Extendable ruler

Abstract

The present invention relates to an extendable multi-link measuring stick (1) constructed of a plurality of measuring links (2) disposed one on top of the other, the individual measuring links (2) being connected to one another by means of a tongue-and-groove joint. The top side (3) of the topmost measuring link (2) and the bottom side (4) of the bottommost measuring link (2) each have a smooth surface. The middle measuring links (2) disposed between the outer measuring links (2) each have, on their top sides (3), a groove which widens towards the inside, while a corresponding tongue (7) extending in the longitudinal direction is disposed on the bottom sides (4). The tongue (7) comprises a tongue groove (9) for the arranging and receiving of locking elements.

Description

[0001] Extendable folding rule

[0002] TECHNICAL FIELD

[0003] The present invention relates to an extendable folding rule which is intended to be used as a faster and more convenient alternative to the foldable folding rule, wherein the extendable folding rule is also intended in particular as a niche measuring stick.

[0004] STATE OF THE ART

[0005] Folding rules and other simple measuring instruments are still indispensable basic equipment in trades and construction today. They allow for the quick inspection of components or the precise measurement of lengths, widths, heights, and distances. The most well-known measuring instrument is the folding rule, a folding measuring device with two measuring edges, typically used for lengths of up to two meters. Rulers, tape measures, and straightedges are also used as simple tools.

[0006] One disadvantage of the folding or unfolding ruler is that users often find unfolding the ruler annoying, time-consuming, and cumbersome. Furthermore, the folding ruler is prone to breaking at the hinge if used carelessly or improperly, rendering the ruler useless.

[0007] As an alternative to a folding ruler, a tape measure, usually a flexible, roll-up tape made of steel, coated canvas, or plastic, can be used for quick measurements. While this prevents the measuring tool from breaking, the handling of the tape measure, when used by one person, only allows measurements corresponding to approximately twice the person's arm length, making it unsuitable for many measuring operations, especially in the trades.

[0008] DE TI 19 512 A1 describes an extendable niche measuring rod, designed like a car antenna and telescopically, that allows niches to be measured in a single step. A new type of sequential numbering is used, allowing the niche spacing to be read precisely in the center of the measuring rod.

[0009] The subject of utility model DE 20 2006 013 035 Ul is a telescopic folding rule comprising several telescopically connected tubes of rectangular or other cross-sections, with the tube with the larger cross-section having an observation window for viewing a scale. The telescopic folding rule is intended particularly for measuring niches or internal dimensions.

[0010] Telescopic measuring rods, which usually work with smaller, telescopic tubes as measuring elements, often have the disadvantage that measurement inaccuracies can occur if the tubes are pulled apart incompletely or not in the correct order.

[0011] We also offer wooden folding rules with extendable brass tongues for internal measurements. The top section of the fold-out wooden folding rule has an extendable brass tongue integrated into it, which can then be used to carry out internal measurements.

[0012] DT 26 01 240 A1 discloses a folding rule in which each measuring element is designed as a metallic hollow profile with a trapezoidal cross-section, the longer trapezoidal side of which has a continuous longitudinal slot, while the shorter trapezoidal side of which carries two outwardly inclined guide rails and all measuring elements, when pushed into one another, engage with their longitudinal slot over the guide rails of the adjacent measuring element.

[0013] Based on this prior art, the objective of the present application is to offer an extendable folding rule or folding ruler that offers advantages over the prior art and is easy and safe to handle, making it an improved alternative to the conventional folding ruler. The folding ruler can also be used as a niche ruler. A further advantage over conventional folding rulers is that the measuring elements can no longer collapse when measuring sideways, allowing the user to easily measure a length corresponding to the length of the ruler with the folding ruler according to the invention, even with an outstretched arm.

[0014] PRESENTATION OF THE INVENTION

[0015] The object is achieved by a folding measuring stick according to claim 1. Further possible embodiments of the invention are specified in particular in the dependent claims.

[0016] The inventive solution consists of an extendable measuring rod made up of several measuring elements arranged one above the other, with the individual measuring elements being connected to one another via a tongue and groove connection.

[0017] The uppermost measuring element has a smooth upper surface and a longitudinally extending, outwardly widening groove on its underside. In contrast, the lowermost measuring element has a smooth underside and a longitudinally extending, inwardly widening groove on its upper surface.

[0018] The middle measuring elements arranged between the two outer measuring elements each have a groove on their upper sides extending in the longitudinal direction and widening inwards, and on their lower sides each have a tongue extending in the longitudinal direction and widening outwards.

[0019] The bungs and the grooves are designed as a connection between the measuring elements and at the same time as a guide for pulling the folding measuring rod apart and together, wherein additional bung grooves extending in the longitudinal direction are arranged in the bungs for the arrangement and reception of locking elements, wherein the measuring elements have locking elements matched to one another in pairs and provided for locking and fixing the measuring elements in the fully extended and fully pushed together state.

[0020] To prevent the individual measuring elements from separating when the folding measuring rod is pulled apart, an advantageous embodiment provides a flat receiving area on the underside of each measuring element for a stop bar of the underlying measuring element. Thus, the uppermost measuring element has a smooth upper surface and, on its underside, a continuous, outwardly expanding bung extending longitudinally from a flat receiving area for a stop bar of the underlying measuring element to the end of the measuring element.

[0021] In contrast, the lowest measuring element has a smooth underside and on its upper side a groove extending from a stop bar to the end of the measuring element and widening inwards.

[0022] The middle measuring elements arranged between the two outer measuring elements each have on their upper side a groove extending from a stop web to the end of the measuring element and widening inwards, and on their undersides each have a bung extending from a flat receiving area for a stop web of the measuring element below to the end of the measuring element and widening outwards.

[0023] In an advantageous embodiment of the present invention, the locking elements provided in the bung grooves comprise convexities located opposite one another on both sides and projecting into the interior of the bung groove in the front area of ​​the bung groove which is open and visible when the measuring elements are pulled apart.

[0024] Preferably, this arrangement of the locking elements is combined with additional curvatures, which also protrude on both sides, in the rear region of the bung groove lying in the pull-out direction, wherein the additional curvatures are combined with stop elements arranged on both sides and perpendicular to the pull-out direction, which have a stop surface oriented perpendicular to the pull-out direction.

[0025] Advantageously, the locking elements in the bung grooves interact with at least one corresponding locking element of an adjacent measuring element arranged in the inwardly widening grooves. The locking elements are designed to lock and secure the measuring elements in the fully extended and retracted states.A preferred embodiment of the present measuring rod provides that the at least one corresponding locking element of the adjacent measuring element, which is arranged in the inwardly widening grooves, is a free-standing isosceles prism, wherein the prism is arranged centrally in the rear region of the groove lying in the extension direction, wherein the tip of the prism formed by the equal legs points in the extension direction and the locking elements are coordinated with one another in such a way that the flat rear side of the prism rests against the stop surfaces of the stop elements when the measuring element is completely pulled out and thus the prism locks between the stop elements and the curvatures.

[0026] The subject of an alternative embodiment is a folding measuring rod according to the invention, in which the locking elements comprise at least one permanent magnet integrated in a measuring element, wherein, for example, a larger permanent magnet is firmly seated in a bore in the inwardly widening groove and projects beyond the bottom thereof into the front region of the bung groove of the adjacent measuring element, while a second smaller permanent magnet is flush with a bore in the bung groove, wherein the permanent magnets are arranged such that the larger permanent magnet comes to stand above the smaller permanent magnet after the measuring element has been pulled out and is fixed there due to the magnetic forces.

[0027] The above-described embodiment of the present invention can be realized with stop webs and the corresponding receiving areas provided for them, but preferably in the above-described alternative embodiment with permanent magnets as locking elements, the bung groove is delimited at both ends by holding webs, wherein the two permanent magnets are arranged in the immediate vicinity of the holding webs, so that when the measuring element is pulled out, the larger permanent magnet projecting into the bung groove is stopped by the holding web adjacent to the smaller permanent magnet, thus preventing unintentional removal of the measuring element in question from the folding measuring rod.

[0028] Thus, in this particularly advantageous and simultaneously simplified alternative embodiment of the present invention, the measuring elements do not have the stop bars and the corresponding receiving areas for the stop bars. Instead, separation of the measuring elements when the measuring rod is pulled apart is prevented, and the cohesion of the measuring rod when the measuring elements are pulled apart is ensured by the fact that the ends of the bung grooves are delimited by retaining bars, which serve as stops for the locking elements engaging in the bung grooves.

[0029] Analogous arrangements with alternative magnetic or mechanical locking elements are described below, whereby the ends of the bungs are also each limited by retaining webs.

[0030] In a particularly preferred embodiment of the present invention, the retaining webs defining the bung groove also function as a locking element. One example of this is a concavely shaped permanent magnet designed as a retaining web at the end of the bung groove, which interacts with a magnetizable counterpart serving as a locking element in the groove of the adjacent measuring element. When the measuring element is fully extended, the magnetizable counterpart is pushed positively into the concavely shaped receiving area of ​​the permanent magnet and secured there by the magnetic force.

[0031] The embodiment described above can of course also be realized if, conversely, the holding web designed as a locking element is magnetizable and the counterpart in the groove of the adjacent measuring element is a permanent magnet or if both locking elements that are operatively connected to one another are permanent magnets.

[0032] Mechanical locking elements can also be used according to the same principle, for example if the holding bar is combined with a clamp as a locking element, into which a cylinder arranged in the groove of the adjacent measuring element then locks as a locking element counterpart.

[0033] Preferably, the tongue and groove joint is a dovetail joint. The outwardly widening tongues are dovetail-shaped, while the corresponding inwardly widening grooves are trapezoidal. A further advantageous embodiment of the present invention provides for the tongue and groove joint to be T-shaped, with the outwardly widening tongues being T-shaped and the corresponding inwardly widening grooves being inverted T-shaped.

[0034] It will be obvious to those skilled in the art that, based on the inventive principle presented, many other locking element combinations can be used to implement the inventive idea. However, further combinations will not be presented in detail within the scope of this description. It should simply be noted that the inventive concept consists in the locking elements being arranged in a designated bung groove or projecting into it, where they are operatively connected to one another to ensure the function of the extendable folding rule.

[0035] The proposed extendable folding rule is explained in detail below using selected examples and drawings. It goes without saying that these examples are by no means limiting, but merely serve to explain the basic principle of the present invention.

[0036] DESCRIPTION OF THE DRAWINGS

[0037] The various exemplary features described above can be combined with one another according to the invention, as long as this is technically feasible. Further features, advantages, and embodiments of the invention will become apparent from the following description of the figures.

[0038] The figures used for explanation show:

[0039] Figure 1 is a perspective view of a partially unfolded folding measuring rod in a top view together with an exemplary individual measuring element to be placed inside the measuring rod package from the same perspective,

[0040] Figure 2 is a perspective view of a partially unfolded folding measuring rod in a view from below together with an exemplary individual measuring element to be arranged inside the measuring rod package from the same perspective,

[0041] Figure 3 shows a cross-section along the section plane S1-S2 of Figure 1,

[0042] Figure 4 shows a horizontal longitudinal section along the plane S3 of Figure 3,

[0043] Figure 5 is an interrupted perspective instruction drawing with two central measuring elements,

[0044] Figure 6 Sectional drawings along the planes S4-S5 and S6-S7 from Figure 5,

[0045] Figure 7 a section of a folding ruler with a longitudinal section along the

[0046] Level S8-S9,

[0047] Figure 8 is an interrupted perspective instruction drawing of a further embodiment with two middle measuring elements and

[0048] Figure 9 is an interrupted perspective instruction drawing for a further alternative embodiment.

[0049] Before describing Figures 1 and 2 in detail, it should be noted that dipstick packages can generally be used on both sides, which can make a clear, detailed description difficult. In the following description of the figures, a selected side was therefore arbitrarily defined as the top side, which inevitably means that the opposite side is defined as the bottom side. However, this definition serves only to enable a clear and unambiguous description of the invention based on the figures. Of course, the designations could also have been interchanged, which would not change the invention for the person skilled in the art and the user.Thus, the folding measuring stick according to the invention is preferably scaled on both sides and can be used on both sides, with a double scale preferably being provided on the underside of the exemplary embodiments described below, which enables the folding measuring stick according to the invention to be used simultaneously as a niche measuring stick. As already explained above, the technical implementation of the invention is based on the fact that different, operatively connected locking elements are arranged in a groove 9 provided for this purpose in the tongue and groove 7 of a tongue and groove system, with the aid of which locking elements the measuring process is controlled. In the following examples, different embodiments of the invention are described, with the locking elements generally being assigned the reference numeral 10 and some special designs of the locking elements being identified with a further character sequence orare marked with alternative reference symbols in order to clarify the functionality and interaction of the locking elements.

[0050] Figure 1 shows a view of the top side 3 of a partially unfolded folding measuring rod 1 with an individual measuring element 2 taken out separately from the interior of the measuring rod package as an illustrative example. The folding measuring rod 1 and the individual measuring element 2 are drawn with interrupted sections due to their length in order to provide a compact overview. The measuring elements 2 arranged in the folding measuring rod are connected to one another by a tongue and groove connection, which is not visible in the selected illustration and will be explained in more detail later with reference to Figure 3. The uppermost measuring element 2 has an upper side 3 with a smooth surface on which the measuring units and the scale are printed. For economic reasons, only some of the units have been shown as examples for the entire measuring element 2.The scale was chosen so that the right end of the uppermost measuring element 2 forms the zero point, and the scale increases continuously to the left. In this embodiment, a length of 24 centimeters was chosen for the measuring elements 2, resulting in a length of 2.04 meters for the fully extended folding ruler 1, if two by two centimeters are required for each measuring element 2 to ensure stable attachment and fixation to the adjacent measuring elements 2 when extended.

[0051] On the second measuring element 2 located underneath in the folding rule 1, a groove 8 is drawn on the upper side 3, which extends from a stop web 6 to the end of the measuring element 2, which can be clearly seen in Figure 1 for the individual measuring element 2 chosen as an example. The individual measuring element 2 is also drawn in interrupted form, and for reasons of economy, a scale has been omitted entirely. This design with the groove 8 continues through the entire folding rule 1, which in the selected example consists of a total of ten measuring elements 2 and thus corresponds to the usual folding rules with a length of two meters. Also worth mentioning on the individual measuring element 2 is a locking element 10 designed as a prism 10-5, which projects out of the bottom of the groove 8 at the end of the groove 8 and points with its tip 10-6 in the extension direction.The exact positioning of the prism 10-5 in the groove 8 will be explained later with reference to Figure 3, in which the cutting plane is shown graphically, which is spanned by the cutting lines S1 and S2 shown in Figure 1.

[0052] Figure 2 is the counterpart to Figure 1 and shows the underside 4 of a partially extended folding measuring rod 1, also with a single measuring element 2 taken out separately from the interior of the measuring rod package as an illustrative example. At this point, it should be pointed out again that the folding measuring rod 1 according to the invention can be used on both sides, whereby in Figure 2, by definition, the lowest measuring element 2 is now pulled out and forms the beginning of the measuring process. The underside 4 of the lowest measuring element 2 also has a smooth surface printed with a measuring scale. Analogous to Figure 1, interruptions in the drawings were chosen to enable a compact representation, and for economic reasons, the scaling was omitted in whole or in part.The underside 4 is also designed so that the right end of the lowest measuring section 2 forms the zero point, although the scale is now selected so that the folding ruler 1 can also be used as a niche measuring rod. For this purpose, the measuring units on the subsequent measuring sections 2 are arranged in reverse and, for example, start at 44 centimeters on the second measuring section 2 when it is fully extended and end at 24 centimeters. With this arrangement, the niche measurement can then be read at the transition points from the lower to the next higher measuring section 2. For example, the arrangement of the folding ruler 1 shown in Figure 2 with two fully extended measuring sections 2 and a third slightly extended measuring section 2 would result in a niche measurement of 47 centimeters. If only the two lowest measuring sections 2 were extended, a niche measurement of 44 centimeters could be read.A particularly preferred embodiment of the folding measuring stick 1 according to the invention provides that, for example, on the back 4 of the folding measuring stick 1 shown in Figure 2, a double scale is provided, whereby on the second-to-lowest measuring element 2, the units of measurement would not only be entered in reverse, but a continuous scale would also be provided, which would then be located, for example, on the outer edge of the underside 4 of the measuring element 2. In this way, the back of the folding measuring stick 1 could be used not only as a niche measure, but also for normal length measurement. A comparable double scale can of course also be selected for the top side 3 of the folding measuring stick 1 shown in Figure 1, which would further facilitate the measurement overall, since in this case the user would no longer have to pay attention to which side of the folding measuring stick 1 they are using.This double scaling on both sides thus corresponds to a particularly advantageous embodiment of the present invention, which, however, is not captured in a figure due to the great graphic effort required, wherein the inventors have also assumed that the person skilled in the art can easily imagine a folding ruler 1 with a double scaling on both sides on the basis of the present figures 1 and 2.

[0053] The second lowest measuring element 2 and, of course, all middle measuring elements 2 have on their undersides 4, which are viewed from the perspective chosen in Figure 2, a dovetail-shaped, outwardly widening bung 7 which, starting from a flat receiving area 5 for a stop web 6 of the measuring element 2 located above, extends longitudinally continuously to the end of the measuring element 2. A bung groove 9 is arranged in the bung 7, which is open towards the receiving area 5 for the holding web 6 of the measuring element 2 located above, while it is delimited at the other end of the bung 7 by a holding web 11. Locking elements 10 are arranged inside the bung groove 9 itself, with two convexities 10-1 located opposite one another and projecting into the interior of the bung groove 9 in the front area of ​​the bung groove 9, which is open when pulled apart.Similar bulges 10-2, which also protrude into the interior of the bung groove 9, are also provided in the rear region of the bung groove 9, which lies in the extension direction. The bulges 10-2 in the rear region are combined with stop elements 10-3 arranged on both sides, each having a stop surface 10-4 oriented perpendicular to the extension direction. The interaction of the various locking elements 10 and the locking mechanism itself will be explained in detail later with the aid of Figure 4.

[0054] The subject of Figure 3 is a section of a cross-section through a folding ruler 1, formed by the section plane spanned by the section lines S1 and S2 in Figure 1, in which only the measuring element 2 located in the middle is fully encompassed. In this illustration, the trapezoidal groove 8 formed on the upper side 3 of the measuring element 2 can be seen, which is in operative connection with the dovetail-shaped bung 7 formed on the underside 4 and forms the tongue and groove connection between the individual measuring elements 2. The cross-section passes through the locking element 10, designed as a prism 10-5, which is arranged centrally on the base in the groove 8 and, in the pushed-together state of the folding ruler 1 shown here, projects into the bung groove 9 in order to come into operative connection there with the locking elements 10-1, 10-2, 10-3 and 10-4 provided for this purpose.This locking mechanism is explained in detail in the following Figure 4, which shows a horizontal section in the longitudinal direction through a measuring element 2 at the level of the section line S3 shown in Figure 3.

[0055] Figure 4 shows a horizontally oriented longitudinal section through a measuring element 2 in the section plane S3 from Figure 3. The section plane S3 was selected so that the locking elements 10-1, 10-2, 10-3, 10-4 and 10-5 acting in the bung groove 9 are recorded in their interaction. It should be noted that the longitudinal section, again drawn interrupted, depicts different states of the folding measuring rod 1 on both sides of the interruption, making it possible to illustrate in one drawing the functioning of the locking elements 10-1, 10-2, 10-3, 10-4 and 10-5 in the fully pushed together and fully pulled apart states. For the longitudinal section, a perspective with a view of the underside 4 was chosen, which allows a view into the bung groove 9.The left part of Figure 4 shows the position of the locking elements 10-1 and 10-5 in the fully collapsed state of the folding measuring rod 1, with the locking element 10-5, designed as a prism, pushed behind the locking curvatures 10-1 and fixed there. At the same time, the stop web 6 of the adjacent, overlying measuring element 2, positioned on the receiving area 5, would rest against the bung 7, which would correspond to the fully collapsed and closed state of the folding measuring rod 1. In the present section through the measuring element 2, the stop web 6 of an adjacent measuring element 2 cannot be shown. For a better understanding, however, an additional look back at Figures 1 and 2 is recommended, whereby the viewer must imagine that the separate measuring element 2 from Figure 1 is turned over and inserted with its locking element 10-5, designed as a prism, into the bung groove 9 of the separate measuring element 2 from Figure 2.At the same time, the tongue and groove connection between the two measuring elements 2 is also realized by inserting the tongue 7 of the measuring element 2 from Figure 2 into the groove 8 of the measuring element 2 from Figure 1.

[0056] The right-hand part of the interrupted Figure 4 shows the position of the locking elements 10-2, 10-3, 10-4, and 10-5 when the folding ruler 1 is fully extended. The locking element 10-5, designed as a prism, is displaced from its rest position behind the locking curvatures 10-1 into the locking position between the locking elements 10-2 and 10-3 at the other end of the bungee groove 9, with the prism 10-5 resting with its rear side 10-7 against the stop surfaces 10-4 of the stop elements 10-3, blocking further withdrawal and removal of the measuring element 2 from the folding ruler 1. From this position, the prism 10-5, with its tip 10-6 first, can be pushed back over the locking curvatures 10-2 through the bungee groove 9 into the rest position behind the locking curvatures 10-1.

[0057] Figure 5 is a perspective instruction drawing with two middle measuring elements 2, in which permanent magnets 12, 13 are provided as alternative locking elements. The measuring elements 2, shown in broken lines, have on their upper side 3 a trapezoidal, inwardly widening groove 8, from which a permanent magnet 12 protrudes in the upper measuring element 2. The permanent magnet 12 extends from the bung groove 9 on the underside 4 beyond the bottom of the groove 8 to the upper side 3. On its underside 4, the lower measuring element 2 has a bung 7 corresponding to the trapezoidal groove 8, in which a bung groove 9 is formed, delimited at both ends by retaining webs 11.Permanent magnets 12, 13 are provided as locking elements 10 in the bung groove 9, adjacent to the holding webs 11 in the base of the bung groove 9. When the measuring elements 2 are brought together in the collapsed state of the folding measuring rod 1, the permanent magnet 12 of the upper measuring element 2 interacts with the analogous permanent magnet 12 of the lower measuring element 2, whereby the measuring elements 2 are fixed in this position. The magnetic force is selected such that the folding measuring rod 1 holds together well in the collapsed state, but the measuring elements 2 can be pulled out with little force. After a measuring element 2 has been completely pulled out of the stack, the permanent magnet 12 protruding into the bung groove 9 is positioned over the permanent magnet 13 of the adjacent measuring element 2, which is flush with the bung groove 9, whereby the measuring element 2 is fixed in this position.Further withdrawal or removal of a measuring element 2 from the package is prevented by the retaining web 11, against which the permanent magnet 12 protruding into the bung groove 9 strikes during withdrawal. The section lines S4, S5, S6, and S7 indicate section planes, the sections of which are graphically illustrated in Figure 6 below.

[0058] The left-hand part of Figure 6 shows a cross-section of the folding measuring rod 1 with three measuring elements 2 in the plane S4-S5 from Figure 5, while the right-hand part of the figure, also with three measuring elements, shows the cross-section in the plane S6-S7 from Figure 5. These sections are intended to explain the installation conditions for the magnets 12, 13. The small permanent magnets 13 are embedded flush in the bottom of the bung groove 9, while the large permanent magnets 12 are in a through hole in the measuring element 2, starting from the bottom of the bung groove 9, where they are embedded flush, and extending beyond the bottom of the groove 8, so that in the assembled folding measuring rod 1 they protrude freely into the bung groove 9 of the adjacent measuring element 2. In addition, two auxiliary lines Hl and H2 are drawn, which are used in the following Figure 7 to show the positioning of the magnets 12, 13 in a longitudinal section.

[0059] In the lower partial drawing of Figure 7, the arrangement of the permanent magnets 12, 13 in the three measuring elements 2 of a folding measuring rod 1 is shown by way of example using a longitudinal section along the section plane S8-S9 from the upper partial drawing of Figure 7. In order to be able to classify the positioning of the magnets 12, 13 in the measuring element package more precisely, the auxiliary lines H1 and H2 from Figure 6 were introduced, whereby the auxiliary line H1 corresponds to the level of the bottom of the groove 8 and the auxiliary line H2 corresponds to the bottom of the bung groove 9. In comparison to Figure 6, the folding measuring rod in Figure 7 has been rotated so that the perspective view now shows the top side 3 of the uppermost measuring element 2 of a folding measuring rod 1.The interrupted sectional view shows the positions of the locking magnets 12, 13 when the folding ruler 1 is pushed together, with two small magnets 13 flush with the bung groove 9 on the underside 4 of the top measuring element 2. The level of the bottom of the bung groove 9 is marked by the auxiliary line H2. In the second top measuring element 2, on the right-hand side of the interrupted section, a large continuous magnet 12 can be seen, which extends from the bottom of the bung groove 9 of the second measuring element 2 over the bottom of the groove 8 marked by the auxiliary line H1 into the bung groove 9 of the first measuring element 2, where it interacts with the small magnet 13 of the top measuring element 2. The two upper measuring elements 2 are thus fixed to one another.When the lower measuring element 2 is fully extended to the left, the large magnet 12 interacts with the small magnet 13 on the right, thus fixing the extended position. Extension beyond this point is prevented by the retaining bar 11, against which the permanent magnet 12 abuts in this position.

[0060] Figure 8 is a perspective view of a pair of two measuring elements 2, in which the holding web 11 delimiting the bung groove 9 is a permanent magnet 14, wherein the permanent magnet 14 functions as a locking element and comprises a concave receiving area 16 for a magnetizable locking element counterpart 15. In the fully extended or pushed together state of the measuring rod 1, the elongated, diamond-shaped locking element counterpart 15 is positively inserted with one of its tips into the concave receiving area 16 and fixed there due to the magnetic force, wherein the magnetic force is selected such that the measuring element package holds together and the individual measuring elements 2 can be pushed apart or together without great effort.The triangular shape of the tip of the locking element counterpart 15 and the corresponding receiving area 16 is easy to manufacture and also advantageous in terms of handling when moving the measuring elements 2. Of course, other geometric shapes are also conceivable, such as a semicircle as the receiving area 16, which would then have to be combined with a cylinder as the locking element counterpart. The selection of which locking element should ultimately be used as a permanent magnet is also optional. Thus, the locking element counterpart 15 can of course also be provided as a permanent magnet, while the holding web is magnetizable, whereby the functionality of the measuring rod 1 remains unchanged. The same applies if both locking elements are magnetic.

[0061] Figure 9 shows a pair of measuring elements in which the holding webs 11 are combined with a clamp 17 open towards the bung groove 9, into which a cylinder 18 arranged in the groove 8 of the adjacent measuring element 2 engages as a locking element counterpart when pulled apart or pushed together.

[0062] As already mentioned at the beginning of the description of the figures, the above-described embodiments of the present invention are selected examples that are in no way to be seen as limiting, but merely serve to explain the basic principle of the present invention. The essential features of the folding ruler 1 according to the invention are that the measuring elements 2 are connected to one another via a tongue and groove connection and have a specific arrangement of locking elements in a provided tongue and groove groove 9, with which the fully retracted or extended state of the folding ruler 1 can be fixed.

[0063] Although the examples listed above exclusively show dovetail-shaped tongue and groove joints, the tongue and groove joint can also be realized with T-shaped connecting elements, which can be combined with locking elements in the same way as in the figures described above. In addition, other geometric configurations of the tongue and groove joint are conceivable, which will be obvious to the person skilled in the art.

[0064] It is considered essential to the invention that a special design of the bung 7 with a bung groove 9 is provided, which enables the interaction between the locking elements, wherein in addition to the embodiments, designs and arrangements of the locking elements described above as examples, a large number of further combinations and variations are conceivable, which are also obvious to the person skilled in the art and should therefore be covered by the claims formulated below.

[0065] LIST OF REFERENCE SYMBOLS

[0066] 1 folding ruler

[0067] 2 measuring elements

[0068] 3 Top side (measuring element)

[0069] 4 Bottom (measuring element)

[0070] 5 Mounting area for stop bar

[0071] 6 Stop bar

[0072] 7 bunging

[0073] 8 grooves

[0074] 9 tongue and groove

[0075] 10 locking element

[0076] 10-1 Curvature (front)

[0077] 10-2 Curvature (back)

[0078] 10-3 stop element

[0079] 10-4 stop surface

[0080] 10-5 prism

[0081] 10-6 peak

[0082] 10-7 Back

[0083] 11 Holding bridge

[0084] 12 permanent magnet

[0085] 13 Permanent magnet

[0086] 14 Permanent magnet

[0087] 15 Magnetizable locking element counterpart

[0088] 16 Recording area

[0089] 17 bracket

[0090] 18 Cylindrical locking element counterpart

[0091] 51 Section line (Figure 1)

[0092] 52 Cutting line (Figure 1) 53 Cutting line (Figure 3)

[0093] 54 Cutting line (Figure 5)

[0094] 55 Cutting line (Figure 5)

[0095] 56 Cutting line (Figure 5)

[0096] 57 Cutting line (Figure 5)

[0097] 58 Cutting line (Figure 7)

[0098] 59 Cutting line (Figure 7)

[0099] Hl auxiliary line (Figures 6, 7)

[0100] H2 auxiliary line (Figures 6, 7)

Claims

PATENT CLAIMS 1. An extendable folding measuring rod (1) constructed from a plurality of measuring elements (2) arranged one above the other, wherein the individual measuring elements (2) are connected to one another via a tongue and groove connection, wherein the uppermost measuring element (2) has a smooth upper side (3) and a longitudinally extending, outwardly widening bung (7) on its underside (4), as a counterpart thereto, the lowermost measuring element (2) has a smooth lower side (4) and a longitudinally extending, inwardly widening groove (8) on its upper side (3), the middle measuring elements (2) arranged between the two outer measuring elements (2) each have a longitudinally extending, inwardly widening groove (8) on their upper sides (3) and each have a longitudinally extending, outwardly widening bung (7) on their undersides (4),the bungs (7) and the grooves (8) are designed as a connection between the measuring elements (2) and at the same time as a guide for extending and pushing together the folding measuring rod (1), wherein additional, longitudinally extending bung grooves (9) are arranged in the bungs (7) for arranging and receiving locking elements, wherein the measuring elements (2) have pairs of locking elements which are matched to one another and are provided for locking and fixing the measuring elements (2) in the fully extended and fully pushed together state.

2. Folding measuring rod (1) according to claim 1, characterized in that the longitudinally extending bung (7) arranged on the underside (4) of the uppermost measuring element (2) starts from a flat receiving area (5) for a stop web (6) of the underlying measuring element (2) and extends longitudinally to the end of the measuring element (2), the groove (8) arranged on the upper side of the lowest measuring element (2) starts from a stop web (6) and extends continuously to the end of the measuring element (2), and the middle measuring elements (2) arranged between the two outer measuring elements (2) each have on their upper sides (3) a groove (8) which extends from a stop web (6) to the end of the measuring element (2) and widens inwards, and on their lower sides (4) each have a bung (7) which extends from a flat receiving area (5) for a stop web (6) of the measuring element (2) below to the end of the measuring element (2) and widens outwards.

3. Folding measuring stick (1) according to one of claims 1 or 2, characterized in that the locking elements (10) provided in the bung grooves (9) each comprise on both sides, mutually opposite curvatures (10-1, 10-2) projecting into the interior of the bung groove in the front area of ​​the bung groove (9) which is open in the extended state and in the rear area of ​​the bung groove (9) which is in the extension direction, wherein the curvatures (10-2) projecting on both sides in the rear area of ​​the bung groove (9) are additionally combined with stop elements (10-3) arranged on both sides, each having a stop surface (10-4) oriented perpendicular to the extension direction, wherein the locking elements (10-1, 10-2, 10-3, 10-4) in the bung grooves (9) interact with at least one corresponding, in the locking element (10) of an adjacent measuring element (2) arranged in the inwardly widening grooves (8),wherein the locking elements (10) are provided for locking and fixing the measuring elements (2) in the fully extended and retracted state, wherein the at least one corresponding locking element (10) of the adjacent measuring element (2) arranged in the inwardly widening grooves (8) is a free-standing isosceles prism (10-5), wherein the prism (10-5) is arranged centrally in the rear region of the groove (8) lying in the pull-out direction, wherein the tip (10-6) of the prism (10-5) formed by the same legs points in the pull-out direction, wherein the rear side (10-7) of the prism (10-5) rests against the stop surfaces (10-4) of the stop elements (10-3) when a measuring element (2) is pulled out completely, wherein the prism (10-5) engages between the stop elements (10-3) and the curvatures (10-2).

4. Folding measuring rod (1) according to claim 1 or 2, characterized in that the locking elements comprise at least one permanent magnet (12, 13, 14) integrated in a measuring element (2).

5. Folding measuring rod (1) according to claim 4, characterized in that a larger permanent magnet (12) sits firmly in a bore in the inwardly widening groove (8) and projects beyond the bottom thereof into the bung groove (9) of the adjacent measuring element (2), while a smaller permanent magnet (13) is flush with a bore in the bung groove (9), the permanent magnets (12, 13) being arranged such that the larger permanent magnet (12) comes to rest above the smaller permanent magnet (13) after the measuring element (2) has been pulled out and is fixed in this position due to the magnetic forces.

6. Folding measuring stick (1) according to claim 1, characterized in that the bung (7) has at its ends holding webs (11) delimiting the bung groove (9).

7. Folding measuring stick (1) according to claim 6, characterized in that the bung groove (9) is delimited at both ends of the bung (7) by holding webs (11), wherein the two permanent magnets (12, 13) are arranged in the immediate vicinity of the holding webs (11), so that when the measuring element (2) is pulled out, the larger permanent magnet (12) projecting into the bung groove (9) is stopped by the holding web (11) adjacent to the smaller permanent magnet (13), thus preventing unintentional removal of the measuring element (2) in question from the folding measuring rod (1).

8. Folding measuring stick (1) according to claim 6, characterized in that the holding webs (11) delimiting the bung groove (9) have a locking element function.

9. Folding measuring stick (1) according to claim 8, characterized in that the holding webs (11) comprise a permanent magnet (14) with a concave receiving area (16) for the positive reception of a magnetizable locking element counterpart (15).

10. Folding measuring rod (1) according to claim 8, characterized in that the holding webs (11) comprise a round clamp (17) open towards the bung groove (9) for the positive reception of a cylindrical locking element counterpart (18).

11. Folding measuring stick (1) according to one of claims 1 to 10, characterized in that the tongue and groove connection is designed as a dovetail connection, wherein the outwardly widening tongues (7) are dovetail-shaped and the corresponding inwardly widening grooves (8) are trapezoidal.

12. Folding measuring stick (1) according to one of claims 1 to 10, characterized in that the tongue and groove connection is T-shaped, the outwardly widening tongues (7) being T-shaped and the corresponding inwardly widening grooves (8) being inverted T-shaped.

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