JP2000062423A - Tandem axle suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the starting performance of a vehicle in an empty condition or in a light load application state regarding a tandem axle suspension device suitably used for a large vehicle such as a bus and a truck. SOLUTION: This suspension device is provided between a car body frame 4 and a pair of tandem axles composed of a drive shaft 1 and an non-drive shaft 2. In this case, the device is provided with a rigid member 8 suspended at the lower side of the car body frame 4 and an elastic member 7 attached to the rigid member 8 and connected to the drive shaft 1 and the non-drive shaft 2. The rigid member 8 is disposed by being inclined with respect to the car body frame 4 such that the drive shaft 1 is positioned lower than the non- driven shaft 2 while the elastic member 7 is in a free state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem axle suspension system suitable for use in large vehicles such as buses and trucks.

[0002]

2. Description of the Related Art In recent years, in large vehicles such as buses and trucks,
Tandem axles with two rear axles (rear axles) are being adopted. As described above, in the vehicle in which the rear axle has the tandem axle, the load can be distributed to the two axles, and the total load can be improved.

FIG. 2 is a schematic side view showing an example of a suspension (suspension device) for supporting the tandem axle as described above, and the left side of the figure is the front of the vehicle. Figure 2
As shown in FIG. 2, two axles (axle shafts) 101 and 102 are provided in the front-rear direction of the vehicle, and the shafts 101 and 102 are housed in axle shaft housings 111 and 112, respectively. Of these, the front axle shaft (rear front shaft) 101 is a drive shaft (drive shaft) driven by an engine (not shown).
In addition, the propeller shaft 105 and the operating mechanism (differential gear mechanism) 106 are connected. The rear axle shaft (post-rear shaft) 102 is a non-driving shaft (dead shaft) which is supported by a bearing (not shown) and can freely rotate. In addition, each axle shaft 10
Tires 103f and 103r are attached to the tires 1 and 102, respectively. In the following, reference numerals 103f,
Like 103r, the same member arranged on the front side (drive shaft 101 side) has a letter f after the numeral, and on the rear side (dead shaft 102 side). When there is no particular need to distinguish by adding the letter r after the number, the letters are omitted, for example, "tire 103", and only the number is shown.

Further, each axle shaft 101, 102
Is connected to a vehicle body (vehicle body frame) 104 via a suspension device, and this suspension absorbs impacts from the road surface and damps vibrations. Here, the suspension device is mainly composed of a leaf spring 107, an equalizer beam 108, a rubber spring 109, a shock absorber 110, and the like. Of these, the equalizer beam 108 is formed to have a substantially U-shaped cross section and is arranged so as to open downward.

A leaf spring 107 is attached to the equalizer beam 108. Here, the leaf spring 107 is the equalizer beam 108.
It is attached so as to be housed inside, and is fixed by a U bolt or the like at the center of the equalizer beam 108. Further, both ends of the leaf spring 107 are connected to the axle shaft housings 111 and 112 via brackets (not shown). The connection portion between the leaf spring 107 and the axle shaft housings 111 and 112 is the leaf spring 1
It is configured to be able to absorb a change in spring length when 07 is bent.

The equalizer beam 108 is suspended from the frame 104 by rubber springs 109f and 109r. These rubber springs 109
As shown in FIG. 2, the equalizer beam 108 is attached so as to have a substantially V shape in a side view, and the lower end of the rubber spring 109 is connected via a spring saddle 113.
It is connected to the. Here, this rubber spring 10
A rubber pad 9 and a steel plate are alternately laminated so as to be integrally formed, and the spring characteristic 9 is configured to have different spring characteristics in the shearing direction and the compression direction. By configuring the rubber spring 109 as described above and arranging it in a V shape, the spring characteristics can be individually set in the compression direction, the tension direction, and the shearing direction.

On the other hand, each axle shaft housing 11
Shock absorbers 110f and 110r are respectively interposed between the frames 1 and 112 and the frame 104. Here, the upper end and the lower end of the shock absorber 110 are rotatably attached to the frame 104 and the axle shaft housings 111 and 112, respectively, and when the tire 103 moves up and down, the shock absorber 110 acts by these actions. Vibration is damped.

The leaf spring 107 and the rubber spring 109 are arranged in series, and when the vehicle is empty or under a light load, the leaf spring 10 is mainly used as a spring.
7 works. That is, when the vehicle is empty or under a light load, both ends of the leaf spring 107 stroke vertically to absorb the impact. In addition, when the vehicle is loaded (when the load is medium and high), both ends of the leaf spring 107 come into contact with the equalizer beam 108, and further deformation of the leaf spring 107 is restricted. At this time, tire 1
The vertical movement of 03 is transmitted to the equalizer beam 108, and the rubber spring 109 mainly acts as a spring to absorb the shock. Thus, it is possible to achieve riding comfort and maneuverability without being affected by the load capacity as much as possible.

As described above, the rear axle is
By using the shaft as an axis, the loaded load can be distributed to the front axle shaft 101 and the rear axle shaft 102 to reduce the load per axis, and the total loaded weight can be increased. In FIG. 2, reference numerals 114f and 114r are bump rubbers (bound stoppers) for restricting the bound stroke of the suspension.

Further, the tandem axle suspension device is not limited to the leaf spring (leaf spring) 107 as described above, but may be an air spring (air spring).
There is one using, but the description is omitted here.

[0011]

However, in a tandem axle suspension system having such a drive shaft and a non-drive shaft, the load acting on the axle is dispersed, and thus the ground contact acting on the drive shaft is caused by this amount. There is a problem that the load is reduced and the starting property of the vehicle is reduced when the vehicle is empty (light load).

That is, at the time of starting the vehicle, the drive wheels need to have a force sufficient to overcome the total static frictional force of the non-drive wheels (including the front wheel axle). As a result, the contact area between the non-driving wheel and the road surface increases correspondingly, and the total static friction force of the non-driving wheel also increases. Furthermore, as the ground load acting on the drive shaft decreases, the frictional force of the drive wheels becomes smaller than the total static frictional force of the non-drive wheels, especially when the vehicle is idling (lightly loaded) and the drive wheels run idle. It is possible to do it. In addition, since a sufficient ground load acts on the drive wheels and a sufficient grip force is generated during loading (during medium and high load), the above-described problem hardly occurs.

As a technique for solving such a problem,
For example, it is conceivable to use an air spring as the spring and control the air pressure of the air spring according to the loaded load. With such technology, when the vehicle is empty (light load)
Moreover, for example, the air pressure of the air spring is controlled so as to lift the dead shaft (non-driving shaft) side to increase the ground load acting on the drive shaft (driving shaft) and improve the startability.

However, such a technique is applied to a suspension device using an air spring, and is also applied to a suspension device using a mechanical spring such as the leaf spring or coil spring described above. It is not possible. Note that Japanese Patent Application Laid-Open No. 9-136521 discloses a technique related to a tandem axle suspension device, but this technique is intended to reduce the weight of the suspension device and improve riding comfort. It wasn't a solution.

The present invention has been made in view of the above problems, and an object thereof is to provide a tandem axle suspension device for improving the startability of the vehicle when the vehicle is empty or under a light load. .

[0016]

In the tandem axle suspension system according to the present invention as set forth in claim 1, a rigid member is suspended below a vehicle body frame, and an elastic member is attached to this rigid member.
In addition, the elastic members are connected to the drive shaft and the non-drive shaft, respectively, and a biasing force acts on the drive shaft and the non-drive shaft. Here, when the elastic member is in a free state, the rigid member is arranged so as to be inclined with respect to the vehicle body frame so that the drive shaft is located below the non-drive shaft. As a result, in the grounded state, the amount of bending of the elastic member is larger on the drive shaft side than on the non-drive shaft side, the urging force acting on the drive shaft is larger, and the ground load increases. As a result, a sufficient ground load can be obtained on the drive shaft side, and the startability is improved.

In the tandem axle suspension system according to the second aspect of the present invention, the suspension system as a whole is mounted on the vehicle body frame so that the drive shaft is located below the non-drive shaft when the elastic member is free. And arrange it with an inclination. As a result, in the grounded state, the bending amount of the elastic member is larger on the drive shaft side than on the non-drive shaft side, and the biasing force acting on the drive shaft is larger than that on the non-drive shaft, and the ground load Increase. As a result, a sufficient ground load can be obtained on the drive shaft side, and the startability is improved.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A tandem axle suspension system as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view showing the overall configuration thereof.
In FIG. 1, 1 is a drive shaft (driving shaft), 2 is a dead shaft (non-driving shaft), 3f and 3r are tires, 4 is a frame (body frame), 5 is a propeller shaft, 6 differential gear mechanism, and 7 is elastic. A leaf spring as a member, 8 is an equalizer beam, 9f and 9r are rubber springs, 10f and 10r are shock absorbers, and 1
Reference numerals 1 and 12 are axle shaft housings, 13 is a spring saddle, and 14f and 14r are bump rubbers (bound stoppers), which are substantially the same as those of the prior art described with reference to FIG. As in the case of the related art, the ones such as “tires 3f, 3r” with reference numerals “f” and “r” distinguish the arrangement positions of the members in the front-rear direction, and are particularly distinguished. When there is no need, the letters are omitted and only the numbers are shown, for example, "tire 3".

By the way, the tandem axle suspension device of the present invention is mainly different from the prior art in the state of attachment to the vehicle body frame 4, and is otherwise substantially the same in construction. FIG. 1 shows the state of the suspension (suspension device) when the tire 3 is in an unloaded state (or referred to as a free state) in which the tire 3 is not in contact with the ground. Then, the drive shaft 1 is set to be positioned below the dead shaft 2.

The initial displacement of the drive shaft 1 and the dead shaft 2 at the height position is given by mounting the entire suspension with respect to the vehicle body frame 4. Specifically, as shown in FIG. 1, the mounting heights of the front and rear rubber springs 9f and 9r with respect to the vehicle body frame 4 are set differently, and the mounting position of the rubber spring 9f on the drive shaft 1 side is a dead position. It is set lower than the mounting position of the rubber spring 9r on the shaft 2 side.

The leaf spring 7, the equalizer beam 8, the rubber springs 9f and 9r, and the spring saddle 13 are configured to be symmetrical in the front-rear direction (left-right direction in the drawing) before being attached to the vehicle body frame 4. Has been done. Further, the camber (warpage amount) of the leaf spring 7 is set to be equal on the drive shaft 1 side and the dead shaft 2 side, and further, from the attachment position of the leaf spring 7 of each axle shaft housing 11, 12 to the axle shaft 1, The distances up to 2 are also set to be equal to each other.

Therefore, as described above, the rubber springs 9f and 9r are offset in the height direction, and the mounting position of the rubber spring 9f with respect to the vehicle body frame 4 is set to a position lower than the rubber spring 9r. In the (natural state), the entire suspension including the equalizer beam 8 is tilted (see the angle α in FIG. 1), and the drive shaft 1 is located below the dead shaft 2.

Then, as described above, the initial displacement is given in advance so that the drive shaft 1 is located below, so that the biasing force acting on the drive shaft 1 can be applied when the tires 3f and 3r are grounded. Will grow. Therefore, the urging force acting on the drive shaft 1 side increases, and as a result, a sufficient ground load can be applied to the drive shaft 1 side.

In this embodiment, the mounting positions of the shock absorbers 10f and 10r on the vehicle body frame 4 are not particularly changed from the conventional ones. this is,
This is because the relative positional relationship between the vehicle body frame 4, the shock absorbers 10f and 10r, and the axle shaft housings 11 and 12 is the same as before when the tire 3 is grounded.

Since the tandem axle suspension device according to the embodiment of the present invention is constructed as described above, the vibration is absorbed by the leaf spring 7 and the rubber spring 9 when the vehicle is empty (light load), for example. Then, the shock absorber 10 attenuates the vibration. Further, at the time of loading (during medium and high load), the leaf spring 7 bends and comes into contact with the equalizer beam 8, and the equalizer beam 8 restricts further deformation of the leaf spring 7. In this case, the rubber spring 9 absorbs the vibration during traveling, and the shock absorber 10 attenuates the vibration.

Then, the mounting position of the rubber spring 9 on the vehicle body frame 4 is offset between the drive shaft 1 side and the dead shaft 2 side so that the entire suspension is tilted so that the drive shaft 1 is located below when there is no load. By giving the initial displacement in advance, the urging force that always acts on the drive shaft 1 side increases, and the ground load on the drive shaft 1 side increases more than that on the dead shaft 2 side by this amount.
That is, when the front and rear tires 3f, 3r are in contact with the ground, the axial load moves to the drive shaft 1 side and the ground load of the drive shaft 1 increases.

By increasing the ground load on the drive shaft 1 side as described above, it is possible to suppress the idling of the drive wheels 3f at the time of starting the vehicle, so that the vehicle can be started (especially when the vehicle is idle or at a light load). It is possible to improve the starting property of time). Further, the present device has an advantage that the starting property of the vehicle can be improved with the extremely simple configuration as described above, and the cost and the weight hardly increase.

Although the leaf spring 7 is used as the elastic member in the present embodiment, the elastic member is not limited to the leaf spring 7, and the entire suspension is inclined with respect to the vehicle body frame 4. Therefore, if the biasing force acting on the drive shaft 1 side can be set larger than the biasing force acting on the dead shaft 2 side,
Other than the leaf spring 7, various elastic members such as a coil spring can be applied.

In the above-described embodiment, the case where the mounting position of the rubber spring 9 is offset to tilt the entire suspension has been described. However, only the equalizer beam 8 is tilted independently and the drive shaft is preliminarily driven. The initial displacement may be given so that 1 is located below the dead axis 2. In this case, the equalizer beam 8 may be tilted by, for example, forming the mounting surface of the spring saddle 13 with respect to the equalizer beam 8 or by forming the mounting surface of the equalizer beam 8 with respect to the spring saddle 13 by tilting.

Even in the case of such a configuration, in the state where the tire 3 is in contact with the ground, the load on the drive shaft 1 side is larger than that on the dead shaft 2 side (that is, the ground load),
There is an advantage that the startability of the vehicle can be improved, and there is an advantage that the weight and cost are not increased. Even when the equalizer beam 8 alone is tilted in this way, various springs such as a coil spring can be applied as the elastic member.

The embodiments of the present invention are not limited to those described above, and various modifications can be made without departing from the spirit of the present invention. The detailed structure of the suspension system and the arrangement of parts are also possible. Can be changed as necessary.

[0032]

As described in detail above, according to the tandem axle suspension system of the present invention as set forth in claim 1, the drive shaft is positioned below the non-drive shaft when the elastic member is in the free state. Since the rigid member is arranged so as to be inclined with respect to the body frame, the ground load acting on the drive shaft can be increased, and there is an advantage that the startability can be improved especially when the vehicle is empty. It also has the advantage of causing little increase in cost and weight.

According to the tandem axle suspension device of the present invention as defined in claim 2, the drive shaft is located below the non-drive shaft as a whole when the elastic member is in a free state, so that the whole body is attached to the body frame. Since it is installed so as to be inclined, the ground load acting on the drive shaft can be increased and the startability can be improved especially when the vehicle is empty, as well as the cost and weight. It also has the advantage that the increase in the

[Brief description of drawings]

FIG. 1 is a schematic side view showing an overall configuration of a tandem axle suspension device as an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a conventional tandem axle suspension device.

[Explanation of symbols]

1 drive axis (drive axis) 2 Dead axis (non-driving axis) 4 frames (body frame) 7 Leaf spring as elastic member 8 Equalizer beam (rigid member)

Claims (2)

[Claims] 1. A tandem axle suspension device interposed between a body frame and a pair of tandem axles including a drive shaft and a non-drive shaft, wherein a rigid member suspended below the body frame, An elastic member attached to the rigid member and coupled to the drive shaft and the non-drive shaft, respectively, and biasing the drive shaft and the non-drive shaft downward; The rigid member is disposed so as to be inclined with respect to the vehicle body frame so as to be positioned below the drive shaft.
Tandem axle suspension system. 2. A tandem axle suspension system interposed between a vehicle body frame and a pair of tandem axles including a drive shaft and a non-drive shaft, wherein an elastic member for urging the drive shaft and the non-drive shaft downward. The entire elastic member is tilted with respect to the body frame so that the drive shaft is located below the non-drive shaft when the elastic member is in a free state. Tandem axle suspension system.