Internal Ventilation Hood for Rotary Machine Cooling Air Retention
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Solution Overview
Problem
Existing electrodynamic rotary machines suffer from inadequate cooling due to the loss of cooling air as it exits the ventilation hood, leading to increased temperatures and thermal stress on the drive side, which limits their performance and service life.
Innovation Solution
The design incorporates air guiding elements on the hood that direct cooling air along the housing for a longer residence time, generating an additional cooling air flow by sucking in fresh air radially and directing it inwardly at an angle, enhancing the cooling effect by mixing with the main cooling air flow and increasing the axial length of the cooling effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is drawn in axially through the ventilation hood, then cooling function is provided, but cooling air escapes radially from the finned area and loses cooling effect
Solution Approach 1:
The invention changes the airflow direction from purely axial to a combination of axial and radial components by angling the air guide surfaces. The air guide surfaces are angled relative to the axis, causing cooling air to be directed both axially along the housing and radially inward toward the machine axis, extending the cooling path and preventing premature escape of cooling air
2Temperature
If the axial path of cooling air is extended towards the drive side, then cooling coverage is improved, but cooling air is depleted and loses cooling capacity
Solution Approach 1:
The invention utilizes the existing kinetic energy of the main cooling airflow to automatically draw in additional fresh air through the air guide element openings. The cooling airflow itself serves to generate the additional cooling air, creating a self-reinforcing cooling effect that extends cooling capacity along the axial path without requiring external energy input
Solution Approach 2:
The air guide element acts as an intermediary device that introduces additional fresh air into the cooling path. It has openings that allow ambient air to be drawn in and mixed with the main cooling airflow, replenishing the cooling air volume that would otherwise be depleted along the extended axial path
3Temperature
If air guide surfaces are angled relative to the axis, then additional cooling airflow is generated, but manufacturing complexity increases
Solution Approach 1:
The invention integrates the air guide element directly into the hood structure, combining two separate components (hood and air guide element) into a single molded part. This merging eliminates the need for separate assembly operations and reduces manufacturing steps, offsetting the increased complexity of creating angled surfaces within the mold
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 significantly improves the cooling function, reduces the axial temperature gradient, lowers the overall temperature of the machine, and increases the service life of windings and bearings, thereby enhancing the efficiency of the electrodynamic rotary machine.
Implementation Method 1
During operation of the fan—and thus the electrodynamic machine—fresh air is drawn in radially from the outside, in addition to the main cooling airflow, according to the principle of an injector, thus generating the additional cooling airflow
Implementation Method 2
The cooling air exits the hood and ideally moves within or between the housing fins along the housing from the ventilation side to the drive side
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a self-ventilated electrodynamic rotary machine (1), comprising a housing (6), which at least partly axially extends around the rotary machine (1). The electrodynamic rotary machine (1) has a drive side and a ventilation side. On the ventilation side, at least one fan (2) is connected to a shaft (9) for conjoint rotation and, when said shaft (9) rotates about an axis (10), generates a main air flow (7). The fan (2) is provided with a cover (3), which directs the main cooling air flow (7) generated by the fan (2) onto the housing (6). Means which at least improve the cooling of the housing are provided on the cover (3).