Hydraulic Wheel Speed Control via Pressure Ratio

Solution Overview

Problem

Current all-wheel drive work machines require multiple clutches to control the speed of hydraulically driven wheels, increasing complexity and cost, and are prone to inconsistent wheel speed due to clutch damage during operation.

Innovation Solution

A controller system with sensors to monitor wheel speed, fluid pressure, and return pressure, allowing for selection of control configurations for the fluid pump to manage slippage and drag, thereby controlling the speed of hydraulically driven wheels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple clutches are used to control the speed of hydraulically driven wheels, then the speed control capability is improved, but the device complexity and cost increase

Engineering Contradiction:

Improvespeed control capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the speed control function into the hydraulic system by using a single variable displacement motor and controller instead of multiple mechanical clutches. The controller integrates speed sensing, pressure regulation, and motor control to achieve wheel speed control through hydraulic means, eliminating the need for separate clutch mechanisms on each wheel.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical clutch system with a hydraulic control system. Instead of using mechanical friction-based clutches to control wheel speed, the system uses a variable displacement motor controlled by hydraulic pressure regulation, substituting mechanical control with hydraulic and electronic control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If multiple clutches are used to control the speed of hydraulically driven wheels, then the speed control capability is improved, but the cost increases

Engineering Contradiction:

Improvespeed control capabilityVSAvoidcost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the speed control function into the hydraulic system by using a single variable displacement motor and controller instead of multiple mechanical clutches. The controller integrates speed sensing, pressure regulation, and motor control to achieve wheel speed control through hydraulic means, eliminating the need for separate clutch mechanisms on each wheel.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical clutch system with a hydraulic control system. Instead of using mechanical friction-based clutches to control wheel speed, the system uses a variable displacement motor controlled by hydraulic pressure regulation, substituting mechanical control with hydraulic and electronic control mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If clutches are used to control wheel speed, then speed control is achieved, but reliability decreases due to clutch damage during operation

Engineering Contradiction:

Improvewheel speed controlVSAvoidreliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the mechanical clutch system with a hydraulic control system. Instead of using mechanical friction-based clutches to control wheel speed, the system uses a variable displacement motor controlled by hydraulic pressure regulation, substituting mechanical control with hydraulic and electronic control mechanisms that have higher reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system incorporates sensors that continuously monitor wheel speed and hydraulic pressure, with the controller automatically adjusting motor displacement to maintain proper speed control. This closed-loop self-regulating system eliminates the need for mechanical clutches that require manual intervention or can fail due to wear.

Inventive Principle:

Principle #25Self-service

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 effectively reduces the complexity and cost of speed control by eliminating the need for multiple clutches and ensures consistent wheel speed operation by dynamically adjusting fluid pressure based on sensed parameters.

Implementation Method 1

The first conduit connects an output from a fluid pump to an input to at least one motor. The second conduit connects an output of the at least one motor to an input of the fluid pump.

Methodology Applied

Scientific EffectHydraulic pressure transmission: Hydraulic Press

Data Source

PatentUS9702458B2Pressure and speed control for a vehicle

Publication Date: 2017.07.11 CATERPILLAR INC

AI summary

A system and method configured to select a control configuration for a hydraulic fluid system. The system includes a controller having at least one sensor and a processor. The controller is configured to sense a feed pressure and a return pressure of a fluid within the hydraulic fluid system and a speed of a driven set of wheels and a speed of an idle set of wheels. The driven set of wheels are drivingly coupled to an engine, and the idle set of wheels are drivingly coupled to the hydraulic fluid system. The controller is further configured to select a control configuration for the hydraulic fluid system based on a ratio between the feed pressure and the return pressure, and further based on a ratio between the speed of the driven set of wheels and the speed of the idle set of wheels.