JPH0141657Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound insulation device for reducing noise leaking between horizontal joists at the bottom of a truck bed.

FIG. 1 shows a conventional cargo truck, in which a cargo platform 2 is provided behind a driver's seat 1. This carrier 2
is supported on the top of a pair of vertical joists 4 installed at the top of both sides of the frame 3 and a plurality of horizontal joists 5 installed at predetermined intervals so as to be perpendicular to the vertical joists 4. . In the figure, 6 is the wheel, E is the engine mounted in the engine room below the driver's seat 1, 7 is the transmission installed behind the engine E, and 13 is the transmission 7.
and a propeller shaft that connects a final reduction gear (not shown) that drives the rear wheels.

In recent years, in order to reduce vehicle noise in trucks and the like, the engine E, transmission 7, etc. have been covered with sound insulating covers, etc., but the noise generated from these sound sources leaks rearward, causing the loading platform 2 to be covered. There was a problem with leakage from below.

For this reason, a device has been proposed in which the space between the vertical joists 4 and the horizontal joists 5 is shielded with a sound insulating material to suppress the noise leaking to the outside from the rear (see Japanese Utility Model Application Publication No. 57-28073). However, the problem was that the shielding area was wide and the cost was high.

Also, for example, the Utility Model No. 54 proposed by the applicant
Japanese Patent No. 23413 proposes a system in which a sound absorbing member is provided so as to surround the frame and the lower part of the loading platform, but like the above-mentioned known example, the shielding portion is wide and the cost is high.

It is generally known that noise sources such as engines and transmissions are covered, but for cooling purposes, the direction in which the vehicle is traveling is left open to improve ventilation, which causes noise to be emitted to the rear.
The emitted noise was propagating from between the floor joists to the sides of the truck.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sound insulating device for a truck that can insulate noise emitted from between the floor joists using a minimum number of sound insulating members, and is easy to install and saves materials.

As a result of various studies, the inventor of the present invention found that in trucks where the transmission is installed near the front end of the truck bed, there is little point in extending the transmission to the rear of the bed as in the prior art, and it is therefore wasteful. I understood.

According to the invention, a vertical joist is provided on the frame of the truck, a horizontal joist is disposed substantially at right angles to the vertical joist, a loading platform is mounted on the horizontal joist, and the transmission is arranged on the loading platform. In the truck installed at the bottom of the loading platform near the front end of the truck, a sound insulating cover with an opening at the rear is provided around the engine, and a shielding member is installed to cover the gap between the horizontal joists installed at the bottom of the loading platform. , the front end of the shielding member is located at the front end of the loading platform and forward of the rear end of the transmission, and the rear end of the shielding member is located forward of the center of the loading platform and behind the rear end of the transmission. Located on the side.

As will be described later with reference to FIG. 7, it has been found that the noise from the transmission etc. can be sufficiently shielded by providing a shielding member of about 2 m. The reason for this is presumed to be that the noise is sufficiently attenuated by reflection etc. during this period.

Therefore, by defining the position of the rear end of the shielding member as described above, material costs and man-hours are saved;
Costs can be reduced, and noise emitted to the sides of the truck can be sufficiently reduced. Therefore, it can be said to be an energy-saving sound insulation device. In particular, if a sound insulating cover is installed to prevent noise from the engine and a cooling air passage is opened at the rear to cool the engine, the engine noise will be radiated rearward through the opening. According to the present invention, such noise, that is, muffled sound, can be effectively reduced by the shielding member, and the shielding member only needs to be placed on the front side of the loading platform, making it extremely suitable as a sound insulation device for engine and transmission noise. It is.

Although there is a space between the rear end of the driver's seat and the cargo bed, this space has little effect on muffled noise even if no shielding member is provided, and rather has a cooling effect on the transmission.

When implementing the present invention, the sound insulating cover provided around the engine and having an opening at the rear may be, for example, a cab-side side cover, a frame-side side cover,
It is preferable to use a front undercover, an undercover, a rear cover, a side rear cover, or a mission cover if necessary. These covers can be constructed separately or integrally, and in some cases, some of them can be omitted.

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

In this invention, as shown in Fig. 2, the horizontal joist 5 is
In the gap 8, a front portion A of the loading platform 2 is shielded by a sound insulating member. The appropriate length of this front portion A is about 2 m when the length of the loading platform 2 is 7 to 9 m. The reason why only the front part of the cargo bed 2 is shielded is that the engine E and transmission 7 are covered by the cab side cover 21, the frame side side cover 22, the front undercover 23, the undercover 24, the rear cover 25, and the side cover 21. When covered with rear cover 26, transmission cover 27, etc.
Noise leaks from the rear which is not covered by the cover, and leaks to the outside from the bottom of the loading platform, but from the tip of loading platform 2
At a distance of more than 2m, the leaked sound will be attenuated.
This is because we focused on the fact that even if only the front portion of the loading platform 2 is shielded, substantially the same sound insulation effect can be obtained.

According to the embodiment shown in FIG. 3, an elastic material 9 such as rubber is adhered to the gap 8 of the horizontal joist 5 with an adhesive. Therefore, the gap 8 between the horizontal joists 5 is shielded by the elastic material 9.

According to another embodiment shown in FIG.
The space 8 is shielded. And this cover member 1
Sound absorbing material 1 such as glass wool is placed inside 0 and 10.
1 is filled.

According to yet another embodiment shown in FIG.
The gap 8 between the horizontal joists 5 is substantially shielded by a and 12a. In this case, the cover plate 12 extends slightly forward to cover the upper part of the transmission 7, thereby further enhancing the sound insulation effect. In addition, 13 in the figure
is the propeller shaft.

According to yet another embodiment shown in FIG.
Both side edges 12a', 12a' of the cover plate 12' extend further downward and cover both sides of the transmission 7 and the propeller shaft 13, and the lower edge thereof is attached via the mounting fittings 14, 14. It is screwed to the frame 3. Therefore, the noise generated near the transmission 7 and the propeller shaft 13 can be prevented from leaking to the side, and the overall sound insulation effect can be further enhanced.

FIG. 7 shows that in the sound insulation device shown in FIG.
The sound insulation effect when the length of the shielding portion by the elastic material 9 is changed is shown. In the figure, the X axis is
Based on the engine position, the distance from there toward the front or rear is shown at 1m intervals, and the Y-axis shows the noise level (dbA) at each position. Noise measurements were performed at 4-speed acceleration (1650 rpm to 2500 rpm). Among the broken lines showing these results, line a is not shielded by the elastic material 9, and line b is from the side edge of the loading platform 2.
1m shielded, line c is 2m shielded from the tip of loading platform 2, line d is 3m shielded from the tip of loading platform 2, line e is 4m shielded from the tip of loading platform 2, line f is This figure shows a shield of 5 m from the tip of the loading platform 2. In this case, the length of the loading platform 2 is 9.2 m. As is clear from the figure, a shield c that covers a length of 2 m or more from the tip of the loading platform 2,
There is not much difference between d and e in terms of sound insulation effect,
Furthermore, a remarkable effect is observed when compared with the case a which is not shielded by the elastic material 9 and the case b where 1 m from the tip of the loading platform 2 is shielded. Therefore, in the case of this truck, by shielding 2 m from the tip of the loading platform 2, an excellent sound insulation effect can be obtained at low cost. In FIG. 7, the front end of the transmission is located 0.72 m behind the center of the engine, and the rear end is located 1.42 m behind the center of the engine. The front end of the cargo bed is located 1.09m from the center of the engine.

In addition, in the present invention, the front part of the loading platform 2 means
As mentioned above, it means a length that is not much different in terms of sound insulation effect than when shielding a longer length, and this length is, for example, when the length of the loading platform 2 is 9.2 m
It will be around 2m, but in reality this should be determined on a case-by-case basis.

As explained above, according to the present invention, the front part of the loading platform is substantially shielded by the sound insulating member in the space between the horizontal joists, so an excellent sound insulating effect can be obtained at low cost. be able to.

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a conventional truck, Fig. 2 is a schematic side view of a truck implementing the present invention, and Fig. 3 is a schematic side view of a conventional truck.
4 is a sectional view showing another embodiment, FIG. 5 is a sectional view showing still another embodiment, and FIG. 6 is a sectional view showing still another embodiment. A sectional view showing an example, and FIG. 7 are charts showing noise measurement results. 1... Driver's seat, 2... Loading platform, 3... Frame,
4...Vertical joist, 5...Horizontal joist, 6...Wheel, 7...
...Transmission, 8...Between, 9...Elastic material, 10...Cover member, 11...Sound absorbing material, 12
...Cover plate, 12a...Side edge, 13...Propeller shaft, 14...Mounting bracket, A...Front part.

Claims (1)

[Scope of claims for utility model registration] (1) Vertical joists are provided on the frame of the truck,
In a truck in which a horizontal joist is disposed substantially perpendicular to the vertical joist, a cargo bed is mounted on the horizontal joist, and a transmission is provided at the bottom of the bed near the front end of the bed, the engine A sound insulating cover that is open at the rear is provided around it, and a shielding member is provided to shield between the horizontal joists provided at the bottom of the loading platform, and the front end of the shielding member is the front end of the loading platform, and the transmission A sound insulation device for a truck, characterized in that the rear end of the shielding member is located in front of the rear end of the transmission, and the rear end of the shielding member is located in front of the center of the loading platform and behind the rear end of the transmission. (2) The sound insulating device for a truck according to claim 1, wherein the sound insulating member shields approximately 2 meters rearward from the front end of the loading platform.