JPH01103572A - Electric power steering device - Google Patents

Abstract

PURPOSE:To aim at reduction in any effect of load to other electrical equipment by installing two types of voltage takeoff ports in an engine-driven generator, feeding power to a PS voltage motor from a generator takeoff port during engine driving, and performing the feed from a car-mounted battery at engine stoppage. CONSTITUTION:A steering angle or the like of a handwheel shaft 2 is detected by a torque detector 10 and inputted into a PS control circuit 11, thereby operating a chopper controller 20, and a PS operating electric motor 7 is driven. A generator 17 being free of being driven by an engine 13 is installed there, and two types of voltage takeoff ports A, B are installed in the generator 17. At the time of engine driving, the PS electric motor 7 is fed out of the takeoff port B, and the takeoff port A is used for charging of a battery 18 for car-mounted equipment use. At the time of nondriving of the engine, all feed inclusive of the PS electric motor 7 is carried out by the battery 18. Unloading of a car-mounted battery is promoted, whereby any effect due to load to other electrical equipment is thus reducible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a power steering device for an automobile that relies on DC power as an energy source for generating auxiliary steering force, and particularly relates to a power steering device for an automobile that relies on DC power as an energy source for generating auxiliary steering force. The present invention relates to an electric power steering device suitable for passenger cars that uses a DC motor as an actuator.

[Conventional technology]

In recent years, so-called electric power steering devices, which use electric motors as actuators to generate auxiliary steering force, have attracted attention because of their ease of installation in the engine compartment and the ease with which they can be controlled. However, as described in Japanese Unexamined Patent Application Publication No. 59-156863, conventional devices directly use the DC power obtained from the vehicle battery as a power source for the electric motor for generating auxiliary steering force. Or, JP-A-61-9191
As described in the above publication, there was one in which a step-up chopper was used to obtain AC power with a voltage higher than the voltage of the onboard battery, and this used to drive an AC motor to obtain auxiliary steering force.

[Problem that the invention seeks to solve]

Among the above conventional technologies, the former does not take into consideration the large current consumption by the electric motor for generating auxiliary steering force during power steering operation, and is particularly effective when the power steering is performed at night or when steering while driving. There was a problem in that the lights dimmed, negatively impacting the operation of various electrical devices installed in the car, such as lights, wipers, and air conditioners.

On the other hand, the latter method does not take into consideration the need for an extra boost chopper, resulting in increased costs and extra space, and furthermore, the switching elements used in this boost chopper and smoothing There was a problem with extra maintenance on the capacitors.

An object of the present invention is to provide an electric power steering device that is low cost and can function satisfactorily without adversely affecting other on-vehicle devices that share the on-vehicle battery.

Means for Solving Problem C] The above purpose is to generate different voltages from an engine-driven generator installed to supply power to electrical on-board equipment and charge the on-board battery. When the engine is running, one of these electric powers is used for power steering and the other is used for charging the vehicle battery.When the engine is stopped, the power for power steering is also connected to the vehicle. This is achieved by taking it from the battery.

[Effect]

Since power is supplied from different power systems to the power steering system and other in-vehicle equipment systems, even if the power steering operates, there is almost no effect on other in-vehicle equipment, and the power steering system Since the power supply voltage can be increased independently of other on-vehicle equipment, the power steering system operates reliably.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric power steering device according to the present invention will be described in detail below with reference to illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a rack-and-pinion type steering system. In the figure, 1 is a steering wheel, 2 is a steering shaft, 3 is an intermediate shaft, 4 is a pinion, and 5 is a steering wheel. is a rack shaft, 6 is a steering gear box, 7 is a high-voltage DC motor that serves as an actuator for generating auxiliary steering force, 8 is a speed reducer, 9 is a pinion for auxiliary steering force, 10 is a torque detector, 11 is a Control circuit, 12 is on-vehicle equipment (load) such as lamps, 13 is engine, 14° and 16 are pulleys,
15 is a belt, 17 is a generator for charging, 18 is a battery, 20 is a chopper control device, and 21 is a diode.

The steering wheel 1 is rotated by the driver, and this rotation causes the rack shaft 5, which is slidably held within the steering gear box 6, to slide in its axial direction via the intermediate shaft 3 and pinion 4. When steering is performed, a torque appears on the steering shaft 2, which torque is detected by the torque detector 10 and a corresponding signal is generated. Then, this signal and a signal from a steering angle sensor (not shown) are input to the control circuit 11, and in response to this, the control circuit 11 inputs a control signal to the chopper control device 20, and the electric power is supplied to the motor 7. is controlled to generate a predetermined torque, and this torque is applied to the rack shaft 5 via the reducer 8 and pinion 9, thereby generating auxiliary steering force and operating as power steering.

The motor 7 has a high voltage specification, for example, 48V, which is higher than the terminal voltage of the battery 18, and accordingly, the generator 17 has first and second DC outputs, as will be described later. The DC output is connected to the battery 18 to charge the battery 18, and the other DC output is a higher voltage output than the battery 18, such as 48V, and is used for chopper control. It is supplied to the motor 7 via the device 20.

Further, the generator 17 is driven by the engine 13 via the belt 15 and pulleys 14 and 16.

FIG. 2 shows an embodiment of the generator 17, and as mentioned above, this generator 17 can charge the 12V battery 18,
Similarly, a relatively low voltage first DC output A is used to supply power to various loads 12 (12), and a relatively high voltage (12) is used to drive the motor 7 of the power steering system.
48V), and for this reason, the two sets of armature windings 112, 113,
It is also equipped with two sets of rectifiers (diodes) 115 and 117, but other than that, it is a general automotive generator (AC
A pulley 16 is attached to a shaft 101 supported by two bearings 117, and a rundle-shaped iron core 102 and a field winding 103 are connected to the shaft 101. A rotor is formed.

The field winding 103 includes a slip ring 104 and a brush 105.
A predetermined excitation current is supplied to the armature windings 112 and 113 by a voltage regulator (not shown). A three-phase AC voltage is generated, and these are connected to rectifiers 115 and 11 through lead wires 114 and 116.
7 and their respective terminals A1. A2, B+, B
z to generate first and second DC outputs.

In addition, in this FIG. 2, 106 is a brush holder, 109.
110 is a bracket, and 111 is an armature core.

Next, the operation of this embodiment will be explained with reference to FIGS. 3 to 5.

First, FIG. 3 shows the overall connection state. The chopper control device 20 is represented by a switching transistor, which is connected in series with the motor 7, and the armature winding 112 of the generator 17 (see FIG. 2). ) is directly connected to the second DC output B (high voltage side) obtained from the output of the rectifier 115 via a lead wire 114. Note that 22 is a flywheel diode.

On the other hand, the first DC output A (low voltage side) obtained from the armature winding 113 (FIG. 2) of the generator 17 to the output of the rectifier 117 via the lead wire 116 is connected to the battery 8 and the load I2.
are connected in parallel to each other, supplying power to these, and also connected in parallel to the second DC output B via a reverse current blocking diode 21.

Although a control circuit for switching the rotation direction of the motor 7 between forward and reverse is actually included, it is omitted in this embodiment.

As is clear from FIG. 3, the diode 21 is provided in this embodiment, and as a result, the generator 17 is driven to rotate and generates a predetermined amount of power, and when it is not. It operates so that the power supply source for driving the motor 7 that generates the auxiliary steering force for power steering is automatically switched, and this point will be explained below with reference to FIGS. 4 and 5. do.

First, referring to FIG. 4, we will explain the operation when the engine 13 is rotating and electric power of a predetermined voltage can be obtained from the generator 17.
Since the voltage V of the second DC output B of the motor 7 is 48V, and the voltage vA of the first DC output A (7) is 12V, the diode 21 is reverse biased and remains in the off state. Electric power is supplied only from the second DC output B, and the chopper control device 20 is operated by the control signal from the control circuit 11, and a predetermined current 1 is supplied to the motor 7, thereby producing a predetermined auxiliary steering force. is given, and the function as power steering is obtained.

At this time, since the voltage specification of the motor 7 is 48V, the current (1) for generating the necessary auxiliary steering force is 12V when operating at 12V as in the conventional example. It can be reduced to 1/4 compared to the previous year.

Next, the operation when the engine 13 is stopped will be explained with reference to FIG. 5. Since the generator 17 is not driven at this time, both the first and second outputs are zero. Therefore, the voltage VA is maintained at approximately 12V due to the presence of the battery 18.

Therefore, this time, the diode 21 becomes a forward bias state, and when the chopper control device 20 is operated by the control circuit 11, electric power 2 is supplied from the battery 18 to the motor 7, and the motor 7 generates torque 7. Then, auxiliary steering force is applied and the power steering function is activated.

At this time, the voltage specification of the motor 7 is 48V, and since it is operated with a voltage of 12V from the battery 18,
Although the response speed will be slower, the magnitude of the current ■2 depends on the control state of the chopper control device 20, so the current ■2 in the case of FIG.
Since the value can be maintained at the same value as 1, the same value can be obtained as the auxiliary steering force.

Furthermore, at this time, as is well known, the backflow of current to the generator 17 side is blocked by the rectifiers 115 and 117, so no problem occurs.

By the way, in the above embodiment, the output voltage of the power generation a17 is
Although 12V was selected for the first DC output A and 48V was selected for the second DC output B, these voltage ratios can be arbitrarily selected. For example, if the ratio of these voltages is selected to be greater than 4:l, the current can be further reduced, so that the capacitance of the chopper transistor and the thickness of the wiring can be further reduced.

Further, in the above embodiment, a transistor is used as the chopper element, but a switching element such as a gate turn-off transistor, a silice, a field effect transistor (FET), etc. may also be used.

Furthermore, in the above embodiment, the DC motor 7 is used as the actuator for generating auxiliary steering force, but this motor is not limited to a DC motor, but may be an AC motor such as an induction motor, or a brushless type (DC motor). Various types of motors are used, including those with synchronous machines. Of course,
Needless to say, the method can be implemented using a DC motor regardless of its field type.

FIG. 6 shows an embodiment in which a brushless DC motor is applied to the present invention as an actuator for generating auxiliary steering force. Parts with the same reference numerals as those in FIG. 3 will not be described.

The difference between the embodiment shown in FIG. 6 and the embodiment shown in FIG. 3 is that the second DC output B, that is, the output on the high voltage side,
0 is connected to a synchronous machine type brushless DC motor 7', and a reverse blocking diode 21, a common connection on one side of the high voltage side and the low voltage side is provided between the impark 50 and the rectifier 115. be.

With this configuration, this embodiment eliminates the need for a step-up chopper, and allows the brushless DC motor to be operated at high voltage while the engine is rotating and on battery power when the engine is stopped. In addition, in FIG. 6, the motor 7' may be an induction motor.

By the way, in the above embodiment, only the electric power steering motor is connected as the high voltage side load.
It is not particularly limited. For example, by connecting the ignition system to the high voltage side, it is possible to eliminate the disadvantage that the ignition timing becomes short at high speeds and the power supply does not start up. Furthermore, if all general motors such as motors for Kartara are connected to the high voltage side, the motor current can be reduced.

Further, although the embodiment shown in FIG. 1 is explained using electric power steering, the present invention may be applied to an electro-hydraulic type power steering device.

〔Effect of the invention〕

According to the present invention, the electric power steering chopper transistor and motor can be operated at high voltage while the engine is rotating, so the current can be reduced to the reciprocal of the ratio of high voltage to low voltage. . Therefore, it is possible to reduce the capacitance of the chopper transistor and the thickness of the wiring, resulting in an inexpensive drive system.

In addition to the high voltage mentioned above, the low voltage side charges the battery and also supplies power to general loads and control devices, so even if you operate the power steering motor during night driving, the light intensity of the lights will be dim. It will never happen.

Furthermore, since the power on the high voltage side is directly obtained from the armature winding provided in the charging generator via the rectifier, there is no need to provide a step-up chopper, resulting in a long-life and compact system. In addition, even when the engine is stopped, the electric power steering motor can be operated by the battery at a low current, so the power steering can be operated even when the vehicle is being transported by a truck in the event of an engine failure.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram showing an embodiment of an electric power steering device according to the present invention, FIG. 2 is a partial sectional view showing an example of a generator in an embodiment of the present invention, and FIG. 3 is a system configuration diagram showing an example of a generator in an embodiment of the present invention. FIGS. 4 and 5 are circuit diagrams for explaining the operation, and FIG. 6 is a circuit diagram showing another embodiment of the present invention. 1... Steering wheel, 2...
Steering shaft, 3... intermediate shaft,
4... Binion, 5... Rack shaft, 6
...Steering gear box, 7...
・Motor, 8...Reducer, 9...Binion, 10...Torque detector, 11...
・Control circuit, 12...In-vehicle equipment (negative r@), 1
3... Engine, 14.16... Pulley, 15... Belt, 17... Generator for charging, 18... Battery , 20...
- Chopper control device, 21... Diode for backflow prevention. Figure 1 1: Ste? Link ゛Small connection 1o: Torque sheep history power output Fig. 2 Fig. 3 Fig. 4 Fig. 6 Fig. 5゜

Claims (1)

[Scope of Claims] 1. In a power steering system for an automobile in which the energy source of the actuator means for generating auxiliary steering force is dependent on an on-vehicle DC power source, a first DC power supply having a predetermined voltage for charging an on-board battery is provided. an engine-driven generator generating a power output and a second DC power output having a voltage higher than the voltage of the first DC power output; An electric power steering device characterized in that it is configured to depend on DC power output and on the vehicle-mounted battery when the engine is stopped. 2. In claim 1, the generator is an alternating current generator equipped with first and second independent armature windings, and The incoming first and second AC voltages are rectified and the first and second AC voltages are rectified.
An electric power steering device characterized in that it is configured to obtain a DC power output of . 3. In claim 1, it is provided that the first DC power output is connected in parallel to the vehicle battery and further connected in parallel to the second DC power output via a reverse current blocking diode. A distinctive electric power steering device.