JPH03125671A - Four-wheel steering device of vehicle - Google Patents

Abstract

PURPOSE:To precisely control a rear wheel steering device according to vehicle running state by providing two input shafts connected to each other by a continuously variable transmission in an operation control device for controlling the operation of the rear wheel steering device interlockingly with a front wheel steering device, and controlling the gear change ratio. CONSTITUTION:In an operation control device 5 for controlling the operation of a rear wheel steering device interlockingly with a front wheel steering device, a differential gear device 15 is provided, and longitudinally extending input shaft 17 and output shaft 19 are fixed, to the first and second side gears 16, 18, respectively. A first spur gear 23 is fixed to the rear of the input shaft 17, and engaged with a second spur gear 26 on an intermediate shaft 24 pivotally supported on the vehicle body side in parallel to the input shaft 17. The rotation of the intermediate shaft 24 is transmitted to a second input shaft 25 through a belt type continuously variable transmission 29, and a bevel gear 28 fixed to the input shaft 25 is engaged with a ring gear 27 integrated with the gear housing 34 of the differential gear device 15. The gear change ratio of the continuously variable transmission 29 is controlled by a control device 31 according to vehicle speed and a front wheel steering angle.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is a four-wheel steering system for a vehicle, more specifically, it is capable of steering the rear wheels following the steering of the front wheels, and furthermore, it is possible to steer the rear wheels by following the steering of the front wheels. The present invention relates to a steering device that can appropriately adjust the ratio to the angle.

In this specification, the left side of Figure 2 is the front, the right side of the figure is the rear,
The lower side of the figure is referred to as the left, and the upper side of the figure is referred to as the right.

BACKGROUND ART Conventionally, a four-wheel steering device for a vehicle includes a front wheel steering device, a rear wheel steering device, and an operation control device that controls the operation of the rear wheel steering device in conjunction with the front wheel steering device. The operation control device includes a differential gear device, a bevel gear that is fixedly provided on the steering shaft and meshes with a ring gear of the differential gear device, and one end of which is fixed to a first side gear of the differential gear device. an input shaft having the other end connected to the motor; and an output shaft having one end fixed to the second side gear of the differential gear device and the other end connected to the rear wheel steering device.
A motor control device that controls the rotation of a motor according to the vehicle speed and the steering angle of the front wheels is known (see JP-A-59-81272 and JP-A-64-41472).
.

In the four-wheel steering system described above, the operation of the rear wheels is controlled by changing the rotational speed of the input shaft using a motor.

However, in the conventional four-wheel steering device, power is constantly consumed to drive the motor during steering, so there is a problem in that a large power capacity is required. Furthermore, if the output of the battery decreases, there is a possibility that either anti-phase steering or in-phase steering cannot be performed.

An object of the present invention is to provide a four-wheel steering system for a vehicle that solves the above problems.

Means for Solving the Problems A four-wheel steering system for a vehicle according to the present invention includes a front-wheel steering system, a rear-wheel steering system, and an operation control system that controls the operation of the rear-wheel steering system in conjunction with the front-wheel steering system. The actuation control device includes a differential gear, a first input shaft arranged to rotate about an axis, and one end of which is fixed to a first side gear of the differential gear, and an axis. a second input shaft arranged to be rotatable about the axis and provided with a gear that meshes with a gear fixedly provided on the housing of the differential gear; an output shaft having one end fixed to the second side gear of the differential gear device and the other end connected to the rear wheel steering device to operate the rear wheel steering device by rotation around an axis; It consists of a continuously variable transmission that connects the input shaft and the second input shaft, and a gear ratio control device that controls the gear ratio of the continuously variable transmission according to the vehicle speed and the steering angle of the front wheels. Either one of the two input shafts is connected to the front wheel steering device and rotates around the axis when the front wheels are steered.

Another four-wheel steering device for a vehicle according to the present invention includes a front wheel steering device, a rear wheel steering device, and an operation control device that controls the operation of the rear wheel steering device in conjunction with the front wheel steering device. A control device includes a differential gear device, a first input shaft arranged to be rotatable about an axis, and having one end fixed to a first side gear of the differential gear device; a second input shaft that is arranged so as to be parallel to each other and is fixed to a second side gear of the differential gear device; one end portion is connected to the housing of the differential gear device, and the other end portion is connected to the rear wheel steering device. an output shaft that rotates around an axis due to the rotation of the housing and operates the rear wheel steering device; a continuously variable transmission that connects the first input shaft and the second input shaft; and a gear ratio control device that controls the gear ratio of the continuously variable transmission, and one of the first input shaft and the second input shaft is connected to the front wheel steering device and rotates around the axis when the front wheels are steered. This is what it is designed to do.

Operation When one of the input shafts connected to the front wheel steering device is rotated around its axis during front wheel steering, the rotation of this input shaft is transmitted to the other input shaft via the continuously variable transmission, and this input shaft is rotated around its axis. The axis can also be rotated. As a result, the output shaft rotates. At this time, the gear ratio control device controls the gear ratio of the continuously variable transmission according to the vehicle speed and the steering angle of the front wheels, and by variously changing the ratio of the rotation speeds of both input shafts, in-phase steering, anti-phase steering, The operation of the rear wheel steering device can be controlled to provide steering or two front wheel steering. Therefore, by using only the rotation of one of the input shafts that rotates around the axis during front wheel steering, the rear wheel steering device can be operated and controlled to perform in-phase steering, anti-phase steering, or two-wheel front wheel steering. .

Example Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a schematic configuration of a vehicle equipped with a four-wheel steering system according to the present invention. In FIG. 2, the four-wheel steering device includes a front wheel steering device (2) that steers the front wheels (1) of the vehicle, and a rear wheel (3) that steers the front wheels (1) of the vehicle.
a rear wheel steering device (4) that steers the vehicle, and a front wheel steering device (2) that steers the
and an operation control device (5) that controls the operation of the rear wheel steering device (4) in conjunction with the rear wheel steering device (4). The front wheel steering device (2) is of a rack and pinion type, and both ends of a rack rod (6) are connected to the knuckle arm (7) of the front wheel (1) via a tie rod (8). By rotating the steering wheel (9), the rack rod (6) moves in the left-right direction, and the front wheels (1) are steered. The rear wheel steering device (4) includes a rack rod (11) that extends left and right and moves in the axial direction.

Both ends of the rack rod (11) are connected to the knuckle arm (12) of the rear wheel (3) via a tie rod (13). Then, by moving the rack rod (11) in the left-right direction, the rear wheels (3) are steered.

The front wheel steering device (2) and the rear wheel steering device (4) are connected via a connecting shaft (14) that extends back and forth and can rotate around an axis and an operation control device (5). A binion (10) is fixed to the front end of the connecting shaft (14), and this binion (10) meshes with the rack rod (6) of the front wheel steering device (2). Then, the connecting shaft (14) rotates by an amount corresponding to the amount of movement of the rack rod (6) in the left-right direction.

Fig. 1 shows details of the operation control device (5). In Fig. 1, the operation control device (5) is arranged so as to be able to rotate around an axis extending back and forth with the differential gear device (15). and a first input shaft (1γ) whose rear end is fixed to the first side gear (16) of the differential gear device (15), and arranged so as to be able to rotate around an axis extending back and forth, and The front end of the output shaft (19) is fixed to the second side gear (18) of the differential gear (15).The front end of the first input shaft (17) is connected to the universal joint (20). The first input shaft (17) is connected to the rear end of the connecting shaft (14) through the rear end of the output shaft (19), so that the first input shaft (17) rotates together with the connecting shaft (14). A binion (22) that meshes with the rack rod (11) of the steering device (4) is fixedly provided.A first spur gear (
23) is provided in a fixed manner. First input shaft (17)
An intermediate shaft (24) and a second input shaft (25) are arranged so as to be rotatable about their respective axes, and are rotatably supported by the vehicle body. A second spur gear (2B) that meshes with the first spur gear (23) is fixedly provided on the intermediate shaft (24). A bevel gear (28) is fixedly provided at the rear end of the second input shaft (25) and meshes with a ring gear (27) fixedly provided on the gear housing (34) of the differential gear device (15). It is being The rotation of the intermediate shaft (24) is transmitted to the second input shaft (25) by a belt type continuously variable transmission (29).

The gear ratio of the continuously variable transmission (29) is based on the vehicle speed and the front wheels (1
) is controlled by a gear ratio control device (31). The gear ratio control device (31) operates the continuously variable transmission (29) based on output signals from a vehicle speed sensor (32) that detects the vehicle body and a steering angle sensor (33) that detects the steering angle of the front wheels (1). ) changes the gear ratio.

In the differential gear device (15), the first input shaft (17)
If the rotation speed of the ring gear (27), that is, the gear housing (34) is Nb, then the output shaft (1
It is well known that the rotational speed Nc in 9) is expressed by the following equation.

Nc-2Nb-Na Therefore, the rotation speed (Na) of the first input shaft (17) and the rotation speed (Nb) of the ring gear (27) satisfy Nb<1/2.
When the relationship of Na...■ is satisfied, the output shaft (19) rotates in the opposite direction to the first input shaft (17), and N b > 1/2 Na ---------
When the relationship (1) is satisfied, the output shaft (19) is connected to the first input shaft (
17) and rotates in the same direction as N b = 1/2 Na --------
When the relationship (2) is satisfied, the output shaft (19) will not rotate. Therefore, the gear ratio control device (31) changes the gear ratio of the continuously variable transmission (29) and the second input shaft (25)
), and by changing the rotation speed of the ring gear (27), it becomes possible to drive and stop the output shaft (19) and change the rotation direction.

If you turn the steering wheel (9) to the left and move the rack rod (8) of the front wheel steering device (2) to the right, the front wheels (
1) is steered to the left. Then, due to the engagement between the rack rod (6) and the binion (10), the connecting shaft (14) and the first input shaft (17) move clockwise when viewed from the front (the direction indicated by arrow (8) in Fig. 1). ). Further, the intermediate shaft (24) and the second input shaft (25) are respectively oriented counterclockwise when viewed from the front (direction shown by arrow (B) in FIG. 1).
Rotate to.

As a result, the ring gear (27) of the differential gear (15)
The gear housing (34) rotates clockwise when viewed from the front.

Now, as shown in diagram T43, if the vehicle speed detected by the vehicle speed sensor (32) is smaller than the set value (X), the rotation speed (Na) of the first input shaft (17) and the ring gear (27)
The gear ratio of the continuously variable transmission (29) is changed so that the rotational speed (Nb) of the motor satisfies the relationship of the above equation 0. Then, the output shaft (19) rotates counterclockwise (in the direction shown by arrow (C) in Fig. 1) when viewed from the front, and the rack rod (11) engages with the binion (22), causing the rack rod ( 11) moves to the left. As a result, the rear wheels (3) are steered in opposite phase to the front wheels (1), that is, to the right. At this time, the first
Rotation speed (Na) of input shaft (17) and ring gear (27)
The larger the difference from twice the rotational speed (2X Nb), the larger the steering angle.

When the vehicle speed detected by the vehicle speed sensor (32) reaches the set value (X), the number of rotations (Na) of the first input shaft (17) and the number of rotations (Nb) of the ring gear (27) are calculated according to the above formula (■). The gear ratio of the continuously variable transmission (29) is changed so that the relationship is satisfied. In this case, the output shaft (19) does not rotate and the rear wheel (
3) is not steered.

If the vehicle speed detected by the vehicle speed sensor (32) exceeds the set value (X), the rotation speed (Na) of the first input shaft (17) and the rotation speed (Nb) of the ring gear (27) will be The gear ratio of the continuously variable transmission (29) is changed so that the relationship is satisfied. Then, the output shaft (19) rotates clockwise (in the direction shown by arrow (D) in Fig. 1) when viewed from the front, and due to the engagement between the binion (22) and the rack rod (11),
The rack rod (11) moves to the right. As a result, the rear wheels (
3) is in the same phase as the front wheel (1), that is, it is steered to the left. At this time, the larger the difference between the rotation speed (Na) of the first input shaft (17) and twice the rotation speed (2X Nb) of the ring gear (27), the larger the steering angle becomes.

Note that when the front wheels (1) are steered to the right, the operation of the rear wheel steering device (4) is controlled in an operation opposite to that described above.

In the above embodiment, the first input shaft (17) is connected to the front wheel steering device (2), but instead of this, the second input shaft (25) is connected to the front wheel steering device (2). You can stay there. Further, in the above embodiment, the first input shaft (17)
A first flat float (23) is provided in a fixed manner, and the intermediate shaft (24) rotates around its axis so as to be parallel to the first input shaft (17) and the second input shaft (25). The intermediate shaft (24) is arranged like a vine and rotatably supported on the vehicle body.
The second spur gear (21i) meshes with the first spur gear (23).
are provided in a fixed manner, but these are not necessarily necessary, and the first input shaft (17) and the second input shaft (25) may be directly connected by a continuously variable transmission (29). . Furthermore, in the above embodiment, when the output shaft (19) rotates in the opposite direction to the first input shaft (17), the rear wheels (3) are steered in opposite phase to the front wheels (1) and rotated in the same direction. In this case, both wheels (1) and (3) are steered in the same phase, but on the contrary, the output shaft (19) is steered in the same phase as the first input shaft (17).
), both wheels (1) and (3) may be steered in the same phase when the wheels rotate in the opposite direction, and when the wheels rotate in the same direction, the wheels (1) and (3) may be steered in opposite phases.

FIG. 4 shows an operation control device (4) in another embodiment of the present invention.
0) details are shown below. In FIG. 4, the same components as those shown in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted. In FIG. 4, the actuation control device (40) is arranged so as to rotate around an axis extending back and forth, and its front end is fixed to the second side gear (18>) of the differential gear (15). A second input shaft 41) is provided. Second input shaft (41
) is fixedly provided with a bevel gear (42) at the rear end thereof.

The intermediate shaft (43) is parallel to the first input shaft (17).
) is arranged so as to be able to rotate around an axis and is rotatably supported by the vehicle body. A bevel gear (44) that meshes with the bevel gear (42) of the second input shaft (41) is fixedly provided at the rear end of the intermediate shaft (43).

A continuously variable transmission (29) is provided between the first input shaft (17) and the intermediate shaft (43). In addition, at the front end of the gear housing (34) of the differential gear device (15>),
An output shaft (45) is provided in a fixed manner. Output shaft (4
5) is a rear wheel steering device (4) via a transmission device (not shown).
) is connected to.

In such a configuration, similarly to the embodiment described above, by changing the ratio of the rotational speeds of the first input shaft (17) and the second input shaft (41>) using the continuously variable transmission (29), The rotation direction and rotation speed of the output shaft (45) can be controlled. Therefore, the operation of the rear wheel steering device (4) can be controlled to provide in-phase steering, anti-phase steering, or two-wheel front wheel steering.

Effects of the Invention According to the four-wheel steering system for a vehicle of the present invention, as described above, by controlling the gear ratio of the continuously variable transmission that connects the first input shaft and the second input shaft, Utilizing the rotation of the input shaft that occurs, the front and rear wheels are steered in the same phase.
The operation of the rear wheel steering device can be controlled to provide reverse phase steering or two front wheel steering. Therefore, compared to conventional devices that control the rotation speed of the input shaft using a motor,
The power capacity used is reduced, and in-phase steering, anti-phase steering, and two-wheel front wheel steering are always performed reliably.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, in which a horizontal sectional view of an operation control device for a four-wheel steering device, FIG. 2 is a schematic configuration diagram of a vehicle equipped with the four-wheel steering device of the present invention, and FIG. 3 shows a front wheel steering device. and a graph showing the relationship between the steering angle ratio of the rear wheels and the rotation angle of the input shaft. FIG. 4 is a diagram corresponding to FIG. 1 showing another embodiment of the present invention. (2)...Front wheel steering device, (4)...Rear wheel steering device, (5) (40)...Operation control device, (15)...
・Differential gear device, (1G)...first side gear, (1
7)...First input shaft, (18)...Second side gear, (19) (45)...Output shaft, (25) (41)
...Second input shaft, (27) ...Ring gear, (28
)...Bevel gear, (29)...Continuously variable transmission, (31)
...speed ratio control device. that's all

Claims (1)

[Claims] 1. A front wheel steering device, a rear wheel steering device, and an operation control device that controls the operation of the rear wheel steering device in conjunction with the front wheel steering device, and the operation control device has a differential control device. a first input shaft arranged so as to be rotatable around the axis and having one end fixed to a first side gear of the differential gear set; , and a second input shaft provided with a gear that meshes with a gear fixedly provided on the housing of the differential gear device; The first input shaft and the second input shaft are connected to an output shaft that is fixed to the second side gear of the output shaft and whose other end is connected to the rear wheel steering device to operate the rear wheel steering device by rotation around the axis. and a gear ratio control device that controls the gear ratio of the continuously variable transmission according to the vehicle speed and the steering angle of the front wheels, and one of the first input shaft and the second input shaft is A four-wheel steering device for a vehicle that is connected to a front wheel steering device and rotates around an axis when the front wheels are steered. 2. It is equipped with a front wheel steering device, a rear wheel steering device, and an operation control device that controls the operation of the rear wheel steering device in conjunction with the front wheel steering device, and the operation control device includes a differential gear device and an axis line a first input shaft arranged to be rotatable about an axis and having one end fixed to a first side gear of the differential gear; a first input shaft arranged to be rotatable about an axis and having one end fixed to a first side gear of the differential gear; A second input shaft is fixed to the second side gear of the second input shaft, one end is connected to the housing of the differential gear device, the other end is connected to the rear wheel steering device, and the second input shaft is rotated around the axis by rotation of the housing. an output shaft that operates a rear wheel steering device; a continuously variable transmission that connects the first input shaft and the second input shaft; and a continuously variable transmission that controls the gear ratio of the continuously variable transmission according to the vehicle speed and the steering angle of the front wheels. A four-wheel steering system for a vehicle comprising a gear ratio control device, and one of a first input shaft and a second input shaft is connected to a front wheel steering device so as to rotate around an axis when the front wheels are steered. Device.