Heater plug for diesel engines

Claim 2

In a diesel engine having a zone for heating or reheating a fuel or air or a mixture thereof, said zone having a heater plug, said heater plug employed as a reheating cold-starting aid for said fuel or air or a mixture thereof, the improvement wherein said heater plug comprises an electrically conductive heater coil connected to an electrically conductive terminal pin, said terminal pin maintained in gas-type manner at least in part within and insulated from an electrically conductive plug shell, at least the surface of said heater coil formed of a metal of the platinum group, said heater coil supported by a heat resistant electrically insulating rod-like supporting body attached to said terminal pin, said heater coil being surrounded by a heat-resistant electrically conductive protective tube made of a metal and electrically connected at its other end to the end of said electrically conductive protective tube, said protective tube having openings over its circumference of number and size sufficient to permit fuel and air to pass to said heater coil, said protective tube having an opening at one end, said electrically conductive heater coil being electrically insulated along said protective tube, except for the terminal connecting portion.

Claim 3

In a diesel engine according to claim 1, wherein said heater coil is formed by a wire winding on said supporting body.

Claim 4

In a diesel engine according to claim 1, wherein said heater coil is formed of a thin layer applied helically to said supporting body.

Claim 5

In a diesel engine according to claim 3, wherein said heater coil comprises a vapor deposited, layer.

Claim 6

A diesel engine according to claim 3, wherein said heater coil comprises a sputtered layer.

Claim 7

A diesel engine according to claim 3, wherein said heater coil comprises an imprinted layer.

Claim 8

A diesel engine according to claim 3, wherein said heater coil comprises a flame sprayed layer.

Claim 9

A diesel engine according to claim 3, wherein said heater coil comprises a galvanically precipitative layer.

Claim 10

A diesel engine according to claim 3, wherein said heater coil comprises a chemically precipitated layer.

Claim 11

In a diesel engine according to claim 1, wherein said intermediate layer is disposed between heater coil and said supporting body, at least over the area of the coil.

Claim 12

In a diesel engine according to claim 1, wherein said heater coil is disposed in a baked-on layer on said supporting body.

Claim 13

A diesel engine according to claim 1, wherein the heater coil is formed in its entirety of at least one member selected from the group consisting of a metal of the platinum group and an alloy comprising at least member of the platinum group.

Claim 14

A diesel engine according to claim 1, wherein the heater coil is formed of a member selected from the group consisting of a metal and an alloy of such metal wherein said metal is selected from the group consisting of niobium, tantalum, molybdenum and tungsten, and is covered with a layer of a material selected from the group consisting of a metal from the platinum group and an alloy of a member of the platinum group.

Claim 15

A diesel engine according to claim 13, wherein the metal of said heater coil is in the form of an alloy.

Claim 16

In a diesel engine according to claim 1, wherein said heater plug further comprises a glass seal disposed in insulating relationship between said terminal pin, said supporting body, and said electrically conductive heating coil on the one hand from said protective tube on the other.

Claim 17

In a diesel engine according to claim 1, wherein said protective tube for the heater coil extends beyond the supporting body and is open at least at the free end of the supporting body.

Claim 18

In a diesel engine according to claim 16, wherein the protective tube is perforated.

Claim 19

In a diesel engine according to claim 17, wherein the heater coil is fastened at one of its ends to the protective tube, which in turn is fastened in said plug shell, the other end of the heater coil being fastened to the terminal pin.

Claim 20

In a diesel engine according to claim 18, wherein said protective tube is force-fitted into said electrically conductive shell.

Claim 21

A diesel engine according to claim 1, wherein said supporting body is formed of a member selected from the group consisting of a ceramic material, a quartzose, vitreous silica, a high silica glass and a vitrified ceramic material.

Claim 22

In a diesel engine according to claim 1, wherein the wire of said heater coil has a diameter of 200 to 400μ.

Claim 23

In a diesel engine according to claim 21, wherein the wire of said heater coil comprises a platinum-rhodium alloy where the rhodium content is up to 40 percent by weight.

Claim 24

In a diesel engine according to claim 1, wherein the wire of said heater core over which there is disposed a cladding, said cladding has a thickness of from 5 to 50μ and said core has a diameter of 150 to 400μ.

Claim 25

In a diesel engine according to claim 23, wherein said cladding is made of platinum and said core is made of molybdenum or tungsten.

Claim 26

In a diesel enging according to claim 24, wherein said core has a diameter of 250 to 300μ.

Claim 27

In a diesel engine according to claim 24, wherein said cladding has a thickness of about 25μ.

Claim 28

A diesel engine according to claim 23, wherein said cladding is made of an alloy comprising at least one metal from the platinum group and said core is made of at least one material selected from the group consisting of molybdenum and tungsten.

Claim 29

In a diesel engine according to claim 1, wherein said heater coil is in the form a strip, which strip comprises a core and a cladding, the core having a cross-sectional area of about 0.02 to 0.10 mm 2 and the cladding has a thickness of 5 to 50μ.

Claim 30

In a diesel engine according to claim 28, wherein said core comprises molybdenum or tungsten and said cladding is formed of platinum comprising at least one metal of the platinum group.

Claim 31

A diesel engine according to claim 29, wherein said platinum is in the form of an alloy.

Claim 32

In a diesel engine according to claim 1, wherein the heater coil is formed from a layer which is helically disposed on said supporting body, said layer having a cross-sectionaly area of about 0.02 to 0.10 mm 2 .

Claim 33

A diesel engine according to claim 1, wherein said heater coil comprises a core of a ceramic material over which is disposed a material selected from the group consisting of a platinum metal and an alloy of a platinum metal.

Claim 34

In a diesel engine having a zone for heating or reheating a fuel or air or a mixture thereof, said zone having a heater plug, said heater plug employed as a heating cold starting aid for said fuel or air or a mixture thereof, the improvement wherein said heater plug comprises an electrically conductive heater coil connected to an electrically conductive terminal pin, said terminal pin maintained in gas-tight manner at least in part within and insulated from an electrically conductive plug shell, at least the surface of said heater coil formed of a metal of the platinum group, said heater coil supported by a heat-resistant, electrically insulating, tubular supporting body attached to said terminal pin, said heater coil being surrounded by a heat resistant, electrically conductive protective tube made of a metal and electrically conductive at its other end to the end of said electrically conductive protective tube, said protective tube having openings over its circumference of number and size suffficient to permit fuel and air to pass to said heater coil, said protective tube having an opening at one end, said electrically conductive heater coil being electrically insulated along said protective tube, except for the terminal connecting portion.

Claim 35

In a diesel engine having a zone for heating or reheating a fuel or air or a mixture thereof, said zone having a heater plug, said heater plug employed as a heating cold starting aid for said fuel or air or a mixture thereof, the improvement wherein said heater plug comprises an electrically conductive heater coil connected to an electrically conductive terminal pin, said terminal pin maintained in gas-tight manner at least in part within and insulated from an electrically conductive plug shell, at least the surface of said heater coil formed of a metal of the platinum group, said heater coil supported by a heat-resistant, electrically insulating, tubular supporting body attached to said terminal pin, said heater coil being surrounded by a heat resistant, electrically conductive protective tube made of a metal and electrically conductive at its other end to the end of said electrically conductive protective tube, said protective tube having openings over its circumference of number and size suffficient to permit fuel and air to pass to said heater coil, said protective tube having an opening at one end, said electrically conductive heater coil being electrically insulated along said protective tube, except for the terminal connecting portion.