Expansion Valve with Extended Mounting Stroke for Simplified Assembly
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Solution Overview
Problem
The assembly of expansion valves used in refrigerant circuits, particularly with high-pressure refrigerants like carbon dioxide, is complicated due to the need for precise tolerances to avoid leakages, making the process difficult and error-prone.
Innovation Solution
The expansion valve design features an actuator with a mounting stroke at least two times the operating stroke, allowing for easier assembly by moving the actuation element far out of the housing, enabling precise connection and assembly of parts, and incorporating a point-like contact area for reliable closure with flexible tilting capability, reducing the risk of leakages without requiring high production tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small tolerances are used to avoid leakages with high pressure refrigerant, then reliability is improved, but device complexity and assembly difficulty increase
Solution Approach 1:
The actuator is designed with an extended mounting stroke that allows the actuation element to be positioned and connected to the valve element before final assembly. This preliminary positioning action enables precise alignment and connection of the actuation element with the valve element while there is still access space, thereby achieving reliable connection without requiring complex assembly procedures or extremely tight tolerances throughout the entire device.
Solution Approach 2:
The connection between the actuation element and valve element is established in a lateral direction rather than along the primary axial stroke direction. This dimensional change allows the connection to be made when the actuation element is extended outward, providing access space for assembly without compromising the sealing reliability that would otherwise require extremely tight tolerances in the constrained axial direction.
2Reliability
If small tolerances are used to avoid leakages with high pressure refrigerant, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The extended mounting stroke enables the actuation element to be pre-positioned and connected to the valve element in a controlled manner before final housing assembly. This preliminary connection can be made with adequate access space, allowing for proper alignment and securing of the connection without requiring the entire assembly process to meet extremely tight tolerance specifications.
Solution Approach 2:
The actuator stroke parameter is changed to be at least twice the operating stroke length. This parameter change creates an extended range of motion that allows the actuation element to be positioned far outside the housing during assembly, providing the necessary space to achieve precise connections without requiring the housing itself to be manufactured or assembled with extremely tight tolerances.
3Measurement precision
If the valve element is rigidly connected to the actuation element, then positioning precision is improved, but reliability of closure decreases
Solution Approach 1:
The connection between the valve element and actuation element is designed to allow controlled tilting or angular adjustment of the valve element relative to the actuation element during operation. This dynamic capability enables the valve element to self-align with the valve seat during closure, ensuring complete sealing contact and reliable closure even if there are minor misalignments, while still maintaining precise positioning control through the actuation mechanism.
Solution Approach 2:
The connection geometry is designed with a point-like contact area, possibly formed by a spherical protrusion, which allows the valve element to tilt or rotate slightly relative to the actuation element. This parameter change in connection flexibility enables the valve element to achieve complete closure by resting its entire front face against the valve seat, thereby improving closure reliability without sacrificing positioning precision.
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 design simplifies the assembly process, reduces leakage risks, and maintains valve tightness without the need for high closing forces, ensuring precise and reliable operation of the expansion valve.
Implementation Method 1
a pressure at the inlet port acts on a first pressure area of the valve element in closing direction and on a second pressure area of the valve element in an opening direction, wherein the first pressure area is larger than the second pressure area. The pressure at the inlet port is used to produce a net force on the valve element pressing the valve element against the valve seat.
Data Source
AI summary
An expansion valve (1) is described to include a housing (2) having in inlet port (3) and an outlet port (4), a valve seat (5) arranged between the inlet port (3) and the outlet port (4), a valve element (6) movable over an operating stroke between a closed position at the valve seat (5) and an opened position away from the valve seat (5), and an actuator (7), wherein the actuator (7) has an electric rotary motor (8) acting on the valve element (5) by means of a threaded spindle (10) and a nut (9), wherein one of spindle (10) and nut (9) is rotatably driven by the motor (8) and the other one is rotatably fixed. Such an expansion valve should have the possibility for a simple assembly. To this end, in a disassembled condition of housing (2) and actuator (7), the actuator (7) has a mounting stroke which is at least two times the operating stroke, wherein the mounting stoke extends the operating stroke.