FLUID DRIVE MEANS FOR A RECIPROCATING MOTION

ENTRAINEMENT FLUIDIQUE POUR MECANISME A MOUVEMENT ALTERNATIF

English Abstract

Abstract Of The Disclosure
A fluid drive means for a linear reciprocating
motion is 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. The member (15) surrounds between
said elements (11, 12, 14) a central rod (13), which
extends through one of the elements (11, 12). Together
with the rod the member (15) completely delimits a
fluid chamber for the pressure fluid which is required
for the operation of the drive means. The member (15)
which is made for instance of an elastomer constist of
a roll-membrane and establishes a sealing (19) around
the rod (13).

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluid drive means for a 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),
comprising at least one fluid chamber for the pressure fluid
which is required for the operation of the drive means being
situated between two of the elements and partially delimited
by said member, said member being made for instance of an
elastomer and comprising a roll membrane having a controlled
rolling originating at a specified location, a dynamic sealing
(20) for instance a lip sealing being established around the
rod (13), where it extends through said one of the elements,
the rod being statically sealed by said member of its connection
with another of said elements.
2. A fluid drive means according to claim 1 wherein
said roll membrane (15) has a change in thickness at, said
specific location.
3. A fluid drive means according to claim 2, character-
ized 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).
5. A fluid drive means according to claim 1 wherein
said membrane has a top wall which is thicker than the side
walls of said membrane so that when the pressure fluid is
applied during the operation of the drive means a passage way
is defined between the external surfaces of the side walls and
the internal surface of the fluid chamber to permit the passage
of a fluid such as a lubricating fluid for said membrane.
6. A fluid drive means according to claim 1 wherein said
membrane has a top wall which is movable and is part of the
rolling process.
7. A fluid drive means according to claim 1 wherein
said membrane forms an S-shaped roll.
8. A fluid drive means accroding to claim 1 wherein
the controlled rolling of said membrane originates only at
said specific location.
9. A fluid drive means according to claim 1 wherein
the controlled rolling originates at said specific location
due to the variation in wall thickness of said membrane at
said specific location.
10. A fluid drive means according to claim 1 where said
member partially covers the axial length of said central rod.

Description

6 !340
DESCRIPTION
The present invention concerns a hydraulic or pneumatic fluid
drive means for a reciprocating motion. It is provided with a-t least one
flexible and collapsible n~nber arranged between elements which Eve 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 Cowan for
instance through the Swedish layout print No. 7305870-30 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-actiny drive means is unsuitable as a serv~-motor, and the
ye puns
bellows is co-.nplicatea and~q~3iaiY~ to manu~cture. 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 issued March 29, 1949 to Warnke,
suggests a solution of the sealing problems in a double-acting piston-
cylinder-assembly by means of rubber containers or jags in the cylinder
chambers.
The object of the invention is to produce in a simple way
a reciprocating motion for pneumatic or hydraulic forces without high
ZOO 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 mDwements
; is intended.
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According to the invention this problem is solved in that the
God in the fluid drive means together with said member completely delimit
a fluid chamfer for the pressure fluid which is required for the operation
of the drive means and in that said member, which is
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made or instance ox an elastomers consists of a roll
membrane and establishes a sealing against the rod, owe
instance a lip sealing. I
The invention will now be sat described
with reference to the accompany drawing which in an
axial section show an embodiment ox 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 lo.
12. In the end walls an output rod 13 is mounted 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, preferably ox rubber, and by the rod 13.
In each end wall a connection 16 for pressure fluid is
provided.
t the pressure plate 14 the membrane 15 it
statically sealed against the rod 13. A rink may for
instance press a flange 19 ox the membrane against the
row 13. At the end walls the membrane 15 is dynamically
sealed against the rod 13 by means ox a conventional
sealing 20, for instant e a lip sealing, made in one
piece with the membrane 15. Of manufacturing and
assembling reasons the side 21 of the membrane bearing
~25 on the end walls 11 and 12 respectively is manufactured
separately and connected to the main part ox the
membrane.
When pressure fluid is removed from the pressure
chamber on one side angled to the pressure chamber on
the other Saudis that the pressure plate 14 and wit that
the rod 13 moves in one direction the membrane 15 is
collapsed in such a without 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 us where this part 22
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ends. If for instance this part 22 is made a little
longer than a third of the axial length ox the membrane
eke latter will form three layers when it is collapsed.
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