Brake Shift Interlock Solenoid-Switch Assembly for Park Lock Detection

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Solution Overview

Problem

Current Brake Transmission Shift Interlock (BTSI) systems in motor vehicles rely on electromechanical switches and dedicated hardware, which increase costs, noise, and complexity, and can fail in an unlocked state, posing a severity ten (10) Failure Modes and Effects Analysis (FMEA) system failure.

Innovation Solution

A BTSI system utilizing a resistor ladder circuit and a combination of a shifter solenoid and position switch, where the solenoid mechanically engages or disengages the position switch to detect the locked or unlocked state, eliminating the need for electromechanical switches and reducing hardware requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electromechanical switches and dedicated hardware are used in BTSI systems, then the system can detect locked or unlocked states, but manufacturing costs, design costs, noise, and system complexity increase

Engineering Contradiction:

ImproveBTSI state detection reliabilityVSAvoidhardware complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the BTSI position switch and shifter solenoid into a single integrated assembly where the solenoid directly actuates the switch. This merging eliminates the need for separate dedicated hardware components while maintaining reliable detection of locked/unlocked states through the integrated mechanical-electrical connection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shifter solenoid serves dual functions: it mechanically locks/unlocks the transmission shifter and simultaneously actuates the BTSI position switch to signal the system state. This multi-functionality eliminates the need for separate detection hardware, reducing overall system complexity while maintaining reliable state detection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If electromechanical switches are used in BTSI systems, then the system can detect shifter position, but noise is generated

Engineering Contradiction:

Improveshifter position detectionVSAvoidelectromechanical noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

By integrating the position switch directly into the solenoid assembly, the patent eliminates separate electromechanical switching components that generate noise. The combined design reduces the number of moving parts and electrical contacts, thereby minimizing electromagnetic interference and mechanical noise while maintaining accurate shifter position detection.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If traditional BTSI systems are used, then the transmission can be shifted out of park when brake pedal is depressed, but the system may fail in unlocked state posing severity ten FMEA failure

Engineering Contradiction:

Improveshifter operationVSAvoidsystem safety

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The integrated solenoid-switch assembly provides immediate mechanical feedback that directly correlates the solenoid's locked/unlocked position with the switch's electrical state. This direct mechanical coupling ensures that the system accurately detects and responds to shifter lock status, providing reliable feedback to the control system to prevent unsafe operation and eliminate severity ten FMEA failures.

Inventive Principle:

Principle #23Feedback

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 minimizes manufacturing and design costs, eliminates noise associated with electromechanical switches, and prevents the transmission from being shifted out of park without the brake pedal being depressed, thereby enhancing safety and reliability.

Implementation Method 1

A solenoid is selectively operable to move the solenoid armature between the locked and unlocked positions to thereby block and unblock movement of the gear shifter

Methodology Applied

Scientific EffectSolenoid: Solenoid

Implementation Method 2

a resistor ladder circuit electrically connected to the position switch for detecting a current Brake Transmission Shift Interlock (BTSI) state

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS11326690B2Brake transmission shift interlock systems and control logic for motor vehicle powertrains

Publication Date: 2022.05.10 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Presented are Brake Transmission Shift Interlock (BTSI) systems for vehicle powertrains, methods for making/operating such BTSI systems, and vehicles equipped with a BTSI system. A BTSI system for a motor vehicle includes a shifter solenoid with a solenoid body that mounts to the vehicle body, and a solenoid armature that is movably attached to the solenoid body to transition back-and-forth between locked and unlocked positions. The shifter solenoid is selectively operable via a brake control module to move the solenoid armature between the locked and unlocked positions to thereby block and unblock movement of a gear shifter from the park position, respectively. A position switch mounts to the vehicle body adjacent the shifter solenoid and detects the vehicle transmission being in a park mode. The position switch selectively mechanically engages with the shifter solenoid such that the solenoid armature, upon moving to the locked position, pushes closed the position switch.