CN108895060A - A kind of built-in stroke measurment hydraulic cylinder - Google Patents

Abstract

The invention relates to a built-in stroke measuring hydraulic cylinder, which is characterized in that it comprises a wire encoder, an encoder bracket, a cylinder bottom, a cylinder barrel, a wire protection tube, a piston, a piston rod, a cylinder cover, a wire fixing pin and a screw plug; The cylinder bottom and the cylinder cover are respectively arranged at both ends of the cylinder barrel, and the piston is arranged inside the cylinder barrel; there is a cable through hole in the piston rod, and the front end of the piston rod is fixedly connected with the piston; there is a rodless oil inlet hole on the cylinder bottom, There is a rod oil inlet hole on the cylinder head; one end of the cable protection tube extends into the cable through hole of the piston rod, the encoder bracket is fixedly installed on the bottom of the cylinder, the cable encoder is set on the encoder bracket, and the cable encoder The backguy stretches into the backguy through hole of the piston rod through the backguy protection tube and is stuck on the end face of the piston rod rear end with the backguy fixing pin and is fixedly arranged on the piston rod rear end by the screw plug. The invention has the advantages of small required installation space, convenient maintenance and good cost performance.

Description

A built-in stroke measuring hydraulic cylinder

technical field

The invention relates to a hydraulic cylinder, in particular to a built-in stroke measuring hydraulic cylinder.

Background technique

In recent years, with the wide application of hydraulic technology, hydraulic cylinders have become more and more widely used. The hydraulic cylinders used in some high-end servo and proportional hydraulic systems usually need to measure the movement stroke of the hydraulic cylinder to achieve the purpose of actively controlling the movement of the hydraulic cylinder.

The stroke of a hydraulic cylinder is usually measured using a displacement sensor. According to the different installation methods of the displacement sensor, it can be divided into two types: external type and built-in type. The external displacement sensor is installed outside the hydraulic cylinder, and is usually fixed parallel to the side of the hydraulic cylinder, and its measuring moving parts are connected with the exposed part of the piston rod of the hydraulic cylinder. The movement of the piston rod of the hydraulic cylinder drives the moving parts of the displacement sensor to measure the stroke of the piston rod. External displacement sensors include linear potentiometers, differential transformers, inductive synchros, linear gratings, etc. The external displacement sensor has the advantages of low price and convenient installation and maintenance. The disadvantages are low precision, large installation space and easy damage. Different from the external displacement sensor, the built-in displacement sensor is usually fixed on the cylinder bottom of the hydraulic cylinder, and its moving parts are built in the hydraulic cylinder, so the installation space is small; because its moving parts are built in the hydraulic cylinder, and the hydraulic cylinder Non-contact, so not easily damaged. The built-in displacement sensor is mainly a magnetostrictive displacement sensor, which has high measurement accuracy, good reliability and long service life. The disadvantage of the magnetostrictive displacement sensor is that the price is high and the cost performance is not good.

At present, there are also reports on the use of wire-drawing encoders to measure hydraulic cylinder strokes in published materials. Due to the high measurement accuracy and low price of the wire draw encoder, its cost performance is better. However, in the reports, the external installation method is used to fix the wire encoder. Usually, the cable encoder is fixed on the bracket next to the outside of the hydraulic cylinder, and the cable of the encoder is fixed on the exposed part of the piston rod of the hydraulic cylinder. Due to the external installation, the cable of the encoder is exposed in the surrounding environment and is easily damaged. The wire-drawn encoder will cause a decrease in the travel measurement accuracy if it is light, and it will cause equipment and personal safety accidents if it is serious.

Contents of the invention

In view of the above disadvantages, the purpose of the present invention is to provide a built-in stroke measuring hydraulic cylinder, which requires a small installation space, is easy to maintain and has a good cost performance.

The technical content of the present invention is a built-in stroke measuring hydraulic cylinder, which is characterized in that it includes a cable encoder, an encoder bracket, a cylinder bottom, a cylinder barrel, a cable protection tube, a piston, a piston rod, a cylinder head, and a cable fixing pin and screw plugs;

The cylinder bottom is fixed at one end of the cylinder barrel, the cylinder head is set at the other end of the cylinder barrel, and the piston is set inside the cylinder barrel; there is a cable through hole in the piston rod, and the front end of the piston rod extends into the cylinder barrel through the cylinder head and The piston is fixedly connected; the piston divides the inner cavity of the cylinder into a rod cavity and a rodless cavity. There is a rodless oil inlet connected to the rodless cavity on the bottom of the cylinder, and a rodless oil inlet connected to the rod cavity is provided on the cylinder head. One end of the cable protection tube passes through the cylinder bottom and the piston in turn and extends into the cable through hole of the piston rod. The encoder bracket is fixedly installed on the cylinder bottom corresponding to the other end of the cable protection tube. The cable encoder Set on the encoder bracket, the backguy of the backguy encoder stretches into the backguy through hole of the piston rod through the backguy protection tube, and then is stuck on the end face of the piston rod rear end with the backguy fixing pin and is fixedly arranged on the back end of the piston rod by a screw plug.

In order to facilitate the fixing of the cable protection tube, the above-mentioned built-in stroke measuring hydraulic cylinder also includes a key, and the cable protection tube is fixed on the bottom of the cylinder through the key, and the encoder bracket simultaneously presses the key into the counterbore of the cylinder bottom. Prevent the axial movement of the key and the cable protection tube; in order to improve the sealing performance of the hydraulic cylinder, a piston rod sealing ring is provided between the cylinder head and the piston rod, and a cylinder head sealing ring is provided between the cylinder head and the cylinder barrel. There is a piston static sealing ring between the piston and the piston rod, a piston dynamic sealing ring between the piston and the cylinder, a protective tube dynamic sealing ring between the piston and the cable protection tube, and a protective tube sealing ring between the cylinder bottom and the cylinder tube. A cylinder bottom sealing ring is arranged between them, and a protective tube static sealing ring is arranged between the cylinder bottom and the guy wire protective tube.

The piston dynamic sealing ring is used to seal the gap between the cylinder and the piston to prevent hydraulic oil from leaking between the rod cavity and the rodless force. The piston static sealing ring is used to seal the gap between the piston and the piston rod to prevent hydraulic oil from leaking from the gap. The cylinder bottom is fixed on the cylinder barrel with a set of cylinder bottom screws, and the cylinder bottom sealing ring prevents hydraulic oil from leaking from the gap between the cylinder bottom and the cylinder barrel. The cylinder head is also fixed on the cylinder barrel with a set of cylinder head screws, and the cylinder head seal ring prevents hydraulic oil from leaking from the gap between the cylinder head and the cylinder barrel. The piston rod seal is used to prevent hydraulic oil from leaking from the gap between the piston rod and the cylinder head when the piston rod moves. The cable protection tube is fixed at the center of the cylinder bottom with a key, and the static sealing ring of the protection tube prevents hydraulic oil from leaking from the gap between the cylinder bottom and the cable protection tube. The protective tube dynamic sealing ring is used to prevent the hydraulic oil from leaking from the gap between the piston and the cable protective tube when the piston moves. The encoder bracket is fixed on the bottom of the cylinder with a set of bracket screws, and at the same time, the key is pressed into the counterbore of the bottom of the cylinder to prevent the key and the cable protection tube from moving axially. The pull-wire encoder is fixed on the encoder bracket with encoder screws. The stay wire on the stay wire encoder passes through the center of the stay wire protection tube, and then is clamped in the counterbore on the end face of the piston rod with a stay wire fixing pin, and fixed with a screw plug.

Changes in the position of the piston rod assembly of the hydraulic cylinder are detected by a wire-drawn encoder. The pulse signal output by the cable encoder is supplied to the host computer such as digital instrument, programmable controller, computer, etc., and the movement position, movement direction and movement speed of the piston rod of the hydraulic cylinder can be calculated.

The pull wire of the pull wire encoder is built into the hydraulic cylinder, which has the characteristics of simple structure, reliable protection and not easy to be damaged.

The cable protection tube is used to protect the cable of the cable encoder, which can prevent the high pressure oil inside the hydraulic cylinder from damaging the cable of the encoder.

The piston rod has a hollow structure, which is convenient for fixing the cable of the encoder at the end of the piston rod, and also convenient for the maintenance and replacement of the cable encoder.

The key for fixing the cable protection tube has a two-half structure, which is convenient to be installed in the outer circular card groove of the cable protection tube.

Compared with the prior art, the present invention has the following advantages: the present invention uses a wire-guide encoder as a sensor for stroke measurement, which has the characteristics of high measurement accuracy and good cost performance. It is better protected and not easy to be damaged; therefore, the present invention also has the advantages of compact installation space, convenient installation and maintenance, not easy to be damaged, and long service life.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Detailed ways

As shown in Figure 1, a built-in stroke measuring hydraulic cylinder is characterized by its cable encoder 1, encoder bracket 2, card key 3, cylinder bottom 4, cylinder barrel 5, cable protection tube 6, piston 7, piston Rod 8, cylinder head 9, cable fixing pin 10, screw plug 11, cylinder head screw 12, piston rod sealing ring 13, cylinder head sealing ring 14, piston static sealing ring 15, piston dynamic sealing ring 16, protective tube dynamic sealing ring 17. Cylinder bottom sealing ring 18, protective pipe static sealing ring 19, cylinder bottom screw 20, bracket screw 21, encoder screw 22;

The cylinder bottom 4 is fixed on one end of the cylinder barrel 5 with a set of cylinder bottom screws 20, the cylinder head 9 is fixed on the other end of the cylinder barrel 5 with a set of cylinder head screws 12, and the piston 7 is arranged in the cylinder barrel 5; There is a pull wire through hole 8.1 in the middle, and the front end of the piston rod 8 passes through the cylinder cover 9 and extends into the cylinder barrel 5 to be fixedly connected with the piston 7; the piston 7 divides the inner cavity of the cylinder barrel 5 into a rod chamber 5.1 and a rodless chamber 5.2, A rodless oil inlet hole 4.1 connected with the rodless chamber 5.2 is provided on the cylinder bottom 4, and a rodd oil inlet hole 9.1 connected with the rod chamber 5.1 is provided on the cylinder head 9; Fixed at the center of the cylinder bottom 4, one end of the cable protection tube 6 passes through the cylinder bottom 4 and the piston 7 in turn and extends into the cable through hole 8.1 of the piston rod 8. On the cylinder bottom 4 corresponding to the other end of the tube 6, press the key 3 into the counterbore of the cylinder bottom 4 at the same time to prevent the key 3 and the cable protection tube 6 from moving axially.

The pull wire encoder 1 is fixed on the encoder bracket 2 with the encoder screw 22, the pull wire 1.1 of the pull wire encoder 1 extends into the pull wire through hole 8.1 of the piston rod 8 through the pull wire protection tube 6, and then is stuck on the piston with the pull wire fixing pin 10. The end surface of the rear end of the rod 8 is fixedly arranged on the rear end of the piston rod 8 by a screw plug 11 .

A piston rod sealing ring 13 is provided between the cylinder head 9 and the piston rod 8, a cylinder head sealing ring 14 is provided between the cylinder head 9 and the cylinder barrel 5, and a piston static seal is provided between the piston 7 and the piston rod 8. Ring 15, a piston dynamic sealing ring 16 is provided between the piston 7 and the cylinder 5, a protective tube dynamic sealing ring 17 is provided between the piston 7 and the wire protection tube 6, and a dynamic sealing ring 17 is provided between the cylinder bottom 4 and the cylinder 5. A cylinder bottom seal ring 18 is arranged, and a protection pipe static seal ring 19 is provided between the cylinder bottom 4 and the backguy protection pipe 6 .

The working principle of the present invention is that the backguy 1.1 of the backguy encoder 1 passes through the center of the backguy protection tube 6 and the piston rod 8, and is stuck in the counterbore on the end face of the piston rod 8 by the backguy fixing pin 10, and is fixed by a screw plug 11. When the hydraulic cylinder is working, the movement of the piston rod 8 drives the pull wire 1.1 to expand and contract, and the stretch of the pull wire 1.1 drives the pull wire encoder 1 to output pulse signals. The pulse signal is supplied to the host computer such as digital instrument, programmable controller, computer, etc., and the host computer detects the number, polarity and frequency of the pulse, and can calculate the movement position, movement direction and movement speed of the hydraulic cylinder piston rod 8.

The specific working process is: when the piston rod of the hydraulic cylinder is stretched out, the rodless oil inlet hole 4.1 on the cylinder bottom 4 is supplied with hydraulic oil, and the hydraulic oil enters the rodless chamber 5.2 to push the piston 7 and the piston rod 8 assembly to move to the right. The hydraulic oil in cavity 5.1 is discharged through the rod oil inlet hole 9.1 on the cylinder head 9; the movement of the piston rod 8 to the right drives the extension of the cable 1.1, and the cable encoder 1 outputs positive pulses of a certain number and frequency. signal, it can be determined that the piston rod of the hydraulic cylinder is extending, and the extending position and speed of extending can be calculated at the same time; Enter the rod chamber 5.1, push the piston 7 and the piston rod 8 assembly to move to the left, and the hydraulic oil in the rodless chamber 5.2 is discharged through the rodless oil inlet hole 4.1 on the cylinder bottom 4; the movement of the piston rod 8 to the left drives the pull wire 1.1 to shorten, and the pull wire Encoder 1 outputs a certain number and frequency of negative pulses. By comparing the pulse signals, the host computer can determine that the piston rod of the hydraulic cylinder is retracting, and at the same time calculate the retracting position and retracting speed.

Claims (3)

1. a kind of built-in stroke measurment hydraulic cylinder, it is characterized in that it include draw wire encoder, encoder bracket, cylinder bottom, cylinder barrel, Bracing wire pillar, piston, piston rod, cylinder cap, bracing wire fixed pin and plug screw；

Cylinder bottom is fixed at one end of cylinder barrel, and the other end of cylinder barrel is arranged in cylinder cap, and piston is arranged in cylinder barrel；In piston rod In be equipped with a bracing wire through-hole, piston rod front end passes through cylinder cap and protrudes into cylinder barrel and be fixedly connected with the piston；Piston is by cylinder barrel internal cavity Be divided into rod chamber and rodless cavity, be equipped on cylinder bottom one be connected to rodless cavity without bar fuel feed hole, on cylinder cap equipped with one and Rod chamber connection has bar fuel feed hole；Bracing wire pillar one end sequentially passes through cylinder bottom and piston extend into the bracing wire through-hole of piston rod In, encoder bracket is fixedly mounted on cylinder bottom corresponding with the bracing wire pillar other end, and draw wire encoder is arranged in encoder branch On frame, the bracing wire of draw wire encoder with bracing wire fixed pin is stuck in work after extending into the bracing wire through-hole of piston rod by bracing wire pillar The end face of stopper rod rear end is simultaneously fixed at piston rod rear end by plug screw.

2. a kind of built-in stroke measurment hydraulic cylinder according to claim 1, it is characterized in that it further includes card key, bracing wire shield Pipe is fixed on cylinder bottom by card key, and card key is pressed in the counterbore of cylinder bottom by encoder bracket simultaneously, prevents card key and bracing wire Pillar axial float.

3. a kind of built-in stroke measurment hydraulic cylinder according to claim 1, it is characterized in that between cylinder cap and piston rod Equipped with piston rod seals, it is equipped with cylinder cap sealing ring between cylinder cap and cylinder barrel, it is quiet that piston is equipped between piston and piston rod Sealing ring is equipped with piston dynamic seal ring between piston and cylinder barrel, and pillar dynamic seal ring is equipped between piston and bracing wire pillar, It is equipped with cylinder bottom sealing ring between cylinder bottom and cylinder barrel, pillar static sealing ring is equipped between cylinder bottom and bracing wire pillar.