JPH028172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stay damper, and more particularly to a stay damper that has an increased repulsive force at an extended end and is suitable for use in an opening/closing device for a back door of an automobile.

This type of conventional stay damper is an all-gas chamber in which a gas chamber is divided into a cylinder via a piston, and gas is sealed in the gas chamber, and the piston rod is constantly urged in the direction of extension by the gas pressure in the gas chamber. The stay damper is interposed between, for example, the back door of a car and the body of the car via a bracket. When the back door key is removed, the stay damper extends and the back door opens. When closing, the back door is pushed in by hand to resist the repulsive force of the stay damper. It is known to compress the stay damper and close the back door. In addition, as another stay damper, an oil chamber is divided in the cylinder via a piston,
In addition, a gas chamber is divided on one side of the oil chamber via a free piston, oil is filled in the oil chamber, gas is filled in the gas chamber, and the piston rod is always moved in the direction of extension by the gas pressure in the gas chamber. It is known that this stay damper is interposed between the back door of an automobile and the vehicle body via a bracket.

The repulsive force F at the time of extension in the above-mentioned stay damper is considered as follows, ignoring the friction of the sliding part.
When the gas pressure at full extension is P ₀ Kgf/cm ² and the piston rod diameter is dcm, F=π/4d ² P ₀ Kgf ... [1].

However, when the sealed gas pressure is P, the gas temperature (absolute temperature) is T, the gas chamber volume is V, and the gas constant is R, PV=RT ∴P=R/VT ...[2].

That is, since the sealed gas pressure P varies depending on the temperature according to the relationship described in [2] above, the sealed gas pressure changes due to changes in the environmental temperature.

Since the sealed gas pressure changes according to the relationship shown in equation [2] above, the repulsive force F shown in equation [1] also changes accordingly. Generally, in order to prevent problems at low temperatures, a method is used to determine the gas pressure so as to maintain a minimum repulsion force even at low temperatures.
On the other hand, when the seat temperature is high, the repulsive force is too high, and for example, when the back door is extended to open, it suddenly stretches, and the push down when opening becomes large, resulting in poor operability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stay damper that increases the repulsive force only during extension and during a certain period from extension to start of compression.

In order to achieve this object, the present invention provides a stopper with a passage means on the cylinder side and a stopper with a check valve function to open and close this passage means in series, and the piston rod is fitted with a fixed stroke relative to the stopper. It is characterized by providing a matching expanded diameter portion.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a stay damper according to a preferred embodiment of the present invention. A piston rod 11 is slidably inserted into a cylinder 9 via a piston 10, and a gas chamber is partitioned into two oil chambers 12 and 13, which are upper and lower pressure chambers, by a piston 10 and a free piston. ing. A plurality of passages 14 are provided in the piston 10, and the passages 1
A valve 15 is provided at the side opening end of the oil chamber 12 of No. 4 so as to be openable and closable.
2 and 13 are designed to be opened and closed.

As is well known, a bushing 16, a main packing 17, and a stopper 18 are fixed to the inside of the cylinder by roll caulking 19, 20 or by press fitting, and the piston rod 11 is slidably inserted into these bushings 16, main packing 17, and stopper 18. has been done. Further, a spacer 24, which is an enlarged diameter portion having a taper 24a at the right end, is fitted on the outer periphery of the piston rod 11. The left end of the spacer 24 is bent and hooked onto the stepped portion 25 of the piston rod 11 and held by a retainer 26.
Furthermore, a rubber stopper 27 for extension and cutting is press-fitted in series at the left end of the stopper 18.

As shown in the figure, the outer diameter of the piston rod 11 may be made thicker in the portion corresponding to the spacer 24 without providing the spacer 24 as shown in the figure. In addition, this enlarged diameter portion fits into the stopper 18 when it is extended and cut as shown in the figure, and at this time, an oil chamber 12a is defined on the right side of the oil chamber 12 by the stopper 18.

The oil chambers 12 and 13 may be of an all-gas type used as a gas chamber.

Next, a communication hole 28 is formed in the stopper 18 as a passage means in the axial direction, and this communication hole 28 communicates the oil chamber 12a on the right side with the oil chamber 12. The surface is the communication hole 2
It is designed to close 8.

Next, the operation shown in FIG. 1 will be described.

When extending, for example, when opening the back door of a car and unlocking the back door, the piston 10 and piston rod 11 extend due to the gas pressure in the gas chamber, and the oil in one oil chamber 12 flows through the valve 15 and the passage 14 to the other. The oil flows out into the oil chamber 13 of the spacer 2, which is the expanded diameter part of the piston rod 11 at the time of full extension.
The outer periphery of 4 fits into the inner periphery of the stopper 18.

Also, during compression, for example, when closing the back door, the piston 10 and piston rod 11 are pushed against the gas pressure in the gas chamber, and at this time, the oil in the oil chamber 13 pushes open the valve 15 from the passage 14 and opens the other oil chamber 1.
2. However, when the lever starts compression, a negative pressure suction force is generated in the oil chamber 12a, and this suction force acts on the piston rod 11 in the direction of extension, so a large repulsive force is generated only from the end of extension to the beginning of compression. Become.

To explain this operation in more detail, during the above operation, in the left range where the spacer 24, which is the enlarged diameter part, does not fit into the stopper 18, the stopper 18 does not contact the piston rod 11, so the piston rod 1
1 reaction force is expressed by the above equation [1]. When the right end of the spacer 24 begins to fit into the stopper 18, the oil in the oil chamber 12a is compressed, passes through the communication hole 28, and pushes the rubber stopper 27 away. Escape to oil room 12. Therefore, the pressure in the oil chamber 12a increases only by the resistance of the communication hole 28 and the displacement resistance of the rubber stopper 27, and is almost the same as the pressure in the oil chamber 13. When it is near the maximum extension, retainer 2 on the piston side
6 begins to compress the rubber stopper 27, the communication hole 28 is closed by the rubber stopper 27, and the pressure in the oil chamber 12a increases. From this stage, oil escapes from the fitting portion between the stopper 18 and the spacer 24. That is, the compression stroke of the rubber stopper 27 becomes a kind of oil cushion. However, since the oil gradually escapes from the fitting portion, the pressure in the oil chamber 12a will not remain high for a long time.

On the other hand, when compressing from the above extended state, the oil chamber 12
a is filled with oil, and the communication hole 28 is connected to the rubber stopper 2.
Since the main gasket 17 is closed, the pressure in this area immediately drops below atmospheric pressure, resulting in a maximum negative pressure of about 0.3Kgf/cm ² , but the main gasket 17 is not able to suck in outside air. At this time, when the outer diameter of the spacer 24 is d ₂ , the reaction force F ₂ on the contraction side is limited to the section where the spacer 24 is fitted to the stopper 18 and is approximately F ₂ ≒π/4d ² ₂ P ₀ Since the temperature rises to Kgf, it is possible to prevent the door from falling at low temperatures.

In the compression stroke, the rubber stopper 27 and retainer 2
Even if 6 is separated, the pressure in the oil chamber 13 is higher than that in the oil chamber 12a, or in other words, the oil chamber 12a becomes negative pressure due to the retreat of the spacer 24, so the rubber stopper 27 continues to close the communication hole 28. Therefore, the effect of increasing the initial reaction force during compression can be maintained until the spacer 24 separates from the stopper 18.
Furthermore, when the reaction force is insufficient for extension at extremely low temperatures, use stopper 2.
Operation can be made more reliable by manually pushing and stretching only the fitting section between the spacer 8 and the spacer 24.

The extension-side repulsive force F ₁ and the compression-side repulsive force are specifically expressed in mathematical formulas as follows.

The repulsive force on the expansion side is F ₁ The repulsive force on the pressure side is F ₂ The sealing pressure is P ₀ The piston rod diameter is d ₁ The diameter of the spacer 24 (inflated diameter part) is d ₂ The pressure increase (change) in the gas chamber 12a is P When _{the c} -friction is f ₂ , the repulsive force on the extension side is F ₁ = π/4d ² ₁ P ₀ + π/4 (d ² ₂ − ^{d 2} ₁ ) P ₀
−π/4(d ² ₂ −d ² ₁ )(P ₀ +P _c )−f ₂ =π/4d ² ₁ P ₀ +π/4(d ² ₂ −d ² ₁ ){P
₀ −(P ₀ +P _c )}−f ₂ =π/4d ² ₁ P ₀ +π/4(d ² ₂ −d ² ₁ )(P
₀ −P ₀ −P _c )−f ₂ =π/4d ² ₁ P ₀ +π/4(d ² ₂ −d ² ₁ )(
−P _c )−f ₂ =π/4d ² ₁ P ₀ +π/4(d ² ₂ −d ² ₁ )P _c
-f ₂ ... [3] The numbers actually used in [3] formula P ₀ = 52Kg/cm ² P _c ≒3Kg/cm ² d ₁ = 1.0φ d ₂ =
Substituting 1.25φ, π/4d ² ₁ = 0.785 π/4d ² ₁ P ₀ = 40.82Kg d ² ₂ − d ² ₁ = 0.5625 π/4 (d ² ₂ − d ² ₁ ) = 0.4415625K
Since g π/4(d ² ₂ −d ² ₁ )P _c =1.3246875Kg, F ₁ =40.8−1.32−f ₂ Kg, and the reduction in repulsive force is as small as 1.32Kgf.

On the other hand, for the pressure side repulsive force, F ₂ = π/4d ² ₁ P ₀ + π/4 (d ² ₂ − ^{d 2} ₁ ) P ₀
−π/4(d ² ₂ −d ² ₁ )(−P _c ′+f ₂ =π/4d ² ₁ P ₀ +π/4(d ² ₂ −d ² ₁ )(P
₀ + P _c ) + f...[4], and substituting the above numbers into this, π/4 (d ² ₂ - d ² ₁ ) (P ₀ - P _c ) = 0.441562
5 x 55 = 24.285937 Therefore, F ₂ = 40.8 + 24.3 + f ₂ , and the repulsive force is 24.3
You can see that it is as large as Kgf.

FIG. 2 shows another embodiment of the present invention, in which a fitting gap 28a between a stopper 18a and a spacer 24 is used as a passage means, and a check valve is provided on the inner periphery of a rubber stopper 27a as an opening/closing member for this passage means. Similarly, FIG. 3 shows the rubber stopper 27a in FIG.
A core metal is built in to prevent deformation of the auxiliary lip 29.

In the case of FIGS. 2 and 3, when the pressure in the oil chamber 12a increases, the oil pushes open the lip 29 through the gap 28a and flows out into the oil chamber 12. Other functions and effects are the same as in the case of FIG.

As described above, according to the present invention, at the start of the compression stroke from the extension stroke, a negative pressure suction force is generated in the oil chamber 12a that is partitioned above the stoppers 18, 18a, and this suction force is applied to the piston rod 11. On the other hand, since it acts in the direction of extension, a large repulsive force is generated only at the time of extension and from the time of extension to the beginning of compression. Therefore, it is extremely effective if used to prevent doors from falling due to reduced repulsion due to low temperatures or gusts of wind.

Furthermore, according to the present invention, the expanded diameter portion of the piston rod only fits into the stopper 18, 27a in a narrow range near the extended end, and does not come into contact with the stopper in the other normal operating range, so no sliding friction occurs. The expansion and contraction strokes become smoother. The stoppers 18, 18a and the rubber stoppers 27, 27a are incorporated in place of the stoppers and rubber stoppers provided in the conventional stay damper, and since they are only provided with a passage means and a check valve function, there is no change in the basic length of the cylinder, and there is no change in the standard length of the cylinder. The stroke can be taken just as well as before.

[Brief explanation of drawings]

1, 2, and 3 are enlarged longitudinal sectional front views of main parts of a stay damper according to an embodiment of the present invention. 9...Cylinder, 10...Piston, 11...
Piston rod, 12, 13... Pressure chamber, 14...
...Passage, 15...Valve, 16...Button, 1
7... Main seal, 18, 18a... Stopper, 24... Spacer, 27, 27a... Stopper with check valve function, 28, 28a... Passage means, 29... Auxiliary lip.

Claims (1)

[Claims] 1. A piston rod is slidably inserted into a cylinder via a piston, two pressure chambers are defined within the cylinder by the piston, and the piston has a passage and a valve for opening and closing the two pressure chambers. The piston rod has a stay damper that is slidably penetrated through the bush and the main seal, and a stopper with a passage means in the cylinder and a stopper with a check valve function are installed in series. A stay damper that has an expanded diameter portion that fits into the stopper for a certain stroke. 2. The stay damper according to claim 1, wherein the expanded diameter portion comprises a spacer. 3. The stay damper according to claim 1, wherein the expanded diameter portion has a large diameter. 4 Claim 1 in which the passage means is a communicating hole
Stay damper as described in section. 5. The stay damper according to claim 1, wherein the passage means is a fitting gap. 6. The stay damper according to claim 1, wherein an auxiliary lip is provided on the stopper having a check valve function.