Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/30—Parts of ball or roller bearings
  • F16C33/38—Ball cages
  • F16C33/44—Selection of substances
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
  • F16C19/52—Bearings with rolling contact, for exclusively rotary movement with devices affected by abnormal or undesired conditions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/30—Parts of ball or roller bearings
  • F16C33/66—Special parts or details in view of lubrication
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
  • F16C33/30—Parts of ball or roller bearings
  • F16C33/66—Special parts or details in view of lubrication
  • F16C33/6637—Special parts or details in view of lubrication with liquid lubricant
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M13/00—Testing of machine parts
  • G01M13/04—Bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
  • F16C2202/00—Solid materials defined by their properties
  • F16C2202/30—Electric properties; Magnetic properties
  • F16C2202/32—Conductivity

Definitions

• the present invention relates to a method and a device for monitoring the state, especially the thick ⁇ ness and/or quality, of a lubricating film in a rolling bearing having rolling elements and races on two mem- 5 bers which are movable in relation to each other by means of the rolling elements.
• the invention also relates to a cage for the rolling elements which can be used in the method and device of the invention... It is previously known to rely on changes in 10 the electric properties of a lubricating film layer for monitoring and determining the state of the layer, including its thickness and the quality of the lubri ⁇ cant.
• EP-A-68 568 discloses for instance a measuring system for"determining capacitive changes in a rolling 15 bearing. This measuring system requires the use of a special, insulatedly mounted measuring ring, which reduces the usefulness of the system.
• the object of the present invention is to pro ⁇ vide a method, a device and a rolling-element cage 20 of the type indicated in the introduction to this specification, which entails a simple, effective and essentially generally applicable solution to the prob ⁇ lems involved in using the capacitance in rolling bearings for monitoring the state of the lubricating 25 film in the bearing.
• the method for moni- * % toring the state of the lubricating film is character ⁇ ized in that an electric measuring signal is transmitted • ⁇ to a rolling-element cage or other member accompanying
• the device for carry ⁇ ing out the method is characterized by a rolling-element cage or other member accompanying the rolling elements in the bearing and having electrically conductive portions adjoining the rolling elements by the inter ⁇ mediary of lubricating film, the area of said portions substantially exceeding the contact area between the rolling elements and the races of the bearing, and a detector for determining the effect of a change in the state of the lubricating film between the rolling elements and the races of the bearing on the electric parameters of an electric measuring signal transmitted to the rolling-element cage or said other member.
• the cage for the rolling elements is characterized by two or more in ⁇ terconnected, separately electrically conductive parts having conductive portions contiguous to spaces for accommodating rolling elements, and held together by electrically insulating parts.
• Fig. 1 is a radial cross-section of a part of a rolling bearing.
• Fig. 2 is a cross-sec- ⁇ tional view taken along the line II-II in Fig. 1.
• Fig. 3 shows an embodiment of a rolling-element cage according to the invention.
• Fig. 4 is an electric circuit diagram illustrating an inductively coupled device according to the invention with a rolling-element cage according to Fig. 3.
• Fig. 1 is a radial cross-section of a part of a rolling bearing.
• Fig. 2 is a cross-sec- ⁇ tional view taken along the line II-II in Fig. 1.
• Fig. 3 shows an embodiment of a rolling-element cage according to the invention.
• Fig. 4 is an electric
• FIG. 5 is an electric cir- cuit diagram illustrating a capacitively coupled device according to the invention.
• the rolling bearing partially shown in Fig. 1 has rolling elements 1, e.g. balls, rolling on races on an outer ring 2 and an inner ring 3 which thus form members movable in relation to each other by means of the rolling elements 1.
• rolling elements 1 e.g. balls
• an annular cage 4 having recesses for the rolling elements 1.
• the portions of the cage 4 adjoining the rolling elements 1 are electrically conducting and have a substantially larger area than the contact area between the rolling elements 1 and the races on the outer ring 2 and the inner ring 3.
• the electrically conductive portions adjoining the rolling elements by the intermediary of lubricating film may be provided on a special member separated from the cage but accompanying the rolling elements.
• the whole cage 4 or said alternative member may consist of an electrically conductive material, e.g. metal or an electrically conductive plastic, so that said electrically conductive portions are electrically interconnected.
• the elec ⁇ trically conductive portions are however electrically interconnected in two or more groups, which can be achieved in that the cage 4 or said alternative member consists of two or more interconnected, separately electrically conductive parts which are held together by electrically insulating parts.
• the electrically conductive parts may be of metal or conductive plastic, while the electrically insulating parts may consist of insulating plastic.
• An example of such a rolling-element cage 4 is shown in Fig. 3 where the cage 4 consists of two electrically conductive parts 5 and 6 which are separated by two electrically insulating parts 7 and 8.
• the conductive parts 5 and 6 occupy the major portion of the circumference of the cage 4 and contain all the recesses for the rolling elements 1.
• the conductive parts 5 and 6 may be electrically inter ⁇ connected by a coil 9 which, as shown in Fig. 2, may be wound around the outer side of the cage 4 in the space between the rolling elements 1 for inductive coupling, e.g. to a coil 10 (see Fig. 4) disposed externally of the cage.
• the electric circuit diagram shown in Fig. 4 relates to an embodiment of the inventive device that uses the rolling-element cage according to Figs. 2 and 3.
• the same reference numerals as in Figs. 1-3 are used in Fig. 4.
• the coil 10 is connected in a circuit having an AC source 11 and a detector 12 by means of which the state of a lubricating film in the rolling bearing should be monitored by determining electric parameters of a measuring signal produced by the generator 11 and inductively transmitted in a contactless manner by the coil 10 to the coil 9 which is connected between the conductive parts 5 and 6 of the rolling-element cage 4.
• Capacitors Cl, C2, C3 and C4 in Fig. 4 represent the capacitance between the cage part 5, 6 and the rolling elements 1 accommodated therein.
• Capacitors C12, C22, C32 and C42 represent the capacitance between the rolling elements 1 and the outer bearing ring 2, while capa ⁇ citors C13, C23, C33 and C43 represent the capacitance between the rolling elements 1 and the inner bearing ring 3. Since the electrically conductive portions of the cage 4 (alternatively the separate member) adjoining the rolling elements 1 by the intermediary of lubricating film have an area which is substantially larger than the contact area between the rolling ele ⁇ ments 1 and the races on the outer ring 2 and the inner ring 3, the capacitors Cl, C2, C3 and C4 have a substantially higher capacitance than the capacitors C12-C43.
• a change in the capacitance of any of the capacitors C12-C43 i.e. a change in the state of the lubricating film between a rolling element 1 and either of the races, may have a measur ⁇ able effect on the signal parameters in the primary circuit 10, 11 and 12 and, hence, can be monitored by means of the detector 12.
• the detection and measurement may be regarded .as performed on series consisting of cage - rolling elements - races - rolling elements - cage.
• a capacitive transmis ⁇ sion may be used, as shown in the embodiment of Fig. 5.
• the electrically conductive portions of the cage 4 (or the separate member accompanying the rolling elements) which adjoin the rolling elements are all electrically connected to each other and to one electrode 13 in a coupling capacitor whose other electrode 14 may consist of a fixed, electrically conductive ring disposed axially beside the rolling- element cage 4.
• the cage 4 may thus form said elec ⁇ trode 13.
• the capacitance of this coupling capacitor 13, 14 should be high as compared with the capacitance between the conductive portions of the cage 4 adjoining the rolling elements, and the rolling elements 1.
• the measuring signal generator 11 and the detector 12 are connected in series between the coupling capacitor electrode 14 and e.g. the outer bearing ring 2.
• the cage 4 may be provided with more than one coil, in which case it is suitably divided into more than two conductive parts.
• the detector 12 can measure any electric parameter in its circuit that reflects a change in any one of the capacitors C12-C34, i.e. a change in the state of the lubricating film between one of the rolling elements 1 and either of the races.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Rolling Contact Bearings (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=20355779

Family Applications (1)

Country Status (2)

Cited By (5)

Citations (2)

• 1984
  • 1984-05-07 SE SE8402451A patent/SE447010B/sv not_active IP Right Cessation
• 1985
  • 1985-11-06 WO PCT/SE1985/000440 patent/WO1987003053A1/en unknown

Patent Citations (2)

Non-Patent Citations (1)

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