KR102389307B1 - Oil seal - Google Patents

Abstract

The oil seal is installed between the crankshaft and the crankcase to form a space for accommodating the oil therein, and a first sealing member for maintaining airtightness inside the crankcase by closely contacting the crankshaft and the crankcase by elastic restoring force; and One end is fixed to the inner side of the first sealing member and the other end is bent to slidably contact on the outer circumferential surface of the crankshaft, and as the crankshaft rotates, oil flowing out along the outer circumferential surface of the crankshaft is returned to the inside of the crankcase and a second sealing member having a spiral groove. The helical groove includes a first helical groove formed to have a first depth on a surface of the second sealing member in contact with the crankcase, and a first depth different from the first depth on the bent surface of the second sealing member so as to be continuous with the first helical groove. and a second spiral groove formed to have a second depth.

Description

Oil seal {OIL SEAL}

The present invention relates to an oil seal. More particularly, it relates to an oil seal for preventing oil inside a crankcase from leaking to the outside along an outer circumferential surface of a crankshaft.

An engine of an internal combustion engine reciprocates a piston using power generated by burning fuel, and the reciprocating motion of the piston is transmitted to a crankshaft through a connecting rod. The crankshaft may convert the reciprocating motion of the piston into rotational motion. The converted rotational kinetic energy may be transmitted to the drive shaft of the wheel through a flywheel and a transmission.

The crankshaft is connected to the connecting rod, and can rotate at high speed in the crankcase. At this time, oil is supplied into the crankcase to prevent wear and seizure of the connecting rod and crankshaft.

On the other hand, the oil inside the crankcase may leak to the outside along the outer peripheral surface of the crankshaft. To prevent this, an oil seal may be installed between the crankshaft and the crankcase. The oil seal can prevent oil inside the crankcase from leaking to the outside by maintaining airtightness between the crankshaft and the crankcase.

An object of the present invention is to provide an oil seal for preventing oil from leaking to the outside along an outer circumferential surface of a crankshaft.

In order to achieve the above object of the present invention, the oil seal according to exemplary embodiments of the present invention is installed between the crankshaft and the crankcase to form a space for accommodating oil therein, and is A first sealing member for maintaining airtightness inside the crankcase by closely contacting the crankshaft and the crankcase, and one end is fixed inside the first sealing member and the other end is bent to slide on the outer circumferential surface of the crankshaft A second sealing member contacting possible and having a spiral groove for returning oil flowing out along an outer circumferential surface of the crankshaft to the inside of the crankcase as the crankshaft rotates may be included.

The helical groove may include a first helical groove formed to have a first depth on a surface of the second sealing member in contact with the crankcase, and a first helical groove formed on the bent surface of the second sealing member to be continuous with the first helical groove. It may include a second spiral groove formed to have a second depth different from one depth.

In example embodiments, the first sealing member may further include a dust lip protruding in the crankshaft direction to contact the crankshaft to prevent an external foreign substance from being introduced into the crankcase. .

In example embodiments, the first sealing member may further include at least one outer circumferential sealing portion protruding annularly on the outer surface to contact the crankcase.

In example embodiments, the oil seal may further include a reinforcing member coupled to an inner side of the first sealing member and supporting the oil seal to maintain a constant external shape.

In exemplary embodiments, the second sealing member protrudes from the spiral groove to contact the crankshaft, and interrupts the continuity of the spiral groove so that the oil inside the crankcase is discharged when the crankshaft is stopped. It may further include at least one oil leakage preventing unit for preventing leakage to the outside along the groove.

In example embodiments, the second sealing member may be polytetrafluoroethylene (PTFE).

In exemplary embodiments, the interval between the first spiral grooves may be a first pitch, and the interval between the second spiral grooves may be a second pitch different from the first pitch.

The oil seal according to exemplary embodiments may be installed between the crankcase and the crankshaft to prevent oil inside the crankcase from flowing out along the outer circumferential surface of the crankshaft.

In particular, it is possible to reduce the stress acting on the oil seal by changing the spacing of the spiral grooves. Accordingly, it is possible to improve the followability of the oil seal to the crankshaft, and it is possible to more reliably prevent the oil inside the crankcase from leaking out at the moment when the rotation of the crankshaft is stopped.

However, the effects of the present invention are not limited to the above-mentioned effects, and may be variously expanded without departing from the spirit and scope of the present invention.

1 is a cross-sectional view illustrating an oil seal according to exemplary embodiments.
FIG. 2 is a partial cross-sectional view illustrating the oil seal of FIG. 1 .
FIG. 3 is a front view showing the second sealing member of FIG. 1 .
4 is a cross-sectional view taken along line IV-IV of FIG. 2 .
FIG. 5 is a partial cross-sectional view illustrating the second sealing member of FIG. 1 .
6 is a graph showing the leakage pressure before and after aging according to Examples and Comparative Examples.

With respect to the embodiments of the present invention disclosed in the text, specific structural or functional descriptions are only exemplified for the purpose of describing the embodiments of the present invention, and the embodiments of the present invention may be embodied in various forms and the text It should not be construed as being limited to the embodiments described in .

Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Other expressions describing the relationship between elements, such as "between" and "immediately between" or "neighboring to" and "directly adjacent to", etc., should be interpreted similarly.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that the specified feature, number, step, operation, component, part, or a combination thereof exists, and includes one or more other features or numbers. , it is to be understood that it does not preclude the possibility of the existence or addition of steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as meanings consistent with the context of the related art, and unless explicitly defined in the present application, they are not to be interpreted in an ideal or excessively formal meaning. .

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

1 is a cross-sectional view illustrating an oil seal according to exemplary embodiments. FIG. 2 is a partial cross-sectional view illustrating the oil seal of FIG. 1 . FIG. 3 is a front view showing the second sealing member of FIG. 1 . 4 is a cross-sectional view taken along line IV-IV of FIG. 2 . FIG. 5 is a partial cross-sectional view illustrating the second sealing member of FIG. 1 . 6 is a graph showing leakage pressure before and after aging according to Examples and Comparative Examples.

1 to 6 , the oil seal 100 according to exemplary embodiments is installed between the crankshaft 200 and the crankcase 300 to form a space 10 in which oil is accommodated. The first sealing member 110 , the reinforcing member 120 coupled to the inside of the first sealing member 110 , and one end is fixed to the inside of the first sealing member 110 and the other end is to the crankshaft 200 . It may include a second sealing member 130 in contact so as to be slidable.

An engine (not shown) of an internal combustion engine may burn fuel in a cylinder (not shown) and move a piston (not shown) using explosive force generated during combustion. The piston reciprocates within the cylinder, and kinetic energy of the piston may be transmitted to the crankshaft 200 through a connecting rod (not shown). The crankshaft 200 converts the reciprocating kinetic energy of the piston into rotational kinetic energy, and the converted rotational kinetic energy may be transmitted to the drive shaft of the wheel through a flywheel (not shown) and a transmission (not shown), etc. .

The crankcase 300 is installed under the cylinder block (not shown) and can accommodate a part of the crankshaft 200 . One end of the crankshaft 200 may be accommodated in the crankcase 300 , and the other end may extend to the outside of the crankcase 300 and be connected to the flywheel.

Oil may be accommodated in the inner space 10 of the crankcase 300 . The oil acts as a lubricating oil for the connecting rod and the crankshaft 200 to prevent wear and seizure of internal parts of the crankcase 300 . At this time, the oil seal 100 may be installed between the crankshaft 200 and the crankcase 300 to prevent the oil in the crankcase 300 from flowing out to the outside 20 .

In example embodiments, the oil seal 100 may include a first sealing member 110 , a second sealing member 130 , and a reinforcing member 120 .

The first sealing member 110 is installed between the crankshaft 200 and the crankcase 300 , and may have an internal space 10 for accommodating oil therein. The inner space 10 may be isolated from the outer space 20 by the first sealing member 110 . The crankshaft 200 passes through the center of the first sealing member 110 , and the outer surface of the first sealing member 110 may contact the crankcase 300 .

For example, the first sealing member may include an elastic member such as rubber. Accordingly, the first sealing member 110 can maintain the airtightness of the inner space 10 by closely contacting the crankshaft 200 and the crankcase 300 by the elastic restoring force, respectively.

In example embodiments, the first sealing member 110 may further include at least one outer circumferential sealing part 112 protruding annularly on the outer surface to contact the crankcase 300 .

Since the outer peripheral sealing part 112 is in contact with the crankcase 300 , the airtightness of the inner space 10 may be maintained even if the entire outer surface of the first sealing member 110 does not come into contact with the crankcase 300 . In addition, since the radius of the outer surface of the first sealing member 110 may be reduced, it may be easier to couple the oil seal 100 between the crankcase 300 and the crankshaft 200 .

In example embodiments, the first sealing member 110 may further include a dust lip 114 protruding inward toward the crankshaft 200 . The dust lip 114 has a ring shape and comes in contact with the crankshaft 200 to prevent foreign substances from the external space 20 from flowing into the internal space 10 .

The reinforcing member 120 is coupled to the inside of the first sealing member 110 , and in some cases, a part of the reinforcing member 120 may be inserted into the first sealing member 110 . The reinforcing member 120 may support the first sealing member 110 to maintain a constant shape. In addition, since the reinforcing member 120 supports the first sealing member 110 , contact between the outer surface of the first sealing member 110 and the crankcase 300 may be improved. For example, the reinforcing member may include a metal member such as steel.

In exemplary embodiments, the second sealing member 130 extends from the fixing part 132 fixedly installed on the first sealing member 110 and the fixing part 132 to be slidable on the crankshaft 200 . It may include a contacting oil lip 134 . In this case, the fixing part 132 and the oil lip 134 may be integrally formed.

The fixing part 132 may be coupled to the inner surface of the first sealing member 110 , and may fix the second sealing member 130 to the first sealing member 110 . 1 and 2 , it is illustrated that the fixing part 132 does not contact the reinforcing member 120 , but in some cases, the fixing part 132 may extend to contact the reinforcing member 120 .

The oil lip 134 is formed to extend from the fixing part 132 toward the crankshaft 200 and may have a ring shape. The crankshaft 200 may be inserted into the oil lip 134 . In this case, one surface of the oil lip 134 in the direction in contact with the crankshaft 200 is defined as the inner surface 134a, and the other surface opposite to the inner space 10 is defined as the outer surface 134b. to define

The oil lip 134 extending from the fixing part 132 toward the crankshaft 200 may be bent so that the inner surface 134a contacts the crankshaft 200 . That is, the oil lip 134 may include a contact portion 136 in contact with the crankshaft 200 and a bending portion 138 connecting the fixing portion 132 and the contact portion 136 . The bending part 138 may change the direction of the oil lip 134 so that the contact part 136 is in close contact with the crankshaft 200 .

On the other hand, the crankshaft 200 is not a perfect circle, and the rotation center of the crankshaft 200 may not be constant. Accordingly, the area occupied by the contact portion 136 and the bending portion 138 of the oil lip 134 may be variously changed according to the rotation of the crankshaft 200 .

The oil lip 134 may include, for example, polytetrafluoroethylene (PTFE) or rubber. The PTFE is elastically deformable, has a small coefficient of friction, and has excellent wear resistance. Accordingly, the oil lip 134 may be in close contact with the crankshaft 200 by the elastic restoring force to maintain the airtightness of the inner space 10 , and when the crankshaft 200 rotates, it may slide on the outer peripheral surface of the crankshaft 200 . can

In exemplary embodiments, the oil lip 134 is first and second for preventing oil filled in the inner space 10 from flowing out to the outer space 20 along the surface of the crankshaft 200 . It may include spiral grooves 137 and 139 and an oil leakage preventing unit 135 . In this case, both the first and second spiral grooves 137 and 139 and the oil leakage preventing part 135 may be formed on the inner surface 134a of the oil lip 134 .

3, the first spiral groove 137 and the second spiral groove 139 are formed on the inner surface 134a of the oil lip 134, respectively, and the oil lip 134 and the crankshaft 200 ) can form a spiral flow path between them. For example, the first spiral groove may be formed in an area having a radius of a first radius R1 to a second radius R2 from the center of the second sealing member, and the second spiral groove may be formed in the second It may be formed in a region having a radius from the center of the sealing member having a second radius R2 to a third radius R3. In this case, the radius of the crankshaft 200 may be the second radius R2.

For example, the spiral groove may have a triangular cross section. Alternatively, the cross section of the spiral groove may have various shapes as needed, such as a square or a semicircle.

In exemplary embodiments, the rotation direction of the first and second spiral grooves 137 and 139 may be opposite to the rotation direction of the crankshaft 200 . Accordingly, when the crankshaft 200 rotates, the oil on the surface of the crankshaft 200 may return to the inner space 10 along the first and second spiral grooves 137 and 139 .

As shown in FIG. 4 , the oil leakage preventing part 135 is formed in the contact part 136 on the inner surface 134a of the oil lip 134 , and protrudes from the first spiral groove 137 to the crankshaft 200 . can come into contact with For example, the oil leakage preventing part may have substantially the same height as the inner surface 134a of the oil lip 134 and may be integrally formed with the inner surface 134a.

While the crankshaft 200 rotates, the oil in the inner space 10 flows into the outer space 20 by the first and second spiral grooves 137 and 139 formed in the direction opposite to the rotation direction of the crankshaft 200 . ) to prevent leakage. However, since the first spiral groove 137 forms one continuous flow path on the surface of the crankshaft 200, when the rotation of the crankshaft 200 is stopped, the oil in the inner space 10 is transferred to the first It may flow out into the external space 20 along the spiral groove 137 . The oil leakage preventing unit 135 may prevent oil leakage in the internal space 10 even when the crankshaft 200 does not rotate by stopping the continuity of the first spiral groove 137 .

That is, while the crankshaft 200 rotates, it is possible to prevent the oil in the inner space 10 from flowing into the outer space 20 by the first and second spiral grooves 137 and 139 . When the rotation of the crankshaft 200 is stopped, the oil leakage preventing unit 135 separates the inner space 10 and the outer space 20 to prevent oil from leaking.

In addition, although the oil lip 134 is illustrated as having four oil leakage preventing units 135 in FIG. 3 , the number of the oil leakage preventing units 135 is not limited thereto, and the oil lip 134 may have various numbers as needed. may have leakage preventing parts of

As shown in FIG. 5 , the first spiral groove 137 has a first depth H1 from the inner surface 134a, and the interval between the spiral grooves may be a first pitch P1, and the second spiral groove Reference numeral 139 may have a second depth H2 from the inner surface 134a, and a spacing between the spiral grooves may be a second pitch P2.

In example embodiments, the first depth H1 may be different from the second depth H2 , and the first pitch P1 may be different from the second pitch P2 . That is, the second spiral groove 139 may have different depths from the first spiral groove 137 and the inner surface 134a, and the second spiral groove 139 has a pitch with the first spiral groove 137. They may be different from each other, or the second spiral groove 139 may have both a depth and a pitch different from that of the first spiral groove 137 .

Since the rotation center of the crankshaft 200 is not constant, the stress acting on the oil lip 134 as the crankshaft 200 rotates may not be constant. In particular, the stress may be concentrated on the bending portion 138 of the oil lip 134 . When the stress acting on the bending part 138 increases, the followability of the oil lip 134 to the crankshaft 200 may deteriorate. This is because the bending portion 138 is restored, and the time required for the oil lip 134 to contact the crankshaft 200 may increase. This deterioration of the followability of the oil lip 134 may cause oil leakage. Accordingly, in order to increase the followability of the oil lip 134 with respect to the crankshaft 200 and prevent oil leakage, the stress acting on the bending part 138 should be lowered.

For example, when the depth H2 and the pitch P2 of the second spiral groove 139 are greater than the depth H1 and the pitch P1 of the first spiral groove 137, respectively, the bending portion 138 It is possible to improve the followability of the oil lip 134 with respect to the crankshaft 200 by lowering the stress acting on the . The experimental results are shown in FIG. 6 .

As shown in FIG. 6 , the depth H2 and the pitch P2 of the second spiral groove 139 of the bending portion 138 are determined by the depth H1 of the first spiral groove 137 of the contact portion 136 and When formed to be larger than the pitch P1, the leakage pressure after the aging process may be higher than when the first and second spiral grooves 137 and 139 are identical to each other. The leak pressure may be a limit pressure that must be additionally applied to the bending part 138 in order to allow the oil in the internal space 10 to flow out.

In this case, the aging process is, for example, the amount of eccentricity between the center of the crankshaft 200 and the center of the opening into which the oil seal 100 formed on one side of the crankcase 300 is inserted (Shaft to bore misalignment, STBM) is 0.4mm and the eccentricity (Dynamic run-out, DRO) of the center of the crankshaft 200 according to the rotation is 0.4mm, by rotating the crankshaft 200 at a rotational speed of 3600rpm for 4 hours. can

Referring again to FIG. 6 , before the aging process, the leakage pressure may be 1.2 bar regardless of whether the spacing of the spiral grooves is uniform. That is, the oil in the inner space 10 may leak into the outer space 20 when a pressure of 1.2 bar is additionally applied to the bending part 138 .

After the aging process, when the first spiral groove 137 and the second spiral groove 139 are the same, the leakage pressure may be 0 bar. For example, the first and second spiral grooves may have a depth of 0.2 mm and a pitch of 0.4 mm, respectively. These experimental results mean that even if additional pressure is not applied to the bending part 138 , the rotation of the crankshaft 200 stops and the oil filled in the internal space 10 may leak to the outside at the same time.

In contrast, when the depth H2 and the pitch P2 of the second spiral groove 139 are greater than the depth H1 and the pitch P1 of the first spiral groove 137, after the aging process is performed may have a leak pressure of 0.2 bar. For example, the first depth and the first pitch of the first spiral groove are 0.2 mm and 0.4 mm, respectively, and the second depth and the second pitch of the second spiral groove are 0.3 mm and 0.5 mm, respectively. can be In this case, even if the rotation of the crankshaft 200 is stopped, the oil filled in the inner space 10 may not leak into the outer space 20 . This means that the stress applied to the bending portion 138 of the oil lip 134 is lowered, and accordingly, the followability of the oil lip 134 to the crankshaft 200 is improved.

As described above, the oil seal 100 according to the exemplary embodiments is installed between the crankshaft 200 and the crankcase 300 so that the oil filled in the inner space 10 leaks into the outer space 20 . can be prevented from becoming In particular, the spiral grooves 137 and 139 and the oil leakage prevention part 135 formed on the inner surface 134a of the oil lip 134 operate when the crankshaft 200 rotates and stops, respectively. Oil leakage can be prevented regardless of whether the crankshaft 200 rotates.

In particular, by changing the spacing of the spiral grooves, it is possible to more reliably prevent oil leakage at the moment when the rotation of the crankshaft 200 is stopped. Specifically, by forming the depth and pitch of the spiral grooves 139 formed in the bending portion 138 of the oil lip 134 to be greater than the depth and pitch of the spiral grooves 137 formed in the contact portion 136, the bending portion 138 ), the stress applied to it can be reduced. Accordingly, it is possible to improve the followability of the oil lip 134 with respect to the crankshaft 200 and improve the airtight maintenance performance of the oil seal 100 .

Although the above has been described with reference to the embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

10: inner space 20: outer space
100: oil seal 110: first sealing member
112: outer peripheral sealing portion 114: dust lip
120: reinforcing member 130: second sealing member
132: fixed portion 134: oil lip
134a: inner surface 134b: outer surface
135: oil leakage prevention part 136: contact part
137: first spiral groove 138: bending part
139: second spiral groove 200: crankshaft
300: crankcase R1: first radius
R2: second radius R3: third radius
P1: first pitch P2: second pitch
H1: first depth H2: second depth

Claims (7)

a first sealing member installed between the crankshaft and the crankcase to form a space for accommodating the oil therein, and for maintaining airtightness inside the crankcase by closely contacting the crankshaft and the crankcase by an elastic restoring force; and
One end is fixed to the inner side of the first sealing member and the other end is bent so as to be slidably contacted on the outer circumferential surface of the crankshaft, and as the crankshaft rotates, oil flowing out along the outer circumferential surface of the crankshaft is removed from the crank and a second sealing member having a spiral groove for returning to the inside of the case,
The spiral groove is
a first spiral groove formed to have a first depth on a surface slidably contacted on an outer circumferential surface of the crankshaft from the inside of the second sealing member; and
and a second spiral groove formed to have a second depth greater than the first depth on the bent surface of the second sealing member so as to be continuous with the first spiral groove,
The second sealing member protrudes from the first spiral groove to contact the crankshaft, and interrupts the continuity of the first spiral groove so that oil inside the crankcase closes the first spiral groove when the crankshaft is stopped. Further comprising at least one oil leakage preventing unit for preventing leakage to the outside along the
The oil seal, characterized in that the rotation direction of the first spiral groove and the second spiral groove is opposite to the rotation direction of the crankshaft. The method according to claim 1, wherein the first sealing member further comprises a dust lip protruding in the crankshaft direction to contact the crankshaft to prevent foreign substances from flowing into the crankcase. oil seal. The oil seal according to claim 1, wherein the first sealing member further comprises at least one outer circumferential sealing portion protruding annularly on an outer surface to contact the crankcase. The oil seal according to claim 1, further comprising a reinforcing member coupled to an inner side of the first sealing member and supporting the oil seal to maintain a constant external shape. delete The method of claim 1,
The second sealing member is an oil seal, characterized in that PTFE (Polytetrafluoroethylene). The method of claim 1,
The interval of the first spiral groove is a first pitch,
The oil seal, characterized in that the interval of the second spiral groove is a second pitch different from the first pitch.

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