JPS61257368A - Control device for car with rear wheel steering control device - Google Patents

Abstract

PURPOSE:To prevent an unstable car from running at the same speed when a rear wheel steering mechanism fails by decreasing the car speed when the difference between the determined steering angle ratio and detected preset steering angle ratio is larger than a predetermined value. CONSTITUTION:A steering angle determining means 2 determines the steering angle ratio controlling rear wheels in the reverse phase with front wheels when the car speed is low and determines the steering angle ratio controlling rear wheels in the same phase as front wheels when the car speed is high. On the other hand, a preset steering angle ratio detecting means 6 detects the steering angle ratio set by a rear wheel steering mechanism 4. A deceleration control means 5 decreases the car speed when the difference between the determined steering angle ratio and detected preset steering angle ratio is not within a tolerance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention changes the steering angle ratio of the rear wheel steering angle to the front wheel steering angle (simply referred to as steering angle ratio in this specification) in accordance with the vehicle speed. The present invention relates to a control device for a vehicle equipped with a rear wheel steering control device.

[Prior art]

Conventionally, this type of technology has been disclosed, for example, in Japanese Patent Application Laid-Open No. 59-81272.
As shown in Japanese Patent Application Publication No. 59-81273, when the vehicle is running at low speed, the steering angle ratio is set so that the rear wheels are steered in the opposite phase to the front wheels, thereby enabling the vehicle to turn in a small radius. Furthermore, when the vehicle is running at high speed, the steering angle ratio is set so that the rear wheels are steered in the same phase as the front wheels, so that the vehicle can quickly change lanes.

[Problems to be solved by the invention C] However, in the above-mentioned device, while the vehicle is running,
If the rear wheel steering mechanism malfunctions and the driver continues to drive the vehicle without noticing the malfunction, the rear wheels will be steered regardless of the driver's intention, resulting in a worsening of the vehicle's steering stability.
The direction of travel of the vehicle may become unstable.

In order to solve the above-mentioned problem, an object of the present invention is to detect an abnormality occurring in the rear wheel steering mechanism by observing the setting state of the steering angle ratio of the rear wheel steering mechanism, and to decelerate the vehicle when an abnormality is detected. It is an object of the present invention to provide a control device for a vehicle equipped with a rear wheel steering control device that ensures safe driving.

[Means for solving problems]

In solving this problem, the structural features of the present invention, as shown in FIG. 1, include vehicle speed detection means 1 for detecting vehicle speed;
Based on the detected vehicle speed, a steering angle ratio is determined to control the rear wheels to be in phase opposite to the front wheels when the same vehicle speed is low, and to control the rear wheels to be in phase with the front wheels when the detected vehicle speed is high. a steering angle ratio determining means 2 for determining the determined steering angle ratio; an output means 3 for outputting a control signal corresponding to the determined steering angle ratio; and a rear wheel steering unit for setting the rear wheel steering angle to the determined steering angle ratio in accordance with the control signal. In a vehicle equipped with a rear wheel steering control device having a rudder mechanism 4 and a deceleration control means 5 for reducing vehicle speed, the rear wheel steering mechanism 4
a set steering angle ratio detecting means 6 for detecting the set steering angle ratio; and a determining means for determining whether the difference between the determined steering angle ratio and the detected set steering angle ratio is within a predetermined tolerance range. 7, and when the difference is not within the allowable range, the deceleration control means 5 reduces the vehicle speed.

[Effect]

In the present invention configured as described above, the rear wheel steering mechanism 4 sets the rear wheel steering angle to the steering angle ratio determined by the steering angle ratio determination means 2, and the set steering angle ratio is detected by the set steering angle ratio. Means 6
The determination means 7 determines whether the difference between the determined steering angle ratio and the detected set steering angle ratio is within a predetermined tolerance range. Can detect abnormal conditions. When this abnormality is detected, that is, when the difference between the determined steering angle ratio and the detected set steering angle ratio is larger than a predetermined value, the deceleration control means 5 acts to reduce the vehicle speed. If a failure occurs,
Vehicles that have become unstable due to poor handling stability due to this failure will no longer be allowed to continue running.
Vehicle running safety can be improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a front wheel steering mechanism 20 of a vehicle to which the present invention is applied;
Rear wheel steering mechanism 30, internal combustion engine 40, and rear wheel steering mechanism 3
0 and an electric control device 50 for controlling the internal combustion engine 40.

The front wheel steering mechanism 20 includes a pinion and lunk mechanism 21 and a pair of left and right relay rods 22a and 22b connected to a rack portion of the mechanism 21. The pinion and rack mechanism 21 is connected at its pinion portion to a steering handle 24 via a steering shaft 23.
The rotational motion of the relay rods 2'la and 22b is converted into reciprocating motion of the relay rods 2'la and 22b. The left and right relay rods 22a and 22b are the left and right tie rods (not shown) and the left and right knuckle arms 2.
5a, 25b to the left and right front wheels 26a, 26b, respectively, to steer the left and right front wheels 25a, 26b.

The rear wheel steering mechanism 30 includes a swing lever 32 for steering the rear wheels 31a, 31b in conjunction with the steering of the front wheels 26a, 26b.
A linear actuator 33 for displacing the movable fulcrum 32a of the swing lever 32, left and right rear wheels 31a,
31b is provided. The swing lever 32 includes a fixed point 32b to which a front connecting loft 35 connected to the left knuckle arm 25a is pivoted, and a fixed point 32c to which a rear connecting rod 36 is pivoted, and a movable fulcrum 3.
2a is between the fixed points 32b and 32c, the fixed point 32c is displaced in the opposite direction to the fixed point 32b, and when the movable fulcrum 32a is on the opposite side of the fixed point 32b to the fixed point 32c, The fixed point 32c is displaced in the same direction as the fixed point 32b, and if the movable fulcrum 32a is above the fixed point 32c, the fixed point 32c is not displaced,
He is trying to set a steering angle ratio by the position of the movable fulcrum 32a. The linear actuator 33 includes an actuator rod 33a connected to a movable fulcrum 32a.
A rear connecting rod 36 is connected to the left knuckle arm 37a, and the swinging of the swinging lever 32 steers the rear wheels 31a and 31b.

The internal combustion engine 40 includes an engine body 41, an intake pipe 42 and an exhaust pipe 43 connected to the engine body 41, and a fuel injection valve 44 that injects fuel into the intake pipe 42. Fuel pumped up from a fuel tank 46 by a fuel pump 45 via a conduit P1 is supplied to the fuel injection valve 44 via a conduit P2.
energization is controlled, and an amount of fuel proportional to the energization time is injected into the intake pipe 42 within the intake pipe 42. The injected fuel passes through an air cleaner intake valve 47 connected to the intake pipe 42.
The engine body 41. is supplied to the combustion chamber 41a.

Exhaust gas generated by combustion in the combustion chamber 41a is discharged to the exhaust pipe 43 via the exhaust valve 48. Note that the reference numeral 41b indicates a piston, and the reference numeral 4IC indicates a spark plug.

The electric control device 50 includes a vehicle speed sensor 51 that picks up the rotation of the output shaft of the transmission and generates a pink-up signal with a frequency corresponding to the vehicle speed, and a linear actuator rod 3.
3, that is, the current position of the movable fulcrum 32a, and generates an analog signal indicating a voltage value corresponding to the current steering angle ratio set by the swing lever 32.
2, a microcomputer 53 that calculates a target steering angle ratio and fuel injection valve 440 energization time by executing a program to be described later, and a linear actuator 33 based on signals provided from the vehicle speed sensor 51 and position sensor 52. A differential amplifier 54 is provided.

The microcomputer 53 includes a read-only memory (hereinafter simply referred to as ROM) 53a that stores programs corresponding to the flowcharts shown in FIGS. 3 and 5 and parameters for determining the steering angle ratio K, and a central processing unit that executes the programs. A device (hereinafter simply referred to as CPU) 53b,
Writable memory (hereinafter simply referred to as RAM) 53 that temporarily stores variables and flags necessary for this program
c, an input/output interface (hereinafter simply referred to as Ilo) 53d that exchanges data with an external circuit, and these ROM 53a, CPU 53b, RAM 53C and l10.
53d, and a bus 53e that commonly connects the buses 53d. The waveform shaper 51a converts the pickup signal from the vehicle speed sensor 51 into a rectangular wave signal and supplies the vehicle speed signal to the microcomputer 53, and the waveform shaper 51a converts the analog signal from the position sensor 52 into a digital signal and outputs the vehicle speed signal to the microcomputer 53. An analog-to-digital converter (hereinafter simply referred to as an A/D converter) 52 a and a microcomputer 53 convert the digital signal indicating the target steering angle ratio calculated into an analog signal to the first differential amplifier 54 . A digital analog converter (hereinafter simply referred to as a D/A converter) 55 supplied to the input end 54a and digital data indicating the energization time of the fuel injection valve 44 calculated by the microcomputer 53 are input, and the data is proportional to the energization time. a pulse generator 56 that supplies a pulse signal having a pulse width of 0.05 to the fuel injection valve 44; and a warning lamp 57 provided near the driver's seat to notify the driver of the malfunction when an abnormality occurs in the rear wheel steering mechanism 30. are connected. The differential amplifier 54 connects the position sensor 5 at its second input terminal 54b.
2 is connected, and the actuator rod 33a is driven to displace the movable fulcrum 32a until the voltage values applied to the first input end 53a and the second input end 53b match. This allows the swing lever 32 to set the target steering angle ratio.

The operation of the control device for a vehicle equipped with the rear wheel steering control device configured as described above will be explained using the flowcharts of FIGS. 3 and 5.

When the ignition switch is closed to start the vehicle, the electric control device 50 starts operating, the microcomputer 53 executes the main program (FIG. 3) to set the steering angle ratio, and the main program is executed. Meanwhile, fuel supply to the engine body 41 is controlled by executing an interrupt control program (FIG. 5) in synchronization with a signal from an engine rotation sensor (not shown) that picks up the rotation of the crankshaft. In the main program, the CPU 53b starts executing the program in step 60, initializes the fuel cut flag FC that controls the stop of fuel supply to "O" in step 60a, and outputs the signal from the vehicle speed sensor 51 in step 61. Waveform shaper 51
A vehicle speed U is calculated based on the vehicle speed signal supplied via
is calculated based on the steering angle ratio characteristic graph shown in FIG. 4 and temporarily stored in the RAM 53c. In this characteristic graph, the target steering angle ratio is set to be negative when the vehicle speed U is small, and is set to continuously change from negative to positive as the vehicle speed U increases.

Note that a negative (or positive) steering angle ratio means that the rear wheels are controlled in opposite phase (or in phase) with respect to the front wheels.

Next, in step 63, the CPU 53b outputs digital data representing the target steering angle ratio K to the D/A converter 55. This digital data is converted by the D/A converter 55 into an analog signal indicating a voltage value corresponding to the target steering angle ratio K, and is supplied to the first input terminal 54a of the differential amplifier 54. Since the differential amplifier 54 is supplied with an analog signal indicating a voltage value corresponding to the current steering angle ratio from the position sensor 52 to its second input terminal 54b, the differential amplifier 54 controls the linear actuator 33 to adjust the current steering angle ratio to the target value. The movable fulcrum 32a of the swing lever 32 is displaced until it matches the steering angle ratio.

In this manner, when the swing lever 32 sets the rear wheels 31a and 31b to the target steering angle ratio K, the front wheels 26a+2
6b is steered, this steering force is applied to the left knuckle arm 25.
a. Forward connecting rod 35. Swing lever 32. Rear connecting rod 36, left knuckle arm 37a, relay rod 34
and is transmitted to the right knuckle arm 37b, and the rear wheel 31a
, 31b are steered to the target steering angle ratio K.

After setting the target steering angle ratio, the CPU 53b executes step 6.
4, the current steering angle ratio set by the linear actuator 33 is input as the set steering angle ratio K'' from the position sensor 52 via the A/D converter 52a. is delayed by the time necessary to move the movable fulcrum 32a by servo control of the linear actuator 33, position sensor 52, and differential amplifier 54 after outputting the target steering angle ratio in step 63. After inputting 1 to the ratio, the CPU 53b compares this set steering angle ratio' with the target steering angle ratio calculated in step 62 in step 65, and calculates the both steering angle ratio K.

If Ko is equal, it is determined that there is no abnormality in the rear wheel steering mechanism 30, and the fuel is cut off in step 66.

The steering flag FC is set to 0'', and the cyclic calculations in steps 61-66 are continued to set the steering angle ratio to the target steering angle ratio K corresponding to the vehicle speed U. , ni' is compared to both steering angle ratios depending on the display bit number of the A-D converter 52a and the microcomputer 53.
A match will be determined when K" are approximately equal.

During the above-described cyclic operations in steps 61 to 66, when an interrupt command is output from the interrupt control circuit (not shown) in synchronization with the rotation of the engine, the CPU 53b executes step 7.
The calculation of the interrupt routine starts from 0. CPU53
b is the fuel cut flag FC at step 71.
It is determined whether or not an abnormality has occurred in the rear wheel steering mechanism 30.

When no abnormality has occurred in the rear wheel steering mechanism 30, the fuel cut flag FC is set to "0" in step 66 of the main program, so the determination in step 71 is rNOJ, and the process proceeds to step 72. Proceed with the interrupt control program.

In step 72, the CPU 53b calculates the engine speed based on the detection signal from the engine speed sensor (not shown), takes in intake air amount data from the intake air amount sensor (not shown), and calculates the engine speed and intake air amount. The energization time T of the fuel injection valve is calculated according to the value. The energization time control signal representing the energization time T is output to the pulse generator 56 in step 73, and the pulse generator 56 generates a pulse signal with a pulse width equal to the energization time T to the fuel injector 44 according to the energization time control signal. Output to. The solenoid coil inside the fuel injection valve 44 is excited by the pulse signal and attracts the plunger for the energization time T, so that an amount of fuel proportional to the energization time T is injected into the intake pipe 42. This injected fuel is combusted in the combustion chamber 41a, and the combustion drives the piston 41b, allowing the vehicle to travel.

Thereafter, the interrupt control program proceeds to step 74;
The CPU 53b again executes the above-mentioned cyclic operation of the main program.

As described above, if no abnormality has occurred in the rear wheel steering mechanism 30, the CPU 53b adjusts the rear wheel steering angle to the vehicle speed U by the cyclic calculation in steps 61 to 66 of the main program.
Since the fuel is controlled to the target steering angle ratio K which changes according to the steering angle ratio K, and the fuel is controlled to be supplied to the engine main body 41 by calculations in steps 70 to 74 of the interrupt control program, the vehicle can run normally by taking advantage of the function of the front and rear wheel steering vehicle. can do.

On the other hand, if an abnormality occurs in the rear wheel steering mechanism 30, the steering angle ratio K is determined in step 65 during the cyclic calculation of steps 61 to 66 of the main program.

It is determined that K' are not equal. As a result, the main program advances to step 67, and the CPU 53b sets the fuel cut flag FC to "1" in step 67, and lights up the warning lamp 57 in step 68, thereby causing an abnormality in the rear wheel steering device 30. After informing the driver of this, the cyclic operations of steps 61 to 65, 67, and 68 are executed.

In addition, as described above, in the both steering angle ratio in step 65,
If it is determined that ' is not equal to ', the CPU 53
In step b, execution of the main program may be terminated after the warning lamp is turned on in step 68.

Under the above conditions, when an interrupt command is issued and the execution of the interrupt control program starts from step 70, the fuel cut flag FC is set to 1'', so the CPU 53b outputs rYEs at step 71.
J is determined, and the execution of the interrupt control program is ended in step 74. As a result, steps 72 and 73 are no longer executed, and the pulse signal is no longer generated from the pulse generator 56, so fuel is no longer supplied to the engine body 41, combustion in the engine body 41 is stopped, and the internal combustion engine 40 is stopped.
will no longer generate driving force for the vehicle.

As described above, if an abnormality occurs in the rear wheel steering mechanism 30, a warning lamp can be turned on by executing step 68 of the main program to notify the driver of the abnormality, and step 72 of the interrupt control program can be executed. By not executing .73, fuel supply to the engine body 41 is prohibited, and the vehicle in which the abnormality has occurred can be automatically stopped.

As can be understood from the above explanation of the operation, in this embodiment, if an abnormality occurs in the rear wheel steering mechanism 30 of the front and rear wheel steering vehicle, the driver can turn on the warning lamp to control the rear wheel steering 8t130. Since the abnormality can be recognized, and the driver is prohibited from continuing to drive without noticing the abnormality of the vehicle, and the vehicle is promptly stopped, the safety of the vehicle can be improved. In addition, in this embodiment, since abnormality detection and processing in the case of abnormality in the rear wheel steering mechanism 30 are performed by electrical control means, there is no need to consider spatial issues compared to a method using mechanical means. The device according to this embodiment can also be installed in a vehicle, and the microcomputer, fuel injection valve, etc. already installed in the vehicle can be used as the electrical control means, so the cost of implementing the device according to this embodiment in the vehicle can be reduced. It can be realized.

Next, a modified main program that is a partial modification of the main program shown in FIG. 3 will be explained. The flowchart in FIG. 6 shows the modified main program,
Steps having the same functions as those of the main program in FIG. 3 are given the same reference numerals and their explanations will be omitted.

In this modified main program, the CPU 53b calculates Kl as the target steering angle ratio for two steering angle ratios using different methods based on the vehicle speed U in step 62a, and calculates Kl as the target steering angle ratio in different ways based on the vehicle speed U. .

Compare K1. If Kl is equal to both steering angle ratios,
As in the previous embodiment, the rear wheel turning angle is set to the target steering angle ratio K by the calculation in step 63, but if KL is not equal to both steering angle ratios, it is determined that an abnormality has occurred in the microcomputer 53. Then, in step 67, the fuel cut flag FC is set to "1", and in step 68, a warning lamp is turned on. As a result, the driver can recognize an abnormality in the microcomputer 53 by lighting the warning lamp 57, and even when an abnormality occurs in the microcomputer 53, the vehicle will be able to Since the operation is stopped by executing the interrupt control program shown in FIG. 5, the safety of running the vehicle is increased. In addition,
Both steering angle ratios according to different methods in step 62a above,
An operation of 1 means the following operation.

(11 Target steering angle ratio K on the different time side using the same calculation means.

Perform K1 calculation (this also includes cases where it is performed continuously).

(2) Calculate the target steering angle ratio K by substituting the vehicle speed U into a function representing the target steering angle ratio K with respect to the vehicle speed U, or specify an address by the vehicle speed U to a table that stores the target steering angle ratio K with respect to the vehicle speed U. The target steering angle ratio K is calculated using the equal steering angle ratio K.
Different calculation methods are used to calculate l.

(3) A plurality of microcomputers are provided, and each microcomputer independently calculates the steering angle ratio and Kl.

Furthermore, in this embodiment, there are two target steering angle ratios K.

I tried to calculate K1, but the microcomputer 5
In order to improve the accuracy of abnormality detection in step 3, the calculated number may be further increased.

In addition, in this modified main program, in the comparison calculation between the set steering angle ratio ° and the target steering angle ratio in step 65a, the set steering angle ratio K'' and the target steering angle ratio are 1 α≦ and ′≦ It is determined whether there is a relationship of +α. However,
The constant α is the steering angle ratio K.

It is a small positive value with respect to Kl. Based on this comparative judgment,
The CPU 53b determines that the rear wheel steering mechanism 30 is normal if the steering angle ratio Kl is in the above relationship, and determines that the rear wheel steering mechanism 30 is abnormal if the relationship is not in the above relationship. In this way, by giving a width to the comparative judgment of Kl in both steering angle ratios using the constant α, it is possible to prevent malfunction of the present device due to a detection error of the set steering angle ratio K'' and to adjust the steering angle ratio setting of the linear actuator 33. Malfunctions of the device due to time delays can be prevented.

Next, a modified interrupt control program that is a partial modification of the interrupt control program shown in FIG. 5 will be explained. The flowchart in FIG. 7 shows the modified interrupt control program, and has the same function as the interrupt control program shown in FIG. The same reference numerals are given to the steps, and the explanation thereof will be omitted.

In this modified interrupt control program, the CPU 53
b starts executing the calculation from step 70, and if there is no abnormality in the rear wheel steering mechanism 30, the fuel cut flag FC is set to "O", so step 7
0, 7.2, 71.75.73.74 are executed, and fuel is injected from the fuel injection valve 44. Step 7 above
In calculation No. 5, the CPU 53b sets the fuel reduction counter value TK to a constant C. This fuel reduction counter value T
K is for gradually reducing the amount of fuel supplied to the engine body 41 when an abnormality occurs in the rear wheel steering mechanism 30.

If an abnormality occurs in the rear wheel steering mechanism 30, the fuel cut flag FC is set to 1'' in the main program shown in FIG. 3 or the modified main program shown in FIG. rYEsJ, and advances the modified interrupt control program to step 76.The CPU 53b sets the fuel reduction counter value TK to the constant C in step 75 when the abnormality of the rear wheel steering mechanism 30 has just occurred. Step 76
At rNOJ, that is, the fuel decrease counter value TK is "0".
If not, the modified interrupt control program proceeds to steps 77, 78, and 73.

In step 77, the CPU 53b can stop the vehicle on the left side of the road with a margin while the fuel depletion cow is decreasing, thereby increasing the safety of the traveling vehicle.

Furthermore, in the above modification, the CPU 53b may output the power to the control circuit, and the control circuit may control the energization time T to gradually decrease.

Further, in the above embodiment, the characteristic graph showing the engine main body 2 is used to decelerate and stop a vehicle in which the rear wheel steering mechanism 30 has failed, and FIG. 5 is a flowchart corresponding to the microcontroller shown in FIG. 2.

Explanation of the symbols: 52...Position sensor, 53...Microcomputer, 57...Warning lamp.

Claims (1)

[Claims] a vehicle speed detecting means for detecting vehicle speed; and determining a steering angle ratio for controlling the rear wheels in a phase opposite to the front wheels when the detected vehicle speed is low based on the detected vehicle speed, and controlling the rear wheels to the front wheels when the detected vehicle speed is high. a steering angle ratio determination means for determining a steering angle ratio to be controlled in the same phase with respect to the determined steering angle ratio; an output means for outputting a control signal corresponding to the determined steering angle ratio; A set steering angle ratio that detects the steering angle ratio set by the rear wheel steering mechanism in a vehicle equipped with a rear wheel steering control device having a rear wheel steering mechanism that sets a steering angle ratio, and a deceleration control means that reduces vehicle speed. a detecting means and a determining means for determining whether or not the difference between the determined steering angle ratio and the detected set steering angle ratio is within a predetermined tolerance range; A control device for a vehicle equipped with a rear wheel steering control device, characterized in that the vehicle speed is reduced by deceleration control means.