GB/T 5770-2020 in English

Analysis of the core content of the standard

Detailed explanation of key technical requirements

3.4 Oil supply pre-stroke control

The pre-stroke limit deviation of the reference cylinder needs to be detected by a special measuring device. For the hydraulic timing correction plunger, special attention should be paid: The pull rod must be in the maximum stroke position to ensure that the plunger sleeve is completely separated from the oil return hole and the top clearance groove.

3.8 Oil supply characteristics

Newly added speed requirements for the speed regulator to take effect. The average oil supply deviation rate of each cylinder under rated conditions is ≤±3%. The calculation formula is: γ=(Q-Qc)/Qc×100%, where Qc is the designed oil supply.

3.12 Maximum pump end pressure

The original recommended value of 100/120MPa corresponding to National II/III emissions has been cancelled and changed to a value that must not exceed the design allowable value of the injection pump, which is more in line with actual engineering needs.

Test method upgrade

• 4.1.5: Added pressure tester accuracy requirements (0-200MPa, error ≤±3%)
• 4.2.7/4.2.8: Added injection start point and pump end pressure measurement items
• Sealing test: High pressure chamber detection pressure increased to 0.5MPa (O-ring seal is 0.4MPa)

Implementation suggestions

1. Manufacturers should update the test bench pressure sensor range to 200MPa
2. For hydraulic timing correction plunger products, the JB/T12043 standard must be implemented simultaneously
3. It is recommended to establish a pump end pressure design value database to replace the corresponding value of the original emission standard