Patent Application
20240159306
The present disclosure relates to a multi-slot gear blank. More particularly, the present disclosure relates to a multi-slot gear blank optimized for high performance applications having reduced noise, vibration, handling (NVH) and reduced mass.
NVH and light weighting of gears have become more important engineering challenges for electrical vehicle programs. For example, reduced NVH is important with quitter electric motors while reduced weight improves vehicle battery range. In particular, transfer gears located between motors and drive shafts may have NVH issues, such as noise, due to the high torque that is applied to the transfer gear. One solution is to use additional components, such as an acoustic blanket surrounding the transfer gear, to reduce noise issues. While effective, there is a need in the art for improved gear designs that include slots to reduce local stress concentration, which enables the design to be used in high performance applications where high torque is applied, while also reducing NVH and reducing gear weight.
A multi-slot gear for a powertrain of a vehicle is provided. The multi-slot gear includes an inner ring, an outer ring having gear teeth disposed on a periphery of the outer ring, a web disposed between the inner ring and the outer ring, and a plurality of slots disposed within the web. Each of the plurality of slots includes a slot angle and each of the plurality of slots is separated from one another by a space angle. The ratio of the slot angle to the space angle is greater than 2.
In one aspect, the plurality of slots includes more than four slots.
In another aspect, the plurality of slots includes eight slots.
In another aspect, the slot angle is 34 degrees.
In another aspect, the space angle is 11 degrees.
In another aspect, the slot angle is defined as a radial angle measured relative to an axis, about which the inner ring and the outer ring are coaxial, from one end of one of the plurality of slots to another end of the one of the plurality of slots.
In another aspect, the space angle is defined as a radial angle measured relative to the axis from the one end of the one of the plurality of slots to a nearest end of an adjacent one of the plurality of slots.
In another aspect, the web has a web thickness, measured along an axis of the multi-slot gear, less than a thickness of the inner ring and a thickness of the outer ring.
In another aspect, the plurality of slots are each defined as portions of the web with no material that extends completely through the web.
In another aspect, each of the plurality of slots are identical and disposed symmetrically about an axis of the multi-slot gear.
In another aspect, the plurality of slots each have a slot width, measured in a radial direction from an axis of the multi-slot gear, that is less than a web width of the web, measured in the radial direction from the axis.
In another aspect, each of the plurality of slots include semi-circular ends.
In another aspect, each of the plurality of slots is arcuate.
According to another embodiment, a multi-slot gear for a powertrain of a vehicle is provided. The multi-slot gear includes an inner ring, an outer ring having gear teeth disposed on a periphery of the outer ring, a web disposed between the inner ring and the outer ring, and a plurality of slots disposed within the web. Each of the plurality of slots includes a slot angle. Each of the plurality of slots is separated from one another by a space angle. The ratio of the slot angle to the space angle is greater than 2 and less than 5, and the plurality of slots includes more than four slots.
In one aspect, the plurality of slots includes eight slots.
In another aspect, the slot angle is defined as a radial angle measured relative to an axis, about which the inner ring and the outer ring are coaxial, from one end of one of the plurality of slots to another end of the one of the plurality of slots.
In another aspect, the space angle is defined as a radial angle measured relative to the axis from the one end of the one of the plurality of slots to a nearest end of an adjacent one of the plurality of slots.
In another aspect, the web has a web thickness, measured along an axis of the multi-slot gear, less than a thickness of the inner ring and a thickness of the outer ring.
In another aspect, the plurality of slots each have a slot width, measured in a radial direction from an axis of the multi-slot gear, that is less than a web width of the web, measured in the radial direction from the axis.
According to another embodiment of the present disclosure, a powertrain for a vehicle is provided. The powertrain includes a motor having an output shaft, an output gear disposed on the output shaft, a transfer shaft, and a multi-slot gear disposed on the transfer shaft and in mesh with the output gear. The multi-slot gear includes an inner ring, an outer ring having gear teeth disposed on a periphery of the outer ring, a web disposed between the inner ring and the outer ring, and a plurality of slots disposed within the web, wherein each of the plurality of slots includes a slot angle, and wherein each of the plurality of slots is separated from one another by a space angle, wherein the ratio of the slot angle to the space angle is greater than 2. The powertrain further includes a transfer gear disposed for co-rotation on the transfer shaft, a driveshaft, and a driven gear disposed on the driveshaft and in mesh with the transfer gear, wherein output torque from the motor is transferred from the output shaft and the output gear to the multi-slot gear, the multi-slot gear rotates the transfer shaft and the transfer gear to transfer torque to the driven gear and the driveshaft.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Referring to
The multi-slot gear 10 is designed using multibody dynamic analysis to determine the most influential parameters to NVH, stress, and light-weighting. First, a time varying mesh stiffness of the multi-slot gear 10 is calculated using system modelling of shafts, bearings gears, as well as geometric and kinematic boundary conditions. Multibody dynamic analysis includes identifying the flexible bodies in the system (housing, shafts, stators), time varying mesh stiffness from the previously performed system modeling, and running a simulation to determine vibration responses, forces, etc. Then, an acoustic analysis is performed to determine if noise is reduced using the multi-slot gear design.
Turing to
A plurality of slots 44 are disposed through the web 42. The slots 44 are defined as portions of the web 42 with no material that extend completely through the web 42 of the multi-slot gear 10. Each of the slots 44 are identical and disposed symmetrically about the axis 34. The slots 44 each have a slot width 46, measured in a radial direction from the axis 34. The slot width 46 is less than a web width 48, measured in the radial direction from the axis 34. Each of the slots 44 is arcuate with ends 50. In one non-limiting aspect, the ends 50 are each semi-circular, though other shapes may be employed. and is defined by a slot angle 52. The slot angle 52 is defined as a radial angle measured relative to the axis 34 from one end 50 of one slot 44 to another end 50 of the one slot 44. The distance between adjacent slots 44 is defined by a space angle 54. The space angle 54 is defined as a radial angle measured relative to the axis 34 from one end 50 of one slot 44 to the nearest end 50 of an adjacent slot 44.
To design a transfer gear that meets the requirements of mass, stress, and NVH, each of the parameters of the transfer gear must be adjusted and a near infinite number of combinations is possible, making optimization of the transfer gear difficult. However, the number of slots 44 and the position/size of the slots 44 relative to the web 42 have been determined using the principles of the present disclosure as the primary parameters in reducing mass, stress, and NVH issues. Accordingly, to reduce NVH issues, reduce mass, and reduce stress, a ratio of the slot angle 52 to the space angle 54 is greater than 2 for the multi-slot gear 10. In addition, the plurality of slots 44 includes more than four slots. In one embodiment, the plurality of slots 44 includes eight slots where the slot angle 52 is approximately 34 degrees and the space angle 54 is approximately 11 degrees. It should be appreciated that the term “approximately” is known to those skilled in the art. Alternatively, the term “approximately” is defined as +/−4 degrees.
With reference to
The multi-slot gear 10 described and optimized as described above provides many advantages over conventional designs. By reducing NVH, the multi-slot gear 10 can be used in high torque applications in electric vehicle programs. By reducing mass while minimizing stress, the multi-slot gear 10 improves vehicle efficiency and range.
The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.
