JP4816577B2 - Vehicle height adjustment device - Google Patents

Description

  The present invention relates to a fail-safe technique in the case where a malfunction occurs in a vehicle height adjusting device, particularly a system of the vehicle height adjusting device.

2. Description of the Related Art Conventionally, there is a vehicle equipped with a vehicle height adjusting device that changes the vehicle height in accordance with the use state or running state of the vehicle. For example, the vehicle height adjusting device described in Patent Document 1 makes it easy to get on and off by lowering the vehicle height when a passenger gets on and off. Also, when loading / unloading a load, the vehicle height is adjusted so that the height of the platform and the height of the loading platform coincide with each other so that the loading / unloading of the load can be performed easily. Further, the vehicle height adjusting device is configured to acquire vehicle speed information when traveling starts and to return to a vehicle height suitable for the traveling. Furthermore, a configuration is disclosed in which the vehicle height adjusting device can automatically return the vehicle height adjusting device to the reference value when the speed information is not appropriate.
JP-A-2005-29026

  However, there may be a problem if the vehicle height is returned to the reference value because the speed information is not appropriate. For example, some vehicles such as sports multipurpose vehicles (referred to as SUVs) are equipped with a vehicle height adjusting device so that rough roads such as uneven roads can be smoothly traveled. A vehicle equipped with a vehicle height adjustment device, when traveling on uneven roads, raises the vehicle height above the reference vehicle height so that the lower part of the vehicle body comes into contact with the uneven road surface. It prevents it from becoming impossible. If the speed information is not appropriate while traveling on such a rough road and the vehicle height is returned to the reference vehicle height, the lower portion of the vehicle body may come into contact with the road surface. In other words, there are cases where the vehicle cannot travel despite being controlled to the safe side during a failure.

  The present invention has been made in view of such circumstances, and its purpose is to enable appropriate vehicle height control according to the road surface condition when a failure occurs in the vehicle height adjusting device, particularly when the speed information is not appropriate. An object of the present invention is to provide a vehicle height adjustment device.

  In order to solve the above-described problems, a vehicle height adjustment device according to the present invention is disposed between an axle that supports each wheel of a vehicle and a vehicle body, and adjusts the vehicle height for changing the vehicle height of the vehicle for each wheel. A vehicle height detecting means for detecting a vehicle height value at each wheel mounting position, a speed acquiring means for acquiring speed information of the vehicle, and a vehicle height adjusting means for controlling the vehicle height adjustment. Vehicle height control means for executing, system abnormality detection means for detecting a system abnormality of a system that performs vehicle height adjustment, speed abnormality detection means for detecting speed acquisition abnormality of the speed acquisition means, Road surface estimation means for estimating a road surface state where the vehicle exists based on a comparison of vehicle height values of the wheels when a system abnormality and a speed acquisition abnormality are detected, and the road surface state is a predetermined bad road state If calmer, And return control means for returning the vehicle height to the reference vehicle height by driving the serial vehicle height adjustment means, characterized in that it comprises a.

  The vehicle height adjusting means only needs to be able to adjust the vehicle height for each wheel. For example, a device using air pressure, a device using hydraulic pressure, a device using a motor, or the like can be used. The speed acquisition means only needs to be able to determine whether or not the vehicle is traveling at a predetermined speed, for example, 30 km / h or more, and the speed information may be acquired based on information from the wheel speed sensor or used in other systems. Speed information may be obtained. The vehicle height control means, when the system of the vehicle height adjustment device is functioning normally, changes the vehicle state based on the operation information input from the operation unit operated by the driver and the speed information acquired by the speed acquisition means. The vehicle height adjusting means is controlled so as to achieve a suitable vehicle height. For example, when the vehicle is stopped, the vehicle height is adjusted according to the driver's request. In addition, the vehicle travels at a predetermined speed or higher (for example, 30 km / h or higher) in a state where the height adjustment is higher than the reference height or the low height adjustment is lower than the reference height. When started, it is considered that the driver has started traveling on a road surface that is easy to travel. Therefore, the vehicle height adjusting device estimates that the vehicle is traveling on a road surface that is easy to travel, and returns it to the reference vehicle height. The reference vehicle height is a vehicle height that can be determined at the vehicle design stage, and is a vehicle height that can realize stable traveling in consideration of air resistance during traveling and the position of the center of gravity of the vehicle. On the other hand, the system abnormality detection means detects an abnormality in the hardware aspect of the system and an abnormality in the software aspect. For example, a signal line open / short, sensor abnormality, software error that processes acquired information, etc. are detected as a system abnormality. The speed abnormality detecting means detects whether the speed acquired by the speed acquiring means is normally acquired. In general, a driver travels slowly when traveling on a rough road surface or when an obstacle that affects traveling is present around the vehicle. Therefore, when traveling at a speed less than a predetermined speed, for example, less than 30 km / h, it can be estimated that there is a possibility of a rough road or an obstacle around the road. In other words, if the speed information can be acquired normally, the surrounding environment of the vehicle can be estimated, and even if a failure occurs in a part of the system of the vehicle height adjustment device, vehicle height adjustment is limited when driving on rough roads or when there are obstacles. Thus, it is possible to control to prevent the vehicle height from being inadvertently changed. On the other hand, if a failure occurs in a part of the system and the speed information cannot be acquired normally, the vehicle height control as described above cannot be performed. Therefore, the road surface estimation means estimates the torsion of the contact points of the four wheels, that is, the plane state of the road surface on which the vehicle exists, by comparing the vehicle height values of the wheels. When the system abnormality and the speed acquisition abnormality are detected, when the estimation result of the road surface estimation means is gentler than a predetermined bad road state, the return control means is that the vehicle is running on a substantially flat road surface. presume. That is, it is estimated that the vehicle can travel without contacting the lower surface of the vehicle with the road surface even at the reference vehicle height, and the vehicle height is returned to the reference vehicle height so that the vehicle height is most suitable when the vehicle is traveling.

  In the above aspect, the road surface estimation means may estimate a road surface state based on a comparison of vehicle height values of wheels disposed on a diagonal line of the vehicle. According to this aspect, the torsional state of the road surface on which the vehicle is present can be estimated. As a result, it can be accurately determined whether or not the vehicle height can be returned to the reference vehicle height.

  The said aspect WHEREIN: The said road surface estimation means may acquire the acceleration of a wheel up-down direction further, and may estimate the state of a road surface based on the change of the said acceleration. For example, when the road surface is such that the rough road state and the non-bad road state (good road) change frequently, the road surface state is estimated based on only the change in vehicle height and the road is estimated to be a good road depending on the timing of estimation. There is. Therefore, referring to the acceleration in the vertical direction of the wheel, it is estimated that the road is bad when the change in vertical acceleration is larger than a predetermined value, and that the road is good when the change is lower than the predetermined value. According to this aspect, it is possible to improve the accuracy of estimation of the road surface state.

  According to the vehicle height adjusting device of the present invention, when a failure occurs in the vehicle height adjusting device, proper vehicle height control is performed in consideration of fail-safe according to the road surface condition even when the speed information cannot be normally acquired. it can.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  The vehicle height adjustment device according to the present embodiment enables appropriate vehicle height control according to the road surface state even when a failure occurs in the vehicle height adjustment device, particularly when speed information cannot be acquired normally. When the speed information cannot be acquired normally, the vehicle height adjusting device of the present embodiment estimates the road surface state based on comparison of vehicle height values at each wheel position. In other words, when the difference in vehicle height between the wheels exceeds a predetermined value, there are rough roads that are rougher than the predetermined level on the road surface, or there is a soft part even if it is apparently flat, and the wheels are dive on the road surface. It is estimated that. Conversely, when the difference in vehicle height value is small, it is estimated that the road surface is generally flat and the lower part of the vehicle can travel without contacting the road surface. In this way, if it can be estimated that the vehicle height adjustment system will not hinder driving even when a failure occurs in the system, that is, if it can be estimated that the vehicle is currently on a substantially flat road surface, the vehicle height is determined as the reference vehicle height. To ensure the running stability.

  FIG. 1 is a conceptual diagram of a configuration of a vehicle 10 on which the vehicle height adjusting device of the present embodiment is mounted. FIG. 1 shows only the configuration related to the vehicle height adjusting device of the present embodiment, and other configurations are omitted. In the present embodiment, as a vehicle height adjusting means for changing the vehicle height at the position of each wheel, for example, an electronically controlled air suspension or an absorber unit with a vehicle height adjusting function included in a hydraulic suspension can be used. Moreover, what performs vehicle height adjustment by motor drive can be included. In the present embodiment, a case where an electronically controlled air suspension absorber unit 12 is used in the vehicle height adjusting device will be described.

  A well-known absorber unit 12 that functions as vehicle height adjusting means can be used. For example, air is taken in and out of a chamber formed in the absorber unit 12, and the amount of expansion and contraction of the absorber unit 12 is adjusted to increase the vehicle height. What can be changed can be used. The absorber unit 12 is a part of a suspension that supports the wheel 14 at both ends in the vehicle width direction of the vehicle, and the lower end portion of the absorber unit 12 is connected to the suspension arm 16 (wheel 14 side). Moreover, the upper end part of the absorber unit 12 is connected to the vehicle body side (not shown). Therefore, even if the vehicle receives vibrations or shocks from the road surface while traveling, the vibrations and shocks are absorbed by the vibration damping effect of the absorber unit 12, thereby contributing to improvement in riding comfort and driving stability. In addition, as described above, the expansion and contraction of the absorber unit 12 itself can be executed by taking air into and out of the chamber of the absorber unit 12, and the vehicle height can be changed by adjusting the vertical distance between the vehicle body and the wheel 14. Can be made.

  The expansion / contraction operation of the absorber unit 12 is performed based on a vehicle height value detected by a vehicle height sensor 18 that is connected to a suspension arm 16 (such as a lower arm) constituting a suspension and functions as vehicle height detection means. For example, when the loading capacity or the number of passengers of the vehicle 10 changes, the vehicle height changes depending on the weight. At this time, if the absorber unit 12 is controlled, the vehicle height can be controlled to a substantially constant height. As a result, the vehicle posture is stabilized and the sprung resonance frequency can be maintained almost constant, which contributes to a comfortable ride and stability of operability. In addition, the vehicle height can be changed according to the vehicle speed, and stable running is realized at a vehicle height suitable for the vehicle speed. In addition, it is easy to get on and off by lowering the vehicle height when the passenger gets on and off. Moreover, if the height of the loading platform is adjusted for loading and unloading, the work becomes easy.

  A compressor 22 and a low pressure tank 24 are connected to the absorber unit 12 via a pipe 20. The compressor 22 generates compressed air that is fed into the chamber of the absorber unit 12 at a high speed in order to raise the vehicle height. The low-pressure tank 24 is used for extracting air from the chamber of the absorber unit 12 at high speed in order to lower the vehicle height. A control valve 26 is disposed on the pipe 20 for each absorber unit 12. The control valve 26 is controlled to be opened and closed by an ECU 28 that functions as a control unit that controls the entire vehicle height adjusting device. Further, the ECU 28 also performs an operation of contacting and separating the compressor 22 and the low-pressure tank 24 from the absorber unit 12 (pipe 20). The ECU 28 performs control of the control valve 26 by feedback control based on vehicle height data provided from the vehicle height sensor 18. Therefore, by detecting the height state of the suspension arm 16 with respect to the vehicle body by the vehicle height sensor 18, the vehicle height control can be realized by making the absorber unit 12 in an optimal expansion / contraction state.

  The ECU 28 is provided with various information necessary for executing the vehicle height adjustment. For example, the vehicle height value at each wheel position is acquired from the vehicle height sensor 18. Further, a wheel speed sensor 30 for measuring the wheel speed of the wheel 14 is arranged in the vicinity of each wheel 14 and always provides wheel speed information to the ECU 28. The ECU 28 acquires the vehicle speed of the vehicle 10 based on the wheel speed information. The ECU 28 may acquire wheel speed information and vehicle speed information used in a system other than the vehicle height control device and use it for vehicle height control. The ECU 28 is connected to a vehicle height adjustment switch 32 that is operated when the driver manually performs vehicle height adjustment. The vehicle height adjustment switch 32 is basically operable only when the vehicle 10 is stopped. The ECU 28 may accept an operation signal from the vehicle height adjustment switch 32 only when the vehicle 10 is stopped. Further, the ECU 28 is connected to a presentation device 34 that presents a vehicle height adjustment state and alarm information when the system fails. The presentation device 34 can include a display and a speaker.

  FIG. 2 is an explanatory diagram illustrating an example of the vehicle height sensor 18 that can be used in the present embodiment. The sensor body 18a is fixed to a part of the vehicle body via the bracket 36. A link arm 38 is connected to the arm 18b extended from the sensor body 18a via a ball joint or the like. The other end of the link arm 38 is fixed to a portion that moves up and down integrally with the wheel 14 such as the suspension arm 16 via a ball joint or the like. In the case of FIG. 2, the sensor body 18a detects the vehicle height value between the highest vehicle height position b and the lowest vehicle height position c around the neutral position a of the arm 18b. In the case of FIG. 2, the neutral position a can be set as the reference vehicle height.

  FIG. 3 is a block diagram illustrating the configuration of the ECU 28. In the present embodiment, the ECU 28 includes a system management unit 40, a vehicle speed acquisition unit 42, a vehicle height acquisition unit 44, a vehicle height control unit 46, a warp calculation unit 48, a fail return instruction unit 50, an alarm processing unit 52, and an acceleration acquisition unit 54. Etc.

  The system management unit 40 manages whether the vehicle height adjusting device is functioning normally. The vehicle height adjusting device normally operates in response to a signal from the vehicle height adjusting switch 32 operated by the user. As described above, when it is preferable to lower the vehicle height in order to get on and off the vehicle 10, or when the vehicle roof may come into contact with the gate, tunnel, garage ceiling, or the like at the reference vehicle height, The vehicle height adjustment switch 32 is operated to the lower side so that the vehicle height is lower than the reference vehicle height. Also, if it is easier to work if the height of the loading platform is raised according to the platform height, such as loading and unloading luggage, or if it is easier to drive if the vehicle height is high due to rough roads, etc. Operates the vehicle height adjustment switch 32 to the upward side to raise the vehicle height above the reference vehicle height. The reference vehicle height here is a vehicle height that can be determined at the vehicle design stage, and is suitable for stable and smooth travel of the vehicle in consideration of air resistance during travel and the center of gravity of the vehicle. The vehicle height can be expressed as the stable vehicle height. For example, when the vehicle speed is equal to or higher than a predetermined speed (for example, 30 km / h or higher), the vehicle 10 can be made to travel stably by running at the reference vehicle height.

  The system management unit 40 acquires the vehicle speed via the vehicle speed acquisition unit 42. The vehicle speed acquisition unit 42 functions as a speed acquisition unit, and may calculate the vehicle speed based on the wheel speed information from the wheel speed sensor 30, or may determine the wheel speed or vehicle speed detected by another system, for example, an ABS system. It may be obtained and used for vehicle height control. The vehicle height acquisition unit 44 may adopt the actual measurement value sent from the vehicle height sensor 18 as it is, or use the average value of vehicle height values that can be acquired in a predetermined period as the vehicle height value for control for vehicle height control. Also good.

  The system management unit 40 includes a system abnormality detection unit 56 that functions as a system abnormality detection unit and a speed abnormality detection unit 58 that functions as a speed abnormality detection unit. The system abnormality detection unit 56 detects a hardware abnormality or a software abnormality of the vehicle height control system. For example, signal line open / short, sensor abnormality, and software error that processes acquired information are detected as system abnormality. Further, the speed abnormality detection unit 58 detects whether the speed acquired by the vehicle speed acquisition unit 42 is normally acquired. For example, the wheel speed sensor 30 outputs continuous wheel speed information when the vehicle 10 is traveling. Further, when the vehicle 10 travels, the vehicle height sensor 18 always drives the absorber unit 12 to maintain the vehicle height at a predetermined vehicle height, and thus continuously outputs a subtle change in vehicle height value. When an operation signal is received from the vehicle height adjustment switch 32, the control valve 26 is controlled to open and close, and the compressor 22 and the low-pressure tank 24 are controlled to contact and separate from the pipe 20. The system abnormality detection unit 56 and the speed abnormality detection unit 58 can detect the signal values associated with these controls without deviating from the setting range at the timing at which the signal values should be detected, or can execute operations corresponding to the control commands. Anomaly detection based on whether or not

  When no abnormality is detected in the system abnormality detection unit 56 and the speed abnormality detection unit 58, the system management unit 40 performs control based on the operation of the vehicle height adjustment switch 32 via the vehicle height control unit 46 that functions as vehicle height control means. Vehicle height return control is executed when the vehicle speed exceeds a predetermined normal speed. That is, when the vehicle height control unit 46 performs opening / closing control of each control valve 26 and performs control based on the operation of the vehicle height adjustment switch 32 or starts running in the vehicle height adjustment state, the vehicle height based on the speed information. Perform return control.

  On the other hand, when an abnormality is detected by the system abnormality detection unit 56, but no abnormality is detected by the speed abnormality detection unit 58, that is, when the speed information can be acquired normally, the system management unit 40 performs a failure return instruction unit. 50 is notified that the system is currently in an abnormal state. When the system abnormality has occurred, the system management unit 40 can prohibit the operation from the vehicle height adjustment switch 32. However, as described above, if the speed information can be obtained accurately, when the vehicle is traveling at a speed lower than the predetermined speed, the road surface is a rough road exceeding a predetermined level, or the vehicle 10 is obstructed to travel around. It can be estimated that there is an obstacle. Further, when traveling at a predetermined speed or higher, it can be estimated that the road is a good road. Therefore, the fail return instruction unit 50 functioning as a return control means returns to the reference vehicle height when the vehicle 10 starts traveling at a predetermined speed or higher and the vehicle height is controlled to a state other than the reference vehicle height. The return process at the time of failure is executed as described above. Further, the fail return instruction unit 50 notifies the alarm processing unit 52 that a system abnormality has occurred. The alarm processing unit 52 notifies the vehicle height adjustment device that the vehicle height adjustment device has failed through the presentation device 34, but can return to the reference vehicle height based on the vehicle speed, or requires immediate maintenance. To the driver. This notification can be a voice notification, a character notification, a warning light, or the like.

  On the other hand, when an abnormality is detected by the system abnormality detection unit 56 and the speed abnormality detection unit 58, the system management unit 40 notifies the warp calculation unit 48 functioning as road surface estimation means that a speed abnormality has occurred. When receiving the notification of speed acquisition abnormality, the warp calculation unit 48 estimates the state of the road surface on which the vehicle 10 exists based on the comparison of the vehicle height values of the wheels 14. Specifically, the sum of the vehicle height values of the two wheels 14 arranged on the diagonal line of the vehicle 10 is obtained. Next, the difference between the vehicle height values of the two types of diagonal lines obtained is taken as a warp value. Based on the magnitude of the warp value, it can be estimated whether the vehicle 10 exists on a flat road surface or a twisted road surface. Specifically, the left front wheel height value is H [FL], the right front wheel height value is H [FR], the left rear wheel height value is H [RL], and the right rear wheel height value is H [RR]. In this case, the warp value Warp is Warp = (H [FL] + H [RR]) − (H [FR] + H [RL]). When the warp value Warp exceeds a predetermined value, for example, when it exceeds 30 to 40 mm, and preferably exceeds 30 mm, it can be estimated that the road surface is largely twisted in the diagonal direction of the vehicle 10. That is, if the vehicle 10 is in a twisted posture and the vehicle height is inadvertently returned to the reference vehicle height, the bottom of the vehicle 10 comes into contact with the road surface, and the driving force of the wheels 14 cannot be transmitted to the road surface, making it impossible to travel. There is sex. Conversely, when the warp value Warp is equal to or less than a predetermined value, it can be estimated that the road surface is substantially flat. That is, even if the vehicle height is returned to the reference vehicle height, the vehicle is not disabled, and the vehicle stability during traveling can be improved.

  In this case as well, the fail return instruction unit 50 notifies the alarm processing unit 52 that a system abnormality has occurred. The alarm processing unit 52 currently fails in the vehicle height adjustment device via the presentation device 34, but can return to the reference vehicle height based on the road surface condition, or perform maintenance immediately. Notify that is desirable.

  As described above, the warp calculation unit 48 calculates the warp value based on the vehicle height value acquired from the vehicle height acquisition unit 44, but in the case of a road surface in which unevenness changes frequently including a flat portion, the warp value is calculated. Depending on the calculation timing, there is a possibility that the calculation is performed in a flat portion, and the reliability of the warp value may be lowered. Therefore, the warp calculation unit 48 may acquire information from the acceleration sensor 60 that detects the acceleration in the vertical direction of the wheel 14 via the acceleration acquisition unit 54 to improve the determination accuracy of the bad road and the good road. When traveling on an uneven road, the wheel 14 repeatedly vibrates up and down. That is, the vertical acceleration change becomes intense. This change in acceleration may be detected, and it may be estimated that the vehicle is traveling on a rough road when acceleration fluctuations exceeding a predetermined threshold value occur. In this case, since a change in acceleration occurs from a flat road to an uneven road and vice versa, a bad road determination can be performed with high accuracy. Therefore, when the acceleration in the vertical direction of each wheel 14 is equal to or greater than a predetermined threshold value, it is estimated that the vehicle 10 is traveling on a highly uneven road surface. At this time, when the high vehicle height is adjusted, the fail return instruction unit 50 maintains the current vehicle height state in the same manner as when the warp value exceeds the predetermined value. Then, after the fail return instructing unit 50 can estimate that the change in acceleration is small and escapes a rough road (it has started running on a generally flat road), the vehicle height is changed to a reference vehicle height suitable for driving. Return.

  Further, whether or not the vehicle is traveling on an unpaved road can also be determined based on a change in acceleration in the vertical direction of each wheel 14. In the case of an unpaved road, the acceleration in the vertical direction of the wheel 14 shows a change pattern with a small amplitude and a short cycle. On the other hand, in the case of a paved road, the change in acceleration is smaller and shows a change pattern with a longer cycle. If the road is unpaved and the current vehicle height is high, it may be possible to enter a rough road with severe unevenness in the future, so it can be estimated that it is preferable not to return the vehicle height to the standard vehicle height. . Therefore, the fail return instructing unit 50 continues to maintain the current vehicle height until it escapes from the unpaved road, and executes vehicle height return control when it is determined that the vehicle has escaped from the unpaved road. Thus, by using the acceleration information in the vertical direction with respect to the wheel 14, it is possible to estimate a rough road with high accuracy and an unpaved road or a paved road. High traveling control can be executed.

  As described above, according to the vehicle height adjusting device of the present embodiment, even when a failure occurs in which the vehicle speed cannot be normally acquired, the vehicle height is returned to the reference vehicle height at an appropriate timing according to the road surface condition. Therefore, a good fail safe function can be secured.

  The operation of the vehicle height adjusting device configured as described above will be described with reference to the flowchart of FIG.

  When the ignition switch of the vehicle 10 is turned on, the system management unit 40 starts monitoring whether or not a failure has occurred in the system of the vehicle height adjusting device (Y or N in S100). When the system abnormality detection unit 56 and the speed abnormality detection unit 58 determine that no system abnormality has occurred (N in S100), the system management unit 40 executes normal vehicle height control processing via the vehicle height control unit 46. (S102). That is, the system management unit 40 permits manual vehicle height adjustment based on the vehicle height adjustment switch 32. When the vehicle 10 starts traveling at a predetermined speed or higher (for example, 20 to 30 km / h, preferably 30 km / h or higher) while being adjusted to a high vehicle height state or a low vehicle height state, the system management unit 40 It is estimated that the vehicle 10 is traveling on a substantially flat road surface. Then, the vehicle height is automatically returned to the reference vehicle height to ensure traveling stability, and the process returns to S100 to continue monitoring whether a system abnormality has occurred.

  In S100, when it is detected that a system abnormality has occurred in the vehicle height adjusting device (Y in S100), the system management unit 40 determines that the vehicle height of each wheel 14 is currently based on the information from the vehicle height acquisition unit 44. It is confirmed whether or not the reference vehicle height is reached (Y or N in S104). If all the wheels 14 of the vehicle 10 are currently controlled to the reference vehicle height (Y in S104), the system management unit 40 prohibits vehicle height adjustment by the vehicle height adjustment switch 32 (S106). Further, the system management unit 40 supplies an alarm generation signal to the alarm processing unit 52 and presents to the driver using the presentation device 34 that a system abnormality has occurred in the vehicle height adjusting device (S108). For example, encourage the driver to perform maintenance. And vehicle height adjustment control is complete | finished.

  In S104, if any of the wheels 14 does not reach the reference vehicle height (N in S104), the system management unit 40 uses the speed abnormality detection unit 58 to acquire speed information (vehicle speed information) normally. It is confirmed whether it is made (Y or N in S110). If the vehicle speed has been acquired normally (Y in S110), the system management unit 40 checks whether the relationship between the current vehicle speed and the threshold value is vehicle speed ≧ threshold value (Y or N in S112). . The threshold value in this case can be set to, for example, 20 to 30 km / h, and more preferably 30 km / h. When vehicle speed <threshold value (N in S112), it can be estimated that the vehicle 10 is intentionally traveling at a low speed. In other words, it can be estimated that the driver is traveling on a rough road having a predetermined unevenness or higher, or where there is an obstacle around the vehicle 10, for example, a place with a low roof or a gate. In this case, since it is not desirable to change the vehicle height of the vehicle 10 carelessly, the fail return instruction unit 50 instructs the vehicle height control unit 46 to maintain the vehicle height (S114). That is, when the vehicle height state is high, it is temporarily prohibited to return from the high vehicle height to the reference vehicle height. Further, when the vehicle height state is low, it is temporarily prohibited to return from the low vehicle height to the reference vehicle height. In this case, since the vehicle height adjustment device has successfully acquired the speed information, the vehicle height control based on the vehicle speed is possible. Therefore, if the obstacle to the travel (bad road or obstacle) is resolved, the reference vehicle height Can be automatically restored, but one of the systems has failed. Therefore, the fail return instructing unit 50 uses the alarm processing unit 52 and the presentation device 34 to notify the driver that a failure has occurred and that the reference vehicle height can be returned after the obstacle to the travel is resolved (S116). . After the failure notification, the vehicle 10 may exit the place where there is a rough road or an obstacle, and may start traveling at a predetermined speed or higher. Therefore, the system management unit 40 returns to S110 and continues the vehicle speed monitoring.

  On the other hand, if the vehicle speed is equal to or greater than the threshold value in S112 (Y in S112), it can be estimated that the vehicle 10 is not traveling on a place with a rough road or an obstacle. That is, even if the vehicle travels at a vehicle height suitable for the travel speed, the travel of the vehicle 10 is not hindered. Therefore, the fail return instruction unit 50 instructs the vehicle height control unit 46 to execute the vehicle height return process at the time of failure (S118). That is, the vehicle height control unit 46 controls the opening and closing of the control valve 26 and the absorber unit 12 is expanded and contracted to return the vehicle height to the reference vehicle height. That is, when the vehicle height state is high, the vehicle is returned from the high vehicle height to the reference vehicle height. When the vehicle height state is low, the vehicle is returned from the low vehicle height to the reference vehicle height. In this case, the vehicle height adjusting device can normally obtain the speed information, but a failure has occurred in any of the systems. Therefore, the fail return instruction unit 50 notifies the driver that the vehicle height has been returned to the reference vehicle height using the alarm processing unit 52 and the presentation device 34, but a failure has occurred (S120). And a series of vehicle height adjustment control is complete | finished. That is, the reference vehicle height is maintained, and the completion of the maintenance of the vehicle height adjusting device is awaited.

  In S110, when the speed abnormality detection unit 58 detects that the speed information cannot be acquired normally (N in S110), the system management unit 40 calculates a warp value based on the vehicle height value in each wheel 14 in the warp calculation unit 48. An instruction is issued (S122). For example, the speed abnormality detection unit 58 may not be able to acquire speed information despite traveling, or may acquire speed information that is not normal, or if a speed information error occurs in another system. For example, it is determined that the speed information cannot be acquired normally. The warp calculation unit 48 acquires the information of the vehicle height sensor 18 from the vehicle height acquisition unit 44 as described above, and warp value Warp = (H [FL] + H [RR]) − (H [FR] + H [RL] ) Is calculated. The warp calculation unit 48 provides the calculated warp value to the fail return instruction unit 50, and the fail return instruction unit 50 compares the calculated warp value with a predetermined threshold value (S124). As described above, the threshold value used for the comparison of the warp values can be set to 30 mm, for example. When the calculated warp value is warp value ≦ threshold value (30 mm) (Y in S124), the process proceeds to S118. That is, the difference in the sum of the vehicle height values of the two types of diagonal lines is small and the vehicle 10 is little twisted. Therefore, it can be estimated that the currently running road surface is generally flat. As a result, it can be estimated that the traveling of the vehicle 10 is not hindered even when traveling at a vehicle height suitable for the traveling speed. Therefore, the fail return instruction unit 50 instructs the vehicle height control unit 46 to execute the vehicle height return process at the time of failure (S118). That is, the vehicle height control unit 46 controls the opening and closing of the control valve 26 and the absorber unit 12 is expanded and contracted to return the vehicle height to the reference vehicle height. In addition, although it can be estimated that the road surface is substantially flat by the estimation using the warp value, the situation around the vehicle (for example, the situation of the obstacle around the vehicle or above) cannot be estimated. For this reason, in the vehicle height return processing when the warp value is used, it is desirable to perform only the return from the high vehicle height to the reference vehicle height. In this case as well, the vehicle height adjusting device controls the vehicle height to be suitable for stable travel in an emergency manner, although it has a failure in which speed information cannot be acquired normally. Therefore, the fail return instruction unit 50 notifies the driver that the vehicle height has been returned to the reference vehicle height using the alarm processing unit 52 and the presentation device 34, but a failure has occurred (S120). And a series of vehicle height adjustment control is complete | finished. That is, the reference vehicle height is maintained, and the completion of the maintenance of the vehicle height adjusting device is awaited.

  On the other hand, if the warp value is greater than the threshold value in S124 (N in S124), it can be estimated that the vehicle 10 is currently traveling on a rough road of a predetermined level or more with severe unevenness. In this case, since it is not desirable to change the vehicle height of the vehicle 10 carelessly, the fail return instruction unit 50 gives the vehicle height control unit 46 the vehicle height regardless of whether the current vehicle height is high or low. An instruction is given to maintain the current state (S126). That is, the return to the reference vehicle height is temporarily prohibited. In this case, the vehicle height adjusting device can control the vehicle height to be suitable for stable traveling in an emergency manner, although it has a failure in which speed information cannot be acquired normally. Therefore, the fail return instruction unit 50 notifies the driver that the vehicle height can be returned to the reference vehicle height using the alarm processing unit 52 and the presentation device 34, but a failure has occurred (S128). In fail notification, it is desirable to promptly get out of the rough road and perform maintenance of the vehicle 10. After completion of the notification, the process proceeds to S110 to prepare for control in which the vehicle 10 exits a rough road and returns the vehicle height to the reference vehicle height. In the case of the present embodiment, there may be a case where the speed information could not be temporarily acquired. Therefore, an example in which the flow after S128 is shifted to S110 has been described, but when the speed information cannot be normally acquired even once, The process may be resumed from the calculation of the warp value by shifting to S122.

  In the present embodiment, the warp calculation unit 48 calculates the warp value when the speed abnormality detection unit 58 cannot acquire the speed information normally. At this time, even if the vehicle 10 is traveling on a rough road, the state of severe unevenness does not always continue. In other words, even if it is a bad road, there may be repeated uneven portions or flat portions. At this time, depending on the calculation timing of the warp value, there is a case where the calculation is performed on a flat portion even though the vehicle is traveling on a bad road, and it is erroneously determined that the vehicle has shifted to a good road. Therefore, the warp calculation unit 48 calculates the warp value at a predetermined interval, for example, every 10 seconds, and further determines whether the vehicle travels on a bad road or on a good road based on the average value of 10 warp values. Good. In this case, the reliability of the bad road determination based on the warp value can be improved.

  Note that the configuration of the drawing used in this embodiment is an example, and when speed information cannot be acquired in the vehicle height control device, it is determined whether or not to return to the reference vehicle height based on the warp value based on the vehicle height value. If it is a thing, you may change suitably the structure of FIGS. 1-3 and the procedure of FIG. 4 for implement | achieving it. For example, in the present embodiment, an example in which the vehicle height adjustment is performed using an electronically controlled air suspension has been described, but a hydraulically controlled suspension may be used, and a motor drive controlled suspension may be similar to the present embodiment. An effect can be obtained. Further, in FIG. 3, in order to make the explanation easy to understand, the internal configuration of the ECU 28 is described separately for each function. However, if a similar function can be achieved, a plurality of functions may be integrated or further separated. The same effect as this embodiment can be obtained.

1 is a conceptual diagram of a configuration of a vehicle on which a vehicle height adjusting device according to an embodiment is mounted. It is explanatory drawing explaining an example of the vehicle height sensor which can be utilized for the vehicle height adjustment apparatus which concerns on this embodiment. It is a block diagram explaining the internal structure of ECU of the vehicle height adjustment apparatus which concerns on this embodiment. It is a flowchart explaining operation | movement of the vehicle height adjustment apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 vehicle, 12 absorber unit, 14 wheel, 16 suspension arm, 18 vehicle height sensor, 28 ECU, 30 wheel speed sensor, 32 vehicle height adjustment switch, 34 presentation apparatus, 40 system management part, 42 vehicle speed acquisition part, 44 vehicle height An acquisition unit, a 46 vehicle height control unit, a 48 warp calculation unit, a 50 fail return instruction unit, a 52 alarm processing unit, a 54 acceleration acquisition unit, a 56 system abnormality detection unit, a 58 speed abnormality detection unit, and a 60 acceleration sensor.

Claims (3)

A vehicle height adjusting means that is disposed between an axle that supports each wheel of the vehicle and the vehicle body, and that changes the vehicle height of the vehicle for each wheel;
Vehicle height detection means for detecting the vehicle height value at the mounting position of each wheel;
Speed acquisition means for acquiring speed information of the vehicle;
Vehicle height control means for controlling the vehicle height adjustment means to execute vehicle height adjustment;
A system abnormality detecting means for detecting a system abnormality of the system for adjusting the vehicle height;
A speed abnormality detection means for detecting a speed acquisition abnormality of the speed acquisition means;
Road surface estimation means for estimating a state of a road surface on which the vehicle exists based on a comparison of vehicle height values of the wheels when the system abnormality and speed acquisition abnormality are detected;
A return control means for driving the vehicle height adjusting means to return the vehicle height to a reference vehicle height when the road surface condition is gentler than a predetermined bad road condition;
A vehicle height adjusting device comprising:   2. The vehicle height adjusting device according to claim 1, wherein the road surface estimating means estimates a road surface state based on a comparison of vehicle height values of wheels arranged on a diagonal line of the vehicle.   The vehicle height adjusting device according to claim 1 or 2, wherein the road surface estimating means further acquires acceleration in a vertical direction of the wheel and estimates a road surface state based on a change in the acceleration.

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