JP2023101431A - Driving force transmission device - Google Patents

Abstract

To provide a driving force transmission device for preventing the generation of a negative pressure in a cavity of a shaft seal part.SOLUTION: A driving force transmission device 10 includes a drive part for generating driving force, an output part for outputting the driving force of the drive part, a housing for storing the drive part and the output part, a rotary body connected to the drive part for transmitting driving force to the output part, a through-hole 32 provided in the housing and inserted through the rotary body, and a shaft seal part 41 provided in the through-hole 32 for sliding with the rotary body, the shaft seal part 41 having a drive part side seal member 42 located on the drive part side, an output part side seal member 43 located on the output part side, and an annular member 44 for defining a cavity 61 between the drive part side seal member 42 and the output part side seal member 43 in the axial direction of the rotary body together with the rotary body, the housing including a communication path 64 for communicating the through-hole 32 with the outside, the annular member 44 having a cutout 63 for communicating the communication path 64 with the cavity 61.SELECTED DRAWING: Figure 4

Description

The present invention relates to a driving force transmission device.

2. Description of the Related Art As a conventional technology related to a driving force transmission device, for example, an oil seal for a rotating shaft disclosed in Patent Document 1 is known. The rotary shaft oil seal disclosed in Patent Document 1 is applied to a self-priming general-purpose pump, and is arranged between an oil chamber of lube oil that lubricates the mechanical seal of the rotary shaft and an oil chamber of bearing oil that lubricates the bearing, via a bearing housing. The oil seal is a double oil seal that combines a pair of oil seals. The pair of oil seals are arranged via shims so that the dust lips of the pair of oil seals face each other inward.

By forming a double oil seal that combines a set of oil seals, even if the oil seal suction phenomenon occurs, the movement of oil due to this can be offset, and the movement (oil leakage) between the lube oil and the bearing oil can be prevented.

JP-A-8-296743

However, in the oil seal for the rotating shaft disclosed in Patent Document 1, there is a problem that the space in the shaft seal portion (the space defined by the shim and the pair of oil seals) becomes negative pressure as the rotating body (rotating shaft) rotates. When the space in the shaft seal portion becomes negative pressure, the sliding resistance between the rotating body and the shaft seal portion increases, and the seal member of the shaft seal portion is deformed, resulting in reduced durability and possibly failing to function as a seal member.

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving force transmission device that prevents generation of negative pressure in a gap in a shaft seal portion.

In order to solve the above-described problems, the present invention provides a driving force transmission device comprising: a driving portion that generates a driving force; an output portion that outputs the driving force of the driving portion; a housing that accommodates the driving portion and the output portion; a rotating body that is connected to the driving portion and transmits the driving force to the output portion; a through hole provided in the housing through which the rotating body is inserted; an output part-side seal member located on the output part side; and an annular member defining a gap together with the rotor between the drive part-side seal member and the output part-side seal member in the axial direction of the rotor.

In the present invention, the drive section side seal member and the output section side seal member seal the through hole between the drive section and the output section. The notch of the annular member communicates with the communication passage provided in the housing, so that the gap formed together with the rotating body between the drive side seal member and the output side seal member in the axial direction of the rotor communicates with the outside. Therefore, even if the rotating body rotates, the air gap will not become negative pressure. Therefore, negative pressure in the gap in the shaft seal can be prevented.

Further, in the driving force transmission device described above, radial movement of the annular member with respect to the housing may be restricted.
In this case, since the annular member is not moved in the radial direction with respect to the housing, the notch of the annular member can reliably communicate with the communication passage provided in the housing.

Further, in the driving force transmission device described above, the axial length of the notch may correspond to the plate thickness of the annular member, and the annular member may be pressed against the inner peripheral surface of the housing by the elastic force of the annular member.
In this case, the annular member is pressed against the inner peripheral surface of the housing by the restoring force of elastic deformation. Therefore, it is possible to prevent radial movement of the annular member with respect to the housing.

Further, in the driving force transmission device described above, the driving portion may include an electric motor for driving an industrial vehicle and a reduction mechanism for reducing the rotational force of the electric motor, and the output portion may include a pair of left and right axles rotatably supported by the housing, and a differential mechanism for distributing the driving force to the pair of left and right axles.
In this case, even if lubricating oils having different viscosities are filled in the drive section and the output section of the industrial vehicle, the lubricating oils will not be mixed due to the shaft seal member. In addition, it is possible to prevent negative pressure from being generated in the shaft seal member of the driving force transmission device for industrial vehicles, which tends to have limited space.

Advantageous Effects of Invention According to the present invention, it is possible to provide a driving force transmission device that prevents generation of negative pressure in a gap in a shaft seal portion.

1 is a schematic plan view of a driving force transmission device according to an embodiment of the present invention; FIG. 1 is a cross-sectional view of a driving force transmission device according to an embodiment of the present invention; FIG. 3 is a cross-sectional view of a shaft seal portion in the driving force transmission device according to the embodiment of the invention; FIG. FIG. 4 is a vertical cross-sectional view of a shaft seal portion in the driving force transmission device according to the embodiment of the present invention; FIG. 4 is a perspective view of an annular member; FIG. 4 is an explanatory diagram for explaining a gap in the shaft seal portion; It is a perspective view of the annular member which concerns on a modification.

A driving force transmission device according to an embodiment of the present invention will be described below with reference to the drawings. The driving force transmission device of this embodiment is a driving force transmission device mounted on an electric forklift as an industrial vehicle. The forward/backward, left/right, and up/down directions are based on the state where the operator of the electric forklift is seated in the driver's seat.

A driving force transmission device 10 shown in FIG. 1 is mounted on a vehicle body (not shown) of an electric forklift. The driving force transmission device 10 includes a driving portion 11 that generates driving force for running, an output portion 12 that transmits the driving force of the driving portion 11 to driving wheels (not shown), and a housing 13 that accommodates the driving portion 11 and the output portion 12. The front portion of the drive force transmission device 10 is the output portion, and the rear portion of the drive force transmission device 10 is the drive portion 11 .

The drive unit 11 includes a pair of left and right electric motors 14 for running, and a speed reduction mechanism 15 that reduces and concentrates the torque of the pair of left and right electric motors 14 . A part of the electric motor 14 is omitted from the drawing. The output unit 12 includes a differential mechanism 16 connected to the reduction mechanism 15 and a pair of left and right axles 17 . As shown in FIGS. 1 and 2, the housing 13 has a first housing body 18, a second housing body 19, a third housing body 20 and a fourth housing body 21. As shown in FIGS.

A first housing body 18 is attached to the front end of the electric motor 14 . The second housing body 19 is joined to the front end of the first housing body 18 . The third housing body 20 is joined to the front end of the second housing body 19 . The fourth housing body 21 is joined to the third housing body 20 . The first housing body 18 , the second housing body 19 and the third housing body 20 form a drive-side space E<b>1 that accommodates the speed reduction mechanism 15 . The third housing body 20 and the fourth housing body 21 form an output side space E2 in which the differential mechanism 16 and the pair of left and right axles 17 are accommodated. Incidentally, the drive-side space E1 is filled with a low-viscosity lubricating oil that suppresses a decrease in power loss, and the output-side space E2 is filled with a lubricating oil having a higher viscosity than the lubricating oil that is filled in the drive-side space E1 in order to ensure durability. Incidentally, the high-viscosity lubricating oil filled in the output-side space E2 is lubricating oil equivalent or substantially equivalent to lubricating oil used in engine type forklifts.

As shown in FIG. 2, the electric motor 14 has a motor body 22 and a motor shaft 23 that rotates. A motor gear 24 that rotates integrally with the motor shaft 23 is provided on the motor shaft 23 coaxially with the motor shaft 23 . Axial centers of the motor shaft 23 and the motor gear 24 extend in the front-rear direction. A bearing 25 that supports the motor gear 24 is provided in the first housing body 18 , and a bearing 26 that supports the motor gear 24 is provided in the third housing body 20 .

The reduction mechanism 15 includes a first reduction gear 27 that meshes with the motor gear 24 . A pair of first reduction gears 27 are arranged on the left and right in correspondence with the pair of left and right motor gears 24 . A bearing 28 that supports the first reduction gear 27 is provided in the first housing body 18 , and a bearing 29 that supports the first reduction gear 27 is provided in the third housing body 20 . The axial direction of the pair of left and right first reduction gears 27 is substantially parallel to the axial direction of the motor gear 24 .

The reduction mechanism 15 includes a second reduction gear 30 that meshes with a pair of left and right first reduction gears 27 . The second reduction gear 30 is integrated with a pinion gear 31 inserted from the drive-side space E1 to the output-side space E2 by spline fitting. A through hole 32 through which a pinion gear 31 is inserted is formed in the third housing body 20 . The axial directions of the second reduction gear 30 and the pinion gear 31 are substantially parallel to the axial direction of the first reduction gear 27 .

The pinion gear 31 has a shaft portion 33 inserted through the through hole 32 and spline-fitted with the second reduction gear 30 , and a gear portion 34 provided at the output side end portion of the shaft portion 33 . An end portion of the shaft portion 33 on the drive side space E1 side is supported by the first housing body 18 via a bearing 35 . An end portion of the shaft portion 33 on the output side space E2 side is supported by the third housing body 20 via a bearing 36 . The gear portion 34 is a helical gear.

The differential mechanism 16 has differential gears 37 provided on the pair of left and right axles 17, respectively, and a differential gear (not shown) that is rotatably supported by the fourth housing body 21 and meshes with the pair of left and right differential gears 37. The axle 17 is supported by the third housing body 20 via bearings 39 . A driving wheel is attached to the end of the axle 17 via a hub (not shown). The right axle 17 is provided with a ring gear 40 coaxially with the axle 17 . The ring gear 40 meshes with the gear portion 34 of the pinion gear 31 . Therefore, the rotational force of the pinion gear 31 is transmitted to the right axle 17 via the gear portion 34 and the ring gear 40, and to the left axle 17 via the differential gear 37 and a differential gear (not shown).

By the way, the driving force transmission device 10 has a shaft seal portion 41 that seals a gap between the through hole 32 and the second reduction gear 30 spline-fitted to the pinion gear 31 . As shown in FIG. 3, the second reduction gear 30 has a boss portion 30A having a spline hole 30B and a gear portion 30C radially extending from the boss portion 30A. The shaft seal portion 41 has a drive side seal member 42 facing the drive side space E1, an output side seal member 43 facing the output side space E2, and an annular member 44 interposed between the drive side seal member 42 and the output side seal member 43. A chamfered portion 30D is provided between the end surface of the boss portion 30A on which the drive portion side seal member 42 and the output portion side seal member 43 are mounted and the outer peripheral surface.

As shown in FIG. 4, the drive-side seal member 42 is a pressure-resistant oil seal that can withstand the pressure of the lubricating oil in the drive-side space E1. The driving portion side seal member 42 has a seal body 45 , a reinforcing ring 46 , a lip portion 47 and a garter spring 48 . A seal body 45 that partitions the space of the through hole 32 in the third housing body 20 is made of an oil-resistant rubber material. The cross section of the seal body 45 is substantially L-shaped, and the seal body 45 is integrally formed with a reinforcing ring 46 having a substantially L-shaped cross section. The reinforcing ring 46 is made of a metal material and functions as a reinforcing member that maintains the annular shape of the seal body 45 .

As shown in FIG. 4 , a lip portion 47 is provided on the inner peripheral side of the seal body 45 . The lip portion 47 is in sliding contact with the outer peripheral surface of the boss portion 30</b>A of the second reduction gear 30 and protrudes in a mountain shape from the inner peripheral side of the seal body 45 toward the center of the seal body 45 . The lip portion 47 faces the drive-side space E1 and is in pressure contact with the outer peripheral surface of the boss portion 30A to prevent leakage of lubricating oil filled in the drive-side space E1.

As shown in FIG. 4, a garter spring 48 is attached to the outer peripheral side of the lip portion 47 . The garter spring 48 has a function of increasing the fastening force of the lip portion 47 by pressing the lip portion 47 radially inward and enhancing the sealing performance of the driving portion side seal member 42 . The garter spring 48 is a steel coil spring and has an annular shape.

As shown in FIG. 4, the output side seal member 43 is located closer to the output side space E2 than the drive side seal member 42, and is a pressure-resistant oil seal that can withstand the pressure of the lubricating oil in the output side space E2. The output section side seal member 43 has a seal body 55 , a reinforcing ring 56 , a lip section 57 and a garter spring 58 . A seal body 55 that partitions the space of the through hole 32 in the third housing body 20 is made of an oil-resistant rubber material. The cross section of the seal body 55 is substantially L-shaped, and the seal body 55 is integrally formed with a reinforcing ring 56 having a substantially L-shaped cross section. The reinforcing ring 56 is made of a metal material and functions as a reinforcing member that maintains the annular shape of the seal body 55 .

As shown in FIG. 4 , a lip portion 57 is provided on the inner peripheral side of the seal body 55 . The lip portion 57 is in sliding contact with the outer peripheral surface of the boss portion 30</b>A of the second reduction gear 30 and protrudes in a mountain shape from the inner peripheral side of the seal body 55 toward the center of the seal body 55 . The lip portion 57 is positioned facing the output side space E2, is in pressure contact with the outer peripheral surface of the boss portion 30A, and prevents leakage of lubricating oil filled in the output side space E2.

As shown in FIG. 4, a garter spring 58 is attached to the outer peripheral side of the lip portion 57 . The garter spring 58 has a function of increasing the fastening force of the lip portion 57 by pressing the lip portion 57 radially inward and improving the sealing performance of the drive portion side seal 51 . The garter spring 58 is a steel coil spring and has an annular shape.

As shown in FIG. 4, an annular member 44 is interposed between the output side seal member 43 and the drive side seal member 42 in the axial direction. As shown in FIG. 5, the annular member 44 is a member formed by punching a metal plate, and has an insertion hole 61 through which the shaft portion 33 of the pinion gear 31 and the boss portion 30A of the second reduction gear 30 are inserted, an outer peripheral surface 62 that contacts the inner wall of the through hole 32, and a notch 63 that traverses the radial direction. The inner diameter of the insertion hole 61 is larger than the outer peripheral diameter of the outer peripheral surface of the boss portion 30A so that there is a gap between the annular member 44 and the boss portion 30A. The diameter of the outer peripheral surface 62 of the annular member 44 is formed larger than the diameter of the through hole 32 . The inner diameter (hole diameter) of the annular member 44 and the diameter of the through hole 32 of the annular member 44 can be freely set within a range that does not contact the outer peripheral surface of the boss portion 30A. The annular member 44 is not a complete ring that is continuous in the circumferential direction, but is cut in the middle by the notch 63 .

As shown in FIG. 4, the third housing body 20 is formed with a communication passage 64 that communicates the through hole 32 with the outside. The annular member 44 is mounted in the through hole 32 so that the notch 63 communicates with the communicating passage 64, and the output side seal member 43 and the drive side seal member 42 are arranged to sandwich the annular member 44 in the axial direction. The outer peripheral surface of the boss portion 30A, the output portion side seal member 43, the drive portion side seal member 42 and the annular member 44 form an annular gap 65. As shown in FIG. The gap 65 communicates with the communicating path 64 via the notch 63 . Since the diameter of the outer peripheral surface 62 of the annular member 44 is larger than the inner peripheral diameter of the through hole 32 before being elastically deformed, the restoring force (elastic force) of the elastic deformation of the annular member 44 presses the annular member 44 against the third housing body 20, thereby restricting the rotation of the annular member 44 in the circumferential direction.

Next, the operation of the driving force transmission device 10 according to this embodiment will be described. When the electric forklift runs, the pair of left and right electric motors 14 are driven. When the motor shaft 23 of the electric motor 14 rotates, the motor gear 24 rotates integrally with the motor shaft 23 . Rotation of the motor gear 24 is transmitted to the first reduction gear 27 , and rotation of the first reduction gear 27 is transmitted to the second reduction gear 30 meshing with the first reduction gear 27 . The rotation transmitted from the motor gear 24 to the second reduction gear 30 is reduced according to the reduction ratio. As the second reduction gear 30 rotates, the pinion gear 31 spline-fitted with the second reduction gear 30 rotates.

As the pinion gear 31 rotates, the ring gear 40 meshing with the pinion gear 31 rotates, and the right axle 17 rotates integrally with the ring gear 40 . Rotation of the right axle 17 is transmitted to the left axle 17 via a differential gear 37 and a differential gear (not shown) meshing with the differential gear 37 . By rotating the left and right axles 17, the drive wheels rotate and the electric forklift runs.

The low-viscosity lubricating oil filled in the drive-side space E1 lubricates sliding portions such as the motor gear 24, the first reduction gear 27, the second reduction gear 30, and the like. The high-viscosity lubricating oil filled in the output-side space E2 lubricates sliding portions such as the gear portion 34 of the pinion gear 31, the ring gear 40, the differential gears 37 and 38, and the like. The through-hole 32 in the third housing body 20 communicates the drive-side space E1 and the output-side space E2, but the shaft seal portion 41 provided between the boss portion 30A of the second reduction gear 30 inserted through the through-hole 32 and the through-hole 32 seals the drive-side space E1 and the output-side space E2.

The drive-side seal member 42 of the shaft seal portion 41 prevents low-viscosity lubricating oil from flowing out from the drive-side space E1 to the output-side space E2. The output side seal member 43 of the shaft seal portion 41 prevents low-viscosity lubricating oil from flowing out from the output side space E2 to the drive side space E1. By interposing the annular member 44 between the drive section side seal member 42 and the output section side seal member 43, an annular gap 65 is formed by the outer peripheral surface of the boss section 30A, the output section side seal member 43, the drive section side seal member 42 and the annular member 44. The output section side seal member 43 and the drive section side seal member 42 are in sliding contact with the boss portion 30A of the second reduction gear 30 . Since the gap 65 communicates with the communicating path 64 through the notch 63, the gap 65 maintains the atmospheric pressure. That is, the pressure in the gap 65 never drops below atmospheric pressure.

The driving force transmission device 10 of this embodiment has the following effects.
(1) The drive section side seal member 42 and the output section side seal member 43 seal the through hole 32 between the drive section 11 and the output section 12 . A notch 63 of the annular member 44 communicates with a communication passage 64 provided in the housing 13, so that a gap 65 formed together with the boss portion 30A between the drive portion side seal member 42 and the output portion side seal member 43 in the axial direction of the boss portion 30A of the second reduction gear 30 communicates with the outside. Therefore, even if the second reduction gear 30 rotates, the air gap 65 will not become negative pressure. Therefore, negative pressure in the gap 65 in the shaft seal portion 41 can be prevented.

(2) Since the annular member 44 does not move radially with respect to the housing 13 , the notch 63 of the annular member 44 can reliably communicate with the communication passage 64 provided in the housing 13 . Specifically, the annular member 44 having the notch 63 has an outer peripheral surface 62 with a larger diameter than the inner peripheral surface of the housing 13 before being elastically deformed. Therefore, the annular member 44 is pressed against the inner peripheral surface of the housing 13 by the restoring force of elastic deformation. As a result, radial movement of the annular member 44 with respect to the housing 13 can be prevented.

(3) The drive unit 11 includes an electric motor 14 for running, and a speed reduction mechanism 15 that reduces the rotational force of the electric motor 14 . The output unit 12 includes a pair of left and right axles 17 rotatably supported by the housing 13 and a differential mechanism 16 that distributes driving force to the pair of left and right axles 17 . Therefore, even if the driving portion 11 and the output portion 12 in the housing 13 are filled with lubricating oils having different viscosities, the shaft seal portion 41 prevents the lubricating oils from being mixed.

(4) The annular member 44 has a simple structure that can be formed by stamping a metal plate, and can reduce manufacturing costs. In addition, since the annular member 44 is plate-shaped, it is possible to reliably form the gap 65 at a location subject to space restrictions. Furthermore, by using the annular member 44, the distance in the axial direction between the drive section side seal member 42 and the output section side seal member 43 in the shaft seal portion 41 can be reduced. It is possible to prevent negative pressure from being generated in the shaft seal portion 41 of the driving force transmission device 10 for an electric forklift, which tends to have limited space.

(5) Since the axial distance between the drive side seal member 42 and the output side seal member 43 in the shaft seal portion 41 can be reduced, the chamfered surface of the chamfered portion 30D of the boss portion 30A of the second reduction gear 30 can be increased. By enlarging the chamfered surface of the chamfered portion 30</b>D, the workability of assembling the drive portion side seal member 42 and the output portion side seal member 43 to the second reduction gear 30 is further improved.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention. For example, the following modifications may be made.

(circle) in said embodiment, although the notch of the annular member was formed so that the annular member might be crossed to radial direction, it is not restricted to this. For example, as shown in FIG. 7, the notch of the annular member may be a groove-shaped recess 74 extending from the outer peripheral surface 73 to the insertion hole 72 on one of the plate surfaces of the annular member 71 . In FIG. 7, since a plurality of recesses 74 as cutouts are arranged in the circumferential direction, the diameter of the outer peripheral surface 73 of the annular member 71 should be made smaller than the inner peripheral diameter of the through hole 32 of the housing 13 so that the annular member 71 can rotate with respect to the housing 13. By rotating the annular member 71 due to the rotation of the rotating body, one of the recesses 74 communicates with the communicating passage 64, and the gap 65 does not become negative pressure.
○ In the above embodiment, the annular member was not fixed to the drive section side seal member and the output section side seal member, but the ring member may be fixed to at least one of the drive section side seal member and the output section side seal member by fixing means such as adhesive tape or adhesive. In this case, it is not necessary to make the diameter of the outer peripheral surface of the annular member larger than the inner peripheral diameter of the through hole, and it is easy to align the notch with the communicating passage.
O In the above embodiment, the driving force transmission device for an electric forklift as an industrial vehicle was illustrated, but the present invention is not limited to this. The present invention is not limited to industrial vehicles, and may be any driving force transmission device that outputs driving force from a driving source to an output unit.

10 Driving force transmission device 11 Drive unit 12 Output unit 13 Housing 14 Electric motor 15 Reduction mechanism 16 Differential mechanism 17 Axle 24 Motor gear 27 First reduction gear 30 Second reduction gear 31 Pinion gear 32 Through hole 41 Shaft seal 42 Drive unit side seal member 43 Output side seal members 44, 71 Annular members 61, 72 Insertion holes 62, 73 Outer peripheral surface 63 Cut Notch 64 Communication path 65 Gap 74 Concave portion (notch)
E1 Drive side space E2 Output side space

Claims (4)

a driving unit that generates a driving force;
an output unit that outputs the driving force of the driving unit;
a housing that accommodates the drive section and the output section;
a rotating body connected to the drive unit and transmitting a driving force to the output unit;
a through hole provided in the housing through which the rotating body is inserted;
A driving force transmission device having a shaft seal provided in the through hole and sliding on the rotating body,
The shaft seal portion is
a driving portion side seal member located on the driving portion side;
an output section side sealing member positioned on the output section side;
an annular member defining a gap together with the rotating body between the drive side seal member and the output side seal member in the axial direction of the rotating body;
The housing has a communication passage that communicates the communication hole with the outside,
The driving force transmission device, wherein the annular member has a notch that communicates the communication passage and the space. 2. A driving force transmission device according to claim 1, wherein radial movement of said annular member with respect to said housing is restricted. The axial length of the notch corresponds to the plate thickness of the annular member,
3. The driving force transmission device according to claim 1, wherein said annular member is pressed against the inner peripheral surface of said housing by an elastic force of said annular member. The drive unit
an electric motor for running an industrial vehicle;
a reduction mechanism that reduces the rotational force of the electric motor,
The output unit
a pair of left and right axles rotatably supported by the housing;
3. The driving force transmission device according to claim 1, further comprising a differential mechanism for distributing the driving force to the pair of left and right axles.

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