US 4,792,192 A · Automatic brake source select system

Abstract

A brake source select system for selecting one of a plurality of sources of pressurized hydraulic fluid for use in actuating a brake system. The brake source select system (10) includes a primary, secondary and reserve source (20, 22 and 24) of pressurized hydraulic fluid connected in fluid communication respectively to a primary selector valve (32), a secondary selector valve (96) and a reserve selector valve (102). Pressurized hydraulic fluid from the primary source (20) is applied to deselect ports (94 and 100) on the secondary and reserve selector valves, causing those valves to block fluid flow from their associated sources to the brake system, so long as the primary source is operative. Upon failure of the primary source, pressurized fluid is no longer applied to the deselect port of the secondary selector valve, thereby enabling fluid flow through the valve, and causing pressurized hydraulic fluid from the secondary source to be applied to the deselect port (160) of the reserve selector valve and to a deselect port (164) of the primary selector valve, effectively blocking fluid flow through each of those valves. Should the secondary source fail, elimination of the pressurized fluid applied to the deselect port of the reserve selector valve enables it to conduct pressurized hydraulic fluid to the brake system, and applies the pressurized hydraulic fluid to the primary and secondary selector valve deselect ports, blocking fluid flow through those valves. Thus, failure of a higher priority source automatically results in selection of a next lower priority source to provide pressurized fluid to the brake system. In addition, a source of pressurized fluid associated with retraction of a landing gear is applied to a selection port (208) of the secondary selector valve, causing that valve to provide a source of pressurized hydraulic fluid to actuate the brakes, slowing the rotation of wheels prior to full retraction of the landing gear.

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Claims30

Dependent claims

A brake source select system, for selecting one of a plurality of separate sources to provide pressurized fluid to a brake system according to a preferred priority, so that if one or more sources having a higher priority fails, a source that is next in preferential priority is selected, comprising:

(a) a plurality of differential fluid pressure actuated valves, each valve having at least one inlet port, at least one outlet port, at least one select port through which a pressurized fluid may be applied to cause the valve to provide fluid communication between the inlet port and the outlet port and at least one deselect port through which a pressurized fluid may be applied to cause the valve to block fluid communication between the inlet port and the outlet port, one valve being associated with each of the sources of pressurized fluid;
(b) a plurality of source lines, each connecting one of the sources of pressurized fluid in fluid communication with the inlet port of the valve associated with that source;
(c) a plurality of supply lines, each connecting the outlet port of one of the valves in fluid communication with the brake system;
(d) a plurality of activation lines, each connecting one of the sources in fluid communication with one of said select ports of the valve associated with said one source;
and
(e) a plurality of deactivation lines, each connecting one of the sources having a higher priority in fluid communication with one of said deselect ports of the valves associated with sources having a lower priority, pressurized fluid provided by said higher priority sources causing each of the valves associated with the sources of lower priority to block fluid flow between their inlet port and outlet port, loss of fluid pressure due to failure of one or more sources of higher priority resulting in the source of next lower priority that has not failed being selected to provide pressurized fluid to the brake system.

3 more elements

For use in a brake system having redundant sources of pressurized fluid, a brake source select system for automatically connecting one of the sources in fluid communication with the brake system according to a predefined sequence upon failure of all sources prior in the sequence, said brake source select system comprising:

(a) selector valve means for connecting a pressure line from a selected source and a return line to said selected source in fluid communication with the brake system, and for blocking fluid communication between pressure lines from all nonselected sources and the brake system and between return lines to said nonselected sources and the brake system, in response to a differential fluid pressure and a biasing force applied to the selector valve means;
(b) biasing means associated with the selector valve means, for providing the biasing force, said biasing force being operative to bias the selector valve means to block fluid communication between the sources of fluid pressure and the brake system;
(c) deselect means for providing a fluid pressure to the selector valve means from a first operative source of fluid pressure in the preferred sequence, said deselect pressure in combination with said bias force causing the selector valve means to block fluid communication between all other sources of fluid pressure of lower priority in the sequence and the brake system;
and
(d) select means for providing a fluid pressure to the selector valve means to counter the force provided by the biasing means, said fluid pressure causing said selector valve means to enable fluid communication between the first operative source of fluid pressure in the preferred sequence and the brake system, so that upon failure of one source of pressure, the next source of pressure in the preferred sequence is connected to the brake system.

2 more elements

For use with a braking system of an aircraft having at least a first and a second source of pressurized hydraulic fluid for use in actuating the aircraft's brakes, a brake source selection system operative to select the first source, and if it has failed, to select the second source, said brake source selection system comprising:

(a) a first selector valve associated with the first pressure source, including a pressure inlet port, a pressure outlet port and a return outlet port, at least one deselect control port, at least one select control port, and a movable insert that in one position provides fluid communication between the pressure inlet and outlet ports, and in another position, provides fluid communication between the pressure outlet port and the return outlet port while blocking fluid flow through the pressure inlet port, the position of the movable insert depending upon application of a fluid pressure to one of the select and deselect control ports;
(b) a second selector valve associated with the second pressure source, including a pressure inlet port, a pressure outlet port, a return inlet port, a return outlet port, at least one deselect control port, at least one select control port, and a movable insert that in one position provides fluid communication respectively between the pressure inlet and outlet ports, and the return inlet and outlet ports, and in another position blocks such fluid communication, the position of the movable insert depending upon application of a fluid pressure to the select and deselect control ports;
(c) a first and a second pressure line respectively connecting the pressure inlet port of the first selector valve in fluid communication with the first source and the pressure inlet port of the second selector valve in fluid communication with the second source;
(d) a first and a second supply line respectively connecting the pressure outlet port of the first and second selector valves in fluid communication with the braking system;
(e) a first and a second select line respectively connecting the first pressure line in fluid communication with the select control port of the first selector valve and the second pressure line in fluid communication with the select control port of the second selector valve;
(f) a deselect line respectively connecting the first pressure line in fluid communication with the deselect control port of the second selector valve and the second supply line in fluid communication with the deselect control port of the first selector valve;
and
(g) spring means for biasing the movable insert of the second selector valve toward the position blocking fluid communication between its pressure inlet port and outlet port and between its return inlet port and outlet port in combination with fluid pressure applied to the deselect control port of the second selector valve from the first pressure line, said first source being normally connected in fluid communication with the brake system;
failure of the first source interrupting application of fluid pressure to the deselect control port of the second selector valve, permitting the fluid pressure from the second source applied to the select control port of the second selector valve to overcome the spring means, forcing the movable insert within the second selector valve to the position enabling fluid communication between the second source and the brake system and applying fluid pressure to the deselect control port of the first selector valve, thus forcing the movable insert within the first selector valve to the position blocking fluid communication between the first pressure line and the brake system.

6 more elements

Dependencies are inferred from the claim text.

Description5,979 words

Summary1,399 words

#This invention generally relates to a brake system, and more specifically, to a system for selecting a source of pressurized brake fluid from a plurality of such sources.

#One of the more important systems on any vehicle is its braking system. Clearly, failure of the braking system on a vehicle creates a high probability of an accident causing substantiel property damage and injury. Accordingly, modern automobiles are typically provided with redundant braking systems to ensure that at least partial braking capacity remains should the primary system fail.

#A reliable brake system is even more critical on an aircraft, particularly large commercial jet aircraft carrying hundreds of passengers and landing at speeds of several hundred miles per hour. Failure of the brake system on an aircraft may cause the plane to overshoot the end of the runway, or to collide with other taxining aircraft or ground structures, resulting in damage and possible loss of life. Thus, it is important that the braking systems installed on aircraft be designed to greatly reduce the likelihood of even a partial brake failure. Unlike either the manual or power assisted brakes of an automobile, large aircraft brakes are actuated by pressurized fluid provided by a hydraulic pump in response to brake pedal force. The brake pedal controls a metering valve to modulate the pressure applied to the brakes. A fully redundant braking system on an aircraft includes both multiple sources of pressurized fluid and multiple metering valves to ensure that full braking capacity is always available.

Brief description of the drawings3 figures

#FIG. 1 is a schematic diagram showing the brake source selector system;

#FIG. 2 is a plan view of one of the selector valves used in the brake source selector system; and

#FIG. 3 is a cross-sectional view of selector valve, taken along section line 3--3 of FIG. 2.

Detailed description4,531 words

#FIG. 1 schematically illustrates in a block diagram the configuration of a preferred embodiment of the brake source selector system, generally denoted by reference numeral 10. Brake source select system 10 is used to automatically select one of a plurality of sources of pressurized hydraulic fluid for use in actuating the brakes associated with the wheels of an aircraft on which the source selector system is installed. In the referenced figure, only two wheels 12 and 14 are shown, exemplary of the plurality of wheels on the landing gear of a large aircraft. Wheels 12 and 14 respectively include carbon brakes 16 and 18 of generally conventional design. Three separate hydraulic pumps (not shown) provide multiple redundant sources of pressurized hydraulic fluid for actuating carbon brakes 16 and 18 when the aircraft is landing, and while taxiing on the ground. Pressurized hydraulic fluid is applied to the brakes from one of the three sources according to a predetermined priority. The primary source 20 is normally selected as the source of pressurized fluid; however, should it fail, brake source selector system 10 automatically selects a secondary source 22, and if that source also fails, a reserve source 24.

#Pressurized hydraulic fluid from primary source 20 flows through a line 26 to a checkvalve 28, which is oriented to block fluid flow in the opposite direction, but to permit fluid flow from primary source 20 into a line 30, downstream of checkvalve 28. Line 30 is connected to a primary selector valve 32, at an inlet port 34. The hydraulic fluid flows through primary selector valve 32 and out an outlet port 36 into lines 38 and 44, which are in fluid communication with "normal" metering valves 40 and 42, respectively. Whenever the pilot or other member of the flight crew depresses the brake pedal in the cockpit (not shown) normal metering valves 40 and 42 respond by modulating the pressure of hydraulic fluid in lines 46 and 54, and thus the pressure applied to "normal" anti-skid valves 48 and 56, respectively. The modulated pressure of the hydraulic fluid applied to brakes 16 and 18 is also controlled by normal anti-skid valves 48 and 56. The anti-skid valves help to avoid wheel lockup and improve directional stability of the aircraft while braking on slippery surfaces. Hydraulic fluid at the modulated pressure developed by the normal metering and anti-skid valves is applied through a "T" connector 50 from normal anti-skid valve 48, to a line 52, which is in fluid communication with carbon brake 16. Similarly, brake fluid from normal anti-skid valve 56 is applied through a "T" connector 58 to a line 60, which is connected in fluid communication with carbon brakes 18.

#Should primary selector valve 32 fail, an alternative path for pressurized hydraulic fluid from primary source 20 is provided through a line 62, which is connected in fluid communication with line 26. The pressurized hydraulic fluid from primary source 20 thus flows through lines 26 and 62, and through a checkvalve 64, oriented to permit fluid flow from primary source 20 into an attached line 66, disposed downstream from checkvalve 64. Fluid flow is blocked from line 66 back toward line 62 by checkvalve 64. The other end of line 66 is connected in fluid communication with lines 38 and 44, providing an alternate path for pressurized hydraulic fluid from the primary source to flow to normal metering valves 40 and 42.

Automatic brake source select system

Life of this patent

Automatic brake source select system

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims30

Description5,979 words

Drawings

Classification8 codes

Life of this patent

Description5,979 words