Device for providing a liquid additive

Abstract

A device for providing a liquid additive includes at least one first pump chamber (3) for conveying the liquid additive, and a rotary drive. The first pump chamber is arranged around a drive axis of the rotary drive. Inside the first pump chamber, at least one seal is formed, which can be displaced from the rotary drive around the drive axis. The device has at least one second pump chamber, which is arranged along the drive axis adjacent to the first pump chamber.

Claims

1. A device (1) for supplying a liquid additive, comprising: a rotary drive (4) having a drive shaft (5); at least one first pump chamber (3) configured to deliver the liquid additive, the first pump chamber (3) being arranged around the drive shaft (5) of the rotary drive (4); at least one seal (6) arranged within the first pump chamber (3), the at least one seal being displaceable around the drive shaft (5) by the rotary drive (4); at least one second pump chamber (7) arranged adjacent to the first pump chamber (3) along the drive shaft (5); and a deformable diaphragm (28) at least partially delimiting at least the at least one first pump chamber (3), the deformable diaphragm (28) forming the at least one seal (6), wherein the deformable diaphragm (28) is configured to be deformable by an eccentric drive (30) connected to the rotary drive (4) to effect displacement of the at least one seal (6), wherein the at least one first pump chamber (3) and the at least one second pump chamber (7) surround the drive shaft (5) in a circular arc segment (9) over at least 250 angular degrees.

2. The device (1) as claimed in claim 1, wherein the at least one second pump chamber (7) is structurally identical to the at least one first pump chamber (3).

3. The device (1) as claimed in claim 1, wherein the at least one second pump chamber (7) is connectable in parallel with the at least one first pump chamber (3) so as to increase the delivery rate of the device (1).

4. The device (1) as claimed in claim 1, further comprising a separable coupling (8) arranged between the at least one first pump chamber (3) and the at least one second pump chamber (7), said separable coupling (8) being configured so as to make the at least one second pump chamber (7) decoupleable from the drive shaft (5).

5. The device (1) as claimed in claim 1, wherein the at least one second pump chamber (7) is connectable in series with the at least one first pump chamber (3) so as to increase the delivery pressure of the device (1).

6. The device (1) as claimed in claim 1, further comprising at least one valve (10) by which at least one connecting line (33) between the at least one first pump chamber (3) and the at least one second pump chamber (7) is switchable.

7. A motor vehicle (11) comprising: an internal combustion engine (22); an exhaust-gas treatment device (12) for purification of exhaust gases of the internal combustion engine (22); and the device (1) as claimed in claim 1 for feeding a liquid additive to the exhaust-gas treatment device (12).

8. A device (1) for supplying a liquid additive, comprising: a rotary drive (4) having a drive shaft (5); at least one first pump chamber (3) configured to deliver the liquid additive, the first pump chamber (3) being arranged around the drive shaft (5) of the rotary drive (4); at least one seal (6) arranged within the first pump chamber (3), the at least one seal being displaceable around the drive shaft (5) by the rotary drive (4); at least one second pump chamber (7) arranged adjacent to the first pump chamber (3) along the drive shaft (5); and a pinch disk (31) connected to the rotary drive (4), and a hose (29) at least partially forming at least the at least one first pump chamber (3), wherein the at least one seal (6) is formed by the hose (29) being compressed in sections by the pinch disk (31), the hose (29) being configured to be deformable by the pinch disk (31) to effect displacement of the seal (6), wherein the at least one first pump chamber (3) and the at least one second pump chamber (7) surround the drive shaft (5) in a circular arc segment (9) over at least 250 angular degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and the technical field will be explained in more detail below on the basis of the figures. The figures show particularly preferred exemplary embodiments, to which the invention is however not restricted. In particular, it should be noted that the figures and in particular the illustrated proportions are merely schematic. In the figures:

(2) FIG. 1: shows a described device for supplying a liquid additive;

(3) FIG. 2: is a sectional illustration, perpendicular to the drive shaft, through a first design variant of a pump for a described device;

(4) FIG. 3: is a sectional illustration, perpendicular to the drive shaft, through a second design variant of a pump for a described device;

(5) FIG. 4: is a schematic illustration of a first design variant of a pump for a described device;

(6) FIG. 5: is a schematic illustration of a second design variant of a pump for a described device;

(7) FIG. 6: is a schematic illustration of a third design variant of a pump for a described device;

(8) FIG. 7: is a schematic illustration of a fourth design variant of a pump for a described device; and

(9) FIG. 8: shows a motor vehicle having a described device.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(10) FIG. 1 shows a device 1 for supplying a liquid additive, which device is inserted into a tank base 16 (only sections of which are illustrated here) of a tank. The device 1 has a housing 15 that seals against the tank base 16. On the device 1 there is provided an intake point 17 at which the device 1 can extract liquid additive from the tank and deliver the liquid additive to a discharge point 18. For this purpose, the device 1 has a pump 2. A delivery duct 13 extends through the device 1 from the intake point 17 to the discharge point 18.

(11) In the sectional illustration of a first design variant of a pump 2 for a described device in FIG. 2, it is possible to see a first pump chamber 3 in the form of a hose 29. The hose 29 forms a delivery duct 13.

(12) The hose 29 is deformed in sections by a pinch disk 31, such that seals 6 are formed within the pump chamber 3. Between the seals 6, the hose forms closed delivery volumes 34 in each case. The pinch disk 31 is aligned correspondingly with the drive shaft 5 of a rotary drive (not illustrated here) of the pump 2. Rotation of the pinch disk 31 about the drive shaft 5 causes a displacement of the (constant) delivery volume 34 and thus a delivery of the liquid additive through the first pump chamber 3 or the hose 29 in the delivery direction 14 from an inlet 26 to an outlet 27.

(13) In the second design variant of a pump 2 for a described device in FIG. 3, the pump chamber 3 or the delivery duct 13 is formed by a pump housing 35 and by a diaphragm 28 arranged within the pump housing 35. The diaphragm 28 is deformed by an eccentric drive 30 such that at least one seal 6 is formed between the pump housing 35 and the diaphragm 28. This seal 6 serves to form closed delivery volumes 34 within the pump chamber 3. The eccentric drive 30 is aligned with a drive shaft 5. Rotation of the eccentric drive 30 about the drive shaft 5 causes the diaphragm 28 to be deformed and the seal 6 to be moved, such that the closed delivery volumes 34 are displaced and liquid additive is delivered through the pump chamber 3 or along the delivery duct 13 in the delivery direction 14 from an inlet 26 to an outlet 27. Between the outlet 27 and the inlet 26 of the pump chamber 3 there is situated a seal in the form of a lug 32 which prevents the possibility of a return flow of liquid additive from the outlet 27 to the inlet 26 counter to the delivery direction 14. For this purpose, the lug 32 is in the form of an element that presses into the diaphragm 28 and produces a fluid-tight connection with the diaphragm 28 regardless of the angle of rotation of the eccentric drive 30.

(14) In the design variant of a pump 2 for a described device as per FIG. 4, the rotary drive 4 is connected via the drive shaft 5 to a first pump chamber 3 and a second pump chamber 7. The second pump chamber 7 can be decoupled from the drive shaft 5 by a coupling 8. The first pump chamber 3 and the second pump chamber 7 are connected to a delivery duct 13 and can be connected in parallel with one another by a connecting line 33.

(15) For this purpose, the connecting line 33 can be opened and closed by a valve 10.

(16) In the design variant of a pump 2 as per FIG. 5, the first pump chamber 3 and the second pump chamber 7 are likewise connected by a drive shaft 5 to a rotary drive 4. In this case, too, the second pump chamber 7 can be decoupled from the drive shaft 5 by way of a coupling 8. The first pump chamber 3 and the second pump chamber 7 are connected to a delivery duct 13. The first pump chamber 3 and the second pump chamber 7 can be connected in series by a connecting line 33. For this purpose, a special valve 10 is provided by which the second pump chamber can be selectively integrated into or removed from the delivery duct 13.

(17) In the design variant of a pump 2 as per FIG. 6, the rotary drive 4 is likewise connected via the drive shaft 5 to a first pump chamber 3 and a second pump chamber 7. In this case, too, the second pump chamber 7 can be decoupled from the drive shaft 5 by the coupling 8. A delivery duct 13 runs through the pump chamber 3. By the two valves 10, connecting lines 33 can be opened up so as to connect the second pump chamber 7 to the delivery duct 13. For this purpose, the valves have different valve positions which make it possible both for the first pump chamber 3 and the second pump chamber 7 to be connected in parallel and for the first pump chamber 3 and the second pump chamber 7 to be connected in series. For this purpose, at the inlet 26 into the first pump chamber 3, there is provided a valve 10 which makes it possible both for the second pump chamber 7 to be separated from the first pump chamber 3 and for the second pump chamber 7 to be connected to the first pump chamber 3. At the outlet 27 of the pump 2 there is arranged a valve 10 which has three different positions (a first valve position 36, a second valve position 37 and a third valve position 38), as has been discussed in more detail further above. The valve 10 may also be replaced by a combination of several conventional two-way valves and/or three-way valves.

(18) In the design variant of a pump 2 as per FIG. 7, a third pump chamber 25 is also provided in addition to the first pump chamber 3 and the second pump chamber 7. It is optionally additionally possible for a fourth pump chamber (not illustrated here) to be provided. Altogether, with the arrangement illustrated in FIG. 7, it is possible for any desired number of pump chambers to be provided for connection in parallel. The first pump chamber 3, the second pump chamber 7 and the third pump chamber 25 are connected by a drive shaft 5 to a rotary drive 4. Couplings 8 are provided in each case between the individual pump chambers, by which couplings the second pump chamber 7 and the third pump chamber 25 can be decoupled from the drive shaft 5. The first pump chamber is connected to a delivery duct 13. By valves 10, it is possible for connecting lines 33 to the second pump chamber 7 and to the third pump chamber 25 to be opened up in order to selectively permit parallel operation of the first pump chamber 3, of the second pump chamber 7 and of the third pump chamber 25. Depending on the delivery demand on the pump 2, the pump can be operated selectively with one pump chamber, with two pump chambers or with three pump chambers.

(19) FIG. 8 shows a motor vehicle 11 having an internal combustion engine 22 and having an exhaust-gas treatment device 12 for the purification of the exhaust gases of the internal combustion engine 22. In the exhaust-gas treatment device there is provided an SCR catalytic converter 24 by which nitrogen oxide compounds in the exhaust gas of the internal combustion engine can be reduced. For this purpose, a liquid additive can be fed to the exhaust-gas treatment device 12 by a feed device 20. Liquid additive is supplied from a tank 19 to the feed device 20 via a line 21 by a device 1. The motor vehicle 11 also has a control unit 23 by which the device 1 and the feed device 20 can be controlled.

(20) The invention described here makes it possible to realize a particularly advantageous device for supplying liquid additive, in which the delivery action of the device can be adapted in a particularly effective manner to the operating requirements of an exhaust-gas treatment device.

(21) Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.