WO2011048292A2

WO2011048292A2 - Device for injecting a liquid additive material into a treatment line

Info

Publication number: WO2011048292A2
Application number: PCT/FR2010/051846
Authority: WO
Inventors: Rodolphe Emaille
Original assignee: Mgi Coutier
Priority date: 2009-10-23
Filing date: 2010-09-06
Publication date: 2011-04-28
Also published as: FR2951775B1; FR2951775A1; WO2011048292A3

Abstract

The invention relates to a device for injecting a liquid additive, including an additive tank (3) connected by means of an additive pipe (4) to an injector (5) that is placed on a treatment line (3) of a member for removing pollution from a motor vehicle provided with a heat engine. An intake and exhaust pump (6) is placed on the additive pipe (4). An accumulator (7) is connected to the additive pipe (4) between the pump (6) and the injector (5). The pump (6) is cylindrically actuated so as to fill the accumulator (7) with an amount of pressurized additive material that said accumulator then directs to the injector (5). The invention is of use for injecting a reducing additive, made up of a mixture of water and urea, so as to remove pollution from a diesel engine.

Description

Device for injecting a liquid additive product into a treatment line

The present invention relates, in a general manner, to the field of depollution in relation to motor vehicles with a heat engine, in particular with a diesel engine. More particularly, this invention relates to a device for injecting a liquid additive product, in particular a product with a reducing function, into a treatment line of a pollution control member of a motor vehicle equipped with a heat engine. .

The technology used for the depollution of nitrogen oxides NOx, on vehicles with a heat engine such as a diesel engine, requires a device for pressurizing a liquid additive product, in particular at a pressure of between 5 and 20 bars, in order to to allow injection in the form of fog in a treatment line, more particularly in the exhaust line of the vehicle concerned. The additive used is in particular a product based on urea, mixed with water.

In a generally known manner, to perform the injection function of such an additive product in a treatment line, there is provided a device which comprises an additive reservoir connected by an additive conduit to at least one injector. additive placed on the treatment line, means for pumping and pressurizing the additive being placed on the additive duct between the additive reservoir and the additive injector.

Thus, the patent document FR 2 879 239 describes a device in which the pressurization of the additive, consisting of an aqueous solution of urea, is carried out by a pump which takes the additive from a storage tank of this additive. itif, and that directly sends the additive in an injection line leading to the injector, a return line bringing back to the reservoir the surplus of additive, not consumed by the injector. In such an embodiment, the pump operates as soon as the engine is started and permanently. This pump must therefore be designed to operate throughout the life of the vehicle, typically operating for 8000 hours over 1 5 years for a total distance of 240000 kilometers. Thus the pump must be made with particularly robust and expensive components to withstand the thermal and mechanical stresses of permanent operation, and also corrosion by the additive product used. According to another known solution, described in patent document FR 2 870 172 or its equivalent, patent document WO2005 / 1 13279, the additive is stored in a reservoir in the form of a flexible bag contained in a rigid cartridge and capable of be pressurized by a compression spring. In this case the pump can be omitted, but the pressure of the additive upstream of the injector is proportional to the spring force and inversely proportional to the surface of the pocket in contact with a plate on which the spring. In practice, the volume of additive to be stored in the bag being relatively large, typically between 15 and 20 liters, this solution requires a relatively large pocket area, of the order of several tens of cm 2, and spring forces very important, up to several hundred daN if it is desired to obtain a high injection pressure, typically between 5 and 10 bar. Given the constraints of space available on vehicles, a spring that can meet all these requirements certainly does not exist, and such a solution "without pump" is not realistic.

In a variant provided by the aforementioned patent document FR 2 870 172, the flexible pouch is pressurized by a pump integrated in the vehicle and having another main function, such as the function of supplying the engine with fuel. In this case, the bag must already be compatible vis-à-vis the two fluids with which it is in contact respectively by its inner and outer faces, and the respective temperatures of these fluids. In addition, this solution has an impact on the pump, whose operating point is changed due to the increase in the volume of fluid between the bag containing the additive and the rigid cartridge. Thus, a pressure regulator must be added to the pump for proper operation.

The present invention aims to avoid the aforementioned disadvantages, and it therefore aims to provide a device for injecting a liquid additive product, capable of putting the additive product under a suitable pressure for injection into a line of treatment, by pumping the additive but with simplification and lightening of the construction and operation of pressurizing means of this additive, to size the components to what is just necessary while ensuring their operation on any the life of the vehicle. For this purpose, the subject of the invention is a device for injecting a liquid additive product, in particular a product with a reducing function into a treatment line of a pollution control device of a motor vehicle equipped with an engine. thermal device comprising an additive tank connected by an additive duct to at least one additive injector placed on the treatment line, and means for pumping and pressurizing the additive placed on the duct additive between the additive reservoir and the additive injector, this device being characterized in that the said means for pumping and pressurizing the additive comprise, on the one hand, a suction pump and a pressure pump placed on the additive duct and, on the other hand, an accumulator connected to the additive duct between the pump and the additive injector, so that the pump can be actuated cyclically to fill the accumulator with a quantity of product addit if this accumulator then directs to the additive injector.

Thus, the additive is temporarily stored under pressure in an accumulator, which makes it possible to supply the injector without a source of energy for a time which is a function of the volume of the accumulator and the injection rate of the additive in the treatment line. The additive filling of the accumulator is performed only cyclically, when the accumulator is empty at the end of the aforementioned time, with the aid of a pump carrying out the pressurization of the additive. The operating time of the pressurizing pump of the additive, carrying out the pressurization of an elementary quantity of additive in an accumulator, is greatly reduced in comparison with the previous embodiments, which makes it possible to envisage a a simpler and more economical pump, based on injected plastic components and a current-type electric motor for driving the rotary members of the pump.

Advantageously, this pump is a rotary pump, such as a gear pump, with two directions of rotation.

By also providing a solenoid valve interposed on the additive duct, between the pump and the accumulator, it becomes easy to achieve with this pump, driven in the opposite direction to that of the filling, a purge of the accumulator and more generally hydraulic circuits containing additive, for draining these hydraulic circuits, in particular for frost protection, or to put them at atmospheric pressure when the vehicle is stopped to avoid unnecessary operation of the device. If he is renounced these advantages, the solenoid valve can be replaced by a simple non-return valve.

In one embodiment of the injection device of the invention, the accumulator comprises a cylindrical body and a piston, associated with a sealed membrane, which is slidably mounted in the cylindrical body and subjected to the effect of a spring , the piston with its diaphragm delimiting in the cylindrical body a variable volume chamber, in communication with the additive conduit and receiving said amount of additive product.

Advantageously, two sensors are arranged against the wall of the cylindrical body of the accumulator to detect the end positions of the piston and control the start and stop of the pump, each battery filling cycle. Alternatively, these two position sensors are replaceable by a single sensor detecting the instantaneous position and movement of the piston, this alternative solution providing the following advantages:

- By a correlation law between the instantaneous position of the piston and the force produced by the spring of the accumulator, it is possible to determine at any time the actual value of the pressure of the additive in the accumulator, so in upstream of the injector.

- By measuring the sensor displacement between two (or more) consecutive additive injections, it is also possible to determine the volume of additive actually injected, and this regardless of the value of the counter-pressure ion in lal ig no treatment, especially the vehicle exhaust line.

Thus, the filling of the accumulator by means of the pump is realized only when this accumulator is empty or almost empty, the information on the "empty" state of the accumulator being delivered by a sensor. As soon as the piston reaches its other limit position, the second sensor or the same sensor (as the case may be) causes the pump to come back to a standstill.

Such a device therefore makes it possible to turn the pump only when there is a need to fill the chamber of the accumulator with additive, for example every twenty to thirty kilometers traveled by the vehicle, for example by bringing a volume of 20 cm 3 additive at each filling cycle. The total number of operating cycles of the device is thus relatively low during the life of the vehicle, for example 12000 cycles for a total distance of 240000 kilometers. Moreover, since the filling time of the accumulator is only a few seconds, for example 5 seconds at each cycle, the total running time of the pump is accordingly also reduced and limited to a few hours or tens of seconds. hours, for example the pump and its motor will only work about 20 hours in total, instead of 8000 hours in a traditional device. This aspect is decisive for the choice of a pump with simple and economical components.

According to another advantageous aspect of the device of the invention, the pump is designed to be driven in the opposite direction to that of the filling of the accumulator, for filling the additive reservoir from an additive container. constituting a refill, this additive container being connected to the additive duct by a hydraulic connection with non-return valve. Thus, by a specific control sequence of the pump, and simply providing a hydraulic connector equipped with a non-return valve, it is possible to refill the additive reservoir when it is empty, s' franking a set with chute and plug and a specific filling system.

The invention will be better understood, and other advantages will be highlighted, with the aid of the description which follows with reference to the appended schematic drawing representing, by way of examples, some embodiments of this device. injecting an additive product into a treatment line.

FIG. 1 is a block diagram of an additive injection device, according to the present invention, in a first embodiment with solenoid valve,

FIG. 2 is a block diagram of an additive injection device according to the present invention, in a second embodiment with non-return valve,

Figure 3 is a diagram similar to that of Figure 1, illustrating the possibility of filling the additive tank with the device of the invention;

Figure 4 is a partial view illustrating a variant.

In FIGS. 1 to 3, a treatment line is very schematically shown, and more particularly the exhaust line 2 of a motor vehicle with a combustion engine, in particular a motor of the type a liquid additive with a depolluting function, which is in particular a mixture of water and urea in predefined proportions (typically: urea dissolved in water at a rate of 33%), or any another mixture of water and urea to which chemical or organic compounds can be added improving the efficiency and / or the behavior of the additive as a function of thermal and climatic stresses, for example improving the behavior at low temperatures by lowering the gel temperature of the additive.

The liquid additive is stored in an additive reservoir 3 which is connected by an additive conduit 4 to an electromagnetic additive injector 5 placed on the exhaust line 2.

At the start of the additive duct 4 is placed a suction and discharge pump 6, which is in particular a rotary pump with two directions of rotation, driven in one direction or the other by an electric motor which is itself two-way rotation (not shown). The pump 6 is for example a gear pump.

On the additive duct 4, downstream of the pump 6, is connected an accumulator 7. The accumulator 7 comprises a cylindrical body 8, a piston 9 associated with a sealed membrane and slidably mounted in the cylindrical body 8 and a spring 10 compressed between the bottom of the cylindrical body 8 and the piston 9.

The piston 9 with its membrane delimits, in the cylindrical body 8, a chamber 1 1 of variable volume which is in free communication with the additive duct 4.

Two end-of-travel sensors 12 and 13, implanted on the same electronic card 14, are arranged against the wall of the cylindrical body 8 of the accumulator 7, so as to be able to detect two extreme positions of the piston 9 in said cylindrical body 8.

In the embodiment of FIG. 1, a solenoid valve 15 is interposed on the additive pipe 4 between the pump 6 and the accumulator 7. The solenoid valve 15 makes it possible to hydraulically connect the pump 6 to the accumulator 7 to purge the accumulator 7 and the additive duct 4, which is advantageous for avoiding problems related to the freezing of the additive, or if it is not desired to maintain the additive duct 4 and the injector 5 under pressure when the vehicle is stopped. In the embodiment of Figure 2, the solenoid valve previously considered is replaced by a non-return valve 1 6, also inserted on the additive conduit 4 between the pump 6 and the accumulator 7. This second form execution is simpler and more economical than the previous one, but it does not allow to purge the hydraulic circuits or put them at atmospheric pressure.

The basic operation of the device, in one or other of the two embodiments described above (FIGS. 1 and 2), is as follows:

Initially, it is assumed that the accumulator 7 is empty, that is to say that it contains a minimum or no amount of additive, the piston 9 occupying its low end position, determined by the sensor 12, and the chamber 1 1 thus having its minimum volume.

By starting the pump 6, and opening the solenoid valve 15 (the case of Figure 1), the additive is sucked from the additive tank 3, and discharged into the additive line 4. The accumulator 7 is thus filled with additive, admitted into the chamber 1 1 by pushing the piston 9, which compresses the spring 10. The filling of the accumulator 7 continues thus until detection of the upper end position of the piston stroke 9 by the sensor 13. Taking into account the design of the accumulator 7 and the presence of the spring 10, the additive pressure variation in this accumulator 7, and also in the additive line 4 upstream of the injector 5, is linear over the entire stroke of the piston 9.

The arrival of the piston 9 in the upper end position, detected by the sensor 1 3, causes the pump 6 to be stopped. The additive is then injected into the treatment line 2, with a defined flow rate. by the characteristics of the accumulator 7, the additive duct 4 and the injector 5.

This process continues until detection by the sensor 12 of the low end position of the piston 9, meaning that the accumulator 7 is empty or almost empty. The pump 6 can then be automatically restarted, for a new cycle of filling / emptying the accumulator 7, and so on ...

It is possible to integrate in the electronic card 14 the law of variation of the pressure of the additive as a function of the volume taken by the injector 5, in order to have a better precision on the flow rate of the injector.

In addition, the accumulator 7 having a capacity defined by construction, it is possible, by a simple counting of the number of cycles of filling of this accumulator 7, automatically calculate at any time the volume of additive remaining available in the additive tank 3, ititially full. Thus, it is feasible gauging that can be very accurate (accuracy less than ± 1%) and that gives the driver of the vehicle warning information if the amount of additive remaining in the additive tank 3 becomes low and requires a new filling of this tank. Such precision is to be compared with the low accuracy, of the order of ± 15% of conventional gauge systems using a float.

FIG. 3 illustrates an advantageous mode of filling of the additive tank 3, with use of the device of the invention and in particular of its pump 6 with two directions of rotation. An additive can 17, used as a refill, is connected to the additive duct 4 by a hydraulic connection 18 equipped with a nonreturn valve 19, the connection 18 being situated between the pump 6 and the solenoid valve 15. The pump 6 is then driven in the opposite direction from its normal use, so as to suck the additive contained in the additive can 17 and to send this additive into the additive tank 3.

In the configuration of Figure 3, it is also possible to drain the additive tank 3, prior to filling, to extract a remaining additive that can be degraded by a long storage period, this by a command of the pump 6 in the direction of the direct bleed of the additive, and keeping the solenoid valve 15 closed.

To make possible the two modes of operation illustrated in Figure 3, the connection 1 8 and the check valve 19 are advantageously part of the same room and constitute a self-closing valve; when the can 1 7 is connected to the connection 1 8, the non-return function of the valve 19 is neutralized, allowing the flow of the additive in one direction or the other.

Finally, FIG. 4 illustrates a variant relating to the accumulator 7, this variant being compatible with the various embodiments described above. A single sensor 20, in particular of linear type, is here associated with the accumulator 7, and replaces the two end-of-travel sensors while providing additional information, since it continuously measures the position and displacement of the piston 9. Thus, the sensor 20 not only detects the arrival of the piston 9 in its two end positions, to control the start and stop of the pump, but it also allows, by measuring the displacement of the piston 9 between two (or several) consecutive injections, to determine the amount of additive actually injected. In addition, this sensor 20 makes it possible to determine at all times the real value of the pressure in the accumulator 7, thus also in the additive line 4 upstream of the injector 5.

It is not departing from the scope of the invention, as defined in the appended claims:

- Realizing the device with an additive tank which can be of any type, in particular a rigid tank or on the contrary a tank consisting of a flexible bag,

by producing the accumulator in any suitable form, the piston and diaphragm accumulator as described being replaceable for example by a bladder-type accumulator inflated with an inert gas such as nitrogen,

using the device for the injection of liquid additives of any kind, which may be urea-based additives for nitrogen oxide treatment applications, or ceria-based additives used in depollution of particles,

by operating this device under all pressure and flow conditions, the additive pressure upstream of the injector being easily adjustable by modifying the stiffness of the accumulator spring and / or by modifying the section of this accumulator.

Claims

1. Device for injecting a liquid additive product, in particular a product with a reducing function, into a treatment line (2) of a pollution control device of a motor vehicle equipped with a heat engine, the device comprising a reservoir additive (3) connected by an additive duct (4) to at least one additive injector (5) placed on the treatment line (2), and means for pumping and pressurizing the additive placed on the additive duct (4) between the additive tank (3) and the additive injector (5), characterized in that said means for pumping and pressurizing the additive comprise, on the one hand, a pump (6) suction and discharge, placed on the additive duct (4) and, on the other hand, an accumulator (7) connected to the additive duct (4) between the pump (6) ) and the additive injector (5), so that the pump (6) can be actuated cyclically to fill the accumulator (7) with a quantity of additive product, this accumulator (7) then directs to the additive injector (5).

2. Device for injecting an additive product according to claim 1, characterized in that the pump (6) is a rotary pump, such as a gear pump, with two directions of rotation.

3. Device for injecting an additive product according to claim 1 or 2, characterized in that a solenoid valve (15) or a non-return valve (16) is interposed on the additive duct (4), between the pump (6) and the accumulator (7).

4. Device for injecting an additive product according to one of claims 1 to 3, characterized in that the accumulator (7) comprises a cylindrical body (8) and a piston (9), associated to a sealed membrane, which is slidably mounted in the cylindrical body (8) and subjected to the effect of a spring (10), the piston (9) with its diaphragm delimiting in the cylindrical body (8) a chamber (1) 1) of variable volume, in communication with the additive duct (4) and receiving said amount of additive product.

5. Device for injecting an additive product according to claim 4, characterized in that two sensors (12, 13) are arranged against the wall of the cylindrical body (8) of the accumulator (7), to detect the positions end of piston stroke (9) and switch on and off the pump (6) each time the accumulator is charged (7).

6. Device for injecting an additive product according to claim 4, characterized in that a single sensor (20), detecting the instantaneous position and the displacement of the piston (9), is associated with the accumulator (7). .

7. Device for injecting an additive product according to Claims 2 and 3, with a solenoid valve (15) interposed on the additive duct (4), characterized in that the pump (6) is provided for be driven in the opposite direction to that of the filling of the accumulator (7), in order to drain the hydraulic circuits containing the additive in particular for an anti-freeze, or to put them at atmospheric pressure when the vehicle is at shutdown.

8. Device for injecting an additive product according to claim 2 or 7, characterized in that the pump (6) is provided to be driven in the opposite direction to that of the filling of the accumulator (7), in order to filling the additive tank (3) from an additive container (17) constituting a refill, said additive container (17) being connected to the additive line (4) via a hydraulic connection ( 18) with non-return valve (19).

9. Device for injecting an additive product according to Claims 3 and 8, characterized in that it is provided for draining the additive reservoir (3) in order to extract a remainder of additive, this by a control of the pump (6) in the direct drawing direction of the additive, and maintaining the solenoid valve (15) closed.