MXPA99003964A - Compressor provided with an improved piston - Google Patents

Abstract

Electric compressor comprising a piston provided with a respective head and a valve plate mounted between said head and the body of the cylinder and provided with a gas suction port, said head being provided with a protrusion adapted to be intermittently introduced in said suction port substantially in the top dead-center position of the piston. Said piston is provided externally, in the portion thereof which is opposite to the head side, with a recess that is accessible from the outside and is orientated towards the inner volume of said piston, said recess penetrating the body of said piston down to a depth which is at least equal to the height of said protrusion above the plane of said head.

Description

COMPRESSOR WITH IMPROVED PISTON DESCRIPTION OF THE INVENTION The present invention relates to a particular embodiment of a reciprocating piston of alternating movement in a respective cylinder. In order to illustrate more effectively and illustrate the invention more clearly, the assumption is made that the piston works in close association with a compressor for refrigerators, in particular in electrical appliances of the household type, without this limiting the scope of the invention solely to such application or connection. For a long time the fact has been known, in view of the improvement of the efficiency - thermodynamics of the compressors, which is absolutely necessary for the volume of the discharge orifice, which is not affected by the displacement of the piston, so that it is =? as small as possible. The reasons for such a requirement are well known to those of ordinary skill in the art, so that they will not be mentioned here again In view of the artificial reduction of such a volume, the practice is known in the art, for example from the description in US 5,149,254 to provide, in the head of the related piston, a projection (post 54) which is placed and dimensioned in a way that allows the projection to penetrate almost completely into the discharge hole when the piston reaches its top dead center, -without "that, of course, this gives rise to any interference ~ with other nearby parts. that the volume of the discharge orifice can be occupied by the gas that will be temporarily reduced in an ingenious manner, but it will be a very considerable extension, so that the total efficiency of the compressor can actually be significantly enhanced, as has already been done. The above solution is certainly simple, reliable, economical and safe, however, in the course of highly automated production of this class of pistons, many practical disadvantages tend to arise, as described below. detail. The grinding operation on the outer cylinder of the compressor pistons is carried out by means of a grinding technique without a fixed and secured center of rotation; The same process is generally used to produce millions of cylindrical parts such as cylindrical rollers or roller bearings. The grinding process consists essentially of a continuous sequence of such pistons transported by a means of transportation through a plurality of wheels of grinding or a similar means that is subjected to abrasion by the action of the plurality of grinding wheels or similar means. The size, orientation and amount of the grinding means are such that it allows the pistons transported within such processing step to be sent here in sequence with their axes coincident with, and parallel to the direction of movement thereof, through the plurality of grinding media. However, if the pistons are to be placed in contact between, yes, in the sense that the head of one of said pistons is in contact with the trailing edge of the neighboring piston, then serious drawbacks arise in that, due to the The aforementioned projection, the pistons tend to assume a position which is slightly inclined with respect to the direction of movement. The result is that they are placed obliquely at the front or with respect to the grinding means and, therefore, practically prevent the grinding process from being carried out. In order to eliminate such a drawback, the pistons are therefore separated from each other in such a way that the projection thereof is prevented from coming into contact with any other piston. Such a very simple and effective measure of separation of the pistons from each other, however, has the effect of slowing down and, therefore, decreasing the productivity of the grinding operation, since the pistons must be placed in cadence in a process at a much lower speed, due to the need to maintain its forward speed without alteration, while the "virtual" length of it, that is, the length that includes both the actual length of the piston as the intermediate space that separates it from the subsequent piston in the sequence, on the contrary it increases, and this is better illustrated in the attached figure 1. Therefore, it would be desirable and indeed it is the primary purpose of the present invention to provide a technical solution which, when applied to such a compressor piston, eliminates the above described drawback in a simple, inexpensive and reliable manner. In addition, such an objective must be achieved through the use of techniques and materials that are simple and easily available in the market, while at the same time avoiding affecting the operating capabilities and the total reliability of the related compressor in any measure. According to the present invention, such objectives are achieved in a piston of the kind described below by means of a non-limiting example with reference to the accompanying drawings, in which: Figure 1 is a symbolic representation of a plant of Piston grinding according to the technology of the state of the art; Figure 2 is a symbolic representation of the same "piston grinding plant according to the present invention; Figure 3 is a view from the opposite side of the head of a piston according to the present invention; is a view in longitudinal section of the same piston illustrated in Figure 3, Figure 5 is a view from the head of the piston itself, Figure S is a sectional view of two pistons according to the present invention, in which the The head of one of them is in contact with the lower portion of the other, Figure 7 is a perspective view, partially in cross section of a variant of a piston according to the present invention, together with the connecting rod associated with the piston. With reference to Figure 1, it can be noted that the grinding process can be carried out currently by using at least two wheels, i.e., an adjustment wheel 1 and a wheel 2. of real grinding. Between the wheels, which rotate on parallel axes, a plurality of pistons 3 are caused to pass in a sequence, preferably transported through it on a band 4 or any other equivalent transport and support means.

In order to prevent the projection of each piston head from interfering with the adjacent piston as mentioned above, each piston is separated from the next one by a separation interval 5 obtained through an appropriate means for establishing cadence and separation 6 which is well known in the art. It can easily be seen that, if in this case the speed of forward movement of the pistons is 700 mm / min, the length of pistons of 23 mm and-the distance of each piston from the next is 25 mm, then the output rate of the piston will constitute: 700 / (23 + 25) x 60 = 875 pistons / hour However, if the pistons must be sent to a rectification operation without any separation provided between them and therefore, in close contact with each other, as symbolically illustrated in Figure 2, then all other conditions remain unaltered, and the Piston production speed would constitute: 700/23 x 60 = 1826 pistons / hour that is, a production per hour that is much greater than the double value that can be obtained with the technology of the prior art is obtained in this way. - According to the invention, the possibility of feeding the pistons for grinding with the head of each piston in close contact with the lower part of the adjacent piston, wherein each piston head is provided with the projection described above, is obtained by providing each piston with a substantially cylindrical recess 7 on the side of the piston which is placed at the head 8 thereof, as best illustrated in Figure 4, so as to make it possible, when placing the pistons one against another and oriented in the same direction, that the projection on the head of a piston enters freely, without any restriction and in any angular position of the same pistons, the recess of the adjacent piston, so that it is obtained that such protuberances do not interfere with the adjacent pistons, which therefore can maintain the same axis, and at the same time, remain in close contact with each other. For this purpose, the recess must have the following characteristics: firstly, it must extend inside the piston body by a depth at least equal to the height of the projection 9 from the level of the head 8; furthermore, the recess must be capable of accommodating the adjacent piston projection, as illustrated in Figure 6, regardless of the position in which the pistons can be found in themselves. in relation to each other in the direction of rotation with respect to the common axis 10. This practically not only allows the pistons to be supplied in the grinding line regardless of the actual angular position or the orientation of the same, - but also makes possible that each piston is completely free to rotate during grinding and transport, independently of the two pistons, one that precedes it and another that follows it. Such a link can be obtained with a recess 7 which provides, towards the outer cylindrical surface of the piston, a circular edge 12 that does not have a thickness - greater than the minimum distance between the projection 9 projecting from the piston head and the edge 13 circular of the same head. Given such restrictions, it can be readily appreciated that such recesses will preferably have a cylindrical shape. However, such recesses may also be provided in any other appropriate manner, provided that they allow the basic requirement placed in the same recess to be met, that is, the capacity thereof to fully accommodate the projection therein. With particular reference to Figure 7, it should be noted that the invention is fully applicable, provided that the provisions due as described above are made, also to pistons provided with a piston stump that is manufactured integral with the rod respective connection, and free of any through hole provided to accommodate such a piston stump. In such a case, the recess must be located in the front of a cavity 20 provided within the piston body 21 and adapted to accommodate the piston pin 22 integrally manufactured with the head 23 of the respective connecting rod 24.

Claims (5)

1. An electric compressor, comprising a cylinder body, a piston provided with a respective head, a valve plate positioned between the head and the cylinder body and provided with an air suction hole, the head is provided with a projection eccentr_ca_ able to be intermittently inserted into the hole, characterized in that the piston is provided, in the portion thereof which is opposite the head side, with a recess that is accessible from the outside and that is oriented towards the interior volume of the piston .

2. The electric compressor according to claim 1, characterized in that the recess extends in the body of the piston downwards a depth that is at least equal to the height of the projection above the plane of the head.

3. The electric compressor according to claim 2, characterized in that the recess has a substantially cylindrical foxma having its axis coinciding with the axis of the piston, the recess is additionally delimited externally by a circular edge that constitutes the terminal portion of the surface cylindrical piston opposite the head, the thickness of the circular edge is not greater than the minimum distance between the projection projecting from the head and the circular edge of the head itself.

4. The electric compressor according to any of the preceding claims, characterized in that the recess is manufactured integrally with the piston.

5. The electric compressor according to the preamble of claim 1, characterized in that the piston is further adapted to accommodate at least one piston stump that can possibly be provided integrally with the respective connecting rod, characterized in that the piston is not provides with some through hole for accommodating the piston stump and the piston is provided with a cylindrical recess that is positioned in front of a cavity provided within the piston body and adapted to at least partially accommodate the piston stump along with the piston. head of the connecting rod. EXTRACT OF THE INVENTION An electric compressor comprising a piston provided with a respective head and a valve plate mounted between the head and the cylinder body and provided with a gas suction port is provided, the head is provided with a projection adapted for The piston is provided externally, in the portion thereof which is opposite the side of the head, with a recess that is "accessible from the outside and that is oriented towards the interior volume of the piston, the recess penetrates the piston body down to a depth which is at least equal to the height_ of the projection above the plane of the head.