阅读说明：本技术 动力传递装置 (Power transmission device ) 是由 伊藤务 杉山大 成冈聪 于 2019-01-10 设计创作，主要内容包括：无级变速器(200),具备：变速箱(1),其具有侧盖(30)、外壳(40)、以及被侧盖(30)和外壳(40)夹持的壳体(10)；油泵(180),其配置在变速箱(1)内；一对齿轮(147)、(163),其配置在变速箱(1)内。在壳体(10)内的与一对齿轮(147)、(163)相邻的位置的外壁面形成了具有从侧盖(30)向外壳(40)延伸的线性形状的轴向肋(25)。轴向肋(25)配置在从油泵(180)起沿垂直方向延伸的直线上,并且局部配置在抑制一对齿轮(147)、(163)啮合反作用力的位置。由此,能够提供在变速箱中考虑轻量化而设计的肋的结构。(A continuously variable transmission (200) is provided with: a transmission case (1) having a side cover (30), a case (40), and a case (10) sandwiched by the side cover (30) and the case (40); an oil pump (180) disposed in the transmission (1); a pair of gears (147), (163) disposed in the transmission (1). An axial rib (25) having a linear shape extending from the side cover (30) to the housing (40) is formed on the outer wall surface of the housing (10) at a position adjacent to the pair of gears (147, 163). The axial rib (25) is disposed on a straight line extending in the vertical direction from the oil pump (180) and is partially disposed at a position where the meshing reaction force of the pair of gears (147, 163) is suppressed. This makes it possible to provide a rib structure designed in consideration of weight reduction in a transmission case.)

1. A power transmission device is provided with:

a housing having a first housing member, a second housing member, and a third housing member sandwiched by the first housing member and the second housing member;

an oil pump disposed within the housing;

a pair of gears disposed within the housing,

a rib having a linear shape extending from the first case member to the second case member is formed on an outer wall surface of the third case member at a position adjacent to the pair of gears,

the rib is disposed on a straight line extending in a vertical direction from the oil pump and is locally disposed at a position where a meshing reaction force of the pair of gears is suppressed,

the rib has a shape connected to both a first connection point of the first case member and the third case member and a second connection point of the second case member and the third case member,

the uppermost surface of the rib is located at a position higher than the center point of the link hole of the first link point and the center point of the link hole of the second link point.

2. The power transmission device according to claim 1,

when the pair of gears is divided into a first region, a second region, a third region and a fourth region by an inter-axis line connecting the centers of one of the pair of gears and the other of the pair of gears and an orthogonal line passing through the center of one of the pair of gears and orthogonal to the inter-axis line,

the first region is a region located on the near side when viewed from the meshing position side of the pair of gears and located on the near side when viewed from the outer wall surface side,

the second region is a region located on a near side when viewed from a meshing position side of the pair of gears and located on a far side when viewed from the outer wall surface side,

the third region is a region located on a rear side when viewed from the meshing position side of the pair of gears and located on a near side when viewed from the outer wall surface side,

the fourth region is a region located on a back side when viewed from the meshing position side of the pair of gears and located on a back side when viewed from the outer wall surface side,

the position at which the engagement reaction force is suppressed refers to a position of the outer wall surface of the third case member adjacent to the third region.

3. The power transmission device according to claim 2,

the first connection point and the second connection point are disposed at positions on the outer wall surface of the third casing member adjacent to the third region.

4. The power transmission device according to claim 3,

the rib is a member having a hollow portion.

5. The power transmission device according to claim 4,

the hollow portion is formed of a through hole connecting the first connection point and the second connection point.

6. The power transmission device according to any one of claims 3 to 5,

the third case member includes: a support part for supporting one of the pair of gears, and a rib connected to the peripheral wall part.

Background

Patent document 1 discloses a structure in which a grid-like rib is provided over the entire outer wall surface of a transmission case.

However, if the grid-like ribs are provided over the entire outer wall surface, the weight of the transmission case increases.

Accordingly, it is necessary to provide a rib structure designed in consideration of weight reduction.

Disclosure of Invention

The power transmission device of the present invention includes:

a housing having a first housing member, a second housing member, and a third housing member sandwiched by the first housing member and the second housing member;

an oil pump disposed within the housing;

a pair of gears disposed within the housing,

a rib having a linear shape extending from the first case member to the second case member is formed on an outer wall surface of the third case member at a position adjacent to the pair of gears,

the rib is disposed on a straight line extending in a vertical direction from the oil pump and is locally disposed at a position where a meshing reaction force of the pair of gears is suppressed,

the rib has a shape connected to both a first connection point of the first case member and the third case member and a second connection point of the second case member and the third case member,

the uppermost surface of the rib is located at a position higher than the center point of the link hole of the first link point and the center point of the link hole of the second link point.

According to the present invention, a rib structure designed in consideration of weight reduction can be provided.

Drawings

Fig. 1 is a diagram for explaining a belt type continuously variable transmission.

Fig. 2 is a diagram illustrating a housing constituting a transmission case.

Fig. 3 is a perspective view of a case constituting the transmission case as viewed from the case side.

Fig. 4 is a view illustrating an axial rib provided in the housing.

Fig. 5 is a perspective view of the housing of the conventional example viewed obliquely from above.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to fig. 1 to 4, taking a case where the power transmission device is a belt type continuously variable transmission 200 for a vehicle as an example.

Fig. 1 is a diagram for explaining a belt-type continuously variable transmission 200.

Fig. 1 schematically shows a transmission path of the rotational driving force transmitted via each of the rotation transmission shafts (first shaft, second shaft, third shaft, and fourth shaft), and the transmission path extends from the torque converter 111 through the transmission mechanism 120 to the differential device 170.

Fig. 2 is a diagram illustrating the housing 10. Fig. 2(a) is a view of the case 10 as viewed from the case 40 side, and fig. 2(b) is an enlarged view of the periphery of the through hole 14a provided in the case 10. In addition, in fig. 2(a), the oil pump 180 is simply labeled.

As shown in fig. 1, the continuously variable transmission 200 is a device that continuously changes the speed of a rotational driving force output from an engine (not shown) and transmits the rotational driving force to driving wheels.

The continuously variable transmission 200 includes a torque converter 111 that inputs rotational driving force from an engine, a forward/reverse switching mechanism 112, a transmission mechanism 120, a reduction gear 161, a differential device 170, an oil pump 180, and a transmission case 1 that houses these components.

The forward/backward switching mechanism 112 includes a planetary gear mechanism, and inputs the rotational driving force output from the torque converter 111 to the speed change mechanism 120 in the clockwise rotation and the counterclockwise rotation.

The torque converter 111, the forward/reverse switching mechanism 112, and the primary pulley 130 of the transmission mechanism 120 have an axis X1 (first shaft) as a rotation center.

The secondary pulley 140 of the transmission mechanism 120 has an axis X2 (secondary shaft) as a rotation center. The reduction gear 161 has an axis X3 (third axis) as a rotation center. The differential device 170 has an axis X4 (fourth axis) as a rotation center.

The axis X1, the axis X2, the axis X3, and the axis X4 are arranged parallel to each other.

As shown in fig. 2(a), the axis X2 and the axis X3 are arranged at substantially the same height position in the vertical direction with respect to the installation state of the continuously variable transmission 200. The axis X4 is disposed substantially vertically below the axis X3. The axis X1 is substantially the same height as the axis X4 and is disposed obliquely below the axis X2.

As shown in fig. 1, the transmission mechanism 120 is a belt type cvt (continuously variable transmission). The transmission mechanism 120 includes a primary pulley 130 on an input side, a secondary pulley 140 on an output side, and a belt 151 that winds the primary pulley 130 and the secondary pulley 140 and transmits rotational driving force.

The primary pulley 130 has a fixed pulley 131 that is not displaced in the axial direction and a movable pulley 135 that is displaceable in the axial direction relative to the fixed pulley 131.

The fixed pulley 131 is rotatably supported by the housing 10 via a ball bearing 191. The output rotation of the forward/reverse switching mechanism 112 is input to the fixed pulley 131.

A V-shaped groove around which the belt 151 is wound is formed between the sheave portion 132 of the fixed sheave 131 and the sheave portion 136 of the movable sheave 135. In response to the hydraulic pressure, the groove width of the V-shaped groove changes due to displacement of the movable pulley 135 relative to the fixed pulley 131. As a result, the winding radius of the belt 151 of the primary pulley 130 changes.

Secondary pulley 140 has a fixed pulley 141 that is not displaced in the axial direction and a movable pulley 145 that is displaceable in the axial direction with respect to fixed pulley 141.

The outer case 40 side (right side of the paper surface in fig. 1) of the fixed pulley 141 is rotatably supported by the housing 10 via a roller bearing 192.

A V-shaped groove around which a belt 151 is wound is formed between sheave portion 142 of fixed sheave 141 and sheave portion 146 of movable sheave 145. In response to the hydraulic pressure, movable sheave 145 is displaced relative to fixed sheave 141, and the groove width of the V-shaped groove changes. As a result, the winding radius of the belt 151 of the second pulley 140 is changed.

That is, the power is transmitted from the primary pulley 130 to the secondary pulley 140 while the winding radius of the belt 151 of the primary pulley 130 and the winding radius of the belt 151 of the secondary pulley 140 are changed.

The gear 147 is spline-fitted to the housing 40 side of the fixed pulley 141, and the gear 147 meshes with the gear 163 on the reduction gear 161 side.

The reduction gear 161 constitutes a gear mechanism that transmits the rotation of the fixed pulley 141 to the differential device 170.

The reduction gear 161 is rotatably supported by the housing 10 via a tapered roller bearing 19 on the side of the side cover 30 (left side of the paper surface in fig. 1).

In the reduction gear 161, a gear 163 is spline fitted to the housing 40 side (right side in fig. 1).

The gear 163 meshes with the gear 147 on the secondary pulley 140 side, and the gear 147 and the gear 163 constitute a pair of gears that participate in the transmission of the rotational driving force between the secondary pulley 140 and the reduction gear 161.

When the rotational driving force is transmitted, a meshing reaction force acts on the gear 147 and the gear 163. The direction in which the meshing reaction force acts is a direction in which the gear 147 and the gear 163 are displaced in a direction away from each other (a direction of separation).

In the reduction gear 161, a gear portion 164 is provided on the side cover 30 side. The gear portion 164 meshes with a final gear 162 fixed to a differential case 171 of the differential device 170.

The differential device 170 is a device that transmits the rotational driving force transmitted via the final gear 162 to left and right drive wheels (not shown) and differentially rotates the left and right drive wheels.

The differential device 170 includes a spherical shell-shaped differential case 171, a planetary shaft 172 fixed to the differential case 171, a pair of planetary gears 173 rotating about the planetary shaft 172, and a pair of side gears 174 meshing with the planetary gears 173.

The drive shaft 310 that rotates integrally with the drive wheel is spline-fitted to the side gear 174. In fig. 1, the drive shaft 310 on the right side in the figure is not illustrated.

The differential case 171 is rotatably supported by the case 10 via a tapered roller bearing 194.

Fig. 3 is a perspective view of the housing 10 as viewed from obliquely above the side of the outer case 40.

Fig. 4 is a view for explaining the axial ribs 25 (reinforcing ribs) provided on the housing 10. Fig. 4 (a) is a perspective view showing the axial rib 25 of the housing 10 in an enlarged manner, fig. 4 (B) is a sectional view of the axial rib 25 cut along the plane a in (a), and fig. 4 (c) is a sectional view of the axial rib 25 cut along the line B-B in (B). Fig. 4 (D) is a sectional view of the axial rib 25 taken along the line C-C in (C), and fig. 4 (e) is a sectional view of the axial rib 25 taken along the line D-D in (C).

In fig. 4 (c), the outer case 40 and the side cover 30 assembled to the housing 10 are shown by imaginary lines together with the bolts 91 and 92.

As shown in fig. 1, the transmission 1 is a 3-piece case, and includes a case 10 (third case member), a side cover 30 (first case member), and a case 40 (second case member).

Specifically, the side cover 30 and the outer case 40 sandwich the housing 10 in the axial direction.

The housing 10 is a substantially cylindrical body having a thin axial direction, and houses the transmission mechanism 120 and the like therein. The housing 10 includes a substantially cylindrical outer peripheral wall 11 constituting the outer shell, and an intermediate wall 12 extending inward from the outer peripheral wall 11 and substantially separating the axial direction. The intermediate wall portion 12 is formed with a through hole 13a, a through hole 14a, a through hole 15a, and a through hole 16a that penetrate in the axial direction.

As shown in fig. 2(a), the through hole 13a is formed around the axis X1, and the intermediate wall 12 is formed with a cylindrical support wall 13 surrounding the through hole 13 a.

The support wall 13 is fitted around the ball bearing 191 (see fig. 1), and supports the ball bearing 191.

The through hole 14a is formed around the axis X2, and a cylindrical support wall 14 surrounding the through hole 14a is formed in the intermediate wall 12.

The support wall portion 14 is fitted to the roller bearing 192 (see fig. 1) and supports the roller bearing 192.

The through hole 15a is formed around the axis X3, and a cylindrical support wall 15 surrounding the through hole 15a is formed in the intermediate wall 12.

The support wall portion 15 is fitted to the tapered roller bearing 193 (see fig. 1) and supports the tapered roller bearing 193.

The through hole 16a is formed around the axis X4, and the intermediate wall 12 is formed with a cylindrical support wall 16 surrounding the through hole 16 a.

The support wall portion 15 is fitted to the tapered roller bearing 194 (see fig. 1) and supports the tapered roller bearing 194.

As shown in fig. 1, a surface of the case 10 on the side cover 30 side is provided with a joint portion 21 with the side cover 30. The engagement portion 21 is formed in a ring shape surrounding the transmission mechanism 120 when viewed from the side cover 30 side, and the transmission mechanism 120 is housed inside the ring-shaped engagement portion 21.

A bolt hole 21a (first connection point) is formed in the joint portion 21. A plurality of bolt holes 21a are provided with a gap therebetween in the circumferential direction, and bolts 91 penetrating the peripheral edge portion 35 of the side cover 30 are screwed into the respective bolt holes 21 a.

The side cover 30 fixed to the joint portion 21 by the bolt 91 seals the opening of the annular joint portion 21.

As shown in fig. 2, a surface of the case 10 on the side of the case 40 is provided with a joint portion 22 with the case 40. The joint portion 22 is formed in a ring shape as viewed from the housing 40 side, and a bolt hole 22a (second connection point) is formed in the joint portion 22. Bolts 92 (see fig. 1) penetrating the peripheral edge 45 of the housing 40 are screwed into the respective bolt holes 21 a.

A torque converter 111 (see fig. 1) is housed inside the case 40 fixed to the joint portion 22 by the bolt 92.

As shown in fig. 2, an oil pump 180 is provided between the through hole 13a and the through hole 16a and below the through holes 13a and 16a inside the annular coupling portion 22 as viewed from the housing 40 side.

In the housing 10, the oil pump 180 is disposed in proximity to a region located below the joint portion 22 in a vertical direction (vertical direction in fig. 2 (a)) with respect to the installation state of the continuously variable transmission 200.

The oil pump 180 is a mechanical oil pump driven by the rotational driving force of an engine (not shown). The rotational driving force of the engine is input to the oil pump 180 via a chain (not shown) of a driving force transmission mechanism (not shown). The oil pump 180 is driven by the input rotational driving force, sucks and pressurizes oil in an oil pan (not shown) fixed to a lower portion of the casing 10, and supplies hydraulic pressure for the operation of the continuously variable transmission 200 to a hydraulic control circuit (not shown).

The oil pump 180 is one of the sources of vibration and sound vibration of the continuously variable transmission 200.

Therefore, as shown in fig. 5, in the conventional case 10A, a strength rib 420 for securing strength against vibration and a sound vibration rib 410 for suppressing sound vibration are provided on the outer peripheral wall portion 11 of the case 10A.

These strength ribs 420 and the sound vibration ribs 410 are formed as solid plate-like or band-like portions in the middle, and are formed integrally with the case 10A when the case 10A is cast.

In the case 10A, these strength ribs 420 and the sound vibration rib 410 are formed independently of each other.

In contrast, as shown in fig. 3 and 4 (a), in the case 10 of the present embodiment, the axial ribs 25 having the function of the strength rib and the function of the sound vibration rib are provided together with the conventional strength rib 420.

As with the strength rib 420, the axial rib 25 is formed integrally with the housing 10 by bulging outward from the surface of the outer peripheral wall portion 11 of the housing 10 toward the outside of the housing 10.

The arrangement of the axial ribs 25 in the housing 10 and the structure of the axial ribs 25 will be described below.

As shown in fig. 2a, in the housing 10, the oil pump 180 is located below the through hole 14a in a vertical direction (vertical direction in fig. 2a) with reference to the installation state of the continuously variable transmission 200.

The oil pump 180 is located on a vertical line VL passing through the center (axis X2) of the through hole 14a, and the support wall portion 14 surrounding the through hole 14a is located above the oil pump 180.

As shown in fig. 1, the fixed pulley 141 of the secondary pulley 140 is rotatably supported by the support wall portion 14. The reduction gear 161 is rotatably supported by the support wall portion 15 adjacent to the support wall portion 14.

As described above, the gear 163 on the reduction gear 161 side and the gear 147 on the secondary pulley 140 side are rotatably and transmissively engaged.

When rotation is transmitted between the reduction gear 161 and the secondary pulley 140, meshing reaction forces in directions away from each other (directions of separation) act on the gear 147 and the gear 163.

Stress corresponding to the meshing reaction force of the gear 163 and the gear 147 acts on the support wall portions 14 and 15. Therefore, in the case 10, stress corresponding to the engagement reaction force acts on the region around the support wall portion 14 and the region around the support wall portion 15 (see fig. 2 (b)).

Here, the region around the support wall portion 14 in the housing 10 is divided into a first region, a second region, a third region, and a fourth region, and defines the direction in which the stress corresponding to the engagement reaction force acts.

As shown in fig. 2a and 2 b, the first, second, third, and fourth regions are defined by a line segment L1 connecting the center (axis X2) of one gear 147 and the center (axis X3) of the other gear 163, and a line segment L2 passing through the center (axis X2) of one gear 147 of the pair of gears and orthogonal to the line segment L1.

According to the results of stress analysis by experiments and simulations, the first region and the third region are larger than the second region and the fourth region due to the influence of the meshing reaction force. The first region and the third region are two regions located on the joint 22 side with respect to the line segment L1.

Further, the region (third region) around the support wall portion 14 is larger than the region (first region) around the support wall portion 15, in terms of the influence of the engagement reaction force.

Therefore, the housing 10 has a plurality of radial ribs 26 connected to the outer periphery of a region (upper region in the figure) facing the joint portion 22 of the support wall portion 14.

The radial ribs 26 are provided across the support wall portion 14 and the engagement portion 22, and the radial ribs 26 are provided in plurality at intervals in the circumferential direction around the axis X2.

Therefore, the rigidity strength around the support wall portion 14 of the case 10 is improved by these plural directional ribs 26.

Further, in the case 10, the outer peripheral wall portion 11 located on the upper side as viewed from the oil pump 180 in the vertical line direction with reference to the installation state of the continuously variable transmission 200 acts on the influence of the engagement reaction force and the influence of the acoustic vibration in the region corresponding to the third region (see the hatched region in fig. 2 (b)).

Therefore, the housing 10 is provided with an axial rib 25 for improving the rigidity strength on the outer periphery of the outer peripheral wall portion 11 and the region corresponding to the third region.

As shown in fig. 3, an axial rib 25 is provided on the outer side surface of the outer peripheral wall portion 11 at a position substantially above the support wall portion 14. The position where the axial rib 25 is provided is a position where the meshing reaction force of the gear 147 and the gear 163 (a pair of gears) is suppressed.

The axial ribs 25 are linearly arranged in an orientation along the axis X2 as viewed in a radial direction of the axis X2 passing through the center of the support wall portion 14.

The axial ribs 25 are provided to cross the outer peripheral wall portion 11 from one side of the case shell 40 to the other side of the side cover 30 when viewed in the radial direction of the axis X2.

The axial ribs 25 are provided across the bolt holes 22a of the joint portion 22 provided on the case 40 side and the bolt holes 21a of the joint portion 21 provided on the side case 30 side (see fig. 4).

Communication holes 25a (hollow portions) that communicate the bolt holes 21a (first connection points) and the bolt holes 22a (second connection points) are formed in the axial rib 25. The communication hole 25a is formed along a center line Cx connecting the center point of the bolt hole 21a and the center point of the bolt hole 22 a.

The axial rib 25 is formed in a shape connecting both the bolt hole 21a and the bolt hole 22a, and the outer peripheral surface 251 (uppermost surface) of the axial rib 25 is located at a position higher than the center line Cx (a position distant from the surface of the outer peripheral wall portion 11 of the transmission case 1) (see fig. 4 (d) and (e)).

As shown in fig. 2, in the region (third region) where the meshing reaction force acts, the axial rib 25 is provided in a positional relationship overlapping with the radial rib 26 in the circumferential direction around the axis X2 as viewed from the direction of the axis X2.

Therefore, the axial rib 25 and the radial rib 26 are located on a line segment R indicating the position of the same phase as viewed from the direction of the axis X2.

In the case 10, the axial ribs 25 and the radial ribs 26 form one rib that is continuous while being bent, and the rigidity strength around the support wall portion 14 in the case 10 is further improved by the complementary effect of these axial ribs 25 and radial ribs 26.

Here, the region of the outer peripheral wall portion 11 of the housing 10 corresponding to the third region is located above the oil pump 180, and is a position affected by the sound vibration of the oil pump 180 as described above.

In the case 10A of the conventional example, only the middle sound vibration rib 410 is provided in this region, but in the present embodiment, the axial rib 25 is provided with a hollow portion by providing a hollow portion in the axial rib 25, so that the axial rib 25 has the function of a strength rib and the function of a sound vibration rib.

Specifically, as shown in fig. 4, communication holes 25a (hollow portions) that communicate the bolt holes 21a and 22a are formed in the axial rib 25.

The hollow portion suppresses propagation of acoustic vibration, suppressing release of acoustic vibration to the outside of the housing 10.

Further, in the case 10, the bolt holes 21a, the bolt holes 22a, and the communication holes 25a are positioned so that the bolt holes 21a of the joint portions 21 on the side covers 30, the bolt holes 22a of the joint portions 22 on the side shells 40, and the communication holes 25a in the axial ribs 25 are connected in series.

Therefore, when the side cover 30 and the outer case 40 are fixed to the housing 10 with the bolts 91, 92, the coupling pressure of the bolts 91, 92 acts on the portions of the axial ribs 25. Thereby, the rigidity strength of the hollow axial rib 25 is ensured.

Fig. 5 is a diagram illustrating a conventional case 10A. Fig. 5 (a) is a perspective view of the housing 10A viewed from obliquely above, (b) is an enlarged view of a main portion of (a), and (c) is a view schematically showing the periphery of the rib 410 shown in (b) cut by the surface a.

Here, the difference between the axial rib 25 of fig. 4 (hereinafter simply referred to as rib 25) and the rib 410 of fig. 5 will be described in detail.

The rib 410 of fig. 5 is a sound vibration rib, and has only to have a function of dividing a flat drum-shaped surface, and is thin and flat in order to save materials (cost and weight).

On the other hand, the rib 25 of fig. 4 requires a function of a strength rib in addition to the function of the sound vibration rib.

In order to improve the function as a strength rib, it is effective to increase the longitudinal section coefficient by thickening the shape in the longitudinal direction.

Therefore, the uppermost surface (outer peripheral surface 410a) of the rib 410 of fig. 5 is at least thin and positioned lower than the center line Cx passing through the center point of the coupling hole (bolt hole 23 a).

In contrast, the rib 25 of fig. 4 has a thick top surface (outer peripheral surface 251) at least at a position higher than the center line Cx connecting the center points of the connecting holes (bolt holes 21a and 22a), and thus has a function of a strength rib in addition to a function of a sound vibration rib.

In fig. 4, in order to further enhance the function as a strength rib, the uppermost surface (outer circumferential surface 251) of the rib 25 of fig. 4 is disposed at a position higher than the uppermost point Px of the coupling holes (bolt holes 21a, 22a) at a position higher than the center point of the coupling holes (center line Cx of the center points of the coupling bolt holes 21a, 22 a).

In addition, the material used for 1 rib increases as the rib becomes thicker, but the material can be reduced as a whole because the strength rib elsewhere can be eliminated.

Further, the rib 25 of fig. 4 functioning as a sound-vibration rib and a strength rib is connected from the first connection point (bolt hole 21a) to the second connection point (bolt hole 22a) at an extremely short distance (preferably, the shortest distance), and the rib is disposed at a position where the meshing reaction force of the pair of gears is suppressed, and in fig. 4, the positions of the connection points are shifted from fig. 5, and the positions of the connection points are disposed at the positions of the outer wall of the third case member (case 10) adjacent to the third region.

Further, by connecting from the first connecting point to the second connecting point at an extremely short distance (preferably, the shortest distance), the material used can be saved.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(1) The continuously variable transmission 200 has:

a case (transmission case 1) having a first case member (side cover 30), a second case member (case 40), and a third case member (case 10) sandwiched by the first case member and the second case member;

an oil pump 180 disposed in the housing 10;

a pair of gears (gear 147, gear 163) disposed in the housing 10.

An axial rib 25 (rib) having a linear shape extending from the side cover 30 to the housing 40 is formed on the outer peripheral wall portion 11 (outer wall surface) of the case 10 at a position adjacent to the pair of gears (gear 147, gear 163).

The axial rib 25 is disposed in a region on a straight line VL extending in the vertical direction from the oil pump 180, and is partially disposed at a position where a reaction force of meshing of the pair of gears (the gear 147 and the gear 163) is suppressed.

The axial rib 25 has a shape that is connected to both a first connection point (bolt hole 21a) of the first case member (side cover 30) and the third case member (case 10) and a second connection point (bolt hole 22a) of the second case member (case 40) and the third case member (case 10).

The outer peripheral surface 251 (uppermost surface) of the axial rib 25 is located at a position higher than the center line Cx (position of the surface of the transmission case 1 away from the outer peripheral wall portion 11).

In this configuration, by partially disposing the axial ribs 25 at necessary positions, it is possible to form non-grid-like ribs which need not be provided over the entire outer wall surface of the housing 10. Therefore, the weight increase due to the addition of the rib can be suppressed, and the weight can be reduced.

Further, since the local axial ribs 25 have the sound vibration suppressing function and the strength improving function, as shown in fig. 5 (a) and 5 (b), the number of ribs can be reduced as compared with the case where the sound vibration suppressing ribs 410 and the strength improving ribs 420 are provided separately. This makes the weight of the apparatus lighter.

That is, in the region of the case 10 directly above the oil pump 180, since radiation sound such as oil pump noise is generated, in order to suppress vibration caused by the radiation sound, the case 10 (third case) is formed in a shape (linear shape extending from the side cover 30 to the case 40) in which a flat area of the outer wall surface of the case 10 is divided on a straight line extending in the vertical direction from the oil pump 180, and therefore, has a sound vibration suppression function.

Further, although a reaction force is generated by the engagement of the pair of gears (gear 147, gear 163), since the axial rib 25 is provided at a position where the reaction force is pressed, it is possible to provide a strength-improving function.

In this way, by forming the axial ribs 25 locally at the positions that also serve as the acoustic vibration and the strength, the weight increase due to the addition of the ribs can be suppressed.

Here, the connection points (first connection points, second connection points) are positions (points) at which the case 10, the side cover 30, and the housing 40 are connected by joining connecting members (screws, bolts, etc.) to each other.

With the above-described configuration, when the axial rib 25 is connected to the two connection points (the bolt hole 21a and the bolt hole 22a), one end of the axial rib 25 is fixed to one of the connection points (the bolt hole 21a), and the other end of the axial rib 25 is fixed to the other connection point (the bolt hole 22 a). This can improve the strength improving function of the axial rib 25.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(2) The region around the pair of gears (gear 147, gear 163) in the housing 10 is divided into a first region, a second region, a third region, and a fourth region, and when defining the position where the meshing reaction force is suppressed, the position where the meshing reaction force is suppressed is the position of the outer peripheral wall portion 11 (outer wall surface) of the housing 10 adjacent to the third region.

As shown in fig. 2a and 2 b, the first, second, third, and fourth regions are defined by a line segment L1 connecting the center (axis X2) of one (gear 147) of the pair of gears and the center (axis X3) of the other (gear 163), and a line segment L2 passing through the center (axis X2) of one (gear 147) of the pair of gears and perpendicular to the line segment L1.

The first region is a region located on the near side (power output side) when viewed from the meshing position side of the pair of gears (gear 147, gear 163), and located on the near side (side close to outer peripheral wall portion 11) when viewed from the outer wall side (outer peripheral wall portion 11 side).

The second region is a region located on the near side (power output side) when viewed from the meshing position side of the pair of gears (gear 147, gear 163), and located on the far side (side away from outer peripheral wall 11) when viewed from the outer wall side (outer peripheral wall 11).

The third region is a region located on the far side (power input side) when viewed from the meshing position side of the pair of gears (gear 147, gear 163), and located on the near side (side close to outer peripheral wall 11) when viewed from the outer wall surface side (outer peripheral wall 11).

The fourth region is a region located on the back side (power input side) when viewed from the meshing position side of the pair of gears (gear 147, gear 163), and located on the back side (side away from outer peripheral wall 11) when viewed from the outer side wall (outer peripheral wall 11).

With this configuration, the axial rib 25 is partially disposed in the third region, which is a position where the meshing reaction force is suppressed.

This can prevent the weight of the case 10 from increasing, and can secure the rigidity strength around the outer peripheral wall portion 11 of the case 10 and suppress radiation sound due to sound vibration.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(3) The first connection point and the second connection point are disposed at the position of the outer peripheral wall portion 11 (outer wall surface) of the case 10 (third case member) adjacent to the region (third region) where the engagement reaction force acts.

With this configuration, the axial rib 25 and the radial rib 26 connected to both the first connection point (bolt hole 21a) and the second connection point (bolt hole 22a) are provided in a positional relationship in which they overlap in phase in the circumferential direction around the axis X2.

In this way, the axial ribs 25 and the radial ribs 26 form one continuous rib while being bent in the case 10, and the stiffness strength around the support wall portion 14 of the case 10 is further improved by the complementary effect of the axial ribs 25 and the radial ribs 26.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(4) The axial rib 25 has a hollow portion (communication hole 25 a).

When configured in this way, by providing the axial rib 25 with a hollow portion where the metal itself of the coupling member or the housing is absent, the sound vibration suppressing effect can be enhanced by the influence of the hollow portion. This is based on the effect that sound is difficult to transmit due to the presence of an air layer.

As a method for producing the hollow portion, for example, a method for producing a hollow portion by slightly digging a bolt hole (screw hole) deep, or a method for producing a hollow portion penetrating through two bolt holes may be used. The method of manufacturing the hollow portion is not limited to this method.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(5) The hollow portion (communication hole 25a) is constituted by a through hole that connects the first connection point (bolt hole 21a) and the second connection point (bolt hole 22 a).

In such a configuration, the volume of the hollow portion, that is, the volume of the air layer, is increased by the penetration, and therefore, the sound vibration suppression effect is improved.

The continuously variable transmission 200 of the present embodiment has the following configuration.

(6) The third case member (case 10) has a support portion (support wall portion 14) that supports one (gear 147) of the pair of gears, and a radial rib 26 that connects the peripheral wall portion (outer peripheral wall portion 11) thereof.

With this configuration, the support wall portion 14 is easily positioned with respect to the outer peripheral wall portion 11 because the radial ribs 26 connect the support wall portion 14 and the outer peripheral wall portion 11. This increases the rigidity of the support wall 14, and therefore, the gear 147 can be supported satisfactorily.

In the above embodiment, the case where the driving force transmission device is an automatic transmission for a vehicle is exemplified. The driving force transmission device of the present invention is not limited to the automatic transmission for a vehicle.

The present invention can also be applied to a gear train including a plurality of gears, and an apparatus including at least one gear capable of splashing oil in a storage tank of the gear train. As such a device, a reduction device that reduces the speed of input rotation and outputs the rotation is exemplified.

The embodiments of the present invention have been described above, but the present invention is not limited to the embodiments described above. The present invention can be modified as appropriate within the scope of the technical idea of the present invention.