Torque Transmission System

Abstract

To provide a torque transmission system which includes a drive unit having a drive pulley, and generating drive torque for rotating the drive pulley, a driven unit having a driven pulley, and operated by the rotation of the driven pulley, and a transmission belt bridged between the drive pulley and the driven pulley, and transmitting the drive torque to the driven pulley from the drive pulley, and can be placed in a comparatively-small space.SOLUTION: A torque transmission system comprises a tension impartment mechanism including an elastic force generation part interposed between a drive unit and a driven unit, and generating an elastic force according to an inter-device distance being a distance between the drive unit and the driven unit, and imparting tension to a transmission belt by generating an inter-device distance force including the elastic force, and extending the inter-device distance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a torque transmission system, for example, a torque transmission system in which torque is transmitted via a transmission belt wound between a plurality of pulleys. [Background technology]

[0002] In this type of torque transmission system, torque is generally transmitted via a transmission belt from a driving device that generates a driving torque to rotate a driving pulley to a driven device that is actuated by the rotation of a driven pulley. Additionally, tension is applied to the transmission belt to prevent slippage, deflection, and the like of the transmission belt. For example, the accessory drive system described in Patent Document 1 is equipped with an auto-tensioner, as a tensioning mechanism for applying tension to the transmission belt, that presses an idler pulley against the outer peripheral surface of the transmission belt to maintain tension in the transmission belt (in this case, the accessory belt). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-152407 Summary of the Invention [Problem to be solved by the invention]

[0004] The minimum required length of the belt straight portion of a transmission belt varies depending on the pulley alignment error that occurs when the driving device and the driven device are placed in their designated locations. The belt straight portion is a straight section of the transmission belt when viewed from the front (observed from a direction parallel to the rotation axis of the pulleys) and is a section that does not contact rotating members such as the driving pulley and the driven pulley. The pulley alignment error is the difference (offset) between the positions of the two pulleys that contact the transmission belt at both ends of the belt straight portion. If the pulley alignment error becomes large, the possibility of abnormal noise and vibration, uneven wear of the transmission belt, etc. increases. The minimum required length of the belt straight portion is determined, for example, depending on the expected (or allowable) pulley alignment error.

[0005] When maintaining the tension of a transmission belt using an auto-tensioner with an idler pulley, the straight portion of the belt between the idler pulley of the auto-tensioner and the driving pulley, and the straight portion of the belt between the idler pulley and the driven pulley, must both satisfy a minimum required length. Therefore, in many cases, when an auto-tensioner is used, the distance between the driving pulley and the driven pulley is greater than when an auto-tensioner is not used, which in turn increases the likelihood of requiring more space for mounting the driving device and the driven device.

[0006] However, there are cases where the distance between the driving device and the driven device must be relatively small due to environmental constraints in which the driving device and the driven device are installed. The present invention was devised in light of these circumstances, and its object is to provide a torque transmission system that includes a tensioning mechanism that applies tension to a transmission belt and that can be configured so that the distance between the driving device and the driven device can be relatively small. [Means for solving the problem]

[0007] To solve the above problems, a torque transmission system according to a first aspect of the present invention includes a drive device having at least one drive pulley and generating a drive torque to rotate the drive pulley, a driven device having at least one driven pulley and actuated by the rotation of the driven pulley, and a transmission belt stretched between the drive pulley and the driven pulley to transmit the drive torque from the drive pulley to the driven pulley.The torque transmission system further includes an elastic force generating unit interposed between the drive device and the driven device that generates an elastic force corresponding to an inter-device distance between the drive device and the driven device, the elastic force generating unit acting to increase the inter-device distance or a contractile force acting to decrease the inter-device distance, and a tension applying mechanism that applies tension to the transmission belt by generating a device-separating force that increases the inter-device distance, including the elastic force.

[0008] A second aspect of the present invention is a torque transmission system according to the first aspect, wherein the tensioning mechanism holds one of the driving device and the driven device below the other of the driving device and the driven device so that it can move only vertically relative to the other, and generates the device separation force including gravity acting on the one of the driving device and the driven device. The tension applying mechanism may be configured to include a plurality of guide units as follows. That is, the tension applying mechanism holds a lower device, which is one of the driving device and the driven device, below an upper device, which is the other of the driving device and the driven device, so that it can move only in the vertical direction relative to the upper device. The tension applying mechanism includes a plurality of guide units that are vertically expandable and contractible and arranged at a belt-side position between the center of gravity of the lower device and the transmission belt and at a position opposite the transmission belt from the center of gravity in the extension direction of a rotation shaft of one of the driving pulley and the driven pulley associated with the lower device. In this case, the elastic force generating unit may be arranged between the belt-side position and the center of gravity in the extension direction.

[0009] A third aspect of the present invention is a torque transmission system according to the second aspect of the present invention, wherein the driving device is an internal combustion engine, the driven device is a compressor held by the tensioning mechanism so as to be movable only in a vertical direction relative to the internal combustion engine, and the tensioning mechanism has one end fixed to the internal combustion engine and the other end fixed to the compressor, and includes a coil spring that generates the extension force as the elastic force generating part. [Effects of the Invention]

[0010] In the first aspect of the present invention, the device separation force generated by the tensioning mechanism applies tension to the transmission belt wound around the drive pulley and driven pulley. Additionally, the tensioning mechanism includes an elastic force generating unit located between the drive device and the driven device. Therefore, the torque transmission system according to the first aspect of the present invention is capable of applying tension to the transmission belt, and because it does not include an autotensioner, it can be housed in a relatively small housing.

[0011] In the second aspect of the present invention, the device separation force includes gravity acting on the driving device or the driven device. Therefore, compared to when the device separation force does not include gravity, it is more likely that the elastic force generating unit can be made smaller. That is, it is more likely that the driving device and the driven device can be housed in a smaller housing. In addition, because one of the driving device and the driven device can move only vertically relative to the other, even if the transmission belt stretches due to aging and the distance between the devices increases, the pulley alignment error does not increase. Therefore, it is possible to avoid an increased possibility of abnormal noise and vibration, uneven wear of the transmission belt, and the like, occurring when the distance between the devices increases.

[0012] According to the third aspect of the present invention, it is possible to house the torque transmission system including the engine and the compressor in a relatively small housing. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a front view of a torque transmission system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of the torque transmission system. [Figure 3] FIG. 2 is an enlarged cross-sectional view of an elastic force generating section included in the torque transmission system. [Figure 4] FIG. 6 is a front view of a torque transmission system according to a second embodiment of the present invention. [Figure 5] FIG. 2 is a top view of the torque transmission system. DETAILED DESCRIPTION OF THE INVENTION

[0014] First Embodiment A first embodiment of the present invention will be described with reference to Figures 1 to 3. The same reference numerals throughout the description refer to the same elements having the same functions, although duplicated descriptions will not be given. A torque transmission system 1 according to the first embodiment shown in Figures 1 and 2 includes an engine 2, a compressor 3, a transmission belt 4, four guide units 5, and two elastic force generating units 6.

[0015] The torque transmission system 1 is housed in a housing (not shown), and the engine 2 is fixed to the housing. Specifically, as shown in FIGS. 1 and 2, the engine 2 is fixed to a bottom surface 11 inside the housing via four L-shaped metal fittings 11a. Each of the L-shaped metal fittings 11a is fixed (fastened) to the engine 2 using a bolt V1. The state in which the torque transmission system 1 is housed in the housing so that it can be operated is also referred to as the "installed state." The torque transmission system 1 will be described below assuming that it is in the installed state.

[0016] In this embodiment, the torque transmission system 1 constitutes a part of a gas heat pump system. The engine 2 is a well-known gas engine (i.e., an internal combustion engine). The compressor 3 is a well-known compressor that compresses a refrigerant and supplies it to a heat exchanger (not shown) for heating and cooling a building. The transmission belt 4 is a well-known V-belt.

[0017] The engine 2 is a driving device that includes a driving pulley 21 and generates torque (driving torque) to rotate the driving pulley 21. The compressor 3 is a driven device that includes driven pulleys 31 and 32 and is operated by the rotation of the driven pulleys 31 and 32. The transmission belt 4 is stretched between the driving pulley 21 and the driven pulleys 31 and 32 and transmits the driving torque generated by the engine 2 to the compressor 3.

[0018] In the following description, the vertical direction is also referred to as the "up-down direction." The direction perpendicular to the up-down direction and parallel to the rotation axes of the drive pulley 21 and the driven pulleys 31 and 32 is also referred to as the "front-rear direction." The direction in which the drive pulley 21 and the driven pulleys 31 and 32 are arranged relative to the main bodies of the engine 2 and the compressor 3 is also referred to as the "front." The direction perpendicular to the up-down direction and the front-rear direction is also referred to as the "left-right direction."

[0019] As shown in FIG. 1, the driven pulleys 31 and 32 are disposed on the left and right, respectively, and are at the same position in the up-down direction (that is, at the same height).

[0020] The pulley alignment error of the driven pulley 32 relative to the drive pulley 21 is indicated by the distance in the front-to-rear direction between the dashed dotted line L1 and the dashed dotted line L2 shown in Fig. 2. The dashed dotted line L1 is a straight line that is perpendicular to the rotation axis of the drive pulley 21 and passes through the front-to-rear center of the recess (i.e., pulley groove) in the drive pulley 21 into which the transmission belt 4 is inserted. The dashed dotted line L2 is a straight line that is perpendicular to the rotation axis of the driven pulley 32 and passes through the front-to-rear center of the pulley groove of the driven pulley 32.

[0021] 2, the pulley alignment error of the driven pulley 32 relative to the drive pulley 21 is very small. If the dashed-dotted line L2 moves forward or backward relative to the dashed-dotted line L1 (i.e., if the compressor 3 moves forward or backward relative to the engine 2), the magnitude of the pulley alignment error increases.

[0022] In the torque transmission system 1, the pulley alignment error of the driven pulleys 31, 32 relative to the drive pulley 21 is suppressed to a value smaller than the error threshold Lth shown in Fig. 2. In other words, when the engine 2 and / or the compressor 3 are installed, the position of at least one of the engine 2 and the compressor 3 is adjusted so that the pulley alignment error of the driven pulleys 31, 32 relative to the drive pulley 21 becomes smaller than the error threshold Lth.

[0023] 1, the length of the belt straight portion between the drive pulley 21 and the driven pulley 31 and the length of the belt straight portion between the drive pulley 21 and the driven pulley 32 are both length s1. When the pulley alignment error of the driven pulleys 31 and 32 relative to the drive pulley 21 is error threshold Lth, the minimum required length of the belt straight portion between the drive pulley 21 and the driven pulleys 31 and 32 is length threshold Sth.

[0024] In other words, if the length of the belt straight portion is greater than the length threshold value Sth, there is little possibility that abnormal noise or vibration will occur in the transmission belt 4 or that uneven wear will occur in the transmission belt 4 when the engine 2 and the compressor 3 are operating. As can be seen from Fig. 1, the length s1 of the belt straight portion between the drive pulley 21 and the driven pulleys 31 and 32 is less than the length threshold value Sth.

[0025] On the other hand, the pulley alignment error of one of the driven pulleys 31 and 32 relative to the other is adjusted (corrected) to a minute value at the time of manufacturing the compressor 3. Therefore, the length s2 of the belt straight portion between the driven pulley 31 and the driven pulley 32 is longer than the minimum required length of the belt straight portion between the driven pulleys 31 and 32 (a length not shown and shorter than the length threshold Sth).

[0026] As will be described later, the guide unit 5 holds the compressor 3 so that it can move up and down relative to the engine 2. The elastic force generating unit 6 is located between the engine 2 and the compressor 3, and generates an elastic force (for convenience, also referred to as an "extension force") that separates the engine 2 and the compressor 3 from each other. For convenience, the guide unit 5 and the elastic force generating unit 6 are also collectively referred to as a "tensioning mechanism."

[0027] As shown in FIG. 2, two of the guide portions 5 are disposed on the left side of the engine 2 and the compressor 3, and the left guide portions 5 (5a, 5b) are disposed in front and behind. The other two guide portions 5 are disposed on the right side of the engine 2 and the compressor 3, and the right guide portions 5 (guide portion 5 (5c) and the remaining guide portions 5 (not shown)) are disposed in front and behind. As shown in FIG. 1, the front guide portions 5 (5a, 5c) are positioned approximately equal to each other in the front-to-rear direction, and the rear guide portions 5 (guide portion 5 (5b) and the remaining guide portions 5) are positioned approximately equal to each other in the front-to-rear direction.

[0028] 1 and 2, each of the guide units 5 includes a fixed bracket 51 and a slide bracket 55. The upper end of the fixed bracket 51 is fixed to the engine 2 by a pair of bolts V2. The lower end of the slide bracket 55 is fixed to the compressor 3 by a pair of bolts V3.

[0029] A pair of guide pins 52 are disposed on the fixed bracket 51. A pair of elongated holes 56 extending vertically and parallel to each other are formed in the slide bracket 55. The guide pin 52 includes a shaft portion and a tip portion having a diameter larger than that of the shaft portion. One end of the shaft portion of the guide pin 52 opposite the tip portion is fixed to the fixed bracket 51.

[0030] The shaft of the guide pin 52 is inserted into an elongated hole 56 of the slide bracket 55. The length of the elongated hole 56 in the front-to-rear direction is smaller than the diameter of the tip of the guide pin 52. Therefore, the slide bracket 55 is held in place so that it can move up and down relative to the fixed bracket 51 and cannot fall off.

[0031] More specifically, the pair of elongated holes 56 are formed parallel to each other, restricting movement of the slide bracket 55 other than up and down movement relative to the fixed bracket 51. In other words, the slide bracket 55 is restricted from tilting relative to the fixed bracket 51, and thus the longitudinal directions of the slide bracket 55 and the fixed bracket 51 are maintained approximately parallel to each other.

[0032] The two elastic force generating units 6 (6a, 6b) are arranged on the left and right (see FIG. 1), and are located forward of the center of gravity G of the compressor 3 in the front-to-rear direction (see FIG. 2). In this embodiment, the center of gravity G is approximately the same as the geometric center of the compressor 3. As shown enlarged in FIG. 3, each of the elastic force generating units 6 includes an upper base 61, a lower base 62, an inner pipe 63, an outer pipe 64, and a coil spring 65.

[0033] Each of the upper pedestal 61 and the lower pedestal 62 has a disk shape. As shown in Figs. 1 and 2, the upper surface of the upper pedestal 61 is fixed to the lower surface of the engine 2. One end of an inner pipe 63 is fixed to the lower surface of the upper pedestal 61. The lower surface of the lower pedestal 62 is fixed to the upper surface of the compressor 3. One end of an outer pipe 64 is fixed to the upper surface of the lower pedestal 62.

[0034] Each of the inner tube 63 and the outer tube 64 has a cylindrical shape. As shown in Fig. 3, the outer diameter of the inner tube 63 is smaller than the inner diameter of the outer tube 64, and a portion of the inner tube 63 in the longitudinal direction is inserted into the hollow portion of the outer tube 64. The outer diameter of the outer tube 64 is smaller than the inner diameter of the coil spring 65.

[0035] An inner tube 63 and an outer tube 64 are inserted into the hollow portion of the coil spring 65, and the coil spring 65 is pressed in the longitudinal direction by the upper base 61 and the lower base 62. Therefore, the coil spring 65 is shorter than its natural length, and as a result, an extension force is generated.

[0036] 1 and 2, the spring force (i.e., extension force) of the coil spring 65 and gravity acting on the compressor 3 to separate the compressor 3 from the engine 2 in the vertical direction are represented by arrows Av and Ag, respectively. The extension force represented by arrow Av generated by the two elastic force generating units 6 (specifically, the coil springs 65) and the gravity force represented by arrow Ag acting on the compressor 3 are also collectively referred to as "device separation force" for convenience.

[0037] The device separating force biases the compressor 3 so as to increase the distance between the drive pulley 21 and the driven pulleys 31 and 32, and as a result, tension is applied to the transmission belt 4. In other words, a coil spring 65 having an appropriate natural length and spring multiplier is selected in advance so that an appropriate tension is applied to the transmission belt 4.

[0038] The above-mentioned installation state is specifically a state in which the compressor 3 is held by the four guide parts 5 so as to be movable only in the vertical direction relative to the engine 2, and the two elastic force generating parts 6 generate an extension force. In the example shown in Figures 1 and 2, the length in the vertical direction of the elastic force generating parts 6 (6a, 6b) (i.e., the inter-device distance, which is the distance between the bottom surface of the engine 2 and the top surface of the compressor 3) is length d1.

[0039] In this embodiment, the necessary tension cannot be applied to the transmission belt 4 by gravity acting on the compressor 3 alone, so elastic force generating units 6 (6a, 6b) are added to the torque transmission system 1. In other words, the device separation force in this embodiment includes the extension forces generated by the two elastic force generating units 6 and gravity acting on the compressor 3, and applies an appropriate tension to the transmission belt 4.

[0040] When the transmission belt 4 stretches due to aging, the length of the coil spring 65 increases, reducing the difference from its natural length, and the stretching force decreases, albeit slightly. In other words, the device separation force decreases. However, because the device separation force includes gravity acting on the compressor 3, the amount of reduction in the device separation force due to stretching of the transmission belt 4 is smaller than when the device separation force includes only a stretching force.

[0041] As described above, the two elastic force generating units 6 (6a, 6b) are located forward of the center of gravity G of the compressor 3 in the front-rear direction and rearward of the front guide units 5 (5a, 5c) (see FIG. 2). Therefore, compared to when the elastic force generating units 6 are located at the same position as the center of gravity G or rearward of the center of gravity G in the front-rear direction, the force (tilting force) that tilts the compressor 3 in a side view (i.e., from the perspective of FIG. 2) around the joint between the compressor 3 and the guide units 5 (5a, 5c) is reduced.

[0042] More specifically, a device separating force (downward acting force) that moves the compressor 3 downward acts on the compressor 3 behind the guide portions 5 (5a, 5c). On the other hand, a force (upward acting force) that moves the compressor 3 upward acts on the compressor 3 in front of the guide portions 5 (5a, 5c) due to a reaction to the tension applied to the transmission belt 4 by the device separating force.

[0043] The greater the distance in the front-rear direction between the elastic force generating portion 6 and the guide portion 5 (5a, 5c), the greater the contribution of the downward acting force to the tilting force. The greater the distance in the front-rear direction between the driven pulley 31 and the guide portion 5 (5a, 5c), the greater the contribution of the upward acting force to the tilting force.

[0044] In this embodiment, the elastic force generating unit 6 is located forward of the center of gravity G of the compressor 3, and therefore the contribution of the downward acting force to the tilting force is smaller than when the elastic force generating unit 6 is located rearward of the center of gravity G. Therefore, the compressor 3 is held by the guide unit 5 so as to be able to move more smoothly in the vertical direction relative to the engine 2.

[0045] Therefore, for example, if the transmission belt 4 stretches as a result of the torque transmission system 1 operating for a long period of time, the compressor 3 will move away from the engine 2. Specifically, the guide pins 52 disposed on each fixed bracket 51 of the guide unit 5 move relative to the elongated holes 56 formed in the slide bracket 55. In other words, the guide unit 5 (i.e., the combination of the fixed bracket 51 and the slide bracket 55) is a movement direction restricting member that allows the compressor 3 to move only in the vertical direction relative to the engine 2 (i.e., the direction in which the device separating force acts on the compressor 3).

[0046] Therefore, when the transmission belt 4 stretches, the compressor 3 is guided downward by the guide unit 5 due to the device separating force, and the elastic force generating unit 6 is accordingly stretched. In this case, the device separating force (i.e., gravity and the stretching force of the coil spring 65) continues to act on the compressor 3, so that an appropriate tension continues to be applied to the transmission belt 4.

[0047] Here, it is assumed that the compressor 3 is fixed relative to the engine 2, and that tension is applied to the transmission belt 4 by a well-known auto-tensioner that presses an idler pulley against the transmission belt 4 in the section between the drive pulley 21 and the driven pulley 31. That is, the straight belt portion of the transmission belt 4 between the drive pulley 21 and the driven pulley 31 is divided into (a) a first straight belt portion between the drive pulley 21 and the idler pulley, (b) a section where the transmission belt 4 is in contact with the outer peripheral surface of the idler pulley, and (c) a second straight belt portion between the idler pulley and the driven pulley 31.

[0048] In this case, to make the lengths of (a) the first belt straight portion and (c) the second belt straight portion longer than the length threshold value Sth, it is necessary to increase the distance between the drive pulley 21 and the driven pulley 31, or to separate the auto-tensioner from the engine 2 and the compressor 3 and press the idler pulley against the inner circumferential surface of the transmission belt 4. In other words, it is necessary to increase the size of the housing that houses the torque transmission system 1. In other words, by providing a tensioning mechanism (i.e., the guide unit 5 and the elastic force generating unit 6) instead of an auto-tensioner, the torque transmission system 1 can be housed in a relatively small housing.

[0049] Second Embodiment A second embodiment of the present invention will be described with reference to Figures 4 and 5. In the first embodiment, the compressor 3 is held so as to be movable in the vertical direction relative to the engine 2, and the device separating force includes the extension force of the coil spring 65 and gravity acting on the compressor 3. In contrast, in the second embodiment, the compressor 3a is held so as to be movable in the horizontal direction relative to the engine 2a, and the device separating force does not include gravity acting on the compressor 3a. This difference will be described below.

[0050] The torque transmission system 1a according to the second embodiment includes an engine 2a, a compressor 3a, a transmission belt 4a, two guide rails 7, and two elastic force generating units 8. The tension applying mechanism according to the second embodiment includes the guide rails 7 and the elastic force generating units 8.

[0051] The engine 2a includes a drive pulley 21a and generates a drive torque that rotates the drive pulley 21a. The compressor 3a includes a driven pulley 31a and is operated by the rotation of the driven pulley 31a. The transmission belt 4a is stretched between the drive pulley 21a and the driven pulley 31a and transmits the drive torque generated by the engine 2a to the compressor 3a.

[0052] The guide rails 7 (7a, 7b) hold the compressor 3a so that it can move left and right relative to the engine 2a. More specifically, each of the guide rails 7 (7a, 7b) includes a rail portion 71 and a carriage 72. The rail portion 71 is fixed to a housing (not shown) of the torque transmission system 1a. The rail portion 71 is a member that has a substantially rectangular cross section and extends in the longitudinal direction (left and right direction).

[0053] The carriage 72 has a recess that opens downward and covers the upper part of the rail portion 71. In other words, the carriage 72 has a roughly U-shaped cross section. The upper surface of the carriage 72 is fixed to the lower surface of the compressor 3a. The carriage 72 has two carriage rollers 73 (73a, 73b). The carriage rollers 73 (73a, 73b) abut against the upper surface of the rail portion 71 and rotate as the carriage 72 moves in the longitudinal direction of the rail portion 71. Therefore, the carriage 72 (and the compressor 3a) can move smoothly in the left-right direction along the rail portion 71.

[0054] In addition, because the carriage 72 is pressed against the rail portion 71 by gravity acting on the compressor 3a, there is little possibility that the carriage 72 will fall off the rail portion 71. The carriage 72 is restricted from moving in the front-to-rear direction relative to the rail portion 71. In other words, the guide rail 7 is a movement direction restricting member that allows the compressor 3a to move only in the left-to-right direction relative to the engine 2a.

[0055] As shown in Fig. 5, two elastic force generating units 8 (8a, 8b) are arranged in front and behind each other. Each of the elastic force generating units 8 (8a, 8b) has a structure similar to that of the elastic force generating unit 6 described above, and includes a coil spring 81 that generates an extension force instead of the coil spring 65. In the example shown in Figs. 4 and 5, the length of the elastic force generating unit 8 in the left-right direction is d2, which is longer than the length d1 in the up-down direction of the elastic force generating unit 6 of the torque transmission system 1 described above (i.e., d2>d1).

[0056] 4 and 5, the arrow Ah represents the extension force of the elastic force generating unit 8 (specifically, the coil spring 81) acting on the compressor 3 so as to separate the compressor 3a from the engine 2a in the left-right direction. The device separation force in the second embodiment is an extension force generated by the two elastic force generating units 8 (8a, 8b). The device separation force biases the compressor 3a so as to increase the distance between the drive pulley 21a and the driven pulley 31a, and as a result, tension is applied to the transmission belt 4a. Although not shown, the straight belt portion of the transmission belt 4a between the drive pulley 21a and the driven pulley 31a satisfies the minimum required length.

[0057] The extension force generated by the elastic force generating unit 8 of the torque transmission system 1a is greater than the extension force generated by the elastic force generating unit 6 of the torque transmission system 1. This is because the device separation force in the torque transmission system 1 includes the extension force of the coil spring 65 and gravity, whereas the device separation force in the torque transmission system 1a does not include gravity, so the elastic force generating unit 8 needs to generate a greater extension force. In order to generate a greater extension force, a coil spring 81 whose natural length is longer than that of the coil spring 65 is used for the elastic force generating unit 8, and the length d2 of the elastic force generating unit 8 is greater than the length d1 of the elastic force generating unit 6.

[0058] For example, if the torque transmission system 1a operates for a long period of time and the transmission belt 4a stretches, the compressor 3a separates from the engine 2a. Specifically, the carriage 72 moves relative to the rail portion 71. In this case, the device separation force (i.e., the stretching force of the coil spring 81) continues to act on the compressor 3a, so that an appropriate tension continues to be applied to the transmission belt 4a.

[0059] As described above, the torque transmission system 1 according to the first embodiment and the torque transmission system 1a according to the second embodiment can apply appropriate tension to the power transmission belts 4, 4a over a long period of time without using an auto-tensioner. In addition, because the torque transmission systems 1, 1a do not include an auto-tensioner, they can be housed in a relatively small housing. In particular, with the torque transmission system 1, the device separation force includes gravity acting on the compressor 3, so the elastic force generating unit 6 can be made relatively small, and the distance between the engine 2 and the compressor 3 can be made even smaller.

[0060] While the embodiments of the present invention have been described above with reference to the above structures, it will be apparent to those skilled in the art that many alternatives, improvements, and modifications may be made without departing from the scope of the present invention. Accordingly, the present invention encompasses all alternatives, improvements, and modifications that do not depart from the spirit and scope of the appended claims. The present invention is not limited to the specific structures described above, and may be modified, for example, as follows:

[0061] The compressor 3 is held below the engine 2 so as to be movable up and down relative to the engine 2. Alternatively, the engine 2 may be held below the compressor 3 so as to be movable up and down relative to the compressor 3.

[0062] The upper surface of the elastic force generating unit 6 (specifically, the upper surface of the upper pedestal 61) is fixed to the lower surface of the engine 2. Alternatively, the upper surface of the elastic force generating unit 6 may be fixed to a part of the housing of the torque transmission system 1 located below the engine 2 (for example, the machine base on which the engine 2 is placed).

[0063] In the torque transmission systems 1 and 1a, the driving device is the engine 2 and 2a, and the driven device is the compressor 3 and 3a. Alternatively, the driving device may be a driving torque generating source other than an engine, such as an electric motor. The driven device may be a driven device other than a compressor, such as a radiator equipped with a cooling fan connected to a driven pulley so as to be able to transmit torque.

[0064] In the torque transmission system 1, the elastic force generating unit 6 generates an extension force. Alternatively, the elastic force generating unit 6 may be configured to generate a contraction force that acts to reduce the inter-device distance (i.e., the distance between the engine 2 and the compressor 3). For example, if the gravity acting on the compressor 3 is greater than the tension to be applied to the power transmission belt 4, the resultant force of the gravity acting on the compressor 3 and the contraction force of the elastic force generating unit 6 that generates the contraction force (i.e., a force weaker than the gravity acting on the compressor 3) may be applied to the power transmission belt 4 as a device separating force.

[0065] In the torque transmission system 1, the compressor 3 is held by the guide portion 5 so as to be movable in the vertical direction relative to the engine 2. Alternatively, the compressor 3 may be held by a movement direction restricting member including a rail portion and a carriage similar to the guide rail 7 of the torque transmission system 1a so as to be movable in the vertical direction.

[0066] In the torque transmission system 1a, the device separation force does not include gravity acting on the compressor 3a. Instead, the device separation force may include gravity acting on the compressor 3a. Specifically, a heat exchanger (not shown) included in the torque transmission system 1a may be suspended from a wire to the left of the compressor 3a shown in FIG. 4, and the wire may be connected to the left side of the compressor 3a via a bend pulley (not shown) so that gravity acting on the heat exchanger acts in a direction that moves the compressor 3a to the left. [Explanation of symbols]

[0067] 1, 1a... Torque transmission system 2, 2a...Engine 3, 3a...Compressor 4, 4a...Transmission belt 5...Guide section 6...Elastic force generating section 7...Guide rail 8...Elastic force generating section 11...Bottom of the housing 11a…L-shaped bracket 21, 21a...Drive pulley 31, 31a...Driven pulley 32...Driven pulley 51...Fixing bracket 52...Guide pin 55...Slide bracket 56…Long hole 61...Upper pedestal 62...Lower pedestal 63…Inner tube 64...Outer tube 65...Coil spring 71...Rail section 72...Carriage 73...Carriage roller 81...Coil spring V1~V3...Bolts

Claims

1. a drive unit including at least one drive pulley and configured to generate a drive torque to rotate the drive pulley; a driven device having at least one driven pulley and actuated by rotation of the driven pulley; a transmission belt that is stretched between the drive pulley and the driven pulley and transmits the drive torque from the drive pulley to the driven pulley; A torque transmission system comprising: a tension applying mechanism that applies tension to the transmission belt by generating a device separating force that increases the device-to-device distance, including the elastic force, and that includes an elastic force generating unit interposed between the driving device and the driven device, the elastic force generating unit generating an extension force that acts to increase the device-to-device distance or a contraction force that acts to decrease the device-to-device distance, the elastic force corresponding to the device-to-device distance being the distance between the driving device and the driven device; The tensioning mechanism includes: The lower device, which is one of the driving device and the driven device, is held below the upper device, which is the other of the driving device and the driven device, so as to be movable only in the vertical direction relative to the upper device, and includes a plurality of guide portions that are extendable in the vertical direction and are arranged at a belt side position between the center of gravity of the lower device and the transmission belt and at a position on the opposite side of the transmission belt from the center of gravity in the extension direction of a rotation axis of one of the driving pulley and the driven pulley related to the lower device, generating the device separation force including gravity acting on the lower device; Torque transmission system.

2. 2. The torque transmission system of claim 1, The elastic force generating unit is The belt-side position is disposed between the belt side position and the center of gravity in the extension direction. Torque transmission system.

3. 3. A torque transmission system according to claim 2, The drive device is It is an internal combustion engine, The driven device is a compressor held by the tensioning mechanism so as to be movable only in a vertical direction relative to the internal combustion engine, The tensioning mechanism includes: one end of the spring is fixed to the internal combustion engine, and the other end of the spring is fixed to the compressor, and the spring includes a coil spring as the elastic force generating portion for generating the extension force; Torque transmission system.

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