JP2001200909A - Power transmitting gear for reduction gear and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a problem that a gear can not be smoothly rotated because of a dimensional change with the water absorbing work and a change of the degree of crystallization in a power transmitting gear made of the polyamide resin. SOLUTION: This power transmitting gear is made of the synthetic resin including polybutylene terephtharate(PBT) and the resin material including the reinforcing material made of the glass fiber. Since the PBT is hard to absorb the water and hard to generate a change of degree of crystallization, dimensional change of the gear because of the water absorption and a change of degree of crystallization can be restricted. Deformation of the gear when applying a load is restricted by the reinforcing material. In the case of including the solid lubricating agent in the resin material, absorption of the gear can be restricted. As a result, play of a reduction gear can be maintained at the minimum, and looseness can be always prevented so as to smoothly rotate the gear. The gear has gear teeth provided in the peripheral surface and a female screw in the through hole, and the gear is used for a reduction gear 8 for adjusting position of a steering shaft 3 of a steering device 1 for automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission gear (hereinafter simply referred to as "gear") for a speed reducer. For example, the present invention relates to a gear of a speed reducer for adjusting a position of a steering shaft using a motor in a steering apparatus of an automobile.

[0002]

2. Description of the Related Art Some of the above-mentioned gears are formed of a synthetic resin such as polyamide in order to reduce the operating noise of a speed reducer. However, the dimensions of gears made of polyamide can vary. This is because polyamide tends to have a water-absorbing effect, and the dimensions of the gear may be changed by absorbing water in the atmosphere. Further, in the case of polyamide, the degree of crystallinity tends to change with the passage of time, so that the gear size may change with the change in degree of crystallinity. As a result, play between gear teeth may be reduced.

Incidentally, in the above-described speed reducer for a steering device, it is preferable to keep play between gear teeth to a minimum so as to prevent rattling and to allow the gears to rotate smoothly. In the case where the above-mentioned polyamide gear is used in such a device, for example, if the play at the time of assembly is minimized, the play further decreases with time as described above, and as a result, the gear becomes excessively small. There is a risk that the gears may bite and the gear may not rotate smoothly.

In order to ensure smooth rotation,
It is conceivable to make the play sufficiently large at the time of assembling in anticipation of the above-mentioned dimensional change due to a change in water absorption or crystallinity, but this is not practical because rattling may occur. Therefore, an object of the present invention is to solve the above-mentioned technical problem, and to provide a power transmission gear for a speed reducer that can always prevent rattling and can rotate smoothly, and a steering device using the same.

[0005]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, at least a part of the resin material is made of polybutylene terephthalate,
A power transmission gear for a speed reducer, comprising at least one synthetic resin of polyethylene terephthalate and polyphenylene sulfide. According to the present invention, since the above-mentioned synthetic resin hardly causes a change in the water absorbing action and the degree of crystallinity, the dimensional change of the gear accompanying these can be suppressed. As a result, the play between the gear teeth can be kept to a minimum, so that the gears can always mesh and rotate smoothly without play.

Here, as the power transmission gear, an external gear,
In addition to various gears constituting a gear mechanism such as an internal gear and a rack,
It also includes a screw member having a female screw or a male screw that constitutes a screw mechanism. According to a second aspect of the present invention, in the power transmission gear for a speed reducer according to the first aspect, the resin material includes:
A power transmission gear for a speed reducer, characterized by containing a reinforcing material having a content ratio of about 55% by weight.

According to the present invention, since the reinforcing material can increase the strength of the resin material, the deformation of the gear due to the load can also be suppressed, so that the play between the gear teeth can be surely kept to a minimum. Here, as the reinforcing material, for example, glass fiber,
Carbon fiber or the like can be used, and the content of the reinforcing material in the resin material may be in the range of 0 to 55% by weight. That is, when the reinforcing material is not included, the strength of the resin material may not be sufficiently obtained. Further, when the content ratio of the reinforcing material exceeds 55% by weight, it becomes difficult to mold the resin material.

According to a third aspect of the present invention, in the power transmission gear for a speed reducer according to the first or second aspect, the resin material contains a solid lubricant having a content of 0 to 15% by weight. A power transmission gear for a speed reducer, wherein According to the present invention, the solid lubricant can reduce the resistance at the time of gear engagement by its lubricating action, so that the gear can be rotated more smoothly. Further, since the solid lubricant can enhance the wear resistance of the resin material, the wear of the gear due to the load can be suppressed, and as a result, the play between the gear teeth can be reliably kept to a minimum. Here, as the solid lubricant, for example, polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS ₂ )
Etc., and the solid lubricant may be contained in the resin material at a content of 0 to 15% by weight. This is because when no solid lubricant is contained, the frictional resistance may increase. If the content of the solid lubricant exceeds 15% by weight, the strength of the resin material may be reduced.

According to a fourth aspect of the present invention, there is provided a steering apparatus having a speed reducer for transmitting a driving force of a motor for adjusting a position of a steering shaft, wherein the speed reducer is any one of the first to third aspects. A steering device comprising the power transmission gear according to any one of (1) to (4). According to the present invention, the play of the gear teeth of the speed reducer can be kept to a minimum by the gears described above, so that it is possible to prevent rattling during steering operation of the steering device and to ensure a smooth adjustment operation of the steering shaft, In addition, the operation sound during the adjustment operation can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a steering device according to an embodiment of the present invention will be described. FIG. 1 is a front view of the steering device. The steering device 1 has a steering shaft 3 that is inserted inside a tubular steering column 2 and is rotatably supported. The upper end 31 of the steering shaft 3 (the right end in FIG. 1)
Is connected to a steering wheel (not shown), and the lower end 32 (which is the left end in FIG. 1) of the steering shaft 3 is connected to a steering gear (not shown). By transmitting the movement of the steering wheel to the steering gear via the steering shaft 3, wheels (not shown) are steered.

The steering shaft 3 includes a lower shaft 3
3, the upper end of the lower shaft 33 and the universal joint mechanism 34
, And an upper shaft 37 connected to the middle shaft 35 via a spline structure 36. Upper shaft 37 and middle shaft 3
Reference numeral 5 indicates a relative displacement in the axial direction. The steering column 2 includes a lower column 21 that rotatably supports a lower shaft 33 via a bearing (not shown),
Brackets 22 and 23 for fixing the vehicle to a predetermined portion of the vehicle body
And an upper column 25 rotatably connected to the upper end of the lower column 21 and an upper column 25 slidably engaged with the upper portion of the middle column 24 in the axial direction. The upper column 25 rotatably supports the upper shaft 37 of the steering shaft 3 via a bearing (not shown). The upper column 25 is formed in a cylindrical shape, and its inner peripheral surface is
The middle column 24 is fitted on the outer peripheral surface of the cylindrical upper part. The middle column 24 is rotatable around a tilt center axis (the position C of the center axis is shown) with respect to the lower column 21. The tilt center axis extends in a direction perpendicular to the direction in which the lower shaft 33 extends, and the steering device 1 is mounted on the vehicle body such that this direction is horizontal.

The steering device 1 has a lower portion 12 including a lower column 21 and a lower shaft 33, and an upper portion 11 including an upper column 25 and an upper shaft 37. The upper portion 11 is rotatable about the tilt center axis with respect to the lower portion 12, and the upper shaft 37 is movable with respect to the lower portion 12.
Can be linearly displaced along the extending direction (extending and contracting direction). A tilt mechanism 4 for rotating and displacing the upper part 11 with respect to the lower part 12 using the motor 7 and an upper part 1 using the motor 7 are provided at an intermediate portion of the steering device 1.
Telescopic mechanism 5 for linearly displacing 1 with respect to lower part 12
Are provided.

The tilt mechanism 4 and the telescopic mechanism 5 each have a drive unit 6 that is configured in substantially the same manner.
The drive unit 6 includes the motor 7 and the speed reducer 8 described above. The speed reducer 8 is configured so that the rotating shaft of the motor 7 does not rotate in response to a reverse input from the output side, and also serves as a lock mechanism that regulates the position of the steering shaft 3. When the motor 7 is driven, the end of the screw shaft 42 serving as the output unit of the drive unit 6 advances and retreats.
The end of the screw shaft 42 of the drive unit 6 of the tilt mechanism 4
It is connected to an operation arm 26 provided on the middle column 24,
Due to the displacement of the screw shaft 42 accompanying the rotation of the motor 7, the middle column 24, and thus the upper part 11, rotates around the tilt center axis via the operation arm 26. The end of the screw shaft 42 of the drive unit 6 of the telescopic mechanism 5 is connected to the operation arm 27 of the upper column 25, and the upper column 25 and, by extension, the upper part 11 are slid in the telescopic direction by the displacement of the motor 7. I do. As described above, the position of the steering wheel can be easily adjusted according to the driver by using the driving force of the motor 7.

FIG. 2 is a partial sectional view of the drive unit. The speed reducer 8 includes, as two sets of power transmission gears, a set of a worm gear 40 and a worm wheel 41, and a nut 43.
And a screw shaft 42. Worm gear 40
And the worm wheel 41 constitute a reduction gear mechanism. The nut 43 and the screw shaft 42 constitute a screw mechanism,
Converts rotational displacement to linear displacement. With these screw mechanism and gear mechanism, two-stage speed reduction is performed. The worm gear 40 is provided so as to be able to rotate integrally with the rotation shaft of the motor 7. The worm wheel 41 has a plurality of gear teeth 45 on the outer peripheral surface.
0 meshes with the gear teeth. Also, the worm wheel 41
Is integrally formed so as to be integrally rotatable with the nut 43 described above, has a through hole concentric with the rotation center axis thereof, and a female screw 46 of the nut 43 is formed in this through hole. A male screw 47 formed on the outer peripheral surface of the screw shaft 42
Are screw-engaged. The male screw 47 and the female screw 46 are, for example, trapezoidal screws.

The worm gear 40 and the screw shaft 42 are made of steel. The worm wheel 41 is entirely formed of the following resin material. As a result, the dimensional stability of the gear is enhanced, and the amount of dimensional change over time after molding can be reduced. The resin material includes a synthetic resin made of polybutylene terephthalate (PBT) as a base resin and a reinforcing material made of glass fiber. Further, the resin material may include a solid lubricant.

As the base resin, besides PBT, polyphenylene sulfide (PPS), polyethylene terephthalate (PET) or the like can be used as described later. The content ratio of the reinforcing material is in the range of 20 to 30% by weight. As described above, according to the present embodiment, since the synthetic resin containing PBT is unlikely to cause a change in the water absorption function and the degree of crystallinity, the dimensional change of the gear made of the resin material due to these can be suppressed. As a result, the play between the gear teeth can be kept to a minimum, so that the gears can always mesh and rotate smoothly without play.

More specifically, synthetic resins such as PBT have a smaller water absorption than polyamide (PA), and the dimensional change upon water absorption is extremely small. Therefore, PBT and the like can reduce the amount of dimensional change associated with the absorption of moisture in the atmosphere, as compared with PA. In addition to this, PBT and the like also have a change in crystallinity (difference between crystallinity immediately after molding and crystallinity in a stable state after a sufficient time has elapsed) compared to PA. It is small, and the amount of dimensional change accompanying a change in crystallinity can be reduced. As a result, the PBT can make the variation in the dimensional change of the gear smaller than that of the PA with respect to the elapsed time and each gear.

Here, if at least a part of the gear is made of the above-mentioned resin material, the above-mentioned effect can be obtained. However, if the entire gear is made of the above-mentioned resin material, the effect can be surely obtained. Is preferred. Further, the synthetic resin capable of obtaining the above-described effects can be a resin that does not easily cause a change in water absorption and crystallinity, and the magnitude of the crystallinity is not a problem, and the amount of change in crystallinity is small. Is preferred.
Examples of the synthetic resin include PBT, PET, PPS and the like. These synthetic resins may be used alone or in combination of two or more. In short, it is sufficient that the resin material contains at least one of these synthetic resins. Further, the resin material does not have to include one or both of the reinforcing material and the solid lubricant, but the following effects can be obtained by the reinforcing material and the solid lubricant.

Since the reinforcing material can increase the strength of the resin material, the bending deformation of the gear teeth caused by the load can be suppressed, so that the play between the gear teeth can be surely kept to a minimum. Here, as the reinforcing material, for example, in addition to glass fiber (GF), carbon fiber (CF), glass beads (GB), aramid fiber (AF), and the like can be used alone or in combination of two or more. The content ratio of the reinforcing material used is appropriately determined according to the specifications such as the strength of the gear, but the content ratio of the reinforcing material in the resin material may be within the range of 0 to 55% by weight. That is, when the reinforcing material is not included, the strength of the resin material may not be sufficiently obtained. Further, when the content ratio of the reinforcing material exceeds 55% by weight, it becomes difficult to mold the resin material.

In particular, when the content ratio of the reinforcing material is in the range of 20 to 30% by weight, it is preferable to obtain sufficient strength while preventing abrasion of the mating member. Further, if the reinforcing material is glass fiber, it is preferable to reduce the material cost. Further, when the reinforcing material contains glass beads, it is preferable to suppress warpage at the time of molding while increasing the strength as compared with the case where only the fibrous reinforcing material is used. When the resin material contains a solid lubricant, the lubricating action of the solid lubricant can reduce the resistance at the time of gear engagement, so that the gear can be rotated more smoothly. Further, since the solid lubricant can enhance the wear resistance of the resin material, the wear of the gear due to the load can be suppressed, and as a result, the play between the gear teeth can be reliably kept to a minimum. Here, the solid lubricant may be contained in the resin material at a content ratio in the range of 0 to 15% by weight. This is because when no solid lubricant is contained, the frictional resistance may increase. If the content of the solid lubricant exceeds 15% by weight, the strength of the resin material may be reduced.

Examples of the solid lubricant include polytetrafluoroethylene (PTFE) and molybdenum disulfide (M
oS ₂ ) can be used. These solid lubricants may be used alone or in combination of two or more. The content ratio of the solid lubricant to be used is appropriately determined according to the specifications of the gear, but differs depending on the type of the solid lubricant.
The content of PTFE is in the range of 5 to 10% by weight,
The content of MoS ₂ is preferably in the range of ₂ to 5% by weight from the viewpoint that a lubricating action can be obtained and the strength of the resin material does not decrease, and both PTFE and MoS ₂ are contained in the resin material. You may.

In particular, when the resin material contains both the reinforcing material and the solid lubricant, it is preferable because the play between the gear teeth can be more reliably maintained to a minimum. When the gear made of the resin material described above is applied to the tilt mechanism 4 for adjusting the position of the steering shaft 3 of the steering device 1 and the speed reducer 8 of the telescopic mechanism 5, the gears described above are used.
Since the play of the gear teeth can be kept to a minimum, it is possible to prevent rattling at the time of the steering operation of the steering device 1, to secure a smooth adjustment operation of the steering shaft 3, and to reduce the operation sound at the time of the adjustment operation. In particular, in a steering device that uses the driving force of a motor for position adjustment, the reduction gear usually also serves as a lock mechanism, and the rattling of the reduction gear is directly linked to the rattling during the steering operation. The gear of the present invention is preferred for preventing sticking.

In addition, a power transmission gear having at least a meshing portion made of resin can reduce, for example, the meshing noise of gear teeth during power transmission as compared with a case where power is transmitted through metal members. In addition, since rattling can be prevented, rattling noise of gear teeth due to rattling can also be prevented. In particular, PBT, PET and PPS have the following advantages: excellent wear resistance, low coefficient of friction, excellent chemical resistance to grease and the like, and excellent economic efficiency. preferable.

Since the synthetic resin containing PBT has a small change in the degree of crystallinity, the process for reducing the change in the degree of crystallinity to a practically acceptable level can be simplified. For example, the processing time of the annealing process can be reduced. Here, the annealing process is a process of maintaining the article to be processed at a predetermined processing temperature for a predetermined processing time and then naturally cooling it at room temperature, and is performed for removing distortion after molding. For example, when annealing is performed so that the amount of change in crystallinity is reduced to a level at which there is no practical problem, P
Comparing the A product and the PBT product,
In the case of a PA product, a processing temperature of 130 ° C. and a corresponding processing time of 24 hours are required. On the other hand, in the case of the PBT product, the processing temperature is 130 ° C.
And the processing time is only four hours, and the processing time is much shorter. Alternatively, in the case of a PBT workpiece, the processing time is set to 2
The treatment temperature may be lowered to 120 ° C. for 4 hours. Therefore, the processing cost can be reduced.

In the above-described embodiment, the worm wheel 41 integrated with the nut 43 is made of a resin material including PBT, but is not limited to this. For example, the nut 43 and the worm wheel 41 may be formed separately, and only the nut 43 may be made of the resin material described above, or the worm wheel 41 alone. Further, the screw shaft 42 and the worm gear 40 may be made of the above-mentioned resin material. Further, the worm wheel 41, the worm gear 4
Gears other than 0 may be made of the above resin material. Thus, as the power transmission gear, in addition to various gears constituting a gear mechanism such as an external gear, an internal gear, and a rack, the power transmission gear also includes a screw member having a female screw or a male screw constituting a screw mechanism. The threads correspond to the gear teeth.

A gear made of a resin material containing PBT or the like can be used not only for the speed reducer 8 of the steering device 1 but also for a speed reducer of a general industrial machine. In addition, various design changes can be made without changing the gist of the present invention.

[0027]

EXAMPLES is an example and the comparative example base resin PBT, added in the proportion of 30% by weight of glass fibers as reinforcement, after the preparation of the molding resin material is kneaded, the molding resin material It was molded to obtain the gear of the example. Further, a glass resin having a content of 25% by weight was added to polyamide 66 (PA66), which is a base resin, and kneaded to prepare a molding resin. Then, the molding resin was molded to obtain a gear of a comparative example. Was. The gears of the example and the comparative example correspond to the worm wheel 4 of the above-described embodiment.
It is one.

Test 1 With respect to the resin materials for molding used in Examples and Comparative Examples, a change in crystallinity over time was tested.
In the test method, the crystallinity of the resin material of the test article was measured together with the elapsed time immediately after molding, while maintaining the test article at a predetermined test temperature, for example, 85 ° C. The crystallinity was measured, for example, as follows. That is, when the density of the sample is measured, the crystallinity A (%) of the sample can be obtained from the following equation.

A = [Dc (D-Da)] / [D (Dc-Da)] where Dc is the density of the crystal phase (g / cm ³ ), and Da is the density of the amorphous phase.
(g / cm ³ ) and D is the density of the sample (g / cm ³ ). As the test article, the gears of the examples and comparative examples were used in a state where they were just molded, and were not subjected to annealing treatment. Further, the test temperature of 85 degrees is the maximum use temperature assumed for the above-described gear.

As a result of the test, the results shown in the graph of FIG. 3 were obtained. FIG. 3 shows the crystallinity for an elapsed time of up to 200 hours.
It is shown by a circle indicating the measured value and a straight line connecting
As for the crystallinity after 0 hours, the tendency of the change is indicated by an arrow. According to this result, the PBT of the embodiment
For, the crystallinity is almost stable at 100 hours elapsed time. On the other hand, the crystallinity of the PA of the comparative example continued to increase and was not stable even after 200 hours. Furthermore, the trend of subsequent changes is also on the rise.

The change in the crystallinity of the PBT of the example (the difference between the crystallinity immediately after molding and the crystallinity after 200 hours) is the change in the crystallinity of the PA of the comparative example. Less than. Further, this tendency becomes even stronger when the tendency of the change in crystallinity after the elapsed time of 200 hours is considered. From these results, the amount of change in the degree of crystallinity of the example is much smaller than that of the comparative example. Moreover, the time required for stabilizing the crystallinity is also short. Therefore, practically, it is considered that in the embodiment, the change in crystallinity hardly occurs, and the dimensional change of the gear accompanying the change in crystallinity hardly occurs.

Test 2 For the molding resin materials used in the examples and comparative examples, the water absorption, the tensile strength, the bending strength,
Flexural modulus and friction torque were measured. The gears of the examples and comparative examples were annealed as described below to obtain test articles. The annealing was performed at a processing temperature of 120 ° C. and a processing time of 24 hours. (1) Water absorption rate The measuring method is based on ASTM D570. 2 items to be tested
The water absorption after holding in water for 4 hours was measured.

Measurement results. The water absorption of the comparative example is 0.8%. On the other hand, the water absorption of the example is 0.07%, which is much smaller than that of the comparative example, and hardly absorbs water. Further, since the polyamide resin of the comparative example usually absorbs moisture in the atmosphere, the water absorption is stabilized at an equilibrium state at a higher value (for example, 1.5 to 4%) than the above measured value. The difference in water absorption between the example and the comparative example is further increased.
Therefore, it is considered that the dimensional change due to water absorption in the example is extremely unlikely to occur as compared with the comparative example. (2) Tensile strength.

The measuring method is based on ASTM D638.
Measurement result. The tensile strength of the comparative example is 140 MPa. In contrast, the tensile strength of the example was 130 MP.
a, which is comparable to the comparative example. (3) Flexural strength The measuring method is based on ASTM D790. Measurement result. The flexural strength of the comparative example is 220 MPa. On the other hand, the bending strength of the example is 190 MPa, which is a level comparable to that of the comparative example. There is no practical problem. (4) Flexural modulus Measurement method is based on ASTM D790.

Measurement results. The flexural modulus of the comparative example is 8.0 G
Pa. In contrast, the flexural modulus of the example is 9.
5 GPa, which is higher in rigidity than the comparative example. Therefore, for example, the embodiment can reduce the amount of deformation of the gear teeth due to the load as compared with the comparative example, and is therefore preferable for keeping the play between the gear teeth to a minimum. (5) Friction torque A heat cycle test was performed on the test sample, and the friction torque of the actual machine was measured before and after the heat cycle test. The measuring method of the friction torque is as follows. That is, the gear of the DUT is incorporated in the speed reducer 8 of the telescopic mechanism 5 of the steering device 1, and the motor is reciprocated by a predetermined rotation angle, for example, approximately 8 rotations.
The torque was measured from the driving power of the motor during this time, and was determined as a friction torque. In the heat cycle test, a heat cycle at a low temperature of -40 ° C for 1 hour and then at a high temperature of 85 ° C for 1 hour was repeated 30 times. Here, the low temperature and the high temperature in the heat cycle test are the lower limit value and the upper limit value of the use environment temperature in the actual machine.

Measurement results. The friction torque of the comparative example was 0.004 to 0.02 Nm before the heat cycle test, and was 0.2 after the test.
15 to 0.26 Nm. The friction torque of the example was 0.005 to 0.02 Nm before the heat cycle test, and was 0.01 to 0.01 Nm after the test.
2 to 0.058 Nm. The friction torque before the test is almost the same as that of the example and the comparative example.However, the friction torque after the heat cycle test corresponding to a long time after the heat cycle test is much higher in the example than in the comparative example. small.
The difference in friction torque before and after the test, for example, when compared at the maximum value, increases about 10 times in the comparative example, but about 2.9 times in the example. Even if the friction torque increases by about 2.9 times, it is within a practically acceptable range, and there is no problem. Thus, it is considered that the embodiment can maintain the smooth rotation of the gear for a long period of time.

[Brief description of the drawings]

FIG. 1 is a front view of a steering device according to an embodiment of the present invention, in which a part of a steering shaft is schematically illustrated.

FIG. 2 is a partial sectional view of a speed reducer of the steering device of FIG.

FIG. 3 is a graph showing the change over time of the crystallinity of the resin material, in which the vertical axis shows the crystallinity (%), the horizontal axis shows the elapsed time (time), Comparative examples are indicated by black circles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering device 2 Steering shaft 7 Motor 8 Reduction gear 41 Worm wheel (power transmission gear)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihito Shibamura 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Koyo Seiko Co., Ltd. F-term (reference) 3D030 DD05 DD12 DD63 3J030 AC10 BA03 BC01

Claims (4)

[Claims] A power transmission gear for a speed reducer, wherein at least a part of the power transmission gear is made of a resin material, the resin material including at least one synthetic resin of polybutylene terephthalate, polyethylene terephthalate, and polyphenylene sulfide. . 2. The power transmission gear for a reduction gear according to claim 1, wherein the resin material contains a reinforcing material having a content ratio of 0 to 55% by weight. Power transmission gear for 3. The power transmission gear for a speed reducer according to claim 1, wherein the resin material contains 0 to 15% by weight.
A power transmission gear for a speed reducer, characterized by containing a solid lubricant having a content ratio of: 4. A steering apparatus provided with a speed reducer for transmitting a driving force of a motor for adjusting a position of a steering shaft, wherein the speed reducer is the above-mentioned speed reducer.
A steering device comprising the power transmission gear according to any one of the above.