JP6332724B2 - Vehicle noise reduction structure - Google Patents

Description

  The present invention relates to a noise reduction structure for a vehicle.

  Patent Document 1 describes a sound insulation cover that covers the upper surface of an engine that vibrates to generate noise when operated. A vibration part consisting of a spring and mass is attached to the plane of the cover body of the sound insulation cover, and the sound insulation cover vibrates at a frequency that matches the natural frequency of the vibration part of the engine excitation frequency. The vibration part attached to the sound insulation cover vibrates and insulates the noise from the engine.

JP 2013-57709 A

  In an engine having a head cover that prevents scattering of engine oil, noise due to vibration of the head cover may be a problem. In order to prevent such noise from the head cover, if a sound insulating cover as in Patent Document 1 is provided, the weight of the vehicle and the installation space increase.

  Therefore, an object of the present invention is to provide a vehicle noise reduction structure that can reduce the noise of an engine head cover while suppressing the gravity of the vehicle and saving space.

In order to achieve the above object, the vehicle noise reduction structure of the present invention includes a head cover and a damper. The head cover is fixed to the cylinder head of the engine, covers the outer surface of the cylinder head away from the cylinder head, a plurality of fuel injection nozzle holes are formed, and surface vibrations according to the driving of the engine, A surface portion having a specific resonance frequency and a protrusion protruding from the upper surface of the surface portion are integrally provided to prevent engine oil from scattering from the outer surface of the cylinder head. The damper includes a plate member having an attachment portion fixed to the protrusion between the plurality of fuel injection nozzle holes of the head cover, a vibration portion extending from the attachment portion and facing away from the surface portion of the head cover, and vibration And a mass fixedly provided on the portion and spaced from the head cover. The resonance frequency of the damper is set to be equal to the resonance frequency of the surface portion of the head cover. The head cover and the plate member are made of the same material.

  In the above configuration, the head cover is fixed to the cylinder head of the engine, and the surface portion of the head cover is separated from the outer surface of the cylinder head. Therefore, when the engine is driven and vibration is transmitted to the head cover, The surface portion of the head cover vibrates. In addition, since the mounting part of the damper is fixed with respect to the surface part of the head cover, the vibration of the surface part excites the vibration of the damper having the mass, and the damper freely moves the tip of the vibration part opposite to the mounting part. Vibrates as an edge. Since the resonance frequency of the damper is set to be equal to the resonance frequency of the surface portion of the head cover, the damper resonates due to surface vibration of the surface portion at a specific resonance frequency or a frequency in the vicinity thereof. The resonance of the damper reduces the vibration level by dividing the surface vibration peak of the surface portion. Therefore, noise caused by vibration of the head cover can be reduced.

  In addition, noise is reduced by fixing the damper to the head cover, so that the weight of the vehicle is reduced and space is saved compared to the case where a sound insulation member such as a sound insulation cover is separately provided around the head cover. Can be achieved.

  In addition, when the resonance frequency of the head cover surface is changed due to a design change, etc., the resonance frequency of the damper is adjusted to the resonance frequency of the head cover surface by appropriately changing the shape, weight, material, etc. of the vibration part and mass. Can do.

  Further, since the damper is fixed to the head cover, the heat of the head cover is easily transmitted to the damper, and the temperature difference between the head cover and the damper is relatively unlikely to occur. For this reason, when the resonance frequency of the head cover changes due to heat, the resonance frequency of the damper is also likely to change following the change of the head cover, and a reduction in noise reduction effect due to an increase in engine temperature can be suppressed. Note that the resonance frequency of the damper can be made to follow the resonance frequency of the head cover more accurately by forming the head cover and the damper with the same material (for example, a resin material).

  The damper may be formed of a material having a function of attenuating its own vibration.

  In the above configuration, when the surface portion of the head cover vibrates at the resonance frequency or a frequency in the vicinity thereof and the damper resonates, the damper attenuates its own vibration.

  Therefore, it is possible to further reduce the vibration level of the surface vibration of the head cover and further reduce the noise of the head cover of the engine.

  ADVANTAGE OF THE INVENTION According to this invention, the noise of the head cover of an engine can be reduced, suppressing the gravity of a vehicle and achieving space saving.

It is a perspective view of the noise reduction structure concerning one embodiment of the present invention. It is principal part sectional drawing of the noise reduction structure of FIG. It is a graph which shows the vibration reduction effect by the noise reduction structure of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the vertical direction corresponds to the vertical direction in FIGS.

  As shown in FIG. 1, an engine 2 mounted on a vehicle 1 according to this embodiment includes a cylinder block (not shown), a cylinder head 3, a head cover 5, and a lubrication device (not shown), and a vehicle body frame (not shown). It is fixed to (omitted) and vibrates during driving.

  The lubricating device circulates and supplies engine oil into the engine 2. The cylinder head 3 is a metal member having a substantially rectangular parallelepiped appearance, and is disposed on the upper portion of the engine 2 and fixed to the cylinder block. A camshaft (not shown) that rotates in response to the driving of the engine 2 is accommodated in the upper part inside the cylinder head 3. The upper surface 11 of the cylinder head 3 is open, and the engine oil is scattered from the upper surface 11 by the rotation of the camshaft.

  As shown in FIGS. 1 and 2, the head cover 5 is a flat resin member and covers the upper surface 11 of the cylinder head 3 to prevent the engine oil from scattering from the upper surface 11. The damper 6 is fixed to the upper surface 18 of the head cover 5, and the head cover 5 and the damper 6 constitute the noise reduction structure 4 of the present embodiment.

  The head cover 5 includes a surface portion 13 in the central region, a plurality of fixing portions 12 disposed on the outer periphery of the surface portion 13, and protrusions 15 protruding from the upper surface of the surface portion 13, which are integrally formed of a resin material. ing. A plurality of (four in this embodiment) fuel injection nozzle holes 14 are formed in the surface portion 13 so as to be spaced apart from each other and arranged in a straight line.

  Each fixing portion 12 is formed with a head cover bolt insertion hole 16 penetrating vertically. The head cover 5 is fastened and fixed to the outer edge portion 11a of the upper surface 11 of the cylinder head 3 via a head cover gasket (not shown) by a head cover bolt (not shown) inserted through the head cover bolt insertion hole 16. The head cover 5 may be fixed to the cylinder head 3 by a method other than fastening with bolts or the like.

  The surface portion 13 is separated from the cylinder head 3 and covers the upper surface 11 in a state where the head cover 5 is fixed to the cylinder head 3. The surface portion 13 has a specific resonance frequency (about 400 Hz in this embodiment), and performs surface vibration in accordance with the driving of the engine 2.

  The four fuel injection nozzle holes 14 are arranged at equal intervals along the longitudinal direction of the head cover 5 at the approximate center in the width direction of the surface portion 13, and downward from the periphery of each fuel injection nozzle hole 14 on the lower surface of the surface portion 13. An extending cylindrical wall 17 is integrally formed. The protrusion 15 is disposed between the four fuel injection nozzle holes 14. That is, the protrusion 15 is disposed in the central portion of the surface portion 13 where surface vibration is relatively large.

  Each damper 6 includes a rectangular plate-like plate member 20 that is fixed to the protrusion 15 of the head cover 5 in a cantilever shape, and a mass 21 that is fixedly provided on the plate member 20. The resonance frequency of the damper 6 is set to be equal to the resonance frequency (about 400 Hz) of the surface portion 13 of the head cover 5.

  The plate member 20 has a flat plate shape integrally including a mounting portion 23 fixed to the upper surface 15a of the protruding portion 15 and a vibration portion 24 extending from the mounting portion 23, and has a function of attenuating its own vibration. Is formed by. A damper bolt insertion hole (not shown) penetrating vertically is formed in the mounting portion 23, and the plate member 20 is fastened and fixed to the upper surface 15 a of the protrusion portion 15 of the head cover 5 by a damper bolt 22 that passes through the damper bolt insertion hole. Yes. The plate member 20 may be fixed to the head cover 5 by a method other than fastening with bolts or the like.

  In a state where the attachment portion 23 is fixed to the projection portion 15, the vibration portion 24 is opposed to be separated from the surface portion 13 of the head cover 5, and the tip 24 c of the vibration portion 24 located on the opposite side of the attachment portion 23 is a free end. .

  The mass 21 is a rectangular plate-shaped metal member having a desired mass, and is fixed to the tip 24c side of the vibration unit 24 in a state where the lower surface 26 of the mass 21 and the upper surface 24a of the vibration unit 24 are in surface contact with each other. 5 apart.

  According to the present embodiment, the head cover 5 is fixed to the cylinder head 3 by the plurality of fixing portions 12 on the outer periphery of the surface portion 13, and the surface portion 13 is not fixed to the cylinder head 3 and is separated from the upper surface 11 thereof. For this reason, when the engine 2 is driven and the vibration is transmitted to the head cover 5, the surface portion 13 of the head cover 5 vibrates in accordance with the driving of the engine 2. Further, since the attachment portion 23 of the damper 6 is fixed to the surface portion 13 of the head cover 5, the vibration of the surface portion 13 excites vibration of the damper 6 having the mass 21, and the damper 6 moves the tip 24 c of the vibration portion 24. Vibrates up and down as a free end. Since the resonance frequency of the damper 6 is set to be equal to the resonance frequency (about 400 Hz) of the surface portion 13 of the head cover 5, the surface portion 13 vibrates at a specific resonance frequency (about 400 Hz) or a frequency in the vicinity thereof. Therefore, the damper 6 resonates, and the resonance of the damper 6 divides the surface vibration peak of the surface portion 13 to lower the vibration level. Therefore, the noise of the head cover 5 of the engine 2 can be reduced.

  Here, the vibration reduction effect of the head cover 5 by the damper 6 will be described in detail with reference to FIG.

  3 shows the frequency applied to the surface portion 13 when the damper 6 is attached to the surface portion 13 of the head cover 5 (shown by a solid line in the drawing) and when the damper 6 is not attached (shown by a dotted line in the drawing). It is the result of measuring the vibration level of the surface portion 13 while changing. As is clear from FIG. 3, when the damper 6 is not attached to the surface portion 13, a vibration level peak occurs in the vicinity of the resonance frequency (about 400 Hz) of the surface portion 13. On the other hand, when the damper 6 is attached to the surface portion 13, the peak of the vibration level of the surface portion 13 is divided in the vicinity of the resonance frequency (about 400 Hz) of the surface portion 13, thereby reducing the vibration level. I understand.

  Further, since the noise is reduced by fixing the damper 6 to the head cover 5, the cost and weight of the vehicle 1 are suppressed compared to the case where a sound insulation member such as a sound insulation cover is separately provided around the head cover 5. In addition, space saving can be achieved.

  In addition, when the resonance frequency of the surface portion 13 of the head cover 5 is changed due to a design change or the like, the resonance frequency of the damper 6 is changed to the surface portion of the head cover 5 by appropriately changing the shape, weight, material, or the like of the plate member 20 or the mass 21. It can be adjusted to 13 resonance frequencies.

  Further, since the damper 6 is fixed to the head cover 5, the heat of the head cover 5 is easily transmitted to the damper 6, and the temperature difference between the head cover 5 and the damper 6 is relatively unlikely to occur. For this reason, when the resonance frequency of the head cover 5 is changed by heat, the resonance frequency of the damper 6 is also likely to change following the change of the head cover 5 and suppresses a reduction in noise reduction effect due to the temperature rise of the engine 2. be able to. Further, since the head cover 5 and the plate member 20 of the damper 6 are made of the same material (resin material), the resonance frequency of the damper 6 can be made to follow the resonance frequency of the head cover 5 more accurately.

  Further, since the plate member 20 of the damper 6 has a function of attenuating its own vibration, the plate member of the damper 6 is resonated when the surface portion 13 of the head cover 5 vibrates at the resonance frequency or a frequency in the vicinity thereof and the damper 6 resonates. 20 attenuates its own vibration. Therefore, the vibration level of the surface vibration of the surface portion 13 of the head cover 5 can be further reduced, and the noise of the head cover 5 of the engine 2 can be further reduced.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the discussion and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it is needless to say that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

  For example, the material of the plate member 20 of the damper 6 is arbitrary, and is not limited to a resin material having a function of attenuating its own vibration. A material that does not have a function of damping vibration may be used. The material of the head cover 5 is also arbitrary, and is not limited to a resin material, and may be a metal material, for example.

  The damper 6 may be fixed to the lower surface 25 instead of the upper surface 18 of the head cover 5. Instead of the plate-like plate member 20, a member having another shape (for example, a rod shape) may be used. The mass 21 may be fixed to the lower surface 24 b instead of the upper surface 24 a of the vibration unit 24, and the mass 21 may be embedded in the vibration unit 24. The shape of the mass 21 is arbitrary, and may be, for example, a rectangular parallelepiped shape or a cylindrical shape. The plate member 20 and the mass 21 may be made of the same material, or the plate member 20 and the mass 21 may be integrally formed.

  Moreover, the aspect which fixes the damper 6 to the head cover 5, and the number of the dampers 6 are also arbitrary. For example, the protrusion 15 of the head cover 5 is omitted, the mounting portion of the plate member 20 of the damper 6 is bent in an L shape from the vibration portion 24, and the vibration portion 24 is spaced apart from the surface portion 13 so as to face the mounting portion. The front end portion may be fixed to the surface portion 13 of the head cover 5. A plurality of dampers 6 may be provided on the head cover 5.

  The present invention is widely applicable as a vehicle noise reduction structure.

1: Vehicle 2: Engine 3: Cylinder head 4: Noise reduction structure 5: Head cover 6: Damper 12: Fixed portion 13: Surface portion 14: Fuel injection nozzle hole 15: Projection portion 20: Plate member 21: Mass 23: Mounting portion 24 : Vibration part

Claims (2)

A fixed portion fixed to the cylinder head of the engine, and an outer surface of the cylinder head that is separated from the cylinder head and covers the outer surface of the cylinder head. A head cover integrally having a surface portion having a specific resonance frequency and a protrusion protruding from the upper surface of the surface portion, and preventing scattering of engine oil from the outer surface of the cylinder head;
A plate member having a mounting portion fixed to the protrusion between the plurality of fuel injection nozzle holes of the head cover, and a vibrating portion extending from the mounting portion and facing away from the surface portion of the head cover. And a damper that is fixedly provided on the vibration part and is spaced apart from the head cover, and a damper whose resonance frequency is set to be equal to the resonance frequency of the surface part of the head cover ,
The vehicle head noise reduction structure according to claim 1, wherein the head cover and the plate member are made of the same material . The vehicle noise reduction structure according to claim 1,
The vehicle noise reduction structure, wherein the damper is made of a material having a function of attenuating its own vibration.

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