Planetary Gear Transmission with Band Brake Shift at Standstill
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Solution Overview
Problem
Existing power transmission devices face issues in switching gear shift positions from high gear speed to low gear speed when a vehicle is stopped due to skew between spline phases, preventing the engagement of the transmission switching member.
Innovation Solution
The power transmission device employs a transmission mechanism with a planetary gear set, a clutch, and a band brake, allowing gear shift position switching by changing the combination of clutch engagement and band brake operation, eliminating the need to match spline phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a meshing type engagement device is used for gear shift switching, then the transmission mechanism can achieve reliable gear engagement, but spline phase skew prevents switching when the vehicle is stopped
Solution Approach 1:
The patent replaces the meshing type engagement device with a friction type engagement device. Instead of relying on spline meshing that requires precise phase alignment, the new system uses friction-based engagement through clutch plates and brake components, allowing gear shifts to occur without spline phase coordination when the vehicle is stopped.
Solution Approach 2:
The patent changes the engagement mechanism from a mechanical meshing system with fixed geometric constraints to a friction-based system where engagement is controlled by pressure and friction coefficients. This parameter change allows the engagement destination to be switched regardless of spline phase position, enabling gear shifts at stopped conditions.
2Ease of operation
If friction type engagement elements are used for gear switching, then gear shift position can be switched without spline phase alignment, but device complexity increases
Solution Approach 1:
The patent merges the clutch and brake mechanisms into an integrated friction-type engagement system. By combining these functions, the patent reduces the need for separate engagement devices for different gear shifts, thereby managing complexity while enabling flexible gear switching without spline phase alignment.
Solution Approach 2:
The friction-type engagement elements serve multiple functions: they enable both clutch engagement and brake operation for different gear shift scenarios. This multi-functionality reduces the need for specialized components for each gear shift type, managing overall system complexity while achieving the goal of spline-phase-independent switching.
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 seamless gear shift position switching between high and low gear speeds without spline phase alignment, reducing shift shock and drag torque, and minimizing the device's size and electrical consumption.
Implementation Method 1
a band brake 49 that is engaged when the transmission mechanism 3 is at low gear speed
Implementation Method 2
a clutch 47 that is engaged when the transmission mechanism 3 is at high gear speed
Data Source
Figure 1
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AI summary
A motive power transmission device (1) includes a gearshifting mechanism (3) that has a planetary gear set (4), a first engagement element, and a second engagement element. The first engagement element is a band brake (49) which is engaged when the gearshifting mechanism is at a low-speed stage. The second engagement element is a clutch (47) which is engaged when the gearshifting mechanism is at a high-speed stage. The band brake (49) is provided so as to overlap the planetary gear set (4) in the radial direction of an axis of rotation (X) and is disposed so that the band brake (49) and the planetary gear set (4) overlap each other as seen from the radial direction of the axis of rotation (X).