JPS61125965A - Electric power steering device - Google Patents

Abstract

PURPOSE:To secure sufficient power assist at a time of idling by arranging an electric generator, which outputs electric voltage in response to the number of revolution of an engine, separately from an electric charging system so as to assist steering torque by means of an electric power from the generator with the engine idled up. CONSTITUTION:A torque sensor 15 detects the value of torque by a handle. This detected torque value allows a control circuit 24 to be operated, then the control circuit 24 permits electric current from an electric generator 23 of other than an electric charging system, to be controlled in response to the detected torque value in applying to an electric motor 16. Resultantly, the electric motor 16 assists the torque by the handle. The above mentioned generator 23 outputs electric voltage in response to the number of revolution of an engine 20. Simultaneously, an idle-up means 40 is allowed to operate based on the detected torque value permitting the number of revolution of the engine 20 to be idle up. This allows the number of revolution of the generator 23 to be increased permitting its output to be augmented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electric power steering device in which steering torque is assisted by an electric motor.

<Prior Art> Generally, in an electric power steering system in which steering torque is assisted by an electric motor, a battery and a generator (alternator) are used as power supply sources for the electric motor.
is used. Such a generator is driven by an engine, and the amount of power generated varies depending on the engine speed, but the voltage regulator controls the generated voltage, and the battery voltage is adjusted to 12
It is designed to adjust to a constant voltage of V.

In this type of electric power steering system, a high current is required in order to generate the necessary torque with an electric motor using a low-voltage battery as a power supply source, resulting in problems such as motor seizure.

This problem can be significantly improved by providing a generator that outputs a generated voltage according to the engine rotational speed, in addition to the charging system generator, and using this generator as a power supply source for the electric motor.

<Problems to be Solved by the Invention> However, even in the case where a generator is provided separately from the charging system, the generated voltage of the generator is also low during idling when the engine speed is low, so the idling speed decreases. Sometimes there is a limit to the output torque of the electric motor, and when the engine is stopped in an idling state, there is a problem that the assist torque provided by the electric motor is insufficient.

Means for Solving the Problems> The present invention has been made to solve the above-mentioned conventional problems, and as shown in Fig. A generator 23 is provided that outputs a corresponding generated voltage, and this generator 23 is used as a power supply source for the electric motor 16 that assists the steering torque. In addition to controlling the output current supplied to the engine 20, the engine 20 is idled up by an idle up means 40.

<Operation> Therefore, according to the present invention, when the torque sensor 15 detects the steering wheel torque based on the steering wheel operation, the electric motor 1 whose power supply source is the generator 23 which is separate from the charging system is activated.
The electric current supplied to the electric motor 6 is controlled by the control circuit 24, and the electric motor 16 is started with a torque corresponding to the steering wheel torque to assist the steering wheel torque. Also, based on the steering wheel torque from the torque sensor 15, the idle up means 40 increases the rotation speed of the engine 20, thereby increasing the rotation speed of the generator 23 and increasing the output of the generator 23. .

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral O indicates a handle shaft. A steering handle 11 is attached to one end of the handle shaft 10, and a nion shaft 13, which is supported by a gear box 12, is coupled to the other end. The binion shaft 13 is meshed with a rack shaft 14 fitted in the gear box 12, and this rank shaft 14
Although not shown, both ends of the steering wheel are connected to steering wheels via ball joints or the like.

A torque sensor 15 is provided on the handle shaft 10 to detect the handle torque applied to the steering handle 11 and its direction. In addition, an electric motor 16 that assists the steering wheel torque is connected to a gear 17 on the handle shaft 10.
are connected via.

Reference numeral 20 indicates an engine of an automobile, and a first generator 21 is connected to this engine 20 via a belt transmission device.
A battery 22 is connected to this electric machine 21 to constitute a charging system. The generator 2L has a built-in voltage regulator, and this voltage regulator controls the field current flowing through the field coil to control the generated voltage, making it suitable for various electrical equipment regardless of the rotation speed of the engine 20. In addition to supplying sufficient power, the battery 22 is properly charged.

A second generator 23 as a power supply source for the electric motor 16 is also connected to the engine 20 via a belt transmission. The second generator 23 is configured to output a generated voltage according to the rotational speed of the engine 20, and this generated voltage is applied to the control circuit 24. Thus, the control circuit 24 controls the current value supplied to the electric motor 16 according to the torque signal output from the torque sensor 15, and controls the output characteristics of the electric motor 16 with respect to the steering wheel torque as shown in FIG. It looks like this. In addition, Fig. 3 shows the generator 2 when the field current is kept constant.
3 shows the external load characteristics.

A carburetor 31 is connected to the engine 20 via an intake manifold 30, and a throttle valve 32 is disposed in the carburetor 31.

A negative pressure actuator 33 is connected to the throttle valve 32, and the negative pressure actuator 33 rotates the throttle valve 32 in the direction of opening when the rear chamber 33a becomes negative pressure. However, negative pressure actuator 3
The rear chamber 33a of No. 3 is connected to the intake manifold 30 via an electromagnetic switching valve 34. The solenoid of the electromagnetic switching valve 34 is energized by a solenoid drive circuit 35 that is controlled based on the signal from the torque sensor 15, and the switching of the electromagnetic switching valve 34 causes the rear chamber 33a of the negative pressure actuator 33 to be energized. is intake manifold 3
Connected to 0. As a result, the diaphragm of the negative pressure actuator 33 compresses the spring and moves toward the rear chamber 33a, rotating the throttle valve 32 in the opening direction.
The amount of air-fuel mixture supplied to the engine 20 is increased, the engine speed is increased, and the generated voltage of the generator 23 is increased.

The above configuration constitutes an idle-up means 40 that increases the engine output based on the steering wheel torque, as shown in FIG. 4.

In the above-described configuration, when the steering handle 11 is operated, the torque sensor 15 generates a positive or negative output corresponding to the steering wheel torque, which is applied to the control circuit 24 . The control circuit 24 controls the rotation direction of the electric motor 16 based on the output from the torque sensor 15, and also controls the output current of the generator 23 to be applied to the electric motor 16.
The electric motor 16 is driven with an output torque corresponding to the steering wheel torque to assist the steering wheel torque.

In this case, when the output from the torque sensor 15 exceeds a predetermined value, the solenoid drive circuit 35 causes the electromagnetic switching valve 34 to
The solenoid is energized, and the electromagnetic switching valve 34 is switched. As a result, the rear chamber 33a of the negative pressure actuator 33
is communicated with the intake manifold 30, the diaphragm of the negative pressure actuator 33 is displaced against the spring, and operates to open the throttle valve 32. This increases the amount of air-fuel mixture supplied to the engine 20,
The idle speed of the engine 20 is increased.

Therefore, even if the handle 11 is operated when the engine 20 is idling, the idling speed of the engine 20 is increased based on the handle torque, and the output current of the generator 23 is thereby increased. The electric motor 16 can provide the necessary assist force even when the vehicle is in use.

<Effects of the Invention> As described above, the present invention provides, in addition to a charging system generator,
The configuration is equipped with a generator that outputs a generated voltage according to the engine speed, and this generator is used as the power supply source for the electric motor that assists the steering torque, so the electric motor can be started with high voltage and low current. This has the effect of preventing motor seizure and the like, as well as allowing a small motor to obtain the necessary torque.

Moreover, in the present invention, when the handle is operated while the engine is idling, the engine speed is increased to idle and the voltage generated by the generator is increased. It has the effect of giving.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a system diagram showing an electric power steering device, Fig. 2 is a line diagram showing the output torque of the electric motor with respect to the steering torque, and Fig. 3 is a diagram showing the electric motor output torque. FIG. 4 is a diagram showing the engine idling speed relative to the steering wheel torque. 11... Steering handle, 15... Torque sensor, 1
6... Electric motor, 20... Engine, 23...
Generator, 24... Control circuit, 34... Switching valve, 40
...Means for increasing idle.

Claims (1)

[Claims] (1) In an electric power steering system that starts an electric motor based on the steering wheel torque applied to the steering wheel to assist the steering torque, the electric motor is activated based on the steering torque applied to the steering wheel. A generator is provided that outputs a corresponding generated voltage, and this generator is used as a power supply source for the voltage motor. A torque sensor is provided that detects the handle torque, and power is supplied to the electric motor based on the output of the torque sensor. A control circuit is provided to control the output current,
The electric power steering device further includes an idle up means for increasing the engine speed based on the output of the torque sensor.