JPS63184571A - Vehicle speed sensitive power steering device - Google Patents

Abstract

PURPOSE:To ensure proper steering force even during low speed driving, by estimating current vehicle speed based on an engine rotation and deceleration, and controlling an actuator for varying the steering force based on the estimated vehicle speed upon occurrence of abnormality in a vehicle speed sensor. CONSTITUTION:When a vehicle is being driven, an output signal from a vehicle speed sensor 10 is taken into CPU24 so as to control a solenoid valve 14 according to an output current level operated according to the vehicle speed thus producing steering force corresponding to the vehicle speed. If it is judged that the vehicle speed is zero, it is judged whether a vehicle speed signal being fed from the vehicle speed sensor 10 is zero. If it is judged that the engine rotation detected through an engine rotation detector 20 is higher than a setting level and the gear position detected through a gear position detector 22 is in parking position or a position other than neutral position, it is judged that the vehicle speed sensor 10 is abnormal. Upon judgement of abnormality, vehicle speed is estimated based on an engine rotation and deceleration so as to control a solenoid valve 14 according to said estimated vehicle speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vehicle speed sensitive power steering device, and in particular to a vehicle speed sensitive power steering device that ensures optimal steering force even when a signal from a vehicle speed sensor that detects vehicle speed is abnormal. The present invention relates to a type power steering device.

[Conventional technology]

Power steering devices are used for the purpose of reducing steering force, but if the steering force is lightened when the vehicle is running at high speeds in the same way as when it is stationary, the steering stability during high-speed running will deteriorate. It is a danger.

Therefore, in a normal power steering device, the steering force is normally controlled so that it becomes heavier as the vehicle speed increases.

This type of power steering device includes, for example, a vehicle speed sensitive power steering device as shown in FIG. This vehicle speed adjustment power steering device controls the drive current of a solenoid valve 14, which is a variable steering force actuator, using a power steering computer (P/S computer) 12 based on a vehicle speed signal from a vehicle speed sensor 10, thereby controlling the steering gear. box 16
The hydraulic pump 18 controls the hydraulic pressure sent into the steering wheel, and as the vehicle speed increases, the assist i is decreased and the steering force is changed.

However, if the vehicle speed sensor 1O malfunctions or the wire harness connecting the vehicle speed sensor 10 and the P/S computer 12 is disconnected, and the vehicle speed signal is no longer input to the P/S computer 12, There was a problem in that the vehicle speed was determined to be O, and even when the vehicle was traveling at high speed, the steering force at the time of steering was reduced.

Therefore, in order to solve this problem, two vehicle speed sensors are installed, and if signals are output alternately from these vehicle speed sensors, normal steering force control is performed as if the vehicle speed signal is normal, and only one vehicle speed sensor is used. It has been proposed that if the vehicle speed signal is not output, it is assumed that the vehicle speed signal is abnormal, and the steering force is increased to be safer (Japanese Patent Laid-Open No. 5
6-97110).

Further, a means for detecting an abnormality in the vehicle speed signal and a means for detecting the running of the vehicle are provided, and the steering force is fixed to a value that is determined by signals from these means when the vehicle speed signal is abnormal and the vehicle is running. A control system has been proposed (Japanese Utility Model Application Publication No. 114369/1983).

[Problem that the invention seeks to solve]

However, in conventional vehicle speed-sensitive power steering devices, the steering force is fixed to a safe value so that the steering force increases when the vehicle speed signal is abnormal, but the vehicle speed signal is abnormal when the vehicle is running at low speed. Even in this case, there is a problem in that the steering force is similarly controlled to be heavy, resulting in a heavy burden on the driver.

The present invention has been made to solve the above problems, and is a vehicle speed sensitive power steering device that estimates the current vehicle speed when the vehicle speed signal is abnormal and ensures appropriate steering force even when driving at low speeds. The purpose is to serve (.

[Means for solving problems]

In order to achieve the above object, the present invention provides a vehicle speed sensitive power steering device that controls a variable steering force actuator using a signal from a vehicle speed sensor, which includes an abnormality determination means for determining an abnormality in a vehicle speed sensor signal, and an engine rotation speed and deceleration. vehicle speed estimating means for estimating the current vehicle speed of the vehicle based on the ratio; and a variable steering force actuator based on the estimated vehicle speed estimated by the vehicle speed estimating means when the vehicle speed sensor signal is determined to be abnormal by the abnormality determining means. and a control means for controlling.

[Operation] According to the present invention, when the abnormality determination means determines that the vehicle speed sensor signal is abnormal, the vehicle speed estimation means estimates the current vehicle speed based on the engine rotation speed and the reduction ratio, and the estimated vehicle speed Since the variable steering force actuator is controlled based on the 2. This makes it possible to prevent the risk of the vehicle shifting, and also to ensure appropriate steering force when driving at low speeds and when stopped.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to a concave surface.

In this embodiment, the present invention is applied to the vehicle speed sensitive power steering device shown in FIG. 1, and the same components as in FIG. 1 are given the same reference numerals.

As shown in FIG. 2, the P/S computer 12 includes a central processing unit (CPU) 24, a read-only memory (
ROM) 26, random access memory (RAM)
28, an input boat 30, an output boat 32, and a bus 34 such as a data bus or a control bus that connects these. A vehicle speed sensor 10 is connected to the input boat 30 via a pulse shaping circuit 36 and an amplifier circuit 3B. For example, as shown in the figure, this vehicle speed sensor 10 is constructed by disposing a reed switch IOB near a rotor magnet IOA that is rotated by a speedometer cable and has protrusions at regular intervals on its circumference. The rotation of this rotor magnet 10A causes the reed switch I to
Because the magnetic flux passing through the OB changes, the reed switch IOB
turns on and off. This on-off frequency is detected as a vehicle speed signal. Further, an engine rotation speed detector 20 is connected to the human-powered boat 30 via a pulse shaping circuit 40 and an amplifier circuit 42 . This engine speed detector 2
For example, as shown in the figure, the pickup 20B is arranged in the vicinity of a signal rotor 20A that is rotated by a distributor shaft and has projections at regular intervals on its circumference. This rotation of the signal rotor 2OA causes an AC voltage to be generated in the pickup 20B, and the frequency of the generated AC voltage is detected as an engine rotation speed signal. Furthermore, a transmission gear position detector 22 is connected to the input port 30 . This transmission gear position detector 22 is 5. For example, in the case of an electronically controlled automatic transmission, the gear position can be detected by a combination of on and off states of two shift control solenoid valves. The output boat 32 has
A coil 14A of a solenoid valve 14, which is a variable steering force actuator, is connected via a digital-analog (D/A) converter 44 and a voltage-current converter 46.

The operation of the vehicle noise response type power steering configured as described above will be explained based on the flowcharts shown in FIGS. 3(A) and 3(B).

First, in step 100, the vehicle speed is initialized, in step 102, the vehicle speed ■ is read from the vehicle speed sensor 10, and in step 104, it is determined whether or not the vehicle speed V read in step 102 is not Ok m/h. If the vehicle speed ■ is not Ok m/h, that is, if the vehicle speed signal is input from the vehicle speed sensor 10 to the P/S computer 12 via the wire harness, an output current according to the vehicle speed V is calculated in step 106,
In step 10B, the output current calculated in step 106 is output to the solenoid valve 14, and a steering force corresponding to the vehicle speed V can be obtained. and step 10
It will be moved to 2.

If the vehicle speed ■ is determined to be Ok m/h in step 104, a subroutine is executed in step 110 to determine whether the vehicle speed signal from the vehicle speed sensor 10 is abnormal.

As shown in FIG. 3(B), this subroutine reads the engine speed n from the engine speed detector 20 in step 120, and in step 122, the engine speed n read in step 120 is determined in advance. It is determined whether or not the set rotation speed (for example, idling rotation speed) is larger than the stored rotation speed. If the engine rotation speed n is greater than the set rotation speed N0, the gear position of the transmission is read from the transmission gear position detector 22 in step 124, and it is determined in step 126 whether the gear position is other than parking or neutral. be done. Engine rotation speed n is set rotation speed N
If it is greater than 0 and the gear position is determined to be other than parking or neutral, the vehicle speed signal from the vehicle speed sensor 10 is abnormal because the vehicle speed is Ok m/h even though the vehicle is running. In step 130, a flag f, which is set when the vehicle speed signal is abnormal, is set to 1.

If the engine speed n is less than or equal to the set rotation speed N, or if the gear position is in parking or neutral, the vehicle speed signal abnormality flag r is reset. If the vehicle speed signal from the vehicle speed sensor 10 is not manually input, it is determined that the vehicle speed signal is abnormal. And next step 1
! In step 2, it is determined whether the vehicle speed signal abnormality flag f is 1 or not. If the vehicle speed signal abnormality flag f is not set to 1, the process moves to step 106, and the vehicle speed is set to OK.
The output current based on m/h is calculated and step 1
The output current calculated in step 08 is output to the solenoid.

In other words, the steering force is the lightest when the vehicle is stationary.

If the vehicle speed signal abnormality flag r is set to 1, in step 114, the estimated vehicle speed is calculated from the following equation (1) based on the current engine speed n, total reduction ratio P, and tire diameter R. Ru.

■, -nP-R・π・6o (1) Then, in step 106, the above estimated vehicle speed ■.

An output current is calculated based on , and the output current calculated in step 10B is output to the solenoid.

With the above control routine, if an abnormality occurs in the vehicle speed signal while the vehicle is running, the vehicle speed can be estimated based on the engine speed and reduction ratio, and an appropriate steering force can be obtained. It is possible to prevent a sudden change to the lowest value equivalent to deferment.

Furthermore, it is possible to prevent malfunctions such as when the vehicle is stopped or traveling at low speeds, where the vehicle speed sensor is mistakenly determined to be abnormal and the stationary steering force is fixed at a heavy value.

In this embodiment, a microcomputer is used to perform control using software, but similar control can be performed using only hardware using a logic circuit.

[Effects of the Invention] As explained above, according to the present invention, the current vehicle speed is estimated when the vehicle speed sensor signal is determined to be abnormal, and the variable steering force actuator is controlled based on this estimated vehicle speed. , it is possible to secure an appropriate steering force similar to normal control in which the vehicle speed sensor signal is not abnormal.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a vehicle speed sensitive power steering device, FIG. 2 is a block diagram showing a vehicle speed sensitive power steering device according to an embodiment of the present invention, and FIG. 3 (A)
, (B) is a flowchart showing a control routine. DESCRIPTION OF SYMBOLS 10... Vehicle speed sensor, 12... P/S computer, 14... Solenoid pulp, 20... Engine rotation speed detector, 22... Transmission gear position detector.

Claims (1)

[Claims] (1) In a vehicle speed sensitive power steering device that controls a variable steering force actuator using a signal from a vehicle speed sensor, there is an abnormality determining means for determining an abnormality in the vehicle speed sensor signal, and a current state of the vehicle based on the engine rotation speed and reduction ratio. a vehicle speed estimating means for estimating a vehicle speed; and a control means for controlling a variable steering force actuator based on the estimated vehicle speed estimated by the vehicle speed estimating means when the vehicle speed sensor signal is determined to be abnormal by the abnormality determining means. A vehicle speed sensitive power steering device characterized by the following: