JP4876474B2 - Friction fastening device for transmission - Google Patents

Description

  The present invention relates to a friction fastening device used as a multi-plate clutch or a multi-plate brake of a transmission.

  For example, in a transmission such as an automatic transmission mounted on an automobile, a multi-plate clutch is generally used as means for interrupting the driving force. For example, in an automatic transmission using a planetary gear, a multi-plate brake may be used as means for stopping rotation by integrating a fixed element with a transmission case or the like. Each of them includes a plurality of friction disks and plates arranged alternately so that their plate surfaces face each other, a cylinder part whose axial direction is the direction in which the friction disks and plates are arranged, and the inside of the cylinder part The hydraulic chamber is formed in the cylinder portion, and the pressure receiving surface formed between the outer peripheral seal portion and the inner peripheral seal portion receives the hydraulic pressure of the hydraulic chamber in the axial direction of the cylinder portion. A hydraulic piston that strokes and a pressing portion that presses the friction disk and the plate when the hydraulic piston strokes are provided. In this specification, the term “friction fastening device” refers to a multi-plate clutch or a multi-plate brake having such a structure, unless otherwise specified.

For example, Patent Document 1 proposes a friction fastening device (multi-plate clutch) for the purpose of realizing a reduction in size while ensuring a pressure receiving area of a hydraulic piston. As can be seen from Patent Document 1, the conventional friction fastening device strokes the hydraulic piston so as to move in parallel in the axial direction of the cylinder portion.
JP-A-11-182579

  However, the conventional structure has a problem in that it cannot sufficiently meet the control requirements of a friction fastening device that has been improved in accuracy in recent years.

  When a friction fastening device (hereinafter simply referred to as a clutch or the like) is engaged, the stroke of the hydraulic piston is from the start of introduction of hydraulic oil into the hydraulic chamber until the friction disk effectively transmits torque. There is a time lag (delay). Usually, since the pressure receiving surface of the hydraulic piston constitutes a part of the hydraulic chamber, the volume of the hydraulic chamber inevitably increases with the stroke of the hydraulic piston. Accordingly, during the stroke of the hydraulic piston, a volume of hydraulic oil corresponding to the volume of the hydraulic chamber that is increasing continues to flow. When the stroke of the hydraulic piston is completed, the substantial flow of the hydraulic oil into the hydraulic chamber is also completed. From the above, it can be said that the time lag is the time required for the hydraulic oil to completely flow into the increasing hydraulic chamber.

  Note that, during this piston stroke, the hydraulic pressure acting on the hydraulic piston hardly increases, so that the hydraulic characteristics are as if shelves were formed (see FIG. 4, time points t2 to t3 '). Therefore, the time lag is generally called hydraulic shelf time.

  From the viewpoint of controlling the operation of the clutch and the like, it is desirable that the hydraulic shelf time is short. If the hydraulic shelf time is long, it takes a long time until the clutch or the like is actually engaged from the engagement command to the clutch or the like issued from the control unit or the like. That is, the response of fastening is reduced. In addition, if the hydraulic shelf time is long, the engagement timing is likely to vary. For example, when performing engagement almost simultaneously with the release of other clutches, it becomes difficult to synchronize the operations at an appropriate timing, increasing the shift shock. There is a risk of causing it.

  In order to improve the feeling (shift quality) given to the occupant during gear shifting, it is desirable that the fastening response is high and the gear shift shock is small. For this purpose, it is desirable that the hydraulic shelf time is short.

  In recent years, when a clutch or the like is engaged, a slight hydraulic pressure is applied in advance, and the multi-plate clutch is operated from the latter half of the stroke to the vicinity of the final stage to make it a fine engagement state (in this specification, fine engagement control). Has been attracting attention and is being used frequently. When performing such fine engagement control, it is required to promptly shift from the fine engagement state to the fastening state. For this purpose, the stroke amount of the hydraulic piston is large with respect to the inflow amount of hydraulic oil into the hydraulic chamber, the stroke speed from the fine engagement state is high, in other words, the hydraulic shelf time from the fine engagement state is short. desirable.

  In order to shorten the hydraulic shelf time, for example, it seems to be sufficient to reduce the inflow amount of hydraulic oil by simply reducing the stroke amount of the hydraulic piston. This is because, as described above, the hydraulic shelf time is the time required for the hydraulic oil to completely flow into the hydraulic chamber. However, if the stroke amount of the hydraulic piston is simply shortened, the so-called drag phenomenon, in which some torque is transmitted, is not easily released in the released state of the clutch or the like. When this drag phenomenon occurs, fuel efficiency is deteriorated and wear of the friction disk is accelerated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a friction fastening device for a transmission that can reduce the hydraulic shelf time while suppressing the occurrence of a drag phenomenon.

The invention according to claim 1 of the present invention for solving the above-mentioned problems is a plurality of friction disks and plates arranged alternately so that their plate surfaces face each other, and the direction in which the friction disks and plates are arranged An axial direction of the cylinder part, a hydraulic chamber formed in the cylinder part,
A hydraulic piston that is provided in the cylinder part and receives a hydraulic pressure of the hydraulic chamber on a pressure receiving surface formed between the outer peripheral side seal part and the inner peripheral side seal part, and strokes in an axial direction of the cylinder part; In a friction fastening device for a transmission that includes a pressing portion that presses the friction disk and the plate when the piston strokes, the pressing portion and the inner peripheral side of the hydraulic piston move together in the same stroke. In addition , the outer circumferential side stroke amount of the pressure receiving surface of the hydraulic piston is configured to be shorter than the pressing portion and the inner circumferential side stroke amount.

  According to a second aspect of the present invention, in the friction fastening device for a transmission according to the first aspect, the pressure-receiving surface is constituted by a disc spring member, and the outer stroke amount of the disc spring member is set to be larger than the inner stroke amount. An outer circumferential side stroke amount regulating member that regulates within a short predetermined value is provided.

  According to a third aspect of the present invention, in the friction fastening device for a transmission according to the first aspect, the pressure-receiving surface is constituted by a disc spring member, and the outer periphery is engaged so as to restrict the outer stroke of the disc spring member. A side locking member is provided.

  According to a fourth aspect of the present invention, in the frictional engagement device for a transmission according to the second or third aspect, an inner diameter of the friction disk and the plate is larger than an inner diameter of the hydraulic piston, and an inner peripheral side of the hydraulic piston and the above A pressing force transmission member that integrally connects the pressing portion is provided.

  According to a fifth aspect of the present invention, in the frictional fastening device for a transmission according to any one of the second to fourth aspects, the disc spring member includes a plurality of disc springs having different inner and outer diameters arranged concentrically. It is characterized by comprising.

  According to a sixth aspect of the present invention, in the friction fastening device for a transmission according to any one of the first to fifth aspects, between the outer peripheral side seal portion and the inner peripheral side seal portion of the pressure receiving surface, A partition seal portion that partitions the hydraulic chamber into a plurality of hydraulic chambers is provided.

  According to a seventh aspect of the present invention, in the friction fastening device for a transmission according to any one of the first to sixth aspects, even if the friction material of the friction disk is worn, the inner peripheral stroke amount and the outer peripheral An automatic stroke amount adjusting device that automatically adjusts so that the difference from the side stroke amount does not exceed a predetermined value is provided.

  According to the first aspect of the present invention, for example, the stroke amount on the inner peripheral side of the pressure receiving surface of the hydraulic piston can be set to the same level as the conventional structure, and only the stroke amount on the outer peripheral side can be shortened. In this way, the amount of hydraulic oil flowing into the hydraulic chamber can be greatly reduced compared to the conventional structure in which the entire hydraulic piston moves in parallel and the stroke amount of the inner and outer circumferences is equal. That is, the hydraulic shelf time can be effectively shortened.

  Therefore, it is easy to realize a shift with high shift quality by improving the engagement response of a clutch or the like or suppressing a shift shock. Further, when fine engagement control is performed, it is advantageous that the stroke speed of the hydraulic piston from the fine engagement state (after the second half of the piston stroke) can be increased.

  Further, at least near the end of the stroke of the hydraulic piston, only the inner peripheral side is in a stroke state. Therefore, no sliding resistance occurs at the outer peripheral side seal portion. That is, at least near the end of the stroke of the hydraulic piston, the sliding resistance of the hydraulic piston can be reduced as compared with the conventional structure in which the hydraulic piston moves in parallel. If the sliding resistance of the hydraulic piston is large, it is necessary to increase the supply hydraulic pressure accordingly, which tends to increase the shift shock, but reducing the sliding resistance can contribute to further improving the shift shock. it can.

  According to the invention of claim 2, when the stroke of the hydraulic piston is stroked, the outer stroke side regulating amount of the pressure receiving surface is regulated by the outer circumference side stroke regulating member, and then the disc spring member is bent to further stroke only the inner circumference side. Can do. That is, the stroke difference between the inner and outer circumferences of the pressure receiving surface can be absorbed by the deflection of the disc spring member. Thus, the inner and outer peripheral stroke difference of the pressure receiving surface of the hydraulic piston can be easily created with a simple structure in which the pressure receiving surface is formed of a disc spring member and the outer peripheral stroke amount regulating member is provided.

  According to the invention of claim 3, when the hydraulic piston is stroked, the inner peripheral side stroke of the pressure receiving surface is regulated by the outer peripheral side locking member, and the disc spring member is bent to stroke only the inner peripheral side. it can. That is, the stroke amount on the inner peripheral side of the pressure receiving surface can be created by the deflection of the disc spring member. As described above, the inner pressure side stroke amount of the pressure receiving surface of the hydraulic piston can be easily created with a simple structure in which the pressure receiving surface is constituted by the disc spring member and the outer peripheral side locking member is provided.

  According to the invention of claim 4, even when the inner diameter of the friction disk and the plate is larger than the inner diameter of the hydraulic piston and it is difficult to provide the pressing portion in the vicinity of the inner peripheral side of the hydraulic piston, the pressing force transmitting member is interposed. By providing the pressing portion, it is possible to reliably transmit the pressing force from the inner peripheral side of the hydraulic piston to the pressing portion.

  According to the invention of claim 5, the difference between the inner and outer peripheral strokes per disc spring member can be reduced. Therefore, the internal stress due to the deflection of the disc spring member when the hydraulic piston is stroked can be reduced.

  According to the sixth aspect of the present invention, as will be described below, it is possible to achieve a higher shift quality by optimizing the gain of the transmission torque of the clutch or the like.

  The gain of the transmission torque is the increment of the transmission torque with respect to the increase of the hydraulic pressure. If other conditions are the same, the gain increases as the pressure receiving area of the hydraulic piston increases.

  If the gain is too large, the transmission torque will fluctuate more than necessary due to slight fluctuations or variations in the working oil pressure, causing adverse effects such as an increase in shift shock. On the other hand, if the gain is too small, the necessary transmission torque cannot be obtained sufficiently, or the fastening timing delay increases. Since any of these causes deterioration of the shift quality, it is desirable that the gain of the transmission torque is within an appropriate range. Generally, the appropriate gain increases as the required transmission torque increases.

  Further, when performing the fine engagement control, it is desirable to reduce the gain in order to reduce the variation in the hydraulic piston position with respect to the variation in hydraulic pressure in the fine engagement state.

  Therefore, according to the configuration of the present invention, since the hydraulic chamber is partitioned by the partition seal portion, the hydraulic oil can be introduced into only a part of the partitions. The actual pressure receiving area of the hydraulic piston is the total area of the pressure receiving surface corresponding to the hydraulic chamber in the section where the hydraulic oil is introduced. Therefore, the actual pressure receiving area of the hydraulic piston can be changed simply by changing the section where the hydraulic oil is introduced. Can be changed to increase or decrease the gain.

  Therefore, higher shift quality can be realized by engaging the clutch or the like with an appropriate gain according to the required transmission torque. Further, when performing the fine engagement control, it is effective because the gain can be easily reduced.

  According to the seventh aspect of the present invention, it is possible to eliminate the influence of the difference between the inner peripheral stroke amount and the outer peripheral stroke amount being excessively increased due to wear of the friction material. That is, the influence due to the change with time can be suppressed as much as possible.

  The friction material of the friction disk gradually wears with use (change over time). Therefore, when the hydraulic piston strokes from the release position to the fastening position, the stroke amount of the pressing portion increases. In the configuration of the present invention, since the pressing portion is provided so as to move integrally with the inner circumferential side of the hydraulic piston, the stroke amount on the inner circumferential side of the pressure receiving surface of the hydraulic piston eventually increases.

  Here, if the outer peripheral stroke amount is unchanged (including those that do not start from the beginning), the difference between the inner peripheral stroke amount and the outer peripheral stroke amount is increased. When the stroke difference between the inner and outer circumferences increases, for example, when a disc spring member is used, the internal stress of the disc spring member increases, and thus it is easily affected unfavorably.

  Therefore, according to the configuration of the present invention, the automatic stroke amount adjusting device automatically adjusts so that the inner and outer stroke differences do not exceed a predetermined value, thereby eliminating the influence of the inner and outer stroke differences being excessively large. It can be done.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a multi-plate clutch 10 which is a first embodiment of a friction fastening device according to the present invention and its peripheral portion. FIG. 2 is an enlarged cross-sectional view showing an essential part of FIG. However, in FIG. 2, the operation in the axial direction of the clutch piston 20 is exaggerated for easy understanding of the drawing.

  As shown in FIG. 1, a multi-plate clutch 10 is a wet hydraulic clutch for an automatic transmission, and includes a turbine shaft 3 as an input shaft and a sun gear (in detail, from a sun gear provided at the center of a planetary gear not shown). This is an apparatus for interrupting the driving force with the extended sun gear extension 50). The multi-plate clutch 10 of this embodiment is provided in the vicinity of an oil pump housing 70 fixed to a transmission case (not shown) and an oil pump cover 71 fixed to the oil pump housing 70 with bolts 72.

  The clutch drum 11 (rotary drum) of the multi-plate clutch 10 is formed in a substantially bottomed cylindrical shape, and the center of the bottom surface is recessed so as to be fitted to the boss portion 75 of the oil pump cover 71. The clutch drum 11 is joined to the turbine shaft 3 at the recess. Therefore, the clutch drum 11 rotates integrally with the turbine shaft 3.

  On the other hand, the clutch hub drum 40 is a member formed in a stepped cylindrical shape having a small diameter portion and a large diameter portion, and a spline portion 42 is formed in the small diameter portion. Further, the turbine shaft 3 and the sun gear extension 50 are passed through the small diameter portion, and the spline part 52 formed in the sun gear extension 50 and the spline part 42 are engaged with each other. Therefore, the clutch hub drum 40 basically rotates integrally with the sun gear extension 50, although it has a slight degree of freedom in axial movement.

  As a member that directly connects and disconnects the clutch drum 11 that rotates integrally with the turbine shaft 3 and the clutch hub drum 40 that rotates integrally with the sun gear extension 50, four plates 35 and a clutch hub drum 40 are provided on the clutch drum 11 side. Four clutch disks 30 are provided on the side.

  The plate 35 is a metal annular plate, and its outer peripheral side is engaged with a plate hub portion 19 formed on the clutch drum 11. A spline extending in the axial direction is formed on the plate hub portion 19, and irregularities that fit into the spline are formed on the outer peripheral side of the plate 35. Therefore, the plate 35 rotates integrally with the clutch drum 11 while having a degree of freedom to move in the axial direction.

  The clutch disk 30 is a friction disk in which a friction material 31 (see FIG. 2) is attached to both front and back surfaces of a metal annular plate, and its inner peripheral side is engaged with the clutch disk hub portion 41 of the clutch hub drum 40. . A spline extending in the axial direction is formed in the clutch disc hub portion 41, and irregularities that fit into the spline are formed on the inner peripheral side of the clutch disc 30. The clutch disk 30 rotates integrally with the clutch hub drum 40 while having a degree of freedom to move in the axial direction.

  As shown in FIG. 1, the clutch disks 30 and the plates 35 are alternately arranged in such a manner that their plate surfaces face each other. The end of the row ends with the plate 35 on the bottom side (right end in the figure) of the clutch drum 11 and ends with the clutch disk 30 on the opening side (left end in the figure). The leftmost clutch disk 30 in the drawing is restricted from moving to the left in the drawing by a snap ring 38 via a retaining plate 37.

  On the bottom surface side of the clutch drum 11, a cylinder portion 11 a is formed in which the direction in which the clutch disk 30 and the plate 35 are arranged is an axial direction. As shown in FIG. 2, a hydraulic chamber 12 is formed in a substantially annular space in the cylinder portion 11 a, and a clutch piston 20 is fitted so as to close the hydraulic chamber 12.

  The main part of the clutch piston 20 is a disc spring member 22 of an annular disk. The disc spring member 22 is configured by arranging three disc springs having different inner and outer diameters on a concentric circle. That is, the 1st disc spring member 22a, the 2nd disc spring member 22b, and the 3rd disc spring member 22c are arrange | positioned in order from the inner peripheral side. The outer peripheral side of the first Belleville spring member 22a and the inner peripheral side of the second Belleville spring member 22b are partially overlapped, and are joined by the joining member 23 at the overlapping portion without a gap. Similarly, the outer peripheral side of the second Belleville spring member 22b and the inner peripheral side of the third Belleville spring member 22c partially overlap, and the overlapping portion is joined without a gap by the joining member 24. The joining members 23 and 24 are made of an elastic member (for example, a rubber member) having a sealing property.

  A substantially cylindrical piston boss portion 29 having an inner diameter substantially equal to the inner diameter of the first disc spring member 22a is joined to the inner peripheral side of the surface of the first disc spring member 22a facing the plate 35. The base end side (right side in the illustrated state) of the piston boss portion 29 is joined to the first disc spring member 22a via the joining member 34 without a gap. The material of the joining member 34 is the same as that of the joining members 23 and 24.

  On the other hand, the tip end side (left side in the illustrated state) of the piston boss portion 29 extends toward the plate 35. A pressing force transmission member 32 is fitted on the outer peripheral side. The pressing force transmission member 32 is fixed to the piston boss portion 29 by a snap ring 33.

  The pressing force transmission member 32 is a dish-shaped member formed by bending the outer peripheral side of a disk-shaped member provided coaxially with the cylinder portion 11a toward the plate 35 to form an edge portion 32a. The diameter of the edge portion 32a is set to a value near the middle between the inner diameter and the outer diameter of the plate 35. And the press part 32b which presses the plate 35 directly is formed in the front-end | tip part of the edge part 32a.

  The pressing portion 32 b moves integrally with the inner peripheral side of the clutch piston 20 together with the piston boss portion 29 and the pressing force transmission member 32. That is, when the clutch piston 20 makes a stroke, the pressing portion 32b moves in the axial direction by a length equal to the inner circumferential stroke amount L3 and presses the plate 35.

  A rubber-based inner peripheral side seal portion 26 is provided on the inner peripheral side of the piston boss portion 29, and the piston boss portion 29 is maintained while maintaining a seal between the inner peripheral side of the piston boss portion 29 and the hydraulic chamber inner peripheral surface 12a. It is possible to move in the axial direction. Further, a rubber-based outer peripheral side seal portion 27 is provided on the outer peripheral side of the third disc spring member 22c, and the third outer periphery of the third disc spring member 22c and the hydraulic chamber outer peripheral surface 12b are maintained while being sealed. The disc spring member 22c can be moved in the axial direction. Thus, there is a portion that contacts the hydraulic chamber 12 from the innermost peripheral portion where the inner peripheral seal portion 26 and the hydraulic chamber outer peripheral surface 12a abut to the outermost peripheral portion where the outer peripheral seal portion 27 and the hydraulic chamber outer peripheral surface 12b abut. It is a pressure receiving surface 21 of the clutch piston 20.

  A return spring 45 is provided on the outer peripheral side of the third disc spring member 22 c and on the back side of the pressure receiving surface 21. The return spring 45 is a coil spring, one end of which is supported by the clutch drum 11 by a snap ring 47 via a spring retainer 46, and the other end is in contact with the third disc spring member 22c. Accordingly, the return spring 45 constantly urges the clutch piston 20 in the direction away from the plate 35 (clutch release side).

  An outer peripheral stroke amount restricting portion 46a is formed at a position of the spring retainer 46 facing the third disc spring member 22c. When the clutch piston 20 is in a pre-stroke state (indicated by a two-dot chain line in FIG. 2), a predetermined gap L1 (as will be described later) is provided between the outer peripheral stroke amount regulating portion 46a and the third disc spring member 22c. Furthermore, this is the outer peripheral stroke amount L1). When the clutch piston 20 is stroked by L1, the third disc spring member 22c comes into contact with the outer circumferential side stroke amount restricting portion 46a, and further stroke is prevented. That is, the outer peripheral stroke amount of the clutch piston 20 is restricted to L1. The outer peripheral stroke amount L1 is set to be smaller than the inner peripheral stroke amount L3.

  The hydraulic chamber 12 is a space formed in the cylinder portion 11a. Specifically, the hydraulic chamber 12 is surrounded by the bottom surface of the clutch drum 11, the hydraulic chamber inner peripheral surface 12a, the hydraulic chamber outer peripheral surface 12b, and the pressure receiving surface 21 of the clutch piston 20. Space. The cylinder portion 11 a is provided with an oil introduction hole 13 that opens to the outside from the peripheral surface 12 a of the hydraulic chamber, and hydraulic oil is supplied to and discharged from the hydraulic chamber 12 through the oil introduction hole 13. As shown in FIG. 1, a boss portion 75 of the oil pump cover 71 is provided with a clutch hydraulic pressure supply portion 77 that communicates with the oil introduction hole 13. The hydraulic oil controlled by a control valve or the like (not shown) is configured to be guided to the clutch hydraulic pressure supply unit 77 via the inside of the oil pump cover 71 or the like.

As shown in FIG. 2, a bent disc-shaped balance piston 15 is provided on the back side of the surface of the pressing force transmission member 32 that faces the clutch piston 20. The inner peripheral side of the balance piston 15 is fixed to the turbine shaft 3 by a snap ring 16 (see FIG. 1). A balance piston seal portion 17 is provided on the outer peripheral side of the balance piston 15, and the outer peripheral side of the balance piston seal portion 17 is in contact with the inner peripheral side of the edge portion 32 a of the pressing force transmitting member 32 while maintaining a seal. A hydraulic balance chamber 18 is formed in a space sandwiched between the pressing force transmission member 32 and the balance piston 15. The hydraulic balance chamber 18 is configured so that a part of the lubricating oil is supplied from a lubricating oil passage 4a described later.

  As shown in FIG. 1, each part that needs lubrication, for example, a bush 51 provided between the turbine shaft 3 and the sun gear extension 50, and between the turbine shaft 3 and the boss inner peripheral part of the oil pump cover 71. In order to guide the lubricating oil to the bush 76 and the clutch drum 11 provided, and the thrust washer 79 provided between the boss front end surface of the oil pump cover 71 and the like, lubricating oil passages are provided in various places. For example, the lubricating oil passage 4 is provided in the axial center part of the turbine shaft 3, and it branches from this and the lubricating oil passages 4a and 4b are provided. As described above, part of the lubricating oil guided to the lubricating oil passage 4 a is guided to the hydraulic balance chamber 18.

  Next, the operation of the multi-plate clutch 10 will be described. First, the case where the multi-plate clutch 10 is off, that is, in the released state will be described. Regarding the operation direction of the clutch piston 20 in the following description, the rightward movement in FIGS. 1 and 2 is the release side, and the leftward movement is the fastening side.

  When the multi-plate clutch 10 is off, hydraulic oil is not introduced into the hydraulic chamber 12. The clutch piston 20 is brought closer to the release side by the urging force of the return spring 45 (shown by a two-dot chain line in FIG. 2). Therefore, the plate 35 and the pressing portion 32b are separated from each other, and the plate 35 does not receive the pressing force from the clutch piston 20. At this time, there is an appropriate gap (clearance) between each clutch disk 30 and each plate 35, and there is almost no torque transmission. Therefore, the torque transmission between the clutch drum 11 and the clutch hub drum 40, and consequently the turbine shaft 3 and the sun gear extension 50 is cut off. The turbine shaft 3 and the sun gear extension 50 are rotatable relative to each other as necessary.

  Next, the case where the multi-plate clutch 10 is on, that is, in the engaged state will be described. When the multi-plate clutch 10 is on, hydraulic oil is introduced into the hydraulic chamber 12 through the oil introduction hole 13. When the hydraulic oil fills the hydraulic chamber 12, the hydraulic pressure (hereinafter referred to as clutch hydraulic pressure Pc) is received by the pressure receiving surface 21 of the clutch piston 20. That is, the clutch piston 20 is pressed to the engagement side. When the pressing force by the clutch hydraulic pressure Pc becomes larger than the sum of the urging force by the return spring 45 and the sliding resistance of the inner peripheral side seal portion 26 and the outer peripheral side seal portion 27, the clutch piston 20 starts to stroke toward the fastening side.

  In the present embodiment, the clutch piston 20 moves in parallel as a whole in the initial stroke. That is, the stroke amount on the inner peripheral side is equal to the stroke amount on the outer peripheral side. When the stroke is made by the outer peripheral stroke amount L1, the third disc spring member 22c comes into contact with the outer peripheral stroke amount regulating portion 46a of the spring retainer 46, and further strokes are prevented.

  When the clutch hydraulic pressure Pc further increases, the clutch piston 20 further strokes only on the inner peripheral side. That is, the inner circumference side of each of the first disc spring member 22a, the second disc spring member 22b, and the third disc spring member 22c constituting the clutch piston 20 bends toward the fastening side, so that the entire clutch piston 20 is also fastened on the inner circumference side. Bend to the side.

  On the other hand, when the stroke of the clutch piston 20 proceeds to some extent, the pressing portion 32b comes into contact with the plate 35 and starts pressing. As the stroke of the clutch piston 20 progresses, the clearance between the plate 35 and the friction material 31 is reduced. When there is almost no clearance, a frictional force begins to act between the friction material 31 of the clutch disk 30 and the clutch disk 30 in a direction that prevents relative rotation of each other. Torque is transmitted between the clutch drum 11 and the clutch hub drum 40, and consequently the turbine shaft 3 and the sun gear extension 50, by this frictional force. Until the clearance between the plate 35 and the friction material 31 is completely closed (the stroke of the clutch piston 20 is completed), the transmission torque capacity is small (fine engagement state).

  The inner stroke L3 when the stroke of the clutch piston 20 is completed is the outer stroke L1 and the disc spring deflection L2 (first disc spring member 22a, second disc spring member 22b and third disc spring member 22c). The total amount of bending of the disc spring member 22 including the total amount of each of the bending). That is, the inner peripheral stroke amount L3 = the outer peripheral stroke amount L1 + the Belleville spring deflection amount L2.

  When the stroke of the clutch piston 20 is completed and the clearance between the plate 35 and the friction material 31 is completely closed, the frictional force acting between the plate 35 and the friction material 31 is further increased, and the transmission torque capacity is increased. When there is relative rotation between the plate 35 and the friction material 31, the multi-plate clutch 10 is in a semi-engaged state, and torque transmission is not yet complete.

  Further, when the clutch hydraulic pressure Pc becomes sufficiently high and a sufficiently large pressing force is applied to the plate 35 from the pressing portion 32b, a sufficiently large frictional force is applied between the plate 35 and the friction material 31 to complete integration. At this time, the turbine shaft 3 and the sun gear extension 50 rotate together, and complete torque transmission is performed. That is, the engagement of the multi-plate clutch 10 is completed.

  Next, the operation of the balance piston 15 and the hydraulic balance chamber 18 will be described. Since the clutch drum 11 rotates integrally with the turbine shaft 3, centrifugal hydraulic pressure corresponding to the rotational speed of the turbine shaft 3 acts on the hydraulic oil in the hydraulic chamber 12. Centrifugal oil pressure is an additional oil pressure generated by centrifugal force. By this centrifugal oil pressure, the average oil pressure acting on the pressure receiving surface 21 becomes higher than the control pressure in the clutch oil pressure supply unit 77. Centrifugal oil pressure increases as the rotational speed of the clutch drum 11 increases, and cannot be ignored for highly accurate control. Therefore, there is known a technique for preventing the centrifugal hydraulic pressure from being generated or preventing the centrifugal hydraulic pressure from being substantially affected even if it occurs. The balance piston 15 and the hydraulic balance chamber 18 are known techniques belonging to the latter.

  When a part of lubricating oil (hereinafter referred to as balance oil) is introduced into the hydraulic balance chamber 18, centrifugal oil pressure also acts on the balance oil. The centrifugal hydraulic pressure acts on the pressing force transmission member 32 and presses it toward the clutch release side. The pressing force acts on the back side of the pressure receiving surface 21 via the piston boss portion 29. This pressing force is almost offset with the pressing force to the fastening side by the centrifugal oil pressure acting on the hydraulic oil in the hydraulic chamber 12. That is, the clutch piston 20 performs substantially the same operation as when no centrifugal oil pressure is applied. As a result, the influence of complicated centrifugal oil pressure can be eliminated and highly accurate control can be performed.

  Next, the stroke amount of the clutch piston 20 and the amount of hydraulic oil introduced into the hydraulic chamber 12 will be described.

  FIG. 3 is an explanatory diagram showing the concept of volume increment ΔV of the hydraulic oil introduced into the hydraulic chamber 12. Here, the cylinder portion 11a is a complete cylinder, and the clutch piston 20 is also simplified to be a flat disk. FIG. 3 shows a case where the clutch piston 20 strokes from the upper right to the lower left. The volume increment ΔV is an increment of the hydraulic oil volume from when the hydraulic pressure is filled in the hydraulic chamber 12 before the clutch piston 20 starts the stroke until the stroke is completed.

  The stroke amount on the outer peripheral side until the third disc spring member 22c abuts on the outer stroke side regulating portion 46a is L1. The stroke amount on the inner peripheral side is L3 longer than that by the disc spring deflection amount L2.

  Here, if the volume V1 is a volume increment when the clutch piston 20 is stroked by the outer peripheral stroke amount L1, the volume V1 is a cylindrical volume having a height L1. When the volume V2 is a volume increment when the inner peripheral side of the clutch piston 20 further strokes to the inner peripheral stroke amount L3, the volume V2 is the volume of the hollow truncated cone having the height L2. The volume increment ΔV is the sum of the volume V1 and the volume V2. That is, ΔV = V1 + V2.

  Here, assuming that the volume of the cylinder having the height L2 is V2 + V3, V1 + V2 + V3 (= ΔV + V3) corresponds to a case where the stroke is the inner circumferential side stroke amount L3 on both the inner circumferential side and the outer circumferential side, that is, an increase in volume in the conventional structure. That is, in this embodiment, the volume increment ΔV is reduced by the volume V3 with respect to the conventional structure by making the outer stroke side L1 shorter than the inner stroke L3 by the disc spring deflection L2. . The volume V3 is 1/2 to 2/3 of the volume (V2 + V3) (depending on the ratio of the inner and outer diameters).

  Next, the effect of reducing the volume increment ΔV on the clutch hydraulic pressure characteristics will be described. FIG. 4 is a graph showing clutch hydraulic pressure characteristics at the time of shifting. The horizontal axis represents time t, and the vertical axis represents the clutch hydraulic pressure Pc.

  The change in the clutch oil pressure Pc will be described in time series. First, at time 0, hydraulic oil starts to be supplied from the control valve (not shown) to the hydraulic chamber 12 via the clutch oil pressure supply unit 77 and the oil introduction hole 13. At time t1, the hydraulic chamber 12 is filled with hydraulic oil, and the clutch hydraulic pressure Pc starts to increase. At time t2, the clutch hydraulic pressure Pc becomes a hydraulic pressure that corresponds to the force that overcomes the biasing force of the return spring 45 and the sliding resistance of the inner peripheral side seal portion 26 and the outer peripheral side seal portion 27, and the stroke of the clutch piston 20 starts.

  After the time point t2 when the stroke of the clutch piston 20 starts, the increase in the clutch hydraulic pressure Pc becomes temporarily slow. This is a kind of accumulator action due to the volume of the hydraulic chamber 12 being increased by the stroke of the clutch piston 20. At time t3, the stroke of the clutch piston 20 is completed (clutch oil pressure Pc = P1). The hydraulic shelf time tm is from time t2 when the clutch piston 20 is stroked to time t3.

  After time t3, the clutch hydraulic pressure Pc rapidly increases again. Then, at the time t4 when the clutch hydraulic pressure Pc becomes a predetermined pressure, the accumulator (not shown) starts to operate. Since the accumulator is a known mechanism, a detailed description thereof is omitted, but as the clutch hydraulic pressure Pc increases, the volume of the oil passage reaching the clutch hydraulic pressure supply unit 77 is increased to slow the increase of the clutch hydraulic pressure Pc. Due to the effect of the accumulator, rapid engagement between the plate 35 and the clutch disk 30 is prevented, and the shift shock is mitigated. At time t5, the engagement is completed and the shift is completed. Thereafter, the operation of the accumulator is completed at time t6, and the clutch hydraulic pressure Pc rises to a sufficiently high line pressure at time t7.

  Here, the fine engagement control will be described. In the fine engagement control, the clutch hydraulic pressure Pc is set to the hydraulic pressure P1 or slightly lower than the hydraulic pressure P1 in advance before the start of shifting, and the clutch piston 20 is operated from the latter half of the stroke to the vicinity of the final stage so as to be in the finely engaged state. Control. According to the fine engagement control, the process from the time point 0 to the time point t3 can be almost completed before the start of the shift, so that the process after the vicinity of the time point t3 can be started immediately after the shift start time. That is, since the time from time 0 to about time t3 is shortened, it is effective control particularly when quick fastening is required.

  For comparison, FIG. 4 shows a clutch hydraulic pressure characteristic of a conventional structure (in which both the inner peripheral side and the outer peripheral side are stroked by the stroke amount L3) by a two-dotted line. In addition, time points corresponding to the time points t3 and t5 in this case are indicated by time points t3 'and t5', respectively. As described above, in the present embodiment, since the volume increment ΔV is reduced by the volume V3 with respect to the conventional structure, the hydraulic shelf time tm is shortened by the time Δt (= t3′−t3) accordingly. Accordingly, the time t5 when the engagement of the multi-plate clutch 10 is completed is also shortened by the time Δt. That is, the remarkable effect that the engagement responsiveness of the multi-plate clutch 10 is improved by reducing the volume increment ΔV is achieved.

  In addition, since the stroke amount of the pressing portion 32b that moves integrally with the inner peripheral side of the clutch piston 20 is secured to a sufficient length of the inner peripheral side stroke amount L3, the clutch drag phenomenon occurs when the clutch piston 20 is released. There are no worries. Furthermore, since the time required for energy absorption from when the clearance between the plate 35 and the clutch disk 30 disappears until the engagement is completed is not shortened (t5−t3 = t5′−t3 ′), the shift shock becomes worse. In addition, the fastening response can be enhanced while maintaining a high shift quality.

  Further, when the hydraulic shelf time tm is shortened, the variation thereof is also reduced, and as a result, the variation in the fastening timing can also be reduced. Therefore, for example, when the engagement is performed substantially simultaneously with the release of other clutches, the operations can be synchronized with each other at a more appropriate timing, and variation in shift shock can be reduced. That is, the shift quality can be increased.

  In addition, when performing fine engagement control, the stroke of the clutch piston 20 can be changed to a stroke completion state more quickly from a state where the stroke of the clutch piston 20 is in the second half or near the end, so that responsiveness can be improved and variation in engagement timing can be reduced. it can.

  Further, in the latter half of the stroke of the clutch piston 20, only the inner peripheral side is in a stroke state. Therefore, no sliding resistance occurs at the outer peripheral side seal portion 27. That is, in the second half of the stroke of the clutch piston 20, the sliding resistance of the clutch piston 20 can be reduced as compared with the conventional structure in which the clutch piston moves in parallel. If the sliding resistance of the clutch piston 20 is large, it is necessary to increase the hydraulic pressure of the hydraulic chamber 12 correspondingly, and this tends to increase the shift shock. However, reducing the sliding resistance further improves the shift shock. Can contribute.

  Further, in this embodiment, the volume increment ΔV is reduced by making the outer peripheral stroke amount L1 shorter than the inner peripheral stroke amount L3 by the outer peripheral stroke amount regulating portion 46a. Absorbed in an amount L2. That is, the pressure receiving surface 21 of the clutch piston 20 is constituted by the disc spring member 22, and the volume increment ΔV is greatly reduced with a simple structure in which the outer peripheral stroke amount restricting portion 46a is provided.

  In addition, the disc spring member 22 is configured by concentrically arranging three disc springs having different inner and outer diameters, ie, a first disc spring member 22a, a second disc spring member 22b, and a third disc spring member 22c. The difference between the inner and outer peripheral strokes per disc spring member can be reduced. Therefore, it is possible to reduce internal stress due to the bending of each disc spring member when the clutch piston 20 is stroked.

  In this embodiment, the inner diameter of the plate 35 is larger than the inner diameter of the clutch piston 20, and it is difficult to provide a pressing portion near the inner peripheral side of the clutch piston 20. However, by providing the pressing force transmission member 32, the pressing force can be reliably transmitted from the inner peripheral side of the clutch piston 20 to the pressing portion 32b.

  Next, a second embodiment according to the present invention will be described. FIG. 5 is a cross-sectional view of the multi-plate clutch 10 in the second embodiment. In the drawings referred to in the following embodiments, components having the same or similar functions as those in the first embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

  The main difference between the present embodiment and the first embodiment is that the pressure receiving surface 61 of the clutch piston 60 is constituted by a single disc spring member 62 and that no return spring is provided. The axial movement of the outer peripheral side of the clutch piston 60 is restricted by a snap ring 65 that engages with the inner peripheral surface of the clutch drum 11. That is, the snap ring 65 acts as an outer peripheral side locking member, and the outer peripheral side stroke amount of the clutch piston 60 is substantially zero.

  Since the clutch piston 60 does not stroke on the outer peripheral side, the inner peripheral stroke amount L4, that is, the amount of deflection of the disc spring member 62 is obtained. In this case, the volume increment ΔV does not have a portion corresponding to the volume V1 in FIG. 3, and is all a portion corresponding to the volume V2. Here, if the inner peripheral stroke amount L3 = the inner peripheral stroke amount L4, the reduction rate of the volume increment ΔV is larger than that in the first embodiment.

  In the second embodiment, as in the first embodiment, the engagement response can be improved while maintaining a high shift quality without causing the clutch drag phenomenon and the deterioration of the shift shock. Further, variation in shift shock can be reduced. Even during fine engagement control, it is possible to improve responsiveness and reduce variations in fastening timing.

  Further, since the outer peripheral side of the clutch piston 60 is not stroked, sliding resistance in the outer peripheral side seal portion 27 does not occur. That is, the sliding resistance of the clutch piston 60 can be reduced as compared with the conventional structure in which the clutch piston moves in parallel. This can further contribute to the improvement of the shift shock.

  In the present embodiment, the volume increment ΔV is reduced by stroking only the inner peripheral side without stroking the outer peripheral side of the clutch piston 60, but the inner peripheral side stroke is caused to bend the disc spring member 62. It absorbs with. That is, the volume increment ΔV is greatly reduced with a simpler structure than that of the first embodiment in which the pressure receiving surface 61 of the clutch piston 60 is configured by a single disc spring member 62.

  Next, a third embodiment according to the present invention will be described. FIG. 6 is a cross-sectional view of the multi-plate clutch 90 in the third embodiment.

  The main difference between the present embodiment and the first embodiment is that the cylinder portion 91a of the clutch drum 91 has two compartments, that is, an inner peripheral first hydraulic chamber 92 and an outer peripheral second hydraulic chamber 93. Is provided (two-stage type).

  The clutch drum 91 includes a first drum 94a on the outer peripheral side and a second drum 94b on the inner peripheral side. A bulging portion 94c bulging toward the second hydraulic chamber 93 is formed on the outer peripheral side of the second drum 94b.

  The second drum 94b is provided with a first oil introduction hole 13a that communicates with the first hydraulic chamber 92 and a second oil introduction hole 13b that communicates with the second hydraulic chamber 93. Hydraulic oil is supplied independently.

  Moreover, the partition seal | sticker part 25 is provided in the pressure-receiving surface 96 side of the outer peripheral side of the 1st disc spring member 22a. The partition seal portion 25 is in contact with the inner peripheral portion of the bulging portion 94c, and partitions the first hydraulic chamber 92 and the second hydraulic chamber 93 at the contact portion. Accordingly, the inner peripheral portion of the bulging portion 94c is the first hydraulic chamber outer peripheral surface 92b and the second hydraulic chamber inner peripheral surface 93a.

  The partition seal portion 25 extends to the inner peripheral side of the first disc spring member 22a, contacts the first hydraulic chamber inner peripheral surface 92a, and has a sealing action corresponding to the inner peripheral seal portion 26 in the first embodiment. Do. Accordingly, the inner peripheral side seal portion 26 is not provided on the inner peripheral portion of the piston boss portion 29.

  Similarly to the second embodiment, no return spring is provided, and the stroke of the outer peripheral side of the third disc spring member 22c is restricted by the snap ring 65.

  With the above configuration, when the hydraulic pressure is applied to the first hydraulic chamber 92, the inner peripheral side of the pressure receiving surface 96 of the clutch piston 95 is pressed, and when the hydraulic pressure is applied to the second hydraulic chamber 93, the outer peripheral side of the pressure receiving surface 96 is pressed. Is done. When the hydraulic pressure is applied to both the first hydraulic chamber 92 and the second hydraulic chamber 93, the entire pressure receiving surface 96 is pressed. In either case, the inner peripheral side of the pressure receiving surface 96 strokes (inner peripheral stroke amount L5).

  Therefore, as in the first and second embodiments, the engagement response can be improved while maintaining a high shift quality without causing a clutch drag phenomenon due to a large reduction in the volume increment ΔV and a deterioration of the shift shock. . Further, variation in shift shock can be reduced. Even during fine engagement control, it is possible to improve responsiveness and reduce variations in fastening timing.

  In this embodiment, the hydraulic chamber to be used can be switched as described above, but switching the hydraulic chamber to be used is nothing other than changing the substantial pressure receiving area of the pressure receiving surface 96. Changing the pressure receiving area also means increasing or decreasing the gain of the transmission torque of the multi-plate clutch 90.

  The gain of the transmission torque is the increment of the transmission torque with respect to the increment of the clutch hydraulic pressure Pc. If other conditions are the same, the gain increases as the pressure receiving area of the pressure receiving surface 96 increases.

  If the gain is too large, the transmission torque will fluctuate more than necessary due to slight fluctuations and variations in the clutch oil pressure Pc, causing adverse effects such as an increase in shift shock. On the other hand, if the gain is too small, the necessary transmission torque cannot be obtained sufficiently, or the fastening timing delay increases. Since any of these causes deterioration of the shift quality, it is desirable that the gain of the transmission torque is within an appropriate range.

  Therefore, in this embodiment, when the required transmission torque is relatively small, only the first hydraulic chamber 92 is pressurized (conversely, the hydraulic pressure may be applied only to the second hydraulic chamber 93), and the gain is lowered to change the shock. Has improved. Also, when performing the fine engagement control, the variation in the stroke amount of the clutch piston 95 with respect to the variation in the clutch hydraulic pressure Pc in the fine engagement state is reduced by reducing the gain. On the other hand, when the required transmission torque is relatively large, hydraulic pressure is applied to both the first hydraulic chamber 92 and the second hydraulic chamber 93 to increase the gain so that an appropriate fastening timing can be obtained with sufficient transmission torque.

  Thus, according to the present embodiment, higher shift quality can be realized by engaging the multi-plate clutch 90 with an appropriate gain according to the required engagement torque. Further, when performing fine engagement control, it is effective to reduce the stroke amount variation of the clutch piston 95 in the fine engagement state by lowering the gain.

  Next, a fourth embodiment according to the present invention will be described. FIG. 7 is a cross-sectional view of the multi-plate clutch 100 in the fourth embodiment. 8 is a cross-sectional view taken along line VIII-VIII in FIG.

  The main difference between the present embodiment and the first embodiment is that an automatic stroke amount adjusting mechanism 80 is provided. The automatic stroke amount adjusting mechanism 80 prevents the difference between the inner circumferential stroke amount L8 and the outer circumferential stroke amount L6 (cone spring deflection amount L7) from exceeding a predetermined value even when the friction material 31 of the clutch disk 30 is worn. It is a mechanism that adjusts automatically.

  The main part of the automatic stroke amount adjusting mechanism 80 is provided by partially cutting the outer peripheral side of the clutch drum 98. The main structure is to guide the pedestal 82 that supports the return spring 45, the pedestal support member 83 that supports the return spring 45, the spring 84 that constantly biases the pedestal support member 83 toward the inner peripheral side, and the pedestal support member 83. In addition, a holder 85 that supports the spring 84, a cover ring 87 that is annularly provided around the clutch drum 98 and holds the holder 85, and the pressing force transmission member 32 are formed integrally with the friction material 31 according to the wear state. And a pressing ring 81 that presses the base support member 83 toward the fastening side.

  7 and 8 partially show the automatic stroke amount adjusting mechanism 80. Therefore, one base support member 83, one spring 84, and one holder 85 are shown. Three sets are provided at equal radial intervals. Each holder 85 is held by one cover ring 87. As shown in FIG. 7, a spline portion 87 a is formed in the cover ring 87, and the spline portion 87 a is fitted to the clutch drum 98 and is fixed integrally with the clutch drum 98 by a snap ring 88.

  The pedestal support member 83 is guided by the holder 85 and is movable in the radial direction within a regulation range of a ratchet portion 86 (shown in FIG. 8) described later. The ratchet portion 86 is provided at the sliding contact portion between the base support member 83 and the holder 85. The ratchet portion 86 does not restrict the movement of the pedestal support member 83 to the outer peripheral side when a force larger than the urging force of the spring 84 is applied from the inner peripheral side to the outer peripheral side of the pedestal support member 83. Each time the amount of movement toward the outer circumference exceeds one pitch of the ratchet portion 86 (a pitch k1 described later), the ratchet portion 86 advances step by step. On the other hand, the movement of the pedestal support member 83 toward the inner peripheral side is possible only within the pitch at which the pedestal support member 83 is present.

  As shown in FIG. 7, on the inner peripheral side of the pedestal support member 83, a sloped portion 83 a that faces the pedestal 82 and is inclined by about 45 degrees with respect to a plane perpendicular to the rotation axis is formed. A slope 82a is formed on the pedestal 82 so as to abut along the slope 83a.

  On the inner peripheral side of the pedestal support member 83, a slope portion 83 b that faces the pressing ring 81 and has an inclination angle similar to that of the slope portion 83 a is formed. In the pressing ring 81, a slope portion 81a having an inclination angle similar to that of the slope portion 82a is formed at a position facing the slope portion 83b.

  The slope portion 83b and the slope portion 81a have a clearance L9 when the clutch piston 20 is released. The clearance L9 is set to be substantially equal to the inner circumferential stroke amount L8 in a state where the friction material 31 is not initially worn.

  Further, an outer peripheral stroke amount restricting portion 82b is formed at a position of the pedestal 82 facing the clutch piston 20. The outer circumferential side stroke amount regulating portion 82b regulates that the outer circumferential side of the clutch piston 20 strokes a predetermined amount (outer circumferential side stroke amount L6) or more, but when the hydraulic pressure acting on the clutch piston 20 is sufficiently large as will be described later, By moving the whole 82 to the fastening side, further strokes are possible.

  Next, the operation of the automatic stroke amount adjusting mechanism 80 will be described. When the clutch piston 20 starts a stroke, first, the clutch piston 20 moves parallel to the fastening side on both the inner peripheral side and the outer peripheral side against the urging force of the return spring 45. At this time, the pedestal 82 presses the pedestal support member 83 toward the fastening side as a support reaction force of the return spring 45. And the base support member 83 is pressed by the outer peripheral side as a component of the pressing force which acts on the slope part 83a. However, since the biasing force of the spring 84 is set to a value sufficiently larger than the pressing force due to the support reaction force of the return spring 45, the base support member 83 does not move to the outer peripheral side.

  When the stroke amount of the clutch piston 20 reaches the outer circumferential side stroke amount L6, the clutch piston 20 directly contacts and presses the outer circumferential side stroke amount regulating portion 82b of the base 82.

  Further, when the stroke on the inner peripheral side of the clutch piston 20 progresses and reaches the vicinity of the final stage, the inclined surface portion 81a of the pressing ring 81 provided integrally with the pressing force transmitting member 32 becomes the inclined surface portion 83b of the base support member 83. Approach and abut.

  In the initial setting, the outer circumferential side stroke amount L8 is set to be the clearance L9. Therefore, even if the stroke of the clutch piston 20 is completed, the inclined surface portion 81a only contacts the inclined surface portion 83a and is not pressed. However, as wear of the friction material 31 progresses, the clearance between the friction material 31 and the plate 35 increases, so that the outer peripheral stroke amount L8 becomes longer. Accordingly, the slope portion 81a comes into contact with the slope portion 83a in the vicinity of the final stage of the outer stroke and starts to press. Due to the component force of the pressing force, the pedestal support member 83 is moved to the outer peripheral side against the urging force of the spring 84.

  When the friction material 31 has a relatively small amount of wear and the amount of movement of the pedestal support member 83 to the outer peripheral side is less than the pitch k1 of the ratchet portion 86, the spring 84 is attached when the clutch piston 20 is released. The base support member 83 returns to the original position by the force.

  However, when the friction material 31 has a relatively large amount of wear and the amount of movement of the pedestal support member 83 toward the outer peripheral side reaches the pitch k1 of the ratchet portion 86, the ratchet portion 86 advances one step. When the ratchet portion 86 advances one step, when the clutch piston 20 is released, the pedestal support member 83 returns to the outer peripheral side by a pitch k1 from the original position. Accordingly, the clearance L9 is enlarged by the pitch k1. Further, since the pedestal 82 moves to the fastening side by the pitch k1 along the inclined surface 82a by the movement of the pedestal support member 83, the outer circumferential side stroke amount L6 is also increased by the pitch k1.

  The advancement of the ratchet portion 86 is repeated in accordance with the progress of wear of the friction material 31, and the outer peripheral stroke amount L6 and the clearance L9 are sequentially increased stepwise.

  FIG. 9 is a conceptual diagram showing the relationship between the friction material wear amount tw, the outer peripheral stroke amount L6, the disc spring deflection amount L7, the inner peripheral stroke amount L8, and the clearance L9. The horizontal axis indicates the friction material wear amount tw, and the vertical axis indicates the length of each stroke amount. However, in order to make the drawing easy to see, the friction material wear amount tw and the pitch k1 are exaggerated with respect to other lengths.

  As described above, as the friction material wear amount tw increases, the inner circumferential stroke amount L8 also increases. Since the disc spring deflection amount L7 = inner peripheral side stroke amount L8−outer peripheral side stroke amount L6, the automatic stroke amount adjusting mechanism 80 is not used, and the outer peripheral side stroke amount is constant (L6 ′ indicated by a two-dot difference line in FIG. 9). ), The amount of disc spring deflection L7 increases as the inner stroke L8 increases. For example, when the friction material wear amount tw = tw1, the disc spring deflection L7 '= (distance X4-X1), which is larger than the initial value (distance X2-X1).

  However, according to the automatic stroke amount adjusting mechanism 80, the outer peripheral stroke amount L6 increases step by step in accordance with the friction material wear amount tw. It does not increase beyond the pitch k1 of the ratchet portion 86 than -X1). For example, when the friction material wear amount tw = tw1, the disc spring deflection amount L7 = (distance X4-X3), which is smaller than (distance X2-X1 + k1).

  As described above, according to the automatic stroke amount adjusting mechanism 80, it is possible to eliminate the influence caused by the difference between the inner peripheral stroke amount and the outer peripheral stroke amount being excessively increased due to wear of the friction material 31. For example, if the stroke difference between the inner and outer peripheries is excessively increased, the internal stress of the disc spring member 22 may increase. However, according to the automatic stroke amount adjusting mechanism 80, such an increase in stress is suppressed as much as possible. be able to.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention described in the claims.

  For example, the multi-plate clutches 10, 90 and 100 of the above embodiment are all multi-plate clutches that intermittently transmit torque between the turbine shaft 3 and the sun gear extension 50, but are provided between other members to provide torque. You may apply to the multiplate clutch which interrupts transmission. Further, for example, a fixed object such as a transmission case may be used in place of the clutch drum 11, and the sun gear extension 50 may be applied to a multi-plate brake that switches between being rotatable or a fixed element. An application example corresponding to fine engagement control when the present invention is applied to a multi-plate brake is a hill holder that maintains a stop position so that the vehicle does not move unexpectedly when the foot brake is turned off on a slope. .

  When the disc spring member is divided and configured, it is not limited to three and may be divided into two or four or more. There is an advantage that the structure can be simplified as the number of divisions is smaller (the single disc spring member 62 is the simplest as in the second embodiment). On the other hand, as the number of divisions increases, there is an advantage that the internal stress acting on one disc spring member can be reduced. What is necessary is just to determine a division | segmentation number suitably according to the intensity | strength and shape, the amount of bending, etc. of a disc spring member.

  Further, in the first embodiment in which the disc spring member 22 is divided into three, the return spring 45 is provided, and in the second embodiment in which the disc spring member 22 is not divided, the return spring is not provided. You may decide whether you need a return spring. When the return spring is provided, the disc spring deflection amount L2 with respect to the inner peripheral stroke amount L3 can be shortened, so that there is an advantage that the internal stress of the disc spring member 22 can be reduced. On the other hand, when no return spring is provided, there is an advantage that the number of parts can be reduced and the structure can be simplified.

  The pressing force transmission member 32 is not necessarily provided, and may be appropriately provided according to the layout of each part. For example, when the layout is such that the inner diameter of the clutch piston 20 is in the vicinity of the middle between the inner diameter and the outer diameter of the plate 35, a member (corresponding to the piston boss portion 29) extending from the inner peripheral side of the clutch piston 20 to the plate 35 side. By forming the pressing portion at the tip of the member to be pressed), it is possible to prevent the pressing force transmission member 32 from being provided.

  The balance piston 15 is not necessarily provided. For example, when the clutch drum 11 (or a fixed object such as a transmission case) is a non-rotating member, centrifugal oil pressure is not generated, which is unnecessary. Even if the clutch drum 11 or the like is a rotating member, the balance piston 15 may not be provided by using other centrifugal hydraulic pressure canceling means.

1 is a cross-sectional view showing a multi-plate clutch that is a first embodiment of a friction fastening device according to the present invention and a peripheral portion thereof. It is an expanded sectional view which expands and shows the principal part of FIG. It is explanatory drawing which shows the concept of volume increment of the hydraulic fluid introduce | transduced into a hydraulic chamber. It is a graph which shows the clutch hydraulic pressure characteristic at the time of gear shifting. It is sectional drawing of the multi-plate type clutch which is 2nd Embodiment of the friction fastening apparatus which concerns on this invention. It is sectional drawing of the multi-plate clutch which is 3rd Embodiment of the friction fastening apparatus which concerns on this invention. It is sectional drawing of the multi-plate clutch which is 4th Embodiment of the friction fastening apparatus which concerns on this invention. It is the VIII-VIII sectional view taken on the line of FIG. It is a conceptual diagram which shows the relationship between the abrasion amount of an friction material, the amount of inner peripheral side strokes, the amount of disk spring deflection, the amount of outer peripheral side strokes, and clearance of the multi-plate clutch shown in FIG.

Explanation of symbols

10. Multi-plate clutch (transmission friction fastening device)
11 Clutch drum (Rotating drum)
11a Cylinder part 12 Hydraulic chamber 20 Clutch piston (hydraulic piston)
21 pressure receiving surface 22 disc spring member 22a first disc spring member (a disc spring member disposed on a concentric circle)
22b Second disc spring member (disc spring member disposed concentrically)
22c 3rd disc spring member (a disc spring member arranged on a concentric circle)
25 division seal part (also the inner circumference side seal part)
26 Inner peripheral side seal portion 27 Outer peripheral side seal portion 30 Clutch disc (friction disc)
32 pressing force transmission member 32b pressing portion 35 plate 46a outer circumferential side stroke amount regulating portion (outer circumferential side stroke amount regulating member)
60 Clutch piston (hydraulic piston)
61 pressure-receiving surface 62 disc spring member 65 snap ring (outer peripheral side locking member)
80 Automatic stroke adjustment mechanism 90 Multi-plate clutch (Friction fastening device for transmission)
91a Cylinder portion 92 First hydraulic chamber (partitioned hydraulic chamber)
93 Second hydraulic chamber (partitioned hydraulic chamber)
94a First drum (part of rotating drum)
94b Second drum (part of rotating drum)
95 Clutch piston 96 Pressure receiving surface 100 Multi-plate clutch (friction fastening device for transmission)
L1, L6 Outer peripheral stroke amount L3, L4, L5, L8 Inner peripheral stroke amount

Claims (7)

A plurality of friction disks and plates arranged alternately so that their plate surfaces face each other;
A cylinder portion whose axial direction is the direction in which the friction disks and plates are arranged; and
A hydraulic chamber formed in the cylinder part;
A hydraulic piston which is provided in the cylinder part and receives the hydraulic pressure of the hydraulic chamber on a pressure receiving surface formed between the outer peripheral side seal part and the inner peripheral side seal part, and strokes in the axial direction of the cylinder part;
In the friction fastening device for a transmission, which includes a pressing portion that presses the friction disk and the plate when the hydraulic piston strokes.
The pressing portion and the inner peripheral side of the hydraulic piston move integrally with the same stroke ,
A friction fastening device for a transmission, wherein an outer peripheral stroke amount of the pressure receiving surface of the hydraulic piston is configured to be shorter than the pressing portion and an inner peripheral stroke amount. The pressure receiving surface is constituted by a disc spring member,
2. The frictional engagement device for a transmission according to claim 1, further comprising an outer circumferential side stroke amount regulating member for regulating an outer circumferential side stroke amount of the disc spring member within a predetermined value shorter than an inner circumferential side stroke amount. The pressure receiving surface is constituted by a disc spring member,
2. The friction fastening device for a transmission according to claim 1, further comprising an outer peripheral side locking member that locks the outer peripheral side stroke of the disc spring member so as to regulate the stroke. An inner diameter of the friction disk and the plate is larger than an inner diameter of the hydraulic piston,
4. The friction fastening device for a transmission according to claim 2, further comprising a pressing force transmission member that integrally connects the inner peripheral side of the hydraulic piston and the pressing portion.   5. The friction fastening device for a transmission according to claim 2, wherein the disc spring member is formed by concentrically arranging a plurality of disc springs having different inner and outer diameters. 6.   6. A partition seal portion for partitioning the hydraulic chamber into a plurality of hydraulic chambers is provided between the outer peripheral seal portion and the inner peripheral seal portion of the pressure receiving surface. The frictional engagement device for a transmission according to any one of the above.   An automatic stroke amount adjusting device is provided that automatically adjusts so that the difference between the inner peripheral stroke amount and the outer peripheral stroke amount does not exceed a predetermined value even if the friction material of the friction disk is worn. The frictional engagement device for a transmission according to any one of claims 1 to 6.

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