SE537827C2 - Sealing arrangement for a vehicle for providing an air transfer chamber between an axle and a hub - Google Patents

Abstract

13 ABSTRACT The present disclosure relates to a sealing arrangement for a vehicle forproviding an air transfer Chamber between a shaft and a hub, surrounding theshaft. One of the shaft and the hub is connected to the body of the vehicleand the other to a wheel of the vehicle. The transfer chamber is ring-shaped and confined between the shaft, the hub, and at least a first and a second ring-shaped seal which are axially separated in the axial direction of the shaft. 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc

Description

AWAPATENT ABKontor/HandläggareVäxjö/Magnus Hjalmarsson/MAH Trelleborg Forsheda ABVår referensSE-21060983 SEALING ARRANGEMENT Technical fieldThe present disclosure relates to a sealing arrangment which may be useful in connection with a central tyre inflation, CTI, system.

BackgroundOne example of such an arrangement is illustrated in FR-2874671-B1, where a chamber is formed between two ring-shaped seals which areattached to a rotating wheel, and which each create a sealing function againsta ring shaped sleeve which has an L-shaped cross section. Two such ring-shaped sleeves are provided and an air passage is provided in between thesleeves in order to feed air from a shaft, to which the sleeves are attached,and into the chamber.

One general problem with such arrangement is to provide an improved arrangement.

SummaryThis object is achieved by means of sealing arrangements as defined in the appended claims.

More specifically, the sealing arrangement may then be used in avehicle for providing an air transfer chamber between a shaft and a hubsurrounding the shaft. One of the shaft and the hub is connected to the bodyof the vehicle and the other to a wheel of the vehicle. The transfer chamber isring-shaped and confined between the shaft, the hub, and at least a first anda second ring-shaped seal which are axially separated in the axial direction ofthe shaft. A base ring, is adapted to be attached to the shaft, wherein thebase ring includes means to attach the first and second ring-shaped seals to the base ring, and the base ring includes at least one radial hole adapted to 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icationteXt_MAH.doc provide a passage between an air channel of the shaft and the transferchamber. Such an arrangement may be produced in an efficient way, as thebase ring allows the mounting of a plurality of sealing features, and may beproduced e.g. by injection moulding.

The base ring may be made of a plastic material such as polyamide,and the means for attaching the first and second ring-shaped seals to thebase ring may include a circumferential groove in the base ring. Thearrangement may include at least one further seal, and the ring shaped sealmay be held between the further seal and a shoulder portion in the base ring.

The present disclosure further relates to a sealing arrangement thatmay include first and second ring-shaped seals being made of e.g. ofpolytetraflourethelene, PTFE, which are arranged to be attached to the shaftand have a bent profile, such that, at the outer end, where the seals interactwith an inner surface of the hub, the seals are bent inwards, towards the innerof the transfer chamber. The sealing arrangement may be a cassette seal,comprising an outer sleeve which is intended to be attached to the hub. Thissealing arrangement may comprise a third seal, between the first andseacond seals, dividing the transfer chamber axially into first and secondcompartments.

The present disclosure further relates to a sealing arrangement for avehicle for providing an air transfer chamber between a shaft and a hubsurrounding the shaft, wherein one is connected to the body of the vehicleand the other to a wheel of the vehicle. The transfer chamber is ring-shapedand confined between the shaft, the hub, and at least a first and a secondring-shaped seal which are axially separated in the axial direction of the shaft.A third sealing ring is provided that divides the transfer chamber axially into afirst and a second compartment. This allows the provision of a separatecontrol air channel that may be used e.g. to control a valve in connection withthe wheel.

The arrangement may comprise a base ring, which is attached to theshaft, and the third seal may be placed in a circumferential groove in the basering. The groove may be wider than the width of the third seal, such that an 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc air passage is created to the inner side of the third seal, and a slit may beprovided in the third ring shaped seal facilitating the radia| expansion of theseal.

The present disclosure further re|ates to a sealing arrangement for avehicle for providing an air transfer chamber between a shaft and a hubsurrounding the shaft, wherein one is connected to the body of the vehicleand the other to a wheel of the vehicle, the transfer chamber being ring-shaped and confined between the shaft, the hub, and at least a first and asecond ring-shaped seal, which are attached to the shaft, axially separated inthe axial direction of the shaft. The first and second seals are in moveablecontact with an outer ring shaped sleeve which is arranged to be attached tothe hub. The outer sleeve comprises holes providing an outlet for the transferchamber, wherein the holes are longated in the circumferential direction of thesleeve. This provides a more rigid outer sleeve for a given hole area.

Brief description of the drawinqs Fig 1 shows a front view of a wheel arrangement.

Fig 2 shows a side view with a partial cross section of the arrangementin fig 1, where the location of a sealing structure is indicated.

Fig 3 shows the cross section of fig 2 enlarged.

Fig 4 illustrates schematically the cassette seal of fig 3.

Fig 5 corresponds to fig 4, but with retained cross-section hatchings.

Fig 6 is a front view of a ring shaped seal.

Fig 7 shows in cross-section, a ring shaped seal, such as the one in fig6, when fitted in a groove in a base ring.

Fig 8 corresponds to fig 4, but shows a state where a ring shapedchamber is not pressurized, and the air seals are in a relaxed position.

Detailed descriptionThe present disclosure is related to solutions used in connection with vehicle central tyre inflation, CTl, systems. Such system allow to vary thepressure in a tyre by inflating or deflating a tyre without manually attaching a 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc conduit to the tyre and supplying compressed air or letting air out of the tyrevia a valve. lnstead, the vehicle itself adjusts the pressure in the tyre,automatically or being controlled by an operator.

Varying the tyre pressure can be usefule under certain circumstances.For instance, in a tractor which enters a wet field, it may be useful to lower thetyre pressure to some extent. This flattens the tyres somewhat such that thetractor load is spread over a slightly greater surface, which may reducedriving damage on the field. On the other hand, when subsequently driving ona hard surface such as a road, it may be desired to increase the tyre pressureas this reduces rolling resistance and thus fuel consumption. This can beachieved in a convenient way with a CTl system, where the tyres can be fedwith compressed air from the body of the vehicle, that can be provided with acompressor.

A CTl system requires an air passage between the body of the vehicleand the rotating wheel and this can be accomplished between two seals,confining a ring-shaped chamber space between e.g. an inner shaft and anouter hub.

Fig 1 shows a front view of a wheel arrangement 1, and fig 2 shows aside view with a partial cross section of the arrangement in fig 1, along theindicated line D-D. With reference to figs 1 and 2, the wheel arrangement 1shown can be used e.g. in a dump truck where a planetary gear, not shown,is located in a housing in an area 3, at the end of a fixed shaft 7. The gear isdriven by a rotating drive shaft, not shown, which is connected to the sun gearof the planetary gear. The drive shaft passes through an opening 5 in thefixed shaft 7. The ring gear of the planetary gear is connected to the fixedshaft 7, and a rotating housing 9 to which a wheel and tyre is attached, isconnected to the planet carrier of the planetary gear and is arranged to rotatearound the axis of the fixed shaft being attached thereto by means of at leastone bearing 11.

As can be seen in figs 2 and 3, the arrangement provides a shaftchannel 13 in the fixed shaft 7 and a wheel channel 15 in the rotating housing9 for feeding pressurized air to the tyre (not shown) of the wheel attached to 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc the rotary housing. The shaft channel 13 and the wheel channel 15 areinterconnected by means of a ring shaped Chamber formed by a sealingstructure 17, which will now be described in more detail.

Fig 4 illustrates schematically the cassette or cartridge seal 17 of fig 3.By a cassette seal is meant that the sealing function is provided as acomplete unit, including both a part connected to and being intended to bestationary with the rotating part and a part connected to and being intended tobe stationary with the body of the vehicle. This means that friction betweensealing parts, upon rotation of the rotating house, will occur internally in thecassette rather than against the shaft or the hub themselves. This means thatseal friction will not cause wear on the hub or shaft, and when the cassette isreplaced during maintenance, all items subject to seal wear may be replaced,which improves the long term functionality. The concept of cassette orcartidge seals is well known per se.

The cassette seal includes one part connected to the rotating housingby press-fitting, which part consists of a sheet metal sleeve 21. The sheetmetal sleeve 21 may be made of a carbon steel. This part will rotate with thewheel, while the remainder of the cassette seal will remain stationary with thefixed shaft 7, possibly with the exception of a floating seal ring 23 that will bedescribed later.

A base ring 25 is attached to the fixed shaft 7 and functions as abuilding base for a plurality of sealing features. The base ring surrounds theshaft and may be made of polyamide, such as PA6, optionally reinforced withfibreglass.

From the left to the right in fig 4, the base ring 25, which may be madeof a plastic material, has a ring shaped oil seal 27, which is connected to thebase ring 25 via a first sheet metal frame 29, to which the oil seal may bevulcanized. The oil seal 27 may be urged towards the inner surface of thesheet metal sleeve 21 by means of a spring 31. The oil seal is located on theoil side 33 of the cassette seal and serves to confine the oil or grease of thebearing 11 in a designated space that may optionally also be shared with agear, or another lubricated device. The metal frame 29 which is ring-shaped 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc may be made of a carbon steel, and oil seal 27 may be made of a nitrilerubber, NBR, as one example.

A first ring shaped air seal 35 is provided next, which may be madee.g. of polytetrafluoroethylene, PTFE, and is attached to the base ring 25.This seal may be fitted into a circumferential groove in the base ring and mayfurther be kept in place by the oil seal ring 27 forcing the PTFE seal against ashoulder portion 28 of the base ring. Similarly, a second air seal 37 may beprovided in a circumeferential groove in the base ring 25. The first andsecond air seals 35, 37 run radially from the base ring 25 to the the innersurface of the sheet metal sleeve 21, and thereby define a closed ring shapedspace 39, 41 between each other, the base ring 25, and the sheet metalsleeve 21. At the surface of the sheet metal sleeve 21, the profile air seals 35,37 may be bent inwards, towards the ring shaped space 39, 41. ln this waythe air pressure difference between the overpressure in the closed ringshaped space 39, 41 and the surrounding spaces can be higher for a givenallowed leakage. Further, when the chamber is not pressurized, the air sealsmay be in relaxed position, which is shown in fig 8, where the friction betweenthe air seals and the sleeve 21 is reduced.

A further ring shaped seal 23 can be provided in the ring shaped space39, 41 dividing it axially into a first 39 and a second 41 compartment, as willbe discussed later.

The base ring 25 may further have ring shaped water seal 43, which isconnected to the base ring via a ring shaped second sheet metal frame 45, towhich the water seal may be vulcanized. Similar materials may be used aswith the oil seal 27 and its frame 29. The water seal 43 may also assist inkeeping the second air seal 37 in place. The water seal 43 may be urgedtowards the inner surface of the sheet metal sleeve 21 by means of a furtherspring 47. The water seal 43 is located on a water/dust side 49 of thecassette seal and serves to protect the inner parts of the cassette and thebearing from water and dust that the vehicle can be subjected to when operating in a rough environment. 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc A further ring shaped frame 40 may be provided which is press fittedinto the base ring 25 and provides further seal lips 53, 55 vulcanized thereto.This frame may further present lugs 42, one of which is shown in crosssection. The lugs are spaced apart around the circumference of the frame 40,and serve to position the ring shaped s|eeve 21 correctly to the other parts ofthe arrangement during mounting. The rubber inside of this frame alsoprovides sealing between the base ring 25 and the shaft _ The spring |oaded water seal 43 is primarily meant to stop water fromentering the cassette seal, and is in turn protected from entering dust by anumber ofdust sealing lips 51, 53, 55, placed upstreams relative to thedirection in which dust and water could be expected to enter. ln order to feed pressurized air to the tyre of the rotating housing 9, viathe ring shaped space 39, 41, one or more radial holes 57 are provided in thebase ring 25. These holes are axially aligned with the ring shaped space, andare aligned with a corresponding channel opening (cf. 13 in fig 2) in the fixedshaft 7. O-ring seals 59, 61 may be provided between the base ring 25 andthe fixed shaft 7, axially at either sides of the holes 57. Correspondingly, ahole 63 is provided in the sheet metal s|eeve 21. ln order to achieve a higherstructural strength in the s|eeve 21, it may be preferred to elongate the hole63 along the circumference of the s|eeve, such that the axial extension of thehole can be limited with a maintained hole area. By means of these provisionsan air path 65 is formed from the fixed shaft 7 to the rotating housing 9.

As mentioned, it may be preferred to axially divide the aforementionedring shaped space 39, 41 into a first 39 and a second 41 compartment. Thismay be done by means of a ring shaped seal 23 which is provided floating ina groove 67, extending along the periphery of the base ring 25. The ringshaped seal 23 may be made out of PTFE and may be cut of by a slit 24 (cf.fig 6 showing a front view of the seal 23), such that the seal 23 can expandslightly radially. The slit 24 can be provided in other configurations than theone shown in fig 6.

The groove 67 can be slightly wider than the width of the seal 23, andmay be deeper than the inner diameter of the seal would require to fit in the 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc groove 67. This means that an air connection 69 between the ring shapedspace compartment 41 and the interior of the ring shaped sea| 23 can beformed, which forces the ring to expand, and thereby form a tighter radia| sea|against the s|eeve 21 surface as well as an axial sea| on one side wall 68 ofthe groove, when the compartment 41 is pressurized. This is illustrated in fig7, where arrows indicate the surfaces of the sea| 23 where an overpressure inthe compartment to the right of the sea| 23 has begun to force the sea| 23against the side wall 68, and the ring is about to expand radially towars theouter s|eeve 21 _ Dividing the ring shaped space into two compartments allows to createa secondary air path between the fixed shaft 7 and the rotating housing 9.This may be achieved by means of a second hole 71 in the base ring 25, anda second hole in the sheet metal s|eeve 21 _ The secondary air path may beused e.g. to control a valve in the wheel. For instance, pushing air through thesecond path may open the valve in the rotating housing such that thepressure is lowered in the tyre e.g. by evacuating air through the other,primary air path 65.

The present disclosure is not restricted to the above-describedembodiment, and may be varied and altered in different ways within thescope of the appended claims. For instance, it would be possible to replacethe PTFE seals 35, 37 with the bent profiles with expandable ring shapedseals such as 23. Those seals would then be place in similar grooves. Oneadvantage with this, that could be useful in some applications, is that a firmsea| is only provided when needed, i.e. when the chamber in question ispressurized. On other occasions, the ring shaped sea| is not expanded, andhas a lower or no friction against the s|eeve 21.

Another variation is that the outer part (s|eeve 21) could be fixed andthat the inner part rotates. This would, for instance, be the case when a shaftis fixed to a wheel, and the sealing arrangement is used to convey air from the body of the vehicle to the rotating shaft. 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc The present arrangement may be useful on most vehicles havinginflatable tyres, even if the above examples are shown in the context of heavyvehicles. 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc

Claims (12)

1. A sealing arrangement (17) for a vehicle for providing an airtransfer Chamber between a shaft (7) and a hub (9) surrounding theshaft, wherein one is connected to the body of the vehicle and theother to a wheel of the vehicle, the transfer chamber being ring-shaped and confined between the shaft, the hub, and at least a first(35) and a second (37) ring-shaped seal which are axiallyseparated in the axial direction of the shaft, characterised by a basering (25) which is adapted to be attached to the shaft, wherein thebase ring includes means to attach the first and second ring-shaped seals to the base ring, and the base ring includes at leastone radial hole (57, 71) adapted to provide a passage between anair channel (13) of the shaft and the transfer chamber.

2. A sealing arrangement according to claim 1, wherein the basering is made of a plastic material such as polyamide.

3. A sealing arrangement according to claim 1 or 2, wherein saidmeans for attaching the first and second ring-shaped seals to the base ring includes a circumferential groove in the base ring.

4. A sealing arrangement according to claim 3, wherein saidmeans for attaching the first and second ring-shaped seals to thebase ring further includes a further seal (27, 43), the ring shapedseal (35, 37) being held between the further seal and a shoulder portion (28) in the base ring.

5. A sealing arrangement (17) for a vehicle for providing an airtransfer chamber between a shaft (7) and a hub (9) surrounding the shaft, wherein one is connected to the body of the vehicle and the 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc 11 other to a wheel of the vehicle, the transfer Chamber being ring-shaped and confined between the shaft, the hub, and at least a first(35) and a second (37) ring-shaped seal which are axiallyseparated in the axial direction of the shaft, characterised by saidfirst and second ring-shaped seals being made of e.g. ofpolytetraflourethelene, PTFE, and being arranged to be attached tothe shaft and having a bent profile, such that, at the outer end,where the seals interact with an inner surface of the hub, the sealsare bent inwards, towards the inner of the transfer chamber.

6. A sea|ing arrangement according to claim 5, wherein sea|ingarrangement is a cassette seal, comprising an outer s|eeve (21)which is intended to be attached to the hub.

7. A sea|ing arrangement according to claim 5 or 6, wherein thesea|ing arrangement comprises a third seal (23), between the firstand seacond seals (35, 37), dividing the transfer chamber axially into first and second compartments.

8. A sea|ing arrangement for a vehicle for providing an airtransfer chamber between a shaft (7) and a hub (9) surrounding theshaft, wherein one is connected to the body of the vehicle and theother to a wheel of the vehicle, the transfer chamber being ring-shaped and confined between the shaft, the hub, and at least a first(35) and a second (37) ring-shaped seal which are axiallyseparated in the axial direction of the shaft, characterised by a thirdsea|ing ring (29) that divides the transfer chamber axially into a first and a second compartment.

9. A sea|ing arrangement according to claim 8, wherein thearrangement comprises a base ring (25), which is attached to the shaft, the third seal (23) being placed in a circumferential groove 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icati0nteXt_MAH.doc 12 (67) in the base ring.

10. A sealing arrangement according to claim 9, wherein thegroove (67) is wider than the width of the third seal (23), such thatan air passage is created to the inner side of the third seal.

11. A sealing arrangement according to any of claims 8-10,wherein a slit (24) is provided in the third ring shaped seal (23)facilitating the radia| expansion of the seal.

12. A sealing arrangement for a vehicle for providing an airtransfer chamber between a shaft (7) and a hub (9) surrounding theshaft, wherein one is connected to the body of the vehicle and theother to a wheel of the vehicle, the transfer chamber being ring-shapedand confined between the shaft, the hub, and at least a first (35) and asecond (37) ring-shaped seal, which are attached to the shaft, axiallyseparated in the axial direction of the shaft, the first and second sealsbeing in moveable contact with an outer ring shaped sleeve (21) whichis arranged to be attached to the hub, characterised by the outersleeve comprising holes (63, 73) providing an outlet for the transferchamber, wherein the holes are elongated in the circumferentialdirection of the sleeve. 12/21/2012 2:03 PM V:\TRELLEBORG FORSHEDA AB\TRELLEBORG FORSHEDAAB\PATENT\CT|\SE\21060983\20121130_21060983_App|icationteXt_MAH.doc