As it is known by technicians on the art, reciprocating compressors comprises electromechanical equipment capable of compress certain gases as work fluids. The reciprocating compressors used in cooling systems are specially capable of compressing coolants.
Among a plurality of subsystems and components that integrate a reciprocating compressor, it is highlighted—according to the invention in question—the valves system, which is composed by valves capable of control the fluid flows that are sucked and discharged by the compression mechanism of the compressor.
Generally, valves arrangement of reciprocating compressor is composed by at least one suction valve (disposed beneath plate-valve, inside the compression cylinder of the compression mechanism) and at least one exhaust valve (disposed over the plate-valve, inside the exhaust chamber of the head of the compression mechanism of the compressor). Valve arrangements of this kind of compressor are broadly known by technicians on the art.
Specially, and in view of the small size hermetic reciprocating compressors, normally applied in cooling systems, it is common that the valves which integrated the valves arrangement comprises reed valves, that is, valves defined by a flexible metallic foil, which have one of it ends fixed (in a fixed element, by a support and/or fixing means) and another moving end, this being generally aligned with the suction or exhaust port by which exists flow of the work fluid. Reed valves also are extremely known by technicians on the art.
Furthermore, it is still known that some valve arrangements belonging to the current state of the art comprises, beyond the “main” valve (which can be a suction valve or an exhaust valve, or both) at least one auxiliary valve. The use of the auxiliary valve is more common in set with exhaust valves, but not limited to this. The auxiliary valve is assembled between the main valve and the exhaust stop, which is a rigid limiter of the valve movement path. An auxiliary valve infers a spring effect on the main valve, from specific openings of the main valve. For the opening process, by reaching the contact height with the auxiliary valve, the set slows, due to higher rigidity of auxiliary valve, before the contact with the stop, avoiding high impact speeds that can fracture the valve. The quantity of movement of the main valve is stored on the auxiliary valve, with spring force, which is returned accelerating the main valve for the closing process avoiding gas reflux of the exhaust chamber for the compression chamber, which degrades the compressor efficiency. In a general way, either for suction valves or exhaust valves, since they are reed valves, is common the use of auxiliary valves, this also comprises reed valves.
However, and considering that the main valve and the auxiliary valve have at least one end capable of moving, being this end free or supported, can be observed some problems related to moving dynamic between such valves.
In general lines, such problems refer to basically the occurrence of wear on the fixing region of main and auxiliary valve. On the limit of the functional and fixing regions, here called crimping lines where the valve flexion occurs, there is an intense and frequent micro-displacement related and tangential between the main and auxiliary valve, which is a common wear mechanism. This process is aggravated if the fixing means exerts compressive tension concentrated on this limit region. This configuration is usually found in reciprocating hermetic compressors, which eventually may fail depending on the biasing applied to the valve system, being this the intense relative movement and normal strength of fixing near the valve flexion region.
The current state of the art comprises some constructive solutions intended to mitigate this problems, among them highlights the solutions described on patent documents JP2013177820 and WO2007116989.
Patent document JP2013177820 describes an arrangement of valves fundamentally integrated by a main valve, an auxiliary valve, a valve stop and a fixing means. On this arrangement the main valve is spaced from the auxiliary valve by means of a spacer element, which is also fixed by fixing means. Said spacer element prevents the valves to have physical contact between them on the region that they are fixed (fixing means region), reducing, consequently, the occurrence of wear on the valves flexion region. However, introducing an additional body—the spacer element—does not eliminate all negative aspects, which also keeps the fixing strength over the flexion areas. From a constructive point of view increases the complexity and cost by the addition of a component of the valves system.
Patent Document WO2007116989 describes a valve arrangement fundamentally integrated by a main valve, an auxiliary valve, a valve stop and a fixing means. On this arrangement the auxiliary valve is particular in view that shows on the fixing region appendix stamped which works as elastic spacers of spring effect. The valve stop has a protruding portion that on being pressed by the cylinder lid presses the auxiliary valve on the spacers region which transmits part of the fixing strength, but keeping certain spacing. This spacing prevent that the valves have physical contact between them on the region that they are fixed (fixing means region), reducing, consequently, the occurrence of wear on the valves flexion region. However, using an auxiliary valve and stop as described on document WO2007116989, because involves a more complex construction, requests production processes more complexes and costly.
This way, and having in mind that the current state of the art lacks of simple solutions capable of reducing reliability problems related to wear on valves arrangements provided by at least one main valve and at least one auxiliary valve, emerges the invention in question.