JPH031484B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vehicle body support structure for an electric radiator fan that supports the electric radiator fan on the vehicle body in a vehicle having a radiator elastically supported on the vehicle body. Generally, the radiator is elastically supported by the vehicle body via multiple anti-vibration rubbers, and the radiator is supported by the damper mass.
It is known that a dynamic damper using anti-vibration rubber as a damper member is operated to suppress vibrations of a vehicle body as much as possible. A first conventional example of a vehicle body support structure for an electric radiator fan in a vehicle having a structure in which such a radiator is operated as a dynamic damper is as shown in Utility Model Application Publication No. 55-113842 or as shown in Figs. 1 and 2. There is something. In the figure, reference numeral 1 denotes a radiator installed in a vehicle M. A pair of support brackets 2, 2 are provided at the upper part of the radiator, and a pair of male threads 3, 2 are provided at the lower part of the radiator.
3 is provided in a hanging state. Each support bracket 2 provided on the upper part of the radiator 1 is attached to a radiator core support 5, which is a part of the vehicle body, via an atsupa mount insulator 4 made of anti-vibration rubber, which is a damper member. Each male screw 3 provided at the lower part of the vehicle body 1 is attached to a first cross member 7, which is a part of the vehicle body, via a lower mount insulator 6, which is a damper member. Reference numeral 8 denotes a fan shroud of the electric radiator fan, which is formed from a flat plate portion 8a having approximately the same size as the radiator 1 and a cylindrical fan cover portion 8b. An electric fan 10 is provided with four stays 9 extending radially at approximately equal angular intervals on the outer periphery of the fan cover portion 8b and having blades 10a.
is fixed. The tip of each stay 9 provided on the fan cover portion 8b of the fan shroud 8 is a part of the vehicle body (not shown), and the flat plate portion 8a is a seal member 1 formed of urethane to ensure airtightness.
1 and is fixed so as to be pressed against the back surface of the radiator 1. As described above, since the radiator 1 is attached to the vehicle body via the upper mount insulator 4 and the lower mount insulator 6, which are damper members, the radiator 1 is prevented from being damaged when the vehicle runs on an uneven road, for example. Even if an excitation force is applied to the vehicle body, the radiator 1 and these insulators 4 and 6 exert a dynamic damper effect and try to suppress the vibrations of the vehicle body. However, since the back surface of the radiator 1 is pressed against the flat surface 8a of the fan shroud 8 via a seal member 11 to ensure airtightness, the vertical movement of the radiator 1 is restricted by the seal member 11, and the radiator 1 There was a problem in that the effect of a dynamic damper in which the upper mount insulator 4 and the lower mount insulator 6 arranged above and below are damper members and the radiator 1 is the damper mass is not sufficiently exhibited. Therefore, the vehicle body support structure of the second conventional electric radiator fan that takes such problems into consideration is as follows:
For example, there is one shown in FIG. In the drawings, parts or members that are the same or equivalent to those in the prior art example described above are designated by the same reference numerals and redundant explanations will be omitted. In this embodiment, the flat plate portion 18a of the fan shroud 18 is directly fixed to the radiator 1.
In addition, the fan cover portion 1 of the fan shroud 18
An electric fan 20 having blades 20a is fixed to 8b. The attachment of the radiator 1 to the radiator core support 5 and the first cross member 7 is the same as in the conventional example described above. In this conventional example, an electric fan 20 is installed in the radiator 1.
Since the fan shroud 18 to which is fixed is directly fixed, the fan shroud 18 does not restrict the vertical movement of the radiator 1 as described above, and the upper mount insulator 4 and the lower mount insulator 6 are used as damper members. , the effect of a dynamic damper using the radiator 1 as the damper mass can be fully exhibited, and the problems of the first conventional example have been solved. However, the electric fan 20 is installed in the radiator 1.
Since the fan shroud 18 to which is fixed is directly fixed, when the electric fan 20 is of the rotation speed switching type, vibrations generated in the electric fan 20 due to fan imbalance are transmitted to the radiator 1, causing the radiator 1 to Since the radiator 1 is vibrated, there is a problem in that the vibration sound of the radiator 1 brings noise into the vehicle interior. Furthermore, this conventional example also has the following problems. Let us now consider this conventional example by modeling it into a vibration model of a one-degree-of-freedom system as shown in FIG.
In the figure, A is the vehicle body, B is the integrated radiator 1, fan shroud 18, and electric fan 20, and K and C are the vehicle body A and the radiator 1, respectively.
These are the spring constants and viscous damping coefficients of the upper mount insulator 4 and the lower mount insulator 6, which are made of anti-vibration rubber and are damper members provided between the . By the way, the electric fan 20 generally generates unbalanced excitation force through rotation.
This unbalanced excitation force causes the vehicle body A to vibrate via the damper member. Therefore, when the unbalanced excitation force is Po sin wt and the transmission force transmitted to the vehicle body A is Pt sin (wt + φ), the relationship between the frequency w of the unbalanced excitation force and the vibration transmission rate Pt/Po is This is shown by the vibration transmissibility curve X in the graph of FIG. The vertical axis shows the vibration transmissibility Pt/Po, and the horizontal axis shows the frequency w of the unbalanced excitation force. Here, the frequency wo of the unbalanced excitation force when the vibration transmissibility Pt/Po is OdB is the natural frequency of the vibration system consisting of the radiator 1, etc. and the damper member.

Equal to √2 times [formula]. By the way, in order to prevent the car body from resonating, the natural frequency wn of the vibration system consisting of the radiator 1 etc. and the damper member is usually set to the bending natural frequency of the car body, that is, about 2π×23 [rad/sec]. It is set to a value of , to bring out the dynamic damper effect. Therefore, when the vibration transmissibility Pt/Po is OdB, the frequency wo of the unbalanced excitation force is set near wo=√2×2π×23 [rad/sec]. Under such conditions, if the rotational speed of the electric fan 20 is below Rev=wo/2π×60=√2×23×60=1950 (rpm), the vibration transmissibility curve X in the graph of FIG. As shown, the vibration transmissibility Pt/Po is on the plus side in dB. Therefore,
The vehicle body A receives a transmitted force larger than the unbalanced excitation force generated from the electric fan 20 and vibrates. In recent years, in situations where electric fans of the rotational speed switching type are frequently used, the fans are often used at rotational speeds within this range, so a structure like this conventional example is not preferred. This invention was made in view of these conventional problems, and involves fixing a fan shroud to a radiator through a sealing member, and attaching an electric fan to the vehicle body so as to be elastically supported through a damper member. The aim is to solve the above problems by doing so. The present invention will be explained below based on the drawings. FIGS. 6 to 8 are diagrams showing an embodiment of the present invention. In the figures, the same or equivalent parts or members as in the conventional example are given the same reference numerals and redundant explanations will be omitted. A pair of mounting flanges 29, 29 are provided on both sides of the flat plate portion 28a of the fan shroud 28, respectively, and a seal member 11 made of urethane is attached around the radiator side surface of the flat plate portion 28a. These mounting flanges 29 provided on the flat plate portion 28a are each fastened to both sides of the radiator 1 with bolts 30, and are attached to the back surface of the radiator 1 via the seal member 11 to the fan shroud 2.
8 flat plate portions 28a are fixed. At this time,
Airtightness is maintained between the radiator 1 and the fan shroud 28 by compressing the seal member 11. Further, the fan shroud 28 has a fan cover portion 28b. On the other hand, electric fan 31 of electric radiator fan
Four stays 32 are provided radially extending at approximately equal angular intervals on the outer periphery of the
2 is fixed to a part of the vehicle body (not shown) so as to be elastically supported via an insulator 33 which is a damper member and is made of anti-vibration rubber. At this time, the blades 31a of the electric fan 31 are disposed within the fan cover portion 28b of the fan shroud 28. Next, the effect will be explained. When the car body vibrates and an excitation force is applied to the car body,
Since the fan shroud 28 is directly fixed to the radiator 1, the fan shroud 28 no longer restricts the vertical movement of the radiator 1 as in the first conventional example, and the upper mount insulator 4 and lower mount insulator 6 It is possible to exhibit the effect of a dynamic damper in which the radiator 1 is a damper member and the radiator 1 is a damper mass. Further, since the fan shroud 28 is fixed to the radiator 1 via the seal member 11, airtightness is maintained between the radiator 1 and the fan shroud 28 by the seal member 11, and the radiator 1 is cooled by the electric fan 31. Efficiency has been improved. Furthermore, since the fan shroud 28 is directly fixed to the radiator 1, the mass of the auxiliary vibration system constituted by the radiator 1 becomes large, and the effect of the dynamic damper is also increased. The reason for this will be explained below. FIG. 7 is a diagram showing an embodiment of the present invention modeled as a two-degree-of-freedom vibration model in relation to the vehicle body. In the figure, A' is the vehicle body, B' is the radiator 1 and the fan shroud 28, and it is assumed that the excitation force Fo sin wt is acting on the vehicle body A'. In addition, m is the radiator 1 and the fan shroud 28
, M is the mass of the vehicle body, K is the spring constant of the spring member between the vehicle body A' and the tire contact surface,
k and c are the spring constants and viscous damping coefficients of the upper mount insulator 4 and lower mount insulator 6, which are made of anti-vibration rubber and are damper members provided between the vehicle body A' and the radiator 1, respectively. It is. A main vibration system is constituted by the vehicle body A' and a spring member having a spring constant K, and a sub-vibration system is constituted by the radiator 1, the fan shroud 28, and a damper member having a spring constant k and a viscous damping coefficient c. FIG. 8 is an amplitude magnification curve Y of the dynamic damper according to FIG. 7, where the vertical axis shows the amplitude magnification |
| (X is the amplitude of the vehicle body, Xst is the amount of static deflection Fo/K), and the horizontal axis is the ratio of the frequency of the excitation force to the natural frequency of the width vibration system w/wn (w is the excitation force The frequency of force, wn, is the natural frequency of the secondary vibration system,

It is represented by [Formula]. ) is taken. It is desirable that the amplitude X of the vehicle body A' becomes uniformly small over the entire range of the frequency w of the excitation force. The values of amplitude magnification |X/Xst| at points P and Q are set to be approximately equal. That is, the ratio of natural frequencies wn/Ωn (where wn is as described above, Ωn is the natural frequency of the main vibration system,

It is represented by [Formula]. ) and the viscous damping ratio φ≡C/Cc (Cc is the critical damping coefficient, expressed as Cc=2√) are set so as to satisfy the following equation. wn/Ωn=1/(1+μ) φ=√38(1+) ³ (1) Here, μ is called mass ratio and is defined as μ≡m/M. At this time, the amplitude magnification |X/Xst| at the two points P and Q is expressed by the following equation. This shows that as the mass ratio μ increases, the amplitude magnification |X/Xst| decreases. In the case of the embodiment of the present invention, the mass of the sub-vibration system is the radiator 1 and the fan shroud 28 integrated, so the mass m of the sub-vibration system is greater than when the mass of the sub-vibration system is only the radiator. becomes larger, and therefore the mass ratio μ also becomes larger. Therefore, it is clear from equation (2) that the amplitude magnification |X/Xst| at the two points P and Q becomes smaller, and the dynamic damper effect becomes larger. Furthermore, in this embodiment, since the electric fan 31 is fixed to the vehicle body via the insulator 33 so as to be elastically supported, the electric fan 31 is separate from the fan shroud 28, and the electric fan 31 is separated from the fan shroud 28.
The unbalanced excitation force generated when the fan shroud 28 rotates is transmitted to the radiator 1 to which the fan shroud 28 is fixed.
The radiator 1 is not vibrated by the unbalanced excitation force. In addition, an insulator 33, which is a damper member, is interposed between the electric fan 31 and the vehicle body so that the electric fan 31 is elastically supported by the vehicle body, so that an imbalance occurs when the electric fan 31 rotates. The excitation force is less likely to be transmitted to the vehicle body, and vibrations of the vehicle body are suppressed as much as possible. The reason will be explained below. FIG. 9 is a diagram showing a vibration system consisting of an electric fan 31 and an insulator 33 in an embodiment of the present invention modeled as a vibration model of a one-degree-of-freedom system. Here, A'' is the vehicle body, C is the electric fan 31 (vibrating body), m' is the mass of the electric fan 31, and K' and C' are the dampers provided between the vehicle body A'' and the electric fan 31, respectively. These are the spring constant and viscous damping coefficient of the insulator 33, which is a member. In addition, the unbalanced excitation force is Po sin wt, and the excitation force transmitted to the vehicle body A'' is Pt sin (wt+φ). At this time, the frequency w of the unbalanced excitation force of the electric fan 31 and the vibration transmission The relationship between the vibration transmission rate Pt/Po is shown by the vibration transmissibility curve Y' in the graph of Figure 10. Here, w ₁ ' is the frequency at which the vibration transmission rate Pt/Po is OdB, and this vibration As mentioned in the explanation of the conventional example, the number is the natural frequency of the vibration system consisting of the electric fan 31 and the insulator 33.

It is twice the [formula]. That is,

It is written as [Formula]. Currently, the minimum rotation speed for electric fans is Rev.
rpm, then W ₁ ′/2π×60<Rev i.e.

By selecting the mass m' of the electric fan 31 and the spring constant k' of the insulator 33 so that Since the excitation force (amplitude amount) is smaller than Po, the vibration of the vehicle body A'' caused by the electric fan 31 is suppressed as much as possible. As explained above, according to this invention,
A vehicle body support structure for an electric radiator fan, wherein the vehicle has a radiator elastically supported by a vehicle body via a plurality of damper members, and the vehicle body supports an electric radiator fan consisting of a fan shroud and an electric fan. In,
The fan shroud is fixed to the radiator via a seal member, and the electric fan is attached to the vehicle body so as to be elastically supported via a damper member. The cooling efficiency of the radiator by the electric fan has been improved, and the dynamic damper effect, which is composed of a radiator and a damper member as in the past, is not impaired, and since the fan shroud is fixed to the radiator, it is possible to improve the cooling efficiency of the radiator. The mass of the auxiliary vibration system is increased, and the dynamic damper effect is increased. In addition, the electric fan is separate from the fan shroud and is fixed to the vehicle body via a damper member, so the unbalanced excitation force of the electric fan will not cause the radiator to vibrate and cause noise in the vehicle interior. Furthermore, the unbalanced excitation force is less likely to be transmitted to the vehicle body, resulting in the effect that vibration of the vehicle body is suppressed as much as possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing a vehicle having a vehicle body support structure for an electric radiator fan of a first conventional example;
Fig. 2 is a perspective view showing the vehicle body support structure of the electric radiator fan, Fig. 3 is an exploded perspective view showing the car body support structure of the electric radiator fan of the second conventional example, and Fig. 4 is a perspective view of the car body support structure of the electric radiator fan of the second conventional example. 5 is a graph showing the vibration transmission rate of the vibration model of FIG. 4, and FIGS. 6 to 10 are vehicle body support structures for electric radiator fans according to the present invention. One embodiment is shown, and Fig. 6 is an exploded perspective view showing the vehicle body support structure of the electric radiator fan, and Fig. 7 is an explanation of the vibration model when this embodiment is considered as a two-degree-of-freedom system in relation to the vehicle body. Figure 8 is a graph showing the amplitude magnification of the vibration model in Figure 7, Figure 9 is an explanatory diagram of the vibration model when considering the electric fan as a one-degree-of-freedom system, and Figure 10 is the vibration in Figure 9. It is a graph showing the vibration transmissibility of the model. 1...Radiator, 4...Atsupa mount insulator (damper member), 5...Radiator core support (vehicle body), 6...Lower mount insulator (vehicle body), 7...First cross member (vehicle body) ), 28...Juan Shuroud, 31...
...Electric fan, 33...Insulator (damper member).

Claims (1)

[Scope of Claims] 1. An electric radiator fan comprising a radiator elastically supported on a vehicle body via a plurality of damper members, the vehicle body supporting an electric radiator fan consisting of a fan shroud and an electric fan. A vehicle body support structure for an electric radiator fan, characterized in that a fan shroud is fixed to the radiator via a seal member, and an electric fan is attached to the vehicle body so as to be elastically supported via a damper member.