JP3472557B2 - Air cylinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder in which a piston slidably incorporated in a cylinder tube is reciprocated by supplying air to a piston front chamber and a piston rear chamber.

[0002]

2. Description of the Related Art In this type of conventional air cylinder, as shown in FIG. 6, both ends of a cylinder tube 30 are closed by a head cover 31 and a rod cover 32, and a piston 33 is slidable in the cylinder tube 30. Incorporate,
A piston front chamber 34 and a piston rear chamber 35 are provided in the cylinder tube 30, and a piston rod 36 provided in the piston 33 is slidably inserted into a rod insertion hole 37 formed in the rod cover 32, and the head cover is provided. A port 38 communicating with the piston rear chamber 35 is provided in 31, while a port 39 communicating with the piston front chamber 34 is formed in the rod cover 32, and compressed air is alternately supplied to the ports 38, 39. The piston 33 is reciprocated.

In the air cylinder as described above, when the piston fitting clearance 40 formed between the inner peripheral surface of the cylinder tube 30 and the outer peripheral surface of the piston 33 is small, a sliding portion between the cylinder tube 30 and the piston 33 is provided. Image sticking occurs. In order to prevent the seizure, the clearance amount δ ₁₁ of the piston fitting clearance 40 is set to 0.1 mm to 0.7 mm.
It is managed to about mm. In order to prevent air from leaking from the piston fitting clearance 40, a packing groove 41 is formed on the outer peripheral surface of the piston 33, and the outer peripheral portion of the packing 42 attached to the packing groove 41 is connected to the inner peripheral surface of the cylinder tube 30. I try to press it against the surface.

The crushing margin of the packing 42 is about 30% of the outer diameter of the packing 42.

Further, in order to prevent air from leaking between the sliding surfaces of the piston rod 36 and the rod insertion hole 37 formed in the rod cover 32, a gland packing 43 is fitted in the rod insertion hole 37, The inner peripheral surface of the gland packing 43 is pressed against the outer peripheral surface of the piston rod 36.
The gland retainer ring 44 prevents it from coming off.

[0006]

In the conventional air cylinder described above, when the piston 33 reciprocates, the packing 42 moves by rubbing the inner peripheral surface of the cylinder tube 30, so that the packing 42 is worn. Easy to do.
Particularly, when the air cylinder is used in a horizontal position in which the piston rod 36 is moved substantially horizontally, the load of the piston 33 and the piston rod 36 is added to the contact portion between the packing 42 and the cylinder tube 30, and thus the packing 42.
Is likely to be unevenly worn, and the life of the packing 42 is short.

The gland packing 43 for sealing the space between the piston rod 36 and the rod insertion hole 37 has a structure in which the inner circumference of the gland packing 43 is in close contact with the outer circumferential surface of the piston rod 36. Also has the disadvantage of being easily worn.

Further, when the piston 33 and the piston rod 36 reciprocate, the packing 42 holds the cylinder tube 3
Since the piston rod 36 slides in close contact with the inner periphery of 0 and the piston rod 36 slides in close contact with the inner peripheral surface of the gland packing 43, the friction resistance during movement of the piston 33 and the piston rod 36 is large. For this reason, there are disadvantages that the minimum working pressure when the piston 33 is reciprocated is high and the output efficiency of the cylinder is low.

An object of the present invention is to provide an air cylinder having an extremely long life and high output efficiency.

[0010]

In order to solve the above problems, in the present invention, a piston is slidably incorporated in a cylinder tube whose both ends are closed by a head cover and a rod cover, and the rod cover is attached to the piston. In an air cylinder provided with a piston rod that slidably penetrates through the piston, a packing accommodating recess is formed in the piston, and is fitted in the packing accommodating recess with a minute fitting clearance between the inner peripheral surface of the cylinder tube. An annular float packing is installed, and the inner side of the float packing has an inner fitting clearance that forms a positive clearance when the piston is in contact with a part of the inner surface of the cylinder tube. Of.

With the above construction, it is possible to prevent the weight of the piston and the piston rod from being added to the contact portion between the float packing and the cylinder tube in a use state in which the air cylinder is placed horizontally. Therefore, the wear of the float packing during the reciprocating movement of the piston can be suppressed, and an air cylinder having an extremely long life can be obtained.

Further, when the piston reciprocates, the float packing closely adheres to the side surface of the packing accommodating recess, so that air leakage between the front chamber of the piston and the rear chamber of the piston can be prevented satisfactorily, and the float packing is used in the cylinder tube. Since it moves with almost no contact with the inner peripheral surface of
The frictional resistance when the piston reciprocates is extremely small, at the same time, there is almost no wear on the packing, and the cylinder life can be used semipermanently, and the minimum working pressure when reciprocating the piston is reduced, and output efficiency is improved. An extremely high air cylinder can be obtained.

Here, in the rod insertion hole formed in the rod cover, the outer peripheral surface is in close contact with the inner peripheral surface of the rod insertion hole, and a gland bush for forming a bush fitting clearance with the piston rod is provided. , An annular gland float packing that fits a gland pressing ring that prevents the gland bush from coming off and forms a minute mating clearance between the gland bush and the gland pressing ring and the outer peripheral surface of the piston rod. An outer fitting clearance is formed between the outer peripheral surface of the float packing and the inner peripheral surface of the rod insertion hole to form a positive clearance when the piston rod contacts a part of the inner peripheral surface of the gland bush. This prevents the weight of the piston rod from being added to the contact area between the gland float packing and the rod insertion hole. It can be moved in a substantially non-contact state of the piston rod with respect to the ground float packing. Therefore, the frictional resistance during movement of the piston rod is extremely small, and at the same time, there is almost no wear on the packing, and the cylinder life can be used semipermanently, further reducing the minimum working pressure when reciprocating the piston. It is possible to further improve the output efficiency.

A metal ring containing a solid lubricant is attached to the outer circumference of the piston, or the piston is made of a metal containing copper-tin alloy as a main component and containing the solid lubricant, for example. Since the sliding portion of the piston can be lubricated by the solid lubricant, the frictional resistance when the piston moves can be further reduced, and the piston can smoothly reciprocate.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. As shown in FIG. 1, the cylinder tube 1 is made of an aluminum pipe, and the inner peripheral surface thereof is anodized. Both ends of the cylinder tube 1 are closed by a head cover 2 and a rod cover 3, and a piston 4 is slidably incorporated therein. The piston 4 has a piston rod 5,
The piston rod 5 is inserted into a rod insertion hole 6 formed in the rod cover 3 so that its tip end faces the outside.

Inside the cylinder tube 1, a piston front chamber 7a and a piston rear chamber 7b are provided by incorporating the piston 4 therein. A port 8 communicating with the piston rear chamber 7b is formed in the head cover 2, while
The rod cover 3 is provided with a port 9 communicating with the piston front chamber 7a, and the compressed air is alternately supplied to these ports 8 and 9 so that the piston 4 reciprocates.

As shown in FIGS. 1 and 2, the piston 4
Is divided into a front piston 4a and a rear piston 4b,
The front piston 4a is fitted on a small-diameter piston support shaft 5a formed on the piston rod 5, and the knock pin 1
It is fixed to the piston support shaft 5a through 0.

On the other hand, the rear piston 4b is fitted to a small-diameter screw shaft 5b provided at the rear end of the piston support shaft 5a,
It is fixed to the screw shaft 5b by tightening the nut 11 that is screw-engaged with the screw shaft 5b.

A packing accommodating recess 12 is provided between the facing portions of the front piston 4a and the rear piston 4b, and an annular float packing 13 is incorporated in the packing accommodating recess 12.

The piston 4 and the float packing 13 are made of metal such as bearing steel.

The width dimension of the float packing 13 is slightly smaller than the width dimension of the packing accommodating recess 12 so that the float packing 13 can be slightly moved in the axial direction in the packing accommodating recess 12.

The outer surface of the float packing 13 and the seal
Inner peripheral surface of the Linda tube 1 and float packing 13
Between the inner peripheral surface of and the outer peripheral surface of the piston support shaft 5a.
Float packing 1 with mating clearances 14 and 15 formed
Clearance amount δ of the outer fitting clearance 14 on the outer diameter side of 3₁Is the inner diameter
Clearance of inner side fitting clearance 15₂Getting smaller
ing. Also, the clearance amount δ of the inner fitting clearance 15₂Is
Formed on the outer peripheral surface of the piston 4 and the inner peripheral surface of the cylinder tube 1.
Clearance amount of piston fitting clearance 16 ₃Greater than
I'm getting better.

If the outer fitting clearance 14 on the outer diameter side of the float packing 13 is larger than necessary, air leakage will occur between the piston front chamber 7a and the piston rear chamber 7b, and the float packing 13 will serve as a seal. Lost the function of
Further, if it becomes too small, the resistance when the piston 4 moves increases, so the clearance amount δ ₁ of the outer fitting clearance 14 is 0.1 mm or less, preferably 0.01 to
0.05 mm is good.

On the other hand, the clearance amount δ ₂ of the inner fitting clearance 15
Is the piston 4 when the air cylinder is used horizontally.
In order to prevent the load of ( ₃₎ from being added to the float packing 13, it is set larger than the clearance amount δ ₃ of the piston fitting clearance 16. Here, the clearance amount δ ₃ of the piston fitting clearance 16 is preferably about 0.01 to 0.7 mm. Therefore, the inner fitting clearance δ ₂ is 0.8 mm or more, preferably about 0.8 to 5 mm.

These fitting clearances δ ₁ , δ ₂ , δ ₃
Varies depending on the diameter of the cylinder tube 1, the material of the piston 4 and the float packing 13, and the like. Generally, the larger the cylinder tube diameter, the larger the numerical values, and the metal containing the solid lubricant has the smaller numerical values.

As shown in FIGS. 1 and 3, the rod insertion hole 6 formed in the rod cover 3 is a stepped hole, and the large diameter hole portion 6a has a gland bush 17, a gland float packing 18, and a gland. The presser ring 19 is incorporated.

The gland bush 17 is press-fitted into the large-diameter hole portion 6a so that the outer peripheral surface is in close contact with the inner peripheral surface of the large-diameter hole portion 6a. A clearance amount δ ₄ between the inner peripheral surface of the gland bush 17 and the outer peripheral surface of the piston rod 5 is 0.01 to 0.5 m.
A fitting clearance 21 of about m is provided.

The ground float packing 18 is made of metal like the float packing 13 mounted on the piston 4. The gland float packing 18 can be finely moved in the axial direction between the gland bush 17 and the gland pressing ring 19, and between the inner peripheral surface and the outer peripheral surface of the piston rod 5 and between the outer peripheral surface and the inner peripheral surface of the large diameter hole portion 6a. The fitting clearances 22 and 23 are provided in the. The clearance amount δ ₅ of the fitting clearance 22 on the inner diameter side is 0.01 to 0.07 m
On the other hand, the clearance amount δ ₆ of the fitting clearance 23 on the outer diameter side is about 0.6 to 4 mm.

Mating clearances δ ₄ , δ in the gland
₅ and δ ₆ vary depending on the size of the piston rod diameter and the material of the gland bush and gland float packing. In general, the larger the piston rod diameter, the larger the numerical values, and the metal containing the solid lubricant has the smaller numerical values.

Now, in the state shown in FIG. 1, when compressed air is supplied to the port 8 provided in the head cover 2,
The piston 4 moves toward the rod cover 3 and
When compressed air is supplied to the port 9 formed in the rod cover 3, the piston 4 moves toward the head cover 2.

In the cylinder tube 1, the piston 4
When moving, the outer fitting clearance 14 of the float packing 13 mounted on the piston 4 is extremely small, so that air hardly leaks from the outer fitting clearance 14. When the piston 4 moves, the side surface of the float packing 13 on the front side in the moving direction is in close contact with the side surface of the front piston 4a or the side surface of the rear piston 4b, which prevents air leakage.

On the other hand, when the compressed air is supplied from the port 9 of the rod cover 3 to the piston front chamber 7a, the gland float packing 18 comes into close contact with the side surface of the gland bush 17. In addition, since the clearance amount δ ₅ of the fitting clearance 22 provided on the inner diameter side is as small as about 0.01 to 0.07 mm, the compressed air in the piston front chamber 7a is transferred from the rod insertion hole 6 to the outside. It is prevented from leaking.

Since the outer fitting clearance 14 of the float packing 13 mounted on the piston 4 is smaller than the inner fitting clearance 15, and the inner fitting clearance 15 is larger than the piston fitting clearance 16, the air cylinder is placed horizontally. The load of the piston 4 is not applied to the float packing 13 in the used state.

Since the fitting clearance 23 on the outer diameter side of the gland float packing 18 is larger than the fitting clearance 21 formed between the gland bush 17 and the piston rod 5, the load of the piston rod 5 causes the gland float packing 18 to move. It is not crushed in the radial direction.

Therefore, the frictional resistance during movement of the piston 4 is extremely small, and since the frictional resistance is small, the piston 4 can be smoothly reciprocated even with an extremely small operating pressure, and the air cylinder having high output efficiency. Can be obtained.

In the embodiment, the outer fitting clearance 1
4, inner fitting clearance 15 and piston fitting clearance 16
The relationship between clearances δ ₁ , δ ₂ , and δ ₃ is δ ₁ <δ ₃ <δ ₂
However, the present invention is not limited to this. The point is that a positive clearance may be formed in the inner fitting clearance δ ₂ when the piston 4 contacts a part of the inner peripheral surface of the cylinder tube 1.

Further, the fitting clearance 21 formed on the inner diameter side of the gland bush 17, the gland float packing 1
The relationship between the clearance amounts δ ₄ , δ ₅ , and δ ₆ of the fitting clearance 22 on the inner diameter side and the fitting clearance 23 on the outer diameter side of 8 is δ ₆ > δ ₄
Although> δ ₅ , it is not limited to this. In short, it is sufficient that a positive clearance is formed in the fitting clearance 23 on the outer diameter side of the gland float packing 18 when the piston rod 5 is in an eccentric state in which it contacts a part of the inner circumference of the gland bush 17.

As shown in FIG. 4, the float packing 13
By forming the ring groove 24 on both side surfaces of the, and attaching a sealing material 25 such as an O ring to the ring groove 24,
It is possible to more effectively seal between the opposing surfaces of the float packing 13 and the front piston 4a and the rear piston 4b, and it is possible to more effectively prevent air leakage.

In the example shown in FIGS. 1 and 4, the float packing 13 is fitted to the piston support shaft 5a, but the support of the float packing 13 is not limited to this. For example, as shown in FIG. Alternatively, the protruding shaft portion 26 may be formed on the side surface of the front piston 4a, and the float packing 13 may be fitted to the protruding shaft portion 26. Such a protruding shaft portion 26 may be provided on the side surface of the rear piston 4b instead of the front piston 4a. [Experimental Example 1] Now, an air cylinder having dimensions shown in Table 1 is formed in each part of the air cylinder shown in FIGS. 1 to 3, and ports formed in the head cover 2 and the rod cover 3 of the air cylinder. When compressed air was alternately supplied to 8 and 9 and the life of the float packing 13 was measured, the air cylinder operated smoothly even though the movement amount of the piston 4 exceeded 50,000 km.

As a comparison, when the life of the packing 42 of the conventional air cylinder shown in FIG. 6 was measured, when the moving amount of the piston exceeded 1,000 km, air leakage occurred and it became inoperable. Table 2 shows the dimensions of each part of the conventional air cylinder.

In the test, both the invention product and the comparative product were subjected to compressed air supply pressure = 4 kg / cm ² , oil-free, frequency = 1 reciprocation / sec, and piston speed = 1500 mm / sec.

As is apparent from the experiment, it can be understood that the product of the present invention has a life longer than that of the comparative product by 50 times or more.

[0043]

[Table 1]

[0044]

[Table 2]

[Experimental Example 2] When the output efficiencies of the air cylinder of the present invention shown in Table 1 and the air cylinder of the comparative article shown in Table 2 were measured, the results shown in Tables 3 and 4 were obtained.

At the time of measuring the output, an air cylinder was arranged on the platform scale, the air cylinder was fixed, and compressed air was supplied from the port so that the deflection of the pointer of the platform scale was read.

The theoretical output shown in Tables 3 and 4 is a value represented by the product of the pressure receiving area of the piston and the pressure of the compressed air.

[0048]

[Table 3]

[0049]

[Table 4]

As is apparent from Tables 3 and 4, it can be understood that the output efficiency of the air cylinder of the present invention is extremely high. [Experimental Example 3] The air cylinder of the present invention shown in Table 1 and Table 2
When the response (favorability) in the air cylinder of the comparative product shown in (4) was measured, the results shown in Table 5 and Table 6 were obtained.

[0051]

[Table 5]

[0052]

[Table 6]

From the measurement results shown in Tables 5 and 6, it is understood that the sensitivity of the product of the present invention is superior to that of the comparative product.
From the measurement results, it can be understood that the friction resistance of the air cylinder of the present invention is smaller than that of the air cylinder of the comparative product. [Experimental Example 4] The air leakage at the piston sliding portion and the piston rod sliding portion of the air cylinder of the present invention shown in Table 1 was measured.

When measuring the air leakage of the sliding portion of the piston,
A pressure tank having a capacity of 2 liters and a tank internal pressure of 2 kg / cm ² was connected to the port 8 of the head cover 2. The time required for the pressure in the pressure tank to change from 2 kg / cm ² to 1 kg / cm ² was measured, and it took 1 minute 32 seconds.

When measuring the air leakage at the sliding portion of the piston rod, the port 8 of the head cover 2 was closed and the port 9 of the rod cover 3 was connected to the same pressure tank as above. The pressure of the pressure tank is 2kg / cm ² to 1k
When the time required to reach g / cm ² was measured, it was 2 minutes 3
It took 6 seconds.

Any air leakage is so small that it can be ignored, and considering the good output efficiency, the energy efficiency is extremely good. [Experimental Example 5] A test was conducted on the adhesion of the air cylinder of the product of the present invention shown in Table 1. During the test, rod cover 3
The port 9 of the head cover 2 is set to atmospheric pressure, the pressure of 4 kg / cm ² is applied to the port 8 of the head cover 2, and the port 8 of the head cover 2 is set to atmospheric pressure after 1 hour, 24 hours, and 48 hours. A minimum operating pressure (0.01 kg / cm ² ) was applied to the port 9 of the cover 3 to confirm whether or not the piston 4 moved.

After any of the above times, the piston 4 moved and there was no sticking. As described above, since the air cylinder of the present invention has no sticking at all, it is extremely suitable for use as a disaster prevention cylinder for closing the fire door in an emergency. [Experimental Example 6] The air cylinders of the present invention shown in Table 1 were tested for the presence of stick-slip phenomenon. During the test, compressed air was supplied to the port 8 of the head cover 2, and the supply pressure was 0.5 kg / cm ² , 1 kg / c.
m ² , 2 kg / cm ² , 3 kg / cm ² and 4 kg /
The pressure is changed to cm ² , and the variable throttle connected to the port 9 of the rod cover 3 is adjusted for each pressure change so that the moving speed of the piston 4 is 5 mm / sec regardless of the air supply pressure. The presence or absence of the slip phenomenon was investigated.

As a result, even if the air supply pressure changes, the stick-slip phenomenon does not occur, and it can be understood that the air cylinder of the present invention is suitable for use as a low speed cylinder.

[0059]

As described above, in the present invention, the annular float packing is incorporated in the packing accommodating recess formed in the piston, and the piston is fitted with the outer fitting clearance formed on the outer diameter side of the float packing. Since the positive clearance is formed in contact with the inner peripheral surface of the cylinder tube, it is possible to obtain an air cylinder having a very long life with little wear of the float packing and a very low movement resistance and a high output efficiency.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of an air cylinder according to the present invention.

2 is an enlarged cross-sectional view of the piston sliding portion of FIG.

3 is an enlarged cross-sectional view of the piston rod sliding portion of FIG.

4 is a sectional view showing another example of the float packing of the air cylinder shown in FIG.

5 is a cross-sectional view showing another example of supporting the float packing of the air cylinder shown in FIG.

FIG. 6 is a vertical sectional front view showing a conventional air cylinder.

[Explanation of symbols]

1 cylinder tube 2 head cover 3 rod cover 4 pistons 5 piston rod 6 Rod insertion hole 12 Packing receiving recess 13 float packing 14 Outer mating clearance 15 Internal fitting clearance 17 Grand Bush 18 Grand Float Packing 19 Grand presser ring 21, 22, 23 Mating clearance

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 2001-227509 (JP, A) JP 11-154692 (JP, A) JP 11-117912 (JP, A) JP 11-13885 (JP, A) JP-A-11-2210 (JP, A) JP-A-10-340931 (JP, A) JP-A-10-9318 (JP, A) JP-A-9-287668 (JP, A) Kaihei 8-200314 (JP, A) JP 8-4710 (JP, A) JP 7-224807 (JP, A) Actual flat 3-57502 (JP, U) Actual flat 1-166860 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) F15B 15/14 345 F15B 15/14 355 F16J 1/08 F16J 9/00

Claims (2)

(57) [Claims] 1. An air cylinder in which a piston is slidably incorporated in a cylinder tube whose both ends are closed by a head cover and a rod cover, and the piston is provided with a piston rod that slidably penetrates the rod cover. A packing accommodating recess is formed in the ring accommodating recess, and an annular float packing fitted with a minute fitting clearance between the inner peripheral surface of the cylinder tube and the packing accommodating recess is incorporated into the packing accommodating recess. An air cylinder having an inner fitting clearance for forming a positive clearance when the piston comes into contact with a part of the inner peripheral surface of the cylinder tube. 2. A gland bush having an outer peripheral surface in close contact with an inner peripheral surface of the rod insertion hole and forming a bush fitting clearance with the piston rod in a rod insertion hole formed in the rod cover. The gland bush is fitted with a gland retainer ring that prevents the gland bush from slipping out, and a minute fit clearance is formed between the gland bush and the gland retainer ring with the outer peripheral surface of the piston rod. An annular gland float packing is incorporated, and an outer side that forms a positive clearance between the outer peripheral surface of the float packing and the inner peripheral surface of the rod insertion hole in the offset state where the piston rod contacts a part of the inner peripheral surface of the gland bush 2. A fitting clearance is provided, which is characterized in that
Air cylinder described in.