JPH0478664A - Power boosting steering gear - Google Patents

Abstract

PURPOSE:To prevent the sudden change of steering force by stopping the on-off switching of motor-driven power steering mechanism until steering torque becomes less than the set torque value even when the vehicle speed during the turning motion of a vehicle becomes the set vehicle speed value for on-off switching the motor-driven power steering mechanism. CONSTITUTION:Steering mechanism 4, provided additionally with a torque sensor 10 for detecting the steering torque of a steering wheel 6 and the like, has motor-driven power steering mechanism 8 formed of a motor 12 and a clutch 14, and the motor 12 and the clutch 14 are controlled by a control means 16 on the basis of the output of the torque sensor 10. The control means 16 also receives the vehicle speed state from a vehicle speed sensor 26 and the steering torque state from the torque sensor 10 so as to stop the on-off switching of the motor-driven power steering mechanism 8 until the steering torque becomes less than the prestored set torque value even when the vehicle speed during the turning motion of a vehicle becomes the prestored set vehicle speed value for on-off switching the motor-driven power steering mechanism 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a boost steering system, and more particularly to a boost steering system that can prevent sudden changes in the steering force of a steering wheel during turning of a vehicle. .

[Prior Art] In vehicles, since a human-powered steering device alone causes driver fatigue due to the steering force of the steering wheel, a power steering mechanism is provided that uses another power source to increase the steering force. There are things that exist. This power steering mechanism uses hydraulic pressure, compressed air, electricity, etc. as a power source.

Devices for reducing the steering force in this manner are disclosed, for example, in Japanese Patent Publications No. 53-38850 and Japanese Patent Publication No. 50-7331. The device described in Japanese Patent Publication No. 53-38850 is equipped with a torque detector that detects steering wheel torque, a vehicle speed detector that detects vehicle speed, and a clutch that disconnects the steering wheel shaft and electric motor during high-speed driving, and connects and releases the clutch. By performing this only when the steering wheel torque is zero, the discontinuous feeling when the clutch is engaged and released is eliminated and the feeling is improved.

In addition, the device described in Japanese Patent Publication No. 50-7331 can reduce the steering force by blocking the supply of drive current to the motor or stopping the entire device in case of a failure in the internal circuit. This is to ensure the safety of driving.

In addition, in the electric power steering mechanism, as shown in FIG. It is being switched on and off as the switch is turned on and off.

In the control means for operating the electric power steering mechanism, when the clutch is switched from on to off, as shown in FIG.
The motor output is reduced from time Tl to time T2, for example, 0.6 seconds have elapsed since then.
It gradually decreases until the elapsed time T3, thereby avoiding the occurrence of shock.

In addition, when the clutch is switched from off to on, the motor output is changed to 50% at time Tll, as shown in FIG.
%, and for example, the elapsed time TI of 0.08 seconds
The motor output is gradually increased to 67% of 2 and turned on at 100% at time T12, and the motor output is gradually increased from time Tll to time T13 to avoid the occurrence of shock.

[Problems to be Solved by the Invention] However, as shown in FIG. The power steering mechanism turned off and the steering wheel suddenly became heavy, causing a shock and causing discomfort. On the other hand, if the gradual reduction time is made longer, there is a contradictory disadvantage in that the operating feeling of the electric power steering mechanism deteriorates.

Further, as shown in FIG. 7, the motor current (assist amount) of the electric power steering mechanism may be determined based on the vehicle speed and the value from the torque sensor. Therefore,
When the electric power steering mechanism is turned from on to off or from off to on when the steering torque is large, there is an inconvenience that a shock occurs.

Furthermore, as shown by the broken line in Fig. 7, if the current value relative to the steering torque is reduced by tJX at speeds from on to off and from off to on, the inertia of the motor will conversely cause
When the motor is turned off, the connected motor becomes unconnected.
There is an inconvenience that the steering force of the steering wheel changes suddenly and lightly, causing a shock.

[Object of the invention] Therefore, the object of this invention is to eliminate the above-mentioned disadvantages.
Even if the vehicle speed reaches a set value that causes the electric power steering to be switched on and off while the vehicle is turning, the steering wheel To provide a booster steering device that prevents sudden changes in steering force to avoid the occurrence of shock, and that can be made inexpensive by using an existing system.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a booster steering system that switches an electric power steering mechanism on and off depending on vehicle speed and steering torque. control means is provided for stopping the on/off switching of the electric power steering mechanism until the steering torque becomes less than the set torque value even when the vehicle speed reaches a set vehicle speed value at which the electric power steering mechanism is switched on/off. It is characterized by

[Function] According to the configuration of the present invention, the control means is capable of controlling the steering torque to become less than the set torque value even when the vehicle speed reaches the set vehicle speed value at which the electric power steering mechanism is switched on and off while the vehicle is turning. The electric power steering mechanism is switched on and off until the steering torque reaches the set torque value, and the electric power steering mechanism is switched on and off until the steering torque becomes less than the set torque value, so the steering force of the steering wheel changes rapidly. This can prevent the occurrence of shock.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail and specifically based on the drawings.

1 to 3 show embodiments of this invention. In FIG. 1, 2 is a booster steering device of a vehicle (not shown);
4 is a steering mechanism, 6 is a steering wheel, and 8 is an electric power steering mechanism.

The steering mechanism 4 is connected to a torque sensor 10 that detects the steering torque of the steering wheel 6 and the like.

The electric power steering mechanism 8 is the steering mechanism 4.
The steering wheel includes a motor 12 for operating the steering mechanism 4, and a clutch 14 for switching and driving the motor 12.

The torque sensor 10 and the electric power steering mechanism 8 are in communication with a control means 16 .

This control means 16 includes an ignition key switch 18
The battery 20 is connected via the.

Further, the control means 16 is connected to an alternator 22, an ignition mechanism 24 that outputs an ignition pulse signal, a vehicle speed sensor 26 that detects vehicle speed, and an idle up solenoid 28.

The control means 16 inputs the vehicle speed state from the vehicle speed sensor 26 and the steering torque state from the torque sensor 10, and determines a pre-stored setting for switching the electric power steering mechanism 8 on and off based on the vehicle speed while the vehicle is turning. Even when the vehicle speed reaches the vehicle speed value, ON/OFF switching of the electric power steering mechanism 8 is stopped until the steering torque becomes less than the pre-stored set torque value.

Next, the operation of this embodiment will be explained.

When switching the electric power steering mechanism 8 from the on state to the off state when the vehicle is turning, the electric power steering mechanism 8 is on (step 102), as shown in FIG. In other words, it is determined whether the vehicle speed has exceeded a pre-stored set vehicle speed value at which the electric power steering mechanism 8 is switched off (step 104).

In the case of No in this step 104, the vehicle speed is not equal to or higher than the set vehicle speed value for switching off the electric power steering mechanism 8, so this judgment state is continued.

On the other hand, if YES in step 104,
Since the vehicle speed has exceeded the set vehicle speed value for switching off the electric power steering mechanism 8, next, the torque sensor 1 is turned off.
It is determined whether the value of 0 is less than a specified value, that is, whether the steering torque has become less than a pre-stored set torque value (step 106).

If NO in this step 106, the electric power steering mechanism 8
Since a shock or the like will occur if the clutch 14 is turned off, the process returns to step 104 where the clutch 14 is turned off. That is,
The switching off of the electric power steering mechanism 8 is canceled.

If YES in step 106, the steering torque becomes smaller than the set torque value, and as the clutch 14 is turned off from on, the electric power steering mechanism 8 is turned off from on (step 108).

On the other hand, when switching the electric power steering mechanism 8 from the OFF state to the ON state when the vehicle is turning, the electric power steering mechanism 8 is OFF (step 202), as shown in FIG. In other words, it is determined whether the vehicle speed has become less than a pre-stored set vehicle speed value at which the electric power steering mechanism 8 is switched on (step 204).

In the case of No in this step 204, since the vehicle speed is not less than the set vehicle speed value for switching the electric power steering mechanism 8, this judgment state is continued.

If YES in this step 204, the vehicle speed has become less than the set vehicle speed value for switching on the electric power steering mechanism 8, so next, check whether the value of the torque sensor 10 is below the specified value, that is, the steering torque is stored in advance. It is determined whether the torque has become less than the set torque value (step 20).
6).

If No in this step 206, the electric power steering mechanism 8
Since a shock or the like will occur if the clutch 14 is turned on, the process returns to step 204 without turning off the clutch 14. That is,
The switching on of the electric power steering mechanism 8 is canceled.

If YES in step 206, the steering torque becomes smaller than the set torque value, and the clutch 1
4 from off to on (step 208).

As a result, when the vehicle is turning, the electric power steering mechanism 8 is switched on and off after confirming that the steering torque is sufficiently small. On/off switching of the electric power steering mechanism 8 is canceled, while the electric power steering mechanism 8 is switched on/off when the steering torque is small when the vehicle is traveling in a straight line.
The steering force of the steering wheel 4 does not change suddenly, the occurrence of shock is avoided, and the vehicle can therefore be turned in a predetermined direction.

Furthermore, in this booster steering device 2, an existing system can be used by simply changing the program of the control means 16, and a detection means such as a steering angle sensor is not required, making it possible to reduce the cost.

In this embodiment, in order to prevent the electric power steering mechanism 8 from switching on and off at the halfway point of turning when driving at an 8-way intersection, etc., even if the steering wheel 6 is returned, that is, the steering In order to prevent the electric power steering mechanism 8 from turning on and off immediately even when the wheel 6 is turned quickly, a time lag may be set in the control means 16 to switch the electric power steering mechanism 8 after a predetermined period of time has elapsed. It is possible.

[Effects of the Invention] As is clear from the detailed explanation above, according to the present invention,
A control means for stopping the on/off switching of the electric power steering mechanism even when the vehicle speed reaches a set vehicle speed value at which the electric power steering mechanism is switched on and off until the steering torque becomes less than the set torque value while the vehicle is turning. By providing this, it is possible to prevent sudden changes in the steering force of the steering wheel, thereby avoiding the occurrence of shock, and also to reduce the cost by using an existing system.

[Brief explanation of the drawing]

Figures 1 to 3 show embodiments of the present invention, Figure 1 is a system circuit diagram of the booster steering system, Figure 2 is a flowchart for switching the electric power steering mechanism from on to off, and Figure 3 is an electric power steering mechanism. It is a flowchart when switching a power steering mechanism from off to on. Figures 4 to 7 show an explanation of conventional on/off switching of the electric power steering mechanism, Figure 4 is a time chart for switching on/off depending on vehicle speed, and Figure 5 shows how to switch the electric power steering mechanism from on to off. FIG. 6 is a time chart for switching the electric power steering mechanism from OFF to ON, and FIG. 7 is an explanatory diagram showing the value of motor current determined by vehicle speed and steering torque. In the figure, 2 is a booster steering device, 4 is a steering mechanism, 6 is a steering wheel, 8 is an electric 7-inch power steering mechanism, 10 is a torque sensor, 12 is a motor, 14 is a clutch, 16 is a control means, and 26 is a It is a vehicle speed sensor. Figure Figure

Claims (1)

[Claims] 1. In a booster steering device that switches the electric power steering mechanism on and off depending on vehicle speed and steering torque,
Even if the vehicle speed reaches a set vehicle speed value at which the electric power steering mechanism is switched on and off while the vehicle is turning, the on/off switching of the electric power steering mechanism is stopped until the steering torque becomes less than the set torque value. A boost steering device characterized by comprising a control means for controlling.