JPH0753508B2 - Electric power steering control system - Google Patents

Description

The present invention relates to an electric power steering control system,
In particular, the present invention relates to an electric power steering control system suitable for applying an auxiliary steering force by a motor drive to a steering system of an automobile.

[Conventional technology]

Conventionally, an electric power steering control device is disclosed in Japanese Patent Laid-Open No. 61-12.
As described in Japanese Patent Publication No. 5964, a second generator is provided in addition to the charging system generator, and the generated pressure proportional to the engine speed generated by the generator is generated according to the output of the steering torque sensor. It was being supplied to the electric motor for power steering.

[Problems to be solved by the invention]

The above prior art does not consider driving the electric power steering device at a high voltage, and the control system cannot be downsized. The power steering device is effective only when the engine is driven, and the power assist when the engine is stopped is not provided. Since this is not taken into consideration, assisting force cannot be obtained when the vehicle stalls in the muddy state, and it is difficult to escape in an emergency.

That is, since the output voltage of the second generator of the above-mentioned known technique changes in proportion to the engine speed, the current range in the controller of the control circuit becomes wider. Therefore, the current pulsation is large and the system efficiency is low. Therefore, a sufficient assist force cannot be obtained when idling. Further, since the power steering control generator is also driven by the engine, there is a drawback that the assist force required when the engine is stopped cannot be obtained.

A main object of the present invention is to provide a control system that can reduce the electric current of an electric power steering control device, be compact, and improve reliability.

Another object of the present invention is to provide a control system capable of operating an electric power steering device at a high voltage regardless of whether the engine is rotating or stopped.

[Means for solving problems]

The above object is achieved by applying a voltage higher than the vehicle battery voltage to the input terminal of the electric power steering control device and allowing the battery to be charged through a control circuit having a step-down and step-up function.

If the output voltage of the charging generator is the same as the battery voltage, this can be achieved by boosting the output voltage and inputting it to the control device.

[Action]

When the engine speed is idling speed or higher and the output of the charging generator is high voltage, the battery voltage is supplied to the drive power steering device at a higher voltage than the conventional one via the booster in other cases. , The supply current decreases as the voltage increases. In addition, the conventional 12V battery is used for normal loads, and this battery is charged through the step-down capacitor when the output of the charging generator is high voltage, and directly when it is low voltage. To charge. For this reason, even if the electric power steering device operates, there is no direct influence such as a drop in battery voltage, so that the brightness fluctuation of the lamp load due to the voltage fluctuation is also eliminated.

On the other hand, when the engine is stopped, electric power is not supplied from the charging generator to the electric power steering device, but since electric power is supplied from the battery via the booster circuit, the electric power steering device is operated with a small current as when the engine is rotating. Can be made.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the basic system configuration of the electric power steering system of the present invention. 1 is a steering wheel (hereinafter, simply referred to as a steering wheel), 2 is a handle shaft, 3 is a torque sensor, 4
Is a pinion, 5 is a rack, 6 is a turning tire (wheel), 7 is a motor for power assist, 8 is a speed reducer, 9
Is a pinion, 10 is a steering angle sensor, 11 is a control device for electric power steering (hereinafter, simply referred to as a control device), 12 is a step-down chip circuit for charging battery 13, and power is supplied from battery 13 to electric power steering when the engine is stopped. In order to do so, the boost / step-down checker circuit having a boosting function also detects whether the engine 14 is stopped or is rotating by the engine rotation determination circuit 25 and operates either the boost or step-down checker. A charging generator 15 is directly connected to the engine 14 via a belt or the like, and the charging generator 15 is rotated to generate a set voltage, and its output is set to direct current via a full-wave rectifier 16. It is configured to output the generated voltage.

In this embodiment, the so-called rack and pinion system is used, and the steering force applied to the steering wheel 1 by the driver is applied from the steering wheel shaft 2 to the pinion 3 via the torque sensor 3 and the torque sensor 3 turns the steering wheel. The torque is detected and a signal τ representing the magnitude of the torque is obtained. The torque sensor 3 generates a strain gauge or twist, and the amount of twist is taken out from a variable resistor or the like. The electric motor 7 operates as an electric actuator which gives an auxiliary steering force to the rack 5 via a speed reducer 8 including a gear device and a pinion 9. The rudder angle sensor 10 detects the rudder angle of the tire 6, and outputs a signal with the rudder angle being zero when the vehicle is in a straight traveling state, that is, when the rudder angle of the tire 6 is in the neutral position.

For example, a linear encoder or the like is attached to the rack or the like. Electric motor 7 used in this power steering device
DC motors, brushless DC motors, and induction motors are applied. The control device 11 that controls the torque and the rotation speed of the electric motor is configured to control the voltage applied to the electric motor or the current to the electric motor according to the vehicle speed vs, the torque τ, and the steering angle θ.

FIG. 2 is a schematic diagram of a main circuit configuration and a control circuit of the present invention. A charging system including an engine 14, a charging high-voltage generator 15 and a rectifying device 16 is connected to a forward and reverse rotation field via a capacitor 126. The DC winding 7a is driven by exciting the magnetic windings 72, 73, the battery 13 is charged from the charging system via the step-down chopper circuit transistor 121, and conversely, the engine 14 is charged.
The boost chopper is operated by switching the reactor 125 and the transistor 123 forming the boost chopper circuit so that the electric power steering apparatus operates even when the boost chopper is stopped.

First, the state where the engine is stopped when the key is inserted and the electric circuit is in the ON position (not shown) will be described. Whether the engine is stopped or not is detected by detecting the rotation speed N _e of the engine 14 and input to the engine rotation determination circuit 25, N _e
When = 0, the output is input to the voltage command circuit 28 forming the control circuit of the booster chip, and the voltage command V ₁ from the voltage command circuit 28 and the terminal voltage detection value −Vc of the smoothing capacitor 126 are input.
Are matched with _{each other to} generate a differential command signal ΔV ₁ (= V ₁ −Vc) and input to the base drive circuit 29 of the transistor 123. In the base drive circuit 29, until the ΔV ₁ = 0, the transistor is turned on and off by the circuit configured by the reactor 125, the transistor 123, and the flywheel diode 124 to boost the battery voltage,
V of the high voltage generator 15 for charging the capacitor 126 via 122
Charge until it reaches the same value as the output voltage, and always maintain the same value. When the bundle 1 is operated in this state, the torque detection signal τ from the torque detector 3 is input to the function generator 21, and depending on whether the detected torque τ is positive or negative, the base drive circuit
A drive signal is input to any one of 23 and 24, and either the forward rotation transistor 111 or the reverse rotation transistor 112 performs a checker operation, the DC motor 7a is driven, and a steering assist force is generated.

Further, even if the vehicle is stopped and the engine is stopped after traveling, if the position of the key is at a position where the electric circuit is turned on, the steering assist operation can be naturally performed by the steering wheel operation to obtain the steering assist force.

Next, the state after starting the engine will be described. In this case, the engine is rotating, so the engine rotation determination circuit
In 25, it is judged that N _e ≠ 0, and the voltage command circuit for the step-down chip
The voltage command circuit 26 outputs the voltage command V ₂ and the voltage command V 26 is compared with the detection voltage −V _b of the battery 13 to obtain ΔV ₂ (= V ₂
-V _b ) is obtained and input to the base drive circuit 27 for the transistor 121 for step-down chip. In the base drive circuit 27, the step-down chip transistor 121 is operated by the voltage command of ΔV ₂ to flow the charging current of the battery 13 and charge the battery 13. At the same time, when the handle 1 is operated at this time, the output of the torque detector 3 is input to the function generator 21 in the same manner as described above, and the V function generator 21 requires the required current command I ₀ according to the input torque signal. And also outputs positive and negative signals corresponding to the torque detection value, and inputs them to the signal processing circuit 22 having a sign discrimination function and a matching function between the current command I ₀ and the motor current detection signal I _1, and the positive and negative signals are input. Signal to drive one of the transistors 23 and 24 to operate the DC motor 7
Drive a to obtain steering assist force. The torque sensor 3
The torque sensor output and the motor current command detected in step 3 can be set by the function generator 21 using the continuous speed vs as a parameter as shown in FIG. 3, and the steering angle and return as shown in FIG. By preparing the function of torque, the required characteristics of the electric power steering can be obtained.

FIG. 5 shows a system in which the voltage of the charging generator is low. In FIG. 5, a low voltage generator for charging
The armature winding (not shown) of 15a is wound with a low voltage specification, and the output of AC is a low voltage set by DC through the rectifier 16. This low voltage output is directly
Is charged and electric power is supplied to the general load 100 and the control device 11. Further, the motor 7a is connected to the low-voltage output via a booster chip 60 including a reactor 125, a transistor 123, a feedback diode 124, a diode 127, and a smoothing capacitor 126. After the engine is started, the switching step-up chip 60 of the reactor 125 and the transistor 123 operates to step up the low voltage to the high voltage and supply the electric power to the motor 7a. Also, when the engine is stopped, there is no output from the charging generator 15a, but the voltage of the battery 13 is above the boost boost level.
Via 60, the high voltage is applied to the motor 7a in the same manner as when the engine is rotating, and by the signal from the control device 11,
Either the forward rotation or the reverse rotation transistor performs the tipper operation. Therefore, the electric motor 7a is driven to generate an assisting force as in FIG.

FIG. 6 shows a configuration of the electric motor 7 of FIG. 2 when a brushless DC machine or an induction machine 7b is used. The main circuit 110 of the control device for controlling the rotation speed and torque of the electric motor 7b is composed of a transistor inverter, The base drive circuit 30 is composed of a signal processing circuit having a sign discriminating function, a current command and a detected current matching function, and inputs a required base signal to a transistor forming an inverter to drive the electric motor 7 in a forward or reverse direction. , Get steering assist force of steering wheel. Further, in FIG. 5, it is obvious that the main circuit of the control device for controlling the rotation speed and torque of the electric motor 7a may be constituted by a transistor inverter, and the electric motor 7a may be a brushless DC machine or an induction machine. Further, in the present invention, the ratio of the high voltage supplied to the electric power steering motor to the battery voltage can be arbitrarily selected, and the current can be further reduced by increasing the ratio.

Further, although only the electric power steering device is connected to the high voltage side in the present invention, the invention is not particularly limited, and the ignition device, the atomizer, and the other on-vehicle electric motors are excluded from the high voltage except for the general load of the light. You may connect to the side.

As described above, according to the present invention, the armature winding of the charging generator is configured with one set of high voltage or low voltage specifications, and when the engine is rotating, the output from the charging generator is high. In the case of the voltage, the electric power is directly supplied to the electric power steering device via the booster capacitor in the case of the low voltage output. When the output of the charging generator is high voltage, the battery is lowered to a chargeable voltage via the step-down capacitor and charged when the output of the charging generator is high, and directly connected when the output is low voltage. Be charged. On the other hand, when the electric power steering is driven when the engine is stopped, the standard (12V) battery output is supplied to the electric power steering device as a high voltage via the booster capacitor. Even if the electric power steering is operated during traveling, the general load such as a light and a lamp is supplied with electric power from the battery, so that there is no voltage fluctuation and the light amount of the light does not become dark.

Also, when the engine is stopped and escapes from the muddy state or when stationary, while the vehicle is supplying power to the electric power steering device via the booster booster from the battery, the battery voltage will drop somewhat, but as a light load Even if it is dark, there is no inconvenience because it is stopped.

Further, since the input voltage of the electric power steering device is set high, the current becomes small, and the electric motor to be used, the reverse rotation switching element and the like can be small in capacity, which makes it compact and economical.

Of course, by suppressing the current to be small, the thickness of the wiring can be made thin and the resistance loss of the circuit can be made small, so that there is an advantage that the heat generation in the engine room can also be reduced.

〔The invention's effect〕

According to the present invention, a voltage higher than the on-vehicle battery voltage is applied to the input end of the electric power steering controller,
The battery can be charged via the control circuit having the step-down and step-up functions, and the electric power steering control device can have a low current, and a compact and highly reliable control system can be obtained.

[Brief description of drawings]

The drawings show an embodiment of an electric power steering control system according to the present invention. FIG. 1 is an overall schematic configuration diagram, FIG. 2 is a control circuit diagram in one embodiment, and FIG. 3 is a motor current with respect to an output of a torque sensor. FIG. 4 is a characteristic diagram relating to the restoring force of the steering angle and torque, FIG. 5 is a control circuit in another embodiment, and FIG. 6 is a control circuit diagram showing still another embodiment. 1 ... Handle, 3 ... Torque sensor, 4 ... Pinion, 5 ... Rack, 7 ... Electric motor, 8 ... Reduction gear, 11 ...
… Electric power steering controller, 12 …… Step-down / step-up chip circuit, 13 …… Battery, 15 …… High-voltage generator for charging.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuji Marumoto 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Toshiyuki Koterasawa 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Japan Co., Ltd. Hitachi Research Laboratory, Hitachi Research Institute (72) Mitsuyuki Inventor Headquarters 4026, Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Institute, Ltd. (72) Tadashi Takahashi 4026 Kuji Town, Hitachi City, Ibaraki Hitachi Research Institute, Ltd. (72) Inventor Shuichi Takamatsu 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Hitachi Ltd. (72) Inventor Hirohisa Yamamura 2520 Takaba, Katsuta City, Ibaraki Prefecture Hitachi, Ltd. Factory Sawa Plant (72) Inventor Toru Torusaki 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi, Ltd. (72) Inventor Riki Omae 4026 Kujicho, Hitachi City, Ibaraki Hitachi, Ltd. Hitachi Ltd. In-house (72) Inventor Toshiaki Okuyama 4026 Kuji-machi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory (56) References JP-A-63-242772 (JP, A) JP-A-55-94546 (JP, A) Japanese Patent Laid-Open No. 61-125964 (JP, A) Actually developed 62-129369 (JP, U)

Claims (7)

[Claims] 1. A motor for assisting the driving of a vehicle steering device through a speed reducer, a controller for controlling the output of the motor according to the magnitude of a detection value of a torque detector provided on a steering shaft, In an electric power steering control system including a battery that supplies driving power to a control device and a charging generator, the output voltage of the charging generator is set higher than the battery voltage, and the charging is performed while the engine is rotating. An electric power steering control system characterized in that an output voltage from a generator is raised and the battery voltage is raised when the engine is stopped to be supplied to the electric motor. 2. The electric motor power steering control system according to claim 1, wherein the booster circuit is controlled by an output signal of a detecting means for detecting engine stop. 3. A motor for assisting the drive of a vehicle steering device through a speed reducer, and a controller for controlling the output of the motor according to the magnitude of the detected value of a torque detector provided on the steering shaft. In an electric power steering control system including a battery that supplies driving power to the control device and a charging generator, the output voltage of the charging generator is set higher than the battery voltage, and the charging is performed during engine rotation. The output voltage of the generator is supplied to the electric motor through the control device and the battery through the step-down circuit, and the battery output voltage is supplied to the control device through the boost circuit while the engine is stopped. An electric motor power steering control system characterized by the above. 4. The electric power steering control system according to claim 3, wherein the step-down and step-up circuits are composed of a chopper circuit and are switched and controlled according to rotation and stop of the engine. 5. The method according to claim 3, wherein the step-down chopper is operated by obtaining a rotation signal while the engine is rotating.
The output power voltage of the charging generator is controlled by a step-down chopper so that the output power voltage becomes the charging voltage of the battery, and the output voltage of the charging generator of high voltage is applied to the electric power steering device. An electric motor power steering control system characterized by being used as a power source for an electric power steering device. 6. A motor for assisting the driving of a vehicle steering device through a speed reducer, and a controller for controlling the output of the motor according to the magnitude of a detection value of a torque detector provided on a steering shaft. In an electric power steering control system including a battery for supplying driving power to the control device and a charging generator, the output of the charging generator is used to charge the battery and the output of the charging generator is boosted. The electric power steering control system is characterized in that it is supplied to the input end of the control device. 7. The electric power steering control system according to claim 6, wherein the battery voltage is boosted and supplied to the control device when the engine is stopped.