Systematic Search with Physical Principles

For a given functional model of a product, product functions are connected by flows of materials, energies, and signals (information). Each function transforms a flow or set of flows to a new state. This transformation represents a physical process that is governed by physical principles.

Instead of relying on intuitive methods exclusively, we can state possible physical principles that can govern a product function or set of functions. Suppose we have a known physical effect described by a known equation. Then we know the number and type of independent variables. These variables can be studied closely to generate concepts based on variation of each parameter in a methodical way.

Example

Consider the function of "sense rotational speed" for a product application. A possible physical effect that can apply is a capacitive parallel plate system, governed by the relationship:

Figure 10.9 illustrates a systematic search of the variables that can change the capacitance. A change of voltage will result from any of the variable changes. The magnitude of this change represents the detected quantity by the product function.

Three variants are considered. The first varies the distance, d, between the plates. This displacement is inversely proportional to the capacitance, C. By considering this change, we arrive at solutions that are equivalent to microphone transducers. The second variable is the material property, B, between the two plates. If we gradually introduce a solid between the two plates (Figure 10.9), the voltage, e, changes, as detected by a change in capacitance. This change is equivalent to slot effect transducers. The third variable is the incident area, A, of the plates. By moving one plate relative to the other, the area changes, resulting in a voltage change. This change can represent reciprocating or rotational changes of the input on the upper plate (Figure 10.9). We then have an idea for a rotational detection device to satisfy the product function. This device is a capacitive tachometer (when combined with a processor that records and calculates the change as a function of time).

Date: 2016-01-14; view: 762