JP3028715B2 - Electric car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle, and more particularly, to an electric vehicle provided with an electric power steering device.

[0002]

2. Description of the Related Art As one type of electric power steering apparatus, for example, as described in Japanese Utility Model Laid-Open Publication No. Sho 61-172866, a power supply battery, an auxiliary steering motor using the battery as a power supply, and steering of a vehicle. A control device for controlling the steering assist force by controlling the motor according to the state, wherein when the battery voltage is equal to or lower than a predetermined value, the supply of power from the battery to the motor is stopped to prevent overdischarge. A known power steering device is conventionally known. According to such a power steering device, when the battery voltage drops below a predetermined value, the supply of power from the battery to the motor is stopped, and the power steering device is switched to the manual steering device. It is possible to reliably prevent inappropriate assistance from being performed.

[0003] One of the electric vehicles equipped with an electric power steering device includes a generator for supplying electric power to a battery, and an auxiliary engine for driving the generator when the battery voltage falls below a reference value. An electric vehicle configured to be charged with electric power generated by a generator is also conventionally known. According to such an electric vehicle, the traveling distance can be made longer than that of an electric vehicle not provided with a generator and an auxiliary engine.

[0004]

However, if the electric power steering apparatus described in the above-mentioned publication is applied to an electric vehicle having a generator and an auxiliary engine as it is, the battery voltage is reduced when the auxiliary engine is started. Is temporarily reduced, an erroneous determination occurs in the detection of the battery voltage drop failure, and the power steering device may be unnecessarily switched to the manual steering device.

The present invention has been made in view of the above-described problems of the conventional electric vehicle as described above, and erroneously determines that the battery voltage has dropped even if the battery voltage temporarily drops when the auxiliary engine is started. It is an object of the present invention to provide an electric vehicle improved so that the power steering device is not unnecessarily switched to the manual steering device.

[0006]

According to the present invention, there is provided a power battery M as shown in FIG.
1, a generator M2 for supplying power to the battery, an auxiliary engine M3 for selectively driving the generator, and an electric power steering device M powered by the battery
And voltage detecting means M5 for detecting the voltage of the battery.
And an electric vehicle provided with power supply stopping means M6 for stopping the supply of power from the battery to the power steering device when the voltage of the battery falls below a predetermined value, and detecting the start of the engine. A start detecting means M7 for temporarily stopping the battery caused by the start of the engine when the start of the engine is detected ;
And a stop prohibition unit M8 for prohibiting the power supply stop by the power supply stop unit for a time equal to or longer than the time of the voltage drop .

[0007]

In accordance with the such a configuration described above, when the start-up of the auxiliary engine M3 is detected by the starting detection means M7, the auxiliary et
Temporary voltage drop of battery M1 due to engine start
Depending on the power supply stop by the power supply stop means by between stop prohibition means M8 of time or longer under is prohibited
Power steering device M4 from battery M1
Since the state in which power can be supplied to the battery M1 is secured, the engine is started to drive the generator M2 to supply power to the battery M1, thereby temporarily lowering the voltage of the battery to a predetermined value or less. However, the power supply stopping means M6 reliably prevents the power supply from the battery to the power steering device M4 from being stopped, so that the power steering device is unnecessarily switched to the manual steering device. Is prevented.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram showing one embodiment of an electric vehicle having an electric power steering device according to the present invention, and FIG. 3 is a block diagram showing an electronic control unit for auxiliary steering shown in FIG. FIG.

In FIG. 2, reference numeral 10 denotes a steering wheel. The steering wheel 10 drives a rack bar 16 via a steering shaft 12 and a steering gear box 14, and the left and right wheels not shown in FIG. The steering angle of the steered wheels is controlled. A power unit 20 is drivingly connected to the steering shaft 12 by a gear reduction mechanism 18. The power unit 20 includes an auxiliary steering motor 22 and an electromagnetic clutch 24 that selectively drives and connects the gear reduction mechanism 18 and the motor 22.
The auxiliary steering is performed by driving the steering shaft in the same direction as the rotation direction of the steering wheel.

In the illustrated embodiment, the steering shaft 12 has a torque sensor 26 for detecting a steering torque T.
Is provided, and the output of the torque sensor is supplied to the auxiliary steering electronic control device 28. The electronic control unit 28 has a vehicle speed V detected by the vehicle speed sensor 30.
Is also input. The operating power of the electronic control unit 28 is DC / DC from the auxiliary battery 32.
The driving power supplied to the motor 22 and the electromagnetic clutch 24 through the converter 34 is supplied from the auxiliary battery 32 by D
C / DC converter 34, junction box 3
6. It is supplied via drive circuits 38 and 40.

A traveling motor 44 is connected to the junction box 36 via an inverter 42, and drive power for the motor 44 is supplied from a main battery 46 via the junction box 36 and the inverter 42. The operations of the junction box 36 and the inverter 42 are controlled by a traveling electronic control unit 48, and the traveling motor 44 rotationally drives left and right driving wheels (not shown) via a transmission 50 and a differential unit 52. It has become.

Further, a generator 54 and an SOC meter 56 are connected to the junction box 36. The generator 54 is selectively driven by a power generation auxiliary engine 60 which is started by driving a starter motor 58 in response to a start command signal (starter signal) from the electronic control unit 48 for driving, and causes the junction box 36 to operate. Then, the main battery 46 is charged, and the auxiliary battery 32 is charged via the junction box 36 and the DC / DC converter 34. The SOC meter 56 detects the voltage Vm of the main battery 46 via the junction box 36 and
And auxiliary battery 3 via DC / DC converter 34
2 is detected, and the detection result of the SOC meter 56 is transmitted to the electronic control unit 28 for assisting steering and the electronic control unit 4 for traveling.
8 and is displayed on an indicator 62.

As shown in detail in FIG. 3, the electronic control unit 28 for auxiliary steering includes a central processing unit (CPU) 66.
Read-only memory (ROM) 68, random access memory (RAM) 70, input port device 72
And an output port device 74. These are microcomputers having a general configuration connected to each other by a bidirectional common bus 76.

The input port device 72 has a torque sensor 26
, A signal indicating the vehicle speed V detected by the vehicle speed sensor 30, a signal indicating the voltage Vs of the auxiliary battery 32 detected by the SOC meter 56, and a cell motor from the electronic control unit 48 for traveling. 58
A start command signal output to the controller is input. The input port device 72 appropriately processes the signal input thereto, and in accordance with the instruction of the CPU 66 based on the control program stored in the ROM 68, the CPU and the RAM 70.
And outputs the processed signal.

The ROM 68 stores a control program shown in FIG. 4 and maps corresponding to the graphs shown in FIGS. The CPU 66 performs various calculations and signal processing based on the control program shown in FIG. The output port device 74 controls the drive current supplied from the drive circuit to the auxiliary steering motor 22 by outputting a control signal to the drive circuit 38 in accordance with an instruction from the CPU 66, and outputs a control signal to the drive circuit 40 A drive current supplied from the drive circuit to the electromagnetic clutch 24 is controlled.

The electronic control unit for traveling 48 is also a microcomputer constructed similarly to the electronic control unit for auxiliary steering 28 described above, and includes a CPU 80 as shown in FIG.
ROM 82, RAM 84, input port device 86,
And an output port device 88, which are connected to each other by a bidirectional common bus 90. Although not shown in FIG. 2, the operating power of the electronic control unit 48 is also supplied from the auxiliary battery 32 via the DC / DC converter 34.

The input port device 86 has an SOC meter 56.
The signal indicating the voltage Vm of the main battery 46 and the signal indicating the depression amount of the accelerator pedal detected by the depression amount detection sensor 92 are input. The input port device 86 appropriately processes the signal input thereto, and in accordance with the instruction of the CPU 80 based on the control program stored in the ROM 82, the CPU and the RAM 7
4 to output the processed signal.

The ROM 82 stores an engine control program shown in FIG. 8 and a running control program not shown in the figure. The CPU 80 performs various calculations and signal processing based on these control programs as described later. It is supposed to do. The output port device 88 outputs a drive current to the drive motor 44 via the inverter 42 according to the instruction of the CPU 80, and outputs a starter signal to the starter motor 58 and the auxiliary steering electronic control device 28 when starting the auxiliary engine 60, A signal for controlling the switching is output to 36.

Next, the operation of the power steering apparatus in the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control by the electronic control unit 28 is started when an ignition switch (not shown) is closed. The flag Fst in the flowchart shown in FIG. 4 relates to whether or not the power supply to the auxiliary steering motor 22 is in a period during which the power supply should be stopped. It indicates that there is.

First, at step 10, a control signal is output to the electromagnetic clutch 24 via the drive circuit 40 to connect the clutch. At step 20, the steering torque T detected by the torque sensor 26 is indicated. Signal, signal indicating vehicle speed V detected by vehicle speed sensor 30, SO
A signal indicating the voltage Vs of the auxiliary battery 32 detected by the C meter 56 is read. In particular, when a starter signal is output from the electronic control unit 48 to the starter motor 58, the signal is also read.

In step 30, based on the steering torque T read in step 20, a basic assist amount Tab is calculated from a map corresponding to the graph shown in FIG.
In step 40, a vehicle speed coefficient Kv is calculated from the map corresponding to the graph shown in FIG. 6 based on the vehicle speed V read in step 20. In step 50, the assist amount Ta is calculated as the product of the basic assist amount Tab calculated in step 30 and the vehicle speed coefficient Kv calculated in step 40.

The calculation itself of the assist amount Ta in steps 30 to 50 does not constitute the gist of the present invention. The assist amount is calculated in an arbitrary manner as long as it is calculated at least according to the steering torque T. May be.

In step 60, it is determined whether or not a starter signal has been input. If the starter signal has not been input, the routine proceeds to step 80, and if the starter signal has been input, in step 70 the flag Fst Is 1
After the count value Tc of the timer is reset to 0, the routine proceeds to step 140. In step 80, it is determined whether or not the flag Fst is "1".
When it is determined that st = 0, step 12 is executed.
The routine proceeds to 0, and when it is determined that Fst = 1, the count value Tc of the timer is incremented by 1 in step 90, and then the routine proceeds to step 100.

In step 100, it is determined whether or not the count value Tc of the timer is equal to or more than a reference value Te (positive constant), that is, a period in which the suspension of the power supply to the auxiliary steering motor 22 is prohibited. It is determined whether or not Tc ≧ T
If it is determined that it is not e, step 140
When it is determined that Tc ≧ Te, the flag Fst and the count value Tc are reset to 0 in step 110, and then the process proceeds to step 140. Reference value
Te is used for starting the auxiliary engine 60 for the purpose of the present invention.
As a result, voltage Vs of auxiliary battery 32 temporarily drops.
Power supply to the auxiliary steering motor 22 for more than
The power supply is set to be prohibited and power supply is enabled.

In step 120, the auxiliary battery 32
Is determined whether or not the voltage Vs is equal to or higher than the reference value Vse (positive constant), that is, whether or not the voltage of the auxiliary battery is a voltage at which normal auxiliary steering can be performed.
If it is determined that .gtoreq.Vse, step 14 is executed.
When it is determined that Vs.gtoreq.Vse is not satisfied, in step 130, the power supply to the auxiliary steering motor 22 is stopped, the clutch 24 is released, and the power steering device is switched to the manual steering device. Can be

In step 140, a control signal corresponding to the assist amount Ta is output to the auxiliary steering motor 22 via the drive circuit 38, whereby the auxiliary steering force is controlled to a value corresponding to the assist amount Ta. Thereafter, the flow returns to step 20.

Next, the control of the power generation auxiliary engine in the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control by the electronic control unit 48 is also started by closing an ignition switch (not shown). The flag F in the flowchart shown in FIG. 8 relates to whether or not the auxiliary engine 60 is operating, and 1 indicates that the auxiliary engine is operating.

In step 210, the SOC meter 56
Is read, a signal indicating the voltage Vm of the main battery 46 detected is read, and in step 220, it is determined whether or not the voltage Vm is less than a reference value Vme (positive constant), that is, the voltage of the main battery is It is determined whether or not the voltage has dropped to a voltage at which the vehicle may not be able to travel normally, and Vm <
If it is determined that it is not Vme, step 25
0, and when it is determined that Vm <Vme, the routine proceeds to step 230.

In step 230, it is determined whether the flag F is 1 or not. If it is determined that F = 1, the process proceeds to step 210 while the operation of the auxiliary engine 60 is maintained. When it is determined that F = 1 is not satisfied, the starter signal is output to the starter motor 58 in step 240, so that the auxiliary engine 60
Is started and the flag F is set to 1, and the process returns to step 210. In step 250, the auxiliary engine is stopped or kept stopped, and the flag F
Is reset to 0.

Thus, according to the illustrated embodiment, the assist amount Ta is calculated in accordance with the steering torque T and the vehicle speed V in steps 30 to 50 of the auxiliary steering control.
In step 140, it is determined whether or not the voltage Vs of the auxiliary battery 32 is equal to or higher than the reference value Vse. If it is determined that Vs ≧ Vse and normal auxiliary steering can be performed, the routine proceeds to step 140. As a result, the assist steering force is controlled to a value corresponding to the assist amount Ta, whereby the steering assist force is controlled to correspond to the steering torque and to decrease as the vehicle speed increases, so that light steering in a low vehicle speed range is achieved. As well as good steering stability in a high vehicle speed range.

If the voltage Vs falls below the reference value Vse due to the power consumption of the auxiliary battery 32, there is a possibility that normal auxiliary steering cannot be performed due to insufficient voltage of the auxiliary battery. If the determination is no, the power supply to the auxiliary steering motor 22 is stopped and the clutch 24 is released in step 130, and the power steering device is switched to the manual steering device. Is reliably prevented.

Step 2 of controlling the auxiliary engine for power generation
When it is determined at step 20 that the voltage Vm of the main battery 46 has dropped below the reference value Vme, a starter signal is output to the starter motor 58 at step 240 to start the auxiliary engine 60 and generate power. Main battery 46 and auxiliary battery 32 are charged with electric power generated by electric machine 54. In this case, when the auxiliary engine 60 starts, the voltages of the two batteries temporarily decrease. In order to cope with this, in steps 60 to 110, T is set at a point in time when the auxiliary engine 60 is started by the electronic control unit 48 for traveling.
Until the time e has elapsed, the determination of the insufficient voltage of the auxiliary battery 32 in step 120 is prohibited, and thereby the execution of step 120 is prohibited.

Therefore, according to the illustrated embodiment, even if the voltage Vs of the auxiliary battery 32 drops below the reference value Vse, if the voltage Vs is temporary with the start of the auxiliary engine 60, step 120 is executed. This is reliably prevented from being carried out, thereby reliably preventing the power steering device from being unnecessarily switched to the manual steering device.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments may be made within the scope of the present invention. The possibilities will be clear to the skilled person.

For example, in the above-described embodiment, when the auxiliary engine 60 is started, the Tc time step 120
In this case, the stop of the power supply to the auxiliary steering motor 22 is prohibited by prohibiting the determination of the decrease in the voltage of the auxiliary battery 32 in FIG. Only when the voltage Vs of the engine battery 32 is less than the reference value Vse is it determined at step 80 whether or not the auxiliary engine 60 has been started. When the auxiliary engine has been started, the power is determined at steps 90 to 110. The processing for prohibiting the supply stop may be performed.

[0037]

As is apparent from the above description, according to the present invention, the auxiliary engine M3 is controlled by the start detecting means M7.
If the start of the engine is detected, the battery
Since the power supply stoppage by the power supply stop means is prohibited by the stop prohibition means M8 for a period of time equal to or longer than the temporary voltage drop time of the battery M1 , the generator M2 is driven and the battery M
When the engine is started to supply power to the power steering unit 1 and the voltage of the battery temporarily drops below a predetermined value, the supply of power from the battery to the power steering device M4 is stopped by the power supply stopping means M6. Therefore, it is possible to reliably prevent the power steering device from being unnecessarily switched to the manual steering device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an electric vehicle according to the present invention in correspondence with the description in the claims.

FIG. 2 is a schematic configuration diagram showing one embodiment of an electric vehicle according to the present invention including an electric power steering device.

FIG. 3 is a block diagram showing an electronic control unit for auxiliary steering shown in FIG. 2;

FIG. 4 is a flowchart showing a routine of auxiliary steering control achieved by the electronic control unit for auxiliary steering shown in FIGS. 2 and 3;

FIG. 5 is a graph showing a relationship between a steering torque T detected by a torque sensor and a basic assist amount Tab.

FIG. 6 is a graph showing a relationship between a vehicle speed V detected by a vehicle speed sensor and a vehicle speed coefficient Kv.

FIG. 7 is a block diagram showing the electronic control unit for traveling shown in FIG. 2;

FIG. 8 is a flowchart showing a control routine of a power generation auxiliary engine which is achieved by the traveling electronic control device shown in FIGS. 2 and 7;

FIG. 9 is a flowchart showing another embodiment of the auxiliary steering control routine achieved by the electronic apparatus for auxiliary steering shown in FIGS. 2 and 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Steering wheel 12 ... Steering shaft 22 ... Auxiliary steering motor 24 ... Electromagnetic clutch 26 ... Torque sensor 28 ... Auxiliary steering electronic control unit 30 ... Vehicle speed sensor 32 ... Auxiliary battery 44 ... Running motor 46 ... Main battery 48 ... Electronic control unit for traveling 54 ... Generator 56 ... SOC meter 60 ... Auxiliary engine

Continued on the front page (72) Inventor Takashi Iwasaki 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masaaki Tsuboi 1 Toyota Motor Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) Reference Document JP-A-6-191418 (JP, A) JP-A-3-227776 (JP, A) JP-A-63-43865 (JP, A) JP-A 63-4875 (JP, U) JP-A 64-64 1171 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 5/04

Claims (1)

(57) [Claims] 1. A power supply battery, a generator for supplying power to the battery, an auxiliary engine for selectively driving the generator, an electric power steering device using the battery as a power supply, and a voltage of the battery An electric vehicle comprising: voltage detection means for detecting the power supply; and power supply stopping means for stopping supply of power from the battery to the power steering device when the voltage of the battery falls below a predetermined value. Start detecting means for detecting the start of the engine, and when the start of the engine is detected.
The temporary charging of the battery due to the start of the engine
An electric vehicle comprising: a stop prohibition unit that prohibits a power supply stop by the power supply stop unit for a time equal to or longer than a voltage drop time .