Measuring and testing – Brake testing – Vehicle installation
Reexamination Certificate
1998-07-13
2001-07-10
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Brake testing
Vehicle installation
Reexamination Certificate
active
06257056
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of inspecting a cornering control mechanism which independently controls right and left brakes at the time of oversteering or understeering of a vehicle such as a motor vehicle, whereby the vehicle is brought closer to neutral steering.
2. Description of the Related Art
The cornering control mechanism has the following arrangement. Namely, signals from a lateral G (gravity) sensor, a yaw rate sensor, a steering angle sensor, and a wheel speed sensor are inputted into a controller. Based on the signals from these sensors, there are computed an angular velocity of revolution (i.e., revolution around the center of turning curvature) and an angular velocity of rotation (i.e., rotation on a vertical axis of rotation of the vehicle). When the angular velocity of rotation has exceeded the angular velocity of revolution, a judgement is made that the vehicle is oversteered and, therefore, a braking force is applied to the wheels on an outer side of cornering by the operation of a brake. When the angular velocity of rotation has become smaller than the angular velocity of revolution, a judgement is made that the vehicle is understeered and, therefore, a braking force is applied to the wheels on the inner side of cornering by the operation of the brake.
The inspection of this kind of cornering control mechanism is conventionally made in an actual running method in which the vehicle actually runs on a test course or in an electronic simulation system in which simulated signals are inputted into a controller to see whether or not the controller outputs an appropriate brake control signals.
The actual running method must depend for its judgement on a driver's driving senses and therefore lacks in reliability. Further, because of the time required for the inspection, it is impossible to perform the inspection on all of the vehicles. In the electronic simulation system, on the other hand, the functions of the controller can be inspected, but an overall inspection including the sensors and the brake cannot be made. This system therefore has a problem in the point of quality guarantee.
In view of the above points, the present invention has an object of providing an inspection method in which the inspection of the cornering control mechanism can be performed on a bench type of testing apparatus by running or driving the vehicle thereon.
SUMMARY OF THE INVENTION
In order to attain the above and other objects, the present invention is a method of inspecting a cornering control mechanism of a vehicle in which a braking force is applied to wheels on an outer side of cornering when the vehicle is oversteered and a braking force is applied to wheels on an inner side of cornering when the vehicle is understeered, said inspection being performed in a state in which each of the wheels is placed on each drum of a bench type of testing apparatus, said method comprising the steps of: driving driving wheels of the vehicle by a driving source of the vehicle in a state in which all of the drums are coupled to each other via respective clutches; releasing the coupling of one of the drums on which one of the left and right driving wheels is mounted, to the other of the drums when a vehicle speed has reached a predetermined speed; detecting subsequent deceleration of said one of the driving wheels and subsequent deceleration of the other of the driving wheels; discriminating whether the cornering control mechanism has operated normally or not based on the deceleration of said one of the driving wheels; discriminating, based on the deceleration of the other of the driving wheels, whether an accelerator has been switched off; and when a discrimination is made that the accelerator has been switched off, prohibiting the discrimination of operation of the cornering control mechanism based on the deceleration of said one of the driving wheels.
In a state in which all of the drums are coupled to each other, idler wheels of the vehicle are driven by the driving wheels via the drums for the driving wheels and those drums for the idler wheels which are coupled to the drums for the driving wheels. As a result, a load is applied to the driving wheels. When the drum for one of the driving wheels is released of coupling to the other drums, the load on said one of the driving wheels is reduced and the rotational speed of said one of the driving wheels is increased. By the operation of a differential gear which is mounted on the vehicle between both the driving wheels, the rotational speed of the other of the driving wheels is reduced. Then, a controller which is mounted on the vehicle judges that the vehicle is in an oversteering state in which an angular velocity of rotation has exceeded an angular velocity of revolution (the angular velocity of revolution is zero when the vehicle is in a straight-running condition). The controller therefore operates the brake of that one of the driving wheels which lies on the outer side of cornering to apply a braking force thereto. Once the braking force is applied to said one of the driving wheels as described above, said one of the driving wheels is decelerated. Based on this deceleration, a discrimination can be made as to whether the cornering control mechanism has operated normally or not.
When the operator releases the pressing down of the accelerator pedal (i.e., switches off the accelerator), said one of the driving wheels is decelerated even if the cornering control mechanism does not operate. Therefore, a wrong discrimination will be made if only the deceleration of said one of the driving wheels is being monitored. It is to be noted here that, when the accelerator is switched off, the deceleration of the other of the driving wheels also becomes large. Therefore, a discrimination can be made as to whether the accelerator has been switched off based on the deceleration of the other of the driving wheels. In the present invention, when the discrimination is made that the accelerator has been switched off, the discrimination of operation of the cornering control mechanism based on the deceleration of said one of the driving wheels is prohibited. A wrong judgement can thus be prevented.
While the accelerator is being switched off, the braking force is sometimes applied to said one of the driving wheels by the operation of the cornering control mechanism. In order to increase the accuracy of the judgement, whether the cornering control mechanism is acceptable or not, it is desired to make it possible to discriminate whether the braking force is applied to said one of the driving wheels or not even while the accelerator is switched off. The deceleration of said one of the driving wheels changes largely on the instant when the braking force is applied. Even when the accelerator is switched off, a discrimination can be made, based on the degree of change in deceleration of said one of the driving wheels, as to whether the braking force is applied or not. However, since the deceleration of said one of the driving wheels also largely changes on the instant when the accelerator is switched off, it is necessary to prohibit the discrimination of operation based on the degree of change in deceleration at the time when the accelerator is switched off. Here, since the deceleration of the other of the driving wheels also largely changes at the time of switching off of the accelerator, the time at which the accelerator is switched off can be discriminated based on the degree of change in the deceleration of the other of the driving wheels. Therefore, by discriminating that the braking force is applied to said one of the driving wheels when a rate of change in the deceleration of the other of the driving wheels is below a first predetermined value and when the rate of change in the deceleration of said one of the driving wheels is above a second predetermined value, the operation of the cornering control mechanism can be accurately discriminated during the period while the accelerator is switched of
Fukamachi Kazuyuki
Maekawa Keiichiro
Shibayama Takao
Armstrong Westerman Hattori McLeland & Naughton LLP
Davis Octavia
Fuller Benjamin R.
Honda Giken Kogyo Kabushiki Kaisha
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