GB2178705A - Tyre inflate/deflate system - Google Patents

Abstract

A tyre deflate/inflate system comprises a manifold (92) mounted on a spindle (14) of a wheel assembly (10). A plurality of spindle passages (98) are supplied with gas under pressure from the manifold (92). The spindle passages (98) are evenly distributed about spindle (14) and open internally to feed driveshaft passages (114) which inflate the tyre via passages in a piston cap (120), hub (26), drum (28), and the wheel. A similar spindle passage (131) is supplied with gas to operate pistons to deflate the tyre (36). The pistons may alternatively be operable hydraulically or electromagnetically. High pressure gas cylinders provide inflate/deflate pressure which, together with the plurality of passages, allow for rapid inflation and deflation of the tyres. <IMAGE>

Description

SPECIFICATION Tyre inflate/deflate system The present invention relates to a tyre inflate/deflate system for a motor vehicle, particularly for a vehicle of a type likely to encounter a variety of terrains on which different tyre pressures are desirable from the point of view of ride comfort and surface traction.

Inflate/deflate systems are known per se where air is supplied from a central source on the vehicle along the wheel axle across a rotary seal to a hub and thence to the wheel.

Nevertheless, known systems have suffered in the past from the length of time it takes to inflate and deflate the tyres.

It is, therefore, an object of the present invention to provide an inflate/deflate system which does not suffer from this disadvantage.

In accordance with this invention a tyre inflate/deflate system for a wheel carried on a hub connected to a drive shaft rotatably disposed in a wheel spindle, comprises a supply of gas under pressure to a non-rotary manifold, a gas connection from the manifold to a plurality of ports disposed about the spindle, spindle passages through the spindle connecting said ports with outlets around an internal circumference of the spindle, a plurality of inlets formed around the driveshaft in the plane of said circumference, rotatable sealing means defining an annular chamber in said plane between the spindle and driveshaft, and a plurality of driveshaft passages connecting said inlets with openings arranged in the end of the driveshaft about its axis and connecting with hub passages in the hub, the hub passages opening into the wheel to inflate/deflate the tyre thereof.

Thus the provision of a plurality of ports, spindle passages and outlets and a plurality of inlets, driveshaft passages, openings and hub passages ensures that despite the physical restrictions imposed on each of these elements by the nature of the components in which they are formed, nevertheless the minimum cross-section through which the gas supply must pass to inflate the tyre can be kept to a maximum resulting in a fast inflate time.

Preferably, the tyre is arranged to be deflated by at least one selectively operable valve in the hub connecting each of said hub passages with atmosphere. In this way, the deflate time of the tyre can also be reduced, it being a function of the number of hub passages connectible to atmosphere.

Preferably said valve or valves are pneumatically oeprated and one spindle passage is a spindle deflate passage and opens in the spindle in a different plane to that of said circumference, one driveshaft passage is preferably also a deflate passage whose inlet opens on the driveshaft in said different plane, rotatable deflate sealing means defining a further annular chamber between the spindle and the driveshaft, but in said different plane, said driveshaft deflate pasage opening at the end of the ddveshaft and connecting with a hub deflate passage to operate the or each valve.

Alternatively said valve may be hydraulically or electromagnetically operated.

Preferably a valve is provided for each hub passage.

The invention is further described hereinafter with reference to the accompanying drawings in which: Fig. 1 is a section through a wheel forming part of a system in accordance with the invention; Fig. 2 is a schematic diagram showing the plan of a vehicle incorporating a system according to the invention; and Fig. 3 is an enlarged portion of Fig. 1.

In Fig. 1 a wheel assembly 10 comprises a swivel housing 12 suspended in a body (not shown) of a vehicle in which the wheel is mounted. A wheel spindle 14 is pivoted about king pins 16 defining a swivel axis 18. The swivel housing 12 has rotatably disposed therein a half shaft 20 which engages a constant velocity joint 22 driving a driveshaft 24.

The driveshaft is rotatably disposed within the spindle 14. Thus even though the wheel 10 can pivot about the axis 18, nevertheless drive from the half shaft 20 can be transmitted to the driveshaft through the constant velocity joint 22. If the wheel is not requried to be steered, then the swivel housing 12 can be rigidly connected to the spindle 14 and the half shaft 20 can be integral with the driveshaft 24.

In either event the driveshaft 24 has, adjacent its end, a hub 26 non-rotatably disposed thereon. The hub 26 is connected to a drum 28 which is in turn connected to a wheel 30.

The wheel 30 is supported via bearings 32 directly onto the spindle 14. Thus the stub axle 24 does not require to support the weight of the vehicle and merely transmits torque. A bush 34 between thestub axle 24 and the spindle 14 is therefore the only bearing required between them. A tyre 36 is mounted on the wheel 30. The tyre is retained on the wheel 30 by its beads 40 which are held in position by rims 42 and 44 of the wheel and a bead lock 38. The rim 42 is removable to allow the tyre to be changed.

The bead lock 38 also incorporates a run flat rim 46 to allow the wheel to run while the tyre is completely deflated without damage to the tyre.

The tyre is of course pneumatic and is supplied with air under pressure through a system schematically illustrated in Fig. 2. Here, two gas cylinders 56 are filled with air to a pressure of approximately 4,000 psi. The tanks 56 are mounted on a chassis 58 of the vehicle. A switch 60 is operable in a cab 62 of the vehicle to select in an output 64 thereof, from which of the two cylinders 56 the gas supply is to be taken. The pressure in the output 64 is monitored by a pressure gauge 66 mounted in the cab 62. The output 64 provides an input to a further switch 68 having two outputs 70 and 72. Again, the switch 68 is operable from the cab 62. When this is positioned to direct gas pressure from input 64 into either of the outputs 70,72, then the other output is isolated.When it is desired to inflate the tyres 36a,36b of the vehicle, the switch 68 is switched to apply gas pressure in the output 72 thereof. The output 72 divides into two branches 74,76 feeding pressure regulators 78, 80 respectively. The outputs of the pressure regulators 78,80 can be monitored in the cab 62 by pressure gauges 82,84 respectively. The regulator 78 feeds the front wheels 36b of the vehicle while the regulator 80 feeds the rear wheels 36a of the vehicle.

Turning to Fig. 1, at each wheel a manifold 90 is mounted on the wheel spindle 14. The manifold 90 has an inlet 92 of relatively large bore to which is connected a branch of the regulated gas supply in lines 74 or 76. The inlet 92 of the manifold 90 connects with a plurality of outputs 94 of relatively narrow bore. Each bore 94 is connected by a pipe (not shown) to an inlet 96 on the wheel spindle 14. The number of inlets 96 on the spindle 14 is the same as the number of outlets 94 on the manifold 90. The inlets 96 are preferably evenly distributed about the spindle 14, that is about its axis 100.

The inlets 96 open into spindle passages 98 lying parallel to the axis 100 around the spindle 14. The spindle passages 98 open to the interior of the spindle 14 through outlets 102 around an internal circumference of the spindle 14, which circumference lies in a plane 104.

The driveshaft 24 is provided with inlets 106 about a circumference thereof lying in the same plane 104 in which the outlets 102 are disposed. Seals 108 and 110 define an annular chamber 112 between the driveshaft 24 and spindle 14. Thus although it is preferred that the number of outlets 102 corresponds with the number of inlets 106, this is not absolutely necessary.

The inlets 106 open to driveshaft passages 114 through the driveshaft 24 and lying parallel to the axis 100. The driveshaft passages 114 terminate in sockets 116 in an end face 118 of the driveshaft 24. A piston cap 120 has teats 122 which engage in the sockets 116. Each teat 122 has an O-ring seal 123 to seal it in the socket 116. Moreover, each teat 116 has a passage 124 communicating with the end of the teat. The passage 124 communicates with a hub passage 126 defined in the hub 26 and to which the piston cap 120 is rigidly connected, an O-ring 128 seals the connection between the piston cap 120 and the hub 26.

The drum 28 is provided with passages 130 which communicate with the hub passages 126 via seals 132. The drum passages 130 communicate in turn with passages 134 in the wheel 30, O-ring 136 providing a seal therebetween. Returning to Fig. 1, the wheel passage 134 opens into an annular space 138 defined by the bead lock 38. Finally, passages 140 communicate the space 138 with the interior of the tyre 36.

Thus in summary, when the switch 68 is switched to an "inflate" position, pressure from one of the two cylinders 56 is fed to the line 72 and thence to the pressure regulators 78,80. Air under an appropriate pressure for the front or rear wheels is thus fed into lines 74,76 respectively and thence to the manifold 90 on each wheel assembly 10.

From there the air is fed via pipework (not shown) to each of the inlets 96 on the spindle 14, the spindle passages 98, the spindle outlets 102, the annular chamber 112, the driveshaft inlets 106, the driveshaft passages 114, the sockets 116 and teats 122, the piston cap passages 124, the hub passages 126, the drum passages 130, the wheel passages 134, the annular space 138 and finally the bead passages 140 to the interior of the tyre 36.

When it is desired to deflate the tyres 36, however, the switch 68 is switched into a position where the gas pressure is fed to lines 70. The line 72 is simultaneously isolated.

The line 70 is fed to each manifold 90 on each wheel assembly 10 and thence to a spindle deflate passage 131 formed in the spindle 14 lying parallel to the axis 100 and between the spindle passages 98.

The spindle deflate passage 131 opens to the interior of the spindle through an outlet 133 lying in a plane 139 axially spaced from the plane 104. The driveshaft 24 contains an opening 135 disposed in said plane 139 and connecting with a driveshaft deflate passage 137 lying concentrically with respect to the axis 100. The driveshaft deflate passage 137 terminates in a socket 141 centrally in the end of the driveshaft 24 and connecting with a teat 142 formed centrally on the piston cap 120. An O-ring 144 seals the teat to the socket.

A cap deflate passage 146 opening at the teat 142 communicates with a plurality of radially disposed cap deflate passages 148 connecting the passage 146 with each of a number of cylinders 150 formed in the piston cap 120. The number of cylinders 150 corresponds with the number of driveshaft passages 114, cap passages 124, hub passages 126 and drum passages 130.

In each cylinder 150 there is disposed a piston 152 defining a pressure chamber 154 to which each cap deflate passage 148 is connected, Each hub passage 126 has a branch 156 which returns to the piston cap 120 via O-ring seals 158. The passage 156 is connected with an annular chamber 160 formed around the piston 152 and in which is disposed a spring 162 urging the piston 152 to a position in which its end 164 seals against a shoulder 166 formed in the piston cap 120.

An O-ring 168 provides the seal between the shoulder 166 and end 164. The other end 170 of the piston 152 is sealed in the cylinder 150 by an O-ring 172.

Thus when pressure is fed to the pressure chambers 154, the piston 152 is lifted off its seat on the shoulder 166, venting the annular chamber 160 and thus enabling the tyre 36 to deflate via the passage 140,annular space 138, passages 134,130,126 and 156 and an nular chamber 160. A rubber boot 180 surrounds the piston cap 120 protecting the pistons 152 from dirt and dust, which boot 180 is lifted off its seat 182 when the tyre 36 is deflated.

Although pneumatic means is described herein for operating thatthe pistons 152, it is quite feasible that hydraulic means could be employed in which the deflate passages would be much as shown. The switch 68 would be compound in which the line 72 is either pressurised with or isolated from the cylinders 56 and simultaneously the line 70 is released from hydraulic pressure or pressurised therewith respectively. Alternatively, the pistons could be operated by a solenoid in which event the deflate passages can be dispensed with entirely and the switch 68 is arranged as a joint pneumatic electric switch.

From the foregoing it is evident that the s eed with which the tyre 36 can be inflated is dependant on the number and bore diameters of the spindle passages 98, driveshaft passages 114, cap passages 124, hub 126 and drum passages 130. Similarly, the speed with which the tyre can be deflated depends on the number of passages 134,130,126 and 156 and the number of pistons 152 and cylinders 150. The present embodiment illustrates a piston 152 and cylinder 150 for each hub passage 126, but this is not essential.

Although it is preferred that the number of spindle passages 98 corresponds with the number of driveshaft passages 114 and consequent passages 124,126,130 etc., nevertheless it is evident that the relative numbers of the passages on either side of the annular chamber 112 is independent of one another. It will be found that six evenlyspaced spindle passages 98 and driveshaft passages 114 is sufficient to ensure a rapid inflate/deflate time.

The speed of inflation and deflation is further enhanced by the high pressure gas cylinder sources 56 which can either be of the quick release type for return to depot and recharging or of a permanent type with a suitable compressor built on board to maintain the high pressure therein.

The present invention provides, of course, that inflation and deflation of the tyres can be effected from the cab by the appropriate remote manipulation of the switch 68.

Although the embodiment illustrated shows a brake reaction disc 200 arranged on the spindle 14 outboard of the wheel bearing 32, it is quite feasible to arrange the disc 200 as a more usual backplate inboard of the wheel bearing 32 without adversely affecting the performance of the invention.

Claims (23)

1. A tyre inflate/deflate system for a wheel carried on a hub connected to a driveshaft rotatably disposed in a wheel spindle, the system comprising a supply of gas under pressure to a non-rotary manifold, a gas connection from the manifold to a plurality of ports disposed about the spindle, spindle passages through the spindle connecting said ports with outlets around an internal circumference of the spindle, a plurality of inlets formed around the driveshaft in the plane of said circumference, rotatable sealing means defining an annular chamber in said plane between the spindle and driveshaft, and a plurality of driveshaft passages connecting said inlets with openings arranged in the end of the driveshaft about its axis and connecting with hub passages in the hub, the hub passages opening into the wheel to inflate/deflate the tyre thereon.

2. A system as claimed in claim 1 in which the hub passages are partially formed in a piston cap on the end of the driveshaft, the cap having teats engaging sockets in said openings and connecting them with said hub passages.

3. A system as claimed in claim 2, in which said teats are cylindrical and have O-ring seals to seal against the sockets of said openings which are also cylindrical.

4. A system as claimed in any preceding claim, in which said ports, spindle passages and outlets are evenly distributed about the axis of the wheel.

5. A system as claimed in any preceding claim, in which the inlets, driveshaft passages, openings and hub passages are evenly distributed about the axis of the wheel.

6. A system as claimed in any preceding claim, in which the number of ports, spindle passages and outlets is the same as the number of inlets, driveshaft passages, openings and hub passages.

7. A system as claimed in any preceding claim, in which there are from two to ten ports, spindle passages, outlets, inlets, driveshaft passages, openings and hub passages.

8. A system as claimed in claim 7, in which there are six ports, spindle passages, outlets, inlets, driveshaft passages, openings and hub passages.

9. A system as claimed in any preceding claim, in which the tyre is deflated by at least one selectively operable valve in the hub connecting each of said hub passages with atmosphere.

10. A system as claimed in claim 9, in which said valve is operable by pneumatic pressure and in which one spindle passage is a spindle deflate passage and opens in the spindle in a different plane to that of said circumference, and one driveshaft passage is a driveshaft deflate passage whose inlet opens on the driveshaft in said different plane, rotatable deflate sealing means defining a further annular chamber between the spindle and driveshaft, but in said different plane, and said driveshaft deflate passage opening at the end of the driveshaft and connecting with a hub deflate passage to operate the or each valve.

11. A system as claimed in claims 9 or 10 in which said valve comprises a valve member biassed towards a valve seat and a piston operating said valve member and disposed in a cylinder connected to said hub deflate passage.

12. A system as claimed in claims 10 or 11, in which said driveshaft deflate passage is coaxial with the driveshaft.

13. A system as claimed in any of claims 10 to 12, including switching means selectively operable to switch said supply of gas under pressure to one of said spindle passages and said spindle deflate passage, the other thereof being isolated.

14. A system as claimed in claim 9 in which said valve is operated by hydraulic pressure.

15. A system as claimed in claim 9 in which said valve is electro-magnetically operated.

16. A system as claimed in any of claims 9 to 15, in which a valve is provided for each hub passage.

17. A system as claimed in any preceding claim in which said supply of gas under pressure is a high pressure gas cylinder.

18. A system as claimed in claim 17 including a compressor to pressurise said gas cylidner.

19. A system as claimed in claimsl7 or 18, including a regulator to regulate the pressure of said gas supply.

20. A system as claimed in claim 13 and claim 19 in which said switching means is arranged in the system in advance of said regulator, unregulated gas pressure providing said pneumatic deflation pressure.

21. A system as claimed in claims 19 or 20, in which two regulators are provided, one for the front wheels and one for the rear wheels of the vehicle in which the system is fitted.

22. A system as claimed in any preceding claim, in which said manifold is disposed on the spindle and is provided with gas under pressure from a flexible pipe of relatively large bore from the body of a vehicle in which the system is fitted and distributes the gas to said ports by a plurality of pipes of relatively small bore, but which in total offer no greater resistance to airflow than said one large bore pipe.

23. A tyre inflate/deflate system substantially as hereinbefore described with reference to the accompanying drawings.