JPH0346271Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] This invention relates to a vibration isolation structure for suppressing vibration isolation of a rear end plate of a vehicle engine. [Prior Art] Usually, the lower part of the rear end plate overhangs the cylinder block and closes the lower opening of the clutch housing. [Problems to be Solved by the Invention] The tip of the rear end cover that closes the open portion of the lower part of the clutch housing becomes a so-called free end. Therefore, when the rear end plate resonates during engine operation, the free end portion vibrates violently, and this vibration contributes to noise. In order to reduce such vibrations, countermeasures are generally taken such as increasing the thickness of the rear end plate or using a double steel plate structure. However, increasing the plate thickness or creating a double structure increases the weight and makes processing difficult. The technical objective of this invention is to provide a vibration-isolating structure for a rear end plate that exhibits a vibration-isolating effect that is superior to the conventional one even when using vibration-isolating weights of the same mass. [Means for Solving the Problems] In order to solve the above problems, the vibration isolation structure of the rear end plate according to the present invention is configured as follows. That is, in a structure in which the lower part of the rear end plate assembled interposed between the cylinder block and the clutch housing of a vehicle engine protrudes from the cylinder block and closes the open part of the lower part of the clutch housing, A substantially cylindrical anti-vibration weight is fixed to the rear end plate of the rear end plate via a plurality of legs formed integrally with the anti-vibration weight. Moreover, this vibration-isolating weight includes a portion having a larger cross-sectional area than the area surrounded by the contact portion of each leg with respect to the rear end plate. [Function] According to the above configuration, the vibration of the rear end plate that protrudes from the cylinder block during engine operation is suppressed by the vibration isolating weight. Moreover, since the vibration isolating weight is fixed to the rear end plate via a plurality of legs, the rear end plate is restrained due to the fixation of the weight, compared to the case where the entire end face of the weight is brought into direct surface contact. The range is small. Further, the large diameter portion of the vibration isolating weight has a cross-sectional area larger than the area of the portion surrounded by the contact portion of each leg with respect to the rear end plate. For these reasons, compared to the case where weights of the same mass and height are used, the bending rigidity of the rear end plate changes less, and its natural frequency becomes lower. [Example] Hereinafter, an example of the present invention will be described based on the drawings. First Embodiment In FIGS. 1 and 2, a rear end plate 3 of a vehicle engine is assembled so as to be interposed between the rear end surface of a cylinder block 1 and the front end surface of a clutch housing 2. Note that an oil pan 5 is attached to the lower surface of the cylinder block 1. As is clear from FIG. 1, the lower portion of the rear end plate 3 protrudes downward from the cylinder block 1 and closes the lower open portion of the front end surface of the clutch housing 2. That is, only one side of the lower part of the rear end plate 3 is fixed to the clutch housing 2 side. A vibration isolating weight 4 is fixed to a portion of the rear end plate 3 projecting from the cylinder block 1. This anti-vibration weight 4
is formed into a substantially cylindrical shape, and is fixed to the rear end plate 3 by four legs 4a integrally formed therewith. A portion 1 surrounded by the contact portion of each leg 4a with the rear end plate 3
2 is rectangular as shown in FIG. Further, the vibration isolating weight 4 has a cross-sectional area larger than the area of the portion 12 surrounded by the contact portion of each leg 4a. FIG. 3 shows a conventional general vibration isolation structure of a rear end plate. In FIG. 3, the vibration isolating weight 7 has a simple cylindrical shape and is fixed to the rear end plate 3 at a contact surface 8. As shown in FIG. Now, the anti-vibration weight 4 shown in FIGS. 1 and 2 and the anti-vibration weight 7 shown in FIG. 3 have the same mass and the same height from the rear end plate 3. If there is, the area of the portion 12 surrounded by the legs 4a of the vibration isolating weight 4 of this embodiment will naturally be smaller than the area of the contact surface 8 of the weight 7 shown in FIG. Further, if the area of the portion 12 surrounded by each leg 4a and the contact surface 8 of the weight 7 is made the same, the height of the vibration isolating weight 4 will be smaller than that of the weight 7. Note that the anti-vibration weight 4 of this embodiment has the above-mentioned legs 4a.
Because it is fixed to the rear end plate 3,
Compared to the case where the entire end surface of the weight 7 is fixed in contact with the rear end plate 3 as shown in Fig. 3, the restraint range of the rear end plate 3 due to the fixation of the weight is small, and the effect on the bending rigidity is small. . By the way, as shown in Fig. 4, a predetermined elastic plate A is supported at both ends thereof, and the distance between the two support points is l, and the elastic plate A is supported at positions l1 and l2 from both the support points. When a load m is applied, the spring constant k of the elastic plate A is k=3EIl/l1 ² l2 ² . Here, EI is the bending stiffness of the plate. The above equation applies when the load m is a point load, but when the load m has a width, as the width becomes wider, l1 and l2, which can be freely bent, decrease and the spring constant k increases. . On the other hand, the natural frequency f of the elastic plate A is f=1/2π√. Therefore, if the load m is the same, the natural frequency f increases as the spring constant k becomes larger, that is, as the width of the load m becomes wider. In other words, the smaller the width of the load m, the lower the natural frequency f. When the above is replaced with the relationship between the rear end plate 3 and the anti-vibration weight 4, the smaller the contact area of the anti-vibration weight 4 with the rear end plate 3, the lower the natural frequency of the rear end plate 3 will be. In this embodiment, each leg 4
l ₁ and l ₂ shown in FIG. 4 change depending on the interval a. For example, if the spacing between the legs 4a is large, l ₁ and l ₂ will be small, and conversely, if the spacing between the legs 4a is small, l ₁ and l ₂ will be large. Therefore, by reducing the area of the portion 12 surrounded by each leg 4a, the natural frequency of the rear end plate 3 becomes lower than that of a weight having the same mass and height. As described above, according to the configuration of this embodiment, when the rear end plate 3 is subjected to vibration during engine operation, the vibration of the portion of the rear end plate 3 that protrudes from the cylinder block 1 is transmitted to the vibration isolating weight 4. Therefore, it is suppressed.
Therefore, noise caused by vibrations in this part is reduced. Second embodiment Anti-vibration weight 1 shown in Fig. 5 A and B
4 is fixed to the rear end plate 3 by three legs 14d. Therefore, the portion 15 surrounded by the contact portion of each leg 14d with the rear end plate 3 has a triangular shape. Furthermore, weight 1
4 is a cylindrical portion 14a, a ring-shaped large diameter portion 14
b, a conical portion 14c, and each of the legs 14d. In this anti-vibration weight 14 as well, the area of the portion 15 surrounded by the contact portion of each leg 14d is the rear end plate 3 of the cylindrical weight having the same mass and height as shown by the imaginary line in FIG. 5A. The contact surface is sufficiently small compared to the contact surface, and the same function as in the first embodiment can be obtained. In FIG. 6, the horizontal axis shows the engine speed rpm, and the vertical axis shows the noise level dB of the rear end plate 3, and the curves a, b, c, and d are as shown in the table below.

[Table] As is clear from Figure 6, the masses of curves b and d are both 60 g, but the diameter of the contact surface of curve d is smaller than that of curve b, and as a result, the noise level is clearly lower for curve d. I understand that. [Effects of the Invention] As described above, in the present invention, the vibration of the rear end plate protruding from the cylinder block is suppressed by the anti-vibration weight during engine operation. Moreover, this anti-vibration weight is fixed to the rear end plate via multiple legs and has a cross-sectional area larger than the area surrounded by the contact parts of each leg, so it has the same mass and the same height. Compared to the case where the entire end face of the weight is in direct surface contact, fixing the weight has less effect on the rigidity of the rear end plate, and as a result, the natural frequency of the rear end plate can be kept low. Noise level is effectively reduced.

[Brief explanation of the drawing]

Figures 1 and 2 (a) and (b) show a first embodiment of the present invention. Figure 1 is a side view showing the arrangement of a vehicle engine, clutch housing, and rear end plate, and Figure 2 (a) is a rear end plate. FIG. 2B is a side view showing the state in which the anti-vibration weight is attached to the body, and FIG. 2B is a plan view of the anti-vibration weight. FIG. 3 is a side view illustrating the state in which a conventional anti-vibration weight is attached, in correspondence with FIG. 2A. FIG. 4 is an explanatory diagram showing the principle of an embodiment of the present invention. Fifth
Figures A and B show the second embodiment of the present invention, Figure 5 A is a side view showing how the anti-vibration weight is attached to the rear end plate in correspondence with Figure 2 A, and Figure 5 B is is a plan view of the anti-vibration weight. FIG. 6 is a characteristic diagram showing the results of experimental use of the anti-vibration weight. 3... Rear end plate, 4, 14... Anti-vibration weight, 4a, 14d... Leg, 12, 15...
The part enclosed by each leg.

Claims (1)

[Claims for Utility Model Registration] A configuration in which the lower part of the rear end plate assembled between the cylinder block and clutch housing of a vehicle engine protrudes from the cylinder block and closes the open lower part of the clutch housing. A substantially cylindrical anti-vibration weight is fixed to a portion of the rear end plate extending from the cylinder block via a plurality of legs formed integrally with the anti-vibration weight, and the anti-vibration weight is
A vibration isolation structure for a rear end plate in a vehicle engine, comprising a portion having a larger cross-sectional area than the area surrounded by the contact portion of each leg with respect to the rear end plate.