4 ms·

Size is not the issue. Electric motors can be made very small and very powerful. The issue is efficiency and handling the torque. Such a motor is useless if

Size is not the issue. Electric motors can be made very small and very powerful. The issue is efficiency and handling the torque. Such a motor is useless if its structure cannot handle the loads. Throw enough power into it and nearly any motor can break loose from its mounts and/or snap its drive shaft. Note too the coolant pipes. I suspect this motor cannot sustain such power for more than a minute or two. Small=light=low thermal mass=gets hot fast. As a general rule, electric parts become less efficient as they heat.

mcc1ane 5y ago
"Those peak power and torque figures are only available for 20 seconds, which is common among EV motors. After 20 seconds, the figures drop to 134 hp and 184 lb-ft of torque."
- sandworm101 5y ago
  It was the lower numbers that i question. I wonder how long it can sustain even those, and at what sacrifice to efficiency.
  - bluGill 5y ago
    Your typical car only uses about 20-30 horsepower when going down the road. However when coming off the line at a light it can use hundreds of horsepower for the 3-10 seconds it takes to get up to 60mph (for non-US readers, in the US all car reviews make a big deal of the 0-60mph times, and many magazines have tracks where they test that themselves. I'm guessing you would see 0-100mph here, which is only a slightly different top speed by I have no idea). Thus for car applications a motor that can deliver a lot of power for a short amount of time is useful and light weight is important. If this is light enough it might be worth the unsprung weight issues to put this in the wheels (particularly front wheels to get cheap 4x4) Automobiles are rather unusual in wanting and using a high amount of power in a burst and then needing a much smaller amount most of the time. Most equipment (including trucks when used as a truck) tend to need a lot more power all the time.
    - meepmorp 5y ago
      > I'm guessing you would see 0-100mph here, which is only a slightly different top speed kph?
      - bluGill 5y ago
        opps.
kube-system 5y ago
Yeah, other EV and hybrid motors are similarly impressively small for their power output.
- sandworm101 5y ago
  Because many of the parts that in an IC are part of the "engine" are on EVs not part of the "motor". All the piping for air/exhaust/cooling, all the wiring and control units, are included in IC engines. But such external systems on an EV are somehow conceptually dissociated from the motor. Its like looking at the block of a tiny rotary engine. Very small and powerful, but certainly not the whole picture.
  - kube-system 5y ago
    Even if you're just comparing a piston engine block/head, electric motors are tiny. Rotaries are close in power density if you're just comparing the block.
anentropic 5y ago
This was all in the article That max power and torque figure is limited to 30 seconds, presumably for thermal reasons. They claim the advantage it has over other small powerful motors is the output RPM here is already in a usable range where others need a gearbox.
LeifCarrotson 5y ago
Neither can an internal combustion, of course. When doing a max speed test, holding high horsepower output levels for a long time, an internal combustion engine will overheat quickly. That's true even with massive airflow over large liquid radiators, with coolant flowing through the casting along the cylinder walls - not to mention literally being a pump which moves cold air in and hot exhaust out at a rate of thousands of liters per minute. In both cases, it's fine that the power doesn't last, because it takes merely 10-20 horsepower (7.5-15 kW) to move an average car on a flat road at 60 MPH/100 km/h. To accelerate to that cruising speed in ten seconds takes about 180 horsepower/135 kW. I had the pleasure last week of working on an industrial vacuum pump installation with twelve 100-horsepower/75 kW electric motors - these guys: https://www.baldor.com/catalog/EM4400TS https://www.baldor.com/catalog/EM4400TS Don't look at the photo and think "Oh yeah, there's one of those hanging on the back of my dad's drill press." The shaft is the size of your wrist, not your finger. The casting is the size of an oil drum, and it is made from extremely dense cast iron and copper on a level that non-metalworkers probably don't understand: It weighs 1,200 lbs/550 kg. Size absolutely is the issue! That sort of motor would be a terrible powerplant for an electric vehicle: It MUST be made very much smaller and very much more powerful. It's made that way because an industrial motor needs to be able to dissipate 4.6% of that max rated 75 kW (acting as a 3,450W space heater) as heat while running at full power for days, covered in dirt and debris, spinning tirelessly in the desert sun, probably with a significant safety factor on all those numbers. Industrial motors are not the same as EV motors!
- sandworm101 5y ago
  >> holding high horsepower output levels for a long time, an internal combustion engine will overheat quickly. Every racecar in every 24-hour race. Every large boat/ship that runs at full throttle 24/7. Every large truck pulling a load up a hill. Every diesel generator that runs at full load for weeks. Modern IC engines can run flat-out for considerable periods of time. Counterintuitively, in many ways running at high power settings is easier on an IC engine than at lower fuel-efficient setting. Some pressures between parts are lower at higher RPMs. Total power/RPM is higher, but the energy involved in each rotation of a part is generally less. Oil moves more efficiently and doesn't get squeezed out as parts push against each other. And the ignition inside the cylinder is richer (ie cooler) when optimized for power rather than efficiency. Talk to anyone riding a Japanese sportbike. Those engines are far happier running flat-out on the track than sitting at idle in traffic.

mcc1ane 5y ago

"Those peak power and torque figures are only available for 20 seconds, which is common among EV motors. After 20 seconds, the figures drop to 134 hp and 184 lb-ft of torque."

sandworm101 5y ago
It was the lower numbers that i question. I wonder how long it can sustain even those, and at what sacrifice to efficiency.
- bluGill 5y ago
  Your typical car only uses about 20-30 horsepower when going down the road. However when coming off the line at a light it can use hundreds of horsepower for the 3-10 seconds it takes to get up to 60mph (for non-US readers, in the US all car reviews make a big deal of the 0-60mph times, and many magazines have tracks where they test that themselves. I'm guessing you would see 0-100mph here, which is only a slightly different top speed by I have no idea). Thus for car applications a motor that can deliver a lot of power for a short amount of time is useful and light weight is important. If this is light enough it might be worth the unsprung weight issues to put this in the wheels (particularly front wheels to get cheap 4x4) Automobiles are rather unusual in wanting and using a high amount of power in a burst and then needing a much smaller amount most of the time. Most equipment (including trucks when used as a truck) tend to need a lot more power all the time.
  - meepmorp 5y ago
    > I'm guessing you would see 0-100mph here, which is only a slightly different top speed kph?
    - bluGill 5y ago
      opps.

kube-system 5y ago

Yeah, other EV and hybrid motors are similarly impressively small for their power output.

sandworm101 5y ago
Because many of the parts that in an IC are part of the "engine" are on EVs not part of the "motor". All the piping for air/exhaust/cooling, all the wiring and control units, are included in IC engines. But such external systems on an EV are somehow conceptually dissociated from the motor. Its like looking at the block of a tiny rotary engine. Very small and powerful, but certainly not the whole picture.
- kube-system 5y ago
  Even if you're just comparing a piston engine block/head, electric motors are tiny. Rotaries are close in power density if you're just comparing the block.

anentropic 5y ago

This was all in the article That max power and torque figure is limited to 30 seconds, presumably for thermal reasons. They claim the advantage it has over other small powerful motors is the output RPM here is already in a usable range where others need a gearbox.

LeifCarrotson 5y ago

Neither can an internal combustion, of course. When doing a max speed test, holding high horsepower output levels for a long time, an internal combustion engine will overheat quickly. That's true even with massive airflow over large liquid radiators, with coolant flowing through the casting along the cylinder walls - not to mention literally being a pump which moves cold air in and hot exhaust out at a rate of thousands of liters per minute. In both cases, it's fine that the power doesn't last, because it takes merely 10-20 horsepower (7.5-15 kW) to move an average car on a flat road at 60 MPH/100 km/h. To accelerate to that cruising speed in ten seconds takes about 180 horsepower/135 kW. I had the pleasure last week of working on an industrial vacuum pump installation with twelve 100-horsepower/75 kW electric motors - these guys: https://www.baldor.com/catalog/EM4400TS https://www.baldor.com/catalog/EM4400TS Don't look at the photo and think "Oh yeah, there's one of those hanging on the back of my dad's drill press." The shaft is the size of your wrist, not your finger. The casting is the size of an oil drum, and it is made from extremely dense cast iron and copper on a level that non-metalworkers probably don't understand: It weighs 1,200 lbs/550 kg. Size absolutely is the issue! That sort of motor would be a terrible powerplant for an electric vehicle: It MUST be made very much smaller and very much more powerful. It's made that way because an industrial motor needs to be able to dissipate 4.6% of that max rated 75 kW (acting as a 3,450W space heater) as heat while running at full power for days, covered in dirt and debris, spinning tirelessly in the desert sun, probably with a significant safety factor on all those numbers. Industrial motors are not the same as EV motors!

sandworm101 5y ago
>> holding high horsepower output levels for a long time, an internal combustion engine will overheat quickly. Every racecar in every 24-hour race. Every large boat/ship that runs at full throttle 24/7. Every large truck pulling a load up a hill. Every diesel generator that runs at full load for weeks. Modern IC engines can run flat-out for considerable periods of time. Counterintuitively, in many ways running at high power settings is easier on an IC engine than at lower fuel-efficient setting. Some pressures between parts are lower at higher RPMs. Total power/RPM is higher, but the energy involved in each rotation of a part is generally less. Oil moves more efficiently and doesn't get squeezed out as parts push against each other. And the ignition inside the cylinder is richer (ie cooler) when optimized for power rather than efficiency. Talk to anyone riding a Japanese sportbike. Those engines are far happier running flat-out on the track than sitting at idle in traffic.