Expansible chamber devices – With assembly or disassembly facilitating means
Patent
1998-05-29
2000-03-07
Denion, Thomas E.
Expansible chamber devices
With assembly or disassembly facilitating means
92172, 92256, 403372, 403375, 403376, F01B 2900
Patent
active
060325690
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a device for locking a piston onto a piston rod, for example for a hydraulic or pneumatic cylinder. The invention also concerns a locking clip and a piston intended to be locked onto a piston rod by the locking clip.
There are a number of known solutions to how a piston can be locked onto a piston rod for a hydraulic or pneumatic cylinder.
DESCRIPTION OF THE RELATED ART
A known example is when the piston is threaded onto the end of the piston rod after which a hole is bored radially through the piston and the piston rod. Subsequently, a locking means in the shape of a cylindrical pin is pressed into the hole, whereby relative rotation between the piston and the piston rod is prevented.
In another known example a two-piece piston is used where both parts of the piston are threaded onto a piston rod. The outer part is provided with a number of axially directed screws which are screwed against the other part so that an axially directed force occurs in the threaded joint between the piston rod and the piston parts. In this way a firm locking of the piston parts onto the piston rod is achieved.
When changing the packing in a cylinder end through which the piston rod passes, the piston, because of the design of the piston rod, must be dismantled from the piston rod. In big cylinders this dismantling must sometimes be performed in uncomfortable circumstances, e.g. in the field, wherefore a complicated locking device which consists of a number of small parts is unsatisfactory.
Large forces and load changes act between the piston and the piston rod. Because of the elasticity of the material of the piston and the piston rod, the large forces can produce a relative movement between the piston and the piston rod in the axial direction. If the locking means of the locking device then takes up the whole of the force which acts between the piston and the piston rod, the locking device will be destroyed because of fatigue.
SUMMARY OF THE INVENTION
An object of the present invention is to produce a cheaper, better and more secure device for locking against rotation a piston onto a piston rod, which device consists of only a small number of components.
A further object is to achieve a device for locking a piston onto a piston rod, which device permits assembly and disassembly with simple tools and manipulations.
Yet another object is to achieve a device for locking a piston onto a piston rod which device is designed to cope with large forces and load changes.
These objects are achieved through the piston being equipped with at least one radial through-hole which is intended to be positioned over a groove in the piston rod and by a locking clip, which comprises a first straight end part and a curved part, being intended to have its first end part extend through the radial hole in the piston and into the groove in the piston rod, in addition to which the piston is provided with a peripheral groove in which a part of the curved part of the locking clip is intended to rest in a piston-locking position.
Owing to the curved part of the locking clip describes an arc which is less than 180.degree.a simple mounting of the locking clip on the piston and the piston rod is made possible.
The piston comprises a circular body with an axial through-hole for the introduction of a piston rod and a circumferential groove which is in the same radial plane on the piston as the radial hole.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described below in more detail by means of an embodiment with reference to the appended drawings, in which:
FIG. 1 shows an end view of a piston which is mounted on a piston rod and fastened by means of a first embodiment of a locking clip according to the invention;
FIG. 2 shows a lateral view of the device in FIG. 1; and
FIG. 3 shows a lateral view of a second embodiment of the locking clip according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1 and 2 show a piston 1 which is equipped with a threaded, axial through-ho
REFERENCES:
patent: 3625554 (1971-12-01), Mottais et al.
patent: 3648348 (1972-03-01), Freimuth
patent: 4192225 (1980-03-01), Moyer
patent: 4630958 (1986-12-01), McCallister
patent: 4771678 (1988-09-01), Walker
patent: 5245911 (1993-09-01), Yuda
Denion Thomas E.
Volvo Wheel Loaders AB
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