JPH0355767Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a lash adjuster used in a valve drive device of an engine.

(b) Prior Art Conventionally, in an overhead cam type valve drive device, in order to eliminate valve clearance and eliminate the need to adjust the valve clearance, a valve shaft is always attached to one swinging end of the rocker arm while the engine is running. Some valves are equipped with a lash adjuster that comes into contact with the valve and automatically responds to deformation due to thermal expansion of the valve.

For example, conventional lash adjusters include:
As shown in Utility Model Application No. 57-66206, pressure oil supplied from an oil tank is made to flow from above the plunger toward a low pressure chamber inside the plunger through a predetermined passage. The pressurized oil is guided into the high pressure chamber, and the volume of the high pressure chamber automatically changes according to the deformation of the valve, maintaining airtightness when opening and closing the valve, and also prevents reaction from the valve shaft. There are known valve lift valves that maintain a constant valve lift amount by increasing their rigidity in response to force.

However, in such a device, the pressure oil flows into the low pressure chamber inside the plunger from above the plunger, so it flows into the plunger together with the pressure oil, and when the engine is stopped, it is not discharged to the outside but flows into the upper part of the low pressure chamber. The air bubbles that have accumulated in the engine will be introduced into the high pressure chamber together with newly supplied pressurized oil when the engine is started next time, causing problems such as generating abnormal noise and disrupting the valve lift amount.

(c) Purpose This invention was developed with attention to the above-mentioned circumstances, and by preventing air bubbles from flowing into the high-pressure chamber, it is possible to prevent the above-mentioned abnormal noises and deviations in valve lift amount. It is an object of the present invention to provide a lash adjuster capable of eliminating the following inconveniences.

(D) Structure In order to achieve the above object, the present invention includes a lifter body that is slidably provided at one swinging end of the rocker arm and whose tip abuts the base end of the valve shaft;
a bottomed cylindrical plunger slidably provided on the inner periphery of the lifter body, a low pressure chamber formed within the plunger, and a high pressure chamber formed between the tip wall of the lifter body and the bottom wall of the plunger; a communication passage provided in the bottom wall of the plunger to communicate the low pressure chamber and the high pressure chamber; and a check valve that opens and closes the communication passage to only allow fluid to flow from the low pressure chamber to the high pressure chamber; and an introduction path provided on the peripheral wall of the plunger for introducing pressurized oil supplied from the oil pump through the supply path in the rocker arm into the low pressure chamber, the introduction path being provided on the peripheral wall of the plunger. The introduction path is opened toward the communication path, and the supply path is separated by a spacer provided at the upper end of the plunger, and a hole is provided in the spacer, and the hole is communicated with the exhaust path. It is characterized by

With such a configuration, the air bubbles in the low pressure chamber gather at the upper part of the low pressure chamber and are discharged together with some oil into the exhaust path through the hole provided in the spacer. Note that when the engine is stopped, there is no oil flow, so air bubbles often remain at the top of the low-pressure chamber, but the introduction path is provided on the peripheral wall instead of the top of the plunger. Moreover,
Since the passage is opened toward the communication passage, the pressure oil supplied from this introduction passage into the low pressure chamber when the engine is started is directly guided toward the high pressure chamber without passing through the bubble retention portion. Therefore, the possibility that air bubbles will be guided into the high pressure chamber together with the newly introduced pressure oil is extremely low.

In particular, since the supply path in the rocker arm is divided by the spacer, the entire amount of oil fed into the supply path is introduced into the low pressure chamber toward the high pressure chamber, and then the spacer It passes through the hole and is discharged from the exhaust path. Therefore, it is possible to reliably discharge the air bubbles that have collected or remained in the upper part of the low pressure chamber to the outside from the low pressure chamber.

(E) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

An engine 1 is provided with an overhead cam type valve drive device 2. This valve drive device 2 has a rocker shaft 3 swingably support a rocker arm 4, a tip 5a of one swinging end 5 of the rocker arm 4 abuts a cam 6, and the other swinging end 7 A latch adjuster 8 is provided at
The base end 11a of 1 is brought into contact with the base end 11a of 1. In such a valve driving device 2, the lash adjuster 8 has the following configuration.
A lifter body 12 is slidably provided on the swinging end 7 of the rocker arm 4 with the tip 12a abutting the base end 11a of the valve shaft 11, and a plunger 13 is slidable on the inner circumference 12b of the lifter body 12. It is set up in The plunger 13 has a bottomed cylindrical shape with a bottom wall 13a, and a low pressure chamber 14 is formed in the interior space of the plunger 13. Further, a high pressure chamber 15 is provided between the tip wall 12c of the lifter body 12 and the bottom wall 13a of the plunger 13.
is formed. Further, a communication passage 16 is bored in the bottom wall 13a of the plunger 13, and these low pressure chambers 1
4 and a high pressure chamber 15 are communicated with each other. Further, a check valve 17 is provided in the high pressure chamber 15. This check valve 17 includes a check ball 18 that is removably provided in the communication path 16, and a check ball 18.
It has a spring 19 that presses the spring 19 against the communication path 16, and a support member 21 that supports the spring 19. Further, 22 is a spring that mainly causes the lifter body 12 to protrude. Further, an introduction path 23 is provided at a predetermined location on the peripheral wall 13b of the plunger 13, and oil is supplied from an unillustrated oil tank through a supply path 24 provided in the rocker shaft 3 and a supply path 25 provided in the rocker arm 4. Pressure oil is introduced into the low pressure chamber 14. Here, the introduction passage 23 is provided obliquely downward from the outer peripheral surface to the inner peripheral surface of the peripheral wall 13b of the plunger 13, and is opened toward the communication passage 16. Note that 26 is an exhaust system path. This exhaust system path 26 includes a hole 28 bored in a spacer 27 provided in contact with the upper end of the plunger 13, an exhaust path 29 provided in the rocker arm 4, and also provided in the rocker arm 4. It has an air chamber 31 that communicates the exhaust path 29 with the hole 28, and a pinball 32 that connects the exhaust path 29 with the external space of the rocker arm 4. Further, as shown in FIG. 2, the spacer 27
The supply path 25 in the rocker arm 4 is divided.
33 is a blind ball that closes the end of the exhaust path 29. In addition, 34 is a cylinder, 35 is a combustion chamber,
36 is a fuel port, and 37 is a spring for closing the valve 9.

Next, the action of this lash adjuster 8 will be explained.

When the engine 1 is in operation, the rocker arm 4 swings as the cam 6 rotates to open and close the valve 9. When the engine 1 is started, the oil pump (not shown) is connected to the supply path 2 in the rocker shaft 3.
4 and the pressure oil fed through the supply path 25 in the rocker arm 4 is transferred from the introduction path 23 to the plunger 13.
It is introduced into the internal low pressure chamber 14. The pressure oil introduced in this way flows into the communication passage 1 against the pressing force of the check valve 17.
6 into the high pressure chamber 15. When the lash adjuster 8 swings as the rocker arm 4 swings while the high pressure chamber 15 is filled with pressure oil, the lash adjuster 8 presses the valve stem 11 and opens the valve 9. At this time, a repulsive force by the spring 37 acts on the lash adjuster 8. When the lifter body 12 tries to retreat due to the repulsive force, the pressure oil in the high pressure chamber 15 tries to flow back to the low pressure chamber 14, and the check ball 18 is pressed against the communication path 16 by the backflow pressure to close the communication path 16. do.
Therefore, the pressure oil is confined in the high pressure chamber 15 and becomes high pressure, and has a rigidity close to that of a metal material. Therefore, the high pressure chamber 15 maintains a constant volume despite the repulsive force of the spring 37, thereby keeping the valve lift amount constant. In addition, even if the valve 9 is deformed, such as thermal expansion of the valve 9 during operation of the engine 1 or contraction of the valve 9 due to temperature drop after the engine 1 is stopped, the position of the lash adjuster 8 that should accommodate such deformation is also determined. is automatically adjusted by increasing or decreasing the volume due to an increase or decrease in the amount of pressurized oil in the high pressure chamber 15 of the lash adjuster 8, so there is no need for the effort of adjustment as in a valve drive device that provides a valve clearance. .

Furthermore, in the case of the lash adjuster 8, since the introduction passage 23 is provided on the peripheral wall of the plunger 13 and opened toward the communication passage 16,
Even if the air bubbles that have flowed into the low pressure chamber 14 together with the pressure oil remain in the upper part of the low pressure chamber 14 when the engine 1 is stopped, the air bubbles will flow into the low pressure chamber 14 without being mixed with the newly introduced pressure oil when the engine 1 is started. is discharged from. Then, the air passes through the hole 28 of the spacer 27, the air chamber 31, the exhaust path 29, and the pinhole 32 that constitute the exhaust system path 26, and is discharged to the external space of the rocker arm 4. Therefore, as in the conventional system, the air bubbles accumulated in the low pressure chamber when the engine is stopped flow into the high pressure chamber together with the pressure oil introduced into the low pressure chamber when the engine is started, weakening the rigidity of the high pressure chamber and causing abnormalities. It is possible to eliminate inconveniences such as noise generation and valve lift amount. In particular, since the supply path 25 in the rocker arm 4 is divided by the spacer 27, the entire amount of oil fed into the supply path 25 is introduced into the low pressure chamber 14 toward the communication path 16. Thereafter, it can be discharged from the hole 28 of the spacer 27 via the exhaust system path 26. Therefore, the air bubbles that collect and remain in the upper part of the low pressure chamber 14 can be reliably discharged to the outside of the lash adjuster 8.

It should be noted that the present invention is of course not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

(f) Effects As explained above, the present invention prevents air bubbles from flowing into the high-pressure chamber, thereby preventing a decrease in the rigidity of the high-pressure chamber, thereby reducing the occurrence of abnormal noise and deviations in valve lift. Therefore, it is possible to provide a lash adjuster that can eliminate the above inconveniences.

In particular, the device of the present invention has a hole in the spacer provided at the upper end of the plunger so that air bubbles in the low pressure chamber can be led to the exhaust path through this hole, so air bubbles can accumulate inside the low pressure chamber. It is possible to prevent this from happening. Moreover, since the introduction passage is provided on the peripheral wall of the plunger and opens toward the communication passage, when the engine is started, the pressure oil supplied from the introduction passage causes air bubbles to accumulate in the upper part of the low pressure chamber. can be effectively prevented from getting involved. Therefore, it is possible to extremely reduce the possibility that air bubbles will be introduced into the high-pressure chamber, thereby reliably preventing a decrease in the rigidity of the high-pressure chamber, and effectively eliminating problems such as abnormal noise and irregular valve lift. It is something that can be done. Further, the spacer divides the supply path inside the rocker arm, and after the entire amount of oil passing through this supply path is introduced into the low pressure chamber in the manner described above, it is discharged to the outside of the rocker arm via an exhaust path or the like.
Therefore, the air bubbles in the low pressure chamber can be reliably discharged to the outside of the rocker arm, and problems caused by air bubbles can be effectively eliminated.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, with FIG. 1 being a schematic front view and FIG. 2 being an enlarged front sectional view. 2... Valve drive device, 4... Locker arm, 7...
... Swinging end, 8... Lush adjuster, 12...
...Lifter body, 13...Plunger, 14...
Low pressure chamber, 15...High pressure chamber, 16...Communication path, 17
... Check valve, 23 ... Inlet path, 25 ... Supply path,
27...Spacer.

Claims (1)

[Scope of utility model registration request] a lifter body that is slidably provided at one swinging end of a rocker arm of an overhead cam type valve drive device and whose tip abuts a base end of a valve shaft;
A bottomed cylindrical plunger slidably provided on the inner periphery of the lifter body, a low pressure chamber formed within the plunger, and a high pressure chamber formed between the tip wall of the lifter body and the bottom wall of the plunger. and,
a communication passage provided in the bottom wall of the plunger to communicate the low pressure chamber and the high pressure chamber; and a check valve that opens and closes the communication passage to only allow fluid to flow from the low pressure chamber to the high pressure chamber; A lash adjuster comprising: an introduction passage provided on a peripheral wall of the plunger for introducing pressure oil supplied from an oil pump through a supply passage in the rocker arm into the low pressure chamber; An introduction path provided on the peripheral wall is opened toward the communication path, and the supply path is separated by a spacer provided at the upper end of the plunger, and a hole is provided in the spacer, and the hole is communicated with the exhaust path. A ratchet adjuster that is characterized by the fact that