JPH0553588A - Confined sound decreasing device for automobile - Google Patents

Abstract

PURPOSE:To provide the device which can effectively decrease confined sounds with constituting parts fewer than heretofore. CONSTITUTION:This confined sound decreasing device for automobiles is constituted by forming a trunk room 1 of an automobile of plural sheets of panels 2 to 5, etc., providing a vibration sensor 6 for measuring the vibration state of a spare tire pan 3 in one (spare tire pan 3) of the approximate opposite panels of the panels 2 to 5, providing an actuator 7 for controlling the vibration state of a trunk lid 2 in the other panel (trunk lid 2), and further providing a controller 8 for controlling an actuator 7 in such a manner that the trunk lid 2 vibrates at the same phase as the phase of the spare tire pan 3 when the signal measured by the vibration sensor 6 is inputted thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reducing muffled noise generated in a vehicle interior space.

[0002]

2. Description of the Related Art Generally, when a vehicle is traveling, a muffled sound is generated due to vibration of a panel forming a vehicle interior space.

In order to suppress this muffled sound, there is a method in which a vibration damping member is arranged on those panels or a vibration sensor and an actuator are set for each panel.

In the latter, the vibration sensor detects the vibration state of the panel, and the actuator suppresses the vibration of the panel based on this signal.

[0005]

However, in the case where the vibration damping member is provided on each panel, it is not possible to suppress the variation in the panel vibration due to the variation of each vehicle, and the countermeasure against the sound vibration phenomenon is taken. It cannot be fully implemented.

Further, in the latter method of damping each panel, the control device must be provided on all of the panels, resulting in high cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an apparatus which has fewer components than the conventional one and which can effectively reduce muffled noise.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and a vehicle compartment space of an automobile is formed by a plurality of panels, and one of the panels which substantially opposes each other. A vibration sensor for measuring the vibration state of the one panel, an actuator for controlling the vibration state of the other panel is provided on the other panel, and a signal measured by the vibration sensor is input. It is characterized in that the other panel is a muffled noise reducing apparatus for an automobile provided with a control device for controlling the actuator so as to vibrate in phase with the one panel.

[0009]

[Operation] According to such means, when the panel surrounding the vehicle compartment vibrates due to traveling of the automobile or the like, the vibration sensor detects one of the vibration states of the panels which substantially oppose each other.
Then, a signal from this vibration sensor is input to the control device, the actuator is controlled based on this value, and the other panel is vibrated in phase with respect to the one panel. If the panels facing each other like this vibrate in phase,
The pressure fluctuations of the air in the vehicle interior space are always in the opposite phase on both sides of the panel, and they cancel each other out to suppress the sound pressure level in the vehicle interior space to a low level.

Accordingly, by appropriately controlling the vibration of each panel, the level of the muffled sound can be ensured without being affected by the frequency band of the muffled sound in question and the variation among the vehicles. Can be reduced. Moreover, since the other panel is vibrated to reduce the muffled noise in response to the vibration of the one panel that is substantially opposite to the other panel, a pair of vibration sensor, actuator, and Since it suffices to prepare a control device, it is possible to reduce the number of parts as compared with the conventional device in which an actuator or the like is provided for each panel.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

1 to 5 are views showing an embodiment of the present invention.

First, the structure will be described. Reference numeral 1 in FIG.
A trunk room, which is a passenger compartment of an automobile, is defined by a trunk lid 2, a spare tire pan 3, a rear panel 4, a rear seat back panel 5, and the like.

The trunk lid 2 and the spare tire pan 3 are substantially opposed to each other, and the spare tire pan 3 is provided with a vibration sensor 6 for detecting the vibration of the spare tire pan 3, while the trunk lid 2 is provided. Is an actuator 7 for controlling the vibration state of the trunk lid 2.
Are arranged.

Further, a control device 8 for driving and controlling the actuator 7 by a signal from the vibration sensor 6 is provided.

More specifically, this actuator 7 is shown in FIG.
As shown in FIG. 3, when the control energy (current) from the control device 8 is input to the coil 9, a magnetic field is generated, the movable mass 10 of the magnet moves up and down, and the inertial force of the movable mass 10 causes the trunk lid 2 to move. When the reaction force is input to the side, the side of the trunk lid 2 is vibrated, and the vibration is fed back by the actuator sensor 11 to control the vibration to a predetermined vibration state.

As shown in FIG. 3, the spare tire pan 3 side has a sensor side panel mass M ₁ , rigidity K ₁ and damping characteristic C ₁ , and the trunk lid 2 side has an actuator side panel mass M ₂ and rigidity. It has K ₂ and damping characteristic C ₂ . Then, in the vibration sensor 6, the sensor side displacement x ₁₁ , velocity x
₁₂ (dx / dt) and acceleration x ₁₃ (d ² x / dt ² ) are detected and output to the control device 8. Also, from the side of the trunk lid 2, displacement ₂₁ on the actuator side, velocity x ₂₂ (dx / dt), acceleration x ₂₃ (d ² x /
dt ² ) is output to the control device 8. In the control device 8, the input signals (x ₁₁ , x ₁₂ , x ₁₃ , x ₂₁ , x
₂₂ , x ₂₃ ), x ₁₁ = x ₂₁ , x ₁₂ = x ₂₂
The control force to the actuator 7 is determined so that

Next, the operation of the muffled sound reducing apparatus will be described.

When the panels such as the trunk lid 2 and the spare tire pan 3 vibrate due to running of an automobile or the like, the spare tire pan 3 side vibrates (sensor side displacement x ₁₁ ,
The velocity x ₁₂ , the acceleration x ₁₃ ) is detected by the vibration sensor 6,
It is output to the control device 8. In addition, the actuator 7
With the actuator sensor 11 of the trunk lid 2
Side vibration state (actuator side displacement x ₂₁ , velocity x ₂₂ ,
The acceleration x ₂₃ ) is detected and this value is output to the control device 8. In the control device 8, the input signals (x ₁₁ , x ₁₂ ,
x _13, based on the _{x 21, x 22, x 23} ), always, x ₁₁ = x
The control energy (current) to the actuator 7 is determined so that ₂₁ and x ₁₂ = x ₂₂ .

When the control energy from the control device 8 is input to the coil 9, a magnetic field is generated, the movable mass 10 of the magnet moves up and down, and the inertial force of the movable mass 10 causes the movable mass 10 to move toward the trunk lid 2 side. When the reaction force is input, the trunk lid 2 side is vibrated, and this vibration is fed back by the actuator sensor 11 so as to be controlled to a predetermined vibration.

As a result, the trunk lid 2 side is vibration-controlled to a predetermined value and is vibrated in phase with the spare tire pan 3 side.

Spare tire pans 3 which are thus substantially opposed to each other
If the side and the trunk lid 2 side vibrate in the same phase, the pressure fluctuation of the air in the trunk room 1 will be reduced by the spare tire pan 3
Side and the trunk lid 2 side are always in a +/- opposite phase, and they cancel each other out to suppress the sound pressure level in the trunk room 1 to a low level and reduce the muffled sound.

Further, when the resonance frequency is located at a position about 1 Hz below the bending point of the vehicle body, the vehicle body radiation coefficient at 20 to 40 Hz becomes the lowest.

Here, the reason why the muffled noise can be reduced if the spare tire pan 3 side and the trunk lid 2 side vibrate in the same phase will be described.

The vehicle body radiation coefficient is 24 as shown in FIG.
The maximum is in the vicinity of Hz, and attention is paid to this part.

The 24 Hz mode is a mode in which two bends, the bounce of the trunk lid 2 and the bounce of the spare tire pan 3 are coupled.

In this mode, as shown in FIG.
When the value of the trunk lid support rigidity is taken on the horizontal axis and the value of the radiation coefficient is taken on the vertical axis, the spare tire pan 3 side and the trunk lid 2 side show the characteristics as shown by curves A and B, respectively. The emission coefficient peak level due to the influence exhibits a characteristic as shown by the curve C. In this case, by changing the trunk lid support rigidity, the eigenvalue of the trunk lid 2 changes, and three phases exist in each of the areas 1, 2, and 3 shown below. The black arrow indicates the Z-direction relative phase.

In the area 1, as shown by the black arrow, the spare tire pan 3 side and the trunk lid 2 side are swung in opposite phases, and the volume change is large and the sound pressure level is high.

In the region 2, the spare tire pan 3 side and the trunk lid 2 side are in phase, and since the vibration level is close, the volume change is small and the sound pressure level is low.

In the region 3, the vibration level on the side of the trunk lid 2 becomes small, and only the influence on the side of the spare tire pan 3 appears.

As can be seen from the region 2, the emission coefficient decreases when the spare tire pan 3 side and the trunk lid 2 side are in phase with each other and the vibration levels are close to each other.

Therefore, in the present invention, the trunk lid 2
Instead of changing the eigenvalue of, the actuator 7 controls the vibration of the trunk lid 2 to make the trunk lid bounce resonance frequency and the spare tire resonance frequency the same, thereby reducing the muffled noise.

With this configuration, by appropriately controlling the vibration of the trunk lid 2 and the like, the level of the muffled sound can be reliably ensured without being affected by the frequency band of the muffled sound in question and variations among the vehicles. Can be reduced.
Moreover, since the trunk lid 2 is vibrated to reduce the muffled noise in response to the vibration of the spare tire pans 3 which are substantially opposed to each other, a pair of vibrations is generated for the pair of panels 2 and 3 which are opposed to each other. Since it suffices to prepare the sensor 6, the actuator 7, and the control device 8, the number of parts is reduced as compared with the conventional arrangement in which an actuator or the like is provided for each panel.

[0034]

As described above, according to the present invention, by directly controlling the vibration of each panel,
It is possible to reliably reduce the muffled sound level without being affected by the frequency band of the muffled sound that is a problem and the variation between vehicles. Moreover, the number of control elements (sensors, actuators, control devices, etc.) is half that in the case where vibration is suppressed for each panel, which is a practically useful effect.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the outline of one embodiment of a car muffler noise reducing apparatus of the present invention.

FIG. 2 is a cross-sectional view showing an actuator of the same embodiment.

FIG. 3 is an explanatory diagram showing a vibration system of the same example.

FIG. 4 is a graph showing a relationship between a vehicle body frequency and a radiation coefficient.

FIG. 5 is a graph showing the relationship between the track lid support rigidity of the trunk lid and the like and the radiation coefficient and the like.

[Explanation of symbols] 1 trunk room (vehicle interior space) 2 trunk lid (other panel) 3 spare tire pan (one panel) 6 vibration sensor 7 actuator 8 control device

Claims (1)

[Claims] 1. A vehicle interior space is formed by a plurality of panels, and a vibration sensor for measuring a vibration state of the one panel is provided on one of the panels substantially opposite to each other, and the other panel is provided on the other panel. An actuator for controlling a vibration state of the other panel, and further, the actuator so that the signal measured by the vibration sensor is input and the other panel vibrates in phase with the one panel. A muffled noise reducing apparatus for an automobile, which is provided with a control device for controlling the above.