Actuator operation inspection system

Abstract

The present invention comprises: a pump for transferring a fluid at a predetermined hydraulic pressure; an actuator having a piston moved by means of the hydraulic pressure of the transferred fluid; a recovery tank for storing the fluid discharged from the actuator by means of the movement of the piston; a recovery pressure sensor, which is a switch turned on or off by means of the recovery pressure of the fluid discharged from the actuator; and a control unit for inspecting a moving state of the piston of the actuator on the basis of the operation of the recovery pressure sensor.

Description

Actuator operation inspection system

[0001] The present invention relates to a system for inspecting the operating status of an actuator, and more particularly, to a system for inspecting whether a hydraulically operated actuator has operated accurately according to control.

[0002] To operate a hydraulic actuator, for example to open / close, a hydraulic pump must be used to compress fluid and transmit hydraulic pressure to the actuator.

[0003] In order to control the actuator to open / close by controlling the hydraulic pressure, at least one hydraulic control valve (mainly a solenoid valve) is mounted on the actuator, and the hydraulic control valve is controlled to supply fluid to any position of the actuator.

[0004] When the open-side hydraulic control valve is opened to open the actuator, compressed hydraulic pressure is transferred to the actuator, causing the actuator to operate open. This process generates pressure between the hydraulic control valve and the actuator. Measuring this pressure can determine whether the actuator is open. Typically, a pressure sensor (pressure switch) is installed downstream of the hydraulic control valve to detect the pressure between the hydraulic control valve and the actuator.

[0005] Conventional methods for detecting the operating status of an actuator by detecting the pressure between the hydraulic control valve and the actuator can detect a failure of the hydraulic control valve because the pressure is not generated when the hydraulic control valve malfunctions and causes a hydraulic leak. However, even when the actuator is not moving due to problems such as sticking or valve overload, pressure is still generated, making it impossible to detect a failure of the actuator. In other words, it is impossible to detect a case where the hydraulic control valve is normal but the actuator is malfunctioning.

[0006] In addition, the method of detecting the operating status of the actuator by detecting the pressure between the hydraulic control valve and the actuator requires a lot of time to check the pressure sensor because the movement of the actuator can be detected only when the sensitivity of the pressure sensor is appropriately adjusted according to the distance between the hydraulic control valve and the actuator.

[0007] Meanwhile, for typical actuators operating at 100 to 150 bar, pressure sensors measuring hydraulic pressure require high pressure and a wide measurement range. This necessitates expensive pressure sensors. Furthermore, because pressure sensors are used in a high pressure range, their durability is compromised.

[0008] Due to these problems, conventionally, additional sensors such as position sensors and limit switches are installed in actuators, but this has the disadvantage of requiring additional sensor installation.

[0009] Meanwhile, reference can be made to a prior art (publication patent 10-2009-0070165) that discloses a structure installed in the return line of a hydraulic cylinder to check for leakage of operating oil.

[0010] According to the above-mentioned prior art, a detection means capable of detecting leakage of operating fluid is placed on the return line side of the safety valve of the cylinder on the mast of the forklift, and by checking the detected leaked operating fluid, normal operation of the safety valve is ensured.

[0011] However, these conventional technologies only suggest methods such as adding hydraulic pressure by determining the degree of leakage from the cylinder, and do not suggest a configuration for checking the operating status of the cylinder or safety valve.

[0012] The present invention seeks to provide a system and method capable of accurately detecting the operating state of an actuator.

[0013] The actuator operation inspection system according to the present invention for achieving the above-described task provides the following solutions.

[0014] 1. A hydraulic control valve for remotely controlling the opening / closing of a hydraulically operated actuator and valve, and a heterogeneous pressure sensor (Pressure Switch) installed in a line supplying fluid to the actuator and a line recovering the fluid to a recovery tank (HPU) are used to detect the opening / closing of the actuator.

[0015] 2. A pressure sensor (Pressure Switch) is installed at the C contact (switching contact) at the front end of the hydraulic control valve for controlling the open / close of the actuator and for signal detection, and a pressure sensor is also installed at the B contact (Normal Close) at the rear end of the hydraulic control valve.

[0016] 3. The actuator is configured such that a flow path is formed on both sides through which fluid is introduced or withdrawn, the shaft moves between the flow paths, and the fluid is withdrawn from the flow path opposite to the flow path through which the fluid is introduced.

[0017] 4. The shaft moving between the actuator's euros is configured to rotate the gear to open / close the valve.

[0018] 5. The detection range of the pressure sensor at the B contact (normally closed) at the rear end of the hydraulic control valve can be 10 bar or more.

[0019] 6. When the pressure sensor (B contact) of the line recovered upon opening of the actuator detects a pressure exceeding a preset value, the signal line is disconnected, and when the pressure below the preset value is detected as the actuator reaches the final position, the disconnected signal line is connected to recognize that the actuator has completed opening.

[0020] 7. When a pressure sensor (B contact) of a line recovered at the time of closing detects a pressure exceeding a preset value, the signal line is disconnected, and when the final position is reached and the pressure is detected to be less than the preset value, the disconnected signal line is connected to recognize the operation of the actuator as a final close.

[0021] The actuator operation inspection system according to the present invention can be configured as follows.

[0022] An actuator operation inspection system may include a pump that transfers fluid at a predetermined hydraulic pressure; an actuator that moves a piston by the hydraulic pressure of the transferred fluid; a recovery tank that stores fluid discharged from the actuator by the movement of the piston; a recovery pressure sensor that is a switch that is turned on or off by the recovery pressure of the fluid discharged from the actuator; and a control unit that inspects the movement state of the piston of the actuator based on the operation of the recovery pressure sensor.

[0023] Here, the actuator may be configured such that the piston can move to a first side or a second side, which are opposite to each other, and when the fluid is transferred to the first side, the piston moves to the second side so that the fluid is discharged from the second side, and when the fluid is transferred to the second side, the piston moves to the first side so that the fluid is discharged from the first side. In addition, the actuator operation inspection system may further include an operating pressure sensor that is switched by the operating pressure of the fluid transferred to the first side of the actuator. In addition, the control unit may inspect the operating state of the actuator based on the switching of the operating pressure sensor when the fluid is transferred to the first side of the actuator to move the piston to the second side, and may inspect the operating state of the actuator based on the operation of the recovery pressure sensor when the fluid is transferred to the second side of the actuator to move the piston to the first side.

[0024] Meanwhile, the actuator may be configured such that the piston can move to a first side or a second side in opposite directions, and when the fluid is transferred to the first side, the piston moves to the second side so that the fluid is discharged from the second side, and when the fluid is transferred to the second side, the piston moves to the first side so that the fluid is discharged from the first side. In addition, the actuator operation inspection system may further include an operating pressure sensor that is switched by the operating pressure of the fluid transferred to the first side of the actuator and the recovery pressure of the fluid transferred from the first side, and the operating pressure sensor may be a C-contact switching type sensor that couples a common contact to a first contact point or a second contact point by the operating pressure or the recovery pressure, and further, the recovery pressure sensor may be a switching type sensor that turns on or off two contact points by the recovery pressure. In addition, the actuator operation inspection system may include a detection circuit configured by connecting the operating pressure sensor and the recovery pressure sensor in series in a manner of connecting a common contact of the operating pressure sensor and one contact of the recovery pressure sensor. In addition, the control unit may inspect the operating state of the actuator based on whether another contact of the recovery pressure sensor is connected to one of the first contact and the second contact of the operating pressure sensor.

[0025] Additionally, the recovery tank may further include a check valve to prevent the fluid within the recovery tank from flowing back toward a switching valve configured to change the path of the fluid to control the operation of the actuator. Furthermore, the recovery pressure sensor may be positioned between the recovery side of the switching valve and the check valve.

[0026] According to the present invention including the configuration described above, the open / close operation status of the actuator can be accurately detected even without additionally installing a sensor such as a position measuring device or a limit switch to the actuator.

[0027] Additionally, since the pressure of the fluid recovered from the actuator is relatively low, typically in the range of 10 to 30 bar, a pressure sensor with a narrow allowable pressure range can be used, allowing for the use of a low-cost sensor, and since the pressure sensor is operated at a low pressure, durability is improved.

[0028] Figure 1 is a schematic diagram of an actuator operation inspection system according to the present invention.

[0029] Figure 2 illustrates a more practical implementation example of an actuator operation inspection system according to the present invention.

[0030] FIG. 3 is a drawing explaining the operation of an actuator operation inspection structure according to the prior art and an actuator operation inspection system according to the present invention.

[0031] In order to operate an actuator, it is necessary to consider not only the fluid that flows in the operating direction to supply hydraulic pressure to operate the actuator, but also the fluid that is already present inside the actuator and is discharged and recovered as the actuator operates.

[0032] The recovered fluid is returned to the tank (or HPU; Hydraulic Power Unit), compressed again by the hydraulic pump, and recirculated.

[0033] This recovered fluid can only be discharged and recovered when the actuator is operating normally. If the actuator is not moving, hydraulic pressure may be generated in the direction of operation, but no fluid movement occurs. Meanwhile, the fluid recovered from the actuator has the characteristic of maintaining a constant pressure regardless of the distance between the hydraulic control valve and the actuator.

[0034] Therefore, the operating status of the actuator can be determined by detecting the pressure of the recovered fluid, and this principle is the basic element of the present invention.

[0035] Figure 1 is a schematic diagram of an actuator operation inspection system according to the present invention. Referring to the drawing, the actuator operation inspection system according to the present invention may include a pump (130), an actuator (100), a recovery tank (140), a recovery pressure sensor (145), and a control unit (150).

[0036] The pump (130) is configured to pressurize and transfer a fluid (or operating oil) that forms hydraulic pressure for operating the actuator (100) at a predetermined pressure.

[0037] The actuator (100) is configured to receive a fluid that is pressurized and transported by a pump (130), and to move a piston contained therein by the hydraulic pressure of the supplied fluid, thereby operating a driving mechanism connected to the piston. Here, the piston is an example of a structure that can be moved by hydraulic pressure within the actuator, and may be a vane or a screw, and is used as a term encompassing any structure that can be moved in any direction by hydraulic pressure.

[0038] The actuator (100) may have at least two fluid inlets and outlets (a, b), and at least one inlet and outlet may be configured to move the piston to the first side by the inflowing fluid, and at least one opposite inlet and outlet may be configured to move the piston to the second side by the inflowing fluid.

[0039] Meanwhile, when fluid flows in through one of the inlets and outlets and the piston moves toward the first side, the fluid built into the second side of the piston can be discharged through the opposite inlet and outlet. The discharged fluid is transferred to the recovery tank (140).

[0040] The recovery tank (140) recovers and stores the fluid discharged from the actuator (100). The stored fluid can be recirculated by the pump (130).

[0041] The recovery pressure sensor (145) may be configured to turn the circuit on or off by the hydraulic pressure (i.e., recovery pressure) of the fluid discharged from the actuator (100), and may be a switch that turns at least two contacts on or off. The recovery pressure sensor (145) may be an A-contact type switch, or may be a B-contact type switch.

[0042] The recovery pressure sensor (145) may be positioned at any location between the actuator (100) and the recovery tank (140), preferably between the recovery side of the switching valve controlling the operation of the actuator (100) and the recovery tank (see FIG. 2). More preferably, the recovery pressure sensor (145) may be positioned between the switching valve (120) and the check valve (146) (see FIG. 3 (c), (d)).

[0043] The control unit (150) controls the operation of the pump (130) and controls the supply of pressurized fluid by the pump (130) to the actuator (100). For the purpose of controlling the supply of pressurized fluid, one or more valves may be added to the system (e.g., a switching valve).

[0044] Meanwhile, the control unit (150) can operate the recovery pressure sensor (145) and check the operating status of the actuator (100) based on the switching operation of the recovery pressure sensor (145).

[0045] The control unit (150) can stop the fluid supply to the actuator (100) or output various types of alarms indicating a failure of the actuator (100) based on the operating status of the actuator (100).

[0046] For example, if the control unit detects that the recovery pressure sensor (145) is turned on or off by the recovery pressure, it may determine that the fluid has been normally supplied to one side of the actuator and that the fluid is being normally discharged from the other side of the actuator as a result.

[0047] A more practical implementation example of the actuator operation inspection system according to the present invention having the above-described configuration is described with reference to Fig. 2. Fig. 2 additionally illustrates and describes a switching valve (120) in the system illustrated in Fig. 1.

[0048] The switching valve (120) has, on one side, a connection portion (P) that can receive pressurized fluid from the pump (130) and a connection portion (T) that can discharge fluid recovered from the actuator to a recovery tank (140). In addition, the switching valve (120) has, on the other side, a connection portion (A) that can supply fluid to one side (a) of the actuator or recover the discharged fluid, and a connection portion (B) that can supply fluid to the other side (b) of the actuator or recover the discharged fluid.

[0049] Inside the switching valve (120), a line switching mechanism (124) can be arranged that is driven according to the control of the control unit (150) and can selectively operate in a 'parallel mode' in which the connection part (P) is connected to the connection part (A) and the connection part (T) is connected to the connection part (B), and in a 'cross mode' in which the connection part (P) is connected to the connection part (B) and the connection part (T) is connected to the connection part (A) (see FIG. 3).

[0050] In this structure, the control unit (150) can control the operation of the switching valve (120) to couple the pressurized fluid from the pump (130) to the connection portion (a) or connection portion (b) of the actuator, thereby controlling the operation of the actuator (100).

[0051] Meanwhile, as the actuator (100) operates, that is, as the piston inside the actuator moves, the fluid pushed out by the piston can be discharged from the connection part (b) or the connection part (a) and transferred to the recovery tank (140) through the switching valve (120).

[0052] At this time, a recovery pressure sensor (145) can be placed in the line between the switching valve (120) and the recovery tank (140), and the recovery pressure sensor (145) is operated by the pressure of the fluid pushed out by the piston (i.e., the recovery pressure).

[0053] The control unit (150) can determine whether the piston of the actuator (100) is moving normally and / or has moved completely based on the operating status of the recovery pressure sensor (145).

[0054] FIG. 3 is a drawing for explaining the operation of an actuator operation inspection system according to the present invention. Through the drawing, the operation of the actuator operation inspection system according to the present invention is explained together with the operation of a switching valve (120) for operating an actuator (100). In addition, for reference, the actuator operation inspection structure in the existing technology is explained together with the operation of the switching valve (120).

[0055] Figures 3 (a) and (b) show the actuator operation inspection structure in the existing technology. Figure 3 (a) is defined as an "open" state of the actuator (100) in which the line switching mechanism (124) is moved to one side to connect the pump-side connection (P) to the connection (B), thereby allowing the hydraulic pressure of the fluid to act on the connection (b) of the actuator through the connection (B). At this time, the fluid discharged from the connection (a) of the actuator can be recovered to the tank (140) through the tank-side connection (T) through the connection (A).

[0056] Meanwhile, in the existing technology, in order to inspect the operating status of the actuator (100), operating pressure sensors (121, 122) are installed between the line switching mechanism (124) and the connection part (A) and between the line switching mechanism (124) and the connection part (B), respectively. Since these installation locations are locations where the hydraulic pressure for operating the actuator (100) is directly applied, the operating pressure sensors (121, 122) must have a high-pressure operating range.

[0057] The operating pressure sensor (121, 122) in the existing technology may be a switch that operates to turn contacts on or off by operating pressure. This operating pressure sensor (121, 122) may be an A-contact type switch or a B-contact type switch.

[0058] In an operating state such as (a) of Fig. 3, the operating pressure sensor (122) on the B side may be exposed to a high pressure of 120 bar. At this time, the circuit may be turned on as 120 bar is applied to the operating pressure sensor (122) on the B side within the switching valve, and when the on state of the operating pressure sensor (122) is detected, it may be determined that the actuator (100) has been operated in an open state. However, as mentioned above, operating pressure may be generated even in a situation where the actuator (100) is stuck or a specific valve related to the actuator is overloaded, and therefore, the detection circuit still cannot detect situations such as the actuator being stuck or the specific valve related to the actuator being overloaded.

[0059] The right side of (a) of Fig. 3 schematically shows the configuration of a detection circuit including operating pressure sensors (121, 122). It shows that the operating pressure sensor (122) on the B side within the switching valve was operated by the pressure of the fluid (e.g., switched on) (red mark). On the other hand, the operating pressure sensor (121) on the A side within the switching valve did not operate (e.g., switched off) (black mark) because the hydraulic pressure of the recovered fluid was applied. This is because the operating pressure sensors (121, 122) on the A side and the B side are sensors configured to operate at a high pressure in the range of 120 bar, and therefore will not operate by the recovery pressure formed in the range of 10 bar.

[0060] Thus, the system will determine that the actuator (100) is operating in an open state simply by detecting that the operating pressure sensor (122) on the B side is turned on.

[0061] Meanwhile, (b) of Fig. 3 shows a state in which the line switching mechanism (124) has moved to the other side, the pump-side connection part (P) is connected to the connection part (A), and the pump-side connection part (T) is connected to the connection part (B). In this state, the hydraulic pressure of the pump (130) acts on the connection part (a) of the actuator, and the fluid discharged from the connection part (b) of the actuator can be recovered to the recovery tank (140) through the connection part (B). This state is defined as the “closed” state of the actuator (100).

[0062] At this time, high pressure (i.e., operating pressure) for operating the actuator (100) is applied to the operating pressure sensor (121) on the A side of the switching valve. Meanwhile, low pressure (i.e., recovery pressure) due to the fluid recovered from the actuator (100) is applied to the operating pressure sensor (122) on the B side.

[0063] In the detection circuit illustrated in the right part of (b) of Fig. 3, the operating pressure sensor (121) on the A side within the switching valve shows that the sensor has been operated (on state) due to the high pressure from the pump (130). Conversely, the operating pressure sensor (122) on the B side is not operated (off state) because the hydraulic pressure of the recovered fluid is applied.

[0064] According to this detection circuit, if it detects that the operating pressure sensor (121) on the A side inside the switching valve is in the on state, it is determined that the actuator has been operated in the closed state. However, as mentioned above, even in a situation where the actuator (100) is stuck or the valve is overloaded (because the operating pressure can still be applied to the operating pressure sensor (121) on the A side), the operating pressure sensor (121) on the A side can be switched to the on state, and therefore, the above-mentioned problematic situations still cannot be detected by this detection circuit.

[0065] Meanwhile, the operation and detection circuit configuration of the actuator operation inspection system according to the present invention is as follows.

[0066] As shown in (c) and (d) of FIG. 3, the actuator operation inspection system according to the present invention places an operating pressure sensor (126) that operates by high and low pressure only in one line where high pressure (i.e., operating pressure) for operating the actuator (100) is applied, and a recovery pressure sensor (145) that operates by low pressure (i.e., recovery pressure) lower than the operating pressure is placed in the line through which the recovered fluid flows.

[0067] Here, the operating pressure sensor (126) may be a C-contact switch type sensor that connects the common contact to the first contact or the second contact. This operating pressure sensor (126) may be operated to switch to the first contact when high pressure (e.g., operating pressure) is applied, and to switch to the second contact when low pressure (e.g., recovery pressure) is applied.

[0068] Meanwhile, a check valve (146) may be placed between the switching valve (120) and the recovery tank to prevent the fluid in the recovery tank from flowing back toward the switching valve.

[0069] In addition, the recovery pressure sensor (145) in the present invention is preferably placed between the switching valve (120) and the check valve (146), because the recovery pressure can be formed at this location and the recovery pressure can be measured well.

[0070] Meanwhile, the actuator operation inspection system according to the present invention implements a detection circuit by connecting an operation pressure sensor (126) and a recovery pressure sensor (145) in series (see drawing).

[0071] (c) of Fig. 3 is an “open” state of the actuator (100) in which the hydraulic pressure of the fluid is adjusted to act on the connection (b) of the actuator through the connection (B) by moving the line switching mechanism (124) of the switching valve to one side and connecting the pump-side connection (P) to the connection (B). At this time, the fluid discharged from the connection (a) of the actuator can be recovered to the tank (140) through the tank-side connection (T) through the connection (A).

[0072] In this state, high pressure for operating the actuator (100) is applied to the operating pressure sensor (126) on the B side. Meanwhile, at this time, the pressure of the recovered fluid is also applied to the recovery pressure sensor (145). If the actuator (100) has been operated normally by the fluid flowing into the connection portion (b), the recovery pressure by the fluid discharged from the connection portion (a) of the actuator will be applied to the recovery pressure sensor (145). Therefore, the control unit of the system can determine in which direction the actuator (100) has been operated and whether it has been operated normally based on the operating states of the operating pressure sensor (126) and the recovery pressure sensor (145).

[0073] On the right side of Fig. 3 (c), the configuration of a detection circuit including an operating pressure sensor (126) and a recovery pressure sensor (145) of an actuator operation inspection system according to the present invention is shown. It differs from the detection circuit of existing technologies in that the operating pressure sensor (126) and the recovery pressure sensor (145) are connected in series.

[0074] In the above detection circuit, the operating pressure sensor (126) is operated by the operating pressure of the fluid and the contact is switched (switched to the B side), and the recovery pressure sensor (145) is also operated by the recovery pressure of the recovered fluid (on state). When the control unit (150) detects that the operating pressure sensor (126) is switched to the B side and the recovery pressure sensor (145) is turned on, it can determine that the actuator (100) is operating normally and has been switched to the open state.

[0075] Meanwhile, (d) of FIG. 3 shows a “closed” state of the actuator (100) in which the line switching mechanism (124) of the switching valve (120) is moved to the other side, so that the pump-side connection part (P) is connected to the connection part (A) and the pump-side connection part (T) is connected to the connection part (B). In this state, the hydraulic pressure of the pump (130) acts on the connection part (a) of the actuator, and the fluid discharged from the connection part (b) of the actuator can be recovered to the recovery tank (140) via the recovery pressure sensor (145) through the connection part (B).

[0076] At this time, the recovery pressure of the fluid recovered from the actuator (100) is applied to the operating pressure sensor (126), so that the contact can be switched (switched to the A side), and the recovery pressure is also applied to the recovery pressure sensor (145), so that it is switched on. Then, when the control unit (150) detects that the operating pressure sensor (126) is switched to the A side and the recovery pressure sensor (145) is turned on, it can determine that the actuator (100) is operating normally and has been switched to the closed state.

Claims

1. A pump that transports fluid at a given hydraulic pressure; An actuator in which a piston moves by the hydraulic pressure of the fluid being transported; A recovery tank that stores fluid discharged from the actuator by movement of the piston; A recovery pressure sensor which is a switch that is turned on or off by the recovery pressure of the fluid discharged from the actuator; and An actuator operation inspection system, comprising a control unit that inspects the movement state of the piston of the actuator based on the operation of the recovery pressure sensor.

2. In paragraph 1, The actuator is configured such that the piston can move to a first side or a second side in opposite directions, and when the fluid is transferred to the first side, the piston moves to the second side so that the fluid is discharged from the second side, and when the fluid is transferred to the second side, the piston moves to the first side so that the fluid is discharged from the first side. The above actuator operation inspection system further includes an operating pressure sensor that is switched by the operating pressure of the fluid transferred to the first side of the actuator, The above control unit, When the fluid is transferred to the first side of the actuator to move the piston to the second side, the operating status of the actuator is inspected based on the switching of the operating pressure sensor, and An actuator operation inspection system characterized in that the operating status of the actuator is inspected based on the operation of the recovery pressure sensor when the fluid is transferred to the second side of the actuator to move the piston to the first side.

3. In paragraph 1, The actuator is configured such that the piston can move to a first side or a second side in opposite directions, and when the fluid is transferred to the first side, the piston moves to the second side so that the fluid is discharged from the second side, and when the fluid is transferred to the second side, the piston moves to the first side so that the fluid is discharged from the first side. The actuator operation inspection system further includes an operating pressure sensor that is switched by the operating pressure of the fluid transferred to the first side of the actuator and the recovery pressure of the fluid transferred from the first side, - the operating pressure sensor is a C-contact switching type sensor that couples a common contact to a first contact point or a second contact point by the operating pressure or the recovery pressure, and further, the recovery pressure sensor is a switching type sensor that turns on or off two contact points by the recovery pressure. In addition, the actuator operation inspection system includes a detection circuit configured by connecting the operating pressure sensor and the recovery pressure sensor in series in a manner of connecting a common contact of the operating pressure sensor and one contact of the recovery pressure sensor, An actuator operation inspection system, characterized in that the control unit inspects the operating status of the actuator based on whether another contact of the recovery pressure sensor is connected to either the first contact or the second contact of the operating pressure sensor.

4. In paragraph 1, The above recovery tank further includes a check valve for preventing the fluid in the recovery tank from flowing back toward a switching valve configured to switch the path of the fluid to control the operation of the actuator. An actuator operation inspection system, characterized in that the above recovery pressure sensor is arranged between the recovery side of the switching valve and the check valve.

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