Shock absorber control device

Abstract

A shock absorber control device capable of suppressing deterioration of ride quality is provided. The shock absorber control device (1) controls a front shock absorber (DF) provided on a front wheel (WF) and a rear shock absorber (DR) provided on a rear wheel (WR), and comprises: a preview sensor (11) for detecting a road surface condition in front of a vehicle (C); a steering angle sensor (12) for detecting a steering angle of the vehicle (C); and a control device (100) for controlling the front shock absorber (DF) and the rear shock absorber (DR) based on a detection value of the preview sensor (11). When the steering angle sensor (12) detects a steering angle exceeding a predetermined steering angle threshold, the control device (100) suppresses control of the rear shock absorber (DR) on the rear wheel (WR) side based on the detection value of the preview sensor (11).

Description

Technical Field

[0001] The present invention relates to a shock absorber control device. Background Art

[0002] Patent Document 1 describes a technique for controlling a shock absorber of a vehicle based on a detection value obtained from a sensor that detects the state of a road surface ahead of the vehicle.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-205196 Summary of the Invention

[0006] However, the technology described in Patent Document 1 assumes that the rear wheels follow the same trajectory as the front wheels because sensors are only located at the front of the vehicle. Therefore, if the driver steers the vehicle at a predetermined steering angle or above, the rear wheels' trajectories diverge from the front wheels'. Therefore, controlling the shock absorbers to match the front wheels could lead to a deterioration in ride quality.

[0007] An object of the present invention is to solve the above-mentioned conventional problems and to provide a damper control device capable of suppressing deterioration of riding comfort.

[0008] The present invention is a shock absorber control device for controlling a front shock absorber that makes the damping force of the front wheels variable and a rear shock absorber that makes the damping force of the rear wheels variable, and is characterized in that it comprises: a road surface condition detection mechanism that detects the road surface condition in front of the vehicle; a vehicle turning degree detection mechanism that detects the turning degree of the above-mentioned vehicle; and a control unit that controls the above-mentioned front shock absorber provided on the above-mentioned front wheel and the above-mentioned rear shock absorber provided on the above-mentioned rear wheel based on the detection value of the above-mentioned road surface condition detection mechanism, and the above-mentioned control unit suppresses the control of the above-mentioned rear shock absorber based on the detection value of the above-mentioned road surface condition detection mechanism when the above-mentioned vehicle turning degree detection mechanism detects a turning degree exceeding a prescribed turning degree threshold.

[0009] Effects of the Invention

[0010] According to the present invention, it is possible to provide a damper control device capable of suppressing deterioration of riding comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 1 is a diagram showing the overall configuration of a vehicle equipped with the damper control device according to the present embodiment.

[0012] Figure 2 1 is a diagram showing the configuration of a vehicle equipped with the damper control device according to the present embodiment.

[0013] Figure 3 This is a schematic diagram showing the travel trajectories of the front and rear wheels when the steering angle is equal to or less than a predetermined steering angle threshold.

[0014] Figure 4 This is a schematic diagram showing the travel trajectories of the front and rear wheels when the steering angle exceeds a predetermined steering angle threshold.

[0015] Figure 5 This is a graph showing the relationship between steering angle and vehicle speed.

[0016] Figure 6 This is a flowchart showing the operation of the damper control device according to the present embodiment.

[0017] Description of Reference Numerals

[0018] 1 Shock absorber control device

[0019] 11 Preview sensor (road surface condition detection mechanism)

[0020] 12 Steering angle sensor (vehicle turning degree detection mechanism)

[0021] 13 Steering torque sensor (vehicle turning degree detection mechanism)

[0022] 14 Yaw rate sensor (vehicle turning degree detection mechanism)

[0023] 15 Vehicle speed sensor (vehicle speed detection mechanism, slip detection mechanism)

[0024] 16 Wheel speed sensor (slip detection mechanism)

[0025] 100 Control device (control unit)

[0026] C Vehicle

[0027] DF front shock absorber (shock absorber)

[0028] DR rear shock absorber (shock absorber)

[0029] Vc vehicle speed

[0030] W wheel

[0031] WF front wheel

[0032] WR rear wheel

[0033] θ Rudder angle (turning degree) DETAILED DESCRIPTION

[0034] A shock absorber control device according to an embodiment of the present invention will be described in detail below with appropriate reference to the accompanying drawings. In the following description, the vehicle's forward direction is defined as "front," the reverse direction is defined as "rear," the vertically upward direction is defined as "up," the vertically downward direction is defined as "down," and the vehicle width directions are defined as "left" and "right."

[0035] Figure 1 1 is a diagram showing the overall configuration of a vehicle equipped with the damper control device according to the present embodiment.

[0036] like Figure 1 As shown, the shock absorber control device 1 of this embodiment is mounted on a vehicle C. The vehicle C is a four-wheeled vehicle equipped with an internal combustion engine (not shown) and four wheels W, namely, front wheels WF, WF, and rear wheels WR, WR. The front wheels WF are steered wheels. Furthermore, the vehicle C is equipped with an electric power steering system (EPS). This electric power steering system is a well-known device that assists the driver by reducing the steering force required to steer the front wheels WF by driving an electric motor 3.

[0037] In addition, each front wheel WF of the vehicle C is provided with a front shock absorber DF (shock absorber) and a spring SF (see Figure 2 ) and other suspensions. In addition, each rear wheel WR of the vehicle C is provided with a rear shock absorber DR (shock absorber) and a spring SR (see Figure 2 ) and other suspensions. The front shock absorber DF and rear shock absorber DR are composed of known variable damping force shock absorbers capable of arbitrarily changing the damping force. Furthermore, the shock absorbers applicable to this embodiment are not limited to variable damping force shock absorbers and can also be applied to active suspensions.

[0038] In addition, the vehicle C has a device for detecting the road surface R in front of the vehicle (in front of the vehicle C) (see Figure 2 ) state preview sensors (Preview sensor) (road surface state detection means) 11, 11, and a control device (control unit) 100 that controls the front shock absorber DF and the rear shock absorber DR based on the detection value of the preview sensor 11.

[0039] In addition, vehicle C is equipped with: a steering angle sensor 12 (vehicle turning degree detection mechanism), a steering torque sensor 13 (vehicle turning degree detection mechanism), a yaw rate sensor 14 (vehicle turning degree detection mechanism), a vehicle speed sensor 15 (vehicle speed detection mechanism, slip detection mechanism), and a wheel speed sensor 16 (slip detection mechanism).

[0040] The steering angle sensor 12 detects the steering angle θ (rotation angle, reference Figure 5The steering angle sensor 12 detects the steering angle θ (rotation angle) of the steering device (steering wheel) H using, for example, an angle sensor that measures the rotation angle of the motor 3 .

[0041] Steering torque sensor 13 (at Figure 1 The steering torque sensor 13 (referred to as a "torque sensor" in the figure) detects the steering torque (manual steering force) input by the driver via the steering device H. The steering torque sensor 13 can be used as a vehicle turning degree detection means in place of the above-mentioned steering angle sensor 12.

[0042] The yaw rate sensor 14 detects the yaw rate (turning angular velocity) of the vehicle C. The yaw rate sensor 14 can be used as a vehicle turning degree detection unit in place of the steering angle sensor 12 and the steering torque sensor 13 .

[0043] The vehicle speed sensor 15 detects the traveling speed of the vehicle C (hereinafter referred to as vehicle speed Vc).

[0044] The wheel speed sensor 16 detects the rotation speed of the wheel W as a wheel speed pulse signal. Figure 1 , although it is described that the wheel speed sensor 16 is provided on only one wheel W, in reality, the wheel speed sensors 16 are provided on both the front wheels WF, WF and the rear wheels WR, WR.

[0045] The control device 100 controls the shock absorbers of the front wheels WF and rear wheels WR and is comprised of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), various interfaces, and circuits. Shock absorber control controls the front and rear shock absorbers DF and DR to mitigate or absorb vibrations of the vehicle body relative to the road surface R, thereby improving the ride quality of the vehicle C.

[0046] In addition, the control device 100 is connected to the preview sensor 11, the steering angle sensor 12, the steering torque sensor 13, the yaw rate sensor 14, the vehicle speed sensor 15, and the wheel speed sensor 16 to obtain various information such as the road surface state, the steering angle θ, the steering torque, the yaw rate, the vehicle speed Vc, and the wheel speed. Figure 1 In the embodiment, the control device 100 and the sensors 11 to 16 are connected to each other via a communication medium such as CAN (Control Area Network).

[0047] Figure 2 1 is a diagram showing the configuration of a vehicle equipped with the damper control device according to the present embodiment.

[0048] like Figure 2 As shown, the preview sensor 11 detects the condition of the road surface R (road surface condition) in front of the vehicle C. The preview sensor 11 is provided on the frame member F that constitutes the front portion of the vehicle C. Furthermore, the preview sensor 11 is located forward of the front wheels WF of the frame member F. In this embodiment, the preview sensor 11 is provided forward of the front wheels WF and not on the rear wheel WR side. The preview sensor 11 is provided on each of the left and right front wheels WF.

[0049] The preview sensor 11 is configured to detect the state of the road surface R immediately in front of the front wheel WF, as indicated by the white arrow. The preview sensor 11 can be appropriately selected from a range of sensors, such as radar, camera, and laser. The preview sensor 11 is not limited to a single sensor; a combination of multiple sensor types, such as camera and laser, may also be used.

[0050] Figure 3 This is a schematic diagram showing the travel trajectories of the front and rear wheels when the steering angle is equal to or less than a predetermined steering angle threshold.

[0051] like Figure 3 As shown, when the steering device H is operated to turn the vehicle C rightward at a steering angle θ that is less than or equal to a predetermined steering angle threshold, the front wheel WF moves along an arcuate planned travel line (travel trajectory) LF1 based on the turning center O1. Furthermore, the rear wheel WR moves along an arcuate planned travel line (travel trajectory) LR1 based on the turning center O1. Thus, with respect to the vehicle C, the planned travel line LR1 of the rear wheel WR crosses the planned travel line LF1 of the front wheel WF on the inner side (toward the turning center O1) due to the inner wheel difference.

[0052] The preview sensor 11 detects the road surface condition ahead of the front wheels WF (ahead of the vehicle), for example, by having a predetermined measurement range (prescribed range) S1 in the left-right direction (width direction). Furthermore, the predetermined measurement range S1 is set so that the planned travel line LF1 and the predetermined measurement range S1 overlap even when the steering angle θ (turning angle) of the front wheels WF is maximized. This allows detection of road surface conditions regardless of the steering angle θ of the front wheels WF.

[0053] Furthermore, when the steering angle θ is below a predetermined steering angle threshold, both the front wheel WF and the rear wheel WR pass through the predetermined measurement range S1. Specifically, the predetermined steering angle threshold is the maximum steering angle at which a difference is created between the (curvature) radius of the running trajectory of the front wheel WF and the running trajectory of the rear wheel WR, and at which the running trajectory of the rear wheel WR falls within the measurement range of the preview sensor 11. Therefore, the front shock absorber DF provided on the front wheel WF and the rear shock absorber DR provided on the rear wheel WR are controlled based on the detection values detected by the preview sensor 11. In other words, the front shock absorber DF and the rear shock absorber DR are controlled by the control device 100 to appropriately suppress vehicle body vibration.

[0054] Figure 4 This is a schematic diagram showing the travel trajectories of the front and rear wheels when the steering angle exceeds a predetermined steering angle threshold.

[0055] like Figure 4 As shown, when the steering device H is operated to turn the vehicle C rightward at a steering angle θ exceeding a predetermined steering angle threshold, the front wheel WF moves along an arcuate planned travel line (travel trajectory) LF2 based on the turning center O2. Furthermore, the rear wheel WR moves along an arcuate planned travel line (travel trajectory) LR2 based on the turning center O2. Thus, with respect to the vehicle C, the rear wheel WR's planned travel line LR2 passes inside (toward the turning center O2) the front wheel WF's planned travel line LF2 due to the inner wheel differential.

[0056] Furthermore, if the steering angle θ exceeds a predetermined steering angle threshold, the front wheel WF passes through the measurement range S1, but the rear wheel WR passes outside of the measurement range S1. Consequently, if the rear shock absorber DR is controlled based on the detected road surface conditions, vehicle body vibration may increase, potentially degrading the ride quality. Therefore, in this embodiment, shock absorber control of the rear wheel WR (control of the rear shock absorber DR) is suppressed based on the steering angle θ.

[0057] Figure 5 This is a graph showing the relationship between vehicle speed and steering angle.

[0058] like Figure 5 As shown, the area indicated by the diagonal lines is the area where the shock absorber control of the rear wheel WR (control of the rear shock absorber DR) is performed based on the preview sensor 11. And, the thick line outlined in this area represents the relationship between the vehicle speed Vc (the driving speed of the vehicle C) and the prescribed steering angle threshold. That is, as the vehicle speed Vc (the driving speed of the vehicle C) becomes faster, the prescribed steering angle threshold becomes smaller, and the steering angle θ (steering wheel angle) that exceeds the prescribed steering angle threshold becomes smaller. In this way, when the vehicle speed Vc is high, the shock absorber control of the rear wheel WR (control of the rear shock absorber DR) is not applicable even when the steering angle θ is small. In addition, Figure 5In the embodiment, a maximum vehicle speed (Vmax) is set, and when the maximum vehicle speed is exceeded, the damper control of the rear wheel WR (control of the rear damper DR) based on the preview sensor 11 is not performed.

[0059] In addition, if Figure 5 As shown, when the vehicle speed Vc is negative (when the vehicle C is moving backward), control of the rear wheels WR (control of the rear shock absorber DR) using the preview sensor 11 is not applied. This is because the rear wheels WR are not provided with the preview sensor 11, and thus, shock absorber control using the preview sensor 11 cannot be performed. Furthermore, whether the vehicle C is moving backward can be determined by detecting the selected position of a shift lever (not shown) located on the driver's seat of the vehicle C, or by detecting rotation toward the negative side (reverse direction) using the wheel speed sensor 16.

[0060] Figure 6 This is a flowchart showing the operation of the damper control device according to the present embodiment.

[0061] First, when the start button (not shown) or ignition switch (not shown) of the vehicle C is turned on, the preview sensor 11 is activated to start detecting the road surface condition. Figure 6 As shown, in step S10, the control device 100 detects the vehicle speed Vc of the vehicle C and the steering angle θ of the steering device H. The steering angle θ of the steering device H is detected by the steering angle sensor 12. Alternatively, the steering angle θ may be detected by the steering torque sensor 13 or the yaw rate sensor 14.

[0062] In step S20, the control device 100 determines whether the steering angle θ detected by the steering angle sensor 12 exceeds a predetermined steering angle threshold. If the control device 100 determines that the steering angle θ exceeds the predetermined steering angle threshold (S20, Yes), the control device 100 proceeds to step S60. If the control device 100 determines that the steering angle θ is below the predetermined steering angle threshold (S20, No), the control device 100 proceeds to step S30. In addition, the steering angle θ exceeding the predetermined steering angle threshold refers to the steering angle θ exceeding the predetermined steering angle threshold. Figure 4 As described above, the steering angle when the rear wheel WR passes through a position that does not overlap with the measurement range S1 by the preview sensor 11.

[0063] In addition, the control device 100 refers to the vehicle speed Vc obtained in step S10. Figure 5 At this time, when the vehicle speed Vc is high, the predetermined steering angle threshold is changed to decrease, and when the vehicle speed Vc is low, the predetermined steering angle threshold is changed to increase.

[0064] In step S60, the control device 100 prohibits shock absorber control of the rear wheels WR. Specifically, shock absorber control (control of the rear shock absorber DR) based on the detection values of the preview sensor 11 is not performed on the rear wheels WR. Alternatively, rather than prohibiting shock absorber control of the rear wheels WR, shock absorber control of the rear wheels WR may be suppressed. Suppressing shock absorber control also includes situations where shock absorber control of the rear wheels WR is not prohibited (zeroed) but rather the control weight is changed, not completely set to zero, and where control based on the detection values of the preview sensor 11 is considered but not actually used in control.

[0065] In step S30, the control device 100 executes damper control. If damper control has already been executed, it continues. Specifically, damper control of the front wheels WF and rear wheels WR (control of the front dampers DF and control of the rear dampers DR) is executed based on the detection values of the preview sensor 11.

[0066] In step S40 , the control device 100 determines whether the vehicle C is moving backward. If the vehicle C is moving backward ( S40 , Yes), the process proceeds to step S60 . If the vehicle C is not moving backward ( S40 , No), the process proceeds to step S50 .

[0067] In step S50, the control device 100 determines whether the slip value of vehicle C is greater than a predetermined slip threshold. If the slip value of vehicle C is greater than the predetermined slip threshold (S50: Yes), the process proceeds to step S60. If the slip value of vehicle C is not greater than the predetermined slip threshold (S50: No), the process returns. The slip value is determined, for example, based on the slip ratio used in the ABS (Anti-lock Brake System) installed in vehicle C. A slip value greater than the predetermined slip threshold means that the slip value calculated based on vehicle speed Vc and wheel speed Vw is greater than the predetermined slip threshold, or that the ABS is activated.

[0068] As described above, the shock absorber control device 1 of the present embodiment controls the front shock absorber DF provided on the front wheel WF and the rear shock absorber DR provided on the rear wheel WR. The device 1 includes: a preview sensor 11 for detecting the road surface condition ahead of the vehicle C; a steering angle sensor 12 (steering torque sensor 13, yaw rate sensor 14) for detecting the steering angle θ (yaw rate) of the vehicle C; and a control device 100 for controlling the front shock absorber DF and the rear shock absorber DR based on the detection value of the preview sensor 11. When the steering angle sensor 12 detects a steering angle θ exceeding a predetermined steering angle threshold, the control device 100 suppresses control of the rear shock absorber DR on the rear wheel WR side based on the detection value of the preview sensor 11 (see FIG. 1 ). Figure 6Thus, when the steering angle θ exceeds the predetermined steering angle threshold, the rear wheel WR is likely to follow a different travel trajectory from the front wheel WF. Therefore, by suppressing the damper control of the rear wheel WR based on the preview sensor 11, it is possible to suppress deterioration of the ride quality.

[0069] In addition, the present embodiment includes a vehicle speed sensor 15 for detecting the vehicle speed Vc of the vehicle C. The control device 100 changes the predetermined steering angle threshold value (see FIG. 1 ) according to the vehicle speed Vc detected by the vehicle speed sensor 15. Figure 5 Thus, since the travel trajectory of the rear wheel WR (the planned travel lines LR1 and LR2) differs depending on the vehicle speed Vc, the ride comfort can be further suppressed from being deteriorated by changing the predetermined steering angle threshold value according to the vehicle speed Vc.

[0070] In the present embodiment, the control device 100 suppresses the control of the rear shock absorber DR on the rear wheel WR side based on the detection value of the preview sensor 11 when the vehicle C moves backward (see Figure 5 、 Figure 6 Thus, when the vehicle moves backward, the damper control of the rear wheels WR by the preview sensor 11 cannot be performed. Therefore, by suppressing the damper control of the rear wheels WR by the preview sensor 11, it is possible to suppress deterioration of the ride quality.

[0071] In addition, the present embodiment includes a vehicle speed sensor 15 and a wheel speed sensor 16 for detecting the slip degree of the wheel W. When the control device 100 detects that the front wheel WF and / or the rear wheel WR has a slip degree greater than a predetermined level at a steering angle θ less than or equal to a predetermined steering angle threshold, the control device 100 suppresses the damper control of the rear wheel WR based on the preview sensor 11 (see FIG. Figure 6 Thus, since the travel trajectory (planned travel lines LR1, LR2) may change if the wheel W slips, deterioration of the ride quality can be suppressed by suppressing the damper control of the rear wheel WR based on the preview sensor 11.

[0072] Furthermore, the present invention is not limited to the above-described embodiment and includes various modifications. For example, while this embodiment illustrates a vehicle C in which a steering angle is applied only to the front wheels WF, the present invention is also applicable to a vehicle employing a four-wheel steering system in which a steering angle is applied to all four wheels: the front wheels WF and the rear wheels WR.

[0073] In the above embodiment, the control device 100 is configured to determine whether the steering angle θ detected by the steering angle sensor 12 exceeds a predetermined steering angle threshold value (see Figure 6S20), in a modified example, it can also be configured to determine whether the steering angle θ is greater than a prescribed second steering angle threshold. In such a modified example, when the steering angle θ is less than the prescribed second steering angle threshold, both the front wheel WF and the rear wheel WR pass through the prescribed measurement range S1, and when the steering angle θ is greater than the prescribed second steering angle threshold, the front wheel WF passes through the measurement range S1, but the rear wheel WR passes from a position deviating from the measurement range S1. That is, the prescribed second steering angle threshold refers to the minimum steering angle at which a difference occurs between the (curvature) radius of the driving trajectory of the front wheel WF and the (curvature) radius of the driving trajectory of the rear wheel WR and the driving trajectory of the rear wheel WR is outside the measurement range of the preview sensor 11. In such a modified example, when the steering angle θ greater than the prescribed second steering angle threshold is detected by the steering angle sensor 12, the control device 100 suppresses the control of the rear shock absorber DR on the rear wheel WR side based on the detection value of the preview sensor 11 (refer to Figure 6 S60).

[0074] The preview sensor 11 detects the road surface condition in front of the front wheel WF (in front of the vehicle) and performs measurement so as to have a predetermined measurement range (predetermined range) S1 in a direction parallel to the axle of the front wheel, for example.

Claims

1. A shock absorber control device for controlling a front shock absorber that varies the damping force of a front wheel and a rear shock absorber that varies the damping force of a rear wheel, the shock absorber control device comprising: a road surface condition detecting mechanism for detecting the road surface condition ahead of the vehicle, the mechanism performing measurement so as to have a predetermined range in the width direction of the vehicle; a vehicle turning degree detecting mechanism for detecting a turning degree of the vehicle; a control unit for controlling the front shock absorber provided on the front wheel and the rear shock absorber provided on the rear wheel based on a detection value of the road surface state detection mechanism; and a slip detection mechanism for detecting a slip value of the vehicle, The control unit suppresses control of the rear shock absorber based on the detection value of the road surface state detection means when the vehicle turning degree detection means detects a turning degree exceeding a predetermined turning degree threshold value. The control unit, when the turning angle is less than or equal to the predetermined turning angle threshold, When a slip value of the front wheel and / or the rear wheel is detected to be greater than a predetermined slip threshold, the control of the rear shock absorber is suppressed; When slip values of the front wheels and the rear wheels are detected to be within a range smaller than the predetermined slip threshold value, the control of the rear shock absorber is not suppressed.

2. The shock absorber control device according to claim 1, wherein: A vehicle speed detection mechanism is provided for detecting the vehicle speed. The control unit changes the predetermined turning degree threshold value according to the vehicle speed detected by the vehicle speed detection means.

3. The shock absorber control device according to claim 1 or 2, characterized in that: The control portion suppresses the control of the rear shock absorber when the vehicle moves backward.

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