Drum Brake Electric Parking Actuator Cable Nesting
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Solution Overview
Problem
The existing drum brake type electric parking brake apparatuses face challenges in achieving smooth braking and release due to the limited length of the cable, which affects the flexibility and efficiency of the expanding mechanism, leading to increased complexity and cost when trying to absorb the difference between linear and arcuate movements.
Innovation Solution
The apparatus incorporates a pulling pipe with a male screw, a feeding nut with a female screw, and a connecting unit featuring a compression spring and spring cover to ensure the cable's length is maximized, allowing for smoother operation by absorbing the difference between linear and arcuate movements, thereby enhancing the flexibility of the cable and maintaining consistent braking force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cable length is increased to improve flexibility and smooth operation, then the braking smoothness is improved, but the device complexity increases due to the need for additional mechanisms to absorb movement differences
Solution Approach 1:
The cable is nested within the pulling pipe, allowing the cable to move freely inside the pipe while the pipe itself moves linearly. This nested configuration absorbs the difference between linear and arcuate movements without requiring additional complex mechanisms, thereby improving braking smoothness while maintaining structural simplicity.
Solution Approach 2:
The pulling pipe acts as an intermediary between the feeding screw and the cable. It converts the linear movement from the feeding screw into a guided path for the cable, allowing the cable to achieve sufficient length and flexibility for smooth arcuate movement at the connector without requiring complex absorption mechanisms.
2Ease of operation
If the cable length is increased to ensure flexibility for arcuate movement, then the operational smoothness is improved, but the cable cannot be made long enough without affecting the compactness and efficiency of the actuator unit
Solution Approach 1:
The cable is nested within the pulling pipe, which itself is contained within the actuator case. This nested arrangement allows the cable to be sufficiently long for flexibility and arcuate movement while the entire assembly remains compact. The pulling pipe serves as a protective sleeve that guides the cable without occupying additional external space.
Solution Approach 2:
The cable is allowed to move not only in the axial direction (linear movement from feeding screw) but also in the radial direction (arcuate movement at connector). This multi-dimensional movement capability enables the cable to achieve the necessary flexibility and length for smooth operation without increasing the overall volume of the actuator unit.
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 ensures a longer cable length, improving the flexibility and maintaining consistent braking force, allowing for smooth engagement and disengagement of the braking mechanism, reducing the likelihood of braking force drop and enhancing operational ease.
Implementation Method 1
a male screw formed on the outer circumferential surface of a rod 7 is threadedly engaged with the female screw of the screw pipe 6
Implementation Method 2
a compression spring 29 and a spring cover 30 surrounding the compression spring 29
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A drum brake type electric parking brake apparatus includes an electric actuator unit (1a) configured to pull a cable (8a) so as to expand an expanding mechanism (25), a pulling pipe (20) into which the cable (8a) is loosely inserted and supported so as to move in an axial direction, a feeding nut (21) supported so as to move in only a rotation direction and provided with a female screw (24) which is engaged with a male screw (23) on the pulling pipe (20), and a connecting unit (22) connecting a base end (27) of the pulling pipe (20) and a base end (28) of the cable (8a) so as to pull the cable (8a) in a direction away from the expanding mechanism (25) with the pulling pipe (20). The base end (28) of the cable (8a) is projected from the base end (27) of the pulling pipe (20) which is an end opposite to the expanding mechanism (25).