Method for operating a pump

Abstract

A pump includes a pump housing, an inlet, an outlet, a rotatable eccentric, a deformable element between housing and eccentric and a delivery channel from inlet to outlet formed by the deformable element and the housing. The deformable element is pressed against the housing in sections by the eccentric forming a movable seal of the channel and a closed volume in the channel being movable along the channel from inlet to outlet to pump the liquid by rotating the eccentric. A method for operating the pump includes a) setting a liquid quantity to be pumped, b) determining a temperature of the deformable element, c) determining a parameter considering the temperature from step b), the parameter representing a dependence between movement of the eccentric and pump capacity and d) pumping the liquid quantity set in step a) by adapting an operating mode of the pump considering the parameter from step c).

Claims

1. A method for operating a pump for conveying a liquid, the method comprising the following steps: providing at least one pump housing having at least one inlet and at least one outlet; placing an eccentric at the at least one pump housing, the eccentric being rotatable about an axis relative to the at least one pump housing; placing a deformable element between the at least one pump housing and the eccentric; the deformable element and the at least one pump housing forming a delivery channel from the at least one inlet to the at least one outlet; providing at least one temperature sensor for determining a temperature of said deformable element; providing opposing counter elements mounted on the at least one pump housing and abutting the deformable element, the counter elements sealing the deformable element on the at least one pump housing, one of the counter elements having a channel formed therein for the temperature sensor, the channel opening against the deformable element; the eccentric pressing the deformable element in sections against the at least one pump housing to form at least one displaceable seal of the delivery channel and at least one closed pump volume in the delivery channel; displacing the at least one displaceable seal and the at least one closed pump volume along the delivery channel from the at least one inlet to the at least one outlet by a rotational movement of the eccentric to deliver the liquid; a) setting a liquid quantity to be delivered by the pump; b) determining a temperature of the deformable element with the temperature sensor.

2. A pump for delivering a liquid, the pump comprising: at least one pump housing having at least one inlet, at least one outlet and a cylindrical circumferential surface; an eccentric disposed at said at least one pump housing, said eccentric being rotatable about an axis relative to said at least pump housing; a deformable element disposed between said at least pump housing and said eccentric; said deformable element and said cylindrical circumferential surface forming a delivery channel from said at least one inlet to said at least one outlet; said deformable element being pressed by said eccentric in sections against said at least one pump housing to form at least one displaceable seal of said delivery channel and at least one closed pump volume in said delivery channel; said at least one displaceable seal and said at least one closed pump volume being displaced by a rotational movement of said eccentric along said delivery channel from said at least one inlet to said at least one outlet to deliver the liquid; and at least one temperature sensor for determining a temperature of said deformable element; opposing counter elements mounted on said at least one pump housing and abutting said deformable element, said counter elements sealing said deformable element on said at least one pump housing, one of said counter elements having a channel formed therein for said temperature sensor, said channel opening against said deformable element.

3. The pump according to claim 2, wherein said at least one temperature sensor is an infrared sensor for detecting thermal radiation emanating from said deformable element.

4. The pump according to claim 3, wherein said channel is a radiation channel, the thermal radiation passing along said radiation channel from said deformable element to said infrared sensor.

5. The pump according to claim 2, wherein said at least one temperature sensor is a thermocouple being in contact with said deformable element.

6. The pump according to claim 2, wherein said at least one temperature sensor is a measuring resistor.

7. A motor vehicle, comprising: an internal combustion engine; an exhaust gas treatment apparatus for purifying exhaust gases of said internal combustion engine; and a tank for storing a liquid additive for exhaust gas purification; an injector for feeding the liquid additive to said exhaust gas treatment apparatus; and a pump according to claim 2 for delivering the liquid additive from said tank to said injector.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

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

(2) FIG. 2 shows a section through the deformable element of a described pump,

(3) FIG. 3 shows a section through a first design variant of a described pump,

(4) FIG. 4 shows a section through a second design variant of a described pump,

(5) FIG. 5 shows a section through a third design variant of a described pump,

(6) FIG. 6 shows a flow chart of the described method, and

(7) FIG. 7 shows a motor vehicle having a described pump.

DESCRIPTION OF THE INVENTION

(8) FIG. 1 shows the pump 1 in a three-dimensional view. The pump housing 2 and a coordinate system with an axial direction 24 along the axis 6, a radial direction 28 which lies perpendicularly to the axis 6 and the axial direction 24, and a circumferential direction 32 which is arranged perpendicularly to the radial direction 28 and tangentially with respect to the axis 6 and the axial direction 24 can be seen. Said coordinate system will be used in the following text to describe the spatial arrangement of the components of the pump 1. An inlet 3 and an outlet 4 are situated on the pump housing 2. The eccentric (not shown here) is arranged within the pump housing 2, which eccentric is driven by a drive 27 via a drive shaft 26. The axial direction 24 is oriented along an axis 6, in which both the pump housing 2 with the eccentric (not shown) and the drive 27 are arranged.

(9) FIG. 2 depicts a section through the pump housing 2 of the pump 1. The inlet 3 and the outlet 4 can likewise be seen in said section. The eccentric 5 is arranged within the pump housing 2. The eccentric 5 is divided into an inner eccentric region 29 and an outer bearing ring 30 which are separated from one another by way of a bearing 31. When the eccentric region 29 carries out an eccentric rotational movement, said rotational movement is converted by the bearing 31 into an eccentric tumbling movement of the bearing ring 30. The deformable element 7 and the delivery channel 8 are situated between the eccentric 5 and the pump housing 2. The deformable element 7 is pressed by the eccentric 5 in sections against the pump housing 2, with the result that a displaceable seal 9 is configured. At least one pump volume 10 is delimited within the delivery channel 8 by way of the displaceable seal 9. The pump volume 10 is likewise displaced by way of a rotation of the eccentric 5 and a displacement of the displaceable seal 9, with the result that the delivery of liquid from the inlet 3 to the outlet 4 with a delivery direction 11 takes place. The radial direction 28 and the circumferential direction 32 can likewise be seen in FIG. 2. Depending on how the eccentric 5 is positioned, the displaceable seal 9 has an angular position 15. Said angular position 15 can be used to increase the accuracy of the delivery of liquid by way of the pump 1 because, depending on where the angular position 15 of the displaceable seal 9 or the eccentric 5 is situated, the delivery quantity of the pump is different during a predefined movement of the eccentric 5 by a defined angular section.

(10) Moreover, the pump 1 has a stationary seal 25 between the outlet 4 and the inlet 3, by way of which stationary seal 25 a return flow of liquid from the outlet 4 to the inlet 3 through the pump is prevented. In the exemplary embodiment which is described here, the stationary seal 25 is realized by virtue of the fact that a pin 22 is inserted into the deformable element 7, which pin 22 presses the deformable element 7 in the region of the stationary seal 25 in a stationary manner against the pump housing 2. By way of the pin 22, the deformable element 7 is clamped onto the pump housing. Further variants of stationary seals 25 are conceivable. For example, the deformable element 7 can be adhesively bonded to the pump housing 2 in the region of the stationary seal 25.

(11) FIGS. 3 to 5 show the cross section from FIG. 2 which is marked using B-B of three different design variants of a described pump 1. In each case, the pump housing 2, the eccentric 5 with the eccentric region 29, the bearing ring 30 and the bearing 31, and the deformable element 7 between the pump housing 2 and the eccentric 5 can be seen. The pump housing 2 has in each case one counter holder 21 on both sides, the two counter holders 21 enclosing and axially sealing the deformable element 7. It is shown by way of example in the figures that the counter holders 21 are fastened to a main component of the pump housing 2 with the aid of bolts 23. At the same time, bracing and sealing of the deformable element 7 on the pump housing 2 can also be realized by way of said bolts 23. The axial direction 24 and the radial direction 28 can also be seen in FIGS. 3, 4 and 5. The delivery channel 8 with a pump volume 10 is situated in each case between the deformable element 7 and the pump housing 2.

(12) In accordance with FIG. 3, a temperature sensor 16 exists which is configured as an infrared sensor 17 and can measure the temperature of the deformable element 7 through a radiation channel 18 which is configured in the pump housing 2. FIG. 4 also shows a gap 42 between the pump housing 2 and the eccentric 5. In a further design variant of the pump 1, the radiation channel 18 can also run through said gap 42. In accordance with FIG. 4, a thermocouple 19 which is in contact with the deformable element 7 exists as temperature sensor 16. FIG. 5 shows a measuring resistor 20 which extends through the deformable element 7 as temperature sensor 16.

(13) FIG. 6 illustrates the sequence of the described method with the method steps a), b), c) and d). In step a), a liquid quantity 14 is determined which is to be delivered by way of the pump. In step b), a temperature 12 of the deformable element is determined. The information about the liquid quantity 14 and the information about the temperature 12 are used in step c), in order to determine the parameter 13. In addition, an angular position 15 of the eccentric can also be used in step c), in order to determine the parameter 13. In step c), a characteristic diagram which is stored in a control unit can be used to this end. In step d), the fixed liquid quantity 14 and the parameter 13 are used to correspondingly describe the delivery unit and to deliver liquid.

(14) FIG. 7 shows a motor vehicle 36 having an internal combustion engine 37 and an exhaust gas treatment apparatus 38 for purifying the exhaust gases of the internal combustion engine 37. An SCR catalytic converter 39 for carrying out the method of selective catalytic reduction is arranged within the exhaust gas treatment apparatus 38. The exhaust gas treatment apparatus 38 can be fed liquid additive with the aid of an injector 34. The injector 34 is supplied with liquid additive from a tank 35 via a line 33. This takes place with the aid of a pump 1.

LIST OF DESIGNATIONS

(15) 1 Pump 2 Pump housing 3 Inlet 4 Outlet 5 Eccentric 6 Axis 7 Deformable element 8 Delivery channel 9 Displaceable seal 10 Pump volume 11 Delivery direction 12 Temperature 13 Parameter 14 Liquid quantity 15 Angular position 16 Temperature sensor 17 Infrared sensor 18 Radiation channel 19 Thermocouple 20 Measuring resistor 21 Counterholder 22 Pin 23 Bolt 24 Axial direction 25 Stationary seal 26 Drive shaft 27 Drive 28 Radial direction 29 Eccentric region 30 Bearing ring 31 Bearing 32 Circumferential direction 33 Line 34 Injector 35 Tank 36 Motor vehicle 37 Internal combustion engine 38 Exhaust gas treatment apparatus 39 SCR catalytic converter 40 Circumferential face 41 Gap