Vehicle height adjusting device

A vehicle height adjusting device includes a vehicle height adjusting unit, a prediction unit, and a vehicle height control unit. The vehicle height adjusting unit adjusts a vehicle height to one of a first state and a second state. In the first state, the vehicle height is set to a predetermined height, and in the second state, the vehicle height is set lower than the first state. The prediction unit predicts whether a drive battery (lower portion) of a vehicle interferes with a road surface in the second state. The vehicle height control unit controls the vehicle height adjusting unit to set the vehicle height to one of the first state and the second state. When the prediction unit predicts an interference between the drive battery of the vehicle and the road surface, the vehicle height adjusting unit restricts a transition from the first state to the second state.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2020-018919 filed on Feb. 6, 2020, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a vehicle height adjusting device.

2. Description of Related Art

Japanese Unexamined Patent Application Publication No. 2002-274144 (JP 2002-274144 A) discloses a vehicle height adjusting device. The vehicle height adjusting device is capable of adjusting the vehicle height by supplying or discharging compressed air to/from the air suspension. This enables so-called kneeling in which the vehicle height is lowered from the normal traveling state in order to improve the ease of getting on and off the vehicle when the vehicle is stopped.

SUMMARY

However, in the case of the configuration disclosed in JP 2002-274144 A, when kneeling is performed when the tire pressure is low or there is an obstacle on the road surface, the lower portion of the vehicle may interfere with the road surface or the like. Therefore, the above prior art has room for improvement in this respect.

The present disclosure provides a vehicle height adjusting device capable of suppressing the lower portion of the vehicle from interfering with the road surface during vehicle height adjustment.

The vehicle height adjusting device according to an aspect of the present disclosure includes: a vehicle height adjusting unit configured to set a vehicle height to a first state or a second state, the first state being a state in which a tire of a vehicle is suspended at a predetermined position with respect to a vehicle body in a vehicle up-down direction, and the second state being a state in which the tire is suspended at a position closer to the vehicle body in the vehicle up-down direction than in the first state; a prediction unit that predicts whether a lower portion of the vehicle interferes with a road surface in the second state; and a vehicle height control unit that controls the vehicle height adjusting unit such that the vehicle height adjusting unit sets the vehicle height to one of the first state and the second state, and that restricts a transition from the first state to the second state by the vehicle height adjusting unit when the prediction unit predicts an interference between the lower portion of the vehicle and the road surface.

According to this configuration, the vehicle height adjusting device includes the vehicle height adjusting unit, the prediction unit, and the vehicle height control unit, and of the above, the vehicle height adjusting unit can set the vehicle height to the first state and the second state. The first state is a state in which the tires of the vehicle are suspended at predetermined positions with respect to the vehicle body in the vehicle up-down direction, and the second state is a state in which the tires are suspended at positions closer to the vehicle body in the vehicle up-down direction as compared with the first state. That is, in the second state, the vehicle height is lower than that in the first state. The prediction unit predicts whether the lower portion of the vehicle interferes with the road surface in the second state. The vehicle height control unit controls the vehicle height adjusting unit to set the vehicle height to one of the first state and the second state. Further, when the prediction unit predicts that the lower portion of the vehicle interferes with the road surface, the vehicle height adjusting unit restricts the transition from the first state to the second state. Therefore, by transitioning from the second state to the first state, it is possible to suppress the lower portion of the vehicle from interfering with the road surface when the vehicle height of the vehicle is lowered (when the vehicle height is adjusted).

Here, the “road surface” includes not only the surface of the actual road but also the shoulder of the road, boundary blocks, foreign matters on the road, road studs and markers embedded in the road surface, road markings, and the like.

The prediction unit may compare an air pressure of the tire of the vehicle, which is detected by an air pressure detecting unit, with a predetermined threshold, and when the detected air pressure is smaller than the predetermined threshold, predict the interference between the lower portion of the vehicle and the road surface.

According to this configuration, the prediction unit compares the air pressures detected by the air pressure detecting unit with the predetermined threshold, and predicts the interference between the lower portion of the vehicle and the road surface when the detected air pressures are smaller than the predetermined threshold. That is, the air pressures of the tires that are easily measured are used for the determination, and it is possible to suppress the lower portion of the vehicle from interfering with the road surface when the transition from the first state to the second state is performed in the state where the lower portion of the vehicle has approached the road surface due to the decrease in the air pressures of the tires. Thus, it is possible to suppress the interference between the lower portion of the vehicle and the road surface during the vehicle height adjustment with a simple configuration.

The vehicle height adjusting device according to the aspect of the present disclosure may include a calculation unit that calculates a remaining interference time until the lower portion of the vehicle interferes with the road surface, based on a rate of decrease in an air pressure of the tire of the vehicle, which is detected by an air pressure detecting unit. The prediction unit may compare the detected air pressure with a predetermined threshold, and when the detected air pressure is smaller than the predetermined threshold and the remaining interference time that has been calculated is shorter than a predetermined time, predict the interference between the lower portion of the vehicle and the road surface.

According to this configuration, the calculation unit calculates the remaining interference time until the lower portion of the vehicle interferes with the road surface based on the rate of decrease in the air pressures of the tires detected by the air pressure detecting unit. The prediction unit compares the detected air pressures with the predetermined threshold, and when the detected air pressures are smaller than the predetermined threshold and the remaining interference time that has been calculated is shorter than the predetermined time, predicts the interference between the lower portion of the vehicle and the road surface. That is, if the transition from the first state to the second state is performed when the rate of decrease in the air pressures of the tires is high due to a flat tire or the like and the remaining interference time is small, the lower portion of the vehicle may interfere with the road surface. That is, by restricting the transition from the first state to the second state when the air pressures of the tires are equal to or smaller than the threshold and the remaining interference time is shorter than the predetermined time, the interference between the lower portion of the vehicle and the road surface can be suppressed. Thus, it is possible to more reliably suppress the interference between the lower portion of the vehicle and the road surface during the vehicle height adjustment.

The vehicle height control unit may temporarily permit the transition from the first state to the second state when the detected air pressure is smaller than a predetermined threshold and the remaining interference time that has been calculated is longer than the predetermined time.

According to this configuration, the vehicle height control unit temporarily permits the transition from the first state to the second state when the detected air pressures are smaller than the predetermined threshold and the remaining interference time is longer than the predetermined time. That is, if the air in the tires is only naturally reduced and not punctured, the remaining interference time increases, and in this case, even if the transition from the first state to the second state is performed, the lower portion of the vehicle may not interfere with the road surface depending on the vehicle height in the second state. Therefore, by temporarily permitting the transition from the first state to the second state, it is possible to expand the available range of the vehicle height adjustment while suppressing the interference between the lower portion of the vehicle and the road surface. In this way, it is possible to suppress the interference between the lower portion of the vehicle and the road surface and improve usability during the vehicle height adjustment at the same time.

The vehicle height adjusting unit may change at least one tire of a plurality of the tires provided in the vehicle to the one of the first state and the second state. The prediction unit may change the predetermined threshold that is compared with an air pressure of the tire for which a state is changed by the vehicle height adjusting unit to a value different from the predetermined threshold that is compared with an air pressure of the tire other than the at least one tire.

According to this configuration, since the vehicle height adjusting unit changes at least one tire of the plurality of the tires provided in the vehicle to one of the first state and the second state, it is possible to save energy as compared with the case of adjusting the vehicle height of the entire vehicle. Further, the prediction unit changes the predetermined threshold that is compared with the air pressure of the tire changed to either the first state or the second state by the vehicle height adjusting unit to a value different from the predetermined threshold that is compared with the air pressure of the tire other than the at least one tire. That is, when the lower portion of the vehicle has already approached the road surface, such as when the air pressure of the tire that is transitioned to the second state has not decreased but the air pressures of the other tires that are not transitioned to the second state have decreased, the predetermined threshold for the tire that is transitioned to the second state can be made larger than the predetermined threshold for the other tires that are not transitioned to the second state. As a result, when the air pressure of the tire corresponding to the position where the vehicle height is adjusted has not decreased but the air pressures of the other tires have decreased and thus the lower portion of the vehicle is approaching the road surface, it is possible to suppress the lower portion of the vehicle from interfering with the road surface due to the transition from the first state to the second state. In this way, it is possible to suppress the interference between the lower portion of the vehicle and the road surface and save energy during the vehicle height adjustment at the same time.

The prediction unit may detect a road surface condition and predict whether the lower portion of the vehicle interferes with the road surface based on the road surface condition.

According to this configuration, since the prediction unit predicts whether the lower portion of the vehicle interferes with the road surface from the road surface condition detected by the road surface detecting unit, it is possible to suppress the interference between the lower portion of the vehicle and the road surface based on the actual situation of the vehicle. Thus, it is possible to suppress the interference between the lower portion of the vehicle and the road surface during the vehicle height adjustment according to various situations.

The vehicle may be equipped with a battery in a lower portion of the vehicle.

According to this configuration, the vehicle is equipped with the battery in the lower portion of the vehicle. By mounting the battery in the lower portion of the vehicle where a space is relatively easily secured, the battery can be increased in size and the battery can be suppressed from interfering with the road surface. In this way, the battery can be protected.

The vehicle height adjusting device according to the aspect of the present disclosure may include a display generation unit that generates a warning when the vehicle height control unit restricts the transition from the first state to the second state; and a display unit that displays the warning generated by the display generation unit to an occupant of the vehicle.

According to this configuration, since the vehicle height adjusting device includes the display generation unit that generates a warning and the display unit for displaying the warning generated by the display generation unit to the occupant of the vehicle when the vehicle height control unit restricts the transition from the first state to the second state, the occupant can grasp that the transition from the first state to the second state is restricted. In this way, it is easier for the occupant to grasp the situation of the vehicle.

DETAILED DESCRIPTION OF EMBODIMENTS

First Embodiment

Hereinafter, a vehicle height adjusting device10will be described according to a first embodiment with reference toFIGS.1to4B. Hereinafter, when the description is made simply using terms indicating directions i.e., forward and rearward, right and left, and upward and downward, these means forward and rearward in the vehicle front-rear direction, right and left in the vehicle right-left direction (vehicle width direction), and upward and downward in the vehicle up-down direction unless otherwise specified.

Hardware Configuration

FIG.1is a block diagram showing a hardware configuration of the vehicle height adjusting device10. The vehicle height adjusting device10is provided in the vehicle12(seeFIGS.4A and4B), and includes an air suspension device14, a tire pressure detecting device16, a display device18, an operation device20, and a control device22. Each component is connected to each other via an in-vehicle network23.

As an example, the vehicle12is an electric vehicle and a shared vehicle in which a drive battery24serving as a battery is mounted on the lower portion (under the floor) of the vehicle (seeFIGS.4A and4B), and has an entrance and exit (not shown) for occupants on one side in the vehicle width direction. The vehicle12has a plurality of (four in the present embodiment) tires26(seeFIGS.4A and4B), and each of the tires26is suspended from the vehicle body by the air suspension device14.

The air suspension device14includes air springs, an air tank, a valve, and a control unit (all not shown). Each of the air springs is provided between an axle, which serves as the center of rotation of each tire26, and the vehicle body and expands substantially in the vehicle up-down direction with air supplied to the inside. Due to the expansion of the air springs, the tires26and the vehicle body are distanced from each other in the vehicle up-down direction, so that the vehicle height of the vehicle12is increased. On the other hand, the air springs contract substantially in the vehicle up-down direction when air is discharged from the inside. Due to the contraction of the air springs, the tires26and the vehicle body approach each other in the vehicle up-down direction, so that the vehicle height of the vehicle12is lowered. The air springs are connected to the air tank, and the valve controlled by the control unit enables the movement of air between the air springs and the air tank. Thus, the vehicle height of the vehicle12can be adjusted by controlling the control unit. The air suspension device14is capable of transmitting expansion/contraction information of the air springs to the control device22.

The tire pressure detecting device16includes air pressure sensors, a receiver, and an air pressure sensor control device (all not shown). Each of the air pressure sensors is fixed to the rim portion of a wheel (not shown) of each tire26, and detects the air pressure in the tire26. The detected air pressure is transmitted to the receiver through wireless signals. The receiver transmits the received wireless signals to the air pressure sensor control device that is communicably connected to the receiver. The air pressure sensor control device calculates the air pressures in the tires26based on the signals received from the receiver, and transmits the calculated air pressures as air pressure information to the control device22, whereby the control device22stores the air pressure information. With the above configuration, the air pressure of each tire26is detected.

The display device18includes a display panel18A as a display unit and a display control device18B as a display generation unit. The display panel18A is composed of a liquid crystal panel provided in the meter cluster of the instrument panel provided in the driver's seat, and can display various displays to the vehicle cabin, such as a warning generated by the display control device18B that is communicably connected to the display panel18A.

The operation device20includes an operation button (not shown) provided on the instrument panel of the driver's seat. The operation button is used by the occupant to set the vehicle height to either the first state or the second state to adjust the vehicle height.

The control device22has therein a central processing unit (CPU)28, a read only memory (ROM)30, a random access memory (RAM)32, and a storage34. Each configuration is communicably connected to each other via a bus36.

The CPU28is a central arithmetic processing unit that executes various programs and controls each unit. That is, the CPU28reads a program from the ROM30or the storage34, and executes the program using the RAM32as a work area. The CPU28controls each of the above configurations and performs various arithmetic processes according to the programs stored in the ROM30or the storage34. In the present embodiment, the ROM30or the storage34stores a vehicle height adjusting program for adjusting the vehicle height of the vehicle12.

The ROM30stores various programs and various data. The RAM32temporarily stores a program or data as a work area. The storage34is composed of a hard disk drive (HDD) or a solid state drive (SSD), and stores various programs including an operating system and various data.

Functional Configuration

When executing the above-described vehicle height adjusting program, the vehicle height adjusting device10realizes various functions using the above-described hardware resources. The functional configuration realized by the vehicle height adjusting device10will be described.

FIG.2is a block diagram showing an example of the functional configuration of the vehicle height adjusting device10.

As shown inFIG.2, the vehicle height adjusting device10has an air pressure detecting unit38, a prediction unit40, a vehicle height control unit42, a display control unit44, and a vehicle height adjusting unit46as the functional configuration. The CPU28of the control device22reads and executes the vehicle height adjusting program stored in the ROM30or the storage34(seeFIG.1), thereby realizing each functional configuration.

The air pressure detecting unit38acquires the air pressure information of each tire26from the tire pressure detecting device16and transmits the air pressure information to the prediction unit40.

The prediction unit40compares the air pressure of the tire26based on the air pressure information received from the air pressure detecting unit38with a predetermined threshold, and predicts whether the drive battery24of the vehicle12interferes with the road surface based on the comparison result. Specifically, when the air pressure of any of the tires26is smaller than the threshold, the distance between the drive battery24of the vehicle12and the road surface is smaller than when the air pressure is larger than the threshold. If a transition from the first state to the second state, which will be described later, is performed in this state, there is a high possibility that the drive battery24of the vehicle12interferes with the road surface. Thus, when the air pressure of the tire26is smaller than the threshold, the prediction unit40predicts that the drive battery24of the vehicle12interferes with the road surface, and transmits the prediction result to the vehicle height control unit42.

The vehicle height control unit42controls the vehicle height adjusting unit so that the vehicle height of the vehicle12is set to either the first state or the second state based on the input from the operation device20, and on receiving from the prediction unit40the prediction result that the drive battery24of the vehicle12interferes with the road surface, restricts the transition from the first state to the second state. When restricting the transition from the first state to the second state, the vehicle height control unit42transmits the information to the display control unit44.

The display control unit44acquires and controls the operating status and display contents of the display device18, and on receiving information from the vehicle height control unit42to restrict the transition from the first state to the second state, controls the display device18such that the display device18displays a warning indicating the restriction. Thus, the display device18generates a warning indicating that the transition from the first state to the second state is restricted, and displays the warning.

The vehicle height adjusting unit46controls the air suspension device14according to the determination result of the vehicle height control unit42. Specifically, the vehicle height adjusting unit46controls the air suspension device14so that the vehicle height of the vehicle12is set to either the first state or the second state. The first state is a state in which the vehicle12is in a normal traveling state, and is a state in which the air springs of the air suspension device14are expanded and the tires26are suspended at predetermined positions with respect to the vehicle body in the vehicle up-down direction. As a result, the vehicle height becomes a predetermined height. Specifically, the predetermined vehicle height in the first state is a vehicle height in which the distance between a member of the vehicle12located at the lowermost end of the vehicle12(drive battery24as an example in the present embodiment) and the road surface is equal to or larger than the minimum ground height defined by the safety standard. On the other hand, the second state is a state in which the occupants get on and off the vehicle12, and is a state in which the air springs of the air suspension device14are contracted and the tires26are suspended at positions closer to the vehicle body in the vehicle up-down direction as compared with the first state. The vehicle height in the second state is a state in which the vehicle height is lower than that in the first state to such an extent that the drive battery24does not interfere with the road surface. In the vehicle12, the first state is the basic state.

Processing Flow

Next, the operation of the vehicle height adjusting device10will be described.FIG.3is a flowchart showing the flow of operation of the vehicle height adjusting device10. The CPU28reads the vehicle height adjusting program from the ROM30or the storage34, runs the program in the RAM32, and executes the program, thereby performing the vehicle height adjustment.

The CPU28determines whether the vehicle12has been operated by the operation device20to transition from the first state to the second state (step S100). When the operation of the transition from the first state to the second state is not performed (step S100: NO), the CPU28ends the process based on the vehicle height adjusting program.

When the operation of the transition from the first state to the second state is performed (step S100: YES), the CPU28acquires the air pressure information of each tire26from the tire pressure detecting device16(step S102). Then, the CPU28determines whether the acquired air pressures of the tires26are smaller than the threshold (step S104). When the acquired air pressures of the tires26are smaller than the threshold (step S104: YES), the CPU28restricts the transition of the vehicle12from the first state to the second state (step S106).

Subsequently, the CPU28determines whether the display device18has already displayed a warning indicating that the transition from the first state to the second state is restricted (step S108). When the warning indicating that the transition from the first state to the second state is restricted is already being displayed on the display device18(when a warning indicating that the transition from the first state to the second state is restricted has been displayed at the time of the previous operation and the warning remains displayed) (step S108: YES), the CPU28ends the process based on the vehicle height adjusting program. On the other hand, when the display device18does not display a warning indicating that the transition from the first state to the second state is restricted (step S108: NO), the CPU28causes the display device18to display the warning indicating that the transition from the first state to the second state is restricted (step S110). After that, the processing based on the vehicle height adjusting program is ended.

When the air pressures of the tires26acquired in step S104are larger than the threshold (step S104: NO), the CPU28determines whether the display device18has already displayed a warning indicating that the transition from the first state to the second state is restricted (step S112). When the display device18does not display a warning indicating that the transition from the first state to the second state is restricted (step S112: NO), the CPU28transitions to the process of step S116described later.

When the display device18displays a warning indicating that the transition from the first state to the second state is restricted (step S112: YES), the CPU28causes the display device18to stop displaying the warning indicating that the transition from the first state to the second state is restricted (step S114), and transitions the vehicle height from the first state to the second state (step S116). After that, the processing based on the vehicle height adjusting program is ended.

Operations and Effects of First Embodiment

Next, operations and effects of the first embodiment will be described.

In the present embodiment, as shown inFIG.2, the vehicle height adjusting device10includes the vehicle height adjusting unit46, the prediction unit40, and the vehicle height control unit42, and of the above, the vehicle height adjusting unit46can set a vehicle height to a first state and a second state. The first state is a state in which the tires26of the vehicle12are suspended at predetermined positions with respect to the vehicle body in the vehicle up-down direction (seeFIG.4A), and the second state is a state in which the tires26are suspended at positions closer to the vehicle body in the vehicle up-down direction as compared with the first state (seeFIG.4B). That is, in the second state, the vehicle height is lower than that in the first state. The prediction unit40predicts whether the drive battery24(lower portion) of the vehicle12interferes with the road surface in the second state. The vehicle height control unit42controls the vehicle height adjusting unit46to set the vehicle height to either the first state or the second state. Further, when the prediction unit40predicts that the lower portion of the vehicle12interferes with the road surface, the vehicle height adjusting unit46restricts the transition from the first state to the second state. Therefore, by transitioning from the second state to the first state, it is possible to suppress the drive battery24of the vehicle12from interfering with the road surface when the vehicle height of the vehicle12is lowered. As a result, it is possible to suppress the drive battery24of the vehicle12from interfering with the road surface during the vehicle height adjustment.

Further, the prediction unit40compares the air pressures detected by the air pressure detecting unit38with a predetermined threshold, and predicts the interference between the drive battery24of the vehicle12and the road surface when the air pressures are smaller than the threshold. That is, the air pressures of the tires26that are easily measured are used for the determination, and it is possible to suppress the drive battery24of the vehicle12from interfering with the road surface when the vehicle12is transitioned from the first state to the second state in the state in which the drive battery24of the vehicle12has approached the road surface due to the decrease in the air pressures of the tires26. Thus, it is possible to suppress the drive battery24of the vehicle12from interfering with the road surface during the vehicle height adjustment with a simple configuration.

Further, the vehicle12is equipped with the drive battery24in the lower portion of the vehicle12. Thus, by mounting the drive battery24in the lower portion of the vehicle12where a space is relatively easily secured, the drive battery24can be increased in size and the drive battery24can be suppressed from interfering with the road surface. Therefore, the drive battery24can be protected.

Furthermore, since the vehicle height adjusting device10includes the display control device18B that generates a warning and the display panel18A for displaying the warning generated by the display control device18B to the occupant of the vehicle12when the vehicle height control unit42restricts the transition from the first state to the second state, the occupant can grasp that the transition from the first state to the second state is restricted. This makes it easier for the occupant to grasp the situation of the vehicle12.

Second Embodiment

Next, the vehicle height adjusting device according to the second embodiment of the present disclosure will be described with reference toFIGS.5to7. The same components as those in the first embodiment, etc. described above are denoted by the same reference signs and the description thereof will be omitted.

A vehicle height adjusting device60according to the second embodiment has the same basic configuration as that of the first embodiment, and is characterized in that a calculation unit62is provided.

Functional Configuration

That is, the vehicle height adjusting device60is provided in the vehicle12(seeFIGS.4A and4B), and includes the air suspension device14, the tire pressure detecting device16, the display device18, the operation device20, and the control device22. Each component is connected to each other via the in-vehicle network23(seeFIG.1).

Functional Configuration

When executing the vehicle height adjusting program, the vehicle height adjusting device60realizes various functions using the above-described hardware resources. The functional configuration realized by the vehicle height adjusting device60will be described.

FIG.5is a block diagram showing an example of the functional configuration of the vehicle height adjusting device60.

As shown inFIG.5, the vehicle height adjusting device60has the air pressure detecting unit38, the calculation unit62, a prediction unit66, a vehicle height control unit68, the display control unit44, and the vehicle height adjusting unit46as the functional configuration. The CPU28of the control device22reads and executes the vehicle height adjusting program stored in the ROM30or the storage34(seeFIG.1), thereby realizing each functional configuration.

The calculation unit62acquires the expansion/contraction information of the air springs from the air suspension device14and estimates the current vehicle height of the vehicle12. Further, the calculation unit62stores the air pressure information received from the air pressure detecting unit38and calculates the fluctuation of the air pressures from the absolute values of the air pressures at a predetermined time. That is, the calculation unit62calculates a remaining interference time Ct (seeFIG.7) indicating the time remaining until the drive battery24of the vehicle12and the road surface interfere with each other, based on the rate of decrease in the air pressures calculated including the absolute values of the air pressures and a parameter related to the time. Specifically, the rate of decrease in the air pressures of the tires26is calculated by acquiring the absolute values of the air pressures at a plurality of time points within a predetermined time and calculating the amount of change (inclination) in the values of the air pressures. Then, based on the fluctuation, the calculation unit62calculates the approach speed at which the drive battery24of the vehicle12approaches the road surface and the remaining interference time Ct until the drive battery24of the vehicle12interferes with the road surface from the current vehicle height. The calculation unit62transmits the current vehicle height information and the remaining interference time information to the prediction unit66.

The prediction unit66acquires the air pressure information of each tire26from the tire pressure detecting device16and compares the air pressures of the tires26with the threshold. At this time, when the air pressure of any of the tires26is smaller than the threshold, the prediction unit66determines that the tires26are in an air-reduced state, and compares the remaining interference time received from the calculation unit62with the predetermined time. Based on the comparison result, the prediction unit66predicts whether the drive battery24of the vehicle12interferes with the road surface. Specifically, as shown inFIG.7, the prediction unit66compares the remaining interference time Ct at the current vehicle height and the time Ut (hereinafter referred to as “raising time”) that serves as the predetermined time and that is required to raise the vehicle height by the air suspension device14until the vehicle height reaches the first state. When comparison result shows that the remaining interference time Ct is shorter than the raising time Ut (corresponding to area A inFIG.7), even when the vehicle height is increased by the air suspension device14, the vehicle height decreases faster than the increase in the vehicle height by the air suspension device14due to the decrease in the air pressure of the tires26. That is, when the current vehicle height of the vehicle12is X, the remaining interference time Ct is t1and the raising time Ut is t2. Thus, since the raising time Ut is longer than the remaining interference time Ct, even when the vehicle height is raised by the air suspension device14, the raising speed cannot keep up with the decrease in the vehicle height, and there is a high possibility that the drive battery24of the vehicle12interferes with the road surface. Therefore, when the air pressure of any of the tires26is smaller than the threshold and the remaining interference time Ct is shorter than the raising time Ut, it is predicted that the drive battery24of the vehicle12interferes with the road surface, and the prediction result is transmitted to the vehicle height control unit42. As an example, a case where “the remaining interference time Ct is shorter than the raising time Ut” includes a case of a flat tire or the like caused by damage to the tire26by a foreign matter.

As shown inFIG.6, the vehicle height control unit68temporarily permits the transition from the first state to the second state when the air pressure of the tire26is determined by the prediction unit66to be smaller than a predetermined threshold and the remaining interference time Ct is longer than the raising time Ut, that is, when the vehicle height of the vehicle12falls under a range other than the area A inFIG.7. That is, if the air in the tire26is naturally reduced and not punctured, the approach speed is slower. In this case, the vehicle height is raised by the air suspension device14to suppress the drive battery24of the vehicle12from interfering with the road surface. The vehicle height control unit68temporarily permits the transition from the first state to the second state within a range in which the vehicle height of the vehicle12does not reach the area A inFIG.7.

Processing Flow

Next, the operation of the vehicle height adjusting device10will be described.FIG.6is a flowchart showing the flow of operation of the vehicle height adjusting device60. The CPU28reads the vehicle height adjusting program from the ROM30or the storage34, runs the program in the RAM32, and executes the program, thereby performing the vehicle height adjustment. The same processes as those in the first embodiment are denoted by the same reference signs and the description thereof will be omitted.

In step S104, when the acquired air pressures of the tires26are smaller than the threshold (step S104: YES), the CPU28calculates the approach speed and the remaining interference time Ct (step S200).

The CPU28compares the remaining interference time Ct with the raising time Ut (step S202), and determines whether the remaining interference time Ct is shorter than the raising time Ut (step S204). When the remaining interference time Ct is shorter than the raising time Ut (step S204: YES), the CPU28proceeds to the process of step S106.

On the other hand, when the remaining interference time Ct is longer than the raising time Ut (step S204: NO), the CPU28temporarily permits the transition from the first state to the second state (step S206), and proceeds to the process of step S200.

Operations and Effects of Second Embodiment

Next, operations and effects of the second embodiment will be described.

The above configuration has the same configuration as the vehicle height adjusting device10of the first embodiment except that the calculation unit62is provided, so that the same effect as that of the first embodiment can be obtained. Further, the calculation unit62calculates the remaining interference time Ct until the drive battery24of the vehicle12interferes with the road surface, from the rate of decrease in the air pressures of the tires26detected by the air pressure detecting unit38, that is, the rate of decrease in the air pressures calculated including the absolute values of the air pressures and the parameter related to the time. The prediction unit66compares the air pressures with a predetermined threshold, and predicts the interference between the drive battery24of the vehicle12and the road surface when the air pressures are smaller than the threshold and the remaining interference time Ct calculated by the calculation unit62is shorter than the raising time Ut. That is, if the transition from the first state to the second state is performed when the rate of decrease in the air pressures of the tires26is high due to a flat tire or the like and the remaining interference time Ct is small, the lower portion of the vehicle12may interfere with the road surface. That is, by restricting the transition from the first state to the second state when the air pressures of the tires26are equal to or smaller than the threshold and the remaining interference time Ct is shorter than the raising time Ut, the interference between the drive battery24of the vehicle12and the road surface can be suppressed. As a result, it is possible to more reliably suppress the drive battery24of the vehicle12from interfering with the road surface during the vehicle height adjustment.

Further, the vehicle height control unit68temporarily permits the transition from the first state to the second state when the air pressures are smaller than the threshold and the remaining interference time Ct is longer than the raising time Ut. That is, if the air in the tires26is only naturally reduced and not punctured, the remaining interference time Ct increases, and in this case, even if the transition from the first state to the second state is performed, the drive battery24of the vehicle12may not interfere with the road surface depending on the vehicle height in the second state. Therefore, by temporarily permitting the transition from the first state to the second state, it is possible to expand the available range of the vehicle height adjustment while suppressing the interference between the drive battery24of the vehicle12and the road surface. As a result, it is possible to suppress interference between the drive battery24of the vehicle12and the road surface and improve usability during the vehicle height adjustment at the same time.

In the second embodiment described above, when the air pressures of the tires26are equal to or smaller than the threshold and the remaining interference time Ct is shorter than the raising time Ut, the transition from the first state to the second state is restricted. However, the present disclosure is not limited to this, and the transition from the first state to the second state may be restricted when the remaining interference time Ct is shorter than the raising time Ut, even if the air pressures of the tires26are equal to or larger than the threshold.

Further, the calculation unit62is configured to calculate the rate of decrease in the air pressures by acquiring the absolute values of the air pressures at a plurality of time points within a predetermined time and calculating the amount of change in the values of the air pressures. However, the present disclosure is not limited to this, and the configuration may be such that the air pressures are constantly detected and the rate of decrease in the air pressures is calculated from the detected change in the air pressures.

Third Embodiment

Next, the vehicle height adjusting device according to the third embodiment of the present disclosure will be described with reference toFIGS.1,2,8, and9. The same components as those in the first embodiment, etc. described above are denoted by the same reference signs and the description thereof will be omitted.

A vehicle height adjusting device70according to the third embodiment has the same basic configuration as that of the first embodiment, and is characterized in that the expansion of the air spring corresponding to at least one tire26of the four tires26of the vehicle12is adjustable.

Overall Configuration

That is, the vehicle height adjusting device70is provided in the vehicle12(seeFIG.8), and includes the air suspension device14, the tire pressure detecting device16, the display device18, an operation device72, and the control device22. Each component is connected to each other via the in-vehicle network23(seeFIG.1). The operation device72is configured to include operation buttons for individually adjusting the expansion of the air springs corresponding to the four tires26of the vehicle12. As a result, as shown inFIG.8, only the side of the vehicle12where the entrance/exit is provided in the vehicle width direction is set in the second state, so that the vehicle height on the entrance/exit side is lowered to reduce the step height between the vehicle12and the ingress/egress platform.

This makes it easier for occupants to get on and off the vehicle.

Functional Configuration

When executing the vehicle height adjusting program, the vehicle height adjusting device70realizes various functions using the above-described hardware resources. The functional configuration realized by the vehicle height adjusting device70will be described.

As shown inFIG.2, the vehicle height adjusting device70has the air pressure detecting unit38, a prediction unit76, a vehicle height control unit78, the display control unit44, and a vehicle height adjusting unit74as the functional configuration. The CPU28of the control device22reads and executes the vehicle height adjusting program stored in the ROM30or the storage34(seeFIG.1), thereby realizing each functional configuration.

The prediction unit76acquires from the air pressure detecting unit38the air pressure information of the tire26at the portion where the vehicle height is adjusted and compares the air pressure of the tire26with the threshold. The prediction unit76predicts whether the drive battery24of the vehicle12interferes with the road surface based on the comparison result. Specifically, when the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold, the distance between the drive battery24of the vehicle12and the road surface is smaller than when the air pressure is larger than the threshold. If the transition from the first state to the second state is performed in this state, there is a high possibility that the drive battery24of the vehicle12interferes with the road surface. Therefore, when the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold, the prediction unit76predicts that the drive battery24of the vehicle12interferes with the road surface, and transmits the prediction result to the vehicle height control unit42.

Further, even when the air pressure of the tire26at the portion where the vehicle height is adjusted is larger than the threshold, if there is a portion where the vehicle height is not adjusted, the prediction unit76compares the air pressures of the other tires26corresponding to the portions where the vehicle height is not adjusted with the threshold. When the air pressures are smaller than the threshold, the prediction unit76resets the threshold to a value that is set larger than the threshold, and compares the air pressure of the tire26at the portion where the vehicle height is adjusted with the threshold (changed threshold) again. That is, when the air pressures of the other tires26corresponding to the portions where the vehicle height is not adjusted are smaller than the threshold, the vehicle height may have already lowered even if the air pressure of the tire26at the portion where the vehicle height is adjusted is larger than the threshold. If the portion where the vehicle height is adjusted is transitioned from the first state to the second state in this state, the drive battery24of the vehicle12may interfere with the road surface. Therefore, the air pressure of the tire26corresponding to the portion where the vehicle height is adjusted is compared with the threshold that is reset (increased) to a value that takes into account the decrease in the vehicle height due to the fact that the air pressures of the other tires26corresponding to the portions where the vehicle height is not adjusted are smaller than the threshold. When the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold, the prediction unit76predicts that the drive battery24of the vehicle12interferes with the road surface, and transmits the prediction result to the vehicle height control unit78.

The vehicle height control unit78controls the vehicle height adjusting unit74so that at least one tire26of the four tires of the vehicle12is set to either the first state or the second state based on the input from the operation device72, and on receiving from the prediction unit76the prediction result that the drive battery24of the vehicle12interferes with the road surface, restricts the transition from the first state to the second state. When restricting the transition from the first state to the second state, the vehicle height control unit78transmits the information to the display control unit44.

The vehicle height adjusting unit74controls the air suspension device14corresponding to the at least one tire26of the four tires26of the vehicle12according to the determination result of the vehicle height control unit78. In the vehicle12, the first state is the basic state.

Processing Flow

Next, the operation of the vehicle height adjusting device70will be described.FIG.9is a flowchart showing the flow of operation of the vehicle height adjusting device10. The CPU28reads the vehicle height adjusting program from the ROM30or the storage34, runs the program in the RAM32, and executes the program, thereby performing the vehicle height adjustment. The same processes as those in the first embodiment are denoted by the same reference signs and the description thereof will be omitted.

The CPU28determines whether the at least one tire26of the four tires26of the vehicle12has been operated by the operation device72to transition from the first state to the second state (step S300). When the operation of the transition from the first state to the second state is not performed (step S300: NO), the CPU28ends the process based on the vehicle height adjusting program.

When the operation of the transition from the first state to the second state is performed (step S300: YES), the CPU28proceeds to the process of step S102.

After acquiring the air pressure information of each tire26from the tire pressure detecting device16in step S102, the CPU28determines whether the air pressure of the tire26that is operated to transition from the first state to the second state (at the portion where the vehicle height is adjusted) is smaller than the threshold (step S302). When the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold (step S302: YES), the CPU28proceeds to the process of step S106.

On the other hand, when the air pressure of the tire26at the portion where the vehicle height is adjusted is larger than the threshold (step S302: NO), the CPU28determines whether there is a portion where the vehicle height is not adjusted in the operation of the operation device72(step S304). When there is no portion where the vehicle height is not adjusted (that is, when the vehicle height of the entire vehicle12is adjusted) (step S304: NO), the CPU28proceeds to the process of step S112.

When there is a portion where the vehicle height is not adjusted (that is, when the vehicle height of a part of the vehicle12is adjusted) (step S304: YES), the CPU28determines whether the air pressures of the other tires26at the portions where the vehicle height is not adjusted are smaller than the threshold (step S306). When the air pressures of the other tires26at the portions where the vehicle height is not adjusted are larger than the threshold (step S306: NO), the CPU28proceeds to the process of step S112.

When the air pressures of the other tires26at the portions where the vehicle height is not adjusted are smaller than the threshold (step S306: YES), the CPU28increases the value of the threshold (step S308). Then, the CPU28determines whether the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold that has been changed in step S308(step S310). When the air pressure of the tire26at the portion where the vehicle height is adjusted is larger than the threshold that has been changed in step S308(step S310: NO), the CPU28proceeds to the process of step S112.

When the air pressure of the tire26at the portion where the vehicle height is adjusted is smaller than the threshold that has been changed in step S308(step S310: YES), the CPU28proceeds to the process of step S106.

Operations and Effects of Third Embodiment

Next, operations and effects of the third embodiment will be described.

The above configuration is the same as that of the vehicle height adjusting device10of the first embodiment except that the expansion of the air spring corresponding to the at least one tire26of the four tires26of the vehicle12can be adjusted. Therefore, the same effect as that of the first embodiment can be obtained. Further, since the vehicle height adjusting unit74changes the at least one tire26of the plurality of tires26provided in the vehicle12to either the first state or the second state, it is possible to save energy as compared with the case of adjusting the vehicle height of the entire vehicle. Further, the prediction unit76changes the threshold that is compared with the air pressure of the tire26changed to either the first state or the second state by the vehicle height adjusting unit74to a value different from the threshold that is compared with the air pressure of the tire26at other portions. That is, when the drive battery24of the vehicle12has already approached the road surface, such as when the air pressure of the tire26that is transitioned to the second state has not decreased but the air pressures of the other tires26that are not transitioned to the second state have decreased, the threshold for the tire26that is transitioned to the second state can be made larger than the threshold for the other tires26that are not transitioned to the second state. As a result, when the air pressure of the tire26corresponding to the position where the vehicle height is adjusted has not decreased but the air pressures of the other tires26have decreased and thus the drive battery24of the vehicle12has approached the road surface, it is possible to suppress the lower portion of the vehicle12from interfering with the road surface due to the transition from the first state to the second state. As a result, it is possible to suppress interference between the drive battery24of the vehicle12and the road surface and save energy during the vehicle height adjustment at the same time.

Fourth Embodiment

Next, the vehicle height adjusting device according to the fourth embodiment of the present disclosure will be described with reference toFIGS.10to12. The same components as those in the first embodiment, etc. described above are denoted by the same reference signs and the description thereof will be omitted.

A vehicle height adjusting device80according to the fourth embodiment has the same basic configuration as that of the first embodiment, and is characterized in that the vehicle height adjusting device80detects the road surface condition and determines whether the drive battery24of the vehicle12interferes with the road surface based on the detection result.

Overall Configuration

That is, the vehicle height adjusting device80is provided in the vehicle12(seeFIGS.4A and4B), and includes the air suspension device14, an image capturing device82, the display device18, the operation device20, and the control device22as shown inFIG.10. Each component is connected to each other via the in-vehicle network23.

As an example, the image capturing device82is provided in the lower portion of the vehicle12and includes a camera that captures an image of the road surface on the lower side of the vehicle. The captured image is transmitted to the control device22.

Functional Configuration

When executing the vehicle height adjusting program, the vehicle height adjusting device80realizes various functions using the above-described hardware resources. The functional configuration realized by the vehicle height adjusting device80will be described.

FIG.11is a block diagram showing an example of the functional configuration of the vehicle height adjusting device80.

As shown inFIG.11, the vehicle height adjusting device60has a road surface detecting unit84, a prediction unit86, the vehicle height control unit42, the display control unit44, and the vehicle height adjusting unit46as the functional configuration. The CPU28of the control device22reads and executes the vehicle height adjusting program stored in the ROM30or the storage34(seeFIG.10), thereby realizing each functional configuration.

The road surface detecting unit84acquires the image taken by the image capturing device82and transmits the image to the prediction unit86.

The prediction unit86detects the road surface condition based on the image received from the road surface detecting unit84. Specifically, the prediction unit86analyzes the captured image to determine whether there is foreign matter, steps, or the like on the lower side of the vehicle12. The prediction unit86calculates the distance between the road surface, the foreign matter or the like, if any, and the drive battery24or the like of the vehicle12. When the prediction unit86determines from the presence/absence of the foreign matter or the like and the calculated distance that the drive battery24of the vehicle12is likely to interfere with the road surface or the foreign matter or the like due to the transition from the first state to the second state, the prediction unit86predicts that the drive battery24of the vehicle12interferes with the road surface, and transmits the result to the vehicle height control unit42.

Processing Flow

Next, the operation of the vehicle height adjusting device80will be described.FIG.12is a flowchart showing the flow of operation of the vehicle height adjusting device80. The CPU28reads the vehicle height adjusting program from the ROM30or the storage34, runs the program in the RAM32, and executes the program, thereby performing the vehicle height adjustment. The same processes as those in the first embodiment are denoted by the same reference signs and the description thereof will be omitted.

When the operation of the transition from the first state to the second state is performed in step S100(step S100: YES), the CPU28causes the image capturing device82to capture the image of the road surface on the lower side of the vehicle (step S400). Then, the CPU28determines whether the drive battery24of the vehicle12interferes with the road surface, foreign matter, or the like based on the analysis result of the captured image (step S402). When the drive battery24of the vehicle12interferes with the road surface, foreign matter, or the like based on the analysis result of the captured image (step S402: YES), the CPU28proceeds to the process of step S106. On the other hand, when the drive battery24of the vehicle12does not interfere with the road surface, foreign matter, or the like based on the analysis result of the captured image (step S402: NO), the CPU28proceeds to the process of step S112.

Operations and Effects of Fourth Embodiment

Next, operations and effects of the fourth embodiment will be described.

The above configuration has the same configuration as the vehicle height adjusting device10of the first embodiment except that the road surface condition is detected and whether the drive battery24of the vehicle12interferes with the road surface is predicted based on the detection result. Therefore, the same effect as that of the first embodiment can be obtained. Further, since the prediction unit86predicts whether the drive battery24of the vehicle12interferes with the road surface from the road surface condition detected by the road surface detecting unit84, it is possible to suppress the interference between the drive battery24of the vehicle12and the road surface based on the actual situation of the vehicle12. Thus, it is possible to suppress the drive battery24of the vehicle12from interfering with the road surface during the vehicle height adjustment depending on various situations.

In the present embodiment, the road surface condition is detected based on the analysis result of the image captured by the image capturing device82, but the present disclosure is not limited to this, and the road surface condition may be detected by a sensor that can acquire the road surface, a shape of a foreign matter, and distance information, such as a radar, an ultrasonic wave, and a laser imaging detection and ranging (LIDAR). Further, a configuration that predicts the interference based on the air pressures of the tires26as in the first to third embodiments may be combined.

Further, in the first to fourth embodiments described above, the occupant operates the vehicle12during the vehicle height adjustment, but the present disclosure is not limited to this. The vehicle height adjusting program may be automatically executed based on the position information of the vehicle12, the determination result of a proximity sensor, and the like, in cases such as when the vehicle12arrives at a predetermined place such as a bus stop. Further, in cases such as when the power unit of the vehicle12is turned ON, the vehicle height adjusting program may be automatically executed at a timing before the operation of the vehicle12and the occupant may be notified before the operation of whether the transition from the first state to the second state is available.

Further, the interference between the drive battery24of the vehicle12and the road surface is suppressed, but the present disclosure is not limited to this, and the interference between the road surface and members other than the drive battery24such as suspension members may be suppressed.

Furthermore, the vehicle12is configured to be provided with four tires26, but the present disclosure is not limited to this, and the vehicle12may be configured to be provided with three tires or five or more tires.

Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above embodiments, and various modifications other than the above can be carried out without departing from the spirit of the present disclosure.