JP3813328B2 - Hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber that enables adjustment of the generated damping force, and more particularly, to an improvement of the hydraulic shock absorber that enables the adjustment of the generated damping force in response to the magnitude of the loaded load.
[0002]
[Prior art]
Among hydraulic shock absorbers that can adjust the level of generated damping force, for example, Japanese Patent Publication No. 2-41666 discloses a hydraulic buffer that can adjust the level of generated damping force in response to the magnitude of the load. Are disclosed.
[0003]
The hydraulic shock absorber disclosed in this publication is slidably accommodated in a cylinder, and the piston on the expansion side and the pressure side is divided into an upper oil chamber that is an extension side oil chamber and a lower oil chamber that is a pressure side oil chamber. Bypass passages each having a predetermined height, that is, a main damping valve that generates a high damping force, bypassing the main damping valve and communicating with the upper oil chamber and the lower oil chamber It is said that will be provided.
[0004]
In this bypass path, there is a so-called sub damping valve that generates a low damping force at a predetermined height on each of the expansion side and the compression side when oil passes. The opening end that opens to the lower oil chamber of the passage is opened and closed by a slider that is slidably interposed.
[0005]
In addition, when the relative position of the piston in the cylinder is close to the lower oil chamber, the slider is positioned in the lower oil chamber while the lower end is maintained in a fixed state, and the position at which the upper end faces the slider is detected. It is set to slide in the upward direction by a spring so as to close the open end of the bypass path.
[0006]
Therefore, according to the hydraulic shock absorber as the conventional proposal, when the hydraulic shock absorber is used, for example, as a suspension in a vehicle, the vehicle height becomes low due to a large load on the vehicle. In other words, the piston rod is inserted into the cylinder with a large stroke because a large load is applied to the piston rod that is connected to the lower end of the piston so that the piston rod can be inserted into and retracted from the cylinder. In some cases, the bypass path is blocked, and a so-called high damping force can be generated by the main damping valve.
[0007]
In contrast to the above, when the load on the vehicle decreases and the vehicle height returns to a high vehicle height, the bypass is opened and no high damping force is generated by the main damping valve. In other words, only a low damping force can be generated.
[0008]
As a result, according to this conventional hydraulic shock absorber, when the vehicle height tends to be low, a high damping force is generated to prevent bottoming in the running vehicle, and the vehicle height When the vehicle tends to have a high vehicle height, it is possible to give priority to the ride comfort in the running vehicle by generating a small damping force.
[0009]
[Problems to be solved by the invention]
However, in the hydraulic shock absorber disclosed in the above publication, there is a risk that it may be pointed out that the difference in level of damping force is not so large, and therefore there is a problem that effective damping force adjustment cannot be realized.
[0010]
That is, in the conventional hydraulic shock absorber described above, it is assumed that a part of the bypass path is configured in a piston nut formed in a bag shape, and that a sub damping valve is arranged in the piston nut. Yes.
[0011]
Therefore, the sub damping valve disposed in the piston nut tends to have a smaller diameter as a whole. Therefore, when the damping valve is formed of a leaf valve such as an annular shape, its rigidity is reduced. Will be higher.
[0012]
As a result, even if it is arranged as a sub damping valve and expects to generate a small damping force, in reality, a damping force that is not so small is generated, and this is generated by the main damping valve. When compared with the damping force, there is not much difference in height of the damping force.
[0013]
As a result, in the above-described conventional hydraulic shock absorber, when there is a large load and the vehicle height tends to be low, it is possible to prevent bottoming in the traveling vehicle by generating a high damping force. On the other hand, when there is no large load and the vehicle height tends to be high, it can be pointed out that the generation of low damping force cannot be expected and the ride comfort in the running vehicle cannot be improved. There will be fears.
[0014]
The present invention was devised in view of the above-described circumstances, and the object of the present invention is to enable adjustment of the generated damping force in response to the magnitude of the loaded load. It is to provide a hydraulic shock absorber that is optimized for use in a suspension in a vehicle, for example, by increasing the difference in height of the damping force that is applied.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the configuration of the present invention includes a damping valve that generates a damping force of a predetermined height on a piston that slides in a cylinder, while bypassing the damping valve. The cylinder has a bypass passage communicating with an upper oil chamber and a lower oil chamber defined by a piston, and a slider that is slidably disposed and opens and closes an opening end that opens to the lower oil chamber of the bypass passage. In the hydraulic shock absorber having a position detection spring which is disposed in the lower oil chamber while the lower end is maintained in a fixed state and the upper end is opposed to the slider, a bag-like shape constituting a part of the bypass path A check valve for preventing the flow of oil from the upper oil chamber side to the lower oil chamber side is disposed in the piston nut formed in the upper and lower sides of the check nut. In The upper and lower two-stage communication holes are opened on the outer periphery of the piston nut and are aimed at the through holes when the piston nut is lowered. When the relative position of the piston in the cylinder is close to the lower oil chamber, the upper end of the position detection spring is brought into contact with the slider and the slider is raised so that the slider moves upward. It is assumed that each through hole is blocked and the bypass path is blocked.
[0016]
At this time, it is preferable that each through-hole opened in the upper and lower stages of the piston nut is an orifice.
[0017]
More specifically, in the hydraulic shock absorber described above, an outer cylinder is disposed on the outer peripheral side of the cylinder, a reservoir chamber is formed between the cylinder and the outer cylinder, and a lower oil chamber in the cylinder is formed. It is assumed that a base valve is disposed in the lower oil chamber and the reservoir chamber is communicated with the reservoir chamber via the base valve.
[0018]
Further, in the hydraulic shock absorber described above, the slider is lowered when the tip of a biasing spring whose base end is locked to the piston side is in contact with the lower position detection spring, and the slider is lowered. Suppose that it is energized in the direction and stopped in a predetermined lowered state.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiment. As shown in FIG. 1, a hydraulic shock absorber according to an embodiment of the present invention includes a cylinder 1 as an axle side member, and the cylinder. 1 has an outer cylinder 2 that is disposed on the outer peripheral side and is also used as an axle side member, and is formed in a double cylinder type in which a space between the outer cylinder 2 and the cylinder 1 is set as a reservoir chamber R. It is said.
[0020]
The hydraulic shock absorber has a piston rod 3 which is a vehicle body side member and is inserted into the cylinder 1 so that the tip side, which is the lower end side in the figure, can protrude and retract, and the piston rod 3 is a suspension spring ( It is assumed that the hydraulic shock absorber 1 is urged in the extension direction by a suspension spring so as to protrude from the cylinder 1 with an urging force (not shown).
[0021]
The hydraulic shock absorber is connected to the lower end of the piston rod 3 and is slidably accommodated in the cylinder 1 so that the upper oil chamber R1 which is an extension side oil chamber and the lower side which is a pressure side oil chamber. The oil chamber R2 is partitioned, and the piston 4 is provided with damping valves 5 and 6 that generate predetermined damping heights, that is, high damping forces on the expansion side and the pressure side, respectively.
[0022]
Incidentally, each of the damping valves 5 and 6 is composed of a plurality of annular leaf valves each of which is laminated, and the damping valve 5 which is an extension side valve has an inner peripheral end as a fixed end and an outer peripheral end as a bending end. In this embodiment, the piston 4 is openably and closably opposed to the downstream end which is the lower end in the drawing of the open side port 4a, and the damping valve 6 which is a compression side valve has an inner peripheral end as a fixed end and an outer peripheral end. In an aspect in which the end is a bent end, the piston 4 is opposed to the downstream end which is the upper end in the drawing of the pressure side port (not shown) of the opening so as to be openable and closable.
[0023]
Further, a valve stopper 7 for restricting the amount of deflection of the damping valve 5 is arranged behind the damping valve 5 under the shim 5a. Then, it is supposed that the upper end which is the base end of the biasing spring 8 which will be described later is locked.
[0024]
A valve stopper 9 that regulates the amount of bending of the damping valve 6 is also arranged behind the damping valve 6 under the intervention of the shim 6a. In the form, a bypass path, which will be described later, is configured, and a lateral hole 9a is formed having an outer end opened to the upper oil chamber R1 and an inner end opened to the outer periphery of the lower end inlay portion 3a of the piston rod 3.
[0025]
The hydraulic shock absorber includes a base valve 10 disposed so as to partition a lower oil chamber R2 partitioned in the cylinder 1 and a reservoir chamber R outside the cylinder 1, and this base valve 10 allows oil to flow out from the lower oil chamber R2 to the reservoir chamber R and to allow oil from the reservoir chamber R to flow into the lower oil chamber R2.
[0026]
Incidentally, the base valve 10 is held on the inner bottom of the lower cap 11 that closes the lower end of the outer cylinder 2 and is disposed on the valve case 12 that is disposed so as to close the lower end of the cylinder 1. The pressure-side damping valve 13 that faces the port 12a and the suction valve 14 that also functions as a check valve that faces the suction port 12b on the outer circumferential side of the valve case 12 are provided.
[0027]
Then, the lower end of a position detection spring 16 described later is connected to a center rod 15 connected to the shaft core portion of the valve case 12 by caulking so as to be in a fixed state.
[0028]
In this embodiment, the compression side damping valve 13 in the base valve 10 is composed of a plurality of annular leaf valves stacked in the same manner as the damping valves 5 and 6 disposed on the piston 4, and has an inner peripheral end. Is fixed to the fixed end and the outer peripheral end is a bent end.
[0029]
In this embodiment, the suction valve 14 is composed of a single annular leaf valve and is set to a floating structure urged by a non-return spring 14a. However, the predetermined check action and suction action are guaranteed. As long as it is done, although not shown, the inner peripheral end may be a fixed end and the outer peripheral end may be a bent end.
[0030]
Therefore, in the hydraulic shock absorber according to this embodiment formed as described above, the oil from the upper oil chamber R1 is supplied during the expansion / contraction operation in which the piston rod 3 is retracted from the cylinder 1. The oil flows out to the lower oil chamber R2 through the expansion side damping valve 5, and the oil from the lower oil chamber R2 flows into the upper oil chamber R1 through the damping valve 6.
[0031]
At this time, excess oil corresponding to the intrusion volume of the piston rod 3 in the lower oil chamber R2 flows into the reservoir chamber R via the compression side damping valve 13 in the base valve 10, and the piston rod 3 The oil which becomes deficient in the lower oil chamber R2 corresponding to the withdrawal volume of the oil is replenished from the reservoir chamber R into the lower oil chamber R2 via the suction valve 14 in the base valve 10.
[0032]
Further, when oil passes through the damping valves 5, 6 and 14, a damping force having a predetermined height is generated. At this time, the hydraulic shock absorber 1 exhibits a so-called shock absorber function. It will be.
[0033]
By the way, the hydraulic shock absorber described above has a bypass path (not shown) that allows the upper oil chamber R1 and the lower oil chamber R2 to communicate with each other by bypassing the damping valves 5 and 6 disposed on the piston 4. At the same time, the slider 17 is provided to open and close the opening end opened to the lower oil chamber R2 of the bypass passage, and the upper end of the position detection spring 16 is opposed to the slider 17.
[0034]
To explain a little, first, the bypass path is in the illustrated embodiment, and a part of the bypass path is formed in a bag-shaped piston nut 18 screwed into the lower end inlay part 3a of the piston rod 3, that is, an empty part. The empty portion 18a has a check valve 19 to be described later.
[0035]
The piston nut 18 has through-holes 18b and 18c made up of upper and lower two-stage orifices that communicate the upstream side and the downstream side of the check valve 19 with the outer peripheral side of the piston nut 18, respectively. It is supposed to become.
[0036]
Of course, the through holes 18b and 18c constitute a bypass path. In this embodiment, each of the through holes 18b and 18c is set to be an orifice. The damping effect is exhibited.
[0037]
In addition, the bypass passage is formed in the shaft core portion of the lower end inlay portion 3a of the piston rod 3 and the lower end thereof is opened to the empty portion 18a, while communicating with the upper end of the through hole 3b. The valve stopper 9 is also configured to have a part of a lateral hole 3c communicating with the opened lateral hole 9a.
[0038]
Next, the slider 17 is interposed on the outer periphery of the piston nut 18 so as to be slidable in a direction coinciding with the sliding direction of the piston 4 in the vertical direction in the figure. Sometimes, the upper and lower two-stage communication holes 17a and 17b that are respectively aimed at the through holes 18b and 18c are opened.
[0039]
The slider 17 has a stepped portion 17c formed at the boundary between a small diameter portion (not shown) on the upper half side and a large diameter portion (not shown) on the lower half end side. The time when the slider 17 is lowered is set to be seated on the step 18d formed at the boundary between the small diameter portion (not shown) and the large diameter portion (not shown) of the piston nut 18.
[0040]
Incidentally, when the slider 17 is in the raised state shown in the drawing, an oil reservoir chamber r is formed between the step portion 17c of the slider 17 and the step portion 18d of the piston nut 18, and the oil in the oil reservoir chamber r is formed. Is set so as to allow the outflow to the outside by a so-called gap flow and not to flow out instantaneously.
[0041]
The lowered state of the slider 17 is realized when a position detection spring 16 to be described later is not in contact with the slider 17, and is realized by the biasing spring 8, that is, the base end as the upper end is extended. The lower end of the biasing spring 8 that is locked to the valve stopper 7 on the rear side of the damping valve 5 on the side is realized by coming into contact with the step portion 17c. At this time, the biasing spring 8 The oil in the oil reservoir chamber r is discharged to the outside by the urging force.
[0042]
Further, the position detection spring 16 is composed of a coil spring, and as described above, the lower end of the position detection spring 16 is connected to the center rod 15 of the base valve 10 so as to be fixed, but the upper end of the position detection spring 16 stands in the lower oil chamber R2. It is assumed that the upper end thereof is opposed to the slider 17, that is, the enlarged diameter portion (not shown) which is the outer peripheral side portion of the step portion 17 c formed on the slider 17.
[0043]
The position detection spring 16 is set so that its spring force is larger than the spring force of the biasing spring 8 located above the slider 17, and the upper end of the position detection spring 16 comes into contact with the slider 17. When the hydraulic shock absorber is compressed with a large stroke and the relative position of the piston 4 in the cylinder 1 approaches the lower oil chamber R2, the slider 17 is raised against the spring force of the biasing spring 8. Is set to get.
[0044]
When the upper end of the position detection spring 16 is brought into contact with the slider 17 and the slider 17 is raised, the communication hole 17a and the communication hole 18b, and the communication hole 17b and the communication hole 18c according to the degree of the rise. The communication area is gradually reduced and the communication is cut off when the slider 17 is raised to the maximum, that is, the bypass path is cut off.
[0045]
By the way, the check valve 19 is a valve seat member that is supported on the upper end of the bottom cap 20 that closes the lower end opening of the piston nut 18 and divides the inside of the piston nut 18, that is, the upstream and downstream sides of the empty portion 18a. 21 and a leaf valve 22 disposed on the upper end of the valve seat member 21 so as to be separable.
[0046]
The leaf valve 22 is opened in the shaft core portion of the valve seat member 21 and is adjacent to the upper and lower sides of the valve seat member 21, that is, the above-described through holes 21a that allow communication between the upstream side and the downstream side. The non-return spring 23 provided is closed from the upper end side so as to be openable and closable.
[0047]
The leaf valve 22 has an outer peripheral side that is sandwiched between the outer peripheral side of the valve seat member 21 and the inner peripheral side of the stepped portion 18d of the piston nut 18 from above. It is assumed that the cover cap 24 covered from the upstream side is floated together with the non-return spring 23.
[0048]
Of course, the cover cap 24 is provided with an opening 24 a for communicating the upstream side of the empty portion 18 a in the piston nut 18 with the cover cap 24.
[0049]
Therefore, in the check valve 19 formed as described above, even if the upstream side consisting of the hollow portion 18a in the piston nut 18 becomes the high pressure side, the oil from this upstream side flows to the downstream side that is the low pressure side. On the other hand, when the opposite downstream side becomes the high pressure side, the flow of oil from the downstream side to the upstream side which is the low pressure side is permitted.
[0050]
As a result, in the bypass passage having the check valve 19, when the slider 17 is in the lowered state and the bypass passage is open, the piston 4 rises in the cylinder 1 and the upper oil chamber R1. When the upstream side, which is the side, becomes the high pressure side, this high pressure is not released to the downstream side via the check valve 19, that is, the leaf valve 22, and conversely, the piston 4 descends in the cylinder 1 and lower oil When the downstream side corresponding to the chamber R2 side becomes the high pressure side, the high pressure is released to the upstream side through the check valve 19, that is, the leaf valve 22.
[0051]
Therefore, in the hydraulic shock absorber according to this embodiment formed as described above, when the piston rod 3 is largely immersed in the cylinder 1 due to the action of a large load, the inside of the cylinder 1 The relative position of the piston 4 is close to the lower oil chamber R2, and at this time, the slider 17 that is in sliding contact with the outer periphery of the piston nut 18 is slid in the upward direction by the position detection spring 16 that is in contact with the lower side, thereby 18 bypasses a bypass path that forms a part thereof, that is, a bypass path that bypasses the damping valves 5 and 6 disposed in the piston 4.
[0052]
As a result, at the time of expansion / contraction operation in this hydraulic shock absorber in a state where the bypass passage is blocked, as described above, the damping action by the respective damping valves 5 and 6 disposed in the piston 4 and the compression side damping valve 13 in the base valve. In other words, a high damping force is generated.
[0053]
During this expansion / contraction operation, even if the piston rod 3 may momentarily protrude from the cylinder 1 with a large stroke, that is, the upper end of the lower position detection spring 16 is separated from the slider 17 and the slider 17 is energized. Even when the spring 8 can be lowered, the oil reservoir chamber r is formed between the slider 17 and the piston nut 18, so that it is configured to generate a sliding resistance. At this time, there is no fear that the slider 17 will be momentarily lowered. Therefore, when the extension side operation is performed in a state where a high damping force is generated, there is a problem that the damping force instantaneously decreases. Can be avoided in advance.
[0054]
On the other hand, when the piston rod 3 tends to protrude from the cylinder 1 because the load on the hydraulic shock absorber is small, the relative position of the piston 4 in the cylinder 1 is closer to the upper oil chamber R2, and at this time The position detection spring 16 is released from contact with the slider 17 slidably in contact with the outer periphery of the piston nut 18 and is slid in the downward direction by the biasing force of the indicator spring 8 to open the bypass path. It will be.
[0055]
As a result, at the time of expansion / contraction operation in the hydraulic shock absorber in a state where the bypass passage is opened, the oil flow in the bypass passage is taken into consideration in addition to the oil flow in the respective damping valves 5, 6 and 13 described above. Will be.
[0056]
In other words, when the hydraulic shock absorber is extended on the bypass passage in the open state, the oil from the upper oil chamber R1 passes through the bypass passage, particularly on the upstream side of the check valve 19 disposed in the piston nut 18. It will flow out to the lower oil chamber R2.
[0057]
At this time, the oil flowing out from the hollow portion 18a in the piston nut 18 into the lower oil chamber R2 passes through the upper orifice 18b of the piston nut 18 so that a predetermined low extension side by the orifice 18b. The damping force is generated.
[0058]
At this time, the oil corresponding to the withdrawal volume of the piston rod 3 that is insufficient in the lower oil chamber R2 is supplied from the reservoir chamber R to the lower oil chamber R2 via the suction valve 14 in the base valve 10.
[0059]
Next, during the pressure side operation of the hydraulic shock absorber with the bypass path open, the oil from the lower oil chamber R2 passes through the bypass path, not via the pressure side damping valve 6 disposed in the piston 4. It will flow into the upper oil chamber R2 through the hollow portion 18a in the piston nut 18 that is formed.
[0060]
At this time, the oil from the lower oil chamber R2 flows into the downstream portion of the check valve 19 through two routes to the empty portion 18a, that is, the piston nut 18 through the lower orifice 18c of the opening. There are two routes: a flow that reaches the upstream side of the check valve 19 through the valve 19 and a flow that passes through the upper-stage orifice 18 b of the piston nut 18 and flows directly into the upstream side of the check valve 19. Will flow in.
[0061]
Then, since the oil passes from the orifices 18b and 18c in each route and the oil from the downstream side of the check valve 19 flows through the check valve 19, a predetermined amount by the orifices 18b and 18c and the check valve 19 is determined. A low damping force will be generated.
[0062]
At this time, since the check valve 19 according to this embodiment, that is, the leaf valve 22 is arranged under the floating structure, for example, in the proposal disclosed in Japanese Patent Publication No. 58-29416. Compared to the extension-side damping valve as the sub-valve, there is no risk of vibration caused by stick-slip when sliding, and this is advantageous in that the generated damping force is easily stabilized. .
[0063]
Further, at this time, an amount of oil corresponding to the intruding volume of the piston rod 3 surplus in the lower oil chamber R2 during the pressure side operation flows out into the reservoir chamber R through the pressure side damping valve 13 in the base valve 10. At this time, a predetermined damping force is generated by the compression side damping valve 13.
[0064]
【The invention's effect】
As described above, in the present invention, when the hydraulic shock absorber is used, for example, as a suspension in a vehicle, when the load on the vehicle increases and the vehicle height tends to be low, the cylinder The relative position of the piston in the interior is closer to the lower oil chamber, the bypass path that bypasses the damping valve located in the piston is blocked, and a high damping force is generated, and the load on the vehicle is reduced. When the vehicle tends to be taller, the relative position of the piston in the cylinder is closer to the upper oil chamber, and the bypass path is opened and a low damping force is generated. Therefore, when a low damping force is generated, the oil passes through a hole formed by an opening orifice in a piston nut formed in a bag shape that constitutes a part of this bypass passage. Therefore, for example, compared to the case where a so-called sub-valve consisting of a leaf valve is provided in the empty space in the bag-shaped piston nut, the generated damping force can be kept low, and the high damping force Thus, it is possible to take a large difference in height between a low damping force and a low damping force.
[0065]
Further, in this invention, the leaf valve that functions as a so-called sub-valve in which the check valve disposed in the empty space in the bag-shaped piston nut forming the bypass passage generates a predetermined low damping force is provided as a floating structure. Therefore, compared to, for example, an annular leaf valve that slides next to the shaft, there is no risk of vibration due to stick-slip, and there is no risk of abnormal noise. It is possible to expect the generation of a damping force.
[0066]
As a result, according to the present invention, when used for a suspension in a vehicle, the level difference of the damping force adjusted in response to the magnitude of the loaded load is increased. For example, when the vehicle height is lowered, the damping is high. In addition to preventing bottoming in the vehicle by the generation of force, there is an advantage that priority can be given while improving the riding comfort in the vehicle by generating a low damping force when the vehicle height increases.
[Brief description of the drawings]
FIG. 1 is a half vertical cross-sectional view of a hydraulic shock absorber according to an embodiment of the present invention, partially broken away.
[Explanation of symbols]
1 cylinder
2 outer cylinder
4 Piston
5,6 Damping valve
8 Biasing spring
13 Pressure-side damping valve constituting the base valve
14 Suction valve constituting the base valve
16 Position detection spring
17 Slider
17a, 17b communication hole
18 Piston nut
18a Empty part inside piston nut
18b, 18c Through hole consisting of orifice
19 Check valve
R Reservoir chamber
R1 Upper oil chamber
R2 Lower oil chamber

Claims (1)

An upper oil chamber and a lower oil chamber that have a damping valve that generates a damping force of a predetermined height on a piston that slides in the cylinder, and that are delimited by the piston in the cylinder by bypassing the damping valve And a slider that is slidably disposed and opens and closes an opening end that opens to the lower oil chamber of the bypass passage, and the lower oil is maintained while the lower end is maintained in a fixed state. In a hydraulic shock absorber having a position detection spring that is disposed in a chamber and has an upper end facing the slider, a lower oil chamber is formed from the upper oil chamber side into a piston nut formed in a bag shape that constitutes a part of the bypass path. A check valve is arranged to block the oil flow to the side, and the upstream and downstream sides of the check valve are arranged on the outer periphery of the piston nut through the piston nut. And a slider in which two upper and lower communication holes that are respectively aimed at the above-described through holes are slidably provided on the outer periphery of the piston nut. When the relative position of the piston in the interior is closer to the lower oil chamber, the upper end of the position detection spring is brought into contact with the slider, and the slider is lifted so as to close the through holes and block the bypass passage. Hydraulic shock absorber set

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