JP4056614B2 - Parallel shaft gear reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a parallel shaft gear reducer configured to distribute rotational torque of an input shaft to two systems, and to merge and transmit the distributed rotational torque to an output shaft at the same time.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various proposals have been made for methods and devices for transmitting rotational torque from an input shaft to an output shaft in a parallel shaft gear reducer in which an input shaft and an output shaft are incorporated in parallel.
[0003]
5 (a) and 5 (b) show conventionally known parallel shaft gear reducers R1 and R2.
[0004]
First, (a) of FIG. 5 will be described.
[0005]
The parallel shaft gear reducer R1 includes an input shaft 2 that receives rotation from a motor (not shown), and an output shaft (fourth shaft) 4 that outputs the finally reduced rotation.
[0006]
In this parallel shaft gear reducer R1, when rotational torque is input to the input shaft 2, the rotation is first transmitted to the second gear 10 that meshes with the first gear 20, and the second gear 10 is further incorporated. Is transmitted to the fourth gear 14 meshing with the third gear 12 via the third gear 12 on the gear shaft (second shaft) 6. Then, the fifth gear 16 of the same gear shaft (third shaft) 8 as that of the fourth gear 14 is transmitted to the sixth gear 22 meshing therewith, and finally transmitted to the output shaft 4.
[0007]
The parallel shaft gear reducer R2 in FIG. 5B has a hollow shaft 5 as an output shaft, but the basic structure is substantially the same as that in FIG.
[0008]
The parallel shaft gear reducers R1 and R2 have a structure in which one gear meshes with one gear. Therefore, when a large rotational torque (high load) is to be transmitted, the respective shafts are thickened. Furthermore, it is necessary to enlarge each gear (first to sixth gears). However, according to the needs of consumers, it is often used especially in a limited installation space. In this case, it is difficult to enlarge each shaft and each gear. That is, when a small size and high performance are desired, it is necessary to shorten the axial distance between the input shaft 2 and the output shaft 4 (5) and to withstand a high load.
[0009]
Therefore, a planetary gear speed reducer having a speed reducing portion as shown in FIG. 6 is used as a typical speed reducer in which a plurality of gears mesh with one gear to distribute rotational torque and transmit it to the output shaft. R3 is known. This planetary gear reducer R3 has a plurality of planetary gears 26 around the sun pinion 24, and can increase the rotational torque (load) transmission capacity relatively easily.
[0010]
[Problems to be solved by the invention]
However, as is well known, the planetary gear reducer R3 having the speed reduction unit as shown in FIG. 6 has a concentric input shaft and output shaft (not shown). When it is desired to transmit to the end, a separate parallel axis reduction unit is required, resulting in a complicated structure and an increased cost.
[0011]
For this reason, the parallel shaft gear reduction is configured such that the rotational torque of the input shaft is received by, for example, two pairs of gears and distributed to separate systems (first shaft and second shaft) and merged and transmitted to the output shaft. One way to achieve this is by the machine itself.
[0012]
That is, two gears of the first gear and the second gear are incorporated in the input shaft, while two shafts of the first shaft and the second shaft are provided in parallel with the input shaft, and the third and fourth gears are provided on the two shafts. Assemble and mesh with the first and second gears, respectively. As a result, the rotational torque that has entered the input shaft is distributed to the first gear → third gear (first shaft) system and the second gear → fourth gear (second shaft) system. The rotational torque distributed to the first shaft and the second shaft is caused by the meshing between the fifth and sixth gears incorporated on the first shaft and the second shaft, respectively, and the output shaft gear incorporated on the output shaft. Are simultaneously merged and transmitted on the output shaft.
[0013]
However, when the speed reduction structure having such a configuration is adopted, especially if the strengths at which the fifth and sixth gears mesh with the output shaft gears are slightly different due to built-in errors, etc., the rotational torque distributed to the respective systems When (load distribution) is not uniform and is severe, power is transmitted only to the system on one side, and the system on the other side is just turning within the range of the backlash of each gear. Sometimes it ends up.
[0014]
Thus, if the transmission torque from each gear to the output shaft gear (hereinafter referred to as meshing strength) is different, naturally, only the burden on the gear that meshes most strongly with the output shaft gear is increased. As a result, not only is the wear of the gear increased, but the allowable transmission capacity of the entire reduction gear cannot achieve the original capacity (two systems).
[0015]
In addition, the gears are intricately engaged with each other and are rotating at a high speed and with a high load. The reality is that it is actually difficult to eliminate the inequality.
[0016]
Even if the unevenness of load distribution is eliminated to some extent by securing rigidity of each gear and shaft, improving machining accuracy and assembly accuracy, or selecting and assembling parts during assembly, etc. Inequality often occurred again.
[0017]
The present invention has been made in view of such conventional problems, and is basically based on a parallel shaft gear reducer with a simple structure, and distributes rotational torque of an input shaft to a plurality of systems. While adopting a configuration to transmit and finally merge and transmit to the output shaft, the transmission capacity (load distribution) in each system is automatically equalized, each gear of each system performs power transmission evenly, Accordingly, it is an object of the present invention to provide a parallel shaft gear reducer that can ensure a high transmission capacity in the entire reducer without forming an overload state on only some of the gears.
[0018]
[Means for Solving the Problems]
The present invention includes an input shaft, an output shaft incorporated in parallel with the input shaft, a first gear and a second gear having the input shaft as a gear shaft, and a gear of a third gear meshing with the first gear. A first shaft parallel to the input shaft, and a gear shaft of a fourth gear meshing with the second gear, the second shaft parallel to the input shaft, and In the parallel shaft gear reducer configured to simultaneously transmit the rotation of the shaft and the second shaft to the output shaft, a helical gear is used for the first to fourth gears, and the input shaft is The first gear and the second gear are assembled with the direction of helical twisting reversed, and the third gear and the fourth gear are assembled to the respective gear shafts so as to mesh with the first gear and the second gear, respectively. , The axial relative position of the first gear and the third gear, or the axis of the second gear and the fourth gear. And it can be displaced at least one of the relative position of the direction, and, among the third gear and the fourth gear, at least one, by which is slidable in the first axis or on the second shaft, solving the above problems It is a thing.
[0019]
In the present invention, as a specific gear structure for transmitting the rotation of the first shaft and the second shaft to the output shaft at the same time, this may be a spur gear, or a helical gear. You may comprise.
[0020]
According to the present invention, by making at least one of the third gear and the fourth gear slidable in the axial direction, it is possible to prevent an excessive thrust force from being applied to only some of the bearings.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0022]
FIG. 1 is a plan view schematically showing a meshing structure of a parallel shaft gear reducer according to a technique (referred to as a base technique) serving as a base of the present invention. FIG. 2 is an arrow II view of FIG. 1 viewed from the right side of the drawing. 3 is a perspective view seen from the right front side of the paper surface of FIG. 1 in order to easily show the state of twisting of the helical gear in part III of FIG.
[0023]
First, for convenience, the base technology will be described with reference to FIG.
[0024]
This parallel shaft gear reducer includes an input shaft 102, an output shaft 104 incorporated in parallel with the input shaft 102, a first gear 106 and a second gear 108 having the input shaft 102 as a gear shaft, and a first gear. 106 is a gear shaft of a third gear 114 that meshes with the first gear 110, and is a gear shaft of a fourth gear 118 that meshes with the second gear 108 and parallel to the input shaft 102. A second shaft 112.
[0025]
A fifth gear 116 and a sixth gear 120 are incorporated in the first shaft 110 and the second shaft 112, respectively. Further, the output shaft 104 incorporates a seventh gear (output shaft gear) 122 that meshes simultaneously with the fifth gear 116 and the sixth gear 120 (which is the final gear).
[0026]
That is, in this parallel shaft gear reducer, the rotational torque input to the input shaft 102 is the first system L1 of the first gear 106 → the third gear 114 → the first shaft 110 → the fifth gear 116, and the second gear. 108 → the fourth gear 118 → the second shaft 112 → the sixth gear 120 is distributed and transmitted to the second system L2, and the fifth gear 116 of the first system L1 and the sixth gear 120 of the second system L2 are (1 The rotation torques transmitted in a distributed manner are joined and transmitted to the output shaft 104 by meshing at positions P 1 and P 2 different from the output shaft gear 122.
[0027]
Here, in this base technology , helical gears are used for the first to seventh gears, and the first gear 106 and the second gear 108 are assembled so that the directions of twisting are opposite to each other when viewed from the plane. It is. That is, the direction of the helical gear of the set of the first gear 106 and the third gear 114 and the direction of the helical gear of the set of the second gear 108 and the fourth gear 118 with respect to the input shaft 102. Are set to be opposite to each other when viewed from the plane. Note that the helical torsion angles θ of the first gear 106 and the second gear 108 are set to be the same.
[0028]
The input shaft 102, the output shaft 104, the first shaft 110, and the second shaft 112 are each supported by a bearing (not shown) so as to be rotatable. The structure is such that it cannot slide in the axial direction, and only the input shaft 102 is slidable in the axial direction. The structure that allows the input shaft 102 to slide in the axial direction is not particularly limited, and a known bearing structure can be appropriately employed.
[0029]
As shown in FIGS. 1 and 3, the fifth gear 116 and the sixth gear 120 mesh with the seventh gear (output shaft gear) 122 at the same time. .
[0030]
Next, the operation of this base technology will be described.
[0031]
When the torque that the fifth gear 116 and the seventh gear 122 mesh is T1, and the torque that the sixth gear 120 and the seventh gear 122 mesh is T2, the total torque that the seventh gear 122 receives is T. The following equation holds.
[0032]
T = T1 + T2 (1)
[0033]
Here, T1 corresponds to the torque transmitted to the seventh gear 122 via the first system L1, and T2 corresponds to the torque transmitted to the seventh gear 122 via the second system L2. Needless to say, it is ideal that the rotational torque from the input shaft 102 is distributed by 1/2 to each of the systems L1 and L2, but as described above, if there is a gear machining error or an assembly error, There is a situation in which a distribution of 1/2 (equal) is not necessarily realized, and only one of them becomes larger. In this case, since the total torque T received by the seventh gear 122 is not changed, one of the two ends up in an overload state because one of them is reduced.
[0034]
When the torque transmitted from the input shaft 102 to the first gear 106 is t1, the torque transmitted to the second gear 108 is t2, and the total is t, the following equation is naturally established.
[0035]
T / t = constant (2)
T1 / t1 = T2 / t2 = constant (3)
[0036]
Here, it is assumed that the transmission torque of the first system L1 becomes larger due to the variation in the meshing strength, and T1> T2. In this case, the relationship of t1> t2 is naturally established by the above relationships.
[0037]
On the other hand, when power is transmitted by the meshing of the helical gear, an axial component proportional to the transmitted torque is generated at the meshing point in accordance with the torsion angle (tilt) θ of the helical gear. In the case of the first embodiment, in the first system L1, since the output shaft 104 and the first shaft 110 are fixed in the axial direction, the input shaft 102 is caused to react in the direction of the arrow by the reaction of the axial component force. X receives a moving force F1.
[0038]
Similarly, the input shaft 102 receives a moving force F2 in the direction of the arrow Y in the figure due to the reaction of the axial component force generated during power transmission between the input shaft 102 and the second gear 108. Since the helical twist angle θ is set to be the same between the first gear 106 and the second gear 108, the moving force F1 is proportional to the transmission torque t1, and the moving force F2 is proportional to the transmission torque t2. Therefore, if t1> t2, F1> F2, and the input shaft 102 moves (slides) in the direction of the arrow X by the moving force F1.
[0039]
When the input shaft 102 moves in the direction of the arrow X of the moving force F1, since the third gear 114 is fixed in the axial direction, the meshing (strength) between the first gear 106 and the third gear 114 is that much. It will be relaxed. When the meshing is loosened, naturally the torque t1 transmitted there is also weakened. On the other hand, on the second system L2 side, the input shaft 102 moves in the direction of the arrow X of the moving force F1, whereby the meshing between the second gear 108 and the fourth gear 118 is strengthened, and the transmission torque t2 here is Increase. That is, as a result, when the moving force F1 is weakened, the moving force F2 is relatively strengthened, so that the input shaft 102 is at a position where the moving forces F1 and F2 are exactly equal, that is, a position where t1 and t2 are equal. It will automatically converge to (position where T1 and T2 are equal).
[0040]
When the transmission force t2 on the second system L2 side becomes larger, F2> F1, so that the movement is completely symmetrical with the above-described action, and again F1 = F2 (t1 = t2, T1). = T2).
[0041]
In this way, when one of the fifth gear 116 and the sixth gear 120 meshes with the seventh gear (output shaft gear) 122, the transmission torque T1 or T2 becomes larger than the other T2 or T1. Then, the input shaft 102 slides and finally slides to a position where T1 = T2 and always becomes stable.
[0042]
Regarding the so-called hunting phenomenon in which the fifth gear 116 and the sixth gear 120 mesh with the seventh gear 122, the meshing force becomes stronger or weaker. Since friction always exists, the sliding resistance of the input shaft 102 can be set within a range without any trouble by setting the sliding resistance of the input shaft 102 appropriately with respect to the total transmission force.
[0043]
As a result, the first system L1 and the second system L2 result in the transmission torques t1, t2, or T1, T2 being evenly distributed, and the gears of the systems L1, L2 are equally loaded. The durability of the gear can be improved, and power loss and noise due to friction can be minimized.
[0044]
In this base technology , all the gears are constituted by helical gears. However, the fifth to seventh gears do not need to be helical gears. For example, a spur gear can obtain the same effect. It is done.
[0045]
Next, a description will be given implementation of the invention.
[0046]
This embodiment basically has the same configuration as the base technology (all gears are helical gears), but the structure of the first shaft is improved in order to reduce the load on the bearing of the third gear. It is.
[0047]
That is, when all the gears are constituted by helical gears, in the first system, the fifth gear 116 and the seventh gear 122 are engaged with each other on the first shaft 110 due to the relationship of the helical direction. Direction of the generated axial component force F3 and the axial component force F4 generated on the first shaft 110 by meshing with the first gear 106 and the third gear 114 (the same direction as F1 but opposite in direction) Therefore, a very large load in the thrust direction is applied to the bearing 200 of the third gear 114.
[0048]
Therefore, as shown in FIG. 4, the bearing 206 is sandwiched between the step portion 212 of the first shaft 210 and the plate 202 fixed to the first shaft 210 by the bolt 204, and the bearing 206 is received by the step portion 208 on the housing side. Thus, the axial component F3 generated on the first shaft 210 due to the engagement of the fifth gear 116 and the seventh gear 122 is prevented from being applied to the bearing 200.
[0049]
That is, since the third gear 114 is incorporated on the first shaft 210 via the spline 216, the third gear 114 has an axial component generated by the meshing of the third gear 114 and the first gear 106. Only the force F4 is applied, and only the component force F4 needs to be received by the bearing 200. As a result, in the previous base technology (because no countermeasure was taken), the axial component force F3 generated by the engagement of the fifth gear 116 and the seventh gear 122 in the bearing on the third gear side, and the first gear 106 And the axial component force F4 generated by the meshing with the third gear 114, while only the latter F4 is applied, the load is reduced accordingly.
[0050]
Note that the direction of the thrust load applied from the fourth gear 118 and the direction of the thrust load applied from the sixth gear 120 are reversed on the second system L2 side depending on the direction of twisting of the helical gear. A large thrust load is not generated. Therefore, the second system L2 does not need to take a countermeasure as in the present embodiment, but does not specifically prohibit the same configuration.
[0051]
【The invention's effect】
As described above, according to the present invention, the rotational torque (meshing strength) from each gear meshed with the final gear (output shaft gear) incorporated in the output shaft is automatically equalized. Therefore, the transmission permissible ability inherent to each gear can be fully exhibited without imposing a burden on one specific gear, and as a result, reduction in size and weight can be realized.
[Brief description of the drawings]
[1] Seventh gear in the arrow II plan view [FIG 3] The base technology schematic plan view showing a meshing structure of the gear and the shaft of the parallel shaft gear reducer according to the base technology [2] Figure 1 (output shaft gear) and the fifth gear meshes with it, cross-sectional view and FIG. 5 conventional parallel axis showing the support structure of the first near the axis of the implementation form of the sixth perspective view of the gear 4 shows the present invention FIG. 6 is a sectional view showing a gear reducer. FIG. 6 is a sectional view showing a conventionally known planetary gear reducer.
102: input shaft 104 ... output shaft 106 ... first gear 108 ... second gear 114 ... third gear 118 ... fourth gear 116 ... fifth gear 120 ... sixth gear 122 ... seventh gear (output shaft gear)
110 ... first axis 112 ... second axis

Claims (3)

A gear shaft of an input shaft, an output shaft incorporated in parallel with the input shaft, a first gear and a second gear having the input shaft as a gear shaft, and a third gear meshing with the first gear; A first axis parallel to the input axis;
A gear shaft of a fourth gear meshing with the second gear, wherein the second shaft is parallel to the input shaft, and the rotation of the first shaft and the second shaft is simultaneously transmitted to the output shaft. In the parallel shaft gear reducer configured as described above,
A helical gear is used for the first to fourth gears,
The first gear and the second gear are incorporated in the input shaft so that the helical twist directions are reversed, and the third gear and the fourth gear are engaged with the first gear and the second gear, respectively. Built into each gear shaft,
Wherein the first gear and the relative axial position between the third gear, or to be displaced at least one of the axial relative position between the second gear and the fourth gear,
In addition, at least one of the third gear and the fourth gear can be slid on the first shaft or the second shaft.
A parallel shaft gear reducer characterized by that. In claim 1,
A spur gear incorporated in each of the first shaft and the second shaft and meshing with the output shaft is used as a gear configuration for transmitting the rotation of the first shaft and the second shaft to the output shaft at the same time. A parallel shaft gear reducer. Oite to claim 1,
As a gear structure for transmitting the rotation of the first shaft and the second shaft to the output shaft at the same time, a helical gear that is incorporated in the first shaft and the second shaft and meshes with the output shaft is used. A parallel shaft gear reducer.

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