JP2012224152A - Vehicle body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vehicle body structure that can suppress a vibration of a subframe.SOLUTION: The vehicle body structure 10 includes: a subframe 14 which is attached to a front side member 12 forming a vehicle framework while supporting a lower control arm 22 that configures a front suspension; and a cooling unit 40 which is configured to incorporate a heat exchanger 44 exchanging heat between air and a refrigerant. Further, the cooling unit 40 is attached to the subframe 14 and functions as a mass damper or a dynamic damper.

Description

  The present invention relates to a vehicle body structure provided with a subframe.

  A technique is known in which a radiator is elastically supported by a radiator support, and the radiator functions as a dynamic damper for a vehicle body (see, for example, Patent Document 1).

JP 2005-319959 A

  Incidentally, there is a demand for suppressing vibration of a subframe in a vehicle including a subframe that supports wheels via a suspension.

  An object of the present invention is to obtain a vehicle body structure that can suppress vibration of a subframe.

  A vehicle body structure according to a first aspect of the present invention includes a subframe that is attached to the vehicle body and includes a subframe that supports at least a part of the suspension, and a heat exchanger of air and refrigerant, and is attached to the subframe. And.

  In the vehicle body structure according to the first aspect, the subframe that supports at least a part of the suspension is vibrated by the input from the road surface (wheel). Here, in this vehicle body structure, since the cooling unit is attached to the subframe, the cooling unit functions as a mass damper or a dynamic damper, and the vibration of the subframe is suppressed.

  Thus, in the vehicle body structure according to the first aspect, the vibration of the subframe can be suppressed. As the heat exchanger constituting the cooling unit, for example, one or both of a radiator that uses cooling water as a refrigerant to cool the vehicle drive source and a condenser that condenses the refrigerant of the air conditioner can be used.

  A vehicle body structure according to a second aspect of the present invention is the vehicle body structure according to the first aspect, further comprising a steering gear box for turning a wheel fixed to the subframe and supported by the suspension. At least a part of the unit is attached to the subframe via the steering gear box.

  In the vehicle body structure according to the second aspect, a steering gear box for turning the wheel supported by the suspension is fixed to the subframe. Since at least a part of the cooling unit is attached to the subframe via the steering gear box, the cooling unit has a high degree of freedom with respect to the dimensional shape and mounting orientation of the cooling unit as a whole. That is, it is easy to connect the cooling unit to the subframe.

  A vehicle body structure according to a third aspect of the present invention is the vehicle body structure according to the first or second aspect, wherein the sub-frame is elongated in the vehicle width direction and a lower portion of the cooling unit is attached. The member includes a second cross member that is long in the vehicle width direction and is disposed in front of and above the vehicle with respect to the first cross member.

  In the vehicle body structure according to the third aspect, the lower part of the cooling unit is connected to the first cross member located on the rear side of the pair of front and rear cross members. Since the second cross member located on the front side is offset upward with respect to the first cross member, that is, the lower part of the cooling unit, an air flow introduction path to the heat exchanger of air and refrigerant is secured.

  As described above, the vehicle body structure according to the present invention has an excellent effect that vibration of the subframe can be suppressed.

It is a disassembled perspective view which shows the vehicle body structure which concerns on embodiment of this invention. It is a side view which shows the vehicle body structure which concerns on embodiment of this invention. 1 is a side sectional view showing a vehicle body structure according to an embodiment of the present invention. It is a front view which shows the vehicle body structure which concerns on embodiment of this invention.

  A vehicle body structure 10 according to an embodiment of the present invention will be described with reference to FIGS. Note that an arrow FR appropriately shown in the drawing indicates a forward direction in the vehicle longitudinal direction, an arrow UP indicates an upward direction in the vehicle vertical direction, and an arrow W indicates a vehicle width direction. In the following description, when using the front-rear direction and the up-down direction unless otherwise specified, the vehicle front-rear direction and the vehicle up-down direction are indicated.

  FIG. 1 is an exploded perspective view showing the overall structure of the vehicle body structure 10. 2 shows a side view of the vehicle body structure 10, and FIG. 4 shows a front view of the vehicle body structure 10. As shown in FIG. As shown in these drawings, the vehicle body structure 10 constitutes a front portion of the automobile V. The automobile V includes a pair of left and right front side members 12 (only the right front side member 12 is shown in FIG. 1) as a vehicle body. Each front side member 12 is a skeleton member that is long in the front-rear direction. As shown in FIG. 2, the front end is bridged by a bumper reinforcement 13 and the rear portion 12R is joined to the lower surface side of the floor panel 36. . Each of the front side members 12 has a kick portion 12K formed at an intermediate portion thereof, and the difference in height between the front portion 12F and the rear portion 12R is absorbed.

  The vehicle body structure 10 also includes a subframe (suspension member) 14 that supports a front suspension that supports a front wheel Wf as a wheel. As shown in FIG. 1, the subframe 14 includes a pair of left and right side rails 16, a rear cross member 18 serving as a first cross member that bridges between rear ends of the left and right side rails 16, and left and right side rails 16. A front cross member 20 as a second cross member that spans between the front portions is configured as a main portion. That is, the subframe 14 is a well-shaped frame having a substantially rectangular frame shape in plan view.

  In this embodiment, the front portion of each side rail 16 has a bifurcated structure having a lower portion 16L that forms a straight line from the rear portion in the front-rear direction and an upper portion 16U that is spaced above and below the lower portion 16L. ing. The lower portion 16L and the upper portion 16U of each side rail 16 are connected by a connecting wall 16W in which a lightening hole 16H is formed. Each side rail 16 supports the inner end in the vehicle width direction of the lower arm 22 constituting the front suspension by the rear end (near) and the lower portion 16L so that the side rail 16 can swing about an axis along the front-rear direction. . Although illustration is omitted, the lower arm 22 is connected to an axle bracket that rotatably supports the hub of the front wheel Wf. On the other hand, the front cross member 20 bridges between the upper portions 16U of the side rails 16.

  These side rails 16 are attached to a mounting portion 12C provided on the front portion 12F of the front side member 12 via a bracket 24 provided on the front end (near) of the upper portion 16U with a fastener 21 such as a bolt or a nut. It can be attached. Moreover, although illustration is abbreviate | omitted, each side rail 16 is attached to the rear part (near the lower end part of the kick part 12K) of the front side member 12 in the rear end. As these attachment structures, either rigid connection by a fastening means (non-vibration isolation structure) or elastic coupling (anti-vibration structure) in which an anti-vibration rubber is interposed in the fastening portion can be adopted.

  Further, as shown in FIG. 3 as a cross-sectional view at the center in the vehicle width direction, the subframe 14 supports a power unit 26 for driving the front wheels Wf. The power unit 26 in this embodiment includes an engine that is an internal combustion engine and an electric motor as drive sources. Therefore, the vehicle V is a hybrid vehicle having two drive sources. Specifically, the power unit includes a horizontal engine having a crankshaft along the vehicle width direction and a transaxle connected to the engine so as to be able to transmit power. The transaxle includes an electric motor, a generator (not shown), a power split mechanism, a transmission such as a continuously variable transmission, and the like. In this embodiment, the transaxle includes, for example, an electric motor, a generator, and an inverter electrically connected to a battery. Therefore, the power unit according to this embodiment can also be regarded as a power plant. The transaxle may be a normal transaxle such as a manual transmission (MT), a torque converter type automatic transmission (AT), a continuously variable transmission (CVT), or the like. A drive shaft (not shown) which is an output shaft of the power unit 26 is connected to the hub of the front wheel Wf so as to be able to transmit a driving force.

  The power unit 26 described above is supported by a vehicle body (front side member 12) via a mount member at a portion not shown, and is connected to the subframe 14 via a torque rod 28 as shown in FIG. The torque rod 28 is configured such that a pair of coupling portions each formed by filling rubber between the inner cylinder and the outer cylinder are connected by a rod, and the front cross member 20 and the power unit 26 of the subframe 14 are connected. And are connected elastically. The torque rod 28 is configured to suppress displacement (vibration) around the roll axis along the vehicle width direction of the power unit 26.

  As shown in FIGS. 1 and 2, a steering gear box (steering gear housing) 30 is fixed to the subframe 14. The steering gear box 30 is for turning the left and right front wheels Wf, and although not shown, is connected to a knuckle arm of the front wheel Wf via a tie rod. The steering gear box 30 is connected to a steering wheel (not shown) via a steering shaft 32. The operation force of the steering wheel by the occupant is transmitted to the steering gear box 30 via the steering shaft 32, and the assisting force by the steering gear box 30 is applied and transmitted to the front wheels Wf as the steering force. Note that the steering gear box 30 may provide a turning force to the left and right front wheels Wf based on an electrical signal generated by steering the steering wheel.

  The steering gear box 30 has mounting pieces 30C projecting from two places separated from each other in the longitudinal direction substantially coincident with the vehicle width direction. The mounting pieces 30C are provided on the front cross member 20 at the respective mounting pieces 30C. It is fastened and fixed by fasteners 31 such as bolts and nuts. Thus, the steering gear box 30 is fixed to the subframe 14 and forms a structure (vibration system) that is integral with the subframe 14. In this state, the steering gear box 30 is offset above the front cross member 20 of the sub-frame 14 as shown in FIG. In this embodiment, the steering gear box 30 is located behind the front cross member 20 and is disposed closer to a cooling unit 40 described later than the front cross member 20.

  In the vehicle V to which the vehicle body structure 10 is applied, a power unit room (engine room) Rp in which the power unit 26 and the like are arranged and a passenger compartment C are partitioned by a dash panel 34. The dash panel 34 is joined to the front end portion of the floor panel 36. In the center of the floor panel 36 in the vehicle width direction, a floor tunnel 38 having a “U” shape is formed which opens downward in the vehicle vertical direction in a front sectional view. The front end of the floor tunnel 38 is an open end 38 </ b> A that opens forward in the lower portion 34 </ b> L of the dash panel 34. In this embodiment, the lower portion 34L of the dash panel 34 is inclined with respect to the flat upper portion 34U substantially along the vertical direction so that the front side is higher than the rear side, and the floor tunnel 38 is formed at the inclined portion. Open forward.

  As shown in FIG. 1, the vehicle body structure 10 includes a cooling unit 40. As shown in FIGS. 2 and 3, the cooling unit 40 is disposed so as to close the opening end 38 </ b> A of the floor tunnel 38. Therefore, in this embodiment, the cooling unit 40 is disposed on the rear side in the vehicle front-rear direction with respect to the power unit 26. The cooling unit 40 includes an air / refrigerant heat exchanger 44. The heat exchanger 44 is a radiator that is an air-cooled heat exchanger that circulates cooling water as a refrigerant between the power unit 26 (engine and electric motor thereof) and cools the power unit 26, and an air conditioner (not shown) Of at least one condenser (condenser) that is a heat exchanger for the air-conditioning refrigerant with the air constituting the refrigeration cycle) (both in this embodiment).

  As shown in FIG. 3, the cooling unit 40 includes a fan 42 provided on the rear surface side of the heat exchanger 44 and a fan shroud 45 covering the space between them. By the operation of the fan 42 or the traveling of the automobile V, the cooling air passing through the cooling unit 40 from the front side to the rear side passes through the heat exchange with the refrigerant (cooling water or air conditioning refrigerant). Yes. The cooling air after heat exchange with the refrigerant is discharged from the fan shroud 45 to the bottom of the floor through the downward opening end 38B of the floor tunnel 38. Therefore, the fan shroud 45 is disposed in the floor tunnel 38.

  Cooling air is introduced into the cooling unit 40 from below the floor of the automobile V. Specifically, as shown in FIG. 3, the vehicle body structure 10 includes an under cover 46 that covers the power unit chamber Rp from below, and the under cover 46 supplies cooling air to the heat exchanger 44 of the cooling unit 40. A guiding duct 48 is provided. That is, the duct 48 has a rear opening end 48B that sandwiches the cooling unit 40 between the air intake opening 48A opening toward the road surface in front of the heat exchanger 44 and the opening end 38A of the floor tunnel 38 in a substantially airtight state. A flow path is formed between the two.

  The cooling unit 40 described above is attached to the subframe 14. Specifically, a plurality (two in this embodiment) of mounting bolts 50 protrude downward from the lower end of the cooling unit 40 (heat exchanger 44). A plurality of mounting pieces 52 are provided on the rear cross member 18 so as to be spaced apart from each other in the vehicle width direction corresponding to the plurality of mounting bolts 50. A lower mounting portion Jb (see FIG. 2) in which the lower portion of the cooling unit 40 is attached to the rear cross member 18 is configured by screwing the nuts 54 into the mounting bolts 50 penetrating the mounting pieces 52.

  On the other hand, the upper part of the cooling unit 40 is attached to the steering gear box 30. Specifically, as shown in FIG. 1, a plurality (two in this embodiment) of mounting pieces 56 project forward from the upper end of the cooling unit 40 (heat exchanger 44). The steering gear box 30 is provided with a plurality of mounting brackets 58 corresponding to the plurality of mounting pieces 56.

  As shown in FIG. 2, the upper portion of the cooling unit 40 is attached to the steering gear box by the mounting pieces 56 and the bolts 60 penetrating the mounting brackets 58 and the nuts 62 screwed into the bolts 60. 30 is attached. That is, an upper attachment portion Jt (see FIG. 2) is configured in which the upper portion of the cooling unit 40 is attached to the steering gear box 30 via the attachment bracket 58.

  The lower mounting portion Jb and the upper mounting portion Jt are rigidly coupled (non-vibration-proof structure) by the mounting bolt 50, the nut 54, the bolt 60, and the nut 62 described above, and elastic coupling in which a vibration-proof rubber is interposed in the fastening portion. Any of (anti-vibration structure) can be adopted. The cooling unit 40 functions as a mass damper in a configuration rigidly connected to the subframe 14 and functions as a dynamic damper in a configuration elastically coupled to the subframe 14. In the latter case, the elastic characteristics (spring constant) of the vibration-proof rubber and the like are set so that the cooling unit 40 functions as a dynamic damper for the subframe 14 at a specific frequency.

  In the vehicle body structure 10 described above, the suspension including the subframe 14, the lower arm 22, the front wheels Wf (including the hub, axle bracket, knuckle arm, etc.), the power unit 26, the torque rod 28, the steering shaft 32, and the cooling unit 40 are provided. Before being mounted on the vehicle body (front side member 12, dash panel 34, floor panel 36), it is modularized as a front module 64 (see FIG. 2). The front module 64 may include an under cover 46 (duct 48).

  Next, the operation of this embodiment will be described.

  In the vehicle V to which the vehicle body structure 10 having the above configuration is applied, the driving force generated by the power unit 26 is transmitted to the front wheels Wf to travel. Further, the front wheel Wf is steered by transmitting the steering force of the occupant to the front wheel Wf while being assisted through the steering gear box 30. During traveling of the automobile V, cooling water circulates between the power unit 26 and the heat exchanger 44 of the cooling unit 40. The cooling water is cooled by heat exchange with air in the cooling unit 40. Further, when the air conditioner is operated, the refrigerant circulates in the order of the heat exchanger 44, the expansion valve, the evaporator, and the compressor of the cooling unit 40 to form a refrigeration cycle. The cooling unit 40 functions as a condenser that cools and condenses the refrigerant by heat exchange with air.

  The heat exchange in the cooling unit 40 is performed by the running air of the automobile V or the air flow (cooling air) generated by the operation of the fan 42 flowing through the air-side flow path of the cooling unit 40. For example, when the vehicle speed of the automobile V is equal to or lower than a predetermined vehicle speed and the cooling water temperature is equal to or higher than a predetermined temperature, the fan 42 is operated by a cooling ECU (not shown). Then, it is led to the cooling unit 40 by the suction force of the fan 42. For example, when the vehicle speed of the automobile V exceeds a predetermined vehicle speed, the fan 42 is stopped by the cooling ECU. Then, the traveling wind of the automobile V is guided to the cooling unit 40.

  As the automobile V travels, fluctuations (load, displacement) are input from the road surface to the subframe 14 via the front wheels Wf and the lower arm 22. Due to the input from the road surface, the sub-frame 14 is vibrated.

  Here, in the vehicle body structure 10 in which the cooling unit 40 is attached to the subframe 14 without vibration isolation (rigidly coupled), the cooling unit 40 functions as a mass damper. That is, since the mass of the cooling unit 40 is added as the mass of the vibration system of the subframe 14, the resonance frequency of the vibration system of the subframe 14 is shifted to the low frequency side. As a result, the resonance frequency of the vibration system of the subframe 14 is shifted from the frequency that causes a problem in the input from the road surface, and the vibration of the subframe 14 is suppressed.

  Further, in the vehicle body structure 10 in which the cooling unit 40 is attached to the subframe 14 with vibration isolation (elastically coupled), the cooling unit 40 functions as a dynamic damper. That is, the vibration of the frequency which becomes a problem in the vibration system of the subframe 14 is absorbed by the vibration of the cooling unit 40 which is a mass element in the sub vibration system formed by the cooling unit 40. Therefore, the vibration of the subframe 14 is also suppressed in this configuration.

  Thus, in the vehicle body structure 10 according to the present embodiment, the vibration of the subframe 14 can be suppressed. Supplementally, relying on reinforcement by using the cooling unit 40 as a mass damper or a dynamic damper in a configuration in which exhaust pipes and other parts are closely arranged and it is difficult to create a structure (reinforcement) that directly receives input from the road surface. And vibration of the subframe 14 can be suppressed.

  In the vehicle body structure 10, the upper part of the cooling unit 40 is connected to the subframe 14 via the steering gear box 30. For this reason, the cooling unit 40 can be connected to the subframe 14 with a simple structure. That is, by using the steering gear box 30 located above the subframe 14, the mounting bracket 58 can be downsized and the shape can be simplified as compared with the configuration in which the upper part of the cooling unit 40 is connected to the subframe 14. It becomes possible to become. In other words, compared to the configuration in which the cooling unit 40 is connected to the subframe 14 as a whole, the cooling unit 40 has a higher degree of freedom with respect to the dimensional shape and mounting orientation, and the cooling unit 40 can be easily connected to the subframe 14.

  Furthermore, in the vehicle body structure 10, since the vibration of the subframe 14 is suppressed without depending on the reinforcing structure or the like as described above, the degree of freedom with respect to the size and shape of the subframe 14 is also increased. For this reason, in the sub-frame 14, the front cross member 20 can be formed to be offset upward with respect to the rear cross member 18. With this shape, a cooling air introduction path to the cooling unit 40 through the duct 48 is secured.

  For example, in the configuration according to the comparative example provided with the front cross member that is located at the same height as the rear cross member 18 (over the left and right lower portions 16L), the front cross member crosses the central portion of the air intake port 48A. The introduction of cooling air into the duct 48 is limited. On the other hand, in the vehicle body structure 10, the front cross member 20 is offset upward as shown in FIGS. 3 and 4. For this reason, as shown by an arrow F in FIG. 3, a cooling air introduction path from below the floor to the cooling unit 40 is secured.

  Furthermore, in the vehicle body structure 10, the suspension including the subframe 14, the lower arm 22, the front wheel Wf, the power unit 26, the torque rod 28, the steering shaft 32, the cooling unit 40 and the like are modularized as a front module 64 before being mounted on the vehicle body. Has been. For this reason, each said part can be mounted in a vehicle body integrally, and mounting property is high.

  In the above-described embodiment, an example in which the cooling unit 40 is attached to the sub-frame 14 via the steering gear box 30 has been described. However, the present invention is not limited to this, and for example, a high-level arrangement disposed at a higher position. In the configuration including the mount type steering gear box, a configuration in which the upper portion (mounting piece 56) of the cooling unit 40 is mounted on a mounting bracket provided on the front cross member 20 may be employed.

  Further, in the above-described embodiment, the example in which the cooling air to the heat exchanger 44 is introduced from the air intake port 48A below the floor is shown, but the present invention is not limited thereto, and is formed, for example, at the lower part of the front bumper. The path of the cooling air along the front-rear direction from the opening to the heat exchanger 44 through the lower side of the power unit 26 may be set instead of or in addition to the cooling air introduction path from below the floor. The cooling air from the lower portion of the front bumper can be efficiently guided to the heat exchanger 44 by the configuration in which the front cross member 20 is offset upward as shown in FIG.

  Furthermore, in the above-described embodiment, an example in which the cooling unit 40 includes the heat exchanger 44 as a radiator and an air conditioning condenser has been described. However, the present invention is not limited to this, and the function of only one of the radiator and the air conditioning condenser is provided. It is good also as a structure which connects the heat exchanger 44 which has to the sub-frame 14. FIG.

  Furthermore, in the above-described embodiment, the example in which the power unit 26 including the internal combustion engine and the motor is disposed in the power unit chamber Rp located in front of the vehicle compartment C is shown, but the present invention is not limited to this, for example, The power unit 26 may be configured so as not to include a motor (general FF vehicle, FR vehicle, 4WD vehicle or other engine vehicle), and the power unit 26 including the internal combustion engine is disposed in the power unit chamber located behind the passenger compartment C. It is good also as a structure, and it is good also as a structure in which a power unit does not contain an internal combustion engine.

  In addition, the present invention is not limited to the configuration of the above-described embodiment, and it is needless to say that various modifications can be made without departing from the scope of the invention.

10 Car body structure 12 Front side member 14 Sub frame 18 Rear cross member (first cross member)
20 Front cross member (second cross member)
22 Lower arm (suspension)
30 Steering gear box 40 Cooling unit Wf Front wheel

Claims (3)

A subframe attached to the vehicle body and supporting at least a part of the suspension;
A cooling unit including a heat exchanger for air and refrigerant, and attached to the subframe;
Body structure with A steering gear box for turning a wheel fixed to the subframe and supported by the suspension;
The vehicle body structure according to claim 1, wherein at least a part of the cooling unit is attached to the sub-frame via the steering gear box. The subframe is:
A first cross member that is elongated in the vehicle width direction and to which a lower portion of the cooling unit is attached;
A second cross member that is longitudinal in the vehicle width direction and disposed in front of and above the vehicle with respect to the first cross member;
The vehicle body structure according to claim 1 or 2, wherein the vehicle body structure is configured to include

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