JPS622246Y2 - - Google Patents

Description

[Detailed description of the invention] In order to automatically adjust the clearance between the intake and exhaust valves and the rocker arm in the closed state in an overhead valve type valve train of an internal combustion engine, conventionally,
A lash adjuster was used.

This project concerns a latch adjuster used in a DOHC (double overhead cam) internal combustion engine with a forward-inclined cylinder. The object of the present invention is to provide an oil supply structure that can reliably supply hydraulic oil to a hydraulic lash adjuster during startup.

An embodiment of the present invention illustrated in the drawings will be described below.

1 is the cylinder head of a four-stroke gasoline engine for motorcycles, where the cylinder is tilted forward.
An intake port 2 and an exhaust port 3 are formed in the cylinder head 1, and an intake valve 4 and an exhaust valve 5 are slidably fitted in the cylinder head 1 so that the intake and exhaust ports 2 and 3 can be opened and closed freely. ing.

Further, compression coil springs 6 are attached to the intake and exhaust valves 4 and 5, respectively, in a direction that always closes the intake and exhaust ports 2 and 3.

Furthermore, a cam 7 is pivotally supported on the upper rear side of the intake valve 4 and the upper front side of the exhaust valve 5, and the cam 7 is connected to a crankshaft (not shown) via a chain and a sprocket, and is connected to the rotation of the crankshaft. The cam 7 is rotationally driven in synchronization.

Furthermore, the cam 7 is sandwiched between the intake and exhaust valves 4 and 5.
Latch adjuster insertion tubes 9 are formed on the opposite side of the valves 4 and 5 to be substantially parallel to the valves 4 and 5 and directed upward.
0 are fitted in such a way that they can appear and disappear freely.

Moreover, one end of the rocker arm 8 is swingably supported on the tip spherical bearing portion 13 of the plunger 12 in the latch adjuster 10, and the center upper surface of the rocker arm 8 contacts the cam 7, and the other end of the rocker arm 8 The ends are adapted to come into contact with the top ends of the intake and exhaust valves 4 and 5.

The latch adjuster 10 includes an adjuster body 11, a plunger 12 slidably fitted into the adjuster body 11, and a plunger 12 fitted onto the upper end of the adjuster body 11 so as not to protrude beyond a certain length. Retainer cap 14 and check ball case 15
a plunger spring 16 that urges the plunger 12 upward through the plunger spring 16; and a check ball spring 18 that is interposed in the check ball case 15 and the check ball 17 so as to press the check ball 17 against the lower end valve seat 12a of the plunger 12. It's getting more and more familiar.

Furthermore, oil reservoirs 19f and 19r are located at the upper front side of the front lash adjuster insertion tube 9f and the upper rear side of the rear lash adjuster insertion tube 9r.
An oil supply passage 20 directed diagonally downward is communicated from the oil reservoirs 19f and 19r to the side wall of the lash adjuster reservoir cylinder 9.

Furthermore, one end of a bifurcated portion of an oil supply pipe 21 is connected to the upper part of each of the oil reservoirs 19f, 19r, and the other end of the oil supply pipe 21 is connected to a discharge port of an oil pump (not shown).

Air vent holes 22 are connected to the tops of the oil reservoirs 19f and 19r, respectively, so that air in the oil stored in the oil reservoirs 19 is discharged into the cylinder head through the air vent holes 22. .

Since the illustrated embodiment is configured as described above, when the engine is in operation, oil is supplied from the oil pump (not shown) to the oil reservoirs 19f, 19r via the oil supply pipe 21, and the oil reservoirs 19f, 19r The oil inside is supplied to the latch adjuster insertion tube 9 through the oil supply passage 20.
f, 9r, and is supplied to the reservoir chamber 12c in the plunger 12 through holes 11a, 12b provided in the adjuster body 11 and the plunger 12. The oil in the reservoir chamber 12c is sent to the high pressure chamber 11b of the adjuster body 11 via the check ball 17, and the high pressure chamber 11b is filled with oil, and the remaining oil is sent to the passage 12.
The lubricant is supplied to the sliding portion between the rocker arm 8 and the tip spherical bearing portion 13 of the plunger 12 through d, thereby lubricating the sliding portion.

When a clearance is created between the rocker arm 8, the intake and exhaust valves 4 and 5, and the cam 7, the plunger 12 is raised by the spring force of the plunger spring 16, and due to the pressure drop in the high pressure chamber 11b. The check ball 17 is separated from the valve seat 12a of the plunger 12 and the reservoir chamber 12c
The oil inside is supplied into the high pressure chamber 11b.

Furthermore, when the cam ridge of the cam 7 approaches the rocker arm 8 and the rocker arm 8 is pushed down by the cam ridge, the upper end of the plunger 12 is also pushed down, so the oil in the high pressure chamber 11b is pressurized to a high pressure. Thus, the fulcrum portion of the rocker arm 8 is rigidly supported.

By repeating these operations, the plunger 12 is moved up and down, and the fulcrum of the rocker arm 8 is changed.
Tappet clearance is always maintained at zero.

In this way, the tappet clearance is automatically adjusted, and the noise of the valve mechanism is reduced.

Furthermore, since the oil reservoirs 19f and 19r are attached to each of the lash adjuster insertion tubes 9f and 9r at a height that has a certain head H with respect to each of the lash adjuster insertion tubes 9f and 9r, Oil is evenly supplied from the oil reservoirs 19f and 19r to each latch adjuster insertion cylinder 9f and 9r.
The latch adjuster insertion tubes 9f and 9r can operate equally.

In addition, if the engine is out of operation for a long period of time, if a single oil reservoir is installed, when the oil flows out through the air vent hole in the latch adjuster below the oil reservoir, the oil in the upper latch adjuster will leak out. Since the oil in the oil supply passage to the adjuster also leaks out, when the engine starts, the upper latch adjuster only has a reservoir chamber inside the oil latch adjuster, and if the initial start fails, Due to insufficient oil supply, air flows into the high pressure chamber, causing abnormal noise. However, in the above embodiment, the lash adjuster insertion tubes 9f, 9
The oil reservoir 1 has a certain head H at each r.
9f and 19r are attached, so that oil can be evenly distributed in the oil supply passages 20f and 20r, and even when the engine is started, there is no shortage of oil supply, and air can flow into the high pressure chamber. This prevents abnormal noise from occurring.

In this proposal, the intake and exhaust valves of a forward-tilting DOHC internal combustion engine are controlled by a cam that rotates in synchronization with the rotation of the engine.
A valve train that opens and closes via a rocker arm.In an oil supply structure that has a predetermined volume space in the middle of the oil supply passage that supplies hydraulic oil to the hydraulic latch adjuster used in the support part of the rocker arm, The space is provided on the upstream side of each of the intake-side hydraulic lash adjuster and the exhaust-side hydraulic lash adjuster, and above the respective hydraulic lash adjusters. Even if the heights of both hydraulic lash adjusters on the exhaust side are different, the relative heights of both lash adjusters and each volume space can be equalized, and the By equalizing the oil supply, both latch adjusters can be operated equally, and even when the engine is stopped, oil is evenly supplied to both latch adjusters to prevent air from entering. Therefore, it is possible to prevent abnormal noise from occurring.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view illustrating an embodiment of the oil supply structure for the hydraulic lash adjuster according to the present invention;
FIG. 2 is a longitudinal sectional side view of the lash adjuster in the same embodiment. 1...Cylinder head, 2...Intake port, 3
...Exhaust port, 4...Intake valve, 5...Exhaust valve,
6... Compression coil spring, 7... Cam, 8...
... Locker arm, 9 ... Latch adjuster insertion tube, 10 ... Latch adjuster, 11 ... Adjuster body, 12 ... Plunger, 13 ...
Tip spherical bearing part, 14...retainer cap,
15...Check ball case, 16...Plunger spring, 17...Check ball, 18
... Check ball spring, 19 ... Oil reservoir, 20 ... Oil supply passage, 21 ... Oil supply pipe, 22 ... Air vent hole, 23 ... Air vent hole.

Claims (1)

[Scope of utility model registration request] A valve operating system that opens and closes the intake and exhaust valves of a forward-tilting DOHC internal combustion engine via a rocker arm using a cam that rotates in synchronization with the rotation of the engine. In the middle of the oil supply passage that supplies hydraulic oil to the adjuster,
In an oil supply structure having a predetermined volumetric space, the same volumetric space is located on the upstream side of each of an intake-side hydraulic lash adjuster and an exhaust-side hydraulic lash adjuster. A structure for supplying oil to a hydraulic latch adjuster, which is characterized by being provided above the adjuster.