Electric suspension system

Abstract

To provide a power suspension device capable of improving the measurement accuracy of a position of an electric actuator while simplifying or omitting a system configuration.SOLUTION: A power suspension device mounted in a vehicle includes: an electric actuator that performs a stroke operation according to a behavior of the vehicle; a motor that drives the electric actuator; a rotation angle sensor that detects a rotation angle of the motor; and a control device that controls the electric actuator. The control device calculates a stroke amount of the electric actuator on the basis of a rotation angle change amount of the rotation angle sensor and controls the electric actuator on the basis of the calculated stroke amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric suspension system and a method for controlling an electric suspension. [Background technology]

[0002] In recent years, there has been a surge in efforts to provide access to sustainable transportation systems that take into account vulnerable groups such as the elderly, people with disabilities, and children. To achieve this, we are focusing on research and development to further improve the safety and convenience of transportation through the development of vehicle behavior stability.

[0003] From the perspective of vehicle behavioral stability, it is desirable to improve the operational accuracy of the suspension system mounted on the vehicle. Patent Document 1 discloses a suspension control technology that detects the position (stroke position, relative position, absolute position) of actuators provided corresponding to each wheel of the vehicle and determines abnormalities in the reverse swing of the actuators based on changes in their positions. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6480202 [Overview of the project] [Problems that the invention aims to solve]

[0005] To improve vehicle stability, it is necessary to simplify the system configuration while improving measurement accuracy when detecting the position of the electric suspension actuator.

[0006] An object of the present invention is to provide an electric suspension device and a control method for an electric suspension that can improve the measurement accuracy of the position of an electric actuator while simplifying or omitting the system configuration. And it contributes to the development of a sustainable transportation system.

Means for Solving the Problems

[0007] (1) The electric suspension device according to the present invention is an electric suspension device (for example, the electric suspension device 10 described later) mounted on a vehicle (for example, the vehicle 1 described later), and an electric actuator (for example, the electric actuator 12 described later) that performs a stroke operation according to the behavior of the vehicle, a motor (for example, the motor 13 described later) that drives the electric actuator, a rotation angle sensor (for example, the resolver S1 described later) that detects the rotation angle of the motor, and a control device (for example, the control device 20 described later) that controls the electric actuator. The control device calculates the stroke amount of the electric actuator based on the amount of change in the rotation angle of the rotation angle sensor, and controls the electric actuator based on the calculated stroke amount.

[0008] (2) In the electric suspension device according to (1) above, the control device may set the stroke amount of the electric actuator at the start of the electric suspension device to a fixed initial value.

[0009] (3) In the electric suspension device according to (1) above, the control device may set the stroke amount of the electric actuator at the start of the electric suspension device to the value at the end of the previous time of the electric suspension device.

[0010] (4) In the electric suspension device according to any one of (1) to (3) above, a vibration detection sensor for detecting vibration of the vehicle (for example, resolver S1, spring upper G sensor S2, vehicle body roll rate sensor S3, vehicle body pitch rate sensor S4, and vehicle speed sensor S5 described later) is further provided, and when the control device determines that there is no vibration of the vehicle based on the detection result of the vibration detection sensor, the stroke amount of the electric actuator may be set to a fixed value.

[0011] (5) In the electric suspension device according to (4) above, when the control device determines that there is no vibration of the vehicle over a predetermined number of times or a predetermined time based on the detection result of the vibration detection sensor, the stroke amount of the electric actuator may be set to a fixed value.

[0012] (6) In the electric suspension device according to any one of (1) to (5) above, when the calculated stroke amount exceeds a predetermined upper limit value (for example, upper limit threshold value X Hi ) or falls below a predetermined lower limit value (for example, lower limit threshold value X Lo ), the control of the electric actuator may be stopped.

[0013] (7) In the electric suspension device according to (6) above, the electric actuator is provided for each of a plurality of wheels of the vehicle, and when the stroke amount of the electric actuator corresponding to one of the wheels among the plurality of electric actuators exceeds the predetermined upper limit value or falls below the predetermined lower limit value, the control of the electric actuator corresponding to the wheel adjacent to the wheel or all the wheels may be stopped.

[0014] (8) In the electric suspension device according to (6) or (7) above, when the stroke amount of the electric actuator exceeds the predetermined upper limit value or falls below the predetermined lower limit value, the control device may output a signal for limiting the vehicle speed.

[0015] (9) The electric suspension control method according to the present invention is a control method for an electric suspension comprising an electric actuator (e.g., electric actuator 12 described later) mounted on a vehicle (e.g., vehicle 1 described later) and performing stroke operation according to the behavior of the vehicle, wherein the stroke amount of the electric actuator is calculated based on the amount of change in the rotation angle of a rotation angle sensor (e.g., resolver S1 described later) that detects the rotation angle of a motor (e.g., motor 13 described later) that drives the electric actuator, and the electric actuator is controlled based on the calculated stroke amount. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an electric suspension device and an electric suspension control method that can improve the measurement accuracy of the position of an electric actuator while simplifying or omitting the system configuration. [Brief explanation of the drawing]

[0017] [Figure 1] This is a diagram showing the configuration of a vehicle equipped with an electric suspension system according to an embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of an electric suspension device according to an embodiment of the present invention. [Figure 3] This figure shows an example of the configuration of an inverter for an electric suspension device according to an embodiment of the present invention. [Figure 4] This flowchart shows an example of control of an electric suspension in an electric suspension device according to an embodiment of the present invention. [Figure 5] This flowchart shows an example of the midpoint learning process for an electric suspension in an electric suspension device according to an embodiment of the present invention. [Figure 6] This flowchart shows an example of the abnormality detection process for the electric suspension in an electric suspension device according to an embodiment of the present invention. [Figure 7] This figure illustrates the amount of change in the resolver electrical angle in an electric suspension device according to an embodiment of the present invention. [Figure 8] This flowchart shows another example of the process for calculating the stroke amount of the electric suspension in an electric suspension device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will now be described in detail with reference to the drawings. Figure 1 is a diagram showing the configuration of a vehicle 1 equipped with an electric suspension device 10 according to an embodiment of the present invention. Figure 2 is a diagram showing the configuration of the electric suspension device 10. In this embodiment, the vehicle 1 is shown as a gasoline vehicle, but it may also be a diesel vehicle or an electric vehicle (including hybrid vehicles and fuel cell vehicles).

[0019] As shown in Figure 1, the vehicle 1 comprises a body BD, four wheels TR, and an electric suspension system 10. The electric suspension system 10 includes an electric actuator 12, a motor 13, and a control device 20. These electric actuators 12, motor 13, and control device 20 constitute the electric suspension.

[0020] The electric actuator 12 consists of a first electric actuator 12A, a second electric actuator 12B, a third electric actuator 12C, and a fourth electric actuator 12D, corresponding to the four wheels TR. The first electric actuator 12A is positioned between the vehicle body BD and the right front wheel. The second electric actuator 12B is positioned between the vehicle body BD and the left front wheel. The third electric actuator 12C is positioned between the vehicle body BD and the right rear wheel. The fourth electric actuator 12D is positioned between the vehicle body BD and the left rear wheel.

[0021] Each of the first electric actuators 12A to the fourth electric actuator 12D has substantially the same configuration. Therefore, in the following, when the first electric actuator 12A to the fourth electric actuator 12D are not distinguished from each other, they may simply be referred to as electric actuator 12.

[0022] Next, the configuration of the electric actuator 12 will be described with reference to Figure 2. As shown in Figure 2, the electric actuator 12 includes a connecting portion 121, an inner cylinder 122, and a ball screw nut 123 as components on the wheel TR side. The electric actuator 12 also includes an outer cylinder 124, a ball screw shaft 125, and a bearing 126 as components on the vehicle body BD side. The motor 13 is positioned on the vehicle body BD side, similar to the components on the vehicle body BD side of the electric actuator 12. The outer cylinder 124 and the bearing 126 are fixed to the chassis 11 located at the bottom of the vehicle body BD.

[0023] The ball screw shaft 125 is supported by a bearing 126 and a ball screw nut 123. The inner surface of the ball screw nut 123 is screwed into a thread groove formed on the outer surface of the ball screw shaft 125 via the bearing. The ball screw shaft 125 is coaxially connected to the rotating shaft of the motor 13. The motor 13 rotates the ball screw shaft 125, thereby moving the ball screw nut 123 vertically. As the ball screw nut 123 moves downward, the inner cylinder 122 moves downward. As the ball screw nut 123 moves upward, the inner cylinder 122 moves upward. In this way, the vertical stroke amount (stroke position) of the inner cylinder 122 relative to the outer cylinder 124 fixed to the chassis 11 of the vehicle body BD is adjusted.

[0024] The connecting portion 121 is connected to the wheel TR by being fixed to the knuckle (not shown) of the suspension device. The electric actuator 12 performs a stroke operation in accordance with the behavior of the wheel TR when the vehicle 1 is running. That is, when vibration is input to the connecting portion 121 from the wheel TR side when the vehicle 1 is running, acceleration is applied to the connecting portion 121. When upward acceleration is applied to the connecting portion 121, the inner cylinder 122 and ball screw nut 123 rise. Also, when downward acceleration is applied to the connecting portion 121, the inner cylinder 122 and ball screw nut 123 descend. When the inner cylinder 122 and ball screw nut 123 of the electric actuator 12 rise or fall, the motor 13 rotates the ball screw shaft 125 in a direction that absorbs the upward acceleration (a direction that compresses the electric actuator 12) or in a direction that absorbs the downward acceleration (a direction that pulls the electric actuator 12). This reduces vibrations transmitted from the wheels TR to the vehicle body BD.

[0025] A resolver S1 is provided on the electric actuator 12. The resolver S1 is an example of a rotation angle sensor that detects the rotation angle (electrical angle) of the motor 13 of the electric actuator 12. Note that the detection of the rotation angle of the motor 13 of the electric actuator 12 is not limited to the resolver S1, and other rotation angle sensors such as a rotary encoder may be used. Such rotation angle sensors are generally installed in three-phase AC brushless motors.

[0026] As shown in Figures 1 and 2, the vehicle body BD is equipped with a sprung mass G sensor S2 for detecting the acceleration of the sprung mass of the vehicle body BD, a vehicle body roll rate sensor S3 for detecting the angular velocity of the vehicle body BD with the longitudinal direction as the axis of rotation, a vehicle body pitch rate sensor S4 for detecting the angular velocity of the vehicle body BD with the lateral direction as the axis of rotation, and a vehicle speed sensor S5 for detecting the vehicle speed. The sprung mass G sensor S2 consists of a first sprung mass G sensor S2A corresponding to the first electric actuator 12A, a second sprung mass G sensor S2B corresponding to the second electric actuator 12B, a third sprung mass G sensor S2C corresponding to the third electric actuator 12C, and a fourth sprung mass G sensor S2D corresponding to the fourth electric actuator 12D. The detected values ​​from the resolver S1, sprung mass G sensor S2, vehicle body roll rate sensor S3, vehicle body pitch rate sensor S4, and vehicle speed sensor S5 are input to the control device 20. Since the resolver S1, sprung mass G sensor S2, vehicle body roll rate sensor S3, vehicle body pitch rate sensor S4, and vehicle speed sensor S5 all function as vibration detection sensors for detecting vibrations of the vehicle 1, they correspond to vibration detection sensors for detecting vibrations of the vehicle 1 in this embodiment.

[0027] The control device 20 is composed of an ECU (Electronic Control Unit) and controls each of the motors 13 of the first electric actuator 12A to the fourth electric actuator 12D. The control device 20 is electrically connected to each of the motors 13 of the first electric actuator 12A to the fourth electric actuator 12D via wiring. Each of the motors 13 of the first electric actuator 12A to the fourth electric actuator 12D and the control device 20 are supplied with predetermined power from the battery 30. Based on the detection results of the resolver S1, sprung mass G sensor S2, vehicle body roll rate sensor S3, vehicle body pitch rate sensor S4, and vehicle speed sensor S5, the control device 20 controls each of the motors 13 of the first electric actuator 12A to the fourth electric actuator 12D via the inverter 15.

[0028] As shown in Figure 2, the control device 20 includes a memory 20A and a processor 20B, and controls the motor 13 of the electric actuator 12 via an inverter 31. The memory 20A is a storage device that non-volatilely stores programs and data executed by the processor 20B. The memory 20A is composed of a magnetic storage device, a semiconductor storage element such as flash ROM (Read Only Memory), or other types of non-volatile storage devices. The memory 20A may also include RAM (Random Access Memory) which constitutes the work area of ​​the processor 20B. The memory 20A stores data processed by the control device 20 and control programs executed by the processor 20B. The processor 20B may consist of a single processor, or the functions of the processor 20B may be composed of multiple processors. The processor 20B executes the control program to control each part of the electric suspension device 10. However, the control program may be stored on an external HDD (not shown) and read from there.

[0029] The control device 20 includes a stroke amount calculation unit 21, a midpoint learning unit 22, an abnormality determination unit 23, and an output control unit 24. Specifically, the processor 20B of the control device 20 executes a control program, thereby enabling the control device 20 to perform the functions of the stroke amount calculation unit 21, the midpoint learning unit 22, the abnormality determination unit 23, and the output control unit 24.

[0030] The stroke amount calculation unit 21 calculates the stroke amount of the electric actuator 12, which strokes according to the behavior of the vehicle 1, based on the detected value of the rotation angle (electric angle) of the motor 13 of the electric actuator 12 input from the resolver S1. This stroke amount is also the stroke position of the electric actuator 12. Since the rotation axis of the motor 13 is coaxially connected to the ball screw shaft 125, the stroke amount of the electric actuator 12 is also the amount of rotation of the ball screw shaft 125, which rotates in conjunction with the up and down movement of the inner cylinder 122 and the ball screw nut 123.

[0031] The midpoint learning unit 22 determines the stroke position of the electric actuator 12 when the vehicle speed is 0 km / h, that is, when the vehicle 1 is stationary. The midpoint is the stroke position when the stroke operation of the electric actuator 12 is stopped when the vehicle 1 is stationary. When the vehicle speed becomes 0 km / h, the control device 20 determines whether or not the vehicle 1 is vibrating based on the detection values ​​input from the resolver S1, the sprung mass G sensor S2, the vehicle body roll rate sensor S3, and the vehicle body pitch rate sensor S4, based on the detection value from the vehicle speed sensor S5. When the control device 20 detects that the vehicle 1 is stationary, it sets the stroke position of the electric actuator 12 at that time as the midpoint. When the stroke operation stops, the stroke position of the electric actuator 12 returns to near the midpoint and stops due to the action of the suspension spring. This midpoint may change depending on the number of occupants, the amount of cargo loaded, etc.

[0032] The abnormality determination unit 23 determines whether the stroke amount of the electric actuator 12 calculated by the stroke amount calculation unit 21 exceeds a predetermined upper limit (upper threshold) or falls below a predetermined lower limit (lower threshold), that is, whether the stroke amount is stroking in the tension direction above the predetermined upper limit (upper threshold) or stroking in the compression direction below the predetermined lower limit (lower threshold).

[0033] The output control unit 24 controls the output to the electric actuator 12 according to the determination result of the abnormality determination unit 23, and controls the operation of the vehicle 1, including the operation of the electric actuator 12. Specifically, if the abnormality determination unit 23 determines that the stroke amount of the electric actuator 12 exceeds a predetermined upper limit (upper threshold) or falls below a predetermined lower limit (lower threshold), the control device 20 has the output control unit 24 perform control to stop the operation of the electric actuator 12, and control to limit the vehicle speed, etc.

[0034] The control device 20 controls the inverter 15, the short-circuit circuit 16, and the boost circuit 17 via the drive circuit 14. When stopping the operation of the motor 13 of the electric actuator 12, the control device 20 stops the operation of the motor 13 of the electric actuator 12 by short-circuiting the three-phase wires of the motor 13 via the drive circuit 14 and the short-circuit circuit 16, thereby applying an electromagnetic brake.

[0035] As shown in Figures 2 and 3, the control device 20 controls the inverter 15 via the drive circuit 14. The control device 20 controls the rotation direction and rotation speed of the motor 13 via the inverter 15. The control device 20 can also stop the power supply to the motor 13 by, for example, fixing the inverter 15 to the off position. By providing relays on the power lines of the inverter 15 and the boost circuit 17, the control device 20 may also stop the power supply to the motor 13 by tripping the relays.

[0036] Figure 3 shows an example of the configuration of the inverter 15. A boost circuit 17 is placed between the battery 30 and the inverter 15. The boost circuit 17 increases the voltage supplied from the battery 30 and supplies power to the inverter 15.

[0037] As shown in Figure 3, the inverter 15 (part of the driving elements) includes MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) 15U1, MOSFET 15U2, MOSFET 15V1, MOSFET 15V2, MOSFET 15W1, and MOSFET 15W2. Each of these six MOSFETs is turned on or off based on instructions from the control device 20.

[0038] The motor 13 is, for example, a three-phase AC brushless motor and comprises three motor coils 13u, motor coil 13v, and motor coil 13w, as shown in Figure 3. The motor 13 rotates the ball screw shaft 125 shown in Figure 2 using power supplied from the battery 30 via the inverter 15.

[0039] When the drive circuit 14 receives an instruction from the output control unit 24 of the control device 20 to stop supplying power to the motor 13, it will, for example, turn off the three positive MOSFETs, namely MOSFET 15U1, MOSFET 15V1, and MOSFET 15W1. By turning off MOSFET 15U1, MOSFET 15V1, and MOSFET 15W1, the power lines 40u, 40v, and 40w are disconnected from the boost circuit 17. As a result, the application of voltage to the motor coils 13u, 13v, and 13w of the motor 13 is stopped.

[0040] Furthermore, the control device 20 short-circuits the motor 13 via the short-circuit circuit 16. The short-circuit circuit 16 includes a switch (not shown) that turns on and off according to instructions from the control device 20, and a resistor (not shown). The switch of the short-circuit circuit 16 short-circuits, for example, the power lines 40u and 40v corresponding to the motor coils 13u and 13v, respectively, according to instructions from the output control unit 24. In the above case, the resistor of the short-circuit circuit 16 adjusts the current flowing to the motor coils 127u and 13v when the switch short-circuits the power lines 40u and 40v. Similarly, by short-circuiting the power lines 40v and 40w, a three-phase short-circuit state can be achieved for the motor coils 13u, 13v, and 13w.

[0041] The following describes a method for controlling the electric suspension for abnormality detection using the electric suspension device 10 configured as described above. Figure 4 is a flowchart showing an example of electric suspension control in the electric suspension device 10 according to this embodiment. The following processes are performed on each motor 13 of the four first electric actuators 12A to the fourth electric actuators 12D of the electric suspension device 10, but for the sake of simplicity, the process will be described here as the process for the motor 13 of one electric actuator 12.

[0042] First, in step S101, the control device 20 determines whether the electric suspension system 10 is starting up after the ignition of the vehicle 1 is turned ON. If it is determined that the system is starting up (step S101: YES), the process moves to step S102, where the control device 20, in the stroke amount calculation unit 21, calculates the stroke amount (integrated stroke position X) of the electric actuator 12 at startup. N Set the integrated stroke position X to a fixed initial value. N Although it is set to =0, the fixed initial value may be any value other than 0. By setting the stroke amount at system startup to a fixed initial value in this way, the control device 20 does not carry over the previous final value when calculating the stroke amount in the stroke amount calculation unit 21, thus simplifying the calculation control.

[0043] Next, in step S103, the control device 20 obtains a detected value of the rotation angle (electrical angle) of the motor 13 from the resolver S1 located on the motor 13 of the electric actuator 12. The obtained detected value is the current value θ. N This is set in the control device 20.

[0044] Next, in step S104, the control device 20 executes a midpoint learning process in the midpoint learning unit 22. A flowchart of this midpoint learning process is shown in Figure 5.

[0045] In the midpoint learning process, the control device 20 first determines in step S201 whether the vehicle speed is 0 km / h, that is, whether vehicle 1 is stopped, based on the detected value input from the vehicle speed sensor S5. If it is determined that vehicle 1 is stopped (step S201: YES), the process proceeds to step S202.

[0046] In step S202, the control device 20 determines whether there is vibration input to the vehicle 1 based on whether the detected value input from the sprung mass G sensor S2 is near zero. If it is determined that there is no vibration input to the vehicle 1 because the detected value is near zero (step S202: YES), the process proceeds to step S203.

[0047] In step S203, the control device 20 further determines whether there is vibration input to the vehicle 1 based on whether the detected value input from the vehicle body roll rate sensor S3 is near zero. If it is determined that there is no vibration input to the vehicle 1 because the detected value is near zero (step S203: YES), the process proceeds to step S204.

[0048] In step S204, the control device 20 further determines whether there is vibration input to the vehicle 1 based on whether the detected value input from the vehicle body pitch rate sensor S4 is near zero. If it is determined that there is no vibration input to the vehicle 1 because the detected value is near zero (step S204: YES), the process proceeds to step S205.

[0049] In step S205, the control device 20 further determines whether there is vibration input to the vehicle 1 by detecting whether the difference Δθ of the rotation angle (electrical angle) input from the resolver S1 is near zero, that is, whether the motor 13 is not rotating in either the forward or reverse direction. If it is determined that there is no vibration input to the vehicle 1 because the difference Δθ is near zero (step S205: YES), the process proceeds to step S206.

[0050] In step S206, the control device 20 determines that there is no vibration in the vehicle 1 and performs a midpoint learning process to determine the stroke amount (integrated stroke position X) of the electric actuator 12 at startup. N Set the midpoint to X ) in step S102 shown in Figure 4. N=0 is set as the midpoint. When the system is started, i.e., when the ignition is turned ON, various numbers of occupants and load amounts are expected for vehicle 1, so the control device 20 can calculate the precise stroke amount of the electric actuator 12 in response to these changes in the number of occupants and load amount.

[0051] If it is determined in step S201 that vehicle 1 is not stopped, and if it is determined in steps S202, S203, S204, and S205 that there is vibration input to the vehicle (steps S202-S205: NO), the process proceeds to step S207. In step S207, the control device 20 terminates the midpoint learning process in the midpoint learning unit 22 and proceeds to the next abnormality determination step.

[0052] The threshold values ​​used to determine whether the detected values ​​of each of the above sensors S2 to S4 are near zero are generally set to a range in which the electric actuator 12 can be considered not to be operating. Values ​​at the level of sensor noise can be considered near zero. The presence or absence of vibration input to the vehicle 1 may also be determined from the detected value of at least one of the above sensors S1 to S5. The presence or absence of vibration input to the vehicle 1 does not need to be determined from all of the detected values ​​of the above sensors S1 to S5, and can be set appropriately depending on the type of sensor mounted on the vehicle 1.

[0053] When there is no vibration input to the vehicle 1 (steps S201 to S205: YES), instead of executing the midpoint learning process once, the process of steps S201 to S205 is repeated while the timer in the control device 20 counts the determination time during which midpoint learning is possible. When it is determined that there is no vibration input to the vehicle 1 even if the count value continues for a preset predetermined time, the midpoint learning process may be executed, and the midpoint may be set to a fixed value (for example, 0) set in step S102 shown in FIG. 4. According to this, frequent setting of the midpoint is suppressed, and simplification of control can be achieved. Instead of counting a predetermined time with a timer, the control device 20 may execute the midpoint learning process when it is determined that there is no vibration input to the vehicle 1 even if the number of times it is determined that there is no vibration input to the vehicle 1 continues for a preset predetermined number of times, and set the midpoint to a fixed value (for example, 0) set in step S102 shown in FIG. 4. Similarly to the above, simplification of control can be achieved.

[0054] Returning to FIG. 4, after the midpoint learning process in step S104, the process proceeds to the abnormality determination process in step S105, and the control device 20 performs an abnormality determination of the electric actuator 12 in the abnormality determination unit 23 when the vehicle 1 is running. The flowchart of this abnormality determination process is shown in FIG. 6.

[0055] In the abnormality determination process, first, in step S301, the control device 20 determines whether the stroke amount (stroke position X N ) from the midpoint of the electric actuator 12 calculated from the detected value of the resolver S1 exceeds a preset upper limit threshold value X Hi . If it is determined that the stroke amount (stroke position X N ) does not exceed the upper limit threshold value X Hi (step S301: NO), it is determined that there is no excess on the tensile side of the stroke amount, and the process proceeds to step S302.

[0056] In step S302, the control device 20 determines whether the stroke amount (stroke position X N ) from the midpoint of the electric actuator 12 calculated from the detected value of the resolver S1 is lower than a preset lower limit threshold value XLo Determine whether it falls below this value. Stroke amount (stroke position X N ) is the lower threshold X Lo If it is determined that the value is not below the specified threshold (step S302: NO), it is determined that there is no excess compression on the stroke amount, and the process proceeds to step S303.

[0057] In step S303, the control device 20 determines that there is no abnormality in the stroke amount (stroke position) of the electric actuator 12, and in the following step S304, the control device 20 determines that the control of the motor 13 is enabled. Therefore, the operation control of the electric actuator 12 is continued.

[0058] On the other hand, in step S301, the stroke amount from the midpoint (stroke position X N ) is the upper threshold X Hi If it is determined that there is an excess on the tensile side of the stroke amount, and in step S302, the stroke amount from the midpoint (stroke position X N ) is the lower threshold X Lo If the value falls below a certain level and it is determined that there is an excess of the stroke amount on the compression side (step S302: YES), the process proceeds to step S305.

[0059] In step S305, the control device 20 determines that there is an abnormality in the stroke amount of the electric actuator 12, and in the following step S306, the control device 20 decides to stop the motor 13. Then, in step S307, the control device 20 controls the short circuit 16 via the drive circuit 14 and inverter 15 in the output control unit 24, and performs a short circuit relay process on the motor's three-phase wires to forcibly stop the motor 13. When the motor 13 stops, a warning is displayed (including a warning sound) on, for example, the instrument panel inside the vehicle 1. This prevents malfunction of the electric actuator 12. However, if a physical failure occurs in the electric actuator 12, and the control device 20 can diagnose the extent of the failure, the electric actuator 12 may be used to the minimum extent necessary, depending on the extent of the failure.

[0060] The motor control stop process will continue until the ignition of vehicle 1 is turned OFF. During this time, a warning display (including a warning sound) will continue to be displayed on the instrument panel inside vehicle 1. Furthermore, the warning display (including a warning sound) may continue even if the ignition of vehicle 1 is turned ON again after being turned OFF.

[0061] Stroke amount of electric actuator 12 (stroke position X N ) Upper threshold X Hi and lower threshold X Lo The upper and lower design values ​​of the stroke amount of the electric actuator 12 can be used as a reference, and a safety factor can be added as needed. Upper threshold X Hi and lower threshold X Lo The stroke amounts are not limited to being set to the same amount on the tension side and compression side with respect to the midpoint, but may also be set to different stroke amounts.

[0062] The control device 20, in the abnormality determination unit 23, determines the stroke amount (stroke position X) of any one of the four first electric actuators 12A to the fourth electric actuator 12D. N Regarding the upper threshold X, Hi The threshold X is greater than or equal to the lower threshold X. Lo If it is determined that the value falls below a certain level, the control of the motor 13 may also be stopped for the electric actuators 12 corresponding to the other wheels TR adjacent to the left, right, front, or rear of the wheel TR corresponding to the one electric actuator 12. This is because it is highly likely that a similar abnormality (failure) has occurred in the electric actuators 12 other than the one that was detected as abnormal. This stabilizes the behavior of the vehicle 1 more than stopping the control of the electric actuator 12 corresponding to only one of the four wheels TR, thereby reducing the discomfort caused to the occupants.

[0063] Furthermore, in the abnormality determination unit 23, the control device 20 determines that the stroke amount (stroke position) of the electric actuator 12 is above the upper threshold X. Hi The threshold X is greater than or equal to the lower threshold X.Lo If it is determined that the speed falls below a certain level, the output control unit 24 may output a signal to limit the vehicle speed, for example, to 60 km / h or less. This can improve the safety of the vehicle 1 while it is in operation.

[0064] Returning to Figure 4, if it is determined in step S101 that the system is not starting (the resolver electrical angle value and stroke amount value have already been set in the flowchart processing one step prior and are available as the previous values) (step S101: NO), the process proceeds to step S106. In step S106, the control device 20, in the stroke amount calculation unit 21, detects the rotation angle (electrical angle) θ of the resolver S1. N This is the previous value, i.e., the previous detected value θ. N-1 Set to this.

[0065] Next, in step S107, the control device 20 receives the detected value θ of the rotation angle (electrical angle) from the resolver S1. N The current value is set, and then in step S108, the amount of change in the rotation angle (electrical angle) of the resolver S1 is calculated. That is, as shown in Figure 7, when the electric actuator 12 performs a stroke operation, the detected value of the rotation angle (electrical angle) of the resolver S1 changes between 0 and 360 degrees. The control device 20 uses the previous value θ, which is the previously detected value of the rotation angle (electrical angle) of the resolver S1, as the amount of change in the rotation angle (electrical angle) of the resolver S1. N-1 And this time the value θ N The difference Δθ = θ N -θ N-1 Calculate.

[0066] Next, in step S109, the control device 20 performs a crossover determination process between 360 degrees and 0 degrees. Specifically, if the Δθ obtained in step S107 is -180 degrees or less, the control device 20 sets Δθ = Δθ + 360, and if Δθ is 180 degrees or more, it sets Δθ = Δθ - 360. Then, in step S110, the control device 20 sets the previous value X of the stroke amount (stroke position). N-1 =X NSet it as follows.

[0067] Next, in step S111, the control device 20 sets the current value X of the stroke amount (stroke position) of the electric actuator 12. N =X N-1 +K·Δθ is calculated. K is a coefficient determined from the number of pole pairs of the motor 13, the specifications of the ball screw shaft 125, etc. After that, the process moves to the process from step S104 described above, and the control device 20 performs an abnormality determination process after the midpoint learning process using the midpoint learning unit 22 and the abnormality determination unit 23.

[0068] As described above, according to the electric suspension device 10 and electric suspension control method of this embodiment, the stroke amount (stroke position) of the electric actuator is calculated using a rotation angle sensor such as a resolver S1, which is generally located on the motor 13 of the electric actuator 12. Therefore, there is no need to install additional sensors, and the system configuration of the electric suspension device 10 can be simplified while improving the measurement accuracy of the stroke amount (stroke position) of the electric actuator 12.

[0069] By the way, in the flowchart shown in Figure 4, the control device 20 includes a step S101 to determine whether it is system startup time after the ignition of vehicle 1 is turned ON. However, as shown in the flowchart in Figure 8, the control device 20 may execute the processes of steps S401 to S408 after the ignition of vehicle 1 is turned ON without determining whether it is system startup time. In this case, the control device 20 always sets the calculated value of the stroke amount at the time of the previous system shutdown, which is calculated from the detected value of the electrical angle of resolver S1 at the time of the previous system shutdown, as the value of the stroke amount (stroke position) of the electric actuator 12 when the ignition of vehicle 1 is turned ON, thereby improving the accuracy of the stroke amount (stroke position) calculation.

[0070] In the flowchart shown in Figure 8, steps S401 to S406, S407, and S408 are the same processes as steps S106 to S111, S104, and S105 in the flowchart shown in Figure 4. Therefore, the explanations for these steps will be based on those in Figure 4, and their explanations here will be omitted.

[0071] The electric suspension device 10 and the control method for the electric suspension of this embodiment provide the following effects.

[0072] The electric suspension device 10 of this embodiment is an electric suspension device mounted on a vehicle 1, and comprises an electric actuator 12 that performs stroke operation according to the behavior of the vehicle 1, a motor 13 that drives the electric actuator 12, a resolver S1 which is a rotation angle sensor that detects the rotation angle of the motor 13, and a control device 20 that controls the electric actuator 12. The control device 20 calculates the stroke amount of the electric actuator 12 based on the change in the rotation angle of the resolver S1, and controls the electric actuator 12 based on the calculated stroke amount.

[0073] According to this, the stroke amount of the electric actuator 12 can be calculated using a rotation angle sensor such as a resolver S1, which is generally located on the motor 13 of the electric actuator 12. Therefore, the system configuration of the electric suspension device 10 can be simplified or omitted while improving the measurement accuracy of the stroke amount of the electric actuator 12.

[0074] The control device 20 may set the stroke amount of the electric actuator 12 when the electric suspension device 10 is started to a fixed initial value.

[0075] According to this, the control of the electric suspension device 10 can be simplified because the system does not carry over the last value from the previous system startup.

[0076] The control device 20 may set the stroke amount of the electric actuator 12 at startup of the electric suspension device 10 to the value at the time of the previous shutdown of the electric suspension device 10.

[0077] According to this, the accuracy of calculating the stroke amount of the electric actuator 12 can be improved.

[0078] The control device 20 may further include vibration detection sensors (resolver S1, sprung mass G sensor S2, body roll rate sensor S3, body pitch rate sensor S4, and vehicle speed sensor S5) for detecting vibrations of the vehicle 1, and may set the stroke amount of the electric actuator 12 to a fixed value when the control device 20 determines that there are no vibrations in the vehicle 1 based on the detection results of the vibration detection sensors.

[0079] According to this, it is possible to respond to changes in the state of the vehicle 1, such as increases or decreases in the number of occupants or cargo load, after the electric suspension system 10 has been activated, and to measure the stroke amount of the electric actuator 12 with higher precision.

[0080] The control device 20 may set the stroke amount of the electric actuator 12 to a fixed value if it determines, based on the detection results of the vibration detection sensor, that there is no vibration in the vehicle 1 for a predetermined number of times or for a predetermined period of time.

[0081] This reduces the need to frequently set fixed values, thus further simplifying the control of the electric suspension system 10.

[0082] The control device 20 sets the calculated stroke amount to a predetermined value (upper threshold X). Hi ) exceeds or exceeds a predetermined value (lower threshold X Lo If the value falls below this level, control of the electric actuator 12 may be stopped.

[0083] This makes it possible to prevent malfunctions of the electric actuator 12.

[0084] The electric actuators 12 are provided on each of the multiple wheels TR of the vehicle 1, and the control device 20 controls the stroke amount of the electric actuator 12 corresponding to one wheel TR among the multiple electric actuators (first electric actuator 12A to fourth electric actuator 12D) to a predetermined value (upper threshold X). Hi ) exceeds or exceeds a predetermined value (lower threshold X Lo If the value falls below this level, control of the electric actuator 12 corresponding to the wheel TR adjacent to the wheel TR in question or to all wheel TRs may be stopped.

[0085] According to this, the behavior of the vehicle 1 is more stable and the discomfort caused to the occupants is reduced compared to when the control of the electric actuator 12 corresponding to only one of the multiple wheels TR is stopped.

[0086] The control device 20 controls the stroke amount of the electric actuator 12 to a predetermined value (upper threshold X). Hi ) exceeds or exceeds a predetermined value (lower threshold X Lo If the speed falls below a certain level, a signal to limit the vehicle speed may be output.

[0087] According to this, the safety of vehicle 1 during operation can be improved.

[0088] The electric suspension control method of this embodiment is a control method for an electric suspension equipped with an electric actuator 12 mounted on a vehicle 1 that performs stroke operation according to the behavior of the vehicle 1, and calculates the stroke amount of the electric actuator 12 based on the amount of change in the rotation angle of a resolver S1, which is a rotation angle sensor that detects the rotation angle of a motor 13 that drives the electric actuator 12, and controls the electric actuator 12 based on the calculated stroke amount.

[0089] According to this, the stroke amount of the electric actuator 12 can be calculated using a rotation angle sensor such as a resolver S1, which is generally located on the motor 13 of the electric actuator 12. Therefore, the system configuration of the electric suspension device 10 can be simplified or omitted while improving the measurement accuracy of the stroke amount of the electric actuator 12.

[0090] The processing units in the flowcharts shown in Figures 4-6 and 8 are divided according to their main processing content to facilitate understanding of the processing of the control device 20 of the electric suspension system 10. The method of dividing and naming of the processing units shown in each flowchart does not limit the embodiments. The processing of the control device 20 can be further divided into more processing units depending on the processing content, or it can be divided so that one processing unit contains even more processing. The processing order in the flowcharts above is not limited to the examples shown.

[0091] The control method of the electric suspension system 10 by the control device 20 can be realized by having the processor 20B of the control device 20 execute a control program corresponding to the control method of the control device 20. The control program can be stored on a recording medium that is readable by a computer. The recording medium can be a magnetic, optical, or semiconductor memory device. Specifically, examples include portable or fixed recording media such as flexible disks, CD-ROMs (Compact Disk Read Only Memory), DVDs (Digital Versatile Discs), Blu-ray® Discs, magneto-optical disks, flash memory, and card-type recording media. The recording medium may also be a non-volatile storage device such as RAM, ROM, or HDD, which are internal storage devices of the electric suspension system 10. The control program corresponding to the control method of the electric suspension system 10 by the control device 20 can be stored on a server device or the like, and the control method of the control device 20 can be realized by downloading the control program from the server device to the control device 20. [Explanation of Symbols]

[0092] 1 vehicle 10 Electric suspension system 12 Electric Actuators 13 Motors 20 Control device S1 resolver (rotation angle sensor, vibration detection sensor) S2, S2A~S2D Sprung G-sensor (Vibration detection sensor) S3 Vehicle Roll Rate Sensor (Vibration Detection Sensor) S4 Vehicle body pitch rate sensor (vibration detection sensor) S5 Vehicle Speed ​​Sensor TR wheels X Hi Upper threshold X Lo Lower threshold

Claims

1. An electric suspension system mounted on a vehicle, An electric actuator that performs a stroke operation according to the behavior of the vehicle, A motor that drives the aforementioned electric actuator, A rotation angle sensor for detecting the rotation angle of the motor, The system comprises a control device for controlling the electric actuator, The electric actuator is provided on each of the multiple wheels of the vehicle. The control device calculates the stroke amount of the electric actuator based on the change in rotation angle of the rotation angle sensor, controls the electric actuator based on the calculated stroke amount, and stops controlling the electric actuators corresponding to the wheels adjacent to the wheel or all of the wheels when the stroke amount of the electric actuator corresponding to one of the multiple electric actuators exceeds a predetermined upper limit or falls below a predetermined lower limit.

2. An electric suspension system mounted on a vehicle, An electric actuator that performs a stroke operation according to the behavior of the vehicle, A motor that drives the aforementioned electric actuator, A rotation angle sensor for detecting the rotation angle of the motor, The system comprises a control device for controlling the electric actuator, The control device calculates the stroke amount of the electric actuator based on the change in rotation angle of the rotation angle sensor, controls the electric actuator based on the calculated stroke amount, and stops controlling the electric actuator and outputs a signal to limit the vehicle speed when the calculated stroke amount exceeds a predetermined upper limit or falls below a predetermined lower limit.

3. The electric suspension device according to claim 1 or 2, wherein the control device sets the stroke amount of the electric actuator at startup of the electric suspension device to a fixed initial value.

4. The electric suspension device according to claim 1 or 2, wherein the control device sets the stroke amount of the electric actuator at startup of the electric suspension device to the value at the previous shutdown of the electric suspension device.

5. The vehicle further comprises a vibration detection sensor for detecting vibrations of the vehicle, The electric suspension device according to claim 1 or 2, wherein the control device determines, based on the detection result of the vibration detection sensor, that there is no vibration in the vehicle, and sets the stroke amount of the electric actuator to a fixed value.

6. The electric suspension device according to claim 5, wherein the control device determines, based on the detection result of the vibration detection sensor, that there is no vibration of the vehicle for a predetermined number of times or for a predetermined period of time, and sets the stroke amount of the electric actuator to a fixed value.

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