Gearmotor

Abstract

In a variable speed motor (100), a spline portion (32) is formed at an end of a drive shaft (31) of a transmission (30), a spline hole (22) which engages with the spline portion (32) is formed at an end face (21a) of a motor shaft (21) of an oil pressure motor (20), and a snap ring (33) is provided at an outer periphery of the drive shaft (31) formed with the spline portion (32), the snap ring (33) abutting against the end face (21a) of the motor shaft (21) formed with the spline hole (22) and positioning the motor shaft (21) and the drive shaft (31).

Description

Technical Field

[0001] This invention relates to a motor with a gearbox. Background Technology

[0002] Japanese Patent Application Publication No. JP1995-28440Y discloses a reducer motor with a planetary gear mechanism on the output side of a hydraulic motor. In this reducer motor, the input side component of the reducer assembly with the planetary reduction mechanism, i.e., the input shaft, is connected to the motor shaft of the hydraulic motor. Summary of the Invention

[0003] In the motor with a speed reducer described in Japanese Patent Application Publication JP1995-28440Y, the input shaft of the planetary speed reducer is inserted into a recess formed on the end face of the motor shaft of the hydraulic motor and connected to the motor shaft of the hydraulic motor. The input shaft of the speed reducer and the motor shaft of the hydraulic motor are axially positioned by the top surface of the input shaft abutting against the bottom surface of the recess on the motor shaft of the hydraulic motor.

[0004] In the above structure, to ensure the positioning accuracy of the input shaft of the reduction mechanism and the motor shaft of the hydraulic motor, the top surface of the input shaft of the reduction mechanism and the bottom surface of the recess formed on the motor shaft of the hydraulic motor need to be machined with high precision to be flat surfaces. However, machining the bottom surface of the recess generally requires inserting tools into the recess, which is complicated and may increase manufacturing costs.

[0005] The purpose of this invention is to reduce the manufacturing cost of motors with gearboxes.

[0006] According to one aspect of the present invention, a motor with a gearbox has an engaging portion formed at one end of the motor shaft of the motor and the drive shaft of the gearbox, and an engaging recess formed on the end face of the other end of the motor shaft and the drive shaft, which engages with the engaging portion. An abutting portion is provided on the outer periphery of one of the motor shaft and the drive shaft for which the engaging portion is formed, and the abutting portion abuts against the end face of the other motor shaft and the drive shaft for which the engaging recess is formed, thereby positioning the motor shaft and the drive shaft. Attached Figure Description

[0007] Figure 1 This is a cross-sectional view of a hydraulic motor with a transmission according to an embodiment of the present invention.

[0008] Figure 2 This is a cross-sectional view showing the connection structure between the motor shaft of the motor and the drive shaft of the transmission according to an embodiment of the present invention.

[0009] Figure 3 This is a cross-sectional view illustrating the connection structure between the motor shaft of the motor and the drive shaft of the transmission according to a modified embodiment of the present invention. Detailed Implementation

[0010] Hereinafter, with reference to the accompanying drawings, the motor 100 with a gearbox according to an embodiment of the present invention will be described.

[0011] The transmission motor 100 is used in a travel motor that is installed in the axle of a tracked machine, such as a hydraulic excavator, and drives the track.

[0012] like Figure 1 As shown, the motor 100 with a gearbox includes a housing 1, a hydraulic motor 20 (motor) as a drive source, and a gearbox 30 for changing the output rotation of the motor shaft 21 of the hydraulic motor 20.

[0013] The outer casing 1 includes a fixed outer casing 10 and a cylindrical rotating outer casing 15 that rotates relative to the fixed outer casing 10. A sprocket (not shown) is connected to the outer peripheral surface of the rotating outer casing 15. By rotating the rotating outer casing 15 and the sprocket together, the vehicle moves in a cyclic manner through a track (not shown) that meshes with the sprocket.

[0014] The fixed housing 10 and the rotating housing 15 are disposed inside the path of the track circulation. The rotating housing 15 is supported by bearings 3 in a manner that allows it to rotate freely relative to the fixed housing 10, which is connected to the vehicle body 101 as an external component, and rotates around the central axis.

[0015] The fixed housing 10 has a fixed flange portion 12 that is formed in a manner that protrudes from the outer peripheral surface of the main body portion 11 and is mounted on the vehicle body 101.

[0016] A disc-shaped opening end cap 17 is installed on the inner periphery of the opening end 15a of the rotating housing 15 in a detachable manner to close the opening end 15a.

[0017] The gear chamber 4, which houses the transmission mechanism 40 described later, is divided by the inner surface of the rotating outer casing 15, the outer surface of the main body 11 of the fixed outer casing 10, and the open end cap 17. The gear chamber 4 is filled with lubricating oil for lubricating the transmission mechanism 40.

[0018] A rotating flange portion 16 is formed on the rotating housing 15, protruding annularly from the outer peripheral surface. The sprocket is connected to the rotating flange portion 16 by a plurality of bolts (not shown) and rotates together with the rotating housing 15.

[0019] A floating seal 5 is provided between the fixed housing 10 and the rotating housing 15. The floating seal 5 seals the transmission 30 so that the working oil inside the transmission 30 does not leak to the outside when the rotating housing 15 rotates, and also prevents foreign objects from entering the transmission 30 from the outside.

[0020] Furthermore, a labyrinth seal 6 is formed between the fixed housing 10 and the rotating housing 15. This labyrinth seal 6 prevents foreign objects such as mud from entering the outside of the floating seal 5. The labyrinth seal 6 is formed by the gap between the opposing end faces of the fixed housing 10 and the rotating housing 15.

[0021] The hydraulic motor 20 is housed inside the body portion 11 of the fixed housing 10. The hydraulic motor 20 is, for example, a swashplate piston motor that drives the motor shaft 21 to rotate via the supply and discharge of working oil (working fluid). Alternatively, the motor may be a motor other than the hydraulic motor 20; for example, an electric motor may be used. Since the hydraulic motor 20 can adopt a known structure, therefore, in Figure 1 The diagram is simplified by omitting the motor shaft 21, and detailed descriptions are omitted in this specification.

[0022] The transmission 30 includes: a drive shaft 31, which is coaxially connected to the motor shaft 21 of the hydraulic motor 20 and transmits the rotation of the motor shaft 21; and a transmission mechanism 40, which is housed inside the rotating housing 15 and performs speed changes on the drive shaft 31.

[0023] This transmission 40 is a planetary gear mechanism. The transmission mechanism 40 includes: a sun gear 41 mounted on the drive shaft 31; an internal gear 42 mounted on the inner wall of the rotating housing 15; multiple planetary gears 43 meshing with both the sun gear 41 and the internal gear 42; a planetary carrier 44 supporting each planetary gear 43; a second-stage sun gear 45 meshing with the planetary carrier 44; and multiple planetary gears 46 meshing with both the sun gear 45 and the internal gear 42. The transmission mechanism 40 changes the speed of the output rotation of the motor shaft 21 of the hydraulic motor 20, which is transmitted via the drive shaft 31, and transmits this rotation to the rotating housing 15.

[0024] Next, refer to Figure 2 The connection structure between the motor shaft 21 of the hydraulic motor 20 and the drive shaft 31 of the transmission 30 will be explained.

[0025] The motor shaft 21 and the drive shaft 31 are coaxially connected to each other via a spline connection. Thus, when the motor shaft 21 of the hydraulic motor 20 is rotated, the drive shaft 31 also rotates along with the motor shaft 21. Furthermore, the connection between the motor shaft 21 and the drive shaft 31 is not limited to a spline connection; any structure can be used as long as the drive shaft 31 rotates along with the motor shaft 21.

[0026] like Figure 2 As shown, at the end of the drive shaft 31 on the side of the hydraulic motor 20, a spline portion 32 with spline teeth 32a formed on its outer periphery is provided as an engaging portion. Furthermore, the end face (hereinafter referred to as "top face 31a") of the end of the drive shaft 31 on the side of the hydraulic motor 20 is formed as a flat surface perpendicular to the central axis of the drive shaft 31. The top face 31a of the drive shaft 31 is a surface (opposing surface) opposite to the motor shaft 21.

[0027] On the end face of the motor shaft 21 on the drive shaft 31 side (hereinafter also referred to as "top face 21a"), a spline hole 22 is formed as a locking recess for the end of the drive shaft 31 to be inserted, and a spline groove 22a is formed on its inner circumference. The spline hole 22 is a circular hole with a bottom surface 22b. The top face 21a of the motor shaft 21 and the bottom surface 22b of the spline hole 22 are flat surfaces perpendicular to the motor shaft 21. In addition, the top face 21a is a surface opposite to the drive shaft 31 (opposing surface).

[0028] The drive shaft 31 and the motor shaft 21 are connected by engaging the splined portion 32 of the drive shaft 31 with the splined hole 22 of the motor shaft 21 (spline engagement).

[0029] An annular mounting groove 31b is formed on the outer periphery of the drive shaft 31, specifically on the outer periphery of the incomplete portion 32b of the spline portion 32. A retaining ring 33, protruding radially outward from the drive shaft 31 and serving as an annular abutment portion, is provided in the mounting groove 31b. The retaining ring 33 is detachably mounted in the mounting groove 31b of the drive shaft 31. Furthermore, the incomplete portion 32b (incomplete spline portion) of the spline portion 32 refers to the portion formed by machining the spline teeth 32a that does not function as a spline, and corresponds to the boundary between the spline teeth 32a and the portion where the spline teeth 32a are not formed. Figure 2 In the diagram, the incomplete part 32b is indicated by a double-dotted line and an arrow.

[0030] The outer diameter of the retaining ring 33 is set such that, when mounted on the outer periphery of the drive shaft 31, it is larger than the inner diameter of the spline hole 22 of the motor shaft 21, and smaller than the outer diameter of the end of the motor shaft 21. Furthermore, the outer diameter of the retaining ring 33, when mounted on the outer periphery of the drive shaft 31, is formed to be flush with the sun gear 45 (see reference 45). Figure 1The inner diameter of the drive shaft 31 is relatively small. Therefore, even with the retaining ring 33 installed, the drive shaft 31 can be inserted into the inner circumference of the sun gear 45, thus improving the assemblability of the transmission 30.

[0031] The splined portion 32 of the drive shaft 31 is inserted into the splined hole 22 of the motor shaft 21 until the retaining ring 33 abuts against the top surface 21a of the motor shaft 21. By abutting the retaining ring 33 against the top surface 21a of the motor shaft 21, the drive shaft 31 and the motor shaft 21 are axially positioned. Axial positioning of the drive shaft 31 and the motor shaft 21 by the retaining ring 33 ensures the engagement length of the splined connection and prevents stress concentration caused by insufficient engagement length, thereby ensuring durability.

[0032] With the retaining ring 33 abutting against the top surface 21a of the motor shaft 21, the top surface 31a of the drive shaft 31 and the bottom surface 22b of the spline hole 22 of the motor shaft 21 are not in contact with each other, but rather in the transverse direction of the motor shaft 21 (drive shaft 31). Figure 2 Separated in the left-right direction. As a result, a gap is formed between the top surface 31a of the drive shaft 31 and the bottom surface 22b of the spline hole 22.

[0033] Here, to position the drive shaft and motor shaft axially, it's also possible to forgo the use of retaining rings and instead have the top surface of the drive shaft, inserted into the splined hole, abut against the bottom surface of the splined hole. In this case, to ensure positioning accuracy, both the top surface of the drive shaft and the bottom surface of the splined hole need to be machined (finished) with high precision and flatness. However, machining the surface of the splined hole requires inserting a tool into it, which is cumbersome. Furthermore, machining the bottom surface of the splined hole, such as machining the outer circumference of the motor shaft or the spline groove of the splined hole, requires changes in settings such as tool changes and changes in the mounting posture of the workpiece (motor shaft) on the machine tool (re-clamping), making it impossible to perform continuously without setting changes. Therefore, machining the bottom surface of the splined hole increases manufacturing time and may increase the manufacturing cost of the motor with the gearbox.

[0034] In this embodiment, the drive shaft 31 and the motor shaft 21 are positioned by abutting against the top surface 21a of the motor shaft 21 using a retaining ring 33 disposed on the outer periphery of the drive shaft 31. Therefore, the top surface 31a of the drive shaft 31 and the bottom surface 22b of the spline hole 22 of the motor shaft 21 are separated without contact. This eliminates the need for finishing machining the bottom surface 22b of the spline hole 22 into a flat surface. Furthermore, the machining of the retaining ring 33 and the top surface 21a of the motor shaft 21 can be performed more easily than machining the bottom surface 22b of the spline hole 22. Therefore, in this embodiment, the manufacturing process of the gearbox motor 100 can be simplified.

[0035] According to the above implementation method, the following effects are achieved.

[0036] In the gearbox motor 100, the motor shaft 21 of the hydraulic motor 20 and the drive shaft 31 of the gearbox 30 are positioned by abutting against the top surface 21a of the motor shaft 21 through a retaining ring 33 provided on the outer periphery of the drive shaft 31. This eliminates the need for the bottom surface 22b of the spline hole 22 formed in the motor shaft 21 to abut against the top surface 31a of the drive shaft 31 for positioning the motor shaft 21 and the drive shaft 31. Therefore, the finishing of the bottom surface 22b of the spline hole 22 to ensure accuracy can be omitted. Consequently, the manufacturing cost of the gearbox motor 100 can be reduced.

[0037] Furthermore, the finishing of the bottom surface 22b of the spline hole 22 can be omitted, and consequently, the finishing of the top surface 31a of the drive shaft 31 is also unnecessary. Therefore, the end of the drive shaft 31, including the spline hole 22 and the spline portion 32, is not formed by machining, but can be formed by plastic forming such as forging, thereby improving the material yield and further reducing the manufacturing cost of the gearbox motor 100. Alternatively, the drive shaft 31 can also be machined.

[0038] Furthermore, a retaining ring 33 is provided on the outer periphery of the incomplete portion 32b of the spline portion 32 of the drive shaft 31. This allows for miniaturization of the geared motor 100 in the axial direction of the motor shaft 21 compared to the case where the retaining ring 33 is provided on the outer periphery of the portion of the drive shaft 31 where the spline portion 32 is not formed. Additionally, since the retaining ring 33 is provided on the incomplete portion 32b where it does not function as a spline (not engaging with the spline groove 22a), the axial area occupied by the incomplete portion 32b can be effectively utilized, thereby enabling miniaturization of the geared motor 100 in the axial direction while ensuring the engagement length of the spline connection. Furthermore, by providing the retaining ring 33 on the incomplete portion 32b, it is possible to prevent the spline groove 22a on the inner periphery of the spline hole 22 from engaging with the incomplete portion 32b.

[0039] Next, variations of this embodiment will be described. The following variations are also within the scope of this invention, and it is possible to combine the structures shown in the variations with the structures described in the above embodiments, or to combine the structures described in the following different variations with each other.

[0040] In the above embodiment, the retaining ring 33 is disposed on the outer periphery of the incomplete portion 32b of the spline portion 32; however, this structure is not mandatory. The retaining ring 33 may also be disposed in a position opposite to the motor shaft 21 and away from the spline portion 32. Furthermore, the retaining ring 33 may also be disposed on the outer periphery of the spline portion 32 if the engagement length between the spline portion 32 and the spline hole 22 can be sufficiently ensured. However, when the retaining ring 33 is disposed in a position opposite to the motor shaft 21 and away from the spline portion 32, the motor shaft 21 and drive shaft 31 need to be configured to be relatively long according to this structure. Therefore, in order to miniaturize the motor 100 with a gearbox in the axial direction, it is preferable to dispose of the retaining ring 33 closer to the spline portion 32; by disposing of it on the outer periphery of the incomplete portion 32b as described above, further miniaturization in the axial direction can be achieved.

[0041] Furthermore, in the above embodiment, the abutment portion is a retaining ring 33 that is detachably provided on the outer periphery of the drive shaft 31. That is, in the above embodiment, the abutment portion is configured to be separate from the drive shaft 31. In contrast, as... Figure 3 As shown, the abutment portion can also be an annular protrusion 133 formed integrally with the drive shaft 31 and protruding radially outward from the outer periphery of the drive shaft 31. According to this variation, since there is no possibility of forgetting to install the retaining ring, the abutment portion can be reliably abutted against the motor shaft 21 of the hydraulic motor 20. Even when the abutment portion is a protrusion 133, it is preferable to provide the protrusion 133 at the location of the incomplete portion 32b of the spline portion 32; however, this is not a limitation, and the protrusion 133 can also be provided in the spline portion 32 or in areas of the drive shaft 31 where the spline portion 32 is not provided.

[0042] Furthermore, in the above embodiment, a spline portion 32 is formed on the drive shaft 31 of the transmission 30, and a spline hole 22 is formed on the motor shaft 21 of the hydraulic motor 20. That is, the drive shaft 31 is configured as an external spline, and the motor shaft 21 is configured as an internal spline. In contrast, the spline connection structure can also be configured in the opposite way to the above embodiment. That is, a spline portion 32 serving as an engagement portion can be formed on the motor shaft 21 of the hydraulic motor 20, and a spline hole 22 serving as an engagement recess can be formed on the top surface 31a of the drive shaft 31 of the transmission 30. In this case, simply providing an abutment portion (a retaining ring 33, a protrusion 133) on the motor shaft 21 where the engagement portion is formed, and abutting the abutment portion against the top surface 31a of the drive shaft 31, can position the motor shaft 21 and the drive shaft 31. Even in this modified example, the same effect as the above embodiment is achieved.

[0043] Furthermore, although the transmission mechanism 40 is a planetary gear mechanism in the above embodiment, it is not limited to this. The transmission mechanism 40 can be other gear mechanisms, or it can be constructed by combining multiple gear mechanisms.

[0044] The structure, function, and effects of the embodiments of the present invention are summarized and explained below.

[0045] The motor 100 with a gearbox includes: a hydraulic motor 20 that drives a motor shaft 21 to rotate; and a gearbox 30 that has a drive shaft 31 connected to the motor shaft 21 and outputs the rotational speed of the motor shaft 21 transmitted via the drive shaft 31. A engaging portion (spline portion 32) is formed at the end of one of the motor shaft 21 of the hydraulic motor 20 and the drive shaft 31 of the gearbox 30, and an engaging recess (spline hole 22) is formed on the end face of the other end to engage with the engaging portion. An abutment portion (retaining ring 33, protrusion 133) is provided on the outer periphery of one of the motor shaft 21 and the drive shaft 31 for which the engaging portion is formed. The abutment portion (retaining ring 33, protrusion 133) abuts against the end face 21a of the other end of the motor shaft 21 and the drive shaft 31 for which the engaging recess is formed, and positions the motor shaft 21 and the drive shaft 31.

[0046] In addition, in the motor 100 with a gearbox, the abutment part is a retaining ring 33 that is installed on the outer periphery of one of the motor shaft 21 and the drive shaft 31 in a detachable manner.

[0047] In the above structure, the motor shaft 21 of the hydraulic motor 20 and the drive shaft 31 of the transmission 30 are positioned by abutting a portion provided on the outer periphery of one and the end face of the other. This eliminates the need for the bottom surface 22b of the engagement recess formed in the motor shaft 21 and drive shaft 31 to abut against one of them for positioning. Therefore, machining the bottom surface 22b of the engagement recess to ensure accuracy can be omitted. Consequently, the manufacturing cost of the transmission motor 100 can be reduced.

[0048] In addition, in the modified example of the motor 100 with a gearbox, the abutment portion is a protrusion 133 that is formed integrally with the drive shaft 31 and protrudes radially outward from the outer periphery of the drive shaft 31.

[0049] In this structure, since the possibility of forgetting to install the abutment part on the retaining ring 31 is not overlooked, the abutment between the motor shaft 21 and the abutment part (protrusion 133) can be reliably implemented.

[0050] In addition, in the motor 100 with a gearbox, the engaging part is a splined part 32 formed on the outer periphery of one of the motor shaft 21 and the drive shaft 31, and the abutting part is provided on the outer periphery of the incomplete part 32b of the splined part 32.

[0051] In this structure, the motor 100 with a gearbox can be miniaturized in the axial direction of the motor shaft 21 while ensuring the spline connection length.

[0052] The embodiments of the present invention have been described above. However, the above embodiments are merely some examples of the application of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the above embodiments.

Claims

1. A belt-drive motor comprising: a motor that rotationally drives a motor shaft; a transmission that has a drive shaft coupled to the motor shaft and that changes the rotation of the motor shaft transmitted via the drive shaft and outputs, a fitting portion is formed at an end portion of one of the motor shaft and the drive shaft, and a fitting recess that fits with the fitting portion is formed at an end surface of the other; a contact portion is provided at an outer periphery of the one of the motor shaft and the drive shaft on which the fitting portion is formed, the contact portion abuts against the end surface of the other of the motor shaft and the drive shaft on which the fitting recess is formed and performs positioning in an axial direction of the motor shaft and the drive shaft; the fitting portion is a spline portion formed at the outer periphery of the one of the motor shaft and the drive shaft; the contact portion is provided at an incomplete outer periphery of the spline portion; the incomplete outer periphery is a portion that is formed by machining of a spline tooth and does not function as a spline, and is a portion of a boundary between the spline tooth and a portion in which the spline tooth is not formed.

2. The belt-drive motor according to claim 1, wherein the contact portion is a snap ring that is detachably attached to the outer periphery of the one of the motor shaft and the drive shaft.

3. The belt-drive motor according to claim 1, wherein the contact portion is a protruding portion that is integrally formed with the one of the motor shaft and the drive shaft and protrudes from the outer periphery of the one of the motor shaft and the drive shaft to a radially outer side. ​ ​ ​ ​ ​ ​ ​ ​ ​

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