JPS6018860B2 - Vehicle shock absorber - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in shock absorbers for vehicles.

More specifically, a piston is provided at the tip of the rod that defines the interior of the inner cylinder and has a return passage for oil during the compression process and a closing passage for oil during the tension process, and the piston is equipped with a plate-shaped check valve and a slide valve. A fixed orifice is attached to the check valve, and the gap formed by the orifice, the main passage, the upper surface of the slide valve, and the lower surface of the piston is
The present invention relates to a shock absorber for car tuna that has improved damping properties as a shock absorber by combining two throttle mechanisms to obtain arbitrary damping force characteristics in the low speed range, medium speed range, and high speed range of the piston.

(Prior Art) Various types of tine hydraulic shock absorbers, which are a combination of a hydraulic damping device and an elastic member such as a coil spring, have been adopted as bran shock absorbers.

Such a shock absorber includes a piston that slides within an inner cylinder, a main orifice and return oil passage bored in all directions of the axis of the piston, and a check valve that is provided on the top surface of the piston and opens during its compression stroke. A type of shock absorber is proposed that includes a slide valve that is provided on the lower surface of the piston and opens during the tension stroke of the shock absorber.

In such a shock absorber, the tension stroke of the piston is caused by the oil in the upper chamber divided by the piston flowing into the main orifice as the piston rises, and this inflowing hydraulic pressure causes the slide to block the lower surface entrance of the main orifice. The valve is opened against the valve spring, and a predetermined damping force is obtained by controlling the amount of movement of the slide valve and the amount of oil by the main orifice, thereby providing a hydraulic damping effect.

In addition to the above, such a shock absorber has also been adopted, in which a groove is provided in the radial direction at the closed end of the upper surface of the return oil passage, and a fixed orifice is provided in the radial direction between check valves that close the entrance end of the upper surface of the oil passage. . (Problem to be Solved by the Invention) In general hydraulic shock absorbers including the above types, in the shock absorbing operation, the piston stroke is small at the time of low piston speed, initial damping, and the piston is at high speed when the piston is at low speed. If the slope of the damping force curve is set to a small value in the same manner as in the area, a so-called fluffy cushioning will occur due to the undulations and ups and downs of the road surface.

Therefore, if the slope of the damping force characteristic curve is set to a large value, the spring will be compressed by the impact of small irregularities, and then when it returns to its original state, the expansion speed will be regulated by a large damping force. Therefore, the next impact occurs before the vehicle has sufficiently touched the road surface, and the shock absorbing movement of the small impact cannot be effectively performed, which affects ride comfort to some extent. Furthermore, if the damping force of the piston is increased and kept constant, it will not be possible to obtain the necessary and desirable damping force characteristics in the piston high speed range and large stroke range. This is the same for the types with check valves and slide valves mentioned above; the main orifice opens with the slide valve during the tension stroke, and damping force is obtained from this main orifice, but with only this main orifice, it is not possible to maintain steady damping force. However, the same problem as above occurs.

Also, this type has an opening on the check valve and the top of the piston □
A fixed orifice is provided in the radial direction of the piston between the return oil passages, and even if it is attempted to obtain highly accurate damping force retention at low speed pistons, etc., the orifice will not move in the direction of hydraulic pressure. Because they are installed at right angles, the oil flow resistance is large and highly accurate damping force characteristics cannot be obtained.
On the other hand, it can be said that it is desirable for a shock absorber in a car shrine to have the following characteristics.

First of all, when cushioning the impact caused by small irregularities on the road surface, that is, when the piston speed during the tension stroke is in the low speed range, it is not desirable to use a so-called fluffy cushioning that allows the occupants to feel the vibrations caused by the impact forever. It is desirable to have a function to control (dampen) the vibrations. In other words, the larger the slope of the damping force retention curve, the better. Next, when cushioning the impact caused by moderate irregularities, that is, when the piston speed during the tension stroke is at a medium speed, even higher ride comfort is required.
In order to improve this, it is desirable to have a function that regulates the expansion speed of the shock absorber with a certain degree of damping force, regardless of slight changes in the piston speed.

In other words, the smaller the slope of the damping force curve, the better. Furthermore, when buffering the impact caused by very large irregularities, that is, when the piston speed during the tension stroke is in a high speed range, small changes in piston speed are necessary to prevent the shock absorber from reaching its full extension from the standpoint of maneuverability. An extremely large damping force is required, and it is desirable to have a function capable of retaining that large damping force.

In other words, the larger the slope of the damping force retention curve, the better. (Purpose of the Invention) In view of the above-mentioned problems in shock absorbers for automobiles, especially shock absorbers having plate-shaped check valves and slide valves, the present inventors have developed the present invention in order to effectively solve these problems. This is what I did.

The purpose of the present invention is to eliminate the fluffy feeling of the buffering operation at low piston speeds such as small impacts and small strokes, to obtain preferable damping force retention at low piston speeds, and to We have developed a shock absorber for vehicle sections that can obtain a predetermined damping force regardless of slight changes in piston speed, and can also obtain desirable damping force characteristics required even in high piston speed and large stroke regions. provide.

(Means for Achieving the Object) In order to achieve the above object, the present invention provides a check valve that opens the return oil path formed in the axial direction of the piston during the compression stroke, etc., with a fixed orifice that is compatible with the return oil path. As a result, it has a simple structure and is easy to process, and can be implemented without making major changes to similar types of shock absorbers, making it a shock absorber with excellent practicality and good performance. To provide a shock absorber for wheels which can be obtained at low cost.

(Embodiment) A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Figure 1 shows a side sectional view of the shock absorber, and although it is shown horizontally in the figure, this is because the shock absorber is long in the direction of Yuzu, and in reality it is attached to the Kurumase with the left side facing up and the right side facing down. Fig. 2 is an exploded perspective view of the piston part, Fig. 3 is an exploded perspective view of the bottom part, Figs. The figure is a cross-sectional view of essential parts for explaining the operation.

The shock absorber 1 is composed of inner and outer double cylinder bodies 2 and 3, with an inner cylinder 2
The upper end of and the upper part of the outer cylinder 3 are closed with a rod guide 4,
The upper end of the outer cylinder is closed with a lid 5, and the lid plate 5 and the rod guide 4 are closed.
A rubber seal member 6 is interposed therebetween to seal between the rod guide 4 of the rod 9, which is slidably slidable in the axial direction of the inner cylinder 2, and the cover plate 5.

The bottoms of the inner and outer cylinders 2 and 3 are closed with a bottom member 7, and there is a reservoir S between the inner and outer cylinders 2 and 3, and an oil chamber S inside the inner cylinder 2.
2 is formed, and the chambers S, , S2 are connected to a bottom valve 3 which will be described later.
0 is suitable for lotus. The upper part of the rod 9 extends outside the lid plate 5, and is attached to the upper end of the rod 9 on the body side of the car ball.A bracket 8 is integrally extended to the bottom of the bottom member 7 in all directions, and is automatically If it is a two-wheeled vehicle, attach it to the rear wheel axle, etc. A piston flock 10 is provided at the lower end of the rod 9 facing into the inner cylinder 2. Specifically, a small diameter attachment portion ga is provided at the tip of the rod 9, and a valve stopper 1 which also serves as a spring receiver is provided on this.
1, then piston 12, then nut 13
are sequentially joined and screwed together, and a stopper 11, a piston 12, and a nut 13 are fixed to the rod attachment portion 9a in this order from above, and 14 is a piston ring fitted around the outer periphery of the piston 12. With this piston 12, the chamber S2 in the inner cylinder 2 is the upper chamber S.
It is divided into a lower chamber S4 and a lower chamber S4. A plurality of main orifices 15, for example three main orifices 15, which penetrate the piston 12 in the axial direction and close on the upper and lower surfaces of the piston, are formed radially.
Also, three arcuate and elongated return oil passages 16 are similarly formed radially outside the main orifices 15. On the upper surface of the piston 12, a portion corresponding to the upper end entrance of the main orifice 15 on the inner diameter side is an annular-like oil passage 17 recessed in all directions of the axis. It may be formed in an annular shape, or it may be provided radially at an appropriate angle to form a discontinuous annular oil passage.
In either case, the oil passage 17 has a main orifice 15...
・Make sure that the upper end of the opening is facing you. As a result, the outer peripheral portion of the upper surface of the piston protrudes in all axial directions like a circular embankment, and the annular protrusion 18 closes the upper end of the return oil passage 16. The main orifice 15 is located on the bottom surface of the piston 12.
- A ring-shaped slide valve 19 that closes only the lower end of the nut 13 is mounted so that it can slide along the guide portion 13a of the nut 13, and a flange portion provided on the lower surface of the valve 19 and the lower end of the nut 13. A valve spring 20 is compressed between 13b, and the valve 19 elastically closes the lower end of the main orifice 15 due to this spring force.

Further, a large-diameter closing portion 15a that widens downward is formed at the lower end of the main orifice 15, and the valve 19
The pressure receiving area is set large. This checkpoint section 15a
This facilitates and ensures the setting of the hydraulic pressure acting on the slide valve 19 through the main orifice 15 during the high-speed piston tension stroke, so that the slide valve 19 opens the main orifice 15 at a predetermined hydraulic pressure, that is, at a predetermined speed of the piston. It is for the purpose of A check valve 21 is disposed on the upper surface of the piston 12, and the valve 21 is formed of a plate material as shown in FIG. The inner flap portion of the piece 21b comes into contact with the outer light portion of the hanging cylindrical guide portion 11a of the stopper 11, and the valve 2
This piece 21b is fitted with iron so that it can move freely in the 1' axis direction.
・In between is the annular oil passage 1 of the main orifice 15...
7 and a through hole a for moving the oil chamber S3 on the top surface of the piston.
・are formed radially.

Further, the annular protrusion 18 formed on the upper surface of the piston has a recess that is formed radially in an arc shape, is disposed on the same circumference, and allows the closed upper ends of the return oil passages 16 to pass through each other. 22 is formed in a groove shape, the ring portion 21c of the check valve 21 is placed on the upper surface of the protrusion 18, and the return oil path 16...
- and the recessed part 22... are closed with the closing valve 21.

A valve spring 23 is disposed between the valve 21 and the flange portion lib of the stopper 11, and this spring 23
As shown in FIG. 2, the valve 21 is formed of a ring-shaped leaf spring whose side surface is bent into a V shape, and the valve 21 comes into elastic contact with the upper surface of the protrusion, as described above, and the return oil path I6...
・Close the upper end entrance and the lotus passage recess 22... The ring portion 21c of the above plate-shaped check valve 21 is provided with a fixed orifice 24 penetrating in the vertical direction, and this orifice 24 is preferably a circular hole as shown in the figure, and in the illustrated example, one such orifice is provided. Two or more may be used, and an appropriate number is provided depending on the piston diameter, the cross-sectional area of the orifice, etc. in order to obtain the damping force performance described later. The fixed orifice 24 is provided in the axial direction on the same circumference as the open upper end of the return oil passage 16 which is closed by the check valve 21 and the lotus recess 22 that connects the closed end thereof. Therefore, the fixed orifice 24 and the return oil passage 16 are in communication. A bottom valve 30 is provided at the bottom of the inner cylinder 2, and a bottom valve body 31 is located on the bottom member 7 to partition the inner and outer cylinders 2 and 3. - A lotus passage 32 is formed to accommodate the outer cylinders 2 and 3. At the center of the body 31 is a fixed orifice 33 that connects the lower chamber S4 of the piston 12 and the hanging passage 32, and on the outer periphery of this orifice is an annular protrusion 31.
A is formed in the protrusion 31a, and a plurality of passages 34 are radially provided in the protrusion 31a so as to extend between the lower chamber S4 and the reaching passage 32. A ring-shaped check valve 35 made of a plate material is disposed on the annular protrusion 31a, and between the ring-shaped clip 37 and the check valve 35 is a ring-shaped plate bent into a V-shaped side surface like the check valve spring 23. A spring-like spring 36 is intervened, and the spring 36 causes the check valve 35 to close the upper end opening of the passage 34.

In addition, 40 in the drawing is a buffer spring for the piston 12.

Next, to explain its operation in detail, the compression stroke is as shown in Figure 9, and is similar to this type of buffer, and the initial stage of compression is the first
In the state shown in the figure, the piston 12 moves to the right (descends), and the oil in the lower chamber S4 flows from the fixed orifice 24 of the check valve 21 to the upper chamber S3 via the return oil passage 16...
It flows into the reservoir chamber S through the solid orifice 33 of the bottom valve 30.

As the oil pressure increases as the stroke progresses, check valve 2
1 is lifted against the spring 23, and as a result, the return oil passages 16... are opened, and the oil flows as shown by the arrow in FIG. 9, thereby obtaining a predetermined damping force in the compression stroke. Next, to explain the tension stroke, the low speed of the piston in the tension stroke, that is, the tension load as a reaction to the initial compressive load,
When the piston is at low speed, such as a tensile load with a small stroke or a buffering effect of bumps on the road surface when traveling on a general road surface, the oil in the upper chamber S3 as the piston rises passes through the fixed orifice 24 provided in the check valve 21. The oil returns to flow into the oil passage 16.

Even if the check valve 21 rotates during this inflow, the oil passage 16 or the lotus recess 22 remains under the fixed orifice 24.
・Since the fixed orifice 24 and the oil passage 16 are located
The distribution of ... will be carried out without approval. At the beginning of the piston 12's tension stroke, as shown in FIG.
In the speed range and load range before the opening of the fixed orifice 24, a large damping force is obtained.

For this reason, in the case of a low piston speed castle, the buffering effect in this area is performed with a large damping force, and the bouncy feeling caused by the buffering motion caused by small irregularities on the road surface is prevented, and also before the slide valve 19 is released. The damping motion with a small stroke and small load effectively improves the riding performance with the above-mentioned large damping force. In addition, in the medium speed range of the piston 12, that is, in the medium speed range from the low speed range to the high speed range, the hydraulic pressure flowing into the main orifice 15 increases, causing the slide valve 19 to resist the spring 201. It begins to be pushed open, and a gap is formed between the upper surface of the slide valve 19 and the lower surface of the piston block 10, and at the same time, a damping force by the main orifice 15 begins to be generated.

However, since the damping force due to the gap is larger than the damping force due to the main orifice 15, only the damping force retention due to the gap appears, and therefore, the expansion speed of the shock absorber 1 is regulated by a certain predetermined damping force, and the damping force is further increased. Provides ride comfort. Further, when the piston 12 reaches a high speed, that is, a large stroke, the hydraulic pressure flowing into the main orifice 15 increases, and this hydraulic pressure pushes the slide valve 19 open against the spring 201.

The opening movement of this slide valve 19 is caused by the main orifice 15.
By controlling the opening area of the large-diameter closed portion 15a formed at the lower end of the piston, the piston can be reliably operated at a predetermined speed. The upper and lower chambers S3 and S4 are communicated through the main orifice 15..., and the oil in the upper chamber S3 is controlled by the main orifice 15 and fixed orifice 2.
The damping force retention property corresponding to this is obtained as the sum of the cross-sectional areas of 4, and the slope of the damping force retention curve is smaller than that in the low speed castle and larger than that in the medium speed castle due to this main orifice 15... Become. This state is shown in FIG. 8, with arrows indicating the flow of oil. To explain the above with the graph in Figure 10, the graph shows actual measured values used as a rear shock absorber for a motorcycle, with the horizontal axis showing the piston speed (k/sec) and the vertical axis showing the damping force (k9). It is something.

As shown in the figure, in the micro-vibration region where the piston speed is within 0.1 kite/second, the damping force decreases in this range, that is, in the piston low speed region, due to the action of the fixed orifice 24, as shown by curve C. The damping force increases exponentially as the rate of increase increases. When the piston speed exceeds the halfway point of 0.1/sec, the slide valve 19 begins to open very slightly, and a gap is formed between the top surface of the slide valve 19 and the bottom surface of the piston block 10, and the damping due to the gap occurs. Strength appears. That is, the piston speed is 0.
At a medium speed castle between the center bending point and the mouth of about 3 m/sec, the rate of increase in the damping force becomes smaller than that described above, and increases as shown by curve A'. When the piston speed exceeds the mid-break point of around 0.3 m/sec, the slide valve 19 that closes the orifice 15 is further opened, and the main orifice 15 is opened.
Due to this action, the rate of increase in damping force in the piston speed range after this point is smaller than in the low speed range and larger than in the medium speed range, and increases exponentially as shown by curve A. In this way, the damping force increases in a squared manner up to the halfway point in the piston's low speed range, and the damping force is not sufficient to withstand slight vibrations during normal driving or small impact loads due to uneven road surfaces that occur in this region. In order to suppress the fluffy feeling, in the mid-to-long range, the damping force characteristics of the gap regulate the expansion speed of the shock absorber 1 with a certain predetermined damping force, regardless of slight changes in the piston speed, and the piston is able to operate at high speeds and has a large stroke. In order to correspond to this, the damping force in the area is set smaller than the low speed castle and larger than the medium speed castle,
We were able to obtain good damping force characteristics over the entire piston speed range. Furthermore, the damping force retention properties in the low speed range, medium speed range, and high speed range are determined by the diameter of the fixed orifice 24, respectively.
Since the diameter of the main orifice 15 and the elastic modulus of the valve spring 20 can be set independently and freely, a desired damping force retention curve can be easily obtained, and therefore it can be applied to a wide variety of models. .

Although the absolute values are shown in the graph, this is to specifically show the actual measured values for motorcycles, and although the values may change for four-wheeled vehicles, the preferred damping values as shown in the curve in the graph force characteristics can be obtained.

Next, in the shock absorber of the above embodiment, by setting the conditions of the piston block including the check valve, piston, main orifice, etc. as follows, the above-mentioned characteristics of the shock absorption can be further improved, and the damping force retention property can be stabilized. The present inventors conducted experiments on the buffer under various conditions and obtained measured values that can be applied to various conditions as described below. The first problem concerns a solution to noise generation during the damping action of the buffer.

When the damping force described above is applied, the flow rate of oil passing through the main orifice is determined by the diameter of the piston. Therefore, if the diameter of the main orifice is narrowed down to a smaller diameter than necessary, and the flow velocity flowing through the main orifice is made farther than necessary, the
That is, the pressure difference becomes large before and after the main orifice portion of the piston, which tends to cause turbulence in the flow in the reservoir. This causes hydraulic vibrations, and these turbulent flows and hydraulic vibrations cause noise, which is emitted to the outside as noise during the damping action of the shock absorber. As a result of various experiments, actual measurements, and studies regarding the relationship between these noise generation conditions, the piston area, and the single cross-sectional area of the main orifice, we found that the ratio of the piston area and the fixed or main orifice cross-sectional area is as shown in Figure 11. It was discovered that there is a certain relationship between noise generation conditions.

Here, we set the cross-sectional area of the piston as A2 and the single cross-sectional area of the main orifice as A2, and conducted experiments by setting various ratios of these areas, and obtained results as shown in the graph in Figure 11. .

In the figure, the vertical axis represents noise, and the position where the noise is low and stable is 1.
00 and is expressed in % with this as a reference, and the horizontal axis is expressed as A2/A2×10-3), that is, the ratio of the single cross-sectional area of the main orifice/the cross-sectional area of the piston (×10-3).

As is clear from the line C in the graph, when the ratio of A3/A2 is less than 1.0×10-3, which is the extreme point 2, the noise increases exponentially, and when the ratio of A3/A2 is less than the extreme value point 2, the noise increases exponentially. With the value of A2, the sound pressure is stable at the same level, the noise is small, and a stable sound pressure bell can be obtained.

Therefore, the ratio between the fixed or main orifice single section light and the piston section light A2 is A3/n≧1.0×10-
3 was found to be preferable in terms of noise reduction during the damping action in the shock absorber of this embodiment.

The second issue relates to the damping force retention property of the shock absorber during the damping action, particularly stabilization of the damping force characteristics in the piston high speed range.

When the damping force is generated, the check valve is disposed on the upper surface of the piston, and a gap is formed between the check valve and the piston, that is, the notch-like passage of the check valve in the above embodiment and the outer diameter of the stopper 11. Oil flows into the closing orifice through the gap, but when the piston is at high speed, the check valve spring is deformed flat by hydraulic pressure, which changes the flow cross-sectional area and stabilizes the damping force characteristics when the piston is at high speed. This will have some impact. Therefore, the inventors of the present invention conducted experiments and actual measurements while varying the total cross-sectional area of the main orifice and the total cross-sectional area of the effective passage through the through holes of the check valve under various conditions. It was also found that a certain relationship holds true in the same manner as above.

That is, as shown in the graph of FIG. 12, where A5 is the total cross-sectional area of the effective passages of the check valve, and is the total cross-sectional area of the main orifice of the piston, the ratio of the two is A5/
When various settings were made and actual measurements were taken, actual measured values were obtained as shown in the curved tree shown in Figure 12.

Fig. 12 shows the damping force on the vertical axis, and the position where the damping force is stable is 100, and it is expressed in % with this as a reference. It is expressed as a ratio of the total cross-sectional area of . As is clear from the curve tree, the ratio of A5/A4 is 20 to the extreme point.
Above this value, the damping force becomes constant and stable, but below this value, the damping force increases exponentially and fluctuates within the area of the previous ratio to the extreme point of the curve E, and There was a mirror direction that changed the damping force.

Therefore, the ratio of the total cross-sectional area of the effective passages of the check valve to the total cross-sectional area of the main orifice is 20 to stabilize the damping force retention of the shock absorber according to this embodiment.
It has been found that this is particularly advantageous in terms of stabilizing damping force retention at high piston speeds.

The third aspect relates to stabilizing the damping force of the shock absorber and reducing noise during the damping action. As described above, the flow rate of oil passing through the main orifice during the damping action is determined by the diameter of the piston, and as the piston diameter increases, the flow rate passing through the main orifice increases.

In this case, if the inflow side of the main orifice is closed while remaining flat, the inflow resistance will increase, which will affect the smooth flow of oil into the main orifice, and as mentioned above, there will be a large pressure difference before and after the piston. As a result, turbulent flow and hydraulic vibration occur, causing noise and becoming a factor that affects damping force retention. Therefore, in this embodiment, an annular oil passage 17 is provided in the main orifice opening □ on the upper surface of the piston.
This stabilizes the flow of oil into the main orifice, and then guides the oil to the main orifice.
In this way, there is a correlation between the diameter of the piston and the amount of oil passing through the main orifice, and by providing an annular oil passage on the inflow side of the main orifice, the inflow of oil is stabilized. Experiments and actual measurements under various setting conditions have revealed that the oil sump effect caused by the axial height of the road and the resulting smoothing of the oil streamlines also affect the stabilization of damping force retention and noise reduction.

That is, when the height of the annular oil passage is h and the diameter of the piston is D, various ratios h/D between the two were set, experiments were conducted, and actual measurements were performed, and the results were obtained as shown in the graph of Figure 13. .

In Figure 13, the vertical axis is the damping force, the position where the damping force is stable is 100, this is expressed as a percentage, and the machine axis is h.
/D, that is, the ratio of the height of the annular oil passage to the diameter of the piston.

As is clear from curve A, when the ratio h/○ exceeds the extreme value of 0.08, the damping force becomes constant and stable, but below this, the damping force increases exponentially, and the There was a forehead direction that fluctuated within the range below the value point and the damping force changed. Therefore, it is preferable for the ratio of the height h of the annular oil passage to the height D of the piston to be h/D≧0.08 in order to stabilize the damping force characteristics of the shock absorber of this embodiment. decreased.

In the above, it is sufficient that the diameter is larger than the diameter of the main orifice of the annular oil passage 17.

(Effects of the Invention) As is clear from the above description, according to the present invention, it is possible to apply a damping force at low piston speeds and set the damping force to a large value. It is possible to perform the shock-absorbing effect at the low speed of the piston in an optimal state, eliminate the shock-absorbing effect that gives a fluffy feeling, and also prevent the direct propagation of minute vibrations, improving ride comfort. You can get a shock absorber.

Furthermore, according to the present invention, although it is possible to obtain the preferable damping force retention property as described above at a low piston speed castle,
In the piston medium speed castle, due to the gap between the slide valve and the piston block, it is possible to obtain a predetermined damping force that regulates the expansion speed of the shock absorber regardless of slight changes in the piston speed. It is possible to obtain desirable damping force characteristics required even in a large stroke region, and it is possible to obtain a high-performance shock absorber having damping force characteristics optimal for each region over the entire range of piston speeds. Furthermore, according to the present invention, the above can be achieved by simply providing the piston with a fixed orifice that is compatible with the return oil passage in the check valve that opens and closes the return oil passage, making it possible to make major changes to the secondary shock absorber. As mentioned above, a shock absorber with good performance can be provided with a simple structure and at a low cost, and the fixed orifice can be formed by simply drilling a hole in a plate-shaped check valve. is easy.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; Fig. 1 is a side sectional view of the entire shock absorber, Fig. 2 is an exploded perspective view of the piston block, Fig. 3 is an exploded perspective view of the bottom valve, and Fig. 4 is an exploded perspective view of the bottom valve. FIG. 1 is a sectional view taken along the line 4-4, FIG. 5 is a sectional view taken along the line 5-5, FIG. 6 is a sectional view taken along the line 6-6, and FIGS.
Figure 7 is a sectional view of the main part of the piston low speed castle during the tension stroke.
Fig. 8 is a cross-sectional view of the same high-speed castle, Fig. 9 is a cross-sectional view of the same during the compression stroke, Fig. 10 is a graph showing the damping force retention property of the shock absorber according to the present invention in the tensile stroke, and Fig. 11 is the same cross-sectional view of the same high-speed castle. A graph showing the influence of the ratio of the single cross-sectional area of the orifice to the piston cross-sectional area on noise, and Figure 12 shows the influence of the total cross-sectional area of the check valve's effective passage and the total cross-sectional area of the main orifice on damping force retention. FIG. 13 is a graph showing the influence of the height of the annular oil passage and the piston diameter on damping force retention. In the drawing, 1 is a shock absorber, 2 is an inner cylinder, 3 is an outer cylinder, 9 is a rod, 10 is a piston block, 12 is a piston, 15 is a main orifice, 16 is a return oil passage, 17 is an annular oil passage,
19 is a slide valve, 21 is a check valve, 24 is a fixed orifice, and S3 and S4 are upper and lower chambers. Fig. 2 Fig. 3 Fig. 1 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 2 One person's stamen 1re'Buddha J False fake figure 12 Yumi force Hara 1 He is stock'Buddha' Other skin night mouse shadow miso total liquid? Needle/target rll before 1st liquid Fig. 13/Minoriki character remaining strike ■ Ku'

Claims (1)

[Claims] 1 Equipped with an inner and an outer cylinder, a piston block provided at the tip of the rod is slidably fitted into the inner cylinder, and the piston block has a return passage through which oil flows during the compression stroke, and a return passage through which oil flows during the tension stroke. In a vehicle shock absorber having at least two main oil passages through which oil flows, a plate-shaped check valve that is pressed by an elastic member is provided on the upper surface of the piston block, and the return passage can be opened and closed by the check valve, The check valve is provided with a fixed orifice that communicates with the return passage, and the main passage is configured as an orifice that has an oil throttling function.A slide valve that is made elastic by an elastic member is provided on the lower surface of the piston block. The passage can be opened and closed freely, and an arbitrary damping force characteristic curve can be obtained by combining three throttling mechanisms: the fixed orifice, the main passage, and the gap formed by the upper surface of the slide valve and the lower surface of the piston block. A vehicle shock absorber featuring: