JP6944100B2 - Hydraulic cylinder device and hydraulic cylinder device hydraulic leak detection method - Google Patents

Description

The present invention comprises a hydraulic cylinder, a hydraulic fluid supply / discharge mechanism for supplying / discharging the hydraulic fluid to the hydraulic cylinder, and a hydraulic fluid leakage detection mechanism for detecting a hydraulic fluid leak inside the hydraulic cylinder or in the hydraulic fluid supply / discharge mechanism. The present invention relates to a hydraulic cylinder device including the above and a method for detecting a hydraulic leak in the hydraulic cylinder device.

In general, a hydraulic cylinder in which a piston fitted in a cylinder is driven by the pressure of a hydraulic fluid discharged from a pump to reciprocate is a mechanical actuator that reciprocates in the same manner, for example, a rack pinion mechanism or a ball. Compared to screw mechanisms and the like, it has the advantages of a simple structure, high output, and long life, so it is widely used as an actuator for various mechanical devices and civil engineering and construction vehicles. As such a hydraulic cylinder, a single-rod type double-acting hydraulic cylinder that uses hydraulic oil as a hydraulic fluid has become widespread (see, for example, Patent Documents 1 to 3).

The single-rod type double-acting hydraulic cylinder is provided with a hydraulic oil supply / discharge mechanism for supplying / discharging the hydraulic oil discharged from the hydraulic pump to the hydraulic cylinder. The hydraulic oil supply / discharge mechanism includes a hydraulic oil storage tank, a hydraulic oil passage having a plurality of oil passages arranged between the hydraulic oil storage tank and the hydraulic cylinder, and a hydraulic pressure interposed in the hydraulic oil passage. Various hydraulic devices such as pumps, direction switching valves, and flow control valves are provided.

In such a hydraulic oil supply / discharge mechanism, hydraulic oil leakage may occur at the connection portion between the oil passage and the oil passage or the connection portion between the oil passage and the hydraulic equipment. Therefore, various hydraulic cylinder devices including a hydraulic oil leak detection mechanism for detecting a hydraulic oil leak of the hydraulic oil supply / discharge mechanism have been proposed (see, for example, Patent Documents 4 and 5). Specifically, for example, a position detection sensor for detecting the position of the piston rod of the hydraulic cylinder is provided, and when the piston is in the stopped state, the position or displacement of the piston rod is detected to operate the hydraulic oil supply / discharge mechanism. A hydraulic cylinder device capable of detecting an oil leak has been proposed (see, for example, Patent Document 4).

In addition, a level sensor is provided to detect the hydraulic oil level in the hydraulic oil storage tank, and if the hydraulic oil level drops below a preset reference value, a hydraulic oil leak will occur in the hydraulic oil supply / discharge mechanism. A hydraulic cylinder device that determines that the oil cylinder device is used has also been proposed (see, for example, Patent Document 5). In such a hydraulic cylinder device, the liquid level of the hydraulic oil in the hydraulic oil storage tank fluctuates as the operating state of the hydraulic cylinder changes. Therefore, the reference value is usually the lowest in the fluctuation range of the liquid level. It is set to a position slightly below the position.

Japanese Unexamined Patent Publication No. 10-11710 Japanese Unexamined Patent Publication No. 2003-74518 Japanese Unexamined Patent Publication No. 2004-68863 Japanese Unexamined Patent Publication No. 2015-68494 Japanese Unexamined Patent Publication No. 11-241973

However, in a hydraulic cylinder device that detects hydraulic oil leakage of the hydraulic oil supply / discharge mechanism based on the position or displacement of the piston rod, the presence or absence of hydraulic oil leakage or hydraulic oil is not present unless the piston is in the stopped state. Since the amount of leakage cannot be detected, there is a problem that it is difficult to detect hydraulic oil leakage quickly and early.

On the other hand, when the liquid level of the hydraulic oil in the hydraulic oil storage tank drops to a position slightly lower than the lowest position of the fluctuation range, it is determined that the hydraulic oil leakage has occurred in the hydraulic oil supply / discharge mechanism. If a hydraulic oil leak occurs when the hydraulic oil level in the hydraulic oil storage tank is higher than the lowest position in the fluctuation range, the hydraulic oil level drops below the lowest position and the hydraulic oil. There is a problem that the hydraulic oil continues to leak until a leak is detected, and a large amount of hydraulic oil may leak.

Further, in a hydraulic cylinder, a piston packing is generally mounted on the outer peripheral surface of the piston in order to reliably shut off the upper oil chamber and the lower oil chamber. However, when the piston packing is deteriorated or damaged, the upper oil chamber is used. A hydraulic oil leak occurs between the and the lower oil chamber. However, for example, in the conventional hydraulic cylinder device disclosed in Patent Documents 4 and 5, there is a problem that it is difficult to detect such a hydraulic oil leak between the upper oil chamber and the lower oil chamber. ..

The above-mentioned problems are similarly solved not only in a hydraulic cylinder device that uses hydraulic oil as a hydraulic fluid, but also in a hydraulic cylinder device that uses a hydraulic fluid other than hydraulic oil (for example, a hydraulic cylinder device that uses water as the hydraulic fluid). Of course it happens.

The present invention has been made to solve the above-mentioned conventional problems, and the hydraulic fluid leaks in the hydraulic fluid supply / discharge mechanism of the hydraulic cylinder device when the hydraulic cylinder or piston is operating or stopped. The first task is to provide a means capable of detecting the occurrence of the above quickly and at an early stage. A second object is to provide a means for detecting a hydraulic oil leak between the upper oil chamber and the lower oil chamber. It should be noted that both the first problem and the second problem are common in that they both provide a means for quickly and earlyly detecting a hydraulic fluid leak in the hydraulic cylinder device.

The hydraulic cylinder device according to the first aspect of the present invention, which has been made to solve the first problem, includes a hydraulic cylinder driven by a hydraulic fluid (for example, hydraulic oil), and a hydraulic fluid supply / discharge mechanism. , Equipped with a hydraulic leak detecting means. The hydraulic cylinder is coupled to the cylinder, the piston that is fitted into the hollow part of the cylinder and reciprocates in the direction in which the central axis of the cylinder extends, and the lower end of the piston, passes through the hole in the lower wall of the cylinder, and extends from the hollow part of the cylinder to the outside of the cylinder. It has a piston rod, an upper liquid chamber formed of a cylinder hollow portion above the piston, and a lower liquid chamber formed of a cylinder hollow portion below the piston. The hydraulic fluid supply / discharge mechanism is provided in the hydraulic fluid storage tank, the hydraulic fluid passage arranged between the hydraulic fluid storage tank and the hydraulic cylinder, and the hydraulic fluid storage tank via the hydraulic fluid passage. It has a pump that supplies the hydraulic fluid to the hydraulic cylinder, and a direction switching valve that is provided in the hydraulic passage on the hydraulic cylinder side of the pump and switches the supply / discharge path of the hydraulic fluid in the hydraulic passage. The hydraulic fluid leak detecting means detects a hydraulic fluid leak in the hydraulic fluid supply / discharge mechanism.

In this hydraulic cylinder device, the hydraulic liquid leakage detecting means includes a piston position detector, a hydraulic fluid amount detector, a hydraulic fluid amount estimator, and a hydraulic fluid leak determining device. The piston position detector detects the position in the cylinder in the extending direction of the cylinder center axis of the piston. The hydraulic fluid amount detector detects the hydraulic fluid volume (volume) in the hydraulic fluid storage tank. The hydraulic fluid volume estimator has the volume of the upper liquid chamber and the lower liquid chamber corresponding to the piston position detected by the piston position detector, the volume of the hydraulic fluid storage part of the hydraulic fluid supply / discharge mechanism, and the liquid before operation. The estimated value (volume) of the hydraulic fluid in the hydraulic fluid storage tank is calculated based on the volume (volume) of the hydraulic fluid loaded in the pressure cylinder device. In the hydraulic fluid leakage detector, the difference between the hydraulic fluid amount estimated value (predicted value) calculated by the hydraulic fluid volume estimator and the hydraulic fluid volume (measured value) detected by the hydraulic fluid volume detector is set in advance. If it is equal to or higher than the specified threshold value (reference value), it is determined that the hydraulic fluid has leaked to the hydraulic fluid supply / discharge mechanism.

In this hydraulic cylinder device, the hydraulic fluid volume estimator has the volume of the upper liquid chamber and the lower liquid chamber corresponding to the piston position detected by the piston position detector, and the volume of the hydraulic fluid accommodating portion of the hydraulic fluid passage. Based on the volume of the hydraulic fluid accommodating part of the pump, the volume of the hydraulic fluid accommodating portion of the direction switching valve, and the amount of the hydraulic fluid loaded in the hydraulic cylinder device before operation, the hydraulic fluid in the hydraulic fluid storage tank. It is preferable to calculate the quantity estimate. Further, the hydraulic fluid amount detector preferably calculates the hydraulic fluid amount in the hydraulic fluid storage tank based on the liquid level of the hydraulic fluid in the hydraulic fluid storage tank and the area of the cross section of the hydraulic fluid storage tank.

The hydraulic cylinder device according to the second aspect of the present invention, which has been made to solve the second problem, includes a hydraulic cylinder driven by a hydraulic fluid (for example, hydraulic oil), and a hydraulic fluid supply / discharge mechanism. , Equipped with a hydraulic leak detecting means. Here, the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism are substantially the same as the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism of the hydraulic cylinder device according to the first aspect of the present invention, respectively. However, the hydraulic leak detecting means detects not the hydraulic leak of the hydraulic fluid supply / discharge mechanism but the hydraulic leak between the upper liquid chamber and the lower liquid chamber.

The hydraulic fluid leak detecting means includes a piston position detector, a hydraulic fluid flow rate detector, a liquid chamber volume change rate calculator, and a hydraulic fluid leak determining device. The piston position detector detects the position in the cylinder in the extending direction of the cylinder center axis of the piston. The hydraulic fluid flow rate detector is attached to the hydraulic fluid passage, and the flow rate of the hydraulic fluid flowing in or out of the upper liquid chamber (volumetric flow rate) or the flow rate of the hydraulic fluid flowing in or out of the lower liquid chamber (volumetric flow rate). Volumetric flow rate) is detected. The liquid chamber volume change rate calculator calculates the rate of change (liquid chamber volume change rate) with time of the volume of the upper liquid chamber or the lower liquid chamber corresponding to the position of the piston detected by the piston position detector. In the hydraulic fluid leakage detector, the difference between the flow rate of the hydraulic fluid related to the upper liquid chamber or the lower liquid chamber detected by the flow rate detector and the liquid chamber volume change rate calculated by the volume change rate calculator is determined in advance. If it is equal to or higher than the set threshold value (reference value), it is determined that the hydraulic fluid leaks between the upper liquid chamber and the lower liquid chamber.

In this hydraulic cylinder device, the hydraulic fluid passage includes a first passage connecting the first output port (A port) of the direction switching valve and the upper liquid chamber, and a second output port (B port) of the direction switching valve. The second passage that connects the lower liquid chamber, the third passage that connects the pump side port (P port) of the direction switching valve and the hydraulic fluid storage tank, and the pump is provided, and the tank side port of the direction switching valve. It is preferable to have a fourth passage connecting the (T port) and the hydraulic fluid storage tank. In this case, the hydraulic fluid flow rate detector is preferably attached to the first passage or the second passage in the vicinity of the hydraulic cylinder.

The hydraulic cylinder device in the hydraulic liquid leakage detecting method according to the third aspect of the present invention, which is made to solve the first problem, includes a hydraulic cylinder driven by a hydraulic fluid (for example, hydraulic oil) and a hydraulic cylinder. It is equipped with a hydraulic fluid supply / discharge mechanism. Here, the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism are substantially the same as the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism of the hydraulic cylinder device according to the first aspect of the present invention, respectively.

Then, in the method for detecting a hydraulic fluid leak of this hydraulic cylinder device, the hydraulic fluid leak is detected by the following procedure.
(1) The position in the cylinder in the extending direction of the cylinder central axis of the piston is detected.
(2) Detect the amount of hydraulic fluid in the hydraulic fluid storage tank.
(3) Based on the volumes of the upper liquid chamber and the lower liquid chamber corresponding to the piston position, the volume of the hydraulic fluid accommodating portion of the hydraulic fluid supply / discharge mechanism, and the amount of the hydraulic fluid introduced into the hydraulic cylinder device. , Calculate the amount of hydraulic fluid in the hydraulic fluid storage tank.
(4) If the difference between the calculated hydraulic fluid amount estimated value (predicted value) and the detected hydraulic fluid volume (actual measurement value) is equal to or greater than the preset threshold value (reference value), the hydraulic fluid supply / discharge mechanism is connected to the hydraulic fluid. It is determined that there is a leak.

In this hydraulic leak detection method, the volumes of the upper liquid chamber and the lower liquid chamber corresponding to the piston position detected by the piston position detector, the volume of the hydraulic fluid accommodating portion of the hydraulic fluid passage, and the hydraulic fluid of the pump Based on the volume of the accommodating part, the volume of the hydraulic fluid accommodating part of the direction switching valve, and the amount of the hydraulic fluid introduced into the hydraulic cylinder device, the estimated value of the hydraulic fluid in the hydraulic fluid storage tank is calculated. preferable. Further, it is preferable to measure the liquid level of the hydraulic fluid in the hydraulic fluid storage tank and calculate the hydraulic fluid amount in the hydraulic fluid storage tank based on this liquid level and the area of the cross section of the hydraulic fluid storage tank.

The hydraulic cylinder device in the hydraulic liquid leakage detecting method according to the fourth aspect of the present invention, which is made to solve the second problem, includes a hydraulic cylinder driven by a hydraulic fluid (for example, hydraulic oil) and a hydraulic cylinder. It is equipped with a hydraulic fluid supply / discharge mechanism. Here, the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism are substantially the same as the hydraulic cylinder and the hydraulic fluid supply / discharge mechanism of the hydraulic cylinder device according to the first aspect of the present invention, respectively.

Then, in the method for detecting a hydraulic fluid leak of this hydraulic cylinder device, the hydraulic fluid leak is detected by the following procedure.
(1) The position in the cylinder in the extending direction of the cylinder central axis of the piston is detected.
(2) The flow rate of the working liquid flowing in or out of the upper liquid chamber or the flow rate of the working liquid flowing in or out of the lower liquid chamber is detected.
(3) The rate of change of the volume of the upper liquid chamber or the lower liquid chamber corresponding to the piston position with time (liquid chamber volume change rate) is calculated.
(4) If the difference between the flow rate of the hydraulic fluid related to the upper liquid chamber or the lower liquid chamber and the liquid chamber volume change rate is equal to or more than a preset threshold value (reference value), the upper liquid chamber and the lower liquid chamber It is determined that the hydraulic fluid is leaking from the chamber.

According to the hydraulic cylinder device according to the first aspect of the present invention or the hydraulic liquid leakage detection method according to the third aspect of the present invention, the hydraulic pressure is generated both when the hydraulic cylinder or piston is operating and when the piston is stopped. Occurrence of hydraulic fluid leakage in the hydraulic fluid supply / discharge mechanism of the cylinder device can be detected quickly and early. Further, according to the hydraulic leak detection method of the hydraulic cylinder device according to the second aspect of the present invention or the hydraulic cylinder device according to the fourth aspect of the present invention, the upper liquid is operated when the hydraulic cylinder or the piston is operated. It is possible to detect hydraulic fluid leakage between the chamber and the lower liquid chamber quickly and early.

It is a hydraulic circuit diagram of the hydraulic cylinder apparatus which includes the hydraulic cylinder, the hydraulic oil supply / discharge mechanism, and the hydraulic oil leakage detection means. It is a partial cross-sectional elevation view of the hydraulic cylinder shown in FIG. It is an elevation sectional view of the bubble removal mechanism provided in the piston of the hydraulic cylinder shown in FIG. It is a simplified view of the hydraulic circuit diagram shown in FIG. 1, and shows the volume or liquid level of hydraulic oil in the main part of the cylinder device. (A) is a graph showing the change characteristics of the piston position with time, (b) is a graph showing the change characteristics of the volume of the upper oil chamber and the volume of the lower oil chamber with time, and (c) is a graph showing the hydraulic pressure. It is a graph which shows the change characteristic of the hydraulic oil amount in a cylinder with time, (d) is a graph which shows the change characteristic of the hydraulic oil amount in a hydraulic oil storage tank with time, and (e) is the hydraulic oil in a hydraulic cylinder. It is a graph which shows the change characteristic with respect to the piston position of the amount and the amount of hydraulic oil in a hydraulic oil storage tank.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. In this embodiment, a hydraulic cylinder device, which is a typical hydraulic cylinder device, will be described, but the present invention is a hydraulic cylinder device using a hydraulic fluid other than hydraulic oil (for example, water, processing water, etc.). Of course, the same can be applied to (for example, a hydraulic cylinder device).

As shown in FIG. 1, the hydraulic cylinder device S according to the embodiment of the present invention includes a single-rod type double-acting hydraulic cylinder 1. The hydraulic cylinder 1 includes a substantially cylindrical cylinder 2, a substantially cylindrical piston 3 fitted in a hollow portion of the cylindrical cylinder, and an elongated cylindrical piston rod 4 attached to the lower side of the piston 3. ing. The hydraulic cylinder 1 is a vertical hydraulic cylinder arranged so that the central axes of the cylinder 2, the piston 3, and the piston rod 4 face each other in the vertical direction (vertical direction). The lower end of the piston rod 4 is connected to a load 5 (for example, a door body of a floodgate) that is moved in the vertical direction by the hydraulic cylinder 1.

The piston 3 can slide or slide in the vertical direction in the hollow portion of the cylinder, and the hollow portion of the cylinder is partitioned up and down by the piston 3, and the upper oil chamber 6 is formed on the upper side of the piston 3, while the piston 3 A lower oil chamber 7 is formed on the lower side. Then, in the hydraulic cylinder 1, when the pressurized hydraulic oil is supplied to the upper oil chamber 6, the piston 3 and the piston rod 4 are moved downward by the pressure of the hydraulic oil, and the pressurized hydraulic oil is released. When supplied to the lower oil chamber 7, the pressure of the hydraulic oil causes the piston 3 and the piston rod 4 to move upward, which causes the load 5 to move downward or upward. The piston 3 is provided with a bubble discharge mechanism (see FIG. 3) for discharging bubbles in the hydraulic oil in the cylinder 2 to the outside of the cylinder, as will be described in detail later.

Further, the hydraulic cylinder device S supplies the hydraulic oil pressurized to the hydraulic cylinder 1 to one of the upper oil chamber 6 and the lower oil chamber 7, and the other oil chamber. A hydraulic oil supply / discharge mechanism 10 is provided to discharge the hydraulic oil from the oil chamber. The hydraulic oil supply / discharge mechanism 10 is provided with an electromagnetic directional control valve 11 which is a 4-port 3-position directional control valve. A port P1 (first output port) and B port P2 (second output port) of the direction switching valve 11 pass through the first oil passage 12 and the second oil passage 13, respectively, to the upper oil chamber 6 and the lower side. It is connected to the oil chamber 7. Further, the third oil passage 14 and the fourth oil passage 15 are connected to the P port P3 (pump side port) and the T port P4 (hydraulic oil storage tank side port) of the direction switching valve 11, respectively, and the third oil passage is connected. The tips of the 14 and the fourth oil passage 15 (the end not connected to the direction switching valve 11) are introduced (immersed) in the hydraulic oil storage tank 16 for storing the hydraulic oil.

An oil filter 17 for removing foreign matter in the hydraulic oil sucked into the third oil passage 14 is attached to the tip of the third oil passage 14, and the oil filter 17 is always stored in the hydraulic oil storage tank 16. It is immersed in the hydraulic oil. Further, a hydraulic pump 19 driven by an electric motor 18 (or a prime mover such as gasoline esidine) is interposed in the third oil passage 14. The hydraulic pump 19 sucks the hydraulic oil in the hydraulic oil storage tank 16 and pressurizes it to supply it to the P port P3 of the direction switching valve 11. Regarding the flow direction of the hydraulic oil, a first bypass oil passage 20 for connecting the third oil passage 14 and the fourth oil passage 15 on the downstream side (direction switching valve side) of the hydraulic pump 19 is provided. A relief valve 21 for adjusting the pressure of the hydraulic oil discharged from the hydraulic pump 19 is provided in the first bypass oil passage 20.

The direction switching valve 11 switches the supply / discharge path of hydraulic oil between the direction switching valve 11 and the hydraulic cylinder 1. Although not shown in detail, the direction switching valve 11 is a solenoid valve controlled by a control device (not shown), and the hydraulic oil pressurized by the hydraulic pump 19 and supplied to the P port P3 is the first oil. The first state in which the oil is supplied to the upper oil chamber 6 via the passage 12, the second state in which the oil is supplied to the lower oil chamber 7 via the second oil passage 13, and the hydraulic cylinder 1 is not supplied with hydraulic oil. It can be set to any of the third states.

When the direction switching valve 11 is in the first state, the hydraulic oil in the lower oil chamber 7 returns to the hydraulic oil storage tank 16 via the second oil passage 13 and the fourth oil passage 15. When the direction switching valve 11 is in the second state, the hydraulic oil in the upper oil chamber 6 returns to the hydraulic oil storage tank 16 via the first oil passage 12 and the fourth oil passage 15. When the direction switching valve 11 is in the third state, the ends of the first oil passage 12 and the second oil passage 13 on the direction switching valve side are closed while containing the hydraulic oil.

In the first oil passage 12, a first pilot-operated check valve that basically blocks the flow of hydraulic oil from the hydraulic cylinder side to the direction switching valve side in order from the direction switching valve side to the hydraulic cylinder side. A flow rate adjusting valve 26 with a first check valve, which is composed of a flow rate adjusting valve 26a and a check valve 26b connected in parallel with each other, is interposed in series with the 25. The flow rate adjusting valve 26 with a first check valve does not particularly regulate the flow of hydraulic oil from the direction switching valve side to the hydraulic cylinder side, but adjusts the flow rate of hydraulic oil from the hydraulic cylinder side to the direction switching valve side. .. When a hydraulic pressure (pilot pressure) equal to or higher than the set pressure is applied to the second oil passage 13, the first pilot-operated check valve 25 is opened, and the direction switching valve side is opened from the hydraulic cylinder side in the first oil passage 12. Allows the flow of hydraulic oil to.

On the other hand, in the second oil passage 13, a second pilot-operated reverse type that basically blocks the flow of hydraulic oil from the hydraulic cylinder side to the direction switching valve side in order from the direction switching valve side to the hydraulic cylinder side. A stop valve 27 and a flow control valve 28 with a second check valve composed of a flow control valve 28a and a check valve 28b connected in parallel to each other are interposed in series. The flow rate adjusting valve 28 with a second check valve does not particularly regulate the flow of hydraulic oil from the direction switching valve side to the hydraulic cylinder side, but adjusts the flow rate of hydraulic oil from the hydraulic cylinder side to the direction switching valve side. .. When a hydraulic pressure (pilot pressure) equal to or higher than the set pressure is applied to the first oil passage 12, the second pilot-operated check valve 27 is opened, and the direction switching valve side is opened from the hydraulic cylinder side in the second oil passage 13. Allows the flow of hydraulic oil to.

The first on-off valve 30 is provided in the first oil passage 12 on the hydraulic cylinder side of the flow rate adjusting valve 26 with the first check valve, while the second on-off valve 30 is provided on the hydraulic cylinder side of the flow rate adjusting valve 28 with the second check valve. A second on-off valve 31 is provided in the oil passage 13. Then, at a position on the direction switching valve side from the first and second on-off valves 30 and 31 and on the hydraulic cylinder side from the first and second check valve flow rate adjusting valves 26 and 28, the first oil passage 12 and A second bypass oil passage 32 connecting to the second oil passage 13 is provided, and a third on-off valve 33 is interposed in the second bypass oil passage 32.

The hydraulic cylinder device S detects a hydraulic oil leak in the hydraulic oil supply / discharge mechanism 10 (hereinafter referred to as “supply / discharge mechanism hydraulic oil leak”), and the cylinder 2 between the upper oil chamber 6 and the lower oil chamber 7 A hydraulic oil leak detecting means 34 for detecting a hydraulic oil leak (hereinafter referred to as "cylinder internal hydraulic oil leak") via a sliding contact portion of the piston 3 is provided. Then, the hydraulic oil leak detecting means 34 includes a piston position sensor 35 (piston position detector) that detects the position of the piston 3 in the vertical direction (the direction in which the cylinder central axis extends) in the hollow portion of the cylinder, and the hydraulic oil storage tank 16. A level sensor 36 that detects the position or height of the oil level of the hydraulic oil, and a first flow sensor 37 that detects the flow rate of the hydraulic oil that flows in and out of the upper oil chamber 6 via the first oil passage 12. (Flow detector) and a second flow sensor 38 (flow detector) that detects the flow rate of hydraulic oil flowing in and out of the lower oil chamber 7 via the second oil passage 13. ..

Further, the hydraulic oil leak detecting means 34 has a computer, the position of the piston 3 detected by the piston position sensor 35, the position of the oil level in the hydraulic oil storage tank 16 detected by the level sensor 36, and the first. Based on the flow rate of hydraulic oil detected by the second flow rate sensors 37 and 38 and the specifications or specifications of the hydraulic cylinder 1 and the hydraulic oil supply / discharge mechanism 10, the hydraulic oil leak of the supply / discharge mechanism and the hydraulic oil leak inside the cylinder. It is equipped with a calculation device 39 (hydraulic fluid amount estimator, hydraulic fluid leakage determination device) that detects the presence or absence of hydraulic oil or the amount of hydraulic oil leak. The specific configuration and function of the hydraulic oil leak detecting means 34 will be described in detail later.

As shown in FIG. 2, the cylinder 2 has a cylindrical member 40 forming its main body, a substantially cylindrical upper end plate 41 that closes an opening end on the upper side (cap side) of the cylindrical member 40, and a lower portion of the cylindrical member 40. It is provided with a substantially cylindrical lower end plate 42 that closes the open end on the side (rod side). In the following, in order to simply show the positional relationship of each component of the hydraulic cylinder 1, the direction perpendicular to the vertical direction (the direction in which the central axis of the cylinder 2, the piston 3 or the piston rod 4 extends) is appropriately referred to as the "lateral direction". I will say that.

The inside of the upper end plate 41 is composed of a horizontal hole 43a extending linearly in the lateral direction (diameter direction of the upper end plate 41) and a plurality of vertical holes 43b extending downward from the horizontal hole 43a and opening into the upper oil chamber 6. An oil passage 43 in the upper end plate is formed. Here, one end of the lateral hole 43a is connected to the first oil passage 12, and the other end is closed. The lower oil chamber 7 is connected to the second oil passage 13 via a hole 45 formed near the lower end of the cylindrical member 40.

Slightly above the lower end of the piston 3, it bulges laterally to the outer periphery of the piston due to the hydraulic pressure in the lower oil chamber 7 when the piston 3 moves upward, and seals the gap between the piston 3 and the cylindrical member 40 (seal). ) The first piston packing 46 is attached. The first piston packing 46 is made of a flexible or elastic material (for example, nitrile rubber, polyurethane rubber, fluororubber, etc.) and has a ring shape having a substantially U-shaped or substantially V-shaped vertical cross section. Lip packing. The first piston packing 46 has a lip portion located on the lower side (facing downward) and a heel portion in the first annular groove 47 formed on the outer peripheral portion of the piston so as to make a circumference of the piston 3 in the circumferential direction. It is housed (fitted) in a posture that is located on the upper side. Here, when the first piston packing 46 is deteriorated or damaged, the lower oil chamber 7 to the upper oil chamber when the pressurized hydraulic oil is supplied to the lower oil chamber 7 and the piston 3 rises. A hydraulic oil leak to No. 6 (a hydraulic oil leak inside the cylinder) occurs.

A second piston that bulges laterally to the outer periphery of the piston slightly below the upper end of the piston 3 due to the hydraulic pressure in the upper oil chamber 6 when the piston 3 moves downward to seal the cylinder-piston gap. The packing 48 is attached. The second piston packing 48 is a ring-shaped lip packing which is made of a flexible or elastic material and has a substantially U-shaped or substantially V-shaped vertical cross section, similar to the first piston packing 46. In the second piston packing 48, the lip portion is located on the upper side and the heel portion is located on the lower side in the second annular groove 49 formed on the outer peripheral portion of the piston so that the piston 3 goes around in the circumferential direction. It is housed (fitted) in a proper posture. Here, when the second piston packing 48 is deteriorated or damaged, when the pressurized hydraulic oil is supplied to the upper oil chamber 6 and the piston 3 is lowered, the upper oil chamber 6 is moved to the lower oil chamber 7. Hydraulic oil leak (leakage of hydraulic oil inside the cylinder) occurs.

A substantially cylindrical support member 51 that slidably supports the piston rod 4 in the vertical direction is attached to the lower end wall 42 of the cylinder 2. Then, the piston rod 4 passes through the rod insertion hole 52 formed in the central portion of the support member 51 and projects downward. The gap between the piston rod 4 and the rod insertion hole 52 is sealed by the first rod packing 53 and the second rod packing 54.

When the piston 3 rises to the uppermost position or the vicinity of the uppermost position in the reciprocating stroke, the hydraulic cylinder 1 is in hydraulic oil in the vicinity of the first piston packing 46 or the first annular groove 47 or the lower end surface of the piston 3. A bubble discharge mechanism is provided to discharge the air bubbles staying in the cylinder to the outside of the cylinder. Hereinafter, the configuration and function of this bubble discharge mechanism will be described.

As shown in FIG. 3, a vertical hydraulic oil passage 60 having an upper end opening on the upper end surface of the piston and extending linearly in the vertical direction is formed in the central portion of the piston 3 or in the vicinity of the central axis. Further, one end of each of the pistons 3 is connected to the lower end of the vertical hydraulic oil passage 60, extends radially in the piston radial direction (horizontal direction), and the other end opens at the annular bottom of the first annular groove 47. A plurality of (for example, 2 to 8) horizontal hydraulic oil passages 61 are formed.

Then, in the vicinity of the lower end portion of the vertical hydraulic oil passage 60, when the piston 3 is lowered by the oil pressure of the upper oil chamber 6, the upper oil chamber 6 passes through the vertical hydraulic oil passage 60 and the horizontal hydraulic oil passage 61. A first check valve 62 is provided to prevent the hydraulic oil from flowing from the lower oil chamber 7 to the lower oil chamber 7. The first check valve 62 is arranged above the valve seat 63 in the vertical hydraulic oil passage 60 and the valve seat 63 arranged in the vertical hydraulic oil passage 60, and moves in the vertical direction to open and close the valve seat 63. It has a valve body 64 and a coil spring 65 that urges the valve body 64 downward, that is, in a direction in which the valve body 64 closes the valve seat 63.

On the other hand, in the vicinity of the upper end of the vertical hydraulic oil passage 60, when the piston 3 is raised by the oil pressure of the lower oil chamber 7, the lower oil passes through the horizontal hydraulic oil passage 61 and the vertical hydraulic oil passage 60. A second check valve 66 is provided to prevent the hydraulic oil from flowing from the chamber 7 to the upper oil chamber 6. The second check valve 66 is arranged below the valve seat 67 arranged in the vertical hydraulic oil passage 60 and the valve seat 67 in the vertical hydraulic oil passage 60 and moves in the vertical direction to open and close the valve seat 67. It has a valve body 68 and a coil spring 69 that urges the valve body 68 upward, that is, in a direction in which the valve body 68 closes the valve seat 67. The valve seat 67 is provided with a slight gap (for example, 5 to 15 mm) from the upper end opening of the vertical hydraulic oil passage 60 (hereinafter referred to as “hydraulic oil passage opening”) to form the hydraulic oil passage opening. It is located below.

Then, on the upper side of the valve body 68 of the second check valve 66, when the piston 3 rises to the uppermost position or the vicinity of the uppermost position of the reciprocating movement stroke, the valve body 68 is moved downward to stop the second check valve. A rod-shaped member 71 (valve opening member) for forcibly opening the valve 66 is provided.

Thus, when the lower oil chamber 7 is supplied with pressurized hydraulic oil and the piston 3 is raised, and the piston 3 has not reached the uppermost position or its vicinity thereof, the rod-shaped member 71 is subjected to the rod-shaped member 71. Since no downward force is applied to the valve body 68 other than the force due to its own weight, the valve body 68 closes the valve seat 67 by the hydraulic pressure on the lower oil chamber side and the urging force of the coil spring 69. At this time, the rod-shaped member 71 projects upward as much as possible from the hydraulic oil passage opening. In this state, the second check valve 66 exerts a normal function as a check valve and prevents hydraulic oil from flowing from the lower oil chamber side to the upper oil chamber side.

Then, when the piston 3 reaches its uppermost position or its vicinity, the rod-shaped member 71 abuts on the upper end wall 41 of the cylinder 2 and presses it upward, but the upper end wall 41 does not displace, so that reaction force or its reaction force or The rod-shaped member 71 moves downward due to the reaction. As a result, the rod-shaped member 71 moves the valve body 68 downward against the oil pressure on the lower oil chamber side and the urging force of the coil spring 69. In this state, the second check valve 66 loses its normal function as a check valve, and the hydraulic oil can flow from the lower oil chamber side to the upper oil chamber side.

When the pressurized hydraulic oil is supplied to the lower oil chamber 7 and the piston 3 rises and reaches the uppermost position or its vicinity thereof, the pressurized hydraulic oil in the lower oil chamber 7 is released. , The cylinder-piston gap near the lower end of the piston, the first annular groove 47, the plurality of horizontal hydraulic oil passages 61, and the vertical hydraulic oil passage 60 flow at high speed and flow into the upper oil chamber 6. At that time, air bubbles existing in the cylinder-piston gap near the first piston packing 46 or the first annular groove 47, or air bubbles existing near the lower end portion of the piston 3 accompany the hydraulic oil to the upper oil chamber 6. Inflow. After that, the air bubbles in the upper oil chamber 6 are discharged to the first oil passage 12 together with the hydraulic oil via the oil passage 43 having no upper end wall. Therefore, in the upper oil chamber 6 and the lower oil chamber 7, air bubbles do not stay in the hydraulic oil. That is, the volume of the upper oil chamber 6 and the volume of the hydraulic oil in the upper oil chamber 6 are the same, and the volume of the lower oil chamber 7 and the volume of the hydraulic oil in the lower oil chamber 7 are the same. As a result, the accuracy of detecting the hydraulic oil leak of the hydraulic oil leak detecting means 34 is greatly improved.

Hereinafter, with reference to FIGS. 1, 4 and 5 (a) to 5 (e), the specific configuration and function of the hydraulic oil leak detecting means 34 and the hydraulic oil leak detecting method of the hydraulic oil leak detecting means 34 will be described. explain. As described above, the hydraulic oil leak detecting means 34 includes a piston position sensor 35 that detects the vertical position of the piston 3 and a level sensor that detects the position (liquid level) of the hydraulic oil level in the hydraulic oil storage tank 16. It has 36, first and second flow rate sensors 37 and 38 for detecting the flow rate of hydraulic oil in the first and second oil passages 12 and 13, and a computing device 39 equipped with a computer.

The piston position sensor 35 detects the vertical position of the piston 3 by detecting the vertical position of the piston rod 4. That is, since the relative position or distance between the piston 3 and the piston rod 4 in the vertical direction is constant, the position of the piston rod 4 is detected and the position of the piston 3 is calculated based on this. In this embodiment, the position of the upper end surface of the piston 3 is detected or calculated. As the piston position sensor 35, for example, a magnetostrictive sensor, a linear encoder, or the like can be used. In the present invention, the type of the piston position sensor 35 is not particularly limited, and any type may be used as long as the position of the piston rod 4 and thus the piston 3 in the vertical direction can be automatically detected. .. The piston position sensor 35 can calculate the rate of change of the vertical position of the piston 3 with respect to time, that is, the moving speed of the piston 3. It should be noted that this calculation may be performed by the arithmetic unit 39.

The level sensor 36 is a laser type or ultrasonic type level sensor arranged above the hydraulic oil storage tank 16, emits laser light or ultrasonic waves on the oil surface of the hydraulic oil, and is in a state of reflected waves (phase, etc.). ), The position (liquid level) of the oil level of the hydraulic oil is detected by measuring the distance between the level sensor 36 and the oil level. In the present invention, the type of the level sensor 36 is not particularly limited, and any type may be used as long as the position of the oil level of the hydraulic oil can be automatically detected. The level sensor 36 can calculate the amount (volume) of the hydraulic oil in the hydraulic oil storage tank 36 based on the position of the oil level of the hydraulic oil and the area of the cross section of the hydraulic oil storage tank 16. It should be noted that this calculation may be performed by the arithmetic unit 39.

The first flow rate sensor 37 is attached to or interposed in the first oil passage 12 in the vicinity of the hydraulic cylinder 1, and the flow rate of hydraulic oil flowing into the upper oil chamber 6 via the first oil passage 12 or the upper oil chamber. The flow rate of the hydraulic oil flowing out from No. 6 to the first oil passage 12 is automatically detected. The first flow rate sensor 37 may detect only the flow rate of the hydraulic oil flowing into the upper oil chamber 6 via the first oil passage 12. The second flow rate sensor 38 is attached to or interposed in the second oil passage 13 in the vicinity of the hydraulic cylinder 1, and the flow rate of the hydraulic oil flowing into the lower oil chamber 7 via the second oil passage 13 or the lower side. The flow rate of the hydraulic oil flowing out from the oil chamber 7 to the second oil passage 13 is automatically detected. The second flow rate sensor 38 may detect only the flow rate of the hydraulic oil flowing into the lower oil chamber 7 via the second oil passage 13.

The computing device 39 is a comprehensive computing device equipped with a computer, including a hydraulic fluid volume estimator, a hydraulic fluid leak determining device, etc. described in the [Means for Solving Problems] column of the present specification. The computing device 39 is provided with the position or moving speed of the upper end surface of the piston 3 detected by the piston position sensor 35, and the position or operation of the oil level of the hydraulic oil in the hydraulic oil storage tank 16 detected by the level sensor 36. Various data such as the amount (volume) of oil and the flow rate of hydraulic oil detected by the first and second flow rate sensors 37 and 38 are input.

Further, in the storage unit (memory) of the arithmetic unit 39, the specifications or specifications of the hydraulic cylinder 1 and the hydraulic oil supply / discharge mechanism 10, that is, the shapes of various components of the hydraulic cylinder 1 and the hydraulic oil supply / discharge mechanism 10 are stored in advance. , Dimensions, cross-sectional area, volume, etc. are stored. Specifically, for example, data of the following specifications or specifications of these components are stored (see FIG. 4).
-Inner diameter of cylinder 2 (outer diameter of piston 3): D
-Lowest and highest positions of the upper end surface of the piston 3: H ₁ , H ₂
-Thickness of piston 3 (dimensions in the vertical direction): h
-Outer diameter of piston rod 4: d
-Volume of the hydraulic oil accommodating portion of each component of the hydraulic oil supply / discharge mechanism 10: V ₃
・ Area of the cross section of the hydraulic oil storage tank 16

Further, when the hydraulic cylinder device S is operated in the storage unit (memory) of the arithmetic device 39 after the hydraulic cylinder device S is installed or after the hydraulic oil is completely drained by dismantling and repairing or the like. _{The amount V 0} (volume) of the hydraulic oil loaded (introduced) into the cylinder 1 or the hydraulic oil supply / discharge mechanism 10 is input (stored).

Hereinafter, a method for detecting a hydraulic oil leak in the hydraulic oil supply / discharge mechanism 10 by the hydraulic oil leak detecting means 34 will be described. In this case, the arithmetic unit 39 first uses the piston position sensor 35 at predetermined time intervals (for example, every 1 to 20 seconds) when the hydraulic cylinder 1 is in operation (including when the piston 3 is moving and stopped). The position H of the upper end surface of the piston 3, the lowest position H ₁ and the uppermost position H ₂ of the upper end surface of the piston 3, the thickness h of the piston 3, the inner diameter D of the cylinder 2 (outer diameter of the piston 3), and the piston rod. Based on the outer diameter d and the like of 4, the volume of the upper oil chamber 6 and the volume of the lower oil chamber 7 at that time are calculated. For example, when the piston 3 reciprocates between the upper and lower ends of the cylinder hollow, the volume V ₁ and the volume V ₂ of the lower oil chamber 7 of the upper oil chamber 6, respectively, Equations 1 and the following It can be calculated by 2.

Therefore, the total volume of the upper oil chamber 6 and the lower oil chamber 7 (V ₁ + V ₂ ) at this time, that is, the total amount of hydraulic oil in the upper oil chamber 6 and the lower oil chamber 7 (V ₁ + V ₂ ) is determined. It is expressed by the following formula 3.

As is clear from Equation 3, the total volume of the upper oil chamber 6 and the lower oil chamber 7, that is, the total amount of hydraulic oil contained in the upper oil chamber 6 and the lower oil chamber 7 when the hydraulic cylinder 1 is in operation ( The total volume) changes according to the position H of the upper end surface of the piston 3. Along with this, the amount (volume) of the hydraulic oil in the hydraulic oil storage tank 16 also changes. The volume of the hydraulic oil accommodating portion of the hydraulic oil supply / discharge mechanism 10, that is, the hydraulic oil accommodating amount is substantially constant.

For example, as shown in the graph G ₁ in FIG. 5 (a), the piston 3 starts to rise at time t _1, reaches the uppermost position in the time t _2, the begins to drop at time t _3, time and it reached the lowest position in the t _4. In this case, the volume of the volume and the lower oil chamber 7 of the upper oil chamber 6, respectively, changed as shown in the graph G ₂ and the graph G ₃ in FIG. 5 (b). _{The maximum volume C 2} of the lower oil chamber 7 _{is smaller than the maximum volume C 1} of the upper oil chamber 6 because the volume of the oil chamber is reduced by the piston rod 4. As a result, the total volume or working fluid capacity of the hydraulic cylinder 1 of the upper oil chamber 6 and a lower oil chamber 7 _(V 1 ₊ V _2), as shown in the graph G ₄ in FIG. 5 (c), the maximum value It varies in a concave between Q _1, the minimum value _{Q 2.} Along with this, the hydraulic oil storage capacity L of the hydraulic oil storage tank 16 changes convexly between the maximum value L ₁ and the minimum value L _{2 as shown by the graph G 5 in FIG. 5 (d).} Thus, linear functional relationship as shown in the graph G ₆ in FIG. 5 (e) between the hydraulic oil capacity of the hydraulic cylinder 1 and (V 1 _{+ V 2)} and the position H of the piston 3 is established, linear functional relationship as shown in the graph G ₇ in FIG. 5 (e) is established between the resulting position H of the hydraulic oil storage amount and the piston 3 of the hydraulic oil reservoir 16.

Further, the arithmetic unit 39 calculates the volume of the hydraulic oil accommodating portion of the hydraulic oil supply / discharge mechanism 10. Here, the hydraulic oil accommodating portion provides a space portion through which hydraulic oil flows or is filled with hydraulic oil in each component (excluding the hydraulic oil storage tank 16) of the hydraulic oil supply / discharge mechanism 10 when the hydraulic cylinder 1 is in operation. means. That is, the volume of the hydraulic oil accommodating portion corresponds to the amount (volume) of the hydraulic oil contained in each component of the hydraulic oil supply / discharge mechanism 10 when the hydraulic cylinder device S is in operation. That is, the arithmetic unit 39, during operation of the hydraulic cylinder device S, calculates the amount of hydraulic oil V ₃ to each component (excluding hydraulic oil reservoir 16) is accommodated in the hydraulic fluid supply and discharge mechanism 10. Note that storage amount V ₃ of the hydraulic fluid of the hydraulic fluid supply and discharge mechanism 10, unless there is a change in the specification to the components of the hydraulic fluid supply and discharge mechanism 10 is substantially constant.

Then, the arithmetic unit 39 determines the total volume (V ₁ + V ₂ ) of the upper oil chamber 6 and the lower oil chamber 7, that is, the hydraulic oil storage capacity (V ₁ + V ₂ ) of the upper oil chamber 6 and the lower oil chamber 7. , The volume of the hydraulic fluid storage part of the hydraulic fluid supply / discharge mechanism 10 (V ₃ ), that is, the hydraulic oil storage capacity of the hydraulic fluid supply / discharge mechanism 10 (V ₃ ), and the loading of hydraulic oil into the hydraulic cylinder device S V ₀ . Based on the following equation 4, the estimated hydraulic oil capacity Vs of the hydraulic fluid storage tank 16 is calculated by the following equation 4 assuming that the hydraulic fluid supply / discharge mechanism 10 has no hydraulic oil leakage.

After that, the arithmetic unit 39 calculates the hydraulic oil amount difference ΔV between the hydraulic oil content estimated value Vs (predicted value) and the hydraulic oil amount Vr (measured value) detected by the level sensor 36 according to the following equation 5. Calculate.

Then, if the hydraulic oil amount difference ΔV is equal to or higher than a predetermined threshold value (reference value) α (ΔV ≧ α), it is determined that the hydraulic oil leakage has occurred in the hydraulic oil supply / discharge mechanism 10. Further, in this case, the arithmetic unit 39 calculates the leakage amount or leakage speed of the hydraulic oil in the hydraulic fluid supply / discharge mechanism 10 based on the time-dependent change or integrated value of the hydraulic oil amount difference ΔV within a predetermined time.

Hereinafter, a method for detecting a hydraulic oil leak (a hydraulic oil leak inside a cylinder) between the upper oil chamber 6 and the lower oil chamber 7 via a gap between the cylinder 2 and the piston 3 by the hydraulic oil leak detecting means 34 will be described. explain. Even if such a leak of hydraulic oil inside the cylinder occurs, the total amount of hydraulic oil contained in the hydraulic cylinder device S does not change. Therefore, the method of detecting the leak of hydraulic oil in the hydraulic oil supply / discharge mechanism 10 is used. It is not possible to detect hydraulic oil leaks inside the cylinder.

First, when pressurized hydraulic oil is supplied to the upper oil chamber 6 and the piston 3 is moving downward, the gap between the cylinder 2 and the piston 3 from the upper oil chamber 6 to the lower oil chamber 7 is formed. A method for detecting hydraulic oil leakage through the piston will be described. In this case, the arithmetic unit 39 calculates the rate of change of the volume of the upper oil chamber 6 corresponding to the position of the piston 3 detected by the piston position sensor 35 with respect to time (hereinafter, referred to as “upper oil chamber volume change rate”). do.

Subsequently, the flow rate of the hydraulic oil flowing into the upper oil chamber 6 from the first oil passage 12 detected by the first flow sensor 37 and the volume change rate of the upper oil chamber, that is, the amount of the hydraulic oil in the upper oil chamber 6 ( The difference between the volume) and the rate of change over time (hereinafter referred to as the "upper oil chamber hydraulic oil flow rate difference") is calculated. Then, if the difference in the flow rate of the hydraulic oil in the upper oil chamber is equal to or greater than a preset threshold value (reference value), it is determined that the hydraulic oil has leaked from the upper oil chamber 6 to the lower oil chamber 7. Further, based on the integrated value of the flow rate difference of the hydraulic oil in the upper oil chamber from the uppermost position to the lowermost position of the piston 3, the upper oil chamber in one stroke in which the piston 3 descends from the uppermost position to the lowermost position. The amount of hydraulic oil leaking from 6 to the lower oil chamber 7 is calculated.

In this case, the flow rate of the hydraulic oil flowing out from the lower oil chamber 7 to the second oil passage 13 detected by the second flow sensor 38 and the time of the volume of the lower oil chamber 7 corresponding to the position of the piston 3. If the difference between the rate of change and the rate of change of the amount (volume) of hydraulic oil in the lower oil chamber 7 with respect to time is equal to or greater than a preset threshold value (reference value), the upper oil chamber 6 to the lower side It may be determined that the hydraulic oil has leaked to the oil chamber 7.

Next, when pressurized hydraulic oil is supplied to the lower oil chamber 7 and the piston 3 is moving upward, the cylinder 2 and the piston 3 from the lower oil chamber 7 to the upper oil chamber 6 A method for detecting hydraulic oil leakage through a gap will be described. In this case, the arithmetic unit 39 first refers to the rate of change of the volume of the lower oil chamber 7 corresponding to the position of the piston 3 detected by the piston position sensor 35 with respect to time (hereinafter, referred to as “lower oil chamber volume change rate”. ) Is calculated.

Subsequently, the flow rate of the hydraulic oil flowing into the lower oil chamber 7 from the second oil passage 13 detected by the second flow sensor 38 and the volume change rate of the lower oil chamber, that is, the hydraulic oil in the lower oil chamber 7. The difference between the amount (volume) of the oil and the rate of change with time (hereinafter referred to as "lower oil chamber hydraulic oil flow rate difference") is calculated. Then, if the difference in the flow rate of the hydraulic oil in the lower oil chamber is equal to or greater than a preset threshold value (reference value), it is determined that the hydraulic oil has leaked from the lower oil chamber 7 to the upper oil chamber 6. Further, the lower side in one stroke in which the piston 3 rises from the lowest position to the uppermost position based on the integrated value of the flow rate difference of the lower oil chamber hydraulic oil until the piston 3 rises from the lowest position to the uppermost position. The amount of hydraulic oil leaking from the oil chamber 7 to the upper oil chamber 6 is calculated.

In this case, the flow rate of the hydraulic oil flowing out from the upper oil chamber 6 to the first oil passage 12 detected by the first flow sensor 37 and the change in the volume of the upper oil chamber 6 corresponding to the position of the piston 3 with respect to time. If the difference between the rate, that is, the rate of change of the amount (volume) of hydraulic oil in the upper oil chamber 6 with respect to time is equal to or more than a preset threshold value (reference value), the lower oil chamber 7 to the upper oil chamber 6 It may be determined that the hydraulic oil has leaked to.

As described above, according to the hydraulic cylinder device S or the hydraulic liquid leakage detection method according to the embodiment of the present invention, the hydraulic oil supply / discharge mechanism of the hydraulic cylinder device S is used when the hydraulic cylinder 1 or piston 3 is moving or stopped. The occurrence of hydraulic fluid leakage in No. 10 can be detected quickly and early. Further, a hydraulic oil leak (a hydraulic oil leak inside the cylinder) between the upper oil chamber 6 and the lower oil chamber 7 when the piston 3 is moved through the gap between the cylinder 2 and the piston 3 can be quickly and quickly caused. Can be detected.

S Hydraulic cylinder device, P1 A port, P2 B port, P3 P port, P4 T port, 1 hydraulic cylinder, 2 cylinder, 3 piston, 4 piston rod, 5 load, 6 upper oil chamber, 7 lower oil chamber, 10 Hydraulic oil supply / discharge mechanism, 11 direction switching valve, 12 1st oil passage, 13 2nd oil passage, 14 3rd oil passage, 15 4th oil passage, 16 hydraulic oil storage tank, 17 oil filter, 18 electric motor, 19 hydraulic pump , 20 1st bypass oil passage, 21 relief valve, 25 1st piston operated check valve, 26 1st check valve with flow control valve, 26a flow control valve, 26b check valve, 27 2nd pilot operated check valve Stop valve, 28 Flow control valve with 2nd check valve, 28a Flow control valve, 28b Check valve, 30 1st on-off valve, 31 2nd on-off valve, 32 2nd bypass oil passage, 33 3rd on-off valve, 34 Hydraulic oil leak detection means, 35 piston position detection sensor, 36 level sensor, 37 first flow sensor, 38 second flow sensor, 39 arithmetic unit, 40 cylindrical member, 41 upper end plate, 42 lower end plate, 43 upper end In-plate oil passage, 43a horizontal hole, 43b vertical hole, 45 hole, 46 1st piston packing, 47 1st annular groove, 48 2nd piston packing, 49 2nd annular groove, 51 support member, 52 piston rod insertion hole, 53 1st rod packing, 54 2nd rod packing, 60 vertical hydraulic oil passage, 61 horizontal hydraulic oil passage, 62 1st check valve, 63 valve seat, 64 valve body, 65 coil spring, 66 2nd check valve, 67 Valve seat, 68 valve body, 69 coil spring, 71 rod-shaped member.

Claims (5)

The cylinder, the piston that is fitted into the hollow portion of the cylinder and reciprocates in the direction in which the central axis of the cylinder extends, and the piston that is coupled to the lower end of the piston and passes through the hole in the lower end wall of the cylinder to the outside of the cylinder from the hollow portion. A hydraulic cylinder having an extending piston rod, an upper liquid chamber formed of the hollow portion above the piston, and a lower liquid chamber formed of the hollow portion below the piston.
The hydraulic fluid storage tank, the hydraulic fluid passage arranged between the hydraulic fluid storage tank and the hydraulic cylinder, and the hydraulic fluid in the hydraulic fluid storage tank via the hydraulic fluid passage provided in the hydraulic fluid passageway. A hydraulic fluid supply / discharger having a pump for supplying the hydraulic fluid to the hydraulic cylinder and a direction switching valve provided in the hydraulic fluid passage on the hydraulic cylinder side of the pump to switch the supply / discharge path of the hydraulic fluid in the hydraulic fluid passage. Mechanism and
A hydraulic cylinder device including a hydraulic fluid leak detecting means for detecting a hydraulic fluid leak in the hydraulic fluid supply / discharge mechanism.
The working fluid leak detecting means is
A piston position detector that detects the position of the piston in the cylinder in the extending direction of the cylinder center axis, and a piston position detector.
A hydraulic fluid amount detector that detects the hydraulic fluid volume in the hydraulic fluid storage tank, and
The volume of the upper liquid chamber and the lower liquid chamber corresponding to the position of the piston detected by the piston position detector, the volume of the hydraulic fluid accommodating portion of the hydraulic fluid supply / drainage mechanism, and the hydraulic cylinder device. A hydraulic fluid amount estimator that calculates an estimated value of the hydraulic fluid in the hydraulic fluid storage tank based on the amount of the hydraulic fluid loaded in the
If the difference between the working fluid amount estimated value calculated by the working fluid amount estimator and the working fluid amount detected by the working fluid amount detector is equal to or more than a preset threshold value, the working fluid supply / discharge is performed. A hydraulic cylinder device comprising a hydraulic fluid leak determining device for determining that a hydraulic fluid leak has occurred in the mechanism. The working fluid amount estimator is
The volume of the upper liquid chamber and the lower liquid chamber corresponding to the position of the piston detected by the piston position detector, the volume of the hydraulic fluid accommodating portion of the hydraulic fluid passage, and the hydraulic fluid accommodating portion of the pump. The estimated value of the hydraulic fluid in the hydraulic fluid storage tank is calculated based on the volume of the hydraulic fluid, the volume of the hydraulic fluid accommodating portion of the direction switching valve, and the volume of the hydraulic fluid loaded in the hydraulic cylinder device. The hydraulic cylinder device according to claim 1, wherein the hydraulic cylinder device is characterized. The hydraulic fluid amount detector is characterized in that it detects the hydraulic fluid amount in the hydraulic fluid storage tank based on the liquid level of the hydraulic fluid in the hydraulic fluid storage tank and the area of the cross section of the hydraulic fluid storage tank. , The hydraulic cylinder device according to claim 1 or 2. The cylinder, the piston that is fitted into the hollow portion of the cylinder and reciprocates in the direction in which the central axis of the cylinder extends, and the piston that is coupled to the lower end of the piston and passes through the hole in the lower end wall of the cylinder to the outside of the cylinder from the hollow portion. A hydraulic cylinder having an extending piston rod, an upper liquid chamber formed of the hollow portion above the piston, and a lower liquid chamber formed of the hollow portion below the piston.
The hydraulic fluid storage tank, the hydraulic fluid passage arranged between the hydraulic fluid storage tank and the hydraulic cylinder, and the hydraulic fluid in the hydraulic fluid storage tank via the hydraulic fluid passage provided in the hydraulic fluid passageway. A hydraulic fluid supply / discharger having a pump for supplying the hydraulic fluid to the hydraulic cylinder and a direction switching valve provided in the hydraulic fluid passage on the hydraulic cylinder side of the pump to switch the supply / discharge path of the hydraulic fluid in the hydraulic fluid passage. A method for detecting a hydraulic leak in a hydraulic cylinder device equipped with a mechanism.
The position in the cylinder in the extending direction of the cylinder central axis of the piston is detected, and the position is detected.
Detecting the amount of hydraulic fluid in the hydraulic fluid storage tank,
The volumes of the upper liquid chamber and the lower liquid chamber corresponding to the position of the piston, the volume of the hydraulic fluid accommodating portion of the hydraulic fluid supply / discharge mechanism, and the amount of the hydraulic fluid loaded in the hydraulic cylinder device. Based on, the estimated value of the amount of hydraulic fluid in the hydraulic fluid storage tank is calculated.
If the difference between the calculated hydraulic fluid amount estimated value and the detected hydraulic fluid amount is equal to or greater than a preset threshold value, it is determined that the hydraulic fluid has leaked to the hydraulic fluid supply / discharge mechanism. A method for detecting a hydraulic leak in a pressure cylinder device. The liquid according to claim 4 , wherein the amount of the hydraulic liquid in the hydraulic liquid storage tank is detected based on the liquid level of the hydraulic liquid in the hydraulic liquid storage tank and the area of the cross section of the hydraulic liquid storage tank. A method for detecting hydraulic fluid leakage in a pressure cylinder device.

Images