Multi-Axle Brake Pressure Layout Without Inter-Axle Hydraulic Lines

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing braking systems for vehicles with multiple axles are bulky, require complex hydraulic connections, and are prone to air accumulation, which can impair functionality and necessitate manual intervention for pressure adjustment.

Innovation Solution

A braking system with a compact design that eliminates hydraulic lines between axles, featuring a motorized brake pressure build-up device for autonomous pressure control, synchronized brake fluid flows to prevent air accumulation, and a fallback mechanism for mechanical intervention, ensuring reliable braking without manual input.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional hydraulic lines are used to connect brake circuits between axles, then braking pressure can be transmitted across the vehicle, but the system becomes bulky and requires complex hydraulic connections

Engineering Contradiction:
Improvebraking pressure transmissionVSAvoidhydraulic connections
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The brake system is divided into axially isolated brake circuits, where each axle unit has its own independent brake circuit. This segmentation eliminates the need for complex inter-axle hydraulic connections while maintaining reliable braking pressure transmission within each axial circuit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A motorized brake pressure build-up device acts as an intermediary between the brake pedal and the wheel brake cylinders. This device generates braking pressure independently for each axle unit, replacing the need for traditional hydraulic lines that would connect axles directly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If traditional brake systems are used, then hydraulic pressure can be distributed to all wheels, but air accumulation occurs in the hydraulic lines which impairs functionality

Engineering Contradiction:
Improvebraking functionalityVSAvoidair accumulation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By segmenting the brake system into axially isolated circuits with independent pressure build-up devices, the system eliminates long hydraulic lines where air could accumulate. Each compact axial circuit minimizes air entrapment risk while maintaining full braking functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The motorized brake pressure build-up device automatically generates and regulates braking pressure without requiring manual bleeding or intervention. The system self-regulates pressure in each axial circuit, preventing air accumulation issues that plague traditional hydraulic systems.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If manual pressure adjustment is required for brake circuits, then braking pressure can be controlled, but the system requires driver intervention and is not fully autonomous

Engineering Contradiction:
Improvebrake pressure controlVSAvoidautonomous pressure setting
Core Design Contradiction:
Ease of operationVSExtent of automation

Solution Approach 1:

The motorized brake pressure build-up device serves as an automated intermediary between the driver's brake input and the actual braking force applied to each axle. This intermediary automatically adjusts and maintains optimal braking pressure without requiring manual intervention, achieving full automation while preserving ease of operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Traditional mechanical brake systems require manual pressure application and adjustment by the driver. This invention replaces that mechanical system with motorized pressure build-up devices that automatically generate and control braking pressure, substituting manual mechanical operation with automated electro-mechanical control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If hydraulic lines span the entire vehicle length, then all axles can be connected to a central brake system, but installation space is consumed and installation becomes complex

Engineering Contradiction:
Improvebrake system integrationVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The brake system is segmented into independent axial units, each with its own compact pressure build-up device. This eliminates the need for long hydraulic lines spanning the vehicle, significantly reducing installation space while maintaining reliable brake system integration through standardized axial interfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The motorized brake pressure build-up device merges multiple functions (pressure generation, regulation, and distribution) into a single compact unit at each axle. This consolidation eliminates the need for separate hydraulic lines and intermediate components, reducing overall installation space while ensuring reliable system integration.

Inventive Principle:
Principle #5Merging (Combining)

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

The system achieves a compact, cost-effective design with reliable, autonomous braking, preventing air accumulation and enabling fail-safe operation, even in the event of hydraulic leaks, while maintaining low noise and vibration levels.

Implementation Method 1

a motorized brake pressure build-up device for autonomously building up brake pressure in the wheel brake cylinders by transferring brake fluid from the brake fluid reservoir to the wheel brake cylinders

Methodology Applied
Scientific EffectHydraulic pressure transfer: Hydraulic Press

Implementation Method 2

the first axle unit is flushed with synchronized brake fluid flows for pressure build-up and pressure release in its first and second wheel brake cylinders

Methodology Applied
Scientific EffectFluid flow flushing:

Implementation Method 3

ensure such a thorough flushing of the first axle unit that no accumulation of air in the first axle unit is possible

Methodology Applied
Scientific EffectAir removal through flushing:

Data Source

PatentEP4387876B1Brake system and method for braking a vehicle having at least two axles
Publication Date: 2026.03.18 ROBERT BOSCH GMBH
  • EP4387876B1 patent drawingFigure 1
  • EP4387876B1 patent drawingFigure 2
  • EP4387876B1 patent drawingFigure 3

AI summary

The invention relates to a brake system for a vehicle having at least two axles, with a first axle unit (10) which can be mounted or is mounted on a first axle of the vehicle and has a motorized brake pressure build-up device (12), a first wheel brake cylinder (14a) and a second wheel brake cylinder (14b), and with a second axle unit which can be mounted or is mounted on a second axle of the vehicle and is formed separately hydraulically from the first axle unit (10), wherein the first axle unit (10) comprises a first outlet valve (18a) which is assigned to the first wheel brake cylinder (14a) and a second outlet valve (18b) which is assigned to the second wheel brake cylinder (14b), and brake fluid can be let out of the first wheel brake cylinder (14a) via the first outlet valve (18a) and out of the second wheel brake cylinder (14b) via the second outlet valve (18b) into the connected brake fluid reservoir (16). The invention likewise relates to a method for braking a vehicle having at least two axles.