阅读说明：本技术 将水溶液喷射到喷射式发动机当中的喷射系统 (Injection system for injecting an aqueous solution into a jet engine ) 是由 弗朗克·道希 斯蒂芬·伦纳德 洛朗·迪埃 皮埃尔·奥兹沃德 于 2019-01-29 设计创作，主要内容包括：本发明涉及一种将水溶液喷射到喷射式发动机当中的喷射系统,该喷射系统包括水溶液的储箱(10)、向所述储箱(10)供应水溶液的供应回路(80)、过滤水溶液的过滤器(100)以及再循环所述水溶液的再循环回路(90)。该喷射系统还包括所述水溶液的再循环回路(90)以及电动阀(130),该电动阀包括连接至储箱的加注槽(82)的第一入口(130a)、连接至再循环回路(90)的第二入口(130b)和连接至供应回路(80)的出口(130c)。所述过滤器(100)被放置在所述供应回路(80)中和/或所述再循环回路(90)中。(The invention relates to an injection system for injecting an aqueous solution into a jet engine, comprising a tank (10) for the aqueous solution, a supply circuit (80) for supplying the tank (10) with the aqueous solution, a filter (100) for filtering the aqueous solution and a recirculation circuit (90) for recirculating the aqueous solution. The injection system also comprises a recirculation circuit (90) of said aqueous solution and an electric valve (130) comprising a first inlet (130a) connected to the filling tank (82) of the tank, a second inlet (130b) connected to the recirculation circuit (90) and an outlet (130c) connected to the supply circuit (80). The filter (100) is placed in the supply circuit (80) and/or in the recirculation circuit (90).)

1. Injection system for injecting an aqueous solution into an injection engine, comprising a tank (10) of aqueous solution, a supply circuit (80) for supplying the tank (10) with aqueous solution, a filter (100) for filtering the aqueous solution and a recirculation circuit (90) for recirculating the aqueous solution, characterized in that it further comprises an electric valve (130), the electric valve (130) comprising a first inlet (130a) connected to a filling tank (82) of the tank, a second inlet (130b) connected to the recirculation circuit (90) and an outlet (130c) connected to the supply circuit (80), and in that the filter (100) is placed in the supply circuit (80) and/or in the recirculation circuit (90).

2. Injection system according to claim 1, further comprising an injection conduit (40) intended to be connected to the intake circuit of the jet engine, the system being configured so that the aqueous solution from the filter (100) passes through the tank (10) before entering the injection conduit (40).

3. Injection system according to claim 1 or 2, wherein the supply circuit (80) comprises a supply pipe (81) connected to the tank (10) and a filling tank (82) of the tank (10) connected to the supply pipe (81).

4. A spraying system according to any one of claims 1 to 3, characterized in that the recirculation circuit (90) comprises an inlet conduit (91) into the tank (10) and an outlet conduit (92) from the tank (10).

5. The spraying system according to any one of claims 1 to 4, characterized in that the aqueous solution is water, in particular tap water or rainwater, and the filter (100) is a de-mineralised and/or contaminated filter.

6. The spray system of claim 5, wherein the demineralizing filter (100) is a demineralizing filter comprising a filter medium composed of an ion exchange resin.

7. The injection system according to claim 5 or 6, characterized in that the filter (100) removing impurities is a fine filter (120).

8. The spraying system according to any one of claims 5 to 7, characterized in that the filter (100) is a removable interchangeable filter.

9. The spray system of claim 8, wherein the filter (100) comprises a washable, reloadable or disposable filter cartridge (110).

10. The spraying system according to any one of claims 1 to 9, characterized in that the filter (100) comprises heating means (102) adapted to heat the aqueous solution.

11. The spraying system according to any one of claims 1 to 10, characterized in that it further comprises a quality sensor (60) of the aqueous solution.

12. A method of purifying an aqueous solution for an injection system according to claim 1 for injecting the aqueous solution into an injection engine, characterized in that the method comprises the steps of:

a. filling the tank (10) with an aqueous solution through a supply circuit (80),

b. -pumping the aqueous solution contained in the tank (10),

c. conveying the aqueous solution pumped in step b) into a recirculation loop (90) of the aqueous solution,

d. filtering the aqueous solution in the supply circuit (80) and/or in the recirculation circuit (90).

13. The method for purifying an aqueous solution according to claim 12, characterized in that it further comprises, after said step d), the steps of:

e. delivering said aqueous solution into said tank (10),

f. the aqueous solution is conveyed into an injection conduit (40) intended to be connected to the intake circuit of the jet engine.

14. A method for evaluating the purity of an aqueous solution for an injection system for injecting the aqueous solution into an injection engine, characterized in that the method comprises the steps of:

a. measuring the physicochemical property sigma of the aqueous solution contained in the tank (10),

b. subjecting the physicochemical property σ measured in said step a)_mWith reference value range [ sigma ]_ref.min，σ_ref.max]Making a comparison of σ in the reference value range_ref.minIs the minimum reference value for the value of the reference,σ_ref.maxis the maximum reference value for the value of the reference,

c. if the physicochemical property σ measured in said step a) is_mIn the reference value range [ sigma ]_ref.min，σ_ref.max]And, the aqueous solution is conveyed to a demineralization filter (100),

d. as long as the physicochemical property σ measured in the step a) is_mIn the reference range [ sigma ]_ref.min，σ_ref.max]Otherwise, repeating said steps a), b) and c),

e. if said physicochemical characteristic σ measured after a predetermined time T_mStill within the reference value range [ sigma ]_ref.min，σ_ref.max]Otherwise, a problem is indicated by the signal S.

15. The evaluation method according to claim 14, wherein the signal S of step e) is an indication of cleaning, reinstalling or replacing the demineralization filter (100).

16. Injection method for injecting an aqueous solution into an injection engine, characterized in that it comprises a step of evaluating the purity of the aqueous solution according to the evaluation method of claim 14, and if said physicochemical property σ measured in said step a) is correct_mIn the reference value range [ sigma ]_ref.min，σ_ref.max]The injection method further comprises the step of delivering the aqueous solution into the injection engine.

Technical Field

The present invention relates generally to the field of liquid storage tanks configured to deliver liquid to internal combustion engines. More particularly, the invention relates to an injection system for injecting a liquid, in particular an aqueous solution, into an injection engine of a vehicle, in particular an automobile.

The invention also relates to an injection method for injecting an aqueous solution into an injection engine.

The invention also relates to a method of purifying an aqueous solution for injection into an injection system in an injection engine.

Finally, the invention relates to a method for evaluating the purity of an aqueous solution for an injection system for injecting the aqueous solution into an injection engine.

Background

It is known to inject water into the intake circuit of an engine. This water mixes with the intake air, allowing to reduce the combustion temperature and to reduce the emissions of pollutants called NOx, and to improve the performance of, for example, gasoline engines by reducing the sensitivity to knocking. Such an injection system is described in patent document FR2801076a 1.

However, in order to ensure good operation of conventional spraying systems, it is known to fill the tank with demineralized water in order to avoid scale clogging the spraying circuit. This is not satisfactory. In practice, there is a limit to filling the tank with demineralized water. A user of a motor vehicle equipped with such a spraying system must carry a demineralized water tank with him on the trip, since about 3 liters of demineralized water must be prepared per 1000 kilometers of travel. Of course, demineralized water can be purchased at a service station, but not available to the user at all service stations.

Disclosure of Invention

The object of the present invention is in particular to overcome the above-mentioned drawbacks. To this end, the subject of the invention is an injection system for injecting an aqueous solution into a jet engine, comprising a tank for the aqueous solution, a supply circuit for supplying the tank with the aqueous solution, a filter for filtering the aqueous solution and a recirculation circuit for recirculating the aqueous solution. According to the invention, the injection system also comprises a recirculation circuit of the aqueous solution and an electric valve comprising a first inlet connected to the filling tank of the tank, a second inlet connected to the recirculation circuit and an outlet connected to the supply circuit in which the filter is placed and/or in which the filter is placed.

Thanks to the invention, it is no longer necessary to fill the tank with demineralized water. In fact, the user of the vehicle can fill the tank with tap water or rain water without the risk of causing scale to the spray circuit, since this water is filtered by the spray system. Tap water is readily available and is available to all gas stations and even outside. Thanks to the invention, the user no longer needs to carry a demineralized water tank on his car, nor to find a service station selling demineralized water, he only needs to find a tap and fill the tank with such water, for example with a water pipe or a kettle.

In various embodiments, which will be described later, the water poured by the user into the tank is introduced into the recirculation circuit of the spraying system, which is a circuit in which the water will pass through the filter as many times as necessary to demineralize. We refer to the water passing through the recirculation loop as "recirculated water".

In a particular embodiment of the invention, the filter is placed in both the supply circuit of the tank and the recirculation circuit of the tank. In this embodiment, the water poured into the water supply circuit is filtered for the first time before filling the tank. This configuration of the filter is particularly advantageous when the tank is full of rainwater. In fact, rain water generally contains more minerals and impurities than tap water.

In a preferred embodiment of the invention, the filter is placed in the only recirculation circuit of the tank. In the preferred embodiment, the tank can be filled more quickly thanks to the absence of a filter in the supply circuit, and therefore to the absence of pressure losses in the supply circuit.

According to an additional feature of the invention:

the system also comprises an injection conduit intended to be connected to the intake circuit of the jet engine, the system being configured so that the aqueous solution from the filter passes through the tank before entering the injection conduit.

The supply circuit comprises a supply pipe connected to the tank and a filling tank of the tank connected to the supply pipe. The filling point of the tank is therefore not connected to where the tank is located in the vehicle.

The recirculation circuit comprises an inlet conduit into the tank and an outlet conduit out of the tank. In this way, the water is recirculated outside the tank, which has the advantage of making the filter easier to access when it is placed in the recirculation circuit.

The aqueous solution is water, in particular tap water or rain water, and the filter is a filter for removing minerals and/or impurities. In this way, mineral substances and/or impurities possibly present in the water of the tank are prevented from entering the injection circuit of the engine.

The demineralizing filter is a demineralizing filter comprising a filter medium composed of an ion exchange resin. Thus, even very hard water can be demineralized.

The filter for removing impurities is a fine filter. This is particularly advantageous when the water of the tank has suspended particles in addition to minerals, since these particles may block the spray circuit.

The filter is a removable interchangeable filter. In this way, maintenance of the filter is facilitated.

The filter comprises a washable, reloadable or disposable filter cartridge. Thus, the filter can be cleaned, reinstalled, or replaced as desired.

The filter comprises heating means adapted to heat the aqueous solution. This is particularly advantageous when the water present in the filter is frozen and has to be thawed.

The spraying system according to the invention also comprises a quality sensor of said aqueous solution. Thus, by minimizing the recirculation time of the water, i.e. the minimum time required for the recirculated water to have the desired physicochemical properties, the service life of the filter is extended. In doing so, the life of the pump is extended, noise is reduced and power consumption is reduced.

According to the present invention, there is also provided a purification method of an aqueous solution for an injection system that injects the aqueous solution into an injection engine, the purification method comprising the steps of:

-filling the tank with an aqueous solution through the supply circuit,

-pumping the aqueous solution contained in the tank,

-conveying the pumped aqueous solution into a recirculation loop of the aqueous solution,

-filtering the aqueous solution in the supply circuit and/or in the recirculation circuit.

Preferably, the purification method further comprises, after the filtering step, the steps of:

-transferring said aqueous solution into a tank,

-conveying the aqueous solution into an injection duct intended to be connected to the intake circuit of an injection engine.

According to the present invention, there is also provided an evaluation method of an aqueous solution for an injection system that injects the aqueous solution into an injection engine, the evaluation method including the steps of:

-measuring the physicochemical property σ of the aqueous solution contained in the tank,

-measuring the physicochemical property σ_mWith reference value range [ sigma ]_ref.min，σ_ref.max]Making a comparison, in which reference value range σ_ref.minIs the minimum reference value, σ_ref.maxIs the maximum reference value for the value of the reference,

if the physicochemical property σ is measured_mIn the reference value range [ sigma ]_ref.min，σ_ref.max]And, in addition, the aqueous solution is conveyed to a demineralization filter,

as long as the physicochemical property σ is measured_mIn the reference value range [ sigma ]_ref.min，σ_ref.max]In addition, the previous steps are repeated,

if the physicochemical property σ measured after the predetermined time T_mStill within the reference value range [ sigma ]_ref.min，σ_ref.max]Otherwise, a problem is indicated by the signal S. The signal S is typically an indicator light that lights up on the dashboard of the vehicle. Advantageously, T is between 3 and 30 minutes.

Finally, according to the invention, there is provided an injection method of injecting an aqueous solution into an injection engine, the injection method comprising the steps of:

-measuring the physicochemical property σ of the aqueous solution contained in the tank,

-measuring the physicochemical property σ_mWith reference value range [ sigma ]_ref.min，σ_ref.max]Making a comparison, in which reference value range σ_ref.minIs the minimum reference value, σ_ref.maxIs the maximum reference value for the value of the reference,

if the physicochemical property σ is measured_mIn the reference value range [ sigma ]_ref.min，σ_ref.max]And delivering the aqueous solution to the injection engine.

Drawings

We will now describe, by way of non-limiting example, different embodiments of the invention with the aid of the following drawings:

figure 1 is a schematic cross-sectional view of an injection system for injecting an aqueous solution into an injection engine according to an embodiment not belonging to the invention,

figure 2 is a schematic cross-sectional view of an injection system for injecting an aqueous solution into a jet engine according to a first embodiment of the invention,

figure 3 is a schematic cross-sectional view of an injection system for injecting an aqueous solution into a jet engine according to a second embodiment of the invention,

figure 4 is a schematic view of a filter cartridge according to the invention,

fig. 5 is a schematic view of another cartridge according to the invention.

Detailed Description

The injection system for injecting an aqueous solution into the intake circuit of an injection engine, as shown in fig. 1, comprises a tank 10 intended to receive the aqueous solution, preferably water. In the embodiment shown, the tank is made of two half-shells obtained by moulding a plastic material. The two half-shells are heat-welded to each other along the junction plane P to form a closed tank. The components are introduced and fixed in the tank before the tank is closed by heat welding. In operation, water (not shown) in the tank is pumped by the feed pump 20. The feed pump 20 is an electric pump arranged inside the tank 10, at the bottom of the tank 10, and is part of the water supply module 30 of the jet engine. The water supply module, also called wdm (water Delivery module) in english, is a set of components arranged to supply pressurized water to the jet engine M. Among the components of the WDM module are a water pump like the feed pump 20 and an injection conduit 40 for injecting pressurized water into the engine M. There is also a temperature sensor 50 for measuring the water temperature and a quality sensor 60 for measuring one or more physicochemical properties of the water. In addition, the WDM module can house a stabilization tank 70, also known in english as "swirl pot" (swirl tank), which stabilization tank 70 is intended to permanently store a certain quantity of water, which is useful for the good functioning of the feed pump 20. There is also a water level sensor (not shown) inside or outside the stabilization tank 70.

In operation, pumped water is delivered under pressure through injection conduit 40 into the intake circuit (not shown) of the injection engine M. In one particular embodiment of the invention, water is injected into the engine at a pressure of 10.5 bars.

Recall that the purpose of the water injection system is to reduce the temperature of the air-fuel mixture at the inlet of the combustion chamber of an injection engine. Thanks to this system, better compression resistance of gasoline engines and better combustion in diesel engines are obtained. The water also has a cooling effect on the internal parts of the engine (piston and cylinder). This can reduce pollution (under-combusted particulates, CO, NOx) and save fuel, which can be as much as 25% when used intensively.

In the water injection system of the engine, the supply pump 20 is controlled by an Electronic Control Unit ECU (english "Electronic Control Unit") of the injection engine. The ECU unit acts on the action devices such as the injector, the intake throttle, the pump, etc., according to information it receives from sensors such as a position sensor of an accelerator pedal, an engine temperature sensor, an air temperature sensor, an oxygen ratio sensor, etc. When the ECU unit deems that all the conditions required to be able to inject water into the engine M are satisfied, it controls the feed pump 20 to be activated. However, in order not to cause scale in the injection circuit comprising, inter alia, the injection conduit 40 and the water injector (not shown), the water injected into the engine M is demineralized, i.e. in principle free of, for example, Ca²⁺And HCO₃ ^-And any ionized water. In the automotive industry, water is considered demineralized when its conductivity is less than 100. mu.S/cm at 25 ℃. Sometimes, the requirements are more stringent and water is considered demineralized if its conductivity is less than 50. mu.S/cm at 25 ℃.

There is a limitation in filling the tank with demineralized water. In fact, demineralized water is not naturally available, and the driver of a vehicle equipped with such a spraying system must carry the demineralized water tank with him on the trip, since about 3 liters of demineralized water must be prepared per 1000 kilometers of travel. Of course, demineralized water can be purchased at a fueling station, but the driver is not available at all fueling stations.

A first object of the present invention is to eliminate the limitation of having to use demineralized water in the water injection system of an internal combustion engine. To this end, the invention proposes that the water be filtered in a demineralization filter before it is injected into the internal combustion engine. Thereby, and thanks to the invention, the tank can be filled with tap water or rain water without the risk of scale being generated by the water injection circuit. Thus, the driver no longer needs to be burdened with preparing the demineralized water tank prior to travel or to find and purchase the demineralized water at a refueling station.

In a preferred embodiment of the invention, the water injection system comprises a tank 10 of water, a supply circuit 80 of the tank 10, a recirculation circuit 90 of the water of the tank 10 and a filter 100 filtering the water of the tank 10. The supply circuit 80 consists of a supply pipe 81 and a filling tank 82, through which tank 82 water is introduced into the water injection system. The supply pipe 81 has two ends, a first end 81a connected to the filling tank and a second end 81b connected to the tank 10 from the outside and opening into the upper part of the tank 10. Means (not shown) are provided for ensuring the tightness of these connections. As with the supply circuit 80, the recirculation circuit 90 is connected externally to the tank 10.

According to the embodiment shown in fig. 1, which is not part of the invention, the recirculation circuit 90 consists of an inlet pipe 91 entering the tank 10 and an outlet pipe 92 leaving the tank, and the inlet pipe 91 in the tank opens into the upper part of the tank 10 and the outlet pipe 92 of the tank opens into the lower part of the tank 10.

In the context of this specification we refer to the first filled part of the tank as the lower or bottom part of the tank and the last filled part of the tank as the upper part of the tank. Similarly, the volume bounded by the tank wall in which water is stored is referred to as the interior of the tank, and the open volume around the tank is referred to as the exterior of the tank.

A filter 100 for filtering the water of the tank 10 is placed in the recirculation circuit 90. In the embodiment shown in fig. 1, which is not part of the invention, the filter 100 is placed between the outlet conduit 92 of the tank and the inlet conduit 91 of the tank.

According to the present invention, the filter 100 is a demineralization filter, such as a filter comprising a filter medium composed of an ion exchange resin. A recirculation pump 20' controlled by the ECU unit pumps the water contained in the tank 10 to pressurize it for feeding into the recirculation circuit 90 when the water is not demineralized or into the intake circuit of the engine through the injection duct 40 when the water is demineralized. The water exiting the tank 10 is demineralized water which no longer needs to pass through a demineralized filter before being delivered into the intake circuit of the engine. In this advantageous embodiment, the recirculation pump 20' and the supply pump 20 form only one pump. To determine which circuit to deliver water, the ECU unit relies on the information provided by the quality sensor 60 to learn the ion concentration of the water. The quality sensor is for example a sensor of the electrical conductivity of water. The quality sensor is placed inside the tank 10, at the bottom of the tank 10, preferably inside the stabilization tank 70, so that the quality sensor remains immersed in the water even in the case where the tank 10 is almost empty. In case the quality sensor 60 is a sensor continuously measuring the electrical conductivity of the water contained in the tank 10, the obtained measured value is compared with a reference value range of the electrical conductivity, such as [0, 100] mus/cm, preferably [2, 50] mus/cm, where 0 mus/cm, 2 mus/cm are minimum reference values, respectively, and 100 mus/cm, 50 mus/cm are maximum reference values, respectively. If the measured value is outside the reference value range, the ECU unit commands the pump 20 to deliver water into the recirculation loop 90 to demineralize the water. On the contrary, if the measured value is within the reference value range, the ECU unit commands the pump 20 to deliver the water of the tank 10 through the injection duct 40 into the intake circuit of the engine without passing through the other demineralization filter. It may happen that the measured value is still outside the reference value range and water is no longer injected into the engine. This may occur, for example, when filter 100 is clogged, damaged, or missing. In this case, the ECU unit indicates that the filter is in problem by illuminating a signal lamp on the dashboard of the vehicle. In response to the signal, the driver or technician responsible for servicing the vehicle equipped with the spray system will clean, reinstall or replace the filter.

Advantageously, the demineralized filter 100 is a removable interchangeable filter for easy removal and replacement by the driver or technician responsible for vehicle maintenance. In a preferred embodiment of the present invention, the removable interchangeable demineralized filter is a cartridge 110 (see FIG. 4) including a filter media comprised of ion exchange resin. The filter cartridge is housed in such a filter housing 101 comprising an inlet hole 101a and an outlet hole 101b for water. The filter housing 101 is mounted in the recirculation circuit 90 between the outlet conduit 92 exiting the tank and the inlet conduit 91 entering the tank, so that the water exiting the tank 10 from the outlet conduit 92 enters the filter housing 101 through the inlet hole 101a of the filter housing 101, then passes through the filter cartridge 110, and then re-exits the filter housing 101 through the outlet hole 101b of the filter housing 101 to return to the tank 10 through the inlet conduit 91. To facilitate servicing of the filter cartridge 110, the filter housing 101 is positioned in an easily accessible area of the vehicle, such as under the hood.

In addition to the above elements and components, a ventilation device 11 is provided at the upper part of the tank 10 to equalize the pressure between the inside and the outside of the tank 10. The ejector pump 12, connected to the check valve 13 and the suction tube 14, is used to fill the stabilization tank 70 to ensure good operation of the WDM module. Heating means 15 are also provided inside the tank 10 to thaw the water when the water in the tank freezes. The heating means 15 is typically a heating resistor fixed to the bottom of the tank 10. When filling the tank 10 through the filling tank 82, it is advantageous to fill the stabilization tank 70 first, for which purpose the inner tube 16 is added during the manufacture of the tank 10. The tube 16 is located inside the tank and extends between two ends: one end is connected in a sealed manner to the supply pipe 81 through the inside of the tank 10, and one free end opens above the stabilization tank 70 and is turned towards the stabilization tank 70. Thus, when water is poured into the tank filling tank 82, it flows into the supply pipe 81 and then into the pipe 16 before passing into the stabilization tank 70.

In the embodiment shown in fig. 1, which is not part of the invention, the second inner tube 17 is placed in the tank during the manufacture of the tank 10. The pipe 17 is a pipe extending between the feed pump 20 and the outlet conduit 92 of the tank 10 to connect said pump to the recirculation circuit 90. Thus, when the ECU unit controls the feed pump 20 to deliver the water of the tank 10 into the recirculation circuit 90, this water is delivered under pressure into the recirculation circuit 90 through the pipe 17. Delivering water under pressure into the recirculation loop 90 (i.e., into the filter 100) is particularly advantageous because it avoids pressure losses in the recirculation loop 90 due to water flowing into the filter 100.

During the manufacture of the tank 10, the third inner tube 18 is placed in the tank. Like tube 16, tube 18 is used to fill the stabilization tank 70. The tube 18 extends between two ends: one end is connected in a sealed manner to an inlet pipe 91 in the tank, and a free end opens above the stabilization tank 70 and in the opposite direction to the stabilization tank 70.

According to a first embodiment of the invention, shown in fig. 2, the injection system comprises an electric valve 130 controlled by the ECU unit. The electric valve 130 is a three-way electric valve comprising a first inlet 130a connected to the filling tank 82, a second inlet 130b connected to the inlet duct 91 of the recirculation circuit 90 and an outlet 130c connected to the feed duct 81 of the supply circuit 80. Thus, during filling of tank 10 through filling slot 82, ECU unit control electro valve 130 opens filling circuit 83 and supply circuit 80, and closes recirculation circuit 90. The priming circuit 83 is the portion of the supply circuit 80 that is upstream of the electric valve 130. After the tank 10 is full, the ECU unit commands the electro valve 130 to close the filling circuit 83 and open the recirculation circuit 90. Thus, the water of the tank is recirculated in the recirculation circuit 90, so that the water is filtered by a filter 100 placed in the recirculation circuit 90.

Thanks to this particular configuration of the spraying system according to the invention, the water recirculated in the recirculation circuit 90 returns to the tank 10 through the internal pipe 16, thus limiting the number of pipes in the tank 10 by eliminating the internal pipe 18.

Fig. 3 shows an embodiment variant of the first exemplary embodiment of the invention. In this second embodiment, a filter 100 is placed in the supply circuit 80. Thanks to this particular configuration of the spraying system, the water poured into the filling tank 82 is filtered for the first time before filling the tank 10.

Fig. 4 is a schematic view of a demineralized filter element 110. The filter element 110 is generally composed of a hollow body 111 filled with a filter medium, such as an ion exchange resin. The filter element has an inlet 111a for water to be filtered and an outlet 111b for filtered water. The inlet 111a of the filter element communicates with the inlet hole 101a of the filter housing 101, and the outlet 111b of the filter element communicates with the outlet hole 101b of the filter housing 101. Seals 110a and 110b are coupled to the filter cartridge to ensure that all water exiting the filter housing 101 passes through the filter cartridge 110. Furthermore, the heating means 102 of the filter 100 are arranged to thaw water that may freeze in the filter, e.g. due to weather conditions. These heating means 102 are typically heating resistors housed inside the filter housing 101 or alternatively outside the filter housing 101.

In fig. 5, an embodiment variant of the filter insert is shown, in which a fine filter 120 is connected to the demineralization filter 110. A fine filter is a porous body (felt, paper, membrane, mesh, etc.) through which a liquid is passed to clarify or purify it. In the present invention, a fine filter is used to filter impurities present in the water, such as suspended particles, organic debris. In a preferred embodiment, the mesh width of the fine filter is between 30 μm and 60 μm.

Of course, many modifications may be made to the present invention without departing from its scope.

For example, the recirculation loop 90 may be connected by an inlet conduit and an outlet conduit inside the tank 10, rather than by an inlet conduit and an outlet conduit outside the tank 10. Thanks to this configuration, it is possible to envisage placing the filter 100 in a housing arranged in the wall (not shown) of the tank 10. Such a receptacle would be hermetically closed by a screw-off lid so that the lid could be unscrewed to render the filter removable and interchangeable. In this configuration, the number of pipes and tubes outside the tank is reduced, and heating of the filter is additionally facilitated.

In addition, in order to have a water jet system according to the invention with reduced weight and impact resistance, the tank may be made of plastic, for example High Density Polyethylene (HDPE). Advantageously, the pipes and tubes can also be made of plastic, as can the filter housing.

In addition, the ion concentration of the water contained in the tank, and thus whether it is demineralized, can be determined by measuring properties other than the conductivity of the water. For example, measurements of the resistivity, hardness, density, turbidity or pH of water may also give good information as to whether the water is demineralized or not. Thus, the quality sensor described above may alternatively be a resistivity sensor, a hardness sensor, a density sensor, a water turbidity sensor or a pH probe. Thus, any type of sensor capable of measuring such physicochemical properties of water that provide information indicative of the ion concentration of the water is referred to as a quality sensor. Thus, in case the quality sensor 60 is a sensor continuously measuring the resistivity of the water of the tank 10, the reference value range will extend from 20k Ω -cm to infinity, and preferably between 40k Ω -cm to 500k Ω -cm.