Variable Speed Pump Driveline Clutch Actuation
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Solution Overview
Problem
Limited-slip driveline clutches in differentials often require expensive systems with pumps and accumulators, and fixed orifices, which increase installation and operational costs, while existing systems can lead to traction loss in vehicles due to uncontrolled differential rotation.
Innovation Solution
A hydraulic pump operated by a variable speed drive generates hydraulic flow in a circuit with a flow regulating valve to control clutch actuation, preventing excessive fluid flow rates regardless of pressure, and an electronic control system adjusts pump speed to maintain the hydraulic circuit within a transition region, optimizing energy use and reducing the need for additional costly components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulically actuated clutch with pump and accumulator is used to limit differential rotation, then traction control is improved, but device complexity and installation cost increase
Solution Approach 1:
The patent removes the accumulator component from the traditional hydraulic system, using only the pump and control valve to achieve limited-slip functionality. This extraction of the accumulator simplifies the system while maintaining traction control through the variable speed pump and flow regulating valve combination.
Solution Approach 2:
The hydraulic pump serves multiple functions: it provides actuation pressure for the clutch, regulates flow to control slip characteristics, and its variable speed capability allows dynamic adaptation to different operating conditions. This multi-functionality reduces the need for separate components like accumulators.
2Ease of manufacture
If fixed orifices are used in the hydraulic circuit, then flow control is simplified, but energy loss increases due to higher output levels
Solution Approach 1:
The patent replaces fixed orifices with a variable speed pump and flow regulating valve system that dynamically adjusts hydraulic flow based on actual operating conditions. This dynamic control allows the system to use only the necessary flow rate, avoiding the continuous high output and associated energy losses of fixed orifice systems.
Solution Approach 2:
The system changes the flow rate parameter dynamically through variable speed pump control and flow regulating valve adjustment, rather than relying on fixed orifice geometry. This allows optimization of energy consumption by matching flow output to actual demand while maintaining simple circuit design.
3Reliability
If pump operates at higher output levels to ensure sufficient flow, then clutch actuation reliability is improved, but energy consumption increases
Solution Approach 1:
The patent employs a control system that monitors clutch engagement status and differential slip conditions, then adjusts pump speed accordingly. This feedback control ensures the pump operates at the minimum necessary output level to maintain reliable clutch actuation, avoiding continuous high-energy operation while preserving actuation reliability.
Solution Approach 2:
The variable speed pump operates periodically at higher output levels only when clutch actuation is required, then reduces to lower output levels during normal operation. This periodic high-output action maintains reliability when needed while minimizing overall energy consumption during sustained operation.
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 effectively limits relative rotation between driveline components without additional expensive equipment, enhancing traction control and reducing energy consumption by optimizing pump operation within specific pressure and flow rate conditions.
Implementation Method 1
A hydraulic pump operated by a variable speed drive may be included in the hydraulic circuit and configured to generate hydraulic flow
Implementation Method 2
A flow regulating valve may be included in the hydraulic circuit and configured to regulate a hydraulic fluid flow rate through the hydraulic circuit
Implementation Method 3
A variable speed drive may be included having an output coupled to the hydraulic pump and configured to control a rotational speed of the hydraulic pump
Data Source
AI summary
The present disclosure relates to a limited-slip clutch system and method. In one aspect, the limited-slip clutch actuation system can include a hydraulic pump operated by a variable speed drive wherein the pump can be configured to generate hydraulic flow in a hydraulic circuit including an actuation branch line that actuates a clutch. The circuit may also include a flow regulating valve for regulating a hydraulic fluid flow rate through the hydraulic circuit wherein the flow regulating valve can be configured to prevent the hydraulic fluid flow rate from exceeding a set maximum flow rate regardless of a magnitude of the hydraulic pressure in the hydraulic circuit. In operation, the pump speed can be controlled based on a command pressure set point and the measured pressure in the actuation branch line and to minimize operational costs by operating the pump at a transition region of the system pressure-pump speed curve.