Title of Invention

TENSIONER DEVICE

Abstract

To provide a tensioner device in which a plunger included in a lifter presses a tensioner arm to give a predetermined amount of tension to an endless transmission member and which can suppress the generation of hitting sounds between the tensioner arm and the plunger without requiring any cushioning part to be separately provided for the tensioner arm. [Solution] The tensioner device (23) includes the tensioner arm (24) disposed along the cam chain (14) and the lifter (31) having the plunger (33) that presses the tensioner arm (24) toward the cam chain (14). In the tensioner device (23), the pressure receiving part (28) that is included in the tensioner arm (24) and that is pressed by the plunger (33) has the lightening holes (29). [Selected Drawing] FIG. 2

Full Text

[Document Name] Specification [Title of the Invention] TENSIONER DEVICE [Technical Field] [0001] .The present invention relates to a tensioner device which gives a predetermined amount of tension to an endless transmission member, for example, a cam chain used in an engine of a vehicle, for example, a motorcycle. [Background Art] [0002] There have been known tensioner devices which are each provided with a tensioner arm extending along an endless transmission member and a lifter having a plunger to press the tensioner arm toward the endless transmission member and in each of which a pressure receiving part is included in the tensioner arm to receive the pressure from the plunger, the pressure receiving part being provided with a cushioning part to suppress the generation of hitting sounds between the pressure receiving part and the plunger (see the patent document 1, for example). [Patent Document 1] JP-A No. Hll-280857 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0003] The configuration described above of existing tensioner devices includes a cushioning part provided for a tensioner arm. This increases the number of parts of the tensioner device and complicates the tensioner device manufacturing process, so that the cost of manufacturing the tensioner devices can easily increase. Hence, it is an object of the present invention to provide a tensioner device in which a plunger included in a lifter presses a tensioner arm to give a predetermined amount of tension to an endless transmission member and which can suppress the generation of hitting sounds between the tensioner arm and the plunger without requiring any cushioning part to be separately provided for the tensioner arm. [Means for Solving the Problem] [0004] To address the above problem, the invention according to Claim 1 provides a tensioner device (for example, the tensioner device 23 of the following embodiment), comprising a tensioner arm (for example, the tensioner arm • 24 of the following embodiment) disposed along an endless transmission member (for example, the cam chain 14 of the following embodiment) and a lifter (for example, the lifter 31 of the following embodiment) having a plunger (for example, the plunger 33 of the following embodiment) which presses the tensioner arm toward the endless transmission member. In the tensioner device, a pressure receiving part (for example, the pressure receiving part 28 of the following embodiment) which is included in the tensioner arm and which is pressed by the plunger has a lightening portion (for example, a lightening holes 29 or slit holes 129 of the following embodiment). [0005] The invention according to Claim 2 provides the tensioner device: wherein the tensioner arm includes a metallic plate-like core part (for example, the plate-like core part 25 of the following embodiment), a transmission member rubbing part (for example, the chain rubbing layer 26 of the following embodiment) formed on a front side of and integrally with the metallic plate-like core part, and a back coat part (for example, the back coat layer 27 of the following embodiment) formed on a back side of and integrally with the metallic plate-like core part, the transmission member rubbing part and the back coat part each being formed of one of a plate-like rubber member and a plate-like resin member; and wherein the pressure receiving part is formed of a portion of the back coat part, the portion bulging toward the plunger. [0006] The invention according to Claim 3 provides the tensioner device: wherein the tensioner device is of a ratchet type in which retreating of the plunger is restricted every time the lifter advances the plunger by a predetermined length of stroke toward the tensioner arm. [0007] The invention according to Claim 4 provides the tensioner device: wherein the lightening portion is a circular hole formed through the pressure receiving part. [Effect of the Invention] [0008] According to the invention of Claim 1, the stiffness of the pressure receiving part that is included in the tensioner arm and that is pressed by the plunger can be reduced to provide the pressure receiving part with cushioning ability without using any separate cushioning part. This makes it possible to suppress the generation of hitting sound between the tensioner arm and the plunger without increasing the number of parts of the tensioner device and complicating the tensioner device manufacturing process. The "endless transmission member" refers to, for example, a chain or belt, and the "lightening portion" refers to, for example, a hole, recess, slit, or groove. [0009] According to the invention of Claim 2: the lightening portion can be formed easily through the pressure receiving part; the pressure receiving part can bend easily; and the plunger can be kept pressing and abutting on the pressure receiving part. Since the easily bendable pressure receiving part can absorb a play (backlash) in the stroke direction of the plunger, the swaying of the tensioner arm and the generation of the hitting sound, both of which can result from a play of the plunger, can be suppressed. [0010] According to the invention of Claim 3, the bendability of the pressure receiving part allows the plunger to advance a predetermined length of stroke. The plunger can therefore be prevented from generating a play in the stroke direction, so that the swaying of the tensioned arm and the generation of the hitting sound, both of which can result from a play of the plunger, can be suppressed. [0011] According to the invention of Claim 4, the lightening portion can be easily formed even after the back coat layer is formed, and the circular cross-sectional shape of the lightening portion allows the durability of the pressure receiving part to be maintained appropriately. [Best Mode for Carrying Out the Invention] [0012] An embodiment of the present invention will be described below with reference to drawings. For the convenience of description, in each of the drawings referred to in the following, the arrow marked "FR" denotes a forward direction and the arrow marked "UP" denotes an upward direction. [0013] FIG. 1 is a right side view showing an outline of a four-stroke, single-cylinder engine (internal combustion engine hereinafter referred to simply as the "engine") 1 which is mounted, for example, on a motorcycle (saddle-ride type vehicle). The engine 1 includes a crankcase 2 in which a crankshaft 3 is disposed with its rotary axis (crank axis) CI extending laterally (in the vehicle width direction). A cylinder 4 is erected in an obliquely forward upward direction on the crankcase 2. In FIG. 1, reference code C2 denotes an axis extending along the direction in which the cylinder 4 is erected (cylinder axis, i.e. the central axis of the cylinder bore, not shown) . [0014] The cylinder 4 mainly includes a cylinder body 4a provided integrally with the crankcase 2, a cylinder head 4b mounted on the cylinder body 4a, and a head cover 4c fixed on the cylinder head 4b. A piston is fitted in the cylinder bore of the cylinder body 4a. The reciprocating motion of the piston is converted, via a connecting rod, into the rotary motion of the crankshaft 3 (these parts other than the crankshaft 3 are not shown). Intake and exhaust cam shafts la and 8a extending in parallel with the crank axis CI and a valve train mainly including intake and exhaust valves 7 and 8 corresponding to the intake and exhaust cam shafts 7a and 8a are arranged in the cylinder head 4b. [0015] An intake port and an exhaust port (neither is shown) are formed in a rear portion and a front portion of the interior of the cylinder head 4b, respectively. The openings into the combustion chamber of the intake and exhaust ports are opened and closed by the intake and exhaust valves 7 and 8, respectively. A throttle body 13 is connected, to be continuous to the intake port, to a rear portion of the cylinder head 4b. A throttle valve 13a is installed in the throttle body 13 to open and close the intake path. An injector 13b to inject fuel into the intake path is provided in an upper portion of the throttle body 13. ' [0016] A cam chain chamber 15 to accommodate a cam chain 14 which interlocks the crankshaft 3 and the cam shafts 7a and 8a is provided, for example, on a right side of the cylinder 4. The cam chain 14 is an endless chain wound around a cam drive sprocket 16 disposed on the right of the crankshaft 3, an intake cam driven sprocket 17 disposed at a right end portion of the intake cam shaft 7a provided in an upper rear portion of the cylinder 4, and an exhaust cam driven sprocket 18 disposed at a right end portion of the exhaust cam shaft 8a provided in an upper front portion of the cylinder 4. In FIG. 1, arrow Fl denotes the direction in which the cam drive sprocket 16 (crankshaft 3) rotates when the engine is running, and arrows F2 and F3 denote the directions in which the cam driven sprockets 17 and 18 (cam shafts 7a and 8a) rotate, respectively. [0017] A portion toward the front side of the cylinder 4 of the cam chain 14 is referred to as a side pulled by the cam drive sprocket 16 (i.e., tight side), and a portion toward the rear side of the cylinder 4 of the cam chain 14 is referred to as a side fed by the cam drive sprocket 16 (i.e., slack side). A portion toward the top side of the cylinder 4 of the cam chain 14 (the portion spanning over the cam driven sprockets 17 and 18) is regarded as a part of the tight side of the cam chain 14. The cam chain 14 runs over the outer peripheries of the three sprockets and along a plane perpendicular to the lateral direction of the vehicle. [0018] A front chain guide 21 and an upper chain guide 22 are fixed in a front portion and in an upper portion of the cam chain chamber 15, respectively, such that they each probingly contact, from outside the cam chain 14, the outer surface of a tight side portion of the cam chain 14 so as to guide the cam chain 14 along the direction in which the cam chain 14 is to run.. A cam chain tensioner device (hereinafter referred to as the "tensioner device") 23 having a tensioner arm 24 is provided in a rear portion of the cam chain chamber 15 such that the tensioner arm 24 rubbingly contacts, from outside the cam chain 14, the outer surface of a slack side portion of the cam chain 14 so as to appropriately tighten (remove slackening of) the cam chain 14 while, at the same time, guiding the cam chain 14 along the direction in which the cam chain 14 is to run. [0019] Referring also to FIG. 2, the tensioner device 23 includes the tensioner arm 2A extending along the longitudinal direction (running direction) of the cam chain 14 and a lifter 31 having a plunger 33 which presses the tensioner arm 24 toward the cam chain 14. The tensioner arm 24 includes a plate-like core part 25 formed to be laterally in parallel with the width of the cam chain 14, a chain rubbing layer 26, and a back coat layer 27, the chain rubbing layer 26 and the back coat layer 27 being formed, integrally with the plate-like core part 25, on the front and back sides of the plate-like core part 25, respectively. [0020] The plate-like core part 25 is formed of an elastic metal, for example, steel to be gently convex, as seen from a side, into the area bound by the cam chain 14. The tensioner arm 24 extends along the longitudinal direction (running direction) of the cam chain 14 with its upper end portion reaching, heightwise, around an intermediate portion of the cylinder head 4b and its lower end portion reaching, depth wise, around the cam drive sprocket 16. The lower end portion of the tensioner arm 24 includes a swing shaft 24a extending laterally through the lower end portion of the tensioner arm 24. With the swing shaft 24a supported by the crankcase 2, the tensioner arm 24 can swing about the swing shaft 24a. [0021] The chain rubbing layer 26 and the back coat layer 27 are each formed of, for example, fluorinated rubber (or resin) whose hardness is lower than that of the plate-like core part 25. They are each formed to be gently curved along, as seen from a side, the plate-like core part 25. The chain rubbing layer 26 has a guide groove, not shown, formed on its front side to be in rubbing contact with the cam chain 14 and to guide the cam chain 14 along the direction in which the cam chain 14 is to run. The back coat layer 27 has a pressure receiving part 28 formed at its' longitudinally intermediate portion on its back side to receive the pressing force applied by the lifter 31 being described later. [0022] These chain rubbing layer 26, back coat layer 27, and plate-like core part 25 are integrally formed, for example, by insert molding or by bonding after molding. It does not matter whether or not the chain rubbing layer 26 and the back coat layer 27 are formed of an identical material and whether or not the side edges of the plate-like part 25 are covered by the chain rubbing layer 26 or the back coat layer 27. [0023] The lifter 31 includes a holder 32 fixedly inserted, from behind, through a rear wall 15a of the cam chain chamber 15, the plunger 33 reciprocatably held in the holder 32, and a ratchet claw 34 which restricts the motion of the plunger 33 making it movable in one direction only. The holder 32 is disposed behind a longitudinally intermediate portion of the tensioner arm 24. With its front portion inserted, from behind, through the rear wall 15a of the cam chain chamber 15, the holder 32 is fixed, at outside the cam chain chamber 15, to the rear wall 15a using a fixing flange 32a and a fixing bolt 32b. [0024] The holder 32 includes a holding hole 32c extending, along an axis C3, through the holder 32 from- behind, the axis C3 approximately perpendicularly crossing the cylinder axis C2. The plunger 33 is reciprocatably held in a front portion of the holding hole 32c. A plug bolt 35 is screwed to a rear portion of the holding hole 32c. A compression coil spring 3 6 is fitted in an inner front portion of the plug bolt 35 such that a front end portion of the compression coil spring 36 pushes a rear end portion of the plunger 33 to bias the plunger 33 forward (toward the tensioner arm 24) along the axis (plunger axis) C3. [0025] A rack section 33a is formed on an upper surface portion of the plunger 33, the rack section 33a including teeth arranged along the plunger axis C3. The ratchet claw 34 that can engage the rack section 33a is rotatably supported in a front portion of the holder 32. The ratchet claw 34 is supported in the front portion of the holder 32 to be rotatable about a rotary shaft 34a extending perpendicularly to the plunger axis C3. It is biased by the spring force of a compression coil spring 37 held in a front portion of the holder 32 such that its claw end portion 34b is pushed against the rack section 33a (pushed for engagement). [0026] The claw end portion 34b is positioned forward of the rotary shaft 34a. When the plunger 33 advances toward the tensioner arm 24, the claw end portion 34b is pushed upward over the teeth of the rack section 33a opposing the spring force of the coil spring 37 not to restrict the movement of the plunger 33. When the plunger 33 retreats from the tensioner arm 24, the claw end portion 34b is solidly pressed against the tooth, with which it is engaged, of the rack section 33a to restrict the retreat of the plunger 33. [0027] The restriction of retreat of the plunger 33 is effected for every stroke, between adjacent teeth of the rack .section 33a, of the plunger 33. Namely, the lifter 31 is of a ratchet type in which retreating of the plunger 33 is restricted every time the plunger 33 advances a predetermined length of stroke toward the tensioner arm 24. [0028] The plunger 33 keeps pushing the tensioner arm 24 toward the cam chain 14 using the pushing force of the coil spring 36 so that the tensioner arm 24 is kept in rubbing contact with the cam chain 14 to give a predetermined amount of tension to the cam chain 14. With the ratchet claw 34 restricting retreating of the plunger 33, swaying of the cam chain 14 while the engine is running is restrained. [0029] The pressure receiving part 28 is formed in a portion facing the plunger 33 of the back coat layer 21 such that it bulges rearward (toward the plunger 33) making the back coat layer 27 thicker in the portion than in the other portions. [0030], The pressure receiving part 28 has a flat portion 28a formed approximately perpendicularly to the plunger axis C3. For ‘example, a pressure bearing metal plate 28b is provided integrally with and along the flat portion 28a. The front end of the plunger 33 abuts on The pressure bearing plate 28b and presses the tensioner arm 2 4. This configuration may be altered not to include the pressure bearing plate 28b so that the front end of the plunger 33 abuts directly on the pressure receiving part 28. [0031] The pressure receiving part 28 has, for example, plural lightening holes 29 formed laterally through it (extending perpendicularly to the plunger axis C3). Each of the lightening holes 29 is a through-hole having a circular cross section as viewed from a side. The plural lightening holes 29 cause the pressure receiving part 28 to be lower in stiffness than the other parts of the back coat layer 27, so that the pressure receiving part 28 as a whole can appropriately bend when pressed by the plunger 33. The plural lightening holes 29 formed through the pressure receiving part 28 may be replaced by an appropriate lightening recess to be formed on an outside surface of the pressure receiving part 28 (i.e., a recess formed not through the pressure receiving part 28). [0032] As described above, the tensioner device 23 of the above embodiment includes the tensioner arm 24 disposed along the cam chain 14 and the lifter 31 having the plunger 33 that presses the tensioner arm 24 toward the cam chain 14. In the tensioner device 23, the pressure receiving part 28 that is included in the tensioner arm 24 and that is pressed by the plunger 33 has the lightening holes 29. [0033] In the above configuration, the stiffness of the pressure receiving part 28 that is included in the tensioner arm 24 and that is pressed by the plunger 33 is reduced to provide the pressure receiving part 28 with cushioning ability without using any separate cushioning part. This makes it possible to suppress the generation of hitting sound between the tensioner arm 24 and the plunger 33 without increasing the number of parts of the tensioner device and complicating the tensioner device manufacturing process. [0034] The tensioner arm 24 included in the tensioner device 23 has the metallic plate-like core part 25, the chain rubbing layer 26, and the back coat layer 27, the chain rubbing layer 26 and the back coat layer 27 being formed, integrally with the plate-like core part 25, on the front and back sides of the plate-like core part 25, respectively, and each being formed of a plate-like rubber member (or a plate-like resin member). The pressure receiving part 28 is formed of a portion of the back coat layer 27, the portion bulging toward the plunger 33. [0035] The above configuration allows the lightening holes 29 to be formed easily through the pressure receiving part 28. With the lightening holes 29 allowing the pressure receiving part 28 to bend easily, the plunger 33 can be kept pressing and abutting on the pressure receiving part 28. Since the easily bendable pressure receiving part 28 can absorb a play (backlash) in the stroke direction of the plunger 33, the swaying of the tensioner arm 24 and the generation of the hitting sound, both of which can result from a play of the plunger 33, can be suppressed. [0036] Furthermore, the tensioner device 23 is of a ratchet type in which retreating of the plunger 33 is restricted every time the lifter 31 advances the plunger 33 by a predetermined length of stroke toward the tensioner arm 24. In this arrangement, too, the bendability of the pressure receiving part 28 allows the plunger 33 to advance a predetermined length of stroke. Thus, the plunger 33 can be prevented from generating a play in the stroke direction, so that the swaying of the tensioner arm 24 and the generation of the hitting sound, both of which can result from a play of the plunger 33, can be suppressed. [0037] In the tensioner device 23, the lightening holes 29 are formed through the pressure receiving part 28, the lightening holes 29 each having a circular cross section. The lightening holes 29 can, therefore, be easily formed even after the back coat layer 27 is formed. The circular cross-sectional shape of the lightening holes 29 allows the durability of the pressure receiving part 28 to be maintained appropriately. [0038] The present invention is not limited to the above embodiment. For example, the configuration of the tensioner device 23 may be modified such that the pressure receiving part 28 includes, instead of the lightening holes 29, plural slit holes 129 formed laterally through the pressure receiving part 28 as shown in FIG. 3. The slit holes 129 may be formed to extend adequately long along the flat portion 28a. The slit holes 129 as described above enable the pressure receiving part 28 to bend in a more preferred manner when pressed by the plunger 33. The pressure receiving part 28 may include plural external slit grooves instead of the slit holes 129. Furthermore, the pressure receiving part 28 may be made to show a different loading characteristic between when it is pressed by the plunger 33 and when it presses the plunger 33 so as to reduce the hitting sound generated between it and the plunger 33. [0039] The invention may also be applied to an OHC engine in which intake and exhaust valves are opened and closed using a single cam shaft or a multiple cylinder engine, for example, a parallel type engine or a V-type engine. Furthermore, the invention can also be applied to a tensioner device using an endless transmission member other than a cam chain, for example, a belt or to a tensioner device using an endless transmission member which drives an element other than a cam shaft, for example, a pump or a balancer. The configuration of the above embodiment represents only an example of application of the invention, and it can be modified in various ways without departing from the scope of the invention. [Brief Description of the Drawings] [0040] [FIG. 1] is a right side view showing a partial cross section of the engine according to an embodiment of the invention. [FIG. 2] is an enlarged view of an essential part of FIG. 1. [FIG. 3] is an enlarged view of an essential part of a modification of the above embodiment, the essential part corresponding to that shown in FIG. 2. [Description of Reference Numerals] [0041] 1... Engine 14... Cam chain (endless transmission member) 23... Tensioner device 24... Tensioner arm 25... Plate-like core part 26... Chain rubbing layer (transmission member rubbing part) 27... Back coat layer (back coat part) 28... Pressure receiving part 29... Lightening hole (lightening portion) 31... Lifter 3 3... Plunger 129... Slit hole (lightening portion) [Document Name] Scope of Claims [Claim 1] A tensioner device, comprising a tensioner arm disposed along an endless transmission member and a lifter having a plunger which presses the tensioner arm toward the endless transmission member, wherein a pressure receiving part which is included in the tensioner arm and which is pressed by the plunger has a lightening portion. [Claim 2] The tensioner device according to Claim 1, wherein: the tensioner arm comprises a metallic plate-like core part, a transmission member rubbing part formed on a front side of and integrally with the metallic plate-like core part, and a back coat part formed on a back side of and integrally with the metallic plate-like core part, the transmission member rubbing part and the back coat part each being formed of one of a plate-like rubber member and a plate-like resin member; and the pressure receiving part is formed of a portion of the back coat part, the portion bulging toward the plunger. [Claim 3] The tensioner device according to one of Claims 1 and 2, wherein the tensioner device is of a ratchet type in which retreating of the plunger is restricted every time the lifter advances the plunger by a predetermined length of stroke toward the tensioner arm. [Claim 4] The tensioner device according to one of Claims 1 to 3, wherein the lightening portion is a circular hole formed through the pressure receiving part.

Documents:

1597-CHE-2008 CORRESPONDENCE OTHERS 08-05-2014.pdf

1597-CHE-2008 AMENDED CLAIMS 10-01-2014.pdf

1597-CHE-2008 AMENDED CLAIMS 20-08-2014.pdf

1597-CHE-2008 CORRESPONDENCE OTHERS 11-03-2014.pdf

1597-CHE-2008 CORRESPONDENCE OTHERS 20-08-2014.pdf

1597-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 10-01-2014.pdf

1597-CHE-2008 FORM-1 11-03-2014.pdf

1597-CHE-2008 FORM-13 20-08-2014.pdf

1597-CHE-2008 FORM-3 10-01-2014.pdf

1597-CHE-2008 OTHER PATENT DOCUMENT 10-01-2014.pdf

1597-CHE-2008 POWER OF ATTORNEY 10-01-2014.pdf

1597-che-2008 abstract.jpg

1597-che-2008 abstract.pdf

1597-che-2008 claims.pdf

1597-che-2008 correspondence-others.pdf

1597-che-2008 description (complete).pdf

1597-che-2008 drawings.pdf

1597-che-2008 form-1.pdf

1597-che-2008 form-18.pdf

1597-che-2008 form-3.pdf

1597-che-2008 form-5.pdf

1597-che-2008 others.pdf

1597-CHE-2008-Petition for POR.pdf

1597-CHE-2008_8(2).pdf

1597-CHE-2008_Form 13.pdf