Excavator Main Control Valve with Level-Mode Pump Confluence
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Solution Overview
Problem
The hydraulic circuit of small hydraulic excavators experiences energy loss and reduced efficiency due to overflow from the pump with lower rated pressure during excavation and slow levelling speeds due to insufficient flow from this pump during levelling, leading to inefficient energy use and movement speeds.
Innovation Solution
A main control valve with a level-mode oil supply circuit that allows pumps P1 and P2 to supply oil confluently to the arm cylinder, and P1 and P2 to supply oil for arm and bucket movements after throttling, while P3 supplies oil preferentially to the arm during levelling, optimizing oil flow and pressure distribution to prevent overflow and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pump P3 with lower rated pressure is used in the hydraulic circuit, then the system can handle low-pressure operations, but the pump overflows in advance during hard soil excavation causing energy loss
Solution Approach 1:
The patent implements a dynamically switchable hydraulic circuit configuration that changes oil supply routes based on working conditions. During excavation, pumps P1 and P2 supply oil to the arm and bucket, while during levelling, pump P3 is preferentially connected to supply oil to the arm. This dynamic reconfiguration prevents pump P3 from overflowing during high-pressure excavation while utilizing its flow capacity during low-pressure levelling operations.
Solution Approach 2:
The patent changes the operational parameters of the hydraulic system by implementing different oil supply modes: in excavation mode, pumps P1 and P2 operate at high pressure with controlled flow distribution, while in levelling mode, pump P3 operates at lower pressure with preferential flow allocation to the arm cylinder. This parameter switching optimizes energy efficiency across different working conditions.
2Loss of energy
If pump P3 with smaller rated flow is used, then the system can operate at lower pressures, but the arm in and out speed is relatively slow during levelling
Solution Approach 1:
The patent implements a dynamically switchable hydraulic circuit configuration that changes oil supply routes based on working conditions. During levelling, the circuit is reconfigured to supply oil from pumps P1, P2, and P3 confluently to the arm cylinder, maximizing available flow and achieving rapid arm movement. During excavation, the circuit switches to use only pumps P1 and P2 for high-pressure operations, preventing pump P3 from overflowing and wasting energy.
Solution Approach 2:
The patent segments the hydraulic circuit into different supply paths: a high-pressure path using pumps P1 and P2 for excavation, and a high-flow path that can utilize all three pumps (P1, P2, and P3) for levelling operations. This segmentation allows optimal performance in each working mode without compromise.
3Adaptability or versatility
If bypass diffluence control is applied during single-movement of arm, then oil flow can be distributed to multiple actuators, but great bypass diffluence energy loss occurs
Solution Approach 1:
The patent implements dynamic flow distribution control where the oil supply route is selectively activated based on the required operation. During single-movement of the arm, the circuit is configured to supply oil directly from the selected pump to the arm cylinder without bypassing through other actuators, eliminating unnecessary energy loss. During composite movements, the circuit dynamically switches to provide confluence oil supply to multiple actuators. This dynamic control eliminates the energy waste associated with constant bypass diffluence control.
4Power
If overflow occurs during composite-movements and oil returns to the oil tank directly, then the system can handle high loads, but great overflow loss and waste occur
Solution Approach 1:
The patent changes the operational parameters by implementing pressure-based flow control during composite-movements. Instead of allowing direct overflow to the tank, the system maintains pressure control and directs overflow flow through productive paths to other actuators that still require hydraulic power. This transforms waste overflow into useful work, maintaining system pressure and power utilization during high-load composite operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces energy loss, accelerates excavation and levelling speeds, and ensures efficient energy use by preventing overflow and optimizing oil flow distribution, resulting in a highly-efficient and energy-saving main control valve.
Implementation Method 1
a main control valve for a hydraulic excavator, which comprises: an oil inlet unit through which hydraulic oil supplied from a hydraulic power source is introduced; a first arm unit supplied with the hydraulic oil from the oil inlet unit to drive an arm cylinder; a second boom and hammer unit supplied with the hydraulic oil from the oil inlet unit to drive a boom cylinder and a hammer cylinder; a bucket unit supplied with the hydraulic oil from the oil inlet unit to drive a bucket cylinder; a level-mode selecting unit supplied with the hydraulic oil from the oil inlet unit to select a level-mode
Implementation Method 2
the level-mode selecting valve is a hydraulically-controlled two-position three-way valve... the pump P3 supplies oil to the arm preferentially through the level-mode selecting valve
Implementation Method 3
after throttling, the pump P1 and the pump P2 supply oil for bucket in and out, and the pump P1 and the pump P2 supply oil for the boom... supplies oil to the bucket after throttling via a throttle hole
Data Source
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AI summary
A main control valve for a hydraulic excavator and a hydraulic excavator having the same. The hydraulic excavator main control valve comprises: a straight travel valve unit (1), a rotary unit (2), a dozer blade unit (3), a boom 2\hammer unit (5), an arm 1 unit (6), a travel left unit (7), an oil inlet unit, a travel right unit (8), a boom 1 unit (9), a bucket unit (10), an arm 2 unit (11), and an oil return passage (T2). The main control valve for hydraulic excavator is oil supplied by three pumps (P1, P2, P3) comprising a first pump (P1), a second pump (P2), and a third pump (P3). The first pump (P1) and the second pump (P2) are two variable pumps having the same displacement, and the third pump is standalone. The three pumps (P1, P2, P3) are under total power control, and the rated pressure of the third pump (P3) is less than the rated pressure of the first pump (P1) and that of the second pump (P2). The main control valve for hydraulic excavator further comprises a level-mode oil supply circuit, though which the first pump (P1), the second pump (P2) and third pump (P3) supply oil confluently to the arm cylinder of the hydraulic excavator. The main control valve for hydraulic excavator makes single-movements more rapid, and oil flow distribution is done appropriately during composite-movements. The valve also has the advantages of high work efficiency when in a level position and energy-saving when excavating.