Bài giảng môn Hệ thống Phanh

y khí Diagnosis Technician >> Brake >> Brake SystemPHÂN LOẠI @ Theo cơ cấu phanh: - Phanh trống (guốc) - Phanh đĩa - Phanh đai @ Theo trợ lực phanh: - Trợ lực bằng chân không - Trợ lực bằng thủy lực - Trợ lực bằng khí nén Ngoài ra, còn có: - Phanh bằng động cơ - Phanh khí xả Diagnosis Technician >> Brake >> Brake SystemYÊU CẦU - Lực phanh lớn và tác dụng nhanh (nhạy), có khả năng dừng xe gấp với thời gian và quãng đường phanh ngắn nhất - Hoạt động êm dịu, tính ổn định chuyển động của xe khi phanh cao - Lực phanh phân phối ở các bánh xe theo qui luật phân bố tải trọng - Lực tác dụng lên bàn đạp phanh nhẹ nhưng có khả năng tạo ra lực phanh lớn ở các cơ cấu phanh - Lực phanh ở các cơ cấu phanh phải tỉ lệ với lực tác dụng lên bàn đạp phanh - Thoát nhiệt tốt, có khả năng hoạt động liên tục trong khoảng thời gian dài - Dễ kiểm tra, sửa chữa Diagnosis Technician >> Brake >> Brake SystemHỆ THỐNG PHANH THỦY LỰC @ Các bộ phận chính: - Bàn đạp phanh - Bộ trợ lực phanh - Xy lanh chính - Đường ống dẫn động dầu - Các van phân phối và điều chỉnh lực phanh - Cơ cấu phanh (trống, đĩa) Diagnosis Technician >> Brake >> Brake SystemHỆ THỐNG PHANH THỦY LỰC @ Bố trí mạch dầu phanh: - Mạch thường (kiểu xe FR) - Mạch chéo (kiểu xe FF) - Diagnosis Technician >> Brake >> Brake SystemXY LANH CHÍNH @ Theo chức năng: - Phanh chính - Phanh đậu xe @ Theo dẫn động phanh: - Phanh cơ khí - Phanh thủy lực - Phanh khí nén - Phanh thủy khí Diagnosis Technician >> Brake >> Brake System Brake System (1/1) 6. Parking brake 5. Disc brake1. Brake pedal 2. Brake booster 3. Master cylinder 4. Proportioning valve (1) Disc brake (2) Disc brake Diagnosis Technician >> Brake >> Brake System Master Cylinder General & Construction (1/3) 1.General/2.Construction Minimum (5) Rubber piston cups (7) Fluid level sensor (6) Reservoir tank (1) No.1 piston (2) No.1 return spring (3) No.2 piston (4) No.2 return spring Diagnosis Technician >> Brake >> Brake System Master Cylinder General & Construction (2/3) 3. Principles Fulcrum Principle of the lever Wheel cylinder The principle of the lever is applied by the brake pedal as follows. A BF1  A = F2  B  F2 = F1  F1: Pedal force F2: Push rod output force A1: Distance from center of brake pedal to fulcrum B: Distance from push rod to fulcrum Operating force: Push rod b F2 A B F1 a Pascal’s law Master cylinder 5 cm2 10 cm2 2000 N 8 cm 40 c m 400 NSame pressure (2000 kPa)4000 N 2000 N 1000 N 10 cm2 20 cm2 b B A B a A B A a: Amount of movement of pedal edge b: Amount of movement of push rod Amount of movement: = a = b  b = a  Diagnosis Technician >> Brake >> Brake System Master Cylinder General & Construction (3/3) 4.Types of brake lines Front FR vehicle FF vehicle Front Diagnosis Technician >> Brake >> Brake System Master Cylinder Operation (1/4) 1.Normal operation No.2 return spring FF vehicle to front side No.1 return spring to Rear side No.2 piston Compensating port Inlet port No.1 piston No.1 piston cup Stopper bolt No.2 piston cup Diagnosis Technician >> Brake >> Brake System Master Cylinder Operation (2/4) Brake pedal depressed (1) to Front side to Rear side No.2 piston Compensating port Piston cup No.1 piston Brake pedal depressed (2) Diagnosis Technician >> Brake >> Brake System Master Cylinder Operation (3/4) Brake pedal released (1) to Front side to Rear side Inlet port Piston cup Compensating portOrifices Brake pedal released (2) Diagnosis Technician >> Brake >> Brake System Master Cylinder Operation (4/4) to Front side to Rear side No.1 piston Contact No.2 piston Diagnosis Technician >> Brake >> Brake System Master Cylinder Operation (4/4) to Front side to Rear side No.1 piston Piston contacts wall No.2 piston Diagnosis Technician >> Brake >> Brake System Brake Booster General & Construction (1/1) (12) Constant pressure chamber (5) Diaphragm (3) Booster piston (7) Valve body (8) Reaction disc 1.General/ 2.Construction (13) Check valveVacuum Brake master cylinder (10) Body seal (2) Push rod (4) Booster body (6) Diaphragm spring (11) Variable pressure chamber Air (1) Valve operating rod (9) Air cleaner (10) Body seal HINT: Tandem brake booster Diagnosis Technician >> Brake >> Brake System Brake Booster Operation (1/1) Booster piston Control valve Diaphragm spring Vacuum valve (opened)Piston 1.Brakes not applied Valve operating rod Variable pressure chamber Constant pressure chamber Air valve (closed) Variable pressure chamber Passage B Air valve return spring Air cleaner element Control valve Control valve spring Valve operating Constant pressure chamber Valve bodyPassage A Diagnosis Technician >> Brake >> Brake System Brake Booster Operation (1/1) Booster piston Control valve Piston 2.Brakes applied Valve operating rod Variable pressure chamber Constant pressure chamber Air valve (opened) Variable pressure chamber Control valve spring Air cleaner element Control valve Control valve spring Valve operating rod Constant pressure chamber Control valve Passage A Vacuum valve (closed) Passage BAir valve (closed) Air Passage B Booster push rod Diaphragm spring Diagnosis Technician >> Brake >> Brake System Brake Booster Operation (1/1) Booster piston Control valve Piston 3.Holding state Valve operating rod Variable pressure chamber Constant pressure chamber Variable pressure chamber Control valve spring Valve operating rod Constant pressure chamber Control valve Diaphragm spring Vacuum valve Air valve (closed) Stopped Diagnosis Technician >> Brake >> Brake System Brake Booster Operation (1/1) Booster piston Control valve Piston 4.Maximum boost Valve operating rod Variable pressure chamber Constant pressure chamber Variable pressure chamber Control valve spring Valve operating rod Constant pressure chamber Control valve Diaphragm spring Vacuum valve Air valve (opened) Booster push rod Air Diagnosis Technician >> Brake >> Brake System Brake Booster Operation (1/1) Booster piston Control valve Piston 5.Non-vacuum condition Valve operating rod Variable pressure chamber Constant pressure chamber Variable pressure chamber Valve body Valve operating rod Constant pressure chamber Control valve Diaphragm spring Vacuum valve Air valve Booster push rod Valve stopper key Reaction disc Diagnosis Technician >> Brake >> Brake System Brake Booster Reaction mechanism (1/1) Valve body Air valve 1.General/2.Operation Reaction disc 20 N (to Air valve) 80 N (to Valve body) Booster push rod 100 N 1cm2 (20N) 4cm2 (80N) Diagnosis Technician >> Brake >> Brake System Brake Booster Gap Adjustment of Push Rod (1/1) Choke applied SST Thickness gauge BRAKE BOOSTER ADJUSTMENT •Thickness Gauge(0.2mm or 0.008inch) and Special Service Tool(SST 09737- 00010)are required to check and adjust the push rod length. • See Repair Manual for details. Accessory tool SST STT 09737-00010 Diagnosis Technician >> Brake >> Brake System Brake Booster Function Check (1/1) Airtightness function cheek to Intake manifold Atmospheric pressure Atmospheric pressure Operating cheek to Intake manifold Atmospheric pressure Vacuum to Intake manifold Atmospheric pressure Vacuum tightness function cheek Vacuum Diagnosis Technician >> Brake >> Brake System Brake Booster Function Check (1/1) Airtightness function cheek to Intake manifold Atmospheric pressure Atmospheric pressure Operating cheek to Intake manifold Atmospheric pressure Vacuum to Intake manifold Atmospheric pressure Vacuum tightness function cheek Vacuum 1.Airtightness function check Diagnosis Technician >> Brake >> Brake System Brake Booster Function Check (1/1) Airtightness function cheek to Intake manifold Atmospheric pressure Atmospheric pressure Operating cheek to Intake manifold Atmospheric pressure Vacuum to Intake manifold Atmospheric pressure Vacuum tightness function cheek Vacuum 2.Operation check Diagnosis Technician >> Brake >> Brake System Brake Booster Function Check (1/1) Airtightness function cheek to Intake manifold Atmospheric pressure Atmospheric pressure Operating cheek to Intake manifold Atmospheric pressure Vacuum to Intake manifold Atmospheric pressure Vacuum tightness function cheek Vacuum 3.Load airtightness function check Diagnosis Technician >> Brake >> Brake System Proportioning Valve General & Construction (1/1) (a) Desired curve-line of braking force Rear wheel braking fore Contact with P valve 1.General/2.Construction Front wheel braking force (b) (4) Compression spring (5) Cylinder cup (2) Piston (1) Valve body (3) Valve seal Front Diagnosis Technician >> Brake >> Brake System Proportioning Valve Operation (1/1) from Master cylinder Cylinder cup Split point Master cylinder pressure Master cylinder hydraulic pressure Spring Master cylinder hydraulic pressure Force by the difference in the pressure reception surface area to Rear wheel cylinders R ea r w he el c yl in de r pr es su re Piston Diagnosis Technician >> Brake >> Brake System Proportioning Valve Operation (1/1) from Master cylinder 1. Operation up to the split point Cylinder cup Split point Master cylinder pressure Master cylinder hydraulic pressure Spring Spring force Force by the difference in the pressure reception surface area Master cylinder hydraulic pressure Force by the difference in the pressure reception surface area to Rear wheel cylinders R ea r w he el c yl in de r pr es su re Piston Diagnosis Technician >> Brake >> Brake System Proportioning Valve Operation (1/1) from Master cylinder 2.Operation of the split point Cylinder cup Split point Master cylinder pressure Master cylinder hydraulic pressure Spring Spring force Force by the difference in the pressure reception surface area Master cylinder hydraulic pressure Force by the difference in the pressure reception surface area to Rear wheel cylinders R ea r w he el c yl in de r pr es su re Piston in Contact Diagnosis Technician >> Brake >> Brake System Proportioning Valve Operation (1/1) from Master cylinder 3.Operation after the split point Cylinder cup Split point Master cylinder pressure Repeating Spring in Contact to Rear wheel cylinders R ea r w he el c yl in de r pr es su re Piston Piston Diagnosis Technician >> Brake >> Brake System Proportioning Valve Operation (1/1) from Master cylinder 4.Operation when the pedal is released Cylinder cup Spring to Rear wheel cylinders Piston Diagnosis Technician >> Brake >> Brake System Proportioning Valve Types of P Valve (1/2) Dual P.valve 1.Dual P Valve/ 2.Proportioning & Bypass Valve (P & BV) Master cylinder Spring Passage (opened) Air chamber P & BV Piston No.1Piston No.2 Spring Front Front Piston Cylinder cup Dual P valve P & Bypass valve Diagnosis Technician >> Brake >> Brake System Proportioning Valve Types of P Valve (2/2) Control the effectiveness 3. Load Sensing Proportioning Valve (LSPV) LSPV Out line Cylinder cup from Master cylinder Piston LSPV Valve seal Valve body Extends Load-sensing spring Cross section Split points Veh. fully loade d Vehic le unl oaded R ea r w he el c yl in de r h yd r. pr es su re Master cylinder (front wheel cylinder) hydr. pressure to Rear wheel cylinder Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (1/6) 1.Construction/ 2.Operation Before operation (4) Piston (1) Disc brake caliper During operation (5) Fluid (1) Disc brake caliper (3) Disc brake rotor(2) Disc brake pad Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (2/6) 3.Brake Adjustment Disc brake rotor Amount or return Piston seal changes shape as piston moves. Brakes applied Disc brake caliper Piston seal returns piston by amount of its deformation. Clearance Disc brake pad Amount of deformation Piston Brakes released Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (3/6) 4.Decrease in brake fluid Reservoir tank Brakes pad wear Master cylinder Disc brake pad Piston After pad wear Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (4/6) 5.Pad wear indicator Direction of disc brake rotor rotation Anti-squeal shimDisc brake pad Pad wear indicator Pad wear indicator Backing plate Before pad wear After pad wear Inner pad Pad wear indicator to ECU Clip Pad wear indicator Before pad wear After pad wear ECU ECU Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (5/6) 6.Types of disc brake caliper Disc brake caliper Torque plate Disc brake rotor Hydraulic pressure Pin Fixed caliper type Floating caliper type Inner pad Pin Torque plate Disc brake caliper Steering knuckle (Fixed) AD type Bolt Disc brake pads FS type Pin Pin Disc brake caliper Bolt PD type Torque plate Disc brake caliper Bolt Torque plate Diagnosis Technician >> Brake >> Brake System Foot Brake Disc Brake (6/6) 7.Types of disc brake rotor Ventilated type with Drum typeSolid type HINT: Fading Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (1/4) 1.Construction/ 2.Operation (1) Wheel cylinder (2) Brake shoe (3) Brake lining (4) Return spring (6) Piston (7) Piston cup (5) Brake drum Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (2/4) 3.Leading shoe and trailing shoe Self-energing function Wheel cylinder Direction of drum rotation Leading shoe Trailing shoe Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (3/4) 4.Types of the drum brake Fixed wheel cylinder Fixed anchor Fixed wheel cylinder Adjusting cylinder Fixed wheel cylinder Fixed wheel cylinder Two-Leading typeLeading-and-trailing type Duo-servo typeUni-servo type Fixed wheel cylinder Adjusting cylinder Forward Backward Leading shoe Trailing shoe Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (3/4) Fixed wheel cylinder Fixed anchor Fixed wheel cylinder Adjusting cylinder Fixed wheel cylinder Fixed wheel cylinder Two-Leading typeLeading-and-trailing type Duo-servo typeUni-servo type Fixed wheel cylinder Adjusting cylinder Forward Backward Leading shoe Trailing shoe Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (4/4) 5.Clearance Adjustment (2) Manual adjustment type(1) Auto adjustment type HINT: Brake Pedal Height Adjustment Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (4/4) Adjust lever Gap is larger Adjustor Brake shoe Drum Gap between shoe and drum is larger shoe lever Adjust lever Adjustor Adjust lever Adjustor The adjust lever turns the adjustor Diagnosis Technician >> Brake >> Brake System Foot Brake Drum Brake (4/4) Contract Expand Diagnosis Technician >> Brake >> Brake System Parking Brake Types of Parking Brake Lever (1/1) Release lever Lever type 1.Lever type/ 2.Stick type/ 3.Pedal type Stick type Pedal type Parking pedal Parking pedal Lock Release HINT: Parking Brake Lever Travel Adjustment Diagnosis Technician >> Brake >> Brake System Parking Brake Types of Parking Brake Body (1/1) Brake shoe Drum brake type Parking brake cable Piston Parking brake cable Brake shoe Shoe lever Shoe lever Disc brake pad Disc brake type Devoted parking brake type Center brake type Parking brake cable Shoe lever Brake shoe Disc brake pad Brake shoe Diagnosis Technician >> Brake >> Brake System Parking Brake Types of Parking Brake Body (1/1) Brake shoe Drum brake type Parking brake cable Piston Parking brake cable Brake shoe Shoe lever Shoe lever Disc brake pad Disc brake type Devoted parking brake type Center brake type Parking brake cable Shoe lever Brake shoe Disc brake pad Brake shoe 1.Foot brake sharing type Diagnosis Technician >> Brake >> Brake System Parking Brake Types of Parking Brake Body (1/1) Brake shoe Drum brake type Parking brake cable Piston Parking brake cable Brake shoe Shoe lever Shoe lever Disc brake pad Disc brake type Devoted parking brake type Center brake type Parking brake cable Shoe lever Brake shoe Disc brake pad Brake shoe 2.Devoted parking brake type Diagnosis Technician >> Brake >> Brake System Parking Brake Types of Parking Brake Body (1/1) Brake shoe Drum brake type Parking brake cable Piston Parking brake cable Brake shoe Shoe lever Shoe lever Disc brake pad Disc brake type Devoted parking brake type Center brake type Parking brake cable Shoe lever Brake shoe Disc brake pad Brake shoe 3.Center brake type Diagnosis Technician >> Brake >> Brake System Brake Booster Tandem Brake Booster (1/1) Intake manifold No.2 piston No.1 piston Air Variable pressure chamber Constant pressure chamber Diagnosis Technician >> Brake >> Brake System Brake Booster Fading (1/1) Temperature ( C) 100 200 300 400 500 C oe ffi ci en t f ric tio n ( ) 0.6 0.5 0.4 0.3 0.2 0.1 0 Diagnosis Technician >> Brake >> Brake System Foot Brake Brake Pedal Height Adjustment (1/1) Adjusting point Lock nut Push rod Pedal height Pedal freeplay Diagnosis Technician >> Brake >> Brake System Parking Brake Parking Brake Lever Travel Adjustment (1/1) Lock nutLever type Adjusting nut Adjusting nut Lock nut Stick type Adjusting nut Lock nut