US 6,035,881 A · Checkvalve unit

Abstract

A checkvalve (1) is provided with an inlet which can be connected to an operating system requiring a negative pressure, e.g. to a braking force amplifier (17), an outlet (3) which can be connected to a negative-pressure system producing a negative pressure, a main air channel (4) connecting the inlet and the outlet in a fluid manner and enabling an air flow in the direction of the outlet, a first checkvalve (9) installed in the main air channel (4), a single outside-air channel (5) which branches off downstream of the first checkvalve (9) and lets out into the atmosphere and a cross-sectional narrowing (7) in the manner of a venturi pipe (6), a venturi channel (8) connecting the cross-sectional narrowing (7) upstream of the first checkvalve (9) to the main air channel (4) and a second valve (10) located between the inlet (2) and the cross-sectional narrowing (7) in the main air channel (4) or in the venturi channel (8). A shut-off valve is located before or after the cross-sectional narrowing (7) in the outside-air channel (5) and is actuated as a function of the system pressure (p.sub.S) prevailing in the operating system in such a manner that the connection to the atmosphere is established when a predetermined target pressure (p.sub.Soll) is exceeded and is interrupted when the pressure drops below this pressure.

Claims14

Dependent claims

A check valve apparatus for maintaining negative pressure in an operating system, said check valve comprising:

an inlet connectable to an operating system requiring a negative pressure, and an outlet connectable to a system producing a negative pressure;
a main air channel establishing an air flow path between said inlet and said outlet;
a first check valve disposed in said main air channel;
an outside air channel having one end in communication with said main air channel at a location downstream of said first check valve in a direction of air flow through said main air channel to said outlet, said outside air channel in communication with atmospheric pressure at an opposite end thereof;
a cross-sectional narrowing defined in said outside air channel with a venturi channel disposed between said cross-sectional narrowing and said main air channel;
a second check valve disposed in communication between said main air channel and said cross-sectional narrowing;
and
an automatically actuating shut off valve disposed in said outside air channel to alternately isolate and open said outside air channel to atmospheric pressure as a function of a pressure difference between operating system pressure and atmospheric pressure.

5 more elements

Dependencies are inferred from the claim text.

Checkvalve unit

Life of this patent

Checkvalve unit

Life of this patent

Abstract

Claims14