JP5332453B2 - Power transmission device and design method thereof - Google Patents

Description

  The present invention relates to a noise reduction technique for a power transmission device using a chain drive.

  In a chain drive power transmission device, noise is generated due to an impact when the chain meshes with the sprocket. In order to reduce this noise, for example, Patent Document 1 discloses a sprocket provided with a shock absorbing ring. There are also known devices that reduce noise by providing a tensioner that adjusts the tension of the chain and a guide that guides the running of the chain to prevent the chain from sagging.

JP 11-2312 A

  Generally, bush chains and roller chains are constructed by alternately connecting inner links and outer links using pins, and the bushes through which the pins are inserted between both ends of the plates of the inner links. Is provided. The outer peripheral surface of the bush is worn by friction with the hole of the inner link, and the inner peripheral surface is worn by friction with the pin. Due to this wear, the use of the chain tends to increase the pitch between the pins of the inner link, resulting in a longer overall chain length. Therefore, in general, the pitch between the pins of the inner link is set longer than the pitch between the pins of the outer link in consideration of the wear of the bush by design, and with the progress of the wear of the bush due to the use of the chain Thus, these pitches are substantially matched.

  The tensioners and guides described above have a certain effect on noise reduction, but noise may be observed in the initial stage of use, and this noise is correlated with the above-described pitch difference between pins. Thought.

  An object of the present invention is to reduce noise caused by a difference in pitch between pins of a chain.

According to the present invention, a pair of inner plates and an inner link provided with a bush provided between both ends of the inner plate and an outer link provided with a pair of outer plates are connected by a pin through which the bush is inserted. An endless chain that is alternately connected, a plurality of sprockets including at least a first sprocket and a second sprocket, and the first sprocket and the second sprocket of the endless chain, An abutting member that abuts a part of the traveling portion between the first sprocket and the second sprocket , wherein the first sprocket is a drive sprocket having a relatively large diameter. A driven sprocket having a relatively small diameter, and the traveling direction of the traveling portion of the endless chain is the first sprocket. A direction from a sprocket toward the second sprocket, and the contact member is a movable member that constitutes a tensioner that adjusts the tension on the loose side of the endless chain, and the pitch between the pins of the inner link is The outer link is set to be smaller than the pitch between the pins , and the second sprocket side end portion of the end portion of the contact portion between the contact member and the endless chain is 2. The power transmission device according to claim 1, wherein the total number of the inner links and the outer links in an interval from the end portion of the meshing portion of the two sprockets to the endless chain to the end portion on the contact member side is an even number. Is provided.

  In this power transmission device, the total number of the inner links and the outer links in the section is an even number. If an odd number is assumed, a state in which the number of the inner links is larger than the number of the outer links and the opposite state alternately occur in the section, and the length of the chain in the section varies. Where this fluctuation causes noise, the present invention can reduce noise because the length of the chain in the section is constant.

Further, according to this configuration, it is possible to reduce the noise at a portion where the chain is likely to be shaken and vibration is likely to occur.

In the present invention, the total number may be four.

In the present invention, the power transmission device transmits power between the crankshaft of the engine and the balancer shaft of the engine, and the balancer shafts are each provided with a weight portion that is eccentric from the axis. And both sides sandwiching the weight portion include a drive-side balancer shaft and a driven-side balancer shaft that are rotatably supported by a bearing portion provided in the case, and a gear portion that meshes with each other. And the first sprocket is attached to the crankshaft, and the second sprocket is attached to an end of an extension shaft portion extending from the bearing portion of the drive side balancer shaft.

Ri by this configuration, the rotational change in severe engine, for easy mechanism chain noise occurs, the noise can be reduced.

  In the present invention, the endless chain may be a roller chain having a roller through which the bush passes. Moreover, the bush chain which does not have this roller may be sufficient.

Further, according to the present invention, the bush is inserted through the pair of inner plates and the inner link provided with the bush provided between both end portions of the inner plate and the outer link provided with the pair of outer plates. An endless chain alternately connected by pins; a plurality of sprockets including at least a first sprocket and a second sprocket; and the first sprocket and the second sprocket among the endless chains. and and a contact with the contact member to a portion of the running portion between the sprockets, and the crankshaft of the engine, the method of designing a power transmission device for transmitting power between the balancer shaft of the engine, the Each balancer shaft has a weight portion provided eccentrically from the axis, and Both side portions sandwiching the site unit, together with and a rotatably axially supported by the driving balancer shaft and the driven balancer shaft by a bearing portion provided on the case, are connected via a gear unit that meshes with each other, wherein The first sprocket is attached to the crankshaft and is a relatively large-diameter drive-side sprocket, and the second sprocket extends from the bearing portion of the drive-side balancer shaft. Is a driven sprocket having a relatively small diameter, the traveling direction of the traveling portion of the endless chain is a direction from the first sprocket to the second sprocket, and the contact member is , A movable member constituting a tensioner that adjusts the tension on the loose side of the endless chain, and the inner link The pitch between the pins is set to be smaller than the pitch between the pins of the outer link, and the end on the second sprocket side of the end of the contact portion between the contact member and the endless chain The total number of the inner links and the outer links in the section from the end portion to the end portion on the abutting member side of the end portion of the meshing portion of the second sprocket and the endless chain is an even number. A design method for the power transmission device is provided.

  As described above, according to the present invention, it is possible to reduce noise caused by a difference in pitch between pins of a chain.

<Configuration example of power transmission device>
FIG. 1 is a schematic view of an engine 100 to which a power transmission device A according to an embodiment of the present invention is applied. It is the schematic of the engine A to which the bearing structure was applied. Although the engine 100 is a four-cycle in-line four-cylinder gasoline reciprocating engine, the present invention is applicable to other types of engines such as other cylinder row arrangements, the number of cylinders, or a diesel type. The present invention is also applicable to devices other than engines.

  The engine 100 includes a cylinder head 101 and a cylinder block 102. The cylinder head 101 supports an intake-side camshaft 103 and an exhaust-side camshaft 104 so as to be freely rotatable. The driving force of the crankshaft 105 is transmitted by a power transmission mechanism (not shown) and rotates. The intake valve 103a and the exhaust valve 104a are reciprocated, respectively. In the present embodiment, the valve operating mechanism is configured in the DOHC format, and two intake valves 103a and two exhaust valves 104a are provided for each cylinder, and open and close the intake port and the exhaust port facing the combustion chamber.

  A crankshaft 105 extending in the cylinder row direction is rotatably supported on the cylinder block 102. A lower end of a connecting rod 106 is rotatably connected to a crank pin 105 a of the crankshaft 105, and a piston 107 is swingably connected to an upper end of the connecting rod 106. In FIG. 1, the connecting rod 106 and the piston 107 are shown for only one cylinder.

  Below the crankshaft 105, a pair of balancer shafts 110 and 120 are provided in parallel in a direction orthogonal to the cylinder row direction and extending in the cylinder row direction. Each of the balancer shafts 110 and 120 includes weight portions 111 and 121 that are eccentric from the axis thereof, and gear portions 112 and 122 that mesh with each other. The weight parts 111 and 121 are located between the cylinder at the foremost end in the cylinder row direction (that is, the first cylinder) and the cylinder at the end of the end (that is, the fourth cylinder). Located below the cylinder. The gear portions 112 and 122 are, for example, helical gears, and have the same number of teeth, and rotate the balancer shafts 110 and 120 synchronously. The balancer shaft 110 has an extended shaft portion 110a extending from the gear portion 112 to the front side in the cylinder row direction.

  The power transmission device A includes a roller chain 10, sprockets 1 and 2, a chain guide 20, and a chain lever 30. The sprocket 1 is a driving-side sprocket fixed to the end of the crankshaft 105, and the sprocket 2 is a driven-side sprocket fixed to the end of the extension shaft portion 110 a of the balancer shaft 110. The roller chain 10 is an endless chain wound around the sprockets 1 and 2, and transmits the rotational force of the crankshaft 105 to the balancer shaft 110. As a result, the balancer shaft 110 rotates, and the balancer shaft 120 also rotates synchronously with the balancer shaft 110 via the gear portions 112 and 122. The rotation of the balancer shafts 110 and 120 can reduce the vibration of the engine 100.

  FIG. 2 is a view showing a front end surface of the cylinder block 102 and an enlarged view of a main part, and shows a configuration around the power transmission device A. The sprocket 1 and the sprocket 2 are such that the sprocket 1 has a relatively large diameter and the sprocket 2 has a relatively small diameter. In this embodiment, the diameter of the sprocket 2 is about 1 / diameter of the diameter of the sprocket 1. 2 Accordingly, the balancer shafts 110 and 120 are rotated at twice the speed of the crankshaft 105.

  In FIG. 2, the arrow d1 indicates the rotation direction of the sprocket 1 (that is, the rotation direction of the crankshaft 105), and the arrow d2 indicates the traveling direction of the roller chain 10. The sprocket 1 is rotating clockwise. For this reason, when a line passing through the axis of the sprocket 1 and the axis of the sprocket 2 is assumed, the right side of the imaginary line is the loose side of the roller chain 10 and the left side is the tension side of the roller chain. The running direction of the roller chain 10 is the direction from the sprocket 1 toward the sprocket 2 on the right side of the imaginary line, and the direction from the sprocket 2 toward the sprocket 1 on the left side.

  Each of the chain guide 20 and the chain lever 30 has contact surfaces 20a and 30a on which the roller chain 10 is slidably contacted, and is in contact with a part of the traveling portion of the roller chain 10 between the sprocket 1 and the sprocket 2. It is a member. The chain guide 20 is disposed on the tension side of the roller chain 10 and is fixed to the cylinder block 102 so as not to move. The chain lever 30 is disposed on the loose side of the roller chain 10 and is a movable member fixed to the cylinder block 102 via the attachment member 31 so as to be rotatable about the attachment member 31 as a rotation center.

  An actuator 40 is disposed in the vicinity of the chain lever 30. The actuator 40 has a spring therein, and the piston 40a presses the chain lever 30 in the direction of the arrow d3 by the urging force of the spring. That is, the chain lever 30 and the actuator 40 constitute a chain tensioner that adjusts the tension of the roller chain 10 and prevents the slack from occurring on the loose side of the roller chain 10. Oil that circulates in the engine 100 is supplied to the actuator 40, and the vibration of the piston 40a due to the reaction force from the roller chain 10 is attenuated.

  Next, the configuration of the roller chain 10 will be described with reference to FIG. FIG. 3A is an exploded perspective view of the roller chain 10. The roller chain 10 is a general roller chain, and is configured by alternately connecting inner links 11 and outer links 12 with pins 13.

  The inner link 11 includes a pair of inner plates 11a, a bush 11b, and a roller 11c. The bush 11b is provided between both end portions of the inner plate 11a, and is press-fitted into the hole of the inner plate 11a. A bush 11b is inserted through the roller 11c and held between the pair of inner plates 11a. The outer link 12 includes a pair of outer plates 12a. Thus, the inner link 11 and the outer link 12 are connected by inserting the pin 13 into the bush 11b and press-fitting the pin 13 into the hole of the outer plate 12a.

  Here, it is known that the roller chain 10 is worn on the outer peripheral surface and the inner peripheral surface of both ends of the bush 11b due to its use. The outer peripheral surfaces of both ends of the bush 11b are worn by friction with the peripheral wall of the hole of the inner link 11, and the inner peripheral surface of the bush 11b is worn by friction with the pin 13, respectively. As a result, the use of the roller chain 10 increases the pitch between the pins 13 for the inner link 11.

  Therefore, in general, the pitch Pi between the pins 13 of the inner link 11 shown in FIG. 3 is slightly smaller than the pitch Po between the pins 13 of the outer link 12 by design. When the above-described wear progresses due to the use of the roller chain 10, the pitch Pi gradually increases and becomes substantially equal to the pitch Po when the progress of the wear is subsided.

  The present invention pays attention to the fact that noise is likely to be generated during a certain period after the start of use of a new roller chain 10 due to the difference between the pitches Pi and Po.

  The noise of the roller chain 10 is more likely to occur on the loose side than the tension side. In particular, at the portion of the driven sprocket 2 where the roller chain 10 begins to bite, the teeth of the sprocket 2 and the roller chain 10 collide. Noise is likely to occur.

  2 is an enlarged view of a region of the sprocket 2 surrounded by a broken-line circle R in the vicinity of a portion where the roller chain 10 starts to bite. In the present embodiment, of the end portion of the contact portion between the contact surface 30a of the chain lever 30 and the roller chain 10, the end portion of the meshing portion between the sprocket 2 and the roller chain 10 from the end portion on the sprocket 2 side. Among them, the total number of the inner links 11 and the outer links 12 in the section FS to the end of the chain lever 30 is an even number. Thereby, the noise which arises in the sprocket 2 in the part which begins the biting of the roller chain 10 can be reduced. The reason is as follows.

  Since the section FS is a free region that is not restricted by the chain lever 30 and the sprocket 2, the roller chain 10 can vibrate within the section FS. If this vibration can be suppressed, noise can be reduced.

When the total number of the inner links 11 and the outer links 12 in the section FS is an odd number, the number L of any one of these links increases. Therefore, the length L of the roller chain 10 in the section FS is the pitch. The difference between Pi and Po varies with time according to the travel of the roller chain 10. That is, if the total number of the inner links 11 and the outer links 12 in the section FS is N + 1 (N is an even number),
L = N / 2 × (Pi + Po) + Po, or
L = N / 2 × (Pi + Po) + Pi
Thus, such a state where the lengths are different is repeated alternately, and the tension variation of the roller chain 10 occurs. As a result, the roller chain 10 can generate string vibration in the section FS.

On the other hand, when the total number of the inner links 11 and the outer links 12 in the section FS is an even number (N),
L = N / 2 × (Pi + Po)
And does not vary with time and is constant. Therefore, noise can be reduced.

  In the case of the example of FIG. 2, the total number of the inner links 11 and the outer links 12 in the section FS is four, two inner links 11 (# 2, # 4), and two outer links 12 (# 3, # 4). 4). The section FS is specified based on a section in which the roller chain 10 is not substantially restrained by the chain lever 30 and the sprocket 2.

  For this reason, of the end portions of the contact portion between the contact surface 30a of the chain lever 30 and the roller chain 10, the end portion on the sprocket 2 side is in contact with the contact surface 30a in the running direction of the roller chain 10. The first link (in the example shown in FIG. 2, the outer link 12 (# 1) is in contact with the first link.

  Of the end portions of the meshing portion between the sprocket 2 and the roller chain 10, the portion where the roller 11c is first completely meshed with the sprocket 2 (in the example of FIG. 2, the roller 11c of the inner link 11 (# 4) Of these, the roller 11c) on the front side in the running direction of the roller chain 10 is used. In this embodiment, the case where the roller chain 10 is used is illustrated, but a bush chain (without a roller chain roller) can be used instead. In this case, the bush is connected to the sprocket 2. The part should be completely engaged.

Next, in designing the power transmission device A, the total number of the inner links 11 and the outer links 12 in the section FS is, for example,
○ Distance between sprocket 1 and sprocket 2
○ The shape of the contact surface 30a of the chain lever 30,
○ Energizing force of the roller chain 10 by the actuator 40 (projection amount of the piston 40a),
Can be adjusted.

Usually, the length of the roller chain 10 differs between when the power transmission device A is being driven and when it is stopped. In other words, since no tension is generated in the roller chain 10 when it is stopped, the total number of the inner links 11 and the outer links 12 in the section FS may be different from that during the driving. Therefore, the total number of the inner links 11 and the outer links 12 in the section FS is designed based on the case where the power transmission device A is being driven. Due to this design, the confirmation of the total number of the inner links 11 and the outer links 12 when the power transmission device A is being driven is, for example,
○ Confirm by computer simulation,
○ Take a picture of the roller chain 10 in the section FS with a high-speed camera and check it from the image.
Can be mentioned.

  Next, FIG. 3B shows an experimental result of creating an engine 100 having a different total number of inner links 11 and outer links 12 in the section FS (hereinafter referred to as the total number of links) and measuring the noise level thereof. The total number of links was set by changing the inter-axis distance between the sprocket 1 and the sprocket 2 and changing the elongation of the roller chain 10 (the amount of protrusion of the piston 40a), and the roller chain 10 having the same specification was used.

  The inter-shaft distance between the sprocket 1 and the sprocket 2 is the same for three and four links, and the elongation of the roller chain 10 is four and five for the total number of links. It is common. The noise level was obtained by changing the rotational speed of the engine 100 in stages from 1700 to 2400 rpm, and taking the average value of the noise level at each rotational speed.

  From the experimental result of FIG. 3B, when the total number of links is an even number (four), a decrease in the noise level is observed, and between the fact that the total number of links is even or odd and the noise level. It was also experimentally revealed that there is a correlation.

  Next, as described above, setting the total number of the inner links 11 and the outer links 12 in the section FS to an even number is effective in reducing noise, but the total number of the inner links 11 and the outer links 12 in the section FS is smaller. Is preferred. Since the roller chain 10 uses the pin 13 as a bending point, the number of bending points increases as the number of links increases, and the order of the vibration mode increases.

  FIGS. 4A to 4C are explanatory diagrams of the vibration mode, showing the vibration mode of four links in total, with two each of the inner link 11 and the outer link 12. 4A shows the primary vibration mode, FIG. 4B shows the secondary vibration mode, and FIG. 4C shows the tertiary vibration mode. When the total number is 4, it can vibrate in the first to third vibration modes. When the total number is 5, it can vibrate in the first to fourth vibration modes. Thus, the greater the total number of links, the greater the order of the vibration mode. The fact that the order of the vibration mode is large means that the number of resonance rotational speed regions increases accordingly. Therefore, reducing the total number of the inner links 11 and the outer links 12 in the section FS has a noise reduction effect in the sense of reducing the number of resonance rotation speed regions. However, if the total number of links is too small, the drive resistance may increase. For this reason, the total number of the inner links 11 and the outer links 12 in the section FS is preferably 4 or more, and four is optimal.

  Next, in the present embodiment, regarding the section FS between the chain lever 30 and the sprocket 2, the total number of the inner links 11 and the outer links 12 is an even number, but the section between the sprocket 2 and the chain guide 20, the chain The total number of the inner links 11 and the outer links 12 may be an even number for the section between the guide 20 and the sprocket 1 or the section between the sprocket 1 and the chain lever 30. However, since the noise of the roller chain 10 is likely to occur at the loose side of the roller chain 10 and at the beginning of the biting of the driven sprocket 2, the inner link 11 and the outer Making the total number of links 12 an even number is particularly effective for noise reduction.

  In the present embodiment, the number of sprockets around which the roller chain 10 is wound is two, but a configuration of three or more may be used.

  In the present embodiment, the case where the present invention is applied to the driving force transmission between the crankshaft 105 and the balancer shaft 110 is illustrated, but the application example is not limited to this. However, in an engine with a rapid rotation change, the power transmission mechanism of the balancer shaft is likely to generate chain noise. In this embodiment, the noise can be effectively reduced.

<Configuration example of balancer device>
Since the balancer shaft 110 has the eccentric weight portion 111, the balancer shaft 110 vibrates due to its rotation and is likely to be a noise generation source. Here, the structure which reduces the noise resulting from the balancer shaft 110 is demonstrated. This noise reduction configuration caused by the balancer shaft is used in combination with the above-described configuration in which the total number of the inner links 11 and the outer links 12 in the section FS is an even number, so that both chain noise and noise caused by the balancer shaft can be obtained. As a whole, the noise reduction effect can be further enhanced, but only the configuration for reducing the noise caused by the balancer shaft can be adopted for the engine.

  FIG. 5 is a cross-sectional view of engine 100 taken along line XX in FIG. The balancer shafts 110 and 120 are incorporated in the case 210 and unitized as a balancer device 200. In FIG. 5, the balancer shaft 120 is not shown, but is incorporated in the case 210 on the back side of the balancer shaft 110.

  In FIG. 5, the cylinder block 102 includes a lower block 102a positioned below the crankshaft 105 at the lower portion thereof, and the balancer device 200 is fixed to the lower surface of the lower block 102a. The case 210 has an upper case portion 211 and a lower case portion 212, and the balancer shafts 110 and 120 are pivotally supported therebetween.

  The upper case portion 211 and the lower case portion 212 have bearing portions 220 and 221, respectively. The balancer shaft 110 is rotatably supported by the bearing portions 220 and 221 at both sides so as to sandwich the weight portion 111, and the bearing portion 220 supports the portion between the weight portion 111 and the gear portion 112. The bearing portion 220 supports the rear end portion of the balancer shaft 110 in the cylinder row direction. The bearing structure on the balancer shaft 120 side is not shown in FIG. 5, but, similar to the balancer shaft 110, in the portion between the weight portion 121 and the gear portion 122 and the rear end portion in the cylinder row direction. It is pivotally supported.

  With respect to the balancer shaft 110, with respect to the extension shaft portion 110a, a gap 230 is formed between the upper case portion 211 and the lower case portion 212, and is not pivotally supported.

  Here, the weight portions 111 and 121 of the balancer shafts 110 and 120 are positioned below the second cylinder of the engine 100 as described above. In order to reduce the vibration of the engine 100, the cylinders are used in this way. The weight portions 111 and 121 are located below the center in the row direction.

  On the other hand, the drive-side balancer shaft 110 has an extension shaft portion 110a because the driving force needs to be transmitted on the front end face side of the cylinder block 102, and the sprocket 2 is attached to the front end portion in the cylinder row direction. It has been. Since the extension shaft portion 110a has the sprocket 2 as an input portion for driving force at the end thereof, and the bearing portion 220 is separated from the sprocket 2, the extension shaft portion 110a has also conventionally been a case 210. Therefore, a bearing is provided at the space 230 to support the shaft. In the present embodiment, the extension shaft portion 110a is not pivotally supported by the case 210, thereby reducing noise. The reason is as follows.

  Noise caused by the balancer shaft is generated by resonance between the balancer shaft 110 and the case 210. The vibration of the balancer shaft 110 is transmitted from the shaft support location to the case 210. Therefore, it was considered that there is a correlation between the shaft support location and noise.

  Of the three pivotal support portions of the drive-side balancer shaft 110 in the conventional structure, the pivotal support portion of the extension shaft portion 110a is furthest away from the weight portion 111, and therefore the radial direction of the balancer shaft 110 is It is thought that the vibration works most strongly. In addition, since the shaft support portion of the extension shaft portion 110a is closest to the sprocket 2, the bending force of the shaft due to the input of the driving force acts most strongly. That is, it was considered that the vibration energy was the largest at the shaft support portion of the extension shaft portion 110a among the three shaft support portions. And the vibration of the shaft is directly transmitted from the shaft support portion to the case, which leads to an increase in noise due to a resonance phenomenon.

  Therefore, as described above, when a configuration that does not support the extension shaft portion 110a is adopted, noise generated from the balancer device 200 can be reduced.

Thus, the balancer device 200 of the engine 100 is
1. A driving wheel (2) to which rotational driving force is input at one end is provided, and a driving-side balancer shaft (110) having a weight portion (111),
A driven-side balancer shaft (120) having a weight portion (121);
A case (210) provided with a bearing portion that pivotally supports the balancer shafts (110, 120) in a parallel posture;
In the balancer device with
The bearings for the balancer shafts are
The first bearing portion (220) disposed so as to sandwich the weight portion, and the second bearing portion (221), and
The first bearing portion of the drive-side balancer shaft is located closer to the weight portion than the one end portion.

  According to this configuration, it is possible to reduce noise by providing two support portions of the drive-side balancer shaft and disposing the first bearing portion closer to the weight portion. That is, the strong bending force on the input end side of the driving force of the driving-side balancer shaft is not directly transmitted to the case from the vicinity thereof, resonance in the case is suppressed, and noise can be reduced. The drive wheel is typically a sprocket, but may be a pulley in the case of belt transmission, for example.

  Further, according to this configuration, the first and second bearing portions are brought close to the weight portion, so that vibration energy transmitted from the balancer shaft to the case can be further reduced and noise can be reduced. it can.

The balancer device is
2. The balancer shafts each include a drive side gear portion (112) and a driven side gear portion (122) that rotate synchronously,
The both gear portions are arranged on the opposite side of the weight portion of the first or second bearing portion.

  According to this configuration, since the bearings are positioned in the vicinity of the two gear parts, it is possible to reduce noise while ensuring the axial support force around the two gear parts.

FIG. 1 is a schematic view of an engine 100 to which a power transmission device A according to an embodiment of the present invention is applied. FIG. 2 is a view showing a front end face of a cylinder block 102 and an enlarged view of a main part. (A) is a disassembled perspective view of the roller chain 10, (b) is a figure which shows the result of a noise test. (A) thru | or (c) are explanatory drawings of a vibration mode. FIG. 3 is a cross-sectional view of engine 100 along line XX in FIG. 2.

Explanation of symbols

A Power transmission device 1, 2 Sprocket 10 Roller chain 11 Inner link 11a Inner plate 11b Bush 12 Outer link 12a Outer plate 13 Pin

Claims (4)

An endless chain in which a pair of inner plates and an inner link having a bush provided between both ends of the inner plate and an outer link having a pair of outer plates are alternately connected by pins that pass through the bush. When,
A plurality of sprockets including at least first and second sprockets around which the endless chain is wound;
Of the endless chain, an abutting member that abuts a part of a traveling portion between the first sprocket and the second sprocket;
And a power transmission device that transmits power between the crankshaft of the engine and the balancer shaft of the engine ,
Each of the balancer shafts has a weight portion provided eccentrically from the shaft center, and both side portions sandwiching the weight portion are rotatably supported by bearing portions provided in the case. Including a shaft and a follower-side balancer shaft and coupled via a gear portion that meshes with each other;
The first sprocket is attached to the crankshaft and is a relatively large-diameter drive-side sprocket;
The second sprocket is a driven sprocket having a relatively small diameter attached to an end of an extension shaft portion extending from a bearing portion of the drive side balancer shaft ;
A traveling direction of the traveling portion of the endless chain is a direction from the first sprocket toward the second sprocket;
The contact member is a movable member constituting a tensioner that adjusts the tension on the loose side of the endless chain;
The pitch between the pins of the inner link is set smaller than the pitch between the pins of the outer link,
Of the end portions of the contact portion between the contact member and the endless chain, from the end portion on the second sprocket side, from among the end portions of the meshing portion of the second sprocket and the endless chain, the The power transmission device according to claim 1, wherein the total number of the inner links and the outer links in the section to the end on the contact member side is an even number.   The power transmission device according to claim 1, wherein the total number is four. The endless chain is
The power transmission device according to claim 1 or 2, characterized in that said bushing is a roller chain having rollers for inserting. An endless chain in which a pair of inner plates and an inner link having a bush provided between both ends of the inner plate and an outer link having a pair of outer plates are alternately connected by pins that pass through the bush. When,
A plurality of sprockets including at least first and second sprockets around which the endless chain is wound;
Of the endless chain, an abutting member that abuts a part of a traveling portion between the first sprocket and the second sprocket;
And a design method of a power transmission device for transmitting power between the crankshaft of the engine and the balancer shaft of the engine ,
Each of the balancer shafts has a weight portion provided eccentrically from the shaft center, and both side portions sandwiching the weight portion are rotatably supported by bearing portions provided in the case. Including a shaft and a follower-side balancer shaft and coupled via a gear portion that meshes with each other;
The first sprocket is attached to the crankshaft and is a relatively large-diameter drive-side sprocket;
The second sprocket is a driven sprocket having a relatively small diameter attached to an end of an extension shaft portion extending from a bearing portion of the drive side balancer shaft ;
A traveling direction of the traveling portion of the endless chain is a direction from the first sprocket toward the second sprocket;
The contact member is a movable member constituting a tensioner that adjusts the tension on the loose side of the endless chain;
The pitch between the pins of the inner link is set smaller than the pitch between the pins of the outer link,
Of the end portions of the contact portion between the contact member and the endless chain, from the end portion on the second sprocket side, from among the end portions of the meshing portion of the second sprocket and the endless chain, the A method for designing a power transmission device, characterized in that the total number of the inner links and the outer links in the section to the end on the contact member side is an even number.

Images