JP2009103281A - Power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power transmission device capable of avoiding excessive torque from being transmitted from a driven side rotation shaft to a drive side rotation shaft. <P>SOLUTION: The power transmission device 1 is provided with a clutch outer 10 connected to the drive side rotation shaft; a clutch inner 11 connected to the driven side rotation shaft 3; and a plurality of clutch discs 12 arranged so as to be superposed on each other between the clutch outer 10 and the clutch inner 11 and alternately fixed to the clutch outer 10 or the clutch inner 11, and transmits torque between the drive side rotation shaft and the driven side rotation shaft 3 by engaging the plurality of clutch discs 12 with each other. The device 1 is further provided with a one-way clutch 13 interposed between the driven side rotation shaft 3 and the clutch inner 11 and idle-turned when the number of revolution of the driven side rotation shaft 3 exceeds the number of revolution of the clutch outer 10; and a viscous coupling 14 interposed between the driven side rotation shaft 3 and the clutch inner 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power transmission device that transmits torque between a drive side rotary shaft and a driven side rotary shaft.

  For example, in a motorcycle or the like, when a sudden downshift is performed during traveling, the rotation of the rear tire due to the inertia of the vehicle body and the rotation of the engine are not synchronized, and the torque from the rear tire (generally “back torque”) Is transmitted to the engine. In that case, popping may occur in the rear tire, resulting in a decrease in riding comfort, and the rear tire may be locked and fall down. And in the case of a shaft drive, a malfunction may arise in a differential or a propeller shaft. As a countermeasure against such back torque, a back torque limiter is known in which connection of a clutch is adjusted to avoid an excessive back torque being transmitted to the engine side (see, for example, Patent Document 1).

  The back torque limiter disclosed in Patent Document 1 is arranged such that a clutch outer connected to an engine crankshaft, a clutch inner connected to an input shaft of a transmission, and the clutch outer and the clutch inner overlap each other. And a plurality of clutch disks held alternately by the clutch outer or the clutch inner, and a pressure plate for pressing the plurality of clutch disks in the overlapping direction thereof.

  The plurality of clutch disks are frictionally engaged with each other by being pressed by the pressure plate, whereby the crankshaft and the input shaft are connected, and torque is transmitted between them. On the other hand, when the pressing by the pressure plate is released, the clutch disc is released from the frictional engagement, whereby the crankshaft and the input shaft are disconnected, and the transmission of torque between them is interrupted.

  In this back torque limiter, the clutch inner is divided into a main clutch inner connected to the input shaft and a sub-clutch inner holding the clutch disk. The main clutch inner is configured to sandwich a clutch disk between the pressure plate and the main clutch inner. The sub-clutch inner is axially displaceable with respect to the main clutch inner, and is normally urged toward the main clutch inner and integrated with the main clutch inner.

The back torque limiter includes back torque releasing means for moving the sub clutch inner toward the pressure plate. The back torque releasing means moves the sub clutch inner to the pressure plate side when the back torque is input to the input shaft. Accordingly, the pressure plate is pressed by the sub-clutch inner in a direction opposite to the pressing direction in which the clutch disk is frictionally engaged. As a result, the frictional engagement of the clutch disk is weakened, and it is avoided that slippage occurs and excessive back torque is transmitted from the input shaft to the crankshaft.
JP 2000-55086 A

  In the back torque limiter disclosed in Patent Document 1, there are many movable parts such as a sub-clutch inner that can be displaced relative to the main clutch inner in the axial direction, and the sub-clutch inner is biased toward the main clutch inner. A mechanism for driving a movable portion such as an urging unit that performs this operation and a back torque release unit that moves the sub-clutch inner to the pressure plate side is also required. As described above, the back torque limiter disclosed in Patent Document 1 has a complicated structure, tends to increase in the number of parts, and becomes large. In consideration of mounting on a motorcycle or the like in which the mounting volume of the device is limited, it is desirable that the back torque limiter be small.

  The present invention has been made in view of the above-described circumstances, and provides a power transmission device that can avoid an excessive torque from being transmitted from a driven side rotating shaft to a driving side rotating shaft with a simple configuration. The purpose is to do.

Said objective is achieved by the power transmission device as described in the following (1) to (2).
(1) A clutch outer connected to the drive side rotating shaft, a clutch inner connected to the driven side rotating shaft, and an overlap between the clutch outer and the clutch inner, and alternately arranged between the clutch outer or the clutch outer And a plurality of clutch disks held by a clutch inner, wherein the plurality of clutch disks are engaged with each other to transmit torque between the driving side rotating shaft and the driven side rotating shaft. A one-way clutch that is interposed between the driven-side rotary shaft and the clutch inner and that idles when the rotational speed of the driven-side rotary shaft exceeds the rotational speed of the clutch outer; and the driven-side rotary shaft And a viscous coupling interposed between the clutch inner and the clutch inner.
(2) The power transmission device according to (1), which is a back torque limiter interposed between an engine and a transmission of a motorcycle.

  According to the power transmission device of the present invention, the one-way clutch and the viscous coupling are provided between the driven side rotating shaft and the clutch inner. If the rotational speed of the driven-side rotary shaft is equal to or lower than the rotational speed of the clutch outer, the driven-side rotary shaft and the clutch inner are mechanically connected via a one-way clutch to rotate integrally, and the clutch outer, clutch disc, clutch Torque is transmitted between the drive side rotary shaft and the driven side rotary shaft via the inner and the one-way clutch in sequence. On the other hand, when the rotational speed of the driven side rotating shaft exceeds the rotational speed of the clutch outer, the one-way clutch rotates idly, and the driven side rotating shaft and the clutch inner are connected via a viscous coupling. In this case, torque is transmitted between the driven side rotating shaft and the clutch inner by the viscous fluid of the viscous coupling. The torque transmission characteristics of viscous couplings with viscous fluid are generally such that the torque transmitted in response to an increase in the difference in rotational speed between the driven rotary shaft and the clutch inner increases. Then, the transmitted torque is saturated. Thereby, it is possible to avoid an excessive torque being transmitted from the driven side rotating shaft to the driving side rotating shaft. By using the viscous coupling having the torque transmission characteristics as described above, torque can be transmitted smoothly without performing fine control. Furthermore, the one-way clutch and viscous coupling are not relatively displaced in the axial direction with respect to the driven-side rotary shaft or clutch inner, but the number of movable parts is reduced to simplify the configuration of the power transmission device and reduce its size. Can be planned. Such a power transmission device can be suitably used as a back torque limiter in a motorcycle.

  Hereinafter, preferred embodiments of a power transmission device according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment of a power transmission device according to the present invention.

  As shown in FIG. 1, the power transmission device of the present embodiment is a back torque limiter interposed between an engine and a transmission of a motorcycle, for example. The back torque limiter 1 transmits torque between an engine crankshaft (not shown), which is a driving side rotation shaft, and an input shaft 3 of a transmission, which is a driven side rotation shaft.

  The back torque limiter 1 includes a clutch outer 10 connected to the crankshaft, a clutch inner 11 connected to the input shaft 3, and a plurality of the clutch outer 10 and the clutch inner 11 that are arranged to overlap each other. And a clutch disk 12.

  A hub 20 is fixed to one end of the input shaft 3 so as not to rotate relative to the input shaft 3 by appropriate means such as spline fitting. The clutch inner 11 is rotatably supported on the input shaft 3 by interposing a bearing between the clutch inner 11 and the hub 20 or loosely fitting the hub 20.

  The clutch outer 10 is rotatably supported by a housing, for example, with a bearing interposed between the back torque limiter 1 and a housing (not shown). A large gear 5 that meshes with the small gear 4 fixed to the crankshaft is joined to one end of the clutch outer 10 and is connected to the crankshaft via these gears 4 and 5.

  The clutch outer 10 includes a clutch inner 11 and is disposed coaxially with the clutch inner 11. An accommodating space 25 for accommodating the plurality of clutch disks 12 is formed between the clutch outer 10 and the clutch inner 11.

  The plurality of clutch disks 12 are disposed in parallel with each other in the housing space 25 so as to overlap in the axial direction, and are alternately held by the clutch outer 10 or the clutch inner 11. That is, each clutch disk 12a held by the clutch outer 10 is disposed at a predetermined interval in the axial direction, and each clutch disk held by the clutch inner 11 is located between adjacent clutch disks 12a and 12a. 12b is arranged. The clutch disks 12a held by the clutch outer 10 can be displaced relative to the clutch outer 10 in the axial direction while maintaining a distance from each other.

  The accommodating space 25 is open toward one side in the axial direction, and an annular pressure plate 6 is disposed facing the opening. The pressure plate 6 is supported so as to be movable in the axial direction by a plurality of guide pins 23 that pass through the inner periphery of the pressure plate 6 and are fixed to the clutch inner 11. A clutch spring 24 is interposed between the pressure plate 6 and the base end portion of the guide pin 23, and the pressure plate 6 is urged toward the accommodation space 25 by the clutch spring 24.

  In the arrangement of the plurality of clutch disks 12, the clutch disk 12 a held by the clutch outer 10 is positioned at the opening side end of the accommodation space 25, and this clutch disk 12 a is exposed through the opening of the accommodation space 25. . The pressure plate 6 biased by the clutch spring 24 presses the clutch disk 12a located at the end. The pressure plate 6 is driven toward the side opposite to the housing space 25 against the clutch spring 24 by operating a clutch lever (not shown).

  When the clutch disk 12a located at the end is pressed by the pressure plate 6, the clutch disks 12a held by the clutch outer 10 are displaced in the axial direction while maintaining a mutual interval. Thus, each clutch disk 12 a held by the clutch outer 10 is frictionally engaged with the clutch disk 12 b held by the clutch inner 11. When the pressure plate 6 is driven toward the side opposite to the accommodating space 25, the clutch disk 12a located at the end is released from the pressure by the pressure plate 6, and the clutch disks 12a are pressed at a distance from each other. It is displaced in the axial direction opposite to the time, and the frictional engagement between each clutch disk 12a and clutch disk 12b is released. The clutch outer 10 and the clutch inner 11 rotate together with the clutch disks 12a and the clutch disks 12b frictionally engaged with each other.

  The back torque limiter 1 includes a one-way clutch 13 that can connect the input shaft 3 and the clutch inner 11. The one-way clutch 13 is interposed between the hub 20 fixed to the input shaft 3 and the clutch inner 11.

  The one-way clutch 13 is locked when the rotational speed of the driven-side input shaft 3 is equal to or lower than the rotational speed of the driving-side clutch outer 10, and connects the input shaft 3 and the clutch inner 11. When the rotational speed of the driven-side input shaft 3 is equal to or lower than the rotational speed of the driving-side clutch outer 10, torque is transmitted from the driving side to the driven side. The torque at that time is transmitted from the crankshaft 2 to the input shaft 3 through the clutch outer 10 and the clutch inner 11 that rotate together, and through the one-way clutch 13.

  On the other hand, when the rotational speed of the driven-side input shaft 3 exceeds the rotational speed of the driving-side clutch outer 10, the one-way clutch 13 rotates idly and the clutch inner 11 can rotate relative to the input shaft 3. As a result, torque transmission between the clutch inner 11 and the input shaft 3 via the one-way clutch 13 is cut off.

  Here, when the rotational speed of the driven input shaft 3 exceeds the rotational speed of the clutch outer 10 on the driving side, back torque transmitted from the driven side to the driving side is generated. The transmission of torque via is interrupted as described above. That is, no back torque is transmitted from the input shaft 3 to the crankshaft via the one-way clutch 13, but at the same time, the deceleration action by the rotational resistance of the driving side such as the engine brake is driven via the one-way clutch 13. Will not be transmitted at all.

  Therefore, the back torque limiter 1 includes a viscous coupling 14 that connects between the input shaft 3 and the clutch inner 11. The viscous coupling 14 includes a plurality of inner members in a working chamber 30 formed in a sealed state using a pair of oil seals 21 and 22 between the hub 20 fixed to the input shaft 3 and the clutch inner 11. A plate 31 and an outer plate 32 are provided and generally configured.

  Each inner plate 31 is fixed to the outer peripheral surface of the hub 20 facing the working chamber 30 and rotates together with the hub 20. Each outer plate 32 is fixed to the inner peripheral surface of the clutch inner 11 facing the working chamber 30 and rotates together with the clutch inner 11. The inner plate 31 and the outer plate 32 are arranged in parallel with each other so as to overlap each other in the axial direction so that the outer plate 32 enters between the adjacent inner plates 31 and 31.

  The working chamber 30 is filled with a viscous fluid such as silicon oil, and the viscous fluid is interposed between the inner plate 31 and the outer plate 32 adjacent to each other. When a rotational speed difference occurs between the inner plate 31 and the outer plate 32, that is, when a rotational speed difference occurs between the input shaft 3 and the clutch inner 11, the viscosity between the inner plate 31 and the outer plate 32 is increased. The fluid is sheared. Torque is transmitted between the inner plate 31 and the outer plate 32, and thus between the input shaft 3 and the clutch inner 11, due to the shearing resistance of the viscous fluid at this time.

  When the rotational speed of the driven-side input shaft 3 exceeds the rotational speed of the driving-side clutch outer 10, the one-way clutch 13 idles and the clutch inner 11 rotates together with the clutch outer 10, and the input shaft 3 and the clutch A rotational speed difference is generated between the inner 11 and the inner 11. Accordingly, torque is transmitted between the input shaft 3 and the clutch inner 11 via the viscous coupling 14.

  Here, the transmission characteristic of the torque due to the viscous fluid of the viscous coupling 14 is generally that the rotational speed difference between the inner plate 31 and the outer plate 32, that is, the rotational speed difference between the input shaft 3 and the clutch inner 11 becomes large. Correspondingly, the transmitted torque increases, but the transmitted torque is saturated at a rotational speed difference of a predetermined value or more. Therefore, it is avoided that an excessive back torque is transmitted from the input shaft 3 to the crankshaft.

  Even when the rotational speed of the driven-side input shaft 3 exceeds the rotational speed of the driving-side clutch outer 10, torque transmission between the input shaft 3 and the clutch inner 11 is maintained via the viscous coupling 14. Therefore, the deceleration action by the rotational resistance on the driving side such as engine brake is appropriately transmitted to the driven side.

  As described above, according to the back torque limiter 1 of the present embodiment, the one-way clutch 13 and the viscous coupling 14 are provided between the input shaft 3 and the clutch inner 11. If the rotational speed of the input shaft 3 is less than or equal to the rotational speed of the clutch outer 10, the input shaft 3 and the clutch inner 11 are mechanically connected via a one-way clutch 13 and rotate together. 12, torque is transmitted between the crankshaft and the input shaft 3 via the clutch inner 11 and the one-way clutch 13. On the other hand, when the rotational speed of the input shaft 3 exceeds the rotational speed of the clutch outer 10, the one-way clutch 13 rotates idly and the input shaft 3 and the clutch inner 11 are connected via the viscous coupling 14. In this case, torque is transmitted between the input shaft 3 and the clutch inner 11 by the viscous fluid of the viscous coupling 14. The torque transmission characteristic of viscous coupling viscous fluid generally increases the torque transmitted in response to an increase in the rotational speed difference between the input shaft 3 and the clutch inner 11, but the rotational speed difference exceeds a predetermined value. The torque transmitted by saturates. Thereby, it is possible to avoid an excessive torque being transmitted from the input shaft 3 to the crankshaft. By using the viscous coupling 14 having the torque transmission characteristics as described above, torque can be transmitted smoothly without performing fine control. Further, the one-way clutch 13 and the viscous coupling 14 are not displaced relative to the input shaft 3 or the clutch inner 11 in the axial direction, and the configuration of the back torque limiter 1 is simplified by reducing the movable parts. Miniaturization can be achieved.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimension, numerical value, form, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved. For example, in the above-described embodiment, the power transmission device according to the present invention has been described by taking the back torque limiter mounted on the motorcycle as an example, but the present invention is not limited to this.

It is sectional drawing of one Embodiment of the power transmission device which concerns on this invention.

Explanation of symbols

1 Back torque limiter (power transmission device)
3 Input shaft (driven shaft)
10 Clutch outer 11 Clutch inner 12 Clutch disc 13 One-way clutch 14 Viscous coupling

Claims (2)

A clutch outer coupled to the drive-side rotation shaft;
A clutch inner coupled to the driven side rotating shaft;
A plurality of clutch discs arranged to overlap between the clutch outer and the clutch inner, and alternately held by the clutch outer or the clutch inner;
With
A power transmission device for engaging the plurality of clutch disks with each other to transmit torque between the drive-side rotary shaft and the driven-side rotary shaft;
A one-way clutch that is interposed between the driven-side rotary shaft and the clutch inner, and idles when the rotational speed of the driven-side rotary shaft exceeds the rotational speed of the clutch outer;
A viscous coupling interposed between the driven rotary shaft and the clutch inner;
The power transmission device further comprising:   The power transmission device according to claim 1, wherein the power transmission device is a back torque limiter interposed between an engine and a transmission of the motorcycle.

Images