Variable inductance transducers

A variable inductance linear transducer comprising a housing carrying an axially movable plunger with a projecting tip for engaging a body, the movement of which is to be measured, a magnetic core in said plunger and a coil assembly within said housing and enclosing said plunger, wherein the external surface of said plunger is of ceramic material, and further comprising a bearing sleeve of ceramic material within said housing, and said plunger being guided for linear movement solely by being in direct sliding contact in said bearing sleeve, and wherein the body of said plunger is a plain hollow cylinder of ceramic material, substantially free of flanges, and said body contains an internal sleeve of non-ceramic material in which said core is mounted.

A variable inductance linear transducer comprising a housing carrying an axially movable plunger with a projecting tip for engaging a body, the movement of which is to be measured, a magnetic core in said plunger and a coil assembly within said housing and enclosing said plunger, wherein the external surface of said plunger is of ceramic material, and further comprising a bearing sleeve of ceramic material within said housing, wherein said plunger has first slide guiding means extending over a guide region of its longitudinal length, and said bearing sleeve has second slide guiding means extending over a guide region of its longitudinal length, said first and second slide guiding means being in direct sliding contact with each other and said plunger being guided for linear movement solely by said direct sliding contact between said first and second slide guiding means, and wherein said core is disposed in said plunger at a longitudinal position of said plunger at which said first and second slide guiding means co-operate.

A variable inductance linear transducer comprising a housing carrying an axially movable plunger with a projecting tip for engaging a body, the movement of which is to be measured, a magnetic core substantially wholly within said plunger and a coil assembly within said housing and enclosing said plunger, wherein the external surface of said plunger is of ceramic material, and further comprising a bearing sleeve of ceramic material within said housing, and said plunger being guided for linear movement solely by being in direct sliding contact in said bearing sleeve.

A variable inductance linear transducer comprising a housing carrying an axially movable plunger with a projecting tip for engaging a body, the movement of which is to be measured, a magnetic core provided inside said plunger and a coil assembly within said housing and enclosing said plunger, wherein the external surface of said plunger is of ceramic material, and further comprising a bearing sleeve of ceramic material within said housing, and said plunger being guided for linear movement solely by being in direct sliding contact in said bearing sleeve, said plunger and said bearing sleeve having complementary smooth parallel sides which co-operate with each other to guide sliding movement therebetween.

A variable inductance linear transducer comprising a housing carrying an axially movable plunger with a projecting tip for engaging a body, the movement of which is to be measured, a magnetic core inside said plunger and a coil assembly within said housing and enclosing said plunger, wherein the external surface of said plunger is of ceramic material, and further comprising a bearing sleeve of ceramic material within said housing, and said plunger being guided for linear movement solely by being in direct sliding contact in said bearing sleeve, and wherein said plunger defines a hollow cavity in which said core is adjustably mounted, said plunger having an access aperture at one end whereby access to said cavity is afforded to enable the position of said core relative to the longitudinal length of said plunger to be adjusted.