JP2015168337A - vehicle absorber system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle absorber system having high practicality.SOLUTION: A vehicle absorber system comprises: (I) a first attenuation force generator 106 for changing magnitude of attenuation force to be generated by changing valve opening pressure of a main valve by a solenoid valve; (II) and a second attenuation force generator 108 disposed in parallel to the first attenuation force generator 106, passing working fluid flowing following to telescopic motion of a cylinder 14, and generating attenuation force by applying resistance to the flow of the working fluid, and is mainly formed of the solenoid valve for changing magnitude of attenuation force by adjusting degree of valve opening of itself, according to supplied current. The first attenuation force generator 106 and second attenuation force generator 108 are controlled for controlling attenuation force with respect to telescopic motion of the cylinder 14.

Description

  The present invention relates to a vehicle absorber system for generating a changeable magnitude of a damping force with respect to a relative motion between an unsprung portion and an unsprung portion.

  In the following patent document, (A) a housing for storing hydraulic fluid, a piston slidably disposed in the housing, a rod having one end connected to the piston and the other end extending from the housing And (C) a hydraulic fluid flow that accompanies the expansion and contraction of the cylinder. The vehicle absorber system includes a damping force generator that generates a damping force with respect to the expansion and contraction of the cylinder, and generates a damping force having a magnitude corresponding to the supplied current. Is described. More specifically, the damping force generator includes (a) a main flow path through which hydraulic fluid flows as the cylinder expands and contracts, and (b) provided in the main flow path to provide resistance to the flow of hydraulic fluid. A main valve that generates a damping force, (c) a bypass path provided to bypass the main valve, and (d) a direction provided in the bypass path for closing the main valve. And (e) a solenoid valve that adjusts the valve opening pressure of the main valve by changing the internal pressure of the pilot chamber according to the supplied current. The damping force generated by changing the valve opening pressure of the main valve is changed.

JP 2011-007322 A

  The damping force generator using a solenoid valve controls the damping force against cylinder expansion / contraction from the low-speed region to the high-speed region, in other words, from the low flow rate region to the high flow rate region. However, the absorber described in the above-mentioned patent document is configured to generate a damping force against expansion and contraction of the cylinder in the medium speed range to the high speed range. That is, it is considered that the practicality of a vehicle absorber system including a damping force generator using a solenoid valve can be improved by making it possible to control the damping force against expansion and contraction of the cylinder in the very low speed region. This invention is made | formed in view of such a situation, and makes it a subject to provide the highly practical vehicle absorber system.

  In order to solve the above problems, the vehicle absorber system according to the present invention is configured to change the magnitude of the damping force generated by (I) changing the valve opening pressure of the main valve by the solenoid valve. 1 damping force generator, and (II) a damping force which is provided in parallel with the first damping force generator and allows the hydraulic fluid flowing along with the expansion and contraction of the cylinder to pass through and gives resistance to the flow of the hydraulic fluid. A second damping force generator composed mainly of a solenoid valve that changes the magnitude of the damping force to be generated by adjusting the degree of opening of the valve according to the supplied current. And controlling the first damping force generator and the second damping force generator to control the damping force against expansion and contraction of the cylinder.

  According to the vehicle absorber system of the present invention, it is possible to control the damping force against expansion and contraction of the cylinder in a wide speed range by using two damping force generators provided in parallel. By having such an advantage, the vehicle absorber system of the present invention is highly practical.

Aspects of the Invention

  In the following, some aspects of the invention that can be claimed in the present application (hereinafter sometimes referred to as “claimable invention”) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the claimable inventions, and is not intended to limit the combinations of the constituent elements constituting those inventions to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which some constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following items, item (1) corresponds to claim 1, and the technical features described in item (2) are added to item 1 and item 2 (3). (1) to which the technical features described in (4) and (5) are added to any one of claims 1 to 3. Is obtained by adding the technical features described in (6) and (7) to any one of claims 1 to 4 in claims 5 and (8). (6) is added with the technical features described in (6), and (7) is added with the technical features described in (9) in any one of claims 1 to 4. The technical feature described in (12) is added to claim 7 and the technical feature described in (13) is added to claim 8 in claim 8. There to claim 9, obtained by adding the technical features described in (14) to claim any one of claims 1 to 9 to claim 10, corresponding respectively.

(1) A vehicle having a housing for storing hydraulic fluid, a piston slidably disposed in the housing, a rod having one end connected to the piston and the other end extending from the housing. A cylinder which is arranged so as to be connected to the upper and lower parts of the spring and expands and contracts by relative movement between the upper and lower parts of the spring,
A first damping force generator and a second damping force generator, which are provided in parallel with each other, each of which gives resistance to the flow of hydraulic fluid accompanying expansion and contraction of the cylinder so as to change the damping force with respect to the expansion and contraction of the cylinder; Two damping force generators;
A vehicle absorber system comprising: a control device that controls the damping force against expansion and contraction of the cylinder by controlling the first damping force generator and the second damping force generator;
The first damping force generator is
(a) a main flow path through which hydraulic fluid flows when the cylinder expands and contracts; (b) a main valve provided in the main flow path that generates a damping force by applying resistance to the flow of hydraulic fluid; and (c) A bypass passage provided so as to bypass the main valve; (d) a pilot chamber provided in the bypass passage for applying an internal pressure in a direction to close the main valve; and (e) a supply. And a first solenoid valve that adjusts the valve opening pressure of the main valve by changing the internal pressure of the pilot chamber in accordance with the current that is applied, and the valve opening pressure of the main valve is changed by the first solenoid valve Configured to change the magnitude of the damping force generated by
The second damping force generator is
It is a valve that generates a damping force by allowing the hydraulic fluid flowing along with the expansion and contraction of the cylinder to pass therethrough and giving resistance to the flow of the hydraulic fluid, and adjusts the degree of opening of the valve according to the supplied current. A vehicle absorber system mainly composed of a second solenoid valve that changes the magnitude of the damping force generated by the above.

  The vehicle absorber system described in this section is a hydraulic shock absorber system, and is configured to control a damping force against expansion and contraction of a cylinder using two damping force generators. The “second damping force generator” described in this section is a so-called direct acting solenoid valve, and the “first damping force generator” is a pilot solenoid valve. The vehicle absorber system described in this section uses these two types of solenoid valves, so that the damping characteristics of the absorber are the damping characteristics of the first damping force generator and the damping characteristics of the second damping force generator. It is possible to add damping characteristics that can control damping force in a wide speed range.

  The “degree of valve opening” in the second solenoid valve described in this section is a term including the valve opening amount and ease of valve opening, and specifically, for example, formed by a valve seat and a valve body. It means the area of the flow path formed, the pressure at which the valve body separates from the valve seat, and the like.

Note that the damping force F generated by the shock absorber depends on the relative speed (hereinafter sometimes referred to as “stroke speed”) v _st between the spring top and the spring bottom. Can be expressed.
F = ζ · v _st ζ: damping coefficient Therefore, when comparing the damping force generated by the shock absorber, the same stroke speed v _st is assumed. In view of this, the magnitude of the damping force in this specification may mean a difference in damping force generation characteristics, specifically, the magnitude of the damping coefficient. It may mean a change in force generation characteristics, specifically a change in damping coefficient.

(2) The vehicle absorber system is
A first flow path provided in parallel with each other, each of which is a flow path through which hydraulic fluid flows in one direction as the cylinder expands and contracts, and the first damping force generator is provided; and A second flow path provided with the second damping force generator;
The vehicle absorber system according to (1), further comprising: a switching valve that switches between a state in which the flow of the hydraulic fluid to the first flow path is allowed and a state in which the flow is prohibited.

  In the aspect described in this section, the state where the first damping force generator is used and the state where it is not used can be switched by the switching valve. According to the aspect of this section, it is possible to generate the damping force only by the second damping force generator.

  (3) The switching valve is an on-off valve provided in the first flow path, and is a normally open valve, and the second solenoid valve is a normally closed valve. Vehicle absorber system.

  In the vehicle absorber system described in this section, when a failure occurs in which the system cannot be energized, the hydraulic fluid does not flow into the second flow path as the cylinder expands and contracts. The first damping force generator generates a damping force against expansion and contraction of the cylinder.

(4) The first damping force generator is
A fixed orifice that is provided in the bypass and provides resistance to a flow of hydraulic fluid accompanying at least one of expansion and contraction of the cylinder;
The first solenoid valve is
Provided downstream of the pilot chamber in the bypass passage, and controls the flow of hydraulic fluid from the pilot chamber to the downstream side of the bypass passage, thereby changing the internal pressure of the pilot chamber (1) Item 6. The vehicle absorber system according to any one of items (3) to (3).

  The mode described in this section is a mode in which the configuration of the first damping force generator is limited. In the first damping force generator described in this section, until the main valve is opened, the resistance of the hydraulic fluid relying on the fixed orifice becomes the main damping force against expansion and contraction of the cylinder. When the main valve opens, the resistance of the hydraulic fluid that relies on the main valve becomes the main damping force against the expansion and contraction of the cylinder. That is, in the first damping force generator described in this section, since the damping characteristic until the main valve opens depends on the fixed orifice, the damping force in the speed range until the valve opening pressure of the main valve is reached is I can't control it. Therefore, in the aspect described in this section, the damping force control in the low speed region by the second damping force generator is particularly effective.

(5) The vehicle absorber system is
The damping force generated by the first damping force generator depending on the fixed orifice is within the range of the damping force generated by the second damping force generator when the second solenoid valve is energized. The vehicle absorber system as set forth in (4).

  In the aspect described in this section, the relationship between the damping characteristic of the fixed orifice and the damping characteristic of the second damping force generator is limited. In the aspect described in this section, the range of the damping force generated by the first damping force generator and the range of the damping force generated by the second damping force generation are configured to partially overlap. According to the aspect of this section, it is possible to continuously connect the damping force even when switching between the first damping force generator and the second damping force generator.

(6) The control device
Based on the sprung speed which is the vertical speed of the upper part of the spring, the sprung speed based damping force control unit for controlling the supply current to the first solenoid valve and the second solenoid valve is configured (1 The vehicle absorber system according to any one of items) to (5).

  For example, the aspect described in this section can be an aspect capable of executing sprung vibration suppression control based on the skyhook control theory, so-called skyhook control. According to the aspect described in this section, it is possible to effectively suppress the vibration of the sprung portion.

(7) The control device
A target damping force determining unit that determines a target damping force that is a target of a damping force for expansion and contraction of the cylinder based on the sprung speed;
The sprung speed-dependent damping force control unit is
When the actual stroke speed, which is the actual speed at which the cylinder expands and contracts, is equal to or less than the stroke speed corresponding to the target damping force, which is the speed at which the cylinder extends and contracts, corresponding to the magnitude of the target damping force, A damping force is generated by the second damping force generator, and when the actual stroke speed is higher than the stroke speed corresponding to the target damping force, the damping force is controlled to be generated by the first damping force generator (6). The vehicle absorber system according to the item.

  The mode described in this section is a mode in which a switching condition between the first damping force generator and the second damping force generator is defined. According to the aspect of this aspect, the second damping force generator is used in the low speed range that is equal to or less than the target damping force-corresponding stroke speed, and the first damping force is greater than the target damping force-corresponding stroke speed. Using the generator, it is possible to control the damping force against expansion and contraction of the cylinder to an appropriate magnitude.

(8) The vehicle absorber system is
The range of the damping force generation characteristic of the first damping force generator when the first solenoid valve is energized and the damping force generation characteristic of the second damping force generator when the second solenoid valve is energized Is configured to partially overlap
The relationship between the target damping force-corresponding stroke speed and the damping force is set within a range in which the damping force generation characteristics of the first damping force generator and the damping force generation characteristics of the second damping force generator overlap (7 The absorber system for vehicles as described in the item).

  According to the aspect described in this section, it is possible to continuously connect the damping force when switching between the first damping force generator and the second damping force generator. Further, according to the aspect described in this section, even when an error occurs in the stroke speed obtained for use in the control, both of the two damping force generators are within a range in which the damping force can be generated. Since the switching is performed, it is possible to avoid a situation in which the damping force that is actually generated is suddenly changed without the damping force being generated.

(9) The control device
A hydraulic pressure difference-based damping force control unit is configured to control the supply current to the second solenoid valve based on the hydraulic pressure difference between the rod side chamber and the anti-rod side chamber partitioned by the piston in the housing. The vehicle absorber system according to any one of (1) to (5).

  The aspect described in this section can be an aspect in which the supply current is changed based on, for example, the magnitude of the hydraulic pressure difference between the two liquid chambers of the cylinder and the temporal change thereof. Based on the hydraulic pressure difference between the two liquid chambers, it is possible to estimate the expansion / contraction amount and expansion / contraction speed of the cylinder, and it is possible to generate an appropriate damping force against the expansion / contraction of the cylinder. Based on the above hydraulic pressure difference, it is possible to estimate the cylinder operation in the low speed range more accurately, and the mode of this section is particularly effective for controlling the damping force against the expansion and contraction of the cylinder in the low speed range. It is.

(10) The hydraulic pressure difference-based damping force control unit is
The vehicle absorber system according to (9), wherein a supply current to the second solenoid valve is controlled based on a temporal change in the hydraulic pressure difference.

(11) The hydraulic pressure difference-based damping force control unit
The vehicle absorber system according to item (10), wherein the current supplied to the second solenoid valve is controlled so that the damping force increases as the temporal change in the hydraulic pressure difference increases.

  The modes described in the above two terms are limited to the mode of controlling the supply current based on the temporal change of the hydraulic pressure difference. Since the amount of change over time of the hydraulic pressure difference increases earlier than the change in the magnitude of the hydraulic pressure difference, according to the modes of the above two terms, it also supports small expansion and contraction operations of the cylinder in the low speed range. Thus, it is possible to optimize the attenuation characteristics at an early stage.

(12) The control device further includes:
A sprung speed-based damping force control unit that controls a current supplied to the first solenoid valve and the second solenoid valve based on a sprung speed that is a vertical speed of the upper part of the spring;
When the actual stroke speed, which is the actual speed at which the cylinder expands and contracts, is less than or equal to the set stroke speed, the supply current to the second solenoid valve is controlled by the hydraulic pressure difference-based damping force control unit, and the actual stroke speed is In any one of the items (9) to (11), the supply current to the second solenoid valve is controlled by the sprung speed-dependent damping force control when the stroke speed is higher than the set stroke speed. The vehicle absorber system described.

  The aspect described in this section is configured such that both control based on the sprung speed and control based on the hydraulic pressure difference can be executed, and a method for properly using the two controls is embodied. When the control is performed based on the sprung speed, the vehicle is generally provided with a sprung acceleration sensor that acquires the vertical acceleration of the sprung portion. Then, the stroke speed may be estimated from the detection value of the sprung acceleration sensor and used for damping force control. However, in such a case, it is difficult to estimate a low stroke speed without error. In the aspect described in this section, since the control based on the hydraulic pressure difference is performed in the low speed range, it is possible to accurately estimate the expansion and contraction of the cylinder and generate a damping force having an appropriate magnitude.

(13) The set stroke speed is
In a state where hydraulic fluid does not flow to the second damping force generator and hydraulic fluid flows only to the first damping force generator, the first solenoid valve is supplied to the first solenoid valve so that the valve opening pressure of the main valve is minimized. The vehicle absorber system according to the item (12), which is set to a stroke speed when generating the minimum valve opening pressure when the supply current is controlled.

  The mode described in this section is a mode in which the set stroke speed, which is a threshold for switching between control based on the sprung speed and control based on the hydraulic pressure difference, is limited, and the main valve of the first damping force generator is Control based on the hydraulic pressure difference is executed in a low speed range where the valve is not opened.

(14) The vehicle absorber system is
Provided corresponding to each of the plurality of wheels, each of which is the cylinder, the plurality of first damping force generators and the plurality of cylinders that are the second damping force generators, the plurality of first damping force generators, and the plurality of wheels A second damping force generator;
The plurality of first damping force generators and the plurality of second damping force generators are configured as one unit, and each of the plurality of cylinders is connected to the unit by piping (1) to (1). 13. The vehicle absorber system according to any one of items 13).

  The vehicle absorber system described in this section suppresses an increase in the size of the absorber arranged for each wheel, and the plurality of first damping force generators and the plurality of second damping force generators are unitized. In this way, it is excellent in terms of mountability on the vehicle.

It is the schematic which shows the absorber system for vehicles which is an Example of claimable invention. It is the schematic which shows only the component corresponding to one wheel among the absorber systems for vehicles of a present Example. It is sectional drawing of the 1st damping force generator shown in FIG. It is sectional drawing of the 2nd damping force generator shown in FIG. (A) It is a graph which shows the damping characteristic of the 1st damping force generator shown in FIG. (B) It is a graph which shows the damping characteristic of the 2nd damping force generator shown in FIG. It is a graph which shows the damping characteristic of the absorber system for vehicles of a present Example. It is a figure for demonstrating the effect by having provided the range with which the damping characteristic of a 1st damping force generator and the damping characteristic of a 2nd damping force generator overlap. It is a graph which shows the relationship between the hydraulic pressure difference of a rod side chamber and a non-rod side chamber, and the electric current supplied to a 2nd damping force generator. It is a flowchart which shows the damping force control program performed by the control apparatus shown in FIG. 10 is a flowchart showing a sprung acceleration-based damping force control subroutine executed in the damping force control program shown in FIG. 9. 10 is a flowchart showing a hydraulic pressure difference-based damping force control subroutine executed in the damping force control program shown in FIG. 9. It is a block diagram which shows the function of the control apparatus shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the claimable invention will be described in detail with reference to the drawings as modes for carrying out the claimable invention. In addition to the following examples, the claimable invention is implemented in various modes including various modifications and improvements based on the knowledge of those skilled in the art, including the mode described in the above [Mode of Invention]. can do. Moreover, it is also possible to constitute the modification of the following Example using the technical matter described in the description of each item of [Aspect of the Invention].

[A] Configuration of Vehicle Absorber System As shown in FIG. 1, a vehicle absorber system 10 that is an embodiment of the claimable invention includes four cylinders 14 provided corresponding to four wheels 12, and four of them. And a damping force control unit 16 for controlling the damping force with respect to expansion and contraction of the two cylinders 14. The damping force control unit 16 serves as a plurality of damping force generators that generate damping force for expansion / contraction of each cylinder 14 to be described later, and a control device that controls them to control damping force for expansion / contraction of each cylinder 14. ECU20 and the sensor used for control of damping force are comprised integrally. The damping force control unit 16 and each cylinder 14 are connected by piping, and hydraulic fluid flows between the damping force control unit 16 and each cylinder 14 as the cylinder 14 expands and contracts.

  As described above, the damping force control unit 16 includes a plurality of damping force generators corresponding to each of the four cylinders 14 that generate damping forces with respect to the expansion and contraction of the cylinders 14. In addition, since the structure corresponding to each cylinder in the damping force control unit 16 is the same, first, the component corresponding to one wheel 12 in the absorber system for a vehicle 10 is schematically shown. This will be described in detail with reference to FIG.

  As shown in FIG. 2, the cylinder 14 includes a housing 30, a piston 32 movably arranged in the vertical direction inside the housing 30, and one end (lower end) connected to the piston 32 and the other end. The (upper end) includes a piston rod 34 that extends upward from the housing 30. The housing 30 is connected to the lower arm, and the upper end portion of the piston rod 34 is connected to the mount portion. In other words, when the spring top and the spring bottom move relative to each other in the direction of separation (hereinafter, sometimes referred to as “rebound operation” or “rebound”), the extension and relative movement in the approaching direction (hereinafter referred to as “rebound operation”). , Sometimes referred to as “when bound” or “when bound”).

The housing 30 generally has a double structure, and has a bottomed main tube 40 and an outer tube 42 attached to the outer peripheral side thereof. The piston 32 is slidably disposed inside the main tube 40. And inside the main tube 40, the rod side chamber 44 and the anti-rod side chamber 46 which are two liquid chambers are defined by the piston 32. In addition, a buffer chamber (also referred to as a “reservoir”) 50 that stores hydraulic fluid is defined between the main tube 40 and the outer tube 42.

  An inter tube 60 is disposed in the housing 30 between the main tube 40 and the outer tube 42. An annular liquid passage 62 is defined between the inner peripheral surface of the intertube 60 and the outer peripheral surface of the main tube 40. A partition member 64 that partitions the bottom of the anti-rod side chamber 46 is provided at the inner bottom portion of the main tube 40, and a bottom liquid passage 66 is provided between the partition member 64 and the bottom wall of the main tube 40. Is formed.

  In the upper part of the main tube 40, a circulation hole 70 is provided for the circulation of hydraulic fluid between the liquid passage 62 and the rod side chamber 44. Further, a bottom portion circulation hole 72 is provided in a portion near the lower end of the main tube 40 for circulation of the working fluid between the buffer chamber 50 and the bottom portion liquid passage 66. At the lower part of the intertube 60, an outlet 74 that allows the hydraulic fluid to flow out from the fluid passage 54 to the damping force control unit 16 is provided. The outer tube 42 is provided with an inlet 76 that allows the working fluid to flow from the damping force control unit 16 into the buffer chamber 50.

  In the bounding operation of the cylinder 14, as indicated by a solid line arrow in FIG. 2, first, the working fluid flows into the rod side chamber 44 from the non-rod side chamber 46 through the check valve 80 provided in the piston 32. . Since the amount of the hydraulic fluid flowing into the rod side chamber 44 is larger than the volume that increases with the operation of the piston 32 in the rod side chamber 44, the rod side chamber 44 passes through the circulation hole 70 and the liquid passage 62 and The hydraulic fluid flows through the damping force control unit 16 into the buffer chamber 50. At this time, the damping force for the contraction of the cylinder 14, that is, the damping force for the bounce operation is generated by the resistance given to the flow of the hydraulic fluid by the damping force control unit 16.

  On the other hand, during the rebound operation, the hydraulic fluid flows out from the rod side chamber 44 into the buffer chamber 50 through the flow hole 70, the liquid passage 62, and the damping force control unit 16 as in the case of the bound operation. At that time, the damping force for the extension of the cylinder 14, that is, the damping force for the rebound operation is generated by the resistance given to the flow of the hydraulic fluid by the damping force control unit 16. As shown by a broken arrow in FIG. 2, the counter rod side chamber 42 of the cylinder 14 passes from the buffer chamber 50 through a bottom valve 72, a bottom liquid passage 66, and a check valve 82 provided in the partition member 64. Therefore, the hydraulic fluid flows in.

  A pipe 92 connects the outlet 74 of the cylinder 14 to the inlet 90 of the damping force control unit 16, and a pipe 96 connects the outlet 94 of the damping force control unit 16 to the inlet 76 of the cylinder 14. Connected by.

  The damping force control unit 16 includes a first channel 100 and a second channel 102 provided in parallel from the inlet 90 to the outlet 94 corresponding to each cylinder 14. The first flow path 100 has a switching valve 104 that switches between a state where the flow of hydraulic fluid in the first flow path 100 is allowed and a state where it is prohibited, and a resistance to the flow of hydraulic fluid to prevent expansion and contraction of the cylinder 14. A first damping force generator 106 that generates a damping force is provided. The switching valve 104 is a normally open on-off valve. Further, the second flow path is provided with a second damping force generator 108 which is another damping force generator. In other words, in this vehicle absorber system 10, two damping force generators 106 and 108 are provided for each cylinder 14. As will be described in detail later, these two damping force generators 106 and 108 are used. Thus, the damping force with respect to the expansion and contraction of each cylinder 14 is controlled.

  The damping force control unit 16 includes four switching valves 104, four first damping force generators 106, and two second damping force generators 108 corresponding to the four cylinders 14, respectively. It is.

  Moreover, ECU20 with which the damping force control unit 16 is provided controls damping force with respect to expansion / contraction of each cylinder 14 by controlling each damping force generator. The ECU 20 is mainly configured by a computer having a CPU, a ROM, a RAM, and the like. The ECU 20 controls the damping force generated by each damping force generator 106, 108 by controlling the current supplied from the battery [BAT] 110 to each damping force generator 106, 108.

The vehicle is provided with four sprung acceleration sensors [Gz] 112 that detect the vertical acceleration of each spring top of the vehicle body corresponding to each wheel 12, and these are connected to the computer of the ECU 20. Further, the damping force control unit 16 detects the hydraulic pressure of the four rod side chamber hydraulic pressure sensors [P _U ] 114 that detect the hydraulic pressure of the rod side chamber 44 and the hydraulic pressure of the non-rod side chamber 46 corresponding to each cylinder 14. The four anti-rod side chamber hydraulic pressure sensors [P _L ] 116 are also connected to the computer of the ECU 20. ECU20 shall control damping force based on the signal from those sensors. Incidentally, the character [] is a symbol used when the sensor or the like is shown in the drawing. In addition, the ROM included in the computer of the ECU 20 stores a program related to damping force control, various data, and the like.

[B] Configuration of Damping Force Generator (a) Configuration of First Damping Force Generator The configuration of the first damping force generator 106 will be briefly described below with reference to FIG. The first damping force generator 106 includes a main valve 120 for applying resistance to the hydraulic fluid passing through the first damping force generator 106 and a first solenoid valve 122 for adjusting the valve opening pressure of the main valve 120. It is an element, and is composed mainly of a so-called pilot-type solenoid valve.

  The main valve 120 and the first solenoid valve 122 are provided in a housing 130 having a generally covered cylindrical shape. In the housing 130, there is provided a main flow path 132 which is a main flow path through which hydraulic fluid flows when the cylinder 14 is expanded and contracted, as indicated by the dashed arrows in FIG. A main valve 120 is provided in the main flow path 132 and is urged in a seating direction by a compression coil spring 134. When the main valve 120 is opened, the main valve 120 allows the flow of the hydraulic fluid in the main flow path 132 and gives resistance to the flow of the hydraulic fluid.

  Further, a bypass path 140 that bypasses the main valve 120 is provided in the housing 130 as indicated by a solid arrow in FIG. The bypass passage 140 is provided with a fixed orifice 142, a pilot chamber 144, and a first solenoid valve 122 in order from the upstream side. The pilot chamber 144 causes the main valve 120 to have an internal pressure in a direction in which the main valve 120 is closed. That is, the main valve 120 has a force acting due to a differential pressure between the fluid pressure in the front chamber 146 and the fluid pressure in the pilot chamber 144, which is the fluid chamber on the front side (left side of the main valve 120 in FIG. When the urging force of the spring 134 is exceeded, the valve is opened. The fixed orifice 142 is provided so as to penetrate the main valve 120, and provides resistance to the flow of hydraulic fluid from the front chamber 146 to the pilot chamber 144.

  The first solenoid valve 122 is configured to include a valve movable body 150 and a coil 152 that generates an electromagnetic force for operating the valve movable body 150 when excited, and is downstream of the pilot chamber 144 in the bypass passage 140. On the side. The movable valve body 150 includes a poppet-type valve head 154, and the pilot chamber 144 can be opened and closed by the valve head 154 being attached to and detached from the valve seat 156. The valve movable body 150 is urged by a compression coil spring 158 in a direction in which the valve head 154 is separated. On the other hand, when the coil 152 is excited, a biasing force in a direction in which the valve head 154 is seated acts on the valve movable body 150.

  The first solenoid valve 122 can adjust the opening degree of the pilot chamber 144, in other words, the outflow amount from the pilot chamber 144 to the downstream side, from the above-described configuration. That is, the first solenoid valve 122 can adjust the valve opening pressure of the main valve 120 by adjusting the hydraulic pressure in the pilot chamber 144.

  If a failure occurs in which the first solenoid valve 122 cannot be energized, the valve head 154 is separated from the valve seat 156 by the spring 158, and the flow path 160 is blocked by the valve head 154. . A fail valve 162 is provided in the housing 130. When the flow path 160 is blocked by the valve head 154, the working fluid flows through the fail valve 162, and the flow of the working fluid is reduced. Resistance is given.

(B) Configuration of Second Damping Force Generator Next, the configuration of the second damping force generator 108 will be briefly described with reference to FIG. The second damping force generator 108 is a solenoid valve, and can be considered as a second solenoid valve. The second damping force generator 108 includes a hollow housing 160 and a plunger 172 provided in the housing 170 so as to be movable in the axial direction thereof. The left end of the housing 170 is formed by a covered cylindrical valve member 174. The valve member 174 divides the inside of the housing 170 into a first liquid chamber 176 and a second liquid chamber 178. Yes. The valve member 174 is provided with a communication hole 180 that penetrates in the axial direction and communicates the first liquid chamber 176 and the second liquid chamber 178. The second liquid chamber 178 of the housing 170 is opened to the left and is connected to the inlet 90 side. On the other hand, the first liquid chamber 176 of the housing 170 is connected to the outlet 94 side.

  The plunger 172 is housed in the first liquid chamber 176 of the housing 170 and can move in the axial direction in the first liquid chamber 176. The plunger 172 is rod-shaped on the left end side, and the tip thereof faces the communication hole 180. That is, the tip of the plunger 172 functions as a valve body, and the portion forming the communication hole 180 functions as a valve seat. And the communication hole 180 is closed because the front-end | tip of the plunger 172 sits on the valve seat. Plunger 172 is biased in a direction approaching the valve seat by a coil spring 182 disposed between the right end of housing 170.

  The second damping force generator 108 includes a coil 174 that generates an electromagnetic force for operating the plunger 162. When the coil 174 is excited, an electromagnetic force is generated in a direction opposite to the direction in which the plunger 102 is urged by the coil spring 120, that is, in the direction in which the plunger 102 is separated from the valve seat.

[C] Damping force against expansion / contraction of the cylinder (a) Damping force generated by the first damping force generator The first damping force generator 106 configured as described above has a damping characteristic as shown in FIG. It has become. When the relative motion speed v _st (hereinafter sometimes referred to as stroke speed) between the sprung portion and the unsprung portion is low, the main valve 120 is not opened, and the damping force F is applied to the main valve 120. It depends on the resistance to the flow of hydraulic fluid passing through the fixed orifice 142 provided. When the differential pressure between the front chamber 146 and the pilot chamber 144 increases and the main valve 120 opens, the damping force F depends on the resistance to the flow of hydraulic fluid that passes through the main valve 120. is there. The valve opening pressure of the main valve 120 depends on the magnitude of the current supplied to the coil 152 of the first solenoid valve 122. The larger the current, the smaller the opening of the pilot chamber 144 and the higher the hydraulic pressure in the pilot chamber 144. That is, the larger the energization current to the coil 152, the higher the valve opening pressure of the main valve 120, and the greater the damping force that is generated.

In the absorber system 10 of the present embodiment, in order to control the damping force generated by the first damping force generator 106, the first damping force generator 106 is supplied with a lower limit current I _1-MIN and an upper limit respectively. A current I ₁ between the current I ₁ -MAX is supplied. Then, the first damping force generator 106 can control the damping force F ₁ (I ₁ ) within the hatched range in FIG. 5A by supplying the current I _{1 in} that range. It is possible.

(B) Damping force generated by the second damping force generator On the other hand, the second damping force generator 108 has a damping characteristic as shown in FIG. The second damping force generator 108 is given resistance to the flow of hydraulic fluid that passes between the valve seat and the valve body, specifically, between the tip of the plunger 172 and the valve member 174. The magnitude of the resistance depends on the size of the gap between the valve seat and the valve body, that is, the degree of valve opening. The biasing force applied to the plunger 172 by the excitation of the coil 184 depends on the magnitude of the current supplied to the coil 184, and the degree of valve opening increases as the current increases. That is, it becomes easy to open the valve. Therefore, as the current supplied increases, the resistance given to the flow of hydraulic fluid decreases.

In the absorber system 10 of the present embodiment, in order to control the damping force generated by the second damping force generator 108, the second damping force generator 108 is supplied with a lower limit current I _2-MIN that is a set value. current I ₂ between the upper limit current I _2-MAX is supplied. Then, the second damping force generator 108 can control the damping force F ₂ (I ₂ ) within the hatched range in FIG. 5B by supplying the current I _{2 in} that range. It is possible.

(C) Relationship between damping forces generated by the two damping force generators As shown in FIG. 6, the first damping force generator 106 can change the damping force from the middle speed range to the high speed range of the stroke speed _vst. It is supposed to be generated. On the other hand, the second damping force generator 108 generates the damping force in a changeable range in the range where the first damping force generator 106 cannot generate the damping force, that is, in the low speed region of the stroke speed _vst. Yes. Therefore, according to the absorber system 10 of the present embodiment, the damping force with respect to the stroke of the cylinder 14 can be controlled in a wide speed range. The damping force generation characteristic of the first damping force generator 106 shown in FIG. 5A and the damping force generation characteristic of the second damping force generator 108 shown in FIG. These two damping force generators 106 and 108 are configured to overlap. Specifically, in the present absorber system 10, the damping force generated by the first damping force generator 106 depending on the fixed orifice 142 is within the range of the damping force generated by the second damping force generator 108. It is configured as such. Specifically, the damping force generated by the first damping force generator 106 depending on the fixed orifice 142 is slightly larger than the damping force generated by the second damping force generator 108 when the upper limit current I _2-MAX is applied. It is configured as such.

[D] Control of damping force (a) Sprung speed-based damping force control In the vehicle absorber system 10, control that suppresses vibration of the sprung portion of the vehicle is mainly executed. Specifically, the first damping force is generated so that a damping force suitable for suppressing the vibration of the sprung portion can be obtained based on the operating speed of the sprung portion in the vertical direction (hereinafter sometimes referred to as “sprung speed”). The supply current to the generator 106 or the second damping force generator 108 is controlled.

Specifically, a damping force appropriate for suppressing the vibration of the sprung portion, that is, a target damping force F ^{* that} is a target of the damping force generated by one of the two damping force generators 106 and 108 is expressed by the following equation. It is determined.
F ^* = ζ _S · v _S
By the way, v _S is the sprung absolute velocity, and ζ _S is a damping coefficient appropriate for suppressing the vibration of the sprung portion.

Then, the current supplied to the first damping force generator 106 or the second damping force generator 108 is controlled so that the determined target damping force F ^* is obtained with respect to the stroke speed _vst of the cylinder 14. is there.

However, the damping force that can be generated by each of the first damping force generator 106 and the second damping force generator 108 is in the range shown in FIG. It is comprised so that the damping force generator which generates may be switched. More specifically, as shown in FIG. 6, the actual stroke speed v _st of the cylinder 14 is higher than the target damping force corresponding stroke speed v _st ^* which is a stroke speed determined corresponding to the target damping force F ^*. In the case where the damping force is generated by the first damping force generator 106 and the actual stroke speed v _st is equal to or less than the target damping force corresponding stroke speed v _st ^* , the damping force is generated by the second damping force generator 108. It is supposed to be generated.

Specifically, first, based on the detection value of the sprung acceleration sensor 112, the actual stroke speed v that is the actual stroke speed of each cylinder 14 (for example, by the method described in JP-A-9-309315). _{st_r} is estimated. Hereinafter, the estimated actual stroke speed is referred to as an estimated stroke speed _{vst_r} . Then, the estimated stroke speed v _{st_r} is _compared with the target damping force corresponding stroke speed v _st ^* .

When the estimated stroke speed v _{st_r} is equal to or less than the target damping force corresponding stroke speed v _st ^* , the ECU 20 closes the switching valve 104 and prohibits the flow of hydraulic fluid to the first damping force generator 106. The supply current to the second damping force generator 108 is controlled so that the target damping force F ^* corresponding to the estimated stroke speed v _{st_r} is obtained. On the other hand, when the estimated stroke speed v _{st_r} is higher than the target damping force-corresponding stroke speed v _st ^* , the ECU 20 stops supplying current to the second damping force generator 108 and closes it, and the switching valve 104 is opened, the flow of hydraulic fluid to the first damping force generator 106 is allowed, and the target damping force F ^* corresponding to the stroke speed _vst is obtained to the first damping force generator 108. The supply current is controlled.

The relationship between the target damping force F ^* and the target damping force-corresponding stroke speed v _st ^* is shown in FIG. 6 by the dampening force generation characteristic of the first damping force generator 106 and the second damping force. The center of the generator 108 is set within the overlapping range. Specifically, the stroke speed v _st ^* corresponding to the target damping force is the lowest stroke speed at which the first damping force generator 106 can generate the target damping force F ^*, and the target damping force is determined by the second damping force generator 108. It is the center value of the highest stroke speed that can be generated. As a result, the absorber system 10 can continuously connect the damping force when switching between the first damping force generator 106 and the second damping force generator 108.

Further, as described above, in the present absorber system 110, since the estimated stroke speed v _{st_r} is estimated based on the sprung acceleration sensor 112, an error may occur in the estimated stroke speed v _{st_r} . For example, when the damping force generation characteristic of the first damping force generator 106 and the damping force generation characteristic of the second damping force generator 108 do not wrap, as shown in FIG. There is a risk of requesting a damping force in a range that the generator cannot generate. In such a case, a great variation occurs in the damping force actually generated. However, according to the present absorber system 10, as shown in FIG. 7B, since both of the two damping force generators are switched within a range in which the damping force can be generated, the above damping force is It is possible to avoid the situation that varies.

(B) _{Hydraulic Pressure Difference-Based} Damping Force Control As described above, in the present absorber system 10, the estimated stroke speed v _{st_r} is estimated based on the detection value of the sprung acceleration sensor 112. However, it is difficult to accurately estimate the stroke speed in the low speed range. Therefore, in the present absorber system 10, when the estimated stroke speed v _{St_r} is equal to or less than the set stroke speed v _0, instead of the sprung speed relying damping force control described above, hydraulic pressure and anti rod rod side chamber 44 of the cylinder 14 A hydraulic pressure difference-based damping force control for controlling the damping force based on the difference from the hydraulic pressure in the side chamber 46 is performed.

More specifically, as shown in FIG. 6, the lower limit current I _1-MIN is applied to the set stroke speed v ₀ so that the valve opening pressure of the main valve 120 of the first damping force generator 106 becomes the lowest. In this case, the stroke speed when the main valve 120 is opened is set. When the estimated stroke speed v _{st_r} is equal to or lower than the set stroke speed v ₀ , the switching valve 104 is closed to prohibit the flow of hydraulic fluid to the first damping force generator 106 and the second damping force generator 108. It controls the supply current.

Supplying current to the second damping force generator 108, a hydraulic P _U of the rod side chamber 44 which is detected by the rod-side chamber pressure sensor 114, the liquid anti-rod side chamber 46 detected by the counter-rod-side chamber pressure sensor 116 It is determined based on the difference Pd (= P _U −P _L ) from the pressure P _L. Specifically, the initial hydraulic pressure difference Pd _i is a hydraulic pressure difference when the ignition switch is turned ON are stored, the difference between the fluid pressure difference Pd and the initial hydraulic pressure difference Pd _i at the present time .DELTA.Pd (= Pd-Pd _i ) in accordance with the temporal change .DELTA.Pd ', the supply current I ₂ to the second damping force generator 108 is determined. The relationship between ΔPd ′ and the current I ₂ supplied to the second damping force generator 108 is as shown in FIG. 8, so that as ΔPd ′ increases, the damping force increases. the supply current I ₂ to the second damping force generator 108 is adapted to be smaller.

  Based on the hydraulic pressure difference, it is possible to estimate the operation of the cylinder 14 in the low speed range more accurately, and the absorber system 10 has an appropriate size for the expansion and contraction of the cylinder 14 in the low speed range. It is possible to generate a damping force.

  In the above-described two controls, the sprung speed-dependent damping force control and the hydraulic pressure-dependent damping force control, the expansion-side damping force and the contraction-side damping force were set to the same magnitude. The size may be different on the shrink side.

(C) Control program Control of the vehicle absorber system 10 of the present embodiment is performed by the ECU 20 executing a damping force control program shown in the flowchart of FIG. This program is repeatedly executed at a short time pitch (for example, several μsec to several tens μsec).

According to the damping force control program, first, in step 1 (hereinafter, “step” is abbreviated as “S”), the detection value of the sprung acceleration sensor 112 is acquired, and in S2, the sprung speed v _S is calculated. In addition, the actual stroke speed v _{st_r} is estimated in S3. Then, in S4, whether the estimated stroke speed v _{St_r} is higher than the set stroke speed v ₀ is determined. When the estimated stroke speed v _{st_r} is higher than the set stroke speed v ₀ , the sprung speed based damping force control is executed at S5, and when the estimated stroke speed v _{st_r} is less than or equal to the set stroke speed v ₀ , S6 The hydraulic pressure difference-based damping force control is executed.

The sprung speed-dependent damping force control in S5 is performed by executing a sprung speed-dependent damping force subroutine shown in the flowchart of FIG. In this subroutine, first, in S11, the target damping force F ^* (= ζ _S · v _S ) is determined based on the sprung speed v _S. Next, in S12, a target damping force corresponding stroke speed v _st ^* corresponding to the determined target damping force is acquired based on the map data. Then, in S13, it is determined whether or not the estimated stroke speed v _{st_r} is higher than the target damping force corresponding stroke speed v _st ^* .

When the estimated stroke speed v _{st_r} is higher than the target damping force-corresponding stroke speed v _st ^* , the first damping force generator 106 performs processing from S14 _onward in order to generate a damping force. Specifically, in S14, the current supply to the second damping force generator 108 is stopped (I ₂ ^* = 0) to be in the closed state, and in S15, the switching valve 104 is stopped from being supplied with the current in the open state. Thus, the flow of the hydraulic fluid to the first damping force generator 106 is allowed. Next, in S16, so that the target damping force F ^* is thus obtained which corresponds to the estimated stroke speed v _{St_r,} target supply current I ₁ ^* is determined to the first damping force generator 106.

On the other hand, when the estimated stroke speed v _{st — r} is equal to or less than the target damping force corresponding stroke speed v _st ^* , the processing of S 17 and _{subsequent steps} is performed so that the second damping force generator 108 generates a damping force. Specifically, in S <b> 17, the switching valve 104 is energized and closed, and the flow of hydraulic fluid to the first damping force generator 106 is prohibited. Next, in S18, the target supply current I ₂ ^* to the second damping force generator 108 is determined so that the target damping force F ^* corresponding to the estimated stroke speed v _{st — r} is obtained. This completes one execution of the sprung speed-dependent damping force subroutine.

Further, the hydraulic pressure-dependent damping force control in S6 is performed by executing the hydraulic pressure-dependent damping force subroutine shown in the flowchart of FIG. In this subroutine, first, in S21, the switching valve 104 is energized and closed, and the flow of hydraulic fluid to the first damping force generator 106 is prohibited. Then, in S22, the rod side chamber pressure is detected by the rod-side chamber pressure sensor 114 and counter-rod-side chamber pressure sensor 116 P _U and counter-rod-side chamber pressure P _L is obtained. Subsequently, in S23, a hydraulic pressure difference Pd (= P _U −P _L ) between the rod side chamber hydraulic pressure P _U and the anti-rod side chamber hydraulic pressure P _L is calculated. In S24, the hydraulic pressure difference Pd and the initial hydraulic pressure difference Pd _i are calculated. A difference ΔPd (= Pd−Pd _i ) is calculated. In subsequent S25, a process of differentiating the calculated difference ΔPd is performed, and a temporal change ΔPd ′ of the difference is obtained. In S26, the target supply current I ₁ ^* to the first damping force generator 106 corresponding to the temporal change ΔPd ′ of the difference is determined based on the map data shown in FIG. This completes one execution of the hydraulic pressure difference-based damping force subroutine.

  As described above, after the target supply current to the first damping force generator 106 and the target supply current to the second damping force generator 108 are determined, in S7 in the damping force control program, the first damping force generator 106, the second damping force generator 108, and the supply current to the switching valve 104 are controlled. This completes one execution of the damping force control program.

[D] Functional Configuration of ECU The ECU 20 as a control device that executes the control as described above can be considered to have various functional units that perform the various processes described above. More specifically, as shown in FIG. 12, the ECU 20 (i) based on the sprung speed, a target damping force determination unit 200 that determines a target damping force that is a target of the damping force with respect to the expansion and contraction of the cylinder 14, and ( ii) a sprung speed-based damping force control unit 202 that controls the supply current to the first damping force generator 106 and the second damping force generator 108 based on the sprung speed; and (iii) the rod side chamber of the cylinder 14. And a hydraulic pressure difference-based damping force control unit 204 that controls the supply current to the second damping force generator 108 based on the hydraulic pressure difference between the non-rod side chamber 44 and the non-rod side chamber 46. Further, the ECU 20 has an execution control switching unit 206 that switches between sprung speed-dependent damping force control and hydraulic pressure-dependent damping force control based on the actual stroke speed of the cylinder 14.

  In the ECU 20 of the vehicle absorber system 10, the target damping force determination unit 200 includes a portion that executes the processes of S 1 and S 2 of the damping force control program and S 11 of the sprung speed-dependent damping force control subroutine. Consists of. Further, the sprung speed speed-dependent damping force control unit 202 is configured to include a part that executes the processing of S12 and subsequent steps of the sprung speed speed-dependent damping force control subroutine. Furthermore, the hydraulic pressure difference-dependent damping force control unit 204 is configured to include a portion that executes a hydraulic pressure difference-based damping force control subroutine. Furthermore, the execution control switching unit 206 is configured to include a part that executes the processes of S3 and S4 of the damping force control program.

  Incidentally, the sprung speed-based damping force control unit 202 generates a damping force that generates a damping force based on the actual stroke speed of the cylinder 14 and a stroke speed corresponding to the target damping force determined corresponding to the target damping force. The generator switching unit 208 for switching the generator is provided. The generator switching unit 208 includes a part that executes the processes of S12 and S13 of the sprung speed-dependent damping force control subroutine.

10: Absorber system for vehicle 12: Wheel 14: Cylinder 16: Damping force control unit 20: ECU [control device] 30: Housing 32: Piston 34: Rod 44: Rod side chamber 46: Non-rod side chamber 50: Buffer chamber 90: Flow Inlet 92: Piping 94: Outlet 96: Piping 100: First flow path 102: Second flow path 104: Switching valve 106: First damping force generator 108: Second damping force generator [second solenoid valve] 112 : Sprung acceleration sensor [Gz] 114: rod side chamber hydraulic pressure sensor [P _U ] 116: anti-rod side chamber hydraulic pressure sensor [P _L ] 120: main valve [valve element] 122: first solenoid valve 132: main flow path 140 : Bypass path 142: Fixed orifice 144: Pilot chamber 150: Valve movable body 152: Coil 154: Valve head 156 Valve seat 172: Plunger 174: valve member 184: coil 200: target damping force determining section 202: sprung velocity relying damping force control unit 204: pressure difference relied damping force control unit

Claims (10)

A spring top of a vehicle having a housing for storing hydraulic fluid, a piston slidably disposed in the housing, a rod having one end connected to the piston and the other end extending from the housing And a cylinder which is arranged so as to be connected to the unsprung part and expands and contracts by relative movement between the unsprung part and the unsprung part,
A first damping force generator and a second damping force generator, which are provided in parallel with each other, each of which gives resistance to the flow of hydraulic fluid accompanying expansion and contraction of the cylinder so as to change the damping force with respect to the expansion and contraction of the cylinder; Two damping force generators;
A vehicle absorber system comprising: a control device that controls the damping force against expansion and contraction of the cylinder by controlling the first damping force generator and the second damping force generator;
The first damping force generator is
(a) a main flow path through which hydraulic fluid flows when the cylinder expands and contracts; (b) a main valve provided in the main flow path that generates a damping force by applying resistance to the flow of hydraulic fluid; and (c) A bypass passage provided so as to bypass the main valve; (d) a pilot chamber provided in the bypass passage for applying an internal pressure in a direction to close the main valve; and (e) a supply. And a first solenoid valve that adjusts the valve opening pressure of the main valve by changing the internal pressure of the pilot chamber in accordance with the current that is applied, and the valve opening pressure of the main valve is changed by the first solenoid valve Configured to change the magnitude of the damping force generated by
The second damping force generator is
It is a valve that generates a damping force by allowing the hydraulic fluid flowing along with the expansion and contraction of the cylinder to pass therethrough and giving resistance to the flow of the hydraulic fluid, and adjusts the degree of opening of the valve according to the supplied current. A vehicle absorber system mainly composed of a second solenoid valve that changes the magnitude of the damping force generated by the above. The vehicle absorber system is
A first flow path provided in parallel with each other, each of which is a flow path through which hydraulic fluid flows in one direction as the cylinder expands and contracts, and the first damping force generator is provided; and A second flow path provided with the second damping force generator;
The vehicle absorber system according to claim 1, further comprising: a switching valve that switches between a state in which the flow of the hydraulic fluid to the first flow path is allowed and a state in which the flow is prohibited.   3. The vehicle absorber according to claim 2, wherein the switching valve is an on-off valve provided in the first flow path, is a normally open valve, and the second solenoid valve is a normally closed valve. system. The first damping force generator is
A fixed orifice that is provided in the bypass and provides resistance to a flow of hydraulic fluid accompanying at least one of expansion and contraction of the cylinder;
The first solenoid valve is
It is provided downstream of the pilot chamber in the bypass passage, and changes the internal pressure of the pilot chamber by controlling the flow of hydraulic fluid from the pilot chamber to the downstream side of the bypass passage,
The vehicle absorber system is
The damping force generated by the first damping force generator depending on the fixed orifice is within the range of the damping force generated by the second damping force generator when the second solenoid valve is energized. The vehicle absorber system according to any one of claims 1 to 3, which is configured as follows. The control device is
A sprung speed-based damping force control unit that controls a supply current to the first solenoid valve and the second solenoid valve based on a sprung speed that is a vertical speed of the top of the spring;
A target damping force determination unit that determines a target damping force that is a target of a damping force for expansion and contraction of the cylinder based on the sprung speed,
The sprung speed-dependent damping force control unit is
When the actual stroke speed, which is the actual speed at which the cylinder expands and contracts, is equal to or less than the stroke speed corresponding to the target damping force, which is the speed at which the cylinder extends and contracts, corresponding to the magnitude of the target damping force, A damping force is generated by a second damping force generator, and control is performed so that a damping force is generated by the first damping force generator when the actual stroke speed is higher than the stroke speed corresponding to the target damping force. The vehicle absorber system according to any one of claims 4 to 4. The vehicle absorber system is
The range of the damping force generation characteristic of the first damping force generator when the first solenoid valve is energized and the damping force generation characteristic of the second damping force generator when the second solenoid valve is energized Is configured to partially overlap
The relation between the stroke speed corresponding to the target damping force and the damping force is set within a range where the damping force generation characteristics of the first damping force generator and the damping force generation characteristics of the second damping force generator overlap. 5. The vehicle absorber system according to 5. The control device is
A hydraulic pressure difference-based damping force control unit is configured to control the supply current to the second solenoid valve based on the hydraulic pressure difference between the rod side chamber and the anti-rod side chamber partitioned by the piston in the housing. The vehicle absorber system according to any one of claims 1 to 4. The control device further comprises:
A sprung speed-based damping force control unit that controls a current supplied to the first solenoid valve and the second solenoid valve based on a sprung speed that is a vertical speed of the upper part of the spring;
When the actual stroke speed, which is the actual speed at which the cylinder expands and contracts, is less than or equal to the set stroke speed, the supply current to the second solenoid valve is controlled by the hydraulic pressure difference-based damping force control unit, and the actual stroke speed is 8. The vehicle absorber system according to claim 7, wherein when the stroke speed is higher than the set stroke speed, a supply current to the second solenoid valve is controlled by the sprung speed-dependent damping force control. The set stroke speed is
In a state where hydraulic fluid does not flow to the second damping force generator and hydraulic fluid flows only to the first damping force generator, the first solenoid valve is supplied to the first solenoid valve so that the valve opening pressure of the main valve is minimized. The vehicle absorber system according to claim 8, wherein when the supply current is controlled, the vehicular absorber system is set to a stroke speed for generating a minimum valve opening pressure of the main valve. The vehicle absorber system is
Provided corresponding to each of the plurality of wheels, each of which is the cylinder, the plurality of first damping force generators and the plurality of cylinders that are the second damping force generators, the plurality of first damping force generators, and the plurality of wheels A second damping force generator;
The plurality of first damping force generators and the plurality of second damping force generators are configured as one unit, and each of the plurality of cylinders is connected to the unit by piping. 10. The vehicle absorber system according to any one of 9 above.

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