Brushless DC Motor Hydraulic Pump Axial Coupling
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Solution Overview
Problem
Existing hydraulic systems with brushless DC motors and hydraulic pumps face challenges in achieving high operational reliability and compactness due to issues like unbalance, noise emission, and magnetic interference, particularly in space-constrained applications.
Innovation Solution
The hydraulic system features a motor rotor and pump rotor as separate components with axially displaceable rotary coupling and dual-sided support, incorporating a pretensioning spring for axial tensioning, which reduces unbalance risks and optimizes the magnetic situation, allowing for compact and powerful hydraulic pressure supply units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the motor rotor and pump rotor are integrated as a single common rotor, then the space requirements are reduced and power density is improved, but the manufacturing complexity and cost increase significantly, and operational reliability decreases due to unbalance and noise issues
Solution Approach 1:
The patent divides the rotor system into two separate components: a motor rotor and a pump rotor. These are manufactured independently and then coupled together, allowing each to be optimized for its specific function while maintaining compact overall dimensions. The motor rotor contains the magnetic circuit and windings, while the pump rotor contains the hydraulic pumping elements, eliminating the need for a single complex integrated rotor.
Solution Approach 2:
The patent introduces a coupling mechanism as an intermediary element between the motor rotor and pump rotor. This coupling allows the two separate rotors to be mechanically connected for rotation while maintaining their structural independence. The coupling transmits rotational motion from the motor rotor to the pump rotor, enabling functional integration without requiring a single monolithic rotor structure.
2Device complexity
If the motor rotor is supported only at one end (cantilevered), then the structure is simplified, but manufacturing complexity increases to avoid imbalance, and noise emissions increase
Solution Approach 1:
The patent employs asymmetric support configuration where the motor rotor is supported at one end by a bearing in the housing, while the pump rotor is supported at its opposite end by a bearing in the pump housing. This asymmetric arrangement allows each rotor to be supported optimally for its specific mass distribution and functional requirements, reducing vibration and noise while maintaining structural simplicity.
3Device complexity
If the bearing journal extends through the motor rotor to support the common rotor, then the support structure is simplified, but the magnetic situation within the motor rotor is impaired, leading to performance loss
Solution Approach 1:
The patent segments the support structure into two separate bearing locations: one bearing supports the motor rotor in the housing, and another bearing supports the pump rotor in the pump housing. This segmentation eliminates the need for a through-journal that would disrupt the magnetic circuit, allowing the motor rotor to maintain its optimal magnetic configuration while still providing adequate support for both rotors.
4Ease of manufacture
If low-cost materials with high thermal expansion coefficient are used for motor rotor manufacturing, then manufacturing cost is reduced, but tolerance compensation becomes more difficult
Solution Approach 1:
The patent introduces a preload spring that applies axial force to the coupling between motor rotor and pump rotor. This dynamic element compensates for thermal expansion variations by maintaining constant contact pressure between the rotors. As temperature changes cause expansion or contraction, the spring adjusts the axial position to maintain proper alignment and clearance, ensuring consistent performance across different operating temperatures without requiring expensive tight-tolerance materials.
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 configuration enhances operational reliability, reduces noise, and optimizes performance by compensating for manufacturing tolerances and thermal expansion, resulting in more efficient and cost-effective hydraulic systems.
Implementation Method 1
a preload spring (39) is provided which is supported on the pump rotor (10) and acts with axial tension on the motor rotor (23)
Implementation Method 2
compensating for manufacturing tolerances and thermal expansion
Data Source
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AI summary
In a hydraulic system with a hydraulic pressure supply unit (5) and at least one hydraulic consumer (6) that can be actuated by it, the pressure supply unit (5) comprises a housing structure (28) and a hydraulic pump (9) driven by an electric motor (11), which is designed as a brushless DC motor with an external motor stator (22) and an internal motor rotor (23). The pump pump includes a pump rotor (10) rotatably mounted on a bearing journal (13) and rotaryally coupled to the motor rotor (23). The motor rotor (23) and the pump rotor (10) are separately manufactured components. The rotary coupling of the pump rotor (10) to the motor rotor (23) is axially displaceable. The motor rotor (23) is rotatably mounted at a first bearing point (26) on the housing structure (28) and at a second, opposite bearing point (33) on the bearing journal (13).