Internal-combustion engines – Vibration compensating device
Reexamination Certificate
1998-11-13
2004-07-20
Pezzlo, Benjamin A. (Department: 3683)
Internal-combustion engines
Vibration compensating device
Reexamination Certificate
active
06763794
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration sound reducing device including a vibration absorbing means which is mounted to a passage defining structure for defining a liquid passage faced by at least a portion of a vibration generating section, and which is adapted to absorb a vibration transmitted from the vibration generating section through a liquid in the liquid passage. Particularly, the present invention relates to a vibration sound reducing device appropriately applied to a water-cooled internal combustion engine in which a cooling water passage including a water passage portion surrounding a cylinder portion as the vibration generating section is provided in an engine body.
2. Description of the Related Art
To reduce a piston slap sound caused by collision of a piston against an inner surface of the cylinder portion in a water-cooled internal combustion engine, the following techniques have been conventionally used: (1) a technique to suppress the amplitude of vibration to a small level by increasing the thickness of the cylinder portion; and (2) a technique to suppress the amplitude of vibration to a small level by increasing the thickness of an outer wall of a cylinder block.
Known structures for suppressing the vibration of non-compressable cooling water existing in a cooling water passage, include, for example, (3) a structure in which a sound shielding layer is provided outside the cooling water passage in the cylinder block with a partition wall interposed therebetween, as disclosed in Japanese Utility Model Application Laid-open No. 53-68814.
In the techniques (1) and (2), however, the weight of the engine body is increased due to the increase in thickness of the cylinder portion and the cylinder block. The structure (3) is a double, structure in which the cooling water passage and the sound layer are disposed through the partition wall interposed therebetween. Therefore, the structure (3) is complicated and is difficult to manufacture, resulting in an increased manufacture cost, and bringing about an increase in weight of the engine body.
Therefore, the present assignee has already proposed a vibration sound reducing device for a water-cooled internal combustion engine in Japanese Patent Application No. 8-351288, comprising a vibration absorbing means which is mounted to an outer wall of an engine body so as to occlude a through-bore that is provided in the outer wall of the engine body while facing a cooling water passage, the vibration absorbing means including an elastic membrane with one surface thereof facing the cooling water passage and with the other surface thereof facing a space.
With this proposed technique, a variation in pressure of the cooling water is absorbed by flexing of the elastic membrane with one surface thereof facing the cooling water passage. Thus, an exciting force applied from the cooling water to the outer wall of the engine body can be effectively reduced, and the piston slap sound radiated from the engine body can be reduced without an increase in weight of the engine body.
In the above proposed technique, however, a peripheral edge of the elastic membrane is secured by baking or the like to a member that is mounted to the engine body so as to occlude the through-bore. In such a structure in which the elastic membrane is fixed, it is difficult to ensure the satisfactory sealing between the cooling water passage and the space due to the water pressure in the cooling water passage or due to the deterioration of the elastic membrane. It is also considered that the peripheral edge of the elastic membrane is adhered to the member mounted to the engine body, but even in this case, it is difficult to ensure the satisfactory sealing property.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vibration sound reducing device, wherein the vibration sound such as the piston slap sound can be effectively reduced in a simple structure which brings about no increase in weight of the passage defining structure and moreover, the satisfactory sealing can be ensured.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a vibration sound reducing device comprising a vibration absorbing means which is mounted to a passage defining structure defining a liquid passage faced by at least a portion of a vibration generating section, the vibration absorbing means absorbing the vibration transmitted from the vibration generating section through a liquid in the liquid passage, wherein the vibration absorbing means comprises an occluding member mounted to an outer wall of the passage defining structure so as to occlude a through-bore which is provided in the outer wall of the passage defining structure and opens at an inner end thereof into the liquid passage, an elastic membrane with one of opposite surfaces thereof facing the liquid passage and with the other surface thereof facing a space defined between the elastic membrane and the occluding member, and a retaining member mounted to the occluding member for retaining the elastic membrane between the retaining member and the occluding member.
With such arrangement of the first feature, the vibration generated in the vibration generating section induces the vibration of the liquid in the liquid passage, but a variation in pressure of the liquid is absorbed by flexing of the elastic membrane with its one surface facing the liquid passage. Thus, the exciting force applied from the liquid to the passage defining structure is effectively reduced, and the vibration sound radiated from the passage defining structure is reduced. Moreover, the vibration absorbing means is mounted to a portion of the outer wall of the passage defining structure and hence, the increase in weight of the passage defining structure due to the mounting of the vibration absorbing means can be suppressed to a small level to the utmost. In addition, the elastic membrane is retained between the occluding member and the retaining member. Therefore, it is possible to avoid that the sealability is reduced due to the liquid pressure in the liquid passage or due to the deterioration of the elastic membrane, whereby the elastic membrane can be reliably retained between the occluding member and the retaining member. As compared with a vibration absorbing means including an elastic membrane secured directly to an occluding member by baking or adhesion, the sufficient sealability can be ensured.
According to a second aspect and feature of the present invention, in addition to the arrangement of the first feature, the occluding member has a cylindrical mounting portion projectingly provided at an inner end thereof; the elastic membrane includes an endless sealing portion which is in contact with a tip end face of the mounting portion, and a membrane portion formed at a thickness smaller than that of the sealing portion and integrally connected to an inner periphery of the sealing portion with a step formed therebetween; and the retaining member mounted to the occluding member with the sealing portion sandwiched between the retaining member and the tip end of the mounting portion is provided with a positioning portion which is engaged with the inner periphery of the sealing portion to position the elastic membrane in a plane perpendicular to an axis of the mounting portion. With such arrangement of the second feature, the sealing portion of the elastic membrane is accurately positioned and sandwiched between the mounting portion and the retaining member, whereby the sealability can be more sufficiently ensured to enhance the vibration absorbing characteristic.
According to a third aspect and feature of the present invention, in addition to the arrangement of the first feature, the occluding member has a cylindrical mounting portion projectingly provided at an inner end thereof; the elastic membrane includes an endless sealing portion which is in contact with a tip end face of the mounting portion,
Kamata Kojiro
Kawai Noriaki
Sakashita Masao
Sunaoka Motoyuki
Torikai Terukazu
Arent & Fox PLLC
Honda Giken Kogyo Kabushiki Kaisha
Pezzlo Benjamin A.
LandOfFree
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