JP4789279B2 - Motor shaft and micro motor for micro motor - Google Patents

Description

  The present invention relates to a motor shaft for a micro motor used as a drive source for various small devices, and a micro motor and a micro geared motor to which the motor shaft is applied.

Conventionally, a micromotor having an outer diameter of about several millimeters has been used as a drive source for a silent ringing vibration generator built in a mobile phone. In addition, this type of micromotor will be used as a driving source for various state-of-the-art devices such as medical devices (for example, a lens driving mechanism at the distal end of an endoscope and a driving mechanism for an intrauterine diagnostic treatment apparatus). The field of use is expected to expand further.
In general, when a micromotor is used in a small device such as a medical device, it is incorporated in the device as a micro geared motor coupled with a gear head having a reduction gear mechanism (for example, Patent Document 1).
Japanese Patent Laid-Open No. 2001-119894

  As shown in FIG. 6, the micro geared motor includes a motor unit 20 (micromotor) in which a pinion 23 is fixed to a motor shaft 22, and a reduction gear head that is drivingly connected to the motor unit 20 via the pinion 23. Part 21. The pinion 23 is fixed to the motor shaft 22 by press-fitting or bonding the motor shaft 22 into the mounting hole (center through hole). The reduction gear head portion 21 includes a reduction gear mechanism portion 24, and the pinion 23 meshes with the first gear 26, and the driving force of the motor shaft 22 passes through the reduction gear mechanism portion 24 to the output shaft 25. Reportedly.

  Depending on the device to which the micro geared motor is applied, a large reduction ratio by the reduction gear mechanism may be required. The reduction ratio is determined by the relationship between the number of gear teeth on the reduction gear mechanism side and the number of pinion teeth on the motor shaft side, and the more gear teeth on the reduction gear mechanism side, the more the number of pinion teeth. The smaller the ratio, the larger the reduction ratio can be obtained. However, since there is a restriction on the size (diameter) of the reduction gear head part, there is a limit to increasing the number of gear teeth on the reduction gear mechanism part side. In the micro geared motor, there is a limit to reducing the number of teeth by reducing the pinion diameter. For this reason, the conventional micro geared motor has a problem that a sufficiently large reduction ratio cannot be obtained.

In the conventional micromotor, the pinion is joined to the motor shaft by a method such as adhesion or press fitting. However, this joining structure has the following problems.
(a) Since a process for adhering or press-fitting an extremely small pinion and a motor shaft is required, not only will the cost be increased, but the joint may loosen due to repeated operation, causing problems such as pinion slip. is there.
(b) Because the joints are of extremely small size, it is difficult to ensure the coaxiality of the motor shaft and the pinion, and therefore a good meshing state between the pinion and the first gear on the reduction gear mechanism side cannot be obtained. There is a tendency to cause motor failure and noise generation.

  In addition, the pinion for the motor shaft of the micromotor is required to have high dimensional accuracy, high strength and high hardness in order to ensure excellent durability that is resistant to breakage and wear, Easy manufacturing is also an important factor. However, a conventional pinion obtained by subjecting a metal material to electrical discharge machining or cutting, or performing plastic working such as press molding or rolling molding cannot sufficiently satisfy these various requirements.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, to obtain a large reduction ratio by the reduction gear mechanism, to ensure a high degree of coaxiality between the motor shaft and the pinion, a pinion slip, etc. Motor for micro motors that can fully satisfy all the requirements such as the absence of defects, high pinion dimensional accuracy, high durability, easy manufacturing, etc. To provide a shaft.
Another object of the present invention is to provide a micro motor and a micro geared motor using such a motor shaft.

As described above, when a large reduction ratio is to be obtained in a micro geared motor, the gear diameter on the speed reduction gear mechanism side is increased to increase the number of teeth due to restrictions on the size (diameter) of the motor. I can't. Therefore, the present inventors have made a detailed study from the viewpoint of reducing the diameter of the pinion of the motor shaft, and at that time, compared with the conventional structure in which the pinion is joined to the motor shaft through the mounting hole, The idea was that the pinion was made extremely small by forming (molding) the pinion integrally with the shaft itself, that is, having a pinion diameter equal to or smaller than the shaft diameter. However, according to the conventional technical knowledge of those skilled in the art, in such a structure in which the pinion is made smaller than the motor shaft diameter, the pinion strength is extremely insufficient, and the pinion (= motor shaft (Part) damage and fatigue failure were expected to occur frequently. However, when the inventors actually produced a micro geared motor with the same structure and conducted a repeated operation test, the pinion was completely damaged due to insufficient strength or fatigue failure due to repeated load. It was found that durability with almost no problem in practical use was obtained. This is because a micro geared motor has a much smaller motor torque than a general motor or other small motors (usually several μNm to several hundred μNm), so even a pinion having a shaft diameter or less is not affected by the motor torque. It is thought that this is because of having sufficient strength, and is a performance specific to a micro geared motor that has not been known at all.
In addition, as a result of studying the material of the motor shaft with which the pinion is integrated by the present inventors, at least the pinion part is composed of a vitreous base alloy mainly composed of a vitreous metal structure, and thus, it is particularly excellent in high dimensional accuracy and It was found that durability was obtained.

The present invention has been made on the basis of the above idea and knowledge, and the gist thereof is as follows.
(1) A pinion having an outer diameter equal to or smaller than the outer diameter of the shaft is integrally formed on the distal end side of the shaft, and at least the pinion portion of the shaft includes a glassy metal structure at a volume ratio of 50% or more. A motor shaft for a micromotor, comprising a glassy base alloy.
(2) A motor shaft for a micromotor, characterized in that in the motor shaft of (1) above, the entire shaft is made of a vitreous base alloy.

(3) In the motor shaft according to (1) or (2) above, at least a tip side portion including a pinion portion of the shaft is made of a vitreous base alloy, and a shaft main body portion to which the tip side portion is joined is a crystalline metal material. A motor shaft for a micromotor, comprising:
(4) A motor shaft for a micromotor, wherein the motor shaft according to (3) is formed by casting a tip side portion in contact with a shaft main body portion.
(5) In the motor shaft according to any one of (1) to (4), at least the pinion portion satisfies at least one of Vickers hardness Hv500 or more and tensile strength 1500 MPa or more. Motor shaft.

(6) A motor shaft for a micromotor, wherein the surface roughness Ry of at least the pinion portion is 2 μm or less in any of the motor shafts of the above (1) to (5).
(7) A motor shaft for a micromotor, wherein the motor shaft of any one of (1) to (6) above has an outer diameter of 1 mm or less.
(8) A micromotor comprising the motor shaft according to any one of (1) to (7) above.
(9) The micromotor according to (8), wherein the outer diameter is 4 mm or less.

(10) A motor unit including the micro motor of (8) or (9) above, and a reduction gear head unit that is drivingly connected to the motor unit via a pinion formed on the motor shaft. A featured micro geared motor.
(11) In the micro geared motor of (10), the reduction ratio between the pinion formed on the motor shaft of the motor unit and the first reduction gear of the reduction gear head unit is 5 or more. The number of teeth of the pinion and the reduction gear is set.
(12) The micro geared motor according to (10) or (11), wherein the motor portion is a brushless motor, and the speed reduction gear mechanism of the speed reduction gear head portion is a planetary gear speed reduction mechanism.
(13) The micro geared motor according to any one of (10) to (12), wherein the outer diameter is 4 mm or less.

  According to the motor shaft for a micromotor according to the present invention, and the micromotor and the micro geared motor to which the motor shaft is applied, the pinion can be sufficiently reduced in diameter, so that a large reduction ratio can be obtained by the reduction gear mechanism. In addition, since the pinion is integrally formed on the motor shaft itself, a high degree of coaxiality between the motor shaft and the pinion can be ensured, so that a motor with less failure and longer life and less noise generation can be obtained. In addition, problems such as pinion slip do not occur. In addition, there is an advantage that the number of manufacturing steps and the manufacturing cost can be reduced because a pinion bonding process by bonding, press fitting, or the like is unnecessary. Furthermore, since at least the pinion portion is made of a vitreous base alloy, the pinion portion can be provided with high dimensional accuracy and durability.

1 and 2 show an embodiment of a motor shaft of the present invention and a micro geared motor to which the motor shaft is applied. FIG. 1 is a longitudinal sectional view, and FIG. 2 is a sectional view taken along line II-II in FIG. It is.
In the figure, reference numeral 1 denotes a motor unit composed of a micro motor, and 2 denotes a reduction gear head unit that is connected to the motor unit 1 through a pinion of a motor shaft. In this embodiment, the micromotor of the present invention is not provided with the reduction gear head portion 2.

  In the present invention, the mechanism of the micromotor that constitutes the motor unit 1 is arbitrary. For example, a coreless motor, a brushless motor, or the like can be used. In this embodiment, the micromotor is configured by a brushless motor. That is, the motor unit 1 is externally fixed to the motor shaft portion between the housing 3A, the motor shaft bearings 4a and 4b, the motor shaft 5 rotatably held by the bearings 4a and 4b, and the bearings 4a and 4b. And a stator coil 7 which is fixed to the inside of the housing 3A so as to face the rotor magnet 6, and the structure itself is the same as that of a conventional micro geared motor.

A pinion 8 having an outer diameter equal to or smaller than the outer diameter of the motor shaft 5 is integrally formed (formed) at the tip of the motor shaft 5. Of this motor shaft 5, at least the pinion portion is composed of a vitreous base alloy containing a vitreous metal structure at a volume ratio of 50% or more. Specifically, the entire motor shaft may be made of the glassy base alloy, or the tip side portion including at least the pinion portion of the motor shaft is made of a glassy base alloy, and the tip side portion is joined. The formed shaft main body portion may be made of a crystalline metal material such as a steel material.
The pinion 8 is formed on the tip end side of the motor shaft 5, but the position thereof does not have to be the most distal portion of the motor shaft 5.

3A to 3E show various structural examples of the motor shaft.
Among these, the motor shaft 5 in FIG. 3A is configured by constituting the entire shaft including the pinion 8 with a vitreous base alloy. Such a motor shaft 5 can be manufactured, for example, by casting using a precision injection technique of molten metal. Moreover, it can also shape | mold by giving cutting processing, rolling processing, etc., such as hobbing, to the front-end | tip of the round bar of a vitreous base alloy. In this way, when the pinion 8 is formed by cutting or rolling the motor shaft 5 itself, the shaft member made of a glass-based alloy round bar is centerless processed to obtain the outer diameter dimensional accuracy and surface roughness. After the adjustment, the pinion 8 is formed (formed) by cutting or rolling at the tip, and then the motor shaft 5 provided with the pinion 8 is finished through processes such as heat treatment and barrel polishing. FIG. 4 shows the pinion 8 formed by hobbing the tip of the motor shaft 5, and the range indicated by P in the drawing is a substantial pinion portion.

In the motor shaft 5 of FIG. 3B, only the pinion 8 is made of a vitreous base alloy, and the other shaft body portion 50 is made of a crystalline metal material such as a steel material (for example, stainless steel). . The motor shaft 5 in FIG. 3B has a structure in which a deformed small-diameter portion 80 at the rear end of the pinion 8 (pinion portion) is fitted into the deformed hole 501 at the tip of the shaft main body portion 50.
3 (c) to 3 (e), the shaft tip side portion 51 including the pinion 8 is made of a vitreous base alloy, and the other shaft main body portion 52 is made of a steel material (for example, stainless steel). It is composed of a crystalline metal material such as In this example, the shaft front end portion 51 including the portion supported by the bearing 4a is made of a vitreous base alloy. Here, the motor shaft 5 in FIG. 3C has a structure in which the small diameter portion 520 at the tip of the shaft main body portion 52 is fitted in the hole 510 at the rear end of the shaft tip side portion 51, as shown in FIG. The motor shaft 5 has a structure in which a modified small-diameter portion 521 at the front end of the shaft main body portion 52 is fitted into a modified hole 511 at the rear end of the shaft front end portion 51. The motor shaft 5 in FIG. This is a structure in which a modified small-diameter portion 512 at the rear end of the shaft distal end portion 51 is fitted into the modified hole 522 at the distal end of the portion 52.

  Generally, the motor shaft 5 having the structure shown in FIGS. 3B to 3E is manufactured by casting the pinion 8 or the shaft tip side portion 51 in contact with the shaft main body portions 50 and 52. Among these, in the motor shaft 5 shown in FIGS. 3C and 3D, the rear half portion or the rear end portion of the shaft front end portion 51 has the small diameter portion 520 or the deformed small diameter portion 521 at the front end of the shaft body portion 52. The shaft tip side portion 51 is cast as if it is cast, and a strong joint structure between the shaft tip side portion 51 and the shaft body portion 52 is obtained by this cast portion. 3B and 3E, the pinion 8 or the rear end portion of the shaft front end portion 51 is cast into the deformed holes 501 and 522 at the front ends of the shaft main body portions 50 and 52. Thus, the pinion 8 or the shaft front end portion 51 is cast, and a strong joint structure between the pinion 8 and the shaft main body portion 50 or between the shaft front end portion 51 and the shaft main body portion 52 is obtained by this casting portion.

  FIG. 5 shows a specific example of a method for manufacturing the motor shaft 5 as shown in FIGS. 3 (a) to 3 (e) by casting the whole or a part thereof, and 17 is a mold. The fixed type 18 is also a movable type. The fixed mold 17 has a casting space for casting a shaft main body part or an insertion hole for storing and holding a pre-manufactured shaft main body part, while the movable mold 18 is a pinion or a shaft front end side including a pinion. A casting space for casting a portion is provided, and the movable die 18 is movable with respect to the fixed die 17 in the motor shaft axial direction. Since the motor shaft of the present invention is integrally formed with a pinion having an outer diameter equal to or less than the outer diameter of the shaft, the cast body can be pulled out by moving the movable die 18 in the axial direction of the motor shaft after the casting is completed. A motor shaft with a small amount can be easily manufactured.

  FIG. 5A shows a case where the entire motor shaft is integrally cast in order to obtain the motor shaft as shown in FIG. 3A, and the fixed mold 17 has a casting space 170 for the shaft main body portion. However, a casting space 180 for the shaft tip side portion is formed in the movable mold 18, and the casting space of the entire motor shaft is configured by assembling both molds 17 and 18. A runner 181 leading to the casting space is formed on the lower surface of the movable mold 18. In this embodiment, hot water (molten metal) is supplied through a runner 181 into a casting space constituted by both molds 17 and 18, and the motor shaft 5 is integrally cast. The runner (solidified metal in the runner 181) connected to the cast motor shaft 5 is removed later.

  FIG. 5B shows a case where the pinion 8 is cast on the shaft body portion 50 in order to obtain the motor shaft 5 as shown in FIG. An insertion hole 171 for holding 50 is formed, and a casting space 180 for a pinion is formed in the movable die 18. In addition, a runner 181 leading to the casting space 180 is formed on the lower surface of the movable mold 18. In this embodiment, after inserting the manufactured shaft main body portion 50 into the insertion hole 171 of the fixed die 17, the movable die 18 is assembled, and the pinion casting space 180 is positioned above the shaft main body portion 50. In this state, hot water (molten metal) is supplied into the casting space 180 through the runner 181, and the pinion 8 is cast at the tip of the shaft body portion 50. The runner (solidified metal in the runner 181) connected to the cast pinion 8 is removed later. Normally, the tip of the shaft main body portion 50 is provided with a hole or a small diameter portion (not shown) for obtaining a joining structure as shown in FIG.

  FIG. 5C shows a case where the shaft tip side portion 51 is cast with respect to the shaft main body portion 52 in order to obtain the motor shaft 5 as shown in FIGS. The mold 17 is formed with an insertion hole 171 for holding the shaft body portion 52, and the movable mold 18 is formed with a casting space 180 for the shaft tip side portion. In addition, a runner 181 leading to the casting space 180 is formed on the lower surface of the movable mold 18. In this embodiment, after inserting the manufactured shaft body portion 52 into the insertion hole 171 of the fixed die 17, the movable die 18 is assembled, and the casting space 180 for the shaft tip side portion is positioned above the shaft body portion 52. Let In this state, hot water (molten metal) is supplied into the casting space 180 through the runner 181, and the shaft distal end portion 51 is cast at the distal end of the shaft main body portion 52. The runner (solidified metal in the runner 181) connected to the cast shaft main body portion 52 is later removed. Normally, the tip of the shaft main body 52 is provided with a hole or a small diameter portion (not shown) for obtaining a joining structure as shown in FIGS.

  As mentioned earlier, motors larger than micro motors among general size motors and small motors have a corresponding motor torque, so if the pinion diameter is made too small, a large stress is applied to the tooth part. Breakage and fatigue failure can easily occur. In contrast, in the case of a micromotor having an outer diameter of 4 mm or less in general, the motor torque is as small as several μNm to several hundred μNm, and even if the maximum load is applied by locking, the pinion teeth It was found that fatigue damage due to partial breakage and repeated loading is unlikely to occur. And it turned out that it becomes hard to produce especially the damage of the tooth | gear part of a pinion, and fatigue failure by comprising at least a pinion part with a vitreous base alloy like this invention. Incidentally, the motor torque of the 2 mm diameter micromotor that the inventors made as a prototype was 7 μNm.

  In the present invention, the outer diameter of the pinion 8 is set to be equal to or smaller than the outer diameter of the motor shaft 5 in order to obtain a large reduction ratio by reducing the diameter of the pinion, but the motor shaft 5 itself is cut or rolled. In the case where the pinion 8 is formed by processing, etc., setting the outer diameter of the pinion 8 to be equal to or smaller than the outer diameter of the motor shaft 5 has the following advantages. That is, when the pinion outer diameter is made larger than the motor shaft outer diameter, the motor shaft in the blank state before the pinion is formed into a stepped bar shape with a different diameter, and in particular the outer diameter accuracy of the machined motor shaft. It becomes difficult to finish the surface roughness with high accuracy. On the other hand, if the pinion outer diameter is smaller than the motor shaft outer diameter, the motor shaft in the blank state before the pinion is formed into a round bar shape without a step, and by performing centerless processing, the outer diameter accuracy of the motor shaft is increased. Surface roughness is finished with high accuracy. Then, the pinion is processed on the motor shaft processed in this way, and the motor shaft 5 having the pinion 8 is finished through processes such as heat treatment and barrel polishing.

  If the outer diameter of the pinion formed integrally with the motor shaft is larger than the outer diameter of the motor shaft, the rotor magnet is fixed with an adhesive or the like while the motor shaft is passed through the bearing (gearhead side) from the front side. However, if the bearing is interposed, it is difficult to fix the motor shaft and the rotor magnet in a highly accurate positional relationship, and if the adhesive protrudes, the wiping process becomes difficult. In this regard, in the case of the present invention in which the outer diameter of the pinion 8 is smaller than the outer diameter of the motor shaft 5, the motor shaft 5 and the rotor magnet 6 can be fixed in advance, so that high-accuracy and easy assembly is possible. .

Next, the vitreous base alloy constituting at least the pinion portion of the motor shaft will be described.
A pinion portion (hereinafter simply referred to as “pinion”) composed of a vitreous base alloy having a vitreous metal structure has high strength / hardness and surface smoothness. However, when the volume ratio of the vitreous metal structure is less than 50%, such characteristics cannot be sufficiently obtained. Therefore, in the present invention, the volume ratio of the vitreous metal structure in the vitreous base alloy is set to 50% or more.
The vitreous base alloy constituting the pinion may have a metallic structure in which nanocrystalline grains having a particle diameter of 100 nm or less are mixed in a vitreous metallic structure. In general, when crystals are contained in the vitreous structure of a vitreous base alloy, the mechanical properties such as high strength of the alloy tend to be reduced, but the volume fraction of the vitreous metal structure is 50% or more. For example, almost no deterioration in mechanical properties is observed.
However, if the grain size of the crystal grains exceeds 100 nm, the surface roughness (surface smoothness) of the pinion is adversely affected. Therefore, the grain size of the crystal grains mixed in the matrix of the vitreous metal structure is 100 nm or less. It is desirable. On the other hand, it is known that when crystal grains having excellent toughness and malleability are mixed in a glassy metal structure matrix, the mechanical properties are improved. In this case, the grain size of the crystal grains is 20 nm. The following is more preferable.

  The vitreous base alloy constituting the pinion is an alloy having the following composition in particular, that is, one or more elements such as Fe, Co, Ni, Cu, Ti, Zr, and Hf as a main component. It is preferable to use a glassy base alloy having a ternary system or a quaternary system or higher composition. Such a glassy base alloy is characterized in that the XRD pattern is formed of a disordered structure having a halo pattern, that is, a broad peak and having no regularity, and this glassy base alloy is used. Thus, a pinion having mechanical properties (particularly strength and hardness) comparable to tool steel and excellent workability, surface smoothness, and dynamic characteristics can be obtained.

(B) M _100-n TM _n (where M is one or more elements selected from Fe, Co, Ni, Cu, Ti, Zr, Hf, and TM is Cr, Mo , Nb, Al, Sn, B, containing 1 atomic% or more of one or more elements selected from the group consisting of Group 3, 4, 5, 6, 8, 9, 9, And 11 group transition metal elements (except for elements applied to Cr, Mo, Nb and M), 13 group, 14 group and 15 group typical elements (however, excluding Al, Sn, B) It is composed of one or two or more elements selected, and 100-n, n represents each atomic% of M and TM, and n is 5 atomic% to 50 atomic%. Glassy base alloy.
In the alloy composition of (a) above, it is difficult to form a vitreous metal structure if n is less than 5 atomic%, while it is possible to form a vitreous metal structure even if n exceeds 50 atomic%. However, the strength / hardness and dimensional accuracy are liable to decrease. In addition, by including one or more elements selected from Fe, Co, Ni, Cu, Ti, Zr, and Hf as TM, ordering of the disordered structure due to crystallization is suppressed, and more A highly stable pinion that is thermally stable can be obtained.

(B) Cu _p Ti _q M1 _100-pq (where M1 is one or two selected from Hf, Zr, iron group element, platinum group element, Ag, Au, Al, Sn, Zn) Composed of the above elements, p, q, 100-pq represents each atomic% of Cu, Ti, M1, p is 50 atomic% to 65 atomic%, and q is 2 atomic% to 20 atomic%. A glassy base alloy having a composition represented by:
The vitreous base alloy having the above composition (b) (composition mainly composed of Cu) exhibits a tensile strength of 1800 MPa or more and a very large elongation strain exceeding 3.5%, and has high strength and fracture resistance. Remarkably better. In the alloy composition of (b), when p is less than 50 atomic%, the strength and hardness are lowered, whereas when it exceeds 65 atomic%, excellent fracture resistance cannot be obtained. Further, when q is less than 2 atomic%, the elongation strain limit is lowered. On the other hand, when q exceeds 20 atomic%, it is difficult to obtain excellent surface smoothness. Further, in order to obtain particularly excellent fracture resistance, it is desirable to contain Hf and / or Zr as M1 in a range of 10 atomic% to 40 atomic%, more preferably 20 atomic% to 35 atomic%.

(C) Ni _100-s-t Nu _s (Zr, Hf) _t M2 _u (where (Zr, Hf) represents “Zr and / or Hf”, M2 represents Ti, iron group element, platinum It consists of one or more elements selected from group elements, Ag, Au, and 100-s-tu, s, t, u are each of Ni, Nb, (Zr, Hf), M2 Represents atomic%, s is 10 atomic% to 25 atomic%, t is 5 atomic% to 20 atomic%, u is 5 atomic% to 25 atomic%, and the sum of t and u is 10 atomic% to 35 atomic% % Or less)).

The vitreous base alloy having the above composition (c) (composition mainly composed of Ni) is tenacious because all the constituent elements are transition metal elements, and further has high hardness and tensile strength because it is mainly composed of Ni. Have. In addition, Ni—Nb-based alloys such as this vitreous base alloy form a passive film in an oxidizing atmosphere, and the material is hardly deteriorated by oxidation. The advantage is that a non-lubricated gear mechanism can be formed and dynamic characteristics free from resistance due to the viscosity of the lubricating oil can be enjoyed to the maximum. In the alloy composition of (c), a glassy metal structure can be obtained even when s is 15 atomic% larger than the maximum value and t and u are less than the lower limit values or not present, respectively. Conditions become severe, and it becomes difficult to ensure excellent dimensional accuracy and surface accuracy. In addition, the other numerical limits relating to s, t, u, and t + u limit the range in which excellent dimensional accuracy and surface accuracy (surface roughness Ry 2 μm or less) can be secured under the processing conditions in the known manufacturing method. .
From the same viewpoint, M2 preferably contains 5 atomic% or more and 20 atomic% or less of Ti.

(D) Fe _100-xy M3 _x M4 _y (where M3 is composed of one or more elements selected from Group 3, Group 4, Group 5 and Group 6 transition metal elements; M4 is composed of one or more elements selected from Mn, Ru, Rh, Pd, Ga, Al, Ge, Si, B, and C, and 100-xy, x, and y are Fe, A glass-based alloy having a composition represented by the following formula: M3 and M4, wherein x is 2 atomic% to 35 atomic% and y is 5 atomic% to 30 atomic%.
The vitreous base alloy having the above composition (d) (composition mainly composed of Fe) is particularly hard and has a characteristic that hardly undergoes elastic deformation. In this alloy composition (d), dimensional accuracy and surface smoothness are obtained regardless of whether x is less than 2 atomic% or more than 35 atomic%, and y is less than 5 atomic% or more than 30 atomic%. Is significantly reduced.

(E) (Fe _1-a (Co, Ni) _a ) _100-xy M3 _x M4 _y (where (Co, Ni) represents “Co and / or Ni”; It consists of one or more elements selected from Group 5, Group 5 and Group 6 transition metal elements, and M4 is Mn, Ru, Rh, Pd, Ga, Al, Ge, Si, B, C. 1-a, a represents the atomic fraction of Fe, (Co, Ni), and 100-xy, x, y represents (Fe _{1 -A} (Co, Ni) _a ), M3 and M4 are represented by atomic%, a is 0.1 or more and 0.7 or less, x is 2 to 35 atomic%, and y is 5 to 30%. A glassy base alloy having a composition represented by:

As in the alloy composition of (e), by replacing a part of Fe, which is the main component in the alloy composition of (d), with Co and / or Ni, the hardness and strength are slightly reduced. Molding is facilitated due to the decrease and the viscosity of the molten metal, and more excellent dimensional accuracy and surface smoothness can be obtained.
In the alloy composition of (e), if the atomic fraction of a is less than 0.1, the effect of lowering the melting point by adding Co and Ni is hardly obtained, while if it exceeds 0.7, the strength is secured by Fe. The effect to do is not obtained sufficiently. From such a viewpoint, the more preferable range of the atomic fraction of a is 0.2 or more and 0.6 or less. The reason for limiting x and y is the same as that of the alloy composition (d) described above.

(F) A glassy base alloy containing at least B and / or Si as M4 in the glassy base alloy of (iv) or (e).
The vitreous base alloy mainly composed of Fe in the above (d) and the vitreous based alloy mainly composed of Fe, Co and / or Ni in the above (e), particularly when B and / or Si are contained as M4. In addition to being an inexpensive alloy, the presence of these metalloid components more effectively suppresses elastic deformation with respect to the load, and the pinion has a small and thin tooth deflection (which occurs before and after tooth meshing). Can be made extremely small. Moreover, since the surface smoothness is extremely good, it can be said that it is the most advantageous alloy for downsizing of the pinion. In this case, the preferable total content of Fe, Co, and Ni is 70 atomic% or more. Moreover, the preferable range of x is 2 atom% or more and 10 atom or less, and when x is less than 2 atom% and more than 10 atom%, it becomes difficult to obtain excellent accuracy and surface smoothness.

(G) (Zr, Hf) _a M5 _b M6 _c (where (Zr, Hf) represents “Zr and / or Hf”, and M5 represents a transition metal element of group 3, 5 and 6 or iron group It consists of one or more elements selected from elements, platinum group elements, Ag, Au, Ti, and Mn, and M6 is selected from Be, Zn, Al, Ga, B, C, and N. It consists of one or more elements, and a, b, and c represent (% of Zr, Hf), M5, and M6, and a is 30 atomic% to 70 atomic%, and b is 15 atomic%. The glassy-base alloy having a composition represented by the formula: 65 atom% or less and c is 1 atom% or more and 30 atom% or less.

The vitreous base alloy having the above composition (G) (composition mainly composed of Zr and / or Hf) has a particularly wide supercooled liquid temperature range, and a complex shape is easily obtained even when the cooling rate is relatively low. It has characteristics and particularly excellent dimensional accuracy and surface smoothness can be obtained. The surface hardness of this alloy is the lowest among the above-mentioned other alloys having a Vickers hardness Hv of about 500, but the main component is Zr and / or Hf effective for corrosion resistance, so it can be used outdoors or in corrosive environments. It is possible to construct a pinion made of an element group which is possible and has a particularly low biotoxicity, which is particularly advantageous for medical use.
In this (g) alloy composition, if a is less than 30 atomic%, excellent corrosion resistance cannot be obtained, while if it exceeds 70 atomic%, high dimensional accuracy and surface smoothness cannot be obtained. In addition, if b and c are out of the specified range, poor filling is likely to occur in the tooth portion, and durability is lowered.

(H) Ti _100- ijk Cu _i M7 _j M8 _k (where M7 is composed of one or more elements selected from Zr, Hf, iron group elements, platinum group elements, M8 is composed of one or more elements selected from Group 3, Group 5 and Group 6 transition metal elements, Al, Sn, Ge, Si, B, and Be, and 100-ijk , I, j, k represent atomic percent of Ti, Cu, M7, M8, i is 5 atomic percent to 35 atomic percent, j is 10 atomic percent to 35 atomic percent, and k is 1 atomic percent or more. The glassy base alloy having a composition represented by:

  The vitreous base alloy having the above composition (h) (composition mainly composed of Ti) has the second highest strength after the alloy mainly composed of Fe group, and Ti has a low specific gravity. In particular, a lightweight pinion can be obtained, and a gear mechanism with low torque loss at startup can be obtained. In the alloy composition of (h), if the i and j are less than the lower limit values specified, excellent surface smoothness cannot be obtained. On the other hand, if the upper limit value is exceeded, the advantage is that Ti is the main component due to the increase in specific gravity. Sex disappears. In addition, in any case where k is less than 1 atomic% or more than 20 atomic%, it is difficult to obtain a desired vitreous metal structure because the metal is not appropriately vitrified during casting.

  The glassy base alloys (a) to (h) listed above can produce pinions having a surface roughness Ry of 2 μm or less and a dimensional accuracy of ± 5 μm. It is an extremely useful alloy for obtaining a fine pinion having excellent characteristics and high dimensional accuracy. In addition, the pinion needs to make the surface pressure distribution uniform and suppress the generation of local stress as much as possible, but the pinion made of the glassy base alloy enables smooth gear transmission by improving the surface roughness and dimensional accuracy, As a result, the surface pressure distribution is made uniform, the occurrence of local stress is suppressed, and a pinion with high loss and low durability can be realized. Further, the pinion made of the glassy base alloy can form an extremely gentle uneven surface having no micron-order edge portion, so that the pressure distribution on the tooth surface is made uniform and microscopic. Troubles such as defects are suppressed, and high durability can be realized from this point. Unlike pinions made of crystalline metal with regularity, it is a disordered structure with no orientation, and has a structure that is strong against external stress from all directions, so it is ultra-precise and reliable with no cracks or chips. A high pinion is obtained.

  In addition, it is known that the higher the hardness of the alloy, the more remarkable the embrittlement is seen, and it is known that the resistance to gear surface fatigue such as pitching is greatly adversely affected. Because of its low Young's modulus, it has excellent gear surface fatigue resistance such as pitching, despite having high hardness. Moreover, in order to express this effect notably, it is desirable that the amount of nonmetallic elements in the vitreous base alloy is 30 atomic% or less. In particular, when the amount of nonmetallic elements is 25 atomic% or less, even in the vitreous base alloy containing the hardest Fe as a main component, the bending strain until yielding or breaking is 1.5% or more, A tenacious pinion can be formed.

  Further, in order to have the same hardness and strength as tool steel, the pinion satisfies at least one of Vickers hardness Hv500 (equivalent to Rockwell hardness HRc49) and tensile strength 1500 MPa or more, preferably both. However, the pinion of the present invention made of a glassy base alloy, particularly the pinion made of the glassy base alloys (i) to (h) described above, can easily achieve such hardness and strength. .

  The vitreous base alloy preferably has a supercooled liquid region of 30 K or more at a temperature rising rate of 0.67 K / s. The vitreous base alloy exhibits stable temperature change characteristics from the molten liquid to the supercooled liquid region to the glass solid. In particular, a vitreous base alloy having a supercooling temperature region of 30 K or higher at a heating rate of 0.67 K / s has high stability as a glass solid, and therefore injection molding, extrusion molding, and pressure rolling molding by viscous flow. The pinion can be manufactured with high accuracy by using a molding process that is inexpensive and has high shape reproducibility.

When obtaining a vitreous base alloy to be applied to a pinion (including the case of directly casting a pinion with the same alloy), in order to suppress volume shrinkage from the molten metal regardless of the stability of the disordered structure, 300 It is preferable to cool and solidify at a cooling rate of at least ° C / second. Further, a more preferable cooling rate is 10 ⁴ ° C / second or more. However, if the cooling rate at the time of casting molding exceeds 10 ⁷ ° C / second, the molten metal starts to solidify before it is sufficiently filled in the mold, which tends to cause poor filling. As a result, the surface roughness and dimensional accuracy are significantly reduced. For this reason, the cooling rate during casting is preferably 300 ° C./second or more (more preferably 10 ⁴ ° C./second or more) and 10 ⁷ ° C./second or less.

The results of integral casting of the motor shaft of the present invention composed of the glassy base alloys of the above (a) to (h) using a known pressure casting molding apparatus are shown below. In casting the motor shaft, the molten metal was rapidly solidified at a cooling rate of about 10 ³ to 10 ⁴ ° C / second.
The pinion portion of the manufactured motor shaft was measured and evaluated for surface appearance, dimensional error, tooth surface roughness Ry / surface hardness (Vickers hardness Hv), tensile strength, elongation strain, and XRD pattern. The results are shown in Table 1. As for the dimensional error, the dimensional error of the inner circumference diameter of the pinion was measured with a tool microscope. The surface roughness Ry of the tooth surface was measured with a non-contact type roughness meter, and the surface hardness was measured with a load of 100 g to 1 kg using a micro Vickers hardness meter. Tensile strength is measured by fixing a 60 μm thick and 50 μm wide foil body corresponding to the thickness of a tooth with a 0.20 mm width using a desktop tensile tester with an analysis function. The length was measured. The XRD pattern was measured using a micro X-ray diffractometer, and the halo pattern (G), the halo pattern with a mixture of peaks (G + C), and the crystal pattern completely (C) ). Here, (G) is an amorphous symbol, and (C) is a symbol representing a crystal.

Although there is no special restriction on the outer diameter of the motor itself or the motor shaft 5 of the present invention, as described above, even when the pinion 8 having the shaft diameter or less is integrally formed on the motor shaft 5 of the micromotor. The pinion has sufficient strength in terms of strength, which is a property unique to micromotors with very low motor torque. From this point of view, the motor outer diameter is 4 mm or less, and the motor shaft A micromotor having a 5 outer diameter of 1 mm or less (micro geared motor) is suitable.
Further, the outer diameter of the pinion 8 only needs to be smaller than the outer diameter of the motor shaft 5, and the lower limit of the outer diameter of the pinion is not particularly limited, but is generally at least about 80% of the outer diameter of the motor shaft 5 from the viewpoint of strength. It preferably has an outer diameter.

The speed reduction gear head portion 2 is disposed on the output side (tip side) of the housing 3B, the speed reduction gear mechanism portion 9 to which the pinion 8 is drivingly connected, and an output shaft rotatably supported by the bearing 11 The pinion 8 meshes with the first gear of the reduction gear mechanism 9.
The structure of the speed reduction gear mechanism section 9 included in the speed reduction gear head section 2 is arbitrary, and various structures can be applied. In this embodiment, the speed reduction gear mechanism section 9 is constituted by a planetary gear speed reduction mechanism. The basic structure of this planetary gear speed reduction mechanism is the same as the conventional mechanism as shown in FIG. 6, and in this embodiment, two sets of independent carriers are arranged in order from the motor unit 1 side to the output shaft 10 side. Units 12 a and 12 b and a set of carrier units 12 c provided at the base end of the output shaft 10 are provided.

Each of the carrier units 12a and 12b has three shaft portions 130 for supporting planetary gears on the surface on the motor portion side so as to protrude in an arrangement relationship of 120 ° in the circumferential direction, and the surface on the side opposite to the motor portion. A plate-like carrier 13 having a sun gear 15 projecting from the central portion thereof, and a planetary gear 14 rotatably supported by each of the shaft portions 130 (planetary gears 14 having an arrangement relationship of 120 ° in the circumferential direction) And.
Further, the carrier unit 12c has three shaft portions 130c for supporting the planetary gear on the surface on the motor portion side so as to protrude in the circumferential direction so as to be equally divided by 120 °, and the center of the surface on the side opposite to the motor portion A plate-like carrier 13c in which the output shaft 10 is fixed to the base end portion (or formed integrally with the base end portion), and a planetary gear 14c rotatably supported by the shaft portions 130c. Yes.
An internal gear 16 is provided on the inner surface of the housing 3B where the reduction gear mechanism 9 is disposed.

In the reduction gear mechanism 9 as described above, the planetary gears 14 and 14 c of the carrier units 12 a to 12 c mesh with the internal gear 16, and between adjacent carrier units 12, the sun gear 15 of the carrier unit 12 on the motor unit side. Meshes with the three planetary gears 14 and 14c of the carrier unit 12 on the non-motor side, and further, the pinion 8 of the motor shaft 5 meshes with the three planetary gears 14 of the first stage carrier unit 12a. Thereby, the rotation of the pinion 8 is transmitted to the output shaft 10 through the three carrier units 12a to 12c.
Reduction ratio = (Z3 / Z1 + 1)
Z1: Number of teeth of pinion 8 or sun gear 15
Z3: The rotational speed is sequentially reduced at a reduction ratio indicated by the number of teeth of the internal gear 16, and finally output from the output shaft 10.

  Here, the pinion 8 and the reduction gear are set so that the reduction ratio between the pinion 8 and the first reduction gear (in the present embodiment, the internal gear 16) of the reduction gear mechanism 9 is 5 or more. It is preferable to set the number of gear teeth. This reduction ratio of 5 or more is a reduction ratio that cannot be achieved by a conventional micro geared motor as shown in FIG. 6, but can be easily achieved according to the present invention.

An example of the reduction ratio obtained for the micro geared motor of the conventional example as shown in FIG. 6 and the micro geared motor of the example of the present invention as shown in FIG. 1 is shown below.
・ Conventional example Number of teeth of pinion (= sun gear) Z1: 14 Number of teeth of planetary gear Z2: 15 Number of teeth of internal gear Z3: 46 Reduction ratio = (Z3 / Z1 + 1) ≈4.286 (4.286) : 1)
-Example of the invention Number of teeth of pinion (= sun gear) Z1: 8 Number of teeth of planetary gear Z2: 18 Number of teeth of internal gear Z3: 46 Reduction ratio = (Z3 / Z1 + 1) ≈ 6.75 (6. 75: 1)

As described above, in the example of the present invention, the reduction ratio can be increased by 50% or more compared to the conventional example.
In the micro geared motor of the present invention, each of the gears constituting the reduction gear mechanism 9 to which the pinion 8 is drivingly connected also has a vitreous base alloy containing a vitreous metal structure at a volume ratio of 50% or more. It is preferable to use the glassy base alloys (A) to (H) described above. As a result, the above-described excellent characteristics are imparted to the gears constituting the reduction gear mechanism section 9, and the performance of the entire gear mechanism section of the micro geared motor is improved. Can be greatly improved.

The longitudinal cross-sectional view which shows one Embodiment of the micro geared motor of this invention Sectional drawing which follows the II-II line in FIG. Explanatory drawing which shows the structural example of the motor shaft of this invention The perspective view which shows the other structural example of the motor shaft of this invention Explanatory drawing which showed the specific example of the method of manufacturing the motor shaft of this invention by casting the whole or one part. A longitudinal sectional view showing an example of a conventional micro geared motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor part 2 Reduction gear head part 3A, 3B Housing 4a, 4b Bearing 5 Motor shaft 6 Rotor magnet 7 Stator coil 8 Pinion 9 Reduction gear mechanism part 10 Output shaft 11 Bearing 12a-12c Carrier unit 13, 13c Carrier 130, 130c Shaft portion 14, 14c Planetary gear 15 Sun gear 16 Internal gear 17 Fixed type 18 Movable type 170, 180 Casting space 171 Insertion hole 181 Runway 50, 52 Shaft body portion 51 Shaft tip side portion 510 Hole 501, 511, 522 Deformed hole 80, 512, 521 Modified small diameter part 520 Small diameter part

Claims (16)

  A pinion having an outer diameter equal to or smaller than the outer diameter of the shaft is integrally formed on the distal end side of the shaft, and at least the pinion portion of the shaft includes a vitreous metal structure at a volume ratio of 50% or more. A motor shaft for a micromotor, characterized by comprising an alloy.   The motor shaft for a micromotor according to claim 1, wherein the entire shaft is made of a vitreous base alloy.   3. The micro of claim 1, wherein a tip side portion including at least a pinion portion of the shaft is made of a vitreous base alloy, and a shaft main body portion to which the tip side portion is joined is made of a crystalline metal material. Motor shaft for motor. 4. The motor shaft for a micromotor according to claim 3, wherein the motor shaft is formed by casting a shaft tip side portion in contact with the shaft main body portion. 5. The shaft front end portion is cast such that the latter half portion or the rear end portion of the shaft front end portion casts a small diameter portion or a deformed small diameter portion formed at the front end of the shaft main body portion. The motor shaft for the described micromotor. 5. The pinion or shaft front end portion is cast such that the rear end portion of the pinion or shaft front end portion is cast into a deformed hole formed at the front end of the shaft main body portion. A motor shaft for a micromotor as described in 1. The motor shaft for a micromotor according to any one of claims 1 to 6 , wherein at least the pinion portion satisfies at least one of Vickers hardness Hv500 or more and tensile strength 1500MPa or more. At least the pinion portion, a motor shaft for a micromotor according to any one of claims 1 to 7, wherein the surface roughness Ry is 2μm or less. The motor shaft for a micromotor according to any one of claims 1 to 8 , wherein an outer diameter of the shaft is 1 mm or less. The motor shaft for a micromotor according to any one of claims 1 to 9, wherein the motor shaft is for a micromotor having an outer diameter of 4 mm or less. Micromotor, characterized in that it comprises a motor shaft according to any one of claims 1-10. The micromotor according to claim 11 , wherein an outer diameter is 4 mm or less. A motor unit composed of a micro-motor as claimed in claim 11 or 12, the micro to the motor unit, characterized in that it comprises a speed-reduction gear head unit which is drivingly connected via a pinion formed on the motor shaft Geared motor. The number of teeth of the pinion and the reduction gear is set so that the reduction ratio between the pinion formed on the motor shaft of the motor unit and the first reduction gear of the reduction gear head unit is 5 or more. The micro geared motor according to claim 13 . Motor unit is a brushless motor, a micro geared motor according to claim 13 or 14 reduction gear mechanism of the reduction gear head unit is characterized in that it is a planetary gear reduction mechanism. The micro geared motor according to any one of claims 13 to 15, wherein an outer diameter is 4 mm or less.

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