JPH04185905A - Hydraulic cylinder in which screw is used - Google Patents

Abstract

PURPOSE:To prevent a piston from being moved due to oil leakage by mounting a screw rod, which is mounted in a cylinder body so that it can be rotated but cannot be moved in axial direction of the rod and screwed into a piston, slidably in a piston rod, and rotating it by a driving device. CONSTITUTION:A screw rod 6 screwed into a piston 5 is mounted in a cylinder body 4 so that it can be rotated through a bearing 7 but cannot be moved in axial direction of the rod, and a cylindrical escape hole 9 is provided in a piston rod 8 to store the screw rod 6. Also the screw rod 6 is connected to an output shaft 14 of a motor 10 through toothed pulleys 11 and 12 and a toothed belt 13. Thus the movement of the hydraulic cylinder 3 can be locked by the screw rod 6 after hydraulic pressure operation is stopped, and the movement of the piston can be prevented to secure safety even if oil leakage occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of a hydraulic cylinder used to drive a lift device or the like.

(Prior art) Conventionally, drive devices used in lifters are small but have large power, so in this case, O-rings as gaskets used inside hydraulic cylinders and hydraulic valves are used. In addition to the risk of oil leaking from the hydraulic cylinder, the hydraulic hose or joint attached to the hydraulic cylinder may be damaged for some reason or due to long-term use. In that case, the oil in the hydraulic cylinder may be damaged. There was a drawback that the lift, which should be in a stopped state, descends due to a decrease in pressure (pressure drop).

As a solution to this problem, there is a cylinder-type drive device that reciprocates a piston integrated with a nut by rotating a threaded rod driven by a motor, and applies a brake to the drive system when it stops, but in this case, the table does not fall due to oil leakage. However, when used in a lifter, the total length of the cylinder is too long for the cylinder stroke, and the screw diameter is large because the thrust is generated by a screw, so the outer diameter is also large.In the end, to generate the same thrust, it is better to use a hydraulic cylinder. The disadvantage was that it could be made much smaller.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic cylinder with screws that can prevent movement of a piston even if oil leaks by using both hydraulic pressure and screws.

(Means for Solving the Problems) The present invention provides a threaded rod between one end of a cylinder body and a piston that reciprocates within the cylinder body; The piston rod is installed so that it cannot be moved in a particular direction and is rotatable, and the other end of the cylinder body is attached so as to protrude and reciprocate with the piston.A relief hole for the threaded rod is formed in the piston rod, and the threaded rod is attached to one end of the cylinder body. There is a hydraulic cylinder with a screw attached to it with a motor to rotate it.

(Function) In the case of forward movement of the piston in a hydraulic cylinder combined with a screw configured as described above, the hydraulic pressure and the motor operation are turned on, the hydraulic cylinder is moved forward, and the motor is rotated in the normal direction corresponding to the forward movement of the piston, and the screw is moved forward. When the rod is controlled in a manner that precedes the piston's feed by hydraulic pressure, the piston moves forward mainly with thrust from the hydraulic pressure, but also with thrust from the rotation of the threaded rod.

Next, when the hydraulic pressure and motor operation are turned off in this forward state, the forward movement of the piston will immediately stop, and if there is an oil leak in this stopped state, it will be the case that conventional hydraulic cylinders and lids are used. Then, the tip of the lifter descends according to the amount of oil leaking.However, in the case of the present invention, the lead of the threaded rod is small, so the table is locked with the threaded rod, so even if oil leaks, the table is locked. Moreover, since the table is supported by a threaded rod, oil leakage is prevented when the table is stopped, and the next table raising/lowering operation can be carried out smoothly.

(Effects of the Invention) As described above, in the case of the present invention, the threaded rod locks the movement of the hydraulic cylinder after hydraulic operation has stopped, so even if there is an oil leak in the hydraulic system, the movement of the piston is prevented and the hydraulic cylinder is stopped. When used as a lid, the table is prevented from being accidentally lowered due to oil leakage, thereby ensuring the safety of workers and the like.

(Example) Next, the configuration of an example of the present invention will be described with reference to the drawings.

A threaded rod 6 is connected between one end of a cylinder body 4 of a hydraulic cylinder 3 used for raising and lowering a table 2 such as a lifter 1 shown in FIG. 1 and a piston 5 that reciprocates within the cylinder body 4.
The piston 5 is screwed into a nut and is rotatably attached to one end of the cylinder body 4 via a bearing 7 or the like so that it cannot move in the axial direction, and is attached with the other end of the cylinder body 4 protruding. A cylindrical relief hole 9 for the threaded rod 6 is formed in the piston rod 8 that reciprocates with the piston 5, and the threaded rod 6 is provided at one end of the cylinder body 4.
Motor for rotating 10. In this case, a motor 10 such as a torque motor that does not burn out even when restrained is attached, and the threaded rod 6 is connected to the toothed pulleys 11 and 12 and the toothed belt 13.
It is connected to the output shaft 14 of the motor 10 via.

In addition, a knuckle 15 is attached to the tip of the piston rod 8 to attach it to the link mechanism for lifting and lowering the table 2 of the lid l.
is attached, and a support ring 16 is attached in the cylindrical relief hole 9 of the piston rod 8 to support the other end of the threaded rod 6 in a slidable and rotatable manner together with the threaded rod 6. h17 and the shifter tube 18 are formed with piping ports 19 for inlet and outlet of pressure oil, and O-rings 20 for sealing are appropriately attached to appropriate locations.

Next, the operation of this embodiment will be explained.

When the lifter 1 is raised and the piston 5 is moved forward in the screw hydraulic cylinder 21 configured as described above, when the motor 10 is first turned on, the motor lO torque is applied to the threaded rod via the toothed pulleys 11X and 12 and the toothed belt 13. However, because the load from table 2 is large,
Since the motor 10 used has a small output that only rotates the threaded rod 6, the threaded rod 6 is not rotated and the motor 10 is restrained.

A few seconds after turning on the motor 10, the cylinder tube 1
When pressure oil is fed into the piston rod 8 by a pump (not shown), the feed speed of the threaded rod 6 is set faster than the moving speed of the piston 5, so the piston rod 8 moves forward in the same state as normal hydraulic operation. , at this time, the threaded rod 6 is connected to the piston 5
3, the threaded surface of the threaded rod 6 and the threaded surface of the piston 5 come into contact as shown in FIG. 3, and the thrust of the hydraulic cylinder 3 is generated by hydraulic pressure.

Next, when the hydraulic pressure and the operation of the motor 10 are turned off in this forward state, the forward movement of the piston 5 immediately stops.If oil leaks in this stopped state, conventionally, this hydraulic cylinder is used as a lifter. In this case, the table 2 of the lifter is lowered according to the amount of oil leakage, or in the case of the present invention, the lead of the threaded rod 6 is small, so the table 2 is locked with the threaded rod 6. Even if there is an oil leak, it will not descend, and in addition, the threaded rod 6
Because the table 2 is supported by the table 2, oil leakage is prevented when the table 2 is stopped, and the next movement of raising and lowering the table 2 can be performed smoothly. At times, only the thrust generated from the torque of the motor 10 is received, so a screw with a small diameter can be used; However, since this load is a static load, the contact stress on the threaded surface can be large, so the threaded rod 6 can be a small-diameter screw.

Next, when the lifter 1 is lowered and the piston 5 is operated backward, the threaded surface of the threaded rod 6 and the threaded surface of the piston 5 are in contact as shown in FIG. However, since the piston 5 does not move even if the motor 10 is reversed, pressurized oil is fed into the cylinder tube 18 for a short period of time with the motor 10 stopped so that the motor 10 is in the state shown in FIG. When the motor 10 is rotated in the opposite direction (the feeding speed of the threaded rod 6 is set faster than the moving speed of the piston 5), the threaded rod 6 does not rotate and the motor 10 is suspended. 2. Name of the invention: Hydraulic cylinder with screw combination 3. Relationship with the person making the amendment: Patent applicant Address: 180 Higashi, Inukuden-cho, Toyoake City, Aichi Prefecture Name: Meiki Co., Ltd. (Name) Representative: Address: 1 ) Atsushi 4, Agent address: 2-10-1 Sakae, Naka-ku, Nagoya 460
No. 9 Nagoya Chamber of Commerce and Industry Building January 28, 1991 (Shipped February 12, 1991) 6. It is in a bundle subject to correction.

After this operation, if the pressure oil in the cylinder tube 18 is immediately drained, the piston 5 will descend in the state shown in FIG. The lowering operation is completed, and the lifter 1 remains locked by the threaded rod 6 as described above.

In this way, in the case of this threaded hydraulic cylinder 21, the threaded rod 6 locks the movement of the hydraulic cylinder 3 after hydraulic operation is stopped, so even if there is an oil leak in the hydraulic system, the movement of the piston 5 is prevented. When the hydraulic cylinder 3 is used in the lifter L, it is possible to prevent the table 2 from inadvertently lowering due to oil leakage, and to ensure the safety of workers, etc. There are also advantages such as the pressure oil also serving as lubricating oil.

[Brief explanation of drawings]

Fig. 1 is a front view of a road body showing the usage state of an embodiment of the present invention, Fig. 2 is a detailed cutaway view of the screw-combined hydraulic cylinder 21, and Figs. 3 and 4 are main parts showing its operating state. It is a detailed view. 3: Hydraulic cylinder 4 Cylinder body 5 Piston 6. Threaded rod 7: Bearing 8: Piston rod 9/cylindrical escape hole 10, Motor

Claims (1)

[Claims] A threaded rod is attached between one end of the cylinder body and a piston that reciprocates within the cylinder body, and the piston is screwed into a nut, and is attached to one end of the cylinder body so that it cannot move in the axial direction but is rotatable. A piston rod that is attached with the other end of the cylinder body protruding and reciprocates with the piston has an escape hole for the threaded rod, and a drive device for rotating the threaded rod is attached to one end of the cylinder body. Hydraulic cylinder with screw.