KR20150117665A - Improvement in a piston for a refrigeration compressor - Google Patents

Abstract

The piston P of the present invention comprises a tubular skirt 10 and a head 12 attached to the inside of the skirt 10 and close to the end edge 11 of the skirt 10 and carrying a suction valve 20 H). The head H includes a central hub 30 having an end front surface 30a and an end edge 31a incorporating radial wings 31 attached to the skirt 10. [ The central hub 30 defines a respective suction axis passage 32 with a skirt 10 and a radial wing 31. The head H also has a front surface 40a and a rear surface 30a which is attached to the center hub 30 by an end front surface 30a of the center hub 30, Wherein the outline of the cover 40 is the inner contour of the skirt 10 and the suction annular opening 42 closed by the suction valve 20 Lt; RTI ID = 0.0 > a < / RTI >

Description

[0001] IMPROVEMENT IN A PISTON FOR A REFRIGERATION COMPRESSOR FOR A FREEZE COMPRESSOR [0002]

The present invention relates to a type which is used in a compressor of refrigeration systems and which provides an integrated head part inside one of the ends of a tubular cylindrical skirt part to be axially displaced from the inside of the compression chamber in the cylinder of the cylindrical crankcase of the compressor To an improved piston.

In a reciprocating compressor driven by a linear motor, gas suction and compression operations are performed by a reciprocating axial movement of the piston in the interior of the closed hill cylinder by the head and in some configurations assembled inside the hermetic housing of the compressor . The piston is driven by the motor unit of the compressor.

Pistons for refrigeration compressors typically exhibit a monolithic configuration that defines the formation of a head portion and a skirt portion of one piece, and such a piston configuration may include, for example, a metal stock from a normal steel By machining of the substrate. This manufacturing process is costly and leads to a lot of material waste.

Further, other methods of obtaining a single-piece piston, such as cold forming, stamping, and the like, are known. However, such a method affects the operation of the piston in the compressor due to its high level of dimensional uncertainty as well as high manufacturing costs.

These defects are more severe in configurations where suction is provided through the body of the piston.

In addition to the above drawbacks, the monolithic configurations for the freezing pistons, in addition to the minimal cost of materials and fabrication, operate in compressors of the type predominantly associated with long pistons, more particularly of the oil lubrication type, or with gas bearings It is not permissible to construct a piston which is associated with a piston, but which presents the possibility of simultaneously providing a piston which is light but without loss of quality resistance, low porosity, low coefficient of friction, and the like.

The patent application PCT2008 / 000192 (WO2009 / 003260) of the same assignee of the present application discloses a method of forming a hollow cylindrical body which is closed by a head formed in an independent piece, preferably near the end edge of the skirt, And a tubular skirt.

In this conventional arrangement, the piston is formed of two different parts defined by the skirt and the head, in which case the head has a front face which is flush with the plane normally containing the end edges of the skirt, The suction openings selectively closed by the suction valve carried by the suction valve are provided.

The head is formed by a central hub, which is usually tubular and cylindrical, which incorporates a radial wing in which the end edges are abutted against the skirt in the interior of the skirt. Thus, the contour of the central hub remains radially spaced from the skirt, defining the respective suction openings between the radial wings, and the front surface of the head is defined by the leading edge of the center hub.

In the particular configuration of the prior art, the piston head also incorporates a cylindrical peripheral ring that is integrated into one piece at the end edges of the radial wings, and is preferably placed and attached within the skirt by interference .

In the prior art solution, the piston head defines a support surface for the intake valve, as well as a structural part for securing it to the skirt, through its front face, Lt; RTI ID = 0.0 > radial < / RTI > gap.

Although the prior art solution in which the skirt and head are formed in one piece is constructive and advantageous in terms of older configurations, it is still possible to reduce the restrictions on the shape caused by the formation of one piece of head , It presents the drawback of requiring more complex and costly manufacturing processes. The complexity, cost, and shape constraints mentioned above are even more important when the head is placed against a skirt in one piece and further integrates the peripheral ring to be attached. In such a case, the complexity of the shape constraints and fabrication processes tends to create an annular gap with excessive radial dimension between the central hub and the peripheral rings of the head, resulting in a high The use of suction valves with greater thickness and mass to minimize the risk of fatigue, mainly due to the flexion degree that the suction valves undergo in the annular gap in the presence of pressure differentials .

In addition to the above drawbacks, the one-piece piston head configuration does not allow it to be formed with different materials.

It is therefore an object of the present invention to provide a method of manufacturing a piston head which permits easy fabrication at a relatively reduced cost to form a piston head and which is less restrictive in shape and which can be applied to the type of piston contemplated herein And the like.

Yet another object of the present invention is to provide an improvement in the piston which allows to construct a long piston from different materials in the formation of the head using different fabrication processes as well as between the skirt and the head, The materials being defined as a function of the demands of each particular part of the piston during operation of the piston in the compressor.

Yet another object is to provide a piston that permits suction to be obtained through the interior of the piston itself, in an easy and reliable manner.

These and other objects are achieved through improvements in the piston for a refrigeration compressor, the piston comprising a tubular skirt which is generally cylindrical and a head which is attached to the inside of the skirt, close to the end edge of the skirt and carrying a suction valve do.

According to one improvement of the invention, the piston head is formed by a central hub and a cover, which has a reduced contour as compared to the contour of the skirt and has an end front, and which, from the inside to the skirt, Incorporating radial wings to which the edges attach, the central hub defining respective suction axial passages between the contour of the central hub and the skirt and between the radial wings,

The cover is defined by a plate having the same outline as the inner contour of the skirt and having a rear surface and a front surface attached to the central hub by the end front surface of the central hub, the contour of the cover having an inner contour of the skirt, Lt; RTI ID = 0.0 > a < / RTI > closed annular opening.

The improved structural solution of the present invention uses a skirt formed by a tube extension and a piston head formed of two pieces defined by a central hub and a cover which are separated and have a less complicated configuration In the configuration with the end edges of the radial wing incorporating the peripheral ring circumferential extension, which is radially placed against and attached to the skirt, in particular from the inside of the skirt, into one piece, Can be made with materials that are different than those needed to make the heads and through relatively simple and less expensive processes.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described below with reference to the drawings attached hereto.
Figure 1 is an exploded perspective view and partial cut-away view schematically showing a first piston arrangement for a refrigeration compressor, in which a screw for attaching a tubular skirt, a central hub, a cover, a suction valve, Fig.
Fig. 2 schematically shows a front plan view of the piston arrangement illustrated in Fig. 1, showing a case in which it is assembled but without a suction valve; Fig.
Figure 3 schematically shows a cross-sectional view of the piston illustrated in Figures 1 and 2, where the cutting is done along line III-III in Figure 2, but also illustrating the suction valve in its operative position and inoperative position drawing.
Figure 4 is an exploded perspective view and partial cut-away view schematically showing a second piston arrangement for a refrigeration compressor, comprising a tubular skirt, a central hub for carrying peripheral rings, a cover, a suction valve, Fig.
Fig. 5 schematically shows a front plan view of the piston arrangement illustrated in Fig. 4, showing a case in which it is assembled but without a suction valve; Fig.
Fig. 6 schematically shows a cross-sectional view of the piston shown in Figs. 4 and 5, wherein the cutting is effected along the line VI-VI of Fig. 5, but also illustrates a suction valve drawing.
7 is a perspective view of an alternative configuration example of a bulky center hub;
8 is a perspective view of a cover to be retrofitted to the central hub;
9 is a schematic cross-sectional view of a set of cover-center hubs in an assembled state;
Figures 10 and 11 are schematic cross-sectional views of a set of cover-center hubs made in accordance with two alternative configuration alternatives and in an assembled condition;
12 is a perspective view of another alternative configuration example of a center hub provided with a through hole;
13 is a perspective view of a cover to be retrofitted to the central hub;
Figure 14 is a schematic cross-sectional view of a central hub set and cover in an assembled state;

The following is a description of a piston of the type in which the present invention was used to pump refrigeration gas in a refrigeration compressor.

Refrigeration compressors usually have a closed end by a valve plate (both not shown) and include a cylinder defining a compression chamber with a cylinder. The cylinder also has an opposite end, through which the piston is assembled, which piston reciprocates inside the cylinder during the compression cycle and the suction cycle of the coolant fluid during operation of the compressor, Is obtained by operation of a motor unit (not shown) operably coupled.

In some compression compressor configurations, such as those illustrated and described below, suction of coolant fluid occurs through the piston, which is equipped with a suction valve. In the case of these configurations in which suction occurs via the piston, the head of the piston described below has at least one suction opening selectively closed by a respective suction valve carried by the head of such a piston.

The present invention provides a configuration for a piston (P) in which the piston (P) is closed by an end edge (11), which is often formed by a head (H) as a separate piece from the skirt (10) Shaped skirt 1 attached to the inside of the skirt 10 next to the end edge 11 by suitable fastening means such as mechanical interference or the like. The head H carries at least one suction valve 20 illustrated at least in FIGS. 1 and 3.

The skirt 10 is defined by respective steel tube extensions preferably having an external hardening surface treatment and is configured to abut the end edge 11 and fix the head H, Which provides an inner end region 10a inside the axial projection of the outer contour of the skirt 10. [

According to the invention, the head H is formed by a central hub 30 which is suitable for the operating state of the piston and which is usually obtained from a metal alloy already known in the relevant field, And incorporates a radial wing 31 with an end face 30a inside the inner end region 10a where the end edges 31a are fixed in the skirt 10 into a single piece . The central hub defines a respective suction axial passage 32 between its outline and the skirt 10, and between the radial wings 31.

The head H is also defined by a plate made of a metal alloy similar to or different from that used to form the central hub 30 and usually represents a circular contour with the same center as the inner contour of the skirt 10, Has a front face 40a and a back face 40b which are fixed to the central hub 30 by the end front face 30a of the skirt 10. In this case the outline of the cover 40, Maintains a radial clearance R defining a suction annular opening 42 that is fluidly communicated with axial passages 32 and is selectively closed by a suction valve 20. [

As can be observed in the figures, a plenum is formed to accumulate the refrigerating gas supplied to the suction annular opening 42 whenever the opening of the intake valve 20 occurs in the upper flow of the first one The suction annular opening 42 is maintained to be axially spaced apart from the suction axial passage 32. This arrangement minimizes the load losses in supplying refrigeration gas to the interior of the compression chamber.

The assembly of the head H inside the skirt 10 is performed so that the front surface 40a of the cover 40 is flush with the plane containing the end edge 11 of the skirt 10. [ This configuration generally includes a suction valve 20 in the form of an annular blade having a middle diameter portion for securing to the front face 40a of the cover 40 and the suction annular opening 42 While allowing it to rest against the end edge 11 of the skirt 10 when it is in its non-operating state of closing. Normally the suction valve 20 passes through the intermediate diameter portion of the suction valve 20 and is guided by the threaded central screw 25 in each threaded hole 41 provided in the cover 40 to the head H, Respectively.

In the embodiment illustrated in Figures 1-3, the end edge 31a of each radial wing 31 is defined by a recess 12 (FIG. 12) provided inside the skirt 10 at the inner end region 10a of the skirt 10, And is open to the end edge 11 of the skirt 10. The recess 12 may occupy only a circumferential extension of the inner contour of the skirt 10 sufficient to accommodate each radial wing 31 and the recess 12 may be formed in relation to the inner contour And defines respective steps axially rearwardly spaced about the end edge 11 of the skirt 10. However, as illustrated, usually a single recess 12 is provided, the recess 12 being continuous and occupying the entire internal circumferential contour of the skirt 10.

It should be appreciated that fixing the center hub 30 to the inside of the skirt 10 can be done without having to provide the recess 12.

Due to the fact that the components of the skirt 10, the central hub 30 and the cover 40 are independent of each other, each of these components is obtained from a particular process and from materials more suited to the function to be exerted by each of the components Can be.

It should also be understood that the solution of the present invention also contemplates the possibility of using the same process for obtaining the parts comprising the piston and the same material for obtaining the parts in the present invention, no.

It should be appreciated that the cover 40 may be attached to the central hub 30 by any other suitable means, such as welding, bonding, mechanical interference with or without threading.

4-14, the end edges 31a of the radial wings 31 are placed radially against the skirt 10 from the inside of the skirt 10 as a single piece, The ring circumferential extension 35 is integrated.

The peripheral ring circumferential extension 35 is provided on the inside of the skirt 10 in the region of the end edge 11 of the skirt 10 and the skirt 10 is provided in the region of the end edge 11 of the skirt 10, Which preferably occupies each circumferential extension of the inner contour of the skirt 10 and which is open to the end edge 11 of the skirt 10, In order to define an annular step spaced axially backward relative to said end edge 11 of said end portion.

Thus, although not illustrated herein, each radial wing 31 is provided with opposite circumferential extensions 35 that are spaced apart from the other circumferential ring circumferential extensions 35 incorporated in each of the other radial wings 31 It is to be understood that the radial wing 31 can have an end edge 31a that integrates the peripheral ring circumferential extension 35 extending to both sides of the radial wing 31. [

In a configuration that incorporates the peripheral ring circumferential extensions 35, suction axial passages 32 are defined between the central hub 30 and the peripheral ring circumferential extensions or extensions 35. In the arrangements illustrated in Figs. 4-14, the end edges 31a of the radial wing 31 are joined by one peripheral ring circumferential extension 35.

Due to the fact that the components of the skirt 10, the central hub 30 and the cover 40 are separate from each other, they can exhibit simpler fabrication shapes, Direction expansion portion 35 is integrated.

The configuration of the central hub 30 separated from the cover 40 is such that the distance between the cover 40 and the skirt 10 is less than the distance between the cover 40 and the skirt 10 without the manufacturing processes of the central hub 30 and negative consequences for shape simplicity. It is possible to obtain an annular gap having suitable radial dimensions and thereby to avoid the risk of breakage from the fatigue caused by the level of flexure received in said annular clearance, especially in the presence of a high pressure difference between suction and discharge of the compressor And a lower mass of intake valve 50 is used.

The circumferential ring circumferential extension 35 represents an axial height equal to the height of the radial wings 31 regardless of whether one or more circumferential ring circumferential extensions 35 are provided, In the same plane.

As can be observed, regardless of the alternative configuration applied to the piston P, the radial wings 31 are formed so as to remain axially spaced backward and are spaced apart from the rear surface 40b of the cover 40 The aforementioned axial spacing is allowed between the suction axial passages 32 formed between the central hub 30 and the skirt 10 and the suction between the cover 40 and the skirt 10 An annular opening 42 is formed.

1 to 11, the axial spacing between the cover 40 and the radial wings 31 is greater than the axial spacing between the radial wings 31 and the radial wings 31, axially spaced back and away from the end front 30a of the center hub 30. [ 31).

1 to 6, the central hub 30 has an axial through-hole 33 in its end front surface 30a, and the cover 40 has a through- When the rear face 40b of the cover 40 is brought into contact with the end front face 30a of the center hub 30 to fix the cover 40 to the center hub 30 at the central hub 30b, And the central axial pin 43, which is fitted and fitted in the axial through hole 33 of the shaft.

The central hub provided with the through-hole connects the piston to the connecting rod and is advantageous when such a connecting rod is connected to the motor. This through hole can be used to fix the connecting rod. An advantage of the hole and pin fitting concept is that the center obtained in the assembly of the two components is of the same concentricity and this results in more bonding processes (brazing and gluing) .

7 to 9, the central hub 30 can be bulky and can incorporate a central axial pin 34 at its end front surface 30a, A central axial hole 44 is also provided on the rear face 40b of the cover 40 and optionally on the front face 40a of the cover 40 in which the cover 40 is secured to the central hub 30 The central axial pin 34 is fitted and attached when the rear face 40b of the cover 40 is placed against the end front face 30a of the center hub 30. [

As in the previous embodiment, this arrangement is also intended to facilitate assembly and to achieve center-of-gravity properties. With regard to the process of obtaining the components, it is easier to obtain it without a through hole in the case of a sintered central hub. The perforated cover can be provided by a simple stamping process, which is cost-effective.

In this configuration, after the piston is mounted, machining of the screw is performed on the upper portion as illustrated in Fig. During such machining, the pins of the hub can be removed and the through holes remain in place. Removing the pins does not affect the whole because they are provided to facilitate the mounting process and the bonding process. After the soldering and bonding of the parts is done, the machining of the fin can be done to form a suction valve or a used thread.

10 is provided with a central axial hole 44 having a relatively large diameter and open on the rear face 40b of the cover 40. In this case the central hub 30 has a large volume, (36) beyond the radial wings (31) to fit and secure in the central axial bore (44) of the radial wing (40).

In this embodiment, the bonding zone where the adhesive or welding (from the solder) is present is flat, thus exposing the adhesive or weld to traction tension. However, adhesives are more resistant to shear forces, which is done through a hub that defines its own fitting. Fabrication of the hub by sintering can be made easier if the pin is not present.

In the configuration being described, the suction valve 20 is attached to the head H of the piston P, as described above, i.e. by providing a threaded hole machined after assembly.

Figure 11 illustrates a structural form for the head H with the backside 40b where the cover 40 is placed against and adhered to the end face 30a of the center hub 30 by welding or gluing.

In such a configuration, the fitting guide / pin between the cover and the center hub is removed, and the cover can be manufactured in a simpler manner, resulting in cost reduction. However, the assembly can be damaged to some extent, because it lacks a way to center the cover about the central hub.

As described above, the suction valve 20 is attached to the head H of the piston P by providing a threaded hole machined after assembly.

In the embodiment illustrated in Figures 12-14, the radial wings 31 have an axial height that is the same as the axial height of the central hub 30. In this case, the central hub 30 has a larger diameter and an axial through-hole 33 open to its end front surface 30a. The cover 40 has a base portion 43a having a larger contour than the contour of the axial through hole 33 and an axial through hole 33 of the central hub 30 on its rear surface 40b. Which incorporates a central axial pin 43 that includes an assembly portion 43b that fits and adheres to and is smaller in profile than the end surface 30a of the center hub 30 for attaching the cover 40. [ When the base portion 43a is placed. In this configuration, the axial height of the base portion 43a of the central axial pin 43 defines the axial spacing between the suction axial passage 32 and the suction annular opening 42.

This configuration has the advantage that instead of stamping, it is possible to produce a cover with a fitting pin by cold forming. This process, which first uses a wire, results in less material waste than the stamping process. Also, the fabrication of the hub is made simpler through the sintering process, because such pieces exhibit only one height, as opposed to a hub with, for example, fitting pins that represent multiple heights in the same part.

As described above, the suction valve 20 is attached to the head H of the piston P by providing a threaded hole machined after assembly.

It is also to be understood that the structural alternatives described herein may be represented individually as particular configurations, or may be depicted as being partially or fully coupled to each other.

Claims (16)

An improved piston for a refrigeration compressor,
The piston P has a tubular skirt 10 and a head H which is attached from the inside of the skirt 10 and is close to the end edge 11 of the skirt 10 and carries the suction valve 20 , Wherein the improved piston
The head H is formed by a central hub 30 and a cover 40 which has a reduced contour as compared to the contour of the skirt 10 and which has an end front 30a, Which integrates the radial wings 31 to which the end edge 31a is attached in the skirt 10 from the inside of the skirt 10 to the skirt 10 and the center hub 30, 10) and between the radial wings (3), each suction axial passage (32)
The cover 40 has the same outline as the inner contour of the skirt 10 and has a rear surface 40b attached to the center hub 30 by the end surface 30a of the center hub 30, Wherein the profile of the cover (40) defines a radial gap defining a suction annular opening selectively closed by the suction valve (20) with respect to an inner contour of the skirt (10) Wherein said piston comprises a piston. The method according to claim 1,
Characterized in that the front face (40a) of the cover (40) is flush with the plane of the end edge (11) of the skirt (10). 3. The method according to claim 1 or 2,
An end edge 11 of each of the radial wings 31 is provided on the inside of the skirt 10 in the inner end region 10a of the skirt 10 and in the recess 12 open to the end edge 11 Wherein said piston is fitted and attached. The method of claim 3,
The recess 12 defines an inner contour of the skirt 10 defining respective steps axially spaced back relative to the end edge 11 of the skirt 10 relative to the inner contour. And wherein the piston extends in the circumferential direction. 5. The method of claim 4,
And a continuous single recess (12) occupying the inner circumferential contour of the skirt (10). 3. The method according to claim 1 or 2,
The end edges 31a of the radial wings 31 are integrally joined to the skirt 10 in a single piece by circumferentially circumferentially extending portions 35 that are radially placed against and attached to the skirt 10 from the inside of the skirt 10. [ Wherein said piston comprises a piston. The method according to claim 6,
The peripheral ring circumferential extension 35 is provided on the inside of the skirt 10 in the region of the end edge 11 of the skirt 10 and is open to the end edge 11 of the skirt 10 Each of the circumferential extensions of the inner contour of the skirt 10 to define an annular step spaced back axially about the end edge 11 of the skirt 10 with respect to the inner contour Is fitted and attached to the recess (12) that occupies the piston (12). 8. The method of claim 7,
Characterized in that the end edge (31a) of the radial wing (31) is engaged by a single peripheral ring circumferential extension (35). 9. The method according to claim 7 or 8,
The peripheral ring circumferential extension 35 represents an axial height equal to the axial height of the radial wings 31 and the circumferential ring circumferential extension 35 is on the same plane as the radial wings 31 Wherein the piston comprises a piston. 10. The method according to any one of claims 1 to 9,
Characterized in that the radial wings (31) are spaced apart and axially back from the rear face (40b) of the cover (40). 11. The method of claim 10,
Characterized in that the radial wings (31) are spaced apart and axially backward from the end front (30a) of the central hub (30). 12. The method of claim 11,
The central hub 30 provides an axial through hole 33 in the end front surface 30a of the central hub 30 and is used to secure the cover 40 to the central hub 30, When the rear surface 40b of the cover 40 is laid on the rear surface 40b of the cover 40 so as to abut the end surface 30a of the center hub 30, (43) which is fitted in and attached to the axial through hole (33) of the piston (30). 12. The method of claim 11,
The center hub 30 is bulky and incorporates a central axial pin 34 at an end front surface 30a of the center hub 30. The cover 40 has a rear surface When the rear face 40b of the cover 40 is brought into contact with the end front face 30a of the center hub 30 so as to fix the cover 40 to the center hub 30, Characterized in that a central axial hole (44) is provided in which the central axial pin (34) is fitted and attached. 11. The method of claim 10,
Characterized in that the radial wing (31) has the same axial extension as that of the central hub (30) and is in the same plane. 15. The method of claim 14,
The center hub 30 provides an axial through hole 33 in the end front surface 30a of the center hub 30 and the cover 40 extends from the rear surface 40b of the cover 40 And includes a base portion 43a having a contour larger than the contour of the axial through hole 33 and a mounting portion 43b having a smaller contour and fixing the cover 40 to the central hub 30 A central axial pin 43 that fits and attaches to the axial through hole 33 of the central hub 30 when the base portion 43a is placed against the entire front end of the central hub 30 for a predetermined distance To the piston. 15. The method of claim 14,
The cover 40 is provided with a central axial hole 44 which is open to the rear face 40b of the cover 40. The central hub 30 is bulky, Has an end portion (36) projecting axially beyond the radial wing (31), fitted and attached to the directional hole (44).

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