Implements or apparatus for applying pushing or pulling force – Metallic spring stretcher and/or compressor
Patent
1998-12-02
1999-09-21
Eley, Timothy V.
Implements or apparatus for applying pushing or pulling force
Metallic spring stretcher and/or compressor
29215, 29225, 29226, 29227, B60P 148
Patent
active
059543159
DESCRIPTION:
BRIEF SUMMARY
In the field of mounting and dismounting motor vehicle shock absorber springs, drive mechanisms constituted by actuators are used which move apart or towards each other two jaws or cups that are placed facing each other and between which the turns of the spring are engaged.
BACKGROUND OF THE INVENTION
In most cases, the actuator used is a screw actuator and the body can be in two telescopic portions. The larger-diameter portion carries a screw that is prevented from moving in translation relative to the said portion while the smaller-diameter portion carries a nut, said portion being prevented from rotating relative to the larger-diameter portion. By driving the screw via the end of the actuator body, it is thus possible to extend or to retract the body, and thus to move the cups which are fixed thereto either away from or towards each other.
There also exist fluidized pressure actuators that can be single-acting or double-acting, for providing the above relative displacement. Particular mention can be made of the actuator described in document U.S. Pat. No. 4,034,960. In that document, the spring-compressor has two actuators side by side, each having a fixed piston and a moving cylinder, one cup being secured to the moving cylinder of each the actuators, while another cup is carried by a plate which is fixed relative to the piston and which is secured to a guide tube for guiding each of the moving cylinders relative to the piston. The presence of the two actuators side by side is necessary firstly to enable sufficient compression force to be developed, given that the device is a pneumatic device, and secondly to provide rectilinear guidance for the moving cup relative to the fixed cup so as to oppose the tendency of the spring to tilt one cup relative to the other. Finally, the forces involved are such that to oppose buckling, the cylinder of each pneumatic actuator must remain well within the corresponding guide tube when the device is at its maximum extension. This means that the axial size of the apparatus is large for given stroke. All of those reasons that give rise to large bulk mean that that apparatus is ill-adapted, particularly to taking action beneath a motor vehicle body when changing or repairing a shock absorber.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention relates to a pressurized fluid actuator, in particular a hydraulic fluid actuator, that makes it possible with an operating pressure of the order of a few hundred bars, to provide an apparatus that is small in diameter (about 60 mm). In addition, the device is designed to present minimum longitudinal size for given compression stroke.
To this end, the invention thus provides a hydraulic spring-compressor comprising a body formed by a first tubular part closed at one of its ends by an end wall in which there is received the end of a hollow rod extending axially inside the first tubular part and whose other end is shaped to form a piston, and by a second tubular part having an end closed by an end wall through which the hollow rod passes, which second tubular part is mounted to slide in sealed manner on the rod and the piston, defining therebetween a chamber of variable volume that is continuously in communication with the inside volume of the hollow rod, the first tubular part having on its outside surface, at its end remote from the end wall, attachment means for attaching to a compression cup, the second tubular part having on its outside surface, at its end remote from its end wall, attachment means for attachment to a compression cup. In order to obtain minimum size for the device, the hollow rod is longer than the first tubular part so that its piston-shaped end is situated beyond the attachment means carried by the first tubular part, the closed end of the second tubular part is situated outside the attachment means of the first tubular part when the variable volume chamber is at its minimum volume, a link sleeve is slidably mounted between the first and second tubular parts respectively on the inside and outside
REFERENCES:
patent: 2893719 (1959-07-01), Gattiker, Jr. et al.
patent: 4034960 (1977-07-01), Kloster
patent: 4105188 (1978-08-01), Mendoza et al.
patent: 5564172 (1996-10-01), Klann
Eley Timothy V.
Halpern Benjamin M.
Mecanique Energertique
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