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Grundfos Challenge: Design and integration of a gear unit for a hydronic valve into an enclosure box

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Pumps and valves are vital components in any hydronic system and their performance can make a huge difference on the overall system performance. An essential part of valves performance is their ability to always position the valve seat correctly. Several contradictive parameters are involved in such positioning systems by which an optimal solution is achieved through best compromise. The Grundfos Challenge is therefore to provide solutions for design and integration of a gear unit for a hydronic control valve.

The Challenge
The Challenge is design and development of a gear unit for a hydronic valve that is thoroughly integrated into an enclosure box. Thus, we seek the best solution to the challenge: How can a gear drive train system, that meets certain gear box requirements, be designed, while ensuring a thorough integration of the system into the enclosure box to accommodate the structural integrity of the product? (See figures and attached CAD drawings). The solution is bounded by the technical requirements to the enclosure box, design-space envelope and gearbox (shaft output torque etc.) specified below

Requirements

  • Technical Requirements (See details in Case Documentation)


    Enclosure box (red in attached figures)
    • The enclosure box is sealed by a lid (not shown). The lid should not be designed nor be considered with respect to the structural integrity
    • Outer surfaces of the enclosure box cannot be changed
    • Inner surfaces of the enclosure box may be changed to form the interface to the gear system e.g. adding towers, pins, etc. to transfer loads to the box
    • All forces from the gear train are transferred via the box
    • All degrees of freedom are fixed at the end of the cylindrical face (blue circle in attached figures)
    • Manufacturing: Injection molding, tool disassembly direction, Z.
    • Min. material thickness: 1mm
    • Material: Polycarbonate 10% glass fiber – Assume linear material properties (23 degrees Celsius): E=4.114GPa, ν=0.38, ρ=1270kg/m3
    • Assembly: Gear unit is mounted in the enclosure in the Z-direction


    Design-space envelope
    • The gear drive train system must fit within the specified design-space envelope of the enclosure box (black/grey box – see figures and attached CAD drawings).
    • The motor must also fit within the design-space envelope.


    Gear system
    • Free choice of gear system e.g. planetary, worm, spur etc.
    • Minimal maintenance systems are preferred
    Electric motor
    • The motor for the gear system is pre-specified and provides a well-defined input torque: See attached motor pull out torque curve (clockwise and counter-clockwise)
    • Allowable RPM range: 500-1500RPM
    • Dimension: See attached CAD file
    • Shaft connection: Flat shaft
    • Operation mode: 3 sec ON followed by 7 sec OFF

    Output shaft
    • RPM: 1 RPM +/- 5%
    • Torque: 20Nm +/- 1Nm (at 1 RPM)
    • Radial rotating force: Maximum 300N at tip
    • Movement: Bi-directional (open/close of valve) – 360 degrees in both directions (no fixed stop)
    • Hysteresis: < 3 degrees
    • Material: Steel – E=200GPa, ν=0.3, ρ=7800kg/m3
    • Shaft Connection: Oldham

  • Judging criteria

    1. Are the technical requirements met?
    • Within the design-space envelope?
    • Is assembly in Z-direction possible?
    • Etc.

    2. Is the solution considered reliable and robust?

    3. Is the gear principle novel and maintenance-free?

    4. Designs with the following features are favored:
    • Non-lubricated gear systems
    • The compactness of solution (considering potential thermal risks for gear unit and PCBs in enclosure box)
    • Low weight
    • Low cost
    • Low hysteresis on the output shaft

    5. Alternative and creative features to improve the product and/or its application further e.g. out-of-spec. application, added value, improved robustness, manufacturing, high lifetime, maintenance-free, etc.

  • Submission

    • Submit CAD files in STEP format
    • Screenshots in various views (preferably rendered)
    • Screenshots of simulation results (if applicable) and a small description of the setup (so that it can be replicated by the jury)
    • Documentation incl.
    - Gear ratio
    - Bill of material incl. material composition
    - Design considerations e.g. on manufacturing, assembly, reliability etc.
    - Description of alternative/creative features
    - Etc.

  • *DOWNLOAD IMPORTANT FILES BELOW*

    Be sure to use the Specification Download button below to Download the Case Documentation, Pictures and CAD Files for this Challenge (The CAD Files are Required for this Challenge!)

Download specification

Rules

  • ENTERING THE COMPETITION:


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      GRUNDFOS CHALLENGE SPECIFIC ENTRY AGREEMENT:
      By submitting an Entry in the Grundfos Challenge, each Top 3 Finalists grants to Grundfos (Sponsor) and its designees a worldwide, non-exclusive, sub-licensable, transferable, fully paid up, royalty-free, perpetual, irrevocable right to use, reproduce, distribute, create derivative works from, publically perform, publically display, digitally perform, make, have made, sell, offer for Sale and import the Entry and to develop or have developed the technology described in the Entry, in any media now known or hereafter developed for any purpose whatsoever, commercial or otherwise, without further approval by Entrant (“Non-Exclusive License”).

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      By submitting an Entry, Entrant represents that is has the right to grant these rights and the Exclusive License.

  • SUBMITTING AN ENTRY


    Only entries uploaded to GrabCAD through the "Submit entry" button on this Challenge page will be considered an entry. Only public entries are eligible. We encourage teams to use GrabCAD Workbench for developing their entries. Entries are automatically given the tag "GrundfosChallenge2019" when uploading to GrabCAD. Please do not edit or delete this tag. Only entries with valid tag will participate in the Challenge.

  • AWARDING THE WINNERS


    The sum of the Awards is the total gross amount of the reward. The awarded participant is solely liable for the payment of all taxes, duties and other similar measures if imposed on the reward pursuant to the legislation of the country of his/her residence, domicile, citizenship, workplace, or any other criterion of similar nature. Only 1 award per person. Prizes may not be transferred or exchanged. All winners will be contacted by the GrabCAD staff to get their contact information and any other information needed to get the prize to them. Payment of cash awards is made through PayPal. All team awards will be transferred to the member who entered the Challenge.

  • We will release the finalists before the announcement of the winners to give the Community an opportunity to share their favorites in the comments, discuss concerns, and allow time for any testing or analysis by the Jury. The Jury will take the feedback into consideration when picking the winners.


    Winning designs will be chosen based on the Rules and Requirements.

  • Schedule


    This Challenge ends on November 19th, 2019 (23:59 EST.) Finalists will be announced on November 26th, 2019. Winners will be announced on December 3rd, 2019.

Prizes

Prizes

$10000 in Prizes

1st Place

$6000

2nd Place

$3000

3rd Place

$1000

*IMPORTANT*
All prizes will be awarded through Paypal. Please make sure that you have a Paypal account ready beforehand when we start awarding prizes to get your winnings quicker. We will NOT use any other payment method to award your winnings.

About Grundfos

Grundfos is a global leader within advanced pump solutions employing more than 19,000 employees in 56 countries worldwide. Our purpose is to pioneer solutions to the world’s water and climate challenges and improve quality of life for people.
We dare to do things that others do not in order to overcome the complex challenge of moving water in the most intelligent and energy efficient way. We believe that innovation is not only a business opportunity, but an obligation. And what really matters to us is not short-term profit, but the impact we make. We have the determination and power to set the standard for the industry and society as a whole. We are not only pioneers. We are also game changers.

For more information, visit our company website at www.grundfos.com.

91 comments

  • SWARAJ BISWAS

    SWARAJ BISWAS 23 days ago

    Please specify the following: 1. What will be the operating speed of the motor. 2. If there is no operating speed, then please specify the top speed of the motor.

    SWARAJ BISWAS has uploaded 30 CAD models & has left 28 comments.
  • Chris Tziros

    Chris Tziros 23 days ago

    Under the section called "Gear Unit" you have specified the material properties by writting "Material: Steel – E=200GPa, ν=0.3, ρ=7800kg/m3".
    Is this a restriction only for out gear unit casing?
    Our we allowed to use deferent materials on the gears themselves?
    Also what is happening on the side of the red-Enclosure box that is not beeing shown? Should we design it, Is it going to be open to the enviroment (air/water), is it going to be sealed, or should we just leave that out of our design considerations?

    Chris Tziros has uploaded 17 CAD models & has left 45 comments.
  • neomechanikos

    neomechanikos 23 days ago

    Questions:
    1. What is the total rotational distance required to actuate the valve?
    2. Is it correct to assume the Z direction is indicated by the blue arrow?
    3. Please explain "no fixed gear principle" in the gear system requirements. Should this be interpreted that there are no specific gear requirements?
    4. What is the method of transferring the motor torque to the gearbox and to the valve? Such as keyed shaft, shaft flat, spline, force fit, etc.
    Thank you.

    neomechanikos has uploaded 0 CAD models & has left 2 comments.
  • Lasse Ledet

    Lasse Ledet 23 days ago

    Hi all,

    Thanks for your questions. We will update the requirements with your inputs ASAP, but for consistency here are the answers to your inquiries:

    SWARAJ BISWAS: There is no fixed RPM requirements for the motor, however, the allowable RPM range is specified to 500-1500RPM

    Chris Tziros: It is only the output shaft where steel is required. For the remaining gear system, it is entirely up to you – even for the gear unit casing. Regarding the enclosure box: It is sealed by a lid (not shown), which need not be designed nor a part of the design considerations. Similarly, the structural integrity should be preserved also without considering the lid

    neomechanikos: 1) The total rotational distance is 360 degrees in both directions with no fixed stop (because the enclosure box may be oriented in several ways with respect to the valve seat. 2) Yes, this is correct, thanks for pointing it out. 3) There are no requirements to which gear technology you decide to use e.g. it may be planetary, worm, spur gears etc. 4) The connection between the motor and gearbox is with a flat shaft connection and between the output shaft and valve an Oldham connection (however this connection may be neglected).

    I hope this answers your inquiries, otherwise feel free to comment again

    /Lasse

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Kesa

    Kesa 22 days ago

    There is an Update in the Specifications download. Please download the new Version if you havent already.

    Kesa has uploaded 1 CAD models & has left 72 comments.
  • Lukasz

    Lukasz 22 days ago

    After downloading the specification, there are no CAD files

    Lukasz has uploaded 1 CAD models & has left 1 comments.
  • Ben Casto

    Ben Casto 22 days ago

    Are the final output figures quoted as if the motor was running constantly or do these include the 7 second off time?

    Ben Casto has uploaded 13 CAD models & has left 53 comments.
  • Kesa

    Kesa 22 days ago

    The new Specification Should have the files in there now. Thank you Lukasz

    Kesa has uploaded 1 CAD models & has left 72 comments.
  • Thomas Sutrina

    Thomas Sutrina 21 days ago

    The gear ratio is large. The likelihood that any type of gear train can be back driven is small. The torque electrical connection is not presented and the torque curve is typical of a PM motor or a stepper motor. Your graph does not present the toque at zero RPM Which suggest that the motor is not design to operate to hold position. So is a requirement that the gear train can not be back driven?

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Thomas Sutrina

    Thomas Sutrina 21 days ago

    Please elaborate, "Torque: Maximum 16Nm at 1 RPM and Radial rotating force: Maximum 300N at tip." Is the maximum torque created by the maximum force as some lever length? Does the housing of the gearbox we are responsible for required to take the 300 N maximum force? and if so what is the lever length along the Z axis. Otherwise I would assume that your enclosure or the valve body handles the forces generated by the fluid and the closure contact forces except for a pure torque, 16 Nm. What is the torque at closure; zero RPM? Obviously this is the actual final condition the motor must drive the valve up to. Also what is the hysteresis to initiate motion, zero to 1 RPM?

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Thomas Sutrina

    Thomas Sutrina 21 days ago

    No position senors are required, however; some means of determining the closure of the valve is needed. This could be mechanical stops in the valve and once the torque exceeds a value which has a matching current your controller turns it off. Two position valve. For a position-able valve you may have sensors elsewhere. Other approaches such as time and angle or turns count of the motor would do the same thing from the two stops. I do not know the details but the choice of drives would be effected.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 20 days ago

    There is a typo somewhere in the description... the output torque says 20Nm in the pdf file I downloaded. However it says 16Nm in the above description. Which is it? 4Nm is a significant amount of torque.

    Also, it is impossible to meet the power requirements as listed. To move the output shaft 360 degrees in 3 seconds, you would require 16Nm x 2pi radians / 3 seconds. This is 335 watts.

    The motor provided can only deliver 1/10th this amount. For example, at 800 RPM, the curve shows 40mNm, giving a maximum power of 3.35 watts. I'm hoping that the valve actuator (output) shaft has 10 times the amount of torque listed, or that the time requirement is 30 seconds instead of 3.

    Can someone please clarify this? It impacts my design.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 20 days ago

    I'm sorry, the output would be 33.5 watts in the above comment ^^^, I guess we are all liable to have typos :)

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Nic

    Nic 20 days ago

    In regards to the motor, should the electrical connector be flush with the external envelope to allow for direct connection, or, should the cabling be passed via a grommet of some type? Is the motor hard-wired with no pluggable connection?

    Nic has uploaded 25 CAD models & has left 84 comments.
  • Chris Tziros

    Chris Tziros 19 days ago

    So, what is the output torque at 1 rpm, 16 or 20 Nm?

    Chris Tziros has uploaded 17 CAD models & has left 45 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 19 days ago

    Chris Tziros, I'm going to roll with 1.6Nm until I am told otherwise for the power reasons stated above. That's a 10 times difference in output torque, but it's either that or they let us take longer to do the move.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • geo

    geo 19 days ago

    @ Grundfos: To have a better final solution, a feedback for All is helpful. Evaluation example: Function = 2 points, manufacturability = 9 points, number of parts / costs = 10 points. Result = 7.0 points. A gear ratio 1:85 is mandatory.
    I am of the opinion, that Courtesy in the wrong place does not produce a good construction.

    geo has uploaded 17 CAD models & has left 663 comments.
  • Sava Savov

    Sava Savov 19 days ago

    Brandon, I think you don't have to "... move the output shaft 360 degrees in 3 seconds...". The output speed must be 1 rpm, as far as I can see. So if output torque is 16 Nm you get for the output power: P=16Nm x 2pi radians / 60 seconds = 1,676 W. I think that the problem will be the input power because it depends on mechanism - how much will be the mechanism resistance (how much power will be needed to overcome this resistance before we can get the final output power).

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 19 days ago

    Sava, I am totally good with that understanding. I guess the "on time 3 seconds, off time 7 seconds" can be thrown in the trash can and we stick with the 1 RPM as a fixed output speed and the 1.676 W is the power output required, which is theoretically possible to accomplish with the approximately 3.35 W max output on the dinky little motor. Thanks for the comment!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 19 days ago

    And yes, the mechanism efficiency would have to be no worse than 50%. This is the challenge. Let's see what we can do!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Thomas Sutrina

    Thomas Sutrina 19 days ago

    This is a small valve so my guess is that the traveling torque could be 1/10 or less of the value to setting or breaking the sealing of the valve. However that also requires the zero RPM torque point of the motor. Generally the pressure drop across the valve times the area of the closure and time the drag coefficient for rotation is small until almost full closure is approached. The only exception is for a butterfly valve that is only used for large valves.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 19 days ago

    I was curious about the type of valve as well.... I have a few ideas about mechanisms that would not give constant torque through the full move, but they would maintain on average >16Nm. It's kind of a moot point though since they don't specify the resistant torque profile through the move.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Sava Savov

    Sava Savov 19 days ago

    Maximum torque is 16 Nm (or 20 Nm) but is there a minimum torque that can be acceptable for valve to work properly?

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 18 days ago

    If the requirement was constant torque, constant speed, then the list of available approaches to the design is somewhat limited. If we are allowed some wiggle room, for example a sinusoidal, cycloidal, or other type of curve on the angular velocity of the output shaft, then we have a few other options on the table. Since it is a valve and as Thomas pointed out there are places where you won't see a whole lot of resistance, some of these approaches can be "clocked" so that the high points on the output torque curve would align with the points of high resistance. And who really cares what the angular velocity profile of a closing valve at 1 rpm really is? It's slow as all hell.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Lasse Ledet

    Lasse Ledet 18 days ago

    Hi all,

    Thanks for all the great comments. We are very glad to see passionate people that are keen to solve a problem that is not so easy. I’ll try to answer your questions below.

    First, sorry for the confusion about the torque level. The correct specifications are: 20Nm +/- 1Nm (as in the attachments). We will correct this ASAP.

    Besides the torque, the output shaft must also withstand the radial force (simultaneously). It is placed at the tip of the shaft (length available from the CAD files) and the force does not produce any additional torque.

    The torque is generated by the resistance of the valve seat and the valve seat itself will ensure that the system is self-contained from hydraulic forces.

    The valve position is feedback controlled by sensors placed in the fluid and its strict position is therefore not important. However, too much hysteresis disrupts stable feedback control.

    The attached motor curve is a test curve for the motor as standalone and not a measurement from operation of the actual system. Extrapolating the motor curve will give you the torque a zero RPM.

    The start torque on the output shaft is included in the torque specifications. The controller handles changing torque e.g. from stationary to moving valve seat.

    The output shaft moves at 1RPM (+/-5%) with an operation cycle of 3 sec. ON followed by 7 sec. OFF. This means that the valve is not able to close in one go. The operation cycle relates to the gear unit’s durability, if designers wish to consider this.

    The motor is a step motor connected by four wires. The wires are connected to a PCB inside the enclosure.

    @geo we agree that a weighting system would generally be convenient, however, as these alternative/creative features are indeed secondary requirements we feel a weighting system is not suitable.

    I hope this answers all your questions otherwise feel free to comment again.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 18 days ago

    Thanks. It clarifies a few things. I think some people are interested in the work required to close the valve into its seat. Let's define 0 degrees as the fully closed state and 360 degrees as the fully opened state. It could be that as we are closing the valve, most of the travel should be of relatively low resistance until some specified angle, that at which the valve seat is interacting with the valve.

    Maybe it's that the valve seat is resisting the 20Nm +/- 1Nm for the entire stroke. That's a lot of work for this little motor to do. But maybe it's only resisting at say that last 45 degrees before valve closed. There is a large difference in the work required here. 8 times more, in fact.

    This is important to know because then the mechanism can be designed to concentrate it's efforts into that last bit of travel. For example you could have the system move quickly through most of the stroke and then spend a lot more time on the portion of high resistance. Otherwise you're just wasting time. Does this make sense?

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • manish shah

    manish shah 18 days ago

    Can anyone explain what the fixed gear principle is ?

    manish shah has uploaded 26 CAD models & has left 59 comments.
  • Lasse Ledet

    Lasse Ledet 18 days ago

    @Brandon: It certainly makes sense and you are absolutely right that the torque on the valve is generally not constant throughout its stroke. However, as the valve may be in the same position for long enough that it can get stuck, we need the 20Nm to make sure we can loosen it again. And unfortunately, this can happen at arbitrary positions.

    @Manish what is meant by “No fixed gear principle” simply means that you may choose whichever gear mechanism you find suitable e.g. spur, worm, mesh etc.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 18 days ago

    Ok, that's reasonable for now. Thanks!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Thomas Sutrina

    Thomas Sutrina 18 days ago

    The step model of the stepper motor does not have a 'D' shape but is round. Your words tell us it is a shaft with a flat. I assume the the step files in the two folders are identical.

    Manish Shah. Fixed gears on a car with a manual transmission means that first gear is a fix ratio. Second is a fix ratio etc. The ratio for a two pulley belt drive is fixed so long as slippage is very small. And induction motor is considered a fixed speed motor because at the design torque the speed is fixed, what is listed for the motor as you know the speed when sold are listed with a few steps.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Thomas Sutrina

    Thomas Sutrina 18 days ago

    It appears that the motor is an TSM49-075 from Anaheim Automation which doesn't have a flat on their base line unit.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Thomas Sutrina

    Thomas Sutrina 18 days ago

    I think we can assume the flat is 1 mm off from the center of the shaft which seems like a standard.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Sava Savov

    Sava Savov 18 days ago

    Is there a problem if the torque is 2-3 times larger than 20 Nm just in beginning of the motion, just to peel off, and then to decrease to 20 Nm until the angular velocity reaches 1rpm? Or it is dangerous the torque to be so high so as to not overload something?

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Sava Savov

    Sava Savov 18 days ago

    After all, why not show the whole valve - no one will steal it, but even if it does, everything is documented here.

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • André Succissi Rinaldi

    André Succissi Rinaldi 18 days ago

    A question that came to my mind on the engine torque chart.
    In the torque axis there is the dimensional mNm, would this dimensional correspond to Nmm or only Nm?

    André Succissi Rinaldi has uploaded 1 CAD models & has left 4 comments.
  • Ananth Narayan

    Ananth Narayan 18 days ago

    @André Succissi Rinaldi, it's mill Newton-meter.

    Ananth Narayan has uploaded 62 CAD models & has left 254 comments.
  • Lasse Ledet

    Lasse Ledet 18 days ago

    @Thomas: Yes, the shaft is just round in the CAD file and you may consider it round or with a D-shape in your design. It will not affect the judgement of your entry :-)

    @Sava: As we are using a step motor you may consider the 20Nm as a maximum since the torque of the motor is proportional to the ampere input. This means that the controller can decrease the torque if needed whereas an increase (above 20Nm) will be damaging for the structure. To not constrain the design of the gear system unnecessarily we have chosen to not disclose the valve.

    @André: It is correct that mNm refers to milli-Newton meter

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Melville

    Melville 17 days ago

    Hi
    I can now grasp the gravity of problem !!
    Gone through the initial stages of gear selection !!
    With the commercial "rigid" drives out there can be a big issue
    I presume that the output required is precise that is 1 rpm with "small" change
    I understand that a range of inputs are given such as 500-1500 RPM
    If we use a gear the ratio is very rigid and the output will be dangerously low
    I think that the solution would be near pure electronic with German VFD

    Melville has uploaded 15 CAD models & has left 8 comments.
  • Sava Savov

    Sava Savov 17 days ago

    A planetary gearbox can solve the problem easy ! But I tried something else and it seems it will work - never saw this before and i will bet on it.

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Thomas Sutrina

    Thomas Sutrina 17 days ago

    "D" flat on the motor output shaft does effect the design. Without a flat then creep on the mate is low enough that friction works via shrink fit or a screw.

    I do agree that for evaluation it doesn't matter since your engineers will fix the problem.

    Thomas Sutrina has uploaded 3 CAD models & has left 31 comments.
  • Chris Tziros

    Chris Tziros 16 days ago

    @Sava Savov,
    what would be the angular backlash of the planetery gearbox though?

    Chris Tziros has uploaded 17 CAD models & has left 45 comments.
  • Sava Savov

    Sava Savov 16 days ago

    I can't translate to myself what exactly backlash means. Maybe if only planetary gearbox is used, the motor must have a brake integrated.

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Halbmond

    Halbmond 16 days ago

    Read all the comments. So the ratio is 500:1 ? Input speed may change 500 to 1500 rpm and output speed 1 to 3 rpm ?

    Halbmond has uploaded 0 CAD models & has left 15 comments.
  • Sava Savov

    Sava Savov 16 days ago

    @Halbmond,
    The nominal output speed is 1 rpm. If you choose the nominal speed of the motor to be 1000 rpm (for example), you have to make a gear box with ratio=1000/1. I thing so.

    Sava Savov has uploaded 19 CAD models & has left 71 comments.
  • Daniel Gelep

    Daniel Gelep 15 days ago

    Damn, I see a lot of comments and I really do not understand what is unclear for you guys ? Input data, output data and requirements are extremely clear. I understand all from one reading without any other question. Is not missing any other info or shall not be need any extra clarification.

    I also start to work on this and I will present at the proper time.

    Good luck to all of you.

    Daniel Gelep has uploaded 0 CAD models & has left 4 comments.
  • Melville

    Melville 14 days ago

    Hi for gearbox planetary number of teeth use "http://www.mekacademy.com/
    for teeth selection !

    Melville has uploaded 15 CAD models & has left 8 comments.
  • Nic

    Nic 14 days ago

    Can we please be given some indication of the intended/prospective production volume for this unit? It would help to inform the choice between off-the-shelf and custom components. Thanks

    Nic has uploaded 25 CAD models & has left 84 comments.
  • Ankush Sharma

    Ankush Sharma 14 days ago

    i am unable to understand 1 thing. we need 1rpm at the output shaft as well as 20Nm torque as well, how can we reduce both torque and rpm at the same time?

    Ankush Sharma has uploaded 0 CAD models & has left 1 comments.
  • Ananth Narayan

    Ananth Narayan 14 days ago

    @Ankush Sharma, please see the documentation pull out graph it's milli-newton-meter. Hope you might have misunderstood. Reduce the speed by increasing torque.

    Ananth Narayan has uploaded 62 CAD models & has left 254 comments.
  • df

    df 13 days ago

    This job to done properly require quite a lot of work. Most probably few months for first the successful iteration, then later do it 2 more times to get it really right. And also quite a lot of testing to get materials right, to get tolerances right and to satisfy all this criteria (which cost quite a lot). I did design for similar project so remember problems. Also, to get `some indication about position` you need to design PCB with electrical schematics, including motor controls and do some software to see if idea works. Good luck with 10 000 usd budget :)

    df has uploaded 1 CAD models & has left 3 comments.
  • Lasse Ledet

    Lasse Ledet 12 days ago

    @Nic you may assume high volume production

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Elie VILLAIN

    Elie VILLAIN 11 days ago

    Hello,
    I have a question about "min material thickness: 1mm"
    Does this also affect the width of the teeth of the gear ?

    Elie VILLAIN has uploaded 2 CAD models & has left 30 comments.
  • Lasse Ledet

    Lasse Ledet 11 days ago

    @Elle, no for the gears you are free to chose as long as they can be manufactured (preferably at a reasonable price). The material thickness is related to the changes you may do on the enclosure box as thicknesses below 1mm give rise to challenges for the injection molding process

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Elie VILLAIN

    Elie VILLAIN 9 days ago

    Thank you Lasse,
    I have an other question : Could it be possible to know roughly the frequency of use of the system ? (hour per day)

    Elie VILLAIN has uploaded 2 CAD models & has left 30 comments.
  • Pammeg

    Pammeg 9 days ago

    Hello,
    for me two things are not clear :
    1.If a constant speed (1 RPM) of output shaft is required (with variable speed 500-1500 RPM of the input motor), or a fixed speed ratio is allowed.
    2. If more than 360 degrees of output shaft rotation are allowed, on only one turn per direction is required.

    Pammeg has uploaded 6 CAD models & has left 10 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 9 days ago

    Hi!
    Is the efficiency of the gearing a consideration? Assuming two solutions achieve 20Nm at 1rpm,would a higher efficiency transfer be preferred?

    Fredrik Lie Larsen has uploaded 14 CAD models & has left 61 comments.
  • Lasse Ledet

    Lasse Ledet 8 days ago

    @Elie: You may expect the operation sequence (3 sec. ON, 7 sec. OFF) to run 24 hours a day, 9 month a year.

    @Pammeg: 1) You should choose a fixed rpm of the motor and then pick the corresponding gear ratio to get 1 rpm on the output shaft. 2) Only 360 degrees in each direction is required, however, it is no problem if the solution can turn even more as long as it can do at least 360 degrees in both directions.

    @Frederik: In fact, the cost of the solution is more important than efficiency. You may consult the judging criteria above to see what is taken into consideration.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • geo

    geo 8 days ago

    My English is too bad to understand the requirements for the competition. With some submissions you can calculate the curvature of space and time by Albert Einstein. I wish all applicants good luck.

    geo has uploaded 17 CAD models & has left 663 comments.
  • Hans Kristian Bruun

    Hans Kristian Bruun 8 days ago

    The 20Nm is primarily to loosen the valve if it gets stuck. Are there any feedback forces from the valve? And do you prefer self-locking gear?
    What is the preferred IP-rating of the enclosure box?

    Hans Kristian Bruun has uploaded 3 CAD models & has left 8 comments.
  • Viktor Bazarov

    Viktor Bazarov 8 days ago

    Why did you change requirement from "no fixed gear systems" to "free of choice" in a mid of challenge ?

    Viktor Bazarov has uploaded 3 CAD models & has left 7 comments.
  • Lasse Ledet

    Lasse Ledet 8 days ago

    @Hans: Assume that there are no feedback forces. The valve itself is self-locking, so it is not a requirement for the gear system. The enclosure box (red) itself incl. its lid (not shown) seals off the gear system from the environment and therefore there are no requirements for the IP-rating of the gear system as it is inside the enclosure box.

    @Viktor: Unfortunately, the wording “no fixed gear systems” has caused confusion and therefore a clarification was needed. The meaning is the same as the original one, which was somewhat clarified in the comments above. The idea is that you are not required to use any special gear system i.e. you are free to choose e.g. planetary gears, worm, mesh, spur etc. And of course, you may choose fixed as well as variable gear ratio systems.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Sanyog Lamsal

    Sanyog Lamsal 7 days ago

    Hello.
    Will the gear system be made in-house or are they imported? If there are any manufacturing constraints for the gear system, please mention it. Or, is it supposed to contain only standard components?

    Sanyog Lamsal has uploaded 13 CAD models & has left 11 comments.
  • Sanyog Lamsal

    Sanyog Lamsal 7 days ago

    Are hysteresis and backlash synonymous ?

    Sanyog Lamsal has uploaded 13 CAD models & has left 11 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 6 days ago

    @Lasse Ledet Where on the output shaft is the oldham connection intended to be mounted? Between the output and the valve, or between the output shaft and the rest of the gear system, on the inside of the enclosure? :)

    Fredrik Lie Larsen has uploaded 14 CAD models & has left 61 comments.
  • Chris Tziros

    Chris Tziros 5 days ago

    1) What is the method via which our last gear will be connected to the output shaft (e.g. keyway, press-fit, set screw, hex-drive)?
    2) Is the connection between our last gear and the output shaft going to be made during the gear unit assembly or during valve instalation on site?

    Both of these questions aim in the proper bearing arrangement selection
    Basically i am trying to understand whether the bearing can be placed on the output shaft after the output shaft has already been connected with our last gear, and whether the bearing can ride on the ouput shaft itself (bearing ID=20mm).

    Chris Tziros has uploaded 17 CAD models & has left 45 comments.
  • Lasse Ledet

    Lasse Ledet 4 days ago

    @ Sanyog: It is entirely up to you whether you want your design to consist of standard components or be manufactured in-house. As mentioned above you may assume a large volume. You may think of hysteresis as the accumulated backlash throughout the entire gear system i.e. when the direction is changed, how many revolutions will it take before the output shaft starts to move. This is typically represented as the corresponding angle on the output shaft i.e. < 3 degrees.

    @Frederik: The Oldham coupling is between the output shaft and the valve. You do, however, not need to account for it in your submission.

    @Chris: 1) You may decide which connection you prefer. 2) Nothing will be assembled on-site, everything should be assembled prior to installation. Thus, you are free to choose the order you would like to assemble the unit in.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Juan Arroyave

    Juan Arroyave 4 days ago

    If you want 300N at the tip, it means that the final power is 15000NM because the tip of the shaft measures 2cm, then T1 (300N) / 2cm = T2 / 100cmm. therefore T2 = 300N x 100cm / 2cm which gives T2 = 15000 NM

    Juan Arroyave has uploaded 394 CAD models & has left 381 comments.
  • Lasse Ledet

    Lasse Ledet 4 days ago

    @Juan: The force acting on the tip has mostly something to do with forces created by e.g. misalignment and this force does not produce any torque as it is a radial force that may be at any arbitrary angle. So, this force must be taken by either the gear system or by a bearing placed in the enclosure box. The choice is yours.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 4 days ago

    @Lasse Ledet Can we change the diameter of the output shaft ( green )? It seems needlessly thick for just 20Nm :)

    Fredrik Lie Larsen has uploaded 14 CAD models & has left 61 comments.
  • Lasse Ledet

    Lasse Ledet 3 days ago

    @Frederik: Sure, it is rather thick for the 20Nm but there are other reasons for having this thickness. However, you may change the diameter of the part of the shaft that is inside the enclosure box.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 days ago

    Nice challenge. What level of detail are the judges looking for? For example, should all fasteners be modeled?

    Vaughan Thomson has uploaded 0 CAD models & has left 4 comments.
  • Juan Arroyave

    Juan Arroyave 2 days ago

    @Lasse Ledet, Is possible you give us the electric motor power??? or torque??? Thanks for your collaboration

    Juan Arroyave has uploaded 394 CAD models & has left 381 comments.
  • Nic

    Nic 2 days ago

    In regards to the 30% duty cycle of the motor (3s on, 7s off) and the determination that the output should operate at 1rpm, is that to say the instantaneous shaft speed should be 1rpm, or should the shaft complete a full revolution in 1 minute, i.e. the instantaneous speed should be 3.3rpm?

    Nic has uploaded 25 CAD models & has left 84 comments.
  • Nic

    Nic 2 days ago

    It seems an impossible task if the required speed is 3.3rpm given the 20Nm requirement?

    Nic has uploaded 25 CAD models & has left 84 comments.
  • Vaughan Thomson

    Vaughan Thomson 1 day ago

    Another question regarding the wall thickness of the red enclosure. I understand that the outer shape must remain the same and additions internally for gear support is allowed. Are are we allowed to reduce the wall thickness in any areas by removing material from the inside of the red enclosure? Whilst keeping with the minimum thickness of 1mm?

    Vaughan Thomson has uploaded 0 CAD models & has left 4 comments.
  • Lasse Ledet

    Lasse Ledet 1 day ago

    @Vaughan: 1) The level of detail is up to you. But of course, the judges are able to see past a few missing fasteners. 2) The enclosure box has its own requirements and therefore the thickness specified. However, there is no problem in removing material locally inside the enclosure as long as you cope with the 1mm requirements.

    @Juan: In the attached material you’ll find a torque vs. RPM graph for the motor from which to can deduce the torque.

    @Nic: The duty cycle should not be accounted for in this regard i.e. the instantaneous speed is the 1rpm.

    Lasse Ledet has uploaded 0 CAD models & has left 12 comments.
  • Vaughan Thomson

    Vaughan Thomson 1 day ago

    @Lasse: Thanks for the feedback.

    Vaughan Thomson has uploaded 0 CAD models & has left 4 comments.
  • Vaughan Thomson

    Vaughan Thomson about 9 hours ago

    I am wandering now about the sealing of the enclosure at the 20mm shaft. In previous comments it has been made clear that the 20mm shaft can be stepped down on the inside of the box. would it be acceptable to step the 20mm shaft down before it enters the box and reduce the hole size to suit? Also will there need to be a provision for a running seal or alternatively would an exposed bearing be allowed here?

    Vaughan Thomson has uploaded 0 CAD models & has left 4 comments.
  • e.g.oussama

    e.g.oussama about 7 hours ago

    you accept STL file

    e.g.oussama has uploaded 26 CAD models & has left 285 comments.
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