JPS61167704A - Hydraulic cylinder enabled to change acting force - Google Patents

Abstract

PURPOSE:To change a telescopic speed and acting force, by placing a control rod telescopically extending and retracting in a piston rod housed in a hollow cylinder. CONSTITUTION:If oil is injected into a cylinder 21 from a port 24, a piston rod 29 is pulled out from a cylinder top 23 by pressing a piston 28. Here the piston rod 29 moves at a quick speed with a control rod 30 generating no movement in the cylinder 21. Next, if oil is injected into a holding hole 26 from a port 27, the oil in the cylinder 21, circulating through a passage 32, extrudes the control rod 30 with no load being applied, and if a bottom end of the control rod 30 is drawn out from the holding hole 26, the piston 28 is closely attached to a control piston 31. In this way, an oil hydraulic cylinder, integrally moving the piston 28, piston rod 29, control rod 30 and the control piston 31 in the cylinder 21 and increasing force by fluid acting on the piston rod 29, is enabled to increase acting force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to hydraulic application equipment, and particularly to a hydraulic cylinder whose operating force can be changed so that the operating speed and operating stress of a piston rod can be varied.

[Conventional technology]

A hydraulic cylinder is known as a mechanism that operates in a linear direction using hydraulic pressure generated by a hydraulic pump or the like, and this hydraulic cylinder is widely used in construction machinery, vehicles, jacks, machine tools, and the like. This hydraulic cylinder is formed from an internally hollow cylinder body and a piston rod that is slidably inserted into the cylinder body, and the operating speed and operating stress are set by the internal cross-sectional area of the cylinder body. It was something.

[Problem that the invention seeks to solve]

As mentioned above, the internal cross-sectional area of the cylinder body is determined at the time of manufacture, and therefore, this cross-sectional area cannot be changed once it is incorporated into equipment or assembled into a machine. For this reason, if you want to change the capacity of a hydraulic cylinder, you must either increase the number of hydraulic pressures supplied or increase the hydraulic pressure. was something that had been decided. For this reason, the capacity of the hydraulic cylinder is automatically determined at the design stage, and if you want to change the new capacity when operating the device, you will have to change the hydraulic pump, which is almost impossible in reality. Met.

Means for Solving Problem c] A cylinder having a hollow interior, a piston rod housed within the cylinder and sliding thereon, a sliding space formed within the piston rod along the direction of movement of the piston rod, and a sliding space formed within the piston rod along its moving direction. To provide a hydraulic cylinder capable of changing operating force, characterized in that it is configured with a control loft that can slide in close contact with a space and that moves in and out of an internal space within the cylinder to vary an operating cross-sectional area with respect to a piston rod. It is.

[Effect]

Pressure oil from a hydraulic pump is supplied into the space formed by the cylinder and piston rod, and the piston slides within the cylinder. However, if the piston rod is to move at a faster speed, the control rod must be moved inside the cylinder. It is brought into contact with one end to reduce the contact area of the hydraulic oil. Further, in order to increase the output stress by the piston rod, it is possible to move it toward the control rod side to increase the cross-sectional area to which pressure oil is applied, thereby increasing the output of the piston rod.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, an example in which the present invention is applied to an aerial work vehicle will be explained. A front wheel 2 and a rear wheel 3 are pivotally supported on the front, rear, left, and right sides of the vehicle body 1, allowing the vehicle body 1 to move freely.The lower part of the vehicle body 1 contains a power source housing the engine, hydraulic pump, etc. Box 4 is for installation.

A pair of shaft support pieces 5 are fixed to one end of the upper surface of the vehicle body 1 at intervals, and a lower poom 6 having a hollow interior with a square cross section is inserted between the shaft support pieces 5. The piece 5 and the lower boom 6 are rotatably connected by a pin 7. A pair of pins 8 are fixed to the left and right sides of the upper surface of the vehicle body 1 at positions opposite to the shaft support pieces 5, and between the pins 8 and the outside of the lower boom 6, there is a A hydraulic cylinder 9 is interposed. The tip of the lower boom 6 has a rectangular opening, into which a hollow hollow poom 10 with a square cross section is slidably inserted, and from the tip opening of the middle boom 10, a hollow poom 10 with a square cross section is inserted into the opening. The hollow end boom 11 is slidably inserted therethrough. The tip of the tip boom 11 is inserted into an internally hollow lifting pool 12 having a rectangular cross section. Equally spaced gaps are formed between them. The upper and lower outer booms 6 and 12 are each set to have a length approximately half the length of the vehicle body 1, and the middle boom 10 and the tip boom 11 are each set to approximately the same length as the vehicle body 1. Lower boom 6, middle boom 10, front boom 11,
A telescopic boom body 13 is formed by the lifting poom 12 . Reference numeral 16 denotes a flat lifting platform having almost the same floor area as the vehicle body 1. A pair of shaft supporting pieces 14 are fixed to one end of the lower surface of the lifting platform 16 at intervals. A lifting boom 12 is inserted between them, and the shaft support piece 14 and the lifting boom 12 are rotatably connected by a pin 15. Further, a pair of pins 17 are fixed to each side of the lower surface of the lifting platform 16 at a position opposite to the shaft support piece 14, and between each pin 17 and both sides of the lifting boom 12, there is a horizontal A hydraulic cylinder 18 for position correction is interposed, and a handrail 19 is installed around the upper surface of the lifting platform 16.

Next, FIG. 5 shows the inside of the above-mentioned hydraulic cylinder 9. The outer periphery of the hydraulic cylinder 9 is formed from a cylinder tube 21 which is hollow inside and has a cylindrical shape.
One end of the cylinder 1 is closed by a cylinder bottom 22, and the other end is provided with a cylinder head 23 having an opening having a diameter smaller than the inner diameter of the cylinder tube 21. An operating port 24 and a return port 25 are provided at both side ends of the cylinder tube 21, and a holding hole 26 with a small inner diameter is formed at the center of the cylinder bottom 22 on the side facing the cylinder tube 21. A control port 27 is formed at the back of the holding hole 26. A piston 28 having an annular shape and having a penetrating center is inserted into the cylinder tube 21. A piston rod 29 having a hollow pipe shape inside is connected to the piston 28. It protrudes to the outside through the opening of the head 23. A cylindrical control rod 30 is slidably inserted into the piston loft 29, and one end of the control rod 30 is configured to be retractable into the aforementioned holding hole 26. and piston 28 are airtightly sealed. Slightly above the lower end of this control rod 30 is formed a large diameter control piston 31 whose outer diameter is approximately the same as the inner diameter of the cylinder tube 21 and which slides airtightly. The control piston 31 is formed with a passage 32 that communicates between the upper and lower sides, and an O-ring 33 that contacts the control loft 30 is provided in the holding hole 33. An oil boat 34 is formed in communication with the oil passage boat 34 .

Further, FIG. 6 shows a hydraulic circuit for use in the hydraulic cylinder 9 of this embodiment.

A hydraulic pump 42 is connected to an oil tank 41 that holds pressure oil, and three switching valves 43 and a solenoid valve 44 are connected to the discharge side of the hydraulic pump 42. The operating port 24 is connected to one side of the switching valve 43 via a pressure control circuit 45, and one side of the hydraulic cylinder 18 is connected to the return boat 25 via a pressure control circuit 46. The other end is connected to the switching valve 43. Further, a control boat 27 is connected to the solenoid valve 44, and a control switch 47 is connected to the solenoid valve 44. The oil passing boat 34 is connected to an oil tank 41 through a drain 48.

Next, the operation of this embodiment will be explained.

Figures 2 and 3 show the lifting platform 1 with the lifting boom body 13 scaled down.
6 is lowered to the lowest position. In this state, a worker gets on the lifting platform 16, materials are placed thereon, and the lifting platform 16 is raised. In order to raise the lifting platform 16, the engine in the work box 4 is operated to generate hydraulic pressure, and the hydraulic pressure is supplied to each hydraulic cylinder 9, 18 and the hydraulic cylinder in the telescopic boom 13, respectively.
When hydraulic pressure is supplied to the hydraulic cylinder in the telescopic boom 13, the middle boom 10 is slid and pulled out from the lower boom 6, and the front boom 11 is slid and pulled out from the middle boom 10, thereby reducing the distance between the pins 7 and 15. Expand. Also, by expanding the hydraulic cylinder 9, the pin 7 becomes the center.
; to rotate the lifting poom 6 and lift the telescopic boom body 13 so as to tilt it with respect to the vehicle body l. Telescopic boom 1 due to the extension speed of the telescopic boom body 13 and the hydraulic cylinder 9
When the tilting speed of 3 is synchronized, the bin 15 of the lifting pool 12
rises perpendicularly to the vehicle body 1.

In addition, the lifting platform 16 rotates around the bin 15 due to the extension force of the hydraulic cylinder 18, causing the upper boom 12 and the lifting platform 16 to rotate.
act to expand the angle of hydraulic cylinders 9 and 1.
By synchronizing the extension amount of 8, the lifting platform 16
The vehicle body 1, the telescopic boom 13, and the lifting platform 16 are formed in a two-shape when viewed from the side. Once the platform 16 has risen to a predetermined height, the worker stops the operation of each hydraulic cylinder, and the platform 16 is held at that height, allowing assembly, repair, painting, etc. It can be performed.

Next, to explain the operation of the hydraulic cylinder 9, the state shown in FIG.
The lower surface of the cylinder bottom 22 is in close contact with the inner surface of the cylinder bottom 22.

In this normal state, the switching valve 43 is turned on in the forward direction, and the hydraulic control circuit 45 is connected to the cylinder tube 21 from the operating boat 24.
When hydraulic pressure is supplied to the piston 28, the piston 28 is pushed upward in the figure by the pressure, and the piston loft 29 is pulled out from the cylinder top 23. cylinder tube 21
As the piston 28 moves within the cylinder tube 2
The pressure oil in the upper space of 1 is pushed out from the summer report 25, is supplied to the hydraulic cylinder 18 via the pressure control circuit 4G, and expands the hydraulic cylinder 18. Hydraulic cylinder 1
Pressure oil discharged from 8 returns to oil tank 4 via switching valve 43. Hydraulic cylinder 9 in this state
This operation occurs when the piston loft 29 expands and contracts at a high speed, and the pressure oil input from the operating port 24 is applied to the annular cross-sectional area defined by subtracting the outside diameter of the control rod 30 from the inside diameter of the cylinder tube 21. control rod 3
0 does not move within the cylinder tube 21 and the piston 2
8. Only the piston loft 29 moves, and its movement speed is faster than that of a conventional hydraulic cylinder with a piston tube 21 of the same inner diameter.

Next, when the load mounted on the lifting platform 16 becomes heavy, the output of the hydraulic cylinder 9 must be increased to forcefully lift the telescopic boom body 13. In this case, the control switch 47 is pressed and the electromagnetic The valve 44 is made conductive and the pressure oil from the hydraulic pump 42 is transmitted to the control port 27 to control the control rod 30 to be pushed out from the holding hole 26. 7th
The figure shows that pressure oil is applied into the holding hole 26 and the control rod 30
The figure shows the state in the middle of being pulled out from the holding hole 26. Pressure oil inside the cylinder tube 21 flows through the flow path 32.
The control loft 30 is unloaded due to the flow through the
The pressure inside the holding hole 26 pushes it toward the cylinder loft 29 . When the lower end of the cylinder loft 30 is pulled out from the holding hole 26, it is still pushed in the direction of the piston loft 29 by the pressure inside the cylinder tube 21, so that the piston 28 and the control piston 30 are finally moved as shown in FIG.
are in close contact with each other, and the piston 28, piston loft 29, control rod 30, and control piston 31 slide together in the cylinder tube 21. In the state shown in FIG. 8, the pressure oil injected from the operating port 24 is
, control rod 30, and pressurized oil is applied to the front cross-sectional area of the inner diameter of the cylinder tube 21, so that the piston rod 29 increases its output and expands.

When the piston rod 29 of the hydraulic cylinder 9 is pushed into the cylinder tube 21 to shorten its overall length, the switching valve 43 is reversed to transmit pressure oil from the hydraulic pump 43 to the hydraulic cylinder 18.

Pressure oil discharged from the hydraulic cylinder 18 is transferred to the cylinder tube 21 from the return port 25 via the pressure control circuit 46.
, and pushes down the piston 28, causing the piston 28, piston rod 29, control rod 30, and control piston 31 to slide downward within the cylinder tube 21 and shorten their length. Pressure oil in the space below the cylinder tube 21 returns to the oil tank 41 from the operating port 24 via the pressure control circuit 45 and the switching valve 43.

When the piston 28 moves to the lowest position, the control rond 3
The lower end of 0 is pushed into the holding hole 26 and returns to the state shown in FIG.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to vary the expansion and contraction speed of the piston rod according to the purpose of the hydraulic cylinder's operation, and it has wider applicability than conventional hydraulic cylinders that can only be expected to operate in a simple manner. It is what it is.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an aerial work vehicle showing an embodiment of the present invention;
Figure 2 is a side view of the same as above with the height lowered, Figure 3 is a front view of the same as above, Figure 4 is a side view of the same as above with the height extended, Figure 5 is a sectional view of the hydraulic cylinder. , Fig. 6 is a hydraulic circuit diagram, and Figs. 7 and 8 are explanatory diagrams showing the operating states of the hydraulic cylinders. 9... - Hydraulic cylinder, 21... Cylinder tube, 28...・-Piston, 29--Piston loft, 30--Control loft, 31...-
control piston. Patent applicant Hikoma Manufacturing Co., Ltd. Agent
Patent Attorney Akira Hibi Figure 2 Figure 4 Figure 5 Figure 7 Figure 8 Procedural Dispute Manual (spontaneous) February 20, 1985 1, Indication of Case 1985 Patent Application No. 8019 2 , title of the invention 3, person making the amendment 4, agent

Claims (1)

[Claims] A cylinder that is hollow inside, a piston rod that is housed in the cylinder and slides, a sliding space formed in the piston rod along the direction of movement of the piston rod, and a cylinder that can slide in close contact with this sliding space. A hydraulic cylinder capable of changing operating force, comprising a control rod that appears and retracts from the internal space of the cylinder to vary the operating cross-sectional area with respect to the piston rod.