Variable Displacement Compressor Valve Deadband for Stable Bleed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control valves for variable displacement compressors suffer from unstable bleed function and controllability issues due to dependent opening and closing of main and sub-valves, leading to rasping sounds and potential loss of controllability when suction pressure varies near fully-closed points.
Innovation Solution
A control valve design that regulates the flow rate of refrigerant into the crankcase by using a main valve and sub-valve with a biasing member to set a deadband range, allowing the sub-valve to open under specific pressure conditions independently of the main valve, and varying the solenoid current to control valve opening points, preventing alternate opening and closing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the main valve and sub-valve are arranged in series and controlled by a single solenoid, then the device complexity is reduced, but the reliability of the bleed function deteriorates due to unstable valve operation and rasping sounds
Solution Approach 1:
The control valve is segmented into a main valve and a sub-valve with independent control mechanisms. The main valve is controlled by the solenoid while the sub-valve is controlled by a separate spring mechanism, allowing independent operation of each valve to prevent unstable alternating opening and closing
Solution Approach 2:
A spring mechanism is introduced as an intermediary element to control the sub-valve independently of the solenoid. This spring mechanism provides a separate control path for the sub-valve, ensuring stable operation and preventing the rasping sounds caused by valve interference
2Reliability
If the sub-valve is opened during steady operation, then the crank pressure control is improved, but the loss of refrigerant increases due to unnecessary bleeding
Solution Approach 1:
The sub-valve is designed to be dynamically controllable through spring force adjustment, allowing it to open only when specifically required (during startup) rather than remaining open during steady operation, thus preventing unnecessary refrigerant loss while maintaining crank pressure control when needed
3Ease of operation
If the main valve and sub-valve are controlled dependently on suction pressure, then the ease of operation is improved, but the stability of valve operation deteriorates when suction pressure varies near fully-closed points
Solution Approach 1:
The dependent control of main valve and sub-valve on suction pressure is segmented into independent control mechanisms. The main valve responds to suction pressure through the solenoid while the sub-valve is controlled by spring force, eliminating the instability caused by synchronized opening and closing near fully-closed points
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 and improves controllability by ensuring the sub-valve opens under controlled conditions, preventing rasping sounds and maintaining set pressures, thus enhancing the compressor's operational efficiency and reliability.
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
Implementation Method 3
a biasing member configured to bias the main valve element in a closing direction of the main valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Control valve (1) for a variable displacement compressor comprising: a body (5) having a discharge chamber communication port (16), a crankcase communication port (14) and a suction chamber communication port (12), wherein a main passage communicates the discharge chamber communication port (16) and the crankcase communication port (14) and a sub-passage communicates the crankcase communication port (14) and the suction chamber communication port (12); a main valve seat (22) provided in the main passage; a main valve element (30) configured to open and close a main valve by touching and leaving the main valve seat (22); a power element (6) configured to supply a drive force in a valve opening direction to the main valve element (30) according to a displacement amount of a pressure-sensing member (45), the power element (6) including the pressure-sensing member (45) for sensing a predetermined pressure-to-be-sensed and developing a displacement in an opening or closing direction of the main valve; a solenoid (3) configured to generate a force opposing the drive force of the power element (6) when the solenoid (3) electrically conducts; an actuating rod (38) configured to transmit a force generated by the solenoid (3) to the power element (6), the actuating rod (38) being coupled with the solenoid (3); a sub-valve seat (34) provided in the sub-passage; a sub-valve element (36) configured to open and close a sub-valve by touching and leaving the sub-valve seat (34); and a biasing member (42) configured to bias the main valve element (30) in a closing direction of the main valve. A range of the pressures-to-be-sensed (Ps), where the main valve and the sub-valve are simultaneously closed until the sub-valve element (36) is lifted from the sub-valve seat (34) after the main valve element (30) has been seated on the main valve seat (22), is set as a deadband, and a value of the pressure-to-be-sensed (Ps) with which to close the main valve, a value of the pressure-to-be-sensed (Ps) with which to open the sub-valve after the main valve has been closed, and pressure values at which the deadband takes place are set variably by setting a value of current supplied to the solenoid (3).