As-T-T014 SQR372 Engine Mechanical

SQR 372 Engine structure characteristics

Engine technical parameterNo. Item Basic parameter

1

2

3

4

5

6

7

8

9

10

11

12

Type & model SQR372E three-cylinder water cooling, four-stroke, inline and head-laid double camshaft

Fuel system

Cylinder diameter

Piston stroke

Working volumeCompression ratio/compression

pressure

Combustion chamber typeIgnition sequence/ignition advance

angle

Fuel brand

Engine oil brand

Engine oil volume

Lubricating mode

Siemens VDO multi-point electric control gasoline injection system

72mm

66.5mm

0.812L

9.5：1/1.1~1.4MPa

Tent type

1-2-3/5±2°

No leaded petrol in high cleanliness not less than # (93)

SAE 10W/30 （grade SF）

Replacement of oil filter 2.9L

Combined type（pressure+splashing）

Engine technical parameter (Continuous)

No. Item Basic parameter

13

14

15

16

17

18

19

20

21

22

23

24

Overall size length*width*height

467*428*644mm³

Net mass

Intake valve opening angle

Intake valve closing angle

Exhaust valve opening angle

Exhaust valve closing angleEngine setting angle longitudinal

inclination

发动机安装角横倾

Idle speed/idle speed stability

Rated power

Max. torque

Min. fuel consumption

76Kg

19°before top dead center

59 °after bottom dead center

62°before bottom dead center

16°after top dead center

<=20°

<=15°

850±50r/min//<=30r/min

38KW/6000 r/min

70N•m/3500r/min

270g/KW•h

Engine setting angle transverse inclination

Main assembly structure characteristic and parameter

• Å Starter :• Permanent magnetism deceleration • In case of air temperature -25℃, engine shall start smoothly in 30S

without special measure to be taken, whilst start test shall be allowed to repeat three times; restart shall be conducted two minutes after first failure.

• Ç Generator: 14V65A unit type AC generator• É Spark plug: RC10YC4• Ñ Oil pump: Rotor type internal gear pump• Ö Oil filter: unit type cycle type• Ü Fuel pump: Motor pump inside fuel tank• áWater pump: Centrifugal type vane pump

I. Crank con-rod mechanism structure characteristics

• 1. Engine group• （1）cylinder body• Portal shaped— to ensure crankcase

rigidity• Main bearing seat width:

87.00~87.054• Main shaft hole diameter: Ø

46.025~46.041• Cylinder hole:Ø72.00~72.01 divided

into two groups, 0.005 in one group• Main shaft hole verticality:100：0.02• Cylinder center distance: 80• Upper plane plainness: 0.03• Tightening moment of main bearing

bolt: 70±3.5

（2）Cylinder cover Function: to seal cylinder head and form combustion chamber.Combustion chamber shape:tent shape (ridge shape)Material: Aluminum alloy die-casting moldingRequirement: lower plane plainness: 0.03Two fixed holes are equipped with cylinder cover. Valve guide assembly magnitude of interference: 0.040~0.066Liquid nitrogen frozen crushing; Valve guide seat magnitude of interference :0.121~0.087 frozen crushingTightening moment of cylinder cover bolt shall be in three cycles:30 ±2, 50 ±3 and 70±3.5N•m. Bolt hole degreasing shall be tightened from middle to both sides in a cross way.

（3）Cylinder washer and oil basin

Cylinder washer:Non-reusable part There is upper and lower side in installation, with a upward sign.Oil basin:Stamping, in adoption of body in taper shape to avoid engine oil shock; stress contact with cylinder body bottom, covered by gasket cement in stead of seal washer. Oil release plug shall adopt washer which can be magnetized.

2. Piston con-rod group（1）Piston:Piston shall be of planker type and aluminum alloy liquid forging molding, with fan steel mounted on pin seat.Flat head piston with four valve drop pits on the head; anode oxygenation; drop pit of frontward signØ3;Skirt section in bucket shape; tinning printing graphiteAssistant cylinder clearance:0.015~0.035，Clearance following grouping: 0.019~0.030Sign X on the head：71.975~71.981Sign S on the head: 71.981~71.987Weight grade: 190±3g

（2）Piston ring1st ring shall be bucket-shaped ring with upward sign SR in case of installation.Opening clearance: 0.25~0.40

2nd ring shall be cuniform ring:External lower undercutting R 0.2；

Upper leaning50‘Opening clearance: 0.35~0.50，Side clearance between two air intake rings:

0.03~0.06

Oil ring shall be combined ring which is plated with Cr0·08;Opening clearance: 0.2~0.7Side clearance: 0.012~0.17.

(3) piston pin and pinhole Semi-floating piston pinPiston pin seat hole: 1.2±0.1out of centerPiston pin seat hole shall be divided into different groups in case of piston grouping, with group sign printed on piston head:A represents 18.001-18.0035B represents 18.0035-18.006 Piston pin shall be divided into two groups:

18.005

18.003518.001

A/B

Weight of piston pin: 67g; Material: 15Cr(20Cr);Semi-floating: Small end of connecting rod heated to 150C° in installation

（4）Con-rod`

Material: 40Cr（35CrMn）

Small end hole: Ø18

Big end hole: Ø40

Bearing thickness: 1.5-0、006

Bearing material: AlSn12Si2.5Pb1.7

Con-rod length: 117.5±0.035

Weight of con-rod: 365g—383g

Divided into six groups: 3g/per group

(1.2——6) side sign of light-heavy

Interference cooperation between con-rod bolt and rod body;

Connecting rod bolt torque: 40±2N·m

-0.026-0.044

+0.041+0.025

Diagram 4

Brand

Piston forward sign

Con-rod cover heave

Piston con-bar group Assembly sign

Considerations in assembly:

heave“con-rod cover”, forward sign on con-rod (CAC brand) and forward sign on piston head(dot)shall be at the same direction (forward), with piston con-rod assembly formed following installation. Piston and piston pin shall not be grouped temporarily.

Diagram 4

Brand

Piston forward sign

Con-rod cover heave

Con-rod weight group。

Con-rod grouping as per weight:

Weight of con-rod assembly (not including bush) shall be 374±9g, whilst con-rod total weight is divided into six groups without weight removal, with weight difference of each group 3g; weight of loop rod and con-rod on same set shall be in the same weight group, with group

number group 1-6 printed on side of con-rod.

Weight grouping:

383g380g377g

374g371g368g365g

Installation of piston con-rod。

Piston pin

In case of con-rod assembly installation:Choose con-rod in one group. SQR372 engine con-rod shall be in six groups, with weight difference between each group 3g; con-rod small end hole dimension, bearing hole dimension shall not be grouped; whilst con-rod small end hole and piston pin hole shall be applied with interference cooperation with magnitude of interference 0.022-0.043mm. Con-rod small end and piston pin shall be semi-floating type.

Piston

Con-rod

3 Crankshaft flywheel group 。

（1）Crankshaft: full supporting; material: 49MnVsSi3

QT800-2（for later use）Ignition sequence: 1-2-3Crank inclination: 240°Crank radius: R=S/2=33.25Main shaft neck: 42Main shaft bearing:1.5Con-rod shaft neck: 37Con-rod bearing: 1.5

（AlSn12Si2.5Pb1.7）

Lengthwise thrust plate: on 3rd bearing; Lengthwise play:0.089~0.211Joint with oil pump:milled Joint with timing belt pulley: timing signJoint with flywheel: six bolt opening pinsFront&rear oil seal: support by shelf with oil return groove.

00.016

00.016

00.006

00.006

（2）Flywheel 。ÅÇÉÑÖÜáàâä

Function: Å Store energy of expansion strokeÇ Let piston go through dead pointÉ Power outputÑ Start engineÖ Determine ignition timeÜMeasure engine rotation speedRequirement: ÅMoment inertiaÇ Static balanceÉ Dynastic balance and uniqueness following crankshaft installationÑ Bounce on the surface

Crankshaft installationMain bearing:Upper bearing shall have fuel hole and fuel groove, whereas lower bearing has no fuel hole and fuel groove; clean bearing backMain shaft: There shall be number and forward arrowhead directional sign on main shaft cover;Thrust plate:Installed on 3rd bearing, with fuel groove side facing crank.Main shaft bolt:Tighten with tightening moment in two times: 70See right diagram for tightening sequence

±3·5N·m

Diagram 5

Rear Front

II. Air distribution mechanism

Function and constitution:Function:Turn on and turn off valve on time as per engine working cycle.Requirement:

Firstly, punctuality;Secondly, unification and evenness;

Constitution:Valve group: valve, oil seal, valve spring, valve seat and locking block;Valve drive group: timing pulley and timing belt, exhaust & intake camshaft and driving &driven gear, tappet pillar and adjusting washer.

Diagram 23

1. Valve group

（1）Valve: Material: 4Cr9Si2Valve rod: Ø5

/O /0.020.02

Valve cone angle: 45°30'Valve length: intake –76.53

exhaust –76.89Valve pipe and valve seat: immerse in liquid nitrogen for ten minutes and then press it in as required.

-0、03

-0、048

Diagram 12

Adjusting washer

ÅAdjusting washerÇValve tappet pillarÉValve lockerÑValve spring upper seatÖValve springÜValve oil sealáValve spring lower seatàValve

（2）Valve spring （4）Valve adjusting washer:Washer material: 20CrMoHeat treatment: carbonization

0.3~0.5Phosphorizing treatment

//0.0080.006

Thickness: 2.28~2.80Each 0.02 in one group

（Thickness typed by laser, choose thickened adjusting washer as per valve clearance, side with character upward）

Valve clearance: intake: 0.18±0.05exhaust: 0.25 ±0.05

Steel wire diameter: Ø3.2Spring internal diameter: Ø16.2Verticality: 1.2Free length: 37Closing valve: In case of compression force110±8·8N·m

spring length: 32.5Opening valve: In case of compression force 350 ±25N·m

spring length: max 23

（3）Valve tappet pillarmaterial: 20CrMo

Ø28-0.20

-0.33

/O/0.006 0.025

2. Valve transmission group （1） Crankshaft timing pulley

Timing sign diagram 21

Turn crankshaft to position of 1st

cylinder top dead center, with timing sign on crankshaft timing gear aiming at that on oil pump housing as shown in left diagram.

（2）Camshaft timing pulley

。

Material: powder metallurgy

Teeth number: 44

Key groove: leveling tooth root

Installation: exhaust camshaft

Notice: in case of timing pulley installation, no spark plug shall be installed; firstly ensure top dead center sign of camshaft timing gear aimed at sign on head of cylinder as shown in right diagram.

Diagram 20

Timing sign

（3）Exhaust camshaft

Material: Quench cast iron

Supporting: three bearings

Lubricating: pressure feed lubricating

Lift: 7.1(exhaust)

Camshaft timing pulley dowel pin

Locking bolt

Hexagon inter bolt

Joint flange

Exhaust camshaft gearDiagram 16

Hexagon shaft neck

Exhaust camshaft assy.

Exhaust camshaftgear sign position

Exhaust timingdowel pinhole position

Diagram 15

（4）Exhaust camshaft gear as well as its installation

Exhaust camshaft gear:

Timing gear dowel pin

Installation of exhaust camshaft gear:

Y The side with pit sign Ø5 shall face backward;

Y Cover shaft neck with dowel pin;

Y Align key groove and use four blots to joint flange ;

Y Inclination between pin and key groove 10·5°

Y Lock 24 lock nut with locking moment100±5N·m

Intake camshaft

Material: Quench cast iron

48 dents of main and secondary gear

Lift: 7.25(intake)

diagram 14

Intake camshaft main gear assy.

Intake camshaft secondary gear.

Drive ring

Intake camshaft assy.

Intake camshaftbaffle ring

Saddle elastic washer

Intake camshaft gearKey groove relative fixed pin position:

Signal gear of camshaft position sensor shall be installed on intake camshaft integrity casting, in a inclination36°±3° with 1st

cam.

Prior to amendment: Prior to amendment:

Drive ring fixed pin

Drive ring fixed pin

Exhaust & air intake camshaft timing drive gear installation sign

See following diagram for installation sign

Air intake camshaft gear shall be main gear and secondary gearIn case of installation:Rotate secondary gear to open tension spring ring, whilst mesh shall furnished in alignment of main and secondary tooth

Timing sign

III. SQR372 cooling systemConstitution and circulating water way

Overflow tank

Water pump

Warm wind

Thermostat

Radiator

Engine

Function of cooling system 。

1. Function: In engine expansion stroke, spread heat of heating part in high-temperature produced by fuel burning into air, so as to ensure engine in a temperature range of normal working (85~115ºC).Principle: By medium cycle flow, carry away part heat efficiently and conduct heat interchange with air.2. Type:Centrifugal pump, compulsive circulating water-cooling type. 3. Water way:Small cycle:Water pump – water pipe – water jacket – thermostat – water pump;Large cycle:Water pump – water pipe – water jacket – thermostat – radiator – water pump4. Fan: double temperature switch, ECU control and two-speed single electrical fan, with low speed ON at 94ºC and OFF at 91 ºC；high speed ON ay 105ºC, and switch to low speed at 101ºC. Cooling fan shall open automatically in case of turn-on A/C to cool condenser with wind.

Right usage and maintenance of cooling system

• 5. Coolant:• 50% glycol + 50% soft water• Fluid volume • Exhaust • Replacement and cleaning• 6. Radiator:• Type and material• Secondary overflow tank

(expansion tank)

• 7. Thermostat• Function• Mechanism • Installation • Trouble • 8. System • Pressure adjusting cover• Air release plug

• Cooling system trouble phenomenon and non-cooling system cause

• Trouble phenomenon• Besides temperature display, there is

other phenomenon. • 1. Engine knocking;• 2. Too high exhaust temperature with

red exhaust pipe；• 3. Engine inability with distinct power

decaying• Non-cooling system cause• 1. Car drives along wind blowing

direction for a long time;• 2. Gear haul, running at low gear for a

long time; • 3. Insufficient tire air pressure;• 4. Clutch slippage; • 5. Mixed gas too thin;• 6. Earlier/later ignition time;

……

• Cooling efficiency analysis• I. Medium selection• Common and inexpensive liquid in

high density and high fluidity – water and alcohol

• II. Pressurization – pump • Improve medium flow rate and carry

heat away

• III. Improve air flow rate and carry away heat from radiator

• Employ fan

• IV. Increase radiator area• Add pipe and vane on radiator

• V. Enlarge temperature difference between medium

• Enlarge temperature difference between coolant and air 115ºC；whilst pressurizing on cooling system

IV SQR372 lubricating system1. Function:

Lubricating, cooling, cleaning, anti-erosion, seal and buffering

2. Component:

Centralized filter assembly, oil pump, safety valve, pressure limiting valve, secondary main oil way, oil filter, main oil way, oil pressure switch, crankshaft oil way, vertical oil way, pressure limiting hole, camshaft oil way, oil-air separator and crankcase ventilation device.

3. Oil:

Oil capacity(L)

2.9（new oil filter）

Oil brand

SAE 10W/30（grade SF）

Lubricating oil way diagram Lubricating method diagram

Intake& exhaust camshaft oil wayOil-air separator

Crankcase ventilationCylinder body limit hole

Oil pressure switch

Safety valve

Oil pump

Centralized filter assembly

Filter

Oil basin

Oil vapor condenser

Main oil way

Lean oil way

Oil release plug

Subsidiary oil way

Vertical oil way

Lubricating mode & main parts

4. Lubricating mode:

Pressure feed lubricating+splash lubricating = combined type lubricating

Pressure feed lubricating position:

Shaft neck with large bearing;

Splash lubricating position:

Position which cannot be lubricated by pressure feed lubricating, shall adopt oil splash at pressure lubricating end.

5. Main part:

1) Internal gear pump:

Stable pressure, low noise; long life span

External gear pump

Internal gear pump

n

Pa

2) Oil filter:Full flow type, unit replacement;with replacement time as per Instruction

Main part of lubricating system

3) Safety valve:Installed on oil pump, to protect oil pump and limit pump output pressure and pressure on secondary oil way.4) Bypass valve:Ensure continuous oil supply in lubricating system, installed in filter.5) Pressure switch:Oil pressure warning switch, with warning lamp ON in case of pressure lower than 80KPa at engine idle speed; installed on vertical oil way.6) Pressure limiting holeLimit oil pressure of air distribution mechanism; press stamping into vertical oil way on cylinder body.

7) Central hole on intake and exhaust camshaft, a longitudinal oil way of air distribution mechanism; sealed by press-in friction ball. Transverse oil way shall be camshaft cap oil groove.

8) Oil basin:

Stamping, pyramidal groove and sealed by glue.

9) Oil draining screw plug:

Magnetic seal washer

Lubricating system trouble diagnosis and analysis• I. Requirement on lubricating system• 1. Necessary oil volume, oil quality and

viscosity (adherence) ；• 2. Any and all friction surfaces shall be

lubricated; more attention shall be paid to friction secondary surface which is difficult to lubricate (cylinder wall, valve lever and cam) ；

• 3. Surface with large bearing (axial diameter) shall transport lubricating oil by some pressure.

• II. Main trouble diagnosis and analysis of lubricating system

• 1. Too low engine pressure• Trouble phenomenon:• Warning of oil alarm: warning by sound and

light synchronously;• Trouble cause: (oil pressure falling suddenly):• Insufficient oil volume, with sudden oil

leakage;• Oil pump out of work;• Centralized filter assy. Drop-off;• Inefficiency of each valve, and oil discharge;

• Diagnosis method: notice: do not start engine in a hurry .

• Inspect oil volume;• Inspect each valve;• Inspect pressure sensor;• Inspect gauge;• Inspect belt;• Inspect filter assy. and pump, etc.• 2. Too high oil pressure• Trouble phenomenon:• Several oil leakages on engine;• Warning of main oil way high-pressure

valve• Trouble cause:• Inefficient oil pump safety valve (blocked);• Inefficiency of main oil way safety valve

(blocked);• Oil blockage: too small a bearing clearance; • Low oil temperature, improper brand and

thicker viscosity• Diagnosis method:• Inspection aimed at the “cause”

Lubricating system trouble diagnosis and analysis (III)• 3. Diagnosis and analysis of lubricating oil deterioration• Deterioration phenomenon:• Aging— observe oil drip, whilst normal one shall be translucent, with dark center

and translucent around as semi-aging, and all dark as aging. • Acidification—acidification shall be discovered by observing cauterization of shaft

bearing and piston in disassembly inspection, whilst test paper method shall be a reliable method to inspect acidification. Generally in case of engine oil aging in a degree to be replaced, acidification shall not be achieved.

• Emulsification— observe oil drip; in case of oil water emulsion state, the oil shall be mixed with some water.

• Dilution—Determined by deterioration or viscosity inspection• Deterioration cause:• Oil in use for a long time;• Crankcase ventilation failure;• Serous down flow of exhaust gas and mixed gas;• Inferior engine oil or fuel in use;• Inner leakage of cylinder body• Diagnosis method:• Regular maintenance and careful examination

Aging Semi-aging Translucent