Variable size coupling

Apparatus for forming a tight seal between a coupling and a tube of variable sizes. A cylindrical housing defining an opening therein is provided such that a plurality of jaws having gripping teeth and gear teeth are mounted within the housing by being rotatably secured on a pin. A sleeve having rack teeth for engaging the gear teeth of the jaws is provided for rotating the jaws such that the inward extension of the gripping teeth may be varied. A piston having a seal mounted thereon and a projecting member extending therethrough is slidably maintained within the cylindrical opening such that a joint may be formed between the tube and the coupling. The piston defines together with the housing an expansible chamber which may be filled with a pressurized fluid to move the piston against the tube to assure a tight seal. A limit switch may additionally be provided such that if the gripping teeth do not properly engage the exterior of the tube the piston will be displaced sufficiently to engage the limit switch.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to couplings adapted to be fitted to join two 
tubular members. More specifically the present invention concerns a 
coupling for securing various sized tubes to a conduit to form a tight 
seal therebetween. 
2. Prior Art 
Within the air conditioning and refrigeration industry it is desireable to 
test compressor assemblies salvaged from used air conditioning and 
refrigeration units to ascertain the condition of the compressor. Upon air 
conditioner malfunction and replacement the compressors from the units are 
forwarded to a rebuilding facility where on a large volume basis these 
compressors may be tested for several factors including whether or not 
they are electrically shorted, will meet pumping capacity and other 
operating characteristics. 
When this compressor assembly is removed from a unit normally the tubing 
connections between the compressor and the rest of the air conditioning or 
refrigeration unit are mechanically severed. Additionally these 
compressors are of varying capacities such that the suction and discharge 
lines for these compressors also vary within a range of sizes. 
Consequently to enable a single coupling to be connected to these various 
size tubes leading from the compressor it is necessary that the coupling 
be adapted to form a tight seal with a range of tube sizes. 
The variable size coupling described herein is specifically designed such 
that tubing having a range of internal and external diameters may be 
sealed in the coupling for testing and thereafter be removed. The coupling 
additionally has means to provide for a tight seal notwithstanding uneven 
mechanical deformation of the tubing when it is removed with the 
compressor from the unit. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a variable size 
coupling. 
It is a further object of the present invention to secure various size 
tubes to a conduit to form a tight seal therebetween. 
It is another object of the present invention to provide a coupling which 
is adapted to connect variable size tube to a conduit such that a pressure 
tight seal is formed for testing purposes. 
It is a still further object of the present invention to provide a coupling 
which is easily adapted to secure a tube of varying diameter inserted 
therein subsequently to allow removal of the tube from the coupling. 
It is another object of the present invention to provide a coupling having 
pressure means for forming a tight seal with variable size tubing and 
further having failsafe means such that if a tight joint is not formed the 
pressure testing device may not be operated. 
It is a yet further object of the present invention to provide a reliable, 
safe, easy to manufacture and economical coupling for use in a compressor 
testing device for joining various size tubing from compressors to testing 
apparatus. 
Other objects will be apparent from the description to follow and the 
appended claims. 
The preceding objects are achieved according to the preferred embodiment of 
the invention by the provision of a housing defining a cylindrical opening 
therein. A plurality of jaws having gripping teeth and gear teeth are 
rotatably mounted within and spaced about the opening in the housing. The 
gripping teeth of the jaws are spaced at varying radial distances from the 
axis of rotation of the jaw such that depending upon the rotational 
position of the jaw the distance between the axis of rotation and the 
gripping teeth will be varied. The tube to be secured is inserted within 
the opening between the gripping teeth of the jaws. 
A sleeve having rack teeth is slidably mounted about the housing such that 
the rack teeth of the sleeve engage the gear teeth of the jaws. A 
passageway extends thru a piston in slidable engagement with the interior 
of the opening in the housing, the piston having a seal mounted thereon. 
Hydraulic means are provided for supplying a pressurized fluid to an 
expansible chamber formed by the piston and the housing such that upon 
insertion of the tube against the seal, the tube is secured by the 
gripping teeth and the hydraulic means is used to force the piston having 
the seal thereon against the tube to form the tight joint. A limit switch 
having a contact button is mounted to the piston such that should the tube 
not be secured by the gripping teeth of the jaws the limit switch will be 
engaged when the piston has traveled the predetermined distance.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The embodiment as described herein concerns a variable size coupling for 
use with compressor testing apparatus to ascertain the condition of a 
compressor. It is to be understood that this coupling finds applicability 
to all types of couplings wherein a variable sized tube is joined to a 
conduit. 
Referring now to FIG. 1 it can be seen that coupling 10 has tube 80 
inserted therein. Tube 80, which may be refrigerant line connected to a 
compressor, is a variable size tube from the compressor to be tested which 
is to be coupled with a conduit. Tube 80 is inserted within cylindrical 
opening 20 defined by housing 12. Sleeve 14 is slidably mounted on housing 
12 interior the ends thereof. Hydraulic circuit 26 extends outwardly from 
housing 12 to provide pressurized fluid to the appropriate regions 
therein. Body 60 is mounted on a piston with spring 44 such that as the 
piston moves within housing 12 body 60 moves relative thereto. Limit 
swtich 48 is shown mounted on housing 60 such that it will contact washer 
46 mounted to housing 12 upon sufficient displacement of the piston. 
In FIG. 2, a cross sectional view of the coupling shown in FIG. 1, it can 
be seen that jaws 18 are mounted about the interior of first cylindrical 
opening 20 and have gripping teeth 28 extending inwardly therefrom. Jaws 
18 are mounted for rotational movement on pin 30 and additionally have 
gear teeth 32 extending in one direction and gripping teeth 28 extending 
in the opposite direction. The gripping teeth are arranged such that they 
are radially offset from the axis of the rotation of the jaws. 
Consequently upon rotation of the jaw the inward extending distance of the 
furthest gripping tooth from the axis varies. It can be further seen in 
FIGS. 2 and 3 that three jaws are spaced about the interior of the first 
cylindrical opening 20. 
Sleeve 14 is slidably mounted about housing 12. Rack teeth 34 are mounted 
on the interior edge of sleeve 14 in gear tooth engagement with gear teeth 
32 such that a sliding movement of sleeve 14 produces a rotation of jaws 
18. Spring 16 is provided to bias the sleeve relative to the housing to 
maintain the gripping teeth of the jaws extended inwardly. 
Housing 12 defines both a first cylindrical opening 20 wherein the jaws are 
mounted and a second cylindrical opening 22 having piston 37 slidably 
mounted therein. Piston 37 has seal 38 mounted on the end thereof and 
passageway 36 extending longitudinally therethrough. Piston 37 and housing 
12 define an expansible chamber 24 connected to the hydraulic circuit 26 
such that upon the addition of hydraulic fluid to the expansible chamber 
the piston will move in reference to FIG. 2 from right to left. 
O-rings 40 and 42 are provided between the piston and the housing to secure 
the hydraulic fluid within the expansible chamber. Piston abutment 54 is 
designed to contact housing abutment 56 when the piston is in the 
rightmost location. Spring 44 acting through washer 46 which abuts housing 
12 biases piston 37 in the left to right direction in reference to FIG. 2. 
Passageway 36 extends through piston 37 outwardly from seal 38 within 
projecting member 35 such that the tube to be joined therewith is inserted 
over the end of projecting member 35. The projecting member forms part of 
passageway 36 between a compressor to be tested and the testing equipment. 
The end of projecting member 35 is tapered to guide the tube from the 
compressor to the appropriate location. 
Piston 37 extends outwardly through the second cylindrical opening 22 and 
has mounted exterior of housing 12 body 60. Body 60 has a recess therein 
in which part of spring 44 is maintained. Mounted to body 60 are limit 
switch 48 having a limit switch button 50 and wires 52. Limit switch 
button 50 is located such that upon sufficient movement of the piston in a 
right to left direction the button will contact washer 46 and activate 
limit switch 48. The end of piston 37 is threaded such that conduit 39 
connected to the compressor testing equipment may be secured thereto. 
The relationship of jaws 18 in reference to each other may be seen in FIG. 
3 which is an end view of the coupling. It can be seen therein that pins 
30 are mounted to housing 12 and have jaws 18 mounted for rotation 
thereabout. Projecting member 35 is shown at the center thereof as is seal 
38 adapted to receive the end of the tube to be connected thereto. 
Additionally hydraulic conduit 26 may be seen in FIG. 3. 
Operation 
The tube which is desired to be connected to the conduit herein for testing 
is inserted into the first cylindrical opening 20 until it engages seal 
38. Prior to insertion of the tube the sleeve 14 is displaced from right 
to left such that the gripping teeth of the jaws are rotated outwardly 
providing a large diameter opening for the tube to be inserted therein. 
Once the tube abuts seal 38 such that the end of projecting member 35 is 
interior the end of the tube then sleeve 14 is moved from left to right 
such that the gripping teeth of the jaws are rotated inwardly to contact 
the exterior surface of the tube. Spring 16 acts to maintain the sleeve in 
position such that the gripping teeth are continually engaged with the 
tube. The gripping teeth are angled to prevent the tube from being 
disengaged from the seal. 
Once the sleeve is released and the gripping teeth secure the tube then 
hydraulic or other pressurized fluid is supplied through hydraulic conduit 
26 to expansible chamber 24. The pressurized fluid acts on piston 37 to 
move it from right to left such that the piston forces the seal against 
the tube end and the seal forces the tube into the gripping teeth. The 
gripping teeth should hold and a pressure tight seal is then formed 
between the seal and the tube end. The hydraulic circuit is arranged such 
that a predetermined pressure is developed against the tube end. 
Should the gripping teeth fail to secure the tube as the piston is moved 
from right to left within first cylindrical opening 20 and second 
cylindrical opening 22 then the piston will continue to be displaced from 
right to left against the action of the spring 44 until such time that the 
limit switch button 50 of limit switch 48 contacts washer 46. Upon contact 
being initiated the limit switch button is depressed actuating the limit 
switch which discontinues coupling operation. 
After the tube is secured and after the various compressor testing 
functions are completed the tube is removed by bleeding off the hydraulic 
pressue such that the spring 44 causes the piston to move from left to 
right back to its initial position as shown in FIG. 2. Thereafter sleeve 
14 is slid from right to left disengaging gripping teeth 28 of jaws 18 
such that the tube may be removed without further impediment. Sleeve 14 is 
then released and returns to its original starting position or another 
tube for testing may be inserted immediately therein. 
This coupling has been designed for use with a compressor testing device 
such that various size tubes used as discharge and suction line tubes of a 
compressor may be connected to the compressor testing machine therewith. 
It is to be understood that this coupling has like applicability in other 
forms of connection devices. 
The invention has been described herein with reference to a specific 
embodiment thereof. It is to be understood that modifications and 
variations can be made within the spirit and scope of the invention.