Hydraulic Lowering Circuit With Dual-Function Proportional Relief Valve
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Solution Overview
Problem
Existing circuit arrangements for load pressure-optimized lowering in industrial trucks are complex and costly due to the presence of multiple valves, which complicates the regulation of lowering speed and provides redundancy, but can be simplified while maintaining essential functions.
Innovation Solution
A circuit arrangement featuring a 2/2-way blocking valve as the main sensory valve and a proportional-pressure limitation valve that serves dual functions, reducing the number of valves and enabling cost savings while maintaining redundancy through a double function that limits load pressure and controls lowering speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple valves (main valve, proportional valve, pressure limitation valve) are used in the circuit arrangement, then reliability and redundancy are improved, but device complexity and construction costs increase
Solution Approach 1:
The proportional-pressure limitation valve is designed to perform multiple functions: it acts as a pressure limitation valve during lifting operations and as a proportional control valve during lowering operations. This multi-functionality eliminates the need for separate valves, reducing device complexity while maintaining the redundancy provided by the main blocking valve
Solution Approach 2:
The patent combines the functions of the pressure limitation valve and the proportional control valve into a single proportional-pressure limitation valve. This merging of functions reduces the total number of valves from four (main valve, proportional valve, pressure limitation valve, and check valve) to three, simplifying the circuit arrangement while preserving reliability through the main blocking valve's redundancy
2Ease of operation
If a proportional control valve and pressure limitation valve are used separately, then load-independent lowering speed regulation is achieved, but the number of valves and construction complexity increase
Solution Approach 1:
The proportional-pressure limitation valve is designed to perform multiple functions: it acts as a pressure limitation valve during lifting operations and as a proportional control valve during lowering operations. This multi-functionality eliminates the need for separate valves, reducing device complexity while maintaining the redundancy provided by the main blocking valve
Solution Approach 2:
The proportional-pressure limitation valve dynamically switches between two operational modes: as a pressure limitation valve during lifting and as a proportional control valve during lowering. This dynamic functionality allows a single valve to replace multiple static valves, reducing construction complexity while maintaining ease of operation for load-independent lowering speed regulation
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 allows for sensitive, load-independent lowering with redundancy, preventing load crashes even if one valve fails, and reduces construction complexity and costs by eliminating an additional valve, ensuring efficient operation and safety.
Implementation Method 1
a proportional-pressure limitation valve (38), which limits the load pressure that prevails in the influx when the load is lifted
Implementation Method 2
a blocking valve (22) which blocks or releases the return line (18) as a main sensory valve
Implementation Method 3
a check valve (14) arranged in the access line (12), which opens in the direction of the pressure supply connection (P) and prevents the backstream in the Pump (6)
Data Source
Figure 1
Figure 2
AI summary
2. A circuit arrangement for load-pressure-optimized lowering of loads by means of a fluidically driven working device (28), in particular in the form of at least one hydraulic working cylinder, which can be supplied by a motor-pump unit (4) with a fluid of a predeterminable pressure in the inlet (12) for lifting the respective load, and with a return line (18) for draining fluid from the working device (28) when lowering this load, in which a proportional valve (24; 38) is connected, is characterized in that a proportional pressure relief valve (38) is connected in the return line (18), which performs a dual function by serving as a pressure relief valve or as a proportional valve when lifting and lowering the load by means of the hydraulic working device (28).