High power density insulated exhaust heating system

Patent metadata

Field	Value
Publication number	US-11686232-B2
Application number	US-202217873224-A
Country	US
Kind code	B2
Filing date	Jul 26, 2022
Priority date	Oct 31, 2016
Publication date	Jun 27, 2023
Grant date	Jun 27, 2023

Abstract

An exhaust gas heating unit for an engine includes a housing and a heating element. The housing includes a tubular peripheral wall and has an interior hollow space. The heating element has first and second ends and extends longitudinally therebetween to form a spiral shape within the interior hollow space. The heating element includes a thermally conductive sheath, an electrically conductive resistance element that extends longitudinally within the external sheath, and an electrically insulating material disposed about the resistance element between the resistance element and the sheath. A heat transfer member is positioned within the interior hollow space and is formed from one or more strips of thermally conductive material. The strips contact the external sheath at a plurality of locations between the first end and the second end. The heat transfer member has a corrugated shape that follows the spiral shape of the heating element.

First claim

What is claimed is:

1. An exhaust gas heating unit for an exhaust system of an internal combustion engine, the exhaust gas heating unit comprising:
a tubular housing comprising an outer peripheral wall defining a tubular shape and having an interior hollow space; and
a heating element that has a first end and a second end and extends longitudinally between the first end and the second end to form a spiral shape within the interior hollow space, wherein the heating element comprises:
an external sheath, the external sheath formed of a thermally conductive material;
an electrically conductive resistance element that extends longitudinally within the external sheath; and
electrically insulating material disposed about the resistance element between the resistance element and the sheath; and

a heat transfer member positioned within the interior hollow space, the heat transfer member being formed from one or more strips of thermally conductive material,
wherein the one or more strips contact the external sheath at a plurality of locations between the first end and the second end, and
wherein the heat transfer member has a corrugated shape that follows the spiral shape of the heating element.

2. The exhaust gas heating unit according to claim 1 , wherein the first end is connected to a first power pin and the second end is connected to a second power pin.

3. The exhaust gas heating unit according to claim 2 , wherein the first and second power pins extend outside the interior hollow space of the tubular housing.

4. The exhaust gas heating unit according to claim 1 , wherein a first section of the at least one strip is positioned radially outward of a second section of the at least one strip, the second section being further along the spiral shape than the first section.

5. The exhaust gas heating unit according to claim 1 further comprising a spacer disposed in a gap that is radially between the heat transfer member and the tubular housing.

6. The exhaust gas heating unit according to claim 5 , wherein the spacer is configured to inhibit exhaust gas flow through the gap.

7. The exhaust gas heating unit according to claim 1 further comprising an end piece disposed at the second end proximate a center of the interior hollow space.

8. The exhaust gas heating unit according to claim 7 , wherein the heat transfer member is secured to the end piece.

9. The exhaust gas heating unit according to claim 1 , wherein the external sheath is configured to loosely contact the at least one strip.

10. The exhaust gas heating unit according to claim 1 , wherein the at least one strip is fixed to the external sheath at the plurality of locations.

11. The exhaust gas heating unit according to claim 1 , wherein the plurality of locations are spaced at a spacing along a length of the strip, wherein the spacing is less than ten times an outside diameter of the external sheath.

12. The exhaust gas heating unit according to claim 11 , wherein a natural frequency of vibration for sections of the heater element between adjacent two locations of the plurality of locations is greater than 400 Hz.

13. The exhaust gas heating unit according to claim 1 , wherein the at least one strip includes a single strip that follows the spiral path from the second end proximate a center of the interior hollow space to the first end proximate the outer peripheral wall.

14. An exhaust gas heating unit for an exhaust system of an internal combustion engine, the exhaust gas heating unit comprising:
a tubular housing comprising an outer peripheral wall defining a tubular shape and having an interior hollow space; and
a heating element that has a first end proximate the outer peripheral wall and a second end proximate a center of the interior hollow space, the heating element extending longitudinally between the first end and the second end along a spiral path within the interior hollow space, wherein the heating element comprises:
an external sheath, the external sheath formed of a thermally conductive material;
an electrically conductive resistance element that extends longitudinally within the external sheath; and
electrically insulating material disposed about the resistance element between the resistance element and the sheath; and

a heat transfer member positioned within the interior hollow space, the heat transfer member being formed from one or more strips of thermally conductive material,
wherein the one or more strips are coupled to the external sheath at a plurality of locations between the first end and the second end, and
wherein the heat transfer member has a shape that follows the spiral shape of the heating element and includes a plurality of substantially “V-shaped” segments, each V-shaped segment is associated with a bent portion of the one or more strips.

15. The exhaust gas heating unit according to claim 14 further comprising an end piece disposed at the second end and secured to the heat transfer member.

16. The exhaust gas heating unit according to claim 14 , wherein the heat transfer member is coupled to the external sheath, at least in part, through a frictional engagement.

17. The exhaust gas heating unit according to claim 14 further comprising a spacer disposed in a gap that is radially between an outermost section of the heat transfer member and the tubular housing, the spacer being configured to inhibit exhaust gas flow through the gap.

18. The exhaust gas heating unit according to claim 14 , wherein a natural frequency of vibration for sections of the heater element between adjacent two locations of the plurality of locations is greater than 400 Hz.

19. An exhaust gas heating unit for an exhaust system of an internal combustion engine, the exhaust gas heating unit comprising:
a tubular housing comprising an outer peripheral wall defining a tubular shape and having an interior hollow space; and
a heating element that has a first end proximate the outer peripheral wall and a second end proximate a center of the interior hollow space, the heating element extending longitudinally between the first end and the second end along a spiral path within the interior hollow space, wherein the heating element comprises:
an external sheath, the external sheath formed of a thermally conductive material;
an electrically conductive resistance element that extends longitudinally within the external sheath; and
electrically insulating material disposed about the resistance element between the resistance element and the sheath;

a heat transfer member positioned within the interior hollow space, the heat transfer member being formed from one or more strips of thermally conductive material; and
a spacer disposed in a gap that is radially between an outermost section of the heat transfer member and the tubular housing, the spacer being configured to inhibit exhaust gas flow through the gap,
wherein the one or more strips are fixed to the external sheath at a plurality of locations between the first end and the second end,
wherein the heat transfer member has a corrugated shape that follows the spiral shape of the heating element, and
wherein the first end is connected to a first power pin and the second end is connected to a second power pin, the first and second power pins extending outside the interior hollow space of the tubular housing.

20. The exhaust gas heating unit according to claim 19 further comprising an end piece disposed at the second end and secured to the heat transfer member.

Assignees

• Watlow Electric Mfg

Inventors

• Everly Mark D
• Ohse Jeremy
• Culbertson David P
• Williams Richard T
• Jambor George
• Wilson Jacob

Classifications

• F01N2450/22

  by welding or brazing · CPC title

• F01N3/027

  using electric or magnetic heating means · CPC title

• H05B2203/014

  Heaters using resistive wires or cables not provided for in H05B3/54 · CPC title

• H05B3/48

  heating conductor embedded in insulating material · CPC title

• F23G7/00

  Incinerators or other apparatus for consuming industrial waste, e.g. chemicals (incinerator closets A47K11/02; oxidation of sludge C02F11/06; burners in general, burner details F23D; incinerating radioactive waste G21F9/00) · CPC title