Dynamically vented crankshaft and seal assembly

Abstract

The dynamically ventilated crankshaft seal and systems and methods thereof may include a seal assembly (200, 201, 300, 400) consisting of a wear sleeve (240, 245, 430), a main seal (220, 420), a dust seal (230, 430), and a plurality of circumferentially spaced vent holes (242 / 244, 246, 444 / 446). Each of the vent holes (242 / 244, 246, 444 / 446) may be defined by at least a channel (242, 246, 446). The channel (242, 246, 446) may be defined in or by the wear sleeve (240, 245, 430), which may be the primary wear sleeve (240, 430) or the secondary wear sleeve (245). Additionally, each of the vents (242 / 244, 246, 444 / 446) can extend from a first side of the seal assembly between the main seal (220, 420) and the dust seal (230, 430) (250). The angle (W) between the channel length axis and the path of circumferential motion of the channels (242, 246, 446) can be 90 degrees, an acute angle, or an obtuse angle for each of the channels (242, 246, 446).

Description

[Technical Field]

[0001] The present disclosure relates to dynamically vented crankshaft seals and systems and methods thereof. [Background technology]

[0002] Many rotatable shaft mechanisms within machines, such as engine crankshafts within engines, use shaft seals to maintain lubricating oil within the machine and on the surfaces of rotating components. Front and back crankshaft seals are commonplace for engine crankshafts. These seals are typically mounted within the cylinder block, such as by press fitting, to form a static seal with the cylinder block and a dynamic seal around the rotating crankshaft. The dynamic seal portion in these examples typically includes a non-metallic material, such as a polytetrafluoroethylene (PTFE) material, that contacts the outer rotating surface of the crankshaft or a wear sleeve or the like fitted thereto. Oil within the engine crankcase can travel to some extent between the dynamic seal portion and the crankshaft itself, helping to lubricate the mating surfaces.

[0003] Crankshaft seals can be susceptible to carbonization of hydrocarbon-based lubricants, leading to contamination of the pump spiral groove. The spiral groove is molded or cut into the contact joint of the sealing lip, which can be made of PTFE, as described above. The rate of carbonization increases with the speed of the rotating shaft, the radial load on the sealing lip, and the temperature and aging of the lubricant. High loads, speeds, and temperatures can lead to the buildup of heat generated by sliding friction between the static sealing lip and the rotating element. The lubricant can begin to burn and form carbon debris if the temperature of the sliding contact joint exceeds its flash point. Carbon debris can gradually accumulate in the pump groove and degrade pump performance to the point of causing external leakage. Increased frictional heating can also be exacerbated by vacuum formation at the joint between the main lip and the dust lip, which is inherently designed to prevent external debris from entering the main sealing joint. The stability and strength of the negative pressure at the joint area can depend heavily on the dust lip design. High negative pressure can cause a lack of airflow through the main lip spiral grooves, which helps cool the contact joint, and increases the radial load due to increased bending of the main lip towards the joint.

[0004] U.S. Patent Publication No. 2022 / 0381347 (the "'347 Publication") describes a seal assembly for a rotatable shaft assembly, including a seal housing and a main seal and a dust seal extending circumferentially around the seal housing central axis. The dust seal is formed by a sealing layer having a radially inward-facing dust seal lip and having multiple vent openings formed therein, and a debris-blocking filter layer attached to the sealing layer and positioned across the vent openings. According to the '347 Publication, the main seal and dust seal help maintain lubricating oil within the seal cavity, and the dust seal prevents debris from entering while venting the seal cavity to limit carbonization of the oil on the seal assembly components. Summary of the Invention

[0005] In one aspect of the present disclosure, a seal assembly is disclosed, or is provided or implemented. The seal assembly may include a wear sleeve, a main seal, a dust seal, and a plurality of circumferentially spaced vents, each of which is formed by at least a channel, each of which extends from a first side of the seal assembly between the main seal and the dust seal, and an angle between a channel length axis of the channel and a circumferential path of motion for each of the channels is 90 degrees, an acute angle, or an obtuse angle.

[0006] In another aspect, a method is disclosed or may be implemented. The method may include providing a wear sleeve surrounding a rotatable shaft and providing a seal assembly surrounding the rotatable shaft. The seal assembly may include a housing, a main seal attached to the housing, the main seal including a mounting portion and a main seal lip, the main seal being curved in a side elevational view of the seal assembly, a dust seal having a mounting portion, and a plurality of vents spaced circumferentially around the seal assembly. Each of the vents is formed by a channel, and each of the vents extends from an exterior of the seal assembly to a circumferential seal cavity between the main seal and the dust seal to prevent or minimize vacuum formation within the circumferential seal cavity. An angle between a channel length axis of the channel and a path of circumferential motion of the rotatable shaft is 90 degrees, an acute angle, or an obtuse angle relative to each of the channels.

[0007] According to yet another aspect, a rotatable shaft assembly is disclosed or may be implemented or provided. The rotatable shaft assembly may include a rotatable shaft defining a shaft rotation axis, a wear sleeve surrounding the rotatable shaft and attached directly to the rotatable shaft, and a seal assembly surrounding the rotatable shaft. The seal assembly may include a housing, a main seal attached to the housing, the main seal including a mounting portion and a main seal lip, the main seal being curved in a side elevational view of the seal assembly, a dust seal having a mounting portion, and a plurality of vent holes spaced circumferentially around the seal assembly. Each of the vent holes extends from an exterior of the seal assembly to a circumferential seal cavity between the main seal and the dust seal to prevent or minimize vacuum formation within the circumferential seal cavity. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a mechanical system according to one or more embodiments of the present disclosure. [Figure 2] FIG. 2 is an elevational view of a seal assembly according to one or more embodiments of the present disclosure. [Figure 3] FIG. 3 is a schematic diagram of the seal assembly in FIG. [Figure 4] FIG. 4 shows front and side cross-sectional views of a crankshaft seal according to one or more embodiments of the present disclosure. [Figure 5] FIG. 5 shows the orientation angle of the ventilation channels of the crankshaft seal of FIG. [Figure 6] FIG. 6 shows front and side cross-sectional views of a crankshaft seal according to one or more embodiments of the present disclosure. [Figure 7] FIG. 7 shows the orientation angle of the ventilation channels of the crankshaft seal of FIG. [Figure 8] FIG. 8 shows front and side cross-sectional views of a crankshaft seal according to one or more embodiments of the present disclosure. [Figure 9] FIG. 9 shows the orientation angle of the ventilation channels of the crankshaft seal of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] SUMMARY OF THE INVENTION Embodiments of the present disclosure relate to dynamically ventilated crankshaft seals and systems and methods thereof.

[0010] FIG. 1 illustrates a mechanical system 10 according to one or more embodiments of the present disclosure. The mechanical system 10 may include a housing 12 (shown diagrammatically) and a rotatable shaft assembly 14 configured to be supported for rotation within the housing 12. The mechanical system 10 may be or include an internal combustion engine system, such as a diesel engine system. The rotatable shaft assembly 14 may include a rotatable shaft 16 defining a shaft rotation axis 18 extending between a first axial end 20 and a second axial end 22. In the illustrated embodiment, the rotatable shaft 16 includes an engine crankshaft including a crank pin 24 and a balance weight 26, although embodiments of the present disclosure are not limited to the particular configuration illustrated in FIG. 1 . It will be appreciated, therefore, that the rotatable shaft assembly 14 may rotate within the housing 12 during operation to convert linear piston motion into torque for any of a wide variety of known applications. The rotatable shaft 16 may include a bearing surface and may be rotationally supported by bearing caps or the like according to any suitable structure.

[0011] The rotatable shaft assembly 14 may further include a first seal assembly 200 positionable on the rotatable shaft 16 at a first axial end 20 and a second seal assembly 201 positionable on the rotatable shaft 16 at a second axial end 22. The first seal assembly 200 and the second seal assembly 201 may be of the same, similar, or different configurations. For example, as shown in FIG. 1 , the second seal assembly 201 may have a larger diameter and circumference than the first seal assembly 200. A torsional damper 38 may be coupled to the first axial end 20 of the rotatable shaft 16 adjacent the first seal assembly 200.

[0012] As shown, first seal assembly 200 can be considered a front crankshaft seal and second seal assembly 201 can be considered a back crankshaft seal based on their positioning relative to rotatable shaft 16. Discussion and description herein of seal assembly 200 should be understood to refer analogously to features of seal assembly 201, as well as any of the various other embodiments contemplated herein.

[0013] 2 and 3 , seal assembly 200 may include a seal housing 210, a main seal 220, and a dust seal 230. Each of seal housing 210, main seal 220, and dust seal 230 may extend circumferentially around shaft rotation axis 18 (per FIG. 1 ). Seal housing 210 may be further understood to define a central seal axis 202, and each of seal housing 210, main seal 220, and dust seal 230 extend circumferentially around central seal axis 202. In one implementation, seal housing 210 may be formed of a metallic material such as steel, main seal 220 may be formed of a polymeric material such as a PTFE material, and / or dust seal 230 may have a layered structure in some embodiments, with the layers being formed of non-metallic materials, as discussed further herein.

[0014] A wear sleeve 240, which can rotate with the rotatable shaft 16, may extend through the seal assembly 200 and may be positioned radially between the main seal 220 and the rotatable shaft 16 and radially between the dust seal 230 and the rotatable shaft 16. The wear sleeve 240 may be considered a primary sleeve. The wear sleeve 240 may extend around the entire circumference of the rotatable shaft 16. The wear sleeve 240 may be formed of a suitable metallic material, such as steel, and may be an interference fit onto the rotatable shaft 16. Furthermore, the seal housing 210 may be an interference fit into a housing 12, such as a cylinder block, within the mechanical system 10. Thus, a static seal may be formed between the seal housing 210 and the housing 12, and a dynamic seal may be formed between the main seal 220 and the wear sleeve 240, which, as described above, can rotate with the rotatable shaft 16.

[0015] 4 , main seal 220 may include a radially outward mounting portion 224 coupled to seal housing 210 and a radially inward main seal lip 226. In some embodiments, main seal lip 226 may be thickened relative to other portions of main seal 220, although this disclosure is not limited thereby. Radially inward main seal lip 226 may also form a terminal or inner peripheral edge of main seal 220. Radially outward mounting portion 224 may form an outer peripheral edge of main seal 220.

[0016] The main seal 220 can be deformed between the seal housing 210 and the wear sleeve 240. As shown in FIG. 4 , the main seal 220 can be curved in axial appearance such that the radially inward main seal lip 226 is positioned to seal around the wear sleeve 240 at a first axial position spaced from the radially outward mounting portion 224. The main seal 220 can have at least some internal elastic restoring force such that, when unbiased, the main seal 220 can tend to assume a planar or near-planar configuration than depicted in the drawings. Deformation of the main seal 220 in response to the inward bias can help maintain the radially inward squeeze around the wear sleeve 240.

[0017] As mentioned above, the main seal 220 may be curved in axial appearance relative to the seal central axis 202 and the shaft rotation axis 18, or these axes may be collinear. As used herein, "axial" may refer to a direction along the axes 202 and 18, and "radial" may refer to a direction perpendicular to the axes 202 and 18. The wear sleeve 240 may have a linear, e.g., rectangular, axial or side appearance. In the illustrated embodiment, the main seal 220 may be deformed between the seal housing 210 and the wear sleeve 240 to protrude from the seal housing 210 in a first axial direction. The dust seal 230 may be deformed between the seal housing 210 and the wear sleeve 240 to protrude from the seal housing 210 in a second axial direction opposite the first axial direction. Incidentally, in FIG. 4 , the downward curved arrow around the rotatable shaft indicates a representative direction of rotation.

[0018] Dust seal 230 may include a radially outward mounting portion 234 coupled to seal housing 210 and a radially inward dust seal lip 236 positioned to seal around wear sleeve 240 at a second axial position. Accordingly, it can be seen that a spacing distance may extend axially between the sealing positions of radially inward main seal lip 226 and radially inward dust seal lip 236. It can also be seen that circumferential seal cavity 250 may extend between main seal 220, dust seal 230, and wear sleeve 240, and in particular, in the illustrated embodiment, is defined by main seal 220, dust seal 230, and wear sleeve 240. Dust seal 230 may have a shorter length than main seal 220. For example, radially inward dust seal lip 236 may have a shorter length than radially inward main seal lip 226.

[0019] Also, in the illustrated embodiment, the seal housing 210 may include an outer housing portion 214 and an inner housing portion 216 that mates with the outer housing portion 214. The outer housing portion 214 and the inner housing portion 216 may be separate components. The outer housing portion 214 may form an L-shape in cross section. Similarly, the inner housing portion 216 may form an L-shape in cross section. A portion of the inner housing portion 216 may be interference-fit with a portion of the outer housing portion 214, as shown in FIG. 4. The main seal 220 and the dust seal 230 may be secured (e.g., clamped, friction-fit, adhesively bonded, etc.) between the outer housing portion 214 and the inner housing portion 216, as shown in FIG. 4. That is, the radially outward mounting portion 224 of the main seal 220 and the radially outward mounting portion 234 of the dust seal 230 may be secured (e.g., clamped, friction-fit, adhesively bonded, etc.) between the outer housing portion 214 and the inner housing portion 216, as shown in FIG. 4.

[0020] 4, the wear sleeve 240 can include at least one channel 242. In the illustrated embodiment, the wear sleeve 240 includes two channels 242, but embodiments of the present disclosure are not so limited. For example, the wear sleeve 240 can include three channels 242 or four channels 242. The channels 242 can be evenly spaced around the circumference of the wear sleeve 240. As an example, in the case of two channels 242, the channels 242 can be spaced 180 degrees apart from each other, e.g., at the top and bottom of the wear sleeve 240, as shown in FIG. 4.

[0021] The opening or hole 244 may be at a second end of the channel 242, opposite the end or edge of the channel 242, and may extend from the second end of the channel 242 to the circumferential seal cavity 250, as shown in FIG. 4 . In one or more embodiments, the opening 244 may extend radially outward from the channel 242, i.e., at a 90-degree angle. Here, the opening 244 may be the only opening extending from the channel 242 to the circumferential seal cavity 250. The channel 242 may have a cross-section that is larger than the cross-section of the opening 244, one or both of which may be uniform. For example, as shown in the end or front views of FIG. 4 , the width of the channel 242, which may be rectangular in end / front view, may be larger than the width of the opening 244, which may also be rectangular in end / front view (but has a length that is offset 90 degrees relative to the width of the channel 242).

[0022] Optionally, channel 242 may have a stub 243 at its second end, where stub 243 may extend axially beyond opening 244. Thus, if external material (e.g., dust) enters channel 242, the external material may pass past opening 244 and into stub 243, preventing or minimizing entry into opening 244.

[0023] With further reference to FIG. 4 , the top, bottom, sides, and ends of each channel 242 may be defined by a respective wall of the wear sleeve 240. Furthermore, each channel 242 may extend from an end or edge of the wear sleeve 240 and may terminate along the length of the wear sleeve 240. The edge at which the channel 242 begins may face axially outward, toward the surrounding environment of the rotatable shaft assembly 14 or portion thereof, such as the housing 12. As shown in FIG. 4 , the channel 242 may terminate in alignment with the circumferential seal cavity 250 in the radially outward direction. According to one or more embodiments, at least the opening 244 may be aligned with the circumferential seal cavity 250 in the radially outward direction. Optionally, the end of the stub 243, which may define the end of the channel 242, may overlap the circumferential seal cavity 250 in the radially outward direction.

[0024] Channels 242 and openings 244 may be referred to or considered as vents. Thus, the above-described wear sleeve 240 may be considered a primary wear sleeve and, in this embodiment, may include or house multiple vents in the form of channels 242 and openings 244, respectively. During operation of machine 10, and particularly during rotation of rotatable shaft 16, e.g., at relatively high speeds, air may pass through channels 242 and openings 244, entering through an inlet of channel 242, which may be axially outward of radially inward-facing dust seal lip 236 of dust seal 230, exiting through openings 244, and into circumferential seal cavity 250, as shown by the arrows in the blown-up portion of FIG. 4 . Thus, vents may be considered to extend from circumferential seal cavity 250 to the exterior of seal assembly 200, i.e., at least outside seal assembly 200 and rotatable shaft 16. Such venting created by channels 242 and openings 244 can prevent or minimize the formation of a vacuum at the junction between main seal 220 and dust seal 230, i.e., within circumferential seal cavity 250. That is, the venting effect created by channels 242 and openings 244 can prevent or minimize the formation or likelihood of a vacuum at the junction between main seal 220 and dust seal 230, i.e., within circumferential seal cavity 250.

[0025] 5, it should be noted that the orientation of channel 242 can be set to control the air inflow velocity into channel 242 and therefore the vent formed by channel 242 and opening 244. In FIG. 5, the downward arrow represents the direction of rotation of rotatable shaft 16. Here, the top box represents a configuration in which channel 242 is oriented perpendicular to the direction of rotation of rotatable shaft 16, i.e., the tilt angle W is equal to 90 degrees, the middle box represents a configuration in which channel 242 is oriented at an angle W greater than 90 degrees (e.g., 110 degrees or 120 degrees), and the bottom box represents a configuration in which channel 242 is oriented at an angle W less than 90 degrees (e.g., 70 degrees or 80 degrees). In other words, the angle W between the channel length axis of the channel 242 and the orbit of the circumferential motion of the rotatable shaft 16 is 90 degrees in the top box, the angle W between the channel length axis of the channel 242 and the orbit of the circumferential motion of the rotatable shaft 16 is greater than 90 degrees (e.g., 110 degrees or 120 degrees) in the middle box, and the angle W between the channel length axis of the channel 242 and the orbit of the circumferential motion of the rotatable shaft 16 is less than 90 degrees (e.g., 70 degrees or 80 degrees) in the bottom box. In the case of the top box, the configuration can provide both dust exclusion and ventilation capabilities (e.g., optimized for both), while the middle box and bottom box can provide enhanced dust exclusion and enhanced forced air intake, respectively. More generally, a higher tilt angle can result in more dust exclusion or air intake, depending on the direction of the tilt angle. The opening 244 can be located at the center of the width of the channel 242, as shown in the top-down view of FIG. 5 .

[0026] Referring now to FIG. 6, FIG. 6 illustrates another seal assembly 300 according to one or more embodiments of the present disclosure. In particular, rather than the channels 242 and openings 246 forming vents, the channels 246 may be implemented. Here, the channels 246 may be formed completely or partially within a secondary sleeve 245 that surrounds the wear sleeve 240 (which, as discussed above, may be considered the primary wear sleeve). According to one or more embodiments, the channels 246 may be formed completely by the secondary sleeve 245. That is, the top, bottom, and sides of each channel 246 may be defined by the respective walls of the secondary sleeve 245. Alternatively, the outer diameter of the wear sleeve 240 may define the bottom or floor of each channel 246.

[0027] Dust seal 230 may be shorter in length than main seal 220. For example, radially inwardly directed dust seal lip 236 may be shorter in length than radially inwardly directed main seal lip 226. Furthermore, in view of secondary sleeve 245 on the outer surface of wear sleeve 240, dust seal 230 may be shorter than dust seal 230 of seal assembly 200 in the embodiment of Figure 4 described above. That is, radially inwardly directed dust seal lip 236 of seal assembly 300 in the embodiment of Figure 6 may be shorter than radially inwardly directed dust seal lip 236 of seal assembly 300 in the embodiment of Figure 4.

[0028] In the illustrated embodiment, two channels 246 are implemented, although embodiments of the present disclosure are not so limited. For example, three or four channels 246 can be implemented. The channels 246 may be evenly spaced around the circumference of the auxiliary sleeve 245. As an example, in the case of two channels 246, the channels 246 may be spaced 180 degrees apart from each other, for example, at the top and bottom of the auxiliary sleeve 245, as shown in FIG. 6.

[0029] As shown in the end or front view of Figure 6, the channel 246 may be rectangular in end or front view. Also, as shown in Figure 6, the channel 246 may extend straight from the surroundings of the rotatable shaft assembly 14 or a portion thereof, such as the housing 12, to the circumferential seal cavity 250. The wear sleeve 240 may have a straight, e.g., rectangular, axial or side profile. Also, the main seal 220 and the dust seal 230 may be curved in axial profile.

[0030] As mentioned above, channel 246 may be referred to or considered as a vent. Thus, during operation of machine 10, particularly during rotation of rotatable shaft 16, e.g., at relatively high speeds, air may pass through channel 246, entering at an inlet of channel 246, which may be axially outward of radially inward-facing dust seal lip 236 of dust seal 230, and exiting channel 246 into circumferential seal cavity 250, as indicated by the arrows in the enlarged view portion of FIG. 6 . Thus, a vent may be considered to extend from circumferential seal cavity 250 to the exterior of seal assembly 200, i.e., at least outside seal assembly 200 and rotatable shaft 16. Such a vent formed by channel 246 may prevent or minimize vacuum formation at the junction between main seal 220 and dust seal 230, i.e., within circumferential seal cavity 250. That is, the venting effect created by the channels 246 can prevent or minimize the possibility of a vacuum forming at the junction between the main seal 220 and the dust seal 230 , i.e., within the circumferential seal cavity 250 .

[0031] 7, it should be noted that the orientation of the channels 246 can be set to control the air inflow velocity into the channels 246. In FIG. 7, the downward arrow represents the direction of rotation of the rotatable shaft 16. Here, the top box represents a configuration in which the channels 246 are oriented perpendicular to the direction of rotation of the rotatable shaft 16, i.e., the tilt angle W is equal to 90 degrees, the middle box represents a configuration in which the channels 246 are oriented at an angle W greater than 90 degrees (e.g., 110 degrees or 120 degrees), and the bottom box represents a configuration in which the channels 246 are oriented at an angle W less than 90 degrees (e.g., 70 degrees or 80 degrees). In other words, the angle W between the channel length axis of the channel 246 and the orbit of the circumferential motion of the rotatable shaft 16 is 90 degrees in the top box, the angle W between the channel length axis of the channel 246 and the orbit of the circumferential motion of the rotatable shaft 16 is greater than 90 degrees (e.g., 110 degrees or 120 degrees) in the middle box, and the angle W between the channel length axis of the channel 246 and the orbit of the circumferential motion of the rotatable shaft 16 is less than 90 degrees (e.g., 70 degrees or 80 degrees) in the bottom box. In the case of the top box, the configuration can provide both dust exclusion and ventilation capabilities (e.g., both optimized), while the middle box and bottom box can provide enhanced dust exclusion and enhanced forced air intake, respectively. More generally, a greater tilt angle can result in more dust exclusion or air intake, depending on the direction of the tilt angle.

[0032] Referring now to FIG. 8 , FIG. 8 illustrates another seal assembly 400 according to one or more embodiments of the present disclosure. In particular, instead of a purely cylindrical wear sleeve, the seal assembly 400 may have a wear sleeve 430 with a curved axial longitudinal profile. For example, FIG. 8 illustrates (in a side or external view) a wear sleeve 430 that is curved to form a J-shape. Here, the wear sleeve 430 may have a radially inward mounting portion 434 for mounting the wear sleeve 430 to the rotatable shaft 16 and a radially outward dust seal lip 436 that can provide an axial load against the curved portion of the main seal 420. The seal assembly 400 may also include a main seal 420 that may be curved, which may be disposed within the wear sleeve 430, as shown in FIG. 8 . In this embodiment, the wear sleeve 430 may be operable or function as a dust seal for dust protection.

[0033] The wear sleeve 430 may also include channels 446. In the illustrated embodiment, the wear sleeve 430 includes two channels 446, but embodiments of the present disclosure are not so limited. For example, the wear sleeve 430 may include three channels 446 or four channels 446. The channels 446 may be evenly spaced around the circumference of the wear sleeve 430. As an example, in the case of two channels 446, the channels 446 may be spaced 180 degrees apart from each other, for example, at the top and bottom of the wear sleeve 430, as shown in FIG. 8.

[0034] The opening or hole 444 may be at a second end of the channel 446 opposite the end or edge of the channel 446, for example, extending from the second end portion of the channel 446 to the circumferential seal cavity 250, as shown in FIG. 8 . According to one or more embodiments, the opening 444 may extend radially outward from the channel 446, i.e., at a 90-degree angle. Here, the opening 444 may be the only opening extending from the channel 446 to the circumferential seal cavity 250. Optionally, the channel 446 may have a stub at its second end. The stub may extend radially beyond the opening 444. Thus, if external material (e.g., dust) enters the channel 446, the external material may pass past the opening 444 and into the stub, preventing or minimizing entry into the opening 444.

[0035] With further reference to FIG. 8 , the top, bottom, sides, and ends of each channel 446 may be defined by a respective wall of the wear sleeve 430. Furthermore, each channel 446 may extend from an end or edge of the wear sleeve 430 and may terminate along the length of the wear sleeve 430. The edge from which the channel 446 begins may face radially outward, toward the surrounding environment of the rotatable shaft assembly 14 or portion thereof, such as the housing 12. As shown in FIG. 8 , the channel 446 may terminate in axial alignment with the circumferential seal cavity 250. According to one or more embodiments, at least the opening 444 may be axially aligned with the circumferential seal cavity 250. Optionally, the end of a stub, which may define the end of the channel 446, may axially overlap the circumferential seal cavity 250.

[0036] Channels 446 and openings 444 may be referred to or considered as vents. Thus, wear sleeve 430, which may be considered a primary wear sleeve, in this embodiment may include or house multiple vents in the form of channels 446 and openings 444, respectively. During operation of machine 10, and particularly during rotation of rotatable shaft 16, e.g., at relatively high speeds, air may pass through channels 446 and openings 444, entering through inlets in channels 446 and exiting through openings 444 into circumferential seal cavity 250, as shown by the arrows in the enlarged view portion of FIG. 8 . Thus, vents may be considered to extend from circumferential seal cavity 250 to the exterior of seal assembly 400, i.e., at least outside seal assembly 400 and rotatable shaft 16. Such vents formed by channels 446 and openings 444 may prevent or minimize vacuum formation at the junction between wear sleeve 430 and main seal 420, i.e., within circumferential seal cavity 250. That is, the venting effect created by channels 446 and openings 444 can prevent or minimize the formation or potential for a vacuum at the junction between main seal 420 and wear sleeve 430, i.e., within circumferential seal cavity 250. Thus, channels 446 introduced into wear sleeve 430 can be such that channels 446 are in direct contact with the dust lip, in which case wear sleeve 430 also acts as a dust lip. Thus, in addition to preventing or minimizing vacuum formation at the junction between wear sleeve 430 and main seal 420, wear sleeve 430 can also act as a dust lip and provide dust protection.

[0037] 9, it should be noted that the orientation of channel 446 can be set to control the air inflow velocity into channel 446 and therefore the vent formed by channel 446 and opening 444. In FIG. 5, the right arrow represents the direction of rotation of rotatable shaft 16. Here, the top box represents a configuration in which channel 446 is oriented perpendicular to the direction of rotation of rotatable shaft 16, i.e., the tilt angle W is equal to 90 degrees, the middle box represents a configuration in which channel 446 is oriented at an angle W greater than 90 degrees (e.g., 110 degrees or 120 degrees), and the bottom box represents a configuration in which channel 446 is oriented at an angle W less than 90 degrees (e.g., 70 degrees or 80 degrees). In other words, the angle W between the channel length axis of the channel 446 and the orbit of the circumferential motion of the rotatable shaft 16 is 90 degrees in the top box, the angle W between the channel length axis of the channel 446 and the orbit of the circumferential motion of the rotatable shaft 16 is greater than 90 degrees (e.g., 110 degrees or 120 degrees) in the middle box, and the angle W between the channel length axis of the channel 446 and the orbit of the circumferential motion of the rotatable shaft 16 is less than 90 degrees (e.g., 70 degrees or 80 degrees) in the bottom box. In the case of the top box, the configuration can provide both dust exclusion and ventilation capabilities (e.g., optimized for both), while the middle box and bottom box can provide enhanced dust exclusion and enhanced forced air intake, respectively. More generally, a higher tilt angle can result in more dust exclusion or air intake, depending on the direction of the tilt angle. The opening 444 can be located at the center of the width of the channel 446, as shown in the top-down view of FIG. 9 . [Industrial Applicability]

[0038] As discussed above, embodiments of the present disclosure include dynamically vented crankshaft seals and systems and methods thereof.

[0039] As mentioned above, crankshaft seals can be susceptible to carbonization of hydrocarbon-based lubricants, which can mold or cut into the contact joint of the sealing main lip, potentially made of PTFE, leading to contamination of the pump spiral groove. The rate of carbonization increases with the speed of the rotating shaft, the radial load on the sealing lip, and the temperature and aging of the lubricant. High loads, speeds, and temperatures can lead to the buildup of heat generated by sliding friction between the static sealing lip and the rotating element. The lubricant can begin to burn and form carbon debris if the temperature of the sliding contact joint exceeds its flash point. Carbon debris can gradually accumulate in the pump groove and degrade pump performance to the point of causing external leakage. Increased frictional heating can also be exacerbated by vacuum formation at the joint between the main lip and the dust lip, which is inherently designed to prevent external debris from entering the main sealing joint. The stability and strength of the negative pressure at the joint area can be highly dependent on the dust lip design. High negative pressure can cause a lack of airflow through the main lip spiral grooves, which helps cool the contact joint, and increases the radial load due to increased bending of the main lip towards the joint.

[0040] In view of the foregoing, seal assemblies according to embodiments of the present disclosure, such as seal assembly 200, seal assembly 201, seal assembly 300, and seal assembly 400, may have unique structures for lubrication and sealing around rotatable shaft 16 and for debris exclusion, as well as for preventing or minimizing vacuum formation between the main lip and dust lip of the seal assembly. In particular, the seal assemblies may implement a vent (or multiple vents) to prevent or minimize vacuum formation between the main lip and dust lip of the seal assembly.

[0041] Thus, embodiments of the present disclosure may implement a dynamically vented crankshaft seal. Dynamic venting may include, for example, air passages in the rotating wear sleeve, which may primarily mitigate negative pressure buildup in the bonded area. The aforementioned channels 242 / openings 244 for seal assembly 200, channels 242 for seal assembly 300, and channels 446 / openings 44 for seal assembly 400 may each represent such air passages for ventilation.

[0042] Rapid angular movement of the air passage can prevent or minimize dust ingestion. The air passage can include an elongated channel with an open side facing toward the ID (inner diameter) surface of the wear sleeve (OD) for a crankshaft seal with both a dust and main lip that radially contacts the sleeve. According to one or more embodiments, the channel, e.g., channel 242, can extend axially from the air-facing edge of the sleeve to the location of the bonding area. In such an embodiment, a through-hole, e.g., opening 244, can radially connect the channel to the bonding space. A variation can be to cut a centrally directed channel into a secondary sleeve that is press-fit onto the wear sleeve, as described above for seal assembly 300.

[0043] The channel length may be equal to the axial width of the auxiliary sleeve, and the channel is attached to engage only with the dust lip without touching the sealing main lip. The open side of the channel may face toward the engine. Additionally, a channel included on the engine-facing side of the sleeve flange may contact the dust lip. The channel may extend longitudinally from the outer edge of the flange toward the bonding area, which may pass through the line of contact with the dust lip. The angle (w) between the channel length axis and the trajectory of circumferential motion may be varied to adjust air intake and dust removal. When the channel is oriented perpendicular to the direction of rotation of the rotatable shaft 16 (i.e., the inclination angle W is equal to 90 degrees), the configuration can provide both dust removal and ventilation capabilities (e.g., optimizing both). When the channel is oriented at an angle W greater than 90 degrees (e.g., 110 degrees or 120 degrees), the configuration can provide enhanced dust removal. When the channel is oriented at an angle W less than 90 degrees (e.g., 70 degrees or 80 degrees), the configuration can provide enhanced forced air intake. According to one or more embodiments, the orientation of all of the channels per seal assembly may be the same. Alternatively, the orientation of at least one of the channels may be different from the orientation of one or more other channels.

[0044] Embodiments of the disclosed subject matter can also be described according to the following parenthetical statements.

[0045] (1) A rotatable shaft assembly comprising: a rotatable shaft defining a shaft rotation axis; a wear sleeve surrounding the rotatable shaft and attached directly to the rotatable shaft; and a seal assembly surrounding the rotatable shaft, the seal assembly comprising: a housing; a main seal attached to the housing, the main seal including a mounting portion and a main seal lip, the main seal being curved in a side elevational view of the seal assembly; a dust seal having a mounting portion; and a plurality of vent holes spaced circumferentially from one another around the seal assembly, each of the vent holes extending from an exterior of the seal assembly to a circumferential seal cavity between the main seal and the dust seal to prevent or minimize vacuum formation within the circumferential seal cavity. (2) A rotatable shaft assembly as described in (1), wherein the wear sleeve includes, as each of the vents, a channel and an opening leading from the channel to the circumferential seal cavity. (3) A rotatable shaft assembly as described in (1) or (2), wherein the openings extend from the channel at 90 degrees to each of the vents. (4) A rotatable shaft assembly according to any one of (1) to (3), wherein the angle between the channel length axis and the orbit of the circumferential motion is 90 degrees. (5) A rotatable shaft assembly according to any one of (1) to (4), wherein the angle between the channel length axis and the orbit of the circumferential motion is an acute angle or an obtuse angle. (6) A rotatable shaft assembly described in any one of (1) to (5), wherein the wear sleeve is flat in a longitudinal side view of the seal assembly or is purely cylindrical in a side view of the seal assembly. (7) A rotatable shaft assembly according to any one of (1) to (6), wherein the wear sleeve is curved in a longitudinal side view of the seal assembly. (8) A rotatable shaft assembly according to any one of (1) to (7), wherein the wear sleeve is a dust seal. (9) A rotatable shaft assembly according to any one of (1) to (8), wherein the vent is formed entirely within or by the wear sleeve. (10) A rotatable shaft assembly according to any one of (1) to (9), further comprising an auxiliary sleeve surrounding the wear sleeve, the ventilation hole being formed in or by the auxiliary sleeve. (11) A method including: providing a wear sleeve surrounding a rotatable shaft; and providing a seal assembly surrounding the rotatable shaft, the seal assembly including: a housing; a main seal attached to the housing, the main seal including a mounting portion and a main seal lip, the main seal being curved in a side elevational view of the seal assembly; a dust seal having a mounting portion; and a plurality of vents spaced circumferentially from one another around the seal assembly, each of the vents formed by a channel, each of the vents extending from an exterior of the seal assembly to a circumferential seal cavity between the main seal and the dust seal to prevent or minimize vacuum formation within the circumferential seal cavity, and an angle between a channel length axis of the channel and a path of circumferential motion of the rotatable shaft is 90 degrees, an acute angle, or an obtuse angle relative to each of the channels. (12) The method of (11), further comprising controlling the rotatable shaft to rotate according to a circular motion path, wherein the rotation of the rotatable shaft causes air to pass through the plurality of vents. (13) The method of (11) or (12), wherein the wear sleeve is a dust seal and the wear sleeve is part of a seal assembly. (14) The method of any one of (11) to (13), wherein the vent is formed entirely within the wear sleeve. (15) A rotatable shaft assembly according to any one of (11) to (14), further comprising providing an auxiliary sleeve surrounding the wear sleeve, wherein the ventilation hole is formed entirely within or by the auxiliary sleeve. (16) A seal assembly comprising a wear sleeve, a main seal, a dust seal, and a plurality of circumferentially spaced vents, each of the vents being formed by at least a channel, each of the vents extending from a first side of the seal assembly between the main seal and the dust seal, and an angle between a channel length axis of the channel and a path of circumferential motion of the channel being 90 degrees, an acute angle, or an obtuse angle for each of the channels. (17) The seal assembly of (16), wherein the wear sleeve is a dust seal and the wear sleeve is part of the seal assembly. (18) The seal assembly of (16) or (17), wherein the vent is formed entirely within or by the wear sleeve. (19) A seal assembly according to any one of (16) to (18), further comprising an auxiliary sleeve, the vent hole being formed within or by the auxiliary sleeve. (16) A seal assembly according to any one of (16) to (19), wherein the wear sleeve has, for each vent hole, a channel and an opening leading from the channel to between the main seal and the dust seal.

[0046] It should be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. That is, unless expressly specified otherwise, the terms "a," "an," etc., as used herein, mean "one or more." The term "at least one," when used following a list of one or more items (e.g., "at least one of A and B," or "one or more of A and B"), shall be interpreted to mean one item selected from the listed items (A or B), or any combination of two or more of the listed items (A and B; A, A and B; A, B and B), unless otherwise indicated herein or clearly contradicted by context. Similarly, the term "or" as used herein refers to any possible permutation of a set of items. For example, the phrase "A, B, or C" refers to at least one of A, B, and C, or any combination thereof, such as a plurality of any of the items: A; B; C; A and B; A and C; B and C; A, B, and C; or A and A; B, B, and C; A, A, B, C, and C, etc.

[0047] Furthermore, it should be understood that terms such as "left," "right," "top," "bottom," "front," "back," "side," "height," "length," "width," "top," "bottom," "inner," "outer," "internal," "external," and the like that may be used herein merely indicate points of reference and do not limit embodiments of the presently disclosed subject matter to any particular orientation or configuration. Furthermore, terms such as "first," "second," and "third" merely identify one of multiple parts, components, points of reference, operations, and / or functions described herein and similarly do not necessarily limit embodiments of the disclosed subject matter to any particular configuration or orientation. As used herein, a top view may be considered a side view.

[0048] While aspects of the present disclosure have been particularly shown and described with reference to the above embodiments, it will be understood by those skilled in the art that various additional embodiments may be envisioned by modification of the disclosed machines, assemblies, systems, and methods without departing from the spirit and scope of the disclosed subject matter. Such embodiments are to be understood to fall within the scope of the present disclosure as determined by the claims and any equivalents thereof.

Claims

1. A rotatable shaft assembly (14) comprising: a rotatable shaft (16) defining a shaft rotation axis; a wear sleeve (240, 430) surrounding the rotatable shaft (16) and attached directly to the rotatable shaft (16); a seal assembly (200, 201, 300, 400) surrounding the rotatable shaft (16); The seal assembly (200, 201, 300, 400) comprises: a housing (210); a main seal (220, 420) attached to the housing, the main seal (220, 420) including a mounting portion (224) and a main seal lip (226), the main seal (220, 420) being curved in a side external view of the seal assembly (200, 201, 300, 400); a dust seal (230, 430) having an attachment portion; a plurality of vents (242 / 244, 246, 444 / 446) circumferentially spaced apart from one another around the seal assembly (200, 201, 300, 400); Each of the vents (242 / 244, 246, 444 / 446) extends from the exterior of the seal assembly (200, 201, 300, 400) to a circumferential seal cavity (250) between the main seal (220, 420) and the dust seal (230, 430), preventing or minimizing vacuum formation within the circumferential seal cavity (250).

2. 2. The rotatable shaft assembly of claim 1, wherein the wear sleeve comprises, as each of the vents, a channel and an opening leading from the channel to the circumferential seal cavity.

3. The rotatable shaft assembly of claim 2, wherein the openings (244, 444) extend from the channel (242, 446) at 90 degrees relative to each of the vents (242 / 244, 444 / 446).

4. 2. The rotatable shaft assembly of claim 1, wherein the angle (W) between the channel length axis and the path of circumferential motion is 90 degrees.

5. 2. The rotatable shaft assembly of claim 1, wherein the angle (W) between the channel length axis and the path of circumferential motion is an acute or obtuse angle.

6. The rotatable shaft assembly of claim 1, wherein the wear sleeve (240) is purely cylindrical in the side elevational view of the seal assembly (200, 201, 300).

7. The rotatable shaft assembly of claim 1, wherein the wear sleeve (430) is curved in a longitudinal side elevational view of the seal assembly (400).

8. The rotatable shaft assembly of claim 7, wherein the wear sleeve (430) is the dust seal (430), and the wear sleeve (430) is part of the seal assembly (400).

9. The rotatable shaft assembly of claim 1 , wherein the vent (242 / 244, 444 / 446) is formed entirely within the wear sleeve.

10. 2. The rotatable shaft assembly of claim 1, further comprising a secondary sleeve (245) surrounding the wear sleeve (240), the vent (246) being formed in the secondary sleeve (245), and the secondary sleeve (245) being directly attached to the wear sleeve (240).

11. A seal assembly (200, 201, 300, 400) comprising: a wear sleeve (240, 245, 430); A main seal (220, 420), Dust seal (230, 430); a plurality of vents (242 / 244, 246, 444 / 446) circumferentially spaced apart from one another, each vent (242 / 244, 246, 444 / 446) being defined by at least a channel (242, 246, 446); each of the vents (242 / 244, 246, 444 / 446) extends from a first side of the seal assembly (200, 201, 300, 400) between the main seal (220, 420) and the dust seal (230, 430); A seal assembly wherein an angle (W) between the channel length axis and the orbit of circumferential motion of said channels (242, 246, 446) is 90 degrees, an acute angle, or an obtuse angle for each of said channels (242, 246, 446).

12. The seal assembly of claim 11, wherein the wear sleeve (430) is the dust seal (430), and the wear sleeve (430) is part of the seal assembly (400).

13. The seal assembly of claim 11 , wherein the vent (242 / 244, 246, 444 / 446) is formed entirely by the wear sleeve.

14. The seal assembly of claim 11, further comprising a secondary sleeve (245), the vent (246) being defined by the secondary sleeve (245).

15. 12. The seal assembly of claim 11, wherein the wear sleeve comprises, for each of the vent holes, the channel and an opening leading from the channel to between the main seal and the dust seal.

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