Disassembly and inspection method of main components of Hitachi excavator diesel engine --- cylinder head cover

Disassembly and inspection of main part of Hitachi excavator ZX200-3 excavator 4HK1 diesel engine

 cylinder head cover (1) Structure (1) The cylinder head cover assembly of 4HK1 diesel engine is shown in Figure 3-3-1. 

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   (2) The cylinder head cover assembly of 6HK1 diesel engine is shown in Figure 3-3-2. 

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 (2) Disassembly

  (1) Remove the cylinder head cover. See Figure 3-3-3 for the cylinder head cover of 4HK1 diesel engine, and Figure 3-3-4 for the cylinder head cover of 6HK1 diesel engine. 

 

  

 

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 (2) Remove the gasket.

  (3) Remove the injector harness connector. 

 (4) Remove the cylinder head cover. See Figure 3-3-5 for the cylinder head cover of 4HK1 diesel engine and Figure 3-3-6 for the cylinder head cover of 6HK1 diesel engine  

 

 

  

 (5) Remove the gasket. 

       (3) Installation 

 (1) Install the gasket on the lower cover. 

 (2) Install the cylinder head cover, tighten the cylinder head cover, tightening torque: 18N m (4HK1 diesel engine), 13N m (6HK1 diesel engine).  

(3) Install the fuel injector harness connector, and insert it completely until the lock claw is lifted. 

 (4) Install the gasket to the cylinder head cover. 

 (5) Install the cylinder head cover, see Figure 3-3-7 for the installation of the cylinder head cover for the 4HK1 diesel engine, and 3-3-8 for the installation of the cylinder head cover for the 6HK1 diesel engine. Tighten the bolts in the order shown in the figure, tightening torque: 18N.m (4HK1 diesel engine), 13N.m (6HK1 diesel engine). 

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Introduction to the Structural Features of SAA6D125E-3 and SAA6D107E-1 Diesel Engines for Komatsu Excavators (PC400-7 and PC200-8)

 (1) Overall structure diagram The structure of SAA6D125E-3 diesel engine is shown in Figure 2-3-1, and the structure of SAA6D107E-1 diesel engine is shown in Figure 2-3-2.

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    (1) SAA6D125E-3 diesel engine complies with strict emission regulations: US EPA standard (2001 regulation), European regulation 2002, Japanese construction equipment regulation 2003, it is a diesel engine with high performance, high efficiency, low fuel consumption and low noise, Improved exhaust color, improved acceleration. 

 (2) SAA6D125E-3 diesel engine and SAA6D107E-1 diesel engine are both in-line, 6-cylinder, water-cooled, direct-injection diesel engines. 

 (3) SAA6D125E-3 diesel engine and SAA6D107E-1 diesel engine adopt electronically controlled common rail fuel injection system, which injects high-pressure fuel at a pressure of 118MPa, which can provide the best injection control to match the speed and load, thereby improving Diesel engine emission performance, reducing fuel consumption and noise. 

 (4) The piston is made of high-quality steel, cast in a vibratory cooling furnace, and has the lowest thermal expansion in Komatsu tradition, which improves the reliability and life of the diesel engine. 

 (5) SAA6D125E-3 diesel engine and SAA6D107E-1 diesel engine adopt electronically controlled common rail fuel injection system and the design of optimal divergence characteristics at low temperature startup, which improves startup performance and reduces white smoke emission. 

 (6) The turbocharger used on the 125E-2 diesel engine is improved, so that the air supply cycle part can control the impact at the end of the compressor, so that the performance is optimal, the speed range from low speed to high speed is wider, and the fuel consumption is lower .

  (7) The thickness of the top surface of the cylinder block is increased, which can prevent deformation after long-term operation and make remanufacturing easier. In addition, by increasing the rigidity of the main reinforcement, the rigidity of the main body is improved, the deformation and vibration under load are reduced, and the generation of various noises is prevented. 

 (8) The size of the fuel supply pump of the electronically controlled common rail fuel injection system is 1/3 of the fuel supply pump of the ordinary in-line fuel injection system. In addition, the flange is used instead of the mounting seat, and it is tightly connected with the timing gearbox, thereby reducing noise.

  (9) The air filter is changed from ordinary end face seal to radial seal to prevent dust from entering and damaging parts. Additionally, a 5-segment display-type air filter clogging sensor provides accurate information on cleaning times.  

(10) The oil filter is a filter that combines high performance and high efficiency.

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(11) The fuel filter is a special fuel filter with high performance and high efficiency, which can filter out small particles of dirt and protect the electronically controlled common rail fuel injection system. 

 (12) If the electronic control unit judges that the diesel engine is working abnormally, it will issue a warning and the system will switch to the emergency escape mode. 

 (13) After starting the diesel engine at a very low temperature, if the diesel engine speed suddenly increases, the overload will apply excessive load to the bearing before the lubrication is sufficient, which will reduce the service life of the diesel engine, especially the overload will damage Non-locating bearings for turbochargers. In order to prevent this situation, a turbo protection system is installed to limit the diesel engine speed.

Introduction of Hitachi ZAXIS70/70LC Excavator Engine Control System

 
Introduction of  Hitachi ZAXIS70/70LC Excavator Engine Control System

A microcomputer built into the main controller (MC) monitors and controls all machine operations. The MC receives signals from the engine control knob and various other sensor switches. The MC then processes these signals and issues control signals to start the EC motor and various solenoid valves. The microcomputer control operation is as follows.
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1. Engine Control
The engine control system includes by combination: engine control knob control, E mode control, automatic idle speed control; optional ML (crane mode) engine speed limit control and engine learning control. The layout of the engine control system is shown in Figure 2-1.

2. Engine control knob control
Engine control knob control function: Control the engine speed according to the rotation angle of the engine control knob and reduce the engine speed by 100r/min when all joysticks are in the neutral position to reduce fuel consumption and noise. Operation: MC drives the governor lever according to the turning angle of the engine control knob to adjust the engine speed.
TIP: Even when the control knob is turned to the full speed position, the governor lever does not make contact with the full speed stop. With all joysticks in neutral (travel and nose attachment/swing sensors off)
After about 1 second, MC drives the EC engine to reduce the engine speed by 100r/min from the maximum speed.
The engine speed drops 100r/min from the maximum speed. Therefore, when the engine speed set by the engine control knob is already lower than the maximum speed of 100r/min, the engine speed remains unchanged. This engine speed deceleration control works regardless of whether the automatic idle speed control works. High and low idle speed control ranges are shown in Figure 2-2. The engine control knob controls are shown in Figure 2-3.

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The angle of rotation decreases proportionally.
The E-mode control diagram is shown in Figure 2-5.

4. Automatic idle speed control
engine control
knob position
Automatic idle speed control function: when all joysticks are in the neutral position
, reduce engine speed to reduce fuel consumption and noise levels.
Figure 2-4 Engine speed drops at a constant specified rate
Automatic idle speed control operation: about 3.5s after all joysticks return to the neutral position, MC drives the EC motor, as shown in Figure 2-6, to reduce the engine speed to the automatic idle speed. As long as the joystick is operated (travel and/or front attachment, swing pressure sensor on) the MC drives the EC motor to increase the engine speed to the original engine speed (set by the engine control knob). Conditions under which the automatic idle system does not work:
1) Joystick: When operating (travel, swing, or front attachment joystick when the pilot sensor is on).
2) Power mode switch: when E mode is converted into P mode or P mode is converted into E mode.
3) Engine Control Knob: When changing the engine speed.
The automatic idle speed control is shown in Figure 2-7.

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5. Idle acceleration control
Idling Acceleration Control Function: When the engine is running at a low speed, it prevents the engine from vibrating irregularly.
Idle speed acceleration control operation: as shown in Figure 2-8, when the engine is running at a speed between low idle speed and idle speed acceleration, when the travel or front-end accessory function is operated, MC drives the EC motor to make the engine speed idle speed acceleration control as shown in Figure 2 -9 shown.

6. Engine Learning Control
Engine Learn Function: Enter Governor Lever Stop in STOP
and FULL (full speed) side position as standard data to control the engine.
Engine learning operation: As shown in Figure 2-10, when the learning switch in the rear console is turned to the engine learning position, the EC motor is driven sequentially by signals from idle speed to full speed and to stop position. The EC sensor detects the position of the stoppers of the speed control lever on the FULL (full speed) and STOP (stop) sides and sends the stopper position signals to the MC, which stores these signals in its memory. Engine learning control is shown in Figure 2-11.
TIP: If repair work is done, be sure to perform an engine study. After performing the engine learning, use Dr.EX to check whether the engine learning has been carried out correctly.
When the battery is replaced, engine learning is not required.

7. Valve control
1. Travel motor swash plate angle control
Valve control function: select the walking speed in fast or slow mode.
2. Valve control operation
Slow mode: When the travel mode switch is in the SLOW (slow) position, MC will close the travel mode solenoid valve. The travel mode solenoid valve blocks the travel motor swash plate angle control oil pressure. Therefore, the travel motor swash plate angle increases, reducing the travel motor speed.
Fast mode: When the travel motor switch is set to the FAST (fast) position, MC will open the travel mode solenoid valve. The travel mode solenoid valve provides swash plate angle control oil pressure to the travel motor. Therefore, the angle of the travel motor swash plate is reduced, and the speed of the travel motor is increased.

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8. Walking alarm control
Walking alarm control works only when optional parts are installed. Walking alarm control function: the buzzer sounds when walking.
Walking alarm control operation: When performing a walking operation, the pressure sensor (walking) sends a signal to the MC. As soon as this signal is sent out, the MC outputs a signal to the walking alarm device to sound the buzzer.
Tips: After continuous walking for 13s or more, operating the buzzer release switch will disable the buzzer.
Walking alarm control is shown in Figure 2-13.
9. Slewing alarm control
The slewing alarm control works only when the option is installed.
Slewing alarm control function: During the slewing operation, the buzzer will sound while the indicator light is turning.
Swing alarm control operation: When performing a swing operation, the pressure sensor (swing) sends a signal to the MC. As soon as this signal is sent out, the MC outputs a signal to the slewing alarm device, sounds the buzzer and rotates the indicator light.
Note: Operating the buzzer release switch will disable the buzzer.
The rotation alarm control is shown in Figure 2-14.