2001 Prius Inverter Pump

I have two gen 1 pumps sitting in my garage with failed bearings.

 

Cool!

I'm interested in understanding what went wrong. Send a PM and we can 'do a deal.'

Bob Wilson

 

Why do you think the failure is in the bearings?

 

"Detecting a pump failure is an interesting challenge but could we just listen for it by turning on to ignition and listening for it?"

I've seen other threads where they could hear the pump whine, but still no flow. Regardless if the pump makes the noise or not, air in sys., blockage, etc.. -no flow = no inv.
More and more, I pop the hood just after we get back from a ride, all warmed up and ready, probably the best time to check since cold they seem to always run -it's hot when they seem to quit, and look/listen for the turbulence in the tank before switching off. Our 03 has never had this problem yet however it could happen anytime. Tank flow sensor I think I'll try it.

 

Sounds like a neat project. Good luck!

Bob Wilson

 

Here's a possibility.
GEMS Water Flow Switches Sensors for Liquid LOT of 2! - eBay (item 160391587132 end time Aug-30-10 09:13:05 PDT)

 

Interesting but I would like to check the part specs. I filled up with gas this evening and noticed I could not hear the pump easily. I opened the reservoir and saw the flow but I was disappointed about not hearing the pump.

I think you may be on to something useful. It would be helpful if we can get some failed pumps for testing.

In the short term. I'll see if we can get some existing electrical sensor data. For example inverter pump current for a working unit. Also, the inverter temperature values.

It is a shame that so many visitors don't give a sh*t about keeping our NHW11s on the road for affordable costs. But you know, sometimes there are 'inconvient truths'.

Bob Wilson

 

Just a quick follow-up:

• G904048020 - ZVW30 inverter pump, new price ~$200, trying for a salvage part.
• Ordered Schematics - just about $230, this may give a clue about how the variable speed pump is supposed to work or at least identify the wires and their interfaces.

That $50 part (or two for $50) looks promising. I finally saw the datasheet and other than the 'max 100C' operating limit, I would prefer 125C given it will be in the engine compartment, it is probably OK. But I could not find the flow-rate in the data sheet that corresponded to that part. Perhaps a question to the seller?

Also ask them about engine coolant exposure in the vehicle engine compartment. See if they know of any potential problem from the sheet inside the box?

Bob Wilson

 

Yes it says water, fuel, etc.. so I would think coolant would be little more than water to the sensor. Interesting but the 100C limit I almost never see on my 03. The highest inv. temp I've seen so far is 88C and that was on a very hot day after driving it for an hour, MG2 temp got up to 78C that day as well via the SGII. I also sometimes -but not always hear the pump sound, especially when other cars are around it is difficult at best to hear. I'm getting into the habbit of just popping the hood and have a quick look at the flow just before shut down. This way everything is up to temp., and if anything is prone to fail it would be then I think, but ease of mind is worth a lot too.

 

Actually it doesn't say anything about fuels but who cares. Notice it says not good for oils, and they recommend 50micron filtering.
I will next attempt to get more info about coolants from the company.

1. NO switches in No Flow condition are standard; please contact us for NC models.
2. The device is designed to provide Flow/No Flow sensing. Tabulated set points specify maximum
contact closure thresholds on increasing fluid flow. Re-establishment of a Normally Open contact
occurs on decreasing fluid flow between set point and no flow.
3. Flow settings are based on a vertical position (inlet port down), using water at +20°C on increasing
flow. Some variation in set point actuation will occur in other mounting orientations.
4. Use of 50 micron, or better, filtration is required.
5. Not recommended for use with oils.

 

It will be interesting to see your flow-sensor approach. I've still keep thinking of alternative sensor approaches:

1. motor current - usually a stalled motor will exhibit higher current draw. But in this case, the electronics of the brushless design may or may not show this pattern. If we could get the two failed motors statultra reports having, we could do some measurements.
2. inflow/outflow temperature - a pair of thermistors feeding a comparator could drive a red LED that changes to green as a positive temperature change occurs. Bonded to the inverter coolant or inverter radiator, this is the same principle a MAF sensor uses.
3. inverter temperature warning LEDs - upon detecting high temperature, raise red lights.

Don't stop on the flow sensor but I just wanted to share some thoughts.

Bob Wilson

 

I have placed an inquiry to the sensor company about coolants. Another thing to consider is the fact that if this sensor needs filtering to 50micron or better that means adding a filter inline to the coolant flow as well. I wonder if that would be too much resistance in this system.. possible even add to the pump failure rates. Not sure about this yet but the flow rates look correct of between .2 and 3.8 Liters/Min. I think the prius is around 1.5 L/m so right in the middle which is great for us. Will find out more soon.

 

Yea! The 2010 electrical manual arrived!

The 2010 water pump has four wires:

1. Ground
2. NWP signal, probably TTL speed control bit
3. SWP signal, probably second TTL speed control bit
4. SWP, 10A, power

So it looks to fairly straight forward. Now to get the part, used hopefully, but new if I have to. I'll set it up on the bench first with a coolant loop and measure the current at different combinations of NWP and SWP.

I try capping the pump and monitoring the current at different speeds. I'll also see if it is a steady current draw or shows evidence of switching.

Once I get my old inverter pump out, I'll do the same set of tests. This will hopefully give us a clue as to what circuit monitoring might make an effective, failure detector.

NOTE: Ebay has a number of salvage, inverter pumps. Knock on wood, I'll get one for bench testing but I was surprised to find a 'new' NHW11 inverter pump going for a similar price for the ZVW30 pump. Clearly the ZVW30 pump is an improved design.

Bob Wilson

 

I have a used NHW11 inverter pump plumbed with ID 3/4" tubing connected to a power supply:

• feel the pump vibration - subtle, it is there
• 12.35-14.81 VDC - as it runs, we're seeing significant variation in the voltage. I configured the power supply for 13.8 V, 7.8 A, so the motor is generating a significant amount of variable, back EMF.
• .89-1.33 A - it runs pretty warm, ~16-17 W

One problem is the motor has no access to the coolant loop. So when it stops, the latent heat has plenty of opportunity to 'cook' the bearings. The vehicle frame is the heat-sink for the motor.

So I'm thinking a small ohm, current sensor, say 0.05-0.1 ohm, capacitive coupled to a transistor amplifier and LED. The LED should flash indicating the motor is operational.

Another option would be a low impedance transformer that drives a diode protected, LED. Again, the idea is to detect the variable current of a running motor. If the motor fails, the LED is dead.

Tapping the inverter coolant pump could be done at IG2 relay located in the engine compartment J/B fuse box on the driver side. An audio impedance matching transformer should work very nicely. But I have some other ideas to test:

1. iron wire or thin plate sensor - fitting around the relay lines, a detection loop handles current variation sensing and/or driving the LED. A small, thin iron wire (aka., music wire) may be enough.
2. detect dV across relay contacts - obviously it needs to ignore an open relay but it may be possible to detect the dV from the latent relay contact resistance.

Now to do a little field work.

Bob Wilson

 

i took the pump apart a long while ago, and behind the butile rubber coating on the side there is a circuit board, with what looks like temperature protection. the impellers on the pump was in great condition, to get access to the motor i had to use some good work to get in there, it was encased in plastic. once i got it open i tried to spin the motor freely which was somewhat hard to do as expected but there was a feeling of grinding inside the plastic motor housing. The problem could be that since I had used this pump in this error condition for a good while it could damage the bearings.

now bearing failure may not be the result of the component but the driver not fixing the problem in time

 

Brushless or commutator motor? PM rotor?

I'm used to commutator motors having significant, variable back EMF which is why I was surprised to see the effect on my power supply. Given the expected service life, brushless would make sense.

Bob Wilson

 

The 2010 water pump has four wires:

1. Ground
2. NWP signal, probably TTL speed control bit
3. SWP signal, probably second TTL speed control bit

SWP, 10A, power

Nice so it runs at 1.3A and hot ..that doesn't surprise me.

I'm thinking that 2&3 may be sense lines that tell the system that it is in fact running. I mean why would there be feedback for a speed control?
It's either on or off right?

 

I don't have a 2010 inverter pump, yet. The new car features claims it is a 4-speed unit so two bits covers it nicely.

I'm monitoring the 'usual suspects' looking for a salvage inverter pump. But if I decide to act anyway, I can get a new one for just under $200 . . . pretty much the same price as the NHW11 pump.

I'll photo 'blueprint' the NHW11 pump, do some more electrical tests, and then we'll be ready for phase II. <grins>

I haven't seen the vehicle mount but I was thinking maybe a thin piece of aluminum sheet bent to provide fins might help. Anything to help it run less hot.

Bob Wilson

 

Here are my photos of the NHW11 cabin heater pump:


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The pump nipples accept a 3/4" ID hose held with a standard hose clamp.

We might be able to use this pump as an alternate for the belt driven, water pump. Remove the thermostat to increase flow and use this pump driven by the ICE thermostat to circulate coolant.

BTW, I found a supplier for a used NHW11 inverter pump. It should be here the next of next week and I'll work up the specifications.

Bob Wilson

 

OWCH!

I just learned this may be the heater coolant pump, not the inverter coolant pump. This goes a long way to explaining the 3/4" nipples. The part numbers on the tag are:

• 87260-47020 (first number)
• 064100-0771 (second number)

After checking with Champion and what I can find in the maintenance manual, I'll contact the seller and see what we can do.

I'll be changing the ICE and transaxle oil this week so I'll take some time to find and photo the coolant pump.

Bob Wilson