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Pressurised fluid maintains piston seal
Patents Patents Pressurised fluid maintains p i s t o n seal
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Title: S e a l i n g s y s t e m P a t e n t number: U S 5 7 0 1 7 9 7 Date: 3 0 t h D e c e m b e r 1 9 9 7 Inventor: Frank M o h n Assignee: F r a m o E n g i n e e r i n g A piston reciprocally moving within a cylinder is often exposed to different fluid p r e s s u r e s on its two opposed sides. This difference in pressure gives a tendency for leakage between the piston and cylinder wall, of fluid from the higher p r e s s u r e side into the lower p r e s s u r e side. Such contaminating leakage can be problematic. This invention describes a improved sealing system for a piston reciprocally moving within a cylinder, and is shown in Figure 1 and Figure 2. The piston head (2), is reciprocally driven within the cylinder (1), by a piston rod (5}, which extends into a motor housing (6). The piston rod is spaced from the cylinder wall to provide a c h a m b e r (7), into which lubricant oil is fed. The improved sealing system is based on supplying higher
Figure I. P a s s a g e s In t h e cylInder h e a d help m a i n t a i n t h e seal.
pressure lubricating oil to a space (18) between the two groups of seal rings (19, 20) at the cylinder head (2). On the piston suction stroke, (to the right as shown in Figure 1), lubricating oil enters a chamber (12), through the passage (14). On the delivery stroke, (to the left as shown in Figure 1), the fluid within this c h a m b e r is pressurised. It is prevented from escaping back down the passage (14), by a n o n - r e t u r n valve (15), and is forced into the gap (18), between the seal rings. This fluid between the seal rings is at a higher pressure than the fluid media on either side, helping to prevent leakage.
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Figure 2. The lubricant oil is forced b e t w e e n t h e seal rings.
Sealing Technology No. 51
WATER
One piece seal stays in place Title: One p i e c e seal w i t h f a s t e n i n g s e c t i o n and s e a l i n g section Patent number: U S 5 7 1 6 0 5 1 Date: 1 0 t h February 1 9 9 8 Inventors: M Cornea, L Lippert Assignee: M a n n e s m R n n R e x r o t h Passages at the interface between two components, s u c h as a screw hole or fluid conduit joining a valve housing to a block, are usually sealed with O-rings or square rings. These seals are positioned within a gap between the components. However, the rings are rarely secured against loss, and awkward handling of the component can cause them to fall out of the recesses. The inclusion of projections on the axial seal, which are pressed into corresponding holes in the metal piece, can help to maintain the position of the seal. This can result in the sealing portion of the axial seal protruding from the piece, allowing dirt particles to collect between the sealing portion and the sheet metal piece which c~m negatively affect the sealing action. This invention is a modified axial seal, made up of three Orings. TWo outer O-rings are joined to the centre O-ring by projections, and fit into recesses in the one of the components.
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Title: S e a l i n g s y s t e m P a t e n t number: U S 5 7 0 1 7 9 7 Date: 3 0 t h D e c e m b e r 1 9 9 7 Inventor: Frank M o h n Assignee: F r a m o E n g i n e e r i n g A piston reciprocally moving within a cylinder is often exposed to different fluid p r e s s u r e s on its two opposed sides. This difference in pressure gives a tendency for leakage between the piston and cylinder wall, of fluid from the higher p r e s s u r e side into the lower p r e s s u r e side. Such contaminating leakage can be problematic. This invention describes a improved sealing system for a piston reciprocally moving within a cylinder, and is shown in Figure 1 and Figure 2. The piston head (2), is reciprocally driven within the cylinder (1), by a piston rod (5}, which extends into a motor housing (6). The piston rod is spaced from the cylinder wall to provide a c h a m b e r (7), into which lubricant oil is fed. The improved sealing system is based on supplying higher
Figure I. P a s s a g e s In t h e cylInder h e a d help m a i n t a i n t h e seal.
pressure lubricating oil to a space (18) between the two groups of seal rings (19, 20) at the cylinder head (2). On the piston suction stroke, (to the right as shown in Figure 1), lubricating oil enters a chamber (12), through the passage (14). On the delivery stroke, (to the left as shown in Figure 1), the fluid within this c h a m b e r is pressurised. It is prevented from escaping back down the passage (14), by a n o n - r e t u r n valve (15), and is forced into the gap (18), between the seal rings. This fluid between the seal rings is at a higher pressure than the fluid media on either side, helping to prevent leakage.
17
18 4
--
I
(,.~IL FILM
.
~
"
20C
\
1
I
I
t
I
'I
I [
I I
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[
I /
I
..
20
Figure 2. The lubricant oil is forced b e t w e e n t h e seal rings.
Sealing Technology No. 51
WATER
One piece seal stays in place Title: One p i e c e seal w i t h f a s t e n i n g s e c t i o n and s e a l i n g section Patent number: U S 5 7 1 6 0 5 1 Date: 1 0 t h February 1 9 9 8 Inventors: M Cornea, L Lippert Assignee: M a n n e s m R n n R e x r o t h Passages at the interface between two components, s u c h as a screw hole or fluid conduit joining a valve housing to a block, are usually sealed with O-rings or square rings. These seals are positioned within a gap between the components. However, the rings are rarely secured against loss, and awkward handling of the component can cause them to fall out of the recesses. The inclusion of projections on the axial seal, which are pressed into corresponding holes in the metal piece, can help to maintain the position of the seal. This can result in the sealing portion of the axial seal protruding from the piece, allowing dirt particles to collect between the sealing portion and the sheet metal piece which c~m negatively affect the sealing action. This invention is a modified axial seal, made up of three Orings. TWo outer O-rings are joined to the centre O-ring by projections, and fit into recesses in the one of the components.
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