Engine Vacuum Generation via Transmission Neutral Shifting
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Solution Overview
Problem
Small displacement engines face difficulties in producing sufficient intake manifold vacuum, especially at higher altitudes and during conditions of repeated brake pedal use, leading to potential hard brake pedal feel and inadequate vacuum for vehicle systems.
Innovation Solution
Shifting the transmission into neutral in response to a predetermined number of braking events, reducing engine load and increasing vacuum production by lowering intake manifold pressure, thereby enhancing vacuum availability for vehicle systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a smaller displacement engine is used to reduce pumping losses and friction, then fuel efficiency is improved, but the engine's ability to produce sufficient intake manifold vacuum deteriorates
Solution Approach 1:
The system dynamically shifts the transmission between gear and neutral states based on real-time monitoring of braking events. When repeated braking is detected, the transmission shifts to neutral to increase engine vacuum production for the brake booster, then returns to gear when braking stops. This dynamic adaptation allows the smaller engine to maintain sufficient vacuum under varying operating conditions without compromising fuel efficiency during normal operation.
Solution Approach 2:
The system changes the operational parameters of the engine by altering the transmission state. Shifting to neutral changes the engine load and intake manifold pressure conditions, thereby increasing vacuum production. This parameter change enables the engine to provide adequate vacuum for the brake booster during repeated braking events while maintaining fuel efficiency during normal driving.
2Reliability
If the transmission is shifted into neutral to increase engine vacuum production, then vacuum availability for brake systems is improved, but vehicle acceleration response deteriorates
Solution Approach 1:
The system employs periodic shifting to neutral only during specific conditions (repeated braking events), rather than maintaining neutral continuously. The controller monitors braking events and shifts to neutral temporarily when needed, then returns to gear when braking ceases. This periodic application ensures vacuum is available when required for brake operation while minimizing the impact on acceleration response during normal driving.
Solution Approach 2:
The transmission state is dynamically adjusted based on real-time braking event detection. The system shifts to neutral only during repeated braking conditions and returns to gear when braking stops, creating a dynamic response that balances vacuum production needs with acceleration performance requirements.
3Reliability
If neutral idle is used frequently to improve brake booster vacuum, then vacuum production is enhanced, but fuel consumption increases
Solution Approach 1:
The system applies neutral idle only partially and selectively during repeated braking events rather than continuously. The controller monitors braking patterns and activates neutral idle mode only when the threshold for repeated braking is exceeded, providing just enough vacuum enhancement when needed while avoiding unnecessary fuel consumption during normal operation.
Solution Approach 2:
The system uses feedback from the brake pedal sensor to detect repeated braking events and automatically activates neutral idle mode when needed. The controller continuously monitors braking patterns and adjusts transmission state accordingly, ensuring vacuum production is enhanced only when actually required for brake operation, thereby minimizing fuel consumption impact.
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 approach improves the operation of vacuum-operated systems, reduces the likelihood of hard brake pedal feel, and maintains driver satisfaction by providing additional vacuum when needed, without significantly increasing fuel consumption.
Implementation Method 1
shifting a transmission coupled to an engine into neutral from a forward or reverse gear, load on the engine may be reduced so that engine intake manifold pressure may be reduced
Data Source
AI summary
Methods and systems for improving vacuum generation for an engine that may be operated at higher altitudes are presented. In one non-limiting example, a transmission that is mechanically coupled to the engine may be shifted from a gear to neutral in response to an actual total number of times a vehicle brake pedal is applied and partially released while the vehicle is stopped and the brake pedal is applied.