Gear device

There is provided a gear device including a motor having a motor shaft, a gear mechanism, a coupling that couples the motor shaft and an input shaft of the gear mechanism with each other, a first space accommodating the gear mechanism and holding a lubricant, a communication passage allowing the first space and a second space for accommodating the coupling to communicate with each other, and a blocking member disposed between the gear mechanism and the communication passage.

RELATED APPLICATIONS

Priority is claimed to Japanese Patent Application No. 2018-079904, filed Apr. 18, 2018, the entire content of which is incorporated herein by reference.

BACKGROUND

Technical Field

Certain embodiments of the present invention relate to a gear device.

Description of Related Art

In the related art, the present applicant discloses a gear power transmission device in which a casing internally accommodates a reduction gear unit that decelerates rotation of an input shaft so as to transmit the rotation to an output shaft.

In a gear power transmission device disclosed in the related art, a reduction gear unit includes a plurality of gears meshing with each other. The plurality of gears are lubricated by a lubricant held inside a casing. Since the gears are rotated, the lubricant may leak out of the casing. Depending on a usage, the gear power transmission device may be greatly affected by contamination resulting from the lubricant in some cases. Therefore, in a case where a large amount of the lubricant leaks out, an application range of the gear power transmission device is limited. For these reasons, the gear power transmission device disclosed in the related art has room for improvement in terms of preventing a leakage of the lubricant.

SUMMARY

According to an embodiment of the present invention, there is provided a gear device includes a motor having a motor shaft, a gear mechanism, a coupling that couples the motor shaft and an input shaft of the gear mechanism with each other, a first space accommodating the gear mechanism and holding a lubricant, a communication passage allowing the first space and a second space for accommodating the coupling to communicate with each other, and a blocking member disposed between the gear mechanism and the communication passage.

DETAILED DESCRIPTION

It is desirable to provide a gear device which can prevent a leakage of a lubricant.

According to an embodiment, the blocking member can be disposed between the gear mechanism and the communication passage.

Any desired combinations of configuration elements described above or substitutions between the configuration elements, expressions, methods, or systems according to the present invention may be effectively adopted as an embodiment of the present invention.

According to the present invention, it is possible to provide a gear device which can prevent a leakage of a lubricant.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the embodiments, comparative examples, and modification examples, the same reference numerals will be given to configuration elements or members which are the same or equivalent to each other, and repeated description will be appropriately omitted. In addition, dimensions of members in each drawing are appropriately enlarged and reduced in order to facilitate understanding. In addition, in each drawing, some members which are not important in describing the embodiments will be omitted in the illustration.

In addition, terms including ordinal numbers such as first and second are used to describe various configuration elements. However, the terms are used only to distinguish one configuration element from the other configuration element. The terms do not limit the configuration elements.

One Embodiment

Hereinafter, a configuration of a gear device100according to one embodiment will be described with reference toFIGS. 1 and 2. For example, the gear device100can be suitably used in a food factory which requires contamination control.FIG. 1is a front sectional view illustrating the gear device100according to the one embodiment.FIG. 2is a side view of the gear device100, and illustrates a partially broken casing. The gear device100according to the present embodiment has a motor10, a gear mechanism12, and a coupling16. The motor10has a motor shaft10b. The motor10is not particularly limited as long as the motor10can drive the gear mechanism12. The motor10according to the present embodiment is an AC servomotor. The gear mechanism12has a first shaft14serving as an input shaft and a fourth shaft22serving as an output shaft, and decelerates rotation input to the first shaft14so as to output the rotation from the fourth shaft22. Hereinafter, a direction extending along a central axis La of the first shaft14will be referred to as an “axial direction”. A circumferential direction and a radial direction of a circle centered on the central axis La will be respectively abbreviated as a “circumferential direction” and a “radial direction”.

Coupling

The coupling16will be described. The coupling16couples the motor shaft10band the first shaft14with each other. The coupling16may be a known coupling based on various principles. For example, the coupling16may be a spline coupling which cuts a spline between the shaft and the coupling, or may be a key coupling using a key. The coupling16includes a plurality of set screws16b. A coupling target shaft is inserted into the coupling16in a state where the set screws16bare loosened. In this manner, the set screws16bare fastened, thereby fixedly coupling the coupling16with the coupling target shaft by means of friction fastening. The set screws16bis fastened using a tool (not illustrated) inserted from an opening portion (to be described later).

The gear device100according to the present embodiment has a casing32for accommodating the gear mechanism12and the coupling16. The casing32can be formed of various materials, and is formed by means of aluminum die casting according to the present embodiment. The casing32includes a first casing32aillustrated on a right side of a parting32pin the drawing and a second casing32billustrated on a left side of the parting32p. The first casing32aand the second casing32bdefine a first space50for accommodating the gear mechanism12. The second casing32bdefines a second space52for accommodating the coupling16together with an end surface of the motor10. The first space50is a space where external air introduction and internal air discharge are substantially prevented. The first space50holds a lubricant60for lubricating the gear mechanism12. The second space52is a space for communicating with an exterior via a clearance (to be described later).

Communication Passage

If internal pressure of the first space50increases due to temperature rise during an operation, there is a possibility that the lubricant60may be ejected from an oil seal. Therefore, the gear device100according to the present embodiment has a communication passage56allowing the first space50and the second space52to communicate with each other. It is preferable that the communication passage56is disposed at a position separated upward from a region where the lubricant60is always present. According to the present embodiment, the communication passage56is located on a vertically upper side of the gear mechanism12. The communication passage56in this example is a hole drilled on the second casing32band penetrating in the axial direction. Since the gear device100has the communication passage56, the first space50communicates with the exterior via the communication passage56and the second space52.

Lubricant Storage

Since the gear device100has the communication passage56, mist of the lubricant60may enter the second space52from the first space50. Therefore, a lower surface32eof the second casing32bwhich defines a lower portion of the second space52functions as a lubricant storage for storing the lubricant60entering the second space52. After reaching the second space52, the lubricant60adheres to a wall surface surrounding the second space52. Thereafter, the lubricant60moves downward due to gravity, and is collected on the lower surface32e. According to this configuration, the lubricant60can be prevented from flowing outward.

Gear Mechanism

Next, the gear mechanism12will be described. As illustrated inFIG. 1, the gear mechanism12has a second shaft18and a third shaft20which serve as intermediate shafts, a plurality of gears disposed in the respective shafts, a plurality of bearings for rotatably supporting the respective shafts, and the lubricant60. The first shaft14, the second shaft18, the third shaft20, and the fourth shaft22respectively extend in the axial direction between the first casing32aand the second casing32b. The first shaft14, the second shaft18, and the third shaft20according to the present embodiment are solid shafts, and the fourth shaft22according to the present embodiment is a hollow shaft. The first shaft14, the second shaft18, and the third shaft20may be the hollow shafts, and the fourth shaft22may be the solid shaft.

The first shaft14is rotatably supported by first bearings41and42in the first casing32aand the second casing32b. A first driving gear24is fixed to the first shaft14. The second shaft18is rotatably supported by second bearings43and44in the first casing32aand the second casing32b. A second driven gear25meshing with the first driving gear24and a second driving gear26are fixed to the second shaft18.

The third shaft20is rotatably supported by third bearings45and46in the first casing32aand the second casing32b. A third driven gear27meshing with the second driving gear26and a third driving gear28are fixed to the third shaft20. The fourth shaft22is rotatably supported by fourth bearings47and48in the first casing32aand the second casing32b. A fourth driven gear29meshing with the third driving gear28is fixed to the fourth shaft22. The plurality of gears may be spur gears, but are helical gear in this example. The gear mechanism12configured in this way sequentially decelerates the rotation input to the first shaft14by using the plurality of gears, and outputs the rotation from the fourth shaft22.

In the gear mechanism12, the first shaft14, the second shaft18, the third shaft20, and the fourth shaft22are rotated in this order at high speed. That is, the first shaft14is a high speed shaft rotated at higher speed than the second shaft18, the third shaft20, and the fourth shaft22. The second shaft18, the third shaft20, and the fourth shaft22are low speed shafts rotated at lower speed than the first shaft14. In addition, the first shaft14, the second shaft18, the third shaft20, and the fourth shaft22are located in this order at a high position in a vertical direction. That is, the first shaft14is located at a higher position in the vertical direction than the second shaft18, the third shaft20, and the fourth shaft22. The second shaft18, the third shaft20, and the fourth shaft22are located at a lower position in the vertical direction than the first shaft14.

Lubricant

The lubricant60will be described. The lubricant60is not particularly limited as long as the lubricant60can lubricate the plurality of gears, and may be oil or grease. The lubricant60according to the present embodiment is high consistency (soft) grease in order to improve lubricity of the plurality of gears. The high consistency grease has higher fluidity due to temperature rise during the operation, and is likely to flow outward. Therefore, according to the present embodiment, in order to prevent the lubricant60from flowing outward, the blocking member54is disposed between the gear mechanism12and the communication passage56as illustrated inFIG. 1. The blocking member54will be described later.

If a liquid level60hof the lubricant60is excessively high, the lubricant60moves close to the communication passage56, thereby causing a possibility that the lubricant60may increasingly flow outward. Therefore, the liquid level60hof the lubricant60according to the present embodiment is set to be positioned on a vertically lower side of the first shaft14serving as the high speed shaft. In a case where the lubricant60is grease, the liquid level60hof the lubricant60shows a liquid level in a state where the lubricant60no longer moves when the operation is stopped. That is, the liquid level60hof the lubricant60shows a liquid level in a state where the lubricant60no longer moves using the gravity of the lubricant60adhering to the casing or the gear after a sufficient time elapses from when the operation is stopped.

Oil Seal

The second space52side of the first bearing41has an oil seal which prevents the lubricant60from flowing out to the second space52side. The oil seal according to the present embodiment includes two oil seals34continuously disposed in the axial direction. The two oil seals34are located between a through-hole which the first shaft14of the second casing32bpenetrates and the first shaft14. As the oil seal34, a known oil seal which prevents a leakage of the lubricant can be used. Since the first shaft14is rotated at relatively high speed, the oil seal34is likely to be progressively degraded. Therefore, in this example, two oil seals are located.

The oil seals36which prevent the lubricant60from flowing outward are respectively disposed on external space sides of the fourth bearings47and48. One of the oil seals36is located between the through-hole which the fourth shaft22of the first casing32apenetrates and the fourth shaft22. The other one of the oil seals36is located between the through-hole which the fourth shaft22of the second casing32bpenetrates and the fourth shaft22. As the oil seal36, a known oil seal which prevents a leakage of the lubricant can be used. Since the fourth shaft22is rotated at relatively low speed, the oil seal36is less likely to be degraded. Therefore, in this example, one oil seal is located.

The two oil seals34are located on the vertically upper side of the liquid level60hof the lubricant60. Even in a case where the oil seal34is degraded due to the high speed rotation, it is possible to reduce a possibility that the lubricant60may directly flow outward. The oil seal36is located on the lower side of the liquid level60hof the lubricant60. Since the oil seal36is filled with the lubricant60, the degradation of the oil seal36can be minimized.

Comparative Example

Prior to description of the blocking member54, a comparative example will be described with reference toFIG. 3.FIG. 3is an enlarged sectional view illustrating a periphery of the communication passage56of a gear device500according to the comparative example. The gear device500according to the comparative example is different from the gear device100according to the one embodiment in that the gear device500does not include the blocking member54. Other configurations are the same as those according to the one embodiment.

As illustrated inFIG. 3, if the gear of the gear mechanism12is rotated, the gear rolls up the lubricant60. A portion of the lubricant60adheres to the communication passage56so as to close the communication passage56. If the internal air is thermally expanded due to the rotation of the gear mechanism12and internal pressure of the first space50increases, the lubricant60closing the communication passage56is ejected from the communication passage56to the second space52side. While the gear mechanism12is rotated, the lubricant60is rolled up so as to close the communication passage56, and a cycle for ejecting the lubricant60to the second space52is continuously repeated. During the cycle, the lubricant60is continuously stored in the second space52. As a result, the amount of the lubricant60flowing outward of the second space52increases.

The gear device100according to the present embodiment will be described in contrast to the comparative example.FIG. 4is an enlarged sectional view illustrating the periphery of the communication passage56according to the present embodiment. According to the present embodiment, the blocking member54disposed between the gear mechanism12and the communication passage56blocks the lubricant60rolled up by the gear mechanism12. Accordingly, it is possible to significantly reduce the amount of the lubricant60reaching the communication passage56. As a result, a slight amount of the lubricant60enters the second space52. Therefore, it is possible to significantly reduce the lubricant60flowing outward.

Blocking Member

The blocking member54may be disposed at any location between the gear mechanism12and the communication passage56, as long as the lubricant60is blocked. The blocking member54according to the present embodiment is disposed between the first driving gear24closest to the communication passage56out of the gears of the gear mechanism12and the communication passage56. As illustrated inFIG. 4, the blocking member54horizontally protrudes toward the first casing32afrom the vicinity of the communication passage56of the second casing32b. The blocking member54has a hood shape which covers the upper side of the first driving gear24. In the blocking member54, a portion covering the upper side of the first driving gear24has an arc shape in a side view (refer toFIG. 2).

When viewed in the vertical direction, the blocking member54may be disposed so as to at least partially overlap the first driving gear24.FIGS. 5A and 5Bare top views illustrating the blocking member54and the first driving gear24of the gear device100.FIG. 5Aillustrates a state where the blocking member54overlaps a portion of the first driving gear24. In this case, a protruding amount of the blocking member54is small. Accordingly, the blocking member54can be easily formed.FIG. 5Billustrates a state where the blocking member54overlaps the whole first driving gear24. In this case, the blocking member54can more effectively prevent a leakage of the lubricant.

Opening Portion

Next, referring toFIG. 6, the opening portion58disposed in the second casing32bwill be described.FIG. 6is a front view illustrating the periphery of the opening portion58. The second casing32bwhich defines the second space52has the opening portion58into which a tool (not illustrated) for coupling the coupling16is inserted. The opening portion58has a size and shape which can operate the set screw16bof the coupling16by inserting the tool into the opening portion58. The opening portion58according to the present embodiment is a substantially rectangular opening disposed on the front surface side of the second casing32b. In the opening portion58, a peripheral edge58bfor attaching a plate-shaped cover member57is disposed so as to frame the opening. The cover member57is a substantially rectangular plate-shaped member, and is fixed to the peripheral edge58bwith a seal (not illustrated) interposed therebetween, for example, by using four screws57s. The cover member57is fixed by screwing the four screws57sto female screws58sdisposed in the peripheral edge58b.

As described above, a clearance59through which air flows via the opening portion58is disposed between the second space52and an external atmosphere. The clearance59according to the present embodiment is disposed between the cover member57and the peripheral edge58bof the opening portion58. As illustrated inFIG. 6, the clearance59is a linear groove formed in an upward-downward direction over the inside and the outside of the peripheral edge58b, and functions as a pas sage for allowing the second space52to communicate with the exterior.

An operation of the gear device100configured as described above will be described. If the motor shaft10bof the motor10is rotated, the first shaft14coupled via the coupling16is rotated. If the first shaft14is rotated, rotation thereof is sequentially decelerated by the first driving gear24, the second driven gear25, the second driving gear26, the third driven gear27, the third driving gear28, and the fourth driven gear29, and is transmitted to the fourth shaft22. If the fourth shaft22is rotated, a load device (not shown) coupled with the fourth shaft22is rotationally driven. Hitherto, the one embodiment has been described.

Another Embodiment

Next, a gear device200according to another embodiment will be described with reference toFIG. 7.FIG. 7is a side view illustrating the periphery of the blocking member54of the gear device200according to the other embodiment. In the drawing and the description of the other embodiment, the same reference numerals will be given to configuration elements or members which are the same as or equivalent to those according to the one embodiment. The descriptions repeated from the one embodiment will be appropriately omitted, and a configuration different from that according to the one embodiment will be mainly described. The other embodiment is different from the one embodiment in that the gear device200has a reinforcing member55for reinforcing the blocking member54and the reinforcing member55has a greasing hole55b, and the other configurations are the same as those according to the one embodiment.

Reinforcing Member

If the blocking member54is deformed, there is a possibility of coming into contact with the first driving gear24. Therefore, the other embodiment adopts the reinforcing member55which connects the second casing32band the blocking member54to each other so as to reinforce the blocking member54. A form of the reinforcing member55is not particularly limited as long as the blocking member54can be reinforced. The reinforcing member55according to the other embodiment is a rib-shaped portion extending downward from the upper portion of the second casing32band combined with the blocking member54. In this example, the reinforcing member55is integrally formed with the second casing32band the blocking member54. The communication passage56is located at a position avoiding the reinforcing member55.

Greasing Hole

According to the other embodiment, the greasing hole55bis disposed in order to supply the lubricant60to the first space50. A form of the greasing hole55bis not particularly limited as long as the lubricant60can be supplied. The greasing hole55baccording to the other embodiment penetrates the reinforcing member55upward and downward from the upper surface of the second casing32bto the lower surface of the blocking member54. In order to prevent the lubricant60from flowing outward and to prevent foreign matters from entering the greasing hole55b, a lid member55cfor closing the greasing hole55bis mounted on the greasing hole55b. A form of the lid member55cis not particularly limited as long as the lubricant60can be prevented from flowing outward. For example, a female screw may be formed in the greasing hole55b, and a male screw may be formed in the lid member55cso that these are screwed together.

According to the other embodiment configured as described above, the gear device200is operated in the same manner as the one embodiment, and the same operation and effect are achieved similarly to the one embodiment. Hitherto, the other embodiment has been described.

Hitherto, examples according to the embodiments of the present invention have been described in detail. The above-described embodiments are merely specific examples for embodying the present invention. Contents of the embodiments do not limit the technical scope of the present invention. Many design changes such as changes, additions, and deletions of the configuration elements can be made within the scope not departing from the concept of the invention stipulated in the appended claims. In the above-described embodiments, the contents which can be changed in design in this way have been described using terms of “in the embodiment” and “according to the embodiment”. However, as a matter of course, the design change is also allowed for the contents described without using the terms. In addition, a hatched cross section of the drawing does not limit a material of a hatched object.

Hereinafter, a modification example will be described. In the drawings and the description of the modification example, the same reference numerals will be given to configuration elements or members which are the same as or equivalent to those according to the embodiments. The description repeated from the embodiments will be appropriately omitted, and configurations different from those according to the one embodiment will be mainly described.

First Modification Example

In the one embodiment, an example has been described in which the blocking member54is disposed in the second casing32bso as to extend from the second casing32btoward the first casing32a. However, the present invention is not limited thereto. The blocking member54may be disposed in the first casing32aso as to extend from the first casing32atoward the second casing32b. Alternatively, the blocking member54may be disposed in both the second casing32band the first casing32a.

FIG. 8is a front view illustrating the periphery of the blocking member54according to a first modification example. The blocking member54in this example includes blocking members54band54chorizontally extending from mutually facing surfaces of the second casing32band the first casing32a. A clearance54sis disposed between the blocking members54band54cin order to relieve an increase in the internal pressure of the first space50. The blocking members54band54cmay be disposed at mutually different positions in a height direction.

In the one embodiment, an example has been described in which the gear device100adopts a parallel shaft type where the first shaft14on the input side and the fourth shaft22on the output side are arranged in parallel to each other. However, the present invention is not limited thereto. For example, the gear device100may adopt an orthogonal shaft type.

In the one embodiment, an example has been described in which the clearance59is disposed between the cover member57and the peripheral edge58bof the opening portion58. However, the present invention is not limited thereto. The clearance59is not limited to a position between the cover member57and the opening portion58. For example, the clearance59may be a hole formed in the cover member57.

Other Modification Examples

In the one embodiment, an example has been described in which the opening portion58is a substantially rectangular opening disposed on the front surface side of the second casing32bwhich defines the second space52. However, the present invention is not limited thereto. For example, the opening portion58may be disposed at a location other than the front surface side, such as the rear surface side and the upper surface side of the second casing32b. For example, if the opening portion is attached to the upper surface side, the lubricant is much less likely to leak outward of the opening portion. Alternatively, for example, the opening portion58may have a shape other than the rectangular shape, such as a circular shape and an oval shape.

In the other embodiment, an example has been described in which the reinforcing member55is integrally formed with the second casing32band the blocking member54. However, the present invention is not limited thereto. The reinforcing member55may be formed separately from the second casing32bor the blocking member54so that all of these are combined with each other.

According to the above-described respective modification examples, the same operation and effect are achieved similarly to the one embodiment.

Any desired combination of the above-described respective embodiments and modification examples is usefully adopted as an embodiment according to the present invention. A new embodiment adopted by the combination achieves both the respective effects of the respective embodiments and modification examples which are combined with each other.