EP2507489A1

EP2507489A1 - Delivery device for delivering a reducing agent

Info

Publication number: EP2507489A1
Application number: EP10787113A
Authority: EP
Inventors: Jan Hodgson; Sven Schepers
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Continental Automotive GmbH
Priority date: 2009-12-04
Filing date: 2010-12-03
Publication date: 2012-10-10
Also published as: US20120285147A1; WO2011067370A1; JP2013513056A; US10519831B2; JP6133600B2

Abstract

The invention relates to a delivery device (1) for delivering a reducing agent from a reducing agent tank (2) to an exhaust gas treatment device (3) of an internal combustion engine (4), comprising a partially rigid reducing agent line (5) and a delivery pump (6) arranged in the reducing agent line (5) and having a delivery direction (7) from the reducing agent tank (2) to the exhaust gas treatment device (3). The delivery device has at least one vibration compensating means (8) from the group consisting of: an inflow compensating means (9) in the delivery direction (7) upstream of the delivery pump (6); an outflow compensating means (10) in the delivery direction (7) downstream of the delivery pump (6); a pump-internal compensating means (11) within the delivery pump (6); and a structure-borne noise compensating means (13) on a fastening (14) of the delivery pump (6).

Description

Conveying device for conveying a reducing agent

The present invention relates to a conveying device for conveying a reducing agent from a reducing agent tank to an injector for supplying the reducing agent in an exhaust gas treatment device of an internal combustion engine. The exhaust of internal combustion engines regularly has substances whose emissions into the environment are undesirable. These can be removed with an exhaust treatment device.

Some methods of treating exhaust gases of an internal combustion engine in exhaust treatment devices require reducing agents to reduce certain pollutants in the exhaust gas that must be supplied to the exhaust gas. One of these methods is Selective Catalytic Reduction (SCR). Here, a selective reduction of the nitrogen oxide (NO _x ) takes place in the exhaust gas to molecular nitrogen (N ₂ ) using a reducing agent. One possible reducing agent is ammonia (NH ₃ ). Ammonia is often not stored in the form of ammonia, but rather an ammonia precursor is stored, which can be converted into ammonia if necessary. This is also referred to as a reducing agent precursor. An important reductant precursor that can be used in motor vehicles is urea ((NH ₂ ) ₂ CO). Preference is given to storing urea in the form of a liquid urea-water solution. Urea and in particular liquid urea-water solution is harmless to health, easy to distribute, store and portioned metered. Under the trade name "AdBlue", such a urea-water solution with a urea content of 32.5% is sold.

A urea-water solution is carried in a tank system in the motor vehicle and with an injection system with pump and injector portioned into the exhaust system. The consumption of urea for the reduction of undesirable nitrogen oxide compounds in the exhaust gas is up to 10% of the fuel consumption of the affected motor vehicle. For the portioned metered addition of reducing agent, it is necessary that the reducing agent be made available to an injector under a defined pressure. To generate this pressure, a pump is regularly provided in injection systems for reducing agent. Pulsating (stroke) working pumps have proven to be particularly suitable for this, because they are small, inexpensive and low maintenance.

The problem with such conveyors is regularly that they produce not insignificant noise in operation, which can be partially perceived by occupants of motor vehicles as disturbing true.

On this basis, it is an object of the present invention to alleviate the technical problems described in connection with the prior art. In particular, a conveyor device is to be disclosed which operates with particularly low noise.

These objects are achieved with a conveying device according to the features of patent claim 1. Further advantageous embodiments of the conveying device are specified in the dependent formulated patent claims. The features listed individually in the claims are combinable with each other in any technologically meaningful manner and can be supplemented by explanatory facts from the description, wherein further embodiments of the invention are shown.

Accordingly, a conveying device for conveying a reducing agent from a reducing agent tank into an exhaust gas treatment device of an internal combustion engine is proposed, which has a partially rigid reducing agent line and one in the Reduktionsmit- Having arranged in the exhaust line treatment device having a conveying device from the reducing agent tank arranged in the exhaust gas treatment device, wherein at least one Schwingungskomp ensationsmittel from the following group is present:

a feed compensation means in the conveying direction upstream of the feed pump,

an outlet compensation means in the conveying direction behind the feed pump,

a pump-internal compensation means within the delivery pump, and

a body of sound compensation means on a mounting of the feed pump.

Reducing agent here also means reducing agent precursor, from which the reducing agent can be produced. Inlet compensation means are provided in at least one of the following sections of the reducing agent line: upstream of the feed pump, in the feed line or in the feed line to the feed pump. Outlet compensation means are provided in at least one of the following sections of the reducing agent line: behind the feed pump, in the discharge line or in the discharge line from the feed pump. The drain line or discharge line is also referred to as a discharge line.

In the reduction agent line, it has been found that this should be at least partially rigid. Liquid urea-water solution can freeze, which is why the conveyor device according to the invention should be designed so that reducing agent can be frozen in it, without the conveyor is damaged and even in the presence of frozen reducing agent in the conveyor after a start of operation of the conveyor quickly reductant can be promoted again , At least partially rigid reductant lines can be routinely carried out with metallic walls having significant wall thicknesses above 0.5 mm. Such reducing agent lines are suitable for rapid heat input into the contained frozen reducing agents are particularly suitable, so that a rapid thawing is favored.

The delivery pump of the delivery device is preferably a pulsating delivery pump, in particular a piston pump or a diaphragm pump. Such a pump may have a working piston which is driven by an electromagnetic drive. Optionally, the working piston may be provided with a retaining spring, so that the electromagnetic drive moves the working piston against the retaining spring during each working stroke, and the working piston is then moved back again by a spring force of the retaining spring. In addition, a piston-diaphragm pump can be used, in which a membrane is driven by a transmission fluid via a transmission piston. It has been found that the delivery pump of the delivery device is the main source of the sound emitted by the delivery device, even if it interacts with rigid reductant lines. In pulsating pumps, a delivery piston is normally moved back and forth, for example, a membrane delivery pump. The delivery piston must be regularly accelerated and decelerated. In particular, if the acceleration or the deceleration takes place suddenly, for example because the delivery piston abuts against a stop, there is a shock, which is transmitted to the body as a structure-borne noise over the body of the feed pump and on the other hand perceptible as a flow pulse in the Reduktionsmittellei- direction and out of the pump.

In the context of the conveying device according to the invention, sound transmitted by a delivery pump can be compensated in at least one of the four different ways. An inlet compensation means and / or an outlet compensation means in the reducing agent line can mitigate or compensate for flow pulses in the (rigid) reducing agent line and at the same time prevent or reduce the transmission of structure-borne noise via the wall of the reducing agent line. Furthermore, a transmission of structure-borne noise on the attachment the pump can be prevented or reduced by suitable structure-borne noise compensation means on the attachment of the feed pump. In addition, it is also possible to provide pump-internal compensation means within the delivery pump, which keep the resulting sound in the pump from the outset low. Such "silencers" may, for example, also be provided in the manner of through-flowed perforated plates or the like and / or through-flow cross-sectional changes of the line, wherein these elements may optionally also be combined with one another and / or provided several times.

When an inlet compensation means and / or a Auslaufkompen- sationsmittel is taken into account that far more compensation of the sound transmission due to a flow pulse in the reducing agent line in the conveying direction behind the feed pump is required as before the feed pump. This is because the flow pulse of the feed pump is significant only in the conveying direction. Although it is also possible that on the suction side in the flow direction in front of the feed pump, a corresponding pressure surge occurs, but this is usually much smaller than the expelled from the pump pressure surge.

It is therefore particularly advantageous within the scope of the invention to dimension the intended outlet compensation means such that they have a volume which is at least 2 times as large, preferably 5 times as large and in particular at least 10 times as large as the volume of existing inlet compensation means , In some applications, it may also be useful to dispense entirely on inlet compensation means and / or the outlet compensation means to be dimensioned such that they are at least 20 times, preferably at least 50 times as large as the corresponding inlet compensation means. The conveyor device according to the invention is particularly advantageous if the conveying direction has at least one element from the following group:

- A metallic base plate in which at least partially the reducing agent line is formed and to which the feed pump is attached, and

- a metallic housing. Metallic components within the conveyor are regularly particularly well suited to transfer heat, so that the thawing behavior can be significantly improved by the use of metallic components when commissioning the conveyor in the frozen state. However, metallic components also transmit sound very well. This is due in particular to the high modulus of elasticity of such metallic components. For this reason, the provision of suitable compensation means in a conveyor device with corresponding metallic components is particularly advantageous. The conveyor device according to the invention is also particularly advantageous when the at least one feed compensation means comprises at least one element from the following group:

an O-ring seal in the reducing agent line,

a bellows filled with reducing agent,

- an air-filled bellows, and

an elastic reducing agent conduit section in the rigid reducing agent conduit.

By means of an O-ring seal in the reducing agent line, a fluid-tight interruption of the reducing agent line can take place, in particular in the case of a rigid metallic reducing agent line. As an alternative or in addition to an O-ring seal, it is also possible to provide a sleeve made of an elastic material, for example rubber, as feed compensation means. This sleeve can either be used as a Refraction of the rigid reducing agent line and / or be provided as a loaded element within a continuous rigid reducing agent line. It is also possible for a rigid reducing agent line (sections) to have an inner rubberized surface as compensating element. Such an interruption makes the transmission of structure-borne noise through the wall of the reducing agent conduit more difficult. A bellows filled with reducing agent can be embodied as part of the reducing agent line. For example, the wall of the reducing agent line by a corresponding formation in one piece contain such a bellows. It is essential with such a bellows that the volume filled with reducing agent is flexible. A dilution of the wall of the reducing agent line with respect to the remaining reducing agent line is thus a possibility. Furthermore, the reducing agent line in the area of the bellows can also be made of a more elastic material than in the other areas. Also, the use of an air-filled bellows is possible. Such a bellows should be made immediately adjacent to the reductant line so that it can be compressed in the presence of a surge within the reductant line so as to absorb the effects of the surge. Both in the filled with reducing agent as well as the air-filled bellows is a compensation of transmitted structure-borne noise also in that the walls are particularly thin in the region of the bellows, so that structure-borne noise can be transmitted only reduced. In a filled with air or other compressible medium bellows, it is possible to adjust the damping effect of the bellows on the air pressure in the bellows exactly. For example, the damping effect can be adjusted so that a sound compensation takes place below a certain sound level. A bellows can also be provided with a spring, which supports these, for example, against a rigid surface. So the behavior of the bellows can be influenced.

Moreover, it is also possible to provide an elastic reducing agent conduit section within the partially rigid reducing agent conduit. see. Although such an elastic reducing agent section at least partially contradicts the general design concept of the conveying device according to the invention with rigid reducing agent lines. However, a particularly effective compensation of the transmission of structure-borne noise from the delivery pump into the rest of the delivery device can be achieved by means of such a (small) elastic reducing agent conduit section in regions of the delivery pump. Especially in this area, the use of an elastic reducing agent line section is regularly particularly easy to implement because anyway a releasable connection between the feed pump and the rest of the conveyor should be realized. It is also possible to arrange the elastic reducing agent conduit section in such a way that it is in direct contact with a metallic wall, in particular a wall of a metallic housing, so that an effective heat input into the elastic reducing agent conduit section is possible.

Furthermore, according to the invention, the conveying device is when the at least one outlet compensation means comprises at least one element from the following group:

an O-ring seal in the reducing agent line,

a bellows filled with reducing agent,

an air-filled bellows,

a flow constriction,

a flow deflection,

an interference-generating surface, and

an elastic reducing agent conduit section in the rigid reducing agent conduit. In the outlet of the conveying device in the conveying direction behind the feed pump, in particular the compensation of the flow pulse in the reducing agent to compensate for the transmission of the sound from the feed pump into the rest of the conveying device is particularly important. The general effects of an O-ring seal in the reductant line, a bellows filled with reductant, an air-filled bellows, and a resilient reductant line section in the partially rigid reductant line have already been explained in the lead-in compensator explanation. These explanations are hereby fully incorporated by reference. The embodiments and modifications for these means, which are presented as feed compensation means, are also incorporated herein by reference in their entirety and are also applicable and transferable for discharge compensation means.

In addition, can be provided as Auslaufkompensationsmittel and a flow constriction. Such a flow restriction represents a flow resistance, via which a flow pulse in the reducing agent line is at least partially compensated. Also, a flow restriction creates a damping of the delivery piston of a feed pump, because only a limited amount of reducing agent can flow through a corresponding flow constriction, whereby the delivery speed of the feed pump is reduced. In a similar manner, a flow deflection, whereby additionally turbulence within the reducing agent flow can be achieved, which can at least partially lead to a reduction of the pressure surge acts. Further, it is also possible to provide an interference-generating surface through which corresponding deflection and turbulent flows are generated in the reducing agent, which also cause a reduction of the pressure surge. To generate interference, the discharge line can also be shaped in the manner of a worm. A screw is particularly suitable for generating interference in the flow of reducing agent emerging from the delivery pump. The screw can be shaped so that sound waves run dead inside.

In the reducing agent line, a flow pulse on the wall is at least partially converted into structure-borne noise. Based on these Conversion, it is particularly advantageous as discharge compensating both provide a compensation for flow pulses particularly suitable compensation means and a compensation of structure-borne noise particularly suitable compensation means. For compensating the flow pulse, bellows or flow constrictions or flow deflections filled with reducing agent and / or air are particularly suitable. The transmission of structure-borne noise via a reducing agent line can be achieved particularly well by a mechanical division of the reducing agent line. Here, an O-ring seal is particularly suitable. It is therefore particularly advantageous to provide as outlet compensation means an O-ring seal in combination with a bellows filled with air or reducing agent or a flow constriction or flow diversion. In the flow direction, the compensating means for compensating the flow pulse should first be provided in order to prevent an uncontrolled transmission of the sound as a flow pulse. Subsequently, the compensation means should be provided to compensate for structure-borne noise in order to effectively prevent the transmission of structure-borne noise. To realize a Zulaufkompensationsmittel or a discharge compensating means, the supply line and the discharge line can be made of plastic. For example, a rubber hose can be used as a supply line or as a discharge line. Also particularly advantageous are multi-layer feed lines and discharge lines. The properties of such lines, and in particular the elasticity and the thermal conductivity, can be particularly well dimensioned specifically for multilayer lines. If the supply line or the discharge line is made of plastic, metal mesh or metal flags can be incorporated in this plastic. It is also possible to carry out the supply line or the outlet line with a phase change material.

If the conveyor device has a metallic base plate, it may be necessary to connect the feed line or the outlet line to the metal plate. metallic base plate (detachable / permanent). This connection must produce a sufficiently pressure-tight fluidic connection between the metallic base plate and the feed line or the discharge line.

The connection of the supply line or the discharge line to a base plate of the conveyor can be done with the aid of an elastic adhesive. Next, the connection can be made cohesively, for example by welding. It is also possible to perform the attachment using a hose clamp. This is particularly advantageous if the supply line or the discharge line comprises a rubber hose. To connect the supply line or the discharge line, a (cylindrical) plastic sleeve, or rubber sleeve can be used, which is used as an intermediate piece for sealing between the inlet line or the outlet pipe and the base plate. The plastic sleeve can be designed so that it forms a plurality of annular sealing surfaces with the base plate and / or the supply line or the discharge line. Preferably, the plastic sleeve has on its outer surface and / or on its inner surface a plurality of circumferential bead-like elevations, which form the sealing surfaces. Furthermore, it is also possible for the plastic sleeve to have a flat surface at least in some areas and to provide annular sealing projections on the supply line, the outlet line or the base plate for sealing with the plastic sleeve, which form the sealing surfaces together with the flat surface.

The delivery device is also preferred if the at least one pump-internal compensation means is provided inside the delivery pump and at least one element from the following group comprises:

an elastic stop,

a choked plot, and

an elastic transfer fluid. Providing an internal pumping means within the delivery pump is particularly effective because it can be minimized or prevented in this way directly at the source of the sound. By reducing the flow pulse triggered by the delivery pump, it is also possible to prevent the flow pulse from producing structure-borne noise in other regions of the delivery device.

A pulsating working pump has - as already stated - regularly on a reciprocating delivery piston. This delivery piston acts either directly on the fluid to be delivered or is separated from this fluid by a membrane. Then usually a transfer fluid is provided, which transfers the forces of the delivery piston particularly gently on the membrane. In this way, contact between the fluid to be pumped, here reducing agent, and the mechanics of the feed pump can be prevented. This is particularly advantageous because reducing agent regularly acts particularly corrosive and the mechanics of the feed pump could be damaged by the contact with reducing agent. Likewise, external spring elements and / or damping elements can be provided, which influences a movement / vibration, etc. of the (entire) pump relative to the lines, in particular reduced or even prevented.

Particularly problematic for the formation of structure-borne noise or the pressure surge is the sudden deceleration of the delivery piston after carrying out a conveying movement. This can be at least partially prevented for example by an elastic stop, which yields when the delivery piston strikes. Furthermore, a throttled stop can also be provided, in which, shortly before completion of the delivery stroke, a quantity of fluid has to be transported through a restricted passage, whereby a significant flow resistance is created, which slows down the delivery piston. In addition, it is also possible to provide an elastic conveying fluid. Although the deceleration of the delivery piston is then jerky, the transfer fluid is compressed by the movement of the delivery piston and expands in time. emanates, so that no special pressure surge is generated in the reducing agent to be pumped.

The measures proposed here can also represent a development of a pump independently of the conveying device.

Also according to the invention, the conveying device, if the at least one structure-borne sound compensation means is present on a mounting of the feed pump and at least one element from the following group comprises:

an elastic attachment of the feed pump,

a cross-sectional reduction at the attachment of the feed pump, and a resilient suspension of a base plate to which the feed pump is attached.

By an elastic attachment of the feed pump, a transmission of structure-borne noise from the feed pump to the component to which the feed pump is attached, typically the base plate of a conveyor, reduced or prevented. It is advantageous to carry out such an elastic attachment of the feed pump from a different material than the feed pump or the base plate. For example, the elastic attachment can be realized by a block of plastic, in which case in addition a suitable thermal bridge can be provided by the feed pump to the metallic base plate. A cross-sectional reduction of the attachment of the feed pump reduces the available for the transmission of structure-borne sound cross-section of the feed pump to the corresponding component to which the feed pump is attached. This also prevents or reduces the transmission of body sound.

It is also possible to attach the component to which the feed pump is attached, in particular a base plate, to an elastic suspension. If in addition an elastic attachment of the feed pump and / or a corresponding cross-sectional reduction at the attachment the delivery pump is provided, the metallic base plate acts as an additional damping element, which is set in counter vibrations to the feed pump and thus effectively compensates the movement of the feed pump. A transmission of structure-borne noise beyond the base plate can be effectively prevented.

In addition and / or as an alternative to the described compensation measures, it is also possible to implement structure-borne noise and sound transmission from a conveying device with the aid of control-technical or procedural compensation measures. In particular, a method for operating a conveying device for conveying a reducing agent from a reducing agent tank into an exhaust gas treatment device of an internal combustion engine, comprising a partially rigid reducing agent line and a conveying pump arranged in the reducing agent line with a conveying direction, comprising at least one of the following steps:

Interception of pressure peaks,

gentle deceleration of a delivery piston of the feed pump, and gentle acceleration of a delivery piston of the feed pump.

As already stated for the conveying device according to the invention, the sound generated by the conveying device essentially depends on the flow pulse produced by the conveying movement and the associated pressure peaks.

In the context of the described method it is possible to cut off precisely these pressure injections. Regularly, conveying devices for reducing agents have a return valve, through which the pumped reducing agent can pass out of the conveying device back into the reducing agent tank. Such return valves are regularly arranged in the conveying direction behind the feed pump and can be set up so that they at pressure peaks, the z. B. a certain pressure threshold above 8 bar, in particular above reach of 10 bar and more preferably above 12 bar, open and the pressure peak is capped.

Furthermore, a gentle (reduced) deceleration of a delivery piston of the delivery pump or a gentle (reduced) acceleration of a delivery piston of the delivery pump can also take place. This can be realized in particular by control measures. For example, the current for operating an electromagnetic drive of the delivery piston for decelerating and accelerating the delivery piston can each be (continuously) increased and reduced so that the delivery piston is gently braked or accelerated respectively. It is also possible that a (local and / or temporally limited) opposite polarity of the (electromagnetic) drive takes place in order to achieve a rapid influence on the delivery piston. Also, an additional coil may be provided which can decelerate the delivery piston.

Also, an active compensation of sound can be done. For example, it is possible to provide counter speakers in the conveyor. Loudspeakers that work in the ultrasound field can also be used for this purpose.

The invention is particularly advantageous in a motor vehicle, comprising an internal combustion engine and an exhaust system with at least one exhaust gas treatment device adapted for selective catalytic reduction and a conveying device according to the invention.

Also according to the invention is a motor vehicle with the conveying device, which is set up for carrying out a method according to the invention.

The advantages and special configurations embodied for the conveying device according to the invention can be applied and transferred in an analogous manner to the method described here. The same parts and special features and embodiments of the method are transferred to the conveyor device according to the invention.

The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. It should also be pointed out that the figures, in particular illustrated proportions, are only schematic. 1 shows a first embodiment of a conveying device according to the invention,

2 shows a second embodiment of a conveyor device according to the invention,

3 is a top view of a third embodiment of a conveyor device according to the invention,

4 shows a partial side view of a fourth embodiment variant of a conveying device according to the invention,

5 shows a detail of a feed pump for a conveying device according to the invention, FIG. 6 shows a motor vehicle comprising a conveying device according to the invention, and FIG

FIG. 7 shows a variant of a structure-borne sound compensation medium. FIG.

Figures 1 and 2 show a first and a second embodiment of a conveyor device according to the invention 1. The conveyor device 1 according to the invention comprises a metallic base plate 16 and a feed pump 6. The feed pump 6 is connected via a reducing agent line 5 is connected to the metallic base plate 16. In the metallic base plate 16 at least one channel 39 is provided, via which a further line of the reducing agent can be made to other components of the conveying device 1, not shown here. The reducing agent is conveyed by the feed pump 6 and the reducing agent line 5 with the conveying direction 7.

According to FIGS. 1 and 2, various vibration compensation means 8 are provided, which will be explained in detail below.

In Fig. 1, a Zulaufkompensationsmittel 9 is provided, which is designed as an O-ring seal 17. In addition, a discharge compensation means 10 is provided, which is designed as a bellows filled with reducing agent 18. Here, a simple corrugation of the wall of the reducing agent line 5 is shown, through which an expansion of the reducing agent volume in the reducing agent line 5 is possible. In addition, an interference-generating surface 22 is provided as the outlet compensation means 10. This interference-generating surface 22 can be embodied, for example, as a pyramid oriented counter to the conveying direction 7, through which a returning wave forms in the reducing agent flow, which generates an at least partial extinction of a pressure pulse in the reducing agent flow. Furthermore, a flow constriction 21 is provided as outlet compensation means 10, the mode of action of which has already been explained in detail. Finally, a structure-borne noise compensation means 13 for preventing the transmission of structure-borne noise from the feed pump 6 to the metallic base plate 16 is also provided. This structure-borne sound compensation means 13 is embodied within the attachment 14 of the feed pump 6 as an elastic attachment 29. Here too, further explanatory information has already been provided.

2, an O-ring seal 17 is also shown as Zulaufkompensationsmittel 9. As a discharge compensation means 10, an air-filled bellows 18 is provided, which upon occurrence of a Strö- mungspulses from the feed pump 6 can be compressed and thus leads to an elastic change in the volume within the reducing agent line 5. The elastic bellows is delimited by the reducing agent through a membrane. In addition, a flow deflection 20 is provided as outlet compensation means 10, the mode of action of which has likewise already been explained in detail. As body sound compensation means 13, a cross-sectional reduction 30 is provided here in the region of the attachment 14 of the delivery pump 6 on the metallic base plate 16.

The illustrated in Fig. 3 view of a third embodiment of a conveyor device 1 according to the invention also shows a metallic base plate 16 to which a feed pump 6 is fixed and beyond a metallic housing 15 of the conveyor device 1. The connection of the feed pump 6 to the metallic base plate 16 via reducing agent lines 5. Reducing agent is conveyed by the feed pump 6 and the reducing agent line 5 with the conveying direction 7. The distribution of the reducing agent to other components of the conveyor device 1 via channels 39 within the metallic base plate 16. As further components here a filter 36 and a return valve 38 are shown. In the embodiment according to FIG. 3, a run compensating means 10 designed as an elastic reducing agent line section 19 is provided as the vibration compensation means 8. This elastic reducing agent line section 19 is completely guided once along the metallic housing 15 of the conveyor device 1. As a result, on the one hand, the position of the elastic reducing agent conduit section 19 is possible in a particularly space-saving manner. On the other hand, a relatively long elastic reducing agent conduit section 19 may be provided. The elastic reducing agent conduit section 19 also bears against the metallic housing 15, so that good heat transfer is possible here. By the length and the circular guidance of the elastic reducing agent line section 19, on the one hand, a particularly good compensation of a pressure pulse is achieved. At the same time, such a long elastic reducing agent 19 also a flexible volume for reducing agent, which acts like a bellows. Furthermore, a structure-borne sound compensation means 13 in the region of the attachment 14 of the feed pump 6 to the metallic base plate 16 is provided as vibration compensation means 8. This body sound compensation means 13 is designed as an elastic attachment 29.

Fig. 4 shows a partial side view of a conveyor device according to the invention 1. Again, the metallic housing 15 and the metallic see base plate 16 can be seen. On the metallic base plate 16, the feed pump 6 can be seen with the reducing agent lines 5, through which reducing agent can be promoted with the conveyor 7. As Schwingungskomp insensing means 8 4 only a structure-borne noise compensation means 13 is provided as shown in FIG., Which is realized as an elastic suspension 31 of the metallic base plate 16 in the metallic housing 15. In FIG. 4, structure-borne noise compensation means 13 are also shown in the manner of a vibration compensation means 8. These structure-borne sound compensation means 13 are a system of springs 44 and dampers 45, by which the feed pump 6 is fixed to the metallic base plate 16. Such a structure-borne noise compensation means 13 consists of at least one spring 44 and at least one damper 45. By a suitable choice of the spring constant of the springs 44 and the damping constant of the damper 45, the body sound compensation means 13 can be adjusted so that it individual from the feed pump generated vibration frequencies and / or entire oscillation frequency ranges particularly well compensated.

Fig. 5 shows a detail of a feed pump 6. The feed pump 6 operates pulsatile. It has a pumping chamber 35, through which reducing agent can be conveyed with a conveying direction 7. The conveying direction 7 is predetermined by two valves 34. The volume of the pumping chamber 35 is regularly increased and decreased by a membrane 33. The force released by the delivery piston 27 is transmitted to the membrane via a transfer fluid 25. The delivery piston 27 is of a drive 42 driven. Such a drive 42 has an electromagnetic drive with a coil. The transfer fluid 25 may be elastic in order to reduce the flow pulse triggered by the delivery piston 27. As a vibration compensation means 8, an elastic stop 23 may be provided as a pump-internal compensation means 11. The elastic stop 23 may alternatively or simultaneously be a throttled stop 24. When the delivery piston 27 moves into its end position on the elastic stop 23 or on the elastic stop 24, it is slowly decelerated either by an elastic return of the elastic stop 23 or by a throttle effect for the transfer fluid 25 of the throttled stop 24, so that no sound generating flow pulse arises. To favor a throttling effect of a throttled stop 24, a projection 41 can be provided on the delivery piston 27 of a delivery pump 6, which promotes the throttling effect by providing a narrow gap between throttled stop 24 and projection 41 shortly before completion of a delivery stroke of the delivery piston 27. Optionally z. As well as a brake coil 43 may be provided which can exert an electromagnetic counter-pulse on the delivery piston 27, so that the delivery piston 27 is braked not suddenly, but damped. It is also possible that the drive 42 is reversed to decelerate the delivery piston 27, the drive 42 thus itself exerts a counter-pulse on the delivery piston 27 to its deceleration. FIG. 6 shows a motor vehicle 32 comprising an internal combustion engine 4, an exhaust gas treatment device 3 and a conveyor device 1 according to the invention. The exhaust gas treatment device 3 is arranged within an exhaust system 28 of the internal combustion engine 4. The conveying device 1 conveys reducing agent with a conveying direction 7 from a reducing agent tank 2 to an injector 40, via which the reducing agent is introduced into the exhaust system 28 or the exhaust gas treatment device 3. Along the reducing agent line 5, the conveying device 1 has a filter 36, a feed pump 6 and a pressure sensor 12. Furthermore, in the reducing agent line 5 in the conveying direction 7 behind the feed pump 6, a return line 37 is provided back into the reducing agent tank 2, through which superfluous reducing agent can be returned to the reducing agent tank 2. The return line 37 has a return valve 38, by which a flow pulse of the reducing agent in the reducing agent line 5 can be intercepted. Such a flow pulse can be done automatically by a mechanical opening at overpressure of the return valve 38. But it is also possible to determine such a flow pulse via the pressure sensor 12 and to open the return valve 38 accordingly. The operations in the conveyor 1 may be controlled by a controller 26 which communicates with the essential components of the conveyor 1. Within such a controller 26, the described methods for compensation of sound and flow pulse within the conveyor device 1 can also be implemented.

FIG. 7 shows another vibration compensation means 8 embodied as structure-borne noise compensation means 13. The delivery pump 6 is fastened to the metallic base plate 16 by means of spring plates 46 which are perpendicular to the metallic base plate 16. In addition, a damper 45 is provided. The spring plates 46 have a spring constant and the damper 45 has a damping constant. By a suitable choice of these constants, the system can be set exactly to compensate for certain generated by the feed pump 6 vibration frequencies or even vibration frequency ranges. LIST OF REFERENCE NUMBERS

I conveyor device

2 reducing agent tank

3 exhaust treatment device

4 internal combustion engine

5 reducing agent line

6 feed pump

7 conveying direction

8 vibration compensation means

9 Inlet compensation agent

10 outlet compensation means

I I pump internal compensation means 12 Pressure sensor

13 structure-borne sound compensation agents

14 attachment

15 metallic housing

16 metallic base plate

17 O-ring seal

18 bellows

19 elastic reducing agent line section

20 flow deflection

21 flow restriction

22 interference generating surface

23 elastic stop

24 throttled stop

25 transfer fluid

26 control

27 delivery piston

28 exhaust system

29 elastic attachment

30 Cross-section reduction

31 elastic suspension Motor vehicle diaphragm valve

Pump chamber filter

Return line return valve channel

Injector projection drive

Brake coil spring

Damper spring plate

Claims

claims

Conveying device (1) for conveying a reducing agent from a reducing agent tank (2) into an exhaust gas treatment device (3) of an internal combustion engine (4) comprising a partially rigid reducing agent line (5) and a conveying pump (6) arranged in the reducing agent line (5) with a conveying direction ( 7) from the reducing agent tank (2) in the exhaust gas treatment s ago direction (3), wherein at least one Schwingungskompensa- tion means (8) from the following group is present:

- An inlet compensation means (9) in the conveying direction (7) in front of the feed pump (6);

- A discharge compensation means (10) in the conveying direction (7) behind the feed pump (6);

- In-pump compensation means (11) within the feed pump (6); and

- A structure-borne sound compensation means (13) on a fastening (14) of the feed pump (6).

Conveying device (1) according to claim 1, wherein the conveying device (1) comprises at least one element from the following group:

- A metallic base plate (16) in which at least partially the reducing agent line (5) is formed, and on which the feed pump (6) is fixed; and

- A metallic housing (15). Conveying device (1) according to one of the preceding claims, wherein the at least one inlet compensating means (9) comprises at least one element from the following group:

- An O-ring seal (17) in the reducing agent line (5);

- A filled with reducing agent bellows (18);

- an air-filled bellows (18); and

- An elastic reducing agent line section (19) in the rigid reducing agent line (5).

Conveying device (1) according to one of the preceding claims, wherein the at least one outlet compensation means (10) comprises at least one element from the following group:

- An O-ring seal (17) in the reducing agent line (5);

- A filled with reducing agent bellows (18);

- an air-filled bellows (18);

a flow s constriction (21);

- A flow deflection (20);

an interference generating surface (22); and

Conveyor device (1) according to one of the preceding claims, wherein the at least one pump-internal compensation means (11) is provided inside the feed pump (6), and at least one element from the following group comprises:

- An elastic stop (23);

- a throttled stop (24); and

- An elastic transfer fluid (25). Conveyor device (1) according to one of the preceding claims, wherein the at least one structure-borne sound compensation means (13) is present on a mounting (14) of the feed pump and comprises at least one element from the following group:

- An elastic attachment (29) of the feed pump (6);

- A cross-section reduction (30) on the attachment (14) of the feed pump (6); and

- An elastic suspension (31) of a base plate (16) on which the feed pump (6) is attached.

A motor vehicle (32) comprising an internal combustion engine (4) and an exhaust system (28) having at least one exhaust gas treatment device (3) adapted for selective catalytic reduction and a conveying device (1) according to one of the preceding claims.