JPH0597039A - Motor-operated power steering device - Google Patents

Abstract

PURPOSE:To prevent the swing of a car body because of steering being too light during a power pattern by mounting a motor-operated power steering device on an A/T vehicle capable selecting a shift pattern of two modes of the one being a power mode and the other being an economy mode. CONSTITUTION:A motor-operated power steering device comprises a torque sensor 53 to detect steering torque of a steering handle 51, a car speed sensor 54, and a controller 10 to control the motor current of a motor 56 according to output values from both sensors 53 and 54. When a power shift is effected in a steering direction answering to steering torque by means of an output from the motor 56, the controller 10 decides a shift pattern by means of an output from a mode switch to select the shift pattern of the automatic transmission of a vehicle and decides a command current value to the motor 56 according to the decided shift pattern, steering torque, and a car speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus, and more specifically, in an automobile, controlling the output of an assist motor (electric motor) according to the output of a torque sensor for detecting steering torque, The present invention relates to an electric power steering apparatus that performs power assist according to steering torque by the motor.

[0002]

2. Description of the Related Art Conventionally, in an automobile, in order to reduce the steering wheel operation during steering, the motor current value of the assist motor is increased or decreased or turned on or off according to the steering torque and the vehicle speed. A relatively large number of so-called vehicle speed-sensitive electric power steering devices that perform power assist in the steering direction according to the steering torque have been developed and put into practical use.

FIG. 7 shows a simplified structure of an electric power steering apparatus of this type. In this figure, the steering torque input to the steering wheel 51 can be detected by a torque sensor 53 attached to a steering shaft 52, which is a rotating shaft of the steering wheel 51.
Further, the output of the torque sensor 53 and the output of the vehicle speed sensor 54 are the controller 6 that controls the assist motor 56.
It is designed to be input to 0. Further, although not shown here, the controller 60 is actually
A pulse for an ignition signal is input from an ignition circuit (not shown).

The rotational force of the assist motor 56 is transmitted to the reduction gear mechanism 57 via the electromagnetic clutch 55 and to the steering gear portion 58 via the steering shaft 52. On the other hand, the steering torque of the steering wheel 51 is also transmitted to the steering gear portion 58 via the steering shaft 52. This steering gear section 5
8 is normally provided in the central portion of a tie rod 59 connected to the left and right front wheels 61, 62, and the steering shaft 52
Of the tie rod 59 is converted into a left-right reciprocating motion, such as a rack and pinion mechanism. Then, the transmitted rotative force of the assist motor 56 and steering torque of the steering handle 51 drive the tie rod 59 left and right, and the left and right front wheels 61,
62 is steered via a knuckle arm (not shown). In this figure, reference numeral 63 indicates a battery as a power source.

With such a configuration, the torque sensor 5
3, the controller 60 according to the measured value of the vehicle speed sensor 54
Control to increase or decrease the motor current of the assist motor 56 or to turn it on or off to perform the required power assist, and when the vehicle is traveling at low speed, the auxiliary steering force is increased to enable light steering. The auxiliary steering force is gradually reduced as the vehicle speed increases, and manual steering is performed at a certain speed or more to obtain stable steering performance.

[0006]

In an automatic transmission vehicle (hereinafter referred to as "AT vehicle"), a power / economy changeover switch, which is a two-mode shift pattern selection switch operated by a driver, is used. There are some economy patterns to choose from. That is, when traveling normally, economy mode is selected to ensure quiet and smooth driving with economical driving, and strong driving such as traveling in mountainous areas, high-speed overtaking acceleration with plenty of room, and sports traveling. When power is needed, select a power pattern and switch the map of shift timing (shift timing) to increase the vehicle speed for shifting to prolong the acceleration time. Is made possible.

When the conventional electric power steering device is mounted on the AT vehicle capable of selecting the power / economy, the auxiliary power corresponding to the vehicle speed and the steering torque is selected even when the power pattern is selected, which is the same as when the economy pattern is selected. Since the steering force is applied, the steering becomes too light and the vehicle body tends to be unstable, which may cause anxiety to the driver.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art.
To provide an electric power steering device capable of preventing the inconvenience that the steering is too light when the power pattern is selected and the vehicle body wobbles when mounted on an A / T vehicle capable of selecting a two-mode economy shift pattern. is there.

[0009]

In order to achieve the above-mentioned object, according to the present invention, a torque sensor for detecting a steering torque of a steering wheel, a vehicle speed sensor for detecting a vehicle speed, and an output value of both the sensors are provided. A control unit for an electric power steering apparatus configured to increase / decrease a motor current of an assist motor or to control on / off of the assist motor, and to perform power assist in a steering direction according to a steering torque by an output of the assist motor. In addition, a mode switch for selecting a shift pattern of the automatic transmission of the vehicle is provided, and the control unit has a shift pattern determination function of determining the shift pattern based on the output signal of the mode switch, and the determined shift pattern and steering torque. And a target current determination function for determining the command current value of the assist motor according to the vehicle speed. It adopts a configuration that.

[0010]

The shift pattern determination function of the control unit determines the shift pattern of the automatic transmission, the shift pattern determined by the target current determination function of the control unit, the steering torque from the torque sensor, and the vehicle speed from the vehicle speed sensor. The command current value of the assist motor is determined in accordance with. As a result, the motor current value of the assist motor is controlled according to the shift pattern.

[0011]

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. Here, the same reference numerals are used for the same components as those of the above-mentioned conventional example, and the configuration will be simplified or omitted.

As shown in FIG. 1, this embodiment has a structure similar to that of the above-described conventional example as a whole, but instead of the controller 60 as a controller, the controller 1
0 is used and a mode switch (power / economy switching) for instructing the controller 10 to select the two-mode shift pattern of the automatic transmission to the A / T controller 30 which is a control device for the automatic transmission of the vehicle. This is characterized in that the switch) 1 is provided side by side. Other configurations are the same as those of the conventional example described above.

FIG. 2 shows the configuration of the control system in this embodiment. In FIG. 2, the controller 10
The output signals of the torque sensor 53, the vehicle speed sensor 54, and the mode switch 1 are input to the CPU 11 via an input circuit (not shown). The torque sensor 53 detects a twist angle (amount) of a torsion bar (not shown) provided on the steering shaft 52, and outputs a voltage signal corresponding to the twist angle. The torque sensor 53 outputs two types of output signals, a main output and a sub output, and the values of these output signals are usually the same. In the case where the variable resistor (not shown) constituting the device wears over time, the values of the two deviate from each other, whereby the CPU 11 of the controller 10 determines whether the torque sensor 53 is abnormal. The vehicle speed sensor 54 is used for a speedometer and outputs a pulse signal corresponding to the vehicle speed.

The mode switch 1 is a switch for selecting a power pattern and an economy pattern, which are two modes of a shift pattern of an automatic transmission (automatic transmission) (not shown) of the vehicle, and the output of this mode switch. Is A / T controller 3
By being sent to 0, the A / T controller 30 performs the shift control with the shift pattern selected according to the vehicle speed and the throttle opening. At this time, when the power pattern is selected, the vehicle speed for shifting is set to a high speed, the acceleration time is lengthened, and a large driving force is obtained, as described above. Further, the controller 10 has
An ignition signal from an ignition circuit (not shown) is input.

On the other hand, an assist motor 56 and an electromagnetic clutch 55 are connected to the output side of the controller 10. The current value and forward / reverse rotation of the assist motor 56 are controlled by the controller 10, and the electromagnetic clutch 55 is connected to the controller 1.
"ON" / "OFF" is controlled by 0, whereby the assist motor 56 and the reduction gear mechanism 57 are intermittently connected. Further, the controller 10 detects an abnormality of the torque sensor 53 or other abnormality and outputs a diagnosis signal to an external display device (not shown).

Next, the main control operation of the controller 10 will be described with reference to the flowchart showing the control program of FIG.

When an ignition switch (not shown) is turned "ON" at the time of starting the engine, this control program is started. Although not shown in FIG. 3, at the same time when this control program starts, the controller 10
Then, a predetermined initial setting is performed. That is, when an engine (not shown) is started, an ignition signal is input from an ignition circuit (not shown) to the CPU 11 via an input circuit (not shown) of the controller 10, and in the CPU 11,
By inputting this ignition signal, a clutch-on signal is output to the electromagnetic clutch 55. As a result, the assist motor 5
6 is connected to the deceleration mechanism 57 so that power assist is possible.

After starting the control program, the controller 10
The CPU 11 therein reads the vehicle speed from the vehicle speed sensor 54 (step S101) and determines whether the vehicle speed is 40 km / h or less (step S102). If the vehicle speed exceeds 40 km / h, there is no need for power assist, so the assist motor 56 is stopped and the electromagnetic clutch 55 is set to "OFF" (motor / clutch OFF processing routine). ) (Step S108). On the other hand, the vehicle speed is 40 km / h
In the following cases, the steering torque value of the steering wheel 51 is read from the torque sensor 53 (step S10).
3).

Next, the CPU 11 determines whether or not the power pattern is selected as the shift pattern by the output of the mode switch 1 (step S10).
4). When the power pattern is not selected, that is, when the economy pattern is selected, C
In the PU 11, the economy corresponding to the vehicle speed and the steering wheel torque value read in steps S101 and S103 from the steering wheel torque-motor current map as shown in FIG. 4 stored in advance in the internal memory 12 (see FIG. 2). The motor current value at the time of the pattern (shown by the solid line in FIG. 4) is read (S106). On the other hand, when the power pattern is selected in step S104, the steering wheel torque-motor current map as shown in FIG. 4 stored in advance in the internal memory 12 is read in steps S101 and S103. The motor current value (shown by the dotted line in FIG. 4) at the power pattern corresponding to the vehicle speed and the steering torque value of the steering wheel is read (S10).
5).

Next, in the CPU 11, step S107
In step S107, the motor current of the assist motor 56 is controlled according to the motor current value read in step S106 or S105 (S107). As a result, the required power assist is performed by the assist motor 56.

Then, the CPU 11 executes step S10.
In either case of S7 and S108, step S1
Returning to 01, the control operation similar to the above is repeated.

According to the first embodiment described above, the mode switch 1 is provided side by side with the controller 10, and the controller 10 depends on the vehicle speed, the steering torque of the steering wheel, and the shift pattern of the automatic transmission selected by the mode switch 1. Since the current value of the assist motor 56 is controlled so as to change the motor current value, the power assist force during the power pattern and the economy pattern is not constant, and the motor current value during the economy pattern is not constant. Is high and the motor current value is controlled to be low during the power pattern, the steering handle 51 becomes heavier during the power pattern, and the steering handle 51 is selected during mountainous traveling or sports traveling in which the power pattern is selected. Is too light and causes the car to wander Can be avoided, it is possible to give a feeling of moderate steering force is a sense of security and sports driving to the driver by that you will need. Further, since the mode switch (power / economy changeover switch) 1 which is originally equipped in the A / T vehicle can be connected to the controller 10 and the control program of the controller 10 can be simply changed, the cost increase hardly occurs. There are also advantages.

The steering wheel steering torque-motor current map is limited to that which sets the motor current values for the economy pattern and the power pattern for each vehicle speed without changing the vehicle speed range as shown in FIG. Instead of this, for example, a map in which the motor current value is set by changing the vehicle speed range as shown in FIG. 5 may be used.

[0024]

[Second Embodiment] Next, a second embodiment of the present invention will be described.
This embodiment has the same configuration as the first embodiment described above, but the method for setting the motor current of the controller 10 is as follows.
It is different from the first embodiment.

That is, in this embodiment, in the internal memory 12 of the CPU 11 of the controller 10, a steering wheel steering torque-motor current map in the economy pattern shown by the solid line in FIG. 4 and a predetermined correction constant k (where k < The value of 1) is stored in advance.

Next, the control operation of the controller 10 in this case will be described with reference to the flowchart of FIG.

When an ignition switch (not shown) is turned "ON" at the time of starting the engine, this control program is started. At the same time when this control program is started, although not shown in FIG.
Then, the same initial setting as in the first embodiment is performed.

After starting the control program, the controller 10
The CPU 11 therein reads the vehicle speed from the vehicle speed sensor 54 (step S201) and determines whether the vehicle speed is 40 km / h or less (step S202). When the vehicle speed exceeds 40 km / h, there is no need for power assist, so the assist motor 56 is stopped and the electromagnetic clutch 55 is turned “OFF” (motor / clutch OFF processing routine). ) (Step S208). On the other hand, the vehicle speed is 40 km / h
In the following cases, the steering torque value of the steering wheel 51 is read from the torque sensor 53 (step S20).
3).

Subsequently, the CPU 11 reads out the motor current value IM corresponding to the vehicle speed and the torque from the internal memory 12 (S204), and then judges whether or not the power pattern is selected by the output of the mode switch 1 (S20).
5). If the power pattern is not selected, that is, the economy pattern is selected, CP
In U11, the process proceeds to step S207 and step S20.
According to the motor current value IM read in step 4, the motor current of the assist motor 56 is controlled. As a result, the required power assist is performed by the assist motor 56.

On the other hand, when the power pattern is selected in step S205, the CPU 11 calculates the corrected motor current ground IMP by multiplying the motor current value IM read in step S204 by the conversion constant k. Then, (S206), the current value of the assist motor 56 is controlled so as to reach the calculated motor current value (S207).
As a result, the required power assist is performed by the assist motor 56.

Then, in the CPU 11, step S20
In either case of S7 or S208, step S2
Returning to 01, the control operation similar to the above is repeated.

According to the second embodiment described above, the value of the conversion constant k is set so that k <1.
In response to this, the motor current becomes smaller and the handle becomes heavier. Therefore, according to the second embodiment, the same effect as that of the first embodiment can be obtained, and the steering wheel torque-motor current map for each shift pattern as shown in FIG. 4 or 5 needs to be stored in the memory. Therefore, the capacity of the memory can be reduced accordingly, and the assist force can be easily adjusted by changing the conversion constant k.

[0033]

As described above, according to the present invention,
The shift pattern determination function of the control unit determines the shift pattern of the automatic transmission, and the command current value of the assist motor is determined according to the shift pattern, the steering torque, and the vehicle speed determined by the target current determination function of the control unit. Therefore, it is possible to control the motor current value of the assist motor according to the shift pattern, and set the motor current value to be high when the power pattern is selected and to be low when the economy pattern is selected. When the power pattern is selected, the steering handle becomes heavier, and the inconvenience that the steering handle is too light and the vehicle body wanders when driving in mountains or sports where the power pattern is selected can be avoided. It requires strength, so the driver feels secure and is driving sports. It is possible to provide a superior electric power steering apparatus unprecedented that Iringu can provide.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system in the embodiment of FIG.

FIG. 3 is a flowchart showing a main control program of the controller of FIG.

4 is a diagram showing an example of a steering wheel steering torque-motor current map stored in the internal memory of FIG. 2. FIG.

FIG. 5 is a diagram showing another example of a steering wheel steering torque-motor current map.

FIG. 6 is a flowchart showing a main control program of a controller according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1 Mode Switch 10 Controller as Control Unit 51 Steering Handle 53 Torque Sensor 54 Vehicle Speed Sensor 56 Assist Motor

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[Procedure amendment]

[Submission date] November 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

[Operation] Automatic change by the shift pattern judgment function of the control unit
The shift pattern of the speed machine is determined, and the command current value of the assist motor is determined according to the shift pattern determined by the target current determination function of the control unit, the steering torque from the torque sensor, and the vehicle speed from the vehicle speed sensor. It As a result, the motor current value of the assist motor is controlled according to the shift pattern.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

On the other hand, when the power pattern is selected in step S205, the CPU 11 calculates the corrected motor current value IMP by multiplying the motor current value IM read in step S204 by the conversion constant k. Then, (S206), the current value of the assist motor 56 is controlled so as to reach the calculated motor current value (S207).
As a result, the required power assist is performed by the assist motor 56.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0033

[Correction method] Change

[Correction content]

[0033]

As described above, according to the present invention,
The shift pattern determination function of the control unit determines the shift pattern of the automatic transmission , and the command current value of the assist motor is determined according to the shift pattern, steering torque, and vehicle speed determined by the target current determination function of the control unit. Therefore, it is possible to control the motor current value of the assist motor according to the shift pattern, and set the motor current value to be high when the power pattern is selected and to be low when the economy pattern is selected. When the power pattern is selected, the steering wheel becomes heavier, and the inconvenience that the steering wheel is too light and the vehicle body wanders when driving in mountains or sports where the power pattern is selected can be avoided. It requires strength, so the driver feels secure and is driving sports. It is possible to provide a superior electric power steering apparatus unprecedented that Iringu can provide.

Claims (1)

[Claims] 1. A torque sensor for detecting a steering torque of a steering handle, a vehicle speed sensor for detecting a vehicle speed,
A control unit for increasing / decreasing the motor current of the assist motor or for on / off control according to the output values of the both sensors, and performing power assist in the steering direction according to the steering torque by the output of the assist motor. In the electric power steering apparatus, the control unit is provided with a mode switch for selecting a shift pattern of the automatic transmission of the vehicle, and the control unit determines the shift pattern based on the output signal of the mode switch. An electric power steering apparatus having a function and a target current determining function for determining a command current value of the assist motor according to the determined shift pattern, steering torque, and vehicle speed.