JP2864474B2 - Electric power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to steering using an electric motor.
Electric power stage that generates auxiliary torque with a power booster
Alling equipmentToRelated. [0002] 2. Description of the Related Art A conventional electric power steering apparatus is
A steering force booster powered by an electric motor
Computer unit (MCU) and motor drive
Control means, provided on the steering wheel.
The steering torque and the steering rotation direction are detected and detected.
PWM control by the control means based on the signal
This generates an auxiliary torque in the electric motor,
To reduce A motor driving circuit for driving a motor
Consists of four transistors that make up a bridge circuit.
Two functions to control the rotation direction of the motor and supply power
Having. In the above bridge circuit, the input terminals are connected to the power supply.
While the output terminals are connected to the motor,
The base of each transistor is a microcomputer unit.
Connected to the output port of the [0004] Then, the microcomputer unit
A pair of opposing sets of bridge circuits are controlled by control signals.
By driving the transistor, the motor is PWM controlled
I control [0005] SUMMARY OF THE INVENTION Electric power stearin
Device uses a microcomputer for advanced control.
By implementing this, high steering response and smooth steering
Rudder feelingTo. However, conventional electric power
The motor drive circuit in the water steering device is 2 KHz
Drive the motor at the frequency of
Noise, parasitic vibration noise,
Or, because it is located near the foot of the passenger compartment,
The generated noise travels through the vehicle body into the vehicle interior,
Through the steering shaft and steering wheel of the water steering device.
In the cabin, and the noise generated by the motor
The sound is based on 2KHz, so the engine
Compared to the noise frequency of the noise source
Higher frequency can cause driver discomfort
It also hinders a smoother steering feel.
Was. In addition, electric power steering devices are
Unlike hydraulic power steering devices,
There is no return power loss of the hydraulic pump that is driven more constantly,
Apply the required amount of power when needed by operating the steering wheel
Power saving system, which improves vehicle fuel efficiency.
Has contributed. However, the bridge circuit of the motor drive circuit
The bipolar transistor that composes
Low current amplification factor, use Darlington connection
And the saturation voltage between the collector and emitter increases,
Lecter loss increases, which increases power loss and saves power.
There is a problem that hinders the force effect. Especially when used in vehicles
Is the saturation voltage because the on-board battery voltage is generally 12V.
The higher the pressure, the lower the actual voltage acting on the motor
As a result, the steering power of the electric power steering system is reduced.
This lowers the ability, which is not preferable. [0007] Further, a bipolar transistor is used.
When driving a bridge circuit,
Since the current amplification factor for the large current of the
The drive input impedance of the ridge circuit can be so high
Power saving because it does not require a large drive current
In addition, it reduces the effect.
The drive circuit for operation becomes large, resulting in high cost, etc.
There are issues. The present invention has been made in order to solve such a problem.
The purpose was electric power stearin
The motor drive circuit that drives the motor of the
A bridge circuit composed of field effect transistors.
Connect the power supply between the input terminals of the bridge circuit of
Connect a motor between them, and connect each field-effect transistor to a microphone.
Out of audible frequency range output from computer unit
Drive control based on the PWM signal or control signal of
And the electric power steering system including the electric motor.
Resonance sound in the audible frequency range by PWM drive or
Eliminates the generation of parasitic vibration noise and electrically drives the battery voltage
It is used effectively for machine drive, and the drive circuit is downsized.
Driving efficiency, that is, smooth steering feeling and saving labor
Electric power with high power effect and high steering power reduction ability
An object of the present invention is to provide a steering device. [0009] [MEANS FOR SOLVING THE PROBLEMS]
Claim 1For carsElectric power steering device
soIs the motor drive circuitIs an n-channel typeField effect tiger
A bridge circuit using transistors.
Connect the power supply between the input terminals of the road and the motor between the output terminals.
connection,Generates auxiliary torque in one rotation direction from the motor
If you want toOpposite sides of the bridge circuit
A set ofn-channel typeField effect transistor
The high potential side of the power supplyN-channel type connected toElectric field effect
When a transistor is turned on via a booster circuit,
Low power side of power supplyN-channel type connected toElectric field effect
Transistor driven by a PWM signal outside the audio frequency range
LetGenerates an auxiliary torque from the motor in the other rotational direction.
When making the bridge circuit, the opposite sides of the bridge circuit facing each other
Another set of n-channel field effect transistors
Of which, an n-channel electric field connected to the high potential side of the power supply
When the effect transistor is turned on via the booster circuit
N-channel type electric field both connected to the low potential side of the power supply
Effect transistor driven by a PWM signal outside the audio frequency range
MoveIt is characterized by the following. [0010] The electric power steering device is an electric motor drive.
In the motion circuit,n-channel typeUsing a field effect transistor
High-potential side of the power supplyN connected to
Channel typeThe field effect transistor is connected via a booster circuit
Driven onAndLow potential side of power supplyN channels connected to
Le typeField effect transistorButPWM outside the audible frequency range
Driven by signalIsYou. Therefore, conventional electric power
The resonance sound based on 2 kHz that the aligning device has
Raw vibration sound is transmitted from the vehicle body and the steering wheel, and
One digit higher than the noise frequency of existing noise sources such as
No driver discomfort due to high frequencies
And the smooth steering feel
Disappears. Also, the bridge circuit of the motor drive circuit is
And pair with each otherDirectionA pair of opposite sidesOr another set of n
Channel typeOf the field-effect transistors,
Place sideN-channel type connected toField effect transistor
Is turned on via the booster circuit,
The voltage between the source and the source can be reduced to about 1.0V.
Electric power steering system
Bipolar tiger that constitutes the bridge circuit of the machine drive circuit
Collector and emitter by Darlington connection of transistor
Drop the saturation voltage between 1.5V and 30% or more
Can be. Thus, the actual voltage acting on the motor
Of the electric power steering system
The ability to improve the power reduction ability and the collector
Power (power
Power) loss can be reduced and power saving effect can be enhanced. Sa
In addition, it is necessary to increase the input impedance of the drive circuit.
And drive current can be reduced.
Power effect can be enhanced. According to claim 2For carsElectric power stay
Alling equipmentThe n-channel type according to claim 1electric field
N-channel enhancement type effect transistor
It is characterized by using a field effect transistor. The electric power steering apparatus has n channels.
Using a tunnel enhancement field effect transistor
So, for example, the p-channel enhancement type
By comparison, the voltage between the drain and source is reduced to about 1/2
Battery voltage can be used effectively to drive the motor.
To reduce the steering force of the electric power steering system.
Can be improved. In addition, between drain and source
Motor drive circuit
Can be reduced in size. According to claim 3For carsElectric power stay
Alling equipmentsoIs the motor drive circuitIs an n-channel type
A bridge circuit using field effect transistors is provided.
Connect the power supply between the input terminals of the bridge circuit of
Connect the motor in between,Auxiliary in one rotation direction from motor
When generating torque,Bridge circuit of each other
A pair of opposing opposite sidesn-channel typeField effect tiger
Out of the transistorN channels connected to the high potential side of the power supply
Is driven through a booster circuit.
And the set of n-channel field effect transistors
Out ofAt least onen-channel typeField effect tiger
Drive the transistor with a PWM signal outside the audible frequency range,
When the motor generates auxiliary torque in the other rotational direction
In this case, the opposite sides of the bridge circuit are opposite to each other.
Out of a set of n-channel field effect transistors
N-channel field effect transformer connected to the high potential side of the source
Driving the transistor through a booster circuit, and
Less of the set of n-channel field effect transistors
Hear one n-channel field effect transistor
Drive with PWM signal out of frequency rangeCharacterized by
You. The electric power steering device is an electric motor drive.
In the motion circuit,n-channel typeUsing a field effect transistor
Bridge circuit, facing each other of the bridge circuit
A pair on the opposite sideOr another set of n-channel typeField effect
At least one of the transistorsn-channel type
PWM signal out of audible frequency range when field effect transistor
The electric power steering including the electric motor
In the audio frequency range by PWM drive in a streaming device
Prevent noise or parasitic vibration noise, and
The working actual voltage can be higher, electric power
The ability to reduce the steering force of the steering device can be increased
You. In addition, like the conventional electric power steering device,
The direction of rotation torque of the motor during the return operation of the handle
And the rotation direction of the motor will not match, preventing smooth operation.
Smooth steering wheel without harm
Forward and return operations. [0017] DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention is attached.
This will be described below with reference to the drawings. FIG. 1 shows an electric motor according to the present invention.
1 is an overall configuration diagram of a power steering device. Figure 1
And the electric power steering device has an input shaft 1,
Speed detector 2, steering torque detector 3, rack shaft 4, baud
Lurisaccurating nut (ball screw) 5, electric
Machine 7, microcomputer unit 8, motor drive circuit
And a power supply circuit 9A. One end of the input shaft 1 is a universal (not shown)
Connected to the steering wheel via a joint,
A pinion gear 1b is integrally attached to the other end.
I have. Also, shafts are provided at both ends of the pinion gear 1b of the input shaft 1.
The pinion holder 12 is removed via the receivers 10a and 11a.
It is attached. The pinion holder 12 has a cylindrical plate 10
And 11 and the strut 13 connecting these together
And the cylindrical plates 10 and 11 are eccentric from the center
It is provided on bearings 10a and 11a. Also a pinion
・ The holder 12 is mounted on the rack
While the cylindrical plate 11 is rotating.
One end of the torsion bar 15 is fixed to the heart.
The other end of the torsion bar 15 is fixed to the rack case.
ing. Further, the cylindrical plate 11 is eccentric from the center of rotation.
Pin 11b is protruded at the position
Is a non-magnetic material having a cylindrical magnetic material 16a at the end.
The moving core 16 is fixed. This movable iron core 16
The cylindrical coil part 17 fixed integrally to the back case
It is loosely inserted so as to be able to move in the axial direction.
And a differential transformer. Therefore, the pinion
As the holder 12 rotates, the displacement of the
It is converted to axial displacement, and this axial displacement is used as an electrical signal.
Output from the differential transformer. The rack shaft 4 is, as shown in FIG.
1b, and the rotational displacement of the input shaft 1 is
It is converted to directional displacement. Both ends of rack shaft 4 are shown
Ball joints, tie rods and knuckles
And change the steering of the wheels. Here, a load acts on the rack shaft 4,
When the load is large, the pinion 1 b
It rotates around the meshing part. For example, input shaft 1 with an arrow
When a torque is applied in the direction of X and rotated, the torque
The torsion bar 15 is twisted according to the size of
The holder 12 is rotated in the direction of arrow Y. At this time
The rotational displacement is the torque applied to the input shaft 1, ie, the steering torque.
Is proportional to Accordingly, the movable iron core 16 is connected to the pin 11b.
Convert to axial displacement Z. That is, the steering torque is
The axial displacement of the core 16 is proportional to the axial displacement
It is detected by the unit 17. As described above, the torque detector 3 is provided with the pinion
1b, rack shaft 4, pinion holder 12, pin 11
b, a movable portion 16 and a differential transformer.
And its direction are detected. A number of slits 18a are formed around the input shaft 1.
A light-shielding plate 18 having a direction is provided integrally.
Photocouplers 19 and 20 are located at positions sandwiching the light shielding plate 18 of FIG.
It is integrally fixed to the pinion holder. Light is blocked by the photocouplers 19 and 20.
The light passing through the slit 18a of the plate 18 is detected and pulsed.
An electric signal is output. Also, the photo coupler 19
And 20 are different in the pulse phase by about 90 °
Provided. Thus, the steering speed detecting unit 2 is shielded from light.
A plate 18 and photocouplers 19 and 20
The magnitude of the steering speed and the rotation speed are detected. The outer periphery of the end of the rack shaft 4 has a male having a semicircular cross section.
A screw 4a is formed, and around this male screw 4a,
A nut 21 having a female screw having a semicircular cross section is mounted around the
Between the male screw 4a and the female screw.
The male screw 4a, the nut 21 and the bolt
The ball screw 5 is constituted by a screw. A rack casing is provided at one end of the nut 21.
A thrust bearing 22 fixed to the nut 2
A pulley 23 having a V-shaped section is integrally provided at the other end of the pulley 1.
ing. Further, a rack case is provided on the end face of the pulley 23.
A fixed thrust bearing (not shown) is provided.
The nut 21 is axially immovable and rotatably supported.
I have. The rotation of the motor 7 along the pulley 23
A pulley 24 having a V-shaped cross section attached to the shaft is provided.
And a V-belt 25 between these pulleys 23 and 24.
Have been suspended. The electric motor 7 is attached to the vehicle body via an elastic member.
Supported. Therefore, the rotation of the motor 7 is
The rack shaft 4 is displaced in the axial direction through the rotation of the
The Rukoto. On the other hand, the control means is a power supply circuit 9A,
From the computer unit 8 and the motor drive circuit 9
Become. Photo couplers 19 and 20 have microcomputers.
Power is supplied through the data unit 8 and the photo
Output from the microcomputers 19 and 20
Is input to the port 8. Also, the coil portion 17 of the differential transformer
The microcomputer unit 8 is connected to the primary winding 17a.
Pulse-like voltage is supplied from the secondary coils 17b and 17
The output from c is input to the microcomputer unit 8
Have been. The power supply circuit 9A is connected to the positive terminal of the vehicle battery 26.
A relay circuit 28 connected to the
The relay circuit 28 is provided with a microcomputer.
Control signal T from the data unit 8₁ On / off system by
And a motor drive described later from the output side of the relay circuit 8.
Power is supplied to the circuit 9. The motor drive circuit 9 is provided with a field effect transformer.
Transistors 30A, 30B, 31A and 31B.
Equipped with a bridge circuit. Bridge circuit of each other
A field effect transistor 30A located on the opposite side
30B, field effect transistors 31A and 31B respectively
Work together. The field effect transistors 30A and 31A
The drain terminal is connected, and this connection portion is connected to the relay circuit 28.
Of the field-effect transistor 30
B and the source terminal of 31B are connected.
It is connected to the common side (earth) via anti-32,
These connection parts become input terminals. Note that these field effect transistors 30
A, 30B, 31A and 31B are n-channel type
An enhancement type is used. This is, for example,
When using the channel enhancement type,
N-channel type with large on-resistance between source and source
This is because it is about twice as much as the comparison, and the voltage
This is because the loss is large. In addition, the electric field effect of the bridge circuit
Connection between transistors 30A and 31B, and electric field effect
The connection between the transistors 31A and 30B is the output side.
Connected to the armature winding of the electric motor 7. Further, the gate of the field effect transistor 30A is
The emitter terminal is connected to the ground terminal via a resistor 33.
Connected to the collector of the
Control signal T from the computer unit 8_Four Is entered
It is. Gate terminal of the other field effect transistor 31A
Similarly, a transistor with a common emitter via a resistor 35
Connected to the collector of the
Control signal T from computer unit 8_Five Is entered
You. The transistors 34 and 36
A relay circuit is connected to the collector via a resistor 37 or 38.
28 is connected to a booster circuit 39 connected to the output side of
The power supply for operation boosted by about twice by the booster circuit 39 of FIG.
Pressure is being supplied. this is,Field effect tiger on the high potential side
Between the drain and source when the transistor is turned on.
To keep the voltage to a minimum (eg, 1.0V or less)
is there. Therefore, the microcomputer unit 8
Control signal T_Four Or T_FiveAs a result, the transistor 34
Or 36 operates, and accordingly, each electric field effect
The transistor 30A or 31A is turned on / off.
You. The gate of the field effect transistor 30B is
The microcomputer terminal is connected to the
PWM drive control signal T from unit 8_Two Is entered
On the other hand, a resistor is connected to the gate terminal of the field effect transistor 31B.
41 from the microcomputer unit 8 via
WM drive control signal T_Three Is input and the PWM drive control signal
T_Two Or T_Three Field effect transistor 30B or
31B is PWM driven. Therefore, for example, the control signal T_Four To "L
Level ", PWM control signal T_Two Is a “PWM signal”,
In this case, another control signal T_Five To “H level”, T_Three To "L
Level ”or the control signal T_Five To "L level
”, PWM control signal T_Three Is a “PWM signal”.
If other control signal T_Four To “H level”, T_Two To "L level
To control the rotation direction of the motor 7.
Together with the PWM control signal T_Four Or T_Five Pulse width system
Thus, an appropriate control power is supplied to the electric motor 7. Thus,Of the present inventionClaim 1Automatic
For carsElectric power steering deviceThen, the motor drive
The path is a block using an n-channel field effect transistor.
A ridge circuit is provided, and voltage is applied between the input terminals of this bridge circuit.
Source, and the motor 7 is connected between the output terminals.
When generating auxiliary torque in one rotation direction from
A set of n that are opposite sides of the bridge circuit
Channel type field effect Of the transistors, the high voltage of the power supply
-Channel type field effect transistor connected to the ground side
Is turned on via the booster circuit 39 and the power supply
N-channel field-effect transistor connected to low potential side
Drive with a PWM signal outside the audible frequency range.
When generating auxiliary torque in the other rotation direction from machine 7
Are the other opposite sides of the bridge circuit.
Of a set of n-channel field effect transistors,
N-channel field effect transformer connected to the high potential side of the source
When the transistor is turned on via the booster circuit 39,
-Channel field effect connected to the low potential side of the power supply
Transistor driven by PWM signal outside audio frequency range
It is a configuration to make it.For the motor drive circuit,n-channel typeElectric
Power supply with bridge circuit using field effect transistor
High potential side ofN-channel type connected toField effect transformer
The transistor is turned on via the booster circuit.AndPower supply low potential
~ sideN-channel type connected toField effect transistorBut
Driven by PWM signal outside audio frequency rangeIsYou. Accordingly
2KH of the conventional electric power steering device
Whether the resonance sound and the parasitic vibration sound based on z are the body and the steering wheel
And the noise that the engine has
Discomfort caused by frequencies one digit higher than the noise frequency of the sound source
No more hitting the driver and the steering feel
The smoothness of the ring is not hindered. [0040]Of the present inventionClaim 2For carsElectric power
The water steering device is an n-channel enhancement
Field-effect transistor is used,
Field effect for large current due to low on-resistance of transistor
Battery voltage by reducing power loss in the transistor
Can be used effectively for driving a motor,
Output to increase transistor switching speed
Must be driven by a low impedance drive circuit
Is the transconductance of the field effect transistor (g
m) is high, and the drive circuit is downsized because of the voltage drive.
be able to. [0041]Of the present inventionClaim 3For carsElectric power
The water steering device is a bridge circuit field effect truck.
N-channel enhancement type field effect transistor
Of the field effect transistor 30A
A grounded emitter transformer is connected to the gate terminal via a resistor 33.
Is connected to the collector of the
Signal T from the microcomputer unit 8_Four Is entered
The same applies to the gate terminal of the field effect transistor 31A.
Of a transistor 36 with a common emitter via a resistor 35
Connected to the collector, the base of which
Signal T from the data unit 8_Five Are entered and
The collectors of transistors 34 and 36 have resistors 37 and
Or via 38 to the output side of the relay circuit 28
The boosting circuit 39 is connected to the
An operation power supply voltage doubled is supplied. Therefore, the microcomputer unit
Signal T from_Four Or T_Five By the transistor 3
4 or 36 operates, and accordingly, the respective electric field effect
The result transistor 30A or 31A is driven. Gate terminal of field effect transistor 30B
To the microcomputer unit 8 via the resistor 40
Signal T from_Two Is input while the field effect transistor is
A microcontroller is connected to the gate terminal of the
Signal T from the computer unit 8_Three Is input and the signal
T_Two Or T_Three Field effect transistor 30B or
Is driven by 31B. Therefore, for example, the signal T_Four And T_Two To
"PWM signal", and in this case other signals T_Five To “H level
Le ", T_Three To the “L level” or the signal T_Five When
T_Three Is a “PWM signal”, and in this case, other signals T_Four To
“H level”, T_Two To “L level”,
Controls the direction of rotation of motor 7 and is suitable for motor 7
Control power is supplied. Thus,Automatic according to claim 3 of the present invention
In electric power steering devices for vehicles, the motor drive
The path is a block using an n-channel field effect transistor.
A ridge circuit is provided, and voltage is applied between the input terminals of this bridge circuit.
Source, and apply power between the output terminals. Connect the motive 7 and the motor 7
When generating auxiliary torque in one rotation direction from
A set of n that are opposite sides of the bridge circuit
High potential of power supply among channel field effect transistors
N-channel field-effect transistor connected to the
Driven through a booster circuit 39, and the set of n channels
At least one of the field-effect transistors
Audio frequency range for n-channel field effect transistor
It is driven by an external PWM signal, and the other
When the auxiliary torque is generated in the
Another set of n-channel types that are opposite sides of each other
Connected to the high potential side of the power supply among the field effect transistors
The boosted circuit 39
And the other set of n-channel type
N-channel of at least one of the field-effect transistors
PW outside the audible frequency range
This is a configuration driven by the M signal.For the motor drive circuit,n
Channel typeBridge times using field-effect transistors
And a pair of opposing sides of the bridge circuit.
setOr another set of n-channel typeField effect transistor
At least one ofn-channel typeField effect tiger
Transistor is driven by PWM signal outside audio frequency range
So, in the electric power steering device including the electric motor
Resonant sound or parasitic in audio frequency range by PWM drive
Preventing the generation of vibration noise and the actual effects on the motor
The voltage of the electric power steering can be increased
The ability to reduce the steering force of the device can be enhanced. Also,
Handle return like a conventional electric power steering device
During operation, the direction of action of the rotating torque of the motor and the motor
The rotation directions of the robots do not match each other and hinder smooth operation.
And smooth steering wheel operation
And return operation. Next, another embodiment of the present invention is shown in FIG.
You. In FIG. 3, the motor drive circuit 9 has a small current capacity.
A bridge circuit is constructed by connecting field-effect transistors in parallel.
It has been achieved. That is to say, each of the
Of the field effect transistors 30A, 30B, 31A, 31B
Similar field effect on source and drain terminals respectively
Transistors 42A, 42B, 43A, 43B are connected in parallel
It is connected. Therefore, each field-effect transistor connected in parallel
Transistors 30A and 42A, 30B and 42B, 31A
43A, 31B and ON resistance between the source and drain of 43B
Resistance is even smaller, further reducing power loss
Becomes possible. As described above, in this embodiment, the electric field effect
By connecting transistors in parallel, small and low cost
It is possible to use a field effect transistor with a small capacity
Function and the current capacity can be increased.
It is possible to reduce the size and cost of the dynamic circuit. The above embodiment is an example of the present invention.
However, the present invention is not limited to the above embodiment.
No. [0050] According to the present invention, the following effects are exhibited by the above configuration.
I do. The electric power steering device according to claim 1 is
For the motor drive circuit,n-channel typeField effect transistors
A bridge circuit using a
Connect the power supply between the input terminals and the motor between the output terminals
And a pair of opposing sides of the bridge circuitOr
Another set of n-channel typeField effect transistor
The high potential side of the power supplyN-channel type connected toElectric field effect
Transistor is turned on via the booster circuit.ReToto
Low power side of power supplyN-channel type connected toElectric field effect
Transistor driven by PWM signal outside audio frequency range
The motor drive circuit can be downsized,
PWM drive in electric power steering system including motive
Of resonance or parasitic vibration noise within the audible frequency range
Because it can prevent the occurrence, improve the marketability,
Electric power steering system with good steering feeling
Can be provided. An electric power steering apparatus according to claim 2
The device is an n-channel enhancement type field effect transistor.
Low on-resistance of field effect transistors
Power in field-effect transistors for large currents
Efficient use of battery voltage for motor drive by reducing losses
And can be used to switch
Drives with low output impedance to increase
Need to be driven by a dynamic circuit,
Has high mutual conductance (gm) and current capacity
Field effect transistors in parallel to increase
However, the drive circuit can be downsized because of the voltage drive.
As a result, a practically sufficient steering assist
Lux, high steering power reduction ability, and power saving effect
Providing a highly efficient electric power steering device
it can. The electric power steering apparatus according to claim 3
Is installed in the motor drive circuit,n-channel typeField effect tiger
A bridge circuit using transistors.
Connect the power supply between the input terminals of the road and the motor between the output terminals.
Connect to the high potential side of the power supplyN-channel type connected toElectric
The field effect transistor is driven via the booster circuit,
Pair of opposing sides of the edge circuitOr another set
N-channel typeOf the field-effect transistors,
One ofn-channel typeAudible field effect transistor
Driven by PWM signal outside frequency range, including motor
Audible by PWM drive in electric power steering device
Prevent the generation of resonance or parasitic vibration noise within the frequency range
Drive efficiency and drive size.
Good and smooth steering wheel
Back and forth for smooth steering feel and
An electric motor with high power saving effect and high steering power reduction ability
A water steering device can be provided. According to the present invention, the high potential side of the bridge circuit isBoth n
Channel typeField effect transistorButThrough the boost circuit
DriveIsConfiguration, the high-potential sideBoth sidesField effect
The transistor can be sufficiently turned on, and the motor
FromAbout both rotation directionsGenerate sufficient auxiliary torque
be able to. Therefore,Left and rightSmooth steering wheel
With high power saving effect and further reduced steering force
Providing high-performance electric power steering devices
Can be.

Overall configuration diagram of an electric power steering apparatus according to BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] The present invention Figure 2 rack shaft and in FIG. 1 showing the pinion II-II
FIG. 3 is a sectional view taken in the direction of an arrow. FIG. 3 is a diagram of a motor drive circuit of the electric power steering apparatus according to the present invention.
1A, 31B, 42A, 42B, 43A, 43B ... n
Channel type field effect transistor.

Claims (1)

(57) [Claims] An electric power steering apparatus comprising: a motor drive circuit for performing PWM drive on an electric motor that generates an auxiliary torque corresponding to a steering torque; wherein the motor drive circuit includes a bridge circuit using an n-channel type field effect transistor; A power supply is connected between the input terminals of the motor, the motor is connected between the output terminals, and an auxiliary torque is generated from the motor in one rotational direction.
In this case, of the pair of n-channel field effect transistors on the opposite sides of the bridge circuit,
An n-channel field-effect transistor connected to the high potential side of the power supply is turned on via a booster circuit, and the n-channel field-effect transistor connected to the low potential side of the power supply is set to an audio frequency. It is driven outside the scope of the PWM signal to generate an auxiliary torque from the electric motor in the other rotational direction
The opposite sides of the bridge circuit
Another set of n-channel field effect transistors
That is, an n-channel type power supply connected to the high potential side of the power supply.
Drive field effect transistor on via booster circuit
And an n-channel connected to the low potential side of the power supply
-Type field effect transistor with PWM signal out of audio frequency range
An electric power steering device for an automobile, which is driven by a motor. 2. 2. The electric power steering apparatus for an automobile according to claim 1, wherein an n-channel enhancement type field effect transistor is used as the n-channel type field effect transistor. 3. An electric power steering apparatus comprising: a motor drive circuit for performing PWM drive on an electric motor that generates an auxiliary torque corresponding to a steering torque; wherein the motor drive circuit includes a bridge circuit using an n-channel type field effect transistor; A power supply is connected between the input terminals of the motor, the motor is connected between the output terminals, and an auxiliary torque is generated from the motor in one rotational direction.
If you are, before one of a set of n-channel type field effect transistor together the opposing opposite side of the bridge circuit
N-channel type field effect connected to the high potential side of the power supply
Driving the transistor through a booster circuit;
Less of the set of n-channel type field effect transistor <br/> and also to drive the one of n-channel type field effect transistor at audio frequencies outside the range of the PWM signal to generate an auxiliary torque from the electric motor in the other rotational direction
The opposite sides of the bridge circuit
Another set of n-channel field effect transistors
An n-channel electric field connected to the high potential side of the power supply
Drive the effect transistor through the booster circuit and
Another set of n-channel field effect transistors
At least one n-channel field effect transistor
An electric power steering device for an automobile, wherein the motor is driven by a PWM signal outside an audible frequency range .