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Switchboard Design #23

Closed chadjmccolm closed 6 years ago

chadjmccolm commented 6 years ago

Context

A switchboard would be nice to connect to a power supply and have three switches for:

This could be a laser cut box or something to that effect with built-in fuse holders so that all the power distribution can be controlled through it. Care will need to be given to the wiring on the starter so that the current doesn’t burn through the wire. 10GA is recommended but will be determined with the draw on the starter.

It is also possible to combine this function with the potentiometer used for throttle control as both with be exclusively used for bench testing and will serve as a model for the final product that is run at competition.

This is a low priority task because it would be used only for testing however if somebody is interested in running with it that would be awesome.

Additional info can be found in the engine review doc here.

Outcomes

The outcomes for the project are the following:

Constraints

Being a bit of a passion project for anybody who cares about it enough, the constraints are up to the designer.

Related Issues

Related issues include:

chadjmccolm commented 6 years ago

I drew up a schematic including part numbers for what the basic implementation of this would be.

photoscan

I've also attached my Digikey parts list.

Parts List.xlsx

I have yet to find a part for the starter relay because we need to measure the current to the starter first and I don't yet know a way to do that.

chadjmccolm commented 6 years ago

In addition to the previous parts list we will need a way to bring power on to the board and to ground local components. I suggest using something like this: https://www.digikey.ca/product-detail/en/phoenix-contact/1856168/277-10358-ND/5428734

chadjmccolm commented 6 years ago

The Arduino does use a voltage regulator for the VIN port so the regulator will be cut from the design. A 20 PIN Delphi will likely be board mounted to connect power to all system except starting. Starting will continue to be conducted using the Snap-On starter as detailed in the engine review doc linked above and the starting circuit will be removed from the design.

The switches we'd like to use are rated for 10A and can switch everything directly however depending on the board connection and the draw of each component it may be more beneficial to attach them to relays.

Each component's draw is under further investigation.

chadjmccolm commented 6 years ago

I would like to use a 20pin from Molex to connect all the power and ground outputs from the board but I need to know the current per pin first. I've contacted them as on the datasheet it said "Contact Molex" under current rating. I'm very open to using some other kind of connector too being as some items need about 5-10A (fan and fuel pump)

chadjmccolm commented 6 years ago

Grounds for each component will be coupled into one ground to save space. The injector is the exception as it does not have a ground because ground is connected by the MS to fire.

Current components are:

chadjmccolm commented 6 years ago

Finally decided on what connectors I want to use to all the powered electronics. Any outside input on this would be much appreciated. Now I just need to figure out what style I want for the input...

https://www.digikey.ca/product-detail/en/switchcraft-inc/RASPC10/SC1938-ND/3909321 https://www.digikey.ca/product-detail/en/switchcraft-inc/S10K/SC1949-ND/3909314

I still need a better idea of how much power everything will draw. The best way I can see to do this is by measuring the the current draw of everything. High current things may be measured using a shunt such as this one https://www.digikey.ca/product-detail/en/riedon/RSN-150-50B/696-1758-ND/6819378

It may be a good idea for us to invest in one of these.

chadjmccolm commented 6 years ago

Let's use screw down terminal blocks for connecting power and ground so we can have it insulated from the exterior but still allow for any variety of connections

https://www.digikey.ca/product-detail/en/eaton/EM292902-UL/283-4339-ND/3525886

The screws can be accessible from the top of the case with the switches too.

Now all that remains is how the switches will be connected to the board which will also dictate if they're used directly or through a relay

chadjmccolm commented 6 years ago

I'm thinking maybe a terminal block to connect to the switches like https://www.digikey.ca/scripts/DkSearch/dksus.dll?Detail&itemSeq=241213983&uq=636437911100604184 Then we'll be able to connect each switch to the board well and still have them be removable if a switch breaks.

chadjmccolm commented 6 years ago

To connect the signal wires I was thinking of using a D-Sub connector like this one https://www.digikey.ca/product-detail/en/assmann-wsw-components/A-DF-09-A-KG-T2S/AE10921-ND/1241800 in place of our usual molex PCB header system purely because of availability and cost. I don't think the Molex plugs have any benefit beyond being industry compatible.

chadjmccolm commented 6 years ago

I'm killing off the idea of mounting an Arduino like a shield. Instead we're going to mount a chip and integrate one into the board.

chadjmccolm commented 6 years ago

With the addition of the heated O2 sensor using 7 barrel connectors has stopped making sense. The new idea is to use Molex products from the more available MX150L line. We will also use a Molex MX150L plug for the signal wires to the ETB Driver.

For the 14 power/ground connections: https://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=241209481&uq=636437842707444184 and https://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=241209485&uq=636437842707444184

For the 6 lines running only to the ETB Driver: VDD, INA, INB, ENA, INB, PWM we will use a https://www.digikey.com/product-detail/en/molex-llc/0194180020/WM17411-ND/614727 and a https://www.digikey.com/short/q713t2 .

To accommodate both these plugs we need to make sure we have appropriate pinning equipment so we'll need https://www.digikey.com/product-detail/en/molex-llc/0194200002/WM2978CT-ND/2405692 for the female plugs.

chadjmccolm commented 6 years ago

To have the Arduino built into the board I will use the following components:

chadjmccolm commented 6 years ago

To keep everything through hole I'm switching to these fuse holders https://www.digikey.ca/short/q71308

chadjmccolm commented 6 years ago

Here is my final parts list. Dyno Box Parts List.xlsx

Basic design is done. Now I am going to make each component in Altium and get the schematic and PCB designed. 

Total parts cost estimate: $150
PCB estimate: $80

Running project estimate: $260
chadjmccolm commented 6 years ago

I had to add this relay to the parts list https://www.digikey.ca/scripts/DkSearch/dksus.dll?Detail&itemSeq=241583120&uq=636440536498959412 because the fan runs at 30A max and our switches only support 20A.

chadjmccolm commented 6 years ago

Switchboard design has been abandoned for now because the real benefits have been the learnings of designing the board was the largest benefit in the cost/benefit analysis. It may be revisited at a later date.