Attenuation force control system

Abstract

To provide an attenuation force control system which can perform control to make attenuation force respond to speed of a vehicle, and can be easily installed on the vehicle.SOLUTION: An attenuation force control system S includes: an attenuation force control device 1 having a sensor unit 2 for detecting vibration of a vehicle body B of a vehicle V, a control unit 3 for controlling attenuation force of a shock absorber D which is provided between the vehicle body B and wheels W of the vehicle V and can adjust attenuation force on the basis of vibration information detected by the sensor unit 2, and a communication unit 5 which allows wireless communications; and a portable terminal 30 which allows wireless communications with the attenuation force control device 1, wherein the control unit 3 controls the shock absorber D on the basis of speed determined from a position detected by the portable terminal 30 or speed detected by the portable terminal 30.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a damping force control system. [Background technology]

[0002] Conventionally, shock absorbers with adjustable damping force are configured with a shock absorber body that is interposed between the sprung and unsprung members of a vehicle and expands and contracts, and a damping valve that provides resistance to the flow of fluid filled within the shock absorber body and is driven by a solenoid to adjust the generated damping force, with the solenoid being controlled by a damping force control device that is specialized for controlling shock absorbers installed in the vehicle.

[0003] In order to optimize the damping force of the shock absorber according to the vehicle's driving conditions, the damping force control device is equipped with sensors that obtain various information to recognize the driving conditions, such as the vehicle's speed, sprung acceleration, and unsprung acceleration, and a calculation device that calculates the damping force that the shock absorber should generate based on the information from the sensors, and supplies current to the solenoid of the damping valve so that the shock absorber generates the calculated damping force.

[0004] In addition, in such a system, the damping force control device outputs commands to a control unit that controls the solenoid of the shock absorber via a CAN bus, so that when controlling the damping force output to the shock absorber to be sensitive to the vehicle speed, the speed of the vehicle while it is traveling can be obtained from the vehicle (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-015541 Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, when the damping force control device controls the damping force of the shock absorber in response to the vehicle speed, it is necessary to connect it to a CAN bus. Therefore, when the damping force control device is not originally attached to the vehicle and the user installs the damping force control device in the vehicle, that is, when the damping force control device is retrofitted, installing the damping force control device in the vehicle is an extremely tedious task.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a damping force control system that can control damping force in response to vehicle speed and that can be easily installed on a vehicle. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the damping force control system of the present invention comprises a sensor unit that detects vibrations of the vehicle body, a control unit that controls the damping force of an adjustable damping shock absorber installed between the vehicle body and the wheels based on vibration information detected by the sensor unit, a damping force control device having a communication unit capable of wireless communication, and a mobile terminal that can communicate with the damping force control device, and the control unit controls the shock absorber based on the speed determined from the position detected by the mobile terminal or the speed detected by the mobile terminal.

[0009] According to the damping force control system configured in this manner, the damping force control device can obtain the vehicle position or vehicle speed from the mobile terminal, and can control the damping force of the shock absorber in response to the vehicle speed without being connected to the CAN bus in the vehicle.Therefore, even when the damping force control device is retrofitted to the vehicle, the damping force control device can be easily installed on the vehicle, and the installation work is also simple.

[0010] In addition, the sensor unit in the damping force control system may be capable of detecting the acceleration of the vehicle body in the longitudinal direction, and when the position or speed cannot be obtained from the mobile terminal, the control unit may determine the speed of the vehicle V from the acceleration of the vehicle body in the longitudinal direction detected by the sensor unit, and control the shock absorber based on the determined speed.

[0011] With the damping force control system configured in this manner, even if the position or speed cannot be obtained from the mobile terminal, the vehicle speed can be seamlessly determined and control that makes the shock absorber damping force sensitive to speed can be continued. [Effects of the Invention]

[0012] As described above, the damping force control system of the present invention can control the damping force in response to the vehicle speed, and can be easily installed on the vehicle. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a damping force control system and a damping force control device according to an embodiment applied to a vehicle; [Figure 2] FIG. 2 is a schematic cross-sectional view of a shock absorber. [Figure 3] 1 is a diagram illustrating a configuration of a damping force control device according to an embodiment. [Figure 4] FIG. 2 is a diagram showing a configuration of a current control unit in the damping force control device. [Figure 5] FIG. 2 is a diagram illustrating a configuration of a mobile terminal in the damping force control system according to the embodiment. [Figure 6] 4 is a flowchart showing a processing procedure for controlling the damping force of a damping force control device in a damping force control system according to an embodiment. [Figure 7] 4 is a flowchart showing a processing procedure for determining the vehicle speed of the damping force control device in the damping force control system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below based on the embodiments shown in the drawings. As shown in Fig. 1, a damping force control device 1 in one embodiment is configured to include a sensor unit 2 that detects vibrations at predetermined positions on a body B of a vehicle V, a control unit 3 that controls the damping force of an adjustable shock absorber D provided between the body B and wheels W of the vehicle V based on vibration information detected by the sensor unit 2, and a communication unit 5 that can wirelessly communicate with a mobile terminal 30. A damping force control system S in one embodiment is configured to include the damping force control device 1 and the mobile terminal 30. The damping force control device 1 in this embodiment controls four shock absorbers D that are respectively interposed between the body B of the vehicle V and the front, rear, left, and right wheels W of the vehicle body B.

[0015] First, we will explain the shock absorber D that is the object to be controlled by the damping force control device 1. As shown in Fig. 2, the shock absorber D includes a cylindrical cylinder 6, a piston 7 slidably inserted into the cylinder 6, a rod 8 inserted into the cylinder 6 so as to be axially movable and connected to the piston 7, an extension-side chamber R1 and a compression-side chamber R2 that are partitioned by the piston 7 within the cylinder 6 and filled with a liquid such as hydraulic oil, an intermediate cylinder 9 that covers the outer periphery of the cylinder 6 and forms an annular gap between it and the cylinder 6, and an outer cylinder 10 that covers the outer periphery of the intermediate cylinder 9 and forms an annular reservoir R that is filled with gas and liquid between it and the intermediate cylinder 9. The shock absorber D is provided with: a rectifying passage 11 that communicates between the expansion-side chamber R1 and the compression-side chamber R2 and allows only the flow of liquid from the compression-side chamber R2 to the expansion-side chamber R1 with almost no resistance; a suction passage 12 that communicates between the compression-side chamber R2 and the reservoir R and allows the flow of liquid from the reservoir R to the compression-side chamber R2 with almost no resistance; a damping passage 13 that communicates between the expansion-side chamber R1 and the reservoir R via a gap between the cylinder 6 and the intermediate tube 9; and a damping force adjusting unit 15 that can adjust the damping force generated by the shock absorber D in response to a command from the damping force control device 1.

[0016] In this embodiment, the damping force adjusting section 15 is a solenoid valve provided midway through the damping passage 13 .

[0017] As shown in the figure, the damping force adjustment unit 15 is configured to include, for example, a valve body 15a provided midway through the damping passage 13, a spring 15b that biases the valve body 15a so as to block the damping passage 13, and a solenoid 15c that generates a thrust force that counteracts the spring 15b when current is applied, and the valve opening pressure can be changed according to the amount of current supplied to the solenoid 15c.

[0018] When the pressure in the extension-side chamber R1 upstream of the damping passage 13 acting on the valve body 15a exceeds the relief pressure (valve-opening pressure) of the damping force adjustment unit 15, this pressure and the force of the solenoid 15c pressing on the valve body 15a overcome the force of the spring 15b biasing the valve body 15a, and the valve body 15a compresses the spring 15b, causing the damping force adjustment unit 15 to open the damping passage 13.

[0019] Furthermore, in the damping force adjusting unit 15, increasing the amount of current supplied to the solenoid 15c increases the thrust generated by the solenoid 15c. Therefore, when the amount of current supplied to the solenoid 15c is maximized, the valve-opening pressure in the damping force adjusting unit 15 is minimized, and conversely, when no current is supplied to the solenoid 15c at all, the valve-opening pressure in the damping force adjusting unit 15 is maximized. Note that the damping force adjusting unit 15 may be configured to maximize the valve-opening pressure when the amount of current to the solenoid 15c is maximized.

[0020] Although the damping force adjusting unit 15 is capable of adjusting the valve opening pressure as described above, it may also be capable of adjusting the flow path area by applying thrust generated by the solenoid 15c to the valve element 15a. As described above, the damping force adjusting unit 15 is only required to be able to adjust the damping force generated by the shock absorber D by changing the resistance to the flow of liquid passing through the damping passage 13 in response to a command from the damping force control device 1. Therefore, instead of a solenoid valve, the damping force adjusting unit 15 may be a valve using a stepping motor, or, if the liquid filled in the shock absorber D is an electrorheological fluid, a magnetorheological fluid, or an electromagnetic rheological fluid, it may be provided with a device that applies an electric field or a magnetic field to the liquid passing through the damping passage 13 to adjust the resistance to the flow of liquid passing through the damping passage 13. Furthermore, the damping force adjusting unit 15 may be capable of adjusting the damping force during extension and compression of the shock absorber D, or may be capable of adjusting the damping force during either extension or compression.

[0021] In the shock absorber D configured as described above, during an extension operation of the shock absorber D in which the rod 8 moves upward in FIG. 2 relative to the cylinder 6, liquid moves from the extension-side chamber R1, which is compressed by the piston 7 rising in the cylinder 6, to the reservoir R via the damping passage 13 and the damping force adjustment unit 15. Therefore, the pressure in the extension-side chamber R1 rises and becomes equal to the valve-opening pressure of the damping force adjustment unit 15. Furthermore, during an extension operation of the shock absorber D, liquid is supplied from the reservoir R via the suction passage 12 to the compression-side chamber R2, whose volume is expanded by the piston 7 rising in the cylinder 6, so that the pressure in the compression-side chamber R2 becomes approximately equal to the pressure in the reservoir R. Therefore, the pressure in the extension-side chamber R1 becomes higher than the pressure in the compression-side chamber R2 by the valve-opening pressure of the damping force adjustment unit 15, and the shock absorber D generates a damping force that hinders the extension operation. Since the valve opening pressure of the damping force adjusting section 15 changes depending on the amount of current supplied to the solenoid 15c, the damping force during the expansion operation of the shock absorber D can be adjusted according to the amount of current supplied to the solenoid 15c.

[0022] On the other hand, when the shock absorber D is contracting and the rod 8 moves downward in FIG. 2 relative to the cylinder 6, liquid moves from the compression-side chamber R2, which is compressed by the piston 7 moving downward in the cylinder 6, to the expanding extension-side chamber R1 via the rectification passage 11. When the shock absorber D is contracting, an excess of liquid corresponding to the volume of the rod 8 entering the cylinder 6 is created inside the cylinder 6, and the excess liquid is discharged from the cylinder 6 to the reservoir R via the damping passage 13 and the damping force adjuster 15. Therefore, the pressures in the extension-side chamber R1 and the compression-side chamber R2 in the cylinder 6 both rise and become equal to the valve opening pressure of the damping force adjuster 15, but because the pressure-receiving area of ​​the piston 7 facing the compression-side chamber R2 is larger than the pressure-receiving area of ​​the piston 7 facing the extension-side chamber R1 by the cross-sectional area of ​​the rod 8, the shock absorber D generates a damping force that suppresses contraction. Since the valve opening pressure of the damping force adjusting section 15 changes depending on the amount of current supplied to the solenoid 15c, the damping force during the contraction operation of the shock absorber D can be adjusted according to the amount of current supplied to the solenoid 15c.

[0023] The configuration of the shock absorber D is merely an example and is not limited to the above configuration. Any configuration may be used as long as the damping force adjuster 15 is capable of generating a damping force that applies resistance to the flow of liquid and prevents the extension and contraction of the shock absorber D. Therefore, the shock absorber D of this embodiment is configured as a uniflow type that includes a reservoir R and in which liquid circulates one-way through the expansion-side chamber R1, the compression-side chamber R2, and the reservoir R in that order. However, the shock absorber D may be configured as a biflow type in which liquid flows back and forth between the expansion-side chamber R1 and the compression-side chamber R2 during expansion and contraction. When the shock absorber D is configured as a biflow type, if a damping passage connecting the expansion-side chamber R1 and the compression-side chamber R2 allows liquid to flow from the expansion-side chamber R1 to the compression-side chamber R2 and liquid to flow from the compression-side chamber R2 to the expansion-side chamber R1, a damping force adjuster may be provided in the damping passage. Furthermore, when the shock absorber D is configured as a bi-flow type and is provided with an extension side damping passage that allows liquid to flow only from the extension side chamber R1 to the compression side chamber R2 and a compression side damping passage that allows liquid to flow only from the compression side chamber R2 to the extension side chamber R1, a damping force adjusting device may be provided in both the extension side damping passage and the compression side damping passage, or a damping force adjusting device may be provided in only one of the extension side damping passage and the compression side damping passage.

[0024] The shock absorber D configured in this manner is interposed between the vehicle body B and the wheel W of the vehicle V, with the cylinder 6 attached to a knuckle or suspension arm that holds the wheel W and connected to the wheel W as an unsprung member, and the rod 8 connected to the vehicle body B as a sprung member. The shock absorber D expands and contracts due to vibrations input from the road surface while the vehicle V is traveling, generating a damping force that suppresses vibrations of the vehicle body B.

[0025] Next, the damping force control device 1 will be described. As shown in Fig. 3, the damping force control device 1 includes a sensor unit 2 that detects vibrations of a vehicle body B of a vehicle V, a control unit 3 that calculates a target damping force based on vibration information detected by the sensor unit 2, a current control unit 16 that controls the current supplied to a damping force adjusting unit 15 in a shock absorber D based on the target damping force calculated by the control unit 3, and a communication unit 5 that can wirelessly communicate with a mobile terminal 30. In addition, in the damping force control device 1 of this embodiment, the sensor unit 2, the control unit 3, the communication unit 5, and the current control unit 16 are housed in a single housing 20, and the housing 20 is installed in the passenger compartment of the vehicle V.

[0026] Each component of the damping force control device 1 will be described in detail below. In this embodiment, the sensor unit 2 is an inertial measurement device that detects angular velocities around the three axes of the vehicle body B (front-rear, left-right, and up-down), i.e., three angular velocities in the roll direction, pitch direction, and yaw direction of the vehicle body B, and accelerations around the three axes of the vehicle body B (front-rear, left-right, and up-down), as vibration information at a predetermined position of the vehicle body B. The sensor unit 2 is housed in a housing 20 and installed on the vehicle body B together with the housing 20. Note that it is sufficient for the sensor unit 2 to detect vibration information of the vehicle body B required for the damping force control device 1 to control the damping force. Therefore, for example, if the damping force control device 1 requires only the acceleration of the vehicle body B in the up-down direction, the sensor unit 2 may detect only the acceleration of the vehicle body B in the up-down direction. Furthermore, although the sensor unit 2 is housed in the housing 20 in the damping force control device 1 of this embodiment, it may also be installed on the vehicle body B separately from the housing 20.

[0027] The housing 20 is box-shaped and houses the sensor unit 2, the control unit 3, and the communication unit 5 inside. Although not shown, the characters "front" and "rear" are displayed near two opposing sides in the front-to-rear direction of the rectangular top surface of the housing 20, and the characters "right" and "left" are displayed near two opposing sides in the left-to-right direction of the rectangular top surface. The sensor unit 2 is housed in the housing 20 so that the detection axis of acceleration in the front-to-rear direction coincides with the front-to-rear direction of the housing 20, the detection axis of acceleration in the left-to-right direction coincides with the left-to-right direction of the housing 20, the detection axis of acceleration in the up-to-down direction coincides with the up-to-down direction of the housing 20, the direction of the detected roll angular velocity coincides with the direction of rotation about the front-to-rear direction of the housing 20 as an axis, the direction of the detected pitch angular velocity coincides with the direction of rotation about the left-to-right direction of the housing 20 as an axis, and the direction of the detected yaw angular velocity coincides with the direction of rotation about the up-to-down direction of the housing 20 as an axis.

[0028] Therefore, when a user of the damping force control device 1 installs the housing 20 near the center of the vehicle body inside the vehicle cabin, relying on the indications of "front," "rear," "left," and "right" on the top surface of the housing 20, and aligns the front, rear, left, right, and top and bottom of the housing 20 with the front, rear, left, right, and top and bottom of the vehicle body B, the sensor unit 2 can detect three angular velocities in the roll direction, pitch direction, and yaw direction at the installation position where the housing 20 is installed relative to the vehicle body B, and accelerations along the three axes of the front, rear, left, right, and top and bottom of the vehicle body B. In reality, the installation position of the sensor unit 2 may not coincide with a predetermined position on the vehicle body B, and the installation posture of the sensor unit 2 may not be horizontal when the vehicle V is stopped on a horizontal road surface. In this case, the angular velocities and accelerations detected by the sensor unit 2 may be corrected by calibration so that they coincide with the angular velocities and accelerations at the actual predetermined position of the vehicle body B. In the damping force control device 1 of this embodiment, the predetermined position of the sensor unit 2 is the center of gravity of the vehicle body B, and is calibrated so as to be able to detect the three-axial angular velocity and three-axial acceleration at the center of gravity of the vehicle body B. In the damping force control device 1 of this embodiment, the sensor unit 2 is configured to detect the angular velocity and acceleration at the center of gravity of the vehicle body B in order to control the damping force of the shock absorbers D installed on each of the four wheels, grasp the overall vibration of the vehicle body B, and suppress the vibration of the vehicle body B; however, the predetermined position may be set at a position other than the center of gravity as long as it is suitable for control by the damping force control device 1.

[0029] The indication of front, rear, left, and right displayed on the housing 20 may be affixed by engraving, pasting a piece of paper indicating the front, rear, left, and right, printing, or the like. If the housing 20 is manufactured by injection molding or the like using synthetic resin, the characters for front, rear, left, and right may be formed using a mold. Since it is sufficient to identify the front, rear, left, and right of the housing 20, only one of the characters for front, rear, left, and right may be displayed instead of all the characters for front, rear, left, and right. Symbols or numbers may be displayed instead of the characters for front, rear, left, and right. If the shape of the housing 20 allows for the identification of front, rear, left, right, and up and down, the indication of characters or symbols may be omitted. The indication on the housing 20 may be omitted because the angular velocities and accelerations detected by the sensor unit 2 are corrected by the calibration. However, it is preferable to indicate the indication on the housing 20 because, when the user installs the housing 20 in the direction of the vehicle body B according to the indication, the detection axis of the sensor unit 2 roughly coincides with the front, rear, left, right, and up and down of the vehicle body B.

[0030] The communication unit 5 is equipped with an antenna unit (not shown) and is capable of two-way communication with the mobile terminal 30. In this embodiment, wireless communication conforming to the IEEE802.15 standard is performed, but as long as communication with the mobile terminal 30 is possible, in addition to wireless communication conforming to the above standard, wireless LAN (Local Area Network) communication conforming to the IEEE802.11 standard may also be performed.

[0031] 5, the mobile terminal 30 is a highly portable terminal such as a smartphone or tablet PC, and includes an inertial measurement unit 30b housed in a housing 30a and capable of detecting triaxial angular velocity and triaxial acceleration, a touch panel 30c mounted on the housing 30a for displaying images and receiving user input, a transceiver 30d housed in the housing 30a and serving as a communication unit capable of wireless communication with external devices, a memory 30e housed in the housing 30a as a storage unit, a processing unit 30f housed in the housing 30a for controlling the various components of the mobile terminal 30 by executing a program, a GPS (Global Positioning System) receiver 30g, and a bus 30h communicatively connecting these components, thereby enabling the mobile terminal 30 to obtain its own location information. The inertial measurement unit 30b may be a unit that detects only triaxial acceleration without detecting triaxial angular velocity. Moreover, the mobile terminal 30 may be provided with a receiver that receives signals that can be used for positioning, such as a Global Navigation Satellite System (GNSS), instead of the GPS receiver 30g.

[0032] The mobile terminal 30 and the damping force control device 1 can exchange information with each other via the transceiver 30d and the communication unit 5. When an application program for setting parameters of the damping force control device 1 is started by an operator, the mobile terminal 30 becomes capable of communicating with the damping force control device 1 and can set parameters in the damping force control device 1.

[0033] The control unit 3 includes an acceleration calculation unit 3a that calculates the vertical acceleration directly above the four wheels W of the vehicle body B from the three angular velocities and three accelerations of the vehicle body B detected by the sensor unit 2, and a target damping force calculation unit 3b that calculates the target damping force from the vertical accelerations of the four locations of the vehicle body B calculated by the acceleration calculation unit 3a.

[0034] The acceleration calculation unit 3a calculates the vertical acceleration directly above the four wheels W of the vehicle body B from the three angular velocities and three accelerations at the installation position of the vehicle body B detected by the sensor unit 2. Since the detection axes for detecting the three-axial acceleration of the sensor unit 2 may not be perfectly aligned with the front-rear, left-right, and up-down directions of the vehicle body B and the sensor unit 2 may not be installed on the vehicle body B so as to coincide with the center of gravity of the vehicle body B, the acceleration calculation unit 3a corrects the three angular velocities and accelerations detected by the sensor unit 2 to calculate the vertical acceleration directly above the four wheels W of the vehicle body B, and calculates the three angular velocities and accelerations at the center of gravity position of the vehicle body B.

[0035] In addition, the acceleration calculation unit 3a corrects the three angular velocities and accelerations detected by the sensor unit 2 to obtain three angular velocities and accelerations at the center of gravity of the vehicle body B, and then obtains the vertical accelerations directly above the four wheels W of the vehicle body B from these obtained angular velocities and accelerations.

[0036] Specifically, the acceleration calculation unit 3a calculates the vertical acceleration directly above the four wheels W of vehicle body B from information on the tread and wheelbase of vehicle V and the center of gravity position of vehicle body B. If the positions directly above the four wheels W of vehicle body B and the center of gravity position are known, the vertical acceleration directly above the four wheels W of vehicle body B can be calculated from the three angular velocities and acceleration at the center of gravity position of vehicle body B. If the center of gravity position of vehicle body B and the tread and wheelbase of vehicle V are known, the relationship between the center of gravity position of vehicle body B and the positions directly above the four wheels W of vehicle body B can be determined, so the acceleration calculation unit 3a can calculate the vertical acceleration directly above the four wheels W of vehicle body B from the tread and wheelbase of vehicle V, information on the center of gravity position of vehicle body B, and the three angular velocities and acceleration at the center of gravity position of vehicle body B.

[0037] The tread and wheelbase of vehicle V and the position of the center of gravity of vehicle body B can be obtained from the specification information of vehicle V, and the tread and wheelbase of vehicle V on which the damping force control device 1 is mounted and the position of the center of gravity of vehicle body B can be input from a mobile terminal 30 described later. Since it may be difficult for a user who is not familiar with vehicle V to access the specification information of vehicle V, it may be possible to enable the mobile terminal 30 to obtain information on the tread, wheelbase and position of the center of gravity of vehicle body B by selecting the manufacturer and model of vehicle V in an application program for setting parameters of the damping force control device 1 executed by the mobile terminal 30 described later, and then send that information to the damping force control device 1. Furthermore, if the damping force control device 1 has specification information corresponding to the vehicle model and body type stored in advance in a memory (described later) in the hardware constituting the control unit 3, the application program may be executed to receive input of information about the vehicle model and body type of the vehicle V from the mobile terminal 30, the damping force control device 1 may select a tread, wheelbase, and center of gravity position that are compatible with the input manufacturer and vehicle model, and the acceleration calculation unit 3a may use the selected tread, wheelbase, and center of gravity position to calculate the vertical accelerations directly above the four wheels W of the vehicle body B. Furthermore, although this will be somewhat inaccurate, the acceleration calculation unit 3a may also calculate three angular velocities and accelerations at the center of gravity position of the vehicle body B using information about the tread, wheelbase, and center of gravity position of the vehicle body B, and then calculate the vertical accelerations directly above the four wheels W of the vehicle body B from the calculated angular velocities and accelerations.

[0038] In this embodiment, in order to perform skyhook control, the target damping force calculation unit 3b integrates or filters the vertical acceleration of the vehicle body B directly above the four wheels W calculated by the acceleration calculation unit 3a to calculate the vertical velocity of the vehicle body B directly above the four wheels W, and multiplies each of the vertical velocities of the vehicle body B directly above the four wheels W by a skyhook damping coefficient to calculate the skyhook damping force that should be generated by each of the four shock absorbers D interposed between each wheel W and the vehicle body B.

[0039] In addition, the target damping force calculation unit 3b multiplies the angular velocity in the roll direction of the vehicle body B at the center of gravity position of the vehicle body B by the roll suppression gain to obtain a roll suppression force that suppresses the roll, and multiplies the angular velocity in the pitch direction by the pitch suppression gain to obtain a pitch suppression force that suppresses the pitch.

[0040] Furthermore, the target damping force calculation unit 3b adds the roll suppression force and pitch suppression force that should be output by each of the four shock absorbers D to the skyhook damping force of each wheel W of the vehicle body B to calculate a damping force for ride comfort based on ride comfort control aimed at improving ride comfort in the vehicle V.

[0041] In addition, the target damping force calculation unit 3b multiplies the longitudinal acceleration of the center of gravity position of the vehicle body B by the longitudinal acceleration gain to obtain a longitudinal attitude change suppression force aimed at suppressing nose dive and squat of the vehicle body B during sudden acceleration or sudden braking, and multiplies the lateral acceleration of the center of gravity position of the vehicle body B by the lateral acceleration gain to obtain a lateral attitude change suppression force aimed at suppressing roll of the vehicle body B during cornering, and adds the longitudinal attitude change suppression force and lateral attitude change suppression force to be output by each of the four shock absorbers D to obtain a damping force for driving performance based on driving performance improvement control aimed at stabilizing the attitude of the vehicle body B of the vehicle V.

[0042] Then, the target damping force calculation unit 3b performs a high select process to select the larger absolute value of the ride comfort damping force value and the driving performance damping force value, and calculates the larger absolute value as the composite damping force. Note that, in calculating the composite damping force, the target damping force calculation unit 3b may add the ride comfort damping force and the driving performance damping force in a predetermined distribution. For example, the target damping force calculation unit 3b may calculate the composite damping force by adding together the value obtained by multiplying the ride comfort damping force by the ride comfort distribution gain and the value obtained by multiplying the driving performance damping force by the driving performance distribution gain, using a ride comfort control gain that determines the distribution of the ride comfort damping force based on the ride comfort control and a driving performance control gain that determines the distribution of the driving performance damping force based on the driving performance improvement control, each of which takes a value between 0 and 1.

[0043] Finally, the target damping force calculation unit 3b multiplies the composite damping force by a speed gain proportional to the traveling speed of the vehicle V to calculate the target damping force to be generated by the four shock absorbers D. The speed gain is calculated by multiplying the speed of the vehicle V by a speed sensitivity coefficient, and the speed gain increases in proportion to the traveling speed. The damping force control device 1 obtains the speed of the vehicle V from the mobile terminal 30. As described above, the mobile terminal 30 is equipped with a GPS receiver 30g, which detects the mobile terminal 30's own position information at a predetermined sampling period. The calculation processing unit 30f calculates the travel distance from the current position information and the position information obtained at the previous sampling period, and divides the calculated travel distance by the sampling period to calculate the traveling speed of the mobile terminal 30. The mobile terminal 30 performs wireless communication according to the above-mentioned standard, and therefore can only communicate with the damping force control device 1 over short distances. Therefore, when the mobile terminal 30 is traveling together with the vehicle V, it can transmit the speed information of the vehicle V to the damping force control device 1 via wireless communication. In this way, when the mobile terminal 30 and the damping force control device 1 are able to communicate wirelessly, the mobile terminal 30 continuously transmits speed information of the vehicle V to the damping force control device 1, and when the damping force control device 1 receives input of the speed of the vehicle V from the mobile terminal 30, it multiplies the speed by a speed sensitivity coefficient to determine a speed gain, and multiplies the speed gain by the composite damping force to determine a target damping force. Thus, the damping force control device 1 of this embodiment can obtain speed information of the vehicle V and determine a target damping force appropriate for the speed, even without being connected to the CAN bus of the vehicle V.

[0044] Instead of multiplying the composite damping force by the speed gain, the composite damping force may be calculated by individually multiplying either the ride comfort damping force or the driving performance damping force by the speed gain and then performing high select processing or by using the distribution described above. Note that, since the speed change of the vehicle V is sufficiently slower than the change in acceleration, etc. detected by the sensor unit 2, even if the damping force control device 1 obtains speed information of the vehicle V from the mobile terminal 30 and uses this information to control the target damping force, it does not adversely affect the control of the damping force. On the other hand, the damping force control device 1 is equipped with the sensor unit 2 and can obtain the acceleration and angular velocity of the vehicle body B at a short sampling period to control the shock absorber D with good responsiveness. Note that the damping force control device 1 may also obtain only position information from the mobile terminal 30 at a fixed period, calculate the speed of the vehicle V, and use the obtained speed to calculate the speed gain.

[0045] As described above, the target damping force calculation unit 3b in the control unit 3 acquires position information from the mobile terminal 30 and calculates the speed of the vehicle V, but if position information cannot be obtained from the mobile terminal 30, the target damping force may be calculated by calculating the speed from the acceleration detected by the sensor unit 2 and treating this as the speed of the vehicle V. Furthermore, if position information can be acquired from the mobile terminal 30 but the position information from the mobile terminal 30 is interrupted, such as when the vehicle V is traveling through a tunnel and the GPS receiver 30g cannot receive signals from a satellite, the target damping force calculation unit 3b in the control unit 3 may calculate the speed from the acceleration detected by the sensor unit 2 and treating this as the speed of the vehicle V to calculate the target damping force.

[0046] The target damping forces of the four shock absorbers D thus obtained are input to a current control unit 16 that controls the current supplied from the control unit 3 to the damping force adjustment unit 15 of each shock absorber D. The current control unit 16 supplies current to the solenoid 15c in the damping force adjustment unit 15 of each shock absorber D so that the damping force generated by the shock absorber D matches the target damping force.

[0047] 4, in this embodiment, the current control unit 16 is configured to include a control calculation unit 16a that generates a current command for controlling the damping force adjusting unit 15, and a drive circuit 16b that supplies current to the solenoid 15c in accordance with the current command generated by the control calculation unit 16a. Four drive circuits 16b are provided corresponding to the damping force adjusting units 15 of the four shock absorbers D. The current control unit 16 receives power supply through a power supply line connected to a battery (not shown) of the vehicle V.

[0048] Control calculation unit 16a calculates a target current based on a control command indicating a target damping force obtained from control unit 3. Specifically, control calculation unit 16a includes a current command calculation unit 16a1 that generates a current command indicating the amount of current to be applied to solenoid 15c of damping force adjustment unit 15 based on the target damping force indicated by the control command, and a PWM signal generation unit 16a2 that outputs a PWM signal to drive circuit 16b upon receiving the current command from current command calculation unit 16a1.

[0049] The current command calculation unit 16a1 stores in advance a map that indicates the relationship between the damping force generated by the shock absorber D and the amount of current supplied to the solenoid 15c of the damping force adjustment unit 15, and calculates the amount of current to be supplied to the solenoid 15c of the damping force adjustment unit 15 by map calculation from the target damping force input from the control unit 3. Note that the current command calculation unit 16a1 calculates the amount of current using the map, but if the relationship between the target damping force and the amount of current can be expressed as a function, the current amount may also be calculated using the function. In this way, the current command calculation unit 16a1 generates a current command that indicates the calculated amount of current.

[0050] The PWM signal generating unit 16a2 calculates the deviation between the current command calculated by the current command calculating unit 16a1 and the actual amount of current supplied to the solenoid 15c, performs PI compensation or PID compensation on the deviation to calculate a target current, and outputs a PWM signal for causing the drive circuit 16b to supply current to the solenoid 15c of the damping force adjusting unit 15 in accordance with the target current. In other words, the PWM signal generating unit 16a2 controls the damping force adjusting unit 15 by current feedback control. The PWM signal generating unit 16a2 obtains information on the current flowing through the solenoid 15c from a current sensor provided in the drive circuit 16b. The drive circuit 16b is connected to the solenoid 15c in the damping force adjustment unit 15 via wiring 17, and in order to adjust the amount of current supplied to the solenoid 15c, it is equipped with a switching element (not shown in detail) that can connect and disconnect the solenoid 15c to a power source not shown, and turns the switching element on and off at a duty ratio indicated by the PWM signal received from the PWM signal generation unit 16a2, thereby adjusting the amount of current to the solenoid 15c according to the target current.

[0051] The configuration of the current control unit 16 is just one example, and the current control unit 16 may supply current to the damping force adjustment unit 15 so as to generate a damping force in the shock absorber D in accordance with the target damping force indicated by the control command output by the control unit 3.

[0052] As described above, the target damping force calculation unit 3b in the control unit 3 uses various parameters, such as the skyhook damping coefficient, roll suppression gain, pitch suppression gain, longitudinal acceleration gain, lateral acceleration gain, and speed sensitivity coefficient, to determine the target damping force. As such, the parameters are set in advance and used for control, and are used to calculate the target damping force. In this embodiment, the damping force control device 1 executes ride comfort control aimed at improving ride comfort and driving performance improvement control aimed at improving driving performance, and the parameters used for these controls can be set using the mobile terminal 30.

[0053] Furthermore, when the damping force control device 1 does not perform the above control and causes the shock absorber D to function as a passive damper that generates a predetermined damping force in response to the extension / contraction speed, the damping force control device 1 allows the damping coefficient of the shock absorber D to be set as a parameter using the mobile terminal 30. When the damping force control device 1 causes the shock absorber D to function as a passive damper, the control unit 3 provides a fixed current command corresponding to the damping coefficient to the current control unit 16 so that the shock absorber D generates a damping force with the predetermined damping coefficient.

[0054] Although not shown as hardware, the control unit 3 and the control calculation unit 16a in the current control unit 16 include a CPU (Central Processing Unit), a memory, an interface, and a bus that connects these devices so that they can communicate with each other. Therefore, the damping force control device 1 is capable of two-way communication with a mobile terminal 30 outside the damping force control device 1 via the communication unit 5, and is also capable of supplying current from the drive circuit 16b to the damping force adjustment unit 15.

[0055] The CPU executes the operating system and other programs to realize the arithmetic processing of each part in the acceleration calculation part 3a and the target damping force calculation part 3b in the control part 3 of the damping force control device 1, as well as the arithmetic processing of the control calculation part 16a of the current control part 16, and controls the communication part 5. In addition to ROM (Read Only Memory), the memory includes RAM (Random Access Memory) and flash memory that provide storage areas necessary for the arithmetic processing of the CPU, and the programs used for the arithmetic processing of the CPU are stored in the ROM. Note that the programs used for the arithmetic processing of the CPU may be stored in a storage device other than the memory.

[0056] The damping force control device 1 configured as described above operates by receiving power supply from a battery (not shown) in the vehicle V, is started when the ignition switch is turned on, and starts processing to control the damping force of the shock absorber D. Below, the processing of the damping force control device 1 that controls the damping force of the shock absorber D and the processing of the mobile terminal 30 will be described.

[0057] 6, the control unit 3 in the damping force control device 1 corrects the three-axial angular velocities and three-axial accelerations input from the sensor unit 2 at a predetermined sampling period to determine the three-axial angular velocities and three-axial accelerations at the center of gravity of the vehicle body B (step S101). Next, the control unit 3 determines the vertical accelerations and vertical velocities directly above the four wheels W of the vehicle body B from the three-axial angular velocities and three-axial accelerations at the center of gravity of the vehicle body B (step S102).

[0058] Furthermore, in this embodiment, in order to perform skyhook control, the control unit 3 multiplies the vertical velocity of the vehicle body B directly above the four wheels W by a skyhook damping coefficient to obtain a skyhook damping force (step S103). The control unit 3 also multiplies the angular velocity in the roll direction of the vehicle body B at the center of gravity position of the vehicle body B by a roll suppression gain to obtain a roll suppression force that suppresses roll, and multiplies the angular velocity in the pitch direction by a pitch suppression gain to obtain a pitch suppression force that suppresses pitch (step S104).

[0059] Next, the control unit 3 calculates a damping force for ride comfort by adding the roll restraint force and pitch restraint force to be output by each of the four shock absorbers D to the skyhook damping force of each wheel W of the vehicle body B (step S105). Furthermore, the control unit 3 calculates a longitudinal attitude change restraint force by multiplying the longitudinal acceleration of the center of gravity of the vehicle body B by a longitudinal acceleration gain, and calculates a lateral attitude change restraint force by multiplying the lateral acceleration of the center of gravity of the vehicle body B by a lateral acceleration gain (step S106), and calculates a damping force for driving performance by adding the longitudinal attitude change restraint force and the lateral attitude change restraint force together (step S107).

[0060] Then, the control unit 3 performs a high select process to adopt the larger absolute value of the damping force for ride comfort and the damping force for driving performance to obtain a composite damping force (step S108). Furthermore, the control unit 3 multiplies the speed of the vehicle V by a speed sensitivity coefficient to obtain a speed gain, and multiplies the composite damping force by the speed gain to obtain target damping forces to be generated by the four shock absorbers D (step S109).

[0061] After determining the target damping force in this manner, the control unit 3 outputs a current command indicating the target damping force to the current control unit 16 (step S114). The damping force control device 1 repeatedly executes the processes from step S101 to step S110 to control the damping force of the shock absorber D.

[0062] Furthermore, in the calculation process of the target damping force, the damping force control device 1 uses the speed of the vehicle V, and therefore executes a process to determine the speed of the vehicle V from the position input from the mobile terminal 30, separate from the process of executing damping force control. When the damping force control device 1 is started up and is able to establish communication with the mobile terminal 30, it requests the mobile terminal 30 to transmit the position of the vehicle V, and once the mobile terminal 30 receives a GPS signal with the GPS receiver 30g and determines the position, it inputs the determined position to the damping force control device 1. The position output by the mobile terminal 30 is input to the damping force control device 1 as coordinates.

[0063] Specifically, as shown in Fig. 7, the damping force control device 1 waits for a position input from the mobile terminal 30 and determines whether or not a position input has been received (step S201). If a position input has not been received, the damping force control device 1 determines whether or not a predetermined waiting time has elapsed since waiting for the input of position information (step S202). If the time that has elapsed since waiting for the position input is less than the predetermined waiting time, the process returns to step S201 and determines whether or not a position input has been received.

[0064] When a position is input, the damping force control device 1 calculates the speed of the vehicle V based on the input position, the most recent position input at a time before the time the position input was received, and the difference in the time at which the two positions were input (step S203). Specifically, the damping force control device 1 calculates the travel distance of the vehicle V from the coordinates of the two positions, calculates the travel time from the difference between the two times, and calculates the speed of the vehicle V by dividing the travel distance by the travel time.

[0065] If it is determined in step S202 that a predetermined waiting time has elapsed since waiting for the position input, the position cannot be obtained from the mobile terminal 30, so the damping force control device 1 calculates the speed by integrating the longitudinal acceleration at a predetermined position of the vehicle body B obtained by correcting the acceleration detected by the sensor unit 2, and sets the calculated speed as the speed of the vehicle V (step S204).

[0066] When the damping force control device 1 is started by turning on the ignition switch, it separately performs a process of continuously integrating the acceleration in the longitudinal direction at a predetermined position of the vehicle body B to obtain the speed.

[0067] Therefore, if the vehicle V enters a tunnel or the like while traveling and the mobile terminal 30 is unable to receive GPS signals and therefore unable to input the position of the vehicle V into the damping force control device 1, or if there is a problem with the mobile terminal 30 and the position cannot be input, the damping force control device 1 uses the acceleration detected by the sensor unit 2 to determine the speed of the vehicle V. The damping force control device 1 repeatedly executes the process of determining the speed to continuously determine the speed and use it for controlling the damping force. Since determining the speed from the position detected by the mobile terminal 30 can determine the speed more accurately than determining the speed by integrating the acceleration, when the position can be obtained from the mobile terminal 30, the damping force control device 1 determines the speed of the vehicle V using the position obtained from the mobile terminal 30.

[0068] If the position cannot be obtained from the mobile terminal 30, the latest speed that can be calculated from the input position may be used as the speed of the vehicle V. Alternatively, the mobile terminal 30 may detect the position from a GPS signal received by the GPS receiver 30g, and further calculate the speed of the vehicle V from the detected position and input the speed instead of the position to the damping force control device 1. In this case, the damping force control device 1 may control the damping force of the shock absorber D using the speed obtained from the mobile terminal 30 without performing the processing of step S203.

[0069] In this way, when the damping force control device 1 can obtain the position from the mobile terminal 30, it calculates the speed of the vehicle V based on the received position, and when the damping force control device 1 cannot obtain the position from the mobile terminal 30, it calculates the speed of the vehicle V using the acceleration detected by its own sensor unit 2, so that when controlling the damping force, the shock absorber D can seamlessly exert a damping force that is sensitive to the speed.

[0070] As described above, the damping force control system S of this embodiment comprises a sensor unit 2 that detects vibrations of the body B of the vehicle V, a control unit 3 that controls the damping force of a damping force adjustable shock absorber D provided between the body B and the wheels W of the vehicle V based on vibration information detected by the sensor unit 2, a damping force control device 1 having a communication unit 5 capable of wireless communication, and a mobile terminal 30 that can communicate with the damping force control device 1, and the control unit 3 controls the shock absorber D based on the speed determined from the position detected by the mobile terminal 30 or the speed detected by the mobile terminal 30.

[0071] According to the damping force control system S configured in this manner, the damping force control device 1 can obtain the position or speed of the vehicle V from the mobile terminal 30, and can control the damping force of the shock absorber D in response to the speed of the vehicle V without being connected to the CAN bus in the vehicle V. Therefore, even when the damping force control device 1 is retrofitted to the vehicle V, the damping force control device 1 can be easily installed on the vehicle V, and the installation work is also simple.

[0072] In addition, the sensor unit 2 in the damping force control system S of this embodiment is capable of detecting the longitudinal acceleration of the vehicle body B, and when the position or velocity cannot be obtained from the mobile terminal 30, the control unit 3 determines the velocity of the vehicle V from the longitudinal acceleration of the vehicle body B detected by the sensor unit 2, and controls the shock absorber D based on the determined velocity.

[0073] According to the damping force control system S configured in this manner, even if the position or speed cannot be obtained from the mobile terminal 30, the speed of the vehicle V can be seamlessly obtained and control of the damping force of the shock absorber D to be sensitive to the speed can be continued.

[0074] In addition, the damping force control device 1 of this embodiment is equipped with a sensor unit 2 that detects vibration information of the vehicle body B, and therefore, compared to obtaining vibration information of the vehicle body B from a mobile terminal 30, the vibration information necessary for controlling the damping force can be obtained at the high sampling rate required for controlling the damping force, and the damping force of the shock absorber D can be controlled with good responsiveness.

[0075] Furthermore, the damping force control device 1 of this embodiment includes a housing 20 that houses the sensor unit 2, the control unit 3, and the communication unit 5. According to the damping force control device 1 configured in this manner, simply installing the housing 20 on the vehicle body B also completes the installation of the sensor unit 2 that detects vibration information of the vehicle body B, making installation on the vehicle V easy. Furthermore, according to the damping force control device 1 of this embodiment, since the sensor unit 2 is housed in the housing 20, installing the housing 20 near the center of gravity of the vehicle body B makes it possible to detect vibration information of the vehicle body B with high accuracy and achieve good controllability when controlling the damping force of the shock absorber D.

[0076] In the damping force control device 1 of this embodiment, the sensor unit 2, the control unit 3, the communication unit 5, and the current control unit 16 are housed in a single housing 20. With the damping force control device 1 configured in this manner, if the power supply is connected only to the housing 20, wiring for supplying power from the vehicle V to each shock absorber D is not required, making it easy to install the damping force control device 1 on the vehicle V. However, the current control unit 16 may be installed on the shock absorber D side, or the drive circuit 16b of the current control unit 16 may be installed on the shock absorber D side. Furthermore, if an acceleration sensor that detects the acceleration of the wheel W is provided on the shock absorber D so that vibration information of the wheel W can be obtained, the damping force control device 1 may perform fine-tuned control of the damping force using the vibration information of the wheel W.

[0077] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0078] 1···Damping force control device, 2···Sensor unit, 3···Control unit, 5···Communication unit, 30···Mobile terminal, B···Vehicle body, D···Shock absorber, S···Damping force control system, V···Vehicle, W···Wheel

Claims

1. a damping force control device including a sensor unit that detects vibrations of a vehicle body, a control unit that controls the damping force of an adjustable damping force shock absorber that is provided between the vehicle body and a wheel of the vehicle based on vibration information detected by the sensor unit, and a communication unit that is capable of wireless communication; a mobile terminal capable of communicating with the damping force control device, The control unit controls the shock absorber based on a speed determined from a position detected by the mobile terminal or a speed detected by the mobile terminal. A damping force control system characterized by:

2. The sensor unit is capable of detecting acceleration in a front-rear direction of the vehicle body, When the position or the speed cannot be obtained from the mobile terminal, the control unit calculates the speed of the vehicle from the acceleration in the front-rear direction of the vehicle body detected by the sensor unit, and controls the shock absorber based on the calculated speed.

2. The damping force control system according to claim 1.

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