Electrically powered suspension device

Abstract

Provided is an electric suspension device that appropriately derives a target load for attenuating vibrations of a vehicle body in consideration of the handling stability and ride comfort of the vehicle. The electric suspension device is provided with an electromagnetic actuator that generates a load for attenuating vibrations of a vehicle body of a vehicle; an information acquisition unit that acquires information on a stroke speed of the electromagnetic actuator and a sprung speed of the vehicle; a target load calculation unit that performs calculation of a combined target load that combines an attenuation target load and an extension / contraction target load; and a load control unit that performs load control of the electromagnetic actuator using the combined target load. The target load calculation unit is provided with a determination unit that performs determination as to whether or not a combined target current involved in the combined target load should be limited, and a target current correction unit that, in the case where the determination unit determines that the combined target current should be limited, maintains an attenuation target current involved in the attenuation target load, and on the other hand performs correction of limiting an extension / contraction target current involved in the extension / contraction target load.

Description

Technical Field

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

[0002] The applicant of the present application has disclosed an invention of an electric suspension device including an actuator provided between a vehicle body and wheels and generating a load for attenuating vibrations of the vehicle body (see, for example, Patent Document 1).

[0003] The electric suspension device disclosed in Patent Document 1 includes an actuator having an electric motor that generates driving force for damping and telescopic movements; a damping target load setting unit that sets a damping target load; a telescopic target load setting unit that sets a telescopic target load; and a drive control unit that controls the drive of the electric motor using target driving forces based on the damping and telescopic target loads. The drive control unit performs drive control to limit the motor current so that the accumulated motor current does not exceed a current limit threshold (the sum of the damping current limit threshold and the telescopic current limit threshold). The damping current limit threshold and the telescopic current limit threshold are independently set based on the priority between vehicle ride comfort and handling stability.

[0004] In the electric suspension device of Patent Document 1, in an abnormal situation where the electric motor is in an overheated state, for example, when there are frequent requests for the generation of damping force and extension force involving the electric suspension device 11 while the vehicle 10 is traveling on a bumpy unpaved road, damping control mainly related to handling stability is given priority over extension control mainly related to the ride comfort of the vehicle 10 (see paragraphs 0114 and 0115 of Patent Document 1).

[0005] According to the electric suspension device of Patent Document 1, even when the electric motor included in the electromagnetic actuator is in an overheated state, vehicle vibration can be controlled without disrupting vehicle behavior and minimizing the loss of vehicle ride comfort.

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-172227 Summary of the Invention

[0007] However, target loads derived for the purpose of damping vehicle body vibrations can be roughly classified into two systems: a damping target load derived based on the stroke speed of the actuator and a telescoping target load derived based on the sprung state quantity of the vehicle.

[0008] The damping target load is mainly related to the unsprung vibration control and plays an important role in ensuring the vehicle's handling stability. In addition, the telescopic target load is mainly related to the sprung vibration control and plays an important role in improving the vehicle's ride comfort.

[0009] On the other hand, the power supply capacity of the vehicle's power supply is limited, so how to properly allocate the limited power supply capacity becomes a problem.

[0010] Regarding this aspect, the electric suspension device of Patent Document 1 neither describes nor suggests considering the distribution of the damping target load and the telescopic target load when deriving the target load. Therefore, there remains room for improvement in appropriately deriving the target load for damping vehicle body vibrations while taking into account vehicle handling stability and ride comfort.

[0011] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide an electric suspension device capable of appropriately deriving a target load for attenuating vehicle body vibrations while taking into account the vehicle's handling stability and ride comfort.

[0012] In order to achieve the above-mentioned object, the electric suspension device of the present invention (1) comprises: an actuator provided between a vehicle body and a wheel, generating a load for attenuating vibration of the vehicle body; an information acquisition unit, acquiring information on a stroke speed of the actuator and a sprung state quantity of the vehicle; a target load calculation unit, calculating an attenuation target load involved in unsprung vibration damping control based on the stroke speed, and calculating a telescopic target load involved in sprung vibration damping control based on the sprung state quantity, and performing a calculation of a combined target load by combining the attenuation target load and the telescopic target load; and a load control unit, which uses the combined target load to calculate a combined target load. The load control of the above-mentioned actuator is performed, and the most important feature of the electric suspension device is that the above-mentioned target load calculation unit includes: a judgment unit, which judges whether the combined target current involved in the above-mentioned combined target load should be limited; and a target current correction unit, which maintains the attenuation target current involved in the above-mentioned attenuation target load when the above-mentioned judgment unit judges that the above-mentioned combined target current should be limited, and on the other hand, corrects the telescopic target current involved in the above-mentioned telescopic target load to limit the above-mentioned telescopic target load, and calculates the above-mentioned combined target current by combining the above-mentioned attenuation target current and the telescopic target current corrected by the above-mentioned target current correction unit.

[0013] Effects of the Invention

[0014] According to the present invention, it is possible to appropriately derive a target load for damping the vibration of the vehicle body while taking into account the steering stability and ride comfort of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram showing the overall configuration of an electric suspension device according to an embodiment of the present invention.

[0016] 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.

[0017] 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.

[0018] Figure 4A 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.

[0019] Figure 4B This is an explanatory diagram of a damping target load graph that conceptually shows the relationship between the damping target load that changes in accordance with changes in the stroke speed.

[0020] Figure 4C This is an explanatory diagram of a telescopic target load map that conceptually shows the relationship between the telescopic target load that changes in accordance with changes in sprung velocity.

[0021] Figure 5A This is a flowchart for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0022] Figure 5B This is a flowchart for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0023] Figure 6 This is a timing chart for explaining the operation of the electric suspension device according to the embodiment of the present invention.

[0024] Description of Reference Numerals

[0025] 10 vehicles

[0026] 11 Electric suspension

[0027] 13 Electromagnetic actuator (actuator)

[0028] 15 Load Control ECU

[0029] 31 Electric Motor

[0030] 41 Information Acquisition Department

[0031] 43 Target load calculation unit

[0032] 45 Load Control Unit

[0033] 61 Attenuation target load calculation unit

[0034] 63 Telescopic target load calculation unit

[0035] 65 Merger Department

[0036] 71 Accumulated value calculation unit

[0037] 73 Judgment Department

[0038] 75 Target current correction unit

[0039] 77 Zero Point

[0040] TC scaling target current

[0041] ACC Accumulated value of expansion / contraction target current

[0042] ACCth Current accumulation threshold DETAILED DESCRIPTION

[0043] Hereinafter, the electric suspension device 11 according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings as appropriate.

[0044] In the drawings shown below, components with common functions are denoted by common reference numerals. In this case, as a principle, repeated descriptions are omitted. In addition, the sizes and shapes of components may be distorted or exaggerated for ease of description.

[0045] [Basic Structure Common to the Electric Suspension Devices 11 According to the Embodiments of the Present Invention]

[0046] 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.

[0047] Figure 1 This 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 .

[0048] The electric suspension device 11 according to the embodiment of the present invention is as follows Figure 1 As shown, the vehicle 10 is provided with a plurality of electromagnetic actuators 13 and a load control ECU 15 provided for each wheel of the vehicle (sometimes referred to as the vehicle itself). 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 ) for supplying load control power from the load control ECU 15 to the plurality of electromagnetic actuators 13. Figure 1 solid line), and an electric motor 31 for transmitting power from the plurality of electromagnetic actuators 13 to the load control ECU 15 (refer to Figure 2 ) of the load control signal line 16 (refer to Figure 1 are connected to each other by dashed lines).

[0049] In this embodiment, a total of four electromagnetic actuators 13 are arranged 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 arranged for each wheel are independently load-controlled according to the extension and retraction operation of each wheel.

[0050] 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 .

[0051] The electromagnetic actuator 13 is as follows Figure 2 As shown, the structure 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 .

[0052] 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.

[0053] In order to transmit the rotational driving force to the ball screw shaft 23, as shown in FIG. Figure 2 As 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. 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.

[0054] 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.

[0055] In addition, in this embodiment, if Figure 2As shown, the axial dimension of the electromagnetic actuator 13 is shortened by adopting a layout in which the motor shaft 31a of the electric motor 31 and the ball screw shaft 23 are arranged approximately parallel to each other and connected thereto. However, a layout in which the motor shaft 31a of the electric motor 31 and the ball screw shaft 23 are coaxially arranged and connected thereto may also be adopted.

[0056] 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. This connecting portion 39 is connected and fixed to an unsprung component (not shown) (such as a lower arm on the wheel side, a steering knuckle, etc.). Meanwhile, the upper end portion 29a of the inner tube 29 is connected and fixed to a sprung component (not shown) (such as a strut tower on the vehicle body side).

[0057] In short, the electromagnetic actuator 13 is provided in parallel with a spring member (suspension) (not shown) mounted between the sprung member (vehicle body) and the unsprung member (wheel with tire mounted thereon, etc.) of the vehicle 10. The electromagnetic actuator 13 functions as a virtual damper to buffer the expansion and contraction force of the spring member (suspension).

[0058] The electromagnetic actuator 13 constructed as described above operates as follows. For example, consider a case 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 descend as a whole 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 conforms to 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.

[0059] 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.

[0060] [Internal Structure of Load Control ECU 15]

[0061] Next, refer to Figure 3 The configuration 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 will be described.

[0062] 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.

[0063] [Electric Suspension Device 11 According to an Embodiment of the Present Invention]

[0064] The load control ECU 15 of the electric suspension device 11 according to the embodiment of the present invention includes a microcomputer that performs various calculations. The load control ECU 15 has a load control function, such as Figure 3 As shown, based on the rotation angle signal including the stroke position 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., the load control of each of the multiple electromagnetic actuators 13 is performed, thereby generating the load involved in the attenuation action and the extension and contraction action of the electromagnetic actuator 13.

[0065] In order to realize such load control function, the load control ECU 15 Figure 3 As shown, the system includes an information acquisition unit 41 , a target load calculation unit 43 , and a load control unit 45 .

[0066] like Figure 3 As shown, the information acquisition unit 41 acquires the preview image and vehicle height information as time series information on the vehicle speed of the vehicle 10 , the stroke position of the electromagnetic actuator 13 , and the road surface state in the traveling direction of the vehicle 10 .

[0067] The information on the vehicle speed of the host vehicle 10 may be acquired by the vehicle speed sensor 51 that detects the vehicle speed of the host vehicle 10 .

[0068] The stroke position information of the electromagnetic actuator 13 may be acquired, for example, from the rotation angle signal of the electric motor 31 detected by the resolver 37. The information acquisition unit 41 acquires information on the stroke speed SV by temporally differentiating the time series information on the stroke position.

[0069] On the other hand, the preview image information can be acquired by, for example, a laser, radar, or other external sensor other than the camera 53 provided on the vehicle 10. Furthermore, the vehicle height information can be acquired by, for example, the vehicle height sensor 55 that detects the vehicle height of the vehicle 10.

[0070] The information acquisition unit 41 acquires time-series information on the sprung acceleration and the unsprung acceleration. The sprung acceleration information can be acquired based on the detection values ​​of a sprung acceleration sensor 57 provided on a sprung member (the vehicle body) of the vehicle 10. Furthermore, the information acquisition unit 41 acquires information on the sprung velocity BV by integrating the time-series information on the sprung acceleration over time.

[0071] The information on the unsprung acceleration may be acquired based on the detection value of the unsprung acceleration sensor 59 provided on an unsprung member (wheel, etc.) of the vehicle 10 .

[0072] The vehicle speed, stroke position of the electromagnetic actuator 13 , stroke speed SV, preview image, sprung acceleration, sprung speed BV, unsprung acceleration, vehicle height, and information related to the motor current of the electric motor 31 acquired by the information acquisition unit 41 are sent to the target load calculation unit 43 .

[0073] The target load calculation unit 43 has a function of calculating the attenuation target load and the extension target load related to the electromagnetic actuator 13 based on the various information obtained by the information acquisition unit 41 , and obtaining a combined target load by combining them through calculation.

[0074] In practice, the target load calculation unit 43 includes a damping target load calculation unit 61 for calculating a damping target load associated with unsprung vibration damping control, a telescoping target load calculation unit 63 for calculating a telescoping target load associated with sprung vibration damping control, and a merging unit 65. The structures of the damping target load calculation unit 61, the telescoping target load calculation unit 63, and the merging unit 65 will be described in detail later.

[0075] The load control unit 45 controls the drive of the electric motor 31 included in each of the plurality of electromagnetic actuators 13 so that the motor current of the electric motor 31 follows the combined target current based on the combined target current associated with the combined target load calculated by the target load calculation unit 43. Load control of each electric motor 31 is performed independently in each of the plurality of electromagnetic actuators 13.

[0076] [Main Configuration of the Load Control ECU 15 Included in the Electric Suspension Device 11]

[0077] Next, refer to Figure 4A 、 Figure 4B 、 Figure 4C 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.

[0078] Figure 4A 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 4B This is an explanatory diagram of a damping target load map that conceptually shows the relationship between the damping target load that changes in accordance with changes in the stroke speed SV. Figure 4C This is an explanatory diagram of a telescopic target load map that conceptually shows the relationship between the telescopic target load that changes in accordance with changes in the sprung velocity BV.

[0079] The load control ECU 15 included in the electric suspension device 11 is as follows: Figure 4A As shown in FIG. 4 , a target load calculation unit 43 is provided. The target load calculation unit 43 is as follows: Figure 3 and Figure 4AAs shown, the system includes a decay target load calculation unit 61 , a telescoping target load calculation unit 63 , and a merging unit 65 .

[0080] The damping target load calculation unit 61 calculates the stroke speed SV based on the information acquired via the information acquisition unit 41 and the damping target load table 67 (see Figure 4B ), calculate the value of the attenuation target load that matches the stroke speed SV. Figure 4B The damping target load map 67 shown conceptually shows the relationship between the damping target load and the change in stroke speed SV (damping target load characteristics). Furthermore, the damping target load map 67 actually stores the target value of the damping force control current (damping target current value) as a value corresponding to the damping target load.

[0081] The change range (domain) of the stroke speed SV involved in the attenuation target load chart 67 is as follows: Figure 4B As shown, it consists of a normal range SV1 and an abnormal range SV2. The normal range SV1 is a speed range where the travel speed SV is below the normal speed threshold SVth (|SV-SVth|=<0). In normal driving situations, the travel speed SV generally falls within the normal range SV1.

[0082] The normal speed threshold SVth may be set to an appropriate value by evaluating the probability density function of the travel speed SV through experiments, simulations, etc., with reference to the evaluation results, and taking into account that the distribution ratio of the travel speed SV appearing in the normal area SV1 and the non-normal area SV2 satisfies a predetermined distribution ratio.

[0083] The attenuation target load characteristics of the attenuation target load diagram 67 under the common area SV1 are as follows: Figure 4B As shown, the damping target load toward the contraction side increases approximately linearly as the stroke speed SV increases toward the extension side, while the damping target load toward the extension side increases approximately linearly as the stroke speed SV increases toward the contraction side. This characteristic is the damping characteristic of conventional hydraulic shock absorbers. Furthermore, when the stroke speed SV is zero, the corresponding damping target load is also zero.

[0084] In addition, the attenuation target load characteristics related to the attenuation target load graph 67 in the non-use area SV2 are as follows: Figure 4B As shown, similar to the attenuation target load characteristics involved in the attenuation target load chart 67 under the commonly used area SV1, it has the characteristic that the greater the stroke speed SV points to the extension side, the attenuation target load pointing to the contraction side becomes larger in a roughly linear manner, and on the other hand, the greater the stroke speed SV points to the contraction side, the attenuation target load pointing to the extension side becomes larger in a roughly linear manner.

[0085] However, the slope of the attenuation target load characteristic related to the attenuation target load graph 67 in the non-use area SV2 is as follows: Figure 4B As shown, a characteristic with a gentle slope is set compared to the slope of the decay target load characteristic according to the decay target load table 67 in the normal range SV1.

[0086] The decay target load (decay target current) calculated by the decay target load calculation unit 61 is sent to the merging unit 65 .

[0087] The telescopic target load calculation unit 63 calculates the telescopic target load based on the information of the sprung velocity BV acquired via the information acquisition unit 41 and the telescopic target load table 69 (see Figure 4C ), and calculate the value of the telescopic target load that matches the sprung velocity BV. Figure 4C The telescopic target load map 69 conceptually illustrates the relationship between the telescopic target load and changes in sprung velocity BV (telescopic target load characteristics). Furthermore, the telescopic target load map 69 actually stores a target value for the telescopic force control current (telescopic target current TC) as a value corresponding to the telescopic target load.

[0088] The telescopic target load characteristics involved in the telescopic target load chart 69 are as follows: Figure 4C As shown, the target telescopic load toward the contraction side increases linearly as the sprung velocity BV toward the extension side increases, and conversely, the target telescopic load toward the extension side increases linearly as the sprung velocity BV toward the contraction side increases.

[0089] The telescopic target load characteristics related to the telescopic target load table 69 may be obtained by performing experiments or simulations to obtain telescopic target loads that match the sprung velocity BV in order to maintain the posture of the vehicle 10 at a predetermined state, and setting appropriate characteristic values ​​obtained therein.

[0090] The telescopic target load calculation unit 63 is configured to include an integrated value calculation unit 71 , a determination unit 73 , and a target current correction unit 75 in order to calculate a telescopic target load value that matches the sprung velocity BV.

[0091] The integrated value calculation unit 71 calculates the expansion target current TC related to the expansion target load at the zero-crossing point 77 (see Figure 6The telescopic target current TC at times t2, t5, and t7 is the cumulative value ACC of the telescopic target current TC during the start period. The cumulative value calculator 71 monitors the evolution of the telescopic target current TC and extracts the time when the sign of the telescopic target current TC reverses (positive to negative / negative to positive) as a zero-crossing point 77 of the telescopic target current TC. Upon extracting the zero-crossing point 77 of the telescopic target current TC, the cumulative value calculator 71 initializes the cumulative value ACC of the telescopic target current TC to zero. The cumulative value calculator 71 then accumulates the telescopic target current TC until the next zero-crossing point 77 is extracted.

[0092] The integrated value ACC of the expansion / contraction target current TC calculated by the integrated value calculation unit 71 is sent to the determination unit 73 .

[0093] Determination unit 73 determines whether the combined target current associated with the combined target load should be limited. Specifically, determination unit 73 determines whether the integrated value ACC of the telescopic target current TC calculated by integrated value calculation unit 71 exceeds a predetermined current integration threshold ACCth. If the result of this determination is that the integrated value ACC of the telescopic target current TC exceeds the current integration threshold ACCth, determination is made that the combined target current should be limited.

[0094] The determination result of whether the combined target current should be limited, made by the determination unit 73 , is sent to the target current correction unit 75 .

[0095] When the determination unit 73 determines that the combined target current should be limited, the target current correction unit 75 corrects the expansion and contraction target current TC by multiplying the expansion and contraction target current TC by a predetermined correction ratio RT to thereby limit the expansion and contraction target current TC. The correction ratio RT has the following characteristics: its initial value is set to a value of 1 or less, and its value linearly decreases with the passage of time while the cumulative value ACC of the expansion and contraction target current TC exceeds the current cumulative threshold ACCth and increases (see Figure 6 The linear decreasing characteristics of the correction ratio RT at time t3 to t4).

[0096] However, even if the determination unit 73 determines that the combined target current should be limited, the target current correction unit 75 cancels the correction of the limited telescopic target current TC if the corrected telescopic target current TC1 is lower than the pre-corrected telescopic target current TC0. Furthermore, when there is no need to distinguish between the pre-correction and post-correction labels for the telescopic target currents, a common label "TC" is used.

[0097] The telescopic target load (telescopic target current TC) calculated by the telescopic target load calculation unit 63 is sent to the merging unit 65 .

[0098] The combining unit 65 combines the decay target load (decay target current) calculated by the decay target load calculation unit 61 and the telescopic target load (telescopic target current TC) calculated by the telescopic target load calculation unit 63 , and outputs the combined target load (decay target current).

[0099] The combined target load (attenuation target current) combined by the combining unit 65 is sent to the load control unit 45 .

[0100] [Operation of the Electric Suspension Device 11]

[0101] Next, refer to Figure 5A 、 Figure 5B The operation of the electric suspension device 11 according to the embodiment of the present invention will be described. Figure 5A This is a flowchart for explaining the operation of the electric suspension device 11 according to the embodiment of the present invention. Figure 5B 1 is a flowchart showing a calculation process of the telescopic target load (telescopic target current TC).

[0102] exist Figure 5A In step S11 shown, the information acquisition unit 41 of the load control ECU 15 acquires various information including the vehicle speed of the host vehicle 10 , the stroke speed SV and the sprung velocity BV of the electromagnetic actuator 13 , and the motor current of the electric motor 31 .

[0103] In step S12, the damping target load calculation unit 61 calculates the stroke speed SV based on the information of the stroke speed SV acquired via the information acquisition unit 41 and the damping target load table 67 (see Figure 4B ), calculate the value of the attenuation target load (attenuation target current) that matches the stroke speed SV.

[0104] Then, in Figure 5B In the subroutine Sub shown, the steps of calculating the telescopic target load are performed in sequence. Figure 5A Part of the main program is shown.

[0105] exist Figure 5B In step S21 of the subroutine Sub shown in FIG. 1 , the telescopic target load calculation unit 63 calculates the telescopic target load based on the information of the sprung velocity BV acquired via the information acquisition unit 41 and the telescopic target load table 69 (see FIG. 1 ). Figure 4C ), and calculate the value of the telescopic target load that matches the sprung velocity BV.

[0106] In step S22 of the subroutine Sub, the telescopic target load calculation unit 63 converts the telescopic target load calculated in step S21 into the telescopic target current TC. This conversion is performed by referring to a conversion table (not shown) for converting the telescopic target load into the telescopic target current TC.

[0107] In step S23 of the subroutine Sub, the integrated value calculation unit 71 of the telescopic target load calculation unit 63 monitors the change of the telescopic target current TC.

[0108] When the sign of the expansion / contraction target current TC reverses (positive to negative / negative to positive: zero crossing) through this monitoring, the integrated value calculation unit 71 extracts this time point as the zero crossing point 77 of the expansion / contraction target current TC (Yes in step S23), and the processing flow proceeds to the next step S24.

[0109] On the other hand, if the sign of the expansion / contraction target current TC does not invert (positive→negative / negative→positive: zero crossing) through monitoring in step S23 , the integrated value calculation unit 71 jumps the processing flow to step S25 .

[0110] In step S24 of the subroutine Sub, the integrated value calculation unit 71 of the telescopic target load calculation unit 63 initializes the integrated value ACC of the telescopic target current TC to zero.

[0111] In step S25 of the subroutine Sub, the integrated value calculation unit 71 of the telescopic target load calculation unit 63 calculates the integrated value ACC of the current telescopic target current TC by adding the current telescopic target current TC to the integrated value ACC of the previous telescopic target current TC (ACC=ACC+TC).

[0112] In step S26 of the subroutine Sub, the determination unit 73 of the telescopic target load calculation unit 63 determines whether the integrated value ACC of the current telescopic target current TC exceeds a predetermined current integration threshold value ACCth.

[0113] If the result of step S26 indicates that the integrated value ACC of the current telescopic target current TC does not exceed the current integration threshold ACCth (the combined target current should not be limited yet) (No in step S26 ), the telescopic target load calculation unit 63 advances the processing flow to the next step S27 .

[0114] On the other hand, if the result of determination in step S26 is that the integrated value ACC of the current telescopic target current TC exceeds the current integration threshold ACCth (the combined target current should be limited) (YES in step S26 ), the telescopic target load calculation unit 63 jumps the processing flow to step S28 .

[0115] If it is determined in step S26 of the subroutine Sub that the combined target current should not be limited, in step S27 the target current correction unit 75 of the telescopic target load calculation unit 63 sets 1 as the correction ratio RT (RT=1).

[0116] On the other hand, if it is determined in step S26 of the subroutine Sub that the combined target current should be limited, in step S28 the target current correction unit 75 of the telescopic target load calculation unit 63 sets an appropriate value as the correction ratio RT.

[0117] Specifically, the correction ratio RT has the following characteristics: its initial value is set to a value less than 1 (in Figure 6 In the example shown, the initial value of the correction ratio RT is 1), and in the interval where the integrated value ACC of the telescopic target current TC exceeds the current integrated threshold value ACCth and increases, the value decreases linearly with the passage of time (see Figure 6 The linear decreasing characteristics of the correction ratio RT at time t3 to t4).

[0118] In step S29 of the subroutine Sub, the target current correction unit 75 of the telescopic target load calculation unit 63 corrects the value of the telescopic target current TC0 before the current correction by multiplying the correction ratio RT set in step S27 or S28. This results in the target current correction unit 75 obtaining the value of the telescopic target current TC1 after the current correction. However, if the correction ratio RT is set to 1, the value of the telescopic target current TC0 before the current correction is the same as the value of the telescopic target current TC1 after the current correction.

[0119] When the processing of step S29 of the subroutine Sub is completed, the telescopic target load calculation unit 63 returns the processing flow to the main routine.

[0120] Returning to the main program to continue the explanation, in step S13, the merging unit 65 calculates the merged target load (attenuation target current) by adding the attenuation target load (attenuation target current) calculated by the attenuation target load calculation unit 61 and the telescopic target load (the value of the telescopic target current TC1 after this correction) calculated by the target load calculation unit 63.

[0121] The combined target load (attenuation target current) combined by the combining unit 65 is sent to the load control unit 45 .

[0122] In step S14, the load control unit 45 of the load control ECU 15 performs load control of the electromagnetic actuator 13 according to the calculation result of step S13, that is, the combined target load. Then, the load control ECU 15 ends the series of processing flows.

[0123] [Sequence Operation of the Electric Suspension Device 11]

[0124] Next, refer to Figure 6 The sequential operation of the electric suspension device 11 according to the embodiment of the present invention will be described. Figure 6 This is a timing chart for explaining the sequential operation of the electric suspension device 11 according to the embodiment of the present invention.

[0125] exist Figure 6 In the interval between time t1 and t2 shown, the value of the telescopic target current TC is relatively small. Therefore, the integrated value ACC of the telescopic target current TC does not exceed the current integration threshold ACCth. During this interval, the correction ratio RT remains at 1. As a result, no limit correction is substantially performed on the telescopic target current TC. This is because even if the value of the telescopic target current TC before correction is multiplied by the correction ratio RT (RT = 1), the values ​​of the telescopic target current TC before and after correction remain unchanged.

[0126] In the period from time t2 to just before time t5 , the value of the expansion / contraction target current TC shows a characteristic in which the value temporarily increases to the negative side and then returns to zero.

[0127] At time t2 in the interval from time t2 to just before time t5, the sign of the expansion / contraction target current TC reverses from positive to negative (zero crossing). Therefore, at time t2, the integrated value ACC of the expansion / contraction target current TC is initialized to zero.

[0128] Here, a positive sign of the telescopic target current TC indicates that the electric motor 31 included in the electromagnetic actuator 13 is operating in a power running (power consumption) state. On the other hand, a negative sign of the telescopic target current TC indicates that the electric motor 31 included in the electromagnetic actuator 13 is operating in a regenerative (power generation) state.

[0129] During the interval between time t2 and t3, the value of the expansion / contraction target current TC increases to the negative side. As a result, at time t3, the integrated value ACC of the expansion / contraction target current TC exceeds the current integration threshold ACCth. However, at this time t3, the correction ratio RT remains at 1 (RT = 1).

[0130] In the interval of time t3-t4, the characteristic is shown in which the value of the expansion target current TC temporarily increases on the negative side and then points to the zero side. In this interval, the accumulated value ACC of the expansion target current TC slowly increases in a state where it exceeds the current accumulation threshold value ACCth. In addition, in this interval, the characteristic is shown in which the value of the correction ratio RT linearly decreases with the passage of time.

[0131] At time t4 in the interval of time t3-t4, the value (absolute value) of the expansion target current TC0 before this correction is lower than the value (absolute value) of the expansion target current TC1 after the previous (last) correction. In this case, in the interval after time t4 in the interval of time t2 to near t5, the value of the correction ratio RT is reset to 1 (RT = 1).

[0132] As a result, even in the case where the judgment is made by the judging section 73 that the merging target current should be limited, the correction of the expansion target current TC is released from the limitation. In summary, in the interval of time t4 to near t5, the value of the expansion target current TC before the correction is directly used.

[0133] In the interval of time t5-t7, the characteristic is shown in which the value of the expansion target current TC temporarily increases on the positive side and then returns to zero.

[0134] At time t5 in the interval of time t5-t7, the sign of the expansion target current TC is reversed to negative → positive (zero-crossing). Therefore, at this time t5, the accumulated value ACC of the expansion target current TC is initialized to zero.

[0135] In the interval of time t5-t6, the value of the expansion target current TC increases on the positive side. As a result, at time t6, the accumulated value ACC of the expansion target current TC exceeds the current accumulation threshold value ACCth. However, at this time t6, the value of the correction ratio RT is maintained at 1 (RT = 1).

[0136] In the interval of time t6-t7, the characteristic is shown in which the value of the expansion target current TC returns to zero after maintaining the value of the expansion target current TC at time t6. In this interval, the accumulated value ACC of the expansion target current TC slowly increases in a state where it exceeds the current accumulation threshold value ACCth. In addition, in this interval, the characteristic is shown in which the value of the correction ratio RT linearly decreases with the passage of time.

[0137] Therefore, in the interval of time t6-t7, the corrected value is adopted as the value of the expansion target current TC.

[0138] At time t7 in the time interval from time t6 to time t7, the sign of the expansion target current TC converges to negative → zero (zero-crossing). Therefore, at this time t7, the accumulated value ACC of the expansion target current TC is initialized to zero. Also, at this time t7, the value of the correction ratio RT is reset to 1 (RT = 1).

[0139] Effects of the electric suspension device 11 according to the embodiment of the present application

[0140] The electric suspension device 11 according to the first aspect includes: an actuator (electromagnetic actuator 13) provided between a vehicle body and a wheel of a vehicle 10, which generates a load for attenuating a vibration of the vehicle body; an information acquisition unit 41 which acquires information of a stroke speed SV of the electromagnetic actuator 13 and a sprung state quantity (sprung speed BV) of the vehicle 10; a target load calculation unit 43 which calculates an attenuation target load involved in unsprung vibration control based on the stroke speed SV, and calculates an expansion target load involved in sprung vibration control based on the sprung speed BV, and performs calculation of a combined target load which combines the attenuation target load and the expansion target load; and a load control unit 45 which performs load control of the electromagnetic actuator 13 using the combined target load.

[0141] The target load calculation unit 43 includes: a determination unit 73 which performs determination as to whether or not the combined target current involved in the combined target load should be limited; and a target current correction unit 75 which, in a case where the determination unit 73 makes a determination that the combined target current should be limited, maintains an attenuation target current involved in the attenuation target load, and on the other hand, performs correction of limiting an expansion target current TC involved in the expansion target load, and obtains the combined target current by combining the attenuation target current and the expansion target current TC which is corrected based on the target current correction unit 75.

[0142] In the target load calculation unit 43 included in the electric suspension device 11 according to the first aspect, the determination unit 73 performs determination as to whether or not the combined target current involved in the combined target load should be limited. The target current correction unit 75, in a case where the determination unit 73 makes a determination that the combined target current should be limited, maintains an attenuation target current involved in the attenuation target load which relates to handling stability of the vehicle, and on the other hand, performs correction of limiting an expansion target current TC involved in the expansion target load which relates to ride comfort of the vehicle. Then, the target load calculation unit 43 obtains the combined target current by combining the attenuation target current and the expansion target current TC which is corrected based on the target current correction unit 75.

[0143] According to the electric suspension device 11 based on the first viewpoint, in a case where the judgment that the merging target current should be limited is made, the attenuation target current involved in the attenuation target load related to the handling stability of the vehicle is maintained, on the other hand, the correction of the extension target current TC involved in the extension target load related to the ride comfort of the vehicle is performed, the merging target current is found by merging the attenuation target current and the corrected extension target current TC, and the load control of the electromagnetic actuator 13 is performed using the merging target load, and thus the target load for attenuating the vibration of the vehicle body can be appropriately derived while taking into account the handling stability and the ride comfort of the vehicle. As a result, even during the travel of the vehicle on an uneven road, the vibration control of the vehicle can be performed without disturbing the behavior of the vehicle and without impairing the ride comfort of the vehicle as much as possible.

[0144] In addition, the electric suspension device 11 based on the second viewpoint can adopt the following structure: in the electric suspension device 11 based on the first viewpoint, the target load operation section 43 further has a cumulative value calculation section 71 that calculates a cumulative value ACC of the extension target current TC starting from the zero-crossing point 77 (see FIG. 6) of the extension target current TC, and the judgment section 73 performs the judgment as to whether the cumulative value ACC of the extension target current TC calculated by the cumulative value calculation section 71 exceeds a prescribed current cumulative threshold value ACCth, and in a case where the cumulative value ACC of the extension target current TC exceeds the current cumulative threshold value ACCth as a result of the judgment, the judgment section 73 makes the judgment that the merging target current should be limited. Figure 6 ) of the extension target current TC as the start, and the judgment section 73 performs the judgment as to whether the cumulative value ACC of the extension target current TC calculated by the cumulative value calculation section 71 exceeds a prescribed current cumulative threshold value ACCth, and in a case where the cumulative value ACC of the extension target current TC exceeds the current cumulative threshold value ACCth as a result of the judgment, the judgment section 73 makes the judgment that the merging target current should be limited.

[0145] In the electric suspension device 11 based on the second viewpoint, the cumulative value calculation section 71 included in the target load operation section 43 calculates the cumulative value ACC of the extension target current TC starting from the zero-crossing point 77 of the extension target current TC. The judgment section 73 performs the judgment as to whether the cumulative value ACC of the extension target current TC calculated by the cumulative value calculation section 71 exceeds a prescribed current cumulative threshold value ACCth.

[0146] In a case where the cumulative value ACC of the extension target current TC exceeds the current cumulative threshold value ACCth as a result of the judgment, the judgment section 73 makes the judgment that the merging target current should be limited. Thus, for example, compared with a comparative example in which the judgment section 73 makes the judgment that the merging target current should be limited in a case where the extension target current TC exceeds a prescribed current threshold value, the absorption of the vibration in which a large input is generated in the damper and a large current is momentarily required is not hindered.

[0147] According to the electric suspension device 11 based on the second viewpoint, when the integrated value ACC of the telescopic target current TC starting from the zero-crossing point 77 of the telescopic target current TC exceeds the current integration threshold value ACCth, a determination is made to limit the combined target current. Therefore, even when a large input is generated by the shock absorber, the large input can be appropriately buffered to maintain comfortable ride quality.

[0148] In addition, the electric suspension device 11 based on the third aspect can adopt the following structure: in the electric suspension device 11 based on the second aspect, when the judgment unit 73 makes a judgment that the combined target current should be limited, the target current correction unit 75 corrects the telescopic target current TC by multiplying the telescopic target current TC by a prescribed correction ratio RT to limit the telescopic target current TC. The above-mentioned correction ratio RT has the following characteristics: its initial value is set to a value less than 1, and in the interval where the integrated value ACC of the telescopic target current TC exceeds the current integration threshold value ACCth and increases, its value gradually decreases as time passes.

[0149] In the electric suspension device 11 based on the third aspect, when the determination unit 73 determines that the combined target current should be limited, the target current correction unit 75 corrects the expansion and contraction target current TC by multiplying the expansion and contraction target current TC by a predetermined correction ratio RT to thereby limit the expansion and contraction target current TC.

[0150] Here, the correction ratio RT has the following characteristics: its initial value is set to a value of 1 or less, and its value gradually decreases over time during a period in which the integrated value ACC of the telescopic target current TC exceeds the current integration threshold ACCth and increases. Therefore, the value of the telescopic target current TC after correction in this period gradually decreases over time relative to the value of the telescopic target current TC before correction.

[0151] As a result, when it is determined that the combined target current should be limited, the value of the expansion / contraction target current TC can be limited so as to gradually decrease with the passage of time.

[0152] According to the electric suspension device 11 based on the third viewpoint, when it is determined that the combined target current should be limited, the value of the telescopic target current TC related to the ride comfort of the vehicle is limited to gradually decrease over time. Therefore, compared with the electric suspension device 11 based on the second viewpoint, it is possible to improve the effect of ensuring the handling stability of the vehicle 10 and achieving improved ride comfort.

[0153] In addition, the electric suspension device 11 based on the fourth aspect may adopt the following structure: in the electric suspension device 11 based on the third aspect, even when the determination unit 73 determines that the combined target current should be limited, the target current correction unit 75 cancels the correction of limiting the telescopic target current TC when the telescopic target current TC0 before the current correction is lower than the telescopic target current TC1 after the previous correction.

[0154] In the electric suspension device 11 based on the fourth aspect, even when the determination unit 73 determines that the combined target current should be limited, the target current correction unit 75 cancels the correction for limiting the telescopic target current TC if the telescopic target current TC0 before the current correction is lower than the telescopic target current TC1 after the previous correction.

[0155] Here, the case where the telescopic target current TC0 before the current correction is lower than the telescopic target current TC1 after the previous correction is assumed to be a case where the value of the telescopic target current TC0 before the current correction is low enough to not require limitation. In such a case, the requirement to limit the combined target current is already low. Therefore, the correction to limit the telescopic target current TC is released.

[0156] According to the electric suspension device 11 based on the fourth aspect, even when a determination is made that the combined target current should be limited, if the telescopic target current TC0 before the current correction is lower than the telescopic target current TC1 after the previous correction, the correction to limit the telescopic target current TC is released. Therefore, compared with the electric suspension device 11 based on the third aspect, it is possible to further improve the effect of ensuring the handling stability of the vehicle 10 and achieving improved ride comfort.

[0157] The electric suspension device 11 according to the fifth aspect may be configured such that, in the electric suspension device 11 according to the second to fourth aspects, the integrated value calculation unit 71 initializes the integrated value ACC of the telescopic target current TC to zero when the telescopic target current TC passes through zero.

[0158] In the electric suspension device 11 based on the fifth aspect, the integrated value ACC of the telescopic target current TC is initialized to zero at the time when the telescopic target current TC crosses zero.

[0159] Here, two scenarios are envisioned for the zero crossing of the telescopic target current TC. The first scenario involves the sign of the telescopic target current TC being reversed from positive (powering) to negative (regeneration) (zero crossing). The second scenario involves the sign of the telescopic target current TC being reversed from negative (regeneration) to positive (powering) (zero crossing).

[0160] The reason why the integrated value ACC of the expansion / contraction target current TC is initialized to zero using the timing when the expansion / contraction target current TC crosses zero is as follows.

[0161] That is, the cumulative value ACC of the telescopic target current TC is calculated for each case where the sign of the telescopic target current TC is positive (power running) and for each case where the sign of the telescopic target current TC is negative (regeneration). This is because it is useful in appropriately managing the operating load of the electric motor 31 provided in the electromagnetic actuator 13 during each power running / regeneration.

[0162] According to the electric suspension device 11 based on the fifth aspect, the integrated value ACC of the telescopic target current TC is initialized to zero when the telescopic target current TC crosses zero. Therefore, the operating load of the electric motor 31 included in the electromagnetic actuator 13 can be appropriately managed during each power running / regeneration.

[0163] [Other Implementation Methods]

[0164] The multiple embodiments described above illustrate examples of the present invention. Therefore, these embodiments are not intended to limit the technical scope of the present invention. This is because the present invention can be implemented in various ways without departing from its gist or its main features.

[0165] Furthermore, 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.

[0166] Furthermore, in the description of the electric suspension device 11 according to the embodiment of the present invention, the drive control unit 49 that independently controls the drive of the plurality of electromagnetic actuators 13 has been mentioned.

[0167] Specifically, the drive control unit 49 can independently control the drive of the electromagnetic actuator 13 included in each of the four wheels.

[0168] Furthermore, the electromagnetic actuators 13 provided for each of the four wheels may be driven and controlled independently for the front and rear wheels, and independently for the left and right wheels.

[0169] 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.

[0170] As a driving structure of the electromagnetic actuator 13 , for example, 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 stroke speed of the actuator and a sprung state quantity of the vehicle; a target load calculation unit that calculates a damping target load associated with unsprung vibration damping control based on the stroke speed, calculates a telescoping target load associated with sprung vibration damping control based on the sprung state quantity, and calculates a combined target load by combining the damping target load and the telescoping target load; and a load control unit that performs load control of the actuator using the combined target load, The electric suspension device is characterized in that: The target load calculation unit includes: a determination unit that determines whether a combined target current related to the combined target load should be limited; and a target current correction unit that, when the determination unit determines that the combined target current should be limited, maintains the attenuation target current associated with the attenuation target load and, on the other hand, performs correction to limit the telescoping target current associated with the telescoping target load; The combined target current is obtained by combining the attenuation target current and the expansion target current corrected by the target current correction unit. The target load calculation unit further includes an integrated value calculation unit that calculates an integrated value of the telescopic target current starting from a zero-crossing point of the telescopic target current. The determination unit determines whether the integrated value of the expansion / contraction target current calculated by the integrated value calculation unit exceeds a predetermined current integration threshold value, and determines that the combined target current should be limited if the integrated value of the expansion / contraction target current exceeds the current integration threshold value.

2. The electric suspension device according to claim 1, characterized in that The target current correction unit corrects the expansion target current by multiplying the expansion target current by a predetermined correction ratio to limit the expansion target current when the determination unit determines that the combined target current should be limited. The correction ratio has a characteristic that its initial value is set to a value equal to or less than 1, and its value gradually decreases with time in a section where the integrated value of the expansion / contraction target current exceeds the current integration threshold and increases.

3. The electric suspension device according to claim 2, characterized in that: Even when the determination unit determines that the combined target current should be limited, the target current correction unit cancels the correction for limiting the telescopic target current if the telescopic target current before this correction is lower than the telescopic target current after the previous correction.

4. The electric suspension device according to any one of claims 1 to 3, characterized in that: The integrated value calculation unit initializes the integrated value of the expansion / contraction target current to zero when the expansion / contraction target current passes through zero.

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