Rocker Arm Latching Arrangement Bore Manufacturing
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Solution Overview
Problem
The existing rocker arm designs for internal combustion engines face challenges in manufacturing due to the geometric relationship between the socket and lock pin bore, leading to frequent tooling breakage and increased costs, particularly in forming the oil supply bore with a small diameter and long length.
Innovation Solution
The rocker arm incorporates a latching arrangement with a connecting bore, oil supply bore, lock pin bore, and a retainer that provides fluid communication between the oil supply bore and lock pin bore, allowing for improved manufacturability and reducing tooling breakage by eliminating the need for the oil supply bore to intersect with the lock pin bore, thus enabling a more manageable tooling length-to-diameter ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the oil supply bore is formed to intersect with the lock pin bore due to geometric relationship between socket and lock pin bore, then the rocker arm can be assembled, but tooling breakage occurs frequently and manufacturing costs increase
Solution Approach 1:
A retainer is introduced as an intermediary component that provides fluid communication between the oil supply bore and lock pin bore. The retainer acts as a mediator that eliminates the need for the bores to intersect directly, allowing each bore to be formed independently with manageable tooling lengths while still achieving the required fluid communication function.
Solution Approach 2:
The fluid communication path is segmented into separate sections: the oil supply bore, the retainer with internal fluid passage, and the lock pin bore. This segmentation allows each component to be manufactured independently with simpler, shorter tooling rather than requiring a single long intersecting bore, thereby reducing tooling breakage risk.
2Ease of manufacture
If the oil supply bore has a small diameter and long length to connect socket to lock pin bore, then fluid communication is achieved, but tooling breakage becomes frequent
Solution Approach 1:
The long oil supply bore is segmented by introducing a retainer component that carries its own internal fluid passage. This divides the original long bore into two shorter sections, each manageable by standard tooling, eliminating the need for excessively long drill bits or taps that are prone to breaking.
Solution Approach 2:
The retainer serves as an intermediary component with an internal fluid passage that connects the oil supply bore and lock pin bore. This intermediary structure allows the use of shorter, more robust tooling for forming each bore separately, rather than requiring a single long tool to create an intersecting bore through the entire assembly.
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 design enhances manufacturing efficiency and reduces costs by simplifying the manufacturing process and minimizing tool breakage, while ensuring proper functionality by maintaining the decoupled and coupled states of the rocker arm.
Implementation Method 1
a retainer within the connecting bore which defines a chamber within the connecting bore which provides fluid communication between the oil supply bore and the lock pin bore
Implementation Method 2
One end of the lock pin is moved into and out of engagement with the inner arm. Consequently, when the lock pin is engaged with the inner arm, the coupled state is achieved. Conversely, when the lock pin is not engaged with the inner arm, the decoupled state is achieved. As shown in U.S. Pat. No. 7,305,951 to Fernandez et al., the other end of the lock pin acts as a piston upon which pressurized oil is applied and vented to affect the position of the lock pin
Data Source
AI summary
A rocker arm includes an outer arm; an inner arm which selectively pivots relative to the outer arm; and a latching arrangement which switches the rocker arm between a coupled state and a decoupled state. The latching arrangement includes a connecting bore which is terminated by a connecting bore floor; an oil supply bore which opens into the connecting bore through the connecting bore floor; a lock pin bore which opens into the connecting bore through the connecting bore floor; a lock pin within the lock pin bore where the lock pin prevents the inner arm from pivoting in the coupled state and where the lock pin permits the inner arm to pivot in the coupled state; and a retainer within the connecting bore which defines a chamber within the connecting bore which provides fluid communication between the oil supply bore and the lock pin bore.