JPH021460Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a bearing noise suppression device for an internal combustion engine, and particularly to a device that suppresses the occurrence of crankshaft impact noise by varying the clearance between the crankshaft journal and the bearing cap.

BACKGROUND TECHNOLOGY In an internal combustion engine, a bearing cap is attached to a bearing formed in a cylinder block of the engine, and the crankshaft is supported by the cap on the side opposite to the piston. Via the rod, the crankshaft is excited, which in turn excites the bearing cap. Here, since there is a clearance of several tens of microns between the crankshaft journal and the cap, the impact load is transmitted to the cap. Therefore, an impact sound (metal hitting sound) synchronized with the explosion is generated, and this impact sound is one of the main causes of engine noise. Conventionally, countermeasures against such metal hitting noises include (1) reducing the clearance between the crankshaft and the cap, and (2) increasing the bending rigidity of the crankshaft to reduce impact energy. However, method (1) above causes an increase in friction between the crankshaft and the cap, and method (2) increases the weight of the crankshaft, and both methods are unfavorable in terms of improving engine performance.

In order to reduce such impact noise (metal hammering noise), elastic material is interposed only in a predetermined range in the vertical direction of the parts of the cylinder block bulkhead and bearing cap where the bearing metal is crimped. (Japanese Unexamined Utility Model No. 57-28915), or one in which the skirt of the cylinder block and the bearing cap are connected via a cushioning material (Japanese Unexamined Patent Publication No. 55-82835)
However, since none of these methods forcefully change the clearance between the crankshaft and the bearing cap, they do not sufficiently suppress impact noise. In addition, it has poor heat resistance and oil resistance, and lacks reliability in its effectiveness.

Problems to be Solved by the Invention In this invention, by making the clearance between the crankshaft journal and the bearing cap variable, engine performance can be maintained at a good level while the impact noise (metal hammering noise) of the crankshaft can be generated. The purpose is to suppress

Means for Solving the Problems In order to solve these problems, a bearing cap was attached to the bearing part formed in the cylinder block of the engine, and the crankshaft was supported by the cap on the side opposite to the piston. In the configured internal combustion engine, a ceramic actuator is incorporated in the cap, and the ceramic actuator is operated only at the moment when the crankshaft vibrates the cap due to combustion pressure, thereby increasing the clearance between the cap and the crankshaft. A bearing noise suppression device for an internal combustion engine is provided, which is made smaller.

Embodiment FIGS. 1 and 2 show a first embodiment of the present invention. In the figure, 1 is a cylinder block, 2 is a cylinder, 3 is a piston, 4 is a connecting rod, 5 is a bearing part of the cylinder block,
6 is the crankshaft journal, 7 is the bearing cap,
Numeral 8 is a bolt for fastening the bearing cap to the bearing portion of the cylinder block. The bearing cap 7 supports the crankshaft journal 6 on the side opposite the piston 3.

In the present invention, a rectangular actuator mounting opening 11 is provided in the bearing cap 7, and a ceramic actuator 10 is inserted into the cylinder 2 within this opening 11.
fixedly arranged to expand in the axial direction of the This ceramic actuator 10 is connected through a lead wire 12 to a power source and a control device (not shown).

The timing for energizing the ceramic actuator 10 is as follows:
It is assumed that the explosion load of the engine is transmitted through the piston 3 and the connecting rod 4, and only at the moment when the crankshaft journal 6 excites the bearing cap 7. In order to determine the timing of energization, the top dead center signal of the piston, the cylinder pressure signal, the vibration detection signal of the bearing cap 7, and the clearance between the crankshaft journal 6 and the bearing cap 7 are used to determine the timing of energization. Using the detection signal etc. of
A computer (not shown) calculates the instant at which the crankshaft journal 6 vibrates the bearing cap 7, and energizes the ceramic actuator 10. As a result, ceramic actuator 1
0 expands in the axial direction of the cylinder 2 and pushes the bearing surface of the cap 7 from the broken line position to the solid line position in Fig. 2, and the clearance between the crankshaft journal 6 and the bearing cap 7 (C in Fig. 2) becomes smaller. The impact energy exerted by the crankshaft journal 6 on the bearing cap 7 is reduced.

Note that the clearance between the crankshaft journal 6 and the cap 7 decreases only at the moment when impact energy is applied, so it has almost no effect on the entire sliding friction of the crankshaft journal.

Figure 3 shows a second embodiment of the present invention.
In this case, a ceramic actuator 10 is placed under the bearing cap 7a, and a highly rigid frame member 13 is fastened together with the bearing cap 7a using cap bolts 8. When a voltage is applied, the ceramic actuator 10 expands in the axial direction of the cylinder 2, and the bearing cap 7a, which has relatively low rigidity compared to the frame material 13, is pushed upward, and the crankshaft journal 6 and the bearing cap are The clearance with 7 can be reduced.

Effects of the invention According to the invention, the clearance between the crankshaft journal and the bearing cap decreases at the moment when the crankshaft journal vibrates the bearing cap due to explosive combustion pressure, thereby reducing the impact exerted by the crankshaft journal on the bearing cap. The energy is reduced and thus the impact noise (metal banging noise) is suppressed.
Also, since the clearance reduction is instantaneous, it does not affect the overall sliding friction between the crankshaft journal and the bearing cap, and therefore does not reduce engine performance.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the first embodiment of the present invention, Fig. 2 is a diagram for explaining the operation of the same embodiment, and Fig. 3 is a diagram of the bearing cap portion showing the second embodiment of the present invention. be. 1...Cylinder block, 2...Cylinder, 3
...Piston, 4...Connecting rod, 5
... Cylinder block side bearing part, 6 ... Crankshaft journal, 7, 7a ... Bearing cap, 10
... Ceramic actuator, 11 ... Opening,
13...Frame material.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine, a bearing cap is attached to a bearing formed in a cylinder block of the engine, and the crankshaft is supported by the cap on the side opposite to the piston. Therefore, a bearing noise prevention device for an internal combustion engine is configured to operate the ceramic actuator to reduce the clearance between the cap and the crankshaft only at the moment when the crankshaft vibrates the cap.