JP2007292244A - Transmission unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simply structured transmission unit which can effectively keep a lubricity of gear transmission mechanism while effectively preventing a transmission efficiency of the above-mentioned transmission mechanism from decreasing, in a transmission unit in which the gear transmission mechanism is housed inside a gear casing which can store oil. <P>SOLUTION: A transmission unit 200 comprises a first transmission shaft 210, a second transmission shaft 220, a gear transmission mechanism 230, and a gear casing 240. The gear casing 240 includes a lower aperture 241 and an upper aperture 242; and the upper aperture 242 and the lower aperture 241 are processed in fluid connection, so that the oil inside the gear casing 240 sent out from the lower aperture 241 by utilizing a revolution of the lowest gear 233 can be introduced inside the gear casing 240 again from the upper aperture 242 directly or indirectly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transmission unit applied to a work vehicle or the like.

It is known to insert a gear transmission mechanism (for example, a gear train) accommodated in a gear case into a transmission path in a work vehicle.
For example, in order to output the output of the flywheel main body from a position displaced from the axial center position of the flywheel main body, such a configuration is adopted (see Patent Document 1 below).

Incidentally, the lubrication of the gear transmission mechanism accommodated in the gear case is generally performed by the stored oil in the gear case.
However, if the amount of stored oil in the gear case is increased, the gear transmission mechanism can be sufficiently lubricated, but the stored oil becomes a stirring resistance for the gear transmission mechanism, and the transmission efficiency of the gear transmission mechanism is deteriorated.
On the other hand, if the amount of oil stored in the gear transmission mechanism is reduced, deterioration of the transmission efficiency of the gear transmission mechanism due to the stored oil can be prevented, but the lubricity of the gear transmission mechanism is deteriorated.
JP 2005-106231 A

  The present invention has been made in view of the prior art, and in a transmission unit in which a gear transmission mechanism is housed in a gear case capable of storing oil, while effectively preventing deterioration of the transmission efficiency of the gear transmission mechanism, An object of the present invention is to provide a transmission unit with a simple structure capable of effectively maintaining the lubricity of the gear transmission mechanism.

  In order to achieve the above object, the present invention provides a first transmission shaft operatively connected to a drive source, a second transmission shaft disposed substantially parallel to the first transmission shaft, and the first transmission shaft. A gear transmission mechanism for transmitting rotation to the second transmission shaft, the gear transmission mechanism including a plurality of transmission gears, the first and second transmission shafts rotatably supported about an axis, and the gear transmission mechanism A transmission unit including an oil storage gear case that stores oil, wherein the gear case is based on a lowermost point of a lowermost gear that is positioned at a lowermost position among the plurality of transmission gears constituting the gear transmission mechanism. A lower opening communicating the internal space of the gear case with the outside at a portion located downstream in the rotational direction of the lowermost gear, and the internal space and the external of the gear case above the oil level in the gear case. Communicating above The upper opening and the lower opening are configured so that oil in the gear case fed from the lower opening using rotation of the lowermost gear is directly or indirectly from the upper opening into the gear case. A transmission unit is provided which is fluidly connected so as to be reintroduced into the vehicle.

As a specific aspect of the transmission unit according to the present invention, for example, the following aspect can be cited. That is,
(A) A mode in which the upper opening is arranged so that oil introduced from the upper opening flows toward the uppermost gear among the plurality of transmission gears,
(B) an aspect further comprising a piping member having a proximal end fluidly connected to the lower opening and a distal end fluidly connected to the upper opening, preferably the proximal end fluidly connected to the lower opening An external reservoir fluidly connected to a first pipe and a distal end portion of the first pipe, the external reservoir disposed above the upper opening, and a base end portion fluidly connected to the external reservoir and a distal end A portion further comprising a second pipe fluidly connected to the upper opening,
(C) The gear case is opposed to a first end wall and a second end wall facing the end surface on one side and the end surface on the other side of the plurality of transmission gears, and a peripheral portion of the plurality of transmission gears. A first side surface located on the downstream side in the rotation direction of the lowermost gear with respect to the lowermost point of the peripheral wall, the peripheral wall extending between the first and second end walls. Further, the gear case is in contact with the inner surface of the first side surface of the peripheral wall so that the base end portion covers the upper side of the lower opening. And an upper guide wall that is close to the peripheral portion of the lowermost gear so that the front end portion faces a portion of the peripheral portion of the lowermost gear that is located downstream of the lowest point in the rotational direction. Embodiment
(D) The gear case is opposed to a first end wall and a second end wall that respectively face one end face and the other end face of the plurality of transmission gears, and a peripheral edge portion of the plurality of transmission gears. A first side surface located on the downstream side in the rotation direction of the lowermost gear with respect to the lowermost point of the peripheral wall, the peripheral wall extending between the first and second end walls. Further, the gear case is in contact with the inner surface of the first side surface of the peripheral wall so that the base end portion covers the lower side of the lower opening. The lower end of the lowermost gear extends below the lowermost point of the lowermost gear and extends upstream of the lowermost gear in the rotational direction of the lowermost gear. The guide wall is closest to the peripheral edge of the lowermost gear at the lowest point and Embodiments wherein is separated from the peripheral edge of the outermost lower gear toward the rotational direction upstream and downstream of the lowermost gear from,
(E) A mode in which at least one of the modes (a) to (d) is combined.

  In the aspect of (e) including the aspects of (d) and (d), the first guide of the peripheral wall is such that the lower guide wall is located between the lowermost gear and the bottom surface of the peripheral wall. The rib may be provided continuously to the side surface and at least one of the first and second end walls.

  According to the transmission unit of the present invention, the upper opening and the lower opening in the gear case are directly or indirectly caused by the oil in the gear case sent from the lower opening using the rotation of the lowermost gear. Since it is fluidly connected so as to be re-introduced into the gear case from the upper opening, a pumping action in which oil is sucked from the lower opening and oil is discharged from the upper opening by the rotational operation of the lowermost gear. Can be played. Accordingly, when the lowermost gear rotates, oil reintroduced into the gear case from the upper opening can be supplied to the gear transmission mechanism, thereby effectively reducing the transmission efficiency of the gear transmission mechanism. It is possible to effectively maintain the lubricity of the gear transmission mechanism.

  Further, when the upper opening is arranged so that oil introduced from the upper opening flows toward the uppermost gear of the plurality of transmission gears, the upper opening The introduced oil can be introduced into the gear transmission mechanism as a whole, and good lubricity of the gear transmission mechanism can be obtained accordingly.

  A first pipe having a proximal end fluidly connected to the lower opening; and an external reservoir fluidly connected to a distal end of the first pipe, the external reservoir being disposed above the upper opening; And a second pipe having a proximal end fluidly connected to the external reservoir and a distal end fluidly connected to the upper opening, the oil sent from the lower opening toward the upper opening Once stored in the external reservoir, oil can be stably introduced into the gear case from the upper opening.

  The gear case includes the first end wall and the second end wall, and the peripheral wall, and the lower opening is downstream in the rotational direction of the lowermost gear with respect to the lowest point of the peripheral wall. The gear case is provided on the first side surface located on the side so as to be substantially at the same height as the lowest point, and the gear case has a first end of the peripheral wall so that a base end portion covers an upper side of the lower opening. The tip is brought into contact with the inner surface of the side surface, and the tip is brought close to the peripheral portion of the lowermost gear so as to face the portion of the peripheral portion of the lowermost gear that is located downstream of the lowest point in the rotational direction. In the case where the upper guide wall is provided, the stored oil flowing to the downstream side in the rotation direction of the lowermost gear as the lowermost gear rotates can be guided to the lower opening by the upper guide wall. .

The gear case includes the first end wall and the second end wall, and the peripheral wall, and the lower opening is downstream in the rotational direction of the lowermost gear with respect to the lowest point of the peripheral wall. The gear case is provided on the first side surface located on the side so as to be substantially the same height as the lowest point, and the gear case further includes a first end of the peripheral wall so that a base end portion covers a lower side of the lower opening. A lower guide wall which is in contact with the inner surface of the side surface and whose tip extends below the lowermost point of the lowermost gear and extends beyond the lowermost point upstream in the rotational direction of the lowermost gear; The lower guide wall is closest to the peripheral edge portion of the lowermost gear at the lowest point, and the lowermost guide wall moves from the lowest point toward the upstream side and the downstream side in the rotational direction of the lowermost gear. When separated from the peripheral edge of the lower gear, the rotation of the lowermost gear The serial pumping action can be accelerated by the lower guide wall.
In such a configuration, the lower guide wall is located on the first side surface of the peripheral wall and at least one of the first and second end walls so as to be positioned between the lowermost gear and the bottom surface of the peripheral wall. If the ribs are provided continuously, the space for storing oil can be secured below the ribs while maintaining the pump action, and the amount of oil stored in the gear case can be increased accordingly.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic side view of a working vehicle 100 (here, a passenger tractor) to which an example 200 of a transmission unit according to the present invention is applied.

A working vehicle 100 shown in FIG. 1 is a pair of left and right body frames 1, 1 arranged at a predetermined interval in the vehicle width direction, and extends in the vehicle front-rear direction (X direction in the figure). 1 and 1, and the body frame 1, 1 is provided with a drive source 2 (in this case, an engine) and a transmission case 3 that are separated from each other in the front-rear direction. X is configured to be able to transmit to a pair of left and right steering wheels and a pair of left and right steering wheels respectively disposed on one side X1 and the other side X2. In the present embodiment, the pair of left and right steering wheels are the front wheels 4 and 4, and the pair of left and right steering wheels are the rear wheels 5 and 5.
That is, a front axle 4a that supports the front wheels 4 and 4 is supported at the front of the body frame 1 and 1, and supports the rear wheels 5 and 5 from the transmission case 3 outward in the vehicle width direction. The rear axle 5a is projected.
In the present embodiment, an engine is used as the drive source 2, but an electric motor may be used.

In addition, the working vehicle 100 is configured to be provided with a working machine.
A PTO shaft 18 for outputting a driving force to the work machine when the work machine is attached is provided at the rear end of the mission case 3 so as to protrude rearward.

  In the working vehicle 100, the drive source 2 is disposed inside the hood 6 at the front of the traveling machine body. A driving unit case 9 is disposed behind the bonnet 6, and a steering column case 7 is provided on the driving unit case 9. A steering steering 8 is disposed above the steering column case 7, and a driver's seat 10 is disposed behind the steering steering 8 and above the transmission case 3.

  A step base 12 is provided from the lower front side of the driver seat 10 to the driver section case 9, and the rear wheel fender 11 is provided behind the step base 12.

The drive shaft 2 a in the drive source 2 is a first transmission shaft 210 (to be described later) in the transmission unit 200.
Here, the first transmission shaft 210 of the transmission unit 200 is the drive shaft 2a in the drive source 2 and is directly connected to the drive source 2. However, a transmission mechanism is connected to the drive source 2. You may make it connect indirectly via.

Here, a flywheel main body 2b is mounted on the drive shaft 2a of the drive source 2.
A flywheel cover 13 covering the flywheel main body 2b is detachably provided at the rear part of the drive source 2, and the drive-side power output from the drive source 2 is provided at the rear part of the flywheel cover 13. The transmission unit 200 is provided to transmit the gear to the driven side (here, the transmission case 17 via a telescopic transmission shaft 17 provided with universal joints 17a at both ends). The transmission unit 200 will be described in detail later.

In the transmission case 3, a transmission and a PTO clutch mechanism (not shown) are provided.
The transmission includes a hydraulic transmission and a mechanical transmission mechanism.
The hydraulic transmission includes a hydraulically operable power reverser that switches between forward rotation and reverse rotation of the rear wheels 5 and 5. This power reverser also functions as a main clutch that switches between a power transmission state in which power is transmitted from the drive source 2 to the rear wheels 5 and 5 and a power cut-off state in which power transmission to the rear wheels 5 and 5 is interrupted. It is like that.

  The mechanical transmission mechanism includes a main transmission mechanism and a sub-transmission mechanism for switching to each vehicle speed mode, and the PTO clutch mechanism has a power transmission state in which power is transmitted from the drive source 2 to the PTO shaft 18. The hydraulic clutch switches between a power cut-off state in which power transmission to the PTO shaft 18 is cut off.

Next, the transmission unit 200 will be described.
2 is a schematic cross-sectional view centering on the transmission unit 200 portion in the working vehicle 100, and FIG. 3 is a schematic rear view centering on the transmission unit 200 portion shown in FIG. In FIG. 3, a hydraulic gear pump 280, which will be described later, is not shown.

Here, the transmission unit 200 is provided at the rear part of the flywheel cover 13 in order to transmit the power from the drive source 2 to the transmission case 3 spaced rearward from the drive source 2. .
Here, since the driver's seat 10 is disposed above the transmission case 3, when the position of the driver's seat 10 is to be lowered, the transmission unit 200 outputs the output of the flywheel body 2b, The flywheel body 2b is required to be output from a displaced position with respect to the axial center position.

That is, the transmission unit 200 includes the first transmission shaft 210 operatively connected to the drive source 2, the second transmission shaft 220 disposed substantially parallel to the first transmission shaft 210, and the first transmission. A gear transmission mechanism 230 that transmits the rotation of the shaft 210 to the second transmission shaft 220, and includes a gear transmission mechanism 230 including a plurality of transmission gears (here, three transmission gears 231, 232, and 233 are connected as described later). And a gear case 240 capable of storing oil and accommodating the gear transmission mechanism 230 while rotatably supporting the first and second transmission shafts 210 and 220.
The second transmission shaft 220 is displaced at a position displaced with respect to the axial center position of the first transmission shaft 210 (here, a position displaced below the first transmission shaft 210). Are arranged substantially in parallel with each other.

The gear case 240 has a lower opening 241 and an upper opening 242 (see FIG. 3).
The lower opening 241 is the rotational direction of the lowermost gear 233 with reference to the lowest point P of the lowermost gear 233 located at the lowermost position among the plurality of transmission gears 231 to 233 constituting the gear transmission mechanism 230. (In the direction of arrow A in FIG. 3) In the portion located downstream, the internal space of the gear case 240 communicates with the outside.
The upper opening 242 communicates the internal space of the gear case 240 with the outside above the oil level in the gear case 240 (here, the oil level L1 when the driving of the drive source 2 is stopped). is doing.

  The upper opening 242 and the lower opening 241 are configured so that the oil Q in the gear case 240 sent from the lower opening 241 using the rotation of the lowermost gear 233 is directly or indirectly from the upper opening 242. It is fluidly connected so as to be reintroduced into the gear case 240.

  By providing such a configuration, when the drive source 2 is operated, the transmission unit 200 causes the stored oil Q to move along the rotational direction A of the lowermost gear 233 by the rotational operation of the lowermost gear 233. (For example, the stored oil Q is pushed out into a tooth groove (not shown) at the peripheral edge of the lowermost gear 233, and the pushed-up stored oil Q is moved to the peripheral wall 245 of the gear case 240 (here, the lower side described later). Along the side guide wall 247) with respect to the lowermost point P as a reference, and is transported downstream in the rotational direction A of the lowermost gear 233), so that the stored oil Q is referred to the lowermost point P as a reference. A pumping action that is sucked into the lower opening 241 located on the downstream side in the rotation direction A of the lowermost gear 233 and discharged from the upper opening 242 fluidly connected to the lower opening 241 can be achieved. Therefore, when the lowermost gear 233 rotates, the oil Q re-introduced into the gear case 240 from the upper opening 242 can be supplied to the gear transmission mechanism 230, and thereby the gear transmission mechanism 230. It is possible to effectively maintain the lubricity of the gear transmission mechanism 230 while effectively preventing the transmission efficiency from deteriorating.

Specifically, the gear transmission mechanism 230 includes a first transmission gear 231 provided in the first transmission shaft 210 so as not to rotate relative to the first transmission shaft 210 and a second transmission gear 233 provided in the second transmission shaft 220 so as not to rotate relative thereto. And a third transmission gear 232 that meshes with the first transmission gear 231 and the second transmission gear 233.
More specifically, the first and second transmission shafts 210 and 220 are supported by the gear case 240 directly or indirectly (here, via bearing members b1 and b2) so as to be rotatable about the axis. .
The third transmission gear 232 is provided in a relatively non-rotatable manner with respect to the third transmission shaft 232a that is substantially parallel to the first transmission shaft 210 and the second transmission shaft 220, and the third transmission shaft 232a. Is supported by the gear case 240 directly or indirectly (in this case, via the bearing member b3) so as to be rotatable about the axis. However, the present invention is not limited to this, and the third transmission gear 232 is rotatable about the axis directly or indirectly (for example, via a bearing member) to the third transmission shaft supported by the gear case 240. Also good.

  The third transmission gear 232 is a single gear here, but may be a gear train in which a plurality of gears mesh with each other. In addition, the gear transmission mechanism 230 is a gear train here, but instead, the first transmission gear provided on the first transmission shaft so as not to rotate relative to the first transmission shaft and the second transmission shaft cannot be rotated relative to the first transmission gear. A second transmission gear provided and a chain wound around the first transmission gear and the second transmission gear may be included.

In the present embodiment, in the upper opening 242, the oil Q introduced from the upper opening 242 flows toward the uppermost gear 231 located at the uppermost position among the plurality of transmission gears 231, 232, and 233. (Here, at the top of the gear case 240).
With such a configuration, the transmission unit 200 can introduce the oil Q re-introduced into the gear case 240 from the upper opening 242 into the gear transmission mechanism 230 as a whole, and the gear transmission accordingly. Good lubricity of the mechanism 230 can be obtained.

In the present embodiment, the transmission unit 200 includes a first pipe 250, an external reservoir 260, and a second pipe 270 in addition to the above configuration.
The first pipe 250 has a base end 251 fluidly connected to the lower opening 241.
The external reservoir 260 is fluidly connected to the distal end 252 of the first pipe 250 and is disposed above the upper opening 242.
The second pipe 270 has a proximal end portion 271 fluidly connected to the external reservoir 260 and a distal end portion 272 fluidly connected to the upper opening 242.
With such a configuration, the transmission unit 200 can temporarily store the oil sent from the lower opening 241 toward the upper opening 242 in the external reservoir 260, and thereby, the gear case from the upper opening 242. A predetermined amount of oil can be stably introduced into 240.
Here, the external reservoir 260 has a first connection port 261 and a second connection port 262 disposed below the first connection port 261. The first connection port 261 is fluidly connected to the distal end portion 252 of the first piping 250, and the second connection port 262 is fluidly connected to the proximal end portion 271 of the second piping 270.

In the present embodiment, the gear case 240 includes a first end wall 243 and a second end wall 244 (FIG. 2) that face one end surface and the other end surface of the plurality of transmission gears 231, 232, 233, respectively. And a peripheral wall 245 (see FIG. 3) extending between the first and second end walls 243 and 244 so as to face the peripheral edge portions of the plurality of transmission gears 231, 232 and 233.
Here, the gear case 240 is formed integrally with the flywheel cover 13 at a portion located on the flywheel cover 13 side.

The lower opening 241 has substantially the same height as the lowest point P on the first side surface 245a located on the downstream side in the rotation direction A of the lowermost gear 233 with respect to the lowest point P of the peripheral wall 245. It is provided as follows.
The gear case 240 is brought into contact with the inner surface of the first side surface 245a of the peripheral wall 245 so that the base end portion 246a covers the upper side of the lower opening 241 and the distal end portion 246b is a peripheral edge of the lowermost gear 233. An upper guide wall 246 that is close to the peripheral edge of the lowermost gear 233 is provided so as to face a portion that is located downstream of the lowest point P in the rotational direction A.
With this configuration, the transmission unit 200 causes the upper guide wall 246 to store the stored oil Q that flows downstream in the rotation direction A of the lowermost gear 233 as the lowermost gear 233 rotates. 241 can be guided.

Further, in the present embodiment, the gear case 240 is brought into contact with the inner surface of the first side surface 245a of the peripheral wall 245 so that the base end portion 247a covers the lower side of the lower opening 241 and the distal end portion 247b is A lower guide wall 247 is provided below the lowermost point P of the lowermost gear 233 and extends beyond the lowermost point P to the upstream side in the rotational direction A of the lowermost gear 233.
The lower guide wall 247 is closest to the peripheral edge of the lowermost gear 233 at the lowermost point P, and from the lowermost point P to the upstream side and the downstream side in the rotational direction A of the lowermost gear 233. As it goes, it is separated from the peripheral edge of the lowermost gear 233.
By providing such a configuration, the transmission unit 200 can promote the pump action by the rotation of the lowermost gear 233 by the lower guide wall 247.

Here, the upper guide wall 246 and the lower guide wall 247 are ribs provided continuously to the first side surface 245a of the peripheral wall 245.
For example, the lower guide wall 247 may be the bottom surface of the peripheral wall 245, but as shown in FIG. 3, the lower guide wall 247 is positioned between the lowermost gear 233 and the bottom surface of the peripheral wall 245. When the rib is provided continuously to the first side surface 245a of the peripheral wall 245 and at least one of the first and second end walls 243 and 244, oil is provided below the rib 247 while maintaining the pump action. Can be secured, and the amount of oil stored in the gear case 240 can be increased accordingly.

Further, in the present embodiment, the gear case 240 is provided with an oil inspection window 248 through which the oil level of the stored oil Q stored in the gear case 240 can be visually recognized from the outside.
By providing such a configuration, the transmission unit 200 can easily recognize the amount of oil Q stored in the gear case 240 from the outside.
Here, the oil inspection window 248 can visually recognize the oil level L1 when the drive of the drive source 2 is stopped. However, the oil level is not limited thereto, and the oil level when the drive source 2 is operating may be visible together with the oil level L1 or instead of the oil level L1. In addition, the entire oil level may be visible.

The transmission unit 200 is provided with a hydraulic gear pump 280 as shown in FIG.
Here, the hydraulic gear pump 280 supplies hydraulic oil for various hydraulic mechanisms (for example, the hydraulic transmission, the PTO clutch mechanism, and the power steering valve device) in the transmission case 3 that follows the second transmission shaft 220. It has come to be used as an industrial pump.

FIG. 4 is a schematic rear view of the hydraulic gear pump 280.
The hydraulic gear pump 280 includes a drive shaft 281 operatively connected to the first transmission shaft 210, a drive side gear 282 provided so as not to rotate relative to the drive shaft 281, and a driven side meshing with the drive side gear 282. A gear 283 and a pump case 284 that supports the drive shaft 281 to be rotatable about an axis and accommodates the drive side gear 282 and the driven side gear 283 are provided.
The pump case 284 has an input port 284a fluidly connected to a hydraulic oil storage tank (not shown) via an input side pipe C1, and has an engagement point R between the drive side gear 282 and the driven side gear 283. An input port 284a disposed on the upstream side of the rotation direction of the gears 282 and 283 (in the direction of arrow B in FIG. 4) and an output port 284b fluidly connected to the various hydraulic mechanisms via an output side pipe C2. In addition, an output port 284b is provided on the downstream side in the rotation direction B of the gears 282 and 283 across the meshing point R.

By providing such a configuration, the hydraulic gear pump 280 causes the hydraulic oil S to be sucked from the input port 284a and discharged from the output port 284b by the rotational operation of the gears 282, 283, and the output thereof. The hydraulic oil S discharged from the port 284b is used as hydraulic oil for the various hydraulic mechanisms (for example, the hydraulic transmission, the PTO clutch mechanism, and the power steering valve device) in the transmission case 3. Yes.
The hydraulic gear pump 280 may be provided near the lower side of the steering steering 8 (preferably directly below the steering steering 8). By doing so, the hydraulic piping from the hydraulic gear pump 280 to the power steering valve device can be made as short as possible.

FIG. 1 is a schematic side view of a working vehicle (here, a riding tractor) to which an example of a transmission unit according to the present invention is applied. 2 is a schematic cross-sectional view centering on a transmission unit portion in the working vehicle shown in FIG. FIG. 3 is a schematic rear view mainly showing the transmission unit portion shown in FIG. FIG. 4 is a schematic rear view of the hydraulic gear pump provided in the transmission unit.

Explanation of symbols

2 ... Drive source 200 ... Transmission unit 210 ... First transmission shaft 220 ... Second transmission shaft
230 ... Gear transmission mechanism 231, 232, 233 ... Multiple transmission gears
233 ... Lowermost gear 240 ... Gear case 241 ... Lower opening 242 ... Upper opening
243 ... first end wall 244 ... second end wall 245 ... peripheral wall 245a ... first side surface of the peripheral wall
246: upper guide wall 246a: base end portion of the upper guide wall 246b ... distal end portion of the upper guide wall
247: Lower guide wall 247a: Base end portion of the lower guide wall 247b ... Front end portion of the lower guide wall
250 ... first piping 251 ... base end portion of the first piping 252 ... tip portion of the first piping
260 ... External reservoir 270 ... Second pipe 271 ... Base end of second pipe
272 ... The tip of the second pipe L1 ... Oil level P ... The lowest point of the lowermost gear

Claims (5)

A first transmission shaft operatively connected to a drive source; a second transmission shaft disposed substantially parallel to the first transmission shaft; and a gear transmission for transmitting rotation of the first transmission shaft to the second transmission shaft. A mechanism comprising a gear transmission mechanism including a plurality of transmission gears, and a gear case capable of storing oil and supporting the first and second transmission shafts so as to be rotatable about an axis and accommodating the gear transmission mechanism. A transmission unit,
The gear case is a portion of the plurality of transmission gears constituting the gear transmission mechanism at a portion located on the downstream side in the rotation direction of the lowermost gear with reference to the lowest point of the lowermost gear located at the lowermost position. A lower opening that communicates the internal space and the outside, and an upper opening that communicates the internal space of the gear case with the outside above the oil level in the gear case,
In the upper opening and the lower opening, the oil in the gear case fed from the lower opening using the rotation of the lowermost gear is reintroduced directly or indirectly into the gear case from the upper opening. A transmission unit characterized in that it is fluidly connected to.   A first pipe whose base end is fluidly connected to the lower opening; an external reservoir fluidly connected to a distal end of the first pipe, the external reservoir disposed above the upper opening; The transmission unit according to claim 1, further comprising a second pipe having an end portion fluidly connected to the external reservoir and a distal end portion fluidly connected to the upper opening. The gear case includes a first end wall and a second end wall facing the end surface on one side and the end surface on the other side of the plurality of transmission gears, respectively, and the first end wall so as to face a peripheral portion of the plurality of transmission gears. And a peripheral wall extending between the second end walls,
The lower opening is provided on the first side surface located on the downstream side in the rotational direction of the lowermost gear with respect to the lowermost point of the peripheral wall so as to be substantially the same height as the lowermost point.
Further, the gear case is in contact with the inner surface of the first side surface of the peripheral wall so that the base end portion covers the upper side of the lower opening, and the distal end portion is the lowest point of the peripheral portion of the lowermost gear. 3. The transmission unit according to claim 1, further comprising an upper guide wall that is close to a peripheral edge portion of the lowermost gear so as to face a portion located further downstream in the rotational direction. The gear case includes a first end wall and a second end wall facing the end surface on one side and the end surface on the other side of the plurality of transmission gears, respectively, and the first end wall so as to face a peripheral portion of the plurality of transmission gears. And a peripheral wall extending between the second end walls,
The lower opening is provided on the first side surface located on the downstream side in the rotational direction of the lowermost gear with respect to the lowermost point of the peripheral wall so as to be substantially the same height as the lowermost point.
Further, the gear case is in contact with the inner surface of the first side surface of the peripheral wall so that the base end portion covers the lower side of the lower opening, and the distal end portion is below the lowest point of the lowermost gear. Having a lower guide wall extending beyond the lower point to the upstream side in the rotational direction of the lowermost gear;
The lower guide wall is closest to the peripheral edge of the lowermost gear at the lowest point, and the peripheral edge of the lowermost gear as it goes from the lowest point to the upstream and downstream sides in the rotational direction of the lowermost gear. The transmission unit according to claim 1, wherein the transmission unit is separated from the portion.   The lower guide wall is a rib connected to the first side surface of the peripheral wall and at least one of the first and second end walls so as to be positioned between the lowermost gear and the bottom surface of the peripheral wall. The transmission unit according to claim 4, wherein:

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