JPS6118570A - Four wheel steering unit for car - Google Patents

Abstract

PURPOSE:To prevent bending of coupling shaft upon collision by splitting the coupling shaft while preventing relative rotation through coupling section. CONSTITUTION:The rear shaft 19 is splitted into first and second shafts 25, 26 on same line where the front end section of second shaft 26 is inserted slidably into an insertion hole 25a while a small diameter section 26a having approximately rectangular cross-section is formed at the front end section. The portion surrounded by the small diameter section 26a and the innercircumferential face at the rear end section of first shaft 25 is the coupling chamber 28 where resin 29 is filled in the engaging holes 25b. In such a manner, a coupling section 27 for blocking the relative motion in the axial and rotary directions of said shafts 25, 26 while slides axially for the axial load higher than predetermined level is formed at the facing section of said shafts 25, 26.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a four-wheel steering system of a vehicle, in particular, to transmit steering power from a front wheel steering system to a rear wheel steering system via a connecting shaft. This invention relates to a four-wheel steering device.

[Prior art]

Generally, a four-wheel steering system for a vehicle is used to steer both the front wheels and the rear wheels by steering the front wheels, thereby enabling turning with a small turning radius or stable cornering at high speeds.

In such a four-wheel steering device, there are various structures for transmitting the steering power from the front wheel steering device to the rear wheel steering device. As described in the publication, there was a system in which a front wheel steering mechanism and a rear wheel steering mechanism were connected by a connecting shaft.

By the way, in a vehicle having the above-mentioned conventional connection shaft, when the rear wheel steering mechanism is pushed forward in the event of a collision such as a rear-end collision, the connection shaft bends in a dogleg shape. If this deformation occurs, there is a risk that a fuel tank provided near the shaft or a portion of the vehicle body near the shaft may be damaged.

[Purpose of the invention]

The present invention was made in such a conventional situation,
It is an object of the present invention to provide a four-wheel steering system for a vehicle that can prevent deformation of a connecting shaft even in a collision such as a rear-end collision, thereby preventing damage to a fuel tank or a vehicle body due to the deformation.

[Structure of the invention]

The present invention provides a four-wheel steering system for a vehicle in which a first... The shaft is divided into a second shift shaft, and the joint that connects both shafts is configured so that both shafts do not rotate relative to each other, and can be moved relative to each other in the axial direction in response to an axial load exceeding a set value. This prevents the first and second shafts from moving relative to each other in the axial direction and bending the connecting shaft in the event of a collision.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 4 show a first embodiment of the present invention. In the figures, 1 is a four-wheel steering system for an automobile, and the system 1 is a front-wheel steering system 2. Rear wheel steering device 3 and both devices 2
, 3 are connected to each other by a connecting shaft 4.

Steering shaft 5 of the front wheel steering device 2
A front wheel steering binion case 6 is provided below, the case 6 is fixed to a rack case 7, and the rank case 7
is fixed to the floor 8 by a bracket 8a. The pinion 6a connected to the steering shaft 5 meshes with a rank par 7a slidably provided in the luff case, and the right (upper side in FIG. 3) end of the rank par 7a is connected to the right quirod 9a. Furthermore, the left (lower side in FIG. 3) end of the rack bar 7a is connected to a left tie rod 9b, and each tie rod 9a, 9b is connected to a front wheel 10, respectively. Note that 11 is an A-type arm that swingably supports the front wheel 10.

A rack case 13 for taking out rear wheel steering is disposed above the front wheel steering rack case 7, and the case 1
The upper part of the connecting bracket 12 is connected to the left end of the rank par 132 that is slidably inserted into the connecting bracket 132, and the lower part of the connecting bracket 12 is fixed to the base of the left tie rod 9b.

Also, the rear wheel steering rack case 14 of the rear wheel steering device 3
is attached to the cross member 15, and the rack case 1
A power cylinder 18 is formed on the right side of 4. Note that 18a is a hydraulic pressure supply pipe, and 18b is a control valve. Further, both ends of the rack bar 142 slidably inserted into the rack case 14 and the rear end 17 are connected by a tie rod 16, and the rear end 17 is rotatably moved from side to side by the cross member 15. It is supported so that it can swing freely.

The connecting shaft 4 includes a front shaft 18 and a rear shaft 19 connected to the front shaft 18 by a universal joint 24, and is disposed below the floor 8. The rear end of the front shaft 18 is rotatably and axially movably supported by a bearing 31, and the front end of the front shaft 18 is connected to a pinion shaft 20 by a universal joint 21, - the pinion A pinion gear (not shown) formed at the tip of the shaft 20 meshes with the rear wheel steering/output rank par 132.

The rear end of the rear shaft 19 is connected to a pinion shaft 22 by a universal joint 23, and a pinion gear (not shown) is formed at the rear end of the pinion shaft 22.
is meshed with the rear wheel steering rack bar 148.

The rear shaft 19 is divided into a first shaft 25 and a second shaft 26 on the same straight line, and the rear end of the first shaft 25 has an inner diameter that is approximately the same as the outer diameter of the other parts. A hole 2.5a is formed, and a number of engagement holes 25b communicating with the insertion hole 25a are bored. Further, a front end portion of a second shaft 26 is slidably inserted into the insertion hole 25a, and a small diameter portion 26a having a substantially rectangular cross section is formed in the front end portion. The portion surrounded by the inner peripheral surface of the rear end of the 1 shaft 25 is a coupling chamber 28, and the coupling chamber 28 and the engagement hole 2
Resin 29 is filled inside 5b. In this way, the above 1. A coupling portion 27 is provided at the opposing portion of the second shaft 25, 26 to prevent relative movement of both shafts 25, 26 in the axial and rotational directions, and to slide in the axial direction in response to an axial load exceeding a predetermined value. is formed.

Further, a fuel tank 30 is disposed between the first shaft 25 and the floor 8. Note that 32 is a rear seat, 33 is a front seat, and 34 is a change lever.

Next, the operation will be explained.

In this embodiment, during normal operation, the first shaft) 2
5.26 is connected mainly to the engaging hole 25b portion of the resin 29 of the connecting portion 27 so as not to move relative to each other in the axial direction and rotational direction. Therefore, during normal operation, the connecting shaft 4 of this embodiment It operates in exactly the same way as the connecting shaft of a conventional four-wheel steering system, and can steer the rear wheels 17 in accordance with the steering of the front wheels 10.

For example, when a large external force is applied to the rear wheel steering device 3 due to a rear-end collision and the device 3 moves forward, the conventional device has a problem in that the connecting shaft bends;
However, in this embodiment, the engagement hole 2 of the resin 29 of the joint portion 27
5b is sheared, and this causes the second shaft 26 to slide axially forward within the insertion hole 25a of the first shaft 25 to absorb the movement of the rear wheel steering device 3, so that the connecting shaft 4 It never bends.

For example, even if the front wheel steering device 2 moves rearward due to a large load from the front of the vehicle, the engaging hole 25b portion of the resin 29 of the joint portion 27 will be is sheared, and the first shaft 2 moves axially rearward to absorb the movement of the front wheel steering device 2, so that the connecting shaft 4 is not bent.

In this embodiment, the second shaft 26 is slidably inserted into the first shaft 25, and both shafts 25, 26
is fixed with resin 29, so that during normal driving, play is prevented from occurring between the center shafts 25 and 26, and the steering power from the front wheel steering device 2 is transferred to the rear wheel steering device 3. The transmission is reliable, and in the event of a collision, the first shaft 25 and the second shaft 26 are moved relative to each other in the axial direction, and bending of the connecting shaft 4 can be reliably prevented.As a result, the fuel tank 30. Damage to the floor 8 etc. due to deformation of the connecting shaft 4 can be prevented.

In this embodiment, an insertion hole is provided at the rear end of the first shaft so that the second shaft can be inserted into the insertion hole of the first shaft. You may also insert it.

FIG. 5 shows a modification of the coupling portion 27 of the first embodiment.

In the figure, the same reference numerals as in FIG. 3 indicate the same or corresponding parts, and 35 indicates the 1st. The bottle is fixed through the second shaft 25.26, thereby allowing the first and second shafts 25.2
A coupling portion 37 is formed that prevents relative movement of the shaft 6 in the axial direction and rotational direction, and allows relative movement in the axial direction in response to an axial load exceeding a predetermined value.

In this modified example, during normal driving, steering power from the front wheel steering device 2 is transmitted to the rear wheel steering device 3 via the coupling portion 37, similar to the first embodiment. In addition, in this modification, in the event of a collision, the connecting pin 3 is
5 is sheared, which causes the first. Second shaft 25.2
6 moves relative to each other in the axial direction, thereby preventing bending of the connecting shaft 4.

6 and 7 show a second embodiment of the invention.

In the figure, the same reference numerals as in FIG. 4 indicate the same or corresponding parts, and in the second embodiment, the front shaft 18 is located on the same straight line as the first. It is divided into second shafts 45 and 46, and a coupling portion 47 is formed at the opposing portion of both shafts 45 and 46.

The rear end portion 45a of the first shaft 45 is formed into a plate shape with a 7-shaped plane, and the front end portion 46a of the second shaft 46 is formed into a rod shape with a rectangular cross section. The provided connecting bolt 48 is connected to the recess 4 of the rear end portion 45a.
5b, and the connecting bolt 48 connects the first.
The second shaft 45,46 is connected.

In the second embodiment, during normal operation, the operation is the same as in the first embodiment, and in the event of a collision, the rear end portion 45a of the first shaft 45 and the connecting bolt 48 slip due to the axial force, and as a result, the front wheel steering device 2 Alternatively, the bending of the connecting shaft 4 can be prevented by absorbing the movement of the rear rotation device 3.

In addition, in each of the above embodiments, three examples were shown as the structure of the joint part, but it goes without saying that the structure is not limited to these, and the point is that when a large load is applied in the axial direction, 1st. Any structure may be used as long as the second shaft can move relatively in the axial direction. Furthermore, in each of the above embodiments, a case has been described in which the front shaft 18 or the rear shaft 19 is divided into two shaft parts and one connecting part is provided, but it is divided into three or more shaft parts and two or more shaft parts are provided. A coupling portion may be provided, and in this way, the amount of absorption of axial movement can be increased.

〔Effect of the invention〕

As described above, according to the four-wheel steering system for a vehicle according to the present invention, the connecting shafts are arranged on the same straight line at least in the first . It is divided into a second shaft, and the two shafts are connected by a connecting part so that they do not rotate relative to each other, and so that they move relative to each other in the axial direction in response to a large load in the axial direction, so they are connected in the event of a collision. 1 to 4 show a four-wheel steering system on a vehicle according to a first embodiment of the present invention, and FIG. 1 is a partial cross-section of the joint portion thereof. Side view, Figure 2 (, 11 is ■a-II in Figure 1
2(b) is a sectional view taken along line a, FIG. 2(b) is a sectional view taken along line nb-nb of FIG. 1, FIG. 3 is a plan view thereof, FIG. 4 is a side view thereof, and FIG. 5 is a combination of the above first embodiment. 6 and 7 show a second embodiment of the present invention, FIG. 6 is a side view thereof, and FIG. 7(a) is a side view of a joint portion thereof. The plan view and FIG. 7(b) are its side views.

1-Four wheel steering device, 2-Front wheel steering device, 3
-Rear wheel steering device, 4... connected shaft, 25, 45-
First shaft, 25a-insertion hole, 25b-engaging hole, 2
6, 46-second shaft, 26a-small diameter portion, 27. 3
7. 47-Joining portion, 28...Joining chamber, 29-Resin.

Patent applicant: Mazda Motor Corporation Agent: Patent Attorney Ken Hayase - Figure 1 Figure 2

Claims (2)

[Claims] (1) In a four-wheel steering device for a vehicle that transmits steering power from a front wheel steering device to a rear wheel steering device via a connecting shaft and steers the rear wheels in accordance with the steering of the front wheels, the connecting shaft has at least The first shaft and the second shaft are divided into a first shaft and a second shaft, and the first shaft and the second shaft are connected at a connecting portion so that there is no relative movement in the rotational direction on the same straight line, and the connecting portion is set as a connecting shaft. A four-wheel steering system for a vehicle, characterized in that the first shaft and the second shaft are relatively movable in the axial direction when an axial load greater than the load is applied. (2) The coupling part has an insertion hole and an engagement hole communicating with the insertion hole formed at one end of the first shaft or the second shaft, and the other end of the first shaft or the second shaft. A small diameter portion is formed, and the first shaft or the second shaft is inserted into the insertion hole of one of the first shaft and the second shaft.
A small diameter portion formed at the other end of the shaft is inserted, and a coupling chamber is formed by the small diameter portion and the inner peripheral surface of the insertion hole;
The four-wheel steering system for a vehicle according to claim 1, wherein the coupling chamber and the engagement hole are filled with resin.