Power transmission device

Abstract

To provide a power transmission device capable of suppressing vibration of a chain, while improving durability of the chain and a vibration suppression member by reducing sliding resistance between the chain and the vibration suppression member.SOLUTION: A power transmission device 3 has a sprocket 19 for vibration suppression between a sprocket 14 and a sprocket 15. The sprocket 19 meshes with a tension side of a silent chain 16, and rotates as the silent chain 16 moves around.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power transmission device. [Background technology]

[0002] When power is transmitted by a chain wound around a rotating body, vibration of the chain occurs. Conventionally, a chain guide described in Patent Document 1 is known as a device for suppressing chain vibration.

[0003] The chain guide described in Patent Document 1 comprises a guide shoe that slides and guides the chain as it runs around multiple sprockets, and a base member that supports the guide shoe along the chain running direction. By stabilizing the chain running between the sprockets and maintaining appropriate tension, the chain vibration is suppressed.

[0004] Furthermore, a power transmission device described in Patent Document 2 is known that focuses on the string vibration of the chain and suppresses the string vibration of the chain.

[0005] This power transmission device includes an opposing member having an opposing portion that faces the circumferential surface of the chain between a pair of sprockets, and an adjustment mechanism that can adjust the position of the opposing member in accordance with the number of revolutions of the chain so that the opposing portion is positioned at the antinode position of the vibration mode in the string resonance of the chain. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-177988 [Patent Document 2] Japanese Patent Application Publication No. 2018-162827 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the chain guide described in Patent Document 1, the chain guide contacts and presses against the chain over a wide area, which generates sliding resistance between the chain and the chain guide, causing wear on the chain and chain guide and reducing durability, as well as increasing power loss in the drive unit.

[0008] Furthermore, in the power transmission device described in Patent Document 2, the opposing member abuts against the chain, which generates sliding resistance between the chain and the opposing member, causing wear on the chain and the opposing member, reducing durability, and increasing power loss in the drive device.

[0009] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a power transmission device that can suppress chain vibration while reducing the sliding resistance between the chain and the vibration damping member, thereby improving the durability of the chain and the vibration damping member. [Means for solving the problem]

[0010] The present invention is a power transmission device having a chain that is wound around one sprocket and another sprocket and transmits power between the one sprocket and the other sprocket, characterized in that a vibration damping member is provided between the one sprocket and the other sprocket, and the vibration damping member engages with the tension side of the chain and rotates as the chain moves around. [Effects of the Invention]

[0011] As described above, according to the present invention, a rotating sprocket is used as the chain vibration damping member, which reduces the sliding resistance between the chain and the vibration damping member, improving the durability of the chain and the vibration damping member while suppressing chain vibration. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a power transmission device according to an embodiment of the present invention. [Figure 2]FIG. 2 is a left side view of a transfer device provided in a power transmission device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a view taken along the line III-III in FIG. 2, showing the state in which the tension side (chain portion 16C side) of the silent chain is tightly engaged with the sprocket. [Figure 4] FIG. 4 corresponds to a view seen in the direction of the arrows III-III in FIG. 2, and shows the state in which the tension side (chain portion 16D side) of the silent chain is tightly engaged with the sprocket. DETAILED DESCRIPTION OF THE INVENTION

[0013] A power transmission device according to one embodiment of the present invention is a power transmission device having a chain that is wound around one sprocket and another sprocket and transmits power between the one sprocket and the other sprocket, and a vibration damping member is provided between the one sprocket and the other sprocket, and the vibration damping member engages with the tension side of the chain and rotates as the chain moves around.

[0014] As a result, the power transmission device according to one embodiment of the present invention can reduce the sliding resistance between the chain and the vibration damping member, improving the durability of the chain and the vibration damping member, while also suppressing vibration of the chain. [Example]

[0015] A power transmission device according to an embodiment of the present invention will now be described with reference to the drawings. 1 to 4 are diagrams showing a power transmission device according to one embodiment of the present invention.

[0016] In Figures 1 to 4, the up / down, front / rear, left / right directions are based on the power transmission device when installed in a vehicle, and the front / rear direction of the vehicle is the front-rear direction, the left / right direction of the vehicle (vehicle width direction) is the left / right direction, and the up / down direction of the vehicle (vehicle height direction) is the up / down direction.

[0017] First, the configuration will be described. In FIG. 1, a vehicle 1 includes an engine 2 and a power transmission device 3, and the power of the engine 2 is transmitted via the power transmission device 3 to front wheels 21L, 21R and rear wheels 22L, 22R to run the vehicle.

[0018] The engine 2 is an internal combustion engine that is driven by burning fuel, and is disposed longitudinally at the front of the vehicle 1 in a rearward tilted position.

[0019] The power transmission device 3 includes a transmission 4, a first propeller shaft 5, a transfer device 6, a second propeller shaft 7, a third propeller shaft 8, a rear differential 9, and a front differential 10.

[0020] The transmission 4 is connected to the rear end of the engine 2, and outputs the power (rotational speed) input from the engine 2 after changing the speed using a transmission mechanism (not shown). The transmission 4 may be configured as either an automatic transmission or a manual transmission.

[0021] A transfer device 6 is connected to the rear of the transmission 4 via a first propeller shaft 5. The power of the engine 2 is transmitted to the transfer device 6 via the first propeller shaft 5.

[0022] The transfer device 6 is connected to a second propeller shaft 7 that transmits power to the rear wheels 22L, 22R, and a third propeller shaft 8 that transmits power to the front wheels 21L, 21R.

[0023] The second propeller shaft 7 and the third propeller shaft 8 are arranged coaxially, and are arranged at positions offset from the first propeller shaft 5 in the vehicle width direction.

[0024] The rear end of the second propeller shaft 7 is connected to the rear differential 9. The rear differential 9 is provided between the rear wheels 22L, 22R, and transmits power from the second propeller shaft 7 to the left and right rear wheels 22L, 22R while allowing differential motion.

[0025] The front end of the third propeller shaft 8 is connected to a front differential 10. The front differential 10 is provided between the front wheels 21L, 21R, and transmits power from the third propeller shaft 8 to the left and right front wheels 21L, 21R while allowing differential motion.

[0026] As shown in FIG. 2, the transfer device 6 has a transfer case 11, which has a front case 12 and a rear case 13 connected to the rear of the front case 12.

[0027] The front case houses a two-wheel / four-wheel switching mechanism (not shown). The rear case 13 is provided with sprockets 14 and 15, and a silent chain 16 is wound around the sprockets 14 and 15 (see FIG. 3).

[0028] In this embodiment, the sprocket 14 constitutes one sprocket, and the sprocket 15 constitutes the other sprocket. The silent chain 16 constitutes the chain.

[0029] As shown in Figure 3, the sprocket 14 is fixed to the input shaft 17 and rotates integrally with the input shaft 17. The first propeller shaft 5 is connected to the input shaft 17, and the power of the engine 2 is transmitted from the first propeller shaft 5 and the input shaft 17 to the sprocket 14. As a result, the sprocket 14 is rotated by the engine 2.

[0030] The sprocket 15 is fixed to the output shaft 18 and rotates integrally with the output shaft 18. The second propeller shaft 7 is connected to the output shaft 18, and the power of the sprocket 14 is transmitted to the sprocket 15 via a silent chain 16.

[0031] That is, the power of the engine 2 is transmitted from the first propeller shaft 5, input shaft 17, and sprocket 14 via the silent chain 16 and sprocket 15 to the output shaft 18, and then transmitted from the output shaft 18 to the left and right rear wheels 22L, 22R via the second propeller shaft 7 and rear differential 9. This allows the vehicle 1 to travel in two-wheel drive.

[0032] A third propeller shaft 8 is connected to the output shaft 18 via a two-wheel / four-wheel switching mechanism. The two-wheel / four-wheel switching mechanism can be switched between a two-wheel drive position and a four-wheel drive position by a driver's switching operation.

[0033] When the two-wheel / four-wheel changeover mechanism is switched to the four-wheel drive position, not only the output shaft 18 and the second propeller shaft 7 but also the output shaft 18 and the third propeller shaft 8 are connected.

[0034] At this time, the power of the engine 2 is transmitted from the input shaft 17 via the sprocket 14, the silent chain 16, the sprocket 15, and the output shaft 18 to the third propeller shaft 8, and then transmitted from the third propeller shaft 8 to the front wheels 21L, 21R via the front differential 10. This allows the vehicle 1 to travel in four-wheel drive mode.

[0035] In two-wheel drive, the driver switches the two-wheel / four-wheel switching mechanism to the two-wheel drive position, mechanically disconnecting the third propeller shaft 8 from the output shaft 18. This prevents the power of the engine 2 from being transmitted from the output shaft 18 to the third propeller shaft 8.

[0036] A vibration-suppressing sprocket 19 is housed in the rear case 13. The sprocket 19 is attached to a rotating shaft 20 and rotates integrally with the rotating shaft 20. The front end of the rotating shaft 20 is rotatably supported by the front case 12 via a bearing (not shown), and the rear end of the rotating shaft 20 is rotatably supported by the rear case 13 via a bearing (not shown). The sprocket 19 in this embodiment constitutes a vibration-suppressing member.

[0037] The sprocket 19 is disposed inside the silent chain 16 and engages with both the tight side and the slack side of the silent chain 16.

[0038] Specifically, sprocket 19 has a larger diameter than sprockets 14 and 15, and the tips of the teeth of sprocket 19 that mesh with silent chain 16 protrude outward from two common tangents 21 and 22 to the outer diameter circles of sprockets 14 and 15. Meshing portion 19a of sprocket 19 that meshes with silent chain 16 is positioned outward from two common tangents 21 and 22 to the outer diameter circles of sprockets 14 and 15.

[0039] By positioning the tooth tips of sprocket 19 outward from the two common tangents 21, 22 of sprockets 14, 15, meshing portion 19a of sprocket 19 meshes with both the tight side and the slack side of silent chain 16. As a result, silent chain 16 is positioned so that the center portion of silent chain 16 between sprocket 14 and sprocket 15 bulges outward.

[0040] In other words, the sprocket 19 engages with the silent chain 16 from the inside to push the silent chain 16 outward.

[0041] The silent chain 16 comprises a number of meshing link plates 16A, each having a pair of teeth 16a and a pair of pin holes 16b, and connecting link plates 16B that connect adjacent meshing link plates 16A. Note that link plates 16B also have a pair of teeth 16a and a pair of pin holes 16b, and are shaped similarly to link plates 16A.

[0042] The connecting link plate 16B is connected to the mating link plate 16A by a connecting pin inserted into the pin hole 16b of the mating link plate 16A. The link plate 16B connects the link plates 16A to each other.

[0043] The silent chain 16 is endlessly wound around the sprockets 14, 15, and 19, and the teeth 16a of the link plates 16A mesh with the teeth of the sprockets 14, 15, and 19, and moves in circles as the sprockets 14 and 15 rotate.

[0044] When each link plate 16A of the silent chain 16 enters the teeth of the sprockets 14, 15, and 19, the tooth portions 16a of the link plates 16A come into contact with and mesh with the teeth of the sprockets 14, 15, and 19.

[0045] When the chain is wound around the sprockets 14, 15, and 19, the meshing link plate 16A bends relative to the connecting link plate 16B, causing the tooth portions 16a, which are arranged adjacent to each other in the axial direction of the connecting pin and fit between the same teeth of the sprockets 14, 15, and 19, to spread in the winding direction (circumferential direction of the sprockets 14, 15, and 19) and repeatedly come into close contact with the teeth of the sprockets 14, 15, and 19, eliminating any backlash and making the chain quieter than a roller chain.

[0046] The ability of this silent chain 16 to fit tightly onto the teeth of sprockets 14, 15, and 19 depends on the bending angle of link plates 16A and 16B, so at the meshing portion 19a with sprocket 19, which has a relatively small bending angle, the spread of tooth portion 16a is relatively small and the ability of silent chain 16 to fit tightly onto the teeth of sprocket 19 is minimal, resulting in a relatively loose meshing with gaps and play.

[0047] Next, the effects of the power transmission device 3 of this embodiment will be described. Whether the vehicle 1 is in two-wheel drive or four-wheel drive mode, the power of the engine 2 is transmitted from the input shaft 17 to the sprocket 15 via the sprocket 14 and silent chain 16. When the vehicle 1 moves forward, the input shaft 17 and the output shaft 18 rotate clockwise in FIG.

[0048] At this time, the sprocket 14 provided on the input shaft 17 becomes the driving side, and the sprocket 15 provided on the output shaft 18 becomes the driven side, and the silent chain 16 moves around clockwise in FIG.

[0049] As a result, the silent chain 16 is pulled by the sprockets 14 as it moves around, so the chain portion 16C located on the upper side between the upstream sprocket 15 and the downstream sprocket 14 is the tight side, and the chain portion 16D located on the lower side between the upstream sprocket 14 and the downstream sprocket 15 in the direction of the silent chain 16's movement is the slack side. The sprocket 19 rotates clockwise as the silent chain 16 moves around.

[0050] On the other hand, when the vehicle 1 traveling forward is decelerating, the power of at least one of the front wheels 21L, 21R and the rear wheels 22L, 22R is transmitted from the output shaft 18 to the sprocket 14 via the sprocket 15 and the silent chain 16.

[0051] At this time, the sprocket 15 provided on the output shaft 18 becomes the driving side, and the sprocket 14 provided on the input shaft 17 becomes the driven side, and the silent chain 16 moves around in a clockwise direction.

[0052] As a result, the silent chain 16 is pulled by the sprockets 14 as it moves around, so the chain portion 16D located on the lower side between the upstream sprocket 14 and the downstream sprocket 15 is the tight side, and the chain portion 16C located on the upper side between the upstream sprocket 15 and the downstream sprocket 14 in the direction of the silent chain 16's movement is the slack side. The sprocket 19 rotates clockwise as the silent chain 16 moves around.

[0053] The silent chain 16 is wound around the sprockets 14, 15 with a relatively loose tension. Therefore, the meshing between the silent chain 16 and the sprocket 19 is different on the tight side and the slack side.

[0054] Specifically, the silent chain 16 has a tight side that deeply meshes with the teeth of the sprocket 19, forming an engagement portion 19a with relatively little freedom (small gap in the direction of circular movement), and a loose side that shallowly meshes with the teeth of the sprocket 19, forming an engagement portion 19a with relatively little freedom (large gap in the direction of circular movement).

[0055] However, when vehicle 1 attempts to accelerate from a slow deceleration state, tension acts on the loosened chain portion 16C, tightening it and adding movement perpendicular to the direction of circular movement, and chain portion 16C becomes the tight side and is subjected to tension, which may cause string vibration in chain portion 16C and generate abnormal noise.

[0056] Conversely, when vehicle 1 attempts to decelerate from an accelerating state, tension acts on the loose chain portion 16D, tightening it and adding movement perpendicular to the direction of circular movement, causing chain portion 16D to become the tight side and be under tension, which may cause string vibration in chain portion 16D and generate abnormal noise.

[0057] In other words, if the silent chain 16 is used to transmit power between shafts that are relatively far apart, there is a risk of string vibration occurring when torque fluctuations cause the slack side to become the tight side.

[0058] The vibration that occurs when the silent chain 16 is switched from the slack side to the tight side is called string vibration, and the vibration of the silent chain 16 on either the tight side or the slack side is called vibration, but string vibration and vibration are also simply referred to as vibration of the silent chain 16.

[0059] The power transmission device 3 of this embodiment has a sprocket 19 for vibration suppression between sprockets 14 and 15, and the sprocket 19 strongly abuts and meshes with the tension side of the silent chain 16, rotating as the silent chain 16 moves around.

[0060] This shortens the vibration length (the length of the loop when vibrating) of the silent chain 16, thereby increasing the resonant frequency, thereby suppressing vibration of the silent chain 16 and reducing the generation of abnormal noise.

[0061] Specifically, when the vehicle 1 accelerates from a slow deceleration state, the loose chain portion 16C becomes taut, adding movement, and when the chain portion 16C becomes taut, the vibration of the chain portion 16C can be suppressed by meshing with the sprocket 19 (see Figure 3).

[0062] On the other hand, when the vehicle 1 decelerates after accelerating, the slack chain portion 16D becomes taut, adding movement and making the chain portion 16D the tight side, and the vibration of the chain portion 16D can be suppressed by meshing with the sprocket 19 (see Figure 4). In other words, even when the tight side changes, one sprocket 19 can handle it.

[0063] Furthermore, because the sprocket 19 rotates while meshing with the silent chain 16, it is possible to reduce the resistance caused by sliding between the sprocket 19 and the silent chain 16, and it is also possible to reduce wear on the sprocket 19 and the silent chain 16. This reduces power loss in the power transmission device 3.

[0064] In this way, the power transmission device 3 of this embodiment can reduce the sliding resistance between the silent chain 16 and the sprocket 19, improving the durability of the silent chain 16 and the sprocket 19, while suppressing vibration of the silent chain 16.

[0065] In addition, in the power transmission device 3 of this embodiment, the diameter and tooth height of the sprocket 19 are set to match the length of the silent chain 16 so that on the tight side of transmitting torque, the tooth portion 16a of the silent chain 16 engages deep into the teeth of the sprocket 19, and on the slack side, the tooth portion 16a only engages with the tips of the teeth of the sprocket 19.

[0066] If the gap between the tooth portion 16a of the silent chain 16 on the slack side and the tooth of the sprocket 19 is small, the accuracy of the installation of the sprocket 19 to the silent chain 16 will be required to the same extent, and the workability of the installation of the silent chain 16 to the sprocket 19 will be reduced.

[0067] This is because the sprocket 19 meshes with both the tight side and the slack side of the silent chain 16 (the forward and return sides in terms of the movement of the silent chain 16).

[0068] In contrast, the power transmission device 3 of this embodiment uses a silent chain 16, so the silent chain 16 meshes with the teeth of the sprocket 19 in a relatively unbent state, allowing the tooth portion 16a to mesh in a relatively unspread state, allowing for a larger gap.

[0069] Furthermore, the slack side spreads outward due to rotation, and the silent chain 16 moves in a direction away from the sprocket 19, allowing for a larger gap.

[0070] This allows a relatively large gap to be secured between the tooth portion 16a of the silent chain 16 on the slack side and the tooth of the sprocket 19, and the mounting precision required for the silent chain 16 on the sprocket 19 can be relaxed to the extent that this gap can be made larger.

[0071] Furthermore, according to the power transmission device 3 of this embodiment, the sprocket 19 is disposed on the inside of the silent chain 16 and engages with both the tight side and the slack side of the silent chain 16.

[0072] This allows the string vibrations on both the tight and loose sides of the silent chain 16 to be suppressed by a single sprocket 19, reducing the number of parts in the vibration suppression sprocket 19 and preventing an increase in the manufacturing costs of the power transmission device 3.

[0073] Furthermore, according to the power transmission device 3 of this embodiment, when the vehicle 1 is traveling forward and sprocket 14 is on the driving side and sprocket 15 is on the driven side, the chain portion 16C that moves from sprocket 15 toward sprocket 14 constitutes the tight side of the silent chain 16, and the chain portion 16D that moves from sprocket 14 toward sprocket 15 constitutes the slack side.

[0074] Furthermore, when the vehicle 1 is traveling forward and sprocket 15 is on the driving side and sprocket 14 is on the driven side, the chain portion 16D that moves from sprocket 14 to the sprocket 15 side constitutes the tight side of the silent chain 16, and the chain portion 16C that moves from sprocket 15 to the sprocket 14 side constitutes the slack side.

[0075] In addition, the sprockets 19 are provided to mesh with the tight and slack sides of the silent chain 16.

[0076] This effectively suppresses string vibration of the tight silent chain 16 even when the tight and slack sides of the silent chain 16 are switched depending on the driving state of the vehicle 1. This reduces the number of parts in the vibration suppression sprocket 19, preventing an increase in the manufacturing cost of the power transmission device 3.

[0077] Furthermore, according to the power transmission device 3 of this embodiment, the sprocket 19 is formed with a larger diameter than the sprockets 14 and 15, and the meshing portion 19a that meshes with the silent chain 16 protrudes outward from the common tangents 21 and 22 of the sprockets 14 and 15.

[0078] Sprocket 19 is disposed approximately in the center between sprockets 14 and 15. More specifically, rotation shaft 20 of sprocket 19 is disposed on a plane including the axis of rotation shaft of sprocket 14 (input shaft 17) and the axis of rotation shaft of sprocket 15 (output shaft 18). In addition, rotation shaft 20 is disposed between the axis of input shaft 17 and the axis of output shaft 18 so as to be parallel to the axis of input shaft 17 and the axis of output shaft 18.

[0079] This allows the silent chain 16 to mesh securely with the sprocket 19, and reliably prevents the silent chain 16 from vibrating.

[0080] Since the silent chain 16 has a tight side and a slack side, vibration suppression sprockets can be provided on both the tight side and the slack side. This increases the number of parts and costs, but it allows for greater freedom in the placement of the vibration suppression sprockets, thereby improving productivity.

[0081] Furthermore, although the chain in this embodiment is configured as a silent chain, it is not limited to a silent chain.

[0082] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0083] 3 Power transmission device 14 sprocket (one sprocket) 15 sprocket (other sprocket) 16 Silent Chain (Chain) 16C, 16D chain section 19 Sprocket (vibration suppression member) 19a Engagement part 21,22 common tangent

Claims

1. A power transmission device having a chain wound around one sprocket and another sprocket to transmit power between the one sprocket and the other sprocket, a vibration damping member is provided between the one sprocket and the other sprocket; The power transmission device is characterized in that the vibration suppressing member engages with the tension side of the chain and rotates as the chain moves around.

2. The vibration damping member is disposed inside the chain, 2. The power transmission device according to claim 1, wherein the tension side and the slack side of the chain are engaged with each other.

3. When the one sprocket is a driving sprocket and the other sprocket is a driven sprocket, a chain portion moving from the other sprocket to the one sprocket constitutes a tight side of the chain, and a chain portion moving from the one sprocket to the other sprocket constitutes a slack side of the chain, When the other sprocket is the driving side and the one sprocket is the driven side, The chain portion moving from the one sprocket to the other sprocket constitutes a tight side, and the chain portion moving from the other sprocket to the one sprocket constitutes a slack side, 3. The power transmission device according to claim 2, wherein the vibration damping member is provided so as to mesh with the tension side and the slack side of the chain.

4. The vibration damping member is formed to have a larger diameter than the one sprocket and the other sprocket, 4. A power transmission device according to claim 1, wherein the meshing portion of the vibration damping member that meshes with the chain protrudes outward beyond a common tangent line between the one sprocket and the other sprocket.

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