Hydraulic Drive Device for Excavator Boom and Arm Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic drive devices for working machines like hydraulic excavators face inefficiencies in combined operations of boom raising and arm crowding due to pressure loss, leading to increased fuel costs and reduced pump efficiency, as they require throttling which increases load on the hydraulic pump.
Innovation Solution
The configuration includes a third hydraulic pump supplying pressure oil to the boom cylinder through a third boom directional control valve connected in tandem with the arm directional control valve, while the first and second hydraulic pumps supply pressure oil to the arm cylinder, eliminating the need for throttles and regenerative circuits, thereby reducing pressure loss and improving pump efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed throttle is provided on the upstream side of an arm directional control valve to ensure controllability during combined operation, then controllability is improved, but pressure loss increases and pump efficiency deteriorates
Solution Approach 1:
The hydraulic system is segmented into multiple independent pump units (first hydraulic pump and second hydraulic pump), each serving specific directional control valves. This segmentation allows pressure oil to be supplied from different sources to different actuators, enabling the arm cylinder to receive pressure oil from the second hydraulic pump while the boom cylinder receives pressure oil from the first hydraulic pump through the first boom directional control valve, thereby eliminating the need for throttles and reducing pressure loss.
Solution Approach 2:
A third hydraulic pump is introduced as an intermediary component to supply pressure oil specifically to the first boom directional control valve. This intermediary pump enables the boom raising operation to have priority access to pressure oil, allowing the boom cylinder to operate independently without being constrained by the arm cylinder's pressure requirements, thus eliminating the need for throttling to ensure boom raising controllability.
2Ease of operation
If a regenerative circuit with a throttle is provided to enable arm crowding operation, then arm crowding controllability is improved, but pressure loss increases and pump efficiency deteriorates
Solution Approach 1:
The hydraulic system is divided into separate pressure oil supply paths for different operations. The second hydraulic pump is dedicated to supplying pressure oil to the arm cylinder for arm crowding operation, while the first hydraulic pump supplies pressure oil to the boom cylinder. This segmentation allows the arm cylinder to perform crowding operation without requiring a regenerative circuit with throttle, as it receives sufficient pressure oil directly from the second hydraulic pump.
Solution Approach 2:
The arm cylinder performs arm crowding operation by utilizing its own weight and the pressure oil supplied from the second hydraulic pump, without requiring a regenerative circuit. The system allows the arm to crowd down by its own weight while the second hydraulic pump supplies pressure oil to the cap side of the arm cylinder to control the descent speed, eliminating the need for throttling and associated pressure losses.
3Ease of operation
If throttles are provided to ensure controllability during combined operation, then operational control is improved, but fuel consumption increases due to reduced pump efficiency
Solution Approach 1:
The hydraulic system is segmented into multiple independent pump units, each dedicated to specific actuators or operations. The first hydraulic pump supplies pressure oil to the boom cylinder, the second hydraulic pump supplies pressure oil to the arm cylinder, and the third hydraulic pump supplies pressure oil to the first boom directional control valve. This segmentation eliminates the need for throttles to ensure operational control, as each actuator receives pressure oil from its dedicated pump source, thereby maintaining high pump efficiency and reducing fuel consumption.
Solution Approach 2:
The third hydraulic pump acts as an intermediary that supplies pressure oil to the first boom directional control valve, ensuring that the boom cylinder can receive pressure oil with priority during combined operation. This intermediary pump eliminates the need for throttles to control boom raising, allowing the system to maintain high pump efficiency and reduce fuel consumption while ensuring operational control.
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 enables efficient combined operation of boom raising and arm crowding without throttles, reducing pressure loss and fuel consumption, and enhancing overall pump efficiency and controllability.
Implementation Method 1
a first hydraulic pump which supplies pressure oil for operating the boom cylinder and the arm cylinder respectively
Implementation Method 2
a first boom directional control valve and a second arm directional control valve connected in parallel to the first hydraulic pump so that the first boom directional control valve controls a flow of the pressure oil supplied to the boom cylinder and the second arm directional control valve controls a flow of the pressure oil supplied to the arm cylinder
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To enable combined operation of boom raising and arm crowding without providing a throttle and also enable arm crowding operation in the same manner as in the case where a regenerative circuit having a throttle is provided. The invention provides a hydraulic drive device for a hydraulic excavator, including: a first hydraulic pump (11) ; a first boom directional control valve (19) and a second arm directional control valve (18) which are connected in parallel to the first hydraulic pump (11); a second hydraulic pump (12); and a second boom directional control valve (22) and a first arm directional control valve (23) which are connected in parallel to the second hydraulic pump (12) ; wherein: the hydraulic drive device also includes: a third hydraulic pump (13); a third boom directional control valve (33) connected to the third hydraulic pump (13) and controlling the flow of pressure oil supplied to a boom cylinder (7); and a third arm directional control valve (34) connected in tandem with the third boom directional control valve (33) and controlling the flow of pressure oil supplied to an arm cylinder (8).