Suspension control system

Patent metadata

Field	Value
Publication number	US-10703162-B2
Application number	US-201314410808-A
Country	US
Kind code	B2
Filing date	Jun 20, 2013
Priority date	Jun 29, 2012
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

A suspension control system allows a state variable of a vehicle used for the damper damping force control to be computed at a high precision without regards to the caster angle given to the suspension geometry. A suspension control system for a vehicle provided with a variable damper that can adjust a damping force according to an input signal comprises a wheel rotational speed sensor for detecting a wheel rotational speed, a gain circuit for computing the unsprung load of each wheel according to the wheel rotational speed variation detected by the wheel speed sensor, a single wheel model computing unit for computing the sprung velocity and the stroke speed by inputting the unsprung load to a single wheel model representing the behavior of the vehicle, and a damper control unit for controlling a damping force of the variable damper according to the computed sprung velocity and stroke speed.

First claim

The invention claimed is:

1. A suspension control system for a vehicle provided with a variable damper that can adjust a damping force according to an input signal, comprising:
a wheel rotational speed sensor for detecting a wheel rotational speed;
an un-sprung load computing means for computing an un-sprung load of the vehicle according to a wheel rotational speed variation detected by the wheel rotational speed sensor, the un-sprung load consisting of a road contact load variation of the vehicle;
a state variable computing means for computing state variables of the vehicle by feeding the un-sprung load to a vehicle model representing a behavior of a sprung mass and an un-sprung mass of the vehicle in relation to the un-sprung load, the state variables including a sprung velocity and a suspension stroke speed of the vehicle; and
a damper control means for controlling the damping force of the variable damper according to the computed state variables,
wherein the un-sprung load computing means converts the wheel rotational speed variation into the un-sprung load based on a relationship between the wheel rotational speed variation and the un-sprung load, the relationship being predetermined based on actually detected values of the wheel rotational speed and a road contact load.

2. The suspension control system according to claim 1 , further comprising a first filter for the wheel rotational speed sensor for a first frequency range corresponding to a vibration of the sprung mass, and a second filter for the wheel rotational speed sensor for a second frequency range higher than the first frequency range,
wherein the damper control means includes a sprung damping control means for controlling the damping force of the variable damper according to the wheel rotational speed variation filtered by the first filter, and an unsprung damping control means for controlling the damping force of the variable damper according to the wheel rotational speed variation filtered by the second filter.

3. The suspension control system according to claim 1 , further comprising a vehicle body speed estimating means for estimating a vehicle body speed according to a vehicle body acceleration of the vehicle, and a wheel rotational speed correcting means for computing a corrected wheel rotational speed by subtracting an estimated wheel rotational speed estimated from the vehicle body speed from a detected value of the wheel rotational speed sensor,
wherein the un-sprung load computing means is configured to compute the un-sprung load of the vehicle according to a wheel rotational speed variation of the corrected wheel rotational speed.

4. The suspension control system according to claim 3 , wherein the vehicle body speed estimating means estimates the vehicle body acceleration of the vehicle according to a drive/brake force of the vehicle and an inclination of a road surface.

5. The suspension control system according to claim 4 , wherein the vehicle body speed estimating means estimates a traveling resistance of the vehicle according to the detected wheel rotational speed, and estimates the vehicle body acceleration of the vehicle by taking into account the estimated traveling resistance.

6. The suspension control system according to claim 3 , further comprising a filter for a frequency range corresponding to a vibration of the sprung mass, the filter filtering the corrected wheel rotational speed so as to remove variation due to the vehicle body acceleration to thereby extract a corrected wheel rotational speed in the frequency range corresponding to the vibration of the sprung mass, wherein the un-sprung load computing means is configured to compute the un-sprung load of the vehicle according to a wheel rotational speed variation of the corrected wheel rotational speed extracted by the filter.

7. The suspension control system according to claim 1 , further comprising a cornering state variable computing means for computing a cornering state variable and a wheel rotational speed correcting means for correcting a detected value of the wheel rotational speed sensor according to the computed cornering state variable,
wherein the un-sprung load computing means computes the un-sprung load of the vehicle according to a wheel rotational speed variation of the corrected wheel rotational speed.

8. The suspension control system according to claim 1 , further comprising
a wheel rotational speed variation extracting means for extracting a wheel rotational speed variation of a frequency range corresponding to a sprung vibration of the vehicle according to the detected wheel rotational speed, such that the un-sprung load computing means computes the un-sprung load according to the wheel rotational speed variation extracted by the wheel rotational speed variation extracting means.

9. The suspension control system according to claim 1 , wherein
the wheel rotational speed sensor is provided on a front wheel, and the un-sprung load computing means computes the un-sprung load with respect to the front wheel,
the state variable computing means including a front wheel state variable computing means for computing the state variables of the vehicle associated with the front wheel, and a rear wheel state variable computing means for computing the state variables of the vehicle associated with a rear wheel according to the state variables computed by the front wheel state variable computing means.

10. The suspension control system according to claim 9 , wherein the un-sprung load computing means computes the un-sprung load associated with the front wheel, and the state variables computed by the front wheel state variable computing means include an unsprung position associated with the front wheel,
the rear wheel state variable computing means being configured to compute a road surface vertical position associated with the front wheel according to the unsprung load associated with the front wheel and the un-sprung position associated with the front wheel, and compute the state variables of the vehicle associated with ft the rear wheel according to the computed road surface vertical position associated with the front wheel.

11. The suspension control system according to claim 10 , wherein the rear wheel state variable computing means is configured to compute a road surface vertical position associated with the rear wheel by applying a time delay corresponding to a vehicle speed to the road surface vertical position associated with the front wheel, and compute the state variables of the vehicle associated with the rear wheel according to the road surface vertical position of the vehicle associated with the rear wheel.

Assignees

• Honda Motor Co Ltd

Inventors

• Kanda Ryoma
• Izawa Masaki

Classifications

• B60G17/0161

  mainly during straight-line motion (B60G17/0164 takes precedence) · CPC title

• B60G2500/106

  duty rate · CPC title

• B60G2400/202

  Piston speed; Relative velocity between vehicle body and wheel · CPC title

• B60G2400/206

  Body oscillation speed; Body vibration frequency · CPC title

• B60G2800/916

  Body Vibration Control · CPC title