DE61760A - Boiling liquid pressure generator for remote motion transmitters - Google Patents

Description

IMPERIAL

PATENT OFFICE.

Apparatuses in which pressures generated by heating or otherwise are propagated through air-filled tubes (pneumatic) and used to move membranes are known, as are those in which the membrane movement is used to operate valves, slides or electrical contacts; from this there is the advantage that this operation is possible from a point outside the housing at any distance and a stuffing box does not need to be used. The type shown in FIG. 1 can apply as a type of such a known device. The completely sealed space A, which the membrane m ¹ closes off, is filled with air. This whole component shall be referred to as pressure generator A. The line !, with the associated extensions e and e ¹ and the membrane m, is called transformer L. The transmitter is also completely sealed and filled with air.

If a pressure is exerted on the membrane m ^] by heating the air in the pressure generator .4, m ¹ is pushed into the space of L and there the air is compressed. The expansion of the same causes a propulsion of the membrane m and a movement of the valve v. If the air in A cools, the membranes retract again.

By omitting the membrane m ¹ , a simplified form is obtained in which the heating can be carried out at any point on the transmitter (the line), which now also serves as a pressure generator.

The main drawback of such pneumatic apparatus, which is a successful application which in most cases prevents it from being used for practical purposes consists in the fact that the pneumatic Pressures, which in practice applicable dimensions and temperature differences can be generated, are often not sufficient to achieve the forces which are necessary to produce the desired movements and especially to ensure the tight closure of valves guarantee.

The following innovations counter this disadvantage:

a) inclusion of a drip liquid boiling at a certain temperature in the pressure generator A ;

b) Arrangement of a vacuum in A next to the boiling liquid enclosed there;

c) Replacement of the compressible air in the transmitter by an incompressible one (drip) liquid, i.e. replacement of the pneumatic transmission by a hydraulic one.

The mode of operation of the device provided with the innovations is as follows:

By heating at A (pressure generator) to a temperature i °, which is above the boiling point of the enclosed liquid, saturated vapor is generated at the pressure which corresponds to i °. The whole pressure is transferred by means of the diaphragm "j ¹ and the liquid in the transformer and to the connected to the valve membrane.

When A cools down again, the enclosed vapor condenses, along with the liquid.

If there is a vacuum, the two membranes together with the transfer fluid are pressed towards A by the external air pressure, which acts here almost in its full strength, and the entrained valve ν is actuated with a force which cannot be achieved with a pneumatic apparatus.

In the simplified form only a part evaporates where the pipe is heated the boiling liquid, the rest takes care of the hydraulic transmission. When cooling The steam condenses again, a vacuum is created and the external overpressure bends it Membrane back on.

How extraordinarily great is the increase in the effects of forces which are produced by application the specified innovations is achieved with otherwise the same spatial dimensions of the apparatus, the following example may show.

The dimensions of an apparatus according to FIG. 1 are as follows:

Volume of the pressure generator A ioo cubic centimeters, volume of the transformer L V ₀ = 1000 cubic centimeters, spatial displacement m through the membrane ^x 5 cubic centimeters, available temperature limits io ° and 180 ⁰ C.

i. The filling is air with the pressure of one atmosphere at io ^Q C.

The pressure with which the valve is pulled into its position by the membrane at 10 °, is zero, another force, such as the weight of the valve, has to do this.

If the air in A is heated to 180 °, its pressure increases when p _{0 is} atmospheric pressure:

( 1

P = Po l +

273

thus around ρ - p ₀ = p ₀

180
273

di slightly less than _{^2/3 of} atmospheres.

However, this excess pressure cannot be fully transferred to the membrane m . The overpressure in A can only depress the membrane m ¹ by its entire length, ie it can produce a volume reduction of 5 cbcm in the transmitter.

. If p ^{1 is} the pressure of the air filling in the reduced volume (v ₀ - $), it is known

Po
the

"0-5
Pressure increase

or, because V ₀ = 1000 cbcm,

P —Po

Po

- The atmosphere.

191

But this overpressure only has this small value as long as the membrane m does not give way.

2. Let the filling in the pressure generator A be air, that in the transmitter L an incompressible liquid. Now the full, generated in A positive pressure is therefore slightly less transmitted as _^2/3 atmosphere m to the diaphragm.

3. Let the filling in the pressure generator be water, next to a small vacuum, that in the transmitter an incompressible liquid, e.g. B. glycerin.

In a vacuum, the pressure of the water vapor at 10 ^° C. is ₈₂ atmospheres.

The overpressure from outside on the membrane m, which pulls the valve into its seat, is thus:

ι '81 ·

ι ^ - = --— atmosphere.

82

So about ι kg per square centimeter.

If the water in room A is at 18o °
warms, then the pressure of the saturated steam, which is now generated, is about 10, the excess pressure is 9 atmospheres.

The transmitter L transfers all of this pressure to the membrane m, which moves the valve.

A comparison of the results shows:

Apparatus without
Innovations

Apparatus with

the
Innovations

O at

8l
"82"

at

at

9 at

Overpressure from outside
on the membrane
io ⁰ C. (conclusion of

Valve)

Overpressure from inside
on the membrane
18o ° G. (opening of 191
Valve)

In addition to the very vigorous operation, which takes place with relatively great pressure, the device provided with the innovations also has the advantage that the effect takes place very quickly at the moment when the boiling temperature of the liquid in A is exceeded or undershot.

Another essential advantage is the fact that the boiling point of a liquid with the pressure changes. This can be used to determine the temperature at which the activity should be changed by the fact that one z. B. the valve more or less burdened.

As an example of an application of the innovations described, FIGS. 2 and 3 show a luminous gas discharge that works automatically when the flame is extinguished.

Thin-walled tubes serve as pressure generator A and transmitter L , which, like space e , is filled with a liquid boiling at about 80 ° (benzene and other hydrocarbons have proven their worth).

By pulling the valve ν when the burner is cold, the membrane m is pulled down a little against the force of the external air pressure on it. This creates a

Claims (4)

on the one hand a small vacuum inside, on the other hand the valve is opened with the full force of the pressure acting on the diaphragm in its seat. If the flame of a match is brought to d , the liquid in L boils almost instantaneously, the membrane m is expanded and the valve is opened, luminous gas escapes and ignites. A heating cap h now conducts the heat of the flame to A, so that at this point a vapor bubble always remains inside the tube, which is sufficient to keep the valve open. When the flame goes out, the vapor condenses and the valve is closed by the acting on the membrane, as previously described, with great force in its Pressed seat. The whole gives a safety device to prevent gas leakage Leaving taps open. Patent claims: The motion transmitters, consisting of a pressure generator (A) with a flexible plate (m ¹ ), a pipe (L) filled with dripping liquid and a flexible plate (m) for moving a closing device (valve, slide, etc.), an electrical one, act on remote The pressure generator is designed in such a way that its cavity is partly filled with a boiling liquid, but partly remains empty, so that the plate (m) when the temperature rises above the boiling point of the enclosed liquid due to the development of steam The excess pressure that occurs is pressed outwards, and when it sinks below the boiling point, it is sucked inwards by excess pressure occurring as a result of precipitation. 2. A device of the type mentioned under i. characterized type, in which the flexible plate (m ¹ ) between the pressure generator and pressure line is omitted, so that part of the drippable line liquid serves at the same time as boiling liquid. 3. To change and regulate the boiling point of devices under 1. and 2. marked type the addition of a printing device with changeable Load through which the voltage of the line and the boiling liquid for the desired boiling point the latter can be adjusted. 4. When using the device marked under 1. and 2. for the production of an automatic closing device for the gas line when a gas flame is extinguished, the addition of a heating cap made of heat-conducting material (h), which transfers the heat from the flame to the boiling liquid. 1 sheet of drawings.