DE102009030153A1 - Probe base for protecting U-shaped end piece of geothermal probe, has base body accommodating U-shaped end piece, and spacer including pipelines that exist from end piece at distance to each other and force-fittingly connected with body - Google Patents

Abstract

The base has a base body (1) accommodating a U-shaped end piece, and a spacer including pipelines that exist from the end piece at a distance to each other. The spacer is force-fittingly connected with the base body, which includes an opening (5), where the end piece in interposed in the opening. A closing head (6) lies opposite to the opening in an insertion direction, and the spacer is introduced in the opening, where the closing head is made up of reinforced and/or hardened material. The base body and the spacer are made up of metal and/or plastic material.

Description

The The invention relates to a probe foot, which U-shaped End pieces of geothermal probes bored in boreholes are to be admitted.

Before the production of geothermal probes a hole is drilled first, which may have a depth of several tens of meters to several hundred meters. In this hole then the geothermal probe is lowered. A geothermal probe consists in principle of two pipes, which are connected at its lower end, with which they are let into the well, by means of a U-shaped end piece, also referred to as probe end. The spaces between the pipes and the borehole are pressed with special grout. Through the U-shaped pipes, a heat transfer medium is pumped during operation, usually brine, for example, water-ethylene glycol solutions or water-salt solutions. As an alternative, CO ₂ and ammonia are also suitable as heat transfer media. During operation, heat is absorbed from the soil via the surface of the pipes or heat is released to the ground.

A critical issue in the manufacture and installation of geothermal probes is regularly the lowering of the associated with the U-shaped end pipe into the well. As the holes usually have no smooth inner wall in the ground, but it a variety more or less pronounced Rock projections and clefts are, it can happen that when inserting the geothermal probe into the ground, the probe tip touches one of these projections, gets stuck or even abuts. In any case, this can result in damage to the U-shaped tail which, if not immediately noticed, can affect the long-term stability of the borehole heat exchanger and even lead to its failure, even if prescribed pressure samples should give a correct result. For this reason, it is attempted to stabilize the U-shaped end pieces on the one hand by constructive measures, for example by the two legs of the U of the tail are connected to each other with the same material from which the tail is made, so that the rigidity of the in the Usually one-piece made of special plastic or metal-made tail is increased. Another possibility is to provide at the lower end of the U-shaped end piece an area to which an additional weight can be attached. This, compared to the thickness of the U-shaped tube narrow areas at the apex of the "U" can be made in the production of plastic end pieces by appropriate design of the forms also with the tail of one piece. Compared to the vertex of the "U" these areas then usually have a hole in which a weight can be hung. These additional weights are usually not rigidly connected to the tail, but this can relative to perform relative movements and swing. When you let the probe into the ground there is also the danger that such a weight gets stuck on a projection or fissures of the well, so that the geothermal probe must be pulled up a piece again until the weight floats again, and again you must try to lower the probe. This method is time consuming, also the probe end piece is also not particularly protected. Probe end pieces, which are designed according to this principle, are for example in the DE 202 02 578 U1 , in the DE 10 2007 036 324 A1 and in the CH 687268 A5 described.

Another possibility is to surround the U-shaped end piece with a protective jacket which can absorb impacts. Such a protective jacket is for example in the DE 20 2005 004 815 U1 described. This is materially connected to the tail and thus not reversibly solvable. When attaching additional weights, however, there would be a risk that this protective jacket breaks. All in all, the solutions currently known in the art are therefore unsatisfactory.

The Object of the present invention is that mentioned Disadvantages of the prior art to eliminate, in particular a Probe foot to develop which the tails Reliable against damage caused by the impact on protrusions or fractures in boreholes protects and on the other hand also the possibility offers to flexibly use extra weights if this should be required, with the probe foot reversible to be connected to the U-shaped tail, in case of any problems with a construction easy access to get to the probe end piece and replace it if necessary to be able to.

This object is achieved with a probe foot of the type described above in that such a probe foot comprises a base body which receives at least one end piece and a spacer, which pipes, which depart from the end piece, holds at a distance to each other, wherein the spacer frictionally with the Basic body is connected. Due to the purely non-positive connection of the spacer, which keeps the pipes at a distance and can also be used to fix the pipes or the probe end in the body, a simple handling and easy separation is possible. Such a frictional connection can, for example carried out in the manner of a bolt whose circumference is in registration with respect to the bore into which it is to be introduced, wherein the bore is made in relation to the circumference of the bolt according to a slight interference fit, so that a connection between the bolt and bore only can be made with additional pressure. By mechanical force, for example, by appropriate blows with a hammer, this compound is produced and also solvable again, the probe end piece can therefore be removed again, if necessary, from the body. In addition, positive, re-releasable connections between spacers and body are conceivable or combinations of positive and non-positive connections.

In In a preferred embodiment, the base body has an opening on, in which the at least one tail are inserted can, and a closure head, that of the opening in the insertion direction opposite. This way will the U-shaped tail of five spatial directions - just above, contrary to the feed direction when the probe is introduced into the soil, not - against impacts from outside protected, the end cap also reinforced and / or may consist of hardened material. Of the Spacer is then in the connected state in the upper opening of the Introduced body. Base and spacers can be made of different materials such as Be made of plastic or metal, with metal - for example an aluminum alloy - compared to the use Of plastic has the advantage that it is a higher has specific weight, so that the main body made of metal has a higher mass than a main body made of plastic. In some cases, for example dispensed with the use of an additional weight become.

Prefers the body is made in one piece, this offers highest stability against mechanical External effects and also reduces manufacturing costs. The basic body must be able to at least take a tail, for cost reasons and because more than one probe is often used, the Basic body in a preferred version, however designed so that it has two end pieces with parallel accommodating mutually lying U-shapes. Alternatively, the main body also be designed so that it is an end piece with four intersecting pipelines. Also the recording additional probe end pieces and the combination of simultaneous recording Different shaped end pieces is possible, provided this should be required.

The Form of the basic body can basically be arbitrary can be selected, for example, the main body be configured cuboid. The fewer corners and edges the main body has, the lower is however the risk of being placed or caught by tilting in the Borehole. Ideal would be the use of a spherical shape or a form similar to that, but usually at the Narrow holes fail. In a particularly preferred Embodiment, the base body with the shape of a hollow cylinder with a lateral surface, a top and a bottom on. The main body has an opening at its top on, so that the at least one tail along the longitudinal axis of the hollow cylinder inserted into this can be. On its underside, the base body a closure head with an inner and an outer Closing surface on. The outer one The finish can be like the base of a Be shaped cylinder, so flat; because this area at Admitting the geothermal probe with the main body However, pointing downwards, it is beneficial to the angles of the Edges between outer surface and lateral surface as large as possible to choose. This can be done, for example, by the main body between outer end surface and The outer surface of the cylinder is chamfered or is rounded. Alternatively, the outer end surface also according to an outward arched and in relation to the lowest point - the outer one End face facing down - flattened Hemisphere be configured. All forms in between are possible Furthermore, conical shapes are with flattened cone point or rounded Cone tip also a possible alternative.

Independently from the outer shape, it is advantageous if the main body has a cylindrical inner wall having, with bulges for conditioning the at least one End piece and the outgoing piping provided where the spacer is the piping in the bulges fixed. As well as a cylindrical body very easy to make essentially by turning, so applies the same for a cylindrical Interior wall. The production costs are the lowest here. By doing the inner wall has bulges, to which the pipes and the tail can be created, found in the body already by the introduction of the end pieces a prefix instead, the final fixing takes place by means of the spacer. After this frictionally with the body was connected, the pipes are fixed in the bulges, so that ensures a high stability becomes.

The stable storage of the U-shaped end pieces in the base body is further improved when the inner end surface of the end cap has at least one groove corresponding to the number of male end pieces to accommodate two the end pieces so two grooves. In the groove, a corresponding area can then be introduced at the lower end of the tail. This lower region corresponds to the region in conventional plastic probe end pieces, which is designed to hang the weights there. So he usually already has a hole for attaching these weights. The use of differently shaped probe end pieces is possible, the groove can then be dispensed with. The groove can be configured continuously from the inner end surface to the outer end surface, so that it penetrates the outer end surface. This allows for a better access to the areas at the lower end of the end pieces. On the other hand, the concrete that is used in the backfilling geothermal probes, then penetrate the grooves, so that a higher fixation is achieved in terms of long-term stability.

In Another preferred embodiment of the invention is in the End cap at least one cutting the at least one groove Introduced bore. Indicates the probe end in the area at lower end a hole of appropriate size for attachment extra weights on, so the hole is to be aligned, that they - with inserted tail with the hole on a line. Then one with oversize fit Inserted precisely made bolt inserted into the bore become. The bolt must then by mechanical pressure be introduced into the bore. Is the bolt in the hole brought in, he also punctures the hole accordingly Size in the area at the lower end of the tail and additionally fixes the U-shaped end piece to the spacer, with respect to the opening of the Basic body also with oversize fit made to fit. The bolt is then with the main body positively connected, the tail is by means the bolt frictionally and positively with the body connected and fixed in this.

In a further preferred embodiment of the invention, the End cap along the longitudinal axis of the body - at a cylindrical base body centered - a Longitudinal bore from the outer end surface inside, preferably the inner end surface piercing, on. Such a longitudinal bore can fulfill several purposes. For one thing, it can be with one Diameter be executed that, if one Groove and a groove intersecting bore are present, this hole pierces the wall of the longitudinal bore. This makes it possible to the bolts in a simple way should this be necessary. Alternatively or in addition but the longitudinal bore can also be designed so that they has an internal thread. This allows the attachment other elements such as additional weights on the body.

In a further preferred embodiment of the invention the probe foot therefore at least one intermediate body, which positively and / or non-positively connected to the body is. Leaves a positive connection For example, when the body in the longitudinal bore has an internal thread. The at least an intermediate body has in this case an external thread on, which in the internal thread in the end cap of the Body is screwed. The intermediate body claimed in the borehole connection only on train. To more To use intermediate body, lies the external thread along the longitudinal axis of the thread appropriate an internal thread opposite. Is the intermediate body, for example designed as a solid solid cylinder, the external thread Preferably on the top surface and the internal thread on the Base of the cylinder attached.

In a further preferred embodiment of the invention the probe foot also has an end body, which positive and / or non-positive with the body or the intermediate body is connected. For the production a positive connection, the end body For example, have an external thread, which in the Internal thread in the end cap of the main body or screwed in the intermediate body.

There the end body usually the lowest element of the probe foot is preferred, it is preferred as a solid cylinder with a top surface, on which the external thread is arranged, designed and has a base, wherein the end body between base and lateral surface with a Bevel provided or rounded or the base area accordingly an outwardly arched hemisphere configured is, whereby also all intermediate forms are possible. The most extensive Avoiding edges reduces the risk of getting stuck Borehole to a large extent.

After all is in a further embodiment, the spacer equipped with an internal thread into which, for example, a push-in rod can be screwed, which is the introduction of the geothermal probe additionally supported by downward pressure.

It it is understood that the above and the following yet to be explained features not only in the specified Combinations, but also in other combinations or in isolation can be used without departing from the scope of the present invention.

Hereinafter, the invention beispielswei se with reference to the accompanying drawings, which also disclose features essential to the invention, explained in more detail. Show it:

1a -B different views of a main body of a probe foot,

2a -C views of a spacer of a probe foot,

3a a view of a probe foot with U-shaped tail,

3b a cross section through this ensemble,

4 an intermediate body for a probe foot and

5 an end body for a probe foot.

In 1a is initially the cross section through a body 1 a probe foot which protects U-shaped end pieces of borehole heat exchangers to be inserted in boreholes. Such a basic body 1 takes at least one such tail, in the example shown is the body 1 designed to accommodate two U-shaped end pieces, wherein the U-shapes of both end pieces are parallel to each other.

In the example shown, the main body 1 the shape of a hollow cylinder, with a lateral surface 2 , a top 3 and a bottom 4 , At its top 3 indicates the basic body 1 an opening 5 on, so that the at least one end piece along the longitudinal axis of the cylinder can be inserted into this. At its bottom 4 indicates the basic body 1 a graduation head 6 with an inner closure surface 7 and an outer end surface 8th on. In the example, the transition between lateral surface 2 and outer closure surface 8th without sharp edge, the outer end surface 8th corresponds to an outwardly curved hemisphere which is strongly flattened with respect to the lowest point. Alternatively, the outer end surface 8th , which corresponds to the base of the cylinder, also be designed flat with rounded edges with respect to the lateral surface 2 , Also, the attachment of a simple chamfer between lateral surface 2 and outer closure surface 8th is a possibility. The main body 1 is made in one piece, the end cap 6 reinforced, ie made thicker, and / or can also be made of hardened material, for example by the surface of the outer end surface 8th was subjected to a separate treatment. The main body 1 the probe foot also has a cylindrical inner wall 9 on top, with bulges 10 provided for the installation of the end pieces and the outgoing piping. In the area of the opening 5 indicates the basic body 1 on the inner circumference a circumferential, only through the bulges 10 broken edge 11 on, you will find this counterpart in the following with reference to 2 explained spacers 12 ; it serves to prevent the spacer 12 too deep in the body 1 penetrates.

Different views of a spacer 12 are in the 2a - 2c shown. In 2a is the spacer 12 shown from above in 2c from below, in 2 B an isometric perspective view is shown. The corresponding counterpart to the edge 11 in the main body 1 here forms the edge 13 at contact surfaces fourteen of the cross-shaped spacer 12 , The spacer 12 is in the connected state in the upper opening 5 of the basic body 1 introduced, it holds on the one hand the pipes that go off the U-shaped end pieces, at a distance from each other and fixed to the other these pipes in the bulges 10 of the basic body 1 , In the inserted state is the spacer 12 non-positively with the body 1 connected. The frictional connection takes place via the outer contact surfaces fourteen , These are the contact surfaces fourteen In register with slight interference fit with respect to the inner wall 9 of the basic body 1 made so that there is no play and pressure must be spent to the spacer 12 with the main body 1 to connect non-positively. An additional fixation is then usually not necessary, it only requires mechanical force to the spacer 12 in the opening 5 of the basic body 1 to fix and also to get him back from the main body 1 to remove.

spacer 12 and basic body 1 can be made of plastic, but a production of metal is preferable because both parts can then be rotated, for which the same machine can be used, which greatly simplifies the production of fitting parts. In addition, metal has the advantage of a higher specific weight, which leads to a higher mass with the same dimensions; this is advantageous when introducing the probe foot into a borehole.

As in 1a shown has the inner end surface 7 at least one groove 15 according to the number of end pieces to be picked up, in this case two grooves 15 , A corresponding area at the lower end of an end piece can be inserted into this groove. This lower portion of the tail is typically used to attach additional weights there to facilitate insertion of the probe into the wellbore. The grooves 15 are consistent throughout to the outer surface 8th designed, they pierce these. This is not absolutely necessary, but also facilitates the production. In the graduation head 6 is for each groove 15 one the respective groove 15 - In the example at an angle of 90 ° in both plan view and in longitudinal section - cutting bore 16 brought in. If the end pieces are inserted, so will through these holes 16 a precise fit with interference fit bolt introduced, which also pierces a hole of appropriate size in the region at the lower end of the tail. Due to the precise fit of the bolt this is held solely by frictional forces in the bore, so that the bolt frictionally with the body 1 connected and the tail by means of the bolt form-fitting with the body 1 connected is.

In addition, the termination head 6 along the longitudinal axis of the body 1 - centered here - a longitudinal bore 17 on, from the outer end surface 8th inside, with the inner end surface 7 can be pierced. The grooves 15 cutting holes 16 also pierce the wall of the longitudinal bore 17 , which facilitates removal of the bolts, if necessary. The longitudinal bore 17 may also have an internal thread, not shown.

In 3a in perspective and in 3b in cross-section is once again the ensemble of main body 1 and spacers 12 shown, but here already an end piece 18 into the main body 1 is used, from which pipelines 19 depart. The tail 18 has a lower area here 20 with a hole. About the hole 16 is a bolt 21 driven through this hole and fixes the tail 18 positively with the body 1 , The bolt 21 itself is with the main body 1 positively connected, as already described above. The spacer 12 also has recesses 22 on, which have corresponding upper areas 23 of the tail 18 To stabilize the U-shape of the tail 18 serve, can be slipped and provide extra stability. The spacer 12 Also has a hole on its top 24 , which can also have an internal thread into which a slide-in rod can be screwed. The probe foot can then be pushed into the borehole with the aid of the insertion linkage.

Although the probe foot has in its basic form with the main body 1 and the spacer 12 even a not too small weight, especially if the probe foot is made of metal; However, this dead weight is sometimes not sufficient to ensure a smooth insertion into the wellbore. The probe foot can therefore also have one or more intermediate bodies in a modular design 25 include, which is positively and / or non-positively connected to the body. One to the in 1 illustrated basic body 1 matching intermediate body 25 is in 4 shown. He is designed here as a solid cylinder and has a top surface 26 on, on an external thread 27 is arranged. For attaching further weights may be on the base 28 the cylinder a corresponding internal thread, which is not shown here, be arranged. Also the intermediate body 25 is preferably made of one piece, the edges between the lateral surface and the base or top surface ( 26 . 28 ) of the cylinder may also be rounded. In the present example, they are provided with a chamfer. To ensure a compact construction, the intermediate bodies 25 preferably of metal, for example of steel. The intermediate bodies can be provided in various sizes or masses, for example in the masses of 25, 40, 60 and 90 kg. With the external thread 27 becomes the intermediate body 25 in the internal thread 17 of the basic body 1 screwed and thus positively connected with this.

In addition, the probe foot can still have an end body 29 include, such, to the main body 1 matching end body 29 is for example in 5 shown. The end body 29 is analogous positive and / or non-positive with the body 1 or the intermediate body 25 connected. For this purpose, the end body 29 an external thread 30 on, which in the internal thread of the intermediate body 25 or the internal thread 17 of the basic body 1 is screwed. In this way, a positive connection between the elements is made. The in 5 shown end body 29 is also a solid cylinder with a top surface 31 designed, on which the external thread 30 is arranged. Accordingly, the end body 29 on the top surface 31 be provided with a base surface opposite side, in which case the edge between the base surface and lateral surface can be provided with a chamfer or rounded. In the present example, however, the base is corresponding to an outwardly curved hemisphere 32 designed. This hemisphere 32 can also be flattened, other geometric shapes or cones with rounded tip are conceivable embodiments.

The probe foot described above can thus be provided with additional weights in a modular manner, depending on the requirements that prevail on the construction site. It is also possible to replace or supplement a weight spontaneously if the weight used up to that point is too small. The described probe foot provides a high level of protection when introducing the geothermal probe into the borehole, the U-shaped end piece 18 The geothermal probe - usually made of polyethylene - is positively and non-positively enclosed by the probe foot. The probe base is compact and offers due to its rounded shapes good gliding properties. In the spacer 12 a threaded receptacle is integrated, so that a slide-in rod can be used easily. Individually necessary weights are easy to screw on. The reinforced and rounded bottom of the main body 1 or the end body 29 provides additional impact protection and provided the body 1 Made of metal, it also offers a higher thermal conductivity compared to the otherwise used plastic.

LIST OF REFERENCE NUMBERS

1

body

2

lateral surface

3

top

4

bottom

5

opening

6

Closing head

7

internal end surface

8th

outer end surface

9

inner wall

10

bulge

11

edge

12

spacer

13

edge

14

contact area

15

groove

16

drilling

17

longitudinal bore

18

tail

19

pipeline

20

lower Area

21

bolt

22

recess

23

upper Area

24

drilling

25

intermediate body

26

cover surface

27

external thread

28

Floor space

29

end body

30

external thread

31

cover surface

32

hemisphere

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 20202578 U1 [0003]
• - DE 102007036324 A1 [0003]
• CH 687268 A5 [0003]
• DE 202005004815 U1 [0004]

Claims (22)

Probe foot, which U-shaped end pieces ( 18 ) protects from borehole borehole geothermal probes, comprising - a base body ( 1 ), which has at least one tail ( 18 ), and - a spacer ( 12 ), which pipelines ( 19 ) coming from the tail ( 18 ), keeps at a distance to each other, and which non-positively with the body ( 1 ) connected is. Probe foot according to claim 1, characterized in that the basic body ( 1 ) an opening ( 5 ) into which the at least one end piece ( 18 ) and a header ( 6 ), the opening ( 5 ) in the insertion direction opposite. Probe foot according to claim 2, characterized in that the spacer ( 12 ) in the opening ( 5 ) is introduced. Probe foot according to one of claims 2 or 3, characterized in that the termination head ( 6 ) is reinforced and / or made of hardened material. Probe foot according to one of claims 1 to 4, characterized in that the basic body ( 1 ) and the spacer ( 12 ) are made of metal and / or plastic. Probe foot according to one of claims 1 to 5, characterized in that the basic body ( 1 ) is made in one piece. Probe foot according to one of claims 1 to 6, characterized in that the basic body ( 1 ) two end pieces ( 18 ) receives parallel to each other U-shapes. Probe foot according to one of claims 1 to 7, characterized in that the basic body ( 1 ) the shape of a hollow cylinder with a lateral surface ( 2 ), a top and a bottom ( 3 . 4 ), wherein the basic body ( 1 ) on its upper side ( 3 ) an opening ( 5 ), so that the at least one end piece ( 18 ) can be inserted along the longitudinal axis of the cylinder in this, and wherein the base body ( 1 ) on its underside ( 4 ) with a termination head ( 6 ) with an inner and an outer end surface ( 7 . 8th ), the base body ( 1 ) between outer end surface ( 8th ) and lateral surface ( 2 ) of the cylinder is chamfered or rounded, or wherein the outer end surface ( 8th ) is configured according to an outwardly arched and flattened in relation to the lowest point hemisphere. Probe foot according to one of claims 1 to 8, characterized in that the basic body ( 1 ) a cylindrical inner wall ( 9 ) with bulges ( 10 ) for the installation of the at least one end piece ( 18 ) and the outgoing pipelines ( 19 ), wherein the spacer ( 12 ) the pipelines ( 19 ) in the bulges ( 10 ) fixed. Probe foot according to one of claims 8 or 9, characterized in that the inner end surface ( 7 ) at least one groove ( 15 ) according to the number of end pieces ( 18 ) into which a corresponding area ( 20 ) at the lower end of the at least one end piece ( 18 ) can be introduced. Probe foot according to claim 10, characterized in that the at least one groove ( 15 ) continuously to the outer end surface ( 8th ) is configured and this pierces. Probe foot according to claim 10 or 11, characterized in that in the closure head ( 6 ) at least one the at least one groove ( 15 ) cutting hole ( 16 ) is inserted into which a bolt ( 21 ), which is a hole of corresponding size in the area ( 20 ) at the lower end of the tail ( 18 ) penetrates the bolt ( 21 ) with the basic body ( 1 ) frictionally and the tail ( 18 ) by means of the bolt ( 21 ) with the basic body ( 1 ) connected is. Probe foot according to one of claims 8 to 12, characterized in that the closure head ( 6 ) along a longitudinal axis of the body ( 1 ) a longitudinal bore ( 17 ) from the outer end surface ( 8th ) inward, preferably the inner end surface ( 7 ) piercing. Probe foot according to claim 13, when dependent on claim 12, characterized in that the groove ( 15 ) cutting hole ( 16 ) the wall of the longitudinal bore ( 17 ) pierces. Probe foot according to claim 13 or 14, characterized in that the longitudinal bore ( 17 ) has an internal thread. Probe foot according to one of claims 1 to 15, further comprising at least one intermediate body ( 25 ), which positively and / or non-positively with the main body ( 1 ) connected is. Probe foot according to claim 16, when dependent on claim 15, characterized in that the at least one intermediate body ( 25 ) an external thread ( 27 ), which in the internal thread in the end cap ( 6 ) of the basic body ( 1 ) and one along the longitudinal axis of the external thread ( 27 ) this opposite In nengewinde. Probe foot according to claim 17, characterized in that the intermediate body ( 25 ) is designed as a solid cylinder, with an external thread ( 27 ) on the top surface ( 26 ) and an internal thread on the base ( 28 ), Probe foot according to one of claims 1 to 18, further comprising an end body ( 29 ), which positively and / or non-positively with the main body ( 1 ) or the intermediate body ( 25 ) connected is. Probe foot according to claim 19, when appended to one of claims 15, 17 or 18, characterized in that the end body ( 29 ) an external thread ( 30 ), which in the internal thread in the end cap ( 6 ) of the basic body ( 1 ) or in the intermediate body ( 25 ) is screwed. Probe foot according to claim 20, characterized in that the end body ( 29 ) as a solid cylinder with a top surface ( 31 ) on which the external thread ( 30 ) is arranged, and a base surface is provided, wherein the end body ( 29 ) is provided with a chamfer between the base surface and lateral surface or is rounded off, or wherein the base surface corresponding to an outwardly curved hemisphere ( 32 ) is configured. Probe foot according to one of claims 1 to 21, characterized in that the spacer ( 12 ) a hole ( 24 ) having an internal thread into which a slide-in rod can be screwed.

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