Motor-Load Interface Sealing with Dual Seals Against Fluid Ingress
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Solution Overview
Problem
Existing electric motor designs that drive fluidic loads, such as electrohydrostatic actuators, face challenges in protecting the motor from fluid ingress, leading to potential damage, degradation, and increased size, weight, and cost due to the need for protective sleeves and larger coils.
Innovation Solution
A sealing arrangement is introduced that includes a rotating shaft with a shoulder and two seals: a major seal radially extending around the shaft and a minor seal axially spaced, along with a seal holder block and drain channels to manage microleakages, allowing for effective isolation of the motor from the fluidic load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective sleeve is used to protect the motor from fluid ingress, then the motor is protected from fluid damage, but the motor size and weight increase due to the sleeve and larger coils required to compensate for Eddy current losses
Solution Approach 1:
The invention extracts and removes the protective sleeve from the motor design by implementing effective sealing at the motor-load interface. This eliminates the sleeve and its associated Eddy current losses, allowing the use of smaller, lighter coils while maintaining motor protection from fluid ingress.
Solution Approach 2:
The invention introduces sealing elements (seals and seal holder block) as intermediaries at the motor-load interface to prevent fluid ingress. These seals act as mediators that protect the motor from fluid damage without requiring the motor to be immersed in fluid or equipped with a protective sleeve.
2Reliability
If a protective sleeve is used to protect the motor from fluid ingress, then the motor is protected from fluid damage, but the motor size increases due to the sleeve and larger coils required to provide sufficient torque
Solution Approach 1:
The invention extracts and removes the protective sleeve from the motor design by implementing effective sealing at the motor-load interface. This eliminates the sleeve and its associated space requirements, allowing for a more compact motor design with smaller coils that can provide sufficient torque without the volume penalty of a protective sleeve.
3Adaptability or versatility
If the motor is designed as a wet or immersed motor with protective sleeves, then the motor can operate in a fluid environment, but the device complexity increases due to the need for sleeves, oil flow passages, and additional cooling components
Solution Approach 1:
The invention extracts and removes the protective sleeve and oil flow passages from the motor design by implementing effective sealing at the motor-load interface. This simplifies the motor structure by eliminating the need for wet motor components while maintaining the ability to operate in fluid environments through proper sealing.
Solution Approach 2:
The invention introduces sealing elements (seals and seal holder block) as intermediaries at the motor-load interface to enable the motor to operate in fluid environments without requiring complex wet motor designs. These seals act as mediators that provide fluid isolation while maintaining a simple, dry motor structure.
4Power
If larger coils are used to provide sufficient torque in a wet motor, then adequate torque is achieved, but the heat to be dissipated increases requiring fans or heat sinks
Solution Approach 1:
The invention extracts and removes the protective sleeve that causes Eddy current losses, allowing the use of smaller coils to provide the same torque output. This reduces the amount of copper in the coils, thereby reducing I²R losses and heat generation, eliminating or reducing the need for fans or heat sinks.
5Weight of moving object
If a dry motor is used without protective sleeves, then the motor size and weight are reduced, but the motor cannot be protected from fluid ingress without sealing technology
Solution Approach 1:
The invention introduces sealing elements (seals and seal holder block) as intermediaries at the motor-load interface to protect the dry motor from fluid ingress. These seals act as mediators that provide fluid isolation while allowing the motor to remain lightweight and sleeveless.
Solution Approach 2:
The invention applies sealing specifically at the critical motor-load interface where fluid ingress is most likely to occur, rather than providing universal protection through a protective sleeve. This localized sealing approach maintains the lightweight advantage of dry motors while providing targeted protection where it is most needed.
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 sealing arrangement enables the use of a dry motor with improved sealing, reducing the risk of fluid ingress and allowing for a smaller, lighter, and more cost-effective actuator design by eliminating the need for protective sleeves and larger coils.
Implementation Method 1
pressure acting on an axially outer surface of the shoulder causes the first seal to create a seal with the seal holder block against fluid flow past the shoulder
Implementation Method 2
the second seal prevents flow of any fluid that has passed the first seal passing the second seal
Data Source
Figure 1
AI summary
A sealing arrangement for the interface between a fluidic load (30) and a motor (10), the sealing arrangement comprising: a rotating shaft (20) having a shaft body (21) extending along an axis (A) and having a first end (22), configured to, in use, be in driving engagement with a fluidic load, and a second end (23) configured to, in use, be in engagement with a motor (10) for rotation by the motor, the rotating shaft and a shoulder (25) extending radially outwards from the shaft body at the first end; wherein the sealing arrangement further comprises: a first, major seal (60) extending radially around the shaft; a second, minor seal (70) axially spaced from the first seal towards the second end and mounted around the shaft, and a seal holder block (55) located between the first seal and the second seal around the shaft body; the seals arranged such that pressure acting on an axially outer surface of the shoulder (25) causes the first seal (60) to create a seal with the seal holder block (55) against fluid flow past the shoulder (25), and wherein the second seal prevents flow of any fluid that has passed the first seal passing the second seal.