JP2012148734A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device improving ride quality of a vehicle by alleviating a sudden change of a generated damping force of a shock absorber.SOLUTION: The suspension device 1 includes the shock absorber 2 interposed between a vehicle body and wheels of the vehicle and exerting the damping force controlling relative movement of the vehicle body and the wheels in a vertical direction, a damping force adjusting mechanism 3 adjusting the damping force, and a control device 4 controlling the damping force adjusting mechanism 3 based on a target damping force. The control device 4 includes a correcting means 43 correcting the target damping force so that the change of the generated damping force of the shock absorber may be alleviated when the expansion/contraction speed of the shock absorber 2 is zero and a predetermined value. The correction means 43 corrects the generated damping force by offset toward speed increase by the difference β between a speed threshold value Vand a predetermined speed Vuntil the expansion/contraction speed x of the shock absorber 2 reaches zero when the expansion/contraction speed x exceeds the speed threshold value V, and when the difference is from β to zero, correction is made to minimize the generated damping force.

Description

  The present invention relates to a suspension device.

  Conventionally, in a suspension device, for example, a shock absorber that is interposed between a vehicle body and a wheel in a vehicle and exhibits a damping force that suppresses relative movement in the vertical direction between the vehicle body and the wheel, and a supplied current Some include a damping force adjustment mechanism that adjusts the damping force in the shock absorber according to the amount and a control device that controls the damping force adjustment mechanism (see, for example, Patent Document 1).

  As shown in FIG. 16, the shock absorber in this suspension device has a damping characteristic (the shock absorber's shock absorber) even if the amount of current supplied to the damping force adjusting mechanism is changed, except when the expansion / contraction speed of the shock absorber is in an extremely low speed range. It has the property that the slope of the damping force with respect to the expansion / contraction speed does not change, knows the minimum damping force of the shock absorber in advance, and determines the minimum at the expansion / contraction speed of the shock absorber at that time from the damping force to be generated by the shock absorber. If the damping force is subtracted to obtain the target damping force, the amount of current to be supplied from the target damping force to the damping force adjusting mechanism can be obtained regardless of the expansion / contraction speed.

  However, in the suspension device disclosed in Japanese Patent Application Laid-Open No. 2008-12959, when the expansion / contraction speed of the shock absorber is in an extremely low speed region, the damping force is not exhibited according to the target damping force, and the shock absorber expands / contracts. Since the damping force cannot be generated in the same direction as the direction, the target damping force is not 0, and the shock absorber can generate a damping force by switching the expansion / contraction direction of the shock absorber. Since the slope of the damping characteristic is greatly changed by O, the change in the damping force generated by the shock absorber becomes steep.

  In order to avoid this sudden change in damping force, a technique for mitigating a steep change in generated damping force by obtaining a supply current to be output to the damping force adjustment mechanism from a current command using a hyperbolic tangent function is disclosed. (For example, refer to Patent Document 2).

JP 2008-12959 A JP 2010-52488 A

  The technique of Patent Document 2 is effective in that it can alleviate a sudden change in damping force when a current command transitions from outside the damping force control range to within the damping force control range, but the expansion / contraction direction of the shock absorber is switched, When the damping force that has been output until then has to be minimized, there is a case where hysteresis occurs and the damping force cannot be minimized immediately, and the riding comfort in the vehicle may be deteriorated.

  This is because the frequency of the unsprung vibration of the vehicle is as high as approximately 10 Hz to 20 Hz, and the damping force adjusting mechanism in the shock absorber of Patent Document 1 is set so that there is no hysteresis for obtaining the supply current from the current command. In addition, when a solenoid valve is used for the damping force adjustment mechanism, there is an inductive load in the circuit of the damping force adjustment mechanism, and it is useless to reduce the actual current due to the time constant of the circuit. Since time is generated, the supply current cannot be controlled as determined from the command current. For example, on the condition that the shock absorber exerts a damping force in the contraction direction, considering that the shock absorber contracts and then expands and then contracts, the shock absorber itself exerts a force to actively expand and contract. In this case, when the shock absorber is contracted, the damping force of the shock absorber is reduced as much as possible. Assuming that the damping force can be minimized when the current supplied to the damping force adjusting mechanism by the shock absorber is zero, as shown in FIG. 17, when the shock absorber is in the contraction stroke, the damping force is supplied to the damping force adjusting mechanism. The actual current is maintained at 0 (line I1 in the figure), and when the shock absorber starts to extend, the sudden change in the actual current supplied to the damping force adjusting mechanism is alleviated and gradually increased. As a result, the current value increases to a current value that exhibits the target damping force (line I2 in the figure). Then, when the shock absorber further reverses and reaches the contraction stroke, the supply current gradually decreases. However, as described above, there is a problem of dead time, and the actual current immediately becomes 0. However, a delay occurs in the response, and the hysteresis shifts toward the contraction side with respect to the line I1 in the figure (line I3 in the figure).

  When hysteresis occurs in this way, the actual current remains in switching the expansion / contraction direction of the shock absorber, and the shock absorber exerts an unintended damping force. The force may change suddenly and the ride comfort of the vehicle may be deteriorated.

  Accordingly, the present invention has been developed to improve the above-described problems, and the object of the present invention is to reliably reduce sudden changes in the damping force generated by the shock absorber and improve the riding comfort in the vehicle. A suspension device is provided.

  In order to achieve the above object, the problem-solving means of the present invention includes a shock absorber that is interposed between a vehicle body and a wheel in a vehicle and exhibits a damping force that suppresses relative movement in the vertical direction between the vehicle body and the wheel. The suspension device includes a damping force adjusting mechanism that adjusts the damping force and a control device that controls the damping force adjusting mechanism based on the target damping force. Compensating means for reducing the change in the damping force generated by the shock absorber at a predetermined speed is provided, and when the telescopic speed of the shock absorber exceeds a speed threshold set to a value exceeding the predetermined speed, the telescopic speed is zero. Until it becomes, the expansion / contraction speed for reducing the generated damping force change is offset to the speed increasing side by the difference between the speed threshold and the predetermined speed, and the target damping force is corrected from 0 to 0. And correcting to.

  According to the suspension device of the present invention, it is possible to reliably relieve a sudden change in the damping force generated by the shock absorber and improve the riding comfort in the vehicle.

1 is a system configuration diagram of a suspension device according to an embodiment. It is the figure which showed an example of the buffer of the suspension apparatus in one embodiment. It is the figure which showed the characteristic (damping characteristic) of the damping force with respect to the expansion-contraction speed of the buffer of the suspension apparatus in one Embodiment. It is a figure which shows the relationship between target damping force and the expansion-contraction speed of a buffer. It is a figure which shows the relationship between the target damping force after correction | amendment when the expansion-contraction speed of a buffer does not exceed a speed threshold value, and the expansion-contraction speed of a buffer. It is a figure explaining the correlation of target damping force and predetermined speed. It is a figure which shows the relationship between the target damping force after correction | amendment until the expansion-contraction speed of a shock absorber exceeds a speed threshold value, and becomes the expansion-contraction speed of a shock absorber. It is a figure explaining the correction process by a correction means according to the motion of an actual shock absorber. It is a figure explaining the electric current which actually flows into the damping force adjustment mechanism with respect to the instruction | command corrected by the correction | amendment means. It is a figure explaining the shrinkage | contraction side map used for the calculation which obtains a target electric current command value from the target damping force of the suspension apparatus in one embodiment. It is a figure explaining the expansion | extension side map used for the calculation which obtains a target electric current command value from the target damping force of the suspension apparatus in one embodiment. It is the figure which showed an example of the target damping force after correction | amendment of the suspension apparatus in one Embodiment. It is a figure explaining the shrinkage | contraction side map used for the calculation which obtains a target electric current command value from the target damping force of the suspension apparatus in other embodiment. It is a figure explaining the expansion | extension side map used for the calculation which obtains a target evaluation current command value from the target damping force of the suspension apparatus in other embodiment. It is a figure explaining the gain by which the target electric current command value or target voltage command value of the suspension apparatus in other embodiment is multiplied. It is the figure which showed the characteristic (damping characteristic) of the damping force with respect to the expansion-contraction speed of the buffer of the conventional suspension apparatus. It is a figure explaining the relationship between the actual electric current which flows into the damping-force adjustment mechanism in the buffer of the conventional suspension apparatus, and the expansion-contraction speed of a buffer.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, a suspension device 1 according to an embodiment is provided between a vehicle body and a wheel in a vehicle (not shown) and exhibits a damping force that suppresses relative movement in the vertical direction between the vehicle body and the wheel. The shock absorber 2 includes a damping force adjustment mechanism 3 that can adjust the damping force in the shock absorber 2 according to the amount of current supplied, and a control device 4 that controls the damping force adjustment mechanism 3. Yes.

  Hereinafter, each member will be described in detail. As shown in FIG. 2, the shock absorber 2 is inserted into the cylinder 20, the piston 21 slidably inserted into the cylinder 20, and the movably inserted into the cylinder 20. A piston rod 22 connected to the piston 21, two pressure chambers 23 and 24 that are partitioned by the piston 21 in the cylinder 20 and filled with a magnetorheological fluid, and a passage 25 that communicates the pressure chambers 23 and 24 with each other. And a coil 26 that gives magnetism to the magnetorheological fluid passing through the passage 25, and is interposed between the vehicle body and the wheel of the vehicle. The shock absorber 2 includes a coil 26 when the magnetorheological fluid filled in the pressure chambers 23 and 24 passes through the passage 25 in accordance with the expansion and contraction operation that is the relative movement of the cylinder 20 and the piston rod 22 in the axial direction. The magnetism is applied by energizing the motor, resistance is given to the movement of the magnetorheological fluid, a differential pressure is generated between the pressure chambers 23 and 24, and a damping force that suppresses the expansion and contraction operation is exerted. The relative movement of the direction is suppressed. When the shock absorber 2 is a single rod type shock absorber, the shock absorber 2 includes a gas chamber and a reservoir to compensate for the volume of the piston rod 22 entering and exiting the cylinder 20 (not shown). Further, although not shown in detail, when the shock absorber 2 is provided with a reservoir and is set to a uniflow type in which fluid is discharged through a passage leading from the inside of the cylinder 20 to the reservoir even when the shock absorber 2 extends or contracts, the cylinder 20 A coil may be provided in the middle of the passage leading from the reservoir to the reservoir so as to exert a damping force by imparting resistance to the fluid flow.

  Therefore, in this embodiment, the damping force adjusting mechanism 3 is the coil 26 that gives magnetism to the magnetorheological fluid. By adjusting the amount of current that is given to the coil 26, the strength of the magnetic field that is given to the magnetorheological fluid is increased. By adjusting the height, the magnitude of the resistance given to the flow of the magnetorheological fluid passing through the passage 25 can be adjusted, and the generated damping force of the shock absorber 2 can be adjusted. In the case of this embodiment, as shown in FIG. 3, unless current is supplied to the coil 26, magnetism is not given to the magnetorheological fluid, and the damping characteristic of the shock absorber 2 is the minimum indicated by the one-dot chain line in the figure. As the amount of current supplied to the coil 26 is larger, the generated damping force of the shock absorber 2 is larger, and the maximum current supply amount limited as hardware is given to the coil 26. The damping characteristic of the shock absorber 2 is the maximum damping characteristic H indicated by the solid line in the figure. Further, in the case of this embodiment, it is indicated by a broken line in FIG. 3 according to the amount of current supplied to the coil 26 except for the case where the expansion / contraction speed of the shock absorber 2 is in an extremely low speed range so that the control becomes easy. As described above, the attenuation characteristic can be adjusted in the vertical direction from the minimum L to the maximum H while keeping the inclination constant. In the present embodiment, in order to explain the change of the attenuation characteristic, the expansion / contraction speed of the shock absorber is divided into a very low speed region, but in the very low speed region, the absolute value of the expansion / contraction speed of the shock absorber is from 0. A range up to an arbitrary speed is shown, and the range can be arbitrarily set according to the design of the shock absorber 2. In addition, in the place shown in FIG. 3, the damping force in the direction to suppress the contraction of the shock absorber (extension direction) is positive, the damping force in the direction to suppress the expansion of the shock absorber (contraction direction) is negative, and the expansion / contraction speed Treats the contraction direction of the shock absorber as positive and treats the expansion direction of the shock absorber as negative. This is the same except for the processing in the correction unit 43 among the processing in the control device 4 to be described later.

  The above-described configuration of the shock absorber 2 is an example. For example, when the shock absorber 2 is filled with electrorheological fluid in the pressure chambers 23 and 24, the damping force adjusting mechanism 3 applies a voltage to the passage 25. What is necessary is just to be able to apply, and what is necessary is just to carry out by adjusting supply voltage in the case of adjustment of damping force. Further, when the pressure chambers 23 and 24 are filled with a liquid or gas other than the magnetorheological fluid or the electrorheological fluid, the damping force adjusting mechanism 3 is a solenoid valve provided in the middle of the passage 25 to change the flow path depending on the amount of supplied current. The generated damping force of the shock absorber 2 may be controlled by adjusting the area.

  Furthermore, the shock absorber 2 may be an electromagnetic shock absorber that exhibits a damping force that suppresses the relative movement of the sprung member and the unsprung member by electromagnetic force in addition to the above. A motor and a motion conversion mechanism that converts a rotational motion of the motor into a linear motion are configured, or a linear motor. Thus, when the shock absorber 2 is an electromagnetic shock absorber, the damping force adjusting mechanism 3 may be a motor driving device that adjusts the current flowing through the motor or linear motor. As the motion conversion mechanism, for example, a feed screw mechanism including a screw shaft and a ball screw nut screwed to the screw shaft or a rack and pinion can be employed.

  In this embodiment, as shown in FIG. 1, the control device 4 controls the damping force of the shock absorber 2 in accordance with the skyhook control side. Therefore, the vertical acceleration of the vehicle body is controlled. , And a stroke sensor 6 for detecting the expansion / contraction speed of the shock absorber 2. Furthermore, the control device 4 includes a target damping force calculation unit 41 for obtaining the target damping force, a limiter 42 that performs limiter processing on the target damping force, a correction unit 43 that corrects the target damping force after the limiter processing, and a corrected target. A target current command value calculation unit 44 that obtains a target current command value from the damping force by map calculation, and a driver 45 that receives the target current command value and supplies current to the coil 26 as the damping force adjustment mechanism 3 are provided. Yes.

  The target damping force calculation unit 41, the limiter 42, the correction unit 43, and the target current command value calculation unit 44 in the control device 4 are not shown in the figure, but are specifically used for processing necessary for controlling the shock absorber 2, for example. A storage device such as a ROM (Read Only Memory) in which a program to be stored is stored, a calculation device such as a CPU (Central Processing Unit) that executes processing based on the program, and a RAM that provides a storage area to the CPU ( The units 41, 42, 43, and 44 may be realized by the CPU executing the above-described program, as long as it is configured to include a storage device such as a random access memory (Random Access Memory).

  The target damping force calculation unit 41 obtains the vertical velocity of the vehicle body by integrating the vertical acceleration detected by the acceleration sensor 5, and obtains the necessary damping force by multiplying this vertical velocity by the Skyhook damping coefficient. Then, the minimum damping force at the expansion / contraction speed when power is not supplied to the coil 26 as the damping force adjusting mechanism 3 from the expansion / contraction speed of the shock absorber 2 is subtracted from the required damping force to obtain the target. Find the damping force. As described above, the target damping force is obtained by removing the minimum damping force component indicated by the damping characteristic L in FIG. 3 from the required damping force. Then, since the damping characteristic of the shock absorber 2 has the same slope regardless of the amount of current supplied to the coil 26 when the expansion / contraction speed of the shock absorber exceeds the extremely low speed range, the minimum damping force is subtracted as described above. The relationship between the target damping force obtained in this way and the expansion / contraction speed of the shock absorber is as shown in FIG. 4 in which the damping characteristic shown in FIG. The damping force and the amount of current to be supplied to the damping force adjusting mechanism 3 have a one-to-one relationship.

  That is, if the target damping force is obtained, the amount of current to be supplied to the damping force adjusting mechanism 3 is determined. The expansion / contraction speed of the shock absorber 2 can be obtained by differentiating the stroke (stretching displacement) of the shock absorber 2 detected by the stroke sensor 6, but the acceleration for detecting the vertical acceleration by a spindle or the like that supports the wheel. A sensor may be provided to integrate the vertical acceleration of the wheel to obtain the vertical speed of the wheel, and the difference between the vertical speed of the vehicle body and the vertical speed of the wheel may be taken to obtain the expansion / contraction speed of the shock absorber 2.

  Thus, the control device 4 calculates the vertical speed of the vehicle body by integrating the vertical acceleration detected by the acceleration sensor 5, differentiates the stroke of the shock absorber 2 detected by the stroke sensor 6, and determines the expansion / contraction speed of the shock absorber 2. Calculate the required damping force by multiplying the vertical speed by the Skyhook damping coefficient, find the minimum damping force of the shock absorber 2 at the stretching speed from the stretching speed of the shock absorber 2, and subtract the minimum damping force from the necessary damping force. To obtain the target damping force. Further, a target current command value corresponding to the amount of current supplied to the coil 26 as the damping force adjusting mechanism 3 is obtained from the target damping force. The amount of current supplied directly to the damping force adjusting mechanism 3 from the thus obtained target damping force. , The target damping force is set to a value at which the expansion / contraction speed of the shock absorber 2 is in an extremely low speed range and the shock absorber 2 cannot actually be generated, and the expansion / contraction direction of the shock absorber 2 is switched so that the shock absorber has a damping force. When it becomes a state where it can be generated, or when the target damping force exceeds the maximum damping force within the range of damping force that can be generated by the shock absorber 2, the change in the damping force of the shock absorber 2 becomes steep.

Therefore, in the present invention, the correction unit 43 is provided as a correction unit that corrects a command given to the damping force adjusting mechanism 3 and relaxes a change in the damping force generated by the shock absorber 2. In this embodiment, the correction unit 43 corrects a command to be given to the damping force adjusting mechanism 3 by correcting the target damping force. Specifically, the correcting unit 43 includes a shock absorber. The expansion / contraction speed of the shock absorber 2 exceeds the speed threshold V _p2 when the expansion / contraction speed of the shock absorber 2 is within the speed threshold V _p2 without exceeding the speed threshold V _p2 set to a value exceeding the predetermined speed V _p1. The correction is performed by changing the expansion / contraction speed for relieving a change in the damping force generated by the shock absorber 2 between the time when the value is zero and the time when the shock absorber 2 is zero. In addition, this correction | amendment part 43 correct | amends by making the expansion / contraction direction of the buffer 2 different from the direction of the target damping force into positive, and making the expansion / contraction direction of the buffer 2 the same as the direction of target damping force negative.

First, the processing of the correction unit 43 when the expansion / contraction speed of the shock absorber 2 does not exceed the speed threshold V _p2 set to a value exceeding the income speed V _p1 and is within the range of the speed threshold V _p2 will be described. Specifically, the correcting unit 43 sets the expansion / contraction direction of the shock absorber 2 in the opposite direction to the direction of the target damping force (the damping force generation direction in which the target damping force instructs the shock absorber 2), and the expansion / contraction of the shock absorber 2 If the speed is x, when the expansion rate x of the shock absorber 2 is in the range of 0 ≦ x ≦ _{V p1} / 2 is determined by calculating the correction coefficient _{^{α α = 2x 2 / V p1}} 2, the shock absorber 2 When the expansion / contraction speed x is in the range of V _p1 / 2 <x ≦ V _p1 , the correction coefficient α is obtained by calculating α = −2 (x−V _p1 ) ² / V _p1 ² +1, and the correction coefficient thus obtained is obtained. The target damping force is corrected by multiplying α by the target damping force. The shock absorber 2 is a passive shock absorber and cannot spontaneously generate thrust. When the target damping force is the same direction as the expansion / contraction direction of the shock absorber 2, that is, when the direction of the target damping force is a direction that assists the expansion / contraction of the shock absorber, the shock absorber 2 has a damping force in the same direction as the target damping force. Therefore, it is necessary to minimize the generated damping force of the shock absorber 2, that is, to minimize it. Therefore, when the direction of the target damping force and the expansion / contraction direction of the shock absorber 2 are the same, specifically, the expansion / contraction speed x is negative in accordance with the definition of the sign of the expansion / contraction direction of the shock absorber 2 employed in the correction unit 43. When the value is taken, the correction unit 43 corrects the target damping force by setting the correction coefficient α to 0, and the corrected target damping force becomes 0. Further, when the expansion / contraction speed x of the shock absorber 2 is in a range exceeding the predetermined speed V _p1 , the correction unit 43 needs to correct the target damping force because the expansion / contraction direction of the shock absorber 2 is different from the direction of the target damping force. Since there is no correction, the correction coefficient α is set to 1, and the corrected target damping force is calculated.

Then, a case where the direction of the target damping force is a direction in which the shock absorber 2 is extended and the target damping force is set to a certain value will be described as an example. The corrected target damping force is indicated by a solid line in FIG. As shown, when the shock absorber 2 exhibits an extension operation and coincides with the direction of the target damping force, it becomes 0, and the shock absorber 2 exhibits a contraction operation and differs from the direction of the target damping force. 2 and below the upper limit damping force of 2 and the expansion / contraction speed of the shock absorber 2 is from 0 to a predetermined speed V _p1 or less, it varies depending on the expansion / contraction speed x of the shock absorber 2, and the expansion / contraction speed x of the shock absorber 2 is When the speed exceeds the predetermined speed V _p1 , the correction coefficient becomes 1, and the corrected target damping force coincides with the target damping force calculated by the target damping force calculation unit 41. Here, the predetermined speed V _p1 is preferably set so that the corrected target damping force threshold is within the range of the damping force that can be generated by the shock absorber 2, and takes a constant value that does not vary with respect to the target damping force. Alternatively, it may be changed depending on the magnitude of the target damping force. Further, the case where the direction of the target damping force is a direction in which the shock absorber 2 is contracted and the target damping force is set to a certain value will be described as an example. The corrected target damping force is indicated by a broken line in FIG. As shown, when the shock absorber 2 exhibits a contraction operation and coincides with the direction of the target damping force, it becomes 0, and the shock absorber 2 exhibits an extension operation and differs from the direction of the target damping force. 2 and below the upper limit damping force of 2 and the expansion / contraction speed of the shock absorber 2 is from 0 to a predetermined speed V _p1 or less, it varies depending on the expansion / contraction speed x of the shock absorber 2, and the expansion / contraction speed x of the shock absorber 2 is When the speed exceeds the predetermined speed V _p1 , the correction coefficient becomes 1, and the corrected target damping force coincides with the target damping force calculated by the target damping force calculation unit 41. The expansion / contraction speed x is positive in the expansion / contraction direction of the shock absorber 2 in the direction opposite to the direction of the target damping force, but in FIG. Since the damping force in the direction of contracting is a negative value, the corrected target damping force is as shown by the broken line.

Taking the case where the direction of the target damping force is the direction in which the shock absorber 2 is extended as an example, as shown in FIG. 6, the target damping force is maximum and the amount of current supplied to the damping force adjustment mechanism 3 is maximum. The damping force range that can be output by the shock absorber 2 with respect to the damping characteristic k1 is between the damping characteristic k1 and the expansion / contraction speed axis, and the corrected target damping force locus G1 falls within this output possible range. In this case, the predetermined speed V _p1 needs to be equal to or higher than V _p1 (1). On the other hand, when the target damping force is reduced and the amount of current supplied to the damping force adjustment mechanism 3 is reduced to become the damping characteristic k2, the corrected target damping force locus G2 is within the output possible range. In the case of storing, it is necessary to set the predetermined speed to V _p1 (2) or more. When the target damping force is further reduced and the amount of current supplied to the damping force adjusting mechanism 3 is reduced to obtain the damping characteristic k3, the corrected target damping force locus G3 is within the output possible range. The predetermined speed needs to be V _p1 (3) or more. Therefore, in the case of this shock absorber 2, it can be seen that the greater the target damping force, the greater the predetermined speed _Vp1 must be. In this case the target damping force is small, the predetermined speed V _p1 of the target damping force after correction becomes equal to the target damping force can also be reduced, thus the predetermined speed V _p1 of the target damping force as a parameter By changing it, there is an advantage that the corrected target damping force can quickly follow the target damping force before correction.

Next, the processing of the correction unit 43 when the expansion / contraction speed x of the shock absorber 2 exceeds the speed threshold value _Vp2 and becomes 0 will be described. Specifically, the correction unit 43, when the difference of the speed threshold V _p2 and the predetermined speed V _p1 from the speed threshold V _p2 is a value obtained by subtracting the predetermined speed V _p1 and beta, once stretching speed x is x If the expansion / contraction speed x of the shock absorber 2 is in the range of β ≦ x ≦ V _p2 −V _p1 / 2 until the expansion / contraction speed x reaches 0 when> V _p2 is satisfied, the correction coefficient α is set to α = 2 ( x−β) ² / V _p12 ² is obtained by calculation, and when the expansion / contraction speed x of the shock absorber 2 is in the range of V _p2 −V _p1 / 2 <x ≦ V _p2 , the correction coefficient α is set to α = − 2 (x−β−V _p1 ) ² / V _p1 ² +1 is calculated, and when the expansion / contraction speed x of the shock absorber 2 is in the range of 0 ≦ x <β, the correction coefficient α is set to 0, and The target damping force is corrected by multiplying the obtained correction coefficient α by the target damping force. The shock absorber 2 is a passive shock absorber and cannot spontaneously generate thrust. When the target damping force is in the same direction as the expansion / contraction direction of the shock absorber 2, the shock absorber 2 cannot exert the damping force in the same direction as the target damping force, and therefore the generated damping force of the shock absorber 2 is reduced as much as possible. There is a need. Therefore, when the direction of the target damping force and the expansion / contraction direction of the shock absorber 2 are the same, the correction unit 43 corrects the target damping force by setting the correction coefficient α to 0, and the corrected target damping force becomes 0. Further, when the expansion / contraction speed x of the shock absorber 2 is in a range exceeding the speed threshold value V _p2 , the correction unit 43 needs to correct the target damping force because the expansion / contraction direction of the shock absorber 2 is different from the direction of the target damping force. Since there is no correction, the correction coefficient α is set to 1, and the corrected target damping force is calculated.

From the above, when the expansion / contraction speed x of the shock absorber 2 exceeds the speed threshold value V _p2 and becomes 0, the direction of the target damping force is the direction in which the shock absorber 2 is extended and the target damping force is a certain value. As an example, the corrected target damping force is different from the direction of the target damping force as the shock absorber 2 exhibits contraction operation as shown by the solid line in FIG. a less damping force, when stretching speed of the shock absorber 2 is equal to or less than the speed threshold V _p2 from β is buffer 2 of the telescopic velocity x Thus changes, shock absorber 2 of the telescopic speed x speed threshold V _p2 Exceeds the value, the correction coefficient becomes 1, and the corrected target damping force coincides with the target damping force calculated by the target damping force calculation unit 41. When the direction of the target damping force is a direction in which the shock absorber 2 is contracted, the corrected target damping force is as indicated by a broken line in FIG. In FIG. 7, the speed in the extension direction of the shock absorber 2 is a negative value, and the damping force in the direction of contracting the shock absorber 2 is a negative value, so that the corrected target damping force is as shown by a broken line.

Further, the correction process of the correction unit 43 will be described in accordance with the actual movement of the shock absorber 2. In the case where the direction of the target damping force does not change and the expansion / contraction speed x of the shock absorber 2 changes from a negative value to a positive value to increase the speed and then reverses and changes to negative, the target damping force by the correcting unit 43 This correction is as shown in FIG. In the process in which the expansion / contraction speed x of the shock absorber 2 changes from a negative value to a positive value and the speed increases, as shown by the solid line in FIG. 8, when the expansion / contraction speed x is negative, the correction coefficient α Is corrected as described above in the range of 0 ≦ x ≦ V _p1 until the speed threshold V _p2 is exceeded, and is corrected as a correction coefficient α = 1 if the speed exceeds the predetermined speed V _p1 . Thereafter, in the process in which the expansion / contraction speed x increases and exceeds the speed threshold V _p2 , the expansion / contraction speed x becomes slow and eventually becomes 0, and the expansion / contraction direction reverses and the expansion / contraction speed x becomes negative, the broken line in FIG. As shown, when the expansion / contraction speed x is in the range of β ≦ x ≦ V _p2 −V _p1 / 2, the correction is made as described above. When the expansion speed exceeds the predetermined speed, the correction coefficient α = 1 is corrected, and the expansion / contraction speed x is x < In the range of β, the correction coefficient α = 0 is corrected, and when the expansion / contraction speed x becomes negative, the correction coefficient α = 0 is corrected. That is, the correction coefficient α when the expansion / contraction speed x of the shock absorber 2 exceeds the speed threshold V _p2 is as shown in FIG. 8 when the expansion / contraction speed x of the shock absorber 2 does not exceed the speed threshold V _p2 . relative correction coefficient alpha, is offset from the speed threshold V _p2 to the right in the drawing which is a difference β only speed up the side of the predetermined speed V speed threshold V _{p2 p1} is a value obtained by subtracting a predetermined speed V _p1 Yes. That is, when the expansion / contraction speed x does not exceed the speed threshold value V _p2 , the correction unit 43 serving as a correction unit changes the generated damping force of the shock absorber when the expansion speed of the shock absorber 2 is 0 and the predetermined speed V _p1 . However, when the expansion / contraction speed x exceeds the speed threshold V _p2 , the expansion / contraction speed for relaxing the damping force change generated by the shock absorber 2 is set to the speed threshold V _p2 and the predetermined speed V _p1 until the expansion / contraction speed x becomes zero. The generated damping force is corrected by offsetting the difference β to the speed increasing side, and the generated damping force is minimized in the range from the difference β to the expansion / contraction speed x.

By doing in this way, when the expansion / contraction speed x exceeds the speed threshold value _Vp2 , when the expansion / contraction speed x starts to decrease, the target damping force is corrected from an early stage and starts to decrease. Since the force is supplied as a command to the damping force adjusting mechanism 3 via the target current command value calculation unit 44 and the driver 45 in the subsequent stage, as shown in FIG. 9, when the expansion / contraction speed x starts to decrease as shown in FIG. Even if the current flowing through the damping force adjusting mechanism 3 is delayed with respect to the command given to the damping force adjusting mechanism 3 by changing from 0 to 0, the damping force adjusting mechanism can be used when the expansion / contraction speed x of the shock absorber 2 becomes zero. 3, the actual current flowing through the coil 26 can be reduced to zero. In FIG. 9, the solid line indicates a command corrected by correcting the target damping force by the correcting unit 43 serving as a correcting unit, and the broken line indicates the actual current flowing in the coil 26 of the damping force adjusting mechanism 3. Current is shown.

Here, the speed threshold V _p2 is is the may be set to a value greater than the predetermined speed V _p1, the difference β between the predetermined speed V _p1 is too low, the buffer to the coil 26 in the damping force adjusting mechanism 3 Since the current remains when the expansion / contraction speed of the device 2 is 0, the time constant in the circuit composed of the damping force adjusting mechanism 3 and the driver 45 for supplying the current (in this embodiment, including the coil 26) It is sufficient that the residual current is not generated when the expansion / contraction speed of the shock absorber 2 is zero, based on the time constant of the driver 45 circuit) and the unsprung vibration frequency during vehicle travel.

As for the speed threshold V _p2 , as long as the residual current does not occur when the expansion / contraction speed of the shock absorber 2 is 0, the value of the speed threshold V _p2 is set according to the magnitude of the target damping force as in the case of the predetermined speed V _p1. It may be made to change.

  Subsequently, the target current command value calculation unit 44 subsequent to the correction unit 43 obtains the amount of current from the corrected target damping force. The target current command value obtained by the target current command value calculation unit 44 is input to the driver 45, and the driver 45 outputs the current corresponding to the target current command value as a command to the damping force adjustment mechanism 3. The control device 4 adjusts the damping force of the shock absorber 2 through the damping force adjusting mechanism 3 by performing the above-described calculation. That is, in this case, the correction unit 43 is subsequent to the target damping force calculation unit 41 for obtaining the target damping force, and corrects the command given to the damping force adjustment mechanism 3 by correcting the target damping force.

  Specifically, the target current command value calculation unit 44 performs map calculation to obtain a target current command value from the target damping force. In this embodiment, the target current command value calculation unit 44 can also obtain the target current command value from the target damping force without performing the map calculation.

  There are two maps used for the map calculation. Specifically, the contraction side map M1 used when the shock absorber 2 operates in contraction, and the expansion side used when the shock absorber 2 operates in expansion. There is a map M2. That is, a map is prepared for each expansion / contraction direction of the shock absorber 2. As shown in FIG. 10, the contraction-side map M <b> 1 shows that when the direction of the target damping force is the same direction as the expansion / contraction direction of the shock absorber 2, that is, the shock absorber 2 is contracted and the target damping force is applied to the shock absorber 2. Corresponding to the case where the generation of the damping force in the contraction direction is instructed, the output lower limit line A1 that takes a constant value with respect to the change in the target damping force, and the direction of the target damping force is different from the expansion / contraction direction of the shock absorber 2. When the output upper limit is exceeded, that is, when the shock absorber 2 is contracted and the target damping force instructs the shock absorber 2 to generate a damping force in the extension direction, the target damping force When the output upper limit line B1 that takes a constant value with respect to the change, the output lower limit line A1, and the output upper limit line B1 are connected, and the direction of the target damping force is different from the expansion / contraction direction of the shock absorber 2, and the shock absorber 2 can output. That is, shock absorber 2 is contracted Damping force and an output enable line C1 which corresponds proportionally changes with respect to the target damping force when in the output range and instructs the generation of the damping force in the expanding direction to the shock absorber 2.

  On the other hand, as shown in FIG. 11, in the extension side map M2, the direction of the target damping force is the same as the expansion / contraction direction of the shock absorber 2, that is, the shock absorber 2 is extended and the target damping force is buffered. Corresponding to the case where the generation of the damping force in the extension direction is instructed to the damper 2, the output lower limit line A2 that takes a constant value with respect to the change in the target damping force, and the direction of the target damping force is the expansion / contraction direction of the shock absorber 2 Is different from the upper limit of the output, that is, the shock absorber 2 is extended and the target damping force instructs the shock absorber 2 to generate a damping force in the contraction direction, but the target exceeds the output upper limit. The output upper limit line B2 that takes a constant value with respect to the change of the damping force, the output lower limit line A2, and the output upper limit line B2 are connected, and the direction of the target damping force is different from the expansion / contraction direction of the shock absorber 2, and the shock absorber 2 outputs If possible, that is, the shock absorber 2 is extended The output possible line C2 that changes proportionally with respect to the target damping force is provided corresponding to the case where the target damping force instructs the shock absorber 2 to generate the damping force in the contraction direction and is within the output possible range. .

  In the contraction side map M1 and the expansion side map M2, the target damping force is a positive value that causes the shock absorber 2 to generate a damping force in the expansion direction, that is, the target damping force that causes the shock absorber 2 to exert a damping force that prevents contraction. The force value is positive, and the target damping force that generates damping force in the opposite direction is negative. In this embodiment, the target current command value becomes 0 or more regardless of the target damping force because the damping coefficient is adjusted by supplying current to the damping force adjusting mechanism 3. As described above, when the target damping force is within the output possible range of the shock absorber 2, the current applied to the damping force adjusting mechanism 3 and the generated damping force of the shock absorber 2 are in a proportional relationship. The output possible lines C1 and C2 in the side map M2 are linear because the target current command value changes proportionally according to the current value target damping force, but the relationship between the generated damping force of the shock absorber 2 and the current is nonlinear. In this case, the output possible lines C1 and C2 may be set in accordance with the relationship between the generated damping force and the current. That is, if the line indicating the relationship between the generated damping force of the shock absorber 2 and the current has a bending point in the middle, the output possible lines C1 and C2 are also indicated by broken lines having a bending point in the middle. If the line indicating the relationship between the generated damping force 2 and the current is a curve, the output possible lines C1 and C2 are also indicated by the curve.

  As described above, the shock absorber 2 is a passive shock absorber and cannot generate a thrust spontaneously. Therefore, when the direction of the target damping force is the same as the expansion and contraction direction of the shock absorber 2, the shock absorber 2. Cannot exert a damping force in the same direction as the target damping force, and it is necessary to make the damping force generated by the shock absorber 2 as small as possible. Therefore, in order to minimize the damping force of the shock absorber 2, the target current command value is set to 0 in this embodiment. That is, the output lower limit lines A1 and A2 are constant at 0 in this case.

  Further, when the direction of the target damping force is opposite to the expansion / contraction direction of the shock absorber 2 and exceeds the upper limit of the damping force output of the shock absorber 2, the generated damping force of the shock absorber 2 follows the target damping force. However, in order to maximize the damping force of the shock absorber 2, the target current command value is set to a predetermined upper limit value in order to maximize the damping force of the shock absorber 2. And That is, in this case, the output upper limit lines B1 and B2 are constant at the upper limit value of the current value on the hardware.

  When the direction of the target damping force is opposite to the expansion / contraction direction of the shock absorber 2 and the target damping force is within the output range of the shock absorber 2, the target damping force is set to the target damping force as described above. On the other hand, the target current command value has a one-to-one relationship, the target current command value is proportional to the target damping force, and the output possible lines C1 and C2 are proportional to the target damping force with a certain inclination. The inclinations of the output possible lines C1 and C2 are determined depending on the relationship between the amount of current supplied to the damping force adjusting mechanism 3 and the damping force in the shock absorber 2 while the slope with respect to the target damping force axis is constant.

  In the case of a shock absorber using an electrorheological fluid, the vertical axis in the contraction side map M1 and the expansion side map M2 is set as the target voltage command value, and the control device 4 is configured to obtain the target voltage command value from the target damping force. That's fine. Further, when the damping force adjusting mechanism 3 is a solenoid valve and the shock absorber 2 generates the maximum damping force when no current is supplied, the output lower limit lines A1 and A2 are set to the upper limit values of the current values on the hardware. And the output upper limit lines B1 and B2 may be constant at 0.

  In the case of this embodiment, the target current command value is described as the current value supplied to the damping force adjustment mechanism 3 itself. However, for example, when the coil 26 of the damping force adjustment mechanism 3 is PWM-controlled, the target current command value is The current command value is obtained as a duty ratio that has a one-to-one relationship with the supply current value, and the target current command value that is the duty ratio is given to the driver 45 that applies the PWM pulse voltage to the coil 26, so that the damping force adjusting mechanism 3 You may make it control the supply current to. Further, the driver may be provided on the damping force adjusting mechanism 3 side instead of being provided on the control device 4 side.

  Further, in this example, the contraction side map M1 and the expansion side map M2 are provided, but if the attenuation characteristics are the same on the expansion side and the contraction side, the maps are made one and the absolute value of the target damping force is obtained. On the other hand, a target current command value or a target voltage command value may be obtained.

  Further, in the above description, the damping coefficient of the shock absorber 2 changes depending on the amount of current applied to the damping force adjusting mechanism 3, and the target damping force is obtained by subtracting the minimum damping force from the required damping force. Therefore, it is only necessary to have the contraction side map M1 and the expansion side map M2, and the map calculation is simplified, but the target current command value or the target voltage command value is used as the required damping force as described above. Is obtained by mapping a three-dimensional graph of the relationship between the target damping force and the target current command value or the target voltage command value according to the expansion / contraction speed of the shock absorber 2, and using the three-dimensional map. Alternatively, a map of the target damping force and the target current command value or the target voltage command value created with respect to the expansion / contraction speeds of the plurality of shock absorbers 2 is stored, and the map corresponding to the expansion / contraction speed of the shock absorber 2 It may be obtained target current command value or target voltage command value by interpolating.

  In addition, the correction | amendment part 43 is arrange | positioned in the back | latter stage of the target current command value calculating part 44 which calculates | requires a target current command value, and the command (current) given to the damping force adjustment mechanism 3 is corrected by correcting the target current command value. Alternatively, the predetermined speed may be changed according to the magnitude of the target current command value as in the case of changing according to the target damping force as described above.

As can be understood from the above description, according to the suspension device 1 of the present embodiment, the target damping force after correction is kept within the possible damping force range of the shock absorber 2 by correcting the target damping force. , The change in the damping force generated by the shock absorber 2 when the expansion speed x of the shock absorber 2 is 0 and the predetermined speed V _p1 can be reduced, and when the expansion speed x of the shock absorber 2 exceeds the speed threshold V _p2 , After that, when the expansion / contraction speed x starts to decrease and becomes 0, the generated damping force change is relaxed by the speed threshold V _p2 exceeding the predetermined speed V _p1 and the difference β, and in the range from the difference β to the expansion / contraction speed x is 0. Since the generated damping force is corrected to be minimized, the command to the damping force adjusting mechanism 3 is changed to a value that minimizes the generated damping force of the shock absorber 2 from an early stage. Change in actual current flowing through mechanism 3 Even late, when the expansion rate x of the damper 2 is 0, the actual current flowing through the damping force adjusting mechanism 3 can be made zero.

  Thus, since the current does not remain in the damping force adjusting mechanism 3 when the expansion / contraction speed x of the shock absorber 2 is switched between 0 and 0, the shock absorber does not exhibit an unintended damping force. The damping force does not change suddenly when the expansion / contraction speed of the shock absorber 2 is near 0, and the riding comfort in the vehicle is not deteriorated. Therefore, according to the suspension device 1 of the present invention, the sudden change of the damping force generated by the shock absorber can be reliably mitigated and the riding comfort in the vehicle can be improved.

  Further, in the suspension device 1 of the present embodiment, the corrected target damping force can be kept within the range of the damping force that can be generated by the shock absorber 2, so that it is not necessary to give a waste current to the damping force adjusting mechanism 3. Energy saving. That is, when the target damping force is not corrected, as shown by the broken line in FIG. 12, even if the expansion / contraction speed of the shock absorber is in the extremely low speed region, a current amount that is one-to-one with the target damping force is output to the damping force adjusting mechanism. However, in the suspension device 1 according to the present embodiment, as shown by the solid line in FIG. 12, the corrected target damping force can be within the range of the damping force that can be generated by the shock absorber 2. It is not necessary to give a waste current to the adjusting mechanism 3. The corrected target damping force in FIG. 12 shows a case where the target damping force causes the shock absorber 2 to generate a damping force in the extension direction. However, the target damping force is applied to the shock absorber 2 in the contracting direction. When the damping force is generated, the solid line is rotated 180 degrees around the origin, and even if the target damping force causes the shock absorber 2 to generate a damping force in the contraction direction, it is corrected. Naturally, the target damping force can be kept within the range of the damping force that can be generated by the shock absorber 2.

Further, the rate of change of the command to the corrected damping force adjusting mechanism 3 is such that when the expansion / contraction speed of the shock absorber 2 is in the range from 0 to a half of the predetermined speed V _p1 , When the expansion / contraction speed of the shock absorber 2 is in the range of the predetermined speed V _p1 exceeding the half of the predetermined threshold value V _p1 , the expansion speed of the shock absorber 2 is increased (decreased) gradually. Since it gradually decreases as the speed increases, there is no sudden change in acceleration to the vehicle body. Further, even if the expansion / contraction speed x exceeds the speed threshold value _Vp2 , the rate of change of the command is the expansion / contraction speed of the shock absorber 2. When x exceeds β + V _p1 / 2 and is in the range of the speed threshold value V _p2 , the expansion / contraction speed x of the shock absorber 2 gradually decreases (increases) as the expansion / contraction speed of the shock absorber 2 increases (decreases). when from a range of β _{+ V p1} / 2 is slow Because gradually increases (decreases) with an increase in the stretch rate of vessel 2 (decreasing), even in this case, never give sudden acceleration changes to the vehicle body.

Further, in this case, since the correction coefficient α is calculated by the above equation, the attenuation characteristic and the expansion / contraction of the shock absorber 2 when the expansion / contraction speed of the shock absorber 2 is in the range from 0 to a half of the predetermined speed V _p1. speed leads to smooth and damping characteristics are continuous when the range of the predetermined speed V _p1 the half-beyond the predetermined speed V _p1, stretching speed x of the shock absorber 2 is beyond the beta + V _{p1 / 2} speed Since the damping characteristic when it is in the range of the threshold value V _p2 and the damping characteristic when the expansion / contraction speed x of the shock absorber 2 is in the range of β to β + V _p1 / 2 are continuously connected smoothly and smoothly, The effect of not giving a change in acceleration can be enhanced.

In calculating the correction coefficient α, when the expansion / contraction speed x of the shock absorber 2 is in the range of 0 to V _p1 / 2, the correction coefficient α is set to α = − (V _p1 ² −4x ² ) ^1/2 / 2V. _p1 +1/2 is calculated, and when the expansion / contraction speed of the shock absorber 2 exceeds V _p1 / 2 and falls within the predetermined speed V _p1 , the correction coefficient α is set to α = {V _p1 ² -4 (x-4V ^{_{p1) 2} 1/2 / 2V p1}} +1/2 may be obtained by calculating the. When the expansion / contraction speed x of the shock absorber 2 exceeds the speed threshold value and the expansion / contraction speed x of the shock absorber 2 is in the range of β to V _p2 −V _p1 / 2, the correction coefficient α is set to α = α = − {V _p1 ² -4 (x−β) ² } ^1/2 / 2V _p1 +1/2 is calculated and the expansion / contraction speed x of the shock absorber 2 is changed from V _p2 −V _p1 / 2 to the x speed threshold value V _p2. Is within the range, the correction coefficient α may be obtained by calculating α = [V _p1 ² -4 {(x−β) -4V _p1 } ² ] ^1/2 / 2V _p1 +1/2. Good.

In this case, the corrected target damping force changes so as to follow the trajectory of a circle having two tangent radii V _p1 / 2. However, even if calculated in this way, the damping characteristic is continuous. Connected smoothly and does not shock the car body.

In addition to the above, for calculating the correction coefficient α, a map for calculating the correction coefficient may be used in advance, or the expansion / contraction speed x of the shock absorber 2 may be set to 0 using a trigonometric function or a hyperbolic function. Although the change in the damping force generated by the shock absorber 2 at the speed V _p1 , the difference β, and the speed threshold value V _p2 may be alleviated, the calculation load is smaller when the correction coefficient α is calculated by a quadratic function. The load on the arithmetic device such as a CPU that implements each part of the device 4 can be reduced, and an inexpensive arithmetic device can be used, thereby reducing the cost of the suspension device 1. In addition, in calculating the correction coefficient α, there is an advantage that the calculation load can be further reduced because the above-described arithmetic expression is used and it is not necessary to perform route calculation.

In the suspension device 1 of the present embodiment, a steep change in the damping force can be suppressed as described above, but the target damping force becomes a large value exceeding the maximum damping force of the shock absorber 2 in the first place, and the correction unit 43. If the target damping force after the correction exceeds the maximum damping force of the shock absorber 2 even if it is corrected by the above, the damping force at the time when the expansion / contraction speed x of the shock absorber 2 becomes the predetermined speed V _p1 and the speed threshold value V _p2 In some cases, the effect of suppressing the steep change is weakened. This is because when the target damping force is excessive, even if the target damping force is multiplied by the correction coefficient α, the maximum damping force of the shock absorber 2 is exceeded, and the expansion / contraction speed x of the shock absorber 2 becomes the predetermined speed V _p1. This is because it becomes difficult to effectively mitigate the change in the damping force generated by the shock absorber 2 at the time when the speed threshold _Vp2 is reached. Therefore, the suspension device 1 of the present embodiment includes a limiter 42 that performs a limiter process for clamping the target damping force calculated by the target damping force calculation unit 41 to a limit value. Specifically, the limiter 42 limits the target damping force to a value corresponding to the maximum damping force of the shock absorber 2 in this case. In this way, the limiter 42 limits the target damping force to the maximum value obtained by subtracting the minimum damping force from the maximum damping force of the shock absorber 2. Therefore, when the target damping force is corrected by the correction coefficient α in the correction unit 43, The corrected target damping force is always within the range of the damping force that can be generated by the shock absorber 2, and the generated damping force of the shock absorber 2 at the time when the expansion / contraction speed x of the shock absorber 2 becomes the predetermined speed V _p1 and the speed threshold value V _p2 . Change can be mitigated. Note that when the target current command value calculation unit 44 obtains the target current command value from the target damping force without performing this limiter process, consideration is given so that the target current command value does not exceed the maximum value on the hardware. The target current command value calculation unit 44 itself functions as a limiter in a broad sense. However, by using the limiter 42 and correcting the target damping force with the correction unit 43 as a correction unit, the expansion / contraction speed x of the shock absorber 2 is predetermined. This is significant in that the change in the generated damping force at the time when the speed V _p1 and the speed threshold value V _p2 are reached can be moderated.

  Next, suspension devices according to other embodiments will be described. In the suspension device according to the other embodiment, the map used in the target current command value calculation unit 44 is different from the suspension device 1 according to the one embodiment. Therefore, the system configuration of the suspension apparatus in the other embodiments is the same as that of the suspension apparatus 1 in the embodiment shown in FIG.

  Therefore, even in the suspension device according to another embodiment, the target damping force is corrected, the target current command value is obtained from the corrected target damping force, and the amount of current supplied to the damping force adjusting mechanism 3 is adjusted. Thus, the effect of correcting the target damping force is the same as that of the suspension device 1 according to the embodiment.

  Hereinafter, in order to avoid duplication of description, description of the same part as the suspension device 1 in the embodiment will be omitted, and different parts will be described in detail.

  Subsequently, a map used in the target current command value calculation unit 44 in the suspension device according to another embodiment will be described. The target current value command value calculation unit 44 performs map calculation for obtaining a target current command value from the target damping force corrected by the correction unit 43 using a map, and outputs the target current command value to the driver 45.

There are two maps used for the map calculation. Specifically, the contraction side map M3 used when the shock absorber 2 operates to expand and the expansion side used when the shock absorber 2 operates to contract. There is a map M4. That is, a map is prepared for each expansion / contraction direction of the shock absorber 2. As shown in FIG. 13, the contraction-side map M3 corresponds to the case where the shock absorber 2 is contracting and the target damping force instructs the shock absorber 2 to generate a damping force in the contracting direction. Corresponding to the output lower limit line A3 that takes a constant value with respect to the change, and when the shock absorber 2 is contracted and the target damping force instructs the shock absorber 2 to generate a damping force in the extension direction, but exceeds the output upper limit. The output upper limit line B3 that takes a constant value with respect to the change in the target damping force, the output lower limit line A3, and the output upper limit line B3 are connected, and the shock absorber 2 is contracted, so that the target damping force is applied to the shock absorber 2. Corresponding to the case where the generation of the damping force in the extending direction is instructed and within the output possible range, the output possible line C3 that changes in proportion to the target damping force, the output possible line C3, and the output lower limit line A3 Mitigation line D3 connecting the two and output possible And a relaxation line E3 connecting the in-C3 and the output upper limit line B3. On the other hand, as shown in FIG. 14, the extension side map M4 corresponds to a case where the shock absorber 2 is extended and the target damping force instructs the shock absorber 2 to generate a damping force in the extension direction. The output lower limit line A4 that takes a constant value with respect to the change of the damping force, and the shock absorber 2 is extended, and the target damping force instructs the shock absorber 2 to generate the damping force in the contraction direction, but exceeds the output upper limit. Corresponding to the case, the output upper limit line B4 that takes a constant value with respect to the change of the target damping force, the output lower limit line A4, and the output upper limit line B4 are connected, and the shock absorber 2 is extended so that the target damping force is buffered. The output possible line C4 which changes in proportion to the target damping force corresponding to the case where the generator 2 is instructed to generate the damping force in the contraction direction and is within the output possible range, the output possible line C4 and the output lower limit line A relaxation line D4 connecting between A4 and A4; And a relaxation line E4 which connects between the force possible line C4 and the output limit line B4. In the contraction side map M3 and the expansion side map M4, the target damping force is a positive value that causes the shock absorber 2 to generate a damping force in the expansion direction, that is, the target damping force that causes the shock absorber 2 to exert a damping force that prevents contraction. The force value is positive, and the target damping force that generates damping force in the opposite direction is negative. In this embodiment, the target current command value is 0 or more regardless of the direction of the target damping force because the damping coefficient is adjusted by supplying current to the damping force adjusting mechanism 3. . In the above description, when the target damping force is within the output possible range of the shock absorber 2, the current applied to the damping force adjusting mechanism 3 and the generated damping force of the shock absorber 2 are in a proportional relationship. The output possible lines C1 and C2 in the expansion side map M2 are linear because the target current command value changes proportionally according to the current value target damping force, but the relationship between the generated damping force of the shock absorber 2 and the current Is non-linear, the output possible lines C1 and C2 may be set in accordance with the relationship between the generated damping force and the current. That is, if the line indicating the relationship between the generated damping force of the shock absorber 2 and the current has a bending point in the middle, the output possible lines C1 and C2 are also indicated by broken lines having a bending point in the middle. If the line indicating the relationship between the generated damping force 2 and the current is a curve, the output possible lines C1 and C2 are also indicated by the curve.

  Here, since the shock absorber 2 is a passive shock absorber and cannot generate a thrust spontaneously, when the direction of the target damping force is the same direction as the expansion and contraction direction of the shock absorber 2, the shock absorber 2 is Since the damping force cannot be exhibited in the same direction as the target damping force, it is necessary to reduce the damping force generated by the shock absorber 2 as much as possible. Therefore, in order to minimize the damping force of the shock absorber 2, the target current command value is set to 0 in this embodiment. That is, the output lower limit lines A3 and A4 are constant at 0 in this case.

  Further, when the direction of the target damping force is opposite to the expansion / contraction direction of the shock absorber 2 and exceeds the upper limit of the damping force output of the shock absorber 2, the generated damping force of the shock absorber 2 follows the target damping force. However, in order to maximize the damping force of the shock absorber 2, the target current command value is set to a predetermined upper limit value in order to maximize the damping force of the shock absorber 2. To do. That is, in this case, the output upper limit lines B3 and B4 are constant at the upper limit value of the current value on the hardware.

  When the direction of the target damping force is opposite to the expansion / contraction direction of the shock absorber 2 and the target damping force is within the output range of the shock absorber 2, the target damping force is set to the target damping force as described above. On the other hand, the target current command value has a one-to-one relationship, the target current command value is proportional to the target damping force, and the output possible lines C3 and C4 are proportional to the target damping force with a certain inclination. The inclinations of the output possible lines C3 and C4 are determined depending on the relationship between the amount of current supplied to the damping force adjusting mechanism 3 and the damping force in the shock absorber 2 while the slope with respect to the target damping force axis is constant.

  In the case of a shock absorber using an electrorheological fluid, the vertical axis in the contraction side map M3 and the expansion side map M4 is the target voltage command value, and the control device 4 is configured to obtain the target voltage command value from the target damping force. That's fine. Further, when the damping force adjusting mechanism 3 is a solenoid valve and the shock absorber 2 generates the maximum damping force when no current is supplied, the output lower limit lines A3 and A4 are set to the upper limit value of the current value on the hardware. And the output upper limit lines B3 and B4 may be constant at 0.

  For example, when the coil 26 of the damping force adjusting mechanism 3 is subjected to PWM control, the target current command value is obtained as a duty ratio that has a one-to-one relationship with the supply current value, and is supplied to the driver 43 that applies the PWM pulse voltage to the coil 26. The supply current to the damping force adjusting mechanism 3 may be controlled by giving a target current command value that is a duty ratio. Further, the driver may be provided on the damping force adjusting mechanism 3 side instead of being provided on the control device 4 side. Further, the target current command value may be the current value itself supplied to the damping force adjusting mechanism 3.

  In the contraction side map M3, the relaxation line D3 is connected to the output lower limit line A3 with a smaller slope than the output possible line C3, and the output possible line C3 is connected to the output lower limit line A3 in FIG. As shown by the middle broken line, the change in the target current command value across the intersection P1 with the output lower limit line A3 is alleviated as compared with the case where the connection is made without changing the inclination directly. In the contraction side map M3, the relaxation line E3 is connected to the output upper limit line B3 with a smaller slope than the output possible line C3, and the output possible line C3 is connected to the output upper limit line B3 in FIG. As shown by the middle broken line, the change in the target current command value across the intersection Q1 with the output upper limit line B3 is alleviated as compared with the case where the connection is made without changing the inclination directly.

  Further, also in the expansion side map M4, the relaxation line D4 is connected to the output lower limit line A4 with a smaller slope than the output possible line C4, and the output possible line C2 is connected to the output lower limit line A4. Compared with the case where the connection is made without changing the inclination directly as shown by the broken line in FIG. 14, the change in the target current command value across the intersection P2 with the output lower limit line A4 is alleviated. Also in the expansion side map M4, the relaxation line E4 is connected to the output upper limit line B4 with a smaller slope than the output possible line C4, and the output possible line C4 is connected to the output upper limit line B4. Compared with the case where the connection is made without changing the inclination directly as shown by the broken line in FIG. 14, the change in the target current command value across the intersection Q2 with the output upper limit line B4 is alleviated.

  Thus, in the contraction side map M3 and the expansion side map M4 for obtaining the target current command value for determining the amount of current to be supplied from the target damping force to the damping force adjusting mechanism 3, the relaxation lines D3, D4, E3, E4 are Because it is provided, the target damping force changes from the damping force output range (output possible range) of the shock absorber 2 to the range where output is impossible (output impossible range), or from the output impossible range to output possible range. In this case, since the amount of change in the target current command value is alleviated, a sudden change in the damping force generated by the shock absorber 2 can be suppressed, and the vehicle vibration can be effectively suppressed to improve the riding comfort in the vehicle. Can do. That is, in the suspension device according to another embodiment, by correcting the target damping force, not only can the sudden change in the damping force of the shock absorber 2 with respect to the expansion / contraction speed of the shock absorber 2 be reduced, but also the change in the target damping force. It is possible to mitigate sudden changes in the damping force with respect to.

  Although the relaxation lines D3, D4, E3, and E4 are straight lines having a certain slope as described above, the slope gradually changes, and the output possible lines C3 and C4 and the output lower limit line A3. , A4 and the output upper limit lines B3, B4 may be smoothly connected. In other words, the relaxation lines D3, D4, E3, and E4 are arc-shaped lines that gradually decrease from the inclination of the output possible lines C3 and C4 and smoothly connect to the output lower limit lines A3 and A4 and the output upper limit lines B3 and B4. It may be said. In addition, the inclination, shape, and length of the relaxation line D3 and the relaxation line E3 are both the same, but may be set to be different. The same applies to the inclination, shape, and length of the relaxation line D4 and the relaxation line E4. May be different. Further, the line shape in the contraction side map M3 and the expansion side map M4 (shape connecting the output lower limit lines A3, A4, the output upper limit lines B3, B4, the output possible lines C3, D4 and the relaxation lines D3, D4, E3, E4) Is a line-symmetric shape with respect to the target current command value axis, but is not limited to this.

  Further, in this example, the contraction side map M3 and the expansion side map M4 are provided. However, if the attenuation characteristics are the same on the expansion side and the contraction side, the maps are made one and the absolute value of the target damping force is obtained. On the other hand, a target current command value or a target voltage command value may be obtained.

  Further, in the above description, the damping coefficient of the shock absorber 2 changes depending on the amount of current applied to the damping force adjusting mechanism 3, and the target damping force is obtained by subtracting the minimum damping force from the required damping force. Therefore, it is only necessary to have the contraction side map M3 and the expansion side map M4, and the map calculation is simplified. However, the target damping force is the target current command value or the target voltage command value as the necessary damping force as described above. May be obtained using a three-dimensional map in which the relationship between the target damping force and the target current command value or the target voltage command value is determined in accordance with the expansion / contraction speed of the shock absorber 2. A map of the target damping force and the target current command value or target voltage command value created for the expansion / contraction speed of the shock absorber 2 is retained, and the target current is complemented between the maps according to the expansion / contraction speed of the shock absorber 2 It may be obtained decree value or target voltage command value.

  By the way, the relaxation lines D3 and D4 are smaller in inclination than the output possible lines C3 and C4, so that the output possible lines C3 and C4 do not change the inclination, and the relaxation lines are at the virtual intersections R1 and R2 that intersect the output lower limit lines A3 and A4. When D3 and D4 are connected, they do not intersect with the output possible lines C3 and C4, so the line segment is above the virtual intersections R1 and R2. That is, when the relaxation lines D3 and D4 are provided, the target current command value takes a certain positive value when the target damping force is zero.

  Among these, in the relaxation lines D3 and D4, when the target damping force is in the vicinity of 0 and the direction of the target damping force and the expansion / contraction direction of the shock absorber 2 are different, the target current command value takes a positive value. Therefore, the shock absorber 2 outputs a damping force although it is small. If the influence of the damping force on the riding comfort cannot be ignored, the relaxation lines D3 and D4 may be eliminated. Further, after providing the relaxation lines D3 and D4 and obtaining the target current command value from the target damping force, the gain that takes a value of 0 when the expansion / contraction speed of the shock absorber 2 is within the speed affected by the relaxation lines D3 and D4. To reduce the influence of the relaxation lines D3 and D4 on the riding comfort when the target damping force is in the vicinity of zero. In the case of using the gain, the relaxation lines D3 and D4 need not be eliminated, but the influence of the relaxation lines D3 and D4 may be eliminated only for the portion that causes the deterioration of the ride comfort. It is possible to prevent the ride comfort from deteriorating while taking advantage of the above-described advantages. As a method of providing the gain, for example, the gain in the range where the relaxation lines D3 and D4 are not desired to be applied depending on the expansion / contraction speed of the shock absorber 2 may be set to 0, and the other range may be set to 1, as shown in FIG. In addition, the gain may be gradually changed in a ramp manner instead of stepwise from 0 to 1. The change in the damping force of the shock absorber 2 can be smoothed by changing the ramp. In the case where the damping force adjusting mechanism 3 is a solenoid valve and the shock absorber 2 generates the maximum damping force when no current is supplied, the relaxation lines E3 and E4 connected to the output upper limit lines B3 and B4 The influence should be removed.

  Even in the suspension device according to another embodiment, the limiter 42 can be omitted as in the suspension device 1 according to the above-described one embodiment. However, when the limiter 42 is provided, the target damping force is reduced. The limit value to be limited is set to the target damping force at the intersection where the relaxation lines D3 and D4 connect to the output upper limit lines B3 and B4. By providing the relaxation lines E3 and E4, as shown in FIGS. 13 and 14, the target current command value is maximized when the target damping force exceeds the maximum damping force on the hardware of the shock absorber 2. Therefore, the limit value of the limiter 42 may be a target damping force that maximizes the target current command value.

In this way, even in the suspension device according to another embodiment, as in the suspension device 1 according to one embodiment, the limiter 42 is installed to limit the target damping force, and then the correction unit 43 If the correction is made, the corrected target damping force is almost within the range of the damping force that can be generated by the shock absorber 2, and the shock absorber 2 generates at the predetermined speed V _p1 and the speed threshold V _p2 when the expansion / contraction speed of the shock absorber 2 is the predetermined speed V _p1. The change of the damping force can be moderated with certainty.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

  The vehicular shock absorber of the present invention can be used for vibration control of a vehicle.

DESCRIPTION OF SYMBOLS 1 Suspension apparatus 2 Shock absorber 20 Cylinder 21 Piston 22 Piston rods 23 and 24 Pressure chamber 25 Passage 26 Coil 3 Damping force adjustment mechanism 4 Control device 41 Target damping force calculation part 42 Limiter 43 Correction part 44 Target current command value calculation part 45 Driver 5 Acceleration sensor 6 Stroke sensor A1, A2, A3, A4 Output lower limit line B1, B2, B3, B4 Output upper limit line C1, C2, C3, C4 Output possible line D3, D4, E3, E4 Relaxation line M1, M3 Contraction side Map M2, M4 Expansion side map

Claims (6)

A shock absorber that is interposed between the vehicle body and the wheel in the vehicle to suppress the relative movement of the vehicle body and the wheel in the vertical direction, a damping force adjustment mechanism that adjusts the damping force, and a target damping force And a control device for controlling the damping force adjusting mechanism based on the control device, wherein the control device relaxes a change in the damping force generated by the shock absorber when the expansion speed of the shock absorber is zero and a predetermined speed. And the correction means sets the expansion / contraction speed for relaxing the generated damping force change until the expansion / contraction speed becomes zero when the expansion / contraction speed of the shock absorber exceeds a speed threshold set to a value exceeding the predetermined speed. The generated damping force is corrected by offsetting toward the speed increasing side by the difference between the speed threshold and the predetermined speed, and the generated damping force is corrected to be minimized until the expansion / contraction speed is zero from the difference. Scan pension system. 2. The suspension apparatus according to claim 1, wherein the correction means corrects the generated damping force by multiplying a command given to the damping force adjusting mechanism by a correction coefficient obtained from the expansion / contraction speed of the shock absorber. When the predetermined speed is V _p1 , the speed threshold is V _p2 , the difference between the speed threshold obtained by subtracting the predetermined speed from the speed threshold and the predetermined speed is β, and the expansion / contraction speed of the shock absorber is x, the correction The means does not satisfy x> V _p2 , x ≦ V _p1 , 0 ≦ x ≦ V _p1 / 2 and V _p1 / 2 <x ≦ V _p1. When a correction coefficient is calculated using a function and x> V _p2 is satisfied, until 0 is satisfied, β ≦ x ≦ V _p2 −V _p1 / 2 and V _p2 −V _p1 / 2 <x ≦ V _p2 The suspension apparatus according to claim 1 or 2, wherein the correction coefficient is calculated using a quadratic function corresponding to each of the cases, and the correction coefficient in 0 ≦ x <β is set to 0. . When the predetermined speed is V _p1 , the speed threshold is V _p2 , the difference between the speed threshold obtained by subtracting the predetermined speed from the speed threshold and the predetermined speed is β, and the expansion / contraction speed of the shock absorber is x, the correction means, in the case of x ≦ _{V p1} not satisfy the _{x> V p2,} 0 in the case of ≦ x ≦ _{V p1} / 2 is determined by calculating the correction coefficient _{^{α α = 2x 2 / V p1}} 2, V p1 / 2 <x ≦ V _p1 , the correction coefficient α is calculated by calculating α = −2 (x−V _p1 ) ² / V _p1 ² +1 until x> V _p2 is satisfied until 0 is satisfied. , Β ≦ x ≦ V _p2 −V _p1 / 2, the correction coefficient α is obtained by calculating α = 2 (x−β) ² / V _p1 ² , and V _p2 −V _p1 / 2 <x ≦ 0 with the case of V _p2 obtains a correction coefficient α α = -2 (x-β -V p1) by calculating a _{2 / V} ^p1 ₂ +1 The suspension device according to any one of claims 1 to 3, the definitive correction coefficient of x <beta characterized by zero. The control device includes a limiter unit that performs a limiter process that clamps the command to a limit value, calculates a correction coefficient after performing the limiter process of the command, and the correction unit corrects the command after the limiter process. The suspension device according to any one of claims 1 to 4, wherein The suspension device according to any one of claims 1 to 5, wherein the predetermined speed and the speed threshold value change according to a target damping force obtained by the control device.

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