JP-2026074772-A - Vehicle speed estimation device and brake control device

JP2026074772AJP 2026074772 AJP2026074772 AJP 2026074772AJP-2026074772-A

Abstract

[Problem] The objective is to accurately estimate the vehicle speed when the drive wheels are spinning. [Solution] The vehicle speed estimation device (control unit 20) is a device for estimating the estimated vehicle speed of a front-wheel drive or rear-wheel drive vehicle. The vehicle speed estimation device has a maximum wheel speed determination means 21, a minimum driven wheel speed determination means 22, and a vehicle speed estimation means 23. The maximum wheel speed determination means 21 determines the maximum wheel speed, which is the highest among the wheel speeds of all wheels. The minimum driven wheel speed determination means 22 determines the minimum driven wheel speed, which is the lowest among the wheel speeds of multiple driven wheels, by limiting it with a lower limit calculated based on the previously estimated vehicle speed. The vehicle speed estimation means 23 uses the smaller of the maximum wheel speed and the minimum driven wheel speed as the estimated vehicle speed. [Selection Diagram] Figure 4

Inventors

弘山一樹

Assignees

Ａｓｔｅｍｏ株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (7)

A vehicle speed estimation device for estimating the estimated vehicle speed of a front-wheel drive or rear-wheel drive vehicle, A means for determining the maximum wheel speed which is the highest among all the wheel speeds, A minimum driven wheel speed determination means determines the minimum driven wheel speed by limiting the minimum wheel speed among multiple driven wheel speeds by a lower limit calculated based on the previously estimated vehicle speed, and A vehicle speed estimation device characterized by having a vehicle speed estimation means that uses the smaller of the maximum wheel speed and the minimum driven wheel speed as the estimated vehicle speed.
The vehicle speed estimation device according to claim 1, characterized in that the minimum driven wheel speed determination means determines the minimum driven wheel speed by limiting it with an upper limit and a lower limit calculated based on the previously estimated vehicle speed.
The vehicle speed estimation device according to claim 2, characterized in that the upper limit is calculated by adding a pre-set first predetermined value to the previously estimated vehicle speed.
The vehicle speed estimation device according to claim 1, characterized in that the lower limit is calculated by subtracting a pre-set second predetermined value from the previously estimated vehicle speed.
A vehicle speed estimation device for estimating the estimated vehicle speed of a front-wheel-drive vehicle, A means for determining the maximum wheel speed which is the highest among all the wheel speeds, A minimum driven wheel speed determination means determines the minimum driven wheel speed by limiting the minimum wheel speed among multiple rear wheel speeds by a lower limit calculated based on the previously estimated vehicle speed, and A vehicle speed estimation device characterized by having a vehicle speed estimation means that uses the smaller of the maximum wheel speed and the minimum driven wheel speed as the estimated vehicle speed.
The vehicle speed estimation device according to claim 5, characterized in that the minimum driven wheel speed determination means determines the minimum driven wheel speed by limiting it with an upper limit and a lower limit calculated based on the previously estimated vehicle speed.
A brake control device comprising a vehicle speed estimation device according to claim 5 or claim 6, and controlling a parking brake mechanism that applies braking force to the rear wheels, Based on the estimated vehicle speed estimated by the vehicle speed estimation device and the wheel speed of the rear wheels, it is possible to determine whether or not the rear wheels are likely to lock up. A brake control device characterized in that, when it is determined that the rear wheels are about to lock up while the vehicle is in motion and the parking brake mechanism is applying braking force to the rear wheels, the application of braking force by the parking brake mechanism is released.

Description

This invention relates to a vehicle speed estimation device and a brake control device. Conventionally, a vehicle speed estimation device is known that estimates the vehicle speed by setting limits on the acceleration or deceleration of the front wheel speed (see Patent Document 1). International Publication No. 2021/192449 This is a diagram showing the configuration of a vehicle equipped with an electric parking brake control device according to an embodiment of the present invention.This diagram shows a drum brake and a parking brake mechanism. Diagram (a) shows the brakes not applied, and diagram (b) shows the brakes applied by the parking brake mechanism.These are cross-sectional views showing the electric actuator of the parking brake mechanism, with (a) showing the release state and (b) showing the applied state.This is a block diagram showing the configuration of the control unit.This is a flowchart showing the operation of the control unit.This graph shows the relationship between the wheel speed of each wheel and the estimated vehicle speed when the parking brake is applied while the vehicle is traveling on a low-friction surface.This graph shows the relationship between the wheel speed of each wheel and the estimated vehicle speed when brake fluid pressure is generated while a vehicle is traveling on a high-friction surface.This graph shows the relationship between the wheel speed of each wheel and the estimated vehicle speed when the front wheels spin on a low-friction surface.This graph shows the relationship between the wheel speed of each wheel and the estimated vehicle speed when a vehicle accelerates on a high-friction surface. Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. As shown in Figure 1, the vehicle CR is equipped with drum brakes D, a parking brake mechanism 200, and a vehicle brake fluid pressure control device 100. The vehicle CR in this embodiment is a front-wheel drive vehicle. The drum brakes D are provided on each of the four wheels W. The parking brake mechanism 200 is a mechanism that mechanically operates the drum brakes D on the rear wheels (the two rear wheels W) to apply braking force to the rear wheels. The parking brake mechanism 200 is provided for each of the drum brakes D on the left and right rear wheels. The vehicle brake fluid pressure control device 100 is designed to appropriately control the braking force applied to each wheel W of the vehicle CR. It primarily comprises a hydraulic unit 10 equipped with oil passages (hydraulic passages) and various components, and a control unit 20 for appropriately controlling the various components within the hydraulic unit 10. The hydraulic unit 10 is connected via oil passages to the master cylinder MC, which generates brake fluid pressure when the brake pedal BP is pressed, and also to the wheel cylinders D4 of each drum brake D via oil passages. The hydraulic unit 10 includes valves, pumps, and other components for controlling the brake fluid pressure applied to the wheel cylinders D4. The control unit 20 is an example of a vehicle speed estimation device and brake control device, and has the function of controlling the valves and pumps in the hydraulic unit 10 and the function of controlling the parking brake mechanism 200. The control unit 20 is connected to a wheel speed sensor 91 for detecting the wheel speed of the wheel W, and a parking switch 92 for switching the state of the drum brake D between the apply state and the release state. Here, the apply state refers to the state in which braking force is generated from the drum brake D. The release state refers to the state in which the braking force of the drum brake D is released. The parking switch 92 is switchable between the apply position and the release position. When the parking switch 92 is in the apply position, it outputs an apply signal to the control unit 20 to set the drum brake D to the apply state. When the parking switch 92 is in the release position, it outputs a release signal to the control unit 20 to set the drum brake D to the release state. The control unit 20 includes, for example, a CPU, RAM, ROM, and input/output circuits. It performs control by processing various calculations based on inputs from the wheel speed sensor 91, parking switch 92, and programs and data stored in the ROM. As shown in Figures 2(a) and 2(b), the drum brake D comprises a drum D1, a brake shoe D2, a return spring D3, and a wheel cylinder D4. The drum D1 is a cylindrical component that rotates integrally with the wheel W. The brake shoe D2 is an arc-shaped member extending along the inner circumferential surface of the drum D1. By pressing against the inner circumferential surface of the drum D1, it applies braking force to the wheel W. Two brake shoes D2 are provided along the inner circumferential surface of the drum D1. Each of the two brake shoes D2 is rotatably supported at one end by a support