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 1 includes: a primary pulley 15; a secondary pulley 25; an endless belt 30 wound around the primary pulley 15 and the secondary pulley 25; and an oil pan 35 disposed at the lower end side of a transmission 2. The primary pulley 15 and the secondary pulley 25 are arranged with their axes respectively offset to one side and the other side in a vertical direction. Further, the oil circulation structure 1 has a partition wall 40 for partitioning a pulley arrangement area 41 arranged with the pulley, which is disposed at the relatively lower side, of the primary pulley 15 and the secondary pulley 25 from an area located at the lower side relative to the pulley arrangement area 41. The partition wall 40 allows at least part of an oil to be stored at the pulley arrangement area 41 side and is formed with a communication hole 45 which is open to allow the oil to flow toward the oil pan 35.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present invention relates to an oil circulation structure of a transmission. 【Background Art】 【0002】 Conventionally, a CVT (Continuously Variable Transmission) has been adopted as a transmission for various vehicles (for example, Patent Document 1). The CVT described in Patent Document 1 mentioned above includes a primary pulley to which power from a drive source such as an engine is input, a secondary pulley that outputs the transmitted power, and an endless steel belt wound around the primary pulley and the secondary pulley. Further, an oil pan is provided at the bottom of the CVT described in Patent Document 1 mentioned above, and oil as hydraulic oil and lubricating oil is stored in the oil pan. 【0003】 The CVT (transmission) described in Patent Document 1 mentioned above includes a case constituting an outer shell, an input shaft to which power from a drive source is input, a primary shaft that extends parallel to the input shaft and to which power is transmitted from the input shaft, a secondary shaft that extends parallel to the primary shaft with a gap in the axial diameter direction with respect to the primary shaft, a primary pulley supported by the primary shaft, a secondary pulley supported by the secondary shaft, and an endless belt wound around the primary pulley and the secondary pulley. The primary shaft and the secondary shaft are arranged offset on one side and the other side in the vertical direction with respect to the input shaft, and a partition wall is integrally formed in the case to isolate at least the primary pulley or the secondary pulley arranged at a relatively lower position from the oil stored in the case. That is, the CVT described in Patent Document 1 mentioned above is configured to isolate a primary pulley or a secondary pulley (simply referred to as a pulley) arranged relatively downward from the oil stored in the case by a partition wall. 【0004】 Furthermore, in the CVT described in Patent Document 1 mentioned above, oil is supplied to the pulleys and belt for lubrication, and a portion of the oil after lubrication accumulates in the pulley-side (inner) region of the partition wall. The oil accumulated in the pulley-side region of the partition wall overflows and is returned to the oil pan. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Japanese Patent Publication No. 2020-180644 [Overview of the Initiative] [Problems that the invention aims to solve] 【0006】 Incidentally, in the CVT described in Patent Document 1, the oil is struck against the belt and pulleys, and agitated by their rotation. As a result, air is mixed into the oil, generating bubbles, and oil with a high bubble ratio (for example, cloudy oil) is produced. Furthermore, in the CVT described in Patent Document 1, a portion of the aforementioned oil is said to accumulate in the area on the pulley side (above the partition wall). As a result, oil containing many bubbles concentrates near the oil surface of the oil accumulated on the partition wall. Here, in the CVT described in Patent Document 1, as mentioned above, the oil accumulated on the partition wall overflows and is returned to the oil pan. In other words, oil with a high bubble ratio is returned to the oil pan while overflowing. 【0007】 However, oils with a high bubble rate have properties such as viscosity that differ from their intended characteristics, leading to problems such as abnormal noise and a drop in oil pressure. As a result, there is a concern that the CVT described in Patent Document 1 may cause shifting problems. 【0008】 Furthermore, the oil pump in a CVT is generally driven by engine power. For example, at low engine speeds such as in N (neutral) or P (parking) range, the pump speed decreases, reducing the oil circulation flow rate. As a result, the amount of oil returning to the oil pan decreases, and there is a concern that the oil pump may draw in air, leading to abnormal noises and a drop in oil pressure. Moreover, there is a concern that the supply of oil containing many air bubbles, as mentioned above, will make it even easier for insufficient oil supply to occur. 【0009】 Therefore, the present invention aims to provide a transmission oil circulation structure that can optimize the oil circulation flow rate by suppressing the circulation of oil mixed with air. [Means for solving the problem] 【0010】 (1) The oil circulation structure of the present invention, provided to solve the above-mentioned problems, is an oil circulation structure for a transmission mounted on a vehicle, comprising: a primary pulley that is rotationally driven in accordance with the input of power from a drive source; a secondary pulley that outputs the shifted power; an endless belt stretched between the primary pulley and the secondary pulley; and an oil pan disposed on the lower end side of the transmission and storing the oil filled in the transmission, wherein the primary pulley and the secondary pulley are arranged with their respective axes offset to one side and the other side in the vertical direction, and there is a partition wall separating a pulley arrangement region where the pulley that is relatively lower than the primary pulley or the secondary pulley is arranged from a region below the pulley arrangement region, and the partition wall is capable of storing at least a portion of the oil on the pulley arrangement region side and has a communication hole formed therein that opens to allow the oil to flow out toward the oil pan. 【0011】 The oil circulation structure described above has a partition wall separating a pulley arrangement region where the primary or secondary pulley, which is positioned relatively lower, is located, from a region below the said pulley arrangement region. The partition wall also has a communication hole formed therein that allows oil to flow out toward the oil pan. Therefore, the oil circulation structure described above can discharge oil with a low air content (low bubble rate) that is separated from the liquid surface from the oil that has accumulated on the pulley arrangement region side of the partition wall, into the oil pan through the communication hole. Furthermore, because the oil circulation structure described above can circulate oil with a low bubble rate, it is possible to maintain the oil pressure properly and suppress shifting problems in the transmission. In addition, since the bubble rate of the oil in the oil pan can be reduced, it is expected that the abnormal noise when the oil pump draws up oil will be suppressed. 【0012】 Furthermore, the aforementioned oil circulation structure allows oil accumulated on the pulley placement side of the partition wall to be returned to the oil pan through the communication holes, thereby suppressing a decrease in the oil level in the oil pan. As a result, the aforementioned oil circulation structure can suppress air entrapment in the oil pump and is expected to reduce abnormal noise when the oil pump draws up oil. In addition, it can reduce the amount of oil that needs to be filled into the transmission, which is expected to lower the cost of the transmission. 【0013】 Furthermore, in the oil circulation structure described above, the axes of the primary and secondary pulleys are offset to one and the other in the vertical direction, so that only the pulley on one side is immersed in the oil. As a result, the oil circulation structure described above can reduce the resistance of oil stirring by the pulleys, and thus fuel efficiency can be expected to improve. In addition, the pulley arrangement area is separated from the area below the pulley arrangement area by a partition wall, so the pulleys are separated from the oil in the oil pan. As a result, the oil circulation structure described above can reduce the resistance of oil stirring, and thus fuel efficiency can be expected to improve. 【0014】 (2) The oil circulation structure of the present invention described above is preferably such that the partition wall is curved or bent in a convex shape toward downward. 【0015】 The oil circulation structure described above, with this configuration, can collect the oil accumulated on the pulley placement side of the partition wall on the lower side. As a result, the oil circulation structure described above can effectively separate the oil with a high air content (high bubble rate) accumulated on the upper layer (liquid surface side) from the oil with a low air content (low bubble rate) on the lower layer. Furthermore, the oil with a low bubble rate is discharged towards the oil pan through the communication holes. Therefore, since the oil circulation structure described above can circulate oil with a low bubble rate, it can maintain the oil pressure appropriately and suppress transmission malfunctions. 【0016】 (3) In the oil circulation structure of the present invention described above, it is preferable that the partition wall is formed in a curved shape so as to follow the circumferential direction of the pulley. 【0017】 The oil circulation structure described above, by having this configuration, agitates the oil along the circumferential direction of the pulley. Therefore, the oil circulation structure described above can reduce the resistance to oil agitation by the pulley. This is expected to improve fuel efficiency in the vehicle. In addition, the oil circulation structure described above can collect the oil accumulated on the pulley-placed side of the partition wall (above the partition wall) on the lower side. As a result, the oil circulation structure described above can effectively separate the oil with a high bubble rate accumulated on the upper layer (liquid surface side) from the oil with a low bubble rate on the lower layer. Furthermore, the oil with a low bubble rate is discharged to the oil pan through the communication hole. Therefore, since the oil circulation structure described above can circulate oil with a low bubble rate, it is possible to maintain the oil pressure appropriately and suppress transmission malfunctions. 【0018】 (4) In the oil circulation structure of the present invention described above, it is preferable that the communication hole is formed at the lowest end of the partition wall. 【0019】 The oil circulation structure described above, with this configuration, can discharge oil with a low bubble rate through the communication hole. As a result, the oil circulation structure described above can suppress the generation of abnormal noise from the oil pump and suppress transmission shifting problems. 【0020】 (5) The oil circulation structure of the present invention described above is provided in which a strainer is placed in the oil pan, the strainer has a suction port for drawing in oil from the oil pan, and the communication hole is in communication with the suction port. 【0021】 In the oil circulation structure described above, the communication hole is connected to the suction port of the strainer. Therefore, the oil circulation structure described above can supply oil with a low bubble rate to the suction port of the strainer, thereby suppressing insufficient oil supply to be drawn up by the strainer. As a result, the oil circulation structure described above can suppress the occurrence of shifting malfunctions and damage to various parts. In addition, since the oil with a low bubble rate is filtered by the strainer, abnormal noise when bubbles are broken up by the strainer and abnormal noise when the oil pump draws oil up to the strainer can also be suppressed. 【0022】 (6) In the oil circulation structure of the present invention described above, the partition wall has an opening that opens toward the rotational direction of the primary pulley or the secondary pulley which is positioned relatively lower, the opening is formed toward the primary pulley or the secondary pulley which is positioned relatively upper, and the communication hole is preferably formed between the lowest end of the partition wall and the opening. 【0023】 In the partition wall in the above-described oil circulation structure, an opening is formed that opens in the rotational direction of a primary pulley or a secondary pulley (also simply referred to as a partition wall side pulley) that is relatively arranged on the lower side. Therefore, the oil accumulated on the pulley arrangement region side of the partition wall overflows from the opening as the partition wall side pulley rotates. That is, the overflow of oil from the opening is promoted, and the rotational resistance of the partition wall side pulley is reduced. Further, since the opening is formed to open toward the primary pulley or the secondary pulley that is relatively arranged on the upper side, only one of the primary pulley or the secondary pulley can be immersed in the oil. Therefore, the above-described oil circulation structure can reduce the stirring resistance of the oil. 【0024】 Further, since the communication hole is formed between the lowermost end of the partition wall and the opening, oil is discharged from the communication hole according to the rotation of the partition wall side pulley. Thereby, the above-described oil circulation structure can reduce the stirring resistance of the oil. Also, it is possible to suppress the backflow of oil due to the proximity of the communication hole and the oil suction port. Further, since the above-described oil circulation structure can discharge oil with a low bubble rate from the communication hole, it is possible to suppress the occurrence of shift failure. 【Effect of the Invention】 【0025】 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 mixed with air. 【Brief Description of the Drawings】 【0026】 [Figure 1] It is a cross-sectional view of a continuously variable transmission adopting the oil circulation structure of the present invention as viewed from above. [Figure 2] It is a partially cutaway perspective view of a continuously variable transmission adopting the oil circulation structure of the present invention as viewed from the rear. [Figure 3] It is a bottom view of the oil circulation structure of the present invention with the oil pan removed. [Figure 4] It is a cross-sectional view taken along the arrow A-A direction in FIG. 2. [Modes for carrying out the invention] 【0027】 The oil circulation structure 1 according to an embodiment of the present invention will be described below with reference to Figures 1 to 4. In this embodiment, the case in which the oil circulation structure 1 of the present invention is applied to a continuously variable transmission 2 (CVT) as a transmission 2 will be described as an example. Furthermore, the continuously variable transmission 2 will be described as being connected to an engine (not shown) as a drive source. Also, please note that the oil is omitted in each figure. 【0028】 In order to explain the oil circulation structure 1, we will first describe in detail the continuously variable transmission 2, which is a part of the oil circulation structure 1. 【0029】 Figure 1 is a cross-sectional view of the continuously variable transmission 2 seen from above. Figure 2 is a perspective view of the continuously variable transmission 2 with a portion of the case 3 cut out, seen from the rear of the vehicle. Figure 3 is a bottom view of the continuously variable transmission 2 seen from the bottom with the oil pan 35 removed. Note that the primary shaft 10 is omitted in Figure 2. 【0030】 The continuously variable transmission (CVT) 2 is mounted on a vehicle (not shown) and outputs power from an engine (not shown) by changing the speed. As shown in Figure 1, the CVT 2 comprises a case 3 forming the outer shell, a primary shaft 10, a primary pulley 15 supported by the primary shaft 10, a secondary shaft 20 provided parallel to the primary shaft 10, a secondary pulley 25 supported by the secondary shaft 20, and a steel belt 30 (also referred to as an endless belt 30) stretched between the primary pulley 15 and the secondary pulley 25. In addition to the above, the CVT 2 also comprises an oil pan 35, a strainer 36 (see Figure 3), a valve body 60, etc., as shown in Figure 4. In this embodiment, the CVT 2 is a longitudinally mounted CVT arranged along the longitudinal direction of the vehicle. 【0031】 As shown in Figures 1 and 2, Case 3 is formed as the main frame of the continuously variable transmission 2 and is cylindrical in shape so as to be able to integrally house the transmission unit 2A (transmission mechanism 2A), including the primary shaft 10, primary pulley 15, secondary shaft 20, secondary pulley 25, and steel belt 30. 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. Case 3 can also store a portion of oil (also called lubricating oil, including fluid) inside. 【0032】 The primary shaft 10 (see Figure 1) is connected to an input shaft (not shown) that transmits power output from the engine, via an appropriate clutch (not shown), etc. Therefore, power output from the engine is input to the primary shaft 10. The primary shaft 10 is positioned such that its axis is located to the lower right when viewed from the rear of the vehicle. Therefore, the primary shaft 10 is positioned offset downward in the vertical direction relative to the secondary shaft 20, which will be described later. 【0033】 As shown in Figure 1, the primary pulley 15 comprises a movable primary movable sheave 16 and a fixed primary fixed sheave 17. The primary movable sheave 16 and the primary fixed sheave 17 are arranged opposite each other via a steel belt 30. In this embodiment, the primary movable sheave 16 is located on the front side of the vehicle (in the rear of the figure), and the primary fixed sheave 17 is located on the rear side of the vehicle (in the front of the figure). Furthermore, the opposing surfaces of the primary movable sheave 16 and the primary fixed sheave are formed in a conical shape. 【0034】 The primary movable sheave 16 is rotatably supported on the primary shaft 10 and can rotate integrally with the primary shaft 10. In this embodiment, the primary pulley 15 is set to rotate in the direction of the arrow shown in Figure 2 (clockwise when viewed from the rear of the vehicle). Therefore, the primary shaft 10 is rotationally driven in response to the power input from the engine, and the primary pulley 15 is rotationally driven accordingly. The primary movable sheave 16 is also movable in the axial direction of the primary shaft 10 by the primary piston 18. 【0035】 Furthermore, the primary piston 18 can move the primary movable sheave 16 closer to and further away from the primary fixed sheave 17. A steel belt 30 is positioned between the primary movable sheave 16 and the primary fixed sheave, and by driving the primary movable sheave 16 toward the primary fixed sheave 17, the steel belt 30 is held between the primary movable sheave 16 and the primary fixed sheave. As a result, the power input to the primary shaft 10 is transmitted to the steel belt 30. 【0036】 The secondary shaft 20 is positioned parallel to the primary shaft 10 and offset upward relative to the primary shaft 10 (see Figure 2). In other words, the primary pulley 15 and the secondary pulley 25 are positioned with their respective axes (primary shaft 10 and secondary shaft 20) offset to one side (upwards) and the other side (downwards) in the vertical direction. 【0037】 The secondary pulley 25 comprises a movable secondary movable sheave 26 and a fixed secondary fixed sheave 27. The secondary movable sheave 26 and the secondary fixed sheave 27 are arranged opposite each other via a steel belt 30. In this embodiment, the secondary fixed sheave 27 is located on the front side of the vehicle (in the rear in the figure), and the secondary movable sheave 26 is located on the rear side of the vehicle (in the front in the figure). That is, the secondary movable sheave 26 and the secondary fixed sheave 27 are arranged in the opposite direction to the primary movable sheave 16 and the primary fixed sheave 17. Furthermore, the opposing surfaces of the secondary movable sheave 26 and the secondary fixed sheave 27 are formed in a conical shape. 【0038】 The secondary movable 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 Figure 2 (clockwise when viewed from the rear of the vehicle). Therefore, the primary pulley 15 is rotationally driven, and consequently, the secondary pulley 25 is rotationally driven. The secondary movable sheave 26 is also movable in the axial direction of the secondary shaft 20 by the secondary piston 28. 【0039】 Furthermore, the secondary piston 28 can move the secondary movable sheave 26 closer to and further away from the secondary fixed sheave 27. A steel belt 30 is positioned between the secondary movable sheave 26 and the secondary fixed sheave 27, and by driving the secondary movable sheave 26 toward the secondary fixed sheave 27, the steel belt 30 is held between the secondary movable sheave 26 and the secondary fixed sheave 27. As a result, the power input to the primary shaft 10 is transmitted to the secondary pulley 25 via the steel belt 30. 【0040】 The steel belt 30 is formed, for example, by supporting a large number of steel links on an endless steel ring. The steel belt 30 is stretched over 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 continuously and steplessly changed within a predetermined range of gear ratios by changing the groove widths of the primary pulley 15 and the secondary pulley 25. That is, the power input to the input shaft is shifted by the continuously variable transmission 2, and the shifted power is output from the secondary shaft 20. 【0041】 As shown in Figure 4, the oil pan 35 is located in the area at the lower end of the continuously variable transmission 2. The oil pan 35 can store oil (also called fluid) filled as hydraulic fluid and lubricant for the continuously variable transmission 2. The oil pan 35 is mounted in the case 3 in a liquid-tight manner by appropriate seals (not shown). 【0042】 As shown in Figure 3, the strainer 36 is located inside the oil pan 35. The strainer 36 has a suction port 37 for drawing oil from the oil pan 35. The suction port 37 opens toward the bottom. The suction port 37 can draw oil from the oil pan 35 using the hydraulic pressure generated by the operation of the oil pump. The strainer 36 incorporates a mesh (not shown) formed at a predetermined pitch, and the oil drawn up from the suction port 37 can be filtered by passing it through the mesh. This removes foreign matter from the oil. The suction port 37 is also in communication with a communication hole 45 of the partition wall 40, which will be described later. 【0043】 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 valves built inside. The valve body 60 converts the oil filtered by the strainer 36 into a predetermined hydraulic pressure in the hydraulic circuit and then supplies it to each part. 【0044】 In this embodiment, an oil injection nozzle 31 (see Figure 1) is provided between the primary pulley 15 and the secondary pulley 25, in the area inside the steel belt 30. The injection nozzle 31 can inject oil supplied from the valve body 60 towards the steel belt 30. As a result, the steel belt 30 is lubricated by the oil. 【0045】 The above describes the configuration of the continuously variable transmission 2. Next, an 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 bypass circuit 51 is provided inside the oil pan 35 to bypass the oil. The oil circulation structure 1A and the oil circulation structure 1B will be described in detail in order below. 【0046】 ≪First Oil Circulation Structure≫ As shown in Figure 2, the oil circulation structure 1A includes a primary pulley 15, a secondary pulley 25, a steel belt 30, and an oil pan 35 in the continuously variable transmission 2. In addition, the oil circulation structure 1A also has a partition wall 40 that separates the pulley arrangement region 41 where the primary pulley 15 is located from the region below the pulley arrangement region 41. 【0047】 The partition wall 40 is curved downwards 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 separating the pulley arrangement region 41 from the oil pan 35, which is the region below the pulley arrangement region 41. Therefore, oil from the oil pan 35 does not directly enter the pulley arrangement region 41. On the pulley arrangement region 41 side of the partition wall 40 (also simply referred to as the top of the partition wall 40), some of the oil supplied from the valve body 60 and some of the oil injected from the injection nozzle 31 is stored. As a result, a portion of the lower side of the primary pulley 15 is immersed in oil. 【0048】 Furthermore, the partition wall 40 has an opening 43 that opens toward the rotational direction of the primary pulley 15. The opening 43 is formed toward the secondary pulley 25 located above it. The opening 43 allows oil accumulated on the partition wall 40 to overflow from its opening. The overflowing oil is returned to the oil pan 35 through an appropriate passage (in this embodiment, the outlet hole 3B described later). As described above, opening the opening 43 toward the rotational direction reduces the rotational resistance of the primary pulley 15. Specifically, as the primary pulley 15 rotates, the oil flows out of the opening 43 while moving along the circumferential direction of the partition wall 40, reducing the oil agitation resistance and thus reducing the rotational resistance of the primary pulley 15. This is expected to improve fuel efficiency in the vehicle. 【0049】 Furthermore, a communication hole 45 is formed at the lower end 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 approximately in the center of the partition wall 40 in the width direction (axis direction of the primary pulley 15). 【0050】 Furthermore, in this 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 this embodiment, as shown in Figure 3, a partition 50, which will be described later as a second oil circulation structure 1B, 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 51 formed by the partition 50. Note that the communication hole 45 can communicate not only indirectly with the suction port 37 of the strainer 36 via the bypass 51 as in this embodiment, but can also communicate directly. Various diameters can be used for the opening of the communication hole 45 according to the characteristics of the oil used, the amount of oil supplied, and the required discharge amount, and the oil stirring resistance of the pulley should also be considered. 【0051】 Here, the oil accumulated on the partition wall 40 becomes cloudy and bubbles form due to air being mixed in by the injection from the injection nozzle 31 and the rotation of the steel belt 30 and primary pulley 15. As a result, the upper layer near the liquid surface (around the dashed line in Figure 2) is assumed to contain a large amount of air and a high bubble ratio. Furthermore, since air in oil is lighter and rises easily, the bubble ratio of the oil in the upper layer becomes even higher. 【0052】 On the other hand, oil with a low bubble rate is expected to accumulate in the lower layer where the communication hole 45 is opened. Therefore, the oil circulation structure 1A of the present invention can discharge oil with a low air content (low bubble rate) that is separated from the liquid surface from the oil accumulated on the partition wall 40 to the strainer 36 (oil pan 35) through the communication hole 45. Furthermore, since the oil circulation structure 1A can circulate oil with a low bubble rate, it is possible to maintain the oil pressure appropriately and suppress shifting malfunctions in the transmission 2. In addition, since the bubble rate of the oil in the oil pan 35 can be reduced, an effect of suppressing abnormal noise when the oil pump draws up oil can be expected. 【0053】 Furthermore, in the oil circulation structure 1A of the present invention, the oil accumulated on the partition wall 40 is returned to the oil pan 35 through the communication hole 45, thereby suppressing a decrease in the oil level in the oil pan 35. As a result, the oil circulation structure 1A of the present invention can suppress air entrapment in the oil pump and is expected to have a noise suppression effect when the oil pump draws up oil. In addition, since the amount of oil to be filled into the transmission 2 can be reduced, a cost reduction for the transmission 2 can be expected. 【0054】 Furthermore, in the oil circulation structure 1A of the present invention, the axes of the primary pulley 15 and the secondary pulley 25 are offset to one side and the other side in the vertical direction, so that only one pulley (primary pulley 15 in this embodiment) is immersed in the oil. As a result, the oil circulation structure 1A of the present invention can reduce the resistance of oil stirring by the pulleys, and thus an improvement in fuel efficiency in the vehicle can be expected. In addition, 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 resistance of oil stirring, and thus an improvement in fuel efficiency in the vehicle can be expected. 【0055】 Furthermore, in this embodiment, the communication hole 45 is connected to 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 rate to the suction port 37 of the strainer 36, thereby suppressing insufficient supply of oil drawn up by the strainer 36. As a result, the oil circulation structure 1A of the present invention can suppress the occurrence of shifting malfunctions and damage to various parts. In addition, since oil with a low bubble rate is filtered by the strainer 36, abnormal noise when bubbles are broken up by the oil pump and abnormal noise when the oil pump draws oil up to the strainer 36 can also be suppressed. 【0056】 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 the oil along the circumferential direction of the primary pulley 15, thereby reducing the resistance to oil agitation in the pulley. This is expected to improve fuel efficiency in the vehicle. In addition, the oil circulation structure 1A of the present invention can collect the oil accumulated on the partition wall 40 to the lower side. This effectively separates the oil with a high bubble rate accumulated on the upper layer (liquid surface side) from the oil with a low bubble rate on the lower layer. The oil with a low bubble rate is then discharged to the oil pan 35 through the communication hole 45. Therefore, since the oil circulation structure 1A of the present invention can circulate oil with a low bubble rate, it is possible to maintain the oil pressure appropriately and suppress shifting problems in the transmission 2. 【0057】 Furthermore, the partition wall 40 may not only be formed in a curved shape along the circumferential direction of the primary pulley 15, but may also be formed in a convex shape toward downwards. By forming the partition wall 40 in a convex shape toward downwards in this way, as in the embodiment described above, oil with a low bubble rate among the oil accumulated on the partition wall 40 can be collected on the downward side. Here, the degree of curvature and bending can be changed as appropriate, but it is best to change it within a range that does not increase the rotational resistance of the primary pulley 15 too much. 【0058】 As described above, the oil circulation structure 1A of the present invention can suppress the circulation of oil with a high bubble rate, thereby optimizing the oil circulation flow rate. Therefore, the oil circulation structure 1A of the present invention can maintain proper oil pressure and suppress transmission shifting malfunctions. Furthermore, the oil circulation structure 1A of the present invention can suppress air entrapment in the oil pump, thus suppressing the generation of abnormal noise in the oil pump. 【0059】 The above describes the configuration of the first oil circulation structure 1A. Next, we will explain the details of the second oil circulation structure 1B. 【0060】 ≪Second Oil Circulation Structure≫ As shown in Figures 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 a suction port 37 of the strainer 36, a partition 50, a bypass 51 formed by the partition 50, a magnetic member 52, a valve body 60, and the like. 【0061】 Case 3 has a bottom wall 3A as described above. The bottom wall 3A in case 3 is formed to separate the inside and outside of case 3, sealing case 3. Therefore, the oil supplied into case 3 from the injection nozzle 31, etc., is stored on the bottom wall 3A. In addition, an outlet 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 outlet hole 3B. In this embodiment, two outlet holes 3B are formed. 【0062】 Figure 3 is a bottom view of the oil circulation structure 1B with the oil pan 35 removed. Inside the oil pan 35, a partition 50 is provided 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, with its middle portion bent into an L-shape. The partition 50 extends from the lower end (bottom 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 is subjected to impact. In other words, in the oil circulation structure 1B of the present invention, when the bottom of the oil pan 35 is subjected to impact, the partition 50 braces between the bottom of the oil pan 35 and the valve body 60. As a result, the oil circulation structure 1 of the present invention can suppress deformation of the oil pan 35 even when the vehicle is traveling on rough roads (roads with many bumps and dips), thereby enabling the transmission 2 to operate stably. Furthermore, it is expected that the oil pan protector, which suppresses deformation of the oil pan 35, can be simplified or eliminated, thus contributing to a reduction in vehicle weight. 【0063】 Furthermore, the partition 50 forms a bypass circuit 51 that diverts the oil flowing out from the outlet hole 3B and guides it to the intake port 37. That is, the oil flowing out from the outlet hole 3B is not directly sucked in from the intake port 37, but rather passes through the bypass circuit 51 for a certain distance as shown by the arrow in the figure before being sucked into the intake port 37. Consequently, the bubbles in the oil with a high bubble rate flowing out from the outlet hole 3B are separated as it passes through the bypass circuit 51. As a result, the oil circulation structure 1B of the present invention can circulate oil with a low bubble rate, thereby maintaining the oil pressure appropriately and suppressing shifting problems in the transmission 2. In addition, the oil circulation structure 1B of the present invention can reduce the bubble rate of the oil sucked into the intake port 37 of the strainer 36, thereby suppressing the generation of abnormal noise when bubbles are crushed in the strainer 36. Furthermore, an effect of suppressing abnormal noise when the oil pump (not shown) draws up oil can be expected. The distance of the bypass 51 formed by the partition 50 can be appropriately changed depending on the characteristics of the oil and the configuration of the transmission 2. 【0064】 Furthermore, a magnetic member 52 is provided along the path of the detour 51. The magnetic member 52 is intended to remove foreign matter such as iron filings that have entered the oil passing over it. In other words, the oil circulation structure 1B of the present invention can remove iron filings from the oil supplied to the transmission 2 (transmission unit 2A). As a result, the oil circulation structure 1B of the present invention can suppress transmission malfunctions of the transmission 2 caused by foreign matter getting stuck. In addition, the oil circulation structure 1B of the present invention can use the magnetic member 52 as both the magnet member 52 and the drain bolt, and with this configuration, for example, metal filings attracted to the magnetic member 52 can be easily discharged when changing the oil. Also, since the magnetic member 52 is formed as a drain bolt, the installation space for the magnetic member 52 can be consolidated, so a miniaturization of the transmission 2 can be expected. 【0065】 The above describes embodiments of the oil circulation structure 1 of the present invention (first oil circulation structure 1A and second oil circulation structure 1B). However, the oil circulation structure 1 of the present invention is not limited to the embodiments described above, and can be modified in various ways. 【0066】 In this embodiment, the communication hole 45 is formed at the lowest end of the partition wall 40, but for example, the communication hole 45 may be formed between the lowest end of the partition wall 40 and the opening 43. In this 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. As a result, the oil circulation structure 1 of the present invention can further reduce the resistance to stirring the oil. In addition, backflow of oil due to the proximity of the communication hole 45 and the oil intake port 37 can also be suppressed. 【0067】 Furthermore, the communication holes 45 can be formed at various positions, taking into consideration the rotational resistance and bubble rate of the pulley, or the suppression of backflow of oil from the oil pan 35. The shape and size of the communication holes 45 can also be appropriately changed according to the characteristics of the oil, the shape and size of the transmission 2, etc. The openings 43 can also be formed at various positions according to the characteristics of the oil, the shape of the transmission 2, etc. Moreover, the communication holes 45 may be formed in multiple locations, not just a single one. 【0068】 In this embodiment, the primary pulley 15 is shown as being positioned on the lower side in the vertical direction, but the primary pulley 15 and the secondary pulley 25 may be positioned upside down. Also, in this embodiment, a steel belt 30 is shown as the endless belt 30, but belts of various materials can be used for the endless belt 30. Furthermore, in this embodiment, the axes of the primary pulley 15 and the secondary pulley 25 are shown as being offset in the vertical direction, but the amount of offset can be appropriately changed depending on the shape and size of the transmission 2, or the position where the oil pan 35 is located. 【0069】 The partition wall 40 is not limited to those that are curved or bent in a convex shape toward downward, or those that are formed in a curved shape along the circumferential direction of the pulley; various shapes and sizes can be used. In this embodiment, the partition wall 40 is formed to surround the primary pulley 15, but the partition wall 40 may be formed to surround at least a part of the secondary pulley 25 together with the primary pulley 15. 【0070】 In this embodiment, a strainer 36 is arranged inside the oil pan 35, and a communication hole 45 is shown to be 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. Furthermore, the strainer 36 may be provided only as needed, and a configuration without a strainer 36 is also possible. In addition, although the strainer 36 is arranged inside the oil pan 35 in this embodiment, the strainer 36 can be placed in various positions. For example, the strainer 36 can be placed above the oil pan 35 or outside the oil pan 35. 【0071】 Furthermore, the first oil circulation structure 1A of the present invention can be suitably adopted in various types of CVTs. Note that the oil circulation structure 1 of the present invention is not limited to vertically mounted CVTs, but may also be adopted in horizontally mounted CVTs. Also, although a belt-type CVT was exemplified in this embodiment, the oil circulation structure 1 of the present invention may be used not only in belt-type CVTs, but also in, for example, chain-type or toroidal-type CVTs. 【0072】 The case 3 housing the transmission unit 2A can be made of various shapes and sizes to match the shape and size of the transmission unit 2A. Similarly, the shape and size of the oil pan 35 and strainer 36 can be made of various shapes and sizes to match the configuration of the transmission 2. The positions of the oil pan 35 and strainer 36 can also be changed as appropriate. Furthermore, the outlet hole 3B of the case 3 and the suction port 37 of the strainer 36 can be made of various shapes and sizes. The partition 50 can also be made of various shapes and sizes, as long as it can form a bypass 51. For example, partitions 50 that are not bent or those formed from thick ridges rather than plate-like members can be used. The distance of the bypass 51 formed by the partition 50 can be changed as appropriate depending on the characteristics of the oil and the structure of the transmission 2. The partition 50 can also be provided in various forms, such as being integrally formed with the oil pan 35 or being formed separately from the oil pan 35. Furthermore, the outflow port 3B and the suction port 37 may be formed in multiple locations, rather than being a single one. 【0073】 In this embodiment, an example is shown in which the magnet member 52 is arranged along the path of the bypass circuit 51. However, the oil circulation structure 1 of the present invention is not limited to this, and the magnet member 52 can be arranged at various positions. Furthermore, the magnet member 52 is not limited to being formed as a drain bolt, but can be of various forms. In addition, there may be more than one magnet member 52, and the structure may also be configured without any magnet member 52. 【0074】 In this embodiment, the valve body 60 is positioned above the oil pan 35 as an example, but the valve body 60 can be positioned in various locations. Also, in this embodiment, the partition 50 is formed extending from the lower end of the valve body 60 to the bottom of the oil pan 35 as an example, but the location, size, or shape of the partition can be appropriately changed depending on the manner in which deformation of the oil pan 35 is suppressed. Furthermore, the second oil circulation structure 1B of the present invention is not limited to CVTs and can be used in various types of transmissions. 【0075】 Furthermore, although this embodiment illustrates a configuration that employs both the first oil circulation structure 1A and the second oil circulation structure 1B, it is also possible to adopt a configuration that employs only one of the first oil circulation structure 1A or the second oil circulation structure 1B. 【0076】 The above describes various embodiments and modifications of the oil circulation structure according to the present invention. However, the present invention is not limited to those exemplified in the embodiments and modifications described above, and it will be readily apparent to those skilled in the art that other embodiments may exist in the spirit and teachings thereof, without departing from the scope of the claims. [Industrial applicability] 【0077】 The oil circulation structure of the present invention can be used in various transmissions of vehicles and the like, and is particularly suitable for use in CVTs (continuously variable transmissions). [Explanation of Symbols] 【0078】 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 section 51: Detour 52: Magnetic component

Claims

[Claim 1] An oil circulation structure for a transmission mounted in a vehicle, A primary pulley that is rotated in response to power input from a drive source, A secondary pulley that outputs the shifted power, An endless belt stretched over the primary pulley and the secondary pulley, An oil pan is located at the lower end of the transmission and stores the oil filled in the transmission, The oil pan has a strainer with an intake port for drawing in the oil, The primary pulley and the secondary pulley are positioned with their respective axes offset to one side and the other side in the vertical direction. The device has a partition wall separating a pulley arrangement region where the primary pulley or the pulley positioned relatively lower among the secondary pulleys is arranged from a region below the pulley arrangement region. The partition wall is capable of storing at least a portion of the oil on the pulley arrangement side, and has a communication hole formed therein that opens to allow the oil to flow out toward the oil pan. An oil circulation structure characterized in that the oil pan is provided with a partition between the communication hole and the suction port. [Claim 2] The oil circulation structure according to claim 1, characterized in that the partition wall is curved or bent in a convex shape toward downward. [Claim 3] The partition wall has an opening formed therein that opens toward the rotational direction of the primary pulley or the secondary pulley, which is positioned relatively downward. The oil circulation structure according to claim 1 or 2, characterized in that the communication hole is formed between the lowest end of the partition wall and the opening.

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