Hydraulic Fluid Temperature Engine Speed Control
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Solution Overview
Problem
Current hydraulic systems in self-propelled work vehicles face challenges during cold starts, where the charge pressure exceeds the rated capabilities of the oil cooler, leading to potential damage and contamination from unfiltered oil, especially at low temperatures.
Innovation Solution
Implementing a system that controls engine speed based on hydraulic fluid temperature, preventing premature increases in engine speed until the fluid reaches specific temperature thresholds to ensure safe operating conditions and reduce bypass flow, thereby protecting the hydraulic system and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If engine speed is increased during cold start, then productivity is improved, but hydraulic fluid temperature is too low causing damage and contamination
Solution Approach 1:
The system performs preliminary warming of the hydraulic fluid by maintaining low engine speed until the fluid reaches a safe temperature threshold. This preliminary action prevents damage before it occurs by ensuring the fluid is warmed adequately before full engine speed is engaged.
Solution Approach 2:
The engine speed is made dynamic rather than static, automatically adjusting based on hydraulic fluid temperature. The controller modulates engine speed to maintain optimal operating conditions, increasing speed only when temperature permits, thus resolving the contradiction between productivity and reliability.
2Power
If charge pressure is increased to overcome relief valve spring force, then hydraulic flow is improved, but bypass valve allows unfiltered oil to reach the system causing contamination
Solution Approach 1:
The system changes the operating parameters by controlling engine speed based on temperature. During cold conditions, engine speed is limited which indirectly controls charge pressure to stay below the bypass valve threshold, preventing contamination while still allowing adequate hydraulic flow when temperature permits.
3Temperature
If engine speed is limited during cold start, then hydraulic fluid temperature control is improved, but productivity is reduced
Solution Approach 1:
The system performs preliminary warming at reduced engine speed until temperature thresholds are met, then transitions to normal operating speed. This ensures temperature control during startup while maintaining productivity once conditions permit.
Solution Approach 2:
The controller uses temperature sensor feedback to dynamically adjust engine speed. When temperature reaches the threshold, the system transitions from limited speed to full speed, optimizing both temperature control and productivity through continuous monitoring and adaptive response.
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 approach reduces the risk of damage to the hydraulic system, minimizes unfiltered bypass oil and contamination, and allows for the use of lower-cost, lower-pressure charge pumps with extended life, while ensuring the hydraulic fluid is warmed adequately for efficient operation.
Implementation Method 1
As the pressurized hydraulic fluid moves into or through the chambers, the pressure of the fluid acts on hydraulic surfaces of the chambers to affect movement of the actuator
Implementation Method 2
charge oil is pumped from a reservoir, through an oil cooler 14 and filter 16 before entering the closed loop hydrostatic system
Implementation Method 3
the charge pressure must overcome the pressure differential created by the spring force of the relief valve and oil pressure on the opposite side of the valve
Implementation Method 4
a bypass valve 18 may be used to bypass the oil cooler 14 and filter 16 for system protection
Data Source
AI summary
Systems and methods are disclosed herein for fluid temperature-dependent control of engine speeds in a self-propelled work vehicle. An engine speed sensor generates signals representing an engine speed, and a temperature sensor generates signals representing a hydraulic fluid temperature. A controller receives the respective signals from the engine speed sensor and the temperature sensor. The controller is further configured, responsive to a startup command, to generate output signals preventing an increase in the engine speed to a target engine speed at least while the temperature of the hydraulic fluid is in a first temperature state. The controller may, e.g., automatically generate output signals for continuous and/or stepwise transitioning of the engine speed to the target engine speed, in accordance with a monitored temperature of the hydraulic fluid and corresponding temperature states.