Electric suspension

Abstract

Provided is an electric suspension device that can buffer a large input and maintain a comfortable ride even when a large input is generated in a shock absorber during vehicle travel. The electric suspension device includes: an electromagnetic actuator that generates a load for attenuating the vibration of a vehicle body; an information acquisition unit (41) that acquires information about the sprung state quantity and the state of a driving road surface 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 a second target load related to predictive control based on the driving road surface state; and a load control unit that performs load control of the electromagnetic actuator. The target load calculation unit calculates a combined target load by combining the first target load and the second target load with a third target load related to virtual spring force control based on a stroke position. The load control unit uses the combined target load to perform load control 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 of a vehicle 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 that is provided between a vehicle body and wheels of a vehicle and generates a load for attenuating vibration of the vehicle body (see, for example, Patent Document 1).

[0003] The electric suspension device of Patent Document 1 includes a control device that controls a control object capable of controlling the output in a system that outputs a response to the influence of a disturbance input with a time delay. The control device generates a control instruction for eliminating the influence of the disturbance from the output based on a transfer function from the disturbance input to the output of the system, a transfer function from a control instruction 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, so that the vibration of the vehicle body can be suppressed.

[0005] In addition, Patent Document 2 discloses an invention of a suspension device having an upper jump stopper made of a buffer material. In the suspension device, when a large input is generated in the shock absorber due to uneven road surface, the upper jump stopper abuts against the end of the shock absorber to absorb the impact. As a result, the bottoming feeling of the shock absorber is alleviated, and the ride quality of the vehicle is maintained well.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-134899

[0007] Patent Document 2: Japanese Patent Application Publication No. 2017-141900 Summary of the invention

[0008] In addition, the invention of the electric suspension device of Patent Document 1 does not describe or suggest how to cushion the impact when a large input is generated in the shock absorber due to uneven road surface, etc. Therefore, when a large input is generated in the shock absorber during vehicle travel, there is a concern that the ride quality of the vehicle may be impaired.

[0009] 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 buffer a large input and maintain a comfortable ride even when a large input is generated in a shock absorber during vehicle travel.

[0010] In order to achieve the above 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 stroke position of the above-mentioned actuator, and also has an evaluation unit that evaluates whether the stroke position has reached an uncommon area exceeding the common area based on the information related to the above-mentioned stroke position, when the result of the evaluation obtained by the above-mentioned evaluation unit is an evaluation to the effect that the stroke position has reached the above-mentioned uncommon area, the above-mentioned target load calculation unit further calculates a third target load involving virtual spring force control based on the stroke position, 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.

[0011] Effects of the Invention

[0012] According to the present invention, even when a large input is generated in the shock absorber during vehicle running, the large input can be buffered while maintaining a comfortable ride feeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the overall structure of an electric suspension device according to an embodiment of the present invention.

[0014] 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.

[0015] Figure 3 It is a structural diagram of the inside and peripheral parts of the load control ECU included in the electric suspension device according to the embodiment of the present invention.

[0016] 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.

[0017] Figure 5A It is a diagram for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0018] Figure 5BIt is a diagram for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0019] Figure 6 This is a flowchart for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0020] Description of Reference Numerals

[0021] 10 Vehicles

[0022] 11 Electric suspension

[0023] 13 Electromagnetic actuator (actuator)

[0024] 41 Information Acquisition Department

[0025] 43 Target load calculation unit

[0026] 45 Load Control Unit

[0027] 61 Evaluation Department

[0028] 63 Vehicle status estimation unit (information acquisition unit)

[0029] 65 Subtraction

[0030] 67 Hypothetical road surface input evaluation unit (evaluation unit)

[0031] 69 Bump State Evaluation Department (Evaluation Department)

[0032] 71 First target load calculation unit (target load calculation unit)

[0033] 73 Second target load calculation unit (target load calculation unit)

[0034] 75 3rd target load calculation unit (target load calculation unit)

[0035] 77 Merging unit (target load calculation unit) DETAILED DESCRIPTION

[0036] 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.

[0037] 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 the components are deformed or exaggerated and schematically represented.

[0038] [Basic structure common to the electric suspension device 11 according to the embodiment of the present invention]

[0039] 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.

[0040] Figure 1 This is a diagram showing an overall structure 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 .

[0041] like Figure 1 As shown in FIG. 1 , 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 vehicle itself) 10, and a load control ECU 15. The plurality of electromagnetic actuators 13 and the load control ECU 15 are connected to each other via power supply lines 14 (see FIG. 1 ). Figure 1 solid line) and signal line 16 (refer to 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.

[0042] In this embodiment, a total of four electromagnetic actuators 13 are arranged for each wheel including the front wheel (left front wheel, right front wheel) and the rear wheel (left rear wheel, right rear wheel). The electromagnetic actuators 13 arranged for each wheel are load-controlled independently according to the extension and retraction operation of each wheel.

[0043] In the embodiment of the present invention, the plurality of electromagnetic actuators 13 have a common structure unless otherwise specified. Therefore, the structure of one electromagnetic actuator 13 will be described instead of describing the plurality of electromagnetic actuators 13 .

[0044] like Figure 2 As shown, the electromagnetic actuator 13 is configured to include 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 .

[0045] The base shell 17 supports the base end side of the ball screw shaft 23 rotatably around the axis via the ball bearing 21. The outer tube 19 is provided on the base shell 17, and accommodates the ball screw mechanism 18 including the ball screw shaft 23, a plurality of balls 25, and a nut 27. The plurality of balls 25 roll along the screw groove of the ball screw shaft 23. The nut 27 engages with the ball screw shaft 23 via the plurality of balls 25, and converts the rotational motion of the ball screw shaft 23 into a linear motion. The inner tube 29 connected to the nut 27 is integrated with the nut 27 and displaced along the axial direction of the outer tube 19.

[0046] In order to transmit the rotational driving force to the ball screw shaft 23, Figure 2 As shown in FIG. 1 , 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 on the base housing 17. The pulleys 33 are mounted on the motor shaft 31a of the electric motor 31 and the ball screw shaft 23, respectively. The belt member 35 for transmitting the rotational driving force of the electric motor 31 to the ball screw shaft 23 is suspended on the pair of pulleys 33.

[0047] The electric motor 31 is provided with a resolver 37 for detecting 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 the signal line 16. The electric motor 31 is rotationally driven and controlled according to the load control power supplied by the load control ECU 15 to each of the plurality of electromagnetic actuators 13 via the power supply line 14.

[0048] 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 roughly 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.

[0049] 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 an unsprung member (lower arm on the wheel side, knuckle, etc.) not shown. On the other hand, the upper end portion 29a of the inner tube 29 is connected and fixed to a sprung member (strut tower on the vehicle body side, etc.) not shown.

[0050] In short, the electromagnetic actuator 13 is arranged in parallel with a spring member (suspension) (not shown) provided between a sprung member (vehicle body) and an unsprung member (wheel with tires etc.) of the vehicle 10. The electromagnetic actuator 13 functions as a virtual shock absorber for buffering the expansion and contraction force of the spring member (suspension).

[0051] The electromagnetic actuator 13 constructed as described above operates as follows. That is, for example, consider a situation where a driving force involving upward vibration is input to the connecting portion 39 from the wheel side of the vehicle 10. In this case, the inner tube 29 and the nut 27 will be integrally lowered relative to the outer tube 19 to which the driving force involving upward vibration is applied. Influenced by this, the ball screw shaft 23 will rotate in a direction that follows the descent of the nut 27. At this time, the rotational driving force of the electric motor 31 is generated in a direction that hinders 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 causes a reaction force (damping force) to act on the ball screw shaft 23 against the urging force associated with the upward vibration, thereby damping the vibration that is to be transmitted from the wheel side to the vehicle body side.

[0053] [Internal structure of load control ECU 15]

[0054] Next, refer to Figure 3 The configuration of the interior and the periphery 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 configuration diagram of the inside and peripheral parts of the load control ECU 15 provided in the electric suspension device 11 according to the embodiment of the present invention.

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

[0057] The load control ECU 15 provided in the electric suspension device 11 according to the embodiment of the present invention is configured to include a microcomputer that performs various calculations. Figure 3 As shown, the load control ECU 15 has a load control function, which performs load control on multiple electromagnetic actuators 13 based on the rotation angle signal of the stroke position ST of the electric motor 31 detected by the rotary transformer 37, the combined target load (details will be described later), the motor current applied to the electric motor 31, etc., thereby generating the load involved in the attenuation action and extension action of the electromagnetic actuator 13.

[0058] In order to achieve such load control functions, such as Figure 3 As shown, the load control ECU 15 is configured to include an information acquisition unit 41 , an evaluation unit 61 , a target load calculation unit 43 , and a load control unit 45 .

[0059] like Figure 3 As shown, the information acquisition unit 41 acquires the vehicle speed of the host vehicle 10, the stroke position ST of the electromagnetic actuator 13, and time series information on the road surface state of the road surface in the traveling direction of the vehicle 10, and acquires preview image and vehicle height information respectively.

[0060] The vehicle speed information of the host vehicle 10 may be acquired by the vehicle speed sensor 51 that detects the vehicle speed of the host vehicle 10 .

[0061] The information on the stroke position ST of the electromagnetic actuator 13 may be acquired from, for example, a rotation angle signal of the electric motor 31 detected by the resolver 37 .

[0062] On the other hand, the preview image information may be obtained by, for example, a camera 42 provided on the vehicle 10 or by an external sensor such as a radar or a laser radar. In addition, the vehicle height information may be obtained by, for example, a vehicle height sensor 55 that detects the vehicle height of the vehicle 10 .

[0063] In addition, the information acquisition unit 41 acquires time series information of each of the sprung acceleration and the unsprung acceleration. The information of the sprung acceleration can be acquired based on the detection value of the sprung acceleration sensor 57 provided on the sprung member (vehicle body) of the vehicle 10. In addition, the information of the unsprung acceleration can be acquired based on the detection value of the unsprung acceleration sensor 59 provided on the unsprung member (wheel, etc.) of the vehicle 10.

[0064] The vehicle speed, the stroke position ST of the electromagnetic actuator 13 , the preview image, the sprung acceleration, the unsprung acceleration, the vehicle height, and the information on the motor current of the electric motor 31 acquired by the information acquisition unit 41 are sent to the evaluation unit 61 and the target load calculation unit 43 , respectively.

[0065] The evaluation unit 61 evaluates whether the electromagnetic actuator 13 has a risk of falling into a full-blown state on either the extension side or the contraction side, based on the information of the preview image acquired by the information acquisition unit 41 and the information related to the stroke position ST of the electromagnetic actuator 13. The structure of the evaluation unit 61 will be described in detail later.

[0066] The evaluation result obtained by the evaluation unit 61 is sent to the target load calculation unit 43 .

[0067] The target load calculation unit 43 has a function of obtaining, by calculation, 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 based on the above-mentioned various information acquired by the information acquisition unit 41 .

[0068] In fact, the target load calculation unit 43 is configured to include a first target load calculation unit 71 that calculates a first target load related to the skyhook control, a second target load calculation unit 73 that calculates a second target load related to the foresight control, and a third target load calculation unit 75 that calculates a third target load related to the virtual spring force 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.

[0069] The load control unit 45 calculates a target current value that can realize the combined target load obtained by the target load calculation unit 43. Next, the load control unit 45 performs drive control of the electric motors 31 respectively provided in the plurality of electromagnetic actuators 13 so that the motor current of the electric motor 31 follows the calculated target current value. The load control of each electric motor 31 is performed independently in each of the plurality of electromagnetic actuators 13.

[0070] [Main Configuration of Load Control ECU 15 Included in Electric Suspension Device 11]

[0071] 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.

[0072] 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 .

[0073] like Figure 4 As shown, the load control ECU 15 provided in the electric suspension device 11 includes an evaluation unit 61, a vehicle state estimation unit 63, a subtraction unit 65, 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 serves 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.

[0074] The evaluation unit 61 is configured to include a virtual road surface input evaluation unit 67 and a pitch state evaluation unit 69 .

[0075] The virtual road input evaluation unit 67 included in the evaluation unit 61 evaluates the virtual road input level VR based on the information on the road surface state ahead of the vehicle 10 in the traveling direction in the preview image acquired by the information acquisition unit 41. Here, the virtual road input refers to the virtual road input estimated based on the preview image.

[0076] Specifically, when the virtual road surface input evaluation unit 67 recognizes the presence of a hole called a pothole on the road surface through preview image analysis, for example, the virtual road surface input level VR is evaluated based on the size and depth of the pothole, the distance to the pothole, the speed of the host vehicle 10, etc. The evaluation result of the virtual road surface input level VR is sent to the bumpy state evaluation unit 69.

[0077] The pitch state evaluation unit 69 of the evaluation unit 61 determines whether the stroke position ST of the electromagnetic actuator 13 has reached an unusually used region (see FIG. 1 ) exceeding the normal used region based on the information on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41. Figure 5A If the stroke position ST of the electromagnetic actuator 13 reaches an unusual region beyond the normal region, it means that the electromagnetic actuator 13 has a risk of jumping on one side of the extension side and the contraction side.

[0078] Describe in detail, such as Figure 5A As shown, the turbulence state evaluation unit 69 evaluates whether the stroke position ST of the electromagnetic actuator 13 has reached the unusual region based on whether the stroke position ST exceeds a predetermined standard critical threshold value STct0. In addition, the standard critical threshold value STct0 may be appropriately set to a standard stroke position ST at which it is estimated that the electromagnetic actuator 13 has a risk of falling into a hopping state.

[0079] In addition, the pitching state evaluation unit 69 performs evaluation related to the pitching state based on the evaluation result (the virtual road surface input level VR) related to the virtual road surface input sent from the virtual road surface input evaluation unit 67. Specifically, the pitching state evaluation unit 69 evaluates whether the virtual road surface input level VR exceeds a predetermined first road surface input threshold VRth1 (equivalent to the "road surface input threshold" of the present invention), for example.

[0080] If the evaluation result indicates that the virtual road surface input level VR exceeds the first road surface input threshold VRth1 (VR>VRth1), the pitching state evaluation unit 69 evaluates that there is a risk of falling into the bouncing state (the virtual road surface input level is high).

[0081] On the other hand, when it is evaluated that the virtual road surface input level VR does not exceed the first road surface input threshold VRth1 (VR=<VRth1), the pitching state evaluation unit 69 evaluates that there is no risk of falling into the bouncing state (the virtual road surface input level is low).

[0082] When the bumping state evaluation unit 69 evaluates that the virtual road surface input level VR exceeds the first road surface input threshold VRth1 (VR>VRth1: there is a risk of falling into a bouncing state), it further evaluates whether the virtual road surface input level VR exceeds the second road surface input threshold VRth2.

[0083] If the evaluation result indicates that the virtual road surface input level VR exceeds the second road surface input threshold VRth2 (VR>VRth2>VRth1), the pitching state evaluation unit 69 evaluates that the probability of falling into the bouncing state is particularly high (the virtual road surface input level is particularly high).

[0084] On the other hand, when it is evaluated that the virtual road surface input level VR does not exceed the second road surface input threshold VRth2 (VRth2=>VR>VRth1), the pitching state evaluation unit 69 evaluates that there is a risk of falling into the bouncing state (the virtual road surface input level is high).

[0085] In short, the bumpy state evaluation unit 69 performs three-level evaluation (low / high / very high) related to the bumpy state based on the evaluation result related to the virtual road input level VR sent from the virtual road input evaluation unit 67. However, the number of levels related to the bumpy state evaluation is not particularly limited as long as there are multiple levels.

[0086] The information on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41 , the evaluation result of whether the stroke position ST has reached the non-usable region by the pitching state evaluation unit 69 , and the pitching state evaluation result are respectively sent to the third target load calculation unit 75 .

[0087] The vehicle state estimation unit 63 estimates the vehicle state quantity at the current point in time, for example, the "sprung speed" as the first vehicle state quantity (sprung state quantity) and the "time integral value of the sprung speed" as the second vehicle state quantity, based on the respective timing information of the sprung acceleration and the unsprung acceleration acquired by the information acquisition unit 41.

[0088] The first vehicle state amount (sprung velocity) and the second vehicle state amount (time-integrated value of the sprung velocity) estimated by the vehicle state estimation unit 63 are sent to the first target load calculation unit 71 and the subtraction unit 65 , respectively.

[0089] The subtracting unit 65 subtracts the current second vehicle state amount (time integral value of sprung velocity) estimated by the vehicle state estimating unit 63 from the current vehicle height acquired by the information acquiring unit 41. Thus, the vehicle height is corrected by removing the vehicle height component resulting from the sprung velocity change from the current vehicle height.

[0090] The vehicle height corrected by the subtraction unit 65 is sent to the second target load calculation unit 73 .

[0091] The first target load calculation unit 71 calculates a first target load related to the skyhook control based on the first vehicle state quantity (sprung speed) estimated by the vehicle state estimation unit 63. Specifically, for example, the first target load calculation unit 71 calculates the first target load by multiplying the first vehicle state quantity (sprung speed) by a skyhook damping coefficient using a control rule based on the skyhook theory.

[0092] The first target load calculated by the first target load calculation unit 71 is sent to the integrating unit 77 .

[0093] The second target load calculation unit 73 calculates the second target load related to the look-ahead control based on the vehicle height (actual road surface height) corrected by the subtraction unit 65. 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 rule based on the skyhook theory.

[0094] The second target load calculated by the second target load calculation unit 73 is sent to the integrating unit 77 .

[0095] The third target load calculation unit 75 calculates the anti-bumping characteristic (see FIG. 1 ) which increases substantially linearly with respect to the change in the third target load with respect to the change in the stroke position ST of the electromagnetic actuator 13, based on the pitching state evaluation result (low / high / extra high) obtained by the pitching state evaluation unit 69. Figure 5A , Figure 5B ) to make settings.

[0096] Next, the third target load calculation unit 75 calculates a third target load related to the virtual spring force control for realizing the anti-bumping function based on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41 and the anti-bumping characteristic set as described above.

[0097] The third target load calculated by the third target load calculation unit 75 is sent to the integration unit 77. The function of the third target load calculation unit 75 will be described in detail later.

[0098] 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 a combined target load.

[0099] The combined target load combined by the combining unit 77 is sent to the load control unit 45 .

[0100] [Operation of the electric suspension device 11]

[0101] 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.

[0102] Among them, Figure 6 In the example shown, it is assumed that the stroke position ST of the electromagnetic actuator 13 exceeds a predetermined standard critical threshold value STct0.

[0103] exist Figure 6 In step S11 shown, the information acquisition unit 41 of the load control ECU 15 acquires the vehicle speed of the vehicle 10, the stroke position ST of the electromagnetic actuator 13, and time series information of the driving road surface state in the traveling direction of the vehicle 10, and acquires various information including a preview image and a vehicle height.

[0104] In steps S12 to S13 , the evaluation unit 61 evaluates whether the electromagnetic actuator 13 is likely to jump up on either the extension side or the contraction side based on the preview image information acquired by the information acquisition unit 41 and the information on the stroke position ST of the electromagnetic actuator 13 .

[0105] First, in step S12 , the virtual road surface input evaluation unit 67 included in the evaluation unit 61 evaluates the virtual road surface input level VR based on the information on the state of the road surface ahead in the traveling direction of the host vehicle 10 in the preview image acquired by the information acquisition unit 41 .

[0106] That is, when the virtual road surface input evaluation unit 67 recognizes the presence of a hole called a pothole on the road surface through preview image analysis, for example, the virtual road surface input level VR is evaluated based on the size and depth of the pothole, the distance to the pothole, the speed of the host vehicle 10, etc. The evaluation result regarding the virtual road surface input level VR is sent to the bumpy state evaluation unit 69.

[0107] In step S13, the pitching state evaluation unit 69 of the evaluation unit 61 determines whether the stroke position ST of the electromagnetic actuator 13 has reached an unusually used area (see FIG. 1 ) exceeding the normal use area based on the information on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41. Figure 5A ) for evaluation.

[0108] Furthermore, the pitching state evaluating unit 69 performs three-level evaluation (low / high / very high) on the pitching state based on the evaluation result regarding the virtual road surface input level VR sent from the virtual road surface input evaluating unit 67 .

[0109] The information on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41 , the evaluation result of whether the stroke position ST has reached the non-usable region by the pitching state evaluation unit 69 , and the pitching state evaluation result are respectively sent to the third target load calculation unit 75 .

[0110] In step S14, the first target load calculation unit 71 of the load control ECU 15 calculates the first target load related to the skyhook control based on the current first vehicle state quantity (sprung speed) estimated by the vehicle state estimation unit 63. In the first target load calculation unit 71, the first target load for suppressing vibrations (for example, vibrations caused by reasons other than road surface input) that cannot be dealt with by the second target load related to the predictive control described below is calculated.

[0111] In step S15, the subtraction unit 65 of the load control ECU 15 subtracts the current second vehicle state quantity (time integral 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. Thus, the vehicle height is corrected by removing the vehicle height component resulting from the sprung velocity change from the current vehicle height.

[0112] The second target load calculation unit 73 of the load control ECU 15 calculates the second target load related to the look-ahead control based on the vehicle height (actual road surface height) corrected by the subtraction unit 65. The second target load calculation unit 73 calculates the second target load for suppressing vibration caused by road surface input.

[0113] In step S16, the third target load calculation unit 75 of the load control ECU 15 sets the anti-bumping characteristic (see FIG. 14 ) related to the change of the third target load with respect to the change of the stroke position ST of the electromagnetic actuator 13 based on the bumping state evaluation result (e.g., one of low / high / extra high) obtained by the bumping state evaluation unit 69. Figure 5A , Figure 5B ).

[0114] Next, the third target load calculation unit 75 calculates a third target load related to the virtual spring force control for realizing the anti-bumping function based on the stroke position ST of the electromagnetic actuator 13 acquired by the information acquisition unit 41 and the anti-bumping characteristic set as described above.

[0115] In step S17 , 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.

[0116] In step S18, the load control unit 45 of the load control ECU 15 performs load control on the electromagnetic actuator 13 in accordance with the calculation result of step S16, that is, the combined target load. Then, the load control ECU 15 ends a series of processing flows.

[0117] [Operation and Effect of the Electric Suspension Device 11 According to the Embodiment of the Present Invention]

[0118] The electric suspension device 11 based on the first viewpoint includes: an actuator (electromagnetic actuator 13), which is arranged 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 on the sprung state quantity and the driving surface state 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.

[0119] The information acquisition unit 41 further acquires information on the stroke position ST of the electromagnetic actuator 13. In addition, an evaluation unit 61 is provided for evaluating whether the stroke position ST has reached an unusually used region exceeding the ordinary used region based on the information on the stroke position ST.

[0120] The target load calculation unit 43 further calculates a third target load related to the virtual spring force control based on the stroke position ST, and calculates a combined target load by combining the first target load, the second target load, and the third target load, when the evaluation result obtained by the evaluation unit 61 indicates that the stroke position ST has reached the non-usage region. The load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load.

[0121] In the electric suspension device 11 based on the first viewpoint, the target load calculation unit 43 further calculates a third target load related to the virtual spring force control based on the stroke position ST, and calculates a combined target load that combines the first target load, the second target load, and the third target load, when the evaluation result obtained by the evaluation unit 61 indicates that the stroke position ST has reached the non-usage region. The load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load.

[0122] According to the electric suspension device 11 based on the first viewpoint, in addition to the first target load related to the skyhook control and the second target load related to the foresight control, a combined target load is calculated by combining the third target load related to the imaginary spring force control in the anti-bumping direction (the direction toward the neutral position of the stroke), and the combined target load is used to control the load of the electromagnetic actuator 13. Therefore, even if a large input is generated in the shock absorber during the driving of the vehicle 10, the large input can be buffered to maintain a comfortable ride.

[0123] Furthermore, according to the electric suspension device 11 based on the first aspect, in the suspension device including the jump stopper formed of the shock absorbing material, it is possible to achieve an effect of miniaturization of the jump stopper (increase in effective stroke length).

[0124] In addition, the electric suspension device 11 based on the second aspect may adopt the following structure: in the electric suspension device 11 based on the first aspect, the information acquisition unit 41 further acquires information related to the preview image in the forward direction of the vehicle 10, and the evaluation unit 61 performs evaluation related to the virtual road surface input level VR based on the information related to the preview image. When the load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load at the critical moment when it is estimated that the stroke position ST reaches the non-usage area based on the evaluation result obtained by the evaluation unit 61, the load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load.

[0125] In the electric suspension device 11 based on the second viewpoint, the evaluation unit 61 performs an evaluation related to the virtual road surface input level VR based on the information related to the preview image. This evaluation is performed to determine whether the electromagnetic actuator 13 has a risk of falling into a jumping state. When the load control unit 45 performs an evaluation to the effect that the virtual road surface input level VR exceeds the prescribed road surface input threshold value (the first road surface input threshold value VRth1) based on the result of the above evaluation obtained by the evaluation unit 61 (the electromagnetic actuator 13 has a risk of falling into a jumping state), the load control unit 45 performs load control of the electromagnetic actuator 13 using the combined target load at the critical moment when it is estimated that the stroke position ST reaches the non-usage area.

[0126] In addition, regarding the critical moment when the stroke position ST is estimated to reach the non-usage area, when, as an evaluation result involving the hypothetical road surface input level VR, for example, the presence of a hole called a pothole on the driving road surface is identified through preview image analysis, it can be calculated by referring to the distance to the pothole, the vehicle speed of the vehicle 10, etc.

[0127] According to the electric suspension device 11 based on the second viewpoint, when the electromagnetic actuator 13 is in danger of falling into an upward jumping state, the combined target load is used to control the load of the electromagnetic actuator 13 at a critical moment when the stroke position ST is estimated to reach the non-usage area. Therefore, compared with the electric suspension device 11 based on the first viewpoint, even if a large input is generated in the shock absorber during the driving of the vehicle 10, the effect of buffering the large input and maintaining a comfortable ride can be further improved.

[0128] In addition, the electric suspension device 11 based on the third viewpoint can adopt the following structure: in the electric suspension device 11 based on the second viewpoint, when the result of the above evaluation obtained by the evaluation unit 61 is that even if an evaluation is not made to the effect that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1, but an evaluation is made to the effect that the stroke position ST reaches an unusually used area, the load control unit 45 uses the above-mentioned combined target load to perform load control on the electromagnetic actuator 13.

[0129] In the electric suspension device 11 based on the third viewpoint, the load control unit 45 uses the combined target load to control the load of the electromagnetic actuator 13 when the result of the above evaluation obtained by the evaluation unit 61 is that even if there is no evaluation to the effect that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1 (even if there is no risk of the electromagnetic actuator 13 falling into an upward jumping state), but an evaluation to the effect that the stroke position ST has reached an unusually used area is made.

[0130] According to the electric suspension device 11 based on the third viewpoint, even if the electromagnetic actuator 13 does not have the risk of falling into the jumping state but an evaluation is made that the stroke position ST has reached the non-usage area, the combined target load is used to control the load of the electromagnetic actuator 13. Therefore, compared with the electric suspension device 11 based on the second viewpoint, even if a large input is generated in the shock absorber during the travel of the vehicle 10, the effect of buffering the large input and maintaining a comfortable ride can be more reliably obtained.

[0131] In addition, the electric suspension device 11 based on the fourth viewpoint can adopt the following structure: in the electric suspension device 11 based on the second viewpoint, when the target load calculation unit 43 makes an evaluation based on the result of the above-mentioned evaluation obtained by the evaluation unit 61 to the effect that the hypothetical road surface input level VR exceeds the first road surface input threshold value VRth1, the above-mentioned first target load and second target load are not merged, but the third target load involving hypothetical spring force control based on the stroke position ST is used as the merged target load.

[0132] In the electric suspension device 11 based on the fourth viewpoint, when the target load calculation unit 43 makes an evaluation based on the result of the above evaluation obtained by the evaluation unit 61 that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1 (there is a risk that the electromagnetic actuator 13 will fall into an upward jumping state), the above-mentioned first target load and second target load are not merged, but the third target load involving hypothetical spring force control based on the stroke position ST is used as the merged target load.

[0133] According to the electric suspension device 11 based on the fourth viewpoint, when there is a risk that the electromagnetic actuator 13 will fall into a jumping state, the first target load and the second target load are not merged, but the third target load involving the imaginary spring force control based on the stroke position ST is used as the merged target load. Therefore, compared with the electric suspension device 11 based on the second viewpoint, regardless of the calculation accuracy of the first target load or the second target load, even if a large input is generated in the shock absorber during the travel of the vehicle 10, the effect of buffering the large input and maintaining a comfortable ride can be reliably obtained.

[0134] The evaluation related to the virtual road surface input level VR is performed based on the information related to the preview image. The information related to the preview image is affected by interference such as weather, brightness of the road surface to be predicted, and the type of uneven shape, and the granularity of the information changes all the time. Therefore, it can be seen that the evaluation accuracy related to the virtual road surface input level VR will be affected by the above interference and change all the time.

[0135] Therefore, the electric suspension device 11 based on the fifth viewpoint adopts the following structure: in the electric suspension device 11 based on the fourth viewpoint, even if the result of the above-mentioned evaluation obtained by the evaluation unit 61 is a temporary evaluation to the effect that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1 and then the evaluation is overturned, the target load calculation unit 43 does not merge the above-mentioned first target load and the second target load, but continues to perform the calculation using the third target load involving the hypothetical spring force control based on the stroke position ST as the merged target load for a prescribed time from the point in time when the above-mentioned evaluation is overturned.

[0136] In the electric suspension device 11 based on the fifth aspect, even if the target load calculation unit 43 temporarily makes an evaluation based on the evaluation result obtained by the evaluation unit 61 that the virtual road surface input level VR exceeds the first road surface input threshold VRth1 (there is a risk that the electromagnetic actuator 13 will fall into the jumping state) and then the evaluation is overturned, the first target load and the second target load are not combined, but the calculation using the third target load involving the virtual spring force control based on the stroke position ST as the combined target load is continued for a predetermined time from the time when the evaluation is overturned. The length of the predetermined time can be appropriately set in consideration of preventing the electromagnetic actuator 13 from falling into the jumping state.

[0137] According to the electric suspension device 11 based on the fifth viewpoint, when an evaluation is temporarily made that the electromagnetic actuator 13 has a risk of falling into a jumping state and the evaluation is overturned, the first target load and the second target load are not merged, but the calculation using the third target load involving the virtual spring force control based on the stroke position ST as the merged target load is continued for a prescribed time from the point in time when the above evaluation is overturned. Therefore, similar to the electric suspension device 11 based on the fourth viewpoint, regardless of the calculation accuracy of the first target load or the second target load, even if a large input is generated in the shock absorber during the travel of the vehicle 10, the effect of buffering the large input and maintaining a comfortable ride can be reliably obtained.

[0138] In addition, the electric suspension device 11 based on the sixth viewpoint can adopt the following structure: in the electric suspension device 11 based on the second viewpoint or the fourth viewpoint, when the load control unit 45 makes an evaluation based on the result of the above evaluation obtained by the evaluation unit 61 that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1, the load control unit 45 adjusts the critical moment when the stroke position ST is estimated to reach the non-usage area to be earlier in time as the above hypothetical road surface input level VR is higher, and uses the above-mentioned combined target load at the adjusted critical moment to control the load of the electromagnetic actuator 13.

[0139] In the electric suspension device 11 based on the sixth viewpoint, when the load control unit 45 makes an evaluation based on the result of the above evaluation obtained by the evaluation unit 61 that the hypothetical road surface input level VR exceeds the first road surface input threshold VRth1 (there is a risk that the electromagnetic actuator 13 will fall into an upward jumping state), the load control unit 45 adjusts the critical moment when the stroke position ST is estimated to reach the non-usage area to be earlier in time as the above hypothetical road surface input level VR is higher, and uses the above-mentioned combined target load at the adjusted critical moment to control the load of the electromagnetic actuator 13.

[0140] Furthermore, the fact that the critical moment is advanced in time as the virtual road surface input level VR is higher means that the start timing of the virtual spring force control acting in the anti-bumping direction is advanced as the virtual road surface input level VR is higher.

[0141] Here, the problem is how the load control unit 45 performs the adjustment to bring the critical time earlier as the virtual road surface input level VR becomes higher. This will be described below.

[0142] In order to perform the adjustment to advance the critical time in time, the third target load calculation unit 75 (refer to Figure 4 ) Based on the pitch state evaluation result (low / high / extra high) obtained by the pitch state evaluation unit 69 belonging to the evaluation unit 61, the anti-pitch characteristic related to the change of the third target load relative to the change of the stroke position ST of the electromagnetic actuator 13 is set (refer to Figure 5B ).

[0143] Specifically, if Figure 5B As shown, the third target load calculation unit 75 (refer to Figure 4 ) Appropriately switch between the standard anti-bumping characteristics in the case of high bumpiness and the special anti-bumping characteristics in the case of extra-high bumpiness and apply.

[0144] In the case of the pitch state: high, the pitch state evaluation unit 69 (refer to Figure 4 ) Figure 5A As shown, when the stroke position ST of the electromagnetic actuator 13 exceeds the predetermined standard critical threshold value STct0, it is evaluated that the stroke position ST has reached the non-usage region.

[0145] On the other hand, in the case of the bumping state: extremely high, the bumping state evaluation unit 69 (refer to Figure 4 ) Figure 5B As shown, when the stroke position ST of the electromagnetic actuator 13 exceeds the predetermined special critical threshold value STct1, it is evaluated that the stroke position ST has reached the non-usage region.

[0146] In addition, the third target load calculation unit 75 applies the following when the bump state is high: Figure 5B The third target load for the stroke position ST is calculated based on the standard anti-bumping characteristics shown.

[0147] On the other hand, the third target load calculation unit 75 applies the following when the turbulence state is: extremely high: Figure 5B The special anti-bumping characteristics shown are used to calculate the third target load for the stroke position ST.

[0148] In short, the load control unit 45 appropriately switches and applies the plurality of anti-bumping characteristics (standard anti-bumping characteristics, special anti-bumping characteristics) prepared in advance in the third target load calculation unit 75 according to the bumping state evaluation result obtained by the bumping state evaluation unit 69. Thus, the critical moment is adjusted to be earlier in time as the virtual road surface input level VR is higher.

[0149] According to the electric suspension device 11 based on the sixth viewpoint, when an evaluation is made that the electromagnetic actuator 13 has a risk of falling into a jumping state, regarding the critical moment when the stroke position ST is estimated to reach the non-usage area, the higher the hypothetical road input level VR is, the earlier the critical moment (the starting period of the hypothetical spring force control acting in the anti-bumping direction) is adjusted in time, and the load of the electromagnetic actuator 13 is controlled using the above-mentioned combined target load at the adjusted critical moment. Therefore, compared with the electric suspension device 11 based on the second viewpoint or the fourth viewpoint, even if a large input is generated in the shock absorber during the driving of the vehicle 10, for example, when an excessive input is generated, appropriate stroke management corresponding to the input size, such as increasing the stroke amount of the electromagnetic actuator 13, can be achieved.

[0150] [Other implementation methods]

[0151] The multiple embodiments described above show examples of the embodiment 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.

[0152] 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), but the present invention is not limited to this example. A structure in which a total of two electromagnetic actuators 13 are arranged on either the front wheel or the rear wheel may also be adopted.

[0153] In the description of the electric suspension device 11 according to the embodiment of the present invention, the load control unit 45 is mentioned to independently control 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 in the four wheels.

[0154] 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.

[0155] Finally, in the description of the electric suspension device 11 according to the embodiment of the present invention, the ball screw method is 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 that acquires information on a sprung state quantity and a running road state of the vehicle; a target load calculation unit that calculates a first target load related to skyhook control based on the sprung state amount and calculates a second target load related to look-ahead control based on the running road surface state; and a load control unit that performs load control of 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 stroke position of the actuator, further comprising an evaluation unit for evaluating whether the travel position has reached an unused area beyond a commonly used area based on information related to the travel position, The target load calculation unit further calculates a third target load related to virtual spring force control based on the stroke position, and calculates a combined target load by combining the first target load, the second target load and the third target load, when the evaluation result obtained by the evaluation unit indicates that the stroke position has reached the non-usage region. The load control unit performs load control of the actuator using the combined target load.

2. The electric suspension device according to claim 1, characterized in that: The information acquisition unit further acquires information related to a preview image ahead of the vehicle in the traveling direction. The evaluation unit performs evaluation related to the virtual road surface input level based on information related to the preview image. When the load control unit makes an evaluation based on the evaluation result obtained by the evaluation unit that the hypothetical road surface input level exceeds a prescribed road surface input threshold, the load control unit performs load control of the actuator using the combined target load at a critical moment when it is estimated that the stroke position reaches the non-usage area.

3. The electric suspension device according to claim 2, characterized in that: The load control unit performs load control of the actuator using the combined target load when an evaluation result based on the evaluation unit indicates that the stroke position has reached the non-usage area even though the evaluation result based on the evaluation unit indicates that the hypothetical road surface input level exceeds the road surface input threshold.

4. The electric suspension device according to claim 2, characterized in that: When the target load calculation unit makes an evaluation based on the evaluation result obtained by the evaluation unit to the effect that the hypothetical road surface input level exceeds the road surface input threshold value, the target load calculation unit does not combine the first target load and the second target load but instead performs a calculation using the third target load involving hypothetical spring force control based on the stroke position as the combined target load.

5. The electric suspension device according to claim 4, characterized in that: Even if the target load calculation unit temporarily makes an evaluation that the hypothetical road surface input level exceeds the road surface input threshold value based on the evaluation result obtained by the evaluation unit and then overturns the evaluation, the target load calculation unit does not merge the first target load and the second target load, but continues to perform the calculation using the third target load involving hypothetical spring force control based on the stroke position as the merged target load for a prescribed time from the point in time when the evaluation is overturned.

6. The electric suspension device according to claim 2 or 4, characterized in that: When the load control unit makes an evaluation based on the evaluation result obtained by the evaluation unit that the hypothetical road surface input level exceeds the road surface input threshold, the load control unit adjusts the critical time when the stroke position is estimated to reach the non-usage area to be earlier in time as the hypothetical road surface input level is higher. The load control of the actuator is performed using the combined target load at the adjusted critical time.

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