JPH09109645A - Axle load distributing device of air suspension vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute axle load corresponding to respective traveling modes or carrying load corresponding to the will of a driver, by taking measures for controlling intake and exhaust for each axis on which an air spring is mounted on the basis of the vehicle speed and a plurality of axle loads in response to an on-signal of an axle load distributing switch. SOLUTION: An air tank 1 supplies air to respective pairs of front axes and rear axes square air springs 2f, 2r through an air pipe 3. The compression height of respective air springs 2f, 2r are detected by a height sensor 16. The axle load distribution of respective air springs 2f, 2r is determined by an axle load distributing sensor 5. Pressures of respective air springs 2f, 2r are respectively detected by respective pressure sensors 7, 8 as an axle load detecting means. Air pressures of respective air springs 2f, 2r are adjusted by a control unit 10 on the basis of respective detected signal. That is, respective axle independent solenoid valves 12 interposed in the air pipe 3, respective air supplying solenoid valves 14f, 14r, and respective air discharging solenoid valves 15f, 15r are respectively controlled so as to be opened and closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axle load distribution device for an air suspension vehicle, and more particularly to a technique for changing the axle load distribution of the axle weight of multiple axes such as a tandem axle according to the vehicle weight and vehicle speed.

[0002]

2. Description of the Related Art As shown in FIGS. 7, 8 and 9, a three-axle vehicle having two rear axles normally has a sprung weight supported by two axles, a rear front axle Rf and a rear rear axle Rr. Even if the rear-front shaft rides on protrusions, brakes, accelerates, etc., one shaft does not support the weight but the other shaft supports the weight. That is,
It is constructed so that the suspension of only one shaft does not bear the weight and the ground pressure does not change. Also,
Although not shown, the same applies to suspensions having multiple axes, such as large truck cranes and trailers.

The weight distribution between the rear front shaft Rf and the rear rear shaft Rr is generally equal to 2 (1) (FIG. 8) or from the viewpoint of tire load (FIG. 9). . In a so-called tandem type axle using a conventional leaf spring, the distance between fulcrums is divided by the lever ratio to distribute the weight. On the other hand, in the air spring type suspension, the diaphragm or
The axial load distribution is determined by the pressure receiving area of the bellows and the air pressure.

Axial load distribution for both mechanical and pneumatic systems
Fixed. As a result, the rear front shaft Rf and the rear rear shaft Rr
In the case of an empty vehicle or the like which has a small weight, the weight support becomes extremely thin on a shaft having a small weight distribution. In the case where the rear weighted shaft Rr is the shaft having a small weight distribution, the resistance in the yaw direction is small in terms of running stability, which is not preferable. Further, since the distribution of the braking force is generally adjusted to the distribution of the axial load, there is a concern that the tire may slip due to the lock and the braking force may be reduced or a problem may occur in the maneuverability on the shaft having a small weight support.

A technique for increasing the weight distribution to the drive shaft at the time of starting has been proposed for a large-sized bus, but in this case, the dead shaft is easily locked during braking. In addition, this technology has not yet been developed for stable driving at high speeds. (Japanese Utility Model Publication No. 58-173508, Japanese Utility Model Publication No. 63-5180)
No. 4).

[0006]

In the conventional axial load distribution device for an air suspension vehicle as described above, since the axial load distribution is fixed, for example, the axial load movement to the drive shaft suitable for start acceleration, high speed It was not possible to distribute the axle weight according to each driving mode, such as the axle weight distribution that emphasizes stability during traveling, and the axle weight distribution that considers maneuverability and traveling stability during general medium speed traveling.

An object of the present invention is to provide an axle load distribution device for an air suspension vehicle for obtaining an axle load optimum for such various traveling modes.

[0008]

Therefore, as shown in FIG. 1, the invention according to claim 1 is provided with a multi-axis suspension device comprising an air tank and comprising a plurality of shafts each having an air spring attached thereto. In an air suspension vehicle, an axle load distribution switch that determines whether or not to perform axle weight distribution for each of the multiple axes, vehicle speed detection means that detects the traveling vehicle speed, and axle load detection that detects the axle weight of each of the multiple axes. Means, control means for performing a predetermined air supply or exhaust operation for each axis according to the vehicle speed and the multiple axle weight detected by the detection means by the ON signal of the axle weight distribution switch, and the control means from the control means. A shaft air pressure independent means that separates or connects each axis of the multi-axis in the air pressure circuit by a signal, and an air supply means that supplies compressed air in the air tank to each axis air spring by a signal from the control means. , The above An exhaust pressure reducing means for evacuating vacuum from the shaft air spring by a signal from the control means, and configured to include.

According to a second aspect of the present invention, in an air suspension vehicle including an air tank and a multi-axle suspension device composed of a plurality of shafts having air springs mounted on the respective shafts, axial load distribution of each of the multi-axes is performed. Axle load distribution switch for determining whether or not, vehicle speed detection means for detecting the traveling vehicle speed, axis load detection means for detecting the axis load of each axis of the multiple axes, and the detection means by the ON signal of the axis load distribution switch. In accordance with the vehicle speed and the multi-axle load detected by the above, a predetermined air supply or exhaust operation for each axis, and a control means for performing an exhaust operation, and the multi-axis each axis is separated or independently in an air pressure circuit by a signal from the control means, or
Each axis air pressure independent means to communicate with each other, air supply means for boosting the compressed air in the air tank to each axis air spring by a signal from the control means, and exhaust air pressure reduction from each axis air spring by a signal from the control means An exhaust pressure reducing means for causing the rear front axle weight to increase at a middle or low speed where the rear front axle is equal to or lower than a predetermined axle weight and the traveling vehicle speed is equal to or lower than a predetermined speed when the axle load distribution switch is ON. The weight distribution is changed so that the rear axle weight is reduced.

According to a third aspect of the present invention, when the axle load distribution switch is in the ON state, the rear front axle has a predetermined axle load or less and the traveling vehicle speed is less than a predetermined low speed, the rear front axle has a sprung mass weight up to the axle weight limit. I took charge of everything.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the configuration of the rear two-axis tandem axis air suspension will be described with reference to FIG.
In addition, for the suspension with 3 or more rear axles used for large cranes and trailers, for ease of explanation,
It will be described after the description of the rear two-axis tandem suspension in which the configuration and the operating procedure are essentially the same.

In FIG. 2, in the suspension, the rear front shaft is a drive shaft, the rear rear shaft is a dead shaft, and the permissible axial loads are the same. Diaphragm type air springs 2f, 2f,
An air tank 1 for supplying compressed air to 2r and 2r is supplied with air from a compressor (not shown). Air is supplied from the air tank 1 to the rear and front axle air springs 2f and 2f and the rear and rear axle air springs 2r and 2r through the air pipe 3.

The air springs 2f, 2f and 2r, 2r are
If they have the same area and the same volume and the compression height is constant, the axial load to be supported is determined by the height of the air pressure. A vehicle height sensor 16 for detecting the compression height is provided on each rear rear shaft. As for the axle weights of the rear front axle and the rear rear axle, the axle weight distribution is determined by the weight applied to both axles and the vehicle speed. For example, in normal traveling, the pressure in the air spring is the same so that the axial loads are equally distributed. Further, by a shaft load distribution switch 5 to be described later, most of the weight is supported by the rear front shaft, which is the drive shaft in this case during start-up acceleration, and the weight distribution is slightly offset to the rear front shaft during medium and low speed traveling. .

The driver's seat is provided with a shaft load distribution switch 5 for determining whether or not to perform a functional operation capable of distributing the shaft load. Then, a vehicle speed sensor 6 as a vehicle speed detecting means for detecting a vehicle speed, which is one factor for determining the axial load distribution, takes out rotation information from a transmission (not shown) and inputs it to a control unit 10 which will be described later.

Similarly, as the axial load detecting means for detecting axial load, which is another factor for determining the axial load distribution, the air spring pressure of the rear and front axles is a pressure sensor 7p, and the air spring pressure of the rear and rear axles is a pressure sensor. 8f, the pressure information is taken out and the signal is inputted to the control unit 10. The control unit 10 is a signal processing and transmitting device incorporating a microcomputer or the like, which inputs the axle load distribution switch ON signal, the vehicle speed signal, the axle weight signal, and the like, and the rear front axle and the rear rear axle load are predetermined. The air pressure adjustment of the air springs 2f, 2f, 2r, 2r for supporting the weight is instructed to be transmitted. Further, the air tank 1 is confirmed by the signal of the pressure sensor 1a.

In addition, in order to separate and independently provide the rear front shaft and the rear rear shaft between the rear and front shaft air springs 2f and 2f and the rear and rear shaft air springs 2r and 2r with respect to the air supply. Each axis independent solenoid valve 12 is interposed. Further, an air supply solenoid valve 14f for supplying and boosting air to the front and rear axle air springs 2f, 2r to the air pipe 3, respectively.
14r (hereinafter, generically referred to as 14) Air exhaust electromagnetic valves 15f and 15r (hereinafter, generically referred to as 14) for exhausting and decompressing air are provided.

The shaft independent solenoid valve 12, the air supply solenoid valve 14 and the air discharge solenoid valve 15 are operated by an instruction signal from the control unit 10. Next, the operation will be described. In the flowchart of FIG. 3, a step of determining the traveling conditions and the axle load distribution of the vehicle speed and the tandem axle weight determined by the load amount (S in the figure).
It is written. The same shall apply hereinafter).

Step 1 is a normal axle load distribution, that is, the axle weights of the rear front axle and the rear axle are always equal, and the running condition in this state is called mode NOR. In this mode NOR, the air pressures of the rear and front axle air springs 2f and 2f and the rear and rear axle air springs 2r and 2r are the same as in the conventional tandem suspension. Therefore, each axis independent solenoid valve 12 is in an open state such that the air pipe 3 communicates with the front and rear.

Next, in step 2, the control unit 10 determines whether or not the axial load distribution switch 5 is ON. If the driver is willing to change the axial load distribution depending on the traveling conditions, the axial load distribution is changed according to the traveling speed by the instruction signal from the controller 10. Also, the axial load distribution switch 5 is turned off.
If this is the case, the axle load distribution will always be even and the driving conditions will be mode NO.
It becomes R.

In step 3, it is judged whether the rear front shaft, which is the drive shaft in this case, is within the allowable limit of the axial load, for example, within 9.5 tons, and the axial load can be increased. That is, the change of the axial load distribution always increases the axial load of the drive shaft, in this case, the front and rear shafts, so that it is confirmed that it is within the allowable value of 9.5 tons, for example. If the weight is 9.5 tons or more, the axle load will be divided equally and the mode will be NORMAL.

In step 4, it is determined whether the vehicle speed is a high speed running at a predetermined speed (for example, 60 km / h) or more.
When the vehicle speed is 60 km / h or more, step 5 is performed, the axle load is equally divided, and the mode is NOR. In step 6, the vehicle speed is a predetermined speed (for example,
When the speed is 60 Km / h or less, the distribution of the axle weight of the rear and front axles is slightly increased so that the braking force of the rear and rear axles does not decrease so much and the driving force is increased to improve maneuverability. The traveling in this case is referred to as mode 1.

The axial load distribution has a characteristic diagram as shown in FIG. In the figure, A is a line indicating the front and rear axle loads, and B is a line indicating the rear and rear axle loads. Describing this diagram with a mathematical formula, the front and rear axle weight W after distribution
If F is less than 9.5 tons of allowable axle load, front and rear axle weight WF (ton)
= ((Wf + Wr) / 2) × constant ratio (for example, 1.2)
5), rear rear axle load WR (ton) = ((Wf + Wr) / 2)
× It becomes a fixed ratio (for example, 0.75). Here, Wf (ton) is the front-rear axle load before the distribution change, and Wr (ton) is the rear-rear axle load before the distribution change. Also, (Wf +
Wr) is a multiaxial load. Further, in this example, Wf = Wr
But also. Further, when the WF reaches the limit axial load of 9.5 tons, the axial load of the WR is WR (ton) = (Wf + Wr) −
It is 9/5.

As described above, the axial load is determined for the traveling conditions of the mode NOR and the mode 1, but the device operates as follows. In the mode NOR of step 1, for example, the rear and front axle air springs 2f and 2f and the rear and rear axle air springs 2r and 2r are filled with air at 6 kg / cm ² , for example. Since the front and rear have the same pressure, the solenoid valve 12 for each axis is open and the air pipe 3
The front and back communicate. The compressed air guided from the air tank 1 is supplied to the air springs 2f, 2f, 2r, 2r for the front and rear axles via the solenoid valves 14f, 14r for air supply. At this time, solenoid valves 15f and 15r for air discharge
Is closed and not open to the atmosphere. When the vehicle height sensor 16 confirms a predetermined compression height at a predetermined 6 kg / ccm ² by the rear front and rear rear air spring pressure sensors 7 and 8, the air supply solenoid valves 14f and 14r are closed. The suspension function is activated.

Next, in step 2, the driver manually decides whether to turn on the axial load distribution switch or keep it off. In step 3, it is determined whether the rear front axle load exceeds 9.5 tons from the pressure indicated by the rear front axle air spring pressure sensor 7. In step 4, the vehicle speed sensor 5 detects the rotation of the output shaft of the transmission, calculates the vehicle speed based on the signal, and determines whether or not the speed is equal to or higher than a predetermined speed (for example, 60 Km / h), and then proceeds to step 5 or 6. Branch decision and switching are performed.

In step 5, the mode NOR travel instruction is switched at the above-mentioned predetermined speed (for example, 60 km / h) or more. In step 6, since the mode 1 traveling is performed, the weight of the rear front axle, which is the drive shaft, is increased in the following manner. First, the solenoid valves 12 for independent axes are closed to separate the air piping 3 into the front and rear axles and the rear and rear axles. Next, the rear rear axle air spring 2r,
The rear rear axle air discharge solenoid valve 15r connected to 2r is opened to reduce the pressure of the rear rear axle air springs 2r, 2r to reduce the rear rear axle load. With this decrease in axial load, the front and rear axles increase axial load. At this time, in order to adjust the axial load distribution and the vehicle height, the rear-front-shaft air supply solenoid valve 14f is opened to guide the compressed air from the air tank 1 to the rear-front shaft air springs 2f, 2f.

The control unit 10 performs all of the necessary signal collection, calculation, analysis, judgment, operation signal instructions, etc. in the above steps. Next, with reference to the flow chart of FIG. 4, a method of displacing the axle weights on the rear and front axles of the drive shaft, which is effective for starting acceleration, escape from a bad road, etc., will be described. The configuration of the device is the same as that shown in FIG. 2 of the previous embodiment.

The operations of steps 11, 12, and 13 are similar to those of steps 1, 2, and 3 of the previous embodiment. Step 14
Determines whether the vehicle speed is a low speed traveling at a predetermined speed (for example, 10 km / h) or less. If the vehicle speed is equal to or higher than the predetermined speed (for example, 10 km / h), the step 15 is performed. Then, the subsequent steps 15, 17, and 18 are the same operations as the steps 4, 5, and 6 of the previous embodiment.

In step 16, the driving force of the rear front shaft, which is the drive shaft, is increased when the vehicle travels at a low speed below a predetermined speed (for example, 10 km / h). The low speed traveling in this case is referred to as mode 2. The axial load distribution is the characteristic diagram shown in FIG. 6, in which A is a line indicating the front-rear axle load and B is a line indicating the rear-rear axle load. In this way, the front and rear axles have an allowable limit of 9
Up to 5 tons, the rear front axle supports the entire sprung weight.
The rear and front axles support the weight exceeding 9.5 tons with the rear and rear axles. Therefore, when the rear / front axle is 9.5 tons or less, the rear / rear axle weight is only unsprung weight.

In this case, the method of operating the device for distributing the axial load is substantially the same as step 6 of the previous embodiment except that the numerical values are changed. Next, a multi-axle vehicle having three or more rear axles will be described. There are cases where all the rear axles are driven and dead is included. In all cases, a large load is distributed to the specific drive axle.

In such a special heavy vehicle, it is necessary to make the turning radius particularly small. In this case, the axial load distribution is increased on the front drive shaft. In addition, in order to prevent uneven wear of the tire during general driving, the weight of the drive shaft in the central portion is increased. Even in the case of the plurality of axes, the device configuration and the content of the operation are essentially the same as the example of the rear two-axis tandem suspension.

[0031]

As described above, according to the first aspect of the present invention, in an air suspension vehicle equipped with an air tank and a multi-axle suspension device composed of a plurality of shafts with air springs mounted on each shaft, Axle load distribution switch for deciding whether or not to distribute the axial load of each axis, vehicle speed detection means for detecting the traveling vehicle speed, axial load detection means for detecting the axial load of each of the multiple axes, and the axial load Control means for performing a predetermined air supply or exhaust operation for each axis according to the vehicle speed and the multi-axle load detected by the detecting means by the ON signal of the distribution switch, and each axis of the multi-axis by a signal from the control means. Independently or independently of each other in the air pressure circuit, each axis air pressure independent means, and air supply means for supplying compressed air from the air tank to each axis air spring by a signal from the control means.
Exhaust decompression means for decompressing exhaust from each axial air spring in response to a signal from the control means, and
Since the driver can voluntarily set the axle load according to each traveling mode such as start acceleration, general medium / low speed traveling, high speed traveling, etc. and the load, for example, in start acceleration, the axle load of a specific drive shaft can be increased. The driving force is increased to facilitate starting acceleration and escape from bad roads.At medium and low speeds, the load distribution on the front drive shaft is increased a little, and other shafts do not lock during braking. It is possible to improve maneuverability and maneuverability with a certain degree of axle load, prevent tire uneven wear of the rear axle, and evenly divide each axle weight at high speed to improve traveling stability. It was

According to a second aspect of the present invention, there is provided an air suspension vehicle including an tandem shaft suspension device including an air tank, a rear front shaft having air springs mounted on respective shafts, and a rear two shafts of a drive shaft. Axle load distribution switch that distributes the axle weight of each of the front and rear axles and rear and rear axles according to the tandem axle weight, vehicle speed detection means that detects the traveling vehicle speed, and axle weights of the rear front axle and rear rear axle. A shaft load detection means, a control means for performing a predetermined air supply or exhaust operation for each axis by an ON signal of the shaft load distribution switch, and an air pressure for each shaft by a signal from the control means. Independently or independently in the circuit each axis air pressure independent means, air supply means for supplying and boosting compressed air in the air tank to each axis air spring by a signal from the control means, and a signal from the control means Exhaust pressure reducing means for reducing the pressure of the exhaust air from the axial air spring, and when the axle load distribution switch is in the ON state, the rear front axle is at a predetermined axle load or less and the traveling vehicle speed is a predetermined speed or less at a middle or low speed. Since the weight distribution is changed so that the axle load increases and the rear-rear axle weight decreases, the rear-front axle drive and rear-rear axle dead tandem suspension increase the rear-rear axle weight at low and medium speeds. It was heavy and the dead shaft was light to increase the driving force and improve maneuverability. Further, the change of the axial load distribution is convenient because it can be carried out when the driver needs it.

According to the third aspect of the present invention, when the axle load distribution switch according to the first and second aspects is ON, the rear front axle is at a predetermined axle load or less and the traveling vehicle speed is at a predetermined low speed or less. Since it is designed to handle the entire sprung weight up to the axle load limit, at low speeds such as starting acceleration, the rear and front axles support the entire sprung weight up to the axle load allowable limit to obtain the maximum driving force within the vehicle conditions. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an axle load distribution device for an air suspension vehicle according to the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the above.

FIG. 3 is a flowchart illustrating the operation of the above embodiment.

FIG. 4 is a flowchart illustrating another operation of the embodiment of FIG.

FIG. 5 is a diagram showing a relationship between a drive shaft and a dead shaft load when traveling at a medium or low speed.

FIG. 6 is a diagram showing a relationship between a drive shaft and a dead shaft load at the time of starting acceleration.

FIG. 7 is an explanatory diagram showing a tandem shaft.

FIG. 8 is an explanatory diagram showing an example in which tandem shafts have the same axial load.

FIG. 9 is an explanatory diagram showing an example in which the axle weight is set to front 2 and rear 1 with a tandem shaft.

[Explanation of symbols]

 1 Air Tank 2f Rear Front Axis Air Spring 2r Rear Rear Axis Air Spring 3 Air Piping 5 Axle Weight Distribution Switch 6 Vehicle Speed Sensor 7 Rear Front Axis Air Spring Pressure Sensor 8 Rear Front Axis Air Spring Pressure Sensor 10 Control Unit 12 Each Axis Independent Solenoid valve 14f Rear-front-axis air supply solenoid valve 14r Rear-rear-axis air supply solenoid valve 15f Rear-front-axis air discharge solenoid valve 15r Rear-rear-axis air discharge solenoid valve 16 Vehicle height sensor

Claims (3)

[Claims] 1. An air suspension vehicle equipped with an air tank and a multi-axle suspension device comprising a plurality of shafts, each of which is equipped with an air spring, and determines whether or not to perform axial load distribution of each of the multi-axes. Axle load distribution switch, vehicle speed detection means for detecting the traveling vehicle speed, axle load detection means for detecting the axle load of each axis of the multiple axes, vehicle speed detected by the detection means by an ON signal of the axle load distribution switch, and Control means for performing a predetermined air supply or exhaust operation for each axis according to the axis load, and each axis air pressure for separating or communicating each axis of the multi-axis in an air pressure circuit by a signal from the control means. Independent means, air supply means for supplying / compressing compressed air from the air tank to each axial air spring by a signal from the control means, and exhaust air for reducing pressure from each axial air spring by a signal from the control means An axle load distribution device for an air suspension vehicle, comprising: a decompression means. 2. An air suspension vehicle equipped with an tandem shaft suspension device comprising an air tank, an air spring mounted on each shaft, and a rear front shaft composed of two rear shafts of a drive shaft, in accordance with a vehicle speed and a tandem shaft load. Axle load distribution switch that distributes the axial load of each of the front and rear axles and rear and rear axles, vehicle speed detection means that detects the traveling vehicle speed, and axle load detection that detects the axial weight of each of the rear front and rear axles Means, control means for performing a predetermined air supply or exhaust operation for each of the shafts by an ON signal of the shaft load distribution switch, and each of the shafts is separated or independently in an air pressure circuit by a signal from the control means, or Each axis air pressure independent means to communicate with each other, air supply means for supplying compressed air in the air tank to each axis air spring by a signal from the control means, and exhaust from each axis air spring by a signal from the control means The exhaust pressure reducing means for reducing the pressure is included, and when the axle load distribution switch is in the ON state, the rear front axle weight increases when the rear front axle is equal to or lower than a predetermined axle load and the traveling vehicle speed is equal to or lower than a predetermined speed. An axle load distribution device for an air suspension vehicle, wherein the weight distribution is changed so that the rear-rear axle load is reduced. 3. When the axle load distribution switch is in the ON state, the rear front axle is provided with the entire sprung weight up to the axle weight limit when the rear front axle has a predetermined axle load or less and the traveling vehicle speed is a predetermined low speed or less. The axle load distribution device for an air suspension vehicle according to claim 2, wherein