Hydraulic tensioner, internal combustion engine, and straddled vehicle

Abstract

To provide a hydraulic tensioner which can desirably perform both air venting from a hydraulic chamber and oil filling into the hydraulic chamber.SOLUTION: A hydraulic tensioner (20) includes: a tensioner body (23) having a through hole (23a) formed therein; a bottomed cylindrical plunger (24) inserted into the through hole of the tensioner body so that the cylindrical plunger is movable in an axial direction of the through hole; a cylindrical inner sleeve (25) inserted into the plunger; and a tensioner cap (26) attached to one end of the tensioner body and having a first surface (26a) in contact with a proximal end of the inner sleeve. A first hydraulic chamber (HC1) is formed between the inner sleeve and the plunger, and a second hydraulic chamber (HC2) that stores oil to be supplied to the first hydraulic chamber is formed inside the inner sleeve. The first surface of the tensioner cap has a plurality of grooves (26c, 26d) each of which allows communication between the outside of the inner sleeve in a radial direction and the second hydraulic chamber.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a hydraulic tensioner, an internal combustion engine, and a saddle-type vehicle. [Background technology]

[0002] Conventionally, there has been known an internal combustion engine equipped with a tensioner that applies tension to a cam chain by pressing the cam chain. An example of the tensioner is a mechanical tensioner. A mechanical tensioner is disclosed in, for example, Patent Document 1.

[0003] The tensioner disclosed in Patent Document 1 includes a first shaft including a first threaded portion, a second shaft including a second threaded portion that screws into the first threaded portion, and a spring that rotationally biases the first shaft. As the second shaft moves in the axial direction in response to the rotation of the first shaft, the second shaft presses the cam chain via a pressing member, thereby applying tension to the cam chain. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-148132 A Summary of the Invention [Problem to be solved by the invention]

[0005] Hydraulic tensioners are also known as tensioners. Hydraulic tensioners are generally superior to mechanical tensioners in terms of suppressing abnormal noise and durability. With hydraulic tensioners, it is necessary to properly bleed air from the hydraulic chamber and fill the hydraulic chamber with oil. If these are not properly performed, there is a risk that the tensioner's pressing force will be insufficient (i.e., the cam chain will not be subjected to sufficient pressure). Insufficient pressing force from the tensioner will cause mechanical noise due to deterioration of the cam chain's behavior.

[0006] An embodiment of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide a hydraulic tensioner that can effectively both bleed air from the hydraulic chamber and fill the hydraulic chamber with oil. [Means for solving the problem]

[0007] This specification discloses a hydraulic tensioner, an internal combustion engine, and a saddle-type vehicle as described in the following items.

[0008] [Item 1] A hydraulic tensioner that applies tension to an endless transmission member wrapped around a crankshaft and a camshaft of an internal combustion engine, a tensioner body having a through hole; a plunger having a bottom and a cylindrical shape and inserted into the through hole of the tensioner body so as to be movable in an axial direction of the through hole; A cylindrical inner sleeve inserted inside the plunger; a tensioner cap attached to one end of the tensioner body, the tensioner cap having a first surface that contacts a base end of the inner sleeve; Equipped with a first hydraulic chamber is formed between the inner sleeve and the plunger, and a second hydraulic chamber for storing oil supplied to the first hydraulic chamber is formed inside the inner sleeve; a first surface of the tensioner cap having a plurality of grooves each of which connects a radial outside of the inner sleeve with the second hydraulic chamber;

[0009] In the hydraulic tensioner according to the embodiment of the present invention, the surface (first surface) of the tensioner cap that contacts the base end of the inner sleeve has a plurality of grooves that each connect the radial outside of the inner sleeve to the second hydraulic chamber, so that the escape of air from the second hydraulic chamber, which is the internal space of the inner sleeve, and the inflow of oil into the second hydraulic chamber are separated. Therefore, air can be smoothly bled from the second hydraulic chamber and oil can be smoothly filled into the second hydraulic chamber. In contrast, if the first surface of the tensioner cap has only one groove that connects the radial outside of the inner sleeve to the second hydraulic chamber, the escape of air from the second hydraulic chamber and the inflow of oil into the second hydraulic chamber are not separated, so that air is difficult to escape from the second hydraulic chamber and oil tends to become clogged, making it difficult for oil to flow into the second hydraulic chamber.

[0010] According to the embodiment of the present invention, air can be effectively bled from the second hydraulic chamber and oil can be effectively filled into the second hydraulic chamber, which prevents air from entering the first hydraulic chamber. This prevents a lack of tensioner pressure (which can cause mechanical noise due to deterioration of the cam chain behavior).

[0011] [Item 2] the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, Among the plurality of grooves, a groove that is located at the lowest position when the internal combustion engine is operating is called a first groove, a portion on the first surface where the oil supply passage intersects with a projection of an outer circumferential edge of the plunger onto the first surface is called a first intersecting portion, When a portion on the first surface where a groove among the plurality of grooves other than the first groove intersects with a projection of the outer circumferential edge of the plunger onto the first surface is referred to as a second intersecting portion, 2. The hydraulic tensioner according to item 1, wherein a portion of a base end of the inner sleeve that overlaps with the first groove in a plan view seen in the axial direction is located lower than the first intersecting portion and the second intersecting portion when the internal combustion engine is operating.

[0012] The lowest groove among the multiple grooves in the tensioner cap is referred to as the "first groove," the portion on the first surface where the oil supply passage intersects with the projection of the outer peripheral edge of the plunger onto the first surface is referred to as the "first intersection portion," and the portion on the first surface where a groove among the multiple grooves other than the first groove intersects with the projection of the outer peripheral edge of the plunger onto the first surface is referred to as the "second intersection portion." It is preferable that the portion of the base end of the inner sleeve that overlaps with the first groove in a plan view from the axial direction is located lower than the first intersection portion and the second intersection portion when the internal combustion engine is operating.

[0013] As a result, when the oil supplied from the oil pump has not yet reached the vicinity of the tensioner, such as when the internal combustion engine is restarted, the oil that leaks out from the leakage gap of the tensioner (the gap between the inner circumferential surface of the plunger and the outer circumferential surface of the inner sleeve) and accumulates on the outside of the inner sleeve can be made to overcome the end face of the inner sleeve and be resupplied to the inside of the inner sleeve (i.e., the second hydraulic chamber), thereby preventing air from entering the first hydraulic chamber. This makes it possible to extend the load retention time and prevent a shortage of the pressing force of the tensioner when the internal combustion engine is restarted, etc.

[0014] [Item 3] the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, Among the plurality of grooves, a groove that is located at the lowest position when the internal combustion engine is operating is called a first groove, a portion on the first surface where the oil supply passage intersects with a projection of an outer circumferential edge of the plunger onto the first surface is called a first intersecting portion, When a portion on the first surface where a groove among the plurality of grooves other than the first groove intersects with a projection of the outer circumferential edge of the plunger onto the first surface is referred to as a second intersecting portion, 3. The hydraulic tensioner according to item 1 or 2, wherein the second intersection portion is located at a higher position than the first intersection portion when the internal combustion engine is operating.

[0015] The lowest groove among the multiple grooves in the tensioner cap is called the "first groove," the portion on the first surface where the oil supply passage intersects with the projection of the outer circumferential edge of the plunger onto the first surface is called the "first intersection portion," and the portion on the first surface where a groove among the multiple grooves other than the first groove intersects with the projection of the outer circumferential edge of the plunger onto the first surface is called the "second intersection portion." It is preferable that the second intersection portion be located higher than the first intersection portion when the internal combustion engine is in operation. This allows air to be bled more efficiently from the second hydraulic chamber.

[0016] [Item 4] 4. The hydraulic tensioner according to any one of items 1 to 3, wherein at least one of the plurality of grooves overlaps with an uppermost point of the base end of the inner sleeve when the internal combustion engine is operating, in a plan view seen from the axial direction.

[0017] When at least one groove of the tensioner cap overlaps with the uppermost point of the base end of the inner sleeve in a plan view, air remaining in or mixed in the second hydraulic chamber tends to spontaneously escape.

[0018] [Item 5] 5. The hydraulic tensioner according to any one of items 1 to 4, wherein at least one of the plurality of grooves overlaps, in a plan view seen from the axial direction, with a lowest point of the base end of the inner sleeve when the internal combustion engine is operating.

[0019] When at least one groove in the tensioner cap overlaps with the lowest point of the base end of the inner sleeve in a planar view, oil supplied from outside the inner sleeve overcomes the end face of the inner sleeve even at a relatively low oil level, making it easier for the oil to flow into the second hydraulic chamber.

[0020] [Item 6] a biasing member disposed inside the first hydraulic chamber and biasing the plunger toward the endless transmission member; a check valve unit disposed between the first hydraulic chamber and the second hydraulic chamber; 6. The hydraulic tensioner of any of items 1 to 5, further comprising:

[0021] [Item 7] the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, 7. The hydraulic tensioner according to any one of items 1 to 6, wherein the oil supply passage and the plurality of grooves are continuous with each other.

[0022] If the oil supply passage and the plurality of grooves are continuous with each other, there is an advantage that the oil supplied from the oil pump reaches the second hydraulic chamber more quickly when the internal combustion engine is restarted.

[0023] [Item 8] the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, 7. The hydraulic tensioner according to any one of items 1 to 6, wherein the oil supply passage and the plurality of grooves are separated from each other.

[0024] When the oil supply passage and the multiple grooves are separated from each other, the oil supplied to the outside of the inner sleeve (the space surrounded by the inner surface of the plunger hole, the outer surface of the inner sleeve, and the base end (upper end) of the plunger) has the advantage that the oil supplied to the outside of the inner sleeve and the air mixed therein can be easily separated.

[0025] [Item 9] 9. The hydraulic tensioner of any of items 1 to 8, wherein the plurality of grooves includes two grooves that are continuous with each other.

[0026] If the two grooves are continuous with each other, there is no air pocket in the discontinuous portion between the grooves, which provides the advantage that oil can be supplied to the second hydraulic chamber more smoothly.

[0027] [Item 10] 9. The hydraulic tensioner of any of items 1 to 8, wherein the plurality of grooves includes two grooves that are separated from each other.

[0028] The advantage of the two grooves being separated from each other is that when the internal combustion engine is restarted, the oil that has accumulated on the outside of the inner sleeve (in the space mentioned above) is prevented from passing through the top of the second hydraulic chamber and being discharged directly through the air vent hole in the tensioner body.

[0029] [Item 11] 11. An internal combustion engine comprising a hydraulic tensioner according to any one of items 1 to 10.

[0030] [Item 12] Item 12. A saddle-type vehicle equipped with the internal combustion engine according to item 11. Effect of the Invention

[0031] According to an embodiment of the present invention, a hydraulic tensioner is provided that can suitably both bleed air from the hydraulic chamber and fill the hydraulic chamber with oil. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a left side view showing a motorcycle 100 in schematic form. [Figure 2A] 1 is a left side view showing an engine 1 and its vicinity provided in a motorcycle 100. FIG. [Figure 2B]FIG. 2 is a top view showing the engine 1 and its surroundings. [Diagram 3] FIG. 2 is a diagram showing the inside of the engine 1. [Figure 4] FIG. 2 is a top view showing a schematic diagram of the tensioner 20. [Diagram 5] 5A is a cross-sectional view showing a schematic cross section of the tensioner 20 taken along line 5A-5A' in FIG. [Figure 6] 6 is a cross-sectional view showing a schematic cross section of the tensioner 20 taken along line 6A-6A' in FIG. [Figure 7] FIG. 2 is a perspective view showing a schematic view of the tensioner 20, with the tensioner 20 being partially cut away. [Figure 8] 2 is a perspective view of the tensioner cap 26 as seen from the back side. [Figure 9] FIG. 2 is a top view showing a schematic diagram of the tensioner 20. [Figure 10] 2 is a top view showing a schematic diagram of the tensioner 20, illustrating another example of the configuration of the tensioner 20. FIG. [Figure 11] FIG. 11 is a cross-sectional view taken along line 11A-11A' in FIG. [Figure 12] 2 is a top view showing a schematic diagram of the tensioner 20, illustrating yet another example of the configuration of the tensioner 20. FIG. [Figure 13] FIG. 13 is a cross-sectional view taken along line 13A-13A' in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] A saddle-type vehicle according to an embodiment of the present invention will be described below with reference to the drawings. A saddle-type vehicle is a vehicle on which a rider straddles and rides. In the following description, a motorcycle is exemplified as a saddle-type vehicle according to an embodiment of the present invention. The type of motorcycle is not limited in any way, and may be any type such as a so-called scooter type, moped type, off-road type, or on-road type. In addition, the saddle-type vehicle according to an embodiment of the present invention is not limited to a motorcycle, and may be an ATV (All Terrain Vehicle), a four-wheeled buggy, or the like.

[0034] The overall configuration of a motorcycle 100 in this embodiment will be described with reference to FIG. 1. FIG. 1 is a left side view showing the motorcycle 100. In the following description, front, rear, left, right, top, and bottom respectively refer to the front, rear, left, right, top, and bottom as seen by a rider seated on the seat of the motorcycle 100. Top and bottom respectively refer to the top and bottom in the vertical direction when the motorcycle 100 is stopped on a horizontal plane. The above directions are also used when describing each part of the engine. Therefore, the front, rear, left, right, top, and bottom of the engine refer to the front, rear, left, right, top, and bottom when the engine is mounted on the motorcycle 100.

[0035] As shown in FIG. 1, the motorcycle 100 comprises a body frame 102 including a head pipe 101, a seat 103 supported by the body frame 102, an engine (internal combustion engine) 1 supported by the body frame 102, a handlebar 104 rotatably supported on the head pipe 101, a front wheel 105, and a rear wheel 106 driven by the engine 1.

[0036] The configuration of engine 1 will be described with reference to Figures 2A and 2B. Figures 2A and 2B are a left side view and a top view, respectively, showing engine 1 and its vicinity. Note that the front, rear, left, right, top, and bottom shown in Figures 2A and 2B refer to the front, rear, left, right, top, and bottom when engine 1 is mounted on motorcycle 100.

[0037] The engine 1 is a four-stroke water-cooled engine and includes a crankcase 2, a cylinder body 3, a cylinder head 4, and a cylinder head cover 5, as shown in Figures 2A and 2B.

[0038] The crankcase 2 houses a crankshaft 6. The crankshaft 6 extends in the left-right direction. On the left side of the crankcase 2, a transmission case 7 that houses a transmission (for example, a CVT (Continuously Variable Transmission)) is disposed.

[0039] The cylinder body 3 is disposed in front of the crankcase 2. The cylinder body 3 is joined to a front portion of the crankcase 2.

[0040] The cylinder head 4 is disposed in front of the cylinder body 3. The cylinder head 4 is coupled to a front portion of the cylinder body 3.

[0041] The cylinder head cover 5 is disposed in front of the cylinder head 4. The cylinder head cover 5 is joined to the front portion of the cylinder head 4.

[0042] A valve mechanism including an intake valve, an exhaust valve, a camshaft, etc. (none of which are shown in FIG. 2) is provided within the cylinder head 4 and the cylinder head cover 5.

[0043] A cylinder (not shown) is formed inside the cylinder body 3. The cylinder extends along a cylinder axis CA. The cylinder axis CA is inclined significantly forward with respect to the vertical direction (up-down direction). In other words, the cylinder extends forward from the crankcase 2. Note that "forward" here has a broad meaning and includes both cases where the cylinder extends horizontally forward and cases where the cylinder is inclined from the horizontal direction. Note that, although the engine 1 is a single-cylinder engine having one cylinder, it may be a multi-cylinder engine having multiple cylinders.

[0044] A piston (not shown) is housed in the cylinder, and the piston is connected to a crankshaft 6 via a connecting rod (not shown). The cylinder body 3 and the crankcase 2 may be formed separately or integrally.

[0045] An intake passage section 10 is connected to the cylinder head 4 of the engine 1. The intake passage section 10 is disposed above the engine 1. The intake passage section 10 includes an intake duct 11 connected to the cylinder head 4 and extending rearward from an upper surface 4a of the cylinder head 4, a throttle body 12 provided midway through the intake duct 11, an air cleaner (not shown) connected to the intake duct 11, and the like.

[0046] 2A and 2B, the engine 1 further includes a hydraulic tensioner (hereinafter simply referred to as a "tensioner") 20. The tensioner 20 is disposed on an upper portion of the cylinder body 3.

[0047] Fig. 3 is a diagram showing the inside of the engine 1. As shown in Fig. 3, inside the engine 1, a cam chain 9 is wound around the crankshaft 6 and the camshaft 8 (more precisely, around a chain drive sprocket 6S attached to the crankshaft 6 and a cam sprocket 8S attached to the camshaft 8). A tensioner 20 applies tension to the cam chain 9. The cam chain 9 is an example of an endless transmission member. Instead of the cam chain 9, another endless transmission member (for example, a cam belt) may be used.

[0048] The tensioner 20 includes a chain guide 21 that comes into contact with the cam chain 9 and a tensioner lifter 22 that presses the chain guide 21 against the cam chain 9.

[0049] An oil pump 40 is disposed in the crankcase 2. The oil pump 40 is connected to and driven by the crankshaft 6. Oil is supplied to the tensioner 20 from the oil pump 40 via an oil passage 41. The oil passage 41 is formed to extend from the crankcase 2 to the cylinder body 3. Although not shown here, a cylinder gasket is disposed between the crankcase 2 and the cylinder body 3, and a portion 41a of the oil passage 41 located between the crankcase 2 and the cylinder body 3 passes through a through hole formed in the cylinder gasket.

[0050] The structure of the tensioner 20 will be described in more detail with reference to Figures 4 to 7. Figure 4 is a top view showing the tensioner 20. Figures 5 and 6 are cross-sectional views showing the tensioner 20, respectively taken along lines 5A-5A' and 6A-6A' in Figure 4. Figure 7 is a perspective view showing the tensioner 20, with a portion of the tensioner 20 cut away. The chain guide 21 is omitted from Figures 4 to 7.

[0051] As shown in FIGS. 4 to 7, the tensioner lifter 22 of the tensioner 20 includes a tensioner body 23, a plunger 24, an inner sleeve 25, and a tensioner cap 26.

[0052] A through hole (hereinafter referred to as a "plunger hole") 23a is formed in the tensioner body 23. The plunger hole 23a extends in a direction slightly tilted backward from the up-down direction (vertical direction) as shown in FIG. 5. The lower end of the plunger hole 23a opens into the engine 1 (inside the cylinder body 3). The tensioner body 23 is formed integrally with the cylinder body 3. It can also be said that a part of the cylinder body 3 functions as the tensioner body 23. The tensioner body 23 may be a separate body from the cylinder body 3.

[0053] The plunger 24 is tubular with one end closed, that is, tubular with a bottom (more specifically, cylindrical with a bottom). The plunger 24 has an end wall 24a located at the tip (lower end) and a peripheral wall 24b extending from the periphery of the end wall 24a. The plunger 24 is inserted into the plunger hole 23a of the tensioner body 23 so as to be movable in the axial direction of the plunger hole 23a. The tip (end wall 24a) of the plunger 24 protrudes from the lower end of the tensioner body 23 into the cylinder body 3 (more specifically, into the cam chain chamber) and abuts against the chain guide 21.

[0054] The inner sleeve 25 is tubular (more specifically, cylindrical). The inner sleeve 25 has an end wall 25a located at the tip (lower end) and a peripheral wall 25b extending from the periphery of the end wall 25a. A through hole (oil hole) 25c is formed in the end wall 25a. A recess 25d is formed in the lower surface of the end wall 25a. The inner sleeve 25 is inserted inside the plunger 24. An annular groove 25e is formed in the outer circumferential surface of the inner sleeve 25, and a circlip 27 is attached to the annular groove 25e.

[0055] The tensioner cap 26 is attached to one end (here, the upper end) of the tensioner body 23. In the example shown in the figure, the tensioner cap 26 is attached to the tensioner body 23 by a plurality of bolts 28. A lower surface 26a of the tensioner cap 26 contacts the base end (upper end) of the inner sleeve 25. A tensioner gasket 29 is disposed between the tensioner cap 26 and the tensioner body 23.

[0056] The tensioner 20 has a first hydraulic chamber (high pressure chamber) HC1 and a second hydraulic chamber (low pressure chamber) HC2. The first hydraulic chamber HC1 is formed between the inner sleeve 25 and the plunger 24. The second hydraulic chamber HC2 is formed inside the inner sleeve 25. The second hydraulic chamber HC2 stores oil to be supplied to the first hydraulic chamber HC1. The second hydraulic chamber HC2 is in communication with the first hydraulic chamber HC1 via an oil hole 25c.

[0057] A coil spring 31 is disposed inside the first hydraulic chamber HC1. The coil spring 31 biases the plunger 24 toward the cam chain 9 (endless transmission member). That is, the elastic force of the coil spring 31 presses the end wall 24a of the plunger 24 against the chain guide 21. The elastic force of the coil spring 31 also acts to press the base end of the inner sleeve 25 against the tensioner cap 26. The coil spring 31 is an example of a biasing member. Instead of the coil spring 31, a biasing member other than the coil spring 31 may be used.

[0058] In addition, a check valve unit 32 is disposed between the first hydraulic chamber HC1 and the second hydraulic chamber HC2. The check valve unit 32 has a function of allowing oil in the second hydraulic chamber HC2 to flow in one direction (from the second hydraulic chamber HC2 to the first hydraulic chamber HC1) by opening and closing the oil hole 25c. In other words, the check valve unit 32 prevents oil from flowing back from the first hydraulic chamber HC1 to the second hydraulic chamber HC2.

[0059] The check valve unit 32 includes a check valve 33 , a valve seat 34 and a check spring 35 .

[0060] The check valve 33 is provided so as to be able to come into close contact with the lower edge of the oil hole 25c. The check valve 33 is a ball valve in this embodiment.

[0061] The valve seat 34 is disposed in the recess 25d of the end wall 25a and accommodates the check valve 33. The valve seat 34 has a cup portion 34a formed in a cup shape and a flange portion 34b extending radially outward from the periphery of the opening side of the cup portion 34a. A plurality of small holes (not shown) through which oil passes are formed in the cup portion 34a.

[0062] The check spring 35 is disposed within the valve seat 34, and biases the check valve 33 upward (toward the second hydraulic chamber HC2). The check spring 35 is a coil spring here.

[0063] The tensioner body 23 is formed with an oil supply hole 51 and an air vent hole 52. The oil supply hole 51 constitutes a part of the oil passage 41 extending from the oil pump 40, and is a hole through which the oil supplied to the second hydraulic chamber HC2 passes. The oil supply hole 51 includes a portion extending in the vertical direction. In FIG. 7, the flow of oil in the tensioner 20 is indicated by a hollow arrow. The air vent hole 52 is a hole for venting air to the outside of the tensioner 20, and penetrates the tensioner body 23 in the vertical direction. In FIG. 7, the flow of air is indicated by a hatched arrow. In addition, the tensioner gasket 29 has through holes 29a and 29b that overlap the oil supply hole 51 and the air vent hole 52, respectively, in a plan view seen from the axial direction of the plunger hole 23a. In the following description, "plan view" means "plan view seen from the axial direction of the plunger hole 23a" unless otherwise specified.

[0064] Here, the structure of the tensioner cap 26 will be described with further reference to Fig. 8. Fig. 8 is a perspective view of the tensioner cap 26 as seen from the back side.

[0065] The lower surface 26a of the tensioner cap 26 has a groove-shaped oil supply passage 26b. As shown in FIG. 4 and other figures, the oil supply passage 26b extends from the outside to the inside of the outer circumferential edge of the plunger 24 (which almost overlaps with the inner circumferential surface of the plunger hole 23a) in a plan view. More specifically, the oil supply passage 26b overlaps with the second hydraulic chamber HC2 and the oil supply hole 51 in a plan view, and communicates the second hydraulic chamber HC2 with the oil supply hole 51. The oil supply passage 26b also overlaps with the space S1 surrounded by the inner circumferential surface of the plunger hole 23a, the outer circumferential surface of the inner sleeve 25, and the base end (upper end) of the plunger 24. In the illustrated example, the oil supply passage 26b extends almost along the left-right direction.

[0066] The lower surface 26a of the tensioner cap 26 further has a plurality of grooves 26c and 26d. Each of the plurality of grooves 26c and 26d communicates the radial outside of the inner sleeve 25 with the second hydraulic chamber HC2. In the illustrated example, the grooves 26c and 26d are continuous (it can also be said that the grooves 26c and 26d are integrally formed to form a single groove as a whole), but as described below, the grooves 26c and 26d may be separated. In the illustrated example, the grooves 26c and 26d extend substantially along the front-rear direction.

[0067] One 26c of grooves 26c and 26d is located lower than the other 26d when the engine 1 is in operation (see FIG. 5). Hereinafter, groove 26c located relatively lower will also be referred to as the "first groove," and groove 26d located relatively higher will also be referred to as the "second groove."

[0068] As already described, the first groove 26c and the second groove 26d each communicate between the radial outside of the inner sleeve 25 and the second hydraulic chamber HC2. More specifically, the first groove 26c extends so as to overlap with the space S1 and the second hydraulic chamber HC2 in a plan view, thereby communicating the space S1 with the second hydraulic chamber HC2. The second groove 26d extends so as to overlap with the second hydraulic chamber HC2 and the air vent hole 52 in a plan view, thereby communicating the second hydraulic chamber HC2 with the air vent hole 52.

[0069] In the illustrated example, the oil supply passage 26b is continuous with the first groove 26c and the second groove 26d, but as described below, the oil supply passage 26b may be separated from the first groove 26c and the second groove 26d.

[0070] The tensioner cap 26 also has a plurality of bolt holes 26e. Bolts 28 are inserted through the bolt holes 26e.

[0071] The tensioner 20 having the above-described configuration operates as follows.

[0072] When the engine 1 starts, the oil pump 40 operates and supplies the stored oil to the tensioner 20 via an oil passage 41. Note that the oil pump 40 can also supply oil to other parts of the engine 1.

[0073] 7, oil supplied to the oil supply hole 51 of the tensioner body 23 flows into the second hydraulic chamber HC2 through the oil supply passage 26b of the tensioner cap 26. The oil supplied to the oil supply hole 51 also flows into the space S1 through the oil supply passage 26b. Since the space S1 extends in the circumferential direction of the plunger hole 23a, the oil that has flowed into the space S1 flows into the second hydraulic chamber HC2 through the first groove 26c of the tensioner cap 26.

[0074] In the second hydraulic chamber HC2, the pressure increases due to the flow of oil, so the check valve 33 of the check valve unit 32 moves away from the edge of the oil hole 25c, and the oil in the second hydraulic chamber HC2 flows into the first hydraulic chamber HC1 through the oil hole 25c. As a result, the pressure in the first hydraulic chamber HC1 gradually increases. This increase in pressure and the biasing force of the coil spring 31 cause the plunger 24 to move down and press the chain guide 21 against the cam chain 9. This applies tension to the cam chain 9.

[0075] At this time, when the plunger 24 is pushed back by the movement of the cam chain 9 and the volume of the first hydraulic chamber HC1 decreases, some of the oil in the first hydraulic chamber HC1 passes through the gap between the inner circumferential surface of the plunger 24 and the outer circumferential surface of the inner sleeve 25 (hereinafter sometimes referred to as the "leak gap"), and further passes through the space S1 and the gap between the outer circumferential surface of the plunger 24 and the inner circumferential surface of the plunger hole 23a, and flows out into the cam chain chamber. The oil that has flowed out into the cam chain chamber drops into the chain guide 21, and lubricates the cam chain 9, the sliding portion between the cam chain 7 and the chain guide 21, the contact portion between the chain guide 21 and the plunger 24, etc.

[0076] When the plunger 24 is pushed back, the force pushing the plunger 24 back is attenuated by the pressure in the first hydraulic chamber HC1. Therefore, if the first hydraulic chamber HC1 is not filled with a sufficient amount of oil, the plunger 24 is pushed back too much, preventing the cam chain 9 from receiving the appropriate tension, which may cause noise.

[0077] Furthermore, if air is mixed in the oil supplied to the oil supply hole 51, the air will pass through the second groove 26d of the tensioner cap 26 and the air vent hole 52 of the tensioner body 23 and be discharged into the cam chain chamber.

[0078] As described above, in the tensioner 20 according to the embodiment of the present invention, the lower surface 26a of the tensioner cap 26 (the surface in contact with the base end of the inner sleeve 25) has the first groove 26c and the second groove 26d, each of which connects the radial outside of the inner sleeve 25 with the second hydraulic chamber HC2, and therefore the escape of air from the second hydraulic chamber HC2, which is the internal space of the inner sleeve 25, is separated from the inflow of oil into the second hydraulic chamber HC2. This allows air to be smoothly bled from the second hydraulic chamber HC2 and oil to be filled into the second hydraulic chamber HC2.

[0079] In contrast, if only one groove is formed on the underside 26a of the tensioner cap 26, connecting the radial outside of the inner sleeve 25 with the second hydraulic chamber HC2 (for example, if the first groove 26c is omitted and the oil supply path 26b extends to the space S1 but not to the second hydraulic chamber HC2), the escape of air from the second hydraulic chamber HC2 and the flow of oil into the second hydraulic chamber HC2 are not separated, making it difficult for air to escape from the second hydraulic chamber HC2 and causing the oil to become clogged, making it difficult for oil to flow into the second hydraulic chamber HC2.

[0080] According to the embodiment of the present invention, air can be effectively bled from the second hydraulic chamber HC2 and oil can be effectively filled into the second hydraulic chamber HC2, thereby preventing air from entering the first hydraulic chamber HC1. This makes it possible to prevent a shortage of the pressing force of the tensioner 20 (which can cause mechanical noise due to deterioration of the behavior of the cam chain 9).

[0081] Here, an example of a preferred configuration of tensioner 20 will be described with reference to Fig. 9. Fig. 9 is a top view that shows a schematic diagram of tensioner 20, similar to Fig. 4.

[0082] On the underside 26a of the tensioner cap 26, a portion P1 where the oil supply passage 26b and the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a intersect is called the "first intersection portion," and a portion P2 where the second groove 26d and the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a intersect is called the "second intersection portion."

[0083] In this case, it is preferable that a portion P3 of the base end of the inner sleeve 25 that overlaps with the first groove 26c in a plan view is located lower than the first intersecting portion P1 and the second intersecting portion P2 when the engine 1 is in operation.

[0084] If the portion P3 of the base end of the inner sleeve 25 overlapping with the first groove 26c is located lower than the first intersection portion P1 and the second intersection portion P2, when the oil supplied from the oil pump 40 has not yet reached the vicinity of the tensioner 20, such as when the engine 1 is restarted, the oil leaking from the leak gap (the gap between the inner peripheral surface of the plunger 24 and the outer peripheral surface of the inner sleeve 25) of the tensioner 20 and accumulating on the outside (space S1) of the inner sleeve 25 can be made to overcome the end face of the inner sleeve 25 and resupplied to the inside of the inner sleeve 25 (i.e., the second hydraulic chamber HC2), thereby preventing air from entering the first hydraulic chamber HC1. This allows the load retention time to be extended, thereby preventing a shortage of the pressing force of the tensioner when the engine 1 is restarted, etc.

[0085] It is preferable that the second intersection portion P2 is located higher than the first intersection portion P1 when the engine 1 is in operation, so that air can be more effectively bled from the second hydraulic chamber HC2.

[0086] In the illustrated example, the second groove 26d overlaps in plan view with the uppermost point HP of the base end of the inner sleeve 25 when the engine 1 is operating. When at least one of the multiple grooves 26c and 26d of the tensioner cap 26 overlaps in plan view with the uppermost point HP of the base end of the inner sleeve 25, air remaining in or mixed in the second hydraulic chamber HC2 tends to escape spontaneously.

[0087] In the illustrated example, the first groove 26c overlaps in plan view with the lowest point LP of the base end of the inner sleeve 25 when the engine 1 is operating. When at least one of the multiple grooves 26c and 26d of the tensioner cap 26 overlaps in plan view with the lowest point LP of the base end of the inner sleeve 25, oil supplied from outside the inner sleeve 25 overcomes the end face of the inner sleeve 25 even at a relatively low oil level, making it easier for the oil to flow into the second hydraulic chamber HC2.

[0088] In the above description, an example has been shown in which the oil supply passage 26b, the first groove 26c, and the second groove 26d are continuous with each other, but as shown in Fig. 10 and Fig. 11, the oil supply passage 26b, the first groove 26c, and the second groove 26d may be separated from each other. In the example shown in Fig. 10 and Fig. 11, the oil supply passage 26b extends from the oil supply hole 51 to the space S1, but does not extend to the second hydraulic chamber HC2. Therefore, the oil supplied to the oil supply hole 51 does not flow directly from the oil supply passage 26b to the second hydraulic chamber HC2, but flows into the second hydraulic chamber HC2 via the space S1 and the first groove 26c.

[0089] Separating the oil supply passage 26b from the first groove 26c and the second groove 26d provides the advantage that the oil supplied to the space S1 (outside the inner sleeve 25) and the air mixed therein are easily separated. In contrast, if the oil supply passage 26b is continuous with the first groove 26c and the second groove 26d, the oil supplied from the oil pump 40 reaches the second hydraulic chamber HC2 more quickly when the engine 1 is restarted.

[0090] 12 and 13, the first groove 26c and the second groove 26d may be separated from each other. When the first groove 26c and the second groove 26d are separated from each other, the advantage is obtained that the oil accumulated in the space S1 (outside the inner sleeve 25) is prevented from passing through the upper part of the second hydraulic chamber HC2 and being discharged directly from the air vent hole 52 of the tensioner body 23 when the engine 1 is restarted. In contrast, when the first groove 26c and the second groove 26d are continuous with each other, the air is not accumulated in the discontinuous portion between the grooves (the portion located between the first groove 26c and the second groove 26d in the example shown in FIG. 12 and FIG. 13), so that the oil can be supplied to the second hydraulic chamber HC2 more smoothly.

[0091] In addition to the oil supply passage 26b, the first groove 26c, and the second groove 26d, the lower surface 26a of the tensioner cap 26 may have an additional groove that connects the radial outside of the inner sleeve 25 to the second hydraulic chamber HC2. In other words, three or more grooves that connect the radial outside of the inner sleeve 25 to the second hydraulic chamber HC2 may be formed in the lower surface 26a of the tensioner cap 26.

[0092] As described above, the hydraulic tensioner 20 according to the embodiment of the present invention is a hydraulic tensioner 20 that applies tension to the endless transmission member 9 wound around the crankshaft 6 and camshaft 8 of the internal combustion engine 1, and includes a tensioner body 23 having a through hole 23a formed therein, a bottomed cylindrical plunger 24 inserted into the through hole 23a of the tensioner body 23 so as to be movable in the axial direction of the through hole 23a, a cylindrical inner sleeve 25 inserted inside the plunger 24, and a tensioner cap 26 attached to one end of the tensioner body 23, the tensioner cap 26 having a first surface 26a that contacts a base end of the inner sleeve 25. A first hydraulic chamber HC1 is formed between the inner sleeve 25 and the plunger 24, and a second hydraulic chamber HC2 is formed inside the inner sleeve 25 in which oil to be supplied to the first hydraulic chamber HC1 is stored. The first surface 26a of the tensioner cap 26 has a plurality of grooves 26c, 26d each of which connects the radial outside of the inner sleeve 25 with the second hydraulic chamber HC2.

[0093] In the hydraulic tensioner 20 according to the embodiment of the present invention, the surface (first surface) 26a of the tensioner cap 26 that contacts the base end of the inner sleeve 25 has a plurality of grooves 26c, 26d that each communicate between the radial outside of the inner sleeve 25 and the second hydraulic chamber HC2, so that the escape of air from the second hydraulic chamber HC2, which is the internal space of the inner sleeve 25, and the inflow of oil into the second hydraulic chamber HC2 are separated. Therefore, the escape of air from the second hydraulic chamber HC2 and the filling of oil into the second hydraulic chamber HC2 can be performed smoothly. In contrast, if only one groove that communicates between the radial outside of the inner sleeve 25 and the second hydraulic chamber HC2 is formed on the first surface 26a of the tensioner cap 26, the escape of air from the second hydraulic chamber HC2 and the inflow of oil into the second hydraulic chamber HC2 are not separated, so that it becomes difficult for air to escape from the second hydraulic chamber HC2, and the oil tends to become clogged, making it difficult for oil to flow into the second hydraulic chamber HC2.

[0094] According to the embodiment of the present invention, air can be effectively bled from the second hydraulic chamber HC2 and oil can be effectively filled into the second hydraulic chamber HC2, thereby preventing air from entering the first hydraulic chamber HC1. This makes it possible to prevent a shortage of the pressing force of the tensioner 20 (which can cause mechanical noise due to deterioration of the behavior of the cam chain 9).

[0095] In one embodiment, the first surface 26a of the tensioner cap 26 has a groove-shaped oil supply passage 26b that extends from outside to inside the outer periphery of the plunger 24 in a plan view seen in the axial direction. Of the multiple grooves 26c, 26d, the groove 26c that is located at the lowest position when the internal combustion engine 1 is operating is called the first groove, a portion P1 on the first surface 26a where the oil supply passage 26b intersects with the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a is called the first intersection portion, and a portion P2 on the first surface 26a where a groove 26d other than the first groove 26c among the multiple grooves 26c, 26d intersects with the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a is called the second intersection portion. A portion P3 of the base end of the inner sleeve 25 that overlaps with the first groove 26c in a planar view from the axial direction is located at a lower position than the first intersection portion P1 and the second intersection portion P2 when the internal combustion engine 1 is operating.

[0096] The groove 26c located at the lowest position among the multiple grooves 26c, 26d of the tensioner cap 26 is referred to as the "first groove," a portion P1 on the first surface 26a where the oil supply passage 26b and the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a intersect is referred to as the "first intersection portion," and a portion P2 on the first surface 26a where a groove 26d other than the first groove 26c among the multiple grooves 26c, 26d intersects with the projection of the outer peripheral edge of the plunger 24 onto the first surface 26a is referred to as the "second intersection portion." It is preferable that the portion of the base end of the inner sleeve 25 that overlaps with the first groove 26c in a planar view seen from the axial direction is located lower than the first intersection portion P1 and the second intersection portion P2 when the internal combustion engine 1 is operating.

[0097] As a result, when the oil supplied from the oil pump 40 has not yet reached the vicinity of the tensioner 20, such as when the internal combustion engine 1 is restarted, the oil leaking out from the leakage gap of the tensioner 20 (the gap between the inner circumferential surface of the plunger 24 and the outer circumferential surface of the inner sleeve 25) and accumulating on the outside of the inner sleeve 25 can be made to overcome the end face of the inner sleeve 25 and be re-supplied to the inside of the inner sleeve 25 (i.e., the second hydraulic chamber HC2), thereby preventing air from entering the first hydraulic chamber HC1. This allows the load retention time to be extended, thereby preventing a shortage of the pressing force of the tensioner 20 when the internal combustion engine 1 is restarted, etc.

[0098] In one embodiment, the first surface 26a of the tensioner cap 26 has a groove-shaped oil supply passage 26b that extends from the outside to the inside of the outer circumferential edge of the plunger 24 in a plan view seen from the axial direction. When the groove 26c that is located at the lowest position among the plurality of grooves 26c, 26d when the internal combustion engine 1 is operating is called a first groove, a portion P1 on the first surface 26a where the oil supply passage 26b intersects with a projection of the outer circumferential edge of the plunger 24 onto the first surface 26a is called a first intersection portion, and a portion P2 on the first surface 26a where a groove 26d among the plurality of grooves 26c, 26d other than the first groove 26c intersects with a projection of the outer circumferential edge of the plunger 24 onto the first surface 26a is called a second intersection portion, the second intersection portion P2 is located at a higher position than the first intersection portion P1 when the internal combustion engine 1 is operating.

[0099] The groove 26c at the lowest position among the multiple grooves 26c, 26d of the tensioner cap 26 is called the "first groove", a portion P1 on the first surface 26a where the oil supply passage 26b intersects with the projection of the outer circumferential edge of the plunger 24 onto the first surface 26a is called the "first intersection portion", and a portion P2 on the first surface 26a where a groove 26d other than the first groove 26c among the multiple grooves 26c, 26d intersects with the projection of the outer circumferential edge of the plunger 24 onto the first surface 26a is called the "second intersection portion", it is preferable that the second intersection portion P2 is located higher than the first intersection portion P1 when the internal combustion engine 1 is in operation. This allows air to be bled from the second hydraulic chamber HC2 more effectively.

[0100] In one embodiment, at least one of the multiple grooves 26c, 26d overlaps, in a plan view from the axial direction, the uppermost point HP of the base end of the inner sleeve 25 when the internal combustion engine 1 is operating.

[0101] When at least one groove of the tensioner cap 26 overlaps with the uppermost point HP of the base end of the inner sleeve 25 in a plan view, air remaining in or mixed in the second hydraulic chamber HC2 tends to escape spontaneously.

[0102] In one embodiment, at least one of the multiple grooves 26c, 26d overlaps, in a plan view from the axial direction, the lowest point LP of the base end of the inner sleeve 25 when the internal combustion engine 1 is operating.

[0103] When at least one groove of the tensioner cap 26 overlaps with the lowest point LP of the base end of the inner sleeve 25 in a planar view, the oil supplied from outside the inner sleeve 25 overcomes the end face of the inner sleeve 25 even at a relatively low oil level, making it easier for the oil to flow into the second hydraulic chamber HC2.

[0104] In one embodiment, the hydraulic tensioner 20 further includes a biasing member 31 that is disposed inside the first hydraulic chamber HC1 and biases the plunger 24 toward the endless transmission member 9, and a check valve unit 32 that is disposed between the first hydraulic chamber HC1 and the second hydraulic chamber HC2.

[0105] In one embodiment, the first surface 26a of the tensioner cap 26 has, in a plan view from the axial direction, a groove-shaped oil supply passage 26b extending from outside to inside the outer circumferential edge of the plunger 24, and the oil supply passage 26b and the multiple grooves 26c, 26d are continuous with each other.

[0106] If the oil supply passage 26b and the plurality of grooves 26c, 26d are continuous with each other, there is an advantage that when the internal combustion engine 1 is restarted, the oil supplied from the oil pump 40 reaches the second hydraulic chamber HC2 more quickly.

[0107] In one embodiment, the first surface 26a of the tensioner cap 26 has, in a plan view from the axial direction, a groove-shaped oil supply passage 26b extending from outside to inside the outer circumferential edge of the plunger 24, and the oil supply passage 26b and the multiple grooves 26c, 26d are separated from each other.

[0108] When the oil supply passage 26b and the multiple grooves 26c, 26d are separated from each other, the oil supplied to the outside of the inner sleeve 25 (the space S1 surrounded by the inner surface of the plunger hole 23a, the outer surface of the inner sleeve 25, and the base end (upper end) of the plunger 24) is easily separated from the air mixed therein.

[0109] In one embodiment, the plurality of grooves 26c, 26d includes two grooves 26c, 26d that are continuous with each other.

[0110] If the two grooves 26c, 26d are continuous with each other, there is no air pocket in the discontinuous portion between the grooves, which provides the advantage that oil can be supplied to the second hydraulic chamber HC2 more smoothly.

[0111] In one embodiment, the plurality of grooves 26c, 26d includes two grooves 26c, 26d that are separated from each other.

[0112] If the two grooves 26c, 26d are separated from each other, there is an advantage that, when the internal combustion engine 1 is restarted, the oil that has accumulated on the outside of the inner sleeve 25 (the space S1 described above) is prevented from passing through the upper part of the second hydraulic chamber HC2 and being discharged directly from the air vent hole of the tensioner body 23.

[0113] The internal combustion engine 1 according to the embodiment of the present invention includes a hydraulic tensioner 20 having any of the configurations described above.

[0114] The saddle-type vehicle 100 according to the embodiment of the present invention includes the internal combustion engine 1 having the above-described configuration. [Industrial Applicability]

[0115] According to an embodiment of the present invention, a hydraulic tensioner is provided that can effectively bleed air from a hydraulic chamber and fill the hydraulic chamber with oil. The hydraulic tensioner according to the embodiment of the present invention is preferably used in the internal combustion engines of various saddle-ride type vehicles. [Explanation of symbols]

[0116] 1: engine (internal combustion engine), 2: crankcase, 3: cylinder body, 4: cylinder head, 4a: upper surface of cylinder head, 5: cylinder head cover, 6: crankshaft, 7: transmission case, 8: camshaft, 9: cam chain, 10: intake passage, 11: intake duct, 12: throttle body, 20: hydraulic tensioner, 21: chain guide, 22: tensioner lifter, 23: tensioner body, 23a: through hole (plunger hole), 24: plunger, 24a: end wall, 24b: peripheral wall, 25: inner sleeve, 25a: end wall, 25b: peripheral wall, 25c: through hole (oil hole), 25d: recess, 25e: annular groove, 26: tensioner cap, 26a: lower surface of tensioner cap, 26b: oil supply path, 26c: first groove , 26d: second groove, 26e: bolt hole, 27: circlip, 28: bolt, 29: tensioner gasket, 31: coil spring, 32: check valve unit, 33: check valve, 34: valve seat, 35: check spring, 40: oil pump, 41: oil passage, 51: oil supply hole, 52: air vent hole, 100: motorcycle, 101: head pipe, 102: body frame, 103: seat, 104: handle, 105: front wheel, 106: rear wheel, CA: cylinder axis, HC1: first hydraulic chamber (high pressure chamber), HC2: second hydraulic chamber (low pressure chamber), S1: space, P1: first intersection portion, P2: second intersection portion, P3: portion of base end of inner sleeve that overlaps with first groove in plan view, HP: uppermost point of base end of inner sleeve, LP: lowermost point of base end of inner sleeve

Claims

1. A hydraulic tensioner that applies tension to an endless transmission member wrapped around a crankshaft and a camshaft of an internal combustion engine, a tensioner body having a through hole; a plunger having a bottom and a cylindrical shape, the plunger being inserted into the through hole of the tensioner body so as to be movable in an axial direction of the through hole; A cylindrical inner sleeve inserted inside the plunger; a tensioner cap attached to one end of the tensioner body, the tensioner cap having a first surface that contacts a base end of the inner sleeve; Equipped with a first hydraulic chamber is formed between the inner sleeve and the plunger, and a second hydraulic chamber for storing oil to be supplied to the first hydraulic chamber is formed inside the inner sleeve, a first surface of the tensioner cap having a plurality of grooves each of which connects a radial outside of the inner sleeve with the second hydraulic chamber.

2. the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, Among the plurality of grooves, a groove that is located at the lowest position when the internal combustion engine is operating is referred to as a first groove, a portion on the first surface where the oil supply passage intersects with a projection of an outer circumferential edge of the plunger onto the first surface is called a first intersecting portion, When a portion on the first surface where a groove among the plurality of grooves other than the first groove intersects with a projection of the outer circumferential edge of the plunger onto the first surface is referred to as a second intersecting portion, 2. The hydraulic tensioner according to claim 1, wherein a portion of a base end of the inner sleeve that overlaps with the first groove in a plan view from the axial direction is located lower than the first intersecting portion and the second intersecting portion when the internal combustion engine is operating.

3. the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, Among the plurality of grooves, a groove that is located at the lowest position when the internal combustion engine is operating is referred to as a first groove, a portion on the first surface where the oil supply passage intersects with a projection of an outer circumferential edge of the plunger onto the first surface is called a first intersecting portion, When a portion on the first surface where a groove among the plurality of grooves other than the first groove intersects with a projection of the outer circumferential edge of the plunger onto the first surface is referred to as a second intersecting portion, 3. The hydraulic tensioner according to claim 1, wherein the second intersecting portion is located at a higher position than the first intersecting portion when the internal combustion engine is in operation.

4. 3. The hydraulic tensioner according to claim 1, wherein at least one of the plurality of grooves overlaps, in a plan view seen from the axial direction, an uppermost point of the base end of the inner sleeve when the internal combustion engine is operating.

5. 3. The hydraulic tensioner according to claim 1, wherein at least one of the plurality of grooves overlaps, in a plan view seen in the axial direction, with a lowest point of the base end of the inner sleeve when the internal combustion engine is in operation.

6. a biasing member disposed inside the first hydraulic chamber and biasing the plunger toward the endless transmission member; a check valve unit disposed between the first hydraulic chamber and the second hydraulic chamber; 3. The hydraulic tensioner of claim 1 or 2, further comprising:

7. the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, 3. The hydraulic tensioner according to claim 1, wherein the oil supply passage and the plurality of grooves are continuous with each other.

8. the first surface of the tensioner cap has a groove-shaped oil supply passage extending from outside to inside of an outer circumferential edge of the plunger in a plan view seen in the axial direction, 3. The hydraulic tensioner of claim 1, wherein the oil supply passage and the plurality of grooves are separated from each other.

9. 3. The hydraulic tensioner of claim 1 or 2, wherein the plurality of grooves includes two grooves that are contiguous with one another.

10. 3. The hydraulic tensioner of claim 1 or 2, wherein the plurality of grooves includes two grooves that are separated from one another.

11. 3. An internal combustion engine comprising the hydraulic tensioner according to claim 1 or 2.

12. A saddle-type vehicle comprising the internal combustion engine according to claim 11.

Images