Hermetic Compressor Low Current Start via Clutch Control
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Solution Overview
Problem
Existing vapor cycle refrigerant systems in helicopters face issues with bulkiness, weight, and high maintenance due to belt-driven motion transmission and high start currents in hermetically sealed compressors, which can trigger power failures.
Innovation Solution
A medium-frequency hermetically sealed refrigerant compressor with a low current start capability, utilizing an electric connector, a medium-frequency motor, a movable disc, a motion transmission sleeve, a main shaft, a clutch coil, and a clutch friction plate, allowing for an unloaded start and reduced size and weight through a hermetically sealed structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a hermetically sealed refrigerant compressor is used, then the size and weight of the vapor cycle refrigeration system are reduced, but the start current becomes 5-7 times stronger than the working current, triggering power protection and causing power failure
Solution Approach 1:
The patent applies preliminary action by enabling the compressor to start without load before gradually engaging the load. The control system detects rotation speed and sequentially opens loading valves (first loading valve, second loading valve) after the compressor reaches a predetermined rotation speed, allowing the motor to accelerate freely before connecting to the compression mechanism. This staged load engagement prevents excessive start current while maintaining the hermetic sealed design.
Solution Approach 2:
The patent implements dynamics by making the loading state variable and controllable during startup. The control system dynamically adjusts the loading condition based on rotation speed detection, transitioning from unloaded state to progressively loaded states (first loading, second loading) as the motor accelerates. This dynamic control of load engagement allows the system to adapt the start current profile to match the motor's acceleration capability, preventing power protection triggering.
2Temperature
If belt-driven motion transmission is used, then the motor can be independently cooled with additional cooling fans and air ducts, but the system becomes bulkier and heavier
Solution Approach 1:
The patent merges the motor cooling function with the refrigeration cycle by eliminating the need for separate cooling fans and air ducts. The motor is directly coupled to the compressor within the hermetic sealed enclosure, and the refrigerant circulation system provides cooling to the motor. This integration of cooling functions into the existing refrigeration cycle removes additional cooling components, reducing overall system weight and bulk while maintaining effective motor cooling.
Solution Approach 2:
The patent applies self-service by enabling the refrigeration system's own refrigerant circulation to cool the motor without requiring external cooling mechanisms. The motor is positioned within the hermetic sealed enclosure where refrigerant flow naturally provides cooling to the motor housing and windings. This self-cooling approach eliminates the need for separate cooling fans, air ducts, and associated control systems, significantly reducing system weight and complexity.
3Speed
If belt-driven motion transmission is used, then motion can be transmitted from the motor to the compressor, but the belt occupies large space and requires good positioning and high precision installation
Solution Approach 1:
The patent replaces the belt-driven mechanical transmission system with a direct coupling mechanism. The motor shaft is directly connected to the compressor shaft through a shared main shaft within the hermetic sealed enclosure, eliminating the need for belts, pulleys, and associated tensioning mechanisms. This direct mechanical coupling achieves efficient motion transmission while minimizing the space required for the transmission mechanism and eliminating positioning and installation precision requirements associated with belt systems.
4Speed
If belt-driven motion transmission is used, then motion can be transmitted from the motor to the compressor, but the belt tension and limited service life require additional maintenance and replacement
Solution Approach 1:
The patent replaces the belt-driven mechanical transmission system with a direct coupling mechanism where the motor shaft and compressor shaft are directly connected through a shared main shaft. This eliminates belts entirely, removing the sources of belt tension issues, wear, and limited service life. The direct coupling provides reliable, maintenance-free motion transmission for the lifetime of the hermetic sealed compressor, as there are no friction-based or tension-dependent components requiring replacement.
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 achieves a low current start, reducing the impact on the on-board power supply and minimizing size and weight, while maintaining refrigeration capacity, thus addressing the bulkiness and maintenance concerns of traditional systems.
Implementation Method 1
the electric connector supplies power to the clutch coil so that the clutch coil and the clutch friction plate will be mutually attracted to each other
Data Source
Figure 1
AI summary
A medium-frequency hermetically sealed refrigerant compressor capable of unloading during start, comprising: an electric connector (2), a front end socket (1), a rear end socket (6), a barrel (7), a medium-frequency motor (3) disposed in the barrel (7), a movable disc (4), a motion transmission sleeve (8), a main shaft (9), a clutch coil (10) and a clutch friction plate (11); the front and back ends of the barrel (7) are respectively connected to the front end socket (1) and the rear end socket (6); the barrel (7) has a stator disc (5) fixed therein cooperating with the movable disc (4); the movable disc (4) and the stator disc (5) are sleeved on one side of the main shaft (9), and the clutch friction plate (11) and the clutch coil (10) are sleeved on another side of the main shaft (9); the movable disc (4) and the clutch friction plate (11) are fixed on a side surface of the main shaft (9); the output shaft of the medium-frequency motor (3) is connected to the clutch coil (10) via the motion transmission sleeve (8); the electric connector (2) is fixed on the barrel (7); and the electric connector (2) is connected to the clutch coil (10). The compressor achieves a low current start, and reduces the impact against the on-board power supply.