JP4761419B2 - gas spring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a gas spring.
[0002]
[Prior art]
For example, as a gas spring for assisting the opening operation of a hatch back door in a vehicle, various proposals have been made so far. Basically, as shown in FIG. The cylinder body 1 has a rod body 2 that is inserted into the cylinder body 1 so that the tip end side, which is the lower end side in the figure, can be projected and retracted and is used as the other member.
[0003]
The piston 3 is slidably accommodated in the cylinder body 1 while being connected to the tip portion which is the lower end portion in the figure of the rod body 2 and divides the rod side chamber R1 and the piston side chamber R2 in the cylinder body 1. And an annular space A defined by the retainer 4 and the seal 5 inside the open end 1a of the cylinder body 1.
[0004]
By the way, in this gas spring, gas is sealed in the cylinder body 1 under pressure, and the rod body from inside the cylinder body 1 due to the area difference between the rod side chamber R1 surface and the piston side chamber R2 surface of the piston 3 2 is biased in the protruding direction, that is, in the extending direction.
[0005]
In addition, the code | symbol 6 in a figure shows a bearing member, and the metal core 5a in the seal | sticker 5 is made to contact | abut to the bottom surface of this bearing member 6.
[0006]
Therefore, as shown in FIG. 4, when the hatch back door D in the vehicle is opened, the open state of the hatch back door D can be maintained by the gas spring, but in this state, the cylinder body 1 in the gas spring. Is the so-called inverted state in which the rod member 2 is the lower member and the lubricating oil accommodated therein is stored in the annular space A. Therefore, the seal 5 is inserted into the rod member under the oil film. 2 can be slidably contacted with the outer periphery.
[0007]
As a result, when the hatch back door D is closed, the seal 5 slides on the outer periphery of the rod body 2 while exhibiting a predetermined sealing function, and the gas spring smoothly contracts.
[0008]
[Problems to be solved by the invention]
However, in the above-described conventional gas spring, as shown in FIG. 4, when the hatchback door D is in a closed state, the cylinder body 1 is a lower member and the rod body 2 is an upper member. Therefore, the lubricating oil accommodated inside flows out of the annular space A, and the oil film is hardly formed on the outer periphery of the rod body 2.
[0009]
Then, looking at the actual condition that this type of gas spring is mounted on the vehicle, the hatch back door D is in a closed state, that is, the gas spring is longer than the time in which the hatch back door D is in an open state. In many cases, it is in a non-use state that is a contracted state.
[0010]
Therefore, the state in which it is difficult to form an oil film on the outer periphery of the rod body 2 described above becomes longer, and when the gas spring is extended and operated after the elapse of time, the seal 5 remains in a dry state and the outer periphery of the rod body 2 is slid. There is a fear that smooth extension operation cannot be expected.
[0011]
Not only is this state repeated, but the deterioration of the seal 5 is accelerated, and therefore gas leakage due to the deterioration of the seal 5 is invited, and the original function as a gas spring may not be exhibited. .
[0012]
The present invention was devised in view of the above-mentioned circumstances, and the object of the present invention is to ensure smooth expansion and contraction and prevent early deterioration of the seal. It is to provide a gas spring that is optimal to make possible.
[0013]
[Means for Solving the Problems]
In order to achieve the above-described object, the configuration of the present invention includes a cylinder body, a rod body inserted into the cylinder body so that the tip side can be projected and retracted, and a slide inside the cylinder body while being connected to the tip portion of the rod body. capable comprises a piston for partitioning the accommodated has been the rod-side chamber and the piston side chamber in the cylinder body, and an annular space defined by the inside retainer and seal the open end of the cylinder body, the hatchback door of the vehicle The gas spring for assisting the opening operation is characterized in that an impregnation member made of an open-cell urethane resin made of a polyether-based polyurethane resin in which an annular space is impregnated with a lubricating oil is housed.
[0015]
Incidentally, the impregnation member may be allowed to move freely in the annular space, and the retainer is formed in an arbitrary shape as long as it can prevent the piston from interfering with the impregnation member during the drawing operation. good.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiment. Even in the gas spring according to the present invention, as shown in FIG. 1, basically, the conventional gas shown in FIG. It has the same configuration as the spring.
[0017]
That is, a gas spring according to an embodiment of the present invention is connected to a cylinder body 1, a rod body 2 whose tip side is inserted into the cylinder body 1 so as to be able to protrude and retract, and a distal end portion of the rod body 2. However, the piston 3 that is slidably accommodated in the cylinder body 1 and divides the rod side chamber R1 and the piston side chamber R2 in the cylinder body 1, and the retainer 4 and the seal 5 inside the opening end of the cylinder body 1 And an annular space A defined to assist the opening operation of the hatch back door D in the vehicle.
In the present invention, the gas spring is characterized in that an impregnation member 7 made of an open-cell urethane resin made of a polyether-based polyurethane resin in which the annular space A is impregnated with lubricating oil is housed.
[0018]
That is, in the gas spring according to the present invention, the impregnated member for impregnating the lubricating oil in the annular space A (see FIG. 3) defined by the retainer 4 and the seal 5 inside the opening end 1a of the cylinder body 1 is provided. 7 is supposed to be stored.
[0019]
In the illustrated case, the impregnating member 7 is housed in a state of filling the annular space A without so-called gaps, and therefore, the inner periphery thereof is always in contact with the outer periphery of the rod body 2. Yes.
[0020]
Therefore, an oil film is always formed on the outer periphery of the rod body 2, and a situation where the seal 5 is in sliding contact with the outer periphery of the rod body 2 in a so-called dry state can be avoided in advance.
[0021]
By the way, as for the impregnating member 7, as a result, it suffices as long as it can be permanently impregnated with the lubricating oil. Therefore, from this point of view, any configuration may be set.
[0022]
Therefore, as a result of repeated experiments, the applicant of the present application should firstly assume that the impregnating member 7 is made of an open-cell urethane resin. Next, the open-cell urethane resin is, for example, a polyether-based polyurethane. It was assumed that it was made of a resin, and two results were obtained that were preferably made of a polyester polyurethane resin.
[0023]
When the open-cell urethane resin is made of a polyether-based polyurethane resin, it is a matter of course that the lubricating oil has good impregnation properties, but there is a situation where water accumulated inside for some reason touches the impregnation member 7. Even if it exists, since it is excellent in stability with respect to water, it is advantageous at the point which the impregnation member 7 does not become easily embrittled.
[0024]
Further, when the open-cell urethane resin is made of a polyester-based polyurethane resin, there is a risk of hydrolysis embrittlement in non-neutral water of PH, but it is advantageous in that an ideal impregnation state of lubricating oil can be realized. Become.
[0025]
And as a numerical value at this time, the result that the number of cells was 15-60 cells / inch and the hardness was 50-300 N was most preferable.
[0026]
That is, first, when the number of cells is less than 15, so-called space is reduced, and therefore the amount of impregnation of the lubricating oil is reduced.
[0027]
On the other hand, when the number of cells exceeds 60, so-called space is excessively increased. Therefore, the impregnation amount of the lubricating oil is also reduced due to a decrease in the function of retaining the oil.
[0028]
Next, as for the hardness, if this is less than 50, it will be too soft, and therefore the assemblability will deteriorate, and even if it is assembled, the end of the impregnated member 7 made of open-cell urethane resin is There is a risk of causing a situation in which the retainer 4 or the seal 5 is sandwiched between the inner periphery of the retainer 4 or the seal 5 and the outer periphery of the rod body 2.
[0029]
When the hardness exceeds 300, the whole becomes hard. When the impregnated member 7 made of open-cell urethane resin in this state is accommodated in the annular space A, it is thermally expanded on the outer periphery of the rod body 2. It tends to be in a state of being pressed and causes a problem of increasing the sliding resistance.
[0030]
Incidentally, the hardness N mentioned here means the load after compressing a test piece made of open cell urethane resin having a diameter of 20 cm and a thickness of 50 mm by 25% and leaving it to stand for 20 seconds.
[0031]
Therefore, in the gas spring formed as described above, an upright state in which the cylinder body 1 is a lower member and the rod body 2 is an upper member is extended for a long time from the attached state or the used state. Even if maintained, the impregnation member 7 having lubricating oil is formed as an oil chamber in the annular space A defined by the retainer 4 and the seal 5.
[0032]
Since this oil chamber is made of an open-cell urethane resin having excellent impregnation characteristics, an oil film is always formed on the outer periphery of the rod body 2, and the seal 5 is slid onto the outer periphery of the rod body 2 in a dry state. Stop touching.
[0033]
As described above, the smooth expansion and contraction operation of the gas spring is ensured and the early deterioration of the seal 5 is prevented, and the permanent use thereof becomes possible. In the present invention, the following proposal is also made.
[0034]
That is, with respect to the retainer 4, the retainer 4 is a gas spring in which the piston 3 is directly connected to the seal 5 in the conventional case and, in the present invention, directly to the impregnation member 7 when the gas spring is extended. It functions as a stopper that prevents interference.
[0035]
On the other hand, in the conventional example, if the annular space A defined between the retainer 4 and the seal 5 is tried in the oil chamber, the sliding between the inner periphery and the outer periphery of the rod body 2 is performed. It is advantageous that the contact length is as long as possible.
[0036]
However, in this invention, since the oil chamber is formed by housing the impregnated member 7 made of open cell urethane resin in the annular space A, the sliding contact length with the outer periphery of the rod body 2 is taken large. There is no need.
[0037]
As long as that is the case, in the present invention, the retainer 4 is not limited to fixing the impregnating member 7 in a predetermined place, but it is sufficient to exhibit the function of the stopper described above. Further, this may be formed by press molding. In this case, not only the retainer 4 is cost-effective but also the weight of the component is reduced as compared with the case where the retainer 4 is conventionally sintered or resin-formed. This is advantageous in that the weight of the gas spring can be reduced.
[0038]
Further, in view of the above, as shown by the broken line in FIG. 2, the retainer 4 is also press-molded so as to make the cross section inwardly concave, and the impregnation member that forms the oil chamber It is advantageous in that the retainer 4 and the impregnation member 7 can be assembled, that is, an oil chamber can be easily formed.
[0039]
【The invention's effect】
As described above, in the first aspect of the present invention, the cylinder body is used as the lower member and the rod body is used as the upper member, and the upright state is maintained for a long time from the mounted state or the used state. Even if it is done, it will be formed as an oil chamber having an impregnated member made of open-cell urethane resin made of polyether polyurethane resin impregnated with lubricating oil in the annular space defined by the retainer and the seal, As a result, an oil film is always formed on the outer periphery of the rod body with this impregnated member, and it is possible to avoid in advance the situation of sliding contact with the outer periphery of the rod body when the seal is dry.
[0040]
And since this impregnation member is formed with the open-cell urethane resin of the characteristic which is excellent in impregnation property, it becomes possible to always form an oil film on the outer periphery of a rod body with this impregnation member.
[0041]
In particular, in the present invention, since the polyether-based polyurethane resin is used as the open-cell urethane resin , the impregnation of the lubricating oil is of course good, but the water accumulated inside for some reason is impregnated in the impregnated member. Even if there is a touching situation, it is advantageous in that the impregnated member is not easily embrittled because of its excellent stability to water .
[0042]
As a result, according to the present invention, smooth expansion and contraction of the gas spring is ensured, and early deterioration of the seal is prevented, which is optimal for enabling its permanent use.
[Brief description of the drawings]
FIG. 1 is a front view of a gas spring according to the present invention, partially broken away.
FIG. 2 is a partial cross-sectional view showing an enlarged main part in many embodiments.
FIG. 3 is a view showing a gas spring as a conventional example similarly to FIG.
FIG. 4 is a schematic view showing one use state of a gas spring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder body 1a Open end 2 Rod body 3 Piston 4 Retainer 5 Seal 5a Core 6 Bearing member 7 Impregnation member A made of open cell urethane resin Annular space D Hatchback door R1 Rod side oil chamber R2 Piston side oil chamber

Claims (1)

A cylinder body, a rod body whose tip side is inserted into the cylinder body so as to be able to protrude and retract, and a rod side chamber and a piston side chamber which are slidably mounted in the cylinder body while being connected to the tip portion of the rod body. A gas spring that assists the opening operation of the hatch back door in the vehicle , and has a lubricating oil in the annular space. A gas spring comprising an impregnated member made of open-cell urethane resin made of a polyether polyurethane resin impregnated with

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