ERICSON CHRISTER (SE)
ERICSON CHRISTER (SE)
| DE2751430A1 | 1979-05-23 | |||
| DE2907581A1 | 1979-09-06 | |||
| US2465560A | 1949-03-29 | |||
| US3014460A | 1961-12-26 |
| 1. | A fluid drive means for a linear reciprocating motion and provided with at least one flexible and collapsible member (15) arranged between elements (11, 12, 14) which move in relation to each other during operation, said member (15) between said elements (11, 12, 14) surrounding a central rod (13) which extends through one of the elements (11, 12), characterized in that said rod (13) together with said member (15) completely delimits a fluid chamber for the pressure fluid which is required for the operation of the drive means and in that said member (15), which is made for instance of an elastomer, consists of a roll membrane and establishes a sealing (19) around the rod (13), for instance a lip sealing. |
| 2. | A fluid drive means according to claim 1, characterized in that the roll membrane (15) is made thicker at one end, so that an indication of bending for the collapse of the membrane comes up where the thicker part (22) changes over to normal wallthick ness. |
| 3. | A fluid drive means according to claim 2, characterized in that said thicker part (22) extends through a little more than a third of the axial length of the membrane (15) so that the membrane (15) will form three layers when it is collapsed. |
| 4. | A fluid drive means according to any of claims 1 3, characterized in that such a member (15) is provided on each side of a plate (14) secured to said rod (13), which plate (14) together with end walls (11, 12) of a cylinder (10) for each member form a pair of said elements, fluid connections (10) being provided in the end walls (11, 12). |
Fluid Drive Means For A Linear Reciprocating Motion
The present invention concerns a hydraulic or pneumatic fluid drive means for a linear reciprocating motion. It is provided with at least one flexible and collapsible member arranged between elements which move in relation to each other during operation. The chief field of application for such a drive means is as a servo-motor.
A drive means of the above mentioned kind is known for instance through the Swedish layout print No. 7305870-3. There the collapsible member is a bellows which is provided only on the side of the shaft or rod opposite the element or piston in question. Generally such a single-acting drive means is unsuitable as a servo-motor, and the bellows is complicated and expansive to manufacture. Further it is impossible to make it double-acting with a pressure-member on the other side of the piston. The US Patent No. 2 465 560 suggests a solution of the sealing problems in a double- acting piston-cylinder-assembly by means of rubber containers or bags in the cylinder chambers.
The object of the invention is to produce in a simple way a linear reciprocating motion from pneumatic or hydraulic forces without high demands for machinery accuracy and without the sealing problems that arise when air or another fluid is enclosed in metal cylinders with sealed components. With other words, a cheaper and simpler alternative to conventional piston-cylinder- assemblies for carrying out control movements is intended. According to the invention this problem is solved in that the rod in the fluid drive means together with said member completely delimit a fluid chamber for the pressure fluid which is required for the operation of the drive means and in that said member, which is
made for instance of an elastomer, consists of a roll- membrane and establishes a sealing against the rod, for instance a lip sealing.
The invention will now be closer described with reference to the accompaniήgdrawing which in an axial section shows an embodiment of the fluid drive means according to the invention.
In the shown embodiment the fluid drive means comprises a housing or cylinder 10 with end walls 11 , 12. In the end walls an output rod 13 is moiin ed for linear movement. The rod 13 carries a pressure plate 14 between the end walls 11, 12. On each side of the pressure plate 14 a pressure chamber is delimited by a membrane 15 r preferably of rubber, and by the rod 13. In each end wall a connection 16 for pressure fluid is provided.
At the pressure plate 14 the membrane 15 is statically sealed against the rod 13. A ring may for instance press a flange 19 of the membrane against the rod 13. At the end walls the membrane 15 is dynamically sealed against the rod 13 by means of a conventional sealing 20, for instance a lip sealing, made in one piece with the membrane 15. Of manufacturing and assembling reasons the side 21 of the membrane bearing on the end walls 11 and 12 respectively is manufactured separately and connected to the main part of the membrane.
When pressure fluid is removed from the pressure chamber on one side and led to the pressure chamber on the other side so that the pressure plate 14. and with ' that the rod 13 moves in one direction the membrane 15 is collapsed in such a way that it rolls up like a roll membrane with one layer outside the other. In order to control this movement a part 22 of the membrane nearest the pressure plate 14 has been made thicker. In that way an indication of bending comes up where this part 22
ends. If for instance this part 22 is made a little longer than a third of the axial length of the membrane the latter will form three layers when it is collapsed.
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