JPH11294409A - Hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent efficiency while operating a hydraulic pump as a motor from degrading without increasing capacity of the hydraulic pump even if the stroke becomes long by slidably combining together the hollow round bar fixedly erected on a cylinder bottom with a packing provided inside the stopper of a ram bottom part. SOLUTION: The hollow round bar 6 fixedly elected on the cylinder bottom 1b of a hydraulic cylinder slidably combined with a packing 7 provided inside the stopper 2a of a ram bottom part to constitute the hydraulic cylinder. In this case, when oil is fed from an oil feed port 1a, the outer circumferential part of a ram 2 is slidably moved inside a bush 5 and a packing 4, and simultaneously while the packing 7 inside the stopper 2a of the ram 2 bottom part is slidably moved the outer circumference of the hollow round bar 6, the ram 2 is elevated to elevate a weight 9. Consequently, even when the stroke of the ram 2 becomes considerably long and the outer diameter of the ram 2 is enlarged, the oil quantity corresponding to the outer diameter of the hollow round bar 6 can be reduced, and oil pressure can be raised.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic cylinder.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory diagram of a hydraulic cylinder and a control circuit thereof according to a conventional technique. In FIG. 3, the hydraulic cylinder 50 is generally called a ram cylinder. Its main components are cylinder tube 51, cylinder head 53,
It comprises a ram 52 and a packing 54. The ram 52 is slidably mounted on a bush 55 and a packing 54 provided in the cylinder head 53, and the ram 52 moves upward by supplying hydraulic oil from a port 52a, and is fixed to an upper portion of the ram 52. The weight 58 attached to the mounting table 52b can be lifted. By discharging the hydraulic oil from the port 52a, the ram 52 descends. Stopper at the bottom of the ram 52
52a is fixed, and the lower surface thereof is the cylinder bottom 51b.
The amount of movement of the ram 52 from the position where it adheres to the lower end 53a of the cylinder head 53 until the upper surface of the stopper 52a adheres is called the stroke of the hydraulic cylinder 50.

Next, the control circuit 60 of the hydraulic cylinder 50 will be described. The hydraulic pump 65 is driven by an electric motor 64, and is supplied from a hydraulic oil tank 61 through a strainer 62 and a pipe 63. Supply to 50 ports 51a. Accordingly, the ram 52 rises, and the weight 58 also rises. weight
When lowering 58, the solenoid valve 70 is operated to switch to the D position, so that the pressure of the hydraulic oil in the hydraulic cylinder 50 is changed from the pipe 69 to the control valve 67 via the pipes 71 and 72 to the B level.
To the hydraulic pump 65 via the pipe 66. The hydraulic pump 65 rotates as a hydraulic motor when pressured hydraulic oil comes from a pipe 66, and the passed hydraulic oil returns to a hydraulic oil tank 61 via a pipe 63 and a strainer 62. Hydraulic pump 65
When the motor rotates as a hydraulic motor, the electric motor 64 generates power and can return power, so the control circuit 60 is an effective control circuit for energy saving.

[0004]

However, when the stroke becomes considerably long, the outer diameter of the ram needs to be considerably large in order to maintain a constant buckling safety factor in consideration of the buckling strength of the ram. is there. Problems caused by increasing the outer diameter of the ram include: (1) The amount of hydraulic oil supplied to the hydraulic cylinder increases,
Therefore, a large capacity hydraulic pump is required. (2) The hydraulic pressure of the hydraulic oil to be supplied becomes low, so that when the ram is lowered, the efficiency of rotating the hydraulic pump as a hydraulic motor becomes poor, and the energy saving is reduced. And so on.

[0005]

Therefore, according to the present invention, even if the outer diameter of the ram is increased in buckling strength with a hydraulic cylinder having a considerably long stroke, the amount of hydraulic oil does not increase so much. An object of the present invention is to provide a hydraulic cylinder that does not increase the capacity of the pump and does not cause a decrease in efficiency when rotating the hydraulic pump as a hydraulic motor when lowering the ram. As means therefor, a bush and a packing provided on the cylinder head are slidably combined inside a cylinder tube comprising a tube having an oil supply pump, a cylinder bottom fixed to one end of the tube and a cylinder head fixed to the other end. In a hydraulic cylinder composed of a tubular ram, a hollow round bar fixed to the cylinder bottom is erected, and the hydraulic cylinder is slidably combined with a packing provided inside a stopper at the bottom of the ram.

[0006] The present invention has a configuration as described above,
The operation will be described below. Now, when raising the ram, if the required oil amount Q of the working oil is the ram rising amount, that is, the stroke is S, the outer diameter of the ram is D, and the outer diameter of the hollow round bar is d, The amount of oil corresponding to the outer diameter of the hollow round bar can be reduced. In addition, the pressure P of the hydraulic oil at this time is as follows, where the weight of the weight lifted by the ram is W and the resistance loss of the packing or the like is ignored. The pressure corresponding to the outer diameter of the hollow round bar increases. As can be seen from the above description, even if the outer diameter of the ram is increased in terms of the buckling safety factor due to the considerably long stroke of the ram,
By using a hollow round bar having an appropriate outer diameter, it is possible to prevent the oil flow of the working oil from increasing so much and to prevent a decrease in the oil pressure. The reason why the hollow round bar is used is that the hydraulic oil leaked from the packing that seals between the ram and the hollow round bar is drained from the hollow portion.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is an explanatory view of the present invention, and FIG.
FIG. In FIG. 1, a bush 5 provided on the cylinder head 3 is provided inside a cylinder tube 10 comprising a tube 1 having an oil supply port 1a, a cylinder bottom 1b fixed to one end of the tube 1, and a cylinder head 3 fixed to the other end. And a hydraulic cylinder comprising a tubular ram 2 slidably combined with a packing 4, a hollow round bar 6 fixed to the cylinder bottom 1 b is erected, and a packing 7 provided inside a stopper 2 a at the bottom of the ram 2. Hydraulic cylinder slidably combined. When raising the weight 9 attached to the upper part of the ram 2, the outer peripheral portion of the ram 2 is supplied with the pressurized hydraulic oil from the oil supply port 1 a, so that the bush 5 and the packing 4 , And at the same time, the ram 2 rises while the packing 7 inside the stopper 2a at the bottom of the ram 2 slides on the outer periphery of the hollow round bar 6 fixed to the cylinder bottom 1b. When lowering the weight 9, the hydraulic oil may be discharged from the oil supply port 1a.

By using the hydraulic cylinder according to the present invention, even if the stroke is considerably long even in the control circuit according to the prior art, the ram is buckled to maintain a constant buckling safety factor in consideration of the buckling strength of the ram. Even if the outer diameter is increased, (1) an increase in the amount of hydraulic oil supplied to the hydraulic cylinder can be prevented, so that the hydraulic pump does not need to have a large capacity. (2) It is possible to prevent the oil pressure of the working oil to be supplied from being lowered, so that the efficiency of rotating the hydraulic pump as a hydraulic motor when lowering the ram is not deteriorated, and the energy saving effect can be secured. And so on.

[0009]

According to the present invention, a bush and a packing provided on a cylinder head are provided inside a cylinder tube comprising a cylinder bottom fixed to one end of the tube and a cylinder head fixed to the other end of the tube. A hydraulic cylinder comprising a tubular ram slidably combined with a hydraulic cylinder comprising a hollow round bar fixed to the cylinder bottom and slidably combined with a packing provided inside a stopper at the bottom of the ram. If the stroke becomes quite long,
Considering the buckling strength of the ram, even if the outer diameter of the ram is increased to maintain a constant buckling safety factor, an increase in the amount of hydraulic oil supplied to the hydraulic cylinder can be prevented, and therefore the hydraulic pump capacity Does not need to be large, and it is possible to prevent the oil pressure of the working oil to be supplied from lowering.Therefore, when lowering the ram, the efficiency of rotating the hydraulic pump as a hydraulic motor does not deteriorate and the energy saving effect can be secured. Its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is a view as seen from the direction of arrows PP in FIG. 1;

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 1a Oil supply port 1b Cylinder bottom 2 Ram 2a Stopper 3 Cylinder head 4 Packing 5 Bush 6 Hollow round bar 7 Packing 10 Cylinder tube

Claims (1)

[Claims] 1. A bush and a packing provided on a cylinder head are slidably mounted inside a cylinder tube comprising a tube having an oil supply port, a cylinder bottom fixed to one end of the tube, and a cylinder head fixed to the other end. A hydraulic cylinder comprising a combined tubular ram, wherein a hollow round bar fixed to the cylinder bottom is erected and slidably combined with a packing provided inside a stopper at the bottom of the ram.