JPH06227404A - Steering shaft of vehicle - Google Patents

Abstract

PURPOSE:To enable coexistence of prevention of falling deformation of a main shaft due to low setting of collapse load and improvement in shock absorbing performance by securing large deformation stroke of a countershaft in a steering shaft of a vehicle. CONSTITUTION:A countershaft 3 is formed by plural slidable shaft members 31, 32. The shaft members are connected to each other in such a manner as to be broken by a shear pin member 40, and at least one of plural shaft members 31, 32 is provided with fragile parts 33, 34 and with slide regulating members 30, 35 for regulating the slide displacement of the plural shaft members 31, 32 in a designated stroke position. The shear pin member 40 is broken by comparatively small collapse load, whereby it is possible to prevent deformation in the falling direction of the main shaft. Since the countershaft 3 is bent at the fragile parts 33, 34, the deformation stroke at the time of collapse can be enlarged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering shaft of a vehicle which absorbs a shock at the time of a vehicle collision.

[0002]

2. Description of the Related Art A steering shaft of a vehicle performs steering by transmitting a rotational displacement of a steering wheel to a steering gear, and is basically composed of one shaft member. Due to the difficulty of securing a space for arrangement due to the complicated vehicle structure in recent years, a steering shaft is provided with a main shaft to which a steering wheel is attached and an intermediate shaft which is connected to the main shaft via a universal joint so that the axes intersect. Is also configured (for example,
See Japanese Utility Model Publication No. 59-37416).

In a vehicle, when a collision load is applied to a steering gear portion at the time of a collision and the steering gear is moved to the rear side of the vehicle body (that is, the vehicle compartment side), the displacement is directly transmitted to the steering shaft. In order to prevent the steering shaft (that is, the steering wheel) from moving toward the vehicle compartment, it has been attempted to provide the intermediate shaft portion with a shock absorbing function. As a specific method thereof, as disclosed in the above-mentioned publicly known example, the intermediate shaft is composed of two shaft members which are slidably displaceable with each other, and these are connected by shear pins, and the axial force of a predetermined value or more is generated by collision. When the shear pin is broken when is input, a method of absorbing shock by sliding the two shaft members in the contracting direction, or dividing the intermediate shaft into two parts, front and rear, and providing appropriate elasticity between these two parts. The rubber coupling is connected with a bellows-like rubber coupling and the steering force is normally transmitted by the torsional rigidity of the rubber coupling, while the rubber coupling bends when an axial force greater than a predetermined value is input from the steering gear side. There is known a method of absorbing shock by bending and deforming the intermediate shaft.

[0004]

However, these two shock absorbing methods have advantages and disadvantages as will be described later.
However, there are disadvantages, and even if any of these methods is adopted, the shock absorbing performance remains unsatisfactory.

That is, since the steering shaft having such an intermediate shaft is arranged such that the axes of the main shaft and the intermediate shaft intersect with each other as described above, the steering shaft is related to the intermediate shaft. When the axial force due to the collision is transmitted to the main shaft, the axial force is input in an inclined direction with respect to the axis of the main shaft. Therefore, when the load input from the intermediate shaft to the main shaft is large, the main shaft is displaced in the tilting direction due to the large load. For example, when an airbag device is attached to the steering wheel, the occupant of the airbag may be displaced. There arises a problem that the constraint point deviates from the design point. Therefore, from this point of view, the smaller the axial force input from the intermediate shaft side to the main shaft side, the better.

On the other hand, from the viewpoint of impact force absorption performance, when an axial force is input by a collision with the intermediate shaft,
It can be said that the larger the deformation stroke of the intermediate shaft, the better.

Comparing the above two shock absorbing methods from the above two viewpoints, first, in the former one equipped with a slide type intermediate shaft, the steering force causes, for example, two shaft members to be serrated. Since it can be supported by the shear pin, the shear resistance of the shear pin can be set to a relatively low value.Therefore, when a relatively small axial force is applied at the time of collision, the shear pin breaks and the two shaft members are separated. The impacts are absorbed by sliding each other in the contraction direction, so that the load transmitted to the main shaft side is small and the tilt displacement of the main shaft is also suppressed. However, on the other hand, since the two shaft members are configured to slide in the axial direction, there is a space limitation, and the slide stroke cannot be made very large. .

On the other hand, in the latter method of utilizing the flexural deformation of the rubber coupling, since it is the flexural deformation, it is easy to take a relatively large deformation stroke, and the shock absorbing performance is taken into consideration. Then it is superior to the former one. However, in this system, since the steering force is transmitted by the rigidity of the rubber coupling, it is necessary to set the rigidity of the rubber coupling relatively high, and therefore the rubber coupling portion is flexibly deformed. A relatively large axial force is applied until the start of the process, and the transmission force from the intermediate shaft to the main shaft is correspondingly increased. Therefore, there is a drawback that problems such as tilt deformation of the main shaft become significant.

The load at the time of starting the shock absorbing action such as the axial force when the shear pin breaks and the axial force when the rubber coupling starts flexural deformation is generally called "collapse load". Therefore, it will be appropriately used in this specification.

In view of the above problems of the prior art, in the present invention, the collapse load of the main shaft is prevented by setting the collapse load low, and the shock absorbing performance is improved by ensuring a large deformation stroke of the intermediate shaft. The purpose of this was to provide a vehicle steering shaft that is compatible with both.

[0011]

According to the invention of claim 1, as a concrete means for solving such a problem in the invention of the present application, a steering wheel is attached to one end of the invention and is rotatable by a steering column attached to the vehicle body side. A main shaft supported by the intermediate shaft having one end connected to the other end of the main shaft via a first universal joint and the other end connected to the steering gear side via a second universal joint. In a steering shaft of a vehicle, the intermediate shaft is composed of a plurality of shaft members slidable in the axial direction, and the plurality of shaft members are rupturablely connected by shear pin members, and the plurality of shaft members are rupturable. On at least one side of the shaft member A weak portion is formed, and further, a slide regulating member is provided to regulate the displacement at a predetermined stroke position when the plurality of shaft members slide in the contraction direction due to the breaking of the shear pin member from the connected state by the shear pin member. Is characterized by.

According to a second aspect of the present invention, in the steering shaft for a vehicle according to the first aspect, the weak portions are provided on the plurality of shaft members, respectively, and the slide restricting member is provided to reduce the plurality of shaft members. The fragile portions provided on the plurality of shaft members are configured to substantially overlap in the axial direction when the slide is restricted.

[0013]

With each of the inventions of the present application, the following effects can be obtained by adopting such a configuration.

According to the first aspect of the present invention, when a collision load is input as an axial force from the steering gear side to the intermediate shaft due to a vehicle collision, the shear pin member breaks when the collapsing load reaches the collapse load and the first shaft member and The second shaft member slides relative to the contracting direction, and the impact force is absorbed and relaxed. Therefore, since the load more than the collapse load does not act on the main shaft from the intermediate shaft, the main shaft is not deformed in the falling direction even when the axes of the intermediate shaft and the main shaft intersect. It is a thing.

When the sliding stroke of the first shaft member and the second shaft member in the contracting direction reaches a predetermined value, the slide restricting member is actuated to restrict the sliding action of each shaft member and act on the intermediate shaft. However, in this case, the stress of the fragile portion provided on at least one of the first shaft member and the second shaft member locally increases due to this load, and the intermediate shaft at the fragile portion is increased. Will be bent and deformed. As a result, the deformation stroke of the intermediate shaft is the sum of the deformation due to the slide deformation and the bending deformation at the fragile portion, which is greater than the deformation stroke due to either one of them.

According to the second aspect of the invention, the fragile portions are provided on both the first shaft member and the second shaft member, and at the time of actuation of the slide restricting member, they substantially overlap in the axial direction. The fragile portion has a large reduction in rigidity when viewed from the whole, and therefore, the bending load is smoother with a smaller collapse load than in the case of the above-mentioned claim 1.

[0017]

Therefore, according to the steering shaft of the vehicle of each invention of the present application, since the collapse load is small,
It is possible to reliably prevent the main shaft from falling and deforming due to the load transmitted from the intermediate shaft.For example, in a vehicle equipped with an airbag on the steering wheel portion, the airbag protects the occupant protection performance. There is an effect that the safety of can be further improved.

Further, since the deformation stroke of the intermediate shaft at the time of collapse can be made large, the impact force due to the collision applied to the intermediate shaft can be absorbed more smoothly and surely, and the transmission of the impact force to the steering wheel side can be suppressed. There is also the effect that you can.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steering shaft for a vehicle according to the present invention will be specifically described below with reference to the embodiments shown in the accompanying drawings. FIG. 3 shows a steering device for a vehicle equipped with a steering shaft 1 according to the embodiment of the present invention. The parts are shown. This steering shaft 1 has one end 2a
A main shaft 2 having a steering wheel 4 attached to the main shaft 2 and one end 3a at the other end 2b of the main shaft 2.
Has an intermediate shaft 3 which will be described later and is connected via a first universal joint 5. The main shaft 2 is the steering support member 1 on the vehicle body side.
The steering column 10 is rotatably fitted in and supported by the steering column 10 supported by the bracket 2 via the bracket 11. Further, the other end 3b of the intermediate shaft 3 meshes with a steering gear 9 in a steering gear box 8 arranged in the vehicle width direction and rotates the steering gear 9 to rotate the pinion shaft 7 for steering. Are connected via.

Here, the main shaft 2 is arranged obliquely downward toward the front of the vehicle body, and the intermediate shaft 3 is obliquely downward from the other end 2b of the main shaft 2 and laterally in the vehicle width direction. Are arranged in a tilted state in both directions. Therefore, when a collision load is applied to the steering gear box 8 by the collision of the vehicle and the steering gear box 8 moves to the rear side of the vehicle body, a predetermined axial force is applied to the intermediate shaft 3 connected to the pinion shaft 7, and The axial force is transmitted to the main shaft 2 obliquely from below. For this reason, if the load shaft force is not absorbed and relaxed in the intermediate shaft 3, a large load is applied to the main shaft 2 to move the main shaft 2 to the passenger compartment side or to cause lateral deformation and deformation. . Therefore, in this embodiment, by applying the present invention to the intermediate shaft 3 and implementing a unique new structure, it is possible to promote the absorption and relaxation action of the impact force and prevent the main shaft 2 from falling and deforming. I have to. Hereinafter, a specific structure of the intermediate shaft 3 and its function and effect will be described in detail with reference to FIGS. 1 and 2.

As shown in FIG. 1, the intermediate shaft 3 has a composite structure composed of a first shaft member 31 and a second shaft member 32 which will be described later.

The first shaft member 31 is composed of a cylindrical body having serrations formed on its inner peripheral surface, and
One end 31a thereof (that is, one end 3a of the intermediate shaft 3) is connected to one end of the second universal joint 6 via a connecting pin 30. On the other hand, the second shaft member 3
2 is formed by forming serrations on the outer peripheral surface of a shaft body having a predetermined length that can be inserted into the first shaft member 31. Then, one end 32a of the second shaft member 32
Is serrated to the second shaft member 32 while being inserted into the first shaft member 31, and the other end 32b is serrated to one end of the second universal joint 6.

The first shaft member 31 and the second shaft member 31
The shaft member 32 is connected by a shear pin member 40 in a state where a predetermined stroke S is secured between the end surface 35 of the second shaft member 32 on the side of the one end 32 a and the connecting pin 30. The shear pin member 40 is
An annular base member 41 fitted and arranged in an annular recess 37 formed on the outer peripheral surface of the second shaft member 32, and a plurality of pin portions protruding on the outer peripheral surface of the base member 41 at a predetermined pitch in the circumferential direction. 42, 42, ... And each of the pin portions 42, 42, ... Is fitted into a plurality of pin receiving holes 38, 38 ,. The 1st shaft member 31 and the 2nd shaft member 32 are connected. The pin portion 42 of the shear pin member 40
The breaking force of is set to a relatively small value.

Further, the first shaft member 31 and the second shaft member 31
Of the shaft members 32, the first shaft member 31 is
.. of a predetermined size are formed at predetermined intervals in the circumferential direction at a position closer to the first universal joint 5 side than a mounting position of the shear pin member 40 on the outer peripheral wall thereof. An annular groove 34 of a predetermined size is formed on the outer peripheral surface of the second shaft member 32 at a position closer to the second universal joint 6 than the mounting position of the shear pin member 40. The relative formation positions of the openings 33, 33, ... On the side of the first shaft member 31 and the annular grooves 34, 34, ... on the side of the second shaft member 32 are as shown in FIG. The axial distance S ₁ in the state where the both are connected by the shear pin member 40 is the stroke S
Is set to almost match. The opening 33 of the first shaft member 31 and the annular groove 34 of the second shaft member 32 correspond to the fragile portion in the claims.

In the intermediate shaft 3 thus constructed, the first shaft member 3 is normally operated (when there is no collision).
Due to the serration connection between the first shaft member 32 and the second shaft member 32, the rotational force (steering operation force) on the main shaft 2 side is transmitted via the intermediate shaft 3 to the pinion shaft 7
Transmitted to the side. Therefore, since the shear pin member 40 does not receive any rotational force, the shear pin member 40 is set in consideration of only the shearing force acting between the first shaft member 31 and the second shaft member 32 at the time of collision when setting the strength thereof. The strength can be reduced to a considerably small value.

When the vehicle collides in this state, the collision force is applied to the intermediate shaft 3 as the axial force from the steering gear box 8 side. In this case, when the axial force reaches a shearing force that causes the pin portion 42 of the shear pin member 40 to break (that is, when a collapse load is reached), the pin portion 42 breaks and the first shaft member 31 is thereby broken. Since the connecting action between the second shaft member 32 and the second shaft member 32 is released, the second shaft member 32 slides in the direction in which it is fitted into the first shaft member 31 (direction of arrow F), thereby absorbing and relaxing the collision force. It works like it does. In this case, since the strength performance of the shear pin member 40 is set to be relatively low as described above, the collapse load can be suppressed to a relatively small value. Therefore, the main shaft 2 is surely prevented from being displaced in the tilting direction due to the load transmitted from the intermediate shaft 3, and in the case of the one provided with the airbag device as described above, the occupant of the airbag is prevented. The protection performance can be improved.

As the second shaft member 32 slides toward the first shaft member 31 as described above, the collision force is absorbed and relaxed, but the stroke amount is naturally limited due to the arrangement space and the like. In the case of the embodiment, the limit is to secure the stroke S as described above, and as shown in FIG. 2, when the sliding amount of the second shaft member 32 reaches the stroke S, the second shaft member 3
The second end surface 35 abuts on the connecting pin 30 to prevent further sliding (that is, in this embodiment,
The end face 35 and the connecting pin 30 constitute a slide regulating member in the claims). Therefore, the shock absorbing action due to the sliding of the second shaft member 32 cannot be expected any more.

However, in this embodiment, when the stroke S is reached and the slide of the second shaft member 32 is restricted, the first shaft member 3 is stopped at that time.
.. and the annular groove 34 of the second shaft member 32 substantially overlap in the axial direction. For this reason, the rigidity of this overlapped portion becomes extremely lower than that of the other portions. Therefore, when axial force is generated in the intermediate shaft 3 due to the slide restriction of the second shaft member 32, stress is applied to the overlapped portion. Due to the concentration, the main shaft 2 is bent and deformed laterally in the overlapping portion as shown by the chain line in FIG. Therefore, the bending stroke of the intermediate shaft 3 further secures the deformation stroke at the time of collapse, and as a result, a larger deformation stroke can be obtained as compared with the case where the bending deformation does not occur. As a result, the collision force is increased. The absorption and relaxation action of is significantly improved, and the safety at the time of collision is further enhanced.

In this embodiment, the second shaft member 32 is made of a solid shaft, but in other embodiments, it may be made of a cylindrical body. Further, as a method of forming the fragile portion in the case where the second shaft member 32 is configured by the tubular body as described above,
For example, a method of locally reducing the wall thickness or forming a slit on the peripheral wall can be considered.

Furthermore, by appropriately adjusting the dimensions of the opening 33 formed in the first shaft member 31 and the annular groove 34 formed in the second shaft member 32, the size of the fragile portion at the time when these are overlapped is reduced. The rigidity of can be set arbitrarily. That is, it is possible to arbitrarily change and set the relative relationship between the collapse load and the deformation stroke characteristic at the time of bending deformation by the above dimension adjustment, which means that various types of vehicles with different structures (e.g., engine size It is a useful technique for applying the present invention to vehicles of different sizes or vehicles having different engine layouts with respect to the vehicle body) to obtain optimum characteristics for these various vehicles.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of a steering shaft of a vehicle according to an embodiment of the present invention.

FIG. 2 is a state change diagram of the steering shaft shown in FIG.

FIG. 3 is a side view showing the entire steering shaft of the vehicle according to the embodiment of the present invention.

[Explanation of symbols]

1 is a steering shaft, 2 is a main shaft, 3 is an intermediate shaft, 4 is a steering wheel, 5 is a first universal joint, 6 is a second universal joint, 7 is a pinion shaft, 8 is a steering gear box, 9 is a steering gear, 10 is a steering column, 11 is a bracket, 12 is a steering support member, 30 is a connecting pin, 31 is a first shaft member, 32 is a second shaft member, 33 is a hole, 34 is an annular groove, 35 is an end face, and 37 is An annular concave portion, 38 is a pin receiving hole, 40 is a shear pin member, 41 is a base member, and 42 is a pin portion.

Claims (2)

[Claims] 1. A main shaft having a steering wheel attached to one end thereof and rotatably supported by a steering column attached to a vehicle body, and one end thereof connected to the other end of the main shaft via a first universal joint. A steering shaft of a vehicle, the other end of which is connected to the steering gear side via a second universal joint, the plurality of shafts being configured to be slidable in the axial direction. A plurality of shaft members, the plurality of shaft members are rupturablely connected to each other by a shear pin member, and a fragile portion is formed on at least one side of the plurality of shaft members, and the plurality of shaft members are the shear pin. From the state of connection by members, the shear pin Vehicle steering shaft, characterized in that the displacement in the case of sliding in the reduction direction is provided the slide regulating member for regulating at a predetermined stroke position by rupture of the wood. 2. The plurality of shaft members according to claim 1, wherein the fragile portions are respectively provided on the plurality of shaft members, and the plurality of shaft members are restricted from sliding toward the contraction side by the slide restricting member. A steering shaft for a vehicle, wherein each fragile portion provided on the shaft member is configured to substantially overlap in the axial direction.