JP3494732B2 - Vehicle suspension device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension device.

[0002]

2. Description of the Related Art In order to achieve a high level of ride comfort and maneuverability of a vehicle, the spring constant of the air spring and the damping force of the shock absorber are normally kept in a soft state while the maneuverability during turning is improved. An electronically controlled suspension is known, which is designed to be switched to a hard one in a driving situation where importance is attached to (Mitsubishi Motors Technical Review 199
3 NO.5 “Development of electronically controlled suspension for large buses”
reference).

Among them, in the roll control, an acceleration sensor is provided on the vehicle body in order to detect the lateral acceleration of the vehicle, but the sensor output when the vehicle is stopped depends on the characteristics of the sensor, the mounting accuracy, the leveling error of the air spring, and the like. Since it is not horizontal, some function for correcting the neutral point (horizontal value) of the sensor output is required. Therefore, a method of filtering the sensor output to learn and correct the neutral point is conceivable (Japanese Patent Laid-Open No. 64-32918).

[0004]

However, in a large air suspension type bus, the air spring of the suspension is used to make kneeling (lowering the vehicle height at the front of the vehicle) or ferry boat (the vehicle height of the entire vehicle at the time of boarding). Since the vehicle height is changed variously, such as adjusting the front and rear axle weights, even if the horizontal value of the sensor output is learned and corrected only when the vehicle is stopped, an accurate correction value is not always obtained and proper roll control is performed. Could damage the.

An object of the present invention is to solve such a problem.

[0006]

In the first invention, as shown in FIG. 5, an actuator a for switching suspension characteristics in two or more stages, a means b for detecting a lateral acceleration of a vehicle, and a detection signal based on the detection signal are used. A means c for controlling the actuator for switching the suspension characteristics so as to suppress the roll of the vehicle body, an actuator d for changing the vehicle height, a means e for outputting a command signal for changing the vehicle height based on human operation, Means f for controlling an actuator for changing the vehicle height according to the command signal, means g for learning and correcting the neutral point of the detection signal based on the detection signal of the lateral acceleration,
Based on the correction value, a means h for correcting lateral acceleration as an input signal for roll control, and a command signal for changing the vehicle height
And a means i for canceling the learning correction when the vehicle height is changed .

In the second aspect of the invention, the means g for learning and correcting the neutral point of the lateral acceleration detection signal in FIG. 5 are means j for detecting the vehicle speed, and a lateral acceleration detection signal when the stop state is judged from the detection signal. Means for calculating the average value for a predetermined time, means for obtaining the learning correction value as the neutral point of the lateral acceleration detection signal based on this average value, and the new correction value for the learning correction so far. A means n for rewriting the value is provided.

In the third aspect of the invention, the means m for obtaining the learning correction value shown in the figure uses the weighting factor W for the average value of the lateral acceleration detection signals.
Is calculated by multiplying the learning correction values up to now by a weight of 1-W and adding them.

[0009]

According to the first aspect of the invention, since the lateral acceleration is not learned and corrected when the vehicle height is changed such as by kneeling, a high accuracy of the learning correction value can be obtained. As a result, the roll control based on the detection signal of the lateral acceleration is appropriately performed, and the roll of the vehicle body can be accurately suppressed.

According to the second aspect of the invention, the learning correction of the lateral acceleration is performed on the condition that the vehicle is stopped except when the vehicle height is changed. In this case, the average value of the lateral acceleration detection signals in a predetermined time is calculated, the learning correction value is obtained based on this average value, and the learning correction value up to that point is rewritten with a new correction value.
Therefore, since the learning correction of the lateral acceleration is not performed during traveling or when the vehicle height is changed, an accurate learning correction value can be stably obtained.

According to the third aspect of the present invention, the learning correction value is not the average value of the lateral acceleration detection signals, but the weighting coefficient W is used to add the learning correction values so far by the weight of 1-W. Therefore, even when the vehicle body is tilted when stopped,
The learning correction value does not greatly change from the previous values, and the roll control can be stabilized.

[0012]

1 and 2, 20 is a vehicle body as a sprung system of a vehicle, 1a to 1d are tires as unsprung systems of the vehicle, and air springs 2a to 2f and shock absorbers 7a to 7f are attached to them. Intervened. Although not shown, the shock absorbers 7a to 7f are provided with a damping force variable mechanism (including an actuator) that is switched between two stages, hard and soft, by opening and closing the orifice of the piston.

The air springs 2a to 2f are connected to the air reservoir 3 via leveling valves 4a to 4c for controlling air supply and exhaust so as to maintain a desired vehicle height. Since the rear wheel has one leveling valve 4c, the rear left and right air springs 2c, 2e and 2d, 2f are in communication with each other.
Open / close valves 8a and 8b are provided in the respective pipes.

The sub-tanks 5a to 5d are connected to the air springs 2a to 2f via the switching valves 6a to 6f, respectively. When the opening / closing of the valves 6a to 6f is controlled, the substantial air volume changes, so that the air spring 2a. The spring constant of ~ 2f is switched between two levels (hard and soft). FIG. 1 is an overall system configuration diagram, and FIG. 2 is a configuration diagram on a front wheel side representing a suspension for one wheel.

The vehicle speed sensor 17 for detecting the traveling speed of the vehicle, the lateral acceleration sensor 14 for detecting the lateral acceleration of the vehicle body, and the vertical direction of the vehicle body are provided as the detection means necessary for performing various controls according to the traveling condition of the vehicle. Vertical acceleration sensors 15a and 15b for detecting acceleration (in this case, they are arranged at left and right symmetrical positions with the center of the axle on the front wheel side interposed), a steering angle sensor 11 for detecting the steering angle of the steering wheel, and a braking state of the vehicle. Foot brake switch 12, back lamp switch 16, side brake switch 13, and mode changeover switch 1 for selecting manual control and automatic control
0 is provided.

Here, the lateral acceleration sensor 14 is of a differential transformer type and is composed of a differential transformer type coil on the outer periphery of the bobbin and a magnet. When the ball inside the bobbin moves by inertial force, the voltage of the differential transformer type coil is changed. It fluctuates, and the acceleration is detected from the value. In this case, the neutral point of the sensor output when the vehicle is stopped does not always become horizontal due to the mounting accuracy of the sensor 14 and the leveling error of the air spring, so that the neutral point of the sensor output needs to be learned and corrected as described later. .

The controller 9 controls rolls of the vehicle body, brake dives, pitching and bouncing, etc. based on input signals from these sensors and switches.
Then, a vehicle height changing unit 18 for controlling the leveling valves 4a to 4c of the air springs 2a to 2f is provided outside the vehicle height changing unit 18 for changing the vehicle height in accordance with a change command associated with a manual operation in the driver's cab. For the vehicle height changing unit 18,
The means for instructing the vehicle height change based on human operation may be left outside (driver's seat), and the means for controlling the vehicle height change according to the instruction signal may be housed inside the controller 9.

The functional block configuration of the roll control system of the controller 9 is shown in FIG. 3. A means 31 for input processing the detection signal of the lateral acceleration sensor 14 and an input for processing the detection signal of the vehicle speed sensor 17. Means 32 and means 33 for input-processing the change signal of the vehicle height changing unit 18.
A means 34 for learning and correcting the neutral point (horizontal value) of the lateral acceleration signal when determining the stop state from the vehicle speed signal, and determining whether roll control is necessary while correcting the neutral point (horizontal value) of the lateral acceleration signal with the learning correction value based on the lateral acceleration signal. Means 35, means 36 for outputting a control signal to the switching valves 6a-6f of the air springs 2a-2f based on the determination result, and the shock absorbers 7a-
Means 37 for outputting a control signal to the damping force varying mechanism of 7f
And means 38 for canceling learning correction of lateral acceleration when receiving a vehicle height change signal.

FIG. 4 is a flow chart for explaining the roll control, which is repeatedly executed at a predetermined control cycle. First, after performing various initializations in step 1, the detection signal Gy of the lateral acceleration sensor 14, the detection signal V of the vehicle speed sensor 17, and the change signal H of the vehicle height changing unit 18 are read in step 2, respectively. In step 3, it is determined from the vehicle speed signal V whether or not the vehicle is traveling, and when the vehicle is stopped (V = 0), step 10
Go to.

Since the roll control is performed during traveling, in step 4, the control acceleration signal Gc is calculated from the lateral acceleration detection signal Gy and the learning correction value Go. In step 5, the absolute value of Gc is compared with the control threshold value Gt. If | Gc |> Gt, in steps 6 and 7, the air spring 2a is
The switching valves 6a to 6f of 2f are closed and the damping force varying mechanism of the shock absorbers 7a to 7f is switched to the "hard" state. If | Gc |> Gt is not satisfied, the switching valve 6 of the air springs 2a to 2f is determined in steps 8 and 9.
“A” to “6f” are kept “open”, and the damping force varying mechanisms of the shock absorbers 7a to 7f are kept “soft”.

Since the neutral point (horizontal value) of the lateral acceleration detection signal Gy is learned and corrected while the vehicle is stopped, only when the vehicle height change signal H is not turned on in step 10, the stopped state is continued in steps 11 to 13. Has reached a predetermined time T ₁ (the time required for the shaking of the vehicle body due to the stoppage to subside),
The average value Ga of the lateral acceleration detection signal Gy until the predetermined time T ₂ elapses is calculated.

Then, in step 14, the average value Ga is multiplied by the weighting coefficient W, the learning correction value Go so far is multiplied by 1-W, and a value obtained by adding these is used as a new learning correction value Go to rewrite the memory. When the vehicle height change signal H is ON in step 10, it is determined that the vehicle height is being changed such as kneeling and axle load adjustment, and learning correction of the neutral point of the lateral acceleration sensor 14 is not performed. Return to.

With this configuration, since the lateral acceleration learning correction is not performed while the vehicle is traveling or when the vehicle height is changed, an accurate learning correction value Go is obtained, and the roll control based on the lateral acceleration detection signal Gy. Is appropriately performed, and it becomes possible to accurately suppress the rolling of the vehicle body.

The learning correction value Go is the detection signal Gy of the lateral acceleration.
Since the learning correction value Go is calculated by using the weighting coefficient W in consideration of the weight of 1-W, the average value Ga of
The learning correction value Go does not significantly change from the previous value, and the roll control can be properly stabilized.

If the learning correction when the vehicle height is changed is canceled, the lateral acceleration learning correction may be performed during straight traveling.

[0026]

According to the first aspect of the present invention, an actuator for switching suspension characteristics in two or more steps,
A means for detecting the lateral acceleration of the vehicle, a means for controlling an actuator for switching suspension characteristics so as to suppress the roll of the vehicle body based on the detection signal, an actuator for changing the vehicle height, and a vehicle based on human operation. A means for outputting a command signal for changing the height, a means for controlling an actuator for changing the vehicle height according to the command signal, a means for learning and correcting the neutral point of the detection signal based on the detection signal of the lateral acceleration, and It has means for correcting lateral acceleration as an input signal for roll control based on the correction value and means for canceling learning correction when changing the vehicle height, so learning correction of lateral acceleration is performed when changing vehicle height such as kneeling. Because there is no
High accuracy of the learning correction value can be obtained, and the roll control can be appropriately performed.

According to the second aspect of the present invention, the means for learning and correcting the neutral point of the lateral acceleration detection signal includes means for detecting the vehicle speed and a predetermined time for the lateral acceleration detection signal when the vehicle stop state is determined from the detection signal. Means for calculating the average value at
Since the means for obtaining the learning correction value as the neutral point of the detection signal of the lateral acceleration based on this average value and the means for rewriting the learning correction value so far to the new correction value are provided, the learning correction of the lateral acceleration is performed. Since it is performed under the condition that the vehicle is stopped except when the vehicle height is changed, an accurate learning correction value can be stably obtained.

According to the third aspect of the present invention, the means for obtaining the learning correction value has the weighting coefficient W added to the average value of the lateral acceleration detection signals.
Multiply the learning correction value so far by 1-W weight,
Since the arithmetic processing for adding these is performed, even when the vehicle body is tilted in the stopped state, the learning correction value does not significantly change from the previous value, and stable roll control can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire system showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a suspension for one wheel.

FIG. 3 is a functional block diagram showing a part of a control unit.

FIG. 4 is a flowchart illustrating control contents of a control unit.

FIG. 5 is a diagram corresponding to the claims of the present invention.

[Explanation of symbols]

1a-1d tires 2a-2f Air spring 4a-4c leveling valve 5a-5d sub tank 6a-6f switching valve 7a-7f shock absorber 9 Controller 14 Lateral acceleration sensor 17 vehicle speed sensor 18 Vehicle height change unit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masami Hagiwara Ichichome Ichichome, Ageo City, Saitama Prefecture, Nissan Nissan Diesel Industry Co., Ltd. (56) Reference JP-A-2-95915 (JP, A) JP-A-1 -229709 (JP, A) JP 63-134319 (JP, A) JP 4-339006 (JP, A) JP 64-95923 (JP, A) JP 2-6209 (JP, A) ) JP-A-7-242112 (JP, A) JP-A-4-362409 (JP, A) Actually developed 60-8113 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60G 17/015

Claims (3)

(57) [Claims] 1. An actuator for switching suspension characteristics in two or more stages, a means for detecting a lateral acceleration of a vehicle, and an actuator for switching suspension characteristics so as to suppress rolling of a vehicle body based on the detection signal. Means, an actuator for changing the vehicle height, a means for outputting a command signal for changing the vehicle height based on a human operation, a means for controlling the vehicle height changing actuator according to the command signal, and a lateral acceleration Means for learning and correcting the neutral point of the detection signal based on the detection signal, means for correcting lateral acceleration as an input signal for roll control based on the correction value, and vehicle height change based on a vehicle height change command signal
A means for canceling the learning correction at the time, and a suspension device. 2. A means for learning and correcting a neutral point of a lateral acceleration detection signal, means for detecting a vehicle speed, and calculating an average value of the lateral acceleration detection signals at a predetermined time when a vehicle stop state is judged from the detection signal. Means, means for obtaining a learning correction value as a neutral point of the detection signal of the lateral acceleration based on this average value, and means for rewriting the learning correction value so far to the new correction value The suspension device according to claim 1. 3. A means for obtaining a learning correction value is configured such that an average value of detection signals of lateral acceleration is multiplied by a weighting coefficient W, a learning correction value so far is multiplied by a weight of 1-W, and arithmetic processing is performed to add them. The suspension device according to claim 2, which is performed.