JPH03153945A - Chain tensioner - Google Patents

Abstract

PURPOSE:To provide possibility of complying with quick changes of a cam chain by interposing a plate-shaped spring member between a tensioner body and a hydraulic adjuster. CONSTITUTION:A tensioner body 15 to press the slack side of a cam chain 12 is borne rotatably at a cylinder head 1b by a pivot 18 provided at the fixed end 15a. A lever 17 consisting of a leaf-form spring member is fitted on the pivot 18 capable of rotating independently rotatably and is interposed between the tensioner body 15 and hydraulic adjuster 16, wherein the free end is in contact with the tensioner body 15. When vibration is generated abruptly in the cam chain 12, the movement is transmitted directly to the tensioner body 15 to be however absorbed with elastic deformation of the lever 17, and the resilient action there generates pressing to the cam chain 12. This enhances followup characteristic of the body 1 after motion of the chain 12, which is thus given a tension of constant load.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chain tensioner used primarily as a means for maintaining a constant tension in a cam chain in an internal combustion engine.

[Prior Art] - In an internal combustion engine, a drive sprocket for driving a cam chain is fixed to the crankshaft so as to rotate integrally with the drive sprocket, and the rotation of the drive sprocket is controlled via the cam chain and the driven sprocket. The power is transmitted to a camshaft located inside the cylinder head.

The cam chain is equipped with a cam chain tensioner to suppress the waviness that occurs when the cam chain moves at high speeds, and to compensate for slack in the chain itself to maintain a constant tension.

For example, the technology of this cam chain tensioner is disclosed in Japanese Utility Model Application Laid-open No. 60-86665.

This is because the tensioner, which is placed on the outside of the cam chain on the slack side and is loosely curved in an arch shape and arranged along the cam chain, has a fixed end with a rotating shaft on the driven sprocket side, and a free end on the other end. The end of the tensioner is rotatably supported, and the tensioner is applied to the cam chain by pressing the back of the central part of the tensioner via the rocker arm with a rod that is biased by a spring and set so as not to be retractable. It has become.

[Problems to be Solved by the Invention] By the way, in such a cam chain tensioner, if the cam chain suddenly flutters or vibrates due to, for example, fluctuations in the angular velocity of both sprockets, the rod may retreat. If the rod advances in response to a large movement of the cam chain, the tension on the cam chain and the load on the tensioner on the cam chain will increase, causing the cam chain to elongate. There are issues such as storage. Further, although an elastic member such as rubber or resin may be interposed between the rod and the tensioner, there is a problem that it is difficult to obtain a stable set load and a sufficient tension stroke.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and includes a tensioner body that is placed on the outside of a chain that extends between a driving sprocket and a driven sprocket. In the chain tensioner, the tensioner body and the chain tensioner are arranged so as to be in contact with each other and apply a predetermined tension to the chain by pressing the tensioner body against the chain by a hydraulic adjuster attached to a fixed member. A plate-shaped or dish-shaped spring member having a stable set load and a sufficient spring stroke is interposed between the hydraulic adjuster and at least one of the fixed member and the hydraulic adjuster. There is.

[Function] According to the chain tensioner of the present invention, when sudden fluctuations in the cam chain are transmitted to the tensioner body due to fluctuations in the angular velocity of the driving sprocket and the driven sprocket, for example, the plate-shaped or dish-shaped spring member absorbs and The elastic force improves the ability of the tensioner body to follow changes in the cam chain, and a constant load of tension is always applied to the cam chain, thereby suppressing elongation of the cam chain.

[Example] Hereinafter, each example of the present invention will be described with reference to the drawings. Note that the same constituent elements in each drawing will be explained in the first embodiment, and will be omitted in the following embodiments.

First Embodiment: FIG. 1(a)(0) FIG. 1 shows a cross-sectional view of a main part of an internal combustion engine to which the chain tensioner of the present invention is applied.

This internal combustion engine is a so-called DOHC type in which two camshafts are arranged above the combustion chamber (as shown), and the reference numeral l in the figure represents cylinder block la, cylinder head lb, and cylinder head force/<-1c. The cylinder 2 is an upper side 2a and a lower side 2 fixed to the cylinder block la.
3 is an oil pan fixed to the crankcase 2, 4 is housed in the crankcase 2, and the lubricating oil accumulated in the oil pan 3 is transferred to the cylinder block l.
An oil pump that pumps oil into the inside of a or the valve mechanism (as shown), etc.
5 is the lubricating oil filter, 6 is a transmission mechanism, and 7 is a starter motor.

A crankshaft 8 connected to a piston (not shown) is rotatably supported inside the crankcase 2, and a drive sprocket 9 for driving a cam chain is mounted coaxially with the crankshaft 8. and are fixed so that they rotate together.

Two camshafts IO each having a cam 10a for driving a valve mechanism are rotatably provided in the cylinder head 1b parallel to the crankshaft 8 at a distance from each other. A driven sprocket 11 is fixed to the shaft 10 so as to rotate coaxially and integrally with the camshaft 10.

A cam chain 12 is spanned between the drive sprocket 9 on the crankshaft 8 side and the two driven sprockets 11 and 11 on the camshaft lO side, whereby the rotation of the crankshaft 8 is directed from the drive sprocket 9 to the cam chain. 12 and driven sprocket 11
-11 to each camshaft 10, 10,
The valve mechanism is driven to open and close.

Drive sprockets 9 and 2 in cam chain 12
On one side (left side in the figure) between the two driven sprockets 11-11, there is a chain guide 13 that reliably guides the passage of the cam chain 12 in this part.
2, the cylinder block la,
It is provided integrally with the cylinder head TBS and the inner surface of the crankcase 2.

Further, a cam chain tensioner 14 according to the present invention is provided on the slack side of the cam chain 12, which is the side opposite to the blade side, on the outer right side in the figure.

This cam chain tensioner 14 is connected to the cam chain 12.
A tensioner main body 15 that is brought into contact with the outer peripheral surface of the tensioner main body 15, a hydraulic adjuster 16 that presses the tensioner main body 15 against the cam chain 12, and a spring member interposed between the tensioner main body 15 and the hydraulic adjuster 16. It is composed of a lever 17.

The tensioner main body 15 is a member that is made of a material having a predetermined elasticity and is formed into an elongated plate shape, and can be bent into an arcuate shape due to its elasticity. Then, a fixed end 1 is placed near the driven sprocket 11.
5a, and a pivot 18 with a free end 15b disposed towards the drive sprocket 9 and provided on the fixed end 15a.
It is rotatably supported by the cylinder rad 1b.

Further, the lever 17 is attached to the pivot 1B so as to be rotatable independently of the tensioner body 15. The lever 17 is made of a plate spring material such as metal or resin having a predetermined elasticity, and is formed into an elongated and straight plate shape in a free state, and its length is set to about 273 of the length of the tensioner body 13. The fixed end 15a is supported by a pivot 18 and is rotatable, and the free end 15b has a circular cross section and is brought into contact with the back surface of the tensioner body 15.

Further, the hydraulic adjuster 16 is provided on the back side of the intermediate portion of the lever 17.

As shown in FIG. 2, this hydraulic adjuster 16 has a plunger insertion hole 19a, a reservoir chamber 19b communicating with the plunger insertion hole 19a, and an oil passage 19C communicating the reservoir chamber 19b with the outside. The plunger body 19 is fixed through the cylinder block (fixed member) la with the plunger insertion hole 19a facing above /<-15, and the plunger insertion hole 19al of this plunger body 19 is slidable. A plunger 20 is inserted, has a spherical tip, and has an oil chamber 20a inside, and is fitted into the oil chamber 20a of the plunger 20 and removed from the plunger insertion hole 19a of the plunger body 19. An adjustment spring 21 biasing the plunger body 19 in the direction shown in FIG. A pole cage 23 is provided with an oil hole 23a formed therein, and a check pole spring 2 is housed in the pole cage 23.
and a check pole 25 that is biased by the valve 4 and closes the opening of the sleeve 22 toward the oil chamber 20a.

In this hydraulic adjuster 16, the plunger 20 is perpendicular to the lever 17 and its tip abuts against the back surface of the lever 17 in a state fixed to the cylinder block la, and the oil pressure adjuster 16 is connected to the reservoir chamber 1 through the oil passage 19c of the plunger body 19.・9b
The oil chamber 20a is filled with hydraulic oil, and the plunger 20 supported by the oil pressure of the hydraulic oil and the last month of the adjustment spring 21 presses the lever 17.

The operation of the cam chain tensioner 14 as a whole together with the hydraulic adjuster 16 will be explained in detail. The plunger 20 biased by the adjustment spring 21 presses the lever 17, and the amount of hydraulic oil in the reservoir chamber 19b that is pushed out by the plunger 20 is released into the sleeve. The check pole 25 is pushed through the communication path 22a of the pole cage 23, and flows into the oil chamber 20a through the oil hole 23a of the pole cage 23. When the plunger 20 stops protruding, the check pawl 25 is biased by the check pawl spring 24 and closes the opening of the sleeve 22, preventing the hydraulic oil in the oil chamber 20a from flowing back into the reservoir chamber 19b. The protruding position is maintained.

The lever 17 pressed by the plunger 20 is deformed into a curve due to its elasticity, and the tip that contacts the back surface of the tensioner body 15 moves the tensioner body 15 into the cam chain 1.
Press against 2. With this, the cam chain 12
A constant tension is applied to the

According to such a cam chain tensioner 14, I;
For example, if the cam chain 12 suddenly flutters or vibrates due to fluctuations in the angular velocity of the crankshaft 8 and camshaft 10, that is, fluctuations in the angular velocity of the driving sprocket 9 and driven sprocket 11, the movement will be The movement of the tensioner body 15 is directly transmitted to the tensioner body 15, but this movement of the tensioner body 15 is absorbed by the elastic deformation of the lever 17, and the tensioner body 15 is absorbed by the elastic deformation of the lever 17.
is pressed against the cam chain 12. The ability of the tensioner main body 15 to follow the movement of the cam chain 12 is improved by the lever 17 for absorption and repulsion, and a constant load of tension is applied to the cam chain 12.

Further, by applying a constant load of tension to the cam chain 12 in this manner, elongation of the cam chain 12 and progress of wear of the tensioner body 15 are suppressed, and the durability of both is improved.

Second Embodiment: Fig. 2 Reference numeral 30 in Fig. 2 indicates a cam chain tensioner of the second embodiment, and this cam chain tensioner 3° includes the tensioner main body 15 and hydraulic adjuster 16 of the first embodiment, and these parts. A lever 31 as a spring member interposed between
It is composed of.

/<-31 is made of a plate spring material such as metal or resin having a predetermined elasticity and is formed into an elongated and straight plate shape in a free state, and its length is longer than that of the lever 17 of the first embodiment. It is set slightly shorter and its fixed end 3
1a is rotatably supported by a pivot 32 provided below the pivot 18 that supports the tensioner main body 15, and its free end 31b is formed with a circular cross section. It is brought into contact with the back of 5.

Then, the tip of the plunger 20 in the hydraulic adjuster 16 is brought into contact with the back surface of this lever 31, as in the first embodiment, and this hydraulic adjuster 16 allows
1, the tensioner main body 15 is pressed against the cam chain 12.

Third Embodiment: Figure 3 Numeral 40 in Figure 3 indicates a cam chain tensioner of the third embodiment, and this cam chain tensioner 4° consists of a tensioner body 41, a hydraulic adjuster 16 similar to the above embodiment, and a lever 42 as a spring member interposed between
It is composed of.

The tensioner main body 41 is made of a material having a predetermined elasticity and is formed into an elongated plate shape, and is a member that can be bent into a bow shape due to the elasticity, and has a fixed end 41a near the drive sprocket 9 and a free end 41b near the driven sprocket ll. It is rotatably supported on the upper side 2a of the crankcase 2 by a pivot 43 provided at a fixed end 41a.

Further, the lever 42 is attached to the pivot 43 with its tip (free end) facing the driven sprocket 11 so that it can rotate independently of the tensioner body 41. This lever 42 is made of a plate spring material such as metal or resin having a predetermined elasticity, and is formed into a long and thin straight plate shape in a free state, and its length is set slightly shorter than the tensioner body 41, and has a circular cross section. The formed tip is brought into contact with the back surface of the tensioner main body 41.

Further, the hydraulic adjuster 16 is arranged on the back side of the lever 42 by having its plunger body 19 penetrate through the crankcase 2 and fixed, and the plunger 2
0 is perpendicular to the lever 42, and its tip is brought into contact with the back surface of the lever 42. As in the first and second embodiments, the tensioner body 41 is moved to the cam chain 1 by the hydraulic adjuster 16 via the lever 42.
It is pressed against 2.

Note that in this embodiment, the cam chain tensioner 40
A sub-chain guide 45 is disposed on the front end side of the tensioner body 42, which is rotatably supported by a pivot 44 provided on the cylinder head lb, and which comes into contact with the outer peripheral surface of the cam chain 12' and guides the passage of the cam chain 12. ing.

According to the cam chain tensioners 30 and 40 of the second and third embodiments described above, the levers 31 and 42 provided therein function in the same manner as the lever 17 of the first embodiment, and as a result, the cam chain A constant load of tension is applied to the tensioner body 15 to suppress the elongation of the cam chain 12 and the progress of wear of the tensioner body 15, thereby improving the durability 4f of both.

Fourth Embodiment: FIG. 4 Reference numeral 50 in FIG. 4 indicates a cam chain tensioner of the fourth embodiment. A lever (spring member) 51 that is independently rotatably supported and has its front surface abutted against the back surface of the tensioner main body 15; a disc spring (spring member) 52 provided on the back surface of the lever 51; The hydraulic adjuster 16 acts on the disc spring 52.

The lever 51 is formed into a rectangular plate shape from a leaf spring material having a predetermined elasticity, and is slightly shorter than the main body 15 that covers the tension, and is formed to become thinner toward the free end that is the tip. A spring seat 53 having a recess 53a is fixed to a substantially central portion of the back surface of the lever 51, and within the recess 53a of the spring seat 53, the disc spring 52 is mounted with its convex surface facing the hydraulic adjuster 1G. It is stored.

The hydraulic adjuster 16 is fixed to the cylinder block la at the same position as in the first and second embodiments, facing the disc spring 52. In this fixed state, the tip of the plunger 20 is in contact with the convex surface of the disc spring 52.

In addition, the tip surface of the plunger 20 in this case is connected to the disc spring 5.
It is formed flat so that the convex surface of No. 2 follows.

According to the cam chain tensioner 50 having such a configuration, the hydraulic adjuster 16 moves the tensioner main body 15 to the cam chain 1 via the lever 51 and the disc spring 52.
It is pressed against 2.

Therefore, when the tension body 15 rotates due to fluttering, vibration, etc. of the cam chain 12, the movement is absorbed by the lever 51 and the disc spring 52.
The main body 15, which is tensed by the elastic force, is pressed against the cam chain 12.

The tensioner main body 15 is connected to the cam chain 12 by the lever 51 and the disc spring 52 for two-stage absorption and rebound action.
A constant load of tension is always applied to the cam chain 12 following the movement of the cam chain.

Fifth embodiment y4 = Figure 5 Reference numeral 60 in Figure 5 indicates a cam chain tensioner of the fifth embodiment. A lever (spring member) 61 is rotatably supported by the tensioner main body 15 and its front surface is brought into contact with the back surface of the tensioner body 15, and a holder (spring member) provided on the back surface of the lever 61.
The hydraulic adjuster 63 is slidably inserted into a fixed member (fixed member) 62, and a disc spring 64 having a predetermined elasticity is disposed on the bottom side of the hydraulic adjuster 63 to support the hydraulic adjuster 63. ing.

The lever 61 is substantially the same as the lever 51 of the fourth embodiment, except that a pressing force 9461a that protrudes toward the hydraulic adjuster 63 is formed approximately at the center of the rear surface of the lever 61.

The hydraulic adjuster 63 is substantially the same as the hydraulic adjuster 16 of the first to fourth embodiments, but the plunger body 65 into which the plunger 20 is inserted is simply formed into a cylindrical shape with a circular cross section. The plunger body 65 is slidably inserted into the holder 62, and the holder 62 is fixed to the cylinder block la. In this fixed state,
The tip of the plunger 20 is in contact with the surface of a pressing portion 61a formed on the lever 61.

Here, the disc spring 64 is disposed between the bottom of the holder 62 and the bottom of the plunger body 65 via a spacer 66.
The cam chain tensioner 60 is stored with its convex surface facing toward the plunger body 65 and in contact with the bottom surface of the plunger body 65. According to the cam chain tensioner 60 having such a configuration, the hydraulic adjuster 63 is moved through the lever 61. The tensioner main body 15 is pressed against the cam chain 12, and the disc spring 64 receives the reaction force, and tension is applied to the cam chain 12 while the balance is maintained.

When the tension main body 15 rotates due to fluttering, vibration, etc. of the cam chain 12, the movement is caused by the elastic deformation of the lever 61 and the hydraulic adjuster 63 that retreats into the holder 62 against the disc spring 64. The tensioner main body 15 is pressed against the cam chain 12 by the spring action of the lever 61 and the disc spring 64.

The tensioner main body 15 is connected to the cam chain 12 by the lever 61 and the disc spring 64 for the two-stage absorption/repulsion action.
A constant load of tension is always applied to the cam chain 12 following the movement of the cam chain.

In the fourth and fifth embodiments described above, each lever 51.
61 and each disc spring 52, 64 to tighten the tensioner body 15.
The followability of the cam chain 12 to the cam chain 12 is good, and as a result, a constant load of tension is always applied to the cam chain 12, which prevents the elongation of the cam chain 12 and the tensioner body 15.
The progress of wear is suppressed and the durability of both is improved.

In addition, although each of the above embodiments shows an example in which the present invention is applied to a cam chain in an internal combustion engine, the present invention is not limited to such a cam chain, but can be applied to various chains that require a constant tension. is possible.

[Effects of the Invention] According to the chain tensioner of the present invention, the tensioner body is disposed on the outside of the chain extending between the driving sprocket and the driven sprocket so as to come into contact with the outer peripheral surface of the chain, and the tensioner body is In the chain tensioner, a hydraulic adjuster attached to a fixed member applies pressure to the chain to apply a predetermined tension to the chain. The tensioner body is characterized by a plate-shaped or disc-shaped spring member interposed at least on one side between the tensioner and the hydraulic adjuster, and the spring member's absorption and elastic force prevents the tensioner body from responding to sudden fluctuations in the cam chain. Following this, a constant load of tension is always applied to the cam chain, and as a result, the elongation of the cam chain is suppressed.

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing a first embodiment of an internal combustion engine to which the cam chain tension of the present invention is applied;
B) is a sectional view of the hydraulic adjuster, FIG. 2 is a sectional view of the second embodiment, FIG. 3 is a sectional view of the third embodiment, FIG. 4 is a sectional view of the fourth embodiment, and FIG. 5 is a sectional view of the fourth embodiment. FIG. 5 is a cross-sectional view of Example 5. la...Cylinder block (fixed member), 9.
... Drive sprocket, 11 ... Driven sprocket, 12 ... Cam chain, 14.3
0,40,50160...Cam chain tensioner, 15...Tensioner body, 16.63.
...Hydraulic adjuster, 17.31.42.51,
61...Lever (spring member), 52.64...
... disc spring (spring member), 62 ... holder (fixing member).

Claims (1)

[Claims] A tensioner body is disposed on the outside of the chain that extends between the driving sprocket and the driven sprocket so as to come into contact with the outer peripheral surface of the chain, and the tensioner body is pressed against the chain by a hydraulic adjuster attached to a fixed member. In this chain tensioner, a plate-shaped or plate-like member is provided between the tensioner main body and the hydraulic adjuster, and between the fixing member and the hydraulic adjuster. A chain tensioner characterized by having a shaped spring member interposed therebetween.