JP2012145171A - Damping force variable damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damping force variable damper, in which reduction of control power, improvement of controllability and the like are achieved.SOLUTION: In a piston 16, a pair of axial bores 31 each having a sector-shape cross section are bored with an interval of 180°, and a valve slot 33 having a circular cross section is formed in a central part in the axial direction. A valve plate 34 includes: a pair of arc-shape elastic valve parts 34a; and a pair of closed plate parts 34b respectively formed into a sector-shape and continued to each base end of both the elastic valves 34a. A piston rod 13 has a hollow structure, and a control rod 35 for transmitting driving force of an actuator 21 to the valve plate 34 is rotatably held in the hollow part 13b.

Description

  The present invention relates to a damping force variable damper used for a suspension of an automobile, and relates to a technique for realizing reduction of control power, improvement of controllability, and the like.

  Suspension is an important factor that affects the running stability of an automobile, and links (arms and rods) that support the wheels so that they can move up and down with respect to the vehicle body and impact from the road surface by bending. The main constituent members are the absorbing spring and the damper that attenuates the vibration of the spring. A damper for an automobile suspension includes a cylindrical cylinder filled with hydraulic oil and a piston rod with a piston sliding at the tip of the cylinder, and the hydraulic oil is moved along with the operation of the piston (piston rod). In general, a double cylinder type or a single cylinder type that moves between a plurality of oil chambers is generally used.

  In the cylindrical damper, a piston is generally provided with a communication hole or a valve plate, and when the hydraulic oil moves between oil chambers, a flow resistance is given to obtain a damping force. However, since such a damper has a constant damping characteristic, it is not possible to obtain riding comfort and running stability suitable for the road surface condition and the running condition. Therefore, by installing the contraction side and extension side valve plates made of magnetic material on the upper and lower surfaces of the piston, and by embedding an annular coil that generates a magnetic field in the piston, the amount of current flowing through the coil can be increased or decreased. There has been proposed a damping force variable damper that changes the strength of a magnetic field and thereby changes the valve opening characteristics (that is, damping force) of the valve plate steplessly (see Patent Document 1).

JP 2006-342955 A

  The damping force variable damper of Patent Document 1 has the following problems for the convenience of changing the valve opening characteristics of the valve plate by a magnetic field. That is, since the magnetic force by the coil is inversely proportional to the square of the distance between the coil and the valve plate, when the valve plate is largely opened by the fluid pressure of the hydraulic oil, the valve plate is less than when the valve plate is closed. A very large magnetic force is required to attract the piston toward the piston. Therefore, in this damping force variable damper, it is necessary to continue supplying a large amount of power to the coil even if the target damping force is constant, and it is not only necessary to increase the capacity of the in-vehicle battery, but also the power generation load of the alternator There was a problem of increasing (engine driving loss increased). In addition, when the valve plate is open, the magnetic force of the coil does not easily reach the valve plate, so it is difficult to accurately control the damping force, and there is a possibility that vibration or abnormal noise may be generated from the suspension due to sudden increase or decrease of the damping force. It was.

  The present invention has been made in view of such a background, and an object thereof is to provide a damping force variable damper that realizes reduction of control power, improvement of controllability, and the like.

  The damping force variable damper according to the present invention is connected to one of the vehicle body side member and the wheel side member, and reciprocates within the cylinder, and a cylindrical cylinder in which hydraulic oil is sealed. The cylinder is divided into a rod-side oil chamber and a piston-side oil chamber, and is formed in an axial hole that allows the hydraulic oil to flow between the rod-side oil chamber and the piston-side oil chamber, and an axially intermediate position. And a piston rod having a valve slot that opens to a side surface of the axial hole, and a piston rod that is connected to either the vehicle body side member or the wheel side member and that holds the piston at the tip thereof A valve plate that is movably held in the valve slot and protrudes and disappears in the axial hole, and a closing plate portion that faces the elastic valve portion with a predetermined gap. And a valve plate driving means for driving the valve plate, and the elastic valve portion changes in a protruding amount in the axial hole as the valve plate moves, and the shaft in the valve slot changes. The valve is opened by the hydraulic pressure of the hydraulic oil while being cantilevered by the opening end on the direction hole side.

  In the second aspect of the present invention, the valve plate is rotatably held in the valve slot around the axis of the piston as a rotation center.

  In the third aspect of the present invention, the elastic valve portion has a substantially arc shape when viewed in the axial direction of the piston, and a proximal end is connected to the closing plate portion.

  Further, in the fourth aspect of the present invention, the elastic valve portion is configured such that when the hydraulic oil flows from the rod side oil chamber into the piston side oil chamber, and from the piston side oil chamber to the rod side oil chamber. The valve opening resistance differs depending on the flow of the hydraulic oil.

  According to the present invention, a desired damping force can be obtained by the displacement of the valve plate while having a relatively simple and inexpensive configuration, so that it is possible to reduce control power and improve controllability. In addition, when the valve plate is rotatably held in the valve slot, a simple structure can be adopted as the valve plate driving means. Further, when the valve plate is made of a metal plate and the elastic valve portion has a substantially arc shape when viewed in the axial direction of the piston, and the base end is connected to the closing plate portion, the productivity is improved and the cost is reduced. Can be realized. Further, when the opening resistance of the elastic valve portion is different depending on the inflow direction of the hydraulic oil, the damping force can be made different between the contraction side and the extension side of the damper.

It is a perspective view of the rear suspension for cars concerning an embodiment. It is a longitudinal cross-sectional view of the damping force variable damper which concerns on embodiment. It is a disassembled perspective view of the piston and piston rod which concern on embodiment. It is a bottom view of the piston concerning an embodiment. It is a disassembled perspective view of the valve plate which concerns on embodiment. It is a principal part expanded longitudinal sectional view which shows the effect | action of embodiment. It is a principal part expanded longitudinal sectional view which shows the effect | action of embodiment. It is a principal part expanded longitudinal sectional view which shows the effect | action of embodiment.

  Hereinafter, an embodiment in which the present invention is applied to a tubular damping force variable damper for a four-wheel vehicle will be described in detail with reference to the drawings.

<< Configuration of 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 an electrically controlled damping force variable damper, and the damping force is variably controlled by an ECU 9 for damping force control installed in a trunk room or the like. Since the left and right dampers 6 are the same product, the description will be made only for the left one.

<Damper>
As shown in FIG. 2, the damper 6 according to the present embodiment is a monotube type (de carvone type), and has a cylindrical cylinder 12 filled with hydraulic oil, and slides in the axial direction with respect to the cylinder 12. A piston rod 13, a piston 16 that is attached to the tip of the piston rod 13 and divides the inside of the cylinder 12 into a rod-side oil chamber 14 and a piston-side oil chamber 15, and a high-pressure gas chamber 17 under the cylinder 12. A free piston 18, a cover 19 that prevents dust from adhering to the piston rod 13, and the like, a bump stop 20 that performs buffering at the time of full bound, and an electric actuator 21 that is used to drive a valve plate 34, which will be described later. Is the main component.

  The cylinder 12 is connected to the upper surface of the trailing arm 2 that is a wheel side member via a bolt 22 that is fitted into the eyepiece 12a at the lower end. The piston rod 13 is connected to a damper base (wheel house upper part) 25 that is a vehicle body side member through an upper and lower pair of bushes 23 and a nut 24. The actuator 21 is fixed to the upper portion of the upper bush 23 via a bracket 26.

<Damping force adjustment mechanism>
As shown in FIGS. 3 and 4, the piston 16 is formed with a pair of axial holes 31 having a fan-shaped cross section at intervals of 180 °, and a valve slot 33 having a circular cross section is formed in the center in the axial direction. Yes. The valve slot 33 has an opening 33a on the outer peripheral surface, and a disc-shaped valve plate 34 is inserted through the opening 33a. The piston rod 13 has a hollow structure, and a control rod 35 that transmits the driving force of the actuator 21 to the valve plate 34 is rotatably held in the hollow portion 13b.

  The valve plate 34 connects a pair of elastic valve portions 34a having an arc shape, a pair of closing plate portions 34b having a fan shape and continuing the base ends of both elastic valve portions 34a, and outer peripheral ends of the both closing plate portions 34b. And a rectangular hole 34d into which the drive projection 35a of the control rod 35 is fitted. As shown in FIG. 5, the valve plate 34 includes first to third plates 41 to 43 made of spring steel. The first to third plates 41 to 43 are integrated by spot welding to facilitate assembly, but may be integrated by bonding, rivets, or the like, or may not be integrated. .

  Like the valve plate 34, the first to third plates 41 to 43 include a pair of elastic valve portions 41a to 43a, a pair of closing plate portions 41b to 43b, a pair of connecting arc portions 41c to 43c, and a rectangular hole. 41d to 43d, but the gaps S1 to S3 between the tip and the closing plate portions 41b to 43b are different between the elastic valve portions 41a to 43a. That is, the gap S1 is the smallest, the gap S1 is set larger than the gap S2, and the gap S2 is set larger than the gap S3.

<< Operation of Embodiment >>
When the vehicle starts running, the ECU 9 estimates the motion state of the vehicle based on vehicle body acceleration (lateral acceleration and vertical acceleration), vehicle body speed, steering angle, and the like input from various sensors. Next, the ECU 9 sets a target damping force of the damper 6 according to the motion state of the automobile, and then outputs a drive current to the actuator 21. Then, the control rod 35 is rotationally driven by the actuator 21 and the valve plate 34 connected to the lower end of the control rod 35 rotates.

  When the target damping force is medium, as shown in FIG. 6A, the ECU 9 makes the occupation area of the elastic valve portion 34 a and the occupation area of the closing plate portion 34 b substantially the same in the axial hole 31. In addition, the rotational phase of the valve plate 34 (that is, the protruding amount of the elastic valve portion 34a) is controlled. The elastic valve portion 34a is cantilevered by the opening end 33b on the axial hole 31 side in the valve slot 33, and when the damper 6 is shortened (when bound), as shown in FIG. Only the elastic valve portion 41a of the first plate 41 is elastically deformed (ie, opened) by the fluid pressure, and the piston 16 descends with a relatively small resistance. Further, when the damper 6 is extended (rebounded), as shown in FIG. 6C, all of the elastic valve portions 41a to 43a of the first to third plates 41 to 43 are elasticized by the fluid pressure of the hydraulic oil. As a result of the deformation and the piston 16 ascending with a relatively large resistance, a moderate damping force is produced.

  Further, when the target damping force is high, as shown in FIG. 7A, the ECU 9 causes the area occupied by the elastic valve portion 34a to be smaller than the area occupied by the closing plate portion 34b in the axial hole 31. The rotational phase of the valve plate 34 is changed. Then, as shown in FIGS. 7B and 7C, both the elastic deformation of the elastic valve portion 41a when the damper 6 bounces and the elastic deformation of the elastic valve portions 41a to 43a when rebounding are less likely to occur, High damping force is generated.

  On the other hand, when the target damping force is low, as shown in FIG. 8 (a), the ECU 9 causes the occupied area of the elastic valve portion 34a to be larger than the occupied area of the closing plate portion 34b in the axial hole 31. The rotational phase of the valve plate 34 is changed. Then, as shown in FIGS. 8B and 8C, both the elastic deformation of the elastic valve portion 41a when the damper 6 bounces and the elastic deformation of the elastic valve portions 41a to 43a when rebounding easily occur. A low damping force is produced.

  In this embodiment, by adopting such a configuration, the stepless damping force control can be performed with high accuracy and stability while suppressing power consumption related to the control as compared with the conventional device using the electromagnetic force described above. Could be realized. Further, when the target damping force does not change, the actuator 21 does not drive the valve plate 34, so that power consumption is further reduced and wear of the valve plate 34 and the valve slot 33 is suppressed, so that the damper 6 Improved durability.

  This is the end of the description of the embodiment. However, aspects of the present invention are not limited to these. For example, in the above embodiment, the present invention is applied to a single-cylinder variable damping force damper used for a rear suspension. However, the present invention is applicable to a variable damping force damper for a front suspension or a multi-cylinder damping force. Naturally, it can also be applied to a variable damper. In the above embodiment, the valve slot is formed in the integral piston. However, the piston may be divided into two parts, the upper half and the lower half, and the valve plate may be sandwiched between the upper half and the lower half. In the above embodiment, the valve plate is composed of three spring steel plates. However, the valve plate may be composed of four or more plates, or one or two plates. You may make it comprise from a plate. Further, in the above embodiment, the elastic valve portion and the closing plate portion are driven to rotate the integral valve plate, but a valve plate in which the elastic valve portion is joined to the closing plate portion by spot welding or the like may be adopted. Alternatively, the valve plate may be driven linearly. In addition, the specific structure and shape of the damping force variable damper and the valve plate can be appropriately changed without departing from the gist of the present invention.

2 Trailing arm (wheel side member)
6 Damper (Damping force variable damper)
12 cylinder 13 piston rod 14 rod side oil chamber 15 piston side oil chamber 16 piston 21 actuator (valve plate driving means)
25 Damper base (vehicle body side member)
31 Axial hole 33 Valve slot 33b Open end 34 Valve plate 34a Elastic valve part 34b Closing plate part 35 Control rod 41 First plate 42 Second plate 43 Third plate

Claims (4)

A cylindrical cylinder connected to one of the vehicle body side member and the wheel side member, and filled with hydraulic oil therein,
Axial direction that reciprocates in the cylinder, divides the cylinder into a rod side oil chamber and a piston side oil chamber, and distributes the hydraulic oil between the rod side oil chamber and the piston side oil chamber A cylindrical piston having a hole and a valve slot formed at an axially intermediate position and opening on a side surface of the axial hole;
A piston rod connected to the other of the vehicle body side member and the wheel side member, and holding the piston at its tip;
A valve plate having an elastic valve portion that is movably held in the valve slot and protrudes and disappears in the axial hole, and a closing plate portion facing the elastic valve portion with a predetermined gap;
Valve plate driving means for driving the valve plate,
The elastic valve portion changes in the amount of protrusion in the axial hole with the movement of the valve plate, and the hydraulic oil is cantilevered by the opening end of the valve slot on the axial hole side. The damping force variable damper is characterized in that the valve is opened by the fluid pressure.   2. The variable damping force damper according to claim 1, wherein the valve plate is rotatably held in the valve slot with the axis of the piston as a rotation center.   The damping force variable damper according to claim 2, wherein the elastic valve portion has a substantially arc shape when viewed in the axial direction of the piston, and a base end thereof is connected to the closing plate portion.   The elastic valve portion is formed when the hydraulic oil flows from the rod side oil chamber to the piston side oil chamber and when the hydraulic oil flows from the piston side oil chamber to the rod side oil chamber. The damping force variable damper according to any one of claims 1 to 3, wherein the valve opening resistance is different.

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