Automatic Transmission Control Reducing Actuator Load
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Solution Overview
Problem
The mechanical engaging mechanism in automatic transmissions faces difficulties in switching states due to load conditions, particularly when the vehicle is traveling downhill, leading to increased driving force requirements and potential switching issues, which can result in cost and weight increases.
Innovation Solution
A control apparatus for automatic transmissions that includes a determination unit to assess the need to switch the mechanical engaging mechanism from a second state to a first state based on driving force conditions, specifically when the selected gear is the lowest forward speed gear and the driving force exceeds a predetermined threshold, allowing for reduced necessary driving force and improved switching capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driving force is increased to ensure reliable switching of the mechanical engaging mechanism, then the switching reliability is improved, but the cost and weight of the actuator increase
Solution Approach 1:
The control apparatus switches the mechanical engaging mechanism to the first state (one-way rotation restriction) in advance before the vehicle starts moving downhill. By performing this preliminary switching action while the vehicle is still stationary or moving at low speed, the system prepares the mechanism to handle the upcoming high-load downhill condition without requiring the actuator to generate excessive force during the actual gear transition.
Solution Approach 2:
The system dynamically adjusts the state of the mechanical engaging mechanism based on real-time driving conditions. The control apparatus monitors vehicle speed, acceleration, and gear position to determine when to switch between the first state (one-way rotation restriction) and the second state (two-way rotation restriction), optimizing the balance between switching reliability and actuator load throughout the driving cycle.
2Power
If the actuator size is increased to provide sufficient driving force for switching, then the switching capability is improved, but the cost increases
Solution Approach 1:
The control apparatus performs preliminary switching to the first state before high-load conditions occur, allowing the use of a smaller, more cost-effective actuator. By preparing the mechanism in advance when less force is required, the system avoids the need for an oversized actuator that would be necessary to handle peak loads directly during gear transitions.
Solution Approach 2:
The system changes the operational parameters of the mechanical engaging mechanism by switching between two distinct states: the first state with one-way rotation restriction and the second state with two-way rotation restriction. This parameter change allows the same mechanism to operate effectively under different load conditions, reducing the power requirements for the actuator.
3Adaptability or versatility
If the mechanical engaging mechanism is designed to handle high load conditions, then the switching capability under load is improved, but the weight and cost increase
Solution Approach 1:
The mechanical engaging mechanism is designed to dynamically switch between two operational states rather than being permanently configured for high-load handling. The control apparatus activates the first state (one-way rotation restriction) during downhill driving to enable smooth gear transitions without requiring the mechanism components to be oversized for constant high-load operation.
Solution Approach 2:
The system uses parameter changes by switching the rotation restriction characteristics of the mechanical engaging mechanism. In the first state, only rotation in one direction is restricted, which is sufficient for downhill driving conditions. This parameter change allows the mechanism to adapt to varying load conditions without requiring heavy-duty components for all operating scenarios.
Data Source
AI summary
A control apparatus of an automatic transmission, which includes a mechanical engaging mechanism functioning as a brake, includes a determination unit determining, when a selected gear is a lowest forward speed gear, and the mechanism is in a second state, whether to switch the mechanism to the first state, and a switching processing unit switching the mechanism to the first state based on a determination result. In the first state, only rotation of a predetermined rotational element provided in planetary gear mechanisms in a first direction is restricted. In the second state, rotation of the predetermined rotational element in both the first and second direction is restricted. The determination unit determines to switch the mechanism to the first state at least on condition that a driving force is larger than a predetermined driving force.