Stabilizer system

1. A stabilizer system for a vehicle, comprising:

a stabilizer device including a stabilizer bar and a switch configured to switch a roll suppressing function of suppressing roll of a body of the vehicle by the stabilizer bar between an effective state in which the roll suppressing function is rendered effective and an ineffective state in which the roll suppressing function is rendered ineffective; and

a controller configured to determine whether a lateral acceleration of the body of the vehicle is greater than a threshold lateral acceleration and to control the switch to render the roll suppressing function effective when the lateral acceleration is greater than the threshold lateral acceleration and to render the roll suppressing function ineffective when the lateral acceleration is not greater than the threshold lateral acceleration,

wherein the controller selectively employs, as a determination lateral acceleration for determining whether the lateral acceleration is greater than the threshold lateral acceleration, a smaller one of an actual lateral acceleration obtained based on detection by a lateral acceleration sensor provided in the vehicle and an estimated lateral acceleration estimated based on a degree of turning of the vehicle without depending on the actual lateral acceleration.

2. The stabilizer system according to claim 1 , wherein the controller employs, as the determination lateral acceleration, a smaller one of the actual lateral acceleration and the estimated lateral acceleration estimated based on a degree of an operation of a steering operating member of the vehicle.

3. The stabilizer system according to claim 1 , wherein the controller employs, as the determination lateral acceleration, a smaller one of the actual lateral acceleration and the estimated lateral acceleration estimated based on an actual yaw rate obtained based on detection by a yaw rate sensor provided in the vehicle.

4. The stabilizer system according to claim 1 , wherein the threshold lateral acceleration is different between when the actual lateral acceleration is employed as the determination lateral acceleration and when the estimated lateral acceleration is employed as the determination lateral acceleration.

5. The stabilizer system according to claim 4 , wherein the threshold lateral acceleration when the actual lateral acceleration is employed as the determination lateral acceleration is less than the threshold lateral acceleration when the estimated lateral acceleration is employed as the determination lateral acceleration.

6. The stabilizer system according to claim 4 , wherein the threshold lateral acceleration when the estimated lateral acceleration is employed as the determination lateral acceleration is less than the threshold lateral acceleration when the actual lateral acceleration is employed as the determination lateral acceleration.

7. The stabilizer system according to claim 1 ,

wherein both ends of the stabilizer bar are respectively connected to a pair of wheel holding portions that respectively hold right and left wheels and that move upward and downward with the corresponding right and left wheels relative to the body of the vehicle,

wherein the stabilizer device includes:

a pair of cylinders which contain a working fluid and each of which is disposed between the body of the vehicle and a corresponding one of a pair of right and left supported portions of the stabilizer bar such that the stabilizer bar is supported by the body of the vehicle at the supported portions, each of the cylinders being configured to extend and contract in accordance with a rebound motion and a bound motion of a corresponding one of the right and left wheels with respect to the body of the vehicle, each of the cylinders including a first fluid chamber whose volume increases in the rebound motion of the corresponding one of the right and left wheels and decreases in the bound motion of the corresponding one of the right and left wheels and a second fluid chamber whose volume decreases in the rebound motion of the corresponding one of the right and left wheels and increases in the bound motion of the corresponding one of the right and left wheels;

a first communication passage through which the first fluid chamber of one of the cylinders and the second fluid chamber of the other of the cylinders communicate with each other;

a second communication passage through which the second fluid chamber of the one of the cylinders and the first fluid chamber of the other of the cylinders communicate with each other;

an inter-passage communication passage through which the first communication passage and the second communication passage communicate with each other; and

an open/close valve functioning as the switch and disposed in the inter-passage communication passage, the open/close valve being configured to open the inter-passage communication passage when placed in a valve open state and to close the inter-passage communication passage when placed in a valve closed state,

wherein the controller controls the open/close valve to selectively establish an inter-passage non-communicating state in which the first communication passage and the second communication passage do not communicate with each other and an inter-passage communicating state in which the first communication passage and the second communication passage communicate with each other, so as to switch the roll suppressing function between the effective state and the ineffective state.

8. The stabilizer system according to claim 1 ,

wherein both ends of the stabilizer bar are connected to one of i) the body of the vehicle and ii) a pair of wheel holding portions that respectively hold right and left wheels and that move upward and downward with the corresponding right and left wheels relative to the body of the vehicle, the stabilizer bar being supported by the other of i) the body of the vehicle and ii) the pair of wheel holding portions,

wherein the stabilizer device includes:

a cylinder disposed between: the one of i) the body of the vehicle and ii) the pair of wheel holding portions; and one of the both ends of the stabilizer bar, the cylinder being configured to extend and contract in accordance with a) a rebound motion of one of the right and left wheels and a bound motion of the other of the right and left wheels and (b) a bound motion of the one of the right and left wheels and a rebound motion of the other of the right and left wheels, the cylinder including a first fluid chamber whose volume increases when the cylinder extends and decreases when the cylinder contracts and a second fluid chamber whose volume decreases when the cylinder extends and increases when the cylinder contracts;

an inter-chamber communication passage through which the first fluid chamber and the second fluid chamber communicate with each other; and

at least one open/close valve functioning as the switch and disposed in the inter-chamber communication passage, each of the at least one open/close valve being configured to open the inter-chamber communication passage when placed in a valve open state and to close the inter-chamber communication passage when placed in a valve closed state;

wherein the controller controls the at least one open/close valve to selectively establish an inter-chamber non-communicating state in which the first fluid chamber and the second fluid chamber do not communicate with each other and an inter-chamber communicating state in which the first fluid chamber and the second fluid chamber communicate with each other, so as to switch the roll suppressing function between the effective state and the ineffective state.