JPH11223246A - Rotary damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent variance in damping force and a reduction in durability caused by direct contact with a plate without sacrificing requests for cost and size reductions. SOLUTION: In a rotary damper provided with a fluid room filled with viscous fluids, which is formed between a housing 2 and a rotary shaft 2 set to be mutually rotated, a plurality of housing side plates 8 and a plurality of rotary shaft side plates 3 provided alternately in an axial direction in the inner periphery of the housing 2 and the outer periphery of the rotary shaft 1 in the fluid room and arranged to oppose each other with specified clearances γ1 and γ2 between side faces of both, the specified number of ball-like particles (a) having specified diameters are mixed in the viscous fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary damper which is provided, for example, on a rotary bearing of a lower arm or an upper arm of a vehicle to attenuate the rotation of the arm.

[0002]

2. Description of the Related Art Conventionally, as a rotary damper, for example, a rotary damper described in JP-A-64-12150 is known. The rotary damper of this conventional example is provided with a housing having a fluid chamber filled with a viscous fluid therein, and in the fluid chamber of the housing, rotatable relative to the housing with respect to the housing and capable of moving by a predetermined amount in the axial direction. A plurality of rotating shafts respectively supported by the outer periphery of the rotating shaft and the inner periphery of the housing in the fluid chamber, and the sides of both rotating shafts are opposed to each other in the axial direction of the rotating shaft with a predetermined gap. Side plate and a housing-side plate, and a temperature compensation mechanism is provided between the housing and the rotating shaft-side plate to adjust the gap by axially moving the rotating shaft-side plate relative to the housing by a temperature change. Configuration.

That is, in this conventional rotary damper,
When the rotating shaft side plate and the housing side plate rotate relative to each other, the viscous fluid filled between them is forcibly moved at a flow rate according to the relative rotation speed, and the viscosity according to the viscosity of the viscous fluid at that time A frictional force is generated, and this viscous resistance becomes a damping force.

Further, when the temperature of the viscous fluid changes, the temperature compensating member adjusts the gap by moving the rotary shaft side plate, thereby automatically correcting the generated damping force fluctuation due to the temperature change of the viscous fluid. Has become.

[0005]

However, the conventional rotary damper described above has the following problems. That is, generally, the damping force (generated torque) T of a rotary damper having n pairs of opposing plates is represented by the following equation. ^{T = {π × 10 -6 ×} (d 1 4 -d 2 4) × ν × ω × n} /
(2 × 9800 × δ) where d ₁ is the effective outer shape of the shear surface, d ₂ is the effective inner diameter of the shear surface, ν is the kinematic viscosity of the viscous fluid, ω is the relative angular velocity between the plates, and δ is the gap between the plates. . As is apparent from the above equation, the larger the value of the viscous fluid kinematic viscosity v and the smaller the value of the gap δ between the opposing plates, the larger the generated damping force. In order to achieve this, it is necessary to use a viscous fluid having the highest possible viscosity and to set the gap δ between the opposing plates to a value as small as possible. However, since the gap δ between the plates is very small as described above, the two relatively rotating plates may come into direct contact with each other due to the temperature conditions and the dimensional accuracy of the plates. There is a problem in durability as a damper, such as deterioration of the viscous fluid, breakage of the plate due to contact between the two plates, and deterioration of the viscous fluid due to molecular destruction due to a rapid rise in heat generation. Further, as described above, when the gap between the plates is reduced, the generated damping force is greatly affected by the flatness of the plate, and the generated damping force becomes unstable due to the variation in the gap. In order to obtain a force, it is necessary to precisely process the flatness of each plate. However, since it is necessary to reduce the thickness of each plate as much as possible due to the demand for compactness, it is extremely difficult to precisely process and manage the flatness of each plate. By increasing the thickness of each plate, it is possible to increase the flatness of each plate and eliminate variations in the gaps. However, according to this method, the damper is increased by the amount corresponding to the increase in the plate thickness. The size in the axial direction is increased to increase the size of the mechanism and increase the cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to prevent a variation in damping force without sacrificing cost and compactness requirements. It is an object of the present invention to provide a rotary damper capable of preventing a decrease in durability due to direct contact between plates.

[0007]

According to a first aspect of the present invention, there is provided a rotary damper, wherein a fluid chamber filled with a viscous fluid is formed between a relatively rotating housing and a rotating shaft. In the fluid chamber, a plurality of housing-side plates and a plurality of rotating shaft-side plates are provided alternately in the axial direction on the inner periphery of the housing and the outer periphery of the rotating shaft, and the two sides face each other with a predetermined gap. Wherein a predetermined number of particles having a predetermined diameter are mixed in the viscous fluid. In the rotary damper according to a second aspect, in the rotary damper according to the first aspect, one or both of the housing-side plate and / or the rotating shaft-side plate are provided so as to be relatively movable in the axial direction, and the movable damper is provided. The plate is provided with a temperature compensating mechanism for adjusting the gap by relatively moving the plate in accordance with a temperature change. According to a third aspect of the present invention, in the rotary damper according to the first or second aspect, the specific gravity of the particles is substantially the same as that of the viscous fluid.

[0008]

In the rotary damper according to the first aspect of the present invention,
With the configuration described above, when the rotation shaft and the housing rotate relative to each other, the rotation shaft side plate and the housing side plate adjacent to each other rotate relative to each other in the fluid chamber filled with the viscous fluid. When the viscous fluid filled in the gap moves forcibly at a flow rate corresponding to the relative rotational speed, a viscous friction force is generated, and a predetermined damping force is generated by viscous resistance due to the viscous friction force. Since a predetermined number of particles having a predetermined diameter are mixed in the viscous fluid filled in the gap between the rotating shaft side plate and the housing side plate, the particles act as a gap holding member between the two plates. Therefore, variation in the generated damping force due to variation in the flatness of the plates is prevented, and the decrease in durability due to direct contact between the two plates is prevented. In the rotary damper according to the second aspect, the fluctuation (decrease) of the generated damping force due to the temperature change (rise) of the viscous fluid is expressed by
The correction can be made by adjusting (reducing) the gap by the temperature compensation mechanism, but the particles prevent direct contact between the two plates when the gap is reduced. In the rotary damper according to the third aspect, since the specific gravity of the particles is substantially the same as that of the viscous fluid, the particles are uniformly distributed between the two plates even after being left for a long time. Will be maintained.

[0009]

Embodiments of the present invention will be described with reference to the drawings. 1 is a cross-sectional view (cross-sectional view taken along line S1-S1 in FIGS. 2 and 3) showing a rotary damper according to an embodiment of the present invention. FIGS. 2 and 3 are lines S2-S2 and S3-S3 in FIG. It is sectional drawing in a line, As shown in these figures, the rotary damper of embodiment of this invention
The vehicle includes a rotating shaft 1 fixed to a vehicle body and an annular housing 2 connected to a bearing side on a lower arm side.

The rotating shaft 1 has small diameter portions 1a at both left and right ends.
1a and a central large-diameter portion 1b are formed in a cylindrical shape having a different outer diameter. The central large-diameter portion 1b is formed on a spline shaft 1c and has a spline hole 3a for the spline shaft 1c. Since the rotating shaft side plates 3 and the annular spacers 4 are alternately mounted, the rotating shaft 1 is maintained in a state where the plurality of rotating shaft side plates 3 are kept at predetermined intervals in the axial direction.
, And a plurality of the rotating shaft side plates 3 and the entire annular spacer 4 are integrally mounted on the rotating shaft 1 so as to be relatively movable in the axial direction.

The annular housing 2 has shaft holes 2a, 2a
The left and right side walls 2c and 2d of a disc shape having a b and a cylindrical portion 2e connecting the outer peripheral sides of the side walls 2c and 2d. Then, the shaft holes 2a, 2b of the left and right end face side walls 2c, 2d are respectively inserted into the left and right small diameter portions 1a,
1a via bearings 5 and 5, respectively, and the inner surfaces of the opening edges of the shaft holes 2a and 2b are brought into contact with the left and right end surfaces of the large-diameter portion 1b, so that the annular housing 2 rotates the rotating shaft. 1 is mounted so as to be rotatable relative to 1 and prevented from moving in the axial direction.

In the openings of the axial holes 2a, 2b of the left and right side walls 2c, 2d of the annular housing 2, the inner peripheral surfaces of the axial holes 2a, 2b and the left and right small diameter portions 1a,
1a are provided with sealing members 6 and 6, respectively, for hydraulically sealing between the outer peripheral surface of the rotating shaft 1 and the annular housing 2 by the two sealing members 6, 6. Is formed. The fluid chamber A is filled with a viscous fluid such as silicone oil in which spherical particles a having a predetermined diameter are mixed in a predetermined amount.

The outer cylindrical portion 2e is formed to have a different inner diameter with a ridge 2f formed at the center of the inner surface.
f is clamped between the left and right end side walls 2c, 2d, and the left and right opening edges of the outer peripheral cylindrical portion 2e are crimped to the outer peripheral surfaces of the left and right end side walls 2c, 2d during the assembling, respectively. , And the seal rings 2h and 2h provide a hydraulic seal between the left and right end side walls 2c and 2d.

The inner peripheral surface of the ridge 2f formed at the center of the inner surface of the outer peripheral cylindrical portion 2e is formed with a spline hole 2g, and the spline hole 2g is formed in the housing side annular spacer 7 and the spline hole 2g. The housing-side plates 8 having a spline shaft-shaped outer peripheral shape that can be engaged with each other are alternately inserted, so that the plurality of housing-side plates 8 are rotated in the rotation direction with respect to the annular housing 2 while maintaining a predetermined axial distance. And the whole of the plurality of housing-side plates 8 and the annular spacer 7 are integrally assembled with the annular housing 2 so as to be relatively movable in the axial direction.

The rotating shaft side plates 3 and the housing side plates 8 are assembled alternately, so that the plates 3 and 8 are alternately arranged in the annular housing 2 filled with the viscous fluid. As shown in detail in FIGS. 7 and 8, the side surfaces have predetermined clearances δ ₁ and δ ₂ and face each other in the axial direction. Therefore, the clearances δ ₁ and δ ₂ are filled with a viscous fluid in which spherical particles a having a predetermined diameter are mixed. The spherical particles a have a diameter (dμm) smaller than the minimum value of the clearances δ ₁ and δ ₂ (at the time of the maximum set temperature described later), and have the same specific gravity as the viscous fluid. It is composed of the material which has.

Between the inner surface of the left end side wall 2c of the annular housing 2 and the outer periphery of the housing side plate 8 and the rotary shaft side annular spacer 4 facing the outer peripheral side annular set plate 9 and the inner peripheral side annular set plate 10 A set spring 11 constituting a pressing member is interposed therebetween. This set spring 11 is shown in FIGS.
As shown in (1), the outer peripheral portion and the inner peripheral portion of the annular leaf spring material are alternately struck at four locations, thereby forming an outer peripheral spring portion 11a and an inner peripheral spring portion 11b.

Right side wall 2 of annular housing 2
On the inner surface of d, an outer peripheral side temperature compensating member 12 which comes into contact with the outer peripheral side annular set plate 15 and the inner peripheral side annular set plate 14 to receive the axial movement of the housing side plate 8 and the rotating shaft side plate 3 and an inner peripheral side. Temperature compensation member 1
3 is interposed. The outer peripheral side temperature compensating member 12 and the inner peripheral side temperature compensating member 13 are formed in a ring shape from materials having different axial linear expansion coefficients. In the embodiment of the present invention, the outer peripheral temperature compensating member 12 is formed of a material having a larger linear expansion coefficient than the inner peripheral temperature compensating member 13. The side temperature compensating member 12 is formed of a material having a higher linear expansion coefficient. Then, the inner peripheral surface of the outer peripheral side temperature compensating member 12 and the outer peripheral surface of the inner peripheral side temperature compensating member 13 face each other in the axial direction at a low temperature with a predetermined clearance L.
Is buried in the outer peripheral temperature compensating member 12 having a large linear expansion coefficient.
Engagement steps 12a and 13a are formed to move axially in the direction of the housing-side plate 8 and the rotation-axis-side plate 3 with the inner temperature compensation member 13 having a small diameter. FIG. 1 shows the positional relationship of each member at the time of the minimum set temperature.

Next, the operation of the embodiment of the present invention will be described.

First, the operation of a predetermined number of spherical particles a mixed in a viscous fluid will be described with reference to FIG. As described above, the clearances δ ₁ and δ ₂ between the rotating shaft side plate 3 and the housing side plate 8 are minutely set in order to secure a large damping force. Since the plate thicknesses of the plates 3 and 8 are also set to be thin, there is a possibility that the plates 3 and 8 that rotate relative to each other may directly contact each other depending on the temperature condition and the dimensional accuracy of the plates 3 and 8.

However, in the embodiment of the present invention, as described above, the viscous fluid filled in the clearances δ ₁ and δ ₂ between the housing-side plate 8 and the rotating shaft-side plate 3 has a predetermined diameter. Since the spherical particles a of (d μm) are mixed, the spherical particles a act as a gap holding member between the housing-side plate 8 and the rotating shaft-side plate 3, and the diameter of the spherical particles a The gap of (dμm) is kept at the minimum.

Therefore, it is possible to prevent a variation in the damping force generated due to a variation in the flatness of the plates 3 and 8, and also to prevent a direct contact between the plates 3 and 8, so that the viscosity due to the generation of wear powder is reduced. It is possible to prevent deterioration of the fluid, breakage of the plate due to contact between the two plates, and deterioration of the viscous fluid due to molecular destruction due to a rapid rise in heat generation, thereby preventing a decrease in durability.

Since the specific gravity of the spherical particles a is almost the same as that of the viscous fluid, the spherical particles a are uniformly dispersed between the plates 3 and 8 even after being left for a long time. Will be maintained.

Next, the temperature compensating operation of the temperature compensating mechanism will be described with reference to FIGS. (A) Minimum Set Temperature The rotary damper according to the embodiment of the present invention is configured as described above. Therefore, when the rotary damper is in the minimum set temperature state at the time of design (hereinafter, referred to as low temperature), FIG. As shown in FIG. 7, the clearances δ ₁ , δ ₂ between the left and right side surfaces of each rotating shaft side plate 3 and the housing side plate 8 facing each are set to be the same.

When the rotating shaft 1 and the annular housing 2 rotate relative to each other in this state, the plates 3 and 8 adjacent to each other rotate relative to each other, and the clearances δ ₁ and δ ₂ between the plates 3 and 8 When the viscous fluid filled with the fluid forcibly moves at a flow rate corresponding to the relative rotation speed, a viscous friction force is generated, and a predetermined damping force is generated by viscous resistance due to the viscous friction force.

FIGS. 10 (a) and 10 (b) show variable characteristics of the generated torque (damping force) with respect to changes in the clearances δ ₁ and δ ₂ between the plates 3 and 8.
Figure 10 solid lines clearance [delta] ₁ side of (a) generating torque T
_1, the dotted line indicates the torque T ₂ generated by the clearance [delta] ₂ side, FIG. 10 (b) shows the total torque T of both torque T _1, T _2. That is, as shown in this figure, both clearances δ ₁ , δ between both plates 3, 8
₂ has the smallest generated damping force in the same state (at a low temperature), and the generated damping force changes in a direction in which the generated damping force increases regardless of which direction the clearances δ ₁ and δ ₂ change.

(B) Intermediate set temperature At the time of the intermediate set temperature at the time of design (hereinafter referred to as normal temperature), that is, when the temperature changes from the low temperature state to the high temperature direction, the viscosity of the viscous fluid decreases. Therefore, the generated damping force changes in a direction of decreasing. That is, the generated damping force of the rotary damper changes in proportion to the viscosity of the viscous fluid as shown in the following equation (1). Damping force = (viscosity of viscous fluid × relative rotation speed × opposed area) ÷ gap ... (1) Since the viscosity of viscous fluid changes greatly depending on its temperature, the damping force also changes according to the temperature change. Therefore, the riding comfort of the vehicle fluctuates depending on the temperature.

However, in the embodiment of the present invention, the clearances δ ₁ and δ ₂ (gap) are changed by the outer peripheral temperature compensating member 12 and the inner peripheral temperature compensating member 13 so that the viscous fluid due to the temperature change is changed. It can compensate for the decrease in the generated damping force due to the decrease in viscosity.
The temperature compensating action of the two temperature compensating members 12 and 13 will be described.

When the temperature of the viscous fluid is low,
As described above, both engaging portion step portions 12a and 13 formed between the outer peripheral side temperature compensating member 12 and the inner peripheral side temperature compensating member 13.
a, a predetermined clearance L is formed between the viscous fluid and the temperature of the viscous fluid, as shown in FIG.
The outer peripheral temperature compensating member 12 and the inner peripheral temperature compensating member 13 having different linear expansion coefficients expand in the axial direction, thereby pressing and moving the housing side plate 8 and the rotating shaft side plate 3 in the axial direction (left direction in the drawing). Thereby, the clearance δ between the plates 3 and 8 is determined by the linear expansion coefficient difference.
_1, for reducing one clearance [delta] ₂ of the [delta] _2, the viscous resistance increases due to relative rotation of the plates 3,8, the damping force decreases due to the temperature rise of the viscous fluid is automatically corrected. At the time when the viscous fluid reaches the intermediate set temperature at the time of design, as shown in FIG. 8, the predetermined clearance L is lost and the two engaging steps 12a and 13a are set to engage with each other. I have.

(C) At the maximum set temperature When the viscous fluid is in the maximum set temperature state at the time of design (hereinafter referred to as high temperature), that is, when the temperature of the viscous fluid further increases from the normal temperature state, the viscous fluid Is further reduced, so that the generated damping force decreases.

However, when the viscous fluid reaches the intermediate set temperature at the time of design, the predetermined clearance L is lost and the two engaging steps 12a and 13a are engaged with each other. When the temperature of the viscous fluid further rises from the state, the outer peripheral temperature compensating member 12 having the larger linear expansion coefficient is moved along the inner peripheral temperature compensating member 13 having the smaller linear expansion coefficient in the axial direction (left direction in the drawing). to move to the axial movement amount of the low temperature-side temperature compensating member 13 is increased compared with the case where a predetermined clearance L is present, therefore, when low temperature - normal temperature reduction rate of clearance [delta] ₂ is to the temperature change Is lower than the case when the temperature changes. That is, as shown in FIG. 11, the variable characteristics of the clearances δ ₁ and δ ₂ with respect to the temperature change can be made to be non-linear characteristics in which the rate of change changes at the room temperature.

As described above, since the variable characteristics of the clearances δ ₁ and δ ₂ with respect to the temperature change can be made to be non-linear characteristics, the damping force fluctuation correction characteristics can be changed with respect to the viscous fluid which changes non-linearly with the temperature change. Viscosity (damping force) change characteristics can be approximated.

As described above, according to the rotary damper of the embodiment of the present invention, a predetermined number of spherical particles a having a predetermined diameter are mixed in the viscous fluid, so that the spherical particles a The plate 3 serves as a gap holding member between the plate 8 and the rotating shaft side plate 3.
8, it is possible to prevent the variation of the damping force generated due to the variation of the flatness of the plate 8.
8 can be prevented from lowering in durability due to the direct contact with No. 8.

When the decrease in the damping force caused by the rise in the temperature of the viscous fluid is corrected by the decrease in the clearance δ ₂ by the temperature compensating mechanism, the direct contact between the plates 3 and 8 when the clearance δ ₂ is reduced is reduced. It can be blocked by the spherical particles a.

Further, since the specific gravity of the spherical particles a is almost the same as that of the viscous fluid, the spherical particles a are uniformly dispersed between the plates 3 and 8 even after being left for a long time. Since the state can be maintained, the effect can be constantly maintained.

Further, the clearance δ ₂ for the temperature change
Can be changed to a non-linear characteristic in which the rate of change changes at room temperature, so that it is possible to obtain an effect that correction corresponding to a change in damping force based on a change in temperature becomes possible.

Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to the embodiments of the present invention, and design changes and the like may be made without departing from the scope of the present invention. The present invention is also included in the present invention.

For example, in the embodiment of the present invention, the case where the lower arm is provided on the rotation bearing portion of the vehicle is taken as an example. The present invention can be applied.

Further, in the embodiment of the present invention, an example in which the present invention is applied to a rotary damper having a temperature compensation mechanism has been described. However, the configuration of the temperature compensation mechanism is arbitrary, and no temperature compensation mechanism is provided. The present invention can be applied to a rotary damper.

[0039]

As described above, in the rotary damper according to the first aspect of the present invention, as described above, the fluid chamber filled with the viscous fluid between the relatively rotating housing and the rotating shaft is provided. A plurality of housing side plates and a plurality of rotation plates are formed in the fluid chamber and are provided alternately in the axial direction on the inner circumference of the housing and the outer circumference of the rotating shaft, and the two sides face each other with a predetermined gap therebetween. A shaft-side plate, and a means in which a predetermined number of particles of a predetermined diameter are mixed in the viscous fluid, so that the particles act as a gap holding member between the housing-side plate and the rotating shaft-side plate. In addition, it is possible to prevent the variation in the damping force generated due to the variation in the flatness of the plates, and to prevent the durability from being reduced by the direct contact between the two plates. Effect that way made is obtained. In the rotary damper according to the second aspect, in the rotary damper according to the first aspect, one or both of the housing-side plate and / or the rotating shaft-side plate are provided so as to be relatively movable in the axial direction, and the movable body is provided. The plate is provided with a temperature compensating mechanism that adjusts the gap by relatively moving the plate according to a temperature change, so that the fluctuation (decrease) of the generated damping force due to the temperature change (rise) of the viscous fluid is reduced. When correction is made by adjusting (reducing) the gap by the temperature compensation mechanism, the particles can prevent direct contact between the two plates when the gap is reduced. In the rotary damper according to the third aspect, in the rotary damper according to the first or second aspect, the specific gravity of the particles is substantially the same as that of the viscous fluid. Since it is possible to maintain a state in which the particles are uniformly dispersed and arranged between the two plates, the above-described effect can be constantly maintained.

[Brief description of the drawings]

FIG. 1 is an overall sectional view showing a state of a rotary damper according to an embodiment of the present invention at a low temperature (S1-S in FIGS. 2 and 3);
FIG.

FIG. 2 is a sectional view taken along line S2-S2 in FIG.

FIG. 3 is a sectional view taken along line S3-S3 in FIG.

FIG. 4 is a plan view showing a set spring.

FIG. 5 is a sectional view taken along line S5-S5 in FIG. 4;

FIG. 6 is an enlarged cross-sectional view of a main part for explaining a spacing effect by spherical particles.

FIG. 7 is an enlarged sectional view of a main part showing details of a temperature compensating member at a low temperature.

FIG. 8 is an enlarged sectional view of a main part showing details of a temperature compensating member at a normal temperature.

FIG. 9 is an enlarged sectional view of a main part showing details of a temperature compensating member at a high temperature.

FIG. 10 is a variable characteristic diagram of generated torque (damping force) with respect to both clearance changes between the rotation shaft side plate and the annular housing side plate.

FIG. 11 is a diagram showing a viscosity change characteristic and a clearance variable characteristic of a viscous fluid with respect to a temperature change.

[Explanation of symbols]

 Reference Signs List A fluid chamber a spherical particle 1 rotating shaft 2 annular housing 3 rotating shaft side plate 8 housing side plate 12 outer temperature compensation member (temperature compensation mechanism) 13 inner temperature compensation member (temperature compensation mechanism)

Claims (3)

[Claims] A fluid chamber filled with a viscous fluid is formed between a relatively rotating housing and a rotating shaft. In the fluid chamber, an inner periphery of the housing and an outer periphery of the rotating shaft are alternately provided in the axial direction. A plurality of housing-side plates and a rotating shaft-side plate that face each other with a predetermined gap therebetween, and that a predetermined number of particles having a predetermined diameter are mixed in the viscous fluid. A characteristic rotary damper. 2. One or both of the housing-side plate and / or the rotating shaft-side plate are provided so as to be relatively movable in the axial direction, and the movable plate is relatively moved by a temperature change. The rotary damper according to claim 1, further comprising a temperature compensating mechanism that adjusts the gap by using a temperature compensation mechanism. 3. The rotary damper according to claim 1, wherein the specific gravity of the particles is substantially the same as that of the viscous fluid.