JPS63117151A - Noise reduction structure for engine - Google Patents

Abstract

PURPOSE:To reduce noise due to vibration of a cylinder block, by forming a vibration damping gap between the inner wall face of a cylinder block and the outer wall face of a cylinder liner and filling said gap with lubricant. CONSTITUTION:An angular female screw 1b is etched in the inner circumferential face of a cylinder block 1 and screwed with a cylinder liner 5 etched with an angular male screw 1a. A piston 8 is contained in the cylinder liner 5. Spiral vibration damping spaces C are formed between respective crest M and root V sections of the female screw 1b and the male screw 5a and filled with lubricant O. Consequently, vibration and deformation of the cylinder liner 5 are damped, resulting in reduction of noise.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a noise reduction structure in an engine such as a diesel engine or a gasoline engine, and more specifically relates to a structure for reducing noise in an engine such as a diesel engine or a gasoline engine. The present invention relates to a noise reduction structure that reduces engine noise by improving the structure.

(Prior Art) Conventionally, as shown in FIG. 7, in the fitting structure between a cylinder block and a cylinder liner, a cylinder liner 22 is fitted onto the inner wall surface of a cylinder block 21, and a water jacket 23 is provided between the two. There are two types: a wet liner type in which the cylinder liner 22 is fitted and fixed to the inner wall surface of the cylinder block 24 on which a water jacket 24a is formed as shown in FIG.

(Problem to be Solved by the Invention) However, in the former wet liner type engine, the outer peripheral surface of the cylinder liner 22 serves as the cooling water, and the shape of the water jacket 23 or the physical properties of the water may cause the piston 8 to There is a problem in that the effect of actively damping vibrations of the cylinder liner 22 due to slump force and combustion chamber pressure cannot be expected.

Furthermore, in the latter dry liner type engine, the outer peripheral surface of the cylinder liner 22 is in contact with the inner wall surface of the cylinder block 24, and the water jacket 24a is formed within the cylinder block 24, so that the above-mentioned sea urchin However, there was a problem in that it could only be expected to be as effective as the triner type.

Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes fitting a cylindrical cylinder liner to the cylindrical inner wall surface of a cylinder block forming a water jacket, In a dry liner type engine in which a piston is reciprocatably housed inside the cylinder liner, lubricating oil pumped from an oil pump is used between the inner wall surface of the cylinder block and the outer wall surface of the cylinder liner. In this method, a deformable vibration damping gap is formed to damp vibration and deformation of the cylinder liner due to excitation forces such as piston slump force and combustion chamber pressure.

(Function) When the engine is operated, the cylinder liner is vibrated by the slap force of the piston or the combustion chamber pressure, and this vibration deforms the vibration damping gap, and the vibration energy is absorbed by the lubricating oil flowing inside the gap. As a result, vibration of the cylinder block is reduced, and engine noise is reduced.

(Example) Hereinafter, an example in which the present invention is embodied in a gasoline engine will be described based on FIGS. 1 to 3.

As shown in FIG. 3, a cylinder head 2, also equipped with a water jacket 2a, is fixed to the upper surface of the cylinder block 1, which is equipped with a water jacket 1a. ) is provided. Further, an oil pan 4 is bonded and fixed to the lower end opening surface of the cylinder block 1. A square female thread 1b is formed on the inner circumferential surface of the cylinder block 1, and a cylinder liner 5 having a square male thread 5a is screwed into the female thread 1b. A piston 8 connected to a crankshaft 6 and a connecting rod 7 is accommodated within the cylinder liner 5 .

A flange portion 5 is provided on the outer peripheral portion of the upper end of the cylinder liner 5.
b is formed, and is engaged with an annular engagement step portion 1c formed on the inner peripheral portion of the upper end of the cylinder block 1. By clamping and fixing the flange portion 5b between the engagement step portion 1c and the cylinder head 2, the upper end portion of the cylinder liner 5 is held at a predetermined position. The lower end outer circumferential surface 5c of the cylinder liner 5 is fitted and fixed to the lower end inner circumferential surface 1d of the cylinder block 1, and its position is regulated.

Moreover, the respective peaks M and troughs V of the female thread 1b of the cylinder block 1 and the male thread 5a of the cylinder liner 5.
A deformable, overall spiral vibration damping gap C is formed between the cylinder liner 5 and the cylinder liner 5 to damp vibration and deformation of the cylinder liner 5 due to the slap force of the piston 8 or combustion chamber pressure using lubricating oil 0. . The slit G in the side surfaces of the crests M of the two screws lb and 5a that are in sliding contact with each other is the screw lb.

5a are in sliding contact with the necessary dimensional tolerance for screwing together, and the lubricating oil 0 in the gap C provides sufficient lubrication, and the gap gc is deformed to allow the cylinder liner 5 to move outward. It allows for deformation due to vibration.

Lubricating oil O is supplied to the upper end opening of the imaging damping gap C from an oil passage 1e provided at the upper end of the cylinder block 1 through an oil supply port 1f. The oil passage 1e
The lubricating oil 0 is supplied to the oil pan 4 by an oil pump 9 disposed within the oil pan 4, as shown in FIG. Note that 10 is an oil filter, and an oil cooler (path shown) may be provided after this.

At the lower end of the cylinder block 1, there is an oil drain port having a passage cross-sectional area smaller than that of the cavity C, through which the lubricating oil that has flowed down to the lower end closed part of the vibration damping cavity C drops into the oil pan 4 and is returned to the oil pan 4. 1g is formed. The cross-sectional areas of the gap C and the oil drain port 1g are appropriately set so that the gap C is always filled with lubricating oil 0 during engine operation.

Next, the operation of the engine configured as described above will be explained.

In the operating state of the engine, the piston 8 reciprocates in the vertical direction, and the oil pump 9 is operated to pump up the lubricating oil O in the oil pan 4, and the oil filter 1
0 and an oil cooler (path shown) to the oil passage 1e, and further supplied to the air 8iC through the oil filler port 1f.

This lubricating oil O circulates within the spiral vibration damping gap C and cools the cylinder liner 5 while cooling the oil drain port 1g at the lowest end.
It is dripped into the oil pan 4 from there.

When the slap force of the piston 8 or the combustion chamber pressure acts on the cylinder liner 5 during operation of the engine, the cylinder liner 5 is pushed outward and deformed as shown in FIG. Due to this deformation, the void C is deformed, and the void C
Lubricating oil 0 filled with the oil filler port 1f or oil drain port 1
At this time, the vibration energy of the cylinder liner 5 is attenuated by the flow resistance due to the viscosity peculiar to lubricating oil, and the cylinder block 1 and oil pan 4
vibrations are also damped, reducing engine noise.

Furthermore, since the present invention utilizes the lubricating oil originally required by the engine, there is no need to use a special vibration absorbing member made of resin, and from this point of view, reliability can be improved.

Note that this invention can also be embodied in the following embodiments.

(1) As shown in FIG. 4, the screws 1b and 5a between the cylinder block 1 and cylinder liner 5 are trapezoidal screws. In this alternative example, the screw machining is simpler than in the previous embodiment, and since the crests M and the troughs (2) are tapered fit, the vibration damping effect is improved.

(2) As shown in FIG. 5, the cylinder block 1 is simply formed with a cylindrical inner circumferential surface 1h, and the outer circumferential surface of the cylinder liner 5 is formed with a large number of annular protrusions 5d in the vertical direction. A vibration damping gap C that exhibits a labyrinth effect is formed between the protrusion and the inner circumferential surface of the cylinder block 1. In this embodiment, the vibration of the cylinder liner 5 is also damped by the lubricating oil filled in the gap C. can be attenuated.

(3) As shown in FIG. 6, splines 1t+5e are formed on the cylinder block 1 and cylinder liner 5, and vibration damping gaps C are formed between the peaks M and troughs V of both splines.
to form.

Effects of the Invention As detailed above, the present invention reduces the vibrations and deformations that act on the cylinder liner due to m-vibration forces such as the slap force of the piston or the pressure in the combustion chamber during engine operation by reducing the lubricating oil flowing in the vibration damping gap. It is possible to dampen noise due to the physical properties of the cylinder and the deformation of the gap, thereby reducing noise caused by vibrations of the cylinder block and oil pan. Furthermore, by utilizing the lubricating oil required by the engine, there is no need to use a vibration damping member such as a special resin, which has the effect of improving reliability.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of the main part in the engine stopped state, showing one embodiment of the noise reduction structure in the engine engine of the present invention, FIG. 2 is an enlarged cross-sectional view of the main part in the engine operating state, and FIG. The figure is a vertical cross-sectional view of the central part of the engine, Figures 4 to 6.
Each figure is a cross-sectional view of only the main part showing another example of the present invention, and FIGS. 7 and 8 are cross-sectional views showing a conventional example, respectively. Cylinder block 1, female thread lb, oil filler port 1f. Oil drain port 1g, inner peripheral surface 1h, spline 11, cylinder liner 5, male thread 5a, annular protrusion 5d, spline 5e
, vibration damping gap C1 screw (spline) peak M1 valley ■.

Claims (1)

[Claims] 1. A dry liner in which a cylindrical cylinder liner is fitted onto the cylindrical inner wall surface of a cylinder block forming a water jacket, and a piston is reciprocatably housed inside the cylinder liner. In this type of engine, lubricating oil is pumped from an oil pump between the inner wall surface of the cylinder block and the outer wall surface of the cylinder liner, and the cylinder is moved by the excitation force such as the slap force of the piston or the pressure in the combustion chamber. A noise reduction structure for engines that has a deformable vibration damping cavity that dampens liner vibrations. 2. An angular or trapezoidal female thread is formed on the inner wall surface of the cylinder block, and an angular or trapezoidal male thread that is screwed into the female thread is formed on the outer wall surface of the cylinder liner. The noise reduction structure for an engine according to claim 1, wherein a vibration damping gap is formed between the crest and the trough of the screw. 3. According to claim 1, splines are formed in the vertical direction on the inner wall surface of the cylinder block and the outer wall surface of the cylinder liner, and vibration damping gaps are formed between the peaks and valleys of the splines. Noise reduction structure in the engine described.