Multi-purpose valve assembly

A flow control valve in a unitary casing has a seat for a manual stem valve on one side of the valve opening and a seat for a check valve on the other side, the check valve being lightly urged toward closing position against differential pressure in the flow stream and being receptive to external pressure control.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to flow control valves and more particularly to a 
valve used in the inlet or suction line of a compressor between the 
evaporator and the compressor of a refrigeration system. 
2. Description of the Prior Art 
Flow control valves, including check valves, are commonly used in 
refrigerant lines where pressure reversals can cause undesirable reverse 
flow. A check valve may be opened by a portion of the pressure drop which 
causes flow in the line. Various types of check valves are known, such as 
those which close only when flow exceeds a maximum desired rate, 
electrically operated, which require no pressure drop to remain open, and 
remote pressure operated which are subject to a higher pressure source of 
refrigerant. 
The Andersson U.S. Pat. No. 2,069,808 discloses a downstream controlled 
pressure regulator in which the valve stem is centered by a diaphram and 
having a filter in the inlet portion of the valve. 
The Birch U.S. Pat. No. 2,105,876 discloses a downstream water pressure 
regulator having a cylindrical screen mounted between an interior wall and 
the removable cap in the inlet side of the regulator. 
The Le Valley U.S. Pat. No. 2,661,893 discloses a control valve operated by 
external pressure in response to variations in discharge pressure. 
The Robinson U.S. Pat. No. 3,744,751 discloses a check valve whose length 
of travel is controlled by a manual valve. 
The Post et al. U.S. Pat. No. 3,788,776 discloses in FIG. 2 an inlet 
throttling valve which is closed in response to pressure in line 68 and in 
which the spring 56 assists in opening the valve. 
The Hoffman U.S. Pat. No. 4,406,588 discloses a suction regulator for a 
compressor in which full opening of the valve is dependent on discharge 
pressure from the compressor. 
The Laucks et al. U.S. Pat. No. 4,227,380 discloses a combination valve for 
the inlet of a compressor including a manually operable valve, an 
automatically controlled stop valve, an automatically controlled check 
valve, and a strainer on the inlet side of the valve. 
The Hart U.S. Pat. No. 4,473,093 discloses a fluid control valve which is 
operated in response to an external "control" gas pressure. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide in a single housing a manually 
operable valve and an independently operable check valve. 
A further object of the invention is to provide a manually operable valve 
and a check valve in which the check valve may be subjected to pressures 
from external sources to control its operation. 
A further object of the invention is to provide in a valve structure a 
check valve of relatively simple structure and of such construction that 
an external source of pressure may be connected thereto to enable the use 
of a high pressure vapor to add to the seating pressure or to cause 
throttling of the vapor flow, or complete shut-off. 
It is a further object of the invention to provide a multi-purpose valve 
including a check valve in which a vapor strainer is accomodated on the 
outlet side of the valve and which is easily removable and replaceable.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With further reference to the drawing the valve 10 of the present invention 
is disclosed in use with a conventional refrigeration system including a 
rotary screw compressor 11, having an inlet or suction line 12 connected 
to the valve and an outlet line 13 for discharging compressed refrigerant 
through an oil separator 14 to a line 15 having a check valve 16 which 
leads to a condenser 17. Condenser 17 is connected by line 18 to a 
receiver 19 which is connected by line 20 having an expansion valve 21 to 
an evaporator 22 having a discharge line 23 connected to the inlet of the 
valve 10. 
The valve 10 includes a housing 24 having a flanged inlet chamber 25 and an 
oppositely disposed flanged outlet chamber 26. Intermediate the inlet and 
outlet chambers, the central portion of the valve has an interior wall 27 
with an opening 28. 
The wall 27 has an upper seat 29 and a lower seat 30 contiguous to the 
valve opening 28. 
Positioned within the inlet chamber 25 and just above the opening 28 is a 
valve member or button 32 which is rotatably connected by conventional 
means to a valve stem 34 having a threaded portion 35 that is received 
within a cover member or bonnet 36 that is connected to the housing by 
suitable fastening means 37. At its other end the stem is provided with a 
handwheel 38. Rotation of the handwheel is operative to move the button 32 
into and out of engagement with the upper seat 29. 
Beneath the valve opening 28 a sliding button or valve 40 is positioned 
within the outlet chamber 26. A button 40 having a groove 42 with seating 
ring 42' which engages the lower seat of the valve opening 28. In order to 
reduce possible chatter noise at part load compressor operations, the ring 
42' is preferably of a resilient and non-metallic material. The lower 
portion of the sliding button has a shank portion 44 having an internal 
wall or bore 45 with ball bushing 46 and an internal end portion 47. 
The internal wall 45 slidingly receives a shaft 48 having a central bore 
49, the lower end of the shaft being rigidly mounted in end or cover plate 
50 which is connected by fasteners 51 to form the lower portion of the 
housing 10. The shaft 48 is preferably threaded into the cover plate 50 
and is locked in place by a spacer 52 having a threaded portion 53 and 
which serves as a lock nut for the shaft. The spacer is also a guide for a 
spring 54 and extends to the required height to act as a stop for the 
sliding button 40. The spring engages the cover plate 50 at one end and 
the lower end of the shank portion 44 of the button 40 at the other end 
and lightly urges the button into seating engagement. 
A fitting 55 is provided in the lower portion of the cover plate 50, in 
communication with a bore 56 communicating with the bore 49 of the shaft, 
for a pipeline 57 which may be connected for example to the line 15 from 
the compressor downstream of the check valve 16. 
Mounted beneath the portion of the interior wall 27 which defines the valve 
opening 28 is a cylindrical strainer 60 which is received at its upper end 
within the shoulder portion 61 and at its lower end by the guide portion 
62 of the housing. The strainer can be easily removed for inspection and 
replacement by the removal of the cover plate 50. 
During normal operation of the compressor the hand-wheel 38 is operated to 
move the button 32 out of engagement with its seat so as to permit free 
flow through the upper portion of the valve. During start-up of the 
compressor, the action of the spring 54 tending to close the button 40 is 
supplemented by the pressure through the line 57 acting against the end 
wall 47 of the button 40. This is sufficient during start-up to keep the 
valve closed in order to reduce the load on the compressor. However, as 
the compressor passes the start-up condition, the differential pressure 
operating against the button 40 is sufficient to open the valve against 
the combined pressure of the spring and the vapor pressure against the 
wall 47, since the area 47 against which the pressure is applied is 
relatively small in comparison with the area of the upper portion of the 
bowl against which the differential pressure is applied. 
When the compressor is shut down, for a limited time, the pressure in the 
line 57 acting against the area 47 only gradually decreases due to the 
temperature prevailing in the condenser 17, and therefore is sufficient to 
hold the check valve 40 firmly closed. In the case of an extended 
shut-down, the handwheel 38 is operated to close the button 32 against the 
seat 29. 
Obviously the pressure applied within the hollow shaft 48 to the area 47 
may be taken from some source other than that which is illustrated in the 
drawing, in order to add to the seating pressure or to cause throttling or 
complete shut-off of the valve 40.