JP2004044620A - Rack and pinion mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack and pinion mechanism capable of surely controlling backlash without influence of machining errors of a pinion and a rack and obtaining a self-lock mechanism. <P>SOLUTION: A pinion 7 is supported and is also oscillatorily supported by a supporting shaft 2 parallel to a center axis of the pinion 7. When the pinion 7 is brought into contact with the rack 9, the rack and pinion mechanism comprises a swing arm 3 in which a line connecting the supporting shaft 2 and a shaft 6 of the pinion 7 has a predetermined angle against a surface orthogonal to an axis of the rack 9, and a spring element 14 urging the swing arm 3 so as to pressurize the rack 9 with the pinion 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rack and pinion mechanism having a backlash suppression function and a self-locking function.
[0002]
[Prior art]
FIG. 5 shows an example of a conventional rack and pinion mechanism having a backlash suppression function.
The pinion 100 in this rack and pinion mechanism has a configuration in which a main pinion portion 101 and a sub-pinion portion 102 are coaxially overlapped as shown in a cross section in FIG. The main pinion portion 101 and the sub-pinion portion 102 are connected to each other with bolts 103 penetrating through a long hole 101a provided in the main pinion portion 101 with their angular phases shifted from each other.
[0003]
According to the rack and pinion mechanism, the backlash between the pinion 100 and the rack 104 can be suppressed by appropriately adjusting the amount of phase shift between the main pinion 101 and the sub-pinion 102.
Note that instead of the pinion 100 having the overlapping structure, the rack 104 may have the overlapping structure.
[0004]
FIG. 7 shows a rack and pinion mechanism including a tapered gear 200 and a rack 201 that meshes with the tapered gear 200. In such a rack and pinion mechanism, by adjusting the axial position of the tapered gear 200, backlash can be suppressed.
[0005]
[Problems to be solved by the invention]
The rack and pinion mechanism shown in FIG. 5 requires the pinion 100 having a special structure in which the main pinion 101 and the sub-pinion 102 are overlapped. That is, there is a disadvantage that a general-purpose pinion cannot be used.
Further, since the thickness of the pinion 100 is increased, there is a disadvantage that the entire mechanism is increased in size.
Of course, if the thicknesses of the main pinion portion 101 and the sub-pinion portion 102 are reduced, the above-described inconvenience can be avoided. However, in the pinion 100 having the above-described configuration, only one of the main pinion portion 101 and the sub-pinion portion 102 contributes to power transmission. Therefore, when the thicknesses thereof are reduced, the power transmission capacity decreases. Allowable load is reduced.
[0006]
This rack and pinion mechanism also has the following problems. That is, the main pinion portion 101 and the sub-pinion portion 102 shown in FIG. 5 have a processing error such as a variation in pitch height, and the rack 104 also has a variation in pitch height and a bend. .
Therefore, even if the phase difference between the main pinion portion 101 and the sub-pinion portion 102 in the pinion 100 is adjusted so that the backlash at a certain position of the rack 104 is suppressed, it is guaranteed that the backlash at other positions is suppressed. In some cases, negative backlash may occur at other positions, and the mechanism itself may not operate smoothly.
[0007]
On the other hand, the rack and pinion mechanism shown in FIG. 7 requires time and effort to adjust the position of the tapered gear 200. Further, the rack and pinion mechanism has a processing error in the taper gear 200 and a processing error and a bend in the rack 201, so that the taper gear 200 is controlled so that backlash at a certain position is suppressed. Even if the axial position is adjusted, the backlash at other positions may not be suppressed.
[0008]
In view of such circumstances, an object of the present invention is to provide a backlash without requiring a pinion having a special structure or adjusting the axial position of the pinion, and without being affected by processing errors of the pinion and the rack. Another object of the present invention is to provide a highly practical rack-and-pinion mechanism that can suppress the occurrence of a self-locking function.
[0009]
[Means for Solving the Problems]
The rack and pinion mechanism according to the present invention supports the pinion, is swingably supported by a support shaft parallel to the center axis of the pinion, and when the pinion abuts on the rack, the support shaft and the pinion A swing arm disposed so that a line connecting the axis of the pinion is at a predetermined angle with respect to a plane perpendicular to the axis of the rack; and the swing arm such that the rack is pressurized by the pinion. And a spring element for biasing the spring.
[0010]
In a preferred embodiment, a drive gear whose axis is located on an extension of an axis of a support shaft of the swing arm, and a driven gear which is attached to a shaft of the pinion and meshes with the drive gear, are further provided. The power of a gear is transmitted to the pinion via the driven gear.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a rack and pinion mechanism according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a rack and pinion mechanism according to the present invention. FIG. 2 is an internal mechanism diagram excluding the front wall 1a of the casing 1 shown in FIG. 1, and FIG. 3 is a sectional view taken along line AA of FIG.
[0012]
In the rack and pinion mechanism according to this embodiment, a support shaft 2 is protruded from the inner surface of a front wall 1a of a casing 1, and a substantially central portion of a swing arm 3 is rotatably supported at the tip of the support shaft 2. Let me do it. In FIG. 3, reference numeral 4 denotes a bearing interposed between the support shaft 2 and the swing arm 3.
[0013]
The swing arm 3 rotatably supports a drive shaft 6 via a bearing 5 provided at a lower end thereof. The drive shaft 6 is provided so as to be parallel to the support shaft 2, has a pinion 7 formed at one end thereof, and has a driven gear 8 attached to the other end.
The pinion 7 is engaged with the rack 9. The driven gear 8 meshes with a driving gear 11 attached to an output shaft of the motor 10.
[0014]
The rack 9 is guided by a guide member 12 provided on the bottom wall 1b of the casing 1 and can move in the left-right direction in FIG.
The motor 10 is attached to the rear wall 1c of the casing 1 such that the axis of the output shaft (the axis of the gear 11) is located on the extension of the axis of the support shaft 2.
[0015]
As shown in FIG. 2, a spring receiving member 13 is provided on an upper wall 1 d of the casing 1, and a repulsion spring 14 is interposed between the spring receiving member 13 and an upper end of the swing arm 3. The swing arm 3 is urged in the counterclockwise direction in FIG. 2 by the elastic force of the repulsion spring 14.
[0016]
Next, the operation of the rack and pinion mechanism according to the present invention having the above configuration will be described.
The swing arm 3 can swing about the support shaft 2. In FIG. 4, the posture of the swing arm when the pinion 7 contacts the rack 9 is shown by a solid line.
As shown in FIG. 4, when the pinion 7 contacts the rack 9, the line connecting the support shaft 2 and the axis of the pinion 7 is at a predetermined angle with respect to a plane perpendicular to the axis of the rack. The arm length (the length of the line) is set so as to form the angle θ.
Therefore, for example, when the swing arm 3 swings from the position indicated by the solid line to the position indicated by the chain line, the center point of the pinion 7 moves from the position P ₁ to the position P ₂ , that is, displaces downward by L. Will do.
[0017]
The swing arm 3 is urged in the counterclockwise direction in FIG. Therefore, the pinion 7 comes into pressure contact with the rack 9 by the elastic force of the spring 14. In other words, the rack 9 is pressurized by the pinion 7.
As described above, the pinion 7 supported by the swing arm 3 can be displaced along a circumference having a line connecting the support shaft 2 and the axis of the pinion 7 as a radius. Therefore, the preload acts not only on the pitch plane direction of the rack 9 but also on the axial plane direction of the pinion 7 and the rack 9.
[0018]
When the motor 10 operates, its rotational power is transmitted to the pinion 7 via the drive gear 11, the driven gear 8, and the drive shaft 6, so that the rack 9 is driven in the left-right direction in FIG. You.
At this time, since the rack 9 is always pressurized by the pinion 7 in the pitch plane direction and the axial plane direction, even if the pinion 7 and the rack 9 have a processing error such as a variation in pitch height, In addition, even when their assembling accuracy is low, they can be operated smoothly without backlash.
[0019]
Incidentally, as described above, the axis of the output shaft of the motor 10 (the axis of the drive gear 11) is located on an extension of the axis of the support shaft 2. Therefore, when the swing arm 3 swings, the center of the driven gear 8 moves on a predetermined circumference centered on the axis of the drive gear 11. This means that the meshing state of the two gears 8 and 11 is maintained well even when the swing arm 3 swings.
[0020]
The rack and pinion mechanism can appropriately adjust the lost motion by changing the strength of the spring 14. Of course, the strength of the spring 14 is set to a value that does not impede the thrust of the rack 9 converted from the output of the motor 10.
The swing arm 3 may swing from the state shown in FIG. 2 in a counterclockwise direction (a direction in which the spring 14 is compressed) in accordance with the operation of the rack or a change in the state of the load. Then, depending on the degree of the swing, the meshing state between the pinion 7 and the rack 9 may be released. Therefore, in this embodiment, a stopper 15 for stopping the swing, which makes the upper end portion of the swing arm 3 abut before the pinion 7 and the rack 9 are disengaged, is provided on the upper wall 1d of the casing 1. .
[0021]
Next, the cell lock function will be described. In FIG. 2, when a right external force is applied to the rack 9, a counterclockwise rotation force is generated on the swing arm 3, and the pinion 7 is strongly pressed against the rack 9 to lock the rack 9. That is, since the pinion 7 functions as a wedge for the rack 9, the rack 9 is locked and the position of the rack 9 is maintained.
[0022]
Thus, according to the rack and pinion mechanism according to this embodiment, a self-lock function based on the wedge action of the pinion 7 is obtained. Therefore, if the rack 9 in FIG. 2 is installed in such a manner that the right end thereof faces downward, the drop of the rack 9 is reliably prevented irrespective of the state of the motor 10 or the state of the reduction element composed of the driven gear and the drive gear 11. You.
The locking action of the rack 9 is generated by an external force applied to the rack 9 in one predetermined direction, and does not lock the power transmission system of the motor 10. Therefore, if the motor 10 is rotated forward and backward, the rack 9 can be smoothly reciprocated.
As described above, if the rack 9 in FIG. 2 is installed so that the right end thereof faces downward, the position of the rack 9 can be adjusted by performing an operation of raising the rack 9 by an external force.
[0023]
【The invention's effect】
According to the rack and pinion mechanism according to the present invention, since the rack is pressurized by the pinion, even if a processing error such as a variation in pitch height exists in the pinion and the rack, the assembling accuracy thereof is also reduced. Even if it is low, the backlash can be suppressed and the rack can be smoothly reciprocated.
In addition, since the rack has a self-locking function, if the rack is installed and used so as to be locked by the action of a downward external force, it is possible to prevent the rack from dropping. In addition, when the rack is installed as described above, the position of the rack can be adjusted by performing an operation of raising the rack with an external force.
In addition, the rack and pinion mechanism according to the present invention does not require a specially configured pinion and does not require adjustment of the axial position of the pinion.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a rack and pinion mechanism according to the present invention.
FIG. 2 is an internal configuration diagram of a rack and pinion mechanism shown without a front wall of a casing.
FIG. 3 is a sectional view taken along line AA of FIG. 1;
FIG. 4 is a schematic diagram showing a displacement mode of a pinion.
FIG. 5 is a conceptual diagram showing an example of a conventional rack and pinion mechanism.
6 is a sectional view of a pinion in the rack and pinion mechanism shown in FIG.
FIG. 7 is a conceptual diagram showing another example of a conventional rack and pinion mechanism.
[Explanation of symbols]
Reference Signs List 1 casing 2 support shaft 3 swing arm 6 drive shaft 7 pinion 8 driven gear 8
9 Rack 10 Motor 11 Drive gear 12 Guide member 13 Spring receiving member 14 Spring 15 Stopper

Claims (3)

Along with supporting the pinion, the pinion is swingably supported by a support shaft parallel to the center axis of the pinion, and when the pinion is brought into contact with a rack, a line connecting the support shaft and the shaft of the pinion is formed by the line. A swing arm arranged at a predetermined angle to a surface perpendicular to the axis of the rack,
A spring element for urging the swing arm so that the rack is pressurized by the pinion;
A rack and pinion mechanism comprising: A drive gear whose axis is located on an extension of the axis of the support shaft of the swing arm, and a driven gear attached to the shaft of the pinion and meshing with the drive gear are further provided.
The rack and pinion mechanism according to claim 1, wherein power of the driving gear is transmitted to the pinion via the driven gear. The rack and pinion mechanism according to claim 1 or 2, further comprising an arm stopping means for stopping swing of the swing arm before the pinion and the rack are disengaged from each other.

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