JP7471645B2 - Automobile door structure - Google Patents

Description

This invention relates to an automobile door having a drain hole for draining water that has entered the interior, and to a door structure for reducing noise that enters through the drain hole and a decrease in insulation performance due to convection of the entered air.

In automobile doors, rainwater and other water cannot be avoided from entering through the gap between the window sash and the door panel, and to prevent accumulated water from corroding the bottom of the door, a drain hole is usually provided at the bottom of the door. Since this drain hole is usually provided in a part that leads to the outside of the vehicle, it is inevitable that noise such as road noise will enter through this drain hole. In addition, air currents that enter through this drain hole generate convection currents in the space inside the door, which is a factor that reduces the insulating performance of the door.

To prevent this noise from entering, for example, in JP 2008-265655, a part of the bent piece of the door panel where the drainage hole is formed is left at the top of the opening, and the bent piece blocks the entering noise. However, with this method, the width of the bent piece that acts as a soundproofing plate is limited to the width of the drainage hole, and the material and plate thickness are also limited, so there is a possibility that a sufficient soundproofing effect cannot be obtained.

In addition, JP 11-91633 A proposes an invention in which a grommet incorporating a flap that allows only water accumulated inside the door to be drained is attached to the door panel in order to achieve sufficient sound insulation. While this invention may be able to achieve sufficient sound insulation, it has the problem of increasing costs due to the cost of the grommet parts and the labor required to install the parts.

Patent Publication 2008-265655 JP 11-91633 A

In light of this background, the present invention aims to provide a means for reducing noise that enters through a drain hole in an automobile door that has a drain hole for discharging water that has entered the interior, with sufficient sound insulation effect, and for suppressing airflow that has entered through the drain hole from generating convection in the space inside the door, while achieving these objectives at the lowest possible cost.

The invention of claim 1 is a vehicle door structure that is composed of a door inner panel and a door outer panel, and has a drainage hole for water that has entered the interior provided at the bottom of the door inner panel, and is characterized in that a shielding portion is formed by applying an adhesive made of synthetic rubber or a hardening resin above the drainage hole of the door inner panel, and that when the door inner panel and the door outer panel are joined together by processing, the shielding portion is configured to be in close contact with the door outer panel.

With this configuration, the space above the drain hole at the bottom of the door is blocked by a shielding section that is tightly attached between the inner door panel and the outer door panel, effectively preventing noise that enters through the drain hole from being blocked by this shielding section and propagating into the space inside the door.
Similarly, airflow entering through the drainage hole is blocked by the shielding portion, thereby suppressing the occurrence of convection within the door space and improving the insulating effect.

The invention of claim 2 has the same features as claim 1, but is characterized in that the coating shape of the shielding portion is a shape that covers the top of the drainage hole, for example, an arc shape or an umbrella shape.

With this configuration, the shielding portion is shaped to cover the drainage hole, for example in an arc or umbrella shape, providing more effective sound insulation and heat insulation by suppressing the generation of convection.

The door structure of the present invention uses the adhesive originally used in the door assembly to construct the shielding portion, minimizing increases in cost and labor while providing effective sound insulation from the shielding portion and heat insulation by suppressing convection within the door space.

1 is a diagram showing a door panel in which an inner door panel and an outer door panel to which the present invention is applied are joined, viewed from the inner panel side. An enlarged drawing of the drain hole (part H) in the center of the bottom of the door. Cross section I-I at the center of the drain hole in section H. A drawing showing the pattern of the shielding part shape. A graph comparing transmission loss in an anechoic chamber with and without shielding.

1 Door panel 2 Door outer panel 3 Door inner panel 5 Water drain hole 6 Shielding part

The following describes an embodiment of the present invention with reference to the drawings. Note that the following description of the embodiment is merely an example and is not intended to limit the present invention, its applications, or its uses.

(Configuration of this embodiment)
Fig. 1 is a diagram of a door panel according to an embodiment to which the present invention is applied. The diagram is a diagram of the door panel in a state in which the door inner panel and the door outer panel are joined by hemming, as viewed from the inner panel side. In this embodiment, the door inner panel and the door outer panel are joined by hemming, but various other joining methods such as adhesives, welding, mechanical fastening, welding, and fitting can also be used.

It is inevitable that rain and other water will get into the door through the gap between the outer door panel and the window glass. If water accumulates inside, it can cause corrosion inside the door. To prevent this, a drain hole is provided at the bottom of the door. In this embodiment, to join the two panels, an adhesive is applied and the periphery of the outer door panel is hemmed to the inner door panel. This drain hole is provided in the area just above the hemmed area, on the inner door panel side. As shown in Figure 3, when the door is closed, the bottom of the door where the drain hole is located faces the body side sill (not shown).

As shown in FIG. 1, in this embodiment, drainage holes 5 are provided in three places on the left and right ends and in the center of the lower part of the door. As mentioned above, these drainage holes are provided for the purpose of draining water, but because they open to the inside of the door, they are a factor in allowing outside noise, including road noise, to enter the vehicle through the gap between the lower part of the door and the body side sill. Noise that enters the inside of the door enters the vehicle from the interior space of the door through the door inner panel and door lining, causing the noise inside the vehicle to worsen.

Another problem is that airflow entering through the drain holes creates convection in the interior space of the door, which reduces the door's insulation performance. In recent years, there has been a demand for improved fuel efficiency, and the deterioration of the insulation performance of the body, including the doors, which have a major impact on heating and cooling efficiency, is a major problem.

As shown in FIG. 2, in this embodiment, the drainage hole 5 is a rectangle with a side of about 10 mm. This drainage hole 5 is usually formed by punching with a press. In the door assembly process, several types of adhesives made of synthetic rubber or hardening resin are used, such as a hemming adhesive used for the hemming part of the outer periphery, and a mastic sealer used between the door and the reinforcement to increase the rigidity of the door surface. The most suitable of these several types of adhesives used in the door assembly process is reused in the process and applied to the top of the drainage hole 5 to form a shielding part. This makes it possible to minimize the increase in labor and costs. In this embodiment, the mastic sealer is reused and applied to the top of the drainage hole 5. The mastic sealer is applied to a predetermined shape by an application gun (not shown) attached to the tip of the sealing robot.

The coating shape of the shielding portion can be as shown in Figure 4, but the optimum shape is selected and used after comparing the effects on sound insulation and heat insulation performance through simulations and actual equipment verification. In this embodiment, the arc-shaped coating shape shown in Figure 4(b) was used.

The bottom of the door, where the drain hole is located, is near the joint between the inner door panel and the outer door panel, and in normal designs, the two panels are close to each other. In this embodiment, the distance between the two panels is about 1.5 mm. Because the diameter of the mastic sealer coming out of the nozzle of the application gun is about 3 mm, the mastic sealer adheres to both panels when the inner door panel and the outer door panel are joined. This means that the shielding part completely covers the space above the drain hole. Even if the distance between the inner door panel and the outer door panel exceeds the diameter of the sealer, the sealer can be applied in multiple stages to adhere to both the inner door panel and the outer door panel.

In addition, in order to ensure the rigidity of the door, a separate reinforcement from the inner door panel may be placed at the bottom of the door. In such cases, a mastic sealer is placed between the reinforcement and the outer door panel, adhering to both components and sealing off the upper space.

(Effects of this embodiment)
An experiment was carried out to verify the effect on sound insulation and heat insulation performance when a shielding portion of the shape shown in Fig. 4(b) is formed above the drainage hole 5. An arc-shaped shielding portion is formed with mastic sealer so as to cover the upper part of the drainage hole 5, and the mastic sealer is adhered to the door inner panel and the door outer panel as shown in Fig. 3. Shielding portions were also formed at all three drainage holes shown in Fig. 1.

First, Figure 5 shows a comparison of sound insulation performance in an experiment with and without a shielding section. The sound intensity method was used to measure the transmission loss of a door with a shielding section and a door without a shielding section. The experimental equipment consisted of an experimental door embedded in the wall separating the reverberation chamber and the semi-anechoic chamber. The experimental method involved playing a certain volume with a speaker in the reverberation chamber and measuring the sound (acoustic power) that transmitted through the door on the semi-anechoic chamber side to evaluate the transmission loss.

The door transmission loss shown in Figure 5 is a characteristic that corresponds to the sound insulation performance of the door, with a higher loss value indicating a higher sound insulation performance. Measurements were performed at different frequencies, measuring loss values at nine frequencies from 500 Hz to 3150 Hz. As a result, doors with shielding sections around 800 Hz and 1600 to 2500 Hz showed superior loss values, with an overall superior value of 0.3 dB obtained from 500 to 3150 Hz.

Next, the thermal insulation performance was compared by measuring the thermal conductivity W/(m・K) of the body part for doors with and without a shielding part. The measurement method used was a steady-state method using a thermostatic chamber to measure and evaluate the thermal conductivity (thermal insulation performance) (details are described in "Development of a method to measure and evaluate the thermal insulation performance of automotive door structures, and an investigation into the structural effects" by Matsumura Tadanori et al., Proceedings of the General Meeting and Lecture of the Chugoku-Shikoku Branch of the Japan Society of Mechanical Engineers, Vol. 57, 2019). As a result, the thermal conductivity of the door with the shielding part was 5.31 W/(m・K), while the door without the shielding part was 6.03 W/(m・K), resulting in a 12% improvement in the thermal conductivity of the door with the shielding part.

These results confirmed that doors with shielding sections have superior sound insulation and heat insulation performance to doors without shielding sections.

Claims (2)

A vehicle door structure including a door inner panel and a door outer panel, the door inner panel having a drain hole at a lower portion thereof for draining water that has entered the vehicle door structure,
Applying an adhesive made of synthetic rubber or hardening resin to an upper portion of the drainage hole of the door inner panel;
When the door inner panel and the door outer panel are joined together by processing, the adhesive also adheres to the door outer panel to form a shielding portion ,
The adhesive of the shielding portion is applied in a shape that covers only the upper part of the area adjacent to the drainage hole;
A vehicle door structure comprising: The adhesive of the shielding portion is applied in a shape that is linear, arcuate , U -shaped or umbrella-shaped so as to cover the upper portion of the drainage hole.
The vehicle door structure according to claim 1 .

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