JP3808146B2 - Axle load adjuster - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used for axle load adjustment for distributing the load of an automobile to each axle. The present invention is used in an automobile equipped with an air spring corresponding to an axle. The present invention relates to harmonious control of both systems when both a vehicle height adjustment system and a shaft load adjustment system are installed. The present invention relates to an improvement for harmonizing an apparatus in which both automatic adjustment of vehicle height and automatic adjustment of a shaft load are performed by adjusting the air pressure of an air spring.
[0002]
[Prior art]
The height of a vehicle changes when the displacement of a spring that connects the chassis and the vehicle body varies depending on the load weight or the number of people on the vehicle. For vehicles with a structure in which an air spring is inserted between the chassis and the vehicle body, or in a vehicle with a structure in which an air spring is used in combination with a mechanical spring, the vehicle height is adjusted by changing the internal pressure of the air spring. can do. A technique is known in which a so-called leveling valve is provided to automatically adjust the distance between the chassis and the vehicle body so that the distance is always within a certain range regardless of the loaded weight. Leveling valves are mechanical adjustment systems that open and close mechanical valves by detecting displacement by mechanical detection means, and those that do not perform computer control or electromagnetic valve control are widely used.
[0003]
On the other hand, a device for automatically adjusting the drive shaft load has been used so that the drive shaft wheel does not slip when the vehicle is accelerated. For example, the case where it is used for a large vehicle with two rear wheels is described. The rear wheels are arranged so as to receive the main load of the loaded load, and the front shaft of the two rear wheels is the drive shaft. The rear shaft is a non-drive shaft. A sufficient load is applied to the two shafts when the load is large, but if the vehicle accelerates rapidly when the load is small, the wheels of the drive shaft may slip with respect to the road surface. In order to avoid this, the load on the rear shaft of the two rear wheel shafts is temporarily reduced to increase the load on the front shaft, which is the drive shaft. For this purpose, an air spring is provided for each shaft, and when the shaft load is controlled, the air spring internal pressure of the front shaft is increased and the air spring internal pressure of the rear shaft is controlled low. .
[0004]
[Problems to be solved by the invention]
As described above, the vehicle height automatic adjustment system and the shaft load automatic adjustment system are both provided in one vehicle, and when two automatic adjustment systems perform adjustment operations simultaneously, the two control systems are mutually connected. It is possible that the control does not converge due to interference. In particular, even if each control has converged to the desired target range, when small deviations are detected and alternating fine control is performed, the air pressure enters and leaves the air spring in small increments. The air pressure in the compressed air tank of the vehicle will be lost. The two automatic adjustment systems are both computer-controlled, and when control is performed by one main computer or by mutually transmitting and receiving signals, control disruption may be arbitrated by time division of control or mutual prohibition signals. Although it is conceivable, it has been found that in the present embodiment, the vehicle height adjustment system is a mechanical system control, and the control of the shaft load is often a computer control, which requires some kind of arbitration function.
[0005]
The present invention has been made against such a background, and an object thereof is to provide a control device in which two control systems do not interfere with each other with a simple configuration. An object of the present invention is to provide an apparatus capable of performing control without mutual interference even if one control system is a mechanical system. It is an object of the present invention to provide a control device in which fine adjustment control is frequently repeated so that the amount of air entering and exiting the air spring increases and the air pressure stored in the air tank of the vehicle is not lost. To do.
[0006]
[Means for Solving the Problems]
The present invention is characterized in that the operations of the two control systems of the vehicle height adjustment system and the shaft load adjustment system do not interfere with each other, and the vehicle height automatic adjustment control and the shaft load automatic adjustment control are harmonized.
[0007]
That is, the present invention provides an air spring provided between the vehicle body and a plurality of axles, and first means for controlling the internal pressure of the air spring so that the vehicle height value is within a certain range (vehicle height adjustment). System), means for detecting the air spring internal pressure at least for the drive shaft, and second means for controlling the air spring internal pressure of the drive shaft to be greater than the air spring internal pressure of the driven shaft (shaft load adjustment) In the period when the first means for adjusting the internal pressure adjusts the internal pressure of the air spring, the means for detecting the internal pressure is changed to the second means. It is characterized in that it is provided with means for prohibiting data acquisition. The period during which the internal pressure of the air spring is adjusted includes a period during which the adjustment valve of the air spring is opened by the first means, and the second means includes a computer circuit and is prohibited. The means preferably includes means for temporarily prohibiting control of the computer circuit by interrupt control.
[0008]
Air springs are provided between the vehicle body and the plurality of axles. In the control of the vehicle height adjustment system, the first means controls the internal pressure of the air spring so that the vehicle height value is always within a certain range. In the control of the shaft load adjustment system, the second means takes in the internal pressure of the air spring on the drive shaft side and the internal pressure of the air spring on the driven shaft side, and adjusts the internal pressure of the drive shaft and the driven shaft according to the loaded load. Moderate. That is, when the loaded load is small, the internal pressure of the air spring on the drive shaft side is set to a predetermined value or more and the internal pressure of the air spring on the driven shaft side is set to a predetermined value or less in order to reduce the slip of the wheel with respect to the road surface. Set.
[0009]
The vehicle height adjustment control is performed by mechanical system control, and the axial load control is often performed by computer control. Therefore, the internal pressure of the air spring may be adjusted by the two control systems at the same time. In the present invention, in order to avoid overlapping control by these two control systems, the period when the internal pressure of the air spring is adjusted and the vehicle height is adjusted by the first means, that is, the period when the control valve is open. Prohibits the taking of data from the means for detecting the internal pressure, and gives priority only to the vehicle height adjustment to reduce the speed of the axle load adjustment control.
[0010]
Thereby, the control operation of the two systems of the vehicle height adjustment system and the shaft load adjustment system can be performed at the same time so as not to interfere with each other, and it is possible to avoid a situation where the control does not converge due to this mutual interference. it can. In addition, since it is possible to avoid alternating fine control by detecting small deviations caused by simultaneous control of the two systems, frequent air pressure in and out of the air spring is reduced and the air tank is It is possible to avoid losing the accumulated air pressure.
[0011]
If the computer circuit is included in the second means for adjusting the axle load, the axle load adjustment control is temporarily prohibited by the interrupt control when the vehicle height adjustment control is performed. Avoid controlling the axial load adjustment at the same time.
[0012]
Also includes a vehicle speed sensor, the second means, 0 ≦ v <v ₁ when the vehicle speed sensor output v is the v ₁ to a predetermined speed
And means for detecting an air spring internal pressure of the driven shaft, and the second means includes an air spring internal pressure of the drive shaft and the driven shaft. The air spring internal pressure of the drive shaft is larger than the air spring internal pressure of the driven shaft until the sum of the air spring internal pressure of the driven shaft reaches a _first threshold value (T ₁ ), and the sum is the first threshold value. Means for equally controlling the air spring internal pressure of both shafts when (T ₁ ) is exceeded, and once the sum exceeds the first threshold (T ₁ ), the first threshold (T ₁ ) The air spring internal pressures of both shafts are made equal until they fall below a smaller second threshold (T ₂ <T ₁ ), and when the sum falls below the second threshold (T ₂ ) Spring internal pressure is adjusted to the driven shaft It is desirable and means for controlling larger than A spring pressure.
[0013]
For example, if v ₁ = 0.5 km / h, there is a possibility of slipping to the wheel of the drive shaft when the output v of the vehicle speed sensor falls below 0.5 km / h and almost stops. In the state, the shaft load adjustment control is performed to increase the load applied to the drive shaft and decrease the load applied to the driven shaft.
[0014]
Load sharing between the drive shaft and the driven shaft is performed according to the shaft load control characteristics (see FIG. 4). That is, the air spring internal pressure of the drive shaft and the air spring internal pressure of the driven shaft are detected, and the air spring internal pressure of the drive shaft is used as the driven shaft until the sum of the detected values reaches the first threshold value (T ₁ ). Larger than the air spring internal pressure. When the sum exceeds the first threshold value (T ₁ ), the possibility of slip is reduced, so that the air spring internal pressures of the drive shaft and the driven shaft are made uniform.
[0015]
When the internal pressure of the air spring decreases from a state where the first threshold value (T ₁ ) is exceeded, until the pressure falls below a _second threshold value (T ₂ : T ₂ <T ₁ ) which is smaller than the _first threshold value (T ₁ ). The air spring internal pressures of the drive shaft and the driven shaft are kept uniform, and the air spring internal pressure of the drive shaft is made larger than the air spring internal pressure of the driven shaft when it falls below the second threshold value (T ₂ ).
[0016]
In this way, control is performed by executing the axial load adjustment when the light load state is changed to the heavy load state and the axial load adjustment when the heavy load state is changed to the light load state according to different pressure values. It is possible to clarify the classification and prevent hunting or misjudgment.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
[0018]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
[0019]
(First Example)
FIG. 1 is a diagram showing the configuration of the main part of the first embodiment of the present invention. In this embodiment, one side of the rear wheel biaxial shaft will be described as an example.
[0020]
In the embodiment of the present invention, the drive shaft air spring 4 and the driven shaft air spring 5 provided between the vehicle body 1 and the drive shaft 2 and the driven shaft 3, respectively, and the drive shaft so that the vehicle height value is within a certain range. The first control means 6 of the vehicle height adjusting system for adjusting the internal pressure of the air spring 4 and the driven shaft air spring 5 and the drive shaft side for detecting the internal pressure of the drive shaft air spring 4 and the driven shaft air spring 5 The internal pressures of the drive shaft air spring 4 and the driven shaft air spring 5 are adjusted so that the internal pressure of the pressure sensor 7 and the driven shaft side pressure sensor 8 and the drive shaft air spring 4 is larger than the internal pressure of the driven shaft air spring 5. A second control means 9 of the axial load adjustment system to be controlled is provided.
[0021]
Further, as a feature of the present invention, the second control means 9 includes a computer circuit, and during the period in which the internal pressures of the drive shaft air spring 4 and the driven shaft air spring 5 are adjusted, the drive shaft side pressure sensor 7 and means for prohibiting data acquisition from the driven shaft side pressure sensor 8 include means for temporarily prohibiting control of the computer circuit by interrupt control.
[0022]
A vehicle height adjusting solenoid valve 12 is disposed in a pipe line connecting the air tank 11 to the drive shaft air spring 4 and the driven shaft air spring 5. The period during which the internal pressures of the drive shaft air spring 4 and the driven shaft air spring 5 are adjusted is a period during which the vehicle height adjusting electromagnetic valve 12 is opened by the first control means 6. A communication cutoff relay valve 13 is disposed in a pipe line connecting the drive shaft air spring 4 and the driven shaft air spring 5. This communication cut-off relay valve 13 is connected to the air tank 11 via a conduit via a driven shaft exhaust solenoid valve 14 and a driven shaft exhaust relay valve 15, and the communication cut-off relay valve 13 is turned on / off by a separate line. It is connected to the air tank 11 via a solenoid valve 16. Further, the air tank 11 and the driven shaft air spring 5 are connected to each other via a driven shaft air supply solenoid valve 17 by a pipe line in a different path.
[0023]
The detection output of the vehicle height sensor 18 is input to the first control means 6, and the detection outputs of the vehicle speed sensor 19, the drive shaft side pressure sensor 7 and the driven shaft side pressure sensor 8 are input to the second control means 9. The The vehicle height adjusting solenoid valve 12 is driven in accordance with a control signal from the first control means 6, and the on / off solenoid valve 16 and the driven shaft air supply solenoid valve 17 are in accordance with a control signal sent out by the second control means 9. To drive.
[0024]
Further, the second control means 9 includes means that is effective when the output v of the vehicle speed sensor 19 is 0 ≦ v <v ₁ when the predetermined speed is v _1. Therefore, the internal pressure of the drive shaft air spring 4 is increased until the sum of the internal pressure of the drive shaft air spring 4 and the internal pressure of the driven shaft air spring 5 reaches the first threshold value T _1. greater than the internal pressure of, and means and, the sum is once a first threshold to control equal the internal pressure of the drive shaft air spring 4 and the driven shaft air spring 5 when the sum thereof exceeds the first to thresholds T ₁ when exceeds T _1, the first thresholds T ₁ less than T ₂ equal to the internal pressure of the drive shaft air spring 4 and the driven shaft air spring 5 to below, and the sum thereof is below a second threshold T ₂ When drive shaft The internal pressure of A spring 4 includes means be greater than the internal pressure of the driven shaft the air spring 5.
[0025]
Next, the control operation in the first embodiment of the present invention configured as described above will be described. In the present embodiment, the rear wheel biaxial will be described, and a leaf spring is mounted on the front wheel, and is omitted here.
[0026]
First, the vehicle height adjustment control operation by the first control means 6 will be described. FIG. 2 is a flowchart showing the flow of the vehicle height adjustment control operation in the first embodiment of the present invention.
[0027]
The first control means 6 takes in the detection output from the vehicle height sensor 18 and determines whether or not the vehicle height is within a normal range. If the vehicle height is not within the normal range, a vehicle height adjustment execution signal is sent to the second control means 9 to perform vehicle height adjustment control. Next, the detection output from the vehicle height sensor 18 is taken to determine whether or not the vehicle height is within the normal range. If the vehicle height is adjusted to the normal range, a vehicle height adjustment execution signal is sent to the second control means 9. To stop.
[0028]
Here, the vehicle height adjustment control operation will be described with reference to FIG. When the vehicle height is below the normal range, the vehicle height adjusting electromagnetic valve 12 is driven to connect the air supply valve 12a and the exhaust valve 12b to the pipeline. At this time, since the communication cutoff relay valve 13 is in a communication state, the air pressure of the air tank 11 is supplied to the drive shaft air spring 4 and the driven shaft air spring 5 and the vehicle height increases. When the vehicle height sensor 18 indicates that the vehicle height has risen to the normal range, the air supply valve 12a of the vehicle height adjusting electromagnetic valve 12 is driven to shut off the air supply line. As a result, the supply of air pressure from the air tank 11 to the drive shaft air spring 4 and the driven shaft air spring 5 is stopped.
[0029]
When the vehicle height exceeds the normal range, the exhaust valve 12b of the vehicle height adjusting solenoid valve 12 is moved to the exhaust position, and the air pressure in the drive shaft air spring 4 and the driven shaft air spring 5 is discharged. When the vehicle height sensor 18 indicates that the vehicle height has fallen within the normal range, the exhaust valve 12a of the vehicle height adjusting electromagnetic valve 12 is moved to the exhaust stop position.
[0030]
Next, a normal axial load adjustment control operation by the second control means 9 will be described. FIG. 3 is a flowchart showing the flow of the axial load adjustment control operation in the first embodiment of the present invention.
[0031]
The second control means 9 takes in the detection output from the vehicle speed sensor 19 and determines whether or not the vehicle speed v is substantially stopped at a speed of 0.5 km / h or less. When the vehicle speed v exceeds 0.5 km / h, the vehicle weight does not change, so that the axle load determination is not performed. When the vehicle speed v indicates 0.5 km / h or less, the wheel of the drive shaft 2 may slip, so the output of the drive shaft side pressure sensor 7 and the output of the driven shaft side pressure sensor 8 are taken in. The sum T of the internal pressure P1 of the air spring 4 and the internal pressure P2 of the driven shaft air spring 5 is calculated.
[0032]
FIG. 4 is a diagram showing the axial load adjustment control characteristics in the first embodiment of the present invention. Second control means 9 judges whether or not the calculated sum T exceeds the thresholds T ₁ in FIG. If the sum T exceeds the threshold value T ₁ , it is assumed that there is a heavy load state, and the wheels on the drive shaft 2 are less likely to slip, so the load applied to the drive shaft 2 and the driven shaft 3 is maintained in a uniform state. . When the sum T is equal to or less than the threshold value T ₁ , the shaft load adjustment is executed to increase the load applied to the drive shaft 2.
[0033]
That is, the second control means 9 determines the internal pressure of the drive shaft air spring 4 until the sum T of the internal pressure of the drive shaft air spring 4 and the internal pressure of the driven shaft air spring 5 reaches the first threshold value T _1. was greater than the internal pressure of the driven shaft the air spring 5, and an equal internal pressure of the drive shaft air spring 4 and the driven shaft air spring 5 when the sum T exceeds the first threshold T _1. Once the sum T exceeds the first threshold value T ₁ , the drive shaft air spring 4 and the driven shaft air spring 4 fall below a _second threshold value T ₂ (T ₂ <T ₁ ) that is smaller than the _first threshold value T ₁ . When the internal pressure of the spring 5 is made equal and the sum T falls below the second threshold T ₂ , the internal pressure of the drive shaft air spring 4 is made larger than the internal pressure of the driven shaft air spring 5.
[0034]
Here, the axial load adjustment control operation will be described in detail with reference to FIG. The solid line in the figure indicates a state in which the axle load is shared by the drive shaft 2 and the driven shaft 3, the solid line arrow indicates the control path from the light load state to the heavy load state, and the broken line arrow indicates from the heavy load state The control path to the light load state is shown. In this embodiment, it is assumed that the heavy load state is when the total axle weight is greater than W _1, and the light load state is when the load is smaller than W ₁ . In the light load range, the relationship between the total axle weight and the axle weight shared by the drive shaft 2 and the driven shaft 3 is to increase the axle weight shared by the drive shaft 2 as the axle weight increases. The internal pressure of the air spring 4 is increased to a mechanically safe limit value T ₃ .
[0035]
If the axle load is further increased, maintaining the internal pressure of the drive shaft air springs 4 to the limit value T _3, the increase is driven axis air spring 5 share. When the sum T of the internal pressures of the air springs supporting the entire axle weight reaches the first threshold value T ₁ , the wheels slip even if the weight applied to the drive shaft air spring 4 is not increased. Since the possibility is small, the shaft weight shared by the drive shaft air spring 4 and the driven shaft air spring 5 is made uniform.
[0036]
When shifting from the heavy load state to the light load state, the drive shaft air spring 4 and the driven shaft air spring 5 apply uniform loads until hysteresis is provided and the total shaft weight becomes W ₂ smaller than W _1. to share the load. When the total shaft weight reaches W ₂ , the load on the drive shaft air spring 4 is increased, and the load on the driven shaft air spring 5 is reduced.
[0037]
In this way, with a hysteresis, the threshold value for the start point of the axial load adjustment when shifting from the light load state to the heavy load state is different from the start point of the shaft load adjustment when shifting from the heavy load state to the light load state. By setting in step, it is avoided that the control classification becomes clear and erroneous control is performed.
[0038]
Next, the axial load adjustment operation performed by the control of the second control means 9 will be described with reference to FIG.
[0039]
When it is determined that the second control means 9 is in a light load state, in order to increase the load applied to the drive shaft 2, the on / off solenoid valve 16 is turned on to cut off the air pressure of the air tank 11. Supply to relay valve 13. By supplying the air pressure, the communication cutoff relay valve 13 is operated to connect the conduit communicating with the driven shaft exhaust relay valve 15 and the driven shaft air spring 5.
[0040]
At the same time, the driven shaft exhaust electromagnetic valve 14 is driven to supply the air pressure of the air tank 11 to the driven shaft exhaust relay valve 15. The driven shaft exhaust relay valve 15 which has received this air pressure connects the discharge port and the communication cutoff valve 13 and discharges the air in the driven shaft air spring 5 from the discharge port.
[0041]
The second control means 9 monitors the pressure drop by the detection output of the driven shaft side pressure sensor 8 during the air discharge process, and drives the driven shaft exhaust electromagnetic valve 14 when the pressure value drops to a predetermined value. Then, the supply of air pressure to the driven shaft exhaust relay valve 15 is stopped. By stopping the supply of air pressure, the driven shaft exhaust relay valve 15 blocks the passage between the conduit from the communication cutoff relay valve 13 and the discharge port of the driven shaft exhaust relay valve 15 and discharges air from the driven shaft air spring 5. Stop. As a result, the air pressure of the drive shaft air spring 4 becomes higher than the air pressure of the driven shaft air spring 5, and the load shared by the drive shaft 2 is increased and the load shared by the driven shaft 3 is decreased.
[0042]
When releasing, the driving of the on / off solenoid valve 16 is stopped, and the air supplied to the communication cutoff relay valve 13 is removed. This communication cut-off relay valve 13 from which air has been removed allows the drive shaft air spring 4 and the driven shaft air spring 5 to communicate with each other, and makes the air pressure of the drive shaft air spring 4 and the driven shaft air spring 5 uniform. As a result, an equal load is applied to the drive shaft 2 and the driven shaft 3.
[0043]
FIG. 5 is a flowchart showing the flow of the interrupt control operation by the second control means in the first embodiment of the present invention.
[0044]
When an interrupt input is received from the first control means 6 by the vehicle height adjustment execution signal during execution of the above-described shaft load adjustment control, the second control means 9 causes the drive shaft side pressure sensor 7 and the driven shaft side pressure sensor to The detection output from 8 is prohibited, and the adjustment speed is lowered until the interrupt signal is released in the shaft load adjustment control. During this axial load adjustment control operation, the second control means 9 monitors the interrupt signal sending state from the first control means 6 and resumes the axial load control when the interrupt signal is released.
[0045]
As described above, when the vehicle height adjustment is performed, the shaft load adjustment is prohibited, so that duplication and confusion of control operations are avoided, and hunting due to the entry and exit of air pressure is prevented, and erroneous determination due to this hunting is performed. Is avoided.
[0046]
(Second embodiment)
FIG. 6 is a diagram showing the configuration of the main part of the second embodiment of the present invention. The second embodiment of the present invention is provided with a leveling valve 21 which is a mechanical control means instead of the vehicle height adjusting solenoid valve of the first embodiment, and the second control is performed from the leveling sensor 22 during the vehicle height adjustment. A vehicle height adjustment execution signal is sent to the means 9. The second control means 9 prohibits the detection output from the drive shaft side pressure sensor 7 and the driven shaft side pressure sensor 8 according to the vehicle height adjustment execution signal, and stops the shaft load adjustment control. Other configurations and operations are the same as those in the first embodiment.
[0047]
【The invention's effect】
As described above, according to the present invention, it is possible to perform harmonious control by eliminating mutual interference between the two control systems of the vehicle height adjustment system and the axial load adjustment system. As a result, the adjustment control by the two control systems is not performed at the same time and frequently, so that air does not enter and exit from the air spring, and the air pressure stored in the air tank can be prevented from losing. .
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of a first embodiment of the present invention.
FIG. 2 is a flowchart showing a flow of a vehicle height adjustment control operation in the first embodiment of the present invention.
FIG. 3 is a flowchart showing a flow of an axial load adjustment control operation in the first embodiment of the present invention.
FIG. 4 is a diagram showing hysteresis control characteristics of shaft load adjustment control in the first embodiment of the present invention.
FIG. 5 is a flowchart showing the flow of an interrupt control operation in the first embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of a main part of a second embodiment of the present invention.
[Explanation of symbols]
1 Car body 2 Drive shaft 3 Drive shaft 4 Drive shaft air spring 5 Drive shaft air spring 6 First control means 7 Drive shaft side pressure sensor 8 Drive shaft side pressure sensor 9 Second control means 11 Air tank 12 Vehicle height Control solenoid valve 12a Air supply valve 12b Exhaust valve 13 Communication cutoff relay valve 14 Drive shaft exhaust solenoid valve 15 Drive shaft exhaust relay valve 16 On / off solenoid valve 17 Drive shaft supply solenoid valve 18 Vehicle height sensor 19 Vehicle speed sensor 21 Leveling Valve 22 Leveling sensor

Claims (2)

An air spring provided between the vehicle body and a plurality of axles, vehicle height detection means, and air supply / exhaust of the air spring so that the vehicle height value falls within a certain range based on the output of the vehicle height detection means a first means to control the internal pressure of the air spring performs control, means for detecting said air spring pressure for the drive shaft and the driven shaft, the internal pressure of the air springs of the drive shaft and the driven shaft a second hand stage when live load based on the output of the means for detecting is small for feeding exhaust control of the air spring as an air spring pressure of the drive shaft is greater than the air spring pressure of the driven shaft In the axle weight adjusting device with
Equipped with a vehicle speed sensor,
This vehicle speed sensor output v indicates a predetermined speed v ₁ When v ₁ ≦ v, the operation of the second means is prohibited, and when 0 ≦ v <v ₁ , the operation of the second means is enabled.
In the second means, the sum of the air spring internal pressure of the drive shaft and the air spring internal pressure of the driven shaft is a first threshold value (T ₁ ) Until the air spring internal pressure of the drive shaft is larger than the air spring internal pressure of the driven shaft, and the sum is equal to the first threshold value (T _1). ), The means for equally controlling the air spring internal pressures of both shafts, and the sum once the first threshold (T ₁ ) Exceeds the first threshold (T _1). ) Smaller second threshold (T ₂ <T ₁ ), And the sum of the air spring pressures of both shafts is equal to the second threshold value (T _2). And a means for controlling the air spring internal pressure of the drive shaft to be larger than the air spring internal pressure of the driven shaft when the pressure is less than (1) . 2. The axle load adjustment according to claim 1 , wherein the second means includes a computer circuit, and the means for inhibiting the operation of the second means includes means for temporarily inhibiting control of the computer circuit by interrupt control. apparatus.

Images