JPH0364655A - Rudder frame for cylinder body - Google Patents

Abstract

PURPOSE:To improve rigidity of a cross member and to reduce the generation of vibration and noise by a method wherein side members are intercoupled by means of a plurality of cross member with an axial distance therebetween, and the cross memers are intercoupled through a reinforcing member positioned along the side members. CONSTITUTION:A rudder frame 1 is formed such that the front and rear ends of a plurality of side members 2 positioned with a specified distance therebetween are intercoupled through first cross members 3, and the side members 2 between the first cross members 3 are intercoupled through second cross members 4 positioned at equal intervals. The cross members 3 and 4 on the cylinder body rear wall 10 side are intercoupled through a reinforcing member 11 positioned along the direction of the side member 2. The reinforcing member 11 is formed such that longitudinal beams 12 having length long enough to span between the cross members 3 and 4 and lateral beams 13 shorter than the cross embers 3 and 4 are intercoupled. A semicircular bearing surface 5 is formed in the upper surface of each of the cross members 3 and 4, i.e. the central part of a mounting surface where the cross members are mounted to a cylinder body 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ladder frame of a cylinder body that rotatably supports a crank journal in cooperation with the cylinder body.

[Prior Art] A cylinder body/skirt opening/closing mode is a vibration mode that particularly affects the noise characteristics of an engine. Vibration in this mode is mainly caused by the excitation force caused by combustion passing through the transmission path from piston a to connecting rod b to bearing part d that supports crankshaft C to cylinder body/skirt part e, as shown in Figure 3. Follow. That is, in response to the combustion gas force, the crankshaft C is microscopically bent to generate a force that tilts the bearing part d, and the bearing forcibly vibrates the skirt part e, causing it to vibrate.

Therefore, recently, as a countermeasure for the vibration transmission system in short-skirt engines, proposals have been developed for a ladder frame that is connected to the lower end of the cylinder block and has an integral bearing cap (Japanese Utility Model Publication No. 105741/1983, etc.). , the front-back vibration of the bearing that supports the crankshaft is suppressed to reduce skirt opening/closing vibration, and at the same time, the torsional and left-right bending rigidity of the cylinder block is also improved.

[Problems to be Solved by the Invention] However, even if this type of ladder frame is proposed, if the excitation force of the vibration propagated from the bearing section is large compared to its rigidity, the ladder frame will cause vibration to the cylinder body. There is a problem in that it propagates and generates noise.

Figure 4 shows an analysis of the vibration of the cylinder body to which the ladder frame is attached, and shows that the rear wall of the cylinder body is damaged due to insufficient rigidity of the ladder frame in the axial direction of the crankshaft.
This indicates that the crankshaft is violently vibrating back and forth in the axial direction.

In other words, since the ladder frame integrally has a bearing surface that rotationally supports the crank journal, if its rigidity is low, vibrations propagated from the crank journal will be propagated as is, causing the cross member to vibrate in the longitudinal direction of the crankshaft. This was pointed out as an issue because it generates noise from the cylinder body.

An object of the present invention is to increase the structural strength of a ladder frame against propagated vibrations, suppress vibrations of the ladder frame, and reduce noise of a cylinder body.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of cross members each having a bearing surface for a crank journal formed on the upper surface, and the side members are integrally spaced apart from each other in the axial direction. The cross members are connected to each other by reinforcing members in the direction of the side members.

[When the cross members are connected to each other with a reinforcing member in the direction along the acting side member direction, the structural strength of the side member and the cross member is increased. As a result, the rigidity of the side member is substantially increased against the vibration propagated from the crank journal in the direction along the side member, and the vibration of the cross member and the side member is suppressed.

[Embodiment] A preferred embodiment of the present invention will be described below based on the accompanying drawings.

As shown in FIG. 1, the ladder frame l integrally connects the front and rear ends of two side members 2 having a constant interval with each other by first cross members 3 of equal length. The side members 2 between the cross members 2 are integrally connected by second cross members 4 at equal intervals. These first. The second cross members 3 and 4 have a semicircular bearing surface 5 formed at the center of the upper surface thereof, that is, the mounting surface to the cylinder body 6. In other words, each bearing surface 5 and each bearing surface 7 of the cylinder body 6 connect the crankshaft (
A bearing 8 is configured to rotationally support a crank journal (not shown).

Now, the purpose of this invention is to
The purpose is to increase the overall structural strength after the skirt seating surface 9 of the skirt is connected to the ladder frame 1, and to print vibrations of the cylinder body 6.

Therefore, in this embodiment, in order to suppress the front t & torsional vibration of the cylinder body f & ulo especially in the crankshaft direction, the cylinder body rear ? The rigidity of the cross member 3.4 of 10 riri is substantially improved and vibration damped.

Further, in this embodiment, from the viewpoint of productivity and cost, the rigidity of the cross members 3 and 4 is improved without changing the shapes of the cross members 3 and 4. For this purpose, the first
As shown in the figure, adjacent first. The second cross members 3 and 4 are connected to each other by a reinforcing member 11 extending in the direction of the side member 2.

The reinforcing member 11 is the first. A vertical beam 12 with a length that spans the second cross member 2゜3 and a horizontal beam 13 whose length is shorter than the cross members 2 and 3 are integrally connected, and furthermore, these vertical beams 12 and A pillar-shaped gilt boss portion 15 having a bolt insertion hole 14 is integrally formed at the connection portion with the cross beam member 13.

In other words, the reinforcing member 11 is formed into a rectangular shape with the bolt boss portions 15 arranged at the four corners. On the other hand, the first. The second cross member 3.4 has the above-mentioned cross beam member 13 in its longitudinal direction.
Screw holes 16 are formed at the same hole pitch as the bolt insertion holes 14° 14 at both ends. Note that the first thing. The formation position of the screw holes 16.16 with respect to the second cross members 3, 4 is the same as that of the first. The positions are distributed to the left and right with the longitudinal center of the second cross members 3 and 4 as a reference.

Therefore, each bolt insertion hole 14 of the reinforcing member 11 is inserted into the first. Each screw hole 16, 16 of the second cross member 3, 4
When the fastening bolts 17 are screwed into the bolt insertion holes 14, 14 and the screw holes 16.16, the first cross member 3. The rectangular body formed by the second cross member 4 and the side members 2 is divided into three rectangular bodies, and each of the divided rectangular bodies comes to share the excitation force of the transmitted @@ motion. As a result, 1. second cross member 3,
4. The overall structural strength, in other words, the overall rigidity after the first cross member 3, second cross member 4, and side member 2 are joined, can be increased without increasing the rigidity of the cross member 4 itself.

FIG. 3 shows actual noise data when the reinforcing member 13 of this embodiment is attached to the first and second cross members 3 and 4.

As is clear from the figure, the common frequency of the vehicle is l~2kHz.
It can be confirmed that the noise level is reduced and that the reinforcing member 13 contributes to the noise level reduction.

In addition, in the description of the embodiment, the reinforcing member 13 is referred to as the first reinforcing member 13. Although we have explained how to bolt the reinforcing member 13 to the second cross member 3.4, even if this reinforcing member 13 is bolted to the skirt seating surface 9 together with the first and second cross members 3 and 4, it will not lie horizontally. The reinforcing member 13 may be formed as a single member that is stretched over the first and second cross members 3 and 4 and fixed with bolts, as long as the necessary structural strength against the above-mentioned vibrations can be obtained. Further, the reinforcing member 13 is attached to the rear wall III! of the cylinder body 6! The attachment is not limited to the first and second cross members 3 and 4 of the crankshaft, but rather the first cross member, which has low rigidity against vibration propagation in the axial direction of the crankshaft. It is natural to attach it to the second cross members 3, 4 so as to substantially increase its stiffness. Therefore, the reinforcing member 13 is formed into a ladder shape when the entire structure is reinforced to further improve the rigidity.

[Effects of the Invention] As is clear from the above explanation, the present invention exhibits the following excellent effects.

The side members are integrally connected to each other at intervals in the axial direction using a plurality of cross members each having a bearing surface for a crank journal formed on the upper surface, and the cross members are connected to each other by a reinforcing member in the direction along the side members. Therefore, the rigidity of the cross member is improved, vibration propagation to the cylinder body is suppressed, and noise levels can be reduced.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a preferred embodiment of the present invention, and Fig. 2 shows a comparison of noise data of a cylinder body when a conventional ladder frame is installed and a cylinder body when a lug frame is installed with a reinforcing member. The performance chart, FIG. 3 is a schematic diagram showing the vibration propagation path, and FIG. 4 is an analytical diagram showing the vibration state of the cylinder body. In the figure, 2 is a side member, 3.4 is a cross member, 5 is a bearing surface, and I3 is a reinforcing member.

Claims (1)

[Claims] 1. A reinforcing member that integrally connects the side members at intervals in the axial direction with a plurality of cross members each having a bearing surface for a crank journal formed on the upper surface thereof, and reinforcing the cross members in the direction along the side members. A ladder frame with a cylinder body that is characterized by being connected by.