JPH0544524B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a direct-acting valve mechanism that controls intake and exhaust operations of an internal combustion engine.

2. Description of the Related Art A direct-acting valve mechanism operates a valve while the internal combustion engine is running by means of a valve clearance that is provided to absorb thermal expansion of the cylinder or valve train due to heat generated by the internal combustion engine and smooth the operation of the valve. The lash adjustment mechanism, which is incorporated into the valve train for the purpose of avoiding noise (hitting noise) in the train, is installed between the cam and the valve, and the lift operation of the cam is adjusted to the push rod or This mechanism is configured to transmit power directly to the valve without using a locking arm, etc., and this mechanism is used in internal combustion engines operated at high speeds due to the advantage that the inertial mass of the entire valve train can be reduced. It is beginning to be applied to

Therefore, an overview of a conventional direct-acting valve mechanism will be explained based on FIG. 3.

In FIG. 3, 1 is a cam consisting of a reference circular portion 1a and a lift portion 1b, 2 is a tappet body, 3 is an intake or exhaust port, and 4 is an intake or exhaust valve for opening and closing the port 3.

The tappet main body 2 includes a substantially cylindrical tappet guide part 7 forming a side part and a tappet head part 9 sealing an axially upper shaft 8 of the tappet guide part 7, and is used as a cylinder head part of an internal combustion engine. The reference circular portion 1a of the cam 1 is slidably disposed within a tappet guide hole 6 formed in the tappet head 9, and the reference circular portion 1a of the cam 1 is brought into sliding contact with a cam sliding surface 10 formed at the outer end of the tappet head 9. Inside the tappet body 2, a cylinder hole 11 is provided which is formed in the axial direction, and a bottomed cylindrical plunger 12 is inserted into the cylinder hole 11, with its bottom 12a being the furthest from the tappet head 9. They are inserted so that they separate. A predetermined clearance is provided inside the plunger 12 so that the plunger 12 is separated into two chambers: a first oil chamber 15 on the side of the tappet head 9 and a second oil chamber 16 on the bottom 12a side of the plunger 12. Hold C and seat plunger 1
3 is slidably inserted. Said second oil chamber 1
6, the air flows from the first oil chamber 15 to the second oil chamber 1 through the through hole 14 formed in the seat plunger 13.
A check valve 17 is provided to allow flow of hydraulic oil only toward the valve 6. The check valve 17 is constructed mainly of a check ball 28 and a check spring 27 that biases the check ball 28 in the direction of closing the through hole 14. In addition, the seat plunger 13 is disposed in the second oil chamber 16 at the bottom 12 of the plunger 12.
A return spring 18 is loaded to bias the return spring 18 in a direction away from a.

A valve stem 19 of an intake or exhaust valve 4 that opens and closes the intake or exhaust port 3 is in axial contact with the lower surface of the plunger bottom 12a. A valve spring 22 biases the intake or exhaust valve 4 in the direction of closing the intake or exhaust port 3 via a spring receiving member 30 fixed to one end 19a of the valve stem 19.

The tappet main body 2 is provided with an oil introduction hole 23 for introducing hydraulic oil, and the hydraulic oil introduced from an oil pump (not shown) to an oil gear gallery 25, etc. is transferred to an annular oil chamber 26 formed inside the tappet main body 2 and a seat. The oil is introduced into the first oil chamber 15 through a cutout oil passage 33 provided in the plunger 13.

Note that 31 is a stopper that prevents the plunger 12 from coming off.

In the conventional direct-acting valve mechanism having the above configuration, when the internal combustion engine rotates, the cam 1 rotates, and the reference circular portion 1a formed on the cam 1 is connected to the tappet that constitutes the tappet body 2. Since the cam sliding surface 10 of the head 9 is pressed, the entire tappet body 2 moves downward while being guided by the tappet guide hole 6. Therefore, the valve 4 is pushed down via the plunger 12, so that the valve 4 opens the intake or exhaust port 3. As a result, plunger 1
The spring force of the valve spring 22 applied to the tappet body 2 through the valve spring 2 increases, the oil pressure in the second oil chamber 16 formed in the plunger 12 is increased, and part of the hydraulic oil in the second oil chamber 16 is increased. The part is plunger 1
2 and the outer circumferential surface of the seat plunger 13.
6 and escapes into the first oil chamber 15 via a notched oil passage 33 provided at the upper end edge of the seat plunger 13.
Therefore, the plunger 12 is connected to the tappet body 2.
It sinks by a small amount α relative to the

As the cam 1 further rotates, the spring force of the valve spring 22 applied to the tappet body 2 gradually decreases and finally reaches zero as the valve 4 closes the port 3. It is pushed back by the α dimension. As a result, the oil pressure in the second oil chamber 16 becomes lower than the oil pressure in the first oil chamber 15, and as a result, the hydraulic oil in the first oil chamber 15 resists the spring force of the check spring 27 and moves toward the check ball 28. Press down and open hole 1
4 and is sucked into the second oil chamber 16 from the first oil chamber 15.

In this way, the plunger 12 is pushed back to its original position which brings the valve clearance of the valve train as a whole to zero. Here, if the amount of oil in the first oil chamber 15 decreases for some reason, the hydraulic oil from the oil pump (not shown) will be transferred to the oil gear rally 25, the oil introduction hole 23, the annular oil chamber 26, and the notched oil passage 33. Since the first oil chamber 15 is forcibly supplied with oil through the hydraulic fluid, this hydraulic oil is supplied into the second oil chamber 16 for lash adjustment.

Note that if the dimensions of the valve train change due to changes in the operating conditions of the internal combustion engine and a valve clearance occurs, the plunger 12 is set in advance so that the spring force of the return spring 18 causes the plunger 12 to reduce the valve clearance to zero. Move and then
As described above, during operation, the plunger 12
By repeating the sliding movement of the dimensions, the valve clearance is set to zero and the valve mechanism operates smoothly.

By the way, in the conventional direct-acting valve mechanism having such a configuration, the annular oil chamber 2 formed in the tappet body 2 is passed from the oil pump through the oil introduction hole 23.
6, a system is adopted in which hydraulic oil is forcibly supplied. Therefore, while the internal combustion engine is operating, hydraulic oil is supplied from the oil pump into the annular oil chamber 26 of the tappet body 2, and the inside is filled with hydraulic oil, but when the internal combustion engine stops operating, The supply of hydraulic oil from the oil pump into the annular oil chamber 26 is stopped. Therefore, the hydraulic oil once stored in the annular oil chamber 26 also flows back to the oil gear gallery 25 side through the oil introduction hole 23, and as a result, most of the hydraulic oil flows out from the annular oil chamber 26 to the oil gear gallery 25 side. The oil only remains in the first and second oil chambers 15 and 16. At this time, some of the cams 1 have their lift portions 1b
comes into contact with the tappet head 9 and stops. When stopped in this state, the valve 4 has the port 3 open, so the valve spring 22 presses the plunger 12 upward, causing the second oil chamber 1 to open.
The hydraulic oil in the chamber 16 becomes high, and the hydraulic oil in the chamber 16 flows out into the annular oil chamber 26 through the clearance C. Finally, the seat plunger 13 comes into contact with the bottom 12a of the plunger 12, and the second oil Chamber 16 has the smallest volume. Then, when the internal combustion engine starts operating again, a predetermined time is required until the hydraulic oil is supplied from the oil pump to the annular oil chamber 26, so that the oil remains in the first oil chamber 15. When using a small amount of hydraulic oil, the flow from this first oil chamber 15 to the second oil chamber 1
The amount of hydraulic oil that is replenished into the tank 6 and used as a medium for lash adjustment therein is insufficient. Therefore, there were cases where air was sucked into the second oil chamber 16 from the first oil chamber 15. If such a situation occurs, the air will be compressed in the second oil chamber 16, which will not only make it impossible to perform sufficient lash adjustment, but also cause damage to the cam 1 and tappet head 9.
Also, since a gap is formed between the portion 9 and the seat plunger 13, there is a drawback that a tapping sound is generated there.

Note that in order to compensate for the delay in the supply of hydraulic oil into the annular oil chamber 26 at the time of starting the internal combustion engine, it is possible to increase the volume of the first oil chamber 15.
In order to increase the volume inside the first oil chamber 15, the entire seat plunger 13 must be increased in size, which causes problems such as an increase in the size of the entire valve mechanism and its weight. Moreover, it cannot be adopted because it goes against the development direction of reducing the size and weight of the entire valve mechanism.

Means for Solving the Problems In order to solve these conventional problems, the present invention provides a tappet that is fitted into a cylinder hole formed in the tappet body so as to be slidable in the axial direction with respect to the hole wall. The outer periphery of the inserted bottomed cylindrical plunger has an upper opening edge extending at least to a position above the formation position of the oil introduction hole for guiding hydraulic oil into the tappet body, and an outer peripheral surface of the plunger that extends into the cylinder hole. A cylindrical outer cylinder portion with a bottom is integrally formed and is slidably connected to the outer cylinder portion, and an annular oil storage chamber is formed inside the outer cylinder portion.

Function The present invention having such a configuration temporarily stores most of the hydraulic oil filled in the annular oil chamber in the oil storage chamber in the outer cylindrical portion formed on the outer periphery of the plunger when the internal combustion engine stops operating. It works like this.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. Components that are the same as those of the conventional example are given the same reference numerals, and redundant explanation thereof will be omitted.

FIG. 1 is a sectional view of essential parts showing an embodiment of a direct-acting valve mechanism according to the present invention.

As shown in FIG. 1, a bottomed cylindrical plunger 12 is fitted into a cylinder hole 11 formed in the tappet body 2 so as to be slidable in the axial direction against the hole wall. An outer cylindrical portion 20 having a bottomed cylindrical shape is integrally formed on the outer periphery of the plunger 12 . The upper opening edge 20a of the outer cylindrical portion 20 extends to a position at least above the formation position of the oil introduction hole 23 for introducing the hydraulic oil into the tappet body 2, and the outer circumferential surface 20b thereof is It is slidably brought into sliding contact with the cylinder hole 11 . Therefore, an annular oil storage chamber 21 is formed inside this outer cylinder portion 20 to temporarily store most of the hydraulic oil filled in the annular oil chamber 26 when the internal combustion engine stops operating. has been done. Further, inside the plunger 12, there is a seat plunger 13 for dividing the inside of the plunger 12 into a first oil chamber 15 on the side of the tapepet head 9 and a second oil chamber 16 on the side of the bottom 12a of the plunger 12. It is inserted with a predetermined clearance C. At the upper end of this seat plunger 13, a cylindrical portion 12b of the plunger 12 is provided.
A head plunger 34 is placed thereon, and includes a cylindrical portion 34a that surrounds the cylindrical portion 34a, and a lid portion 34b that covers an opening at the upper end of the cylindrical portion 34a. An air vent groove 38 is formed in the upper surface of the lid portion 34b of the head plunger 34 in the diametrical direction. In addition, the lid portion 34 of this head plunger 34
At least one communication hole 36 is formed in b to communicate the groove 38 with the inside of the head plunger 34. Furthermore, an air vent hole 37 is formed in the tapepet head 9 to communicate the outside of the tappet body 2 with the inside of the air vent groove 38. It is formed on a vertical line passing through the center 0.

In such a configuration, when the operation of the internal combustion engine is stopped, the supply of hydraulic oil from the oil pump to the annular oil chamber 26 through the oil introduction hole 23 is stopped, and the annular oil chamber 26 is filled. A part of the hydraulic oil flows out to the oil gear gallery 25 side through the oil introduction hole 23. However, the hydraulic oil present below the upper opening edge 20a of the outer cylindrical part 20 formed on the outer periphery of the plunger 12 is temporarily stored in the oil storage chamber 21 formed inside the outer cylindrical part 20. That will happen. Therefore, at the time of restarting the internal combustion engine, since a large amount of hydraulic oil is already stored in the storage chamber 21, the oil pump, the annular oil chamber 26, the gap 35 between the head plunger 34 and the plunger 12 are , the required amount of hydraulic oil can be immediately replenished into the second oil chamber 16 via the cutout oil passage 33 and the first oil chamber 15, respectively. Therefore, since a delay in the supply of hydraulic oil can be prevented, there is no need to increase the volume of the first oil chamber 15, and the present invention can be advantageously applied to a high-speed rotating internal combustion engine.

In addition, according to the embodiment, if the oil introduction hole 23
Even if the hydraulic oil containing air flows into the annular oil chamber 26 and air starts to accumulate above the inside, the head plunger 34 keeps the sheet so as to cover the upper end openings of the plunger 12 and the seat plunger 13. Since the air is placed on the upper end of the plunger 13, the air has a lower specific gravity than the hydraulic oil.
Unless it passes through the route shown by the broken line in FIG. 1, it will not enter the first oil chamber 15. Therefore, the first oil chamber 15
The amount of air mixed in can be suppressed to a very small amount.
In addition, an air vent hole 37 is formed in the tapepet head 9, and an air vent groove 38 is formed in the upper surface of the lid portion 34b of the head plunger 34, which communicates with the hole 37. The air that has started to accumulate in the air can be quickly discharged to the outside through the groove 38 and the air vent hole 37. Therefore, it is possible to prevent air from entering the first oil chamber 15 from the annular oil chamber 26.

Next, FIG. 2 is a sectional view of a main part showing another embodiment of the present invention.

In this example, unlike the previous example,
The head plunger is not placed in the upper opening of the plunger, and the volume of the first oil chamber 15 is formed to be sufficiently larger than the volume of the first oil chamber 15 in the case of the above embodiment. It is a point.

Even with this configuration, as in the case of the embodiment described above, when the internal combustion engine stops operating, the required amount of hydraulic oil can be stored inside the outer cylindrical portion 20 formed on the outer periphery of the plunger 12. In, the first
Since the volume of the oil chamber 15 is formed to be sufficiently large, sufficient hydraulic oil can be stored in the first oil chamber 15. Therefore, when restarting the internal combustion engine, the first oil Air remaining in the upper part of the chamber 15 can be prevented from entering the second oil chamber 16 as much as possible. In addition, in this embodiment, the tappet head 9 is
Since the air vent hole 37 is formed above the oil introduction hole 23, the air remaining in the upper part of the oil introduction hole 23 and the upper part of the oil storage chamber 21 is removed from the oil introduction hole 23 into the first oil chamber. When hydraulic oil is supplied to the valve 15 side, it can be pushed out from the air vent hole 37, thereby preventing the occurrence of valve clicking noise due to air intrusion.

Effects of the Invention As is clear from the above description, according to the present invention, since the bottomed cylindrical outer cylinder part is integrally formed on the outer periphery of the plunger, when the internal combustion engine stops operating,
A required amount of hydraulic oil can be temporarily stored in an oil storage chamber formed inside the outer cylinder. Therefore, when restarting the internal combustion engine, hydraulic oil can be immediately replenished into the second oil chamber via the first oil chamber.
Therefore, it is possible to obtain desired valve lift characteristics, and to prevent the occurrence of valve clicking noises due to air intrusion.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing one embodiment of a direct acting valve mechanism according to the present invention, FIG. 2 is a sectional view of a main part showing another embodiment of the invention, and FIG. FIG. 3 is a sectional view showing a valve train. DESCRIPTION OF SYMBOLS 1... Cam, 2... Tappet body, 4... Valve, 5... Cylinder head, 6... Tappet guide hole, 7... Tappet guide, 9... Tappet head, 11... Cylinder hole, 12... ...Plunger, 12a...Bottom, 13...Seat plunger, 14...Through hole, 15...First oil chamber, 16...
Second oil chamber, 17...Check valve, 20...Outer cylinder part, 20a...Upper opening edge, 20b...Outer peripheral surface, 21...Oil storage chamber, 23...Oil introduction hole, 26
...Annular oil chamber.

Claims (1)

[Claims] 1. A tappet body that is slidably inserted into a tappet guide hole formed in the cylinder head of an internal combustion engine, and a tappet that slides in the axial direction against the hole wall within the cylinder hole formed in this tappet body. A cylindrical plunger with a bottom that can be fitted into the plunger; A seat plunger is slidably inserted into the interior of the plunger with a predetermined clearance so as to be separated into two chambers; A check valve disposed within the second oil chamber to allow flow of hydraulic oil only toward the second oil chamber, and a check valve disposed on the lower surface of the bottom of the plunger,
A substantially cylindrical tappet guide portion comprising an intake or exhaust valve having a valve stem that makes elastic contact in the axial direction, and forming a side portion of the tappet body has an annular shape with one end formed by the tappet guide portion and the seat plunger. An oil introduction hole is formed that communicates with the oil chamber and the other end communicates with the oil pump, and hydraulic oil is supplied from the oil introduction hole to the second oil chamber via the annular oil chamber and the first oil chamber. In a direct-acting valve mechanism that opens and closes the intake or exhaust valve in response to the rotation of a cam that slides in contact with the tappet head using a medium as a medium, on the outer periphery of the plunger,
integrally forming a bottomed cylindrical outer cylinder part whose upper opening edge extends to a position at least above the position where the oil introduction hole is formed, and whose outer circumferential surface is slidably contacted with the cylinder hole; A direct-acting valve mechanism characterized by forming an annular oil storage chamber inside an outer cylinder.