Machine with thermally compensated bearings
AssigneeThe Timken Company
InventorsHarold E. Hill, Ronald P. Dickerhoff, Gary E. Kreider
Life of this patent
Estimating the term…
Abstract
An aluminum transmission or transaxle case contains a steel shaft which is supported in the case on two directly mounted tapered roller bearings, so that the two bearings confine the shaft both radially and axially. To compensate for the differences in expansion and contraction between the aluminum case and the steel shaft as the transmission or transaxle experiences variations in temperature, a race of at least one of the bearings is fitted with a compensating ring having a coefficient of thermal expansion greater than that of the case or shaft. As a consequence, the bearings operate at a generally uniform setting over a wide range of temperature variations.
Claims19
In combination with a case having abutments, a shaft in the case and also having abutments presented toward and spaced axially from the abutments of the case, the shaft being formed from a material which has a different coefficient of thermal expansion than the material of the case, and at least two bearings supporting the shaft in the case, with the bearings being configured to accommodate both axial and radial loads and being mounted in the case and on the shaft between the abutments of the case and the shaft where they are in opposition to each other, so that the bearings confine the shaft both axially and radially in the case, the bearings having inner and outer races each of which is presented opposite to one of the abutments and is provided with a raceway that faces the raceway of the other race for the bearing, and rolling elements which roll along the raceways, the improvement comprising:
- one of the races of at least one of the bearings having a recess which opens toward the abutment opposite which that race is presented and compensating means located in the recess and against the abutment to which the recess opens for responding to temperature changes in the bearing to thereby compensate for differential thermal expansion and contraction between the shaft and the case so that the bearings maintain a more uniform setting over a wide range of temperature variations.
In combination with a case having a shoulder, a shaft in the case and being formed from a material which has a different coefficient of thermal expansion than the material of the case, and at least two bearings supporting the shaft in the case, with the bearings being configured to accommodate both axial and radial loads and being mounted in the case and on the shaft in opposition to each other so that the bearings confine the shaft both axially and radially in the case, the bearings having races provided with raceways and rolling elements which roll along the raceways, at least one of the bearings being a tapered roller bearing having one of its races in the form of a cone provided with an outwardly presented raceway, the other of its races in the form of a cup provided with an inwardly presented raceway and located adjacent to the shoulder of the case, and its rolling elements in the form of tapered rollers located between the raceways of the cup and cone, the improvement comprising:
- compensating means fitted into the cup of the tapered roller bearing and being against the shoulder of the case for responding to temperature changes in the bearing to thereby compensate for differential thermal expansion and contraction between the shaft and the case, so that the bearings maintain a more uniform setting over a wide range of temperature variations.
A machine comprising:
- a case formed from a metal and containing abutments;
- a shaft mounted in the case and being formed from a metal having a coefficient of thermal expansion that is less than the coefficient of thermal expansion for the metal of the case, the shaft having abutments that are presented toward the abutments of the case;
- a pair of single row tapered roller bearings located in the case and around the shaft and being between the abutments of case and shaft, the bearings further being in opposition to each other so that they transmit radial and axial loads between the shaft and the case, each tapered roller bearing including a cone which is located around the shaft and has an outwardly presented raceway and a back face hat is presented toward one of the abutments on the shaft, a cup having an inwardly presented raceway and a back face that is presented toward one of the abutments in the case, and tapered rollers arranged in a single row between the raceways of the cone and cup, at least one of the cups containing a rabbet;
- a compensating ring fitted into rabbet of the cup and projecting beyond the back face of the cup where it bears against the case abutment toward which the cup back face is presented, the compensating ring being formed from a material that has a coefficient of thermal expansion greater than the coefficients of thermal expansion for the materials from which the case and shaft are formed and being oriented such that it compensates for thermal differential expansion and contraction between the case and shaft, so that the bearings remain at a more uniform setting over wide temperature variations.
A tapered roller bearing comprising:
- a first race in the form of a cone having an outwardly presented tapered raceway and a back face located beyond the large end of the raceway;
- a second race in the form of a cup that is located around the cone and has an inwardly presented raceway and a back face at the small end of the raceway;
- one of the races further having a backing surface that is presented in the same direction as its back face;
- tapered rollers located in a single row between the raceways of the cup and cone;
- and a compensating ring carried by cup and being against the backing surface of that race, the ring being formed from a material having a high coefficient of thermal expansion.
Dependencies are inferred from the claim text.