Installation Method for 24V 7.5kW Stirling Engine Starter

I. Pre-installation Preparation

1. Tool and Material Preparation

• Mechanical Tools: Torque wrench (matched to the specifications of starter mounting bolts), socket set, locating pins, dial indicator (for coaxiality detection).

• Electrical Tools: Multimeter (for voltage/resistance measurement), crimping tool, insulating tape, cable fixing clips.

• Auxiliary Materials: Engine lubricating oil that meets specifications, high-temperature resistant gaskets, lock washers (spring washers or lock nuts), 24V DC power supply connecting cables (wire diameter not less than 16mm², suitable for the current demand of 7.5kW power).

2. Equipment Inspection and Confirmation

• Starter Side: Check that the stator and rotor are free from seizure, the solenoid switch operates flexibly, and the gear tooth surfaces are free from wear or missing teeth; use a multimeter to measure the resistance of the solenoid switch coil, which shall comply with the parameters in the manufacturer's technical manual (generally, the resistance of a 24V solenoid switch coil ranges from 3 to 5Ω).

• Engine Side: Clean oil stains and rust on the surface of the flywheel ring gear, check that the mounting surface of the flywheel housing is flat, and ensure that the threaded holes are not stripped.

• Electrical Matching: Confirm that the power supply is 24V DC with a rated current of not less than 400A (the rated operating current of a 7.5kW starter is approximately 300–350A) to avoid insufficient power supply leading to weak starting.

II. Mechanical Installation Steps

1. Positioning and Pre-installation

• Orient the drive gear end of the starter towards the flywheel ring gear of the engine, slowly fit it to the mounting surface of the flywheel housing, and insert 2–3 locating pins to fix the position of the starter, ensuring that the coaxiality deviation between the drive gear and the flywheel ring gear is ≤ 0.2mm (measure the end runout of the gear with a dial indicator).

• Place a high-temperature resistant gasket between the starter and the flywheel housing to prevent engine oil leakage.

2. Bolt Tightening

• Install the mounting bolts and put on lock washers, then pre-tighten the bolts in a diagonal cross sequence (the torque value is 50% of the final torque).

• Use a torque wrench to perform final tightening according to the torque specified by the manufacturer (generally 35–45N·m, subject to the starter manual), ensuring that the starter is free from looseness and deflection.

3. Meshing Clearance Inspection

• Manually push the drive gear of the starter to check the meshing clearance with the flywheel ring gear; the standard clearance is 0.3–0.8mm. If the clearance is too large or too small, it can be corrected by adjusting the thickness of the gasket (the gasket is installed between the starter mounting surface and the flywheel housing).

III. Electrical Connection Steps

1. Main Circuit Connection

• Take a copper core cable of 16mm² or above, connect one end to the main terminal of the starter (marked with “+” or “B+”), and the other end to the positive pole of the 24V power supply. Crimp a copper lug at the connection with a crimping tool and install an insulating sleeve.

• Tighten the main terminal with bolts, controlling the torque within 15–20N·m to prevent heating and ablation of the terminal caused by large current.

• Connect the grounding terminal of the starter housing to the engine body (or the negative pole of the power supply) with a grounding wire, whose diameter shall not be less than 10mm², ensuring that the grounding resistance is ≤ 0.1Ω.

2. Control Circuit Connection

• Take a 2.5mm² control cable, connect one end to the solenoid switch terminal of the starter (marked with “S” or “SW”), and the other end to the output terminal of the starting relay.

• Connect the input terminal of the starting relay to the ignition switch (or start button) to realize remote control of the starter. If remote control is not required, the solenoid switch terminal and the main terminal can be directly short-circuited for testing (the test duration shall not exceed 5s to avoid overheating of the starter).

3. Line Fixing

• Fix the main circuit cables and control circuit cables to the engine body with cable clips to prevent line wear and short circuit caused by engine vibration; the distance between the cables and high-temperature components of the engine (such as the exhaust pipe) shall not be less than 50mm.

IV. Post-installation Commissioning and Acceptance

1. No-load Test

• Disconnect the mechanical connection between the starter and the engine (or remove the spark plugs/injectors to make the engine unloaded), turn on the 24V power supply, and press the start button. The starter should run smoothly without abnormal noise or seizure, and the drive gear should extend and retract flexibly.

• Use a multimeter to measure the no-load current; the no-load current of a 24V 7.5kW starter is generally 80–120A. If the current is too high, it indicates a short circuit or seizure fault inside the starter.

2. Load Starting Test

• Restore the engine to the loaded state, turn on the power supply to start the engine; the starter should quickly drive the engine to run, with the starting time not exceeding 10s. If starting fails once, wait for 1–2min before restarting to prevent damage to the starter due to overheating.

• After starting, check that there is no oil leakage or abnormal vibration at the connection between the starter and the flywheel housing, and no heating phenomenon at the electrical terminals.

Key Precautions for Installation of 24V 7.5kW Stirling Engine Starter

I. Precautions for Mechanical Installation

Coaxiality and Clearance Control

1. The coaxiality deviation between the starter drive gear and the flywheel ring gear must be ≤ 0.2mm. Excessive deviation will cause abnormal gear meshing noise, intensified tooth surface wear and even tooth breakage. Calibration can be carried out by measuring the gear end runout with a dial indicator.

2. The meshing clearance shall be strictly controlled within 0.3–0.8mm. Excessively small clearance may lead to gear jamming and inability to rotate, while excessively large clearance will cause severe meshing impact. Adjustment shall be made by increasing or decreasing the thickness of gaskets on the mounting surface. Grinding the gear or ring gear for correction is prohibited.

Bolt Tightening Specifications

1. Lock washers (spring washers or lock nuts) must be installed on the mounting bolts. Tighten the bolts in two steps in a diagonal cross sequence: first pre-tighten to 50% of the final torque, then perform final tightening according to the torque specified by the manufacturer (35–45N·m, subject to the instruction manual).

2. Over-tightening the bolts is strictly prohibited, as it may cause thread stripping and starter housing cracking. Insufficient torque is also unacceptable, which will lead to starter loosening due to engine vibration and accelerated wear of starter brushes.

3. Do not strike the starter housing with metal tools during installation, to avoid deformation of the stator and rotor and damage to bearings, which may result in starter seizure during operation.

II. Precautions for Electrical Connection

Cable Specification Matching

1. The wire diameter of the main circuit cable shall not be less than 16mm² (copper core), and the wire diameter of the grounding cable shall not be less than 10mm². Undersized cables will cause heating under large current, leading to cable ablation, excessive voltage drop and weak starter cranking.

References：

GB/T 23642-2009 Technical Requirements for Electric Starting Devices of Internal Combustion Engines

QC/T 29064-1992 Technical Requirements for Starters for Automobiles

Manufacturer's Technical Manual (Taking the 24V 7.5kW Stirling Engine Starter as an Example)