cooling systems auto 1 if you did your homework, this will make more sense! if you didn’t, get it...
TRANSCRIPT
COOLING SYSTEMSAUTO 1
If you did your homework, this will make more sense!
If you didn’t, get it turned late tomorrow.
We will take notes in a little bit.
•WHERE DOES THE HEAT COME FROM?
•HEAT CAUSES EXPANSION WHICH CAUSES?
•PRESSURE PUSHES PISTON DOWN WHICH MAKES THE WHEELS GO ROUND AND ROUND
•PRESSURE!
ENERGY……….
THAT’S RIGHT, BURNING FUEL
• FUEL IS CHEMICAL ENERGY– WHEN BURNED COVERTS TO...
• THERMAL ENERGY (HEAT)– WHICH CAUSES EXPANSION
(PRESSURE)– WHICH COVERTS TO…
• MECHANICAL ENERGY– WHICH WE USE TO MOVE THINGS
• THIS IS ENERGY CONVERSION
ENERGY CONVERSION?• REMEMBER, YOU CAN’T CREATE OR
DESTROY ENERGY• YOU CAN ONLY CHANGE ITS FORM
– THIS IS ENERGY CONVERSION
• IN OTHER WORDS, THERE IS ONLY SO MUCH ENERGY HERE ON EARTH AND WE CAN’T ADD TO IT OR RUN OUT OF IT. NEVER USE IT UP!
• WOW
WE HAD BETTER WRITE THIS DOWN IN OUR FUEL NOTES.
• FUEL IS CHEMICAL ENERGY– WHEN BURNED COVERTS TO...
• THERMAL ENERGY (HEAT)– WHICH CAUSES EXPANSION
(PRESSURE)– WHICH COVERTS TO…
• MECHANICAL ENERGY– WHICH WE USE TO MOVE THINGS
• YOU CAN’T CREATE OR DESTROY ENERGY, YOU CAN ONLY CHANGE ITS FORM!
• ITS FORM IS CHANGED BY A CHEMICAL REACTION.
• THE MOST COMMON TYPE OF CHEMICAL REACTION IS COMBUSTION
• LETS MOVE ON
LETS CONCENTRATE ONWE HAD BETTER WRITE THESE DOWN IF WE DON’T ALREADY KNOW THEM
• HEAT IS THE RAPID MOVEMENT OF ATOMS OR MOLECULES IN A SUBSTANCE ABSOLUTE 0 IS-460F (-273C)
• HEAT IS A FORM OF ENERGY
• HEAT IS MEASURED BY……….– TEMPERATURE
• DEGREES IN FAHRENHEIT OR CELSIUS
– BTU’s• VOLUME OF HEAT
HEAT
BTU,s ????
• BRITISH THERMAL UNIT– ONE (1) BTU WILL RAISE THE
TEMPERATURE OF ONE (1) POUND OF WATER ONE (1) DEGREE FAHRENHEIT (F)
WHAT IS THE DIFFERENCE BETWEEN TEMPERATURE AND
BTU,s ?• TEMPERATURE IS THE DEGREE OF
HEAT OR HOW HOT.– FOR EXAMPLE, A MATCH MIGHT BURN AT
400 DEGREES F.
• BTU IS THE VOLUME OF HEAT OR HOW MUCH, BUT NOT TEMPERATURE.– EXAMPLE, THE AMOUNT HEAT IT TAKES
TO HEAT THIS ROOM, OR RAISE THE TEMPERATURE OF THIS ROOM
• COMBUSTION TEMPERATURES CAN REACH UP TO __________ DURNING THE COMBUSTION PROCESS. PAGE 92 OF YOUR HOMEWORK.
• THINK ABOUT THIS QUESTION BEFORE YOU FORM AN ANSWER. WOULD YOU WANT THE VOLUME OF HEAT FROM ONE 6000 DEGREE F POWER STROKE TO HEAT THIS ROOM?
• NOT IN THE WINTER TIME
GALLON OF GASOLINE• ONE GALLON OF GASOLINE HAS
APPROXIMATELY 115,000 BTU,s.• THAT MEANS THE AVERAGE GALLON OF
GASOLINE HAS THE ENERGY TO RAISE THE TEMPERATURE OF ONE POUND OF WATER 115,000 DEGREES F. (IMPOSSIBLE) OR…
• RAISE 115,000 LBS OF WATER ONE DEGREE F. OR
• RASIE 1,150 LBS OF WATER (ABOUT 150 GALS.) 100 DEGREES F.
• OTHER FUELS HAVE DIFFERENT BTU,s
• DIESEL HAS APPROXIMAELY 135,000 BTU,s PER GALLON
• ALCOHOL HAS APPROXIMATELY 85,000 BTU,s PER GALLON
IF TODAYS VEHICLES CAN AVERAGE 20 MILES PER GALLON NOW USING JUST 15% OF THE ENERGY IN A GALLON OF FUEL...
WHAT KIND OF MILAGE COULD THEY GET IF WE COULD IMPROVE
IT TO 50% OF THE ENERGY IN A GALLON OF FUEL???
• TODAY – 20 MPG USING 15%
OF ENERGY
• TOMMOROW??– 70 MPG USING 50%
OF ENERGY
MILES PER GALLON AVERAGES
SO WHY DO WE HAVE TO REMOVE 35% OF THE HEAT WITH A COOLING SYSTEM?
•LIMITED BY CURRENT MATERIAL TECHNOLOGY
•LIMITED BY CURRENT LUBRICATION TECHNOLOGY
WE JUST PAID BIG MONEY TO BUY FUEL TO CREATE HEAT!
CYLINDER WALL TEMPERATURE MUST BE
KEPT BELOW 500 DEGREES F.WHY?
OIL BREAKS DOWN (BURNS)
CAN YOU SAY DRY FRICTION?
LETS REVIEW
• CAN’T DESTROY OR CREATE ENERGY– ENERGY CONVERSION
• SIX TYPES OF ENERGY– IN AUTOMOBILES WE USE, ELECTRICAL,
THERMAL, CHEMICAL, RADIANT, AND MECHANICAL. DON’T USE NUCLEAR
• HEAT– WHAT IT IS AND HOW IT IS MEASURED– DIFFERENCES BETWEEN TEMP AND BTU
APPROXIMATELY 15% OF THE ENERGY IN GASOLINE
IS USED TO MOVE THE CAR.
LOST TO EXHAUST
LOST TO COOLING
FRICTIONAL LOSES
WHICH TYPE OF HEAT TRANSFER DO WE USE IN
AN ENGINE?
• DURING COMBUSTION– EXPLOSION WOULD HAVE TRANSFER
THRU RADIATION TO HEAD, CYLINDER WALL, AND TOP OF PISTON
– ALSO TRANSFER THRU CONVECTION TO HEAD, CYLINDER WALL AND TOP OF PISTON and….
• FROM INSIDE OF CYLINDER WALL AND HEAD…– HEAT TRANSFER THRU CONDUCTION TO
OUTSIDE OF CYLINDER WALL AND HEAD
• FROM OUTSIDE OF CYLINDER WALL AND HEAD…– HEAT TRANSFER THRU CONVECTION
• TO SURROUNDING AIR ON AIR COOLED• TO SURROUNDING LIQUID IN WATER JACKET
ON LIQUID COOLED
FORCED DRAFT
USUALLY USED ON ENGINESTHAT ARE STATIONARY OR
THAT AREN’T MOVEDVERY FAST
HAS A FAN TO FORCE AIRACROSS ENGINE
USES SHROUDS TO DIRECTAIR TO PROPER PLACES
ALL YOUR ENGINES AREFORCED DRAFT
YOUR FLYWHEEL ACTS ASTHE FAN
LETS ADD THAT TO OUR ENGINE PARTS LIST PURPOSES FOR THE
FLYWHEEL
A. TO KEEP ENGINE MOVING THRU NON POWER STROKES
B. ACTS AS A FAN FOR THE COOLING SYSTEM
C. WE WILL GET
D. C. AND D. LATER
NOTICE THE FINS.
WHAT WOULD HAPPEN IF WE BROKE ONE OFF?
THESE ARE CALLED HEAT DISAPATING FINS.
THEY ADDSURFACE AREA
SO MOREHEAT CAN
BE REMOVED.
LETS LOOK AT AN OPEN DRAFT AIR COOLED ENGINE
HAS NO FAN
ENGINE MUST MOVETHROUGH AIR FOR
AIR MOVEMENT
MAY OR MAY NOT HAVESHROUDS
TYPCIAL AIR COOLEDMOTORCYCLE ENGINE
REMEMBER ENGINEMUST MOVE THROUGH
AIR TO GET PROPERCOOLING ON THE
OPEN DRAFT DESIGN!
WITHOUT AIR MOVEMENT,ENGINE CAN OVERHEAT.
ESPECIALLY ON HOT DAYS.
MUST HAVE HEATDISAPATING FINS AS WELL
LETS MAKE SURE WE HAVE THIS IN OUR NOTES
• OPEN DRAFT– NO FAN, ENGINE HAS TO MOVE THRU
AIR FOR COOLING
• FORCED DRAFT– HAS FAN TO FORCE AIR FLOW FOR
COOLING
SO WHAT DO WE NEED TO DO TO TAKE CARE OF AIR COOLING SYSTEMS ?
• KEEP FINS CLEAN OF GREASE AND DEBRIS– CLEAN WITH SOLVENT OR HOT SOAPY
WATER OR CAN CLEAN WITH DEGREASERS– DON’T CLEAN WHILE ENGINE IS HOT– MAY HAVE TO REMOVE SOME SHROUDS TO
GET TO ALL FINS
• KEEP ALL SHROUDS IN PLACE DURING USE
PURPOSE OF COOLING SYSTYEM
BETTER GET THIS IN OUR NOTES
• KEEP ENGINE AT MOST EFFICIENT OPPERATING TEMPERATURE– TOO COLD = WASTED ENERGY (BTU)– TOO HOT = LOSS OF LUBRICATION
• AIR COOLED IS NOT ACCURATE– DESIGNED TO OVERCOOL
• LIQUID COOLING IS DESIGNED TO GET THE ENGINE TO WARM UP QUICKLY YET NOT OVERHEAT
WHAT IS THE LIQUID?
• COOLANT IS MADE UP OF A MIXTURE OF WATER AND ANTIFREEZE
COOLANTLETS GET THIS IN OUR NOTES
LETS REVIEW• ENERGY
– ENERGY CONVERSION– TYPES OF ENERGY
• HEAT– WHAT IT IS AND HOW IT IS MEASURED– DIFFERENCES BETWEEN TEMP AND BTU
• WHY WE HAVE COOLING SYSTEMS• AIR COOLING
– TYPES– FINS, SHROUDS, AND FANS– MAINTENANCE
FOUR PURPOSES OF USING ANTIFREEZE
1. LOWER FREEZING POINT OF WATER
PURE WATER = 32F
25% ANTIFREEZE = 10F
50% ANTIFREEZE = -34F
68% ANTIFREEZE = -92F
PURE ANTIFREEZE = -10F
FOUR PURPOSES OF USING ANTIFREEZE
1. LOWER FREEZING POINT OF WATER
2. RAISE BOILING POINT OF WATER
WATER BOILS AT 212F
25% ANTIFREEZE BOILS AT 218F
50% ANTIFREEZE BOILS AT 225F
PURE ANTIFREEZE BOILS AT 320F
FOUR PURPOSES OF USING ANTIFREEZE
1. LOWER FREEZING POINT OF WATER
2. RAISE BOILING POINT OF WATER
3. PREVENT RUST/CORROSION AND DEPOSITS
IS AN ADDITIVE THAT EVENTUALLY NEEDS REPLACED
FOUR PURPOSES OF USING ANTIFREEZE
1. LOWER FREEZING POINT OF WATER
2. RAISE BOILING POINT OF WATER
3. PREVENT RUST/CORROSION AND DEPOSITS
IS AN ADDITIVE THAT EVENTUALLY NEEDS REPLACED
4. LUBRICATES WATER PUMP SEAL
IS AN ADDITIVE THAT EVENTUALLY NEEDS REPLACED
THERE ARE DIFFERENT KINDS OF COOLANT
• GREEN (CONVENTIONAL)– RECOMMENDED TO BE CHANGED
ONCE A YEAR
• PINK (DEX COOL)– RECOMMENDED TO BE CHANGED
EVERY 5 YEARS (SOME PROBLEMS)
• ORANGE
COMPONENTSLETS GET THESE IN OUR NOTES UNDER LIQUID COOLING
• WATER JACKETS– PASSAGES MADE (CAST) INTO CYLINDER
BLOCKS AND HEADS– SPACES WHERE COOLANT FLOWS
•CAUSES COOLANT TO FLOW•USUALLY DRIVEN BY BELT FROM CRANK•SHAFT SUPPORTED BY BEARNING•SEAL PREVENTS COOLANT LEAKAGE
WATER PUMP
WEEP HOLE TO PREVENT LEAKING COOLANT AWAY FROM BEARING
OVER TIGHTING BELT WILL CAUSE BEARING FAILURE
UNDER TIGHTING WILL CAUSE BELT SLIPAGEENGINE OVER HEAT WILL RESULTBELT FAILURE WILL RESULT
LETS REVIEW• AIR COOLING
• LIQUID COOLING– COOLANT
• PURPOSES OF ANTIFREEZE• HOW TO HANDLE
– WATER JACKETS– WATER PUMPS
HAVE LARGE SURFACE AREA FOR HEAT TRANSFER. FINS ON RADIATOR ADD SURFACE AREA FOR HEAT TRANSFER. COOLANTUSUALLY TRAVELS FROM TOP TO BOTTOM.
PRESSURE CAPS
SEALS COOLING SYSTEMTO ALLOW PRESSURE
TO FORM FROM EXPANDINGCOOLANT
PRESSURE RAISES BOILINGPOINT OF WATER
1 LB OF PRESSURE RAISESBOILING POINT 3 DEGRES F
PREVENTS A VACUUM FROMFORMING AS COOLANT
COOLS AFTER SHUT DOWN
PRESSURE CAP OPERATION
SEALING, COOLANT HEATING AND EXPANDINGCREATING PRESSURE
PRESSURE EXCEEDESSPRING, VALVE OPENSAIR AND COOLANT LEAVEOVERFLOW TUBE
AS COOLANT LOSSES TEMPERATUREIT CONTRACTS. A VACUUM IS PREVENTED
SO RADIATOR AND HOSES WON’T COLLAPSE.
ALLOWS COOLING SYSTEM TO REMAIN FULL AT ALLTIMES. PREVENTS CORROSION AND ALLOWS CHECKINGOF COOLANT LEVEL WITHOUT REMOVING CAP.
CAP FORRECOVERY
SYSTEM HAS TOHAVE TWO SEALS.
ENGINE UP TO TEMPERATURE
WAX PELLET EXPANDSPUSHING VALVE OPEN.
VALVE OPEN, COOLANTCAN FLOW TO RADIATOR
TO COOL.
THERMOSTAT NOTES
• CLOSED = COOLANT TRAPED IN ENGINE, GETS HOT
• OPEN = COOLANT CAN FLOW TO RADIATOR TO COOL
• ALLOWS JUST THE RIGHT AMOUNT TO FLOW TO KEEP EVEN TEMPERATURE
• MOST MODERN VEHICLES CALL FOR 195 F.
• USED TO BE AS LOW AS 140 F.• MORE HEAT = MORE POWER
AND GAS MILAGE (BTU’s)
• STUCK CLOSED– ENGINE OVERHEATS
• STUCK OPEN– LESS POWER– LESS EFFIENCY (MPG)– CONTAMINATED OIL– MORE EMISSIONS– HEATER BLOWING COLD
AIR
HEATER CORE• HOW WE HEAT PASSENGER
COMPARTMENT– CONTROLLING HEAT
• HEATER CONTROL VALVE
• BLEND DOOR
– LEAKS– LOSS OF HEAT
• THERMOSTAT STUCK OPEN
• PLUGGED
• LOW COOLANT LEVEL / NO FLOW
HOSES• TYPES
– PRE-FORMED– FLEX
• SPRINGS• WHEN TO CHANGE
– HARD– SOFT– BULGING– BEFORE THEY BREAK
• RECOMMENDED EVERY 6 YEARS
FANS• PURPOSE
– PROVIDE AIR FLOW THRU RADIATOR AT LOW SPEEDS. NOT NEEDED AT HIGH SPEEDS
• TYPES– SOLID– ENERGY CONSERVING
• FLEX
• CLUTCH
• ELECTRIC