JPH0220411Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields This invention relates to a valve device for an internal combustion engine.

(b) Prior Art An example of a conventional valve device is the one shown in Fig. 1 (``CA Engine Maintenance Manual 1981'' published by Nissan Motor Co., Ltd., October 1981). Since both the intake valve and exhaust valve operate in the same way, only the intake valve will be shown in the explanation. FIG. 1 shows the intake side, and the valve guide 101 is constructed separately from the cylinder head 103 and is fixed to the cylinder head 103 by press fitting. A guide hole 10 having a uniform inner diameter over the entire length is provided at the axial center of the valve guide 101.
5 is formed, and a solid valve stem 109 of an intake valve 107 is supported in the guide hole 105. Guide hole 105 and valve stem 109
A gap of 20 to 50 μm is formed between them, and the valve stem 109 is slidably guided in the guide hole 105. Then, the seat contact surface 113 of the umbrella portion 111 of the intake valve 107 contacts the valve seat 117 of the intake port 115, and the valve stem 10
One end of a rocker arm 121 is opposed to the head 119 of 9. The rocker arm 121 is swingably supported by a rocker shaft 123, and a cam 125 is in contact with the other end of the rocker arm 121. 127 is a valve spring, and 129 is a valve spring retainer.

During engine operation, the locker arm 121 is swung around the locker shaft 123 by the rotation of the cam 125, and when one end of the locker arm 121 presses the head 119 of the valve stem 109, the valve stem 109 is guided into the guide hole 105 of the valve guide 101. while sliding downward in Figure 1,
Intake port 115 is opened.

By the way, in such a conventional device, when one end of the locking arm 121 hits the head 119 of the valve stem 109, the direction of the impact force F of the one end of the locking arm 121 is aligned with the axis of the valve stem 109 as shown by the arrow in FIG. It has become deviated from its direction. Therefore, a component of the impact force F also acts in a direction perpendicular to the axis of the valve stem 109, and the second
Bending vibration of the valve stem 109 as shown by the thick line A in the figure is induced. When such vibrations are induced,
The axially intermediate portion of the guide hole 105 of the valve guide 101 is struck by the valve stem 109 .
Vibrations caused by this impact are transmitted to the rocker cover and cylinder block (not shown) via the cylinder head 103, and vibrations caused by the primary bending vibration of the valve stem 109 in the low frequency range (shaded area in Figure 3) in particular generate noise. This was becoming a problem.

On the other hand, the present applicant has previously proposed setting the rocker shaft 123 so that the direction of the impact force F of the rocker arm 121 coincides with the axis of the valve stem 109.

However, in this case, the lock shaft 12
3 has to be set upward in FIG. 1, which is not necessarily suitable when compactness must be taken into consideration.

In addition, since the valve stem 109 is solid,
The inertial mass is large, which is disadvantageous for increasing the rotation speed of the engine, and there is a problem in that the excitation force exerted on the cylinder head 103 side by the valve primary vibration of the valve stem 109 becomes large, which promotes vibration transmission.

(c) Purpose of the invention This invention was devised in view of the above-mentioned problems, and it is possible to reduce vibration and noise without compromising the compactness of the engine by simply improving the valve. The present invention provides a valve device that is advantageous for increasing engine speed.

(d) Structure of the invention In order to achieve this object, this invention provides a valve device having a valve stem slidably supported in the axial direction in a guide hole provided in a cylinder head of an internal combustion engine. A relief portion is provided between the upper and lower large diameter portions that substantially coincide with nodes of primary bending vibration of the valve stem, and at least a portion of the valve stem is formed hollow.

(e) Embodiment An embodiment of this invention will be described below in detail based on FIG.

FIG. 4 shows the intake side similarly to FIG. 1, and the valve guide 1, cylinder head 3, guide hole 5, intake valve 7, valve stem 9, umbrella portion 11, arranged in the same manner as in FIG. Seat surface 1
3, intake port 15, valve seat 17, head 19,
Rotsuka arm 21, Rotsuka shaft 23, cam 2
5, a valve spring 27 and a valve spring retainer 29 are shown.

The intake valve 7 is formed as shown in FIG. 5, and is provided with a relief portion 31 at an axially intermediate portion. The relief portion 31 is the upper and lower large diameter portions 9a and 9b.
The large diameter portions 9a and 9b substantially coincide with the nodes of the primary bending vibration caused by the impact when the intake valve 7 is opened. Both ends of the large diameter portions 9a, 9b are formed in a rounded shape to prevent galling against the valve guide 1. Furthermore, the valve stem 9 of the intake valve 7 is formed hollow to reduce weight. It is desirable to select the wall thickness t (mm) of the hollow valve stem 9 so that the resonant frequency f (Hz) does not decrease compared to the case where the valve stem 9 is solid. When the diameter is ≒7 mm, it is preferable to set t≒1.0 mm or more as shown in Fig. 6.

Next, the operation of the above embodiment will be explained.

When the engine is operating, the intake valve 7 is opened and the intake port 15 is opened in the same manner as in FIG. When the head 19 of the valve stem 9 is struck by one end of the rocker arm 21 when the intake valve 7 is opened, the valve stem 9 itself undergoes bending vibration as shown in FIG. 3, similar to the case shown in FIG. Excited. In this case, the amplitude of the valve stem 9 is
Due to the presence of the large-diameter portions 9a and 9b, the stiffness increases at the vibration nodes, and the stiffness decreases from the broken line A to the solid line B in FIG. Therefore, since the large diameter portions 9a and 9b substantially coincide with the nodes of the primary bending vibration caused by the impact when the intake valve 7 is opened, the valve stem 9 vibrates within the relief portion 31, and the valve guide It never hits 1. For this reason, vibrations caused by primary bending vibrations in the low frequency range, which are particularly problematic in terms of noise, are less likely to be transmitted to the lock cover and cylinder block (not shown). Next, even if the valve stem 9 slides due to the pressure of the rocker arm, the large diameter portions 9a and 9b are still vibration nodes of the valve stem 9, so vibrations are transmitted even when the intake valve 7 is not opened. can be prevented. Furthermore, since the valve stem 9 is hollow, the inertial mass is reduced, which is advantageous for increasing the engine speed. For the guide hole 5 of the valve guide 1,
Since the valve stem 9 slides on the large diameter parts 9a and 9b, the contact area is small and the contact resistance is small, so the balance between the guide hole 5 and the large diameter parts 9a and 9b can be made smaller than before. , vibrations caused by rattling can also be reduced. Large diameter part 9
Both ends a and 9b are formed in a rounded shape, and the large diameter portions 9a and 9b always slide against the guide hole 5 during sliding, so that galling against the guide hole 5 is less likely to occur and smooth sliding can be achieved. Can be done.

When bending vibration is excited in the valve stem 9, it appears that there is an input to the seat contact surface 13 due to the vibration of the umbrella portion 11, but in this case, since the intake valve 7 is in the opening operation, there is no input.

FIG. 7 shows an intake valve 7 according to another embodiment.
The large diameter portions 9a and 9b are solidly constructed as separate members, and are joined by flash butt welding to facilitate manufacturing. Since the other configurations are the same as those of the above embodiment, they are denoted by the same reference numerals.
The explanation will be omitted.

Note that the valve guide 1 can also be formed directly on the cylinder head 3 without forming it as a separate member from the cylinder head 3. Furthermore, it can also be applied to support the exhaust valve on the exhaust side. This idea can also be applied to swing arm types.

(f) Effects of the invention As is clear from the above, according to the configuration of this invention, even if the head of the valve stem is hit during the valve opening operation, bending force acts on the valve stem and bending vibration is induced. The relief part allows the relief part to escape from hitting the guide hole, reducing engine vibration and noise caused by primary bending vibration, which is a particular noise problem, and because the valve stem is hollow. , the inertial mass is small, and the engine can rotate at high speeds. Moreover, by providing a relief part in the valve stem, it is possible to escape from hitting the guide hole while the valve stem is sliding, and it is also possible to eliminate galling between the guide hole and the valve stem. be. Further, since no special machining is required on the guide hole side, it is easy to form the guide hole directly on the cylinder head. Furthermore, since the vibration amplitude of the valve stem is small, there is no need for a large relief part, and there is no need to change the arrangement of other parts, and the compactness of the engine is not compromised.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the conventional example, Fig. 2 is an explanatory view of the same operation, Fig. 3 is a bending vibration characteristic diagram of the valve stem, and Fig. 4 is a longitudinal sectional view of the embodiment of this invention.
FIG. 5 is a longitudinal sectional view of an intake valve, FIG. 6 is a graph showing changes in resonance frequency with respect to wall thickness, and FIG. 7 is a longitudinal sectional view of an intake valve according to another embodiment. 1... Valve guide, 3... Cylinder head,
5... Guide hole, 7... Intake valve, 9...
...Valve stem, 31... Relief part.

Claims (1)

[Scope of utility model registration request] In a valve device having a valve stem slidably supported in the axial direction in a guide hole provided in a cylinder head of an internal combustion engine, the valve stem has a large diameter at the top and bottom that substantially coincides with a node of primary bending vibration of the valve stem. A valve device characterized in that a relief portion is provided between the portions, and at least a portion of the valve stem is formed hollow.