JP3852268B2 - Electric position adjustment type steering device and method for machining screw gear thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric position adjustment type steering apparatus for an automobile including a tilt column, a telescopic column, or a tilt / telescopic column apparatus, and more particularly, an electric position adjustment including a rod drive mechanism including a screw gear applied to the column apparatus. The present invention relates to a type steering apparatus and a method for processing a screw gear thereof.
[0002]
[Prior art]
Conventionally, an electric position adjustment type steering device can adjust the position of the steering wheel by the driving force of the electric motor. This device includes a type in which the steering wheel tilts and an axial direction. A method of moving (telescopic) is known. In any of these types, the screw shaft is connected to the upper column, the nut member screwed to the screw shaft is rotatably supported on the bracket, and the screw shaft is rotated by an electric motor. It is a mechanism that adjusts the position of the steering wheel by moving.
[0003]
As an example of this electric position adjustment type steering device, in Japanese Utility Model Publication No. 5-29979, as shown in FIG. 8, a bracket in which a lower shaft 31 having one end connected to a steering gear (not shown) is fixed to a vehicle body. 30 and the lower column 32 are rotatably accommodated, and an upper shaft (not shown) having a steering wheel (not shown) at one end is rotatably accommodated in the upper column 33. The other end of the lower shaft 31 and the upper shaft The upper column 33 is connected to one end of a screw shaft (actuator rod) 40 having a screw portion 40a at one end substantially parallel to both columns, and the screw portion of the screw shaft 40 is connected to the upper column 33. 40a is supported by a housing 34 fixed to the bracket 30 so as to be rotatable and immovable in the axial direction of the screw shaft 40, and a gear portion 44a is formed on the outer peripheral portion. The female screw hole 44 b of the screw gear (nut member) 44 is screwed, and the screw gear 44 is rotationally driven by the electric motor 60 to move the screw shaft 40 in the axial direction. The column 33 is adjusted in a range of an angle α around the axis 16 of the column 33, and is brought into contact with the screw shaft 40 from a direction substantially perpendicular to the longitudinal direction thereof so that the screw shaft 40 is in one radial direction with respect to the screw gear 44. An electric position adjustment type (tilt) steering device provided with biasing means 41 and 43 for biasing is disclosed.
[0004]
In this configuration, the screw portion 40a of the screw shaft 40 is pressed against the screw gear 44 in the radial direction by the action of the urging means 41 and 43, and the screwed portions of both members are brought into pressure contact with each other. The left and right tooth surfaces of the mountain are pressed and contact each other at the same time to prevent backlash of the screwed portion, and the hinge portion 72 of the screw shaft 40 is pressed unilaterally to obtain a biased contact without backlash. It is done.
[0005]
[Problems to be solved by the invention]
However, in the conventional electric position adjustment type steering device, the screw gear 44 is made of the same metal as the screw shaft 40 screwed into the screw gear 44, and since these have the same thermal expansion coefficient, In some cases, the screwing did not become tight, but for smooth rotation, even a slight gap between the screw gear 44 and the screw shaft 40 is necessary. Therefore, it is difficult to completely eliminate the backlash of the screw shaft 40.
[0006]
Therefore, as shown in FIGS. 9 and 10, the applicant of the present invention has a gear portion 45a having a gear formed on the outer peripheral portion, a bearing portion 45b extending on both sides in the axial direction of the gear portion 45a, and a female portion. A screw gear 45 formed of a screw hole 45c is integrally formed of resin. As shown in the case where the screw shaft 40 of FIG. 11 is screwed, the screw gear 45 may be set so that there is no backlash, including a gap and a screw fitting length, mainly in the axial direction at room temperature. it can.
[0007]
However, since the thermal expansion coefficients of resin and iron differ by an order of magnitude, the gear meshes tightly at low temperatures by simply threading, including screw molding in injection molding of resin screw gear 45. There is a problem that the operability is lowered.
In addition, if the effective diameter of the female screw hole is increased to the extent that the screw gear 45 is contracted and tightened at a low temperature, and the size is added with the white, the meshing will not be properly engaged at the normal temperature and the play will increase. It was.
[0008]
The present invention improves the inconveniences of the conventional example, and provides an electric position adjusting type steering column device having a simple structure that has no play at room temperature or higher and has good operability even at low temperatures, and a method for machining the screw gear thereof. The challenge is to do.
[0009]
[Means for Solving the Problems]
To achieve the above-described problems, the invention of claim 1, one end steering gear is coupled to, and the steering shaft having a steering wheel at the other end, the steering column for rotatably supporting the steering shaft, the steering An electric actuator that drives the column and adjusts the position of the steering shaft,
The electric actuator is connected to the steering column, has a screw shaft having a male threaded portion at one end, and a Nejigiya that have a female threaded hole to be screwed to the male screw portion, rotationally driving the Nejigiya by an electric motor by moving the screw shaft in the axial direction and, by driving the steering column for adjusting the position of the steering shaft, the electric position adjustable steering device,
The screw gear includes a gear portion having a gear formed on an outer peripheral portion and bearing portions extending on both sides in the axial direction of the gear portion, and both the bearing portions of the screw gear have axial directions around their respective axes. slit is provided in a form that opens to the bearing portion both ends of, and, the female screw hole of the Nejigiya, rather than the central portion of the effective diameter is located, the gear unit, the bearing portion both ends from the center portion It is characterized by being shaped so as to gradually become smaller .
[0010]
As a result, at normal temperatures, both ends of the bearing have a normal effective diameter (minimum diameter) that does not add the amount of tightening, so there is no gap between the female screw hole and the male screw. The play of time can be eliminated. In addition, since the effective diameter of the center of the screw gear is increased by the tightening diameter at the normal temperature (maximum diameter), the engagement does not become tight even when this part is tightened at low temperatures. However, since the tightening method is relaxed by the slit, the meshing of this portion does not become excessively tight. Therefore, backlash during driving can be eliminated even at low temperatures.
[0011]
In the invention of claim 3 , a steering gear is connected to one end, a steering shaft having a steering wheel at the other end, a steering column that rotatably supports the steering shaft, and the steering column is driven to drive the steering shaft. An electric actuator that adjusts the position of
The electric actuator is connected to the steering column and has a screw shaft having a male screw portion at one end and a screw gear having a female screw hole screwed into the male screw portion, and the screw gear is driven to rotate by an electric motor. A screw gear machining method for manufacturing the screw gear for an electric position adjusting type steering device, wherein the screw shaft is moved in an axial direction to drive the steering column to adjust the position of the steering shaft,
It consists of a gear part having a female screw hole and a gear formed on the outer peripheral part and bearing parts extending on both sides in the axial direction of the gear part, and an axial slit is formed around the axis of the both bearing parts. Form a screw gear blank provided in a form that opens on both ends of the bearing,
A female screw hole of the screw gear blank while supporting the screw gear blank in a stationary state by a jig having an inner peripheral surface arranged with a predetermined gap between the outer peripheral surface of the bearing portion of the screw gear blank. The female screw hole is shaped so that its effective diameter gradually becomes smaller from the central portion toward both ends of the bearing portion than the central portion where the gear portion is located. It is a feature.
According to such a processing method, when the tap is passed through the female screw hole, the bearing portion elastically escapes to the outer peripheral side by the action of the slit, and then returns to the original position. The female screw hole whose effective diameter changes as described above can be formed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an electric position adjusting type steering apparatus showing an embodiment of the present invention, FIG. 2 is a cross-sectional configuration diagram showing an electric tilt actuator, FIG. 3 is a side cross-sectional view showing a screw gear, and FIG. FIG. 5 is a perspective view showing the screw gear, FIG. 7 is a side sectional view showing a method for forming the female screw hole of the screw gear, and FIG. 6 is a side sectional view showing a state where the screw shaft is screwed into the screw gear. FIG.
[0013]
The steering device 1 of FIG. 1 employs a so-called hip swing tilt method, and a steering shaft 3 having a steering wheel 2 attached to a rear end portion and a steering gear (not shown) connected to a front end portion is provided. Two steering columns, that is, an upper column 4 and a lower column 6 that are rotatably held around a shaft, and a fixed bracket 5 that is fixed to the vehicle body side are provided. By appropriately adjusting the inclination of the columns 4 and 6 with respect to the fixed bracket 5 and the relative position between the columns 4 and 6, the steering shaft 3 and thus the steering wheel 2 can be held at a desired position. Yes.
[0014]
The upper column 4 is a steel pipe press-formed product, and rotatably holds the steering shaft 3 via a bearing (not shown) and is slidably fitted and held in the lower column 6. The lower column 6 is a thin die-cast molded product (hereinafter referred to as an aluminum die-cast molded product) made of an aluminum alloy, and has a large number of ribs on the outer peripheral surface in order to ensure rigidity. The lower column 6 is swingably connected to the front end portion of the fixed bracket 5 via a tilt hinge pin 8. Therefore, the tilt position of the steering shaft 3 and the steering wheel 2 can be adjusted by appropriately swinging the lower column 6 with respect to the fixed bracket 5. In the present embodiment, the fixed bracket 5 is also an aluminum die cast product similar to the lower column 6.
[0015]
In the case of this embodiment, the tilt position of the steering wheel 2 is adjusted by the electric tilt actuator 7. The electric tilt actuator 7 has a front end portion of an actuator body 71 connected to a lower column 6 via a pin 17 so as to be swingable, while a rear end portion of the actuator rod 14 is connected to a tilt swing member of a steel plate press-formed product by a pin 18. 19 is connected to the front end. The tilt swing member 19 is supported by the fixed bracket 5 so as to be swingable by the pin 22 at the upper middle portion, and the pin 24 fixed to the lower column 6 is fitted into the rectangular hole 23 formed in the rear end portion. ing.
[0016]
Thus, when the actuator rod 14 is drawn out from the actuator body 71 of the electric actuator 7, the tilt swing member 19 rotates counterclockwise in FIG. 1, and the lower column 6 together with the upper column 4 and the steering shaft 3 is tilted hinge pin. As a result, the steering wheel 2 swings upward with the fulcrum 8 as a fulcrum, and the tilt adjustment of the steering wheel 2 upward is performed. When the actuator rod 14 is housed in the actuator main body 71 of the electric tilt actuator 7, the tilt swing member 19 rotates clockwise in FIG. 1, and the lower column 6 tilts together with the upper column 4 and the steering shaft 3. The hinge pin 8 is pivoted downward and the steering wheel 2 is tilted downward.
[0017]
On the other hand, since the upper column 4 is slidably fitted and held in the lower column 6, the telescopic position of the steering shaft 3 and the steering wheel 2 is adjusted by extending or entering the upper column 4 with respect to the lower column 6. can do.
[0018]
In the present embodiment, the telescopic position of the steering wheel 2 is adjusted by the electric telescopic actuator 107. The electric telescopic actuator 107 is exactly the same as the electric tilt actuator 7, and only the mounting form is different. That is, the electric telescopic actuator 107 includes a steel plate stay 155 in which a front end portion of an actuator body 171 is connected to the lower column 6 via a pin 117 and a rear end of the actuator rod 114 is fixed to the upper column 4 via a pin 118. It is connected to.
[0019]
As a result, when the actuator rod 114 is extended from the actuator body 171 of the electric telescopic actuator 107, the upper column 4 and the steering shaft 3 move backward together with the stay 155, and the telescopic adjustment to the rear of the steering wheel 2 is performed. When the actuator rod 114 is housed in the actuator body 171 of the electric telescopic actuator 107, the upper column 4 and the steering shaft 3 move forward together with the stay 155, and telescopic adjustment to the front of the steering wheel 2 is performed.
[0020]
As shown in FIG. 2, the electric tilt actuator 7 and the electric telescopic actuator 107 are composed of an electric motor 9 and a rod drive mechanism 13, an actuator body 11 of an aluminum die cast product used for holding them, and the like. . The rod drive mechanism 13 mainly includes a screw gear 10 that is rotatably held in a housing 11 that is an actuator body via a pair of bearings 12 and is not movable in the axial direction, and a female formed on the axis of the screw gear 10. A male screw that is screwed into the screw 10c includes a hollow actuator rod (screw shaft) 14 having a male screw portion 14a formed on the outer peripheral surface. A driving force is transmitted to the screw gear 10 through an idler gear 16 from a drive gear 15 attached to the shaft of the electric motor 9.
[0021]
As shown in the perspective views of FIGS. 3, 4, and 5, the screw gear 10 includes a gear portion 10 a in which a gear is formed and a bearing portion 10 b that extends on both sides in the axial direction across the gear portion 10 a. And a female screw hole 10c formed in the shaft center of the gear portion 10a. The bearing portion 10b is provided with three slits 10d in the axial direction at equal intervals around the axis so as to open to both ends of the bearing portion 10b. As shown in FIG. 3, the effective diameter of the female screw hole 10c is set to a maximum diameter Rmax obtained by adding a tightening s s that is an amount of the central portion where the gear portion 10a is located and contracted at a low temperature. Both ends are set to a minimum diameter Rmin that does not cause a gap at room temperature, and is formed so as to gradually change from the maximum diameter Rmax to the minimum diameter Rmin.
[0022]
As shown in FIG. 6, when the male screw portion 14a of the actuator rod 14 is screwed into the screw gear 10 having the female screw hole 10c having such a shape, both end portions of the bearing portion 10b, that is, female Since the opening end of the screw hole 10c has a normal effective diameter that does not add the amount of the tightening margin s to a negative effective diameter, there is no gap in the engagement between the female screw hole 10c and the male screw portion 14a, and there is no play. Drive becomes possible. Further, at the time of low temperature, the effective diameter of the central portion of the screw gear 10 is increased by the tightening slab s, so that the engagement does not become tight even when tightened, and the open end of the female screw hole 10c is further tightened. However, since the tightening is relaxed elastically by the slit 10d, the meshing of this portion does not become excessively tight. Therefore, even when the temperature is low, the operability is good and driving without backlash is possible. Although there is thermal contraction in the axial direction of the female screw hole 10c, the bearing portion 10b rotates toward the male screw portion 14a with the base portion of the slit 10d as a fulcrum at a low temperature due to the action of the slit 10d of the bearing portion 10b. Absorb by lightly pressing the male threaded portion 14a in the form.
[0023]
As shown in FIG. 7, the above-described shape of the female screw hole 10c of the screw gear 10 is a conventional female screw hole having a predetermined effective diameter that is tight at the time of low temperature without causing a gap or play mainly in the axial direction at room temperature. 10e can be formed by passing the tap 20 at room temperature. In this case, as shown in the figure, the screw gear 10 is supported in a stationary state by the jig 21, but the surface of the jig 21 that faces the outer peripheral surface of the bearing portion 10 b has a gap d with respect to the outer peripheral surface. It is arranged. The clearance d is set to a degree (d> s) that is slightly larger than the fastening s where the effective diameter of the female screw hole 10c is reduced at low temperatures. The effective diameter of the tap 20 at the normal temperature has a large effective diameter that is obtained by adding a tightening s for reducing the female screw hole 10e at a low temperature.
[0024]
When this tap 20 is passed through the female screw hole 10e at room temperature, the bearing portion 10b escapes to the gap d within the elastic limit by the action of the slit 10d, and the screw is cut slightly shallowly. Then, after the tap 20 passes through the bearing portion 10b, the bearing portion 10b that has escaped into the gap d is elastically returned to the original position, so that both ends thereof have a normal effective diameter that does not add the tightening sill. When the tap 20 passes through the central portion of the female screw hole 10e, there is no escape, so the screw having the larger effective diameter of the tap 20 is cut as it is.
[0025]
Therefore, as shown in FIG. 3, the female screw hole 10c has a maximum diameter Rmax at the center and a minimum diameter Rmin that does not add the tightening s at both ends, and from the maximum diameter Rmax to the minimum diameter Rmin. It is molded into a shape that gradually changes. However, the central portion where the gear portion 10a of the female screw hole 10c is located does not escape at all when the tap 20 passes, and thus becomes a linear cylindrical female screw hole having an effective diameter of the tap 20.
[0026]
Further, as another method of forming the female screw hole 10c, a tap having a normal effective diameter is formed at a low temperature by using a jig similar to that shown in FIG. 7 (a gap d is provided on the outer peripheral surface of the bearing portion 10b). ) Is passed through the female screw hole 10e of the screw gear 10 attached to (1). In this case, when the temperature reaches room temperature, the female screw hole 10e expands, and the female screw hole 10c similar to FIG. 3 can be formed.
[0027]
When the maximum diameter Rmax and the minimum diameter Rmin of the female screw hole 10c are expanded at a high temperature of room temperature or higher, and the gap becomes large, the effective diameter of the opening end of the female screw hole 10c is set to the actuator rod 14 at normal temperature. This can be dealt with by setting it smaller than the effective diameter of the male screw portion 14a. In this case, the female screw hole of the screw gear 10 has an effective diameter obtained by adding the above-described tightening margin s for reducing the female screw hole 10e at a low temperature to the screw gear 10 having a female screw hole having an effective diameter reduced by an amount that expands at a high temperature. It forms by passing the tap 20 which has a diameter at normal temperature. As described above, even when the temperature is higher than the normal temperature, the smooth operation can be performed from the low temperature to the high temperature.
[0028]
【The invention's effect】
As described above, both the bearing portions of the screw gear are provided with a plurality of slits in the axial direction at equal intervals around the shaft so as to open on both ends of the bearing portion, and the effective diameter of the female screw hole is The central part where the gear part is located has the maximum diameter with a tightening squeeze that is tightened at low temperatures, and both ends of the bearing part have a minimum diameter that does not cause a gap at room temperature, and gradually changes from the maximum diameter to the minimum diameter. Therefore, there is no gap between the female screw hole and the male screw on the screw shaft at room temperature or higher, so that play during driving can be eliminated. In addition, at low temperatures, the effective diameter of the central part of the screw gear is increased by the amount of tightening, so even if it is tightened, the meshing will not become tight, and both ends of the bearing part will be relaxed by the slits. The meshing of this part will not be too tight. Therefore, even when the temperature is low, driving without backlash is possible, and good operability can be maintained.
[0029]
In addition, the female screw hole having the effective diameter has a tap having the same effective diameter as the effective diameter of the female screw hole having no play at normal temperature, or is passed through the female screw hole at low temperature, or is tightened at normal temperature at the low temperature. Since the tap with effective diameter added with tightening is passed through the female screw hole with effective diameter without play at the normal temperature, the tap with effective diameter slightly larger than the female screw hole of the screw gear at low temperature or normal temperature The female screw hole whose effective diameter is changed can be formed by a very simple method of passing through the female screw hole.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electric position adjustment type steering column showing an embodiment of the present invention.
FIG. 2 is a cross-sectional configuration diagram showing an electric tilt actuator.
FIG. 3 is a side sectional view showing a screw gear.
4 is a view of the screw gear of FIG. 3 as viewed from the direction of arrow A. FIG.
5 is a perspective view showing the screw gear of FIG. 3. FIG.
FIG. 6 is a side sectional view showing a state where a screw shaft is screwed into a screw gear.
FIG. 7 is a side sectional view showing a method for forming a female screw hole of a screw gear.
FIG. 8 is a side sectional view showing a part of a conventional electric position adjustment type tilt steering column device;
FIG. 9 is a side sectional view showing a conventional screw gear.
10 is a view of the conventional screw gear of FIG. 9 as viewed from the direction of arrow A. FIG.
FIG. 11 is a side sectional view showing a state in which a conventional screw gear and a screw shaft are screwed together.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering column apparatus 2 Steering wheel 3 Steering shaft 4 Upper column 5 Bracket 6 Lower column 9 Electric motor 10 Screw gear 10a Gear part 10b Bearing part 10c Female screw hole 10d Slit
11 Housing 14 Screw shaft (actuator rod)
14a Male thread

Claims (4)

One end steering gear is coupled to, and the steering shaft having a steering wheel at the other end, the steering column for rotatably supporting the steering shaft, and drives the steering column, the electric actuator for adjusting the position of said steering shaft And
The electric actuator is connected to the steering column, has a screw shaft having a male threaded portion at one end, and a Nejigiya that have a female threaded hole to be screwed to the male screw portion, rotationally driving the Nejigiya by an electric motor by moving the screw shaft in the axial direction and, by driving the steering column for adjusting the position of the steering shaft, the electric position adjustable steering device,
The Nejigiya is composed of a bearing portion extending to both sides in the axial direction of the gear portion and the gear portion of the gear is formed on an outer peripheral portion, the bearing portions of the Nejigiya is axially about its axis, respectively slit is provided in a form that opens to the bearing portion both ends of, and, the female screw hole of the Nejigiya, rather than the central portion of the effective diameter is located, the gear unit, the bearing portion both ends from the center portion An electric position-adjustable steering device, wherein the steering device is shaped so as to gradually become smaller . The effective diameter of the female screw hole is determined in consideration of an amount of contraction of the female screw hole due to a temperature change, wherein an effective diameter of a central portion where the gear portion is located is determined. The electric position adjustment type steering apparatus as described. A steering shaft having a steering gear connected at one end and a steering wheel at the other end, a steering column that rotatably supports the steering shaft, and an electric actuator that drives the steering column and adjusts the position of the steering shaft And
The electric actuator is connected to the steering column and has a screw shaft having a male screw portion at one end and a screw gear having a female screw hole screwed into the male screw portion, and the screw gear is driven to rotate by an electric motor. A screw gear machining method for manufacturing the screw gear for an electric position adjusting type steering apparatus, wherein the screw shaft is moved in an axial direction to drive the steering column to adjust the position of the steering shaft,
It consists of a gear part having a female screw hole and a gear formed on the outer peripheral part and bearing parts extending on both sides in the axial direction of the gear part. Form a screw gear blank provided in a form that opens on both ends of the bearing,
A female screw hole of the screw gear blank while supporting the screw gear blank in an immobile state by a jig having an inner peripheral surface arranged with a predetermined gap between the outer peripheral surface of the bearing portion of the screw gear blank. The female screw hole is shaped so that its effective diameter gradually becomes smaller from the central portion toward both ends of the bearing portion than the central portion where the gear portion is located. A featured thread gear machining method. The effective diameter of the female screw hole is determined in consideration of an amount of contraction of the female screw hole due to a temperature change in an effective diameter of a central portion where the gear portion is located. Processing method of screw gear.

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