US2077515A - Air brake - Google Patents

Description

April 20, 1.937. g. A. CAMPBELL 2,077,515

AIR BRAKE Filed Nov. 25, 1934 5? 2 55 y as I Ema/.8

IL I 46z Jnventor (Ittomegs Patented Apr. 20, 1937 UNITED STATES AIR BRAKE Charles A. Campbell, Watertown, N. Y., assignor to The New York Air Brake Company, a corporation of New Jersey Application November 23, 1934, Serial No. 754,489

10 Claims.

This invention relates to air brake systems and particularly to automatic means for draining Water from the main reservoir.

The accumulation of water which condenses from the compressed air in the main reservoir, is a Well known source of operating difficulties. Heretofore various means for periodically draining off this water have been proposed, but none known to me has proved successful under practical operating conditions. Some of the prior art devices were intended to operate periodically in response to application or release of the brakes.

The present invention falls in this general class but involves novel features which enable it to meet the practical requirements 'of service.

The device includes a venting drain valve and a timed actuating means, which when put into action, preferably by the development of brake cylinder pressure, opens the vent valve, holds it open for a definite time interval and then closes it. This time interval is so chosen with reference to the capacity of the vent, and the probable maximum accumulation of water between venting actuations, that when the valve opens it will stay open at least long enough for the maximum accumulation of water to be swept through and clear of the valve. In practice the valve can be designed to operate in this waywith an open period of about second.

The valve is mounted above the reservoir, or at any rate above the highest water level contemplated, and its water intake connection is preferably in the form of a dip pipe leading to a sump formed in the lowest portion of the reservoir.

Consequently water is not retained in the valve between actuations thereof, but at each actuation the valve is swept clear of water and remains free of water until it again functions.

Because of the features above enumerated the tendency of the valve to freeze up in cold weather is minimized or completely eliminated. In prior art devices the water accumulated in or near the valve and freezing up was a common cause of failure in Winter.

Another feature conducive to certain and precise operation is the use of flexible diaphragms in lieu of pistons, Their free movement offers certainty of operation, and their small displacement permits precise timing with a timing chamher of minimum volume, a feature of moment Where actuations are frequent and the timing air cannot be otherwise usefully applied.

Another feature of the invention is the use with the automatic valve of a second manually operable valve whose mount sorvesas a sumpfrom which the dip pipe of the automatic valve leads.

Other novel and useful features will be recognized from a consideration of the description of a preferred embodiment illustrated in the accompanying drawing. 5

In the drawing,

Fig. 1 is a vertical axial section through the automatic drain valve.

Fig. 2 is an elevation, partially broken away, showing two main reservoirs connected in tandem l0 and automatic drain valves, one connected with each reservoir, and both arranged to be put into action by pressure developed in the brake cylinders.

Referring to Fig. 2, the main reservoir volume 15 is made up of two drums 4 and 5, connected'at 6 and supplied with compressed air through pipe 1 which leads from the discharge of the usual compressor (not shown). The brake system is fed with compressed air by an engineers brake 20 valve of any suitable form (not shown) such brake valve being connected to pipe 8.

The operation of the brake valve admits and exhausts air to and from brake cylinders 9, either directly or through automatic valves (not shown), 25 depending on the type of brake system used. The type of system is immaterial. Pipe II is connected with the cylinders 9 and hence is subject to whatever pressure exists from time to time in the cylinders. 30

Screwed into an aperture at the lowest point in each drum is a fitting l2 which forms a small sump I 3, and attached to the lower side of the fitting is a manually operable drain cock l4. Opening of the cock will drain the sump and con- 35 sequently the corresponding drum. This is useful on dead equipment or in case of derangement of the automatic valve.

Diametrically opposite each fitting l2 and hence at the top of the corresponding drum a 0 bushing I5 is screwed into an aperture in the drum and carries a dip pipe l6 whose open lower end is in sump I3. Screwed into each bushing I5 is a corresponding 90 pipe bend I! which leads to a corresponding drain valve. 45

As the two drain valves are functionally and mechanically identical, a description of one will suffice, and such description will now be given with reference to Fig. 1.

The housing of the main valve comprises four 0 components, a main body 2!, a rear cap 22, a front cap 23 and a combined diaphragm seat and baffle 24 mounted within the front cap.

In the main body 2| is an annular timing chamber 25 separated by an annular wall 26 and dished 55 head 21 from a combined valve chamber and diaphragm chamber 28. At the rear end of chamber 28 is a port surrounded by the annular bead or valve seat 29. A passage 3| leads from cham- 5 ber 25 to the port through said seat.

In the rear end of body 2| is a recess or cavity 32 having a marginal seat for the periphery of a combined gasket and flexible diaphragm 33, of rubber-like or other suitable material. The periphery of member 33 is clamped against the seat by the rear cap 22 which is bolted in place as shown and encloses a chamber 34 on the outer side of the diaphragm.

Chamber 34 is connected by passage 35 with pipe 36, which is screwed into the tapped open.- ing 31. A gasket 38 prevents leakage from passage 35. Thus diaphragm 33 is forced inward (to the right, in the drawing) when pressure builds up in the brake cylinders.

In chamber 32, and in thrust relation with the inner face of diaphragm33, is a disk 39 mounted onthe. end ofv atubular member 4!. Member 4| slides axially'and fits closely in a guideway formed in body 2| and. leading through passage 3| and seat 29. The inner end of tubular member 4| is tapered as shown and adjacent disk 39 there are; through ports 42, four being indicated.

The disk 39 carries an annular: gasket 43 which attheinner limit of: motion of diaphragm 33 and disk 38 seals on a seat 44 formed in body 2|. A

choke 45is. mounted in the bore of tubular member 4| and limits the fiow therethrough. The chamber: 32 is vented to atmosphere at 46.

The front cap 23 has at its front center a tapped connection 41 for'pipe There is also a tapped. bottom. connection 48 for a drain pipe 49', which may lead; to any'suitable point of discharge. Both connections 41 and 48 communicate with a chamber 5| and the first-named is surrounded by a valve seat bead. 52. There is also a tapped connection 53: which leads to chamber 54 between a pair of differential diaphragms about to be described. A pipe 55 conducts main reservoir air from. pipe 8 through. filter 56 to chamber 54, so that this chamber is always. subject to main. reservoir pressure.

The diaphragms just. mentioned are. a large diaphragm 51 and a small diaphragm 58, each.

of which. isof rubber-like or other suitable material, and each of which is clamped at its periphery and there functions as a gasket. The. smaller diaphragm is clamped by spacer 24 against a seat in cap: 23, and the larger is clamped between the spacer 24 and cap 23, on the one: hand, and. body 2| on the other. The spacer 24 has' a port: 59 of moderate capacity and serves as. a. baflie between connection 53 and the center portion of chamber A flanged spacer 6| connects thecenters ofthe 60 diaphragms 51 and 58'and has bosses which extend through holes at the centers of the. diaphragms. A disk 62 andv nut 63? are used to en:- sure a sealed connection to diaphragm 51. A port 64 of limited fiow capacity leads through 65 spacer 6| and oifers a moderately restricted connection' between chambersv 54 and 28..

Similarly a sealed connection with. diaphragm 58 is. secured by the use of valve disk 65 and screw 66. Disk 55 has an annular recessin which is fixed a gasket 61 which normally seals against seat 52.

Guided in chamber 28 and normally engaging seat 29 is a valve 68 here shown as composed of rubber-like material. It' is stiffened by a metal disk 69 having a serrated periphery which serves to center the valve in chamber 28. A coil compression spring H is interposed between the valve 38 and the nut 63 on the spacer 6|.

Operation Under normal running conditions with brakes released, chambers 54 and 28 are at main reservoir pressure, with valve 68 closed against seat 29. Hence pressures on the opposite faces of diaphragm 51 are equal and main reservoir pressure acting on diaphragm 58 holds valve gasket 61 against seat 52. It will be observed that the area within seat 52 is smaller than the effective area of diaphragm 58.

At this time brakes are released so chamber 34 is at atmospheric pressure. Tubular member 4| is retracted, allowing valve 68 to seat and venting chamber. 25. to atmosphere via passage 3|, choke 45, ports. 42, chamber 32 and passage 46.

When a brake application is made diaphragm 33v will be forced inward. Member 4| first seals on valve; 68 and then unseats the valve. This substantially closes the vent from. chamber 25, but gasket 43 produces a complete seal when it engages seat 44. The effect is to connect chambers 25 and 28 through alarge port, putting diaphragm 51 out of balance and causing valve 65 to open. Flow at oncestarts from chamber 54 through port 64 to chambers 28 and 25, which are connected as described. When equalization is approached valve 65 will again close.

The parts are so proportioned that the duration. of the open condition. of valve 65 will ensure the discharge of all water likely to be present, so that sump |3,.pipes I6 and I5, and chamber 5| are swept clear. A. period of about /2 second is preferred in practice, but this may be modified to suit particular cases. Timing can be changed by changing, for example, the capacity of port 64 or the volume of chamber 25.

When the brakes are released the retreat of diaphragm 33 and member 4| allows valve 68 to close and then vents chamber 25, conditioning the device for. another operative cycle. It should be noted that choke 45 delays the venting of chamber" 25, so that a quickly repeated brake application will not open the drain valve or will open it for: a shorter period. While the various details are all considered useful, they are subject to modification, and some may in certain cases i be omitted. The specific embodiment described is intended to be illustrative and not limiting.

For example, the development and subsequent release of pressure in chamber 34 will cause the valve to perform its operative cycle. This should occur periodically and connection with a brake cylinder or cylinders is a familiar expedient and one already proposed in this art. It is recognized, however, that chamber 34 might be connected to any space in which a suitable operating pressure is temporarily developed from time to time. The size of diaphragm 33 may, if necessary, be modified according to the pressure so available.

What is claimed is,--

1. The combination of a brake system includ ing a reservoir; a normally closed drain valve for discharging liquid from said reservoir; a pressure motor arranged to be actuated by pressure fluid derived directly from said reservoir, connected to actuate said valve and arranged when put into action to perform a timed cycle in which it opens said valve for a definite period, then closes the same and ceases to act; and valve means distinct from said brake system but responsive to pressure variations in a portion of said brake system other than said reservoir for putting said motor means into action.

2. The combination of. a brake system including a reservoir; a normally closed drain valve for discharging liquid from said reservoir; a pressure motor arranged to be actuated by pressure fluid derived directly from said reservoir, connected to actuate said valve and arranged when put into action to perform a timed cycle in which it opens said valve for a definite period, then closes the same and ceases to act; valve means distinct from said brake system but responsive to pressure variations in a portion of said brake system other than said reservoir for putting said motor means into action; and means associated with said motor means and serving to prevent the same from being put into action for a definite period following the performance of an operative cycle.

3. The combination of a drain valve; means urging said valve closed; motor means connected to actuate said valve and comprising a pair of Working spaces separated by a movable abutment, there being a restricted pressure equalizing connection between said spaces; means for supplying pressure fluid to one working space and thence through said equalizing connection to the other working space; a timing chamber; valve means serving to connect said timing chamber selectively to exhaust and to said other Working space; and means for shifting the last-named valve means.

4. The combination of a drain valve; means urging said valve closed; motor means connected to actuate said valve and comprising a pair of working spaces separated by a movable abutment, there being a restricted pressure equalizing connection between said spaces; means for supplying pressure fluid to one working space and thence through said equalizing connection to the other working space; a timing chamber; valve means serving to connect said timing chamber selectively to exhaust and to said other working space; means for shifting the last-named valve means; and means for delaying the exhaust of pressure fluid from said timing chamber.

5. The combination of a brake system including a reservoir; a drain valve arranged to discharge liquid from said reservoir; means urging said valve closed; motor means comprising a pair of working spaces and a movable abutment interposed between said spaces, there being a restricted pressure equalizing connection between said spaces; an operative connection between said abutment and valve; means for supplying pressure fluid to one of said working spaces and thence through said equalizing connection to the other of said working spaces; a timing chamber; valve means serving to connect said timing chamber selectively to exhaust and to said second working space; and motor means responsive to pressure in a portion of the braking system for shifting the last-named valve means.

6. The combination of a drain valve; motor means comprising a pair of working spaces and a movable abutment subject to the opposing pressures in said spaces, there being a restricted pressure equalizing connection between said spaces; an operative connection between said abutment and valve; means for supplying pressure fluid to one working space and thence through said equalizing connection to the other working space,

means comprising a movable abutment subject to pressure in the first-named working space and connected to urge said valve in a closing direction; a timing chamber; valve means serving to connect said timing chamber selectively to exhaust and to said second working space; and means for shifting the last-named valve means.

7. The combination of a drain valve; motor means comprising a pair of working spaces and a movable abutment subject to the opposing pressures in said spaces, there being a restricted pressure equalizing connection between said spaces; an operative connection between said abutment and valve; means for supplying pressure fluid to one working space and thence through said equalizing connection to the other working space; means comprising a movable abutment subject to pressure in the first-named working space and connected to urge said valve in a closing direction; a timing chamber; valve means serving to connect said timing chamber selectively to exhaust and to said second working space; means for shifting the last-named valve means; and means for delaying the exhaust of pressure fluid from said timing chamber.

8. The combination or a drain valve; means urging said valve closed; motor means connected to actuate said valve and comprising a pair of working spaces separated by a movable abutment, there being a restricted pressure equalizing connection between said spaces; means for supplying pressure fluid to one working space and thence through said equalizing connection to the other working space; a timing chamber; a normally closed poppet valve controlling the communication between said timing chamber and said other working space; a shiitable member having a discharge port through which said timing chamber is normally vented; and means for shifting the last-named member into sealing engagement with said poppet valve to close said discharge port and then unseat said poppet valve.

9. The combination of a drain valve; means urging said valve closed; motor means connected to actuate said valve and comprising a pair of working spaces separated by a movable abutment, there being a restricted pressure equalizing connection between said spaces; means for supplying fluid to one working space and thence through said equalizing connection to the other working space; a timing chamber; a normally closed poppet valve controlling the communication between said timing chamber and said other working space; a shiftable member having a discharge port through which said timing chamber is normally vented; and fluid pressure operated means for shifting the last-named member into sealing engagement with said poppet valve to close said discharge port and then unseat said poppet valve.

10. The combination with a receiver having a liquid-collecting sump, of a drain valve connected with said sump and located wholly above the liquid level therein; motor means capable of being put into action to open said valve and then after a definite time interval, sufficient to ensure discharge of substantially all liquid from the sump, to close said valve; and means rendered effective by the performance of one such cycle to preclude its recurrence for a definite time interval.

CHARLES A. CAMPBELL.

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