Collision noise reduction device

Abstract

It reduces residual noise from collisions between objects. [Solution] The collision noise reduction device comprises a base, a buffer, and a movable part having a movable member that collides with the base via the buffer. The frequency at which the minimum point of the frequency components of the reaction force that the movable member receives from the buffer when the base and the movable member collide is determined is (f 0b ) approximately coincides with the natural frequency (f1) of the movable member.

Description

Technical Field

[0001] This disclosure relates to a collision sound reduction device.

Background Art

[0002] As an example of a device for reducing the collision sound that occurs when objects collide with each other, Japanese Patent Application Laid-Open No. 10-184729 (Patent Document 1) discloses an electromagnetic clutch capable of reducing the collision sound between metals. This electromagnetic clutch is provided with a plurality of rubbers arranged in the circumferential direction on the collision surface, and by making the reaction forces of these plurality of rubbers non-uniform, the collision time between metals is lengthened to reduce the collision sound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, the collision sound between objects can be divided into two types. One is an instantaneous sound (hereinafter also referred to as "impact pulse sound") that occurs while an object is receiving the force due to the collision. The other is a sound (hereinafter also referred to as "residual sound") that occurs when the object vibrates in damped oscillation at its natural frequency after the object has stopped receiving the force due to the collision. In order to reduce the collision sound, it is required to reduce both of these two types of sounds. However, Patent Document 1 only aims to reduce the impact pulse sound among these, and does not consider reducing the residual sound.

[0005] This disclosure has been made to solve such problems, and its object is to reduce the residual sound among the collision sounds between objects.

Means for Solving the Problems

[0006] The collision noise reduction device according to this disclosure comprises a base, a buffer, and a movable part having a movable member that collides with the base via the buffer. The frequency at which the minimum point of the frequency components of the reaction force that the base or the movable member receives from the buffer when the base and the movable member collide is substantially coincides with the natural frequency of the base or the movable member. [Effects of the Invention]

[0007] According to this disclosure, residual noise from collisions between objects can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the configuration of a collision noise reduction device. [Figure 2] The diagram shows the movable member not in contact with the base. [Figure 3] The image shows the movable member in contact with the base. [Figure 4] An example of the acceleration of vibrations generated in a movable member due to a collision is shown. [Figure 5] An example of how the force acting on a movable member changes over time is shown. [Figure 6] The frequency components of the force acting on the movable member are shown. [Figure 7] An example of the time evolution of the reaction force in this disclosure is shown. [Figure 8] The frequency components of the reaction force in this disclosure are shown. [Figure 9] The situation in which the movable member collides with the base is shown by modeling it using a spring-mass system. [Modes for carrying out the invention]

[0009] This embodiment will be described in detail below with reference to the drawings. In the following description, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated.

[0010] [Configuration of the collision noise reduction device] Figure 1 is a schematic diagram showing the configuration of the collision noise reduction device 1 according to this embodiment. The collision noise reduction device 1 is, for example, a device that houses analytical instruments inside.

[0011] The collision noise reduction device 1 comprises a base 10, a buffer 20, a movable part 60, and a catch fitting (base side) 40.

[0012] The base 10 supports the movable part 60, which will be described later, so that the position of the movable part 60 is variable. In Figure 1, the base 10 is a hollow rectangular parallelepiped, but it is not limited to this shape.

[0013] The movable part 60 comprises a movable member 30 and a catch fitting (movable side) 50. When the movable part 60 is displaced toward the base 10, the movable member 30 collides with the base 10 via a buffer part 20, which will be described later. In Figure 1, for example, the movable member 30 is flat and functions as a door that opens and closes relative to the base 10. However, it may have a shape other than a flat plate, and it does not have to function as a door.

[0014] The catch fitting (base side) 40 is attached to the base 10. The catch fitting (base side) 40 and the catch fitting (movable side) 50 are configured to be connectable. When the catch fitting (base side) 40 and the catch fitting (movable side) 50 are connected, the movable part 60 is fixed to the base 10 in a predetermined position.

[0015] The buffer portion 20 is positioned between the movable member 30 and the base 10 when the movable member 30 collides with the base 10. The material of the buffer portion 20 is generally an elastically deformable material such as rubber. In Figure 1, the buffer portion 20 is composed of two buffer members 21 and 22, but the number of buffer members is not limited to two; it may be one or three or more. Also, in Figure 1, the buffer portion 20 is attached to the base 10, but it may also be attached to the movable member 30.

[0016] When the movable member 30 collides with the base 10, the cushioning section 20 elastically deforms from its initial shape and returns to its initial shape. Figure 2 shows the state when the movable member 30 is not colliding with the base 10. Since there is no collision, the cushioning members 21 and 22 that make up the cushioning section 20 are not elastically deformed, i.e., they are in their initial shape. Figure 3 shows the state when the movable member 30 is colliding with the base 10. Since there is a collision, the cushioning members 21 and 22 that make up the cushioning section 20 are elastically deformed.

[0017] [Reducing residual noise] A collision sound is generated when the movable member 30 and the base 10 collide. The collision sound is generated by the vibration of at least one of the movable member 30 and the base 10. For example, as in the collision sound reduction device 1, when the base 10 is a hollow rectangular parallelepiped and the movable member 30 is a flat plate, the movable member 30 vibrates more, and a louder collision sound is generated from the movable member 30. However, depending on the shape and structure of the movable member 30 and the base 10, the base 10 may vibrate more and a louder collision sound may be generated from the base 10. The following describes the case in which a louder collision sound is generated from the movable member 30.

[0018] Collision sounds generated when objects collide, such as the collision between the movable member 30 and the base 10, are generally divided into impact pulse sounds and residual sounds, as described above. Figure 4 shows an example of the time change of the acceleration of vibrations generated in the movable member 30 due to the collision. In Figure 4, section A is the time when the movable member 30 is subjected to the force due to the collision. Impact pulse sounds are generated by the vibrations that occur in section A. Section B is the time when damped vibrations occur at the natural frequency of the movable member 30 after the movable member 30 is no longer subjected to the force due to the collision. Residual sounds are generated by the damped vibrations that occur in section B.

[0019] Since the residual sound is the sound generated by damped vibration, the greater the acceleration of the damped vibration, the greater the residual sound. Also, since the damped vibration is the vibration at the natural frequency after receiving the force due to the collision, the greater the component of the natural frequency among the frequency components of the force due to the collision, the greater the acceleration of the damped vibration. That is, the greater the component of the natural frequency among the frequency components of the force due to the collision, the greater the residual sound.

[0020] The frequency component of the force due to the collision is such that the shorter the time (hereinafter also referred to as the "reaction force time") during which the object receives the force due to the collision, the greater the minimum frequency f 01 which is known to be.

[0021] FIG. 5 shows an example of the time change of the force received by the movable member 30 due to the collision. FIG. 6 shows the frequency components of the force received by the movable member 30 shown in FIG. 5 due to the collision. As shown in FIG. 6, there are a plurality of frequencies (hereinafter also referred to as "minimum frequencies") f0 at which the magnitude of the frequency component becomes minimum. Let the smallest minimum frequency among the plurality of minimum frequencies f0 be f 01 and the next smallest minimum frequency be f 02 Let it be. In the range from frequency 0 to f 01 the magnitude of the frequency component monotonically decreases. Let the magnitude of the frequency component at frequency 0 be A 01 Let it be. In the range from frequency f 01 to f 02 the magnitude of the frequency component increases, reaches a peak, and then decreases. Let the magnitude of the frequency component at this peak be A 02 Let it be. At this time, the magnitude of the frequency component A 02 is smaller than the magnitude of the frequency component A 01 In the range from frequency f 02 to the next smallest minimum frequency as well, similarly, it increases, reaches a peak, and then decreases. The magnitude of the frequency component at this peak is smaller than the magnitude of the frequency component A 02 This is repeated for subsequent frequencies.

[0022] In FIG. 6, the shorter the reaction force time shown in FIG. 5, the greater the minimum frequency f 01The frequency becomes larger. Let f1 be the natural frequency of the movable member 30. The minimum frequency f 01 If the frequency is sufficiently larger than the natural frequency f1, the component of the force that the movable member 30 experiences due to the collision will have a higher frequency component at the natural frequency f1. As a result, the acceleration of the damped vibration of the movable member 30 will increase, and the residual sound will increase.

[0023] Furthermore, in Figure 6, the minimum frequency f 01 This shows the case where the natural frequency f is greater than the natural frequency f 01 Even if the natural frequency f1 is smaller, residual sound may still occur. Specifically, for example, at a very small frequency f 01 and extremely small frequency f 02 Between these points, the frequency components are relatively large, so if a natural frequency f1 exists, a certain degree of residual sound will be generated.

[0024] Here, the force that the movable member 30 receives due to the collision is the force that the movable member 30 receives from the cushioning part 20 while the cushioning part 20 is elastically deforming, and therefore it is the reaction force that the movable member 30 receives from the cushioning part 20.

[0025] In other words, the frequency components of the reaction force that the movable member 30 receives from the buffer part 20 have multiple minimum frequencies f0, and the smallest of these minimum frequencies f 01 However, if the frequency is significantly larger than the natural frequency f1 of the movable member 30, a large residual sound will be generated from the movable member 30. Also, the minimum frequency f 01 However, even if it is smaller than the natural frequency f1 of the movable member 30, if the natural frequency f1 lies between adjacent minimum frequencies among multiple minimum frequencies f0, a certain degree of residual sound will be generated.

[0026] In view of these problems, in the collision noise reduction device 1 according to this embodiment, the spring constant k (described later) of the buffer 20 is adjusted so that one of several minimum frequencies f0 of the reaction force that the movable member 30 receives from the buffer 20 substantially coincides with the natural frequency f1 of the movable member 30. This makes it possible to reduce the residual sound among the collision noise (between objects) between the base 10 and the movable member 30.

[0027] Specifically, by adjusting the spring constant k of the buffer section 20, the time during which a reaction force from the buffer section 20 is applied to the movable member 30 (hereinafter referred to as "reaction force time t") can be controlled. p Adjust the reaction force time t (also known as "..."). p This is adjusted so that one of the minimum frequencies f0 approximately coincides with the natural frequency f1 of the movable member 30. As a result, the magnitude of the natural frequency f1 component among the frequency components of the reaction force becomes minimal. Consequently, the acceleration of the damped vibration of the movable member 30 is reduced, and residual sound can be reduced.

[0028] Here, "approximately identical" is not limited to the fact that one of the minimum frequencies f0 perfectly matches the natural frequency f1. If one of the minimum frequencies f0 is in the vicinity of the natural frequency f1, and the magnitude of the component at natural frequency f1 is approximately minimal, then it is considered an approximate match.

[0029] This section describes a method for adjusting the spring constant k of the buffer section 20 so that one of the minimum frequencies f0 approximately matches the natural frequency f1 of the movable member 30. To do this, first, the reaction force time t p This explains the relationship between the minimum frequency f0.

[0030] In this embodiment, when the base 10 and the movable member 30 collide, the buffer portion 20 elastically deforms from its initial shape and returns to its initial shape. That is, the reaction force that the movable member 30 receives from the buffer portion 20 changes over time in a semi-sinusoidal manner.

[0031] Here, if the force acting on an object changes over time in a semisine wave manner, the minimum frequency f of the frequency component of that force is... 01 and reaction time t p The relationship between these two factors is known to be approximated by equation (1).

[0032] f 01 = 1.5 / t p ...(1) Note that among the multiple minimum frequencies f0, the minimum frequency f 01 For frequencies other than those mentioned above, the reaction force time t pAlthough a relationship exists, it will be omitted here. That is, for each of the multiple minimum frequencies f0, the reaction force time t p There are several equations that approximate the relationship with . From here on, the minimum frequency f 01 We will now explain the case where equation (1) is used for the following.

[0033] In equation (1), the minimum frequency f 01 Substituting the natural frequency f1 of the movable member 30 into equation (2), we obtain equation (2).

[0034] f1 = 1.5 / t pb ...(2) The value of t can be found from equation (2). pb This is called the target reaction time. Reaction time t p Adjust the target reaction force time t pb If you match it, the smallest frequency f 01 This will approximately coincide with the natural frequency f1 of the movable member 30.

[0035] Figure 7 shows the reaction force time t. p Target reaction force time t pb An example of the time variation of the reaction force (hereinafter also referred to as "the reaction force of this disclosure") when using a buffer 20 whose spring constant k has been adjusted to match the given spring constant k is shown. The time variation of the reaction force of this disclosure is shown by a solid line. As a comparative example, the time variation of the reaction force (hereinafter also referred to as "the reaction force of the comparative example") when using a buffer 20 whose spring constant k has not been adjusted is shown by a dashed line. Both the reaction force of this disclosure and the reaction force of the comparative example are assumed to change in a semisinusoidal manner over time. Furthermore, as shown in Figure 7, the reaction force time t of the reaction force of the comparative example pa The target reaction time t pb It is considered sufficiently short compared to [the other].

[0036] Figure 8 shows the frequency components of the reaction force of this disclosure. The frequency components of the reaction force of this disclosure shown in Figure 7 are shown by solid lines. As a comparative example, the frequency components of the reaction force of the comparative example shown in Figure 7 are shown by dashed lines. Among the multiple minimum frequencies f0 of the reaction force of this disclosure, the smallest minimum frequency is f. 0b Let f be the smallest minimum frequency among the multiple minimum frequencies f0 of the reaction force in the comparative example.0a The reaction time t of the reaction force in this disclosure. p The target reaction time t pb Because it matches, the smallest frequency f 0b This approximately coincides with the natural frequency f1 of the movable member 30. As a result, the magnitude of the component with the natural frequency f1 among the frequency components of the reaction force that the movable member 30 receives from the buffer part 20 is minimized. On the other hand, the reaction force time t of the comparative example pa The target reaction time t pb Because it is sufficiently shorter compared to, the extremely small frequency f 0a f is an extremely small frequency 0b It is significantly larger, that is, significantly larger than the natural frequency f1. Therefore, the magnitude of the component at natural frequency f1 becomes larger.

[0037] Thus, according to equation (2), the target reaction time t pb Find the reaction force time t p Adjust the target reaction force time t pb If you match it, the smallest frequency f 0b This approximately coincides with the natural frequency f1 of the movable member 30.

[0038] Next, the reaction force time t p Adjust the target reaction force time t pb A method for adjusting the spring constant k of the buffer section 20 to match this will be explained.

[0039] Reaction force time t p Considering the displacement of the movable member 30 during this time, the movable member 30 moves from a position where it contacts the initial shape of the buffer portion 20 to a position where the buffer portion 20 is most compressed, against the reaction force from the buffer portion 20, and then returns to a position where it contacts the initial shape of the buffer portion 20 again due to the reaction force from the buffer portion 20. During this time, the only force acting on the movable member 30 is the reaction force from the buffer portion 20, so this displacement of the movable member 30 is due to free vibration. Furthermore, this displacement is the displacement on only one side from the center position out of the displacement for one period of free vibration. Therefore, the reaction force time t p This corresponds to half the period of free vibration of the movable member 30.

[0040] A method for determining the period of free vibration of the movable member 30 is described. The buffer 20 undergoes elastic deformation, and the change in reaction force per unit displacement during elastic deformation is constant. The change in reaction force per unit displacement in the collision direction is denoted as the spring constant k of the buffer 20, and the mass of the movable part 60 is denoted as m. Figure 9 shows a model of the situation when the movable member 30 collides with the base 10 using a spring-mass system. In Figure 9, the buffer 20 is modeled as a spring 70, and the movable part 60 is modeled as an object 80. Figure 9(a) shows the situation before the collision, where the length of the spring 70 is its free length L0, and the velocity of the movable part 60 is v0. Figure 9(b) shows the situation after the collision when the spring 70 is most compressed, and the maximum compressed length is x max That is the case.

[0041] In this case, the mechanical energy in free vibration is given by equation (3) from the law of conservation of energy.

[0042]

number

[0043] Here, x is the displacement of the movable part, and v is the velocity of the movable part. In equation (3), v is the first derivative with respect to x, so it can be rearranged to be expressed as equation (4).

[0044]

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[0045] Taking the time derivative of both sides of equation (4), we get equation (5).

[0046]

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[0047] Assuming the first derivative with respect to x is non-zero, dividing both sides of equation (5) by the first derivative with respect to x and rearranging the equation gives us equation (6).

[0048]

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[0049] Equation (6) represents free oscillation with angular frequency Ω (equation (7)), that is, period T (equation (8)).

[0050]

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[0051]

number

[0052] Half of the period T of free oscillation is the reaction time t. p This is expressed by equation (9).

[0053]

number

[0054] The reaction time t shown in equation (9) p However, the target reaction force time t for the movable member 30 pb The spring constant k of the buffer section 20 is adjusted in advance so that this occurs. This results in a reaction force time t p Target reaction time t pb This matches. As a result, the minimum frequency f of the reaction force that the movable member 30 receives from the buffer part 20 is 0b This can be made to approximately match the natural frequency f1 of the movable member 30.

[0055] In the above embodiment, the buffer section 20 includes two buffer members 21 and 22. In this case, the two spring constants of the two buffer members 21 and 22 are set such that their combined value equals the spring constant k of the buffer section 20.

[0056] This allows the cushioning members 21 and 22 to be attached at two positions, so that the reaction force from the cushioning members 21 and 22 is applied to two positions on the movable member 30. As a result, residual noise can be reduced while preventing the movable member 30 from tilting during a collision.

[0057] Furthermore, in the above embodiment, the buffer portion 20 is attached to the base portion 10. If the buffer portion 20 were attached to the movable member 30 instead of the base portion 10, inertial force and centrifugal force would be applied to the buffer portion 20 due to the displacement of the movable portion 60. By attaching it to the base portion 10, inertial force and centrifugal force are not applied to the buffer portion 20, making it less likely for the buffer portion 20 to fall off.

[0058] Furthermore, in the above embodiment, the cushioning portion 20 is made of rubber. In this case, the spring constant k of the cushioning portion 20 can be easily adjusted by adjusting the type and dimensions of the rubber.

[0059] Furthermore, in the above embodiment, the movable member 30 is a metal door, and one of the multiple minimum frequencies f0 substantially coincides with the natural frequency of the metal door. This makes it possible to reduce the residual sound of the metal door.

[0060] An example of a specific adjustment method for the cushioning members 21 and 22 is shown. Assume the mass m of the movable part 60 is 0.53 kg, and the movable member 30 is made of metal with a natural frequency of 416 Hz. From equations (2) and (9), the spring constant k of the buffer part 20 is found to be 1.61 × 10^6 N / m. The buffer part 20 is made of rubber (natural rubber), and in this case, the Young's modulus of the buffer part 20 is 2 MPa. The buffer part 20 consists of two buffer members 21 and 22 of the same dimensions. The combined value of the two spring constants of these two buffer members 21 and 22 is the spring constant k of the buffer part. Then, each of the buffer members 21 and 22 will have, for example, a width of 10 mm, a length of 35 mm, and a thickness of 3 mm. As a result, the minimum frequency f of the frequency component of the reaction force that the movable member 30 receives from this buffer part 20 is... 0b However, this approximately coincides with the natural frequency of the movable member 30, which is 416 Hz. As a result, residual sound from the movable member 30 can be reduced.

[0061] In this embodiment, a method for reducing residual noise generated from the movable member 30 when a louder collision noise is generated from the movable member 30 has been described, but the method for reducing residual noise generated from the base 10 when a louder collision noise is generated from the base 10 is similar. If a louder collision noise is generated from the base 10, the spring constant k of the buffer 20 is adjusted based on the natural frequency of the base 10.

[0062] Furthermore, in this embodiment, the smallest minimum frequency f among the multiple minimum frequencies f0 is 0b The frequency was set to approximately match the natural frequency f1 of the movable member 30, but the smallest minimum frequency f 0b It is not limited to this. In that case, the minimum frequency f 0b Reaction force time t for minimum frequencies f0 other than those mentioned above. p The relationship between these two is used.

[0063] [Pattern] Those skilled in the art will understand that the embodiments and their modifications described above are specific examples of the following embodiments.

[0064] (Article 1) A collision noise reduction device according to one embodiment comprises a base, a buffer, and a movable part having a movable member that collides with the base via the buffer. The frequency at which the minimum point of the frequency components of the reaction force that the base or the movable member receives from the buffer when the base and the movable member collide is substantially coincides with the natural frequency of the base or the movable member.

[0065] According to the collision noise reduction device described in paragraph 1, the frequency at which the minimum point occurs among the frequency components of the reaction force that the base or movable member receives from the buffer when the base and movable member collide approximately coincides with the natural frequency of the base or movable member. As a result, the amplitude of the damped vibration of the base or movable member can be reduced compared to the case where the frequency at which the minimum point occurs does not approximately coincide with the natural frequency (especially when the frequency at which the minimum point occurs is greater than the natural frequency). Consequently, the residual sound among the collision noises between the base and the movable member (between objects) can be reduced.

[0066] (Section 2) In the collision noise reduction device described in Section 1, the buffer unit elastically deforms from its initial shape when the base and the movable member collide, and returns to its initial shape. The frequency at which it takes a minimum point changes according to the reaction force time, which is the time the base or the movable member receives a reaction force. The change in reaction force per unit displacement during the elastic deformation of the buffer unit is defined as the spring constant of the buffer unit, and the reaction force time at which the frequency at which it takes a minimum point approximately coincides with the natural frequency is defined as the target reaction force time. The spring constant of the buffer unit is pre-adjusted so that the reaction force time becomes the target reaction force time.

[0067] According to the collision noise reduction device described in paragraph 2, the spring constant of the buffer section is pre-adjusted so that the reaction force time becomes the target reaction force time. The target reaction force time is the reaction force time at which the frequency at which the minimum point occurs approximately coincides with the natural frequency. By adjusting the spring constant in this way, the frequency at which the minimum point occurs can be made to approximately coincide with the natural frequency.

[0068] (Section 3) In the collision noise reduction device described in Section 2, assuming that the movable part undergoes free vibration during a collision, the period of free vibration changes according to the spring constant of the buffer and the mass of the movable part. The spring constant of the buffer is pre-adjusted so that half of the period of free vibration becomes the target reaction force time.

[0069] According to the collision noise reduction device described in paragraph 3, the spring constant of the buffer is pre-adjusted so that the target reaction force time is half the period of free vibration. Here, when the movable part vibrates freely during a collision, the reaction force time is half the period of free vibration. By adjusting the spring constant in this way, the reaction force time can be made to be the target reaction force time.

[0070] (Article 4) In the collision noise reduction device described in Article 3, the buffer section includes a plurality of buffer members, and the spring constant of the buffer section is the combined value of the plurality of spring constants that each of the plurality of buffer members has.

[0071] According to the collision noise reduction device described in paragraph 4, the buffer section includes multiple buffer members, allowing the buffer members to be attached at multiple positions so that reaction forces are applied to multiple positions on the movable member. As a result, it is possible to reduce residual noise from collisions between objects while preventing the movable member from tilting during a collision.

[0072] (Article 5) In the collision noise reduction device described in Article 1, the buffer is attached to the base.

[0073] According to the collision noise reduction device described in paragraph 5, by attaching the cushioning part to the base, it is less likely to fall off compared to when it is attached to a movable member.

[0074] (Article 6) In the collision noise reduction device described in Article 1, the cushioning part is made of rubber. According to the collision noise reduction device described in paragraph 6, since the cushioning part is made of rubber, the spring constant of the cushioning part can be easily adjusted by adjusting the type and dimensions of the rubber.

[0075] (Section 7) In the collision noise reduction device described in Section 1, the movable member is a metal door, and the frequency at which the minimum point occurs is approximately the natural frequency of the metal door.

[0076] According to the collision noise reduction device described in paragraph 7, the frequency at which the minimum point occurs approximately coincides with the natural frequency of the metal door, thereby reducing the residual noise of the metal door.

[0077] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0078] 1. Collision noise reduction device, 10. Base, 20. Cushioning part, 21, 22. Cushioning members, 30. Movable member, 40. Catch fitting (base side), 50. Catch fitting (movable side), 60. Movable part, 70. Spring, 80. Object, A, B section, A 01 ,A 02 The magnitude of the frequency component, L0 free length, T free vibration period, f0, f 01 ,f 02 ,f 0a ,f 0b Minimum frequency, f1 natural frequency, k spring constant, m mass, t pa Reaction force time, t pb Target reaction force time, v0 velocity, x max Maximum compression length.

Claims

1. The base and, The buffer part, The base comprises a movable part having a movable member that collides with the cushioning part, A collision noise reduction device wherein the frequency at which the minimum point of the frequency components of the reaction force that the base or the movable member receives from the buffer when the base and the movable member collide substantially coincides with the natural frequency of the base or the movable member.

2. The buffer portion, when the base portion and the movable member collide, elastically deforms from its initial shape and returns to its initial shape. The frequency at which the minimum point occurs changes according to the reaction force time, which is the time that the base or the movable member receives the reaction force. The collision noise reduction device according to claim 1, wherein the amount of change in reaction force per unit displacement in the elastic deformation of the buffer is defined as the spring constant of the buffer, and the reaction force time when the frequency at which the minimum point occurs substantially coincides with the natural frequency is defined as the target reaction force time, and the spring constant of the buffer is pre-adjusted so that the reaction force time becomes the target reaction force time.

3. Assuming that the movable part undergoes free vibration during the collision, the period of the free vibration changes according to the spring constant of the buffer and the mass of the movable part. The collision noise reduction device according to claim 2, wherein the spring constant of the buffer is pre-adjusted so that half of the period of the free vibration is the target reaction force time.

4. The cushioning portion includes a plurality of cushioning members, The collision noise reduction device according to claim 3, wherein the spring constant of the buffer portion is a value obtained by combining the multiple spring constants that each of the multiple buffer members has.

5. The collision noise reduction device according to claim 1, wherein the buffer portion is attached to the base portion.

6. The collision noise reduction device according to claim 1, wherein the cushioning part is made of rubber.

7. The aforementioned movable member is a metal door, The collision noise reduction device according to claim 1, wherein the frequency at which the minimum point occurs substantially coincides with the natural frequency of the metal door.

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