JPS61295176A - Four-wheel steering gear - Google Patents

Abstract

PURPOSE:To avoid the risk which is caused by not enabling to confirm that rear wheels direct to what direction in starting by automatically returning the turn steering angle of the rear wheels to 0 in interlocking with the OFF operation of an ignition switch. CONSTITUTION:A first relay switch 42 selecting the ON state and the OFF state which cause an accessory switch 41 to by-pass and cause it not to by-pass is provided parallel to the accessory switch 41, respectively, and the first relay switch is controlled to the ON . OFF state by the controller 11. A second switch 45 selecting the similar ON . OFF states is also provided parallel to an ignition switch 44 which is interposed in a power line 43 for a starter. In stopping a vehicle, when a key is turned to operate the ignition switch 44 and the accessory switch 41 to the OFF state, the controller 11 controls the turn steering mechanism 10 of rear wheels so as to return the turn steering angle of the rear wheel 34 to 0.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a four-wheel steering device that is configured to steer not only the front wheels but also the rear wheels by steering operation. corner to 0
This invention relates to improvements that have been made so that the feeling of the vehicle does not feel strange when starting the vehicle when re-boarding the vehicle. 2. Description of the Related Art The idea of steering not only the front wheels but also the rear wheels in a predetermined direction according to a steering operation is already known, mainly for the purpose of improving running stability. For example, in the system disclosed in Japanese Patent Application Laid-Open No. 58-20563, a pinion attached to the front end of a shaft for transmitting operating force extending to the rear of the vehicle body is engaged with a rack rod in a steering gear box for the front wheels. The rotation of the force transmission shaft is input to the rear wheel steering mechanism to steer the rear wheels in a predetermined direction. In other words, the four-wheel steering device disclosed in this publication is configured to mechanically transmit a part of the steering force for steering the front wheels to the rear wheel steering mechanism. The steering angle is determined according to the steering angle of the front wheels. On the other hand, the system disclosed in Japanese Patent Application Laid-Open No. 59-77968 inputs input signals from a vehicle speed sensor and the like in addition to the steering angle of the front wheels to a control means consisting of a microcomputer, etc. The hydraulically driven rear wheel steering device is configured to be controlled so that the steering angle is determined according to the caulked table. In this case, there is an advantage that the steering angle of the rear wheels is not uniquely determined according to the steering angle of the front wheels, but can be set according to various situations. By the way, in order to optimize the driving ability at all vehicle speeds, it is necessary to adjust the steering angle of the front wheels at low speeds, where there is little need to consider centrifugal force, and at high speeds, where it is necessary to consider the effects of centrifugal force. It is known that it is preferable that the steering ratio k, which represents the ratio of the steering angle of the rear wheels to the steering angle, changes as shown in FIG. 3 of the present application. Here, a region where the steering ratio k is positive indicates that the rear wheels are steered in the opposite direction to the front wheels, so-called anti-phase, and a region where the steering ratio k is negative indicates that the rear wheels are steered in the same direction as the front wheels. Indicates that the wheels are steered, that is, they are in the same phase. As is clear from the graph in Figure 3, at low speeds, the rear wheels are steered in the opposite direction to the front wheels, resulting in a smaller turning radius of the vehicle body, and conversely, at high speeds, the rear wheels are steered in the same direction as the front wheels. As a result, the turning radius of the vehicle body becomes larger than the steering feel of the steering wheel. Changes in the steering ratio according to vehicle speed are determined so that no slip angle of the vehicle body occurs at low speeds, where the influence of centrifugal force is small, and at high speeds, where the influence of centrifugal force is large. , In this case, the following problems may occur. In other words, if you stop the car with the front wheels turned significantly left and right, such as when parking in a garage or parallel parking, the rear wheels will be turned significantly in the opposite phase to the front wheels, so if you stop the car after a while, When starting the car again, the driver may feel confused due to the movement of the car body that differs from that during normal steering operation. As a conventional example of solving such a problem, for example, as shown in Japanese Patent Application Laid-open No. 56-163969, when the front wheel steering angle is very large, the rear wheel steering angle is returned to 0. There is something like this.

[Problems to be solved by the invention]

However, in the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 56-163969, the condition for returning the rear wheel steering angle to 0 is that the steering angle of the front wheels is above a certain level, so the front wheels are not fixed to the specified tool. - Whenever the steering wheel is turned to H, the steering angle of the rear wheels is 0.
The disadvantage is that you cannot take full advantage of the four-wheel steering when you want to make small turns. Furthermore, when the steering angle of the front wheels exceeds a certain amount, the steering angle of the rear wheels suddenly returns from the opposite phase to O, so there is a concern that the steering stability at low speeds may actually deteriorate. This invention was conceived under the above circumstances,
During a series of rides, the steering angle of the rear wheels can be controlled using a predetermined steering ratio according to the vehicle speed, while the steering angle of the rear wheels automatically returns to 0 when the vehicle starts moving again. The object of the present invention is to provide a four-wheel steering system that can avoid the danger caused by the inability to confirm which direction the rear wheels are facing when starting the vehicle, which occurs in conventional four-wheel steering systems. .

[Means to solve the problem]

In order to solve the above problems, the four-wheel steering system according to the present invention employs the following configuration. i.e. powered via accessory switch, 1iif
A four-wheel steering system that includes a control device that controls a rear wheel steering mechanism according to an optimal steering ratio depending on the steering angle of the wheels and the vehicle speed, the system comprising: an engine operation detector that detects engine rotation; and an ignition switch. an ignition switch OFF detector that detects that the accessory switch has changed from an ON state to an OFF state; a first relay switch that selects an ON state that bypasses the accessory switch and an OFF state that does not bypass the accessory switch by the control device; a second relay switch that selects an ON state that bypasses the relay switch and an OFF state that does not bypass the relay switch, and the control device further turns on the first relay switch and the second relay switch in response to a signal from an engine operation detector. a relay switch ON drive means for activating; a rear wheel reset means for controlling the rear wheel steering mechanism so that the rear wheel steering angle becomes 0 in response to a signal from an ignition switch OFF detector; A relay switch OFF driving means is provided for turning off the first relay switch and the second relay switch.

[Effect]

A starter switch equipped with a normal key cylinder has an accessory switch and an ignition switch that are closed in sequence as the key is rotated, and finally, when the key is rotated to the starter position, the engine starts. When the engine starts, a signal from the motion detector indicating that the engine is in operation is sent to the control device, and in response to this signal, the race iso-starting drive means in the control device turns on the first relay iso-start and the second relay switch. Select. At this time, even if the accessory switch and the ignition switch itself are turned off,
Unless the relay switch OFF driving means selects the first relay switch and the second relay switch to be OFF,
Substantially, accessories including the control device and the rear wheel steering mechanism are in an operable state, and the engine continues to rotate and continues to send hydraulic pressure to the rear wheel steering mechanism. 'In this normal driving condition, the control device determines that the steering ratio, which is the ratio of the steering angle of the rear wheels to the steering angle of the front wheels, which is changed by the steering operation, is a steering ratio set in advance as a function of the vehicle speed. The rear wheel steering mechanism is controlled so that the maximum drivability is achieved at all vehicle speeds. On the other hand, when you stop the car, turn off the engine, and get out of the car,
The device of the present invention operates as follows. That is, usually
At this time, the driver turns the key all at once to turn off the ignition switch and accessory switch. However, since the first relay switch and the second relay switch are turned ON when the engine is started as described above, the control device and the rear wheel steering mechanism are actually still in operation. Then, when the ignition switch is turned off, the rear wheel reset means of the control device controls the rear wheel steering mechanism so that the rear wheel steering angle becomes zero based on a signal from the ignition switch OFF detector that detects this. Then, the steering angle of the rear wheels is returned to 0.
The FF drive means turns off the first relay switch and the second relay switch, and at this time the engine is stopped and the accessory power source is turned off.

【effect】

As described above, in the four-wheel steering system of the present invention, the turning angle of the rear wheels is automatically adjusted in conjunction with the OFF operation of the ignition switch, which is an expression of the driver's intention to stop the car and move away from the car. is set back to 0, so when you get back in the car and start the car, the rear wheels are always pointing straight in the front and rear direction, and you can start off safely with the same feeling as a normal car without a rear wheel steering device. can be done.

[Explanation of Examples]

Embodiments of the four-wheel steering system of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic diagram of the overall configuration of an example of a four-wheel steering system according to the present invention. Here, a conventionally known front wheel steering mechanism 1 is used. That is, in the case of a rank-binion type steering mechanism, the rotation of the steering shaft 3 that rotates together with the steering wheel 2 is converted by the gear box 4 into reciprocating motion of a rack rod 5 in the vehicle width direction, and further The reciprocating motion of the knuckle arm 7.5 is converted into a rotation about the axis 8.8 of the knuckle arm 7.7 via the tie rods 6.6 at both ends, and this rotation of the knuckle arm causes the front wheels 9,
9 is adapted to be steered around the axes 8, 8. On the other hand, the rear wheel steering mechanism 10 in this example includes a stepping motor 12 controlled by a control device 1) composed of a microcomputer, etc.
Known power steering device 1 to which rotation of 2 is input
3. The power steering device 13 in this example is of the so-called rank-binion type, and its input section 14 is linked to the stepping motor 12, and the power cylinder 15 is driven in accordance with the rotational direction of the output shaft of the stepping motor 12. A rack rod 16 extending in the width direction is reciprocated. Movement of the rack rod 16 is controlled by tie rods 17 connected to both ends of the rack rod 16.
．． 17 to the knuckle arm 18.18, causing this knuckle arm 18,1B to rotate about an axis 19.19, thus causing this knuckle arm 18,1
The rear wheels 34, 34 attached to the shafts 19, 19
The ship is steered around the center. FIG. 2 shows details of the linkage structure between the stepping motor 12 and the power steering device 13. In this example, the rotation of the output shaft 20 of the stepping motor 12 is decelerated and input to the input section 14 of the power steering device 13. That is, the output shaft 2 is installed in the gear housing 21 attached to the stepping motor 12.
The small gear 22 attached to the transmission shaft 23 and the large gear 24 which is attached to the transmission shaft 23 and meshes with the small gear 22 are assembled, and the transmission shaft 23 and the input shaft 2 of the power steering device are connected.
5 and shaft 2 connected at both ends with a universal joint.
Connected by 6. The input shaft 25 of the power steering device 13 passes through a control pulp section 27 and has a pinion 28 formed at its tip, which meshes with a rack rod 16 that is slidable from side to side within a gear box 29. The part designated by the reference numeral 30 on the left side of the gear box 29 is a power cylinder part, which includes a piston 3 fixed to the rack rod 16.
1, and a pair of hydraulic boats 32 and 33 connected to a control valve are provided so that the piston 31 can be driven in both directions. This rank-binion type power steering device 13 boosts the power of the stepping motor 12.
The rack rod 16 is moved in a direction according to the direction of rotation, and the rear wheels 34.degree. 34 are steered by a predetermined angle in a predetermined direction. On the other hand, a control device 10 composed of a microcomputer
As shown in FIG. 1, inputs for controlling the rear wheel steering mechanism 10 include a front wheel steering angle signal from a front wheel steering angle sensor 35, a vehicle speed signal from a vehicle speed sensor 36, and a rear wheel steering angle sensor 37. , and a control line 38 to the stepping motor 12 extends thereto. As the front wheel steering angle sensor 35, for example, a disc with a slit is fixed to the steering shaft, and a light emitting element and a light receiving element are arranged to sandwich this disc, and when the disc rotates, the disc with a slit is fixed to the steering shaft. A known device configured to count the number of times a plate blocks the light emitted by the light emitting device can be used. Furthermore, a similar sensor can be used for the rear wheel steering angle sensor 37. As the vehicle speed sensor 36, for example, a known sensor used for inputting information to an electrically driven speedometer can be used. On the other hand, the zero reset control function of the rear wheel turning angle, which is the main point of the present invention, is achieved as follows. That is, first,
Accessory power line 40 extending from battery 39
A first relay switch 42 is attached in parallel to the accessory switch 41 which is installed in the accessory switch 41 and is capable of selecting an ON state in which the accessory switch 41 is bypassed and an OFF state in which the accessory switch 41 is not bypassed. The first relay switch 42 is controlled to be turned on and off by the control device 1). Note that this control device 1) obtains electric power from this accessory power line. Further, an ignition switch 44 interposed in the starter power line 43 extending from the battery 39 has a second switch that selects an ON state in which the ignition switch 44 is bypassed and an OFF state in which the ignition switch 44 is not bypassed. A relay switch 45 is attached in parallel, and this second relay switch 45 is also controlled to be turned on and off by the control device 1). The engine operation signal from the engine operation detector 46 and the ignition switch O attached to the ignition switch 44 are used as inputs for rear wheel steering angle 0 reset control.
An ignition switch OFF signal from the FF detector 47 is input. The engine operation detector 46 can be easily constructed by, for example, detecting that the voltage value obtained by converting the frequency of the ignition pulse exceeds a predetermined comparison voltage, as shown in detail in FIG. can do. Furthermore, the ignition switch OFF detector 47 can be easily constructed by detecting changes in the current of the starter power line. Next, the operation of the rear wheel steering system of this example will be explained based on the flowchart of FIG. When the driver inserts the key into the key cylinder, turns the key to close the accessory switch 41 and the ignition switch 44 in sequence, and turns the key to the start position to start the engine (SIOI>, control device 1), the first relay switch 42 and the second relay switch 45 are turned on (S102°S103). As a result, even if the driver turns off the ignition switch 44 and the accessory switch 41, the accessory power line 40 and the starter power-in are turned off.
The state is such that it is not FF. After that, unless the ignition switch 44 is turned off, the control device 1)
, normal four-wheel steering control is performed (S104). In normal four-wheel steering control, in response to vehicle speed information from the vehicle speed sensor 36 (5201), a data table as shown in FIG. Read out the steering ratio k 520
3) A target rear wheel steering angle is calculated based on this steering ratio and front wheel steering angle information from the front wheel steering angle sensor 35 (S204).
. Then, the rear wheel steering mechanism IO is controlled to steer the rear wheels 34 in a predetermined direction at a predetermined angle so that the feedback signal from the rear wheel steering angle sensor 37 becomes equal to this target rear wheel turning angle. On the other hand, when the car is stopped and the key is turned to turn off the ignition switch 44 and accessory switch 41 (3105), the control device 1) controls the rear wheel steering mechanism 10 to return the steering angle of the rear wheels 34 to 0. control. In this case as well, specifically, the information from the rear wheel steering angle sensor 37 determines which direction the rear wheels should be steered, and until the feedback information from the rear wheel steering angle sensor 37 reaches O. The rear wheels will be steered (S106). rear wheel 34
When the steering angle returns to 0, the first relay switch 42 and the second relay switch 45 are selected to be OFF (310
7, 3108), only then are the accessory power line and the starter power line turned OFF. As explained above, in the four-wheel steering system of the present invention, when the engine is turned off and the vehicle is stopped, the steering angle of the rear wheels is always returned to 0. This eliminates the discomfort caused by the rear wheels being steered significantly when starting the car again, allowing the car to start safely at all times.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the four-wheel steering system of the present invention, FIG. 2 is a detailed diagram of the four-wheel steering mechanism, and FIG. 3 is an example of a data table showing the optimum steering ratio depending on vehicle speed. Graph, 4th
The figure is a detailed diagram of the rear wheel steering angle 0 reset control circuit, Figure 5 f.
al, (bl are flowcharts showing control procedures in the present invention.

Claims (1)

[Claims] (1) A four-wheel steering system that is supplied with electric power via an accessory switch and includes a control device that controls a rear wheel steering mechanism according to an optimal steering ratio according to the steering angle of the front wheels and the vehicle speed, the engine an ignition switch OFF detector that detects when the ignition switch changes from an ON state to an OFF state; and an ignition switch OFF detector that detects when the ignition switch changes from an ON state to an OFF state; a first relay switch that is selected, and a second relay switch that is selected by the control device to have an ON state in which the ignition switch is bypassed and an OFF state in which the ignition switch is not bypassed; Then turn on the first relay switch and the second relay switch.
a relay switch ON drive means for activating; a rear wheel reset means for controlling the rear wheel steering mechanism so that the rear wheel steering angle becomes 0 in response to a signal from an ignition switch OFF detector; A four-wheel steering device comprising: a relay switch OFF drive means for turning off a first relay switch and a second relay switch.