JPH0429046Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention relates to an engine valve drive device.
This invention relates to a rocker arm equipped with a hydraulic tappet, which transmits force from a camshaft to a valve.

(Prior Art) Generally, as a valve drive device for an engine, a rocker arm type is provided in which a rocker arm is swingably provided, one end of the rocker arm receives force from a camshaft, and this force is transmitted from the other end of the rocker arm to the valve. things are known.
In such a valve drive device, a gap occurs between the rocker arm and the camshaft or the valve due to expansion and contraction of the valve stem due to the thermal load applied to the valve, and displacement of the valve set position due to wear of the valve seat. Gaps that occur in the valve train cause the opening and closing timing of the valves to be out of order, and excessive loads are applied to the above-mentioned components, shortening the life of the engine.

Conventionally, in order to eliminate such a gap in a valve train, a hydraulic tappet for transmitting the force from the camshaft to the valve is provided on the rocker arm, as disclosed in Japanese Patent Laid-Open No. 53-16113, for example. At the same time, a reserve chamber is formed to supply oil to the hydraulic chamber of the hydraulic tappet, and the hydraulic tappet is expanded by the hydraulic pressure so that the hydraulic tappet is always in contact with the valve, thereby supplementing the gap. is proposed.

(Problem to be solved by the invention) By the way, in the valve driving device proposed above, since the hydraulic tappet is attached to the rocker arm, the reserve chamber is formed in a fluid-tight manner inside the rocker arm, and the hydraulic tappet and the reserve chamber are formed in a liquid-tight manner. It communicates with the chamber to enable supply of oil.

Therefore, when assembling the above-mentioned hydraulic tappet, air gets mixed into the reserve chamber when the hydraulic tappet is assembled into the rocker arm, and if this air gets mixed into the hydraulic chamber of the hydraulic tappet at the time of startup, the force from the camshaft due to its compressibility increases. A problem arises in that the hydraulic tappet contracts when transmitting the pressure to the valve, and as a result, the above-mentioned gap compensation effect is impaired.

In addition, in order to ensure liquid tightness, the wall thickness between the reserve chamber and the outer surface of the rocker arm must be set to a predetermined thickness or more, taking into account processing accuracy, so only those with a relatively small volume can be used. This made it difficult to use large-capacity hydraulic tappets.

The present invention was devised in view of the above, and its purpose is to form separate members in the reserve chamber and the rocker arm, and to integrate the hydraulic tappet into the rocker arm so that the hydraulic tappet can be assembled into the rocker arm. To prevent air from entering a reserve chamber during loading, and to increase the volume of the reserve chamber without being affected by the machining accuracy of a rocker arm, making it possible to use a large-capacity hydraulic tappet.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention includes a hydraulic tappet at one end of the rocker arm that transmits the force from the camshaft to the valve, and a hydraulic tappet provided above the hydraulic tappet. The present invention is directed to a valve drive device for an engine equipped with a reserve chamber for supplying oil to a hydraulic chamber of the hydraulic tappet, and a through hole with a circular cross section is provided at one end of the rocker arm to vertically penetrate the rocker arm. A downstream end of an oil passage for introducing oil into the reserve chamber is open at the upper wall surface of the through hole, and an upper bottom portion is provided at the upper part of the through hole integrally with the upper end of the tappet main body of the hydraulic tappet. A cylindrical reserve chamber constituent member having a shape is fitted, a reserve chamber is constituted by the reserve chamber constituent member and the upper end of the tappet body, and the downstream end of the oil passage is attached to the side wall of the reserve chamber constituent member. An oil hole is provided which communicates with the reservoir chamber and introduces oil into the reserve chamber.

(Function) With the above configuration, the reserve chamber is formed by the upper end of the tappet main body of the hydraulic tappet, and the cylindrical reserve chamber which is provided integrally with the upper end of the tappet main body and has an upper base and has an oil hole in the side wall. When the hydraulic tappet and the reserve chamber constituent members are assembled into the rocker arm, they can be assembled with the reserve chamber filled with oil, thereby preventing air from entering the reserve chamber. At the same time, the wall thickness of the rocker arm portion around the reserve chamber can be made as thin as possible, so it is possible to set the volume of the reserve chamber relatively large.

Furthermore, a through hole with a circular cross section is provided at one end of the rocker arm and passes through the rocker arm in the vertical direction, and the downstream end of the oil passage for introducing oil into the reserve chamber is opened in the upper wall surface of the through hole. , the oil passage can be drilled using the upper end opening of the through hole.

Further, since the cylindrical reserve chamber component having the upper bottom is fitted into the upper part of the through hole, there is no need for a member to close the opening formed on the upper surface of the rocker arm after drilling the oil passage.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a valve drive device for an overhead cam type engine.
In the figure, reference numeral 1 denotes a camshaft rotatably supported on the cylinder head (not shown) of the engine and rotationally driven by the engine crankshaft (not shown), and the camshaft 1 has a cam surface. 1a is formed. 2 is a rocker shaft extending parallel to the camshaft 1 and supported on the cylinder head; 3 is a rocker arm swingably supported by the rocker shaft 2; one end (left end in the figure) of the rocker arm 3 is connected to the rocker shaft 1; The rocker arm 3 is in contact with the cam surface 1a of the camshaft 1, and as the camshaft 1 rotates, the rocker arm 3 is swung by a predetermined angle.

On the other hand, the other end (the right end in the figure) of the rocker arm 3 is in contact with the upper end of a valve stem 4a of an intake/exhaust valve 4 that opens and closes the intake/exhaust port via a hydraulic tappet 6 (described later). As the rocker arm 3 swings, it is pressed against the biasing force of a valve spring 5 that biases the valve 4 in the valve closing direction, thereby opening and closing the valve 4 at a predetermined timing.

A hydraulic tappet 6 for transmitting the force from the camshaft 1 to the valve 4 is provided at the other end of the rocker arm 3, which is in contact with the upper end of the valve stem 4a of the valve 4. Further, a reserve chamber component 14 constituting a reserve chamber 7 is provided in the rocker arm 3 corresponding to the hydraulic tappet 6, and the reserve chamber 7 is connected to the rocker arm 3 by an oil passage 8 formed in the rocker arm 3. It is in communication with the bearing part 3a, and the oil fed to the rocker arm bearing part 3a is guided through an oil passage 8 and supplied to the hydraulic tappet 6 (hydraulic chamber 11 to be described later).

As shown in FIG. 2, the hydraulic tappet 6 includes a bottomed cylindrical tappet body 9 that is fitted into an insertion hole formed in the rocker arm 3 and is assembled therein, and a tappet body 9 that slides vertically in a fluid-tight manner into the tappet body 9. The tappet body 9 and the plunger 10 are provided with a plunger 10 that is movably arranged, and the hydraulic chamber 11 is
The hydraulic chamber 11 is communicated with the reserve chamber 7 through a communication hole 9a opened at the bottom of the tappet body 9.

Further, a spring 12 is compressed between the tappet body 9 and the plunger 10 so as to press the plunger 10 downward. Further, in the hydraulic chamber 11, there is a check valve 13 which includes a check ball that can be seated in the communication hole 9a and a spring that biases the check ball in the seating direction.
is installed.

Therefore, when a valve clearance, which is a gap in the valve train, occurs, the plunger 10 is moved toward the valve 4 by the spring 12, and the oil in the reserve chamber 7 is released into the check valve due to the pressure drop in the hydraulic chamber 11. When the valve 13 is opened, the oil passes through and flows into the hydraulic chamber 11, thereby extending the entire hydraulic tappet 6, and the plunger 10 comes into contact with the upper end of the valve stem 4a of the valve 4 to supplement the above-mentioned valve clearance. It is configured to stop oil flowing into the hydraulic chamber 11 when the pressure in the hydraulic chamber 11 increases. In addition, the hydraulic chamber 11
Even if the hydraulic tappet 6 is pressed from above and below, the oil flowing into the hydraulic tappet 6 will flow back into the reserve chamber 7 due to the action of the check valve 13, and the hydraulic tappet 6 will not be compressed. The force is reliably transmitted to the valve 4.

As a feature of the present invention, as shown in FIG. 2, there is a reserve chamber constituent member 14 made of a bottomed cylindrical thin sheet metal that constitutes the reserve chamber 7.
The reserve chamber constituting member 14 is formed integrally with the tappet main body 9 by press-fitting its open end 14a into a recess 9b formed at the bottom of the tappet main body 9. There is.

In this case, the rocker arm 3 has a first fitting hole 15 with a circular cross section that opens at the bottom surface of the rocker arm 3, and a second fitting hole 15 with a circular cross section that extends upward from the upper end of the first fitting hole 15 and opens at the top surface of the rocker arm 3. A through hole consisting of a fitting hole 16 is provided, and the tappet body 9 of the hydraulic tappet 6 is fitted into the first fitting hole 15, which is the lower part of the through hole, and the second fitting hole, which is the upper part of the through hole. The reserve chamber constituent member 14 is fitted into the fitting hole 16 .

Incidentally, reference numeral 17 denotes an oil hole opened in the side surface of the reserve chamber constituent member 14 corresponding to the oil passage 8;
Reference numeral 18 denotes an air vent hole opened in the bottom surface of the reserve chamber constituent member 14.

Next, to explain the operation of the above embodiment,
The reserve chamber 7 is constituted by a reserve chamber constituent member 14 which is a separate member within the rocker arm 3, and the reserve chamber constituent member 14 is integrally formed into the tappet body 9 by press fitting. With the chamber component 14 and the hydraulic chamber 11 of the tappet body 9 filled with oil, the integrated hydraulic tappet 6 and reserve chamber component 14
can be fitted and assembled into the first and second fitting holes 15 and 16. Therefore, it is possible to suppress and prevent air from entering the reserve chamber 7, thereby preventing contraction of the hydraulic tappet 6 due to air being sucked into the hydraulic chamber 11, and improving the complementarity of the valve clearance of the hydraulic tappet 6. can be ensured.

In addition, the reserve chamber 7 includes a reserve chamber component 1
Since the liquid tightness is ensured by 4, it is possible to form the wall thickness of the rocker arm 3 portion that forms the second insertion hole 16 as thin as possible,
Furthermore, the reserve chamber 7 can be extended upward, and as a result, the size of the reserve chamber component 14 and the volume of the reserve chamber 7 can be set large, and a large-capacity hydraulic tappet 6 can be used. becomes.

Further, the upper end of the oil passage 8 is connected to the second fitting hole 16.
The second insertion hole 1 is open at the upper wall surface of the second insertion hole 1.
Since the reserve chamber forming member 14 is fitted into the rocker arm 6, it becomes easy to drill the oil passage 8 from above, and there is no need for a member to close the opening formed on the upper surface of the rocker arm 3 after drilling. Become.

Furthermore, if the reserve chamber constituent member 14 is made of a thin sheet metal as in the above embodiment, it will be easy to manufacture and the manufacturing cost will be low.

In addition, in the above embodiment, the reserve chamber component 14
Although the tappet body 9 is integrated with the tappet body 9 by press-fitting, it may also be done by welding or other joining means. In addition, the hydraulic tappet 6 and the reserve chamber 7
was installed at the valve side end of the Rocker arm 3,
Conversely, it may be provided at the end on the camshaft side. Furthermore, the present invention can be applied not only to the overhead cam type valve drive device as in the above embodiment, but also to various other valve drive devices using rocker arms.

(Effects of the invention) As explained above, according to the invention, the reserve chamber is formed in a cylindrical shape having an upper end of the tappet main body of the hydraulic tappet, and an upper base integrally provided with the upper end, and formed on the side wall. Since the hydraulic tappet and the reserve chamber constituent member are formed by the reserve chamber constituent member having an oil hole, the hydraulic tappet and the reserve chamber constituent member can be assembled into the rocker arm with the reserve chamber filled with oil, thereby preventing air from entering the reserve chamber. In addition, the wall thickness of the rocker arm portion around the reserve chamber can be made as thin as possible, and the volume of the reserve chamber can be set to be large, thereby improving the reliability of the valve drive device.

Furthermore, a through hole with a circular cross section is provided at one end of the rocker arm and passes through the rocker arm in the vertical direction, and the downstream end of the oil passage for introducing oil into the reserve chamber is opened in the upper wall surface of the through hole. The oil passage can be drilled using the upper end opening of the through hole, and since the cylindrical reserve chamber component having the upper bottom is fitted into the upper part of the through hole, the oil passage can be drilled. Since there is no need for a member to close the opening formed on the upper surface of the rocker arm after machining, the workability of the oil passage that introduces oil into the reserve chamber is extremely good.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, with FIG. 1 being a general schematic diagram and FIG. 2 being a vertical cross-sectional view of the main part. 1...Camshaft, 3...Rotzker arm,
4... Valve, 6... Hydraulic tappet, 7... Reserve chamber, 8... Oil passage, 9... Tappet body, 10... Plunger, 11... Hydraulic chamber, 14
... Reserve chamber constituent member, 15 ... First fitting hole (lower part of the through hole), 16 ... Second fitting hole (upper part of the through hole), 17 ... Oil hole.

Claims (1)

[Claim for Utility Model Registration] A hydraulic tappet for transmitting force from the camshaft to the valve is installed at one end of the rocker arm, and a reserve chamber is provided above the hydraulic tappet for supplying oil to the hydraulic chamber of the hydraulic tappet. A valve drive device for an engine equipped with a through hole having a circular cross section that vertically passes through the rocker arm at one end of the rocker arm, and supplying oil to the reserve chamber through an upper wall surface of the through hole. The downstream end of the oil passage is open, and a cylindrical reserve chamber constituent member that is provided integrally with the upper end of the tappet main body of the hydraulic tappet and has an upper bottom is fitted into the upper part of the through hole, and the reserve chamber A reserve chamber is constituted by the component and the upper end of the tappet body, and an oil hole is provided in the side wall of the reserve chamber component to communicate with the downstream end of the oil passage and introduce oil into the reserve chamber. An engine valve drive device characterized by: