Pumps – Expansible chamber type – Having pumping chamber pressure responsive distributor
Reexamination Certificate
1999-08-19
2001-05-08
Thorpe, Timothy S. (Department: 3746)
Pumps
Expansible chamber type
Having pumping chamber pressure responsive distributor
C417S571000, C137S855000, C137S015190, C029S890129
Reexamination Certificate
active
06227825
ABSTRACT:
BACKGROUND OF THE INVENTION
A membrane valve used more often in the area of refrigeration, and notably used in hermetic and/or semi-hermetic compressors which use an appropriate gas thus promoting the refrigeration effect is provided, allowing the above mentioned gas to be transferred from one chamber to the other, according to a pre-determined frequency as illustrated in
FIGS. 1 and 2
, when utilized in conjunction with a piston.
At the present moment, there exists an extensive variety of membrane valves, generally made of high carbon or stainless steel which, although presenting several manufacturing variations, have a common feature, a manufacturing process of stamping followed by tumbling, resulting, as illustrated in
FIG. 9
, in a monolithic structure, or a single part (A).
In a first manufacturing concept, a single part (A), generally made from a substantially thin metallic plate, a series of openings are produced, which externally define holes (B), with diverse functions, with at least one of such holes destined to the exhaust valve and the rest to the locking in place and assembly of the valve on the body of the head of a specific compressor and, internally defines, at least one cut or elongated opening (C
1
), which basically extends itself around the internal side of the body (A), defining at least one membrane (C), in
FIG. 9
, of any shape as in the tear-shaped example. Then, the body (A), which takes on the functions previously mentioned above, and at least one membrane, is subjected to an operation of rounding the corners by stamping, in-such a way as to avoid the concentration of tension points and the consequent formation of cracks upon operation.
As such, according to the first concept of the manufacturing process pertaining to the state of the method, the membrane valve is defined by at least one cut or elongated opening in a single part (A), in such a way that the membrane (C) continues to integrate the part (A) after punching, and thus presenting a series of disadvantages, as explained in the details to follow.
Generically, in regards to the dynamics of the operation, the membrane valves are comprised of an external section to be attached to the housing of the body of a compressor and at least one internal sections (membrane or reed) free to move (oscillate) in relation to the first sections and positioned over an area which is the intermediate point between the fluid entry duct and a suction chamber and which transfers such fluid to a chamber equally furnished with an exhaust valve. In this manner, at least one of the above mentioned central sections oscillates in accordance to the behavior of the said chamber and, in this condition, the exhaust valve is closed. In a following stage, where the fluid is compressed into the chamber, the membrane valve closes, while the exhaust valve is opened thus transferring the fluid to another duct, with the piston of a hermetic compressor providing the suction and transfer functions.
To satisfactorily execute the sequence of the operations described above, the membrane valves require certain manufacturing characteristics which, when present in larger numbers, are more adequate for its operation.
The first of such characteristics is the existence of the smallest possible radial gap (E) between each elongated opening and its respective membrane, basically around the central section of the body (A), in such a way that, from one side, it allows for freedom of movement of the membrane and, from the other side, little or no gas is retained around it, but is effectively transferred from one chamber to the other. Although the volume, which is usually filled by gas between the membrane and the rest of the body, is relatively small, considering that the body (A) is generally made of a substantially thin plate and, consequently, the quantity of gas stored within it is also a small amount, but, upon multiplying the same quantity of gas by the frequency of the typical operation of a medium size compressor of around 3,600 oscillations per minute, the quantity of the undesirably stored gas becomes considerable, causing a negative result on the efficiency of the assembly's operation, for the gas retained in it does not refrigerate. This situation becomes even more complicated in the case of semi-hermetic compressors, for in these, the oscillation of the reeds are considerably faster, mainly due to the fact that such type of compressor is widely used in several vehicles, in which the rotation is variable and may easily go over the 10,000 RPM range. In existing membrane valves, it is not always possible to obtain a reduced gap (E) between the membrane and the rest of the body for, according to its manufacturing process, it is necessary that a stamping (puncturing) tool be manufactured with reasonable resistance and thickness, which causes the production of a radial gap (E) of around at least 3 times the thickness of the plate.
Another desirable characteristic in this type of valve is the presence of comers which are softened or rounded at the edges of the body (A) and of the membrane (C) at the extension of the gap (E), in order to avoid tension accumulation due to frequent axial flexing of the membrane (C) during operation. Even if the radial gap (E) is somewhat elevated, as explained above, these edges do not present satisfactory softening after being tumbled in a barrel, for the abrasive necessary for the tumbling cannot satisfactory penetrate the gap (E), resulting in a less desirable finishing.
A third and last desirable aspect is the low cost of this type of valve, considering that it is part of a highly competitive market segment. It can be noticed from the operation described here, that the membrane (C) is the most frequently used part of the valve (A) and therefore, would need to be build out of a superior material, the opposite of the rest of the body (D); which acts solely as an assembly support and/or spacer and could be build of less expensive materials. However, considering that this manufacturing concept is based on the stamping of the valve into a single part, all of it should, therefore, be made of a superior, expensive material, even for the parts not subjected to great mechanical use.
In order to solve the above-mentioned problems the technical condition includes different processes, all of which were created so that the membrane valve is manufactured in two distinct parts, such as described in the Brazilian document PI 9.604.645-7 of Dec. 3, 1996, “PROCESS FOR THE MANUFACTURING OF A MEMBRANE VALVE FOR THE TRANSFERRING OF FLUIDS AND A MEMBRANE VALVE”, with its construction, as per the illustration of
FIG. 8
, elaborated to handle different objectives, among which are highlighted:
1. the creation of a membrane valve in two distinct parts, one making up the body or part (D) and the other making up the reed (C) with both parts, however, kept together by an adhesive tape (F);
2. the radial gap (E) between the corresponding edges of the two parts is substantially reduced to less than 3 times the thickness of the thin plate used in the body (D), and may be at least 0.05 mm, favoring the compressor's output, since the quantity of gas retained in the gap is insignificant;
3. the increase of the service life of the puncturing tools used in the construction of the bodies (C) and (D), and especially the opening (C
1
), for punctures, which are more resistant than the ones on thin walls typical of the previous technique, may be used;
4. reduction of the cost of valve manufacturing for it becomes possible to use expensive materials only in the main parts or reed (C);
5. improves the service life of the valve in question, due to the increase of its wear resistance, created by the integral rounding of all the related corners, for the part (C) will have perfect corners for the abrasive may reach them adequately;
6. increases the versatility of the process, allowing for investment reduction in raw material stocking and speeding up production, due to the versatility of the assembly obtained from standardizing one single bo
Barnes Group Inc.
Solak Timothy P.
Thorpe Timothy S.
Vickers Daniels & Young
LandOfFree
Two part reed valve and method of manufacturing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two part reed valve and method of manufacturing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two part reed valve and method of manufacturing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2542567