Patent ID: 8166865

Claim:
A brake booster with a variable boost ratio comprising: a pneumatic control device ( 10 , 14 , 15 ) controlled by a three-way valve, a slide valve plunger ( 21 ) providing control of the pneumatic control device, a control rod ( 20 ) intended to apply an axial movement force to the slide valve plunger, a piston ( 22 ) able to move axially under the control of the pneumatic control device, a push rod ( 30 ) receiving axial movement forces from said moving piston and from the slide valve plunger ( 21 ) and forwarding the forces to a brake master cylinder, a reaction disk ( 23 ) positioned between the control rod ( 20 ) and the push rod ( 30 ), and a sensor feeler device ( 4 ) able to move axially and situated between the reaction disk ( 23 ) and the control rod ( 20 ), the sensor feeler device ( 4 ) comprising: an axially moveable cylinder ( 40 ) the movement of which can be controlled by the control rod, a rear part ( 41 ) separate from the axially moveable cylinder ( 40 ) and one of welded and bonded to the axially moveable cylinder ( 40 ), a sensor feeler piston ( 5 ) able to move axially in the axially moveable cylinder ( 40 ), a spring ( 44 ) that tends to push the sensor feeler piston ( 5 ) forward and keep its front face substantially in the same plane as a front face of the axially moveable cylinder.