JPH02283806A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable an engine to rotate at a high speed, by providing such constitution that an engine valve is opened while contracting an air pressure chamber capacity by a piston in response to pushing of a lifter by a driving member so as to close the engine valve by air pressure in the air pressure chamber, which is generated following the contruction. CONSTITUTION:When a valve system cam shaft 7 is rotated by a crank shaft a lifter 12 is moved downward in response to slidable fitting of a cam 8 to the high part 8b so as to open an intake valve 5. At that time, a piston 16 fixed on the rear end side of a valve shaft part 5a, is also moved downward while contracting the capacity of an air pressure chamber 13, so that air pressure is generated in the air pressure chamber 13. Therefore, the intake valve 5 is energized in a closing valve direction by air pressure, and the intake valve 5 is opened by the cam 8 opposing to the energizing fore of the closing valve direction. And, when a base circular part 8a comes in a condition to fit slidably on the lifter 12, the lifter 12 is raised so as to fit slidably on a base edge 8a by air pressure in the air pressure chamber 13, so that the intake valve 5 is closed.

Description

[Detailed Description of the Invention] A8 Object of the Invention (1) Industrial Field of Application The present invention provides an engine valve having a valve body provided at the tip of a valve stem, which is elastically biased in the valve closing direction. The present invention relates to a valve operating system for an internal combustion engine, which is supported in an openable and closable manner on an engine body, and in which a driving member for driving the engine valve in the opening direction is interlocked and connected to the rear end of the valve shaft.

(2) Prior Art Conventionally, such devices have been disclosed in Japanese Patent Application Laid-Open No. 64-36906, for example.
It is well known from the publication No.

(3) Problems to be Solved by the Invention However, in the above-mentioned conventional device, the engine valve is biased in the valve closing direction by the valve spring, and the engine valve is driven in the valve opening direction by the driving member against the biasing force of the spring. I try to do that. However, in the case where such a spring force is used, there is a limit to the natural frequency of the valve spring, so that it may be difficult to operate the engine valve in response to high rotational speeds of the engine.

Therefore, as shown in FIG. 5, a prior art technique has been implemented in which an air spring is used to bias the engine valve in the valve-closing direction. In this prior art, a bottomed cylindrical lid 12 driven by a cam 8 serving as a driving member is slidably fitted into a guide hole 35 provided in the engine body 1, and the valve shaft of an intake valve 5 or an exhaust valve is The valve shaft portion 5 is brought into contact with the rear end of the portion 5a.
A piston 16 fixed in the middle of a is slidably fitted into the sleeve 10 with its front surface facing the pneumatic chamber 13.

According to such a configuration of the prior art, the air pressure in the air pressure chamber 13 biases the intake valve 5 or the exhaust valve in the valve closing direction, and there is no need to consider the resonance limit due to the natural frequency, so the engine can be rotated at higher speeds. It becomes possible to drive. However, a portion for guiding the valve shaft portion 5a of the intake valve 5 or the exhaust valve must be provided above the sleeve 10 in the engine body 1, and the overall height increases accordingly.

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 that is compact and capable of increasing the rotation speed of the engine.

B0 Structure of the Invention (1) Means for Solving the Problems According to the first feature of the present invention, the sleeve fixed to the engine main body has a guide hole through which the valve shaft portion can pass airtightly and freely. A bottomed cylindrical lifter is provided between the drive member and the rear end of the valve stem, and a bottomed cylindrical lifter is provided to be slidably fitted into the sliding hole. A piston, which is fitted into the sliding hole via a sealing member and inserted into the lifter while forming a pneumatic chamber between the piston and the bottom of the hole, is fixed near the rear end of the valve stem.

According to a second feature of the present invention, in addition to the structure of the first feature, the inner surface of the sliding hole is provided with a communication groove that can communicate between the lifter and the piston on the lifter side than the seal member. Open to the outside and drilled.

(2) Effect According to the configuration of the first feature, the engine valve is driven in the valve opening direction while contracting the pneumatic chamber volume by the piston in response to the lifter being pressed by the drive member, and as the lifter is pressed by the drive member, the engine valve is driven in the valve opening direction. The air pressure generated in the air pressure chamber urges the engine valve in the valve closing direction.

Furthermore, since the lifter into which a portion of the piston is inserted is slidably fitted into the sliding hole of the sleeve, it is not necessary to provide a special portion for guiding the lifter above the engine valve.

Further, according to the configuration of the second feature, the cavity created between the lifter and the piston can be communicated with the outside through the communication groove, and pressurization and depressurization of the cavity can be avoided.

(3) Embodiment Hereinafter, 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 l 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.

Furthermore, the valve drive camshaft 7 is integrally equipped with a cam 8 as a driving member, which has a base interior 8a corresponding to the closing timing of the intake valve 5 and a high portion 8b corresponding to the closing timing of the intake valve 5. provided.

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. Furthermore, a lifter 12 formed in the shape of a cylinder with a bottom is slidably fitted into the sliding hole 11 with its closed end positioned upward. 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 rear end, that is, the upper end of the valve shaft portion 5a of the intake valve 5. Therefore, the cam 8 and the valve shaft portion 5a
A lifter 12 will be interposed between them.

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 nuclear 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 portion 5a, and the piston 16 is inserted into the valve stem portion 5a via a split collar 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 1 and the sleeve 10.
In order to prevent air leakage, an O-ring 21 surrounding the guide tube 6 is interposed between the joint surfaces of the engine body 1 and the sleeve 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 22ae is formed in a tapered shape that corresponds to the through hole 20 and becomes smaller in diameter toward the flange portion 22b side.

In Figure 3, the piston! A sealing member 14 fitted into an annular groove 17 provided on the outer surface of the outer cylinder portion 16a in 6
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. 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, the pressurized air supply source 27 supplies pressurized air at a rate of 5 kg/cd, and the check valve 25 operates when the internal pressure of the air pressure chamber 13 becomes 4 kg/cd or less. Open the valve.

Further, a relief valve 29 is connected to the pneumatic chamber 13 via a relief passage 28 formed in the sleeve 10. This relief valve 29 is set to open at an opening pressure (for example, 16 kg/cd) corresponding to the maximum pressure inside the pneumatic chamber 13 when a predetermined amount of lubricating oil has accumulated in the pneumatic chamber 13. , the relief passage 28 is connected to the pneumatic chamber 1
A hole is formed in the sleeve 10 to communicate with the air pressure chamber 13 at a position below the oil level l of the lubricating oil collected in the predetermined amount in the sleeve 3 and above the guide hole 9.

The relief valve 29 is disposed in the sleeve IO to be interposed between the relief passage 2B and a passage 30 opened to the outer surface and bored in the sleeve 10, and the relief passage 28 and a spherical valve body 31 that can communicate and shut off the passages 30, and a spring 32 that biases the valve body 31 in the valve closing direction.

Incidentally, a recess 33 is provided at the center of the bottom of the sleeve 1O so as to surround the valve shaft 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 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 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 way 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 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 attached to the sleeve 1.
It may be provided at a position above 0. 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.

Although the above embodiments have been described with reference to the intake valve 5 as an engine valve, the present invention is also applicable to a valve operating system for an exhaust valve. Furthermore, the present invention is also applicable to a valve train in which power from the cam is applied to the lifter via a rocker arm as a driving member instead of having the cam directly in sliding contact with the lifter.

C1 Effects of the Invention As described above, according to the first feature of the present invention, the sleeve fixed to the engine body has a bottomed guide hole that allows the valve stem to pass through the valve shaft airtightly and movably. A bottomed cylindrical lifter is provided between the drive member and the rear end of the valve stem, and the bottomed cylindrical lifter is slidably fitted into the slide hole. The piston, which is fitted into the sliding hole via a sealing member while forming a pneumatic chamber and inserted into the lifter, is fixed near the rear end of the valve stem, so it guides the valve stem of the engine valve. Since it is not necessary to provide a portion above the sleeve, the overall height can be reduced, and the length of the valve stem can be shortened to accommodate higher rotations.

According to the second feature of the present invention, on the inner surface of the sliding hole,
Since a communication groove that can communicate between the lifter and the piston is opened to the outside and is bored on the lifter side than the seal member,
By avoiding pressurization and depressurization of the space between the piston and the lifter, it is possible to easily attach and detach the lifter to and from the sliding hole, and to prevent dancing and noise caused by the lifting of the lifter, and also to improve communication. Lubricating oil can also be supplied into the sliding hole from the groove.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is an overall longitudinal sectional side view, FIG. 2 is an enlarged longitudinal sectional view of a valve stem seal member, and FIG. Enlarged view of the ■ part of the figure, No. 4
1 is a view taken along the line IV-IV in FIG. 1, and FIG. 5 is a longitudinal sectional side view of the prior art. l... Engine body, 5... Intake valve as engine valve, 5
a... Valve stem portion, 5b... Valve body portion, 8... Cam as a driving member, 9... Guide hole, 10... Sleeve,
DESCRIPTION OF SYMBOLS 11...Sliding hole, 12...Lifter, 13...Pneumatic chamber, 14...Sealing member, 16...Piston, 2
3... Kendo Ochiai, Physician, Physician, as agent for applicant Honda Motor Co., Ltd. 1) Takahide Naka, Figure 4, Figure 5, Figure 1

Claims (2)

[Claims] (1) An engine valve consisting of a valve body provided at the tip of the valve stem is supported in the engine body so as to be openable and closable while being elastically biased in the valve-closing direction, and the rear end of the valve stem is In a valve operating system for an internal combustion engine in which a driving member for driving a valve in the opening direction is interlocked and connected, a sleeve fixed to the engine body has a guide that allows the valve shaft to pass through the valve shaft in an airtight and movable manner. A bottomed sliding hole having a hole at the bottom is provided, and a bottomed cylindrical lifter that is slidably fitted into the sliding hole is interposed between the driving member and the rear end of the valve shaft, and The piston is fitted into the sliding hole via a sealing member while forming a pneumatic chamber with the bottom of the sliding hole, and is inserted into the lifter, and is fixed near the rear end of the valve shaft. Valve gear for internal combustion engines. (2) Item (1), characterized in that a communication groove is formed on the inner surface of the sliding hole so as to be open to the outside and can communicate between the lifter and the piston on the side closer to the lifter than the seal member. valve train for internal combustion engines.