Abstract:
An element for use with technical magnets having a mount, the mount to be located in a borehole having a base or counterbore. The element is disposed to lock the magnet mount in place in the borehole so it maintains an axial position oriented in the borehole as well as a radial bias position in the borehole. In this way the magnet surface will not intrude into the bore cylinder.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to magnet-spaced sensors and in particular magnets and bore holes. 
   2. Description of the Prior Art 
   Magnets are used in a wide variety of detectors. For example, magnetostrictive transducers having elongated wave guides that carry torsional strain waves induced in the wave guide when current pulses are applied along the wave guide through a magnetic field are well known in the art. A typical linear distance measuring device using a movable magnet that interacts with the wave guide when current pulses are provided along the wave guide is shown in U.S. Pat. No. 3,898,555. 
   Devices of the prior art of the sort shown in U.S. Pat. No. 3,898,555 also have the sensor element in a housing which also houses the electronics to at least generate the pulse and receive the return signal. The amplitude of the return signal detected from the acoustical strain pulse is, as well known in the art, affected by many parameters. These parameters include the position magnet strength, wave guide quality, temperature, wave guide interrogation current, and assembly tolerances. In the prior art, the wave guide is connected to a return wire to complete the electrical circuit necessary for the wave guide to generate the pulse which stimulates the return signal. 
   Several types of magnetic-based sensors are available for measuring linear or rotary position. Magnetic-based sensors have an advantage in that they provide non-contact sensing; so there are no parts to wear out. Examples of magnetic-based sensors are LVDTs, inductive sleeve sensors, and magnetostrictive sensors. 
   Technical magnets are often made of mechanically very brittle materials, with very simple geometries due to restrictions in the production technologies. In order to install these magnets in machine parts, additional mechanical components are always required for fixing them. These must ensure that the magnets are stressed very little mechanically and that the magnets also remain in a mechanically invariable position in the relevant environment. Additionally, the unavoidable mechanical tolerances of the magnet and of the installation environment must be compensated when mounting. Frequently, these tolerances are relatively high with magnets. 
   In the art, these requirements are frequently met at relatively high expenditure, by means of sealing compound, elastomers, sheet-metal retainers, screwing, snap rings, etc. In almost all cases, combination of several of the specified auxiliary means is required. Apart from the large quantity of components, the mounting expenditure is also relatively high 
   It is an object of the present invention to provide a solution for installation of magnet rings securely in bore holes. 
   SUMMARY OF THE INVENTION 
   The invention is a construction element, which provides a good solution for installation of magnet rings, ring-shaped or circular, generally round, brittle and mechanically sensitive components, e.g. sinter magnets in bore holes. 
   The elements of the invention include features of: 
   A Spring element which can compensate tolerances in radial and axial direction. 
   A spring element which locks the ring magnet axially in a suitable bore hole, by means of spring arms which support the magnet ring against the base of the bore and also support the spring element itself in a groove in the inner surface of the bore whereby the magnet ring is locked definitely in axial direction. 
   A spring element which fixes the ring magnet in a bore hole in radial direction by means of further spring arms tilted to it, which are located between the surface of the magnet and the inner mantle surface of the bore hole. These spring arms are distributed regularly over the circumference and, in untightened condition, directed at a suitable angle related to the tangent of the surface. When installing the ring magnet and the spring element into the bore hole, these spring arms are slightly distorted, whereby a permanent torsional spring pre-tension is provided. In this way, the magnet ring is definitely locked in radial direction. 
   By suitable geometrical design of all spring arms, the holding forces must be dimensioned so that they are sufficiently high enough to keep the magnet safely and precisely in radial and axial direction, and on the other hand, so that no unduly high mechanical forces are induced into the magnet ring. 
   Further construction elements for locking the ring magnet in axial and radial direction are not required. 
   The spring element is of metal. This ensures that the required defined pre-tension in axial and radial direction can be provided. There are no setting properties, like e.g. with plastics. Thus, the magnet ring is locked in position permanently and precisely and fixed safely. Preferably, the spring element metal should be of non-ferromagnetic material, in order not to affect the magnetic field of the magnet ring in an inadmissible way. 
   As the spring element is of metal and can be passivated necessary, good fluid compatibility is ensured with normal technical applications, especially oil or water-based hydraulic systems. 
   The spring element is designed as a punch-bended part and can be supplied preferably as a pre-punched part ( FIG. 3 ), such as a single element within a band of any length on rolls. Dependent of the number of spring elements which are cut off in one piece from the band, the spring elements can be used for magnet rings of various diameters. 
   By means of the proposed spring element, the installation procedure of a ring magnet into a bore hole is limited to inserting the magnet into the spring element and to inserting the spring element into the bore hole. As described, no further auxiliary means or elements are required. 
   Consequently, the installation of a ring magnet into a bore hole is a very low-priced operation. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the nature and objects of the present invention, reference should be had to the following figures in which like parts are given like reference numerals and wherein: 
       FIG. 1  is a side cross-sectional view of a bore hole in which the magnet ring is installed by means of the preferred embodiment of the present invention; and 
       FIG. 2  is a side cross-sectional view taken along lines  2 - 2  of  FIG. 1 ; and 
       FIG. 3  is an illustration of a pre-punched part for a spring element of the preferred embodiment. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIG. 1 , a cylindrical mounting form or cylinder  10  to support mounting a magnet therein is shown. Cylindrical form  10  has an outer cylindrical surface  15  and an inner cylindrical surface  20 . Inner cylindrical surface  20  forms the bore for the cylinder  10 . A counter bore  25  is formed having a larger diameter than the bore having surface  20  and terminating at shoulder  35 . A cylindrical grove  40  is formed in the inner surface of counter bore  25 . 
   A lock piece  50  is provided and sized to fit within counter bore  25  without the inner surface of locking piece  50  extending into the bore beyond the surface  20 . Lock piece  50  includes an outer dog  55  and an inner dog  60 . Locking piece  50  is made of spring-type material. Therefore, inner and outer dogs  55 ,  60  normally bias outwardly and inwardly, respectively, unless they are compressed. Each outer locking dog  55  is sized to fit within grove  40 . 
   As further shown in  FIG. 1 , a magnet  70  is sized to fit within the counter bore  25  without the inner surface  80  of the magnet  70  extending into the bore beyond the surface  20  when magnet  70  is locked in place. Thus magnet  70  has a thickness such that its inner surface  80  is flush with the inner surface  20  of cylinder  10  when magnet  70  is locked in place. 
   In operation, locking mechanism  50  is slid along inner surface  25  of cylinder  20  until outer locking dog  55  falls into or springs into grove  40 . Thereafter, magnet  70 , usually having its north surface on the inside  80  of the magnet  70 , may be slid along the inner side  90  of locking mechanism  50  locking dog  60 , depressing inner dog  60  until the end  100  of inner magnet  70  passes past inner locking dog  60  so that it no longer depresses inner locking dog  60 . Inner locking dog  60  will then spring up abutting end  100  of magnet  70 , thereby holding magnet  70  in place without glue and without cracking elastomers or without cracking or otherwise applying lateral pressure onto magnet  70 . The spring force of outer locking dog  55  further acts to center magnet  70  using a support ring  105  formed by to add further lateral support to magnet  70 . 
   On this basis: 
   A spring element  50  which can compensate tolerances in radial and axial direction. 
   A spring element  50  which locks the ring magnet  70  axially in a suitable bore hole, by means of spring arms  60  which support the magnet ring  70  against the base  25  of the bore  10  and also support the spring element  50  itself in a groove  40  in the inner surface  25  of the bore whereby the magnet ring  70  is locked definitely in axial direction. 
   A spring element  50  which fixes the ring magnet  70  in a bore hole  25  in radial direction by means of further spring arms  60  tilted to it, which are located between the surface  100  of the magnet  70  and the inner mantle surface of the bore hole  25 . These spring arms are distributed regularly over the circumference and, in untightened condition, directed at a suitable angle related to the tangent of the surface  20 . When installing the ring magnet  70  and the spring element  50  into the bore hole, these spring arms  60  are slightly distorted, whereby a permanent torsional spring pre-tension is provided. In this way, the magnet ring  70  is definitely locked in radial direction. 
   By suitable geometrical design of all spring arms  50 , the holding forces must be dimensioned so that they are sufficiently high enough to keep the magnet safely and precisely in radial and axial direction, and on the other hand, so that no unduly high mechanical forces are induced into the magnet ring  70 . 
   Further construction elements for locking the ring magnet  70  in axial and radial direction are not required. 
   The spring element  50  is of metal. This ensures that the required defined pre-tension in axial and radial direction can be provided. There are no setting properties, like e.g. with plastics. Thus, the magnet ring is locked in position permanently and precisely and fixed safely. Preferably, the spring element metal should be of non-ferromagnetic material, in order not to affect the magnetic field of the magnet ring in an inadmissible way. 
   As the spring element  50  is of metal and can be passivated, if necessary, good fluid compatibility is ensured with normal technical applications, especially oil or water-based hydraulic systems. 
   The spring element  50  is designed as a punch-bended part and can be supplied preferably as a pre-punched part ( FIG. 3 ), such as a single element  50  within a band of any length on rolls. Dependent of the number of spring elements  50  which are cut off in one piece from the band, the spring elements can be used for magnet rings of various diameters. 
   By means of the proposed spring element  50 , the installation procedure of a ring magnet  70  into a bore hole is limited to inserting the magnet  70  into the spring element  60  and to inserting the spring element  50  into the bore hole. As described, no further auxiliary means or elements are required. 
   Consequently, the installation of a ring magnet  70  into a bore hole  20 ,  25  is a very low-priced operation.