Valve stem seal sealing device

Abstract

The present invention suppresses variations in an oil leakage rate and stabilizes the oil leakage rate.　Provided is a valve-stem-sealing seal apparatus (1) which seals the space between a valve stem (2) and a valve stem guide (3) for guiding the movement of the valve stem (2) in an axis (X) direction, and which comprises: an annular metallic ring (5) that is attached to an end section of the valve stem guide (3); and a seal body (7) that is integrally fixed to the metallic ring (5) so as to slidably contact the outer peripheral surface of the valve stem (2). The seal body (7) includes: seal lips (721, 722) that slidably contact the outer peripheral surface of the valve stem (2); a backpressure lip (725) that slidably contacts the outer peripheral surface of the valve stem (2) at a position closer to the valve stem guide (3) side than the seal lips (721, 722); and a backpressure auxiliary lip (726) that slidably contacts the outer peripheral surface of the valve stem (2) at a position between the backpressure lip (725) and the seal lips (721, 722).

Description

[Technical Field]

[0001] The present invention relates to a sealing device for a valve stem seal. [Background technology]

[0002] Conventionally, engine valves in automobile engines have used valve stem sealing devices to adjust the amount of engine oil supplied to the sliding surfaces of valve stem guides that support the valve stems of intake and exhaust valves so that they can move freely in the axial direction, and to seal out exhaust gases, etc.

[0003] This valve stem sealing device is a seal that intentionally causes oil leakage to control the amount of leakage so that an appropriate amount of oil is guided between the valve stem guide and the valve stem while the internal combustion engine is running.

[0004] In a valve stem sealing device, if the amount of oil leakage is too small, seizure will occur between the valve stem guide and the valve stem, and if the amount of oil leakage is too large, excessive oil will be introduced into the combustion chamber, causing problems such as the generation of white smoke, so it is very important to control the amount of oil leakage.

[0005] As shown in Figures 7(A) and (B), the sealing device 100 for sealing a valve stem includes a cylindrical metallic reinforcing ring 130 provided on the outer periphery of the valve stem guide 120, and a seal lip 140 formed of an elastic body such as rubber that is attached to one end of the reinforcing ring 130 by vulcanization bonding or the like and slides against the outer periphery of the valve stem 110.

[0006] In this type of valve stem sealing device 100, the seal lip 140 contacts and slides against the outer peripheral surface of the valve stem 110, thereby sealing the oil on the oil chamber side O. In addition to this, a back pressure lip 150 is provided on the port side P of the seal lip 140, which contacts and slides against the outer peripheral surface of the valve stem 110, in order to stabilize the amount of oil leakage when back pressure (bold outline arrow) is applied during port pressure load and to prevent the lip from opening when the seal lip 140 slides against the outer peripheral surface of the valve stem 110 (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-194343 Summary of the Invention [Problem to be solved by the invention]

[0008] In the sealing device 100 for a valve stem seal configured as described above, when back pressure PRS is applied during port pressure load, the axial contact force (surface pressure) of the back pressure lip 150 against the valve stem 110 becomes larger compared to when back pressure PRS is not applied (A), as shown in Figure 8(B). In such a case, depending on the setting conditions such as the use conditions and the amount of oil leakage from the lip, there is a concern that the amount of oil leakage will increase due to oil scraping out from the back pressure lip 150 when the valve stem 110 moves toward the oil chamber side O during valve closing.

[0009] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a sealing device for a valve stem seal that can suppress variation in the amount of oil leakage and stabilize the amount of oil leakage. [Means for solving the problem]

[0010] The present invention provides a sealing device for a valve stem that seals a gap between a valve stem and a valve stem guide that guides the axial movement of the valve stem, and includes: an annular metal ring attached to the end of the valve stem guide; and a seal body that is fixed integrally with the metal ring and is in slidable contact with the outer peripheral surface of the valve stem. The seal body has a seal lip that is in slidable contact with the outer peripheral surface of the valve stem, a back pressure lip that is in slidable contact with the outer peripheral surface of the valve stem on the valve stem guide side of the seal lip, and a back pressure auxiliary lip that is in slidable contact with the outer peripheral surface of the valve stem between the back pressure lip and the seal lip.

[0011] It is preferable that a plurality of the back pressure assisting lips are provided at equal intervals in the circumferential direction.

[0012] Preferably, the back pressure assist lip has no contact surface at a portion thereof.

[0013] Preferably, the back pressure assist lip has a contact surface over the entire periphery. [Effects of the Invention]

[0014] According to the present invention, it is possible to realize a sealing device for a valve stem seal that can suppress variations in the amount of oil leakage and stabilize the amount of oil leakage. [Brief explanation of the drawings]

[0015] [Figure 1] 1A is a cross-sectional view showing an installed state of a sealing device for a valve stem seal according to a first embodiment of the present invention, and FIG. 1B is a half cross-sectional view showing the configuration of the sealing device for a valve stem seal. [Figure 2] 1 is a perspective cross-sectional view showing the configuration of a sealing device for sealing a valve stem according to a first embodiment of the present invention. [Figure 3]1A is a cross-sectional view showing the axial contact force (surface pressure) distribution of the back pressure lip when no back pressure is applied in a sealing device for a valve stem seal according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view showing the axial contact force (surface pressure) distribution of the back pressure lip when back pressure is applied. [Figure 4] 4 is a graph showing the axial contact force of the back pressure lip versus the port pressure of the sealing device for a valve stem seal according to the first embodiment of the present invention. [Figure 5] 5A is a cross-sectional view showing the configuration of a sealing device for sealing a valve stem according to a second embodiment of the present invention, and FIG. 5B is a half cross-sectional view showing the configuration of the sealing device for sealing a valve stem. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of a back pressure auxiliary lip in a sealing device for a valve stem seal according to another embodiment of the present invention. [Figure 7] 1A is a cross-sectional view showing a state in which a conventional sealing device for a valve stem seal is installed, and FIG. 1B is a half cross-sectional view showing the configuration of the conventional sealing device for a valve stem seal. [Figure 8] FIG. 1A is a cross-sectional view showing the axial contact force (surface pressure) distribution of the back pressure lip when no back pressure is applied in a conventional sealing device for a valve stem seal, and FIG. 1B is a cross-sectional view showing the axial contact force (surface pressure) distribution of the back pressure lip when back pressure is applied. DETAILED DESCRIPTION OF THE INVENTION

[0016] First Embodiment A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view (A) showing an installed state of a sealing device 1 for a valve stem seal according to the first embodiment of the present invention, and a half cross-sectional view (B) showing the configuration of the sealing device 1 for a valve stem seal. FIG. 2 is a perspective cross-sectional view showing the configuration of the sealing device for a valve stem seal according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the axial contact force (surface pressure) distribution of the back pressure lip when no back pressure is applied in the sealing device for a valve stem seal according to the first embodiment of the present invention (A), and the axial contact force (surface pressure) distribution of the back pressure lip when back pressure is applied (B). FIG. 4 is a graph showing the axial contact force of the back pressure lip versus port pressure in the sealing device for a valve stem seal according to the first embodiment of the present invention.

[0017] In the description of the first embodiment of the present invention, for convenience of explanation, the direction of arrow a in the axial direction along the axis X is designated as the oil chamber side O, and the direction of arrow b in the axial direction along the axis X is designated as the port side P.

[0018] 1(A) and 1(B), the sealing device 1 for a valve stem seal according to this embodiment is used for, for example, an exhaust system valve provided in the cylinder head of an automobile engine. However, the sealing device 1 for a valve stem seal is not limited to this, and may also be used for an intake system valve.

[0019] The valve stem sealing device 1 is attached to a valve stem guide 3 that supports the valve stem 2 so that it can reciprocate in the axial direction, and adjusts the amount of engine oil leaking from the oil chamber side O that is supplied to the sliding surface between the valve stem 2 and the valve stem guide 3, while also sealing off exhaust gases and the like that are discharged from the port side P.

[0020] The sealing device 1 for valve stem seals is formed in an annular shape with both ends open, and has a tip opening 11 at one end in the direction of axis X and a root opening 13 at the other end in the axial direction. The tip opening 11 is an opening that faces the oil chamber side O when the sealing device 1 for valve stem seals is attached to the valve stem guide 3. The root opening 13 is an opening where the sealing device 1 for valve stem seals is first inserted into the valve stem guide 3.

[0021] The sealing device 1 for sealing a valve stem includes a metal ring 5, and a seal body 7 made of a rubber-like elastic material is fixed integrally to the metal ring 5. The metal ring 5 and the seal body 7 are fixed integrally by vulcanization adhesion.

[0022] The metal ring 5 is a metal annular member that covers from the outside one end (oil chamber side O) in the axial X direction of the valve stem guide 3. The metal ring 5 has a cylindrical portion (hereinafter referred to as the "cylindrical portion") 51 that has a predetermined length along the axial X direction, and an annular portion (hereinafter referred to as the "annular portion") 52 that extends from the end of the cylindrical portion 51 in the axial X direction (oil chamber side O) toward the outer peripheral surface of the valve stem 2.

[0023] The cylindrical portion 51 has an inner diameter larger than the outer diameter of the valve stem guide 3. The other end (port side P) of the cylindrical portion 51 in the axial X direction forms the root opening 13 described above.

[0024] The annular portion 52 has an open end 52h in its center, and the inner diameter of the open end 52h is larger than the outer diameter of the valve stem 2. That is, in the metal ring 5, there is a gap such that the open end 52h of the annular portion 52 and the outer peripheral surface of the valve stem 2 do not come into contact with each other.

[0025] The seal body 7 has a seal fitting portion 71, a seal main body portion 72, and a seal connection portion 73 that connects the seal fitting portion 71 and the seal main body portion 72. The seal fitting portion 71 has a predetermined length along the direction of the axis X and is a cylindrical portion fixed to the inner peripheral surface of the metal ring 5, and is fitted and fixed to the outer peripheral surface of the valve stem guide 3. The seal fitting portion 71 has a length such that it does not protrude from the other end (port side P) of the cylindrical portion 51 of the metal ring 5.

[0026] The seal connection portion 73 is an annular portion that extends from one end (oil chamber side O) of the seal fitting portion 71 in the axial X direction toward the outer circumferential surface of the valve stem 2 so as to entirely cover the annular portion 52 of the metal ring 5, and has its inner end portion integrally connected to the seal main body 72. The seal connection portion 73 is fixed integrally to the annular portion 52 of the metal ring 5.

[0027] The seal main body 72 is an overall cylindrical part that is fixed integrally to cover the opening end 52h of the annular portion 52 of the metal ring 5, and is arranged to slidably contact the outer peripheral surface of the valve stem 2.

[0028] The seal body 72 has an annular recess 72r formed on its outer circumferential surface, and a garter spring 9 is attached to the recess 72r. The garter spring 9 increases the axial contact force (surface pressure) of the seal body 72 against the valve stem 2 by its tension force.

[0029] The seal main body 72 is bent in an approximately L-shape from near the center, which is near the opening end 52h of the annular portion 52 of the metal ring 5, and has a truncated conical surface 72a (shown by a dashed line) closer to the oil chamber side O than the center, and a truncated conical surface 72b (shown by a dashed line) closer to the port side P than the center.

[0030] The seal body 72 has a truncated conical surface 72a that has a main lip 721 and a sub-lip 722 that are in slidable contact with the outer peripheral surface of the valve stem 2. The main lip 721 and the sub-lip 722 are provided consecutively in this order from near the center toward the oil chamber side O: the sub-lip 722, then the main lip 721.

[0031] Here, the main lip 721 is provided in the shape of a continuous, endless circle in the circumferential direction. A plurality of sub-lips 722 are provided at predetermined intervals in the circumferential direction. However, this is not limiting, and the sub-lips 722 may also be provided in the shape of a continuous, endless circle in the circumferential direction, or multiple sub-lips may be arranged at unequal intervals in the circumferential direction. The presence of the garter spring 9 applies a tension force to the main lip 721 and sub-lip 722, pressing them against the outer circumferential surface of the valve stem 2.

[0032] The main lip 721 is located closer to one end (oil chamber side O) than the sub-lip 722 in the direction of the axis X, and is adjacent to the tip opening 11. The main lip 721 is a conical annular portion whose diameter gradually decreases toward the outer peripheral surface of the valve stem 2, and has a lip tip portion that comes into contact with the outer peripheral surface of the valve stem 2. The inner diameter of the main lip 721 is smaller than the outer diameter of the valve stem 2, and has a predetermined interference with the valve stem 2.

[0033] The sub-lip 722 is positioned adjacent to the main lip 721 on the other end side (port side P) of the main lip 721 in the axial X direction, and like the main lip 721, is a wedge-shaped portion whose diameter gradually decreases toward the outer peripheral surface of the valve stem 2.

[0034] The sub-lip 722 also has a lip tip that comes into contact with the outer circumferential surface of the valve stem 2. The inner diameter of the sub-lip 722 is smaller than the outer diameter of the valve stem 2, and has a predetermined interference with the valve stem 2.

[0035] In this case, the amount of protrusion of the sub-lip 722 from the truncated conical surface 72a is set slightly larger than the amount of protrusion of the main lip 712 from the truncated conical surface 72a, but because the truncated conical surface 72a narrows toward the oil chamber side O, the tightening margin of the main lip 721 relative to the valve stem 2 is set larger than the tightening margin of the sub-lip 722 relative to the valve stem 2.

[0036] That is, the seal body 72 has a main lip 721 formed in a position close to the oil chamber side O, as well as a sub-lip 722 formed adjacent to the main lip 721 and closer to the port side P than the main lip 721, thereby preventing the main lip 721 from coming into contact with the outer peripheral surface of the valve stem 2.

[0037] Specifically, when the sub-lip 722 comes into contact with the outer peripheral surface of the valve stem 2 following the main lip 721, the sub-lip 722 suppresses the axial contact force (surface pressure) that presses the main lip 721 against the outer peripheral surface of the valve stem 2. This allows the seal body 72 to allow an appropriate amount of oil from the oil chamber side O to leak to the port side P via the main lip 721 and the sub-lip 722.

[0038] Furthermore, as long as it is possible to allow an appropriate amount of oil from the oil chamber side O to leak to the port side P, the interference of the main lip 721 does not necessarily have to be greater than the interference of the sub-lip 722; the interference of the main lip 721 may be the same as the interference of the sub-lip 722, or conversely, the interference of the main lip 721 may be smaller than the interference of the sub-lip 722.

[0039] The seal body 72 also has a back pressure lip 725 and a back pressure auxiliary lip 726 that are in slidable contact with the outer peripheral surface of the valve stem 2 on its truncated conical surface 72b. The back pressure lip 725 and the back pressure auxiliary lip 726 are provided consecutively in this order from near the center toward the port side P: back pressure auxiliary lip 726, back pressure lip 725.

[0040] The back pressure lip 725 protrudes diagonally downward from the end closer to the port side P toward the outer peripheral surface of the valve stem 2, and has a lip tip that comes into contact with the outer peripheral surface of the valve stem 2. The back pressure lip 725 prevents the back pressure PRS from inside the combustion chamber from reaching the main lip 721 and sub-lip 722 through the gap between the valve stem guide 3 and the valve stem 2, causing the valve to open or causing excessive deformation.

[0041] Furthermore, the seal main body 72 has a back pressure auxiliary lip 726 that is located between the back pressure lip 725 and the sub-lip 722 and is provided adjacent to the back pressure lip 725 near the open end 52h of the metal ring 5 on the truncated conical surface 72b. The back pressure auxiliary lip 726 is a part that protrudes in a wedge shape toward the outer peripheral surface of the valve stem 2 and has a lip tip portion 726a that comes into contact with the outer peripheral surface of the valve stem 2.

[0042] The inner diameter of the back pressure lip 725 is smaller than the outer diameter of the valve stem 2, and has a predetermined interference fit with the valve stem 2. The inner diameter of the back pressure auxiliary lip 726 is smaller than the outer diameter of the valve stem 2, and has a predetermined interference fit with the valve stem 2.

[0043] In this case, the amount by which the back pressure auxiliary lip 726 protrudes from the truncated conical surface 72b is set slightly larger than the amount by which the back pressure lip 725 protrudes from the truncated conical surface 72b. However, since the truncated conical surface 72b narrows in diameter toward the port side P, the interference between the back pressure lip 725 and the valve stem 2 is set larger than the interference between the back pressure auxiliary lip 726 and the valve stem 2.

[0044] The back pressure auxiliary lips 726 are arranged at equal intervals in the circumferential direction, but are not limited to this, and the back pressure auxiliary lips 726 may be arranged at unequal intervals in the circumferential direction.

[0045] Specifically, when the back pressure auxiliary lip 726 comes into contact with the outer peripheral surface of the valve stem 2 following the back pressure lip 725, and receives back pressure PRS (pressure due to exhaust gas from the exhaust port) from the port side P as shown by the bold arrow in Figure 3(B), the pressure of the back pressure PRS is dispersed to the back pressure auxiliary lip 726.

[0046] This reduces the pressure on the back pressure lip 725, causing the back pressure lip 725 to deform so that it clings to the outer peripheral surface of the valve stem 2, i.e., reducing the axial contact force (surface pressure) that presses the back pressure lip 725 against the outer peripheral surface of the valve stem 2.

[0047] As can be seen from Figures 3(A) and (B), even when there is back pressure PRS (B), compared to when there is no back pressure PRS (A), the back pressure auxiliary lip 726 is in contact with the outer peripheral surface of the valve stem 2, so the pressure is dispersed to the back pressure auxiliary lip 726, and thus the increase in the axial contact force (surface pressure) of the back pressure lip 725 is reduced.

[0048] As a result, when the valve stem 2 moves toward the oil chamber side O to close the valve, the amount of oil from the oil chamber side O that leaks out to the port side P via the main lip 721 and the sub lip 722 is reduced by scraping it out to the port side P by the back pressure lip 725, thereby preventing the amount of oil leakage from increasing.

[0049] The back pressure assistance lip 726 has an arc-shaped lip tip 726a with as large a chamfering radius as possible so that the oil (oil film) that passes through the back pressure lip 725 when the valve stem 2 is open can be returned as is when the valve is closed. In other words, the lip tip 726a of the back pressure assistance lip 726 is set so that the contact surface pressure gradient is the same between the oil chamber side O and the port side P. The shape of the lip tip 726a may be a gentle arc that approximates point contact, or a flat shape that makes surface contact with the outer circumferential surface of the valve stem 2.

[0050] In this way, by setting the R chamfer radius of the lip tip 726a of the back pressure assisting lip 726 as large as possible, an increase in the amount of oil scraped out by the lip tip 726a when the valve is closed is suppressed.

[0051] That is, even when the valve stem 2 is open, the back pressure auxiliary lip 726 comes into contact with the outer peripheral surface of the valve stem 2, preventing a large increase in the surface pressure of the back pressure lip 725, and allowing the oil that has passed through the back pressure lip 725 to return as is when the valve is closed. Note that the lip tip 726a of the back pressure auxiliary lip 726 is shaped so as not to contribute to the appropriate amount of oil leakage from the oil chamber side O to the port side P.

[0052] Note that any number of back pressure auxiliary lips 726 can be provided depending on the axial contact force (surface pressure) generated at the lip tip of the back pressure lip 725 that contacts the outer circumferential surface of the valve stem 2 and the amount of fluctuation in the amount of oil leakage due to the back pressure PRS. Furthermore, the back pressure auxiliary lips 726 may each have a different circumferential length.

[0053] In this case, the axial contact force (surface pressure) of the back pressure lip 725 is small in the portion of the seal main body 72 where the back pressure auxiliary lip 726 is present, whereas the axial contact force (surface pressure) of the back pressure lip 725 is large in the portion where the back pressure auxiliary lip 726 is not present.

[0054] Therefore, in the seal main body 72, the amount of oil leakage scraped off by the back pressure lip 725 can be adjusted as desired depending on the length of the back pressure auxiliary lip 726 and how many are provided and at what intervals.

[0055] In the above configuration, the sealing device 1 for valve stem sealing has a back pressure auxiliary lip 726 adjacent to the truncated conical surface 72b, which is the inner surface of the seal main body 72, in addition to the back pressure lip 725, and the lip tip portion 726a of the back pressure auxiliary lip 726 is made to contact the outer surface of the valve stem 2.

[0056] 4, the sealing device 1 for a valve stem seal with the back pressure auxiliary lip 726 indicated by the white circle can reduce the axial contact force (surface pressure) generated at the lip tip of the back pressure lip 725 compared to when the back pressure auxiliary lip 726 is not provided (no back pressure auxiliary lip indicated by the black circle). In this case, according to experiments, the axial contact force (surface pressure) generated at the lip tip of the back pressure lip 725 decreases by approximately 9 to 11 percent as the back pressure PRS increases.

[0057] In this way, when the back pressure auxiliary lip 726 is not provided in the sealing device 1 for valve stem sealing, the axial contact force (surface pressure) of the back pressure lip 725 against the outer peripheral surface of the valve stem 2 becomes significantly larger as the back pressure PRS increases, such as when the port pressure is loaded, compared to when the back pressure auxiliary lip 726 is provided.

[0058] In this case, the oil that leaks from the back pressure lip 725 when the valve stem 2 is open is scraped off by the back pressure lip 725 when the valve stem 2 is closed, and the oil does not return completely to the oil chamber side O, resulting in a decrease in the amount of oil on the oil chamber side O.

[0059] However, as in the sealing device 1 for valve stem seal, by providing a back pressure auxiliary lip 726 adjacent to the back pressure lip 725 in addition to the back pressure lip 725, the axial contact force (surface pressure) generated at the lip tip of the back pressure lip 725 is reduced overall compared to when the back pressure auxiliary lip 726 is not provided, so that the variation in the amount of oil leakage caused by oil scraped off by the back pressure lip 725 when the valve is closed is reduced and the amount of oil leakage can be stabilized.

[0060] Furthermore, the back pressure auxiliary lips 726 of the sealing device 1 for a valve stem seal are provided in multiple locations at equal intervals around the circumference in accordance with the amount of fluctuation in the amount of oil leakage, thereby stabilizing the amount of oil leakage when port pressure is applied.

[0061] Furthermore, the back pressure auxiliary lip 726 of the sealing device 1 for a valve stem seal has an R chamfer radius of the lip tip 726a that is as large as possible, and the contact surface pressure gradient is made the same between the oil chamber side O and the port side P. This prevents the lip tip 726a from scraping out oil when the valve is closed, and stabilizes the amount of oil leakage.

[0062] <Second embodiment> As shown in Figure 5, in which the same reference numerals are used to denote parts corresponding to those in Figure 1, the sealing device 1s for a valve stem seal in the second embodiment has the same basic structure as the sealing device 1 for a valve stem seal in the first embodiment, but instead of the back pressure auxiliary lip 726, a back pressure auxiliary lip 726s is provided that is in contact over the entire circumferential surface of an endless circle that is continuous in the circumferential direction.

[0063] In this valve stem sealing device 1s, a back pressure auxiliary lip 726s that contacts the entire circumferential surface can be used when there is no effect on the amount of oil leakage, and the effect is the same as in the first embodiment, suppressing variations in the amount of oil leakage and stabilizing the amount of oil leakage. Note that a surface pressure gradient may be intentionally provided for the back pressure auxiliary lip 726s. In this case, the sealing function, i.e., the amount of oil leakage, can be adjusted via the back pressure auxiliary lip 726s.

[0064] <Other embodiments> Although the sealing device 1, 1s for a valve stem seal of the present invention has been described above using preferred embodiments, the sealing device 1, 1s for a valve stem seal of the present invention is not limited to the configuration of the above embodiments. For example, in the first and second embodiments, any combination can be adopted, such as providing an annular sub-lip 722 for the back pressure auxiliary lips 726 that are provided at equal intervals, or providing an annular sub-lip 722 for the annular back pressure auxiliary lips 726s.

[0065] Furthermore, in the first embodiment described above, a case has been described in which a plurality of back pressure auxiliary lips 726 are provided at equal intervals, but the present invention is not limited to this, and back pressure auxiliary lips 727 having a shape as shown in FIG. 6 may also be provided at equal intervals.

[0066] In this case, a notch 727k is provided in a portion of the back pressure auxiliary lip 727. As a result, the seal main body 72 can suppress an increase in sliding resistance compared to a back pressure auxiliary lip 727 without the notch 727k, while suppressing oil scraping out when the valve stem 2 is closed and stabilizing the amount of oil leakage, as in the first and second embodiments. Note that the back pressure auxiliary lips 727 are not limited to being provided at equal intervals, and multiple back pressure auxiliary lips 727 may be arranged at uneven intervals in the circumferential direction.

[0067] In addition, a person skilled in the art can appropriately modify the sealing device 1, 1s for sealing a valve stem according to the present invention and change the combination of various components in accordance with conventionally known knowledge. As long as the components of the present invention are still maintained even after such modifications, they are of course included in the scope of the present invention. [Explanation of symbols]

[0068] 1,1s,100...Sealing device for valve stem seal, 2,110...Valve stem, 3,120...Valve stem guide, 5...Metal ring, 7...Seal body, 9...Garter spring, 11...Tip opening, 13...Root opening, 51...Cylindrical portion, 52...Annular portion, 52h...Opening end, 71...Seal fitting portion, 72...Seal main body portion, 73...Seal connection portion, 130...Reinforcing ring, 140...Seal lip, 150...Back pressure lip, 721...Main lip, 722...Sub lip, 725...Back pressure lip, 726, 727...Back pressure auxiliary lip, 726a...Lip tip portion.

Claims

1. A sealing device for a valve stem that seals a gap between a valve stem and a valve stem guide that guides the axial movement of the valve stem, a metal ring attached to an end of the valve stem guide; and a seal body fixed integrally with the metal ring and in slidable contact with the outer peripheral surface of the valve stem. Equipped with The seal body is a seal lip that slidably contacts the outer peripheral surface of the valve stem; a back pressure lip that slidably contacts the outer peripheral surface of the valve stem on the valve stem guide side of the seal lip; a back pressure auxiliary lip between the back pressure lip and the seal lip, the back pressure auxiliary lip being in slidable contact with the outer peripheral surface of the valve stem; and The back pressure auxiliary lip has no contact surface in a portion of its circumferential direction.

2. A valve stem sealing device that seals a gap between a valve stem and a valve stem guide that guides the axial movement of the valve stem, a metal ring attached to an end of the valve stem guide; and a seal body fixed integrally with the metal ring and in slidable contact with the outer peripheral surface of the valve stem. Equipped with The seal body is a seal lip that slidably contacts the outer peripheral surface of the valve stem; a back pressure lip that slidably contacts the outer peripheral surface of the valve stem on the valve stem guide side of the seal lip; a back pressure auxiliary lip between the back pressure lip and the seal lip, the back pressure auxiliary lip being in slidable contact with the outer peripheral surface of the valve stem; and The back pressure assisting lips are provided in plurality at equal intervals in the circumferential direction. Sealing device for valve stem seal.

Images