JP2015101261A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device capable of working as an active suspension which is reduced in energy consumption, constructed in a simple structure, and low in cost.SOLUTION: A suspension device S comprises: a cylinder 1; a piston 2 which is movably inserted into the cylinder 1; an expansion body D including a rod 3 which is movably inserted into the cylinder 1 and connected with the piston 2; an expansion side chamber R1 and a pressure side chamber R2 which are arranged in the expansion body D; a damping passage 4 and a pump passage 5 which communicate with the expansion side chamber R1 and the pressure side chamber R2 in parallel; a variable attenuation valve 6 which is arranged halfway in the damping passage 4 to provide resistance against flow of passing fluid; a bidirectional discharge type pump 7 which is arranged halfway in the pump passage 5; a motor 8 which drives the pump 7; and a controller C which controls the variable attenuation valve 6 on the basis of a target control force Fref, obtains a target rotational number Nref of the motor 8 to control the motor 8.

Description

  The present invention relates to a suspension device.

  As this type of suspension device, for example, there is one that functions as an active suspension interposed between a vehicle body and an axle of a vehicle. Specifically, a cylinder and a cylinder that is movably inserted into the cylinder are provided. A piston that defines a pressure chamber therein, a rod connected to the piston, a flow path that communicates with the pressure chamber, and a hydraulic pump that supplies pressure oil to the pressure chamber (for example, Patent Documents) 1).

  In addition, as a suspension device that functions as a semi-active suspension, for example, a cylinder, a piston that is movably inserted into the cylinder and defines an extension side chamber and a pressure side chamber in the cylinder, a rod connected to the piston, and an extension There is a configuration including a flow path that communicates a side chamber and a pressure side chamber, and a damping force variable valve provided in the middle of the flow path (see, for example, Patent Document 2).

JP-A-63-176710 Japanese Patent Laid-Open No. 5-155224

  In the suspension device functioning as the active suspension described above, there is a problem that the hydraulic pump is constantly driven, energy consumption is large, the system is complicated, the cost is high, and it is uneconomical.

  On the other hand, the suspension device functioning as the semi-active suspension described above does not include a hydraulic pump that consumes a large amount of energy, so the energy consumption is small, and the system is simple and low cost, but is active because it is a passive damper. Since the force, that is, the force in the same direction as the expansion / contraction direction cannot be positively exerted, there is a surface inferior to the active suspension in terms of the vehicle vibration suppression effect.

  Accordingly, the present invention was devised to improve the above-mentioned problems, and the object is to provide a suspension device that can function as an active suspension, consumes less energy, has a simple configuration, and is low in cost. It is.

  In order to solve the above-described object, the problem solving means in the present invention includes a cylinder, a piston movably inserted into the cylinder, and a rod movably inserted into the cylinder and coupled to the piston. An expansion / contraction body provided, an extension side chamber and a compression side chamber provided in the extension / contraction body, an attenuation passage and a pump passage communicating in parallel with the extension side chamber and the compression side chamber, and a passage provided in the middle of the attenuation passage A variable damping valve capable of changing a flow rate control force characteristic that is a characteristic of a control force with respect to the pump flow rate of the expansion body, and a bidirectional discharge type pump provided in the middle of the pump passage. A suspension device comprising: a motor for driving the pump; a variable damping valve; and a control device for controlling the motor. Based on the target control force and controls the variable damping valve, obtains a target rotational speed of the motor, it controls the motor based on the target rotational speed.

  According to the suspension device of the present invention, not only can it function as an active suspension, but it only has to be driven when the pump needs to be driven, so that energy consumption is low, and the configuration is simple and the cost is low. It will be cheap.

It is the figure which showed the suspension apparatus in one Embodiment. It is the figure which showed the state which interposed the suspension apparatus in one Embodiment between the sprung member and the unsprung member of a vehicle. It is the figure which showed the relationship between the generated force of the suspension apparatus and piston speed in one Embodiment. It is a relationship diagram of the control force of the suspension device and the discharge flow rate of the pump. It is the figure which showed the suspension apparatus in one modification of one Embodiment. It is the figure which showed the suspension apparatus in the other modification of one Embodiment. It is the figure which showed the suspension apparatus in other embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, a suspension device S according to an embodiment includes a cylinder 1, a piston 2 that is movably inserted into the cylinder 1, and a rod that is movably inserted into the cylinder 1 and connected to the piston 2. 3, the expansion side chamber R1 and the compression side chamber R2 provided in the expansion body D, the attenuation passage 4 and the pump passage 5 that communicate the expansion side chamber R1 and the compression side chamber R2 in parallel, and attenuation. A variable damping valve 6 which is provided in the middle of the passage 4 to provide resistance to the flow of fluid passing therethrough and which can change the damping characteristics of the expansion and contraction body D; and a bidirectional discharge type pump 7 which is provided in the middle of the pump passage 5 The motor 8 that drives the pump 7, the variable damping valve 6, and the control device C that controls the motor 8 are configured.

  Further, in this suspension device S, the expansion / contraction body D enters and leaves the cylinder 1 because the rod 3 is inserted only into the expansion side chamber R1 and is a so-called single rod type expansion / contraction body. In order to compensate for the volume of the rod 3, an accumulator A is connected to the compression side chamber R2. The accumulator A pressurizes the inside of the cylinder 1 with internal pressure.

  When the telescopic body D is applied to a vehicle, for example, as shown in FIG. 2, the cylinder 1 is connected to the unsprung member W of the vehicle, the rod 3 is connected to the sprung member B, and the suspension spring VS is connected. The cylinder 1 may be connected to the sprung member B and the rod 3 may be connected to the unsprung member W. However, the cylinder 1 may be interposed between the sprung member and the unsprung member. In addition, the stretchable body D in the suspension device S is set to a single rod type in the illustrated embodiment, but may be set to a double rod type. When the elastic body D is set to a double rod type, the accumulator A may not be provided.

  The extension side chamber R1 and the pressure side chamber R2 are filled with a fluid such as hydraulic oil as a fluid, and the accumulator A is also filled with a liquid and a gas. As the liquid filled in the extension side chamber R1, the pressure side chamber R2, and the accumulator A, for example, a liquid such as water or an aqueous solution can be used in addition to the working oil. In the present invention, the chamber compressed during the expansion stroke is referred to as an expansion side chamber R1, and the chamber compressed during the contraction stroke is referred to as a compression side chamber R2.

  In this case, the damping passage 4 is provided in the piston 2, and communicates the extension side chamber R1 and the pressure side chamber R2, and a variable damping valve 6 and a damping valve 9 are provided in parallel on the way. In addition to the damping passage 4, there is provided a pump passage 5 for communicating the expansion side chamber R1 and the pressure side chamber R2. The attenuation passage 4 and the pump passage 5 communicate with the expansion side chamber R1 and the pressure side chamber R2 in parallel. doing. Therefore, the variable damping valve 6 and the damping valve 9 are provided in parallel with the pump 7 provided in the pump passage 5.

  In this example, the variable damping valve 6 is a variable orifice that can open and close the flow path. Although not shown in detail, for example, a direct acting actuator such as a solenoid and the actuator is driven by the actuator to open and close the orifice. In addition to a valve body, it includes a rotary actuator such as a stepping motor and a cylindrical rotary valve that opens and closes an orifice. In this example, the variable damping valve 6 and the damping valve 9 are arranged in parallel, but it is also possible to provide only the variable damping valve 6 without providing the damping valve 9, and the variable damping valve 6 has a flow path. The area may be changed stepwise or may be changed steplessly.

  The damping valve 9 is a throttle that allows two-way passage in the same way as the variable damping valve 6, but the variable damping valve 6 and the damping valve 9 allow only the flow of fluid from the expansion side chamber R1 to the compression side chamber R2. And a one-way valve that gives resistance to the flow, and a one-way valve that gives resistance to the flow while allowing only the flow of fluid from the compression side chamber R2 toward the extension side chamber R1 in parallel therewith. May be. Although the damping passage 4 is provided in the piston 2, the installation location is not limited to this and can be provided outside the cylinder 1.

  In turn, the pump 7 is set to a bi-directional discharge type, for example, a piston pump, and the rotation shaft of the pump 7 is connected to the motor 8 and is driven by the motor 8. ing. The pump 7 is driven by a motor 8 and functions as a fluid motor by the flow of fluid passing through the pump passage 5. The motor 7 acts as a generator to regenerate energy. Also good. Various types of motors, for example, brushless motors, induction motors, synchronous motors, etc., can be adopted as the motor 8 regardless of whether they are direct current or alternating current.

  Here, when the pump 7 is stopped without supplying power to the motor 8, when the expansion / contraction body D is forcibly expanded / contracted by an external input, the expansion side chamber R 1 to the compression side chamber R 2 via the attenuation passage 4 Alternatively, since the damping valve 6 provides resistance to the flow of fluid moving from the compression side chamber R2 to the expansion side chamber R1, it is possible to exert a generating force that suppresses expansion and contraction of the expansion body D.

  The telescopic body D takes the piston speed which is the moving speed of the piston 2 in the axial direction with respect to the cylinder 1 on the horizontal axis, and when the flow path area in the variable damping valve 6 is maximized, the generated force is taken on the vertical axis in FIG. The generated force characteristic along the line a in the graph exhibits the same generated force characteristic as that of a passive damper, and the damping force of the expansion body D depends on the piston speed unless the flow area of the variable damping valve 6 is changed. It takes a fixed value. Further, when the flow path in the variable damping valve 6 is interrupted, the expansion / contraction body D has the speed generation force characteristic along the line b in the graph of FIG. 3 and exhibits the same speed generation force characteristic as the passive damper, Unless the flow path area of the variable damping valve 6 is changed, the damping force of the expansion / contraction body D takes a fixed value with respect to the piston speed. Therefore, by changing the flow path area in the variable damping valve 6, the generating force of the expansion / contraction body D can be adjusted in the range from the line a to the line b in FIG. For example, when the variable damping valve 6 is a valve that can perform only two-stage switching in which the flow path is blocked and the flow path area is maximized, the speed generating force of either the line a or the line b in FIG. A characteristic is selected and the generating force of the expansion-contraction body D is adjusted.

  On the other hand, when the pump 7 is driven by the motor 8, the expansion body D can send fluid from the expansion side chamber R 1 to the compression side chamber R 2 or from the compression side chamber R 2 to the expansion side chamber R 1. The flow rate passing through the valve 6 can be controlled.

  Here, the piston speed in the telescopic body D is Vp, the cross-sectional area of the piston 2 is Ap, the cross-sectional area of the rod 3 is Ar, the flow rate discharged by the pump 7 is Qp, and the variable damping valve 6 and the damping valve 9 Let C be the proportionality constant, which is the relationship between the pressure loss that occurs with respect to the flow rate through which the whole passes, and let F be the generated force of the stretchable body D. Further, the piston speed Vp takes a positive value when the piston 2 is in the direction in which the piston 2 moves upward in FIG. 1 with respect to the cylinder 1, and the flow rate Qp causes the pump 7 to discharge fluid toward the extension side chamber R1. It takes a positive value at the time (forward rotation). Then, the generated force F becomes F = (Ap−Ar) · C · {(Ap−Ar) · Vp + Qp}. That is, the generated force F of the suspension device S is determined by the proportionality constant C adjusted by changing the piston speed Vp, the discharge flow rate Qp of the pump 7, and the flow passage area of the variable damping valve 6.

  When the expansion / contraction body D is in the contraction stroke (Vp <0), if the pump 7 is rotated forward and Qp is made larger than − (Ap−Ar) · Vp, F takes a positive value, and the suspension device S 3 can exert a positive generated force F in the second quadrant region in the graph of FIG. 3, and when the expansion / contraction body D is in the expansion stroke (Vp> 0), the pump 7 is reversed, and Qp is − ( If it is smaller than Ap−Ar) · Vp, F takes a negative value, and the suspension device S can exert a negative generated force F in the fourth quadrant region in the graph of FIG. 3. By adjusting the flow rate Qp in this way, the generated force F of the stretchable body D can be changed.

  In other words, in this suspension device S, the expansion / contraction body D can generate a force in the same direction as the expansion / contraction direction that could not be generated by a passive damper, and the expansion / contraction body D can be actively expanded / contracted by itself. The generated force can be adjusted.

  Then, by adjusting the flow rate of the pump 7, the generated force F can be made variable by translating the lines a and b in the horizontal direction in the graph of FIG. 3, specifically, the variable damping valve 6. When the flow path is opened to the maximum, the broken line d indicating the characteristic when the discharge flow rate of the pump 7 is maximized to the negative side from the broken line c indicating the characteristic when the discharge flow rate of the pump 7 is maximized to the positive side. The characteristic of the generated force F can be arbitrarily changed within the range up to the above, and when the variable damping valve 6 blocks the flow path, one point indicating the characteristic when the discharge flow rate of the pump 7 is maximized to the positive side. The characteristic of the generated force F can be arbitrarily changed in the range from the chain line e to the one-dot chain line f indicating the characteristic when the discharge flow rate of the pump 7 is maximized to the negative side.

  For example, when it is desired to cause the suspension device S to exert the generated force F in FIG. 3, the discharge flow rate Qp and the proportionality constant C of the pump 7 are determined so that the generated force F becomes the generated force F at the piston speed Vp at that time. May be discharged from the pump 7 to the extension side chamber R1 or the pressure side chamber R2.

  Thus, in the suspension device S of the present invention, not only can the telescopic body D be actively expanded and contracted to function as an actuator to function as an active suspension, but also function as a passive damper.

  Assuming that the differential pressure, which is the difference between the pressure in the extension side chamber R1 and the pressure in the compression side chamber R2, is ΔP, the generated force F generated by the expansion body D and the differential pressure ΔP have a relationship of F = ΔP · (Ap−Ar). Yes, it can be expressed as ΔP = C · {(Ap−Ar) · Vp + Qp}. That is, the differential pressure ΔP is determined by the piston speed Vp, the discharge flow rate Qp of the pump 7, and the proportional constant C. Further rewriting the above equation, ΔP = C · (Ap−Ar) · Vp + C · Qp. The first term on the right side of the above equation means the differential pressure ΔPp corresponding to the damping force Fp that is exhibited when the elastic body D functions as a passive damper, and the second term drives the pump 7. It means the differential pressure ΔPc corresponding to the control force Fc added to the damping force Fp. The sum of both is the differential pressure ΔP corresponding to the generated force F of the expansion body D.

  Since the control force Fc and the differential pressure ΔPc, the differential pressure ΔPc and the discharge flow rate Qp of the pump 7, and the discharge flow rate Qp of the pump 7 and the rotation speed of the motor 8 are proportional to each other, they are proportional to the target control force Fc. By controlling the rotation speed of the motor 8, the control force Fc of the expansion / contraction body D can be controlled.

  Therefore, the control device C basically obtains the target rotational speed Nref from the target control force Fref desired to be generated in the expansion / contraction body D, and controls the motor 8 based on the target rotational speed Nref.

  Incidentally, the motor 8 has a limit on the number of rotations that can be used, and the flow rate that can be discharged by the pump 7 is also limited. As shown in FIG. 4, when the absolute value of the target control force Fref exceeds a predetermined value Fc1, that is, when the variable damping valve 6 indicated by the middle line g in FIG. With the flow rate control force characteristic of the control force Fc with respect to the flow rate Qp, the desired target control force Fref cannot be generated if the variable damping valve 6 has the maximum flow path area. On the other hand, in the flow rate control force characteristic h of the control force Fc with respect to the discharge flow rate Qp of the pump 7 when the variable damping valve 6 indicated by the line h in FIG. 4 blocks the flow path, the absolute value of the target control force Fref is obtained. Even if the value exceeds the predetermined value Fc1, the desired target control force Fref can be generated if the variable damping valve 6 blocks the flow path. In this case, since the damping valve 9 is provided, the flow rate control force characteristic indicated by the line h depends on the characteristic of the damping valve 9 alone.

  Therefore, the variable damping valve 6 is controlled according to the magnitude of the target control force Fref to change the flow path area, and the control force Fc is applied to the expansion / contraction body D according to the target control force Fref within the range of the flow rate that the pump 7 can discharge. It will suffice to generate.

  Based on the above, the control device C, specifically, as shown in FIGS. 1 and 2, the target rotational speed calculation unit 10 for obtaining the target rotational speed Nref from the target control force Fref desired to be generated in the telescopic body D; And a motor control unit 11 that controls the motor 8 based on the target rotational speed Nref.

  More specifically, the control device C detects vibration information such as vertical acceleration and vertical speed of the sprung member B and unsprung member W of the vehicle, and expansion / contraction information such as piston speed and displacement of the expansion / contraction body D. Means 12, a target control force calculator 13 for obtaining a target control force Fref that is a control force to be generated on the expansion body D from various information detected by the sensor means 12, and a target control force obtained by the target control force calculator 13 A determination unit 14 that determines whether the absolute value of the target control force Fref is equal to or less than a predetermined value Fc1 from Fref, a valve control unit 15 that controls the variable damping valve 6 based on a determination result of the determination unit 14, and the above As a result of the determination by the determination unit 14, when the absolute value of the target control force Fref is less than the predetermined value Fc1, the first target rotation number calculation unit 16 that obtains the target rotation number Nref from the target control force Fref; As a result of the determination by the determination unit 14, when the absolute value of the target control force Fref is equal to or greater than the predetermined value Fc1, a second target rotation number calculation unit 17 that obtains the target rotation number Nref from the target control force Fref, and a first target rotation Based on the deviation εN, the rotational deviation computing unit 18 for obtaining the rotational deviation εN between the target rotational speed Nref obtained by the number computing unit 16 or the second target rotational speed computing unit 17 and the actual rotational speed N inputted from the motor 8. A compensator 19 that performs proportional-integral-derivative compensation to obtain a target command Iref and a driver 20 that receives the target current Iref and supplies the current I to the motor 8 in accordance with the target current Iref to drive the motor 8 are configured. ing.

  Therefore, in the suspension device S of this embodiment, the target rotational speed calculation unit 10 constituting the control device C includes the target control force calculation unit 13, the determination unit 14, the first target rotational speed calculation unit 16, and the first The other motor control unit 11 includes a rotation deviation calculation unit 18, a compensator 19 and a driver 20.

  The sensor means 12 detects information necessary for controlling the motor 8. For example, if the suspension device S is subjected to skyhook control, the vertical speed of the sprung member B may be detected. What is necessary is just to detect information required for the control to employ | adopt. As the sensor means 12, a sensor suitable for detecting information necessary for control may be used.

  The target control force calculation unit 13 obtains a target control force Fref, which is a control force that should be generated by the expansion / contraction body D, from various information detected by the sensor means 12. For example, when performing skyhook control, the sensor means The target control force Fref is obtained by multiplying the vertical speed of the sprung member B detected at 12 by the skyhook gain. Specifically, the target control force calculation unit 13 may obtain the target control force Fref based on the control theory employed in the control.

  The determination unit 14 compares the absolute value of the target control force Fref obtained by the target control force calculation unit 13 with a predetermined value Fc1, and if the absolute value of the target control force Fref is less than or equal to the predetermined value Fc1, The target rotational speed Nref is calculated by the one target rotational speed calculator 16, and when the absolute value of the target control force Fref exceeds the predetermined value Fc1, the target rotational speed Nref is calculated by the second target rotational speed calculator 17. Further, the determination unit 14 outputs the determination result to the valve control unit 15. The predetermined value Fc1 is set to the maximum value of the control force that can be generated by the expansion body D in consideration of the discharge flow rate limit of the pump 7 when the flow passage area of the variable damping valve 6 is maximized in advance.

  When the determination result of the determination unit 14 is that the absolute value of the target control force Fref is less than or equal to the predetermined value Fc1, the valve control unit 15 outputs a control command to the variable damping valve 6 so as to maximize the flow path area. On the contrary, when the determination result of the determination unit 14 is that the absolute value of the target control force Fref exceeds the predetermined value Fc1, a control command is output to the variable attenuation valve 6 to flow. The variable damping valve 6 is controlled so as to block the path. When the variable damping valve 6 uses a direct acting actuator to open and close the flow path, the valve control unit 15 only needs to output a current command for controlling the thrust or position of the actuator. In order to make the flow path area of the variable damping valve 6 a desired area, the signal pulses required by the stepping motor may be output.

  The first target rotational speed calculation unit 16 obtains the target rotational speed Nref when the determination result of the determination unit 14 is that the absolute value of the target control force Fref is less than the predetermined value Fc1. In obtaining the target rotational speed Nref, the first target rotational speed calculation unit 16 assumes that the variable damping valve 6 is in a state where the flow path area is maximized, and sets the rotational speed required for the motor 8 to the target rotational speed Nref. Asking. The second target rotational speed calculation unit 17 obtains the target rotational speed Nref when the determination result of the determination unit 14 indicates that the absolute value of the target control force Fref is greater than or equal to the predetermined value Fc1. When determining the target rotational speed Nref, the second target rotational speed calculation unit 17 determines the rotational speed required for the motor 8 as the target rotational speed Nref, assuming that the variable damping valve 6 is in a state of blocking the flow path. . The target rotational speed Nref obtained in this way is input to the rotational deviation calculator 18. When the absolute value of the target control force Fref is the predetermined value Fc1, whether the variable damping valve 6 maximizes the flow path area or the variable damping valve 6 blocks the flow path, the target control force Fref is equal to the target control force Fref. Since the generated force can be output to the telescopic body D, the target rotational speed Nref may be determined by selecting either the first target rotational speed calculation unit 16 or the second target rotational speed calculation unit 17. Selecting the two target rotational speed calculation unit 17 is advantageous in that the target rotational speed can be reached quickly because the rotational speed of the motor 8 can be lowered.

  As described above, in the suspension device S, the flow control force characteristic of the expansion / contraction body D is controlled by controlling the variable damping valve 6 when the expansion / contraction body D generates the target control force Fref from the magnitude of the target control force Fref. Is set so that the telescopic body D can generate the control force Fc in accordance with the target control force Fref. In this setting, the target of the motor 8 required for the telescopic body D to generate the target control force Fref is set. The rotational speed Nref is obtained. In other words, the flow rate control force characteristic is set by the control of the variable damping valve 6 so that the expansion body D can generate the target control force Fref, and the discharge required for generating the target control force Fref on the set flow rate control force characteristic line. A target rotational speed Nref of the motor 8 that realizes the flow rate Qp is obtained. Since the change in the flow rate control force characteristic is a change in the proportional constant C, the proportional constant C is uniquely determined from the set flow rate control force characteristic. Therefore, the target rotational speed Nref of the motor 8 is determined from the magnitude of the target control force Fref. Can be requested.

  As described above, the variable damping valve 6 changes the magnitude of the resistance given in cooperation with the damping valve 9 to the flow rate passing through the damping passage 4 by opening or closing the flow path. Although the control force characteristic is adjusted, the variable damping valve 6 can change the flow rate control force characteristic in three or more stages. In this case, when the variable damping valve 6 is controlled, a plurality of predetermined values serving as threshold values set for the target control force Fref in order to select one from a plurality of flow rate control force characteristics are provided. The target control force Fref is compared with a predetermined value, one flow control force characteristic is selected, and the variable damping valve 6 is controlled to realize the selected flow control force characteristic, and passes through the variable damping valve 6. Adjust the resistance to fluid flow. In addition, in accordance with the flow rate control force characteristic selected by the determination unit 14, not only the first and second but also a target rotation number calculation unit is provided for each stage, and a calculation unit for obtaining the target rotation number Nref is prepared. The target rotational speed Nref of the motor 8 that is necessary for generating the target control force Fref in the telescopic body D with the selected flow rate control force characteristics may be obtained. Furthermore, when the variable damping valve 6 can adjust the flow control force characteristic steplessly, the damping body can be variably attenuated according to the value of the target control force Fref so that the telescopic body D can generate the target control force Fref. The target flow speed Nref of the motor 8 required for the adjusted flow rate control force characteristic may be obtained by adjusting the flow rate control force characteristic of the expansion body D with the valve 6. Therefore, as described above, the variable damping valve 6 may be not only a variable orifice that can open and close the flow path area but also a valve that controls the valve opening pressure.

  The rotation deviation calculation unit 18 is input from the motor 8 from the target rotation number Nref calculated by either the first target rotation number calculation unit 16 or the second target rotation number calculation unit 17 based on the determination result of the determination unit 14. The actual rotational speed N is subtracted to obtain the rotational deviation εN. The compensator 19 obtains the target current Iref by performing proportional-integral-derivative compensation based on the deviation εN. The compensator 19 may be a PI compensator that performs proportional-integral compensation, a PD compensator, or the like. As described above, the rotation deviation calculation unit 18 and the compensator 19 form a rotation speed feedback loop so as to obtain the target current Iref to be supplied to the motor 8 from the target rotation speed Nref.

  The target current Iref obtained by the compensator 19 is input to the driver 20. The driver 20 energizes a winding (not shown) to drive the motor 8 by PWM. Specifically, for example, the driver 20 forms a current feedback loop with the motor 8, and according to the input target current Iref, the current I energized to a winding (not shown) of the motor 8 is in accordance with the target current Iref. The duty ratio is determined to be controlled and the winding of the motor M is energized. The configuration of the driver 20 can be appropriately changed so as to be suitable for the control of the motor 8.

  In this way, the control device C is configured, controls the variable damping valve 6 based on the target control force Fref of the expansion body D, obtains the target rotational speed Nref of the motor 8, and based on the target rotational speed Nref. Since the motor 8 is controlled, the range in which the control force Fc of the expansion body D can be output can be widened. Therefore, according to the suspension device S of the present invention, a wide range of control force can be generated in the telescopic body D, so that the riding comfort in the vehicle can be improved.

  Further, as shown in FIG. 4, when the absolute value of the target control force Fref is equal to or less than the predetermined value Fc1, the rate of increase of the control force Fc with respect to the rotational speed of the motor 8, that is, the discharge flow rate Qp of the pump 7 is reduced. Therefore, even if a rotational speed error of the motor 8 occurs, the error of the control force Fc corresponding to the error becomes small, so that the desired control force Fc can be easily generated.

  Further, a predetermined value Fc1 is set in advance, and the variable damping valve 6 is controlled by comparing the target control force Fref and the predetermined value Fc1, so that the target rotational speed Nref is obtained. The flow rate control force characteristic that is changed by the variable damping valve 6 for obtaining the target rotational speed Nref can be determined based on the comparison result with the absolute value of the target control force Fref, and the calculation of the target rotational speed Nref is facilitated and the map Use of arithmetic is also possible. This is because the variable damping valve 6 can change the flow control force characteristic in three or more stages, and a predetermined value required for selecting the flow control force characteristic is provided corresponding to the flow control force characteristic, and the target rotational speed is set. The same applies to the case where Nref is calculated according to the flow rate control force characteristics, and the above-mentioned merit can be enjoyed.

  In the above description, the sensor means 12 and the target control force calculation unit 13 for obtaining the target control force Fref, which is a control force to be generated on the telescopic body D, from various information detected by the sensor means 12 are provided. These may be integrated into a higher-order control device than the control device C, and the target control force Fref may be input to the control device C from the higher-order control device.

  Further, the control force to be generated in the stretchable body D is not limited to that obtained according to the Skyhook control law, and any control law for obtaining the control force can be adopted. Specifically, for example, it is possible to employ a control law that calculates the optimal control force for vehicle roll restraint control and control that suppresses pitching and squat during braking / driving. It is sufficient to obtain the control force using the above.

  Further, as hardware resources in each part of the control device C described above, specifically, for example, although not illustrated, an amplifier for amplifying a signal output from the sensor means 12, and an analog signal is converted into a digital signal. A well-known system comprising a converter, a storage system such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a crystal oscillator, and a computer system comprising a bus line connecting these. The control processing procedure for executing various calculations required in the process of processing each signal and obtaining the target current Iref from the target control force Fref is stored in advance in a ROM or other storage device as a program. And computer controlled Each section is constructed by executing the management procedure.

  In the suspension device S configured as described above, the pump 7 is not necessarily driven in the scene where the generated force is expected as a passive damper, and is driven only when the pump 7 needs to be driven. Therefore, energy consumption is small, and the configuration is simple, so the cost is low.

  Therefore, according to the suspension device S of the present invention, it can function as an active suspension, consumes less energy, and has a simple configuration and low cost.

  The accumulator A described above may be formed between the cylinder 1 and the outer cylinder 30 by providing an outer cylinder 30 on the outer periphery of the cylinder 1 as shown in FIG. In this case, the pump passage 5 may be communicated with the pressure side chamber R2 via the accumulator A.

  In order to compensate the volume of the rod 3 entering and exiting the cylinder 1, instead of installing the accumulator A, for example, a sliding partition wall FP is slidably inserted into the cylinder 1 as shown in FIG. Thus, an air chamber G may be formed in the cylinder 1, and the volume of the rod 3 entering and exiting the cylinder 1 due to a change in the volume of the air chamber G may be absorbed. In forming the air chamber G, although not shown, it may be formed of a bladder, a bellows, or the like.

  Furthermore, like the suspension device S2 of the other embodiment of FIG. 7, it is also possible to employ a stretchable body D2 different from the stretchable body D of the suspension device S1 of the one embodiment. The expansion / contraction body D <b> 2 has a rod 33 that is cylindrical and has a top closed, and an inner rod 34 that rises from the bottom of the cylinder 31 is slidably inserted into the rod 33.

  Further, an annular piston 32 is connected to the lower end of the rod 31 in FIG. 7, and the piston 32 is in sliding contact with the inner periphery of the cylinder 31. R3 is formed.

  Further, the inner rod 34 is inserted into the rod 33 so that a pressure side chamber R4 is formed by the inner rod 34. The expansion side chamber R3 and the pressure side chamber R4 are communicated with each other by the attenuation passage 35, and the expansion side chamber R3 and the pressure side chamber R4 are also communicated by the pump passage 36.

  A variable damping valve 37 and a damping valve 40 are provided in the middle of the damping passage 35, and a bidirectional discharge type pump 38 driven by a motor 39 is provided in the middle of the pump passage 36.

  Therefore, even in the suspension device S2, the control force Fc generated by the suspension device S2 can be adjusted by driving the pump 38 by the control device C, as in the suspension device S1, and the expansion body D2 can be positively moved. In addition to functioning as an active suspension by expanding and contracting, it can function as a passive damper. Even in the suspension device S2, the pump 38 is not necessarily driven in a scene where generation of the generated force is expected as a passive damper, and it is only necessary to drive the pump 38 when it is necessary. The consumption is small and the configuration is simple, so the cost is low.

In the suspension device S2, the annular pressure receiving area X of the piston 32 that receives the pressure in the expansion side chamber R3 and the pressure receiving area Y of the rod 33 that receives the pressure in the pressure side chamber R4 can be made equal. The body D2 can function as a double rod type expansion and contraction, and the accumulator for volume compensation can be eliminated. In addition, since the expansion body D2 does not require an accumulator and it is easy to ensure the stroke length, the mounting length of the suspension device S2 can be shortened.
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.

1, 31 Cylinder 2, 32 Piston 3, 33 Rod 4, 35 Damping passage 5, 36 Pump passage 6, 37 Variable damping valve 7, 38 Pump 8, 39 Motor 10 Target rotational speed calculation section 11 Motor control section A Accumulator C control Apparatus D, D1, D2 Stretch body R1, R3 Extension side chamber R2, R4 Pressure side chamber S, S1, S2 Suspension device

Claims (4)

A telescopic body comprising a cylinder, a piston movably inserted into the cylinder, and a rod movably inserted into the cylinder and coupled to the piston;
An extension side chamber and a compression side chamber provided in the stretchable body,
A damping passage and a pump passage communicating in parallel between the extension side chamber and the pressure side chamber;
A variable damping valve that is provided in the middle of the damping passage and provides resistance to the flow of fluid passing therethrough and can change a flow rate control force characteristic that is a characteristic of a control force for the pump flow rate of the expansion and contraction body;
A bidirectional discharge pump provided in the middle of the pump passage;
A motor for driving the pump;
A suspension device comprising the variable damping valve and a control device for controlling the motor,
The control device controls the variable damping valve based on a target control force of the telescopic body, obtains a target rotational speed of the motor, and controls the motor based on the target rotational speed. Suspension control device. The control device controls the variable damping valve to set the flow control force characteristic so that the telescopic body can generate a target control force. In the set flow control force characteristic, the telescopic body The suspension apparatus according to claim 1, further comprising a target rotational speed calculation unit that obtains the target rotational speed capable of generating the target control force.   When the target control force of the telescopic body is less than a predetermined value, the target rotational speed is obtained based on the flow rate control force characteristic when the variable damping valve maximizes the flow path, and the target control force of the telescopic body is 3. The suspension device according to claim 1, wherein, when the value is equal to or greater than the predetermined value, the target rotational speed is obtained based on a flow rate control force characteristic when the variable damping valve minimizes the flow path. A damping valve is provided in the damping passage in parallel with the variable damping valve,
The control device
A first target rotational speed calculation unit for obtaining the target rotational speed based on a flow rate control force characteristic in a state where the variable damping valve is open;
A second target rotational speed calculation unit for obtaining the target rotational speed based on a flow rate control force characteristic in a state where the variable damping valve is closed,
When the target control force of the telescopic body is less than a predetermined value, the variable damping valve is opened, and the target rotational speed is obtained by the first target rotational speed calculation unit,
4. When the target control force of the telescopic body is equal to or greater than the predetermined value, the variable damping valve is closed, and the target rotational speed is obtained by the second target rotational speed calculation unit. The suspension device according to claim 1.

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