JPH0659834B2 - Motor drive type power steering control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive type power steering control device for energizing a steering device of an automobile with an auxiliary load by a rotational force of a motor.

[Conventional technology]

Conventionally, this type of motor-driven power steering control device has a structure in which a driving force of a motor is biased to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a reduction gear.

[Problems to be solved by the invention]

However, the conventional motor-driven power steering control device has a drawback that the handle is lightened only on one side when the power element forming the power element part for controlling the electric current flow and direction of the motor is damaged.

The present invention has been made to solve such a problem, and it is possible to prevent the handle from being lightened only on one side when the power element is damaged, which does not involve a significant cost increase and is a highly safe motor-driven power source. The purpose is to obtain a steering control device.

[Means for solving problems]

The motor-driven power steering control device according to the present invention is provided with a control unit that detects the opening of the power element that drives the motor and shuts off the current supplied to the motor.

[Work]

In this invention, when the control unit detects that the power element is open, the control unit cuts off the current supplied from the power element to the motor.

〔Example〕

An embodiment of a motor-driven power steering control device of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the embodiment.

In FIG. 1, reference numeral 1 is a steering wheel that receives a steering rotational force of a driver, and 3 is a torque sensor that outputs an electric signal according to the rotational force applied to the steering wheel 1.

Between the steering wheel 1 and the torque sensor 3, the steering wheel 1 is connected to the first steering shaft 2a via the first steering shaft 2a.
Of the universal joint 4a, and the first universal joint 4a is connected to the second universal joint 4b via the second steering shaft 2b. The second universal joint 4b is connected to the torque sensor 3 via the third steering shaft 2c.

The torque sensor 3 is connected to the speed reducer 16 via the fourth steering shaft 2d. The output of the torque sensor 3 is the steering torque measuring means 9 in the control unit 9.
a (described later with reference to FIG. 2).

The speed reducer 16 is inserted between the electromagnetic clutch 15 and the pinion shaft 5. The pinion shaft 5 meshes with the rack tooth portion 6 a of the rack shaft 6.

Both ends of the rack shaft 6 are connected to pole joints 8a and 8b via tie rods 7a and 7b, respectively.

On the other hand, 12 is a vehicle battery. The negative electrode of the battery 12 is grounded, and the positive electrode is connected to the control unit 9 via the key switch 13 and directly connected to the control unit 9.

The output of the vehicle speed sensor 10 is also input to the control unit 9. Control unit 9
Controls the drive of the motor 14 and the electromagnetic clutch 15.

The electromagnetic clutch 15 can connect or disconnect mechanical connection between the motor 14 and the speed reducer 16 according to the instruction of the control unit 9.

FIG. 2 is a configuration diagram showing a specific configuration of the control unit 9 of the embodiment shown in FIG. In FIG. 2,
Reference numeral 9a is a steering torque measuring means for measuring the steering torque by the input from the torque sensor 3, and 9b is a vehicle speed measuring means for measuring the vehicle speed.

The steering torque measuring means 9a and the vehicle speed measuring means 9b are connected in cascade, and the output of the vehicle speed measuring means 9b is sent to the motor current measuring means 9c.

This current measuring means 9c is provided by a current sensor 9j described later,
The current flowing through the motor 14 is measured.

The motor current storage means 9d stores and holds the steering torque and the current value of the motor 14 corresponding to the vehicle speed.

Normally, the value stored and held in the motor current storage means 9d is determined as the value read by the motor current determination means 9e, and when the output of the power element open defect determination means 9f in the next stage is an open output, it is set to zero. The motor current determining means 9e determines the current of the motor 14.

The power element open failure determination means 9f is a power for controlling the energization current and the energization direction to the motor 14 when the motor current measurement value by the motor current measurement means 9c is zero in response to the energization current flow instruction to the motor 14. It is determined that the power elements 9i _{1 to} 9i ₄ forming the element portion 9i are open and output.

The electromagnetic clutch control means 9g controls to connect or disconnect the electromagnetic clutch 15 depending on at least the condition determined by the vehicle speed and the output condition of the power element open defect determination means 9f.

Based on the output of the motor current determination means 9e, the power element section control means 9h instructs the power element section 9i to drive the motor 14
ON to control the energizing direction to the
It is designed to give instructions for turning off.

The power element portion 9i based on the output of the power element unit control means 9h, are formed of a first to fourth power element 9i ₁ ～9I ₄ to control the direction and the current value of the current of the motor 14.

The value of the current flowing through the power element portion 9i is the current sensor 9j.
I try to measure at.

A voltage corresponding to the current flowing through the current sensor 9j is applied to the motor current measuring means 9c.

Next, the operation of the above embodiment will be described with reference to FIGS. 3 is a control characteristic diagram of steering torque versus motor current, FIG. 4 is a control characteristic diagram of vehicle speed versus motor current and electromagnetic clutch applied voltage, and FIG. 5 is a flow chart showing a control program of the control unit 9.

First, at the time of starting the engine, step S1 in FIG.
Initialize with, and turn on the key switch 13,
The electromagnetic clutch 15 is turned on, and the motor 14 and the speed reducer 16 are mechanically connected.

In this state, when the driver applies a turning force to the steering wheel 1,
The control unit 9 controls the current of the motor 14 as shown in FIG. 3, and the steering torque measuring means 9a receives the output of the torque sensor 3 and measures the steering torque in step S2.

In FIG. 3, when the steering torque is increased to the right, a
At this point, the motor 14 is turned on, and in order to reduce the influence of the inertia of the motor 14 and the mechanical system, the motor current I _OF
(2 to 10 A) A current is passed and the current sensor 9
The motor current measuring means 9c measures the motor current I _MS from the current flowing in j (step S4).

Further, the steering torque is increased and the motor current is linearly increased with respect to the steering torque from the point b, and 100% is obtained at the point c.
It becomes an electric current.

On the contrary, when the steering torque is reduced and the steering torque is reduced from the point c, the motor current is reduced to a motor current value of I _{OF at} the point b.

Further, when the torque decreases to point a, the motor 14 is turned off. In this case, almost the same control is performed even in the leftward direction.

The relationship between the transmission torque and the motor current is proportional. Therefore, when the torque increases in FIG. 3, the motor 14 turns on at the point a and the motor current I _OF flows.

Further, when the torque is increased, the current of the motor 14 is gradually increased from the point b, so the output torque to the speed reducer 16 is gradually increased, and the output torque to the reducer 16 is increased according to the driver's force applied to the steering wheel 1. Auxiliary torque is electromagnetic clutch 1
5, the reducer 16, and the pinion shaft 5 through the rack tooth portion 6
tell a.

Therefore, the handle 1 becomes lighter. The above is the description of the stop operation of the vehicle of the present invention.

Next, when the vehicle is in a running state, the vehicle speed measuring means 9b measures the output of the vehicle speed sensor 10 in step S3,
In step S4, the motor current is measured, and as shown in FIG. 4, the motor current determination means 9e reads out the current I _MI previously held in the motor current memory holding means 9d according to the steering torque and the vehicle speed in step S5. The motor current is controlled by this current I _MI .

The value of the current I _MI takes a value according to only the steering torque up to the vehicle speed at the point d, and a value corresponding to the steering torque after the point d,
It is reduced to a value obtained by multiplying the damping factor according to the vehicle speed, and after the vehicle speed at point e (vehicle speed: assisted vehicle speed V ₂ ), a constant value I _OF is set in order to reduce the influence of the inertia of the mechanical system.

Next, the vehicle speed is f point {vehicle speed = assist cutoff vehicle speed V ₁ (V ₁ >
V ₂ )}, both the motor current and the electromagnetic clutch applied voltage EV become zero, and the motor 14 and the reducer 16
Will disengage, so for the driver turning the steering wheel 1,
Steering without auxiliary load bias.

However, in the conventional device, if the power elements 9i _{1 to} 9i ₄ forming the power element portion 9i are damaged, the handle 1
There was a drawback that only one side of it was light and dangerous.

Therefore, in this invention, when the motor current detected by the current sensor 9j is zero in step S7 when the motor current is energized, the power element open defect determination means 9f determines that the power element is open.

When the motor current instruction value is zero, the process proceeds from step S6 to step S8, and when the vehicle speed V is higher than the assist cutoff vehicle speed V ₁ , that is, V> V ₁ , the motor is controlled by the power element control means 9h at step S9. The current is set to zero, and the electromagnetic clutch control means 9g is set in step S10.
Thus, the voltage applied to the electromagnetic clutch 15 is shut off, and the auxiliary load is not energized. Then, in step S11, the motor current instruction value I _M is stored in I _MO .

If the motor current instruction value is not zero in step S6, the process proceeds to step S7, and this step S7
If the motor current is zero, it is determined that the power element is open, and steps S9 to S11 are performed.

Further, if the vehicle speed V> V ₁ in step S8, the vehicle speed V is higher than the assist decrease vehicle speed V _{2 in} step S12, that is, if V> V ₂ , the motor current output I _{M is set} to I _OF in step S13, and the step is performed. In step S14, the electromagnetic clutch control means 9g controls the coupling of the electromagnetic clutch 15, and the process of step S11 is performed.

If the vehicle speed is not V> V ₂ in step S12, the motor current output I _{M is set} to I _M1 in step S15, and the processes of steps S14 and S11 are performed.

〔The invention's effect〕

As described above, according to the present invention, by changing the control program of the control unit, the opening of the power element is detected and the motor current is shut off. Therefore, when the power element is damaged, only one side of the handle is lightened. It can be changed only, and the safety can be improved without a large cost up.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the construction of an embodiment of the motor-driven power steering control device of the present invention, and FIG. 2 is a diagram showing the concrete construction of the control unit of the embodiment of FIG. FIG. 3 is a control characteristic diagram of steering torque vs. motor current for explaining the above embodiment, FIG. 4 is a control characteristic diagram of vehicle speed vs. motor current and electromagnetic clutch applied voltage, and FIG. 5 is a control program of the above embodiment. It is a flow chart. 1 ... Steering wheel, 3 ... Torque sensor, 9 ... Control unit, 9a ... Steering torque measuring means, 9b ... Vehicle speed measuring means, 9c ... Motor current measuring means,
9d ... Motor current storage means, 9e ... Motor current determination means, 9f ... Power element open defect determination means, 9g
...... Electromagnetic clutch control means, 9h ...... Power element section control means, 9i ...... Power element section, 10 ...... Vehicle speed sensor, 1
2 ... battery, 14 ... motor, 15 ... electromagnetic clutch, 16 ... reducer. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A torque sensor for detecting a turning force of a steering wheel of a vehicle, a vehicle speed sensor for detecting a vehicle speed, a motor for supplying an auxiliary torque to a steering system which is supplied from an on-vehicle battery, and an energization current and an energization of this motor. A power element that controls the direction, and the power element that controls the power element according to the signals of the torque sensor and the vehicle speed sensor, and forms the power element if the motor current is zero when the motor current is energized. And a control unit that outputs a control output that cuts off the power element section when the motor drive type power steering control apparatus is opened. 2. The control unit includes a power element section for controlling a current value and a current flowing direction to the motor,
A sensor that is inserted in series with the power element unit to detect the energization current to the motor, a motor current measuring unit that measures the energization current to the motor by the current sensor, and an energization command to the motor. When the motor current measured by the motor current measuring means is zero, the power element open defect determining means for determining the power element as an open defect and the output condition of the power element open defect determining means 2. The motor-driven power steering control device according to claim 1, further comprising a power element section control means for outputting a control output that cuts off the power element of.