JP3597028B2 - Support structure for front differential case - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a front differential case support structure for supporting a differential case (front differential case) at a front portion of a vehicle such as a cab-over type four-wheel drive vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an example of a support structure for a front differential case of this kind, there is one disclosed in Japanese Utility Model Laid-Open No. 6-71248, for example. In this support structure, as shown in FIG. 1, a cross member 2 extending in the vehicle width direction is connected between a pair of side frames 1, 1 arranged on both sides of a front portion of the vehicle, and a front differential is connected to the cross member 2. The front part of the case 3 is supported via a mount rubber 4. The inner ends of the two brackets 5 and 6 are connected to the rear part of the front differential case 3. The outer ends of the brackets 5 and 6 are mounted on the side frames 1 and 1 by mounting rubbers 7 and 8 support.
[0003]
[Problems to be solved by the invention]
Incidentally, it is desired that the front structure of the vehicle body be configured to absorb and reduce the impact force by crashing at the time of a forward collision of the vehicle. In this case, in order to enhance the effect of absorbing and mitigating the impact force, it is necessary to make the crash stroke at the front of the vehicle body as long as possible.
[0004]
However, the support structure of the front differential casing 3 in the above conventional, there the front and rear of the front differential case 3 in structure with firmly supported relative to the frame members of the vehicle such as the cross member 2 and the side frames 1, 1 In addition, since the front differential case 3 itself is made stubbornly, a sufficient crash stroke cannot be secured when the vehicle has a forward collision.
[0005]
Therefore, the front of an object of the present invention, in the case is provided with the front differential case in the front part of the vehicle, by disengaging the rear of the front differential case from the vehicle body, it can take longer crush stroke at the front collision of the vehicle An object of the present invention is to provide a support structure for a differential case.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention is fitted with a pair of left and right sub-frame in a front portion of a vehicle body, a cross member connecting the front portion of the subframe is provided, first the front portion of the front differential case to the cross member And an arm extending in the vehicle width direction is fixed to a rear portion of the front differential case. Both ends of the arm in the vehicle width direction are connected to the sub-frame via a second cylindrical mount rubber. The second cylindrical mounting rubber outer cylinder is fixed to the subframe , the second cylindrical mounting rubber pin is fixed to the arm, and the pin is fixed to the second cylindrical mounting rubber. It is press-fitted from the rear of the vehicle body in the center of the position between the first cylindrical rubber mount and a second cylindrical rubber mount subfolder Over arm bent that bends to the site is provided for, when the front collision of the vehicle, in the bending portion that bends with the body of the front of the second cylindrical rubber mount crashes, the front differential case the vehicle rear And the pin is configured to be displaced rearward with respect to the second cylindrical mount rubber, thereby providing a support structure for a front differential case.
[0007]
When a vehicle equipped with the front differential case of the present invention causes a front collision, the cross member is pushed rearward by an input from the front. At this time, the front differential case is also pushed rearward together with the cross member, but since the pin fixed to the rear of the front differential case via the arm is pulled rearward with respect to the mounting rubber, the rear of the front differential case separates rearward. And a sufficient crash stroke can be secured.
The press-fit direction of the pin does not need to be strictly in the front-rear direction of the vehicle, but may be slightly inclined in the left-right direction or the up-down direction. That is, depending on the direction of input at the time of a frontal collision and the position of the front differential case, the differential case is not necessarily pushed backward, so that the pin may be set in the direction in which the pin can be pulled out most smoothly.
[0008]
In the present invention, the front part and the rear part of the front differential case are respectively supported by using cylindrical mount rubber. In addition to the cylindrical mount rubber, there is also a so-called cushion type mount rubber in the form of a plate.However, the cushion type mount rubber has too high a spring constant and has the disadvantage that the vibration of the front differential case is easily transmitted to the vehicle body. . On the other hand, since the cylindrical mount rubber has a structure in which the rubber is interposed between the outer cylinder and the inner cylinder all around, the degree of freedom in setting the spring constant is high. In the present invention, by supporting the front and rear portions of the front differential case via the cylindrical mount rubber, a suitable spring constant is obtained, and transmission of vibration to the vehicle body can be suppressed.
[0009]
In addition, the cylindrical mount rubber has a rubber portion between the outer cylinder and the inner cylinder, and the pin is pressed into the inner cylinder. However, when the inner cylinder and the pin come into metallic contact, play or slippage occurs. The load may be excessive. Therefore, it is desirable to provide a rubber portion inside the inner cylinder and press-fit a pin into this rubber portion. In this case, backlash during normal use can be eliminated, and the unloading load can be suppressed.
[0010]
According to the present invention, a pair of left and right subframes are attached to the front of the vehicle body, a cross member is provided to connect the front portions of the subframes, and both ends in the vehicle width direction of the arm are attached to the subframe via the cylindrical mount rubber. It is. In this case, since the front differential case is supported by the sub-frame, the front differential case is assembled to the sub-frame in the previous process, and the sub-frame is assembled to the vehicle body frame, whereby the assembling work can be simplified.
Then, a bendable portion is provided at a portion of the subframe located between the first cylindrical mount rubber and the second cylindrical mount rubber, and the second cylindrical mount rubber is provided at the time of a forward collision of the vehicle. The front differential case can be displaced rearward of the vehicle body when the vehicle body in front crashes and the bent portion is bent.
[0011]
Further , a fragile portion for facilitating bending may be provided at the bent portion of the subframe, and the fragile portion may be bent at the time of a forward collision. In this case, the sub-frame is largely deformed in accordance with the crash of the side frame, so that the front differential case can be smoothly separated from the rear.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
2 and 3 show an example of a support structure for a front differential case according to the present invention.
The support structure of the front differential case of this embodiment is applied to a cab-over type four-wheel drive vehicle, and the arrow Fr indicates the front of the vehicle .
[0013]
A pair of side frames 10, 10 extending in the front-rear direction of the vehicle body are disposed at both side positions at the front of the vehicle. As shown in FIG. 3, a sub-frame 11 is fastened to the lower surfaces of the side frames 10 and 10 by bolts 12. The sub-frame 11 is formed, for example, in a substantially H-shape in plan view, and connects a pair of side portions 11 a extending substantially in the vehicle longitudinal direction substantially along the side frame 10 to each other, and connecting the front portions of the side portions 11 a to each other. And a cross portion 11b. Both front and rear ends of the side portion 11 a are fastened to the side frame 10 by the bolts 12. The side portion 11a of the sub-frame 11 is bent downward as shown in FIG. 3, and a fragile portion 11c that is easily bent at the time of a forward collision of the vehicle is formed at a bent portion slightly behind the joint portion with the cross portion 11b. Have been.
The side portion 11a can also be used for supporting one end of a suspension arm (not shown) of a front suspension. Further, a cross member 13 is bridged and fixed between the side frames 10 and 10 at the rear of the sub frame 11, and the rear end of the sub frame 11 is located near a connecting portion between the cross member 13 and the side frame 10. Has been concluded.
[0014]
A front differential case 15 is mounted on the sub-frame 11. The front differential case 15 contains a differential gear for transmitting the rotational force of the probe shaft 16 to the axle 17. In this embodiment, the structure is applied to a cab-over type vehicle, and the front differential case 15 is offset from the central position in the vehicle width direction by an appropriate dimension L to one side in the vehicle width direction. The front portion of the front differential case 15 is connected to the cross portion 11b of the sub-frame 11 via a cylindrical mount rubber 18 and a bracket 19. In this case, a bolt 20 penetrating through the mount rubber 18 is fixed to the bracket 19 in the vehicle width direction.
[0015]
An arm 22 extending in the vehicle width direction is fixed to a rear portion of the front differential case 15 via a bracket 21. In this embodiment, the arm 22 is formed using a cylindrical pipe material, for example, from the viewpoint of weight reduction. Pins 23 and 24 projecting forward are fixed to both ends of the arm 22, respectively. In this embodiment, a single continuous arm 22 is used, but two arms 22 may be attached to the rear of the front differential case 15.
[0016]
The pins 23 and 24 are pressed into cylindrical mount rubbers 25 and 26 fixed to the side portions 11a of the sub-frame 11 from the rear of the vehicle body. That is, as shown in FIG. 4, the cylindrical mount rubbers 25 and 26 are formed of an outer cylinder 25a fixed to the side portion 11a, an inner cylinder 25b, and a rubber interposed between the outer cylinder 25a and the inner cylinder 25b. 25c, and a rubber portion 25d is fixed inside the inner cylinder 25b. Note that the rubber portion 25d may be formed integrally with the rubber 25c. Since the pins 23 and 24 are press-fitted inside the rubber portion 25d, the play between the inner cylinder 25b and the pins 23 and 24 can be absorbed, and the load of the pins 23 and 24 coming off can be set low.
[0017]
Since the pins 23 and 24 are press-fitted into the mount rubbers 25 and 26 from the rear of the vehicle body as described above, when the front collision occurs, the pins 23 and 24 are displaced rearward as the front differential case 15 is displaced rearward. The rear part of the front differential case 15 can be detached from the mount rubbers 25 and 26 rearward .
In the case where the front differential case 15 as described above is offset to one side from the body center position, does not necessarily left and right pins 23 and 24 during a frontal collision moves immediately behind both the front differential case 15 The direction of the pins 23 and 24 may be slightly inclined in the left-right direction or the up-down direction in consideration of the displacement characteristics.
[0018]
Next, the operation of the front differential case support structure having the above configuration will be described.
The front portion of the front differential case 15 is supported by the cross portion 11b of the sub-frame 11 via a cylindrical mount rubber 18, and the rear portion of the front differential case 15 is supported by the sub-frame via cylindrical mount rubbers 25 and 26. Since it is supported by the side portion 11a of the eleventh portion, a suitable spring constant is obtained by the action of the mount rubbers 18, 25, 26, and the transmission of the vibration of the front differential case 15 to the vehicle body can be suppressed. Further, since the support bolt 20 of the front mounting rubber 18 is arranged in the horizontal direction, the front portion of the front differential case 15 does not come off, while the rear mounting rubber 25, 26 has the pin 23, Since the pin 24 is press-fitted from the rear, there is no possibility that the pins 23 and 24 fall out of the mount rubbers 25 and 26 in response to a load input (vehicle width direction) during normal running.
[0019]
The front differential case 15 has a front portion attached to the cross portion 11b in front of the weak portion 11c of the subframe 11, and a rear portion of the front differential case 15 behind the weak portion 11c via the arm 22. Is supported by the side portion 11a.
[0020]
When the vehicle causes a forward collision as shown in FIGS. 5 and 6, the impact force F acts on the front portion of the side frame 10, the side frame 10 crashes, and the impact force F also acts on the sub-frame 11. The front part of the sub-frame 11, especially the cross part 11b, is displaced rearward. Therefore, the front differential case 15 connected to the cross portion 11b is also displaced rearward. On the other hand, since the rear end of the sub-frame 11 is connected to the portion of the side frame 10 that does not crash, the sub-frame 11 is bent at the fragile portion 11c, and the cylindrical mount rubbers 25, 26 fixed to the side portion 11a. Tries to hold that position. As a result, the arm 22 connected to the rear part of the front differential case 15 moves relatively rearward with respect to the mounting rubbers 25, 26, and the pins 23, 24 detach from the mounting rubbers 25, 26 rearward. . Therefore, the front differential case 15 can be freely displaced rearward, the crash stroke at the front of the vehicle can be lengthened, and the shock absorbing effect can be enhanced. Incidentally, the propeller shaft 16 at the time of withdrawal of the front differential case 15 so as to be detached from the front differential case 15, it may be caused to break the connection pins of the propeller shaft 16.
[0022]
【The invention's effect】
As is apparent from the above description, according to the present invention, the front and rear portions of the front differential case are supported on the vehicle body using the cylindrical mounting rubber. A vibration absorbing effect can be exhibited.
Further, a bendable portion is provided at a portion of the sub-frame located between the first cylindrical mount rubber and the second cylindrical mount rubber, so that the second cylindrical mount rubber is provided with Since the front vehicle body crashes and the bent portion bends, the front differential case is displaced rearward of the vehicle body, and the pin is configured to be disengaged rearward with respect to the second cylindrical mount rubber. The front differential case does not hinder the crash, and the crash stroke can be lengthened.
[Brief description of the drawings]
FIG. 1 is a plan view of an example of a conventional support structure for a front differential case.
FIG. 2 is a plan view showing an example of a support structure for a front differential case according to the present invention.
FIG. 3 is a side view of FIG. 2;
FIG. 4 is an enlarged sectional view of a portion A in FIG. 2;
5 is a plan view of the front differential case support structure shown in FIG. 2 at the time of a crash.
FIG. 6 is a side view of FIG. 5;
[Explanation of symbols]
10 Side frame 11 Sub frame 11a Side part 11b Cross part (cross member)
11c Fragile part 15 Front differential case 18, 25, 26 Mount rubber 22 Arm 23, 24 pin

Claims (2)

Attaching a pair of left and right sub-frame in a front portion of a vehicle body, a cross member connecting the front portion of the subframe is provided, the front portion of the front differential case linked via a first cylindrical rubber mount to the cross member, An arm extending in the vehicle width direction is fixed to a rear portion of the front differential case, and both ends of the arm in the vehicle width direction are attached to the subframe via a second cylindrical mount rubber.
An outer cylinder of the second cylindrical mounting rubber is fixed to the subframe , a pin of the second cylindrical mounting rubber is fixed to the arm, and the pin is mounted on the center of the second cylindrical mounting rubber. Press-fit from behind,
A bendable portion is provided at a portion of the subframe located between the first cylindrical mount rubber and the second cylindrical mount rubber,
At the time of a forward collision of the vehicle, the vehicle body ahead of the second cylindrical mount rubber crashes and the bent portion is bent, so that the front differential case is displaced rearward of the vehicle body, and the pin is moved to the second cylindrical mount rubber. A support structure for a front differential case, wherein the support structure is configured to be disengaged rearward with respect to the front case. The support structure for a front differential case according to claim 1 , wherein the bent portion is provided with a fragile portion that facilitates bending .

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