Lil4X
Elio Addict
^^ I think those are valid points. Turning the compressor at engine speed introduces a lot of mechanical losses when the job of maintaining cabin temperature is solely handled by a variable expansion valve. Most of the time a fixed displacement compressor, if it is calibrated to cool the cabin at speeds just off idle, is going to by hammering away against the expansion valve at 2000 rpm and up. That's a waste of energy - and makes life miserable for the rotating components in the compressor, essentially recycling the same liquids at high speed.
Now an electric compressor can produce the same pumping efficiency as a variable-displacement compressor, but can also be throttled up and down to meet the demand of the system - that is controlled by pressure without the swash plate and pilot valve that has to select its angle to the shaft, thus altering the stroke of the compressor's pistons.
No, there aren't any free lunches here - that electrical energy to drive the compressor has to come from the alternator - but the battery can act as a buffer here to mitigate the electrical load as the compressor is cycled on and off. At the same time the mechanical shock as the magnetic clutch is engaged at speed on a conventional engine-driven compressor - often starting the compressor suddenly against high head pressure - can be eased by an electric motor slowly ramping up the torque on the compressor.
I'm no expert, but that just seems like a much better solution. Electric motors are far cheaper than they used to be and can be integrated into the compressor itself to reduce the number of parts - and potential points of failure. Now, the cost advantage of such a system needs to be reviewed, but I see it as a matter similar to the selection of a cam-drive chain over a belt. OK, the belt is a lot cheaper, but in the long run, it's going so save the owner a lot of maintenance costs.
Now an electric compressor can produce the same pumping efficiency as a variable-displacement compressor, but can also be throttled up and down to meet the demand of the system - that is controlled by pressure without the swash plate and pilot valve that has to select its angle to the shaft, thus altering the stroke of the compressor's pistons.
No, there aren't any free lunches here - that electrical energy to drive the compressor has to come from the alternator - but the battery can act as a buffer here to mitigate the electrical load as the compressor is cycled on and off. At the same time the mechanical shock as the magnetic clutch is engaged at speed on a conventional engine-driven compressor - often starting the compressor suddenly against high head pressure - can be eased by an electric motor slowly ramping up the torque on the compressor.
I'm no expert, but that just seems like a much better solution. Electric motors are far cheaper than they used to be and can be integrated into the compressor itself to reduce the number of parts - and potential points of failure. Now, the cost advantage of such a system needs to be reviewed, but I see it as a matter similar to the selection of a cam-drive chain over a belt. OK, the belt is a lot cheaper, but in the long run, it's going so save the owner a lot of maintenance costs.