Vehicle Brake Device Segmentation for Regenerative Braking
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Solution Overview
Problem
Existing brake devices for vehicles face challenges in fully utilizing regenerative brake force due to pressure reactions from accumulators during regenerative braking, leading to discomfort and potential noise from hydraulic fluid pulsation and water hammer effects.
Innovation Solution
A brake device with dual hydraulic brakes and a regenerative brake system, utilizing first and second pressure increasing and decreasing valves to manage brake fluid pressure, allowing fluid to escape into an accumulator while minimizing accumulator reaction, thus enhancing regenerative brake force utilization and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pressure decreasing valve is opened to allow brake fluid to escape into the accumulator, then comfortable brake feel is achieved, but accumulator reaction pressure is applied to the vehicle wheels which limits regenerative brake force utilization
Solution Approach 1:
The brake system is divided into two independent hydraulic circuits: a first hydraulic circuit for the first hydraulic brake that communicates with the accumulator, and a second hydraulic circuit for the second hydraulic brake that does not communicate with the accumulator. This segmentation allows selective application of accumulator reaction pressure to only one circuit, enabling comfortable brake feel in the first circuit while fully utilizing regenerative brake force in the second circuit.
Solution Approach 2:
Different quality characteristics are applied to different parts of the system: the first hydraulic circuit is designed with accumulator communication to provide comfortable brake feel, while the second hydraulic circuit is designed without accumulator communication to maximize regenerative brake force utilization. This local differentiation resolves the contradiction by allowing both functions to coexist in different parts of the system.
2Stress or pressure
If the pressure decreasing valve is fully opened or fully closed with intermittent operation for exhaust amount adjustment, then pressure control is achieved, but pulsation is produced in the brake fluid which may cause noise from water hammer
Solution Approach 1:
The pressure control function is segmented between two independent circuits. The first hydraulic circuit uses intermittent valve operation for exhaust amount adjustment, while the second hydraulic circuit maintains continuous pressure control without intermittent operation. This segmentation eliminates pulsation and water hammer noise in the second circuit while maintaining pressure control capability in the first circuit.
Solution Approach 2:
The second hydraulic circuit maintains continuous pressure control action without intermittent valve opening and closing, ensuring smooth brake fluid flow that prevents pulsation and water hammer noise. This continuous operation preserves the useful action of pressure control while eliminating harmful pulsations.
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 solution effectively suppresses accumulator reaction influence, ensuring comfortable brake feel and full utilization of regenerative brake force, while minimizing noise and vibration, by strategically controlling pressure valves during regenerative braking.
Implementation Method 1
An object of the regenerative brake being used for such a brake device for a vehicle is to convert kinetic energy of a vehicle wheel at the time of braking into electrical energy
Implementation Method 2
a hydraulic brake for producing a hydraulic brake force using a hydraulic pressure being produced according to a brake operation of a driver
Implementation Method 3
brake fluid escapes into a low pressure accumulator via a pressure decreasing valve
Data Source
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AI summary
The present invention aims to reduce dragging of a brake and to use sufficiently and effectively a regenerative brake force by suppressing an influence of a reaction of an accumulator when a pressure decreasing valve is opened. There is provided a brake device for a vehicle, that includes at least a first hydraulic brake and a second hydraulic brake which produce hydraulic brake forces, and a regenerative brake which produces a regenerative brake force, and that performs a distribution of the hydraulic brake force and the regenerative brake force with respect to a driver request brake force, including: a first pressure increasing valve which can increase a pressure of brake fluid supplied to the first hydraulic brake; a first pressure decreasing valve which can decrease the pressure of the brake fluid supplied to the first hydraulic brake; a second pressure increasing valve which can increase a pressure of brake fluid supplied to the second hydraulic brake; and a second pressure decreasing valve which can decrease the pressure of the brake fluid supplied to the second hydraulic brake, wherein the first pressure decreasing valve and the second pressure decreasing valve communicate with an accumulator, and wherein while the driver request brake force is covered by only the regenerative brake force, the first pressure increasing valve and the first pressure decreasing valve are opened, and the second pressure increasing valve and the second pressure decreasing valve are closed.