JP7762079B2 - Oil circulation structure - Google Patents

Description

The present invention relates to an oil circulation structure for a transmission.

Conventionally, CVTs (Continuously Variable Transmissions) have been used as transmissions in 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 within the 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 fluid and lubricant.

Furthermore, a strainer that filters the oil is provided below the CVT described in Patent Document 1. The oil passes through the valve body and is used to operate and lubricate the primary pulley, secondary pulley, steel belt, etc., before being returned to the oil pan.

Japanese Patent Application Laid-Open No. 2021-25553

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

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

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.

In addition, the oil pump in a CVT is generally driven by engine power, and when the engine is in low rotation, such as in N range (neutral range) or P range (parking range), the pump rotation speed decreases and the oil circulation flow rate drops. As a result, oil with a high bubble content accumulates and collects around the strainer's suction port, and the collected bubbles are intermittently sucked up by the oil pump. For this reason, conventional CVTs are concerned about abnormal noise and reduced oil pressure. Furthermore, the supply of oil with a high bubble content raises concerns that oil supply shortages may become even more likely.

The present invention aims to provide an oil circulation structure for a transmission that can optimize the oil circulation flow rate by suppressing the circulation of oil containing air.

(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, and comprises: a case that houses a gear change unit in the transmission; an oil pan disposed below the case; and a strainer disposed in the oil pan. The strainer has an intake port that draws up oil stored in the oil pan; 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.

The oil circulation structure described above has a partition between the outflow hole opened in the case that houses the transmission unit and the suction port of the strainer. This partition forms a detour that diverts oil flowing out of the outflow hole and leads it to the suction port. Therefore, when oil with a high bubble content flows out of the outflow hole, the bubbles are separated as it passes through the detour. This allows the oil circulation structure described above to circulate oil with a low bubble content, thereby maintaining appropriate oil pressure and preventing gear shifting problems in the transmission. Furthermore, the oil circulation structure described above can reduce the bubble content of the oil drawn into the suction port of the strainer, which is expected to help reduce noise when the oil pump draws up oil.

In a transmission that uses the oil circulation structure described above, iron particles and other contaminants can become mixed into the oil due to wear and burrs on the various parts to which the oil is supplied (e.g., gears, pulleys, steel belts, etc.). If oil containing such iron particles is supplied to various parts, there is a concern that it could clog the hydraulic circuit in the valve body or get caught in various parts. This could result in poor gear shifting in the transmission or damage to the transmission itself.

(2) Therefore, to solve this problem, the oil circulation structure of the present invention described above may preferably include a magnetic member disposed along the route of the detour.

The above-described oil circulation structure, by being configured in this way, 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 preventing 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 configuring the above-described oil circulation structure in this way, metal particles attracted to the magnet member can be easily discharged, for example, during an oil change. 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.

However, when a vehicle is driven on rough roads (roads with many bumps), there is a risk that the transmission's oil pan may come into contact with stones or protrusions on the road, causing the oil pan to become deformed. Furthermore, if the oil pan becomes deformed, oil may not be supplied properly, which could cause the transmission to become inoperable.

(3) Therefore, in order to solve this problem, in the oil circulation structure of the present invention described above, a valve body that forms a hydraulic circuit is disposed 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.

The above-described oil circulation structure, by being configured in this way, can suppress deformation of the oil pan, for example, when the bottom of the oil pan receives an impact. In other words, the above-described oil circulation structure is designed so that when the bottom of the oil pan receives an impact, the partition portion braces itself between the bottom of the oil pan and the valve body. This allows the above-described oil circulation structure to operate the transmission stably. It is also expected that the oil pan protector used to suppress deformation of the oil pan can be simplified or even eliminated, which is expected to contribute to reducing the vehicle's weight.

(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 power input 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.

By configuring the oil circulation structure described above, it can be made suitable for continuously variable transmissions (CVTs). As a result, the oil circulation structure described above can prevent oil containing a lot of air (oil with a high air bubble content) from being sucked into the strainer's suction port. As a result, the oil circulation structure described above can prevent the circulation of oil with a high air bubble content, thereby reducing shifting problems and abnormal noise.

The present invention provides an oil circulation structure for a transmission that can optimize the oil circulation flow rate by suppressing the circulation of oil containing air.

1 is a cross-sectional view of a continuously variable transmission employing an oil circulation structure of the present invention, as viewed from above; 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; FIG. 2 is a bottom view of the oil circulation structure of the present invention with the oil pan removed. 3 is a cross-sectional view taken along the line AA in FIG. 2.

An oil circulation structure 1 according to an embodiment of the present invention will now be described with reference to Figures 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) as a transmission 2. The continuously variable transmission 2 will be described as being connected to an engine (not shown) as a drive source. Please note that oil is omitted from the drawings.

To explain the oil circulation structure 1, we will first provide a detailed description of the continuously variable transmission 2, which forms part of the oil circulation structure 1.

Figure 1 is a cross-sectional view of the continuously variable transmission 2 as seen from above. Figure 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 of the vehicle. Figure 3 is a bottom view of the continuously variable transmission 2 as seen from the bottom with the oil pan 35 removed. Please note that the primary shaft 10 is omitted from Figure 2.

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 it. 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 arranged 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 over 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 other components 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.

As shown in Figures 1 and 2, the case 3 is formed as the main body frame of the continuously variable transmission 2 and is cylindrically shaped so that it can accommodate 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. 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 a portion of oil (also known as lubricating oil, including fluid) inside.

The primary shaft 10 (see Figure 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 positioned so that its axis is located at 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.

As shown in FIG. 1, the primary pulley 15 has 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 between them. In this embodiment, the primary moving sheave 16 is arranged on the front side of the vehicle (the far 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.

The primary moving 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 driven to rotate with the input of power from the engine, and this in turn drives the primary pulley 15 to rotate. The primary moving sheave 16 can also be moved in the axial direction of the primary shaft 10 by the primary piston 18.

The primary piston 18 can also move the primary moving sheave 16 toward and 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. This allows the power input to the primary shaft 10 to be transmitted to the steel belt 30.

The secondary shaft 20 is arranged 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 arranged with their respective axes (primary shaft 10 and secondary shaft 20) offset to one side (upper side) and the other side (lower side) in the vertical direction.

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 secondary fixed sheave 27 are arranged to face each other via a steel belt 30. In this embodiment, the secondary fixed sheave 27 is arranged on the front side of the vehicle (rear side in the figure), and the secondary moving sheave 26 is arranged on the rear side of the vehicle (near side in the figure). In other words, the secondary moving sheave 26 and secondary fixed sheave 27 are arranged in the reverse order of front to back with respect to the primary moving sheave 16 and primary fixed sheave 17. Furthermore, the opposing surfaces of the secondary moving sheave 26 and secondary fixed sheave 27 are formed in a conical shape.

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 driven to rotate, and this in turn drives the secondary pulley 25 to rotate. In addition, the secondary movable sheave 26 can be moved in the axial direction of the secondary shaft 20 by the secondary piston 28.

The secondary piston 28 can also move the secondary movable sheave 26 toward and away from the secondary fixed sheave 27. A steel belt 30 is arranged 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 sandwiched and held between the secondary movable 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.

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 across 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.

As shown in Figure 4, the oil pan 35 is located in the lower end area of the continuously variable transmission 2. The oil pan 35 can store oil (also called fluid) filled in 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 appropriate seals (not shown).

As shown in Figure 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.

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 various parts.

In this embodiment, an oil injection nozzle 31 (see Figure 1) is provided in the area between the primary pulley 15 and the secondary pulley 25, 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.

The above describes the configuration of the continuously variable transmission 2. Next, we will explain in detail the oil circulation structure 1 according to one embodiment of the present invention. The oil circulation structure 1 is formed separately 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 opens into a partition wall 40 provided circumferentially outward 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 allow oil to detour. Below, the oil circulation structure 1A and the oil circulation structure 1B will be explained in detail in order.

<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.

The partition 40 is curved downward in a convex shape. In this embodiment, the partition 40 is curved to follow the circumferential direction of the primary pulley 15. As described above, the partition 40 serves as a partition wall separating the pulley arrangement area 41 from the oil pan 35, which is the 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 pulley arrangement area 41 side of the partition 40 (also simply referred to as above the partition 40) stores a portion of the oil delivered from the valve body 60 and the oil injected from the injection nozzle 31. As a result, a portion of the lower side of the primary pulley 15 is immersed in oil.

The partition wall 40 also has an opening 43 that opens toward the rotational direction of the primary pulley 15. The opening 43 faces the secondary pulley 25, which is located above it. The opening 43 allows oil that has accumulated on the partition wall 40 to overflow from its open end. The overflowing oil flows through an appropriate passage (in this embodiment, the outflow hole 3B, described below) 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 the fuel efficiency of the vehicle.

In addition, a communication hole 45 is formed at the lower end of the partition wall 40, allowing 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 (axial direction of the primary pulley 15).

In this embodiment, the communication hole 45 is connected to 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 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 is connected to the suction port 37 via a bypass path 51 formed by the partition 50. The communication hole 45 can be directly connected to the suction port 37 of the strainer 36, rather than indirectly connected via the bypass path 51 as in this embodiment. The diameter of the communication hole 45 can vary depending on the characteristics of the oil used, the amount of oil supplied, and the required discharge rate. The oil agitation resistance of the pulley can also be taken into consideration.

The oil that has accumulated on the partition wall 40 becomes cloudy and generates bubbles due to air being mixed in with it as a result of 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 large amount of air accumulates in the upper layer near the liquid surface (near the two-dot chain line in Figure 2). Furthermore, because air in oil is light and tends to rise, the oil in the upper layer has an even higher air bubble rate.

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 has a low air content (low air bubble content) that is separated from the liquid surface through the communication holes 45 to the strainer 36 (oil pan 35). Furthermore, because the oil circulation structure 1A is capable of circulating oil with a low air bubble content, it is possible to maintain appropriate oil 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.

In addition, the oil circulation structure 1A of the present invention returns oil that has accumulated on the partition wall 40 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 getting into the oil pump, and is expected to suppress abnormal noise when the oil pump sucks up oil. Furthermore, since the amount of oil filled into the transmission 2 can be reduced, it is expected that the cost of the transmission 2 can be reduced.

In addition, 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 in the vertical direction, so only the pulley on one side (in this embodiment, the primary pulley 15) is immersed in oil. This allows the oil circulation structure 1A of the present invention to reduce oil agitation resistance caused by the pulleys, which is expected to improve fuel efficiency in the vehicle. Furthermore, the partition 40 separates the pulley placement area 41 from the area below the pulley placement area 41, which separates the primary pulley 15 from the oil in the oil pan 35. This allows the oil circulation structure 1A of the present invention to reduce oil agitation resistance, which is expected to improve fuel efficiency in the vehicle.

In addition, 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 content toward the suction port 37 of the strainer 36, thereby preventing a shortage of oil being sucked up by the strainer 36. As a result, the oil circulation structure 1A of the present invention can prevent 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, abnormal noises when the oil pump crushes bubbles and when the oil pump sucks oil up into the strainer 36 can also be suppressed.

In addition, 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 oil agitation resistance at the pulley. This is expected to improve vehicle fuel efficiency. 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 high-porosity oil that has accumulated in the upper layer (liquid surface side) from the low-porosity oil in the lower layer. Furthermore, the low-porosity oil 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 appropriate oil pressure and preventing shifting problems in the transmission 2.

The partition wall 40 need not necessarily be curved along the circumferential direction of the primary pulley 15; it may also be curved or bent in a downward convex shape. By forming the partition wall 40 in this downward convex shape, oil with a low air bubble content that accumulates on the partition wall 40 can be collected downward, as in the above-described embodiment. The degree of curvature or bending can be changed as appropriate, but should be within a range that does not increase the rotational resistance of the primary pulley 15 too much.

As described above, the oil circulation structure 1A of the present invention can suppress the circulation of oil with a high air bubble content, making it possible to optimize the oil circulation flow rate. As a result, the oil circulation structure 1A of the present invention can maintain appropriate oil pressure and prevent transmission shifting problems. Furthermore, the oil circulation structure 1A of the present invention can suppress air entrapment in the oil pump, thereby also preventing abnormal oil pump noise.

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.

<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.

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.

Figure 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 from a plate-shaped member, with its middle portion bent into an L-shape. The partition 50 extends from the lower end (underside) 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. 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 severe bumps and depressions), thereby enabling stable operation of the transmission 2. It is also expected that the oil pan protector used to prevent deformation of the oil pan 35 can be simplified or even eliminated, which is expected to contribute to reducing the vehicle's weight.

The partition 50 also forms a bypass 51 that diverts oil flowing out of the outlet 3B and directs it toward the suction port 37. In other words, the oil flowing out of the outlet 3B is not directly drawn into the suction port 37, but travels a certain distance through the bypass 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 flowing out of the outlet 3B as it passes through the bypass 51. This allows the oil circulation structure 1B of the present invention to circulate oil with a low air bubble content, thereby maintaining 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 suppressing noise generated when air bubbles are crushed by the strainer 36. This is also expected to suppress noise generated when an oil pump (not shown) draws up oil. The length of the detour 51 formed by the partition 50 can be changed as appropriate depending on the oil characteristics and the configuration of the transmission 2.

A magnet member 52 is also provided on the route of the detour 51. The magnet member 52 is designed to remove foreign matter, such as iron powder, that gets 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 prevent gear shifting problems in the transmission 2 due to foreign matter getting caught in the oil. Furthermore, the oil circulation structure 1B of the present invention can also use the magnet member 52 as a drain bolt, making 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 reduced, which is expected to lead to a more compact transmission 2.

The above is an embodiment 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-described embodiment and can be modified in various ways.

In this embodiment, the communication hole 45 is formed at the bottom end of the partition wall 40. However, for example, the communication hole 45 may be formed between the bottom end of the partition wall 40 and the opening 43. In such a case, oil is discharged from the communication hole 45 in response to 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 oil stirring resistance. It also prevents backflow of oil due to the communication hole 45 being close to the oil suction port 37.

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 to suit the oil characteristics and the shape and size of the transmission 2. The opening 43 can be formed in various positions to suit the oil characteristics and the shape of the transmission 2. There can be multiple communication holes 45, not just one.

In this embodiment, the primary pulley 15 is disposed on the lower side in the vertical direction, but the primary pulley 15 and secondary pulley 25 may be disposed upside down. Furthermore, in this embodiment, a steel belt 30 is used as the endless belt 30, but belts made of various materials can be used for the endless belt 30. Furthermore, in this embodiment, the axes of the primary pulley 15 and secondary pulley 25 are 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.

The partition wall 40 can be curved or bent downward in a convex shape, or curved along the circumferential direction of the pulley, and various other 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 also be formed to surround at least a portion of the secondary pulley 25 together with the primary pulley 15.

In this 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 this 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.

The first oil circulation structure 1A of the present invention can be preferably adopted in various types of CVTs. 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. Furthermore, while a belt-type CVT is 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 chain-type or toroidal-type CVTs, for example.

The case 3 housing the transmission unit 2A can be of various shapes and sizes to accommodate the shape and size of the transmission unit 2A. The oil pan 35 and strainer 36 can be of various shapes and sizes to accommodate the configuration of the transmission 2. The locations 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 of various shapes and sizes. The partition 50 can be of various shapes and sizes as long as it can form the bypass 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 bypass 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 configurations, such as being integral with the oil pan 35 or being separate from the oil pan 35. Additionally, the outlet hole 3B and the suction port 37 may be formed in multiple locations rather than just one.

In this embodiment, the magnet member 52 is disposed along 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 multiple numbers, not just one, and the configuration may also be one without a magnet member 52.

In this embodiment, the valve body 60 is disposed above the oil pan 35, but the valve body 60 can be disposed in various positions. Furthermore, in this embodiment, the partition 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 can be changed as appropriate 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 transmissions.

In addition, although this embodiment illustrates an example in which both the first oil circulation structure 1A and the second oil circulation structure 1B are employed, it is also possible to employ a configuration in which only one of the first oil circulation structure 1A and the second oil circulation structure 1B is employed.

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. Those skilled in the art will readily understand that other embodiments are possible within the scope of the claims and in keeping with the teachings and spirit of the invention.

The oil circulation structure of the present invention can be used in various transmissions for vehicles, etc., and is particularly suitable for use in CVTs (continuously variable transmissions).

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: Outlet hole 15: Primary pulley 25: Secondary pulley 30: Steel belt (endless belt)
35: Oil pan 36: Strainer 37: Intake port 40: Partition wall 41: Pulley arrangement area 43: Opening 45: Communication hole 50: Partition portion 51: Detour 52: Magnet member

Claims (2)

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 . 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.