//Logo Image
Author: Yung-Chieh Hung (2007-07-12); recommendation: Yeh-Liang Hsu (2007-07-12).
Note: This article is Chapter 6 of Yung-Chieh Hung’s PhD thesis “Development of an Innovative Patent-based Design Methodology.”

Chapter 6. Designing around multiple patents

Chapter 4 and Chapter 5 describe the process of designing around one patent. The process of designing around multiple patents is proposed in this chapter. Design of a magnetic impact tool is used an example to demonstrate the implementation.

6.1 Patent analysis

As discussed in Chapter 4, the designer first conducts standard patent search and analysis to identify the related patents to be designed around and to collect functions and core techniques of each related patent. After patent search and screening in the magnetic impact tool example, three patents (U.S. Patent 6,918,449, JP 09,254,046 and JP 2004,291,136) which achieve the functions “tighten/loosen screw”, “generate impact torque” and “change magnetic flux” are selected to be designed around.

The next step is reading and analyzing each concerned patent to develop the abstract lists of patents. The U.S. Patent 6,918,449 has been described in Chapter 4. Table 6-1 and Table 6-2 show the abstract lists of JP 09,254,046 and JP 2004,291,136.

Table 6-1. The abstract list of JP 09,254,046

Title

Power driver

Patent No.

JP 09,254,046

Date of field

1996/3/26

Date of issued

1997/9/3

Assignee

Matsushita Electric Works, Ltd.

Inventors

Shimizu Hideki

Tanaka Naotake

Analyst

David Hung

Keywords

magnetic, impact, rotate

IPC

B25B 23/157

B25B 23/14

Date of analysis

2007/6/1

Background of the invention

This invention relates to the electric driver equipped with the moderation device and the clutch device which will intercept driving force if it becomes setting torque and in which torque adjustment is possible between the motor for a drive, and an output shaft.

Functions of the patent

l          Tighten/ loosen screw

l          Generate impact torque

l          Change magnetic flux

Results of the patent

To eliminate wear, vibration, and noise due to impact and obtain large torque even if attractive force of magnets is small by constituting a clutch mechanism by a magnet clutch and arranging the magnet clutch between a motor and a decelerator.

Means for solution, composition and important figures

l          A motor 1 as a power source and a gear case 3 are connected mutually by a mounting base 2, and a pin which is an output shaft of the motor 1 and an input shaft 1a of a transmission part in the gear case 3 which is a shaft 31 on driving side is press-fitted in a magnet clutch 6 and is fixed. The magnet clutch 6 consists of a magnet mounting plate 6a which fits and fixes the input shaft 1a, magnets 6b, 6c which are magnetized in such a manner that they form different poles alternately in the direction of a face of a disc which constitutes a clutch plate 33 on driving side and a clutch plate 34 on output side, and a magnet mounting plate 6d. By arranging the magnet clutch 6 between a reducer 20 and the motor 1, transmission torque is reduced, and attractive force of magnets is reduced even when large torque is obtained in output.

Figure (a). JP 09,254,046

Independent claims

l          The electric driver characterized by arranging the electro magnetic clutch between a motor and a reducer while being the electric driver equipped with the clutch device which intercepts driving force and making a clutch device into an electromagnetic clutch, if it becomes setting torque while having a reducer between the motor for a drive, and an output shaft.

Table 6-2. The abstract list of JP 2004,291,136

Title

Magnetic impact tool

Patent No.

JP 2004,291,136

Date of field

2003/3/26

Date of issued

2004/10/21

Assignee

Matsushita Electric Works, Ltd.

Inventors

Sekino Fumiaki
Shinagawa Takeshi
Nakayama Satoshi

Analyst

David Hung

Keywords

magnetic, impact, rotate

IPC

B25B 21/02

Date of analysis

2007/6/1

Background of the invention

This invention relates to the technique in which it enables it to change transfer torque easily according to an object while abolishing generating of the impulsive sound in an impact tool.

Functions of the patent

l          Tighten/ loosen screw

l          Generate impact torque

l          Change magnetic flux

Results of the patent

To reduce noise by transmitting torque from a hammer to an anvil without contact, and further easily change the transmitted torque according to an object.

Means for solution, composition and important figures

l          This magnetic impact tool includes a drive shaft 5 to be rotatably driven by a motor 3, a magnetic hammer 21 to rotate together with the shaft 5, a magnetic anvil 11 provided on the outer periphery of the magnetic hammer 21, and an output shaft 16 to rotate together with the magnetic anvil 11. The impact tool has a magnetic pole formed on one of opposite surfaces of the hammer 21 and the anvil 11, and a magnetic pole or a magnetic substance formed on the other surface, and is constituted so that the rotation of the magnetic hammer 21 magnetically causes impact rotation force without contact. The tool also includes a gap changing means 50 for changing a radial gap 9 between the magnetic anvil 11 and the magnetic hammer 21.

 

Figure (a). JP 2004,291,136

Independent claims

l          A motor for generating rotational force.

l          A drive shaft rotatably driven by the motor.

l          A magnetic hammer rotatably moved in a coupled state with the shaft.

l          A magnetic anvil which faces the magnetic hammer and to which the rotational force is transmitted by magnetic coupling, with one of the opposing surfaces of the magnetic hammer and magnetic anvil having a magnetic pole, and the other having a magnetic pole or magnetic body.

l          An output shaft rotated by the magnetic anvil.

l          A gap changing means for changing a radial gap between the magnetic hammer and magnetic anvil.

The technology/function matrix is constructed for each concerned patent. Table 6-3 to 6-5 show the technology/function matrices of JP 09,254,046, JP 2004,291,136 and U.S. Patent 6,918,449.

Table 6-3. Technology/function matrix of JP 09,254,046

           Functions

Technologies

Tighten/ loosen screw

Generate impact torque

Change magnetic flux

Motor

 

Electromagnetic clutch

Output shaft

 

 

Reducer

 

 

Table 6-4. Technology/function matrix of JP 2004,291,136

           Functions

Technologies

Tighten/ loosen screw

Generate impact torque

Change magnetic flux

Motor

 

Drive shaft

 

Magnetic hammer

 

Magnetic anvil

 

Output shaft

 

 

Gap changing means

 

 

Table 6-5. Technology/function matrix of U.S. Patent 6,918,449

           Functions

Technologies

Tighten/ loosen screw

Generate impact torque

Change magnetic flux

Motor

 

Drive shaft

 

Magnetic hammer

 

Magnetic anvil

 

Output shaft

 

 

Magnetic bypass device

 

 

Changing device

 

 

6.2 Design matrix representation

In the “technology/function” matrix in Table 6-3 to 6-5, the “technologies” resemble the design parameters (DPs), and the “functions” resembles the functional requirements (FRs). In these three cases, they all have the same functions as follow:

= Tighten/ loosen screw

        = Generate impact torque

        = Change magnetic flux

In JP 09,254,046, the corresponding DPs are:

        = Motor

        = Electromagnetic clutch

        = Output shaft

        = Reducer

The technology/function matrix in Table 6-3 can be expressed as

                                                 (6.1)

                                                                                         (6.2)

where  is the transformation matrix which transfers the DRs into FRs.

In JP 2004,291,136, the corresponding DPs are:

        = Motor

        = Drive shaft

        = Magnetic hammer

        = Magnetic anvil

        = Output shaft

        = Gap changing means

The technology/function matrix in Table 6-4 can be expressed as

                                    (6.3)

                                                                            (6.4)

Finally, in U.S. Patent 6,918,449, the corresponding DPs are:

        = Motor

        = Drive shaft

        = Magnetic hammer

        = Magnetic anvil

        = Output shaft

        = Magnetic bypass device

        = Changing device

The technology/function matrix in Table 6-5 can be expressed as

                               (6.5)

                                                                       (6.6)

6.3 Assigning priority to DPs to be designed around

In order to assign priority to DPs to be designed around, a “uniform design matrix Au is introduced in this process. In the uniform design matrix Au, all DPs in the concerned patients are included. For example, in the 3 patents described in section 6.3, all DPs are renumbered as follows:

        = Motor (,  and )

        = Drive shaft ( and )

        = Magnetic hammer ( and )

        = Magnetic anvil ( and )

        = Output shaft (,  and )

        = Magnetic bypass device ()

        = Changing device ()

        = Gap changing means ()

        = Electromagnetic clutch ()

        = Reducer ()

Therefore, the JP 09,254,046 can be expressed as

               (6.7)

where

                                                     (6.8)

And the JP 2004,291,136 can be expressed as

              (6.9)

where

                                                    (6.10)

Finally, the U.S. Patent 6,918,449 can be expressed as

              (6.11)

where

                                                    (6.12)

Notice that Au2 is similar to Au3. The only difference is the components used to achieve function . These 3 patents are all belong to Matsushita Electric Works. This company adopts the method of “patent portfolio” to apply related patents about “magnetic impact tool”.

In order to assign priority to DPs to be designed around, the 3 uniform design matrices are summed to represent the appearance frequency of the components in the concerned patents. For example, in this case

                                (6.13)

DPs appearing in many patents are often fundamental components of the patents, such as motor () and output shaft () in Equation (6.13). It is difficult to design around these DPs. The priority of DPs to be designed around is given to those DPs appearing in fewest patents. Therefore, if a DP appears in only one patent, such as components , , ,  and , it has the highest priority to be designed around. If a DP appears in two patents, such as components ,  and , it has the second highest priority.

For DPs appearing in the same patent, as discussed in Section 5.3, the priority of DPs to be designed around is given to those having the least contribution to the FRs, and the DPs having minimal interaction with other DPs. The same sorting process discussed in Section 5.3 is used to assign priorities to the DPs.

For example, in Equation (6.7),  contributes to 3 functions ,  and , and  contributes to 1 functions .  interacts with 3 DPs (,  and ), while  also interacts with 3 DPs (,  and ) to achieve function . Therefore,  has the highest priority to be designed around, and  has the second highest priority to be designed around.  and  appear in 3 patents at the same time, so they are considered lastly. The same applies to JP 2004,291,136 and U.S. Patent 6,918,449.

According to these rules, the priorities of DPs to be designed around are as follows:

l          1st priority:  (gap changing means) and  (reducer)

l          2nd priority:  (magnetic bypass device) and  (changing device)

l          3rd priority:  (electromagnetic clutch)

l          4th priority:  (drive shaft),  (magnetic hammer) and  (magnetic anvil)

l          5th priority:  (output shaft)

l          6th priority:  (motor)

6.4 Design around operation

After the priorities of DPs are decided, the “design around operation matrix” D discussed in Chapter 5.4 is applied to the design matrix to generated a new design matrix :

                                                                                                 (6.14)

In this section,  (gap changing means) and (reducer), which were assigned the highest priority, are to be designed around.  (reducer ()) is considered first. Equation (6.15) shows the design matrix representation of JP 09,254,046 after sorting,

                                                 (6.15)

For elimination, let

                                                                                                (6.16)

        D1=                                                                                (6.17)

                                                                       (6.18)

Clearly , because  has been eliminated, and the designing around is successful according to the all element rule. The new design can be expressed as

                                                 (6.19)

                                                                      (6.20)

As shown in Equation (6.20), there is a new design problem to be solved (), which can be translated into:

l          Design problem 1: “How to design a transformation  to achieve the function  (tighten/ loosen screw) using components  (motor),  (electromagnetic clutch) and  (output shaft)?

For replacement, let

                                                                                  (6.21)

        D2=                                                                          (6.22)

                                                                        (6.23)

The technological characteristics of  must be different from those of , so that , and the designing around is successful according to the doctrine of equivalents. The new design can be expressed as

                                            (6.24)

                                                          (6.25)

As shown in Equation (6.25), there is a new design problem to be solved (), which can be translated into:

l          Design problem 2: “How to design a transformation  to achieve the function  (tighten/ loosen screw) using components  (motor),  (electromagnetic clutch),  (output shaft) and a new component , while the technological characteristics of  are different from those of .”

The design around operation matrix “decomposition” can also be applied to JP 09,254,046. After carrying similar process, a new design problem is generated as follow:

l          Design problem 3: “How to design a transformation  to achieve the function  (tighten/ loosen screw) using components  (motor),  (electromagnetic clutch),  (output shaft) and two new components  and , while the technological characteristics of  and  are different from those of .”

Design operation matrices can also be applied to  (gap changing means ()) of JP 2004,291,136. Two new design problems are generated:

l          Design problem 4: “How to design a transformation  to achieve the function  (change magnetic flux) using component , while the technological characteristics of  are different from those of .”

l          Design problem 5: “How to design a transformation  and two new components  and  to achieve the function (change magnetic flux) using two new components  and , while the technological characteristics of  and  are different from those of .” Note that, the technological characteristics of  and  also must be different from those of  and  of U.S. Patent 6,918,449; otherwise it may fall into the scope of doctrine of equivalents.

In the following section, TRIZ is used to find real engineering design concepts that solve these new design problems.

6.5 Generate real engineering design concepts using TRIZ

6.5.1 Solving design problem 4

In this section, the contradiction matrix and the inventive principles of TRIZ are used to solve these new design problems. For example,

Design problem 4: “How to design a transformation  to achieve the function  (change magnetic flux) using component , while the technological characteristics of  are different from those of .”

For design problem 4 described above, Parameter 10 (force) is selected as the feature for achieving the function of “changing magnet flux” by . In the mean time, we hope that it is easy for  to change magnetic flux. Therefore Parameter 33 (ease of operation) is selected as the feature not to be deteriorated in Table 6-1.

As shown in Table 6-1, four inventive principles can be obtained. They are Principle 1 (segmentation), Principle 28 (Mechanical interaction substitution), Principle 3 (local quality), and Principle 25 (self-service).

Table 6-1. The contradiction matrix

      Undesired result

 

 

Feature to change

1

33

39

Weight of moving object

Ease of operation

Productivity

1

Weight of moving object

 

 

 

 

 

 

 

 

 

 

10

Force

 

 

1, 28, 3, 25

 

 

 

 

 

 

 

39

Productivity

 

 

 

 

 

After reviewing the four principles, Principle 28 was utilized to generate the new concept in the portable magnetic impact tool. In TRIZ, Principle 28 has four explanations:

a.     Replace a mechanical system with an optical, acoustical, thermal or olfactory system.

b.     Use an electric, magnetic or electromagnetic field to interact with an object.

c.     Replace fields that are: stationary with mobile, fixed with changing in time, random with structured.

d.     Use fields in conjunction with ferromagnetic particles.

In particular, we decided to apply “use an electric, magnetic or electromagnetic field to interact with an object” to solve the new design problems.

In the new design concept, the new componentconsists of four solenoids. The four solenoids are mounted on the magnetic anvil, and the impact torque can be changed by varying the distribution ratio of the magnetic flux by operating a switch for setting the output of the electric current value. In this concept, the new component has already replaced the function of the gap changing means. This new design concept is the same as Section 5.5.1.

6.5.2 Solving design problem 2

Use design problem 2 in Section 6.4 as another example,

“How to design a transformation  to achieve the function  (tighten/ loosen screw) using components  (motor),  (electromagnetic clutch),  (output shaft) and a new component , while the technological characteristics of  are different from those of .”

For design problem 2 described above, Parameter 10 (force) is selected as the feature for achieving the function of “tighten/ loosen screw” by . In the mean time, we hope that the new component  is not too complicated. Therefore Parameter 26 (quantity of substance/ matter) is selected as the feature not to be deteriorated in Table 6-2.  

As shown in Table 6-2, four inventive principles can be obtained. They are Principles 14 (curvature increase), Principles 29 (pneumatics and hydraulics), Principles 18 (mechanical vibration), and Principles 36 (phase transitions).

Table 6-2. The contradiction matrix

Undesired result

 

 

Feature to change

1

26

39

Weight of moving object

Quantity of substance/ matter

Productivity

1

Weight of moving object

 

 

 

 

 

 

 

 

 

 

10

Force

 

 

14, 29, 18, 36

 

 

 

 

 

 

 

39

Productivity

 

 

 

 

 

After reviewing the three principles, Principle 29 was utilized to generate the new concept in the portable magnetic impact tool. In TRIZ, Principle 29 has an explanation:

a.     Use gas or liquid as parts of an object or system instead of solid parts.

In the new design concept, the new component  is a viscous fluid coupling. The coupling consists of a fan and a cylinder. The cylinder filled with a viscous fluid (for example, silicon oil) and the fan is put in the cylinder.

To transmit rotation from the drive shaft of electromagnetic clutch () to the output shaft (), the contact of fluid and fan cause the increase of frictional force, so the rotational speed of the output shaft can be reduced. This new component  can achieve the same function as reducer ().

Note that, the  (reducer) in JP 09,254,046 is an inscribed type planet reducer. In the new design concept,  is a viscous coupling. Therefore, the technological characteristics of  are different from those of , and the designing around is successful according to the doctrine of equivalents. Figure 6-1 shows the new design concept.

Figure 6-1. The new design concept of reducer (1)

6.5.3 Solving design problem 3

Use design problem 3 in Section 6.4 as another example,

Design problem 3: “How to design a transformation  to achieve the function  (tighten/ loosen screw) using components  (motor),  (electromagnetic clutch),  (output shaft) and two new components  and , while the technological characteristics of  and  are different from those of .”

For design problem 3 described above, Parameter 10 (force) is selected as the feature for achieving the function of “tighten/ loosen screw” by  and . In the mean time, we hope that the reduction ratio of the new reducer consists of  and  which is not fixed. Therefore Parameter 9 (speed) is selected as the feature not to be deteriorated in Table 6-3.

As shown in Table 6-3, four inventive principles can be obtained. They are Principle 13 (function reversal), Principle 28 (Mechanical interaction substitution), Principle 15 (dynamics), and Principle 12 (equivalence).

Table 6-3. The contradiction matrix

      Undesired result

 

 

Feature to change

1

9

39

Weight of moving object

Speed

Productivity

1

Weight of moving object

 

 

 

 

 

 

 

 

 

 

10

Force

 

 

13, 28, 15, 12

 

 

 

 

 

 

 

39

Productivity

 

 

 

 

 

After reviewing the four principles, Principle 15 and Principle 28 were utilized to generate the new concept in the portable magnetic impact tool. In TRIZ, Principle 15 has three explanations:

a.   Allow (or design) the characteristics of an object, external environment, or process to change to be optimal or to find an optimal operating condition.

b.  Divide an object into parts capable of movement relative to each other.

c.   If an object (or process) is rigid or inflexible, make it movable or adaptive.

In TRIZ, Principle 28 has four explanations:

a.     Replace a mechanical system with an optical, acoustical, thermal or olfactory system.

b.     Use an electric, magnetic or electromagnetic field to interact with an object.

c.     Replace fields that are: stationary with mobile, fixed with changing in time, random with structured.

d.     Use fields in conjunction with ferromagnetic particles.

In particular, we decided to apply “divide an object into parts capable of movement relative to each other” and “use an electric, magnetic or electromagnetic field to interact with an object” to solve the new design problems.

In the new design concept, a viscous coupling control device is composed of the new component and . The coupling consists of two half-couplings ( and ) enclosed in a casing filled with an electrorheological fluid. An electric field is applied to the electrorheological fluid. The changing electric field strength changes the viscosity of the electrorheological fluid in the coupling. The changing electrorheological fluid viscosity changes the slippage of half-coupling plates. Therefore, the reduction ratio can be adjusted. This makes it possible to smoothly control the speed of rotation of the output shaft.

In this concept, the technological characteristics of  and  are different from those of , and the designing around is successful according to the doctrine of equivalents. Figure 6-2 shows the new design concept.

Figure 6-2. The new design concept of reducer (2)