ES2342547T3 - VALVE, IN PARTICULAR FOR COMPRESSORS. - Google Patents

Abstract

Valve, in particular for compressors, comprising a seat (1) provided with at least one flow way (111), an obturator member (4) able to obstruct said flow way (111) and movable with respect to said seat in a given direction, and means (5) for resiliently stressing said obturator (4), which are able to force said obturator (4) into a given position and are active in the direction of movement thereof; said resilient stressing means (5) comprise at least one cylindrical helical compression spring (5), characterized by the presence, between all the turns and along the entire working length of the spring (5), of inter-turn apertures.

Description

Valve, in particular for compressors.

Background and Summary of the Invention

The present invention relates to a valve, and in particular it refers to a valve for compressors alternative, of alternative type.

Valves of the type commonly used in said compressors are normally automatic valves, comprising a valve body, called the seat, consists on a plate that has a series of channels formed on it axial flow that can be concentric or not. Opening and closing of these channels is carried out by the shutter, an organ that It can consist of a series of elements or a single element. In In all cases, the shutters are subject to the action of elastic stress means, typically compression springs Cylindrical helical metal. The springs remain housed inside a valve body (called "counter-seat"; which consists of a plate in which forms the flows that pass through the channels. The bodies of springs mentioned above may also contain elements of protection of springs that are preferably made in a thermoplastic material and that has the function of eliminating the metallic contact between the spring surface and the parts external metal, such as, for example, body walls envelope formed in the counter-seat or itself shutter.

Most of these springs are of the type of Cylindrical helical or conical helical compression. These springs, which are made of steel rod or wire, they consist of a total number of turns that equals the sum of active laps and non-active laps. Laps no active are in contact with the adjacent turns and also said turns are properly ground at the ends to ensure good axial stability of said spring.

The springs constitute one of the most valve reviews; actually, the high frequencies of opening / closing produce in them and in the parts in contact with the same, wear of nature and variable degree. In accordance with the state of the art, most of said wear, which is produced by the movement of the spring, has been analyzed and defined, and can be classified as follows:

TO)

wear between the outer surface of the spring and the surface of the body cavity, which is eliminated by the introduction of plastic elements that are inserted between the spring and the body;

B)

wear between the lower end of the spring and the support surface of the body cavity, which is removed by the introduction of plastic elements;

C)

wear between the upper end of the spring and the contact surface with the shutter, which is removed by the introduction of plastic elements or by the introduction of plastic shutters.

US 4 612 962 A describes a valve with spring, for example, a check valve or a check valve safety, which comprises a helical spring that works not only to force the valve element towards its seat but also to retain the valve element forming the assembly with The valve.

US 2003/010950 A1 describes a valve for flow control of large cross section with high operating frequency and, in particular, for compressors or the like, comprising an opening device of flow and a closing device, said device comprising opening one or more holes formed on a fixed body that cooperates with said closing device and introduced into the channel of flow, rotating said closing device with respect to an axis perpendicular to the plane on which said fixed body is located, and being equipped with drive means; said device of closure is provided, at least, with a recess in the surface directed to said fixed body, in which a false element is housed or insert, said insert being formed so that it is substantially complementary to said hole of said body permanent.

In GB 1 055 684 A, which is the one considered closer to the state of the art, a annular check valve for piston type compressors, in which a valve element is mobile between a valve plate and a protection The valve element receives the action and guidance of a helical spring resting radially on opposite ends against cylindrical surfaces arranged respectively in the protection and in the valve element. To reduce shocks and wear ensuring a regular seat, at least one end of the spring, where it rests radially, has a finish of mechanization so that it engages intimately. In a modification, an external radial surface of the spring end It engages with a surface directed into the valve. In Another modification, a round wire spring is used.

Despite these improvements, the spring continues being one of the most critical parts of the valve and cause of malfunctions One of the most important problems of these springs is the interference between the turns during the normal valve opening / closing operation, especially with high frequencies. The development of compressors increasingly fast and continued efforts to eliminate the oil in the compressed gas have resulted in an increase of reliability problems of the aforementioned components.

The objective of the present invention is, therefore, in disclosing a valve for compressors in the that the wear characteristics of the springs are optimized in comparison with what is known in the cited documents and in the state of the art, and in which practically the interference problems between all coil turns of the valve, both in rest conditions and in conditions of compression, ensuring a longer life of the compressor and precise operation, even at high frequencies.

The present invention therefore relates to a valve for alternative compressors according to the claim 1.

According to another feature of the valve, according to the present invention, the difference in diameter between the extreme turns, which are conical terminal turns open, and the turns immediately adjacent to those is the double the cross section of the metallic wire that forms the spring.

In a preferred embodiment, the turns extremes have smaller dimensions than the turns immediately adjacent. Advantageously, the valve according to the The present invention can be provided with protective elements that they are preferably made of a plastic material and are arranged inside the housing that receives the spring, to effects of additionally preventing wear.

Brief description of the drawings

Other advantages and characteristics of device, in accordance with the present invention, will be deducted from the following description of an embodiment thereof, which has only non-limiting drawing character, referring to the attached drawings in which:

Figure 1 is a sectional view of a embodiment of the valve according to the present invention;

Figure 2 is a sectional detail of the valve according to figure 1, in another operating configuration;

Figure 3 is a plan view of the spring used in the valve according to the invention; Y

Figures 4A and 4B are two sections of the spring, in conditions of rest and compression, respectively.

Description of the preferred embodiments of the invention

Figure 1 shows an embodiment of the valve, according to the present invention; the numeral (1) indicates the seat of said valve, comprising a plate (101) provided with a series of axial and eccentric through holes (111) that they act as flow guides for the fluid and they have a hole central, axial, through, threaded (201) with which the threaded end (306) of the bolt (6). The plate (101) also has slots (121) that communicate with the through holes (111). The central part of the bolt (6) is also mounted on it the bushing (406) and the plate (2) opposite the seat or "counter-seat", equipped with an axial hole through exchange (302); the seat (1), bushing (406) and plate opposite the seat (2) are fixed together by means of the threaded nut (106) on the threaded end (206) of the bolt (6). The through axial ducts (102) are made in the plate opposite the seat (2).

The shutter (4) is arranged between the seat (1) and the plate opposite the seat (2), being coaxial and concentric with bushing (406) and axially sliding along it by means of its central axial hole (304). The shutter has, formed therein, eccentric openings (104) that are axially displaced with respect to the axial holes (111) of the seat plate (101) (1), these openings being aligned with the ducts (102) formed on the plate opposite the seat (2). The seat (1) and the opposite plate (2) are also joined together by means of the pin (401) that is inserted into the hole blind (301) formed in the plate (101) and passes through the hole (204) of the shutter (4) and enters the blind hole (202) of the plate opposite the seat (2).

The plate opposite the seat (2) is also provided with a cylindrical body (402) within which the cylindrical helical compression spring (5) is arranged, the end turns (105) having a smaller diameter than the turns (205) immediately adjacent to them. The false elements or inserts (412) and (422) are arranged inside the body (402), said false elements being preferably made of a thermoplastic or similar material and having the function of eliminating metallic contact of the spring (5) with the associated body (402). The end wall of the insert (412) presses, due to the action of the spring (5), against the surface of the plug (4) which in the figure has been shown open as a result of the action of the flow of fluid passing through the holes (111) in the seat plate (101) (1). The spring (5) of this figure has been shown compressed inside the body
(402).

Figure 2 shows a sectional detail of the valve according to figure 1; identical parts have been designated with The same numbers. The valve has been shown in this case in closed situation with the shutter (4) that is in contact with the slots (121) of the plate (101) that communicate, as you can see in figure 1, with the holes (111) through which passes the liquid. The spring (5) has been shown in this equilibrium case, expanded compared to conditions shown in figure 1.

Figure 3 shows a plan view of the spring 5 acting on the valve plug (4); such as it can be seen, the extreme expires (105) visible in the figure has a smaller diameter than the spiral (205) adjacent to the same. Figures 4A and 4B, on the other hand, highlight the fact that the presence of the openings between turns, together with the difference in diameter between the open conical end turns (105) and the immediately adjacent turns (205) result in absence of interference of all turns in the entire section of usable work.

The operating principle of the valve, according to the The present invention will be apparent from the following description. The valve of the type shown in figure 1 is normally used in compressors and works with opening and closing frequencies clearly elevated. As a consequence, the elastic means that act on the shutter (4) are subject to considerable wear and this inevitably affects proper functioning from valvule. The spring (5) has characteristics such that ensure that it breaks down considerably less than usual cylindrical helical springs. One of the causes main springs wear issue is associated with the fact that these extreme turns are in planes parallel to each other, perpendicular to the spring axis, but inclined with respect to the plane of extension of the propeller, it is say, to the planes in which the other turns of the spring. This different inclination actually causes a unsatisfactory distribution of the load on the spring and the It makes more sensitive to wear.

In the present case, this wear effect is noticeably reduced and even eliminated almost completely due to the presence of the openings between turns together with the reduction of the diameter of said extreme turns (105) compared to the immediately adjacent turns. As you can see by Figures 4A and 4B, the characteristics of this spring, presence of openings between the turns and diameter difference between said Extreme turns are such that they ensure during compression of said spring, the absence of interference between the turns at along the entire operating section (see figure 4B); how consequently the spring turns will tend not to wear out, the spring will tend to work in the most similar way to the Initial configuration and its useful life will improve markedly.

Advantageously, inserting the elements thermoplastic hairpieces (412) and (422) inside the enclosure (402), the metallic contact between the spring (5) and the walls of the plate opposite the seat (2) and / or the shutter (4) is removed further.

The valve designed in this way is capable of so much, on the one hand, to ensure, even at high frequencies, precise operation and, on the other hand, the half-life of elements of elastic effort and, therefore, of one's own valve, extend considerably.

Claims (6)

1. Valve for alternative compressors, comprising a seat (1) provided with at least one flow path (111), a sealing element (4) capable of obstructing said flow path (111) and movable with respect to said seat in a certain direction, and means (5) for elastically forcing said shutter (4), which are capable of forcing said shutter (4) to occupy a certain position and which are active in the direction of movement thereof; said elastic antagonist means (5) comprising at least one cylindrical helical compression spring (5), characterized by the presence, between all the turns and along the entire working length of the spring (5), both in resting conditions and under compression conditions, of openings between turns and, simultaneously, characterized in that the extreme turns (105) have a smaller diameter than that of the immediately adjacent turns (205), and by a conicity variation ratio of both extreme turns, according to which the difference in diameter between the extreme turns (105) and the immediately adjacent turns (205) is in the range of at least one and a half times the section of the metal wire constituting said spring. 2. Valve according to claim 1, wherein the difference in diameter between the extreme turns (105) and the turns (205) immediately adjacent to them is twice the cross section of the metal wire forming said spring. 3. Valve, according to any of the claims 1 and 2, wherein said conical end turns They are rectified. 4. Valve, according to any of the claims 1 to 3, wherein the passage of said springs is variable. 5. Valve, according to any of the claims 1 to 4, wherein said antagonist means elastics (5) are arranged inside a wrapping body (402) which is properly disposed with respect to said element shutter (4). 6. Valve, according to any of the claims 1 to 5, wherein the protective elements (412, 422), preferably made of plastic material, are arranged inside the body that receives the spring.