US2392458A - Vacuum control check valve - Google Patents

Description

Jan. 8, 1946. c s 2,392,458 V VACUUM CONTROL CHECK VALVE Filed April 21, 1944 AIR F/L TER v INVENTOR. BERT G. CARLSON JZTTORNEX Patented Jan. 8, 1946 2,392,453, VACUUM CONTROL CHEGK VALVE Bert G. Carlson, Gates Mills, Ohio, assignor, by mesne assignments, to Jack & Heintz, Inc., Cleveland, Ohio, a corporation of Ohio Application April 21, 1944, Serial No. 532,050

2 Claims.

This invention relates to vacuum control devices and has for one of its primary objects the provision of a vacuum control unit for use in the vacuum system of an automatic pilot including the gyro box, suction pump and air filter which will effectively prevent excessive pressures being built up in the gyro box by the provision of a spring check valve between the air filter and the control unit leading to the gyro box to by-pass the same from the air filter line to the suction pump line and the provision of a floating check valve in the unit which will close upon the occurrence of backfire in the suction pump to prevent the ingress of air, oil or foreign matter from the suction pump into the control unit casing or into the gyro box.

With the foregoing and other objects in view theinvention resides in the combination of parts and in the details of construction set forth in the following specification and appended claims, certain embodiments thereof being illustrated in the accompanying drawing in which:

Figure l is a view in vertical section taken through the vacuum control anddiagrammatically showing the vacuum system including the automatic pilot gyro box, suction pump and air filter;

Figure 2 is a view in perspective of the spring check valve; and

Figure 31s an enlarged plan view of the floating check valve.

Referring more particularly to the drawing, the conventional automatic pilot gyro box is indicated at I. As is conventional practice in pneumatic-hydraulic automatic pilots the gyro box is evacuated by a suction pump 2 to spin the gyro wheel and create the air force necessary for the functioning of the pneumatic parts of,the automatic pilot operating system. Air from the outside is first drawn through an air filter 3 and through a pipe 4 into chamber 5 of the control unit casing 6 which chamber communicates through pipe I to the gyro box I to be evacuated. The outlet from the gyro box is through pipe 8 and intake opening 9 into a chamber in the control unit casing 6 and out through passage II and pipe l2 to the suction pump 2.

In the chamber l3 intermediate chamber In and the outlet passage to pipe I2 is a floating check valve [4 which abuts the screw plug by reason of suction in pipe I 2 leaving passage for air from chamber In through passage I6 and chamber l4 and through outlet II to pipe l2. If, however, a backfire or back pressure occurs in the suction pump the floating check valve I4 is forced to the left against the casing wall I! to close passage 1 6 to prevent air from rushing back into chamber It! or to the gyro box. Moreover, inasmuch as the motor for running the suction pump may utilize oil the closing by check valve I 4 of passage It prevents the ingress of any oil or foreign matter into the chamber [0 or the gyro box.

Provision is also made against an excessive amount of air being drawn by the suction pump through the air filter to the gyro box. This includes a spring check valve l8 normally maintained downwardly against its seat [9 to close a passage '20 between passage 5 and chamber 10 by a compression coil spring 2| which also bears against a plate 22 carrying a stem 23 screwthreaded in casing 6 so as to adjust the compression of spring 2|.

In the event that a predetermined undesirable amount of back pressure develops in chamber 5 the valve [8 becomes unseated against the action of spring 2 I. The air thus flowing into chamber I0 is caught in the suction flow of air and flows out through passages l6 and l I and pipe I2 to 25 the suction pump.

The two check valves l4 and I8 operate independently of each other and without interference to respectively prevent the sucking in of air, oil or foreign material into the gyro box upon backfiring of the suction pump motor and prevent the building up of excessive pressure in. air filter line being delivered to the gyro box.

I claim:

1. In combination in a vacuum system for evacuating and motivating the instrumentalities of an automatic pilot gyro box, including a suction pump and an air filter, a vacuum control unit between said air filter and gyro box and between said suction pump and gyro box, said control unit including. a casing having a central chamber having an inlet from the gyro box line and an outlet port to the suction pump line, a floating check valve permitting flow at all times to said suction pump line and operable upon occurrence of back pressure therein to close said outlet port to prevent transfer of back pressure into said central chamber or gyro box, said casing also having a passage communicating with the gyro box and air filter lines and a by-pass between said passage and said central chamber, a spring check valve in said central chamber for normally maintaining said passage closed and adapted to be opened upon the occurrence of excess pressure in said air filter line to by pass such pressure away from the gyro box line into said central chamber and into the suction fiow'of the suction pump line.

air filter and gyro box and between and in communication with said suction pump and gyro box, said control unitcomprising a casing having a.

sage communicating with the gyro box and air central chamber; a check valve permitting fiowj at all times to the suction pump line and operable in response to back pressure therein to close flow from said suction pump line to said central chaml 7/ p 7' her and gyro box, said casing also having a pas filter lines and a by-pass between said passage and said central chamber, a check valve in said central chamber and adjustable spring means for normally maintaining said passage closed and adapted upon the occurrence of excess pressure in said air filter line to by-pass such pressure away from the gyro box line and into said central chamber and into the suction flow of the suction pump line, said check valves being operable independently of each other without interference.

BERT G. CARLSON.

Images