JP2002227807A - Air cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air cylinder with a long service life and a high output efficiency. SOLUTION: A packing storage recessed part 12 is formed in a slidable packing 4 incorporated in a cylinder tube 1, and an annular float packing 13 is incorporated in the packing storage recessed part 12. An external fitting clearance 14 formed between the outer peripheral surface of the float packing 13 and the inner peripheral surface of the cylinder tube 1 is made smaller than an internal fitting clearance 15 formed on the inner diameter side of the float packing 13, and the internal fitting clearance 15 is made larger than a piston fitting clearance 16 formed between the outer peripheral surface of the piston 4 and the inner peripheral surface of the cylinder tube 1 to prevent the load of the piston 4 from being applied to the float packing 13. Thus, the service life of the air cylinder can be extended, and a frictional resistance caused when the piston is moved can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder which reciprocates a piston slidably incorporated in a cylinder tube 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 slidably inserted into 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. The port 31 is provided with a port 38 communicating with the piston rear chamber 35, while the rod cover 32 is formed with a port 39 communicating with the piston front chamber 34, and compressed air is alternately supplied to each of the ports 38 and 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, the sliding portion between the cylinder tube 30 and the piston 33 is Seizure occurs. To prevent with its burn, the gap amount [delta] ₁₁ of the piston fitting clearance 40 0.1Mm～0.7
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 attached to the inner peripheral surface of the cylinder tube 30. They are pressed against the surface.

Here, the crushing allowance of the packing 42 is about 30% of the outer diameter of the packing 42.

In order to prevent air from leaking from 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 into the rod insertion hole 37, The inner peripheral surface is pressed against the outer peripheral surface of the piston rod 36 and the gland packing 43 is pressed.
Are prevented from coming off by a gland holding ring 44.

[0006]

In the above-mentioned conventional air cylinder, when the piston 33 reciprocates, the packing 42 moves while rubbing the inner peripheral surface of the cylinder tube 30. Easy to do.
In particular, 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 applied to the contact portion between the packing 42 and the cylinder tube 30.
However, there is an inconvenience that uneven wear easily occurs and the life of the packing 42 is short.

The gland packing 43 for sealing between the piston rod 36 and the rod insertion hole 37 has a structure in which the inner periphery thereof is in close contact with the outer peripheral surface of the piston rod 36, so that the gland packing 43 is brought into contact with the piston rod 36. However, there is a disadvantage that it is also easily worn.

Further, when the piston 33 and the piston rod 36 reciprocate, the packing 42 is attached to the cylinder tube 3.
Since the piston rod 36 slides in a state in which the piston 33 closely contacts the inner peripheral surface of the gland packing 43, the frictional resistance when the piston 33 and the piston rod 36 move is large. For this reason, there is a disadvantage that the minimum operating pressure when the piston 33 reciprocates is high, and the output efficiency of the cylinder is low.

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

[0010]

According to 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 the air cylinder provided with a piston rod that slidably penetrates, a packing receiving recess is formed in the piston, and a small fitting clearance is fitted between the packing receiving recess and the inner peripheral surface of the cylinder tube. An annular float packing is incorporated, and the inner side of the float packing is provided with an inner fitting clearance that forms a plus clearance in a deflected state where the piston contacts a part of the inner peripheral surface of the cylinder tube. It is.

[0011] According to the above configuration, 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 the use state in which the air cylinder is placed horizontally. Therefore, wear of the float packing during reciprocation of the piston can be suppressed, and an air cylinder having an extremely long life can be obtained.

Also, when the piston reciprocates, the float packing comes into close contact with the side surface of the packing housing recess, so that air leakage between the piston front chamber and the piston rear chamber can be effectively prevented. To move almost in non-contact with the inner peripheral surface of the
The frictional resistance during the reciprocating movement of the piston is extremely small, and at the same time, there is almost no wear on the packing.The cylinder life can be used semi-permanently. Of the air cylinder can be obtained.

A ground bush whose outer peripheral surface is in close contact with the inner peripheral surface of the rod insertion hole and forms a bush fitting clearance with the piston rod in a rod insertion hole formed in the rod cover. An annular gland float packing in which a gland holding ring for retaining the gland bush is fitted, and a small fitting clearance is formed between the gland bush and the gland holding ring with the outer peripheral surface of the piston rod. And 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 in a deflected state in which 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 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 the movement of the piston rod is extremely small, and at the same time, there is almost no wear of the packing, the cylinder life can be used semi-permanently, and the minimum operating pressure when reciprocating the piston is further reduced. And the output efficiency can be further increased.

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

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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 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 and has a distal end facing 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. The head cover 2 is formed with a port 8 communicating with the piston rear chamber 7b.
The rod cover 3 is provided with a port 9 communicating with the piston front chamber 7a, and the piston 4 reciprocates by alternately supplying compressed air to each of the ports 8, 9.

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 to a small-diameter piston support shaft 5a formed on the piston rod 5, and the knock pin 1
0 to the piston support shaft 5a.

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 screwed to the screw shaft 5b.

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

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

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

The outer peripheral surface of the float packing 13 is
Inner Peripheral Surface of Linda Tube 1 and Float Packing 13
Between the inner peripheral surface of the shaft and the outer peripheral surface of the piston support shaft 5a.
The fitting gaps 14 and 15 are formed, and the float packing 1 is formed.
3, the clearance amount δ of the outer fitting clearance 14 on the outer diameter side₁Is the inside diameter
Clearance δ of the inner mating clearance 15 on the side_TwoSmaller
ing. Also, the clearance amount δ of the inner fitting clearance 15_TwoIs
Formed on the outer peripheral surface of piston 4 and the inner peripheral surface of cylinder tube 1
Clearance δ of piston fitting clearance 16 to be formed _ThreeGreater than
I'm getting smart.

If the outer fitting clearance 14 on the outer diameter side of the float packing 13 is larger than necessary, air leakage occurs between the piston front chamber 7a and the piston rear chamber 7b, and the float packing 13 serves as a seal. Lose the function of
Also, if too small, the resistance at the time of the movement of the piston 4 is increased, the gap amount [delta] ₁ of the outer fitting gap 14, 0.1 mm or less, preferably, 0.01
0.05 mm is preferred.

On the other hand, the clearance amount δ ₂ of the inner fitting clearance 15
Is the piston 4 when the air cylinder is placed horizontally.
In order to prevent this load from being applied to the float packing 13, the clearance amount δ ₃ of the piston fitting clearance 16 is set to be larger. Here, the gap amount [delta] ₃ of the piston fitting clearance 16 is about 0.01~0.7mm are preferred. Therefore the inner fitting gap [delta] ₂ is 0.8mm or more, preferably from about 0.8～5Mm.

Each of these fitting clearance amounts 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, each numerical value increases as the cylinder tube diameter increases, and each numerical value decreases as the metal contains a solid lubricant.

As shown in FIGS. 1 and 3, the rod insertion hole 6 formed in the rod cover 3 is a stepped hole, and a gland bush 17, a gland float packing 18 and a gland are provided in the large diameter hole 6a. A holding ring 19 is incorporated.

The ground bush 17 is press-fitted into the large-diameter hole 6a so that the outer peripheral surface is in close contact with the inner peripheral surface of the large-diameter hole 6a. The clearance δ ₄ between the inner peripheral surface of the ground bush 17 and the outer peripheral surface of the piston rod 5 is 0.01 to 0.5 m.
A fitting gap 21 having a length 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 is finely movable in the axial direction between the gland bush 17 and the gland holding 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 6a. Are provided with fitting gaps 22 and 23. Gap amount [delta] ₅ of the fitting gap 22 of the inner diameter side 0.01~0.07m
m, while the clearance amount δ ₆ of the fitting clearance 23 on the outer diameter side is about 0.6 to 4 mm.

The fitting clearance amounts δ ₄ and δ in the ground portion
_5, [delta] ₆ the size of the piston rod diameter, varies depending on the material of gland bush or ground float packing. Generally, the larger the piston rod diameter, the larger the numerical value, and the smaller the value of the metal containing the solid lubricant, the smaller the numerical value.

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.

The piston 4 in the cylinder tube 1
Is moved, the outside fitting clearance 14 of the float packing 13 mounted on the piston 4 is extremely small, so that there is almost no air leakage from the outside fitting clearance 14. Further, when the piston 4 moves, the float packing 13 has its side surface on the front side in the moving direction closely contacting the side surface of the front piston 4a or the side surface of the rear piston 4b, and the close contact prevents air leakage.

On the other hand, the gland float packing 18 comes into close contact with the side surface of the gland bush 17 when compressed air is supplied from the port 9 of the rod cover 3 to the piston front chamber 7a. Further, the gap amount [delta] ₅ of fitting gap 22 formed in the inner diameter side, since they are very small in order 0.01～0.07Mm, outside compressed air piston front chamber 7a from the rod insertion hole 6 Leakage is prevented.

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. In use, the load of the piston 4 is not applied to the float packing 13.

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 gland float packing 18 is moved by the load of the piston rod 5. It is not crushed in the radial direction.

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

In the embodiment, the outer fitting clearance 1
4. Inner fitting clearance 15 and piston fitting clearance 16
The relationship between the clearance amounts δ ₁ , δ ₂ , δ ₃ is expressed as δ ₁ <δ ₃ <δ ₂
However, the present invention is not limited to this. In short, in a state in which the piston 4 is in contact with the portion the inner circumferential surface of the cylinder tube 1, may be in the inner fitting gap [delta] ₂ as the positive gap is formed.

The fitting clearance 21 formed on the inner diameter side of the ground bush 17 and the ground float packing 1
8, 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 is expressed as δ ₆ > δ ₄
> Was [delta] _5, but not limited thereto. 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 in the deflected state where the piston rod 5 contacts a part of the inner periphery of the gland bush 17.

As shown in FIG. 4, the float packing 13
By forming a ring groove 24 on both sides of the seal member 25 and attaching a sealing material 25 such as an O-ring to the ring groove 24,
The seal between the float packing 13 and the opposing surfaces of the front piston 4a and the rear piston 4b can be more effectively sealed, and air leakage can be more effectively prevented.

In the example shown in FIGS. 1 and 4, the float packing 13 is fitted to the piston support shaft 5a. However, the support of the float packing 13 is not limited to this. For example, as shown in FIG. Alternatively, a projecting shaft 26 may be formed on the side surface of the front piston 4a, and the float packing 13 may be fitted to the projecting shaft 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 was formed for each part of the air cylinder shown in FIGS. 1 to 3 and ports formed on the head cover 2 and the rod cover 3 of the air cylinder. When the life of the float packing 13 was measured by alternately supplying the compressed air to the air cylinders 8 and 9, the air cylinder operated smoothly despite the movement amount of the piston 4 exceeding 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 piston moved more than 1,000 km, air leakage occurred and operation became impossible. Table 2 shows the dimensions of each part of the conventional air cylinder.

The test was performed with the compressed air supply pressure = 4 kg / cm ² , no lubrication, frequency = 1 reciprocation / sec, and piston speed = 1500 mm / sec.

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

[0043]

[Table 1]

[0044]

[Table 2]

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

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

Here, 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 clear from Tables 3 and 4, it can be understood that the air cylinder of the present invention has an extremely high output efficiency. [Experimental example 3] The air cylinder of the present invention shown in Table 1 and Table 2
Table 5 and Table 6 were obtained when the response (positive sensitivity) of the comparative product indicated by in the air cylinder was measured.

[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 comparative air cylinder. [Experimental Example 4] The air leakage of 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 piston sliding part,
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. When the time required for the pressure in the pressure tank to change from 2 kg / cm ² to 1 kg / cm ² was measured, it took 1 minute and 32 seconds.

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

Any air leakage is negligibly small, and the energy efficiency is extremely good considering the good output efficiency. [Experimental Example 5] A test was conducted on the fixation of the air cylinder of the present invention shown in Table 1. For the test, rod cover 3
The port 9 of the head cover 2 is set to atmospheric pressure, a pressure of 4 kg / cm ² is applied to the port 8 of the head cover 2, and after 1 hour, 24 hours, and 48 hours, the port 8 of the head cover 2 is set to atmospheric pressure, A minimum operating pressure (0.01 kg / cm ² ) was applied to the port 9 of the cover 3 to check whether the piston 4 moved.

After any of the above-mentioned times, the piston 4 moved, and there was no sticking. As described above, the air cylinder of the present invention has no sticking at all, and thus is extremely suitable for use as a disaster prevention cylinder for closing a fire door in an emergency. [Experimental Example 6] An air cylinder of the present invention shown in Table 1 was tested for the presence or absence of a stick-slip phenomenon. At the time of 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 /
cm ² , the variable throttle connected to the port 9 of the rod cover 3 was adjusted for each change in the pressure, and the moving speed of the piston 4 was 5 mm / sec regardless of the air supply pressure. The presence or absence of a slip phenomenon was examined.

As a result, even if the air supply pressure changed, no stick-slip phenomenon occurred, and it was understood that the air cylinder of the present invention was suitable for use as a low-speed cylinder.

[0059]

As described above, according to the present invention, an annular float packing is incorporated into a packing accommodating recess formed in the piston, and the outer fitting clearance formed on the outer diameter side of the float packing is used by the piston. Since the plus clearance is formed in a state of being 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 moving resistance and high output efficiency.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view of a piston sliding portion of FIG.

FIG. 3 is an enlarged sectional view of a sliding portion of the piston rod of FIG. 1;

FIG. 4 is a sectional view showing another example of the float packing of the air cylinder shown in FIG. 1;

FIG. 5 is a sectional view showing another example of supporting the float packing of the air cylinder shown in FIG. 1;

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder tube 2 Head cover 3 Rod cover 4 Piston 5 Piston rod 6 Rod insertion hole 12 Packing accommodation recess 13 Float packing 14 Outer fitting clearance 15 Inner fitting clearance 17 Ground bush 18 Ground float packing 19 Ground press ring 21, 22, 23 Mating clearance

Claims (2)

[Claims] 1. An air cylinder, wherein 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 slidably penetrating the rod cover. A packing receiving recess is formed in the packing receiving recess, and an annular float packing fitted with a small fitting clearance between the packing receiving recess and the inner peripheral surface of the cylinder tube is incorporated.On the inner diameter side of the float packing, An air cylinder having an inner fitting clearance for forming a positive clearance in a deflected state in which a piston contacts a part of an inner peripheral surface of a cylinder tube. 2. A ground bush whose outer peripheral surface is in close contact with the inner peripheral surface of the rod insertion hole and forms a bush fitting clearance with the piston rod in a rod insertion hole formed in the rod cover. A gland holding ring for preventing the gland bush from falling into the cylinder tube is fitted, and a small fitting clearance is formed between the gland bush and the gland holding ring and the outer peripheral surface of the piston rod. An annular ground float packing is incorporated, and between the outer peripheral surface of the float packing and the inner peripheral surface of the rod insertion hole, an outer side in which the piston rod forms a plus clearance in an offset state in which the piston rod contacts a part of the inner peripheral surface of the gland bush. 2. A fitting clearance is provided.
The air cylinder described in the above.