Refrigerant compressor including an oil level sensor device

Abstract

A refrigerant compressor comprises a compressor housing (2), an oil sump (13) arranged in the compressor housing (2), and an oil level sensor device (14) configured to detect an oil level in the oil sump (13), the oil level sensor device (14) comprising a tubular element (16) fixed to the compressor housing (2) and a floating element (17) surrounding the tubular element (16) and movably mounted relative to the tubular element (16). The compressor housing (2) comprises a passage opening (24), and the dimensions of the tubular element (16), the dimensions of the floating element (17) and the dimensions of the passage opening (24) are defined to allow the tubular element (16) and the floating element (17) to be inserted into and removed from the compressor housing (2) through the passage opening (24).

Description

TECHNICAL FIELD

[0001] The present invention relates to a refrigerant compressor, such as a hermetic scroll compressor, comprising an oil level sensor device. BACKGROUND

[0002] CN 212867870 U discloses a refrigerant compressor comprising a compressor housing, an oil sump arranged in a lower part of the compressor housing, and an oil level sensor device positioned in the lower part of the compressor housing and configured to detect an oil level in the oil sump of the refrigerant compressor.

[0003] The oil level sensor device comprises a tubular element fixed to a bottom surface of the compressor housing, a magnetically sensitive sensor arranged inside the tubular element, and a magnetic floating element encircling the tubular element and slidably mounted with respect to the tubular element along a displacement direction, the floating element being configured to float on lubricating oil contained in the oil sump. The oil level sensor device further comprises a feedthrough formed in the bottom surface of the compressor housing for a sensor output line connectable to a controller of the refrigerant compressor.

[0004] The tubular element and the magnetic floating element of such an oil level sensor device cannot be accessed from the outside of the refrigerant compressor. Therefore, such an oil level sensor device cannot be replaced in case of malfunction, although it represents a relatively inexpensive component compared to the overall cost of the refrigerant compressor. The risk of malfunction of such an oil level sensor device is not negligible due to the fact that hermetic refrigerant compressors, especially of larger capacity, are in operation for many years. SUMMARY

[0005] It is an object of the present invention to provide an improved refrigerant compressor which can overcome the drawbacks encountered in conventional refrigerant compressors.

[0006] It is a further object of the present invention to provide a refrigerant compressor having an improved lifetime while limiting the manufacturing costs of the refrigerant compressor.

[0007] According to the invention, such a refrigerant compressor comprises:

[0008] - a compressor housing;

[0009] - an oil sump arranged in a lower part of the compressor housing; and

[0010] - an oil level sensor device configured to detect an oil level in the oil sump, the oil level sensor device comprising a tubular element and a floating element, the tubular element being fixed to the compressor housing and being arranged at least partially inside the compressor housing, the floating element being arranged around the tubular element and being movably mounted with respect to the tubular element, the floating element being configured to float on lubricating oil contained in the oil sump;

[0011] wherein the compressor housing comprises a passage opening, and the dimensions of the tubular element, the dimensions of the floating element and the dimensions of the passage opening are defined so as to allow the tubular element and the floating element to be inserted into and removed from the compressor housing through the passage opening.

[0012] Thanks to this configuration of the oil level sensor device according to the application, the tubular element and the floating element can be easily removed from the compressor housing and, therefore, easily replaced with new tubular elements and / or new floating elements in case of malfunction of the oil level sensor device. Thus, proper functioning and control of the refrigerant compressor according to the application can be maintained during the entire lifetime of the refrigerant compressor.

[0013] The refrigerant compressor can further comprise one or more of the following features, alone or in combination.

[0014] According to an embodiment of the application, the floating element is slidably mounted with respect to the tubular element along a displacement direction.

[0015] According to an embodiment of the application, the refrigerant compressor comprises a controller configured to control operation of the refrigerant compressor. The controller can be configured to control operation of the refrigerant compressor based on the oil level detected by the oil level sensor device.

[0016] According to an embodiment of the application, the compressor housing is provided with a suction inlet configured to supply the refrigerant compressor with refrigerant gas to be compressed, and a discharge outlet configured to discharge compressed refrigerant gas.

[0017] According to an embodiment of the application, the floating element is a magnetic floating element.

[0018] According to an embodiment of the application, the displacement direction of the floating element extends substantially parallel to a longitudinal axis of the refrigerant compressor.

[0019] According to an embodiment of the application, the floating element comprises a floating body and a magnet element fixed to the floating body.

[0020] According to embodiments of the present application, the float body includes a central through passage, the tubular element extending into the central through passage.

[0021] According to embodiments of the present application, the magnet element includes a plurality of permanent magnets angularly distributed around a central through passage provided on the float body. Alternatively, the magnet element includes a ring-shaped permanent magnet provided coaxially with a central through passage provided on the float body.

[0022] According to embodiments of the present application, the magnet element is at least partially arranged within the float body, and for example encapsulated within the float body.

[0023] According to embodiments of the present application, the oil level sensor device includes a magnetically sensitive sensor arranged inside the tubular element, and configured to be activated by a magnetic field provided by the magnet element.

[0024] According to embodiments of the present application, the magnetically sensitive sensor is a magnetically operated electrical switch, and for example a magnetic reed switch.

[0025] According to embodiments of the present application, the magnetically sensitive sensor is a Hall sensor.

[0026] According to embodiments of the present application, the passage opening is provided at a mid-shell or base plate of the compressor housing.

[0027] According to embodiments of the present application, the compressor housing further includes an upper cover and a base plate fixed to an upper end portion and a lower end portion of the mid-shell, respectively.

[0028] According to embodiments of the present application, the mid-shell is generally cylindrical.

[0029] According to embodiments of the present application, the passage opening is provided at a flat surface portion of the mid-shell.

[0030] According to embodiments of the present application, the oil level sensor device further includes a support member, such as a support sleeve, fixed and for example welded to the passage opening, the support member including an axial through passage, and configured to allow insertion and removal of the tubular element and the float element through the axial through passage, the tubular element being attached to the support member

[0031] According to embodiments of the present application, the support member has an annular shape or a tubular shape.

[0032] According to embodiments of the present application, the support member has a frustoconical inner surface diverging towards the internal volume of the compressor housing. This configuration of the support member makes the introduction and removal of the tubular member and the float element through the axial through passage easy.

[0033] According to an embodiment of the application, the support member is at least partially inserted in the passage opening and sealingly fixed to the passage opening.

[0034] According to an embodiment of the application, the axial through passage and the passage opening are coaxially arranged relative to each other.

[0035] According to an embodiment of the application, the tubular element and the floating element are dimensioned to allow insertion and removal of the tubular element and the floating element through the axial through passage of the support member.

[0036] According to an embodiment of the application, the support member comprises a cylindrical support portion, which is at least partially arranged outside the compressor housing and protrudes in a radial direction away from the compressor housing.

[0037] According to an embodiment of the application, the oil level sensor device comprises a mounting flange, which is fixed to a proximal end portion of the tubular element, the mounting flange comprising a first flange face and a second flange face opposite to the first flange face, the first flange face comprising an annular contact surface, which abuts against an end face of the cylindrical support portion. Advantageously, the end face of the cylindrical support portion and the mounting flange are arranged outside the compressor housing.

[0038] According to an embodiment of the application, the oil level sensor device further comprises a sealing element arranged between the mounting flange and the cylindrical support portion.

[0039] According to an embodiment of the application, the mounting flange comprises an annular recess, which is provided at the end face of the cylindrical support portion and accommodates the sealing element.

[0040] According to an embodiment of the application, the mounting flange is pressed against the end face of the cylindrical support portion by a threaded fixing member, which cooperates with a thread provided on the cylindrical support portion and with the second flange face of the mounting flange. The thread can be provided on an outer circumferential surface of the cylindrical support portion or on an inner surface of a threaded hole emerging in the end face of the cylindrical support portion.

[0041] According to embodiments of the present application, the threaded fixing member comprises a tubular fixing portion having an inner circumferential surface provided with an internal thread configured to cooperate with a thread provided on an outer circumferential surface of the cylindrical support portion, and an annular bearing portion having an annular bearing surface configured to bear against the second flange face of the mounting flange when the threaded fixing member is tightened on the cylindrical support portion.

[0042] According to embodiments of the present application, the threaded fixing member is a threaded nut element.

[0043] According to embodiments of the present application, the oil level sensor device comprises an electrical connector formed on the second flange face of the mounting flange and configured to allow connection of signal leads and / or power supply leads for communication with a controller of the refrigerant compressor or of a refrigeration system comprising the refrigerant compressor.

[0044] According to embodiments of the present application, the tubular element comprises a distal end which is immersed in the oil sump and is closed.

[0045] According to embodiments of the present application, the tubular element comprises a first tubular portion having a first longitudinal axis and a second tubular portion having a second longitudinal axis, the first longitudinal axis of the first tubular portion and the second longitudinal axis of the second tubular portion being arranged at an angle of about 90 degrees.

[0046] According to embodiments of the present application, the first tubular portion is arranged vertically and is at least partially immersed in the oil sump, the first tubular portion being surrounded by the floating element.

[0047] According to embodiments of the present application, the magnetically sensitive sensor is arranged within the first tubular portion.

[0048] According to embodiments of the present application, the second tubular portion is arranged horizontally. Advantageously, the second tubular portion is at least partially arranged inside the support member.

[0049] According to embodiments of the present application, the second tubular portion extends at least partially through the axial through passage of the support member.

[0050] According to embodiments of the present application, the tubular element comprises an arcuate connection portion connecting the first tubular portion and the second tubular portion.

[0051] According to embodiments of the present application, the oil level sensor device comprises an angular indexing means configured to define a predetermined relative angular position of the mounting flange with respect to the support member. Advantageously, the predetermined relative angular position of the mounting flange is defined such that the first tubular portion extends vertically.

[0052] According to embodiments of the present application, the angular indexing means comprises a first flat portion provided on the mounting flange and a second flat portion provided on the support member and configured to cooperate with the cooperating first flat portion in order to define and maintain the predetermined relative angular position, for example during installation of the threaded fixing member.

[0053] According to embodiments of the present application, the floating body has a hollow or porous structure.

[0054] According to embodiments of the present application, the floating body is made of a material having a lower density than the density of the lubricating oil contained in the oil sump.

[0055] According to embodiments of the present application, the floating body is made of a polymeric material, for example made of polymethylpentene. Advantageously, the polymeric material is molded around the magnet element.

[0056] According to embodiments of the present application, the oil level sensor device is configured to provide a low oil level warning signal to the controller if the oil level in the oil sump reaches a predetermined low oil level.

[0057] According to embodiments of the present application, the controller is configured to stop the refrigerant compressor, for example without or with a predetermined delay, if a low oil level warning signal is provided to the controller.

[0058] According to embodiments of the present application, the controller is configured to allow the refrigerant compressor to continue operation if the oil level in the oil sump reaches a predetermined threshold oil level within a predetermined delay time, wherein the predetermined threshold oil level is higher than the predetermined low oil level.

[0059] The oil level sensor device further comprises at least one additional sensor configured to detect a physical property of the oil sump and / or of a gas inside the compressor housing, such as temperature, pressure, moisture content of the lubricating oil, oil viscosity, oil quality, contaminants, etc. Knowledge of such properties can be used to improve the monitoring and protection of the refrigerant compressor. In particular, the controller is further configured to control the operation of the refrigerant compressor based on the physical property detected by the at least one additional sensor

[0060] According to an embodiment of the present application, said at least one additional sensor is arranged inside said tubular element, and in particular inside said first tubular portion. Advantageously, said at least one additional sensor is a temperature sensor configured to detect the oil temperature in said oil sump.

[0061] According to an embodiment of the present application, the refrigerant compressor further comprises a sensor device configured to detect a physical property of said oil sump and / or a physical property of the gas inside said compressor housing, said sensor device comprising a mounting portion fixed to an additional passage opening provided on said compressor housing and a sensing portion removably fixed to said mounting portion and arranged at least partially inside said compressor housing, said sensing portion and said additional passage opening being sized so as to allow said sensing portion to be inserted into and removed from said compressor housing through said additional passage opening.

[0062] According to an embodiment of the present application, said refrigerant compressor is a hermetic scroll compressor.

[0063] The present application also relates to a refrigeration system comprising a refrigerant compressor according to the present application and a system controller configured to control the operation of said refrigerant compressor on the basis of the oil level detected by said oil level sensor device of said refrigerant compressor.

[0064] These and other advantages will become apparent after reading the following description, which is given, by way of non-limiting example, with reference to the enclosed drawings, wherein: BRIEF DESCRIPTION OF DRAWINGS

[0065] The following detailed description of embodiments of the present application will be better understood when read in conjunction with the appended drawings, wherein:

[0066] Figure 1 is a longitudinal sectional view of a refrigerant compressor according to a first embodiment of the present application.

[0067] Figure 2 is a longitudinal sectional view of a refrigerant compressor according to a first embodiment of the present application. Figure 1 is a partial front perspective view of an oil level sensor device of the refrigerant compressor of

[0068] Figure 3 is a partial front perspective view of an oil level sensor device of the refrigerant compressor of Figure 2

[0069] Figure 4 is a partial front perspective view of an oil level sensor device of the refrigerant compressor of Figure 2 is an exploded perspective view of an oil level sensor device of the refrigerant compressor of​

[0070] Figure 5 is Figure 2 a longitudinal sectional view of an oil level sensor device according to the first embodiment of the application.

[0071] Figure 6 is a partial longitudinal sectional view of a refrigerant compressor according to a second embodiment of the application.

[0072] Figure 7 is a partial longitudinal sectional view of a refrigerant compressor according to a third embodiment of the application.

[0073] Figure 8 is a partial longitudinal sectional view of a refrigerant compressor according to a fourth embodiment of the application. DETAILED DESCRIPTION

[0074] Figure 1 A refrigerant compressor 1 occupying a vertical position and in particular a sealed scroll compressor according to a first embodiment of the application is described. The refrigerant compressor 1 can also be a non-sealed scroll compressor.

[0075] The refrigerant compressor 1 comprises a compressor housing 2, such as a hermetic housing, provided with a suction inlet 3 configured to supply the refrigerant compressor 1 with a refrigerant to be compressed and with a discharge outlet 4 configured to discharge the compressed refrigerant. The compressor housing 2 in particular comprises a middle casing 2.1 which is substantially cylindrical, an upper cover 2.2 fixed to an upper end portion of the middle casing 2.1 and a base plate 2.3 fixed to a lower end portion of the middle casing 2.1. Advantageously, the suction inlet 3 is provided on the middle casing 2.1 and the discharge outlet 4 is provided on the upper cover 2.2.

[0076] The refrigerant compressor 1 further comprises a support device 5 fixed to the compressor housing 2 and a compression unit 6 provided inside the compressor housing 2 and supported by the support device 5. The compression unit 6 is configured to compress the refrigerant supplied by the suction inlet 3. The compression unit 6 comprises a fixed scroll 7 which is fixed with respect to the compressor housing 2 and an orbiting scroll 8 supported by a thrust bearing surface 9 provided on the support device 5 and in slidable contact with the thrust bearing surface 9.

[0077] Furthermore, the refrigerant compressor 1 comprises a drive shaft 11 extending vertically and configured to drive the orbiting scroll 8 in an orbiting motion and an electric drive motor 12, which can be for example a variable speed electric drive motor, coupled to the drive shaft 11 and configured to drive said drive shaft 11 in rotation about a rotation axis A.

[0078] The refrigerant compressor 1 further comprises an oil sump 13 arranged at a lower portion of the compressor housing 2 and advantageously defined by the base plate 2.3.

[0079] The refrigerant compressor 1 further comprises an oil level sensor device 14 configured to detect an oil level in the oil sump 13 and a controller 15 configured to control operation of the refrigerant compressor 1, in particular based on the oil level detected by the oil level sensor device 14. According to Figures 1 to 5 The controller 15 is, according to the illustrated embodiment, a compressor controller configured to control operation of only the refrigerant compressor 1. However, according to another embodiment of the present application, the controller 15 can be a system controller subordinated to a refrigeration system comprising the refrigerant compressor 1 and configured to control operation of said refrigeration system, or the controller 15 can be a compressor controller configured to control operation of a plurality of refrigerant compressors including the refrigerant compressor 1.

[0080] As Figures 2 to 5 The oil level sensor device 14 comprises, preferably as illustrated, a tubular element 16 fixed to the compressor housing 2 and arranged at least partially inside the compressor housing 2 and a floating element 17 arranged inside the compressor housing 2, around the tubular element 16, and configured to float on lubricating oil contained in the oil sump 13.

[0081] According to Figures 1 to 5 The tubular element 16 comprises, according to the illustrated embodiment, a first tubular portion 16.1 having a first longitudinal axis, a second tubular portion 16.2 having a second longitudinal axis, and an arcuate connection portion 16.3 connecting the first tubular portion 16.1 to the second tubular portion 16.2. Advantageously, the first longitudinal axis of the first tubular portion 16.1 and the second longitudinal axis of the second tubular portion 16.2 are arranged at an angle of 90 degrees.

[0082] According to Figures 1 to 5 The first tubular portion 16.1 is, according to the illustrated embodiment, arranged vertically and at least partially immersed in the oil sump 13, and the second tubular portion 16.2 is arranged horizontally and in particular extends radially with respect to a longitudinal axis of the refrigerant compressor 1. Advantageously, the first tubular portion 16.1 is surrounded by the floating element 17 and comprises a distal end 161 immersed in the oil sump 13 and closed.

[0083] Advantageously, the floating element 17 is a magnetic floating element and comprises a floating body 18 and a magnet element 19 arranged and for example encapsulated within the floating body 18.

[0084] As Figure 5 As is preferably shown, the floating body 18 comprises a central through passage 21 into which the tubular element 16 extends, and the floating body 18 is slidably mounted with respect to the tubular element 16, and in particular with respect to the first tubular portion 16.1, along a displacement direction D which extends substantially parallel to the longitudinal axis of the refrigerant compressor 1. The floating body 18 can be tubular, for example.

[0085] The floating body 18 can have a hollow or porous structure. Alternatively, the floating body 18 can be made of a material having a lower density than the density of the oil contained in the oil sump 13. The floating body 18 can be made of a polymer material, for example, such as polymethyl pentene, for example. Advantageously, the polymer material can be molded around the magnet element 19. According to another embodiment of the application, however, the floating body 18 can be made of stainless steel, for example.

[0086] The magnet element 19 can comprise a plurality of permanent magnets which are angularly distributed around the central through passage 21 provided on the floating body 18. Alternatively, the magnet element 19 can comprise an annular permanent magnet which is coaxially provided with respect to the central through passage 21.

[0087] The oil level sensor device 14 further comprises a magnetically sensitive sensor 22 which is arranged inside the tubular element 16, and in particular inside the first tubular portion 16.1, and which is configured to be activated by the magnetic field provided by the magnet element 19. The magnetically sensitive sensor 22 can be a Hall sensor or a magnetically operated electrical switch, such as a magnetic reed switch, for example.

[0088] The oil level sensor device 14 further comprises a support member 23, such as a support sleeve, which is fixed and for example welded to a passage opening 24 which is provided on the compressor housing 2, and advantageously on the middle housing 2.1 of the compressor housing 2. The passage opening 24 can be provided on a flat surface portion of the middle housing 2.1, and can be located at a lower end portion of the middle housing 2.1. The support member 23 has an annular or tubular shape, and is at least partially inserted into and sealingly fixed to the passage opening 24.

[0089] The support member 23 comprises an axial through passage 25 which is coaxially arranged with respect to the passage opening 24 and through which the second tubular portion 16.2 extends. The dimensions of the tubular element 16 and of the floating element 17 are defined so as to allow the insertion and removal of the tubular element 16 and of the floating element 17 through the passage opening 24 and through the axial through passage 25 of the support member 23. Advantageously, the support member 23 has a frustoconical inner surface 231 which diverges towards the internal volume of the compressor casing 2.

[0090] The support member 23 further comprises a cylindrical support portion 26 which is arranged outside the compressor casing 2 and projects in a radial direction away from the compressor casing 2. The cylindrical support portion 26 comprises an end face 27 which is arranged outside the compressor casing 2 and an outer circumferential surface 28 which is provided with threads 29. Advantageously, the cylindrical support portion 26 comprises an annular bearing portion 30 which is configured to be supported on an annular seat which is provided on the inner face of the middle casing 2.1 and which surrounds the passage opening 24. Thanks to the provision of such an annular bearing portion 30, the support member 23 can be maintained firmly fixed on the middle casing 2.1 even if the pressure inside the compressor casing 2 is very high and the welding of the support member 23 on the middle casing 2.1 is poor.

[0091] The oil level sensor device 14 further comprises a mounting flange 31 which is fixed to the proximal portion of the tubular element 16. The mounting flange 31 has a flat disc shape and extends coaxially with respect to the second tubular portion 16.2. The mounting flange 31 comprises a first flange face 31.1 and a second flange face 31.2 which is opposite the first flange face 31.1. The first flange face 31.1 comprises in particular an annular contact surface 32 which abuts against the end face 27 of the cylindrical support portion 26.

[0092] Advantageously, the oil level sensor device 14 comprises a sealing element 33, such as an annular seal, which is arranged between the mounting flange 31 and the cylindrical support portion 26 and which is for example housed in an annular groove provided at the end face 27 of the cylindrical support portion 26.

[0093] The mounting flange 31 is pressed against the end face 27 of the cylindrical support portion 26 by means of a threaded fixing member 34, such as a threaded nut element, which cooperates with the threads 29 provided on the outer circumferential surface 28 of the cylindrical support portion 26 and with the second flange face 31.2 of the mounting flange 31. According to a variant not illustrated, the mounting flange 31 is fixed to the cylindrical support portion 26 by means of a welding operation. Figures 1 to 5In the illustrated embodiment, the threaded fixing member 34 comprises a tubular fixing portion having an inner circumferential surface provided with an internal thread configured to cooperate with a thread 29 provided on an outer circumferential surface 28 of the cylindrical support portion 26, and an annular bearing portion having an annular bearing surface configured to bear against a second flange face 31.2 of the mounting flange 31 when the threaded fixing member 34 is tightened on the cylindrical support portion 26. This releasable connection between the mounting flange 31 and the cylindrical support portion 26 can be of the ROTALOCK type.

[0094] According to Figures 1 to 5 In the illustrated embodiment, the oil level sensor device 14 comprises an angular indexing means 35 configured to define a predetermined relative angular position of the mounting flange 31 with respect to the support member 23, so that the first tubular portion 16.1 extends vertically when the mounting flange 31 is fixed to the support element 23. Advantageously, the angular indexing means 35 comprises a first flat portion 36 provided on the mounting flange 31 and a second flat portion 37 provided on the support member 23 and configured to cooperate with the cooperating first flat portion 36 in order to define the predetermined relative angular position.

[0095] Furthermore, the oil level sensor device 14 comprises an electrical connector 38 formed on the second flange face 31.2 of the mounting flange 31 for allowing connection of signal and / or power supply leads for communication with the controller 15 of the refrigerant compressor 1. Advantageously, the electrical connector 38 extends coaxially with respect to the second tubular portion 16.2.

[0096] According to Figures 1 to 5 In the illustrated embodiment, the oil level sensor device 14 is configured to provide a low oil level warning signal to the controller 15 if the oil level in the sump 13 reaches a predetermined low oil level. This predetermined low oil level can be chosen to be about half of the nominal oil capacity of the sump 13 and above a critical oil level. As such, when a low oil level warning signal is output by the oil level sensor device 14, the refrigerant compressor 3 is still likely to be safe to operate for at least a few minutes, and the unit controller can take action to restore lubricating oil in the sump 13 (e.g. by changing the operating sequence of the refrigerant compressors in the manifold).

[0097] According to embodiments of the application, the controller 15 is configured to:

[0098] - if a low oil level warning signal is provided to the controller 15, and if the oil level in the sump 13 does not reach a predetermined threshold oil level within a predetermined delay time after the low oil level warning signal has been provided to the controller 15, then the refrigerant compressor 1 is stopped, wherein the predetermined threshold oil level is higher than the predetermined low oil level;

[0099] - if a low oil level warning signal is provided to the controller 15, and if the oil level in the sump 13 reaches a predetermined threshold oil level within a predetermined delay time after the low oil level warning signal has been provided to the controller 15, then the refrigerant compressor 1 is allowed to continue operation.

[0100] According to another embodiment of the present application, the controller 15 can be configured to stop the refrigerant compressor 1 without any delay time if a low oil level warning signal is provided to the controller 15.

[0101] As Figure 5 The oil level sensor device 14 can also comprise at least one additional sensor 39 configured to detect a physical property of the gas inside the sump 13 or the compressor housing 2, such as temperature, pressure, moisture content of the lubricating oil, oil viscosity, oil quality, contaminants, etc. Knowledge of such properties can be used to improve the monitoring and protection of the refrigerant compressor 1. In particular, the controller 15 can be configured to control the operation of the refrigerant compressor 1 based on the physical property detected by the at least one additional sensor.

[0102] For example, the at least one additional sensor 39 can be an oil temperature sensor 39, for example integrated in the tubular element 16, configured to provide a signal to the controller 15, and the controller 15 can be configured to further control the operation of at least one expansion valve and / or at least one oil heater of a refrigeration system comprising the refrigerant compressor 1 of the present application based on the signal provided by the oil temperature sensor for improving the efficiency of said refrigeration system.

[0103] For example, when the refrigeration system is running, the controller 15 can determine the oil superheat value instead of the suction gas superheat value and apply this value to the control of the expansion valve. The refrigeration system can run with lower oil superheat and reduced suction gas superheat, and thus lower bearing losses and greater heat exchange coefficient in the evaporator, improving the efficiency of the refrigeration system. The refrigeration system can run with no suction gas superheat, and thus with low discharge gas temperature values, and thereby improving the reliability of the refrigeration system under high pressure ratio conditions. However, the refrigeration system cannot run for long times with too low oil superheat, and thus too low oil viscosity, as this means wear of the compressor bearings.

[0104] For example, the oil overheat can be used by the controller 15 to control the sump heater when the refrigeration system is idle. If the oil overheat value is below a predetermined level, the controller 15 can activate the sump heater to increase the oil temperature and prevent refrigerant from condensing in the oil sump 13.

[0105] Figure 6 A refrigerant compressor 1 according to a second embodiment of the present application is disclosed, which differs from the refrigerant compressor shown in Figures 1 to 5 The difference between the refrigerant compressor shown in

[0106] Figure 7 A refrigerant compressor 1 according to a third embodiment of the present application is disclosed, which differs from the refrigerant compressor shown in Figures 1 to 5 The difference between the refrigerant compressor shown in

[0107] According to the embodiment shown in Figure 7 The sensing portion 44 can have a straight shape.

[0108] A temperature sensor or a pressure sensor can for example be arranged inside the sensing portion 44. Such a temperature sensor can be configured to detect the temperature of the lubricating oil contained in the oil sump 13.

[0109] Figure 8 A refrigerant compressor 1 according to a fourth embodiment of the present application is disclosed, which differs from the refrigerant compressor shown in Figures 1 to 5The difference of the shown refrigerant compressor consists substantially in that the oil level sensor device 14 comprises a plurality of tubular elements 16 fixed to the compressor housing 2 and a plurality of floating elements 17 each of which surrounds a respective tubular element 16 and is movably mounted with respect to the respective tubular element 16. According to such an embodiment, the compressor housing 2 comprises a plurality of passage openings 24 each of which is associated with a respective floating element 17 and a respective tubular element 16. According to such an embodiment of the present application, several floating elements can have different minimum and / or maximum detection positions.

[0110] Of course, the present application is not limited to the embodiments described above by way of non-limiting example, but rather encompasses all embodiments thereof.

Claims

1. A refrigerant compressor (1) comprising: - a compressor housing (2); - an oil sump (13) arranged in a lower portion of the compressor housing (2); and - an oil level sensor device (14) configured to detect an oil level in the oil sump (13), the oil level sensor device (14) comprising a tubular element (16) fixed to the compressor housing (2) and arranged at least partially inside the compressor housing, and a floating element (17) surrounding the tubular element (16) and movably mounted with respect to the tubular element (16), the floating element (17) being configured to float on lubricating oil contained in the oil sump (13); wherein the compressor housing (2) comprises a passage opening (24), and the dimensions of the tubular element (16), the dimensions of the floating element (17) and the dimensions of the passage opening (24) are defined to allow the tubular element (16) and the floating element (17) to be inserted into and removed from the compressor housing (2) through the passage opening (24); wherein the oil level sensor device (14) further comprises a support member (23) fixed to the passage opening (24), the support member (23) comprising an axial through passage (25) and being configured to allow the tubular element (16) and the floating element (17) to be inserted and removed through the axial through passage (25), the tubular element (16) being attached to the support member (23); wherein the support member (23) comprises a cylindrical support portion (26) arranged at least partially outside the compressor housing (2) and projecting in a radial direction away from the compressor housing (2); wherein the oil level sensor device (14) comprises a mounting flange (31) fixed to a proximal portion of the tubular element (16), the mounting flange (31) comprising a first flange face (31.1) and a second flange face (31.2) opposite the first flange face (31.1), the first flange face (31.1) comprising an annular contact surface (32) abutting an end face (27) of the cylindrical support portion (26); wherein the mounting flange (31) is pressed against the end face (27) of the cylindrical support portion (26) by a threaded fixing member (34) cooperating with a thread (29) provided on the cylindrical support portion (26) and with the second flange face (31.2) of the mounting flange (31). ​ wherein said oil level sensor device (14) comprises an angular indexing means (35) configured to define a predetermined relative angular position of said mounting flange (31) with respect to said support member (23); and wherein said angular indexing means (35) comprises a first flat portion (36) provided on said mounting flange (31) and a second flat portion (37) provided on said support member (23) and configured to cooperate with the cooperating first flat portion (36) to define and maintain said predetermined relative angular position.

2. The refrigerant compressor (1) of claim 1, wherein, Said floating element (17) comprises a floating body (18) and a magnet element (19) fixed to said floating body (18).

3. The refrigerant compressor (1) of claim 2, wherein, Said floating body (18) is made of a material having a lower density than the density of said lubricating oil contained in said oil sump (13).

4. The refrigerant compressor (1) according to claim 2 or 3, wherein Said magnet element (19) is arranged at least partially within said floating body (18).

5. The refrigerant compressor (1) according to claim 2 or 3, wherein Said oil level sensor device (14) comprises a magnetically sensitive sensor (22) arranged inside said tubular element (16) and configured to be activated by a magnetic field provided by said magnet element (19).

6. The refrigerant compressor (1) of claim 1, wherein, Said passage opening (24) is provided on a mid-shell (2.1) or on a base plate (2.3) of said compressor housing (2).

7. The refrigerant compressor (1) of claim 1, wherein, Said oil level sensor device (14) comprises an electrical connector (38) formed on said second flange face (31.2) of said mounting flange (31) and configured to allow the connection of signal leads and / or power supply leads for communication with a controller (15) of said refrigerant compressor (1) or of a refrigeration system comprising said refrigerant compressor (1).

8. The refrigerant compressor (1) of claim 1, wherein, Said tubular element (16) comprises a distal end (161) which is immersed in said oil sump (13) and is closed.

9. The refrigerant compressor (1) of claim 1, wherein, Said tubular element (16) comprises a first tubular portion (16.1) having a first longitudinal axis and a second tubular portion (16.2) having a second longitudinal axis, said first longitudinal axis of said first tubular portion (16.1) and said second longitudinal axis of said second tubular portion (16.2) being arranged at an angle of about 90 degrees.

10. The refrigerant compressor (1) of claim 9, wherein, Said first tubular portion (16.1) is arranged vertically and is at least partially immersed in said oil sump (13), said first tubular portion (16.1) being surrounded by said floating element (17).

11. The refrigerant compressor (1) according to claim 9 or 10, wherein Said second tubular portion (16.2) is arranged horizontally.

12. The refrigerant compressor (1) of claim 1, wherein, Said oil level sensor device (14) further comprises at least one additional sensor configured to detect physical properties of said oil sump (13) and / or of a gas inside said compressor housing (2).

13. A refrigeration system comprising a refrigerant compressor (1) according to any one of claims 1 to 12 and a system controller configured to control operation of the refrigerant compressor (1) based on an oil level detected by the oil level sensor device (14) of the refrigerant compressor (1).

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