Cam Elevation Curve Design for Piston Pump Speed and Oscillation
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Solution Overview
Problem
Cam-driven high-pressure pumps face challenges in achieving high ceiling speed while minimizing kinematic oscillation excitation of the pump element spring, as existing cam elevation curves either lead to high excitation frequencies or limited ceiling speed due to harmonic oscillations.
Innovation Solution
The cam elevation curve is modified by superposing a sine wave with twice the frequency and lower amplitude onto a basic sine wave, resulting in increased piston acceleration at the beginning of the upward stroke and decreased deceleration at the end, avoiding harmonic oscillations and allowing for higher ceiling speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cam elevations are composed of different subsections (tangent elevations or circular arcs) to reach high ceiling speeds, then ceiling speed is improved, but kinematic oscillation excitation increases due to kinks in acceleration curves causing high-order harmonic oscillations
Solution Approach 1:
The invention changes the mathematical parameters of the cam elevation curve by using a superposition of sinusoidal functions instead of traditional geometric sections. This allows continuous acceleration curves without kinks, eliminating harmonic oscillations while maintaining high ceiling speeds through optimized sine wave combinations.
Solution Approach 2:
The cam elevation curve is constructed as a composite function combining multiple sinusoidal components with different frequencies and amplitudes. This composite approach allows the curve to achieve both smooth transitions (reducing oscillations) and high peak velocities (increasing ceiling speed) that cannot be achieved with single geometric sections.
2Object-generated harmful factors
If sinusoidal cam elevations are used to minimize oscillation excitation of the pump element spring, then kinematic oscillation excitation is reduced, but ceiling speed is limited
Solution Approach 1:
The invention modifies the standard sinusoidal cam elevation by changing its parameters through superposition with additional sinusoidal functions. This transforms the simple sine wave into a more complex periodic function that maintains the smoothness needed to reduce oscillations while introducing features that enable higher ceiling speeds.
Solution Approach 2:
The cam elevation curve merges multiple sinusoidal functions with different characteristics into a single composite curve. This combination allows the beneficial properties of sinusoidal motion (smooth acceleration) to be preserved while adding capabilities for higher speeds that a single sine wave cannot provide.
Data Source
AI summary
In a device for driving a piston pump, including at least one cam (10) mounted on a camshaft (4) and cooperating with the pump piston (3), or a component arranged between the cam (10) and the pump piston (3), to generate a reciprocating movement of the pump piston (3), wherein the cam (10) has a cam elevation curve (15, 18) with a first section for the upward stroke and a second section for the downward stroke, the cam elevation curve (15, 18), departing from a shape substantially corresponding to that of a sine wave (14, 19), is modified in a manner that, in comparison to the shape of a sine wave (14, 19), an increase in the piston acceleration occurs at the beginning of the upward stroke and a decrease of the piston deceleration occurs at the end of the upward stroke.