Utility Vehicle Hydraulic Startup Control With Auxiliary Pump
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Solution Overview
Problem
Existing hydraulic arrangements for utility vehicles require high drive power during starting operations, especially due to increased viscosity of the hydraulic medium during cold starts, leading to increased power consumption by the displacement pump.
Innovation Solution
A hydraulic arrangement that includes a displacement pump with a displacement control unit adjustable to a reduced conveying position at startup, supported by an auxiliary pump to maintain displacement pressure and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the displacement pump is adjusted to an increased conveying position during starting operation, then the hydraulic quantity supplied to consumers is increased, but the drive power required increases significantly
Solution Approach 1:
The auxiliary pump is activated before the main displacement pump during starting operation to pre-supply hydraulic medium to the consumers. This preliminary action ensures that sufficient hydraulic quantity is available when the displacement pump is still at reduced conveying position, thereby avoiding the need to immediately increase the displacement pump's drive power to maximum levels
Solution Approach 2:
The auxiliary pump acts as an intermediary device that bridges the gap between the reduced output of the displacement pump during startup and the hydraulic consumers' requirements. It temporarily supplements the hydraulic supply, allowing the displacement pump to operate at lower power consumption while still meeting system demands
2Reliability
If the displacement pump operates at maximum conveying quantity during cold start, then the hydraulic consumers receive sufficient fluid, but the power consumption increases due to increased viscosity
Solution Approach 1:
Instead of operating the displacement pump at full capacity during cold start, the system uses partial action by activating the auxiliary pump to supplement the reduced output of the displacement pump. This approach provides sufficient hydraulic supply to consumers while keeping the displacement pump's power consumption lower than maximum levels
Solution Approach 2:
The system changes the operational parameters by introducing the auxiliary pump with different characteristics than the main displacement pump. The auxiliary pump operates independently with its own displacement and speed parameters, allowing the combined system to meet hydraulic demands while optimizing overall power consumption during cold start conditions
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
The hydraulic arrangement reduces the power required for the displacement pump during startup, relieving the load on the drive motor and starter motor, and enabling a successful cold start with lower energy expenditure.
Implementation Method 1
a displacement pressure which is generated by the activated auxiliary pump can act on the working connection
Implementation Method 2
a hydraulic working connection of the displacement cylinder is hydraulically connected to an output of the auxiliary pump
Data Source
AI summary
A hydraulic arrangement for a utility vehicle. The arrangement may include a hydraulic displacement pump which is connected via a pump output to a supply connection as a hydraulic interface for supplying hydraulic consumers of the utility vehicle. In addition, the device may include a hydraulic auxiliary pump and an auxiliary supply connection as a hydraulic interface for alternatively supplying at least some of the consumers. The device may include a displacement control unit which is dependent on an output pressure of the auxiliary pump for displacing the displacement pump in such a manner that a hydraulic working connection of a displacement cylinder of the displacement control unit is connected to an output of the auxiliary pump.