EP3120025A1

EP3120025A1 - Pump for conveying a liquid, in particular an exhaust-gas cleaning additive

Info

Publication number: EP3120025A1
Application number: EP15710204.7A
Authority: EP
Inventors: Jan Hodgson; Georges Maguin; Yves KOPP
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2014-03-19
Filing date: 2015-03-18
Publication date: 2017-01-25
Also published as: US20170016444A1; US10294937B2; WO2015140201A1; CN106068367B; CN106068367A

Abstract

The invention relates to a pump (1) for conveying a liquid, comprising at least one pump housing (2), which has at least one inlet (3) and at least one outlet (4) and an inner circumferential surface (13) and a geometric axis (53), wherein an eccentric (5), which can be rotated about the geometric axis (53) in relation to the pump housing (2), is arranged within the pump housing (2), wherein a deformable element (7) is arranged between the inner circumferential surface (13) of the pump housing (2) and the eccentric (5) and wherein a conveying channel (8) from the at least one inlet (3) to the at least one outlet (4) is formed by means of the deformable element (7) and the inner circumferential surface (13) of the pump housing (2) and wherein furthermore the deformable element (7) is pressed against the pump housing (2) by the eccentric (5) in some sections in such a way that at least one movable seal (9) of the conveying channel (8) and at least one closed pump volume (10) in the conveying channel (8) are formed, which at least one seal and at least one closed pump volume can be moved in order to convey the liquid along the conveying channel (8) from the inlet (3) to the outlet (4) by means of a rotational motion of the eccentric (5), wherein at least one receptacle (14), in which at least one edge region (20) of the deformable element (7) is accommodated, is formed by the circumferential surface (13) of the pump housing (2) and at least one counter-holder (15).

Description

Pump for conveying a liquid, in particular an exhaust gas purification additive

The invention relates to a pump for conveying a liquid, which is particularly suitable for conveying an exhaust gas purification additive (such as urea-water solution) into an exhaust gas treatment device for cleaning the exhaust gases of an internal combustion engine.

Exhaust gas treatment devices in which a liquid additive is used for exhaust gas purification are widely used, for example, in the motor vehicle sector, with nitrogen oxide compounds in particular also being to be removed from the exhaust gas. In such exhaust gas treatment devices, the so-called SCR process is performed (SCR = Selective Catalytic Reduction). In the SCR process, nitrogen oxide compounds in the exhaust gas are reduced with a reducing agent (usually ammonia). In many cases, ammonia is not stored directly in the motor vehicle, but rather is converted into ammonia in the form of a liquid (exhaust gas additive) which is external to the exhaust gas (in a dedicated external reactor) and / or internal to the exhaust gas (in the exhaust gas treatment device) Preferred urea-water solution is used A urea-water solution with a urea content of 32.5% is available under the trade name AdBlue®.

The liquid additive is usually stored in the motor vehicle in a tank and fed to the exhaust gas treatment device by means of a delivery module. A delivery module comprises in particular a pump. Furthermore, the following components can be assigned to the delivery module: filter, sensor, valve and / or dosing unit.

A problem with a delivery module for liquid additive is that these (for example the urea-water solution described above) freeze at low temperatures. A 32.5% urea-water solution freezes at -11 ° C. Such low temperatures can be used in the motor vehicle sector in particular. especially during long periods of standstill occur in winter. When the additive freezes, an increase in volume occurs, which can damage or even destroy the lines, channels and / or components of the conveyor module. Here, in particular, the pump is in focus. Destruction of the pump can be avoided, for example, by emptying the delivery module during deactivation so that no liquid additive remains in the delivery module during a standstill phase. Another approach is to design the components so flexibly that no damage can occur due to the volume expansion of the liquid additive during freezing.

In particular, inside the pump, it is technically difficult to provide measures for freeze protection, because the pump must be in intensive contact with the liquid additive. In addition, a complete emptying of the pump is often problematic, because this is a resumption of promotion after a shutdown significantly more difficult. The pump for delivering liquid additive should also be inexpensive and have a high durability. This includes, in particular, a high level of reliability or a low probability of failure as well as a low level of aging, in which case a change in the operating behavior of the pump as a result of wear is meant in particular.

In addition, where appropriate, an exact delivery capacity on the pump is important. By this, or by the term "dosing accuracy", is meant here in particular that the amount of liquid actually conveyed by the pump is exactly predetermined by clearly determinable input variables, the term "input variables" in this case in particular the electrical activation of the drive Pump (voltage profile and / or current profile for driving the pump, frequency of current pulses to drive the pump, etc.) describes. In particular, it is important that the number and / or relevance of cross influences, which influence the dependence of the delivery quantity on the input quantities, is kept low. Such cross influences could be, for example, the temperature of the pump, the pressure in the pump, etc. If significant cross- flows are unavoidable, the effect of these cross-influences on the flow should be The metering accuracy of a pump can be described, for example, by a statistical deviation between an expected, desired flow rate and an actually conveyed flow rate. For example, a pump has a high dosing accuracy, if this deviation is on average less than 10 percent. For example, a dosing accuracy (for HWL flow rates in the SCR process) can be regarded as low if this deviation is on average greater than 20 percent. These percentages are only examples.

From the documents US 2,544,628, US 3,408,947, DE 285 39 16 AI and DE 381 52 52 AI a pump type is known, which is also referred to as orbital pump. On the one hand, this type of pump is relatively resistant to a volumetric expansion of a liquid during freezing, on the other hand, this type of pump can also be operated in the reverse direction, so that emptying a delivery module is technically easily possible. However, there is a need to adapt this type of pump to the requirements in the environment of the SCR method, in particular with regard to the metering accuracy and / or the aging behavior (eg as a result of considerable stress conditions in the pump membrane).

On this basis, it is an object of the present invention to present a particularly advantageous pump for delivering a liquid which at least partially solves the above problems and in particular for the promotion of liquid additives for exhaust gas purification (such as urea-water solution) is suitable.

This object is achieved with a pump according to the features of patent claim 1. Further advantageous embodiments of the pump are specified in the dependent claims. It should be noted that the features shown in the individual claims in arbitrary, technological meaningful way can be combined with each other and can be supplemented by explanatory facts from the description, with further embodiments of the pump are shown. The proposal is for a pump for conveying a liquid, which has at least one pump housing with at least one inlet and at least one outlet and has an inner peripheral surface and a geometrical axis. Within the pump housing, an eccentric is arranged, which is rotatable about a geometric axis relative to the pump housing. Further, an (annular) deformable element is disposed between the inner peripheral surface of the pump housing and the eccentric, wherein with the deformable element and the (cylindrical) inner peripheral surface of the pump housing, a conveying channel is formed from the at least one inlet to the at least one outlet. The deformable element is pressed by the eccentric sections against the pump housing so that at least one sliding seal of the delivery channel and at least one closed pump volume are formed in the delivery channel, which is for conveying the liquid by a rotational movement of the eccentric along the delivery channel from the inlet the outlet are displaceable. At least one (annular) receptacle is formed by the inner peripheral surface of the pump housing and at least one counter-holder, in which at least one (annular) edge region of the deformable element is accommodated.

A pump of this construction may also be referred to as an orbital pump.

The pump has a (central) geometric axis about which the eccentric can be rotated. For this purpose, preferably along the drive axis, a drive shaft which connects the eccentric with a (electrically operable) drive. The drive is preferably arranged along the axis above and / or below the pump housing. For spatial description of the pump and its components, a radial direction is assumed below, which is perpendicular to the axis of the pump and starting extends radially outward from the axis of the pump. Perpendicular to the axis and to the radial direction should be defined a circumferential direction. The delivery channel runs from the inlet and to the outlet of the pump at least in sections along this circumferential direction through the pump housing or along the inner circumferential surface of the pump housing. For further description of the pump, a center plane of the pump is also defined. This median plane is perpendicular to the axis. In the middle plane are the pump housing, the eccentric, the deformable element and the delivery channel. The pump housing of the pump is preferably constructed in the manner of a ring or a cylindrical chamber, wherein the eccentric is arranged inside. The pump housing can also be considered as the (outer) stator of the pump, wherein the eccentric is referred to as (inner) rotor. According to a further embodiment of the pump, it is possible that the pump housing forms an inner stator, which is surrounded by the eccentric. Then the eccentric forms an outer rotor. The inlet and the outlet are arranged on the pump housing and allow the inflow and outflow of the liquid in the pump housing or in the delivery channel. This is a kinematic reversal of the structure described above with a pump housing as the outer stator and an inner rotor as the eccentric. The pump housing is preferably made of plastic. In the pump housing stiffening structures can be integrated. In a preferred embodiment, an annular metallic insert is integrated in a pump housing made of plastic, which stiffens the pump housing.

As used herein, the term "eccentric" means, in particular, a circular structure that is eccentrically (eccentrically) disposed about the axis and that makes an eccentric motion by rotation about the axis, and an annular gap between the pump housing and the eccentric The delivery channel is located (within the gap) between the deformable element and the pump housing, and is formed by the pump housing and the deformable Limited element. The gap has at least one constriction, which shifts by a rotation of the eccentric along the pump housing or along the conveying path. At the constriction, the deformable element is pressed against the housing, so that there is formed the sliding seal. Also included here are so-called multi-value eccentric, which form multiple bottlenecks between the pump housing and the eccentric. Such eccentrics can be designed, for example, as a roller eccentric, which press a plurality of rollers from the inside against the deformable element, wherein each of these rollers forms a bottleneck. The delivery channel has between the pump housing and the deformable element a liquid-flow channel cross section, which may be, for example (depending on the size of the pump) at the largest point between 1 mm ² [square millimeters] and 50 mm ² .

The delivery channel is annular or circumferentially formed around the geometric axis. The inlet s and the outlet s are preferably arranged in a conveying direction of the pump at an angular distance of more than 270 ° to one another (measured in the median plane). Contrary to the conveying direction of the inlet s and the outlet thus have an angular distance of less than 90 ° to each other. The eccentric is preferably designed in several parts. The eccentric preferably has an inner region which performs an eccentric rotational movement. In addition, an outer bearing ring may be provided, which surrounds the inner region. Between the inner region and the outer bearing ring is preferably at least one bearing. This bearing can be a ball bearing or a roller bearing. The inner eccentric of the eccentric executes a rotational movement about the geometric axis during operation. Due to the eccentric arrangement and possibly also due to the outer shape of the eccentric results in an eccentric movement of a surface of the eccentric. This eccentric movement is transmitted to the outer bearing ring. By means of a bearing between the inner area and a bearing ring, an eccentric rotational movement of the inner area can be converted into an eccentric wobble movement of the bearing ring, without the rotational movement component of the movement being compensated. tion of the inner area is transmitted. The fact that the movement of the bearing ring has no rotational movement component makes it possible to reduce shear stresses in the deformable element and internal friction forces of the pump. The deformable element is driven by the movement of the eccentric. At a contact surface of the eccentric and the deformable element preferably only compressive forces and substantially no frictional forces act. A corresponding division of the eccentric in an inner eccentric region and a bearing ring is also possible if the eccentric is an outer rotor which is arranged around an (inner) pump housing. It is also possible that is dispensed with the outer bearing ring and roll the rollers of the bearing directly on or on the deformable element.

The deformable element is preferably arranged between the eccentric and the pump housing in such a way that the eccentric presses the deformable element in regions against or against the pump housing such that the at least one displaceable seal is formed therewith. At the seal there is a (linear or surface) contact between the deformable element and the pump housing, which can not be flowed through by the liquid. In other words, the deformable element bears completely against the pump housing, so that the channel cross-section does not have a cross-sectional area in the region of this displaceable seal. The delivery channel is therefore interrupted in the region of the sliding seal. Thus, at least one closed pump volume is formed within the delivery channel. By a closed pump volume, it is meant that an at least one-sided sealed section of the delivery channel exists. By displacing the displaceable seal, the at least one closed pump volume is also displaced, so that the liquid which is located in the closed pump volume is conveyed. Preferably, in operation of the pump, a plurality of closed pump volumes are shifted from the inlet of the pump to the outlet of the pump to deliver the liquid. This forms a closed pump volume in the vicinity of the inlet (defined at least closed on one side) and then at the outlet. solved (defined at least unilaterally reopened). At the inlet, a closed pump volume is closed only on one side downstream of a sliding seal and connected upstream to the inlet, so that liquid can flow through the inlet into the closed pump volume. At the outlet, however, the closed pump volume is (only) closed on one side but upstream by a seal and connected downstream with the outlet, so that the liquid can flow out of the closed pump volume through the outlet. In between there exists (on the path of the closed pump volume from the inlet to the outlet) a phase in which the closed pump volume upstream and downstream is closed by the at least one sliding seal.

The deformable element may also be referred to as a deformable membrane. The term "membrane" does not necessarily state whether the deformable element has an areal extent. The term "membrane" is to be understood as an indication that the deformable element is a flexible structure can be deformed to promote liquid. As the material for the deformable element or the deformable membrane is preferably an elastomeric material (for example, rubber or latex) is used. To increase the durability and / or to produce and maintain flexibility, the material of the deformable element may contain additives. Preferably, the deformable element in all directions (in the axial direction along or parallel to the geometric axis, in the radial direction and in the circumferential direction) is flexible. However, it is also possible that the deformable element has a partially directed flexibility. For example, it may have a higher flexibility in the radial direction than in the circumferential direction and in the axial direction. Deformation of the deformable element in one direction typically also causes deformation in other directions. The deformable element expands, for example, in the axial direction and / or in the circumferential direction when it is compressed in the radial direction. A stationary seal is also preferably provided on the pump, which prevents unwanted backflow of the liquid from the outlet s to the inlet (counter to the conveying direction). The stationary seal may be provided stationary with the pump housing and positioned between the outlet and the inlet. The deformable element may be clamped or glued to the pump housing in the region of the stationary seal, for example, in order to permanently ensure a fluid-tight seal between the pump housing and the deformable element. The stationary seal is fluid-tight regardless of the position of the eccentric.

With the pump, a delivery of liquid in the conveying direction from the inlet to the outlet is preferably possible. By reversing the direction of rotation of the eccentric, a reversal of the conveying direction (instead of from the inlet to the outlet, vice versa from the outlet back to the inlet) is also possible.

For the solution of the problems outlined above, the at least one receptacle formed with the at least one counter-holder is of particular importance. Preferably, there are two counter-holders and two holders, which are arranged on both sides of the deformable element. In the following, the counter-holder and the elements of the pump described in connection with the counter-holder are often simply described, wherein it is then usually indicated that "at least" one counterholder or "at least" one further element (sealing contact, thickening, receiving, Stop surface, edge area, etc.) is present. By this formulation method, a pump should also be included, in which the described elements are formed only on one side of a median plane of the pump, wherein on the other side of the median plane another (deviating) structure is realized. However, it is preferred that the pump is constructed symmetrically to the center plane, so that all present on one side of the pump elements (counter-holder, Abdichtkontakt, thickening, recording, abutment surface, edge area, etc.) on the other side of the median plane (mirror image) another sometimes exists. The elements described (counter-holder, Abdichtkontakt, thickening, recording, abutment surface, edge area, etc.) are also preferably all annular. By this is meant that the elements (at least in sections) are formed rotationally symmetrical to the geometric axis of the pump. In particular, in the field of stationary sealing, however, said elements regularly deviate from the rotationally symmetrical shape. The said elements are interrupted there, for example. The mentioned elements are referred to here as "annular" despite deviations from the rotationally symmetrical shape. Therefore, the term "annular" here in particular also "at least partially ring-shaped", "predominantly annular" and or "partially annular" meant.

The deformable element preferably has two (annular) edge regions on both sides, which are positioned in two receptacles (preferably likewise annular) arranged correspondingly (in each case on both sides of the median plane). An edge region of the deformable element describes, in particular, a section of the deformable element which is particularly far outward in the axial direction parallel to the geometrical axis or a section of the deformable element which is particularly far away from the median plane. The counter-holder is preferably designed as an annular component which engages (only in sections) in the pump housing or the pump housing (only partially) surrounds, so that between the counter-holder and the pump housing the described (annular) receptacle is formed. In particular, the at least one counter-holder causes a radial clamping of the deformable element between the inner peripheral surface of the pump housing and the at least one counter-holder. The at least one edge region of the deformable element is clamped in the (annular) receptacle, so that a high sealing of a Abdichtkontakts between the pump housing and the deformable element and in particular no (lateral) leakage of liquid at the Abdichtkontakt from the delivery channel is possible. The sealing contact preferably runs along the entire conveying channel in the pump. Preferably, there are two (annular) Abdichtkontakte that the conveying channel both side axially (in the axial direction) limit. Preferably, the at least one counter-holder has an L-shaped cross-sectional area and engages in sections in the housing of the pump. The at least one counter-holder does not have to be connected to the pump housing. The at least one counter-holder can be movable relative to the pump housing. It is important that between the at least one counter-holder and the pump housing at least one (annular) receptacle is formed, in which the (annular) edge region of the deformable element is accommodated. The counter-holder may be part of a housing flange of the pump housing. The counter-holder may also be a non-connected to the pump housing, with respect to the pump housing movable member.

It is particularly preferred if the cylindrical inner circumferential surface of the pump housing continues along the geometric axis on both sides of the conveying path. This means in particular that the cylindrical inner circumferential surface (in the axial direction) is extended beyond the annular Abdichtkontakte addition. For example, the cylindrical inner peripheral surface (in the axial direction) extends on both sides between 1 mm [mm] and 10 mm beyond a channel cross section of the delivery channel. This makes it possible to ensure that the (annular) Abdichtkontakte the inner peripheral surface can not leave even with an axial displacement, but always lie completely in or on the inner peripheral surface. Furthermore, the pump is advantageous if at least one channel cross-section of the delivery channel is delimited by the cylindrical inner circumferential surface, a concave channel surface of the deformable element and two sealing contacts between the inner circumferential surface and the deformable element. For the solution of the problems described above, the special limitation of the delivery channel through the inner peripheral surface of the pump housing and the deformable element plays an important role. The delivery channel is struck pump limited by a cylindrical inner peripheral surface of the pump housing and a concave channel surface of the deformable element. The cylindrical inner peripheral surface is in particular a surface which has a plane cylindrical shape and is neither concave nor convex in the axial direction. Only the concave channel surface of the deformable element makes it possible for the delivery channel to have a flow-through cross section. The term "concave" here does not necessarily mean that a (uniform) curvature of the channel surface must exist. Rather, the term "concave" also expresses that the channel surface recedes between two Abdichtkontakten in the axial direction, so that the durchströmbare cross section is formed by the concave channel surface. Preferably, the two (annular) Abdichtkontakte extend between the deformable element and the inner peripheral surface along the conveying channel and along the circumferential direction. In other words, in a sectional plane through the delivery channel spanned by the geometric axis and any radial direction, the channel cross-section is a concave arc segment of the deformable element, a line formed by the inner peripheral surface of the pump housing, and two point contact points between the arc segment (the deformable element) and the line (of the pump housing) limited. Regardless of the operating conditions of the pump, the inner peripheral surface of the pump housing is a clear boundary of the delivery channel (in the radial direction). The at least one annular sealing contact thus always lies on the peripheral surface. A seal of the annular Abdichtkontakte takes place in the radial direction. By this is meant that a radial clamping force acts on the sealing contacts. This leads to a particularly favorable stress distribution within the deformable element. When conveying occur in the deformable element on the displaceable seal substantially acting in the radial direction of compressive forces. Due to the radial clamping force of the annular sealing contacts, all forces acting in the deformable element are substantially the same. When the described sectional plane (spanned by the geometric axis and the radial direction) in the region of the displaceable seal is viewed through the deformable element and the pump housing, the deformable element lies there linearly against the inner circumferential surface, so that the channel cross-section is completely closed ,

By the design of an orbital pump described here, undesired multiaxial stress states in the deformable element can be effectively avoided. This considerably reduces the aging of the deformable element. The design of an orbital pump described here has a significantly improved durability. In addition, a good metering accuracy of the pump over a long period of operation of the pump can be ensured.

Furthermore, it is advantageous if at least one stop surface is located laterally of the deformable element in the at least one (annular) receptacle, and wherein the at least one (annular) edge region bears against the at least one stop surface.

The at least one stop surface is preferably also annular. Preferably, the at least one stop surface is arranged in a plane orthogonal to the geometric axis of the pump. Preferably (in the axial direction along the geometric axis) on both sides of the deformable element stop surfaces are provided which limit the two (annular) recordings in each case in the axial direction. As the pressure in the delivery channel increases, the marginal area is forced (even more) against the abutment surface of the annular receiver. In this case, the deformable element expands in the radial direction, because more material of the deformable element is pressed into the annular receptacle. As a result, a contact pressure between the pump housing and the deformable element is increased at the Abdichtkontakten. The sealing effect for (lateral) sealing of the delivery channel thus increases at elevated pressure in the delivery channel. Particularly preferably, both edge regions of the deformable element are arranged in corresponding annular receptacles on the side of the deformable element, so that, starting from the mid-plane of the pump, a symmetrical adaptation of the deformable element to the pressure in the conveying channel occurs, the edge regions being affected by the increased pressure (FIG. even stronger) are pressed against the stop surfaces arranged on both sides.

The pump is also particularly advantageous if the at least one (ring-shaped) receptacle tapers outwardly in the radial direction, starting from a central plane of the pump that is perpendicular to the geometric axis. This means, in particular, that an annular gap which forms the receptacle becomes narrower towards the outside (steadily). In this way, it can be achieved that the edge region of the deformable element is compressed more strongly by the pump housing or the anvil, the more it is pressed against the stop surface. This means that the force of the radial clamping then increases accordingly. Consequently, the contact pressure on the at least one sealing contact increases, so that the sealing effect on the at least one sealing contact is increased.

Furthermore, the pump is advantageous if the at least one sealing contact of at least one (circumferential) thickening is formed in the edge region of the deformable element. Preferably, a concave channel surface of the deformable element is at least partially formed by the circumferential thickening in the edge region. The concave channel surface has a central area which is surrounded (on both sides) by the circumferential thickening and which in a preferred embodiment is flat. By such a thickening, the sealing effect on the Abdichtkontakt occurs as in a conventional O-ring seal. An O-ring seal is a particularly effective sealing concept whose sealing effect is known. In particular, it is possible to calculate the pressure-dependent sealing effect of the Abdichtkontakts depending on the pressure in the conveyor channel and the thickening and recording to be dimensioned accordingly. The characteristic "concave" of the channel surface can additionally be supported by a concave shape of the central region of the channel surface. Furthermore, it is advantageous if the channel surface of the deformable element is interrupted by a recess which is arranged between the outlet s and the inlet and in which a holding portion of the pump housing engages. The recess represents in particular an interruption of the annular shape of the channel surface of the deformable element. Preferably, the recess does not extend over the entire deformable element, so that the deformable element forms a closed ring despite the recess. The recess only interrupts an (outer) region of the deformable element in which the channel surface of the deformable element is located. The holding portion is preferably a portion of the pump housing, which is fixedly connected to the pump housing or an additional component which can be inserted into the pump housing. In particular, the retaining portion also prevents rotation of the deformable member relative to the pump housing because the retaining portion provides a positive constraint to such rotation. In addition, the combination of the recess and the retaining portion may form the stationary seal which prevents backflow from the outlet back to the inlet.

Furthermore, it is preferred if the recess on the deformable element has an undercut on each side and the channel surface of the deformable element in the form of an extension extends in sections over the undercut, wherein the extensions are clamped to the holding section on the pump housing. This is a particularly advantageous way to form a stationary seal. The holding portion is preferably T-shaped at least in sections, so that it engages in the undercuts, the extensions engages around and presses against the inner peripheral surface of the pump housing. In a further preferred embodiment, the force with which the holding section clamps the extensions can be adjusted individually. be set to achieve a suitable sealing effect on the stationary seal. This can be achieved with a set screw which positions the holding section relative to the housing to define the sealing force acting on the extensions (during assembly of the pump).

It is also advantageous if at least one Abdichtkontakt the Kanaloberflä- surface of the deformable element and the inner peripheral surface of the pump housing exists, which completely surrounds the channel surface and intersects in the region of the recess perpendicular to the geometric axis center plane of the pump. Preferably, the sealing contact intersects the center plane twice, namely in each case in the edge region on the extensions in the region of the recess. The channel surface forms an annular surface which is not closed (at the recess) and has a peripheral edge region which completely surrounds the channel surface of the deformable element. The sealing contact is formed in the entire edge region of the channel surface. By means of such a design of the deformable element and of the delivery channel, a particularly secure and uniform sealing of the delivery channel can take place, which in particular leads to a low distortion of the deformable element and helps to avoid multiaxial stress states in the deformable element.

Furthermore, a motor vehicle is proposed, comprising an internal combustion engine, an exhaust gas treatment device for cleaning the exhaust gases of the internal combustion engine, and a pump described, wherein the pump is adapted to a liquid additive (in particular urea-water solution) for exhaust gas purification (in particular after the SCR). Method) to promote from a tank to an injector, with which the liquid additive of the exhaust gas treatment s device can be supplied.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the figures and in particular the sizes shown in the figures are only schematically. The figures serve to illustrate individual features of the described Pump. In the different embodiments illustrated variants can be combined with each other in any way. In particular, it is not necessary that all features shown in a figure are each considered as a unit. Show it:

1 is an isometric view of a pump,

2 shows a section through the pump of Fig. 1,

3 shows a deformable element of a pump,

4 shows a section through the deformable element of Fig. 3,

5 shows a sectional section through the pump of FIG. 2,

6 shows a section corresponding to FIG. 5 through a pump of the prior art, FIG.

FIG. 7 shows a further illustration of the section from FIG. 5, and FIG

8 shows a motor vehicle, comprising a pump for carrying out the SCR method.

FIG. 1 shows a pump 1 which has a pump housing 2 with an inlet 3 and an outlet 4. In the pump housing 2, an eccentric (not shown here) can be positioned, which can be rotated to convey liquid from the inlet 3 to the outlet 4. To drive the eccentric a (electric) drive 49 is provided along a geometric axis 53 of the pump 1 above the pump housing 2, which is connected via a drive shaft 48 to the eccentric. The geometric axis 53 corresponds to a drive shaft 6 of the pump. For further description of the pump 1, in addition to the geometric axis 53, a cylindrical coordinate System having a geometric axis 53, a perpendicular to the geometric axis 53 standing radial direction 28 and a perpendicular to the geometric axis 53 and the radial direction 28 standing, arranged tangentially to the geometric axis 53 circumferential direction 47 are illustrated. In addition, a median plane 18 may be designated, which divides the pump housing 2 and the components arranged in the pump housing 2 (in particular the eccentric, not shown, and a deformable element, not shown) in the middle. Preferably, the pump housing 2, the eccentric and the deformable element are each formed symmetrically to the center plane 18.

FIG. 2 shows a section through the pump according to FIG. 1 in the defined center plane. To illustrate this, the circumferential direction 47 and the radial direction 28 are indicated in the figure. Evident is the pump housing 2 with the inlet 3 and the outlet 4, which are arranged at an angle 50 to the pump housing 2. In the pump housing 2 is an eccentric 5, which can perform about a geometrical axis 53 an eccentric wobbling motion. The eccentric 5 is divided into an inner eccentric region 29, an outer bearing ring 30 and a bearing 31. When the inner eccentric portion 29 makes an eccentric rotation about the geometrical axis 53, the bearing 31 transmits it to the bearing ring 30, so that the bearing ring 30 performs an eccentric tumbling motion. Between the pump housing 2 and the eccentric exists a deformable element 7 and a delivery channel 8. The delivery channel 8 is formed between the pump housing 2 and the deformable element 7. Sectionally, the eccentric 5 presses the deformable element 7 against the pump housing 2 such that a displaceable seal 9 is formed, which interrupts the delivery channel 8 and subdivides the delivery channel 8 into closed pump volumes 10. By a rotation of the eccentric 5, the displaceable seal 9 can be displaced along a conveying direction 11 from the inlet 3 to the outlet 4. The deformable element 7 according to FIG. 2 has a stationary seal 25 between the inlet 3 and the outlet 4, which prevents a backflow of liquid from the outlet 4 to the inlet 3. The stationary seal 25 is formed with a recess 21 which has undercuts 22, which are respectively spanned by extensions 23 of the deformable element. The recess 21 is here designed T-shaped. In the recess 21 engages a holding portion 24 of the pump housing 2 a. This holding portion 24 may be an integral part of the pump housing 2 or a separate from the pump housing 2, additionally inserted into the pump housing 2, component. By means of the recess 21 and the holding section 24, the deformable element 7 is fixed in a rotationally fixed manner in the pump housing 2.

Fig. 3 shows an isometric view of the deformable element 7 of the pump. For spatial orientation, the coordinate system of the geometric axis, the circumferential direction 47 and the radial direction 28 is shown in the figure. The deformable element 7 has an (outer) concave channel surface 46 which, together with the inner peripheral surface of the pump housing, not shown here, delimits the delivery channel (also not shown). The term "concave" here means, in particular, that the concave channel surface 46 is concave in the direction of the geometric axis 53. The concave shape of the channel surface 46 is illustrated in Fig. 3 by a dashed marking line 52. The concave channel surface 46 of FIG deformable element 7 has in a circumferential edge region 20, a thickening 19, which has a Abdichtkontakt 12, in which the deformable element 7 on the not shown here inner circumferential surface of the (also not shown) pump housing is present. the concave channel surface 46 is caused by the bilateral thickening 19. The bilateral thickening 19 surrounds a central region 54 on the deformable element 7, the central region 54 being preferably flat In addition, the central area 54 itself au ch still have a concave shape. To recognize is also the recess 21 on the concave channel surface 46 of the deformable element 7. The recess 21 is bounded on both sides by an undercut 22 and extending over the undercuts 22 extensions 23. In the recess 21 engages a holding portion 24 of the pump housing, not shown here. With the recess 21, the above-described stationary seal 25 is formed.

Fig. 4 shows the deformable element 7 shown in Fig. 3 in a sectional view. For orientation, the geometric axis 53 and the radial direction 28 are shown in FIG. 4. Evident is also the concave channel surface 46 of the deformable element 7, which is illustrated by the marking line 52. The concave shape of the concave channel surface 46 is formed by the thickening 19 in the edge region 20 and the central region 54 of the channel surface 46. The thickening 19 in the edge region also forms the Abdichtkontakte 12. On the right side, the deformable element 7 is shown in the region of the recess 21, so that the undercut 22 and an extension 23 can be seen. 4, it can also be seen that the deformable element 7 has an abutment region 43 and a support region 27 which are connected to each other by a waist 26, wherein the abutment region 43, the channel surface 46 for abutment with the pump housing 2 and the formation of the delivery channel 8 is formed together with the pump housing 2. On the support portion 27, a clamping groove 33 is provided, with which the deformable element 7 on a terminal block (not shown here eccentric) can be clamped.

FIG. 5 shows the sectional section BB marked in FIG. 2 through the pump. For orientation, the center plane 18 and the radial direction 28, and the geometric axis 53 are noted here. Evident are the pump housing 2, the eccentric 5 and the deformable element 7 between the eccentric 5 and the pump housing 2. In addition, the inner circumferential surface 13 of the pump housing 2 and the concave channel surface 46 of the deformable element 7, as well as the two linear Abdichtkontakte 12 between the deformable element 7 and the pump housing 2, which together define the channel cross section 45. The deformable element 7 has a contact region 43, which forms the concave channel surface 46, and a support region 27 against which the eccentric 5 bears. Between the contact region 43 and the support region 27 there is preferably a waist 26, which is tapered relative to the contact region 43 and / or with respect to the support region 27. In the support region 27, the deformable element 7 has a clamping groove 33 into which a clamping strip 44 of the eccentric 5 engages. The concave channel surface 46 is formed by a (flat) central region 54 and adjoining edge regions 20 on both sides, wherein in the edge regions 20 each of thickenings 19 are formed. Between the edge regions 20 and the central region 54 can each attachment areas 51 exist in which the deformable element 7 is particularly well deformable. The extent of the connection regions 51 is illustrated here by dashed lines by way of example. This improves the mobility of the edge regions 20 or of the sealing contacts 12 and of the thickenings 19 with respect to the central region of the deformable element 7.

5, two counter-holders 15 are also shown, which are formed by housing flanges 55 which are used as annular components on both sides in the pump housing 2 and thus each form an annular receptacle 14 in which the edge regions 20 of the deformable element 7 are located. The counter-holder 15 and the pump housing 2 surround the deformable element 7 (only) in sections. In the receptacle 14 is located laterally of the deformable element 7 in each case a stop surface 16 on which the deformable element 7 is located. When the pressure in the conveying channel 8 increases, the edge portions 20 are pressed more strongly against the abutment surfaces 16. The receptacles 14 preferably have outwardly (in the direction of the geometric axis 53 away from the median plane 18) a chamfer 17, through which the receptacles 14 taper towards the abutment surfaces 16 to the outside. In this way, it can be achieved that a pressing force on the sealing contact 12 increases, the more firmly the edge region 20 is pressed outward against the abutment surface 16 by the pressure in the conveying channel 8. In Fig. 5 is also shown that in the pump housing 2, an insert 32 is integrated, which stiffened the pump housing 2. The pump housing 2 is preferably made of plastic and the insert 32 is preferably a metallic ring, which stiffens the pump housing 2 such that it is not deformed by a movement of the eccentric 5.

FIG. 6 shows a corresponding cross section in a pump according to the prior art (for example according to the documents US Pat. No. 2,544,628, US Pat. No. 3,408,947, DE 285 39. FIG 16 AI and DE 381 52 52 AI) and Fig. 7 illustrates a corresponding cross section through a pump of the type described here. For orientation, the center plane 18, the radial direction 28 and the geometric axis 53 are applied here in each case (as in FIG. 5). Further to be seen are the pump housing 2, the eccentric 5 and the deformable element 7 and the counter-holder 15, which are formed by housing flanges 55, with which the deformable element 7 is clamped to the pump housing 2. According to the embodiment of the prior art in Fig. 6, the deformable element 7 extends in sections around the pump housing 2 around and is clamped with an axial clamping 34 between the counter-holders 15 and the pump housing 2. According to FIG. 7, a radial clamping 35 of the deformable element 7 exists between the pump housing 2, the counter-holder 15 and the receptacles 14, as has already been described in connection with FIG. 5 by the corresponding arrangement of the annular edge regions 20 of the deformable element 7 ,

FIG. 8 shows a motor vehicle 36, comprising an internal combustion engine 37 and an exhaust gas treatment device 38 for cleaning the exhaust gases of the internal combustion engine 37. In the exhaust gas treatment device 38, an SCR catalytic converter 39 is arranged, with which the selective catalytic reduction process for cleaning the exhaust gas Exhaust gases of the internal combustion engine 37 can be performed. The exhaust treatment device 38 may with a Injector 41 a liquid additive for exhaust gas purification are supplied. The injector 41 is supplied via a line 42 with liquid additive from a tank 40. On line 42, a described pump 1 is arranged, which performs the promotion and possibly also the dosage of the liquid additive.

LIST OF REFERENCE NUMBERS

1 pump

2 pump housings

3 inlet s

4 outlet

5 eccentrics

6 drive axle

7 deformable element

8 conveying channel

9 sliding seal

10 pump volumes

11 conveying direction

12 sealing contact

13 inner peripheral surface

14 recording

15 counterholds

16 abutment surface

17 bevel

18 median plane

19 Thickening

20 edge area

21 recess

22 undercut

23 extension

24 holding section

25 Stationary sealing

26 waist

27 support area

28 radial direction

29 eccentric area

30 bearing ring 31 bearings

32 deposit

33 clamping groove

34 axial clamping

35 radial clamping

36 motor vehicles

37 internal combustion engine

38 exhaust treatment device

39 SCR catalyst

40 tank

41 injector

42 line

43 investment area

44 terminal block

45 channel cross section

46 concave channel surface

47 circumferential direction

48 drive shaft

49 drive

50 angles

51 connection area

52 marking line

53 geometric axis

54 central area

55 Housing flange

Claims

Patent claims

Pump (1) for conveying a liquid, comprising at least one pump housing (2) with at least one inlet (3) and at least one outlet (4) and with an inner circumferential surface (13) and a geometric axis (53), wherein within the pump housing ( 2) an eccentric (5) is arranged which can be rotated about the geometric axis (53) relative to the pump housing (2), with a deformable element (13) between the inner peripheral surface (13) of the pump housing (2) and the eccentric (5). 7) is arranged and wherein a delivery channel (8) from the at least one inlet (3) to the at least one outlet (4) is formed with the deformable element (7) and the inner peripheral surface (13) of the pump housing (2) and further the deformable element (7) from the eccentric (5) in sections against the pump housing

(2) is pressed, so that at least one displaceable seal (9) of the delivery channel (8) and at least one closed pump volume (10) are formed in the delivery channel (8), which are used to deliver the liquid by a rotary movement of the eccentric (5). along the delivery channel (8) from the inlet

(3) to the outlet

(4) are displaceable, with at least one receptacle (14) being formed by the inner peripheral surface (13) of the pump housing (2) and at least one counterholder (15), in which at least one edge region (20) of the deformable element (7) is accommodated .

Pump (1) according to claim 1, wherein the inner peripheral surface (13) continues on both sides along the geometric axis to the side of the delivery path.

Pump (1) according to claim 1 or 2, wherein at least one channel cross section (45) of the delivery channel (8) through the inner peripheral surface (13), a concave channel surface (46) of the deformable element (7) and two Sealing contacts (12) between the inner peripheral surface (13) and the deformable element (7) is limited.

Pump (1) according to one of the preceding claims, wherein At least one stop surface (16) is located on the side of the deformable element (7) in the at least one receptacle (14) and the at least one edge region (20) rests on the at least one stop surface (16).

5. Pump (1) according to claim 3 or 4, wherein the at least one receptacle (14) tapers outwards in the radial direction (28) starting from a central plane (18) of the pump (1) which is perpendicular to the axis (6). .

6. Pump (1) according to one of the preceding claims, wherein the at least one sealing contact (12) is formed by at least one thickening (19) in the at least one edge region (20) of the deformable element (7).

7. Pump (1) according to one of the preceding claims, wherein the channel surface (46) of the deformable element (7) is interrupted by a recess (21) which is arranged between the outlet (4) and the inlet (3) and in which engages a holding section (24) of the pump housing (2).

8. Pump (1) according to claim 7, wherein the recess (21) on the deformable element (7) has an undercut (22) on both sides and the channel surface (46) of the deformable element (7) is in the form of an extension ( 23) extends in sections over the undercut (22), the extensions (23) being clamped to the holding section (24) on the pump housing (2). Pump (1) according to one of claims 7 or 8, wherein at least one sealing contact (12) of the channel surface (46) of the deformable element (7) and the inner peripheral surface (13) of the pump housing (2) exists, which completely covers the channel surface (46). encloses and in the area of the recess (21) intersects a central plane (18) of the pump (1) which is perpendicular to the drive axis (6).

Motor vehicle (36), comprising an internal combustion engine (37), an exhaust gas treatment device (38) for cleaning the exhaust gases of the internal combustion engine (37), and a pump (1) according to one of the preceding claims, wherein the pump (1) is designed to do so to convey liquid additive for exhaust gas purification from a tank (40) to an injector (41), with which the liquid additive can be supplied to the exhaust gas treatment device (38).