DE10134831C1 - Closure device for a tubular line for conveying a gaseous or liquid medium - Google Patents

Abstract

The closure device (7) of a tubular line (8) with an inner diameter (R¶i¶) widened in a groove or groove-like manner in a closure region has a closure element (6) with an outer diameter that is enlarged in an assembled state compared to the inner diameter. At least the ring-shaped outer edge region (4) of the closure element (6) is to consist of a shape memory alloy which exhibits superelastic properties and which is introduced into its comparatively harder austenite phase when it is introduced into the expanded closure region (9).

Description

The invention relates to a closure device egg ner tubular line for conveying a gaseous or liquid medium, which has a predetermined inner diameter, which is widened like grooves or channels in a closure region, with a closure element, which

• - In an assembled state one compared to the inside diameter the cable has an enlarged outside diameter,
• - Elastic at least in an annular outer edge area is trained

and

• - Can be inserted into the sealing area of the line, where jamming occurs.

For closing tubular lines or line systems systems in which gases or liquids are to be pumped, who the generally multi-part locking devices ver applies. Closure devices with a mecha are known African locking of an element such. B. a plug with Rubber O-ring in the locking area. For this purpose, e.g. B. special metal clips or screw connections are used. The different parts of this locking device require egg ne complex construction and assembly (cf. US 4,418,948 A).

Furthermore, closure devices with the ge named features z. B. from US 3,739,460 A. at one of these devices is at least in its edge area elastic, mostly metallic closure element under Deformation of the same by the line in which it expands sliding closure area where it is under part wise cancellation of its deformation and jamming. There are generally considerable forces for this deformation  required to easily damage in the form of Ver scratches on the inner wall of the pipe  lead and also disassembly of the closure element hinder. In addition, sealing problems often occur.

The object of the present invention is to be the closure direction with the characteristics mentioned above train that the assembly of their closure element he is lighter.

This object is achieved with the measures according to claim 1. Accordingly, it should be provided in the closure device that

• - At least the ring-shaped outer area of the closure element mentes from a super elastic properties Shape memory alloy consists of both a Mar tensite phase as well as in an austenite phase is
• - The outer diameter of the closure element on the Inner diameter of the line is matched that the Introduce the closure element into the line the form memory alloy at least partially a shape change in their super-elastic area of the martensite phase moves,

and

• - the extension of the closure area is selected that the shape memory alloy when inserted into this Range in their comparatively harder austenite phase is transferred.

By integrating a ring from a shape memory alloy tion in the closure element can advantageously both radio tion of the closure device, namely sealing and a bracket can be fulfilled by a single component. so probably the production of the closure element with integration the shape memory "sealing ring" and their assembly significantly simplified compared to known embodiments, since this generally only requires one process step at a time  is. It can be so reliable and free achieve inexpensive sealing.

The sealing and locking function is based on a change in shape of the ring made of the shape memory alloy in its super-elastic area. The corresponding property of superelasticity is described, for example, in the book by D. Stöckel [ed.]: "Alloys with shape memory, Ex pert-Verlag, Ehningen (DE), 1988, (see in particular pages 175 to 186 ) In the area of superelasticity, a deforming force is largely constant over a relatively large expansion range, so that the contact pressure does not increase even when the closure element is inserted further into the line. The outer and inner diameter of the ring made of the shape memory alloy are now so can be coordinated with one another so that the deformation of the ring takes place in the super-elastic range, for example, TiNi alloys can be deformed up to 10% super-elastic. In addition, the closure element can be converted into the martensite form with a somewhat higher tensile force in the super-elastic way The area can be reversibly removed from the interior of the line for reuse Corrosion resistance makes shape memory alloys particularly suitable for use as sealing rings.

The closure element of the device according to the invention thus provides a component of high reliability and availability is easy to use and easy to handle level pressure ratios and the given dimensional ratios nisse is to be adjusted. This allows a good seal guarantee.

Advantageous embodiments of the Ver closing device emerge from the subclaims.

The closure element can in particular be a tubular or have disc-shaped central part with an annular  Sealing element made of the shape memory alloy is closed. The central part z. B. made of plastic consist. Corresponding fasteners are inexpensive to create.

Particularly suitable as shape memory alloy for superelas table or pseudo-elastic applications is a Ti-Ni Alloy, optionally at least one more Has alloy component. However, others are also known te shape memory alloys such. B. on CuZn-, CuAl-, FeNi, FeMn, NiMn, NiAl, TiPd base [with or without wide rer component (s)] usable.

Further advantageous refinements of the closure device tion arise from the sub-items not mentioned above sayings.

The invention is described below with reference to the Drawing explained further. Show

the Figs. 1 and 2 diagrams with stress-strain curves of shape memory alloy in a superelastic region,

the stress-strain-temperature diagram fect their Fig. 3 of a shape memory alloy having Einwegef,

elements of which Fig. 4 and 5 show two embodiments of locking,

the Figure 6 is a conduit with a closure element in the assembled state and.

the Fig. 7, this line with the closure element in sealing off state.

Corresponding parts are shown in the drawing provided the same reference numerals.

The closure device according to the invention is intended to be a Ver have closing element, at least in an annular  Outer edge area from a super elastic properties shape memory alloy (also known as "memory metal draws). Such alloys are both in one Martensite phase (also called "α state or phase" or as "Low temperature phase") also referred to as an austenite Phase (also as "β-state or phase" or as "high temperature maturation phase "referred to) can be transferred. Corresponding alloy gen are in the above-mentioned book by D. Stöckel traded (cf. the book mentioned, especially pages 1 to 30, especially pages 15 and 75). Preferred case Suitable alloys are those on CuZn, CuAl, FeNi, FeMn, NiMn, NiAl, NiTi or TiPd based, where each because possibly at least one other component can be alloyed.

For the closure device according to the invention, super elastic properties of shape memory alloys are to be used (cf. the book mentioned, in particular pages 175 to 186). For an explanation of these properties, reference is first made to the diagram in FIG. 1, in which the stress (σ) strain (ε) curve is shown in a simplified manner for a particularly suitable TiNi shape memory alloy in the superelastic range. As can be seen from the course of the curve in this diagram, an alloy that is initially in the relatively hard austenite phase β can be reversibly converted into the softer martensite phase α with only a slight change in the force (or mechanical stress or load) , This reversibility extends in a range up to a theoretical maximum of 10%. In practical examples with complete reverse conversion, this value is around 1.5%. In this area of superelasticity, the respective force is almost constant over a relatively large expansion range during the transition between the phases α ↔ β.

The effect of superelasticity makes use of the fact that in a thermoelastic martensitic transformation, the temperature and the tension are equivalent or interchangeable variables. Therefore, with such a transformation, martensite formation can be caused not only by thermal, but also by mechanical forces. If a shape memory alloy is subjected to a mechanical stress in the high temperature state β (austenite phase), preferred martensite variants arise which, for example, lead to a sample extension in the event of tensile stress. The martensite variants arise and grow with increasing tension, while disappearing in reverse in the event of a decrease in tension. To explain this effect, reference is also made to the stress (σ) strain (ε) curves of the diagram in FIG. 2, which are taken from the aforementioned book by D. Stöckel, page 176. The diagram shows the stress-strain curve at room temperature for a shape memory alloy in the austenite phase β (curve I, dashed) and for a conventional alloy without thermoelastic martensitic transformation (curve II, solid). While the ordinary alloy has an elastic elongation of about 0.2%, the shape memory alloy returns to its original length even after an elongation of 1.5% when the tension is removed. A linear elastic deformation of the austenite phase is followed by a non-linear elastic range, which is due to a stress-induced phase transformation. This behavior is referred to as super elasticity or pseudo elasticity. The illustrated stress-strain curve of the superelastic alloy shows the hysteresis also illustrated in FIG. 1.

The stress (σ) -, deformation (ε) -, temperature (T) diagram shown in Fig. 3 results for a shape memory alloy with a so-called one-way effect (cf. the mentioned book by D. Stöckel, page 2 and pages 64 to 79). In the diagram are marked with
α the martensite phase,
β the austenite phase,
e _1w the relative shape change with one-way effect
R _{P α} , R _t the yield strength of the martensite phase or the beginning of the super elastic deformation
with A _s and A _f the austenite start (α to β) or the auste nit end.

From the diagram is the area of the super elastic effect tes (= area enclosed by the arrowed lines) removable.

Fig. 4 shows a first embodiment of a Verschlussele mentes 2 for an inventive closure device. The closure element contains a tubular or disk-shaped central part 3 a of a plastic stopper 3 . This central part is enclosed by an annular sealing part 4 made of a shape memory alloy with the required superelastic property. This sealing part 4 forms the ring-shaped outer edge region of the closure element.

In contrast to the embodiment according to FIG. 4, the closure element 6 shown in FIG. 5 has only one tubular or disk-shaped central part 3 a, which is not expanded like a cap at one end piece as shown in FIG. 4. On the outside of this central part 3 a sits the sealing ring 4 from the shape memory alloy with an outer diameter R _a .

From Fig. 6, a closure device 7 with a tubular line 8 z. B. from plastic, which serves to promote a gaseous or liquid medium and with the help of a closure element such. B. to be closed according to FIG. 5. The pipeline 8 forms a channel 8 a with an inner diameter R _i , which is widened in a groove or groove-like manner in a closure region 9 . According to the invention, the outer diameter R _{a of} the closure element 6 or its sealing part 4 should be matched to the inner diameter R _{i of} the channel 8 a of the line 8 such that, as shown in the figure, when the closure element 6 is inserted into the channel 8 a the sealing part 4 is deformed from the shape memory alloy such that the deformation according to the diagrams of FIGS . 1 to 3 lies in a superelastic range of the martensite phase. When inserting the Dichtungsele element in the channel 8 a in the direction indicated by an arrow on the direction r then he occurs in the sealing part 4 heightened stresses, which brings the shape memory material super elastic into the softer martensite shape. If the slightly enlarged diameter of the sealing area 9 of the line is reached according to FIG. 7, the associated change in shape of the sealing part 4 causes a transition to the tougher austenite shape to a somewhat larger radius and thus a locking and sealing of the line channel 8 a in this area. The annular sealing part 4 fixed in the plastic central part 3 a thus closes off the conduit in this area and holds the central part a or the entire plug 3 in the conduit. The shape of the groove or groove of the closure region 9 can be selected so that there is a good positive fit between the sealing ring 4 made of the shape memory alloy and a groove wall is ensured. The assembly process is reliable and can be easily checked. When using a Stop fens of FIG. 4 may, for this as a plastic part. B. be constructed so that it locks the line 8 flush after locking.

Deviating from the illustrated embodiments of the closure element 2 or 6 , this can also have a differently shaped central part 3 a, which can also consist of a material other than a plastic material. Of course, the closure element can also be made entirely of a shape memory alloy. The only essential thing is that its outer edge area has superelastic properties and the diameters R _{i of} the conduit channels 8 a and R _{a of} the closure element are matched to one another in such a way that the desired transition from the softer martensite phase to the harder austenite phase is caused by the diameter expansion in the closure area.

Claims (5)

1. Closure device of a tubular line for the promotion of a gaseous or liquid medium, which has a predetermined inner diameter, which is expanded in a sealing region or groove-like manner, with a closure element, which
in an assembled state has an enlarged outer diameter compared to the inner diameter of the line,
is designed to be elastic at least in an annular outer edge region and
can be inserted into the sealing area of the line, where jamming occurs,
characterized in that

• a) at least the annular outer edge region of the closure element ( 2 , 6 ) consists of a shape-memory alloy which shows superelastic properties and which can be converted into a martensite phase as well as an austenite phase,
• b) the outer diameter (R _a ) of the closure element ( 2 , 6 ) is tuned to the inside diameter (R _i ) of the line ( 8 ) in such a way that when the closure element is inserted into the line, the shape memory alloy at least partially changes shape in its superelastic Area of the martensite phase,

and

• a) the expansion of the closure area ( 9 ) is selected such that the shape memory alloy is transferred into its comparatively harder austenite phase when it is introduced into this area.

2. Closure device according to claim 1, characterized in that the closure element ( 2 , 6 ) has a tubular or disc-shaped central part ( 3 a) which is enclosed with an annular sealing part ( 4 ) made of the shape memory alloy. 3. Closure device according to claim 2, characterized in that the central part ( 3 a) consists of plastic. 4. Closure device according to one of the preceding claims, characterized in that the tubular line ( 8 ) is made of plastic or metal. 5. Closure device according to one of the preceding claims che, characterized in that the shape memory alloy is a CuZn or CuAl or FeNi or FeMn or NiMn or NiAl or TiPd or preferably is a TiNi alloy, which may still be at least has another alloy component.