Chain transmission device

Abstract

To provide a chain transmission device capable of suppressing local abrasion due to slide contact with a chain plate in a chain guide.SOLUTION: A chain transmission device 10 has a plurality of chain sprockets, an endless chain 15 wound around the plurality of sprocket, and a chain guide 21 that guides the endless chain 15. The chain guide 21 comprises an actuator that is provided so as to be able to reciprocate in a direction intersecting a travel direction of the endless chain 15, and that moves the chain guide 21.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to a chain transmission device.

Background Art

[0002] As a prior art of a chain transmission device, for example, a chain transmission system disclosed in Patent Document 1 is known. The chain transmission system disclosed in Patent Document 1 includes a plurality of sprockets around which a chain is wound, and one or more guides for guiding the chain. The plurality of guides integrally or separately include a guide shoe having a chain running surface, and a part of the chain running surface has a lubricating region holding a solid lubricant. The chain transmission system disclosed in Patent Document 1 reduces the sliding resistance between the chain and the guide shoe, suppresses the increase in sliding resistance over time, and reduces the manufacturing cost.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the chain transmission system disclosed in Patent Document 1, the chain plate passes through the same position with respect to the guide for guiding the chain. For this reason, there is a problem that grooves are likely to be formed on the running surface of the chain guide due to sliding contact with the chain plate. When the groove formed by the sliding contact between the chain plate and the chain running surface of the chain guide becomes deep, the roller of the chain contacts the chain running surface and generates abnormal noise, and there is a risk that the chain guide may be damaged.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a chain transmission device capable of suppressing local wear due to sliding contact with a chain plate in a chain guide. **Means for Solving the Problems**

[0006] In order to solve the above problems, the present invention provides a chain transmission device including a plurality of chain sprockets, an endless chain wound around the plurality of chain sprockets, and a chain guide for guiding the endless chain. The chain guide is provided so as to be reciprocally movable in a direction intersecting the traveling direction of the endless chain, and is characterized by including an actuator for moving the chain guide.

[0007] In the present invention, when the actuator operates, the chain guide moves in a direction intersecting the traveling direction of the endless chain, so that the position of the orbit of the endless chain with respect to the chain guide changes. Therefore, it is possible to suppress local wear of the chain guide due to sliding contact between the chain guide and the endless chain.

[0008] Further, in the above chain transmission device, the actuator may be configured to change the position of the chain guide according to the rotational speed of the chain sprocket. In this case, by changing the position of the chain guide according to the rotational speed of the chain sprocket, if the rotational speed of the chain sprocket changes, the endless chain does not contact the chain guide at a specific position.

[0009] Further, in the above chain transmission device, the actuator may be a hydraulic cylinder, and the hydraulic cylinder includes a cylinder body and a piston rod connected to the chain guide and extending and contracting with respect to the cylinder body. The piston rod may be configured to extend as the rotational speed of the chain sprocket increases and contract as the rotational speed of the chain sprocket decreases. In this case, the position of the chain guide is changed using a hydraulic cylinder. The piston rod of the hydraulic cylinder extends as the rotational speed of the chain sprocket increases and contracts as the rotational speed of the chain sprocket decreases. By utilizing hydraulic pressure, the position of the chain guide can be changed.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a chain transmission device capable of suppressing local wear due to sliding contact with a chain plate in a chain guide.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] (First Embodiment) Hereinafter, the chain sprocket and the chain transmission device according to the first embodiment will be described with reference to the drawings. The chain transmission device of the present embodiment is an example applied to a chain tension adjusting device that adjusts the tension of an endless chain in a diesel engine which is an internal combustion engine. The endless chain is suspended between a crank sprocket provided on a crankshaft and a balance sprocket provided on a balance shaft. The diesel engine which is the internal combustion engine of the present embodiment is mounted on a vehicle.

[0013] The chain transmission device 10 shown in FIG. 1 will be described. In a diesel engine as an internal combustion engine mounted on a vehicle or the like, as shown in FIG. 1, a crankshaft 11 and a balance shaft 12 are provided as rotating shafts. The crankshaft 11 is provided with a crank sprocket 13 as a chain sprocket, and the balance shaft 12 is provided with a balance sprocket 14. An endless chain 15, which is an endless chain, is hung on the crank sprocket 13 and the balance sprocket 14. When the diesel engine is operated, the crankshaft 11 rotates, so the rotational force is transmitted to the balance sprocket 14 via the endless chain 15, and the balance shaft 12 rotates.

[0014] As shown in FIG. 2, the endless chain 15 is a known roller chain including an outer plate 16, an inner plate 17, pins 18, bushes 19, and rollers 20. The outer plate 16 and the inner plate 17 correspond to chain plates. Two pins 18 are joined to the two outer plates 16 by press-fitting. Two bushes 19 are press-fitted and joined to the two inner plates 17. The rollers 20 are loosely fitted around the bushes 19 so that the rollers 20 can rotate freely around the bushes 19.

[0015] A chain guide 21 is installed beside the endless chain 15. The chain guide 21 is a resin member that guides the endless chain 15 when the chain transmission device 10 is driven, and guides the endless chain 15 from the crank sprocket 13 to the balance sprocket 14. The chain guide 21 is a fixed chain guide fixed to the engine body (not shown). The chain guide 21 is the first chain guide.

[0016] As shown in FIG. 3, the chain guide 21 includes a chain guide body portion 22, a chain guide surface 23 formed on the chain guide body portion 22 for guiding the endless chain 15, and a chain guide wall portion 24 rising from an end portion in the width direction of the chain guide surface 23 toward the endless chain 15 side. The chain guide surface 23 is a surface that slidably contacts the outer plate 16 and the inner plate 17 of the endless chain 15. The chain guide wall portion 24 prevents the endless chain 15 from deviating from the chain guide 21. The width of the chain guide surface 23 is set according to the assumed service life of the chain guide 21.

[0017] In the chain transmission device 10 of the present embodiment, in addition to the chain guide 21, a chain guide 30 is provided. The chain guide 30 is the second chain guide. The chain guide 30 is a member that guides the endless chain 15 when the chain transmission device 10 is driven, and guides the endless chain 15 from the balance sprocket 14 to the crank sprocket 13. As shown in FIG. 4, the chain guide 30 includes a chain guide body portion 31, a chain guide surface 32 formed on the chain guide body portion 31 for guiding the endless chain 15, and a chain guide wall portion 33 rising from an end portion in the width direction of the chain guide surface 32 toward the endless chain 15 side. The chain guide surface 32 is a surface that slidably contacts the outer plate 16 and the inner plate 17 of the endless chain 15. The chain guide wall portion 33 prevents the endless chain 15 from deviating from the chain guide 30.

[0018] The chain guide 30 is pivotally supported by the shaft member 34. Therefore, the chain guide 30 is rotatable about the shaft member 34. A tensioner 35 is provided on the back surface of the chain guide 30. The tensioner 35 applies a biasing force to the chain guide 30 so as to always press the chain guide 30 against the endless chain 15. By the chain guide 30 pressing against the endless chain 15 by the tensioner 35, an appropriate tension is generated in the endless chain 15 when the chain transmission device 10 is driven.

[0019] Here, the crank sprocket 13 will be described. As shown in FIG. 1, the crank sprocket 13 of the present embodiment has a disk-shaped sprocket body 41, a boss 42, and a plurality of teeth 43. The crank sprocket 13 is formed by hot forging or cold forging (press forging). The sprocket body 41, the boss 42, and the plurality of teeth 43 are integrally formed. A shaft hole 44 penetrating from the sprocket body 41 to the boss 42 is provided. A crankshaft 11 is inserted into the shaft hole 44. A key groove 45 is formed on the inner wall forming the shaft hole 44. A key 46 is inserted into the key groove 45 so that the crank sprocket 13 does not rotate relative to the crankshaft 11 (see FIG. 1). A plurality of teeth 43 are arranged at equal intervals over the circumferential direction on the outer periphery of the sprocket body 41. The plurality of teeth 43 form a tooth row in the circumferential direction.

[0020] Next, the balance sprocket 14 will be described. As shown in FIG. 1, the balance sprocket 14 has a disk-shaped sprocket body 47 and a plurality of teeth 48. The balance sprocket 14 is formed by hot forging or cold forging (press forging). The sprocket body 47 and the plurality of teeth 48 are integrally formed. The sprocket body 47 is provided with a shaft hole 49, and the balance shaft 12 is inserted into the shaft hole 49 of the balance sprocket 14 and fixed to the balance sprocket 14 so that the balance sprocket 14 does not rotate relative to the balance shaft 12. A plurality of teeth 48 are arranged at equal intervals over the circumferential direction on the outer periphery of the sprocket body 47.

[0021] Incidentally, in the present embodiment, as shown in FIG. 3, a hydraulic cylinder 52 driven by lubricating oil is provided in a cylinder block 51 of a diesel engine (hereinafter simply referred to as "engine") 50. The hydraulic cylinder 52 corresponds to an actuator and has a cylinder body 53 and a piston rod 54 that can move forward and backward with respect to the cylinder body 53. The tip of the piston rod 54 is connected to a chain guide body portion 31 of the chain guide 21. The amount of forward and backward movement of the piston rod 54 is set to be smaller than the width of the chain guide surface 23. The chain guide 21 is provided so as to be reciprocally movable in the width direction intersecting the traveling direction of the endless chain 15. In the present embodiment, guide members 55 for achieving smooth reciprocal movement of the chain guide 21 are provided near the longitudinal ends of the chain guide 21, respectively. A guided portion 56 guided by the guide member 55 is provided on the chain guide body portion 31.

[0022] The hydraulic cylinder 52 communicates with a lubricating oil flow path 57 in the cylinder block 51. The lubricating oil in the lubricating oil flow path 57 is supplied by an oil pump (not shown). When the rotational speed of the engine 50 increases, the oil pressure in the lubricating oil flow path 57 rises, and when the rotational speed of the engine 50 decreases, the oil pressure in the lubricating oil flow path 57 drops. Note that the rotational speed of the chain transmission device 10 is proportional to the rotational speed of the engine 50.

[0023] When the oil pressure in the lubricating oil flow path 57 rises, the piston rod 54 extends with respect to the cylinder body 53 and displaces the chain guide 21 in a direction away from the cylinder block 51. One end of a coil spring 58 is connected to the chain guide 21, and the other end of the coil spring 58 is connected to the tip of the cylinder body 53. The coil spring 58 corresponds to a biasing member that applies a biasing force in a direction to bring the chain guide 21 closer to the cylinder block. Therefore, when the oil pressure in the lubricating oil flow path 57 drops, the piston rod 54 contracts with respect to the cylinder body 53 under the biasing force of the coil spring 58 and is displaced in a direction approaching the cylinder block 51.

[0024] Note that the coil spring 58 is a tension spring that connects the tip of the chain guide 21 and the cylinder body 53, but it is not limited to this. The coil spring may be connected to, for example, the chain guide 21 and the cylinder block 51. Alternatively, a compression coil spring may be provided on the side of the chain guide 21 opposite to the side where the hydraulic cylinder 52 is provided, and the chain guide 21 may be brought closer to the cylinder block 51 by the biasing force of the compression coil spring.

[0025] Next, the operation of the chain transmission device 10 according to the present embodiment will be described. When the crankshaft 11 of the engine 50 rotates, the crank sprocket 13 rotates and feeds out the suspended endless chain 15 toward the balance sprocket 14. The endless chain 15 meshes with the balance sprocket 14 and is fed out toward the crank sprocket 13, thereby rotating the balance sprocket 14. When the balance sprocket 14 rotates, the balance shaft 12 rotates.

[0026] Incidentally, when the rotational speed of the engine 50 increases, the rotational speeds of the crank sprocket 13 and the balance sprocket 14 in the chain transmission device 10 increase. Further, due to the increase in the rotational speed of the engine 50, the oil pressure in the lubricating oil passage 57 rises. That is, the rotational speed of the engine 50 and the oil pressure are in a proportional relationship. When the oil pressure rises, the oil pressure in the cylinder body 53 also rises, and the piston rod 54 of the hydraulic cylinder 52 extends. When the piston rod 54 extends, the chain guide 21 is displaced in a direction away from the cylinder block 51. When the rotational speed of the chain transmission device 10 is neither low nor high, as shown in FIG. 5(a), the chain guide 21 is displaced by the extension of the piston rod 54 so that the endless chain 15 is positioned near the center on the chain guide surface 23. At this time, the endless chain 15 is positioned in the middle in the width direction of the chain guide surface 23.

[0027] When the rotational speed of the engine 50 further increases, the rotational speeds of the crank sprocket 13 and the balance sprocket 14 in the chain transmission device 10 increase. With the increase in the rotational speed of the engine 50, the hydraulic pressure in the lubricating oil passage 57 further rises. For this reason, as shown in FIG. 5(b), due to the increase in the hydraulic pressure, the piston rod 54 of the hydraulic cylinder 52 further extends. Due to the extension of the piston rod 54, the endless chain 15 is positioned on one side (left side) on the chain guide surface 23. That is, when the chain transmission device 10 is rotating at a high speed, the endless chain 15 is positioned on one side (left side) on the chain guide surface 23.

[0028] On the other hand, when the rotational speed of the engine 50 decreases, the rotational speeds of the crank sprocket 13 and the balance sprocket 14 in the chain transmission device 10 decrease. Also, due to the decrease in the rotational speed of the engine 50, the hydraulic pressure in the lubricating oil passage 57 drops. For this reason, as shown in FIG. 5(c), when the hydraulic pressure in the cylinder body 53 also drops due to the decrease in the hydraulic pressure, the piston rod 54 of the hydraulic cylinder 52 contracts with respect to the cylinder body 53 under the biasing force of the coil spring 58. Due to the contraction of the piston rod 54, the chain guide 21 is displaced in a direction approaching the cylinder block 51. For this reason, the endless chain 15 is positioned on the other side (right side) on the guide surface. That is, when the chain transmission device 10 is rotating at a low speed, the endless chain 15 is positioned on the other side (right side) on the chain guide surface 23.

[0029] In this way, according to the operating condition of the engine 50, the chain guide 21 reciprocates in the width direction intersecting the traveling direction of the endless chain 15. As the chain transmission device 10 rotates at a high speed, the endless chain 15 is displaced to one side (left side) of the chain guide surface 23, and as the rotation speed decreases, the endless chain 15 is displaced to the other side (right side) of the chain guide surface 23. Since the position of the endless chain 15 in contact with the chain guide surface 23 changes according to the rotational speed, the outer plate 16 and the inner plate 17 of the endless chain 15 do not continuously slide in contact with the same position of the chain guide surface 23. As a result, local wear of the chain guide surface 23 due to the endless chain 15 is prevented.

[0030] Note that in the high-speed rotation state of the engine 50, although the occurrence frequency is lower compared to the low-speed rotation state, the tension of the endless chain 15 is higher, so the pressing force of the endless chain 15 on the chain guide 21 becomes larger. That is, the load borne by the chain guide 21 due to the tension of the endless chain 15 is large but the duration is short. On the other hand, in the low-speed rotation, the tension of the endless chain 15 is lower compared to the high-speed rotation state, but the low-speed rotation frequency is high. That is, the load borne by the chain guide 21 due to the tension of the endless chain 15 is small but the duration is long. Also, not only is the rotational speed of the engine 50 in a proportional relationship with the hydraulic pressure, but the hydraulic pressure increases in proportion to the load of the engine 50.

[0031] The chain transmission device 10 according to the present embodiment has the following effects. (1) When the actuator operates, the chain guide 21 moves in the width direction intersecting the traveling direction of the endless chain 15, so the position of the orbit of the endless chain 15 with respect to the chain guide 21 changes. Therefore, local wear of the chain guide 21 due to the sliding contact between the chain guide 21 and the endless chain 15 can be suppressed. As a result, it becomes possible to extend the service life of the chain guide 21.

[0032] (2) The actuator changes the position of the chain guide 21 according to the rotational speed of the crank sprocket 13 as a chain sprocket. By changing the position of the chain guide 21 according to the rotational speed of the crank sprocket 13, if there is a change in the rotational speed of the crank sprocket 13, the endless chain 15 will not contact the chain guide 21 at a specific position.

[0033] (3) The actuator is a hydraulic cylinder 52. The hydraulic cylinder 52 has a cylinder body 53 and a piston rod 54 that is connected to the chain guide 21 and expands and contracts with respect to the cylinder body 53. The piston rod 54 extends as the rotational speed of the crank sprocket 13 increases and contracts as the rotational speed of the crank sprocket 13 decreases. Therefore, the position of the chain guide 21 can be changed by using hydraulic pressure.

[0034] (4) By utilizing the hydraulic pressure of the lubricating oil flowing through the lubricating oil flow path 57 in the cylinder block 51 of the engine 50, the hydraulic cylinder 52 as an actuator is operated. Since the lubricating oil in the lubricating oil flow path 57 is supplied by an oil pump, the hydraulic pressure varies according to the rotational speed of the engine 50. Since the engine 50 is mounted on a vehicle, it is possible to move the chain guide 21 in the width direction intersecting the traveling direction of the endless chain 15 according to the driving situation of the vehicle.

[0035] (5) By providing a coil spring 58 as a biasing member, when the rotational speed of the engine 50 decreases and the hydraulic pressure in the lubricating oil flow path 57 decreases, the piston rod 54 can be contracted by the biasing force of the coil spring 58. Therefore, it becomes possible to reciprocate the chain guide 21 in the width direction intersecting the traveling direction of the endless chain 15 according to the operating condition of the engine 50.

[0036] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the invention. For example, it may be modified as follows.

[0037] ○ In the above-described embodiment, the crank sprocket as a chain sprocket in the internal combustion engine is exemplified, and the chain transmission device that transmits the rotational force from the crankshaft to the balance shaft is described. However, the present invention is not limited thereto. The chain sprocket may be, for example, a balance sprocket and is not particularly limited. Further, the chain transmission device may be, for example, a chain transmission device that transmits the rotational force to the camshaft in the internal combustion engine, and any chain transmission device having at least a chain guide may be used. ○ In the above-described embodiment, the first chain guide is displaced in a direction intersecting the traveling direction of the endless chain. However, the present invention is not limited thereto. For example, an actuator may be provided so that the second chain guide is displaced in a direction intersecting the traveling direction of the endless chain. Further, a chain transmission device having a configuration in which the first chain guide and the second chain guide are each displaced in a direction intersecting the traveling direction of the endless chain may be used. ○ In the above-described embodiment, the hydraulic cylinder as the actuator is exemplified and described. However, the present invention is not limited thereto. The actuator may be, for example, an electric motor, and any type of drive source that displaces the chain guide in a direction intersecting the traveling direction of the endless chain may be used. Further, even if the actuator is a hydraulic cylinder, hydraulic oil unrelated to the lubricating oil of the engine cylinder block may be used. ○ In the above-described embodiment, when the first chain guide is reciprocally moved by the actuator, a guide member for smoothly moving the first chain guide is provided. However, the present invention is not limited thereto. For example, the guide member for smoothly moving the first chain guide may not be provided. ○ In the above-described embodiment, the piston rod of the hydraulic cylinder as the actuator is connected to the chain guide. However, the present invention is not limited thereto. For example, the piston rod may be in contact with the chain guide without being connected thereto. ○ In the above embodiment, a coil spring is provided as a biasing means for the piston rod to contract so that the first chain guide can move toward the piston rod side, but the present invention is not limited to this. The biasing means may apply a biasing force that biases the piston rod in the contracting direction with respect to the first chain guide. For example, a leaf spring may be used, or a means whose biasing force is controlled according to the rotation of the engine may be used. ○ In the above embodiment, the chain transmission device provided in the internal combustion engine is illustrated and described, but the present invention is not limited to this. The chain transmission device may be, for example, a chain transmission device driven by an electric motor, and the drive source of the chain drive device is not particularly limited.

Explanation of Signs

[0038] 10 Chain transmission device 11 Crankshaft (rotating shaft) 12 Balance shaft 13 Cranksprocket (chainsprocket) 14 Balance sprocket 15 Endless chain 16 Outer plate 17 Inner plate 21 Chain guide 23, 32 Chain guide surface 30 Chain guide 34 Shaft member 35 Tensioner 41, 47 Sprocket body 50 Engine 51 Cylinder block 52 Hydraulic cylinder (actuator) 53 Cylinder body 54 Piston rod 55 Guide member 56 Guided part 57 Lubricating oil flow path 58 Coil spring

Claims

1. a plurality of chain sprockets, an endless chain wound around the plurality of chain sprockets, and a chain guide for guiding the endless chain, in a chain transmission device, wherein the chain guide is provided so as to be reciprocally movable in a direction intersecting the traveling direction of the endless chain, and an actuator for moving the chain guide is provided. A chain transmission device characterized by this.

2. The chain transmission device according to claim 1, wherein the actuator changes the position of the chain guide according to the rotational speed of the chain sprocket.

3. the actuator is a hydraulic cylinder, the hydraulic cylinder has a cylinder body and a piston rod connected to the chain guide and extending and contracting with respect to the cylinder body, and the piston rod extends as the rotational speed of the chain sprocket increases and contracts as the rotational speed of the chain sprocket decreases. The chain transmission device according to claim 1 or 2, characterized by this.

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