Adventure EV

Tachometer Sender

Motor Installation Complete!

by on Dec.09, 2009, under EV Land Rover, Motor Adapter, Motor Bracket, Tachometer Sender

Last we left the motor mount situation, I had welded new brackets to the frame of the Rover.

While the motor was out, and the bracket paint drying, I took the time to bore a 12mm hole in the side of the clutch bellhousing to house a proximity sensor used to generate a tachometer signal.  The motor controller can use this signal to discover how fast the motor is spinning in order to limit motor rpm for safety and longevity.  A tachometer also comes in handy when datalogging and giving user feedback.  I can use the tachometer to determine which gear to be in to optimize efficiency (there are other tools for this, as well, but motors like to spin faster rather than slower, within limits.)

Proximity Sensor

I also had to remove the flywheel to grind two notches, set 180 degrees apart, into the side.  The proximity sensor detects the presence of metal within 2mm of its face.  When placed 1.5mm from the flywheel edge, it will detect the presence of the flywheel.  When a 2mm deep notch rolls by the sensor doesn’t see metal anymore, breaks the connection, and that creates a pulse.  The circuitry in the motor controller and tachometer count the pulses, divide by two, and output motor revolutions per minute.

Proximity Sensor Installed

I used an AM1-AN-1A proximity sensor from Automation Direct for about $20.  It has three-wires and is shielded with a sensing range of 2mm.  They sell others that sense up to 6mm if necessary.  Of the three wires, one connects to a power source (10-30VDC, in this case 12VDC), the other to ground, and the third outputs the pulse signal.  Some proximity sensors require a pull-up resistor to provide a clean signal, though the tech at Automation Direct assures me that this particular model does not need one.  In order to easily set the distance, (when attached to a power source) the sensor is equipped with a yellow LED that will light up if the sensor is sensing something.  Very handy.

With the flywheel installed again, along with the clutch and clutch pressure plate, I maneuvered the motor into place in front of the transmission input shaft, and after much cursing and back tweaking, the two were  successfully connected.

I know, I know… it seems everyone’s EV blog has some video of the time the motor was first installed and run off a 12V battery to see if everything was working.  Yeah, my Dad and I did that, but it was late and really freakin’ cold, so I’ll save that tidbit for another day.  But the wheels did spin!

The only problem was that a leaking clutch slave cylinder (I should have know if the master was leaking the slave wouldn’t be far behind) meant disengaging the clutch was a no-go.  By the way, this was all done with the rear wheels off the ground… not toodling across the snow covered mesa.  A new clutch slave arrives tomorrow evening.  Hopefully the lack of full clutch control really is just the slave cylinder and an adjustment, rather than a miscalculation, by me, on the motor adapter side.

Now that the motor was fully mounted to the transmission, I could concentrate on attaching the motor to the new motor mount brackets on the chassis.  Glance into the way-back machine and you’ll find a photo of a round bracket assembly in two halves that I posted earlier.  Here it is again:

11" Motor Bracket

11" Motor Bracket

It wasn’t possible to attach the chassis brackets to a position in-line with where the round motor bracket would go.  So I came up with this bit of metal-jiggery:

Motor Bracket Modification

The round motor bracket halves cradle the motor, and 2″ x 3″ square tube was welded to the top half of the round bracket.  The square tube transfers the weight onto the chassis brackets via rubber-filled motor mounts, the same mounts used when the ICE was in place.  I realize that this puts quite a bit of stress on the union between the square tubing and the round brackets.  Again, hopefully the welds will hold up, as well as the metal stock.  Everything looks and feels beefy enough, though.

Motor Bracket Detail
Underside of top motor bracket
Motor Bracket Closeup
Bracket in place on rubber mounts prior to paint

Below is the final result fully painted and bolted together.  It can’t be seen, but there’s a 5/16″ Grade 8 bolt that connects through the upper part of the motor band to the lifting eye socket in the motor.  This should help prevent the motor from rotating under load.  Amazingly, everything aligned properly and the motor sits correctly!  I mean, I meant for it to be like that…

Final Motor Install

With the motor fully in place, I can now concentrate on the fabrication of the front battery box and the bracketry for the electronics that live under the bonnet.  Next time on… Adventure-EV…

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