JPH0885317A - Pneumatic suspension device - Google Patents

Abstract

PURPOSE: To restrain the longitudinal inclination of a suspension beam when a vehicle is accelerated or decelerated. CONSTITUTION: Air springs 13, 15 are severally interposingly supported between each end of a pair of a front and a rear lateral member 3, 12 joined to a car frame 2 and the front and rear ends of an arched suspension beam 10 to support each end of an axle case 8. A pair of right and left longitudinal torque rods 5 is connected between the central upper part of the axle case 8 and the car frame 2. A pair of right and left longitudinally oblique radius rods 6 is connected between each suspension beam 10 and the lower part of a front lateral member 3. The axle case 8 is supported on the suspension beam 10 by a bearing so as to be rotatable round a central axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an air spring type suspension device for rear wheels which is attached to a large vehicle, and more particularly to an air spring type suspension device for suppressing the left and right suspension beams from tilting forward and backward when the vehicle is accelerated or decelerated. It relates to suspension devices.

[0002]

2. Description of the Related Art In a leaf spring type suspension device for rear wheels, when a driving torque is transmitted from a differential device to a rear axle during acceleration of a vehicle, the axle case receives a torque reaction force to cause waving of the leaf spring. Let During deceleration of the vehicle, the torque reaction force applied to the axle case is in the opposite direction, causing the leaf spring to waving in the opposite direction.

In an air spring type suspension system for rear wheels of a large-sized vehicle carrying a heavy load, four air springs are used because the supporting load of the rear wheels is large. That is, the rear wheel axle case is supported by a pair of left and right suspension beams, and the front and rear ends of each suspension beam are supported by the vehicle frame by air springs. In particular, by adopting a plane bow-shaped suspension beam, the mounting position of the air spring can be arranged at a position distant from the center of the vehicle body to the outer side, so that the roll rigidity of the vehicle body is increased and the vehicle can be easily rotated when turning. The roll amount of the vehicle body can be reduced. The front and rear movement of the axle case is controlled by a torque rod, and the left and right movement of the axle case is controlled by a radius rod.

However, the above-mentioned so-called wide type air spring type suspension device has the following problems with respect to the pitch motion of the vehicle body during acceleration and deceleration of the vehicle. In other words, the torque reaction force acting on the axle case during acceleration / deceleration of the vehicle is supported by the torque rod and the radius rod, but if the torque rod and the radius rod are arranged horizontally, the inertia force acting on the center of gravity of the vehicle and the center of the axle case Due to the difference in moment from the acceleration / deceleration force that acts, the rear part of the vehicle body sinks when the vehicle accelerates, and the rear part of the vehicle body floats when braking.

At this time, ignoring the deformation of the elastic bushes and the like at the mounting portions of the torque rod and the radius rod, the axle case is restrained by the upper radius rod and the lower torque rod, and is linear in the vertical direction with respect to the vehicle body. Therefore, the suspension beam that fixedly supports the axle case cannot maintain the horizontal posture. The inclination of the suspension beam in the front-rear direction gives a larger displacement to the air spring as the suspension beam becomes longer, and the suspension beam becomes heavier as the suspension beam becomes longer, resulting in a large inertial force of the suspension beam when the axle case is rotationally displaced. Become.

Therefore, in the wide type air spring type suspension device, the geometrical arrangement of the link mechanism is adopted so as to suppress the sinking of the rear portion of the vehicle body and the lifting of the rear portion of the vehicle body during acceleration / deceleration, and the mounting portions of the torque rod and the radius rod are adopted. The impact load is moderated by the elastic bush. However, although the upper radius rod directly regulates the axle case, the lower torque rod regulates the suspension beam, and the rigidity (elastic bush) of the link mechanism against external force in the front-back direction is large, but Since the rigidity (air spring) of the link mechanism with respect to the external force in the direction is small, the bounce (vertical movement) of the axle case cannot be sufficiently regulated even if the geometrical arrangement of the link mechanism is adopted. For this reason, the suspension beam tilts when the vehicle is accelerated / decelerated, and when the suspension beam tilts in the front-rear direction, the torque rod and the radius rod are displaced from each other, so that the force acting on the torque rod becomes large and the force acting on the air spring becomes large. The posture of the car body changes significantly.

In summary, the conventional air spring type suspension system has the following problems.

(A) During acceleration / deceleration of the vehicle, a torsional force acts on the left and right suspension beams with a change in the driving torque of the rear wheels, and a large forward / backward force acts on the torque rod and the radius rod.

(B) Twisting of the suspension beam easily causes the rear portion of the vehicle body to sink and the rear portion of the vehicle body to rise.

(C) When the vehicle is accelerated or decelerated, the torsional force acting on the suspension beam and the longitudinal force acting on the torque rod and the radius rod increase the load on the elastic bushes of the mounting portions of the torque rod and the radius rod, and the performance of the harness deteriorates. To do.

[0011]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an air spring type suspension device which prevents the suspension beam from tilting in the front-rear direction when the vehicle is accelerated or decelerated. is there.

[0012]

In order to achieve the above-mentioned object, the structure of the present invention has a front and rear end of a suspension beam which supports each end of a pair of front and rear lateral members connected to a vehicle frame and each end of an axle case. And an air spring type suspension device in which air springs are respectively interposed between the axle case and the suspension case so as to be rotatable about the central axis with respect to the suspension beam.

[0013]

According to the present invention, both ends of the axle case are rotatably supported by the left and right suspension beams. When the vehicle is accelerated or decelerated, the driving torque acting on the axle changes, whereas the torque reaction acts on the axle case. At this time, only the axle case rotates and the torque reaction force is not transmitted to the left and right suspension beams. Rotation of the axle case is suppressed by the vehicle frame via the torque rod and radius rod. Since the suspension beam does not receive the torque reaction force, the suspension beam does not tilt in the front-rear direction, and therefore the vertical movement of the rear axle is suppressed, and a stable body posture can be obtained.

[0014]

1 is a plan view of an air spring suspension system according to the present invention, and FIG. 2 is a left side sectional view of the same. As shown in FIGS. 1 and 2, an air spring suspension system applied to a large-sized bus in which an engine is mounted at the rear of a vehicle body includes a pair of left and right vehicle frames 2 extending in the front-rear direction and a pair of front and rear lateral members 3, 3. 12 combined, car frame 2
The upper ends of the air springs 13 and 15 are connected to the lower surfaces of the end portions of the lateral members 3 and 12 that project outward from the axle case 8
A pair of left and right suspension beams 10 having a planar bow shape are connected to both ends of the suspension beam 10 by bolts, and lower ends of air springs 13 and 15 are connected to upper surfaces of front and rear ends of each suspension beam 10.

In order to suppress the longitudinal movement and the lateral movement of the axle case 8, the left and right 1 which protrude downward from each end of the lateral member 3
Torque rods 5 in the front-rear direction are respectively connected between the pair of leg pieces 4 and the inner wall of each suspension beam 10, and the axle case 8
A pair of radius rods 6 extending forward and obliquely laterally from the central portion of the vehicle, that is, the upper wall of the final reduction gear 7 toward the vehicle frame 2 are connected. The propulsion shaft 7a protruding rearward from the final reduction gear 7 is
It is connected to the crankshaft of the engine via a transmission mounted on the rear of the vehicle body.

According to the present invention, as shown in FIG. 3, the end of the axle case 8 is rotatably supported with respect to the suspension beam 10. That is, as shown in FIG. 4, the axle case 8 having a cylindrical cross section is integrally formed with a thick wall portion 8a projecting radially outward at an intersection with the suspension beam 10 and the thick wall portion 8a.
Is rotatably sandwiched by a pair of upper and lower holders 32, 33 via a slide bearing 40, and is placed on a seat plate 34 which is placed on the upper surface of the suspension beam 10, and a seat plate 36 is mounted on the lower surface of the suspension beam 10. Apply 4 bolts 35 to the front and rear
6, the sleeve 41, the holders 33 and 32 are penetrated, and the nut 31 is fastened. In FIG. 4, a pair of front and rear bolts 35 on the left side are arranged along the left side wall of the suspension beam 10, and a pair of front and rear bolts 35 on the right side are arranged to penetrate the suspension beam 10.

As shown in FIG. 4, the holders 32 and 33 are provided on the inner surface of the semi-cylindrical portion in the left-right direction (axial direction) of the axle case 8.
In order to prevent the movement of the thick wall portion 8a, circumferential protrusions 32a and 33a that hold both ends of the thick portion 8a are formed. Plain bearing 4
A roller bearing or the like may be used instead of zero.

According to the present invention, since the axle case 8 is rotatably supported by the suspension beam 10, only the axle case 8 rotates with respect to the torque reaction force acting on the axle case 8 during acceleration and deceleration of the vehicle. The torque reaction force is not transmitted to the suspension beam 10. A simple longitudinal force acts on the link mechanism including the torque rod 5 and the radius rod 6, and the rotation of the axle case 8 is suppressed by the torque rod 5 and the radius rod 8.

[0019]

As described above, according to the present invention, since the axle case is rotatably supported with respect to the suspension beam, the torque reaction force acting on the axle case during acceleration / deceleration of the vehicle is not transmitted to the suspension beam, so that the torque rod can be operated. A simple front-back force is applied to the link mechanism including the and the radius slot, and the front-back force is supported by the vehicle frame via the torque rod and the radius rod.

Excessive external force due to swinging of the suspension beam (inclination in the front-rear direction) is eliminated, so that the load on the elastic bushes of the mounting portions of the torque rod and the radius rod is reduced, and excessive movement of the air spring type suspension device is suppressed. Therefore, the harshness performance is improved.

[Brief description of drawings]

FIG. 1 is a plan view of an air spring suspension system according to the present invention.

FIG. 2 is a left side sectional view of the same air spring type suspension device.

FIG. 3 is a side sectional view showing an enlarged main part of the air spring suspension system.

4 is a rear cross-sectional view of the main part taken along the line 4A-4A in FIG.

[Explanation of symbols]

2: Vehicle frame 3, 12: Lateral member 5: Torque rod 6:
Radius rod 7: Final reducer 8: Axle case 8
a: Thick part 10: Suspended beam 13, 15: Air spring 14: Rear wheel 31: Nut 32, 33: Holder 3
2a, 33a: ridges 34, 36: seat plate 35: bolt
40: Bearing

Claims (2)

[Claims] 1. An air spring type suspension in which air springs are respectively interposed and supported between each end of a pair of front and rear lateral members connected to a vehicle frame and the front and rear ends of a suspension beam supporting each end of an axle case. In the device, an air spring type suspension device, wherein an axle case is supported so as to be rotatable around a central axis with respect to a suspension beam. 2. A pair of left and right radius rods in the front-rear diagonal direction are connected between the upper center part of the axle case and the vehicle frame,
The air spring suspension system according to claim 1, wherein a pair of left and right torque rods in the front-rear direction are connected between each suspension beam and the lower portion of the front transverse member.