JP7667220B2 - Grommet - Google Patents

Description

This invention relates to a grommet that protects a wire harness that passes through a panel.

Various vehicles, such as automobiles, ships, and aircraft, are divided into multiple spaces by panels made of steel or the like, and devices arranged in different spaces are connected by wire harnesses that pass through through holes formed in the panels. When wiring the wire harness through such through holes in the panel, grommets are provided in the through holes to prevent damage to the wire harness due to contact with the panel, and to prevent the intrusion of sound, water, dust, etc. through the through holes. For example, in a vehicle such as an automobile, the passenger compartment and the engine room are separated by a body panel such as a dash panel, and a wire harness is inserted through a cylindrical portion of a grommet attached to a through hole formed in the dash panel to connect a battery installed in the engine room as a power supply source to various electrical devices arranged in the passenger compartment to supply power (for example, Patent Document 1).

In addition to the main through-hole tubular portion (through-hole tubular portion) through which the aforementioned wire harness passes, some grommets are provided with an auxiliary tubular portion (one-side closed tubular portion) through which wire harnesses, piping, etc. can be inserted separately if necessary, such as when adding equipment to the vehicle interior, to enhance expandability. Such auxiliary tubular portions are formed with one end closed, and when the auxiliary tubular portion is not in use, they separate the inside and outside of the vehicle body panel to prevent sounds, etc. from the outside of the vehicle from entering the inside of the vehicle, and when necessary, such as when adding equipment, the closed end can be cut off and the necessary wire harnesses and piping can be inserted through the auxiliary tubular portion.

JP 2016-159890 A

However, although a grommet with an auxiliary tubular portion can increase the expandability of the grommet by the auxiliary tubular portion, when the auxiliary tubular portion is not in use, for example, the driving noise of the power source such as an engine or motor, or road noise during driving, enters the inside of the auxiliary tubular portion from the open end, and the sound generated by the resonance phenomenon in the auxiliary tubular portion is transmitted to the passenger compartment, causing discomfort to the occupants and impairing the quietness of the cabin. Although it is possible to prevent such a resonance phenomenon by attaching a silencer such as that disclosed in Patent Document 1 to the open end of the auxiliary tubular portion, the need to prepare and attach a separate silencer makes the work complicated, and there is also a concern that the silencer may fall off due to vibrations during driving.

In other words, the present invention aims to provide a grommet with a one-sided closed tube section that can suppress the discomfort caused by the resonance phenomenon.

In order to overcome the above problems and achieve the intended purpose, the first means comprises:
A grommet to be attached to a through hole formed in a panel,
A frustum-shaped portion having an inner diameter gradually decreasing;
a through-hole tube portion provided on the small diameter side of the frustum portion, having both ends open, through which a cord-like body can be inserted;
a panel engagement portion provided on a large diameter side of the frustum portion and engaging with an inner peripheral edge of the through hole;
A one-sided closed tube portion is provided on the frustum portion and one end of the one-sided closed tube portion is closed.
The gist of the invention is that the length of the one-side closed tube section from the closed portion to the open end is set to a length such that the resonance frequency of the one-side closed tube section is 2,000 Hz or less or 4,000 Hz or more.
In this way, by forming the pipe length from the closed portion to the open end of the one-sided closed pipe section to be 20 mm or less or 45 to 60 mm, the resonance frequency in the one-sided closed pipe section can be set to 2,000 Hz or less or 4,000 Hz or more. This makes it difficult to hear the sound generated by the resonance phenomenon in the one-sided closed pipe section, and reduces the discomfort felt by personnel without using a separate part such as a silencer. In addition, since there is no need to use a silencer, the work of attaching the grommet to the panel can be improved, and unnecessary materials generated when using the one-sided closed pipe section, such as when adding equipment, can be reduced.

The second means is
The one-side closed tube section is formed so that its length can be expanded or contracted, and the length of the tube in a contracted state is set so that the resonance frequency of the one-side closed tube section is 2,000 Hz or less or 4,000 Hz or more.
In this way, since the one-sided closed pipe section can be expanded and contracted, the sound generated by the resonance phenomenon can be made difficult to hear by shortening the one-sided closed pipe section when not in use, and the one-sided closed pipe section can be extended when in use to improve the retention of wire harnesses, piping, etc. that are inserted into the one-sided closed pipe section.

The third means is
The one-side closed pipe portion includes a base pipe portion connected to the frustum portion, a closed pipe portion whose protruding end side is closed by the closing portion, and a connecting pipe portion connecting the base pipe portion and the closed pipe portion,
The gist of the invention is that the length of the one-side occluded pipe section can be extended or contracted by transforming the connecting pipe section into a first state in which it is positioned so as to be connected to the outside of the base pipe section, and a second state in which it is positioned inside the base pipe section, inverted from the first state.
In this manner, the length of the one-side closed pipe section can be easily changed by pushing the closed pipe section into or pulling it out of the base pipe section.

The fourth means is
The one-side closed pipe section is formed so that the pipe length can be expanded or contracted on both ends of the closed end and the open end closed by the closing section.
In this way, by making it possible to expand and contract the pipe length at both ends, the closed end and the open end, the one-sided closed pipe section can be shortened when not in use to make it difficult to hear sounds generated by resonance, and the one-sided closed pipe section can be extended when in use to improve the retention of wire harnesses, piping, etc. that are inserted through the one-sided closed pipe section.

The present invention can reduce discomfort caused by resonance in the one-sided closed tube section when not in use.

1 is a schematic diagram of a vehicle equipped with a grommet according to the present invention; FIG. 1 is a schematic perspective view of a grommet according to a first embodiment. FIG. 2 is a vertical cross-sectional view of the grommet according to the first embodiment. FIG. 1 is a graph showing equal cloud curves. 13A is an enlarged longitudinal cross-sectional view of a main portion of a grommet according to a second embodiment, in which (a) shows a state in which a one-side closed pipe portion is in a standard state, and (b) shows a state in which a one-side closed pipe portion is in a shortened state. 13A is an enlarged longitudinal cross-sectional view of a key portion of a grommet according to a third embodiment, in which (a) shows a state in which a one-side closed pipe portion is in a standard state, and (b) shows a state in which both ends of the one-side closed pipe portion are in a shortened state.

Next, the grommet of the present invention will be described below with reference to the attached drawings. In this embodiment, a grommet that is attached to a through hole provided in the dash panel of a vehicle such as an automobile will be described as an example.

(First embodiment)
As shown in Fig. 1, the grommet 10 protects a wire harness WH that is routed through a through hole 50a provided in a dash panel 50 that separates an engine room ER provided in front of a passenger compartment HR of an automobile MT from the inside of the passenger compartment HR, and is made of an elastically deformable elastic material such as EPDM rubber. As shown in Fig. 2 or 3, the grommet 10 includes a frustum-shaped frustum portion 12 whose inner diameter gradually decreases, and a through-shaped tube portion 14 provided so as to protrude in the axial direction of the frustum portion 12 from the end of the small diameter side of the frustum portion 12. The through-shaped tube portion 14 is formed in a cylindrical shape with both ends open, with the protruding end being open and the base end side connected to the frustum portion 12 being open so as to connect to the inside of the frustum portion 12, and the frustum portion 12 and the through-shaped tube portion 14 form a funnel shape. This allows a wire harness WH that has been passed through the inside of the frustum portion 12 from the engine room ER side to be inserted into the through-hole pipe portion 14 and wired to the passenger compartment HR side.

In addition, the grommet 10 is provided with a circular large diameter portion 16 formed at the large diameter end of the frustum portion 12 with a diameter larger than the through hole 50a of the dash panel 50, and a groove-shaped panel engagement portion 18 with which the inner peripheral edge of the through hole 50a of the dash panel 50 can engage is provided between the large diameter end of the frustum portion 12 and the large diameter portion 16. Here, the outer peripheral edge of the large diameter end of the frustum portion 12 is formed to have a diameter larger than the through hole 50a of the dash panel 50, and the panel engagement portion 18 is formed with a diameter approximately the same as that of the through hole 50a. In other words, when the small diameter side (through-shaped tube portion 14) of the frustum portion 12 is inserted into the through hole 50a from one side of the dash panel 50 (for example, the engine room ER side), the frustum portion 12 elastically deforms, and the inner peripheral edge of the through hole 50a engages with the panel engagement portion 18, thereby attaching the grommet 10 to the dash panel 50. In this way, by inserting the wire harness WH through the grommet 10 attached to the through hole 50a of the dash panel 50, the wire harness WH is protected from the edge of the through hole 50a of the dash panel 50 and water, dust, etc. are prevented from entering the vehicle interior through the through hole 50a.

In addition, the frustum portion 12 of the grommet 10 is provided with a one-sided closed tube 20 with one end closed, extending in the axial direction of the frustum portion 12. The one-sided closed tube 20 includes a closed tube portion 24 that extends in the axial direction of the frustum portion 12 so as to connect to the outer surface side (small diameter side) of the frustum portion 12 and has a protruding end side blocked by a blocking portion 22, and an open tube portion 26 that extends in the axial direction of the frustum portion 12 so as to connect to the inner surface side of the frustum portion 12 and has both ends open. That is, the one-sided closed tube 20 is formed so that the closed tube portion 24 and the open tube portion 26 are connected to each other and form a closed tube with one end blocked by the blocking portion 22. In addition, the closed tube portion 24 has a flange portion 28 that protrudes radially outward in a circular ring shape, which is provided at the protruding end of the closed tube portion 24 and at a position spaced apart from the protruding end toward the base end. The blocking portion 22 of the blocking pipe portion 24 is positioned closer to the protruding end of the blocking pipe portion 24 than between the flange portions 28, and by cutting the one-side blocking pipe 20 at the gap 28a between the flange portions 28, the blocking portion 22 can be removed and the wire harness WH or other piping can be inserted into the one-side blocking pipe 20.

This one-sided closed tube 20 is a closed tube with one end blocked by a closed section 22, and a resonance phenomenon occurs when sound enters from the open end (the end of the open tube section 26). Here, sounds that humans can hear (audible range) are generally in the frequency range of 20 Hz to 20,000 Hz, and it is known that the sense of loudness (loudness) of a sound perceived by humans varies depending on the frequency even if the physical sound pressure is the same. Equal loudness curves, which represent the relationship between the frequency and sound pressure at which humans perceive a sound as being equal loudness, are standardized in the international standard ISO 226:2003 (see Figure 4). In other words, this equal loudness curve shows that sounds in the audible range, especially those with frequencies in the range of 2,000 Hz to 4,000 Hz, are particularly easy for the human ear to hear. In other words, it can be seen that sounds in the frequency range of 2,000 Hz to 4,000 Hz are easily perceived by humans even if they have a slight sound pressure, which impairs quietness and causes discomfort to people.

The pipe length L (length from the pipe inner surface side of the closed section 22 to the open end of the open pipe section 26) of the one-side closed pipe 20 in the grommet 10 according to the present invention is set so that the resonance frequency f (Hz) of the sound incident on the one-side closed pipe 20 is F<2,000 Hz or F>4,000 Hz. Here, the resonance frequency f (Hz) of a closed pipe with one end closed can be calculated by the formula (1): f = (2n-1)V/4L, where V (m/s) is the sound speed, L (m) is the pipe length, and n is the order of resonance. Here, the relationship between the pipe length L and the resonance frequency in the standard environment (standard atmosphere (1 atmospheric pressure, 15°C), sound speed V = 340 m/s) in which a vehicle using the grommet 10 of the present invention is used is shown in Table 1.

That is, the one-side closed pipe 20 of the grommet 10 is formed so that the pipe length L is in the range of L≦20 mm, 45 mm≦L≦60 mm, so that the resonance frequency of the one-side closed pipe 20 in standard atmosphere when the one-side closed pipe 20 is not used can be 2,000 Hz or less or 4,000 Hz or more. Specifically, in this embodiment, the pipe length L is set to 60 mm. This makes it difficult to hear the sound generated by the resonance phenomenon in the one-side closed pipe 20, thereby suppressing the discomfort of the occupants and improving the quietness in the vehicle interior HR. That is, the discomfort of the occupants can be suppressed without attaching a separate part such as a silencer to the grommet 10. In addition, since there is no need to use a silencer, the installation work of the grommet 10 on the panel can be improved and unnecessary materials generated when using the one-side closed pipe 20 when adding equipment, etc. can be reduced. Furthermore, since there is no need to attach a silencer to the one-side closed pipe 20, there is no risk of the silencer falling off due to external factors such as vibrations while driving, and good quietness can be maintained.

(Second Example)
Next, a grommet according to a second embodiment will be described. The basic configuration of the grommet according to the second embodiment is basically the same as the configuration of the grommet 10 according to the first embodiment described above, but differs in the configuration of the one-side occlusion tube 20. Therefore, in the following description, the configuration that differs from the grommet 10 according to the first embodiment will be described, and the common configuration will be denoted by the same reference numerals and will not be described.

The one-side closed pipe section 30 of the grommet 10 according to the second embodiment includes a base pipe section 32 that is open at both ends extending in the axial direction of the frustum section 12 so as to connect to the outer surface side (small diameter side) of the frustum section 12, a closed pipe section 34 whose protruding end side is closed by a closing section 22, and a connecting pipe section 36 that connects the base pipe section 32 and the closed pipe section 34. The base pipe section 32, the closed pipe section 34, and the connecting pipe section 36 are formed to form a series of tubes that are mutually connected on the outer surface side of the frustum section 12. In other words, the connecting pipe section 36 is provided to connect the open end (protruding end) of the base pipe section 32 and the open end of the closed pipe section 34. The base pipe section 32, the closed pipe section 34, and the connecting pipe section 36 are formed so that their axes coincide with each other. Also, like the first embodiment, an open tube section 26 with open ends is provided on the inner surface of the frustum section 12, and the open tube section 26 is connected to the base tube section 32 and is formed to form a closed tube with one end closed by the closing section 22.

Here, the connecting pipe section 36 is formed so that its outer diameter is smaller than the inner diameter of the base pipe section 32, and the blocking pipe section 34 is formed so that its outer diameter is smaller than the inner diameter of the connecting pipe section 36. That is, in a standard state (first state, see FIG. 5(a)) in which the connecting pipe section 36 is positioned so as to be connected to the outside of the base pipe section 32, by pushing the blocking pipe section 34 from its protruding end side (blocked end side) toward the base end side, the connecting pipe section 36 is inverted and positioned inside the base pipe section 32, and can be deformed to a shortened state (second state, see FIG. 5(b)) in which the blocking pipe section 34 is positioned inside the inverted connecting pipe section 36, and by pulling the blocking pipe section 34 from its base end side toward the protruding end side (blocked end side) in this second state, the connecting pipe section 36 can be deformed to the standard state in which it is connected to the outside of the base pipe section 32. In this way, the one-side occluding pipe 20 of the grommet 10 according to the second embodiment can expand or contract its pipe length L. In addition, the flange portion 28 provided on the protruding end side of the occluding pipe portion 34 is located outside the base pipe portion 32 and the connecting pipe portion 36 in a contracted state, so that the occluding pipe portion 34 can be easily pulled out by pinching the flange portion 28.

The one-side closed tube 20 of the grommet 10 according to the second embodiment is formed so that its tube length L in the shortened state is in the range of L≦20 mm, 45 mm≦L≦60 mm, and specifically, in this embodiment, the tube length L in the shortened state is formed to be 50 mm. By setting the tube length L of the one-side closed tube 20 in this manner, the resonance frequency of the one-side closed tube 20 in standard atmosphere when the one-side closed tube 20 is not in use can be set to 2,000 Hz or less or 4,000 Hz or more. As a result, by shortening the one-side closed tube 20 when not in use, it is possible to make it difficult to hear the sound generated by the resonance phenomenon in the one-side closed tube 20, which can suppress the discomfort given to the occupants and increase the quietness in the cabin, and other effects similar to those of the grommet 10 according to the first embodiment can be expected. When adding equipment, etc., the one-side occluded pipe 20 can be placed in a standard state (extended state) to insert a wire harness WH, piping, etc. through it, thereby ensuring a sufficient pipe length for the one-side occluded pipe 20 and improving the retention of the wire harness WH, piping, etc. that are inserted through the one-side occluded pipe 20. In addition, the pipe length of the one-side occluded pipe 20 can be easily changed by pushing the occluded pipe portion 34 into or pulling it out of the base pipe portion 32, improving workability.

(Third Example)
Next, a grommet 10 according to a third embodiment will be described. The basic configuration of the grommet 10 according to the third embodiment is basically the same as that of the grommet according to the second embodiment described above, but differs in the configuration of the one-side closed tube. Therefore, in the following description, the configuration that differs from that of the grommet 10 according to the second embodiment will be described, and the common configuration will be denoted by the same reference numerals and will not be described.

The one-side occluded pipe 40 of the grommet 10 according to the third embodiment is configured so that the pipe length L can be changed on both the closed end side closed by the occluding portion 22 and the open end side. Specifically, the one-side occluded pipe 40 of the grommet 10 has a base pipe section 32, a occluded pipe section 34, and a connecting pipe section 36 (hereinafter, referred to as the first connecting pipe section in the third embodiment) on the outer surface side of the frustum section 12, as in the second embodiment described above. In addition, in the following description, the reference state in which the first connecting pipe section 36 is positioned so as to be connected to the outside of the base pipe section 32 is referred to as the first reference state, and the shortened state in which the first connecting pipe section 36 is inverted and positioned inside the base pipe section 32 and the occluded pipe section 34 is positioned inside the inverted first connecting pipe section 36 is referred to as the first shortened state.

The inner surface of the frustum portion 12 is provided with a first open tube portion 42 connected to the frustum portion 12, a second connecting tube portion 44 provided at the protruding end of the first open tube portion 42 and extending in the axial direction of the frustum portion 12, and a second open tube portion 46 provided at the protruding end of the second connecting tube portion 44 and extending in the axial direction of the frustum portion 12. The first open tube portion 42, the second connecting tube portion 44, and the second open tube portion 46 are formed so that their axes coincide with each other and both ends are open to form a series of tubes that communicate with each other, and the first open tube portion 42 is formed so that it communicates with the base tube portion 32 and one end of the one-side closed tube 40 is closed by the closing portion 22 to form a closed tube.

Here, the second connecting pipe portion 44 is formed so that its outer diameter is smaller than the inner diameter of the first open pipe portion 42, and the second open pipe portion 46 is formed so that its outer diameter is smaller than the inner diameter of the second connecting pipe portion 44. That is, in a second reference state (third state, see FIG. 6(a)) in which the second connecting pipe portion 44 is positioned so as to be connected to the outside of the first open pipe portion 42, by pushing the second open pipe portion 46 from its protruding end side (open end side) toward the base end side, the second connecting pipe portion 44 is inverted and positioned inside the first open pipe portion 42 and can be deformed to a second shortened state (fourth state, see FIG. 6(b)) in which the second open pipe portion 46 is positioned inside the inverted second connecting pipe portion 44, and by pulling the second open pipe portion 46 from its base end side toward the protruding end side in this second state, the second connecting pipe portion 44 can be deformed to the second reference state in which the second connecting pipe portion 44 is connected to the outside of the first open pipe portion 42. In this way, the one-side closed pipe 40 of the grommet 10 according to the third embodiment is capable of expanding and contracting the pipe length L at both ends (closed end and open end). In addition, a flange portion 48 that protrudes radially outward in an annular shape is provided on the protruding end side of the second open tube portion 46, and this flange portion 48 is located outside the first open tube portion 42 and the second connecting tube portion 44 in the second contracted state, so that the second open tube portion 46 can be easily pulled out by pinching the flange portion 48.

The one-side closed tube 40 of the grommet 10 according to the third embodiment is formed so that its tube length L is in the range of L≦20 mm, 45 mm≦L≦60 mm in at least one of the first and second shortened states. Specifically, in this embodiment, the tube length L in the first and second shortened states is formed to be 50 mm. By setting the tube length L of the one-side closed tube 40 in this manner, the resonance frequency of the one-side closed tube 40 in standard atmosphere when not in use can be set to 2,000 Hz or less or 4,000 Hz or more. As a result, by shortening the one-side closed tube 40 when not in use, it is possible to make it difficult to hear the sound generated by the resonance phenomenon in the one-side closed tube 40, which can suppress the discomfort given to the occupants and increase the quietness in the cabin, and other effects similar to those of the grommet 10 according to the first embodiment can be expected. When inserting a wire harness WH, piping, etc., into the one-side closed pipe 40, such as when adding equipment, the one-side closed pipe 40 can be set to the first reference state and the second reference state (extended state) to ensure a sufficient pipe length for the one-side closed pipe 40, thereby improving the retention of the wire harness WH, piping, etc., inserted into the one-side closed pipe 40. In addition, the length of the one-side closed pipe 40 can be easily changed by pushing or pulling the closed pipe portion 34 into or out of the base pipe portion 32, or the second open pipe portion 46 into or out of the first open pipe portion 42, improving workability.

In addition, if the tube length can be changed at both the closed end and the open end of the one-side closed tube 40, and the resonant frequency of the one-side closed tube 40 is set to 2,000 Hz or less or 4,000 Hz or more by manipulating one end side to shorten it (first shortened state or second shortened state), the installation workability of the grommet 10 can be further improved compared to when both ends are manipulated to shorten it (first shortened state and second shortened state). In addition, with a configuration in which both ends of the one-side closed tube 40 are manipulated to shorten it (first shortened state and second shortened state), the one-side closed tube 40 can be made more compact when not in use, and interference between the one-side closed tube 40 and other components can be prevented.

(Example of change)
The configuration of the embodiment is not limited to the above, and can be modified as follows, for example.
(1) Although the grommet has one one-side closed tube, the present invention is not limited to this, and the grommet may have a plurality of one-side closed tubes. Furthermore, the plurality of one-side closed tubes provided in the grommet do not need to have the same configuration, and one-side closed tubes of different configurations, such as the one-side closed tube 20 in the first embodiment and the one-side closed tube 30 in the second embodiment, may be provided.
(2) The configuration for enabling the length of the one-side closed tube to be extended or contracted is not limited to the configurations shown in the second and third embodiments, but the one-side closed tube may be formed into a bellows shape, and various conventionally known configurations for adjusting the length of the tubular body can be adopted.
(3) In the second embodiment, the tube length is configured to be extendable at the closed end of the one-side closed tube 30, and in the third embodiment, the tube length is configured to be extendable at both the closed end and the open end of the one-side closed tube 40, but the tube length may be configured to be extendable only at the open end of the one-side closed tube.

10 Grommet, 12 Frustrum portion, 14 Penetrating pipe portion, 18 Panel engagement portion 20, 30, 40 One-side closed pipe portion, 22 Closed portion, 32 Base pipe portion, 34 Closed pipe portion,
36 Connection pipe section

Claims (2)

A grommet to be attached to a through hole formed in a panel,
One end of the tube is closed, and the tube length is extendable and retractable.
The one-side closed pipe portion includes a base pipe portion, a closed pipe portion whose protruding end side is closed by a closing portion, and a connecting pipe portion connecting the base pipe portion and the closed pipe portion,
A grommet characterized in that the pipe length of the one-side closed pipe section can be expanded or contracted by deforming between a first state in which the connecting pipe section is positioned so as to be connected to the outside of the base pipe section, and a second state in which the connecting pipe section is inverted from the first state and positioned inside the base pipe section. A grommet to be attached to a through hole formed in a panel,
One end of the tube is closed, and the tube length is extendable and retractable.
The grommet is characterized in that the one-side closed pipe portion is formed so that the pipe length can be expanded or contracted on both ends of the closed end and the open end closed by the closing portion.

Images