JP2000145860A - Gas spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gap spring of small size with the overall height suppressed while the capacity of a gas working chamber is well secured, with certainly lubricated sliding parts between a piston member and cylinder body and having enhanced gas seal performance. SOLUTION: This gas spring comprises a cylinder body 2, piston member 3, gas working chamber 4 and a compression gas G put fully in the chamber 4, wherein the cylinder body 2 is configured so that approx. two thirds of its lower part has a cylinder forming member 6 in sleeve shape, and a first gas working chamber expansion part 7 in ring shape is formed in a part inside the cylinder body 2 and outside the cylinder forming member 6. A second gas working chamber expansion part 8 is formed inside the piston member 3, and a ring-shaped communication hole 9 is formed at the bottom of the cylinder forming member 6. If necessary, an oil accommodation part is formed at the top of the cylinder forming member 6 to supply oil to the wall surface of the cylinder hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas spring suitable for applying a cushion force to a mold of a press device or displacing the mold.

[0002]

2. Description of the Related Art A gas spring includes a cylinder body,
It has a piston member, and a compressed gas (for example, compressed nitrogen gas) filled in a gas working chamber defined by the cylinder body and the piston member to urge the piston member in the advance direction. The piston member includes a piston portion and a rod portion having a smaller diameter than the piston portion (normal type piston member),
A rod-shaped member (rod-type piston member) in which the rod portion functions as a piston portion, or the like is applied. In a gas spring using a normal piston member, the piston is slidably mounted in the cylinder hole of the cylinder body, and the outer periphery of the piston is annularly filled with packing and oil to seal compressed gas. Fiber material etc. are installed.

As shown in FIGS. 5 and 6, a gas spring 100 using a rod-type piston member includes a cylinder body 101, a piston member 104 movably mounted on the cylinder body 101, a cylinder body 101 and a piston member. And a compressed gas filled in the gas working chamber 103. The cylinder main body 101 includes a cylindrical lower casing 101a, an upper casing 101b, and a rod hole forming member 101c that is fitted inside the upper casing 101b and fixed by a retaining ring 102. In the lower casing 101a,
A gas filling valve mechanism 105 for filling the gas working chamber 103 with a compressed gas is mounted. Upper casing 10
1b, the rod hole forming member 101c is formed to have a long length in order to prevent the eccentric operation of the piston member 104 with respect to the cylinder body 101 to enhance the guideability of the piston member 104 and to prevent the leakage of the compressed gas. 1
04 has a longer support length.

A plurality of annular seal grooves are formed on the inner peripheral surface of the rod hole forming member 101c, and an annular seal member 106 is mounted on each of the annular seal grooves. The annular seal member 106 prevents dust, foreign matter, and the like adhering to the rod portion of the piston member 104 from entering the gas working chamber 103 and prevents the compressed gas in the gas working chamber 103 from leaking.

[0005] Here, since dust and foreign matter adhering to the rod portion of the piston member 104 enter the rod insertion hole of the rod hole forming member, the sliding portion and the annular seal member 106 are moved by the movement of the piston member 104. As a result, the sealing function of these annular seal members 106 is reduced, and the compressed gas leaks easily. It should be noted that as the volume of the gas working chamber 103 is larger, the pressure drop due to the leak of the compressed gas is less likely to occur, and the operability of the gas spring is easily maintained. Therefore, it is desirable to form the gas working chamber so that its volume is as large as possible. When the gas pressure of the compressed gas decreases, the press device is stopped, and the compressed gas is replenished from the valve mechanism 105 to the gas working chamber.

FIG. 7 shows a practical example of a gas spring 107 in which the volume of a gas working chamber is enlarged. The gas spring 107 is connected to the cylinder body 10
8, a piston member 109 movably mounted in a cylinder hole 108a of the cylinder body 108, and a piston member 10
9 and a gas working chamber 11 defined by a cylinder body 108
0 and the piston member 10 filled in the gas working chamber 110
9 for urging the gas to the advancing side. A gas filling valve mechanism 111 for filling compressed gas is mounted on a bottom wall portion of the cylinder body 108 facing the piston member 109. In the gas spring 107, the volume of the gas working chamber is expanded by extending the cylinder body downward and the gas working chamber downward.

On the other hand, there has been proposed a technique for improving the lubricating performance of a gas spring to suppress wear of a sliding portion between a piston member and a cylinder body and a seal member. For example,
In the die cylinder (gas spring) of U.S. Pat. No. 4,691,902, the cylinder body is disposed in a vertical posture,
The rod portion of the normal type piston member extends upward through the rod insertion hole in the upper end wall of the cylinder body, and the piston portion is slidably inserted into the cylinder hole. A reservoir for compressed gas is formed on the outside of the oil reservoir, an oil reservoir for storing oil is formed at a lower portion of the gas working chamber, and a riser pipe leading to an oil inlet at the bottom of the oil reservoir is extended into the reservoir. . When the piston member moves in and out, the oil in the oil reservoir is pushed up into the riser pipe, and when the piston member advances and moves, the mist of the oil and the compressed gas in the riser pipe is injected into the cylinder hole from the oil inlet into the cylinder hole. Then, it adheres to the peripheral surface of the cylinder hole to lubricate the sliding portion.

[0008]

According to the gas spring 100, the length of the rod insertion hole for holding the rod portion must be increased in order to ensure the guideability for guiding the piston member 104. The height of the cylinder body 101 is increased by the length of the hole forming member 101c. Moreover, since the gas working chamber is expanded downward to increase the volume of the gas working chamber, the height of the cylinder body 101 is further increased.

On the other hand, in the gas spring 107,
As in the case of the gas spring 100, the height of the cylinder body 101 increases because the gas working chamber is expanded downward to increase the volume of the gas working chamber. For this reason, it is difficult to reduce the overall height of the gas spring, and there is a problem that space is restricted in use and lacks versatility.

In the die cylinder of the United States patent, a rising pipe for filling a compressed gas is mounted so as to protrude from the bottom of the cylinder hole toward the piston member side. The cylinder cannot be stroked to the maximum, and the overall height of the cylinder body increases. In addition, since the oil in the start-up pipe is supplied into the cylinder hole by negative pressure, when the advance speed of the piston member is low, the suction speed of the oil and the compressed gas is reduced, and the peripheral surface of the cylinder hole is reliably secured. It cannot always be lubricated.
An object of the present invention is to reduce the overall height of a gas spring to reduce its size, to improve lubrication performance for lubricating a sliding portion between a piston member and a cylinder body, and the like.

[0011]

According to a first aspect of the present invention, a gas spring includes a cylinder body, a piston member movably mounted in a cylinder hole of the cylinder body, and a gas defined by the piston member and the cylinder body. In a gas spring including an operating chamber and a compressed gas filled in the gas operating chamber and biasing a piston member toward an advance side, the cylinder main body is a cylinder forming member forming a cylinder hole, and is a separate body. A first gas working chamber expansion part which forms a part of the gas working chamber inside the cylinder body and outside the cylinder forming member is formed. A second gas working chamber extension part forming a part of the gas working chamber is formed inside the piston member.

With the compressed gas filled in the gas working chamber,
The piston member is urged toward the advance side with respect to the cylinder body, and functions as a gas spring. When a large load is applied to the piston member against the gas pressure of the compressed gas, the piston member retreats with respect to the cylinder body (that is, the cylinder forming member). At this time, since the annular first gas working chamber expansion part and the second gas working chamber expansion part form a part of the gas working chamber, the compressed gas has a sufficient capacity in terms of capacity. And the gas spring is not easily affected, and the operability of the gas spring is easily maintained satisfactorily. The first gas working chamber expansion portion is formed inside the cylinder body and outside the cylinder forming member, and the second gas working chamber expansion portion is formed inside the piston member, so that the capacity of the gas working chamber is expanded. Thus, the overall height of the gas spring can be kept low, and the size can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the first gas working chamber extension portion is provided in the gas working chamber portion in the cylinder hole through an annular communication hole communicating with a lower end portion of the cylinder hole. It is characterized by being communicated with. Therefore, the flow resistance of the gas between the first gas working chamber expansion portion and the gas working chamber portion in the cylinder hole can be reduced.

According to a third aspect of the present invention, in the second aspect of the invention, when the piston member is at the stroke end in the retreating direction, the inner end of the piston member abuts or approaches the bottom surface of the cylinder hole. It is characterized by the following. Since the height of the cylinder body can be kept low, the overall height of the gas spring can be kept low and the size can be reduced.

According to a fourth aspect of the present invention, there is provided the gas spring according to the third aspect of the present invention, wherein a bottom wall of the cylinder body facing the piston member has a gas filling reverse for filling the gas working chamber with a compressed gas. The stop valve is mounted so as to protrude toward the piston member from the bottom surface of the cylinder hole. The compressed gas can be filled from the check valve for gas filling at the time of the first gas filling or when the compressed gas in the gas working chamber has decreased to some extent due to the leak of the compressed gas. Since the gas filling check valve is located in the second gas working chamber expansion portion of the piston member when the piston member is at the stroke end in the retreating direction, the gas filling check valve and the piston member interfere with each other. Nothing. Therefore, the height of the cylinder body can be kept low, and the overall height of the gas spring can be kept low, thus achieving downsizing.

[0016] The gas spring according to claim 5 is the gas spring according to claim 2.
4. The invention according to claim 4, wherein an annular oil storage portion is formed inside the piston member advancing end of the cylinder forming member, and the oil storage portion is filled with lubricating oil. The lubricating oil of the portion can be supplied to the peripheral surface of the cylinder hole. Since the lubricating oil is uniformly and stably supplied from the oil storage portion to the peripheral surface of the cylinder hole, the sliding portion between the piston member and the cylinder body can be reliably lubricated. as a result,
It is possible to suppress wear of the sliding portion and the seal member, suppress leakage of compressed gas, and ensure durability.

A gas spring according to a sixth aspect of the present invention is the gas spring according to the fifth aspect, wherein the cylinder forming member is provided with an oil supply portion for supplying lubricating oil to the oil storage portion. . Since the oil supply section is formed in the cylinder forming member, lubricating oil can be supplied to the oil storage section, and mounting and repair of the oil supply section are simplified.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2,
The gas spring 1 is suitable for, for example, applying a cushioning force to a mold of a press device or displacing the mold, and includes a cylinder body 2, a piston member 3, and the piston member 3 and the cylinder body. 2 and a compressed gas G (for example, a high-pressure compressed nitrogen gas) filled in the gas working chamber 4 to urge the piston member 3 toward the advance side.

The cylinder body 2 has a cylinder forming member 6 whose lower part is formed in a sleeve shape at about 2/3 of its lower part.
The cylinder forming member 6 has a cylinder hole 6a. The cylinder forming member 6 is formed separately from the cylinder main body 2 and is provided with four retaining rings 5 divided into four parts around the circumference of the cylinder main body 2.
It is fixedly installed inside. An annular first gas working chamber extension 7 is formed inside the cylinder body 2 and outside the cylinder forming member 6, and a second gas working chamber extension 8 is formed inside the piston member 3. . The first gas working chamber extension 7 and the second gas working chamber extension 8 form a part of the gas working chamber 4.

An annular communication hole 9 communicating with the outer peripheral portion of the lower end of the cylinder hole 6a is formed, and the first gas working chamber expansion portion 7 is connected to the gas working chamber portion 10 in the cylinder hole through the communication hole 9. Are in communication. Accordingly, the gas working chamber 4 includes the gas working chamber portion 10 in the cylinder hole, the first gas working chamber extension 7, the second gas working chamber extension 8, and the communication hole 9. By the way, the piston member 3 is configured such that its inner end 3a abuts or approaches the bottom surface of the cylinder hole 6a at the time of the stroke end in the retreating direction. A gas filling check valve 11 for filling the gas working chamber 4 with the compressed gas G is provided on a bottom wall portion 2a of the cylinder body 2 facing the piston member 3, and a piston member is disposed between the bottom of the cylinder hole 6a and the piston member. It is mounted so as to protrude to the third side.

The cylinder body 2 has a cylinder body 2
An annular seal groove 2b is formed at a location (the inner peripheral surface below the location where the retaining ring 5 is provided) where the annular seal member 12 is fixed to the cylinder forming member 6, and the annular seal member 12 is accommodated in the seal groove 2b. An annular dust seal member 13 is attached to the inner peripheral portion of the upper end portion of the cylinder forming member 6, and the piston member 3
An annular seal member 14 and the like are mounted on the outer peripheral portion of the piston portion. The seal members 12, 13, 14 maintain airtightness in the gas working chamber 4 and adhere to the piston member by the dust seal member 13. This prevents dust and foreign matter from entering the sliding portion between the piston member 3 and the cylinder forming member 6.

Next, the operation of the gas spring 1 will be described. By the compressed gas G filled in the gas working chamber 4,
The piston member 3 is urged toward the advance side with respect to the cylinder body 2 and functions as a gas spring. When a large load is applied to the piston member 3 against the gas pressure of the compressed gas G, the piston member 3 retreats with respect to the cylinder body 2, that is, the cylinder forming member 6. At this time, since the annular first gas working chamber expansion portion 7 and the second gas working chamber expansion portion 8 form a part of the gas working chamber 4, the compressed gas G has a sufficient capacity capacity, so that the compressed gas G The gas spring 1 is hardly affected by the leakage of G and the operability of the gas spring 1 is easily maintained satisfactorily.

When the gas pressure of the compressed gas G falls below the set value, the compressed gas G is again supplied from the gas filling check valve 11 to the gas working chamber 4 without applying a load to the piston member 3. Fill. The gas filling check valve 11 is located in the second gas working chamber extension 8 of the piston member 3 when the piston member 3 is at the stroke end in the retreating direction.
The gas filling check valve 11 and the piston member 3 do not interfere with each other. Therefore, the height of the cylinder main body 2 can be kept low, and the overall height of the gas spring 1 can be kept low, and the size can be reduced.

The first gas working chamber extension 7 is formed inside the cylinder body 2 and outside the cylinder forming member 6, and the second gas working chamber extension 8 is formed inside the piston member 3. In addition, the overall height of the gas spring 1 can be reduced while the capacity of the gas working chamber 4 is expanded, and the size can be reduced. Therefore, the gas spring 1 is easily applied in terms of space, and the versatility of the gas spring 1 is improved.

The first gas working chamber expansion portion 7 has a cylinder bore 6
Since the compressed gas G flows through the annular communication hole 9 when the piston member 3 advances and retreats, the compressed gas G flows through the annular communication hole 9 communicating with the lower end of the cylinder a. The flow resistance of the compressed gas G is reduced. Since the piston member 3 is supported by the cylinder main body 2 at two positions above and below the rod portion and the piston portion, the piston member 3 does not easily perform eccentric operation with respect to the cylinder main body 2 and operates stably. When the piston member 3 is at the stroke end in the retreating direction, the inner end 3a of the piston member 3 abuts on or approaches the bottom surface of the cylinder hole 6a. Therefore, the overall height of the gas spring 1 can be kept low and the size can be reduced.

Next, a modified embodiment in which the gas spring 1 is partially modified will be described. However, the same members as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIGS. 3 and 4, the cylinder body 15 of the gas spring 1 </ b> B has a cylinder forming member 16 in which about 2/3 of the lower portion is formed in a sleeve shape.
Is formed separately from the cylinder body 15 and is formed separately from the cylinder body 1.
5 is hermetically screwed and mounted on a screw portion 15a formed on the inner peripheral surface of the upper part. The cylinder forming member 16 has a cylinder forming member main body 23 in which a cylinder hole 16a is formed, and an annular lid which is internally fitted and fixed to an upper end of the cylinder forming member main body 23 and is screwed to the screw portion 15a of the cylinder main body 15. And a part 24.

At the inner peripheral portion of the lid portion 24, a step portion for locking the piston member 3 at the stroke end in the advance direction of the piston member 3 is formed. An annular oil storage portion 17 is formed inside the upper end of the cylinder forming member 16, and the oil storage portion 17 stores lubricating oil. An annular oil passage 19 communicating from the bottom of the annular oil storage portion 17 to the peripheral surface of the cylinder hole is formed, and lubricating oil 18 is provided between the bottom of the oil storage portion 17 and the annular oil passage 19.
Is attached, and the lubricating oil 18 is supplied from the porous fibrous body 21 to the annular oil passage 19.
And gradually supplied to the peripheral surface of the cylinder hole.

The oil storage portion 17 is formed between the cylinder forming member main body 23 and the lid portion 24 and has an annular oil passage 19.
Is also formed between the cylinder forming member main body 23 and the lid 24. Two oil supply portions 22 are provided above the oil storage portion 17 of the lid portion 24. When oil is supplied to the oil storage portion 17, the plug 20 screwed to the oil supply portion 22 is connected to the oil supply portion 22. The oil is removed from one oil replenishing portion 22 while the air is released from one oil replenishing portion 22, and after filling, the plug 20 is screwed again. When oil is not supplied, the oil supply unit 22 is always closed by the plug 20. Other configurations are the same as those of the above embodiment. The porous fibrous body 21 may be accommodated in the whole of the oil accommodating portion 17 and the annular oil passage 19, and the oil impregnated in the porous fibrous body may be supplied. Note that, instead of the porous fibrous body 21, various impregnated bodies that can be impregnated with oil can be applied.

According to the gas spring 1B, the lubricating oil 18 is uniformly and uniformly supplied to the peripheral surface of the cylinder hole from the oil storage portion 17 through the annular oil passage 19, so that the piston member 3 and the cylinder body The sliding portion 15 can be reliably lubricated without oil film breakage in the sliding portion.
Therefore, wear of the sliding portions and the seal members 12, 13, and 14 can be suppressed, and the gas sealing performance can be improved. The oil replenishing part 22 is provided separately from the cylinder body 15 and the cylinder forming member
6, the assembly and repair of the oil supply unit 22 is simplified, and the supply of the lubricating oil 18 can be easily and reliably performed from above the cylinder body 15. Other operations and effects similar to those of the above embodiment can be obtained.

Next, a modified example will be described. 1) Instead of fixing the cylinder forming member 6 to the cylinder main body 2 with the retaining ring 5, a screw may be formed on the outer peripheral portion of the upper end portion of the cylinder forming member 6 and fixed by screwing. 2) The gas springs 1 and 1B can be applied to various uses other than the press device, and can be implemented in a mode in which various changes are added to the gas spring of the above embodiment without departing from the gist of the present invention. Of course, it is.

[0031]

According to the first aspect of the present invention, the cylinder body has a cylinder forming member, and the cylinder forming member forms a cylinder hole, and is formed inside the cylinder body and outside the cylinder forming member. Since the first gas working chamber extension is formed and the second gas working chamber extension is formed inside the piston member, the volume of the gas working chamber is increased to provide a sufficient capacity for the compressed gas. So you can
The gas pressure drop due to the compressed gas leak is suppressed, and the operability of the gas spring can be favorably maintained. In addition, since the overall height of the gas spring can be kept low while expanding the capacity of the gas working chamber, the size of the gas spring can be reduced. High gas spring can be realized.

According to the second aspect of the present invention, the resistance of the gas flow between the first gas working chamber expansion portion and the gas working chamber portion in the cylinder hole can be reduced. The other effects are the same as those of the first aspect. According to the invention of claim 3, when the piston member is at the stroke end in the retreating direction, the inner end portion of the piston member abuts or approaches the bottom surface of the cylinder hole. It can be kept low. Therefore, the overall height of the gas spring can be kept low and downsizing can be achieved. Other effects are the same as those of the second aspect.

According to the fourth aspect of the present invention, the check valve for gas filling is located in the second gas working chamber expansion portion of the piston member when the piston member is at the stroke end in the retreating direction. If the inner end of the piston member abuts or approaches the bottom surface of the cylinder hole at the time of the stroke end in the retreating direction, the check valve for gas filling does not interfere with the piston member. Therefore, the height of the cylinder main body can be kept low, and the overall height of the gas spring can be kept low, and the size can be reduced. The other effects are the same as those of the third aspect.

According to the fifth aspect of the present invention, since the lubricating oil can be uniformly and stably supplied from the oil storage portion to the peripheral surface of the cylinder hole, the sliding portion between the piston member and the cylinder body is reliably lubricated. Therefore, wear of the sliding portion and the seal member can be suppressed, and the gas sealing performance can be improved. In addition, the same effect as any one of the second to fourth aspects can be obtained. According to the invention of claim 6, since the oil supply portion is formed in the cylinder forming member, the structure of the oil supply portion is simplified, the assembly and repair of the oil supply portion are simplified, and the supply of lubricating oil is also performed. It can be easily and reliably performed from above the cylinder body. The other effects are the same as those of the fifth aspect.

[0035]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a gas spring according to an embodiment of the present invention.

FIG. 2 is a plan view of the gas spring.

FIG. 3 is a longitudinal sectional view of a gas spring according to a modified embodiment.

FIG. 4 is an enlarged view of a main part of the gas spring of FIG. 3;

FIG. 5 is a longitudinal sectional view of a gas spring according to the related art.

FIG. 6 is a longitudinal sectional view of a lower casing of the gas spring of FIG. 5;

FIG. 7 is a longitudinal sectional view of another gas spring according to the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas spring 2 Cylinder main body 3 Piston member 4 Gas working chamber 6 Cylinder forming member 6a Cylinder hole 7 First gas working chamber expansion part 8 Second gas working chamber expansion part 9 Communication hole 10 Gas working chamber part in cylinder hole 11 Gas filling Check valve G Compressed gas 1B Gas spring 15 Cylinder body 16 Cylinder forming member 17 Oil storage unit 18 Lubricating oil 22 Oil supply unit

Claims (6)

[Claims] A cylinder body, a piston member movably mounted in a cylinder hole of the cylinder body, a gas working chamber defined by the piston member and the cylinder body,
A gas spring having a compressed gas filled in the gas working chamber and biasing the piston member toward the advancing side, wherein the cylinder body is a cylinder forming member forming the cylinder hole, and is formed separately. An annular first gas working chamber extension forming a part of a gas working chamber inside the cylinder body and outside the cylinder forming member, the piston member being fixedly mounted; A gas spring, wherein a second gas working chamber extension part forming a part of the gas working chamber is formed inside the gas spring. 2. The gas working chamber portion in a cylinder hole, wherein the first gas working chamber extension portion communicates with a gas working chamber portion in a cylinder hole through an annular communication hole communicating with a lower end portion of the cylinder hole. The described gas spring. 3. The gas spring according to claim 2, wherein the inner end of the piston member contacts or approaches the bottom surface of the cylinder hole when the piston member is at the stroke end in the retreating direction. . 4. A gas filling check valve for filling a gas working chamber with a compressed gas is provided on a bottom wall portion of the cylinder main body facing the piston member, the piston member being closer to the piston member than the bottom surface of the cylinder hole. The gas spring according to claim 3, wherein the gas spring is mounted so as to protrude. 5. An annular oil storage portion is formed inside the piston member advance side end of the cylinder forming member,
The gas according to any one of claims 2 to 4, wherein the oil storage portion is filled with lubricating oil, and the lubricating oil in the oil storage portion is configured to be supplied to a peripheral surface of the cylinder hole. spring. 6. The gas spring according to claim 5, wherein the cylinder forming member is provided with an oil supply section for supplying lubricating oil to the oil storage section.