JPH04260807A - Roll rigidity controlling device - Google Patents

Abstract

PURPOSE:To provide a roll rigidity controlling device with which a driver is easier to predict an action of a vehicle even in a counter steer operation or the like. CONSTITUTION:For a roll rigidity controlling means 2 for controlling the roll rigidity of at least either of front and rear wheels to be changeable by actuation control to a roll rigidity changing means 1, distribution of the roll rigidity for the front wheels to the rear wheels is determined corresponding to a turning radius of a vehicle computed based on a lateral gravity (G) of the vehicle and a car speed at a turning radius detecting means 5, and a command is outputted to the roll rigidity changing means 1 corresponding to the distribution of the roll rigidity. The distribution of the roll rigidity is determined corresponding to the turning radius in a counter steer operation or the like, thereby a driver is easier to predict an action of the vehicle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll stiffness control device for controlling the roll stiffness of a suspension.

0002

2. Description of the Related Art Generally, the steering characteristics of a vehicle are set to be so-called understeer characteristics, with emphasis placed on running stability of the vehicle when the steering angle is small, that is, when the turning radius is large or when the vehicle is traveling straight. However, if the understeer characteristics are too strong, the turning performance of the vehicle decreases, so when the steering angle is large, that is, when the turning radius is small, it is difficult to obtain steering characteristics that match the driver's intentions. Therefore, a technology has been proposed that achieves both the running stability of the vehicle when traveling straight or when the turning radius is large, and the turning performance of the vehicle when the turning radius is small, by controlling the roll stiffness of the vehicle.

For example, Japanese Patent Laid-Open No. 59-73312 discloses that a steering angle sensor for detecting a steering angle and a shock absorber capable of changing damping force for at least one of the front wheels and the rear wheels are provided, When the steering wheel is not being steered, the ratio of the front wheel damping force to the rear wheel damping force is made larger than when the steering wheel is being steered, while when the steering wheel is being steered, the ratio of the front wheel damping force to the rear wheel damping force is smaller than when the steering wheel is not being steered. A technology has been disclosed.

In general, if the ratio of the front wheel damping force to the rear wheel damping force is increased and the roll stiffness distribution from the front wheels to the rear wheels is increased, the steering characteristics of the vehicle will become understeer, and the front wheel damping force will be reduced by the rear wheel side damping force. If the ratio to the side damping force is made small and the roll stiffness distribution is made small, the steering characteristics of the vehicle will become oversteer, so according to the above technology, when the steering wheel is not being steered, the steering characteristics of the vehicle will be understeer, thereby improving the running stability of the vehicle. At the same time, by weakening the understeer characteristic when steering the steering wheel, it is possible to improve the turning performance of the vehicle during steering.

[0005]

SUMMARY OF THE INVENTION In such conventional roll stiffness control devices, the roll stiffness distribution is changed in accordance with the steering angle. Therefore, if the driver performs a so-called countersteer operation or a steering wheel return operation while the vehicle is turning with a certain turning radius, the roll stiffness distribution changes due to the change in the steering angle, and the steering Since the characteristics change, it may be difficult for the driver to predict the behavior of the vehicle and drive the vehicle as intended.

The present invention provides a roll stiffness control device that allows a driver to easily predict the behavior of a vehicle and drive the vehicle as intended even when performing a countersteering operation or turning the steering wheel back. That is the issue.

[0007]

[Means for solving the problem] In order to solve the above problem,
In the present invention, as shown in the conceptual diagram of the claims in FIG. Lateral G detection means 3 for detecting lateral G of the vehicle, and vehicle speed detection means 4 for detecting vehicle speed.
and a turning radius detection means 5 which calculates the turning radius of the vehicle from the lateral G and vehicle speed, and the roll stiffness control means 2 distributes the roll stiffness between the front wheels and the rear wheels when the turning radius is large compared to when it is small. is large, and a command is output to the roll stiffness changing means 1 to make the roll stiffness distribution of the front wheels to the rear wheels smaller when the turning radius is small than when it is large.

[0008]

[Operation] The turning radius detecting means 5 detects the turning radius of the vehicle according to the lateral G from the lateral G detecting means 3 and the vehicle speed from the vehicle speed detecting means 4. The roll stiffness detecting means 2 determines the roll stiffness distribution between the front wheels and the rear wheels according to the turning radius, and outputs a command to the roll stiffness changing means 1 according to the roll stiffness distribution.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 2 is an overall view showing the configuration of one embodiment of the present invention, taking a rear wheel drive vehicle as an example. In the figure, 11 is an engine, and the output of the engine 11 is transmitted to a differential 14 via a transmission 12 and a propeller shaft 13, and further transmitted to rear wheels 17, 18 via drive shafts 15, 16. Further, 19 and 20 are front wheels.

Hydraulic power cylinders 21, 22, 23, and 24 are provided between the vehicle body (not shown) and front wheels 17, 18 or rear wheels 15, 16, respectively.

25 is an external hydraulic power source, and the external hydraulic power source 2
The hydraulic oil from 5 is supplied to the roll stiffness control valves 26, 27, 2.
Hydraulic power cylinders 21, 22, 23 via 8, 29
, 24. Here, roll stiffness control valve 2
6, 27, 28, 29 are hydraulic power cylinders 21, 22
, 23, 24, and by changing the oil pressure in the hydraulic power cylinders 21, 22, 23, 24, the roll rigidity can be changed.

As described above, the hydraulic power cylinders 21, 22, 2
3 and 24, an external hydraulic power source 25, and roll stiffness control valves 26, 27, 28, and 29 constitute roll stiffness changing means.

Reference numeral 30 denotes a lateral G sensor as lateral G detecting means for detecting lateral G of the vehicle, and 31 denotes a vehicle speed sensor as vehicle speed detecting means for detecting vehicle speed.

Reference numeral 32 denotes a control unit as roll rigidity control means and turning radius control means. FIG. 3 shows a flowchart of the control operation executed by the control unit 32. Here, the operation of this embodiment will be explained with reference to FIG.

First, the control unit 32 receives the lateral G signal YG from the lateral G sensor 30 and the vehicle speed sensor 31.
A vehicle speed signal V is input (step S1), and a turning radius R of the vehicle is calculated according to these signals (step
2). Next, the control unit 32 determines roll stiffness distribution between the front wheels 19 and 20 and the rear wheels 17 and 18 according to the turning radius R based on the characteristics shown in FIG. 4 (step S3). Then, a command is outputted to the roll stiffness control valves 26, 27, 28, and 29 according to the roll stiffness distribution (step S4).

[0016] When the turning radius R is large, step S3
, the roll rigidity of the front wheels 19 and 20 is large, and the rear wheel 17
, 18 side is determined to be small. Step S4
Since the roll stiffness control valves 26, 27, 28, and 29 are operated to achieve the roll stiffness, the front wheels 19
, 20 side hydraulic power cylinders 21, 22 rise, and the hydraulic power cylinders 23, 24 on the rear wheels 17, 18 side increase.
oil pressure decreases. Therefore, the roll stiffness on the front wheels 19 and 20 side is large, and the roll stiffness on the rear wheels 17 and 18 side is small, the steering characteristic becomes understeer, and the running stability of the vehicle is improved.

On the other hand, when the turning radius R is small, it is determined in step S3 that the roll stiffness of the front wheels 19 and 20 is small and the roll stiffness of the rear wheels 17 and 18 is large. In step S4, the roll rigidity control valves 26, 27, 28, 29 are operated to achieve the roll rigidity, so the oil pressure of the hydraulic power cylinders 21, 22 on the front wheels 19, 20 side decreases, and the rear wheels 17, 18 side hydraulic power cylinder 23
, 24 oil pressure increases. Therefore, the roll stiffness on the front wheels 19, 20 side becomes small, and the roll stiffness on the rear wheels 17, 18 side becomes large, and the understeer characteristic is weakened or the steering characteristic becomes weak oversteer, and the turning performance of the vehicle is improved. .

[0018] Therefore, to explain changes in the steering characteristics of a vehicle using an example of when the vehicle is cornering, at the beginning of a turn, as the turning radius R decreases, there is a transition from understeer to oversteer. This improves vehicle behavior as intended by the driver. During a turn, for example, a weak oversteer is maintained according to the turning radius R,
Even when the driver performs a countersteering operation or turns the steering wheel back, the roll stiffness distribution does not change. At the end of the turn, as the turning radius R increases, there is a transition from weak oversteer to understeer, which improves the running stability of the vehicle.

As described above, in this embodiment, the roll stiffness distribution is determined according to the turning radius of the vehicle. Therefore, even if the driver performs a countersteering operation or a steering wheel return operation while the vehicle is turning with a certain turning radius, the roll stiffness distribution does not change due to changes in the steering angle, and the steering characteristics Since no change occurs, the driver can easily predict the behavior of the vehicle and drive the vehicle as intended.

In this example, the steering characteristics of the vehicle were changed by controlling the roll stiffness of the front wheels and the rear wheels, but as shown in FIG. The steering characteristics of the vehicle may be changed by making the roll stiffness of the wheels variable, or by keeping the roll stiffness of the rear wheels constant and making the roll stiffness of the front wheels variable, as shown in FIG. .

Further, in this embodiment, an example was shown in which the present invention is applied to a vehicle in which the roll rigidity can be changed by controlling the oil pressure in the hydraulic power cylinders 21, 22, 23, 24, but the conventional technology As shown in the above, there are vehicles in which the roll rigidity can be changed by changing the damping force of the shock absorber, and roll rigidity can be changed by changing the spring constant as disclosed in JP-A-59-73310, for example. Even if the present invention is applied to a vehicle in which the roll rigidity can be changed by changing the torsional rigidity of the stabilizer as disclosed in Japanese Patent Application Laid-Open No. 60-29317, the same result as in this embodiment can be obtained. effect can be obtained.

[0022]

Effects of the Invention As described above, in the roll stiffness control device according to the present invention, the lateral G
a detection means, a vehicle speed detection means for detecting the vehicle speed, and the lateral G
and a turning radius detection means for calculating a turning radius of the vehicle from the vehicle speed and the turning radius, and the roll stiffness control means distributes roll stiffness to the front wheels and rear wheels larger when the turning radius is large than when it is small, and the turning radius When is small, a command is output to the roll stiffness changing means to make the roll stiffness distribution of the front wheels to the rear wheels smaller than when it is large. Therefore, even if the driver countersteers or turns the steering wheel back while the vehicle is turning with a certain turning radius, the roll stiffness distribution does not change due to changes in the steering angle, and the steering Since no change in characteristics occurs, the driver can easily predict the behavior of the vehicle and drive the vehicle as intended.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims showing a roll stiffness control device of the present invention.

FIG. 2 is an overall diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing control steps in the controller.

FIG. 4 is a characteristic diagram showing the roll stiffness of the front wheels and the rear wheels according to the turning radius.

FIG. 5 is a characteristic diagram showing the roll stiffness of the front wheel side and the rear wheel side according to the turning radius.

FIG. 6 is a characteristic diagram showing the roll stiffness of the front wheel side and the rear wheel side according to the turning radius.

[Explanation of symbols]

1 Roll rigidity changing means 2 Roll rigidity control device 3 Lateral G detection means 4 Vehicle speed detection means 5 Turning radius detection means

Claims (1)

[Claims] 1. A vehicle equipped with a roll stiffness control means for variably controlling the roll stiffness of at least one of the front and rear wheels by controlling the operation of a roll stiffness change means, wherein the lateral G of the vehicle is
The roll stiffness control means includes a lateral G detecting means for detecting a vehicle speed, a vehicle speed detecting means for detecting a vehicle speed, and a turning radius detecting means for calculating a turning radius of the vehicle from the lateral G and the vehicle speed. When the turning radius is large, the roll stiffness distribution between the front wheels and the rear wheels is made larger than when the turning radius is small, and when the turning radius is small, a command is output to the roll stiffness changing means to make the roll stiffness distribution between the front wheels and the rear wheels smaller than when it is large. A roll stiffness control device characterized by: