JPH0326244Y2 - - 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.

In consideration of the above two problems, the present invention improves the arrangement structure of the oil reservoir chamber and also improves the shape of the plunger.

Prior Art Figure 6 shows a conventional example of a valve mechanism having an automatic hydraulic valve gap 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 latch. It is Ajiastha. Figure 7 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 biases the plunger 52 outward from the body 51. Further, from the oil passage 6 shown in FIG. 6, 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 for controlling 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 for holding 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. 8 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. 7, 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 until it reaches the uppermost end. This is the maximum clearance from the plunger position of the latch adjuster when the cam base circle is in contact with the rocker arm.
In other words, when the engine is restarted from such a state and the cam position that contacts the rocker arm reaches the base circle in the first cam cycle, the plunger expands accordingly, Trying to remove the dry lashes all 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 the engine is started when there is no oil in the oil passage, a large amount of air is sucked into the oil reservoir chamber, resulting in a large amount of oil mixed with air. The oil in the high pressure chamber will lead to an extreme decrease in rigidity, and there is a possibility that the oil in the high pressure chamber will not be able to function normally. Furthermore, when the engine is tilted, or when the hydraulic latch adjuster is mounted on the engine at a tilt, the oil reservoir chamber will have a lower liquid level because the plunger 52 is tilted as shown in FIG. There is an air layer above the horizontal line, 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 volume, resulting in the same undesirable situation as in the former case. This will result in inhibition of functions that are not present.

Means for Solving the Problems The present invention has been made to solve these problems, and includes providing a protrusion on the lower surface of the plunger and forming a guide surface for the elastic body on the outer periphery of the protrusion. The high pressure chamber forming surface for sending air from the center of the bottom surface of the protrusion to the lower end of the outer peripheral sliding surface of the plunger is a horizontal surface or an upwardly inclined surface, and the latch adjuster and the bottom of an oil reservoir chamber provided separately are connected to the oil connection. It is characterized by being connected by a 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 bottom of the chamber, so the lash adjuster has no opportunity to suck in air, and the high pressure of the plunger is reduced. Since there is no concave surface on the chamber forming surface, even if air exists in the high pressure chamber, there is no space for it to accumulate, so stable operation can be achieved, and at the same time, the lash adjuster, which does not have an oil sump chamber, does not have a plunger Since the cylinder head is short, the depth at which the latch adjuster is attached to the cylinder head can be shortened, which increases the space above the intake and exhaust ports, making it possible to reduce the degree of curvature. Efficient intake and exhaust can be achieved when exchanging exhaust gas.

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 hollow cylinder with a bottom and has an open end 71a at the top and a closed end 71b at the bottom, and a solid plunger is installed in the hollow. 72 is fitted and extends outwardly from the portion 72a;
It has a protrusion 72b. 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 in the high pressure chamber 73 and engages with the plunger protrusion 72b as a guide surface to move the plunger 72 between the body 71 and the plunger 72. The force is applied outward from the center.

The lower surface of the plunger 72 has an outer circumferential sliding surface that hangs down outside the abutting portion of the elastic body 74, and a portion of the outer circumferential sliding surface has an abutting portion as shown in FIGS. 2 and 3. A slit with parallel vertices is formed to prevent air from accumulating in the abutment area. (Corresponding to Claim 3) Although not shown in the drawings, in FIG. 2, it is also possible to cut out the entire circumference instead of using a slit to create a shape that prevents air retention. (Corresponding to Claim 2) 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. Even if some air gets mixed in, there is no space for the air to stagnate, so the air will dissipate to the outside through the sliding surface with the body.

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 5 are partially cutaway side views showing a state different from Fig. 1. be. Fig. 6 is a partially cutaway side view showing a conventional example;
Figure 7 is an enlarged view of the main parts, and Figures 8 to 10.
This figure is a partially cutaway side view in a different state from FIG. 6. The symbols of the main parts in the figure are as follows. 1... Locker arm, 2... Valve, 3... Valve spring, 4... Cam, 7... Hydraulic latch adjuster, 8... Intake/exhaust port, 9... Oil sump chamber, 10... Oil connection aisle.

Claims (1)

[Claims for Utility Model Registration] 1. A bottomed hollow cylindrical body having an oil hole at the bottom, and a plunger slidably fitted into the body to form a high pressure chamber between the bottom inner surface and the body. , an elastic body provided in the high pressure chamber to urge the plunger to move away from the open end of the body; a check valve also provided in the high pressure chamber for controlling opening and closing of the oil hole; and holding the check valve. In a hydraulic latch adjuster comprising a check valve cage, a projection is provided on the lower surface of the plunger, and a guide surface for the elastic body is formed on the outer periphery of the projection.
The high pressure chamber forming surface from the center of the bottom surface of the protrusion to the lower end of the outer peripheral sliding surface of the plunger is a horizontal surface or an upwardly inclined surface, and the latch adjuster and the bottom of an oil reservoir provided separately are connected to the oil connection. Automatic correction device between hydraulic valves connected by a passage. 2 The bottom surface of the protrusion provided on the lower surface of the plunger is formed to be flat, and the lower surface from the elastic body abutting portion to the outer peripheral sliding surface of the plunger is flat. Hydraulic valve interval = automatic correction device. 3. The bottom surface of the protrusion provided on the lower surface of the plunger is formed into a flat surface, and a slit having an apex parallel to the contact portion is formed on the outer peripheral sliding surface of the plunger that is formed to hang down from the elastic body contact portion to the outside. A hydraulic valve gap automatic correction device according to claim 1 of the registered utility model claim.