JP3999019B2 - Front suspension device for low floor bus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a front axle having a front axle suspended by an air spring, and includes an upper rod disposed in a front-rear direction between a chassis frame and the front axle and a lower rod disposed in a V shape. More particularly, the present invention relates to a front suspension device for a low floor bus that further suppresses the occurrence of axle steer when an external force is input to a front wheel while traveling and further improves traveling stability.
[0002]
[Prior art]
As shown in FIGS. 5 and 6, a conventional front suspension device for a low floor bus is disposed below a chassis frame 3 including a pair of left and right side rails 1, 1 extending in the longitudinal direction of the vehicle and a plurality of cross members 2. The front axle 5 is provided and suspended by air springs 4 and 4, and one end is pivotally attached to the cross member 2 of the chassis frame 3, and the other end is pivotally attached to both sides of the front axle 5 and arranged in the front-rear direction. The left and right upper rods 6, 6, and one end pivotally attached to the cross member 2 of the chassis frame 3 and the other end pivotally attached to the substantially central portion of the front axle 5 are arranged in a V shape. It consisted of a lower rod 7,7. Note that left and right front wheels 8, 8 are attached to both ends of the front axle 5 via knuckles (not shown). 5 and 6, the direction of arrow A indicates the front of the vehicle.
[0003]
In such a front suspension device, the air spring 4 that suspends the front axle 5 acts as a soft spring effective in improving the riding comfort in the vertical direction, but the relative position between the front axle 5 and the chassis frame 3 is determined. The function of regulating the vehicle longitudinal direction and the vehicle width direction is generally weak. Therefore, the relative position in the vehicle front-rear direction between the front axle 5 and the chassis frame 3 is regulated by the upper rod 6 as a radius rod, and the relative position in the vehicle width direction by a V-shaped lower rod 7 as a lateral rod. Is to regulate.
[0004]
[Problems to be solved by the invention]
However, in such a conventional low floor bus front suspension device, since the two lower rods 7 are arranged in a V shape and the other end is pivotally attached to the substantially central portion of the front axle 5, For example, if one wheel rides on something and a force in the direction of arrow F is input to the front wheel 8 on one side (left side in FIG. 5) from the front, the upper rod 6 (FIG. 6) is near the input portion. However, there is no member that receives the force at the bottom, and the front axle 5 may be rotated. That is, a so-called axle that rotates the front axle 5 in the directions of arrows B and C around the apex portion in which the two lower rods 7 are arranged in a V shape and pivotally attached to the substantially central portion of the front axle 5. There was a slight occurrence of steer.
[0005]
When such an axle steer occurs, a force that rotates the front axle 5 in the directions of the arrows B and C works separately from the steering operation of the steering device, and the direction of the front wheel 8 may slightly change. It was.
[0006]
The simulation results for the generation of such axle steer are shown in FIGS. FIG. 7A shows a conventional front suspension device as a simulation model. That is, the model Ma includes two upper rods 6 and 6 on the left and right sides, and two lower rods 7 and 7 that are pivotally attached to the substantially central portion of the front axle 5 and arranged in a V shape. Yes. Reference numeral 9 denotes a drag link of a steering link mechanism connected to the front axle 5.
[0007]
FIG. 8 is a graph showing a simulation result when an external force F at the time of riding on one wheel step is inputted to one front wheel 8 for the above model Ma, and the horizontal axis is a front axle due to an axle steer generated when riding on one wheel step. 5 indicates the amount of deviation in the X direction (front-rear direction), and the vertical axis indicates the angular difference of the front axle 5 at that time. When the conventional front suspension device is a model Ma, as shown by an elliptical area in the upper right part of FIG. 8, the amount of deviation of the front axle 5 in the X direction is large and the angle difference is also large. Therefore, the generation of axle steer could not be suppressed so much.
[0008]
In view of the above, the present invention addresses the above-described problems and provides a front suspension device for a low floor bus that further improves driving stability by suppressing the occurrence of axle steer when an external force is input to the front wheels while traveling. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a front suspension apparatus for a low floor bus according to the present invention comprises a front axle disposed below a chassis frame and suspended by an air spring, one end pivotally attached to the chassis frame and the other end. Are pivotally attached to both sides of the front axle and are arranged in the front-rear direction. Two left and right upper rods, one end pivotally attached to the chassis frame and the other end pivotally attached to a substantially central portion of the front axle. A front suspension apparatus for a low floor bus, comprising two lower rods arranged in a letter shape, and one end of the lower rod attached to the chassis frame in the same plane as the mounting plane of the two lower rods the door Rukuroddo other end of which is arranged in the longitudinal direction are pivotally attached to the front axle while being pivotally mounted in the vicinity of the front axle The one side is a steering linkage connected against those provided one only on the opposite side.
[0010]
With such a configuration, one end is pivotally attached to the chassis frame, and the other end is pivotally attached to the substantially central portion of the front axle, and the front and rear are within the same plane as the mounting plane of the two lower rods arranged in a V shape. something bets Rukuroddo arranged in a direction, the one side portion of the steering linkage is connected to the front axle by providing one only on the opposite side, by the torque rod, is in the running example one wheel When an external force is input from the front of the vehicle, it receives the force at the input portion and opposes the axle steer that tries to rotate the front axle. In addition, by providing only one torque rod that opposes this axle steer only on the side opposite to the one side to which the steering link mechanism is connected, it effectively resists axle steer and simplifies the structure and reduces costs. Reduce .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic plan view showing an embodiment of a front suspension apparatus for a low floor bus according to the present invention, and FIG. 2 is a left side view thereof. This front suspension device is applied to a low-floor bus in which the height of the passenger compartment floor from the ground surface is set low so as to be convenient for getting on and off of infants, elderly people, wheelchair users, etc. It has two upper rods 6, 6 and two lower rods 7, 7, and further includes one torque rod 11. 1 and 2, the direction of arrow A indicates the front of the vehicle.
[0014]
In FIG. 1, a front axle 5 supports the load of the left and right front wheels 8 and 8 and serves to steer. The front axle 5 includes a pair of left and right side rails 1 and 1 extending in the longitudinal direction of the vehicle and a plurality of cross members 2. It is disposed below the chassis frame 3 and is suspended by air springs 4 and 4. The front axle 5 is applied to a low-floor bus. As shown in FIG. 3, the center portion is bent downward in a front view and is formed in a substantially inverted hat shape. The left and right front wheels 8, 8 are mounted on the knuckle 12. Moreover, in FIG. 3, the code | symbol 13 has shown the vehicle interior floor.
[0015]
Two left and right upper rods 6, 6 are stretched on the upper portion between the front axle 5 and the cross member 2 on the front side of the front axle 5. The upper rod 6 is a radius rod that regulates the relative position of the front axle 5 and the chassis frame 3 in the longitudinal direction of the vehicle. One end of the upper rod 6 is pivotally attached to the cross member 2 on the front side of the chassis frame 3. And the other end is pivotally attached to both sides of the front axle 5 and arranged in the front-rear direction. As shown in FIG. 1, the front end of the upper rod 6 is pivotally attached to a bracket 14 fixed to the front cross member 2 by means of a bolt via a rubber bush, and the rear end is formed on both sides of the front axle 5. The bracket is fixed to the bracket by a bolt through a rubber bush.
[0016]
Two lower rods 7 and 7 are stretched at the lower part between the front cross member 2 and the front axle 5 of the front axle 5. The lower rod 7 is a lateral rod that regulates the relative position of the front axle 5 and the chassis frame 3 in the vehicle width direction. One end of the lower rod 7 is pivotally attached to the cross member 2 on the front side of the chassis frame 3. And the other end is pivotally attached to the substantially central portion of the front axle 5 and arranged in a V shape. As shown in FIG. 1, the front end of the lower rod 7 is pivotally attached to a bracket 15 fixed to the front cross member 2 by means of a bolt through a rubber bush, and the rear end thereof is a central portion of the front axle 5. The bracket 16 is pivotally attached to the common bracket 16 by a bolt through a rubber bush.
[0017]
In FIG. 1, reference numeral 17 denotes a tie rod that connects knuckles (not shown) coupled to both ends of the front axle 5.
[0018]
Here, in the present invention, at least one torque rod 11 is additionally provided in the same plane as the mounting plane of the two lower rods 7 and 7. This torque rod 11 receives the force at the input part when an external force F is input from the front, for example, when one wheel rides on something while the vehicle is running, and the axle steer that tries to rotate the front axle 5 One end is pivotally mounted in the vicinity of the attachment portion of the lower rod 7 to the chassis frame 3 and the other end is pivotally mounted on the front axle 5 and arranged in the front-rear direction.
[0019]
Further, as shown in FIG. 3, the torque rod 11 is provided only on the side opposite to the one side where the steering link mechanism is connected to the front axle 5. That is, in FIG. 3, on one side (the left side of the vehicle) of the front axle 5 opposite to the side (the right side of the vehicle) on which the steering arm 18 fixed to the left knuckle 12 is viewed from the front. A torque rod 11 is provided.
[0020]
As shown in FIG. 1, the front end of the torque rod 11 is pivotally attached to a common bracket obtained by increasing the size of the bracket 15 pivotally attached to the front end of the lower rod 7 through a rubber bush. Yes. Further, as shown in FIG. 2, the rear end of the front axle 5 is pivotally attached to a bracket 19 formed in a hanging shape at one side portion 5 'by a bolt via a rubber bush. In this state, the front end of the torque rod 11 is, for example, a bracket 15 that pivotally attaches to the front end of the left lower rod 7, and the rotational center of both is matched, and the front axle 5, the left lower rod 7, and the torque rod 11 are triangular. The link structure is formed.
[0021]
As described above, only one torque rod 11 is provided on the side opposite to one side where the steering link mechanism is connected to the front axle 5 because the drag link is connected to the steering arm 18 shown in FIG. 9 (see FIG. 7B) is considered to exert an action against the axle steer in the other side portion of the front axle 5 in the same manner as the torque rod 11, so that it is provided on the opposite side without such a structure. It is because it is good.
[0022]
Next, FIG. 7 and FIG. 8 show the simulation results for the generation of axle steer in a vehicle equipped with the front suspension device of the present invention to which the torque rod 11 is added. FIG. 7B shows the front suspension apparatus of the present invention as a simulation model. That is, two left and right upper rods 6, 6, two lower rods 7, 7 whose other ends are pivotally attached to a substantially central portion of the front axle 5 and arranged in a V shape, and a left rod 7 in the vicinity. The model Mb provided with the added torque rod 11 is shown.
[0023]
FIG. 8 is a graph showing a simulation result when the external force F at the time of climbing one wheel step is input to one of the front wheels 8 for the model Mb, together with the simulation result of the model Ma of the conventional front suspension device described above. Show. When the front suspension apparatus of the present invention is a model Mb, as shown by an elliptical area in the center of FIG. 8, the amount of deviation of the front axle 5 in the X direction and the angle difference are smaller than the model Ma of the conventional apparatus. It has become. Therefore, it can be seen that the generation of axle steer is further suppressed and the running stability of the entire vehicle is improved.
[0024]
1, 3, and 7 (b) show the case where the torque rod 11 is provided only on the side opposite to one side where the steering link mechanism is connected to the front axle 5. However, the present invention is not limited to this, and one may be provided only on one side portion to which the steering link mechanism is coupled. In this case, when an external force F acts on the front wheel 8 on the side opposite to the one side where the steering link mechanism is connected to the front axle 5, the action of the torque rod 11 against the axle steer decreases. However, generation of axle steer can be suppressed as compared with a conventional front suspension device.
[0025]
FIG. 4 is a schematic plan view showing another embodiment of the front suspension apparatus according to the present invention. In this embodiment, one torque rod 11 is provided on each side of the front axle 5 where the steering link mechanism is connected and on the opposite side. That is, a total of two torque rods 11 are provided symmetrically on both sides of the front axle 5. In this case, the action against the axle steer by the torque rods 11 on both sides is increased, and the occurrence of axle steer at the time of external force input to the front wheel 8 during traveling, etc. is sufficiently suppressed to further improve traveling stability. Can do.
[0026]
【The invention's effect】
Since the present invention is configured as described above, according to the first aspect of the present invention, one end is pivotally attached to the chassis frame, and the other end is pivotally attached to a substantially central portion of the front axle, and is arranged in a V shape. the two bets Rukuroddo arranged in the longitudinal direction at the mounting plane and the same plane of Rowaroddo that is, by providing one only on the opposite side whereas the front axle and one side of the steering linkage is connected With this torque rod , for example, when one wheel rides on something while traveling and external force is input from the front, it receives the force at the input part and counters the axle steer that tries to rotate the front axle Can do. In addition, by providing only one torque rod that opposes this axle steer only on the side opposite to the one side to which the steering link mechanism is connected, it effectively resists axle steer and simplifies the structure and reduces costs. Reduction can be achieved .
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing an embodiment of a front suspension apparatus for a low floor bus according to the present invention.
FIG. 2 is a left side view of FIG.
FIG. 3 is a schematic front view showing a front suspension device for the low floor bus.
FIG. 4 is a schematic plan view showing another embodiment of the front suspension device for the low floor bus.
FIG. 5 is a schematic plan view showing a conventional front suspension device for a low floor bus.
6 is a left side view of FIG. 5. FIG.
FIG. 7 is an explanatory diagram showing a model for simulating generation of axle steer in a vehicle equipped with a conventional and the front suspension device of the present invention.
FIG. 8 is a graph showing a simulation result when an external force at the time of riding on one wheel step is input to one front wheel for the above model.
[Explanation of symbols]
3 ... Chassis frame 4 ... Air spring 5 ... Front axle 6 ... Upper rod 7 ... Lower rod 9 ... Drag link 11 ... Torque rods 14, 15, 16, 19 ... Bracket

Claims (1)

A front axle disposed below the chassis frame and suspended by an air spring;
Two left and right upper rods having one end pivotally attached to the chassis frame and the other end pivotally attached to both sides of the front axle,
Two lower rods having one end pivotally attached to the chassis frame and the other end pivotally attached to a substantially central portion of the front axle and arranged in a V-shape;
In the low-floor bus front suspension device with
In the same plane as the mounting plane of the two lower rods, one end is pivotally mounted in the vicinity of the mounting portion of the lower rod to the chassis frame and the other end is pivotally mounted on the front axle and arranged in the front-rear direction . A front suspension apparatus for a low floor bus, wherein a single rod is provided only on the side opposite to one side where the steering link mechanism is connected to the front axle .

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