Nissan Motor Company Limited

Kensuke Fukuyama

Naoto Fukushima

Itaru Fujimura

Yohsuke Akatsu

Masaharu Sato

Yukio Fukunaga

Yosuke Akatsu

Masaharu Satoh

Takeshi Kimura

Masahiro Tsukamoto

Yoshiki Yasuno

Hiroshi Tsunehara

Hideo Tobata

Kenro Takahashi

A yaw rate estimating apparatus is provided to estimate a yaw rate more accurately even if a vehicle is in a turn. A gain correction k for precluding an error in an estimated yaw rate due to tire deformation during a turn is predetermined for a lateral acceleration based on corresponding vehicle data. The gain correction k is provided in a gain correction characteristic map, in which the gain correction k is set to decrease as the lateral acceleration increases. The corresponding gain correction k is obtained from the gain correction characteristic map based on the detected lateral acceleration Y while the vehicle is in a non-controlled state. The estimated yaw rate is obtained by multiplying a yaw rate, which is estimated based on a wheel speed difference between left and right non-driving wheels and a tread, by the gain correction.

Yaw rate estimating apparatus

A vehicle behavior control system comprises a controller for determining a sensed steering angle from a steering amount signal and a neutral detection signal from a steering angle sensor, and performs a behavior control operation to reduce a deviation of a sensed actual motion variable such as a vehicle yaw rate from a target motion variable determined from the sensed steering angle. When the neutral detection signal is not available just after a start of the engine, the controller determines the target motion variable from an estimated steering angle instead of the sensed steering angle, and immediately starts controlling the vehicle behavior without delay by, for example, controlling the braking forces of the individual wheels.

Vehicle behavior control system

An apparatus for estimating vibration input to be transferred from a road surface to a suspension device of a vehicle. The apparatus converts stroke displacement values (S.sub.FL, S.sub.FR) detected by stroke sensor (27FL, 27FR) arranged on locations near the front wheels into stroke speed values (S.sub.VFL, S.sub.VFR) by differentiating circuits (41a, 41b) including a high-pass filer whose cutoff frequency (f.sub.HC) is set at substantially twice the spring-bottom resonance frequency (20 Hz, for example). The apparatus further converts body work vertical acceleration values (Z.sub.GFL, Z.sub.GFR) detected by vertical acceleration sensors (28FL, 28FR) arranged on locations near the front wheels into spring-top speed values (Z.sub.VFL, Z.sub.VFR) by integrating circuits (41c, 41d) including a low-pass filter whose cutoff frequency (f.sub.LC) is set at nearly one sixth of the spring-top resonance frequency (0.2 Hz, for example). The apparatus adds these speed values to each other by adders (41e, 41f) to provide differential values (x.sub.OFL ', x.sub.OFR ' ) of the spring-bottom displacement values obtained by accurately estimating the vibration input from a road surface by cancelling the spring-top speeds with each other.

Apparatus for estimating vibration input to a suspension device

An active suspension system is provided which includes hydraulic cylinders for suppressing rolling motion of a vehicle body. The system is responsive to lateral acceleration acting on the vehicle body to provide a control signal for supplying hydraulic pressure to the cylinders for anti-rolling control. The control signal includes first and second pressure control signals. The first pressure control signal commands supply of hydraulic pressure for providing an anti-rolling moment, while the second pressure control signal commands supply of hydraulic pressure for supporting a portion of the static load of the vehicle body to maintain the vehicle body at a target height level. The system is further responsive to increase in lateral acceleration to modify the second pressure control signal to reduce the hydraulic pressure for supporting the portion of static load, thereby compensating for forces acting to raise the vehicle body caused by the anti-rolling control for establishing a constant vehicular height level irrespective of variation in the lateral acceleration acting on the vehicle body.

Automotive active suspension system for regulating vehicular height

An actively controlled suspension system for automotive vehicles includes a lateral acceleration sensor and a controller for suppressing rolling of the vehicle. The controller controls a distribution ratio of anti-roll moment or lateral load shift between a driven wheel and a non-driven wheel so as to enhance steering characteristics of the vehicle. The controller changes the distribution ratio depending on both the lateral acceleration and the wheel speed difference between the driven wheel speed and the non-driven wheel speed such that the distribution ratio at a non-driven wheel side of suspension system is increased from a designated reference value according to the increase in the wheel speed difference and a rate of change in the distribution ratio is attenuated towards the designated reference value according to the increase in the lateral acceleration.

Actively controlled suspension system for automotive vehicles

An automotive suspension control system for anti-rolling motion control is provided. This system serves to adjust wheel loads acting on driven wheels when a wheel speed difference between the driven wheels is greater than a preselected value, concluding that slippage occurs at one of the driven wheels, the adjustment is carried out for securing traction of a slipping driven wheel. The system is responsive to lateral acceleration acting on a vehicle body to decrease a degree of adjustment of the wheel loads according to increase in the lateral acceleration for enhancing cornering stability on road surfaces having different friction coefficients.

Automotive active suspension system for anti-rolling control

An active suspension system for an automotive vehicle is arranged to regulate the attitude of a vehicle body in a flat or balanced state by controlling hydraulic cylinders respectively disposed between a vehicle body and a road wheel, in response to an attitude change of the vehicle body. The active suspension system comprises electromagnetically operated variable vibration attenuation valves, each of which is fluidly connected with each hydraulic cylinder and is followed by an accumulator. Each variable vibration attenuation valve is adapted to be variable in its attenuation constant in response to a vertical acceleration experienced by the road wheel. The variable vibration attenuation valve takes on a low attenuation constant to maintain a high riding quality of the vehicle under a normal cruising condition, and a high attenuation constant to suppress the response of the road wheel under a rough road cruising condition.

Active suspension system

A suspension control system employs a first lateral acceleration sensor for monitoring a lateral acceleration at a first point on a vehicular body and a second lateral acceleration sensor for monitoring lateral acceleration at a second point on the vehicular body, which second point is provided at a longitudinally offset position from the first point. A controller derives a lateral shifting of vehicular load at the front suspension systems on the basis of a first lateral acceleration monitored by the first lateral acceleration sensor, and a lateral shifting of the vehicular load at a rear suspension system on the basis of a second lateral acceleration monitored by the second lateral acceleration sensor. Control for front and rear suspension systems is performed independently on the basis of the lateral load shifting at the front and rear suspension systems.

Suspension control system with variable steering characteristics

An active suspension system for an automotive vehicle is provided which regulates relative displacement between a vehicle body and wheels. This suspension system includes first and second gain controllers associated with hydraulic cylinders for supressing vehicular rolling based on lateral acceleration acting on the vehicle body. The first and second gain controllers amplify the level of the lateral acceleration, monitored by a sensor, by first and second gains respectively to vary pressure of the hydraulic cylinders. The suspension system further includes a low-pass filter which restricts a frequency of a signal output from the acceleration sensor high than a preselected cutoff frequency to decrease the second gain relative to the first gain to reduce the degree of load shift for the rear wheels relative to that of the front wheels.

Control system for active suspension which distributes load according to

A pressure supply network for an active suspension system employs a strategy for predicting consumed fluid flow rate on the basis of bounding and rebounding stroke between a vehicular body and a suspension member rotatably supporting a vehicular wheel. A discharge rate of a fluid pump disposed in the pressure supply network is controlled on the basis of the predicted fluid flow rate.

Pressure supply network for active suspension system and control therefor

A fluid supply system is provided for an active vehicle suspension system, for supplying fluid pressure for a hollow working cylinder via a pressure control valve for adjusting suspension characteristics of the vehicle in order to suppress vehicular attitude changes and to absorb road shock vibration, the system having a pressurized fluid source unit for circulating a pressurized fluid through a fluid circuit extending via the pressure control valve and the working cylinder. A first sensor is provided for monitoring a relative displacement between the body of the vehicle and a suspension member rotatably supporting a road wheel thereof, for producing a relative displacement magnitude indicative signal. A second sensor is provided for monitoring a lateral acceleration exerted on the vehicle body. A predicted fluid flow amount through said fluid circuit is derived on the basis of the relative displacement indicative signal to produce a predicted fluid flow amount indicative signal. A magnitude of lateral acceleration greater than or equal to a predetermined acceleration criterion is detected to produce an acceleration detection signal. The fluid supply amount from the pressurized fluid source unit is derived of the basis of the predicted fluid flow amount for controlling the pressurized fluid source unit in order to adjust the supply amount of fluid toward the derived fluid supply amount in response to the acceleration detection signal for increasing the supply amount.

Fluid supply circuit for active suspension system with variable fluid

An active suspension system utilizes an acceleration exerted on a vehicle body and a stroke magnitude in relative displacement between the vehicle body and a suspension member as parameters for controlling discharge rate of pressure medium fluid from a pressure source unit. The pressure source unit is normally driven at limited discharge rate for minimizing driving power consumption. The pressure source unit is responsive to the vertical acceleration greater than a predetermined acceleration criterion and to vertical stroke magnitude greater than a predetermined stroke criterion to increase discharge rate for compensating pressure medium fluid amount to be consumed for suspension control.

Pressure medium fluid circuit for active suspension system with variable

A hydraulic circuit for an active suspension system employs a pressure accumulator connected to a drain line at an orientation upstream of a pilot operated operational one-way check valve. The pressure accumulator absorbs back pressure generated in the drain line due to flow resistance in the drain line.

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Kanagawa, Japan

Kensuke Fukuyama