JPH0231042A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To convert the spring load depending of the amount of the extension and the contraction at the same stroke position by leading the excessive oil to one of two oil storage chambers a compression gas is sealed when a piston is operated in the compression side, and linking the both oil storage chambers to return the oil when the piston is operated in the extension side. CONSTITUTION:A compression gas is sealed in oil storage chambers 7 and 8, and a free piston (not shown) to separate the gas and the operation oil is provided. When a piston 2 is slided to the compression side, a spring 21 is bent, the oil in an oil chamber 5 flows to an oil chamber 4 from a valve 19, and moreover, a valve 12 opens a port 14 and closes a linking passage 9, the oil opens an attenuation valve 16 and flows in the oil storage chamber 7 compressing the gas in the oil storage chamber 7, and the load of the spring 21 increasing in a straight line and the load of the gas in the oil storage chamber 7 increasing in a curved line are summed up. When the piston 2 is returned, the pressure in the oil chamber 5 is reduced, the valve 12 closes the port 14 and opens the linking passage 9, the oil in the oil storage chamber 7 enters to the oil storage chamber 8 making the gas pressures in the both chambers equal, and the spring load is reduced gradually after increasing instantly. On the other hand, when the piston is stroked from the intermediate position to the compression side, the spring load is increased gradually from that point increasing the rate of increase gradually.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in hydraulic M components used in motorcycle rear cushion units and the like.

(Prior Art) As a motorcycle cushion unit, one equipped with an oil reservoir chamber filled with compressed gas is widely known in order to compensate for fluctuations in the amount of oil in the cylinder due to expansion and contraction. This compressed gas is compressed as the contraction of the cushion unit progresses, and the reaction unit is elastically supported in the direction of expansion by this gas spring and a suspension spring provided separately.

In this case, the spring load of the suspension spring increases linearly with the stroke, but the spring load of the gas spring exhibits a curved increasing characteristic with an increasing rate of increase in the latter half of the stroke, and these accounting factors are reflected in the reaction. This becomes the spring load of the unit.

(Problem to be solved by the invention) By the way, in order to prevent the piston from bottoming out when the reaction unit expands and contracts greatly, it is necessary to set the spring load near the maximum pressure position to be sufficiently large. If this is done, for example, if the rear cushion unit is balanced in a position that is biased towards the compression side due to an increase in running weight, the spring load will increase rapidly even with a slight contraction from the balanced position, so it will be difficult to avoid small shocks or Vibrations were absorbed and the ride quality sometimes felt stiff.

In view of the above problems, an object of the present invention is to provide a hydraulic shock absorber that can obtain different spring loads depending on the magnitude of expansion and contraction even at the same stroke position.

(Means for Achieving the Object) The present invention includes a piston housed in a cylinder filled with hydraulic oil, a piston rod connected to the piston that freely slides and protrudes from the cylinder, and In a hydraulic shock absorber equipped with an oil reservoir chamber for compensating for fluctuations in the amount of oil in the cylinder, first and second oil reservoir chambers are provided as the oil reservoir chambers, and are opened when the piston is operated on the pressure side to drain excess hydraulic oil from the cylinder. A valve that leads to the first oil reservoir chamber, and a valve that opens when the piston is operated on the extension side to communicate the first oil reservoir chamber and the second oil reservoir chamber and return the hydraulic oil to the cylinder. Compressed gas is sealed in each of the second oil reservoir chamber and the second oil reservoir chamber via a partition member.

(Function) When the piston operates on the pressure side, only the gas in the first oil reservoir chamber that receives the excess hydraulic oil of the cylinder is compressed, and a spring load due to this compressed gas acts on the piston. When the direction of operation of the piston changes to the extension side, this spring load immediately decreases because the first oil sump chamber, which has a high pressure, communicates with the second oil sump chamber, which remains at a low pressure. These oil reservoir chambers continue to be in communication until the piston again switches to compression side operation, and the spring load reduced by the reversal of the piston is further reduced as the hydraulic fluid returns to the cylinder due to the extension side operation of the piston. For this reason, the spring characteristics due to the compressed gas differ between the compression side operation and the expansion side operation, and even in the compression side operation, the spring characteristics
This differs depending on the starting position of the pressure side operation at which communication between the first oil reservoir chamber and the second oil reservoir chamber is cut off.

(Example) Embodiments of the present invention are shown in FIGS. 1 to 6.

In Fig. 1, 1 is a cylinder filled with hydraulic oil, 2 is a piston that is slidably housed in the cylinder 1, and 3 is a hollow piston rod that is connected to the piston 2 and projects freely from the cylinder 1. It is.

The inside of the cylinder 1 is defined by the piston 2 into an oil chamber 4 on the piston port/rad 3 side and an oil chamber 5 on the opposite side. Further, the hollow portion 3A of the piston rod 3 passes through the piston 2 and communicates with the oil chamber 5 at all times. The piston 2 is provided with one pressure side valve that allows hydraulic oil to flow from the oil chamber 5 to the oil chamber 4, and an expansion side valve 20 that allows the hydraulic oil to flow in the opposite direction.

A bracket 6 and a reservoir tank 22 are attached to the base end of the piston rod 3, and a suspension spring 21 is interposed between the reservoir tank 22 and a spring seat 23 fixed to the outer circumference of the cylinder 1.

A first oil reservoir chamber 7 and a second oil reservoir chamber 8 as shown in FIG. 2 are formed inside the reservoir tank 22 and communicate with the oil chamber 5 through the hollow portion 3A of the piston rod 3. Ru. A predetermined amount of compressed gas is sealed in each of these oil reservoir chambers 7 and 8, and free pistons 10 and 11 as partition members are housed in each of them to separate the compressed gas and hydraulic oil.

Further, a communication passage 9 that allows the hydraulic oil in the oil reservoir chambers 7 and 8 to communicate with each other is formed to pass through the base end of the hollow portion 3A in the transverse direction.

A valve 12 that communicates the oil chamber 5 with the first oil reservoir chamber 7 and blocks the communication path 9 at the same time is provided in the hollow portion 3A. This valve 12 is biased by a spring 13 from the base end side of the piston rod 3 toward the oil chamber 5, and when the pressure in the hollow portion 3A communicating with the oil chamber 5 is low, the hollow portion 3A opens as shown in FIG. While the boat 14 extending from the portion 3A to the first oil storage chamber 7 is closed, the communication path 9 penetrating the base end side of the hollow portion 3A is opened. Furthermore, in response to high pressure in the hollow portion 3A, as shown in FIG. 3, it retreats against the spring 13, opening the boat 14 and simultaneously blocking the communication path 9.

A predetermined resistance is provided between the boat 14 and the first oil reservoir chamber 7 against the inflow of hydraulic oil from the boat 14 into the oil reservoir chamber 7.
In addition, a pressure side damping valve 16 biased by a spring 15 is interposed to prevent the flow in the opposite direction.

Also, a boat 17 that communicates the second oil storage chamber 8 and the oil chamber 5 is provided.
opens at a position closer to the oil chamber 5 side than the valve 12 in the hollow portion 3A. This boat 17 is provided with a check valve 18 that allows hydraulic oil to flow only from the second oil reservoir chamber 8 toward the oil chamber 5 . The above connection relationship is shown in the circuit diagram of FIG.

Next, the effect will be explained.

In this reaction unit, when the piston 2 slides toward the pressure side, the suspension spring 21 is bent, and the high pressure in the contracting oil chamber 5 causes the valve 12 to retreat, opening the boat 14 and simultaneously blocking the communication path 9. The hydraulic oil in the oil chamber 5 flows into the expanding oil chamber 4 via the pressure side valve 19, and the hydraulic oil corresponding to the intrusion volume of the piston rod 3 flows into the boat 1.
4, the pressure side damping valve 16 is pushed open and the oil flows into the first oil reservoir chamber 7.

In this way, only the gas in the first oil reservoir chamber 7 is compressed during the pressure side stroke of the piston 2, so the spring load of the reaction unit is equal to the spring load of the suspension spring 21, which increases linearly with the stroke. , and the spring load of the gas spring of the first oil reservoir chamber 7, which increases in a curved manner. That is, as shown in FIG. 5, the piston 2 is at the most extended position X. As the spring slides from point A to point Xm, the spring load increases in a curve from point A to point B, increasing the rate of increase according to the stroke.

Note that the broken line (c) in the figure indicates the spring characteristics of the suspension spring 21.

When the piston 2 reverses to the extension side at XnA, the oil chamber 5
The pressure of the valve 1 is reduced, and the valve 1 is biased by the spring 13.
2 closes the boat 14 and at the same time opens the communication passage 9. As a result of 0 and 2, the hydraulic oil in the high-pressure first oil reservoir chamber 7 is transferred to the low-pressure second oil reservoir chamber 7.
The gas pressures in oil reservoir chambers 7 and 8 become equal, and the spring load instantly drops from point B to point 0 in the figure.

Since the communication passage 9 is open during the subsequent rebound stroke, the spring load of the reaction unit is equal to the spring load of the suspension spring 21 during the compression side operation, and the compressed gas in the oil reservoir chambers 7 and 8 that communicate with each other. This is the result of adding a spring load.

That is, as shown in (b) of the figure, along with the extension stroke, the stroke decreases with a gentler curve than during the compression side operation, and at the most extended position Xo, it returns to point A, which is the same as at the start of the compression...11 stroke.

Also, piston 2 is X. When stroking from an intermediate position between XII+ and D to do
Start increasing from the point and with the stroke (cl) of the figure
J: Shows increasing property. Similarly, when the compression stroke starts at X2 in the figure, the spring load starts to increase from point E, showing the increasing characteristic shown in (e).In this way, no matter where the compression stroke starts, The spring load starts to increase gradually from the starting position and increases the rate of increase in stages, so even if the balance position changes due to an increase or decrease in running weight, the ride comfort will not change greatly and will be less susceptible to vibrations and shocks. A stable and preferable absorption feeling can be obtained. on the other hand,
In response to a severe impact such as when the piston 2 makes a full stroke from near its most extended position, the spring load rapidly increases in the latter half of the compression stroke, so there is no fear that the piston 2 will bottom out. Furthermore, since the spring load decreases with the reversal from the compression side operation to the expansion side operation, the reaction after the compression side operation due to pushing up from the road surface, etc. is efficiently damped.

By the way, in the load characteristics shown in FIG. 5, the initial sealed gas pressures of the first oil reservoir chamber 7 and the second oil reservoir chamber 8 are set to be equal, but it is also possible to set these to different pressures. It is. Specifically, a free piston 10 is placed in the first oil reservoir chamber 7.
By providing a stopper 2/1 as shown in FIG. 2 that restricts sliding beyond a certain level, the gas pressure in the first oil reservoir chamber 7 at the most extended position can be controlled regardless of the communication of hydraulic oil through the communication passage 9. First, it can be maintained higher than the second oil reservoir chamber 8.

The load characteristics of the cushion unit in this case are shown in FIG. Under this setting, the X
When the free piston 10 comes into contact with the stopper 24 at c, the expansion of the compressed gas in the first oil reservoir chamber 7 is regulated.
In the subsequent displacement of the piston 2 toward the extension side, a spring load based on the gas pressure in the second oil reservoir chamber 8 that further reduces the pressure and the repulsive force of the suspension spring 21 acts on the reaction unit. Therefore, the spring load when extended to the most extended position X0 is lower than point A at the start of the compression stroke, as shown at point F in the figure. Similarly, when the pressure side stroke is started at Xl, which is closer to X0 than Xc, there is a difference between the gas pressure in the first oil reservoir chamber 7 and the gas pressure in the second oil reservoir chamber 8. As shown at points D and G, the spring load changes before and after the start of the compression stroke. In this way, by changing the initial pressure settings of the first oil reservoir chamber 7 and the second oil reservoir chamber 8, it is possible to further increase the difference in spring load between the compression side operation and the expansion side operation.

Note that the reservoir tank 22 that accommodates the first and second oil reservoir chambers 7 and 8 does not necessarily need to be provided at the base end of the piston rod 3, but may be provided separately from the reaction unit body and connected to the oil chamber via piping. It may be connected to 5.

<Effects of the Invention> As described above, the hydraulic f-Jjll'f device of the present invention includes a valve that guides excess hydraulic oil in the cylinder to the first oil reservoir chamber during compression side operation, and a valve that guides surplus hydraulic oil in the cylinder to the first oil reservoir chamber during compression side operation. It is equipped with a valve that communicates the oil reservoir chamber with the second oil reservoir chamber and returns hydraulic oil to the cylinder, and each oil reservoir chamber is filled with compressed gas through a partition member, so that when the piston is operated on the pressure side The spring load changes depending on whether the movement is on the compression side or during compression side operation, and the spring load gradually increases at the beginning of the stroke regardless of the starting position in compression side operation. It provides a favorable feeling of absorption against shock and impact. Furthermore, even with large expansion and contraction, the piston can be prevented from bottoming out due to the rapid increase in spring load in the latter half of the compression stroke. Furthermore, since the spring load is reduced at the same time as the compression side operation is reversed to the extension side operation, the reaction after contraction can also be efficiently damped.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a reaction unit showing an embodiment of the present invention, Fig. 2 is a horizontal sectional view of a reservoir tank showing the configuration of the first and second oil reservoir chambers, and Fig. 3 is a valve valve. A vertical cross-sectional view of the main part of the piston rod to explain the operating state of the
Figure 4 is the hydraulic concave I￥8 diagram, which explains the flow of hydraulic oil, and Figure 5.
6 are graphs showing the relationship between the displacement of the piston and the spring load of the cushion unit, respectively. 1... Cylinder, 2... Piston, 3... Piston rod, 3A... Hollow part, 4, 5... Oil chamber, 7...
・First oil reservoir chamber, 8... Second oil reservoir chamber, 9... Communication passage, 1o, 11... Free piston, 12... Valve, 16... Pressure side damping valve, 18 ...Check valve, 2
1... Suspension spring, 22... Reservoir tank.

Claims (1)

[Claims] A piston is housed in a cylinder filled with hydraulic oil, and a piston rod connected to the piston is allowed to slide freely and protrude from the cylinder, and is equipped with an oil sump chamber that compensates for fluctuations in the amount of oil in the cylinder due to displacement of the piston. In the hydraulic shock absorber, first and second oil reservoir chambers are provided as the oil reservoir chamber,
A valve that opens when the piston operates on the pressure side and guides excess hydraulic oil in the cylinder to the first oil reservoir chamber, and a valve that opens when the piston operates on the rebound side and connects the first oil reservoir chamber and the second oil reservoir chamber while the cylinder and a valve that recirculates the hydraulic oil.
and a second oil reservoir chamber, each of which is filled with compressed gas via a partition member.