CN100434698C - Refrigeration Compressors - Google Patents

Abstract

A refrigeration compressor having a hermetically sealed compressor housing, a piston-cylinder unit that compresses refrigerant works in the compressor housing, and includes a suction valve with a suction port arranged at the piston-cylinder unit In the valve plate, a suction muffler with an injection volume is arranged on the cylinder head of the piston-cylinder unit. The refrigerant flows through the suction muffler to the suction valve of the piston-cylinder unit. The suction muffler has an inlet cross-section, and the refrigerant passes through the inlet cross-section. The section flows into the suction muffler and a compensating volume communicating with the interior of the suction muffler and the compressor housing is provided, in which the refrigerant fluctuates. It is provided that the inlet cross-section is at the same time the connection between the compensating volume and the filling volume, the compensating volume being formed by a sleeve which seals around the suction or the inlet cross-section and surrounds the refrigerant suction line at least along one section and points towards the compressor The casing and the suction pipe are connected with the evaporator of the refrigeration compressor, and extend into the interior of the compressor casing.

Description

Refrigeration Compressors

technical field

The present invention relates to a hermetically sealed refrigerating compressor having a hermetically sealed compressor housing in which a piston-cylinder unit compressing refrigerant operates, in which said piston- The cylinder head of the cylinder unit is provided with a suction muffler through which the refrigerant flows into the suction valve of the piston-cylinder unit.

Background technique

Such refrigeration compressors have been known for a long time and are mainly used in refrigerators and freezers. Therefore, the annual production volume is high.

Although the power consumption of a single refrigeration compressor is only approximately between 50 and 150 watts, when considering all the refrigeration compressors used in the world, it produces high power consumption. Due to the rapid development of underdeveloped countries, Power consumption continues to increase.

Therefore, any technological improvements made to refrigeration compressors and increased efficiency offer great potential for energy savings when extended to refrigeration compressors used throughout the world.

Refrigeration processes like this have long been known. The refrigerant is heated in the evaporator by absorbing the energy in the space to be cooled, and finally the refrigerant is superheated and pumped to a higher pressure stage by means of a refrigeration compressor, where the refrigerant rejects heat through the condenser and passes through The throttle valve feeds back to the evaporator, where the refrigerant pressure is reduced and cooled.

The greatest and most important potential for possible improvement in efficiency is to lower the temperature of the refrigerant at the beginning of its compression process. Every reduction in the suction temperature of the refrigerant entering the cylinders of the piston-cylinder unit leads to a reduction in the technical work required for the compression process, as does the reduction in temperature during the compression process and the discharge temperature associated therewith.

In the known hermetically sealed refrigerant compressors, depending on the design, the refrigerant undergoes an intense heating on its way from the compressor (cooling space) to the suction valve of the piston-cylinder unit.

During the suction stroke of the piston-cylinder unit, the suction of the refrigerant takes place through the suction line coming directly from the compressor. In known hermetically sealed refrigeration compressors, the suction pipe usually leads into the hermetically sealed compressor housing, mostly into the vicinity of the inlet cross-section of the suction muffler, from which the refrigerant flows into the The suction muffler, and from said suction muffler flows directly into the suction valve of the piston-cylinder unit. Suction mufflers are primarily used to keep the noise level of the refrigeration compressor as low as possible during the suction process. Known suction mufflers generally comprise several volumes communicating with one another, a suction cross-section and an opening through which refrigerant is drawn from the hermetically sealed compressor housing volume into the interior of the suction muffler , and said opening is tightly abutted close to the suction valve of the piston-cylinder unit.

During the entry of the refrigerant between the inlet of the compressor housing and the suction valve of the piston-cylinder unit, undesired heating of the refrigerant takes place as described above. Measurements show that at a refrigerant temperature of 32°C in the suction line (predetermined by standardized ASHRAE conditions), the refrigerant has heated to approximately 54°C in the first suction muffler volume shortly before entering the compressor housing. The main reason for this unwanted heating of the refrigerant is actually the mixing of the refrigerant newly flowing into the compressor housing from the suction pipe with the warmer refrigerant already located in the compressor housing. In principle, the mixture is produced in such a way that the suction valve of the piston-cylinder unit is only opened in the crank angle range of approximately 180°, and thus the refrigerant is only sucked into the cylinder of the refrigeration compressor within this time window. Thereafter the suction valve is closed during the compression cycle. Even when the suction valve is closed, the cold refrigerant has an almost constant mass flow, whereby the refrigerant flows into the compressor housing from behind and stays there, cooling the moving piston-cylinder unit and its components, which again cause heating of the refrigerant. Due to pressure fluctuations during the compression process, there are other flow processes from the compressor housing to the suction muffler or vice versa, thus additional mixing is achieved.

In order to prevent the hot refrigerant inside the compressor housing from mixing with the fresh refrigerant coming out of the evaporator, in known refrigeration compressors the outlet of the refrigerant suction pipe is placed close to the inlet cross-section of the suction muffler. This ensures that a relatively small amount of cold refrigerant can escape from the evaporator to the interior of the compressor housing. Therefore, the suction pipe end is shaped such that an intermediate tube can be inserted into the suction pipe end. At the same time, the intermediate pipe is surrounded by a helical spring which bears on the one hand on the entry of the suction pipe into the housing and on the other hand on the intermediate pipe in order to realize the coupling of the suction pipe to the suction muffler. All these known attempts to prevent the mixing of the cold refrigerant in the evaporator with the heated refrigerant in the compressor housing only result in a reduction of this mixing, but not complete prevention.

It is known from WO 03/038280 to directly connect the inlet cross-section of the suction muffler to the outlet of the suction pipe, so that the refrigerant coming out of the evaporator is led directly into the suction muffler without reaching the interior of the compressor housing and not there heating. Based on the fact that the cold refrigerant has an almost constant mass flow even when the suction valve is closed and flows into the suction muffler (now via a direct connection), it is necessary to provide a compensating volume in the suction muffler in order to compensate for the continuous The pressure rise caused by the refrigerant flowing in from behind the suction pipe, and the refrigerant located in the suction muffler via the suction pipe can come out of the suction muffler and flow into the compressor housing again. During the next suction stroke, the refrigerant located in the suction muffler or flowing from the suction pipe into the suction muffler is sucked into the piston-cylinder unit through the suction valve on the one hand, , the refrigerant located inside the compressor housing is sucked into the compensation volume for pressure compensation, but not into the muffler.

The resulting flow characteristics thus lead to an increased risk of flow losses which would not occur in particular during overflow into the compensation volume if the suction line was not directly connected to the suction muffler.

In addition, as mentioned above, the refrigeration compressor disclosed in WO 03/038280 requires a sealed connection between the suction pipe and the suction muffler, which means that the assembly work is increased in order to ensure airtightness, wherein the bellows-like connecting element It must be tightly connected to the compressor housing and the suction muffler. In the event that the bellows-shaped connecting element loses its airtightness, the desired reduction in the refrigerant temperature at the start of the compression process may no longer be achieved, and the refrigeration compressor also operates with a lower efficiency. This is particularly problematic in the case where the compressor housing is not hermetically sealed, for example by welds, so that a possible failure of the sealing connection between the suction pipe and the suction muffler is not noticeable to the operator.

Contents of the invention

It is therefore an object of the present invention to avoid this disadvantage and to provide a refrigeration compressor of the type mentioned at the outset, in which the temperature of the refrigerant is kept as low as possible at the beginning of the compression process, and thus in the cylinder of the suction piston-cylinder unit , since the refrigerant coming out of the evaporator is prevented from flowing into the interior of the compressor housing, while at the same time flow losses during suction are avoided as much as possible, whereby the operational safety is improved.

This object is achieved according to the invention by the following measures.

A tight connection between the suction line and the suction muffler is therefore not required. The same result can be achieved by the construction of the invention, because the refrigeration compressor according to the invention has a hermetically sealed compressor housing, inside which a piston-cylinder unit compressing the refrigerant works, and includes Suction valve with a suction port arranged in the valve plate of the piston-cylinder unit, wherein a suction muffler with an injection volume is arranged on the cylinder head of the piston-cylinder unit, through which the refrigerant flows to the piston - the suction valve of the cylinder unit, wherein the suction muffler has an inlet cross-section through which the refrigerant flows into the suction muffler and a compensating volume is provided which communicates with the suction muffler and the interior of the compressor housing, in which the refrigerant flows fluctuations in the compensation volume described above, the inlet cross-section of the suction muffler is at the same time the connection between the compensation volume and the injection volume, and the compensation volume is formed by a sleeve which on the one hand seals around the suction or inlet cross-section and On the other hand, at least one section surrounds the refrigerant suction pipe and points to the compressor housing. The refrigerant suction pipe is connected to the evaporator of the refrigeration compressor and extends into the compressor housing.

Advantageously, the suction pipe is guided in the sleeve until it approaches the suction opening, thereby ensuring that a sufficient compensation volume is available.

Advantageously, the integral design of the suction muffler and the compensation volume enables particularly low costs and the possibility of rapid production.

Advantageously, the compensation volume is formed with a volume equivalent to 0.5-1.2 times the piston working volume of the piston-cylinder unit to ensure that the refrigerant coming out of the suction pipe will not reach the compressor housing even when the suction valve is closed and has been heated refrigeration mix. At the same time ensure that no refrigerant is sucked from the compressor housing through the compensating volume into the muffler or cylinder during the suction process.

Advantageously, the resulting compensating volume is at least half, preferably 0.5-3 times, the working volume of the piston of the piston-cylinder unit, furthermore making it possible by providing the compensating volume due to the flow of refrigerant into the compensating volume and into the compressor housing The noise is minimized, so there is no disturbing noise to the operator, which is especially important for domestic refrigerators. In addition, in terms of production technology, a slightly larger compensation volume is easier to produce.

Advantageously, the smallest flow cross-section in the compensation volume has a cross-sectional area corresponding to 1/4-3/4 of the cross-sectional area of the suction opening. This ensures a small pressure difference, thereby reducing flow losses and increasing outward noise attenuation.

Advantageously, the cross-section of the compensation volume corresponds to at most 1.5 times the surface area of the piston head. This ensures, on the one hand, that the space required for the compensation volume is not too large, and, on the other hand, that the cold and hot intake gases do not mix or form a boundary layer as described below.

A preferred embodiment leading to particularly low flow losses is described by the following features: the compensation volume has a circular cross-section and the ratio of the length of the compensation volume to its diameter is greater than 10.

Description of drawings

Next, the present invention is described in more detail with reference to the accompanying drawings, wherein:

Figure 1 shows a side sectional view of a hermetically sealed refrigeration compressor according to the present invention;

Figure 2 shows a cross-sectional view of a suction muffler according to the prior art;

Figure 3 shows an alternative embodiment of a suction muffler according to the invention;

FIG. 4 shows another alternative embodiment of a suction muffler according to the invention.

Detailed ways

Figure 1 shows a cross-sectional view of a hermetically encapsulated refrigeration compressor. The piston-cylinder-motor unit is elastically supported by springs 2 inside the hermetically sealed compressor housing 1 .

The piston-cylinder-motor unit essentially consists of a cylinder housing 3 , a piston 4 reciprocating in the cylinder housing 3 , and a crankshaft bearing 5 mounted perpendicularly to the cylinder axis 6 . The crankshaft bearing 5 supports the crankshaft 7 and projects into the central bore 8 of the rotor 9 of the electric motor 10 . Located at the upper end of the crankshaft 7 is a connecting rod bearing 12 via which the connecting rod and thus the piston 4 are driven. Crankshaft 7 has lubrication holes 13 and is fastened to rotor 9 in region 14 . A suction muffler 16 is provided on the cylinder head 15, which minimizes noise generation during the refrigerant suction process.

FIG. 2 shows a sectional view of a suction muffler 16 according to the prior art. As shown in FIG. 1 , the suction muffler 16 is provided on the cylinder head 15 inside the hermetically sealed compressor housing 1 . When using this known suction muffler, the refrigerant coming out of the evaporator, which is cold compared to the hot refrigerant located in the compressor housing 1, passes through the suction pipe 17 near the inlet cross-section 18 of the suction muffler 16 It flows into the interior of the compressor housing 1 , where it mixes and heats up with the hot refrigerant already in the compressor housing 1 and is sucked into the piston-cylinder unit via the suction muffler 16 .

A suction muffler 16 according to the prior art generally comprises several volumes V ₁ , V ₂ , V _n connected in series and/or in parallel connected to each other by pipes, and an oil separator hole 31 at the lowest point. The cold refrigerant flows through the suction line 17 into the interior of the compressor housing 1 , where, depending on the design, the cold refrigerant first mixes with the hot refrigerant already present in the compressor housing 1 . The already mixed and heated refrigerant then flows through the inlet cross-section 18 into the first volume _V1 of the suction muffler, then into the second volume _V2 and remixes in _V1 and _V2 with the hot refrigerant already located there, This heats up the refrigerant again. In these known suction mufflers, the heating between the outlet in the suction pipe 17 and a short distance before the suction inlet 24 in the suction muffler 16 is between 30K and 40K, depending on the power of the refrigeration compressor.

In order to prevent undesired heating, a suction muffler 16 according to the invention is provided as shown in sectional view in FIG. 3 . A compensation volume 21 is connected to the suction muffler 16 which has an injection volume 20 (arrangements of several injection volumes are conceivable and common) and said compensation volume 21 has a cross-sectional constriction 32 . The compensation volume 21 and the suction muffler 16 are formed according to the invention by a sleeve 22 which on the one hand surrounds or opens into a suction opening 24 arranged in the valve plate 11 and on the other hand through the compensation opening 23 leads into the interior of the compressor housing 1 . The sleeve 22 surrounds the suction pipe 17 at least along an end section.

The cold refrigerant flowing out of the suction line 17 and out of the evaporator flows into the section of the sleeve 22 which forms the injection volume 20 of the suction muffler 16 throughout the suction cycle. During the subsequent compression cycle, the injection volume 20 of the suction muffler no longer receives any further refrigerant from the suction pipe 7 due to the closure of the suction valve, which means that the refrigerant retreats into the compensating volume 21 formed by a length of sleeve 22 cause, and extrude the hot refrigerant located therein into the interior of the compressor housing 1 through the compensation opening 23 .

This leads to the formation of a boundary layer 25 between the hot and cold refrigerant which is movable according to the suction cycle. During the next suction cycle, cold refrigerant can be sucked into the cylinder from the suction pipe 17 and from the compensating volume 21 of the sleeve 22 . It is important that the boundary layer 25 in the direction of the suction opening 24 does not exceed the line marked by the reference numeral 33 which, in this embodiment, forms simultaneously into the suction muffler 16 or between the injection volume 20 and the compensation volume 21 The inlet cross-section 18 of the transition opening 26 in order to prevent mixing of hot and cold refrigerant prior to the suction process.

At the same time, cold refrigerant is not allowed to enter the compressor housing 1 from the suction pipe 17 in the compensation volume 21 , so that the boundary layer 25 is not displaced behind the line marked with reference numeral 23 (compensation opening) in FIG. 3 . Regardless of the embodiment described, it is therefore necessary to adjust the volume of the compensation volume 21 exactly to the cooling capacity and thus to the working volume of the piston-cylinder unit.

FIG. 4 shows a further alternative embodiment of a suction muffler 16 with a compensating volume 21 , wherein the suction muffler 16 is formed from two volumes 20 and 20 a. In all other respects, this variant is identical to that shown in FIG. 3 . Here too, the boundary layer 25 must always fluctuate between the line marked with the reference numeral 23 and the inlet cross section 18 or the transition opening 26 depending on the intake cycle.

How the different compensating volumes 21 and the suction muffler 16 are designed is of secondary importance as long as the features of the invention are realized and the gas column or boundary layer 25 can fluctuate in the compensating volume. Therefore, as shown in FIG. 3 , an additional injection volume 27 can be provided in the suction muffler 16 .

In the embodiment according to FIG. 3 , the suction muffler 16 comprises only a substantially conically extending injection volume 20 , whereas in the embodiment shown in FIG. 4 it comprises an essentially conically extending injection volume 20 a and an injection volume 20 . It should be understood that a parallel or series configuration of the additional volume of the suction muffler 16 is possible at any time and results in improved sound attenuation performance of the suction muffler 16 .

Especially as shown in FIG. 3 , the closer the suction pipe is to the suction port 24 , the larger the compensating volume becomes (while the length of the sleeve 22 remains the same). Contrary to this, the filling volume 20 of the suction muffler 16 is reduced, which creates problems with sound. FIG. 4 therefore shows an alternative embodiment in which, as described above, the suction muffler 16 includes two volumes 20 and 20a. By moving the suction pipe 17 in the direction of the filling volume 20, the compensation volume 21 can be enlarged without at the same time suffering the disadvantage of noise.

In both cases ( FIGS. 3 and 4 ), the suction muffler 16 and the sleeve 22 are preferably constructed in one piece in order to simplify production. In the exemplary embodiment of FIG. 3 , the suction muffler 16 is additionally formed by a sleeve 22 .

Furthermore, it is important to adjust the compensation volume to the refrigeration capacity of the refrigeration compressor, in other words to the size of the piston-cylinder unit. Only at a ratio of 0.5-1.2 of the compensation volume 21 to the piston working volume of the piston-cylinder unit, an optimum function is guaranteed at the beginning of the suction process and the desired drop in the refrigerant temperature is ensured, since here it is guaranteed to prevent The undulating boundary layer 25 does not exceed any of the aforementioned boundaries.

Furthermore, if the noise level generated by the operation of the refrigeration compressor is reduced, it is necessary to set the ratio of the compensation volume 21 to the piston working volume of the piston-cylinder unit to 0.5-3.

Preferably, the compensating volume also has a circular cross section with a ratio of length to diameter greater than 10.

Claims (9)

1. A hermetically sealed refrigeration compressor having a hermetically sealed compressor housing (1) within which a piston-cylinder unit compressing refrigerant operates , and includes a suction valve with a suction port (24), which is set in the valve plate (11) of the piston-cylinder unit, wherein the cylinder head (15) of the piston-cylinder unit is provided with injection A suction muffler (16) of volume (20) through which the refrigerant flows to the suction valve of the piston-cylinder unit, wherein the suction muffler (16) has an inlet cross-section (18) through which the refrigerant flows The section (18) flows into the suction muffler (16) and provides a compensating volume (21) communicating with the interior of the suction muffler (16) and the compressor housing (1), in which compensating volume the refrigerant fluctuates, its characteristic In that the inlet cross-section (18) is at the same time the connection (26) between the compensation volume (21) and the injection volume (20), and the compensation volume (21) is formed by a sleeve (22) which ) on the one hand sealingly surrounds the suction inlet (24) or the inlet cross-section (18), and on the other hand surrounds the refrigerant suction pipe (17) at least along a section and points towards the compressor housing (1), said suction pipe being connected to The evaporator of the refrigeration compressor is connected and extends into the interior of the compressor housing (1). 2. The hermetically sealed refrigeration compressor as claimed in claim 1, characterized in that the suction line (17) is guided in the sleeve (22) until it approaches the suction opening (24). 3. The hermetically sealed refrigeration compressor as claimed in claim 1 or 2, characterized in that the bushing (22) and the suction muffler (16) are formed in one piece. 4. The hermetically sealed refrigeration compressor according to claim 1 or 2, characterized in that the compensation volume (21) is 0.5-1.2 times the piston working volume of the piston-cylinder unit. 5. The hermetically sealed refrigeration compressor as claimed in claim 1 or 2, characterized in that the compensation volume (21) is at least half of the piston working volume of the piston-cylinder unit. 6. The hermetically sealed refrigeration compressor according to claim 1 or 2, characterized in that the smallest flow cross-section (32) in the compensation volume (21) has a cross-sectional area corresponding to the suction opening (24) One quarter to three quarters of the cross-sectional area. 7. The hermetically sealed refrigeration compressor according to claim 1 or 2, characterized in that the cross-sectional area of the compensation volume (21) is at most 1.5 times the surface area of the piston head of the piston-cylinder unit piston. 8. The hermetically sealed refrigeration compressor according to claim 1 or 2, characterized in that the compensation volume (21) has a circular cross section and the ratio of the length of the compensation volume (21) to its diameter is greater than 10. 9. The hermetically sealed refrigerant compressor according to claim 5, characterized in that the compensation volume (21) is 0.5-3 times the piston working volume of the piston-cylinder unit.

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