JPH0311361Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an adjustment mechanism for a hydraulic lash adjuster in a valve train for an internal combustion engine.

Prior Art FIG. 1 shows an example of a valve train using a hydraulic lash adjuster. 01 is a cylinder head of a motorcycle four-cycle gasoline engine that is inclined along the front and rear surfaces, and cylinder head 0
1 is formed with an intake port 02 and an exhaust port 03, and an intake valve 04 and an exhaust valve 05 are provided so that the intake and exhaust ports 02 and 03 can be opened and closed, respectively.

Additionally, the camshaft 0 located between the intake and exhaust valves 04 and 05 is connected to a camshaft holder 06 (only a portion is shown).
and the cylinder head 01, and the camshaft 0
A pair of Rocker arm shafts 09 located above 7
is supported by a camshaft holder 06.

The rocker arm shaft 09, which is rotatably supported by the camshaft holder 06 at the large-diameter journal 09A, is equipped with a small-diameter eccentric shaft 09B that is eccentric from the center of rotation by a certain amount.
A rocker arm 08 is tiltably supported by 9B. A groove-like notch 09a with a depth extending from the outer periphery to the center of rotation is formed in the journal 09A, and a hydraulic lash adjuster 010 that comes into contact with the groove bottom of this notch 09a connects the cylinder head 01 and the cam. It is fitted into and held in the opening of the shaft holder 06.

Further, a small notch 09b is formed in the journal 09A from the outer periphery on the opposite side from the notch 09a, and the auxiliary shaft 011 is slidably fitted and held in the opening formed in the camshaft holder 06. , is biased by the elastic force of the auxiliary spring 012, comes into contact with the small notch 09b, and the hydraulic latch adjuster 0
Together with 10, it applies a force to rotate the rocker arm shaft 09 in the direction of arrow A.

The hydraulic latch adjuster 010 and the auxiliary shaft 011 have a notch 09a and a small notch 09 while the intake/exhaust valves 04 and 05 are in the closed position.
The rocker arm shaft 09 is rotated in the direction of the arrow A in contact with
It acts to press against the stem ends 04a, 05a of 05, thereby eliminating tappet clearance, and also prevents rotation of the eccentric shaft 09B when the valve is opened.

In this way, the hydraulic lash adjuster 010
By using a valve mechanism, the tappet clearance can be maintained at zero regardless of whether it is cold or warm, so there is no noise, there is no need to adjust the tappet clearance, and there is no shock to the valve mechanism, reducing wear. There are advantages such as less

Problems to be Solved However, in the above-mentioned valve train mechanism, it is necessary to cover all of the following machining tolerances (or machining errors) with the adjustment function (i.e., plunger stroke) of the hydraulic lash adjuster 010. - In order to ensure sufficient stroke, the capacity of the hydraulic lash adjuster 010 had to be increased.

Notch 09a in Rocker arm shaft 09
machining tolerance (or machining error).

In the rocker arm 08, the tolerance in the positional relationship between the sliding surface with the cam 07A and the contact surface with the stem end 05a.

Processing tolerance (or processing error) of the opening for supporting the rocker arm shaft 09 in the camshaft holder 06.

Processing tolerance (or processing error) of the bottom surface of the body of the hydraulic latch adjuster 010 and the opening provided in the camshaft holder 06 to hold the latch adjuster 010.

In order to absorb such processing tolerances, there was an adjustment mechanism described in Japanese Utility Model Application Publication No. 57-66206.

In this adjustment mechanism, the lash adjuster is inserted into the lash adjuster insertion hole formed at the tip of the rocker arm, and the insertion depth is adjusted by the adjustment screw screwed onto the top of the tip of the rocker arm. I was getting used to it.

However, in the above adjustment mechanism, the lash adjuster is also inserted into the lash adjuster insertion hole at the tip of the rocker arm from the stem side of the intake/exhaust valve, so it is difficult to inspect or replace the lash adjuster. When carrying out maintenance, do not remove the Rodscar arm from the Rodscar shaft.
Inspection work becomes extremely troublesome.

Means and Effects for Solving the Problems The present invention relates to an improvement in the adjustment mechanism of a hydraulic lash adjuster that overcomes the above-mentioned difficulties. In a hydraulic lash adjuster that is applied to a valve train that performs opening/closing control via a rocker arm to adjust tappet clearance, a lash adjuster that passes through a holding part of the hydraulic lash adjuster. The insertion hole is formed to be oriented within an angle range of 45° or more and 90° or less with respect to the cylinder axis, and the base of the lash adjuster insertion hole has a larger diameter than the intermediate and tip portions of the insertion hole. and a stopper bolt is screwed to the base of the lash adjuster insertion hole via an adjusting means for varying the installation depth of the hydraulic lash adjuster. It is.

In the present invention, as mentioned above, the base of the lash adjuster insertion hole is formed to have a larger diameter than the middle and tip parts, so the lash adjuster can be removed very easily by simply removing the stopper bolt. This eliminates the need to remove the Rocker arm shaft, intake/exhaust valve stems, etc. that need to be adjusted for tappet clearance, and as a result, maintenance and
Inspection work can be carried out extremely easily within a short period of time.

In addition, in the present invention, as described above, the lash adjuster insertion hole is formed to be oriented within an angle range of 45° or more and 90° or less with respect to the cylinder axis, so the dimension of the cylinder head in the cylinder axial direction can be reduced. can do.

Embodiment Hereinafter, an embodiment of the present invention illustrated in FIGS. 2 to 6 will be described.

FIG. 2 is a vertical cross-sectional rear view of a cylinder head section showing a valve operating mechanism of a horizontally opposed four-cycle gasoline engine for a motorcycle.

The cylinder head 1 is formed with an intake port 2 and an exhaust port 3.
An intake valve 4 and an exhaust valve 5 are provided so that they can be opened and closed, respectively. Compression coil springs 6 are disposed to engage with the intake/exhaust valves 4, 5, respectively, and the compression coil springs 6 are connected to the intake/exhaust valves 4, 5 in a direction that blocks the intake/exhaust ports 2, 3.
is energized.

Also, cylinder head 1 and camshaft holder 7
A camshaft 8 rotatably supported by
It is located between the stems 4a and 5a of the exhaust valves 4 and 5. The camshaft 8 is connected to a timing sprocket on the crankshaft via a timing chain at a timing sprocket 10 pivotally attached to the end of the camshaft 8.

Furthermore, a plurality of rocker arm shafts 11 are rotatably supported on a rocker arm shaft holder 7a integrally with the camshaft holder 7. This rocker arm shaft 11 has a large diameter journal 12, a small diameter journal 14, and each journal 12, 14.
The rocker arm 15 is tiltably supported on each eccentric shaft 13 (see FIG. 3).

A large notch 12A is formed in each large-diameter journal 12 from the outer periphery toward the center of rotation, and a small notch 12B is formed at a position offset from this large notch 12A in the axial direction.

On the other hand, a hydraulic lash adjuster (hereinafter simply referred to as a lash adjuster) is installed in a lash adjuster insertion tube 7c as a lash adjuster insertion hole formed in a plurality of lash adjuster holding portions 7b integrated with the camshaft holder 7. 20 (referred to as an adjuster) is inserted. The latch adjuster 20 includes a latch adjuster body 21 which is a hollow body with an open end and a bottom, a hollow plunger 22 that is slidably inserted into the adjuster body 21, and a hollow plunger 22 that is slidably inserted into the adjuster body 21. A cap 23 fitted to the open end, that is, a tip, a plunger spring 25 that urges the plunger 22 upward via a check ball case 24, and a check ball fitted to the base opening (valve seat) of the plunger 22. The check ball spring 27 is interposed between the check ball case 24 and the check ball 26 so as to press the check ball 26.

The oil reservoir R (communicated with the oil pump) formed in the camshaft holder 7 and the latch adjuster insertion cylinder 7c are communicated via a communication port 7d. The lubricating oil forced into the thrust adjuster insertion tube 7c is fed into the hollow portion of the plunger 22 through communication ports formed in the walls of the adjuster body 21 and the plunger 22.

Further, a stopper bolt 28 is screwed into the open end screw portion of the latch adjuster holding portion 7b via a shim 29 serving as an adjusting means. Therefore, the base of the adjuster body 21 is supported by the tip of the stopper bolt 28.
(See Figure 2).

On the other hand, an auxiliary shaft 30 is slidably fitted into an auxiliary shaft insertion cylinder 7f formed in a plurality of auxiliary shaft holding parts 7e integrated with the camshaft holder 7, and the auxiliary shaft 30 is fitted with an auxiliary spring 3.
1 and supported by an auxiliary shaft support bolt 32. A shim 3 is provided between the auxiliary shaft support bolt 32 and the seat of the auxiliary shaft holding portion 7e.
3 is inserted (see Figure 2).

The detailed shapes of the auxiliary shaft 30 and the auxiliary shaft support bolt 32 are as shown in FIG. 4 and FIG. Both members 30 and 32 are integrally connected to each other in a locking relationship with an auxiliary spring 31, as shown in FIG.

Thus, the cap 23 attached to the tip of the lash adjuster 20 inserted into the lash adjuster insertion tube 7c engages with the large notch 12A formed in the large diameter journal 12, and the auxiliary shaft is inserted. The tip of the auxiliary shaft 30 inserted into the tube 7f engages with a small notch 12B formed in the large diameter journal 12, and both members 20 and 30 move the large diameter journal 12 in the direction of arrow B. It acts to rotate.

This embodiment is configured as described above,
When the engine is running, lubricating oil discharged from the oil pump is fed into the oil reservoir R through a predetermined oil passage, and the lubricating oil in the oil reservoir R flows through the communication port 7d, the adjuster body 21, and the plunger 22. It is supplied to the inner chamber 22A of the plunger 22 through communication ports formed in each wall. The lubricating oil in the inner chamber 22A is supplied to the adjuster body 2 through the base opening of the plunger 22.
The oil is sent to the high pressure chamber 1 (the chamber housing the plunger spring 25), and the high pressure chamber is filled with lubricating oil.

Therefore, in FIG. 2, the intake valve 4 (or
When the exhaust valve 5) is closed, the Rocker arm shaft 1
1 through the plunger 22 and cap 23,
It receives the elastic force of the plunger spring 25 and also receives the elastic force of the auxiliary spring 31 via the auxiliary shaft 30, and rotates in the direction of arrow B in FIG. is pressed toward the cam 9 and the stem end 4b of the intake valve 4 (or exhaust valve 5), thereby eliminating the tappet clearance.
When the plunger 22 moves forward due to the elastic force of the plunger spring 25 and the pressure in the high pressure chamber decreases, the check ball 26 separates from the base opening (valve seat) of the plunger 22 and lubricates the inner chamber 22A. Oil is supplied into the high pressure chamber, filling the high pressure chamber with lubricating oil.

Furthermore, when a valve opening force is applied to the rocker arm 15 due to the lift action of the cam 9, that force is applied to the eccentric shaft 15 as a force in the opposite direction to the direction of arrow B in FIG.
3, the plunger 22 receives a force in the backward direction, but the check ball 26
Since the base opening of 2 is blocked, hydraulic pressure is generated in the high pressure chamber, and the plunger 22 is prevented from retreating, and the eccentric shaft 13 is prevented from rotating. Thus,
The Rocker arm 15 tilts around the eccentric shaft 13,
The intake valve 4 (or exhaust valve 5) is opened against the elastic force of the compression coil spring 6.

Next, the characteristic points of this embodiment will be listed.

By changing the thickness of the shim 29 inserted between the stopper bolt 28 and the seat of the latch adjuster holding portion 7b, the stopper bolt 2
Optimal positioning of the latch adjuster 20 is performed at the tip end surface of the shim 29, and the accumulated machining dimensional errors (or tolerances) of each member constituting the valve mechanism are adjusted using the shim 29.
It is possible to absorb it. Therefore, the forward and backward stroke of the plunger 22 can be set smaller than that of the conventional plunger, and the lash adjuster 20 can be made smaller.

By changing the plate thickness of the shim 33 inserted between the auxiliary shaft support bolt 32 and the seat of the auxiliary shaft holding part 7e, the auxiliary spring 31
It is possible to finely adjust the elasticity of the ball.

When replacing the latch adjuster 20, simply replace the stopper bolt 20 without removing other parts such as the camshaft holder 7 and camshaft 8.
The work is easy and efficient because all you have to do is remove it.

Since the auxiliary shaft 30 and the auxiliary shaft support bolt 32 are integrally connected by the auxiliary spring 31, the auxiliary shaft 30 can be removed without removing the camshaft holder 7, camshaft 8, etc., improving maintenance work efficiency. At the same time,
The number of parts is reduced.

It is possible to measure the pulp timing by removing the stopper bolt 28 and equipping the lash adjuster insertion tube 7c with a simple measuring jig.

Effects of the invention As is clear from the above explanation, the invention has the following effects:
Since the holding member of the hydraulic lash adjuster is equipped with an adjustment means that changes the installation depth of the hydraulic lash adjuster, the installation depth of the hydraulic lash adjuster can be changed and adjusted using the adjustment means. However, it is possible to absorb the integrated machining dimensional errors (or tolerances) of each member that makes up the valve mechanism,
The plunger stroke of the hydraulic latch adjuster can be reduced, and the dimension of the cylinder head in the cylinder axial direction can be reduced, and as a result, the internal combustion engine can be made smaller.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal side view showing a known valve operating mechanism for a four-stroke gasoline engine, and Fig. 2 is a longitudinal rear view showing a valve operating mechanism for a horizontally opposed four-cycle gasoline engine according to an embodiment of the present invention. Figure 3 is a top view of the cylinder head of the four-stroke gasoline engine with the cylinder head cover removed, Figure 4 is a side view of the auxiliary shaft support bolt used in the valve mechanism, and Figure 5. 6 is a side view of the auxiliary shaft, and FIG. 6 is a cutaway side view of essential parts showing a state in which the auxiliary shaft and the auxiliary shaft support bolt are integrally coupled. 1...Cylinder head, 2...Intake port,
3...Exhaust port, 4...Intake valve, 4a...Stem, 4b...Stem end, 5...Exhaust valve, 5a
...Stem, 6...Compression coil spring, 7...
...Camshaft holder, 7a...Lotsuker arm shaft holder, 7b...Lush adjuster holding part, 7
c... Latch adjuster insertion tube, 7d... Communication port, 7e... Auxiliary shaft holding part, 7f... Auxiliary shaft insertion tube, 8... Cam shaft, 9... Cam, 1
0...Timing sprocket, 11...Rotzker arm shaft, 12...Large diameter journal, 12A...
...Large notch, 12B...Small notch, 13...Eccentric shaft, 14...Small diameter journal, 15...Rocker arm, 20...Hydraulic lash adjuster, 2
1...Adjuster body, 22...Plunger, 22A...Inner chamber, 23...Cap, 24
...Check ball case, 25...Plunger spring, 26...Check ball, 27...
Check ball spring, 28...stopper bolt, 29...shim, 30...auxiliary shaft,
31...Auxiliary spring, 32...Auxiliary shaft support bolt, 33...Shim.

Claims (1)

[Scope of utility model registration request] Hydraulic lash adjusters are used in valve train systems that control the opening and closing of the intake and exhaust valves of internal combustion engines via rocker arms using cams that rotate in synchronization with the rotation of the engine, and adjust tappet clearance. The lash adjuster insertion hole passing through the holding part of the hydraulic lash adjuster is formed oriented within an angle range of 45° or more and 90° or less with respect to the cylinder axis, and the lash adjuster insertion hole The base of the lash adjuster is formed to have a larger diameter than the intermediate and distal ends of the insertion hole, and the base of the lash adjuster insertion hole is provided with adjustment means for varying the installation depth of the hydraulic lash adjuster. An adjustment mechanism for a hydraulic latch adjuster, characterized in that a stopper bolt is screwed through the stopper bolt.