To secure rigidity which can satisfy a further strict durability requirement at an external peripheral part of a booster piston, in a negative pressure booster in which a diaphragm is joined to a rear face of the booster piston which integrally has a center cylinder part forming a center hole, a ring-plate shaped center hole edge part hanging out to the outside in a radial direction from one end part of the center cylinder part, an umbrella-shaped part continuing to an external periphery of the center hole edge part, and an external peripheral part spreading to the outside of the radial direction from the umbrella-shaped part.SOLUTION: An external peripheral part 74 has at least: a first external peripheral tapered portion 74a; a second external peripheral tapered portion 74b extending toward a negative pressure chamber side while making a small-diameter end continue to an external periphery of the first external peripheral tapered portion 74a; and a third external peripheral tapered portion 74c extending toward the negative pressure chamber side by enlarging an inclination angle α2 with respect to a virtual plane PL2 orthogonal to an axial line of a booster piston 18 larger than an inclination angle α1 of the second external peripheral tapered portion 74b while making a small-diameter end continue to an external periphery of the second external peripheral tapered portion 74b.SELECTED DRAWING: Figure 3
【課題】中心孔を形成する中心筒部と、中心筒部の一端部から半径方向外方に張り出すリング板状の中心孔縁部と、この中心孔縁部の外周に連なる傘状部と、傘状部から半径方向外側に広がる外周部とを一体に有するブースタピストンの後面にダイヤフラムが結着される負圧ブースタにおいて、ブースタピストンの外周部でより厳しい耐久要件を満たすことができる強度を確保する。【解決手段】外周部74が、第1の外周テーパ部分74aと、当該第1の外周テーパ部分74aの外周に小径端を連ならせて負圧室側に向かって延びる第2の外周テーパ部分74bと、第2の外周テーパ部分74bの外周に小径端を連ならせつつブースタピストン18の軸線に直交する仮想平面PL2に対する傾斜角α2を第2の外周テーパ部分74bの傾斜角α1よりも大きくして負圧室側に向かって延びる第3の外周テーパ部分74cとを少なくとも有する。【選択図】 図3
NEGATIVE PRESSURE BOOSTER
負圧ブースタ
2021-09-27
Patent
Electronic Resource
Japanese
IPC: | B60T Bremsanlagen für Fahrzeuge oder Teile davon , VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF |