US2002329A - Pressure medium conduit - Google Patents

Description

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May 2l, 1935. E. MLLER 2,002,329

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Patented May 21, 1935 UNITED STATES PATENT OFFICE PRESSURE MEDIUM CONDUIT Application October 12 1932, Serial No. 637,378

In Germany October 15, 1931 3 Claims.

The subject of this invention is an apparatus which serves to increase the velocity of a pressurevarying impulse in a pressure-medium conduit.

Such an apparatus has been proposed in which special valve-like devices are connected to the pressure-medium conduit, which transmit the energy of an introduced pressure-varying impulse from one section of the conduit to another, with a velocity greater than that of sound in air.

In the application of this apparatus to a pressure-medium brake for railway vehicles, which has already been proposed, a valve apparatus is provided as close as possible to each end of the vehicle, and both are connected together for example by a draw Wire, which is attached directly to the piston of the accelerator valves, which act to release pressure medium from the conduit.

This arrangement does not yet appear to be suiciently complete. It is in the nature of the accelerator that the smaller the pressure impulse to which the accelerators respond can be kept, the greater is the velocity of transmission, as the effective pressure impulses are not propagated through the couplings in an ideal perpendicular wave front, but with a temporarily rising one. In practice it is not possible to arrange the Wires connecting the accelerators in the individual cars so that the friction conditions are the same in all the cars. The result of this is that wagons with higher wire friction give a delayed response, and the total time of transmission is undesirably lengthened. An unnecessary delay can also occur when, in the course of time, the wires have become harder to move due to rust formation or to dirt collecting on them. 'I'his would appear especially undesirable in cases where, in a train provided with accelerators of the type indicated above, cars are included without such apparatus, as it is known that a wave front in air becomes more flattened the longer is its path.

The problem of the invention is to overcome this defect. According to the invention this is done by completely withdrawing the piston, which determines the response of the accelerator, from the inuence of the wire, so that it no longer comes into contact with the wire. The piston is formed as an independent piston which is under the conduit pressure on one side and under the control chamber pressure on the other side, and commands a valve which controls the movement of a special piston connected with the draw wire.

The apparatus according to the invention is shown schematically in the drawing in ve constructional examples. Forms of construction (Cl. 30S- 82) have been chosen as examples in which each piston of the pair of accelerators carried on a car is connected by a draw wire with the outlet device of the other accelerator, whereby this outlet device permits conduit air to flow, not directly into the atmosphere but into a chamber.

In view of the fact that the two accelerators belonging to one car are counterparts and completely resemble one another constructively and are mounted at opposite ends of the vehicle in the manner of mirror images, in the ve figures of accelerators of various types of construction the left hand accelerator only (from the point of View of the observer) carried on the vehicle is shown.

The piston 4, acted on by compressed air from the brake pipe I, has a hole 3 through which a control chamber 5 is filled to the pressure ruling in the main conduit. A piston 26 can be operated by compressed air from the control chamber 5 through a valve 25 controlled by the piston 4. The other side of the piston 26 is normally connected with the free air through a receiving chamber II and hole I2. The piston 26 is firmly connected through the draw wire 6 with the spring loaded valve 9 of the right hand accelerator, not shown in the drawing, whose piston 26 in turn is firmly connected through the draw wire 6a with the spring loaded valve 9 of the left hand accelerator shown. When the second mentioned piston 2E is moved to the right this valve 9 allows compressed air from the main conduit to reach the receiving chamber II.

It is desired to keep the dimensions of the receiving chamber as small as possible, so that the brake accelerator may also be small. For this reason the subject of the invention as shown in Figure 1 is very much simplified by forming the guide tube 21 surrounding the wires 6 and 6a as a part of the receiving chamber, as shown in Figures 2 to 5. In this connection the guide tube 21 does not need to be particularly air tight; it may be so connected to the brake accelerator that the hole I2 in the receiving chamber can be omitted.

The method of operation of the apparatus is as follows:-

If the pressure in the main conduit I is reduced, and the pressure-varying impulse coming from the left reaches the accelerator, the piston 4 of this latter is moved upwards by the pressure in thc control chamber 5, which cannot equalize itself quickly through the small hole 3 in the piston with the pressure in the main conduit I, and the valve 25 is opened. The piston 26 is then actuated by compressed air from the control chamber 5 and moves towards the left. By this movement the valve 9 of the second accelerator (not shown) which is firmly connected by the wire 6 with piston 26, is opened against the pressure of its loading spring; compressed air from the main conduit I reaches the receiving chamber II and causes a reduction of pressure at the other end of the car, which is at once transmitted to the accelerator of the next car. The left hand side of the piston 26 is acted on by compressed air reaching the receiving chamber II, and after a certain pressure has been reached this, in conjunction with the spring which loads the valve 9, causes the closing of this latter. By this means no more compressed air is drawn ofi from the main conduit I than is necessary for the purpose. The compressed air from the receiving chamber I I escapes slowly through the hole I2 into the atmosphere; as, when the compressed air from the receiving chamber 5 is given up to the cylinder of the piston 26, the piston 4 is again moved downwards by the conduit pressure and closes the valve 25, the compressed air which is on the right hand side of the piston 26 reaches the left hand side, either owing to the piston 26 not being an air tight t or through a narrow nozzle, and from there also passes out into the atmosphere.-

A particular advantage of this arrangement consists in that when the valve 25 is opened the piston 26 receives the full pressure of the control chamber. A very definite pressure wave is thereby propagated through the Wire, which manifests itself in high velocities of valve opening. The further result is obtained that the piston 26 need only be very small and thereby the piston 4 which is directly influenced by the conduit pressure, and thc control chamber 5 of this piston, can be substantially reduced in comparison with constructions already proposed.

Naturally, the piston 26 instead of being actuated by control chamber air, may be actuated by compressed air from a special chamber (Figure 4) or from the main conduit (Figure 3). Further, the movement of the piston 26 can take place in such a way that there is at first pressure acting on both its sides, which is reduced or removed on one side, with reduction of pressure, in the main conduit, by means of the valve 25 (Figure 5) What I claim and desire to secure by Letters Patent of the United States iszl. In connection with a pressure medium conduit and particularly a compressed air brake pipe extending the length of a railway car, a pair of valve housings connected to said brake pipe and spaced apart so that one housing is disposed at each end of said car, a control piston movably disposed in one of said housings and having a draw wire secured thereto connecting said piston with an outlet valve in a valve housing xedly associated with the other housing at the other end of the car, a second control piston movably disposed in said other housing also having a draw wire secured thereto and connecting said second piston to a second outlet valve in a valve housing which is flxedly associated with the first one of said housings, means resiliently tending to close said outlet valves, each of which outlet valves when open, admits air from said brake pipe into a chamber provided with means for releasing air therefrom at a predetermined rate of flow. a pressure medium storage chamber formed in each of said first pair of housings, a pair of additional valves individually disposed in said first pair of housings and interposed between said control pistons and the storage chambers in said pair of housings so as to individually control transmission of air from said storage chambers to the control pistons, and a pressure responsive piston both interposed between the storage chamber in each of said pair of housings and the supply thereto of pressure medium from said brake pipe and effective to open the one of said additional valves respectively associated with and controlling transmission of air from said latter storage chamber in each case.

2. Brake control apparatus according to claim 1, wherein the pressure responsive piston in each of the pair of housings is provided with means which are effective to gradually transmit air pressure to the storage chamber associated with the piston in each case from the brake pipe while preventing any sudden flow of pressure medium from said storage chamber toward said brake pipe.

3. Brake control apparatus according to claim 1, wherein the pressure responsive piston in each of the pair of housings is provided with means which are effective to gradually transmit air pressure to the storage chamber associated with the piston in each case from the brake pipe while preventing any sudden flow of pressure medium from said storage chamber toward said brake pipe, while the control pistons are constructed to allow air to escape from between the same and the additional valves when the latter individually close and the outlet valves controlled by said pistons in either case tend to close.

ERNST MLLER.

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