Electric suspension

Abstract

Provided is an electric suspension device that provides a comfortable ride with a sense of unity between the driver and the vehicle, even during braking in sporty driving situations. The electric suspension device includes: an electromagnetic actuator, disposed between the vehicle body and wheels, that generates a load to attenuate vehicle body vibrations; an information acquisition unit that acquires information about the vehicle's sprung load state and the road surface conditions; a target load calculation unit that calculates a first target load for skyhook control based on the sprung load state and a second target load for predictive control based on the road surface conditions; and a load control unit that performs load control on the electromagnetic actuator. The target load calculation unit further calculates a third target load for pitch generation control based on a target pitch angle and calculates a combined target load by combining the first and second target loads with the third target load. The load control unit uses the combined target load to control the load of the electromagnetic actuator.

Description

Technical Field

[0001] The present invention relates to an electric suspension device including an actuator, wherein the actuator is provided between a vehicle body and wheels and generates a load for attenuating vibration of the vehicle body. Background Art

[0002] Conventionally, there is known an electric suspension device including an actuator provided between a vehicle body and wheels for generating a load for damping vibrations of the vehicle body (see, for example, Patent Document 1).

[0003] The electric suspension device disclosed in Patent Document 1 includes a control device that controls a control object capable of controlling the output of a system that outputs a response to a disturbance input with a time delay. The control device generates a control command for eliminating the influence of the disturbance from the output based on a transfer function from the disturbance input to the system output, a transfer function from a control command for the control object output by the control system to the output, and disturbance information input to the system.

[0004] According to the electric suspension device of Patent Document 1, the control device operates so as to cancel the vibration of the vehicle body generated by the road surface input, and thus the vibration of the vehicle body can be suppressed.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-134899 Summary of the Invention

[0006] Furthermore, for example, when a front-wheel drive vehicle is engaged in sport driving, there is a demand to flexibly switch the vehicle's direction of travel by utilizing a tuck-in phenomenon associated with the pitching behavior generated when the vehicle brakes.

[0007] However, in the electric suspension device of Patent Document 1, the control device inherently operates to suppress the pitching (dive) behavior that occurs when the vehicle brakes, regardless of whether the vehicle is in sporty driving. Consequently, when braking in a front-wheel drive vehicle during sporty driving, the vehicle's direction of travel cannot be sensitively switched by utilizing the entrainment phenomenon. Consequently, the sense of unity between the driver and the vehicle during sporty driving is compromised, potentially causing the driver to experience a sense of discomfort.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electric suspension device that can provide a comfortable ride with a sense of unity between the driver and the vehicle even during braking in a sporty driving situation.

[0009] In order to achieve the above-mentioned object, the electric suspension device of the present invention (1) comprises: an actuator, which is provided between a vehicle body and a wheel, and generates a load for attenuating the vibration of the vehicle body; an information acquisition unit, which acquires information on the sprung state quantity and the state of the road surface on which the vehicle is traveling; and a target load calculation unit, which calculates a target load related to skyhook control based on the sprung state quantity. control), and calculates a second target load involving predictive control based on the above-mentioned driving road surface state; and a load control unit, which uses the calculation result of the above-mentioned target load calculation unit to perform load control on the above-mentioned actuator, the most important feature of the above-mentioned electric suspension device is that the above-mentioned information acquisition unit further obtains information related to the front and rear acceleration and deceleration of the vehicle, and is also provided with a target pitch angle derivation unit that derives the target pitch angle of the vehicle based on the information related to the above-mentioned front and rear acceleration and deceleration, the above-mentioned target load calculation unit further calculates a third target load involving pitch generation control based on the target pitch angle derived by the above-mentioned target pitch angle derivation unit, and calculates a combined target load that combines the above-mentioned first target load, the second target load and the above-mentioned third target load, and the above-mentioned load control unit uses the above-mentioned combined target load to perform load control on the above-mentioned actuator.

[0010] Effects of the Invention

[0011] According to the present invention, a comfortable ride accompanied by a sense of unity between the driver and the vehicle can be achieved even during braking in a sporty driving situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a diagram showing the overall configuration of an electric suspension device according to an embodiment of the present invention.

[0013] Figure 2 It is a partial cross-sectional view of an electromagnetic actuator included in the electric suspension device according to the embodiment of the present invention.

[0014] Figure 3 It is a structural diagram of the interior and peripheral parts of a load control ECU included in the electric suspension device according to the embodiment of the present invention.

[0015] Figure 4 This is a diagram conceptually showing the internal structure of a load control ECU included in the electric suspension device according to the embodiment of the present invention.

[0016] Figure 5A These are diagrams for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0017] Figure 5B These are diagrams for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0018] Figure 6This is a flowchart for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0019] Description of Reference Numerals

[0020] 10 vehicles

[0021] 11 Electric suspension

[0022] 13 Electromagnetic actuator (actuator)

[0023] 41 Information Acquisition Department

[0024] 43 Target load calculation unit

[0025] 45 Load Control Unit

[0026] 61 Target pitch angle derivation unit

[0027] 63 Vehicle Status Estimation Unit (Information Acquisition Unit)

[0028] 65 First subtraction unit (sprung state quantity correction unit)

[0029] 71 First target load calculation unit (target load calculation unit)

[0030] 73 Second target load calculation unit (target load calculation unit)

[0031] 75 3rd target load calculation unit (target load calculation unit)

[0032] 77 Merging Unit (Target Load Calculation Unit)

[0033] θ p Target pitch angle DETAILED DESCRIPTION

[0034] Hereinafter, the electric suspension device 11 according to the embodiment of the present invention will be described in detail with reference to the drawings as appropriate.

[0035] In addition, in the drawings shown below, components having common functions are marked with common reference numerals. In this case, as a principle, repeated descriptions are omitted. In addition, for the convenience of description, there are cases where the size and shape of components are deformed or exaggerated and schematically represented.

[0036] [Basic Structure Common to the Electric Suspension Devices 11 According to the Embodiments of the Present Invention]

[0037] First, refer to Figure 1 、 Figure 2 A basic structure common to the electric suspension device 11 according to the embodiment of the present invention will be described.

[0038] Figure 1This is a diagram showing an overall configuration common to the electric suspension device 11 according to the embodiment of the present invention. Figure 2 It is a partial cross-sectional view of the electromagnetic actuator 13 constituting a part of the electric suspension device 11 .

[0039] like Figure 1 As shown, the electric suspension device 11 according to the embodiment of the present invention is configured to include a plurality of electromagnetic actuators 13 provided for each wheel of a vehicle (sometimes referred to as the subject vehicle) 10, and a load control ECU 15. The plurality of electromagnetic actuators 13 and the load control ECU 15 are connected via power supply lines 14 (see FIG. Figure 1 solid line) and signal line 16 (see Figure 1 The power supply line 14 is used to supply load control power from the load control ECU 15 to the plurality of electromagnetic actuators 13, and the signal line 16 is used to send the electric motor 31 (refer to Figure 2 ) load control signal.

[0040] In this embodiment, four electromagnetic actuators 13 are provided for each wheel, including the front wheels (left front wheel and right front wheel) and the rear wheels (left rear wheel and right rear wheel). The electromagnetic actuators 13 provided for each wheel are independently load-controlled according to the extension and contraction operation of each wheel.

[0041] In the embodiment of the present invention, unless otherwise specified, the plurality of electromagnetic actuators 13 have a common structure. Therefore, the structure of one electromagnetic actuator 13 will be described instead of describing the plurality of electromagnetic actuators 13 .

[0042] like Figure 2 As shown, the electromagnetic actuator 13 includes a base housing 17 , an outer tube 19 , a ball bearing 21 , a ball screw shaft 23 , a plurality of balls 25 , a nut 27 , and an inner tube 29 .

[0043] The base housing 17 rotatably supports the base end of the ball screw shaft 23 via a ball bearing 21. The outer tube 19 is provided on the base housing 17 and houses the ball screw mechanism 18, which includes the ball screw shaft 23, a plurality of balls 25, and a nut 27. The balls 25 roll along the screw grooves of the ball screw shaft 23. The nut 27 engages with the ball screw shaft 23 via the balls 25, converting the rotational motion of the ball screw shaft 23 into linear motion. The inner tube 29, connected to the nut 27, is integral with the nut 27 and displaces axially along the outer tube 19.

[0044] In order to transmit the rotational driving force to the ball screw shaft 23, as shown in FIG. Figure 2As shown, the electromagnetic actuator 13 includes an electric motor 31, a pair of pulleys 33, and a belt member 35. The electric motor 31 is provided in parallel with the outer tube 19 in the base housing 17. The pulleys 33 are attached to the motor shaft 31a of the electric motor 31 and the ball screw shaft 23, respectively. The belt member 35 is suspended from the pair of pulleys 33 to transmit the rotational driving force of the electric motor 31 to the ball screw shaft 23.

[0045] The electric motor 31 is provided with a resolver 37 that detects a rotation angle signal of the electric motor 31. The rotation angle signal of the electric motor 31 detected by the resolver 37 is transmitted to the load control ECU 15 via a signal line 16. The electric motor 31 is rotationally controlled based on the load control power supplied by the load control ECU 15 to each of the plurality of electromagnetic actuators 13 via a power supply line 14.

[0046] In addition, in this embodiment, if Figure 2 As shown, by adopting a layout in which the motor shaft 31a of the electric motor 31 and the ball screw shaft 23 are arranged substantially parallel to each other and connected to each other, the axial dimension of the electromagnetic actuator 13 is shortened. However, a layout in which the motor shaft 31a of the electric motor 31 and the ball screw shaft 23 are arranged coaxially and connected to each other may also be adopted.

[0047] In the electromagnetic actuator 13 of the embodiment of the present invention, as Figure 2 As shown, a connecting portion 39 is provided at the lower end of the base shell 17. The connecting portion 39 is connected and fixed to the unsprung member 81 (lower arm, steering knuckle, etc. on the wheel side, see Figure 5A On the other hand, the upper end portion 29a of the inner tube 29 is connected and fixed to the sprung member 83 (the strut tower portion on the vehicle body side, etc., see Figure 5A ).

[0048] In short, the electromagnetic actuator 13 and the spring member (suspension) 85 (see FIG. 1 ) provided between the sprung member (vehicle body) 83 and the unsprung member (wheels etc. with tires mounted thereon, hereinafter collectively referred to as "wheels etc.") 81 of the vehicle 10. Figure 5A ) are arranged in parallel. The electromagnetic actuator 13 acts as a virtual shock absorber 87 (see Figure 5A )’s role.

[0049] The unsprung members (wheels, etc.) 81 provided for the left and right wheels are connected to each other via a stabilizer (not shown).

[0050] A spring component 91 and a damper component 93 are interposed between an unsprung member (wheel, etc.) 81 of the vehicle 10 and the road surface. In short, the tire mounted on the wheel of the vehicle 10 functions as the spring component 91 and the damper component 93.

[0051] The electromagnetic actuator 13 constructed as described above operates as follows. For example, consider a situation where a driving force causing an upward vibration is input to the connecting portion 39 from the wheel side of the vehicle 10. In this situation, the inner tube 29 and the nut 27 tend to descend integrally relative to the outer tube 19 to which the driving force causing an upward vibration is applied. As a result, the ball screw shaft 23 tends to rotate in a direction that conforms to the descent of the nut 27. At this time, a rotational driving force from the electric motor 31 is generated in a direction that obstructs the descent of the nut 27. The rotational driving force of the electric motor 31 is transmitted to the ball screw shaft 23 via the belt component 35.

[0052] In this manner, the electromagnetic actuator 13 damps the vibration that is transmitted from the wheel side to the vehicle body side by causing a reaction force (damping force) to act on the ball screw shaft 23 against the driving force associated with the upward vibration.

[0053] [Internal Structure of Load Control ECU 15]

[0054] Next, refer to Figure 3 The configuration of the interior and peripheral portions of the load control ECU 15 included in the electric suspension device 11 according to the embodiment of the present invention will be described.

[0055] Figure 3 It is a structural diagram of the interior and peripheral parts of the load control ECU 15 included in the electric suspension device 11 according to the embodiment of the present invention.

[0056] [Electric Suspension Device 11 According to an Embodiment of the Present Invention]

[0057] The load control ECU 15 included in the electric suspension device 11 according to the embodiment of the present invention is configured to include a microcomputer that performs various computational processing. The load control ECU 15 has a load control function. Based on the rotation angle signal including the stroke position of the electric motor 31 detected by the resolver 37, the combined target load (described in detail later), the motor current applied to the electric motor 31, and other information, it controls the loads of each of the multiple electromagnetic actuators 13. This generates loads related to the attenuation and extension / retraction operations of the electromagnetic actuators 13.

[0058] In order to achieve such load control functions, such as Figure 3 As shown, the load control ECU 15 includes an information acquisition unit 41 , a target load calculation unit 43 , and a load control unit 45 .

[0059] like Figure 3As shown, the information acquisition unit 41 acquires the timing information of the acceleration operation amount and the brake operation amount. The information of the acceleration operation amount can be acquired by the acceleration sensor 51 that detects the amount of depression of the accelerator pedal (not shown) provided by the vehicle 10. The information of the brake operation amount can be acquired by the brake sensor 53 that detects the amount of depression of the brake pedal (not shown) provided by the vehicle 10. In addition, the information of the brake operation amount can be replaced by or based on the information of the brake hydraulic pressure acting on the brake system. In this case, the information of the brake hydraulic pressure can be acquired by the hydraulic pressure sensor (not shown) that detects the brake hydraulic pressure acting on the brake system.

[0060] Furthermore, the information acquisition unit 41 acquires a preview image and vehicle height information as time-series information regarding the road surface conditions in the direction of travel of the vehicle 10. The preview image information can be acquired, for example, by using a camera 42 mounted on the vehicle 10 or by using external sensors such as radar or lidar. Furthermore, the vehicle height information can be acquired, for example, by using a vehicle height sensor 55 that detects the height of the vehicle 10.

[0061] The information acquisition unit 41 acquires time series information on each of the sprung acceleration and the unsprung acceleration. The sprung acceleration information can be acquired based on the detection values of the sprung acceleration sensor 57 provided on the sprung member (vehicle body) 83 of the vehicle 10. Furthermore, the unsprung acceleration information can be acquired based on the detection values of the unsprung acceleration sensor 59 provided on the unsprung member (wheel, etc.) 81 of the vehicle 10.

[0062] The information acquired by the information acquisition unit 41 , including the accelerator operation amount, brake operation amount, preview image, vehicle height, sprung acceleration, unsprung acceleration, stroke position of the electromagnetic actuator 13 , and motor current of the electric motor 31 , is sent to the target load calculation unit 43 .

[0063] like Figure 3 As shown, the target load calculation unit 43 has a function of calculating, based on the various information obtained by the information acquisition unit 41 , a target value related to the damping operation and the extension and contraction operation of the electromagnetic actuator 13 , that is, a combined target load.

[0064] In practice, the target load calculation unit 43 includes a first target load calculation unit 71 for calculating a first target load related to skyhook control, a second target load calculation unit 73 for calculating a second target load related to look-ahead control, and a third target load calculation unit 75 for calculating a third target load related to pitch generation control. The structures of the first target load calculation unit 71, the second target load calculation unit 73, and the third target load calculation unit 75 will be described in detail later.

[0065] The load control unit 45 calculates a target current value that can achieve the combined target load determined by the target load calculation unit 43. The load control unit 45 then controls the drive of the electric motors 31 included in each of the plurality of electromagnetic actuators 13 so that the motor current of the electric motors 31 follows the calculated target current value. Load control of each electric motor 31 is performed independently in each of the plurality of electromagnetic actuators 13.

[0066] [Main Configuration of the Load Control ECU 15 Included in the Electric Suspension Device 11]

[0067] Next, refer to Figure 4 、 Figure 5A 、 Figure 5B The internal structure of the load control ECU 15 included in the electric suspension device 11 according to the embodiment of the present invention will be described.

[0068] Figure 4 This is a diagram conceptually showing the internal structure of the load control ECU 15 included in the electric suspension device 11 according to the embodiment of the present invention. Figure 5A 、 Figure 5B It is a diagram for explaining the operation of the electric suspension device 11 .

[0069] like Figure 4 As shown, the load control ECU 15 included in the electric suspension device 11 includes a target pitch angle derivation unit 61, a vehicle state estimation unit 63, a first subtraction unit 65, a second subtraction unit 67, a first target load calculation unit 71, a second target load calculation unit 73, a third target load calculation unit 75, and a merging unit 77. The vehicle state estimation unit 63 also functions as the information acquisition unit 41. The first target load calculation unit 71, the second target load calculation unit 73, and the third target load calculation unit 75 are included in the target load calculation unit 43.

[0070] The target pitch angle derivation unit 61 includes a longitudinal acceleration calculation unit 68 and a target pitch angle calculation unit 69 .

[0071] Here, if Figure 5A As shown, the target pitch angle in the target pitch angle derivation unit 61 is derived using a motion equation involving pitching motion (refer to equation (1)) including an attenuation coefficient Cs of a virtual shock absorber 87 possessed by the electromagnetic actuator 13 respectively provided on the four wheels of the vehicle 10 (wherein the attenuation coefficient set for each virtual shock absorber 87 is made common for the sake of convenience).

[0072] [Formula 1]

[0073]

[0074] In formula (1), Jp represents the pitching inertia moment of the sprung member (vehicle body) 83, M b represents the mass of the vehicle body 83, W b represents half the length of the wheelbase of the vehicle 10, K s represents the spring constant of the spring member (suspension) 85 (the spring constant of the suspension of the four wheels is set to a common value), θ p represents the pitch angle (θ p ” represents the pitch angular acceleration of the vehicle body 83), z represents the front-to-back displacement of the vehicle body 83 (z” represents the front-to-back acceleration of the vehicle body 83), h represents the distance from the pitch center to the center of gravity of the vehicle body 83, and x t (x tf Indicates the front side, x tr represents the rear side, and the same applies hereinafter) represents the vertical displacement (unsprung displacement) of the unsprung member (wheel, etc.) 81, and x b (x bf , x br ) represents the vertical displacement of the vehicle body 83 (vehicle body displacement).

[0075] In addition, Figure 5A In, M t represents the mass of the wheel, etc., x r (x rf , x rr ) represents the road height input, K t represents the spring constant of the unsprung member (tire) 81 (the spring constant of the tires of the four wheels is set to a common value), C t represents the damping coefficient of the unsprung member (tire) 81 (the damping coefficients of the tires of the four wheels are set to a common value), F f represents the thrust (load) of the front electromagnetic actuator 13, F r represents the thrust (load) of the rear electromagnetic actuator 13 .

[0076] Here, if the front side of the vehicle body is displaced (x bf ), vehicle front speed (x' bf ), rear displacement of the vehicle body (x br ), vehicle rear speed (x' br ) are replaced by vehicle body displacement (x b ), vehicle speed (x' b ), pitch angle (θ p ), pitch angular velocity (θ p ') is expressed as the following formula (2).

[0077] [Formula 2]

[0078]

[0079] Substituting the above equation (2) into the above equation (1), the motion equation of the pitching motion represented by the above equation (1) is rewritten as represented by the following equation (3).

[0080] [Formula 3]

[0081]

[0082] The longitudinal acceleration calculation unit 68 calculates the longitudinal acceleration (z") of the vehicle body based on the respective time series information of the acceleration operation amount and the braking operation amount of the vehicle 10 obtained by the information acquisition unit 41. When calculating the longitudinal acceleration (z") of the vehicle body, for example, the vehicle speed, the inclination angle of the road surface (uphill, downhill or flat road), the engine torque, etc. can also be referred to.

[0083] The longitudinal acceleration (z″) of the vehicle body calculated by the longitudinal acceleration calculation unit 68 is sent to the target pitch angle calculation unit 69 .

[0084] The target pitch angle calculation unit 69 calculates the target pitch angle θ of the vehicle body based on the longitudinal acceleration (z") of the vehicle body calculated by the longitudinal acceleration calculation unit 68. p .

[0085] Specifically, the Laplace transform is performed on the motion equation of the pitching motion shown in the above equation (3). The motion equation of the pitching motion after the Laplace transform is expressed as the following equation (4).

[0086] [Formula 4]

[0087]

[0088] In formula (4), s is the Laplace operator.

[0089] Next, for convenience, if the road height is input into x r (x rf , x rr ) is assumed to be zero (no unevenness in the road surface), and the vertical displacement of the unsprung member (wheel, etc.) 81 is x t (x tf , x tr ) is assumed to be zero and the assumed value is substituted into the above equation (4), then the target pitch angle θ of the vehicle body is p It can be expressed by the following formula (5). t The motion model used here assumes movement without road input, so for convenience, it is assumed to be zero. Therefore, if the motion model to be adopted assumes movement with road input, then an appropriate value can be set as the road displacement.

[0090] [Formula 5]

[0091]

[0092] As shown in the above formula (5), the target pitch angle θ p It can be expressed as a function of the front-to-back displacement z.

[0093] The target pitch angle θ of the vehicle body calculated by the target pitch angle calculation unit 69 is p The relevant information is sent to the first subtraction unit 65 and the third target load calculation unit 75 respectively.

[0094] The vehicle state estimation unit 63 estimates, based on the time series information of the sprung acceleration and the unsprung acceleration acquired by the information acquisition unit 41, the vehicle state quantity at the current point in time, for example, the "sprung velocity" as a first vehicle state quantity (sprung state quantity) and the "time integral value of the sprung velocity" as a second vehicle state quantity.

[0095] The first vehicle state quantity (sprung velocity) and the second vehicle state quantity (time-integrated value of the sprung velocity) estimated by the vehicle state estimation unit 63 are sent to the first subtraction unit 65 and the second subtraction unit 67 , respectively.

[0096] The first subtraction unit 65 subtracts the target pitch angle velocity θ′ of the host vehicle 10 calculated by the target pitch angle calculation unit 69 from the current first vehicle state quantity (sprung velocity) estimated by the vehicle state estimation unit 63. p Thus, the first vehicle state quantity (sprung velocity) is corrected by removing the pitch angular velocity component from the current first vehicle state quantity (sprung velocity). The first subtraction unit 65 corresponds to the "sprung state quantity correction unit" of the present invention.

[0097] The first vehicle state quantity (sprung velocity) corrected by the first subtraction unit 65 is sent to the first target load calculation unit 71 .

[0098] The second subtraction unit 67 subtracts the current second vehicle state quantity (the time-integrated value of the sprung velocity) estimated by the vehicle state estimation unit 63 from the current vehicle height acquired by the information acquisition unit 41. This corrects the vehicle height by removing the vehicle height component resulting from changes in the sprung velocity from the current vehicle height.

[0099] The vehicle height corrected by the second subtraction unit 67 is sent to the second target load calculation unit 73 .

[0100] The first target load calculation unit 71 calculates a first target load related to skyhook control based on the first vehicle state quantity (sprung velocity) corrected by the first subtraction unit 65. Specifically, for example, the first target load calculation unit 71 calculates the first target load by multiplying the corrected first vehicle state quantity (sprung velocity) by a skyhook damping coefficient using a control principle based on skyhook theory.

[0101] The first target load calculated by the first target load calculation unit 71 is sent to the integration unit 77 .

[0102] The second target load calculation unit 73 calculates a second target load related to the look-ahead control based on the vehicle height (actual road surface height) corrected by the second subtraction unit 67. Specifically, for example, the second target load calculation unit 73 calculates the second target load by multiplying the corrected vehicle height (actual road surface height) by the look-ahead control gain using a control principle based on the skyhook theory.

[0103] The second target load calculated by the second target load calculation unit 73 is sent to the integration unit 77 .

[0104] The third target load calculation unit 75 calculates the target load based on the target pitch angle θ of the host vehicle 10 calculated by the target pitch angle calculation unit 69. p Calculate the third target load (F f , F r ).

[0105] Specifically, the target pitch angle θ calculated above is used to achieve p The third target load (F f , F r ) can be calculated by the following steps.

[0106] First, as a vehicle model assumption Figure 5B The single wheel model shown is used to calculate the equation of motion of the vehicle body. The equation of motion of the vehicle body can be expressed by the following equation (6). However, it is not necessary to assume that the vehicle model Figure 5B The single wheel model shown is based on Figure 5A The model directly calculates the thrust.

[0107] [Formula 6]

[0108]

[0109] Next, the Laplace transform is performed on the equation of motion of the vehicle body represented by the above equation (6). The equation of motion of the vehicle body after the Laplace transform is represented by the following equation (7).

[0110] [Formula 7]

[0111]

[0112] In formula (7), s is the Laplace operator.

[0113] Next, for convenience, enter the road height into x r (x rf , x rr ) is assumed to be zero (no unevenness in the road surface), and the vertical displacement of the unsprung member (wheel, etc.) 81 is x t (x tf , x tr ) is assumed to be zero. Substitute this assumed value into the above equation (7), and substitute the above equation (2) into the above equation (7). The equation of motion of the vehicle body after the Laplace transform shown in the above equation (7) can then be expressed as the following equation (8).

[0114] [Formula 8]

[0115]

[0116] The third target load calculation unit 75 calculates the load required to achieve the target pitch angle θ as shown in the above equation (8). p The third target load (F f , F r ).

[0117] The third target load (F f , F r ) is sent to the merging unit 77.

[0118] The combining unit 77 combines the first target load calculated by the first target load calculating unit 71 , the second target load calculated by the second target load calculating unit 73 , and the third target load calculated by the third target load calculating unit 75 , and outputs the combined target load.

[0119] The combined target load combined by the combining unit 77 is sent to the load control unit 45 .

[0120] [Operation of the Electric Suspension Device 11]

[0121] Next, refer to Figure 6 The operation of the electric suspension device 11 according to the embodiment of the present invention will be described. Figure 6 This is a flowchart for explaining the operation of the electric suspension device 11 according to the embodiment of the present invention.

[0122] exist Figure 6In step S11 shown, the information acquisition unit 41 of the load control ECU 15 acquires various information including the accelerator operation amount, brake operation amount, preview image, vehicle height, sprung acceleration, and unsprung acceleration of the host vehicle 10 .

[0123] In step S12, the target pitch angle derivation unit 61 of the load control ECU 15 derives the target pitch angle θ of the host vehicle 10. p .

[0124] That is, the longitudinal acceleration calculation unit 68 included in the target pitch angle derivation unit 61 calculates the longitudinal acceleration (z″) of the host vehicle 10 based on the accelerator operation amount and the brake operation amount of the host vehicle 10 acquired by the information acquisition unit 41 .

[0125] Next, the target pitch angle calculation unit 69 included in the target pitch angle derivation unit 61 calculates the target pitch angle θ of the host vehicle 10 based on the longitudinal acceleration (z") of the host vehicle 10 calculated by the longitudinal acceleration calculation unit 68. p .

[0126] In step S13 , the vehicle state estimation unit 63 of the load control ECU 15 estimates the current sprung state quantity (first vehicle state quantity: sprung velocity) based on the time series information of the sprung acceleration and the unsprung acceleration acquired by the information acquisition unit 41 .

[0127] In step S14, the first subtraction unit 65 of the load control ECU 15 subtracts the target pitch angular velocity (θ'p) of the host vehicle 10 calculated by the target pitch angle calculation unit 69 from the current first vehicle state quantity (sprung velocity) estimated by the vehicle state estimation unit 63. Thus, the first vehicle state quantity (sprung velocity) is corrected by removing the pitch angular velocity component from the current first vehicle state quantity (sprung velocity).

[0128] In step S15, the second subtraction unit 67 of the load control ECU 15 subtracts the current second vehicle state quantity (the time-integrated value of the sprung velocity) estimated by the vehicle state estimation unit 63 from the current vehicle height acquired by the information acquisition unit 41. This corrects the vehicle height by removing the vehicle height component resulting from changes in the sprung velocity from the current vehicle height.

[0129] In step S16 , the target load calculation unit 43 of the load control ECU 15 calculates the combined target load.

[0130] Specifically, the first target load calculation unit 71 calculates the first target load related to skyhook control based on the first vehicle state quantity (sprung velocity) corrected by the first subtraction unit 65. The first target load calculation unit 71 calculates the first target load for suppressing vibrations that cannot be addressed by the second target load related to the look-ahead control described below (e.g., vibrations caused by factors other than road surface input).

[0131] The second target load calculation unit 73 calculates a second target load related to the look-ahead control based on the vehicle height (actual road surface height) corrected by the second subtraction unit 67. The second target load calculation unit 73 calculates the second target load for suppressing vibrations caused by road surface input.

[0132] The third target load calculation unit 75 calculates the target load based on the target pitch angle θ of the host vehicle 10 calculated by the target pitch angle calculation unit 69. p The third target load calculation unit 75 calculates the target pitch angle θ for generating the vehicle 10. p The third target load.

[0133] The combining unit 77 combines the first target load calculated by the first target load calculating unit 71 , the second target load calculated by the second target load calculating unit 73 , and the third target load calculated by the third target load calculating unit 75 , and outputs the combined target load.

[0134] In step S17, the load control unit 45 of the load control ECU 15 performs load control on the electromagnetic actuator 13 according to the combined target load, which is the calculation result of step S16. The load control ECU 15 then terminates the series of processing flows.

[0135] [Operation and Effect of the Electric Suspension Device 11 According to the Embodiment of the Present Invention]

[0136] The electric suspension device 11 based on the first viewpoint includes: an actuator (electromagnetic actuator 13), which is provided between the body and wheels of the vehicle 10 and generates a load for attenuating the vibration of the body; an information acquisition unit 41, which acquires information related to the sprung state quantity and the driving surface state of the sprung load (body) of the vehicle 10; a target load calculation unit 43, which calculates a first target load related to skyhook control based on the sprung state quantity, and calculates a second target load related to predictive control based on the driving surface state; and a load control unit 45, which uses the calculation result of the target load calculation unit 43 to perform load control of the electromagnetic actuator 13.

[0137] The information acquisition unit 41 further acquires information related to the longitudinal acceleration and deceleration of the vehicle 10 and includes a target pitch angle derivation unit 61 for deriving a target pitch angle of the vehicle 10 based on the information. The information related to the longitudinal acceleration and deceleration of the vehicle 10 can be, for example, information such as the amount of accelerator operation or the amount of brake operation of the vehicle 10.

[0138] The target load calculation unit 43 further calculates the target pitch angle θ based on the target pitch angle deriving unit 61. p The load control unit 45 generates a third target load related to pitch control and calculates a combined target load by combining the first target load, the second target load, and the third target load. The load control unit 45 performs load control on the electromagnetic actuator 13 using the combined target load.

[0139] Here, let's imagine a situation where vehicle 10, equipped with skyhook control and look-ahead control, is engaged in sport driving. In this scenario, the control device inherently operates to suppress the pitching (diving) motion that occurs when vehicle 10 brakes. Consequently, during braking in a sport driving scenario, the driver cannot flexibly utilize the entrainment phenomenon associated with the pitching (diving) motion to flexibly switch the direction of travel of vehicle 10. This impairs the sense of unity between driver and vehicle during sport driving. Consequently, there is a risk that the driver will experience a sense of discomfort.

[0140] Therefore, in the electric suspension device 11 based on the first aspect, the target load calculation unit 43 further calculates the target pitch angle θ derived by the target pitch angle derivation unit 61. p The load control unit 45 generates a third target load related to pitch control and calculates a combined target load by combining the first target load, the second target load, and the third target load. The load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load.

[0141] According to the electric suspension device 11 based on the first viewpoint, a combined target load is calculated by combining the third target load related to pitch generation control in addition to the first target load related to skyhook control and the second target load related to anticipation control, and the combined target load is used to control the load of the electromagnetic actuator 13. Therefore, even when braking in a sporty driving scenario, a comfortable ride accompanied by a sense of unity between the driver and the vehicle can be achieved.

[0142] Furthermore, according to the electric suspension device 11 based on the first aspect, when the vehicle 10 is experiencing pitching motion, such as during braking in a sporty driving situation, the pitching motion of the vehicle 10 is suppressed, thereby reducing power consumption accordingly. As a result, it is expected that the onboard battery will also have the effects of protecting against heat and extending its life.

[0143] The electric suspension device 11 according to the second aspect may have the following configuration: in the electric suspension device 11 according to the first aspect, the electric suspension device 11 may further include a sprung state quantity correction unit (first subtraction unit 65) for subtracting a value based on the target pitch angle θ from the sprung state quantity (sprung velocity). p The sprung state amount is corrected based on the pitch angular velocity component of the sprung state amount, and the target load calculation unit 43 calculates the first target load related to the skyhook control based on the corrected sprung state amount.

[0144] In the electric suspension device 11 according to the second aspect, the sprung state quantity correction unit (first subtraction unit 65) subtracts the target pitch angle θ from the sprung state quantity, i.e., the sprung velocity, obtained by the information acquisition unit 41. p The pitch angular velocity component of the sprung state quantity (sprung velocity) is corrected by removing the pitch angular velocity component from the current sprung velocity.

[0145] In short, since the target pitch angle velocity component is removed from the basic data (sprung velocity) for obtaining the first target load related to the skyhook control, the target pitch angle θ related to the skyhook control can be eliminated. p impact.

[0146] According to the electric suspension device 11 based on the second aspect, the target pitch angle θ is subtracted from the sprung velocity as the sprung state quantity. p The pitch angular velocity component of the sprung state quantity (sprung velocity) is corrected by removing the pitch angular velocity component from the current sprung velocity. This avoids competition between skyhook control and pitch generation control due to the common pitch angular velocity component, as compared to the electric suspension device 11 based on the first aspect. Consequently, errors in the combined target load can be suppressed, enabling highly accurate load control.

[0147] Furthermore, the electric suspension device 11 according to the third aspect may have the following configuration: In the electric suspension device 11 according to the first aspect or the second aspect, the target pitch angle derivation unit 61 (see Figure 4 ) in the target pitch angle θ p The derivation of the above-mentioned equations uses a virtual shock absorber 87 (refer to Figure 5A ) is performed according to the motion equation of the pitching action of the attenuation coefficient Cs of the above-mentioned virtual shock absorber 87 (refer to Formula 1), and the attenuation coefficient Cs of the above-mentioned virtual shock absorber 87 is set to an appropriate value corresponding to the user's preference related to the pitching action of the vehicle 10.

[0148] According to the electric suspension device 11 based on the third aspect, the target pitch angle θ in the target pitch angle derivation unit 61 is pThe derivation is performed using a motion equation for the pitching motion including the attenuation coefficient Cs of a hypothetical shock absorber 87 provided between the body (sprung) and the wheel (unsprung) of the vehicle 10. The attenuation coefficient Cs of the hypothetical shock absorber 87 is set to an appropriate value corresponding to the user's preference in relation to the pitching motion of the vehicle 10. Therefore, compared with the electric suspension device 11 based on the first viewpoint or the second viewpoint, a comfortable ride feeling that further enhances the sense of unity between the driver and the vehicle can be concretized.

[0149] [Other Implementation Methods]

[0150] The multiple embodiments described above illustrate examples of the present invention. Therefore, the technical scope of the present invention is not limited to these embodiments. This is because the present invention can be implemented in various ways without departing from its gist or its main features.

[0151] For example, in the description of the electric suspension device 11 according to the embodiment of the present invention, an example is given in which a total of four electromagnetic actuators 13 are arranged on both the front wheels (left front wheel and right front wheel) and the rear wheels (left rear wheel and right rear wheel). However, the present invention is not limited to this example. A configuration in which a total of two electromagnetic actuators 13 are arranged on either the front wheel or the rear wheel may also be employed.

[0152] The description of the electric suspension device 11 according to the embodiment of the present invention mentions the load control unit 45 that independently controls the loads of the plurality of electromagnetic actuators 13. Specifically, the load control unit 45 independently controls the loads of the electromagnetic actuators 13 provided on each of the four wheels.

[0153] However, the load control of the electromagnetic actuators 13 provided for the four wheels may be performed independently for the front and rear wheels, or independently for the left and right wheels.

[0154] Furthermore, while the electric suspension device 11 according to the embodiment of the present invention is described, an example of the present invention being applied to a vehicle during braking in a sporty driving situation is given. However, the present invention is not limited to this example. The present invention can also be applied to a vehicle during braking in a normal driving situation.

[0155] Finally, in the description of the electric suspension device 11 according to the embodiment of the present invention, a ball screw system has been exemplified as the driving mechanism of the electromagnetic actuator 13 , but the present invention is not limited to this example.

[0156] As the driving mechanism of the electromagnetic actuator 13 , any type of driving mechanism, such as a linear motor type, a rack and pinion type, or a rotary type, may be adopted.

Claims

1. An electric suspension device comprising: an actuator provided between a vehicle body and a wheel and generating a load for attenuating vibration of the vehicle body; an information acquisition unit for acquiring information on a sprung state quantity and a road surface state of the vehicle; a target load calculation unit that calculates a first target load related to skyhook control based on the sprung state quantity and calculates a second target load related to look-ahead control based on the traveling road surface state; and a load control unit that performs load control on the actuator using the calculation result of the target load calculation unit, The electric suspension device is characterized in that: The information acquisition unit further acquires information related to the front and rear acceleration and deceleration of the vehicle. Also features: a target pitch angle deriving unit for deriving a target pitch angle of the vehicle based on the information related to the longitudinal acceleration / deceleration; and a sprung state quantity correction unit that corrects the sprung state quantity by subtracting a pitch angular velocity component based on the target pitch angle derived by the target pitch angle derivation unit from a sprung velocity serving as the sprung state quantity, wherein the target load calculation unit calculates a first target load related to the skyhook control based on the corrected sprung state quantity, further calculates a third target load related to the pitch generation control based on the target pitch angle, and calculates a combined target load that combines the first target load, the second target load, and the third target load. The load control unit performs load control of the actuator using the combined target load.

2. The electric suspension device according to claim 1, wherein: The target pitch angle derivation unit derives the target pitch angle using a motion equation of a pitching motion including a damping coefficient of a virtual shock absorber provided between a body and wheels of the vehicle. The damping coefficient of the virtual shock absorber is set to an appropriate value corresponding to the user's preference in relation to the pitching behavior of the vehicle.

3. An electric suspension device comprising: an actuator provided between a vehicle body and a wheel and generating a load for attenuating vibration of the vehicle body; an information acquisition unit for acquiring information on a sprung state quantity and a road surface state of the vehicle; a target load calculation unit that calculates a first target load related to skyhook control based on the sprung state quantity and calculates a second target load related to look-ahead control based on the traveling road surface state; and a load control unit that performs load control on the actuator using the calculation result of the target load calculation unit, The electric suspension device is characterized in that: The information acquisition unit further acquires information related to the front and rear acceleration and deceleration of the vehicle. further comprising a target pitch angle deriving unit for deriving a target pitch angle of the vehicle based on the information related to the longitudinal acceleration and deceleration; The target pitch angle derivation unit derives the target pitch angle using a motion equation of a pitching motion including a damping coefficient of a virtual shock absorber provided between a body and wheels of the vehicle. The damping coefficient of the virtual shock absorber is set to an appropriate value corresponding to the user's preference in relation to the pitching behavior of the vehicle. The target load calculation unit further calculates a third target load related to pitch generation control based on the target pitch angle derived by the target pitch angle deriving unit, and calculates a combined target load by combining the first target load, the second target load, and the third target load. The load control unit performs load control of the actuator using the combined target load.

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