Vehicle suspension control system

Abstract

To provide a vehicular suspension control device that can quickly and seamlessly transfer ride comfort control and steering stability control.SOLUTION: In a suspension ECU 10, an adjusting part 13 compares a first control amount A1 for enabling a shock absorber 5 to generate damping force in accordance with ride comfort control of damping vibration of a spring upper member caused by unevenness of a road surface with a second control amount A2 for enabling the shock absorber 5 to generate damping force in accordance with steering stability control of damping vibration of the spring upper member caused by behavior change occurring on the spring upper member, so as to determine which of the first control amount A1 and the second control amount A2 is larger. Further, in the suspension ECU 10, a damping force control part 14 makes the shock absorber 5 generate damping force on the basis of the first control amount A1 or the second control amount A2 which is determined to be larger by the adjusting part 13.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a vehicle suspension control device.

Background Art

[0002] Conventionally, for example, a damping force control device for a vehicle (hereinafter referred to as "conventional control device") disclosed in Patent Document 1 is known. The conventional control device determines whether the vehicle is going straight or turning based on the magnitude of the steering angle and the steering angular velocity. Then, when it is determined that the vehicle is going straight, the conventional control device outputs a control amount calculated by skyhook control calculation, and when it is determined that the vehicle is turning, the conventional control device outputs a control amount calculated by turning damping force control calculation. Further, when it is determined that the turning state is converging, the conventional control device makes a transition from turning damping force control calculation to skyhook control calculation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional control device, it is determined whether the vehicle is turning or not, and based on the determination result, ride comfort control using a control amount by skyhook control calculation and steering stability control using a control amount by turning damping force control calculation are selected and switched, and the control amount used in the selected control is output. In this case, in the conventional control device, there is room for improvement in terms of taking time for conformity of a determination value or the like for smoothly changing the control amount when selecting and switching between ride comfort control and steering stability control, and maintaining the consistency of vehicle behavior.

[0005] The purpose of this disclosure is to provide a vehicle suspension control device that can quickly and seamlessly transition between ride comfort control and handling stability control. [Means for solving the problem]

[0006] The vehicle suspension control device of this disclosure comprises: a damping force control unit that generates a damping force in a shock absorber which is arranged corresponding to each wheel and constitutes a suspension device connecting the unsprung member and the sprung member of the vehicle, so as to dampen vibrations occurring in the sprung member; a first control amount which generates a damping force in the shock absorber according to ride comfort control which dampens vibrations of the sprung member caused by unevenness of the road surface input from the road surface on which the vehicle travels via the unsprung member; and a second control amount which generates a damping force in the shock absorber according to steering stability control which dampens vibrations of the sprung member caused by changes in the behavior of the sprung member according to the driving state of the vehicle, and an arbitration unit which determines which of the first control amount and the second control amount is larger by comparing the magnitudes of each of these, and the damping force control unit generates a damping force in the shock absorber based on the first control amount or the second control amount which the arbitration unit determines to be larger. [Effects of the Invention]

[0007] According to the vehicle suspension control device of this disclosure, the arbitration unit can compare the magnitude of a first control variable used in ride comfort control with the magnitude of a second control variable used in steering stability control, and output the first or second control variable, whichever is determined to be larger, to the damping force control unit. As a result, the vehicle suspension control device can transition quickly and seamlessly between ride comfort control and steering stability control. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a vehicle capable of being equipped with a vehicle suspension control device. [Figure 2] This is a schematic cross-sectional view of a shock absorber. [Figure 3]Figure 1 is a functional block diagram of the vehicle suspension control device. [Figure 4] This is a diagram explaining the mediation department. [Figure 5] This diagram illustrates how the control variable is changed by the modification unit. [Figure 6] This diagram illustrates how the control amount of the modification unit changes in response to the determination made by the determination unit. [Modes for carrying out the invention]

[0009] Hereinafter, a vehicle suspension control device, which is one embodiment of the present disclosure, will be described in detail with reference to the drawings. In addition to the embodiment described below, the vehicle suspension control device can be implemented in various forms with various modifications based on the knowledge of those skilled in the art.

[0010] The vehicle suspension control device is applied to the vehicle 1 shown in Figure 1. The vehicle 1 may be driven manually by a driver or automatically. The embodiments described below will illustrate the case where the vehicle 1 is driven manually by a driver.

[0011] Vehicle 1 is equipped with four independent suspension devices 3, each corresponding to one of the front, rear, left, and right wheels 2. Each suspension device 3 is positioned between a suspension lower arm (not shown) that holds the wheel 2 and forms part of the unsprung member, and a mount (not shown) provided on the vehicle body (not shown) and forming part of the sprung member. In this way, each suspension device 3 connects the unsprung member and the sprung member.

[0012] Each suspension device 3 includes a coil spring 4 and a hydraulic shock absorber 5 (hereinafter simply referred to as "shock absorber 5"). In the suspension device 3, the coil spring 4 and the shock absorber 5 are arranged in parallel to each other between the unsprung member and the sprung member.

[0013] As shown in Figure 2, the shock absorber 5 is composed mainly of a cylinder 51 and a linear solenoid unit 52. This allows the shock absorber 5 to generate a damping force that can be adjusted according to the vibration state of the sprung mass member to dampen vibrations occurring in the sprung mass member. The structure and operation of the hydraulic shock absorber 5 are well known; for example, refer to Japanese Patent Publication No. 11-115439 and Japanese Patent Publication No. 2015-140846. Therefore, the structure and operation of the shock absorber 5 will be briefly described below.

[0014] The cylinder 51 comprises a housing 53, a piston 54 positioned to be movable in the vertical direction, and a rod 55 connected to the piston 54 and extending upward from the housing 53. The housing 53 has a main tube 531, an outer tube 532, and an inner tube 533. Inside the main tube 531, the piston 54 divides the space into a first fluid chamber 534 and a second fluid chamber 535. A buffer chamber 536 for containing working fluid is also divided between the main tube 531 and the outer tube 532.

[0015] Furthermore, an annular liquid passage 537 is formed between the inner surface of the inner tube 533 and the outer surface of the main tube 531. In addition, a flow hole 538 is provided at the top of the main tube 531 to allow the working fluid to flow between the first liquid chamber 534 and the liquid passage 537.

[0016] Furthermore, an outlet 521 is provided at the lower part of the inner tube 533 to allow the working fluid to flow out from the fluid passage 537 to the linear solenoid unit 52. In addition, an inlet 522 is provided in the outer tube 532 to allow the working fluid to flow from the linear solenoid unit 52 to the buffer chamber 536.

[0017] The linear solenoid unit 52 is arranged so as to cover the outlet 521 and the inlet 522. Thereby, the linear solenoid unit 52 allows the working fluid flowing out from the first liquid chamber 534 and flowing into the buffer chamber 536 through the liquid passage 537 to pass through, and exhibits a function of imparting resistance to the flow of the passing working fluid.

[0018] The linear solenoid unit 52 is mainly composed of a main valve 523 for imparting resistance to the passing working fluid and a pilot valve 524 for adjusting the opening pressure of the main valve 523. The pilot valve 524 has a solenoid, and is configured such that the larger the current supplied to the solenoid, the smaller the valve opening degree. Thereby, the opening pressure of the main valve 523 depends on the magnitude of the current supplied to the solenoid of the pilot valve 524, and the larger the current, that is, the smaller the valve opening degree of the pilot valve 524, the higher it becomes. Therefore, in the linear solenoid unit 52, the higher the opening pressure of the main valve 523, the greater the resistance imparted to the passing working fluid.

[0019] Also, the shock absorber 5 (more specifically, the cylinder 51) includes a base valve 56 that partitions the bottom of the second liquid chamber 535, that is, separates the second liquid chamber 535 and the buffer chamber 536, at the inner bottom of the main tube 531. The base valve 56 is configured to allow the flow of the working fluid between the second liquid chamber 535 and the buffer chamber 536 and to be able to impart resistance to the flow of the working fluid.

[0020] A plurality of connecting passages for connecting the second liquid chamber 535 and the buffer chamber 536 are provided concentrically in the valve body 561 of the base valve 56. A valve plate 562 made of an elastic material is disposed on the lower surface of the valve body 561, and the connecting passage on the inner peripheral side of the valve body 561 is blocked by the valve plate 562. Thereby, when the valve plate 562 is deflected by the hydraulic pressure difference between the second liquid chamber 535 and the buffer chamber 536, the flow of the working fluid from the second liquid chamber 535 to the buffer chamber 536 is allowed.

[0021] Also, on the upper surface of the valve body 561, two valve plates 563 and 564 made of an elastic material are arranged. And, the connection passage on the inner peripheral side of the valve body 561 is not constantly blocked by the openings provided in the valve plates 563 and 564, and the connection passage on the outer peripheral side of the valve body 561 is blocked by the valve plate 564. Thus, when the valve plate 564 is deflected by the hydraulic pressure difference between the second liquid chamber 535 and the buffer chamber 536, the flow of the working fluid from the buffer chamber 536 to the second liquid chamber 535 is allowed.

[0022] Also, between the lower surface of the valve body 561 and the bottom surface of the main tube 531, a cylindrical member 565 is fixed so as to sandwich the valve plate 562 between the valve body 561. A rotatable rotor 566 is inserted inside the cylindrical member 565. The rotor 566 is rotationally driven by a motor 567 disposed outside the bottom surface of the outer tube 532.

[0023] A through hole penetrating from the inside to the outside is formed in the cylindrical member 565. Also, a slit that penetrates from the inside to the outside, extends in the circumferential direction, and has a shape whose width is gradually narrowed is formed in the rotor 566. And, the through hole of the cylindrical member 565 and the slit of the rotor 566 overlap in the radial direction, and in the overlapping state, the inside of the rotor 566 and the outside of the cylindrical member 565 are communicated. Also, a through hole penetrating in the axial direction is formed in the central portion of the valve body 561, the upper end of which opens to the second liquid chamber 535, and the lower end of which opens to the inside of the cylindrical member 565.

[0024] In other words, the second liquid chamber 535 and the buffer chamber 536 are connected by the through-hole in the cylindrical member 565, the slit in the rotating body 566, the inside of the rotating body 566, the inside of the cylindrical member 565, and the through-hole in the valve body 561. The gap formed by the through-hole in the cylindrical member 565 and the slit in the rotating body 566 functions as a throttle, providing resistance to the flow of working fluid between the second liquid chamber 535 and the buffer chamber 536. Therefore, when the motor 567 rotates the rotating body 566, the opening area formed by the through-hole in the cylindrical member 565 and the slit in the rotating body 566 is changed, thereby changing the resistance to the flow of working fluid.

[0025] The cylinder 51 has its lower end connected to the unsprung member at the housing 53 and its upper end connected to the sprung member at the rod 55. As a result, the cylinder 51 extends when the unsprung member and the sprung member move relative to each other in a direction that separates them, and contracts when the unsprung member and the sprung member move relative to each other in a direction that brings them closer together.

[0026] In the shock absorber 5, as described above, the greater the current supplied to the solenoid of the linear solenoid unit 52, the higher the opening pressure of the main valve 523. As a result, the damping force against the expansion and contraction of the cylinder 51 increases. Also, in the shock absorber 5, as described above, the smaller the opening area formed by the through hole of the cylindrical member 565 and the slit of the rotating body 566, the greater the resistance to the flow of the working fluid. As a result, the damping force against the expansion and contraction of the cylinder 51 increases.

[0027] Returning to Figure 1, the vehicle 1 is equipped with a steering device 6. In this embodiment, the steering device 6 is configured to steer the left and right front wheels 2. It is also possible for the steering device 6 to be configured to steer the left and right rear wheels 2 in addition to the left and right front wheels 2. Furthermore, the vehicle 1 is configured so that the left and right front wheels 2, the left and right rear wheels 2, or all four wheels 2 (front, rear, left, and right) are driven by a driving force from a power source (engine or electric motor, etc.) which is not shown.

[0028] Furthermore, the vehicle 1 is equipped with a brake electronic control unit 7 (hereinafter sometimes referred to as "brake ECU 7") that controls the braking force generated by a braking device (not shown) on each of the wheels 2. The brake ECU 7 is mainly composed of a computer device equipped with a CPU, ROM, RAM, and various interfaces. The brake ECU 7 is connected to the suspension electronic control unit 10 and the vehicle speed sensor 84, which will be described later.

[0029] Furthermore, vehicle 1 is equipped with a sensor group 8. As shown in Figure 1, the sensor group 8 includes a sprung mass acceleration sensor 81 and a steering angle sensor 82. The sensor group 8 also includes a motor rotation angle sensor 83 and a vehicle speed sensor 84.

[0030] The sprung mass acceleration sensor 81 is a sensor that detects the vibration state of the sprung mass members of the vehicle 1 and detects the vertical acceleration Gz of the sprung mass members corresponding to each wheel 2. The steering angle sensor 82 is a sensor that detects the driving state (turning state) of the vehicle 1 and detects the steering angle δ of the steering wheels (for example, the left and right front wheels 2). The motor rotation angle sensor 83 detects the motor rotation angle θ of the motors 567 of each shock absorber 5. The vehicle speed sensor 84 is a sensor that detects the driving state of the vehicle 1 and detects the vehicle speed V, which is the driving speed of the vehicle 1.

[0031] Vehicle 1 is equipped with a suspension electronic control unit 10 (hereinafter referred to as "suspension ECU 10") as a vehicle suspension control device. The suspension ECU 10 is mainly composed of a computer device equipped with a CPU, ROM, RAM, and various interfaces. The CPU sequentially executes predetermined programs and performs data reading, numerical calculations, and output of calculation results. The ROM stores programs and maps executed by the CPU. The RAM temporarily stores data, etc. The various interfaces are connected to each of the sensor group 8 and the brake ECU 7. As shown in Figure 3, the suspension ECU 10 mainly comprises a ride comfort control unit 11, a steering stability control unit 12, a mediation unit 13, and a damping force control unit 14.

[0032] The ride comfort control unit 11 operates the shock absorber 5 to reduce vertical vibrations generated in the vehicle body, which is the sprung mass, due to irregularities in the road surface input from the road surface on which the vehicle 1 travels via the wheels 2, which are the unsprung mass, thereby performing control to improve the ride comfort perceived by the occupants. The ride comfort control unit 11 acquires the vertical acceleration Gz of the sprung mass from each of the four sprung mass acceleration sensors 81. Based on the acquired vertical acceleration Gz, the ride comfort control unit 11 outputs a first control amount A1 to the arbitration unit 13 to generate a damping force in the shock absorber 5 in order to reduce the vibration state of the sprung mass and improve the ride comfort.

[0033] Furthermore, the ride comfort control unit 11 is equipped with a determination unit 111. Based on the vertical acceleration Gz obtained from each of the sprung mass acceleration sensors 81, the determination unit 111 determines whether a first vibration state C1 occurs in which the sprung mass vibrates at a low vibration frequency, or whether a second vibration state C2 occurs in which the sprung mass vibrates at medium and high vibration frequencies (see Figure 5). When the sprung mass vibrates at medium and high vibration frequencies, the occupants usually perceive a deterioration in ride comfort. The determination unit 111 then outputs vibration information F, indicating that the second vibration state C2 has occurred, to the modification unit 124 of the steering stability control unit 12, which will be described later.

[0034] The steering stability control unit 12 operates the shock absorber 5 to dampen vibrations caused by changes in behavior of the vehicle body, which is a sprung mass member, in response to steering and braking as the driving state of the vehicle 1, thereby performing control to ensure the steering stability of the vehicle 1. The steering stability control unit 12 includes a steering control unit 121, an anti-pitch control unit 122, a maximum value determination unit 123, and a modification unit 124.

[0035] The steering control unit 121 acquires the steering angle δ detected by the steering angle sensor 82. The steering control unit 121 then outputs a control amount A211 to the maximum value determination unit 123 to generate a damping force in the shock absorber 5 to dampen vibrations caused by roll behavior in the vehicle body (sprung mass) of the vehicle 1, which is in a turning state due to the steering angle δ, as a driving state of the vehicle 1.

[0036] The anti-pitch control unit 122 obtains the requested deceleration Dt from the brake ECU 7. The anti-pitch control unit 122 then outputs a control amount A212 to the maximum value determination unit 123 to generate a damping force in the shock absorber 5 to dampen vibrations caused by pitch behavior in the vehicle body (sprung mass) of the vehicle 1 when it is decelerating according to the requested deceleration Dt, for example. The anti-pitch control unit 122 can also output a control amount A212 to the maximum value determination unit 123 to dampen vibrations caused by pitch behavior in the vehicle body (sprung mass) of the vehicle 1 when it is accelerating according to the requested acceleration, for example.

[0037] The maximum value determination unit 123 compares the magnitude of the control amount A211 output from the steering control unit 121 with the magnitude of the control amount A212 output from the anti-pitch control unit 122. The maximum value determination unit 123 then outputs the control amount A211 or control amount A212, whichever is larger, as control amount A21 to the modification unit 124. If the magnitudes of control amount A211 and control amount A212 are the same, the maximum value determination unit 123 outputs, for example, control amount A211 as control amount A21 to the modification unit 124.

[0038] The modification unit 124 obtains the control variable A21 from the maximum value determination unit 123 and outputs a second control variable A2 to the arbitration unit 13, which is either a modified version of the obtained control variable A21 or a version without modification of the control variable A21. When ride comfort control is prioritized, the modification unit 124 modifies the size of the second control variable A2 so that it is smaller than the size of the first control variable A1. When handling stability control is prioritized, the modification unit 124 modifies the second control variable A2 so that it is larger than the size of the first control variable A1. Here, the modification unit 124 modifies the second control variable A2 by increasing the base B of the obtained control variable A21 by an increase amount B1 or decreasing it by a decrease amount B2 (see Figure 5).

[0039] Furthermore, the modification unit 124 can change the magnitude of the controlled variable A21, i.e., the second controlled variable A2, by, for example, increasing the controlled variable A21 by multiplying it by a coefficient greater than "1", or decreasing the controlled variable A2 by multiplying it by a coefficient less than "1". In addition, the modification unit 124 can also change the magnitude of the controlled variable A21, i.e., the second controlled variable A2, by, for example, adding an increase amount B1 to the peak value of the controlled variable A21, or subtracting a decrease amount B2 from the peak value of the controlled variable A21.

[0040] Furthermore, the modification unit 124 of this embodiment acquires vibration information F from the determination unit 111 of the ride comfort control unit 11. Based on the vibration information F, the modification unit 124 modifies the second control amount A2 (control amount A21) to decrease in magnitude depending on the situation in which the second vibration state C2 occurs (see Figure 6). That is, in the situation in which vibration information F is output, i.e., the second vibration state C2 occurs in which the vehicle body, which is a sprung mass member, vibrates at medium and high frequencies, resulting in a deterioration of ride comfort, ride comfort control takes precedence over steering stability control. For this reason, regardless of the priority between ride comfort control and steering stability control, the modification unit 124 modifies the second control amount A2 (control amount A21) by decreasing it by, for example, a reduction amount B3 (see Figure 6).

[0041] The arbitration unit 13 compares the magnitudes of the first control variable A1 output from the ride comfort control unit 11 and the second control variable A2 output from the steering stability control unit 12 to determine which of the two is larger. If the magnitude of the first control variable A1 is larger than the magnitude of the second control variable A2, the arbitration unit 13 outputs the first control variable A1 to the damping force control unit 14 in order to prioritize ride comfort control. If the magnitude of the second control variable A2 is larger than the magnitude of the first control variable A1, the arbitration unit 13 outputs the second control variable A2 to the damping force control unit 14 in order to prioritize steering stability control.

[0042] The damping force control unit 14 obtains the first control amount A1 or the second control amount A2 from the arbitration unit 13. Then, the damping force control unit 14 generates a predetermined damping force in the shock absorber 5 based on a target value set according to the first control amount A1 or the second control amount A2.

[0043] Specifically, the damping force control unit 14 sets a target current to be supplied to the linear solenoid unit 52 in order to change the opening pressure of the main valve 523 of the shock absorber 5, based on the first control amount A1 or the second control amount A2. Then, the damping force control unit 14 supplies the target current to the solenoid of the linear solenoid unit 52 via a battery and drive circuit (not shown) to control the damping force of the shock absorber 5.

[0044] Furthermore, the damping force control unit 14 sets a target rotation angle to rotate the motor 567 of the shock absorber 5, that is, to change the opening area formed by the through hole of the cylindrical member 565 and the slit of the rotating body 566, based on the first control amount A1 or the second control amount A2. The motor 567 is, for example, a stepping motor. The damping force control unit 14 then rotates the motor 567 to the target rotation angle while obtaining the motor rotation angle θ from the motor rotation angle sensor 83, and controls the damping force of the shock absorber 5.

[0045] Next, the operation of the suspension ECU 10 will be explained with reference to Figures 4, 5, and 6. As described above, the ride comfort control unit 11 outputs a first control variable A1 to the arbitration unit 13. Here, the first control variable A1 is a control variable obtained by adding a control variable A11 for reducing the vertical acceleration Gz detected by the sprung mass acceleration sensor 81, i.e., the vertical vibration of the sprung mass member, and a base control variable A12 that is pre-set for executing ride comfort control and stored, for example, in ROM. Furthermore, in the ride comfort control unit 11, if a second vibration state C2 occurs based on the vertical acceleration Gz detected by the determination unit 111, vibration information F is output to the modification unit 124 of the steering stability control unit 12.

[0046] The modification unit 124 obtains the control variable A21 from the maximum value determination unit 123. The modification unit 124 also obtains the increase amount B1, decrease amount B2, and decrease amount B3 stored in, for example, a ROM. Then, for example, in situations where steering stability control is prioritized, the modification unit 124 increases the base B of the control variable A21 by the increase amount B1, as shown by the dashed line in Figure 5, and in situations where ride comfort control is prioritized, it decreases the base B of the control variable A21 by the decrease amount B2, as shown by the double dashed line in Figure 5. The modification unit 124 then outputs the second control variable A2, which has been modified by increasing or decreasing the control variable A21, to the arbitration unit 13. Alternatively, the modification unit 124 can output the control variable A21 obtained from the maximum value determination unit 123 as the second control variable A2 without increasing or decreasing it.

[0047] Furthermore, when the modification unit 124 acquires vibration information F from the determination unit 111, it outputs a control amount A21, i.e., the second control amount A2, to the arbitration unit 13, which is obtained by subtracting a reduction amount B3, pre-stored in ROM or the like, from the modified control amount A21 (second control amount A2), as shown by the dashed and solid lines in Figure 6. As a result, as shown in Figure 6, when a second vibration state C2 that worsens ride comfort occurs, the control amount A21 (second control amount A2) shown by the dashed line is changed to a smaller second control amount A2 shown by the solid line. In other words, when a second vibration state C2 occurs in a situation where both ride comfort control and steering stability control are required simultaneously, ride comfort control takes precedence over steering stability control.

[0048] On the other hand, if the modification unit 124 does not acquire vibration information F from the determination unit 111, that is, if the first vibration state C1 occurs, as shown in Figure 6, it does not subtract the decrease amount B3 from the control amount A21, that is, it outputs the control amount A21 that has been increased or decreased by the increase amount B1 and decrease amount B2 as the second control amount A2 to the arbitration unit 13. In addition, if the first vibration state C1 occurs, the modification unit 124 can also output to the arbitration unit 13 a second control amount A2 that does not increase or decrease the control amount A21, or a second control amount A2 that has been increased and modified.

[0049] As shown in Figure 4, the arbitration unit 13 obtains the first control variable A1 from the ride comfort control unit 11. The arbitration unit 13 also obtains the second control variable A2 from the modification unit 124 of the steering stability control unit 12. The arbitration unit 13 then outputs the control variable that is larger than the first control variable A1 or the second control variable A2 to the damping force control unit 14. In other words, if ride comfort control is prioritized, the arbitration unit 13 outputs the first control variable A1 to the damping force control unit 14 because the magnitude of the first control variable A1 is larger than the magnitude of the second control variable A2. On the other hand, if steering stability control is prioritized, the arbitration unit 13 outputs the second control variable A2 to the damping force control unit 14 because the magnitude of the second control variable A2 is larger than the magnitude of the first control variable A1.

[0050] As a result, the arbitration unit 13 does not need to perform adjustment processing such as selecting and switching between ride comfort control and steering stability control, or determining judgment values ​​for smoothly changing the first control variable A1 and the second control variable A2. Therefore, the arbitration unit 13 can quickly determine the first control variable A1 or the second control variable A2, that is, it can quickly process the arbitration of ride comfort control or steering stability control.

[0051] Furthermore, the arbitration unit 13 compares the magnitude of the first control amount A1 and the magnitude of the second control amount A2 and outputs the larger of the two to the damping force control unit 14. This suppresses the discontinuity in the control amount that occurs when switching between the first control amount A1 and the second control amount A2, that is, the large difference between the first control amount A1 and the second control amount A2. Therefore, by performing arbitration processing in the arbitration unit 13, the ride comfort control and handling stability control are seamlessly transitioned, and as a result, the consistency of the behavior of the vehicle 1 can be maintained.

[0052] Furthermore, when transitioning between ride comfort control and handling stability, the difference between the first control amount A1 and the second control amount A2 can be reduced, thereby reducing the change in the control amount of the shock absorber 5 associated with the transition between ride comfort control and handling stability control. This makes it possible to suppress the generation of control noise that occurs when operating the linear solenoid unit 52 or motor 567 of the shock absorber 5, for example.

[0053] The damping force control unit 14 acquires either a first control variable A1 or a second control variable A2. The damping force control unit 14 then sets a target current and a target rotation angle corresponding to the acquired first control variable A1 or second control variable A2, and controls the supply of the target current to the linear solenoid unit 52 of the shock absorber 5, as well as the motor rotation angle θ of the motor 567. In this way, the damping force control unit 14 can change and control the damping force generated in the shock absorber 5 according to the first control variable A1 or the second control variable A2, that is, according to ride comfort control or handling stability control.

[0054] As can be understood from the above explanation, the suspension ECU 10 as a vehicle suspension control device comprises a damping force control unit 14 that generates a damping force so as to dampen vibrations generated in the sprung mass of the shock absorber 5, which is arranged corresponding to each of the wheels 2 and constitutes a suspension device 3 that connects the unsprung mass and sprung mass of the vehicle 1, and a first control amount A1 that generates a damping force in the shock absorber 5 according to ride comfort control that dampens vibrations of the sprung mass caused by unevenness in the road surface input from the road surface on which the vehicle 1 travels via the unsprung mass, and a second control amount A2 that generates a damping force in the shock absorber 5 according to steering stability control that dampens vibrations of the sprung mass caused by changes in the behavior of the sprung mass according to the driving state of the vehicle 1, by comparing the magnitudes of each of the first control amount A1 and the second control amount A2, and determining which of the first control amount A1 and the second control amount A2 is larger, and the damping force control unit 14 generates a damping force in the shock absorber 5 based on the first control amount A1 or the second control amount A2 which is determined to be larger by the mediation unit 13.

[0055] In this case, the suspension ECU 10 has a modification unit 124 that can change the magnitude of the second control amount A2 relative to the magnitude of the first control amount A1.

[0056] In this case, the modification unit 124 changes the size of the second control variable A2 so that it is smaller than the first control variable A1 when ride comfort control is prioritized, and changes the size of the second control variable A2 so that it is larger than the first control variable A1 when steering stability control is prioritized.

[0057] In this case, the system has a determination unit 111 that determines whether or not a second vibration state C2, which is a predetermined vibration state, has occurred in the vibration state of the sprung mass member. The modification unit 124, if the determination unit 111 determines that the second vibration state C2 has occurred, changes the magnitude of the second control amount A2 so that it is smaller than the first control amount A1, regardless of the priority of ride comfort control and steering stability control. If the determination unit 111 determines that the second vibration state C2 has not occurred, it changes the magnitude of the second control amount A2 according to the preferred ride comfort control or steering stability control. In this case, the second vibration state C2 is a state in which the sprung mass member is vibrating due to the medium frequency component and the high frequency component among the frequency components that represent the vibration state.

[0058] According to these measurements, the suspension ECU 10 compares the magnitude of the first control variable A1 used by the arbitration unit 13 in ride comfort control with the magnitude of the second control variable A2 used in steering stability control, and outputs the first control variable A1 or the second control variable A2 that is determined to be larger to the damping force control unit 14. This allows the suspension ECU 10 to transition quickly and seamlessly between ride comfort control and steering stability control.

[0059] Furthermore, the suspension ECU 10 has a modification unit 124 that can change the magnitude of the second control amount A2. As a result, the arbitration unit 13 can compare the magnitude of the changed second control amount A2 with the magnitude of the first control amount A1, and as a result can quickly and accurately determine whether to prioritize ride comfort control or handling stability control and arbitrate accordingly.

[0060] In particular, if the determination unit 111 determines that a second vibration state C2 is occurring in the sprung mass of the vehicle 1, the modification unit 124 changes the magnitude of the second control amount A2 to be smaller than the magnitude of the first control amount A1, even if, for example, ride comfort control and steering stability control are required simultaneously, and the arbitration unit 13 outputs the first control amount A1 to the damping force control unit 14. As a result, in a situation where the second vibration state C2 occurs and ride comfort deteriorates, the damping force control unit 14 generates a damping force on the shock absorber 5 based on the first control amount A1, and as a result, the medium-frequency and high-frequency vibrations of the sprung mass can be dampened in accordance with the ride comfort control.

[0061] Next, a modified version of the above-described embodiment will be explained. First, in the first modified version, the determination unit 111 of the ride comfort control unit 11 can be omitted. In this case, when the sprung mass member is vibrating due to medium and high frequency vibrations, as in the second vibration state C2, the ride comfort control unit 11 outputs a first control amount A1 that is larger than the second control amount A2, which has been modified by the modification unit 124 to be larger by an increase amount B1, for example, by increasing the magnitude of the base control amount A12. That is, in this case, the ride comfort control unit 11 can relatively change the magnitude of the second control amount A2 with respect to the magnitude of the first control amount A1, and can perform its function as a "modification unit". As a result, the arbitration unit 13 can output a first control amount A1 that is larger than the second control amount A2 to the damping force control unit 14.

[0062] Furthermore, in the second modified configuration, one of the steering control unit 121 and the anti-pitch control unit 122 of the steering stability control unit 12 can be omitted, and the maximum value determination unit 123 can also be omitted. In this case, the modification unit 124 outputs a second control amount A2 to the damping force control unit 14, which is obtained by increasing or decreasing the control amount A211 output from the steering control unit 121 or the control amount A212 output from the anti-pitch control unit 122.

[0063] Furthermore, the suspension ECU 10, which is a vehicle suspension control device, is a computer. Therefore, it can be said that the computer is configured to perform the functions (or processes) of the ride comfort control unit 11, determination unit 111, handling stability control unit 12, steering control unit 121, anti-pitch control unit 122, maximum value determination unit 123, modification unit 124, mediation unit 13, and damping force control unit 14 described above. [Explanation of Symbols]

[0064] 1...Vehicle, 2...Wheel, 3...Suspension system, 4...Coil spring, 5...Shock absorber, 52...Linear solenoid unit, 567...Motor, 6...Steering system, 7...Brake ECU, 8...Sensor group, 81...Sprung mass acceleration sensor, 82...Steering angle sensor, 83...Motor rotation angle sensor, 84...Vehicle speed sensor, 10...Suspension ECU (Vehicle suspension control device), 11...Ride comfort control unit, 111...Determination unit, 12...Handling stability control unit, 121...Steering control unit, 122...Anti-pitch control unit, 123...Maximum value determination unit, 124...Modification unit, 13...Adjustment unit, 14...Damping force control unit, Gz...Vertical acceleration, δ...Steering angle, θ...Motor rotation angle, V...Vehicle speed, A1...First control variable, A2...Second control variable, A21...Control variable, F...Vibration information, C1...First vibration state, C2...Second vibration state (predetermined vibration state)

Claims

1. A shock absorber constituting a suspension system that is arranged corresponding to each wheel and connects the unsprung and sprung members of a vehicle includes a damping force control unit that generates a damping force that can be changed to dampen vibrations generated in the sprung member, A mediation unit that determines which of the first and second control amounts is larger by comparing the magnitudes of a first control amount, which generates the damping force on the shock absorber in accordance with ride comfort control that dampens vibrations of the upper sprung member caused by irregularities in the road surface on which the vehicle travels, input via the unsprung member; and a second control amount, which generates the damping force on the shock absorber in accordance with steering stability control that dampens vibrations of the upper sprung member caused by changes in the behavior of the upper sprung member according to the driving state of the vehicle; A modification unit that can change the magnitude of the second control variable relative to the magnitude of the first control variable, A determination unit that determines whether or not a predetermined vibration state occurs in the vibration state of the spring member, Equipped with, The damping force control unit, Based on the first control amount or the second control amount determined to be large by the arbitration unit, the damping force is generated in the shock absorber. The aforementioned modified part is, When the ride comfort control is prioritized, the size of the second control variable is changed so that it is smaller than the size of the first control variable. When the aforementioned steering stability control is prioritized, the magnitude of the second control variable is changed so that it is larger than the magnitude of the first control variable. The aforementioned modified part is, If the determination unit determines that the predetermined vibration state has occurred, regardless of the priority given to the ride comfort control and the steering stability control, the magnitude of the second control variable is changed so that the magnitude of the second control variable is smaller than the magnitude of the first control variable. If the determination unit determines that the predetermined vibration state has not occurred, the magnitude of the second control amount is changed according to the preferred ride comfort control or steering stability control. Vehicle suspension control device.

2. The predetermined vibration state is The vehicle suspension control device according to claim 1, wherein the sprung member is vibrating due to the medium-frequency component and the high-frequency component among the frequency components representing the vibration state.

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