Abstract of
GB1022599
1,022,599. Mechanical seals. NEW YORK AIR BRAKE CO. April 1, 1964 [April 25, 1963], No. 13364/64, Heading F2B. In a mechanical seal for a swash-plate pump shaft 19, the axially movable sealing member 22 is sealed to the shaft by an I-section ring 11 of elastic material having inner and outer cylindrical sealing surfaces 12 and 13, Fig. 2 (not shown), and a groove 14 in each radial face to form a flexible portion 15. The ring 11 is radially compressed between the member 22 and the shaft. The member 22 is driven from the shaft and also urged into facial sealing contact with a fixed sealing member 21 by a spring 23 having out-turned ends 25 and 25<SP>1</SP> received in radial openings in the shaft 19 and the member 22 respectively. The member 21 is sealed to the housing 18 by an 0-ring 26.
A mechanical seal having coiled spring drive means
Inventor: RAMSAY THOMAS WILSON
Applicant: RAMSAY THOMAS WILSON (CA); RAMSAY & STEIN INC (CA); (+1)
EC:F04D13/02B; F04D29/12P2; (+2)
IPC: F04D13/02; F04D29/12; F16J15/34(+6)
Publication info: GB2323900 - 1998-10-07
Claims
WHAT WE CLAIM IS: -
l An hydraulic engine of the swash 90 plate type including a housing, an integral drive shaft-swash plate unit journalled for rotation in the housing, and a running seal for the shaft positioned adjacent its exit from the housing and comprising a station 95 ary annular sealing member supported by the housing, a co-operating annular sealing member carried by an element which encircles the shaft and which has a wall spaced radially from the outer periphery 100 oi the shaft to define an intervening annular space, means biasing the two members of the seal into engagement, and drive means connecting said element in driven relation with the shaft, the improvement 105 which comprises an elastic sealing ring of generally I-shape in transverse cross section located in said annular space and confined on its inner and outer peripheries by said shaft and said wall, respectively, 110 said elastic ring being separate from said drive means.
2 An hydraulic engine of the swash plate type substantially as herein described with reference to the accompanying draw 115 ings.
MARKS & CLERK, Chartered Patent Agents, Agents for the Applicants.
Abingdon: Printed for Her Majesty's Stationery Office, by Burgess & Son (Abingdon), Ltd -1966.
Published at The Patent Office, 25 Southampton Buildings, London, W C 2, from which copies may be obtained.
1,022,599
Description
PATENT SPECIFICATION
DRAWINGS ATTACHED.
1,022,599 Date of Application and filing Complete Specification:
April 1, 1964 No 13364/64.
Application made in United States of America (No 275,667) on 4 April 25, 1963.
Complete Specification Published: March 16 1966.
Crown Copyright 1966.
Index at Acceptance:-F 2 B( 13 C 2 E 3 A, 13 C 2 F 1, 13 C 2 G 3, 13 C 2 X 1).
M Lt CL:-F 06 j.
COMPLETE SPECIFICATION.
Improvements in Hydraulic Swash Plate Engines.
We, THE NEW YORK AIR BRAKE COMPANY, a corporation of the State of New Jersey, United States of America, located at 230 Park Avenue, New York, New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: -
This invention relates to hydraulic engines i e hydraulic motors or pumps of the swash plate type.
In engines of this kind, the swash plate usually is formed in one piece with the drive shaft and this integral unit is supported by a combined thrust and radial bearing located near the front end of the housing Between this bearing and its exit from the housing, the shaft is provided with a running seal This seal comprises a stationary annular member and a cooperating annular member which encircles and is driven by the shaft Normally the rotary member is cup-shaped and is spring biased into engagement with the stationary member In the past, an elastic O-ring was used to seal the space between the cup shaped member and the shaft, and it was found that these O-rings deteriorated rapidly in service While no-one can be certain of the exact cause of this condition, there is an explanation which appears reasonable It is thought that the eccentric loading on the swash plate produces a lateral displacement of the shaft axis, so that during operation this axis traces an imaginary cylinder and the shaft, in effect, rolls or gyrates within its radial bearing Evidently the cup shaped member of the running seal does not follow this gyratory movement of the shaft, and, therefore, the O-ring is squeezed progressively in the radial direction around its entire circumference during each revolution of the shaft It is believed that this squeezing or working of the O-ring produces sufficient relative movement between its inner and outer surfaces and the mating surfaces of the shaft and cup shaped member, respectively, to cause undue wear and deterioration of the O-ring.
An object of this invention is to provide an improved swash plate pump having a running seal of the type described above which is free from the deterioration problem just mentioned According to the invention, the O-ring used previously to seal the space between the shaft and the rotating part of the running seal is replaced by an elastic ring having an I-shape in transverse cross section Tests have shown that this rather simple change in the conventional structure greatly increases the life of the running seal but, as in the case of the problem itself, the reason for this striking improvement in performance cannot be stated with certainty However, it appears that it probably is attributable to the fact that the I-ring has a flexible web which is disposed between the inner and outer peripheral sealing portions of the ring and which, therefore, may distort under the action of the squeezing forces which are thought to act on the ring Since this flexible web does not bear against any other part of the pump, and it is the portion of the sealing ring which will distort under the action of radially directed compressive loads, it follows that the I-ring can accommodate gyratory motion of the shaft without risk of exposing any portion of its surface to the rubbing action which seems to cause deterioration.
The preferred embodiment of the invention is described in detail with reference to the accompanying drawings in which:Fig 1 is a face view of the preferred sealing ring, Fig 2 is a sectional view, on enlarged scale, taken on line 2-2 of Fig 2, Fig 3 is a partial, axial sectional view of a high pressure hydraulic pump of the swash-type incorporating the I-ring shown in Figs 1 and 2.
As shown in Figs 1 and 2, the sealing ring 11 has inner and outer coaxial, circular cylindrical, uninterrupted sealing surfaces 12 and 13 A semi-circular groove 14 is formed in each of the radial faces of the ring midway between the surfaces 12 and 13 Because of these grooves, the middle section 15 is the most flexible part of the ring and is the first portion to elastically deform when the ring is subjected to compressive forces acting in the radial direction The body of the ring is monolithic and can be made from any suitable elastic material, such as that normally used in 0-rings for hydraulic equipment.
'The relative dimensions of the ring are not thought to be critical so long as the radial distance between the surfaces 12 and 13, i e, the thickness of the ring, is slightly larger than the radial distance between the mating surfaces of the members to be sealed In a typical case, the sealing ring has an internal diameter of 0 612 inches, a radial thickness of 0 103 inches, a sealing surface width of 0 103 inches and a middle section width of 0 050 inches.
Fig 3 shows the I-ring embodied in the running seal 17 of a conventional high pressure, swash plate pump 16 such as disclosed, for example, in British patents Nos 588,614 and 626,218, dated August 11, 1944 and August 26, 1946, respectively.
The running seal assembly 17 employed at the front end of the pump consists of a fixed sleeve member 21 and a movable cupshaped member 22 which are carried by the housing 18 and the swash plate shaft 19, respectively, and which are formed with annular mating sealing faces The spring 23, reacting between the shaft 19 and the back-up ring 24, and having outturned ends 25 and 25 ' which are received in radial openings formed in shaft 19 and cup-shaped member 22, respectively, forms a flexible driving coupling between the shaft 19 and the member 22 and biases the latter into sealing engagement with member 21 The space between the outer periphery of member 21 and the housing 18 is sealed by a conventional 0-ring 26, but the space between the shaft 19 and the inner periphery of member 22 is sealed by the I-ring 11 provided by this invention The thickness of this ring 11 is slightly greater than the radial distance between the shaft and member 22 so that the ring is squeezed initially in the radial direction.
The inner and outer peripheral surfaces 12 and 13, respectively, of ring 11 grip the outer surface of shaft 19 and the inner surface of member 22, respectively Therefore, when shaft 19 gyrates in its radial bearing 27, it is believed that the ring is subjected to a radial force which buckles or distorts the flexible web 15 However, since this distortion of ring 11 will not cause any of its surfaces to rub against adjacent parts of the pump, wear is precluded, or at least minimized, and deterioration of the ring is avoided.
As stated previously, the drawing and description relate only to the preferred embodiment of the invention Since many changes can be made in the structure of this embodiment without departing from the inventive concept, the following claims should provide the sole measure of the scope of this invention.
