FR2464461A1 - Fluid level monitoring appts. - has liq. jet issuing from nozzle in tapered chamber which upon meeting rising liq. level alters flow characteristics of jet - Google Patents

Abstract

The fluid level monitoring appts. includes a supply pipe having its inlet end adapted for communication with a source of a liquid under pressure in excess of that of the ambient medium and its outlet end communicating via a nozzle with a shroud adapted to communicate with a vessel containing a fluid, at a level being monitored. The variation of the hydrodynamic condition of the flow of the liquid through the nozzle is registered dependent on the mixing of this liquid flow with the fluid being monitored. The shroud has at least one cross-section of which the ratio of the maximum size of the internal contour to the spacing of this cross-section from the outlet section of the nozzle is less than of 0.35:1. The inlet portion of the shroud is a structure where the internal contour of the cross-section of this portion encompasses the contour of the outlet section of the nozzle.

Description

 The present invention relates to the measurement technique and in particular relates to devices for controlling the level of the fluid in a container.

 The device produced in accordance with the present invention is particularly suitable for automatic control systems for the supply, consumption and distribution of fluids.

 The present invention can also be applied in the food industry as well as in the petrochemical industry, in means of transport for example, in fuel circuits of flying devices as well as in water supply systems and in other similar systems.

 I1 already exists a device for controlling a level of fluid in a container. This device comprises a supply tube, the inlet end of which is suitable for connection with a source of pressurized fluid.

The outlet end of the supply pipe is connected, by means of a nozzle provided with a nozzle suitable for connection, to the fluid container, at a level to be checked.

 In addition, the device is provided with an apparatus, intended to record the variations in the hydrodynamic state of the flow of liquid flowing through the nozzle during the mixing of this flow of liquid with the fluid.

 The nozzle is arranged coaxially with the nozzle and is joined to the latter by its inlet part. The inner surface of the nozzle is a surface of revolution diverging towards its outlet end which is open.

 The known device also includes a control channel formed in the wall of the nozzle, in the vicinity of the nozzle. The outlet of the control channel opens into the internal cavity of the nozzle, while the inlet of this control channel is arranged so that the device is in the working position below the level to be checked of the fluid which acts during the operation of the device, on the jet leaving the nozzle.

 The known device is provided with a pressure tap and a measuring channel intended to supply a fluid pressure signal and to transmit this signal to the pressure tap. The inlet of the measurement channel is located opposite the outlet of the nozzle and coaxially with the nozzle (cf., for example, French patent No. 2,111,973).

 In the absence of fluid in the container at the level to be checked, the jet of liquid flows from the nozzle substantially transversely to the surface of the fluid in the container, according to a laminar flow regime. The jet then passes through the nozzle without touching the walls of the latter and, on leaving this nozzle arrives at the inlet of the measurement channel.

 If the fluid is in the container at the level to be checked, this fluid acts, during its flow in the interior cavity of the nozzle through the control channel, on the jet of liquid emerging from the nozzle. Consequently, the flow regime is changed to a turbulent regime, the jet deviates and emerges from the nozzle by the wall thereof which is located opposite the outlet of the control channel, without penetrating into the inlet of the measuring channel.

 In each of the two cases mentioned, a corresponding pressure signal is formed in the measuring channel. A stronger signal is formed in the absence of fluid at the level to be monitored and a weaker signal is formed in the presence of the fluid at the level to be monitored.

 Since one of the operating conditions of the known device is the laminar regime of the jet of liquid flowing from the nozzle, the device can only operate at low speeds of flow in the nozzle. It is for this reason that the device ensures the formation of pressure signals whose values are relatively small.

 In addition, using the known device, it is difficult to ensure a preservation for a long period (memorization) of the pressure signal formed during the presence of fluid in the container at the level to be checked once the fluid has passed a first time and found itself, for a short time, at the level to be checked.

 In addition, because the operating principle of the known device requires maintaining the jet of liquid leaving the nozzle in a required direction relative to the surface of the fluid, this device is sensitive to movements with acceleration of the elements of the system in which He is used. As a result, this device has been shown to be insufficiently reliable for use in mobile systems. This drawback is due to the fact that, during displacements with acceleration, the surface of the fluid undergoes considerable oscillatory disturbances and the position of this surface relative to the known device, at the place of its mounting, differs appreciably from the prescribed position.

 The invention therefore aims to solve the problem posed by the realization of a device for controlling a level of fluid in a container in which the nozzle is made so as to ensure the control of the level of fluid for values more pressure and velocity of the liquid leaving the nozzle, and therefore for higher values of the pressure signal.

 To solve the problem posed, the invention relates to a device for controlling a level of fluid in a container, in which the inlet end of a supply pipe is suitable for connection with a source of liquid, the pressure of which is higher than the pressure of the ambient medium while its outlet end is connected, by a nozzle to a nozzle suitable for connection, with the fluid container, at the level to be checked, and which comprises a device for the recording the variation of the hydrodynamic being of the stream of liquid flowing through the nozzle as a result of the mixing of this stream of liquid with the fluid. In accordance with the invention, the nozzle comprises at least one cross section for which the ratio between the maximum dimension of the contour of this section and its distance from the outlet of the nozzle is less than 0.35 while the portion or inlet chamber of the nozzle is such that the interior contour of its section tran transverse surrounds the periphery of the nozzle outlet orifice.

 Thanks to this constructive embodiment of the device, the stream of liquid flowing through the nozzle mixes with the fluid, if it is in the container at the level to be checked, widens and isolates the inlet zone from the nozzle. in which a vacuum is formed. The liquid stream then occupies the entire section of the outlet portion of the nozzle.

 If the liquid leaves the nozzle without further widening of the current, this current takes up only a small part of the portion section or outlet chamber of the nozzle. At this time, the pressure in the inlet zone or chamber of this nozzle is equal to the pressure downstream of the nozzle outlet orifice. As a result, it is possible to easily control the hydrodynamic state of the stream of liquid flowing through the nozzle in the presence of the fluid, at the level to be checked, both for high pressure values and for high liquid velocities. coming out of the nozzle.

 The operation of the device is then ensured over a wide range of possible values of pressure and speeds of the liquid leaving the nozzle and at turbulent flow regimes characterized by fairly large values of the speeds.

 It is thus possible to form a pressure signal for higher values.

 At the same time, having formed a vacuum zone in the inlet chamber of the nozzle, a stable variation in the hydrodynamic state of the flow of liquid emerging from the nozzle was ensured. If necessary, it is possible to keep the modified state of the current for an indefinitely long delay even in the absence of a subsequent fluid at the level to be checked.

 It is now possible to keep for a long period (memorize) a pressure signal formed during a single arrival of fluid at the level to be checked and of the presence of this fluid for a short time at the level to be checked.

 I1 is advantageous that the inlet chamber of the nozzle is provided with a tube intended for the communication of its inlet end with the fluid container, at another level to be checked.

 It is advantageous to apply this method when it is necessary to control the variation of the level of a fluid in a container between two levels to be checked, and in this case, the nozzle outlet chamber is placed in communication with the One of the levels of the tubing of the inlet chamber is connected to the other level.

 Thanks to this tubing, it is possible to vary the hydrodynamic state of the current, as a function of the presence of the fluid at a second level to be checked.

 This tubing also makes it possible to carry out the control several times, both of the presence and of the absence of the fluid at the two levels to be controlled.

 I1 is advantageous that the inlet end of the tubing is located at a certain distance from the longitudinal axis of the nozzle.

 This arrangement of the tubing makes it possible to control the variation in the level of the fluid within a required range, which in turn promotes the widening of the possibilities of automatic control systems for the supply, consumption and distribution of fluids in which the proposed device is applied.

 It is recommended to mount a fluid flow limiter in the tubing.

 Having mounted a flow limiter in the tubing, we succeeded in significantly raising the level of the pressure signal. The possibilities of the automatic control of supply and consumption of fluids are further widened using the proposed device.

 It is also advantageous that, in a device in which the recording apparatus comprises a pressure tap provided with a sensitive element and a measurement channel, connected by its inlet end to the pressure tap, in accordance with the invention, the inlet chamber of the nozzle is placed in communication with the inlet end of the measuring channel of the device.

 The connection of the nozzle to the pressure tap ensures the recording of the variation of the hydrodynamic state of the flow of liquid, following the variation of the level of fluid as a function of the variation of the pressure of liquid in the flow.

 It is also advantageous for the inlet chamber of the nozzle to be placed in communication with the inlet end of the measuring channel of the device, by means of a supply pipe and the nozzle.

 Thanks to this connection of the inlet chamber with the measurement channel, via the nozzle, the variation of the hydrodynamic state of the liquid stream is recorded as a function of the variation of the positive excess pressure. liquid pressure upstream of the nozzle.

 I1 is also advantageous to equip the device with a liquid flow limiter mounted in the supply pipe, between the liquid source and the inlet end of the measuring channel of the device.

 This flow limiter ensures a more abrupt variation of the excess pressure in the measurement channel of the device following the variation of the hydrodynamic state of the liquid stream and, consequently, increases the precision of the control.

 It is recommended to provide, in the device, of which 11 apparatus includes a pressure tap, provided with a sensitive element, and a measurement channel, the outlet end of which is connected to the pressure tap while its end d the inlet faces the outlet of the nozzle and is arranged coaxially with the nozzle, fins arranged in a spiral on the inner wall of the nozzle outlet chamber and intended to communicate a tangential velocity component to the current emerging from the nozzle .

 The helical fins ensure the increase of the total pressure at the periphery of the current and the decrease of the total pressure near the axis of the nozzle. This increases the reliability of controlling the fluid level by means of a greater reduction of the pressure signal at the arrival of the fluid from any level to be controlled.

 It is also advantageous that in a device, in which the apparatus comprises a pressure tap provided with a sensitive element, and a measurement channel, the outlet end of which is placed in communication with the pressure tap while its inlet end faces the outlet of the nozzle and coaxial with the nozzle, in accordance with the invention, the outlet chamber of the nozzle is inclined relative to the longitudinal axis of the nozzle.

 Thanks to this arrangement of the nozzle with respect to the nozzle, an orientation of the current in the presence of fluid is ensured at a level to be controlled, downstream of the outlet of the nozzle in the opposite direction from the inlet end of the measurement channel.

 There is thus obtained an even greater decrease in the pressure signal and an increase in the reliability of the operation of the device.

 It is advantageous that in a device in which the apparatus comprises a pressure tap, provided with a sensitive element and a measurement channel, the outlet end of which is connected to the pressure tap and the end of 'inlet faces the outlet of the nozzle and located at a certain distance from the axis of the nozzle, according to the invention, the outlet chamber of the nozzle is coaxial with the nozzle.

 Thanks to these relative positions of the outlet chamber of the nozzle and of the nozzle, it is possible to obtain an additional signal during the presence of the fluid at the level to be checked, downstream of the outlet chamber of the nozzle under the form of positive excess pressure.

 The device, produced in accordance with the present invention, provides secure control of the fluid level over a wide range of pressure and velocity values of the current flowing from the nozzle because it ensures a high level of signal throughout the range of values. pressures and speeds.

 In addition, the device produced in accordance with the present invention ensures the storage of the signal for the presence of the fluid at the level to be checked downstream of the nozzle for any desired delay, including during the variation of the fluid level, within a required range. of values.

 The device for controlling the level of fluid in a container produced in accordance with the present invention ensures the simultaneous obtaining of several signals both of the presence and of the absence of the fluid downstream of the nozzle and upstream of the tubing connected to a second level.

 At the same time, electrical signals, positive excess pressure signals and vacuum presence signals can be obtained by measuring the static and total pressure of the liquid stream.

 The manufacture of the proposed device is fairly simple and its price is quite low.

Hereinafter, concrete examples of embodiment of the present invention are described with reference to the accompanying drawings, in which
- Fig. 1 schematically shows, in longitudinal section, a device for controlling a level of fluid in a container, according to the invention, in the absence of fluid at the level to be checked
- Fig. 2 is a view similar to FIG. 1, of the device after the fluid has once been at the level to be checked
- Fig. 3 is a view of the same device according to the arrow A in FIG. 1
- Fig. 4 is a schematic view of the proposed device, in section along the line IV-IV of Figure 1
- Fig. 5 schematically shows, in longitudinal section, a device according to the present invention, which is provided with a tube intended to connect it to the fluid container at another level to be checked; the device is mounted in the inclined position relative to the fluid levels; and the fluid is absent at the two levels to be checked
- Fig. 6 shows a similar device according to the present invention in which the tubing used to connect the nozzle to the container at the second level to be checked, is directed upwards and at its inlet end at a certain distance from the longitudinal axis of the nozzle; the fluid being absent at the two levels to be checked
- Fig. 7 shows, in longitudinal section, a device according to the present invention, provided with a fluid flow limiter mounted on a tube, directed downwards, connecting the nozzle to the fluid container at a second level to be checked
- Fig. 8 schematically represents, in longitudinal section, a device according to the present invention, provided with a pressure tap and a measurement channel placed in communication with the inlet chamber of the nozzle; the fluid being present at the second level to be checked
- Fig. 9 shows, in longitudinal section, a device according to the present invention, provided with a measurement channel and a liquid flow limiter, mounted in the supply pipe, the fluid being present at the second level to be checked
- Fig. 10 schematically represents, in longitudinal section, a device according to the present invention, provided with helical fins on the internal face of the nozzle outlet chamber, the fluid being present at the second level to be checked
- Fig. 11 schematically represents, in longitudinal section, a device, in accordance with the present invention, in which the nozzle outlet chamber is inclined relative to the longitudinal axis of the nozzle and the inlet end of the channel measurement is directed to this outlet chamber and arranged coaxially with the nozzle, the fluid being present at the second level to be checked
- Fig. 12 schematically represents, in longitudinal section, a device, in accordance with the present invention, in which the outlet end of the measurement channel is at a certain distance from the axis of the nozzle which is coaxial with the outlet of the nozzle; the fluid being present at the second level to be checked.

 The proposed device is intended for controlling a fluid level in a container B (Fig.l). The device comprises a supply pipe 1 (Fig, 1 and 2) adapted to be connected by its inlet end 1a, to a source of liquid (not shown) whose pressure is greater than the pressure of the ambient medium. The outlet end of the tubing 1 is fixed to a nozzle 2, which is coaxial with it. A nozzle 3 is mounted coaxially with the nozzle 2 and the tubing 1. The tubing 1 is put in communication, via the nozzle 2, with the nozzle 3, which is suitable for communicating with the fluid container B at the level to control CC. The axis of the nozzle 2 coincides with the longitudinal axis of the nozzle 3 and is designated by 0-0.

 The device also includes an apparatus 4 intended to record the variation in the hydrodynamic state of the flow of fluid flowing in the nozzle 2, following the mixing of this flow of liquid with the fluid contained in the container.

 The apparatus 4 comprises an elastic membrane 5 dis placed perpendicular to the longitudinal axis 0-0 of the device, in front of the nozzle 3 coaxial therewith.

 The membrane 5 is intended to cooperate with the stream of liquid flowing in the nozzle 2 after the hydrodynamic state of this stream has been modified following its mixing with the fluid contained in the container B.

 In the membrane 5, an orifice is made perpendicular to the axis 0-0 e-t intended for the passage of the current leaving the nozzle 2.

 On the outer side of the membrane is fixed an electrical resistance 7 supplied by a current source (not shown), intended to record the deformation of the membrane 5 by producing a signal during the variation of its electrical resistance and produced according to n ' no matter what design as long as it suits this purpose. The electrical resistor 7 is connected to a receiver (not shown) of the signal produced by the voltage resistor 7. This receiver can also be made according to any known design suitable for this purpose.

 The nozzle 3 has an inlet chamber 8 (Fig.

1 and 2). The inlet chamber is cylindrical in shape and is intended to ensure the stability of the variation in the hydrodynamic state of the current during the presence of fluid in the container B at the level to be checked C-C, as shown in FIG. 2.

 The nozzle 3 also comprises an outlet chamber 9 produced in the form of a truncated cone and intended to ensure the stability of the variation of the hydrodynamic state of the current during the variation, within wide limits, of the pressures and speeds of the liquid flowing through the nozzle 2.

 The nozzle 3 comprises a neck 10 in the form of a cylindrical tube which connects the chambers 8 and 9. The cross section of the neck 10 has a closed circular contour.

 According to the invention, the ratio between the largest dimension of the interior surface of the cross section of the neck 10 and the distance of this section to the outlet section of the nozzle 2 is less than 0.35.

 This ratio between the dimensions mentioned is necessary to ensure the contact of the stream of liquid leaving the nozzle 2, with the neck 10 over the entire internal surface of its cross section, after mixing this stream with the fluid in the container. B.

 According to the invention, the inlet chamber 8 of the nozzle 3 is produced in such a way that the internal contour of its cross section surrounds the periphery of the outlet orifice of the nozzle 2 which is necessary to form the enclosure interior of the inlet chamber Set separate this enclosure from container B.

 The device comprises a ring 11 to which the device 4 is fixed. This ring 11 is coaxial with the nozzle 3 and is connected to the outlet chamber 9 of this nozzle 3 by means of at least three partitions 12 (FIG. 4). The partitions 12 are arranged regularly on the perimeter of the outlet chamber 9 of the nozzle 3 and of the ring 11. The partition 12 and the ring 11 are in one piece.

The partitions 12 delimit openings 13, intended to put the nozzle 3 and the container in communication
B.

 However, the angle between the 0-0 axis of the device and the surface of the fluid can be changed in a fairly arbitrary manner, if one needs to do so, depending on the conditions of the arrangement in the container. It is necessary to ensure in each position of the device, the possibility of penetration of the fluid inside the nozzle from any level to be checked.

 Thanks to the fact that the nozzle 3 has a cross section in which the ratio between the maximum dimension of the contour and its distance from the outlet orifice of the nozzle 2 is at least 0.35, and that the inlet chamber 8 of the nozzle 3 surrounds the periphery of the outlet orifice of the nozzle 2, by the contour of its cross section, there occurs a reliable isolation of the enclosure of the inlet chamber 8 and of the container B during mixing of the current of liquid flowing through the nozzle 2 with the fluid contained in the container.

This is achieved by the fact that the liquid stream comes into contact with the neck 10 around the entire periphery of its cross section. Consequently, the pressure in the enclosure of the inlet chamber 8 corresponds to the pressure of the liquid stream, which is lower than the pressure in the container B, and the variation of the hydrodynamic state of the liquid stream is of a stable nature, which makes it possible to carry out a safe recording of this variation and, consequently, a control sar of the level which the fluid reached.

 In an alternative embodiment of the device for controlling a fluid level, shown in FIG.

5, the pipe 1 with the nozzle 2, the nozzle 3 and the device 4, in other words, all the elements designated by the references 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12 and 13 are produced according to the design which has just been described above and which is represented in FIGS. 1, 2, 3 and 4.

In the device according to the variant shown in Figure 5, the inlet chamber 8 of the nozzle 3, comprises a tube 14, intended to be connected to the container
B containing fluid, by its inlet end being at a second level to be controlled DD.

 The outlet chamber 9 of the nozzle 3 is suitable for communicating with the first level of fluid to be controlled, C-C, in the container B.

 The fluid levels to be checked C-C and D-D, to which the outlet chamber 9 of the nozzle 3 and the inlet end of the tube 14 are connected, can also be found in different containers (not shown).

If the device is produced according to the variant shown in Figure 5, its axis 0-0 is inclined.
However, the device according to this variant can operate with an axis 0-0 inclined at any angle.

 The tubing 14 is concentric with the tubing 1 and delimits, with the latter, an annular channel 15.

 Four holes 16 are provided in the first front wall of the inlet chamber, in the direction of the current in FIG. 5, and are intended to connect this inlet chamber 8 of the nozzle 3 to the channel 15. The holes 16 are regularly distributed in the front wall of the chamber 8. Because in this embodiment of the device, the current of liquid, circulating through the nozzle 2, can mix with the fluid of the container B arriving in the enclosure of the chamber inlet 8, both through the outlet chamber 9 of the nozzle 3 and through the pipe 14, in other words, both at the CC level and at the DD level, it is possible to control the fluid at these two levels.

 The succession and the value of the signal supplied by the device 4 depend on the succession of the arrival of the fluid to be checked at the levels C-C and D-D.

 In the embodiment of the device for controlling a level of fluid shown in FIG. 6, the tube 1 with its nozzle 2, the nozzle 3 and the device 4, that is to say, all the elements designated by the marks 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 are produced in the manner described above and represented in FIGS. 1, 2, 3 and 4.

 In the device according to the variant shown in FIG. 6, the inlet chamber 8 of the nozzle 3 comprises a tube 17 arranged perpendicular to the longitudinal axis 0-0 of the nozzle 3 and directed upward relative to it. this.

 The tubing 17 is intended to be connected by its inlet end 17a with another level of fluid to be controlled E-E. The inlet end 17a of the pipe 17 is located at a certain distance from the longitudinal axis 0-0 of the nozzle 3.

 The level to be checked EE, of the fluid, with which the inlet end 17a of the tubing 17 is placed in communication during assembly of the device as shown in FIG. 6, is above the level to be checked CC , of the fluid, to which the outlet chamber 9 of the nozzle 3 is connected.

 Because in the intermediate position (between the levels to be checked CC and EE) of the fluid, its entry into the outlet chamber 9 of the nozzle 3 practically does not vary, a certain distance between the levels to be checked, CC and EE, of the fluid in the container B ensures the stability of the hydrodynamic state of the mixed stream of liquid in the outlet chamber 9 of the nozzle 3 during the period during which the fluid level varies between its two values to be checked, CC and EE. This property of the device also appears in the case where the inlet end 17a of the tubing 17 is arranged below the outlet chamber 9 of the nozzle 3 as we will describe.

 In the embodiment of the device for controlling the level of fluid in the container B shown in FIG. 7, the tubing 1 with the nozzle 2, the nozzle 3 and the device 4 c> that is to say, every elements designated by the references 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 17 are produced in the manner just described and which is shown in the figure 6. But the tubing 17 has its end 17a directed downwards.

 In the embodiment of the device according to the variant shown in Figure 7, a fluid flow limiter 18 is mounted in the tubing 17 and is intended to increase the variation of the signal produced by the device 4 during the variation of the state hydrodynamics of the flow of fluid flowing through the nozzle 2 following the mixing of this flow with the fluid arriving from container B.

 The fluid flow limiter 18 has the form of a short tube mounted in the inlet end 17a of the tubing 17. The diameter of the internal orifice of this tube is smaller than the inside diameter of the tubing 17.

 The fluid flow limiter 18 can also be made according to another design provided that it suits its purpose.

If the device according to the variant shown in FIG. 7 is produced, the inlet end 17a of the tube 17 is located at a certain distance from the longitudinal axis 0-0 of the nozzle 3. For this purpose, the nozzle 3 is oriented in such a way that the tube 17 is directed vertically downwards so that its inlet end 17a is inside the container B at the level to be checked.
FF.

 It is advantageous to direct the tubing 17 downwards when it is necessary to stop the variation of the hydrodynamic being of the current of liquid circulating through the nozzle 2 during the rise in the level of fluid until the fluid has reached the upper level to check the CC level in this case.

 If the device according to the variant shown in FIG. 7, the inlet end 17a of the tube 17 is located in the same container B as the outlet chamber 9 of the nozzle 3. However, in other cases, the outlet chamber 9 of the nozzle 3 and l the inlet end 17a of the tubing 17 may be arranged in different containers (not shown).

 The flow limiter 18 provides a desired amplification of the signal during the variation of the hydrodynamic state of the flow of liquid because the reduction in the flow of fluid respectively decreases the energy necessary to communicate its speed during mixing with the current of liquid flowing through nozzle 2. This is why the speed of the current increases and, consequently, the signal strengthens.

 In another embodiment of the device, according to the variant illustrated in FIG. 8, all the elements designated by the references 1, 2, 3, 8, 9, 10, 17 and 18 are produced in an identical manner to those described here. above opposite figure 7.

 If the device according to the variant shown in FIG. 8 is produced, it includes a device 4a intended for recording the variation of the hydrodynamic state of the stream of liquid flowing through the nozzle 2 following the mixing of this stream of liquid with container fluid 3.

 The apparatus 4a includes a pressure tap 19 intended to record the variation of the pressure in the internal enclosure of the inlet chamber 8 of the nozzle 3 during the variation of the hydrodynamic state of the liquid stream.

 The pressure tap 19 has a pressure-sensitive element and is made according to any design provided that it is suitable for this purpose.

 The apparatus 4a also includes a measurement channel 20 intended to connect the pressure tap 19 to the pressure source to be measured, that is to say to the inlet chamber 8 of the nozzle 3.

 If the device is produced according to the variant illustrated in FIG. 8, the enclosure of the inlet chamber 8 of the nozzle 3 is placed in communication with the inlet end of the measurement channel 20.

 Having connected the inlet chamber 8 of the nozzle 3 with the inlet end of the measurement channel 20, a simple and safe control of the presence of the fluid is ensured at the two levels to be checked CC and FF, because by using this device design it is possible to realize the latter without using auxiliary power sources or signal conversion means.

 In the embodiment shown in FIG.

9, all the elements designated by the references 1, 2, 3, 8, 9, 10, 17 and 18 are produced according to a design identical to those described above and represented in FIGS. 7 and 8.

 The device produced according to the variant shown in Figure 9, comprises an apparatus 4b for ltenregister ~ ment of the variation in the hydrodynamic state of the current of liquid flowing through the nozzle 2.

 The device 4b comprises a pressure tap 21 ramie of an element sensitive to the variation of the pressure.

The pressure tap 21 is intended to record the variation of the liquid pressure in the pipe 1, following the variation of the hydrodynamic state of the current of liquid circulating through the nozzle 2 during the mixing of this liquid with the fluid, at the level to control CC in container B.

 The pressure tap 21 can be produced according to any design provided that it is suitable for this purpose.

 The apparatus 4b also includes a measurement channel 22 intended to bring the pressure to be measured to the pressure tap 21.

 In the case where the device is produced according to the variant of FIG. 9, the inlet chamber 8 of the nozzle 3 is placed in communication with the inlet end of the measurement channel 22 by means of the tubing. supply 1 and nozzle 2.

 Because the variation of the hydrodynamic state of the liquid stream causes the variation of the speed of its flow through the nozzle 2 and, consequently, the variation of its static pressure in the tube 1 upstream of the nozzle 2, the connection of the inlet chamber 8 of the nozzle 3 and of the inlet end of the measurement channel 22 by means of the tube 1 and the nozzle 2, makes it possible to record the variation of the excess pressure positive simultaneously with the recording of the variation of the pressure in the inlet chamber 8 of the nozzle 3 or independently of it.

 The device, produced in accordance with the variant shown in FIG. 9, also comprises a limiter for the flow of liquid 23, mounted in the supply pipe 1 between the source of liquid and the inlet end of the measurement channel 22. The limiter liquid flow 23 in the form of a short tube. The diameter of the interior orifice of this tube is less than the interior diameter of the tubing 1.

 The liquid flow limiter 23 can be made according to any known design, suitable for this purpose.

 Having mounted the limiter 23 upstream of the inlet end of the measurement channel 22, the dependence of the pressure to be measured has been increased on the hydrodynamic state of the flow of liquid flowing through the nozzle and the dependence of this pressure to be measured on the variation of the source liquid pressure.

 In another alternative embodiment of the device for controlling the level of the fluid shown in FIG. 10, all the elements designated by the references 1, 2, 3, 8, 9, 10, 11, 12, 13, 17 and 18 are similar in design to those shown in Figure 7.

 The device, produced according to the variant shown in FIG. 10, comprises an apparatus 4c for recording the variation in the hydrodynamic state of the stream of liquid flowing through the nozzle 2. The apparatus 4c comprises a pressure tap 24. The pressure tap 24 is intended to record the variation of the total pressure in the stream following the variation of its hydrodynamic state.

The pressure tap 24 is made according to any known design suitable for this purpose. The apparatus 4c also includes a measurement channel 25 intended to bring the current pressure to be measured to the pressure tap 24 to which the channel 25 is connected by its outlet end 25a.

The inlet end 25b of the measurement channel 25 is placed opposite the outlet chamber 9 of the nozzle 3, coaxial with the latter and the nozzle 2 and is fixed to the ring 11 by means of a support 26 executed according to any known design provided that it is suitable for this purpose.

 In the case of execution of the device according to the variant -represented in FIG. 10, the outlet chamber 9 of the nozzle 3 is provided with fins 27, carried by its inner surface. These fins 27 are in one piece with the outlet chamber 9 of the nozzle 3 and arranged in a spiral. The fins 27 are used to print a tangential component of current speed after mixing of the liquid leaving the nozzle 2 with the fluid of the container B. The end portions 27a and 27b of the fins 27 decrease in height towards their ends by meeting to the wall of the outlet chamber 9 of the nozzle 3.

 The fins 27 arranged in a spiral, provide a new distribution of energy of the mixed current so that the total pressure in the measuring channel 25 decreases. Consequently, the pressure drop recorded by the pressure tap 24 increases, which increases the sensitivity and the reliability of the operation of the device.

 In the embodiment of the device in accordance with the variant shown in FIG. 11, the tube 1 and the nozzle 2, the inlet chamber 8, the neck 10, the tube 17 with the limiter 18, the pressure tap 24 and the measurement channel 25 with its inlet and outlet ends, that is to say, all the elements designated by the references 1, 2, 8, 10, 17, 18, 24 and 25 are produced in a similar manner to those illustrated in Figure 10.

 If the device according to the variant shown in FIG. 11 is executed, it comprises a nozzle 28 suitable for communicating with the level to be checked CC, of the fluid, in the container B. The nozzle 28 comprises an inlet chamber 8 and a neck 10 made of a design similar to that of those described above and represented in FIGS. 1, 2, 3, 5, 6, 7, 8, 9 and 10.

The nozzle 28 comprises a conical part 29 and a cylindrical part 30 coaxial, the coricidal axis with the axis 0-O of the device. The parts 29 and 30 of the nozzle 28 are intended to form the mixed stream formed after mixing the stream of liquid, flowing through the nozzle 2, and the fluid of the container B,
The nozzle 28 also has an outlet chamber 31 inclined with respect to the longitudinal axis 0-0. The outlet chamber 31 of the nozzle 28 is intended to modify the direction of the mixed stream before it arrives at the container B.

 The device also includes a support 32, intended to hold the inlet end of the measurement channel opposite the outlet chamber 31 of the nozzle 28.

 By mounting the outlet chamber 31 of the nozzle 28 with a certain inclination relative to the longitudinal axis oO, and at the inlet end of the measurement channel which is coaxial with this axis, the spacing is ensured the direction of the mixed current relative to the input end of the measurement channel 25.

 This is why during the mixing of the jet of liquid leaving the nozzle 2 with the fluid arriving in the internal enclosure of the nozzle 28 from the levels to be checked FF and CC, an even greater reduction in the total pressure is obtained. the measurement channel 25. Consequently, the difference in pressures recorded by the pressure tap 24 crott, which contributes to the increase in the sensitivity and reliability of the operation of the device.

 In the case of the production of the device for controlling the level of fluid in the container B, in accordance with the variant shown in FIG. 12, the tube 1 and its nozzle 2, the nozzle 3 and the tube 17 provided with the limiter 18, that is to say, all the elements designated by the references 1, 2, 3, 8, 9, 10, 17 and 18 are produced in an identical manner to that described above and represented. in Figures 8 and 9.

 The device, produced in accordance with the variant illustrated in FIG. 12, comprises an apparatus 4d for recording the variation in the hydrodynamic state of the stream of liquid flowing through the nozzle 2.

 If the device is produced in accordance with FIG. 12, the device 4d includes a pressure tap 33, provided with a sensitive element intended for recording the total pressure of the current after the mixture of the liquid circulating through the nozzle 2 with the fluid in container B at the level to be checked CC.

 The pressure tap 33 can be produced according to any known design provided that it is suitable for this purpose. The apparatus 4d also includes a measurement channel 34 intended to bring the pressure to be measured to the pressure tap 33e The outlet end 34a of the measurement channel 34 is put in communication with the pressure tap 33 while its end d inlet 34b is arranged opposite the outlet chamber 9 of the nozzle 3 at a certain distance from the axis 0-0 of the nozzle 2.

 If the device is produced in accordance with the variant shown in FIG. 12, the outlet chamber 9 from the nozzle 3 is coaxial with the nozzle 2.

 The measurement channel 34 can comprise several input extratics (not shown) 7, arranged at a certain distance from the axis 0-0. It is possible to join several symmetrically arranged inlet ends.

In this case, the inlet end of the measurement channel 34 is produced in the form of a ring (not shown).

 The inlet end 34b of the measurement channel 34 is fixed to the nozzle 3 by means of a support 35.

 Thanks to the coaxial arrangement of the nozzle 2 and the outlet chamber 9 of the nozzle 3, when the inlet end of the measurement channel is placed at a certain distance from the axis e0, it is possible to check the presence of the fluid according to the presence of a stream of liquid at the periphery of the outlet chamber 9 of the nozzle 3 with a view to obtaining a positive excess pressure signal.

 The device produced in accordance with the variants of the present invention, shown in Figures 1 and 2, operates as follows.

 As the fluid, the level of which must be checked in container B, a liquid is used.

 In order to put the device into action, it is necessary to bring the liquid to the supply pipe, from a source, under a pressure higher than the pressure of the ambient medium in the container B.

 In the absence of fluid at the level to be checked C-C, the jet of liquid flowing through the nozzle 2 tinting the nozzle 2, does not touch the latter and practically does not vary in shape and section diameter. This is why the jet of liquid passes through the orifice 6 of the nembrane 5 without touching it. The membrane 5 does not come into contact at this time with the liquid stream and does not deform, this is why the resistance of the electrical resistance 7 does not vary.

When the fluid arrives at the level to be checked
CC, this fluid mixes with the liquid circulating through the nozzle 2.

 Following mixing, the hydrodynamic state of the liquid stream varies, the jet widens until it comes into contact with the walls of the outlet chamber 9 occupying its section. This is why the current of liquid meets with the membrane 5 and, by cooperating with this membrane, deforms it.

 The deformation of the membrane 5 causes the variation of the electrical resistance of the resistor 7. This variation of the electrical resistance of the resistor 7 is measured using the signal receiver produced by the resistor 7 and, after having measured the resistance electric, the variation of the hydrodynamic state of the liquid current is recorded. The stream of liquid cooperating with the membrane 5 then leaves through the orifice 6 and the openings 13.

 Due to the widening of the jet following the mixing of the stream of liquid from the nozzle 2 and the fluid, until contact with the nozzle 3 over the entire contour of the neck 10, the inner enclosure of the chamber d input 8 is isolated and it establishes in it a lower pressure, equal to the static pressure of the liquid stream. The greater the speed of flow of the liquid through the nozzle 2, the greater the pressure in the inlet chamber 8 of the nozzle 3.

 When the level of the fluid in the container B drops below the level C-C, the hydrodynamic state of the liquid stream does not vary because the low pressure in the inlet chamber 8 does not vary. For this reason, the nature of the interaction of the liquid stream with the membrane 5 does not vary and, consequently, the electrical resistance of the resistor 7 remains invariable. Based on this resistance, it is estimated whether the fluid has reached the level to be controlled C-C.

 A stable variation in the hydrodynamic state of the current takes place when the ratio between the largest dimension of the contour of the neck 10 and the distance of its section at the outlet of the nozzle 2 is less than 0.35. To return the device to the starting position, it is sufficient to interrupt the arrival of the liquid in the supply pipe, from the source of liquid under pressure.

When the device is produced according to the variant shown in FIG. 5, it is put into action in a similar manner to the device produced in accordance with the variant of FIGS. 1 and 2. For this purpose, the pressurized liquid is brought into the tubing. feeding the
In the absence of fluid at the level to be controlled CC, the jet of liquid flowing from the nozzle 2, in a similar manner to the case of the device according to FIGS. 1 and 2, does not change shape and passes through the orifice 6 without touching the membrane 5.

 When the fluid arrives at one of the levels to be checked C-c or D-D, the hydrodynamic state of the liquid stream varies.

 The succession of arrivals of the fluid at the levels to be checked may differ depending on the inclination of the nozzle 3 and the arrangement of the levels to be checked, of the fluid, either in a single container or in different containers.

 During the first arrival of the fluid at the level to be checked C-C, the hydrodynamic state of the liquid stream changes in a similar manner to the variation during the operation of the device produced in accordance with Figures 1 and 2.

 Then. from the first arrival of the fluid at the level to be checked D-D, the fluid enters the channel 15 of the pipe 14 and through the orifices 16 in the interior enclosure of the inlet chamber 8 of the nozzle 3.

 Consequently, the stream of liquid flowing through the nozzle 2 mixes with the fluid and the hydroxynamic state of the stream of liquid varies in a similar manner to the case, described above, of the device produced in accordance with FIGS. 1 and 2.

 The device does not return to its starting position in which the jet of liquid emerging from the nozzle 2 does not touch the walls of the nozzle 3 until after the fluid level has dropped below two levels to be checked CC and DD .

 The variation of the hydrodynamic state of the liquid stream is recorded in a similar manner to that described in the operation of the device produced in accordance with Figures 1 and 2.

 If the device according to the variant shown in FIG. 6 is produced, its activation of the variation in the hydrodynamic state of the liquid stream and the recording of this variation take place in a manner similar to that described, for the device produced according to FIGS. 1, 2, 3, 4 and 5.

 In the absence of fluid at the level to be controlled CC upstream of the outlet chamber 9 of the nozzle 3. the jet of liquid emerging from the nozzle 2 does not touch the nozzle and flows through 11 orifice 6 of the membrane 5 .

When the fluid arrives at the level to be checked
CC, this liquid mixes with the fluid and the variation of the hydrodynamic state of the current is followed by the widening of the jet of liquid.

 The inner enclosure of the inlet chamber 8 of the nozzle 3 is placed in communication with the second level to be checked, E-E, to which the fluid has not yet arrived.

 CT is why the pressure in this enclosure decreases appreciably and, consequently, the signal supplied by the device 4 does not reach its maximum value.

 After the fluid has reached at the level EE the orifice of the inlet end of the pipe 17, the difference between the pressures at the level to be checked and inside the inlet chamber 8 of the nozzle 3 gradually grows.

The signal emitted by the device 4 increases correspondingly.

 When the fluid level drops below the level E-E and the orifice of the inlet end of the tube 17, the signal produced by the device 4 decreases again. The drop in the fluid level below the nozzle 3 causes the variation of the hydrodynamic state of the liquid stream and the corresponding variation of the signal from the device 4.

 If the device is produced in accordance with FIG. 7, putting it into action, varying the hydrodynamic state of the liquid stream and recording this variation takes place in a manner analogous to that described in the operation of the device produced. according to figure 6.

If the device is produced in accordance with the variant shown in FIG. 7, the variation in the hydrodynamic state of the flow of liquid, followed by the widening of this flow, occurs after the arrival of the fluid at the level at control CC. In this case, limiting the flow of fluid sucked in from another level to be checked
FF, through the tube 17 ensures the use of the energy of the stream of liquid flowing through the nozzle 2 for 1 increase of the energy of the mixed stream of liquid. This is why the level of the signal produced by the device 4 rises.

When the level of the fluid drops below the level to be controlled CC, the hydrodynamic state of the stream of liquid flowing through the nozzle 2 and the signal level of the device 4 do not vary until the fluid is absent from the second level to counter FF.

 If the device is produced in accordance with the variant shown in FIG. 8, the actuation of the device, the variation of the hydrodynamic state of the liquid stream and of the signal level of the device recording this variation are done in a similar manner. to that described in the operation of the device produced in accordance with FIG. 7.

 The variation of the hydrodynamic state of the liquid stream is recorded according to the variation of the pressure in the interior enclosure of the inlet chamber 8 of the nozzle 3.

 During the presence of the fluid at the two levels to be checked CC and FF, as well as during the presence of fluid only at the level FF, that is to say at the inlet end of the tube 17 after the level of fluid has dropped compared to the level to be checked CC, the pressure tap 19 registers the presence of vacuum in the interior enclosure of the inlet chamber 8. If the level of the fluid has not reached the level to be checked CC and in the absence of the fluid at the two levels to be checked CC and FF, the pressure tap records the equality of the pressures in the enclosure of the inlet chamber 8 of the nozzle 3 and upstream of the outlet chamber 9 .

 With a device produced according to the variant re presented in FIG. 9, the actuation of the device and the variation of the hydrodynamic state of the flow of liquid following the variation of the level of fluid and the corresponding variation of the pressure in inner enclosure of the inlet chamber 8 of the nozzle 3 are carried out in a similar manner to that described for the device in FIGS. 7 and 8.

 The variation of the hydrodynamic state of the current of liquid circulating through the nozzle 2 causes the variation of the pressure of the liquid in the supply pipe 1 upstream of this nozzle 2.

 In this case, if the flow of the liquid through the nozzle 2 is not followed by its mixing with the fluid and if the jet of liquid does not touch the walls of the nozzle 3, the pressure in the supply manifold, upstream of the nozzle 2, is practically equal to the pressure under which this liquid is brought from the source.

 Following the variation of the hydrodynamic state of the liquid current, due to the arrival of the fluid at the level to be controlled CC, upstream of the outlet chamber 9 of the nozzle 3, followed by the widening of the jet of liquid , the pressure in the supply pipe upstream of the nozzle 2 decreases. The variation in the pressure in the pipe 1 is recorded by the pressure tap 21. The flow limiter 23 then acts as a signal amplifier because it prevents a partial recovery of the pressure recorded by the pressure tap 21.

 If the device is produced in accordance with FIG. 10, the device is put into action, the hydrodynamic state variation of the liquid stream and of the signal level, following the variation of the fluid level, is carried out so similar to that which has just been described for the operation of the device produced in accordance with FIG. 7. In the absence of fluid at the two levels to be checked CC and FF and before arrival of the fluid at the level to be checked CC, downstream of the outlet chamber 9 of the nozzle 3, the jet of liquid flowing through the nozzle 2 practically does not change direction and shape over the entire distance between the outlet orifice of the nozzle 2 and the inlet end of the measurement channel 25. This is why the pressure tap 24 then signals the absence of the fluid by a maximum signal.

When the fluid has reached the level to be checked
CC, the current of liquid flowing through the nozzle 2 mixes, downstream of the outlet chamber 9 of the nozzle 3 with the fluid and the jet of liquid widens. The static pressure and the speed of the current decrease with respect to the pressure and the speed of the current before mixing. This is why the signal from the pressure tap 24 decreases, indicating the variation in the hydrodynamic state of the liquid stream.

 After the mixed stream has expanded to the walls of the outlet chamber 9 of the nozzle 3, this stream begins to cooperate with the fins 27 arranged in a spiral. The current of liquid acquires a tangential component of speed as a result of the interaction with the helical fins 27. The energy of the current of liquid is distributed again and the axial component of the speed of the current in the vicinity of its axis decreases.

 The decrease in the axial component of the speed, in the presence of the fluid, at the level to be controlled F-F, causes the subsequent decrease in the pressure recorded by the pressure tap 24 and the corresponding increase in the sensitivity of the device.

 When the device is produced according to the variant shown in FIG. 11, putting it into action, varying the hydrodynamic state of the liquid stream, recording this variation and varying the level of the signal received by the socket. pressure 24 are carried out in the manner just described for the operation of the device produced in accordance with FIG. 10.

 Before mixing the current of liquid circulating through the nozzle 2 with the fluid at the level to be checked C-C, the pressure tap 24 produces the maximum signal by reacting on the total pressure of the jet of liquid flowing from the nozzle 2.

 After the liquid flowing from the nozzle 2 has been mixed with the fluid, the inlet end of the measurement channel 25 is outside the stream of liquid which is inclined relative to the orifice of the measurement channel 25.

 Consequently, the pressure recorded by the pressure tap 24 decreases and the sensitivity of the device rises respectively.

 In the case of a device according to the variant shown in FIG. 12, the actuation of the device and the variation of the hydrodynamic state of the stream of liquid occur in a similar manner to that described in the operation of the device produced in accordance in Figure 7.

 Before mixing the stream of liquid flowing through nozzle 2 with the fluid at the level to be checked CC, the pressure tap is subjected to the action of a pressure equal to the pressure in container B. The end of the measuring channel 34 does not come into contact with the liquid stream. On arrival of the fluid at the level to be checked C-C, the stream of liquid flowing through the nozzle 2 mixes, downstream of the outlet chamber 9 of the nozzle 3 with the fluid and the jet of liquid widens. The liquid stream then occupies the entire section of the outlet chamber 9 of the nozzle 3. The inlet end of the measurement channel 34 is located in the liquid stream and the pressure tap 33 records the variation in the hydrodynamic state of the liquid stream.

 An experimental model of the device for controlling a fluid level was tested in all aspects. The results have shown a fairly high reliability of its operation despite its fairly simple design.

 The proposed device provides reliable control of the fluid level over a wide range of liquid pressures and, thanks to its universal use, can be applied in various fields of technology.

 Of course, the invention is in no way limited to the embodiments described and shown which have been given only by way of illustrative examples. It is possible to make different modifications provided that they do not go beyond the limits and the scope of the device for controlling the level of the fluid of the invention.

Claims (10)

 1 - Device for controlling a level of fluid in a container, in which the inlet end of a supply nozzle is suitable for connection with a source of liquid, the pressure of which is greater than the pressure of the ambient medium while its outlet end is connected, via a nozzle provided with a nozzle suitable for connection, with the fluid container located at the level to be checked and provided with a device for recording - recording the variation in the hydrodynamic state of the stream of liquid flowing through the nozzle and following the mixing of this stream with the fluid, characterized in that the nozzle has at least one cross section for which the ratio between the maximum dimension of its contour and its distance from the outlet orifice of the nozzle is less than 0.35 while the interior contour of the cross section of the inlet chamber of this nozzle surrounds the periphery of the orifice nozzle outlet.  2 - Device according to claim 1, characterized in that the inlet chamber of the nozzle comprises a tube intended to be connected, by its inlet end, to the fluid container, at the level to be checked.  3 - Device according to claim 2, characterized in that the inlet end of the tube is located at a certain distance from the longitudinal axis of the nozzle.  4 - Device according to claim 2, characterized in that a fluid flow limiter is mounted in the tubing.  5 - Device according to one of claims 1 to 4 wherein the device comprises a pressure tap, provided with a sensitive element, and a measurement channel, characterized in that the inlet chamber of the nozzle is connected at the input end of the measuring channel of the device.  6 - Device according to claim S, characterized in that the inlet chamber of the nozzle is placed in communication with the inlet end of the measuring channel of the device via the supply manifold and the nozzle.  7 - Device according to claim 6, characterized in that it comprises a liquid flow limiter mounted on the supply pipe between the liquid source and the inlet end of the measuring channel of the device.  8 - Device according to one of claims 1 to 7, wherein the apparatus comprises a pressure tap, provided with a sensitive element, and a measurement channel, the outlet end of which is connected to the pressure tap and the inlet end faces the outlet of the nozzle and is arranged coaxially with the nozzle, characterized in that it comprises, on the inside face of the nozzle outlet chamber, fins arranged in a spiral and intended to impart a tangential component of speed to the current emerging from the nozzle.  9 - Device according to one of claims 1 to 8, wherein the device comprises a pressure tap, provided with a pressure-sensitive element, and a measurement channel, the outlet end of which is placed in communication with the pressure tap while its inlet end faces the outlet of the nozzle and disposed coaxially with the nozzle, characterized in that the outlet chamber of the nozzle is inclined relative to the longitudinal axis of the nozzle .  10 - Device according to one of claims 1 to 8, wherein the apparatus comprises a pressure tap, provided with a sensitive element, and a measurement channel, the outlet end of which is connected to the pressure tap and the inlet end faces the outlet of the nozzle and is placed at a certain distance from the axis of the nozzle, characterized in that the outlet chamber of the nozzle is coaxial with the nozzle.