Rack Guide Geometry for Quiet Rack-and-Pinion Steering
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Solution Overview
Problem
The manufacturing process for rack guides in rack and pinion steering devices is complex and costly due to the need for high accuracy in forming complementary surfaces between the rack guide and its base member to ensure quiet operation.
Innovation Solution
The use of abutment surfaces made from resin, porous metal, or sintered alloy with distinct thickness dimensions for the abutment and recessed portions simplifies the manufacturing process and allows for a close contact property between the rack guide and its base member, reducing manufacturing costs while maintaining quietness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rack guide support surface is processed to have a shape complementary to the curbed surface of the rack guide to ensure close contact and quietness, then the contact accuracy between rack guide and base member is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the geometric parameters of the rack guide by providing a flattened portion on its outer peripheral surface. This flattened portion has a different thickness than the main body, creating a simplified planar contact surface. The rack guide base member is correspondingly designed with a matching planar contact surface, eliminating the need for complex complementary curbed surfaces while maintaining close contact and quiet operation.
2Manufacturing precision
If the rack guide support surface is processed to have a shape complementary to the curbed surface of the rack guide to ensure close contact and quietness, then the contact accuracy between rack guide and base member is improved, but the manufacturing cost increases
Solution Approach 1:
The invention simplifies the geometric parameters of the rack guide by introducing a flattened portion with uniform thickness. This design allows the rack guide base member to use a simple planar contact surface instead of a complex complementary shape. The simplified geometry reduces manufacturing steps, tooling requirements, and inspection complexity, thereby lowering manufacturing costs while ensuring close contact and quiet operation.
3Ease of operation
If a curbed surface with multiple curvature radiuses is used for the rack guide to prevent excessive sliding resistance, then the sliding performance is improved, but the manufacturing process becomes more difficult to simplify
Solution Approach 1:
The invention segments the rack guide into two distinct functional portions: a main body portion with a curbed surface for optimal sliding performance, and a flattened portion for simplified manufacturing and mounting. The curbed surface maintains the necessary curvature radiuses for preventing excessive sliding resistance, while the flattened portion provides a simple planar contact surface. This segmentation allows each portion to fulfill its specific function independently, resolving the contradiction between sliding performance and manufacturing simplicity.
Data Source
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AI summary
To provide a rack guide (103A1, 103, 303, 403, 4) for a rack and pinion steering device (101, 103), a rack and pinion steering device (101, 103) and a manufacturing method for a rack guide (103A1, 103, 303, 403, 4) for a rack and pinion steering device (101, 103), having a simple configuration with a close contact property being kept between a rack guide (103A1, 103, 303, 403, 4) and a rack guide base member (105, 107, 305) to ensure quietness. A rack guide (103A1, 103, 303, 403, 4) for a rack and pinion steering device (101, 103) comprising: a casing (107, 109); a pinion (109, 111) to be slidably supported by said casing (107, 109); a rack bar (111, 113, 11, 311) having a rack tooth meshed with said pinion (109, 111); a rack guide (103A1, 103, 303, 403, 4) comprising an abutment portion (103A1, 103A2, 103B1, 303A1, 303A2, 403A1, 403A2, 403A) to which said rack bar (111, 113, 11, 311) is to be slidably abutted and a recessed portion (103B1, 103B2, 105, 303B1, 303B2, 403B1, 403B2), which is continued to said abutment portion (103A1, 103A2, 103B1, 303A1, 303A2, 403A1, 403A2, 403A), to be spaced from said rack bar (111, 113, 11, 311); a rack guide base member (105, 107, 305) for receiving said rack guide (103A1, 103, 303, 403, 4); and urging means for urging said rack guide (103A1, 103, 303, 403, 4) against said rack bar (111, 113, 11, 311) through said rack guide base member (105, 107, 305), wherein a thickness (T1, T2) dimension of said recessed portion (103B1, 103B2, 105, 303B1, 303B2, 403B1, 403B2) is different from that of said abutment portion (103A1, 103A2, 103B1, 303A1, 303A2, 403A1, 403A2, 403A), a rack and pinion steering device (101, 103) thereof, and a rack guide (103A1, 103, 303, 403, 4) manufacturing method thereof.