Abstract
A conveying unit for conveying reducing agent from a tank to an exhaust gas treatment device for treating the exhaust gases from an internal combustion engine, includes a pump having a drive or drive unit and a pump chamber unit or containment. The pump chamber unit or containment at least partly delimits a pump chamber and the drive or drive unit and the pump chamber unit or containment are detachable from one another.
Claims
1. A conveying unit for conveying reducing agent from a tank to an exhaust gas treatment device for treating exhaust gases from an internal combustion engine, the conveying unit comprising: a pump having a drive and a pump chamber containment; said drive and said pump chamber containment being detachably interconnected; said pump chamber containment at least partly delimiting a pump chamber; and a controller configured to operate said pump for a test run with minimal driving power to determine if frozen reducing agent present in the conveying unit is impeding operation of said pump.
2. The conveying unit according to claim 1, which further comprises a flange, said drive being fastened to said flange, and said pump chamber containment being at least partly formed by said flange.
3. The conveying unit according to claim 1, which further comprises a pump diaphragm separating said pump chamber containment and said drive.
4. The conveying unit according to claim 3, wherein said pump chamber containment is constructed in the form of a half shell and said pump chamber is delimited by said pump chamber containment and by said pump diaphragm.
5. The conveying unit according to claim 1, wherein said pump chamber has a chamber volume configured to be reduced during a pumping procedure to a dead volume, and said dead volume is less than 20% of said chamber volume.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) FIG. 1 is a diagrammatic, vertical-sectional view of a variant of a conveying unit according to the invention;
(2) FIG. 2 is a vertical-sectional view of a first variant of a pump of a conveying unit according to the invention;
(3) FIG. 3 is a vertical-sectional view of a second variant of a pump of a conveying unit according to the invention;
(4) FIG. 4 is an elevational view of a pump chamber unit for a pump of a conveying unit according to the invention;
(5) FIG. 5 is a sectional view of the pump chamber unit according to FIG. 4;
(6) FIG. 6 is an elevational view of a valve for a pump for a conveying unit according to the invention;
(7) FIG. 7 is a sectional view of the valve according to FIG. 6;
(8) FIG. 8 is a block diagram of a motor vehicle having a conveying unit according to the invention;
(9) FIG. 9 is a graph illustrating speeds of a rotary drive and of a movable pump element;
(10) FIG. 10 is a sectional view of a pump for a conveying unit according to the invention;
(11) FIG. 11 is a longitudinal-sectional view of a flange of a conveying unit according to the invention;
(12) FIG. 12 is an enlarged, fragmentary, sectional view of a portion XII of FIG. 11;
(13) FIG. 13 is a first enlarged, exploded, perspective view of FIG. 11;
(14) FIG. 14 is a second enlarged, exploded, perspective view of FIG. 11;
(15) FIG. 15 is a longitudinal-sectional view of a flange of a conveying unit according to the invention;
(16) FIG. 16 is an enlarged, fragmentary, sectional view of a portion B of FIG. 15;
(17) FIG. 17 is an enlarged, fragmentary, sectional view of a portion C of FIG. 15;
(18) FIG. 18 is a first enlarged, exploded, perspective view of FIG. 15; and
(19) FIG. 19 is a second enlarged, exploded, perspective view of FIG. 15.
DESCRIPTION OF THE INVENTION
(20) Referring now in detail to the figures of the drawings, which show particularly preferred embodiments to which the invention is not limited and in which dimensions are merely diagrammatically illustrated and first, particularly, to FIG. 1 thereof, there is seen a conveying unit 1 having a flange 12. Various components of the conveying unit 1 are mounted on the flange 12. According to FIG. 1, for example, a drive or drive unit 10 for a pump 8 is fixed on the flange 12. In addition to the drive unit 10, the pump 8 includes a pump chamber unit or containment 11. The pump chamber unit 11 is a constituent of the flange 12. A pump chamber 9 is located in the pump chamber unit or containment 11. A conveyance path 7 through the conveying unit 1 extends from an inlet fitting 5 through the pump chamber 9 in the pump chamber unit 11 to an outlet fitting 6.
(21) FIG. 2 is a detailed view of a first variant of the pump 8 showing the drive unit 10 and the pump chamber unit or containment 11. The drive or drive unit 10 includes a motor 28 which drives an eccentric member 30 through a gear 29. The motor 28, the gear 29 and the eccentric member 30 together form a rotary drive 20. A movement of the eccentric member 30 is transferred through a transfer element or converter 22 to a movable pump element 21. In the transfer element 22 there can optionally be provided a smoothing device 23 through which a conversion of a rotational movement of the rotary drive 20 into a linear movement of the movable pump element 21 can be smoothed. The pump chamber 9 can initially be seen in the pump chamber unit 11. The pump chamber 9 is formed of a principal compartment 14 and a spur duct 15. An arrow in the spur duct 15 indicates how the reducing agent flows into the pump chamber 9 during intake and flows out of the pump chamber 9 during discharge, alternately in different respective directions in the spur duct 15. An inlet valve 16 and an outlet valve 17 adjoin the spur duct 15. The inlet valve 16 and the outlet valve 17 are preferably identical in construction. The path 7 for the conveyance of reducing agent through the pump 8 extends from the inlet valve 16 through the spur duct 15 into the principal compartment 14 of the pump chamber 9 and back through the spur duct 15 and the outlet valve 17. The inlet valve 16 and the outlet valve 17 are inserted into a corresponding passage in the pump chamber unit 11.
(22) In a second variant of the pump 8 shown in FIG. 3, the illustration focuses on aspects which are different from FIG. 2. In this case, the pump chamber 9 is merely shown diagrammatically. A smoothing device 23 disposed on the transfer element 22 for smoothing the transfer of the rotational movement of the rotary drive 20 into the linear movement of the movable pump element 21, is not illustrated either. Instead, a pressure sensor 31 is illustrated which adjoins the conveyance path 7 through the pump 8. The pressure in the conveyance path downstream of the pump 8 can be established by this pressure sensor 31. The pressure measured by the pressure sensor 31 can be evaluated in a controller 32 so that the rotary drive 20 of the pump 8 is controlled so as to cause the rotational movement of the rotary drive 20 to take place in such a way that the linear movement of the movable pump element 21 is linear at least in some regions or in part. The controller 32 may be configured or programmed to operate the pump 8 for a test run with minimal driving power in order to determine if frozen reducing agent in the conveying unit 1 is impeding operation of the pump 8. FIG. 3 also shows that the drive unit 10 includes a housing 33 which is open on one side and sealed on the pump chamber unit 11 by a seal 34. The pump chamber unit 11 can be a constituent of a flange of the conveying unit 1 according to the invention. The housing 33, which is open on one side, can thus cover further components such as the pressure sensor 31, the controller 32 or also a temperature sensor (which is not shown herein) in addition to the rotary drive 20 of the pump 8. These components need not be direct constituents of the pump 8. The pump 8 and further components of the conveying unit 1 according to the invention can thus be integrated with one another.
(23) FIG. 4 is a view of a pump chamber unit or containment 11 for a pump 8 of a conveying unit 1 according to the invention, showing the principal compartment 14 of the pump chamber 9. The spur duct 15 branches from the principal compartment 14. The inlet valve 16 and the outlet valve 17 adjoining the spur duct 15 are shown in broken lines below the principal compartment 14.
(24) The principal compartment 14 and the spur duct 15 forming the pump chamber 9 are shown in section in FIG. 5. The manner in which the inlet valve 16 and the outlet valve 17 adjoin the spur duct 15 is also shown. A pump diaphragm 13 which limits the pump chamber 9 is additionally shown. A chamber volume 37 which exists when a movable pump element 21 is at a upper return point is shown in broken lines. The chamber volume 37 corresponds to a maximum volume occurring in the pump chamber 9 during conveyance. A dead volume 36, which corresponds to a minimum volume of the pump chamber 9 during conveyance, is also indicated. This dead volume 36 exists in the pump chamber 9 when the movable pump element 21 is located at its lower return point. FIG. 5 also shows a length 35 of the spur duct 15 from the principal compartment 14 of the pump chamber 9 to the inlet valve 16 and to the outlet valve 17. A cross-section 38 of the spur duct 15 is further indicated in broken lines.
(25) FIG. 6 shows an inlet valve 16 which may be used in a particularly advantageous manner in the conveying unit 1 according to the invention.
(26) A valve corresponding to the illustrated inlet valve 16 can also be used as an outlet valve 17. The inlet valve 16 includes a base body 18 which is rotationally symmetrical. The valve ducts and mechanism are indicated in broken lines in the base body 18. The base body 18 has a circumferential connecting duct 19 which communicates with internal ducts in the inlet valve 16. An inlet valve 16 of this type may be positioned as desired in a passage in a pump chamber unit 11 of a conveying unit 1 according to the invention and, through the use of the circumferential duct, can produce a connection to a channel which opens laterally into the passage.
(27) In order to clarify the illustration in FIG. 6, FIG. 7 shows a further section through the inlet valve 16 in FIG. 6.
(28) FIG. 8 shows a motor vehicle 27 including an internal combustion engine 4 and an exhaust gas treatment device 3 for cleaning exhaust gases from the internal combustion engine 4. The motor vehicle 27 includes a tank 2 for storing reducing agent. The reducing agent can be conveyed from the tank 2 through an intake pipe 24 to a conveying unit 1. The conveying unit 1 then conveys the reducing agent through an outlet pipe 25 to an injector 26 which feeds the reducing agent to the exhaust gas treatment device 3.
(29) FIG. 9 shows a graph of speeds of a rotary drive 20 and a movable pump element 21. The speed of movement of the rotary drive 20 is illustrated by a dotted line whereas the speed of the movable pump element is illustrated by a continuous line. The two bold lines belong together as do the two faint lines. The movement of the rotary drive 20 is transferred to the movable pump element 21 in this case by using a respective transfer element 22 which does not have a smoothing device 23. The speeds are plotted on a speed axis 46 with respect to time axis 47 in each case. According to the bold dotted line, the rotary drive 20 is operated at a constant speed. This produces the sinusoidal speed of movement of the movable pump element 21 corresponding to the bold continuous line. According to the faint dotted line, the rotary drive 20 is operated at a regularly varying speed. The rotary drive 20 is driven faster in some regions in order to linearize the movement of the movable pump element 21 at least in some regions, as can be inferred from the faint continuous line showing the speed of the movable pump element 21 produced when the rotary drive is driven in accordance with the faint dotted curve. However, complete linearization is not possible, in particular in the region of the reversals of the direction of movement of the movable pump element 21 at the upper return point and at the lower return point. In order for that to occur, it would in fact be necessary for the rotary drive 20 to be operated at extremely high speeds.
(30) FIG. 10 shows an example of a smoothing device 23 on the transfer element 22, illustrating a pump 8 for a conveying unit 1 according to the invention with a rotary drive 20. The movement of the rotary drive 20 is transferred to the movable pump element 21 through the transfer element 22. The transfer element 22 is constructed as a camshaft or as a cam disc. The smoothing device 23 is produced by configuring the pitch or circumferential contour or course of the camshaft or of the cam disc in such a way that the movement of the movable pump element 21 is uniform, at least in some regions, during uniform movement of the rotary drive 20. The movable pump element 21 is moved back and forth between an upper return point 48 and a lower return point 45. The pump chamber 9, the volume of which is increased and decreased by the movement of the movable pump element 21, is merely diagrammatically indicated.
(31) FIG. 11 shows a flange 12 for a conveying unit 1 with a few accessories. For example, the outlet fitting 6 can be seen.
(32) FIG. 12 shows an enlarged portion of FIG. 11 which is designated by reference numeral XII in FIG. 11. A duct 40 can be seen, through which the conveyance path of the conveying unit 1 extends. A pressure sensor 31 is disposed on the duct 40 and a biased ice pressure compensation device 39 is mounted on the flange 12.
(33) FIG. 13 is an exploded view of the flange 12 according to FIG. 11. It can be seen how the biased ice pressure compensation device 39 is mounted on the flange 12 through a first diaphragm 41. The outlet fitting 6 is also shown in FIG. 13 for orientation purposes. It can also be seen from FIG. 13 that the duct 40 in the flange 12 may also be located on the surface of the flange 12. The duct 40 is then closable by an accessory 42 which is sealed against the flange 12 by an O-ring seal 43.
(34) It is possible to see from FIG. 14 how a temperature sensor 44 and the pressure sensor 31 are attached to the flange 12. The O-ring seal 43 is additionally provided on the flange 12, surrounds the temperature sensor 44 and the pressure sensor 31, and can be used to form a splash-proof seal between the flange 12 and a cover (which is not shown therein). This cover may be formed by a pump head (which is not shown). A pump chamber 9 can also be seen in FIG. 14. The pump chamber 9 is a constituent of the flange 12. A pump diaphragm 13 can be placed over the pump chamber 9. This pump diaphragm 13 can be moved by the drive unit 10 (which is also not shown therein but is shown in FIG. 2) in order to convey reducing agent. The drive unit 10 is preferably disposed in the pump head (which is not shown).
(35) FIG. 15 is a further sectional view through a conveying unit 1 according to the invention with a flange 12. Details of the illustration in FIG. 15 are shown in FIGS. 16 and 17.
(36) FIG. 16 shows the inlet valve 16 and the outlet valve 17 of the pump 8 of the conveying unit 1 which are inserted into the flange 12 through a passage. The inlet valve 16 and the outlet valve 17 are biased in the passage by a resilient element constructed as a spring. The inlet valve 16 and the outlet valve 17 are thus movable when the pressure in the conveying unit 1 exceeds a threshold pressure. A biased ice pressure compensation element 39 is thus formed. The inlet valve 16 and the outlet valve 17 communicate with the pump chamber 9 through the spur duct 15.
(37) FIG. 17 illustrates the outlet fitting 6, which is also fixed by a spring-loaded element constructed as a spring in a passage in the flange 12. The outlet fitting 6 is thus also movable when the pressure in the conveying unit 1 exceeds a threshold pressure. A biased ice pressure compensation element 39 is thus also formed on the outlet fitting 6.
(38) FIGS. 18 and 19 are respective exploded views, showing how the inlet valve 16 and the outlet valve 17 or the outlet fitting 6 are inserted into the flange 8. The pump chamber 9 formed on the flange 12 can also be seen.
