IPGATE AG – Patent Family E142 · SMBS Self-Monitoring Braking System

E142 – SMBS Self-Monitoring
Braking System

Automatic leak and valve diagnosis turning electrohydraulic brake systems into self-monitoring systems. 7 independent inventions · 6 property rights · US · CN · DE

E142 – Why fail-operational? Evolutionary stages of fault tolerance
Applicant IPGATE AG, Churerstrasse 160a, 8808 Pfäffikon (CH)
Inventors Heinz Leiber, Dr. Anton van Zanten
Priority / Filing Date April 21, 2015 (DE 10 2015 106 089.2)
PCT Application None — national applications (US, CN, DE)
Technology SMBS – Self-Monitoring Brake System with automatic leak and valve diagnosis (three-stage: BED / CSD / PSD)
Innovations 7 independent inventions (3 granted: US, CN, CN1 · 3 pending: DE, DE1, DE2)
6
Property Rights
3
Jurisdictions
7
Independent Inventions
2015
Priority
IBS3 / B2
Technology Basis

Self-Monitoring Brake System —
Three-Stage Automatic Diagnosis

Patent family E142 describes the SMBS — a diagnostic procedure that turns electrohydraulic brake systems into self-monitoring systems. After each braking operation, seals and solenoid valves are automatically checked in software alone, without additional hardware, at pressures of typically 5 to 25 bar.

The SMBS performs diagnosis in three complementary modes that differ in test frequency, pressure level, and test depth. Together they form a multi-stage fault detection cascade — the probability of an undetected safety-relevant fault drops to 10⁻⁸ to 10⁻¹⁰ per year, a prerequisite for fail-operational braking systems in autonomous driving at SAE levels 3 to 5.

The SMBS concepts were first validated publicly at the VDI Knowledge Forum on October 25, 2017 (Leiber, Köglsperger, Hecker: "X-Boost and IBS-Gen3 – Diagnostic Concepts for Fail-Operational Brake Systems") and were rated as groundbreaking by industry experts. The basic principles are now an integral part of modern one-box braking systems, confirmed by IPGATE licensees including a leading European Tier 1 supplier with significant market share in integrated braking systems.

E142 – Why fail-operational? Evolutionary stages of fault tolerance
Figure 1 — Why fail-operational? Evolutionary stages of fault tolerance · VDI Wissensforum 2017 · IPGATE AG
BED — Brake End Diagnosis
During travel · v > 0 · ~5 bar / ~0.2 s
Performed at the end of each braking operation while the vehicle is still moving. A low pressure of approx. 5 bar is held for approx. 0.2 s and the brake circuits are checked for tightness. Very high test frequency — every braking event — reduces the probability of failure by several orders of magnitude.
Test A — BK1 / BK2
CSD — Complete Stop Diagnosis
Standstill · v = 0 · 10–20 bar · ~10× per hour
Performed when the vehicle is stationary, statistically approx. 10 times per hour of braking operation. Uses the residual pressure remaining after braking for an extended test sequence covering brake circuits, auxiliary piston circuit, DAP seals, and all closed valves (MV/RV1, VF, AV).
Test A — Brake circuits Test B — Aux. piston Test D — DAP seals
PSD — Parking Stop Diagnosis
Parked · up to 100 bar · unlimited · ~1× per hour
Performed when parking, statistically about once per hour of driving time. Without time limits, extended tests at up to 100 bar check check valve–throttle combinations and the second auxiliary piston seal not covered by CSD — completing a full leak test of all valves and seals.
Tests A–D — All components Test C — Pedal travel
US CN DE

Dormant Faults — The Core Problem

The most critical weakness of electrohydraulic braking systems are dormant faults: latent leaks in seals and solenoid valves caused by wear or contamination that remain undetected until an actual braking event where they may cause failure.

A conventional pre-drive check (PDC) detects such faults in principle, but puts additional pressure cycles on the components and in extreme cases doubles the stress cycles on the seals. For a brake system with approximately 200,000 actuations per year and up to 15 valves per system, this is a significant disadvantage in terms of service life. For fail-operational brake systems — mandatory from SAE Level 3 (HAD) onwards — seamless diagnosis of all safety-relevant components without additional stress is of crucial importance.

E142 – Dormant faults: the core problem with approx. 15 valves per system
Figure 2 — Dormant faults: the core problem with approx. 15 valves per system · VDI Wissensforum 2017 · IPGATE AG
Prior Art Limitation: Conventional PDC-based diagnostics apply dedicated pressure cycles purely for testing purposes, doubling seal stress cycles. With up to 15 valves per system and 200,000 actuations/year, this significantly reduces service life. No conventional system achieves test frequencies sufficient for fail-operational SAE L3–5 requirements.
SMBS Solution: Three-stage cascade (BED after every braking event · CSD ~10×/hour · PSD ~1×/hour) uses only naturally occurring residual pressure — no additional hardware, no extra stress cycles. Combined failure probability: 10⁻⁸ to 10⁻¹⁰ per year.

Three Diagnostic Levels

The combination of the three diagnostic stages with different test depths and test frequencies — BED (highest frequency / lowest depth) through PSD (lowest frequency / greatest depth) — creates a cascading fault detection architecture. With approximately 200,000 braking operations per year, the BED achieves an average fault detection time of less than one minute. The CSD checks the auxiliary piston and valve circuits approximately 10 times per hour of braking operation. The PSD completes the diagnosis during parking with high-pressure tests of all remaining components.

E142 – Three diagnostic levels D1–D2–D3 – Smart diagnosis D3 as core innovation
Figure 3 — Three diagnostic levels D1–D2–D3 · Smart diagnosis D3 as core innovation E142 · VDI Wissensforum 2017 · IPGATE AG

Four Test Types

Test A — Brake Circuit Leak Detection: Checks brake circuits BK1 and BK2 for leaks via pressure curve evaluation over a defined hold time. Performed in all three diagnostic modes.
Test B — Auxiliary Piston Circuit: Checks the auxiliary piston circuit via targeted solenoid valve control (open ESV, close WA). Performed in CSD and PSD modes.
Test C — Displacement-Based Diagnosis: Uses pedal travel sensor (slave) in pressureless brake circuits for displacement-based leak detection — an independent measurement channel not relying on pressure sensors. Performed in PSD mode.
Test D — DAP Seal Monitoring: Monitors double-acting piston (DAP) tightness via piston position monitoring during pressure hold phases. Performed in CSD and PSD modes.

7 Independent Inventions across 6 Property Rights

Three groups: the broad SMBS framework (US · CN · DE master), BED-specific innovations (CN1 · DE2-A1), and device plus system-level protection (DE1 · DE2-A6).

SMBS Framework — Broad Method Protection · US · CN · DE
E142US · Claim A
SMBS Basic Method
US 10,059,321 B2 · Granted
Automatic diagnosis of seal and valve function after braking using low residual pressure. Covers all three diagnostic modes (BED/CSD/PSD) and the four test types (A–D). Primary commercial protection right — broadest English-language protection for the SMBS framework.
E142CN · Claim A
SMBS Basic Method (CN)
CN 107472232 B · Granted
Chinese equivalent of the SMBS basic method. Diagnostic methodology identical to US and DE — automatic leakage and valve diagnosis after braking at low residual pressure across all three diagnostic modes. Protects the SMBS framework in the Chinese market.
E142DE · Claim A1
SMBS Master Application (DE)
DE 102015106089 · Pending
Master German application with the broadest SMBS protection scope — all diagnostic modes, all four test types, all delivery device variants. Basis for divisional applications DE1 and DE2. Widest claim breadth within the German national filing strategy.
BED Innovations — On-Drive Diagnosis · CN1 · DE2-A1
E142CN1 · Claim A1
BED Threshold-Based On-Drive Diagnosis
CN 113771822 B · Granted
On-drive self-diagnosis: threshold-based leakage detection at v > 0 during the final phase of a braking operation. CN-specific divisional targeting the highest-frequency diagnostic mode — detects pressure drop exceeding defined threshold values within the ~0.2 s hold window.
E142DE2 · Claim A
BED Holding Pressure Specification
DE · Pending
BED specification claim: defines the diagnosis at brake end with specific operating parameters — holding pressure (~5 bar), duration (~0.2 s), and vehicle speed condition (v > 0). Protects the precise BED parameter window that enables diagnosis without driver awareness or additional pressure generation.
Device & System-Level Protection · DE1 · DE2-A6
E142DE1 · Claim A1
Auxiliary Piston Seal Architecture
DE 102015017422 · Pending
Device claim: auxiliary piston seal architecture with dedicated leak flow channel. Structural protection for the hardware configuration enabling Test B (auxiliary piston circuit diagnosis). The leak flow channel provides a defined, measurable path for pressure loss quantification during CSD mode — independent of the method claims.
E142DE2 · Claim A6
SMBS Test Sequence T1–T4
DE · Pending
Higher-level self-monitoring program: systematic test sequence T1–T4 that orchestrates the complete SMBS diagnostic cycle — scheduling BED, CSD, and PSD across all four test types in a defined execution order. System-level method protection for the overall SMBS program logic.
Section 1 · Invention Overview

Diagnostic Modes, Descriptions & Keywords

All 7 independent inventions with diagnostic mode assignment. The BED / CSD / PSD column indicates the primary diagnostic mode addressed by each claim.

Property Right Claim Mode Type Description Keyword
SMBS Framework — US · CN · DE
E142US
US 10,059,321 B2		 A BED/CSD/PSD Method SMBS basic method: automatic diagnosis of seal and valve functions after braking at low residual pressure. Covers all three diagnostic modes and four test types (A–D). SMBS basic method
E142CN
CN 107472232 B		 A BED/CSD/PSD Method Chinese equivalent: diagnostic methodology identical to US/DE — automatic leakage and valve diagnosis after braking using low residual pressure across all three diagnostic modes. SMBS basic method (CN)
E142DE
DE 102015106089		 A1 BED/CSD/PSD Method Master DE application with the broadest SMBS protection scope: all diagnostic modes, all test types, all delivery device variants. Basis for divisional applications DE1 and DE2. SMBS master (DE)
BED Innovations — CN1 · DE2-A1
E142CN1
CN 113771822 B		 A1 BED Method On-drive self-diagnosis at v > 0: threshold-based leakage detection during the final phase of braking. CN-specific divisional targeting the highest-frequency diagnostic mode. BED threshold diagnosis
E142DE2 A BED Method BED specification: diagnosis at brake end with defined operating parameters — holding pressure (~5 bar), duration (~0.2 s), speed condition v > 0. BED holding pressure
Device & System-Level — DE1 · DE2-A6
E142DE1
DE 102015017422		 A1 CSD/PSD Device Auxiliary piston seal architecture with dedicated leak flow channel. Structural hardware protection enabling Test B (auxiliary piston circuit diagnosis via defined pressure loss path). Auxiliary piston leak channel
E142DE2 A6 BED/CSD/PSD Method Higher-level self-monitoring program: systematic test sequence T1–T4 orchestrating the complete SMBS diagnostic cycle — scheduling all three modes and four test types in a defined execution order. SMBS test sequence T1–T4
Section 1a · Family Overview

Jurisdictions & Status

All 6 property rights of the E142 patent family as of February 2026. Three granted patents (US, CN, CN1 divisional); three DE applications pending. Priority date: April 21, 2015.

File No. Country Status Type Application No. Filed Grant No. Granted
E142CN CN Granted Patent 201610404808.5 Jun. 8, 2016 CN107472232B Sep. 14, 2021
E142US US Granted Patent 15/133,459 Apr. 20, 2016 US10,059,321 B2 Aug. 28, 2018
E142CN1 CN Granted Patent (divisional) 202110973583.6 Jun. 8, 2016 CN113771822B Mar. 8, 2024
E142DE DE Pending Patent 102015106089.2 Apr. 21, 2015 – –
E142DE1 DE Pending Patent (divisional) 102015017422.3 – – –
E142DE2 DE Pending Patent (divisional) – – – –
US CN DE