Fluid-pressure and analogous brake systems – Multiple control
Patent
1982-08-31
1984-04-24
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Multiple control
303 10, 303117, B60T 802
Patent
active
044444389
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention pertains to a power and manual vehicle hydraulic brake system and equivalent remote control.
BACKGROUND ART
U.S. Pat. No. 4,121,874 discloses a power and manual hydraulic brake system for an airplane, along with anti-skid control for the same. A relay valve and a shuttle valve coact with the pilot's manual master-cylinder to effect control of the power-assisted mode brake cylinder.
However, there is no isolation valve, as there is in the present invention. When the system of the patent is in the manual mode the passageway that connects from the manual master-cylinder to the power brake cylinder remains a part of the hydraulic system. Thus, actuation of the pilot's master-cylinder displaces fluid through that passageway and into the power brake cylinder to operate it, even though the power system is inoperative and no further functioning in that system takes place.
This displacement of fluid reduces the maximum hydraulic pressure obtainable during manual operation by about 25% to 33% in most installations of what it would be if the same system were wholly manual.
This is a very serious reduction of performance capability in the manual mode.
DISCLOSURE OF INVENTION
A power and manual mode wheel brake system, typically provided in duplicate for airplanes, to allow independent braking of the right and the left main landing wheels. A novel isolation valve is provided within each system, which valve fully hydraulically isolates the manual part of the system from the power part of the system when only the manual part is in operation.
Previously, the plumbing associated with the power brake cylinder has not been isolated from the manual system. The power brake cylinder has therefore been actuated, although without effect, causing a significant loss of displacement and pressure for the manual operation of the brakes. This loss has invariably resulted in sub-marginal braking performance in the manual mode.
The novel isolation valve, common to both the power and manual braking systems, retains full manual braking performance.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic representation of the dual power and manual mode brake system, shown in the power mode.
FIG. 2 is the same, but shown in the manual mode.
FIG. 3 is a cross-section of the isolation valve and the companion power brake valve for operating one side of the left and right brake system of FIGS. 1 and 2.
BEST MODE FOR CARRYING OUT THE INVENTION
In FIG. 1 the large rectangle identified by numeral 1 represents the valve control portion of a dual mode control system, typically duplicated for right and left wheels of an airplane, and shown in the power operating mode.
Elongated vertical element 2 is the right wheel isolation valve. It is detailed in the upper half of FIG. 3. Piston 3 extends nearly the entire length of the valve. In FIG. 1 it is shown in the upper, power mode, position.
Tubing 4 connects to the isolation valve at port 5 and elsewhere to the right master-cylinder of the manual mode part of the system. The master-cylinder is operated directly by the pilot of the airplane by depressing the right brake pedal with his foot. This structure is conventional and so has not been shown.
In FIG. 1, tubing carrying master-cylinder hydraulic pressure is identified by a black legend. Tubing carrying power brake pressure, to operate wheel brake cylinders in the power mode, is identified by cross-hatching. Tubing carrying system hydraulic pressure, provided by a power-driven pump, is identified by oblique stripes. Tubing carrying return hydraulic fluid to a reservoir is identified by the absence of any legend within the tubing.
Piston 3 is retained in the upward position shown by pressure exerted on the lower end thereof by system pressure in volume 6, which enters at tubing inlet 7 from the power-driven pump. This system pressure is typically within the range of 70 to 210 kilograms per square centimeter, (kg/cm.sup.2), or 1,000 to 3,000 pounds per square inch (p.s.i.).
The power-driven pump may be of the gear o
REFERENCES:
patent: 3503655 (1970-03-01), Heimler
patent: 3661427 (1972-05-01), Hodge
patent: 4121874 (1978-10-01), Knox et al.
patent: 4251115 (1981-02-01), Knox et al.
Butler Douglas C.
Lubcke Harry R.
Tempco Engineering, Inc.
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