2012 TCH Humming-whining sound - Toyota Nation Forum : Toyota Car and Truck Forums


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Old 06-04-2012, 10:47 PM   #1 (permalink)
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2012 TCH Humming-whining sound

I didn't notice it on the test drive but (especially) when the car is decelerating, the car makes a whining sound that descreases in pitch with descreasing speed. It kind of sounds futuristic in an obtrusive way. Its giving away my age but I feel like Woody Allen in Sleeper... in a car of the future.

Prius owners that I have talked to don't know what I'm talking about and I personally don't know any other TCH owners.

So my questions are...
1. Is this typical?
2. If so, why does a TCH make it but not a Prius?
3. What is actually making that sound?

Thanks
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Last edited by Larbo; 06-04-2012 at 10:48 PM.
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Old 06-04-2012, 11:31 PM   #2 (permalink)
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I think its the sound of the Hybrid EV mode, Prius has them too. To tell you the truth, I don't notice/hear them anymore, I recall hearing them when test drove both TCH and Prius V.

May be mine is already broken in and sound is gone ?

I'll start paying attention and listen now. Tomorrow AM.
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Old 06-04-2012, 11:53 PM   #3 (permalink)
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Great. Looking forward to your findings. I will be driving the car a lot tomorrow (wife usually has it) so I will play with the modes a bit.
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Old 06-05-2012, 12:08 AM   #4 (permalink)
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The sound you hear is the generator on the new '12 Camry hybrid that's located in the tranny case. The generator is stepped up some over the earlier models to charge the traction battery more quickly. I hear it when coasting around 30 to 40 mph at night when their is no wind. I don't mind the little bit of occasional whine as it's saving me gas money.

Here are some interesting facts about the new '12 TCH Transaxle.

Hybrid Transaxle and Inverter. The 2012 Camry Hybrid features an all new hybrid transaxle. Like all Toyota hybrid transaxles, it is a series-parallel design with two motors: MG1, which primarily acts as an engine starter, a generator, and a motor to modulate the gearing ratio of the engine; and MG2, which primarily functions as the vehicle's traction motor, as well as a generator during regenerative braking. Both motors are driven by three-phase current up to 650V AC.
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Old 06-05-2012, 08:40 AM   #5 (permalink)
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Very interesting!

I hear the whine too. I've got the 100,000 mile extended warranty, so anytime I hear a strange noise (and there are a few of them on this car), I just tell myself, "Not my problem."

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Old 06-05-2012, 08:41 AM   #6 (permalink)
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On another note, when I open the driver's side door, there's a long, monotone groan that comes from the engine compartment.

Any idea what that is?
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Old 06-05-2012, 10:04 AM   #7 (permalink)
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Quote:
Originally Posted by Larbo View Post
I didn't notice it on the test drive but (especially) when the car is decelerating, the car makes a whining sound that descreases in pitch with descreasing speed.

3. What is actually making that sound?
I'm still waiting on delivery of mine, but I did hear a whine sound on the test drive. It seemed most noticeable about 25 mph when coming up to a stop. At about the same time I think I heard the gas engine stop, so it got quite quiet except for the whine.

If you look at the simulation below, set the MG2 slider at 25 mph, and the ICE (internal combustion engine) at minimum speed of 1000 rpm. You will see the MG1 is around zero rpm. Now drop the ICE rpm to zero to simulate the engine stopping. You will see that the MG1 goes in reverse to about 3800 rpm quite suddenly. I'm guessing that is where the whine comes from.

Hybrid Synergy Drive Simulator

This simulator is for a Prius which is essentially the same design. So not sure why it would be more audible on a Camry. Perhaps the timing as to when the ICE drops out is different and the rpm of MG1 goes higher still. I'm just guessing at 25 mph.
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Old 06-05-2012, 01:36 PM   #8 (permalink)
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Quote:
Originally Posted by rosethornil View Post
On another note, when I open the driver's side door, there's a long, monotone groan that comes from the engine compartment.

Any idea what that is?
One may be the ABS brake system pumping up. The other could be the fuel evaporation system leakage check. This test can be run as late as 5 hours after you turned off your hybrid system.
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Old 06-09-2012, 12:12 AM   #9 (permalink)
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I have learned a little more about the Camry Hybrid e-CVT since my previous post in this thread. While the Prius appears to have a single planetary gear set, the Camry has two sets of planetary gears. The purpose of the second set of planetary gears is to provide a gear ratio of about 2.5 to the MG-2. MG-2 is the main traction motor and generator for regenerative braking. The net result if I understand it correctly, is that the MG-2 runs at about 2.5 times the RPM in the Camry compared to the MG-2 in the Prius.

The purpose seems to be to increase the torque of the motor drive to make it more suitable for a heavier vehicle. The side effect is that MG-2 can hit 14,000 RPM. So it would appear that could explain the noise difference between the Prius and the Camry when it is in regenerative braking mode.

I think functionally you can still use that simulator I provided in the previous link, but the RPM of MG-2 needs to be increased by 2.5 times to simulate the Camry e-CVT.

If you want to dig into it, have a look at page 2-7, and the graphic on 2-8, at the link below to see what it looks like.

Toyota 2007 Camry HEV Technology Report

I don't understand why the graphic quality is so poor in this report, and if anyone has a link to a better quality one, I would be thankful to get it.
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Old 06-09-2012, 04:43 AM   #10 (permalink)
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The graphics are really fuzzy, but that is one of the most succinct and well-worded explanations of the Camry hybrid system that I have seen.

Thanks very much for posting that.

On another note, I would *love* to know the major electrical/mechanical differences between the 2007 and the 2012.

And does anyone know where our hybrids are made? Are some of them made in Japan?

Rose


Quote:
Originally Posted by Ron AKA View Post
I have learned a little more about the Camry Hybrid e-CVT since my previous post in this thread. While the Prius appears to have a single planetary gear set, the Camry has two sets of planetary gears. The purpose of the second set of planetary gears is to provide a gear ratio of about 2.5 to the MG-2. MG-2 is the main traction motor and generator for regenerative braking. The net result if I understand it correctly, is that the MG-2 runs at about 2.5 times the RPM in the Camry compared to the MG-2 in the Prius.

The purpose seems to be to increase the torque of the motor drive to make it more suitable for a heavier vehicle. The side effect is that MG-2 can hit 14,000 RPM. So it would appear that could explain the noise difference between the Prius and the Camry when it is in regenerative braking mode.

I think functionally you can still use that simulator I provided in the previous link, but the RPM of MG-2 needs to be increased by 2.5 times to simulate the Camry e-CVT.

If you want to dig into it, have a look at page 2-7, and the graphic on 2-8, at the link below to see what it looks like.

Toyota 2007 Camry HEV Technology Report

I don't understand why the graphic quality is so poor in this report, and if anyone has a link to a better quality one, I would be thankful to get it.

Last edited by rosethornil; 06-09-2012 at 04:57 AM.
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Old 06-09-2012, 06:26 AM   #11 (permalink)
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Originally Posted by rosethornil View Post
And does anyone know where our hybrids are made? Are some of them made in Japan?
Rose
Mine is made in Kentucky, I think. Open your driver's door and the white sticker will say where yours is made. I would hope the major components come from Japan.
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Old 06-09-2012, 06:33 AM   #12 (permalink)
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Quote:
Originally Posted by Larbo View Post
I didn't notice it on the test drive but (especially) when the car is decelerating, the car makes a whining sound that descreases in pitch with descreasing speed. It kind of sounds futuristic in an obtrusive way. Its giving away my age but I feel like Woody Allen in Sleeper... in a car of the future.

Prius owners that I have talked to don't know what I'm talking about and I personally don't know any other TCH owners.

So my questions are...
1. Is this typical?
2. If so, why does a TCH make it but not a Prius?
3. What is actually making that sound?

Thanks
Hybrids in EV will probably soon be required to emit some kind of sound for visually impaired pedestrians. Since this "subway train" sound can be heard on the outside of the vehicle at low speeds, I suspect it may not have been engineered out of the design.

I agree with the above posters, it is probably MG2.
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Old 06-09-2012, 10:14 AM   #13 (permalink)
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Quote:
Originally Posted by rosethornil View Post
On another note, I would *love* to know the major electrical/mechanical differences between the 2007 and the 2012.
And does anyone know where our hybrids are made? Are some of them made in Japan?
For whatever reason, the most detailed information on the new features of the 2012 Camry Hybrid seem to originate in Australia. I know not all detailed interior trim details are the same as the North American vehicle, but I assume the power train is the same. Here is a good detailed summary that seems to originate with Toyota in Australia. I found it when searching for information on the "compound planetary gear system". North American reviewers and Toyota itself seem to be very silent on the fact that the Camry e-CVT is different than the Prius.

2012 Toyota Camry Hybrid Press Kit

Here are some things I picked out:

"Camry Hybrid's driveline has increased efficiency, including new low-friction bearings, improvements to the electric motor/generators and improved control of the electronic continuously variable transmission."

"Two important performance features are shared with the petrol Camry engine: a long-port intake manifold, which saves weight, reduces noise and boosts performance; and a long-branch manifold exhaust, which also boosts torque and hence performance. Friction-reduction measures include roller rockers and a variable-output oil pump. A cooled exhaust-gas recirculation system also reduces emissions."

"Camry Hybrid's new P314 transaxle includes two 650-volt AC motor/generators. One acts primarily as a generator and the other as an electric traction motor, delivering a maximum 105kW of power and 270Nm of torque. Improvements in the P314 transaxle include new control software, new low-friction bearings to boost driving performance and economy, and an improved flywheel damper to further reduce NVH."

(Goggle searches to get more detail on the P314 transaxle have got me nowhere...)

Currently I believe all North American Hybrids are made in Kentucky. Not sure if they have an engine assembly plant there too, or if that comes from Japan. There was some talk the new 2012 Hybrid would be so popular that the Kentucky plant would not be able to meet demand, and Toyota were seeking approval to import Japanese made ones. Don't think that happened.
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Old 06-09-2012, 10:40 AM   #14 (permalink)
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If your VIN # (in your driver side window, look down and see a metal tag with #s) has a U in the 11 digit it was made in Kentucky.

Here is a link to the breakdown which shows what country, plant, etc

http://en.wikibooks.org/wiki/Vehicle...yota/VIN_Codes
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Old 06-09-2012, 12:22 PM   #15 (permalink)
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Quote:
Originally Posted by rosethornil View Post
The graphics are really fuzzy, but that is one of the most succinct and well-worded explanations of the Camry hybrid system that I have seen.

Thanks very much for posting that.

On another note, I would *love* to know the major electrical/mechanical differences between the 2007 and the 2012.

And does anyone know where our hybrids are made? Are some of them made in Japan?

Rose

All (100%) of the Camry Hybrids marketed here in the US are made in Georgetown, Kentucky. However, only 82% of components are from American vendors, which could mean that there are parts from other countries, just imported by an American company. Also, that 18% non-American is most probably the powertrain from Japan, although not specifically described. Camrys are also made in Altona, Victoria, Australia, and the original factory in Toyota City, Japan, most probably for other (local) markets. I don't think the Kentucky plant exports cars made there to other countries.

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