Control valve for a variable displacement compressor
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Solution Overview
Problem
Existing control valves for variable displacement compressors suffer from unstable bleed function operation due to alternating opening and closing of main and sub-valves, leading to potential loss of controllability and rasping sounds when suction pressure varies near fully-closed points.
Innovation Solution
A control valve design that includes a main valve and a sub-valve with a biasing member to set a deadband range where both valves are simultaneously closed, allowing the sub-valve to open under specific pressure conditions, and varying the solenoid current value to control the pressure values for stable operation, preventing alternating closures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both main valve and sub-valve are controlled by a single solenoid without a deadband mechanism, then the bleed function can be achieved, but the valves alternately open and close when suction pressure varies near fully-closed points, causing unstable operation and loss of controllability
Solution Approach 1:
The control valve is segmented into two independent valve elements: a main valve element and a sub-valve element, each capable of independent opening and closing operations. This segmentation allows the main valve and sub-valve to be controlled separately through the same solenoid, preventing alternating closure and enabling stable bleed function operation.
Solution Approach 2:
The control system dynamically adjusts the opening/closing sequence of the main valve and sub-valve based on suction pressure conditions. A deadband mechanism is introduced where both valves can be simultaneously closed under specific pressure conditions, creating a stable operational state that prevents oscillation and maintains controllability.
2Device complexity
If the main valve and sub-valve are arranged in series to form a series unit, then the structure is compact, but the valves alternately open and close when suction pressure varies, producing rasping sounds and unstable operation
Solution Approach 1:
While maintaining the series arrangement for structural compactness, the valve elements are segmented into distinct main and sub-components with independent control characteristics. This allows them to respond differently to pressure changes, preventing simultaneous closure and the resulting rasping sounds.
Solution Approach 2:
The control system introduces dynamic behavior where the main valve and sub-valve have different response characteristics and timing. The deadband mechanism ensures that when suction pressure varies, the valves do not close simultaneously, eliminating the harmful rasping sounds and vibrations.
3Device complexity
If the solenoid is positioned at one end of the series unit and the pressure-sensing section at the other, then the structure is simplified, but the controllability of bleed function is lost when valves alternately close
Solution Approach 1:
The valve control is segmented into two independent elements that can be selectively activated. Even with the simplified end-positioned solenoid structure, the segmented valve design allows independent control of main and sub-valves, maintaining bleed function controllability.
Solution Approach 2:
The control system employs dynamic pressure sensing and responsive valve actuation. The pressure-sensing section detects suction pressure conditions and dynamically adjusts the opening/closing timing of each valve element, ensuring reliable bleed function controllability despite the simplified structural arrangement.
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 solution stabilizes the bleed function by ensuring the sub-valve opens under conditions where the main valve is not easily opened, preventing unstable operation and maintaining controllability across varying air-conditioning states.
Implementation Method 1
a solenoid configured to generate a force opposing the drive force of the power element when the solenoid electrically conducts
Implementation Method 2
the power element including the pressure-sensing member for sensing a predetermined pressure-to-be-sensed and developing a displacement in an opening or closing direction of the main valve
Data Source
AI summary
In a control valve, the spring load of a spring, which biases a main valve element in a valve opening direction, is regulated, for instance. This allows a range of suction pressures Ps, where a main valve and a sub-valve are simultaneously closed until a sub-valve element is lifted from a sub-valve seat after a main valve element has been seated on a main valve seat, to be set as a deadband. The control valve is configured such that the value of a suction pressure Ps with which to open the sub-valve after the closing of the main valve and the pressure values at which the deadband takes place are set variably by the setting of a value of current supplied to the solenoid.