Hydraulic Brake Valve Control for Low-Heat Automated Driving Stops
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Solution Overview
Problem
Existing automated driving vehicles face challenges in efficiently managing thermal loads on pumps during frequent deceleration and stopping, particularly in vehicles like forklifts, where prolonged motor drive times increase thermal stress.
Innovation Solution
The automated driving vehicle incorporates a solenoid valve unit that can switch between connection and checked states, allowing controlled hydraulic oil flow to brake systems, enabling intermittent motor operation to maintain braking force without continuous pumping, thus reducing motor drive time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump is driven continuously to maintain braking force during frequent deceleration and stopping, then the braking force is maintained reliably, but the motor drive time increases causing thermal load on the pump
Solution Approach 1:
The solenoid valve is switched between open and closed states periodically to control hydraulic oil flow, allowing the pump to operate intermittently rather than continuously. This periodic switching maintains braking force while reducing motor drive time and thermal load on the pump.
Solution Approach 2:
The solenoid valve is opened in advance before braking is needed, allowing hydraulic oil to be supplied to the brake in advance. This preliminary action ensures braking force is ready when needed while allowing the pump to stop earlier, reducing thermal load.
2Temperature
If the motor drive time is shortened to reduce thermal load, then the thermal load on the pump is reduced, but the braking force maintenance may be compromised
Solution Approach 1:
The solenoid valve acts as an intermediary between the pump and the brake, controlling the flow of hydraulic oil. This allows the pump to operate for shorter periods while still maintaining adequate braking force by precisely controlling when and how much oil reaches the brake.
Solution Approach 2:
The brake system maintains its braking force by utilizing the hydraulic oil already supplied to it, without requiring continuous pumping. The solenoid valve enables the system to self-maintain braking force through controlled oil retention and pressure management.
3Temperature
If the solenoid valve unit is added to control hydraulic oil flow, then the motor drive time is reduced and thermal load is managed, but the device complexity increases
Solution Approach 1:
The solenoid valve unit serves multiple functions: controlling hydraulic oil flow direction, regulating pump operation timing, maintaining braking force, and managing thermal load. This multi-functionality justifies the added component by providing several benefits from a single device.
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
This configuration effectively reduces motor operation time, manages thermal loads, and maintains braking force efficiently, ensuring stable vehicle stops even on slopes, while simplifying the brake system's configuration.
Implementation Method 1
The solenoid valve unit is switchable, based on a signal from the controller, between a connection state in which connection between the output port and the input port is not shut off and a checked state in which inflow of the hydraulic oil from the output port to the input port is restricted
Implementation Method 2
The braking force applying device converts hydraulic pressure from brake oil serving as hydraulic oil into braking force that is applied to the wheel
Implementation Method 3
a brake that generates braking force on a wheel of the vehicle body in accordance with pressure of the hydraulic oil
Data Source
AI summary
An automated driving vehicle includes a hydraulic oil tank in which hydraulic oil is stored, a brake that generates braking force in accordance with pressure of hydraulic oil, a pump connected to the hydraulic oil tank, a motor that drives the pump, a controller that controls the motor, and a solenoid valve unit that includes an input port connected to an input oil passage connected to the pump and an output port connected to an output oil passage connected to the brake. The solenoid valve unit is switchable, based on a signal from the controller, between a connection state in which connection between the output port and the input port is not shut off and a checked state in which inflow of hydraulic oil from the output port to the input port is restricted while outflow of hydraulic oil from the input port to the output port is allowed.