HEATER FOR A DEVICE FOR PROVIDING A LIQUID ADDITIVE

Abstract

The invention relates to a heater for a device for providing a liquid additive in a motor vehicle, comprising at least one switchable resistance heating element, which is connected in series with at least one switch element, by means of which the at least one resistance heating element can be activated and deactivated, and comprising at least one permanent resistance heating element, which is connected in parallel with the at least one switchable resistance heating element and the at least one switch element.

Claims

1. A heater for a device for supplying a liquid additive in a motor vehicle comprising: at least one resistance heating element; at least one switch element; at least one switchable resistance heating element which is connected in series with the at least one switch element, where the at least one switch element is used to activate and deactivate the at least one switchable resistance heating element; and at least one permanent resistance heating element which is connected in parallel with respect to the at least one switchable resistance heating element and the at least one switch element.

2. The heater according to claim 1, wherein the electrical resistances of the at least one switchable resistance heating element and of the at least one permanent resistance heating element are configured such that a proportion of between 70% and 95% of the heating power of the heater is generated by the at least one switchable resistance heating element when the at least one switchable resistance heating element is activated.

2. The heater according to claim 1, further comprising: at least one temperature sensor; and at least one control component used to control the at least one switch element and the at least one switchable resistance heating element as a function of a temperature determined by the at least one temperature sensor.

3. The heater according to claim 1, further comprising: a heating foil with a surface; wherein the at least one switchable resistance heating element and the at least one permanent resistance heating element are arranged as conductor paths on the heating foil.

5. The heater according to claim 3, wherein the heating foil (9) is flexible.

6. The heater according to claim 1, further comprising a plurality of switchable resistance heating elements and a plurality of switch elements assigned to a corresponding one of the plurality of in switchable resistance heating elements, wherein the plurality of switchable resistance heating elements are arranged in different surface sections of the heater.

7. The heater according to claim 6, wherein each of the plurality of switchable resistance heating elements is assigned at least one corresponding temperature sensor, and each of the plurality of switchable resistance heating elements are activated and deactivated, as a function of a temperature determined by the at least one corresponding temperature sensor, and one of the plurality of switch elements and at least one control component.

8. The heater according to claim 1, further comprising a device for providing liquid additive in a motor vehicle, wherein the at least one electric heater is used to heat the liquid additive in the device.

9. (canceled)

10. The heater according to claim 8, the device for providing liquid additive to a motor vehicle further comprising a tank for storing the liquid additive; and a tank wall, the tank wall being part of the tank; wherein the at least one electric heater is arranged on an outer side of the tank wall such that liquid additive in the tank is heated by the at least one heater through the tank wall.

11. The heater according to claim 1, further comprising an exhaust gas treatment device, the exhaust gas treatment device being part of the motor vehicle.

12. The heater according to claim 11, the motor vehicle further comprising an internal combustion engine, the exhaust-gas treatment device for purifying the exhaust gases of the internal combustion engine; and a device for supplying liquid additive for the exhaust-gas treatment device, the heater being used with said device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0051] FIG. 1: shows a first design variant of a described heating foil,

[0052] FIG. 2: shows a second design variant of a described heating foil,

[0053] FIG. 3: shows a device having a described heating foil,

[0054] FIG. 4: shows a section through a housing of a delivery unit having a described heating foil, and

[0055] FIG. 5: shows a motor vehicle having a device for supplying liquid additive, said device having a described heating foil.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] 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.

[0057] FIGS. 1 and 2 each illustrate the heater 1, which is in the form of a heating foil 9. It can be seen that the heating foil 9 has a surface 10.

[0058] FIG. 1 and FIG. 2 each show electrical contacts 12 by way of which the heater 1 can be supplied with power. Also shown are conductor paths 11 on the heating foil, which conductor paths form switchable resistance heating elements 4 and permanent resistance heating elements 6. Also shown are switch elements 5, (electronic) control components 8 and temperature sensors 7.

[0059] In the design variant of FIG. 1, precisely one permanent resistance heating element 6 and one switchable resistance heating element 4 are provided.

[0060] In the design variant of FIG. 2, in each case two supply conductor paths 23 are provided via which multiple switchable resistance heating elements 4, which each have a switch element 5, an electronic control component 8 and a temperature sensor 7, can be energized. Furthermore, in the design variant in FIG. 2, there is precisely one permanent resistance heating element 6. It can be seen that the individual switchable resistance heating elements 4 are arranged in each case in surface sections 13 of a surface 10 of the heater 1.

[0061] The design variants of the heater 1 illustrated in FIGS. 1 and 2 are in particular not restricted with regard to the arrangement of temperature sensors 7, control components 8 and switch elements 5. Said elements (switch elements 5, control components 8 and temperature sensors 7) may also be arranged outside the heater 1, for example on other components of a device for supplying liquid additive.

[0062] Furthermore, FIGS. 1 and 2 are not restricted with regard to the arrangements and number of switchable resistance heating elements 4 and permanent resistance heating elements 6 illustrated therein. Resistance heating elements may be arranged on the heating foil as desired. What are particularly suitable in each case are resistance heating elements that run in meandering fashion, because by means of meandering structures, it is possible to realize relatively high electrical resistances and a uniform distribution of the electrical heating power.

[0063] FIG. 3 shows a tank 15 for a liquid additive, which tank has a tank wall 29. A housing 14, in which a pump 22 is situated, is integrated into the tank 15 in the region of a tank base. The pump 22 can extract liquid additive 28 from the tank 15 at an intake point 20. Said liquid additive is supplied by the pump 22 to a supply port 21. On the inner side 16 of the housing 14 there is situated a described heater 1, which extends in areal fashion along the inner side 16 of the housing. In

[0064] FIG. 3, the liquid additive is present in the tank in the form of frozen additive 27. Within the frozen additive 27 there is formed an ice cavity 19 which has been generated by the heater 1 by virtue of the frozen additive 27 having been melted to form liquid additive 28.

[0065] FIG. 4 shows the section A-A, indicated in FIG. 3, through the housing 14 of the device 2. It is possible to see the heater 1 with the electrical contacts 12 and the pump 22 and the intake point 20. The heater 1 lies against an inner side 16 of the housing 14, wherein the inner side of the housing 14 forms an outer side 30 of the tank 15.

[0066] FIG. 5 shows a motor vehicle 3 having an internal combustion engine 17 and having an exhaust-gas treatment device 18 for the purification of the exhaust gases of the internal combustion engine 17. In the exhaust-gas treatment device 18 there is arranged an SCR catalytic converter 26 for carrying out the method of selective catalytic reduction. A liquid additive can be fed from a tank 15 to the exhaust-gas treatment device 18 by means of a metering device 25. Liquid additive is supplied to the metering device 25 via a line 24 by a device 2 arranged in the tank 15.

[0067] 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.