Aisin Seiki Kabushiki Kaisha

Toyota Jidosha Kogyo Kabushiki Kaisha

Toyota Jidosha Kabushiki Kaisha

Osamu Ogura

Masayoshi Katagiri

Takashi Fujii

Hajime Arai

Kenichi Sato

Satoru Maruyamano

Masami Sugihara

A vehicle brake booster apparatus includes a housing, a movable wall positioned within the interior of the housing to divide the interior into a constant pressure chamber and a variable pressure chamber, a power piston connected to the movable wall for moving in response to movement of the movable wall, an axially movable input rod extending outwardly from the power piston for connection to a brake pedal, and an axially movable valve plunger mounted within the power piston and operatively connected to the input rod. A control valve is positioned within the power piston for controlling communication of the variable pressure chamber with atmospheric air. The control valve includes an air control valve and a vacuum control valve, with the air control valve including an air control seal arranged between the valve plunger and a valve body portion of the control valve. The air control seal has a radially outwardly located peripheral portion which possesses an elasticity that is greater than the elasticity of a radially inwardly located portion of the air control seal to thereby provide an effective air-tight seal.

Brake booster apparatus for a vehicle

A clutch master cylinder comprises a master cylinder body provided thereon with a fluid reservoir tank and therein with an inlet port in communication with the reservoir tank and an outlet port for connection to a slave cylinder, a piston axially slidably disposed within the cylinder body and arranged to be moved inward by a push-rod, a valve seat arranged between the inlet and outlet ports within the cylinder body to permit fluid flow passing therethrough, a valve body associated with the piston to cooperate with the valve seat in response to inward movement of the piston, a fixed plug mounted on the cylinder body, and an adjusting plug disposed within the cylinder body to adjust an axial space between the valve seat and the valve body, the adjusting plug having an outer end portion adjustably threaded into the fixed plug and fastened in place by a lock nut threaded thereon and being provided at an intermediate portion thereof with an annular flange engageable with the inner end of the fixed plug to restrict outward movement of the adjusting plug.

Clutch master cylinder

A brake booster of the stroke-enlarging type which includes a power piston disposed in a casing for being actuated by a difference in pressure on opposite sides thereof. The brake booster includes a transmission device in the form of a ball and ball retainer which are biased by a spring while the ball is retained between a surface of the power piston and a control piston. The ball and ball retainer are limited in movement by a stopper coupled to the power piston. The ball and ball retainer forming the transmission device are advanced in response to the spring bias by the power piston and are operated such that when a brake clearance has been extinguished and a reactionary force from the output member becomes larger than the preload of the spring, the reactionary force blocks the advance of the ball and ball retainer so that the reaction force is partly transmitted to the control piston with a resultant reduction of the reactionary force transmitted to the power piston.

Brake booster

A brake booster of stroke-enlarging type which includes a casing, a power piston so disposed as to divide the interior of the casing into two chambers for being actuated by the difference of pressure in the two chambers, a control piston, containing therein a valve mechanism for controlling the difference of pressure in the two chambers and a transmission mechanism for transmitting an input of an input member to an output member, being coaxially fitted into a central bore of the power piston relatively movably thereto and a reaction lever, which is abutted at an output portion in the middle thereof by the output member, receiving output of the transmission mechanism and output of the power piston respectively as an input at a first input portion and a second input portion thereof located on either side of said output portion in the middle, whereby a greater stroke can be obtained at the output member than a stroke input at the input member. Between the control piston and the power piston a locking mechanism including a ball and a ball retainer is disposed. The ball retainer is for transmitting an output of the power piston to the reaction lever via the ball, through abutment on a first input portion of the reaction lever. After the ball has been locked between the power piston and the control piston a reactionary force which comes from the reaction lever back to the ball retainer is mostly transmitted from the ball to the control piston, not to the power piston. Therefore the power piston is not pushed back even after the peak of the assisting force given to the power piston by the pressure difference.

A brake booster of stroke-enlarging type which includes a power piston disposed in a casing for being actuated by a difference in pressure on opposite sides thereof, a control piston, having therein a control valve for controlling the difference in pressure, being coaxially fitted into a central bore of the power piston relatively movable thereto and a reaction lever, which is abutted at an output portion in the middle thereof by an output member, receiving the output force of the power piston and the output force of the transmission mechanism respectively as an input force at a first input portion and a second input portion thereof located on either side of said output portion, whereby a greater stroke can be obtained at the output member than a stroke applied at an input member.

A brake booster of stroke-enlarging type which includes a power piston moved in accordance with the difference of pressure on opposite sides thereof, a control piston having therein a control valve for controlling the pressure difference and slidably fitted in a central bore of the power piston, an anti-backdown transmission mechanism disposed between the two pistons, a reaction lever abutted at an output portion thereof on an output member and, at a pair of input portions located on opposite sides of the output portion, on the control piston and the anti-backdown transmission mechanism respectively, and a return spring backwardly biasing the power piston. The anti-backdown transmission mechanism transmits the output force of the power piston to the reaction lever and the reactionary force of the reaction lever to the power piston in an initial operation stage of the booster, and after an advancing of the power piston in relation to the control piston by a predetermined amount it transmits the reactionary force of the reaction lever not to the power piston but to the control piston. An abutting portion is disposed on the power piston for abutting on the front side of the anti-backdown transmission mechanism for retracting the same to the original position together with the power piston which is forcibly retracted by the return spring.

A brake booster of stroke-enlarging type wherein the brake feeling is improved. The brake booster includes a casing, a power piston disposed in said casing so as to divide the interior of the casing into two chambers for being actuated by the pressure difference in the two chambers, and a control piston having a built-in control valve for controlling the pressure difference due to the operation of an input member. The power piston is so disposed as to be relatively movable for a predetermined distance with respect to the control piston and able to be advanced at the initial stage of the braking operation relative to the control piston at a stroke, independently of the amount of advancement of the input member, for the predetermined distance in order to give an output member a larger output stroke than stroke input. At least on one of the mutual abutting surfaces abutting to each other for restricting the end position of the relative movement for the predetermined distance of the power piston to the control piston a shock-absorbing member of rubber material is fixed.

A brake booster of the stroke enlarging type wherein a power piston operated by the pressure difference existing on opposite sides thereof is moveable relative to a control piston provided with a control valve for controlling the difference of the pressure, and the power piston and the control piston are engageable to be immovable relative to each other by means of a locking member after the pressure difference has reached a predetermined value. The power piston is so constructed as to be able to advance a larger distance than the control piston, while the pressure difference is small, to move the output member by a larger amount in comparison to a small amount of advancement of the input member of the booster. The locking member is normally retained at the retracted position by means of a spring and is advanced, against the action of the spring, when the pressure difference on opposite sides of the power piston has reached the predetermined value, to engage the power piston with the control piston so they move together and prevent the output member from remaining stationary upon advancement of the input member caused by to a retraction of the power piston relative to the control piston.

Growing community of inventors

Nagoya, Japan

Osamu Ogura