Abstract:
The invention relates to a bearing arrangement for mounting at least one machine element on a support, wherein the machine element is movably mounted on the support, wherein the bearing arrangement is provided with at least one measuring sleeve and with at least one measuring element on the measuring sleeve, wherein the measuring sleeve is formed separately from the support and wherein the measuring element is provided at least for measuring physical parameters and processes in the bearing arrangement.

Description:
FIELD OF THE INVENTION 
     Bearing arrangement for mounting at least one machine element on a support, the machine element being mounted movably on the support, the bearing arrangement having at least one measuring sleeve and having at least one measuring element on the measuring sleeve, the measuring sleeve being configured separately from the support and the measuring element being provided at least for measuring physical variables and processes in the bearing arrangement. 
     BACKGROUND OF THE INVENTION 
     A bearing arrangement of this type is described in the abstract of the publication of Japanese patent application JP58017328 A. It is customary to arrange the measuring sleeves between the bearing and the support for the bearing. The support is as a rule a housing or that part of a housing, in which or on which the machine element is arranged. However, the support can also be a separate bearing block or the like, by way of which the machine element is mounted. The machine element is, for example, an axle or shaft which is mounted by means of the bearing arrangement rotatably with respect to the support. The respective measuring sleeve in bearing arrangements according to the prior art is arranged radially between the outer ring of the bearing and the seat in the housing. The measuring sleeve is provided, for example, with strain gauges which react to elastic deformation of the measuring sleeve. The dimensional changes result from reaction supportive forces and displacements which are caused by the machine element which is loaded with forces/moments in the bearing. 
     The accuracy of the measured results in arrangements of this type of the prior art is dependent on many factors and therefore insufficient in some circumstances. The measured results are dependent, for example, on the rigidity of the support and on the installation tolerances, on temperature influences and on coefficients of thermal expansion of the materials of the housing and of the bearing ring. 
     Strain elements or the like are calibrated to a predefined initial state before operation of the bearing arrangement. The measuring device in bearing arrangements of the prior art is realized in transmissions on the bearing arrangement which has already been completely mounted in the housing, since, for example, the prestress of a press fit or the prestresses by means of screw connections on the measuring sleeve have to be taken into consideration during the calibration. The prestress which is reflected in deformations in the bearing is dependent on the above-mentioned tolerances and fluctuates from the installation in one transmission to the next installation in another transmission, with the result that the measuring devices have to be adapted individually for each transmission. The time for mounting the transmission is increased. Bearing arrangements having measuring devices of the generic type have therefore not established themselves so far in transmissions of mass production for cost reasons. 
     In a prestressed bearing arrangement, in which the coefficient of thermal expansion of the material of the measuring sleeve differs from the coefficient of thermal expansion of the bearing ring or the housing, changes in the operating temperature can lead to misleading measured results. It is possible, for example, that the prestress falls or increases on account of this difference. It is intended to measure only the stresses from the loadings on the bearing. Since, however, the prestress in the bearing arrangement can change at the same time as the loadings on the bearing, it cannot be determined clearly which influences have led to the measured results. 
     The installation space for the corresponding measuring elements or a corresponding sensor system is limited. For the measuring elements, a region which is correspondingly free of loadings has to be provided between the bearing ring and the housing, since the sensitive measuring elements, such as strain gauges, cannot be loaded by pressure, for example. 
     The outer ring and the measuring sleeve tend to migrate on the circumferential side, with the result that, for example, cable connections to the measuring elements can be subjected to a tensile load and destroyed over time as a result of the migration. The routing of the cables to and from the sensor system is difficult, since the cable leadthroughs in transmissions, for example, have to be sealed. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide a bearing arrangement, with which the above-mentioned disadvantages are avoided. 
     The object is achieved by the features of claim  1 . The bearing arrangement is received on the measuring sleeve. The machine element or a plurality of machine elements is/are mounted in the measuring sleeve by means of one or a plurality of bearings of the bearing arrangement. The measuring sleeve is fixed to the support, for example to a wall or to an intermediate wall of a transmission. The support can also be a pin, a shaft or the like, on which a machine element, such as a wheel, is mounted rotatably by means of the bearing arrangement. The bearing arrangement according to the invention is particularly well suited for mounting transmission shafts in transmissions. 
     The measuring sleeve carries the bearing. The machine element or elements is/are mounted in or on the measuring sleeve. All operating conditions, such as bearing support and reaction forces, displacements in the bearing or of the bearing and possibly temperature changes, are transmitted to the measuring sleeve without being influenced. The operating conditions can be measured at the measuring sleeve in an unadulterated manner, since the measuring sleeve with the bearing is connected by way of the bearing only on one side to the support and is therefore as far as possible free of the disruptive influences from the housing, for example from a tolerance-dependent press fit. The corresponding reactions from forces, moments and displacements at the measuring sleeve are not influenced directly by the surrounding construction. 
     The measuring arrangement can be calibrated before mounting on the support, since, for example, the corresponding plays in the bearing are already set before mounting on the housing. The bearing also still has these plays in an unchanged manner after mounting. The prestress will no longer change as a result of the installation, since the bearing is not pressed into a housing seat. This is significant, in particular, if bearing arrangements of this type are used in vehicle transmissions. Moreover, the measuring sleeve provides sufficient space for the arrangement of the measuring elements, such as for measuring sensors and for other sensors, and can be shielded or protected against external influences in a satisfactory manner. 
     The measuring sleeve itself is preferably of hollow-cylindrical configuration. An outer ring or outer rings of the bearing/the bearings is/are seated in the measuring sleeve. Alternative, one or more inner rings are seated on the measuring sleeve. One refinement of the invention provides for the measuring sleeve to be a constituent part of the bearing. The measuring sleeve has at least one but preferably two raceways. Each of the raceways is provided for one row of rolling bodies of the bearing in each case. The measuring sleeve is an inner ring if the raceway is formed circumferentially on the outside of the measuring sleeve or, as an alternative, is an outer ring, on which the raceway is formed circumferentially on the inside of the measuring sleeve. 
     The measuring sleeve is preferably a component which is produced from sheet metal by cold forming, is preferably of bowl-like configuration as a drawn part, and has a base and a collar. The collar which is preferably oriented radially to the outside is configured as a flange. The bearing or a seat of the bearing is shielded by way of the base against external influences. The collar is configured toward the flange, by way of which the bearing arrangement is flange-connected to the support, for example to a transmission housing. The sleeve is made, for example, from steel which can be drawn and optionally from ferromagnetic or nonferromagnetic steel. 
     The sleeve and/or the bearing ring are/is coated, for example, with a sensor layer. Sensor layers are to be understood as all layers which change their properties in a readable manner in the event of changes of materials or physical variables. 
     As a further refinement of the invention provides, the bearing is formed from two bearing rings which are arranged concentrically with respect to one another and are of sleeve-shaped configuration. Both rings are preferably drawn parts and have the corresponding raceways for the rolling bodies. One of the sleeves is provided with the flange, by way of which the bearing arrangement is fixed to the support. One of the bearing rings or, as an alternative, both of the bearing rings is/are configured as measuring sleeve. 
     In the context of the bearing arrangement according to the invention, the measuring sleeve is to be understood as a sleeve, on which changes to one or more physical variables or processes are measured either directly or indirectly by means of a corresponding sensor system. However, a measuring sleeve is also a sleeve which is a carrier for a sensor system, by way of which changes in state variables and/or processes which take place away from the sleeve are sensed. Combinations of the above-mentioned refinements are also conceivable. Examples are as follows:
         The measuring sleeve is a strain sleeve which is equipped with corresponding strain sensors. The strain sleeve reacts to the loadings of the machine element by elastic deformations. The deformations are sensed by the sensors on the sleeve and are forwarded to a corresponding evaluation device in the bearing arrangement or outside the bearing arrangement. The expanding behavior of strain sleeves of this type can be influenced in a targeted manner by a corresponding design of expanding sections of the measuring sleeve. This is possible, for example, by predefined material cross sections or by the targeted introduction of slots and similar interruptions or weakened sections of the structure of the strain sleeve.   Variables which are to be determined in/on the structure of the strain sleeve are sensed on the measuring sleeve by way of corresponding sensors directly or in the immediate vicinity of the measuring sleeve. Variables of this type are, for example, changes in the magnetism of the strain sleeve, operating temperatures or vibrations of the bearing which are transmitted to the measuring sleeve. Measuring arrangements of this type supply very accurate results, in particular, in bearing arrangements, in which the measuring sleeve at the same time has the raceway/raceways of the corresponding bearing.   A sensor or a plurality of sensors or other sensing elements are placed on the measuring sleeve, for example on the sleeve and/or on the flange and/or on the base. The sensors are directed toward signal generators through the wall of the measuring sleeve or through a recess in the measuring sleeve. Signal generators of this type are, for example, encoders for rotational speed measurement or optical measuring arrangements. Here, the measuring sleeve is fixed relative to the support. Here, the encoder is arranged on the rotating bearing ring.   The measuring sleeve is provided with at least one or with a plurality of measuring gaps or measuring openings of a defined and variable passage cross section. A measuring optical system, for example a light source, and a suitable sensor are directed toward the measuring openings. The measuring openings are made in sections of the measuring sleeve which are expected to be subjected to a tensile or compressive load on account of the bearing reactions. The passage cross section is enlarged or reduced in one or two directions as a result of the stresses which are produced on account of these reactions. These changes are sensed by the sensor/sensors and are forwarded to a corresponding evaluation device.   On account of loadings, individual sections of the measuring sleeve change their position by tilting or by twisting or by expansion or by compression relative to one another. These changes are sensed by way of a corresponding sensor system. It is therefore conceivable to sense changes in the position of the cylindrical measuring sleeve with respect to the flange as a result of angular measurements. Here, both measuring arrangements can be measured for measuring deviations from the normal position of the rotational axis in the bearing arrangement, such as tilting and deflection, for example by angular measurement, and also rotations with respect to one another about the rotational axis, for example by radian measure.   The displacements of individual components of the bearing arrangement relative to one another are measured. Changes of this type are, for example, the tilting of the inner ring with respect to the outer ring which is fixed on the support or the tilting of the outer ring with respect to the inner ring which is fixed on the support. Changes in the axial spacing of the inner ring, a shaft or an axle from the base of the measuring sleeve can also be measured. It is conceivable, for example, that the outer ring of the bearing arrangement is at the same time the measuring sleeve, on which the sensor system is arranged. Axial approaches of the inner ring to the base of the measuring sleeve or radial approaches of the inner ring to the cylindrical measuring sleeve are detected on the outside by way of the sensor system.       

     The above-mentioned arrangements can also be combined as desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be better understood and appreciated by reading the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates the bearing arrangement where an inner bearing ring is a measuring sleeve; 
         FIG. 2  illustrates an alternative arrangement of the bearing arrangement sensor system on the measuring sleeve; 
         FIG. 3  illustrates the bearing ring arrangement having a measuring sleeve with the sensor system or measuring system fixed on a flange; 
         FIG. 4  illustrates the bearing ring arrangement having a measuring sleeve with the sensor system or measuring system arranged on a hollow-cylindrical section of the measuring sleeve; 
         FIG. 5  illustrates the bearing arrangement outwardly closed being flange-connected on the outside to a support; 
         FIG. 6  illustrates an alternate view of the bearing arrangement outwardly closed being flange-connected on the outside to the support; 
         FIG. 7  illustrates an alternate embodiment of the bearing arrangement where a measuring element or sensor system is arranged on the base of the measuring sleeve; and 
         FIG. 8  illustrates the sensor system or measuring element arranged on a hollow-cylinder section of the measuring sleeve. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is explained in greater detail in the following text using exemplary embodiments. 
       FIG. 1  shows a bearing arrangement  1 , in which an inner bearing ring  2  is the measuring sleeve  3 . The measuring sleeve  3  has a raceway  4  on the outside for a row of rolling bodies  5  in the form of balls which are held in a cage  24 , The raceway  4  is preferably inserted in the measuring sleeve  3  without cutting. 
     The inner bearing ring  2  is surrounded by an outer bearing ring  6  of the bearing arrangement  1 . A raceway  20  for the rolling bodies  5  is formed on the inside of the outer bearing ring  6 . The outer bearing ring  6  is pressed into a machine element  7 . The machine element  7  is shown in a very simplified manner as a hollow cylinder and can be, for example, a hollow shaft of a transmission. 
     The measuring sleeve  3  is a drawn part of bowl-like configuration having a hollow-cylindrical section  8 , having a base  9  and having a radially outwardly directed flange  10 . 
     The radial flange  10  is provided with through holes  11 . Fastening elements (not shown), such as threaded bolts, engage through the through holes  11  and into corresponding fastening holes  18  of the support  13 . The bearing arrangement  1  is fastened by way of the flange  10  to the support  13  (shown only in basic form). 
     The support  13  is, for example, a constituent part of a transmission housing. The measuring sleeve  3  is fixed on the outside to the support  13  and protrudes freely with the hollow-cylindrical section  8  through a hole  15 . The connection is sealed with a seal  14 . 
     A sensor system  19  and measuring elements  16  are attached on the flange  10 . The measuring elements  16  are, for example, strain elements. The machine element  7  is supported in the loaded and unloaded state on the measuring sleeve  3  via the rolling bodies  5 . The loadings of the measuring sleeve  3  lead to tensile or compressive stresses on the flange  10  and are registered by the measuring elements  16 . The measured results from deformations are collated and forwarded via a line  17  to an evaluation unit (not shown) and evaluated accordingly. 
       FIG. 2  shows an alternative arrangement of the sensor system on the measuring sleeve  3 . The sensor system  19  is attached on the inside in the measuring sleeve  3  in the hollow-cylindrical section  8  in the immediate vicinity of the raceway  20  and is therefore suitable, for example, for measuring deformations or sound on the inner ring of the bearing arrangement. 
       FIGS. 3 and 4  show a bearing arrangement  21  having a measuring sleeve  22 . The measuring sleeve  22  has a raceway  23  for the rolling bodies  5  on the inside. The rolling bodies  5  are guided in the cage  24  and are arranged radially between the measuring sleeve  22  and an inner ring  25 . The inner ring  25  is seated on a machine element  26  in the form of a shaft. The measuring sleeve  22  has the radially outwardly directed flange  10  which has through holes  11  and by way of which the bearing arrangement  21  is placed on the support  13  on the inside or outside. 
     The sensor system  19  or a measuring element  12  is fixed, for example, on the flange  10  in the arrangement according to  FIG. 3  and is arranged on a hollow-cylindrical section  27  of the measuring sleeve  22  in the arrangement according to  FIG. 4 , as an alternative to  FIG. 3 . 
       FIG. 5  and  FIG. 6  show an outwardly closed bearing arrangement  28  which is flange-connected on the outside to the support  13 . The bearing arrangement  28  is particularly suitable for the applications on bearings of transmission shafts  29 , since the bearing arrangement  28  which is preassembled and is precalibrated in terms of measuring technology can be placed onto a housing  33  from the outside. The bearing arrangement  28  has a measuring sleeve  30  of bowl-like configuration having a closed base  31 , a hollow-cylindrical section  32  and a flange  10 . The bearing arrangement  28  and the housing  33  are closed to the outside by the measuring sleeve  30 . The seat of the bearing arrangement  28  on the housing is sealed by means of a seal  34 . 
     On the inside, the measuring sleeve  30  has a raceway  40  for the rolling bodies  5 . Furthermore, the bearing is provided with an inner ring  35  of bowl-like configuration. The inner ring  35  is seated in the transmission shaft  29  which is configured in this case as a machine element  36 . The sensor system  19  or a measuring element  37  is seated optionally on the flange  10  ( FIG. 5 ) or on the hollow-cylindrical section  32  ( FIG. 6 ). 
     Bearing arrangements are also provided, in which both the hollow-cylindrical section and the flange are provided optionally on the inside or outside with measuring elements. 
       FIG. 7  shows an alternative refinement of the bearing arrangement  28 , in which at least one measuring element  37  or a sensor system  19  is arranged on the base  31  of the measuring sleeve  30 . For example, signals can be detected by way of a sensor system  19  of this type through the closed base  31  or, as shown in  FIG. 7 , through an opening  38 . For instance, according to the example from  FIG. 7 , the spacing of the inner ring  35  from the measuring sleeve  30  in the axial direction can be measured. It is also conceivable that the inner ring  35  is provided on the end face with an alternatively polarized signal generator  39 , with the result that the rotational speed of the shaft  29  can be measured by the sensor system  19 . 
       FIG. 7  shows a bearing arrangement  41  having a measuring sleeve  42 . On the inside, the measuring sleeve  42  receives a bearing ring  43  in the form of an outer ring. A raceway  44  for the rolling bodies  5  is formed on the outer ring on the inside. The rolling bodies  5  are guided in the cage  24  and are arranged radially between the bearing ring  43  and an inner ring  25 . The inner ring  25  is seated on a machine element  26  in the form of a shaft. The measuring sleeve  42  has the radially outwardly directed flange  10  which has through holes  11  and by way of which the bearing arrangement  41  is placed on the inside or the outside on the support  13  (not shown in this case). 
     In the arrangement according to  FIG. 8 , the sensor system  19  or a measuring element  12  is arranged on a hollow-cylindrical section  45  of the measuring sleeve  42 . Additionally, as an alternative, the sensor system  19  can also be fastened, for example, to the flange  10 . 
     LIST OF DESIGNATIONS 
     
         
           1  Bearing arrangement 
           2  Bearing ring, inside 
           3  Measuring sleeve 
           4  Raceway, outside 
           5  Rolling body 
           6  Bearing ring, outside 
           7  Machine element 
           8  Hollow-cylindrical section 
           9  Base 
           10  Flange 
           11  Through hole 
           12  Measuring element 
           13  Support 
           14  Seal 
           15  Hole 
           16  Measuring elements 
           17  Line 
           18  Fastening hole 
           19  Sensor system 
           20  Raceway, inside 
           21  Bearing arrangement 
           22  Measuring sleeve 
           23  Raceway, inside 
           24  Cage 
           25  Inner ring 
           26  Machine element 
           27  Hollow-cylindrical section 
           28  Bearing arrangement 
           29  Transmission shaft 
           30  Measuring sleeve 
           31  Base 
           32  Hollow-cylindrical section 
           33  Housing 
           34  Seal 
           35  Inner ring 
           36  Machine element 
           37  Measuring element 
           38  Opening 
           39  Signal generator 
           40  Raceway, inside 
           41  Bearing arrangement 
           42  Measuring sleeve 
           43  Bearing ring 
           44  Raceway 
           45  Section