JPH07309115A - Rear suspension used for commercial vehicle - Google Patents

Abstract

PURPOSE:To improve the comfortableness and the steering stability by supporting a rear axle on a frame through an upper and lower torque rods and an air spring so as to realize the respectively prescribed relative position to lower the frame. CONSTITUTION:The lower side of a rear axle 43 is connected to a frame 41 by a lower torque rod 12 so as to set the axle housing center Ob at the position higher than the axle height forward of the rear axle 43 arranged forward of an air spring 11. The upper side of the rear axle 43 is connected to the frame 41 through an upper torque rod 13 at the position to set the axle compliance center Oc rearward of the rear axle 43. The lateral rigidity of the axle compliance center Oc is set to be larger than that of the axle housing center Ob. Thus, the shocks in the longitudinal direction and in the lateral direction received by the bound and rebound can be reduced, the comfortableness, the startability from, and the steering stability can be improved, and the weight can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear suspension used in a commercial vehicle, and more particularly to a rear suspension suitable for medium and small buses where a wheel base is short.

[0002]

[Background Art] In this kind of small and medium-sized buses, a rear suspension that combines an air spring with a leaf spring is generally used, and there,
Since the leaf springs are used in the forward ascent, it is difficult to improve the steering stability and riding comfort by raising the frame.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rear suspension used in a commercial vehicle in which a frame can be lowered to improve riding comfort and steering stability.

[0004]

[Means corresponding to the problem and its action]
Left and right air springs are located behind the rear axle to support the rear axle on the frame, and left and right lower torque rods are located in front of the rear axle and above the axle height. -Connect the underside of its rear axle to its frame in an arrangement that sets the bouncing center, and the left and right upper torque rods in that arrangement that sets the axle compliance center behind the rear axle. Connect the upper side of the rear axle to the frame, and omit the leaf springs to lower the frame to control axle bouncing and pitching, and external forces, lateral and longitudinal forces When acting on a part, it creates compliance understeer on the axle. It is.

Further, according to the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque rods are connected to the front suspension and the rear suspension. The lower side of the rear axle is connected to the frame in an arrangement that sets at least the axle bouncing center near the conjugate point of the suspension, and left and right upper torque rods are attached to the rear of the rear axle.・
Connect the upper side of its rear axle to its frame in an arrangement that sets the compliance center, and reef
The springs are omitted to lower the frame, restrain the bouncing and pitching of the axle, and when an external force, i.e. lateral force or longitudinal force, acts on the tire's ground contact, the axle will be under compliance
It is about to cause steer.

Further, according to the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque rods are provided in front of the rear axle. The lower part of the rear axle is connected to the frame in a position where the axle bouncing center is set at a position higher than the axle height, and the left and right upper torque rods are located behind the rear axle and center for the axle compliance. Connect the upper side of the rear axle to the frame with the setting to set,
Then, the lateral rigidity of the axle compliance center is set to be larger than that of the axle bouncing center, and the leaf spring is omitted to lower the frame, suppressing the bouncing and pitching of the axle, and When an external force, that is, a lateral force or a longitudinal force, acts on the ground contact portion of the tire, it is a place where compliance understeer is agilely generated on the axle.

Furthermore, according to the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque rods are connected to the front suspension and the rear suspension. Connect the lower side of the rear axle to the frame with an arrangement that sets at least the axle bouncing center near the conjugate point of the suspension, and
A rod connects the upper side of the rear axle to the frame in an arrangement that sets the axle compliance center behind the rear axle, and the lateral stiffness of the axle compliance center is that of the axle bouncing center. Set larger than that, and
Omit the leaf spring to lower the frame,
It suppresses the bouncing and pitching of the axle, and when an external force such as lateral force or longitudinal force acts on the ground contact part of the tire, compliance with the axle
It's about agile causing Anda Steer.

[0008]

DESCRIPTION OF SPECIFIC EXAMPLES Specific examples of the tandem axle trunnion type rear suspension of the present invention will be described below with reference to the drawings. 1 to 5
Shows a specific example 10 of the rear suspension used in the commercial vehicle of the present invention applied to the medium-sized bus 40. This rear suspension 10 is the medium-sized bus 4
0, left and right air springs 11 and 11 arranged behind the rear axle 43 to support the rear axle 43 on the frame 41, and the rear axle 4 thereof.
The left and right lower torque rods that connect the lower side of the rear axle 43 to the frame 41 in an arrangement in which the axle bouncing center O _b is set at a position (L _f , h) higher than the axle height in front of 3. 12, 12 and the rear of the rear axle 43, the axle compliance center O
The rear axle 43 is assembled with the left and right upper torque rods 13, 13 connecting the upper side of the rear axle 43 to the frame 41 in a setting for setting _c , and in the rear suspension 10, the axle compliance center O The lateral stiffness of _c is set larger than that of its axle bouncing center O _b .

Further, in the medium-sized bus 40 to which the rear suspension 10 is applied, the rear axle 4 is
3 is assembled by the left and right drive shafts and an axle housing supporting the left and right drive shafts, and its frame 41
Are arranged laterally with respect to the left and right side rails 42, 42 of which two rear wheels 44,
44 is normally supported. Also, its left and right drive shafts are normally coupled to a differential mounted in a differential carrier (not shown).

More specifically, the rear suspension 10 will firstly include the left and right air springs 1.
1, 11, the rear axle 43 is the frame 41
Of the left and right air spring seats 14, 14 for corresponding support on the left and right side rails 42, 42 of the
Is located below the rear axle 43, and
Axle pads 15 and 15 arranged on the upper side of the rear axle 43 with U-shaped bolts 27 and 27 and their rear
The rear axle 43 is tightened together with the axle 43
The left and right air spring brackets 16, 16 are adapted to the left and right side rails 42, 42 so as to face the rear ends of the left and right air spring seats 14, 14, respectively. Screwed to. The left and right air springs 11, 11 are disposed correspondingly between the rear ends of the left and right air spring seats 14, 14 and the left and right air spring brackets 16, 16. It is fixedly screwed to.

Left and right air springs 11, 11
Is connected to an air tank by a pipe, and compressed air is supplied and discharged by a leveling valve arranged in the middle of the pipe. Of course, the leveling valve has its built-in piston moved by a lever to close the exhaust port and connect the tank port to the bellows port, and also close the tank port to connect the bellows port to the exhaust port. And is attached to one of the left and right side rails 42, 42 of the frame 41 so that the lever is linked to the rear axle 43 via a linkage.

The left and right lower torque rods 12, 1
2 is a front constriction where the axle bouncing center O _b is set in front of the rear axle 43 and at a position (L _f , h) higher than the axle height, and is arranged in the front upward direction. That is, the left and right lower torque rods 1
2, 12 are imaginary axis lines 20 that extend forward on the axis lines,
Left and right front hangers 20 are arranged at an incline through its axle bouncing center O _b and the front end is correspondingly screwed in front of its rear axle 43 to its left and right side rails 42, 42. 17,17
And the rear ends of the left and right air spring seats 14,
14 are respectively connected to the front ends.

Regarding the specific mounting, the left and right lower torque rods 12, 12 are
The rod eye 18,18 is the front hanger 1
7 and 17 are connected with a pin (not shown) through a rubber bush (not shown), while the rear end torque rod eyes 19 and 19 are connected to the air spring seats 14 and 14, respectively. Front eyes 26,2 formed at the front end
It is about to be connected by a pin (not shown) with a rubber bush (not shown) interposed therebetween.

The left and right upper torque rods 13,
13 is located behind the rear axle 43 (L _r ), which sets its axle compliance center O _c, and is located behind it. More specifically, the left and right upper torque rods 13, 13 are the virtual inclined lines 2 extending forward when viewed from the side of the medium-sized bus 40.
3 is located in the front downhill where it is the slope intersecting an imaginary transverse axis 24 which extends laterally through its axle bouncing center O _b , while the axle is viewed from above the medium-sized bus 40. The imaginary axes 25, 25 extending rearward along the line are the axle compliance centers O _c
Is located in the rear recess where it is inclined through and the front end is connected to its axle pad 15,15 and its rear end is connected to its air spring bracket 16,16, respectively.

Regarding the specific mounting, the left and right upper torque rods 13 and 13 have the front end torque rod eyes 21 and 21 and the axle pad 1 respectively.
5, 15 are connected by a pin (not shown) through a rubber bush (not shown), while the rear end torque rod eye 22, 22 is attached to the air spring bracket 16, 16. It is about to be connected by a pin (not shown) with a rubber bush (not shown) interposed.

Further, the left and right upper torque rods 13, 13 are provided between the left and right axle pads 15, 15 and the left and right side rails 42, 42 as shown by a broken line in FIG. Can be replaced with other left and right upper torque rods 30, 30 that are connected correspondingly. In that case, the position (L ′ _r ) of the axle compliance center O ′ _c can be set further rearward than the axle compliance center O _c set by the upper torque rods 13, 13.

Further, in the rear suspension 10, the lateral rigidity of the axle compliance center O _c is such that the rubber bushes used for the left and right upper torque rods 13, 13 have the left and right lower torques. It is set larger than that of its axle bouncing center O _b by making it harder than that used for the rods 12, 12. Of course, lateral rigidity of the axle compliance center O _c may be set larger than that of the axle bouncing center O _b by other means. In that case, the lower left and right
Rubber bushes of the same hardness are used for the torque rods 12, 12 and the left and right upper torque rods 13, 13.

Next, the operation of the rear suspension 10 will be described with reference to the running of the medium-sized bus 40. When the medium-sized bus 40 travels on a paved road at a certain speed, and there is a bumpy road surface on the road, first, as shown in FIG.
44 is bound. Then, the rear axle 43 by the bound undergoes lifting displacement [delta] around its axle bouncing center O _b, and, although lifted upward by the vertical component [delta] _z of the push-up displacement [delta], the push-up displacement [delta] The change in the backward kinetic energy of the rear axle 43 is absorbed by the horizontal component δ _x of the rear axle 43.

The rear axle 43 is then rebound, as shown in FIG. Then, due to the rebound, the rear axle 43 receives the pushing displacement δ ′ around the axle bouncing center O _b , and is pushed downward by the vertical component δ ′ _z of the pushing displacement δ ′. The horizontal component δ ′ _x of the pushing displacement δ ′ absorbs the change in the forward kinetic energy of the rear axle 43. In that way
The front-rear shock that the medium-sized bus 40 receives due to the bound and rebound is reduced, pitching is also suppressed, and as a result, riding comfort is improved.

Also, the axle bouncing center O
_{Since b} is set in front of the rear axle 43 at a position (L _f , h) higher than the axle height, when the medium-sized bus 40 starts, a vertical load is driven on the rear axle 43. Increased in response to force, resulting in improved startability.

Further, the axle bouncing center O _b is the trumping center O _t of the medium-sized bus 40, as shown in FIG. 5, and the equivalent inertia I _t of the unsprung vibration is the unsprung vibration. Since the inertia I _{o of} the spring, the unsprung mass m, and the height h of the trumping center O _t are calculated as I _t = I _o + h ² m, the trumping center O _t , that is, the axle bouncing center O _By setting the height h of _b to be low, the left-right shock of the medium-sized bus 40 is reduced and the riding comfort is improved.

[0022] In addition, the axle compliance center O _c is set to the rear of the rear axle 43 and the axle compliance center O _c
Since the lateral rigidity of the vehicle is set to be larger than that of the axle bouncing center O _b , when the medium-sized bus 40 turns along the bend of the road, a lateral force is generated between the tire and the road surface. , And the left and right lower torque rods 12, 12 due to the lateral force that the tire receives.
And the rubber bushes of the left and right upper torque rods 13, 13 are bent. In this case, the rubber bushes of the left and right upper torque rods 13, 13 are deflected less than those of the left and right lower torque rods 12, 12, so that the left and right lower torque rods 12, 12 are bent. , 12 act on its rear axle 43 where it is being steered in the same direction by a front axle (not shown), while at the same time its upper torque rods 13, 13 are steered in the opposite direction to its front axle. It acts on the rear axle 43 where it is made.
In this case, the reverse steering of the rear axle 43 by the left and right upper torque rods 13, 13 becomes the same steering of the rear axle 43 by the left and right lower torque rods 12, 12. As it overcomes, its rear axle 43 is steered in the opposite direction to its front axle. That is, the compliance understeer is generated in the rear axle 43 promptly, that is, in agile manner, so that the medium-sized bus 40 is smoothly and swiftly changed to the turning, and the medium-sized bus 40 is The compliance under
The steering stability by steering is improved.

Also, the aforementioned rear suspension 1
In 0, a position higher than the axle height thereof axle bouncing center O _b is in front of the rear axle 43 (L
_f , h), the axle bouncing center O _b is set near the conjugate point of the front suspension and the rear suspension, which is obtained from the relationship between longitudinal load movement (pitching). May be done. Then, the other rear suspension in which the axle bouncing center O _b is set in the vicinity of the conjugate point is given the same riding comfort and startability as the rear suspension 10.

The conjugate point (Conjugate Poi)
As shown in FIG. 6, first, nts) will be described from the relationship of the longitudinal load movement, that is, the relationship of the spring deflection. The positional relationship between the conjugate points A and B and the spring center C is shown in FIG.
, And the conjugate points A and B are
It can be obtained by the relationship of a · b = p · q. In this case, the spring center C is a point where the front spring and the rear spring have the same deflection when a force is applied to that point.
On the other hand, it is explained from the relationship of distribution of masses m ₁ and m ₂ . The positional relationship between the conjugate points E ₁ and D ₁ and the center of gravity G is shown in the intermediate stage in FIG. 6, and the conjugate points E ₁ and D ₁ are obtained by the relationship of r · s = k ² . Where,
The inertia factor I is shown by the mass M and the radius of gyration k.
Also, there are innumerable conjugate points. However, the conjugate point satisfying both of them is only a pair of points J and H as shown in the lower part of FIG. That is, it is where the relation of p · q and the relation of r · s are compatible, and it is p
The intersection point J of the q curve and the r · s curve is obtained, and then the point H is obtained as the point for it. A conjugate point at which the pair of points J and H is finally obtained, that is, a double conjugate point Poi
nts), this double conjugate point is recognized as a pitching center in an actual vehicle.

In the above-mentioned rear suspension 10 and another rear suspension, the leaf spring is omitted, so that the frame 41 of the medium-sized bus 40 is lowered, and the leaf suspension is different between when the vehicle is empty and when it is loaded. Avoiding height changes due to spring deflection, and
The twisting beam is also omitted and simplified, and the weight is reduced. Further, the rear suspension 10 and another rear suspension are similarly applied to a small bus.

As will be apparent from the specific embodiments of the present invention described above with reference to the drawings, those of ordinary skill in the art to which the present invention pertains have the subject matter of the present invention. Is the nature of the invention (na
It is easily embodied in other embodiments that are derived from the true) and substance and that are objectively recognized as having them internalized. Of course, the contents of the present invention are essential to the establishment of the invention in accordance with the problems of the invention.

[0027]

As will be understood from the above, in the rear suspension used in the commercial vehicle of the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame. Let the left and right lower
A torque rod connects the underside of the rear axle to the frame in an arrangement that sets the axle bouncing center in front of the rear axle and above the axle height, and the left and right upper torque Since the rod connects the upper side of the rear axle to the frame in an arrangement that sets the axle compliance center behind the rear axle, the rear suspension used in the commercial vehicle of the present invention is When the rear wheels bounce and rebound on bumpy roads or uneven terrain while driving, the front and rear shocks and left and right shocks that the commercial vehicle receives due to the bounce and rebound are reduced and bounce and pitching are suppressed. The ride comfort has been improved and its rear
The vertical load on the axle is increased in response to the driving force to improve the startability. Furthermore, when the commercial vehicle turns, the rear axle causes compliance understeer and the commercial vehicle turns. The transition was smooth and fast, and the commercial vehicle had enhanced steering stability due to its compliance understeer, as well as leaf springs, swing arms, and twisting beams. The structure is simplified and the weight is reduced, and the height change due to the deflection of the leaf spring is avoided between when the vehicle is empty and when it is loaded, and as a result, it is very useful for medium and small buses. It is practical.

In the rear suspension used in the commercial vehicle of the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torques are supported. The rod connects the underside of its rear axle to its frame in an arrangement that at least sets the axle bouncing center near the conjugate points of the front and rear suspensions, and the left and right upper torque rods However, since the upper side of the rear axle is connected to the frame in an arrangement in which the axle compliance center is set behind the rear axle, the rear suspension used for the commercial vehicle of the present invention is a commercial vehicle running. Rear wheel bounces and rebounds on uneven road surface or uneven terrain while When the vehicle is hit, the bounce and rebound reduce the front and rear shocks and left and right shocks that the commercial vehicle receives, and the bouncing and pitching are suppressed to improve riding comfort. The vehicle's rear axle is compliant with the compliance under
The commercial vehicle is steered to transition smoothly and swiftly into turns, and the commercial vehicle is
Understeer enhances maneuvering stability.In addition, leaf springs, swing arms, and twisting beams are omitted to simplify the structure and reduce weight. The change in height due to the deflection of the leaf spring during loading is avoided, and as a result, it is very useful and practical for medium and small buses.

Further, in the rear suspension used in the commercial vehicle of the present invention, the left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque The rear of the rear axle is positioned so that the axle bouncing center is located in front of the rear axle and above the axle height.
Connecting the lower side of the axle to the frame, the left and right upper torque rods connecting the upper side of the rear axle to the frame in an arrangement that sets the axle compliance center behind the rear axle, and Since the lateral rigidity of the axle compliance center is set to be larger than that of the axle bouncing center, the rear suspension used for the commercial vehicle of the present invention has a rear suspension when the commercial vehicle is running. When a wheel bounces and rebounds on a bumpy road surface or uneven terrain, the bounce and rebound reduce the front and rear shocks and left and right shocks that the commercial vehicle receives, and suppress bounce and pitching to improve ride comfort. Also, vertical load is applied to the driving force on the rear axle. And the startability is improved, and when the commercial vehicle turns, the rear axle swiftly causes compliance understeer, and the commercial vehicle transitions smoothly and swiftly. And the commercial vehicle has the compliance
Steering enhances steering stability, and further reduces leaf springs, swing arms, and twisting beams to simplify the structure and reduce weight. The leaf in time
Height changes due to spring deflection are avoided, which is very useful and practical for small and medium-sized buses.

Furthermore, in the rear suspension used in the commercial vehicle of the present invention, the left and right air springs are disposed behind the rear axle to support the rear axle on the frame, and the left and right lower suspensions are supported. The torque rod connects the lower side of the rear axle to the frame in an arrangement that sets at least the axle bouncing center near the conjugate point of the front suspension and the rear suspension, and the left and right upper torque rods are connected to each other. , Connecting the upper side of the rear axle to the frame in an arrangement that sets the axle compliance center behind the rear axle, and the lateral stiffness of the axle compliance center is greater than that of the axle bouncing center. Is also set large, so it is used in the commercial vehicle of this invention. The rear suspension reduces the front and rear shocks and left and right shocks that the commercial vehicle receives when the rear wheels bounce and rebound on bumpy roads and uneven terrain while the commercial vehicle is running. Then, bouncing and pitching are suppressed to improve riding comfort, and vertical load is increased corresponding to the driving force on the rear axle to improve startability, and the commercial vehicle turns. At the same time, the rear axle swiftly causes compliance understeer to shift the commercial vehicle smoothly and swiftly, and the compliance understeer provides the commercial vehicle with steering stability. Heightened, and even leaf springs,
The swing arm, twisting beam, etc. are omitted to simplify the structure and reduce the weight, and the height change due to the deflection of the leaf spring is avoided between when the vehicle is empty and when it is loaded. As a result, it is very useful and practical for small and medium-sized buses.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a specific example of a rear suspension used in a commercial vehicle of the present invention applied to a medium-sized bus.

FIG. 2 is a plan view of the rear suspension shown in FIG.

FIG. 3 is an operation explanatory view showing the operation of the rear suspension when the rear wheels bounce while the medium-sized bus is traveling.

FIG. 4 is an operation explanatory view showing the operation of the rear suspension when the rear wheels rebound during traveling of the medium-sized bus.

FIG. 5 is a schematic front view of the medium-sized bus seen from the front to show the position of the center of the trumping.

FIG. 6 is a front-rear load movement relationship diagram shown for the medium-sized bus.

[Explanation of symbols]

11 Air spring 12 lower torque rod 13 upper torque rod 14 Air spring seat 15 axle pad 16 Air spring bracket 11 front hanger O _b axle bouncing center O _c axle compliance center O ' _c Axle compliance center O _t trumping center

Claims (14)

[Claims] 1. Left and right air springs are arranged behind the rear axle to support the rear axle on a frame, and left and right lower torque rods are located in front of the rear axle and more than the axle height. Also connects the underside of the rear axle to the frame in an arrangement that sets the axle bouncing center high, and the left and right upper torque rods place the axle compliance center behind the rear axle. Rear suspension used in commercial vehicles where the upper side of the rear axle is connected to the frame in a set configuration. 2. The left and right lower torque rods are arranged in the front recess at the front rising, and the left and right upper torque rods are arranged in the rear recess.
Rear suspension used in commercial vehicles described in. 3. The left and right lower torque rods are arranged in the front concavity in the front rising, and the left and right upper torque rods are arranged in the rear constriction in the front descending. Rear suspension used in the commercial vehicle described in 1. 4. The left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque rods are conjugate points of the front suspension and the rear suspension. Connect the underside of the rear axle to the frame in an arrangement that sets at least the axle bouncing center near, and the left and right upper torque rods will place the axle compliance center behind the rear axle. A rear used for commercial vehicles where the upper side of the rear axle is connected to the frame in a set arrangement.
suspension. 5. The left and right lower torque rods are arranged in the front recess at the front rising, and the left and right upper torque rods are arranged in the rear recess.
Rear suspension used in commercial vehicles described in. 6. The left and right lower torque rods are arranged in a front constriction at the front rising, and the left and right upper torque rods are arranged in a rear constriction at the front descending. Rear suspension used in the commercial vehicle described in 4. 7. The left and right air springs are arranged behind the rear axle to support the rear axle on the frame, and the left and right lower torque rods are located in front of the rear axle and are higher than the axle height. The lower part of the rear axle is connected to the frame in an arrangement that sets the axle bouncing center to a higher position, and the left and right upper torque rods are located behind the rear axle.
Used in commercial vehicles where the upper side of the rear axle is connected to the frame in a compliance centered configuration and the lateral stiffness of the axle compliance center is set to be greater than that of the axle bouncing center. Rear suspension to be used. 8. The left and right lower torque rods are arranged in the front recess at the front rising, and the left and right upper torque rods are arranged in the rear recess.
Rear suspension used in commercial vehicles described in. 9. The left and right lower torque rods are arranged in a front constriction in the front rising, and the left and right upper torque rods are arranged in a rear constriction in the front descending. Rear suspension used in the commercial vehicle described in 7. 10. The lateral stiffness of the axle compliance center of the axle bouncing center by making the rubber bushes of the left and right upper torque rods stiffer than that of the left and right lower torque rods. The rear suspension used for the commercial vehicle according to claim 7, which is set larger than that. 11. Left and right air springs are disposed behind the rear axle to support the rear axle on the frame, and left and right lower torque rods are conjugate points of the front suspension and the rear suspension. Connect the underside of the rear axle to the frame in an arrangement that sets at least the axle bouncing center near, and the left and right upper torque rods set the axle compliance center behind the rear axle. The rear axle used in commercial vehicles where the upper side of the rear axle is connected in an arrangement to the frame, and the lateral stiffness of the axle compliance center is set to be greater than that of the axle bouncing center. suspension. 12. The left and right lower torque rods,
The rear suspension for use in a commercial vehicle according to claim 11, wherein the rear suspension is disposed in a front recess at the front ascent and the left and right upper torque rods are disposed in the rear recess. 13. The left and right lower torque rods,
The rear suspension used in a commercial vehicle according to claim 11, wherein the rear upper suspension is disposed in a front recess in a frontward climb, and the left and right upper torque rods are disposed in a rearward recess in a frontward descend. 14. The lateral stiffness of the axle compliance center of the axle bouncing center by making the rubber bushes of the left and right upper torque rods stiffer than that of the left and right lower torque rods. The rear suspension used in the commercial vehicle according to claim 11, which is set to be larger than that.