Variable Displacement Pump Control Decoupling
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Solution Overview
Problem
Existing variable displacement pumps for hydraulic transmission controls in automatic transmissions face issues with instability due to interdependencies between primary and secondary pressure control systems, leading to time delays and control instabilities.
Innovation Solution
The introduction of a switching valve allows for independent control of the primary and secondary hydraulic circuits, enabling separate control loops and preventing simultaneous intervention by multiple pressure signals, thus decoupling the pump control and transmission control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary pressure control valve and pump controller are connected in cascade (series), then the primary pressure can be regulated, but the pump control becomes active with a time delay and the control systems influence each other's behavior leading to instability
Solution Approach 1:
The patent divides the control system into two independent parallel control loops: one for primary pressure regulation and one for pump output control. The switching valve separates the control paths, allowing each loop to operate independently without time delays or mutual interference, thus resolving the stability and response time issues of cascade control.
Solution Approach 2:
The switching valve acts as an intermediary that directs control signals to either the primary pressure control valve or the pump controller based on system conditions. This mediator enables seamless transition between control modes and prevents the time delay and instability problems associated with cascade control by allowing simultaneous independent operation of both control loops.
2Adaptability or versatility
If multiple control loops (primary pressure control valve, pump controller, and pressure reducing valve) are activated simultaneously by the same pressure signal, then comprehensive control is achieved, but control instabilities occur due to simultaneous intervention and mutual influence
Solution Approach 1:
The patent implements dynamic control loop activation using the switching valve, which enables or disables specific control loops based on real-time system conditions. Instead of having all control loops active simultaneously, the system dynamically activates only the necessary loops, preventing control instabilities while maintaining comprehensive adaptability across different operating conditions.
Solution Approach 2:
The control system employs periodic activation of different control loops based on system state transitions. The switching valve periodically enables or disables control paths according to pressure conditions and operational requirements, allowing comprehensive control coverage while avoiding the instabilities caused by continuous simultaneous activation of all control loops.
3Reliability
If the control pressure chamber is supplied from the primary pressure circuit, then the pump controller can regulate pressure, but this creates interdependence with the primary pressure control system causing control movements to counteract each other
Solution Approach 1:
The patent segments the pressure supply paths by introducing a switching valve that can isolate the control pressure chamber from the primary pressure circuit. This segmentation creates independent control pressure supply when needed, eliminating interdependence between the pump controller and primary pressure control system while maintaining the ability to regulate pressure accurately.
Solution Approach 2:
The switching valve serves as an intermediary that controls the connection between the primary pressure circuit and the control pressure chamber. By mediating this connection, the system can choose to supply control pressure from the primary circuit when beneficial or isolate it to prevent counteracting control movements, thus reducing complexity while maintaining control accuracy.
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 solution stabilizes the control loops by allowing independent operation of the pump controller and primary pressure control valve, reducing time delays and preventing counteracting control movements, thereby enhancing the stability and efficiency of hydraulic transmission control.
Implementation Method 1
a pump controller for discharge pressure regulation, in which the outlet pressure of the pump in a compensation chamber and a control pressure adjustable by the pump controller in a control pressure chamber act on an adjustable stroke ring
Implementation Method 2
the control loops or control circuits of the pump control and the gearbox (primary pressure) control can be separated from each other by means of an (additional) switching valve
Data Source
Figure 1.1
Figure 1.2
Figure 2
AI summary
The invention relates to a variable displacement pump for hydraulic gearbox control systems, in particular a vane pump, having a variable stroke volume and having a pump regulator for outflow pressure regulation, in which the outlet pressure of the pump acts in a compensation chamber and a regulation pressure, which can be set by the pump regulator, acts in a regulation pressure chamber on an adjustable stroke ring, wherein the pressure in the regulation pressure chamber and an additional spring force adjust the stroke ring in the direction of maximum pivoting out, i.e. maximum stroke volume; and having a gearbox control system for automatic gearboxes, which (inter alia) has a primary hydraulic circuit for the elements of the gearbox that are relevant to force transmission and a primary pressure regulating valve, which opens a bypass to a secondary hydraulic circuit when the settable primary pressure is reached or exceeded and has an additional pressure-limiting function for the primary pressure if the primary pressure continues to be exceeded, and wherein the secondary hydraulic circuit acts to cool and lubricate the gearbox, and wherein the regulation loop or regulation circuits of the pump regulation system and of the gearbox (primary pressure) regulation system can be separated from each other by an (additional) switching valve and thus can be connected individually and independently or can be connected together.