Engine Lubrication Ben Rossiter

Lubrication System Introduction

Friction We talked earlier of frictional losses, these were ______________________________ The crankshaft bearings, both ‘big end’ and ‘main’ undergo high amounts of friction. “In order to prevent metal to metal contact occurring, a thin film of oil is present, with the friction loss coming from the metal parts running very close together, with often differing speeds, overcoming the viscosity of the oil.” Around the cylinder walls and piston rings

Oil Functions

Friction Losses Lubrication is vital to the long life of an engine. We discussed earlier how Formula 1 engines have high friction losses, owing to the high engines speeds used. Any speed over 6000rpm will quickly see sharp rises in the amount of friction losses and this is why most engines do not operate much beyond this.

Lubrication System – Wet Sump Oil is held in the sump. Drawn into engine through the pickup. Forced round by a pump. Protected by a pressure relief valve. Particulates removed by a filter. Carried around in galleries. Next > 6

Oil Sump

Use of Oil Acts as barrier to reduce friction and wear. Usually refined from petroleum or crude oil. Oil film For rotating bearing, shaft diameter is less than the bearing inner diameter. Crankshaft journal Next > 8

Oiling Methods Pressure-fed systems feed upper parts of engine. Splash and drip-feed feeds down to the lower parts. Next > 9

Pressure System

Splash Lubrication

Oil Pump

Rotary Oil Pump Inner rotor driven by pump shaft. Inner rotor drives outer rotor. Oil is forced from input, to output. May be shaft, gear or chain driven. Next > 13

Crankshaft-Driven Pump Drive splines on crankshaft. Main seal. Inner gear (rotor) driven by crankshaft. Outer gear (rotor) driven by inner gear. Pump housing at front of engine. Pump insert holds drive within housing. Next > 14

Gear Pump Pump shaft drives one gear. Other gear turned. Low pressure at input. High pressure at output. Next > 15

Oil Filter

Oil Filter Spin-on oil filter with O-ring seal. Centre outlet tube. Input feed holes. Paper elements trap impurities. Keeps impurities out of the engine. Next > 17

Oil Filter Housing Bolts to cylinder block. Oil pressure switch. May have oil cooler adapter. Fed by oil cooler hoses. Oil filter. Heat shield. Next > 18

Pressure Relief Valve Found between the pump and the filter, The pressure relief valve is used to prevent damage to an engine due to too much oil pressure.

Pressure Relief Valve

Oil Coolers

Oil Cooler May be used to lower oil temperature. Heat exchanger similar to radiator. Hoses/pipes are usually connected to adapter on oil filter. Often used for heavy duty applications. Next > 22

Galleries – Wet Sump Carry oil to all parts of engine. Lubricates valve gear, crank and camshaft. Cylinder bores. To and from oil filter. From pickup to pump. Next > 23

Dry Sump Q. How does this system differ from a wet sump? A. It uses an additional pump (Scavenge pump) as well as a remote oil tank. Q. When would a Dry sump system be used? A. It is used in situations when a wet sump cannot cope with the oil supply, in unusual or extreme conditions; Heavy acceleration (racing cars), Off road driving, steep hills and uneven surfaces

Lubrication Terminology 1. Full-flow – a) Full flow filter A filter that, under specified conditions, filters all influent flow. b) Full-flow filtration A system of filtration in which the total flow of a circulating fluid system passes through a filter 2. Hydrodynamic - A system of lubrication in which the shape and relative motion of the sliding surfaces causes the formation of a fluid film having sufficient pressure to separate the surfaces.

Lubrication Terminology cont. 3. Boundary - Form of lubrication between two rubbing surfaces without development of a full-fluid lubricating film. - Boundary lubrication can be made more effective by including additives in the lubricating oil that provide a stronger oil film, thus preventing excessive friction and possible scoring. - There are varying degrees of boundary lubrication, depending on the severity of service.

Lubrication Terminology cont. 4. Viscosity - Measurement of a fluid's resistance to flow.

Lubrication Terminology cont. 5. Multi-grade - An oil meeting the requirements of more than one SAE viscosity grade classification, and may therefore be suitable for use over a wider temperature range than a single-grade oil.

Lubrication Terminology cont. 6. Synthetic oil – A lubricant produced by chemical synthesis rather than by extraction or refinement of petroleum to produce a compound with planned and predictable properties. 7. Viscosity Index – A commonly used measure of a fluid's change of viscosity with temperature. The higher the viscosity index, the smaller the relative change in viscosity with temperature.

Operational Requirements Operating Temps The average lubrication system temperature is 60c, compared to the average cooling system temperature of 90c. One of the main factors of oil deterioration is temperature fluctuation, this causes the beneficial properties and characteristics of the oil to be broken down and eventually lost. This sees a need for oil coolers on high performance cars

Operational Requirements Pressures At idle oil pressure should be around 0.7 bar Maximum oil pressure is 4 bar Lube grades (See additional handouts)

Oil Additives

Additives Viscosity index improvers - These reduce viscosity change with temperature, permit reduced fuel consumption, maintain low oil consumption and allow easy cold starting. Detergents dispersants - Keep sludge, carbon and other deposit forming material suspended in the oil for removal in the oil whit drains. Alkaline Compounds - Neutralize acids, prevents corrosion from acid attack. Anti-wear, Friction modifiers - Form protective films on engine parts, reduce wear, prevent galling and seizing, reduce fuel consumption

Additives continued Oxidation inhibitors - Prevent or control oxidation of oil, formation of varnish, sludge and corrosive organic compounds, limit viscosity increase that occurs as oil mileage increase. Rust Inhibitors - Prevent rust on metal surfaces by forming protective surface films or by neutralizing acids Pour point depressants - Lower ‘freezing’ point of oil, assuring free flow at low temperatures. Antifoam agents - Reduced foam in the crankcase.

Q. At what engine oil temperature should the emissions test be done at? The temperature is checked with a probe, placed where the dip stick is normally situated. The test is done at 60c.

Q. Explain Hydrodynamic Lubrication This form of lubrication relies on the natural movement of the oil between bearing surfaces to form a wedge, this separates them when they are moving, i.e.

Q. Explain Boundary lubrication This form of lubrication relies on the ability of the oil to cling onto and coat the surface of moving parts to avoid metal to metal contact, i.e.