JPS62166162A - Rear wheel neutral lock device of front and rear wheel steering device - Google Patents

Abstract

PURPOSE:To lock a rear wheel in a neutral position independently of a control route when a rear wheel steering route is abnormal by arranging a neutral restoration means for restoring the neutral position as well as a deviation detection means for detecting a deviation of the rear wheel steering means from the neutral position. CONSTITUTION:A neutral restoration means 20 for restoring a rear wheel to the neutral position is provided with a restoration cylinder 60 which drives a tie-rod 38r in a direction opposite to a side on which lock actuation switches 58R and 58L of a neutral lock device 18 have been actuated. Two routes of input signals detected with a front and a rear wheel steering angle sensors 28 and 44 are inputted to both a main computer 72 and a subcomputer 74 and the operated results are outputted to both a servomotor 42 of a rear wheel steering device 16 and a drive amplifier 56 of a neutral lock device 18. When both computers 72 and 74 are discriminated to be out of order, normal front and rear wheel steering is inhibited and restoration and lock to the neutral position as well as issuing warning are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a rear wheel neutral locking device for a vehicle with front and rear wheel steering.
In particular, the rear wheels of front and rear wheel steered vehicles are suitable for use in front and rear wheel steered vehicles of the so-called drive-by-wire system (hereinafter referred to as DEW system) in which the rear wheels are electrically and hydraulically steered by an electro-hydraulic system. Regarding improvement of wheel neutral lock device J-
Ru. [Conventional technology 1] For example, a DBW type front and rear wheel steering system (q!) in which multiple wheels are electrically and hydraulically steered using an electro-hydraulic system has been researched. In this DBW type front and rear wheel steering vehicle, Because the steering wheel operated by the Ministry of Driving and the rear wheel steering gear bucket are not mechanically connected, electrical noise, short circuits, disconnections,
It is necessary to have a complete fail-safe and backup mechanism against poor connector contact, computer failure, hydraulic system leaks, depressurization due to pump IG (D), inoperation due to actuator system failure, etc. For this purpose, various methods and gastric fillings have been proposed in the past; for example, the applicant has already proposed
64 proposes a rear wheel steering control device that limits the rear wheel steering angle at high speeds by protruding a stopper that reduces the movement of the hydraulic cylinder that steers the rear wheels at high speeds. In addition, Japanese Patent Application Laid-open No. 60-42161 discloses that when the front wheel steering angle detected by the front wheel steering angle sensor exceeds the allowable critical front wheel steering angle determined by the output from the vehicle speed sensor, the rear wheel steering angle is changed. The rudder angle was controlled to haze (neutral position) 4
A wheel steering device is disclosed. Furthermore, Japanese Patent Application Laid-open No. 60-78870 discloses a four-wheel steering system in which a sensor failure is determined from the state of change of at least one of a front wheel steering angle sensor and a vehicle speed sensor, and the steering angle of the engaged wheels is controlled to zero (2a). An apparatus is disclosed. [Problem to be Solved by the Invention 1] However, all of the above-mentioned conventional techniques had specific drawbacks and were not perfect. That is, the device proposed in Japanese Utility Model Application No. 60-150164 cannot detect abnormalities in various sensors or computers, and does not have the additional feature of restoring the rear wheels to a neutral position with zero steering angle. Furthermore, the device disclosed in Japanese Patent Application Laid-Open No. 60-42161 is
It is not possible to detect an abnormality in the computer, and the detection of an abnormality in the front wheel steering angle sensor is also insufficient. Furthermore,
The device disclosed in Japanese Patent Laid-Open No. 60-78870 cannot detect computer abnormalities. In addition, in any of the above devices, there is only one system of controllers such as actuators and computers that control the rear wheel steering angle, so if the actuator or controller breaks down, effective fail-safe processing cannot be performed. There were problems such as the inability to do so. On the other hand, Utility Model Showa 60-49072.60-92669.6
0-92670.60-92673, when the steering angle of the front wheels is small during high-speed driving, the front and rear wheel steering is stopped by fixing the rear wheels in a neutral position to prevent the rear wheels from wobbling. A device designed to prevent anxiety when driving at high speeds.
Further, a device has been disclosed that utilizes this device to continue locking the rear wheels when a sensor abnormality occurs. However, unlike the present invention, the 7-ail safe was not the main purpose and was not intended to be activated only in abnormal situations. [Objective of the Invention 1] The present invention has been made to solve the above-mentioned conventional problems.In the event of an abnormality in the rear wheel steering system, the rear wheels can be moved to the neutral position independently of the control system such as a computer. To provide a rear wheel neutral locking device for a front and rear wheel steered vehicle that can be restored and locked. (Means for Solving the Problems 1) The present invention provides a 19-wheel neutral locking device for a front single-wheel steering vehicle in which the rear wheels are electrically or electrically/hydraulicly steered, as shown in FIG. As shown in the summary structure, (a means for determining an abnormality in the rear wheel steering system, and a left and right system that is driven when an abnormality is determined by the abnormality determining means and locks the rear wheel steering means from both sides of the neutral position) and deviation direction detection means for detecting the direction of deviation of the rear wheel steering means from the neutral position based on the difference in the operating state of the left and right motion locking means, and The above object is achieved by including a neutral restoring means that gradually restores the rear wheels toward the neutral position using stored energy. Or, when locking the rear wheels of a vehicle with front and rear wheel steering that is electrically or hydraulically steered in the neutral position, if an abnormality in the rear wheel steering system is determined, the neutral locking means of the left and right systems are used to lock the rear wheels in the neutral position. In addition to locking the rear wheel steering means from both sides of the position (1), the direction of deviation of the rear wheel steering means from the neutral position is detected from the difference in the operating state of the left and right neutral locking means, and the deviation is eliminated. 9
In order to achieve this, the rear wheels are gradually restored toward the neutral position using energy stored in advance. Therefore, even if the computer is out of order when there is an abnormality in the rear wheel steering system, the rear wheels can be reliably restored to the neutral position and locked. [Embodiment 1] An embodiment of the control II device for a front and rear wheel steered vehicle according to the present invention (in which a central locking device for receiving wheels is adopted) will be described in detail below with reference to the drawings. As shown in FIG. 2, a front wheel steering device 12 for steering the right front wheel 10R and a left front wheel 10L, a rear wheel steering device 16 for steering the right front wheel 14R and the left rear wheel 14L, and a rear wheel steering device 16 for steering the right front wheel 10R and the left front wheel 10L, The front wheel steering device 12 mainly includes a neutral locking device 218 for locking at a neutral position δ with an angle of zero, and a neutral restoring device 20 for restoring the rear wheels to the neutral position. A steering wheel 22 that is steered by a person is provided.A steering shaft 24f that transmits the rotation of the steering wheel 22 to a front steering gear box 26 [of a rack-and-binion type, for example, is provided with a steering shaft 24f that has a front wheel steering angle. Two front wheel steering angle sensors 28 of the same configuration, which are divided into two systems for detecting δf, and a power steering valve 30f for switching the hydraulic pressure application direction of the power steering device are provided. The power steering device includes a front power steering oil tank 32f, a power steering pump 34 for pumping up oil from the oil tank 32, which is rotated using, for example, the rotational force of the engine, and the power steering oil tank 32f. The power steering cylinder 36 is supplied with oil pressurized by a steering pump 34f and whose supply direction is switched by the power steering valve 30F.The steering gear box 26 converts rotational motion to linear motion. The power that is converted and multiplied in the same direction by the power steering cylinder 36f, which is also recessed, is transmitted to the tie rod 38f.The tie rod 38f is connected to the right front wheel 10R and the left The front wheel 10L is steered.The rear wheel steering device 16 has substantially the same configuration as the front wheel steering device 12, and instead of the steering wheel 22, it includes a servo for rotating the steering shaft 24r of the steering wheel 22. The above-described feature is that a motor (a pulse motor may be used) 42 is provided, and a two-system rear wheel steering angle sensor 44 for detecting the rear wheel steering angle δr' is provided in the middle of the steering shaft 24r. It is different from the front wheel steering device 12.The other configuration is the same as the front wheel steering device 12, so instead of the subscript f, 1 flame wheel steering device 16 is used.
A subscript r indicating that it is a groove component search will be added, and the explanation will be omitted. In addition, the rear power steering pump 34r
and the oil tank 32r can also be shared with the front power steering pump 34 and the oil tank 32, respectively. The neutral locking device 18 includes a neutral locking stopper 50 disposed on the way from the rear wheel steering gear box 26r to the tie rod 38r. Near the neutral lock stopper 50, there is a neutral right lock 5 for clamping and fixing the stopper 50 from both sides at the neutral position.
2R and a neutral left lock 52L are provided respectively. The neutral locks 52R and 52L are caused to protrude to a position where they sandwich the stopper 50, or are retracted to a position where they do not interfere with the movement thereof, by operating solenoids 54R and 54L, respectively. The operating solenoid 54R154L
is energized by the drive amplifier 56 when the ignition switch is turned on and the contact of the ignition switch operating relay 57 is turned on, and is controlled to move up to the retracted position. This is to ensure safety when power is turned off due to failure. Each of the neutral locks 52R152L has a lock activation switch 58R1 that is turned on when the neutral lock 52R152L is in the protruding position.
Relays R1 and R2 operated by 58L are provided. The neutral one-party source device 20 includes the neutral lock device 18
A restoring cylinder 6 drives the tie rod 38r in the opposite direction to the side where the lock activation switches 58R and 58L are activated.
0 is provided. The control valve 62 for supplying hydraulic pressure to the restoring cylinder 60 allows the restoring cylinder 60 to move freely in the neutral position, and the third
At the right position in the figure, the tie rod 38r is displaced to the right in the figure, and at the left position, the hydraulic pressure is controlled so as to displace the tie rod 38r to the left. The hydraulic pressure supplied to this control valve 62 is pressurized by the rear power steering pump 34r, and the hydraulic pressure stored in the accumulator 66 is transferred via the check valve 64 to the throttle valve 68.
It is said to have been narrowed down by The neutral restoring device 20 is further provided with a power steering release solenoid valve 70 for stopping the operation of the rear power steering cylinder 36r when restoring to neutral. This power steering release solenoid valve 70 normally cuts off communication between the input port and the output port to allow the power steering cylinder 36r to operate normally, as shown in FIG. During the restoration operation when R2 is on, the second
By switching to the left position in the figure, the cylinders on both sides of the power steering cylinder 36r are brought into communication so that the operation of the restoring cylinder 60 is not hindered. The front wheel steering angle sensor 28 of the two systems, the contact wheel steering angle is determined by the holder 44.
The two systems of input signals detected by the above are input to the main computer 72 and the backup subcomputer 74, respectively. The main computer 72 and the subcomputer 74 each perform substantially the same calculation processing, and apply the calculation results to the servo motor 4 of the contact wheel steering device 16.
2. The signal is output to the drive amplifier 56 of the neutral lock device 7118, etc. The main computer 72 and sub-computer 74
are respectively constructed and connected as shown in FIG. That is, the main computer 72 and sub-computer 74 each have equivalent central processing units (CPUs) 72A and 74A that perform various arithmetic operations,
read-only memories (ROM) 72B, 74B for storing control programs, calculation data, etc. in advance;
Random access memories (RAM) 72G and 74C for temporarily storing FtAn data, etc., and signals input from the front wheel steering angle sensor 28, rear wheel steering angle sensor 44, vehicle speed sensor (not shown), etc. The output section 72E, 74E outputs a rear wheel steering angle command value δ, an abnormality judgment signal, a warning, etc. according to the output results of the CPUs 72A, 74A. The abnormality determination signal output from the main computer 72 is input to the input section 74D of the leave computer 74. Further, from the output section 74F of the subcomputer 74, a neutral restoration and lock signal is outputted to the drive amplifier 56. The operation of the embodiment will be explained below. The processing shown in the figure is performed. That is, first, in step 110, flags and counters are initialized. Next, the process proceeds to step 112, where the detected front wheel steering angle value δr input from the front wheel steering angle sensor 28, The rear wheel steering angle command value δr+ (subscript 1 is the Ω output value of the main computer 72 (indicates that the vehicle speed is V), then the - is detected.Next, the process proceeds to step 114, and the front wheel steering angle is determined based on the abnormality determination area set according to the vehicle speed V, as shown in FIGS. 5 and 6, for example. It is determined whether the detected value δ[, the rear wheel steering angle command value δrl, and the rear wheel steering angle detection f 15 r− are each in the normal range. In this step 114,
Due to electrical system causes such as disconnection, short circuit, sensor abnormality, poor contact, noise, etc., the front wheel steering angle δf, rear wheel steering angle command value δr, and rear wheel steering angle detected value δr' may reach a range where the vehicle does not steer at the vehicle speed V. When it grows up, it becomes different from abnormality. Note that since the rear wheel steering angle detection value δr' may become too large even if there is a failure in the hydraulic system, such an abnormality can also be detected. If all the determination results in step 114 are positive, the process proceeds to step 116, where the differential value δ of the front wheel steering angle detection value, the differential value δr I , i of the rear wheel steering angle command value. It is determined whether or not the differential value δ'- is normal, for example, because each satisfies the following relationship: 1δf 1≦α...(1) 1δr+l≦β...(2) 1δr' l≦β...(3) This step 116 detects disconnection, short circuit, sensor abnormality,
Front wheel steering angle detection value δf due to electrical system causes such as poor contact or noise.
, when the detected value δr' of the wheel steering angle immediately after the 1st wheel steering angle wheel gold angle command changes abnormally quickly, that is, the differential value δ[, δr,
It is determined that there is an abnormality when δr' is too large. J5, the differential value δr' of the detected value of the rear wheel steering angle can also become abnormally large due to a failure in the hydraulic system, so such a failure can also be detected. If all the determination results in step 116 are positive, the process proceeds to step 118, and the rear wheel steering angle command value δ is calculated using the following equation.
The absolute value of the difference between r1 and the detected rear wheel steering angle value δr' is within the abnormality determination area, which is set to change according to the speed of 1δr1.1δr=l, taking into account sudden response delays. Determine whether or not. I δr 1-δ-rl ≦7+k, l
δr+10k 21 δrl ・ (4) In this equation (4), the second and third terms on the right side are for considering the undesirable response delay, and γ, kl,
Each k3 is a constant. In general, in response to instructions for rear wheel steering angle, inertia of tires, etc.
Due to the limits of oil pressure and oil flow, the actual steering angle may be delayed, and slight deviations may occur due to the play and elasticity of the steering system, but this step 118 is intended to prevent failures in the mechanical system, electrical system, hydraulic system, etc. Therefore, if the detected value δr' significantly deviates from the indicated value δr, it is determined that there is an abnormality. If the determination result in step 118 is positive and it is determined that no abnormality has occurred in the main computer 72 and its sensor system, the process proceeds to step 122, where the rear wheel steering angle command value δr1 calculated by the main computer 72 is calculated. Front and rear wheel steering control 211 (4WS') is executed as the final rear wheel steering angle command 11αδr. Then step 12
4, information is output to the subcomputer 74 indicating that the main computer 72 is not malfunctioning and flag 1 has been reset. Next, the process proceeds to step 126, and the time Δ
After passing through L, the process returns to step 112 described above. On the other hand, if the judgment result in either step 114, 116 or 118 is negative, and it is judged that an abnormality has occurred in the main computer 72 or its sensor system, the process proceeds to step 130 and flag 1 is set. do. Next, the process proceeds to step 132, where "?JtH" is turned on.Next, the process proceeds to step 134, where the rear wheel steering angle command value δ is set.
Control using the output value δr1 of the main computer 72 as r is stopped. The process then proceeds to step 136, where information that flag 1 is set is output to the subcomputer 74. On the other hand, the processing in the subcomputer 74 is carried out by the seventh
It is executed according to the flowchart shown in the figure. In this routine, the main computer 7 shown in FIG.
Steps that are the same as or similar to those in Step 2 are given the same reference numerals and their explanations will be omitted. Note that the subscript 2 attached to the rear wheel steering angle command 1 straight δr and its differential value δr2 indicates that these are calculated values by the subcomputer 74. Further, flag 2 is a flag indicating that the subcomputer 74 or its sensor system is abnormal. If the determination result in step 118, which is similar to the routine shown in FIG. 4 above, is positive, this subcomputer 7
Proceeding to step 210 specific to 4, it is determined whether flag 1 is set. When the determination result is positive and it is determined that the system of the main computer 72 is abnormal, the process proceeds to step 212, and the rear wheel steering angle command value δr2 calculated by the subcomputer 74 is set to the @Hiragi rear wheel steering angle command value δr2. The 4WS formation is executed using the angle command value δr. After step 212 is completed, or if the judgment result in step 210 is negative, the main computer 7
When it is determined that the system No. 2 is normal, the process proceeds to step 214, and after Δ seconds have elapsed, the process returns to step 112, which is similar to the routine shown in FIG. On the other hand, step 1, which is similar to the routine shown in FIG.
After completing step 32, the process proceeds to step 220, where it is determined whether flag 1 indicating an abnormality in the system of the main computer 72 is set. If the determination result is positive and it is determined that both the main computer 72 and subcomputer 74 systems are abnormal, the process proceeds to step 222, where the rear wheel steering angle command value δr is set to zero and normal 4WS control is stopped. At the same time, a neutral lock signal is output to the drive amplifier 56 of the neutral lock device 18, and the computer 72 is activated by the neutral lock device 18 and the neutral 1u source device 22.
Alternatively, the rear wheels are restored to the neutral position and locked independently without depending on the control command 74. Specifically, when the excitation signals of the operating solenoids 54R and 54L are both turned off by the output of the drive amplifier 56,
Both neutral locks 56R and 56L are about to protrude downward in the figure. At this time, if the rear wheels are in the neutral position with zero steering angle and the neutral lock stopper 50 is located exactly between the neutral locks 52R and 52L as shown in FIG. 2, the neutral lock 52R152L will protrude as is. By sandwiching the neutral locking stopper 50 from both sides, the rear wheel steering angle is fixed at the neutral position. At this time, relays R+ and R2 are both turned on, so the control valve 62 of the restoration cylinder 60 and the power steering release solenoid valve 70
maintains the state shown in FIG. On the other hand, the rear wheel steering angle is not zero, and the neutral lock stopper 50
is shifted, for example, to the right in the figure, only the left neutral lock 52L protrudes and relay R2 is turned on, whereas the right neutral lock 56R protrudes from the stopper 50.
Since it hits, it cannot eject, and relay R1 remains off. Therefore, the control valve 6 of the restoration cylinder 60
2 is in the state on the left side in FIG. 2 to drive the rear wheels toward the neutral position, and the hydraulic pressure stored in the accumulator 66 is gradually supplied to the right side of the restoring cylinder 60 via the flow limit valve 68. Ru. At this time, since only relay R2 of the power steering release solenoid valve 70 is turned on, the left side position in the figure is selected, and both sides of the power steering cylinder 36r are communicated, and the oil pressure applied to the power steering cylinder 36r is restored. cylinder 60
This is done so as not to interfere with the production of 0J. Therefore, the rear tie rod 38r moves slowly to the left in the figure without causing any discomfort in the vehicle's behavior.
The stopper 50 also moves to the left in the figure and protrudes at a position 7.7 at which the right neutral lock 52R can be protruded. Therefore, the rear wheel steering angle is locked at the neutral position, and the control valve 62 and power steering K l
The rl solenoid valve 70 returns to its original state. Note that if the rear wheel is turned in the opposite direction and the neutral lock stopper 50 is shifted to the left from the neutral position in the figure, the locks and solenoids that operate will be reversed left and right, but the basic operation will be the same. Since they are the same, their explanation will be omitted. As described above, if both the main computer 72 and the drive computer 74 are normal, the normal front wheel change is performed, the 'I'1 tll occurs, or the neutral recovery lock is activated. On the other hand, if a failure is detected in either the main computer 72 or the nub computer 74, normal front and rear wheel steering will continue and a warning will be generated.In this case as well, the neutral position However, if both the main computer 72 and subcomputer 74 are determined to be malfunctioning, normal front and rear wheel steering is prohibited, a warning is output, and the neutral In this embodiment, an abnormality in the rear wheel steering system is detected by either the detected value of the front wheel steering angle, the command value of the rear wheel steering angle, or the detected value.
Is it in the abnormality determination area set according to the vehicle speed, or
Either the front wheel steering angle detected value, the rear wheel steering angle instruction value, or the differential field of the rear wheel steering angle detected value is within the abnormality judgment range, or the difference between the command value and the detected value of the rear wheel steering angle is sudden. Since the system detects the presence of an abnormality in the abnormality determination area, which takes into account the delay in response, it is possible to reliably detect abnormalities in the rear wheel steering system and perform appropriate fail-safe processing. I can do it. Note that the method for determining an abnormality in the rear wheel steering system is not limited to this. Furthermore, in this embodiment, two sensor and computer systems are provided independently of each other, and the rear wheels are restored to the neutral position and locked only when an abnormality in both systems is detected at the same time. Therefore, if either system fails, normal rear wheel steering can be performed, dramatically increasing the reliability of front and rear wheel steering. Note that the configuration of the sensors and computer for steering the front and rear wheels is not limited to this, and only one system may be used. Also, the warning may be omitted. [Effects of the Invention] As explained above, according to the present invention, when there is an abnormality in the rear wheel steering system, the rear wheels are reliably restored to the neutral position and locked at the neutral position, regardless of the failure state of the computer. be able to. Also, when restoring the rear wheels to the neutral direction,
Since energy stored in advance is used, even if a hydraulic power source such as a hydraulic pump fails, it can be reliably restored. Furthermore, since the rear wheels are gradually restored toward the center position using a throttle or the like, it has excellent effects such as being able to return to the neutral position without causing any discomfort to the vehicle behavior.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main structure of a rear wheel neutral locking device for a front and rear wheel steered vehicle according to the present invention, and FIG. 2 is a block diagram showing an embodiment of a control device for a front and rear wheel steered vehicle to which the present invention is adopted. Figure 3 is a plan view showing the overall configuration and includes a partial block diagram.
FIG. 4 is a block diagram showing the individual configurations and connection states of the main computer and sub-computers used in the embodiment, FIG. 4 is a flowchart showing the processing procedure of the main computer, and FIG. FIG. 6 is a diagram showing the abnormality determination area of the front wheel steering angle detection value used in the example, and FIG. 7 is a diagram showing the abnormality determination area of the rear wheel steering angle command value and the detected value. , is a flowchart showing the processing procedure of the subcomputer. 14... Rear wheel, 16... Rear wheel steering device, 18... Neutral lock device, 20... Neutral restoring device, 36r... Rear power steering cylinder, 42...
...Servo motor, 50...Stopper for neutral lock, 52R152L...Neutral lock, 54R, 54L...Solenoid for operation, 56...Drive amplifier, 60...Cylinder for restoration, 62... Control valve, 64... Check valve, 66... Accumulator, 68... Flow restrictor valve, 70... Power steering release solenoid valve,
72.74...Computer.

Claims (1)

[Claims] (1) In a rear wheel neutral locking device for a front and rear wheel steered vehicle in which the rear wheels are electrically or electrically/hydraulicly steered, a means for determining an abnormality in the rear wheel steering system, and a means for determining an abnormality by the abnormality determining means. Due to the difference in the operating state of the left and right neutral locking means, which are activated when the left and right neutral locking means are activated and lock the rear wheel steering means from both sides of the neutral position, the rear wheel steering means deviation direction detection means for detecting the direction of deviation from the neutral position; neutral restoring means for gradually restoring the rear wheels toward the neutral position using energy stored in advance in order to eliminate the deviation; A rear wheel neutral locking device for a vehicle with front and rear wheel steering, characterized by comprising: