Tokico, Ltd.

Kiyoshi Shirahata

Mitsuhiro Endo

Hiromi Ando

Atsuya Koshu

A brake booster includes a housing, a partition adapted to divide the interior of the housing into two chambers, and two diaphragms adapted to divide the two chambers into constant and variable pressure chambers. A control valve includes a valve body carried by the diaphragms, and a plunger slidably received in the valve body. The control valve is operatively connected to the variable pressure chambers to develop a pressure differential across the diaphragms to cause the diaphragms to move in response to actuation of an input rod. A reaction disk is disposed between an output rod and the valve body to transmit the reaction of movement of the output rod to the input rod. An adjusting mechanism is disposed between the plunger and the reaction disk and compressible so as to develop a greater degree of pressure differential when a force applied by the input rod exceeds a predetermined level. The reaction disk is caused to make contact with the contact disk and held out of contact with the spring and the plunger when the plunger is actuated.

Pressure differential operated brake booster

A booster apparatus of a vacuum type for a brake device has a housing including therein a chamber, a diaphragm for dividing the chamber of the housing into a constant pressure chamber and a variable pressure chamber, an input shaft including a distal end, an output shaft including a proximal end, a plunger which is engageable with the distal end of the input shaft for transmitting force from the input shaft to the output shaft, a reaction disk disposed between the plunger and the proximal end of the output shaft for transmitting reaction from the output shaft to the plunger, and a valve body mounted on the diaphragm. The valve body includes a hole for slidably receiving the plunger, a recess for fixedly receiving the reaction disk and the proximal end of the output shaft which recess is larger than the plunger hole in inner diameter, and an intermediate hole portion disposed between the plunger hole and the recess. The intermediate hole portion is smaller than the recess and is larger than the plunger hole in inner diameter.

Booster apparatus of vacuum type

A plunger moved with an input shaft is movably fitted in an axial bore of a valve body made of resin, and a valve mechanism selectively establishes and cuts off communication in a negative pressure passage and an atmosphere passage formed in the valve body according to the movement of the plunger. Also, a pair of radial holes formed to have a circular cross section are provided in the valve body by drilling work, and a plate type stop key formed in a fork shape having two claw branches is mounted by loosely inserting the branches in the radial holes. The stop key limits a movement range of the plunger. Also, a guide portion is formed on an outer circumference of the valve body to guide side surfaces of the stop key. The movement of the stop key is restricted by the guide portion and a step formed in the axial bore of the valve body. Therefore, a smooth operation of the pneumatic booster can be guaranteed.

Growing community of inventors

Yamanashi-ken, Japan

Kiyoshi Shirahata