[Diy_efi] Proportioning valves

[Becker, Damon Damon]

Most Toyotas have this.  The trucks do, and so does my independant suspension 93 Camry.  It's a fantastic idea!  

	-----Original Message----- 
	From: diy_efi-bounces at diy-efi.org on behalf of dan at w3eax.umd.edu 
	Sent: Sat 11/25/2006 5:05 PM 
	To: diy_efi at diy-efi.org 
	Cc: 
	Subject: [Diy_efi] Proportioning valves
	
	


	My guess is the primary purpose of the regulator is safety.  If the rear
	wheels were to lock up before the fronts in an MR2, most drivers would
	cause disasterous consequences.  As a result, they may have intentionally
	been overly conservative in the settings to ensure that this never
	happens.
	
	I have a VW and I'm aware of the VW load-sensing pressure regulator.  It
	was certainly a darn clever idea.  Unfortunately I don't have a solid axle
	like the VW.  I suppose its possible I could rig it up some how onto the
	strut assembly.
	
	I just thought it would be an interesting project to try a quasi-ABS
	system.  I'm not real clear on how ABS works though.  It was my
	understanding the pump creates a huge amount of excess pressure and then
	the valve block is some how used to control the pressure at the wheels.  I
	wasn't clear whether or not its a PWM in order to maintain a specific
	pressure or if its just a too-much pressure, no pressure, too-much
	pressure, no pressure, too-much, etc.
	
	I don't really see why a pump is needed if you just use the pressure
	applied by the foot and modulate the pressure so that the moment it locks
	up, you alleviate pressure (say 70% of pre-lock pressure or whatever it
	takes to let the wheel spin), then build back up to 95% of pre-lock
	pressure, then slowly walk upward until it locks again and repeat.  (I've
	also wondered if there is someway to sense lockup before it happens.
	
	I realize this isn't EFI, but it is automotive electronic design so I
	figured people here might be interested.
	
	dan
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