Hydraulic Drive Device Flow Restriction for Excavator Operability
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Solution Overview
Problem
In hydraulic excavator operations, combined arm-crowd and bucket operations often result in lower load pressure on the arm compared to the bucket, leading to reduced operability and working efficiency due to insufficient pressure oil supply to the bucket cylinder.
Innovation Solution
A hydraulic drive device with a flow rate restriction device that controls the supply of pressure oil to the second arm directional control valve during combined operations, using a variable throttle and pilot pressure guidance to prioritize oil supply to the bucket directional control valve, and an electromagnetic switching valve to adjust flow based on operational demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pressure oil is supplied to both arm cylinder and bucket cylinder during combined operation, then both components can operate simultaneously, but the bucket cylinder receives insufficient pressure oil when load pressure on arm is lower than on bucket
Solution Approach 1:
The patent applies local quality by creating different flow rate conditions for different directional control valves. The flow rate restriction device selectively restricts pressure oil flow to the second arm directional control valve while allowing adequate flow to the bucket directional control valve. This localized differentiation ensures that the bucket cylinder receives sufficient pressure oil during combined operations when arm load pressure is lower than bucket load pressure, thereby improving operability without compromising pressure supply to the bucket.
2Quantity of substance
If flow rate to second arm directional control valve is not restricted, then arm operation is smooth, but pressure oil is diverted from bucket directional control valve during combined operations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the flow rate parameter to the second arm directional control valve using the flow rate restriction device. During combined arm-crowd and bucket operations, the device changes the flow rate parameter from unrestricted to restricted, ensuring that sufficient pressure oil is directed to the bucket directional control valve while maintaining adequate flow to the arm. This parameter adjustment resolves the contradiction between maintaining smooth arm operation and ensuring adequate pressure oil supply to the bucket.
3Quantity of substance
If auxiliary switching valve constricts supply passage to second arm directional control valve, then upstream pressure increases and pressure oil flows to boom directional control valve, but this configuration does not address combined arm-crowd and bucket operation
Solution Approach 1:
The patent applies dynamics by using a variable flow rate restriction device that can adjust its restriction level based on operational conditions. Unlike the fixed auxiliary switching valve in prior art that only addressed boom operations, this dynamic device can adapt to different operational modes including combined arm-crowd and bucket operations. The variable restriction capability allows the system to optimize pressure oil distribution for different work scenarios, thereby improving versatility while ensuring adequate pressure supply to the bucket directional control valve.
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 ensures smooth operation of both the arm and bucket cylinders, enhancing the operability and efficiency of combined arm-crowd and bucket operations by prioritizing pressure oil supply to the bucket directional control valve, thereby improving working efficiency in tasks like soil leveling and ground compaction.
Implementation Method 1
a flow rate restriction device that restricts the flow rate of pressure oil supplied to the second arm directional control valve
Implementation Method 2
the flow rate restriction device includes a variable throttle whose opening is controlled to become smaller as the bucket operating device is operated
Implementation Method 3
an electromagnetic switching valve to adjust flow based on operational demands
Data Source
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AI summary
The operability when performing a combined arm-crowd and bucket operation can be improved. A hydraulic drive device for a hydraulic excavator includes: a bucket directional control valve 16 and a second arm directional control valve 18, which are connected in parallel tandem with a first hydraulic pump 11; a first arm directional control valve 21 that is connected to a second hydraulic pump 12; and a flow rate restriction device that restricts the flow rate of pressure oil supplied to the second arm directional control valve 18, during crowd operation of a bucket 6. This flow rate restriction device includes a variable throttle 30 whose opening is controlled so as to become smaller as a bucket operating device 28 is operated to the crowd side, the variable throttle 30 being provided in a bypass path 29a connecting to the supply port of the second arm directional control valve 18.