JPH0539704A - Valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To stabilize air pressure in an air pressure chamber by providing, on a sealing member, two lip parts inclined in a direction for allowing their opening toward the inner surface of a sliding hole, in the valve system of an internal combustion engine, wherein an annular sealing member which is in sliding contact with the inner surface of the sliding hole is fit on the outer surface of a piston. CONSTITUTION:An engine valve 8 which is constructed by providing its valve body part 8b on the top end of a valve stem part 8a, is supported on an engine main body 1 so as to open/close freely. A driving member 14 abuts on the rear end of the valve stem part 8a. A sliding hole 13 is provided on a sleeve 12. An air pressure chamber 15 is formed between the upper part and the bottom part of the sliding hole 13. A piston 18 is fixed on the valve stem part 8a. An annular seal member 161 which is in sliding contact with the inner surface of the sliding hole 13 is fit on the outer surface of the piston 18. Two lip parts 161b, 161c are provided to incline in directions for allowing their opening toward the inner surface of the sliding hole 13. It is thus possible to prevent air pressure from leaking from the air pressure chamber 15 certainly by the first lip part 161b. Also, it is possible to prevent lubricating oil from invading into the air pressure chamber 15 certainly by the second lip part 161c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve in which a valve body portion is provided at the tip of a valve shaft portion so as to be openable and closable in an engine body, and a drive member is brought into contact with a rear end of the valve shaft portion. , The sleeve fixed to the engine body is provided with a bottomed sliding hole, and an air pressure chamber that generates air pressure that urges the engine valve in the valve closing direction is formed between the sliding hole and the bottom of the sliding hole for sliding. The piston, which is slidably fitted in the hole, is fixed to the valve shaft that penetrates the sleeve fluid-tightly and movably into the sliding hole, and slides on the inner surface of the sliding hole on the outer surface of the piston. The present invention relates to a valve operating device for an internal combustion engine in which an annular seal member that is in contact is fitted.

[0002]

2. Description of the Related Art Conventionally, such a valve operating device has been already known from, for example, Japanese Patent Laid-Open No. 2-283807.

[0003]

In such a valve operating system, the engine valve is biased in the valve closing direction by the air pressure of the air pressure chamber facing the piston, and the valve spring which is to be considered in the valve operating system using the valve spring is unique to the valve operating system. It solves the problem of resonance limit due to frequency and enables operation at higher speeds. By the way, such a valve gear is installed in a lubricating oil atmosphere, and lubricating oil is introduced between the piston and the inner surface of the sliding hole.
In the above-mentioned conventional technique, an annular seal member which is slidably contacted with the bottom surface of the sliding hole and fitted on the outer surface of the piston is a transverse opening which opens toward the air pressure chamber side so that the outermost periphery is slidably contacted with the inner surface of the sliding hole. The surface is formed in a substantially U shape, and the lubricating oil introduced between the sliding hole and the piston and adhering to the inner surface of the sliding hole is scraped down by the seal member when the piston descends. However, if lubricating oil enters the pneumatic chamber,
Since the volume of the pneumatic chamber decreases by the volume occupied by the lubricating oil and the pressure inside the pneumatic chamber becomes unstable, it is necessary to provide a relief valve or the like for discharging the lubricating oil from the pneumatic chamber.

The present invention has been made in view of the above circumstances, and provides a valve operating device for an internal combustion engine, which realizes a reliable sealing of the pneumatic chamber and prevention of intrusion of lubricating oil into the pneumatic chamber with a simple structure. The purpose is to

[0005]

In order to achieve the above object, according to the present invention, the seal member is provided with two lip portions that are inclined in the opening direction toward the inner surface of the sliding hole.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a valve operating device, and FIG. 2 is FIG.
2 is an enlarged view of part 2 of FIG. 3, and FIG. 3 is an enlarged view of part 3 of FIG.

First, in FIG. 1, an engine main body 1 is provided with an intake port 6 communicating with an intake valve port 5 arranged facing the ceiling surface of a combustion chamber 4, and an intake valve 8 as an engine valve is provided.
Is guided by a guide cylinder 9 provided in the engine body 1 so as to open and close the intake valve port 5 so as to be vertically movable. That is, the intake valve 8 is formed by providing a valve body portion 8 _b capable of opening and closing the intake valve opening 5 at the tip of _a valve shaft portion 8 _a slidably inserted into the guide cylinder 9. _a is driven up and down.

[0009] The upper position of the valve shaft portion 8 _a in the intake valve 8, the valve operating cam shaft 10 having an axis orthogonal to the valve shaft portion 8 _a is disposed rotatably, animal valve cam The shaft 10 is rotationally driven by a crank shaft (not shown). Moreover the animal valve camshaft 10, provided a base circle portion 11 _a corresponding to the closing timing of the intake valve 8, the cam 11 having a high portion 11 _b is integrally corresponding to the valve opening timing of the intake valve 8 Be done.

On the other hand, a sleeve 12 is fixed to the upper portion of the engine body 1 at a position corresponding to the intake valve 8. A sliding hole 13 having a bottom, which opens upward, is formed in the sleeve 12 so as to form the valve shaft portion 8.
It is formed in _a coaxially, the rear end i.e. the upper end of the valve shaft portion 8 _a is rush coaxially within the slide hole 13 to move freely through the bottom of the sleeve 12. Moreover, a lifter 14 as a drive member formed in a cylindrical shape with a bottom is slidably fitted in the sliding hole 13 with the closed end of the lifter 14 as an upper position. The outer surface of the closed end of the lifter 14 is brought into sliding contact with the cam 11, and the inner surface of the closed end of the lifter 14 is brought into contact with the rear end or upper end of the valve shaft portion 8 _a of the intake valve 8. Hence the lifter 14 is interposed between the cam 11 and the valve shaft portion 8 _a.

[0011] Referring also to FIG. 2, the rear end portion of the valve shaft portion 8 _a, the air pressure chamber between the bottom of the slide hole 13 1
5 is an annular seal member 16 ₁ made of an elastic material.
The piston 18 inserted into the lifter 14 is fixed by being fitted into the sliding hole 13 via the through hole and forming an empty chamber 17 with the closed end of the lifter 14. This piston 18
An outer cylinder portion 18 _a having a small-diameter portion 19 for fitting the seal member 16 ₁ to the lower end outer surface, the inner cylinder portion 18 _b disposed on the outer cylinder portion 18 _a coaxial, outer cylindrical portion 18 _a and the inner cylinder part 18 _b is formed in a bottomed double cylindrical shape composed of a plate-shaped connecting plate portion 18 _c for connecting the one end of the connecting plate portion 18 _c lifter 14
The sliding hole 13 is fitted to the side. Moreover, the outer cylinder _18a
Wherein the upper position of the seal member 16 ₁ of the lifter 1
An O-ring 20 that is in sliding contact with the inner surface of 4 is fitted.

Seal member 16₁Is a metal reinforcing member 21.
Is formed by being embedded in an elastic material such as rubber.
The small diameter portion 19 of the piston 18 is elastically fitted.
Cylindrical base 16_1aAnd open toward the inner surface of the sliding hole 13.
Having a substantially V-shaped cross section_1aFrom side to side
Protruding first lip portion 16_1bAnd the second lip portion 16 _1c
With. That is, the first lip portion 16_1bIs the sliding hole 1
3 is formed so as to be inclined downward toward the inner surface,
2 lip part 16_1cAs it goes toward the inner surface of the sliding hole 13.
And is formed to be inclined upward. Thus, the reinforcing member 21
Sealing member 16 ₁Base 16 of_1aAnd both lip parts 16_1b，
16_1cBase 16 of_1aSo as to reinforce the connection part with
Sealing member 16₁It is buried inside.

Referring again to FIG. 1, the valve shaft portion 8_aToward the rear end
An annular engaging groove 22 is provided in the portion of
The pistol is inserted through the split cotter 23 that engages with the mating groove 22.
18 is the valve shaft portion 8_aIt is fixed to the part near the rear end. sand
Inner tube portion 18 of the piston 18_bIn the pneumatic chamber
It is formed in a taper shape whose diameter decreases toward the 15 side.
Through hole 24 is provided, and the outer surface of the cotter 23 is also empty.
The taper shape has a smaller diameter toward the pressure chamber 15 side.
Is made. Thus, the cotter 23 that engages with the engagement groove 22 is emptied.
By press fitting into the through hole 24 from the chamber 17 side, the piston
18 is the valve shaft portion 8 _aFixed coaxially to.

By the way, the air in the air pressure chamber 15 is discharged from the cotter 2.
From between 3 and valve stem 8 _a outer surface and the through-hole 24 the inner surface in order to prevent leaking air chamber 17, the inner end of the inner cylindrical portion 18 _b of the piston 18 wearing the valve shaft seal member 25 To be done. The seal member 25 is for pneumatic chamber 15 side corresponding to the through-hole 24 has a cylindrical shape surrounding the valve shaft portion 8 _a is formed of an elastic material with a tapered shape whose diameter, its length Is set so that the end portion on the air pressure chamber 15 side does not project from the lower end of the inner tubular portion 18 _b to the air pressure chamber 15 side.

In FIG. 3, a cylindrical portion 26 projecting into the pneumatic chamber 15 is coaxially provided at the bottom of the sliding hole 13, that is, the lower end of the sleeve 12, and the valve shaft is provided at the upper end of the cylindrical portion 26. the flange portion 27 forming a hole 28 in the inner edge of moving freely through the section 8 _a is provided projecting Te integrally radially inwardly. The upper portion of a guide cylinder 9 fixed to the engine body 1 is inserted into the cylindrical portion 26, and the guide cylinder 9 and the collar portion 27 are clamped between the guide cylinder 9 and the annular valve shaft. The seal member 29 is inserted into the cylindrical portion 26. The seal member 29 Thus is of a V-shaped having a lip portion 29 _a which elastically sliding contact with the outer surface of the valve shaft portion 8 _a, the metallic reinforcing member 30 is embedded. Moreover, a coating layer 31 made of a fluororesin or the like is provided on the inner surface of the lip portion 29 _a of the seal member 29 and the contact surface with the guide tube 9.

The valve shaft seal member 29 is pinched between the flange portion 27 and the guide cylinder 9, so that the contact surface 32 with the flange portion 27, the contact surface 33 with the inner surface of the cylindrical portion 26, and the guide. The contact surface 34 with the cylinder 9 and the contact surface 35 of the lip portion 29 _{a with} the valve shaft portion 8 _a can perform a sealing function, respectively, and the air from the air pressure chamber 15 is surely prevented from leaking. together we are also reliably prevents the lubricating oil between the guide tube 9 and the valve stem 8 _a from entering the pneumatic chamber 15 side.

[0017] Next, to explain the action of this first embodiment, the valve operating cam shaft 10 is rotated by the crankshaft, the lifter 14 in accordance with the sliding of the higher portion 11 _b of the cam 11 downwardly to the press drive, whereby the valve shaft portion 8 _a of the intake valve 8 is pressed driven downward, the intake valve 8 is opened actuated.

[0018] At this time, the piston 18 which is secured to the rear end portion of the valve shaft portion 8 _a is also pressed driven downward while contracting the volume of the pneumatic chamber 15, the air pressure is generated in the air pressure chamber 15. As a result, the intake valve 8 is biased upward by the air pressure, that is, in the valve closing direction, and the cam 11 drives the intake valve 8 to open against the biasing force of the air pressure in the valve closing direction. Therefore, when the cam 11 is rotated to the position where the base circular portion 11 _a is in sliding contact with the lifter 14, the lifter 14 is moved by the air pressure in the air pressure chamber 15 to cause the base circular portion 11 a to move.
rises as sliding contact with the _a, the intake valve 8 is closed.

According to the structure in which the intake valve 8 is biased in the valve closing direction by the air pressure as described above, the resonance limit due to the natural frequency is not taken into consideration, as compared with the structure in which the valve spring is used to bias the valve closing. The good result allows the engine to run at higher speeds.

According to such a valve operating device, the lifter 14 is slidably fitted in the sliding hole 13 of the sleeve 12 into which the piston 18 is fitted, so that the lifter 14 is guided to a position above the sleeve 12. Compared with the one with the structure
Overall compaction is possible, it is possible to cope with high rotation more to shorten the length of the valve shaft portion 8 _a.

The valve shaft seal member 25 is composed of the piston 1
And upper elastic fitting from engagement to 8 holes 24 of is intended to be attached to the inner cylindrical portion 18 _b in the end of the piston 18, together with the detachment operation is easy, the mounting portion of the special shape on the piston 18 side Since it is not necessary to provide the structure, the structure can be simplified, and the weight can be reduced and the number of processing steps can be reduced. Moreover, the valve shaft seal member 25 is used for the piston 1
In the mounted state to 8 is intended to exert a resilient force, it is possible to hold the piston 18 in the valve stem 8 _a, the operation of press-fitting into the through hole 24 of the cotter 23 during assembly is facilitated.

Further, a lifter 14 is provided on the outer surface of the piston 18.
Since the O-ring 20 slidingly contacting the inner surface of the
By using the ring 20 as a cushioning material, it is possible to prevent the piston 18 from collapsing, thereby stabilizing the sealing function of the seal member 16 _{1 and} improving the performance. Moreover, when the engine is left for a long period of time, the air pressure chamber 15
The pressure of the piston 1 decreases, and if some shock is applied from the outside at this time, the cotter 23 separates from the through hole 24 and the piston 1
There is a risk that the intake valve 8 will fall out due to the lowering of the intake valve 8. However, since the O-ring 20 elastically contacts the inner surface of the lifter 14, the relative position of the lifter 14 and the piston 18 can be maintained to prevent the intake valve 8 from falling off.

Moreover, in the seal member 16 ₁ , the first lip portion 16 _1b is inclined downward toward the inner surface of the sliding hole 13, and is strongly pressed against the inner surface of the sliding hole 13 by the air pressure in the air pressure chamber 15. Therefore, it is possible to reliably seal the air pressure in the air pressure chamber 15.
The second lip portion 16 _1b is located above the first lip portion 16 _1b.
1c is inclined upward as it goes to the inner surface of the sliding hole 13 and scrapes up the lubricating oil adhering to the inner surface of the sliding hole 13 when the piston 18 rises, so that the lubricating oil penetrates into the pneumatic chamber 15. The air pressure chamber 15
It is possible to prevent the volume of the above from decreasing due to the infiltration of the lubricating oil, and prevent the pressure inside the pneumatic chamber from becoming unstable.

By the way, the seal member 16 ₁ moves up and down relative to the piston 18 due to contact resistance and minute fluctuations in the pressure of the pneumatic chamber 15 during sliding movement of the piston 18 in the sliding hole 13. , Sealing member 16 ₁
Is repeatedly compressed against the piston 18.

Therefore, the seal member 16 ₂ as in the second embodiment shown in FIG. 4 may be used to avoid the deterioration of the seal function of the seal member 16 ₂ due to the repeated compression load.

The seal member 16 ₂ has a cylindrical base portion 16 _2a for elastically fitting the small diameter portion 19 of the piston 18.
When, which comprises a first lip 16 _2b and the second lip portion 16 _2c projecting from the base portion 16 _2a has a substantially V-shaped cross section open toward the inner surface of the slide hole 13 to the side , and the sealing member 1 so as to reinforce the connecting portion between the base portion 16 _2a of the base 16 _2a and both lip 16 _2b, 16 _2c
The reinforcing member 21 is embedded in 6 ₂ . Moreover, piston 1
A distance L between the reinforcing member 21 and the piston 18 along the axial direction of 8 is set to be larger than that of the seal member 16 ₁ of the first embodiment.

By doing so, a portion of the seal member 16 ₂ between the reinforcing member 21 and the piston 18 of the base portion 16 _2a can have a cushioning function, reduce the compressive load, and avoid deterioration of the seal function. be able to.

The seal member 1 of the third embodiment shown in FIG.
Even if 6 ₃ is used, deterioration of the sealing function due to the compressive load can be avoided. That is, the seal member 16 ₃ has a cylindrical base portion 16 _3a and a first lip portion that has a substantially V-shaped cross-sectional shape that opens toward the inner surface of the sliding hole 13 and that projects laterally from the base portion 16 _3a. 16 _3b and the second lip portion 16 _3c , and the base portion 16 _3a and both lip portions 16 _3b ,
The reinforcing member 21 ′ embedded in the seal member 16 ₃ so as to reinforce the connecting portion of 16 _{3c with} the base portion 16 _3a directly contacts the piston 18.

[0029] avoiding According to the third embodiment, by receiving a compressive load by the reinforcing member 21 'made of metal, to reduce the load acting on the seal member 16 ₃ a sealing function deterioration of the sealing member 16 ₃ You can

FIGS. 6 and 7 show a fourth embodiment of the present invention, in which the seal member 16 ₄ fitted on the outer surface of the piston 18 so as to be slidably contacted with the inner surface of the sliding hole 13 has a cylindrical shape. Of the base 16 _4a and a first lip 16 _4b and a second lip 16 _4c having a substantially V-shaped cross-sectional shape that opens toward the inner surface of the sliding hole 13 and projecting laterally from the base 16 _4a. with the door, metallic reinforcing member 21 so as to reinforce the connecting portion between the base portion 16 _4a of the base 16 _4a and both the lip 16 _4b, 16 _4c 'are embedded in the sealing member 16 within _4. Moreover, a plurality of ribs 36 are radially provided between the base portion 16 _4a and the first lip portion 16 _4b of the seal member 16 ₄ .

According to the fourth embodiment, the seal member 16
The rigidity of ₄ can be improved by the plurality of ribs 36,
As a result, the durability and reliability of the seal member 16 ₄ can be improved.

FIG. 8 shows a fifth embodiment of the present invention, in which a seal member 16 ₃ fitted to the piston 18 is slidable between the first lip portion 16 _3b and the second lip portion 16 _3c. A ring-shaped synthetic resin guide ring 37, which is in sliding contact with the inner surface of the moving hole 13, is fitted.

According to the fifth embodiment, when the piston 18 slides in the sliding hole 13, the seal member 16 ₃ moves vertically relative to the piston 18 due to a slight change in contact resistance and pressure in the pneumatic chamber 15. It is possible to suppress movement and stabilize the sealing function of the seal member 16 ₃ .

In the above embodiment, the lifter 14 is attached to the sliding hole 1
Although it is slidably fitted to the sleeve 3, a portion for guiding the lifter 14 may be provided above the sleeve 12.

The present invention is also applicable to a valve operating device for an exhaust valve. Further, the present invention can be applied to a valve operating device in which the power from the cam is applied to the lifter via a rocker arm as a driving member instead of directly sliding the cam onto the lifter.

[0036]

As described above, according to the present invention, the seal member is provided with the two lip portions inclined in the opening direction toward the inner surface of the sliding hole. It is possible to reliably prevent the leakage of the air pressure, and surely prevent the inflow of the lubricating oil into the air pressure chamber by the other lip portion to stabilize the air pressure in the air pressure chamber.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a valve gear according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of part 2 of FIG.

FIG. 3 is an enlarged view of part 3 of FIG.

FIG. 4 is a sectional view corresponding to FIG. 2 of a second embodiment of the present invention.

FIG. 5 is a sectional view corresponding to FIG. 2 of the third embodiment of the present invention.

FIG. 6 is a sectional view corresponding to FIG. 2 of a fourth embodiment of the present invention.

7 is a cross-sectional view taken along line 7-7 of FIG.

FIG. 8 is a sectional view of a fifth embodiment of the present invention, corresponding to FIG.

[Explanation of symbols]

1 engine body 8 engine as the intake valve valve 8 _a valve shaft portion 8 _b the valve body portion 12 the sleeve 13 sliding hole 14 ₄ lifter 15 pneumatic chamber 16 ₁ to 16 as a driving member seal member 16 _1b ~ 16 _4b lip 16 _{1c to} 16 _4c Lip 18 Piston

Claims (1)

[Claims] 1. A valve body portion (8 _b ) at the tip of _a valve shaft portion (8 _a ).
Openably is supported on the engine valve are thus provided (8) the engine body (1), the valve shaft portion (8 _a) rear driving member (1
4) is abutted, and the sleeve (12) fixed to the engine body (1) is provided with a bottomed sliding hole (13) to apply air pressure for urging the engine valve (8) in the valve closing direction. A piston (18), which is formed between the sliding chamber (13) and the bottom of the sliding hole (13) to form a generated air pressure chamber (15), is slidably fitted into the sliding hole (13).
Fixed sleeve (12) the valve stem which is plunged into the fluid tightly and movably penetrating to the slide hole (13) in the (8 _a), the outer surface of the piston (18) sliding hole (13 ) An annular seal member (16 ₁ , 16 ₂ , 16 ₃ , slidingly contacting the inner surface)
In the valve operating system of the internal combustion engine in which the sealing member (16 ₄ ) is fitted, the sealing members (16 _{1 to} 16 ₄ ) have two lip portions (1) inclined in a direction of opening toward the inner surface of the sliding hole (13).
6 _1b , 16 _1c ; 16 _2b , 16 _2c ; 16 _3b , 16 _3c ; 16
_4b , 16 _4c ) are provided.