Denso has filed a patent for a rotor core design that includes a shaft hole and keys. The radial distance from the center of the shaft hole to the inner wall varies depending on the position in the circumferential direction. The shaft hole also includes key regions, increased diameter regions, and contact regions, which are arranged at equal intervals. The design aims to improve the performance and stability of the rotor core. GlobalData’s report on Denso gives a 360-degree view of the company including its patenting strategy. Buy the report here.
According to GlobalData’s company profile on Denso, battery management systems was a key innovation area identified from patents. Denso's grant share as of September 2023 was 33%. Grant share is based on the ratio of number of grants to total number of patents.
A rotor core with variable radial distance and key regions
A recently filed patent (Publication Number: US20230318378A1) describes a rotor core for use in various applications. The rotor core is made up of stacked magnetic steel sheets and includes a shaft hole for inserting a shaft. The core also features a key, which is a protrusion that matches the shape of a keyway in the shaft. The key projects from the inner wall of the shaft hole and extends along the central axis of the shaft hole. Importantly, there is a gap between the key and the keyway when the shaft is inserted into the shaft hole.
The radial distance from the center of the shaft hole to the inner wall of the shaft hole varies depending on the position measured in the circumferential direction of the shaft hole. The shaft hole is divided into key regions and increased diameter regions, with a total of three or more of these regions. Each key region contains the key and includes portions adjacent to the key on opposite sides in the circumferential direction. The radial distance in these portions is longer than the radius of the shaft. Similarly, the radial distance of each increased diameter region is longer than the radius of the shaft. The key regions and increased diameter regions are arranged in the circumferential direction.
The shaft hole also includes contact regions on the inner wall, located between the key regions or between the increased diameter regions. When the shaft is inserted into the shaft hole, the shaft and the inner wall come into contact with each other in these contact regions. The contact regions are evenly spaced at equal intervals in the circumferential direction.
In one embodiment, there are two key regions, a first key region and a second key region, located opposite each other in the circumferential direction. The increased diameter regions are positioned in the middle between these key regions. The number of contact regions can be four or eight.
In another embodiment, there are six contact regions, arranged at the middle position between the first key region and the second key region. Each contact region is located on opposite sides of one of the increased diameter regions. The increased diameter regions include a first adjacent region, a second adjacent region, and a central region. The distance from the center of the shaft hole to the inner wall gradually increases towards the central region in the first and second adjacent regions, while the radial distance remains constant within the central region.
Overall, this patent describes a rotor core design that allows for precise alignment and contact between the shaft and the inner wall of the shaft hole, ensuring efficient operation in various applications.