JPS6326568Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fastening member such as a stud bolt used in an engine.

Conventionally, in a device that generates vibrations during operation, such as an engine, the natural frequency of a fastening member used in the device, such as a stud bolt, that fastens members at both ends, and the frequency of vibration generated by the device. It has been difficult to avoid resonance of the fastening member due to the coincidence of the numbers.

Therefore, the fastening members used in such devices must be designed with strength against resonance in addition to the originally required mechanical strength. This was one obstacle.

One way to solve this problem is to use a fastening member with steady-rest rubber baked into the side.
There is a method of forcibly suppressing the resonance of the fastening member by interposing the steady rest rubber between the fastening member and the surrounding members.

In this method, the fastening member itself can be designed without taking resonance into consideration. However, there were disadvantages in that it was difficult to assemble the fastening member with the steady-rest rubber baked into the side surface into the device, and the cost was high.

Therefore, an object of the present invention is to provide a fastening member that can reduce the weight of the entire device and is easy to assemble into the device.

A fastening member according to the present invention is a fastening member for fastening at least two members at both ends, and is characterized in that a viscoelastic member is attached to an intermediate shaft portion and a protective layer is provided to cover the viscoelastic member. do.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the crankcase of a motorcycle engine and its surrounding parts. The two-part crankcase 1 is mutually positioned by a pair of knock pins 2 and then fixed by a plurality of flange bolts 3. and is fastened together with the gasket 4.

The stud bolt 5 is used to fasten the crankcase 1 to the cylinder and cylinder head (not shown), and has a threaded portion 6 at one end and a female threaded portion 8 provided at the four corners of the cylinder mounting surface 7 of the crankcase 1. are screwed together.

The other end of the stud bolt 5 is provided with a threaded portion 9 into which a fastening nut (not shown) is screwed.

The outer diameter of the intermediate shaft portion 10 of the stud bolt 5 is machined to be smaller than the threaded portions 6 and 9, and the continuous portion between the threaded portions 6 and 9 and the intermediate shaft portion 10 forms a curved surface processed portion 11.

Note that the radial ball bearing 12 and the needle bearing 13 are fixed at predetermined positions in the crankcase 1, and are attached to a crankshaft (not shown), a transmission (not shown), etc. that are housed in the crankcase 1. This is to facilitate the rotation of the rotating member. In addition, the oil seal 14
is provided at a portion where the rotating member protrudes outside the crankcase 1 to maintain liquid tightness inside and outside the crankcase.

FIG. 2 shows an example in which the present invention is applied to such a stud bolt, and in this example, a viscoelastic member 15 such as rubber is attached to the intermediate shaft portion 10 over almost the entire length.
is covered. Further, a metal protective member 16 is fastened to cover the viscoelastic member 15 to form a protective layer. The outer diameter of the protective member 16 is set so that a sufficient gap is created between the protective member 16 and surrounding members when the stud bolt 5 is assembled to the engine and in the assembled state. The protective member 16 is formed by winding a band-shaped member spirally around the viscoelastic member 15 so that one side end of the band-shaped member overlaps the other side end.

By winding the metal band member in a spiral manner so that one side end of the band member wraps over the other side end, the rigidity of the fastening member as a whole is increased. increase Moreover, because of this configuration, the viscoelastic member 15 is completely covered with no gaps, and the viscoelastic member can be sufficiently protected. Further, by spirally winding the belt-like member on the viscoelastic member 15, the belt-like member can be wrapped around the viscoelastic member 15.
The viscoelastic member 15 can be easily brought into close contact with the viscoelastic member 15 with high precision, resulting in good workability.
It becomes possible to fully exhibit the vibration absorption effect associated with the shear strain.

As detailed above, in the fastening member according to the present invention, a viscoelastic member that damps resonance is attached to the intermediate shaft portion, so when designing the fastening member, it is necessary to take strength against resonance into consideration. There is no.

Furthermore, in the fastening member according to the present invention, the protective layer provided to cover the viscoelastic member not only protects the viscoelastic member, but also serves to increase the mechanical strength, particularly the rigidity, of the fastening member. ing.

Therefore, the fastening member according to the present invention has improved vibration resistance, has a thinner intermediate shaft portion, and is lighter in weight, resulting in a reduction in the weight of the entire device.

Furthermore, in the fastening member according to the present invention, there is a sufficient gap between the protective layer and the surrounding members when it is assembled into the device and in the assembled state, so that the assembly is smooth and easy. It can be done.

[Brief explanation of drawings]

Fig. 1 is a partially exploded perspective view of a motorcycle engine, Fig. 2a is a sectional view showing an embodiment of the present invention, Fig. 2b is a sectional view taken along line XX in Fig. 2a, and Fig. 2c is FIG. 2 is a side view of the embodiment shown in FIGS. 2a and 2b with the coating layer removed; Explanation of symbols of main parts, 5... Stud bolt, 6, 9... Threaded part, 10... Intermediate shaft part, 15
...Viscoelastic member, 16...Protection member.

Claims (1)

[Scope of utility model registration request] A fastening member for fastening at least two members, having a large-diameter threaded portion at both ends and a small-diameter intermediate shaft portion,
A viscoelastic member is applied over substantially the entire length of the intermediate shaft portion, and a metal protective layer is provided to cover the viscoelastic member, and the outer diameter of the protective layer is smaller than the outer diameter of the threaded portion. A fastening member characterized in that the layer is formed by winding a band-like member spirally around the viscoelastic member so that one side end of the band-like member overlaps the other side end.