Tapered Roller Bearing Pocket Structure for Low Torque and Seizure Resistance
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Solution Overview
Problem
Tapered roller bearings face issues with torque loss and reduced life due to increased load and foreign substances in automotive applications, particularly under oil lubrication environments, where lubricating oil flow resistance leads to seizure and reduced durability.
Innovation Solution
The use of steel components with specific carbon, silicon, manganese, and chromium compositions, along with a nitrogen concentration of 0.3 mass% or more in surface layers, and a trapezoidal pocket design with cutouts in the holder to reduce lubricating oil retention and enhance seizure resistance and life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating oil flows into the bearing from the inner diameter side of the holder into the inner ring side, then the proportion of lubricating oil reaching the contact surface is increased, but torque loss increases due to flow resistance
Solution Approach 1:
The patent changes the physical parameters of the contact surface by introducing a nitrogen-rich layer with specific concentration (0.05-2.0 mass%) and controlling grain size number (greater than 10), thereby improving seizure resistance while managing torque loss through material property optimization
Solution Approach 2:
The nitrogen-rich layer acts as an intermediary between the contact surfaces, providing a protective barrier that reduces direct metal-to-metal contact and friction, thus improving seizure resistance while controlling torque loss
2Reliability
If the bearing is designed to retain more lubricating oil for better lubrication, then seizure resistance improves, but torque loss increases due to increased flow resistance
Solution Approach 1:
The patent optimizes the chemical composition parameters of the steel (carbon: 0.6-1.50 mass%, silicon: 0.15-2.50 mass%, manganese: 0.30-1.50 mass%, chromium: 0.20-2.00 mass%) and controls nitrogen concentration in the surface layer to achieve improved seizure resistance with controlled torque loss
3Reliability
If the bearing uses conventional materials and designs, then manufacturing cost is low, but seizure resistance and life are insufficient under high load and foreign substance conditions
Solution Approach 1:
The patent creates a composite structure with a nitrogen-rich surface layer on the bearing components, combining the base steel material with nitrogen enrichment to achieve enhanced seizure resistance and durability while maintaining manufacturing feasibility through controlled material composition
Solution Approach 2:
The patent modifies the chemical composition parameters within commercially available material ranges, allowing the use of standard manufacturing processes while achieving improved performance through optimized material properties
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces torque loss, improves seizure resistance, and increases the life of the bearing by enhancing the durability of contact surfaces and reducing lubricating oil retention, while maintaining cost-effectiveness and global material availability.
Implementation Method 1
a nitrogen concentration in a surface layer portion under a contact surface in contact with another component is 0.3 mass% or more
Data Source
Figure 1
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Figure 3
AI summary
A tapered roller bearing (1A) includes an outer ring (11), an inner ring (12), a plurality of tapered rollers (13), and a holder (20). The outer ring (11), the inner ring (12) and the tapered roller (13) each are made of steel containing 0.6 mass% or more and 1.50 mass% or less of carbon, 0.15 mass% or more and 2.50 mass% or less of silicon, 0.30 mass% or more and 1.50 mass% or less of manganese, and 0.20 mass% or more and 2.00 mass% or less of chromium, with the rest made up of impurities. A nitrogen concentration in a surface layer portion under a contact surface is 0.3 mass% or more. The holder (20) includes a small annular portion, a large annular portion, and a plurality of column portions. A pocket has a trapezoidal shape in which a portion housing a small diameter side of the tapered roller (13) is located on a reduced width side while a portion housing a large diameter side of the tapered roller (13) is located on an increased width side. Each of the column portions on the reduced width side of the pocket is provided with a cutout.