JP7107742B2 - air suspension controller - Google Patents

Description

The present invention relates to an air suspension control device that controls supply and discharge of air to and from air springs.

Vehicle height is adjusted by an air suspension system in freight vehicles such as trucks. Adjustment of the vehicle height by the air suspension system is performed by an air suspension control device that controls the supply and discharge of air to and from the air springs. For example, in the air suspension control device described in Patent Document 1, when the vehicle height detected when the vehicle is in a stopped state exceeds the upper limit or is below the lower limit for a certain period of time, the vehicle height is used as a reference. Air is supplied and exhausted to return to the vehicle height.

JP-A-10-324131

By the way, in a freight vehicle, the weight of the loading platform changes during cargo handling work. Such a change in weight becomes more pronounced, for example, when a vehicle-type material handling machine such as a forklift performs cargo handling work while getting on and off the loading platform. Therefore, in the air suspension control device described in Patent Document 1, there is a possibility that the vehicle height adjustment is performed each time the cargo handling and transporting machine gets on and off. If the vehicle height is adjusted each time the cargo handling and transporting machine is mounted and dismounted, the amount of air consumed increases, and eventually the air stored in the air tank is used up, making it difficult to adjust the vehicle height.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an air suspension control device capable of suppressing air consumption in vehicle height adjustment during cargo handling work.

An air suspension control device that solves the above problems is an air suspension control device that constitutes an air suspension system that is mounted on a vehicle that is equipped with a loading platform into which a material handling and transporting machine can enter, wherein the air suspension system includes an air spring. and an air supply/discharge device for supplying/discharging air to/from the air spring, wherein the air suspension control device includes a key state obtaining unit for obtaining a key state, which is the state of a start key, and a vehicle height of the vehicle. and a vehicle height acquisition unit that controls the air supply and discharge device to adjust the vehicle height to the target vehicle height when the deviation between the vehicle height and the target vehicle height continues for a set time. wherein the set time when the key state is in the OFF state is the average time of cargo handling work by the cargo handling and transporting machine on the loading platform.
According to the above configuration, cargo handling work is performed in the key-off state, so that air consumption associated with vehicle height adjustment can be suppressed even in cargo handling work using a cargo handling and transporting machine.

The air suspension control device includes an operation signal acquisition unit that acquires an operation signal from an operation unit operated by a driver, and a target setting unit that sets the target vehicle height through the operation signal acquired by the operation signal acquisition unit. The operation unit has a start button for changing the vehicle height and a stop button for stopping the change in the vehicle height, and the target setting unit determines the vehicle height when the stop button is operated. It is preferable to set the target vehicle height.

According to the above configuration, since the driver can set the target vehicle height, it is possible to set the target vehicle height in accordance with the height of the platform of the vehicle berth, for example. Further, for example, when the driver outside the vehicle adjusts the vehicle height while visually recognizing the positional relationship between the platform and the cargo bed, the vehicle height at the time of completion of the adjustment can be set as the target vehicle height.

In the air suspension control device described above, it is preferable that the set time is set to a time within a range of 1 minute or more and 5 minutes or less. Further, in the above air suspension control device, it is preferable that the set time is set to a time within a range of 3 minutes±30 seconds.

By setting the set time as in the above configuration, it is possible to secure a sufficient working time for the material handling and transporting machine inside the loading platform even in a cargo handling operation in which the material handling and transporting machine gets on and off the loading platform.

The air suspension control device configured as described above further includes a vehicle speed acquisition unit for acquiring the vehicle speed of the vehicle, and the set time when the vehicle speed is 0 and the key state is on is the first set time. Preferably, the set time when the key state is in the off state is the second set time, and the first set time is the time during which hunting does not occur in supplying and discharging air to and from the air spring.
According to the above configuration, in the key-on state, it is possible to prevent hunting in the supply and discharge of air.

(a) A diagram schematically showing a cargo handling operation using a cargo handling machine for an example of a truck equipped with an air suspension system, (b) an air suspension corresponding to the front and rear wheels. The side view which shows schematic structure of one Embodiment of a system. 1 is a functional block diagram showing a schematic configuration of an air suspension system; FIG. 4 is a flowchart showing an example of a first vehicle height adjustment process; 8 is a flowchart showing an example of a second vehicle height adjustment process;

An embodiment of an air suspension control device and an air suspension system will be described with reference to FIGS. 1 to 4. FIG.
As shown in FIG. 1(a), a vehicle 10 equipped with an air suspension control device and an air suspension system is a truck equipped with a cab 11 in which a driver's seat is installed and a loading platform 12 on which various kinds of luggage are loaded. be. In such a vehicle 10, for example, when the vehicle 10 is in contact with the vehicle berth 13, after the vehicle height is adjusted to the height of the platform 14, a vehicle-type cargo handling and transporting machine 15 such as a forklift moves back and forth between the loading platform 12 and the platform 14. Cargo handling work is carried out while Ride height is adjusted by an air suspension system. The vehicle 10 includes an air suspension system corresponding to the front wheels 16 and an air suspension system corresponding to each of the rear front wheels 17 and the rear rear wheels 18 .

As shown in FIG. 1B, the air suspension system 30 includes an air spring 31 and an air supply/discharge device 32 for supplying/discharging air to/from the air spring 31 . The air spring 31 is arranged between the body frame 19 and the lower plate 20, and maintains the height of the vehicle 10 by maintaining the distance between the body frame 19 and the axle 21, and absorbs the load due to an impact or the like. Absorb. The air suspension system 30 also includes a shock absorber 33 that dampens vibrations of the vehicle. The shock absorber 33 has a cylinder 34 filled with oil, for example, and a piston rod 35 axially movable within the cylinder 34 .

As shown in FIG. 2, the air supply/discharge device 32 for supplying/discharging air to/from the air spring 31 includes a compressor 41, an air tank 42, a leveling valve 43, and an air supply/discharge path connecting the air tank 42 and the air spring 31. 44.

The compressor 41 operates using, for example, an engine or a battery as a power source, compresses air in the atmosphere, and supplies the compressed air to the air tank 42 . The air tank 42 stores air compressed by the compressor 41 . The leveling valve 43 is arranged in the air supply/discharge path 44 to supply/discharge air to/from the air spring 31 . For example, the leveling valve 43 increases the vehicle height by supplying compressed air from the air tank 42 to the air spring 31 in a supply state in which the air tank 42 and the air spring 31 are communicated with each other. The leveling valve 43 reduces the vehicle height by discharging compressed air from the air spring 31 in a discharging state in which the air spring 31 and the atmosphere are communicated.

As shown in FIG. 2, the air suspension system 30 includes a control device 45 as an air suspension control device that controls the supply and discharge of air to and from the air springs through the air supply and discharge device 32 . The air suspension system 30 also includes a key state detector 46 , a vehicle height detector 47 , a vehicle speed detector 48 and a controller 49 .
The control device 45 controls the vehicle height by controlling the leveling valve 43 based on various information. The control device 45 may include a microcomputer and/or dedicated hardware (application-specific integrated circuit: ASIC) that performs at least part of the various types of processing. That is, the control device 45 is configured as a circuit including one or more processors (microcomputers) that operate according to a computer program (software), one or more dedicated hardware circuits such as ASICs, or combinations thereof. be able to. Specifically, in the control device 45, a processor, a memory, an input interface, an output interface, etc. are connected to each other via a bus.

The control device 45 acquires various information output by the various detection units 46 to 48 and the controller 49 via the input interface. The control device 45 executes various processes based on the acquired various information, programs and various data stored in the memory, and controls the leveling valve 43 through these various processes.

A key state detection unit 46 detects the state of a start key that is operated when starting or stopping a power source of the vehicle 10 such as an engine or a motor. The key state detector 46 detects the state after the change when the state of the start key changes, and outputs a signal indicating the detected state to the control device 45 . The states of the start key are the on state in which the power source of the vehicle 10 can be driven and power can be supplied to electrical components, and the accessory in which power can be supplied to electrical components even if the power source is not driven. An activated state (hereinafter referred to as an ACC state) and an OFF state in which both the power supply and electrical equipment are stopped. Note that the start key is not limited to the type in which the key is inserted into a key cylinder and rotated, and includes the type in which a push button is pressed.

The vehicle height detector 47 detects the vehicle height at a predetermined control cycle by measuring, for example, the distance between the body frame 19 and the lower plate 20 . The vehicle height detector 47 outputs a signal indicating the detected vehicle height to the control device 45 . The vehicle speed detection unit 48 detects the vehicle speed v at a predetermined control cycle, for example, by measuring the number of revolutions of an axle that drives the drive wheels. The vehicle speed detector 48 outputs a signal indicating the detected vehicle speed v to the control device 45 .

The controller 49 is a remote controller and functions as an operating unit that can be operated by the driver. The controller 49 has a rise button 50 for starting the supply of air to the air spring 31, a fall button 51 for starting the discharge of air from the air spring 31, and a stop button 52 for stopping the supply or discharge of these. have. The up button 50 and the down button 51 are start buttons to change the vehicle, and the stop button 52 is a stop button to stop changing the vehicle height. The controller 49 outputs operation signals to the control device 45 according to the operation of these various buttons 50 , 51 , 52 . For example, the controller 49 outputs an up signal when the up button 50 is operated, and outputs a down signal when the down button 51 is operated. Also, for example, the controller 49 outputs a stop signal when the stop button 52 is operated.

The control device 45 includes an acquisition section 55, a valve control section 57, a target setting section 58, a timer section 59, and the like as various functional sections that function by executing programs.
The acquisition unit 55 acquires the state of the start key by acquiring the signal output by the key state detection unit 46 as a key state acquisition unit. The acquisition unit 55 acquires the current vehicle height by acquiring the signal output by the vehicle height detection unit 47 as a vehicle height acquisition unit. The acquisition unit 55 acquires the operation content of the controller 49 by the driver by acquiring the signal output by the controller 49 as an operation signal acquisition unit. The acquisition unit 55 acquires the vehicle speed v by acquiring the signal output by the vehicle speed detection unit 48 as a vehicle speed acquisition unit. The valve control unit 57 controls the supply and discharge of air to and from the air spring 31 by controlling the leveling valve 43 . The valve control unit 57 controls opening and closing of the leveling valve 43 in response to, for example, an operation signal from the controller 49 .

The target setting unit 58 sets a target vehicle height, which is a target vehicle height of the vehicle 10 . The target setting unit 58 sets the vehicle height immediately after the vehicle height is adjusted by the operation of the controller 49 as the target vehicle height. In other words, the target setting unit 58 sets the vehicle height acquired by the acquisition unit 55 when the stop signal is input from the controller 49 as the target vehicle height.

The timing unit 59 measures the duration of a state in which the deviation ΔH (=|target vehicle height−vehicle height|) between the vehicle height acquired by the acquisition unit 55 and the target vehicle height set by the target setting unit 58 is equal to or greater than a threshold value ΔHth. A certain divergence time T is measured. For example, the timer 59 is a timer that measures the time from when the divergence ΔH reaches the threshold ΔHth to when the divergence ΔH falls below the threshold ΔHth as the divergence time T. Further, for example, the timer 59 is a counter that counts up at a predetermined cycle, and counts as the deviation time T the count value from when the deviation ΔH reaches the threshold ΔHth to when the deviation ΔH falls below the threshold ΔHth. Further, the clocking unit 59 clocks the elapsed time Tp, which is the time after the acquisition unit 55 acquires the key-off state, by using the above-described timer function, counter function, or the like.

The control device 45 executes vehicle height adjustment processing for automatically adjusting the vehicle height to the target vehicle height when the vehicle 10 is in a stopped state (vehicle speed v=0). The control device 45 repeatedly executes the first vehicle height adjustment process when the key state acquired by the acquisition unit 55 is the ON state or the ACC state. Further, when the key state acquired by the acquisition unit 55 becomes the OFF state, the control device 45 resets the deviation time T of the clock unit 59 and then starts the second vehicle height adjustment process.

An example of the first vehicle height adjustment process will be described with reference to FIG.
As shown in FIG. 3, in the first vehicle height adjustment process, the control device 45 first determines whether the deviation ΔH of the actual vehicle height from the target vehicle height is equal to or greater than a threshold value ΔHth (step S101). If the divergence ΔH is less than the threshold ΔHth (step S101: NO), the control device 45 once terminates the series of processes. On the other hand, if the deviation ΔH is equal to or greater than the threshold ΔHth (step S101: YES), the control device 45 starts timing the deviation time T by the timer 59 (step S102).

Next, the control device 45 acquires the vehicle height again, calculates the difference ΔH, and determines whether the calculated difference ΔH is equal to or greater than the threshold value ΔHth (step S103). If the difference ΔH is greater than or equal to the threshold ΔHth (step S103: YES), the control device 45 determines whether or not the difference time T measured by the timer 59 has reached the first set time T1 (step S104). ). If the deviation time T has reached the first set time T1 (step S104: YES), the control device 45 executes vehicle height adjustment control (step S105).

The first set time T1 is a time applied to a key-on state in which the vehicle 10 is stopped and power can be supplied to the compressor 41 . The key-on state is a state in which the power source of the vehicle 10 is being driven, and the possibility of air shortage in the air tank 42 is low. Therefore, the first set time T1 is preferably a time during which hunting does not occur when air is supplied to and discharged from the air spring 31, that is, a time during which air is not supplied or discharged due to an instantaneous change in vehicle height. From this point of view, it is preferable that the first set time T1 is a short time in seconds as a time during which hunting does not occur. The first set time T1 is, for example, a time of about several seconds, and is selected from a time within a range of 2 seconds±1 second according to the specifications of the air suspension system 30, particularly the specifications of the air supply and discharge device 32. is preferred. It is more preferable that the first set time T1 is two seconds in order to suppress hunting and adjust the vehicle height at an appropriate frequency.

The vehicle height adjustment control in step S105 is control for automatically adjusting the vehicle height to the target vehicle height. In the vehicle height adjustment control, the control device 45 controls the leveling valve 43 so that the vehicle height becomes the target vehicle height. That is, when the deviation ΔH is equal to or greater than the threshold value ΔHth for the first set time T1, the control device 45 controls opening and closing of the leveling valve 43 to control the vehicle height to the target vehicle height. At this time, when the vehicle height is lower than the target vehicle height, the control device 45 supplies the air in the air tank 42 to the air spring 31 to increase the vehicle height. On the other hand, when the vehicle height is higher than the target vehicle height, the control device 45 reduces the vehicle height by discharging the air in the air springs 31 into the atmosphere. When the vehicle height is adjusted to the target vehicle height, the control device 45 resets the divergence time T of the timer 59 in step S106 (step S106), and once ends the series of processes.

On the other hand, if the deviation time T has not reached the first set time T1 (step S104: NO), the control device 45 returns to the process of step S103 and again determines whether the deviation ΔH exceeds the threshold value ΔHth. do. If the deviation ΔH is smaller than the threshold ΔHth (step S103: NO), that is, if the deviation ΔH that was equal to or greater than the threshold ΔHth becomes smaller than the threshold ΔHth, the control device 45 does not perform the vehicle adjustment control in step S105. The difference time T of the clock unit 59 is reset (step S106), and the series of processes is once terminated.

When the state of the vehicle 10 shifts from the stopped state (vehicle speed v=0) to the running state (vehicle speed v≠0), the control device 45 resets the deviation time T of the timer 59 and then performs the first vehicle height adjustment. The processing is ended, and the traveling vehicle height adjustment processing for automatically adjusting the vehicle height during traveling is repeatedly executed. The running vehicle height adjustment process is basically the same as the first vehicle height adjustment process shown in FIG. 3, but the running set time is applied instead of the first set time T1 as the set time in step S104. This running set time is a time during which the vehicle can maintain the vehicle height while running, and is longer than the first set time T1, for example, about several tens of seconds. In such a running vehicle height adjustment process, the control device 45 may set the threshold value ΔHth to a value different from that in the first vehicle height adjustment process, or may set the threshold value ΔHth to the same value. When the state of the vehicle 10 shifts from the running state (vehicle speed v≠0) to the stopped state (vehicle speed v=0), the control device 45 resets the divergence time T of the timer 59 and then ends the running vehicle height adjustment process. Then, the first vehicle height adjustment process described above is repeatedly executed.

An example of the second vehicle height adjustment process will be described with reference to FIG.
As shown in FIG. 4, in the second vehicle height adjustment process, the control device 45 assumes that the vehicle is in a stopped state. It is determined whether or not it is less than the vehicle height adjustment end time Tp2 (step S201). When the elapsed time Tp reaches the vehicle height adjustment end time Tp2 (step S201: NO), the control device 45 resets the elapsed time Tp measured by the timer 59, and then terminates the series of processes. On the other hand, if the elapsed time Tp is less than the vehicle height adjustment end time Tp2 (step S201: YES), the control device 45 determines whether the deviation ΔH of the actual vehicle height from the target vehicle height is equal to or greater than the threshold value ΔHth. (step S202). If the deviation ΔH is less than the threshold ΔHth (step S202: NO), the control device 45 executes the process of step S201 again. If the difference ΔH is greater than or equal to the threshold ΔHth (step S202: YES), the control device 45 starts timing the difference time T by the timer 59 (step S203).

Next, the control device 45 acquires the vehicle height again, calculates the difference ΔH, and determines whether the calculated difference ΔH is equal to or greater than the threshold value ΔHth (step S204). If the deviation ΔH is greater than or equal to the threshold ΔHth (step S204: YES), the control device 45 determines whether or not the deviation time T measured by the timer 59 has reached the second set time T2 (step S205). ). If the deviation time T has reached the second set time T2 (step S205: YES), the control device 45 executes vehicle height adjustment control (step S206).

It is preferable that the second set time T2 is a time during which vehicle height adjustment due to the loading and unloading of the material handling and transporting machine 15 on and off the loading platform 12 is difficult to perform. According to the results of research conducted by the present inventors, the average cargo handling time of the cargo handling and transporting machine 15 (forklift, etc.) on the loading platform 12 is about 1 to 5 depending on the application (based on the difference in the transport object of the cargo handling and transporting machine 15). minutes and the overall average unloading time was approximately 1-2 minutes. Based on these survey results, it is preferable that the second set time T2 be a time included in the range of the average cargo handling time.

Specifically, the second set time T2 is preferably set to a time of 1 minute or longer. By setting the second set time T2 to be one minute or more, the possibility that cargo handling work in the loading platform 12 using the cargo handling and transporting machine 15 is completed before the vehicle height adjustment control is started is increased, and the air consumption of the air tank 42 is increased. You can reduce the amount. Moreover, it is preferable that the second set time T2 is set to a time of 5 minutes or less. By setting the second set time T2 to 5 minutes or less, the amount of air consumed by the air tank 42 is suppressed, and the difference in height between the cargo bed 12 and the platform 14 is suppressed from being equal to or greater than the threshold value ΔHth for a long period of time. As described above, since the average cargo handling time of the material handling and transporting machine 15 on the loading platform 12 is about 1 to 2 minutes, the second set time T2 is obviously longer than the first set time T1, and at least one minute is the first set time. The time is preferably longer than the set time T1. Further, the second set time T2 tends to be longer as the cargo handling time is longer. In the case of such usage, the time may be set according to the usage. Note that the first set time T1 and the second set time T2 are times that cannot be changed through the operation of the controller 49 .

The air suspension system 30 also includes a shock absorber 33 that dampens vibrations of the vehicle 10 . If the deviation ΔH of the vehicle height from the target vehicle height is equal to or greater than the threshold value ΔHth, the shock absorber 33 may be in a bottoming out state in which one end of the piston rod 35 presses the end of the cylinder 34 . Therefore, if the deviation ΔH is equal to or greater than the threshold value ΔHth from when the material handling and transporting machine 15 is driven into the vehicle, the shock absorber 33 may continue to bottom out until the material handling and transporting machine 15 gets off. The continuation of such a state of bottoming out is assumed because the air suspension system 30 is mounted on a truck in which the cargo handling and transporting machine 15 drives into the loading platform 12 . When the bottoming out state continues, not only the mechanical load on the shock absorber 33 increases, but also the mechanical load on the peripheral members of the shock absorber 33 increases because the shock absorber 33 does not exert its load absorbing action. From this point of view, the second set time T2 is preferably selected from a time within the range of 3 minutes±30 seconds, more preferably 3 minutes. By setting the second set time T2 to such a time, even if the shock absorber 33 starts to bottom out when the cargo handling and transporting machine 15 is driven into the vehicle, the bottoming out state will cause excessive damage to the shock absorber 33 and its surrounding members. It will be resolved within the time that the mechanical load can be suppressed. As a result, it is possible to prevent the cargo handling work using the cargo handling and transporting machine 15 from greatly affecting the mechanical strength and durability of the shock absorber 33 and its peripheral members. That is, by setting the second set time T2 to a time within the range of 3 minutes±30 seconds, it is possible to secure a sufficient working time for the material handling and transporting machine 15 within the loading platform 12 and reduce the mechanical load on the shock absorber 33. It is possible to suppress the air consumption of the air tank 42 while obtaining these.

In the vehicle height adjustment control in step S206, the control device 45 controls the leveling valve 43 so that the vehicle height becomes the target vehicle height. That is, in step S206, the controller 45 controls opening and closing of the leveling valve 43 to control the vehicle height to the target vehicle height when the deviation ΔH is equal to or greater than the threshold value ΔHth for the second set time T2. Then, in step S207, the control device 45 resets the difference time T of the timer 59 and executes the process of step S201 again.

On the other hand, if the deviation time T has not reached the second set time T2 (step S205: NO), the control device 45 returns to the process of step S204 and determines again whether the deviation ΔH exceeds the threshold value ΔHth. do. If the deviation ΔH is smaller than the threshold ΔHth (step S204: NO), that is, if the deviation ΔH that was equal to or greater than the threshold ΔHth becomes smaller than the threshold ΔHth, the control device 45 controls the timing unit 59 without performing vehicle adjustment control. is reset (step S207), and the process of step S201 is executed again.

As described above, the control device 45 repeatedly executes the second vehicle height adjustment process for a certain period of time. This certain period of time is preferably a period of time sufficient to complete the cargo handling work using the material handling and transporting machine 15 on the loading platform 12 and a period of time during which excessive power consumption of the battery can be suppressed, for example, about 2 hours. is. This certain period of time is preferably longer as the capacity of the loading platform 12 is larger.

Next, an example of a cargo handling procedure using the cargo handling and transporting machine 15 will be described.
First, after the vehicle 10 is brought into contact with the vehicle berth 13, the start key is turned off. Next, the driver operates the controller 49 to adjust the vehicle height so that the cargo bed 12 and the platform 14 are at approximately the same height. After that, after the rear door of the loading platform 12 is opened, loading/unloading work involving loading and unloading of the loading/unloading machine 15 onto the loading platform 12 is performed. During this cargo handling work, the air suspension system 30 is executing the second vehicle height adjustment process. In the second vehicle height adjustment process, the vehicle height is not adjusted unless the deviation ΔH is greater than or equal to the threshold value ΔHth for the second set time T2. That is, the frequency of vehicle height adjustment due to the loading of the material handling and transporting machine 15 onto the loading platform 12 is suppressed during cargo handling work. As a result, the consumption of air in the air tank 42 can be suppressed.

According to the air suspension control device and the air suspension system of the above embodiment, the effects listed below are obtained.
(1) In the key-on state, the control device 45 executes vehicle height adjustment control on condition that the deviation time T reaches the first set time T1. Therefore, for example, the vehicle can be driven while maintaining the vehicle height at the target vehicle height and preventing hunting during air supply and discharge. On the other hand, in the key-off state, the control device 45 executes the vehicle height adjustment control on condition that the deviation time T reaches the second set time T2. As a result, even during cargo handling work using the cargo handling and transporting machine 15, the frequency of vehicle height adjustment can be suppressed, and the consumption of air associated with vehicle height adjustment can be suppressed. That is, according to the control device 45, in the key-on state, priority is given to maintaining the vehicle height at the target vehicle height, while in the key-off state, the change in vehicle height caused by the loading of the cargo handling and transporting machine onto the loading platform 12 is controlled. Air consumption can be suppressed while coping with this.

(2) The control device 45 has a target setting section 58 that sets a target vehicle height based on an operation signal from the controller 49 . Therefore, since the driver can freely set the target vehicle height, the vehicle height can be matched to the height of the platform 14, for example.

(3) The target setting unit 58 sets the target vehicle height to the vehicle height when the stop signal is input after the input of the rise signal or the descent signal. That is, the vehicle height after the vehicle height adjustment by the driver is set as the target vehicle height. This allows the driver to adjust the vehicle height and set the target vehicle height at the same time. As a result, since no special operation such as target setting is required, the burden on the driver to set the target vehicle height can be reduced.

(4) Setting the first set time T1 to 2 seconds makes it easier to maintain the vehicle height at the target vehicle height. This makes it easier to maintain the vehicle height at the target vehicle height during running.
(5) The second set time T2 is preferably 1 minute or more and 5 minutes or less, more preferably 3 minutes±30 seconds. According to such a configuration, it is possible to reduce the mechanical load on the shock absorber 33 and its peripheral members while securing the working time of the material handling and transporting machine 15 in the loading platform 12 .

It should be noted that the above-described embodiment can be modified as appropriate and implemented as follows.
The target setting unit 58 is not configured to set the vehicle height when the stop unit is operated as the target vehicle height, but may be configured to set, for example, a value individually input through the controller 49 as the target vehicle height. good. The target setting unit 58 has a target setting button for setting the current vehicle height to the target vehicle height. Can be set to high. Further, when cargo handling is performed only at a predetermined specific location, the target vehicle height may be a predetermined specific value.

- In the controller 49, each of the up button 50 and the down button 51 may have a function as a start button and a function as a stop button. That is, the controller 49 may be configured to continue outputting a signal for increasing the vehicle height to the control device 45 only while the lift button 50 is being operated, for example. In this case, the target setting unit 58 of the control device 45 sets the vehicle height at the time when the operation of the raise button 50 is finished as the target vehicle height.

- When the power source of the compressor 41 is a battery, the ACC state may be classified as a key-on state or a key-off state.
- The threshold value ΔHth may be a different value between the first vehicle height adjustment process and the second vehicle height adjustment process. In this case, from the viewpoint of suppressing the air consumption of the air tank 42, it is preferable that the second threshold, which is the threshold for the second vehicle height adjustment process, is larger than the first threshold, which is the threshold for the first vehicle height adjustment process.

As for the threshold ΔHth, the upper threshold that is the threshold when the vehicle height is higher than the target vehicle height and the lower threshold that is the threshold when the vehicle height is lower than the target vehicle height may be different values. . In this case, from the viewpoint of reducing the frequency of the shock absorber 33 bottoming out during cargo handling work, it is preferable that the lower threshold is smaller than the upper threshold.

In the above-described second vehicle height adjustment process, the control device 45, before the elapsed time Tp reaches the vehicle height adjustment end time Tp2 (step S201: YES), if the divergence ΔH becomes equal to or greater than the threshold value ΔHth (step S204: YES), even after the elapsed time Tp reaches the vehicle height adjustment end time Tp2, it is continuously determined whether or not the divergence ΔH is equal to or greater than the threshold value ΔHth. Thereby, the vehicle height adjustment can be performed based on the vehicle height immediately before the elapsed time Tp reaches the vehicle height adjustment end time Tp2. The control device 45 is not limited to such a configuration, and even if the deviation ΔH becomes equal to or greater than the threshold value ΔHth (step S204: YES) before the elapsed time Tp reaches the vehicle height adjustment end time Tp2 (step S201: YES), The second vehicle height adjustment process may be forcibly terminated when the time Tp reaches the vehicle height adjustment end time Tp2.

DESCRIPTION OF SYMBOLS 10... Vehicle, 11... Cab, 12... Loading platform, 13... Car berth, 14... Platform, 15... Material handling and transport machine, 17... Rear front wheel, 18... Rear rear wheel, 19... Body frame, 20... Lower plate, 21 Axle 30 Air suspension system 31 Air spring 32 Air supply/discharge device 33 Shock absorber 34 Cylinder 35 Piston rod 41 Compressor 42 Air tank 43 Leveling valve 44 Air supply/discharge path 45 Control device 46 Key state detector 47 Vehicle height detector 48 Vehicle speed detector 49 Controller 50 Raise button 51 Lower button 52 Stop button 55 ... acquisition unit, 57 ... valve control unit, 58 ... target setting unit, 59 ... timer unit.

Claims (5)

An air suspension control device that constitutes an air suspension system mounted on a vehicle equipped with a loading platform into which a material handling and transporting machine can enter,
The air suspension system is
an air spring;
An air supply/discharge device for supplying/discharging air to the air spring,
The air suspension control device includes:
a key state acquisition unit that acquires a key state that is the state of the start key;
a vehicle height acquisition unit that acquires the vehicle height of the vehicle;
a vehicle speed acquisition unit that acquires the vehicle speed of the vehicle;
a control unit that controls the air supply and discharge device to adjust the vehicle height to a target vehicle height,
The control unit
When the vehicle speed is 0 and the key state is in the on state, the vehicle height is adjusted when the deviation between the vehicle height and the target vehicle height is equal to or greater than a threshold value and continues for a first set time. executing a first vehicle height adjustment process for adjusting the vehicle height to the target vehicle height;
A second step for adjusting the vehicle height to the target vehicle height when the state in which the difference between the vehicle height and the target vehicle height is equal to or greater than a threshold continues for a second set time when the key state is in the OFF state. executing the second vehicle height adjustment process, which is a vehicle height adjustment process and ends when the elapsed time after the key state is turned off reaches a vehicle height adjustment end time;
The air suspension control device , wherein the second set time is an average time of cargo handling work by the cargo handling and transporting machine on the loading platform. an operation signal acquisition unit that acquires an operation signal from an operation unit operated by a driver;
a target setting unit that sets the target vehicle height through the operation signal acquired by the operation signal acquisition unit;
The operation unit has a start button for starting air supply/discharge to/from the air spring and a stop button for stopping air supply/discharge to/from the air spring,
The air suspension control device according to claim 1, wherein the target setting unit sets a vehicle height when the stop button is operated as the target vehicle height. The air suspension control device according to claim 1 or 2, wherein the second set time is set to a time within a range of 1 minute or more and 5 minutes or less. The air suspension control device according to claim 3, wherein the second set time is set to a time within a range of 3 minutes ± 30 seconds. The air suspension control device according to any one of claims 1 to 4, wherein the first set time is a time during which hunting does not occur in supplying and discharging air to and from the air spring.

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