Swash Plate Compressor Control With Closed-Loop Pressure Feedback
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Solution Overview
Problem
Existing variable displacement swash plate compressors suffer from pressure losses due to bleed ports, leading to inefficiencies and instability in temperature control, with suction pressure regulation being open-loop and prone to static errors and hysteresis effects.
Innovation Solution
A compressor control module (CCM) with a 4-way control valve and sensors to regulate pressure in both directions, using closed-loop control with feedback from swash plate angle and piston stroke length to precisely adjust the swash plate angle and compressor output, incorporating a Model Predictive Control (MPC) or Multi-Input-Single-Output (MISO) controller for dynamic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed orifice (bleed port) is used to communicate the crank chamber with the suction chamber, then the construction is simple, but pressure losses occur that could otherwise be used for cooling
Solution Approach 1:
The patent removes the fixed orifice (bleed port) from the system entirely. Instead of using a fixed orifice to communicate the crank chamber with the suction chamber, the invention uses a controllable valve mechanism that can open or close the passage as needed, eliminating the continuous pressure loss pathway while maintaining construction feasibility
Solution Approach 2:
The invention transitions from a static fixed orifice to a dynamic controllable valve system. The valve can adjust the degree of opening based on operational requirements, allowing the system to optimize between pressure loss prevention and cooling needs dynamically rather than being constrained by a fixed geometry
2Device complexity
If the bleed port is used to equalize pressure between crank chamber and suction chamber, then the control mechanism is simple, but the swash plate angle control becomes unstable in certain conditions
Solution Approach 1:
The patent implements a feedback control system where the actual swash plate angle or piston stroke length is measured and fed back to the controller. The controller adjusts the valve opening based on the difference between the actual and desired values, ensuring stable control of the swash plate angle across various operating conditions rather than relying on simple pressure equalization
3Stability of the object's composition
If open-loop regulation of suction pressure is used, then the construction is mostly stable, but there is no feedback that the actual suction pressure is achieved, leading to static errors and hysteresis effects
Solution Approach 1:
The patent introduces a feedback loop that measures the actual suction pressure and feeds this information back to the controller. The controller uses this feedback to adjust the valve opening and swash plate position to achieve the desired suction pressure, eliminating static errors and hysteresis effects while maintaining construction stability through proven valve and control mechanisms
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
Enhances compressor efficiency and stability by reducing pressure losses and improving temperature control precision, reducing energy consumption and manufacturing costs, while addressing controllability issues.
Implementation Method 1
The inclination angle of the swash plate, in turn, is typically regulated by varying a pressure difference between a crank chamber of the variable displacement swash plate compressor and suction chamber thereof
Implementation Method 2
The electronic control valve used by a so-called 'externally controlled variable compressor' typically includes an actuating rod driven by an electronic actuator such as a solenoid
Data Source
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AI summary
Provided compressor control module, CCM, adapted to control an output of a variable displacement swash plate compressor, it is an object of the present invention to improve the efficiency of the compressor. The object is solved by: either directly calculate, or receive from an external source, for example the HVAC control unit, a signal indicating the desired or required output from the variable displacement swash plate compressor (30), also referred to as control target or set value, for example, but not limited to, a suction pressure, a piston stroke length, an evaporator outlet air temperature, a refrigerant mass flow and/or a work done on fluid; receive the current / actual value of the value; receive or calculate the current rotation speed and angle, with respect to the rotation axis, of the swash plate, or the current piston stroke length and its reciprocating frequency, respectively, (48) of the variable displacement swash plate compressor; receive or calculate optionally additional current values of the compressor, the air conditioning system or from the vehicle, like the discharge pressure, the crank case pressure, the delta pressure between suction pressure and crank case pressure, the evaporator outlet air temperature, the engine speed, but not limited to; determine the difference between the desired or required output from the variable displacement swash plate compressor and the current output of the variable displacement swash plate compressor; and output a signal to the valve driving unit which will adjust the angle of the swash plate (48) such that the actual output of the variable displacement swash plate compressor becomes closer to, or the same as, the desired or required output as obtained in step a), also taking into account the additional values received or calculated in c) and d).