Crankshaft Counterweight Hydrodynamic Entry Reduces Oil Shocks
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Solution Overview
Problem
Existing crankshafts experience friction and shock issues with oil in the crankcase due to counterweight collisions, leading to emulsion phenomena, disrupted lubrication, and hydrodynamic losses, which prior solutions fail to adequately address.
Innovation Solution
The crankshaft features counterweights with a hydrodynamic shape extending over an angular sector greater than 20% of the entry and exit edges, configured to reduce shocks by using a bevel or oblique wall design, which helps in smoother entry and exit from the oil, thereby minimizing friction and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If counterweights are equipped with conventional shapes, then the crankshaft structure is simple and easy to manufacture, but the counterweights cause shocks and emulsion phenomena when entering and exiting the oil, disrupting lubrication and generating hydrodynamic losses
Solution Approach 1:
The counterweight is equipped with a curved entry edge instead of a sharp or flat edge. This curvature allows the counterweight to gradually enter the oil, reducing shock and minimizing emulsion phenomena. The curved geometry smoothly transitions the oil flow, decreasing hydrodynamic losses while maintaining effective lubrication.
Solution Approach 2:
The invention modifies the geometric parameters of the counterweight by introducing specific angular sectors (greater than 20% of the total counterweight angle) with curved entry edges. This parameter change optimizes the hydrodynamic interaction between the counterweight and oil, reducing shocks and energy losses without significantly complicating the manufacturing process.
2Reliability
If counterweights collide with oil during acceleration and braking, then the crankshaft can be simple in design, but emulsion phenomena occur which disrupt internal pressure and lubrication
Solution Approach 1:
The curved entry edge of the counterweight gradually displaces the oil during acceleration and braking, preventing sudden collisions that cause emulsion. This curvature maintains oil separation and prevents the formation of emulsions that would disrupt lubrication effectiveness and internal pressure.
Solution Approach 2:
The curved geometry of the entry edge anticipates the oil displacement that occurs during acceleration and braking. By designing the entry edge to smoothly enter the oil rather than abruptly, the design preemptively prevents the harmful emulsion phenomena before they can occur during dynamic operation.
3Loss of energy
If conventional counterweight designs are used, then manufacturing is straightforward, but shocks generate hydrodynamic losses that vary with oil fluidity
Solution Approach 1:
The curved entry edge can be manufactured using standard casting or forging processes with appropriate mold or die design. While slightly more complex than sharp edges, the curvature is achieved through conventional manufacturing techniques, maintaining ease of production while significantly reducing hydrodynamic losses.
Solution Approach 2:
The invention specifies that the curved entry edge should occupy greater than 20% of the counterweight's angular sector, providing a clear manufacturing parameter. This quantitative specification allows manufacturers to achieve the hydrodynamic benefits without requiring excessive complexity in the manufacturing process.
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 effectively reduces the impact of counterweights on oil, enhancing lubrication and cooling effects while minimizing hydrodynamic losses, thus improving the overall efficiency and performance of the heat engine.
Implementation Method 1
the shape configured to reduce shock gives the counterweight a hydrodynamic shape. It is for example obtained by stamping. It extends from the entry edge and towards the exit edge.
Implementation Method 2
the shape configured to reduce shock gives the counterweight a hydrodynamic shape... at least one oblique wall, which allows entry of the inlet edge into the oil limiting shocks.
Implementation Method 3
the entry edge and the exit edge are joined by a rounded edge, the shape extending from this rounded edge in the direction of the axis of rotation.
Data Source
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AI summary
The present invention relates to a crankshaft (1) of a heat engine extending along an axis of rotation (X) and comprising at least one crankpin (12) and two crank arms (16) each equipped with a counterweight (24) intended to be immersed at least partially in the oil of the heat engine, this counterweight (24) extending over an angular sector (α) between an inlet edge (32) in the oil and an outlet edge (34) of the oil. According to the invention, the counterweight (24) comprises at least one shape (40) configured to reduce shocks at the entry of the inlet edge (32) into the oil, said shape (40) extending over at least one face (36, 38) of the counterweight (24) secant from the axis of rotation (X) from the inlet edge (32) and over an angle (β) greater than 20% of the angular sector (α).