FR3118665A1 - System for measuring the viscosity of an oil in a lubrication circuit of a refrigeration installation - Google Patents

Abstract

An oil viscosity measuring system (1) configured to be mounted in a lubrication circuit of a refrigeration installation, the measuring system (1) comprising: a main body (2) comprising: a vertical portion (20) mounted between the inlet orifice (23) and the outlet orifice (24), a metal ball (3) capable of moving by gravity in the vertical portion (20), a detection device configured to measure a duration of fall of the metal ball (3) between a high point and a low point of the vertical portion (20), a calculation device configured to determine the viscosity of the oil from the measured drop duration, the measuring system (1) comprising a drive device (4) configured to drive the metal ball (3) magnetically in the vertical portion (20) from the low point towards the high point. Abstract Figure: Figure 3

Description

System for measuring the viscosity of an oil in a lubrication circuit of a refrigeration installation

The present invention relates to the field of fluid circuits, in particular in a refrigeration installation and is more particularly aimed at the field of measuring the viscosity of an oil circulating in a refrigeration installation.

In known manner, a refrigeration installation, such as a cold room or a deep freezer, comprises a fluid circuit in which a refrigerant fluid circulates and at least one compressor allowing the circulation of the refrigerant fluid under pressure in the fluid circuit. The refrigerant allows the implementation of the thermodynamic cycle in the refrigeration installation in order to generate cold temperatures. The refrigeration installation also includes a lubrication circuit in which oil circulates to allow the lubrication of the compressor(s).

In practice, during operation, oil can get into the fluid circuit. To eliminate this inconvenience, the refrigeration installation includes an oil/gas separator which separates the oil and the refrigerant in order to reinject the oil into the lubrication circuit.

Similarly, during operation, refrigerant may enter the lubrication circuit. The presence of refrigerant in the lubrication circuit modifies the viscosity of the oil, which is no longer optimal for efficient lubrication of the compressor. When too much refrigerant is present in the oil, its lubricating power is limited, which can lead to compressor malfunctions. In fact, when the refrigeration installation includes a plurality of compressors mounted in series, a change in the viscosity of the oil can cause malfunctions in series on all the compressors of the refrigeration installation.

To eliminate this drawback, it is known to regularly check the viscosity of the oil circulating in a refrigeration installation. For this, a quantity of oil is taken from the refrigeration system and sent to a laboratory to be tested. Such an operation is regularly repeated to allow periodic control of the quality of the oil. Oil viscosity is measured using a measuring device commonly referred to as a viscometer.

As is known, with reference to the , a viscometer 101 comprises a tube 102 and a ball 103, mounted inside the tube 102, the ball 103 being free and subject to gravity. Oil, previously taken from the lubrication circuit of the refrigeration installation, is poured into the tube 102 which is then closed in a sealed manner. An operator then drops the ball 103, which moves in the oil under the effect of gravity. The duration of the fall of the ball 103 from a high point 104 to a low point 105 is measured, which makes it possible to deduce the viscosity of the oil at constant temperature and under atmospheric pressure. The greater the viscosity of the oil, the longer the ball 103 takes to reach the bottom of the tube 102.

In practice, to allow the ball 103 to fall to the bottom of the tube 102, it must be positioned at the top of the tube 102. To do this, the tube 102 must be turned over like an hourglass. Also, the viscometer 101 comprises in known manner a pivot connection L which makes it possible to turn the tube 102 over. Such a turning over requires the intervention of an operator, who manually rotates the tube 102 around the pivot connection L. viscosity of the oil is usually repeated, so as to obtain a viscosity measurement with a reduced bias, which requires manually inverting the tube 102 several times.

Such a viscosity measurement has many drawbacks since it requires sending an oil sample to a laboratory, which represents a waste of time and does not allow a measurement of the viscosity of the oil. in real time. Reactive monitoring of a refrigeration system is therefore not possible.

An immediate solution would be to integrate a viscometer directly into the lubrication circuit of the refrigeration installation. However, the viscometer as known from the prior art operates at constant temperature and under atmospheric pressure. However, a refrigeration installation operates at variable and generally high temperatures and pressures which are not compatible. The mechanical characteristics of viscometers of the prior art do not allow it to operate under such conditions of temperature and pressure. During a viscosity test, the oil sample does not contain any refrigerant following its sampling.

In addition, the viscometer of the prior art requires a manual reversal of the tube to raise the ball to the top of the tube and allow the measurement of the duration of the fall of the ball in the tube, as described above. The integration of a pivoting tube in a refrigeration installation is complex to achieve and requires the ability to isolate a sealed volume and turn it upside down, which has many drawbacks.

To date, there is no device for measuring the viscosity of an oil capable of operating at high temperatures and pressures and which can be mounted in line in a lubrication circuit of a refrigeration installation to allow in-line control. in situ and in real time of the viscosity of the oil.

The invention thus aims to eliminate at least some of these drawbacks by proposing a simple and effective device for measuring the viscosity of an oil, capable of operating whatever the parameters of the installation in terms of temperature and pressure, whatever be the contents of refrigerants whatever the types of refrigerants. The measuring device according to the invention makes it possible in particular to measure the viscosity of the oil circulating in the lubrication circuit instantaneously and in real time, without requiring the sending of a sample to a laboratory.

PRESENTATION OF THE INVENTION

• un corps principal comprenant un orifice d’entrée d’huile configuré pour coopérer avec un orifice de sortie du circuit de lubrification, un orifice de sortie d’huile, configuré pour coopérer avec un orifice d’entrée du circuit de lubrification, et une portion verticale montée entre l’orifice d’entrée et l’orifice de sortie,
• une bille métallique logée dans la portion verticale et apte à se déplacer par gravité dans la portion verticale,
• un dispositif de détection configuré pour mesurer une durée de chute de la bille métallique entre un point haut de la portion verticale et un point bas de la portion verticale,
• un dispositif de calcul configuré pour déterminer la viscosité de l’huile à partir de la durée de chute mesurée,
• le système de mesure comprenant un dispositif d’entrainement configuré pour entrainer la bille métallique de manière magnétique dans la portion verticale depuis le point bas vers le point haut.

The invention relates to a system for measuring the viscosity of an oil configured to be mounted in a lubrication circuit of a refrigeration installation in which the oil circulates, the measuring system comprising:

• a main body comprising an oil inlet configured to cooperate with an outlet of the lubrication circuit, an oil outlet configured to cooperate with an inlet of the lubrication circuit, and a portion vertical mounted between the inlet port and the outlet port,
• a metal ball housed in the vertical portion and able to move by gravity in the vertical portion,
• a detection device configured to measure a fall time of the metal ball between a high point of the vertical portion and a low point of the vertical portion,
• a calculating device configured to determine the viscosity of the oil from the measured drop time,
• the measurement system comprising a drive device configured to drive the metal ball magnetically in the vertical portion from the low point to the high point.

The measurement system according to the invention allows a measurement of the viscosity of the oil contained in the vertical portion by a measurement of the duration of fall of the ball the high point and the low point. Thanks to the drive device, the metal ball can be raised to the highest point, without requiring the reversal of the vertical portion, which makes it possible to connect the main body directly to the lubrication circuit of the refrigeration installation. It is no longer necessary to send an oil sample to a laboratory. The measurement can be carried out in real time, cyclically or by bypassing the lubrication circuit, which makes it possible to intervene more quickly in the event of deterioration of the oil. The measurement system according to the invention also allows more regular and periodic measurement, without extracting oil from the lubrication circuit and therefore without wasting time. It is thus easier and faster to observe a deterioration in the quality of the oil, making it possible to plan a maintenance operation more effectively, for example. The measurement system according to the invention allows an in situ measurement of the viscosity of the oil circulating in the lubrication circuit of the refrigeration installation.

The detection device and the calculation device directly mounted on the measuring system allow rapid measurement directly on the lubrication circuit.

Preferably, the drive device is mounted outside the vertical portion. The drive device can thus drive the metal ball between the low point and the high point, without hindering the movement of the metal ball in the vertical portion. The metal ball can thus fall under the effect of gravity inside the vertical portion, without risking that it comes into contact with the drive device and that it is slowed down in its course. In addition, in the event of failure of the drive device, it is simple and quick to replace it, without the need to fluidically disconnect the complete measuring system from the lubrication circuit.

In a preferred embodiment, the drive device comprises at least one guide rail, and at least one magnetic carriage mounted to move on the guide rail between a low position and a high position.

The drive device allows the magnetic carriage to drive the metal ball in the vertical portion by a simple magnetic connection. The magnetic carriage can be moved between the high position and the low position by sliding along the guide rail, allowing a simple mechanical connection.

Preferably, the guide rail is a threaded rod, allowing by means of a threaded connection to move the magnetic carriage vertically by a simple rotational movement of the guide rail along its own axis.

Preferably, the drive device comprises at least one drive motor configured to move the magnetic carriage on the guide rail. The drive motor advantageously makes it possible to simply drive the guide rail in rotation on itself to drive the magnetic carriage and consequently the metal ball between the low point and the high point.

Preferably, the drive motor is a stepper motor which makes it possible to transform an electrical impulse into an angular movement, making it possible to simply drive the guide rail in rotation.

In one embodiment, the drive device comprises a ball bearing mounted between the guide rail and the main body to allow the guide rail to rotate without causing the appearance of mechanical stresses in the main body.

Preferably, the detection device comprises a first detection member corresponding to the high point in the vertical portion and a second detection member corresponding to the low point in the vertical portion. Two devices for detecting the low point and the high point make it possible to precisely measure the duration of the fall of the metal ball in the vertical portion by detecting with precision when the metal ball is at the high point and when it is at the low point.

Preferably, the second detection member comprises a force sensor and a second magnet configured to move between a high position in which the second magnet is in contact with the metal ball and a low position, in which the second magnet is in contact with the force sensor. The second detection device makes it possible to detect the arrival of the metal ball in the low position when the magnet is no longer in contact with the force sensor, the latter no longer measuring force. Detection is thus effective and instantaneous.

Preferably, the second polarized magnet of the second detection member and the first polarized magnet of the drive device are positioned so as to repel each other when they approach each other, allowing the metal ball to be released so that it goes back to the high point, when the magnetic carriage reaches the low position to cooperate with the metal ball.

Preferably, the drive device comprises a position sensor, able to determine the position of the magnetic carriage on the guide rail, so as to allow the stopping of the drive motor to stop the sliding of the magnetic carriage.

Preferably, the vertical portion comprises a top stop extending inside the vertical portion, the top stop being configured to allow detachment of the metal ball from the top point. The upper stop makes it possible to stop the race of the metal ball by going up in the vertical portion so that it is no longer attracted by the magnetic carriage and can fall into the vertical portion to allow measurement of the viscosity.

Preferably, the main structure comprises in the vertical portion an internal housing allowing the storage of the ball when no measurement is made. The internal housing is in the low position and does not interfere with the introduction and circulation of oil in the vertical portion.

Preferably, the main body is made of stainless steel, allowing the use of a resistant material allowing it to operate even in the presence of oil under high pressure and at high temperature. The circulation of oil under high pressure and at high temperature in the measuring system is thus secured.

Preferably, the metal ball is made of steel, preferably of soft ferromagnetic steel with a very low carbon content in order to be attracted by the magnetic fields of the magnet. Such a metal ball advantageously makes it possible not to keep the magnetism and thus avoids the agglomeration of metal particles on the ball. The duration of the measurement system is thus improved.

Preferably, the main body is configured to withstand a pressure of between 0 and 20 MPa, allowing the introduction of high pressure oil from a lubrication circuit of a refrigeration installation.

Preferably, the main body is configured to withstand a temperature between 0 and 150° C., allowing the introduction of a high temperature oil from a lubrication circuit of a refrigeration installation.

Preferably, the measurement system according to the invention can thus advantageously operate at a high pressure and temperature, allowing it to be installed in any type of refrigeration installation operating at high temperatures and pressures.

Preferably, the measurement system is configured to operate at variable oil temperature and pressure values. It is not necessary for the oil introduced into the measuring device to be at ambient temperature and under atmospheric pressure, as was the case in the viscometer of the prior art.

Preferably, the calculating device is configured to measure the viscosity of the oil from the duration of the fall of the metal ball in the vertical portion, even when the oil is at variable temperatures and pressures, even in presence of variable refrigerant content.

The invention also relates to a refrigeration installation comprising a lubrication circuit and a measurement system as described above, the main body being mechanically and fluidically connected to the lubrication circuit of the refrigeration installation.

The invention also relates to a refrigeration installation comprising at least one refrigerant circuit pressurized by at least one compressor, preferably several, the lubrication circuit supplying the compressor with oil.

• une étape de remplissage de la portion verticale du système de mesure avec l’huile du circuit de lubrification de l’installation frigorifique,
• une étape d’élévation, par le dispositif d’entrainement, de la bille métallique depuis le point bas vers le point haut,
• une étape de chute de la bille métallique dans la portion verticale, et
• une étape de mesure d’une durée de chute de la bille métallique entre le point haut et le point bas, de manière à en déduire la viscosité de l’huile contenue dans la portion verticale.

The invention finally relates to a method for measuring the viscosity of an oil circulating in a lubrication circuit of a refrigeration installation, by means of the measurement system as described above, the method comprising:

• a step of filling the vertical portion of the measuring system with the oil from the lubrication circuit of the refrigeration installation,
• a step of elevation, by the drive device, of the metal ball from the low point to the high point,
• a step of dropping the metal ball into the vertical portion, and
• a step of measuring the duration of the fall of the metal ball between the high point and the low point, so as to deduce therefrom the viscosity of the oil contained in the vertical portion.

PRESENTATION OF FIGURES

The invention will be better understood on reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects. .

There is a schematic representation of a prior art viscometer.

There is a schematic representation of a refrigeration installation comprising a measuring system according to the invention.

There is a schematic representation of the device for measuring the according to one embodiment of the invention.

There is a front view of the device for measuring the , in which the metal ball is in a raised position.

There is a front view of the device for measuring the , in which the metal ball is in a low position.

There is a close-up view of the head portion of the main body of the speed measurement system .

Figures 7 and 8 are close-up views of the foot portion of the main body of the pressure measurement system. , in which the metal ball is respectively free and magnetized to the magnetic carriage.

There is a schematic representation of the steps of a measurement method according to an embodiment of the invention.

It should be noted that the figures expose the invention in detail to implement the invention, said figures can of course be used to better define the invention if necessary.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a system for measuring the viscosity of an oil circulating in a lubrication circuit of a refrigeration installation. The measuring system is mounted directly on the lubrication circuit of the refrigeration installation.

With reference to the , a refrigeration plant IF comprises a refrigerant circuit CF, comprising an inlet branch CFIN and an outlet branch CFOUT, in which refrigerant F is compressed by means of compressors C. The compressors C are also supplied with oil by a CH lubrication circuit in order to lubricate them.

The refrigeration installation IF includes an oil/gas separator S, making it possible to at least partially separate the refrigerant F and the oil which may mix during the operation of the refrigeration installation IF. This oil is reinjected into the compressors C by the lubrication circuit CH. In practice, the oil is not pure in the lubrication circuit CH but contains refrigerant F.

The refrigeration installation IF comprises a measurement system 1 according to the invention allowing the measurement of the viscosity of oil circulating in the lubrication circuit CH. The lubrication circuit CH comprises a bypass comprising an oil inlet I and an oil outlet O connected to the measurement system 1.

In this example, the lubrication circuit CH comprises a first valve V1 between the inlet orifice I and the outlet orifice O which, in the closed position, makes it possible to conduct oil into the measurement system 1. The lubrication circuit CH comprises a second valve V2, between the measurement system 3 and the outlet orifice O, which, in the closed position, allows the oil to be led outside of the measurement system 1. In this example, the valves V1, V2 are controlled in opposition. When the first valve V1 is open and the second valve V2 is closed, the oil does not circulate in the measuring system 1. Conversely, when the first valve V1 is closed and the second valve V2 is open, the oil circulates in the measurement system 1. It goes without saying that other derivation means could be implemented.

Thus, periodic measurements can be carried out in situ, without extracting oil from the CH lubrication circuit.

With reference to the , the measuring system 1 extends longitudinally along an X axis, laterally along a Y axis and vertically along a Z axis, so as to form an orthogonal reference (X, Y, Z). The term "vertical" is defined in this document with respect to the measuring system 1 in use in a lubrication circuit CH, in which the measuring system 1 extends vertically from bottom to top, that is to say from a lower position to a higher position.

The measurement system 1 comprises a main body 2, a metal ball 3 mounted in the main body 2, a device 4 for driving the metal ball 3 in the main body 2, a detection device 5 configured to measure a duration of drop of the metal ball 3 and a calculating device 7 configured to determine the viscosity V of the oil from the measured drop duration.

As shown on the , the main body 2 extends vertically along the Z axis and comprises a foot portion 21, a head portion 22, vertically opposite the foot portion 21, and a vertical portion 20 mounted between the foot portion 21 and the head portion 22. Each of the three portions 20, 21, 22 is preferably machined and the foot 21 and head 22 portions are welded to the vertical portion 20, so as to form a sealed main body 2.

The foot portion 21 comprises an oil inlet 23 circulating in the lubrication circuit CH of the refrigeration installation IF. The inlet 23 is configured to cooperate with the outlet O of the lubrication circuit CH. Preferably, the inlet 23 has a diameter DO of between 16 and 23mm.

The head portion 22 comprises an outlet orifice 24 for oil circulating in the lubrication circuit CH of the refrigeration installation IF. The outlet orifice 24 is configured to cooperate with the inlet orifice I of the lubrication circuit CH. Preferably, the outlet orifice 24 has a diameter DI similar to the diameter DO of the inlet orifice 23, that is to say between 16 and 23mm. The inlet 23 of the foot portion 21 and the outlet 24 of the head portion 22 are configured to fluidically connect the lubrication circuit CH and the measurement system 1.

The vertical portion 20 is mounted between the foot portion 21 and the head portion 22 and extends vertically along the Z axis when the measurement system 1 is in the position of use, that is to say mounted in the CH lubrication circuit.

With reference to the , the vertical portion 20 preferably has the shape of a hollow cylinder, so as to allow the circulation of oil between the inlet 23 and the outlet orifice 24 while guiding the metal ball 3. The portion vertical 20 preferably has an inside diameter D between 16 and 23mm. Such an inside diameter D allows the passage of the metal ball 3 in the vertical portion 20, as will be described in more detail later. The vertical portion 20 also preferably has a radial thickness Ep of between 2 and 4 mm so as to form a robust vertical portion 20, resistant to pressure.

In this example, the foot portion 21 and the head portion 22 respectively comprise a foot support base 25 and a head support base 26, configured to be connected to the training device 4. Each support base 25, 26 preferably extends along the X axis orthogonal to the Z axis, so as to place the drive device 4 parallel to the vertical portion 20, as will be described in more detail below.

Preferably, with reference to the , the head portion 22 comprises an upper stop 27, configured to cooperate with the metal ball 3, as will be described in more detail below. The top stop 27 is preferably in the form of an ergo projecting inside the vertical portion 20 from the head portion 22. The top stop 27 is thus preferably fixed to the head portion 22 of the body main 2 and comprises a free end extending inside the hollow vertical portion 20. In one embodiment, the upper stop 27 has a hollow cylindrical shape so as to allow the insertion inside the vertical portion 20 of a temperature probe making it possible to measure the local temperature of the oil during viscosity measurement.

In a preferred embodiment, as shown in the , the foot portion 21 of the main body 2 comprises an internal housing 28, allowing the storage of the metal ball 3 when no measurement is made, as will be described in more detail later. The internal housing 28 allows the metal ball 3 not to interfere with the introduction of oil into the vertical portion 20.

The main body 2 is preferably made of stainless steel, allowing the use of a robust material, allowing the introduction of oil under high pressure and at high temperature. Such a material thus makes it possible to ensure secure circulation of the oil under pressure and at high temperature in the measuring system 1, without damaging the latter. Preferably, the measuring system 1 is configured to resist a pressure comprised between 0 to 20 MPa Similarly, the measuring system 1 is configured to resist a temperature preferably comprised between 0 and 150°C. The measuring system 1 can thus be fluidically connected directly to the lubrication circuit CH of a refrigeration installation IF.

In other words, the measuring system 1 is configured to receive oil under a pressure of between 0 and 20 MPa and at a temperature of between 0 and 150° C., allowing it to be installed in any type of IF refrigeration installation operating at high and variable temperatures and pressures.

Referring to Figures 4 and 5, the metal ball 3 is housed in the vertical portion 20 of the main body 2 and is able to move by gravity in the vertical portion 20. In other words, the metal ball 3 is free to move inside the hollow tube formed by the vertical portion 20 and is configured to fall, under the effect of gravity, into the vertical portion 20 when it is deliberately placed at the top of the vertical portion 20, i.e. say substantially at the level of the head end portion 20B (as shown in the ). In this example, the metal ball 3 is configured to move in the vertical portion 20 between a high point PH, represented on the , and a low point PB, represented on the . The metal ball 3 is configured to be positioned, in this example, in a state of rest, at the bottom of the vertical portion 20, that is to say in the internal housing 28. The vertical portion 20 and the ball 3 are calibrated.

Preferably, the metal ball 3 is made of low carbon mild steel. Such a material makes it possible to limit the risk that the metal ball 3 will itself acquire magnetization properties on contact with a magnet.

Preferably, the metal ball 3 has a diameter D3 of between 14 and 16 mm allowing the metal ball 3 to move vertically freely in the vertical portion 20.

In the embodiment in which the head portion 22 comprises a top stop 27, the latter is configured to allow the detachment of the metal ball 3 from the top point PH, as will be described in more detail below.

Referring to Figures 3 to 5, the drive device 4 of the measurement system 1 according to the invention is configured to drive the metal ball 3 magnetically in the vertical portion 20 from the low point PB to the high point PH. Preferably, the drive device 4 is mounted outside the vertical portion 20. The movement of the metal ball 3 inside the vertical portion 20 is thus not hindered by the drive device 4.

In a preferred embodiment, the drive device 4 comprises a guide rail 41, a magnetic carriage 42, movably mounted on the guide rail 41 and a drive motor 44 of the guide rail 41.

The guide rail 41 extends longitudinally along the Z axis preferably between the foot support base 25 and the head support base 26 of the main body 2. The guide rail 41 is thus configured to extend vertically , when the measurement system 1 is in the position of use described above, in parallel with the vertical portion 20. Preferably, the guide rail 41 is in the form of a threaded rod extending along the Z axis.

In this example, the guide rail 41 is connected to the foot support base 25 via a ball bearing 47 (shown in the ) so as to allow the guide rail 41 to turn on itself while avoiding any risk of mechanical stresses in the main body 2. It goes without saying that the guide rail 41 could just as well be connected directly to the main body 2.

Referring to Figures 4 and 5, the magnetic carriage 42 is movably mounted on the guide rail 41 between a high position QH (shown on the ), substantially corresponding to the high point PH of the metal ball 3, and a low position QB (shown on the ), corresponding substantially to the low point PB of the metal ball 3. The magnetic carriage 42 is configured to raise the metal ball 3 from the low point PB to the high point PH, as will be described in more detail below. For this, the magnetic carriage 42 preferably comprises a support member 48 comprising an internal thread configured to cooperate with the thread of the guide rail 41. The magnetic carriage 42 is thus capable of sliding vertically along the guide rail 41 during the rotation of the guide rail 41.

The magnetic carriage 42 also includes a first magnet 43, positioned opposite the vertical portion 20 and configured to cooperate with the metal ball 3 by magnetization. In other words, in practice, thanks to the first magnet 43, the metal ball 3 is configured to be attracted by the magnetic carriage 42 and to move along the vertical portion 20 from the low point PB to the high point PH according to the low position QB and high position QH of the magnetic carriage 42. Such operation will be described in more detail later.

The drive motor 44 is configured to allow the movement of the magnetic carriage 42 on the guide rail 41. As such, the drive motor 44 is connected to the guide rail 41 and is configured to drive the latter in rotation, so as to drive the magnetized carriage 42 vertically along the guide rail 41. Preferably, the drive motor 44 is a stepper motor, that is to say a motor configured to make it possible to transform an electric pulse in an angular motion. The drive motor 44 thus makes it possible to drive the guide rail 41 in rotation on itself, that is to say around the axis Z. The operation of such a motor is known and will not be described in more detail in this document. In this example, as shown in the , the drive motor 44 is positioned at the level of the head support base 26, which then comprises a hole for passage of the guide rail 41 to allow the mechanical connection of the latter to the drive motor 44.

In one embodiment, as shown in the , the drive device 4 comprises one or more position sensor(s) 45A, 45B which make it possible to detect the position of the magnetic carriage 42 on the guide rail 41. More specifically, in this example, the drive device 4 comprises a first position sensor 45A, configured to detect when the magnetized carriage 42 is in the low position QB and a second position sensor 45B, configured to detect when the magnetic carriage 42 is in the high position QH. Each position sensor 45A, 45B is preferably in the form of an optical sensor, configured to emit a light beam, for example between two signal emitting and receiving devices. The magnetic carriage 42 then comprises a shutter 46 configured to cut off the light beam emitted by the optical sensor by inserting itself between the two signal transmitting and receiving members. It goes without saying that each position sensor 45A, 45B could just as well be in a different form. Similarly, it goes without saying that the drive device 4 could be free of position sensor 45A, 45B. In this case, the drive device 4 could for example include a device for measuring the count of the steps of the drive motor 44 to know its position on the guide rail 41.

Preferably, with reference to FIGS. 6 to 8, the measurement system 1 comprises a detection device 5 configured to measure a fall time of the metal ball 3 in the vertical portion 20 of the main body 2 between the high point PH and the low point PB.

The detection device 5 preferably comprises a first detection member 51 (shown on the ) and a second detection member 52 (shown in FIGS. 7 and 8). The first detection member 51 allows the detection of the metal ball 3 at the high point PH. The second detection member 52 allows the detection of the metal ball 3 at the low point PB in the vertical portion 20 of the main body 2.

With reference to the , the first detection member 51 is preferably in the form of a force sensor mounted vertically opposite the magnetic carriage 42 under the head portion 22 of the main body 2. In practice, going up, the magnetic carriage 42 is configured to drive the metal ball 3, the latter is configured to be stopped by the upper stop 27 and held by the free end of the upper stop 27, while the magnetic carriage 42 continues its run until come into abutment against the head portion 22 of the main body 2. The magnetic carriage 42 is thus configured to come into contact with the first detection member 51, resulting in the detection of the position of the metal ball 3 at the high point PH. Alternatively, the first detection member 51 can take the form of a magnetic sensor or an optical sensor, for example, configured to be activated when the metal ball 3 is positioned opposite.

The first detection member 51 is configured to detect the position of the metal ball 3 at the high point PH and to send a detection signal to a calculation device 7, which will be described in more detail later.

Referring to Figures 7 and 8, the second detection member 52 comprises a force sensor 53 and a second magnet 54, configured to move between a high position RH (shown on the ), in which the second magnet 54 is in contact with the metal ball 3, and a low position RB (shown on the ), in which the second magnet 54 is in contact with the force sensor 53. In practice, the second detection member 52 is configured to detect the position of the metal ball 3 at the low point PB, when the second magnet 54 is located in the high position RH, that is to say when the second magnet 54 is no longer in contact with the force sensor 53, the latter no longer detecting effort.

The second detection member 52 is configured to detect the position of the metal ball 3 at the low point PB and to send a detection signal to the calculation device 7, as will be described in more detail later.

Preferably, the second polarized magnet 54 is positioned relative to the first polarized magnet 43 of the magnetic carriage 42, so that the two magnets 43, 54 repel each other when they approach each other. Thus, the magnetic carriage 42 frees the magnetic ball 3 from the attraction generated by the second magnet 54 at the low point PB.

As shown on the , the measuring system 1 preferably comprises a device 6 for measuring the pressure and the temperature of the oil contained inside the vertical portion 20. Such a measuring device 6 is configured to send a measuring signal to the computing device 7, the measurement signal comprising information on the temperature value and pressure value of the oil in the vertical portion 20, that is to say, local data. The temperature and pressure measuring device 6 can take the form of a sensor mounted directly inside the vertical portion 20. Alternatively, as described previously, the measuring device 6 can also be present in the form of a probe inserted inside the vertical portion 20 via the hollow cylinder formed by the upper stop 27. It goes without saying that the measuring device 6 could just as well be located directly on the circuit of CH lubrication of the IF refrigeration plant.

As described previously, the measurement system 1 comprises a computing device 7 (shown on the ), configured to determine the viscosity of the oil contained in the vertical portion 20 from the drop time of the metal ball 3 in the vertical portion 20 measured between the high point PH and the low point PB. The computing device 7 is configured to receive from the first detection member 51, at a first instant, a signal for detecting the position of the metal ball 3 at the high point PH, then from the second detection member 52, at a second instant. , a signal for detecting the position of the metal ball 3 at the low point PB. The calculation device 7 is configured to calculate a fall time of the metal ball 3 in the vertical portion 20 between the first instant and the second instant. The calculating device 7 is also configured to receive from the measuring device 6 a pressure value and an oil temperature value. The calculating device 7 is configured to determine the viscosity of the oil from the drop time, the pressure and the temperature.

Preferably again, the calculation device 7 comprises a database comprising a plurality of charts, each chart being configured to make it possible to determine an ideal oil viscosity for a given temperature and a given pressure for the lubrication circuit CH. Preferably, each chart also depends on the nature of the refrigerant F likely to mix with the oil. Such charts make it possible to compare the current viscosity of the oil with an ideal viscosity in order to determine its wear rate precisely for each refrigeration installation.

Contrary to a laboratory measurement in which the pressure and the temperature are predetermined, the calculating device 7 makes it possible to determine a wear rate of the oil from pressure and temperature conditions which are dynamic.

Thanks to the drive device 4 of the measurement system 1 according to the invention, the metal ball 3 can be mounted at the high point PH, to measure the viscosity of the oil in the manner of a ball viscometer, without requiring return the vertical portion 20. In addition, the measurement system 1 according to the invention operating at high and variable temperatures and pressures, it can be mounted in a refrigeration installation IF and connected directly to the lubrication circuit CH. It is no longer necessary to send an oil sample to a laboratory as was the case in the prior art, which represents a significant time saving. The measuring system 1 also allows a more regular measurement, without loss of time, making it possible to provide for example an emptying or a maintenance operation.

There will now be described a method for measuring the viscosity of the oil circulating in a lubrication circuit CH of a refrigeration installation IF, by means of the measurement system 1 as described above, with reference to the .

The oil circulates in the CH lubrication circuit of the IF refrigeration installation at a given pressure and a given temperature. In this example, initially, the oil does not circulate in the measurement system 1. In the measurement system 1, the metal ball 3 is initially at the bottom of the vertical portion 20 at the low point PB, the second magnet 54 is thus initially being in the high position RH, and the magnetic carriage 42 is initially also in the high position QH.

The measurement method firstly comprises a preliminary step of opening so as to allow the circulation of oil in the vertical portion 20 of the longitudinal body 2 via the inlet 23.

The method then comprises a first step E1 of filling the vertical portion 20 of the measuring system 1 with the oil from the lubrication circuit CH of the refrigeration installation IF. When the vertical portion 20 is filled, the positions of the valves V1, V2 are modified, so as to prevent the circulation of oil between the lubrication circuit CH and the measurement system 1 and to form a closed enclosure in the main body 2 In practice, there is permanently oil in the vertical portion 20, this oil is simply renewed during the first stage E1 in order to make it possible to measure the viscosity of the oil which circulates effectively in the circuit of lubrication CH.

The measuring device 6 measures the oil pressure and temperature and sends a message comprising the pressure and temperature values to the calculating device 7.

A signal is then sent to the drive motor 44, controlling the magnetic carriage 42, which descends from the high position QH to the low position QB in a second step E2. When the magnetic carriage 42 arrives at the low position QB, the first position sensor 45A detects it and sends a signal to the drive motor 44 which stops. The magnetic carriage 42 is stopped in the low position QB.

The first magnet 43 of the magnetized carriage 42 having a greater force of attraction than the force of attraction of the second magnet 54, the metal ball 3 is attracted by the first magnet 43, in a step E3. The second magnet 54 then falls back into its low position RB and comes into contact with the force sensor 53. The force sensor 53 then sends information detecting an effort and therefore stalling of the metal ball 3 causing the motor to trip. training 44 to go up. The metal ball 3, attached to the magnetic carriage 42, then rises in an elevation step E4, from the low point PB to the high point PH.

When the metal ball 3 reaches the high point PH, the latter comes into contact with the upper stop 27, the magnetic carriage 42 continues its course, so as to gradually release the attraction of the metal ball 3. When the force of attraction of the first magnet 43 becomes too weak, the metal ball 3 is no longer attracted and begins to fall. Simultaneously, the magnetic carriage 42 comes into contact with the first detection member 51, which then sends a message detecting the vertical position of the metal ball 3 at the high point PH, that is to say a starting signal , at a first instant t1. The method then comprises a step E5 of dropping the metal ball 3 into the vertical portion 20.

When the metal ball 3 reaches the low point PB, it attracts the second magnet 54 which passes from the low position RB to the high position RH and thus detaches from the force sensor 53. The force sensor 53 no longer detects force and a message for detecting the vertical position of the metal ball 3 at the low point PB, that is to say an arrival signal, is sent, at a second instant t2, to the computing device 7, in a step E6.

The method then comprises a measurement step E7, by the calculating device 7, of a fall duration d of the metal ball 3 between the high point PH and the low point PB, from the first instant t1 and from the second instant t2. From the drop duration d, the pressure P and temperature T values, the calculating device 7 determines the current viscosity of the oil.

Preferably, from the pressure P and temperature T values, the calculating device 7 makes it possible to determine, from charts, the ideal viscosity of the oil for the type of oil and the type of refrigerant. F. By comparing the current viscosity of the oil and the ideal viscosity of the oil, the calculating device 7 thus makes it possible to determine the rate of wear of the oil and whether the latter must be replaced. The positions of the valves V1, V2 are modified so as to allow the circulation of oil in the measuring system 1.

The measurement step can be repeated several times in order to obtain consolidated measurements that are free from bias.

Thanks to the invention, the viscosity measurement can be determined quickly and reactively.

Preferably, the viscosity measurement is compared with predetermined thresholds and maintenance actions are implemented if at least one of the thresholds is exceeded.

Claims (12)

System for measuring (1) the viscosity of an oil (F) configured to be mounted in a lubrication circuit (CH) of a refrigeration installation (IF) in which the oil circulates, the measuring system (1) including:

• a main body (2) comprising an oil inlet (23), configured to cooperate with an outlet (O) of the lubrication circuit (CH), an oil outlet (24), configured to cooperate with an inlet orifice (I) of the lubrication circuit (CH), and a vertical portion (20) mounted between the inlet orifice (23) and the outlet orifice (24),
• a metal ball (3) housed in the vertical portion (20) and able to move by gravity in the vertical portion (20),
• a detection device (5) configured to measure a fall time (d) of the metal ball (3) between a high point (PH) of the vertical portion (20) and a low point (PB) of the vertical portion ( 20),
• a calculating device (7) configured to determine the viscosity (V) of the oil from the measured fall time (d),
• the measurement system (1) comprising a drive device (4) configured to drive the metal ball (3) magnetically in the vertical portion (20) from the low point (PB) to the high point (PH).

A measuring system (1) according to claim 1, wherein the drive device (4) is mounted externally to the vertical portion (20). Measuring system (1) according to one of Claims 1 and 2, in which the drive device (4) comprises:

• at least one guide rail (41),
• at least one magnetic carriage (42) movably mounted on the guide rail (41) between a low position (QB) and a high position (QH).

Measuring system (1) according to one of Claims 1 to 3, in which the drive device (4) comprises at least one drive motor (44) configured to move the magnetic carriage (42) relative to the guide rail (41). Measurement system (1) according to one of Claims 1 to 4, in which the detection device (5) comprises a first detection member (51) corresponding to the high point (PH) in the vertical portion (20) and a second detection member (52) corresponding to the low point (PB) in the vertical portion (20). Measurement system (1) according to Claim 5, in which the second detection member (52) comprises a force sensor (53) and a second magnet (54) configured to move between a high position (RH) in which the second magnet (54) is in contact with the metal ball (3) and a low position (RB), in which the second magnet (54) is in contact with the force sensor (53). Measuring system (1) according to one of Claims 1 to 6, in which the vertical portion (20) comprises an upper stop (27) extending inside the vertical portion (20), the upper stop ( 27) being configured to allow detachment of the metal ball (3) from the high point (PH). Measuring system (1) according to one of Claims 1 to 7, in which the main body (2) is made of stainless steel. Measurement system (1) according to one of Claims 1 to 8, in which the main body (2) is configured to withstand a pressure of between 0 and 20 MPa. Measuring system (1) according to one of Claims 1 to 9, in which the main body (2) is configured to withstand a temperature of between 0 and 150°C. Refrigerating installation (IF) comprising a lubrication circuit (CH) and a measuring system (1) according to one of Claims 1 to 10, the main body (2) being mechanically and fluidically connected to the lubrication circuit (CH) of the refrigeration plant (IF). Method for measuring the viscosity (V) of an oil circulating in a lubrication circuit (CH) of a refrigeration installation (IF), by means of the measuring system (1) according to one of Claims 1 to 10, the method comprising:

• a step of filling (E1) of the vertical portion (20) of the measuring system (1) with the oil of the lubrication circuit (CH) of the refrigeration installation (IF),
• a step of elevation (E4), by the drive device (4), of the metal ball (3) from the low point (PB) to the high point (PH),
• a step (E5) of dropping the metal ball (3) into the vertical portion (20), and
• a measurement step (E7) of a fall time (d) of the metal ball (3) between the high point (PH) and the low point (PB), so as to deduce therefrom the viscosity (V) of the oil contained in the vertical portion (20).