JPH028171B2 - - 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.

As this type of conventional stay damper, those having the structures shown in FIGS. 1 and 2 are known.

The stay damper A shown in Fig. 1 is an all-gas chamber in which gas chambers 3 and 4 are divided into a cylinder 1 via a piston 2, and gas is sealed in the gas chambers 3 and 4. The piston rod 5 is always urged in the extension direction by pressure, and the stay damper A is interposed between, for example, the back door of an automobile and the vehicle body, and when the key of the back door is removed, the stay damper A is extended and the back door opens.
When closing, the back door is pushed in by hand to compress the stay damper A against the repulsive force of the stay damper and close the back door.

In addition, the stay damper B shown in FIG.
A gas chamber 1 is connected to one side via a free piston 11.
The oil chambers 8 and 9 are filled with oil, and the gas chamber 10 is filled with gas.
The piston rod 5 is always urged in the direction of extension by the gas pressure, and the stay damper B is interposed between the back door of the automobile and the vehicle body via brackets 6 and 7, as in the case of FIG. The opening and closing operations of the back door are the same as those shown in FIG.

The repulsive force F at the time of extension in the stay dampers A and B above is considered by ignoring the friction of the sliding part, and when the gas pressure at the time of 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, the gas pressure is determined so as to maintain a minimum repulsive force even at low temperatures.On the other hand, at high temperatures the repulsive force is too high, for example. When the back door is extended to open, it suddenly extends, making it difficult to push down when opening, resulting in poor operability.

Therefore, an object of the present invention is to provide a stay damper that increases the repulsive force only at the time of extension and during a certain period from the end of extension to the beginning of compression.

In order to achieve this object, the present invention provides a piston rod with a swollen diameter section near the piston, and also places an arbitrary interval in the cylinder in series with the main seal, so that when the piston rod is fully extended, the swelled diameter section of the piston rod only connects to the piston rod. It is characterized by the provision of an auxiliary gasket that fits.

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

FIG. 3 shows an all-gas type stay damper according to a preferred embodiment of the present invention. This means that the piston rod 1 is inserted into the cylinder 9 via the piston 10.
1 is slidably inserted into the cylinder 10, and the piston 10 partitions the cylinder 10 into, for example, two upper and lower pressure chambers, gas chambers 12 and 13. piston 10
A plurality of passages 14 are provided in the passageway 14, and a valve 15 is provided at the end of the passageway 14 on the gas chamber 12 side so as to be openable and closable.
3 is designed to be opened and closed.

As is well known, a bush 16, a main seal 17, and a stopper 18 are fixed to the inside of the cylinder by roll caulking 19, 20 or by press fitting, and these bushes 16, main seal 17, and stopper 18 are attached to the piston rod 1.
1 is slidably inserted.

In the present invention, the stopper 21 is arranged in series with the main packing 17 at an arbitrary interval, and the roll crimping 22 is connected to the stopper 21.
A U-shaped auxiliary packing 23, for example, is press-fitted in series on the right side of the stopper 21, and a spacer 24, which is an expanded diameter portion tapered at the left end, is fitted on the outer periphery of the piston rod 11. Spacer 2
The right end of the piston rod 4 is bent and hooked onto the stepped portion 25 of the piston rod 11, and is held by a retainer 26. A stopper 27 for extension and cutting is press-fitted in series at the right 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. Also, when this enlarged diameter portion is extended and cut as shown in the figure, it fits into the auxiliary packing 23, and at this time the gas chamber 1
2 is connected to two gas chambers 12 by an auxiliary gasket 23.
It is divided into a and 12b.

In FIG. 3, the stoppers 21 and 27 are not necessarily necessary, and it is sufficient that the auxiliary gasket 23 is held within the cylinder 9. An embodiment in which one of the stoppers 27 is omitted is shown in FIG. has been done. Therefore, the structure, operation, and effect of the embodiments shown in FIGS. 3 and 4 are substantially the same. Furthermore, gas chamber 12,
13 may be used as an oil chamber, and a gas chamber may be partitioned on one side of the chamber 13 via a free piston as shown in FIG. 2.

Next, the operations shown in Figures 1 and 2 will be described. During extension, 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 13, and the gas in one of the gas chambers 12 flows through the valve 15,
It flows out to the other gas chamber 13 through the passage 14, and when fully extended, the outer periphery of the spacer 24, which is the expanded diameter part of the piston rod 11, is connected to the stopper 21 and the auxiliary packing 2.
Insert into the inner circumference of 3.

Also, during compression, for example, when closing the back door, the piston 10 and piston rod 11 are moved to the gas chamber 13.
At this time, the gas in the gas chamber 13 pushes open the valve 15 through the passage 14 and flows out into the other gas chamber 12. However, when the lever starts compression, suction force as negative pressure is generated in the gas chamber 12a.
Since this suction force acts on the piston rod 11 in the direction of extension, a large repulsive force is generated only at the end of extension and from the end of extension to the beginning of compression.

To explain this operation in more detail, during the above operation, in the right side range where the spacer 24, which is the expanded diameter part, does not fit into the stopper 21 or the auxiliary packing 23,
Since the auxiliary packing 23 does not contact the piston rod 11, the reaction force of the piston rod 11 is expressed by the above formula [1]. However, when the left end of the spacer 24 starts to fit into the auxiliary packing 23, the auxiliary packing 23
The gas chamber 12 is divided into gas chambers 12a and 12b by being cut off by the inner periphery of the spacer 24 and the outer periphery of the spacer 24, and the gas in one gas chamber 12a is confined.
The gas pressure at a increases. However, the auxiliary patchkin 23
has a sealing property to the stopper 21 side, but not to the gas chamber 12b side, so the differential pressure between the gas chamber 12a and the gas chamber 12b on the extension side is about 3 kgf/cm ² . Since the normal sealing pressure is about 50 kgf/cm ² , the reduction in repulsive force due to this pressure is small and does not pose a major problem.

On the other hand, when compressing rather than expanding and cutting, the gas chamber 12a is filled with gas or oil, so the pressure in this area quickly drops below atmospheric pressure, resulting in a maximum negative pressure of about 0.3 kgf/ ^cm2 , but the main packing 17 However, it is not enough to draw in outside air. At this time, the reaction force on the contraction side F ₂
When the outer diameter of the spacer 24 is d ₂ , it rises to approximately F ₂ ≒π/4d ² ₂ P ₀ Kgf only in the section where the spacer 24 is fitted to the auxiliary packing 23, so at low temperatures etc. This can prevent the door from falling.

When the reaction force for stretching and cutting is insufficient at extremely low temperatures, the operation can be made more reliable by pushing only the fitted section of the auxiliary gasket 23 and the spacer 24 by hand to assist in stretching.

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 extension 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] [3] Substituting the numbers actually used, P ₀ = 52Kg/cm ² P _c ≒ 3Kg/cm ² d ₁ = 1.0φ d ₂ = 1.25φ, yields 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
g π/4(d ² ₂ − d ² ₁ )P _c = 1.3246875Kg Therefore, F ₁ = 40.8−1.32−f ₂ Kg, and the decrease in repulsive force is
It is small at 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 ) = 0.4415625×55 = 24.285937 Therefore, F ₂ = 40.8 +24.3+f ₂ , repulsive force is 24.3Kgf
It turns out that it is big.

In addition, as other embodiments of the present invention, the following configuration can also be used.

That is, in the embodiments shown in FIGS. 3 and 4, the auxiliary gasket 23 is attached to the stopper 21 which is caulked to the cylinder.
However, since the stopper 21 is merely an auxiliary member, it may be omitted. For example, as shown in FIG. 5, an auxiliary gasket 29 reinforced with a reinforcing metal fitting 28 is press-fitted into the cylinder 9 from the upper end, and after positioning, it is caulked. It may be arranged to prevent upward movement. The main purpose of the auxiliary gasket is to seal in the Y direction, and the smaller the sealing performance in the X direction, the better.As long as the seal satisfies this performance, the shape does not need to be limited to a U-shape.

Furthermore, as shown in FIG. 6, the auxiliary gasket 23 includes a core metal 32, and the stoppers 18, 21, the stopper 27, and the auxiliary gasket 23 shown in FIGS. 3 and 4 are used.
It is also possible to use a cushion rubber 30 that is integrated with a seal lip 31 that serves as an auxiliary packing.

According to the present invention, there are the following effects.

At the start of compression, which is the transition from full extension to the compression stroke, a suction force in the form of negative pressure is generated, and this suction force acts on the piston rod in the direction of extension, resulting in a large repulsion only during full extension and from full extension to the start of compression. force is generated. For this reason, the repulsion force decreases at low temperatures, etc.
It is also extremely effective if used to prevent doors from falling due to gusts of wind, etc.

Furthermore, the auxiliary packing comes into contact with the piston rod only when the expanded diameter part of the piston rod is fitted during full extension, and there is no sliding friction resistance between the auxiliary packing and the piston rod in the other stroke ranges of the piston rod. Good operability of expansion and contraction.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional front views of a conventional stay damper, and FIGS. 3, 4, 5, and 6 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, 1
5... Valve, 16... Bush, 17... Main seal, 23... Auxiliary packing, 24... Spacer, 21
...Stotsupa.

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. In the stay damper, the piston rod slidably passes through the bush and the main seal, a bulge is provided in the piston rod at a position near the piston, and the piston rod is arranged in series with the main seal at an arbitrary interval, A stay damper characterized in that an auxiliary packing is provided that fits only with the expanded diameter portion of the piston rod when the piston rod is fully extended. 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. The stay damper according to claim 1, wherein the auxiliary gasket is a U-shaped gasket. 5. The stay damper according to claim 1, wherein the auxiliary packing is press-fitted into the cylinder and is held on one side by a stopper.