JPS5836206B2 - Hydraulic cylinder with axial stress detection device - Google Patents

Description

[Detailed Description of the Invention] Accurately measuring the axial force acting on a hydraulic cylinder is necessary to know the safety limits of a device that uses a hydraulic cylinder to move heavy objects, such as a lift device. However, in this type of measurement, a method is generally used in which the oil pressure generated in a hydraulic cylinder is measured as a parameter.

However, the method of measuring the hydraulic pressure generated in a hydraulic cylinder as a parameter has not been able to accurately measure it due to the influence of sliding resistance between the cylinder tip and the outer peripheral surface of the piston rod or the inner peripheral surface of the cylinder.

The present invention relates to a hydraulic cylinder having an axial stress detection device, and aims to provide a hydraulic cylinder that can measure axial stress with extremely high accuracy.

The invention will be explained in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a double-acting hydraulic cylinder, and the double-acting hydraulic cylinder 1 is connected to a cylinder 2, a piston rod 3 slidably fitted in an oil-tight manner to the tip of the cylinder 2, and a piston rod 3 to the base end of the piston rod 3. It consists of a piston 6 which is arranged and slidably fitted into the inner periphery of the cylinder 2 in an oil-tight manner to divide the inside of the cylinder 2 into an oil chamber 4 on the proximal end side and an oil chamber 5 on the distal end side.

7 supplies hydraulic oil to the base end side oil chamber 4 or the base end side oil chamber 4
8 is a supply/discharge port that discharges hydraulic oil from the tip side oil chamber 5 or supplies hydraulic oil to the tip side oil chamber 5, and supplies hydraulic oil to the supply/discharge port 7. At the same time, the piston rod 3 of the double-acting hydraulic cylinder 1 is extended by discharging the hydraulic oil from the supply/discharge port 8,
By supplying hydraulic oil to the supply/discharge port 8 and discharging hydraulic oil from the supply/discharge port 7, the double-acting hydraulic cylinder 1
This is to reduce the size of the piston rod 3.

Reference numeral 9 denotes a cylinder-side fulcrum bracket arranged at the base end of the cylinder 2.

Reference numeral 10 denotes a strain detection member having a central condylar portion 11 and a bracket 12 for a fulcrum on the piston rod side disposed at its tip, which can be removed by screwing its base end into the inside of the tip of the piston rod 3. Possible to bond firmly.

In this connection, the strain detection member 10 is finished to have the same diameter as the piston rod 3 and is located inside a cylindrical extension member 14 that serves as an extension of the piston rod 3 and forms an oil-tight sliding portion with the cylinder 2. It protrudes from the tip of the extension member 14 and is connected to the piston rod 3.

A strain gauge 13 is attached to the central condylar portion 11 of the strain detection member 10 and converts the strain in the central neck portion 11 of the strain detection member 10 into an electrical signal.

Then, the signal electrically converted by the strain gauge 13 is taken out to the bracket 12 side by a conductor, and
The force in the axial direction acting on the hydraulic cylinder 1 is known by electrically processing it.

The hydraulic cylinder 1 configured as described above can electrically convert and extract the strain of the strain detection member 10 corresponding to the stress in the axial direction of the hydraulic cylinder 1 using the strain gauge 13, so that this electric output signal can be extracted. By electrically processing, the axial stress acting on the hydraulic cylinder 1 can be detected extremely accurately.

In the above embodiment, when the strain detection member 10 is coupled to the tip of the piston rod 3, the strain detection member 10 is
The bracket 12 is located inside a cylindrical extension member 14 which is finished to have the same diameter as the piston rod 3 and constitutes an oil-tight sliding portion with the cylinder 2 as an extension of the piston rod 3, and the bracket 12 protrudes from the tip of the extension member 14. However, the strain detection member 10 may be connected to the tip of the piston rod 3 as shown in FIG. 2 or 3.

That is, as shown in FIG. 2, the tip of the piston rod 3 is finished to have the same diameter as the piston rod 3.
A cylindrical extension member 14 that forms an oil-tight sliding portion with the tip of the cylinder 2 is welded as an extension of the strain detection member 10.
The proximal end of the extension member 14 may be screwed into the extension member 14 so that the strain detection member 10 is located inside the extension member 14 and the bracket 12 protrudes from the distal end of the extension member 14. As shown in FIG. 3, a hollow cylindrical mounting member 15 is screwed and attached to the inside of the tip portion of the piston rod 3, and the base end of the strain detection member 100 is screwed to the inside of the attachment member 15 to form the strain detection member. They may be connected so that the bracket 10 is located inside the mounting member 15 and inside the piston rod 3, and the bracket 12 projects from the tip of the mounting member and also from the tip of the piston rod 3.

In the embodiments shown in FIGS. 1 to 3 above, the strain detection member 1
0 to the tip of the piston rod 3, the strain detection member 10 is connected to the piston rod 3 or the piston rod 3.
The outer peripheral surface of the piston rod 3 surrounding the strain detection member 10 or the cylindrical extension member 14 provided at the tip of the piston rod 3 is surrounded by a cylindrical extension member 14 provided at the tip, and the piston rod 3 surrounding these strain detection members 10 is connected to the oil between the piston rod 3 and the cylinder 2. Although the strain detection member 10 is formed in a tight sliding portion, when configured in this way, the strain detection member 10
Since the mounting portion can also be used as an oil-tight sliding portion with the tip of the cylinder 2, the total length of the hydraulic cylinder 1 to which the strain detection member 10 is attached can be made as small as possible.

In other words, when the hydraulic cylinder of the present invention is arranged between two points having a certain distance, it is possible to obtain the same expansion and contraction stroke as a normal hydraulic cylinder without the strain detection member 10 attached. Furthermore, since the strain detection member 10 is surrounded by the outer circumferential wall of the piston rod, it has the excellent effect of being protected from physical damage.

A hydraulic cylinder having an axial stress detection device according to the present invention, even if it falls down, has a strain detection member having a piston rod-side fulcrum at its tip, the proximal end of which is removably fixed to the piston rod tip of the hydraulic cylinder. Since a strain gauge is attached to this strain detection member, the strain in the strain measurement member corresponding to the axial stress of the hydraulic cylinder can be electrically converted and extracted by the strain gauge, so this electrical output signal can be obtained. The axial stress acting on the hydraulic cylinder can be determined extremely accurately by electrical processing, and its effectiveness is extremely significant.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of a hydraulic cylinder embodying the present invention, and FIGS. 2 and 3 are explanatory cross-sectional views of the tip of a piston rod of a hydraulic cylinder showing other embodiments. Piston rod side fulcrum...12, strain detection member...10, piston rod...3, strain gauge...13.

Claims (1)

[Claims] 1 Detection of axial stress by removably fixing the base end of a strain detection member having a piston rond side fulcrum at the tip to the piston rond tip of a hydraulic cylinder, and attaching a strain gauge to this strain detection member. Hydraulic cylinder with device