LOW TORQUE RAILWAY WHEEL HUB BEARING SEAL

FIELD OF THE INVENTION

The invention relates to bearing seals for heavy vehicles in general, and to a low torque railway wheel hub bearing seal in particular. The seal is a two part seal with non-contacting radial lips and contacting wiper lips for improved sealing performance at lower torque.

BACKGROUND AND PRIOR ART

Bearings are amongst the most important components of any moving vehicle. Particularly for the rolling stock, they are vital for their very functioning. It is therefore extremely important to ensure that bearings can function for long periods without any hindrance. Bearing assemblies are typically provided as a self-contained unit. Seals are provided on the bearings to protect them from ingress of water, mud, dust etc, and also to ensure that the lubricant of the bearing does not leak out and is not contaminated. Any of these factors, or their combination, has a direct effect on the life of a bearing. Bearings for railway wheel hubs are provided with seals which can be of low torque and high torque types. The present invention concerns itself with low torque railway hub bearings.

US patent 6,485,185 B1 discloses a seal for use with a tapered roller bearing. The seal is meant for sealing bearing assemblies used in railway vehicles or other similar applications.

This patent discloses a radial lip which is a contact curled radial lip made of PTFE material, a plastic material. The patented seal has three radial lips, out of which one is a contact curled lip. Wiper lip of the seal has a face contact with metal part. The contour of the metal part of the patented seal is straight. Also, the seal has no grease retarding lip.

There is no special contour provided in the seal of this patent which ensures followability of radial lips at variable hub speeds.

US patent 6,845,986 B2 discloses a unitized seal assembly for use with roller or ball bearing assemblies which are meant primarily for railcars. The seal has only non-contact sealing lips, which are designed as blocks. The patent shows non-contacting wiper lips. The shape of metal part of the patent is straight. In this patent also, no grease retarding lip has been provided. The disclosed seal has no elastomeric deflector for retarding flow of mud or water into the seal.

US patent application 2009/127795 (A1) discloses a non-contact labyrinth seal assembly for roller bearings. This seal is also intended for use with bearings for railway wheel hubs.
The seal disclosed in this patent has a totally non-contact sealing lip design. The sealing lips are designed as a block with stepped profile. The seal disclosed in this patent has. a non-contact grease retarding lip which is narrow. There is no contacting wiper lip in this seal.
An elastomeric deflector has been provided, but no special contour to effectively prevent ingress of mud, water and dust into the hub is provided.

OBJECTIVES OF THE INVENTION

The primary objective of the present invention therefore is to provide a seal for hub bearing whose sealing lips are flexible and produce low frictional torque.

Another objective of the invention is to provide a seal which has effective non-contact sealing of the lubricant.

Yet another objective of the invention is to provide a seal which has flexible non-contact radial lips to ensure that there is no frictional torque due to the hub rotation.

Another objective of the invention is to provide a seal which has angular non-contact lips made from a rubber polymer for effectively deflecting the grease ensuring a non-contact sealing as well as giving a low frictional torque.

Yet another objective of the invention is to provide a seal which has a wiper lip having radial contact with metal part to give reduced frictional torque and improved sealing ability.

Another objective of the invention is to provide a seal which has elastomeric deflector to prevent ingress of mud, water and dust into the hub.

Yet another objective is to provide a seal which has special contour on a first metal part for greater followability at variable hub speeds.

SUMMARY OF THE INVENTION

A low torque railway wheel hub bearing seal comprises a first metal part and a second metal part, which are sheet metal pressed components. They form a unitized construction when assembled, which is the seal. The first metal part is moulded with a low friction rubber polymer material, which also forms the sealing lips to make them flexible. The outer part of the first metal part is coated with a bore tight sealant to ensure micro sealing on the hub. The inner portion of the second metal part is coated with the same sealant to ensure micro sealing with the collar in the hub. Each of the sealing lips has been designed with an optimized contour profile. An elastomeric deflector is provided in the form of a sealing lip to retard direct flow of mud or water. The seal has three non-contact radial lips, one non-contact grease retardant lip and a positive contacting wiper lip.

The optimized contour profile and the flexibility of the sealing lips result in appreciable reduction of the torque of the seal by 50% as compared to garter spring construction seals for similar application.
The positive contacting wiper lip effects sealing of grease from the hub side and ensures there is no ingress of water or mud into the seal, thereby ensuring enhanced sealing ability of external contaminants into the hub.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING
Fig.1 shows a cross sectional view of the hub bearing seal according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in an exemplary embodiment as depicted in the accompanying drawing. There can however be other embodiments of the same invention within the same inventive concept, all of which are deemed covered by the following description. The accompanying claims forming a part of this specification generally define the invention, but are not to be construed as limiting.

The terms "outer", "inner", "top", "bottom", "lower", "upper" are used with respect to the orientation of the seal as used.

As seen in Fig.1, the low torque railway wheel hub bearing seal according to the invention consists of first and second metal parts (4, 8) which are assembled to form a unitized construction, which is the seal. Both the first and second metal parts (4, 8) are made as sheet metal pressed components. First metal part (4) is moulded with a low friction rubber polymer material which also forms the sealing lips (1, 5, 7, 10, 11 and 12). First metal part (4) has been provided with a shape (14) on its internal side which gives effective anchorage to the seal and ensures rigidity of the seal during assembly. This contour (14) also ensures followability of the radial lips at variable hub speeds. The outer face of the first metal part (4) is coated with a bore tight sealant (2, 3) to ensure micro sealing on the hub. The inner portion of second metal part (8) is also coated with this sealant (9) to ensure micro sealing with the collar in the hub. Second metal part (8) has been given a special curved profile (15) so that it effectively retains the grease in the seal cavity, enabling effective sealing. The curvature of said profile (15) can vary in other embodiments of the invention, which are included in the present invention. It also has a positive contour (6) on the outer side (environmental side) to prevent any direct ingress of mud and water. A positive locking on the top face (13) is also provided for better grease retention in the hub bearing.

A sealing lip (1) is provided to prevent the flow of grease to the seal lips. This sealing lip is a non contacting deflector which is provided with a special contour to improve the ability of the seal to prevent direct grease flow onto the other seal lips. Three non-contact radial sealing lips (10,11, 12) are provided for the sealing of grease in the hub. The orientation of these lips is designed in such a way that it helps in restricting the ingress of mud, water and dust through the seal.

A positive contacting wiper lip (7) helps in effective sealing of grease from the hub side and also ensures that there is no ingress of water or mud into the seal. This positive contacting wiper lip (7) is the effective feature in ensuring enhanced sealing ability of external contaminants (water, mud, dust) into the hub which are the greatest hazards for the bearing.

An additional elastomeric deflector in the form of sealing lip (5) is provided to retard direct flow of any mud or water onto the seal which can deteriorate the bearing life. In other embodiments of the same invention, the length of this lip can vary from what is shown in Fig.1.

Sealing lips (10,11,12) are radial angular lips made from a rubber polymer, which renders them flexible while providing effective sealing. This also results in a low frictional torque. Angular lips (11, 12) help in deflecting the grease effectively while ensuring a non-contact sealing. Non-contact radial lips (10, 11, 12) ensure no frictional torque during the hub rotation. The positive contacting wiper lip (7) ensures reduced frictional torque with improved sealing ability.

Each of the sealing lips (1, 5, 7, 10, 11, 12) has been provided with an optimized contour profile to ensure that the torque is maintained at minimum level. The hub bearing seal according to the present invention ensures a reduction in torque by 50% as compared to. garter spring construction seals for similar application. The seal also has a novel feature of the elastomeric deflector (5), which ensures that there is no ingress of water and mud into the seal which damage the hub bearing due to seal failure.

A combination of the sealing lip profile design, provision of elastomeric deflector and use of a rubber polymer material contributes to the low torque generated by the seal and also ensures the sealing of external contaminants like water, mud and dust.

This hub bearing seal as described above ensures an improved performance in sealing at a lower torque.
The seal has angular lips (11, 12) made from a rubber polymer which help in deflecting the grease effectively ensuring a non-contact sealing as well as giving a low frictional torque, while ensuring effective sealing.

It has three radial slips as flexible non-contact radial slips (10, 11,12) which ensure that there is no frictional torque due to the hub rotation.
Said wiper lip (7) has a radial contact with metal part. This ensures reduced frictional torque with improved seal ability and sealing of water ingress into the bearing.

The second metal part (8) of the seal has a curved profile (15) which retains the grease in the seal cavity enabling more effective sealing. The curvature of this profile can be different from what is shown in

Fig.1 without affecting its purpose and it falls within the scope of the present invention.

The present invention has provided a grease retarding lip (1) in the seal which provides effective sealing of the grease.

A special contour (14) has been provided in said first metal part (4) in the present design, which ensures followability of radial lips at variable hub speeds. There is no such corresponding feature in the prior art.
In the present invention, the non-contact sealing lips (10, 11,12) are designed as radial angular lips which are flexible and also ensure better grease sealing.
In the present invention, an elastomeric deflector (5) has been provided for retarding flow of mud and water. This elastomeric lip (5) prevents ingress of mud, water and dust into the hub. The length of this deflector can vary without affecting its purpose and it is within the scope of the present invention.

A special contour (14) has been provided in metal part (4) in the present seal, which ensures followability of radial lips at variable hub speeds.

The present invention has been described with reference to a preferred embodiment and drawings for the sake of understanding and not by way of any of limitation and the present invention includes all legitimate developments within the scope of what has been described hereinbefore and claimed in the appended claims.

We claim:

1. A low torque railway wheel hub bearing seal comprising a first metal part (4) and a second metal part (8), which two metal parts are made as sheet metal pressed components and form a unitized construction when assembled; said first metal part (4) is moulded with a low friction rubber polymer material, which material also forms the sealing lips (1, 5, 7, 10, 11 and 12) to make them flexible; the outer part of the said first metal part (4) is coated with a bore tight sealant (2, 3) to ensure micro sealing on the hub; the inner portion of said second metal part (8) is coated with the said bore tight sealant (9) to ensure micro sealing with the collar in the hub, wherein each of the said sealing lips (1, 5, 7, 10, 11, 12) is provided with an optimized contour profile; one of said sealing lips (5) near the side of the seal is an elastomeric deflector provided to retard direct flow of mud or water; sealing lips (10,11 12) are non-contact radial lips; sealing lip (1) near the top face (13) of the seal is a non-contact grease retardant slip and sealing lip (7) near the lower face of the seal is a positive contacting wiper lip.

2. The low torque seal as claimed in claim 1, wherein the said seal has a reduced torque which is 50% as compared to garter spring construction seals for similar application.

3. The low torque seal as claimed in claim 1, wherein said positive contacting wiper lip (7) effects sealing of grease from the hub side and ensures there is no ingress of water or mud into the seal, thereby ensuring enhanced sealing ability of external contaminants into the hub.

4. The low torque seal as claimed in claim 1, wherein said non-contact radial sealing lips (10, 11 12) are angular lips made from a rubber polymer which help in deflecting the grease effectively while ensuring a non-contact sealing.

5. The low torque seal as claimed in claim 1, wherein said positive contacting wiper lip (7) ensures reduced frictional torque with improved sealing ability.

6. The low torque seal as claimed in claim 1, wherein said first metal part (4) has been provided with a shape (14) on its internal side which gives effective anchorage to the seal and ensures rigidity of the seal during assembly and said second metal part (8) has a special curved profile (15) to retain the grease in the seal cavity, enabling effective sealing.

7. The low torque seal as claimed in claims 1 and 6, wherein said second metal part (8) has a positive contour (6) on the outer side (environmental side) to prevent any direct ingress of mud and water.

8. The low torque seal as claimed in any preceding claim, wherein a positive locking is provided on the top face (13) of said seal for better grease retention in the hub bearing.

9. The low torque seal as claimed in claim 1, wherein said sealing lip (1) is a deflector which has a special contour to prevent direct grease flow onto the other seal lips.

10. The low torque seal as claimed in claim 1, wherein said three non-contact radial sealing lips (10, 11, 12) provide sealing of grease in the hub and their orientation restricts ingress of mud, water and dust through the seal.