JP2008309239A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber capable of restraining a change in damping force caused by a temperature change in a hydraulic fluid. <P>SOLUTION: This hydraulic shock absorber has a valve disc 2 defining the inside of a cylinder sealed with the hydraulic fluid, a port 6a communicating mutual oil chambers 3 and 4 defined by the valve disc 2, and a leaf valve 13 arranged by blocking up the port 6a and opening by deflecting when a pressure difference between the oil chambers 3 and 4 exceeds a predetermined value. The valve disc 2 has a support part 23 supporting the leaf valve 13, and a seat part 24 having a seat surface 24a for seating the leaf valve 13 and sealing a space with the leaf valve 13. A coefficient of linear expansion of the seat part 24 is set larger than a coefficient of linear expansion of the support part 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hydraulic shock absorber.

As a hydraulic shock absorber mounted on a vehicle such as an automobile, a piston that defines a cylinder with two oil chambers, a port that is provided in the piston and that communicates with the two oil chambers, and a port that can be opened and closed are provided. The thing provided with the open leaf valve is known (for example, refer to patent documents 1).
JP 2004-190716 A

  In this type of hydraulic shock absorber, when the temperature of the hydraulic oil increases, the viscosity of the hydraulic oil decreases and the generated damping force tends to decrease. Further, when the temperature of the hydraulic oil decreases, the viscosity of the hydraulic oil increases and the generated damping force tends to increase.

  As described above, when the temperature of the hydraulic oil changes, the viscosity of the hydraulic oil changes accordingly, so that the damping force generated by the hydraulic shock absorber changes. Therefore, a desired damping force characteristic may not be obtained depending on the temperature change.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic shock absorber that can suppress a change in damping force accompanying a change in temperature of hydraulic oil.

  The present invention provides a valve disk defining a cylinder filled with hydraulic oil, a port formed in the valve disk and communicating between oil chambers defined by the valve disk, and closing the port. And a leaf valve that bends and opens when the pressure difference between the upstream oil chamber and the downstream oil chamber exceeds a predetermined value. A support portion that supports the leaf valve; and a seat portion that has a seat surface on which the leaf valve is seated and seals between the leaf valve, and the linear expansion coefficient of the seat portion is linearly expanded. It is characterized by being larger than the rate.

  According to the present invention, since the linear expansion coefficient of the seat part is larger than the linear expansion coefficient of the support part, when the temperature of the hydraulic oil is high, the sheet part linearly expands compared to the support part, The crimping force with the leaf valve increases. Thereby, the generated damping force is increased, and the decrease in the damping force due to the decrease in the viscosity of the hydraulic oil is compensated. Further, when the temperature of the hydraulic oil is low, the linear expansion of the seat portion is suppressed, so that the pressure-bonding force between the seat portion and the leaf valve becomes small. Thereby, the generated damping force is reduced, and an increase in the damping force due to an increase in the viscosity of the hydraulic oil is suppressed. Thus, the change of the damping force accompanying the temperature change of hydraulic fluid can be suppressed by the difference in the linear expansion coefficient between the seat part and the support part.

  Embodiments of the present invention will be described below with reference to the drawings.

  With reference to FIG.1 and FIG.2, the hydraulic shock absorber 100 which concerns on embodiment of this invention is demonstrated. 1 is a cross-sectional view of the hydraulic shock absorber 100, and FIG. 2 is a partially enlarged view of a region A in FIG.

  First, the overall configuration of the hydraulic shock absorber 100 will be described with reference to FIG.

  The hydraulic shock absorber 100 is interposed between a vehicle body and an axle in a vehicle such as an automobile, and has a function of suppressing a change in vehicle body posture.

  The hydraulic shock absorber 100 includes a cylindrical cylinder 1 in which hydraulic oil is sealed, a piston 2 that is slidably inserted into the cylinder 1 and defines the two oil chambers 3 and 4 in the cylinder 1, and one end. The piston 2 is fixed, and the other end includes a rod 5 extending to the outside of the cylinder 1. In the present embodiment, the piston 2 corresponds to the valve disk.

  A gas chamber (not shown) is provided in the cylinder 1 to compensate for volume changes in the cylinder 1 due to the entry and exit of the rod 5.

  The piston 2 has a cylindrical core portion 2a through which the rod 5 is inserted, and an annular ring portion 2b that slides with the inner periphery of the cylinder 1 via a band 8 attached to the outer periphery. The ring portion 2b is formed to have a larger axial dimension than the core portion 2a. As a result, the piston 2 is formed with an accommodating portion 2c surrounded by the ring portion 2b.

  The piston 2 is formed with a plurality of inner peripheral ports 6 a that always communicate with the rod-side oil chamber 3 and a plurality of outer peripheral ports 6 b that always communicate with the oil chamber 4 on the opposite rod side. The hydraulic oil in the cylinder 1 moves back and forth between the oil chamber 3 and the oil chamber 4 via the inner peripheral port 6a and the outer peripheral port 6b. Specifically, the inner peripheral port 6 a is a flow path that guides hydraulic oil in the oil chamber 3 to the oil chamber 4 when the hydraulic shock absorber 100 is extended, and the outer peripheral port 6 b is when the hydraulic shock absorber 100 is compressed. This is a flow path for guiding the hydraulic oil in the oil chamber 4 to the oil chamber 3.

  An annular groove 2d in which hydraulic oil flowing out from the plurality of inner peripheral ports 6a joins is formed at the outlet of the inner peripheral port 6a in the piston 2, and a plurality of outer peripheral ports 6b are formed at the outlet of the outer peripheral port 6b. An annular groove 2e is formed in which the hydraulic oil that has flowed out of the tank joins.

  The band 8 is made of resin, and the piston 2 slides along the inner periphery of the cylinder 1 via the band 8, so that wear of the inner periphery of the cylinder 1 is suppressed, and the inner periphery of the cylinder 1 and the outer periphery of the piston 2 are The passage of hydraulic oil between the two is prevented and good sealing performance is obtained.

  The rod 5 has a rod main body portion 5a that slides relative to the cylinder 1 via a bearing (not shown), and an inlay portion 5b that is formed on the distal end side and has a smaller diameter than the rod main body portion 5a. Each member including the piston 2 is assembled to the inlay portion 5b.

  The member assembled | attached to the inlay part 5b is demonstrated.

  A step portion 5c is formed at the boundary between the rod main body portion 5a and the spigot portion 5b in the rod 5, and an annular valve stopper 10 is locked to the step portion 5c. The valve stopper 10 is formed with a plurality of through holes 10a through which hydraulic oil passes.

  The valve stopper 10 is disposed in contact with the inner peripheral side of the laminated leaf valve 12 via a spacer 11, and the piston 2 is disposed in contact with the laminated leaf valve 12. Thus, the laminated leaf valve 12 is disposed between the valve stopper 10 and the piston 2 so that the inner peripheral side thereof is supported and the annular groove 2e which is the outlet portion of the outer peripheral port 6b is closed.

  A laminated leaf valve 13 is accommodated in the accommodating portion 2c of the piston 2 in contact with the core portion 2a. On the inner peripheral side of the laminated leaf valve 13, a male screw portion 5d at the tip of the inlay portion 5b is screwed through a spacer 14. The mating nuts 15 are arranged in contact with each other. As described above, the laminated leaf valve 13 is supported between the piston 2 and the nut 15 on the inner peripheral side thereof, and is disposed so as to close the annular groove 2d that is the outlet portion of the inner peripheral port 6a.

  As described above, the valve stopper 10, the spacer 11, the laminated leaf valve 12, the piston 2, the laminated leaf valve 13, the spacer 14, and the nut 15 are sequentially inserted into the inlay part 5 b, and each of these members is inserted. Is fixed to the spigot part 5 b by tightening the nut 15.

  The laminated leaf valves 12 and 13 are configured by laminating a plurality of annular leaf valves, and bend and open when the pressure difference between the upstream oil chamber and the downstream oil chamber exceeds a predetermined value. It is. In the present embodiment, the laminated leaf valves 12 and 13 are described as being formed by laminating a plurality of leaf valves. However, the number of leaf valves to be laminated is determined by the required damping force, and the leaf valves are determined. It is also possible to configure with only one leaf valve without stacking.

  The laminated leaf valve 12 is arranged such that the inner peripheral side is supported by the support portion 21 of the piston 2 and the outer peripheral side is seated on the seat portions 22a and 22b of the piston 2 and the outer peripheral port 6b is closed. Therefore, when the hydraulic shock absorber 100 is compressed and the pressure in the oil chamber 4 rises and the pressure difference between the oil chamber 3 and the oil chamber 4 exceeds a predetermined value, the outer peripheral side bends and opens. Thereby, a gap is generated between the laminated leaf valve 12 and the seat portions 22a and 22b, and a damping force is generated by the flow resistance generated when the hydraulic oil passes through the gap. Thus, the laminated leaf valve 12 is a damping valve for the compression stroke.

  Similarly, the laminated leaf valve 13 is also arranged so that the inner peripheral side is supported by the support portion 23 of the piston 2 and the outer peripheral side is seated on the seat portion 24 of the piston 2 and the inner peripheral port 6a is closed. Therefore, when the hydraulic shock absorber 100 is extended, the pressure in the oil chamber 3 rises and the pressure difference between the oil chamber 3 and the oil chamber 4 exceeds a predetermined value, the outer peripheral side bends and opens. Thus, the laminated leaf valve 13 is a damping valve for the extension stroke. The laminated leaf valve 12 is formed with a through passage 16 for guiding hydraulic oil to the inner peripheral port 6a, and the inlet passage of the inner peripheral port 6a is connected to the through passage 16 and the inner peripheral port 6a. An annular groove 2 f is formed, and the inner peripheral port 6 a is always in communication with the oil chamber 3 through the annular groove 2 f and the through passage 16.

  As described above, the laminated leaf valves 12 and 13 are supported by the support portions 21 and 23 on the inner peripheral side of the piston 2 and are disposed and supported on the seat portions 22 and 24 on the outer peripheral side of the piston 2. The free end side, which is the outer peripheral side, is bent and opened with the base end side (anti-free end side) supported by the parts 21 and 23 as a fulcrum.

  Next, mainly with reference to FIG. 2, the support portions 21 and 23 and the seat portions 22 and 24 in the piston 2 will be described in detail. In the following description, the support portion 23 and the seat portion 24 that are in contact with the laminated leaf valve 13 for the extension stroke will be described as an example.

  As described above, the piston 2 has the support surface 23a that is in surface contact with the laminated leaf valve 13 and the support portion 23 that supports the laminated leaf valve 13, and the seat surface 24a on which the laminated leaf valve 13 is seated. And a seat portion 24 that seals between the valve 13.

  The support surface 23a of the support portion 23 is set to have a slightly lower height in the axial direction of the rod 5 than the seat surface 24a of the seat portion 24 at a predetermined reference temperature, and the support surface 23a and the seat surface 24a The initial load of the laminated leaf valve 13 is set by the step.

  The seat part 24 is an annular ring member whose seat surface 24a is in contact with the free end side of the leaf valve 13a over the entire circumference, and is press-fitted into the outer periphery of the core part 2a.

  As described above, the seat portion 24 is configured separately from the piston 2 including the support portion 23, and the material of the seat portion 24 is configured of a material different from the material of the piston 2. That is, the sheet part 24 and the support part 23 are made of different materials.

  The sheet portion 24 is made of a material having a larger linear expansion coefficient than the support portion 23. In the ring shape of the seat portion 24, the ring width (dimension L in FIG. 2), which is the dimension in the axial direction of the rod 5, is longer than the ring thickness. Therefore, the seat portion 24 has a large amount of expansion in the axial direction of the rod 5 due to temperature rise. That is, the dimension L of the sheet portion 24 increases due to the temperature rise.

  From this, when the temperature of the hydraulic oil rises above the reference temperature, the seat portion 24 expands in the axial direction of the rod 5, and the amount of expansion is larger than that of the support portion 23.

  As a result, the laminated leaf valve 13 is in a state in which the base end side is supported and the free end side is pressed by the seat portion 24, so that the pressure bonding force between the seat surface 24a and the leaf valve 13a is increased.

  By increasing the pressure-bonding force between the seat surface 24a and the leaf valve 13a, it becomes difficult for hydraulic oil to pass between the seat portion 24 and the leaf valve 13a.

  In this way, when the temperature of the hydraulic oil rises above the reference temperature, the damping force generated tends to decrease because the viscosity of the hydraulic oil decreases, but the seat portion 24 expands as the temperature rises, and the leaf It acts so that it becomes difficult for hydraulic oil to pass between the valves 13a. Therefore, a decrease in the damping force due to a decrease in the viscosity of the hydraulic oil is compensated by the expansion of the seat portion 24.

  Further, when the temperature of the hydraulic oil is lower than the reference temperature, the seat portion 24 contracts in the axial direction of the rod 5, and the contraction amount is larger than that of the support portion 23.

  Thereby, the pressure-bonding force between the seat surface 24a and the leaf valve 13a is reduced, and the hydraulic oil easily passes between the seat portion 24 and the leaf valve 13a.

  As described above, when the temperature of the hydraulic oil decreases, the damping force generated tends to increase because the viscosity of the hydraulic oil increases. However, the seat portion 24 contracts due to the temperature decrease, and the leaf valve 13a is in contact with the leaf valve 13a. It acts so that the hydraulic oil can easily pass between them. Therefore, an increase in damping force due to an increase in the viscosity of the hydraulic oil is suppressed by contraction of the seat portion 24.

  As described above, the sheet portion 24 expands and contracts relative to the support portion 23 due to a temperature change, and acts to compensate for a temperature change of the damping force accompanying the temperature change.

Next, another aspect of the present embodiment will be described.
(1) In the above description, the laminated leaf valve 13 for the extension stroke has been described as an example, but the present invention may naturally be applied to the support portion 21 and the seat portion 22 that are in contact with the laminated leaf valve 12 for the compression stroke. Is possible.

(2) Further, the damping force during the compression stroke of the hydraulic shock absorber 100 is not a laminated leaf valve 12 but a leaf valve arranged on a base valve (not shown) arranged fixed to the bottom of the cylinder 1. In the case of generation, the present invention can be applied to the base valve. In this case, the base valve corresponds to the valve disc.

(3) In the above description, the seat portion 24 is configured separately from the piston 2 including the support portion 23, and the material thereof is configured of a material different from the material of the piston 2. Instead, as shown in FIG. 3, the support portion 23 is configured separately from the piston 2 including the seat portion 24, and the material is configured of a material different from the material of the piston 2. May be.

  Specifically, the support portion 23 is an annular ring member that contacts the opposite free end side of the leaf valve 13a over the entire circumference, and is made of a material having a smaller linear expansion coefficient than the seat portion 24. The

  Thus, also in this aspect, the sheet portion 24 is made of a material having a larger linear expansion coefficient than the support portion 23. Therefore, when the temperature of the hydraulic oil rises, the amount of expansion of the seat portion 24 is larger than that of the support portion 23, so that the free end side of the laminated leaf valve 13 is pressed by the seat portion 24, and the seat surface The pressure bonding force between 24a and the leaf valve 13a is increased. Further, when the temperature of the hydraulic oil is lowered, the contraction amount of the seat portion 24 is larger than that of the support portion 23, and therefore the pressure-bonding force between the seat surface 24a and the leaf valve 13a is reduced.

  Thus, even if the support portion 23 is made of a material having a smaller linear expansion coefficient than the sheet portion 24, the sheet portion 24 expands and contracts relative to the support portion 23 due to a temperature change, and the temperature change It acts to compensate the temperature of the change in damping force accompanying the.

(4) Further, both the support portion 23 and the seat portion 24 are ring members separate from the piston 2, and the linear expansion coefficient of the seat portion 24 is configured to be larger than the linear expansion coefficient of the support portion 23. May be.

(5) When the seat portion 24 is configured separately from the piston 2 including the support portion 23, the seat portion 24 may be configured of a shape memory alloy. In this case, when the temperature of the seat portion 24 is lower than the reference temperature (transformation point), the seat portion 24 is compressed and deformed by the urging force in the valve closing direction of the laminated leaf valve 13, and when the temperature rises above the reference temperature, the seat portion 24 expands and recovers its original shape. Set to do. As the temperature of the hydraulic oil rises and the seat portion 24 recovers to its original shape, the pressure-bonding force between the seat surface 24a and the leaf valve 13a increases. Thus, even if the seat portion 24 is formed of a shape memory alloy, the seat portion 24 expands and contracts relative to the support portion 23 due to a temperature change, and compensates for a change in damping force accompanying the temperature change. Acts as follows.

  According to the above embodiment, the following operational effects are obtained.

  Since the linear expansion coefficient of the seat part 24 is larger than the linear expansion coefficient of the support part 23, when the temperature of the hydraulic oil is high, the sheet part 24 linearly expands compared to the support part 23, and the sheet part 24 and the leaf The pressure-bonding force with the valve 13a is increased. Thereby, the generated damping force is increased, and the decrease in the damping force due to the decrease in the viscosity of the hydraulic oil is compensated. Further, when the temperature of the hydraulic oil is low, the linear expansion of the seat portion 24 is suppressed, so that the pressure-bonding force between the seat portion 24 and the leaf valve 13a becomes small. Thereby, the generated damping force is reduced, and an increase in the damping force due to an increase in the viscosity of the hydraulic oil is suppressed.

  As described above, a difference in linear expansion coefficient between the seat portion 24 and the support portion 23 causes a step between the seat portion 24 and the support portion 23, so that the pressure-bonding force between the seat portion 24 and the leaf valve 13a changes. Thereby, the change of the damping force accompanying the temperature change of hydraulic fluid is suppressed, and even when the temperature change of hydraulic fluid is large, a desired damping force characteristic can be obtained.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The present invention can be applied to a shock absorber mounted on a vehicle.

It is sectional drawing which shows the hydraulic shock absorber 100 in embodiment of this invention. It is the elements on larger scale of the area | region A in FIG. It is a figure which shows the other aspect of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hydraulic buffer 1 Cylinder 2 Piston 3, 4 Oil chamber 5 Rod 6a Inner peripheral port 6b Outer peripheral port 12, 13 Laminated leaf valve 13a Leaf valve 21, 23 Support part 22a, 22b, 24 Seat part 23a Support surface 24a Seat surface

Claims (4)

A valve disk defining a cylinder filled with hydraulic oil;
A port formed in the valve disc and communicating between oil chambers defined by the valve disc;
A leaf valve that is arranged with the port closed and a leaf valve that bends and opens when the pressure difference between the upstream oil chamber and the downstream oil chamber exceeds a predetermined value,
The valve disc is
A support for supporting the leaf valve;
A seat portion on which the leaf valve is seated, and a seat portion that seals between the leaf valve, and
The hydraulic shock absorber according to claim 1, wherein a linear expansion coefficient of the seat portion is larger than a linear expansion coefficient of the support portion.   2. The hydraulic shock absorber according to claim 1, wherein the seat portion is a ring member in which the seat surface is in contact with the free end side of the leaf valve over the entire circumference.   3. The hydraulic shock absorber according to claim 2, wherein the seat portion is formed of a shape memory alloy that is compressed and deformed by an urging force of the leaf valve and that expands and recovers to its original shape when the temperature rises above a reference temperature. vessel.   3. The hydraulic shock absorber according to claim 1, wherein the support portion is a ring member that abuts against the non-free end side of the leaf valve over the entire circumference.

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