JP2008168709A - Damping force variable damper system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force variable damper system capable of causing a damping force variable damper to generate predetermined damping force temporarily even when feeding of electricity is not controlled due to a defect of a controller. <P>SOLUTION: A positive electrode of a capacitor 43 is connected with a power supply terminal Tp side through a switch 44 and an inductor 45, and its negative electrode is connected with a grounding terminal Te side. The switch 44 is a solenoid-incorporating type switch, and exciting current is supplied into it only when current is normally supplied into each MLVs 32a-32d to connect a power supply terminal Tp with the capacitor 43. If current is not normally supplied into each MLVs 32a-32d, supply of exciting current into the switch 44 is shut off, and its contacts are switched by spring force of the incorporated spring to connect the capacitor 43 with the MLVs 32a-32d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a damping force variable damper system. Specifically, even when power supply control is not performed due to a failure of a control device or the like, a predetermined damping force can be temporarily generated in a damping force variable damper. It relates to technology that can be used.

  Suspension is an important factor that affects the driving stability and ride comfort of an automobile. Links (arms and rods) that support the wheels to move up and down with respect to the vehicle body and the impact from the road surface due to the bending of the links. The main components are a spring that absorbs vibrations and the like, and a damper that attenuates vertical vibrations of the vehicle body. The suspension damper includes a cylindrical cylinder tube filled with hydraulic oil and a piston rod mounted at the tip of a piston that slides within the cylinder tube. As the piston (piston rod) moves, A cylindrical shape that employs a structure for moving hydraulic oil between a plurality of oil chambers is widely adopted.

2. Description of the Related Art In recent years, various damping force variable dampers that variably control the damping force according to the motion state of an automobile have been developed as an improvement in the characteristics of a cylindrical damper. As the damping force variable damper, a mechanical type in which a rotary valve that changes the orifice area is provided on the piston and this rotary valve is driven to rotate by an actuator has been the mainstream, but simplification of the configuration and improvement of responsiveness etc. In order to achieve this, there has been developed a technique in which a magnetorheological fluid is used as hydraulic oil and the viscosity of the magnetorheological fluid is controlled by a magnetorheological valve provided on a piston (see Patent Document 1).
JP 2006-77789 A

  In the damping force variable damper using the magnetorheological fluid, there is a possibility that the following problems may occur due to the absence of the mechanical damping mechanism. That is, the magnetic fluid valve described above is operated by a current supplied from an ECU (electronic control unit). However, when a current is supplied due to a failure of an electronic component constituting the ECU or a cut of a wire, the moment Therefore, the damping force cannot be obtained. And when such a situation occurs at the time of driving, even if a warning light or a warning sound is given, the ride comfort and steering stability are drastically impaired, so the driver feels uneasy There was a problem.

  The present invention has been made in view of such a background, and even when power supply control is not performed due to a failure of a control device or the like, a predetermined damping force can be temporarily generated in the damping force variable damper. An object of the present invention is to provide a damper system having a variable damping force.

  A damping force variable damper system according to a first aspect of the present invention includes a cylinder tube that is filled with a magnetic fluid or a magnetorheological fluid and that is connected to one of a vehicle body side member and a wheel side member; A piston having a communication hole that divides the liquid fluid into the first liquid chamber and the second liquid chamber and allows the magnetic fluid or the magnetorheological fluid to flow between the first liquid chamber and the second liquid chamber; A piston rod that connects the other of the wheel side member and the wheel side member to the piston, and a magnetic field application that applies a magnetic field to the magnetic fluid or the magnetorheological fluid that passes through the communication hole in accordance with an external electric input. And a magnetic field applying hand using electric power supplied from a vehicle power supply to generate a predetermined damping force in the variable damping force damper. Power supply control means for performing power supply control to the power supply, and power storage means for supplying predetermined power to the magnetic field application means when power supply control to the magnetic field application means is no longer performed by the power supply control means. It is characterized by.

  According to a second aspect of the present invention, in the damping force variable damper system according to the first aspect, the power storage means is a capacitor, and power supply control to the magnetic field applying means is performed by the power supply control means. Switch means for supplying electric power from the capacitor to the magnetic field applying means when the electric power supply to the magnetic field applying means is not performed by the electric power supply control means while charging the capacitor from the vehicle power supply Is further provided.

  According to a third aspect of the present invention, in the damping force variable damper system according to the second aspect, an inductor or a resistor is interposed between the capacitor and the magnetic field applying means.

  According to a fourth aspect of the present invention, in the damping force variable damper system according to the second or third aspect, the two poles of the capacitor are connected by a discharge circuit including a resistor having a predetermined resistance value. Features.

  According to the first aspect of the present invention, even when power supply control to the magnetic field applying means is not performed due to failure of the power supply control means or disconnection of the electric harness, current is supplied from the power storage means to the magnetic field applying means. The damping force variable damper generates a damping force over a predetermined time. As a result, the driver can decelerate the vehicle and stop it at a safe place, or drive the vehicle at a low speed and go to a maintenance shop or the like. Further, according to the invention of claim 2, the durability of the system is improved and the maintenance of the system becomes almost unnecessary as compared with the case where a storage battery or the like is used. According to the invention of claim 3, it is difficult to supply an excessive current from the capacitor to the magnetic field applying means, and the damping force of the damping force variable damper can be maintained for a relatively long time. According to the fourth aspect of the present invention, it is difficult to generate a spark due to a short circuit of the capacitor during system maintenance.

  Hereinafter, an embodiment in which the present invention is applied to a rear suspension of a four-wheel vehicle will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view of a rear suspension according to the embodiment, FIG. 2 is a longitudinal sectional view of a damper according to the first embodiment, and FIG. 3 is an MLV (Magnetizable Liquid Valve) according to the first embodiment. 4) is a schematic structural diagram of the damper control circuit according to the first embodiment.

<< Configuration of First Embodiment >>
<Suspension>
As shown in FIG. 1, the rear suspension 1 of the present embodiment is a so-called H-type torsion beam suspension, and the torsion beam 4 that connects the left and right trailing arms 2 and 3 and the intermediate portion between the trailing arms 2 and 3. The left and right rear wheels 7 and 8 are suspended from a pair of left and right coil springs 5 and a pair of left and right dampers 6 as suspension springs. The damper 6 is a damping force variable damper using MRF (Magneto-Rheological Fluid) as a working fluid, and the damping force is variably controlled by an ECU 9 installed in a trunk room or the like. In addition, although the damping force variable type damper is installed also in the front suspension, explanation and illustration of the installation form are omitted in this embodiment.

<Damper>
As shown in FIG. 2, the damper 6 of the present embodiment is a monotube type (de carvone type), and has a cylindrical cylinder tube 12 filled with MRF and an axial direction with respect to the cylinder tube 12. A piston rod 13 that slides, a piston 16 that is attached to the tip of the piston rod 13 and divides the inside of the cylinder tube 12 into an upper oil chamber 14 and a lower oil chamber 15, and a high-pressure gas chamber 17 under the cylinder tube 12. The main components are a free piston 18 that is defined, a cover 19 that prevents dust from adhering to the piston rod 13 and the like, and a bump stop 20 that performs buffering at the time of full bouncing.

  The cylinder tube 12 is connected to the upper surface of the trailing arm 2 that is a wheel side member via a bolt 21 that is inserted into the lower eyepiece 12a. Further, the piston rod 13 has a pair of upper and lower bushes 22 and a nut 23, and a stud 13a at the upper end thereof is connected to a damper base (wheel house upper part) 24 that is a vehicle body side member.

  As shown in FIG. 3, the piston 16 is provided with a communication hole 31 that allows the upper oil chamber 14 and the lower oil chamber 15 to communicate with each other, and an MLV (magnetic field applying means) 32 that is disposed inside the communication hole 31. It has been. When an electric current is supplied from the ECU 9 to the MLV 32, a magnetic field (a magnetic flux is indicated by an arrow in FIG. 3) is applied to the MRF flowing through the communication hole 31, and the ferromagnetic fine particles form a chain cluster. The apparent viscosity of the MRF passing through the inside (hereinafter simply referred to as viscosity) increases.

<ECU>
The ECU 9 of the first embodiment is composed of a CPU, ROM, RAM, peripheral circuit, input / output interface, various drivers, etc. (not shown), a power supply terminal Tp connected to the positive side of the battery power supply B, and a battery power supply B. And a ground terminal Te connected to the negative electrode side. A fuse F is interposed between the battery power supply B and the power supply terminal Tp.

  In the ECU 9, four current control circuits (power feeding control means) 41a to 41d connected to the power supply terminal Tp and the ground terminal Te are installed, and these current control circuits 41a are based on a current supply command from the CPU. Current is supplied to the corresponding MLVs 32a to 32d of the damper 6 from .about.41d. A fail safe relay 42 is interposed between the power supply terminal Tp and the current control circuits 41a to 41d. When the ignition key of the automobile is turned off or the CPU of the ECU 9 is stopped, the fail safe relay 42 is opened. As a result, the power supply to the current control circuits 41a to 41d is stopped.

<Storage circuit>
In the ECU 9, a capacitor (power storage means) 43 such as an electric double layer capacitor is installed between the power supply terminal Tp and the ground terminal Te. The capacitor 43 of the present embodiment has its positive electrode connected to the power supply terminal Tp side via the switch 44 and the inductor 45, and its negative electrode connected to the ground terminal Te side. The switch 44 is a solenoid built-in switch, and an excitation current is supplied only when the ECU 9 operates normally and current is normally supplied from the current control circuits 41a to 41d to the MLVs 32a to 32d. The power supply terminal Tp and the capacitor 43 are connected. Further, when the operation of the ECU 9 is stopped or the current is not normally supplied from the current control circuits 41a to 41d to each of the MLVs 32a to 32d, the switch 44 is not supplied with the excitation current, and the built-in spring The capacitor 43 and the MLVs 32a to 32d are connected by switching the contact point by the spring force. A diode 46 for preventing a backflow of current is interposed between the switch 44 and each of the MLVs 32a to 32d. In this power storage circuit, a resistor may be used instead of the inductor 45.

<< Operation of First Embodiment >>
When the automobile starts traveling, the ECU 9 rotates the vehicle body acceleration obtained from the longitudinal G sensor, the lateral G sensor, and the vertical G sensor, the vehicle body speed inputted from the vehicle speed sensor, and the rotation of each wheel obtained from the wheel speed sensor. Based on the speed, the steering speed input from the steering angle sensor, etc., after setting the target damping force of each damper 6 (that is, the target supply current to each MLV 32a to 32d), a current supply command is issued to the current control circuits 41a to 41d. Output. As a result, an appropriate current is supplied to the MLVs 32a to 32d of each damper 6, and the damping force of the damper 6 is always adjusted to an optimum value in accordance with the running state of the automobile. A comfortable ride is achieved at a high level. When the vehicle is traveling, the power supply terminal Tp and the capacitor 43 are connected by the switch 44, so that a predetermined amount of charge is always stored in the capacitor 43.

  On the other hand, when the automobile is running, the fuse F may be blown, the ECU 9 may be broken, the electrical harness may be disconnected, and the like, and current may not be supplied to all or part of the MLVs 32a to 32d. In this case, the driver is informed of the abnormality by turning on the warning light or sounding the warning sound, the fail safe relay 42 is opened, the power supply to the current control circuits 41a to 41d is cut off, and the exciting current to the switch 44 is further stopped. The capacitor 43 and the MLVs 32a to 32d are connected by the switch 44. Then, the electric charge stored in the capacitor 43 is gradually discharged to each of the MLVs 32a to 32d through the inductor 45, and the damper 6 generates a damping force for a predetermined time.

In the case of this embodiment, as shown in FIG. 5, when a failure occurs, a current larger than the current An that generates a damping force equivalent to that of a mechanical damper is supplied to the MLVs 32a to 32d over a predetermined time t (for example, several seconds). Supplied. As a result, the driver can park the car in a safety zone or roadside zone when driving on an expressway, etc., and wait for assistance, or drive the car at a low speed when driving in an urban area, etc. It becomes possible.
[Second Embodiment]
The overall configuration of the second embodiment is the same as that of the first embodiment described above, but the configuration of the storage circuit is different. That is, in the ECU 9 of the second embodiment, there are a voltage monitoring circuit 51 connected to the positive side and the negative side of the capacitor 43, and a discharge circuit 52 that connects the upstream side of the inductor 45 and the downstream side of the capacitor 43. Furthermore, it is installed.

  The voltage monitoring circuit 51 monitors the charging / discharging state of the capacitor 43. When the charging / discharging state of the capacitor 43 is abnormal, a warning display is displayed on the instrument panel based on the output signal from the voltage monitoring circuit 51. The driver can request a repair shop or the like for repair. In addition, the discharge circuit includes a register 53, and by gradually discharging the capacitor 43 when the automobile is stopped, a tool or the like is accidentally brought into contact with the capacitor 43 when a maintenance worker or a car dismantling worker opens the ECU 9. Even in such a case, the occurrence of sparks is suppressed.

  This is the end of the description of specific embodiments. However, aspects of the present invention are not limited to these embodiments. For example, although the above embodiment is an application of the present invention to a damping force variable damper system using a magnetorheological fluid, it may be applied to a damping force variable damper system using a magnetic fluid. In the above embodiment, the capacitor is used as the power storage means. However, other types of power storage means such as a storage battery may be adopted. In the above embodiment, the capacitor is built in the ECU. However, the ECU and the capacitor may be separated. In addition, as long as it does not deviate from the gist of the present invention, the specific configuration of the damper control circuit, the power storage circuit, and the like can be changed as appropriate.

It is a perspective view of the rear suspension concerning an embodiment. It is a longitudinal cross-sectional view of the damper which concerns on embodiment. It is a schematic structure figure of MLV concerning an embodiment. It is a principal part block diagram of the damper control circuit which concerns on 1st Embodiment. It is a graph for demonstrating the effect | action of 1st Embodiment. It is a principal part block diagram of the damper control circuit which concerns on 2nd Embodiment.

Explanation of symbols

6 Damper 12 Cylinder tube 13 Piston rod 14 Upper oil chamber 15 Lower oil chamber 16 Piston 31 Communication hole 32 MLV (magnetic field applying means)
41 Current control circuit (power supply control means)
43 Capacitor (electric storage means)
44 switch (switch means)
45 Inductor 51 Voltage Monitoring Circuit 52 Discharge Circuit 53 Register B Battery Power Supply (Vehicle Power Supply)

Claims (4)

A cylinder tube filled with a magnetic fluid or a magnetorheological fluid and connected to one of a vehicle body side member and a wheel side member, the cylinder tube being partitioned into a first liquid chamber and a second liquid chamber, and A piston having a communication hole through which a magnetic fluid or a magnetorheological fluid flows between the first liquid chamber and the second liquid chamber, and either the vehicle body side member or the wheel side member is used as the piston. A damping force variable damper having a piston rod to be connected and a magnetic field applying means for applying a magnetic field to the magnetic fluid or the magnetorheological fluid passing through the communication hole in response to an electrical input from the outside;
Power supply control means for performing power supply control to the magnetic field applying means using electric power supplied from a vehicle power source in order to generate a predetermined damping force in the damping force variable damper;
A damping force variable damper system comprising: a power storage unit configured to supply predetermined power to the magnetic field application unit when the power supply control unit does not perform power supply control to the magnetic field application unit. The power storage means is a capacitor;
When power supply control to the magnetic field application means is performed by the power supply control means, the power supply control to the magnetic field application means is performed by the power supply control means while charging the capacitor from the vehicle power supply. The damping force variable damper system according to claim 1, further comprising switch means for supplying electric power from the capacitor to the magnetic field applying means when the capacitor disappears.   The variable damping force damper system according to claim 2, wherein an inductor or a resistor is interposed between the capacitor and the magnetic field applying means.   4. The damping force variable damper system according to claim 2, wherein both poles of the capacitor are connected by a discharge circuit including a resistor having a predetermined resistance value. 5.

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