Belt tensioner device

Abstract

To provide a compact belt tensioner that does not need significant change in layout of a plurality of pulleys.SOLUTION: As an urging pulley 21 linearly moves, the urging pulley 21 urges a belt 12 to adjust the tension of the belt 12. Therefore, unlike the prior arts, it is not necessary to secure a sufficient space for allowing the urging pulley 21 to swing. Further, since an urging part 30 is arranged radially inside the urging pulley 21 relative to the outermost peripheral part of the urging pulley 21 when viewed from an axial direction of the urging pulley 21, the belt tensioner 20 has a compact configuration.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a belt tensioner device. [Background technology]

[0002] Belt tensioner devices that adjust the tension of a belt wound around multiple pulleys have been known. For example, Patent Document 1 discloses a type of belt tensioner device in which a pulley urges a belt by swinging integrally with an arm as the arm swings around a shaft. In this way, the pulley urges the belt, thereby adjusting the tension of the belt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-207163 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which the pulley urges the belt by swinging the pulley integrally with the arm as in Patent Document 1, it is necessary to secure a sufficient space to allow the arm and pulley to swing. Therefore, when attempting to adopt a belt tensioner device as in Patent Document 1, there is a risk that a significant change in the layout of the multiple pulleys will be unavoidable. Therefore, there is a demand for a compact belt tensioner device that does not require a significant change in the layout of the multiple pulleys. [Means for solving the problem]

[0005] A belt tensioner device that solves the above problem is a belt tensioner device that adjusts the tension of a belt wound around a plurality of pulleys, and includes a biasing pulley that biases the belt, and a biasing portion that imparts a biasing force to the biasing pulley so that the biasing pulley biases the belt, wherein the biasing portion causes the biasing pulley to move linearly in a radial direction of the biasing pulley, and when viewed from the axial direction of the biasing pulley, at least a portion of the biasing portion is positioned radially inward of the biasing pulley relative to the outermost peripheral portion of the biasing pulley.

[0006] According to this, when the biasing portion applies a biasing force to the biasing pulley, the biasing pulley moves linearly in the radial direction of the biasing pulley. Then, as the biasing pulley moves linearly, the biasing pulley biases the belt, thereby adjusting the tension of the belt. Therefore, unlike the conventional technology, there is no need to ensure a sufficient space for the biasing pulley to swing. Furthermore, when viewed from the axial direction of the biasing pulley, at least a part of the biasing portion is disposed radially inward of the biasing pulley relative to the outermost periphery of the biasing pulley, so that the belt tensioner device has a compact configuration. As described above, it is possible to provide a compact belt tensioner device that does not require a significant change in the layout of multiple pulleys.

[0007] In the above-described belt tensioner device, when viewed from the axial direction of the biasing pulley, the entire biasing portion is preferably disposed radially inward of the outermost peripheral portion of the biasing pulley.

[0008] This allows the belt tensioner device to be configured more compactly, for example, compared to a case in which, when viewed from the axial direction of the biasing pulley, a portion of the biasing portion protrudes radially outward from the outermost portion of the biasing pulley.

[0009] In the above belt tensioner device, the biasing pulley may be cylindrical, and the biasing portion may be disposed inside the biasing pulley. According to this, since the biasing portion is disposed inside the biasing pulley, the belt tensioner device can be configured more compactly compared to, for example, a case in which the biasing portion protrudes outside the biasing pulley.

[0010] In the above-mentioned belt tensioner device, the biasing portion may include a housing having at least a portion located radially inward of the biasing pulley relative to the outermost peripheral portion of the biasing pulley when viewed from the axial direction of the biasing pulley, a slide member that is slidable in the radial direction of the biasing pulley relative to the housing, a connecting member that connects the slide member and the biasing pulley, and an elastic member that is contained within the housing and biases the slide member in a direction in which the biasing pulley is urged toward the belt.

[0011] According to this, for example, when the tension of the belt is high, the tension acting on the biasing pulley from the belt presses the biasing pulley against the biasing force of the elastic member. As a result, the slide member slides and moves integrally with the biasing pulley through the connecting member relative to the housing in the radial direction of the biasing pulley in the direction opposite to the direction in which the biasing pulley is biased toward the belt. As a result, the elastic member is compressed within the housing. Then, when the tension of the belt decreases, the biasing force of the elastic member overcomes the tension acting on the biasing pulley from the belt, and the elastic member tries to return to its original shape before compression within the housing. As a result, the slide member slides and moves integrally with the biasing pulley through the connecting member relative to the housing in the direction in which the biasing pulley is biased toward the belt, and the biasing pulley biases the belt. As a result, the biasing pulley increases the tension of the belt, so that the decrease in the tension of the belt is suppressed. In such a belt tensioner device, the slide member is slidable relative to the housing, the elastic member is housed within the housing, and at least a portion of the housing is disposed radially inward of the outermost periphery of the biasing pulley when viewed from the axial direction of the biasing pulley, thereby allowing the belt tensioner device to have a compact configuration.

[0012] In the above belt tensioner device, the housing may be disposed inside the biasing pulley. With this, since the housing is disposed inside the biasing pulley, the belt tensioner device can be configured more compactly compared to, for example, a case in which the housing protrudes outside the biasing pulley.

[0013] In the belt tensioner device, the elastic member may be a coil spring. The coil spring is housed in the housing and is suitable as an elastic member for biasing the slide member in a direction in which the biasing pulley is biased toward the belt.

[0014] In the above belt tensioner device, the connecting member may connect the slide member and the biasing pulley at a position closer to the belt than the axis of the biasing pulley.

[0015] This makes it possible to ensure that the stroke of the coil spring is as long as possible, thereby making it easier to ensure the biasing force for biasing the belt by the biasing pulley in the biasing portion.

[0016] In the belt tensioner device, the biasing pulley may have an inner cylinder and an outer cylinder surrounding the inner cylinder, and the biasing portion may have an elastic member disposed between the inner cylinder and the outer cylinder. In this way, since the elastic member is disposed between the inner ring and the outer ring in the biasing portion, the belt tensioner device can be made more compact in configuration.

[0017] In the belt tensioner device, the elastic member may be a leaf spring. A leaf spring is suitable as the elastic member disposed between the inner cylinder and the outer cylinder. Effect of the Invention

[0018] According to the present invention, it is possible to provide a compact belt tensioner device that does not require significant changes to the layout of a plurality of pulleys. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of a belt driving system using a belt tensioner device in a first embodiment. [Diagram 2] FIG. 1 is a front view for explaining a belt tensioner device of a first embodiment. [Diagram 3] 3 is a cross-sectional view taken along line 3-3 in FIG. 2. [Figure 4] FIG. 6 is a front view for explaining a belt tensioner device according to a second embodiment. [Diagram 5] 5 is a cross-sectional view taken along line 5-5 in FIG. 4. [Figure 6] FIG. 11 is a front view for explaining a belt tensioner device according to another embodiment. [Figure 7] 7 is a cross-sectional view taken along line 7-7 in FIG. 6. [Figure 8] FIG. 11 is a front view for explaining a belt tensioner device according to another embodiment. [Figure 9] 9 is a cross-sectional view taken along line 9-9 in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] (First embodiment) A first embodiment of a belt tensioner device will be described below with reference to Figures 1 to 3. The belt tensioner device of the first embodiment is used in a belt drive system. The belt drive system is disposed, for example, in an engine compartment of a vehicle.

[0021] (Overall configuration of the belt drive system 10) 1, the belt drive system 10 includes a plurality of pulleys 11. One of the plurality of pulleys 11 is, for example, a crank pulley provided on a crankshaft of an engine, and the other pulleys 11 are accessory pulleys provided on the rotating shafts of accessories such as a compressor, an alternator, or a water pump.

[0022] The belt drive system 10 includes an endless belt 12. The belt 12 is wound around a plurality of pulleys 11. In the belt drive system 10, the belt 12 is fed in a direction indicated by an arrow R1 in Fig. 1, for example, to transmit power between the pulleys 11 via the belt 12. Specifically, the output from the crankshaft of the engine is transmitted to an accessory such as a compressor, an alternator, or a water pump via a crank pulley, the belt 12, and an accessory pulley.

[0023] (Overall configuration of belt tensioner device 20) 2 and 3, the belt drive system 10 includes a belt tensioner device 20. The belt tensioner device 20 adjusts the tension of the belt 12 wound around a plurality of pulleys 11. The belt tensioner device 20 includes a biasing pulley 21 and a biasing unit 30. The belt tensioner device 20 is attached to the body 15 of the vehicle in the engine compartment.

[0024] (Configuration of the biasing pulley 21) The biasing pulley 21 biases the belt 12. The biasing pulley 21 is cylindrical. The biasing pulley 21 has an inner cylinder 22, an outer cylinder 23, and an end wall 24. The inner cylinder 22 and the outer cylinder 23 are cylindrical. The outer cylinder 23 covers the inner cylinder 22 from the outside of the inner cylinder 22. The outer cylinder 23 surrounds the inner cylinder 22. The axis of the outer cylinder 23 and the axis of the inner cylinder 22 coincide with each other. The axis of the outer cylinder 23 and the axis of the inner cylinder 22 are the axis L1 of the biasing pulley 21. The axial length of the outer cylinder 23 is longer than the axial length of the inner cylinder 22. The end wall 24 is annular. The end wall 24 connects one end of the outer cylinder 23 and one end of the inner cylinder 22. The thickness direction of the end wall 24 coincides with the axial direction of the outer cylinder 23 and the axial direction of the inner cylinder 22. A part of the outer peripheral surface of the outer cylinder 23 contacts the belt 12. The outer peripheral surface of the outer cylinder 23 is the outermost peripheral portion of the biasing pulley 21.

[0025] (Structure of bearing 40) The belt tensioner device 20 includes a bearing 40. The bearing 40 is disposed inside the inner cylinder 22 of the biasing pulley 21. The bearing 40 is an angular ball bearing having an outer ring 41, an inner ring 42, and a plurality of spherical rolling elements 43. The outer ring 41 covers the inner ring 42 on the outside of the inner ring 42. The axis of the outer ring 41 and the axis of the inner ring 42 are aligned with each other. The plurality of rolling elements 43 are disposed between the outer ring 41 and the inner ring 42. The plurality of rolling elements 43 are disposed at intervals in the circumferential direction of the outer ring 41 and the inner ring 42. The outer ring 41 is press-fitted into the inner peripheral surface of the inner cylinder 22. The bearing 40 rotatably supports the biasing pulley 21.

[0026] (Configuration of the biasing portion 30) The urging unit 30 has a housing 31, a slide member 32, a bolt 33 as a connecting member, and a coil spring 34 as an elastic member. The urging unit 30 imparts a urging force to the urging pulley 21 for urging the belt 12 by the urging pulley 21.

[0027] (Configuration of housing 31) The housing 31 has a housing main body 35 and a fixing portion 36. The housing main body 35 is in the shape of a rectangular box. The housing main body 35 is disposed inside the outer tube 23 of the biasing pulley 21. Specifically, the housing main body 35 is disposed inside the outer tube 23 with the longitudinal direction of the housing main body 35 coinciding with the radial direction of the biasing pulley 21.

[0028] The housing main body 35 has an elongated hole 35h. The elongated hole 35h is formed in a wall of the housing main body 35 that is located on the end wall 24 side of the biasing pulley 21. The longitudinal direction of the elongated hole 35h coincides with the longitudinal direction of the housing 31.

[0029] The fixed portion 36 protrudes from the outer surface of the housing main body 35. The fixed portion 36 is, for example, plate-shaped. The fixed portion 36 is an outer surface of the housing main body 35 located in the radial direction of the biasing pulley 21, and protrudes from an outer surface extending in the longitudinal direction of the housing main body 35. A bolt insertion hole 36h is formed in the fixed portion 36. The fixed portion 36 is disposed inside the outer tube 23. Therefore, the housing 31 is disposed inside the outer tube 23. Therefore, the housing 31 is disposed inside the biasing pulley 21.

[0030] The fixing portion 36 is fixed to the boss portion 15a by the fixing bolt 16 passing through the bolt insertion hole 36h being screwed into the boss portion 15a of the body 15. In this manner, the fixing portion 36 is fixed to the boss portion 15a, and the housing 31 is fixed to the body 15. When viewed from the axial direction of the biasing pulley 21, the housing 31 is disposed radially inward of the outermost peripheral portion of the biasing pulley 21.

[0031] (Configuration of slide member 32) The slide member 32 has a slide insertion portion 37 and a flange portion 38. The slide insertion portion 37 is cylindrical and has a female screw hole 37h. The slide insertion portion 37 is inserted into the housing 31 through the long hole 35h of the housing 31. The portion of the slide insertion portion 37 on the opening side of the female screw hole 37h protrudes from the housing 31 through the long hole 35h. The flange portion 38 is a plate-like member that extends outward in an annular shape from the end of the portion of the slide insertion portion 37 protruding from the long hole 35h. The surface of the flange portion 38 on the opposite side to the slide insertion portion 37 contacts the inner ring 42 of the bearing 40. The surface of the flange portion 38 on the slide insertion portion 37 side contacts the periphery of the long hole 35h on the outer surface of the housing main body portion 35. The slide member 32 is slidable relative to the housing main body portion 35 while the slide insertion portion 37 is guided by the long hole 35h. Therefore, the slide member 32 is capable of sliding relative to the housing 31 in the radial direction of the biasing pulley 21 .

[0032] (About Bolt 33) The bolt 33 connects the slide member 32 and the biasing pulley 21. The bolt 33 has a head 33a and a shaft 33b. The shaft 33b is a male threaded portion. The shaft 33b passes through the inside of the inner ring 42 of the bearing 40 and can be screwed into the female threaded hole 37h of the slide insertion portion 37. The head 33a is in contact with a portion of the inner ring 42 of the bearing 40 on the opposite side to the slide member 32. The bolt 33 connects the slide member 32 and the biasing pulley 21 via the bearing 40 by screwing the shaft 33b into the female threaded hole 37h with the head 33a sandwiching the inner ring 42 together with the flange portion 38 of the slide member 32.

[0033] (Regarding the coil spring 34) The coil spring 34 is housed in the housing 31. One end of the coil spring 34 is supported by the slide insertion portion 37. The other end of the coil spring 34 is supported by the inner surface of the housing main body portion 35. The coil spring 34 biases the slide member 32 in a direction in which the biasing pulley 21 is biased toward the belt 12. The coil spring 34 causes the biasing pulley 21 to move linearly in the radial direction of the biasing pulley 21. Therefore, the biasing portion 30 causes the biasing pulley 21 to move linearly in the radial direction of the biasing pulley 21.

[0034] (Regarding the positional relationship between the biasing pulley 21 and the biasing portion 30) The slide member 32 is slidable relative to the housing 31, and the coil spring 34 is housed within the housing 31. The housing 31 does not protrude from the opening of the outer tube 23 on the opposite side to the end wall 24. Therefore, the housing 31 is disposed inside the biasing pulley 21. When viewed from the axial direction of the biasing pulley 21, the entire biasing portion 30 is disposed radially inward of the outermost peripheral portion of the biasing pulley 21.

[0035] (action) Next, the operation of the first embodiment will be described. For example, when the tension of the belt 12 is high, the tension acting on the biasing pulley 21 from the belt 12 presses the biasing pulley 21 against the biasing force of the coil spring 34. As a result, the slide member 32 slides integrally with the biasing pulley 21 relative to the housing 31 via the bolt 33 in the radial direction of the biasing pulley 21 in the direction opposite to the direction in which the biasing pulley 21 is biased toward the belt 12. As a result, the coil spring 34 is compressed within the housing 31.

[0036] Then, when the tension of the belt 12 decreases, the biasing force of the coil spring 34 overcomes the tension acting on the biasing pulley 21 from the belt 12, and the coil spring 34 tries to return to its original shape before being compressed within the housing 31. As a result, the slide member 32 slides integrally with the biasing pulley 21 relative to the housing 31 via the bolt 33 in a direction in which the biasing pulley 21 is biased toward the belt 12, and the biasing pulley 21 biases the belt 12. As a result, the biasing pulley 21 increases the tension of the belt 12, and the decrease in the tension of the belt 12 is suppressed.

[0037] In this manner, when the biasing portion 30 applies a biasing force to the biasing pulley 21, the biasing pulley 21 moves linearly in the radial direction of the biasing pulley 21. Then, in accordance with the linear movement of the biasing pulley 21, the biasing pulley 21 biases the belt 12, and the tension of the belt 12 is adjusted.

[0038] (effect) The first embodiment can provide the following effects. (1-1) As the biasing pulley 21 moves linearly, the biasing pulley 21 biases the belt 12, thereby adjusting the tension of the belt 12. Therefore, there is no need to ensure a sufficient space for the biasing pulley 21 to swing, as in the prior art. Furthermore, when viewed from the axial direction of the biasing pulley 21, the biasing portion 30 is disposed radially inward of the biasing pulley 21 relative to the outermost periphery of the biasing pulley 21, so that the belt tensioner device 20 has a compact configuration. As described above, a compact belt tensioner device 20 can be provided that does not require a significant change in the layout of the multiple pulleys 11.

[0039] (1-2) When viewed from the axial direction of the biasing pulley 21, the entire biasing portion 30 is disposed radially inward of the biasing pulley 21 relative to the outermost peripheral portion of the biasing pulley 21. For example, consider a case in which, when viewed from the axial direction of the biasing pulley 21, a portion of the biasing portion 30 protrudes radially outward of the biasing pulley 21 relative to the outermost peripheral portion of the biasing pulley 21. Compared to this case, the belt tensioner device 20 can be configured more compactly.

[0040] (1-3) The slide member 32 is slidable relative to the housing 31, and the coil spring 34 is housed within the housing 31. When viewed from the axial direction of the biasing pulley 21, the housing 31 is disposed radially inward of the outermost periphery of the biasing pulley 21. This allows the belt tensioner device 20 to have a compact configuration.

[0041] (1-4) The housing 31 is disposed inside the biasing pulley 21. This allows the belt tensioner device 20 to have a more compact configuration than when the housing 31 protrudes outside the biasing pulley 21, for example.

[0042] (1-5) A coil spring is suitable as an elastic member that is housed in the housing 31 and biases the slide member 32 in a direction in which the biasing pulley 21 is biased toward the belt 12. Second embodiment A second embodiment of the belt tensioner device will be described below with reference to Figures 4 and 5. In the embodiment described below, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted or simplified. In the second embodiment, the configurations of the biasing pulley and the biasing portion are different from those in the first embodiment.

[0043] (Configuration of the biasing pulley 21A) As shown in FIG. 4 and FIG. 5, the biasing pulley 21A of the belt tensioner device 20A has an inner cylinder 22A and an outer cylinder 23A. The inner cylinder 22A and the outer cylinder 23A are cylindrical. Therefore, the biasing pulley 21A is cylindrical. The outer cylinder 23A covers the inner cylinder 22A on the outside of the inner cylinder 22A. The outer cylinder 23A surrounds the inner cylinder 22A. The axis of the outer cylinder 23A and the axis of the inner cylinder 22A are aligned with each other. The axial length of the outer cylinder 23A and the axial length of the inner cylinder 22A are the same. A part of the outer peripheral surface of the outer cylinder 23A is in contact with the belt 12. The outer peripheral surface of the outer cylinder 23A is the outermost part of the biasing pulley 21A. The outer ring 41 of the bearing 40 is press-fitted into the inner peripheral surface of the inner cylinder 22A. The bearing 40 rotatably supports the biasing pulley 21A.

[0044] The biasing pulley 21A is attached to the body 15 of the vehicle via a bearing 40. Specifically, the male threaded portion 17a of the fixing bolt 17, which passes through the inside of the inner ring 42 of the bearing 40, is screwed into the boss portion 15a of the body 15, thereby attaching the biasing pulley 21A to the boss portion 15a via the bearing 40. The inner ring 42 of the bearing 40 is sandwiched between the head portion 17b of the fixing bolt 17 and the boss portion 15a. In this way, the bearing 40 is fixed to the boss portion 15a by the fixing bolt 17. As a result, the biasing pulley 21A is attached to the body 15 via the bearing 40.

[0045] (Regarding leaf spring 50) The biasing portion 30A has a plurality of leaf springs 50 as elastic members. Each leaf spring 50 is disposed between the inner tube 22A and the outer tube 23A. Therefore, the biasing portion 30A is disposed inside the biasing pulley 21A. The plurality of leaf springs 50 are disposed at equal intervals in the circumferential direction of the inner tube 22A and the outer tube 23A. One end edge of each leaf spring 50 is connected to the outer circumferential surface of the inner tube 22A. The other end edge of each leaf spring 50 is connected to the inner circumferential surface of the outer tube 23A. Each leaf spring 50 connects the inner tube 22A and the outer tube 23A.

[0046] Each leaf spring 50 applies a biasing force to the biasing pulley 21A for biasing the belt 12 by the biasing pulley 21A. Specifically, each leaf spring 50 is elastically deformable so as to bend in the radial direction of the biasing pulley 21A between the inner cylinder 22A and the outer cylinder 23A. The elastic deformation of each leaf spring 50 allows the outer cylinder 23A to move in a direction toward and away from the inner cylinder 22A.

[0047] (action) Next, the operation of the second embodiment will be described. For example, when the tension of the belt 12 is high, the tension acting on the biasing pulley 21A from the belt 12 presses the outer cylinder 23A of the biasing pulley 21A against the biasing force of each leaf spring 50. This causes each leaf spring 50 to elastically deform. Then, when the tension of the belt 12 decreases, the biasing force of each leaf spring 50 overcomes the tension acting on the biasing pulley 21A from the belt 12, and each leaf spring 50 tries to return to its original shape before elastic deformation. This causes the outer cylinder 23A of the biasing pulley 21A to return to its original position before being pressed by the belt 12, and the outer cylinder 23A of the biasing pulley 21A biases the belt 12. As a result, the biasing pulley 21A increases the tension of the belt 12, and the decrease in the tension of the belt 12 is suppressed.

[0048] In this manner, when the biasing portion 30A applies a biasing force to the biasing pulley 21A, the outer cylinder 23A of the biasing pulley 21A moves linearly in the radial direction. Then, in accordance with the linear movement of the outer cylinder 23A of the biasing pulley 21A, the biasing pulley 21A biases the belt 12, thereby adjusting the tension of the belt 12.

[0049] (effect) In the second embodiment, in addition to the effects (1-1) and (1-2) of the first embodiment, the following effects can be obtained.

[0050] (2-1) The biasing pulley 21A is cylindrical, and the biasing portion 30A is disposed inside the biasing pulley 21A. As a result, since the biasing portion 30A is disposed inside the biasing pulley 21A, the belt tensioner device 20A can be configured more compactly than when, for example, the biasing portion 30A protrudes outside the biasing pulley 21A.

[0051] (2-2) The biasing pulley 21A has an inner cylinder 22A and an outer cylinder 23A surrounding the inner cylinder 22A. The biasing unit 30A has a leaf spring 50 disposed between the inner cylinder 22A and the outer cylinder 23A. As a result, since the leaf spring 50 is disposed between the inner cylinder 22A and the outer cylinder 23A in the biasing unit 30A, the belt tensioner device 20A can be configured more compactly.

[0052] (2-3) The leaf spring 50 is suitable as an elastic member disposed between the inner cylinder 22A and the outer cylinder 23A. (Example of change) The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that no technical contradiction occurs.

[0053] As shown in Figs. 6 and 7, the housing 31 of the biasing portion 30B does not have to be disposed inside the biasing pulley 21B. The belt tensioner device 20 of the embodiment shown in Figs. 6 and 7 includes a cylindrical base 60. The base 60 is press-fitted into the inner peripheral surface of the inner ring 42 of the bearing 40. The biasing pulley 21B is cylindrical. The outer ring 41 of the bearing 40 is press-fitted into the inner peripheral surface of the biasing pulley 21B. The bearing 40 rotatably supports the biasing pulley 21B. The axis L1 of the biasing pulley 21B and the axis of the base 60 coincide with each other. A bolt insertion hole 60h is formed in the base 60. The bolt insertion hole 60h penetrates the base 60 in the axial direction at a position closer to the belt 12 than the axis of the base 60. Therefore, the bolt insertion hole 60h is located closer to the belt 12 than the axis L1 of the biasing pulley 21B. The housing 31 of the biasing part 30B is arranged to be aligned in the axial direction of the biasing pulley 21B with respect to the base part 60. The housing 31 is arranged outside the biasing pulley 21B.

[0054] The shaft portion 33b of the bolt 33 passes through the bolt insertion hole 60h and is screwed into the female screw hole 37h of the slide member 32. The bolt 33 connects the slide member 32 and the biasing pulley 21B via the bearing 40 and the base 60 by screwing the shaft portion 33b into the female screw hole 37h with the head portion 33a sandwiching the base 60 together with the flange portion 38 of the slide member 32. The bolt 33 connects the slide member 32 and the biasing pulley 21B at a position closer to the belt 12 than the axis L1 of the biasing pulley 21B. The coil spring 34 extends in the radial direction of the biasing pulley 21B across the axis L1 of the biasing pulley 21B when the coil spring 34 is in a free length state. This makes it possible to ensure that the stroke of the coil spring 34 is as long as possible. Therefore, in the urging portion 30B, it is possible to easily ensure the urging force for urging the belt 12 by the urging pulley 21B.

[0055] 8 and 9, when viewed from the axial direction of the biasing pulley 21, a part of the biasing portion 30C may protrude radially outward from the outermost peripheral portion of the biasing pulley 21. In short, it is sufficient that at least a part of the biasing portion 30C is disposed radially inward from the outermost peripheral portion of the biasing pulley 21 when viewed from the axial direction of the biasing pulley 21.

[0056] The urging unit 30C has a pair of housings 31. Each housing 31 is disposed at a position where the urging pulley 21 is sandwiched in the axial direction of the urging pulley 21. A part of each housing 31 protrudes outward in the radial direction of the urging pulley 21 from the outermost part of the urging pulley 21 when viewed from the axial direction of the urging pulley 21. Specifically, one end of each housing 31 in the longitudinal direction protrudes outward in the radial direction of the urging pulley 21 from the outermost part of the urging pulley 21 when viewed from the axial direction of the urging pulley 21. In short, it is sufficient that at least a part of the housing 31 is disposed inward in the radial direction of the urging pulley 21 from the outermost part of the urging pulley 21 when viewed from the axial direction of the urging pulley 21.

[0057] The pair of housings 31 are connected to each other by a connection portion 70. The connection portion 70 connects one end of each housing 31 in the longitudinal direction to each other. The connection portion 70 is, for example, plate-shaped. One of the pair of housings 31 has a fixing portion 36. The fixing portion 36 is fixed to the boss portion 15a of the body 15 by screwing the fixing bolt 16 passing through the bolt insertion hole 36h into the boss portion 15a of the body 15.

[0058] The biasing section 30C has a pair of slide members 32 and a pair of coil springs 34. One slide member 32 and one coil spring 34 are housed in each housing 31. The pair of slide members 32 are connected to each other by a support pillar 71. The support pillar 71 is press-fitted into the inner peripheral surface of the inner ring 42 of the bearing 40. The support pillar 71 connects each slide member 32 and the biasing pulley 21 via the bearing 40. Therefore, the support pillar 71 is a connecting member that connects each slide member 32 and the biasing pulley 21.

[0059] Both ends of the support 71 are inserted into each housing 31 through the long hole 35h of each housing 31. And, both ends of the support 71 are connected to each slide member 32. Each coil spring 34 biases each slide member 32 in a direction in which the biasing pulley 21 is biased toward the belt 12. Each coil spring 34 biases each slide member 32 at a position where the biasing pulley 21 is sandwiched in the axial direction of the biasing pulley 21. Therefore, the biasing force from each coil spring 34 acts on both ends of the support 71 through each slide member 32. Therefore, the biasing pulley 21 is easily able to stably move linearly in the radial direction of the biasing pulley 21 together with the bearing 40, the support 71, and each slide member 32.

[0060] In the first embodiment, instead of the coil spring 34, an elastic member such as a solid member made of rubber or silicon may be used. In the second embodiment, instead of the plurality of leaf springs 50, an elastic member such as a solid member made of rubber or silicon may be used.

[0061] In the first embodiment, a part of the housing 31 may protrude from the opening of the outer cylinder 23 on the opposite side to the end wall 24 . In the first embodiment, the connecting member that connects the slide member 32 and the biasing pulley 21 may be, for example, a press-fit pin.

[0062] In each of the above embodiments, the bearing 40 is an angular ball bearing having an outer ring 41, an inner ring 42, and a plurality of spherical rolling elements 43. However, the present invention is not limited to this and may be, for example, a sliding bearing.

[0063] In each of the above-described embodiments, the belt tensioner device 20, 20A is not limited to be used in the belt drive system 10 disposed in the engine compartment of the vehicle, and the use of the belt tensioner device 20, 20A may be changed as appropriate. [Explanation of symbols]

[0064] 11...pulley, 12...belt, 20, 20A...belt tensioner device, 21, 21A, 21B...urging pulley, 22A...inner tube, 23A...outer tube, 30, 30A, 30B, 30C...urging portion, 31...housing, 32...slide member, 33...bolt as connecting member, 34...coil spring as elastic member, 50...leaf spring as elastic member, 71...support as connecting member.

Claims

1. A belt tensioner device for adjusting the tension of a belt wound around a plurality of pulleys, A biasing pulley that biases the belt; a bearing that rotatably supports the biasing pulley; a biasing portion that applies a biasing force to the biasing pulley so that the biasing pulley biases the belt, The biasing portion causes the biasing pulley to move linearly in a radial direction of the biasing pulley, When viewed from an axial direction of the biasing pulley, at least a part of the biasing portion is disposed radially inward of an outermost peripheral portion of the biasing pulley, The biasing portion is a housing, at least a portion of which is disposed radially inward of an outermost peripheral portion of the biasing pulley when viewed from an axial direction of the biasing pulley; a slide member that is slidable relative to the housing in a radial direction of the biasing pulley; a connecting member that connects the slide member and the biasing pulley; an elastic member that is housed in the housing and biases the slide member in a direction in which the biasing pulley is biased toward the belt, the biasing pulley has an inner cylinder having the bearing press-fitted to an inner peripheral surface thereof, an outer cylinder covering the inner cylinder from the outside thereof, and an end wall connecting one end of the inner cylinder and one end of the outer cylinder, the housing has a housing main body and a fixing portion protruding from an outer surface of the housing main body and fixing the housing to a fixed member by a fixing bolt being screwed into the fixing portion; the housing main body is disposed inside the outer cylinder in a state in which a longitudinal direction of a long hole formed in the housing main body coincides with a radial direction of the biasing pulley, the connecting member is a bolt, the bolt connects the shaft portion of the bolt to the slide member with the head portion of the bolt in contact with the bearing, thereby connecting the slide member and the biasing pulley via the bearing; the slide member is inserted into the housing main body through the long hole, The belt tensioner device is characterized in that the elastic member is housed between the slide member and the inner surface of the housing main body within the housing main body, and causes the shank of the bolt connected to the slide member to slide in the radial direction of the biasing pulley while being guided by the long hole.

2. 2. The belt tensioner device according to claim 1, wherein, when viewed from the axial direction of the biasing pulley, the entire biasing portion is disposed radially inward of the outermost peripheral portion of the biasing pulley.

3. The biasing pulley is cylindrical, 3. The belt tensioner device according to claim 2, wherein the biasing portion is disposed inside the biasing pulley.

4. 2. The belt tensioner device according to claim 1, wherein the housing is disposed inside the biasing pulley.

5. 2. The belt tensioner device according to claim 1, wherein the elastic member is a coil spring.

6. 2. The belt tensioner device according to claim 1, wherein the connecting member connects the slide member and the biasing pulley at a position closer to the belt than the axis of the biasing pulley.

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