JPH10141323A - Hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cavitation noise from generating when a first slider and a second slider simultaneously expands or contracts. SOLUTION: A hollowly cylindrical first slider 20 arranged slidable in the axial direction is provided inside a fixed cylinder 10 in a slidable manner in the advancing direction and in retreating direction with respect to the fixed cylinder 10. When pressure oil is supplied to or discharged from inside the fixed cylinder 10, it is designed so that pressure oil filled in the fixed cylinder beforehand is supplied to and discharged from inside the first slider 20 via a pressure oil supply/discharge hole 23 provided on the first slider 20. It is also designed so that pressure oil passing through the pressure oil supply/ discharge hole 23 is squeezed by an orifice composed by a step provided in the interior of the pressure oil supply/discharge hole 23 in an inwardly protruding manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic cylinder, and more particularly, to a hydraulic cylinder suitably used as an elevator drive for a home elevator.

[0002]

2. Description of the Related Art In low-rise houses, middle-rise houses and the like, elevators which are lifted and lowered by hydraulic cylinders are employed, and in particular, single-speed single units as disclosed in Japanese Patent Application Laid-Open No. 5-330762. Dynamic telescopic cylinders are frequently used.

FIG. 4 shows an example of a constant-speed single-acting telescopic cylinder. This telescopic cylinder is a fixed cylinder 5
A first slider 52 having a hollow cylindrical shape is slidably disposed in the first slider 1, and a second slider 53 is slidably disposed in the first slider 52. Further, a third slider 54 is slidably disposed within the second slider 53. The first slider 52 slides in a direction in which the first slider 52 advances from the inside of the fixed cylinder 51 by supplying the pressurized oil into the fixed cylinder 51, and the first slider 52 advances in the inside of the fixed cylinder 51. By sliding in the direction, the pressure oil pre-filled in the fixed cylinder 51 is supplied into the first slider 52 through the pressure oil supply / discharge hole 52 a provided on the peripheral surface of the first slider 52. It has become. When the pressure oil is supplied into the first slider 52 in this manner, the second slider 53 arranged in the first slider 52 slides in the advance direction with respect to the first slider 52. I have.

As described above, at the same time as the first slider 52 in the fixed cylinder 51 extends, the second slider 53 in the first slider 52 extends at a constant speed.
When the third slider 53 extends at a constant speed, the third
The elevator body attached to the tip of the slider 54 rises.

When the second slider 53 slides in the forward direction in the first cylinder 52, the pressure oil previously filled in the first cylinder 52 is supplied to the pressure oil supply provided on the peripheral surface of the second slider 53. The air is supplied into the second slider 53 through the discharge hole 53a. And
When the pressure oil is supplied into the second slider 53 in this manner, the third slider 54 arranged in the second slider 53 slides in the advance direction with respect to the second slider 53.

On the other hand, when the pressure oil in the fixed cylinder 51 is discharged in a state where the first slider 52, the second slider 53, and the third slider 54 are extended, respectively,
As the first slider 52 slides in the retreating direction, the pressure oil in the first slider 52 flows into the fixed cylinder 51 through the pressure oil supply / discharge hole 52a and is discharged. Further, while the second slider 53 slides in the retreating direction, the pressure oil in the second slider 53 is released from the pressure oil supply / discharge hole 53a.
Through the first slider 52 to be discharged.
Thereby, the third slider 54, the second slider 53
And the first slider 52 are simultaneously contracted at a constant speed.

[0007]

The pressure oil supply / discharge holes 52a and 53a provided on the peripheral surfaces of the first slider 52 and the second slider 53, respectively, usually have a constant inner diameter. To this end, each of the pressure oil supply / discharge holes 52a and 5
When the pressure oil passes through 3a, its flow velocity may increase. In particular, when the third slider 54, the second slider 53, and the first slider 52 are each in the contracted state, the weight of the elevator body and the like is added to the first slider 52 and the second slider 53, so that each hydraulic oil is compressed. The flow velocity of the pressure oil passing through the supply / discharge holes 52a and 53a increases, and cavitation is likely to occur.
Cavitation may cause noise.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a hydraulic cylinder capable of preventing generation of noise due to cavitation when the first slider and the second slider expand and contract simultaneously. To provide.

[0009]

SUMMARY OF THE INVENTION A hydraulic cylinder according to the present invention includes a hollow cylindrical first slider disposed in a fixed cylinder so as to be slidable in the axial direction, and an axial center in the first slider. And the second slider is slidably disposed, and when the pressure oil is supplied and discharged into the fixed cylinder, the first slider slides in the forward and backward directions with respect to the fixed cylinder, respectively. And a hydraulic cylinder in which pressure oil previously filled in the fixed cylinder is supplied and discharged into the first slider through a pressure oil supply / discharge hole provided in the first slider, The pressure oil passing through the pressure oil supply / discharge hole is throttled by an orifice.

The orifice is constituted by a step provided so as to protrude inward inside the pressure oil supply / discharge hole.

The orifice is formed by closing a part of one end face opening of the pressure oil supply / discharge hole.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partially cutaway front view showing an example of a hydraulic cylinder according to an embodiment of the present invention. This hydraulic cylinder is, for example, a constant-speed single-acting telescopic cylinder used as a lift drive device for a home elevator, and has a hollow cylindrical fixed cylinder 10 disposed vertically and a coaxial inside the fixed cylinder 10. A hollow cylindrical first slider 20 slidably disposed in a state, a hollow cylindrical second slider 30 slidably disposed in the first slider 20 coaxially, and a coaxial inside the second slider 30 And a cylindrical third slider 40 slidably disposed in a state.

The upper end of the first slider 20 can advance upward from the upper end surface of the fixed cylinder 10. The upper end of the second slider 30 also extends upward from the upper end surface of the first slider 20. It is possible to advance to. The upper end of the third slider 40 disposed inside the second slider 30 can also advance upward from the upper end of the second slider 30.

The fixed cylinder 10 is provided with a fixed tube main body 11 which is disposed vertically with the upper end face open.
A pressure oil port 1 for supplying pressure oil into the fixed tube body 11 and discharging the pressure oil from the fixed tube body 11
3 are provided.

Fixed tube body 11 of fixed cylinder 10
The first slider 20 provided therein has a first tube 21 fitted concentrically with the fixed tube main body 11 of the fixed cylinder 10.
A first piston 22 is attached to a lower end of the first piston 22.
The upper end of the first tube 21 is in a state of protruding above the fixed tube main body 11, and the first piston 22 slides upward in the fixed tube main body 11, so that the first tube 21 is fixed to the fixed tube main body 11. As the first piston 22 slides down inside the fixed tube main body 11 as it advances from the first tube 11, the first tube 21 retreats into the fixed tube main body 11. The portion of the first tube 21 projecting upward from the fixed cylinder 10 is supported in a sealed state on the inner peripheral surface of the open upper end surface of the fixed tube main body 11 of the fixed cylinder 10.

In the fixed tube main body 11, the space above the first piston 22 is filled with pressurized oil and sealed beforehand, with the first piston 22 disposed therein being lowered most. ing.

The first piston 22 is connected to the fixed tube main body 1.
A cylindrical piston body 22a which is slid in pressure contact with the inner peripheral surface of the piston body 1 in a liquid-tight manner;
And a cylindrical portion 22b projecting upward from above. The lower end of the first tube 21 is inserted into the cylindrical portion 22b. In the present embodiment, the lower end surface of the first tube 21 is located slightly above the upper end surface of the piston body 22a.

At the lower end of the cylindrical portion 22b of the first piston 22 located below the first tube 21, the inside and outside of the cylindrical portion 22b below the first tube 21 inserted into the cylindrical portion 22b are connected. The cylindrical portion 22b
Are horizontally provided at appropriate intervals in the circumferential direction.

FIG. 2 is an enlarged sectional view showing the pressure oil supply / discharge hole 23. As shown in FIG. At the center of each pressure oil supply / discharge hole 23 in the axial direction, a step portion 23a projecting inward over the entire circumference
Are provided, and the inside of the step portion 23a is
The orifice 23c is provided. Each orifice 23c
Are provided concentrically with the respective ends of the respective pressure oil supply / discharge holes 23, and the step portion 23a is formed at the end inner peripheral surface of each pressure oil supply / discharge hole 23 except for the step portion 23a, Each end surface is continuous via a tapered surface 23b whose inner diameter gradually increases toward the end face.

As shown in FIG. 1, the piston body 22a
Is provided with a check valve 24 for pressure compensation. The check valve 24 is connected to the piston body 22a.
The valve body 24c is slidable in the up-down direction in a through hole 22c penetrating in the up-down direction through the axis of the valve body 24c. The valve element 24c is urged downward by a compression spring 24e, and the entire valve element 24c is
In this state, the through hole 22c is closed. Then, the valve element 24c is connected to the compression spring 2
When the through hole 22c is slid upward against the urging force of 4e, the through hole 22c communicates between the lower side and the upper side of the piston body 22a.

The second slider 30 provided in the first tube 21 of the first slider 20 is also the first slider 2.
0 and the second tube 3 fitted concentrically with the first tube 21 of the first slider 20.
1 and a second tube 31 provided at the lower end of the second tube 31.
And a piston 32. And the second tube 3
The upper end of the first tube 21 projects upward from the upper end surface of the first tube 21, and the second piston 32 slides upward in the first tube 21, thereby causing the second tube 31 to move upward. And the second piston 32 slides downward in the first tube 21 so that the second tube 32
1 to enter. The portion of the second tube 31 protruding upward from the first tube 21 is supported in a sealed state on the inner peripheral surface of the upper end surface of the first tube 21 in the first slider 20.

In the first tube 21, the space above the second piston 32 is filled with pressurized oil and sealed beforehand, with the second piston 32 disposed therein being lowered most. I have.

The lower end of the cylindrical portion 32b of the second piston 32 penetrates in a horizontal direction so as to communicate the inside and the outside of the cylindrical portion 22b below the second tube 31 inserted into the cylindrical portion 32b. A plurality of pressure oil supply / discharge holes 33 are provided at appropriate intervals in the circumferential direction. Each pressure oil supply and discharge hole 3
3 also have respective pressure oil supply / discharge holes 23 provided in the first piston 22.
As shown in FIG. 2, a stepped portion 33 protruding inward over the entire circumference is provided at a central portion in the axial center direction.
a is provided, and the inside thereof is an orifice 33c.
It has become. Each stepped portion 33a has a tapered surface 3 at each end inner peripheral surface of each pressure oil supply / discharge hole 33 except for the stepped portion 33a.
3b.

A check valve 3 for pressure compensation is provided at the axial center of the piston body 32a of the second piston 32.
4 are provided. The check valve 34 has the same configuration as the check valve 24 provided on the piston body 22a of the first piston 22.

A third slider 40 is provided in the second tube 31 of the second slider 30. This third
The slider 40 has a slide rod 41 fitted concentrically with the second tube 31 of the second slider 30, and a third piston 42 provided at a lower end of the slide rod 41. The upper end of the slide rod 41 protrudes upward from the upper end surface of the second tube 31, and the elevator body is attached to the upper end. When the third piston 42 slides upward in the second tube 31, the slide rod 41 advances out of the second tube 31 and the third piston 42 slides downward in the second tube 31. , Slide rod 41
And into the second tube 31. A portion of the slide rod 41 projecting upward from the second tube 31 is supported in a sealed state on the inner peripheral surface of the upper end surface of the second tube 31 in the second slider 30.

The hydraulic cylinder having such a structure operates as follows. When pressure oil is supplied into the fixed tube main body 11 through a pressure oil port 13 provided in the bottom portion 12 of the fixed cylinder 10, the first piston 22 of the first slider 20 disposed in the fixed tube main body 11 Slides upwards. Thereby, the first tube 21 having the lower end attached to the first piston 22 slides upward,
It extends upward from the fixed tube main body 11.

At this time, the pressurized oil sealed above the first piston 22 inside the fixed tube main body 11 rises into the cylindrical portion 22b of the first piston 22 as the first piston 22 inside the fixed tube main body 11 rises. The gas flows into the first tube 21 through the provided pressure oil supply / discharge holes 23. As a result, the second tube arranged in the first tube 21
The second piston 32 of the slider 30 slides upward, and the second tube 31 having a lower end attached to the second piston 32 slides upward and extends upward from the first tube 21.

As described above, when the second piston 32 rises, the second piston 32 inside the first tube 21
The pressure oil sealed above flows into the second tube 31 through each pressure oil supply / discharge hole 33 provided in the cylindrical portion 32 b of the second piston 32. Thereby, the second tube 3
The third piston 4 of the third slider 40 disposed in the first piston 4
2 slides upward, and a slide rod 41 having a lower end attached to the third piston 42 slides upward and extends upward from the second tube 31.

By supplying the pressure oil into the lower portion of the fixed cylinder 10, the first slider 20, the second slider 30, and the fourth slider 40 are simultaneously extended upward. As a result, the fourth slider 40
The elevator body attached to the upper end of the vehicle is smoothly lifted at a constant speed.

On the contrary, the fixed tube main body 1 is connected via a pressure oil port 13 provided on the bottom 12 of the fixed cylinder 10.
When the pressure oil in the lower portion of the fixed tube body 1 is discharged,
1st piston 2 of 1st slider 20 arranged in 1
2 slides down. Thereby, the first piston 2
2 has a lower end attached thereto, the first tube 21 slides downward, and the first tube 21 is
Retreat inside.

At this time, the space above the first piston 22 inside the fixed tube main body 11 becomes a negative pressure, and the pressure oil sealed in the first tube 21 is released by the first piston 2.
The fluid flows into the upper portion of the fixed tube main body 11 through the respective pressure oil supply / discharge holes 23 provided in the second cylindrical portion 22b. As a result, the second slider 3 disposed in the first tube 21
The 0 second piston 32 slides downward, and the second tube 31 having the lower end attached to the second piston 32 slides downward and retreats into the first tube 21.

As described above, when the second piston 32 descends, the second piston 32 inside the first tube 21
The space above the third piston 40 becomes a negative pressure, and the pressure oil supplied to the lower part of the third slider 40 is applied to the cylindrical portion 32b of the second piston 32.
And flows into the second tube 31 through each pressure oil supply / discharge hole 33 provided in the second tube 31. As a result, the third piston 42 of the third slider 40 disposed in the second tube 31 slides downward, and the slide rod 41 having the lower end attached to the fourth piston 32 slides downward, and the second piston 32 slides downward.
Retreat into the tube 31.

In any case, the first piston 2
2 and the second piston 3
Each of the pressure oil supply / discharge holes 33 and 3 is provided with an orifice formed by a stepped portion 23a and 33a provided at the center in the axial direction.
The pressure oil passing through 3 is in a state of being throttled by each orifice. As a result, the third piston 42 of the third slider 40 and the second piston 3 of the second slider 30
2 is in a decelerating state and smoothly rises and falls. In addition, the occurrence of cavitation is suppressed in the pressure oil passing through each of the pressure oil supply / discharge holes 23 and 33, and there is no possibility that noise is generated.

Fixed tube body 1 of fixed cylinder 10
1. First tube 21 and second tube 21 of first slider 20
The upper end surface of each of the second tubes 31 of the slider 30 is sealed in a liquid-tight state.
The fixed tube main body 11, the first tube 21, the second tube 3, and the second tube 31 and the slide rod 41 advance and retreat from the upper end surface, respectively.
(1) A part of the pressure oil sealed in each upper part may leak to the outside. As described above, when a part of the pressure oil leaks, even if the slide rod 41, the second tube 31, and the first tube 21 are respectively retracted, the second tube 31, the first tube 21, the fixed tube There is a possibility that air is sucked into the main body 11 from the seal portion. Thus, the second tube 31,
When air is sucked into the first tube 21 and the fixed tube main body 11, the third slider 4
0, the second slider 30 and the first slider 20,
Each of them may cause a malfunction.

In this case, when the first piston 22 is forcibly lowered, the inside of the first tube 21 becomes negative pressure, and the entire valve body 24c is slid upward against the urging force of the compression spring 24e. . Thereby, the through-hole 22c provided in the piston main body 22a is opened, and the pressure oil in the lower end of the fixed tube main body 11 flows into the first tube 24 through the through-hole 22c. Then, the pressure oil in the first tube 24 is supplied into the upper portion of the fixed tube main body 11 through each pressure oil supply / discharge hole 23 provided in the first piston 22.

Similarly, the second piston 32 disposed in the first tube 21 is also forcibly lowered, so that the pressure oil in the first tube 21 passes through the check valve 34 provided on the second piston 32. Is supplied into the second tube 32, and the pressure oil in the second tube 32 passes through each pressure oil supply / discharge hole 33 provided in the second piston 32 and passes through the first tube 21.
Supplied in the upper part.

In this way, the second tube 32 and the first tube 2
2, and the pressurized oil is supplied into the fixed tube main body 11, and the third slider 40, the second slider 30
The first slider 20 and the first slider 20 are not likely to malfunction.

FIG. 3 is a partially cutaway front view showing another example of the embodiment of the hydraulic cylinder of the present invention. In this hydraulic cylinder, the hydraulic cylinder shown in FIG. 1 corresponds to each hydraulic oil supply / discharge hole 2 provided in the first piston 22 of the first slider 20.
The configuration is the same except that only the configuration 3 is different.

At the lower end of the cylindrical portion 22b of the first piston 22, a plurality of pressure oil supply / discharge holes 23 are provided at appropriate intervals in the circumferential direction. Each of the pressure oil supply / discharge holes 23 has a constant inner diameter in the axial direction. The upper end of the opening of the end face of each pressure oil supply / discharge hole 23 located inside the cylindrical portion 22b is covered by the lower end of the first tube 21 inserted into the cylindrical portion 22b. Therefore, the opening of the end face of each pressure oil supply / discharge hole 23 is the first tube 2.
Orifices 2 covered by the lower ends of
3c is formed.

Similarly, each of the pressure oil supply / discharge holes 33 provided in the second piston 32 of the second slider 30 also has a constant inner diameter, and the upper end of the end face opening located in the cylindrical portion 32b is formed in the same manner. Each of the second tubes 31 is covered with a lower end portion to form an orifice.

As described above, the first piston 22 and the second piston 22
Each pressure oil supply / discharge hole 23 and 33 provided in the piston 32
Are provided with orifices, respectively, so that the pressure oil passing through the pressure oil supply / discharge holes 23 and 33 does not pulsate, and therefore, when the first piston 23 and the second piston 33 descend, they smoothly move. The speed is reduced, and the generation of noise due to the generation of cavitation is suppressed.

In order to form the orifices 23c and 33c, the pressure oil supply / discharge holes 23 and 33 do not need to be specially machined on the inner peripheral surfaces thereof, and the lower ends of the first tube 21 and the second tube 31 are not required. The parts can be inserted into the cylindrical part 22b of the first piston 22 and the cylindrical part 32b of the second piston 32, respectively, so that the parts cover the end face openings of the pressure oil supply / discharge holes 23 and 33, respectively. can do.

Since the other configuration of the hydraulic cylinder of the present embodiment is the same as that of the hydraulic cylinder shown in FIG. 1, FIG. 3 shows the same reference numerals as those of the hydraulic cylinder shown in FIG. The description is omitted here.

[0045]

As described above, the hydraulic cylinder of the present invention
When the first slider and the second slider expand and contract at the same time, the pressure oil passing through the pressure oil supply / discharge hole provided in the first slider is throttled by the orifice, so that the occurrence of cavitation is suppressed. Thus, the generation of noise is significantly reduced. In addition, the orifice can be easily manufactured by forming a part of the one end face opening of the pressure oil supply / drainage hole.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing an example of an embodiment of a hydraulic cylinder of the present invention.

FIG. 2 is a sectional view of a pressure oil supply / discharge hole provided in the first piston.

FIG. 3 is a partially broken front view showing another example of the embodiment of the hydraulic cylinder of the present invention.

FIG. 4 is a longitudinal sectional view showing an example of a conventional constant-speed single-acting telescopic cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixed cylinder 11 Fixed tube main body 12 Bottom part 13 Pressure oil port 20 First slider 21 First tube 22 First piston 22a Piston main body 22b Cylindrical part 22c Through hole 23 Pressure oil supply / discharge hole 23a Step 23c Orifice 24 Check valve 24c Valve 24e Compression spring 30 Second slider 31 Second tube 32 Second piston 32a Piston body 32b Cylindrical part 32c Through hole 33 Pressure oil supply / discharge hole 33a Step 33c Orifice 34 Check valve 40 Third slider 41 Slide rod 42 First 3 piston

Claims (3)

[Claims] 1. A hollow cylindrical first slider arranged in a fixed cylinder so as to be slidable in the axial direction, and a second slider arranged in the first slider so as to be slidable in the axial direction. With the supply and discharge of the pressurized oil into the fixed cylinder, the first slider slides in the advance and retreat directions with respect to the fixed cylinder, respectively, and is filled in the fixed cylinder in advance. A hydraulic cylinder in which pressure oil is supplied and discharged into the first slider through a pressure oil supply / discharge hole provided in the first slider, wherein the pressure oil passes through the pressure oil supply / discharge hole. The hydraulic cylinder is characterized in that it is throttled by an orifice. 2. The hydraulic cylinder according to claim 1, wherein the orifice is formed by a step provided to protrude inward inside the pressure oil supply / discharge hole. 3. The hydraulic cylinder according to claim 1, wherein the orifice is configured by closing a part of one end face opening of the pressure oil supply / discharge hole.