Automotive Coolant Pump Wet Friction Clutch Drag Reduction
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Solution Overview
Problem
Existing mechanical switchable automotive coolant pumps with wet friction clutches experience significant drag moment when disengaged, leading to unnecessary pump performance even when cooling is not required.
Innovation Solution
A mechanical switchable automotive coolant pump with an electromagnetic wet friction clutch arrangement featuring a static pump frame, a rotatable rotor shaft, a pulley wheel, and a pump wheel with separate stop friction surfaces, which are engaged by an electromagnet to completely stop the pump wheel rotation when disengaged, ensuring zero coolant flow when cooling is not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wet friction clutch is used in the coolant pump, then the clutch can be engaged and disengaged to control coolant flow, but significant drag moment is transferred when disengaged causing unnecessary pump performance
Solution Approach 1:
A friction element is introduced as an intermediary between the pump wheel and the drive mechanism. This friction element can be selectively engaged or disengaged via an electromagnet, allowing complete separation when disengaged to eliminate drag moment, while enabling controlled engagement to regulate coolant flow. The friction element acts as a mediator that decouples the pump wheel from the drive when cooling is not required.
2Ease of operation
If the clutch disk rotates with the rotor shaft when disengaged, then the clutch can be easily disengaged, but the rotating clutch disk rotates the coolant liquid which generates drag torque on the pump wheel
Solution Approach 1:
The clutch system is segmented into separate functional elements: a clutch disk connected to the rotor shaft, a friction element that can be independently engaged or disengaged, and a pump wheel. This segmentation allows the clutch disk to remain rotationally free when disengaged while the friction element is positioned to prevent contact with the pump wheel, eliminating the coupling between disk rotation and pump wheel rotation that causes unwanted pump performance.
3Loss of energy
If a separate stop friction surface is added to stop the pump wheel, then the pump wheel can be completely stopped when disengaged, but the device complexity increases
Solution Approach 1:
The stop friction function is merged with the existing friction element and clutch disk. The friction element serves dual purposes: it provides friction engagement for clutch operation and simultaneously acts as a stop element against the clutch disk's stop friction surface. This merging eliminates the need for separate stop mechanisms, reducing device complexity while achieving complete pump wheel stopping when disengaged.
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
The solution effectively reduces pump performance to zero when cooling is not required, preventing unnecessary engine cooling and improving efficiency by ensuring the pump wheel stops rotation when the clutch is fully disengaged, thus conserving energy and reducing drag moment.
Implementation Method 1
The friction clutch can be actuated by an electromagnet which attracts at least one clutch element when the electromagnet is electrically energized
Implementation Method 2
a sufficient braking torque is generated which completely stops the rotation of the pump wheel when the wet friction clutch is in the fully disengaged state
Implementation Method 3
a significant drag moment is transferred by a wet friction clutch in the disengaged clutch state
Data Source
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AI summary
The invention refers to a mechanical switchable automotive coolant pump (10) for providing a liquid coolant for an automotive engine (12). The pump comprises a static pump frame (30), a rotatable rotor shaft (20) which is rotatably supported at the pump frame (30), a pulley wheel (22) which is co-rotatably fixed to the rotor shaft (20) and which suitable to be mechanically driven by the engine (12), a rotatable and axially shiftable pump wheel (60) which is rotatably supported and is axially shiftable with respect to the rotor shaft (20) and to the pump frame (30) and which Is provided with a ferromagnetic means, and an electromagnetic wet friction clutch arrangement (50) with a static electromagnet (32) and a clutch disk (51) which is co-rotatably supported by the rotor shaft (20), a clutch friction surface (54) at the clutch disk (51) and a corresponding clutch friction surface (62) at the pump wheel (16), and a separate stop friction surface (64) at the pump wheel (60) and a corresponding static stop friction surface (36) at the pump frame (30). The pump wheel (60) is axially attracted by the excited electromagnet (52) so that the stop friction surfaces (64, 36) engage and the pump wheel (60) is stopped.