JPH08215Y2 - Electric tilt steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an improvement in an electric tilt steering device for a vehicle.

Here, the “electric tilt steering device” is a device in which the steering wheel is tilted by driving an electric motor.

(Prior Art and Problems Thereof) As a conventionally known electric tilt steering device, a worm wheel is attached to a tilt pin fixed to an upper column, the worm is meshed with the worm wheel, and the worm is driven by a motor. Some tilt the upper column. However, this conventional example has a drawback in that the backlash of the worm gear is enlarged to cause backlash in the handle wheel portion, which impairs the feeling of rigidity.

Further, as another conventional example, an upper column that rotatably supports an upper steering shaft to which a steering wheel is fixed is pivotally attached to a fixed bracket, and a nut member is screwed to a screw shaft supported by the fixed bracket. There is one in which the nut member and the upper column are connected by a link mechanism, and the screw shaft is rotated by an electric motor. The nut member moves axially as the screw shaft rotates, pivoting the upper column through the link and thus tilting the steering wheel (eg,
JP-A-58-33570 and JP-A-59-230861). This tilting device has an advantage that the force applied to the upper column is received by the nut and the influence of the backlash of the worm gear does not occur.

However, since there are two fulcrums of the link and each fulcrum is fitted with a clearance, the total amount of the clearances of the two fulcrums comes out as backlash. Therefore, there is a problem that the structure becomes complicated, the number of joints increases, the rattling of the steering wheel increases, the rattling feeling easily occurs, the rigidity becomes low, and the space and cost are disadvantageous.

In the conventional tilting device, the upper column moves rotatively, so the locus of movement of the specific point of the upper column draws an arc, and if the nut is directly connected to the upper column without using a link, The moving direction of the nut member serving as the screw shaft does not match the moving direction of the nut member regulated by the upper column. Therefore, an unreasonable force is applied to the fixing portion of the nut member to the fixing bracket, the screwing portion between the nut member and the screw shaft, the connecting portion between the screw shaft and the upper column, and smooth tilting is difficult.

The applicant of the present application previously applied for an electric tilt steering device in Japanese Utility Model Application No. 61-145861 in order to solve the drawbacks of the conventional example.

In this application, an upper column that rotatably supports a steering shaft fixed to an upper end portion of a steering wheel is pivotally attached to a fixing bracket fixed to a vehicle body portion by a tilt pin, and the upper column is partially attached to the upper column. In the electric tilt steering device, which is tilted around the tilt pin via a power transmission member that is connected and is operatively connected to a power source in the other part, the power transmission member and the fixed bracket are provided. A centering mechanism that allows the power transmission member to swing in the tilting direction of the upper column is provided between the two.

According to this prior art example, an unreasonable force is not applied between the power transmission member and the members related thereto at the time of tilting, so that the effect of eliminating rattling can be obtained. But,
Subsequent studies have revealed that there is still room for improvement in the resistance of the power transmission member when it swings, that is, when the steering wheel tilts.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an electric tilt steering device which has an aligning function and has a minimum tilting resistance during tilting. To achieve the above object, in the present invention, in the same electric tilt steering device as in the above-mentioned prior art, the power transmission member is provided between the power transmission member and the fixed bracket in a tilting direction of the upper column. The aligning mechanism that allows the swinging of the power transmitting member includes a nut member screwed to the other end of the power transmitting member and connected to the power source, an aligning portion fixed to the fixing bracket and having an aligning surface, and a nut member. And a thrust bearing interposed between the centering portion and the centering portion, and the sliding contact surface between the thrust bearing and the centering portion is coated with a film made of a material having a small friction coefficient.

In this case, the coating of the above film reduces the resistance when the thrust bearing and the aligning portion are in sliding contact with each other, so that the swing resistance of the power transmission member and the tilting resistance of the upper column are reduced.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 and 2, a fixed bracket 12 having a U-shaped cross section is fixed to a vehicle body portion 10 of a vehicle, and a lower column 14 is fixed to the fixed bracket 12 and an upper portion is tilted by a tilt pin 16. The column 18 is mounted so that it can be tilted. Pin 20 fixed to upper column 18
Extends into the arc hole 22 formed in the bracket 12,
The contact between the side edge of the circular arc hole 22 and the pin 20 causes the upper column 18
The tilt of the is regulated. A lower steering shaft 24 extends in the lower column 14 and the fixed bracket 12, and a lower end portion (left end portion in FIG. 2) of the lower steering shaft 24 is connected to a wheel rolling device (not shown).

On the other hand, the upper end of the lower steering shaft 24 is connected to the upper steering shaft 28 via a universal joint 26. A steering wheel 30 is fixed to an upper end portion (right end portion in FIG. 2) of the upper steering shaft 28. When the steering wheel 30 is rotationally steered, torque is transmitted by the upper steering shaft 28, the universal joint 26, and the lower steering shaft 24, and as a result, wheels (not shown) are steered.

As shown in FIGS. 2 and 3, the fixing bracket
Housing 32 is fixed to the bottom surface of 12 and external thread 38
A screw shaft 40 having a thread extends from the housing 32 toward the upper column 18, and a female screw 45 of a nut member 44 is screwed into the male screw 38. A gear having teeth gently curved to be convex outward at an axially intermediate portion of the nut member 44.
46 are formed.

The housing 32 has a curved portion 52 at the back, and an aligning washer 54 is arranged at the inlet. The inner surface of the curved portion or the centering washer is formed into an arc surface 53 or 55 centered on the nut member 44. Thrust ball bearings 58 and 60 are arranged between the nut member 44 and the curved portion 52 or the centering washer 54, respectively. Each thrust ball bearing includes an inner ring 61 that comes into contact with the nut member 44, an outer ring 62 that is slidable with respect to the curved portion 52 or the alignment washer 54, and a steel ball 63 that is arranged between the two rings. The thrust ball bearings 58, 60 are preloaded from the axial direction by the cover 56 screwed into the inlet portion of the housing 32, and are maintained in the assembled state.

The arcuate surfaces 53, 55 of the curved portion 52 and the aligning washer 54, and the arcuate surface 63 of the outer ring 62 of the thrust ball bearings 58, 60 are coated with a film 80 made of synthetic resin such as Tetron (trademark). .

The worm gear 64 formed on the output shaft 62 of the electric motor 60 fixed to the housing 32 is meshed with the gear 46 of the nut member 44, and when the electric motor 60 is driven,
The output shaft 62 is rotated and the rotation of the worm gear 64 is transmitted to the nut member 44 and is decelerated, and the rotation of the nut member 44 causes the screw shaft 40 to move in the axial direction (left and right direction in FIG. 2, perpendicular to the paper surface in FIG. 3). Direction).

In FIG. 2, both ends of the upper column 18 are fixed to the lower surface of the upper column 18, and a bracket 70 having a U-shaped cross section is fixed. The other end of the screw shaft 40 extends between the bent parts, The ends are pivotally attached to the bracket 70 by pins 72.

 Next, the operation of this embodiment will be described.

When the driver operates a predetermined switch (not shown),
The electric motor 60 operates, the worm gear 64 rotates, and the engagement between the worm gear and the nut member 44 and the nut member 44
The screw shaft 40 is moved in the axial direction through the screw engagement between the screw shaft 40 and the screw shaft 40.

Here, considering the case where the screw shaft 40 moves to the left in FIG. 2, the pin 72 moves to the left.
And the upper column 18 is integrally turned clockwise around the tilt pin 16 so that the positions of the upper steering shaft 28 and the steering wheel 30 are set to a lower position. The tilt amount of the steering wheel 30 is determined by the moving amount of the screw shaft 40 by the electric motor 60, and the maximum tilt amount downward from the neutral position is the pin of the upper column.
20 is determined by contacting the right side edge of the circular arc hole 22 (at this time, the wheel 30 is in the position indicated by 30a in FIG. 1). The swing angle of the pin 72 corresponding to this is indicated by α in FIG.

On the other hand, tilting the steering wheel 30 upwards
The electric motor 60 is rotated in the opposite direction by operating the switch to move the screw shaft 40 to the right in FIG. 2, and the upper column 18, the upper steering shaft 28, and the like are moved to the tilt pin 16.
Achieved by turning left around. The amount of tilt upward from the neutral position of the steering wheel 30 is determined by the pin 20 contacting the left side edge of the circular arc hole 22, and the position of the wheel 30 at this time is indicated by 30b in FIG. is there. The swing angle of the pin 72 corresponding to this is indicated by β in FIG.

When the bracket 70 is tilted by the movement of the screw shaft 40, the pin 72 moves on an arc centered on the tilt pin 16, and the pin 72, that is, the other end of the screw shaft 40 is substantially in the axial direction of the screw shaft 40. Displaced slightly in the orthogonal direction (the tilting direction of the upper column 18), so that the entire screw shaft 40 is
It will be slightly swung about the part accommodated in 32. Therefore, at this time, the screw shaft 40 and its related members
No unreasonable force will occur between 32 and 70 mag.

The screw shaft 40 smoothly rocks with respect to the housing 32 during rocking in any of the above directions. The reason is that the sliding surfaces 53, 63 between the thrust ball bearings 58, 60 and the curved portion 52 and the centering portion 54 are coated with the synthetic resin film 80 having a low friction coefficient.

It is needless to say that the present invention can be changed and improved in a timely manner in addition to the above-described embodiment, particularly within a range in which the gist of the nut member is not impaired. For example,
In the above-mentioned embodiment, both the aligning washer and the outer ring of the thrust ball bearing are coated with synthetic resin, but only one of them may be coated. The types of synthetic resin are:
As long as it has a small friction coefficient, it can be arbitrarily selected and changed in addition to Teflon.

(Effects of the Invention) As described above, an aligning mechanism is provided between the power transmission member that transmits the force for tilting the steering wheel to the upper column and the fixed bracket, and this aligning mechanism is configured. A film made of a material with a small friction coefficient was applied to the sliding contact surface between the thrust bearing and the centering portion. As a result, the swing resistance of the power transmission member, that is, the resistance when the upper column and the steering wheel are tilted is reduced. Further, since the load on the electric motor is reduced, the electric motor can be downsized, the installation space can be reduced, the power consumption can be reduced, and the level of the generated sound can be lowered.

Furthermore, the operation of coating the thrust bearing and the centering portion that form the centering mechanism with a film is easy, and the cost therefor is also low. Further, by coating the film, it becomes easy to manage the dimensions of the nut member, the thrust bearing and the aligning portion (variation in manufacturing dimensions can be adjusted by the film).

In this way, a high-performance and inexpensive electric tilt steering device as a whole can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic external view showing an embodiment of the present invention, FIG. 2 is a sectional view of an essential part of FIG. 1, and FIG. 3 is a sectional view taken along the line III-III in FIG. [Description of symbols of main parts] 10 …… Steering wheel 12 …… Fixed bracket 16 …… Tilt pin 18 …… Upper column 40 …… Screw shaft (power transmission member) 44 …… Nut member 58, 60 …… Thrust bearing 52 , 54 …… Alignment part 53, 55, 63 …… Circular (sliding contact) surface 80 …… Coating

Claims (1)

[Scope of utility model registration request] 1. A column for rotatably supporting a steering shaft fixed to an upper end portion of a steering wheel is pivotally attached to a fixed bracket fixed to a vehicle body portion by a tilt pin, and the upper column is connected to the upper column at one end. And an electric tilt steering device that is tiltable around the tilt pin via a power transmission member that is operatively connected to a power source at the other end, between the power transmission member and the fixed bracket. And a centering mechanism that allows the power transmission member to swing in the tilting direction of the upper column, the centering mechanism being screwed to the other end of the power transmission member and connected to the power source. Nut member, an aligning portion fixed to the fixing bracket and having an arc surface, and a thrust shaft interposed between the nut member and the aligning portion. An electric tilt steering device comprising a bearing and a coating made of a material having a small friction coefficient on the sliding surface between the thrust bearing and the aligning portion.