In this negative-pressure booster, one of a negative-pressure valve seat and a negative-pressure valve section has, provided thereto, one or more first protruding sections abutting against the other of the negative-pressure valve seat and negative-pressure valve section, at a site other than a first annular abutment site, in an initial state where an operational force has not been applied to an input member; and/or one of an atmospheric valve seat and an atmospheric valve section has, provided thereto, one or more second protruding sections abutting against the other of the atmospheric valve seat and atmospheric valve section, at a site other than a second annular abutment site, in the initial state where an operational force has not been applied to the input member.

In this negative-pressure booster, one of a negative-pressure valve seat and a negative-pressure valve section has, provided thereto, one or more first protruding sections abutting against the other of the negative-pressure valve seat and negative-pressure valve section, at a site other than a first annular abutment site, in an initial state where an operational force has not been applied to an input member; and/or one of an atmospheric valve seat and an atmospheric valve section has, provided thereto, one or more second protruding sections abutting against the other of the atmospheric valve seat and atmospheric valve section, at a site other than a second annular abutment site, in the initial state where an operational force has not been applied to the input member.

A check valve of this negative pressure-type booster device is provided with: a cylindrical section that is integrally formed with a shell disposed on one side, communicates with a connection pipe, and is formed in a cylindrical shape protruding toward the inside of a housing; and a valve body section that is disposed inside the cylindrical section, and is axially fitted, within the cylindrical section, to the cylindrical section such that air is permitted to flow from a negative pressure chamber to the connection pipe while the air is prohibited from flowing from the connection pipe to the negative pressure chamber.

A check valve of this negative pressure-type booster device is provided with: a cylindrical section that is integrally formed with a shell disposed on one side, communicates with a connection pipe, and is formed in a cylindrical shape protruding toward the inside of a housing; and a valve body section that is disposed inside the cylindrical section, and is axially fitted, within the cylindrical section, to the cylindrical section such that air is permitted to flow from a negative pressure chamber to the connection pipe while the air is prohibited from flowing from the connection pipe to the negative pressure chamber.

A pneumatic brake booster having a vacuum chamber and a working chamber in a booster housing separated from one another by an elastic diaphragm. The diaphragm bears in regions against a diaphragm plate axially displaceable between a zero position and a maximum stroke. An axial spacing between the zero position and the maximum stroke defines a stroke range of the brake booster. The diaphragm has a rolling fold which, during the displacement of the diaphragm plate, rolls on a rolling region on an inner wall of the booster housing. In order to offer a solution in which it is the intention for a modular system for different stroke ranges to be formed more efficiently and for the efficiency loss to be minimized or avoided, the booster housing has, in the rolling region, a tapered, conical portion with a cone angle 8 and an axial extent >*stroke range.

A pneumatic brake booster having a vacuum chamber and a working chamber in a booster housing separated from one another by an elastic diaphragm. The diaphragm bears in regions against a diaphragm plate axially displaceable between a zero position and a maximum stroke. An axial spacing between the zero position and the maximum stroke defines a stroke range of the brake booster. The diaphragm has a rolling fold which, during the displacement of the diaphragm plate, rolls on a rolling region on an inner wall of the booster housing. In order to offer a solution in which it is the intention for a modular system for different stroke ranges to be formed more efficiently and for the efficiency loss to be minimized or avoided, the booster housing has, in the rolling region, a tapered, conical portion with a cone angle 8 and an axial extent >*stroke range.

A pressure sensor for a brake booster includes a housing that receives a pressure sensor element and which has a first fluid connection, via which the pressure sensor can be connected to the brake booster. The housing has a second fluid connection with a receiving opening which at least partly receives a flow valve and a connection socket for a vacuum pump, wherein the flow valve releases the flow of fluid in the direction of the vacuum pump and blocks the flow of fluid in the opposite direction. The flow valve is designed as a membrane insert and is inserted into the receiving opening.

A pressure sensor for a brake booster includes a housing that receives a pressure sensor element and which has a first fluid connection, via which the pressure sensor can be connected to the brake booster. The housing has a second fluid connection with a receiving opening which at least partly receives a flow valve and a connection socket for a vacuum pump, wherein the flow valve releases the flow of fluid in the direction of the vacuum pump and blocks the flow of fluid in the opposite direction. The flow valve is designed as a membrane insert and is inserted into the receiving opening.

A two-position gate valve has a gate defining a full-flow passageway therethrough and defining a restricted-flow passageway therethrough, without defining a closed position. The full-flow passageway has an entrance with a first area and an exit with a second area, the second area being smaller than the first area, and the full-flow passageway continuously tapers from the entrance to the exit thereof. The restricted-flow passageway has an entrance with a third area and has an exit with a fourth area, the fourth area being smaller than the first area, the second area, and the third area, and the restricted-flow passageway continuously tapers from the entrance to the exit thereof. Flow through the full-flow passageway is in a first direction and flow through the restricted-flow passageway is also in the first direction and the ratio of the fourth area to the second area is in a range of 5 to 15.

A valve mechanism of this negative pressure type booster device has: a negative pressure valve seat provided on a valve body; an atmospheric valve seat provided on a plunger; and a valve part provided with a negative pressure valve section constituting a negative pressure valve together with the negative pressure valve seat and an atmospheric valve section constituting an atmospheric valve together with the atmospheric valve seat. The valve mechanism is provided with a tilting part which is provided on at least one of the valve body and the valve part and tilts the atmospheric valve section relative to a first plane formed when the negative pressure valve section and the negative pressure valve seat are brought into contact with each other to put the negative pressure valve in a closed state.