Hybrid Vehicle Torque Estimation with Variable Retardation
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Solution Overview
Problem
Existing driving torque control devices for hybrid vehicles face challenges in achieving accurate engine torque estimation, particularly due to low estimation accuracy when compensating for retardation, which affects the control of vehicle driving torque and the switching between electric vehicle and hybrid electric vehicle modes.
Innovation Solution
A driving torque control device for hybrid vehicles that includes an engine torque estimation unit compensating for retardation using a delay filter and a retardation factor selection unit, which switches between increase-side and decrease-side retardation factors based on the difference between the engine torque estimation value and instruction value, improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple retardation compensation method is used for engine torque estimation, then the control scheme is simple, but the estimation accuracy is low
Solution Approach 1:
The patent applies dynamics by making the retardation factor variable rather than fixed. The retardation factor changes dynamically based on engine operating conditions including rotational speed, torque change amount from initial torque, and torque fluctuation. This allows the estimation system to adapt to different operational states, improving accuracy without requiring an overly complex control scheme.
Solution Approach 2:
The patent implements parameter changes by adjusting the retardation factor according to multiple parameters: engine rotational speed, torque change amount from initial torque, and torque fluctuation. By changing the retardation factor based on these varying parameters, the system achieves higher estimation accuracy across different operating conditions while maintaining reasonable control complexity.
2Measurement precision
If multiple sensors are used for engine torque estimation, then the estimation accuracy improves, but the device complexity and development processes increase
Solution Approach 1:
The patent replaces the mechanical/sensor-based torque estimation approach with a computational method. Instead of relying on multiple physical sensors (cylinder pressure sensors, advanced torque sensors), the system uses a microprocessor to calculate engine torque based on data from existing sensors (throttle position, rotational speed, intake air amount). This substitution reduces device complexity while maintaining or improving estimation accuracy through sophisticated algorithms.
Solution Approach 2:
The patent creates a virtual model of engine torque behavior through computational estimation. Rather than directly measuring torque with complex sensor systems, the system copies the torque characteristics by calculating them from related parameters (throttle opening, rotational speed, intake air) using predetermined maps and real-time computations. This virtual copying approach avoids the need for complex physical measurement systems.
3Ease of operation
If a fixed retardation factor is used in the delay filter, then the control is simple, but the estimation accuracy changes with rotational speed and torque conditions
Solution Approach 1:
The patent applies dynamics by transitioning from a static, fixed retardation factor to a dynamic, variable retardation factor. The retardation factor now responds to changing engine conditions including rotational speed, torque change amount, and torque fluctuation. This dynamic adjustment maintains control simplicity while significantly improving estimation accuracy across varying operational conditions.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing retardation factor values in a lookup table or map structure. The microprocessor retrieves the appropriate retardation factor based on current operating conditions rather than calculating it in real-time from scratch. This preliminary preparation maintains control simplicity while enabling accurate adaptation to different rotational speed and torque conditions.
Data Source
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AI summary
A driving torque control device for a hybrid vehicle has an engine torque estimation unit configured to estimate an engine torque by compensating for a retardation caused by a delay filter in an engine torque instruction value, and a retardation factor selection unit configured to select, as a retardation factor indicating a retardation degree of the delay filter, any one of an increase-side retardation factor for a case where the engine torque instruction value increases and a decrease-side retardation factor for a case where the engine torque instruction value decreases. The retardation factor selection unit performs switching between the increase-side retardation factor and the decrease-side retardation factor in a case where a difference between the engine torque estimation value and the engine torque instruction value as a filter input value is equal to or smaller than a predetermined value.