"OIL LEVEL SIGNALLING DEVICE FOR COMPRESSOR AND OIL MANAGEMENT APPARATUS, WITH REMOVABLE DETECTION AND

CONTROL UNIT"

[0001] This invention relates to an oil level signalling device for a compressor; in particular, the invention relates to an oil level signalling device for a compressor of a refrigeration system. According to a further aspect, the invention also relates to an oil level management apparatus for a compressor.

[0002] In a refrigeration system, a compressor is typically used to generate a high-pressure refrigerant gas, subsequently liquefied in a condenser and then once again expanded in a closed circuit to subtract heat from the environment to be cooled.

[0003] The compressor has moving parts that must be lubricated to ensure reliable operation and adequate longevity .

[0004] Lubrication is generally accomplished with an oil that wets the moving parts of the compressor and is collected on the bottom of the compressor crankcase. The oil is then put back into circulation by a pump, or by the same refrigerant liquid circulating circulation in the refrigeration circuit so as to maintain an adequate lubrication of the moving parts. [0005] An adequate level of oil is essential to ensure lubrication of the moving parts of the compressor and an efficient heat exchange. The oil level is generally controlled by an operator through an oil inspection window formed on an oil level detection device mounted on the compressor. In some applications, an oil level control apparatus is used not only to detect the oil level but also to control the quantity of oil in the compressor. If correctly dimensioned and installed, an oil control apparatus protects the compressor from both excessive and low oil levels thus avoiding costly replacements due to poor lubrication. Excessive amounts of oil circulating in a refrigeration system reduce its efficiency and may lead to oil slugging at the intake of the compressor, damaging it.

[0006] In the field of the known art, systems are known for detecting and/or regulating the oil level in the compressor that detect any deficiency or excess of oil in the compressor and regulate the right amount of oil required for correct operation of the moving parts of the compressor .

[0007] Some known devices detect the oil level with optical sensors placed in proximity of a transparent window that faces a detection chamber in which the lubricating oil is present; other devices, instead, use magnetic sensors that detect the position of a magnet, which varies as a function of the oil level in the detection chamber.

[0008] Such systems therefore integrate a mechanical part anchored to the compressor and in communication with the compressor crankcase and an electronic control unit responsible for measuring the oil levels detected by the sensors in the mechanical part.

[0009] However, these oil level signalling devices are susceptible to malfunctions caused by impurities and dirt collected in the lubricating oil during the cycle that compromise the correct detection of the oil level. For example, in the case of optical sensors, such impurities dirty the window through which the optical detection of the oil level is performed, negatively affecting the correct recognition of the amount of oil in the compressor. In the case of magnetic sensors, the impurities accumulate around the magnet and the coupling system between the magnet and the walls of the chamber in which the magnet is immersed, negatively affecting the mobility of the magnet according to the oil level and thus the correct measurement of this level.

[0010] In addition, the electronic control unit is subject to malfunction due to short circuits or electric shocks.

[0011] Unfortunately, in the event of a malfunction it is necessary to replace the entire oil management system. [0012] One of the purposes of this invention is to overcome the drawbacks and limitations of the prior art, reducing management costs related to malfunctions of the oil management systems and avoiding to depressurise the compressor or the entire refrigeration system in case of maintenance of the electronic control unit only.

[0013] According to the invention, this purpose is achieved by an oil level signalling device, by an oil management apparatus and by a detection and control unit according to the accompanying independent claims.

[0014] Preferred embodiments of the invention are defined in the dependent claims.

[0015] The characteristics and advantages of the oil level signalling device, the oil management apparatus and the detection and control unit according to this invention will be apparent from the following description, given by way of non-limiting example, in accordance with the accompanying figures, in which:

[0016] - Figure 1 shows an example of a refrigeration system with an oil level signalling device according to an embodiment of the invention;

[0017] - Figure la shows an example of a refrigeration system with an oil management apparatus according to an embodiment of the invention;

[0018] - Figure 2 shows a perspective view of an oil management apparatus according to an embodiment of this invention;

[0019] - Figure 2a shows a side view of an oil level signalling device according to an embodiment of this invention;

[0020] - Figure 2b shows a sectional view of the oil level signalling device of Figure 2a along the plane A' -A' ;

[0021] - Figure 2c shows a front view of an oil level signalling device according to an embodiment of this invention;

[0022] - Figure 2d shows a sectional view of the oil level signalling device of Figure 3c along the plane B'-B';

[0023] - Figure 3 shows a front view of an oil management apparatus according to an embodiment of this invention;

[0024] - Figure 4 shows a sectional view of the oil management apparatus of Figure 3 along the plane B-B;

[0025] - Figure 5 shows a side view of an oil management apparatus according to an embodiment of this invention;

[0026] - Figure 6 shows a sectional view of the oil management apparatus of Figure 5 along the section plane A-A;

[0027] - Figure 7 is a block diagram of a detection and control unit for an oil level signalling device or for an oil management device according to an embodiment of this invention. [0028] With reference to Figures 1 and la, a refrigeration system 100 comprises at least one compressor 10 having a crankcase (or sump) 11 for the containment of the oil and an inlet 12 connected to a duct 14 that receives the refrigerant gas from an evaporator 50.

[0029] The refrigerant gas is compressed by the compressor 10 and sent to the delivery duct 14 through an outlet 13 of the compressor 10. For some refrigeration systems, the delivery duct 14 carries the compressed refrigerant to an oil separator 20 that separates the oil from the refrigerant .

[0030] The refrigerant gas in the oil separator 20 is then sent towards a condenser 40 of the refrigeration system 100 through a refrigerant outlet 21.

[0031] The oil separator 20 accumulates the oil separated from the refrigerant gas in a tank, which communicates with a duct 23 for the supply of oil to the compressor 10. The duct 23 thus constitutes an oil supply system (or an oil return circuit) for the compressor 10.

[0032] Depending on the complexity of the refrigeration system 100 it is possible to provide more than one compressor and/or more than one oil separator and/or more than one oil tank/reserve.

[0033] According to an aspect of the invention, an oil level signalling device 1 is associated to the compressor (in particular to the crankcase 11 of the compressor suitable to contain the oil and/or the moving parts) to detect the amount of oil in the compressor 10.

[0034] In some embodiments, in addition to the mere detection of the oil level, it is also important to regulate the amount of oil in the compressor crankcase with an oil management apparatus 1' . In this case, an oil management apparatus 1' is associated to both the compressor (in particular to the crankcase 11 of the compressor suitable to contain the oil and/or the moving parts) and to the oil supply system 23, to regulate the amount of oil in the compressor 10. The oil management apparatus 1' in addition to detecting the oil level in the compressor 10 is also suitable to regulate the amount of oil in the compressor 10.

[0035] In accordance with the accompanying figures, the oil level signalling device 1 according to this invention comprises a main body 2, preferably made in a single piece .

[0036] In the main body 2, a detection chamber 4 is formed that is connectable in fluidic communication with the crankcase 11 of the compressor and suitable to receive the lubricating oil at least partially. In addition, this detection chamber 4 communicates with the compressor crankcase through at least one fluidic communication path 420 formed in the main body 2.

[0037] A floating element 6 is enclosed in the detection chamber 4 and is suitable to vary its position as a function of the amount of oil inside the detection chamber 4 and, thus, the oil level in the compressor. This floating element 6 is preferably free from mechanical constraints with the detection chamber. In other words, the floating element 6 is not anchored in any way to the inner walls 41 that define the detection chamber .

[0038] Alternatively, in another embodiment variant, the floating element 6 is constrained to the detection chamber. For example the floating element 6 is constrained by a hinge or a shoe to the inner walls 41 that define the detection chamber, so as to be free to move in relation to the variation of the oil level in the detection chamber.

[0039] Preferably, the floating element 6 has a shape and a size such as to allow free movement along at least one main direction of movement X, for example the direction of gravity or in any case the direction in which the level of the free surface of the oil 8 increases /decreases in the detection chamber 4, so as to be able to move as a function of the variation of level.

[0040] Preferably the floating element 6 has a density such as to allow it to float in the oil, i.e., a density lower than the density of the oil in a given range of environmental conditions, for example between -40 °C and 150 °C and between 0 bar and 120 bar of pressure. Preferably, the density is at least 50% lower with respect to the density of the oil and still more preferably it is approximately equal to 30% of the density of the oil, in conditions of 20 °C and 1 atm.

[0041] In the case of a floating element 6 composed of different materials, this density is to be understood as the density of the entire floating element taking into consideration the volumes occupied by each material that constitutes the floating element.

[0042] Preferably, the floating element 6 comprises a portion made of magnetic material 62, for example a permanent magnet, and a portion made of polymeric material 61 that carries said portion made of magnetic material 62.

[0043] The polymeric material used is for example a thermosetting or thermoplastic plastic material, or a rubber or a foamed plastic material or in any case a polymeric material lightened by means of the creation of a cavity, for example a compact polymeric material, in which a cavity is created in its interior.

[0044] Preferably, the polymeric material used is a composite closed-cell foam comprising an unsaturated carbon polymer; even more preferably, the polymeric material comprises a nitrile rubber, also known by the acronym NBR.

[0045] "Closed-cell" means that the material has a structure of closed bubbles filled with gas. However, an open-cell structure can be used in an embodiment variant of the invention but only if suitably insulated with an external insulating surface suitable to prevent the penetration of the oil in the open cells, without which the floating element would absorb oil and sink to the bottom .

[0046] Preferably, the compound comprises other elements (preferably synthetic polymeric materials, and/or phyllosilicates , and/or phenolic resins, and/or sulphur, and/or carbon) suitable to make the compound solid, compact and cohesive and substantially non-deformable at the operating temperatures and pressures of the oil level signalling device 1.

[0047] Preferably, the portion made of magnetic material 62 is totally embedded in the portion made of polymeric material 61.

[0048] In an embodiment, the portion made of magnetic material 62 is received in a magnet seat 61a formed in the portion of made of polymeric material 61 and preferably positioned substantially in the centre of gravity of the floating element 6.

[0049] For the realisation of the floating element 6, a production method requires making a portion in polymeric material for example by injection moulding of a plastic material wherein the mould already includes the presence of an area destined to form a magnet seat 61a in the moulded piece. Subsequently, the portion made of magnetic material, for example a magnet, is housed in the magnet seat 61a and, finally, the seat 61a is sealed by injection of a further polymeric material 630, for example a synthetic resin or the same polymeric material used to create the portion made of polymeric material of the floating element 6.

[0050] In a variant of the realisation method of the floating element, after the realisation of the portion made of plastic material, the latter is drilled so as to create the magnet seat 61a.

[0051] In a further variant embodiment, the portion made of magnetic material is inserted into the mould and over- moulded in the portion made of polymeric material during the step of moulding the portion made of polymeric material, so that the portion made of magnetic material is at least partially (or completely) incorporated into the polymeric material. In the case in which the portion made of magnetic material 62 is partially incorporated, the seat 61a is sealed by injection of further polymeric material 630 as previously described.

[0052] In a preferred embodiment, the floating element 6 has an oblong shape extending mainly along a given longitudinal direction Y. On the outer surface 63 that surrounds the floating element 6, at least one protuberance 64a is formed that projects towards the outside of the floating element 6. Such a protuberance or such a plurality of protuberances 64a, 64b, 64c, 64d are suitable to maintain a defined distance between the inner walls 41 of the detection chamber 4 and the outer surface 63 of the floating element 6. This allows limiting the contact surface between the floating element and the walls of the detection chamber, so as to avoid the adhesion of the outer surface 63 with these inner walls 41, which would lead to an erroneous reading of the oil level. In other words, the protuberances 64a, 64b, 64c, 64d allow avoiding the suction effect that would be created between the outer surface of the floating element 6 and the inner walls 41 of the detection chamber 4, due to the oil film interposed between the two, with the consequent blockage of the floating element on the inner walls 41.

[0053] During its movement, the floating element 6 can bump the walls 41 of the detection chamber 4. In this case, the protuberances 64a, 64b, 64c, 64d allow minimising the adhesion (i.e., the contact surface) between the walls 41 and the movable element 6.

[0054] Preferably, the protuberances are annular projections, which surround the floating element 6. Preferably these protuberances are triangular in section as shown in Figures 2b, 2d, 4 and 6.

[0055] Thanks to the presence of the protuberances, during the movement of the floating element 6, only the upper ends of the annular projections may possibly come in contact with the walls 41 of the detection chamber, drastically reducing the adhesion surface between the floating element 6 and the inner walls 41 of the detection chamber 4.

[0056] In an embodiment, the floating element 6 has a parallelepiped shape, preferably with rounded corners and, in further embodiments, this shape can degenerate into a cylinder shape or intermediate shapes with elliptical section.

[0057] In addition, in a preferred embodiment the outer surface 63 has protuberances 64a, 64b, 64c, 64d arranged on each face that constitutes the outer surface 63. In the case of a substantially parallelepiped shape and its similar shapes, both the side faces of the two base faces have a respective protuberance. [0058] The detection chamber 4 preferably has a shape such as to totally contain the floating element 6 inside it, for example a parallelepiped shape with rounded corners, or, in other words, a shape in which the cross section has a stadium or hippodrome shape.

[0059] In an embodiment, the detection chamber 4 extends mainly along a main chamber direction Z, inclined with respect to the oil inlet-outlet direction K, preferably substantially perpendicular to this oil inlet-outlet direction K.

[0060] In addition, the main chamber direction Z is preferably parallel to the longitudinal direction Y perpendicular to the direction X along which the level of the free surface of the oil 8 in the detection chamber 4 increases/decreases.

[0061] Preferably, between the floating element 6 and the walls 41 that define the detection chamber 4, a space 45 is defined sufficient to ensure small free movements of the floating element 6 (of the order of a few millimetres, for example from 1 to 10 mm) and of the lubricating oil in which it is immersed.

[0062] Furthermore, this space 45 has dimensions such as to prevent the floating element from rotating around its main longitudinal axis Y until it reaches a position rotated through 180° with respect to a reference operating position. In other words, the space has dimensions such as not to enable a rotation of 180° (upside-down) of the floating element 6 around its longitudinal axis Y in order to avoid excessive inclination/inversion of the magnetic axis of the portion made of magnetic material inside it.

[0063] Preferably, this space 45 has a shape such to allow the translation of the floating element 6 substantially only in the vertical direction X (the direction of the force of gravity) , while the translation in the other two directions of the space is less than the translation along the vertical direction X, for example about 5 mm of translation in the vertical direction X compared to about one millimetre in the other perpendicular directions.

[0064] For example, the internal transverse dimension of the detection chamber 4, measured along the transverse direction W perpendicular to the longitudinal direction Y and to the vertical direction X (direction of the force of gravity) is greater than the transverse dimension of the floating element 6 measured along the same transverse direction W. This transverse dimension of the floating element 6 is for example measured as the distance between the most extreme points along the transversal direction W of each protuberance 64a or 64b.

[0065] For example, the internal transverse dimension of the detection chamber 4, measured along the vertical direction X, perpendicular to the longitudinal direction Y and to the transversal direction W, is greater than the vertical dimension of the floating element 6 measured along the same vertical direction X. This vertical dimension of the floating element 6 is for example measured as the distance between the most extreme points along the vertical direction X of each protuberance 64a or 64b.

[0066] For example, the internal longitudinal dimension of the detection chamber 41, measured along the longitudinal direction Y, perpendicular to the vertical direction X and to the transversal direction W, is greater than the longitudinal dimension of the floating element 6 measured along the same longitudinal direction X. This longitudinal dimension Y is for example measured as the distance between the most extreme points along the longitudinal direction Y of each protuberance 64c or 64d.

[0067] Preferably, on a left vertical wall 41a of the chamber is formed at least one oil inlet opening 42. Preferably, also, two oil inlet openings 42 and 43 are formed, for example arranged one above the other along the main movement direction X. The oil inlet opening (s) allow (s) the fluidic communication of the detection chamber 4 with the crankcase of the compressor 10, through a suitable fluidic communication path, for example through channels formed in the main body 2. Annularly to such a fluidic communication path 420 a flange 37 extends for the mechanical coupling of the oil level signalling device 1 with the compressor 10. Preferably, such a fluidic communication path comprises a first channel 42a and a second channel 43a, which extend along the respective main directions Wl and W2 separate from, and parallel to, each other.

[0068] It follows that, depending on the orientation of the oil level signalling device 1 with respect to the compressor and depending on the amount of oil in the crankcase of the compressor, the oil enters and exits into/from the detection chamber through the oil inlet opening 42 or the oil inlet opening 43 or both.

[0069] Preferably, between the detection chamber 4 and the crankcase 11 of the compressor, at least one filter chamber is interposed for filtering impurities from the oil. For example, in proximity of each oil inlet opening 42, 43 a respective filter seat 42', 43' is formed suitable to accommodate a respective filter chamber 42' ',43''.

[0070] In an embodiment, on the side opposite the left vertical wall 41a, the detection chamber 4 communicates with a further inspection chamber 9 through an inspection opening 44 formed on a right vertical wall 41b, opposite the left vertical wall 41a. The inspection chamber 44 is sealingly closed by a plug 91, preferably coupled to the inspection chamber 9 by threading. The plug 91 is preferably provided with an inspection wall 92 made of a transparent material that allows visual inspection of the oil level by an operator.

[0071] The oil level signalling device 1 according to this invention also comprises a detection and control unit 7, suitable to detect a position of the floating element 6 and to generate an oil level signal as a function of the position of the floating element 6. This oil level signal is for example an electrical control signal, an indicator light signal or an acoustic signal.

[0072] Preferably, the detection and control unit 7 comprises a magnetic field sensor, for example a Hall- effect sensor able to detect the position of the portion made of magnetic material of the floating element 6.

[0073] The detection and control unit 7 is removably anchored to the main body 2 in the vicinity of the detection chamber 4.

[0074] In particular, the detection and control unit 7 is externally anchored to the main body and is removable from the main body 2 without having to remove the main body from the compressor 10 (or from the crankcase of the compressor) when this main body 2 is operatively connected to the pressurised compressor.

[0075] "Externally" to the main body means that the detection and control unit 7 is anchored on the outer surface 22 of the main body, i.e., on the surface that faces the outside environment and not in contact with the lubricating oil or the refrigerant liquid.

[0076] In other words, the detection and control unit 7 is removable from the main body without having to depressurise the detection chamber and/or the compressor and/or the refrigeration system.

[0077] Preferably, the detection and control unit 7 is anchored only externally to the main body 2, for example is not fluidically connected to the detection chamber 4. Moreover, still more preferably, the detection and control unit 7 is not fluidically connected even to the oil supply system or the crankcase of the compressor.

[0078] Preferably, this detection and control unit 7 is anchored around the detection chamber 4 by means of two anchoring portions 71,72, externally embracing the main body 2 in the vicinity of the detection chamber 4. The two anchoring portions are for example locked by a joint or by means of a more secure fastening (for example, a screw 73) .

[0079] In addition, preferably, the detection and control unit 7 is entirely closed by an airtight casing 7a (not shown in Figures 2a to 2d) . This casing is for example realised by means of two half-shells 7b, 7c heat-sealed along the coupling line between the two half-shells. In addition, this casing preferably also comprises the two anchoring portions 71,72.

[0080] In an embodiment, the casing 7a is made of plastic material and the two half-shells are welded together by means of a further polymeric material (for example, adhesive or silicone) or by melting the plastic material along the junction line between the two half-shells.

[0081] In an embodiment one or both half-shells 7b, 7c are made of a material comprising polycarbonate and are coupled by fixing means (for example screws) and sealed by a silicone rubber gasket (VMQ) .

[0082] In another embodiment, one or both half-shells 7b, 7c are made of polyvinyl chloride (PVC) and over-moulded at low pressure and low temperature.

[0083] Preferably, on one of the two half-shells 7b is anchored the electronic card 702 (for example on the half-shell made of polycarbonate) . The other half-shell 7c, for example made of PVC, is subsequently over- moulded, for example at low temperature and/or pressure. In this way, there is no need to proceed to a further step of welding or sealing/insulating the half-shells by means of gaskets and/or sealants. [0084] Preferably, the detection and control unit comprises an orientation detection sensor 701, suitable for detecting the orientation of the oil level signalling device 1. This orientation detection sensor 701 is for example an accelerometer (preferably solid state) , suitable for detecting the orientation of the oil level signalling device 1 with respect to the direction of the force of gravity.

[0085] In another embodiment variant, the orientation detection sensor 701 is a rollover sensor (or mechanical tilt switch) or a mercury switch.

[0086] Preferably, the orientation detection sensor detects two main orientation positions substantially inclined with respect to one another by an angle of 180°.

[0087] In an embodiment, the detection and control unit 7 comprises an electronic circuit board 702 on which at least one microprocessor 710 and the magnetic field sensor 703 are housed.

[0088] Figure 7 shows a block diagram of the components constituting the detection and control unit 7 and their functional connections according to an embodiment of the invention .

[0089] Preferably, the unit 7 can comprise one or more of the following components: a magnetic field sensor 703, a voltage sensor 704, a temperature sensor 705, an orientation sensor 706, control switches 707 (for example, an SPDT type relay, preferably with 1 common pole, 1 normally closed and 1 normally open ) , indicator lights 708 (for example LED) and a data storage device 709.

[0090] When the magnetic field sensor detects an oil level below a minimum limit or above a maximum level, the microprocessor 710 generates a corresponding oil signal level (for example, an electric command) to activate one of the signalling peripherals associated with such a command (for example, a control switch 707, or an indicator light 708 or an audible signal) . When the correct oil level is restored, the microprocessor 710 is configured to stop the oil level signal previously generated or it generates a further adequate oil level signal .

[0091] Preferably, if the oil level is not restored within a certain time interval, the control switches 707 are activated to stop the operation of the compressor 10.

[0092] Optionally, the microprocessor is configured so as to activate the control switches 707 also when the voltage and/or temperature levels read by the respective voltage or temperature sensors are outside the working limits .

[0093] Preferably, in the case of relay-type control switches, if the microprocessor detects an error state of the circuit board, for example to a failure of the circuit board or of a component of the apparatus, or if the power supply of the electronic circuit is absent, the normally closed pole of the relay opens and the normally open is closed.

[0094] Preferably, the electronic circuit board is equipped with at least one indicator light 708 (preferably 3 indicator lights) to show the operator the working state of the device 1. These indicator lights 708 are preferably arranged on a side face 7a' of the casing 7a, facing towards the inspection wall 92 (shown for example in Figure 2) .

[0095] Preferably, the detection and control unit 7 is configured to store in the storage device (for example a flash memory physically contained inside the microprocessor itself) a multitude of operating parameters, for example temperature and/or average/minimum/maximum voltage, number of hours of operation, average/minimum/maximum duration and count of oil level, and/or temperature and/or voltage alarms.

[0096] In addition, the unit 7 comprises a data read/write port 711 (for example a port configured for reading via USB or serial protocol) configured to allow an external device to read the values of the aforesaid stored operating parameters. Furthermore, the data read/write port is also suitable for reprogramming the microprocessor .

[0097] As already said, the invention also relates to an oil management apparatus 1' for regulating the oil level in the compressor, for example, shown in one of its embodiments in Figures 2 and 3 to 6. The oil management apparatus 1' comprises the characteristics of the oil level signalling device 1 according to the embodiments described until here. In addition, for the oil management apparatus 1', in the main body 2, there is also formed an oil supply path 3, suitable for placing the oil supply system 23 in fluidic communication with the crankcase 11 of the compressor 10.

[0098] Preferably, the oil supply path 3 comprises an oil inlet mouth 31 connected to the oil supply system 23, from which departs an oil inlet duct 32 that flows into a regulation chamber 33. In the regulation chamber 33, an outlet hole 33a opens in communication with an oil outlet duct 35 that ends with an oil outlet mouth 36 suitable to be associated to the compressor for fluidic communication with the crankcase 11 of the compressor 10. Preferably, annularly around the oil outlet mouth 36, a flange 37 extends for the mechanical coupling of the oil level signalling device 1 with the compressor 10. [0099] Preferably, the oil inlet duct 32 and/or the oil outlet duct 35 is formed in a portion of the main body 2 that extends along an axis parallel to the directions Wl and W2 and arranged between the first channel 42a and the second channel 43a.

[00100] Preferably, in the oil supply path 3, a supply filter 39 is inserted to filter the oil coming from the oil supply system 23.

[00101] In a preferred embodiment, the oil inlet mouth 31 and oil outlet mouth 36 are substantially aligned along an oil input-output direction K, for example so that the centres of the mouths 31 and 36 are coaxial. Furthermore, preferably also the oil inlet duct 32 and the oil outlet duct 35 are coaxial and aligned along the oil inlet-outlet direction K. This oil inlet-outlet direction K is inclined with respect to the force of gravity, for example perpendicular to it. In addition, preferably, the oil inlet-outlet direction K, is inclined with respect to the main chamber direction Z, for example, is substantially perpendicular to the main chamber direction Z.

[00102] Preferably, the oil inlet-outlet direction K is parallel to the main directions Wl and W2 along which develop the channels 42a and 43a.

[00103] In addition, preferably, in the oil management apparatus 1', the detection and control unit 7 is not fluidically connected to the oil supply path 3.

[00104] The oil management apparatus 1' also comprises a regulation device 5, for example a solenoid valve, operating along the oil supply path 3 and suitable to regulate the flow of oil from the oil supply system 23 to crankcase 11 of the compressor 10. The detection and control unit 7 is thus suitable to generate a control signal for the regulation device 5 depending on the position of the floating element 6. In other words, the oil level signal generated by the detection and control unit 7 is processed to generate a control signal for the regulation device 5. In this way, the amount of oil flowing from the oil supply system 23 to the compressor 10 is regulated depending on the actual amount of oil required to reach an adequate and predetermined oil level in the compressor.

[00105] Preferably, the regulation device 5 is electrically connected to the processing and control unit 7 through an electrical connector 55 external to the main body 2 and said regulation device 5 operates in proximity to the regulation chamber 33, for example, to open or close the outlet hole 33a.

[00106] Furthermore, in proximity of the regulation chamber 33, a threaded seat 51 formed in the main body 2 it is suitable to be coupled with the regulation device 5.

[00107] In the case in which the regulation device 5 is a solenoid valve, the outlet hole 33a is for example opened or closed by a rigid sealing element (preferably made of PTFE) fixed to the iron core of the solenoid valve .

[00108] When the magnetic field sensor detects an oil level below a minimum limit, the microprocessor 710 sends an opening command to the regulation device 5 so as to allow the passage of oil from the oil supply system 23 towards the inside of the compressor 10. Once a determined oil level is reached, the microprocessor sends a closure command to the regulation device 5, by stopping the passage of oil towards the compressor crankcase.

[00109] Preferably, the detection and control unit 7 is also configured to store in the storage device the average/minimum/maximum duration and the count of the cycles of the regulation device.

[00110] Preferably, for both the oil level signalling device 1 and the oil management apparatus, if the oil level is not restored within a certain time interval, the control switches 707 are activated to stop the operation of the compressor 10. Optionally, the microprocessor can be configured so as to activate the control switches 707 also when the voltage and/or temperature levels read by the respective voltage or temperature sensors are outside the working limits. Preferably, in the case of relay-type control switches, if the microprocessor detects an error state of the circuit board, for example to a failure of the circuit board or of a component of the apparatus, or if the power supply of the electronic circuit is absent, the normally closed pole of the relay opens and the normally open is closed.

[00111] It is clear that although Figure 2 and Figures

3 to 6 show an embodiment of an oil management apparatus, it is possible to extrapolate in a manner evident to one skilled in the art the characteristics associable to the previously described oil level signalling device (for example represented in Figures 2a to 2d) and vice versa.

[00112] It is also clear for a person skilled in the art that the oil level signalling device, the oil management apparatus and the detection and control unit according to this invention are also suitable to signal and manage the refrigerant level. In other words, the term "oil" should be considered in its most general sense, which also includes a refrigerant liquid.

[00113] Innovatively, thanks to the presence of a removable electronic detection and control unit, the oil level signalling device and the oil management apparatus according to this invention do not have to be replaced in their entirety in the case of a malfunction of only the detection and control unit. This also allows to significantly reducing the operating costs of the refrigeration system.

[00114] Furthermore, advantageously, the possibility of extracting only the processing and control unit, leaving instead the main body connected to the compressor, allows avoiding the costly operations of depressurisation and repressurisation of the system (or even only the compressor) required by the devices of the known art and, consequently, allows reducing the operating downtime of the refrigeration system.

[00115] In addition, the presence of an orientation sensor allows installing the signalling device or the oil management apparatus on the compressor according to a preferred inclination, for example with the detection and control unit facing upward, or according to an inclination rotated 180° around the oil input-output direction K, i.e., with the detection and control unit 7 facing downwards. This flexibility of orientation allows a simpler and more rapid adaptability of the oil level signalling device or the oil management apparatus in a wide variety of refrigeration systems. In fact, thanks to this feature, it is ensured that the indicator lights 708, suitable to signal the state of the device/apparatus (and thus also any abnormalities) are always visible to the operator who performs an inspection.

[00116] Additionally, in an advantageous manner, the presence of a sensor of the variation of the magnetic field allows detecting the oil level in the detection chamber without the need for either a fluidic or electrical connection between the detection chamber 4 and the detection and control unit 7.

[00117] Moreover, the presence of additional sensors such as voltage and temperature sensors and intervention and signalling devices, such as relays or LEDs, allows to improve the timeliness of detection of a malfunction.

[00118] Additionally, thanks to the presence of a totally sealed casing and the absence of fluidic communication between the electronic circuit board and the detection chamber, the longevity of the detection and control unit is greatly improved.

[00119] Also advantageously, the presence of protuberances on the outer surface of the floating element allows minimising the area of adhesion between the floating element and the walls of the chamber, further reducing any risk of blocking due to the presence of impurities and dirt, which are generally responsible for the increase of adhesion or friction between the parts .

[00120] Moreover, also advantageously, the presence of additional filters in communication paths between the detection chamber and the compressor and inside the oil supply path, can further limit the accumulation of impurities .

[00121] Moreover, the floating element, when not constrained to the detection chamber, allows realising a detection chamber with a relatively simple geometry, reducing the complexity of the working and realisation of the oil level signalling device as a whole (for example, the detection chamber with such a simple geometry also allows enclosing the oil supply path and the detection chamber in a single main body) .

[00122] Additionally, in a particularly advantageous manner, the embodiment variant wherein the floating element is free from constraints with the detection chamber (i.e., is free to move in the chamber), the risk of jamming or blocking due to the accumulation of debris and dirt it is reduced, ensuring an improved reliability and longevity of reading of the oil level.

[00123] It is clear that one skilled in the art, in order to meet contingent needs, may make changes to the invention described above, all contained within the scope of protection defined by the following claims.