Device for measuring liquid level and air pump for use therein

Claim 2

In a device for measuring the level of a liquid in a container, said device comprising a manometric measuring tube, a pneumatic circuit connected both to said tube and to said container beneath the level of liquid therein, and a flexible membrane mounted to force a gas into said circuit between said tube and container, the improvement which comprises a constant volume chamber connected both to said circuit and to atmosphere through separate orifices, a variable volume chamber the volume of which is dependent on the position of said membrane and which is in constant commuNication with said constant volume chamber, and operating means for flexing said membrane to reduce the volume of said variable volume chamber and thereby force gas into said constant volume chamber thence into said circuit, while simultaneously closing the orifice connecting said constant volume chamber to atmosphere.

Claim 3

Device as claimed in claim 1 in which said operating means comprises a drive member which is movable between a position closing the orifice leading to atmosphere and one leaving that orifice open, a driving member connected to flex said membrane, and friction means through which said driven member is actuated by movement of said driving member.

Claim 4

Device as claimed in claim 2 in which said driven member is biassed away from the orifice leading to atmosphere by a resilient member and fits telescopically into said driving member, with said driven member, sliding in said driving member after it has reached the limits of its path of travel.

Claim 5

Device as claimed in claim 3 in which the membrane is a frusto-conical sleeve open at its two ends the periphery of the smaller end being sealingly attached to the operating member and the periphery of the other end being sealingly attached between the body of the pump and a wall separating said constant volume chamber from said variable volume chamber.

Claim 6

An air pump comprising a constant volume chamber having an air vent and a separate air outlet, and a variable volume chamber separated from said constant volume chamber by a common wall defining an orifice connecting said chambers, a flexible diaphragm mounted to control the volume of said variable volume chamber, an operating member connected to move said diaphragm between a first position at which the volume of said variable volume chamber is at its maximum and a second position in which said volume is at its minimum, and a valve member frictionally driven by said operating member to close said air vent as operating member begins to move said diaphragm toward said second position.

Claim 7

An air pump comprising a constant volume chamber having an air vent and a separate air outlet, and a variable volume chamber separated from said constant volume chamber by a common wall defining an orifice connecting said chambers, a flexible diaphragm mounted to control the volume of said variable volume chamber, an operating member connected to move said diaphragm between a first position at which the volume of said variable volume chamber is at its maximum and a second position in which said volume is at its minimum, and a valve member frictionally driven by said operating member to close said air vent as operating member begins to move said diaphragm toward said second position.

Claim 8

An air pump as claimed in claim 6 in which said valve member is carried by a rod which passes through said wall and one end of said rod is telescopically received within said operating member.

Claim 9

An air pump as claimed in claim 6 in which said one end of said rod is divided into two prongs by an axial slit and resilient means within said slit biasses said prongs outwardly against said operating member to provide said friction drive.

Claim 10

In combination, an air pump as claimed in claim 5 and a device for measuring the level of a liquid in a container, said device comprising a manometric measuring tube, and a pneumatic circuit connected both to said tube and to said container beneath the level of the liquid in said container, said air outlet being connected to said circuit between said tube and container.

Claim 11

In a device for measuring the level of a liquid in a container located in a vehicle, said device comprising a manometric measuring tube, a pneumatic circuit connected to both said tube and to said container beneath the level of liquid therein, and a flexible membrane mounted to force a gas into said circuit between said tube and container, the improvement according to which the median plane of the manometric tube is parallel to the direction of movement of the vehicle, said tube comprises a generally horizontal lower middle portion containing a throttle, a first upper end portion positioned to be seen by the driver of the vehicle, and a second upper end portion which is S-curved and then connected to the pneumatic circuit, and said device further comprises a constant volume chamber connected both to said circuit and to atmosphere through separate orifices, a variable volume chamber the volume of which is dependent on the position of said membrane and which is in constant communication with said constant volume chamber, and operating means for flexing said membrane to reduce the volume of said variable volume chamber and thereby force gas into said constant volume chamber and thence into said circuit, while simultaneously closing the orifice connecting said constant volume chamber to atmosphere.

Claim 12

In a device for measuring the level of a liquid in a container located in a vehicle, said device comprising a manometric measuring tube, a pneumatic circuit connected to both said tube and to said container beneath the level of liquid therein, and a flexible membrane mounted to force a gas into said circuit between said tube and container, the improvement according to which the median plane of the manometric tube is parallel to the direction of movement of the vehicle, said tube comprises a generally horizontal lower middle portion containing a throttle, a first upper end portion positioned to be seen by the driver of the vehicle, and a second upper end portion which is S-curved and then connected to the pneumatic circuit, and said device further comprises a constant volume chamber connected both to said circuit and to atmosphere through separate orifices, a variable volume chamber the volume of which is dependent on the position of said membrane and which is in constant communication with said constant volume chamber, and operating means for flexing said membrane to reduce the volume of said variable volume chamber and thereby force gas into said constant volume chamber and thence into said circuit, while simultaneously closing the orifice connecting said constant volume chamber to atmosphere.