JPH02223612A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To make the rising operation of an engine vale smooth by holding a spherical valve body with a retainer secured on a valve driving piston so that a damper chamber opening can be opened and closed, so as to decrease the opening pressure of a check valve. CONSTITUTION:When the oil pressure from a oil pressure generating means 10 works upon a valve hole 39 under the fully closed condition of an engine valve 5, a valve body 41 is raised up by oil pressure, so that a check valve 38 opens and the oil pressure from the oil pressure generating means 10 works upon a damper chamber 28, and a valve driving piston 29 operates in the opening direction of the engine valve 5. When the engine valve 5 operates from a fully close condition to a given open condition, the communication of the valve hole 39 with the oil pressure generating means 10 is shut down, and the force in the direction where the valve body 41 is made to seat itself on a valve seat 40 becomes larger to close the check valve 38. Since the check valve 38 can be opened in this way even if the oil pressure of the valve hole 39 is relatively low when the engine valve 5 is fully closed, the valve is opened immediately when the oil pressure from the oil generating means 10 work upon it. It is thus possible to make valve opening action smooth.

Description

Detailed Description of the Invention A3 Object of the Invention (+) Industrial Field of Application The present invention is directed to a valve driving piston whose one end is interlocked and connected to an engine valve that is spring-biased in the valve-closing direction, and which slides on a cylinder body. A hydraulic pressure generating means is provided between a damper chamber which is movably fitted and defined between the cylinder body and the valve driving piston, and a hydraulic pressure generating means which generates hydraulic pressure in response to the opening timing of the engine valve. The present invention relates to a valve operating system for an internal combustion engine in which a check valve that only allows flow of hydraulic oil from the damper chamber to the damper chamber is provided.

(2) Prior Art Conventionally, such devices have been developed, for example, in Japanese Patent Publication No. 52-35813
It is publicly known from the publication No.

(3) Problems to be Solved by the Invention In this device, when the engine valve is closed, hydraulic oil from the hydraulic pressure generating means is introduced into the damper chamber via the check valve, and the valve is driven by the hydraulic pressure in the damper chamber. The piston is driven in the engine valve opening direction, but in the conventional check valve described above, a valve body biased by a spring in the valve closing direction is disposed on the valve driving piston, and the engine valve opens. During operation, hydraulic pressure is required to overcome the spring force and open the valve, and the startup of the engine valve opening operation cannot be said to be smooth.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a valve operating system for an internal combustion engine in which the engine valve opening operation starts smoothly by lowering the valve opening operation pressure of the check valve. do.

B9 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the check valve is a valve provided on the valve driving piston to communicate with the hydraulic pressure generating means from the fully closed state of the engine valve to the predetermined valve open state. a hole, a valve seat provided at the opening edge of the cough valve hole to the damper chamber, a spherical valve body that can be seated on the valve seat and stored in the damper chamber, and the valve body can be opened and closed in a free state. and a retainer fixed to the valve drive piston to maintain the valve drive piston.

(2) Effect According to the above configuration, when the oil pressure from the oil pressure generating means acts on the valve hole when the engine valve is fully open, the oil pressure causes the valve body to hold L.
The check valve opens, and the hydraulic pressure from the hydraulic pressure generating means acts on the damper chamber, and the valve driving piston operates in the direction of opening the engine valve. Furthermore, when the engine valve operates from a fully closed state to a predetermined valve open state, communication between the valve hole and the hydraulic pressure generating means is cut off, and as a result, the force in the direction of seating the valve body on the valve seat increases, causing the check valve to close. Close the valve.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. An intake valve 5 as an engine valve is provided with an intake valve port 2 that is open to the intake boat 3 and is bored to communicate with the intake boat 3.
is guided so as to be vertically movable by a guide tube 6 provided in the cylinder head I-1 to open and close the intake valve port 2.

Moreover, the flange 5a provided at the upper end of the intake valve 5 and the cylinder head! ] A valve spring 7 is installed between the
The spring force of the valve spring 7 biases the intake valve 5 upward, that is, in the valve closing direction G.

On the other hand, a camshaft 8 rotatably driven by a crankshaft (not shown) is disposed above the cylinder head H, and a hydraulic pressure generating means 10 including a cam 9 provided on the camshaft 8 is connected to the cam 9. It is disposed above the intake valve 5 to generate hydraulic pressure to open and close the intake valve 5 according to the profile.

In FIG. 2, the hydraulic pressure generating means 10 includes the cam 9,
A cylinder body 12 is fixed to a fixed support part 11 provided on the cylinder head H, and a lifter 13 is in sliding contact with the cam 9 and is slidably fitted to the upper part of the support part 11.
and a cam driven piston 14 which is slidably fitted into the upper part of the cylinder body 12 with its upper end abutting the lifter 13.

Above the intake valve 5, the support part 11 has a first
The hole 15 has a smaller diameter than the first hole 15 and is connected to the lower end of the first hole 15 via the step 16, and the second hole 17 has a larger diameter than the second hole 17 and is stepped. A third hole 19 is connected to the lower end of the second hole 17 via the portion 18 and extends vertically coaxially with the intake valve 5 .

The lifter 13 is formed into a cylindrical shape with a bottom so that its closed end outer surface is in sliding contact with the cam 9, and is slidably fitted into the first hole 15. A contact protrusion 13 a that abuts the upper end of the cam driven piston 14 projects from the center of the inner surface of the closed end of the dust lid 13 .

The cylinder body 12 has a small diameter portion 12a large enough to be inserted into the second hole 17 and a large diameter portion 12b large enough to fit into the third hole 19 coaxially through an upwardly facing stepped portion 12c. They are arranged in a row and basically formed into a cylindrical shape. The large diameter portion 12b of the cylinder body 12 is inserted into the third hole by inserting the small diameter portion 12a into the second hole 17 with a shim 20 interposed between the step portion 12c and the step portion 18. 19 is fitted.

Moreover, a male thread 21 is carved in a portion of the small diameter portion 12a that protrudes upward from the second hole portion 17.
The cylinder body 12 is fixed to the support part 11 by tightening the nut 22 which is screwed into the cylinder body 1 until it abuts against the stepped part 16. Further, an annular seal member 23 is fitted onto the outer surface of the large diameter portion 12b of the cylinder body 12 to achieve a seal between the large diameter portion 12b and the inner surface of the third hole portion 19.

A partition wall 26 that partitions the inside of the cylinder body 12 into a lower cylinder hole 24 and a north cylinder hole 25 is provided in the middle of the cylinder body 12, and the cam driven piston 14 is connected to the partition wall 26. A hydraulic oil chamber 27 is defined therebetween, and the upper cylinder hole 25 is slidably fitted. Also, the intake valve 5
The valve driving piston 29 that comes into contact with the upper end of the partition wall 26
A damper chamber 2 is defined between the lower cylinder hole 24 and the lower cylinder hole 24.
is slidably fitted to.

An annular recess 3 is provided in the axially intermediate portion of the lower cylinder hole 24.
1h<a, and an oil passage 32 communicating the hydraulic oil chamber 27 and the annular recess 31 is bored in the cylinder body 12.

Referring also to FIG. 3, a bottomed hole 33 is coaxially provided at one end of the valve drive piston 29 on the damper chamber 28 side so that a part of the peripheral wall becomes a thin-walled portion 29a. The portion 29a is provided with a fixed orifice 34 that constantly communicates the damper chamber 28 with the annular recess 31, and a notch 35 above the fixed orifice 34. A variable orifice 36 is configured.

Furthermore, the variable orifice 36 is configured such that the opening area becomes 0 just before the intake valve 5 is seated, that is, the upper edge of the annular recess 31 is located between the fixed orifice 34 and the notch 35 when the intake valve 5 is seated. is set to

The valve drive piston 29 is connected to the damper chamber 2 from the hydraulic oil chamber 27.
A check valve 38 is provided that allows hydraulic oil to flow only to the valve 8. The -y nick valve 38 constantly communicates with the annular recess 31 until the intake valve 5 is opened by a predetermined amount from the fully closed state, and is connected to the valve drive piston 29 to open at the closed end of the bottomed hole 33. The valve hole 39 to be drilled and the valve hole 3
9, a spherical valve seat 40 formed in a spherical shape at the opening edge on the damper chamber 28 side, a spherical valve body 41 that can be seated on the valve seat 40 and stored in the damper chamber 28; A cap-shaped retainer 42 is fixed to the valve drive piston 29 so that the valve drive piston 29 can be opened and closed. The retainer 42 is large enough to be accommodated in the bottomed hole 33,
It is held between the closed end of the bottomed hole 33 in the valve drive piston 29 and a retaining ring 43 fitted to the inner surface of the bottomed hole 33 .

This retainer 42 has 1 part inside the retainer 42 and 2 parts in the damper chamber 2.
A plurality of communication holes 44 are bored to communicate with 8.

In this check valve 38, the valve body 41 is moved by the hydraulic pressure in the damper chamber 28, that is, the retainer 42, and the self-weight of the valve body 41.
The force pushing down the valve body 41 is caused by the hydraulic pressure inside the valve hole 39.
When the force pushing upward is applied twice, the valve body 41 seats on the valve seat 40 and the valve closes.

Next, to explain the operation of this embodiment, when the intake valve 5 is fully closed, the hydraulic pressure generating means 1<) is in the state shown in FIG. 2, and from this state shown in FIG. The lifter 13 is pushed down by the cam 9. As a result, the cam driven piston 14 is pushed downward, the volume of the hydraulic oil chamber 27 is contracted, and the hydraulic oil in the hydraulic oil chamber 27 is guided to the annular recess 31 via the oil passage 32, and further passes through the fixed orifice 34. After that, it is introduced into the damper chamber 2B.

At this time, the damper chamber 2
A downward force due to the hydraulic pressure of 8 and its own weight, and an upward force due to the hydraulic pressure introduced into the valve hole 39 are acting.
When the upward force becomes larger than the downward force, the valve body 41 separates from the valve seat 40 and the hydraulic oil in the hydraulic oil chamber 27 is introduced into the damper chamber 28 via the check valve 38.

Therefore, the oil pressure in the damper chamber 28 increases, and the valve drive piston 29 is pushed downward.

During the downward sliding of this valve drive screw 29, the oil passage 32
directly communicates with the damper chamber 28 via the annular recess 31, the amount of hydraulic pressure flowing into the damper chamber 28 becomes even larger, and the valve driving piston 29 is further pushed down. As a result, the intake valve 5 is driven to open against the spring force of the valve spring 7.

During the opening operation of the intake valve 5, the valve hole 39 of the check valve 38 is blocked from the annular recess 31.

Therefore, the downward force applied to the valve body 41 of the check valve 38 becomes greater than the upward force, and the check valve 38 closes.

After the intake valve 5 is fully open, when the pressing force of the cam 9 on the lifter 13 is released, the intake valve 5 is driven upward by the spring force of the valve spring 7, that is, in the valve closing direction. This closing operation of the intake valve 5 also pushes the valve driving piston 29 upward, and the hydraulic oil in the damper chamber 28 is returned to the hydraulic oil chamber 27 via the oil passage 32.

During the closing operation of the intake valve 5, direct communication between the annular recess 31 and the damper chamber 28 is released, and the damper chamber 2
After the fixed orifice 34 and the variable orifice 36 are interposed between the damper chamber 8 and the annular recess 31, that is, the hydraulic oil chamber 27, the amount of hydraulic oil that returns from the damper chamber 28 to the hydraulic oil chamber 27 is limited. Therefore, the upward movement speed of the intake valve 5, that is, the valve closing speed, is slowed midway through the valve closing operation, and the intake valve 5 is seated gently on the valve seat member 4. Therefore, the impact upon seating is alleviated, and damage to the intake valve 5, valve seat member 4, etc. can be prevented as much as possible.

That is, as shown by the solid line in FIG. 4, when the intake valve 5 is closed, the hydraulic oil in the damper chamber 28 leaks while being restricted by the variable orifice 36 and the fixed orifice 34, and the hydraulic oil leaks. In response to this, the intake valve 5 closes, but at point P, which is just before the intake valve 5 is seated, the opening area of the variable orifice 36 becomes 0, and after that, in the area indicated by range B, only by the throttling action of the fixed orifice 34. Since the amount of hydraulic oil leakage is limited, in range B, the slope of the valve lift remains the same as at point P. Thus, the fixed orifice 34 is connected to the damper chamber 28 and the annular recess 31.
Since there is constant communication between the valve train, the dimensional accuracy of the valve train
It becomes possible to always keep the seating speed constant despite dimensional changes due to heat and wear changes.

By the way, in the check valve 38, the valve body 41 has the valve body 4.
1 and the hydraulic pressure of the damper chamber 28 act in the valve closing direction, and the hydraulic pressure of the valve hole 39 acts in the valve opening direction. Compared to the previously energized valve, the check valve 38 can be opened even when the hydraulic pressure in the valve hole 39 is relatively low when the intake valve 5 is fully closed, and when the hydraulic pressure from the hydraulic pressure generating means 10 is applied. The valve can be opened quickly and the hydraulic oil can be introduced into the damper chamber 28, and the valve opening operation becomes smooth. Also, the intake valve 5
After the annular recess 31 and the valve hole 39 are cut off while the valve is opening from the fully closed position, the downward force applied to the valve body 42 becomes greater than the upward force, and the valve body 42 is seated stably on the valve seat 40, so even without using a spring,
The valve can be stably maintained in a closed state.

In the above embodiments, a valve operating system for an intake valve has been described, but the present invention can be implemented similarly for a valve operating system for an exhaust valve. In addition, the hydraulic pressure generating means is not limited to one that generates hydraulic pressure using a cam as in each of the above embodiments.In addition, the hydraulic pressure from a hydraulic pressure generating source such as a hydraulic pump is controlled by a control valve and supplied to the damper chamber. It may be something.

C0 Effects of the Invention As described above, according to the present invention, the check valve includes a valve hole provided in the valve driving piston to communicate with the hydraulic pressure generating means from the fully closed state to the predetermined valve open state of the engine valve, and the valve hole. a valve seat provided at the edge of the opening to the damper chamber, a spherical valve body that can be seated on the valve seat and housed in the damper chamber, and a valve drive that holds the valve body in a free state so that it can open and close. Since it is equipped with a retainer that is fixed to the piston, the opening operation of the engine valve is
A check valve with smooth start-up can be configured compactly.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall longitudinal sectional side view, FIG. 2 is an enlarged vertical sectional view of the main part of FIG. 1, and FIG. 3 is an enlarged perspective view of a valve driving piston. FIG. 4 is a valve lift characteristic diagram. 5... Intake valve as an engine valve, 10... Hydraulic pressure generating means, 12... Cylinder body, 28... Damper chamber, 38
... Check valve, 39 ... Valve hole, 40 ... Valve seat,
41... Valve body, 42... Retainer

Claims (1)

[Claims] a damper chamber defined between the cylinder body and the valve drive piston, in which a valve drive piston, one end of which is interlocked and connected to the engine valve biased in the valve closing direction, is slidably fitted in the cylinder body; An internal combustion engine in which a check valve that only allows flow of hydraulic oil from the hydraulic pressure generating means to the damper chamber is interposed between the hydraulic pressure generating means that generates hydraulic pressure in accordance with the opening timing of the engine valve. In a valve train, a check valve is provided at a valve hole provided in a valve driving piston to communicate with a hydraulic pressure generating means from a fully closed state to a predetermined open state of an engine valve, and at an opening edge of the valve hole to a damper chamber. a spherical valve element that can be seated on the valve seat and housed in a damper chamber; and a retainer that is fixed to a valve driving piston to hold the valve element in a free state so that it can open and close. A valve train for an internal combustion engine characterized by: