JP2012111326A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device that can relax a sudden change of generated damping force of a shock absorber, and can improve degree of comfort in a vehicle.SOLUTION: A target current command value given to a damping force adjusting mechanism which adjusts the damping force of the shock absorber is computed by using: an output lower limit line A1 which takes a constant value to a change of a target damping force corresponding to the case when the direction of target damping force is the same direction with the flexible direction of the shock absorber; an output upper limit line B1 which takes a constant value to a change of the target damping force corresponding to the case when the direction of target damping force exceeds the output upper limit although the flexible directions of the shock absorber differs; an output possible line C1 which proportionally changes to the target damping force corresponding to the case when the direction of target damping force differ from the flexible direction of the shock absorber and the shock absorber can output; and a map equipped with relaxation lines D1 and E1 which connect an output possible line and an output lower limit line, and an output possible line and an output upper limit line.

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).

  In this suspension device, the control device obtains the skyhook control force, obtains a deviation between the skyhook control force and the minimum damping force that can be generated by the shock absorber, and sets the deviation as a target damping force. A target current value to be given from the target damping force to the damping force adjusting mechanism is obtained using a corresponding target current value map. If the sign of the product of the target damping force and the stroke speed of the shock absorber is negative, the target damping force is set to 0 and the target current value is obtained.

  In the map, the target current value changes in proportion to the change of the target damping force. When the target damping force is 0, the target current value is limited to the maximum value, and the absolute value of the target damping force is When the value exceeds the maximum damping force of the shock absorber, the target current value becomes 0 which is a limit value.

  In other words, when the target damping force cannot be output from the expansion / contraction direction of the shock absorber and when the target damping force is lower than the minimum damping force of the shock absorber, the control device sets the target current to cause the shock absorber to exert the minimum damping force. When the target damping force exceeds the maximum damping force of the shock absorber, the target current value is set to 0 so that the shock absorber can exert the maximum damping force. If the target damping force is between the minimum current value and the maximum current value, the target current value proportional to the target damping force is output to the damping force adjustment mechanism, so that the skyhook is applied to the shock absorber. The damping force in accordance with the control theory is exhibited to improve the riding comfort in the vehicle.

JP 2008-12959 A

  However, in the suspension device disclosed in Japanese Patent Application Laid-Open No. 2008-12959, the target damping force varies proportionally when the target damping force is within the output possible range of the shock absorber, but the target damping force is within the output impossible range of the shock absorber. The target current value suddenly changes and the damping force generated by the shock absorber suddenly changes when the target damping force changes from the shockable output range of the shock absorber to the power impossible range. As a result, the vehicle body vibration cannot be effectively suppressed, and there is a problem that the riding comfort of the vehicle is deteriorated.

  Accordingly, the present invention has been developed to improve the above-described problems, and the object of the present invention is to alleviate a sudden change in the damping force generated by the shock absorber and improve the riding comfort in the vehicle. It is to provide a suspension device that can be used.

  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 in the shock absorber according to the supplied current amount or voltage, and a control device that controls the damping force adjusting mechanism. Using the target current command value or target voltage command value map corresponding to the force, the target current command value or target voltage command value to be given from the target damping force to the damping force adjusting mechanism is obtained. Corresponding to the case where the direction is the same as the expansion / contraction direction of the shock absorber, an output lower limit line that takes a constant value with respect to the change in the target damping force, and output of the target damping force that differs from the expansion / contraction direction of the shock absorber. The output upper limit line that takes a constant value with respect to the change in the target damping force in response to exceeding the upper limit is connected to the output lower limit line and the output upper limit line, and the direction of the target damping force is different from the expansion / contraction direction of the shock absorber. Corresponding to the case where the shock absorber can output, it has an output possible line that changes according to the target damping force, and the output possible line is more inclined than the output possible line with respect to one or both of the output lower limit line and the output upper limit line It is connected via a small relaxation line.

  According to the suspension device of the present invention, since the relaxation line is provided in the map for obtaining the target current command value for determining the amount of current supplied from the target damping force to the damping force adjusting mechanism, the target damping force can be output from the buffer. The amount of change in the target current command value is alleviated when there is a change from the range where the damping force cannot be output to the range where output is impossible, or from the range where output is impossible to within the range where output is possible. Sudden changes can be suppressed, vehicle vibrations can be effectively suppressed, and riding comfort in the vehicle can be improved.

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 explaining the shrinkage | contraction side map of the suspension apparatus in one Embodiment. It is a figure explaining the expansion | extension side map of the suspension apparatus in one Embodiment. It is a figure explaining the gain which multiplies the target current command value or target voltage command value of the suspension apparatus in one embodiment.

  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. The same applies to 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, and the flow path is changed 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. The motor is configured to include a motor and a motion conversion mechanism that returns the rotational motion of the motor to linear motion, or is 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, the control device 4 controls the damping force of the shock absorber 2 in accordance with the skyhook control side. Therefore, the control device 4 includes an acceleration sensor 5 that detects the vertical acceleration of the vehicle body, A stroke sensor 6 is provided for detecting the expansion / contraction speed of the shock absorber 2. Furthermore, the control device 4 includes a target damping force calculation unit 41 and a map calculation unit 42 that obtains a target current command value by map calculation. Note that the target damping force calculation unit 41 and the map calculation unit 42 in the control device 4 are not shown, but specifically, for example, a ROM (Read) that stores a program used for processing necessary for controlling the shock absorber 2. A storage device such as an Only Memory), an arithmetic device such as a CPU (Central Processing Unit) that executes processing based on the program, and a storage device such as a RAM (Random Access Memory) that provides a storage area for the CPU. The units 41 and 42 are realized by the CPU executing the program.

  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 region, 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 current amount have a one-to-one relationship. That is, when the target damping force is obtained, the current amount 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. Note that the control device 4 may receive an input of the target damping force from an upper control device (not shown).

  Subsequently, the map calculation unit 42 in the control device 4 performs a map calculation for obtaining a target current command value from the target damping force, and outputs the target current command value to the driver 43. The driver 43 outputs a current amount corresponding to the target current command value 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.

There are two maps used for the map calculation in the map calculation unit 42. Specifically, when the shock absorber 2 is contracted, the contraction side map M1 is used, and when the shock absorber 2 is contracted. There is a decompression map M2 used. That is, a map is prepared for each expansion / contraction direction of the shock absorber 2. As shown in FIG. 5, the contraction-side map M <b> 1 shows that the target damping force is in 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 contracted in the shock absorber 2. Corresponding to the case where the generation of the damping force 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 (the damping that the target damping force instructs the buffer 2) Force generation direction) exceeds the upper limit of the output of the shock absorber 2 with different expansion / contraction directions, that is, 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. Is connected to the output upper limit line B1, which takes a constant value with respect to the change in the target damping force, and the output lower limit line A1 and the output upper limit line B1, and the direction of the target damping force is a buffer. Shock absorber 2 can output with different expansion / contraction direction In other words, the shock absorber 2 is contracted, the target damping force instructs the shock absorber 2 to generate a damping force in the extension direction, and is proportional to the target damping force corresponding to the output possible range. Output possible line C1 changing, output possible line C1 and relaxation line D1 connecting between output lower limit line A1 and relaxation line E1 connecting between output possible line C1 and output upper limit line B1 are provided. ing. On the other hand, as shown in FIG. 6, the extension side map M2 has a direction in which 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 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 which changes in proportion to the target damping force 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 in the output possible range, and the output A mitigation line D2 connecting between the possible line C2 and the output lower limit line A2 and a mitigation line E2 connecting between the output possible line C2 and the output upper limit line B2 are provided. 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 a value of 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 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. To do. 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.

  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 M1, the relaxation line D1 is connected to the output lower limit line A1 with a smaller slope than the output possible line C1, and the output possible line C1 is connected to the output lower limit line A1 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 A1 is alleviated as compared with the case where the connection is made without directly changing the inclination. In the contraction side map M1, the relaxation line E1 is connected to the output upper limit line B1 with a smaller slope than the output possible line C1, and the output possible line C1 is connected to the output upper limit line B1 in FIG. As shown by the middle broken line, the change in the target current command value across the intersection point Q1 with the output upper limit line B1 is alleviated as compared with the case where connection is made without changing the inclination directly.

  Further, also in the expansion side map M2, the relaxation line D2 is connected to the output lower limit line A2 with a smaller slope than the output possible line C2, and the output possible line C2 is connected to the output lower limit line A2. Compared with the case where the connection is made without changing the inclination directly as shown by the broken line in FIG. 6, the change in the target current command value across the intersection P2 with the output lower limit line A2 is alleviated. Also in the expansion side map M2, the relaxation line E2 is connected to the output upper limit line B2 with a smaller slope than the output possible line C2, and the output possible line C2 is connected to the output upper limit line B2. The change in the target current command value across the intersection Q2 with the output upper limit line B2 is alleviated as compared with the case where the connection is made without changing the inclination directly as shown by the broken line in FIG.

  Thus, in the contraction side map M1 and the expansion side map M2 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 D1, D2, E1, and E2 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.

  Note that the relaxation lines D1, D2, E1, and E2 are straight lines having a certain inclination in the above description, but the inclination gradually changes to allow the output possible lines C1 and C2 and the output lower limit line A1. , A2 and the output upper limit lines B1 and B2 may be smoothly connected. That is, the relaxation lines D1, D2, E1, and E2 are arc-shaped lines that gradually decrease from the inclination of the output possible lines C1 and C2 and smoothly connect to the output lower limit lines A1 and A2 and the output upper limit lines B1 and B2. It may be said. In addition, the inclination, shape, and length of the relaxation line D1 and the relaxation line E1 are both the same, but may be set to be different. The same applies to the inclination, shape, and length of the relaxation line D2 and the relaxation line E2. May be different. Further, the line shape in the contraction side map M1 and the expansion side map M2 (shape connecting the output lower limit lines A1, A2, the output upper limit lines B1, B2, the output possible lines C1, D2 and the relaxation lines D1, D2, E1, E2) 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 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 complement.

  By the way, since the relaxation lines D1 and D2 have a smaller inclination than the output possible lines C1 and C2, the output possible lines C1 and C2 do not change the inclination, and the relaxation lines are at virtual intersections R1 and R2 that intersect the output lower limit lines A1 and A2. When D1 and D2 are connected, they do not intersect with the output possible lines C1 and C2, so the line segment is above the virtual intersections R1 and R2. That is, if the relaxation lines D1 and D2 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 D1 and D2, when the target damping force is in the vicinity of 0 and the direction of the target damping force is different from the expansion / contraction direction of the shock absorber 2, 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 D1 and D2 may be eliminated. Further, after the relaxation lines D1 and D2 are provided and the target current command value is obtained 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 D1 and D2. May be used to remove the influence of the relaxation lines D1 and D2 on the ride comfort when the target damping force is in the vicinity of zero. In the case of using the gain, the relaxation lines D1 and D2 need not be eliminated, but the influence of the relaxation lines D1 and D2 should 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 a range where the relaxation lines D1 and D2 are not desired to be effective depending on the expansion / contraction speed of the shock absorber 2 may be set to 0, and the range not to be set to 1 may be 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 buffer 2 generates the maximum damping force when no current is supplied, the relaxation lines E1 and E2 connected to the output upper limit lines B1 and B2 The influence should be removed.

  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 apparatus 41 Target damping force calculating part 42 Map calculating part 43 Driver 5 Acceleration sensor 6 Stroke sensor A1, A2 Output lower limit line B1, B2 Output upper limit line C1, C2 Output possible line D1, D2, E1, E2 Relaxation line M1 Contraction side map M2 Expansion side map

Claims (3)

A shock absorber that is interposed between the vehicle body and the wheel in the vehicle and exhibits a damping force that suppresses the relative movement in the vertical direction between the vehicle body and the wheel, and the attenuation in the shock absorber according to the supplied current amount or voltage In a suspension device including a damping force adjusting mechanism that adjusts a force and a control device that controls the damping force adjusting mechanism, the control device displays a map of a target current command value or a target voltage command value corresponding to the target damping force. The target current command value or target voltage command value given from the target damping force to the damping force adjusting mechanism is obtained, and the above map is prepared for each expansion / contraction direction of the shock absorber, and the direction of the target damping force is the expansion / contraction of the shock absorber. If the direction of the target damping force is different from the expansion / contraction direction of the shock absorber, the output lower limit line takes a constant value with respect to the change in the target damping force corresponding to the same direction as the direction. Correspondingly, the output upper limit line that takes a constant value with respect to the change of the target damping force, the output lower limit line, and the output upper limit line are connected, and the direction of the target damping force is different from the expansion and contraction direction of the shock absorber, and the shock absorber can output Output possible line that changes according to the target damping force, and the output possible line is a relaxation line whose inclination is smaller than the output possible line with respect to one or both of the output lower limit line and the output upper limit line. Suspension device characterized by being connected via The suspension device according to claim 1, wherein the relaxation line is connected to the output lower limit line or the output upper limit line with a gradually decreasing inclination. The control device adjusts the expansion / contraction speed of the buffer with respect to the target current command value or target voltage command value obtained by the relaxation line connected to the output lower limit line and the output upper limit line that minimizes the damping force of the buffer. The suspension apparatus according to claim 1 or 2, wherein a final target current command value or target voltage command value is obtained by multiplying a gain determined accordingly.

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