Chain tensioner

Abstract

Chain tensioner (7), comprising: a lever (9) comprising a sliding contact surface (16) configured to come into sliding contact with a chain (5), and a hub section (15); and a torsion spiral spring (10) comprising a spiral section (18) arranged around the hub section (15), a fixed-side support arm (17) extending from one end of the spiral section (18), and a lever-side support arm (19) extending from the other end of the spiral section (18), wherein when the fixed-side support arm (17) abuts a spring contact section (20), the lever-side support arm (19) abuts a contact surface (21) provided on the lever (9) to exert a preload force of the torsion spiral spring (10) on the lever (9) and tension via the sliding contact surface (16) on the chain (5), wherein the fixed side support arm (17) contains: a restricted section (17a, 17a2), and a press section (17c, 17c2), wherein the lever (9) includes a spring-enclosing section (22, 222) which encloses the locking section (17a, 17a2) and an engagement section (22a, 22a2) which locks the locking section (17a, 17a2) which is enclosed in the spring-enclosing section (22, 222) in a state in which a preload force is applied, and wherein a pressing force is exerted on the pressing section (17c, 17c2) to release the locking of the locking section (17a, 17a2), so that the locking section (17a, 17a2) is removed from the spring mounting section (22, 222) and the locking is released with the engagement section (22a, 22a2).

Description

Technical field

[0001] The present invention relates to a tensioner that exerts tension on a chain, and in particular to a chain tensioner that uses a torsion coil spring to exert a torsional preload force to tension a tensioning lever. State of the art

[0002] In a chain drive system used to power an auxiliary machine, such as an oil pump or compensating device, of an automatic vehicle engine, a chain tensioner is generally used to eliminate chain slack and prevent the chain from vibrating during operation. The tensioner includes a lever that abuts the chain and a torsion coil spring that applies a preload force to tension the chain against the lever. When the chain tensioner is fitted to the chain, it is necessary to install the torsion coil spring in a torsional compression state. This installation is laborious, and the chain tensioner or an engine block can be damaged if installed improperly.

[0003] The prior art discloses a chain tensioner in which a pin locking hole is provided in a lever, a stop pin abuts a support arm of a torsion coil spring on one side, on which the torsion coil spring abuts an engine block in a state in which the support arm is compressed by a predetermined amount, the pin is inserted into the pin locking hole and the chain tensioner is attached to a chain in a state in which a preload force of the torsion coil spring in the lever is removed (see PTL 1). List of literature on patent literature

[0004] JP 6 294 845 B2 Brief description of the invention: Technical problem

[0005] The preload force of the torsion spring is not applied in the chain tensioner when the tensioner is mounted on the chain. Therefore, even if problems can be resolved during installation, it is necessary to release the torsion spring preload by removing the stop pin after the tensioner is attached to the chain. This also means handling the stop pin, which then becomes unnecessary. In the worst-case scenario, the chain tensioner may fail to function because the stop pin is forgotten, or engine problems may occur if the stop pin is dropped into the engine.

[0006] Therefore, it is an object of the invention to provide a chain tensioner that solves the problem described above by absorbing a preload force of a torsion coil spring in a lever without using a stop pin. Problem solving

[0007] The invention provides a chain tensioner comprising: a lever 9, which includes a sliding contact surface 16 configured to come into sliding contact with a chain 5, and a hub section 15; and a torsion coil spring 10 comprising a coil section 18 which fits into the hub section 15, a fixed-side support arm 17 extending from one end of the coil section, and a lever-side support arm 19 extending from the other end of the coil section, wherein, when the fixed-side support arm 17 abuts a contact section 20, the lever-side support arm 19 abuts a contact surface 21 provided on the lever 9 in order to exert a preload force of the torsion coil spring 10 on the lever 9 and to exert tension on the chain 5 via the sliding contact surface 16, the fixed side support arm 17 of the torsion spiral spring 10 contains a locking section 17a 17a2 and a pressing section 17c, 17c2, the lever 9 includes a spring-enclosing section 22, 222 which encloses the locking section, and an engagement section 22a, 22a2 which locks the locking section, which is enclosed in the spring-enclosing section, in a state in which a preload force is exerted, and To release the locking of the locking section 17a 17a2, a pressing force F is exerted on the pressing section 17c, 17c2, so that the locking section 17a, 17a2 is removed from the spring mounting section 22, 222 and the locking is released from the engagement section 22a, 22a2.

[0008] For example, with reference to Fig. 6A to 7E, the chain 5 and the chain tensioner 7 are enclosed in a chain housing 6, and a release projection 27 is provided on a chain cover 25 which covers an open section of the chain housing, and, when the chain housing 6 is covered with the chain cover 25, the release projection 27 presses the press section 17c, 17c2 to release the locking of the locking section 17a, 17a2 from the engagement section 22a, 22a2.

[0009] For example, with reference to Fig. 2B, Fig. 6B, Fig. 6C, Fig. 7C, Fig. 7D and Fig. 7E, the contact section 20 has a tapered surface 20b with a slope to one side opposite a pressing direction of the pressing section 17c, 17c2 and a flat spring contact surface 20a which is continuous with a lower end of the tapered surface.

[0010] For example, with reference to Fig. 1 to 6C, the locking section 17a is formed from a linear section which runs tangentially from the spiral section 18, the spring retaining section 22 is formed from a recessed section which encloses the linear locking section 17a, and the press section 17c is bent away from the locking section and extends beyond the engagement section 22a to one side opposite the spring retaining section 22.

[0011] For example, with reference to Fig. 8A to 8E, the locking section 17a2 is formed from a section obtained by bending a tip end of an extension section 17f, which runs tangentially to the spiral section 18, and extends in an axial direction of the spiral section, The spring mounting section 222 is formed on a raised surface of a coupling section 26, which couples an arc-shaped section 8, which has the sliding contact surface 16, with the hub section 15, and The press section 17c2 is formed from a section obtained by bending a tip end of the locking section 17a2 beyond the engagement section 22a2, and extends in a direction away from the spiral section 18.

[0012] For example, with reference to Fig. 3D, the engagement section 22a is formed from a projecting section which projects to cover a spring preload side of the spring retaining section 22, and The engagement section is inclined such that a projecting amount of a side surface of the locking section 17a decreases in a release direction in a direction from a tip end towards the spiral section.

[0013] The reference symbols in parentheses are for comparison with the drawings and have no effect on the description of the claims. Advantageous effects of the invention

[0014] According to the invention, according to claim 1, the fixed-side support arm of the torsion spiral spring is enclosed in the spring mounting section of the lever, and the torsional preload force of the torsion spiral spring is absorbed by the locking section, which abuts the engagement section, so that when the chain tensioner is not in a state of use during delivery or the like, the chain tensioner can be held in a state in which no tension is exerted by the tensioner on the chain.

[0015] When pressing force is applied to the pressing section, the locking section is removed from the spring retaining section. The locking mechanism of the locking section is released by the engagement section, the torsion spring then abuts the contact section and exerts the torsional preload on the lever, and the chain tensioner applies tension to the chain. Since the locking mechanism of the locking section can be easily released by pressing the pressing section, the torsional spring preload can be released easily and reliably without having to manipulate the stop pin.

[0016] According to the invention, as per claim 2, if the housing cover is provided with the release projection and the chain housing is covered with the housing cover, the release projection can press the press section to automatically release the locking of the locking section due to the engagement section, operational failure of the chain tensioner due to the failure to release the engagement of the engagement section can be reliably prevented, and a pressing operation of the press section due to the release projection is a specified stroke, so that the torsion coil spring can be maintained in a suitable state without being affected by inappropriate deformation and displacement, and the tension can be exerted on the chain by the appropriate chain tensioner.

[0017] According to the invention, as per claim 3, since the contact section contains the tapered surface and the flat spring contact surface, when the press section is pressed and the locking of the torsion coil spring is released, even if the fixed side support arm is deformed or displaced due to the release, the fixed side support arm slides down the tapered surface and is guided to the flat spring contact surface, and the torsion coil spring abuts the contact section at a regular position and exerts the preload force on the lever at a suitable position.

[0018] According to the invention, according to claim 4, since the locking section is a linear section that runs tangentially to the spiral section, and the spring enclosure section is a recessed section that encloses the linear locking section, the locking section is enclosed in the spring enclosure section with a relatively long contact area and can stably maintain a locked state of the torsion spiral spring, and by pressing the pressing section the locking section is bent and deformed and the locking due to the engagement section can be easily released.

[0019] According to the invention, according to claim 5, since the locking section is a section obtained by bending the tip end of the extension section and extends in the axial direction of the spiral section, and the spring-enclosing section is formed on the raised surface in the coupling section, in the fixed-side support arm the locking section is enclosed in the enclosure section in a state in which the extension section is not displaced to a large extent, and the extension section is easily bent by a relatively small pressing force onto the press section, which extends in a direction away from the spiral section, so that the locking section can be reliably removed from the spring-enclosing section and the locking can be easily released due to the engagement section.

[0020] According to the invention, according to claim 6, since the engagement section of the spring enclosure section, which encloses the linear locking section, is formed from a projecting section and the engagement section is inclined such that the projecting amount of the side surface of the projecting section decreases in the release direction in the direction from the tip end to the spiral section when the pressing force is applied to the pressing section to pull the locking section out of the engagement section, the linear locking section can be pulled out of the engagement section at a relatively small extension angle, and the pressing force of the pressing section is sufficiently small, the deformation and displacement of the fixed-side support arm at this time are also sufficiently small, and the preload force can be applied to the lever at a suitable position of the torsion spiral spring.

[0021] Other features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are designated by the same reference numerals. Brief description of the drawings Fig. Figure 1 is a perspective view showing a chain drive device according to an embodiment of the invention. Fig. 2A is a side view of the chain drive device. Fig. 2B is a cross-sectional view of the chain drive device. Fig. Figure 3A is a perspective view of a chain tensioner section of the chain drive device when viewed from a front surface. Fig. Figure 3B is a perspective view of the chain tensioner section of the chain drive device when viewed from a rear surface. Fig. Figure 3C is a front view of the chain tensioner section of the chain drive device when viewed from the rear surface. Fig. 3D is a bottom view of the chain tensioner section of the chain drive device. Fig. Figure 4A is a perspective view of a torsion coil spring of the chain tensioner when viewed from a rear surface. Fig. Figure 4B is a perspective view of the torsion coil spring of the chain tensioner when viewed from a front surface. Fig. 4C is a front view of the chain tensioner's torsion coil spring when viewed from the rear surface. Fig. 4D is a bottom view of the chain tensioner's torsion coil spring. Fig. Figure 5A is a perspective view of the chain tensioner when viewed from the front surface and shows a state in which the torsion coil spring of the chain tensioner is released. Fig. Figure 5B is a perspective view of the chain tensioner when viewed from the rear surface and shows the state in which the torsion coil spring of the chain tensioner is released. Fig. Figure 5C is a front view of the chain tensioner when viewed from the rear surface and shows the state in which the chain tensioner's torsion coil spring is released. Fig. 5D is a bottom view of the chain tensioner's torsion coil spring in the released state. Fig. Figure 6A is a perspective view showing a chain drive device according to a partially modified embodiment. Fig. Figure 6B is a cross-sectional view showing the chain drive device according to the partially modified embodiment and showing a state in which a torsion spiral spring is released. Fig. Figure 6C is a cross-sectional view showing the chain drive device according to the partially modified embodiment and showing a state after the spring has been released. Fig. 7A is a perspective view showing a chain tensioner section of the chain drive device, which is located in Fig. 6A is shown. Fig. 7B is a rear view showing the chain tensioner section of the chain drive device, which is located in Fig. 6A is shown. Fig. 7C is a side view showing the chain tensioner section of the chain drive device, which is located in Fig. 6A is shown. Fig. 7D is a side view showing the chain tensioner section of the chain drive device, which is in Fig. Figure 6A shows the condition after the torsion coil spring has been released. Fig. 7E is a side view showing the chain tensioner section of the chain drive device, which is in Fig. Figure 6A shows the states before and after the spring is released. Fig. Figure 8A is a perspective view of a partially modified chain tensioner when viewed from a front surface. Fig. 8B is a perspective view of the partially modified chain tensioner when viewed from a rear surface. Fig. 8C is a front view of the partially modified chain tensioner. Fig. 8D is a top view of the partially modified chain tensioner. Fig. 8E is a rear view of the partially modified chain tensioner. Description of embodiments

[0022] The following describes embodiments of the invention with reference to the drawings. As in Fig. As shown in Figures 1 to 2B, a chain drive device 1 according to the present embodiment comprises a drive sprocket 2 that engages with an engine crankshaft, a driven sprocket 3 that engages with an auxiliary machine, such as an oil pump or a compensating device, and a chain 5 wound around the two sprockets 2 and 3. The chain 5 is generally a roller chain and may be another type of chain, such as a low-noise chain. The chain drive device 1 is enclosed in a chain housing 6 formed from an engine block. A chain tensioner 7 is arranged in the chain housing 6.

[0023] As in Fig. As shown in Figures 3A to 3D, the chain tensioner 7 includes a lever 9 which is in sliding contact with a slack side of the chain 5, and a torsion coil spring 10 which is compressed between the lever and the chain housing 6 and exerts a predetermined preload force on the lever 9. A condition that is Fig. Figures 1 to 3D show a state in which the torsion coil spring 10 is held in a torsional compression state in the lever 9 and no preload force is exerted on the chain 5, i.e., a state upon delivery to a vehicle manufacturer or the like, before the torsion coil spring is released. Fig. In Figures 1 to 3D, and the same applies to other drawings, a side to which the chain housing of the engine block 6 opens, a side covered by a chain guard (not shown) is referred to as a front surface, and a bottom side of the chain housing 6 is referred to as a rear surface. The lever 9 is made of a synthetic resin and comprises an arc-shaped section 8 with a sliding contact surface 16, a hub section 15, and a coupling section 26. The hub section 15 contains a pivot hole 13, the arc-shaped section 8 has several reinforcing ribs 14 between the arc-shaped sliding contact surface 16 and a linear chord section 16a, a pivot pin 13a is fitted into the pivot hole 13, which penetrates the hub section 15, for attachment to the chain housing 6, the lever 9 is pivotally supported, and the arc-shaped sliding contact surface 16 is in sliding contact with the chain 5.

[0024] As in Fig. As shown in Figures 4A to 4D, the torsion coil spring 10 comprises a coil section 18, with a support arm 17 extending from a front surface of the coil section and a support arm 19 extending from a rear surface of the coil section. When the tensioner is in a state of use, the support arm 17 on the front surface abuts a spring contact section 20 of the chain housing to act as a fixed-side support arm, and the support arm 19 on the rear surface abuts a contact section 21 of the lever 9 to act as a lever-side support arm. The fixed-side support arm 17 is locked to a spring housing section 22 of the lever 9 at the time of delivery, before the spring is released, and interacts with the lever-side support arm 19, which abuts the lever, so that the torsion coil spring 10 is held in a compressed coiled state within the lever 9.

[0025] The fixed-side support arm 17 includes a locking section 17a, which is formed from a linear section extending tangentially from the spiral section 18, a shoulder section 17b that is curved from a tip end of the locking section, and a pressing section 17c that extends from an end of the shoulder section in a direction perpendicular to the shoulder section and is curved at a tip end of the pressing section. The lever-side support arm 19 includes an extension section 19a that extends linearly from the spiral section 18, and a curved section 19b that is curved at the tip end of the extension section.

[0026] As in Fig. 1 and Fig. As shown in Figure 2B, the contact section 20 of the chain housing 6 projects inwards on a side surface of the chain housing of the engine block 6 and includes a flat spring contact surface 20a which abuts the fixed-side support arm 17 of the torsion coil spring 10 during use, and a tapered surface 20b which is positioned such that the support arm 17 abuts the contact surface 20a during a spring release operation.

[0027] This means that the tapered surface 20b has a slope towards the side opposite the pressing direction to the pressing section 17c. The spring contact surface 20a is formed from a flat surface that is continuous with a lower end of the slope and parallel to an axial direction of the spiral section. As shown in Fig. 3B and Fig. As shown in Figure 3C, the contact section 21, against which the lever-side support arm 19 abuts, includes an outer spring stop section 21a formed on the linear section 16a, which is a chord section opposite the sliding contact surface 16 of the arcuate section 8 of the lever 9, and includes a projecting section through which the extension section 19a of the support arm 19 passes, between the outer spring stop section 21a and the coupling section 26, and an abutment section 21b abutting a tip end of the curved section 19b and extending along a rising tip end section of the coupling section 26.

[0028] The spiral section 18 of the torsion spiral spring 10 is wound around an outer circumference of the hub section 15 of the lever 9 and supported by the lever 9. As in Fig. As shown in Figures 3A to 3D, an outer spring stop section 15a is formed at a tip end section of an outer circumferential surface of the hub section 15, and part of it projects radially outward in one direction. The outer stop section prevents the spiral section 18 from disengaging from the hub section 15. The coupling section 26 of the lever 9 couples the linear section 16a, which is the chord section of the arc-shaped section 8, to the hub section 15 and includes a flat plate on its front surface. The hub section 15 is formed on the flat plate, and a rib 26e projects from the flat plate toward a rear surface. An engagement section 22a, projecting from the rear surface, is formed on an edge section of the flat plate, and a groove-shaped recess section between the engagement section 22a and the rib 26e serves as the spring retaining section 22.When a pointed end of the recessed section of the spring retaining section 22 is closed, an edge face of the spring retaining section 22 projects continuously towards the recessed section with a pointed end face to form the engagement section 22a. The locking section 17a of the fixed-side support arm 17 of the torsion coil spring 10 is enclosed in the spring retaining section 22, and the coil spring 10 is held by a preload force of the coil spring 10, so that the locking section 17a is engaged with the engagement section 22a in a torsional compression state. As in . Fig. 3B and Fig. As shown in 3D, the engagement section 22a is inclined such that a side surface of the locking section decreases in a release direction by the amount shown above as it approaches the hub section 15 from the tip end. This means that the engagement section 22a is inclined such that the amount shown on the side surface of the locking section 17a decreases in the release direction from the tip end towards the spiral section 18.

[0029] In the spring-mounted section 22, the tip end of the recess section can pass through the edge section and be eliminated. In this case, the curved shoulder section 17b of the fixed-side support arm 17 is not necessarily required, and the press section 17c can be formed by bending from the tip end of the linear locking section 17a.

[0030] When the chain tensioner 7 is delivered to the vehicle manufacturer, the chain tensioner 7 is not subjected to the preload force of the torsion coil spring 10. As in Fig. As shown in Figures 1 to 3D, the torsion coil spring 10 is fitted into the hub section 15 of the lever 9 with the fixed side support arm 17 as its starting point. Accordingly, the fixed side support arm 17 is positioned on the rear side of the hub section 15 near the coupling section 26 within the torsion coil spring 10. The fixed side support arm 17 is slightly bent and deformed; its locking section 17a is enclosed in the spring retaining housing 22 of the lever 9, and the pressing section 17c projects to one side opposite the coupling section 26 of the lever, so that the torsion coil spring 10 is supported by the lever 9.Therefore, the torsion spiral spring 10 is maintained in a state in which the fixed-side support arm 17 is enclosed in the spring enclosure section 22 by the bending deformation described above and is held in the torsional compression state before the spring is released in the lever 9 by the interaction of the lever-side support arm 19, which abuts the contact section 21 of the lever.

[0031] The chain tensioner 7 is attached to the chain drive device 1 by inserting the pivot pin 13a into the pivot hole 13 and fastening the chain tensioner 7 to the chain housing 6. The tensioner 7 can be easily attached because the preload force of the torsion spring 10 in the lever 9 is relieved.

[0032] To bring the chain drive device 1 into the operating state, it is necessary to release the locking mechanism of the preload force of the torsion spiral spring 10. As described in Fig. As shown in Figures 5A to 5D, a predetermined pressing force F is applied to the pressing section 17c of the torsion coil spring 10, causing the fixed-side support arm 17 to deform against the preload force of the torsion coil spring 10. As a result, the locking section 17a is removed from the spring retaining section 22, and the locking of the fixed-side support arm 17 of the torsion coil spring 10 in the lever 9, as described above, is released. This can be done, as shown in Fig. As shown in Figure 5D, the engagement section 22a of the spring retaining section is inclined according to the deformation of the locking section 17b, and the locking section 17a is pulled out of the spring retaining section 22 at a small angle. Accordingly, the pressing force F is low, the deformation and displacement of the torsion coil spring 10 due to the pressing force are low, and it can be prevented that the position of the torsion coil spring 10 is displaced inappropriately during use.

[0033] When the locking mechanism of the torsion coil spring 10 is released, the fixed-side support arm 17 abuts the contact section 20 of the chain housing 6. As the pressing force F is exerted on the fixed-side support arm 17, the support arm 17 is pushed slightly in the direction of the pressing force. However, since the contact section 20 has the tapered surface 20b in the direction of the pressing force, the support arm 17 abuts the tapered surface and moves towards the flat spring contact surface 20a, which is its normal position. Consequently, the fixed-side support arm 17 abuts the spring contact surface 20a of the contact section, thus the fixed-side support arm 17 abuts the spring contact section 20 in its normal position, so that the torsion coil spring 10 exerts its preload force on the lever 9 in its normal state.

[0034] In this state, the torsion coil spring 10 exerts the preload force on the lever 9 between the torsion coil spring 10 and the contact section 20, and the lever 9 is in a state of use in which the sliding contact surface 16 exerts tension on the chain 5. In the state of use, the chain tensioner 7 is brought into sliding contact with the slack side of the chain 5 by the predetermined preload force, and problems such as vibration and tooth skipping by the chain drive device 1 are prevented, thus maintaining normal rotation.

[0035] The pressing force F exerted on the pressing section 17c is generally applied manually in a state where the housing is removed. In a state where the locking mechanism of the torsion coil spring 10 is released and the chain tensioner 7 is thereby in the operating state, with the spring 10 acting on the lever 9, the chain cover is attached to the chain housing 6.

[0036] Next, a partially modified embodiment will be described with reference to Fig. 6A to 7E described. The present invention is characterized by a method for pressing the pressing section 17c, i.e., a method for releasing the torsion spiral spring 10, wherein the same sections as those of the previous embodiment are designated with the same reference numerals and the description of the configuration is omitted.

[0037] As in Fig. As shown in Figures 6A to 6C, a chain cover 25 is attached to a chain drive device 12 for covering an open section of the chain housing 6. The chain cover 25 has a depth that is essentially equal to that of the chain housing 6 and is attached to the chain housing 6 by approaching the housing 6 from an open side of the chain housing 6 and fastening it with several screws. Fig. Figures 6A to 6C show a state in which the chain cover 25 approaches and is attached to the chain housing 6. The chain cover 25 is provided with a release projection 27 that extends inwards from a base surface of the chain cover 25. The release projection 27 can be a dedicated projection corresponding to a pressing position of the pressing section 17c and pressing the pressing section 17c, or it can also be used as a component with another function, such as a motor controller.

[0038] In the chain drive device 12, as described above, the torsion coil spring 10 is, at the time of delivery, in a state in which the locking section 17a is enclosed in the spring retaining section 22 of the lever 9 and a compression force is absorbed by the lever 9. When the chain drive device 12 is brought into the operating state, the chain housing 6 is covered with the chain cover 25. As described in Fig. As shown in Figures 6B and 7A to 7E, the release projection 27 of the chain cover 25 first comes into contact with the pressing section 17c of the torsion coil spring 10. Then, when the chain cover 25 is further attached to the chain housing 6 and the release projection 27 presses the pressing section 17c, as shown in Figures 6B and 7A to 7E, the following occurs: Fig. As shown in Figure 7D, the locking section 17a of the torsion spiral spring 10 is removed from the housing of the spring mounting section 22, the preload force of the same is released and the fixed side support arm 17 abuts the spring contact section 20 of the chain housing 6 due to the torsional preload force.

[0039] In this case, since the engagement section 22a of the spring mounting section 22 is formed from the inclined surface, see Fig. 5D, a depth of the fixed side support arm 17 at a tip end section of a side of the engagement section 22a furthest from the hub section in the spring retaining section 22 is ensured, and the locking section 17a can be stably locked. At the same time, the extension angle of the fixed side support arm 17 is sufficiently small to release the preload force, and the deformation of the fixed side support arm 17 is also small. As a result, the locking of the fixed side support arm 17 is reliably released by a stroke of a pressing force accompanying the attachment of the chain cover 25, and the fixed side support arm 17 abuts the spring contact section 20 due to the released torsional preload force. In this state, as in Fig. As shown in Figure 7E, the locking section 17A is released from the spring retaining section 22 by a pressing force F from the release section 27, and the contact of the release projection 27 with the pressing section 17c is released. However, the engagement section 17a is bent and deformed, even if the extension angle is small, and, as indicated by an arrow, the fixed-side support arm 17 initially abuts the tapered surface 20b of the spring contact section 20 due to a force from the released torsional preload, slides down the tapered surface due to the inclination of the tapered surface and the spring preload, and is guided to the flat spring contact surface 20a, which is a regular spring receiving surface.

[0040] As a result, the torsion spiral spring 10 is supported by the spring contact section 20 in the regular state with little displacement, such as slippage, during spring release and exerts a normal preload force on the lever 9, and the chain tensioner 7 applies the tension appropriately to the chain 5.

[0041] In the present embodiment, the locking mechanism of the torsion coil spring 10 is automatically released during the installation of the chain cover 25, thus reliably preventing operational failure of the chain tensioner due to forgetting to release the torsion coil spring 10. Furthermore, a pressing operation on the pressing section 17c of the fixed-side support arm can be reliably performed with sufficient force and stroke, the release projection can be released from the pressing section at a suitable rigid position, the torsion coil spring can be maintained in a suitable condition, and appropriate torsional preload can be applied to the chain by the chain tensioner.

[0042] With reference to Fig. Sections 8A to 8E describe a further modified embodiment. The present embodiment differs from the preceding embodiments in the shape of the torsion coil spring and the shape of the locking section of the spring; the other sections are the same, and therefore the same components are designated with the same reference numerals, and their description is omitted.

[0043] The chain tensioner 7 comprises the lever 9 and the torsion spring 10. The lever 9 includes the arc-shaped section 8 with the sliding contact surface 16, the hub section 15, and the coupling section 26. The spiral section 18 of the torsion spring 10 is fitted into the hub section 15, and the lever-side support arm 19 at one end of the torsion spring 10 abuts the contact section 21 of the lever 9. The extension section 19a of the lever-side support arm 19 runs between the intermediate rib 26c of the coupling section 26 and the outer spring stop section 21a. The curved section 19b at the tip end of the lever-side support arm 19 engages with the edge rib 26b of the coupling section 26.

[0044] The coupling section 26 includes a relatively thin flat plate 26a on the front surface, and several ribs 26b, 26c, 26d extend from the flat plate 26a to the rear surface. The edge rib 26b at one tip end also serves as the coupling rib 26e, extends towards the hub section 15, and is coupled at the tip ends of the hub rib 26d, which surrounds the hub section 15 and the intermediate rib 26c. The base end faces of the ribs 26b, 26c, 26d are connected to the linear section 16a of the arcuate section 8. Furthermore, a projecting section 30 extends outwards from the coupling rib 26e to a side opposite the arc-shaped section 8, and a spring retaining section 222, which is formed from a recessed groove section, is formed on a surface of the projecting section 30 that rises away from the hub section 15.

[0045] The hub section 15 is formed on an end section of the flat plate 26a of the coupling section 26 such that it rises towards the rear surface, and the spiral section 10a of the torsion spiral spring 10 is attached to surround an outer circumference of the hub section 15 and is fitted between the hub section 15 and the hub rib 26d. The fixed-side support arm 17 includes, on one side near the flat plate 26a of the torsion spiral spring 10, an extension section 17f, which extends tangentially to the spiral section 18, a locking section 17a2, which is achieved by bending a pointed end of the extension section and extends in the axial direction of the spiral section, and a pressing section 17c2, which is achieved by bending a pointed end of the locking section and extends outwards and parallel to the extension section in a direction away from the spiral section.

[0046] In the as-delivered state, in which the chain tensioner 7 is held in a non-preloaded state, the extension section 17f of the fixed-side support arm 17 of the torsion coil spring 10 runs along a side surface of the projecting section 30, the locking section 17a2 is enclosed in the spring housing section 222, and the pressing section 17c2 extends outwards on the front surface of the lever 9 in a direction away from the spring section. In this state, the torsional preload force of the torsion coil spring 10 is locked by the locking section 17a2, which abuts an engagement section 22a2 on an outer side of the housing section 222, and is released in the lever 9 by the action of the lever-side support arm 19, which abuts the contact section 21.The spring retaining section 222 does not necessarily have to be formed in a recessed groove shape and can be a spring retaining section that is recessed with respect to the engagement section 22a2, in that the engagement section 22a2 is formed in a convex section shape that projects with respect to the spring retaining section.

[0047] When the pressing force F, directed from the front surface to the rear surface, is applied to the pressing section 17c2, the fixed-side support arm 17 of the torsion coil spring 10 bends and deforms the extension section 17f to remove the locking section 17a2 from the spring retaining section 222. As a result, the engagement of the locking section 17a2 with the engagement section 22a2 is released, and the fixed-side support arm 17 of the torsion coil spring 10 abuts the contact section 20 of the chain housing 6 due to the torsional preload force of the torsion coil spring 10. The contact section 20 is formed from the flat spring contact surface 20a and the tapered surface 20b. As described above, the locking section 17a2 is guided to the spring contact surface 20a and the fixed-side support arm 17 is received by the spring contact section 20 in the regular state (see figure). Fig.6A to 7E. Accordingly, the torsion coil spring 10 exerts the preload force on the lever 9 to preload the chain 5 of the chain drive device 1 with tension via the sliding contact surface 16. The pressing force F exerted on the pressing section 17c2 can be exerted by hand, a force when the chain cover is fitted, or any other element. Industrial applicability

[0048] The invention is applicable for use in a chain tensioner. List of reference symbols 1, 12 Chain drive device 5 chain 6 chain cases 7 chain tensioners 8 arc-shaped section 9 levers 10 Torsion spiral spring 15 Hub section 16 sliding contact surfaces 17 Fixed side support arm 17a, 17a2 restricted section 17c, 17c2 Press section 17f Extension section 18 spiral section 19 lever-side support arm 20 Contact section 20a Spring contact surface 20b tapered surface 21 Contact area 22, 222 Spring mounting section 22a, 22a2 Intervention section 25 chain cover 26 Coupling section 27 Release lead F Pressing force

Claims

[1] Chain tensioner (7), comprising: a lever (9) comprising a sliding contact surface (16) configured to come into sliding contact with a chain (5), and a hub section (15); and a torsion spiral spring (10) comprising a spiral section (18) arranged around the hub section (15), a fixed-side support arm (17) extending from one end of the spiral section (18), and a lever-side support arm (19) extending from the other end of the spiral section (18), wherein when the fixed-side support arm (17) abuts a spring contact section (20), the lever-side support arm (19) abuts a contact surface (21) provided on the lever (9) to exert a preload force of the torsion spiral spring (10) on the lever (9) and tension via the sliding contact surface (16) on the chain (5), wherein the fixed side support arm (17) contains: a restricted section (17a, 17a2), and a press section (17c, 17c2), wherein the lever (9) includes a spring-enclosing section (22, 222) which encloses the locking section (17a, 17a2) and an engagement section (22a, 22a2) which locks the locking section (17a, 17a2) which is enclosed in the spring-enclosing section (22, 222) in a state in which a preload force is applied, and wherein a pressing force is exerted on the pressing section (17c, 17c2) to release the locking of the locking section (17a, 17a2), so that the locking section (17a, 17a2) is removed from the spring mounting section (22, 222) and the locking is released with the engagement section (22a, 22a2). [2] Chain tensioner (7) according to claim 1, wherein the chain (5) and the chain tensioner (7) are enclosed in a chain housing (6) and a release projection (27) is provided on a chain cover (25) which covers an open section of the chain housing (6), and, when the chain housing (6) is covered with the chain cover (25), the release projection (27) presses the press section (17c, 17c2) out of the engagement section (22a, 22a2) to release the locking of the locking section (17a, 17a2). [3] Chain tensioner (7) according to claim 1 or 2, wherein the spring contact section (20) has a tapered surface (20b) which has a slope towards a side opposite a pressing direction and a flat spring contact surface (20a) continuous with a lower end of the tapered surface (20b). [4] Chain tensioner (7) according to one of claims 1 to 3, wherein the locking section (17a) is formed from a linear section that runs tangentially to the spiral section (18), the spring mounting section (22) is formed from a recessed section that surrounds the linear locking section (17a), and the press section (17c) is bent out from the locking section (17a) and extends beyond the engagement section (22a) to one side opposite the spring mounting section (22). [5] Chain tensioner (7) according to one of claims 1 to 3, wherein the locking section (17a2) is formed from a section obtained by bending a tip end of an extension section (17f) which runs tangentially to the spiral section (18) and extends in an axial direction of the spiral section (18), the spring mounting section (222) is formed on a raised surface of a coupling section (26) which couples an arc-shaped section (8) having the sliding contact surface (16) to the hub section (15), and the press section (17c2) is formed from a section which is obtained by bending a tip end of the locking section (17a2) beyond the engagement section (22a2) and extends in a direction away from the spiral section (18). [6] Chain tensioner (7) according to claim 4, wherein the engagement section (22a) is formed from a projecting section which projects to cover a spring preload side of the spring retaining section (22), and the engagement section (22a) is inclined such that a projecting amount of a side surface of the locking section (17a) decreases in a release direction when a pressing force is applied to the pressing section to pull the locking section out of the engagement section, in a direction from a tip end to the spiral section (18).

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