JP2003184824A - Piston type single acting cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston type single acting cylinder which can prevent rusting in a chamber on a rod side, and moreover, can smoothly expand and contract without giving a bad influence to a packing or the like with a simple structure. <P>SOLUTION: In the piston type single acting cylinder in which the chamber on the rod side 1a is released to the atmosphere through a communicating port 13 and a rod 3 is made to be freely telescopic by supply of a fluid to a chamber 1b on a piston side and by discharge of the fluid from the chamber 1b on the piston side, the communicating port 13 is blocked so as to seal the rod chamber 1a by a blocking member 14 when the rod 3 is elongated to the maximum. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston-type single-acting cylinder, and more particularly to a loading tray lifting device in which a loading tray is provided on a loading platform of a vehicle so as to be able to move up and down. It is used as an actuator for raising and lowering the table. 2. Description of the Related Art Conventionally, in a piston type single-acting cylinder, a rod side chamber is released to the atmosphere through a communication port, and the rod expands and contracts by supplying hydraulic pressure and the like to the piston side chamber and discharging hydraulic pressure and the like from the piston side chamber. It was done freely. [0003] However, in the above-described conventional single-acting piston type cylinder, if water is attached near the communication port, the water is communicated with the atmosphere when the rod is retracted. There is a problem that the water is sucked into the rod side chamber through the mouth, and this water causes rust to be generated in the rod side chamber. Although the above problem can be solved by connecting the communication port to a tank such as a power unit to block the air from flowing into and out of the atmosphere, an extra pipe for connecting the communication port to the tank is required. There was a problem that the structure became complicated. The present invention has been made in view of the above-mentioned problems, and has as its object to have a simple structure, prevent rust from being generated in the rod side chamber, and have a bad influence on packing and the like. An object of the present invention is to provide a piston-type single-acting cylinder capable of smoothly performing expansion and contraction operations without causing any problem. In the piston type single-acting cylinder according to the first aspect of the present invention, the rod-side chamber is released to the atmosphere through the communication port to supply the fluid to the piston-side chamber and to release the fluid from the piston-side chamber. In the piston type single-acting cylinder in which the rod is made expandable and contractable by discharging the fluid, the communication port is closed by a closing member so as to hermetically close the rod chamber when the rod is fully extended. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a single-acting piston type cylinder according to the present invention. In FIG. 1, reference numeral 1 denotes a cylinder body, and a piston 2 is provided in the cylinder body 1 so as to be able to reciprocate in the axial direction. A proximal end of a rod 3 is connected to the piston 2, and a distal end of the rod 3 is inserted through a scraper 4 from a distal end of the cylinder body 1 to the outside. Therefore, one end side (right side in FIG. 1) of the cylinder body 1 where the rod 3 extends from the piston 2 is the rod side chamber 1a.
The other end (left side in FIG. 1) opposite to the rod 3 across the piston 2 is formed as a piston side chamber 1b. The other end of the cylinder body 1 is provided with a supply / discharge port 11 for fluid such as pressure oil. Supply / discharge port 11
Is connected to the piston side chamber 1b through a supply / discharge passage 12 formed in the cylinder body 1, and is connected to a pressure oil supply source through a pipe (not shown). Accordingly, the piston side chamber 1b is supplied from the pressure oil supply source via the supply / discharge port 11 and the supply / discharge path 12.
By supplying the pressure oil to the
The piston 2 moves inside the cylinder body 1 by moving to the one end side (right side) to extend the rod 3 and discharge the pressure oil from the piston side chamber 1b through the supply / discharge passage 12 and the supply / discharge port 11. Is moved to the other end side (left side), and the rod 3 is retracted. On the other hand, a communication port 13 communicating with the atmosphere is formed on the rod side chamber 1a side, and the communication port 13 is closed by a plug 14 as a closing member. The plug 14 extends the rod 3 to the maximum with the communication port 13 released, and closes the communication port 13 when the rod 3 is in this state to seal the inside of the rod side chamber 1a. I have. By closing the plug 14 in this manner,
When the rod 3 is retracted most, the pressure in the rod side chamber 1a becomes negative, and when the rod 3 is extended most, the pressure in the rod side chamber 1a becomes 0 Pa (gauge pressure). More specifically, depending on the capacity of the cylinder body 1, for example, when the rod 3 is retracted most, the pressure in the rod side chamber 1a becomes a negative pressure of about -0.098 MPa. Therefore, when the rod 3 is most retracted, the scraper 4, the O-ring 5, and the piston packing 6 provided in the cylinder body 1 are in the same state as the external pressure of about 0.098 MPa is applied. With such an external pressure, the scraper 4, the O-ring 5, and the piston packing 6 are not adversely affected, and the damage thereof can be prevented. With this simple structure, when the rod 3 contracts, water is not sucked into the rod side chamber 1a together with the air, and rust can be prevented from being generated in the rod side chamber 1a. On the other hand, when the communication port 13 is closed by the plug 14 when the rod 3 is retracted most, and the rod side chamber 1a is sealed, when the rod 3 is extended most, the rod side chamber 1a is closed. The pressure inside reaches up to several tens of MPa (actually, 0.5 MPa
To the extent that the scraper 4, the O-ring 5, the piston packing 6 and the like are adversely affected. The piston type single-acting cylinder according to the present invention thus configured can be used as an actuator in various fields. Specifically, for example, it can be used as an actuator such as a loading tray lifting device in which a loading tray is provided on a loading platform of a vehicle so as to be able to move up and down. As described above, according to the piston type single-acting cylinder of the present invention, the communication port is closed by the closing member so as to seal the rod chamber when the rod extends to the maximum. With a simple structure, the cylinder can be operated without adverse effects such as damage to the dust seal and O-ring of the cylinder. Therefore, water is not sucked into the rod-side chamber together with the atmosphere when the rod contracts as in the prior art, and rust can be prevented from being generated in the rod-side chamber.
The durability can be improved and the expansion and contraction operation can be performed smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a piston type single-acting cylinder of the present invention. [Description of Signs] 1 Cylinder main body 1a Rod side chamber 1b Piston side chamber 13 Communication port 14 Plug (blocking member) 2 Piston 3 Rod

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiromitsu Kawakami             2-43-3 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa               Shin Meiwa Auto Engineering Co., Ltd.             Inside (72) Inventor Michio Mochizuki             2-43-3 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa               Shin Meiwa Auto Engineering Co., Ltd.             Inside F term (reference) 3H081 AA01 AA03 BB02 BB16 CC08                       CC17 CC24 DD22 DD28 HH03                       HH08

Claims (1)

Claims: 1. A single-acting piston type in which a rod-side chamber is released to the atmosphere through a communication port, and a rod is made expandable and contractable by supplying a fluid to a piston-side chamber and discharging a fluid from the piston-side chamber. In the cylinder, the communication port is closed by a closing member so as to hermetically close the rod chamber when the rod is maximally extended.