Pump for conveying a liquid

Abstract

Pump for conveying liquid, having at least one pump housing with at least one inlet and at least one outlet, and including an inner circumferential surface and a geometric axis, where an eccentric is arranged within the pump housing and is moveable eccentrically relative to the pump housing around the geometric axis. A deformable element is arranged in a pump gap between the inner circumferential surface of the pump housing and an outer surface of the eccentric. The deformable element is pressed against the pump housing by the outer surface of the eccentric along at least one section of a conveying channel such that at least one displaceable seal of the conveying channel and at least one closed pump volume are formed in the conveying channel which are displaceable by an eccentric movement of the eccentric for conveying the fluid along the conveying channel from the inlet to the outlet.

Claims

1. A pump for delivering a liquid, comprising: at least one pump housing having at least one inlet and at least one outlet; an inner circumferential face, the inner circumferential face being part of the at least one pump housing; a geometric axis extending through the at least one pump housing; an eccentric having an outer face, the eccentric being arranged within the pump housing such that the eccentric is movable in eccentric fashion relative to the pump housing about the geometric axis; a structured surface formed as part of the outer face, the structured surface further comprising: a pattern of depressions integrally formed on the outer face, wherein the depressions are delimited in encircling fashion; a deformable element arranged in a pump gap between the inner circumferential face of the pump housing and the outer face of the eccentric; and a delivery duct in fluid communication with the at least one inlet and the at least one outlet, the delivery duct being located between the deformable element and the inner circumferential face of the pump housing; wherein the deformable element is pressed against the pump housing along at least one section of the delivery duct by the outer face of the eccentric such that at least one displaceable seal of the delivery duct and at least one closed pump volume are formed in the delivery duct, the at least one displaceable seal and the at least one closed pump volume being displaceable along the delivery duct from the inlet to the outlet by eccentric movement of the eccentric for the delivery of the liquid.

2. The pump of claim 1, the deformable element further comprising: a pressure distribution formed by the structured surface in the area of the displaceable seal, the pressure distribution having at least one local pressure maximum and at least one local pressure minimum located along the delivery duct.

3. The pump of claim 2, wherein the structured surface is shaped such that the pressure in the deformable element at the local pressure minimum is higher than a predetermined maximum operating pressure of the pump.

4. The pump of claim 1, further comprising: an outer bearing ring, the outer face having the structured surface being formed on the outer bearing ring; an inner eccentric region; and a bearing located between the outer bearing ring and the inner eccentric region; wherein eccentric rotational movement of the inner eccentric region is converted into eccentric circulating movement of the outer bearing ring.

5. The pump of claim 4, wherein the outer bearing ring of the eccentric is rotationally fixed relative to the pump housing.

6. The pump of claim 1, wherein the structured surface of the outer face of the eccentric further comprises a smooth angle segment about the geometric axis, wherein the smooth angle segment covers at least the inlet or the outlet.

7. The pump of claim 1, further comprising: an internal combustion engine; and an exhaust-gas treatment device for the purification of the exhaust gases of the internal combustion engine; wherein the pump is designed to deliver a liquid additive for exhaust-gas purification from a tank to an injector, by means of which the liquid additive is supplied to the exhaust-gas treatment device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

(2) FIG. 1: shows a three-dimensional view of a described pump,

(3) FIG. 2: shows a section through a described pump along a central plane,

(4) FIG. 3: shows an eccentric for a described pump,

(5) FIG. 4: is a functional illustration of a displaceable seal of the described pump,

(6) FIG. 5: shows a pressure distribution in a deformable element in the region of a displaceable seal of the described pump,

(7) FIG. 6: shows a first design variant of an outer face of the eccentric in a described pump,

(8) FIG. 7: shows a second design variant of an outer face of the eccentric in a described pump,

(9) FIG. 8: shows a third design variant of an outer face of the eccentric in a described pump,

(10) FIG. 9: shows a fourth design variant of an outer face of the eccentric in a described pump,

(11) FIG. 10: is a functional illustration of a static seal in a further design variant of a described pump,

(12) FIG. 11: is a functional illustration of a static seal in a yet further design variant of a described pump,

(13) FIG. 12: shows a section through a described pump,

(14) FIG. 13: shows a section through a particular design variant of the described pump along the central plane, and

(15) FIG. 14: shows a motor vehicle having a described pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(16) The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

(17) FIG. 1 shows a three-dimensional view of the pump 1. For the description of the pump 1 in spatial terms, a geometric axis 23 is defined. For the description of the spatial arrangement of the pump, a radial direction 28 and a circumferential direction 27 are also illustrated. The pump 1 has a pump housing 2 with an inlet 3 and an outlet 4. The drive 24 of the pump 1 is arranged above the pump housing 2 along the geometric axis 23, which drive 24 is connected via a drive shaft 26 to the eccentric (not illustrated here) in the pump housing 2. Also defined is a central plane 14 in which the pump housing 2 and the eccentric (not illustrated here) are situated and which preferably forms a plane of symmetry at least for the pump housing 2 and the eccentric.

(18) FIG. 2 shows a section through the pump illustrated in FIG. 1 along the central plane 14 illustrated in FIG. 1. For orientation, the circumferential direction 27 and the radial direction 28 are illustrated in FIG. 2. The figure shows the pump housing 2 with the inlet 3 and the outlet 4. Situated in the pump housing 2 is the eccentric 5, which has an inner eccentric region 29, an outer bearing ring 30 and a bearing 31. Between the eccentric 5 and the pump housing 2 there is a pump gap 11, the width of which can be varied (in each case locally) by the eccentric movement of the eccentric 5. The pump gap 11 is formed in particular between an inner circumferential face 13 of the pump housing 2 and an outer face 6 of the eccentric 5.

(19) An (annular) deformable element 7 is arranged in the pump gap 11. The delivery duct 8 is formed in the pump gap 11, between the deformable element 7 and the pump housing 2. Because of the eccentricity of the eccentric 5, a displaceable seal 9 is formed at which the deformable element bears directly against the pump housing 2 and the delivery duct 8 is thus blocked. The displaceable seal 9 divides the delivery duct 8 into displaceable pump volumes 10. The displaceable seal 9 is in particular formed by virtue of the deformable element 7 bearing against the inner circumferential face 13 of the pump housing 2. The pump 1 furthermore has a static seal 25 of the delivery duct 8. Here, the static seal 25 is formed by virtue of the deformable element 7 being clamped to the pump housing 2, by means of a pin 22, between the outlet 4 and the inlet 3. No liquid can pass through the static seal 25 between the pump housing 2 and the deformable element 7. The static seal 25 thus prevents a back flow of liquid along the delivery duct 8 from the outlet 4 to the inlet 3. The liquid is delivered through the delivery duct 8 in a delivery direction 43 as a result of an eccentric movement of the eccentric 5. The delivery direction 43 is reversed by means of a reversal of the direction of the eccentric movement. The outer face 6 of the eccentric 5 has a structured surface 15, such that the eccentric 5 bears against the deformable element 7, or presses against the deformable element 7, only in regions.

(20) FIG. 3 illustrates the eccentric 5 of the deformable element with the outer face 6 in a three-dimensional view. The outer face 6 has, as a structured surface 15, an undulation 19 with undulation peaks 32 and undulation troughs 33. For orientation, the geometric axis 23, the radial direction 28 and the circumferential direction 27 are also illustrated in FIG. 3.

(21) FIG. 4 is a functional illustration of a displaceable seal 9 of the pump described here. The illustration of FIG. 4 corresponds to a conversion of the actually curved delivery duct into a linear illustration.

(22) The illustration shows the pump housing 2, the eccentric 5 and the deformable element 5 arranged in between. For orientation, the radial direction 28 and the circumferential direction 27 are indicated by arrows. The eccentric 5 has, on its outer face 6, a structured surface 15 in the form of a profile with an undulation 19 with undulation peaks 32 and undulation troughs 33.

(23) FIG. 5 illustrates, in a diagram, a pressure distribution 16 such as arises in the deformable element at the displaceable seal 9 as per FIG. 4 owing to the structured surface of the eccentric. The vertical axis of the diagram is a pressure axis 44, on which the pressure is plotted. The horizontal axis of the diagram corresponds to the circumferential direction 27. The diagram shows a theoretical pressure distribution 45 that would arise in the deformable element in the region of the displaceable seal owing to the eccentricity of the eccentric if the eccentric did not have a structured surface. Owing to the structured surface, the actual pressure distribution 16 deviates from the theoretical pressure distribution 45. Pressure minima 18 exist in the deformable element in the region of undulation troughs of the structured surface which is formed as an undulation, whereas pressure maxima 17 exist in the region of the undulation peaks of the structured surface which is formed as an undulation. Also illustrated in the diagram in FIG. 5 is the operating pressure 12. It can be seen that the pressure minima 18 are higher than the operating pressure 12.

(24) FIGS. 6, 7, 8 and 9 each show outer faces 6 for eccentrics 5, wherein linear embodiments corresponding to FIG. 4 have been selected in each case for the illustrations. The outer face 6 of the eccentric 5 in FIGS. 6, 7, 8 and 9 has a structured surface 15 in each case.

(25) In FIG. 6, the structured surface 15 is formed as an undulation 19 with undulation peaks 32 and undulation troughs 33, wherein the undulation troughs 33 are each realized as channels with semicircular cross section.

(26) FIG. 7 shows a structured surface 15 as an undulation 19 with undulation peaks 32 and undulation troughs 33, wherein the undulation troughs 33 and the undulation peaks 32 are in each case of rectangular form.

(27) FIG. 8 shows a structured surface 15 which is designed as an undulation 19 and which likewise has undulation peaks 32 and undulation troughs 33, wherein, in FIG. 8, the undulation troughs 33 are in each case axially delimited. The undulation troughs 33 thus simultaneously also form depressions 40 in the outer face 6 of the eccentric 5.

(28) FIG. 9 shows a structured surface 15 which can also be referred to as a golf ball surface 42 and which comprises regularly arranged, preferably (hemi)spherical depressions 40 in the outer face 6 of the eccentric 5.

(29) FIGS. 10 and 11 explain further or alternative design variants of a pump which are very similar to the pump described here. The design features described here for the pump (in particular the design features claimed in the subclaims) can be transferred analogously to the alternative design variants of a pump explained in FIGS. 10 and 11. The alternative design variants described in FIGS. 10 and 11 can be used instead of a structured surface of the outer face 6 of the eccentric 5. The design variants specified in FIGS. 10 and 11 are in particular also intended to be described here independently of the claimed design variant of the pump, and may possibly be pursued within the context of divisional applications.

(30) FIGS. 10 and 11 each show the pump housing 2, the eccentric 5 and the deformable element 7 correspondingly to the illustration in FIG. 4. For orientation, the radial direction 28 and the circumferential direction 27 are marked. The figures show the pump gap 11 between the pump housing 2 and the eccentric 5, in which pump gap the deformable element 7 is arranged. At the displaceable seal 9, the deformable element 7 is pressed against the pump housing 2 by the eccentric 5.

(31) In FIG. 10, instead of a structured surface 15 on the outer face 6 of the eccentric, a structured surface 15 is formed on that side of the deformable element 7 which faces toward the outer face 6. Any of the variants illustrated in FIGS. 6, 7, 8 and 9 may be selected for said structured surface 15. By means of such a structured surface 15 on the deformable element 7, a pressure distribution in the deformable element 7 can be obtained which corresponds to that in FIG. 5.

(32) In FIG. 11, instead of a structured surface, inserts 46 are arranged in regions in the deformable element 7. Said material inserts 46 may be arranged in a regular pattern, which corresponds for example to a pattern from one of FIG. 6, 7, 8 or 9. By means of said inserts 46, it is likewise possible for a pressure distribution corresponding to FIG. 5 to be realized in the deformable element 7.

(33) FIG. 12 shows a section through a described pump of arbitrary type along the section direction B-B from FIG. 2. The radial direction 28 and the geometric axis 23 of the pump are shown.

(34) The illustration shows in particular the pump housing 2, the eccentric 5 and the deformable element 7. FIG. 12 shows the annular axial seals 20 that are formed, on both sides of the delivery duct 8, between the pump housing 2 and the deformable element 7 in order to seal off the delivery duct 8 (axially) on both sides. Said annular axial seals 20 may for example be realized by clamping and/or adhesive bonding of the deformable element 7 to the pump housing 2.

(35) FIG. 13 shows a section through a pump 1, which corresponds to the section through a pump 1 illustrated in FIG. 2. The outer face 6 of the eccentric 5 of the pump 1 from FIG. 13 additionally has an angle segment 41 which does not have a structured surface 15. Said angle segment 41 is arranged so as to face the inlet 3 and the outlet 4, such that the angle segment 41 covers the inlet 3 and the outlet 4.

(36) FIG. 14 shows a motor vehicle 36 having an internal combustion engine 37 and having an exhaust-gas treatment device 38 for the purification of the exhaust gases of the internal combustion engine 37. In the exhaust-gas treatment device 38 there is arranged an SCR catalytic converter 39 by means of which exhaust gases of the internal combustion engine 37 can be purified by means of the process of selective catalytic reduction. On the exhaust-gas treatment device 38 there is arranged an injector 34 to which liquid for exhaust-gas purification can be supplied from a tank 21 by means of a described pump 1. For this purpose, the tank 21, the pump 1 and the injector 34 are connected to one another via a line 35.

(37) The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.