Vehicle Drive Control Device Torque Distribution Optimization
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Solution Overview
Problem
Existing vehicle drive devices struggle to optimize fuel efficiency by controlling the engine operating point, as the hydraulic characteristic of the hydraulic power transmission device constrains the torque distribution between mechanical and electric paths, limiting the use of the path with better transmission efficiency.
Innovation Solution
A control device for a vehicle drive device that includes a hydraulic power transmission device, a first electric motor coupled to the input-side rotating element, and a second electric motor coupled to the drive wheels, with an electric path for power transmission and a mechanical path, allowing the engine operating point to be controlled by adjusting the torque of the first electric motor, and a capacity variable device to adjust the hydraulic power transmission device's capacity, thereby optimizing torque distribution between paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operating point is controlled by adjusting the torque of the first electric motor, then the engine can operate at an optimal point for fuel efficiency, but the torque transmitted to the mechanical path side is uniquely determined by the hydraulic characteristic of the hydraulic power transmission device, limiting the proportion of power transmission through the path with better transmission efficiency
Solution Approach 1:
The patent introduces a capacity variable device that can dynamically adjust the capacity of the hydraulic power transmission device. This allows the system to change its hydraulic characteristics in real-time, enabling flexible torque distribution between the mechanical and electric paths while maintaining optimal engine operating points for fuel efficiency.
Solution Approach 2:
The patent changes the capacity parameter of the hydraulic power transmission device to alter its hydraulic characteristics. By adjusting this parameter, the system can modify the torque transmission properties of the mechanical path, thereby controlling the proportion of power transmitted through each path to optimize overall fuel efficiency.
2Loss of energy
If the capacity of the hydraulic power transmission device is fixed by hardware configuration, then the hydraulic characteristic is uniquely determined, but the proportion of power transmission through the path with better transmission efficiency cannot be sufficiently increased
Solution Approach 1:
The patent transforms the fixed hydraulic system into a dynamic one by introducing a capacity variable device. This device can adjust the capacity of the hydraulic power transmission device during operation, allowing the system to adapt torque distribution to maximize power transmission efficiency through the most efficient path.
Solution Approach 2:
The capacity variable device enables the hydraulic power transmission device to serve multiple functions: it can operate with different capacity settings to accommodate varying transmission efficiency requirements, making the system more versatile in optimizing power transmission through different paths based on operating conditions.
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
This solution enables the vehicle drive device to improve fuel efficiency by adjusting the engine operating point to maximize power transmission through the path with better efficiency, enhancing overall fuel efficiency by balancing torque distribution between the mechanical and electric paths.
Implementation Method 1
a hydraulic power transmission device having an input-side rotating element to which power from an engine is input and an output-side rotating element outputting power to drive wheels
Implementation Method 2
a first electric motor disposed such that power can be transmitted to an input-side rotating element of a hydraulic power transmission device
Implementation Method 3
a second electric motor disposed such that power can be transmitted to drive wheels
Data Source
AI summary
A control device of a vehicle drive device comprises a hydraulic power transmission device having an input-side rotating element to which power from an engine is input and an output-side rotating element outputting power to drive wheels, a first electric motor directly or indirectly coupled to the input-side rotating element, and a second electric motor directly or indirectly coupled to the drive wheels, the vehicle drive device further comprising an electric path through which power is electrically transmitted by giving/receiving electric power between the first electric motor and the second electric motor and a mechanical path through which power is mechanically transmitted via the hydraulic power transmission device, the control device of the vehicle drive device being configured to control an operating point of the engine by adjusting a torque of the first electric motor, the control device being configured to adjust the torque of the first electric motor such that a sum of an engine torque and the torque of the first electric motor is balanced with an input-side load torque generated in the input-side rotating element depending on a speed ratio of the hydraulic power transmission device when the operating point of the engine is controlled, the control device being configured to calculate the input-side load torque based on engine rotation speed indicated by the target engine operating point and determine the torque of the first electric motor based on the engine torque indicated by the target engine operating point and the input-side load torque, the vehicle drive device further comprising a capacity variable device varying a characteristic of a capacity coefficient of the hydraulic power transmission device relative to a speed ratio of the hydraulic power transmission device that is a hydraulic characteristic of the hydraulic power transmission device for determining the input-side load torque.