JPS6237924Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a valve operating mechanism for an internal combustion engine, and particularly relates to a valve operating mechanism having a rocker arm that is rotatably held.

(Prior art) In general, in internal combustion engines, it is necessary to provide valve clearance, mainly taking into account the difference between thermal expansion of the cylinder head and expansion of the valve mechanism, and this clearance must be properly adjusted. , Noise was generated while the engine was running, and horsepower loss occurred due to raw gas blowing through. For this reason, in the prior art, a lash adjuster is arranged between the members of the valve train to keep the valve clearance at zero during the operation of the valve train, and to prevent dimensional changes due to differences in thermal expansion and wear. It is being considered that the valve clearance does not need to be adjusted in order to absorb dimensional changes and prevent the generation of noise.

(Problem that the invention seeks to solve) However, when inserting a lash adjuster into an existing valve mechanism, it is necessary to change the layout, or in particular, an overhead cam (where the camshaft shaft is located in the cylinder head) is required. With the OHC) type, the valve mechanism is short, so it is necessary not only to change the layout but also to downsize the lash adjuster itself. However, in order to ensure that this latch adjuster has the strength to withstand the biasing force received from the valve spring of the valve train, it is necessary to reduce the stress caused by the biasing force to an extent that the body can withstand by increasing its body size. Inevitable. For this reason, the current lash adjuster,
The drawback is that some OHC types cannot be made small enough to fit into existing valve train mechanisms, and a lash adjuster cannot be inserted without changing the existing layout.

Therefore, an object of the present invention is to enable a latch adjuster to be inserted into an existing valve train having a rotatably held rocker arm without requiring any layout changes.

(Means for Solving the Problems) The technical measures taken to achieve the above object include a first rocker arm member having one end that engages with a camshaft and a first rocker arm member that has the other end that engages with a valve stem. Both rocker arm members are held by a rocker arm shaft, and a sealed latch adjuster is sandwiched between both rocker arms.

(Function) With the above means, the difference between the thermal expansion of the cylinder head and the expansion of the valve mechanism can be effectively absorbed by the sealed lash adjuster disposed between both rocker arms.

(Example) An example of an OHC type valve train according to the present invention will be described below with reference to FIG. In the drawing, a cylinder 11 is disposed inside a cylinder block 10, and a piston 12 reciprocates inside the cylinder 11.
A combustion chamber 14 is formed above the piston 12 by a cylinder head 13 forming the upper end of the cylinder 11 . Communication between the combustion chamber 14 and the cylinder head port 15 is provided by an engine valve 16.
Opening/closing is controlled by Cylinder head 1
A valve spring 20 is disposed between a spring seat 17 formed on the upper end surface of the valve stem 18 and a spring retainer 19 fixed to the upper part of the valve stem 18. It is always urged upward in the figure so that it is seated at 21.

The first rocker arm member 22 and the second rocker arm member 23 both have a shaft hole, and the rocker arm shaft 25 inserted into the shaft hole overlaps the shaft hole portions and holds the rocker arm member in the internal combustion engine body. be done. The first rocker arm member 22 has a convex lower end portion 22b that engages with the top of the valve stem 18. The second rocker arm member 23 has its lower end convex surface portion 23b in contact with the camshaft 24. Further, the first and second rocker arm members 22 and 23 have hemispherical concave portions 22 on their upper sides.
c, 23c. Incidentally, the hemispherical concave surfaces 22c, 23c of both rocker arm members 22, 23 are provided with openings 22a, 23a for supplying lubricant.
A hemispherical convex portion 47a is provided on the fulcrum 47, and a hemispherical convex portion 3 is provided on the cylindrical bottom portion of the adjuster body 31.
1e, a sealed latch adjuster 30 having a
placed between. This lash adjuster 30 has both hemispherical convex portions 47a and 31e.
engages with the hemispherical concave surfaces 22e and 23c of both rocker arm members 22 and 23, and is held between both rocker arm members 22 and 23.

Next, the lash adjuster 30 will be explained based on FIG. 2. The adjuster body 31 has a shaft hole 31a with an open upper end, and a hollow plunger 32 reciprocates in the shaft hole 31a. An annular oil return groove 33 having a concave spherical cross section is formed on the outer periphery of the plunger 32 at approximately the center in the longitudinal direction, and an oil return hole 34 communicating with the oil return groove 33 is further formed. A reservoir 35 is formed inside the plunger 32, and a pressure chamber 36 is formed between the bottom wall of the plunger 32 and the bottom wall 31b of the adjuster body 31. asiya star body 31
The shoulder portion 31c formed on the plunger 32
The downward movement of is regulated. In other words, the shoulder portion 31c functions as a stopper. An oil passage 37 is formed in the center of the bottom wall 32a of the plunger 32, and a well-known ball check valve 38 is disposed in the oil passage 37 on the pressure chamber 36 side. The ball check valve 38 is always urged in the closing direction, that is, in the direction of contacting the valve seat surface 41, by the other end of a spring 40, one end of which is supported by the retainer 39. A plunger return spring 42 stronger than the spring 40 is provided in the pressure chamber 36.
is arranged, and the retainer 3 is held by the spring 42.
9, the plunger 32 connects to the adjuster body 3.
1 is constantly biased upward.

A retractable rubber bag 43 is disposed in the reservoir 35, and its upper fixed part 43a is fitted into an annular large diameter groove 32b formed on the upper inner circumference of the plunger 32 and inserted into the inner circumference of the fixed part 43a. The rubber bag 43 is connected to the plunger 3 by the metal ring 44
It is fixed at 2. The elastic part 43b of the rubber bag 43 functions to absorb oil fluctuations in the reservoir 35, and its outer surface is always in contact with the oil surface in the reservoir 35, and its inner surface is always in communication with the atmosphere, as will be described later. are doing. An annular groove 32c is formed on the upper outer periphery of the oil return groove 33 of the plunger 32, and a seal ring 45 made of rubber is fitted into the groove 32c to form an adjuster seal. The adjuster seal 45 seals the internal oil. A leak clearance 46 is provided between the inner peripheral surface of the adjuster body 31 and the outer peripheral surface of the plunger 32, and leaked oil flows from the pressure chamber 36 into the reservoir 35 via the leak clearance 46. Also,
An atmospheric passage 4 is provided in the body portion 47b of the Fulcrum 47.
8 is formed, and the inside of the rubber bag 43 is always in communication with the atmosphere via the atmospheric passage 48. Furthermore,
A sleeve 49 integrally formed with the Fulcrum 47 is inserted between the adjuster body 31 and the plunger 32 below the Fulcrum 47. Furthermore,
As described above, the fulcrum 47 is formed with a hemispherical convex portion 47a, and the cylindrical bottom of the adjuster body 31 is formed with a hemispherical convex portion 31e.

The operation of the above configuration will now be explained.
First and second Rocker arm members 2 rotatably held by a Rocker arm shaft 25
2 and 23 sandwich the latch adjuster 30 between them, the first rocker arm member 22 biases the latch adjuster 30 toward the second rocker arm member 23 due to the biasing force of the valve spring 20. As a result, the second rocker arm member 23 comes into contact with the cam surface 24a of the camshaft 24. In this way, the first and second rocker arm members 22 and 23 effectively operate as one unit, and furthermore, since fluctuations in valve clearance can be absorbed by changing the overall length of the lash adjuster 30, the valve clearance can be reduced. Eliminates the need for adjustment. Therefore, when the engine starts, the camshaft 24 is rotated by the crankshaft.
One end 23b of the second rocker arm member 23 is pushed upward in the figure using the rocker arm shaft 25 as a fulcrum, and at the same time the first rocker arm member 22 is pushed downward in the figure. As a result, the valve stem 18 moves downward in the drawing against the urging force of the valve spring 20, and the engine valve 16 opens.

Next, when the camshaft 24 further rotates, the valve stem 18 moves upward in the drawing due to the biasing force of the valve spring 20, and the engine valve 16 closes, and this process is repeated as the camshaft 24 rotates thereafter.

(Effects of the invention) As described above, since the rocker arm is made of two members and the sealed lash adjuster is sandwiched between them, the lash adjuster can be inserted without changing the layout of the existing valve mechanism.
Furthermore, since it is a sealed type latch adjuster, it only needs to be clamped between both rocker arm members, and there is no need to route the latch adjuster's guide member or oil passage, which is required in conventional oil-supplied latch adjusters. have an effect. Therefore, there is an effect that precision is not required for machining the outer periphery of the lash adjuster body.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of an OHC type valve mechanism according to the present invention, and FIG. 2 is a sectional view of a lash adjuster attached to the valve mechanism. 18: valve stem, 20: valve spring, 22: first rocker arm member, 23: second rocker arm member, 24: camshaft,
25: Locker armshaft, 30: Latch adjuster.

Claims (1)

[Scope of utility model registration request] A rocker arm rotatably held on the internal combustion engine body by a rocker arm shaft, a camshaft disposed to engage with one end of the rocker arm and driven by the crankshaft to rotate and swing the rocker arm, and a camshaft at the other end of the rocker arm. In a valve operating mechanism including a valve stem disposed to engage with each other, and a valve spring that biases the valve stem toward the rocker arm, the rocker arm may be engaged with the first end having the other end with which the valve stem engages. a second rocker arm member having the one end that is engaged with the camshaft; both rocker arm members are held by the rocker arm shaft, and a sealed latch adjuster is provided between the rocker arm members. A valve mechanism in which the star is held between the valves.