JPS63301184A - Rear wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To enable a rear wheel driving means to be commonly used for the right and left wheels, and to enable the right and left turning characteristics of a vehicle to be kept always same by providing an interlocking mechanism for mechanically interlocking the right and left rear wheels with each other so as to be simultaneously brought into toe-in. CONSTITUTION:In the same way as a front wheel steering mechanism A, a rear wheel steering mechanism 6 has a pair of right and left knuckle arms 10R, 10L, and the rods 11R, 11L respectively, and further a connecting mechanism D connecting these the rods 11R and 11L is provided. The connecting mechanism D is mechanically interlocked with the right and left rear wheels 2R and 2L so as to be simultaneously brought into toe-in. In other words, when the right side knuckle arm 10R is turned in the counterclockwise direction around the turning center 10R' to bring the right rear wheel 2R into toe-in, the left side knuckle arm 10L is turned in the clockwise direction around the turning center 10L' to bring the left rear wheel 2L into toe-in.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a rear wheel steering system.

(Prior art) Some four-wheel steering vehicles in which both the front wheels and the rear wheels are steered are capable of simultaneously steering the left and right rear wheels in the toe-in direction, as shown in Japanese Patent Application Laid-open No. 6O-193780-). There is something that lets you do it. In other words, a cylinder device is installed between the left and right suspension arms that support the rear wheels and the vehicle body, and these left and right cylinder devices allow the front wheels to be steered within the range of compliance (elastic deformation of the elastic bushing in the suspension). It has been proposed that both the left and right rear wheels have toe-in.

In this way, in a vehicle in which both the left and right rear wheels are toe-in, the inner rear wheel when turning can be toe-in in advance in preparation for the next turn in the opposite direction. As a result, even on driving roads where there are continuous left and right curves, the toe-in of the rear wheels, especially the rear wheels on the outer side during turns, can be controlled with good response. It becomes desirable.

(Problem to be solved by the invention) However, in order to toe-in the left and right rear wheels at the same time,
As described in the above-mentioned publication, providing the drive f-stage (cylinder device in the above-mentioned publication) for steering each independently and exclusively for the left and right rear wheels would be costly or difficult to control. It becomes undesirable if it becomes i-based.

In addition to this, if one of the left or right drive stages breaks down, one rear wheel will not be towed in.
The turning characteristics will be different when turning to the left and turning to the right.

The present invention was made taking into consideration the spring sentiments described in 1-1 below, and is based on the premise that the left and right rear wheels are toe-in at the same time, so that the same turning characteristics can always be obtained when turning left and right. , the means for applying an external force to steer the rear wheels can be shared between the left and right rear wheels.・11
The purpose of the present invention is to provide a rear wheel steering device.

(Means and operations for solving the problem) In order to achieve the above-mentioned object, in the present invention, the left and right rear wheels are mechanically linked to each other by a linkage mechanism so that toe-in occurs at the same time. be.

With this configuration, the left and right rear wheels can be towed in at the same time by connecting one drive means to the linkage mechanism. In addition, the left and right rear wheels are driven by
Even when the 1F stage is always working or when it fails, the steering conditions of the left and right rear wheels are exactly the same, and the left and right turning characteristics can always be set in the same way.

(Embodiments) Examples of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, lR is the right front wheel, IL is the left front wheel, 2R is the right rear wheel, and 2L is the right rear wheel.The left and right front wheels IR1IL are linked by a front wheel steering mechanism A, and the left and right rear wheels 2R1
2L is linked by rear wheel steering mechanism B.

In the embodiment, the front wheel steering mechanism A includes a pair of left and right knuckle arms 3R13R and a tie rod 4R14L, and a relay rod 5 that connects the pair of left and right tie rods 4R54L. A steering mechanism C is linked to the front wheel steering mechanism A, and the steering mechanism C is of a rack-and-binion type in this embodiment. In other words, relay lot 5 has rack 6.
On the other hand, a pinion 7 that fits the rack 6 is connected to the handle 9 via a shaft 8.Thereby, when the handle 9 is turned to the right, the relay rod 5 is displaced to the left in Fig. 1, and the knuckle arm 3R13L moves to the right by an amount corresponding to the steering angle of the steering wheel 9. Similarly,
/\When the steering wheel 9 is operated to the left, the left and right front wheels IR1IL are steered to the left in accordance with this operation displacement j rule.

Similarly to the front wheel steering mechanism A, the rear wheel steering mechanism B also has a pair of left and right knuckle arms l0R110L and tie rods 11R, 11L, and the tie rod 4R54.
It has a connecting mechanism that connects L comrades. As described later, this connection mechanism connects the left and right rear wheels 2R12L at the same time (
(both) are mechanically linked to achieve toe-in. In other words, when the right knuckle arm IOR rotates counterclockwise in FIG. It is rotated clockwise in Figure 1 around the center of motion 10L' (the left rear wheel 2L is
in).

−. The connection mechanism will be described in detail with reference to FIG. The coupling mechanism shown in Fig. 4 is a toothed Φ type, and each! 1 (has a pair of left and right southeast 21R121L rotatably supported on the body. Both teeth Ilj 21
R121L is engaged with Ir: and its co-moving center 21
One end of the first split relay rod 22R or 22L is movably connected to a position eccentric from R' and 21L'. this first minute), 1 relay rod 22
R (22L) is the second minute; I, Il relay rod 23R
(23L), tie rod IIR (I
LL). 2nd split rod 2
3R (23L) is held slidably in the mold width direction with respect to the middle rest, and is also supported by disk-shaped stoppers 24RC241,
) are integrated. And this stopper 24R (
24L) as one spring seat
By R (25L), 2nd minute 11, 1 relay rod 23
R (23L) is biased toward the inner force side in the middle 1 width direction.

Now, when the right tooth "lL21R" is rotated clockwise in FIG. 4, this rotational force is applied to each rod 22R123R,
It is transmitted to the knuckle arm IOR via R, and the right rear wheel 2R is toe-ined. As the tooth width 21H on the right side rotates clockwise in FIG. 4, the gear 21L on the left side rotates counterclockwise in FIG.
It is transmitted to the knuckle arm IOL via 3L and IIL, and the left rear wheel 2L is also towed in. When the rotational force on the gear 21R is released, the rear wheel 2R12L is moved by the stopper 24R1 by the return spring 25R125L.
24L is forcibly returned to the position where it contacts the vehicle body, and this returned position is the position where each rear wheel 2R12L is in the middle ☆: position.

In this way, the stopper 24R124L is a single stage that prevents the left and right rear wheels 2R12L from being steered in the toe-out direction. Also, return spring 25R
The biasing force of 125L forcibly maintains the rear wheel 2R12L in the neutral position against the external force applied to the rear wheel 2R22L during driving when a failure occurs in the drive system that drives the southeast 21R, which will be described later. constitutes a fail-safe measure.

Next, a description will be given of the means for driving the gear 21R, that is, the drive stage E for toeing in the left and right rear wheels 2R12L. This drive stage E consists of a shaft 31 rotatably held on the vehicle body and fixed to the 1st part 21R, a binion 32 fixed to the shaft 31, a rack 33 fitted to the binion 32, and a pole screw. A step motor 35 that drives the rack 33 via a step motor 34 is provided. The above-mentioned pole screw 34 has a center shaft 34a and an outer cylinder 34.
b, and a large number of poles 34c interposed between both 34a and 34b. As is known, such a pole screw 34 has an outer circumference of a center shaft 34a and an outer cylinder 35.
A threaded groove in which the pawl 34c can be moved is formed on the inner periphery of the shaft 34b, and the outer cylinder 34b is reciprocated by rotating the center shaft 34a (which is fixed in the axial direction) forward and backward. Then, the rack 33 is integrated into the outer cylinder 34b,
Further, the step motor 35 rotates the center shaft 34a in forward and reverse directions. Therefore, step motor 3
In accordance with the forward/reverse rotation of Ilj 5, Ilj 21R is also rotated forward/reverse (steering color tone ff1 of rear wheel 2R12L).

Note that the fki east 21R121L is actually set so that its rotation centers 21R' and 21L' are in the Ilj body longitudinal force direction, respectively.

The drive of 11j 21 R by the step motor 35 is hydraulically power assisted by a power cylinder mechanism F. For this reason, a cylinder 41 fixed to the vehicle body is disposed on the outer periphery of the outer cylinder 34b of the pole screw 34, and a piston 42 integrated with the outer periphery of the outer cylinder 34b allows the inside of the cylinder 41 to be divided into two oil chambers 43a and 43b. It is defined as. This oil chamber 43a,
43b is connected to the center shaft 34a via piping 44 or 45.
It is connected to a rotary control valve 46 attached to the rotary control valve 46. The control valve 46 also includes pipes 48 and 49 connected to the reservoir 47, respectively.
A pump 51 driven by a motor 50 is connected to one of the pipes 48 . Incidentally, since the operation of such a power cylinder mechanism F itself is well known, the explanation thereof will be omitted.

Furthermore, in the embodiment, a solenoid valve 52 is provided for communicating the pipes 44 and 45.

61 in FIGS. 1 and 4 is a control unit composed of a microcomputer, which basically includes a CPU, ROM,
, is equipped with RAM. This control unit 1-61 includes
Voltages from sensors 62-64 and battery 15 are input. The sensor 62 detects the operation II of the steering wheel 9, that is, the steering angle of the steering wheel. The sensor 63 detects vehicle speed. The sensor 64 detects the rotational position of the center shaft 34a in the pole screw 34, that is, the rear wheel 2R.
This is to detect the actual turning angle of 12L.

Then, from the control 22) 61, the step motor 35
and is output to the solenoid valve 52.

For example, as shown in FIG. 2, the control 22) 61 calculates the ratio of the steering angle of the rear wheels 2R12L to the front wheels IR1IL (steering ratio) from the sensor 64, as shown in FIG. Feedback control is performed while monitoring the output. In addition, FIG. 3 is a reinterpretation of FIG. 2 based on the relationship between the steering angles of the front wheels and the rear wheels. Of course, these two figures (Figure 3) are
This shows an example of the position of the steering characteristic of the rear wheels 2R22L (vehicle speed responsive type), and various other steering characteristics may be used as appropriate, such as a steering wheel angle responsive type.

In addition, when some abnormality occurs, the control unit 61 opens the power assist by connecting the pipes 44 and 45 with the solenoid valve 52, and forcibly controls the rear wheel 2R12L with the return spring 25R125L. to the neutral position.

5 and 6 respectively show other embodiments of the present invention, and the same components as in the above embodiments are designated by the same reference numerals.
The explanation will be omitted.

In the embodiment shown in FIG. 5, an electric power assist mechanism G is used in place of the hydraulic power assist mechanism F in the previous embodiment. That is, while the shaft 31 is directly driven by the step motor 35,
A torque sensor 71 and an assist motor (coil) 72 are connected to this shaft 31. and,
A control unit 73 for power assist is separately provided, and the assist motor 7 is controlled according to the output from the torque sensor 71.
2 is controlled by a control unit 73.

In the one in Figure 6, the left and right knuckle arms IOR
and the IOL are connected by one relay rod 13 so that both the left and right rear wheels 2R12L are towed in together. That is, left and right knuckle arms l0R1IO
By extending the arm portions 12R and 12L at L, one toward the front and the other toward the rear, the left and right rear wheels 2R12L are both toe-ined by displacement of the relay rod 13 in one direction along the east width force. Note that there is only one relay rod 13.
Since it is only a book, only one toe-out stopper 14 is provided.

Although the embodiments have been described above, the compliance of the elastic bushings incorporated in the suspension may be used to steer the rear wheels.

(Effect of the invention) As is clear from the above description, the present invention has been made.

In order to toe-in the left and right rear wheels at the same time, this drive means can be shared between the left and right wheels without providing separate drive means for steering the left and right rear wheels.

In addition, since the left and right rear wheels are mechanically linked so that they are toe-in at the same time, even if the drive means or its control means fails, the steering condition ig of the left and right rear wheels can be changed to 7j. Second, it is possible to always maintain the same left and right turning characteristics.

4 Brief explanation of drawings FIG. 1 is an overall system diagram showing one embodiment of the present invention.

FIG. 2 and FIG. 3 are diagrams showing an example of the steering characteristics of the rear wheels.

FIG. 4 is a detailed system diagram showing the main parts of FIG. 1.

FIG. 5 is a system diagram corresponding to FIG. 4, showing another embodiment of the present invention.

FIG. 6 is a system diagram in yellow showing still another embodiment of the present invention.

B: Rear wheel steering mechanism or two connection mechanism E: Drive means 2R12L: Rear wheel 10R1IOL: Knuckle arm 11R, IIL + tie rod 21R121L: @Car 22R122L: First split sea rod 23R123L
:Second split rail end 31:Shaft 32:Binion 33Neck 34:Pole screw 35Step motor

Claims (1)

[Claims] (1) The left and right rear wheels are each supported by the vehicle body so that they can be steered at least in the toe-in direction, and the left and right rear wheels are mechanically linked to each other by a linkage mechanism so that they are simultaneously in toe-in. Features: Rear wheel steering system for vehicles.