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US 5,704,455 AGranted
Automatic brake booster
AssigneeJidosha Kiki Co., Ltd.
InventorMakoto Watanabe
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AssigneeJidosha Kiki Co., Ltd.
InventorMakoto Watanabe
Estimating the term…
An automatic brake booster having the functioning of an automatic brake, or more specifically, an improvement of bellows contained in a shell thereof is disclosed. The bellows comprises a stepped tubular member having portions of different diameters, namely, a reduced diameter, a medium diameter and an increased diameter. By using a reinforcing ring having a rigidity in the step, an expansion to increase the diameter of the bellows when the atmosphere is introduced into the internal space of the bellows can be prevented. Different diameters of the portions of the bellows allows the likelihood to be minimized that an output loss of the brake booster may be caused by contact of bellows portions to each other as the bellows is axially shrunk. As compared with an accordion-like bellows, the stepped tubular bellows can utilize a simplified die assembly and manufacturing steps and thus can be manufactured inexpensively.
An automatic brake booster including a valve body slidably disposed in a shell, a power piston mounted on the valve body, a constant and a variable pressure chamber defined across the power piston, a tubular bellows disposed within the constant pressure chamber, and a valve mechanism received within the valve body for switching a fluid circuit between a constant pressure passage communicating with the internal space of the bellows and a variable pressure passage communicating to the variable pressure chamber, thus allowing either a negative pressure or the atmosphere to be selectively supplied to the internal space of the bellows, wherein the bellows comprises a stepped tubular member having a small diameter portion, a middle diameter portion and a large diameter portion, these portions being formed in the mentioned order, and a reinforcing ring being disposed in at least one radial step of the stepped tubular member.
Dependencies are inferred from the claim text.