Control valve to be employed for refrigerator and air conditioner
BACKGROUND OF THE INVENTION 
     This invention relates to a control valve, including a pressure control valve to be employed for refrigerator and air conditioner, an evaporation temperature control valve and etc. A control valve of the prior art, for example a pressure control valve, consisting of a valve proper, an inlet coupling and an outlet coupling, employs some means, such as O rings or welding, for keeping parts such as valve means under the airtight position. Further, control means is exposed to outside. Therefore, many kinds of parts are necessary, causing a failure requiring many steps in assembly. Further, since there are many parameters causing unsatisfactory airtight position, observed is a tendency to be readily influenced by the ambient pressure. 
     SUMMARY OF THE INVENTION 
     This invention is aimed at providing a control valve to be employed for refrigerator and air conditioner, eliminating failures inherently unavoidable in cases of control valves of the prior art. 
     A general object of this invention is to provide a control valve comprising, in combination, a tube which is fabricated by pressing or drawing to form a cartridged and airtight valve body together with outlet and inlet couplings after being assembled with a valve means and a valve means, which is to be cartridged in the above tube, comprising a pressure monitor and a valve to work in response to the pressure monitored by the above mentioned pressure monitor. 
     Another object of this invention is to provide a pressure control valve comprising, in combination, a tube to be fabricated by pressing or drawing to form a valve body together with outlet and inlet tubes after being assembled with a valve means, which is of a cartridge construction, comprising a pressure monitor having a diaphragm of which the internal pressure is kept in constant by means of containing inert gas in the diaphragm or by utilizing a spring for monitoring the outlet pressure of evaporator and a valve means for control of the flow of refrigerant by opening or closing a valve in response to the outlet pressure of evaporator monitored by the pressure monitor mentioned above. 
     A further object of this invention is to provide a pressure control valve comprising, in combination, a tube to be fabricated by pressing or drawing to form a valve body together with outlet and inlet tubes after being assembled with a valve means, which is of a cartridge construction, provided with an evaporation temperature monitor having a diaphragm in which active gas is contained and a valve means for control of the flow of refrigerant by means of valve action in response to the change in pressure of the active gas monitored by observing the evaporation temperature of the active gas. 
     The present invention will be explained more particularly with reference to the accompanying drawings where: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a control valve comprising, in combination, a diaphragm containing inert gas and a pilot valve directly connecting with the diaphragm; 
     FIGS. 2 and 3 are cross-sectional views of control valves comprising, in combination, a diaphragm utilizing a spring rather than inert gas contained in it; 
     FIG. 4 is a cross-sectional view of a control valve utilizing a pilot valve different from the shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Firstly, explanation will be made for the case shown in FIG. 1. A valve proper (1), being placed on top of a fitting base (2) with a short cylindrical shape, constitutes, as one body, a seat (3) with a cylindrical shape which constitutes a pilot chamber (3a). A monitor means (4) is placed on top of the seat (3). 
     The upper chamber of the monitor means (4) divided by a diaphragm (4a) contains inert gas, supplied through a capillary tube (4d), of which the internal pressure is kept at a constant. The capillary tube (4d) is sealed by pinching afterwards to keep the diaphragm (4a) airtight. A pilot valve (5) directly connected with the diaphragm (4a) has a function to open or close an orifice (6) of the pilot chamber (3a). The monitor means (4) is connected with the inlet tube, to be discussed later, through a pressure equalizing hole (4b) of a diaphragm chamber (4c). The seat (3) is provided with a piston (8) equipped with a spring (7). The piston (8) is allowed to shift along the seat (3). Further, the piston (8) is provided with a hole (9) through which the inside of the piston (8) is connected to a tubular fluid flow passage (10). 
     The spring (7) is placed along the internal surface of the skirt of the piston (8). The spring (7) is placed between a washer fitted to the fitting base (2) by calking and a stage portion formed at the upper portion of the skirt mentioned above. 
     An orifice (12) is placed on top of the piston (8). The valve proper (1) capable of the valve activities as discussed above is, as one body, inserted to a tube (13) before being fitted with the fitting base (2) by means of spinning (13a) and being fabricated to form the inlet tube (13b) and outlet tube (13c) by means of pressing or drawing. 
     The activities of the control valve, discussed above, to be utilized as an evaporation pressure control valve will be explained below. When the evaporation pressure is applied at the lower surface of diaphragm of the monitor means (4) through the inlet tube (13b) and the pressure equalizing hole (4b), the pressure applied at the lower surface of the diaphragm is equal to the pressure of inlet tube (13b), so that the orifice (6) is not closed by the pilot (5). Thus, when the orifice (6) is open, the pressure in the pilot chamber (3a) inside the seat (3) is equal to the pressure of inlet tube (13b), so that the piston (8), being pushed downward by the pressure, stays at the lower end to keep the hole (9) at the open position. As a result, refrigerant is allowed to flow into a compressor through the outlet tube (13). 
     However, should the pressure of inlet tube (13b) become less than a specific value, the pressure applied at the lower surface of the diaphragm of the monitor means (4) also becomes less than a specific value, since the pressure is identical to that in inlet tube (13b) through the pressure equalizing hole (4b). Thus, the inert gas pressure applied above the diaphragm (4a) pushes the diaphragm (4a) downward to make the pilot valve (5) to close the orifice (6). Therefore, being sucked by a compressor, the pressure in the pilot chamber (3a) reduces. 
     Then, once the pressure in the pilot chamber (3a) reduces below the pressure of the spring (7), the spring (7) pushes the piston (8) upward. When the piston (8) is pushed upward, the piston hole (9) is covered by the piston wall, resulting in closure of the fluid flow passage through the tubular fluid flow passage (10). When the tubular fluid flow passage (10) is closed, the pressure in inlet tube (13b) increases again. 
     Should the pressure in inlet tube (13b) increase beyond a specific value, the diaphragm (4a) is pushed upward by the pressure passing through the pressure equalizing hole (4b). As a result, the pilot valve (5) opens the orifice (6) to increase the pressure in the pilot chamber (3a), which pushes the piston (8) downward against thrust of the spring (7), causing the relative position of the tubular fluid flow passage (10) and the hole (9) to make an opening condition. Therefore, subject to existence of a satisfactory refrigerant pressure in the inlet tube (13b), the fluid flow passage returns to a full opening position to keep the evaporation pressure at or above a specific value. 
     A pressure control valve of the prior art, utilizing a spring, controls the pressure of an evaporator by means of adjusting thrust of the spring. Accordingly, this requires many kinds of parts and causes a failure that the influence of the ambient pressure is unavoidable. 
     This embodiment is provided with a monitor means having a diaphragm containing inert gas to keep the diaphragm internal pressure at a constant rather than having a spring, and monitoring the pressure of evaporator at the opposite surface of the diaphragm, it controls the flow of refrigerant by opening and closing of a valve in response to balance of the pressure. 
     Accordingly, available is a pressure control valve of which the control pressure is adjustable by means of adjusting the pressure of inert gas contained in the diaphragm, of which the kinds of parts are fairly limited and which is hardly influenced by the ambient pressure. 
     In any case, since the control valve is formed by fabrication of a tube (13), after being inserted with a cartridged valve means comprising a monitor means having a diaphragm and a valve operating in response to the monitor means, no possibility is observed for an unsatisfactory airtight condition, less kinds of parts are required and less steps are required in assembly. Further, since the valve means is inserted, as one body, in the tube, observed is another feature that the ambient pressure hardly be effective to the accuracy of control. An easy fabrication is feasible for the cartridged control valve by utilizing aluminum for the seat, piston, washer and tube. 
     Secondly, the embodiment shown in FIG. 2 is completely identical to that shown in FIG. 1 except for the construction of monitor means. In other words, a spring (14) rather than inert gas is utilized for the diaphragm. A spring chamber (15) is placed on top of the diaphragm chamber. An adjusting spring (14) is placed between a supporter of the diaphragm (4a) and a supporter of the spring (17) movable upward and downward by means of an adjusting screw (16) screwed on top of the spring chamber (15). In the case shown in FIG. 2, an O ring is provided between the adjusting screw (16) and the spring chamber (15) to prohibit the refrigerant pressure from being brought into the spring chamber (15). The operation of this device is identical to that shown in FIG. 1 excepting the adjustment is to be made with a spring rather than the pressure of gas contained in a diaphragm. 
     Thirdly, the embodiment shown in FIG. 3 utilizes an adjusting spring as does in the case of FIG. 2. This embodiment is, however, provided with an adjusting screw (16) screwed directly on the spring chamber (15) rather than on the supporter of spring (17) as in the case of FIG. 2 and with a screw (16) of which the lower end is supported on the supporter of spring (17). In this case, a binding agent or solder is applied between the outer surface of spring cylinder (15) and the adjusting screw (16) to prohibit the refrigerant pressure from being brought into the spring chamber (15). 
     Although the explanation is made on the assumption that the monitor means is made of a diaphragm for the above embodiments, the identical effects can be expected for the cases where the monitor means are made of bellows. An evaporation temperature control valve can also be formed in the similar manner. 
     Fourthly, the embodiment shown in FIG. 4 relates to the evaporation temperature control valve provided with a spring (14) between a supporter of diaphragm (4c) and a diaphragm (4a) provided with a pilot valve (5) directly connected with the diaphragm (4a) by means of a rod. The supporter of diaphragm (4c) is fitted on a seat (3) through a valve seat (19) provided with an orifice (6) which is opened or closed by means of the pilot valve (5). The orifice (6) is connected with an inlet tube (13b) through an inlet channel (18) of the valve seat (19). Active gas is contained in an upper chamber of the diaphragm of the monitor means. A capillary tube used for supply of active gas is pinched thereafter for keeping airtight for the diaphragm. Except for the mentioned above, no difference is observed for construction of this embodiment from that shown in FIG. 1. Accordingly, the same marks are given for the equivalent portions. 
     Explained below is the operation of the control valve: 
     When the evaporation temperature is at a specific value, a pilot valve (5) opens an orifice (6), as shown in FIG. 4. Under this condition, the pressure in a pilot chamber (3a) is identical to that in an inlet tube (13b), causing a piston (8) to stay at the lower end. Since a hole (9) of the piston (8) is kept at the opening position, refrigerant is sucked by a compressor through an outlet tube (13c). 
     However, should the evaporation temperature of the refrigerant become low in the inlet tube (13b), the pressure of the active gas becomes also low, causing the pilot valve (5) to be raised by the thrust of a spring (14) to close the orifice (6). As a result, the pressure of the pilot chamber (3a) reduces, being sucked by a compressor. Then, a spring (7) pushes the piston (8) upward against the downward thrust of the piston, causing the hole (9) of the piston (8) to be covered by the piston wall to close a fluid flow passage passing through the tubular fluid flow passage. Thus, once the tubular fluid flow passage is closed and the pressure and temperature of the refrigerant rises in the inlet tube (13b), the active gas swells to increase the pressure and opens the pilot valve (5) against the thrust of spring (14). When the pilot valve (5) opens, the internal pressure of a pilot chamber (3a) increases to push the piston (8) downward against thrust of the spring (7), making an opening condition for the relative position of the tubular fluid flow passage (10) and the hole (9). Thus, subject to the refrigerant temperature in the inlet tube (13b) beyond a specific value, the fluid flow passage (10) returns to a full opening position to enable the evaporation temperature to stay at or above a specific value. 
     An evaporation temperature control valve of the prior art, monitoring temperature by means of a bimetal etc., controls the evaporation pressure to keep within a specific range, causing a high production cost and slow response speed. 
     This embodiment, however, controls the evaporation temperature directly by means of the valve operation in response to the change in pressure of active gas, causing excellence in the control performance, advantage in production cost and swiftness in response speed. 
     As is clear from the explanation with reference to FIGS. 1 through 4, the present invention relates to a cartridged control valve manufactured by means of fabrication of a tube to form a valve body together with outlet and inlet tubes after being assembled with a valve means, which is of a cartridge construction, comprising a monitor means, a pilot valve, a piston and etc. Since the control valve proper forms one body with the means for access to outside such as inlet and outlet tubes, no possibility can be assumed for an unsatisfactory airtight position. Further, since the control valve proper is assembled in a tube, being completely isolated from the ambient, it can hardly be influenced by the ambient pressure. In addition, since the control valve requires a less kinds of parts, it requires a less steps in assembly.