JPH0413365Y2 - - 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.

As shown in Japanese Utility Model Application No. 57-66206 as a prior art for this type of lash adjuster, pressurized oil supplied from an oil tank is introduced into the low pressure chamber of the plunger and mixed with the pressure oil. A device is known in which bubbles are separated in the low pressure chamber and discharged to the outside space from a small diameter bubble discharge hole provided at the upper end of the plunger, thereby preventing the bubbles from flowing into the high pressure chamber. There is.

However, with such a device, when the engine is stopped, the bubbles in the low pressure chamber are not discharged and become large particles and remain there, but since the bubble discharge hole is small in diameter, it is difficult to quickly discharge the bubbles when the engine is started next time. This is difficult, and some of these bubbles flow into the high pressure chamber together with the pressure oil, which tends to cause problems such as abnormal noise and irregular valve lift amounts. This inconvenience can be solved by increasing the diameter of the bubble discharge hole, but in this case, much of the pressure oil introduced into the low pressure chamber will also be discharged to the outside, and the pressure in the low pressure chamber and high pressure chamber will decrease. This causes an inconvenience in that it deteriorates and no longer performs its intended function.

(C) Purpose The present invention was developed with attention to the above-mentioned circumstances, and it solves the above-mentioned disadvantages by quickly discharging the air bubbles in the low-pressure chamber at the time of starting the engine and preventing the leakage of pressure oil. It is an object of the present invention to provide a lash adjuster that can eliminate the problem.

(D) Structure In order to achieve the above object, the present invention provides a structure in which a lifter body whose tip abuts against the base end of the valve shaft is slidable on one swinging end of the rocker arm of an overhead cam type valve drive device. A plunger is slidably provided on the inner periphery of the lifter body, and pressure oil supplied from an oil pump is introduced into a low pressure chamber formed in the plunger, and pressure oil in the low pressure chamber is provided in a communication path. In the lash adjuster, the pressure oil fed to the supply path in the rocker arm is supplied to the low pressure chamber through a check valve formed between the plunger and the lifter body. An introduction passage for the purpose of supplying water is opened in the peripheral wall of the plunger toward the communication passage, and the supply passage is separated by a spacer provided at the upper end of the plunger, so that air bubbles accumulated in the upper part of the low pressure chamber are removed from the outside. A relatively large diameter bubble discharge hole for discharging into the space is interposed between the low pressure chamber and the bubble discharge hole, and when the pressure of the low pressure chamber is lower than a predetermined value, the bubble discharge hole is relatively large. The bubble discharge hole is characterized by being provided with a valve mechanism that opens the bubble discharge hole with a large opening degree and closes the bubble discharge hole upon receiving the pressure when the pressure of the low pressure chamber is higher than a predetermined value.

With this kind of configuration, when the engine is started, the air bubbles accumulated in the upper part of the low pressure chamber are discharged to the outside through the air bubble discharge hole along with the oil. Since the introduction passage is opened in the circumferential wall of the plunger in the direction of the communication passage that communicates the low pressure chamber and the high pressure chamber, the pressure oil supplied from the introduction passage immediately after startup will not accumulate in the upper part of the low pressure chamber. There is less chance that air bubbles in the air will become entangled and lead into the hyperbaric chamber. In particular, in this case, the spacer separates the supply path in the rocker arm, so that the entire amount of oil fed to the supply path is introduced into the low pressure chamber in the manner described above. Therefore, the air bubbles staying in the upper part of the low pressure chamber can be reliably discharged to the outside of the lash adjuster using the oil introduced from the bottom side of the low pressure chamber. Moreover, since the bubble discharge hole is set larger than in the conventional type, the bubbles in the low pressure chamber are discharged to the outside more quickly after startup than in the conventional type. Furthermore, when the engine speed increases and the pressure of the pressure oil increases, the bubble discharge hole is closed by the valve mechanism, causing a large amount of pressure oil to leak outside from the bubble discharge hole. This will not cause such problems. Therefore, there is no problem such as the need to increase the capacity of the oil pump that is the source of pressure oil.

(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 provided on the inner periphery 12b of the lifter body 12. . The plunger 13 has a cylindrical shape with a bottom wall 13a, and a low pressure chamber 14 is formed in the interior space of the plunger 13. Further, the tip wall 12c of the lifter body 12 and the plunger 13
A high pressure chamber 15 is formed between the bottom wall 13a and the bottom wall 13a. Further, a communication passage 16 is bored in the bottom wall 13a of the plunger 13, and the low pressure chamber 14 and the high pressure chamber 1 are connected to each other.
It communicates with 5. Further, a check valve 17 is provided in the high pressure chamber 15. This check valve 17 is
A check ball 18 is provided in the communication path 16 so as to be able to come into contact with and separate from it, and the check ball 18 is connected to the communication path 1.
6 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 passage 23 is provided at a predetermined location on the peripheral wall 13b of the plunger 13, and oil is supplied from an unillustrated oil pump via a supply passage 24 provided in the rocker shaft 3 and a supply passage 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. Furthermore, it has a bubble discharge system 26 for discharging bubbles from the low pressure chamber to the outside space. This bubble discharge system path 26 includes a hole 28 bored in a spacer 27 provided in contact with the upper end of the plunger 13, a large diameter exhaust path 29 provided in the rocker arm 4, and a hole 28 formed in a spacer 27 provided in contact with the upper end of the plunger 13, a large diameter exhaust path 29 provided in the rocker arm 4, and Installed Nariko exhaust path 2
9 and the hole 28, and a bubble discharge hole 32 which has a larger diameter than the conventional one and communicates the exhaust passage 29 with the external space of the rocker arm 4.
and a valve mechanism 33 interposed between these bubble discharge holes 32 and the exhaust path 29. The spacer 27 separates the supply path 25 within the rocker arm 4, as shown in FIG. here,
The valve mechanism 33 connects the exhaust passage 29 and the bubble discharge hole 3.
2, a four-leaf valve plate 35 provided in this space 34 so as to be movable between the exhaust passage 29 and the bubble discharge hole 32, and this valve plate 35. It has a spring 36 that is pressed from the side of the bubble discharge hole 32 and brought into contact with the opening surface of the distal end of the exhaust passage 29 . When the valve plate 35 is in contact with the opening end surface 29a of the exhaust passage 29, as shown in FIG. is set to be larger than the opening area of the conventional bubble discharge hole, and when it is in contact with the proximal opening surface 32a of the bubble discharge hole 32, as shown in FIG. The base end opening surface 32a shown is set to be closed. Further, while the pressing force of the spring 36 is lower than a predetermined pressure in the low pressure chamber 14 (hydraulic pressure applied to the low pressure chamber 14 when the engine 1 rotates at a predetermined low speed), the pressure is applied from the low pressure chamber 14 through the exhaust path 29. The valve plate 35 is set to a value that allows the bubble discharge hole 32 to be opened at a relatively large opening degree without causing the valve plate 35 to come into contact with the bubble discharge hole 32 against the pressure applied to the valve plate 35 by the pressure applied to the valve plate 35. . FIG. 4 shows an example of the setting.

In addition, in FIG. 1, 37 is a cylinder, and 38 is a cylinder.
is the combustion chamber, 39 is the fuel port, 41 is the valve 9
This is the spring that closes the valve.

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, a supply path 2 in the rocker shaft 3 flows from an oil tank (not shown).
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 41 acts on the lash adjuster 8. When the lifter body 12 tries to retreat due to such 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, closing 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 41, thereby keeping the valve lift amount constant. Furthermore, even if the valve 9 deforms, such as thermal expansion of the valve 9 during operation of the engine 1 or contraction of the valve 9 due to a temperature drop after the engine 1 is stopped, the lash adjuster 8, which should accommodate such deformation, Since the position is automatically adjusted by increasing or decreasing the volume due to the increase or decrease in the amount of pressurized oil in the high pressure chamber 15 of the lash adjuster 8, there is no need for adjustment as in a valve driving device that provides a valve clearance. It is.

Furthermore, the air bubbles remaining in the low pressure chamber 14 when the engine 1 is stopped are removed via the air bubble discharge system 26 by the pressure of the pressure oil newly introduced into the low pressure chamber 14 when the engine 1 is started. It is discharged into the external space.
That is, when the bubbles are discharged from the low pressure chamber 14, they pass through the hole 28 of the spacer 27 and the air chamber 31 and flow into the exhaust path 29. And this exhaust path 2
9 and flows into the space 34 from the gap A between the valve plate 35 of the valve mechanism 33 that is in contact with the tip opening surface 29a, and further, from the space 34, the bubble discharge hole 3
2 and is discharged from the air bubble discharge hole 32 to the space outside the rocker arm 4.

In this way, air bubbles in the low pressure chamber 14 are discharged, but in the present invention, the valve plate 35
Since the total area of the gap A in the state where the air bubbles are in contact with the exhaust passage 29 is larger than the opening area of the conventional bubble discharge hole, and the bubble discharge hole 32 is also larger than the conventional bubble discharge hole, the The air bubbles can then be discharged to the outside space. Moreover, as the engine 1 rotates at high speed and the amount of pressure oil introduced into the low pressure chamber 14 increases, the pressure in the low pressure chamber 14 increases. The valve plate 35 is separated from the exhaust path 29 by overcoming the pressing force. When the pressure in the low pressure chamber 14 exceeds a predetermined value, the pressure causes the valve plate 35 to
2a, the bubble discharge hole 32 is closed and the pressure oil is prevented from flowing out into the external space. Therefore, even if the total area of the gap A and the diameter of the bubble discharge hole 32 are made larger than the conventional bubble discharge hole,
It has never happened that even the pressure oil introduced into the low pressure chamber is discharged and the pressure in the low pressure chamber or high pressure chamber decreases.
The lash adjuster 8 can continue to perform its intended function.

Furthermore, in the present invention, since the introduction passage 23 for guiding pressure oil into the low pressure chamber 14 is opened in the peripheral wall 13b of the plunger 13 toward the communication passage 16, the oil is supplied from the introduction passage 23 immediately after startup. It is possible to particularly reduce the possibility that air bubbles staying in the upper part of the low pressure chamber 14 will be caught up in the pressure oil and guided to the high pressure chamber 15. Moreover, the supply path 25 in the rocker arm 4
is divided by the spacer 27, so that the entire amount of oil fed to the supply path 25 is transferred to the introduction path 23.
The air is introduced into the low pressure chamber 14 from there toward the communication path 16 . Therefore, the oil introduced into the air bubbles staying in the upper part of the low pressure chamber 14 can be used to reliably adjust the lash adjuster 8.
This can effectively eliminate the problems caused by air bubbles.

Note that the configuration of the bubble discharge system is not limited to that of the embodiment described above, and may be, for example, one in which the low pressure chamber and the bubble discharge hole are directly communicated via a valve mechanism without providing an air chamber or an exhaust path.

In addition, the configuration of the valve mechanism is of course not limited to the above-mentioned embodiment, and in short, the bubble discharge hole is kept wide open at all times, and only when the pressure in the low pressure chamber exceeds a predetermined value is the bubble discharge hole opened. Any device other than the illustrated example may be used as long as it can close the bubble discharge hole in response to the static pressure of the pressure oil in the low pressure chamber or the dynamic pressure of the pressure oil that is about to be discharged from the low pressure chamber. .

Various other modifications can be made without departing from the spirit of the present invention.

(f) Effects As explained above, the present invention provides the introduction route by
Since the peripheral wall of the plunger is opened toward the communication passage, it is effective for air bubbles that accumulate at the top of the low pressure chamber immediately after the engine starts to be caught up in the pressure oil supplied from the introduction passage and guided to the high pressure chamber. can be suppressed to Moreover, since the bubble discharge hole is set larger than that of the conventional one, all the bubbles in the low pressure chamber are discharged to the outside relatively quickly after the engine is started. Therefore, it is possible to effectively prevent problems such as air bubbles entering the high-pressure chamber and causing abnormal noise or disturbing the valve lift amount. In particular, since the supply path in the rocker arm is separated by a spacer provided at the upper end of the plunger, the entire amount of oil fed to this supply path is directed from the introduction path to the communication path into the low pressure chamber. can be introduced into Therefore, the air bubbles staying in the upper part of the low pressure chamber can be reliably discharged to the outside of the lash adjuster by the oil introduced from the bottom side of the low pressure chamber, and the problems caused by air bubbles can be effectively eliminated. .

The bubble discharge hole is kept wide open when the pressure in the low pressure chamber is lower than a predetermined value, but is closed when the pressure exceeds a predetermined value. Since such a valve mechanism is provided, when the rotational speed of the engine increases and the amount of circulating pressure oil increases, the bubble discharge hole is closed by the valve mechanism. Therefore, it is possible to prevent the pressure oil in the low pressure chamber from passing through the bubble discharge hole and being unnecessarily discharged into the external space. Therefore,
Despite having a large diameter air bubble discharge hole,
Unless the capacity of the oil pump, which is the source of pressure oil, is increased, problems such as inability to maintain the pressure in the low pressure chamber at an appropriate value will not occur.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic front view, Fig. 2 is an enlarged front sectional view, Fig. 3 is a view taken in the direction of the arrow in Fig. 2, and Fig. 4 shows the valve opening characteristics of the valve mechanism. FIG. 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,
26...Bubble discharge system path, 27...Spacer, 32
... air bubble discharge hole, 33 ... valve mechanism, 35 ... valve plate.

Claims (1)

[Scope of utility model registration request] A lifter body whose tip abuts the base end of the valve shaft is slidably provided at one swinging end of the rocker arm of an overhead cam type valve drive device, and a plunger is slidably attached to the inner periphery of this lifter body. between the plunger and the lifter body through a check valve provided in a communication passage, which introduces pressure oil supplied from an oil pump into a low pressure chamber formed in the plunger, and allows pressure oil in the low pressure chamber to flow through a check valve provided in a communication path. In the lash adjuster, the introduction passage for supplying the pressure oil fed to the supply passage in the rocker arm to the low pressure chamber is directed toward the communication passage of the plunger. a relatively large-diameter bubble discharge hole opened in the peripheral wall and separated from the supply path by a spacer provided at the upper end of the plunger, for discharging bubbles accumulated in the upper part of the low-pressure chamber to an external space; Interposed between the low pressure chamber and the bubble discharge hole, when the pressure of the low pressure chamber is lower than a predetermined value, the bubble discharge hole is opened with a relatively large opening, and the pressure of the low pressure chamber is equal to or higher than the predetermined value. 1. A lash adjuster comprising: a valve mechanism that closes the bubble discharge hole upon receiving such pressure.