JP7520459B2 - Lock-up clutches and torque converters - Google Patents

Description

The present invention relates to a lock-up clutch and a torque converter.

The lock-up clutch is a mechanism that hydraulically drives a piston, located inside the torque converter housing, to fasten it to the front cover of the torque converter. The piston is connected to the turbine runner of the torque converter, and the front cover is connected to a crankshaft (not shown) to which the rotational driving force of the engine is input. Fastening the piston to the front cover directly connects the crankshaft and turbine runner.

The surface of the piston that faces the front cover is provided with a facing material, which is an annular friction material. When the piston is fastened to the front cover, this facing material comes into contact with the front cover.

In a lock-up clutch, the facing material slips against the front cover before the piston and front cover are fully engaged. Frictional heat is generated when the facing material slips. If the temperature of the oil in the housing rises due to frictional heat, this can affect the durability of the oil. Patent Document 1 proposes providing grooves in the facing material and circulating the oil through these grooves in a slipping state to suppress the rise in oil temperature.

Japanese Patent Application Publication No. 5-272615

However, if grooves are provided in the facing material, there is a possibility that the corners of the grooves may peel off when the facing material comes into contact with the front cover. Furthermore, the contact area between the facing material and the front cover is reduced by the amount of the grooves provided. This reduction in contact area may increase the surface pressure acting on the part of the facing material that comes into contact with the front cover, making the facing material more susceptible to wear. Furthermore, because oil does not flow through parts of the facing material where grooves are not formed, it is possible to reduce the average temperature of the entire facing material, but it is difficult to suppress localized heat generation.

In lock-up clutches and torque converters equipped with lock-up clutches, there is a need to reduce heat generation while reducing wear on the facing material.

According to one aspect of the present invention, the lock-up clutch includes:
A torque converter has a front cover that rotates around an axis, and a turbine runner that is provided on the axis. The torque converter has a front cover that rotates around an axis, and the front cover and the turbine runner are connected to the axis. The torque converter has a front cover that rotates around an axis. The ...
a piston connected to the turbine runner and driven in the axial direction by hydraulic pressure to come into contact with and move away from the front cover;
When one of the opposing surfaces of the front cover and the piston is defined as a first surface and the other is defined as a second surface, an annular friction material is provided on the first surface;
an annular region provided on the second surface and facing the annular friction material;
The annular region is provided with a mesh-like oil groove formed of a plurality of continuous grooves ,
an oil passage through which oil flows is provided between the piston and the front cover;
the piston is connected to the turbine runner at an inner diameter side in the axial direction, and is driven by the hydraulic pressure at an outer diameter side in the axial direction to come into contact with and move away from the front cover,
the annular region has an outer diameter side annular region that contacts the friction material in a slip state in which the piston contacts the front cover while slipping, and an inner diameter side annular region that is located on the inner diameter side of the outer diameter side annular region,
The mesh-like oil grooves are provided in the outer diameter side annular region, and are not provided in the inner diameter side annular region .

According to one aspect of the present invention, a torque converter includes:
A front cover that rotates around an axis;
a pump impeller that rotates integrally with the front cover;
a turbine runner provided on the axis and arranged opposite to the pump impeller;
a lock-up clutch that switches between fastening and releasing between the front cover and the turbine runner,
The lock-up clutch is
a piston connected to the turbine runner and driven in the axial direction by hydraulic pressure to come into contact with and move away from the front cover;
When one of the opposing surfaces of the front cover and the piston is defined as a first surface and the other is defined as a second surface, an annular friction material is provided on the first surface;
an annular region provided on the second surface and facing the annular friction material;
The annular region is provided with a mesh-like oil groove formed of a plurality of continuous grooves ,
an oil passage through which oil flows is provided between the piston and the front cover;
the piston is connected to the turbine runner at an inner diameter side in the axial direction, and is driven by the hydraulic pressure at an outer diameter side in the axial direction to come into contact with and move away from the front cover,
the annular region has an outer diameter side annular region that contacts the friction material in a slip state in which the piston contacts the front cover while slipping, and an inner diameter side annular region that is located on the inner diameter side of the outer diameter side annular region,
The mesh-like oil grooves are provided in the outer diameter side annular region, and are not provided in the inner diameter side annular region .

According to one aspect of the present invention, it is possible to reduce wear on the facing material, which is a friction material, while suppressing heat generation.

1 is a diagram showing a torque converter equipped with a lock-up clutch according to an embodiment; FIG. 2 is an enlarged view of area A in FIG. 11 is a diagram showing a part of the annular region of the front cover as viewed from the rotation axis direction. FIG. FIG. 4 is a diagram showing an embodiment of a hexagonal groove different from that shown in FIG. 3 . FIG. 13 is a diagram showing details of a hexagonal groove. FIG. 13 is a diagram showing the actuation of the piston. FIG. 4 is a diagram showing a slip state of the lock-up clutch. FIG. 4 is a diagram showing a lockup state of the lockup clutch. FIG. 13 is a diagram showing a comparative example 1 in which grooves are formed in a facing material. FIG. 11 is a diagram showing a comparative example 2 in which oil grooves are formed over the entire annular region. FIG. 11 is a diagram showing a configuration of an oil groove according to Modification 1. FIG. 11 is a diagram showing a configuration of an oil groove according to Modification 2.

Below, a lock-up clutch according to an embodiment of the present invention will be described with reference to the drawings. In the embodiment, an example of a lock-up clutch provided in a torque converter will be described.

A torque converter is a fluid transmission device that is installed in a vehicle equipped with a drive source. In the embodiment, an example in which the drive source is an engine is described. The torque converter transmits the rotational drive force of the engine to the transmission.

FIG. 1 is a diagram showing a torque converter equipped with a lock-up clutch according to an embodiment of the present invention.
FIG. 2 is an enlarged view of area A in FIG.
1, the torque converter 1 includes a pump impeller 3, a turbine runner 5, and a stator 6, which are arranged in a converter housing 2. The converter housing 2 is composed of a pump shell 30 of the pump impeller 3, and a front cover 4. An oil chamber OR is formed in the converter housing 2, to which oil, which is a working fluid, is supplied.

The pump impeller 3 and the turbine runner 5 are arranged so as to be capable of relative rotation on a common axis, the rotation axis X. A plurality of blades 31, 51 are fixed to the opposing surfaces of the pump impeller 3 and the turbine runner 5, respectively. The plurality of blades 31, 51 are each arranged radially when viewed from the axial direction of the rotation axis X.

In the following explanation, the "axial direction of the rotation axis X" will simply be referred to as the "direction of the rotation axis X." In the following explanation, the "inner diameter side in the radial direction of the rotation axis X" and the "outer diameter side in the radial direction of the rotation axis X" will also simply be referred to as the "inner diameter side" and the "outer diameter side."

The stator 6 is located between the pump impeller 3 and the turbine runner 5 .
The stator 6 is supported by a stator shaft 61 via a one-way clutch OWC. The stator 6 is capable of rotating only in one circumferential direction about the rotation axis X. The stator shaft 61 is fixed to a transmission case (not shown).

The front cover 4 is connected to a crankshaft of an engine (not shown). The turbine runner 5 is fixed to a turbine hub 7 located on the inner diameter side.
The turbine hub 7 has a flange-shaped connecting portion 72 and a cylindrical base portion 71. The turbine runner 5 is fixed to the connecting portion 72 with a rivet R. The base portion 71 is attached by spline fitting to the outer periphery of the input shaft IS.

The rotational driving force of the engine is input to the front cover 4 from a crankshaft (not shown). A pump shell 30 of the pump impeller 3 is fixed to the front cover 4. Therefore, the rotational driving force input to the front cover 4 is input to the pump impeller 3. The rotational driving force input to the pump impeller 3 is transmitted to the turbine runner 5 via the oil in the converter housing 2. The rotational driving force of the engine transmitted to the turbine runner 5 is transmitted to the transmission via the turbine hub 7 and the input shaft IS.

The torque converter 1 has a lock-up clutch 8 that connects the front cover 4 and the turbine runner 5 so that they cannot rotate relative to each other. When the front cover 4 and the turbine runner 5 are connected so that they cannot rotate relative to each other, the rotational driving force of the engine is input directly from the front cover 4 to the turbine runner 5.

The lock-up clutch 8 is disposed between the turbine runner 5 and the front cover 4 inside the converter housing 2. The lock-up clutch 8 includes a piston 80 that fastens to the front cover 4, and a torsion damper 90. The torsion damper 90 absorbs vibrations caused by the input rotational driving force of the engine when the piston 80 fastens to the front cover 4.

The piston 80 is a disk-shaped member arranged on the rotation axis X. The piston 80 has a cylindrical portion 81 located on the inner diameter side in the direction of the rotation axis X, and a disk portion 83 and a flange portion 89 located on the outer diameter side.

The cylindrical portion 81 of the piston 80 is fitted onto the base portion 71 of the turbine hub 7. One end 81a of the cylindrical portion 81 abuts against the connecting portion 72 of the turbine hub 7. The other end 81b of the cylindrical portion 81 is connected to the disk portion 83.

The disk portion 83 and the flange portion 89 have shapes corresponding to the front cover 4 .
The front cover 4 includes a disk-shaped side wall portion 41 extending radially about the rotation axis X, and a peripheral wall portion 49 bent at the outer edge of the side wall portion 41 in the direction of the rotation axis X and joined to the pump shell 30 .

The disk portion 83 extends from the other end 81b of the tube portion 81 in the radial direction of the rotation axis X along the side wall portion 41 of the front cover 4. The flange portion 89 bends from the outer edge of the disk portion 83 in the direction of the rotation axis X and extends along the peripheral wall portion 49 of the front cover 4.

The disk portion 83 and the flange portion 89 are disposed with a gap between them and the side wall portion 41 and the peripheral wall portion 49, respectively. This gap forms an oil passage OP3 that allows oil to flow between the piston 80 and the front cover 4.

The oil passage OP3 communicates with an oil chamber OR formed in the converter housing 2. The oil passage OP3 also communicates with an oil passage OP1 provided in the input shaft IS. The oil chamber OR communicates with an oil passage OP2 formed between the inner wall of the converter sleeve 32 extending from the pump impeller 3 and the outer wall of the stator shaft 61.

The oil passages OP1 and OP2 are connected to a hydraulic control device 100. The hydraulic control device 100 controls the hydraulic pressure supplied to the oil passage OP3 and the oil chamber OR. The piston 80 is driven in the direction of the rotation axis X by the difference in hydraulic pressure supplied to the oil passage OP3 and the oil chamber OR, the details of which will be described later.

One end of the torsion damper 90 is fixed to the surface 84 of the disk portion 83 facing the turbine runner 5 via a rivet R. The other end of the torsion damper 90 is fixed to the connecting portion 72 of the turbine hub 7 via a rivet R.

A facing material 86 is fixed to the surface 85 (first surface) of the disk portion 83 on the front cover 4 side. The facing material 86 is annular and is arranged in the circumferential direction of the rotation axis X at a position near the outer edge of the disk portion 83. The facing material 86 is a friction material composed of, for example, fibers impregnated with synthetic resin or the like.

As shown in FIG. 2, the facing material 86 protrudes from the surface 85 of the disk portion 83 toward the side wall portion 41 of the front cover 4. The facing material 86 is located in an oil passage OP3 formed between the surface 85 and the surface 42 (second surface) of the side wall portion 41 of the front cover 4.

The front cover 4 has an annular region 43 on the surface 42 that faces the facing material 86 in the direction of the rotation axis X.

FIG. 3 is a diagram showing a part of the annular region 43 of the front cover 4 as viewed from the direction of the rotation axis X. As shown in FIG.
3, the annular region 43 is divided into two annular regions 43, a radially inner region 44 (inner diameter side annular region) and a radially outer region 45 (outer diameter side annular region) centered on the rotation axis X. As shown in FIG. 2, the region 44 faces an inner diameter side region 87 of the facing material 86, and the region 45 faces an outer diameter side region 88 of the facing material 86.

Region 45 is a portion that comes into contact with region 88 (see FIG. 2) of facing material 86 when lock-up clutch 8 is in a slipping state, which will be described later. Region 44 is a portion that is separated from region 87 when lock-up clutch 8 is in a slipping state, which will be described later, and that comes into contact with region 87 when lock-up clutch 8 is in a lock-up state, which will be described later.
In the drawings, the radial lengths of the regions 44 and 45 are shown to be the same for convenience, but are not limited to this. The radial lengths of the regions 44 and 45 can be set appropriately depending on the contact state between the facing material 86 and the annular region 43 in the slip state and the lock-up state.

As shown in FIG. 3, area 44 is a flat surface, but area 45 has a mesh-like oil groove 46. In FIG. 3, the oil groove 46 is shown diagrammatically with hatching, and the circled area is shown enlarged.

The oil groove 46 is composed of continuous fine hexagonal grooves 460. The hexagonal grooves 460 are spread throughout the entire region 45 without any gaps.

The hexagonal groove 460 can be formed by a known method. For example, when forming the hexagonal groove 460 by laser processing, the groove width GW of the hexagonal groove 460 may be set to gradually increase from the inner diameter side to the outer diameter side of the rotation axis X in order to ensure that the hexagonal groove 460 is spread throughout the annular region 45 without any gaps.

FIG. 4 is a diagram showing an embodiment of a hexagonal groove 460 different from that shown in FIG.
4 shows an example of a hexagonal groove 460 suitable for press working. In FIG. 4, the groove width of the hexagonal groove 460 is constant, but the size of the hexagon is adjusted. The size of the hexagon means the area of the flat surface portion surrounded by the hexagonal groove 460. Specifically, the size of the hexagon can be adjusted so as to increase from the inner diameter side to the outer diameter side of the rotation axis X. In this case, the radial width RW of the hexagon may be constant, and the circumferential width CW of the flat surface portion may be increased from the inner diameter side to the outer diameter side, thereby increasing the size of the hexagon.

FIG. 5 shows the hexagonal groove 460 in greater detail.
In Fig. 5, the continuous hexagonal grooves 460 are shown to be of the same size. Here, the structure of the hexagonal groove 460A shown in bold in the center of Fig. 6 will be described as an example. The hexagonal groove 460A has six grooves 461a to 461c and six corners 462.

The six grooves 461a to 461c extend in different directions and connect to adjacent grooves at corners 462. The six grooves 461a to 461c have the same length, and the distances from the center O of the hexagonal groove 460A to the six corners 462 are equal. The center O is the intersection of the diagonals connecting each corner 462, and is located on the surface of the front cover 4.

In FIG. 5, the hexagonal groove 460A is illustrated as a regular hexagon, but it does not have to be a regular hexagon in the strict sense, and dimensional error is permitted. Also, as in FIG. 3 and FIG. 4, when the size is adjusted from the inner diameter side to the outer diameter side, some of the hexagonal grooves 460 may be regular hexagonal and some may not be regular hexagonal.

The hexagonal groove 460A extends along the circumferential direction of the rotation axis X and has a pair of circumferential grooves 461a, 461a adjacent to each other in the radial direction of the rotation axis X. The ends of one side (left side in the figure) of the pair of circumferential grooves 461a, 461a and the ends of the other side (right side in the figure) are connected by radial grooves 461b, 461c that extend in a zigzag pattern with respect to a line segment parallel to the radial direction.

In this way, the hexagonal groove 460A forms a single groove in which grooves extending in different directions are connected by connecting the ends of the circumferential grooves 461a, 461a and the radial grooves 461b, 461c.

The hexagonal groove 460A is adjacent to six other hexagonal grooves 460 in the radial and circumferential directions. The hexagonal groove 460A shares a circumferential groove 461a with the hexagonal groove 460 adjacent to it in the radial direction. The hexagonal groove 460A shares either a radial groove 461b or a radial groove 461c with the hexagonal groove 460 adjacent to it in the circumferential direction.

The hexagonal groove 460A also shares a corner 462 with two radially or circumferentially adjacent hexagonal grooves 460. This allows all of the grooves that make up the hexagonal groove 460 to branch off and communicate with other grooves at the corner 462.

For example, circumferential groove 461a branches into radial grooves 461b and 461c at corner 462. When radial groove 461b reaches corner 462, it branches into radial groove 461c and circumferential groove 461a. Although not shown, radial groove 461c branches into radial groove 461b and circumferential groove 461a when it reaches corner 462.

The dimensions of each hexagonal groove 460 are not limited, but for example, the length of the circumferential groove 461a and the radial grooves 461b and 461c can each be 120 μm, the groove depth can be 20 μm, and the groove width can be 50 μm.

In region 45, minute hexagonal grooves 460 are continuously formed, resulting in a network of oil grooves 46 that are evenly distributed throughout.

Next, the operation of the lock-up clutch 8 will be described.
FIG. 6 is a diagram showing the actuation of the piston 80. As shown in FIG.
FIG. 7 is a diagram showing the lock-up clutch 8 in a slip state.
FIG. 8 is a diagram showing the lock-up state of the lock-up clutch 8.
FIG. 9 is a diagram showing a comparative example 1 in which a groove 860 is formed in a facing material 86. As shown in FIG.
FIG. 10 is a diagram showing a comparative example 2 in which an oil groove 490 is formed over the entire annular region 43. In FIG.
As described above, the oil groove 46 in the embodiment is composed of fine hexagonal grooves 460 (see FIG. 3 ). However, in FIGS. 7 and 8 , the oil groove 46 is illustrated in an exaggerated manner in order to make the function of the oil groove 46 easier to understand.

As described above, the piston 80 of the lock-up clutch 8 is driven in the direction of the rotation axis X by controlling the oil pressure supplied to the oil passage OP3 and the oil chamber OR. The lock-up clutch 8 is switched between a locked-up state and a released state by driving the piston 80. The locked-up state means that the piston 80 is completely fastened to the front cover 4 (see FIG. 8), and the released state means that the piston 80 is separated from the front cover 4 and is no longer fastened to the front cover 4 (see FIG. 2).

When the oil pressure in the oil passage OP3 and the oil chamber OR are equal, as shown in FIG. 2, the piston 80 moves away from the front cover 4 and the lock-up clutch 8 is released. At this time, the rotational driving force of the engine input to the front cover 4 is transmitted from the pump impeller 3 to the turbine runner 5 via the oil in the converter housing 2.

When the oil pressure in the oil chamber OR is increased and the oil pressure in the oil passage OP3 is decreased, a pressure difference occurs between the oil chamber OR and the oil passage OP3. This pressure difference exerts a force on the piston 80 pushing it toward the front cover 4 in the direction of the rotation axis X, as shown by the white arrow in FIG.
Here, the piston 80 is fixed to the turbine hub 7 on the inner diameter side (see FIG. 1), but the outer diameter side is free. Therefore, as shown in FIG. 6, the disk portion 83 of the piston 80 is displaced with the outer diameter side inclined toward the front cover 4 with respect to the inner diameter side.

As shown in FIG. 7, as the displacement of the piston 80 progresses, the facing material 86 protruding from the surface 85 toward the front cover 4 comes into contact with the annular region 43 of the opposing front cover 4. As described above, the outer diameter side of the piston 80 is inclined toward the front cover 4. Therefore, the outer diameter side region 88 of the facing material 86 comes into contact with the surface 42 of the front cover 4 before the inner diameter side region 87. In other words, only the outer diameter side region 88 comes into contact with the outer diameter side region 45 of the front cover 4, and the inner diameter side region 87 of the facing material 86 is separated from the inner diameter side region 44 of the front cover 4.

When the facing material 86 is not in full contact with the annular region 43, the facing material 86 is not pressed against the annular region 43, but is in a slipping contact state. Because the piston 80 rotates relative to the front cover 4, it is not in a completely fastened state. This state is called a slipping state.

When the pressure difference between the oil chamber OR and the oil passage OP3 is further increased, the force pressing the piston 80 toward the front cover 4 is further increased. As the force increases, the entire surface of the facing material 86 is pressed against the annular region 43 and pressed against it, as shown in FIG. 8. This stops the facing material 86 from slipping, and the piston 80 enters a locked-up state in which it is completely fastened to the front cover 4.

In the lock-up state, the piston 80 rotates integrally with the front cover 4, which is rotated by the rotational driving force of the engine. As shown in FIG.
In this state, the rotational driving force of the engine input to the front cover 4 is output directly to the input shaft IS without passing through the oil in the torque converter 1 .

To release the lockup, the oil pressure in the oil chamber OR is lowered and the oil pressure in the oil passage OP3 is increased. As the pressure difference decreases, the piston 80 is displaced away from the front cover 4, and the release state shown in Figure 2 is reached.

In the slip state shown in FIG. 7, frictional heat is generated between the facing material 86 and the annular region 43 of the front cover 4. If this frictional heat causes the oil temperature of the oil OL in the oil passage OP3 to rise, this may affect the durability of the oil OL.

Furthermore, the temperature rise of the oil OL affects the μV characteristics of the facing material 86 and the front cover 4, and may accelerate the deterioration of the lock-up clutch 8 over time. Note that the μV characteristics indicate the friction coefficient (μ) between the facing material 86 and the front cover 4 according to the relative speed (V) between them in a slipping state.

To suppress the temperature rise of the oil OL in the oil passage OP3, it is desirable to circulate the oil OL between the oil passage OP3 and the oil chamber OR. However, when the facing material 86 comes into contact with the annular region 43 and the oil passage OP3 is closed, the circulation of the oil OL is impeded.

As described above, in the slip state, only the outer diameter region 88 of the facing material 86 is in contact with the outer diameter region 45 of the front cover 4. A mesh-like oil groove 46 is formed in the outer diameter region 45 of the front cover 4.

The oil OL supplied to the oil passage OP3 can flow through the oil groove 46 at the point where the region 88 of the facing material 86 and the region 45 of the annular region 43 come into contact. Furthermore, because the region 87 of the facing material 86 and the region 44 of the annular region 43 are separated, the oil OL can also flow through this point. In this way, the oil passage OP3 communicates through the oil groove 46 formed in the region 45, so the oil OL can circulate even in a slip state. This reduces the rise in oil temperature due to frictional heat, and improves the durability of the oil OL.

The mesh-like oil grooves 46 are formed without gaps and are spread throughout the area 45. This allows the oil OL to spread throughout the entire area 45. The facing material 86 and the front cover 4 can be cooled by heat exchange with the oil OL that has spread throughout the area 45.

Furthermore, as shown in FIG. 5, the oil groove 46 formed in the region 45 is composed of continuous fine hexagonal grooves 460. Each hexagonal groove 460 communicates with the other hexagonal grooves 460 by sharing either the circumferential groove 461a or the radial grooves 461b, 461c. This enhances the fluidity of the oil OL that has entered the oil groove 46.

For example, when the oil OL flowing through the circumferential groove 461a and the radial groove 461b reaches the corner 462, it flows into the radial groove 461c on the outer diameter side. When the oil OL flowing through the radial groove 461b reaches the corner 462, it is pushed aside by the corner 462 and flows into the circumferential groove 461a and the radial groove 461c. In this way, the oil OL flowing through each groove merges at the corner 462, or is pushed aside by the corner 462 and branches, thereby increasing the fluidity of the oil OL.

By increasing the fluidity of the oil OL that has entered the oil groove 46, it becomes easier to discharge from the oil groove 46, and the circulation performance of the oil OL is also improved. In addition, because the oil OL enters the oil groove 46, excess oil OL is less likely to remain between the facing material 86 and the front cover 4, and the μV characteristics can also be improved.

Here, as shown in Comparative Example 1 of Figure 9, it is also possible to form an oil groove on the facing material 86 side. Unlike the front cover 4, which is a metal member, it is difficult to form fine hexagonal grooves 460 as in the embodiment in the facing material 86, which is made of nonwoven fabric. Therefore, when forming an oil groove in the facing material 86, it is possible to form multiple grooves 860 extending in the radial direction, for example, in a radial pattern.

However, in the case of Comparative Example 1, although the rise in oil temperature can be suppressed by circulating the oil OL in the oil passage OP3, the portion of the facing material 86 where the groove 860 is not formed is not cooled by the oil OL, making it difficult to suppress localized heat generation.

In addition, the corners of the grooves 860 formed in the facing material 86 may come into contact with the front cover 4 and peel off.

Furthermore, since the groove 860 in Comparative Example 1 has a larger area than the fine oil groove 46 in the embodiment, the contact area between the facing material 86 and the front cover 4 is reduced. In order to maintain the friction coefficient (μ) with the contact area reduced, it is necessary to increase the differential pressure between the oil chamber OR and the oil passage OP3 and increase the surface pressure on the facing material 86. Increasing the surface pressure on the facing material 86 may cause the facing material 86 to become more susceptible to wear.

Because the groove 860 formed in the facing material 86 is relatively large, a vortex may occur in the oil OL flowing inside the groove 860 just before the facing material 86 and the front cover 4 lock up, which may affect the control of the oil pressure difference between the oil chamber OR and the oil passage OP3.

In addition, the formation of the groove 860 reduces the rigidity of the facing material 86, which may affect the initial μV characteristics of the facing material 86 and the front cover 4.

On the other hand, in the embodiment, as shown in FIG. 4, the oil groove 46 is provided on the front cover 4 side.
Since the front cover 4 is a metal member having high rigidity, the mesh-like oil grooves 46 can be formed without gaps over the entire region 45 .
As a result, as described above, the oil OL is distributed throughout the oil grooves 46 formed in the entire region 45, making it possible to suppress localized heat generation.

In addition, the facing material 86 does not have corners in the grooves as in Comparative Example 1, so it is possible to prevent the corners from peeling off when they come into contact with the front cover 4.

The oil grooves 46 formed in the front cover 4 are made up of minute hexagonal grooves 460, which makes it possible to suppress a reduction in the contact area between the facing material 86 and the front cover 4. This makes it unnecessary to increase the surface pressure on the facing material 86 in order to maintain the coefficient of friction (μ) between the facing material 86 and the front cover 4, and makes it possible to suppress wear on the facing material 86.

The oil groove 46 in the embodiment is composed of fine hexagonal grooves 460. Therefore, it is possible to reduce the possibility of a vortex being generated in the groove 860 just before lockup between the facing material 86 and the front cover 4, as in Comparative Example 1. This reduces the impact on the control of the differential pressure between the oil chamber OR and the oil passage OP3.

Moreover, by not providing the grooves 860 in the facing material 86 as in Comparative Example 1, it is possible to prevent a decrease in the rigidity of the facing material 86. Therefore, it is possible to reduce the influence of the facing material 86 and the front cover 4 on the initial μV characteristics.
Furthermore, when the lock-up clutch 8 is in a slipping state, if there is an excessive amount of oil OL between the facing material 86 and the front cover 4, this may affect the initial μ-V characteristics of the facing material 86 and the front cover 4. In the embodiment, the excess oil OL enters the oil groove 46 of the front cover 4, thereby improving the initial μ-V characteristics.

The μ-V characteristics of the facing material 86 and front cover 4 are mainly affected by the porosity of the facing material 86, but in this embodiment, the oil grooves 46 formed in the front cover 4 also contribute to the μ-V characteristics. This improves the durability of the lock-up clutch 8.

In the lock-up state shown in FIG. 8, the entire facing material 86 is pressed against the annular region 43, and slippage stops. Since there is no problem with heat generation due to slippage of the facing material 86, there is no need to circulate oil OL through the oil passage OP3.

However, if the oil groove 490 is formed in the entire annular region 43 including the inner diameter region 44 as in Comparative Example 2 shown in FIG. 10, the oil passage OP3 is not closed even in the lock-up state, and oil OL flows between the facing material 86 and the annular region 43. The oil OL flowing between the facing material 86 and the annular region 43 applies hydraulic pressure in a direction that moves the piston 80 away from the front cover 4, which may affect the fastening of the facing material 86 and the front cover 4.

In the embodiment, as shown in FIG. 8, no oil groove 46 is formed in region 44, and the region 44 is a flat surface. Therefore, when the entire facing material 86 is pressed against the annular region 43, region 44 is in close contact with the facing material 86, closing oil passage OP3 and reducing the amount of oil OL passing between the facing material 86 and the annular region 43. This makes it possible to suppress any effect on the fastening of the facing material 86 and the front cover 4.

As described above, the torque converter 1 and the lock-up clutch 8 according to the embodiment have the following configurations.
(1) The torque converter 1 includes a front cover 4 that rotates around a rotation axis X (axis line),
A pump impeller 3 that rotates integrally with a front cover 4;
a turbine runner 5 provided on the rotation axis X and arranged opposite to the pump impeller 3;
and a lock-up clutch 8 that switches between fastening and releasing between the front cover 4 and the turbine runner 5.
The lock-up clutch 8 is
a piston 80 that is connected to the turbine runner 5 and is hydraulically driven in the direction of the rotation axis X to come into contact with and move away from the front cover 4;
When one of the mutually opposing surfaces 42, 85 of the front cover 4 and the piston 80 is defined as a first surface and the other as a second surface, an annular facing material 86 (friction material) provided on the first surface,
and an annular region 43 provided on the second surface and facing the annular facing material 86.
The annular region 43 is provided with a mesh-like oil groove 46 consisting of a plurality of continuous grooves.
In this embodiment, the surface 85 of the piston 80 is referred to as the "first surface," and the surface 42 of the front cover 4 is referred to as the "second surface."

When the lock-up clutch 8 is in a slipping state, the facing material 86 comes into contact with the annular region 43 of the front cover 4 while slipping, which may generate frictional heat.
In the embodiment, the oil groove 46 is provided in the annular region 43 of the front cover 4. The oil OL passes through the oil groove 46, thereby cooling the facing material 86 and the front cover 4, thereby making it possible to suppress heat generation.

Here, providing grooves 860 in the facing material 86 as in Comparative Example 1 may lead to peeling and wear of the facing material 86. In the embodiment, oil grooves 46 are provided in the front cover 4, which is a highly rigid metal member, so peeling and wear of the facing material 86 can be reduced. Furthermore, the oil grooves 46 can be arranged in a mesh-like pattern in the front cover 4, which is a metal member, so oil OL can be distributed evenly throughout the areas where the facing material 86 and the front cover 4 come into contact, effectively suppressing heat generation.

(2) The lock-up clutch 8 has an oil passage OP3 between the piston 80 and the front cover 4, through which the oil OL flows.
The piston 80 is connected to the turbine runner 5 at a cylindrical portion 81 (on the inner diameter side in the direction of the rotation axis X (axial line)) and is hydraulically driven at a disk portion 83 (on the outer diameter side in the direction of the rotation axis X) to come into contact with and move away from the front cover 4.
The annular region 43 has a region 45 (outer diameter side annular region) that contacts the facing material 86 (friction material) when the piston 80 is in a slipping state while contacting the front cover 4, and a region 44 (inner diameter side annular region) that is separated from the facing material 86.
The mesh-like oil grooves 46 are provided in the region 45 but not in the region 44 .

With this configuration, in a slip state, the oil OL passes between the front cover 4 and the facing material 86, allowing the oil OL to circulate in the oil passage OP3, thereby suppressing the rise in oil temperature.

On the other hand, if oil OL passes between the front cover 4 and the facing material 86 in the lockup state, hydraulic pressure will be applied in a direction that separates the front cover 4 and the piston 80, which may affect fastening.
According to the configuration of the embodiment, in the lockup state, the region 44 where the oil groove 46 is not formed is in close contact with the region 87, and the oil passage OP3 is closed. This makes it possible to suppress the oil OL from passing between the front cover 4 and the facing material 86 and affecting the fastening of the front cover 4 and the facing material 86.

(3) The mesh-like oil grooves 46 are made up of continuous polygonal grooves.
By configuring the oil groove 46 as a polygonal groove, grooves extending in different directions are spread throughout the entire region 45, so that the oil OL can be easily distributed throughout the entire region 45, and the cooling efficiency can be improved. In the embodiment, the hexagonal groove 460 is given as an example of a polygonal groove, but this is not limiting. Other polygonal shapes such as a triangle or a rectangle may also be used.

(4) The polygon is a hexagon.
By forming the oil groove 46 into a hexagonal groove 460, the oil groove 46 can be disposed in the region 45 without any gaps.

<Modification 1>
FIG. 11 is a diagram illustrating the configuration of an oil groove 46B according to the first modified example.
The hexagonal groove 460 described in the embodiment has the circumferential groove 461a (see FIG. 6) extending along the circumferential direction, but is not limited to this.
As shown in FIG. 11, a hexagonal groove 460B of the first modification is obtained by changing the orientation of the hexagonal groove 460 of the embodiment.
The hexagonal groove 460B extends along the radial direction of the rotation axis X and includes a pair of radial grooves 471a, 471a adjacent to each other in the radial direction of the rotation axis X. The pair of radial grooves 471a, 471a are connected by circumferential grooves 471b, 471c that extend in a zigzag manner with respect to a line segment parallel to the circumferential direction.

As in the embodiment, the hexagonal groove 460B in the first modified example also has grooves (radial grooves 471a, 471a and circumferential grooves 471b, 471c) extending in different directions that run throughout the entire region 45. This makes it easier for oil OL to spread throughout the entire region 45, and improves the cooling efficiency of the oil OL. In addition, by configuring the oil groove 46B from a hexagonal groove 460B, the oil groove 46 can be arranged without gaps in the region 45.

<Modification 2>
FIG. 12 is a diagram illustrating the configuration of an oil groove 46C according to the second modification.
12, the oil groove 46C may be formed of a continuous circular groove 460C. The circular groove 460C is a circular groove when viewed from the direction of the rotation axis X (see FIG. 2), and is formed to continue into the region 45 of the front cover 4, similar to the hexagonal groove 460.
As shown in FIG. 12, the circular groove 460C has a portion along the radial direction of the rotation axis X (see FIG. 2) and a portion along the circumferential direction, and shares a portion of the groove with another circular groove 460C adjacent to it in the radial and circumferential directions.

Since the circular groove 460C has portions along the radial and circumferential directions, the oil OL that has entered the oil groove 46C can easily spread throughout the entire region 45. In addition, since the circular groove 460C is formed at an equal distance from the center O, the oil OL can easily enter the circular groove 460C evenly.

As described above, the second modification has the following configuration.
(5) The mesh-like oil groove 46C is composed of continuous circular grooves 460C (circular grooves).
In the second modification, a circular groove 460C having radial and circumferential portions is arranged throughout the entire region 45. This makes it easier for the oil OL to reach the entire region 45, and improves the cooling efficiency by the oil OL.

<Modification 3>
1, in the embodiment, the surface of the piston 80 is the first surface on which the facing material 86 is provided, and the surface 42 of the front cover 4 is the second surface on which the annular region 43 is provided, but this is not limited to the above. The surface 42 of the front cover 4 may be the first surface on which the facing material is provided, and the surface 85 of the piston 80 may be the second surface on which the annular region is provided. Modification 3 is applicable not only to the embodiment, but also to Modifications 1 and 2.

The present invention is not limited to the embodiments and modifications described above, but may be modified as appropriate within the scope of the technical concept of the invention.

1 Torque converter 2 Converter housing 3 Pump impeller 4 Front cover 5 Turbine runner 6 Stator 8 Lock-up clutch 42 Surface (second surface)
43 Annular region 44 Region (inner diameter side annular region)
45 Area (Outer diameter annular area)
46 Oil groove 460 Hexagonal groove 80 Piston 85 Surface (first surface)
86 Facing material (friction material)
87 Area 88 Area OP3 Oil path X Rotating shaft (axis)

Claims (5)

A lock-up clutch that switches between engagement and release between a front cover of a torque converter that rotates about an axis and a turbine runner that is provided on the axis,
a piston connected to the turbine runner and driven in the axial direction by hydraulic pressure to come into contact with and move away from the front cover;
When one of the opposing surfaces of the front cover and the piston is defined as a first surface and the other is defined as a second surface, an annular friction material is provided on the first surface;
an annular region provided on the second surface and facing the annular friction material;
The annular region is provided with a mesh-like oil groove formed of a plurality of continuous grooves ,
an oil passage through which oil flows is provided between the piston and the front cover;
the piston is connected to the turbine runner at an inner diameter side in the axial direction, and is driven by the hydraulic pressure at an outer diameter side in the axial direction to come into contact with and move away from the front cover,
the annular region has an outer diameter side annular region that contacts the friction material in a slip state in which the piston contacts the front cover while slipping, and an inner diameter side annular region that is located on the inner diameter side of the outer diameter side annular region,
A lock-up clutch, wherein the mesh-like oil grooves are provided in the outer diameter side annular region and are not provided in the inner diameter side annular region . 2. The lock-up clutch according to claim 1 , wherein said mesh-like oil grooves are comprised of continuous polygonal grooves. 3. The lock-up clutch of claim 2 , wherein said polygon is a hexagon. 2. The lock-up clutch according to claim 1 , wherein said mesh-like oil groove is composed of continuous circular grooves. A front cover that rotates around an axis;
a pump impeller that rotates integrally with the front cover;
a turbine runner provided on the axis and arranged opposite to the pump impeller;
a lock-up clutch that switches between engagement and release between the front cover and the turbine runner,
The lock-up clutch is
a piston connected to the turbine runner and driven in the axial direction by hydraulic pressure to come into contact with and move away from the front cover;
When one of the opposing surfaces of the front cover and the piston is defined as a first surface and the other is defined as a second surface, an annular friction material is provided on the first surface;
an annular region provided on the second surface and facing the annular friction material;
The annular region is provided with a mesh-like oil groove formed of a plurality of continuous grooves ,
an oil passage through which oil flows is provided between the piston and the front cover;
the piston is connected to the turbine runner at an inner diameter side in the axial direction, and is driven by the hydraulic pressure at an outer diameter side in the axial direction to come into contact with and move away from the front cover,
the annular region has an outer diameter side annular region that contacts the friction material in a slip state in which the piston contacts the front cover while slipping, and an inner diameter side annular region that is located on the inner diameter side of the outer diameter side annular region,
A torque converter, wherein the mesh-like oil grooves are provided in the outer diameter side annular region and are not provided in the inner diameter side annular region .

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