JPH03234954A - Chain tensioner for internal combustion engine - Google Patents

Abstract

PURPOSE:To make an internal combustion engine more compact by providing the circumferential surface of a support shaft with a lubricant passage introducing lubricant out of a lubricant passage within an engine main body, and thereby disposing an abutting section which comes in contact with a pad section and the tip end of an adjuster rod, roughly just under the support shaft. CONSTITUTION:In a lubricating mechanism for a chain tensioner 15, a lubricating passage 25 is provided so as to be recessed at the center section of a support shaft 16, the passage 25 is communicated with a lubricant passage 28 within a head 3 through a mounting hole 26 on the cylinder head 3 side and a communication hole 27, and is also communicated with a communication hole 29 which penetrates a shaft 16 in a cruciform shape. This thereby permits lubricant pressurized by an oil pump to be supplied on the outer surface of the shaft 16 through the passage 25 and the like for lubricating a space between a bush 22 and the shaft so as to be collected into an oil arresting groove 31, the lubricant is then concurrently dropped down out of an oil discharging port 32 so that the lubricant thereby lubricates an abutting section which comes in contact with the tip end of an adjuster rod 21 and a pad section 20 at all times. There is thereby no need for a lubricant passage exclusively used for the tip end of the rod 21 and the pad section 20.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a chain tensioner for applying appropriate tension to a cam chain in a camshaft drive device for an internal combustion engine using a cam chain, particularly an improvement in its lubrication mechanism. Regarding.

Conventional technology For example, in an OHC type valve train in which the camshaft is placed in two parts of the cylinder head, a cam chain system is used in which a cam chain is wound between the cam sprocket at the front end of the camshaft and the crank sprocket at the front end of the crankshaft. camshaft drive devices are often used.

In this type of camshaft drive device, a chain tensioner is provided between the cam sprocket and the crank sprocket to apply tension to the chain.

This chain tensioner is of the type that directly presses the chain inward using a sliding member at the tip of the rod that is urged in the protruding direction by hydraulic pressure or the like (for example, Japanese Utility Model Application Publication No. 107143/1983). However, in this type of chain, the chain is in constant sliding contact with the sliding member, which increases friction loss during high-speed operation and is also disadvantageous in terms of noise.

Therefore, a chain tensioner is known in which a tensioner sprocket meshed with a cam chain is rotatably provided and the tensioner sprocket is pressed toward the inner circumference of the cam chain (for example, in
(See Publication No. 159, etc.).

In this type of chain tensioner, a support shaft is installed on the front end face of the engine body, that is, the cylinder head or cylinder block, and the tensioner bracket is rotatably supported here, and the tensioner sprocket rotates at the tip of the tensioner bracket. It can be installed freely. Then, by pressing the side of the tensioner bracket with a protruding adjuster rod using hydraulic pressure, etc., the tensioner bracket rotates and presses the cam chain inward via the tensioner sprocket. .

Problems to be Solved by the Invention However, in the sprocket type chain tensioner as described in 1., the bearing part between the support shaft and the tensioner bracket, and the contact part between the tip of the adjuster rod and the tensioner bracket side pad part. Each requires lubrication. In order to ensure this lubrication, it is necessary to provide a dedicated lubricating oil passage from inside the cylinder head, etc., and force lubrication, but in particular, the contact area between the adjuster rod tip and the tensioner bracket side pad. On the other hand, providing a dedicated lubricating oil passage not only complicates the configuration, but also restricts the degree of freedom in designing the cylinder head, etc., and poses a major obstacle in making the internal combustion engine more compact.

Means for Solving the Problems Therefore, the present invention performs forced lubrication only on the bearing portion between the support shaft and the tensioner bracket, and uses the lubricant dripping from the bearing portion to prevent the contact portion between the tip of the adjuster rod and the pad portion on the tensioner bracket side. It is designed to provide lubrication. That is, the present invention includes a tensioner bracket rotatably supported by a support shaft installed on the front end surface of an engine body, and a tensioner sprocket rotatably attached to the tip of the tensioner bracket and meshing with a cam chain. 1) The pad part provided on the side of the tensioner bracket and the tip of the adjuster rod fixed to the front end surface of the engine body and biased in the projecting direction come into pressure contact with the pad part, causing the tensioner bracket to move. In a chain tensioner for an internal combustion engine, which is equipped with an adjuster that presses in the rotational direction, a lubricating oil passage is provided on the outer circumferential surface of the support shaft for guiding lubricating oil from a lubricating oil path inside the engine body, and a pad portion described in -1- is provided. and the tip of the adjuster rod are placed almost directly under the biped support shaft,
It is characterized in that it is configured so that lubricating oil drips from the support shaft portion.

The bearing between the support shaft and the tensioner bracket is
Lubricating oil is pumped from a lubricating oil path inside the engine body through a lubricating oil passage. This lubricating oil further flows out from the support shaft portion, drips downward, and is guided to the contact portion between the pad portion on the side of the tensioner bracket and the tip of the adjuster rod.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on FIGS. 1 to 4.

This embodiment is applied to a camshaft drive device for a V-type internal combustion engine, and as shown in FIG. are fixed, an intake camshaft 4, 5 and an exhaust camshaft 6.7 are arranged in each cylinder head 2.3, and a crankshaft 8 is arranged at the lower part of the cylinder block 1. Further, a cam sprocket 9.10 is attached to the front end of each exhaust side camshaft 6.7, a crank sprocket II is attached to the front end of the crankshaft 8, and a crank sprocket II is attached to the front end of the crankshaft 8. A water pump sprocket I2 is arranged.

A cam chain I3 is disposed on the front end surface of the engine body consisting of the cylinder block 1 and the cylinder head 2.3. For details, see 9. Left and right cam sprockets. l
One cam chain 13 is wound around four parts: O, the central crank sprocket 11, and the water pump sprocket 12. The cam sprocket 9.degree. 10 and the crank sprocket 11 are engaged with the inner circumferential side of the cam chain 13, whereas the water pump sprocket 12 is engaged with the outer circumferential side of the cam chain 13.

That is, in this embodiment, one cam chain 13 drives both the left and right bank valve gears and the water pump at the same time. Incidentally, the intake side camshafts 4 and 5 are interlocked with the exhaust side camshaft by a suitable gear mechanism or chain mechanism.

Further, an idle sprocket 14 serving as a simple idler is provided at the front end of the cylinder head 2 of one bank, and engages with the cam chain 13 from the outer circumferential side.

Further, a chain tensioner 15 is disposed at the front end of the cylinder head 3 of the other bank so as to be substantially symmetrical with the idle sprocket 14.

As shown in detail in FIG. 1, this chain tensioner 15 has a support shaft I6 installed on the front end surface of the cylinder head 3.
, a lever-shaped tensioner bracket 17 rotatably supported by the support shaft 16 , a tensioner sprocket 8 rotatably attached to the tip of the tensioner bracket 17 and meshing with the cam chain 13 from the outer circumferential side. , and an adjuster I9 that is fixed to the front end surface of the cylinder head 3 and biases the tensioner bracket 17 in one direction using hydraulic pressure or spring force, and applies internal pressure to the cam chain 13 to apply appropriate tension. There is.

The tensioner bracket 17 has a branch section 17a on its lower side, and a pad section 20 having an arcuate contact surface is provided at the tip thereof.

The tip of the adjuster rod 21 protruding in the axial direction of the adjuster 19 comes into pressure contact with the pad portion 20, and presses the tensioner bracket 17 in the rotational direction.

Further, as shown in FIG. 3, the tensioner bracket 17 is made of metal plates provided to sandwich the tensioner sprocket 18 from both sides, and a cylindrical bushing 22 is welded at the bearing portion that fits into the support shaft 16. has been done. This bushing 22 together with the washer 23 supports the support shaft I6.
It is inserted into the holder and is prevented from being removed by a snap ring 24.

On the other hand, as a lubrication mechanism in this chain tensioner 15, a lubricating oil passage 25 is recessed in the center of the support shaft 16. It communicates with the lubricating oil passage 28 inside the head 3, and also communicates with the support shaft 16.
It communicates with a communication hole 29 (see FIG. 4) that extends through the cross section.

Therefore, lubricating oil pressurized by an oil pump (not shown) is supplied to the outer peripheral surface of the support shaft 16 through the lubricating oil passage 25 and the like, and the space between it and the bushing 22 is lubricated.

Further, a support shaft I is provided on the lower side of the inner peripheral surface of the bush 22.
6. An oil collection groove 31 is partially recessed so as to collect the lubricating oil flowing out onto the outer peripheral surface, and the oil collection groove 3
An oil discharge hole 32 is formed through the oil discharge hole 32 so as to communicate with the oil discharge hole 1 (see FIG. 4).

The contact portion between the adjuster rod 21 and the pad portion 207 described above is located approximately directly below the support shaft 6, more specifically, approximately directly below the discharge hole 32. Note that the line ■-■ in FIG. 1 is along the vertical direction in the actual vehicle-mounted state.

Therefore, in the -1-2 configuration, the lubricating oil used to lubricate the support shaft 16 is collected in the oil collection groove 31 and drips downward from the oil discharge hole 32, and this is transferred to the tip of the adjuster rod 21 and the pad portion 20. Always lubricate the contact parts. That is, reliable lubrication can be performed without forming a lubricating oil passage inside the cylinder head 3 or the like.

Next, FIGS. 5 to 7 show different embodiments of this invention.

In this embodiment, oil collection grooves 41 and oil discharge grooves 42 are recessed in the outer surfaces of the flanges 17b and 17c of the tensioner bracket 17 that supports both ends of the bushing 22. is provided in an arc shape so as to cover substantially the lower half of the bushing 22, and the oil drain groove 42 is connected to the lowest point thereof. This oil drain groove 42 also points toward the contact portion between the tip of the adjuster rod 21 and the pad portion 20.

In order to more reliably guide the lubricating oil to the oil collecting groove 41, notches 43 are provided at both ends of the bushing 22, not shown in FIG. ing.

Therefore, the lubricating oil used to lubricate the support shaft I6 and the bushing 22 is transmitted from both ends of the bushing 22 to the contact area between the tip of the adjuster rod 2I and the pad portion 20 via the oil collection groove 41 and the oil drain groove 42. You will definitely be guided.

The bearing portion of the tensioner sprocket I8 may be lubricated by oil mist in the chain chamber or oil droplets guided through a protrusion provided on a chain cover (not shown).

As is clear from the explanation in Section 2 of ``Effects of the Invention'', in the engine tensioner for an internal combustion engine according to the present invention, the lubricating oil used for lubrication between the support shaft and the tensioner bracket drips downward and the adjuster. It is possible to reliably lubricate the space between the rod tip and the pad on the tension bracket side. Therefore, there is no need to provide a dedicated lubricating oil passage for the contact portion between the tip end of the adjuster rod and the pad portion, and the degree of freedom in designing the cylinder head and the like is increased, and the design can be made more compact.

[Brief explanation of drawings]

FIG. 1 is a front view of the main parts of an internal combustion engine showing an embodiment of the chain tensioner according to the present invention, FIG. 2 is a front view of the entire internal combustion engine, and FIG. cross-sectional view,
FIG. 4 is a cross-sectional view of the main part along line [-1V1 2 in FIG. 3, FIG. 5 is a front view showing a different embodiment of the present invention, and FIG. 6 is a cross-sectional view along line FIG. 7 is a perspective view of the bushing. 15... chain tensioner, 16... support shaft, 1
7... Tensioner bracket, 18... Tensioner sprocket, 19... Adjuster, 20... Pad portion, 25... Lubricating oil passage, 29... Communication hole, 32
...Oil drain hole.

Claims (1)

[Claims] (1) A tensioner bracket rotatably supported by a support shaft installed on the front end surface of the engine body, a tensioner sprocket rotatably attached to the tip of the tensioner bracket and meshing with the cam chain, and the tensioner sprocket mentioned above. The pad section provided on the side of the bracket and the tip of the adjuster rod fixed to the front end surface of the engine body and biased in the protruding direction come into pressure contact with the pad section and press the tensioner bracket in the rotation direction. A chain tensioner for an internal combustion engine is provided with a lubricating oil passage on the outer circumferential surface of the support shaft for guiding lubricating oil from a lubricating oil path inside the engine body, and the pad portion and the tip of the adjuster rod are brought into contact with each other. A chain tensioner for an internal combustion engine, characterized in that a portion is disposed almost directly below the support shaft so that lubricating oil drips from the support shaft portion.