JP2014172594A - Damper speed detection device - Google Patents

Abstract

A speed detection device capable of accurately detecting a stroke speed of a damper is provided.
In order to achieve the above object, a speed detection apparatus according to the problem solving means of the present invention comprises a displacement sensor 2 for detecting a relative displacement X between a sprung member B and an unsprung member W of a vehicle, and the sprung. The stroke speed Vd of the damper D is obtained based on the damping coefficient of the damper D interposed between the member B and the unsprung member W and the relative displacement X.
[Selection] Figure 1

Description

  The present invention relates to a damper speed detection device.

  In the damper control device that controls the damping force of the damper interposed between the sprung member and the unsprung member of the vehicle, for example, paying attention to the stroke speed of the damper and the vertical speed of the sprung member, There are some that try to realize a skyhook damper based on the Karnop switching law, and when the stroke speed of the damper and the speed of the sprung member are in the same direction, the speed of the sprung member is multiplied by the skyhook gain. When the damper damping force is output to the damper and the stroke speed of the damper is different from the speed of the sprung member, the damping force of the damper is set to 0 (see Patent Document 1).

JP 2011-213198 A

  Such a damper control device can suppress the vibration of the sprung member and improve the riding comfort in the vehicle by performing the above-described control. In order to exert the damping force according to the target damping force, the stroke speed of the damper must be detected.

  In general, in order to detect the stroke speed of the damper, as in the conventional damper control device described above, the relative displacement between the suspension arm of the vehicle and the vehicle body, the rotation angle of the arm with respect to the vehicle body, and the like are detected by a sensor. It is obtained by differentiating the signal detected in (1). What is detected by the sensor is equivalent to the displacement, so that the displacement is differentiated to obtain the stroke speed of the damper.

  However, anti-vibration rubber called mount rubber or bush is interposed between the damper and the vehicle body, and between the damper and the arm, and this anti-vibration rubber also vibrates. If the coefficient needs to be variable and the damping coefficient of the damper is changed, the stroke share between the anti-vibration rubber and the damper changes, so the stroke speed obtained as described above and the actual stroke speed of the damper In this case, there is inevitably a deviation, and the stroke speed of the damper cannot be detected accurately.

  In particular, when controlling the damper according to the above-described Karnop switching law, it is important to detect the change in the stroke direction of the damper. However, as described above, the stroke speed of the damper includes an error. This can lead to a loss of ride comfort in the vehicle.

  Accordingly, the present invention has been developed to improve the above-described problems, and an object of the present invention is to provide a damper speed detection device that can accurately detect the stroke speed of the damper. .

  In order to achieve the above object, the problem solving means of the present invention includes a displacement sensor for detecting a relative displacement between a sprung member and an unsprung member of a vehicle, and the sprung member and the unsprung member from the relative displacement. A damper speed detection device including a speed calculation unit for obtaining a stroke speed of a damper interposed therebetween, wherein the speed calculation unit obtains the stroke speed based on the relative displacement and a damping coefficient of the damper. Features.

  In the damper speed detecting device of the present invention, the stroke speed is obtained in accordance with the change in the damping coefficient of the damper.

  Therefore, the damper speed detecting device of the present invention can detect the stroke speed of the damper with high accuracy.

It is a lineblock diagram of a damper control device to which a damper speed detecting device in one embodiment was applied. It is a schematic longitudinal cross-sectional view of a damper. It is a figure explaining an example of the relationship between the damping characteristic of a damper, and the electric current amount given to the damping force adjustment part of a damper. It is the figure which showed the frequency transfer characteristic of the stroke speed calculation type | formula. It is a figure which shows an example of a structure of a speed calculating part. It is a figure explaining the other example of the relationship between the damping characteristic of a damper, and the electric current amount given to the damping force adjustment part of a damper. It is a lineblock diagram of the damper speed detector in one modification of one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, the damper speed detection device 1 includes a displacement sensor 2 that detects a relative displacement X between a sprung member B and an unsprung member W of the vehicle, and a sprung member from the relative displacement X detected by the displacement sensor 2. A speed calculation unit 3 for obtaining a stroke speed Vd of a damper D interposed between B and the unsprung member W is provided.

  The damper speed detection device 1 is applied to a damper control device E that controls the damping force of the damper D, and the detected stroke speed Vd is input to the damper control device E.

  The damper D incorporates a damping force adjustment unit 4 that adjusts the damping force according to a control signal from the damper control device E. The damper control device E gives a control command to the damping force adjustment unit 4 to provide a damper D. The damping force is adjusted.

  Hereinafter, each part will be described. As shown in FIG. 1, in this example, a mount rubber M arranged in series with a damper D is interposed between an unsprung member B and an unsprung member W in the vehicle. The suspension spring S is interposed between the sprung member B and the unsprung member W. Therefore, the sprung member B is elastically supported by the suspension spring S. The unsprung member W includes a suspension arm A and a wheel T that are swingably attached to a sprung member B that is a vehicle body.

  The damper D is interposed between the sprung member B and the suspension arm A together with the mount rubber M. When the sprung member B and the unsprung member W vibrate relatively in the vertical direction, the damper D moves up and down together with the mount rubber M. It is designed to vibrate in the direction.

  The damper D is, for example, as shown in FIG. 2, a cylinder 12, a piston 13 slidably inserted into the cylinder 12, and a slidably inserted into the cylinder 12 and coupled to the piston 13. The piston rod 14, the two pressure chambers 15, 16 partitioned by the piston in the cylinder 12, the passage 17 that connects the pressure chambers 15, 16, and the damping force adjustment that gives resistance to the flow of fluid passing through the passage 17 The fluid pressure damper includes the portion 4. And this damper D exhibits the damping force which gives resistance in the damping force adjustment part 4 and suppresses the said expansion / contraction operation | movement, when the fluid with which the pressure chamber filled according to the expansion / contraction operation | movement passes a channel | path, and a spring The relative movement of the upper member and the unsprung member is suppressed.

  In addition to hydraulic oil, water, aqueous solution, or gas can be used as the fluid. When the fluid is a liquid and the damper D is a single rod type damper, the damper D includes a gas chamber and a reservoir to compensate for the volume of the piston rod 14 entering and exiting the cylinder 12. In some cases, the gas chamber and the reservoir may not be provided.

  In addition, when the damper D is provided with a reservoir and is set to a uniflow type in which fluid is discharged through a passage leading from the cylinder 12 to the reservoir even when the damper D is extended or contracted, a middle of a passage leading from the cylinder 12 to the reservoir Alternatively, the damping force adjusting unit 4 may be provided so as to exert a damping force by giving resistance to the fluid flow.

  The damping force adjusting unit 4 includes, for example, a damping valve that makes the flow passage area of a passage (not shown) of the damper D variable, a solenoid that can adjust the flow passage area of the passage 17 by driving the valve body, A damping force generated by the damper D by changing the resistance applied to the fluid flowing through the passage 17 by adjusting the amount of current applied to the solenoid or the actuator and adjusting the flow passage area of the passage. Can be adjusted. In this case, for example, if the amount of current applied to the damping force adjusting unit 4 is increased if the stroke speed of the damper D is not changed, the damping force of the damper D is also increased. As shown in FIG. Is a damping coefficient of the damper D depending on the amount of current between a soft damping characteristic when the amount of current supplied to the damping force adjusting unit 4 is minimized and a hard damping characteristic when the amount of current is maximized. Can be made variable.

  The above-described configuration of the damping force adjusting unit 4 is an example. For example, when the damper D fills the pressure chambers 15 and 16 with an electroviscous fluid or a magnetorheological fluid, a damping valve is provided in the passage 17. Instead of this, a device capable of applying an electric field or a magnetic field is incorporated, and this is used as the damping force adjusting unit 4, and the magnitude of the electric field or the magnetic field is adjusted by the voltage or current supplied from the damper control device E to The generated damping force of the damper D may be varied by changing the resistance applied to the flowing fluid. In addition, when the damper D uses an electrorheological fluid, the damping coefficient is adjusted according to the magnitude of the electric field applied to the passage 17. Therefore, the damper D is controlled by increasing or decreasing the voltage applied to the damping force adjusting unit 4. The control device E may obtain a voltage value as the control command value and apply a voltage according to the voltage value to be supplied to the damping force adjusting unit 4.

  Furthermore, in addition to the above, the damper D may be an electromagnetic damper that exhibits a damping force that suppresses the relative movement of the sprung member and the unsprung member by electromagnetic force. As the electromagnetic damper, for example, a motor, It is comprised including the motion conversion mechanism which converts the rotational motion of a motor into linear motion, or it is set as a linear motor. As described above, when the damper D is an electromagnetic damper, the damping force adjusting unit 4 may be a motor driving device that adjusts the current flowing through the motor or the linear motor.

  The damper control device E includes, for example, a damping force adjustment unit based on the speed sensor 5 that detects the vertical speed of the sprung member B, and the vertical speed of the sprung member B and the stroke speed Vd that is detected by the damper speed detection device 1. 4 and a command calculation unit 6 for obtaining a control command to be supplied to the control unit 4 to control the damping force of the damper D.

  For example, when performing skyhook control, the command calculation unit 6 multiplies the vertical speed by the skyhook gain and the target damping force when the vertical speed of the sprung member B and the direction of the stroke speed Vd coincide. On the other hand, if the direction of the vertical speed of the sprung member B and the direction of the stroke speed Vd are different, the target damping force is set to 0, and a control command is generated so that the damper D exhibits the damping force according to the target damping force. The control command is output to the damping force adjustment unit 4. The damping force adjustment unit 4 changes the damping coefficient according to the amount of current supplied as described above. Therefore, as shown in FIG. 3, the damping characteristic of the damper D becomes a hard characteristic with a large damping coefficient when the amount of current applied to the damping force adjusting unit 4 is increased, and is attenuated when the amount of current applied to the damping force adjusting unit 4 is decreased. This is a software characteristic with a small coefficient. That is, the damping characteristic of the damper D can be adjusted according to the amount of current. For this reason, the command calculation unit 6 supplies the damping force adjusting unit 4 with the damping force according to the target damping force from the stroke speed Vd of the damper D detected by the damper speed detecting device 1 and the target damping force. The amount of current to be obtained is obtained.

  For example, the displacement sensor 2 detects the rotational angle of the sprung member B of the suspension arm A, and detects the relative displacement X in the vertical direction of the sprung member B and the unsprung member W from this rotational angle. However, a stroke sensor that directly detects the relative displacement X in the vertical direction between the suspension arm A and the sprung member B may be used.

  The speed calculation unit 3 obtains the stroke speed Vd based on the relative displacement X and the damping coefficient of the damper D input from the damper control device E. A resonance frequency of a vibration system (hereinafter referred to as “mount rubber vibration system”) composed of a mount rubber M that is generally an elastic body and the masses of the piston 13 and the piston rod 14 of the damper D connected to the mount rubber M The band is about 100 Hz to 400 Hz, and the mount rubber M exhibits higher rigidity than the damper D. However, as the damping coefficient of the damper D increases, the rigidity of the damper D increases and the mount rubber M is relatively easily expanded and contracted. Become. That is, when the damping coefficient of the damper D is small, the damper D easily expands and contracts with respect to the mount rubber M, and the actual stroke speed of the pseudo damper D obtained by differentiating the relative displacement X detected by the displacement sensor 2 However, if the damping coefficient of the damper D is large, the damper D is less likely to expand and contract with respect to the mount rubber M, and is a pseudo value obtained by differentiating the relative displacement X detected by the displacement sensor 2. There is a difference between the stroke speed of the damper D and the actual stroke speed. Therefore, the speed calculator 3 calculates the stroke speed Vd from the relative displacement X when the damper D has a small damping coefficient, and the relative displacement X when the damper D has a large damping coefficient. From which the stroke speed Vd can be determined with high accuracy, and the damping coefficient of the damper D can be monitored to determine the stroke speed Vd according to the damping coefficient. .

  Specifically, the speed calculation unit 3 includes a soft stroke speed calculation formula corresponding to the minimum damping coefficient in the soft damping characteristic when the amount of current supplied to the damping force adjustment unit 4 is minimum, and the damping force. Two stroke speed calculation formulas for hardware corresponding to the maximum damping coefficient in the hard damping characteristics when the amount of current supplied to the adjusting unit 4 is maximum are held. In other words, the software stroke speed calculation formula is optimized for obtaining the stroke speed Vd when the damping coefficient is minimum, and the hardware stroke speed calculation formula is used when the damping coefficient is maximum. This is an arithmetic expression optimized for obtaining the stroke speed Vd.

This stroke speed calculation formula is expressed by the frequency transfer function G (s), and the stroke speed Vd (s) can be obtained by executing the calculation with the relative displacement X (s) as input. It can be done. In short, the relationship is Vd (s) / X (s) = G (s). In other words, the above-described calculation using the stroke speed calculation formula performs a process of filtering the signal of the relative displacement X (s) detected by the displacement sensor 2 using a filter set by the stroke speed calculation formula G (s). It will be. The filter characteristics set by the stroke speed calculation formula G (s) can be set, for example, as a characteristic a for software and a characteristic b for hardware as shown in FIG. The characteristics can be obtained by combining low-pass filters. The characteristic a for soft and the characteristic b for hardware have different break frequency, and the case where the break frequency of the hardware characteristic b corresponding to the case where the attenuation coefficient is large corresponds to the case where the attenuation coefficient is small. The characteristic becomes lower than the break frequency of the characteristic a for software. Here, the corner frequency of the characteristic b for hardware is made lower than the corner frequency of the characteristic a for software because the damper D is relatively relative to the mount rubber M as the damping coefficient increases. Since the stroke becomes difficult, the response of the displacement of the damper D is delayed with respect to the actual displacement of the suspension, and the phase of the stroke speed Vd of the damper D is also delayed with respect to the relative displacement X. The phase can be delayed by processing the relative displacement X detected by the displacement sensor 2 with the filter of the hardware characteristic b, and the stroke speed Vd of the damper D can be obtained accurately. Because you can. The stroke speed calculation expression G (s) for realizing such characteristics is, for example, (ω ² · s) / (s + ω) ^{2 where} s is the Laplace operator and ω is the angular frequency, and the stroke speed for software is The value of ω in the calculation formula may be set higher than the value of ω in the hardware stroke speed calculation formula.

  As described above, the stroke speed calculation formula includes the software for the case where the damping coefficient of the damper D is the minimum and the hardware for the case where the damping coefficient is the maximum, and the damping coefficient input to the speed calculation unit 3 is the minimum. In some cases, the stroke speed Vd may be obtained by using a software stroke speed calculation formula. When the damping coefficient input to the speed calculation unit 3 is maximum, the hardware stroke speed calculation formula is used. However, there is a case where the attenuation coefficient is neither minimum nor maximum. Therefore, as shown in FIG. 5, the speed calculation unit 3 includes a software stroke speed calculation unit 31 that obtains the provisional stroke speed Vdp1 from the relative displacement X using a software stroke speed calculation formula, and a hardware stroke speed calculation formula. And a hardware stroke speed calculation unit 32 that calculates the provisional stroke speed Vdp2 from the relative displacement X, and calculates the two provisional stroke speeds Vdp1 and Vdp2 by performing calculations using both of the two stroke speed calculation formulas. Furthermore, the linear interpolation part 33 which calculates | requires stroke speed Vd by linear interpolation according to an attenuation coefficient is provided. Specifically, for example, when the minimum attenuation coefficient is 1, the maximum attenuation coefficient is 5, and the attenuation coefficient of the current damper D input from the damper control device E is 2, the attenuation coefficient is 1 , The calculation result by the stroke speed calculation formula corresponding to the case, that is, the provisional stroke speed Vdp1 is 0.1 m / s and the damping coefficient is 5, the calculation result by the stroke speed calculation formula corresponding to If the stroke speed Vdp2 is 0.2 m / s, the stroke speed Vd is 0.1 × 3/4 + 0.2 × 1/4 = 0.125 m / s by linear interpolation. Therefore, in this case, the stroke speed Vd is obtained as 0.125 m / s and is input to the damper control device E. In this case, since the damping coefficient has a relationship determined by the amount of current supplied to the damping force adjustment unit 4 as described above, the amount of current supplied to the damping force adjustment unit 4 is supplied to the linear interpolation unit 33. May be input directly, or the value of the attenuation coefficient converted from the amount of current may be input.

  As described above, in the damper speed detection device 1 of the present invention, the stroke speed Vd of the damper D is accurately obtained by using the stroke speed calculation formula suitable for the damping coefficient corresponding to the change of the damping coefficient of the damper D. It can be detected well.

  In addition, since the stroke speed Vd can be accurately detected by the damper speed detection device 1, the damping force control of the damper D by the damper control device E can be improved, and in particular, the damper can be controlled by the Karnop switching law. , The detection of switching of the stroke direction of the damper D becomes accurate, so that the ride comfort in the vehicle can be improved.

  Two or more stroke speed calculation formulas G (s) may be prepared instead of the above-described two. For example, the stroke speed Vd when the damping coefficient is an intermediate value between the minimum and maximum values. When the stroke speed calculation formula optimized to obtain the value is prepared and the damping coefficient is between the minimum and intermediate values, the stroke speed calculation formula for software and the stroke speed calculation formula optimized for the intermediate value are The provisional stroke speeds Vdp1 and Vdp2 may be obtained by using them, and the stroke speed Vd may be obtained by linear interpolation. Thus, a large number of stroke speed arithmetic expressions optimized for an arbitrary attenuation coefficient are prepared, Two stroke speed calculation formulas corresponding to the most recent damping coefficient on both sides of the damping coefficient of the damper D are selected, and the relative variable is calculated using each selected stroke speed calculation formula. Seeking two interim stroke speed VDP1, VDP2 from X, it may determine the stroke speed Vd by the linear interpolation from these provisional stroke speed VDP1, VDP2.

  The stroke speed calculation formula is an example, and a calculation formula optimized in accordance with the attenuation coefficient may be used, and is not limited to the above calculation formula.

In the damper D described above, since the damping coefficient can be changed according to the amount of current supplied to the damping force adjusting unit 4, the stroke speed calculation formula G (s) is expressed as (ω ² · s). / (S + ω) ² , the attenuation coefficient is C, for example, ω = β−C · α, and the value of ω when C takes the minimum value is the value of the break frequency in the software characteristic a. If the value of ω when C takes the maximum value is set to the value of the breakpoint frequency in the hardware characteristic b, the stroke speed calculation formula G (s) is set according to the damping coefficient. Ω can be changed, and the stroke speed Vd can always be obtained by the optimum stroke speed calculation formula G (s) according to the attenuation coefficient without using linear interpolation as described above.

  On the other hand, when the damping characteristic of the damper D is, for example, as shown in FIG. 6, when the stroke speed Vd is in the low speed range, the damping force changes approximately proportionally to the stroke speed Vd and is attenuated when reaching the high speed range. When the damping characteristic of the damper D can be changed within the variable width by the amount of current applied to the damping force adjustment unit 4, the coefficient is reduced. When the damping coefficient of the damper D cannot be uniquely determined from the amount of current, the damping coefficient can be conveniently calculated by the following procedure.

  When the pseudo stroke speed obtained by differentiating the relative displacement X detected by the displacement sensor 2 is in the low speed region, the damping force changes approximately proportionally to the stroke speed Vd as described above. For example, it can be considered that the damping coefficient can be changed by the amount of current applied to the damping force adjusting unit 4.

  Therefore, when the pseudo stroke speed is in the low speed range, the above procedure, that is, hold two or more stroke speed calculation expressions optimized for an arbitrary damping coefficient, or depending on the damping coefficient. If the breakpoint frequency of the stroke speed calculation formula is changed, the stroke speed Vd can be obtained in the same manner as described above.

  In addition, when the pseudo stroke speed is in the high speed range, the damping coefficient is smaller than that in the low speed range even if the amount of current is large. Therefore, in this range, the stroke optimized for a small damping coefficient is used. If the stroke speed Vd is obtained using the speed calculation formula, the stroke speed Vd of the damper D having the damping characteristic shown in FIG. 6 can also be obtained precisely.

  Specifically, as shown in FIG. 7, the speed calculator 3 differentiates the relative displacement X detected by the displacement sensor 2 to obtain a pseudo stroke speed, and the pseudo stroke speed and attenuation. It is only necessary to provide an attenuation coefficient correction unit 35 that receives an input of the amount of current supplied to the force adjustment unit 4 and corrects the attenuation coefficient of the damper D. The stroke speed calculation formula has, for example, the maximum attenuation coefficient. Suppose you have one optimized for the case and one optimized for the minimum.

  The attenuation coefficient correction unit 35 compares the pseudo stroke speed with a threshold value that defines the low speed range and determines that the pseudo stroke speed is in the low speed range, obtains the attenuation coefficient from the current amount, When it is determined that the stroke speed is in the high speed range, for example, the attenuation coefficient is minimized regardless of the amount of current. Separately, the speed calculation unit 3 obtains the temporary stroke speed Vdp1 from the relative displacement X using the software stroke speed calculation formula, and obtains the temporary stroke speed Vdp2 from the relative displacement X using the hardware stroke speed calculation formula. . Then, the attenuation coefficient corrected by the attenuation coefficient correction unit 35 as described above is input to the linear interpolation unit 33, and the stroke speed Vd is obtained from the temporary stroke speeds Vdp1 and Vdp2 by linear interpolation according to the corrected attenuation coefficient. In this way, specifically, the stroke speed Vd of the damper D having the damping characteristic shown in FIG. 6 can be determined precisely. In this case, since the damping coefficient is determined by the amount of current applied to the damping force adjustment unit 4, the damping coefficient correction unit 35 does not obtain the damping coefficient but the amount of current actually flowing through the damping force adjustment unit 4. The amount of current corresponding to the attenuation coefficient may be obtained from, that is, the actual amount of current may be corrected, and the corrected amount of current may be input to the linear interpolation unit 33.

  In the case of this embodiment, the damper speed calculation unit 1 is not illustrated as a hardware resource, but specifically, for example, an A / D converter for capturing a signal output from the displacement sensor 2; A storage device such as a ROM (Read Only Memory) in which a program used for processing necessary for the calculation of the stroke speed Vd is stored, and 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 to the CPU, and the CPU executes the program to realize the operation of the speed calculation unit 3. .

  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 damper speed detection device of the present invention can be used for vibration control applications of vehicles.

DESCRIPTION OF SYMBOLS 1 Damper speed detection apparatus 2 Displacement sensor 3 Speed calculation part B Sprung member D Damper W Unsprung member

Claims (5)

A displacement sensor for detecting a relative displacement between an unsprung member and an unsprung member of the vehicle; and the damper based on a damping coefficient of the damper interposed between the unsprung member and the unsprung member and the relative displacement. A damper speed detection device comprising a speed calculation unit for determining the stroke speed of the damper. The speed calculation unit has at least two stroke speed calculation formulas corresponding to the magnitude of the attenuation coefficient, and obtains a stroke speed from the relative displacement using the stroke speed calculation formula. The damper speed detection device according to claim 1. The speed calculation unit has at least two stroke speed calculation formulas corresponding to the magnitude of the damping coefficient, selects at least one stroke speed calculation formula from the damping coefficient, and selects from the relative displacement The damper speed detecting device according to claim 2, wherein the stroke speed is obtained by using the stroke speed calculation formula. The speed calculation unit selects two stroke speed calculation formulas corresponding to the damping coefficients on both sides of the damping coefficient from the stroke speed calculation formulas, and uses the selected stroke speed calculation formulas to calculate the relative speeds. 4. The damper speed detecting device according to claim 2, wherein the two temporary stroke speeds are obtained from the displacement, and then the stroke speed is obtained by linear interpolation according to the damping coefficient of the damper. The speed calculation unit includes a stroke speed calculation expression expressed by a frequency transfer function, changes the angular frequency of the stroke speed calculation expression according to the attenuation coefficient, and obtains the stroke speed from the relative displacement. The damper speed detecting device according to any one of claims 1 to 4.

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