Land vehicles – Body elevation or tilt – Terrain slope compensation
Patent
1998-02-12
1999-10-26
Swann, J. J.
Land vehicles
Body elevation or tilt
Terrain slope compensation
280124166, 1510405, 1041382, B60S 900
Patent
active
059714042
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to self-centering suspensions for in-pipe use.
BACKGROUND OF THE INVENTION
In-pipe vehicles which require centering within the pipe are normally supported by polymer cups, wire brushes, or several wheels on independently spring loaded lever arms. The former two generate high levels of frictional resistance, and the latter requires relatively stiff springs on the lever arms partially to counteract the load exerted by the opposite lever arms. Therefore centralising a vehicle in a pipe to within accurate limits, while maintaining some automatic adjustment for variations in pipe size, is difficult to achieve and requires large forces, thus high frictional resistance to linear motion of the vehicle, and high resistance to traversing a pipe of reducing diameter.
SUMMARY OF THE INVENTION
According to the invention there is provided a self-centering suspension for use in supporting a vehicle or vehicle intended to travel in a pipeline, said suspension comprising a body and a set of wheels, each wheel being mounted at a first end of an arm having a second end connected to said body by a rotary joint permitting the wheel to move inwards and outwards to accommodate changes in the diameter of an inner surface of the pipeline as the wheels traverse the inner surface, spring means arranged to be stressed by inward movement of said wheel, each arm having a stub arm eccentrically arranged with respect to said rotary joint, each stub arm slidingly engaging a circumferential groove in a ring reciprocable on the body longitudinally thereof, and the stub arms and ring together forming coupling means arranged to allow only movement of all the wheels in the set simultaneously.
Preferably, said spring means comprises respective rotary spring means arranged between said arm in each case and the body, and the spring means being arranged around the respectice rotary joint.
DETAILED DESCRIPTION OF THE DRAWINGS
The invention will now be further described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic three-dimensional view of the suspension;
FIG. 2 is an end elevation of the suspension shown in FIG. 1; and
FIG. 3 is a vertical cross-section on the line III--III in FIG. 2, with parts removed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 to 3 show a self-centering suspension 10 for use in supporting a vehicle intended to travel in a pipeline 12. For example, the pipeline 12 is a cast iron gas main and contains a liner 14 of polyethylene upon the inner surface of which wheels 16, 18 run. There are three wheels 16 in a first set of wheels spaced apart equiangularly around a body 20. There are three wheels 18 in a second set of wheels also spaced apart equiangularly around the body 20. The wheels 18 each lie in a common plane with a wheel 16 in this example. However, this is not essential and the wheels 16, 18 may lie in different planes. The two sets of wheels 16, 18 are spaced apart along the length of the body 20.
The vehicle is intended to be used, in this example, for the purpose of cutting an aperture in the liner at an offtake so that a plastic service pipe can be inserted in an existing steel service pipe and the plastic pipe joined to the liner at the aperture cut by the machine. However, the invention is operable in pipelines and ducts whether they are lined or not.
The body 20 carries three brackets 21 arranged equiangularly about the body 20. Each bracket 21 terminates at opposite ends in arms 22.
The following description applies to the first set of wheels 16.
Each wheel 16 is mounted on a pin 24 between two arms 26 of a fork formed at one end of a lever arm 28. The other end of the lever arm 28 is connected by a rotary joint in the form of a pin 30 to adjacent arms 22 of the brackets 21.
Torsion springs 40, 42 are arranged around the pin 30 between the lever arm 28 and the arms 22 fixed to the body 20. Inward movement of the wheel 16 and the lever arm 28 stresses the torsion springs 40, 42.
The lever arm
REFERENCES:
patent: 2579813 (1951-12-01), Frank
patent: 2742259 (1956-04-01), Boucher
patent: 4006359 (1977-02-01), Sullins et al.
patent: 4218923 (1980-08-01), Triplett et al.
patent: 4537136 (1985-08-01), Douglas
patent: 5018451 (1991-05-01), Hapstack
patent: 5428862 (1995-07-01), Sailer
BG plc
Dunn David R.
Swann J. J.
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