Piezoelectric Cam Tappet Force Sensor
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Solution Overview
Problem
Direct measurement of cam and tappet contact force in internal combustion engines is challenging due to the narrow working space and complex motion between the cam shaft and tappet, making conventional measurement methods difficult, especially with strain gauges being hard to arrange on the tappet.
Innovation Solution
A sensor comprising a force carrying element, a piezoelectric element, a force bearing element, and a tappet head, with a guide woodruff key and wire outlet holes, designed to measure the contact force using a piezoelectric effect, allowing for the measurement of force magnitude and direction without interfering with other engine parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement means such as strain gauges are used, then measurement capability is provided, but they are difficult to arrange on the tappet due to narrow working space
Solution Approach 1:
The patent introduces a force transmission element as an intermediary between the tappet and the piezoelectric element. This mediator transfers the contact force from the difficult-to-access tappet to the easily measurable piezoelectric element, enabling force measurement without directly mounting sensors on the tappet itself.
Solution Approach 2:
The patent replaces the traditional strain gauge-based mechanical measurement system with a piezoelectric sensing system. The piezoelectric element converts mechanical force directly into electrical signals, providing a more suitable measurement approach for the narrow working space between cam and tappet.
2Measurement precision
If sensors are arranged on other transmission parts, then measurement is possible, but contact force must be indirectly calculated through stress relation
Solution Approach 1:
The patent extracts the force measurement function from the complex stress relation calculations by introducing a dedicated force transmission element and piezoelectric sensor. This separates the measurement function from the mechanical transmission system, enabling direct force measurement without indirect calculations.
Solution Approach 2:
The patent changes the measurement parameter from indirect stress relation calculations to direct piezoelectric charge output. The piezoelectric element provides a direct electrical signal proportional to the applied force, eliminating the need for complex stress analysis and parameter transformations.
3Measurement precision
If direct measurement of cam and tappet contact force is implemented, then accurate force data is obtained, but the narrow working space and complex motion create measurement difficulties
Solution Approach 1:
The patent segments the measurement system into distinct functional components: a force carrying element that experiences the contact force, a force transmission element that transfers the force, and a piezoelectric element that measures the force. This segmentation allows each component to be optimized for its specific function while working together in the narrow space.
Solution Approach 2:
The patent measures force in multiple dimensions by capturing both the magnitude and direction of contact force. The piezoelectric element, with its specific orientation and mounting configuration, enables measurement of force components in different directions, transforming a single-point measurement into a multi-dimensional force analysis.
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
Enables accurate measurement of cam and tappet contact force in normal, tangential, and axial directions, providing real and convincing results while maintaining normal engine operation without affecting the valve mechanism.
Implementation Method 1
a piezoelectric element, arranged between the force bearing element and the force transmission element
Data Source
AI summary
The present disclosure provides a sensor for measuring cam and tappet contact force of an engine and a measuring method. The sensor comprises a force carrying element, a force transmission element, a piezoelectric element, a force bearing element, a tappet head and a guide woodruff key. Meanwhile, the present disclosure also provides a measuring method by using the sensor. The sensor is simple in mechanism and convenient to use and can realize the measurement of the cam tappet contact force in the normal direction, the tangential direction and the axial direction of the contact surface.