JPH0217131Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application The present invention is a hydraulic latch adjuster that automatically corrects the valve gap in a valve train of an internal combustion engine using hydraulic pressure and the elastic force of an elastic member, especially an end-pivot type actuator. This invention relates to improvements in hydraulic lash adjusters used in valve mechanisms.

Hydraulic latch adjusters are desirably small in size and shape because they need to be housed in limited installation locations without taking up space as part of efforts to make internal combustion engines smaller and lighter. Therefore, efforts must be made to minimize the dimensions of each component. Therefore, the volumes of the high-pressure chamber and oil reservoir chamber that store oil must be determined to the minimum required size and shape, but conventional hydraulic lash adjusters have an oil reservoir chamber inside the plunger due to their structure. Therefore, the current situation is that there is a limit to minimization of dimensions.

Another important thing is to always maintain rigidity in the pressure oil in the high pressure chamber of the hydraulic lash adjuster. If a large amount of air is mixed into the oil supplied to the high pressure chamber, the rigidity of the pressure oil will be significantly reduced, which may prevent the valve from functioning properly. must be carefully devised to prevent this. As a countermeasure to this problem, a means is needed to promote separation of oil and air in the oil sump chamber.

The present invention is an improvement in the arrangement structure of the oil sump chamber in consideration of the above two problems.

7 shows a conventional example of a valve train having a hydraulic valve gap automatic correction device, in which 1 is a rocker arm, 2 is a valve, 3 is a valve spring, 4 is a cam, and 5 is a hydraulic locking mechanism. It is Ajiastha. Figure 8 shows the details of the hydraulic lash adjuster 5 on the body 51.
is a bottomed hollow cylindrical body having an open end 51a at the upper part and a closed end 51b at the lower part, a hollow plunger 52 is fitted in the hollow thereof, and has a part 52a extending outward from the hollow cylinder. The high pressure chamber 53 is formed between the closed end 51b of the body 51 and the plunger 52,
An elastic body 54 is located within the high pressure chamber 53 and urges the plunger 52 outward from the body 51. Further, from the oil passage 6 shown in FIG. 7, oil is introduced into the oil reservoir chamber 55 through an annular oil groove 51c and an oil hole 51d provided on the outer periphery of the body 51, and an oil hole 52b provided in the plunger 52 and communicating with the groove. I'm trying to guide you. In addition, the oil reservoir chamber 55 and the high pressure chamber 5
A check valve 57 that controls the opening and closing of the oil hole 56 between the high pressure chamber 53 and the high pressure chamber 53 is provided with a check valve cage 58 that holds the check valve.

Problems to be Solved by the Invention In order to improve the efficiency of engine intake and exhaust, it is desirable that the intake or exhaust port portion 8 shown in FIG. 9 has as gentle a curvature as possible in order to reduce flow loss. However, due to the presence of the hydraulic lash adjuster, the rising height of the port portion 8 is restricted, and its degree of curvature is influenced by the length of the hydraulic lash adjuster. . There is a big problem here, which requires miniaturization of the hydraulic lash adjuster.

Another problem will be discussed next.

Generally, when the engine is stopped, some valves are in an open state, and at this time, the valve springs of the valves continue to load the plunger of the lash adjuster. Therefore, the plunger continues to contract into the body from the time when the engine stops and the rotation of the cam 4 stops as shown in FIG. leaks from the gap.
In FIG. 8, the solid line of the plunger indicates the position at which the cam stops rotating, and the imaginary line indicates the position after which it moves to the uppermost end. This is due to the maximum gap from the plunger position of the latch adjuster when the cam base circle is in contact with the rocker arm, that is, a dry latch, and when the engine is restarted from this state, the first cam cycle When the position of the cam that contacts the rocker arm reaches the base circle, the plunger expands accordingly and attempts to remove the dry lash at once. At this time, the volume of the high pressure chamber increases, the pressure in the chamber decreases, and the check valve opens the oil hole to guide the oil in the oil reservoir to the high pressure chamber. However, during this rapid oil suction process, when starting the engine when there is no oil in the oil passage, a large amount of air is sucked into the oil reservoir chamber.
As a result, oil mixed with a large amount of air will be led to the high pressure chamber, and the oil in the high pressure chamber will suffer from an extreme decrease in rigidity, and there is a possibility that it will not be able to perform the function of normally operating the valve. Furthermore, when the engine is tilted, or when the hydraulic latch adjuster is mounted on the engine tilted, the oil sump chamber is
As shown in the figure, since the plunger 52 is inclined, there is an air layer above the horizontal line that is the liquid level, and when oil is supplied to the high pressure chamber, a large amount of air above the liquid level is mixed in with the reduced oil amount. As a result,
In the former case, the same undesirable functional inhibition will occur.

Means for Solving the Problems The present invention was made to solve these problems, and the oil sump chamber is separated from the low-height lash adjuster and is placed separately. In addition to reducing the size of the adjuster, the bottom of the separated oil reservoir chamber is connected to the oil hole of the lash adjuster through a communication passage.

Function When the oil reservoir chamber is filled with oil, oil is supplied from the oil reservoir chamber to the lash adjuster from the lower part of the chamber, so the lash adjuster does not have a chance to suck in air, resulting in stable operation. At the same time, the plunger of the lash adjuster, which does not have an oil reservoir, is short, so the depth at which the lash adjuster is attached to the cylinder head can be shortened, which saves space above the intake and exhaust ports. The degree of expansion and curvature can be made gentler, and therefore efficient intake and exhaust can be achieved during gas exchange between intake and exhaust.

Embodiment FIG. 1 shows a valve mechanism having a hydraulic valve gap automatic correction device, which is an example of implementing the present invention, in which 1 is a rocker arm, 2 is a valve, 3 is a valve spring, 4 is a cam, and 7 is a hydraulic valve. 9 is an oil reservoir chamber, and 10 is an oil communication passage. Figure 2 shows the details of the hydraulic lash adjuster 7. The body 71 is a low-height hollow cylinder with an open end 71a at the top and a closed end 71b at the bottom. A short solid plunger 72 is fitted therein and has a portion 72a extending outwardly therefrom. The high pressure chamber 73 is formed between the closed end 71b of the body 71 and the plunger 72, and an elastic body 74 is located within the high pressure chamber 73 to urge the plunger 72 outward from the body 71. .

An oil hole 75 for introducing oil from the outside is provided in the body closed end 71b. Also, the oil hole 7
A check valve 76 and a check valve cage 77, which control the opening and closing of the valve 5, are provided in the high pressure chamber.
As shown in FIG. 1, this hydraulic latch adjuster 7 is connected to a separate oil reservoir chamber 9 by an oil communication passage 10, and is configured to introduce oil from the lower surface through an oil hole 75. Therefore, since the plunger 72 does not have an oil reservoir built-in, it can be made smaller, and as shown in FIG. When restarting the engine after stopping with the valve open as shown in the figure,
Even if a large amount of air is sent into the oil reservoir chamber 9 from the oil passage 11, the air escapes through the upper opening 81 and is not guided to the high pressure chamber. Further, as shown in FIG. 5, even if the engine is installed at an angle and the latch adjuster 7 is arranged at an angle, the oil reservoir chamber 9 can always be installed perpendicular to the ground. Therefore, the oil level in the oil reservoir chamber 9 is on the upper surface of the opening 81, and since a sufficient amount of oil is secured, the high pressure chamber 73
can be supplied with air-free oil.

Next, another embodiment in which a plurality of lash adjusters are shared in one oil sump chamber will be shown below. Conventionally, each latch adjuster was provided with an oil sump chamber, so the cylinder head had to be made larger by the size occupied by the oil sump chamber. Therefore, as shown in FIG. 6, by sharing a plurality of lash adjusters 7 in one oil reservoir chamber 9,
Since there is a large degree of freedom in the installation location of the separate oil sump chamber, even if the hydraulic latch adjuster is installed at an angle, the oil sump chamber can be installed vertically, ensuring a sufficient amount of oil and at the same time keeping the cylinder head straight. can also be made smaller.

Effects of the invention According to the invention, it is possible to provide a compact hydraulic lash adjuster that does not suck air and always maintains rigidity, and also improves the shape of the intake and exhaust ports. It can also be made smaller and therefore contributes greatly to improving the performance of the engine.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view showing an example of the implementation of the present invention, Fig. 2 is an enlarged view of the main part, and Figs. 3 to 6 are partially cutaway side views showing a state different from Fig. 1. be. FIG. 7 is a partially cutaway side view showing a conventional example.
Figure 8 is an enlarged view of the main parts, and Figures 9 to 11.
This figure is a partially cutaway side view in a different state from FIG. 7. The symbols of the main parts in the figure are as follows: 1: Locker arm, 2: Valve, 3: Valve spring, 4: Cam, 7:
Hydraulic lash adjuster, 8: Intake and exhaust port,
9: Oil sump chamber, 10: Oil communication passage.

Claims (1)

[Claims for Utility Model Registration] 1. A low-height body in the shape of a hollow cylinder with a bottom, and a low-height body that is slidably fitted into the body and forms a high-pressure chamber between the inner surface of the bottom part. a plunger, an elastic body provided in the high pressure chamber and urging the plunger to move away from the open end of the body, a check valve also provided in the high pressure chamber and controlling opening and closing of the oil hole, and the check valve A low-height hydraulic latch adjuster is formed by the check valve cage that holds the latch adjuster, and an oil sump chamber having an upward opening in the cylinder head is formed separately from this in the vicinity of the attachment part of the latch adjuster. A hydraulic valve gap automatic correction device is formed by connecting the bottom of the oil reservoir chamber and the latch adjuster through an oil communication passage. 2. The hydraulic valve interlocking system according to claim 1, wherein an oil hole is formed in the bottom of the body of the hydraulic latch adjuster, and the oil hole is connected to the oil communication passage. correction device.