Patent Application
20120027509
The present invention relates to a retention system and more particularly to a retention system suitable for use in hydraulic flow systems.
Hydraulic units are used in a variety of applications, including refrigeration systems. Most units consist of a housing with one or more bores in which valves or other components are installed to control the performance of the assembly and control pressure and flow within assembly passageways. The valves need a retention device to hold them in place. The most common types of retention for these devices are threaded sleeves or spools which need to be torqued into place. Due to thermal and vibrational forces acting on flow systems, especially those in the aerospace industry, threaded closures run the risk of becoming loose and backing out. Therefore, secondary retention methods are required to accompany the threaded closures. Some common secondary retention devices used are lock-wire (wire is mechanically attached to the threaded member and locked to another place), locking pellets and locking inserts. While these conventional methods work, they require adequate spatial envelope to fit within a system. In addition, they also place additional constraints on how the system may be set up, as well as adding weight to the system.
A system to retain a sleeve within a housing includes a sleeve, a spring loaded retaining pin which can be moved to be fully within the sleeve, a locking pin to hold the retaining pin within the sleeve when the sleeve is being set into or withdrawn from the housing, and an annular recess in the housing to receive the retaining pin when the sleeve is set in the housing, the locking pin is removed and the retaining pin is pushed outward by the spring. The sleeve is retained within the housing when the spring pushes the retaining pin outward so that the retaining pin engages the annular recess in the housing.
A method of retaining a sleeve within a housing includes inserting a first spring loaded retaining pin into a first blind hole within a sleeve; moving the first retaining pin so that the spring is compressed and the first retaining pin is totally inside the sleeve by engaging a part of the first retaining pin with a tool going though a first slot in communication with at least part of the first blind hole; and inserting a first locking pin into a first locking hole which intersects with the first blind hole so that the first locking pin holds the first retaining pin within the sleeve, compressing the springs. It further includes inserting the sleeve into the housing and removing the locking pin to allow the first retaining pin to engage an annular recess in the housing.
Valve sleeve 12 includes first blind hole 18 and second blind hole 24 in flange 16, extending into flange 16 and parallel with front face 14. Slot 20 is in communication with at least part of first blind hole 18, and first locking hole 22 intersects with first blind hole 18. Slot 26 is in communication with at least part of second blind hole 24, and second locking hole 28 intersects with second blind hole 24. First blind hole 18 holds first retaining pin 30 and spring 40. Second blind hole 24 holds second retaining pin 42 and spring 52. Spring 40 connects to stem 38 of first retaining pin 30 and pushes retaining pin 30 outward from blind hole 18. Spring 52 connects to stem 50 of second retaining pin 42 and pushes second retaining pin 42 outward from second blind hole 24. Blind holes 18, 24 are of sufficient length so that each respective spring can compress and heads 32, 44 of retaining pins 30, 42 can fit entirely within flange 16 of valve sleeve 12. Retaining pins 30, 42 can be made of a metallic material such as steel or aluminum or a plastic, depending on requirements of the system.
As mentioned in relation to
Blind holes 18, 24 are strategically placed in sleeve 12 at positions so that retaining pins 30, 42 can sit totally within flange 16 of sleeve 12 for installation or removal of sleeve 12 from housing 60, and so that when sleeve 12 is set in housing 60, pins 30 and 42 can act together to retain sleeve 12 in place within housing 60. This retention is attained by retaining pins 30, 42 being pushed outwards by springs 40, 52 so that heads 32, 44 engage annular recess 62 in housing 60.
Through the use of spring loaded pins which can retract to fit entirely within blind holes in a sleeve, the retention system of the current invention can securely hold a valve sleeve in place within a housing without the need for secondary retention systems which may take up additional space, weight, block some flow within the system and/or add other constraints to the system. In past systems, threaded closures were often used to retain valve sleeves and spools within housings. Because many flow systems are subject to thermal and vibrational forces, especially those in the aerospace industry, the threaded closures ran the risk of becoming loose and backing out. Therefore, secondary retention methods were required. These included such things as lock-wire, where wire is mechanically attached to the sleeve and locked to another place. Other methods of secondary retention used are lock pellets or locking inserts which may impede flow. The current invention retains a sleeve within a housing without the need for a secondary retention system and the additional constraints added by the secondary retention system which the torqued retention systems require.
Tool 66 goes into slot 20, engages neck 34 of retaining pin 30, and moves pin 30 further into blind hole 18. This movement of pin 30 compresses spring 40 and moves head 32 of pin 30 within flange 16 of sleeve 12. Once head 32 of pin 30 is within flange 16 of sleeve 12, first locking pin 54 can be inserted into locking hole 28 (which intersects with blind hole 18). Tool 66 can then be removed from slot 20, and locking pin 54 (in locking hole 28) blocks head 32 of spring 30 from moving outwards towards housing, and therefore keeps spring 40 compressed and pin 30 entirely within sleeve 12. The same procedure can be used to compress spring 52 and retain pin 42 within blind hole 24 using locking pin 42.
As seen in
Pipe fitting 68 is welded into housing 60 to bring pipe fitting 68 and sleeve 12 into fluid flow communication. Sleeve 12 is retained within housing 60 by heads 32, 44 of pins 30, 42 being pushed outward (by springs 40, 52 acting on pins 30, 42, see
As can be seen in
In summary, the retention system described herein is a simple and small means to retain flow controlling assemblies within a housing through the use of blind holes with springs, retaining pins and an annular recess in the housing which also allows easy insertion and removal of the sleeve from the housing. The easy insertion and removal comes from the retaining pins and springs sitting in the blind holes, and the retaining pins being able to be moved completely into the blind hole by a tool engaging the retaining pin neck through a slot in communication with at least a part of the blind hole, and the retaining pin being able to be retained in that position with an easily removable locking pin inserted a locking hole, allowing the sleeve with retention system to be easily inserted, removed and reused. This design can reduce or eliminate the need for additional closures and retention means, and add more flexibility into design of the overall system. The smaller size also reduces the weight of the system, resulting in economic benefits.
While the invention has been discussed mostly in relation to including two spring loaded retaining pins, it can include only one spring loaded retaining pin or three or more spring-loaded retaining pins to hold the valve sleeve in place depending on the requirements of the system. The spring-loaded retaining pins can also have a different configuration than those shown in
While the invention has been discussed mostly in relation to setting a valve sleeve within a housing, it could also be used to retain a closure, a static spool or other mechanisms in place within a housing, a bore or another structure in which they sit. It is intended mainly for unidirectional flow systems, but can withstand reduced loading in bi-directional flow systems. The system may be used as part of a hydraulic flow system in an aerospace application.
While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
