JP5059920B2 - Automatic transmission - Google Patents

Description

  The present invention relates to an automatic transmission including a transmission case and an oil pan in which hydraulic oil used for shifting operation, lubrication, cooling, and the like is stored.

  Conventionally, as an automatic transmission equipped with a transmission case in which hydraulic oil is stored and an oil pan, the differential oil is separated so that the hydraulic oil around the differential final gear is separated into the differential final gear side and the transmission case side. The thing which provided the baffle plate around the gear is known (for example, refer patent document 1).

Japanese Patent No. 4074278

  However, in the conventional automatic transmission, a baffle plate is provided around the differential final gear. For this reason, with the intention of increasing the support strength of the final shaft, even if an inner wall rib is formed on the differential gear inner wall along the differential final gear in the transmission case, it interferes with the baffle plate and the inner wall rib cannot be formed. There was a problem.

  Therefore, if the inner wall rib is formed as a configuration without a baffle plate, not only does the amount of stirring oil reduced by the baffle plate increase, but the inner wall rib also hinders the flow of hydraulic oil into the oil dropping hole leading to the oil pan. . For this reason, for example, when the hydraulic oil is scraped up by the differential final gear while the oil level is greatly inclined during sudden start or turning, the amount of hydraulic oil that occupies the breather space above the oil level Will increase. That is, when the amount of oil that remains in the breather space and does not return to the oil pan increases, the effective amount of hydraulic oil stored for sucking up the oil pump decreases, and the level of the oil level decreases. As described above, when the oil level is inclined while the oil level is lowered, there is a problem that the oil pump may suck air from the oil strainer.

  The present invention has been made paying attention to the above-mentioned problems, and provides an automatic transmission that can achieve shaft support strength performance, breather performance, and inclined air suction prevention performance, which are unit required performance of an automatic transmission. The purpose is to do.

To achieve the above object, an automatic transmission according to the present invention includes a transmission case, a transmission shaft having a first axis, an idler shaft having a second axis, and a final shaft having a third axis. Means provided with an oil pan, an inner wall rib, and a return channel.
The transmission case has a breather space in which hydraulic oil is stored and a space above the oil level communicates with outside air.
The transmission shaft having the first shaft center is supported by the transmission case and has a transmission mechanism for changing the input rotational speed.
The idler shaft having the second axis is supported by the case at a position above the first axis, and has an idler gear that meshes with an output gear provided on the transmission shaft.
The final shaft having the third axial center has a differential final gear that is supported by the case at a position below the first axial center and the second axial center and meshes with an idler final gear provided on the idler shaft.
The oil pan is provided in the transmission case, and has an oil strainer set in an intake port of an oil pump while accumulating the hydraulic oil.
The inner wall rib is formed on a differential gear inner wall along the differential final gear in the transmission case, and a case strength around the axis of the final shaft is determined in a wall surface region between the first axis and the third axis. Increase.
The return flow path has an oil inlet opened above the inner wall rib, and returns the hydraulic oil from the oil inlet to the oil pan.

Thus, the inner wall rib formed on the inner wall of the differential gear along the differential final gear increases the case strength around the final shaft and improves the support strength of the final shaft.
During traveling, the hydraulic oil that has moved or scattered in the breather space flows from the oil inlet that is opened above the inner wall rib, passes through the return flow path, and is returned to the oil pan.
That is, due to the rapid oil inflow from the oil inlet located above the inner wall rib, the amount of return oil from the return flow passage → The amount of oil stagnating in the breather space → The amount of scattered oil by the gear is reduced. The flow of action is repeated.
Therefore, the decrease in the effective oil amount of the hydraulic oil stored in the transmission case and the oil pan is suppressed, and the oil level of the hydraulic oil is managed so that the oil level is maintained at a predetermined level. In the state where the oil level is controlled, for example, even if the oil level is inclined due to sudden start or turning, the oil pump is prevented from sucking air from the oil strainer.
As a result, the shaft support strength performance, breather performance, and inclined air suction prevention performance, which are unit performance requirements of the automatic transmission, can be achieved together.

1 is a developed cross-sectional view illustrating an overall configuration of an automatic transmission according to a first embodiment. It is a figure which shows the transmission case seen from the converter cover side of the automatic transmission of Example 1. It is a figure which shows the transmission case seen from the transmission mechanism end cover side of the automatic transmission of Example 1. It is a figure which shows the transmission case seen from the oil pan side of the automatic transmission of Example 1. FIG. 3 is a cross-sectional perspective view taken along line AA of FIG. 2 showing a return channel of the automatic transmission according to the first embodiment. FIG. 5 is an operation explanatory diagram illustrating a hydraulic oil return operation from a return flow path in the automatic transmission according to the first embodiment.

  Hereinafter, the best mode for realizing an automatic transmission according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
FIG. 1 is a developed cross-sectional view illustrating the overall configuration of the automatic transmission according to the first embodiment. The overall configuration will be described below with reference to FIG.

  As shown in FIG. 1, the automatic transmission AT according to the first embodiment includes a transmission input shaft 4 (transmission shaft having a transmission case 1, a converter cover 2, a transmission mechanism end cover 3, and a first axis C1. ), A transmission output shaft 5 (transmission shaft) having a first axis C1, an idler shaft 6 having a second axis C2, and drive shafts 7 and 7 (final shaft) having a third axis C3. It is equipped with.

  The automatic transmission AT is a stepped automatic transmission with four forward speeds and one reverse speed applied to a front-wheel drive front-wheel drive vehicle, depending on the gear stage selected for input rotation from an engine (not shown). The speed is changed, and the engine driving force after the speed change is transmitted to the left and right front wheels.

  The transmission case 1 is called a transmission case and is a main case member that supports transmission input / output shafts 4, 5, idler shaft 6, and drive shafts 7, 7 arranged in parallel. A converter cover 2 that covers the torque converter 8 is bolted to a flange surface on one end side of the transmission case 1. A transmission mechanism end cover 3 that covers the end of the transmission mechanism is bolted to the flange surface on the other end side of the transmission case 1. That is, the transmission case 1, the converter cover 2, and the transmission mechanism end cover 3 constitute a unit case for the automatic transmission AT.

  The transmission input shaft 4 and the transmission output shaft 5 are disposed on the same first axis C1 and have a stepped transmission mechanism that changes the input rotation speed by hydraulic control. On the outer periphery of the transmission input shaft 4 and immediately after the torque converter 8, there are an oil pump 9 that is rotationally driven by an engine, and an oil passage plate 10 in which a pump suction passage, a pump discharge passage, and a clutch oil passage are formed. Are fixed to the transmission case 1 with bolts. The stepped transmission mechanism has a first planetary gear 11 and a second planetary gear 12 as two sets of planetary gears, and has five clutch friction elements, a first clutch 13, a second clutch 14, and a third clutch 15. And a first brake 16 and a second brake 17. Then, each of the forward fourth speed and the reverse first speed is achieved by engaging two speed change friction elements, and the fourth forward speed is achieved by changing the speed change by releasing one speed friction element and fastening one friction speed element. .

  The idler shaft 6 has an idler gear 19 that is supported by the case at a position higher than the first axis C1 and meshes with an output gear 18 provided on the transmission output shaft 5. The idler gear 19 has a parking gear 20 with an integral structure. One end of the idler shaft 6 is supported by the transmission case 1 via the first idler bearing 21, and the other end is supported by the converter cover 2 via the second idler bearing 22.

  The drive shafts 7 and 7 are case-supported at positions below the first axis C1 and the second axis C2 and mesh with an idler final gear 23 provided on the idler shaft 6 to achieve a final reduction ratio. A gear 24 is provided. Here, a differential unit having a differential case 25 for fixing the differential final gear 24 and side gears 26 and 26 for spline-fitting the drive shafts 7 and 7 between the differential final gear 24 and the drive shafts 7 and 7. Is installed. One end of the differential case 25 is supported by the transmission case 1 via the first differential bearing 27, and the other end is supported by the converter cover 2 via the second differential bearing 28.

  2 to 4 are diagrams illustrating a transmission case of the automatic transmission AT according to the first embodiment, and FIG. 5 is a cross-sectional perspective view illustrating a return flow path of the automatic transmission AT according to the first embodiment. Hereinafter, the configuration of the main part will be described with reference to FIGS.

  As shown in FIGS. 2 to 5, the automatic transmission AT according to the first embodiment includes a transmission case 1, a first axis C <b> 1, a second axis C <b> 2, a third axis C <b> 3, and an oil pan 30. A communication oil hole 31, an inner wall rib 32, a return flow path 33, an approach guide surface 34, and a rectifying unit 35.

In the transmission case 1, as shown in FIG. 2, the hydraulic oil ATF is stored in the case chamber 36, and the space above the stationary oil surface W in a stationary state is a breather space communicating with the outside air.
Here, the stationary oil level W refers to the oil level when a vehicle equipped with the automatic transmission AT is stopped on a flat road surface, which reduces the sensitivity of oil level fluctuations and secures a large volume of breather space. Therefore, it is set at a position slightly higher than the height of the first axis C1. When the vehicle is stopped or the like, the hydraulic oil ATF is stored in the case chamber 36 and the oil pan chamber 37 below the stationary oil level W.

  2 and 3, the oil pan 30 is provided by closing the lower surface opening of the control valve unit 38 set at the lower position of the transmission case 1 in an oil-tight state. Then, by closing the opening of the control valve unit 38 with the oil pan 30, an oil pan chamber 37 for storing the hydraulic oil ATF is formed. The oil pan chamber 37 has an oil strainer 40 set in the suction port 39 (see FIG. 4) of the oil pump 9. As shown in FIG. 4, the control valve unit 38 has a discharge port 41 from the oil pump 9. As shown in FIG. 2, the suction port 39 and the discharge port 41 of the oil pump 9 communicate with a pump suction passage 42 and a pump discharge passage 43 formed in the oil passage plate 10.

  As shown in FIG. 2, the communication oil hole 31 is opened at a position below the stationary oil surface W of the hydraulic oil ATF stored in the case chamber 36 in the transmission case 1, and the case chamber 36 and the oil pan chamber 37 is communicated. As shown in FIG. 2, the communication oil hole 31 is located below the intermediate portion between the first shaft center C <b> 1 and the second shaft center C <b> 2, and includes a case flange portion 44 and a rectifying extension portion 45 from the case flange portion 44. Is set in a position that is surrounded by a V shape and suppresses fluctuation of the oil level.

  As shown in FIGS. 2 and 5, the inner wall rib 32 is formed so as to protrude from the differential gear inner wall 46 along the differential final gear 24 in the transmission case 1, and is formed between the first axis C1 and the third axis C3. The case strength around the shafts of the drive shafts 7 and 7 is increased in the wall region between them. The inner wall rib 32 includes a first inner wall rib 32a, a second inner wall rib 32b, and a third inner wall rib 32c. The first inner wall rib 32a connects the bearing boss 47 of the drive shafts 7 and 7 and the mounting case portion 48 of the oil passage plate 10 provided around the axis of the first axis C1 in the radial direction. The second inner wall rib 32b connects the bearing boss 47 of the drive shafts 7 and 7 and the case flange portion 44 of the transmission case 1 in the radial direction. The third inner wall rib 32c protrudes from the bearing boss 47 of the drive shafts 7 and 7 by extending the position between the first inner wall rib 32a and the second inner wall rib 32b in the radial direction. Each connecting portion forms a smooth connecting arc surface so as to avoid stress concentration. Further, in order to increase the case strength of the region around the drive shafts 7 and 7 other than the inner wall rib 32, the outer wall rib 50 is formed so as to protrude from the differential gear outer wall 49 as shown in FIG. The outer wall rib 50 includes a first outer wall rib 50a, a second outer wall rib 50b, a third outer wall rib 50c, a fourth outer wall rib 50d, and a fifth outer wall rib 50e arranged in the horizontal direction.

  As shown in FIGS. 2 and 5, the return flow path 33 has an oil inlet 51 opened above the inner wall rib 32, and hydraulic oil ATF that has moved or scattered in the breather space is supplied from the oil inlet 51 to the oil flow inlet 51. Return to pan 30. As shown in FIG. 5, the return channel 33 has an inclined surface (for example, an inclined surface having an inclination angle of about 45 degrees) perpendicular to the line-of-sight direction when viewed obliquely from above toward the differential gear inner wall 46. The oil inlet 51 is opened. The detailed opening position of the oil inlet 51 is a position below the second axis C2 and above the inner wall rib 32. Further, as shown in FIG. 3, a return passage cross-sectional area of the return passage 33 is secured between the transmission mechanism case portion 1 a and the differential case portion 1 b of the transmission case 1.

  As shown in FIGS. 2 and 5, the approach guide surface 34 is formed on the differential gear inner wall 46 between the second axis C2 and the third axis C3, and receives the hydraulic oil ATF falling from the breather space. The hydraulic oil ATF is collected and guided to the oil inlet 51. That is, the approach guide surface 34 has a stepped surface shape with a smooth curved slope so that the hydraulic oil ATF flows with low resistance without providing a rib.

  As shown in FIG. 2, the rectifying unit 35 is formed in the transmission case 1 and includes a first rectifying surface 35a and a second rectifying surface 35b. The first rectifying surface 35 a has a shape that follows the outer shape of the differential final gear 24, and rectifies the hydraulic oil ATF that moves up and moves by the rotation of the diff final gear 24 toward the approach guide surface 34. The second rectifying surface 35 b has a shape that follows the outer shape of the idler gear 19, and rectifies the hydraulic oil ATF that moves by the rotation of the idler gear 19 toward the approach guide surface 34.

Next, the operation will be described.
First, “unit performance of the automatic transmission” will be described. Next, the operation of the automatic transmission AT according to the first embodiment will be described by dividing it into “unit required performance achievement operation”, “oil inlet inclined surface opening operation”, and “hydraulic oil level management operation”.

[Unit performance of automatic transmission]
Automatic transmission unit performance includes shaft support strength performance that maintains the support strength of the shaft supported by the case, breather performance that ensures air communication in the breather chamber, and inclined air suction that prevents air suction from the oil pump. Prevention performance is required.

  First, shaft support strength performance will be described. The final reduction ratio of the automatic transmission is achieved by meshing between an idler final gear provided on the idler shaft and a differential final gear provided on the final shaft. For this reason, at the time of starting when the first forward speed is selected, the driving torque transmitted to the final shaft is large and fluctuates. In order to suppress the case deformation and receive the reaction force with the bearing against the transmission driving torque, it is necessary to increase the support strength of the transmission case on which the bearing is supported.

  Therefore, when increasing the support strength of the drive shaft by the differential case portion surrounding the differential final gear in the transmission case, it partially overlaps with the speed change mechanism case portion, so the outer wall rib increases the support strength of the entire periphery of the final shaft. I can't. For this reason, the improvement of the support strength in the region where the outer wall rib cannot be provided must be set for the inner wall rib.

  That is, by forming the inner wall rib in the region of the differential case inner wall between the transmission shaft and the final shaft of the transmission mechanism in the differential case portion, it is possible to increase the support strength of the entire peripheral region of the final shaft. However, in this case, by forming the inner wall rib, the hydraulic oil flows into the communication hole that is located in the same region as the inner wall rib and below the stationary oil surface and communicates the case chamber and the oil pan chamber. Inhibit.

  For this reason, for example, when the hydraulic oil is scraped up by the differential final gear in a state where the oil level is greatly inclined at the time of a sudden start in which a high front and rear G is generated or a turning operation in which a high lateral G is generated, The amount of hydraulic oil that stagnate near the entrance / exit of the breather space above the surface increases. That is, the breather performance is reduced.

  Then, the amount of oil that does not return to the oil pan chamber while remaining in the breather space increases, so that the effective amount of hydraulic oil stored in the case chamber and the oil pan chamber decreases, and the oil level is lowered. As described above, when the oil level is inclined while the oil level is lowered, the oil pump sucks air from the oil strainer, and the tilted air sucking prevention performance is not ensured.

  On the other hand, if the inner wall ribs are not set, it is possible to ensure breather performance and inclined air suction prevention performance, but shaft support strength performance cannot be ensured. Of the performance, breather performance and inclined air suction prevention performance, either performance is sacrificed, or all are compromised with low performance.

[Achieving unit required performance]
As described above, in an automatic transmission, it is an important solution to achieve shaft support strength performance, breather performance, and inclined air sucking prevention performance together. Hereinafter, the effect of achieving the required unit performance in the automatic transmission AT of the first embodiment reflecting this will be described.

(Shaft support strength performance)
First, the inner wall rib 32 formed on the differential gear inner wall 46 along the differential final gear 24 and the outer wall rib 50 formed on the differential gear outer wall 49 along the differential final gear 24 are used to change the speed around the shafts of the drive shafts 7 and 7. The case strength of the machine case 1 is increased.
For this reason, the strength of the case around the first differential bearing 27 that rotatably supports the drive shafts 7 and 7 is increased, so that the support strength of the drive shafts 7 and 7 is improved.

(Breaser performance)
As shown in FIG. 5, the hydraulic oil ATF that has moved or scattered in the breather space during traveling flows in from the oil inlet 51 that is opened above the stationary oil surface W of the hydraulic oil ATF, and passes through the return flow path 33. After a while, the oil pan chamber 37 is returned.
On the other hand, of the hydraulic oil ATF that has moved or scattered in the breather space during traveling, the hydraulic oil ATF that has not flowed into the oil inlet 51 and dropped onto the oil surface of the case chamber 36 passes through the communication hole 31 thereafter. And returned to the oil pan chamber 37.
That is, when the hydraulic oil ATF flows from the oil inlet 51 located above the stationary oil surface W, the oil flow can be promptly flowed in a quicker time response than when flowing to the communication hole 31 below the stationary oil surface W. become. By increasing the amount of return oil from the return passage 33, the amount of return oil from the return passage 33 increases, the amount of oil stagnating in the breather space decreases, and the amount of scattered oil by the gear decreases. The flow is repeated.
Thus, the amount of oil stagnating in the breather space is reduced, so that the stagnation of oil at the breather inlet / outlet is eliminated and the breather function is ensured.

(Inclined air sucking prevention performance)
As described above, the flow of the action of increasing the amount of return oil from the return flow path 33 → decreasing the amount of oil trapped in the breather space → decreasing the amount of scattered oil due to the gear is repeated, so that the case chamber 36 and A decrease in the effective oil amount of the hydraulic oil ATF stored in the oil pan chamber 37 is suppressed. In other words, the oil level of the hydraulic oil ATF is managed such that the level of the static oil level W is maintained at a predetermined level. In this state where the oil level is controlled, for example, even if the oil level is inclined due to sudden start or turning, the hydraulic fluid communication between the case chamber 36 and the oil pan chamber 37 through the communication oil hole 31 is ensured. The oil pump 9 is prevented from sucking air from the oil strainer 40.

As described above, the automatic transmission AT according to the first embodiment has the inner wall rib 32 that increases the case strength around the drive shafts 7 and 7, and the oil inlet 51 that is opened above the inner wall rib 32 to the oil pan 30. The structure provided with the return flow path 33 which returns hydraulic oil ATF was employ | adopted.
Therefore, as described above, the shaft support strength performance, breather performance, and inclined air suction prevention performance, which are the required performance of the automatic transmission AT knit, are achieved.

In the first embodiment, as the inner wall rib 32, the first inner wall rib 32 a that connects the bearing boss 47 and the mounting case portion 48 of the oil passage plate 10 provided around the first axis C 1 in the radial direction, and the bearing boss 47. And the second inner wall rib 32b that connects the case flange portion 44 in the radial direction.
That is, the mounting case portion 48 and the case flange portion 44 of the oil passage plate 10 are portions of the transmission case 1 that have high rigidity. In other words, a C-shaped rib formed by the first inner wall rib 32a and the second inner wall rib 32b was formed by using a case portion having high rigidity, and this was taken as a measure against torsional strength. Specifically, the rib shape was determined by considering the analysis of static torsional stress and relaxation of stress concentration.
Therefore, the first inner wall ribs 32a and the second inner wall ribs 32b having the C-shaped arrangement improve the torsional support strength of the drive shafts 7 and 7 and suppress noise and vibration.

[Slope opening action at oil inlet]
The reason why the oil inflow port 51 into which the hydraulic oil ATF that has moved or scattered in the breather space flows will be described.
First, from the viewpoint of the oil return action, when the oil inlet 51 is installed on a horizontal plane, the amount of sucked oil increases, but the oil return hole is at a deep position during production and deburring cannot be performed. On the other hand, from the viewpoint of productivity, if the oil inlet 51 is installed on a vertical surface, the productivity is good, but the amount of sucked oil decreases.
Therefore, in the first embodiment, as shown in FIG. 5, the oil inlet 51 is opened on an inclined surface that is perpendicular to the line-of-sight direction when viewed obliquely from above toward the differential gear inner wall 46.
Therefore, productivity is ensured such that the tool can be deburred by the inserter and the edge of the opening can be rounded. In addition, by ensuring the vertical projection area of the oil inlet 51, the amount of sucked oil can be increased. That is, by ensuring that the oil inlet 51 is an opening to the inclined surface, it is possible to achieve both good productivity and increased suction oil amount.

[Oil level control action of hydraulic oil]
As described above, when the hydraulic oil ATF moves or scatters in the breather space, it is necessary to continue the flow that guides the hydraulic oil to the return flow path 33 as much as possible, and to perform oil level management that maintains the oil level. . Hereinafter, the oil level management action of the hydraulic oil ATF in Example 1 reflecting this will be described.

First, the flow of the hydraulic oil ATF caused by gear scraping will be described with reference to FIG.
Of the flow of hydraulic oil ATF caused by gear scooping, the hydraulic oil ATF that has been scraped in the clockwise direction along the differential final gear 24 by the meshing of the idler final gear 23 and the differential final gear 24 is indicated by an arrow D in FIG. As shown in the direction, the rectifying action by the first rectifying surface 35a changes the direction from upward to obliquely downward and falls.
Of the flow of hydraulic oil ATF caused by gear scooping up, the hydraulic oil ATF that has been scraped in the clockwise direction along the output gear 18 due to the meshing of the output gear 18 and the idler gear 19 is placed on the outer periphery of the idler gear 19. Along the left turn direction. Then, as shown in the direction of arrow E in FIG. 6, it falls downward by the rectifying action by the second rectifying surface 35b.
The hydraulic oil ATF dropped from both is collected and received at the end position of the approach guide surface 34, and the collected hydraulic oil ATF is smoothly moved to the right in FIG. And lead to the oil inlet 51.

  The flow of hydraulic oil ATF by acceleration / deceleration G will be described. When the high front / rear G acts during sudden start or sudden braking, or when the high lateral G acts during turning, the hydraulic oil ATF stored in the case chamber 36 reduces these acceleration / deceleration G. Receiving and moving upward toward the breather space along the inner wall surface of the case. The hydraulic oil ATF that has moved upward falls downward in accordance with gravity. Of the hydraulic oil ATF that has fallen, the hydraulic oil ATF that has fallen on the approach guide surface 34 is smooth with less resistance as described above. And flow to the oil inlet 51.

  In this way, the hydraulic oil ATF that has been lifted up by gear scooping up and the hydraulic oil ATF that has moved upward in response to acceleration / deceleration G are directly applied from the approach guide surface 34 to the oil inlet 51 or the oil inlet 51. Led. For this reason, during traveling, the flow of guiding the hydraulic oil ATF to the return flow path 33 is continued, and it is possible to perform highly accurate oil level management that suppresses the fluctuation range of the effective oil amount and maintains the oil level.

As described above, in the first embodiment, the differential oil inner wall 46 between the second shaft center C2 and the third shaft center C3 receives the hydraulic oil ATF that falls from the breather space, collects the oil, and collects the oil inflow port 51. The structure which forms the approach guide surface 34 which guides to is adopted.
Therefore, the hydraulic oil ATF that has fallen from the breather space is collected and received, and the guiding action is smoothly led to the oil inlet 51 without resistance, and the flow of guiding the hydraulic oil ATF to the return flow path 33 is continued.

In the first embodiment, the transmission case 1 is configured to include the rectifying unit 35 having the first rectifying surface 35a and the second rectifying surface 35b.
Then, the hydraulic oil ATF that is scraped and moved by the rotation of the differential final gear 24 is rectified by the first rectifying surface 35 a so as to go toward the approach guide surface 34. The hydraulic oil ATF that is moved by the rotation of the idler gear 19 is rectified by the second rectifying surface 35 b so as to be directed toward the approach guide surface 34.
Therefore, the flow of the hydraulic oil ATF caused by gear scraping is effectively rectified to guide the approach guide surface 34, and the amount of hydraulic oil ATF that flows from the oil inlet 51 and returns to the oil pan chamber 76 is secured. .

Next, the effect will be described.
In the automatic transmission AT according to the first embodiment, the effects listed below can be obtained.

(1) A transmission case 1 in which hydraulic oil ATF is stored and a space above the oil level is a breather space communicating with outside air;
A transmission shaft (transmission input shaft 4, transmission output shaft 5) having a first axis C <b> 1 that is supported by the transmission case 1 and has a transmission mechanism that changes the input rotation speed;
An idler shaft 6 having a second shaft center C2 having an idler gear 19 which is supported by the case above the first shaft center C1 and meshes with an output gear 18 provided on the transmission shaft (transmission output shaft 5). When,
Final having a third axial center C3 having a differential final gear 24 that is supported by the case at a position below the first axial center C1 and the second axial center C2 and meshes with an idler final gear 23 provided on the idler shaft 6. Shaft (drive shafts 7 and 7),
An oil pan 30 provided in the transmission case 1 for accumulating the hydraulic oil ATF and having an oil strainer 40 set in the suction port 39 of the oil pump 9;
The transmission case 1 is formed on a differential gear inner wall 46 along the differential final gear 24 in the transmission case 1, and the final shaft (drive shafts 7, 7 is formed in a wall surface region between the first axis C 1 and the third axis C 3. ) Inner wall ribs 32 for increasing the case strength around the axis;
An oil inlet 51 is opened above the inner wall rib 32, and a return passage 33 for returning the hydraulic oil ATF from the oil inlet 51 to the oil pan 30;
Is provided.
For this reason, the shaft support strength performance, breather performance, and inclined air sucking prevention performance, which are unit required performance of the automatic transmission AT, can be achieved.

(2) The return passage 33 opens the oil inlet 51 on an inclined surface perpendicular to the line-of-sight direction when viewed obliquely from above toward the differential gear inner wall 46.
For this reason, in addition to the effect of (1), by ensuring that the oil inlet 51 is an opening to the inclined surface, it is possible to achieve both good productivity and increased suction oil amount.

(3) The return flow path 33 opens the oil inlet 51 at a position below the second axis C2 and above the inner wall rib 32, and the second axis C2 and the third axis. An approach guide surface 34 that receives the hydraulic oil ATF falling from the breather space, collects the hydraulic oil ATF, and guides the hydraulic oil ATF to the oil inlet 51 is formed on the differential gear inner wall 46 between the center C3 and the center C3.
For this reason, in addition to the effect of (1) or (2), the hydraulic oil ATF that has fallen from the breather space is collected and received and smoothly guided to the oil inlet 51 without resistance. The flow leading ATF can be continued
(4) Formed in the transmission case 1 and has a shape that conforms to the outer shape of the differential final gear 24, and the hydraulic oil ATF that moves up by the rotation of the differential final gear 24 is rectified so as to be directed to the approach guide surface 34. And a second rectifying surface 35b that rectifies the hydraulic oil ATF that moves by rotation of the idler gear 19 toward the approach guide surface 34, and has a shape that conforms to the outer shape of the idler gear 19. The rectification | straightening part 35 which has is provided.
For this reason, in addition to the effect (3), the flow of the hydraulic oil ATF caused by gear scraping is effectively guided to the approach guide surface 34, and the flow is returned from the oil inlet 51 to the oil pan chamber 76. Oil amount of oil ATF can be secured.

(5) The inner wall rib 32 radially connects the bearing boss 47 of the final shaft (drive shafts 7 and 7) and the mounting case portion 48 of the oil passage plate 10 provided around the first axis C1. The first inner wall rib 32a to be connected, and the second inner wall rib 32b to connect the bearing boss 47 of the final shaft (drive shafts 7 and 7) and the case flange portion 44 of the transmission case 1 in the radial direction.
For this reason, in addition to the effects (1) to (4), the torsional support strength of the final shaft (drive shafts 7 and 7) is improved by the first inner wall rib 32a and the second inner wall rib 32b having a C-shaped arrangement. Noise and vibration can be suppressed.

(6) The transmission mechanism includes a plurality of planetary gears (first planetary gear 11 and second planetary gear 12) and a plurality of transmission friction elements (first clutch 13, second clutch 14, third clutch 15, first brake). 16, a stepped transmission mechanism that achieves a stepped shift stage (four forward speeds) by the second brake 17),
The transmission shafts are a transmission input shaft 4 and a transmission output shaft 5 arranged on the same first axis C1.
For this reason, in addition to the effects of (1) to (5), in the automatic transmission AT that has a parallel three-shaft structure and achieves a stepped gear stage, the support strength performance, breather performance, and inclination of the drive shafts 7 and 7 The air sucking prevention performance can be achieved together.

  As mentioned above, although the automatic transmission of this invention has been demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, The summary of the invention which concerns on each claim of a claim As long as they do not deviate, design changes and additions are permitted.

  In the first embodiment, the oil inlet 51 is opened at a position below the second axis C2 and above the inner wall rib 32, and the return flow path 33 is returned to the oil pan chamber 37 from the opened oil inlet 51. An example of oil holes is shown. However, the oil inlet is not limited to the opening position of the first embodiment as long as it opens to the position above the inner wall rib 32. For example, the oil flow inlet may be opened at a position corresponding to the shape of the inner wall of the case and returned to the oil pan chamber when hydraulic oil moved or scattered in the breather space.

  In Example 1, the example of the inner wall rib 32 by the 1st inner wall rib 32a and the 2nd inner wall rib 32b which become a square-shaped arrangement | positioning was shown. However, the specific shape and configuration of the inner wall rib is not limited to the first embodiment, and various shapes and configurations may be adopted according to the strength improvement request around the final axis.

  In the first embodiment, an example in which the present invention is applied to an automatic transmission AT that achieves a forward fourth speed is shown. However, the present invention can be applied to an automatic transmission that achieves a gear stage other than the fourth forward speed (for example, the fifth forward speed or more), or an automatic transmission that achieves a continuously variable transmission ratio (= continuously variable transmission). It can also be applied.

1 Transmission case 4 Transmission input shaft (transmission shaft)
5 Transmission output shaft (transmission shaft)
6 Idler shaft 7, 7 Drive shaft (final shaft)
9 Oil pump 10 Oil passage plate 11 First planetary gear (planetary gear)
12 Second planetary gear (planetary gear)
13 First clutch (shifting friction element)
14 Second clutch (shifting friction element)
15 3rd clutch (speed change friction element)
16 First brake (shifting friction element)
17 Second brake (shift friction element)
18 output gear 19 idler gear 23 idler final gear 24 differential final gear 30 oil pan 31 communicating oil hole 32 inner wall rib 32a first inner wall rib 32b second inner wall rib 33 return channel 34 approach guide surface 35 rectifying part 35a first rectification Surface 35b Second rectifying surface 36 Case chamber 37 Oil pan chamber 39 Suction port 40 Oil strainer 44 Case flange portion 46 Differential gear inner wall 47 Bearing boss 48 Mounting case portion 51 Oil inlet C1 First shaft center C2 Second shaft center C3 Third Axis
ATF Hydraulic oil W Static oil level

Claims (6)

A transmission case in which hydraulic oil is stored and a breather space communicating with outside air in a space above the oil surface;
A transmission shaft supported by the transmission case and having a first axis having a transmission mechanism for changing the input rotational speed;
An idler shaft having a second shaft center supported by a case above the first shaft center and having an idler gear meshing with an output gear provided on the transmission shaft;
A final shaft having a third axial center having a differential final gear that is supported by the case at a position below the first axial center and the second axial center and meshes with an idler final gear provided on the idler shaft;
An oil pan provided in the transmission case, storing the hydraulic oil, and having an oil strainer set at an inlet of an oil pump;
An inner wall rib that is formed on a differential gear inner wall along the differential final gear of the transmission case, and increases a case strength around the final axis in a wall surface region between the first axis and the third axis. ,
An oil inlet is opened above the inner wall rib, and a return flow path for returning the hydraulic oil from the oil inlet to the oil pan;
An automatic transmission comprising: The automatic transmission according to claim 1, wherein
The automatic transmission is characterized in that the return passage has the oil inflow opening opened on an inclined surface perpendicular to the line-of-sight direction when viewed obliquely from above toward the inner wall of the differential gear. In the automatic transmission according to claim 1 or 2,
The return flow path opens the oil inlet at a position below the second axis and above the inner wall rib, and the differential gear inner wall between the second axis and the third axis And an approach guide surface that receives the hydraulic oil falling from the breather space, collects the hydraulic oil, and guides the hydraulic oil to the oil inlet. In the automatic transmission according to claim 3,
A first rectifying surface that is formed in the transmission case and has a shape that conforms to the outer shape of the differential final gear, and that rectifies the working oil that moves up by rotation of the differential final gear toward the approach guide surface; An automatic transmission comprising: a rectifying portion having a shape that conforms to an outer shape of an idler gear, and a second rectifying surface that rectifies hydraulic oil that moves by rotation of the idler gear toward the approach guide surface. . In the automatic transmission according to any one of claims 1 to 4,
The inner wall rib includes a first inner wall rib that radially connects a bearing boss of the final shaft and a mounting case portion of an oil passage plate provided around the first axis, a bearing boss of the final shaft, and the An automatic transmission comprising: a second inner wall rib that connects a case flange portion of the transmission case in a radial direction. In the automatic transmission according to any one of claims 1 to 5,
The transmission mechanism is a stepped transmission mechanism that achieves a stepped shift stage by a plurality of planetary gears and a plurality of shift friction elements,
The automatic transmission is characterized in that the transmission shaft is a transmission input shaft and a transmission output shaft arranged on the same first axis.