Expansible chamber devices – Relatively movable working members – Moving cylinders
Patent
1994-05-20
1996-01-02
Denion, Thomas E.
Expansible chamber devices
Relatively movable working members
Moving cylinders
92117R, 92140, 92187, F01B 1500
Patent
active
054798469
DESCRIPTION:
BRIEF SUMMARY
The invention concerns machines with pairings of pistons and cylinders intended to embody a exchange of energy between an under pressure fluid and a mechanical member and more particularly to embody an air or any other gas compressor without nevertheless excluding the embodiment of a motor activated by the energy of a generally gaseous fluid.
Machines with pistons connected to mechanical energy members most frequently use the conventional connecting rod/crank system or sometimes a plate which oscillates around an oblique crank rotating around an axis parallel to the piston/cylinder pairing. There also exist slide or cam systems. All these systems introduce transverse forces, that is radial on the pistons relatively to their axis, which constitutes a friction factor with wear and creates dust. A rectilinear guiding cancels the transverse forces between the piston and the cylinder, but it requires lubrication which is a source of pollution and renders the unit heavy with a large spatial requirement.
The method is known on how to cancel the obliquity of a connecting rod relatively to the piston and the corresponding forces by using an oscillating cylinder. However, this creates transverse inertia forces due to its oscillation which are the source of the same drawbacks as mentioned above.
The aim of the invention is to avoid any systematic friction between the cylinder and the piston so as to render minimal the wear of these elements and enable them to function for a long period of time, especially for non-lubricated machines without any gasket between the piston and the cylinder and thus avoid creating pollution by oil or particles introduced by the wear of these elements.
For example, this embodiment for gas compression, even at extremely high pressures, is possible by accurately adjusting the surfaces opposite the cylinder and piston and for a significant length of the opposite parts of these two elements.
For example, with a radial play of 1 .mu.m and a piston working length of 40 mm, it is possible to reduce the leak of a gas along this play to a value of less than 10% of the pumped flow.
So as to embody a piston machine providing these advantages, it is necessary to obtain a movement of the piston in the cylinder which is rectilinear within the limits of this extremely slight play without any systematic radial force. Thus, the piston shall be connected to a mechanical member which comprises a mobile element driven from the same alternative rectilinear movement and linked to the piston or even to the cylinder if the latter is mobile. In fact, any oblique linking, such as a connecting rod linked to a crank, creates under the force of the piston a radial component reaction on the latter.
There are various mechanical systems where an element is driven by an alternative rectilinear or almost rectilinear movement.
One of the earliest systems is WATT rodding, an example of this being shown on FIGS. 3 and 4 to be described subsequently.
Another known system is a gearing known as LA HIRE and constituted by a fixed ring internally toothed with a halfsized satellite gear and for which a point on the original diameter describes a straight line which passes through the centre of the ring.
So as to drive an elongated piston and with an extremely slight play relatively to a cylinder, it is possible to connect either of these two elements to a part driven by a movement which is rectilinear within the limits of this play.
If, however, the link is rigid, it is necessary to either align the mechanical member with a positioning tolerance better than the piston/cylinder play, which in practice cannot be achieved when this play is several .mu.m, all the more so when the expansions and deformations on functioning aggravate the problem, or to allow the mechanical member to have transverse positioning freedom but its weight is then added to that of the driven element, thus resulting is producing radial forces due to heaviness or vibrations, which creates rubbings between the piston and the cylinder.
So as to resolve this problem
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patent: 2146133 (1939-02-01), Tweedale
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patent: 3314336 (1967-04-01), Jorgji
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patent: 4231672 (1980-11-01), Blanpain et al.
patent: 4443163 (1984-04-01), Gaither
patent: 4511276 (1985-04-01), Doutt
Denion Thomas E.
Drucker William A.
Seref
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