Expansion Machine Shaft Seal Pressure Regulation
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Solution Overview
Problem
Expansion machines with shaft sealing rings face leakage issues when operated under negative pressure, as the pressure difference between the sealing lip and the surrounding environment is reversed, leading to a loss of sealing effect.
Innovation Solution
The expansion machine incorporates a valve system that regulates pressure in the valve chamber, ensuring it remains at least as great as the surrounding pressure, maintaining a consistent sealing effect across all operating states, including negative pressure conditions, by connecting the valve chamber to areas with higher pressures, such as the inflow area or outflow area, and using a valve with a closing body and membrane to control hydraulic connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft seal is positioned with the sealing lip facing the high-pressure side (positive pressure operation), then sealing effectiveness is improved under positive pressure conditions, but sealing effectiveness deteriorates under negative pressure conditions
Solution Approach 1:
The invention introduces a valve that can dynamically switch the pressure condition in the valve chamber between positive and negative pressure states. This allows the shaft seal to maintain its sealing effectiveness by ensuring the sealing lip always faces the higher pressure side, regardless of the overall operating pressure of the expansion machine.
Solution Approach 2:
The invention changes the pressure parameter in the valve chamber by introducing a controllable valve. The valve can adjust the pressure differential across the shaft seal, ensuring that the sealing lip remains pressed against the shaft even when the expansion machine operates under negative pressure conditions.
2Ease of operation
If the expansion machine operates under negative pressure with conventional shaft seal arrangement, then the sealing lip is lifted from the shaft, but this causes working medium leakage into the surrounding space
Solution Approach 1:
The valve dynamically adjusts the pressure in the valve chamber to maintain a positive pressure differential across the shaft seal during negative pressure operation. This prevents the sealing lip from lifting and eliminates working medium leakage while enabling negative pressure operation.
Solution Approach 2:
The valve chamber acts as an intermediary space between the working medium and the surrounding environment. By controlling the pressure in this intermediate chamber, the invention prevents direct leakage paths while allowing the expansion machine to operate under negative pressure conditions.
3Adaptability or versatility
If a separate housing is used for the valve, then valve functionality is achieved, but device complexity and space requirements increase
Solution Approach 1:
The invention merges the valve housing with the expansion machine housing, eliminating the need for a separate valve housing. This integration reduces device complexity and space requirements while maintaining full pressure regulation capability for controlling the shaft seal operation.
Solution Approach 2:
The housing serves multiple functions: it contains both the expansion machine components and the valve mechanism. This multi-functional design reduces the overall number of components and simplifies the device structure while maintaining all necessary functionalities.
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 solution allows the expansion machine to operate without leakage in both overpressure and vacuum conditions, extending its operational range and minimizing stress on the shaft seal, thereby ensuring reliable sealing and increased service life.
Implementation Method 1
it is always advantageous for there to be a higher pressure on one side of the shaft seal than on the opposite side. This pressure difference presses a sealing lip of the shaft seal against the output shaft, thus sealing the two sides against each other
Implementation Method 2
The inlet area is hydraulically connected to the valve chamber by a throttle. This connection allows the valve chamber to be regulated by the valve to the pressure level of the inlet area
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to an expansion machine (20), comprising an output shaft (24) and a shaft sealing ring (25) that interacts with the output shaft. The expansion machine (20) has an inflow region (21) and an outflow region (22). During operation, a working medium flows through the expansion machine (20), wherein compressed working medium flows into the inflow region (21) and expanded working medium flows out of the outflow region (22). The shaft sealing ring (25) separates a valve space (11) filled with working medium from a surrounding space (40). A valve (10) is arranged in the expansion machine (20). The pressure in the valve space (11) can be controlled by means of the valve (10).