To DMF or not to DMF on a M47R engine.

[MSS]

Originally Posted by alanaslan

I promise I will post the physics and maths as soon as I manage to get the desk top on to the form so I can cut and paste. I have never mastered the clever bits in the IPad, I am sure it can be done, but it is beyond me. Bring back DOS, Basic, Forth, and fortran, I could get my head around them in the eighties. But then I was in my forty’s. The common programs were WordPerfect, Lotus 123 and Paradox, All of which I could get to do what I wanted for some of the Paradox reports I had to use Twist and shout to landscape the reports. A lifetime ago.


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Fortran 77 was my favourite language, having used it to write a lot of signal processing software incldung FFT, digital filter design, speech encoding/decoding etc.

Modern languages make it too easy!

[alanaslan]

Originally Posted by MSS

In the same way that removing the DMF does, surely!

I have to say though that if you could cut a display window in the bell housing, a Kevlar lined clutch would look the part!

This brings back fond memories of building / hacking away parts of a Reliant 850cc engine for one of the Branches of their car club. The unit was a display engine driven by an electric motor through the ring gear. Acrylic components permitted a view of two of the cylinders from the crank shaft to valve gear the cut away at the rear gave a view of the push rods and the acrylic rocker cover let you see the valve gear operating . The bell housing was 50% cutaway again with an acrylic insert to allow the flywheel and clutch to be seen. The engine set up had no compression but did have a clear distributor and the ignition system had a power supply so the spark could be seen on the compression stroke prior to the power stroke.
I built this back in the Eighties, I wonder what ever happened to it.?
It let you see how a internal combustion engine worked, and was mounted in a rolling chassis from a Reliant Kitten. That was transported on top of a 6’x4’ trailer, round the car shows the Club attended for several years.


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[alanaslan]

Originally Posted by alanaslan

I promise I will post the physics and maths as soon as I manage to get the desk top on to the form so I can cut and paste. I have never mastered the clever bits in the IPad, I am sure it can be done, but it is beyond me. Bring back DOS, Basic, Forth, and fortran, I could get my head around them in the eighties. But then I was in my forty’s. The common programs were WordPerfect, Lotus 123 and Paradox, All of which I could get to do what I wanted for some of the Paradox reports I had to use Twist and shout to landscape the reports. A lifetime ago.


Sent from my iPad using Tapatalk

A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, if we assume the flywheel's moment of inertia to be constant (i.e., a flywheel with fixed mass and second moment of area revolving about some fixed axis) then the stored (rotational) energy is directly associated with the square of its rotational speed.
Since a flywheel serves to store mechanical energy for later use, it is natural to consider it as a kinetic energy analogue of an electrical inductor. Once suitably abstracted, this shared principle of energy storage is described in the generalized concept of an accumulator. As with other types of accumulators, a flywheel inherently smoothes sufficiently small deviations in the power output of a system, thereby effectively playing the role of a low-pass filter with respect to the mechanical velocity (angular, or otherwise) of the system. More precisely, a flywheel's stored energy will donate a surge in power output upon a drop in power input and will conversely absorb any excess power input (system-generated power) in the form of rotational energy.
Common uses of a flywheel include:

• Smoothing the power output of an energy source. For example, flywheels are used in reciprocating engines because the active torque from the individual pistons is intermittent.
• Energy storage systems
• Delivering energy at rates beyond the ability of an energy source. This is achieved by collecting energy in a flywheel over time and then releasing it quickly, at rates that exceed the abilities of the energy source.
• Controlling the orientation of a mechanical system, gyroscope and reaction wheel

Flywheels are typically made of steel and rotate on conventional bearings; these are generally limited to a maximum revolution rate of a few thousand RPM.[1] High energy density flywheels can be made of carbon fiber composites and employ magnetic bearings, enabling them to revolve at speeds up to 60,000 RPM (1 kHz).[2]

Flywheels are often used to provide continuous power output in systems where the energy source is not continuous. For example, a flywheel is used to smooth fast angular velocity fluctuations of the crankshaft in a reciprocating engine. In this case, a crankshaft flywheel stores energy when torque is exerted on it by a firing piston, and returns it to the piston to compress a fresh charge of air and fuel. Another example is the friction motor which powers devices such as toy cars. In unstressed and inexpensive cases, to save on cost, the bulk of the mass of the flywheel is toward the rim of the wheel. Pushing the mass away from the axis of rotation heightens rotational inertia for a given total mass.




References
· "Flywheels move from steam age technology to Formula 1". Archived from the original on 2012-07-03. Retrieved 2012-07-03.; "Flywheels move from steam age technology to Formula 1"; Jon Stewart | 1 July 2012, retrieved 2012-07-03
·· "Breakthrough in Ricardo Kinergy 'second generation' high-speed flywheel technology". 2011-08-21. Archived from the original on 2012-07-05. Retrieved 2012-07-03., "Breakthrough in Ricardo Kinergy ‘second generation’ high-speed flywheel technology"; Press release date: 22 August 2011. retrieved 2012-07-03
·· Lynn White, Jr., "Theophilus Redivivus", Technology and Culture, Vol. 5, No. 2. (Spring, 1964), Review, pp. 224–233 (233)
·· Letcher, Trevor M. (2017). Wind energy engineering: a handbook for onshore and offshore wind turbines. Academic Press. pp. 127–143. ISBN 978-0128094518. Ibn Bassal (AD 1038–75) of Al Andalus (Andalusia) pioneered the use of a flywheel mechanism in the noria and saqiya to smooth out the delivery of power from the driving device to the driven machine
·· Ahmad Y Hassan, Flywheel Effect for a Saqiya.
·· "Flywheel" (PDF). themechanic.weebly.com.
·· Shabbir, Asad. "The Role of Muslim Mechanical Engineers In Modern Mechanical Engineering Dedicate to12th Century Muslim Mechanical Engineer" (PDF). Islamic Research Foundation International, Inc.
·· Lynn White, Jr., "Medieval Engineering and the Sociology of Knowledge", The Pacific Historical Review, Vol. 44, No. 1. (Feb., 1975), pp. 1–21 (6)
·· Dunn, D.J. "Tutorial – Moment of Inertia" (PDF). FreeStudy.co.uk. p. 10. Archived (PDF) from the original on 2012-01-05. Retrieved 2011-12-01.
·· "Flywheels: Iron vs. Steel vs. Aluminum". Fidanza Performance. Archived from the original on 10 October 2016. Retrieved 6 October 2016.
·· Ashby, Michael (2011). Materials Selection in Mechanical Design (4th ed.). Burlington, MA: Butterworth-Heinemann. pp. 142–146. ISBN 978-0-08-095223-9.
·· Totten, George E.; Xie, Lin; Funatani, Kiyoshi (2004). Handbook of Mechanical Alloy Design. New York: Marcel Dekker. ISBN 978-0-8247-4308-6.
·· Kumar, Mouleeswaran Senthil; Kumar, Yogesh (2012). "Optimization of Flywheel Materials Using Genetic Algorithm" (PDF). Acta Technica Corviniensis-Bulletin of Engineering. Archived (PDF) from the original on 1 November 2015. Retrieved 1 November 2015.
·· "Flywheel Energy Storage, UPS, Battery-Free, Active Magnetic Bearing, Magnetic Bearings, Kinetic Energy, Magnet Motor Generator, Bi-Directional Power Converter - Calnetix". www.calnetix.com. Archived from the original on 1 November 2017. Retrieved 2 May 2018.
·· "Flywheel Energy Calculator". Botlanta.org. 2004-01-07. Archived from the original on 2011-07-25. Retrieved 2010-11-30.
·· "energy buffers". Home.hccnet.nl. Archived from the original on 2010-11-26. Retrieved 2010-11-30.
·· "Message from the Chair | Department of Physics | University of Prince Edward Island". Upei.ca. Archived from the original on 2010-04-30. Retrieved 2010-11-30.
·· "Density of Steel". Hypertextbook.com. 1998-01-20. Archived from the original on 2010-11-25. Retrieved 2010-11-30.
·· Flywheel Rotor And Containment Technology Development, FY83. Livermore, Calif: Lawrence Livermore National Laboratory , 1983. pp. 1–2
·· Li, Xiaojun; Anvari, Bahar; Palazzolo, Alan; Wang, Zhiyang; Toliyat, Hamid (2018-08-14). "A Utility Scale Flywheel Energy Storage System with a Shaftless, Hubless, High Strength Steel Rotor". IEEE Transactions on Industrial Electronics. 65 (8): 6667–6675. doi:10.1109/TIE.2017.2772205. S2CID 4557504.
·· Li, Xiaojun; Palazzolo, Alan (2018-05-07). "Multi-Input–Multi-Output Control of a Utility-Scale, Shaftless Energy Storage Flywheel With a Five-Degrees-of-Freedom Combination Magnetic Bearing". Journal of Dynamic Systems, Measurement, and Control. 140 (10): 101008. doi:10.1115/1.4039857. ISSN 0022-0434.
·· Genta, G. (1985), "Application of flywheel energy storage systems", Kinetic Energy Storage, Elsevier, pp. 27–46, doi:10.1016/b978-0-408-01396-3.50007-2, ISBN 9780408013963
·· Egorova, Olga; Barbashov, Nikolay (2020-04-20). Proceedings of the 2020 USCToMM Symposium on Mechanical Systems and Robotics. Springer Nature. pp. 117–118. ISBN 978-3-030-43929-3.
·· [1], "Маховик", issued 1964-05-15
·· "Technology | KEST | Kinetic Energy Storage". KEST Energy. Retrieved 2020-07-29.

1. · Genta, G. (2014-04-24). Kinetic Energy Storage: Theory and Practice of Advanced Flywheel Systems. Butterworth-Heinemann. ISBN 978-1-4831-0159-0.

• Weissbach, R. S.; Karady, G.G.; Farmer, R. G. (April 2001). "A combined uninterruptible power supply and dynamic voltage compensator using a flywheel energy storage system". IEEE Transactions on Power Delivery. 16 (2): 265–270. doi:10.1109/61.915493. ISSN 0885-8977.
• "Synchronous Generators I" (PDF).
• https://pserc.wisc.edu/documents/general_information/presentations/presentations_by_pserc_university_members/heydt_synchronous_mach_sep03.pdf

Dual mass flywheel – Its purpose and main failures
Dual mass flywheel production first started in the 1980's. They were originally developed to address the escalation of
torque and power, especially at low revs on new higher horsepower vehicles and to increase comfort for the driver.

A Dual Mass Flywheel essentially consists of two components (the primary & secondary mass) linked together by a damping mechanism consisting of arc springs and spring guides and located by a central bearing/bushing. The damping springs inside the flywheel allows the D.M.F to filter the torsional engine vibrations away from the gearbox and reduces the load on the transmission line. The larger damper in the D.M.F is better suited for filtering the engine vibrations (especially needed for turbo diesel engines).

The dual mass flywheel allows driving at lower engine speeds thus increasing engine efficiency. This in turn saves fuel and
reduces CO2 emissions as well as any vibration that can cause “gear rattling” & “body booms”.
[IMG]file:///C:\Users\User\AppData\Local\Temp\msohtmlclip1\01\c lip_image002.jpg[/IMG]
As with any wearing component, over time the damping springs and mechanism begin to wear and weaken. As the mileage increases, the damping mechanism becomes weaker to the point where the movement between the primary and secondary masses increases to where it
no longer functions to the best of it’s ability and its performance dramatically reduces. When this happens the flywheel will no longer be able to adequately filter out violent variations of torque or revolutions that could cause an unwanted vibration or rattle when driving.
These vibrations can usually be felt on the floor of the car and are due to the failure of the springs and other internal components. This leads directly to the flywheel’s inability to dampen the tremors with use and it must be replaced.

Causes Of Dual Mass Flywheel Failure

There are many reasons why a dual mass flywheel can fail.
The main reasons are:

Heat - Excessive heat is a big cause of most dual mass flywheel failures. A slipping clutch generates heat; if your clutch is worn, you can still save the flywheel if you get the clutch replaced early enough.
Abuse - Engaging the clutch violently can damage the internal mechanisms of the flywheel. There's a happy medium between smoothly engaging the clutch and excessively sliding the clutch when disengaging it, if you find that point, you can avoid premature failure
Type of driving - A flywheel can last much longer if a vehicle is primarily used for motorway driving where gear changes are considerably less than city driving. Like any other part on a car, the driving conditions can make a big difference on when a dual mass flywheel fails.
Mileage - At some point every wearing part is going to fail from natural use. Once a component comes to the end of its natural life cycle it will need to be replaced.

Material selection
Flywheels are made from many different materials; the application determines the choice of material. Small flywheels made of lead are found in children's toys.[citation needed] Cast iron flywheels are used in old steam engines. Flywheels used in car engines are made of cast or nodular iron, steel or aluminum.[10] Flywheels made from high-strength steel or composites have been proposed for use in vehicle energy storage and braking systems.
The efficiency of a flywheel is determined by the maximum amount of energy it can store per unit weight. As the flywheel's rotational speed or angular velocity is increased, the stored energy increases; however, the stresses also increase. If the hoop stress surpass the tensile strength of the material, the flywheel will break apart. Thus, the tensile strength limits the amount of energy that a flywheel can store.
In this context, using lead for a flywheel in a child's toy is not efficient; however, the flywheel velocity never approaches its burst velocity because the limit in this case is the pulling-power of the child. In other applications, such as an automobile, the flywheel operates at a specified angular velocity and is constrained by the space it must fit in, so the goal is to maximize the stored energy per unit volume. The material selection therefore depends on the application.[11]
The table below contains calculated values for materials and comments on their viability for flywheel applications. CFRP stands for carbon-fiber-reinforced polymer, and GFRP stands for glass-fiber reinforced polymer.

Material

Specific tensile strength ( k J k g ) {\displaystyle \left(\mathrm {\frac {kJ}{kg}} \right)}

Comments

Ceramics
200–2000 (compression only)
Brittle and weak in tension, therefore eliminate
Composites: CFRP
200–500
The best performance—a good choice
Composites: GFRP
100–400
Almost as good as CFRP and cheaper
Beryllium
300
The best metal, but expensive, difficult to work with, and toxic to machine
High strength steel
100–200
Cheaper than Mg and Ti alloys
High strength Al alloys
100–200
Cheaper than Mg and Ti alloys
High strength Mg alloys
100–200
About equal performance to steel and Al-alloys
Ti alloys
100–200
About equal performance to steel and Al-alloys
Lead alloys
3
Very low
Cast Iron
8–10
Very low[12]
The table below shows calculated values for mass, radius, and angular velocity for storing 250 J. The carbon-fiber flywheel is by far the most efficient; however, it also has the largest radius. In applications (like in an automobile) where the volume is constrained, a carbon-fiber flywheel might not be the best option.

Material

Energy storage (J)

Mass (kg)

Radius (m)

Angular velocity (rpm)

Efficiency (J/kg)

Energy density (kWh/kg)

Cast Iron
250
0.0166
1.039
1465
15060
0.0084
Aluminum Alloy
250
0.0033
1.528
2406
75760
0.0421
Maraging steel
250
0.0044
1.444
2218
56820
0.0316
Composite: CFRP (40% epoxy)
250
0.001
1.964
3382
250000
0.1389
Composite: GFRP (40% epoxy)
250
0.0038
1.491
2323
65790[13]
0.0365
Table of energy storage traits

Flywheel purpose, type

Geometric shape factor (k)
(unitless – varies with shape)

Mass
(kg)

Diameter
(cm)

Angular velocity
(rpm)

Energy stored
(MJ)

Energy stored
(kWh)

Energy density (kWh/kg)

Small battery

0.5

100

60

20,000

9.8

2.7

0.027

Regenerative braking in trains

0.5

3000

50

8,000

33.0

9.1

0.003

Electric power backup[14]

0.5

600

50

30,000

92.0

26.0

0.043[15][16][17][18]

For comparison, the energy density of petrol (gasoline) is 44.4 MJ/kg or 12.3 kWh/kg.
High-energy materials
For a given flywheel design, the kinetic energy is proportional to the ratio of the hoop stress to the material density and to the mass:

• E k ∝ σ t ρ m {\displaystyle E_{k}\varpropto {\frac {\sigma _{t}}{\rho }}m}

σ t ρ {\displaystyle {\frac {\sigma _{t}}{\rho }}} could be called the specific tensile strength. The flywheel material with the highest specific tensile strength will yield the highest energy storage per unit mass. This is one reason why carbon fiber is a material of interest.
For a given design the stored energy is proportional to the hoop stress and the volume: it is true.



The AA comment quote:


AA technical specialist Vanessa Guyll to explain the issue. She said: “David's Vectra uses a complex dual-mass flywheel. These smooth out the vibrations from modern, powerful diesel engines. They're not as reliable as solid flywheels, but should last at least four to five years.”28 Mar 2012


I am hoping the text I have lifted from my word document has come over to this platform.
Alan

[Mike Noc]

Originally Posted by alanaslan

The engine set up had no compression but did have a clear distributor and the ignition system had a power supply so the spark could be seen on the compression stroke prior to the power stroke.

Sent from my iPad using Tapatalk

I still use an old Colourtune plug to set up the carb on my Norton - fascinating to be able to look into each cylinder and actually see the fuel igniting.

[MSS]

Good morning, Alan.

Thanks for posting the detail, on which I will make a number of observations.

1. The AA person did not say that DMF last 4-5 years as originally stated. She said 'They're not as reliable as solid flywheels, but should last at least four to five years.”28 Mar 2012' as you correctly note above. I read this as a general comment, not based on detailed information, and one which indicates that they are highly reliable. Other than that, the statement is of zero value.

2. I do not see a characterised mathematical model of the physics of a solid flywheel vs a DMF. Therefore, based on what has been posted, it can not be stated that a DMF offers no advantage over a solid flywheel.

3. I agree with you that a flywheel is a mechanical low-pass filter as a first order approximation. But, a DMF, due to the presence of the additional reactive (inductive) components, will be a more effective filter if properly designed.

There is nothing in what you have posted to convey the argument that a DMF does not offer advantage over a solid flywheel.

My apologies if there is more to come and I am jumping the gun.

Here is a very readable paper on DMF from Schaeffler, the parent company of LUK.


https://www.schaeffler.com/remotemedien/media/_shared_media/08_media_library/01_publications/schaeffler_2/symposia_1/downloads_11/4_DMFW_1.pdf


Maninder.

[MSS]

Originally Posted by Mike Noc

I still use an old Colourtune plug to set up the carb on my Norton - fascinating to be able to look into each cylinder and actually see the fuel igniting.

I still have mine, together with the Gunson Xenon timing light and their RPM/dwell meter.

[alanaslan]

Originally Posted by MSS

I still have mine, together with the Gunson Xenon timing light and their RPM/dwell meter.

In a lovely wooden box 4 colour tune plugs the timing light and the RPM/dwell meter. There is also a box with a wheel alignment drive over plate.

[alanaslan]

That is me just lost another chunk of data for the post, Sorry Guys I am unable at the moment to copy or even cut and paste the bit I wanted. I had just spent 2 hours retyping part of the data and it has vanished with out trace. I am going to blame my age.

My apologies to all
Alan