JP2014046876A - Spare tire fitting structure - Google Patents

Abstract

A spare tire mounting structure that reduces vertical vibrations of a floor panel and reduces the noise of a vehicle interior is provided.
In a spare tire mounting structure in which a central portion 5a of a spare tire 2 is fixed to a floor panel 1 of a vehicle by a fixing member 6, the fixing member 6 is disposed between the spare tire 2 and the floor panel 1 between the front and rear of the vehicle. The low-rigidity portion 9 is lower in rigidity in the vehicle width direction than in the direction. Only the roll resonance frequency of the spare tire 2 can be lowered to bring the roll resonance frequency closer to the bounce resonance frequency. In roll resonance, both end portions 2a, 2b of the spare tire 2 facing each other centering on the center portion 5a of the spare tire 2 vibrate in opposite phases in the vehicle vertical direction, so that both ends 2a, 2b of the spare tire 2 in the vehicle vertical direction are bounced. Vibration can be reduced and vertical vibration of the floor panel 1 can be suppressed.
[Selection] Figure 1

Description

  The present invention relates to a structure for attaching a spare tire to a floor panel of a vehicle.

  In a vehicle including an internal combustion engine as a driving force source, it is known that the vehicle resonates due to vibrations caused by repeated fluctuations in torque output from the internal combustion engine, vibrations input from the road surface, etc., resulting in a booming noise in the passenger compartment. ing. In general, the sound of the booming noise is a relatively low frequency band sound generated in the passenger compartment when the engine is rotating at a low rotational speed of about idling speed, that is, a so-called idle booming sound area. It is recognized as a sound that impairs the ride comfort. The frequency of the idle muffled sound region includes the resonance frequency of the floor panel, which is a cause of vehicle interior resonance, and the floor panel generates sound due to the vertical vibration of the floor panel, which tends to be a muffled sound in the vehicle interior. An example of a spare tire mounting structure is described in Patent Literature 1 as a measure for reducing such a loud noise caused by floor panel vibration.

  The spare tire mounting structure described in Patent Document 1 includes a bracket for fixing a tire center portion with a carrier screw and a cushion on which a tire portion side surface is placed around the rear floor panel of an automobile having a back door. It is arranged. In addition, a floor reinforcement for reinforcing the rear floor panel is provided, and the resonance frequency of the rear floor panel, which is lower than the bending resonance frequency of the body with respect to the input vibration from the road surface, is set higher than the bending resonance frequency of the body when the spare tire is attached. In addition, the spring constant of the cushion is set. As a result, the volume change of the passenger compartment can be reduced by the vibration of the rear floor panel in response to the road surface input, and the level of the muffled sound can be reduced.

  Further, a spare tire mounting structure described in Patent Document 2 includes a flat rear floor panel on which a spare tire mounted on a vehicle is installed, a center portion of a wheel of a spare ear, a vehicle body front side from the center portion, and Fixing means for fixing a peripheral portion of the wheel on the rear side of the vehicle body to the rear floor panel. By fixing the periphery of the wheel on the front and rear sides of the vehicle body to the rear floor panel, a vibration mode in which the vehicle front side and the vehicle rear side of the rear floor panel vibrate in opposite phases in the vehicle vertical direction is excited. The volume change of the vehicle is offset between the vehicle body front side and the vehicle body rear side, and the sound generation amount generated from the rear floor panel can be reduced.

JP 2003-335271 A JP 2009-018744 A

  However, in the spare tire mounting structure described in Patent Documents 1 and 2, the bounce resonance frequency (resonance frequency in the vehicle vertical direction) of the spare tire is close to the resonance frequency of the floor panel that contributes to vehicle interior resonance. Therefore, when the spare tire vibrates due to the bounce resonance, the floor panel is increased in the vertical vibration, which may further increase the noise of the vehicle interior.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a spare tire mounting structure that reduces the vertical vibration of the floor panel and reduces the noise of the vehicle interior. .

  In order to achieve the above object, the invention according to claim 1 is a spare tire mounting structure in which a center portion of a spare tire is fixed to a floor panel of a vehicle by a fixing member, wherein the fixing member includes the spare tire and the floor. A low-rigidity portion having a lower rigidity in the vehicle width direction than a rigidity in the vehicle front-rear direction is provided between the panel and the panel.

  The invention according to claim 2 is the spare tire mounting structure according to claim 1, wherein the fixing member is rotatable in the vehicle width direction around the low-rigidity portion.

  According to this invention, the fixing member has the low rigidity portion between the spare tire and the floor panel, which has a lower rigidity in the vehicle width direction than the rigidity in the vehicle front-rear direction. By configuring the rigidity of the fixing member in the vehicle width direction to be lower than the rigidity of the fixing member in the vehicle front-rear direction, only the roll resonance frequency of the spare tire can be reduced, and the roll resonance frequency can be brought close to the bounce resonance frequency. Roll resonance reduces vibration in the vertical direction of the vehicle due to bounce resonance and suppresses vertical vibration of the floor panel because both ends of the spare tire facing each other centering on the center of the spare tire vibrate in opposite phases in the vertical direction of the vehicle. can do. Therefore, it is possible to suppress the vertical vibration of the floor panel and to reduce the volume noise in the passenger compartment.

It is a mimetic diagram showing an example of a clamp bolt of a spare tire attachment structure concerning this invention. It is a perspective view which shows the rear floor panel of the spare tire mounting structure which concerns on this invention. It is sectional drawing which shows an example of the clamp bolt of the spare-tire mounting structure which concerns on this invention. (A) is a schematic diagram which shows the bounce resonance of the conventional spare tire. (B) is a schematic diagram which shows the roll resonance of the conventional spare tire. (C) is a schematic diagram showing resonance in which roll resonance and bounce resonance of the spare tire according to the present invention are combined.

  Next, the present invention will be described based on specific examples. The spare tire mounting structure of the present invention is a mounting structure configured to suppress the vertical vibration of the floor panel by utilizing the roll resonance of the spare tire in order to reduce the booming noise in the passenger compartment. Further, it may be a front wheel drive vehicle, a rear wheel drive vehicle, a four wheel drive vehicle, or the like that uses an internal combustion engine and a motor as a power source.

  A passenger compartment (not shown) is formed on the front side of the vehicle, and a luggage compartment (not shown) is formed on the rear side of the vehicle in a vehicle compartment inside the vehicle (not shown). In addition, a rectangular rear floor side member (not shown) extending in the vehicle front-rear direction is disposed at both ends in the width direction of the rear portion of the vehicle. Between the rear floor side members in the vehicle width direction, a plate-like rear floor panel 1 is disposed as shown in FIG.

  As shown in FIGS. 2 and 3, the rear floor panel 1 is formed such that a substantially semicircular recess 3 is recessed downward in the vehicle so that the spare tire 2 can be accommodated. The bottom part of the recessed part 3 is formed in flat shape, and the protrusion part 4 which protrudes above a vehicle is formed in the center part. The projecting portion 4 has a nut 4a inside, and is configured such that a fixing member described later is inserted and fitted therein. The rear floor panel only needs to be configured so that a spare tire can be attached, and may have a flat plate shape.

  As shown in FIG. 3, the spare tire 2 is arranged such that the side surface of the circular disk portion 5 attached to a hub (not shown) to which the driving force of the vehicle is transmitted faces the bottom portion 3 of the rear floor panel 1. It is stored in the recess 3 of the rear floor panel 1. A circular hub hole 5 a penetrating the disk portion 5 is provided at the center of the disk portion 5, and the hub hole 5 a is disposed so as to face the protruding portion 4 of the recess 3. The central portion 5 a of the disk portion 5 of the spare tire 2 and the protruding portion 4 of the concave portion 3 of the rear floor panel 1 are fixed by a fixing member 6. In addition, in order to improve the quietness of a rear floor panel, you may arrange | position a damping sheet, a coating type damping material, etc. between a spare tire and a rear floor panel. Further, the spare tire and the rear floor panel may be in contact with each other.

  Specifically, as shown in FIG. 1, the fixing member (clamp bolt) 6 has a head portion 7 that presses the disk portion 5 toward the bottom of the rear floor panel 1, and a state in which the disk portion 5 is pressed by the head portion 7. The shaft portion 8 is fixed to the projecting portion 4 of the rear floor panel 1, and the low-rigidity portion 9 is lower in rigidity in the vehicle width direction than in the vehicle front-rear direction.

  The head portion 7 is formed of a resin member and is formed in a disk shape 7 a having a diameter larger than the inner diameter of the hub hole 5 a of the disk portion 5. Moreover, the center part of the disk shape 7a protrudes in the substantially gear shape 7b in the thickness direction so that it may be easy to rotate the head part 7 centering around the shaft part 8. A washer may be disposed between the head portion and the disk portion.

  Further, the resonance frequency in the roll direction (in other words, the vehicle width direction) of the spare tire 2 arranged and fixed in the recess 3 of the rear floor panel 11 of the vehicle is lowered to reduce the resonance frequency in the bounce direction (in other words, the vehicle vertical direction). In order to approach the resonance frequency, the clamp bolt 6 has a low-rigidity portion 9 between the spare tire 2 and the rear floor panel 11 in the vehicle vertical direction that has a lower rigidity in the vehicle width direction than in the vehicle front-rear direction. Yes. The shaft portion 8 of the clamp bolt 6 is composed of one shaft portion 8 a connected to the head portion 7 and the other shaft portion 8 b fixed to the protruding portion 4 of the rear floor panel 1. Are connected by a low-rigidity portion 9 having lower rigidity in the vehicle width direction than that in the vehicle longitudinal direction. The low-rigidity portion 9 is a connection mechanism that connects one shaft portion 8a and the other shaft portion 8b so as to be rotatable in the width direction of the vehicle. When the concave portion 3 of the rear floor panel 1 and the center portion of the spare tire 2 are fixed by the clamp bolt 6, this connecting mechanism is provided between the disc portion 5 of the spare tire 2 and the concave portion 3 of the floor panel in the vehicle vertical direction. The roll direction of the vehicle and the rotation direction of the clamp bolt 6 are configured to coincide with each other. Further, a mark 10 is provided at the edge of the head portion 7 to indicate the direction of rotation by the coupling mechanism of the clamp bolt 6, that is, the direction in which the clamp bolt 6 is bent. Further, as shown in FIG. 2, the rear floor panel 1 is provided with an arrow 10A indicating the width direction of the vehicle. By aligning the mark 10 with the arrow 10A, the spare tire 2 is swung along with the rolling of the vehicle. The movement is allowed. The low-rigidity portion of the fixing member may be configured to reduce the resonance frequency in the roll direction of the spare tire so as to approach the resonance frequency in the bounce direction.

  Next, the operation of the spare tire mounting structure according to the present invention will be described with reference to FIG. When the rear floor panel 1 to which vibration caused by repeated fluctuation of torque output from the internal combustion engine, vibration input from the road surface, or the like is vibrated, the vibration transmitted to the rear floor panel 1 is fixed to the rear floor panel 1. Is transmitted to the spare tire 2. In addition, the code | symbol A of FIG. 4 represents the position of the stationary state where the spare tire is not vibrating.

  As shown in FIG. 4A, when vibration in the bounce direction (vehicle up-down direction) of the spare tire 2 is generated in the conventional clamp bolt spare tire mounting structure, that is, the bounce resonance is caused by the hub hole 5a of the spare tire 2. The two ends 2a and 2b of the spare tire 2 that face each other about the shaft vibrate in the same phase in the vehicle vertical direction around the shaft portion 8 of the clamp bolt 6.

  Further, as shown in FIG. 4 (b), when vibration in the roll direction (vehicle width direction) of the spare tire 2 occurs in the conventional spare bolt mounting structure of the clamp bolt, that is, roll resonance occurs in the hub of the spare tire 2. Both end portions 2a and 2b of the spare tire 2 facing each other with the hole 5a as the center vibrate in the opposite phase in the vehicle vertical direction around the shaft portion 8 of the clamp bolt 6.

  As shown in FIG. 4 (c), the spare tire mounting structure according to the present invention has a low rigidity portion 9 of the shaft portion 8 of the clamp bolt 6 in which the rigidity in the vehicle width direction is set lower than the vehicle front-rear direction. Since the roll resonance frequency and the bounce resonance frequency of the spare tire 2 to which vibration is transmitted are close to each other, the vibration in the roll direction of the spare tire 2 and the vibration in the bounce direction of the spare tire 2 are caused by the vibration transmitted from the rear floor panel 1. Will occur. Therefore, the anti-phase vibration generated by the roll resonance can reduce the vertical vibration of the vehicle due to the bounce resonance of the spare tire 2, and as a result, the vertical vibration of the rear floor panel 1 connected to the spare tire 2 is suppressed. can do. Therefore, it is possible to suppress the vertical vibration of the floor panel and to reduce the volume noise in the passenger compartment.

  The spare tire mounting structure according to the present invention reduces the vertical vibration of the floor panel by reducing the vibration in the vehicle vertical direction due to the bounce resonance by utilizing the roll resonance of the spare tire in order to reduce the booming noise in the passenger compartment. Any structure may be used as long as it is configured to suppress, and is not limited to the above-described structure.

  DESCRIPTION OF SYMBOLS 1 ... Floor panel, 2 ... Spare tire, 2a, 2b ... Both ends (spare tire), 5 ... Disc part, 5a ... Center part (disc part), 6 ... Fixing member (clamp bolt), 9 ... Low rigidity Part (coupling mechanism).

Claims (2)

In the spare tire mounting structure in which the center of the spare tire is fixed to the floor panel of the vehicle by a fixing member,
The spare tire mounting structure, wherein the fixing member includes a low rigidity portion having a rigidity in a vehicle width direction lower than a rigidity in a vehicle front-rear direction between the spare tire and the floor panel.   The spare tire mounting structure according to claim 1, wherein the fixing member is rotatable in the vehicle width direction around the low-rigidity portion.

Images