GB2054062A

GB2054062A - Pump for pumping gaseous and/or liquid media

Info

Publication number: GB2054062A
Application number: GB8020275A
Authority: GB
Original assignee: Fried Krupp AG
Current assignee: Fried Krupp AG
Priority date: 1979-06-28
Filing date: 1980-06-20
Publication date: 1981-02-11
Also published as: FR2460401A1; JPS5620783A; FR2460401B1; DE2926035A1; GB2054062B

Abstract

A pump for gases or liquids has a pump chamber 1 made entirely of a memory alloy which changes shape in response to changes in temperature. A heating and cooling jacket 4 and an insulating lining 5 are provided. <IMAGE>

Description

SPECIFICATION Pump for pumping gaseous and/or liquid media The invention relates to a pump for pumping gaseous and/or liquid media, which consists in substance of a closed chamber, in which the energy for pumping is provided by use of the memory effect and which includes no mechanical parts which move in relation to one another.

Conventional pumps are generally mechanically driven. The suction required for pumping is produced by movement of a reciprocating or rotary piston or by other mainly generally rotary compressors. The pumping efficiency attained thereby is relatively small. The operation of the pumps is also uneconomic due to the maintenance necessary at regular intervals. Some improvement is provided by steam- or liquiddriven jet pumps but the yield of energy is still unsatisfactorily low. Moreover the field of use of these pumping systems is limited in that, for example, they are not suitable for use in space.

It has also been proposed to utilize the memory effect in pumping systems. The memory effect can be simply explained as martensitic change in structure of certain alloys, for example AuCd, CuAINi, or NiTi. The result is that, for example, a bent wire of such a memory alloy will assume its original shape and thereby perform work when heated to a specific changeover temperature peculiar to each alloy. The so-called irreversible and reversible portions are to be distinguished. For the reversible portion of the memory effect, which is to be used for pumping, it is sufficient to predeform the memory element plastically in order to generate the memory effect by change in the surrounding temperature. The memory effect can be influenced in various ways, for example, it is increased by a slight loading of the element during cooling.This permits the energy transformation of low temperature heat into mechanical work in a simple manner.

Thus U.S. Specification 3827426 describes a pump for liquids, intended for use as an artificial heart, in which the pumping action is produced by contraction and expansion in response to temperature changes in Nitinol wires. The contractile wires can be wound helically or crosswise around the chamber of the pump so that they effect pumping movements. The energy required for control of such an artifical heart is produced electrically. This system has the disadvantage that during the movements of the Nitinol wires it is necessary to overcome frictionai forces resulting from the movement in relation to the chamber. The friction is increased when the wires extend crosswise, i.e. when a twodimensional contraction and expansion are to be produced.This disadvantage excludes the use of this pumping system from space travel owing to the risk of cold welding arising from relatively moving parts.

It is accordingly the object of the invention to provide a pump in which the above disadvantages are avoided and which operates in a simple manner requiring a minimum of maintenance. This object is fulfilled in that the pump chamber is made entirely of a memory alloy. This pump has the advantage that it requires no mechanical auxiliary parts and avoids relative movement of two parts of the pump. Furthermore the invention makes it possible to use the element exhibiting the memory effect not only as a controlling but also as a structural element. Advantageously the pump chamber exhibits a repeatable biaxial memory effect which renders possible a high pumping efficiency.

According to a further feature of the invention the pump chamber is made of a memory alloy containing about 55% nickel, the balance titanium. With such an alloy it is possible to limit the changeover temperature releasing the memory effect to about 500C. Such a temperature can often be established by the use of heat available in cooling water or in waste gases.

The pump chamber is advantageously associated with pipes for supply and withdrawal of liquid- or gas-supplied heat necessary for the temperature control.

According to a further feature of the invention the pump chamber has at least two valves for inlet and outlet of the medium to be pumped. These valves are advantageously controllable by the memory effect. This can be achieved by a switch actuated by the memory effect. In this simple manner all the energy required for operation of the pumping system can be supplied from a single source of heat.

If the medium to be pumped should not be subjected to the temperature variations required for release of the reversible memory effect the inner wall of the pump chamber is provided with a thermally insulating lining.

An embodiment of the invention is shown in the drawing, which shows a pump consisting of a pump chamber 1, inlet and outlet valves 2 and 3 and a heating and cooling jacket 4. In addition the chamber has an insulating lining 5 which prevents transfer of energy from the chamber to the medium to be pumped.

The chamber is piastically pre-deformed so that by hot/cold temperature cycles the reversible portion of the memory effect can be repeatedly brought into operation. At the start of a pumping cycle the valve 3 is closed and the valve 2 is opened, so that the medium to be pumped can flow into the interior 6 of the chamber. The valve 2 is then closed and the valve 3 opened and heating, in fhis case electrical heating, is switched on. The heating of the wall of the chamber 1 causes it to contract and part of the medium to be pumped to flow through the valve 3.

The valve 3 is then closed again and the valve 2 opened. At the same time the wall of the chamber is cooled by means of cold water which flows over the outer surface of the chamber 1. This causes the chamber to expand and a corresponding amount of the medium to flow into the interior 6 through the valve 2. After closing the valve 2 and simultaneous opening of the valve 3, heating of the chamber starts the next working cycle.

The heating and cooling of the chamber can be by radiation, convection or thermal conduction. It is also possible to heat the chamber 1 by direct exposure to the rays of the sun. It is equally possible to cause contraction and expansion of the chamber by hot and cold water which flow alternately through tubes in heat transmitting contact with the wall of the chamber. It is also possible to conceive of a construction in which the wall of the chamber is only partly constructed of a memory alloy.

Claims

1. A pump for pumping gaseous and/or liquid media, which consists in substance of a closed chamber, in which the energy for pumping is provided by use of the memory effect and which includes no mechanical parts which move in relation to one another, characterised in that the pump chamber is made entirely of a memory alloy.

2. A pump according to claim 1, characterised in that the pump container is so plastically predeformed that it possesses a repeatable, biaxial memory effect releasable by a change in temperature.

3. A pump according to claims 1 and 2, characterised in that the chamber is made of an alloy containing about 55% nickel, the balance titanium.

4. A pump according to claims 1 to 3, characterised in that the transition temperature releasing the memory effect is about 500C.

5. A pump according to claims 1 to 4, characterised in that the outer wall of the chamber is associated with means for supplying and withdrawing liquid or gas.

6. A pump according to claims 1 to 5, characterised in that the chamber has at least two valves.

7. A pump according to claims 1 to 6, characterised in that the valves are controllable by the memory effect.

8. A pump according to claims 1 to 5, characterised in that the inner wall of the chamber has a lining of thermally insulating material.