Planetary Gearbox Layout for Compact Starter-Generator Integration
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Solution Overview
Problem
Existing integrated starter/generator devices are often inconveniently long and interfere with equipment positioning, necessitating a compact and efficient integration of starter and generator functions.
Innovation Solution
A gearbox arrangement with a planetary gear system that includes a ring gear, ring brake, and free-wheel clutch, allowing for mechanical coupling in both power flow directions, and a mechanism to move the ring gear between engaged positions with the ring brake or carrier, optimizing gear ratios for starting and generating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If integrated starter/generator devices are provided, then starter and generator functions are combined, but the device becomes inconveniently long and interferes with equipment positioning
Solution Approach 1:
The planetary gear set is nested within the housing structure, with the ring gear forming part of the housing wall. The electric machine is positioned centrally within the planetary gear arrangement, with the sun gear aligned with the electric machine output shaft. This nested configuration allows the starter and generator functions to be integrated in a compact radial layout rather than requiring linear extension, thereby combining multiple functions while minimizing device length.
Solution Approach 2:
The invention transitions from a linear/axial arrangement to a radial/concentric arrangement by positioning the electric machine at the center of the planetary gear set. The power flow paths are arranged radially outward from the central electric machine, allowing both starter and generator functions to operate simultaneously in different radial directions without requiring extended axial length, thus solving the contradiction between integration and compactness.
2Power
If a planetary gear arrangement is used to mechanically couple the electric machine and engine, then torque requirements are managed efficiently, but the device complexity increases
Solution Approach 1:
The planetary gear set serves multiple functions simultaneously: it provides torque multiplication during engine starting, enables power generation when the engine drives the electric machine, and allows for reversible power flow between the electric machine and engine. The ring brake and free-wheel clutch are integrated into the planetary gear structure, with the ring brake serving both as a braking mechanism and as a structural component of the gear set. This multi-functionality reduces the need for separate components, thereby managing torque requirements efficiently while limiting the increase in device complexity.
3Reliability
If a ring brake and free-wheel clutch are integrated into the planetary gear set, then component damage is prevented by controlling rotational speeds, but the manufacturing complexity increases
Solution Approach 1:
The ring brake is merged with the ring gear structure, where the brake lining is applied directly to the inner surface of the ring gear. The free-wheel clutch is integrated into the planetary carrier assembly, with the clutch elements positioned to engage with the planet gears. This merging of braking and clutch functions with the planetary gear components eliminates the need for separate brake drums and clutch housings, thereby providing reliable rotational speed control and component protection while simplifying the manufacturing process compared to fully separate integrated designs.
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
Enables a compact integrated starter/generator device that efficiently manages torque requirements for engine starting and generates electrical power, preventing component damage by controlling rotational speeds and facilitating seamless operation in both modes.
Implementation Method 1
a planetary gear arrangement configured to receive rotational input from the electric machine and from the engine and to mechanically couple the electric machine and the engine in first and second power flow directions
Implementation Method 2
a ring brake, the free-wheel clutch permitting rotation of the ring brake in a first direction and preventing rotation of the ring brake in an opposite second direction
Implementation Method 3
a free-wheel clutch attached to a fixed structure and the ring brake, the free-wheel clutch permitting rotation of the ring brake in a first direction and preventing rotation of the ring brake in an opposite second direction
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A gearbox arrangement of an electric machine of an engine includes a planetary gear arrangement configured to receive rotational input from the electric machine and from the engine and to mechanically couple the electric machine and the engine in first and second power flow directions, the planetary gear set comprising a ring gear, a ring brake, a free-wheel clutch attachable to a fixed structure and the ring brake, the tree -wheel clutch permitting rotation of the ring brake in a first direction and preventing rotation of the ring brake in an opposite second direction, and an arrangement for moving the ring gear between a first position in which the ring gear is non-rotatably engaged with the ring brake and a second position in which the ring gear is non-rotatably engaged with the carrier. An engine starter and power generator device Is also provided.