Fluid handling – Systems – Flow path with serial valves and/or closures
Patent
1997-04-10
1999-02-02
Lee, Kevin
Fluid handling
Systems
Flow path with serial valves and/or closures
25112915, 3031192, 13759617, F16K 3106, B60T 836
Patent
active
058652132
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a controllable valve. Such used as an intake valve in hydraulic brake system for motor vehicles with ABS, ASR traction control or dynamic vehicle movement control. They are disposed upstream of a return pump in an intake line coming from a master cylinder. In their basic position, these valves are closed, and they can be opened in operation of the return pump, so that this pump can aspirate brake fluid from the master cylinder.
Difficulties can arise if the return pump has to aspirate brake fluid from the master cylinder itself when the brake pedal is not being depressed. This delays the pressure buildup and hence the actuation of the vehicle brakes. To keep the intake resistance low, an opening cross-sectional area of the valve, which is normally the bore diameter of a valve seat, is selected to be large.
However, this has the disadvantage that the requisite forces for opening the valve are high. The actuating forces for opening the valve gain significance especially if the intake valve is to be opened while the master cylinder is actuated. In that case, the brake fluid at an inlet to the valve is under pressure, and the valve must be opened against a high pressure difference. This requires a strong and hence large electromagnet.
ADVANTAGES OF THE INVENTION
The valve according to the invention has the advantage that initially a first valve stage with a small opening cross-sectional area is opened, for which purpose a small actuating force suffices. The opening of the first valve stage causes a pressure drop, or more precisely a reduction in the pressure gradient at the valve according to the invention, as a consequence of which a second valve stage is opened by a spring element and uncovers a large opening cross-sectional area. As long as the pressure difference after opening of the first valve stage is great enough that the second valve stage does not open against this pressure difference, the brake fluid throughput through the first valve stage of the valve of the invention suffices to supply adequate brake fluid to the return pump for a rapid pressure buildup.
The valve of the invention has the further advantage that only the first valve stage has to be actuated, and all the actuating force is available to it. The second valve stage functions automatically. The valve of the invention has a simple design and a compact structure. Because of the low actuating forces, a magnet that is usual for the magnet valves of hydraulic vehicle brake systems can be used; the outer dimensions of the valve of the invention may agree with those of valves used in hydraulic vehicle brake systems, so that installing the valve of the invention in a hydraulic vehicle brake system presents no problems.
A advantageous further features of and improvements to the invention are defined hereinafter.
The valve of the invention may be actuated mechanically, pneumatically, or hydraulically, for example. Preferably, the actuation is effected electromagnetically.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in further detail below in terms of exemplary embodiments shown in the drawing. Shown are:
FIG. 1, a valve of the invention in axial section; FIGS. 2, 3 and 4, illustrate details of modified embodiments of the valve according to the invention as shown in FIG. 1; and
FIG. 5, illustrates a hydraulic circuit diagram of a vehicle brake system according to the invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
The valve 10 according to the invention, shown in FIG. 1, has a cylindrical armature 12, in one face end of which a ball, as a first valve closing body 14, is mounted by caulking. A second valve closing body 16 is disposed coaxially to the armature 12 and has a conical first valve seat 18 for the first valve closing body 14. This second valve closing body 16 takes the form of a ball cap, remote from the armature 12, with a radial flange on a bottom side of the ball cap toward the armature 12. The radial flange is drilled axially through to form a mouth which is embo
REFERENCES:
patent: 4830332 (1989-05-01), Miura et al.
patent: 5203617 (1993-04-01), Wilde
patent: 5542755 (1996-08-01), Staib et al.
patent: 5649748 (1997-07-01), Oehler et al.
patent: 5735582 (1998-04-01), Eith et al.
Scheffel Martin
Schwarz Hans-Friedrich
Stokmaier Gerhard
Greigg Edwin E.
Greigg Ronald E.
Lee Kevin
Robert & Bosch GmbH
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