The hydraulic system has four executive systems: slewing system, boom system, stick system and bucket system. In order to achieve the purpose of energy saving, the most typical structure of hybrid hydraulic excavator is to add a hydraulic motor generator system to the boom with large energy recovery.
The disadvantages of this structure are as follows:
1. The loss of inlet throttling, return throttling and bypass throttling is inevitable.
2. It is impossible to recover energy in slewing system, stick system and bucket system.
3. The addition of boom energy recovery system (hydraulic motor engine) will not only increase the cost, but also increase the energy conversion unit, which will reduce the energy saving effect.
4. Because there is no buffer circuit and oil supplement circuit, it is easy to produce cavitation and hydraulic shock.
