Example 2: Evolution of car suspension

Another Line of Increasing Flexibility is shown below:

Fig. 3

Principal points of evolution along both the Mono-Bi-Poly Line and Line of Increasing Flexibility can be illustrated by various designs of two systems as reflected in the U.S. patents: a) hair comb/brush and  b) varifocal lens system.

The principal developments of the comb/brush system were studied along two directions:

• Transition from a mono-system to a bi- and poly-system, i.e., combination of various hair treatment products in one product, and
• Increasing flexibility of both mono- and bi(poly)-systems.
  
  The principal development of varifocal lens systems were studied along the Line of Increasing flexibility.
  
  Let us consider transition of "mono" comb/brush to bi- (poly)-system first.

4.3.1 Transition to bi- and poly-system

Transition to a bi-system can take place not only at the level of the whole product (comb/brush), but at the level of its components as well. For example, a fluid-dispensing comb suggested in U.S Patent 5,337,764 can be considered as a logical advancement of the design in U.S. Patent 4,090,522. The former has two fluid reservoirs (for different hair treatment fluids) removably attached to the body such that fluid communication is provided from the reservoirs to the teeth.

As one can see the process of increasing flexibility also goes on both at the level of the whole comb/brush and at the level of its components. Here are several examples:

4.3.3 Increasing Flexibility of Bi-System

The described above steps of evolution of the hair comb/brush are not always aligned in a chronological order. This is typical for, practically, any technological system. Some pioneering patent can be granted a hundred years ahead of its time, and most of the patents/inventions/solutions appear rather chaotically. However, major developments fit into basic steps of the Lines of Evolution. Accordingly, these steps can be applied to an existing product/process in order to develop a continuum of potential evolutionary changes in its design/structure. This process represents the TRIZ technological forecasting, or Guided Technology Evolution.

The type of Conventional varifocal (zoom) lens systems that is most commonly found in practice is the multi-element glass lens system that is optically structured so that its focus can be varied by changing the axial air spacing between its elements through the use of movable mechanical lens mounts.

Another type of variable focus lens systems utilizes a pair of optical refracting plates having surfaces that are specifically configured to selectively define, in combination, spherical lenses having different focal lengths as the plates are displaced with respect to one another.

All conventional varifocal lens systems share common fundamental drawbacks:

• Considerable weight of and space occupied by numerous glass elements.
• Expensive and time-consuming manufacturing (i.e., grinding and polishing).

4.4.6. TRIZ analysis of the conventional varifocal lens systems

From TRIZ standpoint (Line of Increasing Flexibility), it is clear that the aforementioned drawbacks can be eliminated by transition from rigid lens systems based on glass elements (lenses and mirrors) to systems that may use elements made of other, more flexible materials.

The Line of Increasing Flexibility suggests that the lens systems should evolve through the following stages (Fig. 4):

1. One rigid glass lens
2. Two-lens varifocal system
3. Multi-lens varifocal system
4. Elastomeric varifocal lens system
5. Liquid varifocal lens system
6. Gas varifocal lens system
7. Varifocal lens system using various fields (first of all, fields of electromagnetic nature)

Analysis of both patent databases and R&D literature, performed by The TRIZ Group, corroborates to a large extent this assumption. Stages 1-3 are represented by the conventional lens systems. Varifocal lens systems corresponding to stages 4-6 can be found in many recent patents and publications. Varifocal lens systems of stage 7 are not developed yet.

Fig. 4

Typical elastic lens system

The variable focus lens system of this type comprises a lens element formed of at least one transparent, homogeneous elastomeric material that is shaped to provide it with a predetermined focus length when the lens element is in relaxed or nearly relaxed state.

There are means for supporting the lens element along and perpendicular to its optical axis and for applying radial tensile stress around the periphery of the lens element (as shown, for example, in U.S. Patent 4,444,471, Figs 2, 3)

Fig. 5

Fig. 6

The preferred embodiment of the variable focus lens system is shown in Fig. 5. The lens system comprises four major elements, an integrally formed, elastomeric optical member 12, a two-part clamp 20, a circular bezel 38, and a cylindrical tubular member 40. The optical member 12 is a three-part structure comprising a central lens element 14, a circular flexible membrane 16, and a circular toroidal edge 18. On the outer surface of the tubular member 40 there are two grooves 72 (Fig. 6) that are spaced 18--degrees apart into which slidabli fit a corresponding pair of tongues 30 extending forwardly parallel to the optical axis, OA, from the clam front section 22. Clockwise rotation of bezel 38 about axis OA causes the tubular member 40 to displace axially along axis OA, so that the forward edge of the tubular member 40, comprising the rollers 66, contacts the flexible membrane 16 at a predetermined radial distance away from the peripheral edge of the lens element 14. As the tubular member 40 is displaced along axis OA, it leading edge operates to apply a force to the flexible membrane 16 in the direction parallel to axis OA.. The radial stress thus created is uniformly distributed about the periphery of the lens element 14 and operates to alter its shape (Fig. 3), so that the focal length of the lens element 14 can be changed in a continuous manner.

In a typical fluid lens system (as suggested, for example, in U.S. Patent 4,466,706, Fig. 7), a variable shape/volume chamber is filled with an optically clear fluid, having a specified refraction coefficient, the pressure of which is regulated by adjusting the volume of the chamber. The latter is closed at opposite ends by resilient optically clear diaphragm elements that bend or budge with varying degrees of curvature responsive to pressure changes induced in the fluid.

Typically, a pair of axially adjustable telescoping sleeves defines a chamber. The opposite outer ends of the chamber are closed by a pair of relatively thin resilient optical discs formed of available plastic material. The discs alter their curvatures in response to changes in the fluid pressure.

Fig. 7

Typical gas lens system

In these systems, gas pressure changes correlate with movements of the lens through magnification changes. Changing the pressure of the high refraction index gas leads to changing the focal length of the gas lens, and, as a result, to changing the focal length of the whole lens assembly. Fig. 8 (as represented in U.S. Patent 4,732,458) is a schematic representation of a gas zoom lens 10. Lens 10 comprises a first lens group 22 (A, B) and a second lens group 24 (C, D). Separating the negative meniscus elements B, C is a cavity 26 filled with a heavy high refraction index gas. Connected to the cavity 26 is a piston/cylinder assembly 30. Piston 32 is adapted to move up and down within cylinder 34 raising or lowering, respectively, the pressure of the gas in the cavity 26.

Fig. 8

4.4.8 Major design problems of the non-conventional (fluid) varifocal lenses

There is a growing need for large telescopes, projection lenses, aerial camera lenses, satellite camera lenses, and concentrating lenses for solar energy devices that can be met by lenses formed by liquids and gases. Despite many potential uses of the latter (mostly, because of their low cost), they have two major design restrictions:

1. Waves and ripples resulting from vibrations introduced by the surrounding
   environment and/or mechanisms.
2. The varifocal lens must have a quick response to make it suitable for various applications. Quick response varifocal lenses can be designed by using a highly rigid material. However, because of the pressure applied to the operating liquid or gas, the use of transparent elastic films made of a rigid material results in the generation of harmful aberrations.

These problems are not overcome in the existing proposed designs.

4.4.9. TRIZ approach to resolving the design problems of the non-conventional
(fluid) varifocal lenses

From TRIZ standpoint, further promotion of the fluid varifocal lenses is possible by advancing their structure farther along the Line of Increasing Flexibility (Fig. 1). This suggests the following design changes:

1. To use magnetic and electric fields as means to control structural properties of fluid lenses.
2. To replace conventional optically clear fluids with optically clear fluids susceptible to magnetic and/or electric fields.
3. To use materials exhibiting non-linear mechanical/optical properties.

The traditional and TRIZ forecasts can be distinguished by their respective outcomes. A conventional technology forecast is concerned with calculating the probability that a particular parameter of the system of interest reaches certain level by the specified point in time. A TRIZ forecast results in developing of an array of design modifications of the system that may advance it along its S-curve.

Thus, the main benefits of the TRIZ forecasting are the following:

• TRIZ forecast means developing conceptual designs of new systems. In other words, TRIZ forecast shows not only what will happen, but also how to achieve the desirable results.
• Higher accuracy of the forecast, since it is based on the Laws of Technological Systems Evolution.
• Detection of the point in time when development of the present technology should be abandoned and new directions should be explored.

TRIZ forecasting consists of four major phases:

1. Analysis of the system's evolution
   
   Study of the history of the system and its position on its "life curve" (S-curve).
   

2. "Road mapping"
   
   Application of the Laws and Lines of Technological Systems Evolution to forecast functional and structural alterations in the system
   

3. Problem formulation
   
   Formulation of engineering problems to be solved so as to achieve targets set at the
   previous phase
   

4. Problem solving
   
   Solving the formulated problems by using powerful analytical and solution tools of TRIZ
   

6.1 Analysis of the system's evolution

Evolution of technological systems can be illustrated by an S-shaped (Fig. 9) curve reflecting changes of the system's benefit-to-cost ratio with time since the inception of the system. In phase 1 the system's development is relatively slow. Phase 2 features a fast development, usually associated with a commercial implementation of the system and perfecting of the manufacturing processes. Then the pace of development eventually slows down (phase 3) and stalls (phase 4). Sometimes the system enters phase 5 of degradation. In some cases, the system undergoes "renaissance" (phase 6), which can be sparked by availability of new materials, of new manufacturing technology, and/or by development of new applications. When system A in Fig. 9 is approaching the conclusive phases 3 and 4 of its development, usually a new system B having a higher performance potential is already waiting in the wings.

The length and slope of each segment on the system's life curve depends not only on technological but also on economic and on human factors. The common sense (in the hindsight!) suggests that a new system B in Fig. 9 should start its fast development when development of the system A begins slowing down. However, frequently development of system B is delayed by special interest groups which have large investments into the existing technology, job security, etc., associated with the old system.

Analysis performed by Altshuller demonstrated that inventive activity correlates closely with the S-curve. A typical function "number of inventions per unit time ?? time" for a system (Fig. 10) has two peaks. The first peak occurs near point a on the S-curve thus indicating the beginning of mass implementation of the new system. The second peak coincides with the end of the system's "natural life" (around point g ) and is associated with efforts (usually futile in the long run) to extend the system’s life, to compete with the new evolving system.

Fig. 11 shows the level of inventions at different stages of the system’s life. At the beginning, inventions creating the basis for a new system are usually of a high level (i.e., high degree of novelty). This level gradually declines and then rises again in the process of implementation of the system, when many problems associated with manufacturing and marketing must be solved. After this peak, the levels of inventions drop again.

Fig. 12 illustrates dynamics of change of average economic effectiveness of a technological system in different periods. The first inventions that lay foundation for the system , notwithstanding their high technical level, do not bring profit since the system exists only on paper as a promising concept. The rewards for the inventions grow in the course of implementation of the system. At the stages when the system is in mass production, even small improvements may result in significant economic rewards.

It is usually feasible to collect information needed to plot the above curves. Analysis of these curves helps one to determine position of the system of interest on its S-curve.

Three typical cases may exist:

1. The system has not progressed up to point , Fig. 9. Position of this point should be determined by forecasting the potential of the system as compared with the competing systems. The condition associated with point develops only when deterioration of the preceding system begins. The existing system deters development of the new competing system.
2. If the system evolves between points and , the forecast should determine physical limits of the system based on the objective factors (e.g., strength of materials, heat producing capacity of fuels, various barriers such as speed of sound for airplanes, manufacturing costs, etc.). An array of conceptual modifications of the system that may provide for its advancement up to point  and should be conceived.
3. The system has passed point  and (or point ). In this case, the forecasting process is, in
   essence, a search for a new system that may succeed the existing system.

6.2 "Road mapping"

After the history of the system's evolution and its position on S-curve have been established, the Laws and Lines of Evolution are applied to foresee (conceptually) the possible future designs of the system. Analysis of the state-of-the-art of the present system allows one to determine the current stage of the system’s evolution and identify the next stages. At this phase, application of various Lines of Evolution enables identification of the missing steps and feasible future steps of development.

As a rule, transition from one stage of evolution to the next stage is accompanied by formulation of design and/or production problems to be resolved. For example, the need to increase flexibility of a system by introducing electromagnetic field can contradict the requirement for the design simplicity. Thus, to make the next step in the system’s evolution, a conflict between increasing flexibility and design complexity has to be overcome.

Since the forecasting is carried out along several Lines of Evolution that represent different Laws, usually there are many engineering problems, which are to be formulated and resolved.

REFERENCES

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2. Altshuller, G.S., And Suddenly the Inventor Appeared, Technical Innovation Center,
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4. Fey, V., Fundamentals of the Theory of Inventive Problem Solving, Course Materials, Wayne State University, Detroit, 1998.
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   The TRIZ Group, 1997.
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