Land vehicles – Suspension modification enacted during travel – Suspension stiffness for ride comfort
Reexamination Certificate
1999-04-05
2001-04-03
Mai, Lanna (Department: 3619)
Land vehicles
Suspension modification enacted during travel
Suspension stiffness for ride comfort
C280S124157
Reexamination Certificate
active
06209887
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to vehicle suspensions. More particularly, this invention relates to an electronically controlled vehicle suspension that is dynamically adjustable while the vehicle is in motion.
A variety of vehicle suspension systems are known. Typical passenger vehicles include basic suspension systems while heavy duty vehicles sometimes include more complex systems having adjustable features. For example, the amount of air within hydraulic shock absorbers can be adjusted to provide a firmer or softer ride. The limitations on such systems, however, include the fact that the adjustment can only be made when the vehicle is stationary (i.e., no dynamic adjustments are possible while the vehicle is in motion). Conventional systems are not capable of adjusting the suspension system in response to varying road conditions while the vehicle is in transit.
Heavy duty vehicles present special considerations including the need to reduce the amount of energy transferred to the driver of the vehicle. The large masses associated with heavy duty vehicles typically require suspension systems that support the loads but, at the same time, render the vehicle relatively uncomfortable for a driver. The typical experience of a driver of a heavy duty vehicle includes an excessive amount of vibration or bouncing of the driver's seat.
Additionally, the cargo within the heavy duty vehicle is typically subjected to undesirably large amounts of energy transfer caused by forces imposed on the vehicle by road conditions. This is especially troublesome when transporting relatively fragile or sensitive cargo.
In view of the shortcomings and drawbacks associated with conventional suspension systems, it would be desirable to provide a suspension system that is dynamically adjustable to compensate for varying road conditions. This invention provides such a suspension system that minimizes the amount of energy transferred to a driver, passenger or cargo within a vehicle that is caused by variations in a road surface, for example. Additionally, a suspension designed according to this invention provides enhanced safety features as will be described below.
SUMMARY OF THE INVENTION
In general terms, this invention is a vehicle suspension system that is dynamically adjustable to minimize the amount of energy transfer to a driver, passenger or cargo within a vehicle. Although this invention is especially useful for heavy duty vehicles, the application of this invention is not necessarily limited to such vehicles.
A suspension system designed according to this invention includes several basic components. A force absorbing device has an adjustable force absorbing capacity. A sensor is provided that detects a force imposed on a first portion of the suspension system while the vehicle is travelling along a road surface. An electronic controller is in communication with the sensor and the force absorbing device. The electronic controller determines an amount of displacement and an amount of acceleration of the first portion of the suspension system such as a wheel, based upon an output of the sensor. An electrically activated force imposing device imposes a force on a second portion of the suspension system responsive to the electronic controller such that the effects of the force imposed on the first portion of the suspension system that otherwise would be imposed on the driver or cargo is minimized.
The electrically activated force imposing device preferably is a piezoelectric actuator that is responsive to a command from the electronic controller within approximately one millisecond of the recognition of the force imposed on the first vehicle wheel. The force imposed by the piezoelectric actuator effectively counteracts the force from the road and improves the comfort and consistency of the ride of the vehicle. Additionally, the force absorbing device preferably has an air chamber with an inlet and an outlet so that an amount of air within the chamber can be selectively adjusted through commands from the electronic controller to adjust the force absorbing capacity of the suspension system.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.
REFERENCES:
patent: 5020781 (1991-06-01), Huang
patent: 5072965 (1991-12-01), Wada et al.
patent: 5217246 (1993-06-01), Williams et al.
patent: 5243525 (1993-09-01), Tsutsumi et al.
patent: 5390949 (1995-02-01), Naganathan et al.
patent: 5527060 (1996-06-01), Kutsche
patent: 5603387 (1997-02-01), Beard et al.
Carlson & Gaskey & Olds
Jasmin Lynda
Mai Lanna
Meritor Heavy Vehicle Systems LLC
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