JPH02283807A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To ensure a good lubricating action by scraping and dropping lubricating oil stuck on a sliding hole inner surface by a sealing member at the time of lowering of a piston, in a device in which, a piston which is face to an air pressure chamber for generating air pressure by which an engine valve is energized in a valve closing direction, is fixed on a valve stem part. CONSTITUTION:When a lifter 12 is moved downward in response to slidable fitting to the high part 8b of a cam 8 on a valve system cam shaft 7 so as to open an intake valve 5, a piston 16 fixed on a valve stem 5a is moved downward while contracting the capacity of an air pressure chamber 13, and the intake valve 5 is energized in its closing valve direction by air pressure generated in the air pressure chamber 13. And when a base disc part 8a is in a condition to fit slidably on the lifter 12, the lifter 12 is lifted by air pressure in the air pressure chamber 13 so as to close the intake valve 5. In this occasion, such a construction is provided that lubricating oil led from a communicating groove 23 is scraped and dropped by the lip part 14b of a sealing member 14 at the time of lowering of the piston 16, and the lip 14b gets over an oil film stuck on the inside surface of a sliding hole 11 at the time of rising of the piston 16, so that good lubricating action can be obtained.

Description

Detailed Description of the Invention A0 Object of the Invention (1) Industrial Application Field The present invention provides an engine valve in which an engine valve comprising a valve body provided at the tip of a valve stem is supported in an engine body so as to be openable and closable. The present invention relates to a valve operating system for an internal combustion engine in which a driving member is brought into contact with the rear end of a shaft portion, and a piston is fixed to an intermediate portion of the valve shaft portion facing an air pressure chamber that generates air pressure that biases the engine valve in the valve closing direction.

(2) Prior Art Conventionally, such a device has been used, for example, in U.S. Pat.
It is well known from the publication No.

(3) Problems to be Solved by the Invention This device uses air pressure in a pneumatic chamber facing a piston to bias an engine valve in the valve-closing direction. This eliminates the problem of resonance limits due to frequency and enables operation at higher rotation speeds. Incidentally, lubricating oil should be supplied between the piston and the inner surface of the sliding hole to ensure good lubrication, but the above-mentioned conventional devices do not disclose a configuration for supplying such lubricating oil. do not have.

The present invention has been made in view of the above circumstances, and provides a valve train for an internal combustion engine that has a simple configuration and can supply lubricating oil between a piston and a sliding hole to ensure good operation. The purpose is to

B1 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the sleeve fixed to the engine body includes:
A bottomed sliding hole is provided with a guide hole at the bottom that allows the valve stem to pass through the valve stem airtightly and freely, and can be freely slid into the sliding hole while forming an air pressure chamber between the valve stem and the bottom of the sliding hole. On the outer surface of the piston that is fitted into the piston, there is an annular seal member that has a lip portion whose outermost periphery slides into contact with the inner surface of the sliding hole and has a substantially U-shaped cross section that opens toward the air pressure chamber. is fitted.

(2) Effect According to the above configuration, the lubricating oil that is supplied between the sliding hole and the piston and adhered to the inner surface of the sliding hole is scraped downward by the lip portion of the sealing member when the piston descends, and the lubricating oil is scraped off when the piston is raised. The lip portion operates by overcoming the oil film formed on the inner surface of the sliding hole.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. An intake port 4 is bored therein, and an intake valve 5 serving as an engine valve opens and closes the intake valve port 3 through a guide tube 6 provided in the engine body I.
It is guided so that it can move up and down. That is, the intake valve 5 includes a valve body part 5b that can open and close the intake valve port 3 at the tip of a valve stem part 5a that is slidably inserted into a guide cylinder 6, and the valve stem part 5a can be moved up and down. driven by.

A valve camshaft 7 having an axis perpendicular to the valve shaft 5a is rotatably disposed above the valve shaft 5a of the intake valve 5, and the valve camshaft 7 is not shown. Rotationally driven by a crankshaft.

Further, the valve operating camshaft 7 is integrally provided with a cam 8 having a base interior 8a corresponding to the closing timing of the intake valve 5 and a high portion 8b corresponding to the opening timing of the intake valve 5.

On the other hand, a sleeve 1O is fixed to the upper part of the engine body 1 at a position corresponding to the intake valve 5. This sleeve 10 has a bottomed sliding hole 11 that opens upward and is coaxial with the valve stem 5a. A guide hole 9 is bored through the portion protruding upward from the guide hole 9 in a movable manner. In addition, a glue lid 12 is provided in the sliding hole 11 as a driving member formed in a cylindrical shape with a bottom.
are slidably fitted with the closed end in the upper position. The outer surface of the closed end of the lifter 12 is in sliding contact with the cam 8, and the inner surface of the closed end of the lifter 12 is in contact with the valve shaft portion 5 of the intake valve 5.
It is brought into contact with the rear end, that is, the upper end of a. Therefore cam 8
A lifter 12 is interposed between the valve stem portion 5a and the valve stem portion 5a.

Further, in a portion near the rear end of the valve shaft portion 5a, a pneumatic chamber 13 is formed between the valve shaft portion 5a and the bottom portion of the slide hole 11, and a seal member 14 made of an elastic material is fitted into the slide hole 11. At the same time, the piston 16 inserted into the lifter 12 is fixed while forming a cavity 15 between it and the closed end of the lifter 12. This piston 16 has an annular groove 1 into which the seal member 14 is fitted.
7 on the outer surface, an inner cylinder part 16b disposed coaxially with the outer cylinder part 16a, and a flat connecting plate part 16c connecting one end of the outer cylinder part 16a and the inner cylinder part 16b.
The connecting plate portion 16c is formed into a bottomed double cylindrical shape consisting of
It is fitted into the sliding hole 11 with the side facing the lifter 12. Moreover, the outer diameter of the portion of the outer cylinder portion 16a that is inserted into the glue lid 12 is
It is set to such an extent that a small annular gap is formed between the inner surface of the lifter 12 and the inner surface of the lifter 12 .

An annular engagement groove 18 is provided in a portion near the rear end of the valve stem 5a, and the piston 16 is inserted into the valve stem 5a via a two-piece lock 19 that engages with the engagement groove 18. It is fixed near the rear end. That is, the inner cylindrical portion 16b of the piston 16 is provided with a through hole 20 formed in a tapered shape that becomes smaller in diameter toward the air pressure chamber 13 side.
The outer surface of the kettle 19 is also formed in a tapered shape that becomes smaller in diameter toward the pneumatic chamber 13 side. The piston 16 is coaxially fixed to the valve shaft portion 5a by press-fitting the lever 19 that engages with the engagement groove 18 into the through hole 20 from the cavity 15 side.

By the way, the air pressure chamber 1 passes between the guide hole 9 and the valve stem 5a, and between the joint surfaces of the engine body l and the sleeve 10.
In order to prevent air leakage, an O-ring 21 surrounding the guide cylinder 6 is interposed between the joint surfaces of the engine body l and the sleeve lO. In addition, in order to prevent the air in the pneumatic chamber 13 from leaking into the cavity 15 from between the contour 19 and the outer surface of the valve stem portion 5a and the inner surface of the through hole 20, the inner end of the inner cylinder portion 16b of the piston 16 is provided with a valve stem. The sealing member 22 is attached. As shown in FIG. 2, the sealing member 22 is arranged radially outwardly at the pneumatic chamber 13 side end of the cylindrical portion 22a, which is formed in a substantially cylindrical shape so as to pass through the valve shaft portion 5a while closely contacting the outer surface thereof. The flange portion 22b that overhangs the
are integrally provided, and are made of an elastic material.

Furthermore, the outer surface of the cylindrical portion 22a is formed in a tapered shape that corresponds to the through hole 20 and becomes smaller in diameter toward the flange portion 22b.

In FIG. 3, a seal member 14 is fitted into an annular groove 17 provided on the outer surface of the outer cylinder portion 16a of the piston 16.
The outermost periphery of the supporting portion 14a, which is fitted in the annular groove 17 and has an oval-shaped cross section, slides into contact with the inner surface of the sliding hole 11 under the pressure in the air pressure chamber 13 (the diameter increases as it goes downward). The small-diameter ends of the lip portion 14b are connected to each other, and the lip portion 14b has a substantially U-shaped cross section that opens toward the air pressure chamber 13.

In FIG. 4, a communication groove 23 is formed in the inner surface of the sliding hole 11 in the sleeve 10 and extends in the axial direction so that the upper end communicates with the outside. Moreover, the lower end position of the communication groove 23 is such that when the lifter 12 is in sliding contact with the base interior 8a of the cam 8 and the intake valve 5 is in the closed state, that is, when the piston 16
is in the uppermost position, the empty space 1 is inserted between the lifter 12 and the piston 16 at a position above the seal member 14.
It is set to communicate with 5.

A pressurized air supply source 27 is connected to the sleeve IO via a conduit 26 provided with a check valve 25.

This check valve 25 only controls the flow of air from the pressurized air supply source 27 into the air pressure chamber 13 when the air pressure within the air pressure chamber 13 becomes lower than the air pressure of the pressurized air supply source 27 by a certain pressure or more. For example, pressurized air of 5 kg/cd is supplied from the pressurized air supply source 27, and the check valve 25 is configured so that the internal pressure of the air pressure chamber 13 is 4 kg/cd.
The valve opens when it becomes less than kg/cd.

Further, a relief valve 29 is connected to the pneumatic chamber 13 via a relief passage 28 formed in the sleeve IO. This relief valve 29 is set to open at an opening pressure (for example, 16 kg/d) corresponding to the maximum pressure inside the pneumatic chamber 13 when a predetermined amount of lubricating oil is accumulated in the pneumatic chamber 13. The relief passage 28 is formed in the sleeve 10 at a position below the oil level 1 of the lubricating oil collected in the predetermined amount in the pneumatic chamber 13 and above the guide hole 9 so as to communicate with the pneumatic chamber 13.

The relief valve 29 is disposed in the sleeve 10 so as to be interposed between the relief passage 28 and a passage 30 opened to the outer surface and bored in the sleeve 1O. 30, a spherical valve body 31 that can communicate with and shut off the valve body 30, and a spring 3 that biases the valve body 31 in the valve closing direction.
2.

Incidentally, a recess 33 is provided at the center of the bottom of the sleeve 10 so as to surround the valve shaft portion 5a that penetrates the guide hole 9 and protrudes into the pneumatic chamber 13.

Next, the operation of this embodiment will be explained. When the valve drive camshaft 7 is rotationally driven by the crankshaft, the lifter 12 is driven to be pressed downward in accordance with the sliding contact with the high part 8b of the cam 8. As a result, the valve stem portion 5a of the intake valve 5 is pushed downward, and the intake valve 5 is operated to open.

At this time, the piston 16 fixed to the rear end portion of the valve stem 5a is also pushed downward while contracting the volume of the air pressure chamber 13, and air pressure is generated in the air pressure chamber 13.

As a result, the intake valve 5 is urged upward by the air pressure, that is, in the valve closing direction, and the cam 8 opens the intake valve 5 against the urging force in the valve closing direction due to the air pressure.

Therefore, when the cam 8 rotates to a position where the base interior 8a comes into sliding contact with the lifter 12, the lifter 12 rises due to the air pressure in the air pressure chamber 13 so as to come into sliding contact with the base interior 8a.
The intake valve 5 is closed.

With this structure in which the intake valve 5 is biased in the closing direction by air pressure, compared to a structure in which the valve is biased to close using a valve spring, there is no need to consider the resonance limit due to the natural frequency, so the engine It becomes possible to operate at higher rotation speeds.

Moreover, according to such a valve train, the lifter 12 is also slidably fitted into the sliding hole 11 of the sleeve 10 into which the piston 16 is fitted, so that the structure guides the lifter 12 to a position above the sleeve 10. Compared to a valve equipped with a valve, the entire valve can be made more compact, and the length of the valve stem portion 5a can be shortened to accommodate higher rotation speeds.

Furthermore, when the intake valve 5 is in the closed state, the empty chamber 15 communicates with the outside via the gap between the lifter 12 and the piston 16 and the communication groove 23, so that the pressure inside the empty chamber 15 becomes abnormal. This makes it possible to prevent the lifter 12 from floating and causing noise. Furthermore, lifter 1
When assembling item 2, it is sometimes possible to remove air from the empty chamber 15, and during the assembly, the pressure in the empty chamber 15 increases and the piston]6
This also prevents the lifter 12 from separating from the valve stem portion 5a.
At the time of removal, air is introduced into the chamber 15 to prevent the chamber 15 from being depressurized, thereby making the removal work easier.

Further, the valve shaft sealing member 22 has a cylindrical portion 22 a formed in a substantially cylindrical shape corresponding to the through hole 20 of the piston 16 that is elastically fitted from the air pressure chamber 13 side to the inside of the piston 16 . It is attached to the inner end of the cylindrical part 16b, and it is easy to attach and detach, and there is no need to provide a special shaped attachment part on the piston [6 side, so the structure can be simplified. It can contribute to weight reduction and processing man-hour reduction. Moreover, the valve stem sealing member 22 exerts a resilient force when attached to the piston 16, and the piston 16 can be held on the valve stem 5a. 20 becomes easy to press fit. Moreover, the flange portion 22b of the valve stem sealing member 22 is brought into close contact with the inner end of the inner cylinder portion 16b by the air pressure within the air pressure chamber 13, and exhibits a sufficient sealing effect.

By the way, the communication groove 23 introduces a part of the lubricating oil supplied toward the sliding surfaces of the cam 8 and the lifter 12 into the sliding hole 11 as lubricating oil between the inner surface of the sliding hole 11 and the piston 16. It also serves a function. Then piston 1
6 The sealing member 14 fitted on the outer surface of the air pressure chamber 1
The outermost periphery of the lip portion 14b is in sliding contact with the inner surface of the sliding hole 11, so that when the piston 16 descends, that is, the intake valve 5 is opened. At this time, the lip portion 14b scrapes the lubricating oil introduced from the communication groove 23 downward, and the piston 16
When the intake valve 5 rises, that is, when the intake valve 5 closes, the lip portion 14b operates to overcome the oil film attached to the inner surface of the sliding hole 11.

Therefore, lubricating oil is smoothly supplied into the sliding hole 1.1, and the lubrication between the piston 16 and the inner surface of the sliding hole 11 is improved.

When the lubricating oil supplied in this manner accumulates in the pneumatic chamber I3, the maximum pressure in the pneumatic chamber 13 when the intake valve 5 is opened to its maximum also increases.

As a result, more than a predetermined amount of lubricating oil accumulates in the pneumatic chamber 13,
When the maximum pressure in the air pressure chamber 13 exceeds the opening pressure of the relief valve 29, the relief valve 29 opens. When the relief valve 29 is opened, the relief passage 28 reaches a predetermined amount of i.
Since the lubricating oil is communicated with the pneumatic chamber 13 at a position lower than the lubricating oil gap 2, the lubricating oil is mainly released to the outside through the relief passage 28, the relief valve 29, and the passage 30, and the lubricating oil is This prevents the air inside from being released indiscriminately.

Moreover, the relief passage 28 communicates with the air pressure chamber 13 at a position above the guide hole 9, and a recess 33 is provided at the bottom of the sliding hole 11 at a position above the guide hole 9, so that the valve stem The lubricating oil necessary for lubrication between the inner surface of the valve stem 5a and the guide hole 9 remains in the recess 33, and the lubrication between the valve stem 5a and the sleeve 10 can be sufficiently achieved.

Furthermore, when the air in the pneumatic chamber 13 decreases due to leakage or the like, pressurized air is supplied into the pneumatic chamber 13 from the pressurized air supply source 27 via the check valve 25, so that the minimum pressure in the pneumatic chamber 13 is maintained. This makes it possible to secure a biasing force sufficient to reliably close the intake valve 5.

In the above embodiment, the lifter 12 is slidably fitted into the sliding hole 11, but the part that guides the lifter 12 is replaced by the sleeve I.
It may be provided at a position above O. At that time, the valve stem seal member 22 may be placed at the lowest position of the piston 16, but in such a case, the valve shaft seal member 22 may be placed in the lowermost position of the piston 16.
When the valve shaft sealing member 22 is press-fitted from above, the valve stem sealing member 22 comes into elastic contact with the bottom of the sliding hole 11 to provide a buffering effect.

The present invention is also applicable to a valve operating device for an exhaust valve. Furthermore, instead of having the cam slide into direct contact with the lifter,
The present invention is also applicable to a valve train in which power from a cam is applied to a lifter via a rocker arm as a driving member.

C0 Effects of the Invention As described above, according to the present invention, the sleeve fixed to the engine body has a bottomed sliding hole having a guide hole at the bottom that allows the valve stem to pass through the valve shaft airtightly and movably. The outer surface of the piston, which is provided and slidably fitted into the sliding hole while forming an air pressure chamber between it and the sliding bottom, has a lip portion whose outermost periphery is brought into sliding contact with the inner surface of the sliding hole. At the same time, an annular seal member having a substantially U-shaped cross section that opens toward the air pressure chamber is fitted, so that the lubricating oil supplied between the sliding hole and the piston is transferred to the lip of the seal member. The valve can be fed to the bottom side of the sliding type by its action, and the simple structure ensures lubrication between the piston and the sliding hole, as well as the lubrication between the valve stem and sleeve to ensure good operation. I can do it.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall longitudinal sectional side view, FIG. 2 is an enlarged longitudinal sectional view of a valve stem sealing member, and FIG. 3 is an enlarged top view of FIG. 1. Figure 4 is the same as in Figure 1.
- It is a view taken along the line IV.

Claims (1)

[Claims] An engine valve consisting of a valve body provided at the tip of a valve stem is supported by the engine body so that it can be opened and closed, and a driving member is brought into contact with the rear end of the valve stem to bias the engine valve in the closing direction. In a valve operating system for an internal combustion engine in which a piston facing an air pressure chamber that generates air pressure is fixed to the middle part of the valve stem, a sleeve fixed to the engine body is passed through the valve stem in an airtight and movable manner. A bottomed sliding hole with a guide hole at the bottom is provided, and the outer surface of the piston, which is slidably fitted into the sliding hole while forming an air pressure chamber between the bottom and the bottom of the sliding hole, has an outermost periphery. An internal combustion engine characterized in that an annular sealing member having a substantially U-shaped cross section opening toward an air pressure chamber and having a lip portion that slides into contact with an inner surface of a sliding hole is fitted. Valve train.