JP4512288B2 - Vehicle with axle lift mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle having a plurality of rear wheels composed of driving wheels and driven wheels, and more particularly to a vehicle with an axle lift mechanism that can secure a sufficient driving force when empty and lightly loaded. .
[0002]
[Prior art]
In a large vehicle such as a truck, as shown in FIG. 8, a plurality (two in the figure) including a drive wheel 50 disposed in front of the vehicle 53 and a driven wheel 51 disposed at a distance behind the drive wheel 50. A type having rear wheels 52 is known.
[0003]
By the way, in recent years, due to the relaxation of laws and regulations, the maximum vehicle weight limit of 20t has been allowed up to 25t. As a result, until now, the shaft weight of the drive shaft that supports the drive wheel 50 is approximately 10 t and the shaft weight of the driven shaft that supports the driven wheel 51 is approximately 5 t. The axial weight of the driven shaft became approximately 10 t (the axial weight of one axis was determined up to 10 t). That is, the ratio of the axial weight of the drive shaft to the driven shaft was approximately 2: 1, and the ratio was approximately 1: 1.
[0004]
For this reason, especially when the vehicle is empty or lightly loaded, the shaft weight of the drive shaft is reduced, that is, the ground pressure of the drive wheel 50 is reduced, and a sufficient drive force cannot be ensured when starting or climbing. was there.
[0005]
Therefore, as a countermeasure against this, an empty vehicle start-up drive auxiliary device as disclosed in Japanese Patent Laid-Open No. 8-156562 has been proposed. In this apparatus, the driven shaft is lifted when there is no load, and the driving force is ensured by forcibly increasing the axial weight of the driving shaft.
[0006]
[Problems to be solved by the invention]
However, if the driven wheel 51 arranged on the rear side of the vehicle is completely lifted from the ground, as shown in FIG. 8, the rear overhang L (from the center of the wheel located at the rearmost part among the grounded wheels). The distance to the rear end of the vehicle changes to L ′ and exceeds the reference, and the departure angle θ (the tangent plane of the wheel located at the rearmost of the grounded wheels and the rear end of the vehicle) The angle between the line connecting the two and the longitudinal axis of the vehicle changes to θ ′, and the running performance is degraded. For this reason, the driven wheel 51 could not be lifted completely.
[0007]
Therefore, conventionally, the driven wheel 51 is lifted to the extent that it does not float completely, thereby changing the axial load distribution of the drive shaft 50 and the driven shaft 51 to ensure the driving force.
[0008]
However, traveling without completely lifting the driven wheel 51 not only reduces the driving force improvement effect, but also causes the wearer wheel 51 to wear because the driven wheel 51 with a low ground pressure slides sideways when the vehicle turns. This has led to intensification of fuel consumption and deterioration of fuel consumption, leading to an increase in costs during vehicle operation.
[0009]
Accordingly, an object of the present invention is to solve the above-mentioned problems, and can completely lift the driven wheel without changing the rear overhang and the departure angle, and can secure a sufficient driving force when empty and lightly loaded. The object is to provide a vehicle with a lift mechanism.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to a vehicle having a plurality of rear wheels including drive wheels and driven wheels arranged at intervals in the longitudinal direction of the vehicle. A drive shaft that supports the drive wheel by providing a lift mechanism that lifts the drive wheel so that only the drive wheel is grounded when the loaded weight is equal to or less than a predetermined weight on the driven shaft that is disposed at the end and supports the driven wheel. However, in order to form a differential gear box, it has an upper housing whose central portion is curved upward and a lower housing whose central portion is curved downward, and the driven shaft transmits driving force from the engine to the driving wheels. An upper member having the same shape as the upper housing so as to have a curved relief portion that is curved so as not to interfere with the propeller shaft, and has a shape that follows the upper member, and the upper portion Is that formed by the lower member to be joined to the bottom.
[0011]
According to this, since the driving wheel is disposed at the rearmost part of the vehicle, the rear overhang and the departure angle do not change even if the driven wheel is completely lifted from the ground. Accordingly, a sufficient driving force can be ensured at the time of empty loading and light loading, and the driving cost can be reduced without causing excessive wear of the driven wheel and deterioration of fuel consumption due to the side slip of the driven wheel. Further, since the upper housing of the drive shaft can be used jointly as the upper member of the driven shaft, a new press die dedicated to the upper member is not necessary, and the manufacturing cost can be reduced.
[0014]
According to a second aspect of the present invention, there is provided a vehicle having a plurality of rear wheels including drive wheels and driven wheels arranged at intervals in the longitudinal direction of the vehicle, wherein the drive wheels are arranged at the rearmost part of the vehicle. The driven shaft that supports the driven wheel is provided with a lift mechanism that lifts the driven wheel so that only the driven wheel is grounded when a loaded weight is equal to or less than a predetermined weight, and the drive shaft that supports the driven wheel is a differential gear box. In order to form the upper housing, the upper housing is curved upward and the lower housing is curved downward. The driven shaft has the same shape as the upper member and the lower housing. The propeller shaft, which is composed of a lower member of the shape and transmits the driving force from the engine to the driving wheel, passes through the insertion space formed in the central portion of the upper member and the lower member. It is intended to be arranged to. According to this, since the upper housing of the drive shaft can be used jointly as the upper member of the driven shaft and the lower housing can be used jointly as the lower member, a new press die dedicated to the driven shaft is not required, and the manufacturing cost can be reduced.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0016]
FIG. 1 is a perspective view showing a lift mechanism of a vehicle with an axle lift mechanism according to an embodiment of the present invention, FIG. 2 is a schematic side view showing the lift mechanism, and FIG. 3 shows a driven wheel and a drive wheel grounded. FIG. 4 is a side view showing a state where the driven wheel is lifted from the ground and only the driving wheel is grounded.
[0017]
The present invention is applied to a large vehicle such as a truck. As shown in FIGS. 3 and 4, a plurality of driving wheels 10 and driven wheels 11 (which are arranged at intervals in the longitudinal direction of the vehicle). The illustrated embodiment has two rear wheels 12.
[0018]
The driving wheel 10 is supported by a driving shaft 13 shown in FIG. 1, and a driving force from an engine mounted on the vehicle front F side is formed in a differential gear box formed at the center of the propeller shaft 16 and the driving shaft 13. 17 is transmitted to the drive wheel 10 through a differential gear accommodated in the motor 17.
[0019]
The driven wheel 11 is supported by a driven shaft 15 via a bearing (not shown) and rotates relative to the driven shaft 15. The driven shaft 15 is for supporting the driven wheel 11 and does not rotate.
[0020]
An air suspension 21 is provided on the drive shaft 13 and the driven shaft 15. The air suspension 21 includes an arm 19 that is connected to the lower side of the drive shaft 13 and the driven shaft 15 and extends in the longitudinal direction of the vehicle, and air springs 20 provided at both ends of the arm 19. The lower part of the air spring 20 is fixed to the upper surface of the arm 19, and the upper part is attached to the side member 22 of the vehicle frame so that the impact of the drive shaft 13 and the driven shaft 15 can be absorbed and reduced.
[0021]
As is apparent from the figure, the gist of the present invention is that the driving wheel 10 and the driving shaft 13 are arranged at the rearmost part of the vehicle, and the driven wheel 11 and the driven shaft 15 are arranged on the front F side. Thereby, even if the driven wheel 11 is completely lifted from the ground, the rear overhang and the departure angle do not change.
[0022]
The driven shaft 15 is provided with a lift mechanism 23 for lifting the driven wheel 11 completely from the ground and grounding only the driving wheel 10 in order to secure a driving force when the loaded weight is equal to or less than a predetermined weight. . Lift mechanism 23 is of the same air spring and air spring 20 of the air suspension 21 is fixed to the bracket 25 to which the lower part is attached to the side member 22, 22 of both sides of the vehicle body, the upper bracket to the driven shaft 15 2 8 is fixed. Accordingly, by removing air from the air spring 20 of the air suspension 21 provided on the driven shaft 15 and supplying air to the air spring 23 constituting the lift mechanism, the driven shaft 15 and the driven wheel 11 supported thereby are driven. Lifted up. The lift mechanism 23 has a stroke so that the driven shaft 15 can be lifted until the driven wheel 11 is completely lifted from the ground.
[0023]
By the way, when the drive shaft 13 is arranged at the rearmost part of the vehicle and the driven shaft 15 is arranged in front of the vehicle, the propeller shaft 16 that transmits the driving force from the engine to the drive wheels 10 interferes with the driven shaft 15. (Usually the driven shaft is linear). It is conceivable that the propeller shaft 16 is divided into a plurality of parts and bent so as to avoid the driven shaft 15 and connected by a universal joint. In this case, the intersection angle of the propeller shaft 16 increases, and the driving torque and rotational speed are increased. Fluctuates and causes vibration of the vehicle and abnormal wear of the reduction gear and wheels.
[0024]
Therefore, in the present embodiment, the driven shaft 15 is curved so as not to interfere with the propeller shaft 16. That is, as shown in FIG. 5, the driven shaft 15 has an upper member 26 whose center portion is curved upward, and a lower member 27 having a shape following the upper member 26 and welded to the lower portion of the upper member 26. A curved relief portion 29 is formed at the central portion. The propeller shaft 16 passes through the inside of the curved relief portion 29. By making the driven shaft 15 curved in this way, the intersection angle of the propeller shaft 16 can be reduced (within about 5 °) as in the prior art, so that vibration of the vehicle and abnormal wear of the reduction gear and wheels can be prevented. .
[0025]
However, making the driven shaft 15 different from the conventional shape requires a press die for forming the new driven shaft 15. This is a cost loss because the press mold is very expensive. Therefore, in this embodiment, a part of the driven shaft 15 is a common component having the same shape as one component of the drive shaft 13.
[0026]
That is, as shown in FIG. 6, the drive shaft 13 includes an upper housing 30 whose central portion is curved upward, a lower housing 31 whose central portion is curved downward, and an upper housing 30 to form a differential gear box 17. The upper member 26 of the driven shaft 15 has the same shape as the upper housing 30 of the drive shaft 13. In this case, since only the lower member 27 of the driven shaft 15 becomes a member having a new shape, one type of new press die may be used, and the cost can be reduced. Note that a strength member 32 may be provided at the joint between the upper member 26 and the lower member 27 of the driven shaft 15.
[0027]
A modification of the driven shaft 15 is shown in FIG. In this embodiment, the upper member 26 ′ of the driven shaft 15 has the same shape as the upper housing 30 of the drive shaft 13, and the lower member 27 ′ is a common member having the same shape as the lower housing 31. That is, the driven shaft 15 is formed of an upper member 26 ′ whose center portion is curved upward and a lower member 27 ′ whose center portion is curved downward, and the center portion of these upper member 26 ′ and lower member 27 ′. The propeller shaft 16 is allowed to pass through the insertion space 33 formed in the above. In this way, a new press die is not required, which is very effective for cost reduction.
[0028]
Further, if the driven shaft 15 and the drive shaft 13 are used as a common member in this manner, brackets attached to the driven shaft 15 and the drive shaft 13 are conventionally required for exclusive use, but can be shared. There is also a merit. In addition, the ability to share parts leads to a reduction in parts management costs.
[0029]
Returning to FIG. 1, in the present embodiment, the propeller shaft 16 is connected to an extension 35 that compensates for the length of the drive wheel 10 disposed at the rearmost part of the vehicle by a universal joint 36. The connecting portion is supported by a support bracket 36 attached to the driven shaft 15. Further, the propeller shaft 16 is provided with a serration portion 37 for adjusting the length of the propeller shaft 16 when the driven shaft 15 is raised or lowered.
[0030]
Next, the operation of this embodiment will be described.
[0031]
First, when the loading weight of the vehicle is equal to or greater than a predetermined weight, the shaft weight of the drive shaft 13 is large even when both the driving wheel 10 and the driven wheel 11 are grounded, and a sufficient driving force can be secured. As shown, the air of the lift mechanism 23 is extracted and contracted. At this time, the drive wheel 10 and the driven wheel 11 are in contact with the ground A.
[0032]
Next, when the loaded weight becomes equal to or less than the predetermined weight, the air spring 20 of the air suspension 21 provided on the driven shaft 15 is removed and the lift mechanism 23 is supplied with air. As a result, as shown in FIG. 4, the air spring 20 contracts and the lift mechanism 23 swells to lift the driven shaft 15 upward. As a result, the driven wheel 11 is completely lifted from the ground A, and only the driving wheel 10 is grounded.
[0033]
As a result, since all the loads on the rear axle are supported by the drive shaft 13, the axle weight of the drive shaft 13 increases, and a sufficient driving force can be ensured even when starting or climbing.
[0034]
Further, since the driven wheel 11 is completely lifted from the ground A, a side slip does not occur when turning, and there are no problems such as wear of the driven wheel 11 and deterioration of fuel consumption.
[0035]
Further, since the drive shaft 13 is disposed at the rearmost part of the vehicle, the rear overhang and the departure angle do not change even when the driven wheel 11 is completely lifted.
[0036]
So far, the air spring has been described as being used as the lift mechanism 23, but the present invention is not limited in this respect, and other configurations such as an air cylinder, a hydraulic cylinder, and an electric actuator may be used.
[0037]
Further, although the air suspension vehicle has been described, the present invention can also be applied to a trunnion suspension vehicle using a leaf spring. In this case, instead of lifting the driven shaft, the drive shaft may be pushed downward to lift the driven wheel from the ground.
[0038]
The vehicle may be provided with detection means for notifying the driver and the worker when the loaded weight of the vehicle becomes a predetermined weight or less. Alternatively, the driven wheel may be automatically lifted when it is detected by the detecting means that the loaded weight is equal to or less than a predetermined weight.
[0039]
【The invention's effect】
In short, according to the present invention, the following excellent effects are exhibited.
1) A sufficient driving force can be ensured when empty and lightly loaded.
2) The driven wheel does not skid.
3) Rear overhang and departure angle do not change.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a lift mechanism of a vehicle with an axle lift mechanism according to an embodiment of the present invention.
FIG. 2 is a schematic side view of a lift mechanism.
FIG. 3 is a side view showing a state in which a driven wheel and a driving wheel are grounded.
FIG. 4 is a side view showing a state in which only a driving wheel is grounded by lifting a driven wheel from the ground.
FIG. 5 is a front view of a driven shaft.
FIG. 6 is a front view of a drive shaft.
FIG. 7 is a front view showing a modified example of the driven shaft.
FIG. 8 is a schematic side view of a large vehicle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Drive wheel 11 Drive wheel 12 Rear wheel 13 Drive shaft 15 Drive shaft 16 Propeller shaft 23 Lift mechanism 26 Upper member 27 Lower member 30 Upper housing 31 Lower housing

Claims (2)

In a vehicle having a plurality of rear wheels composed of drive wheels and driven wheels arranged at intervals in the longitudinal direction of the vehicle, the drive wheels are arranged at the rearmost portion of the vehicle and are used as driven shafts that support the driven wheels. A lift mechanism is provided for lifting the driven wheel so that only the driving wheel is grounded when the loaded weight is equal to or less than a predetermined weight, and the driving shaft supporting the driving wheel has a central portion upward to form a differential gear box. It has a curved upper housing and a lower housing whose center is curved downward, and the driven shaft has a curved relief portion curved so as not to interfere with a propeller shaft that transmits driving force from the engine to the driving wheel. said a upper housing and the upper member of the same shape, a shape following the upper side member, and that is formed by the lower member to be joined to the lower portion of the upper member as Axle lift mechanism with the vehicle, characterized. In a vehicle having a plurality of rear wheels composed of drive wheels and driven wheels arranged at intervals in the longitudinal direction of the vehicle, the drive wheels are arranged at the rearmost part of the vehicle and are used as driven shafts that support the driven wheels. A lift mechanism is provided to lift the driven wheel so that only the driving wheel is grounded when the loaded weight is equal to or less than a predetermined weight, and the driving shaft that supports the driving wheel has a central portion upward to form a differential gear box. An upper housing having a curved shape and a lower housing having a central portion curved downward; and the driven shaft is composed of an upper member having the same shape as the upper housing and a lower member having the same shape as the lower housing. The propeller shaft for transmitting the driving force from the driving wheel to the driving wheel is disposed so as to pass through the insertion space formed in the central part of the upper member and the lower member. Axle lift mechanism with a vehicle to be butterflies.

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