JPH01240368A - Power steering device - Google Patents

Abstract

PURPOSE:To prevent missensing in sensing discontinuity of a car speed sensor by stopping assist to the steering action in case, when the engine is started, the condition in which the car speed is zero and the engine revolving speed is over a reference value has continued for a specified period of time until counting the time for a certain period of time is finished. CONSTITUTION:When an ignition key 7 is turned on an engine is started, a control part 1 judges whether the car speed signal is zero or not from the output of a car speed sensor 2, and if yes, it is judged that the current time is within a certain period of time (approx. 3min) of engine start. If yes, it is judges whether the number of engine revolutions sensed by an engine number-of- revolutions sensor 3 is over a certain level, and if yes, a timer shall be set. When the car speed being zero is sensed even after passage of the set period of time on the is timer, it is judged that the car speed sensor 2 is in failure, and the steering assist is stopped and the fact is stored in a backup memory 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric power steering device installed in an automobile.

[Prior art]

Electric power steering devices installed in automobiles use a motor to assist in the operating force required to steer the automobile, and in such devices, the assisting force for steering operation is adjusted according to the vehicle speed. There is a need to. That is, a large assisting force is required when turning the vehicle stationary while the vehicle is stationary or while running at low speed, but if the assisting force is large while the vehicle is running at high speed, the steering wheels will be operated too much, which is dangerous. For this reason, during high-speed running, the assisting force is reduced or the assisting force is not applied.

In this way, the assist force for steering operation is closely related to the vehicle speed, and the vehicle speed detection signal is an important element.If the signal line of the vehicle speed sensor that detects this is disconnected, the steering operation will be interrupted for safety. A system has been proposed that stops assisting the handling operation (for example, Japanese Utility Model Application Publication No. 156080/1983).

[Problem to be solved by the invention]

By the way, the disconnection of the vehicle speed sensor is detected when the engine speed is above a certain number of revolutions during normal driving and the vehicle speed signal is not obtained for a certain period of time or more. ing. However, when the engine is warmed up immediately after starting, the above conditions are met, resulting in a false detection of a disconnection in the vehicle speed sensor and stopping assisting the steering operation. The time was not carried out.

Therefore, if the vehicle speed sensor is disconnected, for example, if the engine is suddenly started after the engine is started, the disconnection of the vehicle speed sensor will not be detected until the predetermined time has elapsed, and by then the vehicle speed or high speed Even if
Since a detection signal from the vehicle speed sensor cannot be obtained and the vehicle speed is considered to be zero, that is, the vehicle is stopped, the maximum force is applied to assist the steering operation, which is extremely dangerous.

The present invention has been made in view of the above circumstances, and provides a power source that detects a disconnection of the vehicle speed sensor immediately after starting the engine and at the same time as the start of driving without erroneously detecting the disconnection of the vehicle speed sensor, thereby reliably preventing the occurrence of a dangerous situation due to the disconnection of the vehicle speed sensor. The purpose is to provide a steering device.

[Means to solve the problem]

The power steering device according to the present invention adjusts the force for assisting the steering operation of the steering mechanism of the automobile in accordance with the vehicle speed, and when the detected value of the vehicle speed is zero and the detected value of the engine speed is a first value. In a power steering device configured to stop assisting the steering operation when a condition exceeding a reference value continues for a predetermined period of time, the power steering device includes a timer that starts measuring time when the engine starts, and a timer that starts measuring time when the engine starts, and Determine whether or not the detected value of the vehicle speed is zero and the detected value of the engine speed is equal to or higher than a second reference value, which is higher than the first reference value, for a predetermined period of time until the time measurement ends. a determining means for performing the steering operation when the determining means determines that a state in which the detected value of the vehicle speed is zero and the detected value of the engine rotation speed is equal to or higher than the second reference value continues for a predetermined time; a steering assistance stopping means for stopping assistance for the steering operation; a memory for storing information that assistance for the steering operation has been stopped by the steering assistance stopping means; The present invention is characterized by comprising means for stopping assisting the steering operation when the steering operation is stored.

[Effect]

When the engine is started, timing starts, and by the time the fixed time measurement ends, the detected value of the vehicle speed is zero and the detected value of the engine rotation speed is equal to or higher than the second reference value, which is higher than the first reference value. If this continues for a predetermined period of time, assistance in steering operation is stopped.

The fact that this steering operation assistance has been stopped is stored in the memory even if the engine is stopped, and if the above-mentioned content is stored in the memory after the engine is started, then the Assistance in steering operation is stopped without performing determination processing.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is a block diagram showing the configuration of a control system of a power steering device according to the present invention.

An output signal from a vehicle speed sensor 2 that detects the traveling speed of the vehicle is supplied to the input port (at) of the control section 1.

The input boat a2 is provided with an output signal from an engine rotation speed sensor 3 that uses a low-resolution encoder, for example, and detects the rotation speed of the engine.

The input boat a3 is supplied with a detection signal from a torque sensor 4 that detects a rotational force applied to a steering wheel that is interlocked with a steering mechanism (not shown) via a shaft.

On the other hand, a steering motor 5 that performs a steering assistance operation of the steering mechanism is connected to the output capo bl of the control section 1 via a drive circuit (not shown). Depending on the input signal, the output capo-1-b is driven when it is at a high level.

A bank amplifier memory 6 connected to the control unit 1 stores information when the steering motor 5 is stopped due to a disconnection of the detection signal of the vehicle speed sensor 2, as will be described later.

The control unit 1 includes an ignition key 7 for starting the engine.
The bank amplifier memory 6 is directly connected to the battery 8. In other words, the contents stored in the backup memory 6 will not be erased even if the ignition key 7 is turned off, that is, the engine is stopped.

The second section describes the operation details of the control section 1 configured as described above.
This will be explained based on the flowchart shown in the figure. First, when the ignition key 7 is turned on to start the engine and a predetermined voltage is supplied to the control unit 1, the contents of the bank amplifier memory 6 are read out, and the steering operation is assisted by the disconnection of the vehicle speed sensor 2. It is determined whether or not it is stored that it has been stopped (step ■). If the vehicle speed signal is not stored, it is determined whether the vehicle speed signal is zero, that is, whether the vehicle speed signal is zero due to a disconnection of the vehicle speed sensor 2 or whether the vehicle is stopped or the vehicle is running. If is zero, it is determined in step (2) whether the current time is within time T1 after the engine is started. This time T is the time required for the engine to settle from a relatively high rotational speed during warm-up immediately after starting the engine to an idling rotational speed, and is set to, for example, about 3 minutes. If within time T1 after starting the engine, the engine speed is N1.
It is determined whether or not the above is true (step ■). This rotational speed NI is set higher than the high rotational speed during warm-up when the vehicle is stopped.

If the engine speed becomes N1 or more, the timer t is reset, the flag F is set (=1), and the counting of the predetermined time T is started (steps ① to 0). When the engine speed is lower than N, or when the timer t is counting, steering operation assistance control is performed in both steps [phases]. That is, the steering motor 5 is driven in response to the detection signal from the torque sensor 4.

When the timer t finishes timing T, that is, after the engine starts at a vehicle speed of zero, the engine speed is within the time T and the engine speed is higher than the high speed when the engine is warmed up when the vehicle is stopped for a predetermined period of time. (=T) If it continues, it is determined that the vehicle is running, but the vehicle speed is still zero, so it is determined that the vehicle speed sensor 2 is disconnected, and the steering assistance is stopped. The fact that the steering assistance has been stopped is stored in the backup memory 6 (step ①).

[phase]). As a result, even in the case of a sudden start immediately after the engine is started, the disconnection detection of the vehicle speed sensor 2 is started at the same time as the start of travel, and if the disconnection occurs, steering operation assistance is stopped for safety.

On the other hand, if the engine speed does not exceed N8 for a predetermined period of time due to step
, in other words, if the vehicle is not driven until the engine reaches idling speed, proceed to step ■, determine whether the engine speed becomes N2 or higher, and similarly It is determined whether or not this state continues for a predetermined time T in parallel with the steering assistance control in step [phase]. This rotational speed N2 is set to a value lower than the rotational speed NI, but higher than the idling rotational speed.

If the engine rotational speed continues to be N2 or higher for a predetermined period of time, assistance in steering operation is similarly stopped in steps @ and [phase], and this is written in the backup memory 6. In other words, after the engine has stabilized after T1 has elapsed, the engine speed continues to exceed N2 for a predetermined time even though the vehicle speed is zero, so the vehicle is actually running and the vehicle speed sensor 2 is disconnected. It is determined that there is.

Also, if the vehicle speed is not zero in step ■, step ■
controls to assist in normal steering operations.

Now, after the disconnection of the vehicle speed sensor 2 is detected by the above-mentioned control and steering operation assistance is stopped, if the engine is stopped and restarted due to stalling, for example,
That is, if the engine is restarted without repairing the disconnection of the vehicle speed sensor 2 and updating the contents stored in the backup memory 6, the contents of the bank-up memory 6 are first read out in step (2) as described above. As a result, if it is already stored that the assisting of the steering operation has been stopped due to the disconnection, the assisting of the steering operation is immediately stopped in step (2).

〔effect〕

As described above, in the power steering system according to the present invention, even in the case of a sudden start immediately after starting the engine, the disconnection detection of the vehicle speed sensor is started at the same time as the start of driving.
Instead of waiting for the non-detection time set to prevent erroneous detection until the engine stabilizes as in the past, it quickly detects the disconnection of the vehicle speed sensor and stops assisting the steering operation in a short time. Even when the vehicle speed increases, it is possible to prevent the occurrence of a dangerous situation due to excessive turning of the steering wheel.

Furthermore, once a disconnection in the vehicle speed sensor is detected and steering operation assistance is stopped, this fact will be remembered even if the engine is stopped, and if the engine is restarted without the disconnection being repaired, Since steering operation assistance is immediately stopped without the need for time to determine the first disconnection detection, maximum steering operation assistance is applied even in the case of multiple abnormalities such as torque sensor failure. is not given,
The present invention has excellent effects such as improved safety.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of main parts showing the configuration of a power steering device according to the present invention, and FIG. 2 is a flowchart for explaining its operation. 1...Control unit 2...Vehicle speed sensor 3...Engine speed sensor 4...Torque sensor 5...Steering motor 6...Backup memory patent Applicant Koyo Seiko Co., Ltd. Agent Patent attorney Noboru Kono

Claims (1)

[Scope of Claims] 1. A force for assisting a steering operation of a steering mechanism of an automobile is adjusted according to the vehicle speed, and when the detected value of the vehicle speed is zero and the detected value of the engine rotation speed is a first reference value. In a power steering device configured to stop assisting the steering operation when the above state continues for a predetermined period of time, the power steering device includes a timer that starts measuring time when the engine starts, and a timer that starts measuring time when the engine starts; A determination to determine whether or not the detected value of the vehicle speed is zero and the detected value of the engine rotation speed is equal to or higher than a second reference value higher than the first reference value for a predetermined period of time until the time measurement ends. and means for assisting the steering operation when the determining means determines that the detected value of the vehicle speed is zero and the detected value of the engine rotational speed is equal to or higher than the second reference value for a predetermined period of time. a steering assistance stopping means for stopping the steering assistance stopping means; a memory storing information that the assistance for the steering operation has been stopped by the steering assistance stopping means; and a memory storing information that the assistance for the steering operation has been stopped after the engine is started. 1. A power steering device comprising: means for stopping assisting a steering operation when the steering operation is stored.