JP2008175247A - Damping force adjustable damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a damping force adjustable damper to be able to reduce the size and weight, and to facilitate the manufacturing, etc., of a piston. <P>SOLUTION: The piston 16 comprises an outer yoke 31 whose outer peripheral surface is slid with the inner wall of a cylinder 12, an inner yoke 32 arranged in the outer yoke 31, six gap spacers 33 interposed between the outer yoke 31 and the inner yoke 32, an MLV coil 34 externally fitted in the axial center of the inner yoke 32, and a thermosensitive shut-off valve 35 installed at the lower surface of the inner yoke 32 as main components. The inner yoke 32, which is made of a ferromagnetic material in the same way as the outer yoke 31, is also two-divided into a first inner yoke 41 to form the upper part, and a second yoke 42 to form the lower part, and fastened/incorporated by three screws 43, clamping the outer yoke 31 via the cap spacer 33. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a telescopic damping force variable damper that constitutes a suspension for an automobile, and more particularly, to a technique for realizing a reduction in size and weight of a piston, ease of manufacture, and the like.

  2. Description of the Related Art In recent years, various types of damping force variable dampers capable of variable damping force control have been developed for cylindrical dampers used in automobile suspensions in order to improve riding comfort and steering stability. 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 a technology in which a magnetorheological fluid is used as a working fluid and the viscosity of the magnetorheological fluid is controlled by a magnetorheological valve formed integrally with a piston (see Patent Document 1).

In the damping force variable damper of Patent Document 1, the piston has a cylindrical inner yoke with a coil wound around its outer periphery, a pair of end plates disposed at both ends of the inner yoke, and a cylindrical shape that houses the inner yoke and both end plates. The outer yoke is mainly composed of. Both the inner yoke and the outer yoke are made of a ferromagnetic material, and are held by the end plate to form an annular flow path therebetween. The end plate is a disc-shaped material made of a non-magnetic material, and includes a plurality of arc-shaped holes that communicate with the annular flow path, an annular recess that engages with the protrusion at the inner yoke end, and a piston rod fixing pin. And an annular groove with which the ring engages. Further, the inner yoke and the end plate are fixed by caulking the outer edges of both ends of the outer yoke.
US Pat. No. 6,260,675

  In the damping force variable damper disclosed in Patent Document 1, since relatively thick end plates are disposed at both ends of the inner yoke, it is inevitable that the weight and axial length of the piston increase, and the operability of the damper is improved. It was difficult to achieve compactness. In addition, since it is necessary to crimp the end of the outer yoke when assembling the piston, it is necessary to install a large device such as a press device on the production line, and there are problems that the piston cannot be easily disassembled during recycling. It was. Furthermore, since a cylindrical inner yoke and a cylindrical outer yoke are employed, it has been impossible to increase the thickness of the outer yoke near the coil in order to prevent magnetic saturation.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a damping force variable damper that realizes downsizing, facilitation of manufacture, and the like of a piston.

  The invention according to claim 1 is a cylinder filled with a magnetic fluid or a magnetorheological fluid and connected to one of the vehicle body side member and the wheel side member, and the cylinder is connected to one side liquid chamber and the other side liquid chamber. A piston formed with an annular flow path that divides the magnetic fluid or the magnetorheological fluid between the one-side liquid chamber and the other-side liquid chamber, and either the vehicle body-side member or the wheel-side member A damper having a piston rod that connects the other to the piston, and a damping force variable damper in which a damping force is controlled by applying a magnetic field to the magnetic fluid or the magnetorheological fluid passing through the annular flow path. The piston is installed with an outer yoke forming an outer peripheral side portion of the piston and a predetermined gap inside the outer yoke, and an inner passage defining the annular flow path between the outer yoke and the outer yoke. An outer yoke, a coil held by the inner yoke and used for forming the magnetic field, and a gap spacer interposed between the outer yoke and the inner yoke and used for forming the gap. One of the inner yoke and the inner yoke is divided in the axial direction so as to sandwich the other through the gap spacer, and is fastened / integrated by a fastening member.

  According to a second aspect of the present invention, in the damping force variable damper according to the first aspect, the gap formed between the outer yoke and the inner yoke is enlarged in diameter from the substantially axial center of the piston toward both ends. It is characterized by being formed along a taper.

  According to the damping force variable damper of the first aspect, the thick end plate is unnecessary, and the physique and weight of the piston are greatly reduced. Further, a large-scale device such as a press device is not necessary for manufacturing the piston, so that the equipment cost can be reduced and the piston can be easily disassembled at the time of recycling. According to the damping force variable damper of claim 2, magnetic saturation is hardly caused by increasing the thickness of the outer yoke in the vicinity of the coil, and heat generation during energization is reduced by reducing the coil diameter. .

  Hereinafter, two embodiments 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]
1 is a perspective view of a rear suspension according to the first embodiment, FIG. 2 is a longitudinal sectional view of a damper according to the first embodiment, and FIG. 3 is an enlarged view of a portion III in FIG. FIG. 5 is a bottom view of the piston according to the first embodiment, and FIG. 5 is a developed perspective view of the piston according to the first embodiment.

<< Configuration of First Embodiment >>
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.

<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 12 filled with MRF, and slides in the axial direction with respect to the cylinder 12. A piston rod 13 that is attached to the tip of the piston rod 13, a piston 16 that divides the inside of the cylinder 12 into an upper liquid chamber (one side liquid chamber) 14 and a lower liquid chamber (other side liquid chamber) 15, and the cylinder 12 The main components are a free piston 18 that defines a high-pressure gas chamber 17 in the lower portion of the cylinder, a cover 19 that prevents dust from adhering to the piston rod 13 and the like, and a bump stop 20 that performs buffering during full bouncing.

  The cylinder 12 is connected to the upper surface of the trailing arm 2 that is a wheel side member via a bolt 21 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) 24 which is a vehicle body side member through an upper and lower pair of bushes 22 and a nut 23.

<Piston>
The piston 16 is integrated with an MLV (Magnetizable Liquid Valve). As shown in FIGS. 3 to 5, an outer yoke 31 whose outer peripheral surface is in sliding contact with the inner wall surface of the cylinder 12, An inner yoke 32 disposed on the inner side, six gap spacers 33 interposed between the outer yoke 31 and the inner yoke 32, and an MLV coil (magnetic field applying means) 34 externally fitted to the axially central portion of the inner yoke 32 The temperature sensitive shut-off valve 35 provided on the lower surface of the inner yoke 32 is a main component.

  The outer yoke 31 is made of a ferromagnetic material such as ferrite, and has a substantially cylindrical shape as shown in FIG. 5, but a relatively small straight formed at the center in the axial direction on the inner peripheral side thereof. It has a surface 31a and upper and lower tapered surfaces 31b, 31c formed in a shape continuous with the straight surface 31a. Both the tapered surfaces 31b and 31c are expanded toward the end portion of the outer yoke 31 with a constant diameter expansion rate.

  The inner yoke 32 is also made of a ferromagnetic material like the outer yoke 31, but is divided into a first inner yoke 41 that forms the upper part and a second inner yoke 42 that forms the lower part, and the outer yoke 31 is separated via the gap spacer 33. It is fastened / integrated by three screws 43 in a sandwiched state. As shown in FIG. 5, the first inner yoke 41 includes a tapered surface 41 a that faces the tapered surface 31 b of the outer yoke 31 with a gap s, and a through hole 41 b through which the lower screw shaft 13 b of the piston rod 13 is inserted. Yes. On the other hand, the second inner yoke 42 has a tapered surface 42a that faces the tapered surface 31c of the outer yoke 31 with a gap s, and a screw hole 42b into which the lower screw shaft 13b of the piston rod 13 is screwed. To bypass the upper liquid chamber 14 and the lower liquid chamber 15, three bypass flow paths 44 penetrate through the inner yoke 32 in the axial direction at 120 ° angular intervals.

  The gap spacer 33 is a cylindrical member made of a non-magnetic aluminum alloy (duralumin), and three gap spacers 33 are vertically arranged at equal angular intervals (120 ° intervals) to maintain a gap between the outer yoke 31 and the inner yoke 32. It is arranged one by one. The gap spacer 33 is fixed to the outer yoke 31 by adhesion or the like, and engages with engaging recesses 41 c and 42 c formed on both inner yokes 41 and 42 of the piston 16.

  The MLV coil 34 is formed by winding a conducting wire in a cylindrical shape and resin-molding, and is fitted on the upper part of the second inner yoke 42. The outer peripheral surface of the MLV coil 34 is opposed to the straight surface 31a of the outer yoke 31 with a gap s. As a result, an annular flow path 45 through which the MRF flows is formed between the inner yoke 32 and the MLV coil 34 and the outer yoke 31. The MLV coil 34 is supplied with an exciting current from the ECU 9 via a wiring (not shown).

  As shown in FIG. 4, the temperature sensitive shut-off valve 35 rotates a valve body 52 rotatably supported by the second inner yoke 42 via a pivot screw 51, and rotates the valve body 52 counterclockwise in the figure. The shape memory spring 53 and a bias spring 54 that constantly urges the valve body 52 clockwise in the drawing are configured. The valve body 52 includes a pair of spring engagements in which three closing pieces 52a for closing the bypass flow path 44 of the inner yoke 32 when engaged counterclockwise, and one ends of the shape memory spring 53 and the bias spring 54 are engaged. It has a combination piece 52b, 52c and a stopper piece 52d that is used to regulate the rotation range. The shape memory spring 53 is a spring made of a shape memory alloy (in this embodiment, a titanium-nickel alloy), and contracts when the temperature becomes higher than a predetermined temperature (for example, 30 to 40 ° C.), and the spring of the bias spring 54 The valve body 52 is rotated by overcoming the force. In FIG. 4, a member denoted by reference numeral 55 is a locking pin that locks the other ends of the shape memory spring 53 and the bias spring 54 to the inner yoke 32, and is press-fitted / integrated with the second inner yoke 42. Further, members denoted by reference numeral 56 are a pair of stopper pins with which the stopper piece 52d abuts when the valve body 52 rotates, and these are also press-fitted / integrated with the second inner yoke 42.

<< Operation of First Embodiment >>
In the damper 6 of the present embodiment, by adopting the above-described configuration, the weight and the axial length of the piston 16 are significantly reduced as compared with the conventional one using the end plate, and the operability of the damper is improved and the compactness is achieved. We were able to plan. Further, by loosening the screw 43, the outer yoke 31 and the inner yokes 41 and 42 can be easily separated during recycling or the like.

  When the vehicle 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. After setting the target damping force of the damper 6 for each wheel based on the speed or the like, an exciting current is supplied to the MLV coil 34. Then, as shown in FIG. 6, a magnetic field is formed in the piston 16, the viscosity of the MRF flowing through the annular flow path 45 changes, and the damping force of the damper 6 increases or decreases. In the present embodiment, the thickness of the outer yoke 31 in the vicinity of the straight surface 31a is large, and the outer yoke 31 and the inner yoke 32 face each other with the tapered surfaces 31c, 41a, 42a. Magnetic saturation hardly occurs and a relatively strong magnetic field can be formed.

  When the driver stops the automobile for a long time in winter or the like, the temperature of the MRF is lowered and the viscosity is increased in the damper 6. For this reason, if damping force control is performed according to the above-described procedure immediately after traveling, the MRF is unlikely to flow through the annular flow path 45, so that the actual damping force may be greater than the target damping force. However, in this embodiment, when the temperature of the MRF is low, the valve body 52 of the temperature-sensitive cutoff valve 35 is rotated counterclockwise by the spring force of the bias spring 54 as shown in FIG. The flow path 44 is not blocked by the closing piece 52a. As a result, the MRF freely circulates between the upper liquid chamber 14 and the lower liquid chamber 15 via the bypass flow path 44 as shown by the broken arrow in FIG. The force is significantly reduced and the ride comfort is prevented from deteriorating.

  On the other hand, when the damper 6 repeatedly expands and contracts as the automobile travels, the temperature of the MRF gradually increases due to frictional heat between the cylinder 12 and the piston 16 and stirring heat associated with the movement of the piston 16. When the temperature of the MRF reaches a predetermined temperature, the temperature sensitive shut-off valve 35 contracts the shape memory spring 53 and rotates the valve body 52 counterclockwise as indicated by an arrow in FIG. As a result, the bypass flow path 44 is closed by the closing piece 52a of the valve body 52, and the MRF flows only through the annular flow path 45, so that the desired damping force control is performed.

[Second Embodiment]
FIG. 8 is an enlarged vertical cross-sectional view of a main part of a damper according to the second embodiment.
The damper of the second embodiment has the same overall configuration as that of the first embodiment described above, but the structure of the piston is slightly different. That is, as shown in FIG. 8, the piston 16 of the second embodiment includes a cylindrical outer yoke 61, a columnar inner yoke 62, and eight gap spacers 63 having a spherical shape. The outer yoke 61 is divided into two parts, a first outer yoke 64 that forms an upper part and a second outer yoke 65 that forms a lower part, and are fastened / integrated by four screws 43. Both outer yokes 64 and 65 are formed with arc-shaped grooves 64a and 65a with bottoms into which the gap spacers 33 are fitted / locked. Further, the inner yoke 62 is formed with a spherical recess 62a into which a part of the gap spacer 63 is fitted. The damper 6 of the second embodiment has substantially the same function / effect as the first embodiment described above, but the processing of the outer yoke 61 and the like are relatively easy.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the present invention is applied to a damping force variable damper that constitutes a rear suspension of a four-wheeled vehicle. However, the present invention can also be applied to a damping force variable damper for a front suspension. It can also be applied to a damping force variable damper for a two-wheeled vehicle or the like. Further, the shape, the number, the arrangement, and the like of the gap spacer are not limited to the examples in the above embodiment, and can be freely set according to the design and manufacturing requirements. In addition, the specific shape of the outer yoke and the inner yoke, the specific structure of the damper, and the like can be changed as appropriate without departing from the spirit of the present invention.

1 is a perspective view of a rear suspension according to a first embodiment. It is a longitudinal section of the damper concerning a 1st embodiment. It is the III section enlarged view in FIG. It is a bottom view of the piston concerning a 1st embodiment. It is an expansion perspective view of the piston concerning a 1st embodiment. It is a principal part longitudinal cross-sectional view of the damper which shows the effect | action of 1st Embodiment. It is a bottom view of the piston which shows the effect | action of 1st Embodiment. It is a principal part expansion longitudinal cross-sectional view of the damper which concerns on 2nd Embodiment.

Explanation of symbols

2 Trailing arm (wheel side member)
6 Damper 12 Cylinder 13 Piston rod 14 Upper liquid chamber (one side liquid chamber)
15 Lower liquid chamber (other side liquid chamber)
16 Piston 22 Damper base (vehicle body side member)
31 Outer yoke 31b Tapered surface 31c Tapered surface 32 Inner yoke 33 Gap spacer 34 MLV coil (coil)
41 First inner yoke 41a Tapered surface 42 Second inner yoke 42a Tapered surface 45 Annular flow path 61 Outer yoke 62 Inner yoke 63 Gap spacer 64 First outer yoke 65 Second outer yoke

Claims (2)

A cylinder filled with a magnetic fluid or a magnetorheological fluid and connected to one of a vehicle body side member and a wheel side member; and the cylinder is divided into a one side liquid chamber and another side liquid chamber and the magnetic fluid Alternatively, a piston formed with an annular flow path for allowing the magnetorheological fluid to flow between the one-side liquid chamber and the other-side liquid chamber and the other of the vehicle body side member and the wheel side member are connected to the piston. A damping force variable damper that has a piston rod and whose damping force is controlled by applying a magnetic field to the magnetic fluid or the magnetorheological fluid passing through the annular flow path,
The piston is
An outer yoke forming an outer peripheral side portion of the piston;
An inner yoke that is installed inside the outer yoke with a predetermined gap, and that defines the annular flow path with the outer yoke;
A coil held by the inner yoke and used for forming the magnetic field;
A gap spacer interposed between the outer yoke and the inner yoke and used for forming the gap;
One of the outer yoke and the inner yoke is divided in the axial direction so as to sandwich the other through the gap spacer, and is fastened / integrated by a fastening member.   2. The damping according to claim 1, wherein the gap formed between the outer yoke and the inner yoke is formed along a taper that increases in diameter from the substantially axial center of the piston toward both ends. Variable force damper.

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