JPH02283811A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate attaching/detaching work by mounting a sealing member for a valve stem part while fitting elastically a cylindrical part in the through hole of a piston, in a device in which a piston facing to an air pressure chamber where air pressure for energizating an engine valve in a closing valve direction is generated, is fixed to the valve stem part. CONSTITUTION:A lifter 12 is moved downward in response to slidable fitting to the high part 8b of a cam 8, and when an intake valve 5 is opened, a piston 16 fixed on a valve stem part 5a is moved downward while contracting the capacity of an air pressure chamber 13 so as to energize the intake valve 5 in a valve closing direction by air pressure generated in the air pressure chamber 13. And in a condition where a base disc part 8a is slidably fitting to a lifter 12, the lifter 12 is raised by air pressure of the air pressure chamber 13 so as to close the intake valve 5. In this case, a taper-type through hole 20 for pressure-fitting a cotter 19 in the central part of the piston 16 is formed, and a seal member 22 for a valve stem, which is constituted by providing a flange part 22b on a cylindrical part 22a, is fit in the through hole 20 so that the seal member 22 is interposed between inside face of through hole 20, and the outer surface of the valve stem part 5a.

Description

Detailed Description of the Invention A1 Objective 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. A drive member is in contact with the rear end of the shaft, and a piston that faces an air pressure chamber that generates air pressure that biases the engine valve in the valve-closing direction is fixed to the middle part of the valve shaft via a bolt. Regarding a valve device.

(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 By the way, this device biases the engine valve in the valve-closing direction by the air pressure in the air pressure chamber facing the piston, and the valve spring is This eliminates the problem of resonance limits due to natural frequencies and enables operation at higher rotation speeds. However, the piston is fixed to the middle part of the valve stem, and a sealing member must be interposed between the valve stem and the piston to prevent air from leaking from the pneumatic chamber at the fixed part. . Although the seal structure is not disclosed in the above-mentioned conventional valve, an O-ring is generally interposed between the valve stem and the piston. However, when an O-ring is used, it is necessary to provide a groove for fitting the O-ring on either the outer surface of the valve stem or the inner surface of the piston through-hole, which increases the number of machining steps and makes it difficult to attach and detach the O-ring. The operation is also complicated.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve train for an internal combustion engine, which is equipped with a sealing member interposed between a valve stem and a piston with a simple structure and easy to attach and detach. purpose.

B0 Structure of the Invention (1) Means for Solving the Problems According to the present invention, a tapered through hole is formed in the center of the piston and has a larger diameter at one end for press-fitting the cotter.
A valve shaft sealing member made of an elastic material is provided with a flange portion that contacts the center portion of the piston on a cylindrical portion formed in a substantially cylindrical shape to elastically fit into the other end of the through hole. It is interposed between the inner surface of the hole and the outer surface of the valve stem.

(2) Function According to the above configuration, the valve shaft sealing member is mounted by elastically fitting the substantially cylindrical portion into the through hole of the piston, and it is easy to attach and detach, and There is no need to provide a specially shaped mounting section on the valve stem or piston.

(3) Embodiment Below, an embodiment of the present invention will be explained with reference to the drawings. First, in FIG. An intake boat 4 is bored, and an intake valve 5 as an engine valve is connected to a guide tube 6 provided in the engine body 1 to open and close the intake valve port 3.
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 10 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 upwardly protruding portion 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, a piston 16 which is inserted into the lifter 12 while forming a cavity 15 between the closed end of the lifter 12 and the closed end of the lifter 12 is fixed. 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 retaining groove 18 is provided in a portion near the rear end of the valve shaft portion 5a, and the piston 16 is inserted into the valve shaft portion 5a via a two-piece lock 19 that engages with the retaining 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 groove 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 locking groove 18 into the through hole 20 from the cavity 15 side.

Incidentally, the air pressure chamber 1
In order to prevent air from leaking, an O-ring 21 surrounding the guide tube 6 is interposed between the joint surfaces of the engine body 1 and the hollow rib 10. In addition, in order to prevent the air in the pneumatic chamber 13 from leaking into the cavity 15 from between the cylinder 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 support part 14a, which is fitted in the annular groove 17 and has an oval-shaped cross section, has a diameter that increases as it goes downward so that the outermost periphery slides into contact with the inner surface of the sliding hole 11 under the pressure in the air pressure chamber 13. 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. However, the lower end position of the communication groove 23 is such that when the lifter 12 is in sliding contact with the inside 8a of the heel 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 fA 27 is connected to the sleeve 10 via a line 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, when 5 kg/cnl of pressurized air is supplied from the pressurized air supply source 27, and the check valve 25 is configured to allow the The valve will open on.

Further, a relief valve 29 is connected to the pneumatic chamber 13 via a relief passage 28 formed in the sleeve 10. The relief valve 29 is set to open at an opening pressure (for example, 16 kg/c4) 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 l 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 IO to be interposed between the relief passage 28 and a passage 30 opened to the outer surface and bored in the sleeve 10. 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 IO 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 cavity 15 communicates with the outside via the gap between the lifter 12 and the piston 16 and the communication groove 23, and therefore the pressure inside the cavity 15 increases abnormally. However, it is possible to prevent the lifter 12 from floating and causing noise. Furthermore, lifter 1
When assembling No. 2, it is sometimes possible to remove air from the empty chamber 15, and the pressure in the empty chamber 15 increases during the assembly, causing the piston 16 to
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 portion 16b, and is easy to attach and detach.Since there is no need to provide a specially shaped attachment section on the piston 16 side, the structure can be simplified and the weight can be reduced. This can contribute to reducing the amount of heat and machining process required. 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, the lubricating oil is smoothly supplied into the sliding hole 11, 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 13, 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 communicates with the pneumatic chamber 13 at a position below the predetermined amount of the lubricating oil level 2, so that the lubricating oil mainly flows through the relief passage 28, the relief valve 29, and the passage. 30 to the outside, thereby preventing the air inside the pneumatic chamber 13 from being released indiscriminately.

Moreover, the relief passage 2 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 shaft The lubricating oil necessary for lubrication between the portion 5a and the inner surface of the guide hole 9 remains in the recess 33, so that sufficient lubrication between the valve stem portion 5a and the sleeve 10 can be 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
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 shaft sealing member 22 comes into elastic contact with the bottom of the sliding hole 11 and can perform 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.

C2 Effects of the Invention As described above, according to the present invention, a tapered through hole with a large diameter at one end is bored in the center of the piston in order to press fit the cotter, and the other end of the through hole has an elastic hole. A valve shaft sealing member made of an elastic material is provided with a flange portion that contacts the center portion of the piston on a cylindrical portion that is formed into a substantially cylindrical shape so as to fit into the piston. Since the valve stem sealing member is interposed, it is easy to attach and detach the valve stem sealing member, which contributes to simplifying the structure and reducing weight and processing steps.Furthermore, the assembly of the cotter becomes easy to operate.

[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 shaft sealing member, and FIG. 3 is an enlarged view of part m in FIG. 1. , Figure 4 is I of Figure 1.
It is a VrV line arrow view.

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 shaft via a cotter, the center part of the piston has a tapered shape with one end having a larger diameter in order to press fit the cotter. made of an elastic material, the cylindrical portion is formed into a substantially cylindrical shape so as to fit elastically into the other end of the through hole, and a flange portion that contacts the central portion of the piston is provided. A valve operating device for an internal combustion engine, characterized in that a valve stem sealing member is interposed between an inner surface of a through hole and an outer surface of a valve stem.