Thermal fuel level detector

Claim 2

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a substrate; a self-heating temperature sensing resistor means formed on said substrate and having a relatively large temperature resistance coefficient and a relatively small resistance value, for detecting its resistance value as a function of its temperature, and self-heating temperature sensing resistor means being adapted to be dipped in said fuel remaining in said fuel tank; a temperature compensating temperature sensing resistor means formed on said substrate and having a temperature resistance coefficient substantially equal to a temperature resistance coefficient of said self-heating temperature sensing resistor means and a relatively large resistance value, said temperature compensating sensing resistor means being adapted to be dipped in said fuel to detect an atmospheric temperature within said fuel tank and a temperature of said fuel; and an electrical circuit means connected to both said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means for compensating said resistance value detected by said self-heating temperature sensing resistor means for variations in atmospheric temperature and in said temperature of said fuel, whereby a change in said resistance value of said self-heating temperature sensing resistor means responsive to cooling caused by heat of vaporization on a portion thereof which is dipped in said fuel is detected as a differential output voltage which provides an indication of said level of fuel remaining in said fuel tank.

Claim 3

A thermal fuel level detector as set forth in claim 1, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means are substantially equal in length.

Claim 4

A thermal fuel level detector as set forth in claim 1, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means are made of platinum, gold, silver, palladium, ruthenium oxide, copper, nickel, steel, chrome, cobalt or an alloy thereof.

Claim 5

A thermal fuel level detector as set forth in claim 1, wherein each of said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means includes a resistor film having its outer surface protected with an insulator such as glass, resin or the like.

Claim 6

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a first temperature sensing element including, a first substrate; and a self-heating temperature sensing resistor means formed on said first substrate and having a relatively high temperature resistance coefficient, for detecting its resistance value as a function of its temperature, said self-heating temperature sensing resistor means being adapted to be dipped in said fuel remaining in said fuel tank; a second temperature sensing element including, a second substrate; and a temperature compensating temperature sensing resistor means formed on said second substrate and having a temperature resistance coefficient substantially equal to a temperature resistance coefficient of said self-heating temperature sensing resistor means, for detecting an ambient temperature within said fuel tank and a temperature of said fuel, said temperature compensating temperature sensing resistor means being dipped in said fuel; and an electrical circuit means connected to both said first sensing element and said second sensing element to energize both said first sensing element and said second sensing element, for compensating said resistance value detected by said first temperature sensing element for variations in ambient temperature and in said temperature of said fuel, whereby a change in said resistance value of said self-heating temperature sensing resistor means responsive to cooling caused by heat of vaporization on a portion thereof which is dipped in said fuel is detected as a differential output voltage which provides an indication of said level of fuel remaining in said fuel tank.

Claim 7

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a first temperature sensing element including, a first substrate; and a self-heating temperature sensing resistor means formed on said first substrate and having a relatively high temperature resistance coefficient, for detecting its resistance value as a function of its temperature, said self-heating temperature sensing resistor means being adapted to be dipped in said fuel remaining in said fuel tank; a second temperature sensing element including, a second substrate; and a temperature compensating temperature sensing resistor means formed on said second substrate and having a temperature resistance coefficient substantially equal to a temperature resistance coefficient of said self-heating temperature sensing resistor means, for detecting an ambient temperature within said fuel tank and a temperature of said fuel, said temperature compensating temperature sensing resistor means being dipped in said fuel; and an electrical circuit means connected to both said first sensing element and said second sensing element to energize both said first sensing element and said second sensing element, for compensating said resistance value detected by said first temperature sensing element for variations in ambient temperature and in said temperature of said fuel, whereby a change in said resistance value of said self-heating temperature sensing resistor means responsive to cooling caused by heat of vaporization on a portion thereof which is dipped in said fuel is detected as a differential output voltage which provides an indication of said level of fuel remaining in said fuel tank.

Claim 8

A thermal fuel level detector as set forth in claim 5, wherein said self-heating temperature resistor means of said first temperature sensing element is composed of a plurality of chip-shaped resistors which are formed on said substrate and which have a relatively large temperature resistance coefficient.

Claim 9

A thermal fuel level detector as set forth in claim 6, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means are substantially equal in length.

Claim 10

A thermal fuel level detector as set forth in claim 5, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means are made of platinum, gold, silver, palladium, ruthenium oxide, copper, nickel, steel, chrome, cobalt or an alloy thereof.

Claim 11

A thermal fuel level detector as set forth in claim 5, wherein each of said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means includes a resistor film having its outer surface protected with an insulator such as glass, resin or the like.

Claim 12

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a first temperature sensing resistance element including, a first substrate; and a self-heating temperature sensing resistor means comprising a plurality of chip-like self-heating temperature resistors mounted on said first substrate and having a relatively large temperature resistance coefficient, for detecting their own resistance values as a function of their temperatures, said first temperature sensing element being adapted to be dipped in said fuel, a second temperature sensing resistance element including, a second substrate; and a temperature compensating temperature sensing resistor means comprising a plurality of chip-like temperature compensating sensing resistors mounted on said second substrate for detecting an ambient temperature within said fuel tank and a temperature of said fuel, said second temperature sensing element being dipped in said fuel, and an electrical circuit means connected to said first temperature sensing element and said second temperature sensing element, for energizing the same and for compensating said resistance value detected by said first temperature sensing element for variations in the ambient temperature and in said temperature of said fuel, whereby a variation in said resistance of said self-heating temperature sensing resistor means responsive to cooling caused by heat of evaporation on a portion thereof dipped in said fuel is detected as a differential output voltage which provides an indication of said level of said fuel remaining in said fuel tank.

Claim 13

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a first temperature sensing resistance element including, a first substrate; and a self-heating temperature sensing resistor means comprising a plurality of chip-like self-heating temperature resistors mounted on said first substrate and having a relatively large temperature resistance coefficient, for detecting their own resistance values as a function of their temperatures, said first temperature sensing element being adapted to be dipped in said fuel, a second temperature sensing resistance element including, a second substrate; and a temperature compensating temperature sensing resistor means comprising a plurality of chip-like temperature compensating sensing resistors mounted on said second substrate for detecting an ambient temperature within said fuel tank and a temperature of said fuel, said second temperature sensing element being dipped in said fuel, and an electrical circuit means connected to said first temperature sensing element and said second temperature sensing element, for energizing the same and for compensating said resistance value detected by said first temperature sensing element for variations in the ambient temperature and in said temperature of said fuel, whereby a variation in said resistance of said self-heating temperature sensing resistor means responsive to cooling caused by heat of evaporation on a portion thereof dipped in said fuel is detected as a differential output voltage which provides an indication of said level of said fuel remaining in said fuel tank.

Claim 14

A thermal fuel level detector as set forth in claim 10, wherein said first temperature sensing element and said second temperature sensing element are mounted on one and the same substrate comprising said first and second substrates.

Claim 15

A thermal fuel level detector as set forth in claim 10, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means are made of platinum, gold, silver, palladium, ruthenium oxide, copper, nickel, steel, chrome, cobalt or an alloy thereof.

Claim 16

A thermal fuel level detector as set forth in claim 10, wherein said self-heating temperature sensing resistor means and said temperature compensating temperature sensing resistor means includes a resistor film having its outer surface protected with an insulator such as glass, resin or the like.

Claim 17

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a substrate; a plurality of self-heating temperature sensing resistor means arranged on said substrate in several stages at predetermined intervals and each having a large temperature coefficient, each of said plurality of self-heating temperature sensing resistor means for detecting its resistance as a function of its temperature, said plurality of self heating temperature sensing resistor means being connected in parallel with each other and being adapted to be at least partially dipped in said fuel; a plurality of second resistor means each having a small temperature resistance coefficient, said plurality of second resistor means being connected in series respectively to said self-heating temperature sensing resistor means and being at least partially dipped in said fuel; and an electrical circuit means connected to said plurality of self-heating temperature sensing resistor means and said plurality of second resistor means for detecting a variation in the resistance of said self-heating temperature sensing resistor means responsive to cooling caused by heat of evaporation on a portion thereof which is dipped in said fuel, as a variation in differential output voltage which provides an indication of said level of fuel remaining in said fuel tank.

Claim 18

A thermal fuel level detector for detecting a level of fuel remaining in a fuel tank, comprising: a substrate; a plurality of self-heating temperature sensing resistor means arranged on said substrate in several stages at predetermined intervals and each having a large temperature coefficient, each of said plurality of self-heating temperature sensing resistor means for detecting its resistance as a function of its temperature, said plurality of self heating temperature sensing resistor means being connected in parallel with each other and being adapted to be at least partially dipped in said fuel; a plurality of second resistor means each having a small temperature resistance coefficient, said plurality of second resistor means being connected in series respectively to said self-heating temperature sensing resistor means and being at least partially dipped in said fuel; and an electrical circuit means connected to said plurality of self-heating temperature sensing resistor means and said plurality of second resistor means for detecting a variation in the resistance of said self-heating temperature sensing resistor means responsive to cooling caused by heat of evaporation on a portion thereof which is dipped in said fuel, as a variation in differential output voltage which provides an indication of said level of fuel remaining in said fuel tank.

Claim 19

A thermal fuel level detector as set forth in claim 14, wherein said plurality of self-heating temperature sensing resistor means are chip-like temperature sensing resistors which are formed on an insulating substrate and which are mounted on said substrate in multiple stages, being separated as predetermined intervals.

Claim 20

A thermal fuel level detector as set forth in claim 14, wherein each of said self-heating temperature resistor means and said second resistor means are made of platinum, gold, silver, palladium, ruthenium oxide, copper, nickel, steel, chrome, cobalt or an alloy thereof.

Claim 21

A thermal fuel level detector as set forth in claim 14, wherein each of said self-heating temperature sensing resistor means and said second resistor means includes a resistor film having its outer surface protected with an insulator such as glass, resin or the like.

Claim 22

A thermal fuel level detector as set forth in claim 10, wherein said first substrate and said second substrate each comprise a flexible substrate made of a polyamide or the like which has a low thermal capacity and which is applied on a base made of ceramic or the like by a printing and sintering process.