Piston Pump Roller Tappet Thermal Stress Reduction
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Solution Overview
Problem
Piston pumps with roller tappets face reduced service life and efficiency due to thermal stresses under temperature loads, leading to poor smooth running.
Innovation Solution
The piston pump features a roller tappet with a first bearing eye having a recess forming a continuous slot, making it more elastic than the second bearing eye, allowing the bolt and roller shoe to expand without inducing excessive stress, thus reducing thermal stresses and enhancing the pump's service life and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the first bearing eye is made more elastic by forming a recess, then thermal stress on components is reduced, but the structural strength and rigidity of the bearing eye are reduced
Solution Approach 1:
The recess is formed only in the first bearing eye, not uniformly across both bearing eyes. This creates a local difference in stiffness where the first bearing eye becomes more compliant to thermal expansion while the second bearing eye maintains higher rigidity for structural support. The selective modification resolves the contradiction by applying the elasticity enhancement only where thermal stress accommodation is needed.
Solution Approach 2:
The first bearing eye is segmented by the recess into two separate bearing legs. This segmentation allows the bearing eye to deform more easily under thermal load while maintaining overall structural integrity through the connection between the two legs. The segmented structure provides both the needed compliance for thermal expansion and sufficient strength for load bearing.
2Duration of action of stationary object
If the first bearing eye is made more elastic to accommodate thermal expansion, then service life is increased, but the precision and stability of the roller tappet are reduced
Solution Approach 1:
The asymmetric design where only the first bearing eye has a recess creates a gradient of stiffness that allows controlled deformation. The second bearing eye without a recess serves as a stable reference point, maintaining precision while the first bearing eye absorbs thermal expansion stresses, thereby extending service life without sacrificing overall stability.
3Object-affected harmful factors
If the recess is formed as a continuous slot separating the bearing legs, then thermal expansion compensation is maximized, but the manufacturing complexity and structural integrity are increased
Solution Approach 1:
The continuous slot recess creates a porous-like structure in the bearing eye by removing material along a continuous path. This porous configuration maximizes the compliance of the bearing eye for thermal expansion compensation while the remaining material structure maintains sufficient structural integrity. The slot geometry provides optimal balance between compliance and strength.
Solution Approach 2:
The recess geometry parameters (depth, width, orientation of the slot) can be optimized to achieve the desired balance between thermal expansion compensation and structural integrity. By adjusting these parameters, the bearing eye's compliance can be tuned without requiring complex manufacturing processes, as the slot can be formed using standard machining or casting techniques.
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
The design significantly reduces thermal stresses, increasing the service life and efficiency of the piston pump, ensuring smooth operation even under high temperature gradients, particularly in high-pressure fuel injection systems.
Implementation Method 1
the bolt and the roller shoe can undergo different thermal expansions without inducing excessive stress in the components
Implementation Method 2
the first bearing eye is more elastic than the second bearing eye
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a reciprocating pump (1) comprising a roller tappet (2) and a pump plunger (10) that is operatively connected to the roller tappet (2). The roller tappet (2) has a roller support (3), a roller (4) and a pin (5). A first bearing eye (6) and a second bearing eye (7) are formed in the roller support (3), the pin (5) being supported in the first bearing eye (6) and in the second bearing eye (7). The roller (4) is rotatably mounted on the pin (5). The pin (5) is mounted more resiliently in the first bearing eye (6) than in the second bearing eye (7).