KR100211201B1 - Damping force adjustable type hydraulic shock absorber - Google Patents

Abstract

In the damping force adjustable hydraulic shock absorber, the degree of freedom in setting the damping force characteristics is increased. The piston 5 which connected the piston rod 6 to the cylinder 2 is inserted, and the reservoir 4 is connected through the check valve 16. FIG. Cylinder The lower chambers 2a and 2b communicate with each other by the cycle oil passage 11, and the disc valve 12 is provided in the oil passage 11. The cylinder upper chamber 2a and the reservoir 4 are communicated through the damping force adjusting mechanism 17. During all expansion and contraction of the piston rod 6, oil flows from the cylinder upper chamber 2a to the reservoir 4 through the damping force adjusting mechanism 17, and the damping force is generated by the damping force adjusting mechanism 17. do. At the time of the contraction stroke, oil flows from the cylinder lower chamber 2b to the cylinder upper chamber 2a via the oil passage 11, and the damping force is also generated by the disc valve 12. Since the damping force characteristic on the contraction side changes depending on the characteristics of the disc valve 12, the degree of freedom in setting the damping force characteristic can be increased.

Description

Damping Force Adjustable Hydraulic Shock Absorber

The present invention relates to a damping force adjustable hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile.

BACKGROUND ART A hydraulic shock absorber mounted on a suspension device of a vehicle such as an automobile includes a damping force adjustable hydraulic shock absorber capable of appropriately adjusting the damping force in order to improve ride comfort and steering stability in accordance with road conditions, driving conditions, and the like.

The damping force adjustable hydraulic shock absorber includes, for example, a cylinder in which oil (oil) is enclosed, a reservoir in which oil and gas are enclosed, as described in Japanese Utility Model Laid-Open No. 50-77685, and inserted into the cylinder. A piston partitioning into two chambers, a cylinder upper chamber and a cylinder lower chamber, a piston rod having one end connected to the piston and the other end extending outward through the cylinder upper chamber, A communication path for communicating between the lower chambers, a check valve allowing flow of oil from the cylinder lower chamber to the cylinder upper chamber, a communication path for communicating the cylinder lower chamber and the reservoir, and the reservoir side of the communication path. A check valve allowing the flow of oil to the lower chamber of the cylinder, a main passage communicating the cylinder upper chamber and the reservoir, and a damping force adjusting valve for controlling the flow of oil in the main passage and adjusting the flow resistance appropriately. There is something done.

According to this configuration, at the time of stretching stroke of the piston rod, The check valve between the lower chamber is closed and the oil in the upper chamber of the cylinder is pressurized. During the contracting stroke, the check valve between the cylinder lower chamber and the reservoir is closed and the cylinder rod is intruded by intrusion of the piston rod. Since the lower chamber is pressurized, the oil flows through the main passage from the upper chamber to the reservoir in all the expansion and contraction, and the damping force is generated by the damping force adjusting valve. Thereby, the damping force of the extending | stretching side and contraction side can be adjusted by adjusting the flow resistance of a damping force adjustment valve.

However, in the conventional damping force adjustable hydraulic shock absorber, the stretching side of the piston rod, the oil flows through the common main passage in the same direction from the upper chamber to the reservoir side, so that the damping force is generated by the damping force adjusting valve. The damping force on the overshrinkage side has a constant relationship determined by the ratio of the hydraulic pressure area between the stretching side and the shrinkage side of the piston rod, and thus there is a problem that the degree of freedom in setting the damping force characteristics is limited.

In addition, since the hydraulic pressure area on the contraction side of the piston rod is small, when bubbles are generated in the cylinder, a large stroke is required to compress the bubbles, and there may be a delay in generating damping force therebetween.

This invention is made | formed in view of the point mentioned above, and an object of this invention is to provide the damping force adjustable hydraulic shock absorber which can raise the freedom degree of setting of damping force characteristics.

1 is a longitudinal cross-sectional view of a damping force adjustable hydraulic shock absorber according to one embodiment of the present invention.

2 is an enlarged view of the main part of the apparatus of FIG.

3 shows damping force characteristics of the device of FIG.

4 shows the damping force characteristics of the soft characteristics on the contracting side of the apparatus of FIG.

* Explanation of symbols for main parts of the drawings

1: damping force fixed hydraulic shock absorber 2: cylinder

2a: Cylinder upper chamber (1st chamber) 2b: Cylinder lower chamber (2nd chamber)

4: reservoir 5: piston

6: piston rod 11: oil furnace (first communication path)

12: disc valve (first check valve) 15: oil furnace (second communication passage)

16: check valve (second check valve) 17: damping force adjustment mechanism

40: fixed orifice A: pilot main attenuation valve

B: flow control valve (variable orifice)

In order to solve the above problems, the damping force adjustable hydraulic shock absorber according to claim 1 of the present invention is a cylinder in which an oil is enclosed, a reservoir in which an oil and a gas are enclosed, and is slidably fitted in the cylinder, thereby providing a first inside of the cylinder. A piston partitioning between the seal and the second chamber, a piston rod having one end connected to the piston and the other end passing through the first chamber and extending out of the cylinder, and installed in the piston to communicate between the first chamber and the second chamber. A first check valve installed in the first communication path and a first communication path allowing the flow of oil from the second chamber side to the first chamber side and generating a damping force, and communicating the second chamber with the reservoir. A second check valve installed at the second communication path, allowing a flow of oil from the reservoir side to the second chamber side only; a main passage communicating the first chamber with the reservoir; Passage And a damping force adjustment mechanism for controlling the flow of oil to generate a damping force and to adjust the damping force.

With such a configuration, the first check valve is closed when the piston rod is released and the oil in the first chamber is pressurized, and the first check valve is opened during the contraction stroke, and the second check valve is closed so that the piston Since the oil in the first chamber and the second chamber is pressurized as the rod penetrates into the cylinder, the oil flows through the main passage from the first chamber side to the reservoir side during the expansion and contraction, and generates a damping force by the damping force adjusting mechanism. At the same time adjust the damping force. In addition, during the shrinkage stroke, the damping force is also generated by the first check valve of the first communication path in addition to the damping force generated by the damping force adjusting mechanism.

In addition, the invention of claim 2, in addition to the configuration of claim 1, the damping force adjusting mechanism is characterized in that the valve is opened in accordance with the pressure of the oil in the main passage, and the damping force is generated in accordance with the opening degree. Therefore, a pilot main attenuation valve for adjusting the damping force, a secondary passage connected to the main passage to bypass the pilot main attenuation valve, and a fixed orifice arranged in series in the secondary passage And a variable orifice, wherein the pilot main attenuation valve obtains pilot pressure between the fixed orifice and the variable orifice of the sub-path.

In this way, during the expansion and contraction of the piston rod, the oil flows through the sub-path and the main path from the first chamber side to the reservoir, and directly adjusts the passage area of the sub-path by adjusting the passage area of the variable orifice. At the same time, the damping force characteristics can be adjusted by changing the pilot pressure of the pilot main attenuation valve.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of this invention is described in detail based on drawing.

As shown in FIG. 1 and FIG. 2, the damping force adjustable hydraulic shock absorber 1 of this embodiment has a double cylinder structure in which the outer cylinder 3 was provided in the outer side of the cylinder 2, and the cylinder 2 ) Is formed between the outer cylinder (3) and the outer cylinder (3). The piston 5 is slidably fitted in the cylinder 2, and this piston 5 allows the inside of the cylinder 2 to have a cylinder upper chamber 2a (first chamber) and a cylinder lower chamber 2b (second). It is divided into two rooms. One end of the piston rod 6 is connected to the piston 5 by a nut 7, and the other end of the piston rod 6 is connected to the cylinder 2 and the outer cylinder 3 via the upper cylinder chamber 2a. It is inserted through the rod guide 8 and the oil seal 9 mounted on the upper end and extends out of the cylinder 2. The lower end of the cylinder 2 is provided with a base valve 10 that partitions the cylinder lower chamber 2b and the reservoir 4. Oil (oil liquid) is sealed in the cylinder 2, and oil and gas of a predetermined pressure are sealed in the reservoir 4.

The piston (5) is disposed along its circumferential direction and is cylindrical A plurality of oil passages 11 (first communication passages) are provided to communicate between the lower chambers 2a and 2b. The piston 5 is closed against the flow of oil from the upper cylinder 2a of the oil passage 11 to the lower cylinder 2b of the oil passage 11 to prevent flow, while the upper cylinder 2b in the cylinder lower chamber 2b is closed. A disc valve 12 (first check valve) is provided which opens the valve with respect to the flow of oil to the side chamber 2a and generates a damping force according to the opening degree. The disc valve 12 has an annular valve sheet 13 protruding to the outer circumferential side of the opening of the oil passage 11 of the cross section of the piston 5, and an inner circumferential portion thereof clamped to the piston 5, and an outer circumferential portion thereof. Is composed of a plurality of disk-shaped valve main bodies 14 which are seated on the valve seat 13, and the valve main body 14 has a cylinder shape through an oil passage 11. An orifice 14a (notch) is formed to always communicate between the lower chambers 2a and 2b.

In addition, the base valve 10 has a cylinder at the oil passage 15 (second communication passage) for communicating the cylinder lower chamber 2b and the reservoir 4 with the reservoir 4 side of the oil passage 15. A check valve 16 (second check valve) is provided that allows only the flow of oil to the lower chamber 2b.

The damping force adjustment mechanism 17 is provided in the side part of the outer cylinder 3. The damping force adjusting mechanism 17 is fitted with the proportional solenoid 19 in the other end opening of the cylindrical case 18 in which one end opening is coupled to the side wall of the outer cylinder 3, and is turned and fixed by the retainer 20. It is. In the case 18, the other end part of the substantially cylindrical housing member 22 in which the one end side was narrowed and the small diameter opening part 22a was formed in the main-body member 21 of the proportional solenoid 19 is turned. An annular valve member 23 is fitted into the housing member 22. The valve member 23 divides the housing member 22 into two chambers, an oil chamber 22b and an oil chamber 22c. It is. The valve member 23 is provided to the holding member 24 by the nut 26 with the annular fixing member 25 which the holding member 24 is inserted and passed in and is arrange | positioned in the oil chamber 22c, The holding member 24 is screwed into the main body member 21 of the proportional solenoid 19 and fixed.

A tube 27 is fitted outside the cylinder 2, and an annular passage 28 is formed between the cylinder 2 and the tube 27. The annular passage 28 communicates with the cylinder upper chamber 2a by an oil passage 29 provided near the upper end of the side wall of the cylinder 2, and also has a housing in the opening 30 provided on the side wall of the tube 27. The small diameter opening part 22a of the member 22 fits and communicates with the oil chamber 22b.

The valve member 23 is provided with a plurality of oil passages 31 disposed along its circumferential direction and penetrating in the axial direction, and annular valve sheets 32 and 33 are respectively disposed around the plurality of oil passages 31. It protrudes by a predetermined | prescribed step | step. A negative disk valve 34 having an orifice 34a (cutout) is seated on the inner valve seat 32 having a small amount of protrusion.

An almost cylindrical movable member 35 is slidably fitted to the outer circumferential portion of the fixing member 25. The movable member 35 is seated on an outer valve seat 33 having a large protruding amount of the valve member 23 via an annular floating valve 36 at one end thereof, and has a disc shaped plate in a flange portion formed inside the one end thereof. The outer circumferential portion of the spring 37 abuts liquid-tightly and is pressed (loaded) in the valve closing direction, that is, the valve seat 33 side. An oil chamber 38 is formed between the valve member 23 and the leaf spring 37, and the back pressure chamber 39 is formed of the fixing member 25, the movable member 35, and the leaf spring 37. do. The leaf spring 37 is provided with a fixed orifice 40 (notched) for communicating the oil chamber 38 and the back pressure chamber 39.

Then, the pilot main attenuation valve A (hereinafter referred to as main attenuation valve A) is formed by the fixing member 25, the valve sheet 33, the movable member 35, the floating valve 36, and the leaf spring 37. The movable member 35, the floating valve 36, and the leaf spring 37 open the valve under the pressure of the oil chamber 38 side, generate | occur | produce the damping force according to the opening degree, and the back pressure chamber 39 The valve opening pressure is adjusted by acting in the valve closing direction as a pilot pressure. The oil chamber 38 communicates with the oil chamber 22c via the main attenuation valve A. The oil chamber 22c communicates with the annular oil passage 42 formed between the case 18 and the housing member 22 by an oil passage 41 provided on the side wall of the housing member 22. 42 is in communication with the reservoir 4. Moreover, the valve opening pressure of the sub disc valve 34 is set lower than the valve opening pressure of the main attenuation valve A. FIG.

A bore 43 is formed in the main body member 21 of the proportional solenoid 19, and the bore 43 communicates with the back pressure chamber 39 by an oil passage 44 provided in the holding member 24. . An annular groove 45 is formed on the inner circumferential surface of the bore 43, and the annular groove 45 is connected to the annular oil path 42 by the oil path 46. The spool 47 is slidably fitted in the bore 43. And the flow control valve B (variable orifice) is comprised by the bore 43 and the spool 47, and the spool 47 is the spring 49 in accordance with the energization current of the proportional solenoid 19 to the solenoid 48. FIG. The flow path area between the bore 43 and the oil passage 46 is adjusted by opening and closing the annular groove 45 while moving in response to the pressing force. The proportional solenoid 19 is provided with an adjustment screw 50 and a spring 51 for adjusting the initial load of the spring 49 onto the spool 47. In addition, in FIG. 2, the upper part of the spool 47 has shown the position which closed the flow path (hard side position), and the lower part showed the position which opens the flow path (soft side position).

In the above configuration, the oil furnace 29, the annular passage 28, the small-diameter opening 22a, the oil chamber 22b, the oil furnace 31, the oil chamber 38, the oil chamber 22c, the oil furnace (41) and the annular oil passage 42 constitute the main passage for communicating the cylinder upper chamber 2a and the reservoir 4, and the fixed orifice 40, the back pressure chamber 39, the oil passage ( 44, the bore 43, the annular groove 45, and the oil passage 46 constitute a negative passage for bypassing the main damping valve A.

The operation of the present embodiment configured as described above will be described next.

During the stretching stroke of the piston rod 6, the disk valve 12 of the piston 5 is closed in response to the movement of the piston 5 to pressurize the oil in the cylinder upper chamber 2a, and the oil passage 29, the annular Passes through the passage 28 and the small-diameter opening 22a and flows into the oil chamber 22b of the damping force adjusting mechanism 17, and further, the oil passage 31, the sub disc valve 34, the oil chamber 38, and the leaf spring. Reservoir through the fixed orifice 40, back pressure chamber 39, oil passage 44, bore 43, annular groove 45, oil passage 46 and annular oil passage 42 of 37. Flows to (4). At this time, when the pressure of the cylinder upper chamber 2a reaches the valve opening pressure of the main attenuation valve A, the main attenuation valve A is opened so that the oil flows from the oil chamber 38 to the oil chamber 22c, and further into the oil passage 41. And flows into the annular oil furnace 42. On the other hand, the oil as much as the piston 5 moved opens the check valve 16 of the base valve 10 from the reservoir 4, and flows to the cylinder lower chamber 2b.

Therefore, at the time of the extension stroke of the piston rod 6, the piston speed is slow and the flow path area of the orifice 34a, the sub-disk valve 34, the fixed orifice 40 and the flow control valve B before the valve opening of the main attenuation valve A is performed. This results in a damping force of the orifice characteristic (damping force is almost proportional to the square of the piston speed). At this time, the sub-disk valve 39 adds damping force characteristics of the valve characteristics (damping force is almost proportional to the piston speed) in the low speed region of the piston speed, thereby making it suitable for the low speed region from the extremely low speed region of the piston speed. Damping force can be obtained. When the piston speed increases and the pressure in the cylinder upper chamber 2a rises and the main damping valve A opens, a damping force of the valve characteristic is generated in accordance with the opening degree to suppress excessive rise of the damping force.

In this case, the smaller the flow area of the flow control valve B, the larger the pressure loss due to the larger flow pressure, and the higher the pressure in the upstream back pressure chamber 39. Therefore, the valve opening pressure of the main attenuation valve A is increased, and the flow control valve B is increased. The larger the flow path area is, the smaller the pressure loss due to the lower the pressure is, the lower the pressure in the back pressure chamber 39 on the upstream side. Thus, the valve opening pressure of the main damping valve A is lowered. Therefore, by changing the flow area of the flow control valve B by the energizing current to the solenoid 19, the orifice characteristics can be directly adjusted, and the valve characteristics can be adjusted by changing the pressure in the back pressure chamber 39. The damping force characteristics can be adjusted from the region to the high speed region.

In addition, at the time of the contraction stroke of the piston rod 6, with the movement of the piston 5, the check valve 16 of the base valve 10 is closed, and oil in the cylinder lower chamber 2b is released from the piston 5. The oil flows into the cylinder upper chamber 2a through the disk valve 12 of the cylinder, and as much oil as the piston rod 6 penetrates into the cylinder 2 is transferred from the cylinder upper chamber 2a to the same oil as in the stretching stroke. Flows to the reservoir (4) side through.

Therefore, as in the stretching stroke, the orifice characteristics are reduced by the flow path area of the orifice 34a, the sub disc valve 34, the fixed orifice 40 and the flow control valve B before the piston speed is slow and the valve opening of the main attenuation valve A is opened. When damping force occurs, the piston speed is increased, the pressure in the cylinder upper chamber 2a rises, and the main damping valve A is opened. According to the opening degree, damping force of the valve characteristic is generated to suppress excessive rise of the damping force.

By changing the flow area of the flow control valve B by the energizing current to the solenoid 19, the orifice characteristics can be directly adjusted, and the pressure of the back pressure chamber 39 can be changed to adjust the valve characteristics. The damping force characteristics can be adjusted from the low speed region to the high speed region.

In addition, since the oil of the cylinder lower chamber 2b flows to the cylinder upper chamber 2a through the disk valve 12 of the piston 5 at the time of a contraction stroke, it is made by the disk valve 12 which has the orifice 14a. The damping force of the orifice characteristic and the valve characteristic is added. Therefore, the damping force characteristic on the contraction side (particularly, when the flow path area of the flow control valve B is increased by the characteristics of the disk valve 12 (the flow path area of the orifice 14a and the valve opening property of the valve body 14, etc.) is increased. That is, since the setting value of the damping force characteristic at the time of a soft characteristic can be changed, the freedom degree of setting a damping force characteristic can be improved. Damping force characteristics of the damping force adjustable hydraulic shock absorber 1 are shown in FIG. The damping force characteristic at the time of the soft characteristic of the contraction side is the damping force characteristic ① having the bending point A by the disk valve 12 of the piston 5 and the bending point by the damping force adjusting mechanism 17 as shown in FIG. It is a damping force characteristic (3) which has bending points A and B which synthesize | combined the damping force characteristic (2) which has B.

Further, even when bubbles are generated in the cylinder 2, the damping force can be generated directly by the disk valve 12 together with the movement of the piston 5 in the cylinder 2, thereby preventing the delay of the damping force generation. Can be.

Moreover, at the time of the extension stroke of the piston rod 6, the pressurized oil of the cylinder upper chamber 2a passes through the orifice 14a provided in the valve main body 14 which comprises the disc valve 12, and the cylinder lower chamber Although it flows into (2b), this oil flow is a trace amount of the grade which does not affect the damping force which the damping force adjustment mechanism 17 generate | occur | produces. That is, the disc valve 12 has a function as a check valve.

As described in detail above, according to the damping force adjustable hydraulic shock absorber according to the invention of claim 1, during the stretching stroke of the piston rod, the first check valve is closed to pressurize the oil in the first chamber, As the first check valve is opened and the second check valve is closed and the piston rod penetrates into the cylinder, the oil in the first chamber and the second chamber is pressurized. After passing through the reservoir, the damping force is generated by the damping force adjusting mechanism and the damping force is adjusted. In addition, during the shrinkage stroke, the damping force is also generated by the first check valve of the first communication path in addition to the damping force generated by the damping force adjusting mechanism. As a result, since the set value of the damping force characteristic on the contraction side can be changed by the valve opening characteristic of the first check valve, the degree of freedom in setting the damping force characteristic can be increased.

Further, according to the damping force adjustable hydraulic shock absorber according to the invention of claim 2, the oil flows through the secondary passage and the main passage from the first chamber side to the reservoir at the time of the expansion and contraction of the piston rod, thereby reducing the passage area of the variable orifice. By adjusting, the damping force characteristic can be adjusted by changing the pilot pressure of a pilot main attenuation valve directly while adjusting the passage area of a side passage. As a result, the damping force characteristics can be adjusted from the low speed region of the piston rod to the high speed region.

Claims (2)

An oil-sealed cylinder (2), an oil and gas-sealed reservoir (4), and a slidably fit into the cylinder to partition the inside of the cylinder into a first chamber (2a) and a second chamber (2b). A piston 5, a piston rod 6 having one end connected to the piston and the other end extending out of the cylinder through the first chamber, and installed between the first chamber and the second chamber. A first check valve (12) communicating with the first check valve (12) installed in the first communication path and allowing flow of oil from the second chamber side to the first chamber side and generating a damping force; A second check valve (16) communicating with the second chamber and the reservoir, a second check valve (16) installed in the second communicating passage and allowing only oil to flow from the reservoir side to the second chamber side; Main passages 29, 28, 22a, 22b, 31, 38, 22c, 41, and 42 for communicating with the first chamber and the reservoir; Controlling the flow of work and possible to generate a damping force at the same time to adjust the damping force to the damping force adjustable hydraulic shock absorber comprising: a damping force adjusting mechanism (17). The main damping valve according to claim 1, wherein the damping force adjusting mechanism includes a pilot main damping valve which opens the valve in accordance with the pressure of the oil in the main passage, generates a damping force in accordance with the opening degree, and adjusts the damping force in accordance with the pilot pressure. A secondary passage bypassing the pilot main attenuation valve, the fixed orifice and a variable orifice disposed in series in the secondary passage, wherein the pilot main attenuation valve is fixed with the fixed orifice of the secondary passage. A damping force adjustable hydraulic shock absorber characterized by obtaining pilot pressure between orifices.