Using the standard transmission at stall at 0 rpm, the overall ratio in 1st
gear is 19:1+ and my motor amp meter will peg to 600 amp or more.
Using the automatic with a 12 inch torque converter with a stall speed of
1700 rpm, the motor increases from 0 to 375 rpm which only runs the
transmission pump which increases the transmission oil pressure from 0 to
about 50 psi which the vehicle will start to move. The motor ampere is now
between 150 to 175 amps.
The higher starting rpm at 375 rpm takes less motor ampere than at 0-1 rpm
using a manual or using a direct pump drive that I tried in the automatic
without a torque converter.
The direct drive automatic transmission pump drive also raise the motor
ampere at or above 600 amps which at times made the car jump and spin the
tires. Replace the pump drive with a torque converter that now has a
smoother take off. In name this is what a torque converter does, this one
multiple the torques by 1.8:1 at 0-1 rpm and decreases until it gets to the
stall rpm of 1700 rpm.
In this case, the motor rpm is up high enough at 375 rpm to start moving at
a lower motor ampere over a motor that has to start moving the EV at 0-1
rpm.
In my other car which uses the same type of transmission, the idle speed is
set at 600 rpm and my start moving rpm is closer to 1000 rpm, because I am
running a 2.78:1 differential with a 7.645:1 overall ration.
If it was possible to start moving the standard vehicle at 1 rpm, it will
take more energy and will kill the engine, then it does start moving at 1000
rpm.
Roland
----- Original Message -----
From: "Cor van de Water" <
[email protected]>
To: "Electric Vehicle Discussion List" <
[email protected]>
Sent: Sunday, October 10, 2010 12:40 PM
Subject: Re: [EVDL] torque formulae
> Roland,
>
> How can the current drop from 600 to 150A
> with almost the same gear ratio (19.9 versus 19.5)
> and almost the same vehicle weight (6840 versus 7030 lbs)
> at the same slope?
> I would expect with equal vehicle weight and ratio the
> current should be equal, or am I missing something?
>
> Regards,
>
> Cor van de Water
> Director HW & Systems Architecture Group
> Proxim Wireless Corporation http://www.proxim.com
> Email:
[email protected] Private: http://www.cvandewater.com
> Skype: cor_van_de_water IM:
[email protected]
> Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
> Tel: +91 (040)23117400 x203 XoIP: +31877841130
>
> -----Original Message-----
> From:
[email protected] [mailto:
[email protected]] On
> Behalf Of Roland Wiench
> Sent: Monday, October 11, 2010 12:21 AM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] torque formulae
>
> Here is a motor and acceleration calculator by the 4QD Company at:
>
> http://www.4qd.co.uk/***/current.html
>
> This info is from the Uve's Electric Vehicle Calculator site when it was
> up.
>
> For my EV with a GE-11 motor with a manual transmission at a overall
> gear ratio of 19.495:1, the current is over 600 + amps with a 7030 lb
> vehicle on a 7% slope at motor stall.
>
> Changing the transmission to a GM TH-400 automatic which is modified for
> manual shift only using a large 12 inch torque converter that has a
> variable ratio from 1.8 to 1.0 at 1700 rpm which is the stall speed of
> the transmission. The overall ratio is now at 1.8 x 2.75 x 5.57 =
> 27.5715:1 for a 6840 lb EV at 0 rpm.
>
> The motor will start moving the EV at 375 rpm on the 7% degree slope at
> a 150 motor ampere at a estimate overall ratio 1.3 x 2.75 x 5.57 =
> 19.912:1.
>
> In a normal vehicle with a automatic, the differential gear ratios are
> below 3:1, so the vehicle will only start to move 100 to 200 rpm above
> the idle rpm.
>
> Roland
>
>
> ----- Original Message -----
> From: "Peri Hartman" <
[email protected]>
> To: "'Electric Vehicle Discussion List'" <
[email protected]>
> Sent: Sunday, October 10, 2010 9:36 AM
> Subject: [EVDL] torque formulae
>
>
> > Hi,
> >
> > Can someone please verify my formulas for calculating torque? These
> calcs
> > are supposed to figure out how much torque is needed to hold a vehicle
> > stationary at a particular grade, i.e. the point at which the motor
> > doesn't
> > turn and the vehicle neither rolls backwards or begins to climb. I
> know
> > that this would be really bad for a motor, but I think it shows the
> > minimum
> > effective torque needed to get the vehicle moving on a particular
> grade.
> > The rest of the calcs for acceleration and maintaining speed, I'll do
> > later.
> >
> > Peri Hartman
> >
> > (sorry if the columns don't line up - they are tab separated)
> >
> >
> > Inputs: (for tires: W%R e.g. 175/65R14: W=175mm, %=65, R=14")
> >
> > gross vehicle mass 1500 kg
> > incline 20 %
> > W 175 mm
> > % 65 %
> > R 14 inches
> > final drive axle ratio 3.53
> >
> > Calcs:
> > overall tire diameter 0.583 m W * % / 100 * 2 / 1000 + R *
> > 0.0254
> > force to maintain vertical pos. 2943 Nm mass * gravity * incline%
> > tire torque for vertical pos. 1716 Nm2 vertical force * tire
> > diameter
> > final drive torque for vert. pos. 486 Nm2 tire torque / final
> > drive ratio
> >
> > _______________________________________________
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> >
>
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