JPH0373726B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a rocker arm that is rotatably supported on a rocker shaft and an intermediate member that is provided on the rocker arm and that automatically adjusts valve clearance. The movement of the cam surface of the camshaft is transmitted to the valve, and in this case,
The present invention relates to a valve train for an engine that is capable of appropriately supplying oil to an intermediate member and a camshaft.

(Prior art) In an engine valve train, for example, an OHC (overhead camshaft) type valve train, under normal operating conditions, the valve seat provided between the intake and exhaust valve stem and the rocker arm and on the cylinder side. If a gap occurs between the cylinder and the valve face due to wear etc., noise will be generated due to the tapping sound at each contact surface, and such a gap between the cylinder and the valve will reduce the airtightness inside the cylinder. cause
This causes problems such as a reduction in engine output. In order to solve the problems caused by the gaps that occur between the valve stem and the Rocker arm and between the valve seat and the valve face, the contact state between the Rocker arm and the valve stem is automatically adjusted using hydraulic pressure. An intermediate member that can be used is used.

Among these, as an intermediate member that is directly attached to the rocker arm, the one shown in Japanese Utility Model Application Publication No. 57-188903 has been proposed. This intermediate member includes a cylinder formed at the valve-facing end of a rocker arm made of a light alloy material, a first member having a protrusion formed in the cylinder that abuts the valve stem, and a first member fitted within the cylinder. an oil sump chamber formed in the second member and communicating between the cylinder bottoms; A hydraulic chamber communicating with the chamber is arranged, and hydraulic pressure is applied to this hydraulic chamber from a hydraulic pressure supply source through a check valve, so that the first member receives the pressing force from the valve stem, and the pressure is applied to the second member. The intermediate member is configured to be transmitted to the bottom of the cylinder via a spacer from the press-contact portion of the member, and can be used by effectively attaching the intermediate member to the rocker arm made of a light alloy material for a long period of time.

In an engine valve train in which the rocker arm is provided with an intermediate member in this way, since the rocker arm swings around the rocker shaft, the intermediate member will inevitably move accordingly. Application of the necessary working pressure to the rocker shaft is achieved, for example, by providing an oil passage in the axial direction inside the rocker shaft and supplying oil from the oil passage to the intermediate member through communication holes formed in the rocker shaft and the rocker arm. . On the other hand, it is also necessary to supply lubricating oil to the shaft that has a cam surface that makes sliding contact with one end of the rocker arm, and for example, oil passing through an oil passage inside the rocker shaft is supplied to the camshaft. It is done by being done. Therefore, in such a case, the amount of oil required to be supplied through the oil passage inside the rocker shaft increases, making it difficult to apply sufficient working hydraulic pressure to the intermediate member, or it becomes difficult to apply sufficient hydraulic pressure to the intermediate member. In order to supply the necessary lubricating oil to the camshaft, there is a problem in that a large load is placed on the oil supply source.

(Object of the invention) The present invention has been made in view of the above points, and
A valve mechanism is provided in which the rocker arm is provided with an intermediate member that automatically adjusts the valve clearance, and the movement of the cam surface of the camshaft is transmitted to the valve via the rocker arm and the intermediate member, thereby reducing the burden on the oil supply source. An object of the present invention is to provide a valve train for an engine that can apply sufficient hydraulic pressure to an intermediate member without increasing the amount of oil and can properly supply lubricating oil to a camshaft. shall be.

(Structure of the Invention) In the engine valve train according to the present invention, the operation of the cam surface of the camshaft is transmitted to the valve.
This is carried out via a rocker arm that is swingably supported by a rocker shaft and an intermediate member provided on this rocker arm, and at this time, oil is supplied to the rocker arm according to the respective requirements of the intermediate member and the camshaft. Two types of supply holes are formed for the rocker shaft, and an oil passage extending in the axial direction is bored in the rocker shaft, and first and second through holes opening in the radial direction from the oil passage are formed, The first through hole communicates with the first supply hole of the two types of supply holes formed in the rocker arm so that hydraulic pressure can be applied to the intermediate member during a period other than when the cam is lifted, and The second through hole is configured to communicate with the second supply hole of the two types of supply holes formed in the rocker arm and supply oil to the camshaft only when the valve is lifted, that is, when the cam is lifted. Ru. With this configuration, the intermediate member is appropriately supplied with oil for applying hydraulic pressure during periods other than when the cam is lifted, and the camshaft is supplied with sufficient lubricating oil during the cam lift. It will be done.

(Example) Fig. 1 shows an outline of an example of an engine valve train according to the present invention, partially in cross section. 2 is formed, and the main parts of the OHC type valve mechanism are arranged, and below the cylinder head 1 is a cylinder block (not shown).
are arranged to form a combustion chamber 3. The cylinder head 1 is formed with an intake port 4 and an exhaust port 5, and these intake ports 4 and exhaust ports 5 extend in a curved manner from openings 4a and 5a on the combustion chamber 3 side to the outside of the cylinder head 1. and
Further, a valve seat 6 is attached to surround the openings 4a and 5a on the combustion chamber 3 side.

Further, for the openings 4a and 5a, an intake valve 7 and an exhaust valve 8, which open and close the intake port 4 and the exhaust port 5 at predetermined timings, respectively, are arranged in a V-shape. The valve 8 is guided by a valve guide 9 to move up and down in a direction perpendicular to the closing surface surrounding the openings 4a and 5a, thereby opening and closing the intake port 4 and the exhaust port 5.

Further, at the upper end portions of the intake valve 7 and the exhaust valve 8 where the valve stems 7a and 8a are provided, a spring cap 10a is engaged via a split collector 10b, and the valve spring 11 is elastically engaged with the spring cap 10a. The intake valve 7 and the exhaust valve 8 are always urged in the closed direction, that is, in the upward direction in this case. Therefore, the intake valve 7 and the exhaust valve 8 are designed to keep the intake port 4 and the exhaust port 5 closed, respectively, unless a downward pressing force is applied.

In the following description of this embodiment, in order to avoid duplication, only the valve mechanism that operates the intake valve 7 will be described, and the valve mechanism that operates the exhaust valve 8 will be described as follows, unless otherwise specified.
Since it is the same as the valve operating mechanism of the intake valve 7, the explanation will be omitted.

Next, in the upper part of the cylinder head 1,
A camshaft 12 having cam surfaces 12A and 12B corresponding to the intake valve 7 and exhaust valve 8, respectively.
is rotatably supported by the cylinder head 1 (fixed part of the engine) with its center line passing through a plane that vertically bisects the combustion chamber 3, and the timing chain is connected from the crankshaft (not shown). The rotational motion is transmitted through the etc. The cam surface 12A corresponding to the intake valve 7 is made up of the outer surface of an egg-shaped circular arc cam, and this circular arc cam has a circular base curve portion 12A ₁ and a circular base curve portion 12A ₁ .
When it rises gently and continuously from the top, it has an upheaval curve part _12A2 . Note that the cam surface 12B corresponding to the exhaust valve 8
The position of the rise valve curve part 12A ₂ is
It is made to differ from the upheaval curve portion _12A2 of the cam surface 12A corresponding to the intake valve 7 by about 180 degrees.

Further, a rocker shaft 13 is fixed and held on the cylinder head 1 at the upper part of the camshaft 12, and this rocker shaft 13 includes the following:
A rocker arm 14 is pivotably supported. The end portion 14a of the rocker arm 14 is in contact with the cam surface 12A of the camshaft 12, and the cam surface 1
2A, the end 1 of this rocker arm 14
4b of the valve stem 7 of the intake valve 7.
The air is transmitted to the intake valve 7 via the intermediate member 15 that abuts on the point a. In other words, the rocker arm 14 is a seesaw-shaped member that swings around the rocker shaft 13 between the camshaft 12 and the valve stem 7a of the intake valve 7. And camshaft 12
When driving, the end 14a of the rocker arm 14
When the cam surface 12A in sliding contact with the cam lifts,
The end portion 14a of the rocker arm 14 is pressed and raised, and the rocker arm 14 swings. At this time, the lower end of the intermediate member 15, which is provided at the end 14b of the rocker arm 14 and comes into contact with the valve stem 7a of the intake valve 7, pushes down the intake valve 7 against the elasticity of the valve spring 11. 7 is in the open state.

As shown enlarged in FIG. 2, the intermediate member 15 provided at the end 14b of the rocker arm 14 includes a cylinder member 16 that is fixed to the end 14b of the rocker arm 14 and opens downward.
and a bottomed cylindrical first member that is slidably fitted into the cylinder member 16, has a pressing portion 17a at its bottom that abuts the upper end of the valve stem 7a, and is open upward. 17 and cylinder member 1
It is located above the first member 17 in the cylinder member 16, and is fitted into the cylinder member 16 with the upper part abutting the bottom of the cylinder member 16, and has a communication hole 18a in the center and an oil reservoir therein. The second member 18 has a bottomed cylindrical shape and has a chamber 18c formed therein. A spring member 19 is compressed between the first member 17 and the second member 18.
The inside of the pressing part 17a of 7 and the bottom wall part 1 of the second member 18
8b, a hydraulic chamber 17b is formed.
Further, below the bottom wall portion 18b of the second member 18,
Check ball 20a, spring 20b and support frame 20 are placed in a position where communication hole 18a can be closed.
A check valve 20 consisting of a valve c is provided. Furthermore, on the side wall portion of the cylinder member 16,
Communication hole 18d formed in the side wall of the second member 18
A communication hole 16b that communicates with the oil reservoir chamber 18c via
is provided.

On the other hand, a first supply hole 21 is formed in the rocker arm 14 so as to communicate with the communication hole 16b of the cylinder member 16 for supplying oil to apply hydraulic pressure to the above-mentioned intermediate member 15, and further, A second supply hole 22 for supplying oil to the camshaft 12 is formed to open toward the outside of the rocker arm 14. In addition, the rocker shaft 13 has an oil supply path.
An oil passage 23 that extends in the axial direction is provided, and a first through hole 24 that extends in the radial direction from the oil passage 23 and opens and communicates with the first supply hole 21 of the rocker arm 14 during a period other than when the cam is lifted. and extends radially from the oil passage 23 to open and communicate with the second supply hole 22 of the rocker arm 14 only when the cam is lifted.
A second through hole 2 whose position is selected and drilled
5 is provided.

Under such a configuration, when oil is supplied to the intermediate member 15, when the end portion 14a of the rocker arm 14 is in contact with the base curve portion _12A1 of the cam surface 12A of the camshaft 12, that is,
During a period other than the cam lift time, the first through hole 24 is connected to the first supply hole 2 of the rocker arm 14.
1, so when oil is supplied from the oil supply source to the oil passage 23 in the rocker shaft 13, the first through hole 24 provided in the rocker shaft 13 and the rocker arm 1 are in communication with each other.
Oil at a predetermined pressure is supplied to the oil reservoir chamber 18c through the first supply hole 21 of No. 4, the communication hole 16b of the cylinder member 16, and the communication hole 18d of the second member 18, and is biased by the spring 20b to fill the communication hole. The check ball 20a that was blocking 18a is the spring 20b.
is pushed down against the elasticity of the oil reservoir chamber 18.
c communicates with the hydraulic chamber 17b. The check ball 20a detects that the oil pressure in the oil pressure chamber 17b is in the oil reservoir chamber 18.
When the oil pressure approaches c, the elasticity of the spring 20b closes the communication hole 18a, preventing oil from being discharged from the oil pressure chamber 17b to the oil reservoir chamber 18c even if the pressure on the oil pressure chamber 18b side becomes high. In this way, the oil passing through the oil passage 23 in the rocker shaft 13 provides the intermediate member 15 with an appropriate operating hydraulic pressure. Therefore, when the end portion 14a of the rocker arm 14 is in contact with the base curve portion 12A1 of the cam surface _12A of the camshaft 12, the first member 17 and the second member 18 are moved by the hydraulic pressure and the elasticity of the spring member 19. Therefore, the pressing portion 1 of the first member 17 is attached to the valve stem 7a.
7a comes into contact.

Further, when the end portion 14a of the rocker arm 14 is pressed by the rise valve curve portion _12A2 of the cam surface 12A, that is, when the cam lifts,
The first through hole 24 does not communicate with the first supply hole 21 of the rocker arm 14, and the second through hole 25 communicates with the second supply hole 22 of the rocker arm 14.
Since the camshaft 12 is in communication with
Oil is supplied only to the intermediate member 15, and no hydraulic pressure is applied to the intermediate member 15. At this time, the first member 17 receives a reaction force from the valve stem 7a, and the oil in the hydraulic chamber 17b receives a compressive force. Since the check ball 20a closes the communication hole 18a, the reaction force from the valve stem 7a is transmitted to the rocker arm 14 via the second member 18 and the cylinder member 16, and its end 14a presses the cam surface 12A. It becomes power. As a result, the valve spring 11
The pressing portion 17a of the first member 17 presses the valve stem 7a against the elastic force of the valve stem 7a, and operates the intake valve 7 in the opening direction in unison with the swinging of the rocker arm 14.

On the other hand, in supplying oil to the camshaft 12, the end portion 14a of the rocker arm 14 is connected to the base curve portion 12 of the cam surface 12A of the camshaft 12.
When the rocker shaft ₁₃ is in contact with the rocker shaft 13, the second through hole 25 provided in the rocker shaft 13 does not communicate with the second supply hole 22 of the rocker arm 14. No oil is supplied to the When the end portion 14a of the rocker arm 14 comes into contact with the cam surface 12A of the camshaft 12 and the lift valve curve portion _12A2 , that is, when the cam lift is reached, the rocker shaft 13
The second through hole 25 of the rocker arm 14 is
The oil from the oil passage 23 of the rocker shaft 13 flows through the second through hole 25 of the rocker shaft 13 and the second supply hole 22 of the rocker arm 14 to the cam surface 12A of the camshaft 12. is injected into
The camshaft 12 is supplied.

Therefore, while the application of hydraulic pressure to the intermediate member 15 is performed during a period other than the cam lift, lubricating oil is supplied to the camshaft 12.
This is performed only during the lift of the cam, and when the cam curve representing the lift of the cam surface 12A of the camshaft 12 is as shown in FIG. The supply period of lubricating oil to the camshaft 12 is intermittent, as shown by the shaded area in FIG. 3B, and the cam curve is obtained as shown by the shaded area in FIG. 3C. It will appear intermittently depending on the period of time.

In addition, the oil supply to the camshaft 12 is as follows:
Since oil is supplied from the oil passage 23, which is the same supply path as the oil supply for applying the working pressure to the intermediate member 15, when oil is supplied to the camshaft 12, the working pressure is applied to the intermediate member 15. However, as described above, since the oil supply period to the camshaft 12 is during the cam lift, at this time, the first member 17 in the intermediate member 15
The pressing part 17a presses the valve stem 7a and high pressure is applied to the hydraulic chamber 17b, and the oil reservoir chamber 1
Intermediate member 15 because pressure is not required for oil 8c
It does not cause any inconvenience to the operation. Further, proper lubrication of the camshaft 12 can be sufficiently achieved by intermittent supply of oil from the oil passage 23 within the rocker shaft 13.

In the above example, the beginning and end of the period for applying hydraulic pressure to the intermediate member 15 are made to coincide with the ends of the period for supplying lubricating oil to the camshaft 12, as shown in FIG. 3C. However, it does not necessarily have to be done this way, and the start and end of the application period of the hydraulic pressure to the intermediate member 15, as shown by the broken line in FIG. 3B, can be changed as shown in FIG. 3C. It is also possible to overlap both ends of the lubricating oil supply period to the camshaft 12.

Furthermore, although the intermediate member 15 is disposed at the end 14b of the rocker arm 14 on the valve stem 7a side, the intermediate member 15 is disposed at the end 14a of the rocker arm 14 on the camshaft 12 side and further at other parts. The present invention can also be applied in the same manner as described above.

(Effects of the Invention) As is clear from the above description, according to the engine valve train according to the present invention, oil is supplied to the intermediate member through the rocker shaft and the rocker arm during a period other than the cam lift time, and Since the camshaft can be supplied intermittently only when the cam is lifted, it is possible to properly supply lubricating oil to the camshaft without increasing the load on the oil supply source, and to reduce the amount of lubricating oil applied to intermediate members. Hydraulic pressure can be maintained sufficiently high.
Furthermore, there is no risk that the oil in the intermediate member will flow out through the first supply hole and the first through hole regardless of the stop position of the rocker arm. By being properly held, the valve clearance of the valve can be maintained in an appropriate state. Moreover, the engine valve train according to the present invention has the advantage of being able to obtain such excellent effects without requiring any special additional members in the oil supply system.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an outline of an example of an engine valve train according to the present invention, FIG. 2 is a side view showing an enlarged part of the example shown in FIG. FIG. 3 is a diagram for explaining the operation of the engine valve train according to the present invention. In the figure, 7 is an intake valve, 8 is an exhaust valve, 11
is the valve spring, 12 is the camshaft, 12
A is a cam surface, 13 is a rocker shaft, 14 is a rocker arm, 15 is an intermediate member, 21 is a first supply hole provided in the rocker arm 14, 22 is a second supply hole provided in the rocker arm 14, 2
3 is an oil passage provided in the rocker shaft 13, 24 is a first through hole provided in the rocker shaft 13, and 25 is a second through hole provided in the rocker shaft 13.

Claims (1)

[Scope of Claims] 1. A camshaft having a cam surface, an intake or exhaust valve, a rocker shaft fixed to a fixed part of the engine, and a rocker shaft that swings about the rocker shaft as a supporting shaft, The rocker arm is provided with a rocker arm that transmits the operation to the valve, and an intermediate member that is provided on the rocker arm and that adjusts the valve clearance of the valve using hydraulic pressure. A first supply hole and a second supply hole for supplying oil to the camshaft are formed, and an oil passage extending in the axial direction is provided in the rocker shaft, and the oil passage is opened in the radial direction from the oil passage and a second supply hole is formed for supplying oil to the camshaft. a first through hole that communicates with the first supply hole during a period other than the lift time, and a first through hole that opens in the radial direction from the oil passage,
A valve train for an engine, characterized in that a second through hole is formed that communicates with the second supply hole only during the cam lift.