber 29 and to stabilize the movement of the pilot valve body 35, a pilot orifice 49 and a check valve 50 are installed in parallel between a rear side oil chamber 41 and a front side oil chamber 42.

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 and the valve opening timing 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.

However, in the above-mentioned conventional variable valve operating system, since the energization stop timing has to be calculated and controlled for each cycle of each cylinder, the load is large in terms of the amount of calculation and the calculation speed of the microcomputer. There is a problem called. 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.

Therefore, the applicant of the present invention applies the pressing force to the pilot valve body so as to balance it with the hydraulic oil pressure, so that the release valve automatically operates due to a change in hydraulic pressure having a correlation with the lift amount. The variable valve device configured as described above was previously proposed (Japanese Patent Application Nos. 5-325687 and 5-25687).
331087).

FIG. 4 shows an example of the structure of the previously proposed variable valve operating device, which will be described below. In the figure, 1 is a cylinder head, 2 is an intake / exhaust valve, 3 is a valve spring, and a housing 4 of a lift control unit is superposed on the upper surface of the cylinder head 1 and formed on the lower surface of the housing 4. A valve side plunger 6 is slidably fitted in the cylinder hole 5. The valve side plunger 6 drives the intake / exhaust valve 2 to open and close.

A cam side plunger 7 is slidably arranged in a cylinder hole 8 on the upper surface of the housing 4. The cam side plunger 7 and the valve side plunger 6
And share the main hydraulic chamber 9 as a hydraulic chamber. That is, the cam side plunger 7 is the cam 1 of the cam shaft 10 that rotates in synchronization with the crankshaft (not shown) of the internal combustion engine.
0a is driven via the rocker arm 16, and the camshaft 10 rotates to reciprocate to pressurize the hydraulic oil in the main hydraulic chamber 9. The valve side plunger 6 is pressed by the hydraulic pressure in the lift direction of the intake / exhaust valve 2.

An accumulator 11 is provided in the main hydraulic chamber 9.
From the accumulator 1 via a hydraulic oil supply oil passage 14 provided with a check valve 12.
1 communicates with the discharge side of an oil pump (not shown) serving as a hydraulic oil supply source via a check valve 13 and a hydraulic pressure introduction hole 17.

Further, in order to variably control the lift amount of the intake / exhaust valve 2 in accordance with operating conditions and the like, a release valve 21 is arranged between the main hydraulic chamber 9 and the accumulator 11 on the low pressure side. That is, the hydraulic oil supply oil passage 1 including the check valve 12 is provided.
4, a main release oil passage 15 is provided in parallel with the main release oil passage 15, and a release valve 21 is provided in the main release oil passage 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 main releasing oil passage 15 between the main hydraulic chamber 9 and the accumulator 11, and has a bottomed cylindrical main valve body 25 in the cylinder 24. Is slidably fitted. The main valve body 25 shuts off between the main hydraulic chamber 9 and the accumulator 11 by seating the substantially conical tip portion on the main valve seat 26, and the main valve body 25 lifts. Then, the two are in communication. Specifically, a first oil chamber 27 is defined so as to face the tip of the main valve body 25, and a second oil chamber 28 is annularly formed via the main valve seat 26.
Is on the main hydraulic chamber 9 side, and the second oil chamber 28 is on the accumulator 11 side.
Side to side, respectively. A back pressure chamber 29 is defined between the main valve body 25 and the bottom of the cylinder 24 so as to face the first oil chamber 27. This back pressure chamber 29
It communicates with the first oil chamber 27 via an orifice 30 formed at the tip of the main valve body 25. That is, the hydraulic oil is introduced from the main hydraulic chamber 9 side through the orifice 30.

The main valve body 25 is lifted and seated mainly 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 faced. 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, each pressure receiving area has a relation 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.

The main valve body 25 is seated and the back pressure chamber 29 is
Is cut off against the low voltage side, P1 = P
It is 2.

On the other hand, the pilot valve mechanism 23 includes the back pressure chamber 2
When the pressure P2 in 9 reaches a pressure corresponding to a desired lift amount, the valve is automatically opened. That is, the pilot valve mechanism 23 has a needle-shaped pilot valve element 35 slidably supported, and in a state where the pilot valve element 35 is seated on the pilot valve seat 36, When the pilot release oil passage 34 is cut off and the pilot valve body 35 is lifted from the pilot valve seat 36, the two are communicated with each other to release the pressure.

The pilot valve body 35 receives a pressing force in the lift direction by the hydraulic pressure in the back pressure chamber 29 acting through the pilot valve seat 36. To counter this, the urging force of the pilot spring 37 and the solenoid are applied. 38
Is pressed in the seating direction by the magnetic force of. Here, the magnetic force of the solenoid 38 is given in proportion to the magnitude of the current.

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 a pressing force F3 = P2.S3. If the pressing force of the pilot spring 37 is F4 and the magnetic force of the solenoid 38 is F5,
The pilot valve element 35 is pressed in the seating direction by the pressing force (F4 + F5). Therefore, the pilot valve body 3
5 continues to sit down if F3 <(F4 + F5), then F3
When> (F4 + F5), the pilot valve seat 36 lifts.

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.

When the pressure P1 of the hydraulic oil in the main hydraulic chamber 9 rises due to the operation of the cam side plunger 7, the valve side plunger 6 moves forward and the intake / exhaust valve 2 lifts. In this case, if the engine speed is constant, the pressure P1 of the pressurized hydraulic oil and the lift amount of the intake / exhaust valve 2 have a correspondence relationship. Therefore, if the current of the solenoid 38 is controlled so that the pilot valve body 35 lifts when the pressure P1 of the pressurized hydraulic oil reaches the pressure corresponding to the desired lift amount, the pilot valve body 35 is lifted. As a result, the main valve body 25 opens (lifts), and the intake / exhaust valve 2 starts to move to the seating operation. That is, when the pilot valve body 35 is lifted, the pressure in the back pressure chamber 29 is drastically reduced, the main valve body 25 is lifted, the hydraulic pressure acting on the valve side plunger 6 is released to the accumulator 11, and intake and exhaust are performed. The valve 2 shifts to a sitting motion during the lift.

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. It

As described above, in the variable valve operating apparatus having the above-mentioned structure, the intake / exhaust valve 2 automatically starts the seating operation after being lifted by the desired amount, and the solenoid 38 is turned ON / OFF every cycle. No need to control. 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. Therefore, there is an advantage that the load of the calculation is reduced and requirements such as responsiveness are alleviated.

[0022]

In the example of FIG. 4 described above, the rear oil chamber 41 formed in the back portion of the pilot valve body 35.
And the pilot valve body 3 so as to face the rear oil chamber 41.
A front oil chamber 42 formed near the valve seat 36 of No. 5 communicates with each other through an oil passage 43 for communication. Furthermore, the oil passage 34 for pilot release and the oil passage 15 for main release are communicated with each other, and finally are communicated with the accumulator 11.

However, in such a structure, when the pilot valve body 35 is lifted, the pressure on the accumulator 11 side and hence the pressure on the rear oil chamber 41 side increases accordingly, and the pilot valve body 35 is urged in the seating direction. And Therefore, as shown in FIG. 5, the pilot valve mechanism 23
Swelling occurs at the opening of. This affects the opening degree of the main valve body 25 and causes the fluctuation of the hydraulic pressure in the main hydraulic chamber 9, so that the lift characteristic of the intake / exhaust valve 2 is accompanied by undulation as shown in the figure. This phenomenon causes variations in combustion among cylinders.

If the rear oil chamber 41 at the back of the pilot valve body 35 is simply opened to the atmosphere, such a problem will not occur, but in this case, the operating oil, which is one of the causes of deterioration of fuel consumption, is discharged to the outside. Pilot valve body 3 in order to suppress the leakage of
It is necessary to set the fitting gap of No. 5 to be extremely small, and as a result, the responsiveness of the pilot valve body 35 is deteriorated, so such a configuration cannot be adopted.

In the example of FIG. 4 described above, the return of the hydraulic oil from the accumulator 11 to the main hydraulic chamber 9 after the end of the cam lift is performed via the hydraulic oil supply oil passage 14 having the check valve 12. There is. In this case, it is necessary to increase the size of the check valve 12 in order to suppress energy loss (deterioration of fuel consumption) due to pressure loss, and if the size of the entire device is reduced, the layout becomes difficult. is there.

[0026]

In order to solve the former problem, a variable valve operating system for an internal combustion engine according to a first aspect of the present invention includes an intake valve or an exhaust valve which is constantly urged in a closing direction by a valve spring, Driven by the camshaft, the cam side plunger that pressurizes the hydraulic oil in the hydraulic chamber, and the hydraulic oil pressurized by the cam side plunger actuate to one side,
A valve-side plunger that lifts the intake valve or the exhaust valve, an accumulator, a check valve interposed between the accumulator and the hydraulic chamber, and a pressure in the hydraulic chamber that is pressurized by the cam-side plunger. In the lift direction and releases the pressure of the hydraulic chamber to the accumulator side at the time of lifting, the hydraulic oil in the hydraulic chamber is introduced through the orifice, and the main valve is actuated by the pressure of the introduced hydraulic oil. The back pressure chamber that urges the body in the seating direction, the pilot valve body that receives the pressure in the back pressure chamber in the lift direction and opens and closes between the back pressure chamber and the accumulator side, and the pressure in the hydraulic chamber are desired. A solenoid that variably applies a pressing force toward the seating direction to the pilot valve body so that the pilot valve body lifts when the pressure corresponding to the valve lift amount is reached. A release valve having an id, and a pilot orifice communicating with a rear oil chamber formed at the back of the pilot valve body and a front oil chamber formed near the valve seat of the pilot valve body so as to face the rear oil chamber, A check valve that is provided in parallel with the pilot orifice and that allows the flow of hydraulic oil from the rear oil chamber to the front oil chamber and that blocks the flow from the front oil chamber to the rear oil chamber; The rear oil chamber is provided with an oil passage communicating with the pilot release oil passage on the pilot valve mechanism outlet side to the accumulator.

In order to solve the former problem as well as the latter problem, the variable valve operating device according to the second aspect uses an intake valve or an exhaust valve which is always biased in the closing direction by a valve spring, and a camshaft. A cam side plunger that is driven and pressurizes the hydraulic oil in the hydraulic chamber, a valve side plunger that operates to one side by the hydraulic oil pressurized by the cam side plunger and lifts the intake valve or the exhaust valve, and an accumulator, A main valve body that receives the pressure of the hydraulic chamber pressurized by the cam side plunger in the lift direction, and releases the pressure of the hydraulic chamber to the accumulator side via the annular oil chamber during lifting, the hydraulic oil of the hydraulic chamber. Is introduced through the orifice, and the pressure of the introduced hydraulic oil urges the main valve element in the seating direction. Pilot valve body that receives in the direction of the arrow and opens and closes between the back pressure chamber and the accumulator side, and the pilot valve body lifts when the pressure in the hydraulic chamber reaches a pressure corresponding to a desired valve lift amount. As described above, a release valve having a solenoid that variably applies a pressing force toward the seating direction with respect to the pilot valve body,
A pilot orifice that communicates with a rear oil chamber formed in the back of the pilot valve body and a front oil chamber formed near the valve seat of the pilot valve body so as to face the rear oil chamber,
A check valve that is provided in parallel with the pilot orifice and that allows the flow of hydraulic oil from the rear oil chamber to the front oil chamber and that blocks the flow from the front oil chamber to the rear oil chamber; The oil chamber, an oil passage communicating with the pilot release oil passage on the pilot valve mechanism outlet side leading to the accumulator, and interposed between the pilot release oil passage on the pilot valve mechanism outlet side and the accumulator, and A check valve that blocks the flow of hydraulic oil from the accumulator to the pilot release oil passage, and the pressure in the annular oil chamber surrounding the main valve element acts on the closed main valve element in the lift direction. As described above, the main valve body is provided with a pressure receiving portion.

Further, in the invention of claim 3, the pilot orifice is arranged outside the pilot valve body.

In the invention of claim 4, the pilot orifice is arranged inside the pilot valve body.

According to the invention of claim 5, the check valve between the front oil chamber and the rear oil chamber is arranged outside the pilot valve body.

In the invention of claim 6, the check valve between the front oil chamber and the rear oil chamber is arranged inside the pilot valve body.

[0032]

In the structure of claim 1 or 2, when the cam side plunger is pressed by the cam shaft, the hydraulic pressure in the hydraulic chamber increases, and the valve side plunger moves accordingly. That is, the intake / exhaust valve is lifted in a form corresponding to the hydraulic pressure. When the hydraulic pressure in this hydraulic chamber increases, the pressure in the back pressure chamber also increases. When the pressing force on the pilot valve body variably set by the solenoid exceeds the pressing force by the hydraulic pressure in the back pressure chamber, the pilot valve body lifts and releases the back pressure chamber to the low pressure accumulator side. Along with this,
The main valve body is also lifted to release the pressure in the hydraulic chamber to the accumulator side. 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.

Here, when the pilot valve body is lifted, the working oil in the rear oil chamber smoothly moves to the front oil chamber via the check valve, and the pilot valve body is smoothly moved in the lifting direction. Secure operation. On the other hand, when the hydraulic oil tries to move from the front oil chamber to the rear oil chamber, the check valve closes and only a small amount of hydraulic oil can move through the pilot orifice. Therefore, when the pilot valve body is lifted, the pressure on the accumulator side increases, and when the pilot valve body is pushed in the seating direction, the movement of the pilot valve body is blocked. That is, the lift of the pilot valve body becomes stable. When the cam lift ends and the pressure in the back pressure chamber decreases, the pilot valve body returns to the seated position as the hydraulic oil moves through the pilot orifice.

According to the second aspect of the invention, after the cam lift is completed, the hydraulic oil returns from the accumulator via the main valve body. In other words, when the cam lift ends and the pressures in the hydraulic chamber and the back pressure chamber drop, the accumulator side and the pilot release oil passage are shut off by a check valve.
A pressure difference is generated between the back pressure chamber and the annular oil chamber communicating with the accumulator. This pressure difference acts on the pressure receiving portion of the main valve body, and the main valve body lifts. As a result, the hydraulic oil returns from the accumulator to the oil chamber.

In the third aspect of the invention, the front oil chamber and the rear oil chamber communicate with each other through the pilot orifice arranged outside the pilot valve body.

According to the fourth aspect of the invention, the front oil chamber and the rear oil chamber communicate with each other through the internal passage of the pilot valve body having the pilot orifice.

According to the fifth aspect of the invention, the check valve is arranged outside the pilot valve body, and the movement of the working oil is allowed only in the direction from the rear oil chamber to the front oil chamber via the check valve. It

Further, in the structure of claim 6, the check valve is arranged inside the pilot valve body, and is operated only in the direction from the rear oil chamber to the front oil chamber via the internal passage provided with the check valve. Oil movement is allowed.

[0039]

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 a main part of an internal combustion engine showing a first embodiment of the present invention. This embodiment is based on FIG.
It has the same basic structure as that of FIG. 4, and the same parts as those in FIG.

Reference numeral 1 denotes a cylinder head arranged on an upper portion of a cylinder block (not shown).
An intake / exhaust valve 2 is slidably mounted on the. The intake / exhaust valve 2 is constantly urged in the closing direction by a valve spring 3. On the upper surface of the cylinder head 1, a housing 4 of the lift control unit is arranged so as to overlap,
A valve side plunger 6 is slidably fitted in a cylinder hole 5 formed in the lower surface 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.

On the upper surface of the housing 4, a cam side plunger 7 is slidably arranged in a cylinder hole 8. The cam side plunger 7 and the valve side plunger 6
And share the main hydraulic chamber 9 as a hydraulic chamber. That is, the cam side plunger 7 is the cam 1 of the cam shaft 10 that rotates in synchronization with the crankshaft (not shown) of the internal combustion engine.
0a is driven via the rocker arm 16, and the camshaft 10 rotates to reciprocate to pressurize the hydraulic oil in the main hydraulic chamber 9. The valve side plunger 6 is pressed by the hydraulic pressure in the lift direction of the intake / exhaust valve 2.

An accumulator 11 is provided in the main hydraulic chamber 9.
From the accumulator 1 via a hydraulic oil supply oil passage 14 provided with a check valve 12.
1 communicates with the discharge side of an oil pump (not shown) serving as a hydraulic oil supply source via a check valve 13 and a hydraulic pressure introduction hole 17. The accumulator 11 is composed of an accumulator piston 11a and an accumulator spring 11b. It should be noted that this hydraulic system is integrated with the engine lubricating system, and the engine lubricating oil is used as the working oil and the oil pump for lubrication that is mechanically driven by the engine output is also used as it is. That is, when the cam 10 a is not lifted, the hydraulic oil is sent back from the accumulator 11 into the main hydraulic chamber 9 via the check valve 12, and the shortage is supplied via the check valve 13 to the lubricating oil pump. Will be replenished at.

Further, in order to variably control the lift amount of the intake / exhaust valve 2 according to the operating conditions, etc., a release valve 21 is arranged between the main hydraulic chamber 9 and the accumulator 11 on the low pressure side. That is, the hydraulic oil supply oil passage 1 including the check valve 12 is provided.
4, a main release oil passage 15 is provided in parallel with the main release oil passage 15, and a release valve 21 is provided in the main release oil passage 15.
The release valve 21 includes a main valve mechanism 22 and a pilot valve mechanism 23 inside a valve housing 21a.

The main valve mechanism 22 is for directly opening and closing the main release oil passage 15 between the main hydraulic chamber 9 and the accumulator 11, and has a bottomed cylindrical main valve body 25 in the cylinder 24. Is slidably fitted. The main valve body 25 shuts off between the main hydraulic chamber 9 and the accumulator 11 by seating the substantially conical tip portion on the main valve seat 26, and the main valve body 25 lifts. Then, the two are in communication. Specifically, the first oil chamber 27 is defined so as to face the tip of the main valve body 25, and the second oil chamber 28 is annularly formed via the main valve seat 26. The second oil chamber 2 in which the first oil chamber 27 is the main oil pressure chamber 9 side and the annular oil chamber through the upstream side portion and the downstream side portion
8 communicates with the accumulator 11 side, respectively.
A back pressure chamber 29 is defined between the main valve body 25 and the bottom of the cylinder 24 so as to face the first oil chamber 27. 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 hydraulic oil is introduced from the main hydraulic chamber 9 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 faced. 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, each pressure receiving area has a relation 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.

The main valve body 25 is seated and the back pressure chamber 29 is
Is cut off against the low voltage side, P1 = P
It is 2.

On the other hand, as described with reference to FIG. 4, the pilot valve mechanism 23 automatically opens when the pressure P2 in the back pressure chamber 29 reaches a pressure corresponding to a desired lift amount. Has become. That is, this pilot valve mechanism 2
3 has a needle-shaped pilot valve body 35 slidably supported, and in a state where the pilot valve body 35 is seated on the pilot valve seat 36, the back pressure chamber 29 and the pilot release oil passage 34 are provided. And the pilot valve 3
When 5 is lifted from the pilot valve seat 36, the two communicate with each other and the pressure is released. The pilot valve element 35 is slidably fitted to the center of the valve housing 21a and has a small diameter portion 35a on the front end side for opening and closing the pilot valve seat 36 and a large diameter portion 35b on the base end side. are doing.

The pilot valve body 35 receives a pressing force in the lift direction due to the hydraulic pressure in the back pressure chamber 29 acting through the pilot valve seat 36. To counter this, the urging force of the pilot spring 37 and the solenoid are applied. 38
Is pressed in the seating direction by the magnetic force of. As described above, the magnetic force of the solenoid 38 is given in proportion to the magnitude of its current.

By fitting the large diameter portion 35b of the pilot valve body 35 into the cylinder portion 45 of the valve housing 21a, a rear oil chamber 41 accommodating the pilot spring 37 is defined at the back of the pilot valve body 35. Further, a front oil chamber 42 is defined in an annular shape surrounding the small diameter portion 35a near the pilot valve seat 36 so as to be opposed thereto. The rear oil chamber 41 communicates with the pilot release oil passage 34 on the outlet side of the pilot valve seat 36 and the accumulator 11 via an oil passage 46 formed in the valve housing 21a. In addition, the rear oil chamber 41 and the front oil chamber 4
Two communication paths 47, 48 are provided in parallel with each other between the two. In this embodiment, these communication passages 4
7, 48 are formed inside the valve housing 21 a which is outside the pilot valve body 35. One communication passage 47
Are relatively thin, and a pilot orifice 49 having a predetermined passage cross-sectional area is interposed therein. Further, the other communication passage 48 is formed relatively thick, and a check valve 50 using a spherical valve body and a spring is interposed therein. This check valve 50
The hydraulic oil is allowed to move from the rear oil chamber 41 to the front oil chamber 42, and the reverse movement from the front oil chamber 42 to the rear oil chamber 41 is prevented. The opening pressure of the check valve 50 is set as small as possible in order to reduce the pressure loss when the hydraulic oil flows, and the opening thereof can be secured large.

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

Let S3 be the pressure receiving area for the hydraulic oil of the pilot valve element 35 when seated.
5 is pressed in the lift direction with a pressing force F3 = P2 · S3. In addition, the pressing force of the pilot spring 37 is F
4. If the magnetic force of the solenoid 38 is F5, the pilot valve body 35 is pressed in the seating direction by the pressing force (F4 + F5). Therefore, the pilot valve body 35 is F3
If <(F4 + F5), continue sitting, F3> (F4 +
When it becomes F5), the pilot valve seat 36 lifts.

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.

When the pressure P1 of the hydraulic oil in the main hydraulic chamber 9 rises due to the operation of the cam side plunger 7, the valve side plunger 6 moves forward and the intake / exhaust valve 2 lifts. In this case, if the engine speed is constant, the pressure P1 of the pressurized hydraulic oil and the lift amount of the intake / exhaust valve 2 have a correspondence relationship. Therefore, if the current of the solenoid 38 is controlled so that the pilot valve body 35 lifts when the pressure P1 of the pressurized hydraulic oil reaches the pressure corresponding to the desired lift amount, the pilot valve body 35 is lifted. As a result, the main valve body 25 opens (lifts), and the intake / exhaust valve 2 starts to move to the seating operation. That is, when the pilot valve body 35 is lifted, the pressure in the back pressure chamber 29 is drastically reduced, the main valve body 25 is lifted, the hydraulic pressure acting on the valve side plunger 6 is released to the accumulator 11, and intake and exhaust are performed. The valve 2 shifts to a sitting motion during the lift.

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 engine speed and load of the internal combustion engine. It

Therefore, in the variable valve operating device having the above-mentioned structure, the intake / exhaust valve 2 automatically starts the seating operation after being lifted by the desired amount, and the solenoid 38 is controlled to be turned ON / OFF every 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. Therefore, the load of the calculation is reduced, and the requirements such as responsiveness are reduced.

When the pilot valve body 35 is lifted as described above, the working oil in the rear oil chamber 41 is transferred to the communication passage 4
The check valve 50 of No. 8 is pushed open to move quickly to the front oil chamber 42. Therefore, the pressure in these oil chambers 41 and 42 does not hinder the movement of the pilot valve body 35, and the pilot valve body 35 lifts smoothly.

On the other hand, when the pilot valve body 35 is lifted, the pressure on the accumulator 11 side, and thus the rear oil chamber 41, is increased.
Pressure rises, and a force for urging the pilot valve element 35 in the seating direction is generated. In this case, the check valve 50 causes the flow of the hydraulic oil from the front oil chamber 42 to the rear oil chamber 41. Since it is blocked, the movement of the pilot valve body 35 is restricted. Therefore, the waviness of the opening degree of the pilot valve element 35 as in the prior art is eliminated, and stable operation can be secured. That is, the change in the opening degree of the main valve body 25 does not change, and the seating operation of the intake / exhaust valve 2 becomes stable. Further, when the cam lift ends and the pressure on the back pressure chamber 29 side decreases, the front oil chamber 42 to the rear oil chamber 4 via the pilot orifice 49.
The hydraulic oil gradually moves to 1, and the pilot valve body 35 is gently seated. The passage area of the pilot orifice 49 is set so that the operation of the pilot valve body 35 in the seating direction can be sufficiently dampened and the pilot valve body 35 is closed during one rotation of the cam 10a.

Further, the operating oil leaking from the back pressure chamber 29 side to the rear oil chamber 41 through the periphery of the pilot valve body 35 is all recovered to the accumulator 11 side through the oil passage 46. Therefore, leakage to the outside, which causes deterioration of fuel efficiency, is prevented. In addition, from this, the pilot valve body 3
It is not necessary to make the fitting gap around the circumference 5 so small, and it is possible to obtain sufficiently high responsiveness at the time of lift to the pressure change of the main hydraulic chamber 9.

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the pilot valve body 35
Two communicating passages 47 and 48 are formed inside the large diameter portion 35b along the longitudinal direction. Then, as in the above-described embodiment, a pilot orifice 49 and a check valve 50 are provided in each of the communication passages 47 and 48. Therefore, according to this embodiment, the valve housing 21 of the release valve 21 is
The size of a can be reduced.

Although not shown, it is possible to form the pilot orifice inside the valve body of the check valve provided outside or inside the pilot valve body 35.

Next, FIG. 3 shows a third embodiment corresponding to claim 2. In this embodiment, as apparent from comparison with FIG. 1, the hydraulic oil supply oil passage 14 is not provided between the accumulator 11 and the main hydraulic chamber 9.
That is, the hydraulic pressure introduction hole 1 connected to an oil pump (not shown)
7 and the accumulator 11 communicate with the second oil chamber 28 around the main valve body 25 via the main releasing oil passage 15, and via the oil passage 46 inside the valve housing 21a, the rear oil chamber 41 and It communicates with the pilot release oil passage 34, but does not directly communicate with the main hydraulic chamber 9.
A check valve 51 is interposed between the oil passage 46, particularly between the pilot release oil passage 34 and the main release oil passage 15 of the oil passage 46. The check valve 51 is configured to allow a flow from the pilot release oil passage 34 side to the accumulator 11 side and block a flow from the accumulator 11 side to the pilot release oil passage 34 side.

The outer peripheral portion of the front end surface of the main valve body 25 with respect to the main valve seat 26 is exposed in the second oil chamber 28 as a pressure receiving portion 25a. The pressure receiving portion 25a controls the pressure in the second oil chamber 28 when the main valve body 25 is closed.
Of the main valve spring 31. The pressure receiving area is set according to the pressure accumulated in the accumulator 11 and the spring force of the main valve spring 31.

In this configuration, when the cam lift ends and the pressure in the main hydraulic chamber 9 decreases, and a pressure difference occurs with the pressure in the accumulator 11, a back pressure equal to the pressure in the main hydraulic chamber 9 is generated. A pressure difference is generated between the chamber 29 and the second oil chamber 28, and a force in the lift direction acts on the pressure receiving portion 25a of the main valve body 25. Therefore, the main valve body 25 lifts and the main release oil passage 1
5 from the accumulator 11 side to the main hydraulic chamber 9
Hydraulic fluid returns to. Here, the flow passage area secured between the main valve body 25 and the main valve seat 26 is larger than that of a normal check valve, which is advantageous in terms of pressure loss. If the check valve 51 is not provided, the pressure in the back pressure chamber 29 also increases via the pilot valve mechanism 23, so that the pressure difference acting on the main valve body 25 becomes small and it is difficult to lift it. Becomes Further, the check valve 51 may be smaller than the check valve 12 of the first embodiment because the flow rate of the hydraulic oil flowing therethrough is small.

As described above, in the third embodiment, the hydraulic oil supply oil passage 14 and the check valve 12 in the passage can be eliminated, the size and simplification of the device can be achieved, and the hydraulic oil return with a large flow rate can be achieved. The pressure loss at the time can be reduced.

[0068]

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. By interposing a pilot orifice and a check valve between the front and rear oil chambers of the pilot valve element, it is possible to stabilize the behavior of the pilot valve element that operates automatically with hydraulic pressure, and to prevent vibration of the pilot valve element. It is possible to prevent the lift characteristics of the intake / exhaust valve from being destabilized. Moreover, at the same time, the leakage of hydraulic oil to the outside can be avoided, and the responsiveness of the pilot valve body is also excellent.

According to the second aspect of the present invention, the check valve in the hydraulic oil supply oil passage and its passage can be eliminated, the size and simplification of the device can be achieved, and the pressure when returning the hydraulic oil with a large flow rate can be achieved. The loss can be reduced.

If the pilot orifice and the check valve are provided outside the pilot valve body as in claim 3 or 5, the diameter of the pilot orifice and the size of the check valve can be freely set. In addition, the pilot valve body is not made large.

If the pilot orifice and the check valve are provided inside the pilot valve body as in claim 4 or claim 6, the housing of the release valve can be downsized.

[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 a sectional view showing a second embodiment of the variable valve operating device according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the variable valve operating device according to the present invention.

FIG. 4 is a cross-sectional view showing a configuration example of the previously proposed variable valve operating device.

5 is a characteristic diagram for explaining vibration of the pilot valve body and the like in the configuration of FIG.

[Explanation of symbols]

 2 ... Intake / exhaust valve 3 ... Valve spring 6 ... Valve side plunger 7 ... Cam side plunger 9 ... Main hydraulic chamber 11 ... Accumulator 21 ... Release valve 23 ... Pilot valve mechanism 25 ... Main valve body 25a ... Pressure receiving portion 28 ... Second oil Chamber (annular oil chamber) 29 ... Back pressure chamber 30 ... Orifice 35 ... Pilot valve body 41 ... Rear oil chamber 42 ... Front oil chamber 46 ... Oil passage 49 ... Pilot orifice 50 ... Check valve 51 ... Check valve

Front Page Continuation (72) Inventor Yuji Sato 3-13-26, Yasuyukicho, Higashimatsuyama City, Saitama Prefecture XXCELL Higashi-Matsuyama Factory (72) Inventor Hirohito Tokubuki 3--1326, Yasuyuki Town, Higashimatsuyama City, Saitama Prefecture No. Incorporated company XXEL Higashimatsuyama factory (72) Inventor Hiroshi Kanai 3-13-26, Yasumicho, Higashimatsuyama City, Saitama Prefecture XXEL Higashimatsuyama factory

Claims (6)

[Claims] 1. An intake valve or an exhaust valve which is always biased 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 a cam side plunger. Valve side plunger that moves to one side by the hydraulic oil that lifts the intake valve or the exhaust valve, an accumulator, a check valve interposed between the accumulator and the hydraulic chamber, and the cam side plunger. The main valve body that receives the pressure of the pressurized hydraulic chamber in the lift direction and releases the pressure of the hydraulic chamber to the accumulator side at the time of lifting, the working oil of the hydraulic chamber is introduced through the orifice, and this is introduced. Back pressure chamber that urges the main valve body in the seating direction by the pressure of the hydraulic oil, receives the pressure of this back pressure chamber in the lift direction, and The pilot valve body that opens and closes between the pilot valve body and the hydraulic valve, and the pilot valve body is lifted when the pressure in the hydraulic chamber reaches a pressure corresponding to a desired valve lift amount. A release valve having a solenoid that variably applies a pressing force toward the seating direction, a rear oil chamber generated at the back of the pilot valve body, and a valve seat near the pilot valve body so as to face the rear oil chamber. A pilot orifice that connects the generated front oil chamber to each other, and a pilot orifice that is provided in parallel with this pilot orifice and that allows the flow of hydraulic oil from the rear oil chamber to the front oil chamber, and at the same time from the front oil chamber to the rear oil chamber. Internal combustion engine comprising a check valve for blocking flow to the chamber, and an oil passage communicating the rear oil chamber with a pilot release oil passage on the pilot valve mechanism outlet side leading to the accumulator. Variable valve system of the function. 2. 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 a cam side plunger. Is operated by the working oil to lift the intake valve or exhaust valve, and receives the pressure in the hydraulic chamber pressurized by the valve-side plunger, accumulator, and cam-side plunger in the lift direction. The main valve body that releases the pressure in the chamber to the accumulator side via the annular oil chamber, the hydraulic oil in the hydraulic chamber is introduced through the orifice, and the main valve body is seated in the seating direction by the pressure of the introduced hydraulic oil. A back pressure chamber that urges the back pressure chamber, a pilot valve element that receives the pressure of the back pressure chamber in the lift direction and that opens and closes between the back pressure chamber and the accumulator side, And the pressing force is variably applied to the pilot valve body in the seating direction so that the pilot valve body lifts when the pressure in the hydraulic chamber reaches a pressure corresponding to a desired valve lift amount. A release valve having a solenoid; and a pilot orifice for communicating a rear oil chamber formed at the back of the pilot valve body and a front oil chamber formed near the valve seat of the pilot valve body so as to face the rear oil chamber with each other. A check valve that is provided in parallel with the pilot orifice and that allows the flow of hydraulic oil from the rear oil chamber to the front oil chamber and that blocks the flow from the front oil chamber to the rear oil chamber; An oil passage that communicates the rear oil chamber with a pilot release oil passage on the pilot valve mechanism outlet side that leads to the accumulator, a pilot release oil passage on the pilot valve mechanism outlet side, and the accumulator. A check valve that is interposed between the accumulator and blocks the flow of hydraulic oil from the accumulator to the pilot release oil passage, and closes the pressure in the annular oil chamber that surrounds the main valve body. A variable valve operating device for an internal combustion engine, wherein a pressure receiving portion is provided on the main valve body so as to act on the main valve body in a lifted state. 3. The variable valve operating system for an internal combustion engine according to claim 1, wherein the pilot orifice is arranged outside a pilot valve body. 4. The variable valve operating system for an internal combustion engine according to claim 1, wherein the pilot orifice is arranged inside a pilot valve body. 5. The variable operation of the internal combustion engine according to claim 1, wherein the check valve between the front oil chamber and the rear oil chamber is arranged outside the pilot valve body. Valve device. 6. The variable operation of the internal combustion engine according to claim 1, wherein the check valve between the front oil chamber and the rear oil chamber is arranged inside a pilot valve body. Valve device.