E141 — HDS 2 Hybrid Pressure Control

HDS 2 is the result of a step-by-step development of brake-by-wire pressure control at IPGATE, expanding the degrees of freedom with each generation.

Generation 1 · 2005 — MUX Pressure Control (Patent Family E87 · 8 patents · 624 citations): Piston pressure control (PPC method) via brushless EC motor with Id/Iq vector control, adaptive map control, and sequential MUX valve control in a closed brake circuit. Limitation: during pressure reduction at one wheel, simultaneous pressure build-up is not possible.

Generation 2 · 2009 — HDS 1 — Plunger Flow Control (Patent Family E102 · 10 patents · 25 core inventions): Cascaded plunger flow control with simultaneous/partially simultaneous operation. Inner loop: piston position/speed. Outer loop: target pressure via pV characteristic curve. Adds wheel-selective PWM valve control and model-based sensorless pressure calculation per wheel.

Generation 3 · 2015 — HDS 2 — Hybrid Pressure Control (Patent Family E141 · 4 applications · 12 inventions): Volume control + time/PWM outlet valve control. All degrees of freedom: simultaneous build-up and reduction. Three delivery types (plunger, DAP, rotary pump). Dual sensor strategy, central outlet valve, regenerative braking blending, vibration-free delivery via PWM bypass.

1. Hybrid control with outlet valves as additional degree of freedom — Pressure reduction via outlet valves (AV) integrated as a controlled channel: individual wheel valves or a central outlet valve (ZAV). The delivery device acts as a dual control element: during reduction, the plunger actively controls the gradient via volume control, linearizing the non-linear outlet valve pressure curve.

2. Three delivery device types — Plunger (HDS 2.1): dual control for finely metered reduction. DAP (HDS 2.2): uninterrupted continuous delivery forward and return, solving the volume problem structurally. Rotary pump (HDS 2.3): cost-effective, requires outlet valve reduction.

3. Dual sensor strategy with offset compensation — Angle sensor for primary pressure control via delivery rate; pressure sensor for offset calibration after outlet valve reduction. Inherent redundancy for fail-operational systems at autonomy levels 3–5.

4. Solution to the volume problem (HDS 2.1) — In single-stroke piston systems, ABS operation drains volume continuously. HDS 2 solves this via preferred volume return to the working chamber during control, avoiding the conventional 150 ms interruption required for piston retraction and reservoir refill.

5. Valve reduction through central outlet valve (ZAV) — Asymmetric topology: ZAV connected to multiple consumers; at least one consumer retains an individual outlet valve for rapid selective reduction. Scalable architecture reducing solenoid valve count, cost, installation space, and weight.

6. Regenerative braking and advanced driving dynamics — Finely tuned blending: hydraulic pressure on the generator axle precisely adjusted to varying generator torque while simultaneously controlling the conventional axle. Supports wheel-specific blending for all-wheel recuperation and yaw moment generation during regenerative braking and steering.

7. Maximization of the pressure reduction gradient — For plunger and DAP systems: simultaneous reduction via delivery device and outlet valve. Critical for low-µ surfaces where outlet valve gradient alone is physically limited.

8. Vibration reduction via outlet valve bypass — PWM-controlled outlet valve opened simultaneously with delivery to divert and smooth pressure peaks and harmonics of piston pumps. Enables low-noise, vibration-free pressure build-up and precisely metered reduction — essential for premium BEVs and autonomous vehicles where brake noise is no longer masked by engine sound.

Patent family E141 introduces HDS 2 — the third generation of IPGATE's IBS pressure control technology. It combines precise volume control via the delivery device with time or PWM control of outlet valves, enabling simultaneous pressure build-up in one consumer and reduction in another for the first time.