Drive Pump Control Circuit With Split Servo and Charge Flow
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Solution Overview
Problem
Conventional hydrostatic drive systems face inefficiencies due to conflicting pressure requirements for controlling servo valves and charging the drive circuit, leading to suboptimal performance as they can only be optimized for one function or neither.
Innovation Solution
A hydraulic charge circuit with a separate control flow path and hydraulic charge flow path is introduced, allowing for high-pressure, low-volume flow for servo control valves and low-pressure, high-volume flow for charging the hydrostatic drive circuit, using a single pump to manage both functions efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic circuit is used for both servo control and drive circuit charging, then device complexity is reduced, but pressure requirements cannot be optimized for both functions simultaneously
Solution Approach 1:
The hydraulic circuit is segmented into two separate flow paths: a control flow path for servo valves and a charge flow path for drive circuit charging. This segmentation allows each path to be independently optimized for its specific pressure requirements, resolving the contradiction between circuit simplicity and pressure optimization.
2Measurement precision
If high pressure is provided for servo control valves, then control precision is improved, but pressure for charge pump becomes suboptimal
Solution Approach 1:
By dividing the hydraulic circuit into separate control and charge flow paths, the system can provide high pressure to servo control valves for precise control while simultaneously providing optimized pressure to the charge pump for efficient operation, eliminating the trade-off between control precision and charging efficiency.
3Loss of energy
If low pressure is provided for charge pump, then energy consumption is reduced, but pressure for servo control becomes insufficient
Solution Approach 1:
The segmented hydraulic circuit allows the charge pump to operate at lower, more energy-efficient pressures while the control flow path independently provides sufficient high pressure to servo control valves, ensuring both energy efficiency and reliable control functionality.
4Device complexity
If a single pump is used for both control and charging functions, then device complexity is reduced, but performance optimization for both functions is limited
Solution Approach 1:
A single hydraulic pump is designed to perform multiple functions by supplying hydraulic fluid to two separate flow paths: one for servo control and another for drive circuit charging. This multi-functionality approach maintains device simplicity while enabling optimized performance for both control and charging operations through the segmented circuit architecture.
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 improves the overall efficiency of the system by providing sufficient pressure for servo control while maintaining optimal pressure for hydrostatic drive circuit charging, reducing complexity and cost.
Implementation Method 1
a hydraulic charge pump configured to provide a hydraulic charge flow to the hydrostatic drive circuit
Implementation Method 2
a pressure relief valve that sets a hydraulic pressure for a charge flow of hydraulic fluid to be supplied to the hydrostatic circuit
Data Source
AI summary
A control system is provided for a power machine that includes a hydraulic charge circuit with a hydraulic charge pump, and a variable displacement drive pump. A signal for control of displacement of the drive pump can be diverted from the hydraulic charge circuit downstream from the pump, including via a flow path that branches from the hydraulic charge circuit from a location upstream of a hydraulic load.