Power transmission device

Abstract

To provide a driving force transmission device for preventing the occurrence of a negative pressure in a gap of a shaft seal part.SOLUTION: The driving force transmission device includes a driving part, an output part, a housing storing the driving part and the output part, a rotary body connected to the driving part for transmitting driving force to the output part, a through-hole 31 provided in the housing and inserted through the rotary body, and a shaft seal part 41 provided in the through-hole 31 for sliding with the rotary body, the shaft seal part 41 having a driving part side seal member, and an output part side seal member located on the output part side so that a gap from the driving part side seal member is provided in the axial direction of the rotary body, the housing including a communication path 60 for communicating the through-hole 31 with the outside. The communication path 60 includes a through-hole side opening 61 formed in the hole wall surface of the through-hole 31, existing between the driving part side seal member 42 and the output part side seal member 43, and opposed to the gap, and an outside opening 62 located below the through-hole opening 61 and formed in the outside face of the housing.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This invention relates to a driving force transmission device.

Background Art

[0002] As a conventional technique related to a driving force transmission device, for example, an oil seal disclosed in Patent Document 1 is known. The oil seal disclosed in Patent Document 1 is an oil seal provided at an outer peripheral position of a crankshaft and sealing two liquids of lubricating oil and engine oil.

[0003] The oil seal of Patent Document 1 includes a first seal that seals the flywheel side, a second seal that seals the engine side, and a partition lip disposed between the first seal and the second seal. A space surrounded by the first seal, the second seal, and the crankshaft is formed in the oil seal, and the partition lip divides this space. A pressure relief hole that communicates with the divided space on the flywheel side of the divided space is provided in the first seal. Further, a communication hole that communicates the two divided spaces is provided in the partition lip. According to this type of oil seal, it is said that deterioration of the sealing performance due to wear is suppressed, and liquid in one isolation space is prevented from being discharged into the other isolation space.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the oil seal described in Patent Document 1, although air from the flywheel side mixes with lubricating oil and communicates with the divided space on the flywheel side through the pressure relief hole, if there is no air around the shaft seal portion (oil seal) and it is filled with lubricating oil, there is a risk that the negative pressure in the space (divided space) in the shaft seal portion cannot be completely relieved. If the negative pressure in the space in the shaft seal portion is not relieved, the shaft seal portion (first seal, second seal) is pressed against the rotating body (crankshaft), which leads to a problem of reduced durability of the shaft seal portion.

[0006] The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide a driving force transmission device that prevents the generation of negative pressure in the gap of the shaft seal portion. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a drive unit that generates a driving force, an output unit that outputs the driving force of the drive unit, and the drive unit Drive side space that accommodates and housing the output unit Forms the output side space The power transmission device comprises a housing, a rotating body connected to the drive unit and transmitting power to the output unit, a through hole provided in the housing through which the rotating body is inserted, and a shaft seal portion provided in the through hole and sliding with the rotating body, wherein the shaft seal portion comprises a drive unit side seal member located on the drive unit side and an output unit side seal member located on the output unit side such that a gap is provided between the drive unit side seal member and the rotating body in the axial direction, and the housing comprises a communication passage connecting the through hole and the outside, wherein the communication passage is formed on the hole wall surface of the through hole in the housing, is located between the drive unit side seal member and the output unit side seal member and faces the gap, and has an outer opening located below the through hole side opening and formed on the outer surface of the housing The structure comprises a first passage section having the through-hole side opening, and a second passage section communicating with the first passage section and having the outer opening, wherein the diameter of the hole in the second passage section is larger than the diameter of the hole in the first passage section. It is characterized by the following:

[0008] In this invention, the through-hole side opening of the communication passage is formed on the hole wall surface of the through-hole in the housing, located between the drive-side sealing member and the output-side sealing member, and facing the gap between the drive-side sealing member and the output-side sealing member. The outer opening is located below the through-hole side opening and is formed on the outer surface of the housing. Therefore, the gap between the drive-side sealing member and the output-side sealing member in the axial direction of the rotating body is in communication with the outside. Consequently, even when the rotating body rotates, the gap does not become negatively pressurized. Furthermore, because the outer opening of the communication passage is located below the through-hole side opening, foreign matter that enters the communication passage is more likely to fall downwards, and foreign matter is less likely to enter the gap in the shaft seal. Consequently, the function of the shaft seal and the durability required for the shaft seal can be maintained. Furthermore, since the diameter of the hole in the second passage is larger than the diameter of the hole in the first passage, foreign matter is more likely to fall downwards in the second passage and less likely to enter the first passage.

[0009] Furthermore, in the above-mentioned drive force transmission device, The drive unit side sealing member and the output unit side sealing member each have a seal body, a lip portion, and a reinforcing ring, respectively, the gap is a space separated from the drive side space and the output side space, and the reinforcing ring is provided on each seal body so as not to be exposed in the gap. The structure is also good. 。

[0010] Furthermore, in the above-described drive force transmission device, the communication passage may be configured to include a check valve that allows air to flow from the outside towards the gap. In this case, the presence of a check valve in the second passage makes it difficult for foreign objects to enter through the gap in the shaft seal.

[0011] Furthermore, in the above-described drive force transmission device, the drive unit may be configured to 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 unit may be configured to include a pair of left and right axles rotatably supported in the housing and a differential mechanism for distributing driving force to the pair of left and right axles. In this case, even if lubricating oils of different viscosities are filled in the drive and output sections of an industrial vehicle, the lubricating oils will not mix due to the shaft seal. Furthermore, it is possible to prevent the generation of negative pressure in the shaft seal section of the power transmission device of an industrial vehicle, where space is often constrained.

[0012] Furthermore, in the above-described drive force transmission device, a pair of bearings are arranged in the axial direction of the rotating body in the through hole, and the rotating body comprises a rotating body body rotatably supported by the pair of bearings, and a cylindrical collar member fixed to the rotating body body so as to be located between the pair of bearings in the through hole, and the shaft seal portion may be configured to slide against the collar member. In this case, the collar member is fixed to the rotating body so that it is positioned between the pair of bearings, and the shaft seal slides against the collar member, thereby suppressing a decrease in the sealing function due to play in the rotating body. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a driving force transmission device that prevents the generation of negative pressure in the gap of the shaft seal portion. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic plan view of a drive force transmission device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view of a drive force transmission device according to an embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the main part of a drive force transmission device according to an embodiment of the present invention. [Figure 4] This is a longitudinal cross-sectional view showing the main part of a drive force transmission device according to an embodiment of the present invention. [Figure 5] This is a longitudinal cross-sectional view showing a partially enlarged view of the main part of a drive force transmission device according to an embodiment of the present invention. [Figure 6] This is a longitudinal cross-sectional view showing the main part of a modified power transmission device. [Modes for carrying out the invention]

[0015] Hereinafter, a driving force transmission device according to an embodiment of the present invention will be described with reference to the drawings. The driving force transmission device of the present embodiment is a driving force transmission device mounted on an electric forklift as an industrial vehicle. Regarding the front and rear, left and right, and up and down indicating directions, it is based on the state where the operator of the electric forklift is seated in the driver's seat.

[0016] The driving force transmission device 10 shown in FIGS. 1 and 2 is mounted on the vehicle body (not shown) of the electric forklift. The driving force transmission device 10 includes a driving unit 11 that generates a driving force for traveling, an output unit 12 that transmits the driving force of the driving unit 11 to driving wheels (not shown), and a housing 13 that houses the driving unit 11 and the output unit 12. The front part of the driving force transmission device 10 is the output unit 12, and the rear part of the driving force transmission device 10 is the driving unit 11.

[0017] The driving unit 11 includes a pair of left and right electric motors 14 for traveling and a speed reduction mechanism 15 that decelerates and aggregates the rotational forces of the pair of left and right electric motors 14. A part of the electric motor 14 is not shown. The output unit 12 includes a differential mechanism 16 connected to the speed 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, and a third housing body 20.

[0018] The first housing body 18 is attached to the front end portion of the electric motor 14. The second housing body 19 is joined to the front end portion of the first housing body 18. The third housing body 20 is joined to the front end portion of the second housing body 19. The first housing body 18 and the second housing body 19 form a driving side space E1 that houses the speed reduction mechanism 15.

[0019] The second housing 19 and the third housing 20 form an output-side space E2 that houses the differential mechanism 16 and a pair of left and right axles 17. The drive-side space E1 is filled with a low-viscosity lubricant to suppress the reduction of power loss, while the output-side space E2 is filled with a higher-viscosity lubricant than the one in the drive-side space E1 to ensure the durability of the differential mechanism 16 and other components. The high-viscosity lubricant filled in the output-side space E2 is equivalent to or nearly equivalent to the lubricant used in engine-powered forklifts.

[0020] As shown in Figure 2, the electric motor 14 has a motor body 21 and a rotating motor shaft 22. A motor gear 23 that rotates integrally with the motor shaft 22 is mounted coaxially with the motor shaft 22. The axes P of the motor shaft 22 and the motor gear 23 extend in the front-rear direction. The first housing body 18 is provided with a bearing 24 that supports the motor gear 23, and the second housing body 19 is provided with a bearing 25 that supports the motor gear 23.

[0021] The reduction mechanism 15 includes a first reduction gear 26 that meshes with the motor gear 23. The first reduction gear 26 is arranged in pairs on the left and right sides, corresponding to the left and right motor gears 23. The first housing body 18 is provided with a bearing 27 that supports the first reduction gear 26, and the third housing body 20 is provided with a bearing 28 that supports the first reduction gear 26. The axial directions of the left and right pair of first reduction gears 26 are approximately parallel to the axial direction of the motor gear 23.

[0022] The reduction mechanism 15 includes a second reduction gear 29 that meshes with a pair of left and right first reduction gears 26. The second reduction gear 29 is a gear integrated with a pinion gear 30 inserted from the drive-side space E1 to the output-side space E2 by spline fitting. The second housing body 19 has a through hole 31 through which the pinion gear 30 is inserted. The axes Q of the second reduction gear 29 and the pinion gear 30 are approximately parallel to the axis P of the first reduction gear 26.

[0023] The pinion gear 30 corresponds to a rotating body and has a shaft portion 32 as the rotating body body that is inserted through a through hole 31 and into which the second reduction gear 29 is spline-fitted, and a gear portion 33 provided at the output end of the shaft portion 32. The end of the shaft portion 32 on the drive side space E1 side is supported by the first housing body 18 via a bearing 34. The end of the shaft portion 32 on the output side space E2 side is supported by the second housing body 19 via a bearing 35. The portion of the shaft portion 32 between the bearing 35 and the second reduction gear 29 is supported by the second housing body 19 via a bearing 36. The bearings 35 and 36 are tapered roller bearings. The gear portion 33 is a helical gear. A collar member 37 is provided between the second reduction gear 29 and the gear portion 33 of the pinion gear 30. The collar member 37 is a cylindrical member and is fitted onto the shaft portion 32 by press fitting. The collar member 37 is compressed in the direction of the axis Q by bearings 35 and 36.

[0024] The differential mechanism 16 includes differential gears 38 provided on each of the left and right axles 17, and a differential gear (not shown) rotatably supported by the second housing 19 and meshing with the left and right differential gears 38. The axles 17 are supported by the second housing 19 via bearings 39. Drive wheels are attached to the ends of the axles 17 via hubs (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 33 of the pinion gear 30. Therefore, the rotational force of the pinion gear 30 is transmitted to the right axle 17 via the gear portion 33 and the ring gear 40, and to the left axle 17 via the differential gear 38 and a differential gear (not shown). The axis R of the axle 17 is perpendicular to the axes P and Q.

[0025] Incidentally, the drive force transmission device 10 has a shaft seal portion 41 that seals the gap between the hole wall of the through hole 31 and the collar member 37. As shown in Figure 3, the shaft seal portion 41 separates the drive-side space E1 and the output-side space E2. The shaft seal portion 41 has a drive-side seal member 42 facing the drive-side space E1 and an output-side seal member 43 facing the output-side space E2.

[0026] As shown in Figures 4 and 5, the drive unit side seal member 42 is a pressure-resistant oil seal capable of withstanding the pressure of the lubricating oil in the drive side space E1. The drive unit side seal member 42 includes a seal body 45, a reinforcing ring 46, a lip portion 47, and a gutter spring 48. The seal body 45, which partitions the space of the through hole 31 in the second housing body 19, is made of an oil-resistant rubber material. The cross-section of the seal body 45 is approximately L-shaped, and the seal body 45 is integrally formed with the reinforcing ring 46, which also has an approximately 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.

[0027] As shown in Figure 5, a lip portion 47 is provided on the inner circumference of the seal body 45. The lip portion 47 slides against the outer surface of the collar member 37 and is formed to protrude in a mountain shape from the inner circumference of the seal body 45 toward the center of the seal body 45. The lip portion 47 is positioned facing the drive side space E1 and is pressed against the outer surface of the collar member 37, preventing leakage of the lubricating oil filling the drive side space E1.

[0028] A garter spring 48 is attached to the outer circumference of the lip portion 47. The garter spring 48 has the function of increasing the fastening force of the lip portion 47 by pressing it radially inward, thereby improving the sealing performance of the drive unit side seal member 42. The garter spring 48 is a steel coil spring and is formed in an annular shape.

[0029] As shown in Figure 5, the output side seal member 43 is positioned on the output side space E2 side of the drive side seal member 42 so as to provide a small gap G1 between it and the drive side seal member 42 in the axial direction of the pinion gear 30, and is a pressure-resistant oil seal capable of withstanding the pressure of the lubricating oil in the output side space E2. The output side seal member 43 has a seal body 55, a reinforcing ring 56, a lip portion 57, and a gutter spring 58. The seal body 55, which partitions the space of the through hole 31 in the second housing body 19, 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 the reinforcing ring 56, which also has 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.

[0030] As shown in Figure 5, a lip portion 57 is provided on the inner circumference of the seal body 55. The lip portion 57 slides against the outer surface of the collar member 37 and is formed to protrude in a mountain shape from the inner circumference 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 and is pressed against the outer surface of the collar member 37, preventing leakage of the lubricating oil filling the output side space E2.

[0031] A garter spring 58 is attached to the outer circumference of the lip portion 57. The garter spring 58 presses the lip portion 57 radially inward, increasing the fastening force of the lip portion 57 and improving the sealing performance of the output side sealing member 43. The garter spring 58 is a steel coil spring and is formed in an annular shape.

[0032] Drive unit side sealing member 42 and output Department Side sealing member 43 A minute gap G1 is formed between them. Gap G2 is demarcated by the outer surface of the color member 37 and the lip portions 47 and 57. Furthermore, gap G3 is demarcated by the second housing body 19 and the seal bodies 45 and 55. Gap G1 is in communication with gaps G2 and G3. Gaps G1 to G3 are spaces isolated from the drive side space E1 and the output side space E2.

[0033] As shown in Figure 4, the second housing body 19 has a communication passage 60 that connects the through hole 31 to the outside. The communication passage 60 extends vertically within the second housing body 19. It has a first passage section 63 having a through hole side opening 61, and a second passage section 64 that communicates with the first passage section 63 and has an outer opening 62. The through hole side opening 61 is formed on the hole wall surface of the through hole 31 in the second housing body 19, is located between the drive unit side sealing member 42 and the output unit side sealing member 43, and faces the gaps G1 and G3. The outer opening 62 is located below the through hole side opening 61 and is formed on the outer surface of the second housing body 19. In this embodiment, the outer opening 62 is located at a height of about 30 cm from the road surface.

[0034] The diameter of the hole in the second passage 64 is larger than the diameter of the hole in the first passage 63, that is, the diameter of the hole in the first passage 63 is smaller than the diameter of the hole in the second passage 64. The diameter of the hole in the first passage 63 is the same as the diameter of the through-hole side opening 61, and the diameter of the hole in the second passage 64 is the same as the diameter of the outer opening 62. The diameter of the through-hole side opening 61 is set to be smaller than the axial length of the gap G3. Therefore, outside air from the second housing body 19 can enter the gap G3. Since gap G3 communicates with gap G1, and gap G1 communicates with gap G2, outside air can enter gaps G1 and G2. By forming the communication passage 60 in the second housing body 19, the negative pressure in the gaps G1 to G3 as spaces in the shaft seal portion 41 is relieved, and foreign matter is prevented from entering the spaces in the shaft seal portion 41.

[0035] Next, the operation of the drive force transmission device 10 according to this embodiment will be described. When the electric forklift is moving, a pair of left and right electric motors 14 are driven. When the motor shafts 22 of the electric motors 14 rotate, the motor gears 23 rotate integrally with the motor shafts 22. The rotation of the motor gears 23 is transmitted to the first reduction gear 26, and the rotation of the first reduction gear 26 is transmitted to the second reduction gear 29 which meshes with the first reduction gear 26. The rotation transmitted from the motor gears 23 to the second reduction gear 29 is reduced according to the reduction ratio. As the second reduction gear 29 rotates, the pinion gear 30 which is spline-fitted with the second reduction gear 29 rotates.

[0036] The rotation of the pinion gear 30 causes the ring gear 40, which meshes with the pinion gear 30, to rotate, and the right axle 17 rotates integrally with the ring gear 40. The rotation of the right axle 17 is transmitted to the left axle 17 via the differential gear 38 and a differential gear (not shown) that meshes with the differential gear 38. As the left and right axles 17 rotate, the drive wheels rotate, and the electric forklift moves.

[0037] The low-viscosity lubricant filling the drive-side space E1 lubricates the sliding parts of the motor gear 23, the first reduction gear 26, the second reduction gear 29, and so on. The high-viscosity lubricant filling the output-side space E2 lubricates the sliding parts of the pinion gear 30's gear portion 33, the ring gear 40, the differential gear 38, the collar member 37, and so on. The through-hole 31 in the second housing body 19 connects the drive-side space E1 and the output-side space E2, but the shaft seal portion 41 seals the space between the drive-side space E1 and the output-side space E2. In other words, the drive-side space E1 and the output-side space E2 are separated by the shaft seal portion 41 in the through-hole 31.

[0038] The drive-side sealing member 42 of the shaft seal portion 41 prevents low-viscosity lubricating oil from flowing out of the drive-side space E1 to the output-side space E2. The output-side sealing member 43 of the shaft seal portion 41 prevents high-viscosity lubricating oil from flowing out of the output-side space E2 to the drive-side space E1. Because a gap G1 exists between the drive-side sealing member 42 and the output-side sealing member 43, gap G2 communicates with the communication passage 60 via gaps G1 and G3. The output-side sealing member 43 and the drive-side sealing member 42 slide against the outer circumferential surface of the collar member 37. Since gap G2 communicates with the communication passage 60 via gaps G1 and G3, gap G2 maintains atmospheric pressure. In other words, the pressure in gap G2 never drops below atmospheric pressure. Therefore, the shaft seal portion 41 is hardly ever pressed against the collar member 37 by negative pressure. Furthermore, even if the shaft seal portion 41 is pressed against the collar member 37, the gaps G1 to G3 become atmospheric pressure, and the pressing is eliminated.

[0039] However, foreign matter such as dust and water may enter the connecting passage 60 from the outer opening 62. Since the connecting passage 60 is a hole that penetrates vertically in the second housing body 19, even if foreign matter enters the connecting passage 60 from the outer opening 62, the foreign matter is likely to fall due to its own weight and will not reach the through-hole side opening 61. Also, since the hole diameter of the first passage section 63 is smaller than the hole diameter of the second passage section 64, it is difficult for foreign matter to enter the first passage section 63. Therefore, there is almost no risk of foreign matter accumulating in the gap G2, and a decrease in the durability of the shaft seal section 41 is avoided.

[0040] The power transmission device 10 of this embodiment provides the following effects. (1) The through-hole side opening 61 of the communication passage 60 is formed on the hole wall surface of the through-hole 31 in the second housing body 19, is located between the drive-side sealing member 42 and the output-side sealing member 43, and faces the gap between the drive-side sealing member 42 and the output-side sealing member 43. The outer opening 62 is located below the through-hole side opening 61 and is formed on the outer surface of the second housing body 19. As a result, the gap G1 provided between the drive-side sealing member 42 and the output-side sealing member 43 in the axial direction of the pinion gear 30 is in communication with the outside. Therefore, even when the pinion gear 30 rotates, the gaps G1 to G3 do not become negative pressure. In addition, because the outer opening 62 of the communication passage 60 is located below the through-hole side opening 61, foreign matter that enters the communication passage 60 is more likely to fall downwards, and foreign matter is less likely to enter the gap G3 of the shaft seal portion 41. Therefore, the function of the shaft seal portion 41 and the durability required for the shaft seal portion 41 can be maintained.

[0041] (2) The connecting passage 60 has a first passage section 63 having a through-hole side opening 61, and a second passage section 64 communicating with the first passage section 63 and having an outer opening 62. The diameter of the hole in the second passage section 64 is larger than the diameter of the hole in the first passage section 63. As a result, the diameter of the hole in the second passage section 64 is larger than the diameter of the hole in the first passage section 63, so foreign matter is more likely to fall downward in the second passage section 64 and less likely to enter in the first passage section 63.

[0042] (3) The drive unit 11 includes an electric motor 14 for driving the forklift and a reduction mechanism 15 for reducing 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 second housing body 19 and a differential mechanism 16 for distributing driving force to the pair of left and right axles 17. Therefore, even if lubricating oils of different viscosities are filled in the drive unit 11 and the output unit 12, the axle seal portion 41 prevents the lubricating oils from mixing. Furthermore, in the axle seal portion 41 of the drive force transmission device 10 of a forklift, where space is often constrained, the generation of negative pressure can be prevented without increasing its size.

[0043] (4) A pair of bearings 35 and 36 are arranged in the axial direction of the pinion gear 30 in the through hole 31. The pinion gear 30 has a shaft portion 32 that is rotatably supported by the pair of bearings 35 and 36, and a cylindrical collar member 37 fixed to the shaft portion 32 so as to be located between the pair of bearings 35 and 36 in the through hole 31. The shaft seal portion 41 slides against the collar member 37. Therefore, since the collar member 37 is fixed to the shaft portion 32 so as to be located between the pair of bearings 35 and 36, and the shaft seal portion 41 slides against the collar member 37, a decrease in the sealing function due to play in the shaft portion 32 can be suppressed.

[0044] (5) Since negative pressure in the shaft seal portion 41 can be avoided, wear caused by pressing the drive-side seal member 42 and the output-side seal member 43 against each other due to negative pressure can be suppressed, and a decrease in durability can be prevented. As a result, the shaft seal portion 41 can prevent the low viscosity lubricant in the drive-side space E1 from mixing with the high viscosity lubricant in the output-side space E2.

[0045] (modified version) Next, a modified version of the power transmission device will be described. In this modified version, as shown in Figure 6, a check valve 70 is provided in the communication passage 60 formed in the second housing body 19. The check valve 70 is a duckbill valve made of a rubber-based material and opens when the pressure in the communication passage 60 falls below atmospheric pressure. Therefore, when the check valve 70 is open, air flows from the outside into the communication passage 60, but when it is closed, the outside and the communication passage 60 are blocked. This modified version can better prevent the entry of foreign matter. The check valve 70 is a duckbill valve, but any check valve that allows air to flow from the outside towards the gap G2 is acceptable, for example, a ball-type or diaphragm-type check valve may be used.

[0046] It should be noted that the present invention is not limited to the above embodiments (including modified examples), and various modifications are possible within the scope of the spirit of the invention. For example, it may be modified as follows.

[0047] ○ In the above embodiments (including modifications), the vertically formed passage has a first connecting section and a second connecting section, and the hole diameter of the first connecting section is smaller than the hole diameter of the second connecting section, but the embodiment is not limited to this. The passage may be formed with a hole of the same diameter as the opening on the through-hole side, for example. Furthermore, the direction of the passage is not limited to the vertical direction, but at least the outer opening must be located below the through-hole side opening, and for example, the passage may be inclined with respect to the vertical direction. ○ In the above embodiment, an example of a rotating body (pinion gear) equipped with a collar member has been described, but the invention is not limited to this. The rotating body may be a rotating body without a collar member. In this case, for example, the shaft seal portion may slide against the boss portion of the reduction gear provided on the rotating body. Alternatively, the shaft seal portion may slide against the outer circumferential surface of the rotating body. ○ The above embodiments (including modified examples) illustrate a power transmission device for an electric forklift as an industrial vehicle, but are not limited thereto. The present invention is not limited to industrial vehicles, but can be any power transmission device that outputs power from a power source to an output unit. [Explanation of Symbols]

[0048] 10. Power transmission device 11 Drive unit 12 Output section 13 Housing 14 Electric motor 15 Reduction mechanism 16 Differential mechanism 17 axles 18. First Housing Unit 19. Second Housing Unit 20 Third Housing Unit 23 Motor Gear 26 First reduction gear 29 Second reduction gear 30 Pinion Gear (Rotating Body) 31 Through hole 35, 36 Bearings 37 Color components 41 Shaft seal section 42 Drive unit side sealing member 43 Output side sealing member 60 Communication path 61 Through hole side opening 62 Outer opening 63 1st passage section 64 2nd passage section 70 Check valve E1 Drive side space E2 Output side space G1, G2, G3 gaps P, Q, R axis center

Claims

1. A drive unit that generates driving force, An output unit that outputs the driving force of the aforementioned drive unit, A housing that forms a drive-side space for housing the drive unit and an output-side space for housing the output unit, A rotating body connected to the drive unit and transmitting driving force to the output unit, The housing is provided with a through hole through which the rotating body is inserted, It has a shaft seal portion provided in the through hole and sliding with the rotating body, The aforementioned shaft seal portion is The drive unit side sealing member located on the drive unit side, The rotating body has an output-side sealing member located on the output-side so as to provide a gap with the drive-side sealing member in the axial direction, The housing is a drive force transmission device having a communication passage that connects the through hole to the outside, The aforementioned connecting passage is A through-hole opening is formed on the wall surface of the through-hole in the housing, located between the drive-side sealing member and the output-side sealing member, and facing the gap. An outer opening located below the through-hole side opening and formed on the outer surface of the housing, The first passage section having the through-hole side opening, It has a second passage that communicates with the first passage and has the outer opening, A driving force transmission device characterized in that the diameter of the hole in the second passage is larger than the diameter of the hole in the first passage.

2. The drive unit side sealing member and the output unit side sealing member each have a sealing body, a lip portion, and a reinforcing ring, The gap is a space that is separated from the drive-side space and the output-side space. The drive force transmission device according to claim 1, characterized in that the reinforcing ring is provided on each of the seal bodies so as not to be exposed in the gap.

3. The drive force transmission device according to claim 1 or 2, characterized in that the communication passage has a check valve that allows air to flow from the outside toward the gap.

4. The aforementioned drive unit is Electric motors for industrial vehicles, The electric motor is equipped with a reduction mechanism for reducing the rotational force of the electric motor, The output unit is, A pair of left and right axles rotatably supported in the housing, The power transmission device according to claim 1 or 2, further comprising a differential mechanism for distributing power to the left and right pair of axles.

5. In the through hole, a pair of bearings are arranged in the axial direction of the rotating body. The rotating body comprises a rotating body body that is rotatably supported by the pair of bearings, The rotating body has a cylindrical collar member fixed to the rotating body so as to be located between the pair of bearings in the through hole, The drive force transmission device according to claim 1 or 2, characterized in that the shaft seal portion slides against the collar member.

Images