WO2016111150A1 - Valve stem seal - Google Patents

Valve stem seal Download PDF

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Publication number
WO2016111150A1
WO2016111150A1 PCT/JP2015/085617 JP2015085617W WO2016111150A1 WO 2016111150 A1 WO2016111150 A1 WO 2016111150A1 JP 2015085617 W JP2015085617 W JP 2015085617W WO 2016111150 A1 WO2016111150 A1 WO 2016111150A1
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WO
WIPO (PCT)
Prior art keywords
valve stem
back pressure
lip
peripheral surface
valve
Prior art date
Application number
PCT/JP2015/085617
Other languages
French (fr)
Japanese (ja)
Inventor
陽紀 岩井
Original Assignee
Nok株式会社
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Filing date
Publication date
Application filed by Nok株式会社 filed Critical Nok株式会社
Priority to JP2016533221A priority Critical patent/JPWO2016111150A1/en
Publication of WO2016111150A1 publication Critical patent/WO2016111150A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/16—Sealings between relatively-moving surfaces
    • F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
    • F16J15/3204—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with at least one lip

Definitions

  • the present invention relates to a valve stem seal that seals between, for example, a valve stem of an intake / exhaust valve of an engine and a valve stem guide that supports the valve stem so as to be axially movable.
  • FIG. 5 shows an engine exhaust valve provided with a valve stem seal
  • FIG. 6 shows a conventional valve stem seal
  • reference numeral 101 denotes an engine cylinder head
  • 102 denotes an exhaust port formed in the cylinder head 101
  • 103 denotes an umbrella-type valve that opens and closes between the exhaust port 102 and the combustion chamber
  • 104 extends from the valve 103.
  • a valve stem 105 includes a valve guide 104 through which the valve stem 104 is inserted.
  • the valve stem 104 supports the valve stem 104 so as to be axially movable.
  • a spring 106 biases the valve 103 in the valve closing direction via the valve stem 104.
  • a valve stem seal 110 is mounted on the upper part of the valve guide 105, which is located on the outer peripheral side of the upper part of the valve guide 105 and is intended for sealing engine oil in an oil chamber 109 formed in the cylinder head 101.
  • the valve stem seal 110 has a cylindrical base 111 that is closely fitted to the upper outer peripheral surface of the valve guide 105, and extends from the upper end thereof so as to be slidably in contact with the outer peripheral surface of the valve stem 104.
  • Main lip 112 a reinforcing ring 113 that reinforces the cylindrical base 111, and a garter spring 114 that is attached to the outer periphery of the main lip 112 with a circumferential tension applied thereto.
  • the exhaust gas pressure at the exhaust port 102 rises, and this exhaust gas pressure passes through the gap ⁇ between the valve stem 104 and the valve guide 105 to the inner peripheral surface of the main lip 112 of the valve stem seal 110.
  • the main lip 112 is deformed and opened from the outer peripheral surface of the valve stem 104, and the flow rate of engine oil passing from the oil chamber 109 to the gap ⁇ side between the valve stem 104 and the valve guide 105 is reduced. May change significantly. Therefore, the valve stem seal 110 used under such conditions is provided with a back pressure lip 115 for preventing the back pressure from being applied to the inner peripheral surface of the main lip 112 (for example, the following patent document). 1).
  • the present invention has been made in view of the above points, and its technical problem is to suppress the increase in sliding resistance against the outer peripheral surface of the valve stem due to back pressure, thereby improving the operability of the valve stem. It is an object of the present invention to provide a valve stem seal that can maintain the above in a satisfactory manner.
  • the valve stem seal according to the present invention is reinforced by a reinforcing ring and is attached to the outer periphery of the valve guide, and is located closer to the oil chamber than the valve guide and from the base to the end of the reinforcing ring on the oil chamber side
  • a main lip extending from the inner diameter side of the neck portion toward the oil chamber side and slidably contacting the outer peripheral surface of the valve stem inserted through the valve guide;
  • a back pressure lip extending from the inner diameter side toward the valve guide side, the bending rigidity of the neck portion being smaller than the bending rigidity from the back pressure lip to the waist portion of the main lip, the back pressure lip being the valve guide Is slidably contacted with the outer peripheral surface of the valve stem by back pressure generated in the space between the back pressure lip and non-contact with the outer peripheral surface of the valve stem when the back pressure is not applied. It is characterized in that (claim 1).
  • the main lip when no back pressure is applied, the main lip slidably contacts the outer peripheral surface of the valve stem to limit oil leakage from the oil chamber to the valve guide side. Since it is not in contact with the outer peripheral surface of the valve stem, the sliding resistance with the valve stem can be kept low.
  • the back pressure lip When back pressure is generated in the space between the valve guide and the back pressure lip, the back pressure lip is slidably contacted with the outer peripheral surface of the valve stem by the back pressure acting on the outer peripheral surface. To limit the oil leakage from the oil chamber to the valve guide side.
  • the bending rigidity of the neck is smaller than the bending rigidity from the back pressure lip to the waist of the main lip, when the back pressure lip is displaced in the contact direction with the outer peripheral surface of the valve stem, the main lip is Displacement in a direction away from the outer peripheral surface of the valve stem suppresses an increase in sliding resistance.
  • the present invention may further employ the following means as means for effectively solving the technical problems described above. That is, in the valve stem seal having the above structure (Claim 1), when the back pressure lip is slidably contacted with the outer peripheral surface of the valve stem by the back pressure, the inner peripheral surface of the back pressure lip is the oil chamber side. The angle formed with the outer peripheral surface of the valve stem is smaller than the angle formed between the inner peripheral surface of the back pressure lip on the valve guide side and the outer peripheral surface of the valve stem (Claim 2).
  • the angle formed by the oil chamber side inner peripheral surface of the back pressure lip with the outer peripheral surface of the valve stem is smaller than the angle formed by the valve guide side inner peripheral surface of the back pressure lip with the outer peripheral surface of the valve stem. Therefore, in place of the main lip displaced in the direction away from the outer peripheral surface of the valve stem, the amount of leakage can be controlled so as to allow oil leakage from the oil chamber to the valve guide side appropriately.
  • valve stem seal of the present invention even if the back pressure lip slidably contacts the outer peripheral surface of the valve stem due to the back pressure, the increase in sliding resistance with respect to the outer peripheral surface of the valve stem is suppressed. It is possible to maintain good operability, improve fuel consumption, and control oil leakage from the oil chamber to the valve guide.
  • FIG. 6 is a half sectional view showing a conventional valve stem seal together with a valve guide and a valve stem in a state where a back pressure is applied.
  • reference numeral 104 is a valve stem extending from a valve for opening and closing an exhaust port (not shown) of the engine
  • reference numeral 105 is an engine.
  • the cylindrical valve guide is provided through the cylinder head and supports the valve stem 104 so as to be axially movable.
  • the lower end of the valve guide 105 opens to the exhaust port of the engine.
  • Engine oil is stored in an oil chamber 109 located on the side.
  • the valve stem seal 1 is reinforced by a reinforcing ring 15 made of metal and mounted on the outer peripheral surface of the valve guide 105, and the valve stem seal 1 is positioned on the oil chamber 109 side (above) from the valve guide 105 and extends from the cylindrical base 11.
  • a neck portion 12 extending toward the inner diameter side of the inward flange portion 15a bent at the upper end (the end portion on the oil chamber 109 side) of the reinforcing ring 15, and from the inner diameter side of the neck portion 12 toward the oil chamber 109 side (upward).
  • the cylindrical base portion 11, the neck portion 12, the main lip 13, and the back pressure lip 14 are continuous with each other, and are integrally formed on the reinforcing ring 15 with a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity). Is.
  • the cylindrical base portion 11 corresponds to the base portion described in claim 1.
  • the cylindrical base portion 11 is mounted in a state where the inner peripheral surface is in close contact with the upper outer peripheral surface of the valve guide 105 with an appropriate crushing margin, and is integrally vulcanized and bonded to the inner peripheral surface of the reinforcing ring 15. ing.
  • the neck portion 12 continuously extending from the upper end of the cylindrical base portion 11 toward the inner diameter side is integrally vulcanized and bonded to the inner diameter end of the inward flange portion 16 a at the upper end of the reinforcing ring 15.
  • the main lip 13 extends in the shape of a conical cylinder having a small diameter upward from the inner diameter side of the neck portion 12, and is a springless lip type, that is, a seal lip not fitted with a garter spring 114 as shown in FIG.
  • a lip tip 13 a formed on the inner periphery near the upper end is slidably in contact with the outer peripheral surface 104 a of the valve stem 104 on the upper side of the valve guide 105.
  • a plurality of support protrusions are provided on the inner peripheral surface of the axially intermediate portion of the main lip 13 in order to improve the following performance of the main lip 13 against the eccentricity of the valve stem 104 and prevent the main lip 13 from sticking to the solid surface.
  • 13b is formed in the circumferential direction equal distribution.
  • the back pressure lip 14 extends in the shape of a conical cylinder having a smaller diameter from the inner diameter side of the neck portion 12, and the lip tip 14 a extends between the valve stem 104 and the valve guide 105 from the exhaust port below the valve guide 105.
  • the valve stem 104 In a normal state in which the back pressure due to the exhaust gas pressure is not applied through the gap ⁇ , the valve stem 104 is not in contact with the outer peripheral surface 104a through a slight clearance.
  • the exhaust gas when high exhaust gas pressure is introduced into the space S between the valve guide 105 and the back pressure lip 14 through the gap ⁇ between the valve stem 104 and the valve guide 105, the exhaust gas further flows from the space S into the lip tip 14a.
  • the exhaust gas pressure in the outer circumferential space S becomes higher than the inner circumferential space of the back pressure lip 14, and the back pressure P (see FIG. 2) due to the differential pressure is increased.
  • the clearance between the outer peripheral surface 104a of the valve stem 104 and the lip tip 14a is set to an appropriate size.
  • the back pressure lip 14 is slidable on the outer peripheral surface 104a of the valve stem 104 as shown in FIG. 2 when the back pressure P generated by introducing the exhaust gas pressure into the space S is loaded from the outer periphery. It comes to be in contact.
  • the main lip 13 has an oil chamber extending upward (from the oil chamber 109 side) from the lip tip 13a in a state where the lip tip 13a is in contact with the valve stem outer peripheral surface 104a.
  • the angle ⁇ A formed by the side inner peripheral surface 13d with the valve stem outer peripheral surface 104a is the angle ⁇ B formed by the valve guide side inner peripheral surface 13e extending downward from the lip tip 13a (valve guide 105 side) with the valve stem outer peripheral surface 104a. It is formed to be smaller.
  • the back pressure lip 14 has an oil chamber extending upward (from the oil chamber 109 side) from the lip tip 14a in a state where the lip tip 14a is in contact with the valve stem outer peripheral surface 104a.
  • the angle ⁇ C formed by the side inner peripheral surface 14c with the valve stem outer peripheral surface 104a is the angle ⁇ D formed by the valve guide side inner peripheral surface 14d extending downward from the lip tip 14a (valve guide 105 side) with the valve stem outer peripheral surface 104a. It is formed to be smaller.
  • the back pressure lip 14 has a shape in which the thickness in the direction orthogonal to the extending direction gradually increases from the lip tip 14a side toward the root heel 14b side, also, neck 12 has its axial thickness t 12 is the direction of the meat to be perpendicular to the extending direction of the wall thickness (the main lip 13 of the waist 13c of the wall thickness t 14 and the main lip 13 of the heel 14b of the back pressure lip 14 thick) has a smaller becomes so constricted shape from t 13, which bending stiffness of the neck portion 12 by is set from the back pressure lip 14 smaller than the bending rigidity of the over the waist 13c of the main lip 13. Therefore, when the back pressure lip 14 is displaced from the normal state shown in FIG. 1 or FIG. 3A to the contact state shown in FIG. 2 or FIG. The displacement force in the direction away from the outer peripheral surface 104a of the valve stem 104 is received.
  • the back pressure due to the exhaust gas pressure introduced into the space S from the exhaust port below the valve guide 105 through the gap ⁇ between the valve stem 104 and the valve guide 105 is loaded.
  • the main lip 13 has the lip tip 13a and the support protrusion 13b slidably in contact with the outer peripheral surface 104a of the valve stem 104 above the valve guide 105.
  • the engine oil in the chamber 109 is appropriately restricted from flowing into the gap ⁇ between the outer peripheral surface 104a of the valve stem 104 and the inner peripheral surface of the valve guide 105.
  • the back pressure lip 14 is normally not in contact with the outer peripheral surface 104 a of the valve stem 104, and only the main lip 13 is in contact with the outer peripheral surface 104 a of the valve stem 104.
  • the sliding resistance against movement is kept small.
  • the exhaust gas pressure at the exhaust port instantaneously rises, and this high exhaust gas pressure passes through the gap ⁇ between the valve stem 104 and the valve guide 105, and the space between the valve guide 105 and the back pressure lip 14.
  • the exhaust gas pressure at the outer periphery (space S) becomes higher than the inner periphery of the back pressure lip 14, and the differential pressure becomes the back pressure P as shown in FIG. Act on the surface.
  • the back pressure lip 14 receives the back pressure P and is displaced so that the lip tip 14 a is slidably in contact with the outer peripheral surface 104 a of the valve stem 104.
  • the displacement of the back pressure lip 14 causes the valve lip 104 to be displaced by the moment with the neck 12 as a fulcrum. Acts to move away from the outer peripheral surface 104a.
  • a part of the back pressure P acts so as to bend and deform the portion from the heel 14 b of the back pressure lip 14 to the neck portion 12 upward, so that the main lip 13 is the outer peripheral surface of the valve stem 104 with the neck portion 12 as a fulcrum.
  • the displacement in the direction away from 104a is promoted. Therefore, since only the back pressure lip 14 is in contact with the outer peripheral surface 104a of the valve stem 104, the sliding resistance against the reciprocating motion of the valve stem 104 can be kept small.
  • the back pressure lip 14 has an angle of ⁇ C ⁇ D with the outer peripheral surface 104a of the valve stem 104 on both upper and lower sides of the lip tip 14a.
  • An appropriate amount of engine oil is allowed to flow into the gap ⁇ . Therefore, in place of the main lip 13 displaced in the direction away from the outer peripheral surface 104a of the valve stem 104, lubrication between the valve stem 104 and the valve guide 105 is achieved, and engine oil from the gap ⁇ to the combustion chamber side is obtained.
  • the function of preventing generation of white smoke due to an increase in leakage and an increase in consumption of engine oil can be assumed.
  • the back pressure lip 14 does not displace toward the inner peripheral side of the main lip 13 due to the back pressure P.
  • An increase in sliding resistance and an increase in wear between the lip 14 and the outer peripheral surface 104a of the valve stem 104 are also suppressed.
  • the main lip 13 is a springless lip type not fitted with a garter spring, but the back pressure lip 14 is in a contact state from a non-contact state with the outer peripheral surface 104a of the valve stem 104. If it is possible to move away from the outer peripheral surface 104a of the valve stem 104 by a moment with the neck portion 12 as a bending start point, a specification with a garter spring attached may be employed.
  • the angle ⁇ C ′ formed by the oil chamber side inner peripheral surface 14c of the back pressure lip 14 with respect to the virtual cylindrical surface 104a ′ concentric with the valve stem shown in FIG. 4 is 5 to 0.40 mm.
  • an angle ⁇ D ′ formed by the valve guide side inner peripheral surface 14d with respect to the virtual cylindrical surface 104a ′ is 5 to 50 °
  • the lip tip 14a is placed on the outer peripheral surface 104a of the valve stem 104 by the load of the back pressure P.
  • the angle ⁇ C formed by the oil chamber side inner peripheral surface 14c with respect to the outer peripheral surface 104a is 5 to 50 °
  • the angle ⁇ D formed by the valve guide inner peripheral surface 14d is 5 to 50 ° ( However, ⁇ C ⁇ D ) is preferable.
  • the lip tip 14a of the back pressure lip 14 and the valve stem 104 in a normal state in which the back pressure P is not loaded.
  • the clearance with the outer peripheral surface 104a is 0.20 mm, and the angle ⁇ C ′ formed by the oil chamber side inner peripheral surface 14c of the back pressure lip 14 with respect to the virtual cylindrical surface 104a ′ concentric with the valve stem shown in FIG.
  • the lip tip 14a is brought into contact with the outer peripheral surface 104a of the valve stem 104 by the load of the back pressure P.
  • the angle ⁇ C formed by the oil chamber side inner peripheral surface 14c with respect to the outer peripheral surface 104a is preferably 20 °
  • the angle ⁇ D formed by the valve guide side inner peripheral surface 14d is preferably 40 °.
  • Valve stem seal 11 Cylindrical base (base) 12 Neck 13 Main lip 13a Lip tip 14 Back pressure lip 14a Lip tip 15 Reinforcement ring 104 Valve stem 105 Valve guide 109 Oil chamber

Abstract

In order to prevent an increase in the sliding resistance with respect to an outer circumferential surface of a valve stem (104) due to back pressure and to improve the operability of the valve stem (104), this valve stem seal is provided with: a base part (11) reinforced by a reinforcing ring (15) and mounted on the outer circumference of a valve guide (105); a neck part (12) positioned more adjacent to the side of an oil chamber (109) than the valve guide (105) and extending from the base part (11) toward the inner diameter side of an end section of the oil chamber (109) side of the reinforcing ring (15); a main lip (13) extending from the inner diameter side of the neck part (12) toward the oil chamber (109) side and slidably contacting the valve stem (104); and a back pressure lip (14) extending from the inner diameter side of the neck part (12) toward the valve guide (105) side, wherein the neck part (12) has a lower bending stiffness than the portion from the back pressure lip (14) to the waist section of the main lip (13), and the back pressure lip (14) slidably contacts the valve stem (104) by means of the back pressure and does not contact the valve stem (104) when there is no back pressure load.

Description

バルブステムシールValve stem seal
　本発明は、例えばエンジンの吸・排気バルブのバルブステムと、これを軸方向移動自在に支持するバルブステムガイドとの間を密封するバルブステムシールに関する。 The present invention relates to a valve stem seal that seals between, for example, a valve stem of an intake / exhaust valve of an engine and a valve stem guide that supports the valve stem so as to be axially movable.
　エンジンの吸・排気バルブのバルブステムと、これを軸方向移動自在に支持するバルブステムガイドとの間は、バルブステムシールによって密封されている。図５は、バルブステムシールを設けたエンジンの排気バルブ、図６は、従来のバルブステムシールを示すものである。 エ ン ジ ン The valve stem seal between the valve stem of the intake / exhaust valve of the engine and the valve stem guide that supports the valve stem so as to be axially movable is sealed. FIG. 5 shows an engine exhaust valve provided with a valve stem seal, and FIG. 6 shows a conventional valve stem seal.
　図５において、参照符号１０１はエンジンのシリンダヘッド、１０２はシリンダヘッド１０１に形成された排気ポート、１０３は排気ポート１０２と燃焼室との間を開閉する傘型のバルブ、１０４はバルブ１０３から延びるバルブステム、１０５はバルブステム１０４が挿通され、このバルブステム１０４を軸方向移動自在に支持するバルブガイド、１０６はバルブステム１０４を介してバルブ１０３を閉弁方向へ付勢するスプリング、１０７はバルブステム１０４の上端に設けられたリフタ１０８に接触されると共に、カムシャフト１０７ａによって１回転する度に、スプリング１０６を圧縮させながらリフタ１０８及びバルブステム１０４を介してバルブ１０３を押し下げて開弁させるカムである。バルブガイド１０５の上部には、バルブガイド１０５の上部の外周側に位置してシリンダヘッド１０１に形成された油室１０９内のエンジンオイルをシール対象とするバルブステムシール１１０が装着されている。 In FIG. 5, reference numeral 101 denotes an engine cylinder head, 102 denotes an exhaust port formed in the cylinder head 101, 103 denotes an umbrella-type valve that opens and closes between the exhaust port 102 and the combustion chamber, and 104 extends from the valve 103. A valve stem 105 includes a valve guide 104 through which the valve stem 104 is inserted. The valve stem 104 supports the valve stem 104 so as to be axially movable. A spring 106 biases the valve 103 in the valve closing direction via the valve stem 104. A cam that contacts the lifter 108 provided at the upper end of the stem 104 and opens the valve 103 by pushing down the valve 103 via the lifter 108 and the valve stem 104 while compressing the spring 106 every time the camshaft 107a makes one rotation. It is. A valve stem seal 110 is mounted on the upper part of the valve guide 105, which is located on the outer peripheral side of the upper part of the valve guide 105 and is intended for sealing engine oil in an oil chamber 109 formed in the cylinder head 101.
　バルブステムシール１１０は、詳しくは図６に示すように、バルブガイド１０５の上部外周面に密嵌される筒状基部１１１と、その上端から延び、バルブステム１０４の外周面に摺動可能に接触されるメインリップ１１２と、筒状基部１１１を補強する補強環１１３と、メインリップ１１２の外周に円周方向の張力を与えられた状態で装着されたガータスプリング１１４を備え、油室１０９内のエンジンオイルが、バルブステム１０４の外周面とバルブガイド１０５の内周面との間の隙間δへ流入するのをある程度許容することによって、バルブステム１０４とバルブガイド１０５との間の潤滑を図ると共に、隙間δから燃焼室側へのエンジンオイルの漏れ量増大による白煙の発生やエンジンオイル消費量の増大などを防止するために、エンジンオイルの漏れ量を適切に制御する機能を担っている。 As shown in detail in FIG. 6, the valve stem seal 110 has a cylindrical base 111 that is closely fitted to the upper outer peripheral surface of the valve guide 105, and extends from the upper end thereof so as to be slidably in contact with the outer peripheral surface of the valve stem 104. Main lip 112, a reinforcing ring 113 that reinforces the cylindrical base 111, and a garter spring 114 that is attached to the outer periphery of the main lip 112 with a circumferential tension applied thereto. By allowing engine oil to flow into the gap δ between the outer peripheral surface of the valve stem 104 and the inner peripheral surface of the valve guide 105 to some extent, lubrication between the valve stem 104 and the valve guide 105 is achieved. In order to prevent the generation of white smoke and the increase in engine oil consumption due to an increase in the amount of engine oil leaking from the gap δ into the combustion chamber, Has a function to properly control the amount of gin oil leakage.
　また、例えばエンジンの始動時に、排気ポート１０２における排ガス圧力が上昇して、この排ガス圧力がバルブステム１０４とバルブガイド１０５の間の隙間δを通じてバルブステムシール１１０のメインリップ１１２の内周面に背圧として負荷された場合、メインリップ１１２が拡径変形されてバルブステム１０４の外周面から開いてしまい、油室１０９からバルブステム１０４とバルブガイド１０５の隙間δ側へ通過するエンジンオイルの流量が大きく変化するおそれがある。したがって、このような条件で使用されるバルブステムシール１１０には、メインリップ１１２の内周面に背圧が負荷されるのを防止するための背圧リップ１１５が設けられる（例えば下記の特許文献１参照）。 Further, for example, when the engine is started, the exhaust gas pressure at the exhaust port 102 rises, and this exhaust gas pressure passes through the gap δ between the valve stem 104 and the valve guide 105 to the inner peripheral surface of the main lip 112 of the valve stem seal 110. When the pressure is applied, the main lip 112 is deformed and opened from the outer peripheral surface of the valve stem 104, and the flow rate of engine oil passing from the oil chamber 109 to the gap δ side between the valve stem 104 and the valve guide 105 is reduced. May change significantly. Therefore, the valve stem seal 110 used under such conditions is provided with a back pressure lip 115 for preventing the back pressure from being applied to the inner peripheral surface of the main lip 112 (for example, the following patent document). 1).
特開平１０－２０５６２３号公報JP-A-10-205623
　しかしながら、バルブステムシール１１０に背圧リップ１１５を設けた場合は、バルブステム１０４とバルブガイド１０５の間の隙間δを通じて導入される背圧Ｐは、背圧リップ１１５の外周面に作用し、このためバルブステム１０４の外周面に対する背圧リップ１１５の締め付け力が増大するので、バルブステム１０４の往復動に対する摺動抵抗が大きくなって、燃費の向上を阻害するおそれがある。 However, when the back pressure lip 115 is provided on the valve stem seal 110, the back pressure P introduced through the gap δ between the valve stem 104 and the valve guide 105 acts on the outer peripheral surface of the back pressure lip 115, and this Therefore, since the tightening force of the back pressure lip 115 with respect to the outer peripheral surface of the valve stem 104 increases, the sliding resistance with respect to the reciprocating motion of the valve stem 104 increases, which may hinder improvement in fuel consumption.
　本発明は、以上のような点に鑑みてなされたものであって、その技術的課題は、背圧によるバルブステムの外周面に対する摺動抵抗の増大を抑制することによって、バルブステムの作動性を良好に維持可能なバルブステムシールを提供することにある。 The present invention has been made in view of the above points, and its technical problem is to suppress the increase in sliding resistance against the outer peripheral surface of the valve stem due to back pressure, thereby improving the operability of the valve stem. It is an object of the present invention to provide a valve stem seal that can maintain the above in a satisfactory manner.
　本発明は、上述した技術的課題を有効に解決するための手段として、以下の手段を採用した。すなわち本発明に係るバルブステムシールは、補強環によって補強され、バルブガイドの外周に装着される基部と、前記バルブガイドより油室側に位置し前記基部から前記補強環の油室側の端部の内径側へ延びる首部と、この首部の内径側から前記油室側へ向けて延び、前記バルブガイドに挿通されたバルブステムの外周面に摺動可能に接触されるメインリップと、前記首部の内径側から前記バルブガイド側へ向けて延びる背圧リップと、を備え、前記首部の曲げ剛性が前記背圧リップから前記メインリップの腰部にかけての曲げ剛性より小さく、前記背圧リップは前記バルブガイドと背圧リップの間の空間に生じる背圧によって前記バルブステムの外周面に摺動可能に接触され、前記背圧の無負荷時には前記バルブステムの外周面と非接触であることを特徴とするものである（請求項１）。 The present invention employs the following means as means for effectively solving the technical problems described above. That is, the valve stem seal according to the present invention is reinforced by a reinforcing ring and is attached to the outer periphery of the valve guide, and is located closer to the oil chamber than the valve guide and from the base to the end of the reinforcing ring on the oil chamber side A main lip extending from the inner diameter side of the neck portion toward the oil chamber side and slidably contacting the outer peripheral surface of the valve stem inserted through the valve guide; A back pressure lip extending from the inner diameter side toward the valve guide side, the bending rigidity of the neck portion being smaller than the bending rigidity from the back pressure lip to the waist portion of the main lip, the back pressure lip being the valve guide Is slidably contacted with the outer peripheral surface of the valve stem by back pressure generated in the space between the back pressure lip and non-contact with the outer peripheral surface of the valve stem when the back pressure is not applied. It is characterized in that (claim 1).
　上記構成において、背圧の無負荷時には、メインリップがバルブステムの外周面に摺動可能に接触することによって、油室からバルブガイド側へのオイルの漏れを制限しており、背圧リップがバルブステムの外周面と非接触であるためバルブステムとの摺動抵抗が低く抑えられる。また、バルブガイドと背圧リップの間の空間に背圧が生じた場合には、背圧リップが、その外周面に作用する背圧によって先端がバルブステムの外周面に摺動可能に接触するように変位して油室からバルブガイド側へのオイルの漏れを制限する。そして首部の曲げ剛性が背圧リップからメインリップの腰部にかけての曲げ剛性より小さいため、背圧リップがバルブステムの外周面との接触方向へ変位すると、首部を支点とするモーメントによって、メインリップはバルブステムの外周面から離間する方向へ変位し、摺動抵抗の増大が抑えられる。 In the above configuration, when no back pressure is applied, the main lip slidably contacts the outer peripheral surface of the valve stem to limit oil leakage from the oil chamber to the valve guide side. Since it is not in contact with the outer peripheral surface of the valve stem, the sliding resistance with the valve stem can be kept low. When back pressure is generated in the space between the valve guide and the back pressure lip, the back pressure lip is slidably contacted with the outer peripheral surface of the valve stem by the back pressure acting on the outer peripheral surface. To limit the oil leakage from the oil chamber to the valve guide side. And since the bending rigidity of the neck is smaller than the bending rigidity from the back pressure lip to the waist of the main lip, when the back pressure lip is displaced in the contact direction with the outer peripheral surface of the valve stem, the main lip is Displacement in a direction away from the outer peripheral surface of the valve stem suppresses an increase in sliding resistance.
　また、本発明は上述した技術的課題を有効に解決するための手段として、更に以下の手段を採用してもよい。すなわち上記構成のバルブステムシール（請求項１）において、背圧リップが背圧によってバルブステムの外周面に摺動可能に接触された状態では、この背圧リップの油室側内周面が前記バルブステムの外周面となす角度が、この背圧リップのバルブガイド側内周面が前記バルブステムの外周面となす角度より小さいことを特徴とするものである（請求項２）。 Further, the present invention may further employ the following means as means for effectively solving the technical problems described above. That is, in the valve stem seal having the above structure (Claim 1), when the back pressure lip is slidably contacted with the outer peripheral surface of the valve stem by the back pressure, the inner peripheral surface of the back pressure lip is the oil chamber side. The angle formed with the outer peripheral surface of the valve stem is smaller than the angle formed between the inner peripheral surface of the back pressure lip on the valve guide side and the outer peripheral surface of the valve stem (Claim 2).
　上記構成において、背圧リップの油室側内周面が前記バルブステムの外周面となす角度を、背圧リップのバルブガイド側内周面が前記バルブステムの外周面となす角度より小さくなるようにしたため、バルブステムの外周面から離間する方向へ変位したメインリップに代わって、油室からバルブガイド側へのオイルの漏れを適切に許容するように、漏れ量を制御することができる。 In the above configuration, the angle formed by the oil chamber side inner peripheral surface of the back pressure lip with the outer peripheral surface of the valve stem is smaller than the angle formed by the valve guide side inner peripheral surface of the back pressure lip with the outer peripheral surface of the valve stem. Therefore, in place of the main lip displaced in the direction away from the outer peripheral surface of the valve stem, the amount of leakage can be controlled so as to allow oil leakage from the oil chamber to the valve guide side appropriately.
　本発明に係るバルブステムシールによれば、背圧によって背圧リップがバルブステムの外周面に摺動可能に接触してもバルブステムの外周面に対する摺動抵抗の増大を抑制してバルブステムの作動性を良好に維持可能であると共に燃費を向上させ、かつ油室からバルブガイド側へのオイルの漏れを制御することができる。 According to the valve stem seal of the present invention, even if the back pressure lip slidably contacts the outer peripheral surface of the valve stem due to the back pressure, the increase in sliding resistance with respect to the outer peripheral surface of the valve stem is suppressed. It is possible to maintain good operability, improve fuel consumption, and control oil leakage from the oil chamber to the valve guide.
本発明に係るバルブステムシールを、バルブガイド及びバルブステムと共に示す、無負荷状態の半断面図である。It is a half section view of a no load state showing a valve stem seal concerning the present invention with a valve guide and a valve stem. 本発明に係るバルブステムシールを、バルブガイド及びバルブステムと共に示す、背圧が負荷された状態の半断面図である。It is a half section view in the state where back pressure was loaded showing a valve stem seal concerning the present invention with a valve guide and a valve stem. 本発明に係るバルブステムシールにおいてバルブステムの外周面に対する接触角度を説明するための図である。It is a figure for demonstrating the contact angle with respect to the outer peripheral surface of a valve stem in the valve stem seal which concerns on this invention. 本発明に係るバルブステムシールの各部の肉厚を示す要部断面図である。It is principal part sectional drawing which shows the thickness of each part of the valve stem seal which concerns on this invention. バルブステムシールを設けたエンジンの排気バルブを示す断面図である。It is sectional drawing which shows the exhaust valve of the engine which provided the valve stem seal. 従来のバルブステムシールを、バルブガイド及びバルブステムと共に示す、背圧が負荷された状態の半断面図である。FIG. 6 is a half sectional view showing a conventional valve stem seal together with a valve guide and a valve stem in a state where a back pressure is applied.
　以下、本発明に係るバルブステムシールの好ましい実施の形態について、図面を参照しながら説明する。 Hereinafter, preferred embodiments of the valve stem seal according to the present invention will be described with reference to the drawings.
　図１において、バルブステムシール１以外の各部は先に説明した図６と同様であって、すなわち参照符号１０４はエンジンの不図示の排気ポートを開閉するバルブから延びるバルブステム、参照符号１０５はエンジンのシリンダヘッドを貫通して設けられ、バルブステム１０４を軸方向移動自在に支持する円筒状のバルブガイドで、バルブガイド１０５の下端はエンジンの排気ポートに開口しており、バルブガイド１０５の上部外周側に存在する油室１０９内にはエンジンオイルが貯留されている。 1, the parts other than the valve stem seal 1 are the same as those in FIG. 6 described above, that is, reference numeral 104 is a valve stem extending from a valve for opening and closing an exhaust port (not shown) of the engine, and reference numeral 105 is an engine. The cylindrical valve guide is provided through the cylinder head and supports the valve stem 104 so as to be axially movable. The lower end of the valve guide 105 opens to the exhaust port of the engine. Engine oil is stored in an oil chamber 109 located on the side.
　バルブステムシール１は、金属からなる補強環１５によって補強されバルブガイド１０５の外周面に装着される筒状基部１１と、バルブガイド１０５より油室１０９側（上方）に位置し筒状基部１１から補強環１５の上端（油室１０９側の端部）に屈曲形成された内向き鍔部１５ａの内径側へ延びる首部１２と、この首部１２の内径側から油室１０９側（上方）へ向けて延び、バルブガイド１０５に挿通されたバルブステム１０４の外周面１０４ａに摺動可能に接触されるメインリップ１３と、首部１２の内径側からバルブガイド１０５側（下方）へ向けて延びる背圧リップ１４と、を備える。筒状基部１１、首部１２、メインリップ１３、及び背圧リップ１４は互いに連続しており、ゴム状弾性材料（ゴム材料又はゴム状弾性を有する合成樹脂材料）で補強環１５に一体成形されたものである。なお、筒状基部１１は請求項１に記載された基部に相当するものである。 The valve stem seal 1 is reinforced by a reinforcing ring 15 made of metal and mounted on the outer peripheral surface of the valve guide 105, and the valve stem seal 1 is positioned on the oil chamber 109 side (above) from the valve guide 105 and extends from the cylindrical base 11. A neck portion 12 extending toward the inner diameter side of the inward flange portion 15a bent at the upper end (the end portion on the oil chamber 109 side) of the reinforcing ring 15, and from the inner diameter side of the neck portion 12 toward the oil chamber 109 side (upward). A main lip 13 that extends and slidably contacts the outer peripheral surface 104a of the valve stem 104 inserted through the valve guide 105, and a back pressure lip 14 that extends from the inner diameter side of the neck portion 12 toward the valve guide 105 side (downward). And comprising. The cylindrical base portion 11, the neck portion 12, the main lip 13, and the back pressure lip 14 are continuous with each other, and are integrally formed on the reinforcing ring 15 with a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity). Is. The cylindrical base portion 11 corresponds to the base portion described in claim 1.
　筒状基部１１は、内周面がバルブガイド１０５の上部外周面に適当なつぶし代をもって密接した状態で装着されるものであって、補強環１５の内周面に一体的に加硫接着されている。 The cylindrical base portion 11 is mounted in a state where the inner peripheral surface is in close contact with the upper outer peripheral surface of the valve guide 105 with an appropriate crushing margin, and is integrally vulcanized and bonded to the inner peripheral surface of the reinforcing ring 15. ing.
　筒状基部１１の上端から内径側へ連続して延びる首部１２は、補強環１５の上端の内向き鍔部１６ａの内径端に一体的に加硫接着されている。 The neck portion 12 continuously extending from the upper end of the cylindrical base portion 11 toward the inner diameter side is integrally vulcanized and bonded to the inner diameter end of the inward flange portion 16 a at the upper end of the reinforcing ring 15.
　メインリップ１３は、首部１２の内径側から上方へ向けて小径になる円錐筒状に延び、ばねなしリップ型、すなわち図６のようなガータスプリング１１４を装着しないシールリップであって、バルブガイド１０５の下方の排気ポートからバルブステム１０４とバルブガイド１０５の間の隙間δを通じてバルブガイド１０５と背圧リップ１４の間の空間Ｓへ導入される排ガス圧力による背圧が負荷されていない通常状態では、上端近傍の内周に形成されたリップ先端１３ａが、バルブガイド１０５の上側でバルブステム１０４の外周面１０４ａに摺動可能に接触されている。また、メインリップ１３の軸方向中間部の内周面には、バルブステム１０４の偏心等に対するメインリップ１３の追随性能を向上させると共にメインリップ１３のベタ当たりを防止するために、複数の支持突起１３ｂが円周方向等配状に形成されている。 The main lip 13 extends in the shape of a conical cylinder having a small diameter upward from the inner diameter side of the neck portion 12, and is a springless lip type, that is, a seal lip not fitted with a garter spring 114 as shown in FIG. In a normal state in which the back pressure due to the exhaust gas pressure introduced into the space S between the valve guide 105 and the back pressure lip 14 through the gap δ between the valve stem 104 and the valve guide 105 from the exhaust port below is not loaded, A lip tip 13 a formed on the inner periphery near the upper end is slidably in contact with the outer peripheral surface 104 a of the valve stem 104 on the upper side of the valve guide 105. In addition, a plurality of support protrusions are provided on the inner peripheral surface of the axially intermediate portion of the main lip 13 in order to improve the following performance of the main lip 13 against the eccentricity of the valve stem 104 and prevent the main lip 13 from sticking to the solid surface. 13b is formed in the circumferential direction equal distribution.
　背圧リップ１４は、首部１２の内径側から下方へ向けて小径になる円錐筒状に延び、そのリップ先端１４ａは、バルブガイド１０５の下方の排気ポートからバルブステム１０４とバルブガイド１０５の間の隙間δを通じて排ガス圧力による背圧が負荷されていない通常状態では、バルブステム１０４の外周面１０４ａに対してわずかなクリアランスを介して非接触状態にある。 The back pressure lip 14 extends in the shape of a conical cylinder having a smaller diameter from the inner diameter side of the neck portion 12, and the lip tip 14 a extends between the valve stem 104 and the valve guide 105 from the exhaust port below the valve guide 105. In a normal state in which the back pressure due to the exhaust gas pressure is not applied through the gap δ, the valve stem 104 is not in contact with the outer peripheral surface 104a through a slight clearance.
　また、高い排ガス圧力がバルブステム１０４とバルブガイド１０５の間の隙間δを通じてバルブガイド１０５と背圧リップ１４の間の空間Ｓに導入されたときに、排ガスが空間Ｓからさらにリップ先端１４ａの内周のクリアランスを通過しようとする過程で圧力損失を生じることによって、背圧リップ１４の内周空間よりも外周空間Ｓの排ガス圧力が高くなり、その差圧による背圧Ｐ（図２参照）を生じるように、バルブステム１０４の外周面１０４ａとリップ先端１４ａとの間のクリアランスは、適切な大きさに設定されている。そして背圧リップ１４は、排ガス圧力が空間Ｓに導入されることによって生じる背圧Ｐが外周から負荷されることによって、図２に示すように、バルブステム１０４の外周面１０４ａに摺動可能に接触されるようになっている。 Further, when high exhaust gas pressure is introduced into the space S between the valve guide 105 and the back pressure lip 14 through the gap δ between the valve stem 104 and the valve guide 105, the exhaust gas further flows from the space S into the lip tip 14a. By causing a pressure loss in the process of passing through the circumferential clearance, the exhaust gas pressure in the outer circumferential space S becomes higher than the inner circumferential space of the back pressure lip 14, and the back pressure P (see FIG. 2) due to the differential pressure is increased. As occurs, the clearance between the outer peripheral surface 104a of the valve stem 104 and the lip tip 14a is set to an appropriate size. The back pressure lip 14 is slidable on the outer peripheral surface 104a of the valve stem 104 as shown in FIG. 2 when the back pressure P generated by introducing the exhaust gas pressure into the space S is loaded from the outer periphery. It comes to be in contact.
　ここで、図３（Ａ）に示すように、メインリップ１３は、そのリップ先端１３ａがバルブステム外周面１０４ａに接触された状態において、リップ先端１３ａから上側（油室１０９側）へ延びる油室側内周面１３ｄがバルブステム外周面１０４ａとなす角度θＡが、リップ先端１３ａから下側（バルブガイド１０５側）へ延びるバルブガイド側内周面１３ｅがバルブステム外周面１０４ａとなす角度θＢより小さくなるように形成されている。 Here, as shown in FIG. 3A, the main lip 13 has an oil chamber extending upward (from the oil chamber 109 side) from the lip tip 13a in a state where the lip tip 13a is in contact with the valve stem outer peripheral surface 104a. The angle θ A formed by the side inner peripheral surface 13d with the valve stem outer peripheral surface 104a is the angle θ B formed by the valve guide side inner peripheral surface 13e extending downward from the lip tip 13a (valve guide 105 side) with the valve stem outer peripheral surface 104a. It is formed to be smaller.
　また、図３（Ｂ）に示すように、背圧リップ１４は、そのリップ先端１４ａがバルブステム外周面１０４ａに接触された状態において、リップ先端１４ａから上側（油室１０９側）へ延びる油室側内周面１４ｃがバルブステム外周面１０４ａとなす角度θＣが、リップ先端１４ａから下側（バルブガイド１０５側）へ延びるバルブガイド側内周面１４ｄがバルブステム外周面１０４ａとなす角度θＤより小さくなるように形成されている。 As shown in FIG. 3B, the back pressure lip 14 has an oil chamber extending upward (from the oil chamber 109 side) from the lip tip 14a in a state where the lip tip 14a is in contact with the valve stem outer peripheral surface 104a. The angle θ C formed by the side inner peripheral surface 14c with the valve stem outer peripheral surface 104a is the angle θ D formed by the valve guide side inner peripheral surface 14d extending downward from the lip tip 14a (valve guide 105 side) with the valve stem outer peripheral surface 104a. It is formed to be smaller.
　また、図４に示すように、背圧リップ１４は、その延長方向と直交する方向の肉厚がそのリップ先端１４ａ側から根元のヒール１４ｂ側へ向けて徐々に増大する形状となっており、また、首部１２は、その軸方向肉厚ｔ１２が、背圧リップ１４のヒール１４ｂの肉厚ｔ１４及びメインリップ１３の腰部１３ｃの肉厚（メインリップ１３の延長方向と直交する方向の肉厚）ｔ１３より小さくなるようにくびれた形状となっており、これによって首部１２の曲げ剛性は、背圧リップ１４からメインリップ１３の腰部１３ｃにかけての曲げ剛性より小さく設定されている。したがって背圧リップ１４が、図１又は図３（Ａ）に示す通常状態から図２又は図３（Ｂ）に示す接触状態へ変位すると、首部１２を曲げ起点とするモーメントによって、メインリップ１３が、バルブステム１０４の外周面１０４ａから離間する方向への変位力を受けるようになっている。 Further, as shown in FIG. 4, the back pressure lip 14 has a shape in which the thickness in the direction orthogonal to the extending direction gradually increases from the lip tip 14a side toward the root heel 14b side, also, neck 12 has its axial thickness t 12 is the direction of the meat to be perpendicular to the extending direction of the wall thickness (the main lip 13 of the waist 13c of the wall thickness t 14 and the main lip 13 of the heel 14b of the back pressure lip 14 thick) has a smaller becomes so constricted shape from t 13, which bending stiffness of the neck portion 12 by is set from the back pressure lip 14 smaller than the bending rigidity of the over the waist 13c of the main lip 13. Therefore, when the back pressure lip 14 is displaced from the normal state shown in FIG. 1 or FIG. 3A to the contact state shown in FIG. 2 or FIG. The displacement force in the direction away from the outer peripheral surface 104a of the valve stem 104 is received.
　以上のように構成された図示の実施の形態において、バルブガイド１０５の下方の排気ポートからバルブステム１０４とバルブガイド１０５の間の隙間δを通じて空間Ｓに導入される排ガス圧力による背圧が負荷されていない通常状態では、図１に示すように、メインリップ１３は、リップ先端１３ａ及び支持突起１３ｂがバルブガイド１０５の上側でバルブステム１０４の外周面１０４ａに摺動可能に接触しており、油室１０９内のエンジンオイルがバルブステム１０４の外周面１０４ａとバルブガイド１０５の内周面との間の隙間δへ流入するのを、適切に制限するものである。詳しくは図３（Ａ）に示すように、θＡ＜θＢとなっていることによって、隙間δへ適量のエンジンオイルが流入するのを許容しており、バルブステム１０４とバルブガイド１０５との間の潤滑を図ると共に、隙間δから燃焼室側へのエンジンオイルの漏れ量増大による白煙の発生やエンジンオイルの消費量の増大などを防止する機能を担っている。 In the illustrated embodiment configured as described above, the back pressure due to the exhaust gas pressure introduced into the space S from the exhaust port below the valve guide 105 through the gap δ between the valve stem 104 and the valve guide 105 is loaded. In the normal state, as shown in FIG. 1, the main lip 13 has the lip tip 13a and the support protrusion 13b slidably in contact with the outer peripheral surface 104a of the valve stem 104 above the valve guide 105. The engine oil in the chamber 109 is appropriately restricted from flowing into the gap δ between the outer peripheral surface 104a of the valve stem 104 and the inner peripheral surface of the valve guide 105. Specifically, as shown in FIG. 3A, since θ A <θ B , an appropriate amount of engine oil is allowed to flow into the gap δ, and the valve stem 104 and the valve guide 105 And the function of preventing the generation of white smoke due to an increase in the amount of engine oil leaked from the gap δ into the combustion chamber and the increase in the amount of consumption of engine oil.
　一方、背圧リップ１４は、バルブステム１０４の外周面１０４ａに対して通常非接触の状態にあり、メインリップ１３のみがバルブステム１０４の外周面１０４ａに接触しているため、バルブステム１０４の往復動に対する摺動抵抗が小さく抑えられる。 On the other hand, the back pressure lip 14 is normally not in contact with the outer peripheral surface 104 a of the valve stem 104, and only the main lip 13 is in contact with the outer peripheral surface 104 a of the valve stem 104. The sliding resistance against movement is kept small.
　また、例えばエンジンの始動時に、排気ポートにおける排ガス圧力が瞬時に上昇し、この高い排ガス圧力がバルブステム１０４とバルブガイド１０５の間の隙間δを通じて、バルブガイド１０５と背圧リップ１４の間の空間Ｓに導入された場合は、この空間Ｓから排ガスがさらに背圧リップ１４の内周を通過しようとする過程で、背圧リップ１４のリップ先端１４ａとバルブステム１０４の外周面１０４ａの間のクリアランスにおいて圧力損失を生じ、このため背圧リップ１４の内周よりも外周（空間Ｓ）の排ガス圧力が高くなり、その差圧が、図２に示すように背圧Ｐとして背圧リップ１４の外周面に作用する。したがって背圧リップ１４は、背圧Ｐを受けてリップ先端１４ａがバルブステム１０４の外周面１０４ａに摺動可能に接触するように変位する。 Further, for example, when the engine is started, the exhaust gas pressure at the exhaust port instantaneously rises, and this high exhaust gas pressure passes through the gap δ between the valve stem 104 and the valve guide 105, and the space between the valve guide 105 and the back pressure lip 14. When introduced into S, the clearance between the lip tip 14a of the back pressure lip 14 and the outer peripheral surface 104a of the valve stem 104 in the process of exhaust gas passing through the inner periphery of the back pressure lip 14 from the space S. The exhaust gas pressure at the outer periphery (space S) becomes higher than the inner periphery of the back pressure lip 14, and the differential pressure becomes the back pressure P as shown in FIG. Act on the surface. Accordingly, the back pressure lip 14 receives the back pressure P and is displaced so that the lip tip 14 a is slidably in contact with the outer peripheral surface 104 a of the valve stem 104.
　そして首部１２の曲げ剛性は、背圧リップ１４からメインリップ１３の腰部１３ｃにかけての曲げ剛性より小さいため、首部１２を支点とするモーメントによって、背圧リップ１４の変位がメインリップ１３をバルブステム１０４の外周面１０４ａから離間する方向へ変位させるように作用する。また、背圧Ｐの一部が背圧リップ１４のヒール１４ｂから首部１２にかけての部分を上側へ曲げ変形させるように作用することも、首部１２を支点としてメインリップ１３がバルブステム１０４の外周面１０４ａから離間する方向への変位を助長する。したがって背圧リップ１４のみがバルブステム１０４の外周面１０４ａに接触しているため、バルブステム１０４の往復動に対する摺動抵抗が小さく抑えられる。 Since the bending rigidity of the neck 12 is smaller than the bending rigidity from the back pressure lip 14 to the waist 13c of the main lip 13, the displacement of the back pressure lip 14 causes the valve lip 104 to be displaced by the moment with the neck 12 as a fulcrum. Acts to move away from the outer peripheral surface 104a. In addition, a part of the back pressure P acts so as to bend and deform the portion from the heel 14 b of the back pressure lip 14 to the neck portion 12 upward, so that the main lip 13 is the outer peripheral surface of the valve stem 104 with the neck portion 12 as a fulcrum. The displacement in the direction away from 104a is promoted. Therefore, since only the back pressure lip 14 is in contact with the outer peripheral surface 104a of the valve stem 104, the sliding resistance against the reciprocating motion of the valve stem 104 can be kept small.
　そしてこの状態では、図３（Ｂ）に示すように、背圧リップ１４は、リップ先端１４ａの上下両側でバルブステム１０４の外周面１０４ａとなす角度がθＣ＜θＤとなっているため、隙間δへ適量のエンジンオイルが流入するのを許容する。したがって、バルブステム１０４の外周面１０４ａから離間する方向へ変位したメインリップ１３に代わって、バルブステム１０４とバルブガイド１０５との間の潤滑を図ると共に、隙間δから燃焼室側へのエンジンオイルの漏れ量増大による白煙の発生やエンジンオイルの消費量の増大などを防止する機能を担うことができる。 In this state, as shown in FIG. 3B, the back pressure lip 14 has an angle of θ C <θ D with the outer peripheral surface 104a of the valve stem 104 on both upper and lower sides of the lip tip 14a. An appropriate amount of engine oil is allowed to flow into the gap δ. Therefore, in place of the main lip 13 displaced in the direction away from the outer peripheral surface 104a of the valve stem 104, lubrication between the valve stem 104 and the valve guide 105 is achieved, and engine oil from the gap δ to the combustion chamber side is obtained. The function of preventing generation of white smoke due to an increase in leakage and an increase in consumption of engine oil can be assumed.
　しかも上述のようにθＣ＜θＤとなっているため、背圧Ｐによって背圧リップ１４がメインリップ１３の内周側へ向けてめくれ上がるような変位をすることはなく、このため背圧リップ１４とバルブステム１０４の外周面１０４ａとの摺動抵抗の増大や摩耗の増大なども抑制される。 Moreover, since θ C <θ D as described above, the back pressure lip 14 does not displace toward the inner peripheral side of the main lip 13 due to the back pressure P. An increase in sliding resistance and an increase in wear between the lip 14 and the outer peripheral surface 104a of the valve stem 104 are also suppressed.
　なお、上述した実施の形態では、メインリップ１３を、ガータスプリングが装着されていないばねなしリップ型としたが、背圧リップ１４が、バルブステム１０４の外周面１０４ａとの非接触状態から接触状態へ変位したときに、首部１２を曲げ起点とするモーメントによってバルブステム１０４の外周面１０４ａから離間可能であれば、ガータスプリングが装着された仕様のものを採用することもできる。 In the embodiment described above, the main lip 13 is a springless lip type not fitted with a garter spring, but the back pressure lip 14 is in a contact state from a non-contact state with the outer peripheral surface 104a of the valve stem 104. If it is possible to move away from the outer peripheral surface 104a of the valve stem 104 by a moment with the neck portion 12 as a bending start point, a specification with a garter spring attached may be employed.
　バルブステム１０４の軸径がφ４～４０ｍｍ、背圧Ｐが０～８００ｋＰａである場合、背圧Ｐが負荷されていない通常状態での背圧リップ１４のリップ先端１４ａとバルブステム１０４の外周面１０４ａとのクリアランスは０．０５～０．４０ｍｍとし、図４に示すバルブステムと同心の仮想円筒面１０４ａ’に対して背圧リップ１４の油室側内周面１４ｃがなす角度θＣ’は５～５０°、同じく仮想円筒面１０４ａ’に対してバルブガイド側内周面１４ｄがなす角度θＤ’は５～５０°とし、背圧Ｐの負荷によってリップ先端１４ａがバルブステム１０４の外周面１０４ａに接触されたときに、この外周面１０４ａに対して油室側内周面１４ｃがなす角度θＣは５～５０°、バルブガイド側内周面１４ｄがなす角度θＤは５～５０°（但しθＣ＜θＤ）とすることが好ましい。 When the shaft diameter of the valve stem 104 is φ4 to 40 mm and the back pressure P is 0 to 800 kPa, the lip tip 14a of the back pressure lip 14 and the outer peripheral surface 104a of the valve stem 104 in a normal state where the back pressure P is not applied. The angle θ C ′ formed by the oil chamber side inner peripheral surface 14c of the back pressure lip 14 with respect to the virtual cylindrical surface 104a ′ concentric with the valve stem shown in FIG. 4 is 5 to 0.40 mm. Similarly, an angle θ D ′ formed by the valve guide side inner peripheral surface 14d with respect to the virtual cylindrical surface 104a ′ is 5 to 50 °, and the lip tip 14a is placed on the outer peripheral surface 104a of the valve stem 104 by the load of the back pressure P. The angle θ C formed by the oil chamber side inner peripheral surface 14c with respect to the outer peripheral surface 104a is 5 to 50 °, and the angle θ D formed by the valve guide inner peripheral surface 14d is 5 to 50 ° ( However, θ C <θ D ) is preferable.
　具体例としては、バルブステム１０４の軸径がφ５．５ｍｍ、背圧Ｐが５００ｋＰａである場合、背圧Ｐが負荷されていない通常状態での背圧リップ１４のリップ先端１４ａとバルブステム１０４の外周面１０４ａとのクリアランスは０．２０ｍｍとし、図４に示すバルブステムと同心の仮想円筒面１０４ａ’に対して背圧リップ１４の油室側内周面１４ｃがなす角度θＣ’は１０°、同じく仮想円筒面１０４ａ’に対してバルブガイド側内周面１４ｄがなす角度θＤ’は５０°とし、背圧Ｐの負荷によってリップ先端１４ａがバルブステム１０４の外周面１０４ａに接触されたときに、この外周面１０４ａに対して油室側内周面１４ｃがなす角度θＣは２０°、バルブガイド側内周面１４ｄがなす角度θＤは４０°とすることが好ましい。 As a specific example, when the shaft diameter of the valve stem 104 is φ5.5 mm and the back pressure P is 500 kPa, the lip tip 14a of the back pressure lip 14 and the valve stem 104 in a normal state in which the back pressure P is not loaded. The clearance with the outer peripheral surface 104a is 0.20 mm, and the angle θ C ′ formed by the oil chamber side inner peripheral surface 14c of the back pressure lip 14 with respect to the virtual cylindrical surface 104a ′ concentric with the valve stem shown in FIG. Similarly, when the angle θ D ′ formed by the valve guide inner peripheral surface 14d with respect to the virtual cylindrical surface 104a ′ is 50 °, the lip tip 14a is brought into contact with the outer peripheral surface 104a of the valve stem 104 by the load of the back pressure P. The angle θ C formed by the oil chamber side inner peripheral surface 14c with respect to the outer peripheral surface 104a is preferably 20 °, and the angle θ D formed by the valve guide side inner peripheral surface 14d is preferably 40 °.
１　バルブステムシール
１１　筒状基部（基部）
１２　首部
１３　メインリップ
１３ａ　リップ先端
１４　背圧リップ
１４ａ　リップ先端
１５　補強環
１０４　バルブステム
１０５　バルブガイド
１０９　油室 1 Valve stem seal 11 Cylindrical base (base)
12 Neck 13 Main lip 13a Lip tip 14 Back pressure lip 14a Lip tip 15 Reinforcement ring 104 Valve stem 105 Valve guide 109 Oil chamber

Claims (2)

  1. 　補強環によって補強され、バルブガイドの外周に装着される基部と、前記バルブガイドより油室側に位置し前記基部から前記補強環の油室側の端部の内径側へ延びる首部と、この首部の内径側から前記油室側へ向けて延び、前記バルブガイドに挿通されたバルブステムの外周面に摺動可能に接触されるメインリップと、前記首部の内径側から前記バルブガイド側へ向けて延びる背圧リップと、を備え、前記首部の曲げ剛性が前記背圧リップから前記メインリップの腰部にかけての曲げ剛性より小さく、前記背圧リップは前記バルブガイド側からの背圧によって前記バルブステムの外周面に摺動可能に接触され、前記背圧の無負荷時には前記バルブステムの外周面と非接触であることを特徴とするバルブステムシール。 A base portion reinforced by a reinforcing ring and attached to the outer periphery of the valve guide; a neck portion positioned on the oil chamber side of the valve guide and extending from the base portion to an inner diameter side of an end portion of the reinforcing ring on the oil chamber side; and the neck portion A main lip extending from the inner diameter side of the valve portion toward the oil chamber side and slidably contacting the outer peripheral surface of the valve stem inserted through the valve guide, and from the inner diameter side of the neck portion toward the valve guide side A back pressure lip that extends, and the bending rigidity of the neck is smaller than the bending rigidity from the back pressure lip to the waist of the main lip, and the back pressure lip is caused by back pressure from the valve guide side. A valve stem seal which is slidably contacted with an outer peripheral surface and is not in contact with the outer peripheral surface of the valve stem when the back pressure is not applied.
  2. 　背圧リップがバルブステムの外周面に摺動可能に接触された状態では、この背圧リップの油室側内周面が前記バルブステムの外周面となす角度が、この背圧リップのバルブガイド側内周面が前記バルブステムの外周面となす角度より小さいことを特徴とする請求項１に記載のバルブステムシール。 When the back pressure lip is slidably contacted with the outer peripheral surface of the valve stem, the angle formed by the oil chamber side inner peripheral surface of the back pressure lip and the outer peripheral surface of the valve stem is the valve guide of the back pressure lip. The valve stem seal according to claim 1, wherein a side inner peripheral surface is smaller than an angle formed with the outer peripheral surface of the valve stem.
PCT/JP2015/085617 2015-01-05 2015-12-21 Valve stem seal WO2016111150A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5237971A (en) * 1991-06-18 1993-08-24 Goetze Ag Valve stem seal assembly
JPH08296414A (en) * 1995-04-26 1996-11-12 Isuzu Motors Ltd Valve stem seal for internal combustion engine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5237971A (en) * 1991-06-18 1993-08-24 Goetze Ag Valve stem seal assembly
JPH08296414A (en) * 1995-04-26 1996-11-12 Isuzu Motors Ltd Valve stem seal for internal combustion engine

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