JPH10278534A - Driving force adding device for rear two-axle - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When switching to a driving force added state,
It is an object of the present invention to provide a driving force adding device for a two-axle vehicle, which prevents a brake lock of a wheel after the internal pressure of an air spring is reduced. The internal pressure of an air spring (24) on the shaft (18) is gradually increased in accordance with an increase in a load or a tandem shaft load.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force applying device for a rear two-axle vehicle, and more particularly to a rear front axle comprising a driven shaft by discharging air from an air spring of a suspension device having a driven shaft. The present invention relates to a driving force adding device for a two-axle vehicle in which the axle weight of a shaft is increased to increase the driving force of a driving wheel attached to a driving shaft.

[0002]

2. Description of the Related Art For example, Japanese Utility Model Publication No. 27444/1990 discloses that the air load of an air spring of a suspension device that suspends a rear shaft consisting of a driven shaft is exhausted to increase the axial load of a rear front shaft consisting of a driving shaft. A driving force applying device for a two-axle vehicle is disclosed in which the driving force of the driving wheels is increased in such a manner.

When switching is performed by such a driving force applying device so as to increase the driving force of the driving wheels, the air from the air spring on the driven shaft side is discharged, and the internal pressure thereof is reduced.
Accordingly, most of the vehicle weight is borne by the drive shaft. Therefore, the frictional force between the driving wheels and the road surface increases, and a large driving force can be obtained. At this time, as the vehicle weight increases, the internal pressure of the air spring on the drive shaft side gradually increases.

[0004]

As described above, the driving force applying device discharges air from the air spring on the rear shaft side composed of the driven shaft, thereby increasing the axial load of the rear front shaft composed of the driving shaft. The driving force of the driving wheels is increased. When switching to the driving force applied state, the air from the air spring on the shaft side is discharged later. At this time, the pressure is maintained at a substantially constant pressure such that the shaft-side air spring is not crushed later. In other words, priority is given to improvement of the startability of the drive wheels, and the pressure of the air spring on the shaft side is later adjusted so that the axle weight movement to the drive shaft is most effectively performed.

[0005] If the starting pressure of the drive wheel is given priority and the air pressure of the air spring on the rear axle side is maintained at a minimum value, the rear wheel is easily locked during braking due to insufficient shaft weight on the rear axle side. There are drawbacks. When the wheels are brake-locked later, there is a problem that the posture of the vehicle is disturbed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is intended to prevent a rear wheel including a driven wheel from being brake-locked even after switching to a driving force applied state. It is an object to provide a driving force applying device.

[0007]

SUMMARY OF THE INVENTION The present invention increases the axle weight of a rear front shaft consisting of a drive shaft by discharging air from an air spring of a suspension device that suspends a rear shaft consisting of a driven shaft. In the driving force applying device for a two-axle vehicle, the internal pressure of the air spring on the rear axle side in the driving force applied state is gradually increased in accordance with the increase in the load. The present invention relates to a driving force adding device for a rear two-axle vehicle.

Another aspect of the present invention is to increase the axle weight of a rear front shaft composed of a drive shaft by discharging air from an air spring of a suspension device that suspends a rear shaft composed of a driven shaft to increase the driving force of a drive wheel. In the driving force adding device for a rear two-axle wheel, the driving shaft is configured to increase the axle load applied to the rear two axles or the ratio of the axle load applied to the rear front axle to the total weight of the vehicle with respect to the total weight of the vehicle. The rear two-axle vehicle is characterized in that the internal pressure of the air spring on the axle side is increased in accordance with the increase of the load so that the ratio becomes approximately equal to the drive shaft weight ratio when the vehicle is empty. The present invention relates to a driving force applying device.

[0009]

FIG. 1 shows a track provided with a driving force applying apparatus according to an embodiment of the present invention. The truck has a frame 10. A cab 11 is mounted on the front end of the frame 10, and a carrier 12 is mounted on a rear portion of the frame 10.

A front end portion of the frame 10 is supported by a front wheel 14. On the other hand, the rear part of the frame 10 is supported by the rear front wheel 15 and the rear rear wheel 16.

The rear front wheel 15 is mounted on a rear front shaft 17. On the other hand, the rear wheel 16 is attached to the shaft 18 later. The rear front wheel 15 constitutes a driving wheel, and the rear wheel 1
Reference numeral 6 forms a driven wheel. That is, the driving force from the engine is transmitted to only the rear front wheels 15 through the power line.

The rear front shaft 17 is suspended from the frame 10 by a leaf spring 21 and an air spring 22, as shown in FIG. That is, the air spring 22 is interposed between the rear end portion of the leaf spring 21 and the vehicle body. Similarly, the shaft 18 is later suspended by a leaf spring 23 and an air spring 24. An air spring 24 is interposed between the rear end of the leaf spring 23 and the vehicle body.

An air spring 22 on the rear front shaft 17 side and an air spring 24 on the rear rear shaft 18 are connected to a communication cutoff switching valve 2.
8 and communicate with each other. The air spring 22 on the rear front shaft 17 side is provided with the first vehicle height adjusting valve 2.
9 and the second vehicle height adjusting valve 30 are connected to the air tank 31.

An exhaust valve 32 is further connected to the communication cutoff switching valve 28. The exhaust valve 32 exhausts the air spring 24 on the shaft 18 later. The air spring 24 is directly connected to the air tank 31 via an air supply valve 33 formed of an electromagnetic valve. An electromagnetic valve 34 is connected so as to supply a signal pressure to a signal port of the communication cutoff switching valve 28. An electromagnetic valve 35 is connected so as to supply a signal pressure to a signal port of the exhaust valve 32.

Further, the driving force applying device includes computers 39 and 40. The computer 39 controls a pair of vehicle height adjusting valves 29 and 30 and controls the vehicle height adjusting operation. On the other hand, the computer 40 controls the air supply valve 33 and the solenoid valves 34 and 35, respectively, and controls the addition and release of the driving force. The pressure sensors 45 and 46 attached to the air springs 22 and 24 are connected to the computer 40. The vehicle height sensor 41 is connected to the computer 39, and the vehicle speed sensor 42 is connected to the computer 40.

Next, normal control of the air springs 22, 24 of the suspension device for a rear two-axle vehicle having the above-described configuration will be described. In a normal case where the driving force is not applied, the communication cutoff switching valve 28 is in a communication state, and the air springs 22 and 24 are connected to each other via the communication cutoff switching valve 28. The first vehicle height adjusting valve 29 and the second vehicle height adjusting valve 30 perform a vehicle height adjusting operation. That is, while the computer 39 reads the vehicle height by the vehicle height sensor 41,
In response to this, the two vehicle height adjusting valves 29, 30 are switched, whereby the air spring 22,
Air is supplied to or exhausted from the air springs 22 and 24 so that the vehicle height is maintained at a standard height.

Next, when switching to the driving force applied state, the communication cutoff switching valve 28 is switched to the cutoff state, and the air in the air spring 24 is exhausted from the exhaust valve 32 through the communication cutoff switching valve 28. This operation is performed by switching the communication cutoff switching valve 28 to the cutoff state by the solenoid valve 34 and switching the exhaust valve 32 to the exhaust side by the solenoid valve 35.

At this time, the supply of air to the air spring 22 on the side of the front shaft 17 after being simultaneously shut off from the air spring 24 is controlled by the first vehicle height adjustment valve 29 and the second vehicle height adjustment valve 30.
And so on. Later, the air spring 24 on the shaft 18 side
When the air is exhausted, the load applied to the rear front shaft 17 increases, so that the air spring 22 is compressed and the vehicle height decreases. Then, the vehicle height sensor 41 detects this, and the computer 39 switches the vehicle height adjustment valves 29 and 30 to the communication side, and supplies air from the air tank 31 into the air spring 22.

In addition, by controlling the air supply valve 33 by the computer 40 according to the vehicle weight, air is supplied to the air spring 24 as needed, whereby the internal pressure of the air spring 24 on the shaft 18 side is adjusted later. We try to increase according to the weight.

The front shaft (R ₁ axis) after 4 due to the switching to such a driving force applying state 17 side of the air springs 22
When shows changes in later shaft (R ₂ axis) 18 side of the inner pressure of the air spring 24. Note that the characteristic shown by the dotted line in the figure is the characteristic when the driving force addition is released. 3 to 5, the driving force applying device is a F / G (Fine Grip,
Product name).

[0021] In the driving force applying apparatus that this way to increase the driving force of the driving wheels, as shown in FIG. 3, the internal pressure of the air springs 24 of the later-axis in the driving force applying state (R ₁ axis) If control is performed so as to maintain the pressure at such a level that the air spring 24 is not crushed, in the region of the tandem axle load or the vehicle weight where the air spring 24 is maintained at such an abnormally low pressure, the axle load on the axle 18 side becomes insufficient later. Therefore, the brake lock of the wheel 16 is easily generated later.

Therefore, in the driving force applying device according to the present embodiment, as shown in FIG. 4, in the driving force applied state, the internal pressure of the air spring 24 on the shaft 18 is increased according to the load or the tandem axle load. Like that. In other words, this is a region until the pressure of the air spring 22 on the rear front shaft 17 side reaches the limit value, and the air spring 24 on the rear shaft 18 side which has been conventionally maintained at a constant extremely low pressure.
The internal pressure is gradually increased.

Such control is performed by the communication cutoff switching valve 28.
Is switched to the shut-off state and the driving force is applied, and then the air supply valve 33 is opened by the computer 40, and the air supply valve 3 is opened.
3 by supplying compressed air directly from the air tank 31 to the air spring 24. At this time, the pressure in the air spring 24 is detected by the pressure sensor 46, and this pressure is
Will be fed back. Therefore, by such a control operation, the pressure of the air spring 24 can be gradually increased according to the tandem axle load as shown in FIG.

The point A in FIG. 4 (axle load W ₂ , pressure P
₂₂₎ and point B (axle load W _2, from the data relating to the brake lock at a pressure P ₂₁₎ past, △ P ₂ = determined from acceptable relationship between the value and the axle load W ₁ of the P ₂₁ -P _22, to determine .
Here, ΔP ₂ represents the internal pressure difference. It is desirable that the point A (axle load W ₂ , pressure P ₂₂ ) obtained in this way and the point C (axle load W ₁ , pressure P ₁₂ ) when the vehicle is idle are connected by a straight line Z. The reason is that the axle load of the rear front shaft 17 is increased by increasing the axle load of the rear axle 18 so as to be proportional to the increase of the axle load so that the difference in axle load of the rear front axle 17 can be reduced from the brake lock point to the actual value ΔP ₂ or less. This makes it possible to achieve both startability and braking performance.

As described above, since the internal pressure of the air spring 24 on the rear shaft 18 is increased according to the loaded load or the tandem shaft weight, the extreme shortage of the rear shaft 18 can be eliminated. And for this, the wheel 16
Brake lock hardly occurs.

Next, another embodiment will be described with reference to FIG. In this embodiment, the internal pressure of the air spring 24 on the shaft 18 is controlled later so that the drive shaft weight ratio becomes constant.

In the driving force applied state, the rear two shafts 17, 1
The ratio of the axle load applied to the rear front shaft 17 to the sum of the axle loads applied to the drive shaft 8 is defined as a drive axle load ratio k. Drive shaft weight ratio k when empty
₁ is obtained using FIG. Note here P ₁ is the pressure of the air springs 22, 24 when switching the communication cutoff switch valve 28 in communication with the bare. Air spring 2
If the effective cross-sectional areas under the loads of 2, 24 are equal,
The internal pressure of these air springs 22 and 24 is proportional to the load. When the switching to the driving force applying state, the internal pressure of the air spring 22 becomes P ₁ + △ P _1, the internal pressure of the air spring 24 is P ₁ - it becomes △ P _1. Therefore, k ₁ is represented by the following equation.

(Equation 1) Next, consider the case where the tandem axle weight is x. When the internal pressure of the air springs 22 and 24 when communicating cutoff switch valve 28 at this time is in communication with a P _x, when the driving force applying state by switching connection and disconnection switching valve 28 to the blocking state, the air springs 22 The internal pressure becomes P _x + △ P _x ,
The internal pressure of the air spring 24 is P _x - become △ P _x.
Accordingly, the drive shaft weight ratio k _{x at} this time is expressed by the following equation.
Although was the proportion of axle load applied to the front axle after a driving axle load ratio K ₁ drive shaft for the axle weight applied to the two axes after this case may be the ratio of the drive axle load to the vehicle gross weight.

(Equation 2) Here, the internal pressure of the air spring 24 is controlled by the computer 40 so as to satisfy the relationship of k ₁ = k _x . k
_{From 1} = k _x ,

(Equation 3) Therefore

(Equation 4) By controlling the internal pressure of the air spring 24 by the computer 40 as in the above equation, the internal pressure of the air spring 24 is controlled with respect to the tandem axle load while controlling the pressure of the air spring 24 so that the drive shaft weight ratio becomes constant. Can be gradually increased. By such control, the internal pressure of the air spring 24 is not maintained at an extremely small constant value, and the brake lock of the wheel 16 becomes difficult to occur later. For this reason, disturbance of the vehicle posture and occurrence of a dangerous state due to the brake lock are avoided.

The control for keeping the drive shaft weight ratio constant is performed by setting the drive shaft weight ratio smaller than the limit value at which the internal pressure of the air spring 24 on the shaft 18 side becomes constant, as shown by the dotted line in FIG. Is set within the range. At the limit value, while the internal pressure of the air spring 24 of the rear shaft 18 is kept constant as shown by the dotted line, the rear front shaft 17
The internal pressure of the side air spring 22 almost reaches the limit value of 5 kg / cm ^{2 at} a tandem axle load of 9.4 tons. Accordingly, by keeping the drive shaft weight ratio constant within a range not exceeding such a limit value, the above-described control becomes possible.

[0029]

According to the present invention, the internal pressure of the air spring on the rear shaft side in the driving force applied state is gradually increased in accordance with the increase of the load.

Therefore, according to such a driving force applying device, the internal pressure of the air spring on the shaft side is gradually increased later as the loaded load increases. Therefore, it is possible to avoid the brake lock of the rear wheel according to such an increase in the pressure.

Another aspect of the present invention relates to a method for driving a vehicle in a state where a driving force is applied.
When the ratio of the axle load applied to the axle or the ratio of the axle load applied to the rear front axle to the gross vehicle weight is taken as the drive axle load ratio, the internal pressure of the air spring at the rear axle side is almost equal to the drive axle load ratio when the vehicle is empty Is increased in accordance with the increase in the load.

Therefore, according to the present invention, the internal pressure of the air spring on the rear shaft side is increased in accordance with the increase in the load so that the internal pressure of the air spring becomes substantially equal to the drive shaft weight ratio when the vehicle is empty. It is possible to stably control the air pressure of the air spring, to prevent the rear wheel from being brake-locked, to prevent the vehicle from being disturbed, and to eliminate a dangerous state.

[Brief description of the drawings]

FIG. 1 is a side view of a truck including a driving force applying device.

FIG. 2 is a piping diagram illustrating a configuration of a driving force applying device.

FIG. 3 is a graph showing a control operation.

FIG. 4 is a graph showing a control operation.

FIG. 5 is a graph showing a control operation.

[Explanation of symbols]

 Reference Signs List 10 frame 11 cab 12 carrier 14 front wheel 15 rear front wheel 16 rear wheel 17 rear front shaft 18 rear shaft 21 leaf spring 22 air spring 23 leaf spring 24 air spring 28 communication cutoff switching valve 29 first vehicle height adjustment valve 30 second vehicle height Adjusting valve 31 Air tank 32 Exhaust valve 33 Air supply valve 34, 35 Solenoid valve 39, 40 Computer 41 Vehicle height sensor 42 Vehicle speed sensor 45, 46 Pressure sensor

Claims (2)

[Claims] An air spring of a suspension device for suspending a rear shaft consisting of a driven shaft discharges air from the air spring to increase the axle weight of a rear front shaft consisting of a driving shaft to increase the driving force of a driving wheel. The driving force applying device for a two-axle vehicle according to claim 1, wherein the internal pressure of the air spring on the rear axle side in the driving force applied state is gradually increased in accordance with an increase in the load. Driving force adding device. 2. The driving force of a driving wheel is increased by discharging the air from an air spring of a suspension device that suspends a rear shaft composed of a driven shaft to increase the axial load of a rear front shaft composed of a driving shaft. In the driving force adding device for a rear two-axle vehicle, the ratio of the axle weight applied to the rear two axles or the ratio of the axle load applied to the rear front axle composed of the drive shaft to the total weight of the vehicle in the driving force added state is defined as a drive axle weight ratio. The driving force applying device for a rear two-axle vehicle, wherein the internal pressure of the air spring on the rear shaft side is increased in accordance with an increase in the load so as to become substantially equal to the drive shaft weight ratio when the vehicle is empty. .