JP7629892B2 - Drive unit - Google Patents

Description

The present invention relates to a driving machine, and more specifically, to a driving machine having a hollow shaft into which a load shaft is inserted and a power transmission mechanism that transmits power from a power source to the hollow shaft.

The inventors of the present application have devised a rotating shaft that is inserted into the insertion hole of a rotating body and fixed to the insertion hole, and that has multiple circumferential grooves in the circumferential direction of the shaft and recessed toward the inside of the shaft radial direction, and a communication passage that extends inside the shaft and communicates between the circumferential grooves and the outside of the rotating shaft, and at least one of the multiple circumferential grooves is arranged at each of both ends in the axial direction of a shielding part that is covered by the insertion hole and shielded from the outside, and the rotating shaft rotates together with the rotating body in a state in which the area between the circumferential grooves arranged at both ends is sealed from the outside through the communication passage by grease filled in the multiple circumferential grooves (see Patent Document 1). This rotating shaft has the excellent effect of preventing rusting of the parts shielded by the insertion hole and suppressing an increase in resistance when the rotating shaft is removed from the insertion hole.

In general, when fixing a hollow shaft (corresponding to the above-mentioned rotating body) of a driving machine such as a reducer or a transmission to a load shaft (corresponding to the above-mentioned rotating shaft), a method is used in which an end plate, or a spacer or a hole retaining ring is fixed to one end of the load shaft with a bolt. In the invention described in Patent Document 1, since one end of the communication passage is structured to open to one end of the load shaft, when replacing the internal grease, it is necessary to loosen the bolt and remove the end plate, or the spacer or the hole retaining ring. Therefore, the process required for replacing the internal grease is time-consuming. Thus, there is room for improvement in order to make it easier to replace the internal grease.

Patent No. 7038465

The object of the present invention is to provide a drive that makes it easier to replace the grease that prevents rust on the inner surface of the hollow shaft and the outer surface of the load shaft.

The driving machine of the present invention, which solves the above-mentioned object, has a hollow shaft into which a load shaft is inserted and a power transmission mechanism which transmits power from a power source to the hollow shaft, and in which the hollow shaft and the load shaft are fixed by fastening a hole retaining ring and a spacer or an end plate to the tip of the load shaft with a bolt, the hollow shaft has a communicating passage formed inside the hollow shaft, one end of the communicating passage opens at the tip of the hollow shaft and the other end communicates with a gap extending around the entire circumference of the shaft between the hollow shaft and the load shaft, thereby connecting the gap with the outside, and the hollow shaft and the load shaft rotate by power transmitted from the power source via the power transmission mechanism with the gap filled with grease from the outside via the communicating passage.

According to the present invention, by providing the hollow shaft with a communication passage, it is possible to arrange the open end of the communication passage in a location that is not blocked by the end plate for fixing the load shaft to the hollow shaft, or by the spacer or hole retaining ring. This makes it possible to fill the gap between the hollow shaft and the load shaft with grease through the communication passage, and the gap can be sealed with grease. This prevents rusting of the inner surface of the hollow shaft and the outer surface of the load shaft, and suppresses an increase in resistance when removing the load shaft from the hollow shaft, while making it easier to replace the grease filled to prevent rusting.

FIG. 1 is an explanatory diagram illustrating a first embodiment of a driving machine. FIG. 2 is an explanatory diagram illustrating a perspective shape of the hollow shaft of FIG. 1 . FIG. 2 is an explanatory diagram illustrating a cross section of the hollow shaft of FIG. 1 . FIG. 11 is an explanatory view illustrating a cross section of a hollow shaft of a second embodiment of a driving machine. FIG. 2 is an explanatory diagram illustrating a cross section of a hollow shaft of a reference example of a driving machine.

Below, an embodiment of the driving machine of the present invention will be described with reference to the drawings. In the drawings, the X direction is the axial direction of the hollow shaft 11, the Z direction is the vertical direction, and the Y direction is the direction perpendicular to the X and Z directions. In addition, in the drawings, the left side of the X direction is the tip side, and the right side is the end side. In the following, the inside and outside refer to the inside and outside in the axial radial direction of the hollow shaft 11.

The first embodiment of the driving machine 10 illustrated in FIG. 1 transmits power from a power source 4 to a load shaft (drive shaft, axle) 3 of a wheel 2 of a traveling device 1 arranged at the lower end of the crane structure. The crane may be any of various known cranes, including quay cranes and gantry cranes that handle containers at container terminals, and unloaders that handle bulk cargo such as iron ore and coal. The wheel 2 may be any of various known wheels, and is not limited to those with flanges that roll on rails 5, but may also be those with rubber tires that roll on the ground. The power source 4 may be any known power source such as an internal combustion engine or electric motor. The driving machine 10 is not limited to the traveling device 1 of the crane, and may also be applicable to the trolley of a crane.

The driving machine 10 can be any of various known orthogonal shaft type reducers and transmissions having a hollow shaft 11 into which the load shaft 3 is inserted. Depending on the power transmission method of the power transmission mechanism 12, the driving machine 10 can be exemplified by reducers such as parallel shaft gear reducers, helical reducers, worm reducers, bevel gear reducers, hypoid reducers, planetary gear reducers, and cycloid drive reducers, as well as transmissions such as parallel shaft gear transmissions, planetary gear transmissions, and continuously variable transmissions.

The hollow shaft 11 is fixed to the load shaft 3 by fastening a bolt 8 to the load shaft 3 via a hole retaining ring 6 and a spacer 7 arranged at the tip side. If the load shaft 3 has a step, an end plate may be used instead of the hole retaining ring 6 and the spacer 7.

The hollow shaft 11 shown in FIG. 2 has an axial direction oriented in the X direction and a cross-sectional shape in the YZ plane that is a circular ring, and the load shaft 3 is inserted into the hollow hole 13. The hollow shaft 11 has a key groove 14, a clearance groove 15, a communication passage 16, and a retaining ring groove 17.

The keyway 14 can be any of various known keyways. The keyway 14 is disposed at a position facing the keyway 9 formed on the load shaft 3 in the axial direction. The keyway 14 extends in the X direction and is recessed toward the inside or outside of the axial direction. The keyway 9 of the load shaft 3 extends in the X direction and is recessed from the outside to the inside of the axial direction. A key 20 is fitted into the keyway 9 of the load shaft 3 facing the keyway 14. By fitting the key 20, the load shaft 3 and the hollow shaft 11 are fastened, and power is efficiently transmitted between the load shaft 3 and the hollow shaft 11. The key 20 is not limited to a sunken key, and a crescent key or a sliding key is also exemplified, and the groove shape of the keyway 14 and the keyway 9 of the load shaft 3 may be any shape corresponding to the shape of the key 20. The keyway 14 is not essential, and in the case of a structure that does not use the key 20, the keyway 14 and the keyway 9 of the load shaft 3 are not formed. Additionally, the number of key grooves 14 is not limited to one, and multiple key grooves may be formed.

The escape groove 15 may be any of various known escape grooves. The escape groove 15 is located in the center of the inner peripheral surface of the hollow shaft 11 in the X direction and extends around the entire circumference in the circumferential direction of the shaft. The escape groove 15 is recessed from the inside to the outside in the radial direction of the shaft. The escape groove 15 is a groove for reducing resistance when the load shaft 3 is inserted into the hollow hole 13 of the hollow shaft 11. The escape groove 15 communicates with the key groove 14 when the key groove 14 is formed. The state in which the escape groove 15 extends around the entire circumference in the circumferential direction of the shaft also includes the case in which the escape groove 15 and the key groove 14 communicate with each other. The escape groove 15 corresponds to the gap of the present invention because it extends around the entire circumference in the circumferential direction between the hollow shaft 11 and the load shaft 3.

The communication passage 16 is formed inside the hollow shaft 11 and is a passage filled with grease. The inside of the hollow shaft 11 does not refer to the hollow hole 13, which is the inner part of the hollow shaft 11, but refers to the inside part of the annular body. The communication passage 16 communicates the escape groove 15, which is a gap that extends around the entire circumference of the shaft between the hollow shaft 11 and the load shaft 3, with the outside. In this disclosure, the outside refers to the outside of the hollow shaft 11, but is not limited to only the space around the hollow shaft 11, and also includes devices that are connected to the hollow shaft 11 excluding the load shaft 3. For example, it may be the power transmission mechanism 12. It may also be a grease supply device that can supply grease pressurized by a pump to the communication passage 16 and collect grease discharged from the communication passage 16.

At least one communication passage 16 may be formed in the hollow shaft 11, but it is preferable that multiple communication passages 16 are formed in the hollow shaft 11. The multiple communication passages 16 communicate with each other through the escape groove (gap) 15. The multiple communication passages 16 are preferably arranged at a distance from the key groove 14 in the circumferential direction of the shaft, and are also preferably arranged at a distance from each other in the circumferential direction of the shaft. The multiple communication passages 16 are preferably spaced apart from the key groove 14 in the circumferential direction of the shaft at an angle of 90 degrees or more, and are also preferably spaced apart from each other in the circumferential direction of the shaft at an angle of 90 degrees or more in the circumferential direction of the shaft. For example, one key groove 14 and two communication passages 16 may be arranged at equal intervals in the circumferential direction of the shaft. In this way, the multiple communication passages 16 communicate with each other through the escape groove 15, so that one communication passage 16 can be used for filling grease and the other communication passage 16 can be used for discharging grease. This is advantageous for ease of replacement of grease. Two or more communication passages 16 may be provided.

The communication passage 16 extends from the tip opening 18 to the end opening 19. The tip opening 18 opens on the tip surface of the hollow shaft 11. It is preferable that the tip surface of the hollow shaft 11 is a surface that does not have any equipment facing the tip surface. The tip surface of the hollow shaft 11 in this embodiment does not have any equipment facing it, and such equipment does not interfere with the filling of the grease into the communication passage 16. In addition, it is preferable that the tip opening 18 opens in the X direction (axial direction of the hollow shaft 11). If the tip opening 18 opens in a direction intersecting the X direction, the grease filled in the communication passage 16 may be scattered from the tip opening 18 to the outside due to the action of centrifugal force when the hollow shaft 11 rotates. Therefore, by having the tip opening 18 open in the X direction, it is advantageous to prevent the grease from scattering to the outside due to the action of centrifugal force when the hollow shaft 11 rotates. The end opening 19 opens on the groove bottom surface of the escape groove 15. There are no particular limitations on the location of the end opening 19, as long as it is on the bottom surface of the clearance groove 15.

The retaining ring groove 17 is a groove into which the outer periphery of the hole retaining ring 6 is fitted, and a known retaining ring groove can be used. The retaining ring groove 17 is recessed from the inside to the outside of the hollow hole 13.

3 shows the filling and discharging of grease through the communication passage 16 in the cross section of the hollow shaft 11 and the load shaft 3. In the figure, the filling of new grease is indicated by an outlined arrow, and the discharging of old grease is indicated by a filled arrow. In the grease replacement work, the grease filled in the escape groove 15 and the multiple communication passages 16 is replaced by utilizing the fact that the multiple communication passages 16 are connected to each other through the escape groove 15. First, new grease is injected from the tip opening 18 of one of the communication passages 16. Next, the injected new grease is supplied to the escape groove 15 via the communication passage 16. When the new grease is supplied, the old grease is pushed out from the escape groove 15 and discharged to the outside from the tip opening 18 of the other communication passage 16 via the other communication passage 16. The discharged old grease is collected. In this way, in the series of grease replacement work, it is not necessary to remove the hole retaining ring 6, the spacer 7, and the bolt 8.

The removal operation of the load shaft 3 from the hollow shaft 11 includes the following steps. First, the grease filled in the escape groove 15 and the communication passage 16 is washed and removed (first step). Next, a penetrating lubricant is injected from the tip opening 18 of the communication passage 16 (second step). Next, when the injected penetrating lubricant has permeated the entire area of the hollow hole 13 through the key groove 14, the escape groove 15, and the communication passage 16, the bolt 8 is released and the hole retaining ring 6 and the spacer 7 are removed. Next, the load shaft 3 is removed from the hollow shaft 11 (third step). A penetrating lubricant is a lubricant that has a higher penetrating property than grease and forms a chemical film on the metal surface. Examples of penetrating lubricants include oils that have water displacement properties and oils that have penetrating properties or rust inhibitors. Examples of penetrating lubricants include those sprayed by aerosol products. Note that if the load shaft 3 can be removed from the hollow shaft 11 without using a penetrating lubricant, the second step may be omitted.

As described above, according to this embodiment, by connecting the escape groove 15 to the outside through the communication passage 16, it is possible to inject grease into the escape groove 15 from the outside and fill the escape groove 15 with grease. This is therefore advantageous in preventing the intrusion of moisture such as rainwater or humidity into the escape groove 15 from the outside, and suppresses the occurrence of rust due to intruding moisture. As a result, it is possible to suppress an increase in resistance when removing the load shaft 3 from the hollow shaft 11.

In addition, according to this embodiment, the hollow shaft 11 has a communication passage 16, so that the tip opening 18 of the communication passage 16 can be located at a location that is not blocked by the spacer 7 or the hole retaining ring 6 for fixing the load shaft 3 to the hollow shaft 11. Therefore, the grease can be replaced without removing the spacer 7 or the hole retaining ring 6. This significantly reduces the effort required for the grease replacement work compared to a configuration in which a communication passage is formed in the load shaft 3. As a result, this embodiment is configured to prevent rusting of the inner surface of the hollow shaft 11 and the outer surface of the load shaft 3, and suppresses an increase in resistance when removing the load shaft 3 from the hollow shaft 11, while making it easier to replace the grease filled to prevent rusting.

According to this embodiment, the hollow shaft 11 is provided with multiple communication passages 16, and each communication passage 16 communicates with the other passages 16 via the escape grooves 15, making it possible to use one communication passage 16 as a supply passage for new grease and the other communication passage 16 as a discharge passage for old grease. Therefore, it is possible to periodically replace grease that deteriorates over time without removing the load shaft 3 from the hollow shaft 11, and it is possible to avoid a decrease in the rust prevention effect due to the deterioration of the grease over time. It is also possible to significantly reduce the time required for the grease replacement work.

According to this embodiment, by filling the escape groove 15 with grease, it is possible to prevent condensation from forming in the escape groove 15. This is advantageous in preventing rust caused by condensation in the escape groove 15. It is also possible to reduce galling and seizure on the inner surface of the hollow shaft 11 and the outer surface of the load shaft 3. This is advantageous in avoiding adhesion between the hollow shaft 11 and the load shaft 3 due to galling and seizure.

In addition, according to this embodiment, by filling the keyway 14 with grease, it is possible to prevent rusting between the keyways 9, 14 and the key 20. In addition, by filling the keyway 9, 14 and the key 20 with grease, it is possible to suppress fretting wear.

The second embodiment of the driving machine 10 illustrated in FIG. 4 differs from the first embodiment in that the hollow shaft 11 has a circumferential groove 21. The second embodiment also differs in that the communication passage 16 is composed of a branch passage that connects the escape groove 15 and the circumferential groove 21 to the outside.

The circumferential groove 21 extends in the circumferential direction of the shaft and is recessed outward from the inner peripheral surface of the hollow hole 13 of the hollow shaft 11. The circumferential groove 21 is preferably disposed at the end of the hollow hole 13 in the X direction, and more preferably disposed at the end where the hole retaining ring 6 and spacer 7 are not disposed, rather than at the tip where the hole retaining ring 6 and spacer 7 are disposed. It is even more preferable that the circumferential groove 21 is disposed at both the tip and end of the hollow hole 13. When the circumferential grooves 21 are disposed at both the tip and end of the hollow hole 13, it is preferable that each of the circumferential grooves 21 is disposed as close as possible to the tip or end, and that the distance between the circumferential grooves 21 in the X direction is close to the length of the hollow hole 13 in the X direction.

The circumferential groove 21 may communicate with the keyway 14, but may not communicate with the keyway 14 depending on the extension state of the keyway 14 in the X direction. When the circumferential groove 21 communicates with the keyway 14, it forms an ended C-shaped ring, and when it does not communicate with the keyway 14, it forms an endless O-shaped ring. The depth (depth in the axial radial direction) of the circumferential groove 21 is preferably shallower than the depth of the keyway 14, and the groove width of the circumferential groove 21 is also preferably narrower than the groove width of the keyway 14. If the depth of the circumferential groove 21 is shallower than 0.5% of the diameter of the hollow hole 13 of the hollow shaft 11, the injection resistance increases when supplying grease, and it becomes impossible to supply it sufficiently. On the other hand, if the depth of the circumferential groove 21 is deeper than 3.0% of the diameter of the hollow hole 13, the time required for processing is extended, and the circumferential groove 21 acts as a notch, reducing the torque transmission capacity and strength of the hollow shaft 11. Therefore, the depth of the circumferential groove 21 is preferably in the range of 0.5% to 3.0% of the diameter of the hollow hole 13. In this disclosure, the range of 0.5% to 3.0% includes 0.5% and 3.0%. The circumferential groove 21 extends around the entire circumference in the axial direction between the hollow shaft 11 and the load shaft 3, and corresponds to the gap in the present invention.

The communication passage 16 is composed of a branch passage that connects both the escape groove 15 and the circumferential groove 21 to the outside. The communication passage 16 has a plurality of end openings 19, each of which opens into the bottom of the escape groove 15 and the circumferential groove 21.

In the driving machine 10 of this embodiment, the communication passage 16 allows grease to be injected from the outside into the circumferential groove 21 in addition to the escape groove 15. Therefore, the grease filled in the circumferential groove 21 can prevent moisture from entering. For example, if the circumferential groove 21 is arranged only at the end of the hollow hole 13, it is advantageous to prevent moisture such as rainwater and humidity from entering from the end side of the hollow hole 13. The tip of the hollow hole 13 is prevented to some extent by the spacer 7 from the tip side of moisture such as rainwater and humidity. In this way, by providing the circumferential groove 21 at the end side, it is possible to suppress the occurrence of rust due to moisture that has entered on the inner surface of the hollow shaft 11 and the majority of the outer surface of the load shaft 3, and to prevent rusting. In addition, if the circumferential groove 21 is arranged at both ends of the hollow hole 13, it is possible to further prevent moisture from entering the part sandwiched between the multiple circumferential grooves 21. Accordingly, it is possible to suppress an increase in resistance when removing the load shaft 3 from the hollow shaft 11.

Although the embodiments of the present disclosure have been described above, the driving machine of the present disclosure is not limited to a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present disclosure.

The driving machine 10 may be integrated with the power source 4. As the driving machine 10 and the power source 4 integrated together, various known motors with reducers or geared motors can be used. Furthermore, the driving machine 10 is not limited to one that transmits power to the wheels 2 of the traveling device 1 of the crane. The driving machine 10 is particularly suitable for use in equipment that is installed outdoors and exposed to rainwater, etc.

When using an end plate to fix the hollow shaft 11 and the load shaft 3, it is desirable to ensure that the end plate does not block the entire tip surface of the hollow shaft 11. For example, a hole that communicates with the tip opening 18 may be formed at a position corresponding to the tip opening 18 of the communication passage 16 of the end plate.

When the circumferential groove 21 is formed, the communication passage 16 may communicate only with the circumferential groove 21. Since the circumferential groove 21 on the outer side of the clearance groove 15 is filled with grease to prevent moisture from entering the clearance groove 15, the communication passage 16 does not need to communicate with the clearance groove 15.

The relief groove 15 may be formed in either the hollow shaft 11 or the load shaft 3, and may be formed in the load shaft 3. When the relief groove 15 is formed in the load shaft 3, the relief groove 15 extends around the entire circumference in the axial direction and is recessed inward from the outer circumferential surface of the load shaft 3. Similarly, the circumferential groove 21 may be formed in the load shaft 3. When the relief groove 15 or the circumferential groove 21 is formed in the load shaft 3, the end opening 19 of the communication passage 16 opens to the inner circumferential surface of the hollow hole 13 at a position corresponding to the relief groove 15 or the circumferential groove 21 formed in the load shaft 3.

When the escape groove 15 and the communication passage 16 are filled with grease, the communication passage 16 may have the tip opening 18 open, or the tip opening 18 may be sealed with a plug or the like. The plug may be any of a variety of known grease nipples.

The driving machine 10 is not limited to a key type in which the power transmission method between the hollow shaft 11 and the load shaft 3 uses a key groove 14 and a key 20, but may also use a friction fastening method. Examples of friction fastening methods include a wedge type such as a shrink disk, a clamping sleeve type, and a hydro type. The friction fastening method is less susceptible to fretting wear than the key type. Therefore, the friction fastening method is advantageous in avoiding adhesion that uses wear powder caused by fretting wear as a medium.

The reference example of the driving machine 10 illustrated in FIG. 5 differs from the first embodiment in that grease is not filled. In the escape groove extending in the circumferential direction of the shaft between the hollow shaft and the load shaft in the conventional technology, moisture caused by rainwater or humidity that has entered from the end side or condensation that has formed in the escape groove continues to accumulate, causing rust on the inner surface of the hollow shaft and the outer surface of the load shaft. In the course of developing the present invention, the inventors of the present invention discovered that by ensuring the breathability of the escape groove, rust caused by moisture accumulated in the escape groove can be suppressed. The reference example is based on that knowledge.

The escape groove 15 and the communication passage 16 of the drive unit 10 of the reference example are not filled with grease, so that rainwater or moisture may enter the escape groove 15 from the outside, or condensation may occur in the escape groove 15. The moisture present in the escape groove 15 evaporates over time and is released to the outside because the escape groove 15 is connected to the outside by the communication passage 16. In this way, even if the escape groove 15 and the communication passage 16 are not filled with grease, the escape groove 15 and the outside are connected by the communication passage 16, which improves ventilation and is advantageous in preventing rust caused by moisture remaining in the escape groove 15 for a long period of time. To ensure ventilation, it is desirable to provide multiple communication passages 16. In addition, since the escape groove 15 and the communication passage 16 are not filled with grease, the opening that serves as the entrance and exit of the communication passage 16 to the outside may be disposed on the end surface of the hollow shaft 11 or on the outer circumferential surface of the hollow shaft 11.

It has been found that wear particles due to fretting wear are small and oxidation progresses rapidly at high temperatures. Therefore, in the reference example, wear particles due to fretting wear of the hollow shaft 11 and the load shaft 3, or the keyway 14 and the key 20, act as a medium, making it easy for the hollow shaft 11 and the load shaft 3 to stick together. In contrast, the embodiment described above is more preferable because the grease filled in prevents sticking caused by wear particles due to fretting wear. However, when the power transmission method between the hollow shaft 11 and the load shaft 3 is a friction fastening method, wear particles due to fretting wear are less likely to be generated, and in some cases, it may be possible to sufficiently prevent sticking of the hollow shaft 11 and the load shaft 3 even in the reference example.

Reference Signs List 3: Load shaft 4: Power source 10: Driving machine 11: Hollow shaft 12: Power transmission mechanism 13: Hollow hole 14: Key groove 15: Relief groove 16: Communication passage 20: Key 21: Circumferential groove

Claims (6)

A driving machine having a hollow shaft into which a load shaft is inserted and a power transmission mechanism for transmitting power from a power source to the hollow shaft, in which the hollow shaft and the load shaft are fixed by fastening a hole retaining ring and a spacer or an end plate to the tip of the load shaft with a bolt, wherein the hollow shaft has a communicating passage formed inside the hollow shaft, one end of the communicating passage opens at the tip of the hollow shaft and the other end communicates with a gap extending around the entire circumference of the shaft between the hollow shaft and the load shaft, thereby connecting the gap with the outside, and the hollow shaft and the load shaft rotate by power transmitted from the power source via the power transmission mechanism with the gap filled with grease from the outside via the communicating passage. The drive machine of claim 1, which is provided with a plurality of communication passages, each of which communicates with the other through the gap. The drive unit according to claim 1 or 2, wherein the gap is configured as a relief groove for reducing resistance when the load shaft is inserted into the hollow hole of the hollow shaft. The drive unit according to claim 1 or 2, wherein the gap is composed of an escape groove for reducing resistance when the load shaft is inserted into the hollow hole of the hollow shaft, and a circumferential groove disposed axially outward of the escape groove and recessed in the radial direction of the shaft. The drive unit according to claim 1 or 2, wherein the gap is disposed at the axial end of the hollow hole of the hollow shaft and is configured as a circumferential groove recessed in the radial direction of the shaft. The drive machine according to claim 1 or 2, wherein the gap communicates with keyways formed in the load shaft and the hollow shaft.

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