Piston compressor

Abstract

A piston compressor having a crankcase bounding an inlet chamber, at least one suction chamber, and a crankshaft chamber forming an oil sump. The crankcase has an inlet opening emanating in the inlet chamber. A strainer is mounted in the inlet chamber. A strainer wall of the strainer has strainer openings via which, in use, sucked in inlet gas passes to subsequently flow to the at least one suction chamber. The strainer has a diameter and the strainer openings have dimensions such that, when the piston compressor is operating at maximum capacity, gas passing the strainer wall via the strainer openings from the interior of the strainer into the inlet chamber has a flow speed which is lower than an entrainment speed so that liquid drops remain on the strainer wall and are substantially not dragged along with the gas flow passing the strainer openings.

Description

FIELD

[0001] The present disclosure relates to a piston compressor.BACKGROUND

[0002] Applicant manufactures and sells piston compressors according to the pre-characterizing portion of claim 1. The known piston compressor comprises a crankcase bounding an inlet chamber, at least one suction chamber, and a crankshaft chamber forming an oil sump. The crankcase has an inlet opening emanating in the inlet chamber. The piston compressor further comprises a crankshaft mounted in the crankshaft chamber and at least one cylinder / piston-assembly each comprising a cylinder being mounted in the crankcase and a piston which is reciprocally movably mounted in the cylinder and driveably connected with the crankshaft. The known piston compressor further comprises at least one cylinder head which is mounted on an associated one of the at least one suction chamber. The at least cylinder / piston-assembly comprises a suction port with an associated suction valve. Each suction port fluidly connects an interior of the at least one cylinder with an associated one of the at least one suction chamber. The at least one cylinder / piston-assembly also comprises a discharge port with an associated discharge valve. Each discharge port fluidly connects the interior of the respective cylinder with an associated one of the at least one cylinder head chamber. A gas inlet pipe is connected to the crankcase so as to fluidly connect an inlet pipe flow channel bounded by the gas inlet pipe via the inlet opening in the crankcase to the inlet chamber. The piston compressor comprises a strainer which is mounted in the inlet chamber. The strainer comprises a strainer wall having a cylindrical shape defining a central strainer axis. One end of the cylindrically shaped strainer wall is open and defines a strainer inlet end. The inlet opening of the crankcase emanates in the strainer inlet end. The strainer wall has strainer openings via which, in use, sucked in inlet gas passes to subsequently flow to the at least one suction chamber.SUMMARY

[0003] Piston compressors may be used in numerous applications, e.g. in cooling installations for compression of a cooling fluid, and in other gas compression systems, for example, air compression systems.

[0004] The known piston compressor is able to compress a gas in which a certain amount of liquid may be present. The liquid may be condensate which has been formed upstream from the inlet opening of the piston compressor. The liquid may alternatively be another liquid which may be contained in the gas. However, the amount of liquid which may be present in the gas should not be so high that it enters the suction port of the piston / cylinder-assemblies. It is known to remove the liquid from the compressed gas, i.e. after compression. This is e.g. done in a gas / liquid-separator through which the compressed gas is guided.

[0005] The object of the present disclosure is to provide a piston compressor in which the amount of liquid which may be present per volume entity of inlet gas, expressed in e.g. l / m 3< or kg / m 3< , at the inlet opening of the piston compressor is higher than in the known piston compressors.

[0006] To that end, the piston compressor according to the pre-characterizing portion of claim 1 as described in the background section above is characterized in that, for collecting liquid entrained in the gas upstream from the suction ports, the strainer has a diameter and the strainer openings have dimensions such that, when the piston compressor is operating at maximum capacity, gas passing the strainer wall via the strainer openings from the interior of the strainer into the inlet chamber has a flow speed which is lower than an entrainment speed so that liquid drops remain on the strainer wall and are substantially not dragged along with the gas flow passing the strainer openings.

[0007] By virtue of the novel and specific strainer diameter and dimensions of the strainer openings the flow speed of the gas through the strainer openings remains so low under all circumstances that any liquid which is caught by the strainer and precipitates on the strainer wall is not entrained in the gas flowing through the strainer openings. Instead, the liquid which is caught by the strainer flows down over the strainer wall to the bottom side of the strainer under the effect of gravity. At the bottom side of the strainer, the liquid is collected and forms larger drops which, under the effect of gravity fall down. Thus, upstream of the suction ports of the piston / cylinder-assemblies, gas / liquid separation takes place by virtue of the specifically designed and dimensioned strainer.

[0008] In an embodiment, the diameter of the strainer wall and the dimensions of the strainer openings are such that the gas flow speed through the strainer openings is less than 1.7 m / s, preferably less than 1.5 m / s.

[0009] When the gas flow speed remains below the above-defined value, the chance of entrainment of liquid droplets in the gas flow passing through the strainer openings is minimized, thus ensuring that liquid caught by the strainer flows over the strainer wall to the bottom part of the strainer under the influence of gravity and will form larger liquid drops that will fall down from the strainer under the influence of gravity without being dragged along with the gas flow to the suction port or ports of the at least one cylinder / piston-assembly.

[0010] Other embodiments are described in the remaining dependent claims and will be further elucidated in the detailed description with reference to the examples shown in the accompanying figures.BRIEF DESCRIPTION OF THE FIGURES

[0011] Fig. 1 shows a cross sectional view of a piston compressor along a plane which is perpendicular to a rotational axis of the crankshaft of the piston compressor; Fig. 2 shows a similar cross-sectional view of the crankcase with the strainer of the piston compressor shown in Fig. 1; Fig. 3 shows a cross sectional view over line III-III in fig. 2; Fig. 4 shows a perspective view of the cross section shown in Fig. 2; Fig. 5 shows detail V from Fig. 2; and Fig. 6 shows detail VI from Fig. 1, in particular a suction port of a cylinder / piston-assembly. DETAILED DESCRIPTION

[0012] In the following detailed description reference will be made to the figures mentioned above. However, the various embodiments described herein are not limited to the example shown in the drawings. In fact, the reference numbers used in the detailed description are only present for elucidation and do not limit the described embodiments to the examples which are shown in the drawings.

[0013] In most general terms, the invention relates to a piston compressor 10. The piston compressor 10 comprises a crankcase 11 bounding an inlet chamber 34, at least one suction chamber 36, and a crankshaft chamber 40 forming an oil sump 42. The crankcase 11 has an inlet opening 22 emanating in the inlet chamber 34. The piston compressor further comprises a crankshaft 46 mounted in the crankshaft chamber 40 and at least one cylinder / piston-assembly 44, 48. Each cylinder / piston-assembly 44, 48 comprises a cylinder 44 which mounted in the crankcase 11 and a piston 48 which is reciprocally movably mounted in the cylinder 44 and driveably connected with the crankshaft 46. The piston compressor 10 further comprises at least one cylinder head 50 which is mounted on an associated one of the at least one suction chamber 36. The at least cylinder / piston-assembly 44, 48 comprises a suction port 54 with an associated suction valve 56. Each suction port 54 fluidly connects an interior of the at least one cylinder 44 with an associated one of the at least one suction chamber 36, 38. The at least one cylinder / piston-assembly 44, 48 additionally comprises a discharge port 58 with an associated discharge valve 60. Each discharge port 58 fluidly connects the interior of the respective cylinder 44 with an associated one of the at least one cylinder head chamber 50a, 52a. The piston compressor further comprises a gas inlet pipe 62 which is connected to the crankcase 11 so as to fluidly connect an inlet pipe flow channel 62c bounded by the gas inlet pipe 62 via the inlet opening 22 in the crankcase 11 to the inlet chamber 34. A strainer 64 is mounted in the inlet chamber 34. The strainer 64 comprises a strainer wall 66 having a cylindrical shape defining a central strainer axis. One end of the cylindrically shaped strainer wall 66 is open and defines a strainer inlet end 69. The inlet opening 22 of the crankcase 11 emanates in the strainer inlet end 69. The strainer wall 66 has strainer openings 68 via which, in use, sucked in inlet gas passes to subsequently flow to the at least one suction chamber 36, 38.

[0014] The piston compressor 10 is characterized in that for collecting liquid entrained in the gas upstream from the suction ports 54, the strainer 64 has a diameter and the strainer openings 68 have dimensions such that, when the piston compressor 10 is operating at maximum capacity, gas passing the strainer wall 66 via the strainer openings 68 from the interior of the strainer 64 into the inlet chamber 34 has a flow speed which is lower than an entrainment speed so that liquid drops remain on the strainer wall 66 and are substantially not dragged along with the gas flow passing the strainer openings 68.

[0015] The advantages which are associated with the piston compressor according to the invention are described in the summary section (page 3, 2 nd< paragraph) of this application and are for sake of brevity not repeated here but are considered to be included here by reference to the summary section.

[0016] In an embodiment, of which an example is shown in the figures, the piston compressor 10 may, for collecting liquid entrained in the gas upstream from the suction ports 54, comprise a cone-shaped body 70 having a central cone-axis which coincides with the central strainer axis. A first end of the cone-shaped body 70 with the smallest diameter is at the strainer inlet end. A second end of the cone-shaped body 70 with the largest diameter is at the other end of the strainer 64, opposite the strainer inlet end.

[0017] The cone-shaped body 70 may be a true cone including the tip a mathematical cone shape. However, the cone-shaped body 70 may alternatively have a rounded tip. In yet another embodiment, the cone-shaped body 70 may be a frusto-conical body. In the example shown in the figures, the cone-shaped body 70 resembles a cone-shaped body 70 with a rounded tip portion adjacent the strainer inlet end. By virtue of the presence of the cone-shaped body 70 within the cylindrical strainer 64, the flow speed of the gas through the strainer openings 68 remains substantially constant both at the inlet end of the strainer 64 as well as at the end of the strainer opposite the strainer inlet end 69. In other words, the gas which is supplied via the inlet opening 22 into the strainer 64 has a flow direction which is substantially in the axial direction of the strainer 64. However, gas is leaving the strainer 64 via the strainer openings. The cone-shaped body 70 provides a diminishing flow cross section when viewed in the axial direction of the strainer from the strainer inlet end 69 to the opposite end of the strainer. Thus, the static and dynamic pressure prevailing in the strainer at various positions thereof along the length of the strainer 64 is kept substantially constant even though gas is leaving the strainer 64 via the strainer openings 68. Thus, an improved, substantially constant gas outflow speed through the strainer openings 68 over the length of the strainer 64 is obtained and the supply of gas to the suction chambers 36, 38 may be substantially constant over the entire length of the piston compressor 10.

[0018] In an embodiment, of which an example is shown in the figures, the piston compressor 10 may, for collecting liquid entrained in the gas upstream from the suction ports 54, be configured such that a smallest flow distance between the strainer 64 and any one of the suction ports 54 is such that any liquid droplets released from the strainer 64 and dragged along with the gas flow fall down before they reach the suction ports 54.

[0019] In the unlikely event that a liquid droplet would be released from the strainer 64 and entrained in the gas flow, for example when a shock wave in the gas flow occurs due to some switching in a downstream compressed gas channel system or in an upstream suction channel system, this embodiment further reduces the chance that liquid reaches the suction ports 54. Thus, the chance of consequential damage may be reduced.

[0020] In an embodiment, of which an example is shown in the figures, the gas inlet pipe 62 may have an inlet end 62a with a flange 88 and an outlet end 62b which is connected to the crankcase 11. The gas inlet pipe 62 may be elbow shaped and the inlet pipe flow channel 62c thereof defines an inlet pipe flow channel center axis L3 which is bent over 90 degrees. For collecting liquid entrained in the gas upstream from the suction ports 54, the flange 88 may be offset relative to the inlet pipe flow channel center axis L3 towards an outside bend part 62d of the gas inlet pipe 62 so as to promote liquid collection on the outside bend part 62d of the gas inlet pipe 62.

[0021] By virtue of such a configuration of the gas inlet pipe 62, any liquid entrained in the suction flow with the gas inlet pipe 62 will be forced by centrifugal forces towards the wall of the inlet pipe, in particular to the part 62d of the wall which bounds the outer side of the bent. The chance that the droplets will indeed reach the wall of the inlet pipe is increased due to the fact that the flange 88 is offset relative to the inlet pipe flow channel center axis L3 towards the outside bend part 62d. This will lead to the collection of more small droplets on the wall of the inlet pipe and a liquid stream will be formed already in the gas inlet pipe 62. This liquid stream will enter the strainer 64 at the bottom side thereof and subsequently leave the strainer due to gravity as large, heavy droplets or even a stream of liquid. These large, heavy droplets or stream of liquid will not be entrained by the gas stream leaving the strainer openings 68 and therefore not reach the suction ports 54 of the cylinder / piston assemblies

[0022] In an embodiment, of which an example is shown in the figures, the elbow shaped gas inlet pipe 62 may, for collecting liquid entrained in the gas upstream from the suction ports 54, bound an inlet pipe flow channel 62c having a diverging cross section from the inlet end 62a towards the outlet end 62b so as to reduce the flow speed of gas therein. This diverging cross section may be applied independently from the offset-flange embodiment described above or in combination therewith. The divergent cross section of the of the inlet pipe flow channel 62c indeed causes that the flow speed of the gas therein decreases upon flowing from the inlet end 62a towards the outlet end 62b. Due to the reducing gas flow speed, the chance that droplets which are entrained in the gas flow fall down and are collected on the bottom part of the pipe wall of the gas inlet pipe 62 is larger than without the decreasing gas flow speed. Thus, also this feature improves the collection of liquid before the liquid can reach the suction ports 54 of the at least one cylinder / piston-assembly.

[0023] In an embodiment, the piston compressor 10 may comprise an electronic controller 90 and a temperature sensor 92 for measuring a temperature of oil in the oil sump 42. The electronic controller 90 is configured for switching off the piston compressor 10 when the oil temperature falls below 30°C.

[0024] Liquid which is collected before it reaches the suction ports 54, will first be stored at various liquid buffer reservoirs 72, 74, 76 within the crankcase 11 and of which embodiments will be described below. In these liquid buffer reservoirs 72, 74, 76, the liquid may evaporate. However, if the supply of liquid exceeds the evaporation rate, in the end the liquid buffer reservoirs 72, 74, 76 may overflow and the liquid will end up in the oil sump 42. Consequently, the temperature of the oil in the oil sump may be indicative for the amount of liquid which has been discharged from one or more of the liquid buffer reservoirs 72, 74, 76 into the oil sump 42. When the oil temperature falls below the claimed temperature, this may, according to the present embodiment, be an indication that there may be a problem with the amount of liquid in the supply gas flow and that the piston compressor 10 should be switched off to prevent damage of, or other problems with the piston compressor 10.

[0025] In an embodiment, of which an example is shown in the figures, a lower part of the inlet chamber 34 may form an inlet chamber liquid buffer reservoir 72 for collecting liquid entrained in the gas upstream from the suction ports 54.

[0026] In an embodiment, of which an example is shown in the figures, a lower part of the at least one suction chamber 36, 38 may form a suction chamber liquid buffer reservoir 74, 76 for collecting liquid entrained in the gas upstream from the suction ports 54.

[0027] In a further elaboration of the embodiment with the suction chamber liquid buffer reservoir 74, 76, a wall separating the at least one suction chamber 36, 38 from the crankshaft chamber 40 and bounding the suction chamber liquid buffer reservoir 74, 76 may comprise a pressure balancing opening 80 connecting the at least one suction chamber 36, 38 with the crankshaft chamber 40. The pressure balancing opening 80 may be positioned at such a height above a bottom of the at least one suction chamber 36, 38 that each suction chamber liquid buffer reservoir 74, 76 has a capacity of at least 0.5 l per cylinder 44, preferably more than 1 l per cylinder 44, more preferably at least 1.5 l per cylinder 44.

[0028] In an alternative further elaboration of the embodiment with the suction chamber liquid buffer reservoir 74, 76, the wall separating the at least one suction chamber 36, 38 from the crankshaft chamber 40 and bounding the suction chamber liquid buffer reservoir 74, 76 may comprise a pressure balancing opening 80 connecting the at least one suction chamber 36, 38 with the crankshaft chamber 40 as is the case with the previous further elaboration of the embodiment. However, in this alternative, in each pressure balancing opening a bush 82 is provided with a bush inlet opening 84 in the respective suction chamber and an bush outlet opening 86 in the crankshaft chamber 40. The bush inlet opening 84 in each bush 82 is positioned at such a height above a bottom of the respective at least one suction chamber 36, 38 that each suction chamber liquid buffer reservoir 74, 76 has a capacity of at least 0.5 l per cylinder 44, preferably more than 1 l per cylinder 44, more preferably at least 1.5 l per cylinder 44.

[0029] In either further elaboration as described above, the amount of liquid which can be buffered in the suction chamber liquid buffer reservoirs 74, 76 is quite high which means that it will take more time before the suction chamber liquid buffer reservoirs overflow and liquid is discharged in the oil sump 42. The more liquid can be stored in the suction chamber liquid buffer reservoirs 74, 76, the longer the time available for evaporation, and thus the greater the chance that the liquid evaporates before the suction chamber liquid buffer reservoir 74, 76 overflows. Thus, undesired switching off of the piston compressor 10 may be prevented due to the large liquid buffer capacity.

[0030] In an embodiment, of which an example is shown in the figures, the piston compressor may have a V-configuration. In such a configuration, the crankcase 11 may comprises a main body 12 defined by a main body wall 14 which extends along a longitudinal main axis L1 of the main body 12. The main body 12 comprises first cylinder receiving recesses 16. The crankcase 11 further comprises a first end wall 18 and a second end wall 20 which close off two opposite ends of the main body 12. The first end wall 18 comprises the inlet opening 22. Further, the crankcase 11 includes a cylinder support 24 which has an inverted V-shape in cross-section along a plane perpendicular to the longitudinal main axis L1. The cylinder support 24 has two longitudinal edges 24a, 24b extending parallel to the longitudinal main axis L1. The two longitudinal edges 24a, 24b are connected to the main body wall 14. Further, the cylinder support 24 has two opposite end edges 24c which are respectively connected to the two opposite first and second end walls 18, 20. The cylinder support 24 includes second cylinder receiving recesses 26. The crankcase 14 additionally comprises a first reinforcement wall 28 and a second reinforcement wall 30 each extending parallel to longitudinal main axis L1 and each having a first longitudinal edge 28a, 30a, a second longitudinal edge 28b, 30b and two opposite end edges. The first longitudinal edge 28a, 30a of each reinforcement wall 28, 30 is connected with the cylinder support 24 and the second longitudinal edge 28b, 30b is connected with the main body wall 14. The opposite end edges are connected to the first and second end walls 18, 20. Both the first reinforcement wall 28 and the second reinforcement wall 30 include gas passage openings 32. In this configuration, the inlet chamber 34 is bounded by an upper part of main body wall 14, the two reinforcement walls and an upper part of the cylinder support 24. The inlet chamber 34 extends parallel to the longitudinal main axis L1 from the first end wall 18 to the second end wall 20. The at least one suction chamber 36, 38 comprises a first suction chamber 36 and a second suction chamber 38. The first suction chamber 36 is bounded by a first part of the cylinder support 24, the first reinforcement wall 28 and a first suction chamber bounding part of the main body wall 14. The first suction chamber 36 extends parallel to the longitudinal main axis L1 from the first end wall 18 to the second end wall 20. The second suction chamber 38 is bounded by a second part of the cylinder support 24, the second reinforcement wall 30 and a second suction chamber bounding part of main body wall 14. The second suction chamber 38 extends parallel to the longitudinal main axis L1 from the first end wall 18 to the second end wall 20. In this embodiment, the crankshaft chamber 40 is bounded by the cylinder support 24 and by a crankshaft chamber bounding part of the main body wall 14.

[0031] This embodiment of the crankcase 11 is strong and stiff and provides internal gas flow passage ways which may be relatively wide so the gas flow speed may be relatively low, thus preventing or at least reducing entrainment of liquid droplets in the gas flow within the piston compressor 10. The various liquid buffer reservoirs 72, 74, 76 are formed by structural parts of the crankcase 11 which are provided in the crankcase 11 for providing support for the cylinders 44 (the cylinder support 24) and for providing extra stiffness to the crankcase 11 (the first and second reinforcement walls 28, 30). Thus, the liquid buffer reservoirs 72 74, 76 are formed with a minimum of additional parts and thus with minimal extra manufacturing costs.

[0032] In an embodiment, of which an example is shown in the figures, the main body wall 14, the first and second end wall 18, 20, the cylinder support 24 may comprise bended steel sheet. The first and second reinforcement walls 28, 30 may also comprise flat or bended steel sheet. This has the advantage of relatively low manufacturing costs and very good heat conduction to the environment. The connections between the main body wall 14, the first and second end walls 18, 20, the cylinder support 24 and the first and second reinforcement walls 28, 30 may be weld connections. The main body 12 may have a substantially constant cross section along any cross sectional plane which extends perpendicular to the main axis L1.

[0033] In a further elaboration of the embodiment with the V-shaped configuration, the first longitudinal edges 28a, 30a of both the first and the second reinforcement walls 28, 30 are connected with the cylinder support 24 at intermitted connection sections 28d, 30d. Between the intermitted connection sections 28d, 30d liquid transmissive slits 28e, 30e are present separating the respective first longitudinal edges 28a, 30a and the cylinder support 24. Also the opposite end edges of both the first and the second reinforcement walls 28, 30 are connected to the first and second end walls 18, 20 in a fluid tight manner thereby providing the inlet chamber liquid buffer reservoir 72 in the lower part of the inlet chamber 34. The inlet chamber liquid buffer reservoir 72 extends from the first end wall 18 to the second end wall 20. Thus, in a very efficient manner, the inlet chamber liquid buffer reservoir 72 is created from parts of the crankcase 11 which are present anyway for other purposes, namely reinforcement walls 28, 30 and cylinder support 24. This is beneficial both with respect to material use and costs as well as manufacturing time and costs. The liquid transmissive slits 28e, 30e enable liquid which is collected in the inlet chamber liquid buffer reservoir 72 to slowly flow out of the inlet chamber liquid buffer reservoir 72 over the cylinder support 24. During the flow of the liquid over cylinder support 24, part of the liquid may evaporate which contributes to the solution of unwanted liquid ending up in the suction ports 54. Additionally, the evaporating liquid cools the cylinder support 24. Since oil from the oil sump 42 and the rotating crankshaft 46 will splash against cylinder support 24, the cooling of the cylinder support 24 due to the evaporating liquid flowing over it will contribute to cooling of the oil, which is advantageous for prevention of overheating of the oil and thus for the lifetime of the oil. Liquid which is not evaporated during flowing down over the cylinder support 24 is collected in the first and second suction chamber liquid buffer reservoirs 74, 76 where it has further time to remain which may provide the possibility to evaporate.

[0034] In an embodiment, the gas passage openings 32 in the first reinforcement wall 28 and the gas passage openings 32 in the second reinforcement wall 30 have dimensions which are such that, when the piston compressor 10 is operating at maximum capacity, gas passing these gas passage openings 32 from the inlet chamber 34 into the first and the second suction chambers 36, 38 has a flow speed which is lower than an entrainment speed so that substantially no liquid drops are dragged along with the gas flow passing the gas passage openings 32.

[0035] Again, this is to minimize the risk of liquid being sucked into the cylinders via the suction ports 54. Due to the relatively low flow speed, any droplets within the gas flow will be more likely to fall down under the influence of gravity than to be transported by the gas flow to the suction ports 54.

[0036] In yet another embodiment, similarly, each longitudinal edge 24a, 24b of the cylinder support 24 may be connected with the main body wall 14 along its entire length in a fluid tight manner. Again, the two opposite end edges 24c of the cylinder support 24 are respectively connected to the two opposite end walls 18, 20 in a fluid tight manner, thereby providing a first suction chamber liquid buffer reservoir 74 in the lower part of the first suction chamber 36, and a second suction chamber liquid buffer reservoir 76 in the lower part of the second suction chamber 38. The first and the second suction chamber liquid buffer reservoirs 74, 76 each extending from the first end wall 18 to the second end wall 20. Thus, again, in a very efficient manner, the suction chamber liquid buffer reservoirs 74, 76 are created from parts of the crankcase 11 which are present anyway for other purposes, namely main body wall 14 and cylinder support 24. This is beneficial both with respect to material use and costs as well as manufacturing time and costs.

[0037] Although illustrative embodiments of the present invention have been described above, in part with reference to the accompanying figures, it is to be understood that the invention is not limited to these embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0038] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this description are not necessarily all referring to the same embodiment. Furthermore, it is noted that particular features, structures, or characteristics of one or more of the various embodiments which are described above may be used implemented independently from one another and may be combined in any suitable manner to form new, not explicitly described embodiments. The reference numbers used in the detailed description and the claims do not limit the description of the embodiments, nor do they limit the claims. The reference numbers are solely used to clarify.List of Elements

[0039] 10.Piston compressor 11.Crankcase 12.Main body 14.Main body wall 16.First cylinder receiving recesses 18.First end wall 20.Second end wall 22.Inlet opening in first end wall 24.Cylinder support 24a.First longitudinal edge of the cylinder support 24b.Second longitudinal edge of the cylinder support 24c.Opposite end edges of the cylinder support 26.Second cylinder receiving recesses 28.First reinforcement wall 28a.First longitudinal edge of first reinforcement wall 28b.Second longitudinal edge of first reinforcement wall 30.Second reinforcement wall 30a.First longitudinal edge of second reinforcement wall 30b.Second longitudinal edge of second reinforcement wall 32.Gas passage openings 34.Inlet chamber 36.First suction chamber 38.Second suction chamber 40.Crankshaft chamber 42.Oil sump 44.Cylinder 46.Crankshaft 48.Piston 50.First cylinder head 50a.First cylinder head chamber 52.Second cylinder head 52a.Second cylinder head chamber 54.Suction ports 56.Suction valve 58.Discharge port 60.Discharge valve 62.Gas inlet pipe 62a.Inlet end of gas inlet pipe 62b.Outlet end of gas inlet pipe 62c.Inlet pipe flow channel 62d.Outside bend part of the gas inlet pipe 64.Strainer 66.Strainer wall 68.Strainer openings 69.Strainer inlet end 70.Cone-shaped body 72.Inlet chamber liquid buffer reservoir 74.First suction chamber liquid buffer reservoir 76.Second suction chamber liquid buffer reservoir 78.First pressure balancing opening 80.Second pressure balancing opening 82.Bush 84.Bush inlet opening 86.Bush outlet opening 88.Flange of the gas inlet pipe 90.Electronic controller 92.Temperature sensor L1.Longitudinal main axis L3.Inlet pipe flow channel center axis

Claims

1. A piston compressor (10) the piston compressor (10) comprising: a crankcase (11) bounding an inlet chamber (34), at least one suction chamber (36), and a crankshaft chamber (40) forming an oil sump (42), the crankcase (11) having an inlet opening (22) emanating in the inlet chamber (34); a crankshaft (46) mounted in the crankshaft chamber (40); at least one cylinder / piston-assembly (44, 48) each comprising a cylinder (44) being mounted in the crankcase (11) and a piston (48) which is reciprocally movably mounted in the cylinder (44) and driveably connected with the crankshaft (46); at least one cylinder head (50, 52) being mounted on an associated one of the at least one suction chamber (36, 38); the at least cylinder / piston-assembly (44, 48) comprising a suction port (54) with an associated suction valve (56), wherein each suction port (54) fluidly connects an interior of the at least one cylinder (44) with an associated one of the at least one suction chamber (36, 38); the at least one cylinder / piston-assembly (44, 48) comprising a discharge port (58) with an associated discharge valve (60), wherein each discharge port (58) fluidly connects the interior of the respective cylinder (44) with an associated one of the at least one cylinder head chamber (50a, 52a); a gas inlet pipe (62) which is connected to the crankcase (11) so as to fluidly connect an inlet pipe flow channel (62c) bounded by the gas inlet pipe (62) via the inlet opening (22) in the crankcase (11) to the inlet chamber (34); a strainer (64) which is mounted in the inlet chamber (34), the strainer (64) comprising a strainer wall (66) having a cylindrical shape defining a central strainer axis, one end of the cylindrically shaped strainer wall (66) being open and defining an strainer inlet end (69), the inlet opening (22) of the crankcase (11) emanating in the strainer inlet end (69), the strainer wall (66) having strainer openings (68) via which, in use, sucked in inlet gas passes to subsequently flow to the at least one suction chamber (36, 38); characterized in that for collecting liquid entrained in the gas upstream from the suction ports (54), the strainer (64) has a diameter and the strainer openings (68) have dimensions such that, when the piston compressor (10) is operating at maximum capacity, gas passing the strainer wall (66) via the strainer openings (68) from the interior of the strainer (64) into the inlet chamber (34) has a flow speed which is lower than an entrainment speed so that liquid drops remain on the strainer wall (66) and are substantially not dragged along with the gas flow passing the strainer openings (68).

2. The piston compressor (10) according to claim 1, wherein the diameter of the strainer wall and the dimensions of the strainer openings are such that the gas flow speed through the strainer openings is less than 1.7 m / s, preferably less than 1.5 m / s.

3. The piston compressor (10) according to claim 1 or 2, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), the piston compressor (10) comprises a cone-shaped body (70) having a central cone-axis which coincides with the central strainer axis, wherein a first end of the cone-shaped body (70) with the smallest diameter is at the strainer inlet end and wherein a second end of the cone-shaped body (70) with the largest diameter is at the other end of the strainer (64), opposite the strainer inlet end.

4. The piston compressor (10) according to any one of the preceding claims, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), a smallest flow distance between the strainer (64) and any one of the suction ports (54) is such that any liquid droplets released from the strainer (64) and dragged along with the gas flow fall down before they reach the suction ports (54).

5. The piston compressor (10) according to any one of the preceding claims, wherein the gas inlet pipe (62) has an inlet end (62a) with a flange (88) and an outlet end (62b) which is connected to the crankcase (11), wherein the gas inlet pipe (62) is elbow shaped and the inlet pipe flow channel (62c) thereof defines an inlet pipe flow channel center axis (L3) which is bent over 90 degrees, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), the flange (88) is offset relative to the inlet pipe flow channel center axis (L3) towards an outside bend part (62d) of the gas inlet pipe (62) so as to promote liquid collection on the outside bend part (62d) of the gas inlet pipe (62).

6. The piston compressor (10) according to any one of the preceding claims, wherein the gas inlet pipe (62) has an inlet end (62a) with a flange (88) and an outlet end (62b) which is connected to the crankcase (11), wherein the gas inlet pipe (62) is elbow shaped and the inlet pipe flow channel (62c) thereof defines an inlet pipe flow channel center axis (L3) which is bent over 90 degrees, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), the inlet pipe flow channel (62c) has a diverging cross section from the inlet end (62a) towards the outlet end (62b) so as to reduce the flow speed of gas therein.

7. The piston compressor (10) according to any one of the preceding claims, comprising an electronic controller (90) and a temperature sensor (92) for measuring a temperature of oil in the oil sump (42), wherein the electronic controller (90) is configured for switching off the piston compressor (10) when the oil temperature falls below 30 °C.

8. The piston compressor (10) according to any one of the preceding claims, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), a lower part of the inlet chamber (34) forms an inlet chamber liquid buffer reservoir (72).

9. The piston compressor (10) according to any one of the preceding claims, wherein for collecting liquid entrained in the gas upstream from the suction ports (54), a lower part of the at least one suction chamber (36, 38) forms a suction chamber liquid buffer reservoir (74, 76).

10. The piston compressor (10) according to claim 9, wherein a wall separating the at least one suction chamber (36, 38) from the crankshaft chamber (40) and bounding the suction chamber liquid buffer reservoir (74, 76) comprises a pressure balancing opening (80) connecting the at least one suction chamber (36, 38) with the crankshaft chamber (40), the pressure balancing opening (80) being positioned at such a height above a bottom of the at least one suction chamber (36, 38) that each suction chamber liquid buffer reservoir (74, 76) has a capacity of at least 0.5 l per cylinder (44), preferably more than 1 l per cylinder (44), more preferably at least 1.5 l per cylinder (44).

11. The piston compressor (10) according to claim 9, wherein a wall separating the at least one suction chamber (36, 38) from the crankshaft chamber (40) and bounding the suction chamber liquid buffer reservoir (74, 76) comprises a pressure balancing opening (80) connecting the at least one suction chamber (36, 38) with the crankshaft chamber (40), wherein in each pressure balancing opening a bush (82) is provided with a bush inlet opening (84) in the respective suction chamber and an bush outlet opening (86) in the crankshaft chamber (40), wherein the bush inlet opening (84) in each bush (82) is positioned at such a height above a bottom of the respective at least one suction chamber (36, 38) that each suction chamber liquid buffer reservoir (74, 76) has a capacity of at least 0.5 l per cylinder (44), preferably more than 1 l per cylinder (44), more preferably at least 1.5 l per cylinder (44).

12. The piston compressor according to any one of the preceding claims, wherein the piston compressor has a V-configuration, wherein the crankcase (11) comprises: a main body (12) defined by a main body wall (14) which extends along a longitudinal main axis (L1) of the main body (12), the main body (12) comprising first cylinder receiving recesses (16); a first end wall (18) and a second end wall (20) which close off two opposite ends of the main body (12), the first end wall (18) comprising the inlet opening (22); a cylinder support (24) which has an inverted V-shape in cross-section along a plane perpendicular to the longitudinal main axis (L1), wherein the cylinder support (24) has two longitudinal edges (24a, 24b) extending parallel to the longitudinal main axis (L1) and being connected to the main body wall (14), wherein the cylinder support (24) has two opposite end edges (24c) which are respectively connected to the two opposite first and second end walls (18, 20), the cylinder support (24) including second cylinder receiving recesses (26); a first reinforcement wall (28) and a second reinforcement wall (30) each extending parallel to longitudinal main axis (L1) and each having a first longitudinal edge (28a, 30a), a second longitudinal edge (28b, 30b) and two opposite end edges, wherein the first longitudinal edge (28a, 30a) of each reinforcement wall (28, 30) is connected with the cylinder support (24) and the second longitudinal edge (28b, 30b) is connected with the main body wall (14), wherein the opposite end edges are connected to the first and second end walls (18, 20), both the first reinforcement wall (28) and the second reinforcement wall (30) including gas passage openings (32); the inlet chamber (34) being bounded by an upper part of main body wall (14), the two reinforcement walls and an upper part of the cylinder support (24), the inlet chamber (34) extending parallel to the longitudinal main axis (L1) from the first end wall (18) to the second end wall (20); the at least one suction chamber (36, 38) comprising a first suction chamber (36) being bounded by a first part of the cylinder support (24), the first reinforcement wall (28) and a first suction chamber bounding part of the main body wall (14), the first suction chamber (36) extending parallel to the longitudinal main axis (L1) from the first end wall (18) to the second end wall (20); the at least one suction chamber (36, 38) comprising a second suction chamber (38) which is bounded by a second part of the cylinder support (24), the second reinforcement wall (30) and a second suction chamber bounding part of main body wall (14), the second suction chamber (38) extending parallel to the longitudinal main axis (L1) from the first end wall (18) to the second end wall (20); the crankshaft chamber (40) being bounded by the cylinder support (24) and by a crankshaft chamber bounding part of the main body wall (14).

13. The piston compressor according to claim 12, wherein the main body wall (14), the first and second end wall (18, 20), the cylinder support (24) comprise bended steel sheet, and the first and second reinforcement walls (28, 30) comprise flat or bended steel sheet, the connections between the main body wall (14), the first and second end walls (18, 20), the cylinder support (24) and the first and second reinforcement walls (28, 30) being weld connections, the main body (12) having a substantially constant cross section along any cross sectional plane which extends perpendicular to the main axis (L1).

14. The piston compressor (10) according to any one of claims 12 and 13, wherein the first longitudinal edges (28a, 30a) of both the first and the second reinforcement walls (28, 30) are connected with the cylinder support (24) at intermitted connection sections (28d, 30d), wherein between the intermitted connection section liquid transmissive slits (28e, 30e) are present separating the respective first longitudinal edges (28a, 30a) and the cylinder support (24), wherein the opposite end edges of both the first and the second reinforcement walls (28, 30) are connected to the first and second end walls (18, 20) in a fluid tight manner thereby providing the inlet chamber liquid buffer reservoir (72) in the lower part of the inlet chamber (34), the inlet chamber liquid buffer reservoir (72) extending from the first end wall (18) to the second end wall (20).

15. The piston compressor (10) according to any one of claims 12-14, wherein the gas passage openings (32) in the first reinforcement wall (28) and the gas passage openings (32) in the second reinforcement wall (30) have dimensions which are such that, when the piston compressor (10) is operating at maximum capacity, gas passing these gas passage openings (32) from the inlet chamber (34) into the first and the second suction chambers (36, 38) has a flow speed which is lower than an entrainment speed so that substantially no liquid drops are dragged along with the gas flow passing the gas passage openings (32).

16. The piston compressor (10) according to any one claims 12-15, when dependent from claim 9, wherein each longitudinal edge (24a, 24b) of the cylinder support (24) is connected with the main body wall (14) along its entire length in a fluid tight manner, and the two opposite end edges (24c) of the cylinder support (24) are respectively connected to the two opposite end walls (18, 20) in a fluid tight manner, thereby providing a first suction chamber liquid buffer reservoir (74) in the lower part of the first suction chamber (36), and a second suction chamber liquid buffer reservoir (76) in the lower part of the second suction chamber (38), the first and the second suction chamber liquid buffer reservoirs (74, 76) each extending from the first end wall (18) to the second end wall (20).

Images