Clamping bracket for sensor

Abstract

A clamping bracket for a sensor (500) has a clamping sleeve and a clamping nut (200). The clamping sleeve has a first portion, wherein the clamping sleeve is divided by a slot into fins (112) extending parallel to its longitudinal axis, and a second portion having an external thread (121). The clamping nut (200) has a first portion wherein the clamping nut has an internal thread with which the clamping nut is screwed onto the external thread (121) of the clamping sleeve such that the fins (112) bend inward into the interior space of the clamping sleeve. In the second portion of the clamping nut, the inside surface of the clamping nut is inclined inwardly at an interior angle of at least 5 DEG.

Description

Technical Field

[0001] The invention relates to a clamping bracket for a sensor. Background Art

[0002] Cylindrical sensors, particularly inductive distance sensors, can have an external thread and be fastened to a hole in the housing wall using two nuts. Because these sensors have a very small switching distance of only a few millimeters, they must be positioned very precisely. After positioning the sensor, it is secured in place in the housing wall using two nuts attached to the external thread of the sensor housing. However, after maintenance or replacement, the sensor must be precisely positioned again.

[0003] Therefore, sensor holders that can be fastened to the housing wall have been proposed. When the sensor is replaced, the sensor holder remains in its position so that the switching distance can be re-established immediately.

[0004] DE 10 2012 023 193 B4 discloses a sensor holder having a threaded sleeve that accommodates a sensor and has an axially fixed stop inside a tube. Arranged on the threaded sleeve is a clamping device, by means of which the sensor to be positioned in the threaded sleeve can be clamped. The clamping device is a clamping sleeve that is positioned in the threaded sleeve in a rotationally fixed manner. The clamping sleeve has at least one radial extrusion element that projects elastically over the threaded sleeve and interacts with the internal taper of a nut arranged on the threaded sleeve, so that rotation of the nut causes a radial displacement of the at least one extrusion element directed toward the interior of the clamping sleeve. The extrusion element has a curved, conical outer surface that matches the internal taper of the nut.

[0005] DE 196 41 137 C2 discloses a sensor holder having a retaining element in the form of a ring, a sleeve for receiving a sensor, and a stop for limiting the positioning of the sensor in the end face area of ​​the sleeve. The sleeve consists of a non-grooved area and a slotted area relative to its longitudinal axis. The outer diameter of the non-grooved area is constant. The ring is movable on the sleeve. The stop is located in the non-grooved area on the inner end face of the sleeve. The slotted area has at least one axially elongated groove and at least one annular insert that can be fixed in the sleeve to receive the sensor. Each insert has a stud extending axially in the elongated groove area of ​​the sleeve. By shifting and / or rotating the retaining element in the slotted area of ​​the sleeve, a force can be applied to the stud so that the stud can be clamped onto the sensor.

[0006] However, these clamping brackets for sensors are made of metal and can negatively impact the sensitivity of the sensor, which is held in place within the metal-enclosed clamping bracket. Furthermore, a tool is required to clamp the sensor with these clamping brackets. However, these clamping brackets can result in unstable clamping. They also have only a small clearance relative to the outer diameter of the sensor, allowing the sensor to be inserted into the clamping bracket.

[0007] The object of the present invention is therefore to provide a clamping bracket for a sensor which can be made of a non-metallic material and can be clamped into the sensor without the aid of tools. Furthermore, the clamping bracket should be able to be used to clamp cylindrical sensors with different outer diameters. Summary of the Invention

[0008] This problem is solved by a clamping bracket for sensors, in particular for cylindrical sensors. The sensor can be, for example, an inductive proximity sensor or a proximity switch. The clamping bracket has a clamping sleeve and a clamping nut. The clamping sleeve has a first part, wherein the clamping sleeve is divided by grooves into fins extending parallel to its longitudinal axis. The clamping sleeve has an external thread in the second part. If the clamping sleeve is compressed in its first part by pressure from the outside, the inner diameter of the clamping bracket in its first part is reduced and the fins can clamp the sensor inserted into the clamping sleeve. Since the inner diameter of the clamping sleeve can here be larger than the outer diameter of the sensor, this clamping sleeve makes it possible to clamp sensors of different sizes. The principle of clamping a cylinder in a clamping sleeve is known, for example from the field of hose connectors and is referred to there as In principle, in a clamping sleeve, the fins of the clamping sleeve are separated from each other by grooves parallel to the longitudinal axis and pressed together. However, there, the cylinder only contacts the tips of the fins, resulting in an unstable clamping. This is insufficient for precise sensor positioning. However, according to the present invention, it has been discovered that by appropriately designing the clamping nut, the contact area between the fins and the sensor can be increased. When pressed together, the fins deform so that they contact the sensor with a portion of their inner surface rather than their tips, thus reliably preventing the sensor from slipping along the longitudinal axis of the clamping sleeve. The clamping nut has an internal thread. It is screwed onto the external thread of the clamping bracket via the internal thread, causing the fins to bend into the interior space of the clamping sleeve. To install the sensor in the clamping bracket, the sensor is inserted into the clamping sleeve, the clamping nut is guided over the sensor, and then tightened onto the external thread of the clamping bracket. The sensor can be removed from the clamping sleeve, and thus from the clamping bracket, by unscrewing the clamping nut. In order to intentionally bend the fins of the clamping sleeve so that they rest against the sensor with a large contact area, the clamping nut has a first part with an internal thread and a second part, in which the inner side surface of the clamping nut is inclined inwards at an internal angle of at least 5°. The internal angle forces the fins to form a curved shape determined by the internal angle so that they press against the sensor. Here, the second part does not have to rest directly on the first part. Instead, another part can be arranged between the two parts, for example, the other part does not have an internal thread, but its inner side surface is not yet inclined inwards. If the clamping sleeve has a part in which the clamping sleeve has neither a slot nor an external thread, the part of the clamping nut that has neither an internal thread nor an inclined inner side surface can receive the part of the clamping sleeve.

[0009] The sensor can be removed from the clamping bracket and reinserted without having to completely remove the clamping nut from the clamping bracket. Instead, it is sufficient to loosen the clamping nut. This makes it very easy to replace the sensor.

[0010] The length of the first part of the clamping sleeve and therefore the length of the fins is preferably in the range of 5 mm to 15 mm, particularly preferably in the range of 6 mm to 12 mm. It has been shown that, on the one hand, the length of the fins ensures a sufficiently large contact area between the clamping sleeve and the sensor and, on the other hand, provides sufficient stability for the first part of the clamping sleeve.

[0011] The first portion of the clamping sleeve preferably has 12 to 20 grooves.Furthermore, it is preferred that, in the uncompressed state of the clamping sleeve, each fin has a longitudinal axis extending parallel to the longitudinal axis of the clamping sleeve.

[0012] Preferably, the grooves each have an angle in the range of 10° to 50°, preferably 15° to 30°, relative to a line parallel to the longitudinal axis. This causes the fin to twist when the clamping nut is tightened. This results in better elastic behavior of the curved fin, meaning that greater tolerances of the sensor can be compensated.

[0013] To further improve the clamping effect of the clamping sleeve relative to the sensor, it is preferred that at least three fins each have a projection protruding into the interior of the clamping sleeve and have a triangular cross-section. It is particularly preferred that at least one-third of the fins have such projections, and very particularly preferred that at least half of the fins have such projections. In the compressed state of the fins, the projections enable the clamping sleeve to grip the surface of the sensor, further reducing the risk of the sensor shifting position within the clamping sleeve.

[0014] The clamping sleeve is preferably composed of at least one plastic. This allows the sensor to be mounted in the clamping sleeve in a non-metallic environment, which is particularly advantageous when the sensor is an inductive sensor. The elastic modulus of the plastic is preferably a maximum of 5 GPa, particularly preferably a maximum of 3 GPa, to enable simple and reversible bending of the fin. The elastic modulus can be determined, in particular, in a tensile test according to DIN EN ISO 527.

[0015] The plastic may contain fillers. Preferably, the plastic contains only non-conductive fillers, such as glass fibers, and no conductive fillers, such as metal fibers or carbon fibers. This also ensures that the sensor cannot be introduced into a conductive environment.

[0016] In addition to the clamping nut, other nuts can be attached to the clamping sleeve on its external thread. For example, the clamping sleeve can be fixed in place in the hole of the housing by inserting the clamping sleeve into the hole and tightening one fastening nut onto the external thread of the second part from each side of the housing wall.

[0017] In particular, a further section can be arranged between the first section and the second section, in which the clamping sleeve has neither a groove nor an external thread.

[0018] The length of the second portion of the clamping nut is preferably shorter than the length of the fin. Therefore, the fin protrudes from the clamping nut and thus contacts the sensor with a large contact area.

[0019] The internal angle is understood to be the angle between one of the inclined inner side surfaces of the clamping nut and the longitudinal axis of the clamping nut in a cross section. In order to press the fin tightly against the sensor and thus create a sufficiently large contact area with the sensor, an internal angle of at most 45° is preferred. A maximum of 30° is particularly preferred, and a maximum of 15° is very particularly preferred.

[0020] Furthermore, the inner angle is preferably smaller than the arctangent of the coefficient of static friction between the material of the clamping sleeve and the material of the clamping nut. This has the effect that the clamping sleeve and the clamping nut are self-locking when the clamping nut is tightened, so that the clamping bracket resists loosening caused by vibrations.

[0021] The clamping nut is preferably composed of at least one plastic. Therefore, the clamping nut does not create a conductive environment around the sensor. Any fillers in the plastic of the clamping nut are described in the same way as fillers in the plastic of the clamping sleeve. However, there are no specific requirements regarding the modulus of elasticity for the plastic of the clamping nut.

[0022] For the ease of manufacturing the clamping bracket, preferably clamping sleeve and clamping nut are made of identical plastics. In addition, this plastics is preferably a thermoplastic material, which means that clamping sleeve and clamping nut can be easily produced in an injection molding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description.

[0024] Figure 1 An isometric view of a clamping sleeve of a clamping bracket according to an exemplary embodiment of the present invention is shown.

[0025] Figure 2 Shows the basis Figure 1 Front view of the clamping sleeve.

[0026] Figure 3 A cross-sectional view of a clamping nut of a clamping bracket according to an exemplary embodiment of the present invention is shown.

[0027] Figure 4 The cross-sectional view shows how the clamping nut is screwed onto the clamping sleeve in an exemplary embodiment of the invention.

[0028] Figure 5 The insertion of a sensor into a clamping sleeve according to an exemplary embodiment of the present invention is illustrated in an isometric view.

[0029] Figure 6 An isometric view illustrates the assembly of a clamp bracket according to an exemplary embodiment of the present invention.

[0030] Figure 7 The deformation of the fins of the clamping sleeve in the clamping bracket according to an exemplary embodiment of the present invention is illustrated in a cross-sectional view. DETAILED DESCRIPTION

[0031] Figure 1 and Figure 2A clamping sleeve 100 for a clamping bracket according to an exemplary embodiment of the present invention is shown. The clamping sleeve 100 has the shape of a hollow cylinder and is divided into a first portion 110 and a second portion 120. In the first portion 110, the clamping sleeve 100 has sixteen grooves 111, which divide the first portion 110 into sixteen fins 112. Each fin 112 is, for example, 9 mm long. Between these two portions 110, 120 is another portion, for example 1 mm long, in which the clamping sleeve 100 has neither grooves nor external threads.

[0032] Each groove has an angle α of, for example, 22.5° relative to a line parallel to the longitudinal axis L of the clamping sleeve 100. Each second fin has a corresponding protrusion 113 of triangular cross-section, which projects into the interior of the clamping sleeve 100. In the second portion 120 adjoining the first portion 110, the clamping sleeve 100 has an external thread 121.

[0033] The clamping bracket according to an exemplary embodiment of the present invention has a clamping sleeve 100 and a clamping nut 200. Figure 3 As shown. The clamping sleeve 100 and clamping nut 200 are each made of, for example, polybutylene terephthalate (PBT) filled with 30% by volume glass fiber. The clamping nut 200 has a first portion 210 and a second portion 220. In the first portion 210, the inner surface of the clamping nut 200 extends parallel to the clamping nut's longitudinal axis L, which is generally identical to the longitudinal axis of the clamping sleeve and the clamping bracket. Internal threads 211 are formed in the inner surface of the first portion 210. At the end of the first portion 210, the inner surface initially continues to extend parallel to the longitudinal axis L until it merges into the second portion 220 of the clamping nut 200 in an inclined region 221. The length of the clamping nut 200 is, for example, 17 mm, and the length of the second portion 220 is, for example, 5.5 mm. Therefore, the second portion is shorter than the fin 112. For example, the angle β between the longitudinal axis L and the inclined inner surface 221 is 9.5°. This value is less than the inverse tangent of the coefficient of static friction between the material of the clamping sleeve and the material of the clamping nut, which is 0.8, or 38.7°.

[0034] Figure 4It is shown how the first part 210 of the clamping nut 200 is placed on the first part 110 of the clamping sleeve 100. If the clamping nut 200 is now screwed onto the clamping sleeve 100 so that its internal thread 211 engages with the external thread 121 of the clamping sleeve 100, the fins 112 pass into the second part 220 of the clamping nut 200 and are twisted there and bent toward the longitudinal axis L. In the process, the ungrooved part of the clamping sleeve 100 without the external thread 121 is located between the two parts 210, 220 of the clamping nut 200.

[0035] Figure 5 It shows how the clamping sleeve 100 is fixed in the opening of the housing wall 300. For this purpose, the first fastening nut 410 is screwed onto the outer thread 121 of the clamping sleeve 100 from the first part 110 until it abuts against the housing wall 300. The second fastening nut 420 is screwed onto the outer thread 121 from the second part 120 until it also abuts against the housing wall 300. The cylindrical sensor 500 can now be pushed into the clamping sleeve 100 in the direction of the arrow. Figure 6 As shown, the clamping nut 200 is first pushed onto the sensor 500 and then onto the first portion 110 of the clamping sleeve 100 and screwed onto the external thread 121 of the clamping sleeve 100. In this way, the fins 112 press against the sensor 500 and secure the latter in place.

[0036] Figure 7 2 illustrates this situation for the fins 112. In the second portion 220 of the clamping nut 200, the fins initially extend along the inclined side surfaces 221 and thus press against the outer wall of the sensor 500. Outside the clamping nut 200, the tips of the fins 112 bend away from the sensor 500 again. However, the resulting contact area between the side walls of the fins 112 and the sensor 500 is large, preventing the sensor 500 from slipping. At every other fin 112, the triangular protrusion 113 of the corresponding fin abuts against the sensor 500, thereby securing the sensor 500 more securely in place.

Claims

1. A clamping bracket for a sensor (500), comprising - a clamping sleeve (100) having a first portion (110), wherein the clamping sleeve is divided by a groove (111) into fins (112) extending parallel to its longitudinal axis (L), and a second portion (120) having an external thread (121), and a clamping nut (200) having a first portion (210), wherein the clamping nut has an internal thread (211), with which the clamping nut is screwed onto the external thread (121) of the clamping sleeve (100), so that the fins (112) are bent into the interior space of the clamping sleeve (100), It is characterized in that The clamping nut (200) has a second portion (220) in which an inner side surface of the clamping nut is inclined inwardly at an inner angle (β) of at least 5°.

2. The clamping bracket according to claim 1, characterized in that: The length of the first portion (110) of the clamping sleeve (100) is in the range of 5 mm to 15 mm.

3. The clamping bracket according to claim 1 or 2, characterized in that: The grooves (111) in the clamping sleeve (100) each have an angle (α) in the range of 10° to 50° relative to a line parallel to the longitudinal axis.

4. The clamping bracket according to any one of claims 1 to 3, characterized in that At least three fins (112) each have a protrusion (113) which protrudes into the inner space of the clamping sleeve (100) and has a triangular cross section.

5. The clamping bracket according to any one of claims 1 to 4, characterized in that The clamping sleeve (100) consists of at least one plastic.

6. The clamping bracket according to any one of claims 1 to 5, characterized in that The internal angle (β) is maximum 45°.

7. The clamping bracket according to any one of claims 1 to 6, characterized in that The inner angle (β) is smaller than the inverse tangent of the static friction coefficient between the material of the clamping sleeve (100) and the material of the clamping nut (200).

8. The clamping bracket according to any one of claims 1 to 7, characterized in that The clamping nut (200) consists of at least one plastic.

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