Level sensor

Claim 2

A liquid-level sensor for sensing the level of liquid in a container, comprising: a. a holder adapted for mounting in the wall of the container, b. a sealed metal can affixed to one side of said holder, c. a sensing element of semiconductor material mounted within the can on a metal end face of the wall of said can, d. electrical leads which protrude from the opposite end of said can and extend into said one side of said holder, which leads are electrically connected to said sensing element, and e. at least one protective lug of said holder which projects at said one side of said holder at least as far as does said can and which only partially surrounds the side of said can to define a free passage for liquid across an outer face of the wall of said can.

Claim 3

A liquid-level sensor according to claim 1, in which said can is arranged between two diametrically-opposed protective lugs of said holder.

Claim 4

A liquid-level sensor according to claim 1, in which said leads extending into said holder affix said can to said holder.

Claim 5

A liquid-level sensor according to claim 3, in which said leads where they extend from said can to said holder comprise an electrically insulating coating.

Claim 6

A liquid-level sensor according to claim 3, in which said leads extend into long metal eyelets which are present in said holder and which extend from said one side of said holder to the opposite side.

Claim 7

A liquid-level sensor according to claim 5, in which said eyelets form electrical terminals at said opposite side of said holder.

Claim 8

A liquid-level sensor according to claim 1, in which said holder is of moulded plastics material.

Claim 9

A liquid-level sensor according to claim 7, in which said holder includes a shoulder portion having thereon a small projection suitable for ultrasonic welding to the wall of said container.

Claim 10

A liquid level sensor for sensing the level of liquid in a container comprising, an insulating holder adapted for mounting in a wall of the container, an encapsulated sensing element affixed to one side of said holder, the sensing element being made of semiconductor material subject only to self-heating by means of a pair of electrical leads electrically connected to said sensing element and protruding from said encapsulation and extending into said one side of the holder, the encapsulation of the sensing element comprising a wall the inner face of whiCh is adjoined by the sensing element to permit heat exchange between the sensing element and the liquid when the liquid in the container is at a level to contact the sensor, and at least one protective lug of said holder which projects at said one side of said holder at least as far as said encapsulated sensing element and which only partially surrounds the side of said encapsulated element to define a free passage for liquid across an outer face of said wall of the encapsulation.

Claim 11

A liquid level sensor for sensing the level of liquid in a container comprising, an insulating holder adapted for mounting in a wall of the container, an encapsulated sensing element affixed to one side of said holder, the sensing element being made of semiconductor material subject only to self-heating by means of a pair of electrical leads electrically connected to said sensing element and protruding from said encapsulation and extending into said one side of the holder, the encapsulation of the sensing element comprising a wall the inner face of whiCh is adjoined by the sensing element to permit heat exchange between the sensing element and the liquid when the liquid in the container is at a level to contact the sensor, and at least one protective lug of said holder which projects at said one side of said holder at least as far as said encapsulated sensing element and which only partially surrounds the side of said encapsulated element to define a free passage for liquid across an outer face of said wall of the encapsulation.

Claim 12

A liquid level sensor as claimed in claim 9 wherein the encapsulation material comprises a glass coating that seals the semiconductor material from the liquid in the container.

Claim 13

A liquid level sensor for sensing the level of liquid in a container comprising, a holder composed of electrically insulating material and adapted for mounting in a wall of the container, said holder comprising first and second main body portions with connecting struts therebetween, two long metal eyelets extending from said first main body portion to said second main body portion, an encapsulated sensing element fixed to the side of said first main body portion that is remote from said second main body portion, protective means protruding from said side of the holder to provide mechanical protection for said encapsulated sensing element, and two electrical leads protruding from the encapsulation of the sensing element and electrically connected to said sensing element, each of said leads extending into an associated one of said metal eyelets at said side of said first main body portion with said associated metal eyelet being crimped onto said lead between said first and second main body portions to make electrical connection between said leads and their associated metal eyelets.

Claim 14

A liquid level sensor for sensing the level of liquid in a container comprising, a holder composed of electrically insulating material and adapted for mounting in a wall of the container, said holder comprising first and second main body portions with connecting struts therebetween, two long metal eyelets extending from said first main body portion to said second main body portion, an encapsulated sensing element fixed to the side of said first main body portion that is remote from said second main body portion, protective means protruding from said side of the holder to provide mechanical protection for said encapsulated sensing element, and two electrical leads protruding from the encapsulation of the sensing element and electrically connected to said sensing element, each of said leads extending into an associated one of said metal eyelets at said side of said first main body portion with said associated metal eyelet being crimped onto said lead between said first and second main body portions to make electrical connection between said leads and their associated metal eyelets.

Claim 15

A liquid level sensor as claimed in claim 11 wherein said eyelets protrude from the side of said second main body portion remote from the first body portion to form electric terminals for the sensor.

Claim 16

A probe for monitoring a liquid comprising, a sealed metal can, a thermally sensitive semiconductor element housed within said can with one face thereof mounted on an inner face of a metal end wall of the can so as to be in electric and thermal contact with said metal end wall thereby to form a current path in the semiconductor body between the metal end wall and the opposite face of the semiconductor element, said metal end wall permitting heat exchange between the semiconductor element and a liquid contacting the can, a seal in the opposite end of the can for sealing the can against its environment, first and second electric leads protruding externally from the opposite end of the can via said seal, and means electrically connecting said first and second leads to the can wall and to said opposite face of the semiconductor element, respectively, for passing a current through said semiconductor element.

Claim 17

A probe for monitoring a liquid comprising, a sealed metal can, a thermally sensitive semiconductor element housed within said can with one face thereof mounted on an inner face of a metal end wall of the can so as to be in electric and thermal contact with said metal end wall thereby to form a current path in the semiconductor body between the metal end wall and the opposite face of the semiconductor element, said metal end wall permitting heat exchange between the semiconductor element and a liquid contacting the can, a seal in the opposite end of the can for sealing the can against its environment, first and second electric leads protruding externally from the opposite end of the can via said seal, and means electrically connecting said first and second leads to the can wall and to said opposite face of the semiconductor element, respectively, for passing a current through said semiconductor element.

Claim 18

A probe as claimed in claim 13 wherein the material of the can walls is chosen to have a relatively low thermal conductivity such that thermal conductance from the semiconductor element through the metal side wall of the can is insignificant relative to that through the metal end wall of the can.

Claim 19

A probe as claimed in claim 13 wherein the semiconductor element is mounted on a mass of good thermally and electrically conductive material which extends beyond the edge of the semiconductor element and is in thermal contact with the inner face of said metal end wall under and beyond the semiconductor element.

Claim 20

A probe as claimed in claim 13 wherein said electric connecting means includes a spring metal strip with one end contacting said opposite face of the semiconductor element and the other end secured to said second electric lead.

Claim 21

A probe as claimed in claim 13 further comprising an electric insulating material coating said first and second electric leads.

Claim 22

A liquid level sensor as claimed in claim 11 wherein said connecting struts include thin-walled portions surrounding the two metal eyelets between sAid first and second main body portions for insulating the metal eyelets.