JPH0289830A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To improve rise characteristics in a low speed area by a method wherein a disc valve is formed in structure having no constant orifice opened in a lower speed area. CONSTITUTION:When a piston 5 is slid, a hydraulic difference is produced in either of spaces between upper and lower liquid chambers 1a, 1b and a reservoir chamber 7. A disc valve 5d at a first stage having no constant orifice is opened and the flow of working liquid is produced through the communicating passage of the piston 5 or a base 4, and a damping force is generated. In this case, when the slide speed of a piston 5 is in a low speed area, the disc valve 5d having no constant orifice is opened, and compared with a disc valve having a constant orifice, a damping force is generated with an excellent rise.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improving the damping force characteristics of a hydraulic shock absorber.

(Prior art) As a conventional hydraulic shock absorber, for example,
The one described in No. 035 is known.

This hydraulic shock absorber includes a cylinder tube whose interior is partitioned into an upper liquid chamber and a lower liquid chamber by a piston provided at the lower end of a piston rod, and a base which partitions the lower liquid chamber and reservoir chamber of the cylinder tube. and a guide member provided at the end of the cylinder tube to guide the piston rod as it enters and exits the cylinder tube.
The piston was equipped with a disc valve that opened to generate a damping force on the piston.

The disc valve is provided to open and close an orifice hole drilled in the piston body, and a constant orifice is provided between the disc valve and the seat surface to allow hydraulic fluid to flow in a low speed range. It had a structure.

In a hydraulic shock absorber with such a structure, the damping force of the disc valve has the characteristics shown in Fig. 12 (a).In other words, in the low speed range, the constant orifice increases the damping force to the square of the speed. When the disc valve opens, the speed becomes a 2/3 power characteristic. In addition, the damping force of the orifice hole is as shown in Fig. 12 (b).
The power property is obtained.

Therefore, the damping force of this hydraulic shock absorber is shown in Figure 12 (
b) Characteristics as shown in Figure 13 combining the characteristics of 4 mouths),
That is, a characteristic is obtained in which the rise in the low speed range is gradual, the slope becomes steeper as the speed reaches the middle speed range, and the slope becomes flat at the subsequent inflection point.

(Problem to be Solved by the Invention) However, in the conventional hydraulic shock absorber having the damping force characteristics as described above, the damping force in the low speed range is low, so low frequency vehicle body vibration is For example, there is a problem in that the steering stability is poor when turning the steering wheel or when driving at high speed.

Therefore, in order to increase the damping force in the low speed range, it is possible to avoid providing a constant orifice in a disc valve that opens in the low speed range, and to obtain speed characteristics from the low speed range to the 2/3 power. (For example, German patent 833
No. 574).

However, if the constant orifice is simply abolished, a small amount of hydraulic fluid will leak between the piston and the cylinder tube or between the piston rod and the guide member, and these leaks will be ,
A new problem occurred in that the damping force acted as if a constant orifice was provided, and the rise of the damping force during operation was slow. Incidentally, in the case of a device having a constant orifice, such leakage did not pose a problem because the same characteristics as the constant orifice were obtained.

The present invention was made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a hydraulic shock absorber that has excellent damping force rise characteristics in a low speed range.

(Means for Solving the Problem) In order to achieve such an object, in the hydraulic shock absorber of the present invention, one end is sealed by a guide member, and the other end is sealed from the reservoir chamber by a base. The stopped cylinder tube, the piston provided at the tip of the piston rod guided by the guide member and dividing the inside of the cylinder into an upper liquid chamber and a lower liquid chamber, and the upper liquid chamber and the lower liquid chamber are communicated with each other. A damping force is provided in at least one of the communication passage formed in the piston and the communication passage formed in the base to communicate the lower liquid chamber and the reservoir chamber, and the damping force is applied when the hydraulic fluid flows through the communication passage. a disc valve that opens in order to generate the fluid, and the disc valve is formed in a structure that does not have a constant orifice that opens in a low speed range, and the disc valve has a structure that does not have a constant orifice that opens in a low speed range, and a fluid chamber is provided between the piston and the cylinder tube on the outer periphery of the piston. The guide member is provided with a seamless seal ring that seals the upper liquid chamber and the outside of the cylinder tube.

Further, the seal ring is in close contact with the piston rod, has a distance from the guide member that can follow the eccentricity of the piston rod, and has a position regulating member provided on the guide member that allows the piston to move. #f4 path may be used in which the axial movement of the rod is restricted.

(Function) In the hydraulic shock absorber of the present invention, when the piston slides, a hydraulic pressure difference occurs between the upper liquid chamber, the lower liquid chamber, and the reservoir chamber, and the disc valve that does not have a constant orifice opens, causing the piston to slide. Alternatively, the hydraulic fluid flows through the communication path in the base, and damping force is generated.

At this time, if the sliding speed of the piston is in a low speed range, a disc valve without a constant orifice is opened, and compared to a disc valve with a constant orifice,
Damping force is generated with good start-up.

Also, at this time, the distance between the piston outer circumference and the cylinder tube is 1! Since it is sealed with a seamless piston ring, there will be no leakage in this area, and since there is also a seamless seal ring between the piston rod outer periphery and the guide member, there will be no leakage in this area. It never occurs.

Therefore, if a leak occurs at such a location,
As if there were a constant orifice, there would be no delay in startup.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing a hydraulic shock absorber according to a first embodiment of the present invention, and numeral 1 in the figure indicates a cylinder tube. This cylinder tube 1 has an upper end closed by a guide member 2 and a seal member 3, a lower end closed by a base 4, and is filled with hydraulic fluid, and inside this cylinder tube 1, A piston 5 is slidably loaded,
It is divided into an upper liquid chamber la and a lower liquid chamber 1b.

Further, a bottomed cylindrical outer cylinder 6 is provided on the outside of the cylinder tube 1, and a liquid chamber 1a inside the cylinder tube 1,
A reservoir chamber 7 is defined by the guide member 2 and the base 4 with respect to the reservoir chamber 7 and filled with a desired amount of working fluid under the pressure of the enclosed gas.

The piston 5 is attached to the lower end of the piston rod 8. That is, the lower end of the piston rod 8 has a mounting portion 8b having a smaller diameter than the upper portion and having a thread 8a formed on the outer periphery.
are provided, and a retainer 5a,
Check plate 5b, piston body 5c, first stage disc valve 5d, washer 5e, stopper plate 5f, second stage disc valve 5g, washer 511.
The assist spring 5m is sequentially inserted into the collar 5j and the spring seat 5, and finally fastened with a tightening nut 5n.

To explain further, the piston body 5c is provided with a large-diameter mounting hole 501 in the axial direction in the center thereof, and
A first communicating path 502 with a large cross-sectional area and a second communicating path 503 with a small cross-sectional area are formed at the outer side thereof.

The first communicating path 502 is connected to the check plate 5.
b closes the opening at the upper end, and is formed to allow only the flow of the working fluid from the lower fluid chamber 1b to the upper fluid chamber 1c.

On the other hand, as shown in Fig. 2, which is a detailed view of part A in Fig. 1,
On the lower surface side of the piston body 5C, a boss seat surface 504 is formed closer to the center than the second communication path 503, and a first seat surface 505 is formed on the outside of the second communication path 503, and further, A second sheet surface 506 is formed on the outside thereof.

Note that this second seat surface 506 is formed with a step at a lower position than the first seat surface 505, and between both seat surfaces 506 and 506.

A ring 507 is formed which is annular and has a semicircular cross section.

The boss portion seat surface 504 and the first seat surface 50
The first stage disc valve 5d is brought into contact with the first stage disc valve 5d, and the second communication passage 503 can be opened and closed by this first stage disc valve 5d.

Note that this first stage disc valve 5d is
The outer periphery of the washer 5e, which has a smaller diameter, provides a support point for bending, and when the washer 5e bends by the thickness thereof, it comes into contact with the stopper plate 5f, changing the valve opening force.

Furthermore, a second stage disc valve 5g is brought into contact with the second seat surface 506, being urged by an assist spring 5m. A constant orifice 508 is formed in the piston body 5c at the second seat surface 506 position, which communicates the inside and outside of the contact surface between the second stage disc valve 5g and the second seat surface 506.

The first-stage disc valve 5d is elastically formed to open even when the piston speed is extremely low, and this is made possible by the two-stage valve structure.

Next, the base 4 is also provided with a valve structure,
Its structure will be explained.

As shown in FIG. 1, the base 4 includes a port 4a, a washer 4b, a second stage disc valve 4c, a washer 4d, a first stage disc valve 4e, and a base body 4f.
, check plate 4g.

The retainer 4h and collar 4j are sequentially inserted and finally fastened with a tightening nut 4k.

In addition, the base body 4f has a through hole 401 formed in the center thereof through which the bolt 4a is passed, and a first communicating passage 402 with a large cross-sectional area and a second communicating passage 403 with a small cross-sectional area. .

Then, a check plate 4 is placed on the top surface of the base body 4f.
By making contact with g, the first communication path 402 allows only the flow of the working fluid from the reservoir chamber 7 to the lower liquid chamber 1b.

Furthermore, FIG. 3 is a detailed view of part B in FIG. 1 showing the main parts of the base 4, and the lower end surface of the base 4.

The second communicating path 403 has a boss on the center side of the pace.
04 is formed, a first seat surface 405 is formed outside the second communication path 403, and a second seat surface 406 is further formed outside of the first seat surface 405.

Note that this second seat surface 406 is formed with a step at a lower position than the first seat surface 405, and between the two seat surfaces 405 and 406.

A ring 407 is formed which is annular and has a semicircular cross section. Moreover, in several places on this second sheet surface 406,
A constant orifice 40B is formed.

The boss side seat surface 404 and the first seat surface 40
The first stage disc valve 4e is brought into contact with the first stage disc valve 4e, and the second communication passage 403 can be opened and closed by the first stage disc valve 4e.

Note that this first stage disc valve 4e is
A support point for bending is provided by the outer circumference of the washer plate 4d, which has a smaller diameter than the washer plate 4d, and when the washer plate 4d bends by the thickness, it comes into contact with the second stage disc valve 4c, and the valve opening force changes. It has become.

Further, a second stage disc valve is in contact with the second seat surface.

Next, the upper end of the hydraulic shock absorber according to the embodiment will be explained with reference to FIG.
a is formed. Further, a guide bush 9 is provided on the inner periphery of this through hole 2a.

The seal member 3 provided on the upper side of the guide member 2 is provided with a lip 3a that contacts and seals the piston rod 8, and a through hole 9 is provided between the seal member 3 and the guide member 2. A liquid reservoir chamber 10 is provided for storing the hydraulic fluid leaked from between the piston rod 8 and the piston rod 8, and the liquid reservoir chamber 10 is communicated with the reservoir chamber 7 through a communication groove 20 formed in the guide member 2. ing.

Moreover, the lip 3a of the seal member 3 is in contact with the piston rod 8 and seals between the liquid reservoir chamber 10 and the outside, a seal portion 3b, and between the liquid reservoir chamber 10 and the communication groove 2c.
A check portion 3c is formed that allows only the flow of the working fluid from the liquid storage chamber 10 to the reservoir chamber 7, and restricts the flow of the sealed gas and the working fluid in the reservoir chamber 7 in the opposite direction.

As described above, the upper liquid chamber 1a and the lower liquid chamber 1b are partitioned by the piston 5, the lower liquid chamber 1b and the reservoir chamber 7 are partitioned by the base 4, and the reservoir chamber 7 and the upper liquid chamber 1 are partitioned by the base 4.
a refers to the guide member 2 and the lip 3a of the seal member 3.
However, in this embodiment, in order to improve the sealing performance between each chamber 1a, Ib, 7, a piston ring 11 is provided on the outer periphery of the piston body 5c, and a guide member 2 and A seal ring 12 is provided between the piston rod 8 and the piston rod 8 .

The piston ring II is made of polychloro trifluoro.
A fitting groove formed on the outer periphery of the piston body 5C, as shown in Fig. 4, which is a detailed view of the C part in Fig. The piston body 5c is provided in a fitted state in which the movement in the sliding direction of the piston body 5c is restricted, and the protrusion 5q formed at the center of this fitting groove 5p allows the outer periphery of the upper end to be fixed as shown in the figure. is in contact with the inner surface of the cylinder tube l, and the inner periphery of the lower end is in contact with the piston body 5C side to obtain sealing properties.

Polychlorotrifluoroethylene, which is the material of the piston ring 11, has high lubricity, low sliding resistance, and excellent operability.

Further, the seal ring 12 is connected to the piston ring 1.
1, it is formed of polychlorotrifluoroethylene into a ring shape with no seam in the middle, and the inner periphery is in contact with the piston rod 8. As shown in FIG. 5, which is a detailed view of section D in FIG. The piston rod 8 is housed in the housing groove 13a formed by the tightly fitted cover 13, and the forward and backward movement of the piston rod 8 is restricted. By making it large, a moving allowance 13b that can follow the eccentricity of the piston rod 8 is provided.

Next, the operation of the embodiment will be explained.

(1) During the extension stroke, when the piston 5 slides in the extension direction (in the direction of narrowing the upper liquid chamber 1a), the liquid is moved through the second communication passage 503 of the piston 5 based on the difference in liquid pressure between the upper and lower liquid chambers 1a and Ib. upper liquid chamber 1a
The hydraulic fluid flows from the reservoir chamber 1b to the lower fluid chamber 1b, and an amount of hydraulic fluid corresponding to the volume of the piston rod 8 withdrawn from the cylinder tube l flows from the reservoir chamber 7 via the first communication passage 402 of the base 4. It flows into the lower liquid chamber Ib.

At this time, in the piston 5, a damping force is generated in the first stage disc valve 5d, the second stage disc valve 5g, and the second communication passage 503 according to the piston speed.

The respective damping force characteristics will be explained based on FIG. 6.

FIG. 6(A) shows the damping force characteristics of the first-stage disc valve 5d, and the first-stage disc valve 5d usually comes into contact with the first seat surface 505 and completely closes the second communication path 503. It is in a closed state. Therefore, in the first stage disc valve 5d, after the valve is opened, the speed first becomes a characteristic of the 2/3 power.

As shown in this figure, even at extremely low speeds, a larger damping force can be obtained compared to the one with a constant orifice.

When the amount of deflection of the first stage disc valve 5d increases and it comes into contact with the stopper plate 5f, the elastic force increases and the slope of the characteristic becomes steeper. In this figure, the inflection point a indicates the time when the first stage disc valve 5d comes into contact with the stopper plate 5f.

Furthermore, to add an explanation at low speeds, FIG. 8 shows the hydraulic fluid flow rate immediately after stroke switching at low speeds, and the dotted line shows the case with a constant orifice. In this case, the flow iiQ is proportional to the square of the pressure change ΔP. In addition, the solid line indicates the case of this embodiment, and the flow rate Q is proportional to the 2/3 power of the pressure change ΔP.As shown in the figure, the flow rate at the rise immediately after stroke switching is large. In other words, in the embodiment, the responsiveness of the damping force is high.

Next, Fig. 6 (b) shows the damping force characteristics of the second stage disc valve 5g, and this valve 5g is in a closed state while the piston speed is low, and the hydraulic fluid is constantly flowing. It passes through orifice 508. Therefore, as shown in the figure, the characteristics of this constant orifice 508 are as follows. It has a speed squared characteristic, and the damping force is low at low speeds.

Then, when the piston speed becomes high and the second stage disc valve 5g is opened, the speed becomes a 2/3 power characteristic. Incidentally, the inflection point S indicates the time when the second stage disc valve 5g is opened.

Next, FIG. 6(C) shows the damping force characteristics of the second communication passage 503, and this second communication passage 503 has a speed squared characteristic in which almost no damping force is generated while the piston speed is low. It becomes.

In this way, in the extension stroke, the above-mentioned characteristics are obtained in each part, and in particular, in the first stage disc valve 5d,
Since a speed 2/3 power characteristic with a good rise from extremely low speeds can be obtained, the combined characteristics are as shown in Figure 7.
The damping force characteristic is a nearly straight line.

If such characteristics are obtained, when applied to an automobile suspension, it will be possible to respond with good response to changes in vehicle body posture with low piston speed, such as when turning the steering wheel, thereby improving handling. It also has an excellent 1-distribution effect against bouncing at low piston speeds, such as when traveling at high speeds. moreover,
In this way, the characteristic is almost linear, and conventionally (Fig. 13)
As the characteristics do not have an inflection point in the middle, the characteristics change suddenly at the piston speed near the inflection point,
There is no problem such as a decrease in steering stability.

Furthermore, in this embodiment, the piston 5 and the guide member 2 are provided with a seamless piston ring 11 and a seal ring 1.
2 are provided. Therefore, when the piston 2 slides in the extension direction, the hydraulic fluid in the upper fluid chamber la may flow into the lower fluid chamber 1b through between the piston 2 and the cylinder tube l, or It is difficult for the hydraulic fluid to flow into the liquid reservoir chamber 10 through the piston rod 8, and as a result, almost the entire amount of the moving hydraulic fluid from the upper liquid chamber la moves through the second communication path 503.

That is, FIG. 9 shows a configuration in which such a piston ring 11 and a seal ring 12 are provided (indicated by a solid line: this embodiment).
This is a comparison between 1 and 2 (indicated by the dotted line).
As shown in this figure, if there is any leakage in the piston 5 and the guide member 2, this leakage causes an effect similar to that of constant orifices provided in parallel, and the rise is delayed as shown in the figure. In contrast, in this embodiment, no leakage occurs, so the response is excellent as shown in the figure.

(II) When the piston 5 slides on the pressure surface (in the direction of narrowing the lower liquid chamber 1b) during the pressure stroke, the first communication passage 502 of the piston 5 is used to equalize the liquid pressure difference between the upper and lower liquid chambers 1a and 1b. The hydraulic fluid flows through the cylinder tube l, and the hydraulic fluid flows in an amount corresponding to the volume of the piston rod 8 entering the cylinder tube l.
The liquid flows into the reservoir chamber 7 from the lower liquid chamber ib via the second communication path 403 of the base 4 .

At this time, in the base 4, a damping force is generated in the first stage disc valve 4e, the second stage disc valve 4c, and the second communication passage 403 according to the piston speed.

The generation of this damping force is similar to the case described above. When the first stage disc valve 4e opens, first a damping characteristic of the speed 2/3 is obtained in the low speed range, and then this first stage disc valve 4e 4e comes into contact with the second stage disc valve 4c, the generated damping force increases and the slope of its characteristics becomes steeper.

On the other hand, the second stage disc valve 4c does not open in the low speed range, and obtains a speed square characteristic due to the constant orifice 408, and changes to a speed 2/3 characteristic from the time of opening.

Further, in the second communication path 403, in a low speed range, the speed square characteristic is such that almost no damping force is generated.

Even during this pressure stroke, the seal ring 12 prevents leakage, resulting in high responsiveness.

Next, a second embodiment shown in FIGS. 10 and 11 will be described.

In this embodiment, annular grooves 1515a and 25a are formed on the inner surface of the piston ring 15 and the outer surface of the piston body 25.
A plurality of grooves 15a and 25a are formed in parallel, and the grooves 15a and 25a fit into the grooves.

Further, in the guide member 22, the liquid storage chamber lO and the reservoir chamber 7 are communicated with each other through a communication hole 22a.

Note that the other configurations are the same as those in the first embodiment, so explanations will be omitted. Also, the same reference numerals indicate the same objects.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, the present invention was applied to both a disc valve that generates a damping force in the extension stroke and a disc valve that generates a damping force in the compression stroke (the structure did not have a constant orifice). It may be applied to only one of them.

In addition, in the embodiment, only the first-stage disc valve has a structure without a constant orifice, but either of the first-stage and second-stage disc valves may have a structure without a constant orifice, or both may have a structure without a constant orifice. It may also be a structure.

Further, in this embodiment, the disc valve has a two-stage valve structure, but it may have a one-stage disc valve structure.

In addition, although the piston ring and seal ring are made of polychlorotrifluoroethylene in the embodiment, they may be made of other resins, metals, etc., or they may be made of different materials. good.

(Effects of the Invention) As explained above, in the hydraulic shock absorber of the present invention, since the piston ring and the seal ring are provided,
Since the disc valve that opens in the low speed range has a structure that does not have a constant orifice, the damping force rise characteristic in the low speed range can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a hydraulic shock absorber according to a first embodiment of the present invention;
Figure 2 is a detailed view of part A in Figure 1, Figure 3 is a detailed view of part B in Figure 1, Figure 4 is a detailed view of part C in Figure 1, Figure 5 is a detailed view of part 1, and Figure 6 is a detailed view of part C in Figure 1. 1 is a graph showing the damping force characteristics on the piston side of the first embodiment, in which (a) is the characteristic of the first stage disc valve, (b) is the characteristic of the second stage disc valve, and (c) is the characteristic of the second stage disc valve. Fig. 7 shows the characteristics of the passage, and Fig. 7 is a graph showing the damping force characteristics of the hydraulic shock absorber of the first embodiment. Fig. 8 shows the pressure difference and valve flow rate of the first stage disc valve on the piston side of the first embodiment. FIG. 9 is a graph showing the rising portion of the damping force in the first embodiment, and FIG. 10 is a sectional view showing the piston of the second embodiment. FIG. 11 is a sectional view showing the guide member of the second embodiment;
Figure 2 is a graph showing conventional damping force characteristics. E9th disc valve 503...Second communication passage 7...Reservoir chamber 8...Piston rod 11...Piston ring 12...Seal ring Patent application Damping force of Hitotatsugi Auto Parts Co., Ltd. It is a graph showing characteristics. ■...Cylinder tube 1a...Upper liquid chamber Ib-...Lower liquid chamber 8th factor e,>>θ Fig. 9 Fig. 6 0.1 0.6 Piston movement Fig. 11/ 0.1 ○ 3 Piston movement

Claims (1)

[Claims] 1) A cylinder tube whose one end is sealed by a guide member and whose other end is sealed from a reservoir chamber by a base, and a cylinder tube provided at the tip of a piston rod guided by the guide member. , a piston that divides the inside of the cylinder into an upper liquid chamber and a lower liquid chamber; a communication passage formed in the piston to communicate the upper liquid chamber and the lower liquid chamber; and a communication passage formed in the piston to communicate the lower liquid chamber and the reservoir chamber. a disc valve that is provided in at least one of the communication passages formed in the base and that opens to generate a damping force when hydraulic fluid flows through the communication passage, the disc valve being configured to operate in a low speed range. A seamless piston ring is provided on the outer periphery of the piston to seal between the liquid chambers between the piston and the cylinder tube, and the guide member has an upper liquid chamber and an upper liquid chamber. A hydraulic shock absorber characterized by having a seamless seal ring that seals the outside of the cylinder tube. 2) The seal ring is in close contact with the piston rod, has a distance from the guide member that can follow the eccentricity of the piston rod, and has a position regulating member provided on the guide member that prevents the piston from moving. 2. The hydraulic shock absorber according to claim 1, wherein axial movement of the rod is restricted.