JP7227815B2 - power transmission device - Google Patents

Description

The present invention relates to power transmission devices.

BACKGROUND ART A power transmission device that decelerates and outputs the rotation of a hydraulic motor for driving a crawler type travel device is known (see Patent Documents 1 and 2).

The power transmission device described in Patent Document 1 includes a motor housing 61 that houses a hydraulic motor 47, a rotating drum 62 that is rotatably supported by the motor housing 61, and a rotational output of the hydraulic motor 47 housed in the rotating drum 62. and a deceleration device 63 for decelerating and transmitting to the rotating drum 62 . The rotating drum 62 is rotatably supported by the motor housing 61 via a bearing 91 (see paragraph [0042] of Patent Document 1, FIG. 1).

In the power transmission device described in Patent Document 2, a speed reducer main body 16 having an internal gear 29 is rotatably supported by bearings 15 on the outer wall of a casing 14 of a hydraulic motor 11 (paragraph of Patent Document 2). [0008], see FIG. 1).

JP 2009-299531 A JP 2016-164423 A

In the power transmission device described in Patent Document 1, as shown in FIG. It regulates the axial movement of the rotating drum 62 . However, in the configuration described in Patent Document 1, it is necessary to perform hole processing for forming a slot for charging the spheres from the outside of the drum main body 89 of the rotary drum 62. Since it is necessary to appropriately manage the number of spheres as well as throwing in one, there is a problem that manufacturing takes time and effort.

In the power transmission device described in Patent Document 2, as shown in FIG. 1 of Patent Document 2, an annular member having a rectangular cross section is interposed between a pair of bearings 15. The axial movement of the reduction gear main body 16 with respect to is regulated. However, in the configuration in which the annular members are brought into contact with the pair of bearings 15, there is a risk that the bearings 15 may loose if there is a large manufacturing error in the thickness (length in the axial direction) of the annular members.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to suppress backlash of a bearing without increasing manufacturing costs.

The present invention is a power transmission device comprising a fixed housing that houses a drive source, a rotary housing that rotates by transmitting the output rotation of the drive source, and a rotary housing that is attached to the fixed housing and rotates the rotary housing with respect to the fixed housing. Equipped with a pair of bearings that are freely supported, and a retaining ring with a circular cross section that restricts relative movement of the bearings and the rotating housing in the axial direction. A chamfered portion is formed at the outer peripheral corner portion of each outer ring on the side of the other bearing, and the first concave portion formed on the inner circumference of the rotary housing abuts against the outer rings of the pair of bearings to form the respective chamfered portions. A retaining ring is disposed in a space surrounded by a second recess formed by and.

In this invention, since the snap ring is arranged in the space surrounded by the first recess formed in the inner periphery of the rotating housing and the second recess formed by the contact of the outer rings of the pair of bearings, It is possible to prevent the rotary housing from falling off from the stationary housing without increasing the manufacturing cost. In addition, since the outer rings of the pair of bearings abut each other, the accumulated tolerance can be reduced and looseness can be suppressed compared to the case where a separate member is interposed between the outer rings of the pair of bearings. That is, according to the present invention, it is possible to suppress looseness of the bearing without increasing the manufacturing cost.

The present invention further comprises a speed change mechanism housed in the rotary housing, which shifts the output rotation of the drive source and transmits it to the rotary housing, and a floating seal which seals a gap between the fixed housing and the rotary housing. A seal comprises: a first elastic ring provided on the stationary housing; a first seal ring supported by the stationary housing via the first elastic ring; a second elastic ring provided on the rotary housing; a second seal ring supported by the rotary housing and in sliding contact with the first seal ring.

In the present invention, it is possible to suppress deterioration of the sealing performance between the first seal ring and the second seal ring of the floating seal by suppressing the positional deviation between the fixed housing and the rotating housing.

ADVANTAGE OF THE INVENTION According to this invention, the backlash of a bearing can be suppressed, without causing an increase in manufacturing cost.

FIG. 1 is a cross-sectional view of a driving device provided with a power transmission device according to an embodiment of the invention. FIG. 2 is a partial cross-sectional view showing an enlarged portion II of FIG. FIG. 3 is a schematic diagram for explaining the assembly procedure of the bearing unit.

A power transmission device according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a power transmission device that transmits power of a hydraulic motor, which is a drive source for traveling of a crawler work machine such as a hydraulic excavator, to a crawler belt will be described as an example. FIG. 1 is a cross-sectional view of a driving device 1 including a power transmission device 100, and FIG. 2 is a partial cross-sectional view showing an enlarged part II of FIG.

As shown in FIG. 1, the drive device 1 includes a hydraulic motor 9 as a drive source and a power transmission device 100 that transmits the power of the hydraulic motor 9 to a crawler belt (not shown). The power transmission device 100 includes a fixed housing 10 that houses a hydraulic motor 9 , a rotary housing 20 that is rotatably provided with respect to the fixed housing 10 , and a shaft 31 of the hydraulic motor 9 that changes the speed of output rotation to the rotary housing 20 . and a transmission mechanism 30 for transmission.

The rotary housing 20 is a cylindrical member and accommodates a transmission mechanism 30 therein. The rotation housing 20 is rotated by transmission of the output rotation of the hydraulic motor 9 via the transmission mechanism 30 .

The fixed housing 10 and the rotary housing 20 are arranged inside the path along which the crawler belt circulates. The rotary housing 20 is formed with an annular rotary flange 29 protruding radially outward from the outer peripheral surface 22 . A sprocket (not shown) is fastened to the rotary flange 29 with bolts. A crawler belt meshes with the sprocket. When the rotating housing 20 and the sprocket rotate together, the crawler belt meshing with the sprocket circulates and the crawler type working machine travels.

The power transmission device 100 includes a bearing unit 40 provided between the outer circumference of the fixed housing 10 and the inner circumference of the rotary housing 20 . The bearing unit 40 includes a pair of bearings 41 that rotatably support the rotary housing 20 with respect to the fixed housing 10, a snap ring 49 that restricts axial relative movement between the bearings 41 and the rotary housing 20, and have

The rotary housing 20 is rotatably supported via a pair of bearings 41 with respect to the fixed housing 10 fixed to the vehicle body 6 as an external member, and rotates about the rotation center axis O. As shown in FIG. The details of the mounting structure of the bearing unit 40 composed of the pair of bearings 41 and the snap ring 49 will be described later.

The hydraulic motor 9 is housed inside the body portion 11 of the fixed housing 10 . The hydraulic motor 9 is, for example, a swash plate type piston motor. The drive source may be other than the hydraulic motor, for example, the drive source may be an electric motor. A fixed flange 12 is formed on the fixed housing 10 so as to protrude from the outer peripheral surface of the body portion 11 . The fixed housing 10 is fixed to the vehicle body 6 by attaching the fixed flange 12 to the vehicle body 6 with bolts.

The transmission mechanism 30 according to this embodiment is a planetary gear reduction mechanism that reduces the output rotation of the shaft 31 of the hydraulic motor 9 and transmits it to the rotary housing 20 . The transmission mechanism 30 includes a sun gear 32 provided on the shaft 31 of the hydraulic motor 9, an inner gear 33 provided on the inner wall of the rotary housing 20, a plurality of planetary gears 34 meshing with both the sun gear 32 and the inner gear 33, and each planetary gear. 34, a second-stage sun gear 36 meshing with the planetary carrier 35, and a plurality of planetary gears 37 meshing with both the sun gear 36 and the inner gear 33.

A disc-shaped cover 2 is detachably attached to the inner periphery of the open end 20a of the rotary housing 20 to close the open end 20a.

A gear chamber 4 that accommodates a transmission mechanism 30 is formed by the inner surface of the rotary housing 20 , the outer surface of the main body portion 11 of the fixed housing 10 , and the cover 2 . The gear chamber 4 is filled with lubricant (lubricating oil) for lubricating the transmission mechanism 30 .

The fixed flange 12 is formed with an annular fixed projection 13 extending toward the rotary housing 20 . An annular rotation-side protrusion 23 extending toward the fixed housing 10 is formed radially inside the fixed-side protrusion 13 on the base end side of the rotation flange 29 of the rotation housing 20 .

A floating seal 50 is provided between the stationary housing 10 and the rotating housing 20 to seal the gap between the stationary housing 10 and the rotating housing 20 . The floating seal 50 includes a first elastic ring 51 provided on the fixed housing 10 , a first seal ring 53 supported by the fixed housing 10 via the first elastic ring 51 , and a second elastic ring provided on the rotary housing 20 . 52 and a second seal ring 54 supported by the rotary housing 20 via the second elastic ring 52 .

The first elastic ring 51 is an O-ring mounted on the sealing surface 14 formed on the stationary flange 12 of the stationary housing 10 . The second elastic ring 52 is an O-ring attached to the inner peripheral surface 21 of the rotation-side protrusion 23 of the rotation housing 20 . The first seal ring 53 and the second seal ring 54 are arranged so as to be in sliding contact with each other.

When the rotary housing 20 rotates, the first seal ring 53 and the second seal ring 54 are brought into sliding contact with each other to seal the oil in the power transmission device 100 so that it does not leak to the outside. Foreign matter such as mud is prevented from entering the power transmission device 100. - 特許庁

A labyrinth seal 5 is formed between the fixed housing 10 and the rotary housing 20 outside the floating seal 50 to prevent foreign matter from entering from the outside. The labyrinth seal 5 is formed by a gap between the facing surfaces of the fixed housing 10 and the rotary housing 20 . This prevents the floating seal 50 from being damaged by foreign matter.

A mounting structure of the bearing unit 40 will be described in detail with reference to FIG. The retaining ring 49 is a C-shaped member obtained by cutting a part of an annular member, and is configured so that the diameter thereof can be reduced by deforming so that both ends are brought closer to each other.

The pair of bearings 41 (first bearing 41a and second bearing 41b) includes an inner ring 42, an outer ring 43, balls 44 as a plurality of rolling elements arranged between the inner ring 42 and the outer ring 43, and balls and a retainer 45 that holds 44 . The first bearing 41a and the second bearing 41b have the same configuration and are arranged symmetrically. The bearing 41 is a single-row angular ball bearing in which a straight line connecting the contact points between the balls 44 and the inner ring 42 and the contact points between the balls 44 and the outer ring 43 has a predetermined angle (contact angle) with respect to the radial direction. .

In this embodiment, the fit between the inner ring 42 of the bearing 41 and the fixed housing 10 is a "tight fit", and the fit between the outer ring 43 of the bearing 41 and the rotary housing 20 is a "clearance fit".

A pair of bearings 41a and 41b are attached to the outer periphery of the fixed housing 10. As shown in FIG. The pair of bearings 41 a and 41 b are sandwiched between a stepped portion 16 provided on the outer periphery of the stationary housing 10 and the nut 60 . The nut 60 is screwed onto the threaded portion 17 formed on the outer periphery of the stationary housing 10 . A stepped portion 26 for restricting axial movement of the outer ring 43 of the second bearing 41b and a first recessed portion 25 in which a snap ring 49 is fitted are formed on the inner periphery of the rotary housing 20 . The first recess 25 has a semicircular cross section and is formed along the inner circumference of the rotation housing 20 .

A substantially 45-degree chamfered portion 46a is formed at an outer peripheral corner portion of the outer ring 43 of the first bearing 41a on the side of the second bearing 41b. Similarly, a substantially 45-degree chamfered portion 46b is formed at an outer peripheral corner portion of the outer ring 43 of the second bearing 41b on the side of the first bearing 41a. When the outer ring 43 of the first bearing 41a and the outer ring 43 of the second bearing 41b contact each other, the chamfered portion 45a and the chamfered portion 46a form a second concave portion 47 having a triangular cross section. A second recess 47 is formed along the outer circumference of the bearing 41 .

When the pair of bearings 41a and 41b are held between the nut 60 and the stepped portion 16, the second recess 47 and the first recess 25 are positioned to face each other. A retaining ring 49 is provided in an annular space surrounded by a first recess 25 formed on the inner periphery of the rotary housing 20 and a second recess 47 formed by contact between the outer rings 43 of the pair of bearings 41a and 41b. placed.

A bearing unit 40 composed of a pair of bearings 41 and a retaining ring 49 is mounted between the outer circumference of the fixed housing 10 and the inner circumference of the rotary housing 20 in the following manner.

As shown in FIG. 3, first, the first bearing 41a is attached to the fixed housing 10. As shown in FIG. The first bearing 41 a is fitted to the outer circumference of the fixed housing 10 until the inner ring 42 of the first bearing 41 a contacts the stepped portion 16 .

Next, the second bearing 41b is attached to the rotary housing 20. As shown in FIG. The second bearing 41b is fitted into the inner circumference of the rotary housing 20 until the outer ring 43 of the second bearing 41b comes into contact with the stepped portion 26 . After that, a C-shaped retaining ring 49 is fitted into the annular first recess 25 to prevent the second bearing 41 b from falling off from the rotation housing 20 . Note that the snap ring 49 can be easily inserted into the inner circumference of the rotary housing 20 because it has a structure that can be reduced in diameter. When positioned in the first recess 25 , the retaining ring 49 is expanded in diameter due to its elasticity and fitted into the first recess 25 .

Further, since the outer ring 43 of the second bearing 41b is formed with the chamfered portion 46b, when the retaining ring 49 is fitted into the first recess 25, the retaining ring 49 moves toward the first recessed portion 25 along the chamfered portion 46b. be guided. Therefore, the snap ring 49 can be easily fitted into the first recess 25 .

Next, the rotary housing 20 is brought close to the fixed housing 10, and the outer ring 43 of the second bearing 41b is brought into contact with the outer ring 43 of the first bearing 41a. Thereafter, as shown in FIG. 2, the bearing unit 40 is completed by fastening the nut 60 to the threaded portion 17 of the fixed housing 10 so that the nut 60 contacts the inner ring 42 of the second bearing 41b.

As described above, since the snap ring 49 is arranged in the space surrounded by the second recess 47 and the first recess 25, axial movement of the rotary housing 20 with respect to the bearing 41 fastened to the fixed housing 10 is restricted. be done. That is, the snap ring 49 prevents the rotary housing 20 from falling off from the fixed housing 10 .

Here, when a plurality of balls are arranged in the space surrounded by the first concave portion 25 and the second concave portion 47 in place of the snap ring 49, a slot for inserting the balls from the outside of the rotary housing 20 is formed. In addition, since it is necessary to insert the spheres one by one from the insertion holes and to properly manage the number of spheres, there is a problem that the manufacturing is troublesome.

On the other hand, in the present embodiment, a first recess 25 formed in the inner periphery of the rotary housing 20, a second recess 47 formed by contact between the outer rings 43 of the pair of bearings 41a and 41b, Since the retaining ring 49 is arranged in the space surrounded by , it is possible to prevent the rotation housing 20 from falling off from the fixed housing 10 without increasing the manufacturing cost.

Further, in this embodiment, the outer rings 43 of the pair of bearings 41a and 41b are in contact with each other. Therefore, the cumulative tolerance can be reduced compared to the case where the pair of bearings 41a and 41b are not brought into contact with each other and a separate member is interposed between the outer rings 43 of the pair of bearings 41a and 41b. As a result, the axial width tolerance of the first recess 25 in which the retaining ring 49 is arranged can be set small, so that the axial play in the bearing 41 can be suppressed.

As described above, the second seal ring 54 of the floating seal 50 is supported by the inner peripheral surface 21 of the rotary housing 20 via the second elastic ring 52 . Here, when the rotary housing 20 is axially misaligned with respect to the stationary housing 10, the pressing force of the second elastic ring 52 against the second seal ring 54 changes. Therefore, if the tolerance of the width of the first recess 25 in the axial direction is too large, the first seal ring 53 and the second seal ring 54 may be displaced from the fixed housing 10 when the rotary housing 20 is axially displaced. Oil may leak out from between

In contrast, in the present embodiment, the cumulative tolerance of the bearing unit 40 can be reduced, and the axial width tolerance of the first recess 25 in which the retaining ring 49 is arranged can be set small. Positional deviation between the housing 10 and the rotary housing 20 can be suppressed. As a result, deterioration of the sealing performance between the first seal ring 53 and the second seal ring 54 of the floating seal 50 can be suppressed.

According to the embodiment described above, the following effects are obtained.

In the power transmission device 100 according to the present embodiment, the first recess 25 formed in the inner circumference of the rotary housing 20 and the second recess 47 formed by contact between the outer rings 43 of the pair of bearings 41a Since the retaining ring 49 is arranged in the enclosed space, it is possible to prevent the rotary housing 20 from falling off from the stationary housing 10 without increasing the manufacturing cost. In addition, since the outer rings 43 of the pair of bearings 41a and 41b are in contact with each other, the accumulated tolerance can be reduced compared to the case where a separate member is interposed between the outer rings 43 of the pair of bearings 41a and 41b, thereby suppressing backlash. can do. In other words, according to the present embodiment, play of the bearing 41 can be suppressed without increasing the manufacturing cost.

Furthermore, since positional deviation between the fixed housing 10 and the rotary housing 20 is suppressed, deterioration of the sealing performance between the first seal ring 53 and the second seal ring 54 of the floating seal 50 is suppressed. be able to.

The following modifications are also within the scope of the present invention, and it is also possible to combine the configurations shown in the modifications with the configurations described in the above embodiments, or to combine the configurations described in the following different modifications. is.

<Modification 1>
In the above-described embodiment, an example in which the cross-sectional shape of the first concave portion 25 is a semicircular arc has been described, but the present invention is not limited to this. The cross-sectional shape of the 1st recessed part 25 can be made into various shapes. For example, the cross-sectional shape of the first recess 25 may be rectangular or triangular.

<Modification 2>
In the above embodiment, an example in which the cross-sectional shape of the second recess 47 is triangular has been described, but the present invention is not limited to this. The cross-sectional shape of the second concave portion 47 can be various shapes. For example, the cross-sectional shape of the second recess 47 may be semi-arcuate or rectangular.

<Modification 3>
In the above-described embodiment, an example in which the snap ring 49 is formed in a C-shape with a cut has been described, but the present invention is not limited to this. The retaining ring 49 may be a continuous annular member.

<Modification 4>
In the above embodiment, the nut 60 is screwed onto the threaded portion 17, and the pair of bearings 41a and 41b are sandwiched between the stepped portion 16 of the fixed housing 10 and the nut 60, but the present invention is not limited to this. Instead of screwing the nut 60 onto the threaded portion 17, an annular groove is provided along the outer periphery of the fixed housing 10, and a shim is fitted in this groove, so that the stepped portion 16 of the fixed housing 10 and the shim form a pair of bearings. 41a and 41b may be sandwiched.

The configuration, action, and effects of the embodiment of the present invention configured as described above will be collectively described.

The power transmission device 100 includes a fixed housing 10 that houses a drive source (hydraulic motor 9, electric motor), a rotating housing 20 that rotates by transmitting the output rotation of the drive source (hydraulic motor 9, electric motor), and a fixed housing. 10, a pair of bearings 41 that rotatably support the rotary housing 20 with respect to the fixed housing 10; , the outer rings 43 of the pair of bearings 41 are in contact with each other, the first recess 25 formed in the inner circumference of the rotary housing 20, and the second recess formed by the contact of the outer rings 43 of the pair of bearings 41. A retaining ring 49 is arranged in a space surrounded by the recess 47 .

In this configuration, a retaining ring 49 is provided in a space surrounded by a first recess 25 formed on the inner periphery of the rotary housing 20 and a second recess 47 formed by contact between the outer rings 43 of the pair of bearings 41 . is arranged, it is possible to prevent the rotation housing 20 from coming off from the fixed housing 10 without increasing the manufacturing cost. In addition, since the outer rings 43 of the pair of bearings 41 abut each other, the cumulative tolerance can be reduced and backlash can be suppressed compared to the case where a separate member is interposed between the outer rings 43 of the pair of bearings 41. . In other words, with this configuration, the backlash of the bearing 41 can be suppressed without increasing the manufacturing cost.

The power transmission device 100 is housed in a rotary housing 20, and includes a transmission mechanism 30 that changes the speed of the output rotation of a drive source (hydraulic motor 9, electric motor) and transmits it to the rotary housing 20; and a floating seal 50 for sealing a gap between the floating seal 50 and the first elastic ring 51 provided on the fixed housing 10 and the first elastic ring 51 supported by the fixed housing 10 via the first elastic ring 51 . It has a seal ring 53, a second elastic ring 52 provided on the rotary housing 20, and a second seal ring 54 supported by the rotary housing 20 via the second elastic ring 52 and in sliding contact with the first seal ring 53. .

In this configuration, the positional deviation between the fixed housing 10 and the rotary housing 20 is suppressed, thereby suppressing deterioration of the sealing performance between the first seal ring 53 and the second seal ring 54 of the floating seal 50. be able to.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have.

DESCRIPTION OF SYMBOLS 1... Drive device 9... Hydraulic motor (driving source) 10... Fixed housing 20... Rotating housing 25... First concave portion 30... Transmission mechanism 40... Bearing unit 41 Bearing 43 Outer ring 47 Second concave portion 49 Retaining ring 50 Floating seal 51 First elastic ring 52 - Second elastic ring, 53... First seal ring, 54... Second seal ring, 100... Power transmission device

Claims (2)

A power transmission device,
a stationary housing containing a drive source;
a rotating housing rotated by transmission of output rotation of the driving source;
a pair of bearings attached to the fixed housing for rotatably supporting the rotary housing with respect to the fixed housing;
a retaining ring having a circular cross-section for restricting relative movement of the bearing and the rotating housing in the axial direction;
The pair of bearings have the same configuration, and the outer rings are in contact with each other, and chamfered portions are formed at the outer peripheral corners of the respective outer rings on the side of the other bearing,
The snap ring is positioned in a space surrounded by a first recess formed on the inner periphery of the rotary housing and a second recess formed by the chamfered portions of the pair of bearings in contact with each other. A power transmission device characterized by being arranged in A power transmission device according to claim 1,
a speed change mechanism housed in the rotary housing, which changes the speed of output rotation of the drive source and transmits the speed to the rotary housing;
a floating seal that seals a gap between the stationary housing and the rotating housing;
The floating seal is
a first elastic ring provided on the fixed housing;
a first seal ring supported by the fixed housing via the first elastic ring;
a second elastic ring provided on the rotating housing;
a second seal ring that is supported by the rotary housing via the second elastic ring and is in sliding contact with the first seal ring.

Images