Tool driving or impacting – Means to drive tool about an axis – Fluid motor
Patent
1998-08-25
2000-11-28
Vo, Peter
Tool driving or impacting
Means to drive tool about an axis
Fluid motor
173 51, 173121, 1731621, 173204, 173211, 173212, B25D 900
Patent
active
061522457
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a compressed-air-operated percussion mechanism including a housing and two bodies movable axially to-and-fro therein, i.e. a first body or percussion body and a second body or balancing body for the purpose of outbalancing the striking movements of the percussion body and thus de-vibrate the entire mechanism, an operating chamber defined between said bodies, an inlet passage emerging in said operating chamber for supplying compressed air, below called high-pressure air, to the chamber for the purpose of separating, against the action from spring means, the bodies from each other while executing an operating stroke, wherein compressed air of reduced pressure, below called low-pressure air, is evacuated from the operating chamber to at least one outlet during a return stroke, said supply of high-pressure air to the operating chamber being regulated by an intermittently opening, primary valve device.
Percussion mechanisms of this type are in practice used for devices of quite different types within quite different areas. As an example ram devices, hand tools for drilling, chiselling, engraving, hammering and surface treatment, devices for vibrating screens, feeding chutes and the like may be mentioned. An especially frequent field of use for the percussion mechanisms is as driving arrangements for chisel or needle scalers.
Since the percussion mechanisms require quick sequences of operation they are fed pneumatically, i.e. by compressed air.
PRIOR ART
A percussion mechanism of the type defined in the preamable is previously known in different versions from SE 9203456-0 and SE 9403729-8. In practice this known percussion mechanism operates with a primary valve device in the shape of a spigot connected with the percussion body, said spigot being movable through a through-going hole in an end wall of the balancing body. The spigot has on one hand a thin shank and on the other hand a thickened end portion having a diameter corresponding wits the diameter of the hole in the end wall. When the percussion and balancing bodies are approached to each other and the operating chamber has a minimal volume, the high-pressure air in an inlet passage in the balancing body is allowed to flow into the operating chamber in order to initiate the operating stroke. When the bodies are distanced from each other to a certain degree the thickened end portion of the spigot is however entered into the hole in the end wall and seals said hole, whereby further supply of compressed air to the operating chamber is made impossible. Thus the operating stroke is terminated and during a return stroke the bodies are again approaching each other. This valve device is thus principally serving as an air flow limiter having primarily the purpose of reducing the consumption of compressed air.
A disadvantage of the device known from SE 9203456-0 and SE 9403729-8 is that the percussion body and its working element, e.g. a scaler or a set of needles, achieve a limited length of stroke. Another disadvantage is that the pressure in the operating chamber decreases towards the end of each operating stroke. This means that the working element during the end phase of the individual operating strokes is acting with a limited force only.
OBJECTS AND FEATURES OF THE INVENTION
The present invention aims at overcome the disadvantages mentioned above and create an improved percussion mechanism. A primary object of the invention is thus to create a percussion mechanism that can be designed with an arbitrary length of stroke at the same time as the consumption of compressed air is kept at a minimum level, i.e. by cutting off the supply of compressed air to the operating chamber during the main part of each return stroke. Another object is to create a percussion mechanism that manages to operate with one and the same high air pressure during the entire operating stroke, i.e. without a pressure reduction at the end of each operating stroke.
According to the invention at least the primary object is atta
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Calve Jim
Vo Peter
LandOfFree
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