Work Machine Engine Speed Control via CVT Ratios
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Solution Overview
Problem
Existing processes for determining the setpoint rotational speed of a prime mover in work machines with continuously variable transmission and power hydraulics are inefficient and not fully suitable for various vehicle systems, especially when sensors for the operating state of the power hydraulics are unavailable or malfunctioning.
Innovation Solution
A process that determines the setpoint rotational speed based on basic, low, and high engine speed settings, considering the operating state of the power hydraulics and continuously variable transmission, allowing adaptation to different vehicle systems and operating conditions without relying on current sensor data, and adjusts engine speed to optimize productivity and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a look-up table with scaling values is used to determine setpoint rotational speed based on boom angle and throttle position, then the rotational speed can be adjusted for different operating conditions, but the process becomes complex and time-consuming
Solution Approach 1:
The patent changes the approach from using a complex look-up table with multiple scaling values to a simplified parameter-based calculation. The control unit directly calculates the setpoint rotational speed using a formula that incorporates the actual transmission ratio, reciprocal transmission range, and engine speed settings, eliminating the need for complex table lookups and scaling operations.
Solution Approach 2:
The patent extracts the essential parameters needed for speed control (actual transmission ratio, reciprocal transmission range, engine speed settings) and removes unnecessary complexity. By taking out only the critical elements and discarding the complex look-up table structure, the system achieves the same adaptability with much simpler processing.
2Productivity
If sensor data for the operating state of power hydraulics is used to determine setpoint rotational speed, then the control can be optimized for current operating conditions, but the system becomes unreliable when sensors fail or are unavailable
Solution Approach 1:
The system uses parameters that are inherently available from the transmission control unit (actual transmission ratio, reciprocal transmission range) rather than relying on external sensors. The control unit serves itself by using its own operational data to determine the setpoint rotational speed, making the system self-sufficient and reliable even when external sensors fail.
Solution Approach 2:
The patent introduces an intermediary calculation method that uses the actual transmission ratio and reciprocal transmission range as mediators between the transmission system and the engine control. These intermediary parameters are reliably available from the transmission control unit and provide a stable basis for determining engine speed without direct dependency on hydraulic sensors.
3Ease of manufacture
If the setpoint rotational speed is determined solely as a function of basic engine speed setting, then the system is simple to implement, but productivity is reduced when high engine speed settings are needed
Solution Approach 1:
The patent makes the engine speed determination dynamic by introducing multiple engine speed settings (low, basic, high) that can be selected based on operating conditions. The control unit dynamically adjusts which speed setting is used and applies appropriate scaling factors, allowing the system to maintain simplicity in implementation while achieving high productivity when needed through dynamic adaptation.
Data Source
AI summary
A process for determining a setpoint rotational speed of a work machine engine, having a continuously variable transmission, based on operation of power hydraulics. The setpoint rotational speed for highly productive operation is determined, without knowledge current operation of the power hydraulics, by a basic engine speed setting. With knowledge of the current operating state, the setpoint rotational speed is determined by the basic speed settings and low or high engine speed settings. The low speed setting alone determines setpoint rotational speeds that are lower than the basic speed setting or a combination of the low and basic speed settings. The high speed setting alone determines setpoint rotational speeds that are higher than the basic speed setting or a combination of the basic and high speed settings. The speed settings can comprise a setpoint rotational speed range of above a reciprocal transmission range of the variable transmission.