JP2008149888A - Support structure for power plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support structure for a power plant capable of preventing failure of an engine support caused by torsion deformation and bending deformation of right and left side frames during turning of a vehicle and of sufficiently improving frame rigidity. <P>SOLUTION: The pair of side frames 1a are extended to the vehicle body longitudinal direction leaving a gap in the vehicle width direction and are mounted with mount brackets 6. The both mount brackets 6 are connected with each other by support cross members 7. The support cross member 7 is formed of a flat plate to have an approximately rectangular cross section with long sides in the vertical direction. The support cross members 7 are made resist to vertical bending loads input from the side frames 1a so as to improve the rigidity of the frames 1a. With respect to forward/backward bending loads and torsion caused by deformation of the side frames 1a during turning, failure is prevented by bending the support cross members 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power plant support structure, and more particularly to a power plant support structure for supporting a power plant such as an engine or transmission between a pair of left and right side frames extending in the front-rear direction.

  For example, in large vehicles such as trucks and buses, a pair of side frames extending in the longitudinal direction of the vehicle body are arranged at predetermined intervals in the vehicle width direction, and these side frames are connected to each other by a plurality of cross members. To form a ladder-type frame. The engine and the transmission are disposed between the side frames at the front of the vehicle body, and are supported by an engine mount and a mission mount, respectively. Since the power plant of a large vehicle has a considerable weight, the part where the power plant of the left and right side frames is mounted is easily deformed into a cross-sectional shape so as to expand downward under the load. In order to prevent frame deformation, a reinforcing measure is taken to connect the left and right side frames to each other by a cross member disposed below the power plant (see, for example, Patent Document 1).

The technique of the above-mentioned Patent Document 1 relates to a support structure of an engine. An engine support that is bent downward by press molding is manufactured and disposed on the lower side of the engine, and the left and right side frames are mounted by the engine support. A pair of engine mounts are fixed on the engine support to support the engine.
Utility Model No. 2513616 Specification

  By the way, the frame rigidity has a great influence on the quietness of the cabin and the running characteristics of the vehicle.For example, when the frame rigidity is lowered, the engine vibration during idle operation is easily transmitted to the cabin, which is a factor that impairs the quietness of the cabin. Become. As described above, the engine support of Patent Document 1 prevents the side frame from expanding downward and contributes to the improvement of the frame rigidity. However, the steel plate engine support itself has a low rigidity, The resulting improvement in frame rigidity was not sufficient.

  Therefore, measures to improve the rigidity of the engine support by increasing the plate thickness or changing the material can be considered, but the engine support that connects the left and right side frames is twisted and deformed on the left and right side frames as the vehicle turns. Therefore, if the engine support is difficult to be deformed due to the improvement in rigidity, the stress of the engine support is inevitably increased and may be damaged. Therefore, in the conventional power plant support structure, the rigidity of the engine support has to be limited to prevent breakage, and as a result, good frame rigidity cannot be achieved.

  The present invention has been made to solve such problems, and the object of the present invention is to prevent engine support from being damaged due to torsional deformation and bending deformation of the left and right side frames during vehicle turning. Another object of the present invention is to provide a power plant support structure that can sufficiently improve the frame rigidity.

  In order to achieve the above object, the invention according to claim 1 is a power plant support structure for supporting a power plant between a pair of left and right side frames extending in the front-rear direction at intervals in the vehicle width direction. A mounting bracket that is attached to each side frame and supports the power plant via an elastic member, and left and right ends are connected to the left and right mounting brackets, respectively, and the cross-sectional shape along the longitudinal direction of the vehicle body is the long side in the vertical direction And a support cross member made of a substantially rectangular flat plate.

  Therefore, the mounting brackets are fixed to the left and right side frames, and both mounting brackets are connected to each other by the support cross members. The cross-sectional shape of the support cross member along the longitudinal direction of the vehicle body is substantially rectangular with the long side in the vertical direction, so the secondary moment for the bending load in the vertical direction is large, and the cross-section for the bending load in the longitudinal direction is large. The second moment is small.

  The support cross member is designed to expand to the lower side of the left and right side frames due to the load of the power plant while resisting bending loads in the vertical direction as well as compression and tensile loads in the vehicle width direction input from the left and right side frames. It prevents opening and contributes to improved frame rigidity. The bending load in the vertical direction acts on the support cross member in the so-called in-plane direction (the direction in which deformation is most difficult), and the support cross member opposes with a large moment of inertia in the cross section. And improved frame rigidity.

  On the other hand, when torsional deformation or bending deformation occurs in the side frame as the vehicle turns, the support cross member may bend in the front-rear direction under a bending load in the front-rear direction or twist between the left and right mounting brackets. This prevents the occurrence of high stress and prevents breakage. The bending load in the front-rear direction acts on the support cross member in a so-called out-of-plane direction (the direction in which deformation is most likely), and the support cross member is easily bent with a small secondary moment of inertia. Since the twist is easily generated, in any case, the generation of stress is suppressed and the breakage is prevented.

According to a second aspect of the present invention, in the first aspect, the left and right mounting brackets hang down integrally from the bottom surface of the mounting bracket and form a substantially T shape with respect to the bottom surface as viewed from the side of the vehicle body. A cross member mounting portion is provided, and both left and right ends of the support cross member are overlapped and connected to the cross member mounting portion from the vehicle body front side or the vehicle body rear side.
Accordingly, since the input when the side frame is deformed is transmitted to the support cross member via the cross member mounting portion of the mount bracket, it is necessary to prevent the cross member mounting portion from being damaged due to the generation of stress during input transmission. The cross member mounting part that hangs downward from the bottom surface of the mounting bracket has a shape that is relatively easy to bend and twist in the front-rear direction. Is prevented in advance. Further, the manufacturing cost can be reduced by integrating the cross member mounting portion with the mounting bracket.

According to a third aspect of the present invention, in the first or second aspect, the support cross member has an arc shape with the middle portion protruding downward with both left and right ends connected to the mount bracket. It is possible to lower the engine mounting position while avoiding the interference.
According to a fourth aspect of the present invention, in the first to third aspects, the support cross member has chamfered portions formed at four corners having a substantially rectangular cross section.

  Therefore, stress generation of the support cross member is further suppressed by the chamfered portions formed at the four corners having a substantially rectangular cross section.

As described above, according to the power plant support structure of the first aspect of the present invention, it is possible to prevent damage to the support cross member due to torsional deformation or bending deformation of the left and right side frames when the vehicle is turning. The frame rigidity can be sufficiently improved.
According to the power plant support structure of the invention of claim 2, in addition to claim 1, it is possible to prevent damage by suppressing the generation of stress in the cross member mounting portion, and to integrate the mounting bracket and the cross member mounting portion. As a result, the manufacturing cost can be reduced.

According to the power plant support structure of the third aspect of the invention, in addition to the first and second aspects, the center of gravity of the vehicle can be lowered by lowering the mounting position of the engine, and its running stability can be improved. .
According to the power plant support structure of the fourth aspect of the present invention, in addition to the first to third aspects, it is possible to further improve the rigidity by suppressing the stress generation of the support cross member.

Hereinafter, an embodiment in which the present invention is embodied in an engine support structure will be described.
FIG. 1 is a plan view showing a vehicle frame to which the engine support structure of the present embodiment is applied, and FIG. 2 is a perspective view showing a mounting bracket and a support cross member for supporting the rear part of the engine. In this embodiment, the invention is embodied in a support structure for an engine mounted on a truck. However, the present invention is not limited to this as long as the vehicle includes a ladder-type frame having a pair of side frames. Good.

  A pair of side frames 1a of the vehicle extend in the longitudinal direction of the vehicle body at a predetermined interval in the vehicle width direction, and these side frames 1a are connected to each other by a plurality of cross members 1b to constitute a ladder-type vehicle body frame 1. is doing. As shown in FIG. 1, an engine 2 and a transmission 3 which are vehicle power plants are mounted on the front portion of the vehicle body frame 1, and although not shown, the vehicle body frame 1 has functions such as a suspension device for supporting wheels. Parts are mounted, and a cabin, a loading platform and the like are mounted on the body frame 1.

  Hereinafter, the support structure of the engine 2 will be described. The engine 2 is supported by a total of four points including two front portions and two rear portions. Brackets 2a are attached to the front left and right sides of the engine 2, and these brackets 2a are respectively attached to the left and right side frames 1a via engine mounts 4 equipped with anti-vibration rubber. The mount 4 supports the left and right side frames 1a.

  On the other hand, the support structure of the rear part of the engine 2 includes a mount bracket 6 fixed to each of the left and right side frames 1a, and a support cross member 7 that couples the mount brackets 6 to each other. FIG. 3 is a partially enlarged perspective view of FIG. 2 showing a configuration around the mounting bracket 6 on the right side of the vehicle body, and FIG. 4 is a front view of the mounting bracket 6. Hereinafter, the configuration of the mounting bracket 6 on the right side of the vehicle body will be described with reference to these drawings, but the left mounting bracket 6 has the same configuration that is symmetrical.

  The mount bracket 6 is disposed at the front and rear positions corresponding to the rear part of the engine, and the main body bracket 8 and the floating block 9 constituting the mount bracket 6 are each cast as a casting. The base portion 10 of the main body bracket 8 has a square plate shape along the inner surface of the side frame 1a, and the inner surface of the side frame 1a (the inner side in the vehicle width direction) through bolt holes 10a penetrating through the four corners. 3 is fixed to the right side of FIG. 3 and the front side of FIG. 4 by a bolt 11 (indicated by a bolt axis in FIG. 3). An elastic support chamber 12 is integrally formed on the inner side of the base portion 10, and the elastic support chamber 12 is opened upward and inward, and a pair of inclined surfaces 12a facing the upper diagonally rear and the upper diagonally front are formed therein. Is formed.

  A floating block 9 is disposed in the elastic support chamber 12. The floating block 9 is exposed upward and inward from the elastic support chamber 12, and the surface exposed upward is used as a support surface 9b. The floating block 9 is formed with a pair of inclined surfaces 9a facing diagonally downward and obliquely downward and forward, and these inclined surfaces 9a are spaced apart from the inclined surface 12a of the elastic support chamber 12 at a predetermined interval. They are connected by vibration-proof rubber 13 (elastic member). The anti-vibration rubber 13 is bonded to the inclined surfaces 9a and 12a during vulcanization molding, whereby the floating block 9 is supported at a predetermined position in the elastic support chamber 12. In this state, the floating block 9 is separated from all the inner walls of the elastic support chamber 12, and can be displaced by the bending of the vibration-proof rubber 13.

  A bracket 2b provided at the rear portion of the engine 2 is disposed on the support surface 9b of the floating block 9, and the bracket 2b uses a female screw 9c formed on the support surface 9b of the floating block 9 to form a pair of bolts 15b. (Indicated by a bolt axis in FIG. 3) is fixed to the support surface 9b. The left mounting bracket 6 is configured in the same manner, whereby the rear portion of the engine is supported between the left and right side frames 1a via the mounting bracket 6.

The mount bracket 6 is configured as described above, and vibration generated from the engine 2 is absorbed by the vibration isolating rubber 13 of the front engine mount 4 and the rear mount bracket 6 when the engine 2 is in operation.
On the other hand, a cross member mounting portion 17 is integrally formed at the lower portion of the elastic support chamber 12 of the main body bracket 8. The cross member mounting portion 17 is suspended downward from the center in the front-rear direction of the bottom surface 12b of the elastic support chamber 12 and has a plate shape having a predetermined thickness in the front-rear direction of the vehicle body. It is arrange | positioned so that a substantially T shape may be made | formed by side view. A rib 18 is integrally formed on the outer side of the cross member mounting portion 17 from the bottom surface 12b of the elastic support chamber 12 to an intermediate position of the cross member mounting portion 17, and the rib 18 has a predetermined thickness in the inside and outside of the vehicle body. It has a plate shape and is arranged so as to have a substantially T-shaped cross section in a plan view with respect to the cross member mounting portion 17.

  The left mounting bracket 6 is configured in the same manner with respect to the cross member mounting portion 17, and the pair of support cross members 7 are disposed between the cross member mounting portions 17 of the left and right mounting brackets 6. Yes. These support cross members 7 are manufactured by punching a steel plate of about 10 mm by press molding, to connect the left and right cross member mounting portions 17 to each other, and to avoid interference with the engine 2 between the left and right side frames 1a. The middle part (the center in the left-right direction of the vehicle body) has a shape projecting in an arc shape downward. By punching the steel plate, the cross-sectional shape of the support cross member 7 along the longitudinal direction of the vehicle body is a substantially rectangular shape with the vertical direction as the long side and the longitudinal direction as the short side, as shown in the cross-sectional view of FIG. Chamfered portions 19 are formed at the four corners of the cross section by chamfering. In the present embodiment, the cross-sectional shapes of the support cross members are all set to be the same in the vehicle width direction.

  The left and right ends of both support cross members 7 sandwich a cross member mounting portion 17 of the mounting bracket 6 from the front side and the rear side, and a pair of bolt holes 7a penetrating the left and right ends, and corresponding bolts of the cross member mounting portions 17 The left and right ends of both support cross members 7 are fixed to the cross member mounting portion 17 by bolts 20 and nuts 21 (indicated by bolt axes in FIG. 3) through holes (not shown).

Next, the operation of the engine support structure constituted by the mount bracket 6 and the support cross member 7 will be described.
First, in the support structure of the engine 2 of the present embodiment, the mount bracket 6 is directly attached to the left and right side frames 1a, so that the engine load hardly acts on the support cross member 7 and is interposed via the mount bracket 6. The engine load is directly supported by the side frame 1a. On the other hand, the left and right side frames 1a are connected to each other by the support cross member 7 through the mount bracket 6 regardless of the support of the engine 2. Has been.

  By the way, as described in [Problems to be Solved by the Invention], from the viewpoint of preventing the side frame 1a from expanding and deforming downward due to the engine weight or the like and improving the rigidity of the frame 1, the support cross member 7 Although improvement in rigidity is required, from the viewpoint of preventing damage to the support cross member 7 due to deformation of the side frame 1a when the vehicle turns, there is a restriction that improvement in rigidity of the support cross member 7 is restricted in order to release input. .

  Here, since the cross-sectional shape of each support cross member 7 is a substantially rectangular shape having a long side in the vertical direction, the cross-section of each support cross member 7 with respect to the vertical bending load indicated by arrow A in FIG. The secondary moment becomes large, and the sectional secondary moment with respect to the bending load in the front-rear direction indicated by the arrow B in FIG. It should be noted that since the two support cross members 7 separated by a predetermined interval are opposed to the bending load in the front-rear direction, the substantial moment of inertia of the cross section differs depending on the interval. Since the cross member 7 is very close (the thickness of the cross member mounting portion 17), the value is much smaller than the cross-sectional second moment with respect to the bending load in the vertical direction.

  The support cross member 7 expands the side frame 1a while resisting the vertical bending load indicated by the arrow A together with the compression / tensile load in the vehicle width direction mainly inputted from the left and right side frames 1a. This contributes to prevention and improved frame rigidity. The bending load in the vertical direction acts on the support cross member 7 in a so-called in-plane direction (the direction in which deformation is most difficult), and the support cross member 7 counters the bending load in the vertical direction with a large second moment of section. Therefore, it is possible to achieve sufficient prevention of the side frame 1a from expanding and improvement in frame rigidity.

  On the other hand, when torsional deformation or bending deformation occurs in the side frame 1a as the vehicle turns, the support cross member 7 is bent in the front-rear direction by receiving a bending load in the front-rear direction indicated by the arrow B, or mounted on the left and right mounts. It is twisted between the brackets 6, thereby preventing the occurrence of high stress and preventing breakage. The bending load in the front-rear direction acts on the support cross member 7 in a so-called out-of-plane direction (the direction in which deformation is most likely to occur), and the secondary moment of the cross-section of the support cross member 7 with respect to the bending load in the front-rear direction is sufficiently small. In addition, since the plate-like support cross member 7 is easily twisted, in any case, it is possible to suppress the occurrence of stress and prevent damage. In addition, the formation of chamfered portions 19 at the four corners of the cross section of the support cross member 7 also contributes to the suppression of stress generation.

  Further, since the input when the side frame 1a is deformed is transmitted to the support cross member 7 via the cross member mounting portion 17 of the mount bracket 6, the cross member mounting portion 17 is also prevented from being damaged due to the generation of stress during input transmission. There is a need to. Here, as described above, the cross member mounting portion 17 has a plate shape that hangs downward from the bottom surface 12 b of the elastic support chamber 12, and has a shape that is relatively likely to bend and twist in the front-rear direction. Therefore, when the side frame 1a is deformed, not only the support cross member 7 but also the cross member mounting portion 17 is restrained from generating stress, and can be prevented from being damaged. Further, since the cross member attaching portion 17 is not formed separately from the mount bracket 6 and is integrally formed by casting, an advantage that the manufacturing cost can be reduced is also obtained.

Furthermore, since the support cross member 7 has a shape projecting downward in an arc shape, the mounting position of the engine 2 can be lowered while avoiding interference with the support cross member 7. Thus, the running stability can be improved by lowering the position of the center of gravity of the vehicle.
On the other hand, in order to avoid interference with the engine 2, the arc-shaped support cross member 7 as described above is suitable, and the arc-shaped support cross member 7 has sufficient rigidity. It is advantageous. For example, in the case where the support cross member 7 having the same rigidity as that of the present embodiment is manufactured from a channel or H-shaped steel, it takes a great deal of time to bend the arc into an arc shape, but the support cross member 7 of the present embodiment is press-molded. Therefore, there is no manufacturing restriction regarding the shape, and there is also a manufacturing advantage that even the arc-shaped support cross member 7 can be manufactured very easily.

  This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the embodiment described above, the support structure for supporting the rear portion of the engine 2 is embodied. However, the front portion of the engine 2 may be supported by a similar support structure. Further, the structure is not limited to this as long as it is a power plant support structure mounted between the left and right side frames 1a, and may be applied to a transmission support structure, for example.

  In the above embodiment, the left and right mounting brackets 6 are connected by the pair of support cross members 7. However, the number and cross-sectional shape (vertical / horizontal ratio) of the support cross members 7 are required according to the configuration of the side frame 1a and the like. The support cross member 7 can be arbitrarily changed according to the rigidity of the support cross member 7. For example, the number of the support cross members 7 may be changed to one or three, or the cross-sectional shape may be changed. Further, the cross-sectional shape of the support cross member 7 does not have to be set all the same in the vehicle width direction. For example, the vertical dimension may be reduced toward the middle compared to the left and right ends of the support cross member 7.

It is a top view which shows the flame | frame of the vehicle to which the support structure of the engine of embodiment was applied. It is a perspective view which shows the mount bracket and support cross member which support an engine rear part. FIG. 3 is a partially enlarged perspective view of FIG. 2 showing a configuration around a mounting bracket on the right side of the vehicle body. It is a front view which similarly shows a mounting bracket. It is the VV sectional view taken on the line of FIG. 2 which shows the cross-sectional shape of a support cross member.

Explanation of symbols

1a Side frame 2 Engine (power plant)
6 Mounting bracket 7 Support cross member 17 Cross member mounting part 19 Chamfered part

Claims (4)

In the power plant support structure for supporting the power plant between a pair of left and right side frames extending in the front-rear direction with an interval in the vehicle width direction,
A mounting bracket attached to each of the left and right side frames and supporting the power plant via an elastic member,
The left and right mounting brackets are connected to the left and right mounting brackets, respectively, and a cross-sectional shape along the longitudinal direction of the vehicle body includes a support cross member made of a substantially rectangular plate having a long side in the vertical direction. Plant support structure. The left and right mounting brackets include a cross member mounting portion that hangs downward integrally from the bottom surface of the mounting bracket and has a substantially T shape with respect to the bottom surface as viewed from the side of the vehicle body.
2. The power plant support structure according to claim 1, wherein the left and right ends of the support cross member are overlapped and connected to the cross member mounting portion from the front side or the rear side of the vehicle body.   3. The support structure for a power plant according to claim 1, wherein the support cross member has an arc shape in which a middle portion protrudes downward with both left and right ends connected to the mount bracket.   4. The power plant support structure according to claim 1, wherein the support cross member has chamfered portions formed at four corners having a substantially rectangular cross section.

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