Oil circulation structure

Abstract

To provide an oil circulation structure of a transmission which can inhibit circulation of an oil mixed with air to adjust a circulation flow rate of the oil to a proper level.SOLUTION: An oil circulation structure 1B includes: a case 3 which houses a transmission unit 2A of a transmission 2; an oil pan 35 disposed at the lower side of the case 3; and a strainer 36 disposed at the oil pan 35. The strainer 36 has a suction port 37 for suctioning an oil stored in the oil pan 35. The case 3 has outflow holes 3B which are open to enable the oil to flow toward the oil pan 35. A partition part 50 is provided between the suction port 37 and the outflow holes 3B. The partition part 50 forms a detour path 51 which causes the oil flowing out from the outflow holes 3B to detour and guides the oil to the suction port 37. A magnet member 52 is provided on a path of the detour path 51.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an oil circulation structure for a transmission. [Background technology]

[0002] Conventionally, CVTs (Continuously Variable Transmissions) have been used as transmissions for various vehicles (see, for example, Patent Document 1). The CVT described in Patent Document 1 above has a primary pulley to which power from a drive source such as an engine is input, a secondary pulley that outputs the power after speed change, and an endless steel belt that is stretched over the primary and secondary pulleys. The primary pulley, secondary pulley, and steel belt are housed in a transmission case as a transmission unit (transmission mechanism). An oil pan is provided at the bottom of the CVT described in Patent Document 1 above, and the oil pan stores oil as hydraulic oil and lubricating oil.

[0003] A strainer for filtering the oil is provided below the CVT described in Patent Document 1. The oil passes through the valve body and is used for operating and lubricating the primary pulley, secondary pulley, steel belt, etc., before being returned to the oil pan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-25553 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the oil in the CVT described in Patent Document 1 is struck by the belts and pulleys and agitated by their rotation. This causes air to mix with the oil, generating bubbles and resulting in oil with a high air bubble content (e.g., cloudy oil). As a result, at least a portion of the oil with a high air bubble content is returned to the oil pan. The oil returned to the oil pan is sucked up through the suction port of the strainer and filtered. The oil filtered by the strainer is then supplied to each component of the transmission unit via the valve body.

[0006] In the CVT described in Patent Document 1, the strainer's intake port is located opposite the center of the oil pan. Therefore, the oil with a high porosity flows down near the strainer's intake port. As a result, the oil with a high porosity is sucked in through the strainer's intake port and supplied to various components.

[0007] However, oil with a high air bubble content has properties such as viscosity that differ from what should be achieved, which can cause hydraulic abnormalities. As a result, there is a concern that the CVT described in Patent Document 1 may experience poor shifting. There is also a concern that abnormal noise may be generated when the air bubbles are crushed by the oil pump.

[0008] Furthermore, the oil pump in a CVT is generally driven by engine power. For example, when the engine is in low rotation, such as in neutral range (N) or parking range (P), the pump speed decreases, reducing the oil circulation flow rate. As a result, oil with a high air bubble content accumulates and collects around the strainer's intake port, and the collected air bubbles are intermittently sucked up by the oil pump. This raises concerns about abnormal noise and reduced oil pressure in conventional CVTs. Furthermore, the supply of oil with a high air bubble content raises concerns about the increased likelihood of oil supply shortages.

[0009] Therefore, an object of the present invention is to provide an oil circulation structure for a transmission that can optimize the circulating flow rate of oil by suppressing the circulation of oil containing air. [Means for solving the problem]

[0010] (1) The oil circulation structure of the present invention, which is provided to solve the above-mentioned problems, is an oil circulation structure for a transmission mounted on a vehicle, and comprises a case that houses a gear change unit in the transmission, an oil pan arranged below the case, and a strainer arranged in the oil pan, wherein the strainer has an intake port that sucks up oil stored in the oil pan, and the case has an outlet hole that opens toward the oil pan to allow the oil to flow out, and a partition is provided between the intake port and the outlet hole, and the partition forms a detour that diverts the oil flowing out from the outlet hole and leads it to the intake port.

[0011] The oil circulation structure described above includes a partition between an outlet hole opened in a case housing the transmission unit and an inlet port of the strainer, and the partition forms a detour path that diverts oil flowing out of the outlet hole and leads it to the inlet port. Therefore, air bubbles are separated from oil with a high air bubble content flowing out of the outlet hole as it passes through the detour path. This allows the oil circulation structure described above to circulate oil with a low air bubble content, thereby maintaining an appropriate oil pressure and preventing gear shifting problems in the transmission. Furthermore, the oil circulation structure described above can reduce the air bubble content of the oil drawn into the inlet port of the strainer, thereby suppressing noise generated by the oil pump when drawing up oil.

[0012] In a transmission to which the above-described oil circulation structure is applied, iron particles and the like may become mixed into the oil due to wear or burrs on the various parts (e.g., gears, pulleys, steel belts, etc.) to which the oil is supplied. If oil containing such iron particles is supplied to the various parts, there is a concern that the hydraulic circuit in the valve body may become clogged or the iron particles may get caught in the various parts. As a result, there is a concern that the transmission may not shift properly or that the transmission itself may be damaged.

[0013] (2) To solve this problem, the oil circulation structure of the present invention may include a magnet member disposed on the route of the bypass passage.

[0014] The above-described oil circulation structure, by being configured in this manner, can effectively remove iron particles mixed in the oil. As a result, the above-described oil circulation structure can remove iron particles from the oil supplied to the transmission (gear change unit), thereby suppressing transmission shifting problems and damage caused by foreign matter getting caught in the oil. Here, the magnet member is preferably formed as a drain bolt for the oil pan. By being configured in this manner, the above-described oil circulation structure can easily discharge metal particles attracted to the magnet member, for example, when changing oil. Furthermore, by forming the magnet member as a drain bolt, the installation space for the magnet member can be consolidated, which is expected to lead to a more compact transmission.

[0015] However, when a vehicle is driven on a rough road (a road with many bumps), there is a concern that the oil pan of the transmission may come into contact with stones or protrusions on the road, causing the oil pan to deform. Furthermore, if the oil pan is deformed, oil may not be supplied normally, which could cause the transmission to become inoperable.

[0016] (3) Therefore, in order to solve such problems, in the oil circulation structure of the present invention described above, a valve body that forms a hydraulic circuit is arranged above the oil pan, and the partition portion is preferably formed from the lower end side of the valve body to the bottom of the oil pan.

[0017] The above-described oil circulation structure, by being configured as described above, can suppress deformation of the oil pan, for example, when the bottom of the oil pan receives an impact. That is, in the above-described oil circulation structure, when the bottom of the oil pan receives an impact, the partition portion braces between the bottom of the oil pan and the valve body. This allows the above-described oil circulation structure to operate stably. Furthermore, it is expected that an oil pan protector for suppressing deformation of the oil pan can be simplified or eliminated, which is expected to contribute to reducing the weight of the vehicle.

[0018] (4) In the oil circulation structure of the present invention described above, the speed change unit may include a primary pulley that is rotationally driven in response to input of power from a drive source, a secondary pulley that outputs the power after speed change, and an endless belt that is stretched across the primary pulley and the secondary pulley.

[0019] The above-described oil circulation structure can be adapted for use in continuously variable transmissions (CVTs) by virtue of its configuration. This allows the above-described oil circulation structure to prevent oil containing a large amount of air (oil with a high void content) from being sucked into the strainer's suction port. As a result, the above-described oil circulation structure can prevent oil with a high void content from circulating, thereby preventing poor shifting and abnormal noise. [Effects of the Invention]

[0020] The present invention can provide an oil circulation structure for a transmission that can optimize the oil circulation flow rate by suppressing the circulation of oil containing air. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view of a continuously variable transmission employing an oil circulation structure of the present invention, as viewed from above; [Figure 2] 1 is a partially cutaway perspective view of a continuously variable transmission employing an oil circulation structure of the present invention, as viewed from the rear side; [Figure 3]FIG. 2 is a bottom view of the oil circulation structure of the present invention with the oil pan removed. [Figure 4] FIG. 3 is a cross-sectional view taken along the arrow AA in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0022] An oil circulation structure 1 according to an embodiment of the present invention will be described below with reference to Figs. 1 to 4. In this embodiment, the oil circulation structure 1 of the present invention will be described as being applied to a continuously variable transmission (CVT) 2 as a transmission 2. The continuously variable transmission 2 will be described as being connected to an engine (not shown) as a drive source. Note that oil is omitted from the drawings.

[0023] In describing the oil circulation structure 1, first, the continuously variable transmission 2 that constitutes a part of the oil circulation structure 1 will be described in detail below.

[0024] Fig. 1 is a cross-sectional view of the continuously variable transmission 2 as seen from above. Fig. 2 is a perspective view of the case 3 of the continuously variable transmission 2, with a portion cut away, as seen from the rear side of the vehicle. Fig. 3 is a bottom view of the continuously variable transmission 2 as seen from the bottom side with the oil pan 35 removed. Note that the primary shaft 10 is omitted from Fig. 2.

[0025] The continuously variable transmission 2 is mounted on a vehicle (not shown) and is configured to change the speed of power from an engine (not shown) and output the power. As shown in Fig. 1, the continuously variable transmission 2 includes a case 3 forming an outer shell, a primary shaft 10, a primary pulley 15 supported on the primary shaft 10, a secondary shaft 20 provided parallel to the primary shaft 10, a secondary pulley 25 supported on the secondary shaft 20, and a steel belt 30 (also referred to as endless belt 30) stretched around the primary pulley 15 and the secondary pulley 25. In addition to the above, the continuously variable transmission 2 also includes an oil pan 35, a strainer 36 (see Fig. 3), a valve body 60, and the like, all of which are shown in Fig. 4. In this embodiment, the continuously variable transmission 2 is a longitudinally mounted CVT arranged along the fore-and-aft direction of the vehicle.

[0026] As shown in Figures 1 and 2, the case 3 is formed as a main body frame of the continuously variable transmission 2, and is formed in a cylindrical shape so as to be able to integrally house therein a transmission unit 2A (transmission mechanism 2A) such as the primary shaft 10, primary pulley 15, secondary shaft 20, secondary pulley 25, and steel belt 30. The case 3 also has a bottom wall 3A (see Figure 2) below the primary pulley 15 and secondary pulley 25. Details of the bottom wall 3A will be described later. The case 3 can also store some of the oil (also called lubricating oil, including fluid) inside.

[0027] The primary shaft 10 (see FIG. 1) is connected to an input shaft (not shown) that transmits the power output from the engine via an appropriate clutch (not shown) or the like. Therefore, the power output from the engine is input to the primary shaft 10. The primary shaft 10 is disposed so that its axis is located at the lower right when viewed from the rear of the vehicle. Therefore, the primary shaft 10 is disposed offset downward in the vertical direction with respect to the secondary shaft 20, which will be described later.

[0028] As shown in Fig. 1, the primary pulley 15 includes a primary moving sheave 16 on the moving side and a primary fixed sheave 17 on the fixed side. The primary moving sheave 16 and the primary fixed sheave 17 are arranged to face each other with a steel belt 30 interposed therebetween. In this embodiment, the primary moving sheave 16 is arranged on the front side of the vehicle (the rear side in the figure), and the primary fixed sheave 17 is arranged on the rear side of the vehicle (the near side in the figure). Furthermore, the opposing surfaces of the primary moving sheave 16 and the primary fixed sheave are formed in a conical shape.

[0029] Primary moving sheave 16 is rotatably supported on primary shaft 10 and can rotate integrally with primary shaft 10. In this embodiment, primary pulley 15 is set to rotate in the direction of the arrow shown in FIG. 2 (clockwise when viewed from the rear of the vehicle). Therefore, primary shaft 10 is rotationally driven in response to the input of power from the engine, and thus primary pulley 15 is rotationally driven. Furthermore, primary moving sheave 16 can be moved in the axial direction of primary shaft 10 by primary piston 18.

[0030] Furthermore, the primary piston 18 can move the primary moving sheave 16 toward or away from the primary fixed sheave 17. A steel belt 30 is arranged between the primary moving sheave 16 and the primary fixed sheave, and by driving the primary moving sheave 16 toward the primary fixed sheave 17, the steel belt 30 is sandwiched and held between the primary moving sheave 16 and the primary fixed sheave. As a result, power input to the primary shaft 10 is transmitted to the steel belt 30.

[0031] Secondary shaft 20 is disposed parallel to primary shaft 10 and offset upward relative to primary shaft 10 (see FIG. 2). That is, primary pulley 15 and secondary pulley 25 are disposed such that their respective axes (primary shaft 10 and secondary shaft 20) are offset to one side (upper side) and the other side (lower side) in the vertical direction.

[0032] The secondary pulley 25 includes a secondary moving sheave 26 on the moving side and a secondary fixed sheave 27 on the fixed side. The secondary moving sheave 26 and the secondary fixed sheave 27 are arranged to face each other with a steel belt 30 interposed therebetween. In this embodiment, the secondary fixed sheave 27 is arranged on the front side of the vehicle (the rear side in the figure), and the secondary moving sheave 26 is arranged on the rear side of the vehicle (the near side in the figure). In other words, the secondary moving sheave 26 and the secondary fixed sheave 27 are arranged so that the front and rear are reversed to the primary moving sheave 16 and the primary fixed sheave 17. Furthermore, the opposing surfaces of the secondary moving sheave 26 and the secondary fixed sheave 27 are formed in a conical shape.

[0033] The secondary moving sheave 26 is rotatably supported on the secondary shaft 20 and can rotate integrally with the secondary shaft 20. In this embodiment, the secondary pulley 25 is set to rotate in the direction of the arrow shown in FIG. 2 (clockwise when viewed from the rear of the vehicle). Therefore, the primary pulley 15 is driven to rotate, and accordingly, the secondary pulley 25 is driven to rotate. In addition, the secondary moving sheave 26 can be moved in the axial direction of the secondary shaft 20 by a secondary piston 28.

[0034] In addition, the secondary piston 28 can move the secondary moving sheave 26 toward or away from the secondary fixed sheave 27. A steel belt 30 is arranged between the secondary moving sheave 26 and the secondary fixed sheave 27, and by driving the secondary moving sheave 26 toward the secondary fixed sheave 27, the steel belt 30 is sandwiched and held between the secondary moving sheave 26 and the secondary fixed sheave 27. As a result, power input to the primary shaft 10 is transmitted to the secondary pulley 25 via the steel belt 30.

[0035] The steel belt 30 is formed, for example, by supporting a number of steel links on an endless steel ring. The steel belt 30 is wound around the primary pulley 15 and the secondary pulley 25. In the continuously variable transmission 2, the gear ratio (pulley ratio of the primary pulley 15 and the secondary pulley 25) is changed continuously and infinitely within a predetermined gear ratio range by changing the groove width of each of the primary pulley 15 and the secondary pulley 25. In other words, the power input to the input shaft is changed in speed by the continuously variable transmission 2, and the changed power is output from the secondary shaft 20.

[0036] 4, the oil pan 35 is disposed in a region on the lower end side of the continuously variable transmission 2. The oil pan 35 can store oil (also called fluid) filled as hydraulic oil and lubricating oil for the continuously variable transmission 2. The oil pan 35 is attached to the case 3 in a liquid-tight manner using an appropriate seal (not shown).

[0037] As shown in FIG. 3, the strainer 36 is disposed within the oil pan 35. The strainer 36 has an inlet 37 that draws oil from the oil pan 35. The inlet 37 opens downward. The inlet 37 can draw oil from the oil pan 35 using hydraulic pressure generated by driving the oil pump. The strainer 36 incorporates a mesh (not shown) formed at a predetermined pitch, and the oil drawn up from the inlet 37 can be filtered by passing it through the mesh. This removes foreign matter from the oil. The inlet 37 also communicates with a communication hole 45 in the partition wall 40, which will be described later.

[0038] As shown in Figure 4, a valve body 60 is provided above the oil pan 35. The valve body 60 forms a hydraulic circuit and has a valve built in. The valve body 60 converts oil filtered by the strainer 36 into a predetermined hydraulic pressure in the hydraulic circuit and then sends the oil to each part.

[0039] In this embodiment, an oil injection nozzle 31 (see FIG. 1) is provided in an area between the primary pulley 15 and the secondary pulley 25 and inside the steel belt 30. The injection nozzle 31 can inject oil supplied from the valve body 60 toward the steel belt 30. This allows the steel belt 30 to be lubricated by the oil.

[0040] The above is the configuration of the continuously variable transmission 2. Next, the oil circulation structure 1 according to one embodiment of the present invention will be described in detail. The oil circulation structure 1 is formed by dividing it into a first oil circulation structure 1A (also referred to as oil circulation structure 1A) and a second oil circulation structure 1B (also referred to as oil circulation structure 1B). The oil circulation structure 1A has a configuration in which a communication hole 45 is opened in a partition wall 40 provided on the circumferential outer side below the primary pulley 15. The oil circulation structure 1B has a configuration in which a detour path 51 is provided inside the oil pan 35 to bypass oil. Below, the oil circulation structure 1A and the oil circulation structure 1B will be described in detail in order.

[0041] <First oil circulation structure> 2, the oil circulation structure 1A includes the primary pulley 15, the secondary pulley 25, the steel belt 30, and the oil pan 35 of the continuously variable transmission 2. In addition to the above, the oil circulation structure 1A also includes a partition wall 40 that separates a pulley arrangement area 41 in which the primary pulley 15 is arranged from an area below the pulley arrangement area 41.

[0042] The partition wall 40 is curved downward in a convex shape. In this embodiment, the partition wall 40 is curved to follow the circumferential direction of the primary pulley 15. As described above, the partition wall 40 serves as a partition wall that separates the pulley arrangement area 41 from the oil pan 35, which is an area below the pulley arrangement area 41. Therefore, oil from the oil pan 35 does not directly enter the pulley arrangement area 41. Note that the oil delivered from the valve body 60 and the oil injected from the injection nozzle 31 are stored on the pulley arrangement area 41 side of the partition wall 40 (also simply referred to as above the partition wall 40). As a result, a portion of the lower side of the primary pulley 15 is immersed in oil.

[0043] Additionally, an opening 43 is formed in the partition wall 40, opening toward the rotational direction of the primary pulley 15. The opening 43 is formed to open toward the secondary pulley 25, which is disposed above. The opening 43 allows oil accumulated on the partition wall 40 to overflow from the open end. The overflowing oil flows through an appropriate passage (in this embodiment, an outflow hole 3B, which will be described later) and returns to the oil pan 35. As described above, by opening the opening 43 toward the rotational direction, the rotational resistance of the primary pulley 15 is reduced. Specifically, as the primary pulley 15 rotates, the oil flows out of the opening 43 while moving circumferentially around the partition wall 40, reducing the agitation resistance of the oil and reducing the rotational resistance of the primary pulley 15. This is expected to improve fuel efficiency of the vehicle.

[0044] Furthermore, a communication hole 45 is formed on the lower end side of the partition wall 40, which is open to allow oil to flow out toward the oil pan 35. In this embodiment, the communication hole 45 is formed at the lowest end of the partition wall 40. The communication hole 45 is formed near the center of the partition wall 40 in the width direction (axial direction of the primary pulley 15).

[0045] In the present embodiment, the communication hole 45 communicates with the suction port 37 of the strainer 36. Therefore, a portion of the oil accumulated on the partition wall 40 is discharged toward the suction port 37 of the strainer 36. In the present embodiment, as shown in FIG. 3 , a partition 50 serving as a second oil circulation structure 1B (described later) is formed between the communication hole 45 and the suction port 37. Therefore, the communication hole 45 communicates with the suction port 37 via a bypass path 51 formed by the partition 50. Note that the communication hole 45 may not only be indirectly connected to the suction port 37 of the strainer 36 via the bypass path 51 as in the present embodiment, but may also be directly connected. The diameter of the communication hole 45 can be varied depending on the characteristics of the oil used, the amount of oil supplied, and the required discharge amount, and the oil agitation resistance of the pulley may also be taken into consideration.

[0046] Here, the oil that has accumulated on the partition wall 40 becomes cloudy due to air being mixed in with it and air bubbles are generated due to the spray from the spray nozzle 31 and the rotation of the steel belt 30 and primary pulley 15. As a result, oil with a high air bubble rate containing a lot of air accumulates in the upper layer near the liquid surface (near the two-dot chain line in Figure 2). In addition, because air in oil is light and easily rises, the air bubble rate in the upper layer oil becomes even higher.

[0047] On the other hand, oil with a low air bubble content is intended to accumulate in the lower layer where the communication holes 45 are opened. Therefore, the oil circulation structure 1A of the present invention can discharge oil that has accumulated on the partition wall 40 and that is separated from the liquid surface and contains little air (has a low air bubble content) through the communication holes 45 to the strainer 36 (oil pan 35). Furthermore, because the oil circulation structure 1A can circulate oil with a low air bubble content, it is possible to maintain an appropriate oil hydraulic pressure and prevent shifting problems in the transmission 2. Furthermore, because the air bubble content of the oil in the oil pan 35 can be reduced, it is expected that noise generated when the oil pump draws up oil can be suppressed.

[0048] Furthermore, in the oil circulation structure 1A of the present invention, oil that has accumulated on the partition wall 40 is returned to the oil pan 35 through the communication hole 45, thereby preventing a decrease in the amount of oil in the oil pan 35. As a result, the oil circulation structure 1A of the present invention can prevent air from being trapped in the oil pump, and is expected to have the effect of suppressing abnormal noise when the oil pump sucks up oil. Furthermore, since the amount of oil filled into the transmission 2 can be reduced, the cost of the transmission 2 can be reduced.

[0049] Furthermore, in the oil circulation structure 1A of the present invention, the respective axes of the primary pulley 15 and the secondary pulley 25 are offset to one side and the other in the vertical direction, so that only the pulley on one side (the primary pulley 15 in this embodiment) is immersed in oil. As a result, the oil circulation structure 1A of the present invention can reduce the oil agitation resistance caused by the pulley, and therefore, improved fuel efficiency in the vehicle can be expected. Furthermore, the partition wall 40 separates the pulley arrangement area 41 from the area below the pulley arrangement area 41, so that the primary pulley 15 is separated from the oil in the oil pan 35. As a result, the oil circulation structure 1A of the present invention can reduce the oil agitation resistance, and therefore, improved fuel efficiency in the vehicle can be expected.

[0050] Moreover, in this embodiment, the communication hole 45 is communicated with the suction port 37 of the strainer 36. Therefore, the oil circulation structure 1A of the present invention can supply oil with a low bubble content toward the suction port 37 of the strainer 36, thereby suppressing a shortage of oil being sucked up by the strainer 36. As a result, the oil circulation structure 1A of the present invention can suppress the occurrence of gear shifting problems and damage to various parts. Furthermore, because oil with a low bubble content is filtered by the strainer 36, it is also possible to suppress abnormal noises when the oil pump breaks bubbles and when the oil pump sucks up oil into the strainer 36.

[0051] Furthermore, in this embodiment, the partition wall 40 is formed in a curved shape so as to follow the circumferential direction of the primary pulley 15. Therefore, the oil circulation structure 1A of the present invention can agitate oil along the circumferential direction of the primary pulley 15, thereby reducing the agitation resistance of the oil at the pulley. This is expected to improve the fuel efficiency of the vehicle. Furthermore, the oil circulation structure 1A of the present invention can collect oil that has accumulated on the partition wall 40 downward. This effectively separates the oil with a high porosity that has accumulated on the upper layer (liquid surface side) from the oil with a low porosity on the lower layer. Furthermore, the oil with a low porosity is discharged to the oil pan 35 through the communication hole 45. Therefore, the oil circulation structure 1A of the present invention can circulate oil with a low porosity, thereby maintaining an appropriate oil hydraulic pressure and suppressing shifting problems in the transmission 2.

[0052] Note that partition wall 40 need not necessarily be formed in a curved shape that follows the circumferential direction of primary pulley 15, but may also be formed in a curved or bent shape that is convex downward. By forming partition wall 40 in a downwardly convex shape in this way, oil with a low air void content that accumulates on partition wall 40 can be collected to the lower side, as in the above-described embodiment. Here, the degree of curvature or bending can be changed as appropriate, but it is preferable to change it within a range that does not cause excessive rotational resistance of primary pulley 15.

[0053] As described above, the oil circulation structure 1A of the present invention can suppress the circulation of oil with a high air bubble content, thereby optimizing the oil circulation flow rate. Therefore, the oil circulation structure 1A of the present invention can maintain appropriate oil pressure and suppress gear shifting problems in the transmission. Furthermore, the oil circulation structure 1A of the present invention can suppress air entrapment in the oil pump, thereby suppressing abnormal noise from the oil pump.

[0054] The above is the configuration of the first oil circulation structure 1A, and next, the second oil circulation structure 1B will be described in detail.

[0055] <Second oil circulation structure> 3 and 4, the oil circulation structure 1B includes a case 3, an oil pan 35, and a strainer 36. In addition to the above, the oil circulation structure 1B also includes an intake port 37 of the strainer 36, a partition 50, a bypass path 51 formed by the partition 50, a magnet member 52, a valve body 60, and the like.

[0056] As described above, the case 3 has a bottom wall 3A. The bottom wall 3A of the case 3 is formed to separate the inside and outside of the case 3 and seal the case 3. Therefore, oil supplied into the case 3 from the injection nozzle 31 or the like is stored on the bottom wall 3A. In addition, an outflow hole 3B is formed near the center of the bottom wall 3A, which opens to allow oil to flow out toward the oil pan 35. The oil stored on the bottom wall 3A is returned to the oil pan 35 through the outflow hole 3B. In this embodiment, two outflow holes 3B are formed.

[0057] FIG. 3 is a bottom view of the oil circulation structure 1B with the oil pan 35 removed. A partition 50 is provided inside the oil pan 35 between the suction port 37 of the strainer 36 and the outlet hole 3B of the case 3. In this embodiment, the partition 50 is formed of a plate-like member, and its middle portion is bent into an L-shape. The partition 50 extends from the lower end (lower surface) of the valve body 60 to the bottom of the oil pan 35. Therefore, the partition 50 can suppress deformation of the oil pan 35 when the bottom of the oil pan 35 receives an impact. In other words, in the oil circulation structure 1B of the present invention, the partition 50 braces between the bottom of the oil pan 35 and the valve body 60 when the bottom of the oil pan 35 receives an impact. Therefore, the oil circulation structure 1 of the present invention can suppress deformation of the oil pan 35 even when the vehicle is traveling on a rough road (a road with many bumps and dips), thereby enabling the transmission 2 to operate stably. In addition, it is expected that the oil pan protector for suppressing deformation of the oil pan 35 can be simplified or eliminated, which is expected to contribute to reducing the weight of the vehicle.

[0058] The partition 50 also forms a detour 51 that diverts oil flowing out of the outlet hole 3B and guides it to the suction port 37. In other words, the oil flowing out of the outlet hole 3B is not directly drawn into the suction port 37, but travels a certain distance through the detour 51 as indicated by the arrow in the figure before being drawn into the suction port 37. Therefore, air bubbles are separated from oil with a high air bubble content that flows out of the outlet hole 3B while passing through the detour 51. This allows the oil circulation structure 1B of the present invention to circulate oil with a low air bubble content, thereby maintaining an appropriate oil pressure and preventing shifting problems in the transmission 2. Furthermore, the oil circulation structure 1B of the present invention can reduce the air bubble content of the oil drawn into the suction port 37 of the strainer 36, thereby preventing noise generated when air bubbles are crushed by the strainer 36. This is also expected to reduce noise generated when an oil pump (not shown) draws up oil. The distance of the detour 51 formed by the partition 50 can be changed as appropriate depending on the characteristics of the oil and the configuration of the transmission 2.

[0059] Additionally, a magnet member 52 is provided on the route of the detour 51. The magnet member 52 is configured to remove foreign matter, such as iron powder, mixed in with the oil passing over the magnet member 52. That is, the oil circulation structure 1B of the present invention can remove iron powder from the oil supplied to the transmission 2 (gear change unit 2A). As a result, the oil circulation structure 1B of the present invention can suppress shifting problems in the transmission 2 due to the inclusion of foreign matter. Furthermore, the oil circulation structure 1B of the present invention can double as the magnet member 52 and a drain bolt, which makes it easy to discharge metal powder attracted to the magnet member 52, for example, during an oil change. Furthermore, by forming the magnet member 52 as a drain bolt, the installation space for the magnet member 52 can be consolidated, which is expected to lead to a more compact transmission 2.

[0060] The above are embodiments of the oil circulation structure 1 (first oil circulation structure 1A and second oil circulation structure 1B) of the present invention, but the oil circulation structure 1 of the present invention is not limited to the above-mentioned embodiments and can be modified in various ways.

[0061] In this embodiment, the communication hole 45 is formed at the lowest end of the partition wall 40. However, for example, the communication hole 45 may be formed between the lowest end of the partition wall 40 and the opening 43. In such a case, oil is discharged from the communication hole 45 in accordance with the rotation of the primary pulley 15 on the partition wall 40 side. This allows the oil circulation structure 1 of the present invention to further reduce the oil stirring resistance. In addition, the backflow of oil due to the proximity of the communication hole 45 and the oil suction port 37 can also be suppressed.

[0062] Furthermore, the communication hole 45 can be formed in various positions taking into consideration the rotational resistance and porosity of the pulley, or the prevention of backflow of oil from the oil pan 35. The shape and size of the communication hole 45 can be changed as appropriate depending on the oil characteristics and the shape and size of the transmission 2. The opening 43 can be formed in various positions depending on the oil characteristics and the shape of the transmission 2. Furthermore, the communication hole 45 need not be a single hole, and multiple holes may be formed.

[0063] In the present embodiment, the primary pulley 15 is disposed on the lower side in the vertical direction, but the primary pulley 15 and the secondary pulley 25 may be disposed upside down. In addition, in the present embodiment, a steel belt 30 is exemplified as the endless belt 30, but belts made of various materials can be used for the endless belt 30. In addition, in the present embodiment, the respective axial centers of the primary pulley 15 and the secondary pulley 25 are exemplified as being offset in the vertical direction, but the amount of offset can be changed as appropriate depending on the shape and size of the transmission 2, the position where the oil pan 35 is disposed, etc.

[0064] The partition wall 40 may be curved or bent downward in a convex shape or formed in a curved shape along the circumferential direction of the pulley, and may be formed in various shapes and sizes. In the present embodiment, the partition wall 40 is formed so as to surround the primary pulley 15, but the partition wall 40 may be formed so as to surround at least a portion of the secondary pulley 25 together with the primary pulley 15.

[0065] In the present embodiment, the strainer 36 is disposed within the oil pan 35, and the communication hole 45 is indirectly connected to the suction port 37 of the strainer 36. However, the communication hole 45 may be directly connected to the suction port 37 of the strainer 36. The strainer 36 may be provided as needed, and a configuration without the strainer 36 is also possible. In the present embodiment, the strainer 36 is disposed within the oil pan 35, but the strainer 36 can be disposed in various positions. For example, the strainer 36 can be disposed above the oil pan 35 or outside the oil pan 35.

[0066] Furthermore, the first oil circulation structure 1A of the present invention can be preferably employed in various CVTs. The oil circulation structure 1 of the present invention is not limited to a vertically mounted CVT, but may also be employed in a horizontally mounted CVT. Furthermore, although a belt-type CVT is exemplified in this embodiment, the oil circulation structure 1 of the present invention may be employed in a chain-type or toroidal-type CVT, for example, in addition to the belt-type CVT.

[0067] The case 3 that houses the transmission unit 2A can be made in various shapes and sizes to suit the shape and size of the transmission unit 2A. The oil pan 35 and strainer 36 can be made in various shapes and sizes to suit the configuration of the transmission 2. The positions of the oil pan 35 and strainer 36 can be changed as needed. The outlet hole 3B of the case 3 and the suction port 37 of the strainer 36 can be made in various shapes and sizes. The partition 50 can be made in various shapes and sizes as long as it can form the detour 51. For example, the partition 50 can be unbent or formed as a thick protrusion rather than a plate-like member. The distance of the detour 51 formed by the partition 50 can be changed as needed depending on the oil characteristics, the structure of the transmission 2, and the like. The partition 50 can be provided in various ways, such as being formed integrally with the oil pan 35 or being formed separately from the oil pan 35. Furthermore, the outlet hole 3B and the suction port 37 may not be limited to a single one, but may be formed in plural.

[0068] In this embodiment, the magnet member 52 is disposed on the route of the detour 51, but the oil circulation structure 1 of the present invention is not limited to this, and the magnet member 52 can be disposed in various positions. Furthermore, the magnet member 52 is not limited to being formed as a drain bolt, and various other shapes can be used. Furthermore, the magnet member 52 may be provided in a single number or in multiple numbers, and a configuration without the magnet member 52 is also possible.

[0069] In the present embodiment, the valve body 60 is disposed above the oil pan 35, but the valve body 60 can be disposed in various positions. In addition, in the present embodiment, the partition portion 50 is formed from the lower end side of the valve body 60 to the bottom of the oil pan 35, but the location, size, shape, etc. of the partition portion 50 can be changed as appropriate depending on the mode of suppressing deformation of the oil pan 35. In addition, the second oil circulation structure 1B of the present invention is not limited to CVTs and can be used in various transmissions.

[0070] In addition, in this embodiment, an example has been given in which both the first oil circulation structure 1A and the second oil circulation structure 1B are adopted, but it is also possible to adopt a configuration in which only one of the first oil circulation structure 1A and the second oil circulation structure 1B is adopted.

[0071] The above are various embodiments and modifications of the oil circulation structure according to the present invention, but the present invention is not limited to the above-described embodiments and modifications, and it will be easily understood by those skilled in the art that other embodiments are possible within the scope of the claims and the teachings and spirit of the present invention. [Industrial Applicability]

[0072] The oil circulation structure of the present invention can be used in various transmissions of vehicles, etc., and can be particularly preferably used in CVTs (continuously variable transmissions). [Explanation of symbols]

[0073] 1: Oil circulation structure 1A: First oil circulation structure 1B: Second oil circulation structure 2: Transmission (Continuously Variable Transmission) 2A: Transmission unit (transmission mechanism) 3: Case 3A: Bottom wall 3B:Outflow hole 15: Primary pulley 25: Secondary pulley 30: Steel belt (endless belt) 35: Oil pan 36: Strainer 37: Inlet 40: Bulkhead 41: Pulley placement area 43: Opening 45:Communication hole 50: Partition 51: Detour 52: Magnet parts

Claims

1. An oil circulation structure for a transmission mounted on a vehicle, a case that houses a transmission unit in the transmission; an oil pan disposed below the case; a strainer disposed in the oil pan, The strainer has a suction port for sucking up oil stored in the oil pan, the case has an outflow hole that opens toward the oil pan to allow the oil to flow out, A partition is provided between the suction port and the outlet hole, The partition portion forms a detour path for guiding the oil flowing out from the outflow hole to the suction port, a magnet member is disposed on the route of the detour; The oil circulation structure is characterized in that the partition portion is formed so as to extend to a position where it overlaps with the magnet member.

2. A valve body that forms a hydraulic circuit is disposed above the oil pan.

2. The oil circulation structure according to claim 1, wherein the partition portion is formed from a lower end side of the valve body to a bottom portion of the oil pan.

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