E138 – Continuous DAP Delivery &
Area-Switchable DAP Technology
Continuous double-stroke piston delivery technology and area-switchable DAP technology with active pressure reduction. 8 independent inventions · 7 granted rights · EP · DE · FR · KR · CN · US
| Applicant | IPGATE AG, Churerstrasse 160B, 8808 Pfäffikon (CH) |
| Inventors | Heinz Leiber, Anton van Zanten, Christian Köglsperger, Valentin Unterfrauner |
| Priority / Filing Date | May 20, 2015 (DE102014107112); July 4, 2014 (DE102014109384); July 9, 2014 (DE102014109628) |
| PCT Application | PCT/EP2015/061105 |
| Technology | Continuous DHK conveyor technology (E138WO-SA) · Area-switchable DHK technology with active pressure reduction (E138WO-TA1) |
| Innovations | 8 independent invention concepts (SA: EP/CN/KR A1, EP A12, EP A13 | TA1: US/CN A1, US A13, CN A18, CN A19) |
Bidirectional DHK Technology for EHB Systems
Patent family E138 describes an actuation system for vehicle brakes with an electrically driven double-acting piston (DAP) that supplies pressure to the brake circuit in both piston movement directions — providing virtually uninterrupted pressure supply with high dynamics.
The E138 patent family describes an actuation system for vehicle brakes in which a second, electrically driven pressure source with double-acting pistons (DAP) supplies pressure medium to the brake circuit in both piston movement directions in a controlled manner. The family comprises two technological focal points: (1) the basic continuous DAP delivery technology (E138WO-SA) and (2) the advanced area-switchable DAP technology with active pressure reduction (E138WO-TA1).
The E138 patent family comprises 7 property rights in the jurisdictions EP (with validation in DE and FR), US, CN, and KR. The US and CN divisionals (E138WOUS1, E138WOCN1) protect the advanced technology with exactly two solenoid valves connected in series. Alongside the E136 patent family, the EP patent forms the basic patent for bidirectional double-stroke piston technology in electrohydraulic braking systems.
Development History
The development of the E138 technology began in 2014 in parallel with the E136 family and addressed the same fundamental problem: In modern brake-by-wire systems, sufficiently large volumes of pressure medium must be provided for pre-filling, ABS control, and fading situations without interrupting pressure build-up and without compromising fault tolerance.
Previous solutions (e.g., reservoir chamber concepts from DE 10 2011 009059, DE 10 2011 111368) had in common that they either placed high demands on valve tightness, interrupted pressure build-up during long braking processes, or subjected the spindle and ball screw drive to additional axial forces. The basic idea — the use of a double-acting piston (DAP) that delivers controlled pressure medium to the brake circuits during both the forward and return strokes — fundamentally solves the problem of pressure interruption: Since both piston strokes are used for pressure supply, theoretically unlimited volume delivery with high dynamics (switching time <10 ms) is possible without interrupting pressure build-up.
The divisional applications E138WOUS1 and E138WOCN1 extend the basic concept with a precise valve architecture featuring exactly two solenoid valves (AS + VF) connected in series, which enable variable piston area control, active pressure reduction via the DAP, and an innovative diagnostic procedure using volume-pressure correlation.
8 Independent Inventions in Two Groups
Group 1 (E138WO-SA): 3 core innovations for continuous DHK delivery technology. Group 2 (E138WO-TA1): 5 core innovations for area-switchable DHK technology with active pressure reduction.
Categories, Descriptions & Keywords
Overview of all 8 independent invention concepts across two subfamilies. E138WO-SA covers the basic continuous delivery technology; E138WO-TA1 extends with area-switchable operation and active pressure reduction.
| Invention | Cat. | Description | Keyword |
|---|---|---|---|
| E138WO-SA — Continuous DHK Delivery Technology | |||
| E138 A1 (EP, CN, KR) |
Device | Actuating mechanism with pedal-operated first pressure source (HZ) and electromechanically driven DAP. DAP feeds pressure medium into at least one brake circuit in both directions of movement. Virtually uninterrupted pressure supply; significant reduction in dead times. Basic patent for bidirectional DAP technology. Note: "Graduated design" is an optional feature, not mandatory in the scope of protection. | Continuous DAP delivery |
| E138 A12 (EP) |
Method | DHK supplies pressure medium to the rear of the HZ piston; pressure generation in brake circuits without shut-off valves. Operating modes (pre-fill, ABS, max pedal force, travel simulator, fallback) controlled via solenoid valves. Simplified architecture, shorter response times, improved ABS performance. | Isolation-valve-free braking method |
| E138 A13 (EP) |
Device | Actuation system with DAP and single master cylinder (SHZ). DAP compensates for lack of THZ redundancy through bidirectional delivery. Length reduced by up to 50% vs. conventional THZ systems. | DAP-SMC compact architecture |
| E138WO-TA1 — Area-Switchable DHK Technology with Active Pressure Reduction | |||
| E138 A1 (US, CN) |
Device | DAP with two pressure chambers connected via exactly two solenoid valves (AS + VF) in series. Four operating modes: (a) normal forward stroke — small area, (b) pre-filling — large area (3× delivery rate), (c) return stroke — ring area, (d) pressure reduction directly via AS without ABS outlet valves. | DHK with AS/VF series connection |
| E138 A13 (US) |
Method | Diagnostic procedure: leak and air detection by correlating delivered volume (piston area × stroke) with expected p-V characteristic curve. Real-time diagnosis in both stroke directions without additional sensors. Critical for L4/5 autonomous vehicles. | Volume-pressure diagnostic |
| E138 A18/A19 (CN) |
Method | A18: Pressure reduction via bidirectional inlet valve + central outlet valve and/or directly via DAP. A19: Pressure reduction with DAP connected so only smaller effective piston area is active in forward stroke → finely metered pressure reduction; hydraulic "2-speed" effect for blending and ABS modulation. | DAP pressure reduction method & area switching |
Jurisdictions & Status
All members of the E138 patent family as of February 2026. All seven rights are granted.
| File No. | Country | Status | Type | Application No. | Filed | Grant No. | Granted |
|---|---|---|---|---|---|---|---|
| E138WOEP | EP | Granted | Patent | 15723949.2 | May 20, 2015 | EP3145771B1 | Nov. 7, 2018 |
| E138WOEPDE | DE | Granted | Patent (via EP) | 15723949.2 | May 20, 2015 | 502015006778.0 | Nov. 7, 2018 |
| E138WOEPFR | FR | Granted | Patent (via EP) | 15723949.2 | May 20, 2015 | EP3145771B1 | Nov. 7, 2018 |
| E138WOKR | KR | Granted | Patent | 10-2016-7035692 | May 20, 2015 | KR101978278B1 | May 8, 2019 |
| E138WOCN | CN | Granted | Patent | 201580026017.7 | May 20, 2015 | CN106458167B | Apr. 27, 2021 |
| E138WOUS1 | US | Granted | Patent (divisional) | 17/018,094 | May 20, 2015 | US10,940,840 B2 | Mar. 9, 2021 |
| E138WOCN1 | CN | Granted | Patent (divisional) | 202110355357.1 | May 20, 2015 | CN113147694B | Feb. 13, 2024 |
