Hydraulic Braking Torque Control in Electric Compaction Machines
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Solution Overview
Problem
Compaction machines powered by electric motors face challenges in generating reliable braking torque, leading to potential hazards and safety risks due to reduced support torque, high overspeeds, and overheating during braking, especially when switching from combustion engines.
Innovation Solution
A method and compaction machine using an electric motor with a hydraulic system that includes a control device to determine operating parameters, generate braking torque through a hydraulic throttle in a brake hydraulic circuit, and transfer this torque via a mechanical coupling to the drive system, ensuring safe and efficient braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an electric motor is used to replace a combustion engine in a compaction machine, then environmental friendliness and energy efficiency are improved, but the ability to generate reliable support torque for braking is worsened
Solution Approach 1:
The patent introduces a hydraulic system as an intermediary between the electric motor and the braking function. The hydraulic pump converts excess motor speed into hydraulic pressure, which then acts as a mediator to provide reliable braking torque without requiring the electric motor itself to generate the braking force directly. This resolves the contradiction by decoupling the motor's primary function from the braking function.
Solution Approach 2:
The patent employs a hydraulic braking system where the hydraulic pump serves dual purposes: driving the compaction machine and providing braking torque. By utilizing hydraulic pressure generated during braking, the system achieves reliable support torque that is independent of the electric motor's electrical state, thus resolving the reliability issue while maintaining environmental friendliness.
2Speed
If an electric motor with reduced mass moment of inertia is used, then response speed is improved, but high overspeeds occur leading to unsafe operating conditions
Solution Approach 1:
The patent converts the harmful effect of high overspeeds into a useful function. Instead of viewing the electric motor's tendency to overspeed as a problem to be eliminated, the system utilizes this characteristic to drive the hydraulic pump, which then generates braking torque. The overspeed condition becomes the driving force for the hydraulic system, transforming a safety hazard into a functional advantage.
Solution Approach 2:
The hydraulic system acts as an intermediary that buffers and controls the electric motor's speed variations. The hydraulic pump absorbs the motor's overspeed energy and converts it into hydraulic pressure, which then provides controlled braking torque. This intermediary mechanism prevents direct transmission of harmful overspeeds to the compaction machine while maintaining safe operating conditions.
3Speed
If heavy or frequently repeated braking is performed, then deceleration performance is improved, but overheating of the electric motor, inverter, and battery occurs
Solution Approach 1:
The patent extracts the braking function from the electric motor-inverter-battery system and transfers it to a separate hydraulic braking system. By taking out the braking load from the electrical system, the electric motor, inverter, and battery are protected from overheating during heavy or frequent braking operations, while the hydraulic system handles the thermal load independently.
Solution Approach 2:
The hydraulic braking system provides a thermal isolation mechanism. The hydraulic fluid absorbs and dissipates the heat generated during braking independently of the electrical system. This allows heavy or frequent braking to be performed without transferring thermal energy to the electric motor, inverter, or battery, thus preventing overheating while maintaining deceleration performance.
4Ease of operation
If a hydraulic throttle is used to generate braking torque, then braking control flexibility is improved, but energy loss increases
Solution Approach 1:
The patent maintains continuity of useful action by using the hydraulic pump to convert what would otherwise be wasted motor overspeed energy into useful hydraulic pressure for braking. Instead of simply throttling and dissipating energy, the system continuously converts kinetic energy from the motor's inertia into braking torque through the hydraulic circuit, reducing energy loss while maintaining control flexibility.
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
Enables reliable, adjustable, and efficient braking in compaction machines, preventing overheating and maintaining safe operating conditions by generating support torque without relying on combustion engines, thus avoiding hazards and ensuring continuous operation.
Implementation Method 1
generating a braking torque by means of a hydraulic throttle (18) in a brake hydraulic circuit (53), wherein the throttle (18) is arranged in a hydraulic line (25) with a hydraulic pump (13, 54)
Implementation Method 2
transferring the braking torque via a mechanical coupling (11) from the brake hydraulic pump (13, 54) to a device (12) that directly or indirectly drives the driving device (52, 55)
Implementation Method 3
transferring the braking torque via a mechanical coupling (11) from the brake hydraulic pump (13, 54) to a device (12) that directly or indirectly drives the driving device (52, 55)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method (40) for braking a compaction machine (1) operated by means of an electric motor (4). Furthermore, the invention relates to a compaction machine (1), in particular a tandem roller, roller compactor or refuse compactor, for carrying out the method (40).