US1748496A - Exhaust-pressure-control valve - Google Patents

Description

Feb. 25, 1930.

H. RCIJWNTREE 1,748,496

EXHAUST PRESSURE CONTROL VALVE 7 Filed 001;. 24, 1927 2 Sheets-Sheet l .272 WWZZZ mm?) .03am

351 attozmeqgmmw Feb. 25, 1930. H. ROWNTREE EXHAUST PRESSURE CONTROL VALVE Filed Oct. 24, 1927 2 Sheets-Sheet 2 Patented Feb. 25, 1930 UNITED STATES PATENT OFFICE HAROLD ROWNTREE, OF SGAR SDALE, NEW YORK, ASSIGNOR TO NATIONAL PNEU- MATIG COMPANY, OF NEW YORK, N. Y., A CORPORATION OF WEST VIRGINIA ExHAUST-PRESSURE-CONTROL VALVE Application -filed October 24, 1927. Serial No. 228,135.

again move after havingbeen stopped by an obstruction.

A further object of this invention is the provision of a device of this type which is adapted to control the speed of the engine to prevent the slamming of doors operated thereby.

A further object of this invention is the provision of an exhaust valve for fluid engine which is controlled by differential pistons under the control of the fluid from the fluid source and the fluid from the exhaust end of the engine.

This and many other objects are secured by means of the construction disclosed hereinafter. This invention resides substantially in the combination, construction, arrangement and relative location of parts as will be more clearly brought out in the following disclosure.

Referring to the drawings- Figure 1 is a longitudinal cross sectional view through the engine of the exhaust controlling device, and

Figure 2 is an enlarged cross sectional view 4 through the valve which controls the exhaust and provides a nonslamming effect for the engine.

It is usual in the commercial employment of fluid operated engines for operating doors and the like to provide means for preventing the slamming of the doors when movement is interrupted during the closing movement thereof. It is also usual to provide some means for preventing the slamming of the doors near the end of their closingmove ment. By means of the device of this invention both these functions are secured by means of a relatively simple control valve which may most conveniently be mounted directly on the fluid operated engine. By

- means of the construction devised by me it is possibleto secure the advantage of no leakage of fluid pressure through the exhausting cylinder when the door is held up by an obstruction during its closing movement. There is also no possibility of the door creepmg open or, .when forced partially open, to admit pressure to cause the opening movement to continue.

The arrangement of this invention also eliminates the necessity of a free exhaust port as it is now used in the cylinder of the present type-engines and as a result the piston cups will wear longer. Door engines provided with the device of this invention cause the doors to start promptly upon energization of the same, to continue with a steady movement, and prevent jamming and slamming of the doors when they are released after being held up by an obstruction.

7 Referring to the drawings, the engine is shown as comprisin a cylinder 1 having two end caps 2 and 3. glidably mounted within the cylinder are the two pistons 4 and 5 which are rigidly joined together by means of a piston rod 6. The piston rod has the toothed rack 6' thereon which meshes with a pinion .and shaft (not shown) for connection to the device to be operated. The leather piston cup 7 is secured to the-piston 4 by means of the collar 9 and nut 9'. The leather piston cup 8 is likewise secured to the piston 5 by means of the collar 10 and nut 10. Each end of the cylinder is connected through the passages 11 and 12 with the valve casmg 14 through the passages 33 and 34 which are formed in the support 13 with the valve cas-.

ing.

casing 14 for rotation on the valve stem 20. The valve 15 is provided with two ports 16 and 17 which extend only partially there the threaded opening 24. The ,chamber 22 forms a small cylinder within which a small piston 27 operates. A larger cylinder 23 is provided in alignment with the chamber 22 A. rotary valve 15 is mounted within thewithin which the larger piston 28 moves. The pistons 27 and 28 are both mounted on the same connecting rod 29 upon the end of which is provided a valve 30. The piston 28 is larger than the piston 27 and this arrangement provides what is known as a differential device.

The chamber 23 is connected by means of the pipe 25 with a passage which opens directly in the path of the ports 16 and 17. The space between the two pistons is vented to the atmosphere through the passage 26 in the cylinder wall. The movement of the valve 30 to the left is resisted by means of the spring 31. Twp exhaust ports 32 are provided in the valve and piston casing and are arranged to be disconnected with the interior of this casing when the valve 30 is seated; The lever 35 is mounted on the valve stem 20 when operating the valve.

In this disclosure the mechanism which connects the pistons and the large cylinder 1 with the device to be operated by the engine, such as doors, is notshown for sake of simplicity since it forms no part of this invention.

With the valve in the position shown in Figure 1 fluid pressure from the source is admitted through the opening 24 into chamber 22 of the valve casing 14. Since the hole 19 extends all the way through the valve 15 a fluid pressure will, therefore, pass through passages 33 and 11 to the right hand end of builds up sufficiently to move the pistons 27 and 28 to the right valve 30 will be unseated and the fluid in chamber 23 will be exhausted through the ports 32. This occurs notwithstanding the fact that the fluid pressure from the source exists in chamber 22 since the area of piston 28 is greater than that of piston 27. Should the door meet with an obstruction so as to stopthe movement of pistons 4 .and 5 the fluid will exhaust from chamber 23 until the pressure on piston 27 is greater than that on piston 28 when the valve 30 will be moved to the left..and will shut off any further exhaust of the fluid from the left hand end of cylinder'l. When the obstruction is removed from the door the pistons 4 and 5 will again begin to move to the left and when pressure in chamber 23 has been built up sufiicientlv to force pistons 28 and 27 to the right the fluid can then exhaust through the ports 32.

The relative areas of pistons 27 and 28 determine the relation between the exhaust pressure that exists in the exhausting end of the cylinder and the operating pressure. and, therefore, a constant speed operation is achieved that is not disturbed by the door being held up during the closing movement lating the speed of its operating stroke.

I am well aware that many changes in the details of construction and relative association of parts will readily occur to those skilled in the art and I do not, therefore, desire to be limited to the construction shown for purposes of illustration but rather to the scope of the invention defined in the appended claims.

What I seek to secure by United States Letters Patent is:

' 1. The combination with a fluid pressure engine for operating doors and the like having a cylinder, double acting pistons therein and a passage leading to each end of the cylinder of means communicating with said passages for controlling the admission and exhaust of fluid to said cylinder, said means comprising a valve chamber, a valve therein, a casing having connected differential pistons therein, the portion of the casing in which the smaller piston moves being in di rect connection with said valve chamber, a. connection from the valve casing to the por .tion of the casing in which the larger piston moves and a valve controlled by the larger piston for controlling an exhaust port, the valve in said valve casing controlling the flow f fluid from the exhausting end of the engine cylinder. the differential pistons and the valve controlled by; the larger piston acting to cut off the exhaust of fluidfrom the engine cylinder when the door meets an obstruction. 2. The combination with a fluid pressure engine for. operating doors and the like hav-.

ing a cylinder, double acting pistons therein and a passage leadingto each end of the cylinder of means communicating with said passages for controlling the admission and exhaust of fluid to said cylinder, said means comprising a valve chamber, a valve therein, and a'casing having connected differential pistons therein. the portion of the casing in which the smaller piston moves being in direct connection with said valve chamber, a connection from the valve casing to the portion of the casing in which the larger piston moves and a valve controlled by the larger piston for controlling an exhaust port, the valve in said valve casing controlling the flow of fluid from the exhausting end of the engine cylinder, the differential pistons and the valve controlled by the larger piston acting to cut off the exhaust of fluid from the engine cylinder when the door meets an obstruction, said valve in said casing acting in conjunction with said passages to open either end of the engine cylinder to admission or exhaust of fluid.

3. The combination with a fluid pressure engine for operating doors and the like having a cylinder, a double acting piston therein and a passage leading to each end of the cylinder of a valve casing, a valve in said casing for controlling said passages, a fluid pressure 1 connection to said casing, a differential piston structure including a casing; an exhaust valve controlled by said differential piston structure, means for applying fluid pressure to the smaller area of said diflerential piston structure and a connection between said first mentioned valve and the end of the casing in which the larger area of said difi'erentialpiston structure operates, said exhaust valve acting to open the differential piston casing to the atmosphere when the force produced by the pressure therein acting on the larger area of the difl'erential piston structure is greater than the force produced by the pres- 2:5 sure acting on the smaller area of the differential piston structure.

In testimony whereof I have hereunto set my7hand on this 22nd day of October A. D. 192

HAROLD ROWNTREE.

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