Switchable Vacuum Pump Coupling for Brake System
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Solution Overview
Problem
Existing motor vehicle systems with mechanical vacuum pumps require complex constructions and high forces to switch the friction clutch, leading to increased wear and energy consumption due to frequent operation of the vacuum pump for pneumatic power brake units.
Innovation Solution
A hydraulically switchable coupling arrangement between the vacuum pump and internal combustion engine, utilizing a positive-displacement pump rotor, hydraulic control connection, and a switchable control valve with a pneumatic actuator to lock or unlock the coupling, reducing the need for additional pressure sources and simplifying the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a friction clutch is used to couple the pump rotor with the coupling element, then the vacuum pump can be switched on and off, but relatively high forces are required to open or close the clutch and another pressure source must be available for switching
Solution Approach 1:
The patent replaces the friction clutch with a positive-displacement pump rotor that is directly coupled to the coupling element. The switching is achieved through a control valve that directs hydraulic or pneumatic pressure to a diaphragm or piston mechanism, which engages or disengages the pump rotor from the coupling element. This eliminates the need for high-force friction clutch actuation and removes the requirement for a separate pressure source, as the vehicle's existing hydraulic or pneumatic system is utilized.
Solution Approach 2:
The patent introduces a control valve and diaphragm/piston mechanism as intermediary components between the pressure source and the pump rotor coupling. This intermediary mechanism translates controlled pressure application into mechanical engagement or disengagement of the pump rotor, providing precise and low-force switching operation while utilizing the vehicle's existing hydraulic or pneumatic pressure system.
2Reliability
If the vacuum pump is frequently operated to supply the power brake unit, then the braking function is maintained, but wear and energy consumption of the drive increase
Solution Approach 1:
The patent implements a dynamically switchable coupling mechanism that allows the pump rotor to be selectively engaged or disengaged from the coupling element based on braking system requirements. The control valve responds to pressure signals from the power brake unit, automatically engaging the pump only when vacuum is needed for braking operation. This dynamic switching eliminates continuous operation and reduces wear and energy consumption while maintaining reliable braking function.
3Ease of operation
If a friction clutch with pneumatic actuator is used for switching, then the coupling can be controlled, but the construction becomes relatively complex
Solution Approach 1:
The patent merges the coupling mechanism and switching function into a single integrated positive-displacement pump rotor design. The control valve and diaphragm/piston mechanism are combined with the pump rotor assembly, eliminating the need for a separate friction clutch and its pneumatic actuator. This integration simplifies the construction while maintaining controlled coupling functionality, as the same mechanism that drives the pump rotor also provides the switching capability through pressure-actuated engagement or disengagement.
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 provides a reliable, fail-safe mechanism that minimizes wear and energy consumption by using hydraulic pressure to switch the coupling arrangement, allowing for efficient operation of the vacuum pump and reducing the complexity of the system while maintaining high torque transfer reliability.
Implementation Method 1
The switchable control valve is configured, in its unlocked state, to switch the control pressure of the hydraulic fluid through to the hydraulic control connection so as to unlock. The switchable control valve comprises a pneumatic actuator configured to be acted on by a pressure of the negative pressure chamber and to switch the control pressure through to the hydraulic control connection
Implementation Method 2
The vacuum pump comprises a positive-displacement pump rotor, a coupling element configured to be mechanically driven by an internal combustion engine
Data Source
AI summary
An arrangement of motor vehicle units includes a vacuum pump, a power brake unit, a pump which pumps a hydraulic fluid with a control pressure, and a control valve. The vacuum pump comprises a pump rotor, a coupling element, a control connection, a coupling arrangement switchable by the control connection to lock/unlock the coupling element with the pump rotor, and a suction connection. The power brake unit comprises a negative pressure chamber connected with the suction connection. The control valve, when unlocked, switches the control pressure of the hydraulic fluid through to the control connection to unlock. The control valve comprises an actuator acted on by a pressure of the negative pressure chamber which switches the control pressure through to the control connection if the pressure in the negative pressure chamber is greater than a threshold pressure so that the switchable control valve is switched into its unlocked state.